High Degree Of Polymerization Research Articles

Rheological properties of cross-linked inulin solutions as a function of cross-linker concentration and temperature

The purpose of this study is to determine the rheological properties of cross-linked inulin solutions in two different polymerization degrees (native and degree of polymerization of >23%). Thus, the effect of cross-linking, a new approach applied to support a specific property (stabilization) of inulin, which has many benefits, has been demonstrated. Sodium hexametaphosphate was used as a cross-linking agent at three different ratios (0.375%, 0.500%, and 0.750%). The cross-linked inulin solutions were lyophilized, and the lyophilized mixture was then reconstituted at 25 °C and 45 °C to obtain cross-linked inulin solutions with 1% and 5% (w/v) concentrations. The control samples (native and with a high degree of polymerization) were treated similarly without a cross-linking agent. The samples were subjected to a dynamic frequency sweep test in the range of 0.01–10 Hz as well as shear viscosity measurements at 1–500/s shear rates for the determination of rheological properties. The thixotropic curves were analyzed as the shear rate increased from 0.1/s to 300/s in the first 120 s (up curve), and then decreased to the same point in the subsequent 120 s. Results indicated that cross-linking increased inulin solution viscosity, particularly at 5% concentration, and solubility. Solutions with 5% inulin containing 0.750% and 0.375% cross-linker yielded the highest viscosities at 45 °C and 25 °C, respectively. Samples with 5% inulin concentration exhibited solid-like behavior in the oscillation test. Thixotropic curves revealed antithixotropy at low shear rates and thixotropy at high shear rates. The study demonstrated the impact of cross-linking on inulin stabilization, providing insights for future applications. Results indicated that cross-linking increased inulin solution viscosity, particularly at 5% concentration, and solubility. Solutions with 5% inulin containing 0.750% and 0.375% cross-linker yielded the highest viscosities at 45 °C and 25 °C, respectively. Samples with 5% inulin concentration exhibited solid-like behavior in the oscillation test. Thixotropic curves revealed antithixotropy at low shear rates and thixotropy at high shear rates. The study demonstrated the impact of cross-linking on inulin stabilization, providing insights for future applications.

Step-growth polymerization of supracolloidal chains from patchy micelles of diblock copolymers

HypothesisThe formation of supracolloidal chains from the patchy micelles of diblock copolymers bears a close resemblance to traditional step-growth polymerization of difunctional monomers in many aspects, including chain-length evolution, size distribution, and initial-concentration dependence. Thus, understanding the colloidal polymerization based on the step-growth mechanism can offer potential control over the formation of supracolloidal chains in terms of chain structure and reaction rate. ExperimentsWe analyzed the size evolution of supracolloidal chains of patchy micelles of PS-b-P4VP by investigating a large number of colloidal chains visualized in SEM images. We varied the initial concentration of patchy micelles to achieve a high degree of polymerization and a cyclic chain. To manipulate the polymerization rate, we also changed the ratio of water to DMF and adjusted the patch size by employing PS(25)-b-P4VP(7) and PS(145)-b-P4VP(40). FindingsWe confirmed the step-growth mechanism for the formation supracolloidal chains from patchy micelles of PS-b-P4VP. Based on this mechanism, we were able to achieve a high degree of polymerization early in the reaction by increasing the initial concentration and form cyclic chains by diluting the solution. We also accelerated colloidal polymerization by increasing the ratio of water to DMF in the solution and patch size by using PS-b-P4VP with a larger molecular weight.

STUDY OF THE RHEOLOGICAL AND PHYSICOCHEMICAL PROPERTIES OF FRUCTAN FRACTIONS OF Agave tequilana cv. cenizo

The physico-mechanical properties of fructan fractions in different agave species without Tequila Denomination of Origin (DOT) need to be studied to identify and expand industrial applications. The rheological and physicochemical characterization of three fractions of Agave tequilana cv. cenizo fructans without DOT, with different degree of polymerization (DP) was carried out to propose their use as an additive in the food industry. Fractions were obtained by apparent DP enrichment (DPa) by stepwise ultradiafiltration with 10, 5 and 1 kilodalton (kDa) membranes and classified on the basis of the enriched fraction evidenced by HPLC profiling with amperometric detector. The ultradiafiltrate of the membrane with 10 kDa, called High Degree of Polymerization (HDP), showed enrichment of fructans with high DPa ≥ 30, the one with 5 kDa called Intermediate Degree of Polymerization (IDP), presents enrichment in DPa between 10 to 30, these fractions dried by spray, showed a modal particle size distribution (D [4,3] < 20 µm). In the ultradiafiltrate of the 1 kDa membrane, called Low Polymerization Grade (LDP), fructo-oligosaccharides (FOS) and fructans with maximum DPa of 15 were enriched; this sample was concentrated to 72 °Brix. The glass transition (Tg) showed a DPa-dependent increase (LDP = 152.17 °C, IDP = 216.12 °C and HDP = 227.5 °C). Viscosity was dependent on the degree of polymerization, exhibiting thermo-mechanically stable flow behavior. The reconstituted powders exhibited Newtonian and flow-stable behavior in a concentration range of 2-50 %, temperature of 5-45 °C and pH of 2-9. The macro and micro structural properties identified in the respective fractions of agave fructans, diversify possible applications with potential interest as encapsulating material, stabilizer and prebiotic sweetener, among others that agave fructans have in the food and nutraceutical industry.

Three Polyborates with High-Symmetry [B12O24] Units Featuring Different Dimensions of Anion Groups.

Three polyborates, namely, LiNa11B28O48, Li1.45Na7.55B21O36, and Li2Na4Ca7Sr2B13O27F9, were synthesized via the high-temperature solution method. All of them feature high-symmetry [B12O24] units, yet their anion groups exhibit distinct dimensions. LiNa11B28O48 features a three-dimensional anionic structure of 3[B28O48]∞ framework, which is composed of three units: [B12O24], [B15O30], and [BO3]. Li1.45Na7.55B21O36 possesses a one-dimensional anionic structure of 1[B21O36]∞ chain consisting of [B12O24] and [B9O18] units. The anionic structure of Li2Na4Ca7Sr2B13O27F9 is composed of two zero-dimensional isolated units, namely, [B12O24] and [BO3]. The novel FBBs [B15O30] and [B21O39] are present in LiNa11B28O48 and Li1.45Na7.55B21O36, respectively. The anionic groups in these compounds exhibit a high degree of polymerization, thereby augmenting the structural diversity of borates. And the crystal structure, synthesis, thermal stability, and optical properties were meticulously discussed to guide the synthesis and characterization of novel polyborates.

Date seeds (Phoenix dactylifera): antioxidant potential and profile of free and bound polyphenols fromdifferent cultivars.

In this study, the antioxidant activities and detailed phenolic profiling of extracts from seven cultivars of date seeds were investigated. Significant differences were detected among cultivars. Total phenolic content (TP) ranged between 135.9±12.1 and 284.86±21.9 mg GAE/g DM. The total flavonoid value varied between 34.20±0.34 and 94.46±1.04 mg RE/g DM. The condensed tannin ranged from 24.17±1.13 to 201.60±9.95 mg CTE/g DM. Phloroglucinolysis was used to depolymerize the bound polyphenols. Results show the presence of phenolic acids: Hydroxybenzoic acid, hydroxycinnamic acid, and a high amount of flavan-3ols (monomers, dimers, and trimers). Before depolymerization, the highest amount of total polyphenols was identified in Kenta (8.48 g/kg) and the lowest was detected in Hessa (4.74 g/kg). After depolymerization, the flavan-3-ols increased significantly, ranging between 46.91g/kg in Hessa and 72.38 g/kg in Deglet Nour, with a high degree of polymerization (DP) in all cultivars. It can be concluded that date seeds represent a good source of bioactive compounds.

Effects of Dietary Protein and Lipid Levels on Growth, Metabolism, Antioxidative Capacity, and Fillet Quality of Adult Triploid Rainbow Trout Farmed in Net Cage.

The research is aimed at investigating the effects of dietary protein and lipid levels on adult triploid rainbow trout growth performance, feed utilization, digestive and metabolic enzyme activities, antioxidative capacity, and fillet quality. Nine diets containing three dietary protein levels (DP) (300, 350, and 400 g kg-1) and three dietary lipid levels (DL) (200, 250, and 300 g kg-1) were prepared using a 3 × 3 factorial design. In freshwater cages, 13,500 adult female triploid rainbow trout (3.2 ± 0.1 kg) were cultured for 77 days. Triplicate cages (500 fish per cage) were used as repetitions of each experimental diet. The findings revealed that as DP increased to 400 g kg-1 and DL raised to 300 g kg-1, the weight gain ratio (WGR) elevated significantly (P < 0.05). However, when DP ≥ 350 g kg-1, WGR was similar in the DL250 and DL300 groups. As DP raised to 350 g kg-1, the feed conversion ratio (FCR) notably decreased (P < 0.05). In the DP350DL300 group, lipids had a protein-sparing impact. High DP diet (400 g kg-1) generally improved fish health status by increasing antioxidant capacity in the liver and intestine. A high DL diet (300 g kg-1) showed no harmful effect on hepatic health based on plasma levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and antioxidant capacity in the liver. For fillet quality, a high DP diet could increase fillet yield, improve fillet hardness, springiness, and water-holding capacity values, and inhibit the production of off-flavors caused by n-6 fatty acids. A high DL diet could increase odor intensity, and EPA, DHA, and n-3 fatty acid concentrations decrease the thrombogenicity index value. The maximum fillet redness value was discovered in the DP400DL300 group. Overall, for adult triploid rainbow trout (≥3 kg), the minimum recommended DP and DL according to growth performance were 400 and 250 g kg-1, respectively; DP and DL based on feed utilization were 350 and 200 g kg-1, respectively; DP and DL based on fillet quality were 400 and 300 g kg-1, respectively.

Inulin extraction from Stevia rebaudiana roots in an autoclave

Inulin is a polymer of d-fructose, characterized by the presence of a terminal glucose, and are a major component of Stevia rebaudiana roots. This type of polymer has nutritional properties and technological applications, such as fat substitutes in low-calorie foods and as the coating of pharmaceuticals. The aim of this study was to evaluate an alternative method for inulin extraction, in terms of extraction time and yield, since the traditional method of extraction under reflux is both time and energy consuming. Using the response surface methodology (RSM) with Box-Behnken design it was observed that the alternative extraction method using autoclave presented similar yields to the reflux-based method, but with a shorter extraction time, 121 °C by 17.41 min 1H Nuclear Magnetic Resonance and Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-ToF-MS) analysis showed that inulin crude extract from S. rebaudiana roots obtained by autoclave extraction had a higher degree of polymerization when compared to those obtained by the traditional method. Thus, it is concluded that the proposed method using an autoclave is a faster alternative for the extraction of inulin.

Preparation and characterization of high strength and high modulus PVA-La fiber with synthesized syndiotacticity-rich high polymerization degree PVA polymers as raw materials

Preparation and characterization of high strength and high modulus PVA-La fiber with synthesized syndiotacticity-rich high polymerization degree PVA polymers as raw materials

Sequential Modification Strategy to Construct Crystalline Benzimidazole Covalent Organic Frameworks with Extraordinary Stability and Polymerization Degree

The intriguing proton-conducting and catalytic properties of benzimidazole-functionalized covalent organic frameworks (BIM-COFs) largely depend on their material quality. Here, we report a novel sequential modification (SM) strategy that enables the preparation of extraordinarily stable BIM-COFs with high polymerization degree. As a “proof of principle”, the designed TpBD-BIMSM was successfully synthesized using the SM strategy, which exhibited superior chemical stability (slight structural change after treatment in 6 M HCl or 6 M NaOH). Compared with the counterpart produced by the conventional direct condensation approach (TpBD-BIMDC), TpBD-BIMSM exhibited a higher Brunauer–Emmett–Teller (BET) surface area (213 m2 g–1 vs 52 m2 g–1) and significantly enhanced CO2, CH4, C2H6, and C2H4 uptake capacities. Furthermore, the proton conductivity of TpBD-BIMSM was measured to be 1.2 × 10–2 S cm–1, which is 2 orders of magnitude higher than that of TpBD-BIMDC (7.2 × 10–4 S cm–1) under identical conditions (80 °C and 98% RH) and also ranks it among the highest in all COF-based proton conductors. In addition, TpBD-BIMSM showed a lower activation energy (Ea) value than TpBD-BIMDC (0.16 eV vs 0.20 eV). Such high proton conductivity and low Ea value of TpBD-BIMSM can be attributed to its large surface area and high polymerization degree, which could provide extra proton transfer paths and accelerate proton movement. Furthermore, such a strategy can be readily extended to construct other BIM-COFs (TpOMe-BIMSM) that thus highlights the generality of sequential modification strategy. And this strategy thus paves a new way for constructing stable and highly polymerized BIM-COFs for related applications.

Production of Fructooligosaccharides Using a Commercial Heterologously Expressed Aspergillus sp. Fructosyltransferase

The catalytic properties of Seqenzym® FT, a fungal fructosyltransferase heterologously expressed in yeasts, were investigated at a temperature of 55 °C and pH 5.5. The initial rate measurements showed that the transfructosylation rate was only slightly inhibited by sucrose above the concentration of 1.5 M. A rather low level of hydrolytic side activity was observed even at sucrose concentrations as low as 0.25 M. In progress curve experiments, the mass yield of fructooligosaccharides (FOS) reached a maximum value of 57% at this sucrose concentration, although it dropped to about 35% later on. At high initial sucrose concentrations up to 2 M, the FOS yield reached a maximum value of approximately 63% at a sucrose conversion of approximately 90%. Although neither the yield nor the conversion changed much later on, the progress of the reaction was manifested by the gradual depletion of shorter chain FOS, 1-kestose and nystose, and the accumulation of 1-β-fructofuranosyl nystose. At initial sucrose concentrations of 2 M, the degree of polymerization expressed through the number of fructosyl units grew from 2.3 at a conversion degree of 87% to 3.1 at a conversion degree of 94%. Compared to other commercial preparations, Seqenzym® FT can better produce FOS with a higher degree of polymerization.

Effects of Plasticizing on Mechanical and Viscous Characteristics of Poly(vinyl alcohol): A Comparative Study between Glycerol and Diethanolamine

AbstractAlthough plasticizing materials by modification with small‐molecular chemicals has been extensively utilized in the industrial community, processing poly(vinyl alcohol) (PVA) at high concentrations (CPVA) or with a high degree of polymerization (DP) remains challenging. Optimization the plasticizing conditions is one means of addressing this issue. In this study, two types of frequently used plasticizers, glycerol (GLY) and diethanolamine (DEA), are chosen to plasticize PVA resin with a DP of 2400. Both PVA/plasticizer films possess excellent optical transmittance and mechanical ductility, whereas the films blended with DEA exhibit higher strength than the PVA/GLY films. The viscosity variation in the temperature (Top)–CPVA space is monitored by real‐time viscous flow testing, demonstrating that DEA is more effective for reducing the viscosity of PVA, which should improve the processability, facilitating film‐forming from concentrated solutions. Furthermore, density functional theory calculations and molecular dynamics simulations illustrate that the PVA/DEA system has a lower binding energy, longer hydrogen bond length, and higher isotropic diffusion coefficient, indicating a stable hydrogen bond network and homogenous dispersion of the plasticizer, leading to good solution fluidity and mechanical performance. This study is significant for guiding the design and manufacture of optically transparent, high‐performance PVA films as polarizer precursor.

Taste Detection of Maltooligosaccharides with Varying Degrees of Polymerization.

Previous studies have shown that humans can taste maltooligosaccharides [MOS; degree of polymerization (DP) of 3-20] but not maltopolysaccharides (MPS; DP of >20) and that their taste detection is independent of the canonical sweet taste receptor. The objectives of this study were to determine the DP ranges of target stimuli that are tasted and further to investigate the impact of DP on taste detectability. To achieve this goal, we prepared three food-grade MOS samples with narrow DP ranges using flash chromatography: low (4-6), medium (7-12), and high (14-21) DP samples. Following sample preparation, we asked subjects to discriminate the MOS stimuli from blanks after the stimuli were swabbed on the tip of tongue. All stimuli were initially presented at 75 mM. Acarbose, an α-glucosidase inhibitor, was added to all stimuli, including blanks, to prevent oral hydrolysis of MOS. After determining that all three MOS samples were detected at a significant degree, we conducted follow-up studies to explore whether the detection of these samples differed at a range of concentrations (18-56 mM). The results showed that detection rates of medium- and high-DP MOS varied in a concentration-dependent manner (p < 0.05). In contrast, low-DP MOS showed a consistent detection rate across concentrations tested. These results demonstrate that humans can taste MOS stimuli of all chain lengths and that relative taste detection rates are generally similar across MOS with varying chain lengths.

Multiscale kinetic modeling of biomass fractionation in an experiment: Understanding individual reaction mechanisms and cellulose degradation

To avoid over-consumption and wastage of virgin fibers, the quality of pulp products is as important as their productivity. To this end, both the quality and quantity of pulp should be considered together during the pulping processes. Multiple experimental studies have highlighted that maintaining a high degree of polymerization (DP) for cellulose microfibers in the wood chip ensures a good quality pulp product. However, in the pulping process, the applied reagents and severe conditions can cause a certain degree of cellulose degradation, accompanying unwanted lowering of fiber grades. In order to mitigate cellulose degradation during this step, it is crucial to control the process conditions such as reagent concentration and temperature. Also, to establish the optimum operating strategies, it is necessary to understand how the operating conditions impact the DP of cellulose microfibers. Therefore, we have proposed a novel multiscale model which predicts mesoscopic properties (e.g., the lignin content and fiber morphology) alongside microscopic properties (e.g., the DP of the cellulose microfibers). The proposed model incorporates a multi-layered kinetic Monte Carlo (kMC) framework that allows us to capture the temporal evolution of lignin content, fiber morphology, and cellulose DP, occurring at disparate timescales, as a function of reaction conditions in a computationally tractable fashion. Furthermore, the model predictions are validated with the experimental results so that it gives us a detailed picture of the pulp production processes. Overall with the proposed model, we aim to maximize productivity and maintain a high quality of cellulose fibers from the wood chips during the pulping process.

Selecting an appropriate binder to prepare alumina granules via spray freeze granulation drying

Spray freeze granulation drying (SFGD) is a granulation technique, involving the freezing of sprayed droplets, followed by freeze drying. This technique affords soft granules, which is advantageous for producing sintered bodies with few defects. However, non-spherical and/or hard granules are sometimes formed by SFGD, and the sintered body fabricated from such granules shows reduced density and strength. The formation of such non-spherical and/or hard granules is expected to be avoided by selecting an appropriate binder. Therefore, in this study, four types of binders (water-soluble acrylic polymer, acrylic emulsion, and poly vinyl alcohol with low and high degree of polymerization) were tested to produce alumina granules via SFGD. The shapes and properties of the granules, as well as densities and strength of the sintered bodies, were evaluated. By choosing a suitable binder, the formation of non-spherical granules can be significantly reduced, and soft granules are obtained. These leads to a sintered body with high density and high strength. The acrylic emulsion binder was found to be the best performing binder among the four binders.

Preparation and evaluation of injectable microsphere formulation for longer sustained release of donepezil.

In this study, donepezil-loaded PLGA and PLA microspheres (Dp-PLGA-M/Dp-PLA-M) and Dp-PLA-M wrapped in a polyethylene glycol-b-polycaprolactone (PC) hydrogel (Dp-PLA-M/PC) were prepared to reduce the dosing frequency of injections to treat Alzheimer's disease patients. Dp-PLGA-M and Dp-PLA-M with a uniform particle size distribution were repeatably fabricated in nearly quantitative yield and with high encapsulated Dp yields using an ultrasonic atomizer. The injectability and in vitro and in vivo Dp release, biodegradation, and inflammatory response elicited by the Dp-PLGA-M, Dp-PLA-M, and Dp-PLA-M/PC formulations were then compared. All injectable formulations showed good injectability with ease of injection, even flow, and no clogging using a syringe needle under 21-G. The injections required a force of <1N. According to the biodegradation rate of micro-CT, GPC and NMR analyses, the biodegradation of Dp-PLA-M was slower than that of Dp-PLGA-M, and the biodegradation rate of Dp-PLA-M/PC was also slower. In the Dp release experiment, Dp-PLA-M sustained Dp for longer compared with Dp-PLGA-M. Dp-PLA-M/PC exhibited a longer sustained release pattern of two months. In vivo bioavailability of Dp-PLA-M/PC was almost 1.4 times higher than that of Dp-PLA-M and 1.9 times higher than that of Dp-PLGA-M. The variations in the Dp release patterns of Dp-PLGA-M and Dp-PLA-M were explained by differences in the degradation rates of PLGA and PLA. The sustained release of Dp by Dp-PLA-M/PC was attributed to the fact that the PC hydrogel served as a wrapping matrix for Dp-PLA-M, which could slow down the biodegradation of PLA-M, thus delaying the release of Dp from Dp-PLA-M. Dp-PLGA-M induced a higher inflammatory response compared to Dp-PLA-M/PC, suggesting that the rapid degradation of PLGA triggered a strong inflammatory response. In conclusion, Dp-PLA-M/PC is a promising injectable Dp formulation that could be used to reduce the dosing frequency of Dp injections.

Identification of a Key Loop for Tuning Transglycosylation Activity in the Substrate-Binding Region of a Chitosanase.

Csn-PD, a glycoside family 46 chitosanase from Paenibacillus dendritiformis, exhibits endotype hydrolysis of chitosan and produces (GlcN)2 as the major product. Here, we report the crystal structure of Csn-PD at 1.68 Å resolution. The structure contains 14 α-helices and two β-strands that fold into two globular domains with the substrate bound between them. To evaluate the function of a loop in the substrate-binding region (residues 112-116, NDKHP), a mutant Csn-PDL1, in which this loop was deleted, was generated. Hydrolysis of chitosan by the mutant yielded chitooligosaccharides (COSs) with higher degrees of polymerization (DP) than the wild-type enzyme. Excitingly, (GlcN)6 was produced from smaller COSs via transglycosylation activity of the mutant. Hence, the catalytic performance of a chitosanase was altered by modification of a loop in the substrate-binding regions. Our novel data on a chitosanase with transglycosylation activity offer a promising way to produce COSs with high DP.

Evolution of Seed-Soluble and Insoluble Tannins during Grape Berry Maturation

Condensed tannins (CT) in wine are derived from the seeds and skins of grapes, and their composition and content contribute to the bitterness/astringency characteristics and ageing potential of the wine. Global warming has accelerated the ripening process of grape berries, making them out of sync with seed ripening. To understand the influence of berry ripening on the seed CT composition and content, we analyzed the changes in the soluble and insoluble CT in the seeds of 'Cabernet Sauvignon' grapes from two vineyards over two years. The results showed that the seed-soluble CT presented a slight downward trend in fluctuation during grape berry development, while the insoluble CT increased continuously before the véraison and remained at a high level afterwards. Relatively speaking, a lower sugar increment in developing grape berries favored the conversion of seed CT towards a higher degree of polymerization. The terminal unit of soluble CT was dominated by epigallocatechin gallate, the content of which decreased as the seeds matured. It is suggested that the seeds should be fully matured to reduce this bitter component in tannins. This study provides a reference for us to control the grape ripening process and produce high-quality grapes for wine making.

Burnout Syndrome and its Risk Factors among Gynecology Consultants

Background: Burnout as a condition characterised by emotional weariness, depersonalization (a propensity to show anti and cynical views about others) and a diminished feeling of personal success. In contrast to the more generalized concept of sadness, "burnout" describes a specific kind of fatigue that occurs in the job. Objective: The study's objectives were to (a) determine whether or not burnout (emotional exhaustion, depersonalization, and personal professional achievement) is influenced by environmental factors (gender, age, marital status, years of professional experience, number of hours worked per week, teaching level, workplace), and (b) determine whether or not these factors are related. Study Design: Cross sectional study Study Setting: This study was conducted at Department of Obstetrics and Gynecology Rashid Latif Medical College Lahore from July 2022 to December 2022. Methodology: By using a systematic random sample, we were able to include 60 gynecologists. The proforma was given to them through email or print mail, and they were contacted individually. Doctors were told that by completing the anonymous proforma, after taking their consents. The study's template has two sections. The participants' demographic information was found in the first document. The second section was a copy of the Maslach Burnout Inventory (MBI). The 22-item MBI is scored on a 0–6-point Likert scale. SPSS version 20 was used to analyze the data. Results: In all, 60 gynecologists filled the performa. Participants mean ages ranged 40.55 ±6.0 years. Forty-seven of the participants were female (78.3%), whereas just four were male 13 (21.7%). The vast majority of guys had their FCPS, while married people made up the bulk of the sample 38(63.3%). In addition, 48 people (80%) were chosen field of expertise. In this study, participants were classified as burnt out if they had high EE in addition to high DP or low PPA. Over a quarter of consultants were suffering from burnout. At least 33 people The burnout prevalence rate among doctors whose annual salaries fall between 60 and 100,000 PKR is disproportionately high (Table 2). Low-income physicians had more burnout than high-income physicians (p= 0.014).

Effect of Sodium Silicate on the Hydration of Alkali-Activated Copper-Nickel Slag Materials

This paper studied the influence of the modulus and dosage of sodium silicate on the hydration of alkali-activated copper-nickel slag (CNS) materials. CNS was used as the main raw material, and ground granulated blast furnace slag (GBFS) powder was selected as the mineral additive. The hydration and hardening mechanisms were discussed. The experimental results showed that [SiO4]4− and [AlO4]5− with a high degree of polymerization in the CNS glassy phase more easily underwent depolymerization-condensation and produced more C-S-H gels when the modulus was small and the sodium silicate dosage was high. When the content of sodium silicate was 7.0% and the modulus of sodium silicate solution was 1.0, the 28-day compressive strength of the material reached 125 MPa. This alkali-activated copper-nickel slag material can be used for mine filling, which has certain economic and ecological benefits.

Preparation of high‐strength, high‐modulus PVA fiber by synthesis of syndiotacticity‐rich high molecular weight PVA polymers with VAc and VBz via emulsifier‐free emulsion polymerization

AbstractDifferent vinyl acetate (VAc) and vinyl benzoate (VBz) monomer ratios have been chosen as monomers to create high polymerization degree (Pn) and high syndiotacticity‐diad content (S‐diad) poly(vinyl alcohol) (PVA) polymers via emulsifier‐free polymerization in order to address the problem of limited mechanical capabilities of PVA fibers prepared with low Pn and low S‐diad polymer. The variations in hydrogen bonding, Pn, S‐diad, and viscosity of different PVA polymers were investigated and evaluated using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, gel permeation chromatography, and a viscosity tester. Moreover, various PVA fibers with high strength and modulus have been manufactured using a synthetic polymer as the raw material for dry‐wet spinning. The effect of Pn and S‐diad on the mechanical and thermal characteristics of PVA fibers is evaluated using a variety of characterization techniques, such as the scanning electron microscope, differential scanning calorimetry, thermogravimetric analyzer, X‐ray diffraction, and tensile tester. As the ratio of VBz monomer increased, the results suggested that VBz may have a considerable impact on the Pn and S‐diad of PVA polymers, the OH vibration absorption peak reduced from 3491 to 3442 cm−1; the Pn increased from 2112 to 17,704; and the S‐diad rose from 51.2% to 60.1%. In addition to the fact that Pn and S‐diad significantly increased the fibers' strength and modulus, the crystallinity increased from 41.8% to 51.7%, and the orientation degree rose from 87.5% to 91.7%, as Pn and S‐diad increased; the tensile strength and highest elastic modulus increased from 9.71 ± 0.3 cN/dtex to 12.74 ± 0.5 cN/dtex (increased of 31.2%) and 264.52 ± 9.3 cN/dtex to 338.41 ± 8.6 cN/dtex (increased of 27.9%); the elongation at break decreased from 5.63 ± 0.3% to 2.92 ± 0.2%.