Influence of clay modification on the properties of aramid-layered silicate nanocomposites

Nanocomposites from organoclay and aromatic polyamide were prepared using solution intercalation method. Aramid chains were synthesised by reacting 4-aminophenylsulfone with isophthaloyl chloride in dimethylacetamide. Dodecylamine was used as a modifier to change the hydrophilic nature of montmorillonite into organophilic. Suitable quantities of organoclay were mixed in the aramid solution with high-speed stirring for homogeneous dispersion of the clay. Thin films cast from these materials after evaporating the solvent were characterised. The morphology of nanocomposites was determined by X-ray diffraction and TEM. Results revealed the formation of delaminated and disordered intercalated clay platelets in the aramid matrix. Mechanical data indicated improvement in the tensile strength and modulus with clay loading up to 6 wt.%. The glass transition temperature increased up to 20 wt.% organoclay, suggesting better cohesion between the two phases and thermal stability augmented with increasing clay loading. The water uptake reduced gradually as a function of organoclay showing decreased permeability.     

Optically Controlled Construction of Three-Dimensional Protein Arrays

Protein crystallization is an important tool for structural biology and nanostructure preparation. Here, we report on kinetic pathway-dependent protein crystals that are controlled by light. Photo-responsive crystallites are obtained by complexing the model proteins with cationic azobenzene dyes. The crystalline state is readily switched to a dispersed phase under ultraviolet light and restored by subsequent visible-light illumination. The switching can be reversibly repeated for multiple cycles without noticeable structure deterioration. Importantly, the photo-treatment not only significantly increases the crystallinity, but creates crystallites at conditions where no ordered lattices are observed upon directly mixing the components. Further control over the azobenzene isomerization kinetics produces protein single crystals of up to ≈50 μm. This approach offers an intriguing method to fabricate metamaterials and study optically controlled crystallization.     

Time–aging time–stress superposition in soft glass under tensile deformation field

We have studied the tensile deformation behaviour of thin films of aging aqueous suspension of Laponite, a model soft glassy material, when subjected to a creep flow field generated by a constant engineering normal stress. Aqueous suspension of Laponite demonstrates aging behaviour wherein it undergoes time-dependent enhancement of its elastic modulus as well as its characteristic relaxation time. However, under application of the normal stress, the rate of aging decreases and in the limit of high stress, the aging stops with the suspension now undergoing a plastic deformation. Overall, it is observed that the aging that occurs over short creep times at small normal stresses is the same as the aging that occurs over long creep times at large normal stresses. This observation allows us to suggest an aging time–process time–normal stress superposition principle, which can predict rheological behaviour at longer times by carrying out short time tests.     

Telluride-Based Materials: A Promising Route for High Performance Supercapacitors

As supercapacitor (SC) technology continues to evolve, there is a growing need for electrode materials with high energy/power densities and cycling stability. However, research and development of electrode materials with such characteristics is essential for commercialization the SC. To meet this demand, the development of superior electrode materials has become an increasingly critical step. The electrochemical performance of SCs is greatly influenced by various factors such as the reaction mechanism, crystal structure, and kinetics of electron/ion transfer in the electrodes, which have been challenging to address using previously investigated electrode materials like carbon and metal oxides/sulfides. Recently, tellurium and telluride-based materials have garnered increasing interest in energy storage technology owing to their high electronic conductivity, favorable crystal structure, and excellent volumetric capacity. This review provides a comprehensive understanding of the fundamental properties and energy storage performance of tellurium- and Te-based materials by introducing their physicochemical properties. First, we elaborate on the significance of tellurides. Next, the charge storage mechanism of functional telluride materials and important synthesis strategies are summarized. Then, research advancements in metal and carbon-based telluride materials, as well as the effectiveness of tellurides for SCs, were analyzed by emphasizing their essential properties and extensive advantages. Finally, the remaining challenges and prospects for improving the telluride-based supercapacitive performance are outlined.     

Analysis of Soil by Magnetic Field Assisted Calibration-Free Laser Induced Breakdown Spectroscopy (CF-LIBS) and Laser Ablation – Time-of-Flight Mass Spectrometry (LA-TOF-MS)

The qualitative and quantitative analysis of soil samples collected from Sialkot, Pakistan (which contains leather industrial plants), has been performed using laser-induced breakdown spectroscopy (LIBS) and laser ablation time of flight mass spectrometry (LA-TOF-MS). The focused beam of a Q-switched Nd: YAG laser (532?nm) was used to ablate the soil samples in air at atmospheric pressure. The optical emission spectra demonstrate the presence of the spectral lines of Si, Fe, Al, Ca, Ti, K, Cr, Mg, Na, Ba, and Li in all of the samples. The emission lines intensities, electron number densities, and excitation temperatures were significantly enhanced in the presence of an external 0.3 T magnetic field applied perpendicular to the plasma plume. A maximum enhancement factor of approximately 8 was observed in the emission intensity. The emergence of several additional lines has also been detected using the magnetic field-assisted LIBS approach. The elemental composition determined using calibration-free laser-induced breakdown spectroscopy (CF-LIBS), with and without magnetic field, reveals that the external magnetic field only adjusts the laser-generated plasma dynamics without affecting the quantitative analysis of the samples. Importantly, the toxic and heavy elements such as chromium and barium were detected and quantified in all of the soil samples by both of these techniques. The variations in the compositional analysis using CF-LIBS with and without the applied magnetic field and LA-TOF-MS were less than 10%.     

A Privacy Scheme for Digital Images Based on Quantum Particles

International Journal of Theoretical Physics - Quantum processing inspired every field of science and technology. Quantum digital content privacy schemes usually employs photons to communicate a...     

A novel construction of substitution box using a combination of chaotic maps with improved chaotic range

The influential application of substitution boxes in secure communication and multimedia security attracted researchers to construct more robust substitution boxes. The advantage of using chaos in the secure communication is to get additional unpredictability and randomness in data. In this paper, substitution boxes are constructed with the help of chaotic system and linear fractional transformation. The 256 distinct values of each substitution box are then checked with the help of different available algebraic and statistical analyses. These tests evaluate the strength and application of substitution boxes in different encryption techniques. The results indicate the strength of anticipated technique.

     

Supramolecular homobimetallic <Emphasis Type="Italic">bis</Emphasis>-diorganotin(IV) complexes of ditopic oxygen nitrogen donor ligand: synthesis,spectroscopic characterization,crystal structure and biological screening

Six new homobimetallic bis-diorganotin(IV) complexes: [Me₂Sn]₂L (1), [Et₂Sn]₂L (2), [n-Bu₂Sn]₂L (3), [Ph₂Sn]₂L (4), [Oct₂Sn]₂L (5) and [n-BuClSn]₂L (6) (H ₄ L=N¹′, N⁶′-bis(2-hydroxybenzylidene)adipodihydrazide) have been synthesized and structurally characterized by means of elemental analysis, mass spectroscopy, FT-IR, NMR (¹H, ¹³C{¹H}, ¹¹⁹Sn) and single-crystal X-ray diffraction. Spectroscopic studies indicate coordination of the ligand to the diorganotin(IV) moieties via iminolic oxygen, nitrogen and phenolic oxygen atoms generating pentacoordinated tin centers. Single-crystal X-ray analysis of (1) revealed homobimetallic nature of complex with dimethyltin moieties oriented in trans-conformation. The ligand is non-planar with each Sn atom in a distorted square pyramidal coordination geometry. Packing diagrams suggest the essential role of C–H^…N and C–H^…O interactions in generating supramolecular assembly. The ligand and complexes were screened for in vitro antimicrobial activity and cytotoxicity. Compound (4) exhibits highest cytotoxicity.     

Finite-element analysis of rectangular plates with rectangular inserts

The present investigation deals with the stress distribution in the vicinity of rectangular inserts in finite rectangular plates. This problem is more complex due to the singularities at the corners of the inserts. In this paper, the finite-element technique is used to determine the deformations and, subsequently, the stresses. The paper treats the problem in a generalized form in the sense that the size and orientation of the insert are taken as variables. The finite rectangular plate is subjected to a uniform axial tensile load. The material of the plate and that of the insert are considered to be different. Element selections are made which are optimal with regard to accuracy and computational effort. The local element stresses which generate considerable discontinuity at the element nodes are plotted. Averaging process for the local stress calculations is discussed and these are compared with the results available¹ which are obtained by experimental techniques.