黄河河口镇至龙门区间洪水特性分析

通过对黄河河口镇至龙门区间近 40年的实测水文资料 ,对黄河龙门水文站发生的 Q>60 0 0 m3 /s的 75场次洪水 (按照不同流量级别 )进行了统计分析。得出了河龙区间 Q>60 0 0 m3 /s的洪水来源、基本组成 ,年内分配以及区间内不同区段洪水的遭遇等基本特性。研究河龙区间洪水的基本特性 ,对于提高该区间洪水测验精度和黄河下游的防汛有着重要的意义     

Effect of two ethnic processing technologies on reduction and composition of total and non-glucosidic cyanogens in cassava

The effectiveness of two different processing methods on reduction of total and non-glucosidic cyanogens in cassava was studied in two ethnic groups in Nkhota Kota, Malawi. Cassava cyanogen content was periodically monitored during processing. Total cyanogen reductions of 97.9 ± 0.5% and 82.4 ± 1.0% were obtained upon soaking peeled and unpeeled roots, respectively. The residual cyanogen content (2.6 ± 0.7 mg HCN eq./kg) in flour produced from peeled roots was lower than the FAO/WHO limit (10 mg HCN eq./kg). The flour from the unpeeled method contained twenty times more residual cyanogen levels (53.8 ± 1.8 mg HCN eq./kg dry matter). The peels exhibited four times higher cyanohydrin than the pulp. Inclusion of the peel during processing therefore leads to high retention of cyanogens in the pulp. Clearly, soaking of peeled roots is a more effective method and thus should be promoted among ethnic communities that soak unpeeled roots.     

4-[(1H-imidazol-4-yl) methyl] benzamidines and benzylamidines: novel antagonists of the histamine H3 receptor

A series of amidine substituted phenyl-, benzyl-, and phenethylimidazoles based on the known H3 agonist SK&F 91606 (4) has been synthesized and tested as ligands for the histamine H3 receptor. Insertion of a phenyl ring between the imidazole ring and the amidine moiety produces antagonists. The benzyl series was found to be the most potent and was further investigated. Compounds 9c and 18 (entries 5 and 12, Table 1) are potent ligands for the H3 receptor with K(i) values of 16 nM and 7.2 nM respectively. In vivo, both compounds were shown to be equipotent to thioperamide (2), the standard H3 antagonist.     

Effect of Stoichiometric Reductants on the Process of Ferrochrome Production at 1200–1550°C

Metallurgist - Ferrochrome alloys are mainly produced in submerged-arc furnaces. Reductants used in ferrochrome production include coke, anthracite, and char. However, it is still unclear what...     

钨Ⅵ-5′-硝基水杨基荧光酮-CTMAB体系显色反应及其分析应用

研究了钨与 5′-硝基水杨基荧光酮 -溴化十六烷基三甲基铵体系的显色反应。结果表明 ,在 0.2 4～ 0.78mol/L盐酸介质中 ,W 与 5′ 硝基水杨基荧光酮生成桔红色络合物 ,其最大吸收波长为 5 2 2nm ,Δλ =5 4nm ,表观摩尔吸光系数为 1.5 8× 10 5,测定的线性范围为 0～ 13 μg/2 5mL ,本方法用于合金钢中钨的测定 ,结果满意     

Study of physicochemical parameters and spontaneous fermentation during traditional production of munkoyo, an indigenous beverage produced in Democratic Republic of Congo

The evolution of physicochemical parameters and spontaneous fermentation were investigated during traditional production of munkoyo. During munkoyo preparation, starch hydrolysis by amylolytic enzymes contained in munkoyo roots was performed at temperatures above 43 °C. After 90 h, pH decreased from 6.4-6.2 to 3.7-3.6; lactic acid concentration and acidity increased respectively from 4.4-15.0 mmol l⁻¹ to 42.0-44.0 mmol l⁻¹ and 0.05% to 0.45-0.6%; alcohol content did not exceed 394 mmol l⁻¹. When the temperature dropped from 43-42 °C to 29-25 °C, in the first 15 h of fermentation, the rate of pH decrease was significant, from 6.4-6.2 to 4.1-4.0. The acidification of munkoyo was due to lactic acid, largely in the form of the d (−) lactate isomer. At temperatures around 20 °C, secondary products also contributed to the acidification of the beverage. Lactic fermentation, observed from 43 °C in the wort, was promoted by thermophilic lactic acid bacteria. Lactobacillus delbrueckii lactis was identified as the representative lactic acid bacteria. Alcohol production in munkoyo, beginning only after 15 h of fermentation, is due mainly to Saccharomyces cerevisiae.     

Information Overload,Similarity, and Redundancy: Unsubscribing Information Sources on Twitter

The emergence of social media has changed individuals' information consumption patterns. The purpose of this study is to explore the role of information overload, similarity, and redundancy in unsubscribing information sources from users' information repertoires. In doing so, we randomly selected nearly 7,500 ego networks on Twitter and tracked their activities in 2 waves. A multilevel logistic regression model was deployed to test our hypotheses. Results revealed that individuals (egos) obtain information by following a group of stable users (alters). An ego's likelihood of unfollowing alters is negatively associated with their information similarity, but is positively associated with both information overload and redundancy. Furthermore, relational factors can modify the impact of information redundancy on unfollowing.     

Application of Knelson Concentrator for Beneficiation of Copper–Cobalt Ore Tailings

The beneficiation of high talc-containing copper–cobalt flotation tailings was studied by centrifugal gravity concentration. It was found that copper and cobalt minerals were finely disseminated in the gangue matrix so that conventional gravity concentration using spirals and shaking tables would be ineffective. The actual experimental test work was performed using the Knelson gravity concentrator and the results were transposed to industrial scale by simulating several beneficiation scenarios. The results indicated that integration of Knelson concentrators in the concentration circuit to treat the flotation tailings would significantly improve copper and cobalt recoveries from 65.00% to 86.09% and 67.00% to 86.96%, respectively.