Evolution of dispersal and the analysis of a resource flourished population model with harvesting

This study explores a spatially distributed harvesting model that signifies the outcome of the competition of two species in a heterogeneous environment. The model is controlled by reaction-diffusion equations with resource-based diffusion strategies. Two different situations are maintained by the harvesting effects: when the harvesting rates are independent in space and do not exceed the intrinsic growth rate; and when they are proportional to the time-independent intrinsic growth rate. In particular, the competition between both species differs only by their corresponding migration strategy and harvesting intensity. We have computed the main results for the global existence of solutions that represent either coexistence or competitive exclusion of two competing species depending on the harvesting levels and different imposed diffusion strategies. We also established some estimates on harvesting efforts for which coexistence is apparent. Also, some numerical results are exhibited in one and two spatial dimensions, which shed some light on the ecological implementation of the model.

using polymer harvesting and expired COVID-19 disinfectant for pretreatment

This study evaluates the repurposing of expired isopropanol (IPA) COVID-19 disinfectant (64% w/w) to pretreat algal biomass for enhancing methane (CH4) yield. The impact of harvesting methods (centrifugation and polymer flocculation) and microwave pretreatment on CH4 production from Scenedesmus sp. microalgal biomass were also investigated. Results show minimal impact of harvesting methods on the CH4 yield, with wet centrifuged and polymer-harvested biomass exhibiting comparable and low CH4 production at 66 and 74 L/kgvolatile solid, respectively. However, microalgae drying significantly increased CH4 yield compared to wet biomass, attributed to cell shrinkage and enhanced digestibility. Consequently, microwave and IPA pretreatment significantly enhanced CH4 production when applied to dried microalgae, yielding a 135% and 212% increase, respectively, compared to non-pretreated wet biomass. These findings underscore the advantage of using dried Scenedesmus sp. over wet biomass and highlight the synergistic effect of combining oven drying with IPA treatment to boost CH4 production whilst reducing COVID-19 waste.

Muscle Morphology Does Not Solely Determine Knee Flexion Weakness After Anterior Cruciate Ligament Reconstruction with a Semitendinosus Tendon Graft: A Combined Experimental and Computational Modeling Study

The distal semitendinosus tendon is commonly harvested for anterior cruciate ligament reconstruction, inducing substantial morbidity at the knee. The aim of this study was to probe how morphological changes of the semitendinosus muscle after harvest of its distal tendon for anterior cruciate ligament reconstruction affects knee flexion strength and whether the knee flexor synergists can compensate for the knee flexion weakness. Ten participants 8-18 months after anterior cruciate ligament reconstruction with an ipsilateral distal semitendinosus tendon autograft performed isometric knee flexion strength testing (15°, 45°, 60°, and 90°; 0° = knee extension) positioned prone on an isokinetic dynamometer. Morphological parameters extracted from magnetic resonance images were used to inform a musculoskeletal model. Knee flexion moments estimated by the model were then compared with those measured experimentally at each knee angle position. A statistically significant between-leg difference in experimentally-measured maximal isometric strength was found at 60° and 90°, but not 15° or 45°, of knee flexion. The musculoskeletal model matched the between-leg differences observed in experimental knee flexion moments at 15° and 45° but did not well estimate between-leg differences with a more flexed knee, particularly at 90°. Further, the knee flexor synergists could not physiologically compensate for weakness in deep knee flexion. These results suggest additional factors other than knee flexor muscle morphology play a role in knee flexion weakness following anterior cruciate ligament reconstruction with a distal semitendinosus tendon graft and thus more work at neural and microscopic levels is required for informing treatment and rehabilitation in this demographic.

Self-flocculation behaviour of cellulose-based bioflocculant synthesized from sewage water grown Chlorella sorokiniana and Scenedesmus abundans

The global energy crisis has spurred a shift from conventional to clean and sustainable energy sources. Biomass derived from microalgae is emerging as an alternative energy source with diverse applications. Despite the numerous advantages of microalgae, large-scale biomass harvesting is not economical and convenient. Self-flocculation is considered an effective phenomenon facilitated by extracting the flocculating substances from microalgae that assist aggregation of algal cells into flocs. A novel cellulose-based bioflocculant has been synthesized from sewage water grown Chlorella sorokiniana and Scenedesmus abundans for harvesting application. The produced bioflocculant amounted to 38.5% and 19.38% of the dry weight of S. abundans and C. sorokiniana, respectively. Analysis via FTIR, XRD, and FESEM-EDX revealed the presence of cellulose hydroxyapatite (HA) in algae-derived cellulose. Harvesting efficiencies of 95.3% and 89.16% were attained for S. abundans and C. sorokiniana, respectively, at a dosage of 0.5 g/L. Furthermore, the bioflocculant was recovered, enabling its reuse with recovery efficiencies of 52% and 10% for S. abundans and C. sorokiniana, respectively. This simple and efficient approach has the potential to replace other harvesting methods, thereby contributing to the economic algal biofuel production.

Biocompounds from wastewater-grown microalgae: a review of emerging cultivation and harvesting technologies

Microalgae biomass has attracted attention as a feedstock to produce biofuels, biofertilizers, and pigments. However, the high production cost associated with cultivation and separation stages is a challenge for the microalgae biotechnology application on a large scale. A promising approach to overcome the technical-economic limitations of microalgae production is using wastewater as a nutrient and water source for cultivation. This strategy reduces cultivation costs and contributes to valorizing sanitation resources. Therefore, this article presents a comprehensive literature review on the status of microalgae biomass cultivation in wastewater, focusing on production strategies and the accumulation of valuable compounds such as lipids, carbohydrates, proteins, fatty acids, and pigments. This review also covers emerging techniques for harvesting microalgae biomass cultivated in wastewater, discussing the advantages and limitations of the process, as well as pointing out the main research opportunities. The novelty of the study lies in providing a detailed analysis of state-of-the-art and potential advances in the cultivation and harvesting of microalgae, with a special focus on the use of wastewater and implementing innovative strategies to enhance productivity and the accumulation of compounds. In this context, the work aims to guide future research concerning emerging technologies in the field, emphasizing the importance of innovative approaches in cultivating and harvesting microalgae for advancing knowledge and practical applications in this area.

In vivo study to assess fat embolism resulting from the Reamer-Irrigator-Aspirator 2 system compared to a novel aspirator-based concept for intramedullary bone graft harvesting

INTRODUCTION

Fat embolism (FE) following intramedullary (IM) reaming can cause severe pulmonary complications and sudden death. Recently, a new harvesting concept was introduced in which a novel aspirator is used first for bone marrow (BM) aspiration and then for subsequent aspiration of morselized endosteal bone during sequential reaming (A + R + A). In contrast to the established Reamer-Irrigator-Aspirator (RIA) 2 system, the new A + R + A concept allows for the evacuation of fatty BM prior to reaming. In this study, we hypothesized that the risk of FE, associated coagulopathic reactions and pulmonary FE would be comparable between the RIA 2 system and the A + R + A concept.

MATERIALS AND METHODS

Intramedullary bone graft was harvested from intact femora of 16 Merino sheep (age: 1-2 years) with either the RIA 2 system (n = 8) or the A + R + A concept (n = 8). Fat intravasation was monitored with the Gurd test, coagulopathic response with D-dimer blood level concentration and pulmonary FE with histological evaluation of the lungs.

RESULTS

The total number and average size of intravasated fat particles was similar between groups (p = 0.13 and p = 0.98, respectively). D-dimer concentration did not significantly increase within 4 h after completion of surgery (RIA 2: p = 0.82; A + R + A: p = 0.23), with an interaction effect similar between groups (p = 0.65). The average lung area covered with fat globules was similar between groups (p = 0.17).

CONCLUSIONS

The use of the RIA 2 system and the novel A + R + A harvesting concept which consists of BM evacuation followed by sequential IM reaming and aspiration of endosteal bone, resulted in only minor fat intravasation, coagulopathic reactions and pulmonary FE, with no significant differences between the groups. Our results, therefore, suggest that both the RIA 2 system and the new A + R + A concept are comparable technologies in terms of FE-related complications.

Perspectives on cultivation and harvesting technologies of microalgae, towards environmental sustainability and life cycle analysis

The development of algae is seen as a potential and ecologically sound approach to address the increasing demands in multiple sectors. However, successful implementation of processes is highly dependent on effective growing and harvesting methods. The present study provides a complete examination of contemporary techniques employed in the production and harvesting of algae, with a particular emphasis on their sustainability. The review begins by examining several culture strategies, encompassing open ponds, closed photobioreactors, and raceway ponds. The analysis of each method is conducted in a systematic manner, with a particular focus on highlighting their advantages, limitations, and potential for expansion. This approach ensures that the conversation is in line with the objectives of sustainability. Moreover, this study explores essential elements of algae harvesting, including the processes of cell separation, dewatering, and biomass extraction. Traditional methods such as centrifugation, filtration, and sedimentation are examined in conjunction with novel, environmentally concerned strategies including flocculation, electro-coagulation, and membrane filtration. It evaluates the impacts on the environment that are caused by the cultivation process, including the usage of water and land, the use of energy, the production of carbon dioxide, and the runoff of nutrients. Furthermore, this study presents a thorough examination of the current body of research pertaining to Life Cycle Analysis (LCA) studies, presenting a perspective that emphasizes sustainability in the context of algae harvesting systems. In conclusion, the analysis ends up with an examination ahead at potential areas for future study in the cultivation and harvesting of algae. This review is an essential guide for scientists, policymakers, and industry experts associated with the advancement and implementation of algae-based technologies.

Effects of whaling and krill fishing on the whale-krill predation dynamics: bifurcations in a harvested predator-prey model with Holling type I functional response

In the Antarctic, the whale population had been reduced dramatically due to the unregulated whaling. It was expected that Antarctic krill, the main prey of whales, would grow significantly as a consequence and exploratory krill fishing was practiced in some areas. However, it was found that there has been a substantial decline in abundance of krill since the end of whaling, which is the phenomenon of krill paradox. In this paper, to study the krill-whale interaction we revisit a harvested predator-prey model with Holling I functional response. We find that the model admits at most two positive equilibria. When the two positive equilibria are located in the region{ ( N , P ) | 0 ≤ N < 2 N c , P ≥ 0 } , the model exhibits degenerate Bogdanov-Takens bifurcation with codimension up to 3 and Hopf bifurcation with codimension up to 2 by rigorous bifurcation analysis. When the two positive equilibria are located in the region{ ( N , P ) | N > 2 N c , P ≥ 0 } , the model has no complex bifurcation phenomenon. When there is one positive equilibrium on each side of N = 2 N c , the model undergoes Hopf bifurcation with codimension up to 2. Moreover, numerical simulation reveals that the model not only can exhibit the krill paradox phenomenon but also has three limit cycles, with the outmost one crosses the line N = 2 N c under some specific parameter conditions.

Modeling instream temperature from solar insolation under varying timber harvesting intensities using RPAS laser scanning

Stream temperatures are influenced by the amount of solar insolation they receive. Increasing stream temperatures associated with climate warming pose detrimental health risks to freshwater ecosystems. In British Columbia (BC), Canada, timber harvesting along forested streams is managed using riparian buffer zones of varying widths and designations. Within buffer zones, depending on distance from the stream, selective thinning may be permitted or harvest may be forbidden. In this study, we used airborne laser scanning (ALS) point cloud data acquired via a remotely piloted aircraft system (RPAS) to derive forest canopy characteristics that were then used to estimate daily incoming summer and fall solar insolation for five stream reaches in coastal conifer-dominated temperate forests in Vancouver Island, BC, Canada. We then examined empirical relationships between estimated insolation and actual instream temperature measurements. Based on these empirical relationships, the potential effects of timber harvest on instream temperatures were simulated by comparing scenarios of different riparian forest harvest intensities. Our results indicated that modeled solar insolation explained 43-90 % of the variation in observed stream reach temperatures, and furthermore, when a single cold-water stream reach was excluded explained an overall 81 % of variation. Simulated harvesting scenarios generally projected increases in maximum stream reach temperatures 1-2 °C in summer and early fall months. However, in a full clearcut scenario (i.e. where all trees were removed), maximum stream reach temperatures increased as much as 5.8 °C. Our results emphasize the importance of retaining riparian vegetation for the maintenance of habitable temperatures for freshwater-reliant fish with thermal restrictions. In addition, we demonstrate the feasibility of RPAS-based monitoring of stream reach shading and canopy cover, enabling detailed assessment of environmental stressors faced by fish populations under climate warming.

Clinging fauna associated with nearshore pelagic sargassum rafts in the Eastern Caribbean: Implications for coastal in-water harvesting

Tropical Atlantic blooms of pelagic Sargassum species are associated with severe inundation events along the coasts of Caribbean and West African nations that cause extensive ecological and socioeconomic harm. The use of in-water harvesting as a management strategy avoids the plethora of challenges associated with shoreline inundations. Moreover, with a growing interest in the valorisation of this raw material, in-water harvesting provides the best opportunity to collect substantial amounts of 'fresh' sargassum that can be used in a variety of applications. However, in-water harvesting of sargassum will remove organisms associated with the floating habitat, resulting in loss of biodiversity, thus creating a potential management dilemma. To address this management concern, we assessed the clinging fauna associated with sargassum rafts at various distances from shore. From a total of 119 dipnet samples of sargassum, we recorded 18 taxa, across 6 phyla (Arthropoda, Mollusca, Chordata, Platyhelminthes, Nemathelminthes, Annelida) with the phylum Arthropoda being the most speciose (n = 10). Our multivariate and model selection analyses support that distance from shore and season are the most important drivers of variability in community composition and that season is the most important driver of individual abundance and number of taxa across samples. Overall, rafts within 0-3000 m of the shoreline of Barbados harbored low biodiversity and were dominated by small invertebrates (mean size: 5.5 mm) of no commercial value. Results suggest that biodiversity trade-offs associated with in-water sargassum harvesting in coastal areas are likely to be negligible.

Eco-friendly microalgae harvesting using lipid-cored particles with a comparative life-cycle assessment

This study proposed an innovative approach using lipid-cored particles (LCPs) aimed at addressing the efficiency, cost, and environmental impact challenges in microalgae harvesting. Cetyltrimethylammonium bromide (CTAB) and chitosan (CS) were used to modify LCPs and to optimize efficiency and investigate the mechanisms of harvesting with Chlorella vulgaris. Results showed that a maximum harvesting efficiency of 97.14 % was achieved using CS-LCPs. Zeta potential and microscopic images revealed the presence of embedded CS-LCPs within microalgal flocs. Fractal dimension data suggested looser aggregates of CS-LCPs and Chlorella vulgaris, corroborated by Excitation-emission matrices (EEM) analysis further confirmation the presence of bridging networks. Moreover, life cycle assessment of five harvesting methods pointed freshwater ecotoxicity potential (FEP) and terrestrial ecotoxicity potential (TEP) as major environmental impacts, mainly from flocculant use, carrier production, and electricity consumption. Notably, LCPs showed the lowest global warming potential (GWP) at 1.54 kg CO2 eq, offering a viable, low-carbon, cost-effective harvesting alternative.

Advanced dual-artificial neural network system for biomass combustion analysis and emission minimization

Management of agricultural waste is an important part of plantation operations. Not all wastes are suitable for composting or the process is simply inefficient and time-consuming. In their case, thermal treatment is acceptable, but it is necessary to optimize the process to minimize greenhouse gas emissions. This article investigates the feasibility of constructing artificial neural networks (ANNs) to predict feedstock and emission parameters from the combustion of vineyard biomass. In order to maximize accuracy while avoiding overfitting of the ANN, a novel dual-ANN system was proposed. It consisted of two cascade-forward ANNs trained on independent data, each with three hidden layers. A benchmark showed that the final networks had a relative error in the range of 0.81-2.83%, and the resulting dual-ANN up to a maximum of 2.09%. Based on the ANN, it was possible to make recommendations on the parameters of the feedstock that would be suitable for obtaining bioenergy. It was noted that the best calorific values are shown by waste from plants with an intermediate amount, distribution, and mass of leaves, with relatively low average leaf area. Emissivity reduction, however, requires significantly different conditions. Preference is given to waste from plants that have high amounts of leaves but are spread over many stems - that is, plants that are highly shrubby during the growing season. This proves that it is not possible to formulate universal recommendations that are both energy- and carbon-beneficial, but outlines a clear direction where consensus should be sought, depending on the goals adopted.

High-efficiency harvesting of microalgae enabled by chitosan-coated magnetic biochar

Magnetic flocculation which uses magnetic particles is an emerging technology for harvesting microalgae. However, the potential modification and use of cost-effective and sustainable biochar-based composites is still in its infancy. As such, this study aimed to compare the harvesting efficiency of peanut shell biochar (BC), biochar modified with FeCl3 (FeBC), and biochar dual-modified with chitosan and FeCl3 (CTS@FeBC) on microalgae. The results showed CTS@FeBC exhibited significantly higher microalgae harvesting efficiency compared to BC and FeBC. Both acidic and alkaline conditions were favorable for harvesting microalgae by CTS@FeBC. At pH 2 and pH 12, the harvesting efficiency reached 96.9% and 98.8% within 2 min, respectively. The primary adsorption mechanism of CTS@FeBC on microalgae mainly involved electrostatic attraction and sweeping flocculation. Furthermore, CTS@FeBC also showed good biocompatibility and reusability. This study clearly demonstrated a promising technique for microalgae harvesting using biochar-based materials, offering valuable insights and potential applications in sustainable bioresource management.

Process for nutrient recycling from intensive aquaculture through microalgae-bacteria consortium

This work studies a biological process based on a microalgae-bacteria consortium for recycling nutrients in a recirculating aquaculture system (RAS) implanted in an intensive marine aquaculture farm. Additionally, some techniques were used for microalgae biomass harvesting and tested the effectiveness of filtration by a column with multi-layer sand to reduce the solids concentrations in the effluent. The consortium was grown in photobioreactors in batch and semi-continuous operation modes using the solids concentrated stream generated in the RAS system. The semi-continuous operation showed a high percentage of TDN and TDP removal, achieving final concentrations of 1.09 ± 0.02 mg·L-1 and 0.01 ± 0.01 mg·L-1, respectively, while DOC was reduced to 3.87 ± 0.06 mg·L-1. The values of productivity 44 ± 9 mg TSS·L-1 indicated that the studied stream is a suitable culture medium for the growth of the microalgae-bacteria consortium. A combination of harvesting techniques was studied, coagulation-flocculation-settling and coagulation-flocculation-flotation. The first step was to optimise the dose of FeCl3 through the coagulation-flocculation test to pre-concentrate the biomass generated, achieving an optimal dose of 0.106 mg Fe·mg TSS-1. Then, two separation processes were applied to the stream and compared: settling and flotation. The maximum removal efficiency (90.2 ± 0.3 %) was obtained in the settling process, so the coagulation-flocculation-settling was select as the best combination of harvesting techniques. Finally, sand filtration was studied as an effluent refining process to improve solids reduction of the water obtained in the harvesting step resulting in an effluent with 17.18 ± 1.49 mg TSS·L-1. The proposed sequence process is capable of recycling nutrients from an intensive marine aquaculture farm by using these resources via transformation into microalgae biomass and generating quality effluent.

Adjusting expected deaths for mortality displacement during the COVID-19 pandemic: a model based counterfactual approach at the level of individuals

BACKGROUND

Near-real time surveillance of excess mortality has been an essential tool during the COVID-19 pandemic. It remains critical for monitoring mortality as the pandemic wanes, to detect fluctuations in the death rate associated both with the longer-term impact of the pandemic (e.g. infection, containment measures and reduced service provision by the health and other systems) and the responses that followed (e.g. curtailment of containment measures, vaccination and the response of health and other systems to backlogs). Following the relaxing of social distancing regimes and reduction in the availability of testing, across many countries, it becomes critical to measure the impact of COVID-19 infection. However, prolonged periods of mortality in excess of the expected across entire populations has raised doubts over the validity of using unadjusted historic estimates of mortality to calculate the expected numbers of deaths that form the baseline for computing numbers of excess deaths because many individuals died earlier than they would otherwise have done: i.e. their mortality was displaced earlier in time to occur during the pandemic rather than when historic rates predicted. This is also often termed "harvesting" in the literature.

METHODS

We present a novel Cox-regression-based methodology using time-dependent covariates to estimate the profile of the increased risk of death across time in individuals who contracted COVID-19 among a population of hip fracture patients in England (N = 98,365). We use these hazards to simulate a distribution of survival times, in the presence of a COVID-19 positive test, and then calculate survival times based on hazard rates without a positive test and use the difference between the medians of these distributions to estimate the number of days a death has been displaced. This methodology is applied at the individual level, rather than the population level to provide a better understanding of the impact of a positive COVID-19 test on the mortality of groups with different vulnerabilities conferred by sociodemographic and health characteristics. Finally, we apply the mortality displacement estimates to adjust estimates of excess mortality using a "ball and urn" model.

RESULTS

Among the exemplar population we present an end-to-end application of our methodology to estimate the extent of mortality displacement. A greater proportion of older, male and frailer individuals were subject to significant displacement while the magnitude of displacement was higher in younger females and in individuals with lower frailty: groups who, in the absence of COVID-19, should have had a substantial life expectancy.

CONCLUSION

Our results indicate that calculating the expected number of deaths following the first wave of the pandemic in England based solely on historical trends results in an overestimate, and excess mortality will therefore be underestimated. Our findings, using this exemplar dataset are conditional on having experienced a hip fracture, which is not generalisable to the general population. Fractures that impede mobility in the weeks that follow the accident/surgery considerably shorten life expectancy and are in themselves markers of significant frailty. It is therefore important to apply these novel methods to the general population, among whom we anticipate strong patterns in mortality displacement - both in its length and prevalence - by age, sex, frailty and types of comorbidities. This counterfactual method may also be used to investigate a wider range of disruptive population health events. This has important implications for public health monitoring and the interpretation of public health data in England and globally.

An in vivo study to investigate an original intramedullary bone graft harvesting technology

BACKGROUND

Harvesting bone graft (BG) from the intramedullary canal to treat bone defects is largely conducted using the Reamer-Irrigator-Aspirator (RIA) system. The RIA system uses irrigation fluid during harvesting, which may result in washout of osteoinductive factors. Here, we propose a new harvesting technology dedicated to improving BG collection without the potential washout effect of osteoinductive factors associated with irrigation fluid. This novel technology involves the conceptual approach of first aspirating the bone marrow (BM) with a novel aspirator prototype, followed by reaming with standard reamers and collecting the bone chips with the aspirator (reaming-aspiration method, R-A method). The aim of this study was to assess the harvesting efficacy and osteoinductive profile of the BG harvested with RIA 2 system (RIA 2 group) compared to the novel harvesting concept (aspirator + R-A method, ARA group).

METHODS

Pre-planning computed tomography (CT) imaging was conducted on 16 sheep to determine the femoral isthmus canal diameter. In this non-recovery study, sheep were divided into two groups: RIA 2 group (n = 8) and ARA group (n = 8). We measured BG weight collected from left femur and determined femoral cortical bone volume reduction in postoperative CT imaging. Growth factor and inflammatory cytokine amounts of the BGs were quantified using enzyme-linked immunosorbent assay (ELISA) methods.

RESULTS

The use of the stand-alone novel aspirator in BM collection, and in harvesting BG when the aspirator is used in conjunction with sequential reaming (R-A method) was proven feasible. ELISA results showed that the collected BG contained relevant amounts of growth factors and inflammatory cytokines in both the RIA 2 and the ARA group.

CONCLUSIONS

Here, we present the first results of an innovative concept for harvesting intramedullary BG. It is a prototype of a novel aspirator technology that enables the stepwise harvesting of first BM and subsequent bone chips from the intramedullary canal of long bones. Both the BG collected with the RIA 2 system and the aspirator prototype had the capacity to preserve the BG's osteoinductive microenvironment. Future in vivo studies are required to confirm the bone regenerative capacity of BG harvested with the innovative harvesting technology.

Growth of Dunaliella viridis in multiple cycles of reclaimed media after repeated high pH-induced flocculation and harvesting

Minimizing the use of water for growing microalgae is crucial for lowering the energy and costs of animal feed, food, and biofuel production from microalgae. Dunaliella spp., a haloterant species that can accumulate high intracellular levels of lipids, carotenoids, or glycerol can be harvested effectively using low-cost and scalable high pH-induced flocculation. However, the growth of Dunaliella spp. in reclaimed media after flocculation and the impact of recycling on the flocculation efficiency have not been explored. In this study, repeated cycles of growth of Dunaliella viridis in repeatedly reclaimed media from high pH-induced flocculation were studied by evaluating cell concentrations, cellular components, dissolved organic matter (DOM), and bacterial community shifts in the reclaimed media. In reclaimed media, D. viridis grew to the same concentrations of cells and intracellular components as fresh media-107 cells/mL with cellular composition of 3 % lipids, 40 % proteins, and 15 % carbohydrates-even though DOM accumulated and the dominant bacterial populations changed. There was a decrease in the maximum specific growth rate and flocculation efficiency from 0.72 d-1 to 0.45 d-1 and from 60 % to 48 %, respectively. This study shows the potential of repeated (at least five times) flocculation and reuse of media as a possible way of reducing the costs of water and nutrients with some tradeoffs in growth rate and flocculation efficiency.

Biotechnologies for bulk production of microalgal biomass: from mass cultivation to dried biomass acquisition

Microalgal biomass represents a sustainable bioresource for various applications, such as food, nutraceuticals, pharmaceuticals, feed, and other bio-based products. For decades, its mass production has attracted widespread attention and interest. The process of microalgal biomass production involves several techniques, mainly cultivation, harvesting, drying, and pollution control. These techniques are often designed and optimized to meet optimal growth conditions for microalgae and to produce high-quality biomass at acceptable cost. Importantly, mass production techniques are important for producing a commercial product in sufficient amounts. However, it should not be overlooked that microalgal biotechnology still faces challenges, in particular the high cost of production, the lack of knowledge about biological contaminants and the challenge of loss of active ingredients during biomass production. These issues involve the research and development of low-cost, standardized, industrial-scale production equipment and the optimization of production processes, as well as the urgent need to increase the research on biological contaminants and microalgal active ingredients. This review systematically examines the global development of microalgal biotechnology for biomass production, with emphasis on the techniques of cultivation, harvesting, drying and control of biological contaminants, and discusses the challenges and strategies to further improve quality and reduce costs. Moreover, the current status of biomass production of some biotechnologically important species has been summarized, and the importance of improving microalgae-related standards for their commercial applications is noted.

Ecological Effects of Predator Harvesting and Environmental Noises on Oceanic Coral Reefs

Coral reefs provide refuge for prey and are important for the preservation of an oceanic ecosystem. However, they have been experiencing severe destruction by environmental changes and human activities. In this paper, we propose and analyze a tri-trophic food chain model consisting of coral, Crown-of-thorns starfish (CoTS), and triton in deterministic and stochastic environments. We investigate the effects of harvesting in the deterministic system and environmental noises in the stochastic system, respectively. The existence of possible steady states along with their stability is rigorously discussed. From the economic perspective, we examine the existence of the bionomic equilibrium and establish the optimal harvesting policy. Subsequently, the deterministic system is extended to a stochastic system through nonlinear perturbation. The stochastic system admits a unique positive global solution initiating from the interior of the positive quadrant. The long-time behaviors of the stochastic system are explored. Numerical simulations are provided to validate and complement our theoretical results. We show that over-harvesting of triton is not beneficial to coral reefs and modest harvesting of CoTS may promote sustainable growth in coral reefs. In addition, the presence of strong noises can lead to population extinction.

Bio-coatings as immobilized microalgae cultivation enhancement: A review

Bio-coatings serve as artificial scaffolds for immobilizing microalgae to facilitate cell concentration and harvesting. It has been used as an additional step to enhance the natural microalgal biofilm cultivation and to promote new opportunities in artificially-immobilize cultivation technology of microalgae. This technique is able to enhance biomass productivities, enable energy and cost saving, water volume reduction and ease of biomass harvesting since the cells are physically isolated from the liquid medium. However, scientific discoveries of bio-coatings for process intensification are still lacking and their working principles remained unclear. Therefore, this critical review aims to shed light on the advancement of cell encapsulation systems (hydrogel coating, artificial leaf, bio-catalytic latex coating, and cellular polymeric coating) over the years and aid in the selection of appropriate bio-coating techniques for various applications. Discussion on the different preparation routes of bio-coatings, as well as the exploration towards the potential of bio-based coating materials such as natural/synthetic polymers, latex binders, and algal organic matters are also included, with a focus on sustainable pursuits. This review also presents in-depth investigations into the environmental applications of bio-coatings in wastewater remediation, air purification, carbon bio-fixation, and bio-electricity. The field of bio-coating in microalgae immobilization gives rise to a new ecofriendly strategy with scalable cultivation footprint and a balanced environmental risk aligning with the United Nation's Sustainable Development Goals with potential towards the contribution of Zero Hunger, Clean Water and Sanitation, Affordable and Clean Energy, and Responsible Consumption and Production.

Dynamical properties of single species stage structured model with Michaelis-Menten type harvesting on adult population and linear harvesting on juvenile population

A very common and effective way for investigating future demographics is the study of stage structured models. The focus of this article is to propose a modified model to study the impact of population harvesting on their juvenile and adult stages, and analyze the dynamical properties from both qualitative and numerical perspective. It studies single species stage structured model with linear harvesting on juvenile group and Michaelis-Menten type harvesting on adult group. We exploit general ideas in mathematical modeling process to study the dynamical properties and their biological, ecological, and economic implications. It discusses that bi-stability phenomena may exist, global asymptotic stability at boundary equilibrium points and internal equilibrium points are investigated from construction of suitable Lyapunov and Dulac functions. It has been observed that a suitable linear harvesting on juvenile population can feasibly be carry out along with Michaelis-Menten type harvesting on adult population without endangering extinction of any group of population.

A Gender-Selective Harvesting Strategy: Weak Allee Effects and a Non-hyperbolic Extinction Boundary

Recently a gender-selective harvesting strategy has been proposed for possible control of aquatic invasive species, wherein females of the invasive species are harvested, whilst stocking the males (abbreviated as FHMS strategy) (Lyu et al. in Nat Resour Model 33(2):e12252, 2020). We consider the FHMS strategy with a weak Allee effect, and show that its extinction boundary need not be hyperbolic. To the best of our knowledge, this is the first example of a non-hyperbolic extinction boundary in two-compartment mating models structured by sex. The model possesses a rich dynamical structure, with several local co-dimension one bifurcations occurring. We also show the occurrence of a global homoclinic bifurcation, which has applicability for large scale strategic bio-control.

Effects of operational parameters on the performance of unialgal Oedogonium sp. filamentous algae nutrient scrubbers under controlled environmental conditions

Filamentous algae nutrient scrubber (FANS) operating parameters can strongly influence algal biomass productivity and nutrient removal. However, few studies to date have investigated the effects of FANS operating parameters such as initial standing crop, harvesting frequency and influent flow rate on biomass productivity and nutrient removal performance, especially for FANS that cultivate a single species of algae. Therefore, the overall aim of this study was to investigate how operating parameters affect the biomass productivity and nutrient removal performance of Oedogonium sp. - a promising species for unialgal FANS. The initial standing crop had a significant effect on biomass productivity, with productivities being highest (8.6 ± 0.5 g DW biomass m^-2day^-1) when the initial standing crop was 60-70 g DW m^-2. However, the daily nutrient removal rate was highest (0.47 ± 0.06 g N m^-2 day^-1and 1.24 ± 0.13 g P m^-2 day^-1) at the highest initial standing crop (100-110 DW m^-2). Biomass productivity was highest with a three-day growth period, regardless of size of the initial standing crop. Therefore, a four-day harvesting interval was selected as the optimal harvesting regime to promote exponential growth and high biomass production. Influent flow rate had a significant effect on biomass productivity, which was highest (9.3 ± 1.7 g DW m^-2 day^-1) for the 1 L min^-1 flow rate. This flow rate also gave the highest instantaneous nutrient removal rate (0.05 ± 0.02 g N m^-3 and 0.14 ± 0.05 g P m^-3). Current results suggest that an optimum initial standing crop of 70-80 g DW m^-2, harvesting frequency of four days and influent flow rate of 1 L min^-1 (16.7 L min^-1 m^-1 width) were optimal for Oedogonium sp. cultivated on FANS to maximize their biomass production and nutrient removal under controlled laboratory conditions. These results contribute to understanding the impacts of operating parameters on optimizing unialgal Oedogonium sp. FANS biomass production and nutrient removal performance.

Experience acquired after 34 years of the first heart transplantation in Mexico

On July 21, 1988, a successful heart transplant was carried out for the first time in Mexico; 34 years later, several hospitals in the country have performed this procedure. We present information and comments on the results obtained within this period at Mexican Social Security Institute La Raza National Medical Center "Dr. Gaudencio González Garza" General Hospital, where 234 transplants have been performed (one out of every three carried out throughout the country), with a short- and mid-term survival comparable to that reported in the rest of the world. This hospital is the only center that performs simultaneous heart-kidney transplantation and elective heart re-transplantation, with favorable results.

Nano magnetite assisted flocculation for efficient harvesting of lutein and lipid producing microalgae biomass

For commercial scale algal biorefining, harvesting cost is a major bottleneck. Thus, a cost-effective, less-energy intensive, and efficient harvesting method is being investigated. Among several harvesting methods, magnetic flocculation offers the benefits of modest operation, energy savings and quick separation. This study aims to develop novel magnetite-(Fe₃O₄) nanoparticles (MNPs) of 20 nm average size and their high reusability potential to reduce the harvesting cost of microalgae biomass. The MNPs were synthesized and characterized using FTIR, Zeta analyzer, and SEM before performing on Chlorella sorokiniana Kh12 and Tu5. For maximum harvesting efficiency >99%, the optimal culture pH, MNPs concentration, and agitation speed were 3, 200 mg/L, and 450 rpm, respectively. Subsequently, MNPs were recovered via alkaline treatment and reused up to 5 cycles as they retained their reactivity and harvesting efficiency. The studied MNPs-based harvesting method could be adopted at a commercial scale for cost-effective algae biorefinery in the future.

Air-liquid interface cultivation of Navicula incerta using hollow fiber membranes

Microalgae cultivation in open ponds requires a large footprint, while most photobioreactors need improvement in the ratio of surface to volume and energy consumption. In this study, polyethersulfone (PES) and poly(vinylidene fluoride) (PVDF) hollow fiber membranes with a large surface area were rearranged into open-ended and dead-ended configurations to improve the air-liquid interface cultivation of Navicula incerta. N. incerta were successfully grown on the porous membrane surface with the nutrients circulating inside the lumen. Fourier-transform infrared spectra showed the accumulation of polysaccharides, proteins and humic acids. Hydrophilic polysaccharides reduced water contact angles on PES and PVDF membranes to 37.2 ± 2.6° and 55.7 ± 3.3°, respectively. However, the porosity of PES (80.1 ± 1.1%) and PVDF (61.3 ± 4.5%) membranes were not significantly affected even after cultivation and harvesting of N. incerta. Scanning electron images further confirmed that N. incerta, cell debris and extracellular organic matter accumulated on the membrane. With large pores and a hydrophobic surface, PVDF hollow fiber membranes offered a greater improvement in N. incerta cell growth rate compared to PES hollow fiber membranes despite using different configurations. In the dead-ended configuration, they even attained the greatest improvement in N. incerta growth rate, up to 54.0%. However, PES hollow fiber membranes only achieved improvement in harvesting efficiency within the range of 18.7-38.0% due to weak cell adhesion. PVDF hollow fiber membranes significantly promoted the growth of microalgae N. incerta through the air-liquid interface system, leading to potential applications in wastewater treatment.

Vegetation height and structure drive foraging habitat selection of the lesser kestrel (Falco naumanni) in intensive agricultural landscapes

Habitat selection in animals is a fundamental ecological process with key conservation implications. Assessing habitat selection in endangered species and populations occupying the extreme edges of their distribution range, or living in highly anthropized landscapes, may be of particular interest as it may provide hints to mechanisms promoting potential range expansions. We assessed second- and third-order foraging habitat selection in the northernmost European breeding population of the lesser kestrel (Falco naumanni), a migratory falcon of European conservation interest, by integrating results obtained from 411 direct observations with those gathered from nine GPS-tracked individuals. The study population breeds in the intensively cultivated Po Plain (northern Italy). Direct observations and GPS data coincide in showing that foraging lesser kestrels shifted their habitat preferences through the breeding cycle. They positively selected alfalfa and other non-irrigated crops during the early breeding season, while winter cereals were selected during the nestling-rearing phase. Maize was selected during the early breeding season, after sowing, but significantly avoided later. Overall, vegetation height emerged as the main predictor of foraging habitat selection, with birds preferring short vegetation, which is likely to maximise prey accessibility. Such a flexibility in foraging habitat selection according to spatio-temporal variation in the agricultural landscape determined by local crop management practices may have allowed the species to successfully thrive in one of the most intensively cultivated areas of Europe. In the southeastern Po Plain, the broad extent of hay and non-irrigated crops is possibly functioning as a surrogate habitat for the pseudo-steppe environment where most of the European breeding population is settled, fostering the northward expansion of the species in Europe. In intensive agricultural landscapes, the maintenance of alfalfa and winter cereals crops and an overall high crop heterogeneity (deriving from crop rotation) is fundamental to accommodate the ecological requirements of the species in different phases of its breeding cycle.

Current perspective on wastewater treatment using photobioreactor for Tetraselmis sp.: an emerging and foreseeable sustainable approach

Urbanization is a revolutionary and necessary step for the development of nations. However, with development emanates its drawback i.e., generation of a huge amount of wastewater. The existence of diverse types of nutrient loads and toxic compounds in wastewater can reduce the pristine nature of the ecosystem and adversely affects human and animal health. The conventional treatment system reduces most of the chemical contaminants but their removal efficiency is low. Thus, microalgae-based biological wastewater treatment is a sustainable approach for the removal of nutrient loads from wastewater. Among various microalgae, Tetraselmis sp. is a robust strain that can remediate industrial, municipal, and animal-based wastewater and reduce significant amounts of nutrient loads and heavy metals. The produced biomass contains lipids, carbohydrates, and pigments. Among them, carbohydrates and lipids can be used as feedstock for the production of bioenergy products. Moreover, the usage of a photobioreactor (PBR) system improves biomass production and nutrient removal efficiency. Thus, the present review comprehensively discusses the latest studies on Tetraselmis sp. based wastewater treatment processes, focusing on the use of different bioreactor systems to improve pollutant removal efficiency. Moreover, the applications of Tetraselmis sp. biomass, advancement and research gap such as immobilized and co-cultivation have also been discussed. Furthermore, an insight into the harvesting of Tetraselmis biomass, effects of physiological, and nutritional parameters for their growth has also been provided. Thus, the present review will broaden the outlook and help to develop a sustainable and feasible approach for the restoration of the environment.

Minimally invasive left internal mammary artery harvesting techniques during the learning curve are safe and achieve similar results as conventional LIMA harvesting techniques

Background

Internal thoracic arteries (ITAs) are considered to be the standard conduits used for coronary revascularization. Recently minimally invasive procedures are performed to harvest ITAs. The aim of this retrospective cohort study is to observe the effect and safety of less invasive LIMA harvesting approaches in the learning curve compared to conventional harvesting.

Methods

We retrospectively analyzed the data of 138 patients divided into three different groups based on the LIMA harvesting techniques: conventional sternotomy LIMA harvesting, CSLH (n: 64), minimally invasive direct LIMA harvesting, MIDLH (n: 42), and robotic-assisted LIMA harvesting, RALH (n: 32). The same 138 patients were also divided into sternotomy (n: 64), and non-sternotomy (n: 74) groups keeping both MIDLH and RALH in the non-sternotomy category. Parameters associated with LIMA’s quality and some other perioperative parameters such as harvesting time, LIMA damage, perioperative myocardial infarction, ventilation time, 24 h drainage, ICU stay, hospital mortality, computed tomographic angiography (CTA) LIMA patency on discharge, and after one year were recorded.

Results

The mean LIMA harvesting time was 36.9 ± 14.3, 74.4 ± 24.2, and 164.7 ± 51.9 min for CSLH, MIDLH, and RALH groups respectively (p < 0.001). One patient 1/32 (3.1%) in the RALH group had LIMA damage while the other two groups had none. One-month LIMA CTA patency was 56/57 (98.2%), 34/36 (94.4%), and 27/27 (100%) (p = 0.339), while 1 year CTA patency was 47/51 (92.1%), 30/33 (90.9%), and 24/25 (96%) for CSLH, MIDLH, and RALH groups respectively (p = 0.754). In the case of sternotomy vs non-sternotomy, the LIMA harvesting time was 36.9 ± 14.3 and 113.6 ± 59.3 min (p < 0.001). CTA patency on discharge was 56/57 (98.2%) and 61/63 (96.8%) (p = 0.619), while 1 year CTA patency was 47/51 (92.1%) and 54/58 (93.1%) (p = 0.850) for sternotomy vs non-sternotomy groups.

Conclusion

Minimally invasive left internal mammary artery harvesting techniques during the learning curve are safe and have no negative impact on the quality of LIMA. Perioperative outcomes are comparable to conventional procedures except for prolonged harvesting time. RALH is the least invasive and most time-consuming procedure during the learning curve. These procedures are safe and can be performed for selected patients even during the learning curve.

Microalgal flocculation and sedimentation: spatiotemporal evaluation of the effects of the pH and calcium concentration

The high cost of harvesting microalgae is a major hurdle for the microalgae industry, and an efficient pre-concentration method is required. In this study, the effects of using different pH values (between pH 3 and 11) and calcium (Ca²⁺) concentrations (between 0 and 5 mM) on Chlorella vulgaris sedimentation were investigated by evaluating the spacio-temporal distributions of microalgae cells. Fast and efficient sedimentation occurred (within 10 min) at a high Ca²⁺ concentration (5 mM) at pH 9 and 11. However, the sediment volume was lower at a Ca²⁺ concentration of 3 mM than at a Ca²⁺ concentration of 5 mM. This indicated that the Ca²⁺ concentration strongly affected the sediment volume. Fast sedimentation and a low sediment volume were found at pH 7 and a Ca²⁺ concentration of 5 mM, probably because of the neutral charge in the system (adhesion to calcium precipitates would have occurred at a high pH). The highest Ca²⁺ recovery (82%) was achieved when sediment produced at pH 11 and a Ca²⁺ concentration of 5 mM was acidified to pH 3.

Micro-algae assisted green bioremediation of water pollutants rich leachate and source products recovery

Water management and treatment are high concern fields with several challenges due to increasing pollutants produced by human activity. It is imperative to find integral solutions and strategic measures with robust remediation. Landfill leachate production is a high concern emerging problem. Especially in low middle-income countries due to no proper local waste disposition regulation and non-engineered implemented methods to dispose of urban waste. These landfills can accumulate electronic waste and release heavy metals during the degradation process. Similar phenomena include expired pharmaceuticals like antibiotics. All these pollutants accumulated in leachate made it hard to dispose of or treat. Leachate produced in non-engineered landfills can permeate soils and reach groundwater, dragging different contaminants, including antibiotics and heavy metals, which eventually can affect the environment, changing soil properties and affecting wildlife. The presence of antibiotics in the environment is a problem with particular interest to solve, mainly to avoid the development of antibiotic-resistant microorganisms, which represent a future risk for human health with possible epidemic implications. It has been reported that the use of contaminated water with heavy metals to produce and grow vegetables is a risk for consumers, heavy metals effects in humans can include carcinogenic induction. This work explores the opportunities to use leachate as a source of nutrients to grow microalgae. Microalgae stand out as an alternative to bioremediate leachate, at the same time, microalgae produce high-value compounds that can be used in bioplastic, biofuels, and other industrial applications.

Spatio-temporal solutions of a diffusive directed dynamics model with harvesting

The study considers a directed dynamics reaction-diffusion competition model to study the density of evolution for a single species population with harvesting effect in a heterogeneous environment, where all functions are spatially distributed in time series. The dispersal dynamics describe the growth of the species, which is distributed according to the resource function with no-flux boundary conditions. The analysis investigates the existence, positivity, persistence, and stability of solutions for both time-periodic and spatial functions. The carrying capacity and the distribution function are either arbitrary or proportional. It is observed that if harvesting exceeds the growth rate, then eventually, the population drops down to extinction. Several numerical examples are considered to support the theoretical results.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12190-022-01742-x.

Recent Development of Morphology-Controlled Hybrid Nanomaterials for Triboelectric Nanogenerator: A Review

Being cognizant of modern electronic devices, the scientists are continuing to investigate renewable green-energy resources for a decade. Amid different energy harvesting systems, the triboelectric nanogenerators (TENGs) have been found to be the most promising mechanical harvesting technology and have drawn attention to generate electrical energy. Thanks to its instant output power, choice to opt for wide-ranging materials, low maintenance cost, easy fabrication process and environmentally friendly nature. Due to numerous working modes of TENGs, it is dedicated to desired application at ambient conditions. In this review, an advance correlation of TENGs have been explained based on the variety of nanostructures, including 0D, 1D, 2D, 3D, metal organic frameworks (MOFs), coordination polymers (CPs), covalent organic frameworks (COFs), and perovskite materials. Moreover, an overview of previous and current perspectives of various nanomaterials, synthesis, fabrication and their applications in potential fields have been discussed in detail.

The response of geophytes to continuous human foraging on the Cape south coast, South Africa and its implications for early hunter-gatherer mobility patterns

Current ecological understanding of plants with underground storage organs (USOs) suggests they have, in general, low rates of recruitment and thus as a resource it should be rapidly exhausted, which likely had implications for hunter-gatherer mobility patterns. We focus on the resilience (defined here as the ability of species to persist after being harvested) of USOs to human foraging. Human foragers harvested all visible USO material from 19 plots spread across six Cape south coast (South Africa) vegetation types for three consecutive years (2015-2017) during the period of peak USO apparency (September-October). We expected the plots to be depleted after the first year of harvesting since the entire storage organ of the USO is removed during foraging, i.e. immediate and substantial declines from the first to the second harvest. However, over 50% of the total weight harvested in 2015 was harvested in 2016 and 2017; only after two consecutive years of harvesting, was there evidence of significantly lower yield (p = 0.034) than the first (2015) harvest. Novel emergence of new species and new individuals in year two and three buffered the decline of harvested USOs. We use our findings to make predictions on hunter-gatherer mobility patterns in this region compared to the Hadza in East Africa and the Alyawara in North Australia.

The effects of random and seasonal environmental fluctuations on optimal harvesting and stocking

We analyze the harvesting and stocking of a population that is affected by random and seasonal environmental fluctuations. The main novelty comes from having three layers of environmental fluctuations. The first layer is due to the environment switching at random times between different environmental states. This is similar to having sudden environmental changes or catastrophes. The second layer is due to seasonal variation, where there is a significant change in the dynamics between seasons. Finally, the third layer is due to the constant presence of environmental stochasticity-between the seasonal or random regime switches, the species is affected by fluctuations which can be modelled by white noise. This framework is more realistic because it can capture both significant random and deterministic environmental shifts as well as small and frequent fluctuations in abiotic factors. Our framework also allows for the price or cost of harvesting to change deterministically and stochastically, something that is more realistic from an economic point of view. The combined effects of seasonal and random fluctuations make it impossible to find the optimal harvesting-stocking strategy analytically. We get around this roadblock by developing rigorous numerical approximations and proving that they converge to the optimal harvesting-stocking strategy. We apply our methods to multiple population models and explore how prices, or costs, and environmental fluctuations influence the optimal harvesting-stocking strategy. We show that in many situations the optimal way of harvesting and stocking is not of threshold type.

Tannin-based coagulant for harvesting microalgae cultivated in wastewater: Efficiency, floc morphology and products characterization

Tannin-based coagulants (TBCs) have the potential to be used to harvest microalgae cultivated at wastewater treatment plants. Their use would address the circular economy associated with the production of low-toxicity biomass and supernatant. Studies in this field are still scarce, and substantial gaps exist in the definitions of the flocculation process parameters. In this context, the objective of this work was to evaluate TBC performance as a natural coagulant for harvesting microalgae biomass grown in sanitary effluent digested in an up flow biofilter, as well establishing a path to enable recovery and reuse of wastewater nutrients. Classical removal techniques combined with image analysis and light scattering-based equipment were used to evaluate the coagulant performance, recovery efficiency, floc strength, and floc recovery compared to aluminum sulfate (AS). The results showed that TBC was able to efficiently harvest algal biomass from the effluent, achieving color, turbidity, and optical density (OD) removal efficiencies greater than 90% with only 5 min of sedimentation. The optimal harvesting dosage was 100 mg·L^-1 for TBC and 75 mg·L^-1 for AS. TBC presented the advantage of harvesting biomass without changing the pH of the medium and was also able to present satisfactory removal of the analyzed parameters (color, turbidity and OD) at pH values of 5.0, 7.0, and 8.5. In addition, TBC produced stronger flocs than AS, showing a better ability to resist breakage upon sudden shear rate variations. TBC produced macronutrient-rich biomass and supernatant that was similar to that produced with AS.

RIA versus iliac crest bone graft harvesting: A meta-analysis and systematic review

BACKGROUND

Reamer-Irrigator-Aspirator (RIA) of long bones is increasingly being used as an alternative to iliac crest harvesting for bone-grafts. This meta-analysis compares both harvesting techniques with regard to donor site morbidity, healing potency and implantation site morbidity.

METHODS

PubMed/Medline/Embase/CENTRAL/CINAHL were searched for both randomized clinical trials (RCT) and observational studies. Effect estimates were pooled across studies using random effects models and presented as weighted odds ratio (OR) with corresponding 95% confidence interval (95%CI).

RESULTS

A total of 5 studies were included. RIA carries a lower risk for chronic pain (0% versus 14.2%, OR 0.08, 95% CI 0.02 - 0.35) and infection (1% versus 5.9%, OR 0.29, 95% CI 0.09- 0.9) at the donor site compared to iliac crest harvesting. Iliac crest bone-harvesting has an inherent additional risk of neuropraxia of the lateral femoral cutaneous nerve and numbness of the scar which is not encountered in RIA harvesting. Risk for other reported complications such as hematoma and iatrogenic fractures appear equal in both groups. The clinical healing potential of both bone grafts, in terms of union rate (OR 1.53, 95%CI 0.62 - 3.75) at the implantation site and time-to-union (MD 0.44 months, 95%CI -1.72 - 0.83), seems equal.

CONCLUSION

The main difference between RIA and iliac crest bone graft harvesting is the considerable higher risk of chronic pain of the pelvic procedure. Although risk for infection was also higher for the iliac crest group, the absolute difference is relatively small. Evidence suggests an equal healing potential of the grafts themselves irrespective of harvesting method.

Evaluation of an outdoor pilot-scale tubular photobioreactor for removal of selected pesticides from water

This work assesses the capacity of a microalgae-based system to remove three highly to medium polar pesticides typically found in freshwater: acetamiprid, bentazone, and propanil. Degradation of the pesticides was firstly studied individually at batch lab-scale reactors and abiotic and heated-killed controls were employed to clarify their removal pathways. At lab-scale, propanil and acetamiprid were completely removed after 7 days whereas bentazone was not removed. Four and two transformation products (TPs) were generated in the biodegradation process for acetamiprid and propanil, respectively. Then, the simultaneous removal of the pesticides was assessed in an outdoor pilot photobioreactor, operated with a hydraulic residence time of 8 days. During the steady-state, high removal efficiencies were observed for propanil (99%) and acetamiprid (71%). The results from batch experiments suggest that removal is mainly caused by algal-mediated biodegradation. Acetamiprid TPs raised throughout the operational time in the photobioreactor, while no propanil TP was detected at the pilot-scale. This suggests complete mineralization of propanil or residual formation of its TPs at concentrations below the analytical method detection limit. Aiming at biomass valorization, diverse microalgae harvesting methods were investigated for biomass concentration, and the effect of residual pesticides on the biogas yield was determined by biochemical methane potential tests. Anaerobic digestion was not inhibited by the pesticides as verified by the digestion performance. The results highlight the potential of microalgae-based systems to couple nutrient removal, biomass production, micropollutant biodegradation, and biofuel production.

Nannochloropsis oceanica harvested using electrocoagulation with alternative electrodes - An innovative approach on potential biomass applications

Electrocoagulation is a promising technology to harvest microalgal biomass. However, the commonly used aluminum electrodes release undesired salts that decrease biomass value. In this study, alternative iron, zinc, and magnesium electrodes and operational parameters pH, time and current density were studied to harvest Nannochloropsis oceanica. For recovery efficiency and concentration factor the initial pH was most important using iron electrodes, while time and current density were more relevant using zinc and magnesium electrodes. Optimal parameters resulted in biomass recovery efficiencies > 95%, biomass was concentrated 2.8-7.2 times and contained 15.7-29.1% ashes. Elemental analysis revealed metal salts in harvested biomass resulting from electrode corrosion. Finally, ash contents could be reduced by 65% using EDTA as a chelating agent. The electrocoagulation harvested microalgal biomass enriched in essential metals may be a promising bioresource for agricultural growth inducers, or functional ingredients for feed.

Recent progress in flocculation, dewatering, and drying technologies for microalgae utilization: Scalable and low-cost harvesting process development

Microalgal research has made significant progress in terms of the high-value-added industrial application of microalgal biomass and its derivatives. However, cost-effective techniques for producing, harvesting, and processing microalgal biomass on a large scale still need to be fully explored in order to optimize their performance and achieve commercial robustness. In particular, technologies for harvesting microalgae are critical in the practical process as they require excessive energy and equipment costs. This review focuses on microalgal flocculation, dewatering, and drying techniques and specifically covers the traditional approaches and recent technological progress in harvesting microalgal biomass. Several aspects, including the characteristics of the target microalgae and the type of final value-added products, must be considered when selecting the appropriate harvesting technique. Furthermore, considerable aspects and possible future directions in flocculation, dewatering, and drying steps are proposed to develop scalable and low-cost microalgal harvesting systems.

Mass cultivation and harvesting of microalgal biomass: Current trends and future perspectives

Microalgae are unicellular photosynthetic organisms capable of producing high-value metabolites like carbohydrates, lipids, proteins, polyunsaturated fatty acids, vitamins, pigments, and other high-value metabolites. Microalgal biomass gained more interest for the production of nutraceuticals, pharmaceuticals, therapeutics, food supplements, feed, biofuel, bio-fertilizers, etc. due to its high lipid and other high-value metabolite content. Microalgal biomass has the potential to convert trapped solar energy to organic materials and potential metabolites of nutraceutical and industrial interest. They have higher efficiency to fix carbon dioxide (CO₂) and subsequently convert it into biomass and compounds of potential interest. However, to make microalgae a potential industrial candidate, cost-effective cultivation systems and harvesting methods for increasing biomass yield and reducing the cost of downstream processing have become extremely urgent and important. In this review, the current development in different microalgal cultivation systems and harvesting methods has been discussed.

All we need to know about internal thoracic artery harvesting and preparation for myocardial revascularization: a systematic review

Internal thoracic arteries (ITAs) are the gold standard conduits for coronary revascularization because of their long-term patency and anti-atherosclerotic properties. Harvesting and preparation of ITAs for revascularization is a technically demanding procedure with multiple challenges. Over the last few decades, various methods and techniques for ITAs harvesting have been introduced by different surgeons and applied in clinical practice with different results. Harvesting of ITAs in pedicled or skeletonized fashion, with electrocautery or harmonic scalpel, with open or intact pleura, with clipping the end or keeping it perfused; papaverine delivery with intraluminal injection, perivascular injection, injecting into endothoracic fascia, and papaverine topical spray are the different techniques introduced by the number of researchers. At the same time, access to the ITAs for harvesting has also been studied. Access and harvesting through median sternotomy, mini anterolateral thoracotomy, thoracoscopic, and robotic-assisted harvesting of ITAs are the different techniques used in clinical practice. However, the single standard method for harvesting and preparation of ITAs has yet to be determined. In this review article, we aimed to discuss and analyze all these techniques of harvesting and preparing ITAs with the help of literature to find the best way for ITAs harvesting and preparation for myocardial revascularization.

A critical review on different harvesting techniques for algal based biodiesel production

The fuels retrieved from renewable sources which are usually employed as both carbon and energy sources are termed as neutral based biofuels. The most promising feedstock from renewable sources with great potentiality in contributing to the inclining energy demand is microalgae. These microalgae can be harnessed readily in terms of obtaining qualitative biodiesel with greater energy consumption under limited operational cost. The process of harvesting or dewatering microalgae could be carried under single or sequential combinations of operations. The major drawback of harvesting such as huge operational cost could be lowered by increasing the level of automation than cost of investments. The present review concentrates and explores on the techno-economic analysis of the microalgal harvesting and dewatering processes on a large scale. Along with these advanced techniques enclosing the utilization of nanoparticles for harvesting has also been explored. And it also adds with the impacts of concerning facts on energy consumption, processing cost and recovery of resources during harvesting.

A strategic approach to apply bacterial substances for increasing metabolite productions of Euglena gracilis in the bioreactor

Bacterial extracellular polymeric substances (EPS) are promising materials that have a role in enhancing growth, metabolite production, and harvesting efficiency. However, the validity of the EPS effectiveness in scale-up cultivation of microalgae is still unknown. Therefore, in order to verify whether the bacterial metabolites work in the scale-up fermentation of microalgae, we conducted a bioreactor fermentation following the addition of bacterial EPS derived from the marine bacterium, Pseudoalteromonas sp., to Euglena gracilis. Various culture strategies (i.e., batch, glucose fed-batch, and glucose and EPS fed-batch) were conducted to maximize metabolite production of E. gracilis in scale-up cultivation. Consequently, biomass and paramylon concentrations in the continuous glucose and EPS-treated culture were enhanced by 3.0-fold and 4.2-fold (36.1 ± 1.4 g L^-1 and 25.6 ± 0.1 g L^-1), respectively, compared to the non-treated control (12.0 ± 0.3 g L^-1 and 6.1 ± 0.1 g L^-1). Also, the supplementation led to the enhanced concentrations of α-tocopherols and total fatty acids by 3.7-fold and 2.8-fold, respectively. The harvesting efficiency was enhanced in EPS-supplemented cultivation due to the flocculation of E. gracilis. To the best of our knowledge, this is the first study that verifies the effect of bacterial EPS in scale-up cultivation of microalgae. Also, our results showed the highest paramylon productivity than any other previous reports. The results obtained in this study showed that the scale-up cultivation of E. gracilis using bacterial EPS has the potential to be used as a platform to guide further increases in scale and in the industrial environment. KEY POINTS: Effect of EPS on Euglena gracilis fermentation was tested in bioreactor scale. EPS supplement was effective for the paramylon, α-tocopherol, and lipid production. EPS supplement induced the flocculation of E. gracilis.

Microalgal bio-flocculation: present scenario and prospects for commercialization

The need for sustainable production of renewable biofuel has been a global concern in the recent times. Overcoming the tailbacks of the first- and second-generation biofuels, third-generation biofuel using microalgae as feedstock has emerged as a plausible alternative. It has an added advantage of preventing any greenhouse gas (GHG) emissions with simultaneous carbon dioxide sequestration. Dewatering of microalgal culture is one of the many concerns regarding industrial-scale biofuel production. The small size of microalgae and dilute nature of its growth cultures creates huge operational cost during biomass separation, limiting economic feasibility of algae-based fuels. Considering the recovery efficiency, operation economics, technological feasibility and cost-effectiveness, bio-flocculation is a promising method of harvesting. Moreover, advantage of bio-flocculation over other conventional methods is that it does not incur the addition of any external chemical flocculants. This article reviews the current status of bio-flocculation technique for harvesting microalgae at industrial scale. The various microbial strains that can be prospective bioflocculants have been reviewed along with its application and advantages over chemical flocculants. Also, this article proposes that the primary focus of an appropriate harvesting technique should depend on the final utilization of the harvested biomass. This review article attempts to bring forth the beneficial aspects of microbial aided microalgal harvesting with a special attention on genetically modified self-flocculation microalgae.

Simulation of the effects of forest harvesting under changing climate to inform long-term sustainable forest management using a biogeochemical model

Process ecosystem models are useful tools to provide insight on complex, dynamic ecological systems, and their response to disturbances. The biogeochemical model PnET-BGC was modified and tested using field observations from an experimentally whole-tree harvested northern hardwood watershed (W5) at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA. In this study, the confirmed model was used as a heuristic tool to investigate long-term changes in hydrology, biomass accumulation, and soil solution and stream water chemistry for three different watershed cutting intensities (40%, 60%, 80%) and three rotation lengths (30, 60, 90 years) under both constant (current climate) and changing (MIROC5-RCP4.5) future climate scenarios and atmospheric CO₂ through the year 2200. For the no future cutting scenario, total ecosystem stored carbon (i.e., sum of aboveground biomass, woody debris and soil) reached a maximum value of 207 t C ha^-1 under constant climate but increased to 452 t C ha^-1 under changing climate in 2200 due to a CO₂ fertilization effect. Harvesting of trees decreased total ecosystem stored carbon between 7 and 36% for constant climate and 7-60% under changing climate, respectively, with greater reductions for shorter logging rotation lengths and greater watershed cutting intensities. Harvesting under climate change resulted in noticeable losses of soil organic matter (12-56%) coinciding with loss of soil nutrients primarily due to higher rates of soil mineralization associated with increases in temperature, compared with constant climate conditions (3-22%). Cumulative stream leaching of nitrate under climate change (181-513 kg N ha^-1) exceeded constant climate values (139-391 kg N ha^-1) for the various cutting regimes. Under both climate conditions the model projected greater sensitivity to varying the length of cutting period than cutting intensities. Hypothetical model simulations highlight future challenges in maintaining long-term productivity of managed forests under changing climate due to a potential for a deterioration of soil fertility.

Harvesting freshwater algae with tannins from the bark of forest species: Comparison of methods and pelletization of the biomass obtained

Toxic cyanobacteria growth rates have increased in recent decades due to climate change and human activities. Microalgae, with their ability to produce a large amount of biomass, are considered as a source of energy that can be used to produce biofuels. The aim of this study is to test four different microalgae harvesting methods (sedimentation, coagulation-flocculation, pH variation, and centrifugation) in order to find which is best suited to the A Baxe reservoir, which has been suffering from cyanobacterial blooms in recent years. Centrifugation proved the most efficient method (85.74%-1790 RCF), but it can induce cell rupture. Natural sedimentation and pH variation obtained similar results at 49.36% and 49.02% respectively. Although all four methods have advantages, our results reveal that coagulation-flocculation, using 10 mg/L of Pinus pinaster, results in a removal efficiency of 68.10%, making it the most suitable method, though with 20 mg/L the performance was lower (66.03%). To minimise environmental waste, the microalgae removed were then transformed into pellets to be used as biofuel, with a higher heating value (HHV) of 21,196.96 ± 1602.33 kJ/kg. The pellets obtained from the microalgae residue did not meet all the requirements for use as biofuels, but microalgae biomass could be mixed with other sources and therefore looks like a promising option for the future.

Robotic-assisted harvest of latissimus dorsi muscle flap for breast reconstruction: review of the literature

Robotic-assisted surgery continues to gain ground over conventional surgical methods, due to reported better results regarding the aesthetic outcome and the decreased percentage of complications. Although latissimus dorsi flap harvesting for breast reconstruction has been already used for several years, a plethora of serious complications has been reported. Recently, minimally invasive surgical approaches, such as robotic-assisted technique, have been suggested with conflicting outcomes to overcome technical difficulties. Therefore, the literature review was conducted regarding robotic-assisted harvesting of the latissimus dorsi flap for breast reconstruction. A narrative review of the contemporary literature was performed in the PubMed database for the use of robotic-assisted surgery of latissimus dorsi muscle flap harvesting for breast reconstruction. Appropriate search terms were used, and specific inclusion and exclusion criteria were applied. Five studies met the inclusion criteria. A total of 32 cases of robotically assisted harvesting of pedicled latissimus dorsi muscle flap for implant-based breast reconstruction have been identified. All flaps were successfully harvested without converting in the traditional open procedure. There were no significant postoperative complications, expect from few cases of postoperative seromas, which were conservatively managed. Additionally, all patients were satisfied with their postoperative cosmetic outcome. The robotic-assisted harvesting technique of the latissimus dorsi flap for breast reconstruction is safe and comparable to the conventional methods. Reduced hospital stays and superior aesthetic outcome are the main advantages, while total cost and the difficulty of reaching the learning curve plateau are the main concerns regarding this modern and minimally invasive surgical approach.

Electrocoagulation reduces harvesting costs for microalgae

Centrifugation is the most commonly used method for harvesting autotrophically produced microalgae, but it is expensive due to high energy demands. With the aim of reducing these costs, we tested electrocoagulation with iron electrodes for harvesting Chlorella vulgaris. During extensive lab-scale experiments, the following factors were studied to achieve a high harvesting efficiency and a low iron content in the harvested biomass: electric charge, initial biomass concentration, pH, temperature, agitation intensity, residual salt content and electrolysis time. A harvesting efficiency greater than 95% was achieved over a broad range of conditions and the residual iron content in the biomass complied with legislative requirements for food. Using electrocoagulation as the pre-concentration step prior to centrifugation, total energy costs were reduced to 0.136 kWh/kg of dry biomass, which is less than 14% of that for centrifugation alone. Our data show that electrocoagulation is a suitable and cost-effective method for harvesting microalgae.

Phosphorus removal in a pilot scale free water surface constructed wetland: hydraulic retention time, seasonality and standing stock evaluation

Constructed wetlands (CWs) are decentralized wastewater treatment systems considered to be green and low cost. They have the potential to effectively remove pollutants and recycle nutrients with plant composting. However, they need large areas to implement them due to the usual high Hydraulic Retention Times (HRT), reaching up to 50 days. The main objective of the present study was to evaluate the influence of HRT (HRT = 3, 7, and 10 days), and seasonality on Total Phosphorus (TP) removal, and standing stock in a pilot scale free water surface CW (FWS CW). Unplanted and planted (Eichhornia crassipes) tanks were evaluated in wet and dry seasons. The FWS CW was set up as a complementary treatment to a secondary level wastewater treatment plant. The system was monitored weekly for ten months, totalizing 29 replicate samplings (n = 58). Planted tanks were harvested every week to keep free space for plant reproduction (∼40%). The mean removal efficiency of TP ranged between 82% and 95% without a significant difference between HRT (p_value > 0.05). However, when the effects of the sedimentation of the unplanted tanks were disregarded, the lowest HRT (3 days) tank presented the highest standing stock of TP. The wet season presented a significant difference in TP removal results (p_value < 0.05), associated with higher macrophyte growth rate due to more intense solar irradiation and incorporation of TP by E. crassipes. The results point out advances in P removal and recycling by a low-cost ecological engineering system.