Effect of pre-sintering temperature on the structural and dielectric properties of (Ba0.5Sr0.5)TiO3 thin films deposited by sol–gel technique

(Ba_0.5Sr_0.5)TiO₃ thin films have been deposited by sol–gel technique and the effect of pre-sintering temperature on the structural and dielectric properties has been studied. The sol was prepared from barium acetate and strontium acetate powders by dissolving them in acetic acid; while titanium isopropoxide was used as titanium source. Acetyl acetone, 2-methoxyethanol, and formamide were used as chelating agent, diluting reagent, and for getting crack free films, respectively. Two sets of films were prepared; one set pre-sintered at 400 °C while the other one at 600 °C. In all the cases, the final sintering temperature was kept fixed at 700 °C for 2 h. These films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), dielectric constant, and loss measurements and AC conductivity studies. It has been found that with an increase in the pre-sintering temperature from 400 to 600 °C, the dielectric constant increases from 225 to 383 (measured at 100 kHz); whereas, the loss tangent remains nearly constant at 0.03–0.05. The XRD results show better crystallinity and enhanced grain growth in case of films pre-sintered at 600 °C. The FTIR spectra reveals that there is significant removal of organic materials in films with higher pre-sintering temperature as compared to that with lower pre-sintering temperature. The AC conductivity studies show a decrease in the frequency exponent ‘s’ with an increase in the pre-sintering temperature which has been correlated with the reduction in oxygen vacancy densities in the sample with higher pre-sintering temperature.     

Viscoelastic behavior of formaldehyde and basic chromium sulfate‐crosslinked collagen

Rat tail tendon (RTT) collagen has been crosslinked with 1% basic chromium sulfate (BCS) at pH 3.2, and 2, 4, 8, and 10% formaldehyde (HCHO) at pH 5 and pH 8. The viscoelastic behavior (such as stress relaxation behavior for BCS and HCHO‐tanned RTT) has been studied in water and 6M urea at different temperatures. The total rate of relaxation has been divided into fast and slow components, and computed using the two‐term model and nonlinear least‐squares fit. The rate of relaxation for crosslinked RTT is less than the native one. Activation energy at absolute zero has been computed using k = AT^me/RT and nonlinear least‐squares fit. The activation energy increases for crosslinked RTT than the native one. This is consistent with the observed rate constant values. This may be due to the additional stability imparted to RTT collagen by coordinate covalent and covalent crosslinks through BCS and HCHO, respectively. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2245–2251, 1999     

Transient analysis of energy storage in a thermally stratified water tank

A one-dimensional transient heat conduction model to describe the decay of the thermocline in a stratified water tank is presented. The problem is formulated as an initial boundary value problem and the resulting governing equations in the fluid and in the storage wall are solved numerically to obtain the temperature profiles in the wall and the fluid. The formulation considers the axial conduction of heat, both in the fluid and in the solid wall. The mixing parameters introduced in the boundary conditions at the top and bottom of the tank in the fluid region account for mixing due to inlet and outlet streams with the stored fluid. The model is applicable to the storage of both hot and chilled water. The model is validated with experimental data from the literature. The parameters that influence the operation of a stratified thermal energy storage for both heat and cool storage are examined. © 1998 John Wiley & Sons, Ltd.     

CD137 agonist potentiates the abscopal efficacy of nanoparticle-based photothermal therapy for melanoma

Despite the promise of immunotherapy such as the immune checkpoint inhibitors(ICIs)anti-PD-1 and anti-CTLA-4 for advanced melanoma,only 26％-52％of patients respo...     

Polymer supported reagents. III. Kinetic study of synthesizing n‐octylacetate using insoluble titanium tetrachloride

Insoluble poly(4‐vinylpyridine‐co‐styrene) beads are prepared using divinylbenzene as the crosslinking agent. These polymer beads are converted into poly(4‐vinylpyridine‐N‐oxide) (PVPNO) under peracetic acid conditions. The resulting polymer is functionalized with titanium tetrachloride (TiCl₄) to afford the corresponding PVPNO‐TiCl₄ complex. This complex shows good catalytic activity for esterification reactions. The kinetics of formation of n‐octylacetate from acetic acid and n‐octanol is reported. The effects of stirring speed, reactant concentration, catalyst amount, percent crosslinking, particle size, and temperature on the conversion is investigated. The rate constants are found to increase with an increase in the stirring speed, concentration of n‐octanol, catalyst amount, and temperature and decrease with an increasing percentage of crosslinking and the mesh size of the polymer beads. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2075–2080, 2000     

Blends of polycarbonate with unmodified and maleic anhydride grafted ABS: fracture mechanics

Physical blends of polycarbonate (PC) and acrylonitrile-butadiene-styrene terpolymer (ABS) at two different weight fractions were made (PC35/ABS65 and P75/ABS25). Reactive blended similar compositions of PC with maleic anhydride grafted ABS (MABS) were also made at the same compositions. The crack resistance behaviour of these two types of blends and feedstocks (PC and ABS) were studied. The generalized locus method was used to investigate the invariance of crack resistance from any set of characteristic points. PC and PC/ABS blends failed immediately after crack initiation. The modified blends (PC/MABS) exhibited failure through crack propagation after crack initiation started. The resistance to crack initiation is determined in terms of critical J-integral value (J_c). The resistance to crack propagation at maximum load point is also determined from the locus of maximum load point on the load-displacement curves. The resistance to steady state crack growth (R_p) during extensive crack propagation is determined from the total essential energy for a complete fracture. The crack resistance values for modified blends are much high compared to unmodified blends and even feedstocks.     

Silicon-on-Insulator-Based Planar Circuit for Passive Optical Network Applications

A novel design of a silicon-on-insulator (SOI) filter for passive optical network applications is described. The SOI filter comprises a monolithically integrated planar reflective grating and a multistage Mach-Zehnder interferometer. The fabricated device showed low insertion losses and high optical isolation. To the best of our knowledge, this letter describes the first demonstration of an SOI circuit comprising monolithically integrated planar reflective grating and cascaded Mach-Zehnder interferometer     

Melanin nano-pigments for heavy metal remediation from water

Melanins are water insoluble polyphenol compounds. The metal ion chelating property of natural melanin is exploited for removal of heavy metals from contaminated water. We optimized biosynthesis of melanin from marine bacterium using different growth media, media components, and operating conditions. Optimized medium yielded 513 mg/L melanin at 36 h of incubation, which was 3.15 times higher than the yield before optimization. Particle size analysis of the biosynthesized melanin indicated a size of 32 ± 0.98 nm. Preliminary investigation indicated that melanin nanoparticles could adsorb different heavy metals such as chromium, selenium, and lead from very low initial concentrations.     

CNN Approaches for Classification of Indian Leaf Species Using Smartphones

Leaf species identification leads to multitude of societal applications. There is enormous research in the lines of plant identification using pattern recognition. With the help of robust algorithms for leaf identification, rural medicine has the potential to reappear as like the previous decades. This paper discusses CNN based approaches for Indian leaf species identification from white background using smartphones. Variations of CNN models over the features like traditional shape, texture, color and venation apart from the other miniature features of uniformity of edge patterns, leaf tip, margin and other statistical features are explored for efficient leaf classification.     

Secure Information Access Strategy for a Virtual Data Centre

With the arrival of on-demand computing, data centre requirements are extensive, with fluid boundaries. Loaded Internet applications, service-orientedarchitectures, virtualization and security provisioning are the major operations of a data centre. Security is an absolute necessity of any network architecture,and the virtual IT data centre is no exception. At the boundary, security is focused on securing the terminals of the data centre from external threats andproviding a secure gateway to the Internet. The paradigm shift towards a new computing environment makes communications more complicated forInfrastructure Providers (InP). This complexity includes the security of the data centre’s components to protect data from malicious attacks or from beingcompromised. Threats/attacks are inevitable if the data are generated from a public network, such as Wi-Fi in an Airport, Railway station and other publicplaces. Since these places create enormous amounts of data from anonymous and naive users, it is essential to store the information in a data centre. In thisarticle, we propose an efficient, secure, and privacy-preservation information access algorithm to access data centres in public wifi networks. This algorithmis based on the primitive root approach for sending and receiving credentials through the anonymous authentication of the users and ensuring protecteddata access from the data centre. Security and Performance Analysis and its evaluation prove that our approach is successful with respect to security, privacypreservation and computational complexity.