Analysis of total nitrogen and total phosphorus in soil using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy(LIBS) is used to determine the total nitrogen(TN) and total phosphorus(TP) in soil.Quantitative determinations are conducted using the line intensity of the analyte element and element concentration.Calibration models are obtained using ten samples for TN and seven samples for TP.The rest samples are used to validate the results.Strong linear correlations are obtained from the determined TN and TP concentrations.LIBS is a powerful tool for analyzing soil samples to determine nutrient elements by selecting calibration and validation samples with similar matrix composition.     

Fixed-time disturbance observer-based robust fault-tolerant tracking control for uncertain quadrotor UAV subject to input delay

Nonlinear Dynamics - This study focuses on the design of a fixed-time disturbance observer-based robust fault-tolerant tracking control scheme for an uncertain quadrotor unmanned aerial vehicle...     

Methylation pattern analysis using high-throughput microarray of solid-phase hyperbranched rolling circle amplification products

Monitoring the methylation pattern of a single tumor cell might be important in understanding the mechanism of tumor initiation and progression. In this study, we developed a method based on molecular cloning microarray strategy for analyzing methylation patterns of a single DNA fragment from a group of tumor cells. In the method, a microarray of single monoclones of bisulfate-treated PCR products was fabricated by two-primer hyperbranched rolling circle amplification (HRCA) in polyacrylamide gel, in which a library of the bisulfate-treated PCR products with different methylated status from tumor cells were ligated to circle molecules to form HRCA templates, and one of the HRCA primers was modified with acrylamide on its 5'-end. Due to the diffusion retardation of HRCA products in a polyacrylamide matrix, the HRCA products are localized near their respective templates, and formed to a microarray of monoclones. After the nonimmobilized strands were removed, three pairs of probes were used to detect different CpG sites of each clone simultaneously by hybridization. We successfully analyzed the methylation patterns of P16 gene for three cases of stomach tumor tissues. This method could provide a significant tool in detecting the distribution of cells with different methylation patterns in one tumor tissue.     

长江经济带城市竞争力评价及其空间分布

城市竞争力反映了一个城市的总体发展水平。采用《2014年中国城市统计年鉴》和各省市统计年鉴以及相关数据,对长江经济带35个地级以上主要城市分别选取19个评价指标,并通过因子分析法进行定量分析,得出了各自竞争力的评价排名结果及其空间分布。研究结果表明,长江经济带内部存在显著的城市之间发展不协调现象,有必要采取积极有效的措施,促进其协调发展,提升整体经济水平。为此,必须构建统一开放的全流域现代化市场体系;多维度发挥长江经济带与"一带一路"的空间协同效应;建设立体交通走廊,打造长江黄金水道;提高文化软实力等。     

一类具混合变元的一阶中立型微分方程的解振动的充要条件

考虑一阶中立型方程 ., 云[z(￡) 舻(c—r)] qx(c十f)一0,其中尹、q、f均为实常数,r>0,t>0. 方程(1)的特征方程是 △ ,(A)=A ?Ze一。 qe“=0. 引理1 方程(1)的所有解部振动的允要条件是特征方程(2)无实根[引.§l q>0的情形(2) 引理2特征方程(2)无实根的允要条件是对任意实数A有,(A)>0. 证明 充分性显然成立.只要证必要性,假如对任意实数A,,(A)>0不真,则有实数Ao,使,(A0)<0,而J.(0)一q>0,故在0与扎之M必仃,(A)一0的实根,矛盾. 定理I 方程(】)所有解振动的必要条件是p<0. 证明 只要证p≥0时方程(1)至少有一个非振动解.事实上,当p≥0时,l…     

土壤中砷元素的激光诱导击穿光谱测量分析

利用Nd:YAG脉冲激光器作为光源,在实验室自然大气环境下诱导产生国家标准土壤的激光等离子体,选取砷的228.8nm特征谱线作为分析线,测量并分析了砷元素的激光诱导击穿光谱特性。在相同含量和积分时间条件下,调节延迟时间,获取了砷元素的时间演化特性。确定砷元素的最佳延迟时间为1μs,积分时间为2μs。测定不同含量下,砷的特征谱线强度,给出砷元素的定标曲线,并计算得到砷元素的检测限为45mg/kg。     

沸石咪唑酯骨架材料用于水中污染物的去除

当前水污染问题严重制约了国民经济和社会的发展,对水污染的控制与治理具有重大研究意义且刻不容缓。沸石咪唑酯骨架结构材料（zeolitic imidazolate frameworks,ZIFs）作为新兴化学与材料科学相结合产物,凭借其结构稳定、比表面积大和性能优良等特点在全球范围内受到广泛关注,并逐步应用于去除水中的污染物。本文以ZIF-8为代表,综述沸石咪唑酯骨架材料去除水中污染物的研究与进展,系统介绍了其作为吸附剂及光催化剂对水中污染物的去除效果,总结了ZIFs制备条件和环境因素对其去除水中污染物的影响,并对今后的研究进行了展望,以期为ZIFs材料应用于实际污染水体的处理提供理论支撑。     

Synthesis of Al-SBA-15 and Its Application in Cobalt Based Fischer–Tropsch Synthesis

Kinetics and Catalysis - Three types of Al-SBA-15 were synthesized with vapor induced internal hydrolysis, impregnation and template methods and then utilized as supports for 15 wt % Co...