Synergetic effects of boron nitride with waste zirconia: Evaluation of instantaneous fingerprint detection and mechanical properties for biomedical applications

Herein, present study mainly focuses on the synthesis and characterizations of boron nitride reinforced waste zirconia (wZrO2) with different concentrations. Composites were prepared via a scalable solid-state reaction method. Various physical parameters such as density, ionic concentration, polaron radius, and field strength were evaluated. XRD results reveal crystalline nature with a major phase of tetragonal zirconia and as boron nitride is reinforced, the tetragonal transforms into a monoclinic zirconia. Interconnected spherical grains and nanosheets were observed using FESEM. Mechanical characterizations revealed the highest compressive strength of 266 MPa. The latent fingerprints were visualized using a composite on different surfaces, implementing the powder dusting and solution techniques. MTT assay was performed and revealed good biocompatible nature. These results reveal that composite is suitable for fabrication of bioceramics with acceptable mechanical and biological performances. The composite can also be utilized for latent fingerprint detection in forensic science.

Unilateral acquired blepharoptosis due to orbital metastatic disease as an initial presentation of an overlooked breast carcinoma - A case report

INTRODUCTION AND IMPORTANCE

Orbital metastasis from breast cancer may be infrequently noted after the management of the primary lesion. It is rare in such cases to present with unilateral mechanical blepharoptosis without ophthalmoplegia.

CASE PRESENTATION

We present a case of unilateral acquired blepharoptosis of the left upper eyelid without ophthalmoplegia or exophthalmos three years after the onset of a suspicious breast mass. The patient did not disclose a history of breast cancer nor any positive family history to the ophthalmologist and anesthesiologist. The radiology images revealed an ill-defined enhanced lesion at the superior medial aspect of the left orbit. The orbital biopsy of the lesion showed poorly differentiated carcinoma as per the initial histopathology report. Vigilant history-taking enabled us to get information about a previous breast lesion and to correlate this with specific histopathological findings.

DISCUSSION

Management of orbital lesions might be challenging, and the approach should include detailed history and assessment. Biopsy and radio imaging are further needed to aid in providing the proper diagnosis. The clinicopathological correlation in our case has led to the final diagnosis of orbital metastatic breast cancer.

CONCLUSION

Ophthalmologists should be aware of variable ocular presentations of malignancy and adopt a team approach to obtain a carefully detailed history from patients presenting with orbital diseases and communicate adequately with the ocular pathologists who are handling the biopsy. Long-term follow-up and enhancement of patients' awareness of possible late orbital metastasis are recommended in all patients with breast masses.

Mechanical properties of an elastically deformable cervical spine implant

Anterior cervical surgery is widely accepted and time-tested surgical procedure for treating cervical radiculopathy and myelopathy. However, there is concern about the high adjacent segment degeneration rate and implant subsidence after the surgery using the traditional polyetheretherketone cage. Thus, we creatively designed a polyurethane cervical implant that can continuous load-sharing through elastic deformation and decrease postoperative stress concentration at adjacent segments. In this study, the design rationality and safety of this novel implant was evaluated based on several mechanical parameters including compression test, creeping test, push-out test and subsidence test. The results showed that the novel cervical implant remained intact under the compressive axial load of 8000 N and continues to maintained the elastic deformation phase. The minimum push-out load of the implant was 181.17 N, which was significantly higher than the maximum compressive shear load of 20 N experienced by a normal human cervical intervertebral disc. Besides, the creep recovery behaviour of the implant closely resembled what has been reported for natural intervertebral discs and clinically applied cervical devices in literature. Under the load of simulating daily activities of the cervical spine, the implant longitudinal displacement was only 0.54 mm. In conclusion, this study showed that the current design of the elastically deformable implant was reasonable and stable to fulfil the mechanical requirements of a cervical prosthesis under physiological loads. After a more comprehensive understanding of bone formation and stress distribution after implantation, this cervical implant is promising to be applied to certain patients in clinical practice.

Shear's role in non-union. Measuring mean angle of long bone multi-fragmentary non-unions

INTRODUCTION

Both mechanical and biological theories have been proposed in the development of non-union. The mechanical theory suggests that a high strain environment in a fracture will predispose it to non-union. While in simple fractures and wedge fractures there are only one and two primary fracture planes respectively, in multi-fragmentary fractures there are many and a non-union may form along any of the original fracture lines, however the plane which experiences the highest strain is at 45O - the shear plane. We hypothesise that in multi-fragmentary fractures the initial fracture line that most often fails to unite will tend towards the plane with the highest strain.

OBJECTIVES

1) Define the mean non-union angle in a cohort of multi-fragmentary tibial and femoral fractures. 2) In wedge-like fractures within the cohort, define and compare the mean angle of initial fracture planes which go on to form a non-union to those that unite 3) In comminuted fractures within the cohort, define the mean non-union angle DESIGN: Retrospective cohort study SETTING: Level-1 trauma centre METHODOLOGY: Fractures were categorised into wedge-like and comminuted. A published technique was utilised to measure fracture and non-union angles. In wedge-like fractures, united and non-united initial planes were compared. In comminuted fractures only the mean non-union angle was defined. Demographic patient data was also collected.

RESULTS

183 non-unions were screened, 68 patients were included. The mean non-union angle was 56°(SD 18) across all fractures. In wedge-like fractures the mean non-union angle was 59°(SD 18). In comminuted fractures the mean non-union angle was 50°(SD 19). Non-united initial fracture planes in wedge-like fractures showed a peaked distribution about a mean of 58° while united fracture planes were distributed at the extremities of the range.

CONCLUSIONS

In patients with multi-fragmentary fractures resulting in non-union, the mean tibial non-union angle was 52° while the mean femoral non-union angle was 65°. In wedge-like fractures, non-unions occurred more commonly than appropriate union in fractures between 41°-80°. The non-union angle is closer to 45° in comminuted fractures than in wedge-like fractures. These results support the mechanical theory that strain from the shear plane is an important factor in the formation of non-unions.

LEVEL OF EVIDENCE

Prognostic level 3.

Reducing oil droplet sizes from a subsea oil and gas release by water jetting a laboratory study performed at different scales

The main objective of subsea mechanical dispersion (SSMD) is to reduce the oil droplet sizes from a subsea oil release, thereby influencing the fate and behaviour of the released oil in the marine environment. Subsea water jetting was identified as a promising method for SSMD and imply that a water jet is used to reduce the particle size of the oil droplets initially formed from the subsea release. This paper presents the main findings from a study including small-scale testing in a pressurised tank, via laboratory basin testing, to large-scale outdoor basin testing. The effectiveness of SSMD increases with the scale of the experiments. From a five-fold reduction in droplet sizes for small-scale experiments to more than ten-fold for large-scale experiments. The technology is ready for full-scale prototyping and field testing. Large-scale experiments performed at Ohmsett indicate that SSMD could be comparable to subsea dispersant injection (SSDI) in reducing oil droplet sizes.

An ab-initio study of P-type ZrCoY (Y[bond, double bond]Sb and Bi) half - Heusler semiconductors

In this study, the structural, electronic, mechanical, optical, and thermoelectric properties of the cubic half-Heusler compound ZrCoY(Y[bond, double bond]Sb and Bi) obtained using first-principles calculations are presented. The following exchange-correlation functionals have been employed: Generalized Gradient Approximation with Perdew-Burke-Ernzerhoff (GGA-PBE), Generalized Gradient Approximation with Perdew-Burke-Enzerhoff for solids (GGA-PBESol) and Local Density Approximation (LDA). Both ZrCoSb and ZrCoBi compounds are mechanically and dynamically stable, based on the elastic and phonon properties analysis. The calculated electronic band gaps for both compounds are about 1 eV, as predicted by all the three functionals. Since it is noted that GGA-PBE functional is most favourable for predicting structural properties and the energetic stability of ZrCoSb and ZrCoBi compounds, it is further used to calculate their thermoelectric properties. Within the energy range of 0-40 eV, the refractive index, dielectric constant, and energy loss function of ZrCoSb and ZrCoBi compounds are calculated. The possibility of electronic transition from the valence band maximum (VBM) to the conduction minimum band (CBM) is confirmed by the occurrence of absorption peaks in the visible range. For the evaluation of thermoelectric properties, the p-type and n-type doping attained Seebeck coefficients of 1800 and -1800 μVK-1 at 300 K, respectively. The maximum peak of 17 × 1011 W/m s K2 is attained in n-type doping, according to the power factor results.

Influence of phase-separated structural morphologies on the piezo and triboelectric properties of polymer composites

Simplified and flexible fabrication methods, high output performance, and extreme flexibility of polymer-based nanocomposites represent versatile designs in self-powering devices for wearable electronics, sensors, and smart societies. Examples include polyvinylidene fluoride and its copolymers-based piezoelectric nanogenerators, green and recyclable triboelectric nanogenerators, etc. Advanced functionalities, multi-functional properties, and the extensive lifetime required for nanogenerators inspire researchers to focus on structural modifications of the polymeric materials, to fully exploit their performances. Phase separation is a physicochemical process in which polymeric phases rearrange, resulting in specific structures and properties, that ultimately influence mechanical, electronic, and other functional properties. This article will study the phase separation strategies used to modify the polymeric base, both physically and chemically, to generate the maximum electric power upon mechanical and frictional deformation. The effect of interfacial modification on the efficiency of the nanogenerators, chemical and mechanical stability, structural integrity, durable performance, and morphological appearance will be extensively covered in this review. Moreover, piezo- and triboelectric power generation have numerous challenges, such as poor resistance to mechanical deformation, reduced cyclic performance stability, and a high cost of production. These often depend on the method of developing the nanogenerators, and phase separation provides a unique advantage in reducing them. The current review provides a one-stop solution to understand and disseminate the phase separation process, types and mechanisms, advantages, and role in improving the piezoelectric and triboelectric performances of the nanogenerators.

Revision surgery following long lumbopelvic constructs for adult spinal deformity: prospective experience from two dedicated databases

PURPOSE

Pan Lumbar Arthodesis (PLA) are often required for Adult Spinal Deformity (ASD) correction, reducing significantly the compensatory capacity in case of postoperative sagittal malalignment. Few papers have investigated outcomes and complications in this vulnerable subset of patients. The objective of this study was to assess revision surgery rate for PLA in ASD, its risk factors and impact on clinical outcomes.

METHODS

Retrospective multicenter review of prospective ASD data from 7 hospitals covering Europe and Asia. ASD patients included in two prospective databases having a posterior instrumentation spanning the whole lumbar region with more than 2-years of follow-up were reviewed. Demographic, surgical, radiographic parameters and Health-Related Quality of Life (HRQoL) scores were analyzed. Univariate and multivariate regression models analyzed risk factors for revision surgery as well as surgical outcomes. Patients with Early versus Late and PJK versus Non-PJK mechanical complications were also compared.

RESULTS

Out of 1359 ASD patients included in the database 589 (43%) had a PLA and 357 reached 2-years mark. They were analyzed and compared to non-PLA patients. Average age was 67 and 82% were females. 100 Patients (28.1%) needed 114 revision surgeries (75.4% for mechanical failures). Revised patients were more likely to have a nerve system disorder, higher BMI and worst immediate postoperative alignment (as measured by GAP Parameters). These risk factors were also associated with earlier mechanical complications and PJK. Deformity and HRQoL parameters were comparable at baseline. Non-revised patients had significantly better clinical outcomes at 2-years (SRS 22 scores, ODI, Back pain). Multivariate analysis could identify nerve system disorder (OR 4.8; CI 1.8-12.6; p = 0.001), postoperative sagittal alignment (GAP Score) and high BMI (OR 1.07; CI 1.01-1.13; p = 0.004) as independent risk factors for revisions.

CONCLUSIONS

Revision surgery due to mechanical failures is relatively common after PLA leading to worse clinical outcomes. Prevention strategies should focus on individualized restoration of sagittal alignment and better weight control to decrease stress on these rigid constructs in non-compliant spines. Nerve system disorders independently increase revision risk in PLA.

LEVEL OF EVIDENCE II

Prognosis.

Mechanical complications of hip spacers: a systematic review of the literature

INTRODUCTION

Temporary spacers used in the staged revision of a hip prosthetic joint infection (PJI) have been associated with several mechanical complications with very variable reported general complications rates up to 73%. The aim of this systematic review was to assess the mechanical complications associated with hip antibiotic-loaded spacers when treating periprosthetic hip PJI.

METHODS

Through an electronic systematic search of PubMed, articles reporting mechanical complications of spacers used in the treatment of hip PJI were reviewed. Dislocations, spacer fracture, femoral fractures, and acetabular lysis rates were evaluated.

RESULTS

Forty studies were included. Standardized molded spacers had a significantly higher weighted mean of total mechanical complication rates (37.2%) when compared to standardized preformed spacers (13.8%, p = 0.039), while no significant difference was found between molded spacers and manually shaped spacers. Spacer dislocation was the most frequent complication. No significant difference in mechanical complication rate was found between spacers with and without any metallic component.

CONCLUSIONS

Spacer placement in chronic PJI of the hip with bone and soft-tissue defects is challenging and bears a high risk of mechanical failures and progressive bone loss during the interim period. A careful patient selection for spacer implantation is mandatory.

Exploration of muscle-tendon biomechanics one year after Achilles tendon rupture and the compensatory role of flexor hallucis longus

Achilles tendon (AT) rupture leads to long-term structural and functional impairments. Currently, the predictors of good recovery after rupture are poorly known. Thus, we aimed to explore the interconnections between structural, mechanical, and neuromuscular parameters and their associations with factors that could explain good recovery in patients with non-surgically treated AT rupture. A total of 35 patients with unilateral rupture (6 females) participated in this study. Muscle-tendon structural, mechanical, and neuromuscular parameters were measured 1-year after rupture. Interconnections between the inter-limb differences (Δ) were explored using partial correlations, followed by multivariable linear regression to find associations between the measured factors and the following markers that indicate good recovery: 1) tendon length, 2) tendon non-uniform displacement, and 3) flexor hallucis longus (FHL) normalized EMG amplitude difference between limbs. Δmedial gastrocnemius (MG) (β = -0.12, p = 0.007) and Δlateral gastrocnemius (β = -0.086, p = 0.030) subtendon lengths were associated with MG tendon Δstiffness. MG (β = 11.56, p = 0.003) and soleus (β = 2.18, p = 0.040) Δsubtendon lengths explained 48 % of variance in FHL EMG amplitude. Regression models for tendon length and non-uniform displacement were not significant. Smaller inter-limb differences in Achilles subtendon lengths were associated with smaller differences in the AT stiffness between limbs, and a smaller contribution of FHL muscle to the plantarflexion torque. In the injured limb, the increased contribution of FHL appears to partially counteract a smaller contribution from MG due to the elongated tendon, however the role of FHL should not be emphasized during rehabilitation to allow recovery of the TS muscles.

Boron nitride decorated poly(vinyl alcohol)/poly(acrylic acid) composite nanofibers: A promising material for biomedical applications

In this study, polyvinyl alcohol (PVA) and polyacrylic acid (PAA) nanofibers loaded with boron nitride nanoparticles (mBN) were fabricated by using electrospinning and crosslinked by heat treatment. The physical, chemical, and mechanical properties, hydrophilic behavior, and degradability of composite nanofibers were evaluated. The mechanical properties such as elastic modulus, elongation percentage at the break, and mechanical strength of PVA/PAA nanofibers improved with mBN loading. The thermal conductivity of composite nanofibers reached 0.12 W/m·K at mBN content of 1.0 wt% due to the continuous heat conduction pathways of mBN. In the meantime, while there was no cytotoxicity recorded for both L929 and HUVEC cell lines for all composite nanofibers, the antimicrobial efficiency improved with the incorporation of mBN compared with PVA/PAA and recorded as 68.8% and 75.1% for Escherichia coli and Staphylococcus aureus, respectively. On this basis, the present work proposes a promising biomaterial for biomedical applications such as dual drug delivery, particularly including both hydrophobic and hydrophilic drugs or wound dressing.

Challenges and perspectives of multi-virus biosensing techniques: A review

In the context of globalization, individuals have an increased chance of being infected by multiple viruses simultaneously, thereby highlighting the importance of developing multiplexed devices. In addition to sufficient sensitivity and rapid response, multi-virus sensing techniques are expected to offer additional advantages including high throughput, one-time sampling for parallel analysis, and full automation with data visualization. In this paper, we review the optical, electrochemical, and mechanical platforms that enable multi-virus biosensing. The working mechanisms of each platform, including the detection principle, transducer configuration, bio-interface design, and detected signals, are reviewed. The advantages and limitations, as well as the challenges in implementing various detection strategies in real-life scenarios, were evaluated. Future perspectives on multiplexed biosensing techniques are critically discussed. Earlier access to multi-virus biosensors will efficiently serve for immediate pandemic control, such as in emerging SARS-CoV-2 and monkeypox cases.

Current Challenges in Chronic Ankle Instability: Review and Perspective

Chronic ankle instability (CAI) is common, disabling, and represents a significant socioeconomic burden. Current treatment options are not adequately efficacious. CAI is multifaceted, yet it is commonly addressed in terms of either mechanical instability or functional impairment. Both are inherently linked. Basic research must be conducted to foster reliable translational research encompassing both mechanical and functional aspects. A review was conducted to identify CAI risk factors for inclusion in future studies, and we offer here opinions and perspectives for future research.

Dexamethasone-doped nanoparticles improve mineralization, crystallinity and collagen structure of human dentin

OBJECTIVES

Bioactive materials have been used for functionalization of adhesives to promote dentin remineralization. This study aims to evaluate bonding ability and both mechanical and chemical behavior of demineralized dentin infiltrated with polymeric nanoparticles doped with dexamethasone (Dex-NPs).

METHODS

Dentin conditioned surfaces were infiltrated with NPs, Dex-NPs or Dex-Zn-NPs. Bonded interfaces were also created and stored for 24 h or 21d, and then submitted to microtensile bond strength testing. Dentin remineralization was analyzed by Nanohardness, Young's modulus and Raman analysis.

RESULTS

At 21d of storage, dentin treated with undoped-NPs attained the lowest nanohardness and Young's modulus. Dex-NPs and Zn-Dex-NPs increased dentin nanohardness and Young's modulus after 21d Raman analysis showed high remineralization, crystallinity, crosslinking and better structure of collagen when functionalized Dex-NPs were present at the dentin interface.

CONCLUSIONS

Infiltration of dentin with Dex-NPs promoted functional remineralization as proved by nanomechanical and morpho-chemical evaluation tests. Dexamethasone in dentin facilitated crystallographic maturity, crystallinity and improved maturity and secondary structure of dentin collagen.

CLINICAL SIGNIFICANCE

Using dexamethasone-functionalized NPs before resin infiltration is a clear option to obtain dentin remineralization, as these NPs produce the reinforcement of the dentin structure, which will lead to the improvement of the longevity of resin restorations.

The impact of different alignment strategies on bone cuts in total knee arthroplasty for varus knee phenotypes

PURPOSE

The purpose of this study was to visualise the influence of alignment strategy on bone resection in varus knee phenotypes. The hypothesis was that different amounts of bone resection would be required depending on the alignment strategy chosen. Through visualisation of the corresponding bone sections, it was hypothesised, it would be possible to assess which of the different alignment strategies would require the least amount of change to the soft tissues for the chosen phenotype, whilst still ensuring acceptable alignment of the components, and thus could be considered the most ideal alignment strategy.

METHODS

Simulations of the different alignment strategies (mechanical, anatomical, constrained kinematic and unconstrained kinematic) in relation to their bone resections were performed on five common exemplary varus knee phenotypes. VAR_HKA174° VAR_FMA87° VAR_TMA84°, VAR_HKA174° VAR_FMA90° NEU_TMA87°, VAR_HKA174° NEU_FMA93° VAR_TMA84°, VAR_HKA177° NEU_FMA93° NEU_TMA87° and VAR_HKA177° VAL_FMA96° VAR_TMA81°. The phenotype system used categorises knees based on overall limb alignment (i.e. hip knee angle) but also takes into account joint line obliquity (i.e. TKA and FMA) and has been applied in the global orthopaedic community since its introduction in 2019. The simulations are based on long-leg radiographs under load. It is assumed that a change of 1° in the alignment of the joint line corresponds to a displacement of the distal condyle by 1 mm.

RESULTS

In the most common phenotype VAR_HKA174° NEU_FMA93° VAR_TMA84°, a mechanical alignment would result in an asymmetric elevation of the tibial medial joint line by 6 mm and a lateral distalisation of the femoral condyle by 3 mm, an anatomical alignment only by 0 and 3 mm, a restricted by 3 and 3 mm, respectively, whilst a kinematic alignment would result in no change in joint line obliquity. In the similarly common phenotype 2 VAR_HKA174° VAR_FMA90° NEU_TMA87° with the same HKA, the changes are considerably less with only 3 mm asymmetric height change on one joint side, respectively, and no change in restricted or kinematic alignment.

CONCLUSION

This study shows that significantly different amounts of bone resection are required depending on the varus phenotype and the alignment strategy chosen. Based on the simulations performed, it can, therefore, be assumed that an individual decision for the respective phenotype is more important than the dogmatically correct alignment strategy. By including such simulations, the modern orthopaedic surgeon can now avoid biomechanically inferior alignments and still obtain the most natural possible knee alignment for the patient.

The end-tidal alveolar dead space fraction for risk stratification during the first week of invasive mechanical ventilation: an observational cohort study

BACKGROUND

The end-tidal alveolar dead space fraction (AVDSf = [PaCO₂-P_ETCO₂]/PaCO₂) is a metric used to estimate alveolar dead space. Higher AVDSf on the first day of mechanical ventilation is associated with mortality and fewer ventilator-free days. It is not clear if AVDSf is associated with length of ventilation in survivors, how AVDSf performs for risk stratification beyond the first day of ventilation, or whether AVDSf adds predictive value to oxygenation (oxygenation index [OI]) or severity of illness (Pediatric Risk of Mortality [PRISM III]) markers.

METHODS

Retrospective single-center observational cohort study of children and young adults receiving invasive mechanical ventilation. In those with arterial or capillary blood gases, AVDSf was calculated at the time of every blood gas for the first week of mechanical ventilation.

RESULTS

There were 2335 children and young adults (median age 5.8 years [IQR 1.2, 13.2]) enrolled with 8004 analyzed AVDSf values. Higher AVDSf was associated with mortality and longer length of ventilation in survivors throughout the first week of ventilation after controlling for OI and PRISM III. Higher OI was not associated with increased mortality until ≥ 48 h of ventilation after controlling for AVDSf and PRISM III. When using standardized variables, AVDSf effect estimates were generally higher than OI for mortality, whereas OI effect estimates were generally higher than AVDSf for the length of ventilation in survivors. An AVDSf > 0.3 was associated with a higher mortality than an AVDSf < 0.2 within each pediatric acute respiratory distress syndrome severity category. The maximum AVDSf within 12 h of intensive care unit admission demonstrated good risk stratification for mortality (AUC 0.768 [95% CI 0.732, 0.803]). AVDSf did not improve mortality risk stratification when added to PRISM III but did improve mortality risk stratification when added to the gas exchange components of PRISM III (minimum 12-h PaO₂ and maximum 12-h PCO₂) (p < 0.00001).

CONCLUSIONS

AVDSf is associated with mortality and length of ventilation in survivors throughout the first week of invasive mechanical ventilation. Some analyses suggest AVDSf may better stratify mortality risk than OI, whereas OI may better stratify risk for prolonged ventilation in survivors than AVDSf.

Enhancing mechanical and photocatalytic properties by surface microstructure regulation of TiO2 nanofiber membranes

In this work, TiO₂ nanofiber membrane (NFM) with a complete surface microstructure was prepared through regulating the surface microstructure of TiO₂ NFM by doping Zr. The crystal structures and morphological analyses indicated that the nanofiber membranes were consisted by disordered accumulation of Zr-doped TiO₂ nanofibers with a crack-free surface, small grain size and high aspect ratio. When the doping amount of Zr was 0.8 mL, the tensile strength of the doped membranes reached 1.27 MPa, which was 60.7% higher than that of pure TiO₂ NFM. The photocatalytic performance of Zr-doped TiO₂ NFM was evaluated by the degradation performance of Methylene orange (MO) under simulated sunlight irradiation. Compared with the undoped TiO₂ NFM, the 0.8-Zr/TiO₂ NFM presented a higher catalytic degradation efficiency (improved by 69.6%), and the photocatalytic performance maintained stable after five circulating. It was found that the doping of Zr ions effectively limited the surface crack size and grain size of TiO₂ nanofibers, thereby improving the tensile strength, and enhanced the surface area effect and carrier transfer efficiency of TiO₂ NFM. On the other hand, a narrow band-gap was obtained by doping a small amount of Zr ions, which expanded the visible light response range to improve the photocatalytic performance of TiO₂ nanofibers.

Investigation of the flocculating activity of oyster shell powders on Microcystis aeruginosa with varying particle size and mechanical conditions

Harmful algal blooms have been a serious environmental problem. The flocculation of Microcystis aeruginosa by oyster shell powders prepared by aerobic calcination (CO), anaerobic calcination (CN), acidification anaerobic calcination (CAN), and deacetylation anaerobic calcination (CHN) was studied. The CO800 (100 mesh) and CN800 (160 mesh) presented the highest flocculation rate of 89.46% and 77.39% when they were stirred for 1 min with speed of 750 r/min and 250 r/min, respectively. The photosynthesis and viability of the algae cells flocculated by CO800 with particle size of 100 mesh were not significantly damaged. The phosphorus nutrient could be removed by CO800 and CN800 effectively due to the presence of Ca²⁺, which also limited Microcystis aeruginosa growth. The study showed that the processing of oyster shell powder could be used as an effective flocculating material.

A comprehensive correlated analysis of Ra-Doped (ZnO2, ZnO) for optoelectronic applications: a first-principle study

CONTEXT

Zinc oxide (ZnO) exhibits bulk-like behavior and is modified by radium doping to attain favorable electronic properties. The elastic and mechanical response of ZnO₂ is much more favorable than ZnO material. The change in thermal expansion, Debye temperature, free energy, entropy, and specific heat leads it to be a good candidate for thermodynamic applications at low and high temperatures. Optical properties like dielectric function, absorption, refraction, reflection, and refractive index obtained after suitable doping transform the material as optically active. ZnO₂ has low reflectivity and zero absorption below the electronic band gap as compared to ZnO in a wider spectral range. Our analyses on doped ZnO₂ and ZnO make us confident for a wide range of applications in optoelectronic and anti-bacterial treatment in biomedical devices. Especially due to high flexibility and high light transmission, ZnO₂ is an excellent applicant for transparent electrodes.

METHODS

Density functional theory has been employed in consistency with generalized gradient approximation (GGA) with PBEsol to analyze the structural, electronic, elastic, mechanical, thermodynamic, and optical response of pure and Ra-doped (ZnO₂ and ZnO) materials.

Kinematic alignment results in clinically similar outcomes to mechanical alignment: Systematic review and meta-analysis

PURPOSE

It is unclear whether a difference in functional outcome exists between kinematically aligned (KA) and mechanically aligned (MA) knee replacements. The aim of this study is to perform a comprehensive systematic review and meta-analysis of the available level I-IV evidence.

METHODS

A meta-analysis of randomised controlled trials and observational studies comparing patient reported outcome measures (PROMs), range of motion (ROM), gait analysis and complications in TKA with KA and MA was performed. Quality assessment was performed for each study using the Joanna Briggs Institute (JBI) critical appraisal tools.

RESULTS

Twelve randomised controlled trials and fourteen observational studies published between 2014 and 2022 were included in the final analysis. Meta-analysis revealed KA to have significantly better Oxford Knee Score (OKS) (p = 0.02), Forgotten Joint Score (FJS) (p = 0.006), Knee Society Score (KSS) Objective Knee (p = 0.03) and KSS Functional Activity (p = 0.008) scores. However, these improvements did not exceed the minimum clinically important difference (MCID) values reported in the literature. Subgroup analysis showed robotic assisted KA-TKA to have a clinically superior FJS (p = 0.0002) and trend towards KSS Objective Knee score (p = 0.10), compared to PSI. Gait and plantar pressure distribution of KA cohorts more closely represented healthy cohorts, and KA showed a weak association of a decreased knee adduction moment (KAM) compared to MA. Differences in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), range of motion and complications were not significant between groups.

CONCLUSION

Although KA results in several improved functional outcomes, these do not reach clinical significance. Further standardised large-scale randomised studies are required to improve the quality of evidence. As it stands, it is difficult to recommend one philosophy over the other.

One session of 20 ​N cyclic compression induces chronic knee osteoarthritis in rats: A long-term study

Objective

Mechanical stimulation is a risk factor for knee osteoarthritis. Non-surgical compression has been used to study the effects of mechanical stimulation in vivo. However, the long-term effects of low-force compression on knee joint had not been studied. Therefore, we sought to identify the long-term effects of low-force cyclic compression on the rat knee joint.

Design

In this study, we applied one session cyclic compression with a peak load of 20 ​N for 60 cycles to the rat knee joint in an approximately 140-degree flexion position (Wistar, male, 12 weeks old), followed by 1 year of observation (including data from 1 week, 2 weeks, 4 weeks, 8 weeks, 6 months, and 1 year after compression), and then performed a sub-regional analysis with hematoxylin-eosin, Safranin O and Fast Green, and MMP13 immunohistochemical staining.

Results

We observed osteoarthritis-like cartilage damage, synovial inflammation, and high expression of MMP13 within 1 year after compression. However, these changes progressed slowly, with obvious matrix cracks that did not appear until 1 year after compression. In the regional analysis, we found that low-force compression caused a much slower development of injury at the compression contact site, and no significant structural cartilage damage was observed after 1 year of compression. In contrast, the non-contact site during compression at tibial cartilage in the same joint was the first to show significant structural damage.

Conclusion

This study demonstrates that one session of 20 ​N cyclic compression induces a chronic osteoarthritis-like phenotype in the rat knee in the long term.

The impact of different alignment strategies on bone cuts for neutral knee phenotypes in total knee arthroplasty

PURPOSE

The purpose of this study was to simulate and visualise the influence of the alignment strategy on bone resection in neutral knee phenotypes. It was hypothesised that different amounts of bone resection would be required depending on the alignment strategy chosen. The hypothesis was that by visualising the corresponding bone cuts, it would be possible to assess which of the different alignment strategies required the least change to the soft tissues for the chosen phenotype but still ensured acceptable component alignment and could, therefore, be considered the most ideal alignment strategy.

METHODS

Simulations of the different alignment strategies (mechanical, anatomical, restricted kinematic and unrestricted kinematic) regarding their bone resections were performed on four common exemplary neutral knee phenotypes. NEU_HKA0° VAR_FMA 90° VAL_TMA90°, NEU_HKA0° NEU_FMA 93° NEU_TMA87°, NEU_HKA0° VAL_FMA 96° NEU_TMA87° and NEU_HKA0° VAL_FMA 99° VAR_TMA84°. The phenotype system used categorises knees based on overall limb alignment (i.e. hip knee angle) but also considers joint line obliquity (i.e. TKA and FMA) and has been used globally since its introduction in 2019. These simulations are based on long leg weightbearing radiographs. It is assumed that a change of 1° in the alignment of the joint line corresponds to correspond to 1 mm of distal condyle offset.

RESULTS

In the most common neutral phenotype NEU_HKA0° NEU_FMA 93° NEU_TMA87°, with a prevalence of 30%, bone cuts remain below 4 mm regardless of alignment strategy. The greatest changes in the obliquity of the joint line can be expected for the mechanical alignment of the phenotype NEU_HKA0° VAL_FMA 99° VAR_TMA84° where the medial tibia is raised by 6 mm and the lateral femur is shifted distally by 9 mm. In contrast, the NEU_HKA0° VAR_FMA 90° VAL_TMA90° phenotype requires no change in joint line obliquity if the mechanical alignment strategy is used.

CONCLUSION

Illustrations of alignment strategies help the treating surgeon to estimate the postoperative joint line obliquity. When considering the alignment strategy, it seems reasonable to prefer a strategy where the joint line obliquity is changed as little as possible. Although for the most common neutral knee phenotype the choice of alignment strategy seems to be of negligible importance, in general, even for neutral phenotypes, large differences in bone cuts can be observed depending on the choice of alignment strategy.

Mechanical Thrombectomy for M2 Segment Occlusion in Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

The safety and benefit of mechanical thrombectomy (MT) in the treatment of acute ischemic stroke (AIS) patients with M2 segment middle cerebral artery occlusions remain uncertain.

OBJECTIVE

To investigate the benefit of mechanical thrombectomy for M2 occlusion compared with M1 occlusion in patients with AIS.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched from inception to April 2021 to identify relevant articles. The main results comprised 90-day functional independence (modified Rankin Score from 0-2), successful recanalization (thrombectomy in cerebral infarction [TICI] 2b/3), mortality, and rates of symptomatic intracerebral hemorrhage after using modern thrombectomy devices. Odds ratios (ORs) were generated for binary variants. ReviewManager 5.3 software was used.

RESULTS

Ultimately, a total of 14 trials were included, with 3454 participants enrolled. MT for M2 occlusion had a higher rate of 3-month functional independence than M1 occlusion, but the difference was nonsignificant (OR: 1.19, 95% confidence interval [CI]: 0.98 to 1.46). The TICI2b/3 scores (OR: 0.71, 95% CI: 0.58-0.88) in M2 occlusion were remarkably lower than those in M1. The mortality and symptomatic intracerebral hemorrhage rates were comparable between the 2 groups. When comparing M2 and M1 occlusions, we found that there was no significant difference between stent retriever and aspiration in the modified Rankin Score (0-2) after AIS, but aspiration exerted an eminently higher recanalization rate with regard to TICI2b/3 (OR: 0.77, 95% CI: 0.61-0.96).

CONCLUSIONS

Compared with M1 occlusion, patients with M2 occlusion treated by MT demonstrated similar clinical outcomes in this study. Moreover, there was no difference between stent retriever and aspiration in treating M2 occlusion in terms of functional independence at 90 days. However, aspiration exerted a conspicuously higher recanalization rate in M2 occlusion than in M1 occlusion.

Experimental characterisation and modelling of breast Cooper's ligaments

The aim of this study was to characterise the mechanical behaviour of Cooper's ligaments. Such ligaments are collagenous breast tissue that create a three-dimensional structure over the entire breast volume. Ten ligaments were extracted from a human cadaver, from which 28 samples were cut and used to perform uniaxial tensile tests. Histological analysis showed that the main direction of the fibres visible to the naked eye corresponds to the orientation of the fibres on a microscopic scale. The specimens were cut according to this orientation, which allowed the sample to be stretched in the main fibre direction. From these experimental stretch/stress curves, an original anisotropic hyperelastic constitutive law is proposed to model the behaviour of Cooper's ligaments and the material parameter validity is discussed.

Exercise to Mend Aged-tissue Crosstalk in Bone Targeting Osteoporosis & Osteoarthritis

Aging induces alterations in bone structure and strength through a multitude of processes, exacerbating common aging- related diseases like osteoporosis and osteoarthritis. Cellular hallmarks of aging are examined, as related to bone and the marrow microenvironment, and ways in which these might contribute to a variety of age-related perturbations in osteoblasts, osteocytes, marrow adipocytes, chondrocytes, osteoclasts, and their respective progenitors. Cellular senescence, stem cell exhaustion, mitochondrial dysfunction, epigenetic and intracellular communication changes are central pathways and recognized as associated and potentially causal in aging. We focus on these in musculoskeletal system and highlight knowledge gaps in the literature regarding cellular and tissue crosstalk in bone, cartilage, and the bone marrow niche. While senolytics have been utilized to target aging pathways, here we propose non-pharmacologic, exercise-based interventions as prospective "senolytics" against aging effects on the skeleton. Increased bone mass and delayed onset or progression of osteoporosis and osteoarthritis are some of the recognized benefits of regular exercise across the lifespan. Further investigation is needed to delineate how cellular indicators of aging manifest in bone and the marrow niche and how altered cellular and tissue crosstalk impact disease progression, as well as consideration of exercise as a therapeutic modality, as a means to enhance discovery of bone-targeted therapies.