Trace measurements of rhodium by adsorptive stripping voltammetry

A sensitive stripping voltammetric procedure for quantifying rhodium is described. The complex of rhodium with chloride ions is adsorbed on the hanging mercury drop electrode, and the reduction current of the accumulated complex is measured during a negative-going scan. Cyclic voltammetry is used to characterize the interfacial and redox behaviors. The effect of pH, chloride concentration, accumulation potential and other variables is discussed. The detection limit is 1 x 10(-8)M ( approximately 1 ng/ml) with 5-min accumulation. A linear current-concentration relationship is observed up to 7 x 10(-7)M and the relative standard deviation (at the 2 x 10(-7)M level) is 3.0%. Possible interferences by co-existing metals are investigated.     

Cu(bpy)22+—Nafion聚合物膜修饰电极研究

在目前的聚合物膜修饰电极领域中引起人们极大的研究兴趣,这是因为用离子交换方法可将许多电化学或电催化活性的阳离子物种固定于Nafion膜中,构成具有离子导电功能和特定电化学性质的膜合物膜修饰电极。     

Synthesis and characterization of linear high molecular weight poly(amino-s-triazine)s

A two-phase polycondensation reaction was used to prepare high molecular weight linear poly-(amino-s-triazine)s from aminodichloro-s-triazines and diamines. These polymers contain a high concentration of melamine-type units in the polymer backbone. Molded specimens exhibited good mechanical properties and resistance to organic solvents. Dimethyl substitution at the exocyclic amino group led to a significant reduction in indentation resistance, strength, and modulus.     

Stripping voltammetry of thorium based on adsorptive accumulation

A sensitive stripping voltammetric procedure for quantifying thorium is described. The chelate of thorium with the azo dye Mordant Blue 9 is adsorbed on the hanging mercury drop electrode, and the reduction current of the accumulated chelate is measured during a negative-going potential scan. Cyclic voltammetry is used to characterize the interfacial and redox behaviors. The effects of pH, dye concentration and accumulation potential are discussed. The detection limit is 4 × 10^?10 M (4-min accumulation), a linear current-concentration relationship is observed up to 1.3 × 10^?7 M, and the relative standard deviation (at the 6 × 10^?8 M level) is 3.1%. Possible interferences by trace metals and organic surfactants are investigated. Simultaneous quantitation of thorium and nickel is illustrated.     

生物质裂解产物的制备及HPLC检测其成分的虚拟仿真实验开发

In order to improve university laboratory teaching and practical education under the background of information technology, as well as overcome the difficulty for practical training, develop a virtual simulation experiment platform for rapid pyrolysis of natal materials and high-performance liquid chromatographic (HPLC) detection of its components. The experiment integrates the actual operation process of the plant to produce cleaved products by rapid pyrolysis of biomass with HPLC detection. The virtual experiment is divided into biomass sample pretreatment, rapid biomass pyrolysis, bio-oil extraction, and HPLC determination of complex components, making the biomass cleavage workshop "real" through simulation. This virtual simulation experiment fully integrates the utilization of biomass resources and basic chemistry courses (such as organic chemistry, instrumental analysis, chemical engineering principles, etc.), which are widely involved in agricultural and forestry majors with advantageous characteristics value.     

“鱼”乐圈大揭秘

This article introduces the relationship between chemistry and fish farming, fish selling, and fish food. The nitrogen cycle process in fish ponds is introduced to explain the fish farming. "Yufuling" is used as the entry point to fish selling to connect food safety with chemistry. Fishy smell is explained from a chemical perspective for fish food. This paper aims at making a scientific explanation of life phenomena, deepening the consciousness of chemical life, helping people establish a correct view of chemical science, and inspiring youth to learn to use the knowledge that they have learned to explain life phenomena. This paper also tries to show the youth that life cannot be separated from chemistry, and chemistry cannot be separated from life.     

Extraction of thorium,uranium and cerium from fresh water using manganese dioxide coprecipitation

A manganese dioxide coprecipitation procedure is utilized to replace a time-consuming evaporation step for the extraction of thorium, uranium and cerium from freshwater samples. The average recovery for 20-liter samples is greater than 95% for²³⁴Th and¹⁴⁴Ce. The data indicate that the manganese dioxide coprecipitation process does not affect the recovery of thorium and uranium during our routine analytical procedure.     

A new Co(2)(CO8-mediated tandem [5 + 1]/[2 + 2 + 1]-cycloaddition reaction: a one-pot synthesis of tricyclic delta-lactones from cis-epoxy ene-ynes

In the presence of Co2(CO)8 and CO, cis-epoxyalkynes bearing a tether olefin undergo a tandem [5 + 1]/[2 + 2 + 1]-cycloaddition to give tricyclic delta-lactones efficiently in a one-pot operation. The reaction mechanism is proposed to involve a cobalt-coordinated cyclic allene species.     

Solving the 3-SAT problem based on DNA computing

The 3-SAT problem is an NP-complete problem, and many algorithms based on DNA computing have been proposed for solving it since Adleman's pioneering work. This paper presents a new algorithm based on the literal string strategy proposed by Sakamoto et al. Simulation results show that the maximal number of literal strings produced during the computing process is greatly reduced. Moreover, the length of the literal strings is also reduced from m to n at most.     

Competition in the bioreactor with general quadratic yields when one competitor produces a toxin

Microorganisms produce toxins against its competitors sometimes, and variable yields are useful to explain the observed oscillatory behavior in the reactor. In this paper, a model with general quadric yields of competition in the bioreactor of two competitors for a single nutrient where one of the competitors can produce toxin against its opponent, is proposed. We analyze the asymptotic behavior of the model in terms of the relevant parameters. The conditions of the three dimensional Hopf bifurcation, and the existence of limit cycles in the nutrient-organism phase plane are obtained.