The SARS-CoV-2 causes severe pulmonary infectious disease with an exponential spread-ability. In the present research, we have tried to look into the molecular cause of disease, dealing with the development and spread of the coronavirus disease 2019 (COVID-19). Therefore, different approaches have investigated against disease development and infection in this research; First, We identified hsa-miR-1307-3p out of 1872 pooled microRNAs, as the best miRNA, with the highest affinity to SARS-CoV-2 genome and its related cell signaling pathways. Second, the findings presented that this miRNA had a considerable role in PI3K/Act, endocytosis, and type 2 diabetes, moreover, it may play a critical role in the prevention of GRP78 production and the virus entering, proliferation and development. Third, nearly 1033 medicinal herbal compounds were collected and docked with ACE2, TMPRSS2, GRP78, and AT1R receptors, which were the most noticeable receptors in causing the COVID-19. Among them, there were three common compounds including berbamine, hypericin, and hesperidin, which were more effective and appropriate to prevent the COVID-19 infection. Also, it was revealed some of these chemical compounds which had a greater affinity for AT1R receptor inhibitors can be suitable therapeutic targets for inhibiting AT1R and preventing the adverse side effects of this receptor. According to the result, clinical assessment of these three herbal compounds and hsa-miR-1307-3p may have significant outcomes for the prevention, control, and treatment of COVID-19 infection.

MicroRNAs (miRNAs, miRs) are small (21-25 nucleotides) endogenous and noncoding RNAs involved in many cellular processes such as apoptosis, development, proliferation, and differentiation via binding to the 3'-untranslated region of the target mRNA and inhibiting its translation. Angiogenesis is a hallmark of cancer, which provides oxygen and nutrition for tumor growth while removing deposits and wastes from the tumor microenvironment. There are many angiogenesis stimulators, among which vascular endothelial growth factor (VEGF) is the most well known. VEGF has three tyrosine kinase receptors, which, following VEGF binding, initiate proliferation, invasion, migration, and angiogenesis of endothelial cells in the tumor environment. One of the tumor microenvironment conditions that induce angiogenesis through increasing VEGF and its receptors expression is hypoxia. Several miRNAs have been identified that affect different targets in the tumor angiogenesis pathway. Most of these miRNAs affect VEGF and its tyrosine kinase receptors expression downstream of the hypoxia-inducible Factor 1 (HIF-1). This review focuses on tumor angiogenesis regulation by miRNAs and the mechanism underlying this regulation.

To molecularly investigate the role of the microstructure in controlling the dynamics of segmented polyurethanes (PUs), a series of them were systematically designed, synthesized, and experimentally scrutinized. Broadband dielectric spectroscopy and rheometry along with small-angle X-ray scattering and differential scanning calorimetry were applied to provide insights into molecular origins, particularly the role of transitional friction coefficients (ζ), affecting dynamics and rheology of the various microstructures of PUs. In this way, first, the effective ζs of model PUs were extracted from their rheological data using the Bueche−Ferry procedure. Second, the experienced ζ by the hard and soft segments (SS and HS) in pure components and resultant PUs were calculated using BDS data and were applied in a Rouse model based methodology to estimate the effective ζ. Finally, the obtained effective ζ from rheometry (ζ eff ) and BDS (ζ eff Rouse ) were compared at the same temperatures. For highly microphase-mixed system with liquid-like terminal behavior, ζ eff Rouse was consistent with ζ eff . For microphase-separated PUs with their nonterminal behavior, however, a fairly large difference between ζ eff and ζ eff Rouse was found. A universal curve was also prepared to illustrate the relationship between the dynamics and microstructural features of model PUs. According to these results and the SAXS data analyses, the frictional forces acting at the interfaces between SS-rich and HS-rich phases were suggested as a main origin for the deviation from terminal Rouse-like dynamics in the microphase-separated PUs, while bare friction coefficients in their pure components play an insignificant role in the dynamics of these systems.

Uniform latexes of anionically polymerized polystyrene, Mn = 180 000, Mn = 250 000, and M" = 420 000, were prepared by direct miniemulsification. The 1200-A-diameter particles were cleaned, dried, and sintered, and the resulting films were annealed for various periods of time at 144 °C. The films were fractured with fine dental burr instrumentation at a depth of 4000 A/pass. The number of chain ruptures and consumed energy per unit area were measured, as well as tensile strength. Plots of chain scissions and energy consumed vs 0.5 power of annealing time showed three regimes: mixed, peak, and recovery. Data in the mixed regime confirm portions of the de Gennes and Tirrell theory which predicts a 0.5 power dependence on annealing time and portions of the Wool theory. Using the Lake-Thomas theory, rubber elasticity theory, and bond dissociation energy, the contribution of the several mechanisms consuming energy were estimated on the basis of an energy balance approach. A mechanism involving the scissor-action opening of the 109s carbon-carbon bond and concomitant bond stretching of the about 300 bonds trapped between entanglements is consistent with the consumption of most of the energy in the later annealing stages and/or fast fracture processes. Tensile strength and the fracture energy per unit area of the films increase linearly with the number of chain scissions per unit fracture area in the first regime, as predicted by Peppas.

BACKGROUND: In the electrospinning process, through subjecting a pendent drop of a polymer solution to a high electric field, a fluid jet is ejected from the drop. To have a stable process, the rate at which the fluid is forced into the drop and the rate at which the fluid is carried away by the jet must be equal. A method is reported to find the point at which the flow into the drop is equal to the flow out of the drop.RESULTS: In the electrospinning of polyacrylonitrile solutions, by applying different voltages at a constant solution feed rate, two jet regimes were observed: stable jet and fluctuating jet regimes. The stable jet regime occurred at low voltages where the jet flow rate was lower than the feed rate, and the fluctuating jet regime occurred at higher voltages where the jet flow rate exceeded the feed rate. The highest voltage in the stable jet regime was the point where the jet flow rate was equal to the feed rate. This point was determined for different feed rates.CONCLUSION: By applying various voltages at different feed rates, and investigating the jet current, a curve showing stable processing points can be obtained. Copyright © 2008 Society of Chemical Industry

Temperature-induced nonlinearity of an upper critical solution temperature (UCST) copolymer blend and its nanocomposites containing 5 wt% mono-size soft nanoparticles (SNPs) were investigated. Mechanical and thermal energies contribution into the nonlinearity of UCST copolymer blend was 8.9×10 3 Jm −3 and 2.2×10 3 Jmol −1 , respectively. Addition of SNP did not change the system thermal-based nonlinearity, while altered its mechanical contribution at constant heating and solicitation conditions. It diminished to 0.4× 10 3 Jm −3 in the nanocomposite containing nano-size dispersion of aged SNPs. Micron-size agglomeration of the fresh SNPs in the nanocomposite; however, enhanced the required mechanical energy for nonlinearity to 4.1×10 3 Jm −3 . Shorttime annealing of the nanocomposite with micron-size agglomerates reduced its mechanical energy part to 2.8 × 10 3 Jm −3 , while annealing extension maximized it at 9.3× 10 3 Jm −3 . Heating rate increase amplified the thermal contribution into the nonlinearity at constant or reduced mechanical contribution. Finally, room-temperature annealing magnified the temperature-induced nonlinearity of the UCST copolymer blend at minimum mechanical contribution.

The structure and thermal behavior of poly(lactic acid) (PLA) multifilament yarns were studied by complementary techniques of differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and wide angle X-ray diffraction (WAXD). As for PLA filaments, notable differences in the WAXD patterns, DSC curves, and FTIR spectra were observed. The combination of the WAXD and FTIR results showed that PLA samples with different crystallinity contain a-form crystal structure. The FTIR spectra of the filaments were analyzed to study their crystallinity and crystal structure. The total crystallinity of the PLA filaments was obtained from the percent area loss of the skeletal amorphous band at 955 cm À1. Crystalline fraction from FTIR and DSC were comparable with each other. The C¼ ¼O stretching region, which is sensitive to crystallization and dipole-dipole interactions, was evaluated to provide information about chain conformers and crystallinity of the samples. Depending on the processing conditions, double melting peaks were observed in the DSC curves of the samples. This exhibited the structural reorganization of the crystal phase during heating affected by heating and cooling rate. In the DSC curves of the nearly amorphous multifilament yarn, the exothermic peak observed right above the glass transition temperature (T g ) indicated two relaxed and deformed amorphous regions. However, the multifilament yarn with higher crystallinity showed just endothermic melting peak after its glass transition. V C 2010 Wiley Periodicals, Inc. J Appl

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