Insight into soft chemometric computational learning for modelling oily-wastewater separation efficiency and permeate flux of polypyrrole-decorated ceramic-polymeric membranes

Reliable modeling of oily wastewater emphasizes the paramount importance of sustainable and health-conscious wastewater management practices, which directly aligns with the Sustainable Development Goals (SDG) while also meeting the guidelines of the World Health Organization (WHO). This research explores the efficiency of utilizing polypyrrole-coated ceramic-polymeric membranes to model oily wastewater separation efficiency (SE) and permeate flux (PF) based on established experimental procedures. In this area, computational simulation still needs to be explored. The study developed predictive regression models, including robust linear regression (RLR), stepwise linear regression (SWR) and linear regression (LR) for the ceramic-polymeric porous membrane, aiming to interpret its complex performance across diverse conditions and, thus, develop its utility in oily wastewater treatment applications. Subsequently, a novel, simple average ensemble paradigm was explored to reduce errors and improve prediction skills. Prior to the development of the model, stability and reliability analysis of the data was conducted based on Philip Perron tests with the Bartlett kernel estimation method. The accuracy of the SE exhibited a high consistency, averaging 99.92% with minimal variability (standard deviation of 0.026%), potentially simplifying its prediction compared to PF. The modes were validated and evaluated using metrics like MAE, RMSE, Speed, and MSE, in addition to 2D graphical and cumulative distribution function graphs. The LR model emerged as the best with the lowest RMSE =0.21951, indicating superior prediction accuracy, followed closely by RLR with an RMSE = 0.22359. SWLR, while having the highest RMSE = 0.34573, marked its dominance in prediction speed with 110 observations per second. Notably, the RLR model justified a reduction in error by approximately 35.29% compared to SWLR. Moreover, the training efficiency of the LR model exceeded, demanding a mere 2.9252 s, marking a reduction of about 32.54% compared to SWLR. The improved simple ensemble learning proved merit over the three models regarding error accuracy. This study emphasizes the essential role of soft-computing learning in optimizing the design and performance of ceramic-polymeric membranes.

Recent Advancements in Metal-Organic Framework-Based Membranes for Hydrogen Separation: A Review

Metal-organic frameworks (MOFs) are promising porous materials that have huge potential for gas separation when put in the membrane configuration. MOFs have huge potential due to certain salient features of the MOFs such as excellent pore size, ease of tuning the pore chemistry, higher surface area, and chemical and thermal stabilities. MOFs have been explored for various gas separation and storage applications. This review discusses various approaches for fabricating MOFs-based membranes for the separation of H2 gas from a variety of feeds having various gases CO2 , CO, N2 , and CH4 as impurities. The emphasis has been put on three types of membranes for H2 separation which include MOFs-based hollow fibrous/tubular/disk membranes, MOFs-based mixed matrix membranes (MMMs), and MOFs-based stand-alone membranes. In addition, various challenges such as reducing inhomogeneity between MOFs and polymeric matrices have also been discussed. Similarly, the approaches to successfully decorating MOFs on different supports in different configurations have been explained. The possible ways of improving the MOFs-based membranes for H2 have also been discussed.

Fabrication of polyamide thin film composite membranes using aliphatic tetra-amines and terephthaloyl chloride crosslinker for organic solvent nanofiltration

Given the huge significance of organic solvents in several industrial processes, the use of membranes for recovering the solvents has evolved into an industrially viable process. The current work has been focused on studying the effect of minor changes in the chemistry of the reacting monomers on the organic solvent nanofiltration/solvent resistance nanofiltration (OSN/SRNF) performance of the membranes. The two aliphatic amines with varying aliphatic chain lengths between primary and secondary amines were selected for this purpose. Based on the structure of the resultant active layer, the Janus nanofiltration performance of the membrane was evaluated. The two membranes, 4A-TPC@crosslinked PAN and 4A-3P@crosslinked PAN were fabricated by using two different tetra-amines, 4A (N,N'-bis(3-aminopropyl)ethylenediamine) and 4A-3P (N,N'-Bis(2-aminoethyl)-1,3-propanediamine) crosslinked with terephthaloyl chloride (TPC) on a crosslinked polyacryonitrile (PAN) support through interfacial polymerization (IP). The presence of multiple hydrophobic -CH₂- groups in the structures of the aliphatic amines 4A and 4A-3P develops hydrophobic sites in the hydrophilic polyamide active layers of the membranes. In addition, 4A has two secondary amino groups separated by ethylene (-CH₂-CH₂-) groups, whereas in 4A-3P, the two secondary amino groups are separated by propylene (-CH₂-CH₂-CH₂-) leading to variation in the structural features and performance of the two membranes. Both membranes were fully characterized by several membrane characterization techniques and applied for OSN/SRNF using both polar (methanol, ethanol, and isopropanol) and non-polar (n-hexane and toluene) solvents. Different dyes (Congo red, Eriochrome black T, and Methylene blue) were used as model solutes during the filtration experiment. The 4A-3P-TPC@crosslinked PAN showed n-hexane and toluene flux of 109.9 LMH and 95.5 LMH, respectively. The Congo red (CR) showed the highest rejection, reaching 99.1% for the 4A-TPC@Crosslinked PAN membrane and 98.8% for the 4A-3P-TPC@Crosslinked PAN membrane.

Removal of pharmaceutically active compounds from water sources using nanofiltration and reverse osmosis membranes: Comparison of removal efficiencies and in-depth analysis of rejection mechanisms

Trace organic compounds from effluent streams are not completely removed by conventional purification techniques and hence, contaminating groundwater sources. Herein, we report the removal efficiency and rejection mechanisms of three common pharmaceutically active compounds (PhACs); caffeine (CFN), omeprazole (OMZ), and sulfamethoxazole (SMX), using commercial nanofiltration (NF) and reverse osmosis (RO) membranes with different surface characteristics. The RO membranes showed near-complete removal of all PhACs with rejection rates >99%. On the other hand, retention capabilities for the NF membranes varied and were influenced by the characteristics of the PhACs, membranes, and the feed solution. In general, during long-term testing, the rejection did not show much variation and followed a trend compatible with the size exclusion (steric hindrance) mechanism. When a real matrix was used, the rejection of CFN by the more tight NF membranes, HL TFC and NFW decreased by ∼10%, whereas the removal of SMX by the loose NF membrane, XN45, increased by the same ratio. In short-term testing, the rejection of negatively charged SMX increased significantly (∼20-40%) at a higher pH of ∼8 and in the presence of salts. Fouling by the PhACs was more severe on the high-flux NF membranes, HL TFC and XN45, as witnessed by the significant change in Contact angle (CA) values (∼25-50°) as well as the flux decline (∼15%) during long-term testing. To summarize, the removal of PhACs by membranes is a complex phenomenon and depends upon a combination of several factors.

Recovery of Dissolved Hydrogen Sulfide from Various Wastewater Streams Using Membranes and Other Relevant Techniques: A Review

Given the significance of dissolved H₂S, various techniques have been explored in the literature. The current review describes in detail the various membrane-based techniques, such as membrane contactors, for removing dissolved H₂S from various wastewater streams. Various types of hydrophobic membranes have been used, with more emphasis placed on PVDF hollow fiber membranes. The hydrophobic membranes do not allow water to pass through, whereas H₂S is readily allowed to pass through the membrane at ambient conditions. In addition, the use of monoethanol amine triazine (MEA-Triazine)- based H₂S scavengers has also been described in detail, including the possible scavenging mechanism. The possibility of different types of byproducts has also been explained along with the possible routes to get rid of scavenger byproducts, such as apDTZ. The use of peroxy acetic acid has also been explained to oxidize and solubilize apDTZ. Furthermore, the use of vacuum-based dissolved H₂S gas has also been described in detail. The application of the Knudsen and bulk diffusion models to the separation of dissolved H₂S through the pores of the hollow fibers has also been explained. Finally, the future challenges and possible solutions along with concluding remarks have also been mentioned in the current review.

Decoration of β-Cyclodextrin and Tuning Active Layer Chemistry Leading to Nanofiltration Membranes for Desalination and Wastewater Decontamination

Given the huge potential of thin film composite (TFC) nanofiltration (NF) membranes for desalination and micro-pollutant removal, two different sets of six NF membranes were synthesized. The molecular structure of the polyamide active layer was tuned by using two different cross-linkers, terephthaloyl chloride (TPC) and trimesoyl chloride (TMC), reacted with tetra-amine solution containing β-Cyclodextrin (BCD). To further tune the structure of the active layers, the time duration of interfacial polymerization (IP) was varied from 1 to 3 min. The membranes were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle (WCA), attenuated total reflectance Fourier transform infra-red (ATR-FTIR) spectroscopy, elemental mapping and energy dispersive (EDX) analysis. The six fabricated membranes were tested for their ability to reject divalent and monovalent ions followed by rejection of micro-pollutants (pharmaceuticals). Consequently, terephthaloyl chloride turned out to be the most effective crosslinker for the fabrication of membrane active layer with tetra-amine in the presence of β-Cyclodextrin using interfacial polymerization reaction for 1 min. The membrane fabricated using TPC crosslinker (BCD-TA-TPC@PSf) showed higher % rejection for divalent ions (Na₂SO₄ = 93%; MgSO₄ = 92%; MgCl₂ = 91%; CaCl₂ = 84%) and micro-pollutants (Caffeine = 88%; Sulfamethoxazole = 90%; Amitriptyline HCl = 92%; Loperamide HCl = 94%) compared to the membrane fabricated using TMC crosslinker (BCD-TA-TMC@PSf). For the BCD-TA-TPC@PSf membrane, the flux was increased from 8 LMH (L/m².h) to 36 LMH as the transmembrane pressure was increased from 5 bar to 25 bar.

Fabrication of Photo-Responsive Mesh Membrane with Surface-Engineered Wettability for Oil-Water Separation and Photocatalytic Degradation of Organic Pollutants

A photo-responsive TiO₂-coated stainless-steel mesh membrane (TiO₂@SSM), possessing unique surface wettability, was fabricated. This TiO₂@SSM membrane is found to be capable of separating oil and water from oily water and has the potential to carry out photocatalytic self-cleaning and/or the degradation of organic pollutants present in water. The fabrication of TiO₂@SSM is quite simple: titanium dioxide (TiO₂) nanoparticles were spray-coated onto stainless steel microporous mesh (SSM) substrates and annealed at the temperature of 500 °C. The fabricated TiO₂@SSM membrane was structurally and morphologically characterized by XRD, FE-SEM, EDX, and elemental mapping. The contact angle measurements using a goniometer showed that the fabricated TiO₂@SSM membrane surface is superhydrophilic and superoleophilic in air and superoleophobic under water. This is a favorable wetting condition for the water passing oil-water separation membrane, and this water passing property of the membrane eased the common problem of the fast clogging of the membrane by oil. An oil-water separation efficiency of about 99% was achieved, when the TiO₂@SSM membrane was used as the separating medium in the gravity-driven oil-water separation system, unlike the uncoated stainless steel mesh membrane, which allowed both oil and water to pass together. This confirmed that the oil-water separating functionality of the membrane is attributed to TiO₂ coating on the stainless steel mesh. The photocatalytic degradation property of the TiO₂@SSM membrane is an added advantage, where the membrane can be potentially used for self-cleaning of the membrane's surface and/or for water purification.

Photocatalytic deactivation of sulphate reducing bacteria using visible light active CuO/TiO2 nanocomposite photocatalysts synthesized by ultrasonic processing

Sulphate-reducing bacteria wreaks havoc to oil pipelines, as it is an active agent for scale formation in the oil production tubing, and plugging of reservoir rock around the oil wells, and this leads to the degradation of oil quality. In this work, we synthesized copper oxide/titanium dioxide nanocomposite photocatalysts with three different mass contents of copper oxide (10%, 20% and 30%) and used them as an effective photo-catalyst in the process of photo-catalytic deactivation of sulphate-reducing bacteria. The anchoring of copper oxide on titanium dioxide brought about the following positive attributes in copper oxide/titanium dioxide nanocomposite pertained to the photo-catalyst: (i) the material transformed to visible light active with the potential to harness the more efficient visible spectral region of the solar radiation, (ii) increased surface area on the photo-catalyst enhanced the number of active reaction sites in the material, and (iii) efficiently retarded the undesired photo-generated electron hole recombination to promote the photo-catalytic activity. Although, the photo-catalyst effective under both UV and visible light, the deactivation was found to be higher in visible radiation, particularly the nanocomposite with 20%- copper oxide on titanium dioxide showed the highest photocatalytic degradation with of Sulphate-reducing bacteria with a decay constant as high as 1.38 min ^-1 and the total depletion time as low as 8 min. It was confirmed that the bacterial deactivation was neither due to the bactericidal effect of the nanocomposite nor due to the light mediated deactivation.

An efficient and simple strategy for fabricating a polypyrrole decorated ceramic-polymeric porous membrane for purification of a variety of oily wastewater streams

A ceramic-polymeric membrane was fabricated through in-situ oxidative polymerization of pyrrole (Py) on alumina (Al₂O₃) ceramic ultrafiltration support. The establishment of polypyrrole (PPy) active layer on the ceramic support led to a new PPy coated ceramic-polymeric membrane. Various salient features such as surface wettability, surface morphology, composition and functional goups of PPy coated ceramic-polymeric membrane were determined by various characterization techniques water contact angle (WCA), scanning electron microscopy (SEM), energy dispersive x-ray (EDX) analysis and attenuated total reflectance fourier transform infrared (ATR-FTIR). The PPy coated ceramic-polymeric membrane showed superhydrophilic nature owing to its under water oil contact angle of ≥160° (superoleophobic). Thanks to stable deposition of PPy active layer on ceramic support, the membrane retained a separation efficiency of >99% for O/W emulsions at varied transmembrane pressures ranging from 0.5 bar to 2 bar with a feed concentration of 125 ppm of oil in water. Moreover, the PPy coated ceramic-polymeric membrane exhibited an ideal behaviour to the applied transmembrane pressure with a linear increase from 380 LMH to 2112 LMH in permeate flux as the pressure increased from 0.5 bar to 2 bar. As the concentration of oil was raised from 50 ppm to 250 ppm, the separation efficeincy separation remained at >99%. From among the different types of oils (Motor oil, Diesel oil and Crude oil) to mimic the oily waste water streams, the permeate flux was found to be highest in case of motor oil with a value reaching to 1690 LMH at 1 bar. The stability test revealed that the PPy coated ceramic-polymeric membrane was able to separate >99% of 125 ppm O/W surfactant stabilized emulsion for a period of 420 min.

Customization of surface wettability of nano-SiO2 by coating Trimethoxy(vinyl)silane modifier for oil-water separation: Fabrication of metal-based functional superwetting nanomaterial, characterizations and performance evaluation

The wettability of nano-SiO₂ surface was transformed from the inherent hydrophilicity to functional superhyderophobicity by coating Trimethoxy (vinyl)silane modifier, and the resultant surface showed contrasting wettability for water and oil (Superhydrophobic and Superoleophilic), which is a desired characteristic for the membranes used in oil-water separation. Initially Trimethoxy (vinyl)silane coated SiO₂ nanoparticles (TMVS@SiO₂) were synthesized by hydrolysis and poly-condensation reactions, and this nano dispersion was spray coated on the annealed stainless-steel mesh surface, whose resulting hierarchical surface texture brought about the desired wettability, with the water-surface-air (θ_WA) and oil-surface-air (θ_OA) interfacial contact angles of 150° and 0° respectively. In addition to the wettability studies (contact angles), FTIR, morphological, and elemental characterizations of the TMVS@SiO₂ coated surfaces were carried out to understand the alterations that have taken place on the TMVS@SiO₂ surface that in turn rendered superhydrophobicity and superoleophilicity to the surface. The FTIR absorption peaks indicate that after modifying SiO₂ with TMVS, the -OH groups on SiO₂ surface are clearly replaced by -CH₃. The morphological studies indicated that modification of SiO₂ leads to better cross-linking between coating composition and nanoparticles and EDS spectra and elemental mapping of the modified surface showed the presence of Si, O and C elements. Finally, this surface was tested for its efficiency and stability as a membrane in the process of separating oil and water from the oily water using gravity driven method. The oil-water separation efficiency was estimated to be 99% for this membrane and also it was found to be quite stable as the surface effectively retained this oil-water separation efficiency even after 10 cycles of separation process.

NH2-CuO-MCM-41 covalently cross-linked multipurpose membrane for applications in water treatment: Removal of hazardous pollutants from water, water desalination and anti-biofouling performance

The current study was planned to fabricate a new set of membranes to target multiple application areas such as desalting, removal of micropollutants and antibiofouling performance. In-situ incorporated copper oxide to MCM-41 (CuO-MCM-41) was synthesized and amine (-NH₂) functionalized by reacting with N1-(3-trimethoxy silylpropyl) diethylenetriamine (NTSDETA) yielding NH₂-CuO-MCM-41. Different concentrations of NH₂-CuO-MCM-41 were covalently cross-linked in polyamide active layer during interfacial polymerization (IP) between N, N'-bis(3-aminopropyl)ethylenediamine and terephthaloyl chloride (TPC) on polysulfone/poly ester terephthalate (PS/PET) support. The membranes were extensively characterized by Water Contact Angle (WCA), Scanning Electron Microscopy (SEM), Fourier Transform Infra-red (FTIR) spectroscopy, Energy Dispersive X-ray (EDX) analysis, Elemental mapping and Powder X-ray Diffraction (PXRD). From among the different versions of X-CuO-MCM-41/PA@PS/PET membranes, the 0.05%-CuO-MCM-41/PA@PS/PET membrane showed best performance in terms of rejecting a variety of salts, micropollutants and antibiofouling. The 0.05%-CuO-MCM-41/PA@PS/PET showed >98% rejection of MgCl₂ and 78% rejection of caffeine with a permeate flux of 16 LMH at 25 bar. The 0.1-NH₂-CuO-MCM-41inhibited S. aureus growth by 51.7%. Hence, the current strategy of membrane fabrication proved to be highly efficient for multipurpose applications in water treatment.

A Simple Approach to Fabricate Composite Ceramic Membranes Decorated with Functionalized Carbide-Derived Carbon for Oily Wastewater Treatment

Membrane-based oil−water separation has shown huge potential as a remedy to challenge oily wastewater with ease and low energy consumption compared to conventional purification techniques. A set of new composite ceramic membranes was fabricated to separate surfactant-stabilized oil/water (O/W) emulsion. Carbide-derived carbon (CDC) was functionalized by 3-aminopropyltriethoxy silane (APTES) and subsequently deposited on a ceramic alumina support and impregnated with piperazine as an additional amine. The APTES functionalized CDC-loaded membrane was then crosslinked using terephthalyol chloride (TPC). Different loadings of functionalized CDC (50 mg, 100 mg and 200 mg) were employed on the ceramic support resulting in three versions of ceramic membranes (M-50, M-100 and M-200). The fabricated membranes were thoroughly characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Attenuated total teflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Energy dispersive x-ray spectroscopy (EDX) and elemental mapping. The highest permeate flux of 76.05 LMH (L m−2 h−1) at 1 bar using 67.5 ppm oil-in-water emulsion (as feed) was achieved by the M-50 membrane, while an oil separation efficiency of >99% was achieved by using the M-200 membrane. The tested emulsions and their respective permeates were also characterized by optical microscopy to validate the O/W separation performance of the best membrane (M-100). The effect of feed concentration and pressure on permeate flux and oil−water separation efficiency was also studied. A long-term stability test revealed that the M-100 membrane retained its performance for 720 min of continuous operation with a minor decrease in permeate flux, but the O/W separation efficiency remained intact.

Semiconducting graphitic carbon nitride integrated membranes for sustainable production of clean water: A review

Semiconducting membranes integrated with nanomaterials have placed themselves in new emerging researches tremendously for seawater desalination, oil-water separation, disinfection, removal of inorganic as well as organic pollutants. Howbeit, only nanoparticles unified membranes show quite a lot lags in their performance, although some of these particles associated with the demerits of high cost. In contrast, graphitic carbon nitride incorporated membranes offered improved aforementioned properties corresponding to absolute essential qualities such as cost-effective, environmentally friendly, easy-to-operate, green manufacturing, anti-fouling, and low energy consumption. Moreover, their high mechanical strength, high stability against harsh environment and long-term utilization without flux reduction are strong plus. Even though there are some undeniable downsides of these membranes in real world applications as bulk synthesis, consistent dispersion of graphitic carbon nitride, low photocatalytic efficiency etc. Accordingly, in the present article, these frailties of the membranes having graphitic carbon nitride as a filler and their respective synthesis procedures and properties are discussed. A comprehensive analysis over the application of semiconducting graphitic carbon nitride incorporated membranes with and without special surface modification; and exploration of the future challenges and difficulties associated to these membranes are also reviewed. Consequently, the current article provides brief overview about graphitic carbon nitride integrated composite membranes as well as their applications, and it finished up with new thoughts of further improvements/modifications to overcome their shortcomings in actual environmental conditions.

Facile Modification of NF Membrane by Multi-Layer Deposition of Polyelectrolytes for Enhanced Fouling Resistance

Fouling not only deteriorates the membrane structure but also compromises the quality of the permeate and has deleterious consequences on the membrane operation. In the current study, a commercial thin film composite nanofiltration membrane (NF90) was modified by sequentially depositing oppositely charged polycation (poly(allylamine hydrochloride)) and polyanion (poly(acrylic acid)) polyelectrolytes using the layer-by-layer assembly method. The water contact angle was decreased by ~10° after the coating process, indicating increased hydrophilicity. The surface roughness of the prepared membranes decreased from 380 nm (M-0) to 306 nm (M-10) and 366 nm (M-20). M-10 membrane showed the highest permeate flux of 120 L m-2 h-1 with a salt rejection of >98% for MgSO4 and NaCl. The fabricated membranes M-20 and M-30 showed 15% improvement in fouling resistance and maintained the initial permeate flux longer than the pristine membrane.

The SIMULATE ureteroscopy training curriculum: educational value and transfer of skills

Objective

Different simulation modalities may be utilised in a curricular fashion to benefit from the strengths of each training model. The aim of this study is to evaluate a novel multi-modality ureterorenoscopy (URS) simulation curriculum in terms of educational value, content validity, transfer of skills and inter-rater reliability.

Methods

This international prospective study recruited urology residents (n = 46) with ≤ 10 URS experience and no prior simulation training. Participants were guided through each phase of the expert-developed SIMULATE URS curriculum by trainers and followed-up in the operating room (OR). Video recordings were obtained during training. A post-training evaluation survey was distributed to evaluate content validity and educational value, using descriptive statistics. Performance was evaluated using the objective structured assessment of technical skills (OSATS) scale to measure improvement in scores throughout the curriculum. Pearson’s correlation coefficient and Cohen’s kappa tests were utilised to investigate correlation and agreement between raters.

Results

Participants reported gaining OR-transferrable skills (Mean: 4.33 ± 0.67) and demonstrated marked improvement in throughout the curriculum, transferred to the OR for both semi-rigid URS (p = 0.004) and flexible URS (p = 0.007). 70% of participants were successfully followed-up in the OR (n = 32). No differences were identified with the additional use of fresh frozen cadavers (p = 0.85, p = 0.90) and the URO Mentor VR simulator (p = 0.13, p = 0.22). A moderate level of correlation was noted on the video OSATS assessments, between two expert assessors (r = 0.70), but a poor agreement with the live rating.

Conclusion

The SIMULATE URS training curriculum received high educational value from participants, who demonstrated statistically significant improvement with consecutive cases throughout the curriculum and transferability of skills to the OR in both semi-rigid and flexible URS.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-021-03604-w.

Relationship of working capital management and profitability of the firms - an application of unit root and co-integration test on the various corporate sectors of Pakistan stock exchange

The main purpose of this research is to find the impact and the long-run relationship of working capital, and profitability in different major sectors of Pakistan stock exchange; for this purpose eight sectors with 95 listed companies selected that can be representative of the Pakistani mindset and practices of the corporate world. For this reason, ROA used as the dependent variable and CCC, CR, QR, WCT ART, APD, ROCE, DR to check the long-run relationship with Firm Performance. OLS is not possible due to the trend in data. In this research unit root test and Penal Co-integration test used for finding the long-run relationship equilibrium. This research paper provides guidelines to corporate practitioners and academia to understand and focus on working capital to improve profitability in the organization. Findings revealed that different sectors have different characteristics of working capital in the long-run equilibrium. This research intends to give future direction for the researcher to develop theories of liquidity and working capital.

Simulation-Based Training Models for Urolithiasis: A Systematic Review

Objectives: Urolithiasis is one of the most common presentations in urological practice and it is becoming increasingly important to provide structured, simulation-based training using validated training models. This systematic review aims to identify current simulation-based training models and to evaluate their validity and effectiveness. Methods: Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a comprehensive search was performed on the Medline and EMBASE databases for English language articles published between 2000 and 2018 describing and/or assessing validity of simulation models for urolithiasis procedures. Studies were qualitatively assessed for validity using the Messick validity framework and models were assigned levels of recommendation using the McGaghie model of translational outcomes. Results: A total of 98 studies were included in this study assessing 51 models, with 28 studies concerning models for urethrocystoscopy, 46 studies for ureterorenoscopy, and 39 studies for percutaneous access and/or nephrolithotomy. Only four models demonstrated a level of recommendation of 4. The most validated models were the URO/PERC-Mentor (Simbionix, Lod, Israel) with multiple studies for each across various procedural skills. Conclusion: There is a wide spectrum of simulation-based models currently available for urolithiasis procedures, mostly with limited validity evidence from small studies. Further research is required with higher levels of evidence including randomized controlled trials. In addition, long-term transfer of skills to the operating room should be assessed to establish whether there is genuine skill development and retention using simulation models and whether this helps to reduce surgical complications.

A grounded theory exploration of appraisal Process of Capital Investment Decisions — Capex Appraisal Model (CAM)

The purpose of this study was to explore the appraisal process of capital investment decisions. The study adopted the grounded theory approach for the exploration of the objective. In the first stage, 48 in-depth interviews were conducted from finance executives of PSX listed companies. After transcription of all of the interviews, NVIVO software was used for analysis. Theoretical sampling was used in this study. Initially, 35 concepts and 19 categories were obtained from the initial coding of 48 cases. In the next stage, using focused coding, 19 initial categories into 09 categories were classified. These 09 categories represent each stage of the appraisal process of capital investment. These stages are Idea generation, Strategic planning, Analysis, Risk Evaluation, Selection, Mode of finance, Implementation, Monitoring and control, and Post-audit. The development of appraisal process stages is the novelty of this study and key theoretical contribution. Findings provide an in-depth understanding of the systematic way that industry appraises capital investments. This study opens grounds for new knowledge for academia, adds to relevant literature and reduces the gap between the corporate world and academia.

Evaluation of bioactivities of zinc oxide, cadmium sulfide and cadmium sulfide loaded zinc oxide nanostructured materials prepared by nanosecond pulsed laser

The present study reports the preparation of cadmium sulfide (CdS) loaded zinc oxide (ZnO) nanostructured semiconductor material and its anti-bioactivity studies against cancerous and fungus cells. For composite preparation, two different mass ratios of CdS (10 and 20%) were loaded on ZnO (10%CdS/ZnO, 20%CdS/ZnO) using a 532 nm pulsed laser ablation in water media. The structural and morphological analyses confirmed the successful loading of nanoscaled CdS on the surface of ZnO particles, ZnO particles were largely spherical with average size ~50 nm, while CdS about 12 nm in size. The elemental and electron diffraction analyses reveal that the prepared composite, CdS/ZnO contained both CdS and ZnO, thus reaffirming the production of CdS loaded ZnO. The microscopic examination and MTT assay showed the significant impact of ZnO, CdS, and CdS loaded ZnO on human colorectal carcinoma cells (HCT-116 cells). Our results show that the prepared ZnO had better anticancer activities than individual CdS, and CdS loaded ZnO against cancerous cells. For antifungal efficacy, as-prepared nanomaterials were investigated against Candida albicans by examining minimum inhibitory/fungicidal concentration (MIC/MFC) and morphogenesis. The lowest MIC (0.5 mg/mL), and MFC values (1 mg/mL) were found for 10 and 20%CdS/ZnO. Furthermore, the morphological analyses reveal the severe damage of the cell membrane upon exposure of Candida strains to nanomaterials. The present study suggests that ZnO, CdS, and CdS loaded ZnO nanostructured materials possess potential anti-cancer and anti-fungal activities.

Laser Induced Anchoring of Nickel Oxide Nanoparticles on Polymeric Graphitic Carbon Nitride Sheets Using Pulsed Laser Ablation for Efficient Water Splitting under Visible Light

A visible-light-active nickel oxide-graphitic carbon nitride (NiO@g-CN) hetero-structured nanocomposite was synthesized for the first time by pulsed laser ablation in liquid and used as a photoanode material in photoelectrochemical water-splitting reaction with a solar simulator. It was found that the photoelectrochemical performance of PLAL synthesized NiO@g-CN nanocomposite as photoanode, compared to g-CN as photoanode showed fourfold enhancements in photocurrent density under visible light. FT-IR, XRD, FE-SEM, and EDX consistently showed the proper anchoring of nano-sized NiO on g-CN. UV-DRS and the band gap estimation showed the narrowing down of the band gap energy and consequent enhancement in the visible-light absorption, whereas photoluminescence spectroscopy confirmed the reduction of the recombination of photo-excited electron hole pairs as a result of the anchoring of NiO on g-CN. The photoelectrochemical performance of g-CN and the NiO@g-CN nanocomposite photoanodes was compared by linear sweep voltammetry (LSV), Chronoamperometry (I-t), and Electrochemical Impedance Spectroscopy (EIS). All of these results of the characterization studies account for the observed fourfold enhancement of photocurrent density of NiO@g-CN nanocomposite as photoanode in the photoelectrochemical reaction.

Investigation of the survival viability of cervical cancer cells (HeLa) under visible light induced photo-catalysis with facile synthesized WO3/ZnO nanocomposite

The photo catalytic degradation, a proven chemical process used for the decontamination of organic/inorganic pollutants and microorganisms in water was implemented. In this work for the selective killing of cervical cancer cells (HeLa cells) by using nano-composite of ZnO (Zinc Oxcide), WO₃ (tungsten oxide) and (n-WO₃/ZnO) as a photo-catalyst under the irradiation of visible light. All the three nanostructured semiconducting materials (WO3, ZnO and n-WO3/ZnO) were synthesized by facile chemical precipitation method and their morphological and optical characterization studies were carried out to elucidate the observed enhancement in the photo-catalytic killing of HeLa cancer cells with n-WO3/ZnO as a photo-catalyst. After 60 min of photo-catalytic reaction with n-WO₃/ZnO as a photo-catalyst, a survival viability of HeLa cancer cells as low as 15% was achieved (nearly 85% of killing), as compared to 65% of HeLa cancer cell survival viability (nearly 35% of killing) with individual use of WO₃ and ZnO as photo-catalysts under the same irradiation and experimental conditions. This improved photo-catalytic killing of HeLa cancer cells using n-WO₃/ZnO in the visible spectral region is attributed to the enhanced visible light absorption and reduced electron hole recombination, characteristically brought about in the n-WO₃/ZnO composite material. As photo-catalytic killing of the cancer cells can be selective, localized and reasonably efficient, in principle, this method can be considered as a non-invasive targeted treatment option for killing any type of cancer cells. HeLa cells, in particular are the cervical cancer cell and the tumors in and around cervix, containing HeLa cells can be non-surgically accessed and photo-catalytically treated with appropriate photo-catalyst and light source.

Single step production of high-purity copper oxide-titanium dioxide nanocomposites and their effective antibacterial and anti-biofilm activity against drug-resistant bacteria

In the present research work, copper oxide-titanium dioxide nanocomposites were synthesized for the first time using advanced pulsed laser ablation in liquid (PLAL) technique for disinfection of drug-resistant pathogenic waterborne biofilm-producing bacterial strains. For this, a series of copper oxide-titanium dioxide nanocomposites were synthesized by varying the composition of copper oxide (5%, 10%, and 20%) with titanium dioxide. The pure titanium dioxide and copper oxide-titanium dioxide nanocomposites were characterized by advanced instrumental techniques. XRD, TEM, FE-SEM, EDX, elemental mapping and XPS analysis results consistently revealed the successful formation of copper oxide-titanium dioxide nanocomposites using PLAL technique. The antibacterial and antibiofilm activities of pure titanium dioxide and copper oxide-titanium dioxide nanocomposites were investigated against biofilm-producing strains of Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa by various methods. Our results revealed that the PLAL synthesized copper oxide-titanium dioxide nanocomposites showed enhanced anti-biofilm and antibacterial activity compared to pure titanium dioxide in a dose-dependent manner against targeted pathogens. Furthermore, the effects of pure titanium dioxide and copper oxide-titanium dioxide nanocomposites on bacterial morphology, biofilm formation, aggregation and their colonization by targeted pathogens were also examined using scanning electron microscopy. Microscopic images clearly showed that the cell envelope of almost all the cells were rumples, rough, had irregularities and abnormal appearance with the major damage being characterized by the formation of "pits". Many depressions and indentations were also seen in their cell envelope and the original shape of Pseudomonas aeruginosa cells changed from normal rod to swollen, large and elongated which indicates the loss of membrane integrity and damage of cell wall and membrane. The findings suggested that PLAL synthesized copper oxide-titanium dioxide nanocomposites have good potential for removal of biofilm or killing of pathogenic bacteria in water distribution network and for wastewater treatment, hospital and environmental applications. In addition, cytotoxic activity of pure TiO₂ and PLAL synthesized copper oxide-titanium dioxide nanocomposites against normal and healthy cells (HEK-293) and cancerous cells (HCT-116) were also evaluated by MTT assay. The MTT assay results showed no cytotoxic effects on HEK-293 cells, which suggest TiO₂ and PLAL synthesized copper oxide-titanium dioxide nanocomposites are non-toxic to the normal cells.

Synthesis, characterization and evaluation of visible light active cadmium sulfide-graphitic carbon nitride nanocomposite: A prospective solar light harvesting photo-catalyst for the deactivation of waterborne pathogen

Cadmium sulfide-graphitic carbon nitride nanocomposite was synthesized by pulsed laser ablation in liquid, and it was found from the results of optical and morphological characterizations that the proper anchoring of nanostructured cadmium sulfide on the nano-sheets of graphitic carbon nitride took place, which brought about the positive attributes such as enhanced visible light absorption and reduced photo-generated charge recombination, the key features required for an efficient photo-catalyst by solar light harvesting. The pulsed laser ablation in liquid method adopted for the synthesis of cadmium sulfide-graphitic carbon nitride has the following advantages: the shape and size of the synthesized particles can be controlled by altering the experimental parameters such as laser wavelength, pulse laser duration, the pH of the solution, the surfactants and the temperature of the solution, pulsed laser ablation in liquid method neither requires cumbersome equipment nor does it require intermediate chemicals and catalysts nor does it necessitate the post synthesis purification. The enhancement of photo-catalytic activity of cadmium sulfide-graphitic carbon nitride nanocomposite was tested for the photo-catalytic deactivation of Escherichia coli bacteria in water under visible light radiation. As anticipated, a significant improvement of photo-catalytic deactivation was observed, which is attributed to the enhanced and extended light absorption in the visible spectral region, and the formation of herterojunction between the semiconductors, which is instrumental in inhibiting the undesired recombination of photo-generated charge carriers. Quantitatively, the presence of cadmium sulfide on the graphitic carbon nitride surface contributed to a remarkable 129% increase of photo-catalytic degradation constant compared to pure graphitic carbon nitride, which resulted in the decrease of total depletion time of Escherichia coli from 156 min to 67 min with the cadmium sulfide-graphitic carbon nitride nanocomposite synthesized by pulsed laser ablation in liquid method. Our results on the efficient photo-catalytic deactivation of Escherichia coli under visible light assures that cadmium sulfide-graphitic carbon nitride nanocomposite can very well be used for photo-catalytic water purification by harvesting the abundant solar light.

Effects of Oxidizing Media on the Composition, Morphology and Optical Properties of Colloidal Zirconium Oxide Nanoparticles Synthesized via Pulsed Laser Ablation in Liquid Technique

In this work, pulsed laser ablation in liquid (PLAL) technique was applied to synthesize colloidal nanoparticles of zirconium oxide (ZrO2) in three different aqueous media (de-ionized water, ethanol and acetone). The structure, morphology, composition and optical properties of the synthesized nanoparticles were characterized by XRD, SEM, TEM, XPS, UV-Vis spectrophotometer and FT-IR analysis respectively. The structural analysis by XRD reveals the formation of mixture of monoclinic and tetragonal phases of nanocrystalline zirconia. The average crystallite sizes of ZrO2 by using Scherrer's formula were estimated to be 41.8, 42.6 and 40.3 nm in water, ethanol and acetone respectively for monoclinic phase while 20.1, 24.8 and 18.9 nm were for tetragonal phase of ZrO2 in water, ethanol and acetone respectively. Microstructure of our starting materials was confirmed from SEM analysis and morphology of the synthesized nanostructured ZrO2 was studied by TEM. TEM images show that the average particle size is less than 10 nm with spherical shapes. The XPS analysis reveals the elemental compositions of ZrO2 nanoparticles and their stoichiometric ratios. Optical properties of the synthesized ZrO2 nanoparticles were studied by UV-Vis absorption spectroscopy and Fourier transform infrared spectroscopy (FT-IR). Uv-Vis absorption spectroscopy revealed that the nanoparticle produced in water has higher absorption due to higher NPs concentrations suspended in water. The band gap of the synthesized ZrO2 nanoparticles in water, ethanol and acetone were estimated from Tauc's plot to be 5.19, 5.22 and 4.94 eV respectively. FT-IR analysis also ascertained the functional groups of ZrO2 nanoparticles in the three liquid media.

Enhanced photo-catalytic activity of ordered mesoporous indium oxide nanocrystals in the conversion of CO2 into methanol

Ordered mesoporous indium oxide nanocrystal (m-In₂O₃) was synthesized by nanocasting technique, in which highly ordered mesoporous silca (SBA-15) was used as structural matrix. X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halanda (BJH) studies were carried out on m-In₂O₃ and the results revealed that this material has a highly ordered mesoporous surface with reduced grain size, increased surface area and surface volume compared to the non porous indium oxide. The diffuse reluctance spectrum exhibited substantially improved light absorption efficiency in m-In₂O₃ compared to normal indium oxide, however, no considerable change in the band gap energies of these materials was observed. When m-In₂O₃ was used as a photo-catalyst in the photo-catalytic process of converting carbon dioxide (CO₂) into methanol under the pulsed laser radiation of 266-nm wavelengths, an enhanced photo-catalytic activity with the quantum efficiency of 4.5% and conversion efficiency of 46.3% were observed. It was found that the methanol production yield in this chemical process is as high as 485 µlg^-1 h^-1 after 150 min of irradiation, which is substantially higher than the yields reported in the literature. It is quite clear from the results that the introduction of mesoporosity in indium oxide, and the consequent enhancement of positive attributes required for a photo-catalyst, transformed photo-catalytically weak indium oxide into an effective photo-catalyst for the conversion of CO₂ into methanol.

Facile synthesis of light harvesting semiconductor bismuth oxychloride nano photo-catalysts for efficient removal of hazardous organic pollutants

In the present work, bismuth oxychloride nanoparticles–a light harvesting semiconductor photocatalyst–were synthesized by a facile hydrolysis route, with sodium bismuthate and hydroxylammonium chloride as the precursor materials. The as-synthesized semiconductor photocatalysts were characterized using X-ray diffraction analysis, Fourier transform infra-red spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy, X-ray photoelectron spectroscopy and Photoluminescence spectroscopy techniques. The crystal structure, morphology, composition, and optical properties of these facile synthesized bismuth oxychloride nanoparticles (BiOCl NPs) were compared to those of traditional bismuth oxychloride. In addition, the photocatalytic performance of facile-synthesized BiOCl NPs and traditional BiOCl, as applied to the removal of hazardous organic dyes under visible light illumination, is thoroughly investigated. Our results reveal that facile-synthesized BiOCl NPs display strong UV-Vis light adsorption, improved charge carrier mobility and an inhibited rate of charge carrier recombination, when compared to traditional BiOCl. These enhancements result in an improved photocatalytic degradation rate of hazardous organic dyes under UV-Vis irradiance. For instance, the facile-synthesized BiOCl NPs attained 100% degradation of methylene blue and methyl orange dyes in approximately 30 mins under UV-Vis irradiation, against 55% degradation for traditional BiOCl under similar experimental conditions.

Sol-gel synthesis of thorn-like ZnO nanoparticles endorsing mechanical stirring effect and their antimicrobial activities: Potential role as nano-antibiotics

The effect of mechanical stirring on sol-gel synthesis of thorn-like ZnO nanoparticles (ZnO-NPs) and antimicrobial activities is successfully reported in this study. The in-house synthesized nanoparticles were characterized by XRD, SEM, TEM, FTIR, TGA, DSC and UV-visible spectroscopy. The X-Ray Diffraction analysis revealed the wurtzite crystal lattice for ZnO-NPs with no impurities present. The diametric measurements of the synthesized thorn-like ZnO-NPs (morphology assessed by SEM) were well accounted to be less than 50 nm with the help of TEM. Relative decrease in aspect ratio was observed on increasing the agitation speed. The UV-visible spectroscopy showed the absorption peaks of the ZnO-NPs existed in both UVA and UVB region. A hypsochromic shift in λmax was observed when stirring pace was increased from 500 rpm to 2000 rpm. The FTIR spectroscopy showed the absorption bands of the stretching modes of Zn-O between 500 cm⁻¹ to 525 cm⁻¹. The Thermal analysis studies revealed better stability for ZnO-NPs prepared at 2000 rpm (ZnO-2000 rpm). TGA revealed the weight loss between two main temperatures ranges viz. around (90 °C–120 °C) and (240 °C–280 °C). Finally, the effect of ZnO-NPs prepared at different stirring conditions on the growth of Gram-positive (Bacillus subtilis), Gram-negative (Escherichia coli) bacteria and a fungi (Candida albicans) were examined; which showed good antibacterial as well as antifungal properties. These findings introduce a simple, inexpensive process to synthesize ZnO-NPs using conventional methods without the use of sophisticated equipments and its application as a potent nano-antibiotic.

Qualitative and quantitative spectro-chemical analysis of dates using UV-pulsed laser induced breakdown spectroscopy and inductively coupled plasma mass spectrometry

Laser Induced Breakdown Spectroscopy (LIBS) is demonstrated for the spectral analysis of nutritional and toxic elements present in several varieties of date fruit samples available in the Saudi Arabia market. The method analyzes the optical emission of a test sample when subjected to pulsed laser ablation. In this demonstration, our primary focus is on calcium (Ca) and magnesium (Mg), as nutritional elements, and on chromium (Cr), as a toxic element. The local thermodynamic equilibrium (LTE) condition was confirmed prior to the elemental characterization of date samples to ensure accuracy of the LIBS analysis. This was achieved by measuring parameters associated with the plasma, such as the electron temperature and the electron number density. These plasma parameters aid interpretation of processes such as ionization, dissociation, and excitation occurring in the plasma plume formed by ablating the date palm sample. The minimum detection limit was established from calibration curves that involved plotting the LIBS signal intensity as a function of standard date samples with known concentrations. The concentration of Ca and Mg detected in different varieties of date samples was between 187 and 515 and 35-196mgL(-1) respectively, while Cr concentration measured between 1.72 and 7.76mgL(-1). In order to optimize our LIBS system, we have studied how the LIBS signal intensity depends on the incident laser energy and the delay time. In order to validate our LIBS analysis results, standard techniques such as inductively coupled plasma mass spectrometry (ICP-MS) were also applied on an identical (duplicate) date samples as those used for the LIBS analysis. The LIBS results exhibit remarkable agreement with those obtained from the ICP-MS analysis. In addition, the finger print wavelengths of other elements present in date samples were also identified and are reported here, which has not been previously reported, to the best of our knowledge.

Recent advances in iron complexes as potential anticancer agents

The iron complexes discussed in this review highlight their promising future as anticancer agents.

Ferroquine and its derivatives: new generation of antimalarial agents

Malaria has been teasing human populations from a long time. Presently, several classes of antimalarial drugs are available in market, but the issues of toxicity, lower efficacy and the resistance by malarial parasites have decreased their overall therapeutic indices. Thus, the search for new promising antimalarials continues, however, the battle against malaria is far from over. Ferroquine is a derivative of chloroquine with antimalarial properties. It is the most successful of the chloroquine derivatives. Not only ferroquine, but also its derivatives have shown promising potential as antimalarials of clinical interest. Presently, much research is dedicated to the development of ferroquine derivatives as safe alternatives to antimalarial chemotherapy. The present article describes the structural, chemical and biological features of ferroquine. Several classes of ferroquine derivatives including hydroxyferroquines, trioxaferroquines, chloroquine-bridged ferrocenophanes, thiosemicarbazone derivatives, ferrocene dual conjugates, 4-N-substituted derivatives, and others have been discussed. Besides, the mechanism of action of ferroquine has been discussed. A careful observation has been made into pharmacologically significant ferroquine derivatives with better or equal therapeutic effects to that of chloroquine and ferroquine. A brief discussion of the toxicities of ferroquine derivatives has been made. Finally, efforts have been made to discuss the current challenges and future perspectives of ferroquine-based antimalarial drug development.

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Structural, chemical and biological features of ferroquine have been discussed.

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Several classes of ferroquine derivatives have been reviewed.

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Mechanism of action of ferroquine has been described.

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Challenges in ferroquine-based antimalarial drug development have been highlighted.

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Perspectives in ferroquine-based antimalarial drug development have been outlined.

Photo-catalytic deactivation of sulfate reducing bacteria – a comparative study with different catalysts and the preeminence of Pd-loaded WO3nanoparticles

Photo-catalytic deactivation of SRB with pure and palladium loaded photo-catalysts was carried out and their relative efficiencies are compared.

Enzyme immobilization and molecular modeling studies on an organic–inorganic polypyrrole–titanium(iv)phosphate nanocomposite

A polypyrrole–titanium(iv)phosphate nanocomposite was synthesized by using facile chemical oxidative polymerization of pyrrole in the presence of titanium(iv)phosphate for YADH immobilization.

Facile synthesis of an electrically conductive polycarbazole–zirconium(iv)phosphate cation exchange nanocomposite and its room temperature ammonia sensing performance

An electrically conductive polycarbazole–zirconium(iv)phosphate nanocomposite based sensor was fabricated for sensing aqueous ammonia at room temperature.