Clearance of the SARS-CoV-2 Virus in an Immunocompromised Patient Mediated by Convalescent Plasma without B-Cell Recovery

Coronavirus disease (COVID-19) is a contagious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This case report presents a patient who had difficulty eradicating the corona virus due to being treated with Rituximab, which depletes B lymphocyte cells and therefore disables the production of neutralizing antibodies. The combined use of external anti-viral agents like convalescent plasma, IVIG and Remdesivir successfully helped the patient’s immune system to eradicate the virus without B-cell population recovery. In vitro studies showed that convalescent plasma is the main agent that helped in eradicating the virus.     

Synthesis and optimization of high surface area mesoporous date palm fiber-based nanostructured powder activated carbon for aluminum removal

Date palm fiber (DPF) derived from agrowaste was utilized as a new precursor for the optimized synthesis of a cost-effective, nanostructured, powder-activated carbon (nPAC) for aluminum (Al3+) removal from aqueous solutions using carbonization, KOH activation, response surface methodology (RSM) and central composite design (CCD). The optimum synthesis condition, activation temperature, time and impregna-tion ratio were found to be 650 ℃, 1.09 hour and 1:1, respectively. Furthermore, the optimum conditions for removal were 99.5％and 9.958 mg·g-1 in regard to uptake capacity. The optimum conditions of nPAC was analyzed and characterized using XRD, FTIR, FESEM, BET, TGA and Zeta potential. Moreover, the adsorption of the Al3+ conditions was optimized with an integrated RSM-CCD experimental design. Regression results revealed that the adsorption kinetics data was well fitted by the pseudo-second order model, whereas the adsorption isotherm data was best represented by the Freundlich isotherm model. Optimum activated carbon indicated that DPF can serve as a cost-effective precursor adsorbent for Al3+removal.     

Recent Advances in Poly (Amide-B-Ethylene) Based Membranes for Carbon Dioxide (CO2) Capture: A Review

Polyamide-b-ethylene (Pebax) is a promising material for membrane-based gas separation application with excellent CO₂ capturing potential. Pebax is a rubbery elastomer which offers good mechanical support with its hard crystalline phase and excellent gas transport through its amorphous polyether phase. This review article includes recent advances in Pebax based membrane synthesis, solvent selection for membrane synthesis, compatible fillers with Pebax matrix and the improved gas separation performance of the prepared membranes. The literature review shows that Pebax based membranes are a good candidate for separation of CO₂ from flue gases and can be used for commercial applications.     

Graphene oxide reinforced polyvinyl alcohol/polyethylene glycol blend composites as high-performance dielectric material

Novel flexible dielectric composites composed of polyvinyl alcohol (PVA), polyethylene glycol (PEG), and graphene oxide (GO) with high dielectric constant and low dielectric loss have been developed using facile and eco-friendly colloidal processing technique. The structure and morphology of the PVA/PEG/GO composites were evaluated using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-vis spectroscopy (UV-vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The dielectric behavior of PVA/PEG/GO composites was investigated in the wide range of frequencies from 50 Hz to 20 MHz and temperature in the range 40 to 150 °C using impedance spectroscopy. The dielectric constant for PVA and PVA/PEG (50/50) blend film was found to be 10.71 (50 Hz, 150 °C) and 31.22 (50 Hz, 150 °C), respectively. The dielectric constant for PVA/PEG/GO composite with 3 wt% GO was found to be 644.39 (50 Hz, 150 °C) which is 60 times greater than the dielectric constant of PVA and 20 times greater than the dielectric constant of PVA/PEG (50/50) blend film. The PVA/PEG/GO composites not only show high dielectric constant but also show low dielectric loss which is highly attractive for practical applications. These findings underline the possibilities of using PVA/PEG/GO composites as a flexible dielectric material for high-performance energy storage applications such as embedded capacitors.     

Electrically conducting thin films obtained by ion implantation in pyrolyzed polyacrylonitrile

Heat treatment of polyacrylonitrile (PAN) leads to products with semiconductor-to-metal range of conductivities. The electrical properties of these materials are further modified by ion implantation. The conductivity, 1×10^–7 (Ω cm)^–1, of heat treated PAN at 435°C (PAN435) increases upon ion implantation with As⁺, Kr⁺, Cl⁺ or F⁺, reaching the maximum value of 8.9×10^–1 (Ω cm)^–1 at a dose of 5×10¹⁶ ion/cm² and an energy of 200 KeV for the case of F⁺ implantation. On the other hand, ion implantation in the more conducting heat-treated PAN at 750 °C (PAN750) leads to a decrease in the electrical conductivity. It is shown that the conductivity modifications are primarily due to structural rearrangements induced by the energetic ions. Specific chemical doping contribution to conductivity is noted for halogen implantation in PAN435. The temperature dependence of conductivity of PAN heat treated at 750°C suggests a two path conduction, namely a three dimensional variable range hopping conduction and a metallic conduction. After ion implantation, the conductivity-temperature dependence is interpreted in terms of a variable range hopping conduction mechanism. Received: 25 August 2000 / Reviewed and accepted: 28 August 2000     

Selection of Methodology for Neural Network Modeling of Constitutive Hystereses Behavior of Soils

Classic constitutive modeling of geomaterials based on the elasticity and plasticity theories suffers from limitations pertaining to formulation complexity, idealization of behavior, and excessive empirical parameters. This article capitalizes on the modeling capabilities of neural networks as substitutes for the classic approaches. The neural network–based modeling overcomes the difficulties encountered in understanding the underlying microscopic processes governing the material's behavior by redirecting the efforts into learning the cause-effect relations from behavioral examples. Several methodologies are presented and cross-compared for effectiveness in approximating a theoretical hysteresis model resembling stress-strain behavior. The most effective methodology was used in modeling the constitutive behavior of an experimentally tested soil and produced models that simulated the real behavior of the soil with high accuracy. Although these models are empirical, they are retrainable and thus, unlike classic constitutive modeling techniques, can be revised and generalized easily when new data become available.     

The influence of reusing ‘Formtex’ controlled permeability formwork on strength and durability of concrete

The effects of the reuse of ‘Formtex’ Controlled Permeability Formwork (CPF) liner on strength and durability properties of concrete were investigated at two different water-cement ratios and the results are reported in this paper. Test blocks were cast using the CPF on one side and impermeable formwork (IF) on the opposite side of the mould so that direct comparisons could be made between the two. The strength was assessed using the Limpet pull-off tester and both the air permeability and the water absorption (sorptivity) were measured using the Autoclam Permeability System. Both these instruments measured the ‘covercrete’ properties. In addition, cores cut from the test specimens were subjected to an accelerated carbonation test and a chloride exposure test. The results showed that the ‘Formtex’ CPF increases the surface strength and the durability of concrete compared to the IF. There was an almost complete elimination of blowholes. The permeability of concrete decreased and its resistance to the ingress of both carbon dioxide and chlorides increased when CPF was used. The beneficial effects of the Formtex CPF were most evident in concrete of higher water-cement ratio. With the reuse of the Formtex liner twice, that is a total of three uses, the performance of the CPF to improve the properties of concrete remained almost the same. In this research the CPF liner was cleaned thoroughly between each use, which must be adhered to for site applications for reproducing the beneficial effects observed in the laboratory.     

An Investigation of Branch and Bound Methods for Solving the Segregated Storage Problem

The segregated storage problem consists of determining a minimum cost distribution of products among compartments such that only one product may be stored in a given compartment. This paper explores the computational aspects of using branch and bound methods to solve this problem. Such methods were first suggested for this problem by White and Francis. A variety of approaches are tested, utilizing heuristic node selection and branching decision rules. Three heuristics are also presented which generate solutions for use as initial upper bounds for improving efficiency of the branch and bound procedure or as solutions for very large problems.     

Solar cells sensitised by push–pull azo dyes: dependence of photovoltaic performance on electronic structure,geometry and conformation of the sensitizer

Novel Azo dyes possessing varying conjugation lengths and different extents of electron cloud delocalisation were synthesised and characterised and explored as sensitizers for dye-sensitised solar cells (DSSC). The envisaged azo dyes comprising of electron withdrawing and electron-donating moieties which are linked through conjugation bridges of varying lengths facilitated the prevalence of push–pull mechanism in the molecules. Optimisation of the geometry were performed for the synthesised compounds using B3LYP/ 6-31?+?G (d,p) level of density functional theory and their computed optical absorption and band gaps were validated with experimental results. The dyes exhibited molar extinction coefficients in the range of 3.2?×?10⁴ to 4.2?×?10⁴?mol^?1?Lcm^?1. The highest occupied molecular orbital (HOMO) was located between ?5.53 and ?5.03?eV for the various sensitizers synthesised and their lowest unoccupied molecular orbital (LUMO) was located between ?2.86 and ?3.08?eV. HOMO–LUMO gaps were in the range of 2.02–2.67?eV. Fill factor of the cells varied from 28% to 32% and the power conversion efficiencies ranged from 0.4% to 2.7%. This is the first time reporting of a systematic investigation, correlating the influence of nature and position of substituent, extending of conjugation and geometry of sensitizers on the photo physical properties of the sensitizers and the photovoltaic performance of corresponding DSSC.

Highlights

• The article focuses on push–pull azo dyes and were explored as promising candidate sensitizers for low cost dye-sensitised solar cells (DSSC).

• The effect of chemical structure, extend of conjugation and geometry of the sensitizer on the photo physical properties of the sensitizers and the photovoltaic performance of DSSC were analysed.

     

Magnetic, optical and structural studies on Ag doped ZnO nanoparticles

The influences of annealing effects have been explored on the crystallinity, morphology, optical and magnetic properties of Ag–ZnO nanostructures prepared by a simple sol–gel method. X-ray powder diffraction, scanning electron microscope, high resolution transmission electron microscope (HRTEM), vibrating sample magnetometer and photoluminescence spectroscopy (PL) have been used to characterize the crystal structures, surface morphology, magnetic and optical properties of the pure ZnO and Ag–ZnO nanostructures respectively. The synthesized Ag–ZnO nanostructures are found to have hexagonal wurtzite crystal structures and their grain size increases while lattice strain decreases on annealing. From HRTEM observation, it is found that the annealed samples show nanorod like structures with Ag nanoparticles (NPs) embedded on the surface. Due to annealing effect, Ag–ZnO shows higher saturation magnetization at room temperature.