Layered Titanium Carbide-Mediated Fast Shape Switching and Excellent Thermal and Electrical Transport in Shape-Memory-Polymer Composites for Smart Technologies: MAX Versus MXene

Stimuli-responsive materials can frequently tune between their temporary and original shapes, and have the potential for artificial intelligence-based technologies in robotics, aerospace, biomedical, engineering, security, etc. Shape memory polymers (SMPs) are promising for these technologies but their inadequate thermal and electrical characteristics causing slow shape recovery limit their practical applications. Herein, for the first time, comprehensively and precisely the shape memory polyurethane (PU), a promising SMP, via a variety of novel layered titanium carbides fillers, namely, Ti₂AlC (MAX₁), Ti₃AlC₂ (MAX₂), and Ti₃C₂ (MXene), is engineered. The resultant PU-composites show 30–50% faster shape recovery in different environments, 20–25% greater extent of shape recovery in the load-constrained environment, 100–125% higher thermal conductivity, and 700–16 000× higher electrical current. Importantly, the reinforcement of even a small amount of MAX and MXene (such as 0.25 wt%) has largely boosted the performance of PU. Considering ease of processability and performance enhancement factors, the MAX-phase fillers may be preferred over MXene-phase fillers for next-generation composites development. Employing PU composite component as both heat-sensor and actuator, a unique heat detector/fire alarm device that works successfully in simulated heat and fire environments is demonstrated. This work is crucial for enabling futuristic technologies.     

Preparation and characterization of ketorolac tromethamine-loaded ethyl cellulose micro-/nanospheres using different techniques

Sustained-release micro-/nanospheres of the ketorolac tromethamine (KTC) were prepared using four different techniques viz., single emulsion solvent evaporation, high pressure homogenization, spray drying, and using a microreactor. Ethyl cellulose (EC) was used as an encapsulating agent for the preparation of sustained-release micro-/nanospheres of KTC. The Plackett–Burman design was employed for design of the experiments. The resulting micro-/nanospheres were characterized for their size, morphology, encapsulation efficiency, and in vitro drug release performance. Interactions between the KTC and EC were quantified by Fourier transform infrared (FTIR) spectroscopy and X-ray powder diffractometry (XRPD). Particle morphology characterization was performed using field emission scanning electron microscopy. The micro-/nanospheres showed encapsulation efficiency of 42.34–89.33% by the solvent evaporation technique, 76.36–91.13% by the high-pressure homogenization technique, 70.74–79.68% by spray drying, and 79.00–89.49% by the microreactor technique. The micro-/nanospheres were found to be spherical and oval with smooth surface. The FTIR analysis confirmed no interaction of KTC with EC polymer. The XRPD analysis revealed good dispersion of the drug within the micro-/nanospheres formulation. Sustained KTC release profile over 12?h was achieved successfully by EC polymer. In conclusion, EC sustained-release micro-/nanospheres containing KTC can be prepared successfully using different techniques.     

Band gap and dispersive behavior of Ge alloyed a-SbSe thin films using single transmission spectrum

The transparency of SbSeGe glasses in the IR region makes them attractive candidates for low transmission loss applications. The samples of Sb₁₀Se_90−xGe_x (x = 0, 19, 21, 23, 25, 27) glasses have been prepared by melt quench technique. The thin films of these glasses have been deposited by vacuum evaporation technique. The optical study of thin films has been carried out. The refractive index, oscillator parameters, optical band gap and dielectric parameters have been calculated from optical measurements. The optical study reveals that the variation in the density of localized defect states on Ge addition affects the optical parameters of the system. The variation in concentration of localized defect states has been interpreted in terms of the change in structural network of the system.     

Electronic properties of GaP nanowires of different shapes

The electronic properties of very thin gallium phosphide nanowires of different shapes were studied by ab-initio method using the generalized gradient approximation. We consider four different shapes of nanowires viz. linear wire, zigzag wire, square wire and hexagonal wire. The geometry optimization and the stability of all nanowires were investigated. We explore the minimum energy configuration for all the structures. The present study reveals that all of the wires are stable but four atom square wires have greater stability in comparison to other structures. The analysis of density of states and band structure of optimized nanowires predicts that nanowires made from bulk GaP can be either metallic, semi-metallic, semiconducting or insulating depending upon the geometrical shape of the wire.     

Synthesis of nanocomposite gold-semiconductor materials by seed-growth method

Gold-semiconductor nanocomposite hybrid materials were synthesized by applying the seed-growth approach. Citrate stabilized gold nanoparticles were prepared by the reduction of HAuCl₄ with borohydride and used as seeds. The structural and morphological features of semiconductor materials i.e. CdS, CuS, NiS, and PbS in the presence of Au NP were examined with the help of UV-Visible spectroscopy, phase contrast microscopy, transmission electron microscopy (TEM) and X-ray diffraction measurements. The experimental results revealed that a network of semiconductor-Au NP nanocomposite material is formed in each case.     

Extended Release of Theophylline Through Sodium Alginate Hydrogel Beads: Effect of Glycerol on Entrapment Efficiency,Drug Release

Theophylline is the most useful bronchodilators for the treatment of severe reversible bronchospasm. The fluctuations of serum theophylline level in clinical practice and associated central nervous system side effects necessitate the development of an extended release formulation. In the present study, theophylline-loaded beads were prepared by extruding the dispersion of theophylline, sodium alginate, and glycerol into the cationic crosslinking solution of calcium chloride. The effect of the addition of glycerol was determined by entrapment efficiency, drug release, and morphology of beads. Absence of chemical interaction between drug, polymer, and counterions after production of beads was confirmed by Fourier transform infrared spectroscopy. Theophylline entrapment of up to 72% was achieved in beads with almost spherical shape and size ranging from 0.67 to 1.12 mm. Percentage entrapment of theophylline found to be more and release was extended up to the eleventh hour from the glycerol containing sodium alginate beads. Hence, sodium alginate glycerol beads could represent a promising oral drug delivery system to extend the release of theophylline.     

Influence of reactive compatibilizers on the rheometrical and mechanical properties of PA6/LDPE and PA6/HDPE blends

In this work, the influence of reactive compatibilizers on the rheometrical and mechanical properties of polyamide 6/low density polyethylene (PA6/LDPE) and polyamide 6/high density polyethylene (PA6/HDPE) blends was investigated. Polyethylene grafted with maleic anhydride (PEgMA), polyethylene grafted with acrylic acid (PEgAA), and ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) were used as compatibilizers. The blends were characterized by torque rheometry, mechanical properties, and morphology. Rheometrical properties results show that PEgMA and PEgAA compatibilizers are more reactive with PA6 than EMA-GMA. Mechanical properties and scanning electron microscopy analysis results show that EMA-GMA compatibilizer is as effective as PEgMA and PEgAA for PA6/LDPE blend. For PA6/HDPE blend, PEgAA and EMA-GMA compatibilizers proved to be as effective as PEgMA. For PA6/HDPE blend compatibilized with PEgAA, an intriguing “web” or “bridge” like structure was observed.     

Biomimetic synthesis of AgNPs from Penicillium chrysogenum strain FGCC/BLS1 by optimising physico‐cultural conditions and assessment of their antimicrobial potential

Biomimetic synthesis of metal nanoparticles (NPs) is safe and eco‐friendly; therefore, find diverse applications. Considering this, the soil fungi Penicillium chrysogenum strain Fungal germplasm collection centre/ BLS1 was isolated, characterized and explored to synthesize extracellular silver NPs (AgNPs) under optimised conditions. The synthesis of AgNPs was investigated using ultraviolet (UV)–visible spectroscopy, Fourier‐transform infra‐red spectroscopy (FTIR), transmission electron microscope (TEM) and dynamic light scattering (DLS) analysis. Process optimisation exhibited AgNPs synthesis within 8 h using 2 mM AgNO3 at pH 11 and temperature 70°C. TEM analysis revealed polydispersed ellipsoidal shaped AgNPs with average particle size 96.8 nm as measured by DLS. AgNPs showed negative zeta potential that confers surface stability in solution. FTIR spectra confirmed the presence of protein bound to AgNPs. Antibacterial activity against Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus by the AgNPs (100 ppm) was demonstrated by counting colony forming unit, disc diffusion, and growth kinetics assay. Additionally radial assay revealed antifungal activity of AgNPs (100 ppm) against phytopathogenic fungi Sclerotinia sclerotiorum Microbial type culture collection 8785. Furthermore, AgNPs (100 ppm) did not show any cytotoxic effects on human Red blood cells. Therefore, this novel fungal strain can be utilised for biofabrication of AgNPs under optimised conditions and have shown strong antimicrobial property.Inspec keywords: biomimetics, silver, nanoparticles, particle size, nanofabrication, nanomedicine, microorganisms, biomedical materials, antibacterial activity, light scattering, cellular biophysics, ultraviolet spectra, visible spectra, Fourier transform infrared spectra, transmission electron microscopy, pH, electrokinetic effects, proteins, molecular biophysics, biochemistry, reduction (chemical), biodiffusion, reaction kinetics, bloodOther keywords: biomimetic synthesis, physicocultural conditions, antimicrobial potential assessment, metal nanoparticles, soil fungi Penicillium chrysogenum strain FGCC/BLS1, extracellular silver NPs, ultraviolet‐visible spectroscopy, Fourier transform infrared spectroscopy, FTIR, transmission electron microscope, TEM, dynamic light scattering, process optimisation, Ag nitrate, pH, absorbance, polydispersed ellipsoidal shaped AgNPs, particle size, DLS, mycosynthesised AgNPs, negative zeta potential, surface stability, protein component, reducing agent, antibacterial activity, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, disc diffusion, colony forming unit counting, growth kinetics assay, radial assay, antifungal activity, phytopathogenic fungi Sclerotinia sclerotiorum MTCC 8785, RBC haemolysis assay, temperature 70 degC, Ag     

Asymmetric hybrid encryption scheme based on modified equal modulus decomposition in hybrid multi-resolution wavelet domain

In this paper, an asymmetric hybrid encryption scheme, using coherent superposition and modified equal modulus decomposition in a hybrid multi-resolution wavelet, is proposed. The hybrid multi-resolution wavelet is generated using fractional Fourier transform of multiple orders and Walsh transform. The fractional orders of the fractional Fourier transform increase the key space and hence provide additional strength to the cryptosystem. The designed scheme has a large key space to avoid brute-force attack and is non-linear in nature. The scheme is validated on grey-scale images. Computer-based simulations have been performed to verify the validity and performance of the proposed scheme against various attacks. Scheme's robustness to the special attack is also checked. Results show that single equal modulus decomposition with fractional Fourier transform and hybrid transform are vulnerable to the special attack, whereas the proposed scheme endures the special attack.     

Flow Control in ServerNet® Clusters

This paper investigates the performance implications of several end-to-end flow control protocols in clusters based on the ServerNet^® system-area network. The Static Window (SW) and Packet Pair (PP) flow control protocols are studied. Based on them, the Simplified Packet Pair (SPP) and the Alternating Static Window (ASW) protocols are defined. Previously, it has been proven that PP is stable for store-and-forward networks based on Rate Allocation Servers. The applicability of PP to wormhole-routing networks is studied. Simulation results for the performance characteristics are obtained and evaluated. It is shown that if high throughput is desired, ASW is the best method for controlling the average latency. On the other hand, if low throughput is acceptable, SPP can be applied to maintain low latencies.