Low Molecular Weight Polyethylene Research Articles

THREADED LUBRICANTS FOR DRILL PIPES BASED ON OIL PRODUCTION WASTE

The oil and gas industry occupies a leading position in the development of the country's fuel and energy complex, and the effectiveness of its activities largely depends on the technical and economic indicators of drilling. When performing well work and operating oil and gas wells, many material costs are associated with the operation of oil pipes, namely the reliability of threaded connections operating at high pressures and temperatures in aggressive environments. The need to develop deeper and deeper horizons, the use of forced drilling modes, the transition to later stages of operation of most oil and gas fields, the aging of existing funds and the increase in the volume of overhauls leads to an increase in tripping operations, and therefore the requirements for the reliability of the connection of oil-grade pipes are moving to a new level. Studies have shown that up to 87 % of all drill string accidents are related to poor thread condition. This unsatisfactory condition of the locking threaded joints forces us to look for ways to improve durability. Many foreign and domestic scientists have been studying and improving threaded joints in drill pipes. According to the authors, one of the most promising ways to increase the TEI of drilling is to develop and use more and more effective lubricants for locking joints of drilling tools. Studies have shown that conventional lubricants are not effective enough in modern realities, and sometimes lubricants are completely washed out of threaded joints. In addition, as the drilling depth increases, the friction force increases and the hydrodynamic load increases, and the increase in pressure in the threaded connection complicates the conditions due to the effect on the lubricant of chemically active and abrasive drilling muds and many other factors. The article discusses the obtained results of studies of lubricant bases for threaded connections of drill pipes used for the oil industry, the distinctive features of which are physical and chemical composition, including low molecular weight polyethylene, synthetic rubber, rubber softeners, powdered graphite, vegetable oils.The authors of the article selected the basis of lubricant from industrial rubber production waste, and also presented the advantages of the developed lubricants and materials. The practical significance of the obtained research results lies in the possibility of increasing the wear and sealing properties of threaded pipe joints used in drilling oil and gas wells.

Modification of Properties of Composites Based on Ultrahigh Molecular Weight Polyethylene by Creating Two-Layer Coatings with Low Molecular Weight Polyethylene on Filler Particles: Effect of Composition of Two-Layer Coatings on the Structure and Properties of Composites

Modification of Properties of Composites Based on Ultrahigh Molecular Weight Polyethylene by Creating Two-Layer Coatings with Low Molecular Weight Polyethylene on Filler Particles: Effect of Composition of Two-Layer Coatings on the Structure and Properties of Composites

3D Printed Drug Delivery Systems in Action-Magnetic Resonance Imaging and Relaxometry for Monitoring Mass Transport Phenomena.

The hypothesis of the study was that (1) 3D printed drug delivery systems (DDS) could be characterized in situ during drug release using NMR/MRI techniques in terms of mass transport phenomena description (interfacial phenomena), particularly for systems dealing with two mobile phases (e.g., water and low molecular weight liquid polymer); (2) consequently, it could be possible to deduce how these interfacial mass transport phenomena influence functional properties of 3D printed DDS. Matrix drug delivery systems, prepared using masked stereolithography (MSLA), containing poly(ethylene glycol) diacrylate (PEGDA) and low molecular weight polyethylene glycol (PEG) with ropinirole hydrochloride (RH) were studied as example formulations. The PEGDA to PEG (mobile phase) concentration ratio influenced drug release. It was reflected in spatiotemporal changes in parametric T2 relaxation time (T2) and amplitude (A) images obtained using magnetic resonance imaging (MRI) and T1-T2 relaxation time correlations obtained using low-field time-domain nuclear magnetic resonance (LF TD NMR) relaxometry during incubation in water. For most of the tested formulations, two signal components related to PEG and water were assessed in the hydrated matrices by MRI relaxometry (parametric T2/A images). The PEG component faded out due to outward PEG diffusion and was gradually replaced by the water component. Both components spatially and temporally changed their parameters, reflecting evolving water-polymer interactions. The study shows that dynamic phenomena related to bidirectional mass transport can be quantified in situ using NMR and MRI techniques to gain insight into drug release mechanisms from 3D printed DDS systems.

Pseudomonas aeruginosa Recombinant L-asparaginase: PEGylation with Low Molecular Weight Polyethylene Glycol, Molecular Dynamics Simulation, In vitro and In vivo Serum half-life and Biochemical Characterization.

Microbial L-asparaginase (L-ASNase, EC 3.5.1.1) is a pivotal biopharmaceutical drug-protein that catalyzes the hydrolysis of the non-essential amino acid L-asparagine (L-Asn) into L-aspartic acid (L-Asp) and ammonia , resulting in deplenishing the cellular L-Asn pool, which leads to the ultimate death of the L-asparagine synthetase (L-ASNS) deficient cancerous cells. This study aimed to investigate the impact of conjugating low molecular weight polyethylene glycol to recombinant P. aeruginosa L-ASNase by examining the pharmacokinetic properties, affinity towards the substrate, and enzyme stability prior to and following the reaction. The recombinant P. aeruginosa L-ASNase was affinity purified and then PEGylated by attaching polyethylene glycol (MW= 330 Da) site-specifically to the protein's N-terminus end. After which, the PEGylated L-ASNase was examined by SDS-PAGE (15%), FTIR, and UV/Vis spectrophotometry and subsequently biochemically characterized. The Km and Vmax values of free P. aeruginosa rL-ASNase were determined to be 0.318 ±1.76 mM and 2915 μmol min-1and following the PEGylation, they were found to be 0.396 ±1.736 mM and 3193 μmol min-1, respectively. Polyethylene glycol (330 Da) has markedly enhanced LASNase thermostability at 37, 45, 50, and 55 °C, as opposed to the free enzyme, which retained 19.5% after 1 h of incubation at 37 °C. The PEGylated L-ASNase was found to be stable upon incubation with human serum for 28 h, in contrast to the sharp decline in the residual bioactivity of the free rL-ASNase after 4 h incubation. Accordingly, an in vivo study was used for validation, and it demonstrated that PEGylated rL-ASNase exhibited longer bioactivity for 24 h, while the free form's activity vanished entirely from the rats' blood sera after 8 h. Molecular dynamics simulation indicated that PEG (330 Da) has affected the hydrodynamic volume of L-ASNase and increased its structural stability. Docking analysis has explored the position of PEG with respect to binding sites and predicted a similar binding affinity to that of the free enzyme. For the first time, recombinant L-ASNase was modified by covalently attaching PEG (330 Da). The resultant novel proposed PEGylated rL-ASNase with remarkably increased stability and prolonged in vivo half-life duration, which could be considered an alternative to mitigate the high molecular weight of PEGylation's drawbacks.

Bottlebrush Polyethylene Glycol Nanocarriers Translocate across Human Airway Epithelium via Molecular Architecture-Enhanced Endocytosis.

Pulmonary drug delivery is critical for the treatment of respiratory diseases. However, the human airway surface presents multiple barriers to efficient drug delivery. Here, we report a bottlebrush poly(ethylene glycol) (PEG-BB) nanocarrier that can translocate across all barriers within the human airway surface. Guided by a molecular theory, we design a PEG-BB molecule consisting of a linear backbone densely grafted by many (∼1000) low molecular weight (∼1000 g/mol) polyethylene glycol (PEG) chains; this results in a highly anisotropic, wormlike nanocarrier featuring a contour length of ∼250 nm, a cross-section of ∼20 nm, and a hydrodynamic diameter of ∼40 nm. Using the classic air-liquid-interface culture system to recapitulate essential biological features of the human airway surface, we show that PEG-BB rapidly penetrates through endogenous airway mucus and periciliary brush layer (mesh size of 20-40 nm) to be internalized by cells across the whole epithelium. By quantifying the cellular uptake of polymeric carriers of various molecular architectures and manipulating cell proliferation and endocytosis pathways, we show that the translocation of PEG-BB across the epithelium is driven by bottlebrush architecture-enhanced endocytosis. Our results demonstrate that large, wormlike bottlebrush PEG polymers, if properly designed, can be used as a carrier for pulmonary and mucosal drug delivery.

Enhancing pulmonary delivery and immunomodulation of respiratory diseases through virus-mimicking nanoparticles

This study introduces the nanobromhexine lipid particle (NBL) platform designed for effective pulmonary drug delivery. Inspired by respiratory virus transport mechanisms, NBL address challenges associated with mucus permeation and inflammation in pulmonary diseases. Composed of low molecular weight polyethylene glycol-coated lipid nanoparticles with bromhexine hydrochloride, NBL exhibit a size of 118 ± 24 nm, a neutral zeta potential, osmolarity of 358 ± 28 mOsmol/kg, and a pH of 6.5. Nebulizing without leakage and showing no toxicity to epithelial cells, NBL display mucoadhesive properties with a 60% mucin-binding efficiency. They effectively traverse the dense mucus layer of Calu-3 cultures in an air-liquid interface, as supported by a 55% decrease in MUC5AC density and a 29% increase in nanoparticles internalization compared to non-exposed cells. In assessing immunomodulatory effects, NBL treatment in SARS-CoV-2-infected lung cells leads to a 40-fold increase in anti-inflammatory MUC1 gene expression, a proportional reduction in pro-inflammatory IL-6 expression, and elevated anti-inflammatory IL-10 expression. These findings suggest a potential mechanism to regulate the excessive IL-6 expression triggered by virus infection. Therefore, the NBL platform demonstrates promising potential for efficient pulmonary drug delivery and immunomodulation, offering a novel approach to addressing mucus permeation and inflammation in pulmonary diseases.

Synthesis of chain‐end functionalized highly branched polyethylene waxes using sterically open α‐diimine Ni(II) catalysts

AbstractOur previous research showed that bis(benzocyclopentyl) α‐diimine Pd(II) complexes can facilitate chain transfer and polar monomer insertion in ethylene (co)polymerization. In this study, we synthesized two bis(benzocyclopentyl) α‐diimine Ni(II) complexes with different backbones. The Ni(II) complexes exhibited high activities (0.63–7.23 × 106 g·mol−1 h−1) and produced low molecular weight (2.7–7.8 kg mol−1) polyethylene waxes with high branching densities (43–86/1000 C) in ethylene polymerization. The use of a catalyst with a butyl backbone resulted in polyethylene waxes with significantly higher molecular weights. The axial substituent restriction strategy employed in the nickel catalyst allows for a sterically open structure, reducing the molecular weight of the resulting polyethylene by over two orders of magnitude, compared to ethyl catalysts without axial restrictions. This enables the production of polyethylene wax grade products with improved properties. The branched polyethylene wax chain ends were found to be aryl‐functionalized according to NMR characterization analysis, while the double bonds were absent. Also, the choice of solvent affects the branching, molecular weight, and chain end composition of the polyethylene wax.

A thermostable ionic liquid-methacrylate-based polymer electrolyte for energy storage application

In recent years, gel polymer electrolytes (GPEs) incorporating ionic liquids (ILs) have been explored extensively for lithium-ion batteries due to their favourable thermal stability and high ionic conductivity. Gel polymer electrolytes can also improve the safety of lithium-ion batteries by eliminating the flammable organic solvents which are often used in traditional electrolyte systems. Herein, we report an efficient synthesis of a thermostable ionic liquid-methacrylate-based polymer gel electrolyte via a photo-initiated phase separation (PIPS) process in an inert environment. Anionic liquid phase of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI), coupled with a low molecular weight polyethylene glycol dimethyl ether (PEGDME), was combined with a solid phase of bisphenol A ethoxylate dimethacrylate (BEMA) at varying solid to liquid ratios to produce a thermally stable gel electrolyte. The highest ionic conductivity of 1.9 × 10−3 S cm−1 (at 30 °C) was achieved for the electrolyte with a solid-to-liquid ratio of 1:3 by weight. The Lithium metal cells utilizing these electrolytes and LiFePO4 as cathode active material exhibited the initial discharge capacity of 144 mAh g−1 with capacity retention of 85 % over 100 cycles in ambient temperature. The thermal stability of the cells was significantly improved upon increasing the EMIMTFSI content. This study illustrates the potential application of the IL-methacrylate gel polymer electrolyte system in enhancing the safety of Li-ion batteries through careful tuning of the composition. Their versatile properties also make them suitable for quasi-solid-state batteries with high energy density and safety.

Formability of low-molecular weight polyethylene oxide reinforced by tempo-oxidized nanocellulose for lithium-ion battery solid polymer electrolyte

Formability of low-molecular weight polyethylene oxide reinforced by tempo-oxidized nanocellulose for lithium-ion battery solid polymer electrolyte

Zinc(II)-Quinoline module and ROS cleavable crosslinker functionalized self-fluorescent siRNA vectors for selective gene silencing of cancer cells

A highly efficient siRNA vector (Zn-PQD) capable of selectively silencing genes in cancer cells was obtained by using ROS-cleavable DED to crosslink low molecular weight (LMW) polyethylene imine (PEI) modified by self-fluorescent metal coordinatied multifunctional module Zn-QS. Under the combined action of DED cross-linking and Zn-QS modification, Zn-PQD performs well in the siRNA delivery process in cancer cells, including siRNA condensation, cell uptake, endosome escape, and siRNA release. Zn-PQD exhibited higher transfection efficiency than commercial PEI25k and Lipo2k in multiple cancer cell lines including HepG2, HeLa, 4 T1, H520 and PANC-1, as well as cancer treatment-related stem cell rADSC. Ultimately, Zn-PQD can achieve extremely high and selective gene silencing effects in cancer cells (with a gene silencing rate of 98.3% in HepG2). This work is expected to provide an efficient and safe siRNA carrier for the future tumor siRNA therapy and its study of fluorescence mediated mechanism.

Use of a Low Profile Ultra-High Molecular Weight Polyethylene Diaphyseal Humeral Cement Restrictor in Shoulder Arthroplasty.

When implanting a cemented humeral stem, a reliable method to prevent inappropriate extension and enable pressurization of cement in the intramedullary canal is required. The aim was to assess the outcomes of a dedicated humeral diaphyseal cement restrictor. In total 218 shoulders (207 patients) were included in the study, all of whom underwent a cemented total shoulder arthroplasty and a retrospective review was performed. The primary outcomes of interest were device stability in the medullary canal, successful occlusion of the canal, cement extrusion and quality of cement mantle. The majority of the cohort was female (63.3%) males and the average patient age was 71.7 years (SD 8.45). In 81.7% the device was deemed to be stable in the medullary canal. The device was significantly more stable in primary (84.2%) compared to revision cases (64.3%, p = 0.02). In 69.7% Barrack grade A mantle quality was achieved, this was higher in primary cases (74.2%) compared to revision cases (39.3%) (p = 0.00006). We noted excellent cementation outcomes using a cement restrictor specifically designed for the diaphyseal humerus anatomy. However, this humeral specific restrictor was noted to be more stable in primary as compared to revision cases.

Synthesis of low-molecular weight and branched polyethylenes via ethylene polymerization using 9-(arylimino)-5,6,7,8-tetrahydrocyclohepta-pyridylnickel precatalysts.

Targeting pour point depressants of low-molecular weight and branched polyethylenes, a series of 9-[2,4-bis(benzhydryl)-6-R-phenylimino]-5,6,7,8-tetrahydro-cycloheptapyridine-nickel complexes (Ni1-Ni10) were developed as efficient precatalysts. Upon activation with either EASC or MAO, all nickel complex precatalysts exhibited high activity [up to 8.12 × 106 g PE (mol of Ni)-1 h-1] with single-site behavior toward ethylene polymerization, producing low-molecular weight and unimodal polyethylenes. The resultant polyethylenes possessed high branching with predominant methyl groups and longer chains, along with either internal vinylene or vinyl end groups. The activities of these complex precatalysts were heavily rationalized on the basis of the electronic and steric influences of their 6-R-substituents, with bromides following the order of Ni5 (F) > Ni4 (Cl) > Ni1 (Me) > Ni2 (Et) > Ni3 (iPr) and chlorides following the order of Ni10 (F) > Ni9 (Cl) > Ni6 (Me) > Ni7 (Et) > Ni8 (iPr). DFT calculations revealed the crucial role of agostic interactions (-Ni⋯H-C(Ph2)) between the nickel metal and the hydrogen atom of the ortho bulky group in achieving high catalytic activity and intramolecular hydrogen bonding with the fluoride atom in producing low Mw PE wax. Moreover, the organic compounds and nickel complexes were well characterized, including representative complexes Ni3 and Ni4, via single-crystal X-ray diffraction.

A high performance, stable anion exchange membrane for alkaline redox flow batteries

The development of cost-effective, safe, and low-corrosion alkaline aqueous redox flow batteries, such as alkaline zinc-iron flow batteries, has motivated the research of hydrocarbon-based anion exchange membranes. These membranes, characterized by their positively charged functional groups, facilitate the transport of hydroxide anions (OH−) in alkaline environments, rendering them as potential alternatives to conventional proton exchange membranes in emerging alkaline redox flow batteries. Herein, a facilely synthesized anion exchange membrane (AEM) with superior chemical stability in alkaline media and outstanding ion conductivity has been developed for use in an alkaline redox flow battery. The membrane consists of a partially imidazolium substituted poly (vinylbenzyl chloride) polymer matrix and low molecular weight polyethylene glycol (PEG) additive. The membrane provides positively charged polymer backbone with hydroxide anion as counter ions. The additive PEG not only augments membrane flexibility through interaction with the rigid polymer backbone, but also enhances the conductivity through conducting ions by the alkalized-ether functionality. The optimized anion exchange membrane demonstrates better ionic conductivity of 58.2 mS cm−1 and comparable permeability compared with commercially Nafion117 membrane, enabling promoted energy efficiency (83.5 %), coulombic efficiency (99.85 %) and excellent stability (280 cycles with negligible capacity degradation) of a zinc-iron flow battery at 80 mA cm−2.

Non-destructive covalent surface alkylation of graphitic carbon nitride for enhanced photocatalytic dye degradation in water

Graphitic carbon nitride (g-CN) is a promising material for various applications due to its unique electronic, optical, and photocatalytic properties, tunable by surface modifications. Herein, a novel and straightforward approach to the covalent addition of low molecular weight polyethylene glycol (PEG550) to g-CNs surface following non-destructive chemistry benefiting from simultaneous activation of hydroxyl and free-amine surface groups by a weak base, potassium carbonate, is for the first time described. The resulting g-CN-PEG550 exhibits almost two-fold enhanced water solubility due to 1 PEG550 chain addition for every ∼ 128 g-CN atoms, detected by thermogravimetric analysis. Complementary X-ray photoelectron spectroscopy elemental analysis of the isolated g-CN-PEG550 displays an increased C─O chemical environment attributed to the covalent addition of carbon- and oxygen-rich PEG550 to the g-CN surface. The g-CN-PEG550 photocatalyst performs 2.5-fold better in degrading rhodamine B due to its enhanced light absorption, improved water-dispersibility, and the efficient separation of photogenerated electron-hole pairs compared to the as-prepared g-CN. The study underscores the potential use of covalently PEGylated oxygen-rich g-CNs in photocatalytic applications.

Unraveling the cytotoxicity and cellular uptake of low, medium and high molecular weight polyethylene glycol polymers in MCF-7 cells by green UPLC-MS/MS methods

Unraveling the cytotoxicity and cellular uptake of low, medium and high molecular weight polyethylene glycol (PEG) in cells is important for evaluation of therapeutic efficacy and toxicity of PEGylated drug delivery systems. In this study, cellular uptake of PEG600, PEG2K, PEG4K and PEG10K in MCF-7 cells was first studied by an UPLC-MS/MS assay coupled with collision induced dissociation (CID) in source technique. The CID of PEG in source with high values of declustering potentials generates numerous PEG-related product ions. These PEG-related fragment ions can be further broken into specific product ions in the collision cell as alternative ions for detection of PEG. The quantification of PEG was finally performed with the MRM transition (m/z 221.0 → 89.0). The experimental results indicated that the toxicity of PEG600, PEG2K, PEG4K and PEG10K was not significant at concentrations of 5–1200 μg/mL and the amounts of PEG polymers entry into MCF-7 cells at was small. The greenness of the developed analytical methods was also assessed by Analytical Eco-Scale, Analytical Greenness calculator (AGREE) and Green Analytical Procedure Index (GAPI) in this study.

Cellulose Acetate/Polyethylene Glycol Composite Beads for Efficient Removal of Methylene Blue

The development of eco-friendly and biodegradable adsorbent with excellent adsorption performance is of great importance for the efficient dye removal in wastewater. Herein, an efficient and biodegradable composite adsorbent bead was fabricated from cellulose acetate (CA) modified with low molecular weight polyethylene glycol 200 (PEG200) for the adsorptive removal of methylene blue dye (MB) from aqueous solution. The weight fraction of PEG was varied to investigate the effect of material bead composition on the morphology, molecular structure, crystal phases, thermal stability, mechanical properties, and adsorption performance of the composite beads. Batch adsorption was carried out at various times to estimate the time at equilibrium adsorption capacity and kinetic model. Various operating conditions such as pH, initial MB concentration, and adsorbent dosage in experiment were also executed to examine the adsorption performance of this system. The result showed that all beads have porous structure and the pore size increase after the addition of PEG200. The adsorption capacity and % MB removal generally showed an improvement with the rise of PEG content. The batch adsorption experiments demonstrated that the best % removal and adsorption capacity of MB were 93.35 % and 28.005 mg/g, respectively, that was obtained by composite CA/PEG200 (80/20) bead at pH of 11, initial MB concentration of 30 mg/L, and bead dosage of 1 g/L. The adsorption kinetic fitted well to Elovich-kinetic model with average R2 of 0.844. Overall, this work offers new finding into the development of effective, environmentally friendly, and inexpensive cellulose-based adsorbents for wastewater remediation.

Bio-Resorption Control of Magnesium Alloy AZ31 Coated with High and Low Molecular Weight Polyethylene Oxide (PEO) Hydrogels.

Magnesium AZ31 alloy has been chosen as bio-resorbable temporary prosthetic implants to investigate the degradation processes in a simulating body fluid (SBF) of the bare metal and the ones coated with low and high-molecular-weight PEO hydrogels. Hydrogel coatings are proposed to control the bioresorption rate of AZ31 alloy. The alloy was preliminary hydrothermally treated to form a magnesium hydroxide layer. 2 mm discs were used in bioresorption tests. Scanning electron microscopy was used to characterize the surface morphology of the hydrothermally treated and PEO-coated magnesium alloy surfaces. The variation of pH and the mass of Mg2+ ions present in the SBF corroding medium have been monitored for 15 days. Corrosion current densities (Icorr) and corrosion potentials (Ecorr) were evaluated from potentiodynamic polarisation tests on the samples exposed to the SBF solution. Kinetics of cumulative Mg ions mass released in the corroding solution have been evaluated regarding cations diffusion and mass transport parameters. The initial corrosion rates for the H- and L-Mw PEO-coated specimens were similar (0.95 ± 0.12 and 1.82 ± 0.52 mg/cm2day, respectively) and almost 4 to 5 times slower than that of the uncoated system (6.08 mg/cm2day). Results showed that the highly swollen PEO hydrogel coatings may extend into the bulk solution, protecting the coated metal and efficiently controlling the degradation rate of magnesium alloys. These findings focus more research effort on investigating such systems as tunable bioresorbable prosthetic materials providing idoneous environments to support cells and bone tissue repair.

MODIFICATION OF BITUMINOUS BINDERS WITH PETROCHEMISTRY WASTE

An analysis was made of the possibility of using sludge from the production of sulfonate additives and low
 molecular weight polyethylene for the modification of bituminous materials. It has been established that the combined
 effect of the components of the proposed combined additive on the structure of the bituminous binder makes it possible
 to increase its heat resistance, plasticity and elasticity, with acceptable adhesion to the surfaces of mineral materials.
 Modification of road bitumen with a combined additive based on sludge from the production of a sulfonate additive and
 low molecular weight polyethylene will expand the range of polymer modifiers for polymer-bitumen compositions,
 reduce the involvement of imported additives, reduce the burden on the environment and obtain a positive economic
 effect.

Improved bleached eucalyptus kraft pulp-based tissue papers incorporating wet-strength resins

Abstract Common tissue paper manufacturing trends aim at partial or total replacement of softwood pulp with hardwood pulp for its production, such as bleached eucalyptus kraft pulp (BEKP), in order to optimize the process and the final product properties such as softness. However, the use of a single type of hardwood fiber results in lower strengths of both wet and dry webs. To maintain necessary strength and desired properties, the incorporation of several additives is often required. In this context, low molecular weight polyethylene glycol (PEG) and different wet strength resins, such as polyamideamine-epichlorohydrin (PAE) and glyoxalated polyacrylamide (GPAM) resins, were combined to achieve an innovated product with improved properties. In particular, wet and dry tensile strength was significantly improved when combining PEG and wet strength resins, especially observed in tissue papers prepared with PAE resin, high-charge cationic agent and bulk applied aqueous PEG solution. Noteworthy that water absorption capacity and softness of tissue paper were not critically affected by PEG incorporation, regardless of application method used (in bulk or by spray).

Optical Polymorphism of Liquid-Crystalline Dispersions of DNA at High Concentrations of Crowding Polymer.

Optically active liquid-crystalline dispersions (LCD) of nucleic acids, obtained by polymer- and salt-induced (psi-) condensation, e.g., by mixing of aqueous saline solutions of low molecular weight DNA (≤106 Da) and polyethylene glycol (PEG), possess an outstanding circular dichroism (CD) signal (so-called psi-CD) and are of interest for sensor applications. Typically, such CD signals are observed in PEG content from ≈12.5% to ≈22%. However, in the literature, there are very conflicting data on the existence of psi-CD in DNA LCDs at a higher content of crowding polymer up to 30-40%. In the present work, we demonstrate that, in the range of PEG content in the system above ≈24%, optically polymorphic LCDs can be formed, characterized by both negative and positive psi-CD signals, as well as by ones rather slightly differing from the spectrum of isotropic DNA solution. Such a change in the CD signal is determined by the concentration of the stock solution of PEG used for the preparation of LCDs. We assume that various saturation of polymer chains with water molecules may affect the amount of active water, which in turn leads to a change in the hydration of DNA molecules and their transition from B-form to Z-form.