Determination of the Thermal Degradation Kinetic Parameters of Carbon Fibre Reinforced Epoxy Using TG

In this work, a kinetic study on the thermal degradation of carbon fibre reinforced epoxy is presented. The degradation is investigated by means of dynamic thermogravimetric analysis (TG) in air and inert atmosphere at heating rates from 0.5 to 20°C min⁻¹ . Curves obtained by TG in air are quite different from those obtained in nitrogen. A three-step loss is observed during dynamic TG in air while mass loss proceeded as a two step process in nitrogen at fast heating rate. To elucidate this difference, a kinetic analysis is carried on. A kinetic model described by the Kissinger method or by the Ozawa method gives the kinetic parameters of the composite decomposition. Apparent activation energy calculated by Kissinger method in oxidative atmosphere for each step is between 40–50 kJ mol⁻¹ upper than E _a calculated in inert atmosphere. The thermo-oxidative degradation illustrated by Ozawa method shows a stable apparent activation energy (E _a ≈130 kJ mol⁻¹ ) even though the thermal degradation in nitrogen flow presents a maximum E _a for 15% mass loss (E _a ≈60 kJ mol⁻¹ ). This revised version was published online in July 2006 with corrections to the Cover Date.     

Electrochemical Study of the Interactions of DNA with Redox‐Active Molecules Based on the Immobilization of dsDNA on the Sol‐Gel Derived Nano Porous Hydroxyapatite‐Polyvinyl Alcohol Hybrid Material Coating

A novel type of sol‐gel inorganic‐organic hybrid material coated on glassy carbon electrode used for immobilization of double‐stranded DNA (dsDNA) and study of dsDNA with redox‐active molecules was developed. The hybrid material coating was produced by sol‐gel method with nano hydroxyapatite (HAp)‐polyvinyl alcohol (PVA). The optimum composition of the hybrid material was first examined, and the morphology of the nano HAp‐PVA coatings was investigated with the help of Scanning Electron Microscope (SEM). DsDNA was immobilized in/on the nano HAp‐PVA hybrid coatings by adsorption and the characteristics of the dsDNA/HAp‐PVA/GCE were studied by cyclic voltammetry (CV) using the probes of Co(phen) and Fe(CN) . The results indicate that the dsDNA can be immobilized on the nano porous HAp‐PVA coating effectively and its stability can satisfy the necessity of study on the interactions of dsDNA with redox‐active molecules on the electrode surface. Co(bpy) and Co(phen) were used as the model molecule to study the interactions of dsDNA with redox‐active molecules. Information such as ratio (K_Ox/K_Red) of the binding constant for the oxidized and reduced forms of a bound species, interaction mode, including change in the mode of interaction, and “limiting” ratio K /K at zero ionic strength (μ) can be obtained using dsDNA/HAp‐PVA/GCE with about 2 μg of DNA samples.     

Is Bitcoin’s Carbon Footprint Persistent? Multifractal Evidence and Policy Implications

The Bitcoin mining process is energy intensive, which can hamper the much-desired ecological balance. Given that the persistence of high levels of energy consumption of Bitcoin could have permanent policy implications, we examine the presence of long memory in the daily data of the Bitcoin Energy Consumption Index (BECI) (BECI upper bound, BECI lower bound, and BECI average) covering the period 25 February 2017 to 25 January 2022. Employing fractionally integrated GARCH (FIGARCH) and multifractal detrended fluctuation analysis (MFDFA) models to estimate the order of fractional integrating parameter and compute the Hurst exponent, which measures long memory, this study shows that distant series observations are strongly autocorrelated and long memory exists in most cases, although mean-reversion is observed at the first difference of the data series. Such evidence for the profound presence of long memory suggests the suitability of applying permanent policies regarding the use of alternate energy for mining; otherwise, transitory policy would quickly become obsolete. We also suggest the replacement of ‘proof-of-work’ with ‘proof-of-space’ or ‘proof-of-stake’, although with a trade-off (possible security breach) to reduce the carbon footprint, the implementation of direct tax on mining volume, or the mandatory use of carbon credits to restrict the environmental damage.     

林火中的阴燃现象:研究前沿与展望

森林中的植物腐殖质和有机泥炭土的阴燃是地球上尺度最大的燃烧与火灾现象,造成了巨大的经济损失及跨国界的雾霾,并严重破坏了生态系统.本文综述了阴燃林火的基础燃烧理论和化学反应机理,总结了其点火、火蔓延和熄火的行为特性.同时,归纳了近年来泥炭阴燃火的研究动态,包括如何通过小尺度的阴燃实验理解大尺度的阴燃林火,如何构建阴燃的数...     

GO-SWCNT Buckypapers as an Enhanced Technology for Water Decontamination from Lead

Water decontamination is an important challenge resulting from the incorrect disposal of heavy metal waste into the environment. Among the different available techniques (e.g., filtration, coagulation, precipitation, and ion-exchange), adsorption is considered the cheapest and most effective procedure for the removal of water pollutants. In the last years, several materials have been tested for the removal of heavy metals from water, including metal-organic frameworks (MOFs), single-walled carbon nanotubes (SWCNTs), and graphene oxide (GO). Nevertheless, their powder consistency, which makes the recovery and reuse after adsorption difficult, is the main drawback for these materials. More recently, SWCNT buckypapers (SWCNT BPs) have been proposed as self-standing porous membranes for filtration and adsorption processes. In this paper, the adsorption capacity and selectivity of Pb²⁺ (both from neat solutions and in the presence of other interferents) by SWCNT BPs were evaluated as a function of the increasing amount of GO used in their preparation (GO-SWCNT buckypapers). The highest adsorption capacity, 479 ± 25 mg g⁻¹, achieved for GO-SWCNT buckypapers with 75 wt.% of graphene oxide confirmed the effective application of such materials for cheap and fast water decontamination from lead.     

Periodic Mesoporous Organosilica Nanoparticles for CO2 Adsorption at Standard Temperature and Pressure

(1) Background: Due to human activities, greenhouse gas (GHG) concentrations in the atmosphere are constantly rising, causing the greenhouse effect. Among GHGs, carbon dioxide (CO₂) is responsible for about two-thirds of the total energy imbalance which is the origin of the increase in the Earth’s temperature. (2) Methods: In this field, we describe the development of periodic mesoporous organosilica nanoparticles (PMO NPs) used to capture and store CO₂ present in the atmosphere. Several types of PMO NP (bis(triethoxysilyl)ethane (BTEE) as matrix, co-condensed with trialkoxysilylated aminopyridine (py) and trialkoxysilylated bipyridine (Etbipy and iPrbipy)) were synthesized by means of the sol-gel procedure, then characterized with different techniques (DLS, TEM, FTIR, BET). A systematic evaluation of CO₂ adsorption was carried out at 298 K and 273 K, at low pressure. (3) Results: The best values of CO₂ adsorption were obtained with 6% bipyridine: 1.045 mmol·g⁻¹ at 298 K and 2.26 mmol·g⁻¹ at 273 K. (4) Conclusions: The synthetized BTEE/aminopyridine or bipyridine PMO NPs showed significant results and could be promising for carbon capture and storage (CCS) application.     

台风对沿海地区气溶胶光学特性的影响分析

利用CE317太阳辐射计对2005年第19号台风登陆前后期问(9月29 H至10月6日)进行观测实验,采用Langley法分析台风对中国大陆沿海地区气溶胶光学特性的影响.指出台风过后气溶胶光学特性明显发生改变,气溶胶大粒子数增多,小粒子数减小.气溶胶光学厚度、Angstr(o)m波长指数α和大气混浊度系数β为测量期间最低分别为0.132(550 nm处),0.861和0.079.同时利用实验期间APS3321空气动力学粒度仪分析的气溶胶单位体积数粗细质粒所占比重、气溶胶粒子尺度谱分布和实测的日际气溶胶粒子数浓度对实验分析结果.α,β进行对比,发现它们之间的一致性很好.     

热丝和射频等离子体化学气相沉积法制备定向碳纳米管薄膜

采用热丝和射频等离子体复合化学气相沉积设备(PE-HF-CVD),以CH4、H2和N2为反应气体.在较低衬底温度下(500℃),用简单的催化剂制备方法--旋涂法在硅片上涂覆Ni(NO3)2溶液,经热处理及H2还原后的Ni颗粒为催化剂,在硅衬底上制备出了垂直于硅片且定向生长的碳纳米管薄膜.扫描电子显微镜(SEM)和透射电子显微镜(TEM)结果显示,1 mol/l的硝酸镍溶液旋涂硅片所得催化剂制得的碳纳米管管径为30～50 nm,长度超过4μm,定向性好.并用拉曼光谱(Raman)对不同摩尔浓度Ni(NO3)2溶液条件下制备的碳纳米管薄膜样品进行了表征.     

乌骨鸡活性肽对体外非酶糖基化的抑制作用

采用正交实验优化了体外非酶糖基化反应体系,体系中加入不同浓度的乌骨鸡活性肽I、Ⅱ37 ℃孵育,同时以肌肽为阳性对照,观察乌骨鸡活性肽对非酶糖基化反应的影响.通过测定预定时间体外非酶糖基化体系的吸光度和荧光值计算乌骨鸡活性肽对非酶糖基化反应的抑制率和对非酶糖基化终产物生成的抑制率.结果表明乌骨鸡活性肽Ⅱ对体外非酶糖基化反应和非酶糖基化终产物的生成均具有较强的抑制作用.     

Effect of Wearing Surgical Face Masks on Gas Detection from Respiration Using Photoacoustic Spectroscopy

Wearing surgical face masks is among the measures taken to mitigate coronavirus disease (COVID-19) transmission and deaths. Lately, concern was expressed about the possibility that gases from respiration could build up in the mask over time, causing medical issues related to the respiratory system. In this research study, the carbon dioxide concentration and ethylene in the breathing zone were measured before and immediately after wearing surgical face masks using the photoacoustic spectroscopy method. From the determinations of this study, the C₂H₄ was established to be increased by 1.5% after one hour of wearing the surgical face mask, while CO₂ was established to be at a higher concentration of 1.2% after one hour of wearing the surgical face mask, when the values were correlated with the baseline (control).