烯丙基酚氧树脂改性双马来酰亚胺体系的优化

通过环氧树脂与二烯丙基双酚A合成了一种烯丙基酚氧树脂,用以增韧双马来酰亚胺。在单因素试验的基础上,根据Box-Benhnken的中心组合试验设计原理,选取改性树脂体系组分为影响因子,应用响应面法进行3因素3水平的18组的设计试验,改性树脂性能(弯曲强度,冲击强度,热变形温度)为响应值,对改性树脂组分配比进行优化。结果表明,改性树脂组分配比BMI、DDS、APO、DABPA、DAP为2∶1∶0.2∶0.84∶0.1(物质的量比)时,综合2性能最好,此时改性双马树脂体系的冲击强度可达到21.4 k J/m,弯曲强度为200.5 MPa,热变形温度为195.8℃。     

Utilization of the yarn pullout test in estimation of the reserved energy of rib knitted fabrics

The yarn pullout test is a prevailing and particular method to evaluate the effects of yarn properties and the structural characteristics of the fabric on the fabric mechanical performance. In this research, a theoretical model of yarn pull out is presented to determine the reserved energy of weft-knitted fabrics with rib 1 × 1 structure. This model is based on the fabric dimensional properties, i.e. stitch length, wale density, yarn diameter and contact angle of yarns. In order to appraise the proposed model, five different double jersey weft-knitted fabrics with rib 1 × 1 structure were produced and exposed to pullout test. Comparison between deviations of theoretical results from experimental results demonstrates that the presented theoretical model exhibits a rational estimation of the reserved energy in these fabrics.     

Synthesis of polymeric electrospun nanofibers for application in waterproof‐breathable fabrics

This study focuses waterproof‐breathable fabric development by applying electrospun web of polyurethane (PU), PAN, and PES directly onto the substrate fabric. Advantages of textile fabrics of elastomeric nanofibrous membranes over gortex specimen are the mass production feasibility, high elastomeric properties, more body comfort parameters, and fabric production without holes and needle traces formation. In this work, we identified the PU nanofibrous membrane as the best and useful web for application in waterproof‐breathable fabrics. Air permeability, water vapor transport rate, and resistance to water penetration average value for the prepared PU fibers web (sample of S1) were about 10 ml/s, 430 g/m²/24 h, 15 cm H₂O. To improve waterproof‐breathable characteristics of the membrane, the effects of electrospinning parameters on the fibers morphology and waterproof‐breathable characteristics were investigated. PU concentration of 12% (w/w) and electrospinning voltage of 12 kV were identified as optimal conditions to reach uniform and fine PU nanofibers formation without any beads. Air permeability, water vapor transport rate, and resistance to water penetration average value for the final sample were recorded as about 2.5 ml/s, 840 g/m²/24 h, and 44 cm H₂O, correspondingly. POLYM. ENG. SCI. 56:143–149, 2016. © 2015 Society of Plastics Engineers     

Mass‐transfer enhancement in single drop extraction in the presence of magnetic nanoparticles and magnetic field

Magnetite nanoparticles with an average particle size of 28.8 nm were synthesized, coated with oleic acid, and characterized using various techniques such as DLS, FT‐IR, SEM, XRD, VSM, and UV‐Vis analysis. A nanofluid consisting of synthesized nanoparticles and 5 wt % acetic acid in toluene as the dispersed phase was prepared and used in the chemical test system, Toluene‐Acetic Acid‐Water, for the single drop extraction in the presence and absence of an external oscillating magnetic field. Influences of various operating and design parameters such as nanoparticle concentration, drop diameter, and the applied current and frequency on the overall mass‐transfer coefficients for the mass‐transfer direction from d→c were investigated carefully. The obtained results were used to propose a general correlation for the mass‐transfer enhancement. It was found that the maximum mass‐transfer enhancement compared with that obtained in the absence of nanoparticles and the oscillating magnetic field is about 259%. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4466–4479, 2016     

Chemical vapor deposition of poly(3‐alkylthiophene) nanoparticles on fabric: Chemical and electrochemical characterization

Chemical vapor deposition of poly(3‐methylthiophene) and poly (3‐hexylthiophene) as conductive polymers on the surface of polyester fabrics was successfully obtained. Fourier transform infrared spectroscopy confirmed the formation of polymers on surface of fabrics (the fingerprint of polythiophenes, υ 600–1500 cm^?1). The uniformity of deposition and nanoparticles (average size of 60 nm) were proved with scanning electron microscopy. Electrochemical impedance spectroscopy showed that P3HT‐coated samples offer higher conductivity in compared to P3MT‐coated samples. The impedance modulus of P3HT‐coated samples was lowered nine times to that of row materials and reached to c8000 Ω. The samples have also shown electrochromic properties under electrical current, changing its color from yellowish green at 0 V to dark green at +12 V for poly (3‐hexylthiophene) samples and from brown at 0 V to red at +12 V for poly(3‐methylthiophene)‐coated fabrics (V = 0 V, λ = 450 nm; V = 12 V, λ = 650 nm). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40673.     

Development of High Strength and Toughness Non-Heated Al–Mg–Si Alloys for High-Pressure Die-Casting

Based on the 3 factors and 3 levels orthogonal experiment method, compositional effects of Mg, Si, and Ti addition on the microstructures, tensile properties, and fracture behaviors of the high-pressure die-casting Al-x Mg-y Si-z Ti alloys have been investigated. The analysis of variance shows that both Mg and Si apparently infl uence the tensile properties of the alloys, while Ti does not. The tensile mechanical properties are comprehensively infl uenced by the amount of eutectic phase(α-Al + Mg_2Si), the average grain size, and the content of Mg dissolved into α-Al matrix. The optimized alloy is Al-7.49 Mg-3.08 Si-0.01 Ti(wt%), which exhibits tensile yield strength of 219 MPa, ultimate tensile strength of 401 MPa, and elongation of 10.5%. Furthermore, contour maps, showing the relationship among compositions, microstructure characteristics, and the tensile properties are constructed, which provide guidelines for developing high strength and toughness Al–Mg–Si–Ti alloys for high-pressure die-casting.     

Mechanochemical sulfidization of a mixed oxide-sulphide copper ore by co-grinding with sulfur and its effect on the flotation efficiency

Mechanochemical sulfidization of a mixed sulfide/oxide copper ore by co-grinding with sulfur and additives including Mg(NO₃)₂ and Fe(NO₃)₃ salts and iron, aluminum and magnesium powders was investigated for the first time. Also, the influence of sulfidization during the wet-milling process was examined on the separation efficiency and recovery of copper in detail. The results demonstrated that co-grinding with sulfur solely had the best flotation performance at the value of 0.5 wt.% and it was attributed to the possible existence of S-O bonding on copper oxides surfaces. In addition, adding magnesium nitrate salt, magnesium powder, iron nitrate salt and aluminum powder as additive associated with 0.5 wt% sulfur into ball milling caused the flotation improvement at the amounts of 0.2 wt%, 0.2 wt%, 0.5 wt% and 0.5 wt%, respectively. Also, the effect of grinding time and sulfidization pH with 0.5 wt% sulfur solely was determined and pHs of 7.5 to 8.5 gave the best results. The highest recovery (75.76%) and separation efficiency (63.44%) were achieved at pH of 7.5 and 8.5, respectively.     

Genomics and Epigenomics of Gestational Diabetes Mellitus: Understanding the Molecular Pathways of the Disease Pathogenesis

One of the most common complications during pregnancy is gestational diabetes mellitus (GDM), hyperglycemia that occurs for the first time during pregnancy. The condition is multifactorial, caused by an interaction between genetic, epigenetic, and environmental factors. However, the underlying mechanisms responsible for its pathogenesis remain elusive. Moreover, in contrast to several common metabolic disorders, molecular research in GDM is lagging. It is important to recognize that GDM is still commonly diagnosed during the second trimester of pregnancy using the oral glucose tolerance test (OGGT), at a time when both a fetal and maternal pathophysiology is already present, demonstrating the increased blood glucose levels associated with exacerbated insulin resistance. Therefore, early detection of metabolic changes and associated epigenetic and genetic factors that can lead to an improved prediction of adverse pregnancy outcomes and future cardio-metabolic pathologies in GDM women and their children is imperative. Several genomic and epigenetic approaches have been used to identify the genes, genetic variants, metabolic pathways, and epigenetic modifications involved in GDM to determine its etiology. In this article, we explore these factors as well as how their functional effects may contribute to immediate and future pathologies in women with GDM and their offspring from birth to adulthood. We also discuss how these approaches contribute to the changes in different molecular pathways that contribute to the GDM pathogenesis, with a special focus on the development of insulin resistance.     

Evaluation of Antioxidant and Antimicrobial Activities of Essential Oils from Carum copticum Seed and Ferula assafoetida Latex

Carum copticum and Ferula assafoetida have several medicinal properties including antispasmodic, carminative, sedative, analgesic, and antiseptic. Reactive oxygen species (ROS), reactive nitrogen species (RNS), hydrogen peroxide (H₂O₂), and thiobarbituric acid reactive substances (TBARS) scavenging activities of Carum and Ferula oils along with their antibacterial and antifungal activities were examined. Thymol (40.25%), γ‐terpinene (38.7%) and p‐cymene (15.8%) were detected as the main components of Carum oil while, β‐pinene (47.1%), α‐pinene (21.36%), and 1, 2‐dithiolane (18.6%) were the main components of Ferula oil. Inhibitory concentrations (IC50) for total radical scavenging were between 40 and 60 and 130 and 160 μg/mL of Carum and Ferula oil, respectively. Minimal inhibitory concentration (MIC) for Salmonella typhi, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Aspergillus niger, and Candida albicans were 78 ± 8, 65 ± 7, 14 ± 3, 5 ± 2, 5.6 ± 1.3, and 8.8 ± 2.2 μg/mL of Carum oil, respectively. MIC for S. typhi, E. coli, S. aureus, B. subtilis, A. niger, and C. albicans were >200, >200, 125 ± 17, 80 ± 12, 85 ± 5, and 90 ± 11 μg/mL of Ferula oil, respectively. Accordingly, Carum and Ferula oils could be used as safe and effective natural antioxidants to improve the oxidative stability of fatty foods during storage and to preserve foods against food burn pathogens. Practical Application : This study clearly demonstrates the potential of Carum and Ferula oil especially Carum oil as natural antioxidant and antimicrobial agent. The chemical composition of essential oils was identified. Thus, identification of such compounds also helps to discover of new antioxidant, antibacterial and antifungal agents for potential applications in food safety and food preservation.     

CFD modeling of flow and heat transfer in a thermosyphon

In the present study a gas/liquid two-phase flow and the simultaneous evaporation and condensation phenomena in a thermosyphon was modeled. The volume of fluid (VOF) technique was used to model the interaction between these phases. Experiments in a thermosyphon were carried out at different operating conditions. The CFD predicted temperature profile in the thermosyphon was compared with experimental measurements and a good agreement was observed. It was concluded that CFD is a useful tool to model and explain the complex flow and heat transfer in a thermosyphon.