COREX工艺中还原气体成分对铁矿石还原性能的影响

本文根据试验研究结果，阐述了ＣＯＲＥＸ熔融还原工艺中还原气体成分对铁矿石还原度及金属化率的影响，还就该工艺中氧气浓度的问题进行了讨论。

基于CLR的玻璃文物成分分析与分类模型

对具有成分数据特征的古代玻璃成分数据集进行风化前成分含量预测以及类别划分.首先,对成分数据进行中心对数比变换预处理,从“成分相对重要性”的角度提取了成分数据的信息,并通过对变换后的玻璃文物化学成分数据分析:一方面,实现了对已风化的铅钡和高钾两类玻璃风化前化学成分的预测,即成分还原;另一方面,在铅钡和高钾两大类的基础上,拣选出可用于对玻璃文物进一步分出亚类的化学成分,构建了稳健的玻璃亚类分类模型.该模型可以实现在风化导致玻璃文物偏移其原始化学成分的情况下,对玻璃的亚类有大致正确的判断,即对风化文物原始成分的预测偏差不会显著影响分类结果.

氢基竖炉最佳开炉条件的数值模拟研究

利用组分输运模型对不同孔隙度、入口温度、H2含量条件下氢基竖炉开炉5 h的升温情况进行了模拟研究。结果表明,当还原气体组分及入口温度保持不变时,随着孔隙度的增大,炉内中心温度总体呈现升高的趋势;当孔隙度与入口温度保持不变时,炉内中心温度随着还原气体中氢气含量的增高而降低;当孔隙度与还原气体成分保持不变时,炉内中心点温度随着入口温度的上升而升高。氢基竖炉的最佳开炉条件为孔隙率0.40~0.42、还原气体中H_(2)和CO体积占比为40%和60%、入口温度1173 K。

汉语新词语分析法探析

改革开放以来,新词语大量涌现,对新词语的研究逐渐形成了百家争鸣的繁荣景象。与新词语在语言研究领域的成果相比,在对外汉语教学领域的研究尚显滞后,诸多方面还有待于进一步的深入与拓展。尤其是有关教学方法的探讨还处于起步阶段,仍需丰富与完善。本文主要列举了词源背景分析、简缩成分还原、同族系列理解、修辞形象分析等方法,以有效提高新词语在对外汉语教学中的教学效果。

UV-B辐射诱导芒果叶片抗氧化响应研究

为了解增强UV-B辐射诱导芒果叶片抗氧化响应的机制,以‘台农1号’芒果(Mangifera indica‘Tainong No.1’)成年树为材料,以自然光为对照(CK),设置24和96 kJ/(m^2·d)两个增强UV-B辐射处理水平,观测叶片生理生化指标的动态变化。结果表明,24 kJ/(m^2·d)处理的芒果叶片MDA含量、相对电导率、净光合速率、抗氧化酶活性、多酚、Vc和芒果苷含量均与对照没有显著差异,而类黄酮和还原型GSH含量显著高于对照;而96 kJ/(m^2·d)处理的芒果叶片MDA含量、相对电导率、抗氧化酶活性及多酚、类黄酮、还原型GSH、芒果苷等还原型保护成分的含量均显著高于对照,而净光合速率和Vc含量均显著低于对照。因此,24 kJ/(m^2·d)UV-B辐射未引起‘台农1号’芒果成年树损伤,可能是通过提高类黄酮和还原型GSH的含量来清除活性氧自由基;96 kJ/(m^2·d)处理则引起叶片活性氧损伤,但仍可能以两种机制减轻损伤,一是通过增强抗氧化酶活性和提高还原性成分含量来清除活性氧自由基,二是利用芒果苷、类黄酮和还原型GSH等成分吸收UV-B辐射。

TG–FTIR analysis of pyrolusite reduction by major biomass components

Pyrolusite reduction processes by three major biomass components cellulose,hemicelluloses and lignin,represented by CP,HP and LP,respectively,were investigated by thermogravimetric analyzer coupled with Fourier transform infrared spectrometry(TG-FTIR).The Sestak-Berggren(SB) equation was used to evaluate the kinetics of reduction processes.TG analysis reveals that the main reduction processes occur at 250-410 ℃,220-390 ℃,and 190-410 ℃ for CP,HP,and LP,respectively.FT-IR and XRD results indicate that various reducing volatiles(e.g.aldehydes,furans,ketones and alcohols) are produced from the pyrolysis with the three major components,which directly reduce MnO_2 in ore to MnO.The processes are described by the SB equation with three parameters(m,n,p).Their non-zero values suggest that pyrolusite reduction is controlled by the diffusion of reducing gaseous products through an ash/inert layer associated with minerals.The apparent activation energies for pyrolusite reduction by CP,HP and LP are 40.48,25.70 and 40.10 kJ·mol^(-1),respectively.

Dynamic model for predicting nitrogen oxide concentration at outlet of selective catalytic reduction denitrification system based on kernel extreme learning machine

To solve the increasing model complexity due to several input variables and large correlations under variable load conditions,a dynamic modeling method combining a kernel extreme learning machine(KELM)and principal component analysis(PCA)was proposed and applied to the prediction of nitrogen oxide(NO_(x))concentration at the outlet of a selective catalytic reduction(SCR)denitrification system.First,PCA is applied to the feature information extraction of input data,and the current and previous sequence values of the extracted information are used as the inputs of the KELM model to reflect the dynamic characteristics of the NO_(x)concentration at the SCR outlet.Then,the model takes the historical data of the NO_(x)concentration at the SCR outlet as the model input to improve its accuracy.Finally,an optimization algorithm is used to determine the optimal parameters of the model.Compared with the Gaussian process regression,long short-term memory,and convolutional neural network models,the prediction errors are reduced by approximately 78.4%,67.6%,and 59.3%,respectively.The results indicate that the proposed dynamic model structure is reliable and can accurately predict NO_(x)concentrations at the outlet of the SCR system.

多花少籽果中的醛糖还原酶抑制成分多花少籽果苷Ⅲ、Ⅳ、Ⅴ的结构

在研究天然药物抗糖尿病成分的过程中,发现一种巴西天然药物桃金娘科植物多花少籽果(Mvrcia multiflora)叶的甲醇提取物及其溶于乙酸乙酯的部分具有抑制醛糖还原酶、α-葡糖苷酶活性及降低蔗糖负荷大鼠和四氧嘧啶诱发的糖尿病小鼠血糖水平的作用。多花少籽果在南美国家广泛用作糖尿病特殊治疗药物,被称为植物胰岛素。

Chemical constituents from Portulaca oleracea and their bioactivities

In the present study, we aimed to intensively study the chemical constituents, especially organic acids from a medicinal plant Portulaca oleracea L., and screen their anti-inflammatory and quinone reductase （QR, a phase II detoxyfication enzyme） inductive activity. A total of 20 compounds were isolated and identified based on spectroscopic methods, as succinic acid （1）, mono-methyl succinate （2）, L-malic acid （3）, L-l-methyl malate （4）, L-4-methyl malate （5）, L-dimethyl malate （6）, L-6-ethyl citrate （7）, L-1-methyl citrate （8）, L-1,5-dimethyl citrate （9）, 4-hydroxy-5-methylfuran-3-carboxylic acid （10）, 5-hydroxymethyl-furoic acid （11）, stearic acid （12）, L-pyroglutamic acid （13）, cyclo-（tyrosine-leucine） （14）, L-isoleucine （15）, （-）-dehydrovomifoliol （16）, （-）-epiloliolide （17）, 3,4-dihydroxyphenylethanol （18）, succinimide （19）, and uracil （20）. Among them, 14 compounds （2, 4-8, 10, 11, 13-18） were isolated from P. oleracea for the first time. Compotmd 18 （12.5 μM） exhibited potent anti-inflammatory effect in lipopolysaccharide （LPS）-induced macrophage cells （RAW264.7） by reducing NO production, and it also increased QR activity in Hepa lclc7 cells. Compound 16 （50 μM） showed weak QR inductive activity. None of other compounds showed anti-inflammatory or QR inductive activities.

Distribution, Morphology, and Chemical Composition of Fe-Mn Nodules in Albeluvisols of the Carpathian Foothills, Poland

Iron and manganese oxides are common components of soils. They frequently occur in nodules constituting important soil sorbents and play a crucial role in a number of chemical reactions in the soil environment. In addition, the oxides are very sensitive to environmental changes (moisture, pH, Eh) constituting important indicators of soil-forming processes and water movement in the landscape. The objectives of the study were: i) to examine the distribution and size of Fe-Mn nodules in Albeluvisols containing a fragipan horizon; ii) to determine the morphology and chemical composition of the nodules, and iii) to estimate the effect of the fragipan horizon on water movement within the soil profile. An investigation was carried out on five soil profiles containing a fragipan horizon and classified as Fragic Albeluvisols within the Carpathian Foothills in Poland. In the Albeluvisols studied, the maximum concentration of Fe-Mn nodules occurred in the horizon lying directly on the fragipan horizon. This suggests that the pan acts as a natural barrier restricting water infiltration and leads to the seasonal development of a perched water table promoting redox processes. The most common are coarse (1-0.5 mm) and medium (0.5-0.25 mm) irregular Fe-Mn nodules showing a gradual boundary and undifferentiated internal fabric. Eluvial horizons contained also larger amounts of round and dense nodules with a sharp boundary, suggesting frequent oxidation and reduction. The fragipan horizon contained mainly irregular and soft nodules, suggesting longer saturation with water during the year. Concentrations of trace elements (Cu, Zn) and P were higher within Fe-Mn nodules than in the surrounding soil materials, showing that iron and manganese oxides adsorbed and immobilised these elements.

Rare earth element and yttrium compositions of the Paleoproterozoic Yuanjiacun BIF in the Lüliang area and their implications for the Great Oxidation Event(GOE)

In China, most Precambrian banded iron formations （BIFs） are situated in the North China Craton. The Yuanjiacun iron depos- it, located in the Ltlliang area, is arguably the most representative Superior-type BIF. This iron deposit is coherent with the sedimentary rock succession of the Yuanjiacun Formation in the lower Lliliang Group, and was interpreted to be deposited at 2.3-2.1 Ga, based on ages of overlying and underlying volcanic strata. This age overlaps with the time range of the Great Oxidation Event （GOE, 2.4-2.2 Ga）. The Yuanjiacun BIF consists mainly of subhedral-xenomorphic magnetite and quartz and rarely other minerals with a lower degree of metamorphism, from greenschist to lower amphibolite facies. The geochemical characteristics of this BIF are similar to those of Superior-type BIFs. Prominent positive La, Y, and Eu anomalies normalized by the Post Archean Australian Shale （PAAS） indicate that the primary chemical precipitate is a result of solutions that repre- sent mixtures of seawater and high-T hydrothermal fluids. The contamination from crustal detritus found is negligible based on low abundances of Al2O3 and TiO2 （〈0.5%） and of trace elements such as Th, Hf, Zr, and Sc （〈1.5 ppm）, as well as the lack of co-variations between Al2O3 and TiO2. In particular, the Yuanjiacun BIF samples do not display significant negative Ce anom- alies like those of the Archean iron formations, but rather, the Yuanjiacun BIF samples exhibit prominent positive Ce anoma- lies, low Y/Ho ratios, and high light to heavy REE （（Pr/Yb）sN） ratios, which are essentially consistent with the late Paleoprote- rozoic （〈2.0 Ga） BIFs around the world. These characteristics of the Yuanjiacun BIF samples imply that the ancient ocean （2.3-2.1 Ga） was redox-stratified from oxic shallow water to deeper anoxic water. The specific redox conditions of the ancient ocean may be related to the GOE, which gave rise to the oxidation of Ce and Mn in the upper water, and to the presence of a Mn oxide shuttle in the ocean, resulting in varying REE patterns due to the precipitation and dissolution of this Mn oxide shut tle under different redox states. Therefore, the Yuanjiacun BIF appears to have formed near the redoxcline and lower-level reduced marine water.

Synthesis of ultra-small mordenite zeolite nanoparticles

The mordenite（MOR） nanoparticles（MNPs）with ultra-small crystallites（~30 nm） were synthesized by using tetraethylammonium bromide（TEAB） as structure directing agent at low temperature（403K）. The formation of MNPs was considered to be due to high concentration of TEAB and occurrence of limiting Ostwald ripening at low temperature. The MNPs exhibited not only higher catalytic activity at low temperature for selective catalytic reduction of NOx but also higher catalytic activity and longer lifetime for disproportionation of toluene than conventional MOR（cMOR） bulk crystals.

A facile synthesis of 2-aryloxypyrimidine derivatives via a tandem reductive amination/intermolecular S_NAr sequence

A novel tandem reductive amination/intermolecular nucleophilic aromatic substitution (SNAr) sequence has been established for the synthesis of amine containing pyrimidine in formation of one carbon-oxygen and one carbon-nitrogen bonds in a one-pot fashion. Treatment of aldehyde with arylamine, 2-methanesulfonyl-4,6-dimeth-oxypyrimidine and sodium borohydride provides good overall yield. The p-toluenesulfonic acid (PTSA) can be used as activator and is generally needed in the reaction. Dioxane is the preferred reaction solvent, but reactions can also be carried out in tetrahydrofuran (THF), MeCN, toluene and dichloromethane. The procedure is carried out effectively in the presence of K2CO3. The reaction proceeds smoothly with aromatic aldehydes and arylamines possessing elec-tron-donating or-withdrawing groups. This method can be applied to the synthesis of the oilseed rape herbicide and is superior to the classical one in several aspects: cutting out several purification steps, minimizing solvent use and chemical waste, and saving time. Its advantages such as operational convenience, high-efficient synthesis, and starting material availability make it a desirable method for preparing amines with molecular diversity and biological activity.

Size-tunable synthesis of gold nanorods using pyrogallol as a reducing agent

A novel and facile seed-mediated method for the preparation of monodispersed gold nanorods(GNRs) is presented by introducing pyrogallol as a reductant. Fast Fourier transformation of high-resolution transmission electron microscopy reveals that the synthesized GNRs are single crystalline. The longitudinal surface plasmon resonance of GNRs can be finely tuned by varying silver ion concentrations or seed amounts. Also, both thick(diameter >30 nm) and thin(diameter <10 nm) GNRs with exceptional monodispersity can be well prepared by this method. These findings indicate that this method has a greater performance in controlling the morphology of GNRs than that of traditional approach with ascorbic acid as a reductant.