Hierarchical structure formation by crystal growth-front instabilities during ice templating.

Directional solidification of aqueous solutions and slurries in a temperature gradient is widely used to produce cellular materials through a phase separation of solutes or suspended particles between growing ice lamellae. While this process has analogies to the directional solidification of metallurgical alloys, it forms very different hierarchical structures. The resulting honeycomb-like porosity of freeze-cast materials consists of regularly spaced, lamellar cell walls which frequently exhibit unilateral surface features of morphological complexity reminiscent of living forms, all of which are unknown in metallurgical structures. While the strong anisotropy of ice-crystal growth has been hypothesized to play a role in shaping those structures, the mechanism by which they form has remained elusive. By directionally freezing binary water mixtures containing small solutes obeying Fickian diffusion, and phase-field modeling of those experiments, we reveal how those structures form. We show that the flat side of lamellae forms because of slow faceted ice-crystal growth along the c-axis, while weakly anisotropic fast growth in other directions, including the basal plane, is responsible for the unilateral features. Diffusion-controlled morphological primary instabilities on the solid-liquid interface form a cellular structure on the atomically rough side of the lamellae, which template regularly spaced "ridges" while secondary instabilities of this structure are responsible for the more complex features. Collating the results, we obtain a scaling law for the lamellar spacing,  [Formula: see text] , where [Formula: see text] and [Formula: see text] are the local growth rate and temperature gradient, respectively.

A Hierarchical Hydrogel Impregnation Strategy Enables Brittle-Failure-Free 3D-Printed Bioceramic Scaffolds.

3D-printed bioceramic scaffolds offer great potential for bone tissue engineering (BTE) but their inherent brittleness and reduced mechanical properties at high porosities can easily result in catastrophic fractures. Herein, this study presents a hierarchical hydrogel impregnation strategy, incorporating poly(vinyl alcohol) (PVA) hydrogel into the macro- and micropores of bioceramic scaffolds and synergistically reinforcing it via freeze-casting assisted solution substitution (FASS) in a tannic acid (TA)-glycerol solution. By effectively mitigating catastrophic brittle failures, the hydrogel-impregnated scaffolds showcase three- and 100-fold enhancement in mechanical energy absorption under compression (5.05 MJ m-3) and three-point bending (3.82 MJ m-3), respectively. The reinforcement mechanisms are further investigated by experimental and simulation analyses, revealing a multi-scale synergy of fracture and fragmentation resistance through macro and micro-scale fiber bridging, and nano and molecular-scale hydrogel reinforcement. Also, the scaffolds acquire additional antibacterial and drug-loading capabilities from the hydrogel phase while maintaining favorable cell biocompatibility. Therefore, this study demonstrates a facile yet effective approach for preparing brittle-failure-free bioceramic scaffolds with enhanced biological functionalities, showcasing immense potential for BTE applications.

Tungsten Strongly Inhibits Sintering of Porous Iron During High-Temperature Redox Cycling.

Freeze-cast Fe-25 W (at%) lamellar foams show excellent resistance to degradation at 800 °C during steam-hydrogen redox cycling between the metallic and oxide states, with fast reaction kinetics maintained up to at least 100 redox cycles with full Fe utilization. This very high stability stems from the sintering inhibition of W combined with the freeze-cast architecture and the chemical vapor transport (CVT) mechanism of reduction. These three factors create a hierarchical porosity in the foam, consisting of i) macroscopic elongated channels, ii) micro-scale sintering inhibition pores, and iii) submicron CVT pores. Microstructural characterization via SEM and EDS is combined with in situ XRD to fully explore the phase evolution and microstructural impact of W on Fe during redox cycling. Comparison with tapped Fe-25 W (at%) powder beds reveals that the freeze-cast channels and lamellae are not critical to the performance of the material.

Soft and Damping Thermal Interface Materials with Honeycomb-Board-Mimetic Filler Network for Electronic Heat Dissipation.

High-power-density electronic devices under vibrations call for soft and damping thermal interface materials (TIMs) for efficient heat dissipation. However, integrating low hardness, high damping, and superior heat transfer capability into one TIM is highly challenging. Herein, soft, damping, and thermally conductive TIMs are designed and prepared by constructing a honeycomb-board-mimetic boron nitride nanosheet (BNNS) network in a dynamic polyimine via one-step horizontal centrifugal casting. The unique filler network makes the TIMs perform a high through-plane thermal conductivity (> 7.69 W m-1 K-1) and a uniform heat transfer process. Meanwhile, the hierarchical dynamic bonding of the polyimine endows the TIMs with low compressive strength (2.16 MPa at 20% strain) and excellent damping performance (tan δ > ≈0.3 at 10-2-102 Hz). The resulting TIMs also exhibit electrical insulation and remarkable recycling ability. Compared with the commercial ones, the TIMs provide better heat dissipation (4.1 °C) for a high-power 5G base station and less temperature fluctuation (1.8 °C) for an automotive insulated gate bipolar transistor (IGBT) under vibrations. This rational design offers a viable approach to prepare soft and damping TIMs for effective heat dissipation of high-power-density electronic devices under vibrations.

Structural, material and antibacterial properties of quercetin incorporated soy protein isolate films and its binding behavior through molecular docking.

This study aimed to investigate the three different methods for the fabrication of quercetin (1%-3% w/w of protein) incorporated soy protein isolate (SPI) films and their effect on material properties. The quercetin incorporated SPI films prepared by these methods were characterized by Fourier transform infrared (FTIR) spectroscopy, UV-Vis spectrophotometer, tensile properties, and water uptake and leaching properties. The cross-linking pattern was revealed by the FTIR spectrum that showed formation of an ester group because of interaction between the quercetin hydroxyl group and the carboxyl side chain of SPI amino acids. The tensile strength of SPI films were enhanced with the addition of quercetin as it increased to a maximum of 6.17 MPa while neat SPI film had tensile strength 4.13 MPa. The prepared films exhibit significant antibacterial activity against Listeria monocytogenes and Escherichia coli. The In-silico docking analysis demonstrates that covalent and non-covalent forces play crucial roles in binding interaction. It shows the formation of four hydrogen bonds, two salt bridges along with one pi-alkyl interaction. The simulation studies reflect the crucial amino acid residues involved in SPI-quercetin binding. The effect of quercetin binding with SPI on its stability and compactness is revealed by Root mean square deviation (RMSD) and radius of gyration studies.

Non-surgical correction of knee flexion deformity in persons with haemophilia: A staged multidisciplinary approach.

INTRODUCTION: Flexion deformity of the knee is a common complication following recurrent haemarthrosis in persons with haemophilia (PWH) on episodic factor replacement therapy, restricting independent mobility. There is limited literature on the comprehensive management of this condition. This report provides the outcome of a staged multidisciplinary approach for the correction of knee flexion deformity (KFD) even in limited resource settings. PATIENTS AND METHODS: The data of 49 consecutive PWH who were treated for KFD were analysed. The approach included graded physical therapy (PT), followed by serial casting and/or mobilisation under anaesthesia (MUA). MUA was done in carefully selected knees. Surgical correction was opted when non-surgical methods failed. RESULTS: Of the 49 patients (55 knees), with a median KFD of 40 degrees (range: 10-90), 26/55 (47%) were corrected by graded PT. With serial casting, 9/19 (47%) knees had their KFD corrected. MUA was done for 11 knees of which five achieved correction (45%). Surgical correction was required for only seven knees (12.7%). Following this approach, KFD improved from 40 degrees (range: 10-90) to 15 degrees (range: 0-40), with only minor loss of flexion from 105 (range: 60-155) to 90 degrees (range: 30-150). Out of 55 KFD, 46 (83.6%) KFD were corrected; non-surgical, 39 (70.9%) and surgery, seven (12.7%). The remaining patients (nine KFD; 16.4%) were able to achieve their functional goal despite not meeting the correction criteria. CONCLUSION: This study shows that in PWH, functionally significant KFD correction can be achieved in about 71%, through non-surgical methods, even without prophylactic factor replacement.

Analysis of microscopy techniques to measure segregation in continuous-cast steel slabs.

The accurate characterisation of centreline segregation requires precise measurements of composition variations over large length scales (10 - 1 $^{-1}$ m ${\rm {m}}$ ) across the centreline of the cast product, while having high resolution, sufficient to quantify the significant composition variations between dendrites due to microsegregation at very small length scales (10 - 5 m $^{-5}{\rm {m}}$ ). This study investigates the potential of a novel microscopy technique, named Synchrotron Micro X-ray Flurorescence (SMXRF), to generate large-scale high-resolution segregation maps from a steel sample taken from a thin slab caster. Two methods, Point Analysis and Regression Analysis, are proposed for SMXRF data calibration. By comparing with the traditional Laser-Induced Breakdown Spectroscopy (LIBS), and Electron Probe Micro Analyser (EPMA) techniques, we show that SMXRF is successful in quantitative characterisation of centreline segregation. Over large areas (e.g. 12 × $\times$ 16 mm 2 ${\rm {mm}}^2$ ) and at high resolution (10-50 µ m $\mu\text{m}$ pixel size) various techniques yield comparable outcomes in terms of composition maps and solute profiles. The findings also highlight the importance of both high spatial resolution and large field of view to have a quantitative, accurate, and efficient measurement tool to investigate segregation phenomena.

Functional characterization of biodegradable films obtained from whole Paecilomyces variotii biomass.

The indiscriminate use of petroleum-based polymers and plastics for single-use food packaging has led to serious environmental problems due the non-biodegradable characteristics. Thus, much attention has been focused on the research of new biobased and biodegradable materials. Yeast and fungal biomass are low-cost and abundant sources of biopolymers with highly promising properties for the development of biodegradable materials. This study aimed to select a preparation method to develop new biodegradable films using the whole biomass of Paecilomyces variotii subjected to successive physical treatments including ultrasonic homogenization (US) and heat treatment. Sterilization process had an important impact on the final filmogenic dispersion and mechanical properties of the films. Longer US treatments produced a reduction in the particle size and the application of an intermediate UT treatment contributed favorably to the breaking of agglomerates allowing the second US treatment to be more effective, achieving an ordered network with a more uniform distribution. Samples that were not filtrated after the sterilization process presented mechanical properties similar to plasticized materials. On the other hand, the filtration process after sterilization eliminated soluble and hydratable compounds, which produced a reduction in the hydration of the films.

Risk factors for avascular necrosis of the femoral head after developmental hip dislocation reduction surgery and construction of Nomogram prediction model.

BACKGROUND: To analyze the risk factors for the development of avascular necrosis (AVN) of the femoral head after reduction surgery in children with developmental hip dysplasia (DDH), and to establish a prediction nomogram. METHODS: The clinical data of 134 children with DDH (169 hips) treated with closure reduction or open reduction from December 2016 to December 2019 were retrospectively analyzed. Independent risk factors for AVN after DDH reduction being combined with cast external immobilization were determined by univariate analysis and multivariate logistic regression and used to generate nomograms predicting the occurrence of AVN. RESULTS: A total of 169 hip joints in 134 children met the inclusion criteria, with a mean age at surgery of 10.7 ± 4.56 months (range: 4-22 months) and a mean follow-up duration of 38.32 ± 27.00 months (range: 12-94 months). AVN developed in 42 hip joints (24.9%); univariate analysis showed that the International Hip Dysplasia Institute (IHDI) grade, preoperative development of the femoral head ossification nucleus, cartilage acetabular index, femoral head to acetabular Y-shaped cartilage distance, residual acetabular dysplasia, acetabular abduction angle exceeding 60°, and the final follow-up acetabular index (AI) were associated with the development of AVN (P < 0.05). Multivariate logistic regression analysis showed that the preoperative IHDI grade, development of the femoral head ossification nucleus, acetabular abduction angle exceeding 60°, and the final follow-up AI were independent risk factors for AVN development (P < 0.05). Internal validation of the Nomogram prediction model showed a consistency index of 0.833. CONCLUSION: Preoperative IHDI grade, preoperative development of the femoral head ossification nucleus, final AI, and acetabular abduction angle exceeding 60° are risk factors for AVN development. This study successfully constructed a Nomogram prediction model for AVN after casting surgery for DDH that can predict the occurrence of AVN after casting surgery for DDH.

Clinically Significant Treatment Delay in Pediatric Scaphoid Fractures.

PURPOSE: Pediatric scaphoid fractures present to treatment in a delayed manner 8% to 29% of the time. The indications for cast immobilization in this population are not clear. The definition of a clinically important treatment delay is based only on anecdotal reports. Successful treatment with a cast may be more desirable than surgical intervention. However, it remains unclear what clinical and radiographic factors may predict success with casting. METHODS: A retrospective analysis of all scaphoid fractures treated at a single pediatric hospital was performed to identify fracture characteristics, the presence of cystic change, treatment method, and healing rate. A cut-point analysis was performed to determine the number of days of treatment delay, predictive of casting failure. Kaplan-Meier assessments were performed to determine the differences in time in cast. Characteristics of the delayed group were described and stratified by treatment success or failure. RESULTS: After review, 254 patients met the inclusion criteria. Cut-point analysis determined that a presentation delay of ≥21 days was associated with failure to unite with casting. The median time in the cast for the acute and delayed groups was not significantly different. The casting union rate of delayed fractures was less than acute fractures (75.0% vs 97.0%). CONCLUSIONS: Delayed presentation of scaphoid fractures 21 days or more after injury predicts a greater risk of casting failure; however, the union rate remains high with comparable time in cast. Cast immobilization for scaphoid fractures presenting 21 days or more after injury is a reasonable option. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognosis IV.

A model for diabetic foot ulcer clinical trials on advanced therapies.

DECLARATION OF INTEREST: TS is a consultant for Inotec AMD Ltd., UK. The authors have no other conflicts of interest to declare.

Playing Flappy Bird Based on Motion Recognition Using a Transformer Model and LIDAR Sensor.

A transformer neural network is employed in the present study to predict Q-values in a simulated environment using reinforcement learning techniques. The goal is to teach an agent to navigate and excel in the Flappy Bird game, which became a popular model for control in machine learning approaches. Unlike most top existing approaches that use the game's rendered image as input, our main contribution lies in using sensory input from LIDAR, which is represented by the ray casting method. Specifically, we focus on understanding the temporal context of measurements from a ray casting perspective and optimizing potentially risky behavior by considering the degree of the approach to objects identified as obstacles. The agent learned to use the measurements from ray casting to avoid collisions with obstacles. Our model substantially outperforms related approaches. Going forward, we aim to apply this approach in real-world scenarios.

Scalable Fast-Charging Aligned Battery Electrodes Enabled by Bidirectional Freeze-Casting.

Over the past few years, lithium-ion batteries have been extensively adopted in electric transportation. Meanwhile, the energy density of lithium-ion battery packs has been significantly improved, thanks to the development of materials science and packing technology. Despite recent progress in electric vehicle cruise ranges, the increase in battery charging rates remains a pivotal problem in electrodes with commercial-level mass loadings. Herein, we develop a scalable strategy that incorporates bidirectional freeze-casting into the conventional tape-casting method to fabricate energy-dense, fast-charging battery electrodes with aligned structures. The vertically lamellar architectures in bidirectional freeze-cast electrodes can be roll-to-roll calendered, forming the tilted yet aligned channels. These channels enable directional pathways for efficient lithium-ion transport in electrolyte-filled pores and thus realize fast-charging capabilities. In this work, we not only provide a simple yet controllable approach for building the aligned electrode architectures for fast charging but also highlight the significance of scalability in electrode fabrication considerations.

Eco-Friendly Inorganic Binders: A Key Alternative for Reducing Harmful Emissions in Molding and Core-Making Technologies.

Many years of foundry practice and much more accurate analytical methods have shown that sands with organic binders, in addition to their many technological advantages, pose risks associated with the emission of many compounds, including harmful ones (e.g., formaldehyde, phenol, benzene, polycyclic aromatic hydrocarbons, and sulfur), arising during the pouring of liquid casting alloys into molds, their cooling, and knock-out. The aim of this research is to demonstrate the potential benefits of adopting inorganic binders in European iron foundries. This will improve the environmental and working conditions by introducing cleaner and more ecological production methods, while also ranking the tested binders studied in terms of their harmful content. The article pays special attention to the analysis of seven innovative inorganic binders and one organic binder, acting as a reference for emissions of gases from the BTEX (benzene, toluene, ethylbenzene, and xylenes) and PAHs (polycyclic aromatic hydrocarbons) groups and other compounds such as phenol, formaldehyde, and isocyanates (MDI and TDI) generated during the mold pouring process with liquid metals. The knowledge gained will, for the first time, enrich the database needed to update the Reference Document on The Best Available Techniques for the Smitheries and Foundries Industry (SF BREF).

A Novel Fabrication of Heterogeneous Saponified Poly(Vinyl Alcohol)/Pullulan Blend Film for Improved Wound Healing Application.

In this study, a novel film of poly(vinyl alcohol) (PVA)/pullulan (PULL) with improved surface characteristics was prepared from poly(vinyl acetate) (PVAc)/PULL blend films with various mass ratios after the saponification treatment in a heterogeneous medium. According to proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared, and X-ray diffraction results, it was established that the successful fabrication of saponified PVA/PULL (100/0, 90/10, and 80/20) films could be obtained from PVAc/PULL (100/0, 90/10, and 80/20) films, respectively, after 72 h saponification at 50 °C. The degree of saponification calculated from 1H-NMR analysis results showed that fully saponified PVA was obtained from all studied films. Improved hydrophilic characteristics of the saponified films were revealed by a water contact angle test. Moreover, the saponified films showed improved mechanical behavior, and the micrographs of saponified films showed higher surface roughness than the unsaponified films. This kind of saponified film can be widely used for biomedical applications. Moreover, the reported saponified film dressing extended the lifespan of dressing as determined by its self-healing capacity and considerably advanced in vivo wound-healing development, which was attributed to its multifunctional characteristics, meaning that saponified film dressings are promising candidates for full-thickness skin wound healing.

Seating accuracy of removable partial denture frameworks fabricated by different digital workflows in comparison to conventional workflow.

PURPOSE: To evaluate the seating accuracy of removable partial denture (RPD) frameworks fabricated by two digital workflows involving selective laser melting (SLM) in comparison to the conventional workflow. MATERIALS AND METHODS: A Kennedy class III modification 1 partially edentulous mandibular arch was used as a master model. Three RPD framework groups were included: (1) a conventional workflow group with conventional impression and casting (CC), (2) a partial digital workflow group with conventional impression and digital fabrication (CD), and (3) a complete digital workflow group with digital impression and digital fabrication (DD). A total of 10 frameworks were produced for each group. The marginal gaps at the occlusal rests, retention arms, and reciprocating arms were measured by a traveling microscope. The data were analyzed with the one-way analysis of variance test. RESULTS: At the framework level, the most superior fit was observed for the CD group (79.5 µm) followed by DD (85.3 µm) and CC (114.2 µm) groups. The CD and DD groups were significantly superior to CC (p < 0.001). This fit pattern was consistent for the retention and reciprocating arms, while the occlusal rest fit was similar among all the groups. CONCLUSIONS: The SLM frameworks had a promising seating accuracy in comparison to conventional frameworks. The type of impression, conventional or digital, did not affect the accuracy of SLM frameworks. The differences observed in the present study are likely to be of minimal clinical significance.

Identifying and documenting osseous trauma from shark attacks by post mortem CT examination and autopsy.

A 15-year-old male was attacked by a large white shark while surfing. CT examination revealed an above-knee amputation of the right lower extremity with stripping of soft tissues from the groin distally. 3-dimensional volume rendering did not show any fragments of shark teeth but did reveal linear gouges, areas of shaving of cortical bone and an inverted 'V'-shaped defect at the distal margin of the femoral shaft. At autopsy these injuries were confirmed in addition to areas with fine parallel cross-striations matching the marginal serrations of the teeth of a white shark. Thus, while post mortem CT with 3-dimensional reconstruction at high resolution can show the nature and number of the bony injuries following shark attack, it is complimented by pathological examination which may find fine parallel grooves from teeth serrations. Post mortem 3-dimensional volume rendering may also help to find or exclude fragments of teeth, and silicone casting may provide a permanent record of bone lesions.

Plant betalains-mixed active/intelligent films for meat freshness monitoring: A review of the fabrication parameters.

The plant pigments called betalains are nutritionally safe polar compounds. They are subdivided into betaxanthins (having orange to yellow hues) and betacyanins (purple to red violet hues). Betacyanins change color with a change in pH, particularly in the range 6-8 and 9-11. Perishable foods like fish, chicken, beef, pork, and others tend to release total volatile base-nitrogen (TVB-N) during storage or deterioration, which leads to a change in the pH of pH-sensitive materials in the vicinity. pH-sensitive pigment-incorporated polymeric films with inherent active properties (or active/intelligent films) are increasingly being studied as an alternative to synthetic pH indicators to detect the accumulation of TVB-N by changing its color to indicate the stage of perishable food spoilage. There are many methods of developing such films under different conditions using different bio-based biodegradable polymer(s) and biocompatible plasticizer combinations. Among the reported methods, solution casting method has been the preferred one in most studies covered in this review. This method can be carried out under mild conditions. As such, betacyanins-incorporated polymeric films essentially require mild processing conditions because of their heat sensitivity, which will invariably affect the performance in food freshness monitoring. In this review, film fabrication parameters like temperature and duration of dissolution of polymers, plasticizer concentration, pH of the film-forming solution, film drying, and conditioning/aging, have been critically appraised based on the available literature. The lack of studies on the safety of active/intelligent films has been systematically highlighted in this review to focus future studies on this area.

A prospective randomized control trial comparing outcomes of casting, pinning, and plating for distal end of radius fractures (AO type A2, A3, C1, or C2) in the elderly population.

PURPOSE: With this prospective randomized control trial (RCT), we aim to provide the outcome analyses of the three most used treatment modalities for distal end of radius (DER) fracture management in the elderly. METHODS: A prospective randomized control trial was performed. Fifty-two patients with DER fractures (AO A2, A3, C1, or C2) were randomized to the casting (n = 17), percutaneous pinning (n = 18), and the volar plating group (n = 17). Radiological measurements measured were radial inclination (RI), radial height (RH), volar tilt (VT), and ulnar variance (UV). The outcome was measured based on range-of-motion, grip strength, Patient-Related-Wrist-Evaluation (PRWE) score, and the Quick-Disabilities-of-the-Arm-Shoulder-Hand (QDASH) score. RESULTS: Immediate post-operative and 1-year-follow-up X-rays showed a significant difference measurement between the groups (p < 0.05). Pairwise comparisons of the casting and pinning groups (p < 0.05) and the casting and plating groups (p < 0.05) revealed significant differences at the 1-year follow-up, but not the pinning and plating groups (p > 0.05). The analysis found significant differences in clinical outcomes after 1 month of follow-up, with the plating group outperforming the other two (p > 0.05). However, after a year of follow-up, all groups had comparable outcomes; however, the plating group showed improved palmar flexion (p < 0.001), radial deviation (p < 0.001), and a lower PRWE score (p < 0.05), indicating better wrist function. Complications were more in casting group. CONCLUSION: The study found a radiologically significant difference between groups throughout the follow-up, but it did not affect functional results. Clinical outcomes were similar across the groups, with plating showing better palmar flexion and radial deviation. Grip strength was also better in the plating group, but statistically insignificant. The study suggests plating should be chosen over other treatments for high-demand patients.

High Thermoelectric Performance Related to PVDF Ferroelectric Domains in P-Type Flexible PVDF-Bi0.5 Sb1.5 Te3 Composite Film.

There is increasing demand to power Internet of Things devices using ambient energy sources. Flexible, low-temperature, organic/inorganic thermoelectric devices are a breakthrough next-generation approach to meet this challenge. However, these systems suffer from poor performance and expensive processing preventing wide application of the technology. In this study, by combining a ferroelectric polymer (Polyvinylidene fluoride (PVDF, ß phase)) with p-type Bi0.5 Sb1.5 Te3 (BST) a thermoelectric composite film with maximum is produced power factor. Energy filter from ferroelectric-thermoelectric junction also leads to high Seebeck voltage ≈242 µV K-1 . For the first time, compelling evidence is provided that the dipole of a ferroelectric material is helping decouple electron transport related to carrier mobility and the Seebeck coefficient, to provide 5× or more improvement in thermoelectric power factor. The best composition, PVDF/BST film with BST 95 wt.% has a power factor of 712 µW•m-1  K-2 . A thermoelectric generator fabricated from a PVDF/BST film demonstrated Pmax T 12.02 µW and Pdensity 40.8 W m-2 under 50 K temperature difference. This development also provides a new insight into a physical technique, applicable to both flexible and non-flexible thermoelectrics, to obtain comprehensive thermoelectric performance.