Increase In Tg Research Articles

Polyurethane adhesives from castor oil and modified lignin via reaction with propylene carbonate

AbstractOver the last several years, lignin hydroxypropylation with propylene oxide (PO) has been used as the main strategy to overcome lignin limitations, such as its low reactivity, poor dispersion, and high stiffness, in the context of polyurethane (PU) synthesis. However, PO is a flammable, toxic, and carcinogenic compound. Propylene carbonate (PC), a compound with low toxicity and biodegradability, has emerged as a feasible alternative to PO. Although this compound has potential for use in syntheses, lignin hydroxypropylation with PC has not yet been explored in PU synthesis. In this work, PU adhesives are synthesized using castor oil (CO) and hydroxypropylated lignin via the reaction with PC (HKL_PC) as a polyol. HKL_PC is incorporated in CO at different concentrations (10 wt%, 20 wt%, and 30 wt%). Curing kinetics is investigated with temperature‐modulated optical refractometry (TMOR). Dynamic mechanical analysis (DMA) demonstrates an increase in Tg after lignin addition. Furthermore, Young's modulus and practical adhesion are improved with increasing HKL_PC concentration. Results prove that hydroxypropylation with PC is a feasible method for lignin‐based PU synthesis and reveals the potential of this approach as an alternative for the PO‐based method.

Active Composite Packaging Reinforced with Nisin-Loaded Nano-Vesicles for Extended Shelf Life of Chicken Breast Filets and Cheese Slices.

To meet the demands for more effective and ecofriendly food packaging strategies, the potential of nisin-loaded rhamnolipid functionalized nanofillers (rhamnosomes) has been explored after embedding in hydroxypropyl-methylcellulose (HPMC) and κ-carrageenan (κ-CR)-based packaging films. It was observed that intrinsically active rhamnosomes based nanofillers greatly improved the mechanical and optical properties of nano-active packaging (NAP) films. Incorporation of rhamnosomes resulted in higher tensile strength (5.16 ± 0.06 MPa), Young’s modulus (2777 ± 0.77 MPa), and elongation (2.58 ± 0.03%) for NAP than active packaging containing free nisin (2.96 ± 0.03 MPa, 1107 ± 0.67 MPa, 1.48 ± 0.06%, respectively). NAP demonstrated a homogenous distribution of nanofillers in the biopolymer matrix as elucidated by scanning electron microscopy (SEM). Thermogravimetric analysis (TGA) confirmed that NAP prepared with nisin-loaded rhamnosomes was thermally stable even above 200 °C. Differential scanning calorimetry (DSC) analyses revealed that addition of nisin in nanofillers resulted in a slight increase in Tg (108.40 °C), indicating thermal stability of NAP. Fourier transform infrared spectroscopy (FTIR) revealed slight shift in all characteristic bands of nano-active packaging, which indicated the embedding of rhamnosomes inside the polymer network without any chemical interaction. Finally, when tested on chicken breast filets and cheese slices under refrigerated storage conditions, NAP demonstrated broad-spectrum antimicrobial activity (up to 4.5 log unit reduction) and inhibited the growth of Listeria monocytogenes, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. These results suggest that HPMC and κ-CR-based NAP containing functionalized nanofillers can serve as an innovative packaging material for the food industry to improve the safety, quality, and shelf-life of dairy and meat products.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11947-022-02815-2.

UV protective bio-based epoxy/carbon quantum dots nanocomposite coatings: Synthesis and investigation of properties

This research focuses on synthesis and study of the properties of castor oil-based epoxy/carbon quantum dots (COEp/CQDs) nanocomposite coatings possessing resistance against UV. First, CQDs were synthesized by pyrolysis of starch using microwave-assisted method and characterized via various spectroscopic and microscopic methods. Next, certain quantity of castor oil as a renewable resource, CQDs with different weight percentages and a curing agent were added to epoxy resin and consequently COEp/CQDs were prepared. Through findings of FTIR, photoluminescence and UV-visible spectroscopy analyses, existent functional groups and fluorescent feature of the nanocomposite coatings were confirmed. UV-vis spectroscopy approved UV resistance of the COEp/CQDs coatings. As concentration of CQDs increased in resin matrix, UV absorption was maximized. The morphology and uniform dispersion of CQDs in the coatings matrix were verified by FESEM analysis. Results of TGA, pull-off adhesion strength and tensile tests, and DMTA analysis proved adding CQDs to the resin matrix led to progress of thermal endurance, adhesion strength, mechanical and viscoelastic properties of the synthesized coatings including an increase in storage modulus and Tg.

Potential Value of Serum Lipid in the Identication of Postoperative Delirium Undergoing Knee/Hip Arthroplasty: The Perioperative Neurocognitive Disorder and Biomarker Lifestyle Study.

ObjectiveWe aimed to investigate the relationship between preoperative lipid level and postoperative delirium (POD) and explore whether lipid’s effect on POD is mediated by POD core protein.MethodsA total of 635 patients who were planned to undergo knee/hip arthroplasty under combined spinal-epidural anesthesia, regardless of gender, were selected. The patients were aged 40–90 years with American Society of Anesthesiologists physical status I II. The Mini-Mental State Examination (MMSE) was completed 1 day before the operation. Five milliliter elbow venous blood was taken from the patients before anesthesia, and serum levels of total cholesterol (TG), triglyceride (TC), low-density lipoprotein (LDL-C), and high-density lipoprotein (HDL-C) were detected. Cerebrospinal fluid (CSF) was extracted after successful spinal-epidural combined puncture, and amyloid beta40 (Aβ40), amyloid beta42 (Aβ42), total Tau (t-Tau), and phosphorylated Tau (p-Tau) in the CSF were measured by enzyme-linked immunosorbent assays (ELISA). After the operation, the occurrence and severity of POD were assessed using the Confusion Assessment Method and the Memorial Delirium Assessment Scale (MDAS), respectively. Patients were categorized into POD group and NPOD group. Logistic regression was used to analyze the relationship between POD and TC, TG, LDL-C, and HDL-C, and the mediating effect was used to analyze the role of POD core proteins in the relationship between lipid and MDAS. We used the receiver operating characteristic (ROC) and the precision-recall curve (PRC) analysis to assess the ability of TC, TG, LDL-C, and HDL-C ability to predict POD. Finally, we performed a sensitivity analysis to assess the stability of the results.ResultsA total of 562 patients were finally enrolled in this study, and 66 patients developed POD, with an incidence of 11.7%. Logistic regression analysis showed that high concentration of TC (OR = 3.148, 95%CI 1.858∼5.333, P < 0.001), TG (OR = 2.483, 95%CI 1.573∼3.918, P < 0.001), and LDL-C (OR = 2.469, 95%CI 1.310∼4.656, P = 0.005) in serum were risk factors for POD. A high concentration of HDL-C (OR = 0.258, 95%CI 0.112∼0.594, P = 0.001) was a protective factor for POD after adjusted for age, sex, education, and MMSE score. ROC curves showed that HDL-C have the highest sensitivity and specificity in predicting POD. For these four lipid markers, the PRC range from 0.602 to 0.731, respectively. The mediating analysis showed that POD core proteins could partially mediate the relationship between lipid and POD (effect value: 16.19∼91.04%). The results were barely changed in the sensitivity analysis, and the sensitivity analysis has shown that the results were stable.ConclusionThe increase of serum TG, TC, and LDL-C concentration is a risk factor for POD development, while high HDL-C concentration is a protective factor for POD, and the occurrence of POD is caused by hyperlipidemia may be caused by POD core proteins.Clinical Trial Registration[www.ClinicalTrials.gov], identifier [Chictr200033439].

Lipid profile of the ethanol - methanol (1:1) extracts of Anacadium occidentale and Jatropha tanjorensis administration in Wistar rats

Hyperlipidaemia is characterized by an increase in one or more of the plasma lipids. This study evaluated the lipid profile of albino Wistar rats administered ethanol-methanol extracts of Anacadium occidentale and Jatropha tanjorensis leaves. Twenty-five (25) male Wistar rats weighing between 180 - 220 g were divided into five (5) groups of five (5) rats each and treated thus: Group 1 (normal control received normal saline), group 2 and 3 administered low dose (400 mg/kg-1 b.wt.) and high dose (800 mg/kg-1 b.wt.) of Anacadium occidentale extract respectively, group 4 and 5 administered low dose (400 mg/kg-1 b.wt.) and high dose (800 mg/kg-1 b.wt.) of Jatropha tanjorensis extract respectively. At the end of the experiment, the rats were sacrificed to obtain the sera for the evaluation of serum lipid profile. The result revealed a significant (P&lt;0.05) decrease in TC in all the groups except group IV compared with control. There was a significant (P&lt;0.05) increase in TG and VLDL-c levels in all groups compared with control. HDL-c level significantly (P&lt;0.05) increased in group III only compared with control. LDL-c level significantly (P&lt;0.05) decreased in group III and V only compared with control. The LDL-c/HDL-c ratio showed no significant (P0.05) difference between groups II, V and control, however group III significantly (P&lt;0.05) decreased and group IV significantly (P&lt;0.05)increased compared with the rest groups. The study suggests that the plant extracts possess lipid lowering potentials and may be employed in the treatment of metabolic disorders such as obesity and cardiovascular diseases.

Flame Propagation Characteristics in the Boundary Layer of the Bio-Water-Coal Fuel Particle During its Ignition

ABSTRACT The article presents the experimental research results of the flame propagation processes in the small vicinity of Bio-WCF particles during their ignition. According to the experimental researches, there have been obtained characteristic ignition delay times (tign) and times of full engulfment of the fuel particle in fire (tsf). We have analyzed the influence of metamorphism degree of fuel basic component (coal) and sort of biomass on characteristics of these processes. It has been shown that increase in concentration of biomass in fuel leads to decrease in ignition delay times and fire propagation in boundary layer of the Bio-WCF particle. We have recognized that the oxidizer temperature (Tg) strongly influences the fire propagation dynamic in small volume vicinity of fuel particles. Also, we have observed that the effect of influence of oxidizer temperature (Tg) on the time of full engulfment of the fuel particle in fire (tsf) differs from the predicted once. Increase in Tg in a certain period of changes in its values (Tg = 1073–1273 K) leads to increase in time of full engulfment of the Bio-WCF particle in fire. The hypothesis describes the influence of ambient temperature on tsf was formulated. We have substantiated the hypothesis using the results of mathematical modeling. This hypothesis describes the physical mechanism of the influence of water vapors, which are formed during intrapore moisture evaporation on characteristics and conditions of volatile combustion in the boundary layer of the fuel particle.

Influence of polybenzimidazole nanoparticle on the thermo-mechanical characteristics of high density polyethylene composite

This present research focuses on the mechanical, thermal, flammability and thermo-mechanical behavior of varying percentages of high performance polymer polybenzimidazole (PBI) nanoparticle reinforced high density polyethylene (HDPE) composite. The principal aim of this present study was to investigate how the addition of polybenzimidazole nanoparticle influences the mechanical, thermal, flammability and thermo-mechanical behavior of high density polyethylene thermoplastic composite. The composites of polyethylene and polybenzimidazole were prepared by a melt intercalation process with different weight proportions as 1, 3 and 5 wt% using a twin-screw extruder. The prepared composites were characterized for their properties in-accordance to ASTM standards. The mechanical properties revealed significant improvements for PBI addition. The Scanning Electron Microscope (SEM) fractograph revealed moderate waviness and improved toughness. Similarly, the results of Thermo gravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) showed an increase in Tg and mass loss stability for 5 wt% of PBI. The Flammability and Dynamic mechanical analysis (DMA) results showed an increased flame resistance, damping and loss modulus for high concentration of PBI nanoparticle. These mechanically, thermally and thermo-mechanically toughened HDPE thermoplastic composites could be used in engineering, space, wearable material and defence applications where high toughness, high thermal stability structural materials are required.

Glass formation and properties of the TeO2-ZnO-BaO tellurite optical glasses

We report the thorough study on glass forming ability and properties of the TeO2-ZnO-BaO (TZB) optical glasses prepared by the melt-quenching method at 900 °C. The attention has been paid to investigation of thermal, structural, and optical properties of glasses with content of TeO2 from 52.5 up to 90%. The introduction of ZnO and/or BaO into TeO2-based glass results in increase of the glass transition temperature Tg from 319 to 369 °C and decrease of the refractive index and density of prepared glasses. The structure of studied TZB glasses was investigated by Raman scattering. Since the TZB glasses exhibit good thermal stability, wide spectral region of transparency from ultraviolet (UV), λ ≈ 0.35 μm, up to mid-infrared (MIR), λ ≈ 6 μm, wavelengths with high values of refractive index (n1550 ≈ 1.87–2.04), they may be utilized as optical materials, which can be designed on the results presented in this paper.

Formation and crystal growth of needle-like rutile in glass- ceramics

Glass-ceramic, which has negligible dielectric loss, high mechanical strength, excellent drop resistance, low CTE, and low density for lightweight design, is the best option for the back cover of mobile devices in the 5 G era. Herein, the effect of P2O5 on the phase separation and crystallization of MgO–Al2O3–SiO2-TiO2 glass-ceramics is studied. The incorporation of P2O5 in the glass structure leads to phase separation, in which the P and Mg-enriched phase was formed in the glass matrix, and promotes the increase of Tg. With the increase of P2O5 content, the precipitated crystals change significantly. First, the silicate crystals (Mg2SiO4) disappear, whereas the phosphate crystals (LiMgPO4) emerge when 2 mol% P2O5 is introduced. Second, titanate crystal (MgTi2O5) can not be observed when 4 mol% P2O5 is introduced. The Ti5O9 crystals appear simultaneously with LiMgPO4 crystals and transform to rutile TiO2 crystals at high temperature. Interestingly, the needle-like rutile TiO2 crystals, which is 300 nm long and 20 nm wide, have been found in a glass with 4 mol% P2O5. The large L/D ratio of needle-like crystals increases the hardness significantly from 6.08 GPa to 7.14 GPa. Similar to other fiber reinforced composites, this needle-like crystals provide a new strategy to improve the mechanical properties of glass ceramics.

Enhanced Glass Transition Temperature of Thin Polystyrene Films Having an Underneath Cross-Linked Layer.

Due to the importance of the interface in the segmental dynamics of supported macromolecule ultrathin films, the glass transition temperature (Tg) of polystyrene (PS) ultrathin films upon solid substrates modified with a cross-linked PS (CLPS) layer has been investigated. The results showed that the Tg of the thin PS films on a silica surface with a ∼5 nm cross-linked layer increased with reducing film thickness. Meanwhile, the increase in Tg of the thin PS films became more pronounced with increasing the cross-linking density of the layer. For example, a 20 nm thick PS film supported on CLPS with 1.8 kDa of cross-linking degree exhibited a ∼35 and ∼50 K increase in Tg compared to its bulk and that on neat SiO2 substrate, respectively. Such a large Tg elevation for the ultrathin PS films was attributed to the interfacial aggregation states in which chains diffused through nanolevel voids formed in the cross-linked layer to the SiO2-Si surface. In such a situation, the chains were topologically constrained in the cross-linked layer with less mobility. These results offer us the opportunity to tailor interfacial effects by changing the degree of cross-linking, which has great potential application in many polymer nanocomposites.

The quality control assessment of cyanate ester blend (EX-1515) resin based composites concerning hydrolysis

Cyanate ester resins are essential matrix materials for advanced composites demanding excellent mechanical properties and dimensional stability under varying hygrothermal and radiative environments. However, a critical processing complication arises due to moisture sensitivity during cure which compromizes mechanical and thermal properties. Therefore, a reliable evaluation technique is necessary to ensure the successful use of cyanate ester-based composites. In this report, quality control (QC) signatures of a cyanate ester blend (EX-1515) are evaluated in comparison to those of an unmodified single-component cyanate ester resin (RS3C). Varying degrees of EX-1515 hydrolysis, i.e., carbamate formation, were investigated via FTIR and correlated to decreases in glass transition temperature by DSC and changes in the thermal decomposition profile by TGA. Also flatwise tension (FWT) strengths were observed to decrease with increasing hydrolysis. These results on as-cured EX-1515 were analogous to what was previously reported on RS3C. However, with elevated thermal post-treatments, their thermomechanical properties displayed an opposite trend; While hydrolyzed RS3C exhibited even further progressive reductions in Tg with a post-cure, EX-1515 showed significant increases, likely due to a new polymerization reaction involving carbamates and additional chemical moieties in the blend formulation. Interestingly, the post-cure Tg increase did not translate to any improvement in mechanical properties. On the contrary, the strength showed a dramatic reduction due to thermal degradation of the hydrolysis by-products resulting in increased porosity. The QC signatures of EX-1515 proved to be more complex than RS3C. Therefore, it is necessary to consider multiple QC signatures with carefully chosen thermal treatments rather than relying on a single point Tg measurement without the full thermal history information of the cyanate ester material.

Гендерные и возрастные особенности связи антропометрических параметров ожирения с нарушениями липидного обмена

Гендерные и возрастные особенности связи антропометрических параметров ожирения с нарушениями липидного обмена

Biocompatible thermoresponsive N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide-based random copolymer: synthesis and studies of its composition dependent properties and anticancer drug delivery efficiency.

A new acrylamide monomer, N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide (M3i), consisting of both isopropyl and isopropylamidopropyl moieties, has been synthesized from isopropylamine and N-isopropylacrylamide via an aza-Michael addition reaction followed by amidation with acryloyl chloride. The homopolymer of M3i (polyM3i) and a series of random copolymers of M3i and poly(ethylene glycol)methyl ether acrylate (PEGA: CH2CHCO2(CH2CH2O)nMe, Mn = 480, n = 9 on average) with varying compositions have been synthesized via reversible addition-fragmentation chain transfer polymerization using 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) as well as 1-phenylethyl phenyl dithioacetate (PEPD) as a RAFT agent. These polymers have been characterized by 1H NMR, FTIR, GPC, UV-Vis, fluorescence, TGDTA, DSC, DLS, and TEM techniques. A lower critical solution temperature (LCST) and glass transition temperature (Tg) for polyM3i prepared using DDMAT were observed at 17 and 133 °C, respectively, while for a polymer formed using PEPD, no LCST was observed until 0 °C and its observed Tg was found at 127.3 °C. The polymers are thermally stable up to 300 °C. Upon an increase in the M3i content in the copolymers, LCST decreases, Tg increases, and the apparent hydrodynamic diameter decreases. Moreover, the effects of concentration and the addition of urea and sodium chloride on the LCST of the copolymer with an LCST close to body temperature were studied. Owing to the incorporation of PEGA, a higher critical micellar concentration and larger TEM particle size of this copolymer were observed with respect to those of polyM3i. The usefulness of the micelles of the copolymers as nano-carriers for the drug doxorubicin was explored. The in vitro tumoricidal activity of the micelles of the doxorubicin-loaded copolymers was also assessed against Dalton's lymphoma cells.

Potential Effects of Boldine on Oxidative Stress, Apoptosis, and Inflammatory Changes Induced by the Methylprednisolone Hepatotoxicity in Male Wistar Rats.

BackgroundSynthetic glucocorticoid therapeutic agent methylprednisolone (MPL), when used for an extended period of time at high dose, promotes the development of reactive oxygen species (ROS)-induced liver toxicity. This study investigated the role of boldine, a natural antioxidant with anti-apoptotic and anti-inflammatory properties, against MPL-induced hepatoxicity in male Wistar rats.Methods120 rats were divided into eight equal groups: G1 (control), G2, 3, and 4 (rats orally administered 5, 10, and 50 mg boldine/kg b.w./day; respectively, for 28 days), G5 (rats intramuscularly injected with 100 mg MPL/kg b.w. only on the last three days), G6, 7, and 8 (rats administered boldine + MPL). After the last MPL injection, rats were sacrificed at intervals of 1, 24, and 48 h.ResultsThere was a significant decrease in WBCs, RBCs count, and HGB levels, as well as an increase in PLT count, ALT, AST, TG, and LDL levels, and a decrease in HDL level in serum. Oxidative stress markers levels increased at all times, and gene expression of antioxidant enzymes increased at 24h. Immunohistochemical analysis revealed that cytochrome c levels significantly increased after MPL treatment. The COMET assay revealed detectable DNA lesions. There was no immune reactivity of IL-6 expressions as an inflammatory response marker.ConclusionsOral administration of boldine has a modulatory protective, antioxidant, and anti-apoptotic effect against free radicals.

Association of Hyperlipidemia in Second Trimester of Pregnancy with Maternal and Neonatal Outcomes

Introduction: Pregnancy is a state of metabolic stress associated with high lipid levels; the highest concentration observed during third trimester. The imbalance in the amount of lipidshas been related to maternal-perinatal pathologies such as preeclampsia (PE), gestational diabetes mellitus (GDM) and preterm birth. Aim/Objectives: Our study was aimed at studying the association of serum lipid profile during second trimester with the various adverse pregnancy outcomes. Methods: A cohort of 150 antenatal mothers were recruited and were evaluated for serum lipid profile during the second trimester. They were followed up till delivery and maternal and neonatal outcome, were recorded. Conclusion: It was concluded that there were direct implications of dyslipidemia on maternal and perinatal outcomes. Increase in maternal TG, TC, LDL and VLDL concentrations were the most important changes affecting maternal outcomes and had significant association with GDM, PE and PTB. HDL did not have any association with any adverse maternal or neonatal outcome.

دراسة تأثير الكايتوسان المستخلص من فطر العرهون على فرط الدهون المستحث تجريبا في ذكور الأرانب

The present study aimed to identify the therapeutic evaluation of chitosan extracted from the fungus cushroom and pure chitosan on glucose and lipid profile in the blood of 35 male rabbits with hyperlipidemia induced experimentally by cholesterol. The tests included estimation of glucose levels, total cholesterol, triglycerides, high-density lipoproteins, low-density lipoproteins, and very low-density lipoproteins. hyperlipidemia was induced in the male rabbits used in the study which was administered orally with cholesterol 150mg/kg body weight for a week. rabbits were divided into seven groups: control, cholesterol, pure chitosan, mushroom chitosan, cholesterol and pure chitosan, cholesterol and mushroom chitosan and cholesterol and simvastatin. The results of the study showed, the hyperlipidemia induced experimentally resulted a significant increase (P&lt;0.05) in TC, TG, LDL, and VLDL, while no significant difference in HDL compared with control group, on the otherwise the glucose level significantly increase than control. Also, groups of animals treatment with pure chitosan and mushroom chitosan showed a significant decrease (P&lt;0.05) in glucose, TC, TG, LDL, and VLDL, and no significant difference in HDL compared with control group. While, the groups showed treatment with cholesterol and pure chitosan, cholesterol and mushroom chitosan, cholesterol and simvastatin a significant decrease (P&lt;0.05) in glucose, TC, TG, LDL, and VLDL, and a significant increase (P&lt;0.05) in HDL compared with the cholesterol group. The research study revealed that chitosan extracted from mushroom can control the levels of fat concentrations and their complications, in addition to its important role in biochemical variables, and treatment of most disease cases, especially cardiovascular disease.

Relationship between Vitamin D Status, Dyslipaedemia and Antioxidant Status in Children with Idiopathic Nephrotic Syndrome in South West, Nigeria

Dysregulated lipid metabolism and oxidative stress are strong factors that are implicated in the development of proteinuria and glomerular injury in Nephrotic Syndrome (NS). Vitamin D seems to be a promising tool in influencing lipid metabolism and antioxidant status in NS.&#x0D; Aim: This study aims at investigating the relationship between Vitamin D, dyslipaedemia and oxidative stress in NS.&#x0D; Study Design: This is a case-control study.&#x0D; Place and Duration of Study: Children’s Outpatient Clinic (CHOP) of University College Hospital (UCH) Ibadan, Nigeria between year 2019-2021.&#x0D; Methods: This study involves fifty children aged 5 to 12 years, freshly diagnosed with Idiopathic NS and fifty apparently healthy children as control. Blood samples were taken from them and analytes quantified by standard laboratory methods. Students’ t test and Pearson correlation were used to compare variables between the two groups respectively.&#x0D; Results: Results showed significant decrease (P &lt;.001) in Vit. D levels, GPX, SOD and CAT in NS. A significant decrease (P&lt;.001) occurred in HDL, a significant increase (P &lt;.001) in TG, TC and LDL levels in children with NS when compared with the control. There was a strong significant positive relationship between Catalase and Vit. D, SOD and Vit. D (r= 0.896, 0.869 respectively, P&lt;.001) in NS. While a weak non significant positive relationship occurred between HDL and Vit. D, GPX and Vit D (r=0.0585, 0.0236 respectively, P &gt;.001). A weak negative relationship occurred between TG and Vit. D, TC and Vit. D, LDL and Vit. D (r=-0.0432,-0.219, -0.231 respectively, P&gt;.001), in NS. Thus, vitamin D insufficiency influences serum lipid profiles and antioxidants in paediatric Idiopathic NS.

Synthesis and investigation of structural, thermal, magnetic, and dielectric properties of multifunctional epoxy/Li0.5Al0.35Fe2.15O4/Al2O3 nanocomposites

Until recently, multifunctional epoxy nanocomposites (MENCs) have attracted the attention of many researchers due to their properties which can be tuned for the desired application. For high-frequency microelectronic and optoelectronic device packaging, materials with low dielectric permittivity, low dielectric losses, high dielectric strength, and high thermal conductivity have been required. Toward this goal, epoxy/Li0.5Al0.35Fe2.15O4/Al2O3 (wt.%: (95:5-y:y): y ranges from 1 to 5 wt.% by steps of 1 wt.%) nanocomposites were prepared and investigated. The nanocomposite samples were characterized by X-ray diffraction, FT-IR spectroscopy, transmission electron microscope, scanning electron microscope, and thermogravimetric analyzer. In the present study, the thermal conductivity of the samples is enhanced in the direction of increasing the Al2O3 nanofillers, contrary to the thermal stability. The sigmoid M−H curves of the samples reveal their soft ferrimagnetic nature. As the nonmagnetic Al2O3 nanofillers content increases, the magnetic parameters Ms, Mr, and Ls decrease, while Hc and Sq increase with the magnetic anisotropy increase. The interesting results of decreasing σʹac, ε′, and tanδ for the composite samples of y = 1 to 4 wt.% to values below the unfilled epoxy sample are explained depending on the dual interface nanolayer model (DINM). Also, based on the DINM, the increase of Tg and dielectric strength for the same samples is interpreted.

Review of Recent Developments of Glass Transition in PVC Nanocomposites.

This review addresses the impact of different nanoadditives on the glass transition temperature (Tg) of polyvinyl chloride (PVC), which is a widely used industrial polymer. The relatively high Tg limits its temperature-dependent applications. The objective of the review is to present the state-of-the-art knowledge on the influence of nanofillers of various origins and dimensions on the Tg of the PVC. The Tg variations induced by added nanofillers can be probed mostly by such experimental techniques as thermomechanical analysis (TMA), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and dielectric thermal analysis (DETA). The increase in Tg is commonly associated with the use of mineral and carbonaceous nanofillers. In this case, a rise in the concentration of nanoadditives leads to an increase in the Tg due to a restraint of the PVC macromolecular chain’s mobility. The lowering of Tg may be attributed to the well-known plasticizing effect, which is a consequence of the incorporation of oligomeric silsesquioxanes to the polymeric matrix. It has been well established that the variation in the Tg value depends also on the chemical modification of nanofillers and their incorporation into the PVC matrix. This review may be an inspiration for further investigation of nanofillers’ effect on the PVC glass transition temperature.

Effect of Eu3+ and Tb3+ ions concentration on the mechanical, structural, and photoluminescence properties of phosphate glass fibers

Two series of phosphate glasses belonging to the (65-x) P2O5–35CaO–xRE2O3 system (RE = Eu or Tb; 0 ≤ x ≤ 6 mol%) were prepared by the melt-quenching technique. All compositions were successfully drawn as continuous monofilaments fibers. The effect of Eu3+ and Tb3+ ions concentration on their mechanical, structural, and photoluminescence properties was investigated. The results revealed that the highest tensile strength was 1031 ± 34 MPa for fibers doped with 6 mol% of Eu2O3 and 1014 ± 65 MPa for fibers doped with 6 mol% of Tb2O3. The addition of RE2O3 showed an increase in density and Tg. A structural investigation was carried out using FTIR spectroscopy. The photoluminescence properties in terms of excitation and emission spectra were investigated in detail. The most intense emission band at 611 nm corresponds to the 5D0 → 7F2 transition of Eu3+ ions under 392 nm excitation was observed for fibers doped with 6 mol% of Eu2O3. The most intense emission band at 543 nm corresponds to the 5D4 → 7F5 transition of Tb3+ ions under 374 nm excitation was observed for fibers doped with 6 mol% of Tb2O3. These two compositions exhibited the highest absolute quantum yield, reaching 20.25% and 4.81%, respectively.