堇青石基玻璃陶瓷的制备与展望

介绍了制备堇青石基玻璃陶瓷的三种方法：熔融法、烧结法和溶胶-凝胶法，综述了玻璃组成、添加剂和成核剂对堇青石基玻璃陶瓷的烧结及性能的影响，并对其未来的发展进行了展望。     

Synthesis and Self-assembling Properties of 2,2′:6′,2″-Terpyridine-Based Carbon Nanotube Coordination Polymers

A novel metallo-supramolecular polytopic ligand was synthesized from the attachment reaction involving an amino group-functionalized multi-wall carbon nanotube and 4-chloro-2,2′:6′,2″-terpyridine used for the preparation of metallo-supramolecular polymers with Co(II) or Ni(II) ions. Different colors were observed depending on either the ligands or the metal ions in this type of supramolecular assembly. The created supramolecular polymers were characterized by means of structure, morphology, and stimuli-responsive performance employing scanning electron microscopy, amperometric techniques, UV–Vis and Fourier transform infrared spectroscopy. UV–Vis spectroscopy and cyclic voltammetry studies confirmed that both the optical and electrochemical properties of metallo-supramolecular materials are affected by the substituent at the pyridine periphery.     

Effect of conductive layer on the performance of gel electrolyte-based supercapacitors

Solid-state electrolytes such a further novel finding is going to have great importance because of the disadvantages of liquid electrolytes such as electrochemical instability, low ion selectivity, and interface contact. It is anticipated that the use of solid-state electrolytes including supercapacitors (SCs) will become widespread with decreasing self-leakage and environmental damage more than liquid electrolytes. In this study, SCs with graphene/PEDOT: PSS coated electrodes and binary PVA gel electrolytes with a conductive layer were designed and the electrochemical performance of the configurations was characterized. The effects of the conductive layer between binary electrolytes and the concentration of the KOH solution in the electrolytes were studied. It was observed that the conductive layer used between the gel electrolytes causes additional charging at the electrolyte/conductive layer interface and behaves like a serially connected capacitor to the double-layer capacitor. Interestingly, at a slow sweep rate (5 mV/s), the specific capacitance values of the assembled SCs decreased when a conductive layer was used but it increased when the sweep rate was fast (100 mV/s).     

Exploring the efficacy of AHA–BHA infused nanofiber skin masks as a topical treatment for acne vulgaris

This study investigates the efficacy of AHA–BHA infused nanofiber skin masks as a topical treatment for acne vulgaris. The skin is a vital organ that functions as a barrier to protect the body from external substances. In recent years, there has been a growing emphasis on skin treatment research. Hyaluronic acids (HAs) are commonly used in cosmetic and drug formulations to regulate excessive skin cornification, making them promising candidates for acne treatment. The introduction of HAs in dermatology has revolutionized the field of skin care, and they are used to treat various skin disorders, such as acne, ichthyosis, keratoses, warts, psoriasis, and photoaged skin. The antiaging benefits of HA have gained considerable attention in cosmetic dermatology, resulting in a surge in cosmetic products and skin care systems that contain HA. The study found that AHA–BHA-infused nanofiber skin masks are effective in treating acne vulgaris. The nanofiber masks were found to reduce inflammation, sebum production, and acne lesions. The study suggests that AHA–BHA-infused nanofiber skin masks could be a promising topical treatment for acne vulgaris.     

Nanoflower hydroxyapatite's effect on the properties of resin-based dental composite

To investigate the reinforcing effect of nanoflower-like hydroxyapatite (NFHA) in resin-based dental composites, we synthesized a novel NFHA using microwave irradiation (MW), hydrothermal treatment (HT), and sonochemical synthesis (SS). Silanized NFHA was then used as the reinforcing filler in dental resin composites. We characterized the structure and morphology of various HA nanostructures using x-ray diffraction, scanning electron microscope, and TEM. The mechanical performance of dental resin composites reinforced with silanized NFHA was measured using a universal testing machine. Spherical HA, synthesized through chemical precipitation (CP), served as the control group. One-way analysis of variance was employed for the statistical analysis of the acquired data. The results demonstrate that the nanoflower morphology significantly was improved mechanical and physical properties. After conducting trials, the NFHA synthesized using MW and HT showed a substantial enhancement in mechanical and physical properties compared to the other structures. Therefore, it can be concluded that NFHA can serve as a novel reinforcing HA filler, providing regenerative properties to resin composites with sufficient mechanical strength.     

Extensional rheology of raw natural rubber from new clones of Hevea brasiliensis

Natural rubber (NR) is a biopolymer whose properties depend on the molecular structure of the 1,4‐cis polyisoprene chains, nonrubber constituents, environmental conditions, etc. NR has been characterized by Mooney viscosity, Wallace plasticity, nitrogen content (%N). However, these cannot effectively account for clone's differences. The aim of this work is to use extensional rheology to characterize and differentiate NR samples as for clone type and the season of the year in comparison to the traditional characterizations. Three IAC 300 series and RRIM 600 clones of Hevea brasiliensis tapped between October 2006 (Oct_06) and August 2008 (Aug_08) were investigated. IAC 329 clones showed the least susceptibility to seasonal changes, whereas RRIM 600 was the most influenced. An opposite trend between extensional viscosity (η_E) and %N was established. The former was very sensitive to changes in the molecular structure of NR, being fundamental for monitoring purposes and strategic development of new rubber tree clones. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Influence of Alumina-Supported M–Pt Catalysts in DeNOx Reactions with M = Pd or Ir or Ru

To better understand N₂ formation in the selective catalytic reduction of NO _x by propene under oxidative atmosphere, we studied the catalytic behavior of bimetallics. Surface segregation phenomena may provoke geometric and electronic modifications of the catalytic active sites. To explain our results we invoked: (i) the facile way to oxidize the bimetallic aggregates, (ii) the presence of atoms with low coordination number able to be oxidized first and (iii) an eventual formation of like vic-diNO _x species on such bimetallics leading to N₂ formation.     

Effect of the degree of branching on the glass transition temperature of polyesters

Glass transition temperature dependence on the branching degree can be empirically estimated by excluding additional effects on this parameter as molecular weight distribution, end group interactions or crystallization. In this communication aliphatic–aromatic polyesters with a well defined degree of branching between 0% (linear) and 50% (hyperbranched) are investigated by differential scanning calorimetry. The hydrogen bonding effect of the OH-terminal groups was successfully extracted from the pure branching effect by protection of the end-functionalities. Fractionation of samples with variation of the branching degree and end-functionalities led to series of narrowly distributed molar masses. The dependence of the molecular weight on the glass transition temperature for different branching degrees was calculated and compared for polar and non-polar end groups.     

Surface analysis and adsorption behavior of caffeine as an environmentally friendly corrosion inhibitor at the copper/aqueous chloride solution interface

Abstract

Corrosion inhibitors based on environmentally friendly and harmless products are currently being studied and developed. The corrosion inhibition properties of caffeine (1,3,7-trimethylxanthine) on copper corrosion in aqueous chloride solution (3.5?wt.% NaCl) are analysed here using stationary and transient electrochemical methods, and a theoretical study based on density functional theory is carried out. Caffeine is a very competitive compared to the chemical inhibitors that are often used for copper protection. Electrochemical and impedance experiments reveal that the protective efficiency of caffeine reaches a value of 96% at a concentration of 10^?2?mol L^?1. Based on these results, the Langmuir model appears to be the best representation of the adsorption of caffeine onto the copper surface. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) were used to determine the surface morphology and the chemical composition of the copper surface in chloride media, in the absence and presence of caffeine. The results show the development of a mechanism of corrosion inhibition. In order to confirm the correlation between the inhibitory effect and the molecular structure of caffeine, quantum chemical parameters are used to calculate its electronic properties.     

Preparation of hybrid PU/PCL fibers from steviol glycosides via electrospinning as a potential wound dressing materials

In this study, the synthesis and application of biocompatible steviol glycosides based polyurethane/poly (ε-caprolactone) (PU/PCL) fibers was performed by electrospinning as a potential wound dressing materials that can be used for the closure of nonhealing wounds. During electrospinning, steviol glycoside-based polyurethane structures were used in blend formation with poly (ε-caprolactone) for easy producibility. Steviol glycosides are a natural abundant and easily accessible source as the main component of the wound dressing material due to their free hydroxyl groups, high biocompatibility, and hydrophilicity. The structure of steviol glycosides is composed of saccharide units and the free OH groups. Thus, steviol glycosides act as a crosslinker within the polyurethane structure and provides mechanical strength. For the production of steviol glycosides based PU/PCL fibers first, the steviol glycosides as a monomer were isolated from the stevia rebudiana. Then, polyurethane structures containing stevia glycoside were synthesized with hexamethylene diisocyanate, lactose and PEG-200 by solution polymerization technique. PCL was added to the prepared polyurethanes in a ratio of 1:2 and formation of nanofiber structure. The prepared wound dressing material was characterized by Fourier transform infrared, atomic force microscopy, and scanning electron microscope techniques. Swelling degree, water content and oxygen permeability assay of the steviol glycosides based PU/PCL wound dressing material was determined. In biocompatibility test, cell viability value of PU/PCL fibrous materials in indirect cytotoxicity test was determined as 86.9% and cell adhesion on hybrid PU/PCL fibers was showed as morphological. In accordance with this target, the steviol glycosides based PU/PCL wound dressing material can be produced easily and low cost. As a result, the wound dressing materials obtained with their high biocompatibility and low costs will be an effective and fast method for the healing of open wounds of diabetics.