Selected physical and chemical properties of mechanically extracted neem seed oil sourced as a preservative for ligno-cellulose in south-western Nigeria

Most of the seeds produced by neem （Azadirachta indica A. Juss） trees in Nigeria are currently underutilized. Hence, relevant literature provides only limited information conceming many of the seed oils from this country, especially where it concems the potential applications of these oils as preservatives for ligno-cellulose against bio-deterioration. Using standard procedures therefore, this study was carried out to evaluate and document selected physical and chemical properties of neem seed oil （NSO）, mechanically extracted using a cold press at 31.03 N-mm^-2 pressure and a room temperature of 25 ± 2℃. The results show that oil yield was 38.42% with a specific gravity of 0.91 ± 0.01. The amount of acid was 18.24 ± 1.31 mg KOH.g^-1 and that of iodine 93.12 ± 2.01 g-100 g^- 1, while saponification and peroxide values were 172.88 ± 2.06 and 1.42 ± 0.04 mg·g^-1 respectively. The implication of the values obtained, particularly those for the chemical properties, as they concern the potential application of NSO as a preservative for ligno-eellulose, is likely that it may be useful in this regard since the values may support some of the documented anti-microbial properties of the oil, although other physical and chemical properties that may affect this potential are recommended for investigations. Conclusions and other recommendations follow in line with the results of the study.

Effect of Combined Chemical Treatment on Physical, Mechanical and Chemical Properties of Posidonia Fiber

The aim of this study is to investigate the effect of chemical treatment method on the properties of Posidonia fibers. The chemical treatment which is carried out is a combined hydrogen peroxide and sodium hydroxide treatment. First, an investigation of the treatment processes was undertaken. Secondly, the physical properties (linear density, diameter and ratio length per diameter), the mechanical properties (tenacity, elongation) and chemical properties (FT-IR spectra and X ray diffraction) of posidonia fibers were investigated. The optimum operating conditions were identified using a factorial design.

The Thermal Decomposition Mechanism and the Quantum Chemical Calculation of[Mg（H2O）6]（NTO）2·2H2O

[Mg(H2O)6](NTO)2·2H2O Was prepared by adding magnesium carbonate hydroxide to the aqueous solution of 3-nitro-1，2，4-triazol-5-one(NTO)．Its thermal decomposition mechanism was studied by DSC，TG／DTGand IR．The quantum chemical calculation on the title complex as a structure unit with the experimental geometry as atartmg values was carried out at B3LYP level with 6-31G basis set．The results show that the bonds between the coordinate waters and the Mgatom have certain extent covalent character．The net charges on nitrogen atoms of the NTO ring appear to be negative while the nitrogen atom on the nitro group(—NO2)appears to be positive which indicates—NO2 will lost first when the complex is heated to some uniform temperature and this result is in agreement with that of the thermal decomposition experiment．

Effect of Chemical Extraction on Physicochemical and Mechanical Properties of Doum Palm Fibres

The aim of this study is to investigate the effect of chemical extraction method on the properties of doum palm fibres. The method of extraction which is carried out is a soda treatment. First, an investigation of the extraction processes was undertaken. Secondly, the physical properties (surface morphology, density, linear density and diameter), the mechanical properties (tenacity, strain) and chemical properties (FT-IR spectra) of doum palm fibres were inspected. Finally, a comparison between properties of doum palm fibres and other vegetal ones has been included. Results indicates an influence of soda treatment on properties of Doum palm fibers. In fact, there is an improvement on fibers diameter and linear density while increasing soda concentration, temperature and treatment duration. Moreover, the studied fibers have a low density which does not exceed 1. The fibers tenacity achieved the maximum value of 20.86 cN/Tex when precessing in the following combination (0.75 N, 100°C and 180 mn). In the end, the FTIR spectra reveals a change in structure after this alkali treatment while increasing the cellulose amount exposed on the fiber surface and consequently the number of possible reaction sites (OH groups).

Dissipative particle dynamics simulation of wettability alternation phenomena in the chemical flooding process

Wettability alternation phenomena is considered one of the most important enhanced oil recovery （EOR） mechanisms in the chemical flooding process and induced by the adsorption of surfactant on the rock surface. These phenomena are studied by a mesoscopic method named as dissipative particle dynamics （DPD）. Both the alteration phenomena of water-wet to oil-wet and that of oil-wet to water-wet are simulated based on reasonable definition of interaction parameters between beads. The wetting hysteresis phenomenon and the process of oil-drops detachment from rock surfaces with different wettability are simulated by adding long-range external forces on the fluid particles. The simulation results show that, the oil drop is liable to spread on the oil-wetting surface and move in the form of liquid film flow, whereas it is likely to move as a whole on the waterwetting surface. There are the same phenomena occuring in wettability-alternated cases. The results also show that DPD method provides a feasible approach to the problems of seepage flow with physicochemical phenomena and can be used to study the mechanism of EOR of chemical flooding.

边界润滑条件下天然橡胶-钢磨损机理的研究

研究了边界润滑条件下天然橡胶磨损 2 0 #钢的机理 .采用扫描电子显微镜和 X射线光电子能谱仪分析了钢和橡胶的磨损表面形貌、元素含量和化学状态 ,用镜面全反射傅立叶红外光谱仪分析了橡胶磨损表面官能团的变化 .结果表明 :2 0 #钢被天然橡胶磨损的物理过程为磨粒磨损 (微切削 ) ;2 0 #钢被天然橡胶磨损的化学机制包括钢本身的氧化 (主要氧化产物为 Fe2 O3 、Fe O和 Fe3 O4) ,钢氧化物与天然橡胶大分子链间的反应 ,钢氧化物与氧化的矿物油烷烃链间的反应以及与矿物油中 S元素间的反应 ,其主要反应产物为含有 Fe- C的钢 -聚合物以及含有 Fe-

A Fractal Model for Effective Thermal Conductivity of Isotropic Porous Silica Low-k Materials

We establish a new model based on fractal theory and cubic spline interpolation to study the effective thermal conductivity of isotropic porous silica low-k materials. A 3D fractal model is introduced to describe the structure of the silica xerogel and silica hybrid materials （such as methylsilsesquioxane, MSQ）. Combined with fractal structure, a more suitable medium approximation is developed to study the isotropic porous silica xerogel and MSQ materials. Cubic spline interpolation for fitting discrete predictions from the fractal model is used to obtain the continuous function of the effective thermal conductivity versus porosity. Compared with other common models, the effective thermal conductivity predicted by our model presents better agreement with the experimental data for all porosity. These results indicate that the proposed model is valid.

Determination of microcapsule physicochemical, structural, and mechanical properties

Research into the fundamental properties of microcapsules and use of the results to develop a wide variety of products in industries such as printing, fast-moving consumer goods, construction, pharmaceuticals, and agrochemicals is a dynamic and ever-progressing field of study. For microcapsules to be effective in providing protection from harsh environments or delivering large payloads, it is essential to have a good understanding of their properties to enable quality control during formulation, storage, and applications. This review aims to outline the commonly used techniques for determining the physicochemical, struc- tural, and mechanical properties of microcapsules, and highlights the interlinked nature of these three areas with respect to the end-use industrial application. This review provides information on techniques that are well supported in the literature, and also examines microcapsule analytical techniques that will become more prevalent as a result of new technological developments or extensions from other areas of study.

Clockwise vs Counter-Clockwise I-V Hysteresis of Point-Contact Metal-Tip/Pr0.7 Ca0.3MnO3/Pt Devices

Metal-tip/Pr0.7Ca0.3MnO3/Pt devices possess two types of I-V hysteresis： clockwise vs counter clockwise depending on the tip materials. The criteria for categorization of these two types of devices can be simply based on whether the Gibbs free energy of oxidation for the metal tip is lower or higher than that of PCMO, respectively. While the clockwise hysteresis can be attributed to electric field induced oxidation/reduction, the counter clockwise hysteresis can be explained by oxygen vacancy migration in an electrical field. Alternating-current conductance spectra also reveal distinct hopping barriers between these two categories of devices at high resistive states.

Self-Assembled Colloidal Crystals in Capillary with Its Fiber Junction

Silica microspheres self-assembled in glass capillary are investigated. Monodisperse silica microsphere dispersions in diameter 320nm are self-organized into a bulk cylindrical colloidal crystal by evaporation induced nucleation and crystallization. The resulting colloidal crystals are characterized by optical microscopy and scanning electronic microscopy （SEM）, and the SEM images show these crystals dominate in fcc lattice with its （111） crystallographic axis as longitudinal. The colloidal crystal filled capillary is packaged into a heat-shrink plastic tube and a fiber measurement system is designed to measure the optical property of colloidal bulk in capillary. It is found that an appreciable bandgap appears at wavelength 686 nm from the transmission spectroscopy, which is consistent with the theoretical estimation. A considerable photonic band gap of up to -10 dB and a steep photonic band edge of up to 0.25 dB/nm indicate that silica microspheres are promising for implementing optical filter applications in fiber systems.

Observational study of the physical and chemical characteristics of the winter radiation fog in the tropical rainforest in Xishuangbanna, China

We conducted a three-month field experiment focusing on the physical and chemical characteristics of fog in a tropical rainforest in Xishuangbanna,Southwest China,in the winter of 2019.In general,the fog would form at midnight and persist because of the increased long-wave radiative cooling combined with the high relative humidity,gentle breeze,and a relatively low aerosol number concentration in the forest;the fog would dissipate before noon due to the increasing turbulence near the surface.This diurnal cycle is typical for radiation fog.The microphysical fog properties included a relatively low number concentration of the fog droplet,large droplet size,high liquid water content,narrow droplet number-size distribution,and high supersaturation.The chemical properties showed that the fog water was slightly alkaline with low electrical conductivity,whereas the highest proportions of anions and cations therein were Cl^(−)and Ca^(2+),respectively;the chemical components were enriched in small fog droplets.In addition,we indirectly calculated the fog supersaturation according to theκ-Köhler theory.We found that condensation broadens the droplet number-size distribution at relatively low supersaturation,which is positively correlated with the fog-droplet number concentration and negatively correlated with the droplet mean-volume diameter;this affects the key microphysical processes of fog.

高韧性尼龙6-聚氧化乙烯醚复合材料制备及复合形式对合成及结构性能影响

分别通过物理分散和化学嵌段形式将柔性端氨基聚氧化乙烯醚(PEA)引入尼龙6(PA6)体系制备了PA6/PEA共混物和PA6-b-PEA共聚物。研究发现,PEA的引入使得聚合反应活性降低,活化能增大,共聚体系中PEA-TDI大分子引发剂的长链效应和位阻效应对聚合反应的延缓作用更明显。当复合材料中PEA含量相同时,共混体系的结晶性能优于共聚体系,而当嵌段的PEA含量较高时,共聚体系形成少量γ晶。随PEA含量增加,PA6-PEA复合材料的弹性平台和应变硬化现象愈加明显。嵌段的柔性PEA链段使共聚分子链排列不再规整,分子链运动能力大幅提升,从而使PA6-b-PEA共聚物具有高抗冲击性,其冲击断面产生大形变和"毛发"结构,呈现韧性断裂特征。

基于固废电石渣-高炉矿渣的胶凝材料理化与力学性质研究

电石渣(CS)和高炉矿渣(GGBS)是典型的工业固废,在一定条件下能够生成良好的胶凝材料,代替水泥对软弱土体进行固化稳定。文章以CS为基本材料,GGBS为添加剂,采用密度(ρ)测试、孔隙液电导率(γ)测试、pH值测试、无侧限抗压强度(q^(u))测试等,对自然养护条件下GGBS掺量和养护龄期对胶凝材料的理化与力学性质的影响进行研究。结果表明:GGBS掺量能够有效促进ρ的上升,使γ和pH值降低;养护龄期的延长则会引起ρ、γ和pH值的降低。qu随着GGBS掺量提升和养护龄期的增长而提升,在3 d~7 d中提升幅度较大。胶凝材料的应力-应变曲线可分为弹性、塑性、强度屈服3个阶段,破坏应变稳定在3.5%~5.4%之间。由理化反应和力学性质的变化,可将胶凝材料在28 d中的反应过程分为高活性、稳定和碳化3个阶段。

NdFeB磁体表面环保型Zn-Al涂层的盐雾腐蚀行为

目的 研究NdFeB磁体表面环保型Zn-Al涂层在盐雾环境中的腐蚀行为。方法 采用SEM、XRD、EDS、拉曼光谱、傅里叶变换红外光谱等对Zn-Al涂层的形貌、物相、成分结构进行分析。通过电化学曲线探究Zn-Al涂层在盐雾环境中的腐蚀机理。结果 在NdFeB磁体表面制备的环保型Zn-Al涂层的耐盐雾腐蚀时间不少于1 000 h。在盐雾腐蚀环境中,Zn-Al涂层表面逐渐被白锈覆盖,失去金属光泽,腐蚀至1 126 h时,Zn-Al涂层表面出现红色锈点,涂层微观组织呈蜂窝状结构,并出现微裂纹。腐蚀产物由Zn_(5)(OH)_(8)Cl_(2)·H_(2)O、Al_(9)SiAl_(12)(OH)_(18)(AlO_(4))(Si_(5)O_(16))Cl、Fe_(2)O_(3)和极少量的Zn、Al组成。腐蚀前期,Zn-Al涂层表面的钝化膜、硅烷膜起保护作用;随腐蚀进行,膜层破坏暴露出片状金属粉,金属粉活化,涂层发挥牺牲阳极保护作用;腐蚀后期,腐蚀介质通过涂层微裂纹穿透涂层至磁体,涂层牺牲阳极的保护作用和物理屏蔽保护作用显著减弱,直至失效。结论 环保型Zn-Al涂层可显著提高NdFeB磁体的耐中性盐雾腐蚀性能。

Interaction between B-Doped C60 Fullerene and Glycine Amino Acid from First-Principles Simulation

The possibility of formation of complexes between glycine and boron doped C60 （C59B） fullerene is investigated and compared with that of C60 fullerene by using the density functional theory calculations. It has been found that the binding of glycine to C59B generated the most stable complexes via its carbonyl oxygen active site, with a binding energy of-37.89 kcal/mol, while the glycine molecule prefers to bind to the pure C60 cage via its amino nitrogen active site, consistent with the recent experimental and theoretical studies. We have also tested the stability of the most stable Gly-C59B complex with ab initio molecular dynamics simulation, carried out at room temperature. These indicate that the B-doped C60 fullerenes seem to be more suitable materials for bindings to proteins than pure C60 fullerenes.

Magnetic Properties of Ni-Zn Ferrite Prepared with the Layered Precursor Method

We prepare NiZnFe2O4 soft magnetic ferrites with different molar ratios with the layered precursor method and investigate their magnetic properties. In the layered precursor, metal ions are scattered on the layer plate in a certain way on account of the effect of lowest lattice energy and lattice orientation. After high temperature calcinations, spinel ferrites with uniform structural component and single magnetic domain can be obtained, and the magnetic property is improved greatly. NiZnFe2O4 ferrites prepared have the best specific saturation magnetization of 79.15 emu·g^-1, higher than that of 68 emu·g^-1 prepared by the chemical co-precipitation method and that of 59 emu·g^-1prepared by the emulsion-gel method. Meanwhile the coercivity of NiZnFe2O4 ferrites prepared by layered precursor method is 14 kA·m^-1, lower than that of 50 emu·g^-1 prepared by the co-precipitation method and that of 59 emu·g^-1 prepared by the emulsion-gel method.

Effect of Poly（Ether Urethane） Introduction on the Performance of Polymer Electrolyte for All-Solid-State Dye-Sensitized Solar Cells

The introduction of poly（ether urethane） （PEUR） into polymer electrolyte based on poly（ethylene oxide）, LiI and I2, has significantly increased the ionic conductivity by nearly two orders of magnitudes. An increment of I3- diffusion coefficient is also observed. All-solid-state dye-sensitized solar cells are constructed using the polymer electrolytes. It was found that PEUR incorporation has a beneficial effect on the enhancement of open circuit voltage VOC by shifting the band edge of TiO2 to a negative value. Scanningelectron microscope images indicate the perfect interfacial contact between the TiO2 electrode and the blend electrolyte.

A Study on Porosity Distribution in Nanoporous TiO2 Photoelectrodes for Output Performance of Dye-Sensitized Solar Cells

Porosity as one of the crucial factors to film morphology affects the overall electrical current-voltage characteristics of dye-sensitized solar cell （DSC）. We search for the short-circuit current density, the open-circuit voltage and the maximum power output as the main functional parameters of DSC closely related to porosity under different film thickness. The theoretical analyses show some exciting results. As porosity changes from 0.41 to 0.75, the short-circuit current density shows the optimal value when the film thickness is 8-10 μm. The open-circuit voltage presents different variation tendencies for the film thicknesses within 1-8 μm and within 10-30 μm. The porosity is near 0.41 and the film thickness is about 10 μm, DSC will have the maximum power output. The theoretical studies also illustrate that given a good porosity distribution, DSC can obtain an excellent short-circuit current characteristic, which agrees well with the experimental results reported in previous literature.

In/Pd-Doped SnO2-Based CO Micro-Structure Sensor with High Sensitivity and Quick Response

In/Pd-doped SnO2 is synthesized via a sol-gel method and coated on a silicon substrate with Pt electrodes to fabricate a micro-structure sensor. The sensor can be used to detect CO down to l ppm （the sensitivity is about 3）, and the response time and recovery time are about 5 and 15 s, respectively. Excellent selectivity is also found based on our sensor. These results demonstrate a promising approach to fabricate high-performance CO sensors with high sensitivity and quick response.

侏罗系油藏油井用固体缓蚀剂适用性研究

依据相关标准及模拟工况的腐蚀速率和电化学性能测试,对固体缓蚀剂的理化性能、缓蚀效果和缓蚀作用机理进行评价分析,探讨固体缓蚀剂在长庆油田侏罗系油藏开发过程中的适用性。研究结果表明,固体缓蚀剂具有良好的理化性能,在现场水介质中溶解性良好,并且无乳化倾向,但大量油相的存在会降低固体缓蚀剂的长期有效性;添加固体缓蚀剂后,在较短释放周期内,J55钢的均匀腐蚀速率明显下降,缓蚀效率高达85.64%;固体缓蚀剂长时间释放后,缓蚀作用明显减弱,其释放60 d后的缓蚀效率仅为7.37%;综合固体缓蚀剂均匀和局部腐蚀缓蚀性能以及释放率的测试结果,其投加周期不应超过60 d;固体缓蚀剂的电化学作用机理主要表现为阴极阻滞型缓蚀,但当固体缓蚀剂长时间释放后,J55钢的阳极过程明显活化,缓蚀剂吸附膜阻急剧减小,固体缓蚀剂的缓蚀效果显著降低。