Changes In Molecular Weight Research Articles

Hydrolysis of Poly(ester urethane): In-depth Mechanistic Pathway Determination through Thermal and Chemical Characterization

Many structure/property relationships of hydrolyzed poly(ester urethane) (PEU) – a thermoplastic polymer have been reported. Examples include changes in molecular weight vs. elongation at break and crosslink density vs. mechanical strength. However, the effect of molecular weight reduction on some physical, thermal, and chemical properties of hydrolyzed PEU have not been reported. Therefore, a large set of hydrolyzed PEU (Estane®5703) samples were obtained from two aging experiments: 1) accelerated aging conducted under various environments (air, nitrogen, moisture) and at 64°C and below for almost three years, and 2) natural aging conducted under ambient conditions for more than four decades. The hydrolyzed samples were characterized via multi-detection gel permeation chromatography (GPC), thermogravimetric analysis (TGA), modulated differential scanning colorimetry (mDSC), UV-vis spectroscopy, nuclear magnetic resonance (NMR), and Fourier-transform infrared (FTIR) spectroscopy techniques. Hydrolysis of ester linkages in the soft-segments decreases both the molecular weight of the polymer and the melting point of Estane from ∼55°C to 39°C. Aging above this melting temperature (Tm), increased mobility of polymer chains and water diffusivity alter the PEU degradation pathway from those expected at aging temperatures below Tm and have significant bearing on the critical molecular weight (MC) at which the physical, chemical, thermal, and mechanical properties of Estane change abruptly. While a MC value of 20 kDa is found for PEU hydrolysis at mild temperatures (e.g., below 39°C), the MC increases with increasing aging temperature. To complement the existing structure/property relationships reported in the literature, more correlations are obtained, which include the effect of Mw on polydispersity, intrinsic viscosity (Mark-Houwink equation), UV extinction coefficient, and dn/dc (GPC analysis) values. Furthermore, we seek to augment previously reported aging models for PEU by developing a practical model with which the extent of degradation and material performance can be predicted based on aging under different temperature ranges both above and below the melting point of the hard-segments.

Structural and physicochemical properties of plant-based meat analogues from transglutaminase-modified soybean protein

Plant-based meat analogues (PBMA) have been developed for decades. The resemblance in PBMA to meat, in terms of physical properties and sensory attributes, is important for consumers. This study aims to investigate the effects of transglutaminase (TG) concentration (1, 3, 5% (w/w)) on modified textured vegetable soybean protein (TVP). The changes in TVP protein molecular weight, microstructure, texture profile, sensory quality and nutritional value of PBMA were investigated. The first set of analyses examined the impact of TG concentration on TVP structure and the results showed that the TVP protein band from SDS-PAGE were changed to a larger band at 36-40 kDa as compared to the control indicating the formation of a cross-linked protein. The modified TVP was used as a raw ingredient for PBMA development. The appearance and microstructure of PBMA from the TG-modified TVP showed that the uncooked PBMA with TG-modified TVP were not different from those of the control. With regard to the texture profile of PBMA, an increase in TG concentration resulted in an increase in hardness. A sensory evaluation revealed that the PBMA with 1%TG provided the highest overall acceptance score. Hence, the PBMA with 1%TG was selected for a nutritional analysis comparing steak to meat. The carbohydrate and fat content of PBMA with 1%TG were higher than those of meat while the protein content of PBMA with 1%TG consisted of a maximum of 70% meat. This research could lead to alternative plant-based foods in the food industry.

Mechanical deviation in 3D-Printed PLA bone scaffolds during biodegradation

Large or carcinogenic bone defects may require a challenging bone tissue scaffold design ensuring a proper mechanobiological setting. Porosity and biodegradation rate are the key parameters controlling the bone-remodeling process. PLA presents a great potential for geometrically flexible 3-D scaffold design. This study aims to investigate the mechanical variation throughout the biodegradation process for lattice-type PLA scaffolds using both experimental observations and simulations. Three different unit-cell geometries are used for creating the scaffolds: basic cube (BC), body-centered structure (BCS), and body-centered cube (BCC). Three different porosity ratios, 50 %, 62.5 %, and 75 %, are assigned to all three structures by altering their strut dimensions. 3-D printed scaffolds are soaked in PBS solution at 37 °C for 15, 30, 60, 90, and 120 days both unloaded and under dead load. Water absorption, weight loss, and compression stiffness are measured to characterize the first-stage degradation and investigate the possible influences of these parameters on the whole biodegradation process. The strength reduction stage of biodegradation is simulated by solving pseudo-first-order kinetics-based molecular weight change equation using FEA with equisized cubic (voxel-like) elements.For the first stage, mechanical load does not have a statistically significant effect on biodegradation. BCC with 62.5 % porosity shows a maximum water absorption rate of around 25 % by the 60th day which brings an advantage in creating an aquatic environment for cell growth. Results indicate a significant water deposition inside almost all scaffolds and water content is determined to be the main reason for the retained or increased compression stiffness. A distinguishable stiffness increase in the initial degradation process occurs for 75 % porous BC and 50 % porous BCC scaffolds. Following the quasi-stable stage of biodegradation, almost all scaffolds lost their rigidity by around 44–48 % within 120 days based on numerical results. Therefore, initial stiffness increase in the quasi-stable stage of biodegradation can be advantageous and BCC geometry with a porosity between 50% and 62 % is the optimum solution for the whole biodegradation process.

Storms and convection on Uranus and Neptune: Impact of methane abundance revealed by a 3D cloud-resolving model

Context. Uranus and Neptune have atmospheres dominated by molecular hydrogen and helium. In the upper troposphere (between 0.1 and 10 bar), methane is the third main molecule, and it condenses, yielding a vertical gradient in CH4 . As this condensable species is heavier than H2 and He, the resulting change in mean molecular weight due to condensation serves as a factor countering convection, which is traditionally considered as governed by temperature only. This change in mean molecular weight makes both dry and moist convection more difficult to start. As observations also show latitudinal variations in methane abundance, one can expect different vertical gradients from one latitude to another. Aims. In this paper, we investigate the impact of this vertical gradient of methane and the different shapes it can take, including on the atmospheric regimes and especially on the formation and inhibition of moist convective storms in the troposphere of ice giants. Methods. We developed a 3D cloud-resolving model to simulate convective processes at the required scale. This model is nonhydrostatic and includes the effect of the mean molecular weight variations associated with condensation. Results. Using our simulations, we conclude that typical velocities of dry convection in the deep atmosphere are rather low (on the order of 1 m/s) but sufficient to sustain upward methane transport and that moist convection at the methane condensation level is strongly inhibited. Previous studies derived an analytical criterion on the methane vapor amount above which moist convection should be inhibited in saturated environments. In ice giants, this criterion yields a critical methane abundance of 1.2% at 80 K (this corresponds approximately to the 1 bar level). We first validated this analytical criterion numerically. We then showed that this critical methane abundance governs the inhibition and formation of moist convective storms, and we conclude that the intensity and intermittency of these storms should depend on the methane abundance and saturation. In the regions where CH4 exceeds this critical abundance in the deep atmosphere (at the equator and the middle latitudes on Uranus and at all latitudes on Neptune), a stable layer almost entirely saturated with methane develops at the condensation level. In this layer, moist convection is inhibited, ensuring stability. Only weak moist convective events can occur above this layer, where methane abundance becomes lower than the critical value. The inhibition of moist convection prevents strong drying and maintains high relative humidity, which favors the frequency of these events. In the regions where CH4 remains below this critical abundance in the deep atmosphere (possibly at the poles on Uranus), there is no such layer. More powerful storms can form, but they are also a bit rarer. Conclusions. In ice giants, dry convection is weak, and moist convection is strongly inhibited. However, when enough methane is transported upward, through dry convection and turbulent diffusion, sporadic moist convective storms can form. These storms should be more frequent on Neptune than on Uranus because of Neptune’s internal heat flow and larger methane abundance. Our results can explain the observed sporadicity of clouds in ice giants and help guide future observations that can test the conclusions of this work.

In vitro dynamic digestion properties and fecal fermentation of Dictyophora indusiata polysaccharide: Structural characterization and gut microbiota

The in vitro dynamic digestive model more realistically simulates the human digestive system compared to static digestive model. In this study, the dynamic in vitro stomach-intestine digestive system and fecal fermentation was used to investigate the dynamic digestion properties and fermentation properties of Dictyophora indusiata polysaccharide. The results showed that there were no significant changes in molecular weight, functional groups and surface morphology after the in vitro dynamic simulated digestion, indicating that D. indusiata polysaccharide maintained a relatively stable structure during the dynamic in vitro salivary-gastrointestinal digestion. In addition, D. indusiata polysaccharide improved the abundance of beneficial bacteria, including Blautia, Coprobacter and Fusicatenibacter. It is remarkable that D. indusiata polysaccharide significantly increased the level of acetic acid and propionic acid. In conclusion, these results suggested that D. indusiata polysaccharide was a potential source of prebiotics, which provides a basis for the development of D. indusiata polysaccharide in the food or medical field.

The effect of carbon black on degradation of pipe grade black polyethylene in high concentration chlorine dioxide solutions

In this research, the impact of carbon black on the accelerated degradation of pipe grade polyethylene (PE100) exposed to high levels of chlorine dioxide (150 ppm) is examined. Tensile testing reveals a faster degradation rate in black samples compared to neat samples, indicating a detrimental effect of carbon black aggregates on the polymer's aging process. Rheological analysis shows changes in molecular weight and structure due to chemical degradation and chain scission and can be a reliable method for detecting slight changes in molecular structure. Isothermal crystallization shows a slowdown in crystallization kinetics at first, explained by gel-formation due to crosslinking which hinder the crystallization, and then an increase in the kinetics as apparently the chain scission gets dominant again. Neat samples exhibit a higher density of tie molecules, indirectly revealed by much more fibrils in crack wall observed in FESEM images, suggesting better resistance to chemical degradation while the black sample shows a much less fibrillar crack wake and becomes almost completely devoid of any fibrils at later stages of aging. The fibrils, which essentially offer a load-bearing role against the widening and growth of the crack play a key role in resistance to slow crack growth (SCG). Therefore, the higher SCG resistance is expected for neat grade compared to black samples. The study proposes a dual-layer pipe design with a UV-resistant black outer layer and an oxidation-resistant neat inner layer to prolong the lifespan of PE100 pipes by protecting against UV radiation and chemical reactions. This solution offers increased durability, lower maintenance costs, and environmental sustainability benefits.

A multi-analytical approach to evaluate the removal efficiency of polystyrene nanoparticles in water treatment processes

The removal of nanoplastics (NP) from water using various treatment processes has gained significant attention recently. This study comprehensively characterizes the degradation of polystyrene nanoparticles (concentration: 200 ppm, diameter: 140 nm) through UVC irradiation. For the first time, we compared four analytical methods to monitor removal efficiency: Py-GCMS, UV–Visible spectroscopy, TOC, and Turbidity. Additionally, DLS, TEM, and SEC were used to understand changes in particle size, morphology, and molecular weight. Results showed that Py-GCMS overestimated the removal rate by a factor of 2 compared to Turbidity and UV–Visible measurements, which were in agreement. Furthermore, after 200 h of irradiation, the styrene signal disappears from the pyrogram, although the mineralization rate reaches only 50%, as determined by total organic carbon (TOC) analysis. The particle size decreased slowly, reaching 100 nm after 150 h, while a significant decrease in molecular weight indicated high chain-scission. These findings emphasize the importance of a multi-analytical approach to accurately assess NP removal efficiency and understand degradation mechanisms.

Simultaneous adsorption of cadmium, zinc, and lead ions from aqueous solution by Montmorillonite clay coated with [formula omitted] nanoparticles

In this work, Montmorillonite (MMt) coated with MgCuAl-layered double hydroxide (LDH) nanoparticles as a new adsorbent (MCA-LDH@MMt) was synthesized via a low supersaturation characterized using BET, TEM, XRD, SEM/EDS, and FT-IR analysis. The adsorption studies were conducted in a ternary-batch system of three heavy metal ions (cadmium, zinc, and lead). The results showed that the MMt was successfully loaded with MgCuAl nanoparticles with a porosity of 44.63 % and a specific surface area of 76.63 m2/g. In addition, the surface morphology analysis showed that there were several changes in elemental dispersion, molar ratio, and molecular weights during the preparation of the used adsorbent. The influence of environmental parameters on the adsorption behavior was studied in detail, whereby the maximum adsorption capacity for the three metals ions was achieved at pH 5, 120 min contact time, 0.2 g/100 mL dose, and 50 mg/l initial metal ion concentration at 25 ± 1 °C. A pseudo-second-order model well correlates the kinetic data of the three metal ions (R2 > 0.991). The Cd2+ and Zn2+ isotherm data exhibited high compatibility with the Langmuir model, while the Freundlich model better fitted the Pb2+ isotherm data. The maximum adsorption capacity from the Langmuir model was 91.6, 164.9, and 129.2 mg/g for Cd2+, Zn2+, and Pb2+, respectively. Also, the adsorption process of the three metal ions onto MCA−LDH@MMt was primarily characterized by their spontaneous and exothermic nature. In conclusion, this study demonstrated that MCA-LDH@MMt is an effective adsorbent for the simultaneous adsorption of cadmium, zinc, and lead in aqueous solution, with the ability to recover the synthesized adsorbent after four consecutive cycles with a minimal reduction in adsorption ability.

Insights of mechanism and kinetics of acrylonitrile aqueous precipitation polymerization

Aqueous precipitation polymerization is commonly used in the industry due to its efficient heat dissipation, reaction stability and production flexibility. However, its mechanisms and kinetics are still partially unclear. The ammonium persulfate-ammonium sulfite monohydrate (APS-AS) initiated aqueous phase precipitation polymerization of acrylonitrile (AN) at low concentration was deeply investigated, with the APS initiation system as a control. The apparent kinetic equations for the APS and APS-AS initiation systems were determined to be Rp= K[AN]1.706[(NH4)2S2O8]0.704 and Rp= K[AN]3[(NH4)2S2O8]0.704[(NH4)2S2O3]−1.055, respectively. Monitoring AN distribution in the aqueous and polyacrylonitrile (PAN) phases revealed a rapid transition of the reaction site from the aqueous phase to the PAN phase following polymer precipitation. Zeta potential and primary particle number exposed that the nucleation site disparities between initiation systems led to different predominant factors affecting the polymerization rate. The change in molecular weight during polymerization had a maximum due to its dependence on the monomer concentration. The crystallinity of the product initially increased during polymerization, then decreased and eventually stabilized. Scanning electron microscopy (SEM) revealed that the diameter of the internal particles was larger, while the surface particles were smaller after coagulation. These findings offer crucial insights for optimizing aqueous precipitation polymerization and PAN particle property control.

Poly(lactic acid)/poly(vinyl butyral) composites containing kaolin modified by acids and calcination

AbstractThe compatibility between two distinct polymers in the blend is important to maximize various properties of the blends. This study investigated the effects of kaolin modifications through acid and calcination treatments on the compatibility, molecular weight, its distribution, and various properties of poly(lactic acid) (PLA)/poly(vinyl butyral) (PVB) blends. In addition, the incorporation of the modified kaolin as a compatibilizer into the blends enhanced their mechanical and thermal properties, addressing the challenges of immiscibility between distinct polymers. The experimental approach included the utilization of scanning electron microscopy, gel permeation chromatography, differential scanning calorimetry, x‐ray diffraction, Fourier transform infrared spectroscopy, rheometer, and melt flow index to examine the structural, molecular, and thermal, mechanical and rheological behaviors of the composites. The changes in various molecular weights were correlated with other properties. The incorporation of surface‐treated kaolin into the blend improved the compatibility between PLA and PVB, exhibiting a singular melting temperature peak and a less distinct interface between two different polymers. This research contributed to the development of sustainable material solutions by demonstrating the potential of modified inorganic fillers in improving the performance of biodegradable polymer blends.

Green synthesis of Bio-CuS quantum dots by sulfate reducing bacteria for solid-phase photocatalytic degradation of polyethylene film

In this study, CuS quantum dots (QDs) synthesized through biological method were used as photocatalysts for the photocatalytic degradation of polyethylene (PE) plastics. Bio-CuS QDs were synthesized through a green process using sulfate reducing bacteria, while Che-CuS QDs were prepared by chemical precipitation for comparison. The crystal structure, surface morphology, microstructure and optical properties of the samples were detected by XRD, SEM, TEM and UV–Vis DRS. The green synthesis mechanism of Bio-CuS was inferred by analyzing changes in amino acid concentration and the three-dimensional fluorescence spectra of extracellular polymeric substances before and after synthesis. The photocatalytic degradation of PE films by Che-CuS and Bio-CuS was investigated. The weight loss rates of PE+Che-CuS and PE+Bio-CuS were 9.1 % and 12.8 % after 14 d irradiation, respectively, while pure PE was only 1.7 %. Furthermore, SEM, UV–Vis DRS, contact angle, TGA, GPC and FTIR were adopted to characterize the PE film. The results revealed that PE+Che-CuS and PE+Bio-CuS underwent major changes in morphology, transparency, hydrophilicity, thermal stability, molecular weight and functional groups compared with PE, with more pronounced changes observed for PE+Bio-CuS. The quenching experiments of active species showed that h+ and·OH were critical to the PE degradation. The intermediate products of PE degradation were analyzed by GC–MS, and a possible degradation pathway was proposed. In addition, the possible mechanism of photocatalytic degradation of PE films by CuS QDs was proposed. This work provides a green remediation approach to addressing the growing plastic pollution in the environment.

Effect of crosslinker molecular weight on the characteristics of thermoelectric ionogels

Abstract The present study investigates an ionic thermoelectric gel with adjustable functionality through the manipulation of crosslinker molecular weight. The thermoelectric properties of 2-hydroxyethyl acrylate (2-HEA) ionogels, prepared using PEGDA200, PEGDA575, and PEGDA1000 as crosslinkers, were thoroughly examined. Furthermore, dynamic thermal mechanical analysis (DMA) and X-ray diffraction (XRD) techniques were employed to elucidate the underlying reasons for variations in the thermoelectric material properties resulting from changes in crosslinker molecular weight. Notably, the thermoelectric gel synthesized with PEGDA575 exhibited a remarkable thermal power output of 19.19 mV•K-1 along with a tensile capacity of 231%. Additionally, the developed ionic thermoelectric capacitor demonstrated an impressive energy density of 4.288 J•m−2, thereby showcasing its potential application in flexible low-grade heat energy recovery devices.

Digital Light Processing Resins with Programmable Shape Memory for Biomedical Applications.

The creation of biodegradable and biocompatible shape memory polymers amenable to biofabrication techniques remains a challenge. The ability to create shape-changing biodegradable objects that are triggered at body temperature opens up possibilities in tissue engineering, minimally invasive surgery, and actuating bioimplants. Merging Digital Light Processing (DLP) printing with shape memory polymers brings us closer to new smart biomedical outcomes. Previously, we developed a poly(caprolactone-co-trimethylenecarbonate) urethane acrylate resin for the DLP fabrication of biodegradable 3D objects. In further studies, we observed that some of these resins possessed shape memory properties, triggered by body temperature (37 °C). In this subsequent study, we explored the shape memory properties and tunability of this resin family via changes in copolymer composition, molecular weight, and identity of the acrylate end-capping unit. We found that we could create a library of shape memory resins, amenable to DLP printing, which allowed the creation of shape-actuating structures with some tunability over the speed of shape memory and mechanical properties. We observed that increased mole fraction of caprolactone in the copolymer and increased molecular weight of the polymer led to a decrease in speed of the shape memory switch. Furthermore, we observed a trade-off between the composition and the end-capping moiety on the mechanical properties of the polymers. These polymeric resins were able to be processed into shapes that were able to perform work, including the release of cargo and grabbing/lifting of an object. This platform now provides a way to tune the speed and mechanical properties of a shape memory DLP object created from common and scalable polymerization techniques. This work ultimately provides a new platform to develop customizable and biodegradable devices capable of actuating and delivery devices for numerous biomedical applications.

A simple predictive three-step chemical model for gaseous stoichiometric hydrogen–oxygen detonation quenching

Two types of three-step chain-branching kinetics for gaseous hydrogen–oxygen detonation quenching are proposed. The reaction rates dependency on density and pressure, as well as the change in molecular weight are included and fitted to results of detailed chemistry not only along the Hugoniot curve but also behind transverse waves. The trend of induction and reaction times and reduced activation energy of zero-dimensional constant pressure combustion process as well as the induction, reaction lengths, and peak thermicity of the ZND model are focused on in the calibration procedure. One model (3SM-I) is designed to model the ideal detonation whereas the other (3SM-N) focuses on the Dn−κ curve during calibration, i.e. the detonation velocity-mean front curvature curves, aiming to capture the non-idealities. The predictive ability using the proposed models is evaluated in a detonation transmission configuration, a layer of ▪ mixture being confined by N2, in determining the critical height, reactive layer height at which detonation transmission is not possible. Both approaches get closer to the critical height from detailed chemistry. With the present set of model parameters, 3SM-I is better than 3SM-N for prediction of critical height. Moreover, borrowing analytical ignition criteria and wave hierarchy approach, the comparison of various chemical models that are able to recover the critical height suggests that the slope of the Dn−κ curve, linked with the chemical response to losses, is the first key parameter for the critical height determination. In addition, the dynamics of the extinction near criticality such as appearance of transverse detonation and quenching distance from 3SM-I are in very good agreement with that of detailed chemistry due to better estimation of the chemical features along the Hugoniot curve and behind transverse waves. The present study provides a guideline to get simplified chemical models from detailed chemistry for predictive simulations.Novelty and significance statementThe novelty of research is two-fold. The first is to provide general guideline to get simplified models from detailed chemistry for the simulation of detonation extinction with improved predictive ability. The tested configuration was that of a stoichiometric hydrogen–oxygen mixture semi-confined by nitrogen. The evolution of the induction, reaction times, and the maximum thermicity were used as fitting targets for our 3-step model. Furthermore, they were evaluated not only at the post-shock states along the Hugoniot curve, but also behind the transverse waves, keystones of the cellular structure. Second, borrowing analytical ignition criteria and wave hierarchy approach, the comparison of different chemical models that were able to recover the critical height suggested that the slope of the normal velocity–curvature curve was the first key parameter for the critical height determination. Moreover, the dynamics of extinction near criticality, and quenching distance depended on the reaction rate dependency on density and pressure.

Laser sintering of polyamide 12 with limited thermal degradation

The paper presents, for the first time, the results of PA12 polyamide sintering using the original method of Dual Beam Laser Sintering of polymers (DBLS). The DBLS method, which is a modification of the standard polymer Laser Sintering (pLS) approach, allows to reduce the thermal degradation of the polymer by using selective (in terms of powder volume and process time) heating the material with laser radiation. The paper presents both the properties of sintered parts and the analysis of the degree of thermal degradation of post-process powders. Examination of the sintered parts included X-ray computed tomography (XCT) to visualize and analyze their porosity and a tensile test. Post-process powders were evaluated by Gel Permeation Chromatography (GPC), Melt Flow Rate (MFR), Dry Laser Diffraction Spectroscopy (DLD) and Powder Rheometer (FT4). The analysis of the result of PA12 sintering with the DBLS method was carried out in comparison with the classic pLS approach. As it has been shown, the DBLS approach allows to obtain comparable results for sintered parts compared to the pLS method. What is particularly important, it was shown that the post-process powder in the DBLS method has almost unchanged properties - the change in molecular weight and viscosity is at the level of the measurement error. Reducing thermal degradation is especially important in order to obtain continuous circulation of the powder in the manufacturing process.

Advancing Fab-Compatible Color-Selective Organic Photodiodes: Tailored Molecular Design and Nanointerlayers.

High-performance organic photodiodes (OPDs) and OPD-based image sensors are primarily realized using solution processes based on various additives and coating methods. However, vacuum-processed OPDs, which are more compatible with large-scale production, have received little attention, thereby hindering their integration into advanced systems. This study introduces innovations in the material and device structures to prepare superior vacuum-processed OPDs for commercial applications. A series of vacuum-processable, low-cost p-type semiconductors is developed by introducing an electron-rich cyclopentadithiophene core containing various electron-accepting moieties to fine-tune the energy levels without any significant structural or molecular weight changes. An additional nanointerlayer strategy is used to control the crystalline orientation of the upper-deposited photoactive layer, compensating for device performance reduction in inverted, top-illuminated OPDs. These approaches yielded an external quantum efficiency of 70% and a specific detectivity of 2.0 × 1012 Jones in the inverted structures, which are vital for commercial applications. These OPDs enabled visible-light communications with extremely low bit error rates and successful X-ray image capture.

Biodegradable composites fabricated using recycled poly(lactic acid)-based single-use coffee cup and regenerated cellulose fiber

ABSTRACT A series of biodegradable composites, including maleic acid-grafted recycled poly(lactic acid) (g-rPLA) and chemically modified lyocell (m-lyocell), were successfully synthesized. The rPLA was obtained from waste PLA-based single-use coffee cups. The storage modulus at −20°C of g-rPLA was increased from 1920 MPa for pure PLA to 3370 MPa for 5 wt% g-rPLA/m-lyocell composites, which is more than 75% enhancement. The number-average molecular weight after photodegradation for 60 days of g-rPLA and 5 wt% g-rPLA/m-lyocell composites was decreased by about 67.12% and 26.17% as compared to the samples before photodegradation, respectively. The results of photodegradations for composites indicate that the change of number-average molecular weight after photodegradation decreased by increasing the loading of m-lyocell. This result suggests that the existence of m-lyocell improved the UV protection ability of the g-rPLA. With the enhancement of mechanical properties and UV protection ability, this work provides an appropriate approach for the applications to reuse the waste PLA-based single-use coffee cups.

Effects of polyvinylpyrrolidone additive on structures and properties of Poly(m-phenylene isophthalamide) hollow fiber membranes -experiment observation and computation approach

This study systematically investigates the effect of introduction of polyvinylpyrrolidone (PVP) used as a hydrophilic additive and its molecular weight change on the morphological, mechanical properties, and membrane performances of poly(m-phenylene isophthalamide) (PMIA) hollow fiber (HF) membranes prepared by dry-jet wet spinning method. The results of the morphological and mechanical properties clearly show an increased proportion of a sponge-like pore structure and an overall improvement in the mechanical properties of the PMIA HF membranes with higher molecular weight PVP, respectively. Interestingly, molecular dynamics simulation showed that the presence of PVP within the PMIA matrix activated the overall movement of PMIA molecules, suggesting that the overall flexibility of the system, which can potentially inhibit the collapse of relatively brittle membranes, is increased by the presence of PVP. Finally, as the molecular weight of PVP increases, a typical trade-off phenomenon is observed on PMIA HF membranes, where the water permeability decreases while the rejection rate increases. Based on these results, the findings on the influence of PVP additive and its potential as a reinforcing agent observed in this study through experimental analysis and computational approaches are expected to provide new insights into the development of high-performance polymeric HF membranes.

Simple and fast one-step FRET assay of therapeutic mAb bevacizumab using anti-idiotype DNA aptamer for process analytical technology

We developed an aptamer-based fluorescence resonance energy transfer (FRET) assay capable of recognizing therapeutic monoclonal antibody bevacizumab and rapidly quantifying its concentration with just one mixing step. In this assay, two fluorescent dyes (fluorescein and tetramethylrhodamine) labeled aptamers bind to two Fab regions on bevacizumab, and FRET fluorescence is observed when both dyes come into close proximity. We optimized this assay in three different formats, catering to a wide range of analytical needs. When applied to hybridoma culture samples in practical settings, this assay exhibited a signal response that was concentration-dependent, falling within the range of 50–2000 μg/mL. The coefficients of determination (r2) ranged from 0.998 to 0.999, and bias and precision results were within ±24.0 % and 20.3 %, respectively. Additionally, during thermal and UV stress testing, this assay demonstrated the ability to detect denatured samples in a manner comparable to conventional Size Exclusion Chromatography. Notably, it offers the added advantage of detecting decreases in binding activity without changes in molecular weight. In contrast to many existing process analytical technology tools, this assay not only identifies bevacizumab but also directly measures the quality attributes related to mAb efficacy, such as the binding activity. As a result, this assay holds great potential as a valuable platform for providing highly reliable quality attribute information in real-time. We consider this will make a significant contribution to the worldwide distribution of high-quality therapeutic mAbs in various aspects of antibody manufacturing, including production monitoring, quality control, commercial lot release, and stability testing.

ДОСЛІДЖЕННЯ ГІДРОЛІТИЧНОЇ ДЕГРАДАЦІЇ ПОЛІГІДРОКСІАЛКАНОАТІВ І ЇХ СУМІШЕЙ З ПОЛІЛАКТИДАМИ

The hydrolytic degradation of polyhydroxyalkanoates, polylactide and their mixtures in vitro in physiological solution and phosphate-salt buffer as well was researched. The hydrolysis intensity of biopolymers was evaluated via the mass loss, change in molecular weight as well as the water absorption applying the methods of infrared spectroscopy and complex thermal analysis. It was determined that films based on the researched biodegradable polymers thermostated in a phosphate-salt buffer have been degrading faster than in physiological solution.