Successive column correction algorithms for solving sparse nonlinear systems of equations

This paper presents two algorithms for solving sparse nonlinear systems of equations: the CM-successive column correction algorithm and a modified CM-successive column correction algorithm. Aq-superlinear convergence theorem and anr-convergence order estimate are given for both algorithms. Some numerical results and the detailed comparisons with some previously established algorithms show that the new algorithms have some promise of being very effective in practice.This research was partially supported by contracts and grants: DOE DE-AS05-82ER1-13016, AFOSR 85-0243 at Rice University, Houston, U.S.A. and Natural Sciences and Engineering Research Council of Canada grant A-8639.     

Reconstruction of the water-oxidizing complex in manganese-depleted Photosystem II using synthetic manganese complexes

The efficiency of a trinuclear and two binuclear manganese complexes in reconstituting electron transport and O(2) evolution activity in Mn-depleted Photosystem II preparations is analyzed. The trinuclear Mn-complex is more efficient than two binuclear Mn-complexes in restoring oxygen evolution, but it is less effective as an electron donor than binuclear Mn-complexes. It is inferred from our results that recovery of electron transport and O(2) evolution with polynuclear Mn-complexes is affected with different factors. Moreover, the trinuclear Mn-complex is extremely sensitive to the addition of CaCl(2). It is suggested that there is an interaction between Ca(2+) and carboxyl within the trinuclear Mn-complex during photoactivation and this interaction benefits the ligation of Mn atom to the apo-WOC and form an active WOC. Binuclear Mn(III)Mn(III) complex shows slightly higher efficiency than binuclear Mn(III)Mn(IV) complex in restoration of O(2) evolution activity. The efficiency of three Mn-complexes in the reconstitution of WOC is in an order: trinuclear Mn(3)(III)>binuclear Mn(III)Mn(III)>binuclear Mn(III)Mn(IV).     

酶提取-单颗粒电感耦合等离子质谱法分析樱桃番茄纳米银颗粒及其吸收规律研究

为探究复合保鲜涂膜中AgNPs的迁移情况,采用酶提取的前处理方式,结合单颗粒电感耦合等离子体质谱（SP-ICP-MS）,考察了前处理方式、驻留时间、校准方式以及Ag+浓度等条件对AgNPs准确测定的影响。结果表明：0.1 g樱桃番茄样品在柠檬酸盐体系下使用0.2 g的R-10离析酶可达到消解最适酶剂量;当驻留时间小于100 μs时,测定结果有较好的积分条件以及较高的信背比;采用AgNP尺寸方式进行校准比单独用Ag+标准溶液校准方式的颗粒尺寸测定结果更加准确。采用该方法测定樱桃番茄中加标AgNPs颗粒回收率达到88.9%,粒径实测值为47.8±0.3 nm,粒径检出限为13 nm,颗粒浓度检出限为 7.5×104 particles/L。通过将樱桃番茄暴露于AgNPs涂膜中来探究AgNPs迁移行为,复合保鲜涂膜后的樱桃番茄通过三次洗涤后能够在表面去除大部分AgNPs,但仍有少量AgNPs穿过果表皮浸入果肉组织。该方法灵敏度高,操作简单,能够为揭示AgNPs在农产品及农业生产中的风险提供可靠、准确的表征方法。     

Analysis of stability for a discrete ratio-dependent predator-prey system

The paper investigated the dynamical behaviors of a two-species discrete ratio-dependent predator-prey system. The local stability of the equilibria is obtained by using the linearization method. Further, a new sufficient condition on the global asymptotic stability of the positive equilibrium is established by using an iteration scheme and the comparison principle of difference equations.     

Formation of Cr(VI) compounds during the thermal decomposition of amorphous chromium hydroxide

Chromium hydroxide (CH) was prepared by the reduction of purified sodium chromate using starch. CH was then used to prepare chromium oxide (Cr₂O₃). Results of thermogravimetric, X-ray diffraction, Fourier transform infrared spectroscopy, and chemical analyses suggested that a small amount of the initial Cr(VI) content speeds up the oxidation and reduction reactions, thereby promoting the purity and crystallization of Cr₂O₃. Cr(VI) in CH induced the evolution of CH and the formation of Cr(VI) containing compounds including CrO₃, NaCr(CrO₄)₂, Cr₃O₈, and Cr₅O₁₂ at low sintering temperature. Furthermore, homogeneous Cr₂O₃ nanoparticles with 99 % purity and particle size of 50 nm were obtained.     

Achieving 16.68% efficiency ternary as-cast organic solar cells

State-of-the-art organic solar cells(OSCs)often require the use of high-boiling point additive or post-treatment such as temperature annealing and solvent vapor annealing to achieve the best efficiency.However,additives are not desirable in largescale industrial printing process,while post-treatment also increases the production cost.In this article,we report highly efficient ternary OSCs based on PM6:BTP-Cl Br1:BTP-2O-4Cl-C12(weight ratio=1:1:0.2),with 16.68%power conversion efficiency(PCE)for as-cast device,relatively close to its annealed counterpart(17.19%).Apart from obvious energy tuning effect and complementary absorption spectra,the improved PCE of ternary device is mainly attributed to improved morphological properties including the more favorable materials miscibility,crystallinity,domain size and vertical phase separation,which endorse suppressed recombination.The result of this work provides understanding and guidance for high-performance as-cast OSCs through the ternary strategy.     

Optimal extent of fluorination enabling strong temperature-dependent aggregation,favorable blend morphology and high-efficiency polymer solar cells

Temperature-dependent aggregation is a key property for some donor polymers to realize favorable bulk-heterojunction(BHJ)morphologies and high-efficiency(10%) polymer solar cells.Previous studies find that an important structural feature that enables such temperature-dependent aggregation property is the 2nd position branched alkyl chains sitting between two thiophene units.In this report,we demonstrate that an optimal extent of fluorination on the polymer backbone is a second essential structural feature that enables the strong temperature-dependent aggregation property.We compare the properties of three structurally similar polymers with 0,2 or 4 fluorine substitutions in each repeating unit through an in-depth morphological study.We show that the non-fluorinated polymer does not aggregate in solution(0.02 mg mL~(-1) in chlorobenzene) at room temperature,which results in poor polymer crystallinity and extremely large polymer domains.On the other hand,the polymer with four fluorine atoms in each repeating unit exhibits an excessively strong tendency to aggregate,which makes it difficult to process and causes a large domain.Only the polymer with two fluorine atoms in each repeating unit exhibits a suitable extent of temperature-dependent aggregation property.As a result,its blend film achieves a favorable morphology and high power conversion efficiency.This provides another key design rationale for developing donor polymers with suitable temperature-dependent aggregation properties and thus high performance.     

Facile synthesis of micron‐sized hollow copper spheres with ZSM‐5 molecular sieve as a template

A new, well‐designed type of micron‐sized hollow copper spheres was synthesized in this article. The process was performed using ZSM‐5 molecular sieve as a template. It has the prominent advantage in that the various stages of pretreatment for the core material can be omitted because of the inherent nature of the ZSM‐5 molecular sieve. The surface of the sieve consists entirely of negatively charged oxygen sites such that free Cu²⁺ ions can easily be adsorbed and reduced there, acting thereafter as a seed and self‐catalyst for electroless plating of copper so as to lead to the formation of interconnected Cu particles around the external surface of the ZSM‐5 molecular sieve. Moreover, there are many holes with a size of more than 5 × 5 Ų on the surface of the ZSM‐5 molecular sieve, which can act as concavities that the reduced Cu can ‘rivet’ into, resulting in the link between the molecular sieve and the reduced Cu being stronger. In addition, the ZSM‐5 molecular sieve has the merits of ease of removal, low cost, and less aggregation owing to its micrometer size, and it avoids the use of nonvolatile surfactants, which may be adsorbed onto the reduced Cu and then interfere with the possible application of the hollow copper spheres in catalysis and in analytical devices based on surface‐enhanced Raman scattering (SERS) spectroscopy. The copper spheres obtained show enhanced Raman scattering in the presence of adsorbed 4‐mercaptobenzoic acid (4‐MBA) with excitation at 632.8 nm, and the enhancement factor reaches ∼7 × 10³. The new micron‐sized hollow copper spheres are produced in a simple and cost‐effective method; so they are expected to play an important role in the fields of catalysts, fillers, and engineering, and in the development of SERS‐based analytical devices. The synthetic method may represent a novel route to prepare hollow metal spheres, which is a subject of intense interest. Copyright © 2009 John Wiley & Sons, Ltd.     

Enhanced electrochemical performance of LiNi0.8Co0.1Mn0.1O2 cathode via wet-chemical coating of MgO

Journal of Solid State Electrochemistry - LiNi0.8Co0.1Mn0.1O2 (NCM811) has a high potential for using as the cathode material for lithium–ion batteries (LIBs) for electric vehicles owing to...     

光合放氧复合物结构及其放氧机理的研究

光合水氧化是地球上最重要的生化过程之一.光合放氧生物包括光系统Ⅰ(PSⅠ)和光系统Ⅱ(PSⅡ)两种类型反应中心,光系统Ⅱ反应中心能以水作为电子给体,利用光能氧化水产生质子和氧气.对于水如何被氧化这个难题前人已做了大量的工作,但到目前为止放氧复合物(OEC)的结构及水氧化的机理仍不清楚.本文结合当前研究结果,就光合放氧复合物的结构及光合放氧机理进行了综述,希望能有助于推进这方面的工作.