Variation Of Molecular Weight Research Articles

British Society for Haematology guideline for anticoagulantmanagement of pregnant individuals with mechanical heart valves.

British Society for Haematology guideline for anticoagulantmanagement of pregnant individuals with mechanical heart valves.

The Effect of Accelerated Aging on the Molecular Weight and Thermal and Mechanical Properties of Polyester Yarns Containing Ceramic Particles

The accelerated aging of polyethylene terephthalate (PET) multifilament yarns containing nano or microparticles of titanium dioxide (TiO2), silicon carbide (SiC), or fluorite (CaF2) at a maximum percentage of 2% has been studied. For this, the yarn samples were introduced into a climatic chamber at 50 °C, 50% relative humidity, and an ultraviolet A (UVA) irradiance of 1.4 W/m2. They were then removed from the chamber after periods of between 21 and 170 days of exposure. Subsequently, the variation in weight average molecular weight, number molecular weight, and polydispersity was evaluated by gel permeation chromatography (GPC), the surface appearance was evaluated using scanning electron microscopy (SEM), the thermal properties were evaluated using differential scanning calorimetry (DSC), and the mechanical properties were evaluated using dynamometry. The results showed that, at the test conditions, there was degradation in all of the exposed substrates, possibly due to the excision of the chains that make up the polymeric matrix, which resulted in the variation in the mechanical and thermal properties depending on the type and size of the particle used. This study provides insight into the evolution of the properties of PET-based nano- and microcomposites and might be helpful when selecting materials for specific applications, which is of great interest from an industrial point of view.

Biodegradable Poly(ester) Urethane Acrylate Resins for Digital Light Processing: From Polymer Synthesis to 3D Printed Tissue Engineering Constructs.

Digital light processing (DLP) is an accurate and fast additive manufacturing technique to produce a variety of products, from patient-customized biomedical implants to consumer goods. However, DLP's use in tissue engineering has been hampered due to a lack of biodegradable resin development. Herein, a library of biodegradable poly(esters) capped with urethane acrylate (with variations in molecular weight) is investigated as the basis for DLP printable resins for tissue engineering. The synthesized oligomers show good printability and are capable of creating complex structures with mechanical moduli close to those of medium-soft tissues (1-3MPa). While fabricated films from different molecular weight resins show few differences in surface topology, wettability, and protein adsorption, the adhesion and metabolic activity of NCTC clone 929 (L929) cells and human dermal fibroblasts (HDFs) are significantly different. Resins from higher molecular weight oligomers provide greater cell adhesion and metabolic activity. Furthermore, these materials show compatibility in a subcutaneous in vivo pig model. These customizable, biodegradable, and biocompatible resins show the importance of molecular tuning and open up new possibilities for the creation of biocompatible constructs for tissue engineering.

Plasmid DNA mediated vancomycin-resistant Staphylococcus aureus (VRSA) from cases of urinary tract infection

Vancomycin resistance commonly occurs with Staphylococcus aureus, a pathogen that exhibits intrinsic virulence. Sixty isolates of Staphylococcus aureus tested positive as vancomycin possessive isolates on Brain Heart Infusion Agar medium fortified with 6 μg/mL vancomycin from 100 clinical samples of urine from patients with cases of UTIs via agar diffusion method. Standard 30 μg vancomycin disc served as control. Increase in zones of growth inhibition in relation to vancomycin concentrations was noticed in some of the isolates while it was reversed in others, despite the increase in concentration. Typed strain was susceptible to six concentrations of vancomycin exposed and to the control. Thirty one of the sixty isolates were resistant to vancomycin control. Resistant isolates from standard vancomycin discs were then subjected to molecular investigation. Of the 31 isolates exposed to gel electrophoresis, 14 (47%)elicited plasmids of varied molecular weights ranging from 0.79-23.13 kb. The magnitudes of vancomycinresistant isolates from the clinical samples studied, coupled with some incoherent zones of inhibition and the plasmid DNA obtained from the resistant isolates, suggest the need for infection control practitioners and epidemiologist to devise strategies to curtail the spread of this pathogen both in hospital and community settings.

Prediction of Molecular Weight of Petroleum Fluids by Empirical Correlations and Artificial Neuron Networks

The exactitude of petroleum fluid molecular weight correlations affects significantly the precision of petroleum engineering calculations and can make process design and trouble-shooting inaccurate. Some of the methods in the literature to predict petroleum fluid molecular weight are used in commercial software process simulators. According to statements made in the literature, the correlations of Lee–Kesler and Twu are the most used in petroleum engineering, and the other methods do not exhibit any significant advantages over the Lee–Kesler and Twu correlations. In order to verify which of the proposed in the literature correlations are the most appropriate for petroleum fluids with molecular weight variation between 70 and 1685 g/mol, 430 data points for boiling point, specific gravity, and molecular weight of petroleum fluids and individual hydrocarbons were extracted from 17 literature sources. Besides the existing correlations in the literature, two different techniques, nonlinear regression and artificial neural network (ANN), were employed to model the molecular weight of the 430 petroleum fluid samples. It was found that the ANN model demonstrated the best accuracy of prediction with a relative standard error (RSE) of 7.2%, followed by the newly developed nonlinear regression correlation with an RSE of 10.9%. The best available molecular weight correlations in the literature were those of API (RSE = 12.4%), Goosens (RSE = 13.9%); and Riazi and Daubert (RSE = 15.2%). The well known molecular weight correlations of Lee–Kesler, and Twu, for the data set of 430 data points, exhibited RSEs of 26.5, and 30.3% respectively.

Enzyme-Catalyzed Polymerization of Kraft Lignin from Eucalyptus globulus: Comparison of Bacterial and Fungal Laccases Efficacy.

Kraft lignin, a side-stream from the pulp and paper industry, can be modified by laccases for the synthesis of high added-value products. This work aims to study different laccase sources, including a bacterial laccase from Streptomyces ipomoeae (SiLA) and a fungal laccase from Myceliophthora thermophila (MtL), for kraft lignin polymerization. To study the influence of some variables in these processes, a central composite design (CCD) with two continuous variables (enzyme concentration and reaction time) and three levels for each variable was used. The prediction of the behavior of the output variables (phenolic content and molecular weight of lignins) were modelled by means of response surface methodology (RSM). Moreover, characterization of lignins was performed by Fourier-transform infrared (FTIR) spectroscopy and different nuclear magnetic resonance (NMR) spectroscopy techniques. In addition, antioxidant activity was also analyzed. Results showed that lignin polymerization (referring to polymerization as lower phenolic content and higher molecular weight) occurred by the action of both laccases. The enzyme concentration was the most influential variable in the lignin polymerization reaction within the range studied for SiLA laccase, while the most influential variable for MtL laccase was the reaction time. FTIR and NMR characterization analysis corroborated lignin polymerization results obtained from the RSM.

Novel AD biomarker based on platelets tau: Expanding to plasma detection

AbstractBackgroundAlzheimer’s disease (AD) is the most prevalent cause of dementia in the elderly. One of the major drawbacks of this disease is the lack of molecular biomarkers that could provide of an early detection, as the ones currently available are invasive (CSF biomarkers), not cost‐efficient (neuroimaging, PET scan) and do not provide an early detection. In this work we propose the novel biomarker Alz‐tau®, based on platelet tau, as a non‐invasive and cost‐efficient way for early detection of pathological events that may lead Alzheimer’s disease.MethodsPlasma samples were obtained by centrifugation. Platelets were obtained from blood samples of AD patients and controls, lysed to obtain protein extracts and further processed for a western blot analysis. The immuno‐ detection was performed with a novel monoclonal antibody tau51, which detects two variants of tau protein: a high molecular weight variant (HMW) and a low molecular weight variant (LMW). The results obtained were subjected to a densitometric analysis with ImageJ and the algorithm HWM/LMW was obtained.ResultsWe demonstrated that in platelets the algorithm HWM/LMW was statistically higher in AD patients when compared to controls. Similar results were obtained in plasma. Likewise, the platelet biomarker has a proven sensitivity of 71.43% and a specificity of 69.23%, while a sensibility of 80% and specificity of 66.5% was found in plasma samples.ConclusionsHere, we demonstrate the efficiency and functionality of of a novel, non‐invasive, and cost‐efficient biomarker for early detection of AD, based on 4 clinical trials. The most relevant feature of this biomarker is that it is able to detect alterations before the patient presents any symptoms, thus it would be highly beneficial for prevention of AD.

Dyes removal from textile wastewater by agricultural waste as an absorbent – A review

Water pollution from the textile industry affects environmental conditions by generating large-scale effluent mixed with various dyes. Dyes are mostly organics with multiple compound structural and molecular weight variations; if not managed properly before release, they may harm the environment and organism. However, many dyes are categorized into distinct groups, and various adsorbents for dye adsorption have been identified. Among these dyes, methyl dyes, which come in multiple colours, are the most popular in research due to their availability and accessibility. It is imperative to use effective treatments using special adsorbents to remediate water contamination before discharging into streams. As awareness of environmental issues increases with time, the need for a wide range of adaptive alternative feedstock that satisfies ecological regulations has become a priority for researchers worldwide. Therefore, there is a need to develop other adsorbents from alternatively economic raw materials such as locally available industrial and mineral waste and by-products. Additionally, numerous materials have been used, prepared, or grafted from various agricultural peel-based adsorbents. Biomass is a significant source of renewable adsorption processes for hazardous compounds, including toxic organics and metals/elements. It is much cheaper, has abundance, effective adsorption capability, and reusability, have numerous advantages over conventional materials. This review focuses on using plant agricultural wastes to remove dyes. Different adsorption capacities, operating conditions, and application forms have been investigated. The adsorption kinetics and isotherms are demonstrated to illustrate the adsorbent's properties and adsorption mechanisms. • Agricultural waste is valuable because it is inexpensive, abundant, and resilience and is utilized to adsorb and remove various types of dyes. • The agricultural waste (organic peels, seeds, and leaves) demonstrated its remarkable efficacy in removing contaminants from water. • This research is gaining much attention and prominent.

Iron Oxide Powder as Responsible for the Generation of Industrial Polypropylene Waste and as a Co-Catalyst for the Pyrolysis of Non-Additive Resins

For the synthesis of polymeric resins, it is of great importance to review the raw materials and the equipment to be used to avoid the presence of compounds that may affect the effectiveness of the polymerization and the characteristics of the plastic to be obtained. Iron oxide is a compound that can be present in reactors after maintenance due to the techniques used and the cleaning of this equipment, and it can affect the characteristics of the resins, reducing their quality. In this study, the presence of FeO in different concentrations was evaluated to determine its effects on the properties and pyrolysis of polypropylene resins by using X-ray refraction to determine the elements of the samples, evaluating thermal degradation by TGA, the variation in molecular weight by measuring the MFI, and the compounds obtained from pyrolysis by chromatography. The results showed that the thermal degradation decreased as the FeO concentration increased, while for the MFI, the relationship was directly proportional. The evaluation of the compounds obtained from pyrolysis showed an increase in the production of alcohols, alkynes, ketones, and acids, and a decrease in alkanes and alkenes, showing that FeO affects the properties of polypropylene and the compounds that are produced during pyrolysis.

On the essentiality of the angiotensin converting enzyme 2 receptor for SARS-CoV-2 infection and the potential of soluble angiotensin converting enzyme 2 proteins as universal approach for variants causing COVID-19.

On the essentiality of the angiotensin converting enzyme 2 receptor for SARS-CoV-2 infection and the potential of soluble angiotensin converting enzyme 2 proteins as universal approach for variants causing COVID-19.

Production of paclitaxel-loaded PEG-b-PLA micelles using PEG for drug loading and freeze-drying.

A new approach named PEG-assist is introduced for the production of drug-loaded polymeric micelles. The method is based on the use of PEG as the non-selective solvent for PEG-b-PLA in the fabrication procedure. Both hydration temperature and PEG molecular weight are shown to have a significant effect on the encapsulation efficiency of PTX in PEG4kDa-b-PLA2kDa micelles. The optimal procedure for fabrication includes the use of PEG1kDa as the solvent at 60°C, cooling the mixture to 40°C, hydration at 40°C, freezing at -80°C and freeze-drying at -35°C, 15Pa. No significant difference (p>0.05) in PTX encapsulation, average particle size and polydispersity index is observed between the samples before freeze-drying and after reconstitution of the freeze-dried cake. The prepared PTX formulations are stable at room temperature for at least 8h. Scaling the batch size to 25× leads to no significant change (p>0.05) in PTX encapsulation, average particle size and polydispersity index. PEG-assist method is applicable to other drugs such as 17-AAG, and copolymers of varied molecular weights. The use of no organic solvent, simplicity, cost-effectiveness, and efficiency makes PEG-assist a very promising approach for large scale production of drug-loaded polymeric micelles.

Role of harvest depth filtration in controlling product-related impurities for a bispecific antibody.

BackgroundBispecific antibodies (BsAb) belong to a novel antibody category with advantages over traditional mono-specific therapeutic antibodies. However, product variants are also commonly seen during the production of BsAb, which poses significant challenges to downstream processing. In this study, the adsorptive characteristics of a BsAb product and its variants were investigated for a set of depth filters during primary recovery of the cell culture fluid.MethodsThe retention of the BsAb product and its variants on a set of Millistak+® D0HC and X0HC depth filters were first investigated, followed by studying the mechanism of their adsorption on the depth filters. The chemical and structural properties of depth filters along with the molecular properties of the product and its variants were studied subsequently.ResultsThe X0HC filter was found to be able to retain a significant amount of low molecular weight (LMW) variants along with a low amount of main product retained. Different levels of retention, observed for these variants, were correlated to their different hydrophobic and charge characteristics in relation with the adsorptive properties of the depth filters used. Electrostatic, hydrophobic, and hydrogen bonding interactions were found to be the key forces to keep product variants retained on the depth filter where the higher hydrophobicity of the LMW variants may cause them to be preferentially retained.ConclusionHarvest depth filters potentially can be utilized for retaining the BsAb variants, which depends on relative molecular properties of the product and its variants and adsorptive properties of the depth filters used.

Porphyromonas gingivalis Conditioned Medium Induces Amyloidogenic Processing of the Amyloid-β Protein Precursor upon in vitro Infection of SH-SY5Y Cells

Background:Cleavage of the amyloid-β protein precursor (AβPP) mediated by host secretase enzymes, releases several fragments including amyloid-β (Aβ40 and Aβ42).Objective:To determine if Porphyromonas gingivalis conditioned medium cleaved AβPP to release Aβ40 and Aβ42.Methods:The SH-SY5Y cell line was challenged, in vitro, with P. gingivalis (Pg381) conditioned medium in the presence/absence of cytokines. The cells and their supernatants were assessed for AβPP cleavage fragments by immunoblotting and transmission electron microscopy.Results:Western blotting of the cell lysates with the anti-AβPP C-terminal antibody demonstrated variable molecular weight bands corresponding to full length and fragmented AβPP in lanes treated with the following factors: Tryptic soy broth (TSB), Pg381, IL-6, Pg381 + IL-1β, and Pg381 + TNF-α. The low molecular weight bands corresponding to the C99 dimerized fragment were observed in the Pg381 and interlukin-6 (IL-6) treated groups and were significantly more intense in the presence of Pg381 with either IL-6 or TNF-α. Bands corresponding to the dimerized C83 fragment were observed with cells treated with TNF-α alone and with Pg381 combined with IL-1β or IL-6 or TNF-α. The anti-Aβ antibody detected statistically significant Aβ40 and Aβ42, levels when these two Aβ species were pooled across test samples and compared to the untreated group. Electron microscopic examination of the supernatants demonstrated insoluble Aβ40 and Aβ42.Conclusion:These observations strongly imply that AβPP is an infection responsive protein cleaved via the amyloidogenic pathway on exposure to conditioned medium and in the presence of pro-inflammatory mediators.

Prediction of petroleum viscosity from molecular weight and density

165 crude oils with viscosity, density, and molecular weight variation in the range 0.54 – 24135cP; 0.746 – 1.016 g/cm3; 117–579 g/mol respectively were examined for viscosity prediction using eight available in the literature models and three more, developed in this work models. The best empirical model was that of Sinha et al., 2020 with % AAD (absolute average deviation) = 18.2 %, The ANN (artificial neural network) model for the data set of the 165 crude oils outperformed the empirical correlations with % AAD = 17.7 %. 93 crude oils with viscosity, density, molecular weight, and SARA composition data variation in the range 2.3 – 23 000cP; 0.819 – 0.992 g/cm3; 179–579 g/mol; Sat.: 26.0–79.3 %; Aro:11.9–52.8 %; Res.: 2.5–30.9; Asp.:0.1–19.6 % respectively were also examined for viscosity prediction by the available in the literature empirical correlations and another new developed empirical correlation that includes besides molecular weight and density, the crude oil saturate content. The best empirical model was that developed in this work with saturate content inclusion, that showed % AAD = 23.8 %. The ANN model for the data set of 93 crude oils again outperformed the empirical correlations with % AAD = 18.8 %. The most accurate model predicting viscosity was found the new developed in this work model on the base of a reference viscosity at a particular temperature and molecular weight with %AAD = 2.5 %.

Tuning Diblock Copolymer Particle Packing Symmetry with Variable Molecular Weight Core-Homopolymers

We report the sensitivity of diblock copolymer particle packing symmetry to the ratio α = Nhomo/Ncore, where Nhomo and Ncore are the respective homopolymer and core-block degrees of polymerization. Three poly(ethylene oxide)-b-poly(2-ethylhexyl acrylate) (OA) diblock copolymers with O volume fractions fO = 0.15, 0.16, and 0.20 were blended with O homopolymers characterized by α = 0.23, 0.42, 0.80, and 1.00. Small-angle X-ray scattering revealed rich phase behavior as a function of α, the overall particle core volume fraction (fcore), and temperature. BCC, HCP, and Frank–Kasper σ, C14, C15, and dodecagonal quasicrystal phases, were all identified. “Dry-brush” homopolymer distribution (α = 0.80 and 1.00) favor C14 and C15 phases with macrophase separation at high homopolymer loadings. “Wet-brush” homopolymer distributions in the particle cores (α = 0.42) lead to narrow σ or C15 windows and cylinders at greater O concentrations. Solvent-like swelling (α = 0.23) favors widespread σ phase formation.

Lignin molecular design to transform green manufacturing

<h2>Summary</h2> Lignin is the most abundant phenolic biopolymer on earth, representing an abundant feedstock for green manufacturing. Nevertheless, the diverse chemical linkages, heterogeneous functional groups, variable molecular weights, and amphiphilic structures all prevent the synthesis of fungible materials from lignin, leaving it as a predominantly low-value resource. On the basis of structure-property relationship, we synergistically overcome these challenges by chemical design of a type of lignin, high-molecular weight esterified linkage lignin (HiMWELL), with more uniform esterified linkages, larger molecular weight, and much lower OH group content via interunit substucture replacement. HiMWELL transforms lignin into a precursor for manufacturing renewable materials with drastically improved properties and functionality. The HiMWELL-based carbon fiber achieved a record tensile strength and better mechanical properties than the control polyacrylonitrile carbon fiber. HiMWELL also uniquely improved mechanical properties of the recyclable polymer blends and achieved UV-shading effects.

Rheological behavior of PES/PVP/DMAc solution and PVP structural regulation for hollow fiber membrane

AbstractRheological study plays a significant role in hollow fiber membrane spinning process and membrane structure regulation. In this work, the rheological behaviors of polyethersulfone (PES) spinning solutions added the polyvinylpyrrolidone (grade of PVP‐K30, PVP‐K60, and PVP‐K90) were systematically investigated by rotational rheometry to understand how the PES membrane structure changes. Results show that PVP of variable molecular weights change the rheological properties of PES spinning solution, such as the viscosity (ηa), non‐Newtonian index (n), flow activation energy (Eη), structural viscosity index (∆η), storage modulus (G′), and loss modulus (G′′). The mixture with PVP‐K30 exhibits optimal spinnability but the finger‐like membrane structure is undesirable for the hemodialysis. The rheological behaviors of PES/PVP‐K60 and PES/PVP‐K90 reveal that increasing shear rate and temperature are effective ways to improve the spinnability of the mixture and the membrane structure is regulated. Meanwhile, the addition of PVP‐K60 or PVP‐K90 at their critical concentration to the PES solution can fabricate a hollow membrane with a sponge‐like structure. Combining spinnability and membrane structure, PVP‐K90 is a suitable additive for the hemodialysis membrane.

Poly(2‐(dimethylamino) ethyl methacrylate)‐b‐poly(lauryl methacrylate)‐b‐poly(oligo ethylene glycol methacrylate) triblock terpolymer micelles as drug delivery carriers for curcumin

AbstractThis work aims to investigate the ability of poly[2‐(dimethylamino)ethyl methacrylate‐b‐lauryl methacrylate‐b‐(oligo ethylene glycol)methacrylate], PDMAEMA‐b‐PLMA‐b‐POEGMA amphiphilic triblock terpolymers, to encapsulate the model hydrophobic compound curcumin. The terpolymers were synthesized by RAFT polymerization methodologies at variable molecular weights and compositions and self‐assemble into spherical micelles with mixed PDMAEMA/POEGMA coronas and PLMA cores, when inserted in aqueous solutions. Fourier transform infrared and UV–Vis spectroscopy measurements were utilized in order to confirm and quantify the encapsulation of curcumin within the polymeric micelles respectively. Dynamic light scattering was used for the investigation of the size of the nanostructures formed and transmission electron microscopy proved that their morphology is spherical. Moreover, the colloidal stability of the systems in physiological conditions was assessed and two independent in vitro cytotoxicity assays revealed that curcumin‐loaded PDMAEMA‐b‐PLMA‐b‐POEGMA micelles were not cytotoxic.

Synthesis and Thermal Analysis of Non-Covalent PS-b-SC-b-P2VP Triblock Terpolymers via Polylactide Stereocomplexation.

Polylactides (PLAs) are thermoplastic materials known for their wide range of applications. Moreover, the equimolar mixtures of poly(L-Lactide) (PLLA) and poly(D-Lactide) (PDLA) can form stereocomplexes (SCs), which leads to the formation of new non-covalent complex macromolecular architectures. In this work, we report the synthesis and characterization of non-covalent triblock terpolymers of polystyrene-b-stereocomplex PLA-b-poly(2-vinylpyridine) (PS-b-SC-b-P2VP). Well-defined ω-hydroxy-PS and P2VP were synthesized by “living” anionic polymerization high-vacuum techniques with sec-BuLi as initiator, followed by termination with ethylene oxide. The resulting PS-OH and P2VP-OH were used as macroinitiators for the ring-opening polymerization (ROP) of DLA and LLA with Sn(Oct)2 as a catalyst to afford PS-b-PDLA and P2VP-b-PLLA, respectively. SC formation was achieved by mixing PS-b-PDLA and P2VP-b-PLLA chloroform solutions containing equimolar PLAs segments, followed by precipitation into n-hexane. The molecular characteristics of the resulting block copolymers (BCPs) were determined by 1H NMR, size exclusion chromatography, and Fourier-transform infrared spectroscopy. The formation of PS-b-SC-b-P2VP and the effect of molecular weight variation of PLA blocks on the resulting polymers, were investigated by differential scanning calorimetry, X-ray powder diffraction, and circular dichroism spectroscopies.

Hyaladherins May be Implicated in Alcohol-Induced Susceptibility to Bacterial Pneumonia.

Although the epidemiology of bacterial pneumonia and excessive alcohol use is well established, the mechanisms by which alcohol induces risk of pneumonia are less clear. Patterns of alcohol misuse, termed alcohol use disorders (AUD), affect about 15 million people in the United States. Compared to otherwise healthy individuals, AUD increase the risk of respiratory infections and acute respiratory distress syndrome (ARDS) by 2-4-fold. Levels and fragmentation of hyaluronic acid (HA), an extracellular glycosaminoglycan of variable molecular weight, are increased in chronic respiratory diseases, including ARDS. HA is largely involved in immune-assisted wound repair and cell migration. Levels of fragmented, low molecular weight HA are increased during inflammation and decrease concomitant with leukocyte levels following injury. In chronic respiratory diseases, levels of fragmented HA and leukocytes remain elevated, inflammation persists, and respiratory infections are not cleared efficiently, suggesting a possible pathological mechanism for prolonged bacterial pneumonia. However, the role of HA in alcohol-induced immune dysfunction is largely unknown. This mini literature review provides insights into understanding the role of HA signaling in host immune defense following excessive alcohol use. Potential therapeutic strategies to mitigate alcohol-induced immune suppression in bacterial pneumonia and HA dysregulation are also discussed.