Ion beam sputtering coatings on large substrates: toward an improvement of the mechanical and optical performances

Large mirrors (?350 mm) having extremely low optical loss (absorption, scattering, wavefront) were coated for the VIRGO interferometer. The new generation of mirrors needs to have a better wavefront and lower mechanical loss. To improve the component wavefront, the corrective coating technique was used. By doping the tantalum pentoxide layers, we improved, for the first time to our knowledge, the multilayer mechanical loss. The first results are discussed.     

Effect of post-mortem conditioning of ewe carcasses on instrumental texture profile of cooked thigh muscles

The semimembranosus (SM) and semitendinosus (ST) muscles were removed from 18 four to five year old Bannur breed ewes which were slaughtered and carcasses (six each) suspended by the (a) Achilles tendon at 26 ± 2°C for 1 h before cutting (b) Achilles tendon at 2-3°C for 42 h and (c) Pelvis at 26 ± 2°C for 7 h followed by chilling at 2-3°C for 17 h. The muscles were cooked by boiling in a water bath for 30 min or by heating in a pressure cooker for 20 min and the tenderness measured with a Warner-Bratzler tenderometer. Hardness, cohensiveness, elasticity and chewiness were also measured with a General Foods Texturometer. With conventional hanging at 2-3°C the SM muscle was the toughest and the ST muscle the most tender. By holding carcasses at 26 ± °C for 1 h before cooking there was an increased tenderness. The most tender meat was found from carcasses which were suspended by the pelvis at 26 ± °C before chilling. The increase or decrease in shear values were respectively associated with contraction or stretching of muscles effected by carcass conditioning treatments. In contrast, thermal shrinkage due to cooking had opposite effects so that greater thermal shrinkage resulted in lower shear values. The shear values from the Warner-Bratzler tenderometer did not correlate well with the parameters measured by the General Foods Texturometer.     

Effect of interdiffusion regions on penetrant flux through multilayer films

Barrier properties of polymer films can be improved in various ways, such as formation of multilayer structures by coextrusion, surface treatment, and coatings. This work explores the use of thousands of alternating layers of polymer (xyxy…) to modify the resistance to permeation. A model is presented to predict the number of layers needed in a laminate to change the flux of a permeant by a given amount. An important feature of the model is the species transport across the interdiffusion regions at the polymer‐polymer interfaces where diffusivity of the penetrant, D_i, is assumed to be a constant or a function of the volume fractions (?) of the interdiffusing polymers. For constant D_i, the modeling results show that increasing the number of interfacial regions decreases the flux for a given condition, and a large number of layers are required to achieve appreciable flux reduction. For ?‐dependent D_i a balanced interdiffusion region was modeled in which the interdiffusing polymers were assumed to interpenetrate one another equally. In this particular case, the flux was predicted to always increase with the number of layers.     

Soft,Strong, Tough,and Durable Bio-Hydrogels Via Maximizing Elastic Entropy

Load-bearing soft tissues are soft but strong, strong yet tough. These properties can only be replicated in synthetic hydrogels, which do not have the biocomplexity required by many biomedical applications. By contrast, natural hydrogels, although retaining the native complexity, are weak and fragile. Here a thermomechanical casting method is presented to achieve the mechanical capabilities of synthetic materials in biopolymer hydrogels. The thermomechanical cast and chemically crosslinked biopolymer chains form a short-range disordered but long-range ordered structure in water. Upon stretch, the disordered structure transforms to a hierarchically ordered structure. This disorder-order transformation resembles the synergy of the disordered elastin and ordered collagen in load-bearing soft tissues. As entropy drives a reverse order-disorder transformation, the hydrogels can resist repeated cycles of loads without deterioration in mechanical properties. Gelatin hydrogels produced by this method combine tissue-like tunable mechanical properties that outperform the gelatin prepared by synthetic approaches, and in vivo biocomplexity beyond current natural systems. Unlike polymer engineering approaches, which rely on specific crosslinks provided by special polymers, this strategy utilizes the entropy of swollen chains and is generalizable to many other biopolymers. It could thus significantly accelerate translational success of biomaterials.     

Varying the Directionality of Protein Catalysts for Aldol and Retro-Aldol Reactions

Natural aldolase enzymes and created retro-aldolase protein catalysts often catalyze both aldol and retro-aldol reactions depending on the concentrations of the reactants and the products. Here, we report that the directionality of protein catalysts can be altered by replacing one amino acid. The protein catalyst derived from a scaffold of a previously reported retro-aldolase catalyst, catalyzed aldol reactions more efficiently than the previously reported retro-aldolase catalyst. The retro-aldolase catalyst efficiently catalyzed the retro-aldol reaction but was less efficient in catalyzing the aldol reaction. The results indicate that protein catalysts with varying levels of directionality in usually reversibly catalyzed aldol and retro-aldol reactions can be generated from the same protein scaffold.     

Glass/Brass-270 Wire-Mesh Nanosilica Toughened Epoxy Composite: Mechanical,Impact and Fatigue Behaviour

Silicon - High toughness epoxy resin hybrid composites were prepared using nanosilica, glass fibre and brass wire-mesh. The main aim of this research was to study the effect of adding nanosilica...     

Mitigating the Effect of COVID Lockdown Period on Channel and Bandwidth Utilization in Mobile Communication Network in North Western Rajasthan (India)

Wireless Personal Communications - The COVID-19 lockdown has led all the citizens (mobile subscribers) of India to stay at home and rather work from home. The people have started consuming more...     

Development of gum odina-gelatin based antimicrobial loaded biodegradable spongy scaffold: A promising wound care tool

The present study focuses on development of HPMC K100M reinforced antimicrobial loaded spongy biodegradable wound dressing scaffold by blending gum odina (GO) and gelatin (G) which has not been explored so far. All the prepared formulations by varying GO-HPMC K100M: G are subjected to physicochemical evaluations (visual appearance, swelling study, biodegradability, drug loading, and drug release). F3B (GO-HPMC K100M: G = 1:1, blank) and F3D (GO-HPMC K100M: G = 1:1, drug loaded) are optimized and selected for further evaluations. Controlled degradation and sustained release of impregnated drug molecules from F3D may influence the antimicrobial efficacy. A satisfactory result of protein adsorption on the surface of F3B and F3D (almost 24%) can be an important event for being a biomaterial. The safe value of hemolytic potentiality (approximately 4%) may consider as biocompatible in nature. Furthermore, upon other characterizations F3B and F3D can be considered as an excellent potential candidate for biomedical application.     

Quantifying Mitochondrial Dynamics in Patient Fibroblasts with Multiple Developmental Defects and Mitochondrial Disorders

Mitochondria are dynamic organelles that undergo rounds of fission and fusion and exhibit a wide range of morphologies that contribute to the regulation of different signaling pathways and various cellular functions. It is important to understand the differences between mitochondrial structure in health and disease so that therapies can be developed to maintain the homeostatic balance of mitochondrial dynamics. Mitochondrial disorders are multisystemic and characterized by complex and variable clinical pathologies. The dynamics of mitochondria in mitochondrial disorders is thus worthy of investigation. Therefore, in this study, we performed a comprehensive analysis of mitochondrial dynamics in ten patient-derived fibroblasts containing different mutations and deletions associated with various mitochondrial disorders. Our results suggest that the most predominant morphological signature for mitochondria in the diseased state is fragmentation, with eight out of the ten cell lines exhibiting characteristics consistent with fragmented mitochondria. To our knowledge, this is the first comprehensive study that quantifies mitochondrial dynamics in cell lines with a wide array of developmental and mitochondrial disorders. A more thorough analysis of the correlations between mitochondrial dynamics, mitochondrial genome perturbations, and bioenergetic dysfunction will aid in identifying unique morphological signatures of various mitochondrial disorders in the future.