Altering the rate-determining step over cobalt single clusters leading to highly efficient ammonia synthesis

Activation of high-energy triple-bonds of N₂ is the most significant bottleneck of ammonia synthesis under ambient conditions. Here, by importing cobalt single clusters as strong electron-donating promoter into the catalyst, the rate-determining step of ammonia synthesis is altered to the subsequent proton addition so that the barrier of N₂ dissociation can be successfully overcome. As revealed by density functional theory calculations, the N₂ dissociation becomes exothermic over the cobalt single cluster upon the strong electron backdonation from metal to the N₂ antibonding orbitals. The energy barrier of the positively shifted rate-determining step is also greatly reduced. At the same time, advanced sampling molecular dynamics simulations indicate a barrier-less process of the N₂ approaching the active sites that greatly facilitates the mass transfer. With suitable thermodynamic and dynamic property, a high ammonia yield rate of 76.2 μg h^–1 mg and superior Faradaic efficiency of 52.9% were simultaneously achieved.     

电解法去除高浓度氨氮废水工艺研究

本文采用电解技术对高浓度氨氮废水进行处理研究,考察电化学方法对废水中高浓度氨氮的去除效果,并优化其工艺参数。结果表明,电流密度、Cl^-1浓度、极板对数等均对高浓度氨氮的电解处理效率有直接影响;综合考虑电耗、投加Cl^-1量等经济因素和处理效果,其优化工艺参数为8A电流、NH4^＋与Cl^-1的摩尔比为1：4、2对极板;此条件下氨氮的90m in去除率为81.5%,电耗为63.6度。     

Effect of CO2 enrichment on the glucosinolate contents under different nitrogen levels in bolting stem of Chinese kale (Brassica alboglabra L.)

The effects of CO₂ enrichment on the growth and glucosinolate (GS) concentrations in the bolting stem of Chinese kale (Brassica alboglabra L.) treated with three nitrogen (N) concentrations (5, 10, and 20 mmol/L) were investigated. Height, stem thickness, and dry weights of the total aerial parts, bolting stems, and roots, as well as the root to shoot ratio, significantly increased as CO₂ concentration was elevated from 350 to 800 μl/L at each N concentration. In the edible part of the bolting stem, 11 individual GSs were identified, including 7 aliphatic and 4 indolyl GSs. GS concentration was affected by the elevated CO₂ concentration, N concentration, and CO₂×N interaction. At 5 and 10 mmol N/L, the concentrations of aliphatic GSs and total GSs significantly increased, whereas those of indolyl GSs were not affected, by elevated atmospheric CO₂. However, at 20 mmol N/L, elevated CO₂ had no significant effects on the concentrations of total GSs and total indolyl GSs, but the concentrations of total aliphatic GSs significantly increased. Moreover, the bolting stem carbon (C) content increased, whereas the N and sulfur (S) contents decreased under elevated CO₂ concentration in the three N treatments, resulting in changes in the C/N and N/S ratios. Also the C/N ratio is not a reliable predictor of change of GS concentration, while the changes in N and S contents and the N/S ratio at the elevated CO₂ concentration may influence the GS concentration in Chinese kale bolting stems. The results demonstrate that high nitrogen supply is beneficial for the growth of Chinese kale, but not for the GS concentration in bolting stems, under elevated CO₂ condition. Project (No. 2007CB109305) supported by the National Basic Research Program (973) of China     

富春江（富阳段）表层沉积物中生源物质的分布特征

针对富春江(富阳段)水污染现状,对富春江(富阳段)的洋浦、永济浦和大源溪三个主要排污口附近的沉积物进行系统研究。结果表明,受污染沉积物的有机质含量为41.6～294.2g/kg,平均为145.3g/kg;凯氏氮含量为1.2～5.2g/kg,平均为2.6g/kg;总磷含量为817-1415μg/g,平均为1050μg/g。沉积物有机质、总氮、总磷水平对研究区底栖生物群落和生态环境构成了较大威胁。沉积物的有机质和凯氏氮含量受排污口影响明显;但沉积物总磷含量受排污口影响不明显。生源物质之间以及生源物质与沉积物理化性质的相关性分析表明,沉积物碳、氮以及粉砂粒存在同源性,沉积物磷与碳、氮以及粉砂粒不具有同源性,关于该区域磷素污染源还需进一步调研确认。     

补充糖和肌酸对艺术体操运动员定量负荷后血糖、血清CK和BUN值的影响

采用实验法,按正交表L4(23)进行实验设计,探讨补充糖、肌酸对艺术体操运动员血糖、血乳酸、血尿素氮和血清肌酸激酶活性影响的效果.结果表明,单独补充糖或肌酸、同时补充糖和肌酸均可使运动员赛后血糖、血尿素氮和血清肌酸激酶活性显著下降,而且、糖和肌酸同时补充效果更好,有利于提高艺术体操运动员竞技能力.     

复混肥料中总氮含量的测定

采用半微量蒸馏装置测氮的方法 ,对复混肥料中总氮含量进行测定 ,具有准确度高、平行性好、检测速度快等特点 ,有很高的实用价值     

辽东地区土壤全氮含量的测定及其分析

分析土壤全氮及其各种形态氮的含量是评价土壤肥力和合理使用氮肥的主要依据．本试验对辽东地区土壤全氮含量的分析结果表明,全氮含量从高到低的顺序依次为：草河口,牦牛坞,五龙背,合隆,刘家河．对全氮含量较低的地区应适当提高氮肥的使用来改善土壤的肥力．     

一种新的高速重氮感光剂的合成

本文报道合成了一种高效重氮盐，在关键的一步以对苯二酚为原料合成对苯二丁醚的反应中，应用了相转移催化法，研究了催化剂种类对产率的影响．同时对反应时间对产率的影响也进行了考察、初步得出了对苯二酚正丁基化的最佳条件．目标分子的生成中，对中间体胺分离出来后，立即重氮化，同时加入氯化锌使之生成稳定的复盐，收到了很好的效果．     

小氮肥厂脱硫工艺及其优化选择的探讨

本文简述了原料气中的硫化物对合成氨生产的危害。在分析以天然气为原料的小氮肥厂常用脱硫剂的脱硫原理和对比脱硫工艺的基础上,并以绵阳南光化工总厂氮肥分厂脱硫工艺改造为例,阐明了常温可再生氧化铁脱硫与锰铁锌系脱硫的联合脱硫新工艺为首推优化选择。     

高产小麦需肥规律和氮素"M"型追肥法效应分析

高产小麦吸收氮素规律呈现"M"型,两个高峰出现在分蘖期和拔节期,磷和钾吸收量随生育进程逐步平稳增加,高峰出现在中后期。生产上,高产小麦氮素追肥应采取"前轻(分蘖轻)后重(拔节一孕穗重)中控(越冬-拔节期控)"的"M"型追肥法。