A Characterization of Vacuum

In this note, we use a Killing vector field on a 4-dimensional Lorentzian space-time (M,g), to obtain sufficient conditions for (M,g) to be a vacuum.     

Electrokinetic properties of bare and particles containing textile

Functional, reactive and smart textiles are nowadays of great interest in the fields of both cosmetic and pharmaceutical industries. Textile functionalization according to demands of the consumers can only be achieved with better understanding of the properties of the textile surface as well as sound knowledge about the technique to be used to functionalize the textiles. The aim of this work was to investigate the zeta potential of polyamide textile and prepared sponge like particles as a function of pH and salinity of the electrolyte. Special attention has been dedicated to the electrokinetic properties of textile as a function of sponge like particles amount present during adsorption process. As a general tendency, streaming potential measurement showed the changes in surface charge density of textile because of the changes in pH, salinity and adsorbed particles amount. All presented results were discussed in terms of zeta potential. Copyright © 2016 John Wiley & Sons, Ltd.     

Beneficiation of zinc from electric arc furnace dust using hydrometallurgical approach

Zinc bearing wastes such as electric arc furnace dust (EAFD) obtained from steel making constitute an important resource for zinc extraction. Inclusion of heavy metals such as Pb, Cd, Cu, Cr, Ni, etc., in these wastes makes them hazardous to use and/or dispose. In the present research work, leaching kinetics of EAFD with sulfuric acid has been investigated and various experimental parameters such as concentration of lixiviant, stirring rate, sample particle size, liquid/solid proportion, and temperature of the reaction have been optimized. It has been found that the dissolution rate of EAFD increases with rise in temperature, acidic strength, rate of stirring, liquid to solid proportion and with reduction in EAFD particle size. From the analysis of leaching kinetic data by means of graphical and statistical methods, it has been evaluated that the leaching kinetics of EAFD is dictated by surface diffusion reaction. Apparent energy of activation for the leaching reaction of EAFD with sulfuric acid is found to be 13.1 kJ mol^–1 within the temperature range of 308 to 358 K.     

Poly Lactic Acid (PLA) Nanocomposites: Effect of Inorganic Nanoparticles Reinforcement on Its Performance and Food Packaging Applications

Poly lactic acid (PLA) is a compostable, as well as recyclable, sustainable, versatile and environmentally friendly alternative, because the monomer of PLA-lactide (LA) is extracted from natural sources. PLA’s techno-functional properties are fairly similar to fossil-based polymers; however, in pristine state, its brittleness and delicacy during processing pose challenges to its potential exploitation in diverse food packaging applications. PLA is, therefore, re-engineered to improve its thermal, rheological, barrier and mechanical properties through nanoparticle (NP) reinforcement. This review summarises the studies on PLA-based nanocomposites (PLA NCs) developed by reinforcing inorganic metal/metallic oxide, graphite and silica-based nanoparticles (NPs) that exhibit remarkable improvement in terms of storage modulus, tensile strength, crystallinity, glass transition temperature (Tg) value, antimicrobial property and a decrease in water vapour and oxygen permeability when compared with the pristine PLA films. This review has also discussed the regulations around the use of metal oxide-based NPs in food packaging, PLA NC biodegradability and their applications in food systems. The industrial acceptance of NCs shows highly promising perspectives for the replacement of traditional petrochemical-based polymers currently being used for food packaging.     

On the formation of spin dependent double layer structure in astrophysical plasmas

Double layers (DLs) are nonlinear structures, and are thought to be responsible for particle acceleration in laboratory plasmas and astrophysical plasmas. In this paper, the existence of spin dependent DLs structure is explored using separate spin evolution quantum hydrodynamic model. Based on reductive perturbation method, we derived an extended Korteweg–de Vries (eKdV) equation to demonstrate the existence and nature of DLs. We found that spin polarization significantly enhanced the amplitude of the electrostatic potential associated with DLs. Further, spin polarization also increases the depth and width of the Sagdeev potential. It is noted that the contribution of Bohm potential effect is essential for the formation of DLs structure. Our results may be helpful to explain the phenomenon of particle acceleration in dense astrophysical environments specifically in a white dwarf.     

Random matrix model for disordered conductors

We present a random matrix ensemble where real, positive semi-definite matrix elements, x, are log-normal distributed, exp[−log²(x)]. We show that the level density varies with energy, E, as 2/(1+E) for large E, in the unitary family, consistent with the expectation for disordered conductors. The two-level correlation function is studied for the unitary family and found to be largely of the universal form despite the fact that the level density has a non-compact support. The results are based on the method of orthogonal polynomials (the Stieltjes-Wigert polynomials here). An interesting random walk problem associated with the joint probability distribution of the ensuing ensemble is discussed and its connection with level dynamics is brought out. It is further proved that Dyson’s Coulomb gas analogy breaks down whenever the confining potential is given by a transcendental function for which there exist orthogonal polynomials.     

ZnO Nanoparticles of Rubia cordifolia Extract Formulation Developed and Optimized with QbD Application,Considering Ex Vivo Skin Permeation,Antimicrobial and Antioxidant Properties

The objective of the current research is to develop ZnO-Manjistha extract (ZnO-MJE) nanoparticles (NPs) and to investigate their transdermal delivery as well as antimicrobial and antioxidant activity. The optimized formulation was further evaluated based on different parameters. The ZnO-MJE-NPs were prepared by mixing 10 mM ZnSO₄·7H₂O and 0.8% w/v NaOH in distilled water. To the above, a solution of 10 mL MJE (10 mg) in 50 mL of zinc sulfate was added. Box–Behnken design (Design-Expert software 12.0.1.0) was used for the optimization of ZnO-MJE-NP formulations. The ZnO-MJE-NPs were evaluated for their physicochemical characterization, in vitro release activity, ex vivo permeation across rat skin, antimicrobial activity using sterilized agar media, and antioxidant activity by the DPPH free radical method. The optimized ZnO-MJE-NP formulation (F13) showed a particle size of 257.1 ± 0.76 nm, PDI value of 0.289 ± 0.003, and entrapment efficiency of 79 ± 0.33%. Drug release kinetic models showed that the formulation followed the Korsmeyer–Peppas model with a drug release of 34.50 ± 2.56 at pH 7.4 in 24 h. In ex vivo studies ZnO-MJE-NPs-opt permeation was 63.26%. The antibacterial activity was found to be enhanced in ZnO-MJE-NPs-opt and antioxidant activity was found to be highest (93.14 ± 4.05%) at 100 µg/mL concentrations. The ZnO-MJE-NPs-opt formulation showed prolonged release of the MJE and intensified permeation. Moreover, the formulation was found to show significantly (p < 0.05) better antimicrobial and antioxidant activity as compared to conventional suspension formulations.     

MEH-PPV/Alq_3-based bulk heterojunction photodetector

In this paper, we present the effect of varied illumination levels on the electrical properties of the organic blend bulk heterojuction （BHJ） photodiode. To prepare the BHJ blend, poly（2-methoxy-5（2P-ethylhexyloxy） phenyleneviny- lene （MEH-PPV） and aluminum-tris-（8-hydroxyquinoline） （Alq3） are used as donor and acceptor materials, respectively. In order to fabricate the photodiode, a 40-nm thick film of poly（3, 4-ethylendioxytbiophene）：poly（styrensulfonate） （PE- DOT：PSS） is primarily deposited on a cleaned ITO coated glass substrate by spin coating technique. The organic photo- sensitive blend is later spun coated on the PEDOT：PSS layer, followed by the lithium fluoride （LiF） and aluminium （A1） thin films deposition by thermal evaporation. The optical properties of the MEH-PPV：Alq3 blend thin films are investigated using photoluminescence （PL） and UV-Vis spectroscopy. The photodiode shows good photo-current response as a function of variable illumination levels. The responsivity value - 8 mA/W at 3 V is found and the ratio of photo-current to dark current （lph/IDark） is found to be 1.24.