Research on the Tensile Properties of Packaging Film Based on Environmental Protection PVA-KGM

Konjac glucomannan (KGM) and poly (vinyl alcohol) (PVA) were mixed to form gel-like polyelectrolyte solution with glycerol and sorbitol as compound plasticizer, which was used to prepare packaging films via casting and drying. The results show that the tensile strength and elongation at break of the packaging films drop sharply when the blending temperature and blending time exceed 80 °C and 3.5 h. When the mass ratio of sorbitol and glycerol in the compound plasticizer ranges from 1:1 to 1:3, it is beneficial to improve the tensile strength of the packaging films. The microscopic reasons for the change of the tensile properties of the packaging films are mainly caused by diffusion-stop-continuing diffusion—precipitation of low-molecular electrolyte, which makes the system shift from equilibrium-homogeneous state- unbalanced state—heterogeneous state.

Polyelectrolyte Multilayered Nanoparticles as Nanocontainers for Enzyme Breakers During Hydraulic Fracturing Process

In this study, Layer-by-Layer (LbL) assembled polyelectrolyte multilayered nanoparticles were developed as a technique for targeted and controlled release of enzyme breakers. Polyelectrolyte multilayers (PEMs) were assembled by means of alternate electrostatic adsorption of polyanions and polycations using colloidal structure of polyelectrolyte complexes (PECs) as LbL building blocks. High enzyme concentrations were introduced into polyethyleneimine (PEI), a positively charged polyelectrolyte solution, to form an electrostatic PECs with dextran sulfate (DS), a negatively charged polyelectrolyte solution. Under the right concentrations and pH conditions, PEMs were assembled by alternating deposition of PEI with DS solutions at the colloidal structure of PEI-DS complexes. Stability and reproducibility of PEMs were tested over time. This work demonstrates the significance of PEMs as a technique for the targeted and controlled release of enzymes based on their high loading capacity, high capsulation efficiency, and extreme control over enzyme concentration. Entrapment efficiency (EE%) of polyelectrolyte multilayered nanoparticles were evaluated using concentration measurement methods as enzyme viscometric assays. Controlled release of enzyme entrapped within PEMs was sustained over longer time periods (> 18 hours) through reduction in viscosity, and elastic modulus of borate-crosslinked hydroxypropyl guar (HPG). Long-term fracture conductivity tests at 40℃ under closure stresses of 1,000, 2,000, and 4,000 psi revealed high fracture clean-up efficiency for fracturing fluid mixed with enzyme-loaded PEMs nanoparticles. The retained fracture conductivity improvement from 25% to 60% indicates the impact of controlled distribution of nanoparticles in the filter cake and along the entire fracture face as opposed to the randomly dispersed unentrapped enzyme. Retained fracture conductivity was found to be 34% for fluid systems containing conventional enzyme-loaded PECs. Additionally, enzyme-loaded PEMs demonstrated enhanced nanoparticle distribution, high loading and entrapment efficiency, and sustained release of the enzyme. This allows for the addition of higher enzyme concentrations without compromising the fluid properties during a treatment, thereby effectively degrading the concentrated residual gel to a greater extent. Fluid loss properties of polyelectrolyte multilayered nanoparticles were also studied under static conditions using a high-pressure fluid loss cell. A borate-crosslinked HPG mixed with nanoparticles was filtered against core plugs with similar permeabilities. The addition of multilayered nanoparticles into the fracturing fluid was observed to significantly improve the fluid- loss prevention effect. The spurt-loss coefficient values were also determined to cause lower filtrate volume than those with crosslinked base solutions. The PEI-DS complex bridging effects revealed a denser, colored filter cake indicating a relatively homogenous dispersion and properly sized particles in the filter cake.

Possibilities of Hyperinflammation Correction in COVID-19

Objective. To evaluate the effect of sodium meglumine succinate on the severity of the systemic inflammatory response syndrome when used in complex therapy in patients with severe COVID-19.Material and Methods. The clinical and laboratory data of 12 patients with the diagnosis «Novel coronavirus infection COVID-19 complicated by community-acquired bilateral polysegmental interstitial pneumonia» were analyzed. All patients underwent intensive therapy with a limited volume of water load in the intensive care unit in accordance with the recommendations of the Ministry of Health of the Russian Federation. Seven patients (observation group) received a polyelectrolyte solution containing meglumine sodium succinate (Reamberin) as part of the therapy at a daily dose of 5 ml/kg during the entire period of stay in the ICU (3–10 days). The control group included 5 patients who received a similar volume of a conventional polyelectrolyte solution containing no metabolically active substrates. The study was pilot in nature due to the small number of patients. The laboratory parameters of arterial and venous blood were measured at the following stages: 1) upon admission to the ICU; 2) 2–4 hours after the completion of Reamberin infusion; 3) 8–12 hours after drug administration; 4) 24 hours after the start of intensive care. Mortality rate and the incidence of thrombotic complications in the groups were assessed on the 28th day of observation. The presence of the therapeutic intervention effect was established using multivariate analysis of variance (MANOVA).Results. A positive effect of the study drug on the severity of systemic inflammatory response syndrome (SIRS) against the background of ongoing etiotropic therapy was noted. Efficiency criteria were the correction of hyperfibrinogenemia, normalization of the platelet count, decrease in the level of C-reactive protein, ferritin, and leukocytosis. A significant decrease in the frequency of thromboembolic events was observed within 28 days of treatment, as well as a reduction in the length of time the patients spent in the ICU.Conclusion. Based on the results of the pilot study, it can be assumed that the antihypoxic and antiradical effects of the drug contribute to the reduction of pulmonary and systemic endotheliitis, which is characteristic of severe forms of the disease and, as a result, inhibits the development of the systemic inflammatory response syndrome. The data obtained can serve as a basis for further in-depth studies.

Diffusion of nanoparticles within a semidilute polyelectrolyte solution

We studied the diffusion of charged gold nanoparticles within a semidilute solution of weakly charged polyelectrolyte, polyacrylic acid (PAA) of high molecular weight (Mw = 106 g mol−1) by using fluorescence correlation spectroscopy (FCS).