A solvent extraction technique for the isotopic measurement of dissolved copper in seawater

Stable copper (Cu) isotope geochemistry provides a new perspective for investigating and understanding Cu speciation and biogeochemical Cu cycling in seawater. In this work, sample preparation for isotopic analysis employed solvent-extraction with amino pyrollidine dithiocarbamate/diethyl dithiocarbamate (APDC/DDC), coupled with a nitric acid back-extraction, to concentrate Cu from seawater. This was followed by Cu-purification using anion-exchange. This straightforward technique is high yielding and fractionation free for Cu and allows precise measurement of the seawater Cu isotopic composition using multi-collector inductively coupled plasma mass-spectrometry. A deep-sea profile measured in the oligotrophic north Tasman Sea shows fractionation in the Cu isotopic signature in the photic zone but is relatively homogenised at depth. A minima in the Cu isotopic profile correlates with the chlorophyll a maximum at the site. These results indicate that a range of processes are likely to fractionate stable Cu isotopes in seawater.     

Structural and electrical properties of polyvinyl alcohol (PVA):Methyl cellulose (MC) based solid polymer blend electrolytes inserted with sodium iodide (NaI) salt

This paper studies the structural and electrical properties of solid polymer blend electrolytes based on polyvinyl alcohol (PVA) and methylcellulose (MC) incorporated with sodium iodide (NaI). The polymer electrolyte films were assembled through a solution casting technique. The host matrix, which is doped with different NaI salt concentrations between 10 and 50 wt%, utilizes the most amorphous blend compositions (60 wt% Polyvinyl alcohol and 40 wt% methylcellulose). The structural behaviour of the electrolyte films was examined utilizing X-ray diffraction (XRD) and Fourier transformation infrared (FTIR) techniques. The semi crystalline nature of PVA:MC with inserted NaI was derived from the X-ray diffraction studies, while the XRD analysis suggests that the highest ion conductive sample displays the minimum crystalline nature. The interaction between polymer blends and inserted salt was conceived from the FTIR investigation. Shifting of peaks and variation in the intensity of FTIR bands was detected. To investigate the structural properties and calculate the degree of crystallinity of the films, the (XRD) technique was employed, while electrical impedance spectroscopy (EIS) was utilized for studying the conductivity of the samples. In order to comprehend all of the electrical properties of the ion-conducting systems, the EIS outcome of each electrolyte was matched with Equivalent Electrical Circuits (EEC) s. Ion transport parameters including mobility, carrier density and diffusion are well assessed for the samples and the dielectric properties were compared with the conductivity measurement. At lower frequencies, the dielectric constant was elevated and dielectric loss was detected. Loss tangent and electric modulus plots were used to study the relaxation nature of the samples. The highest ambient temperature conductivity of PVA loaded 50 wt% of NaI was determined to be 1.53 × 10⁻⁵ S/cm. The loss tangent relaxation peak shifts towards high-frequency side which indicates the decrease of relaxation time and faster ion dynamics.     

Development of a gas chromatographic/mass spectrometric method to quantify R(-)-apomorphine, R(-)-apocodeine and R(-)-norapomorphine in human plasma and urine

A method was developed and validated for the analysis of R(-)-apomorphine, (R-)-apocodeine and R(-)-norapomorphine in human plasma and urine with N-propylnorapomorphine as internal standard using gas chromatography/mass spectrometry (GC/MS) and single-ion monitoring after a single liquid-liquid extraction and silylation of compounds. The quantification limits were 1 ng/ml for apomorphine and apocodeine and 25 ng/ml for norapomorphine. Calibration curves were linear, within the range 1-100 ng/ml. Variation in intraday and interday precision was below 10%. This method was applied to study apomorphine bioavailability in nine patients with Parkinson's disease before and after coadministration of a catechol-O-methyl transferase inhibitor.     

Structure formation in monolayers composed of hard bent-core molecules

ABSTRACT

We investigate the role of excluded volume interactions instabilising different structures in monolayers filled with bent-shaped molecules using the Onsager type of density functional theory supplemented by constant-pressure Monte-Carlo simulations. We study influence of molecular features, like the apex angle, thickness of the arm and the type of the arm edges on the stability of layered structures. For simple molecular shapes taken the observed phases are dominated by the lamellar antiferroelectric type as observed experimentally, but a considerable sensitivity of the ordering to details of the molecular shape is found for order parameters and wave vectors of the structures. Interestingly, for large opening angles and not too thick molecules, a window of stable nematic splay-bend phase is shown to exist.     

基于MC2833P的小功率调频发信机的设计

MC2833P是MOTOROLA公司为无绳电话和调频通信设备而生产的调制发射子系统芯片。它内含话筒放大器、电压控制振荡器和两个辅助晶体管。可用于小功率调制发射机及无绳电话等方面。文中介绍了MC2833P的功能结构和主要参数，指出了它的应用要点和无线特性。最后给出了MC2833P的应用电路。     

Molecular MC SCF calculations by direct minimization

Calculations on the H₂CO ground state and excited states at the equilibrium planar geometry, using the single excitation MC SCF method, are described for two basis sets. The results obtained by a full calculation including all the electrons are compared with those obtained by a pseudopotential version of the method including only the valence electrons. The results agree quite well both with each other and with the observed values.     

80C196MC波形发生器和智能功率模块在逆变器中的应用

利用Intel公司的80C196MC片内波形发生器可简化产生MWM波形的软、硬件设计，而三菱公司的PM100CSA120智能功能模块则是将功率器件、驱动电路和保护逻辑电路集于一身的智能型功能模块，将这两种器件用于逆变电路中可大大简化系统设计并提高系统的可靠性。文中中给出了利用PM100CSA120和80C196MC简化系统设计的电路结构。     

碳纳米管对MC尼龙6结晶行为的影响

通过甲苯二异氰酸酯(TDI)改性多壁羟基碳纳米管并用已内酰胺封端,采用单体浇铸的方法制备MC尼龙6、改性碳纳米管纳米复合材料.红外光谱(FTIR)结果证明TDI改性后碳纳米管上成功接有异氰酸酯基团.X射线衍射(XRD)结果表明,改性碳纳米管的加入没有改变MC尼龙6结晶的品型结构;而未改性碳纳米管的加入则抑制了其α2晶的...     

基于MC68HC908RF2的无线温度传感器

针对不能直接布线的旋转设备的温度检测问题,设计了一款低成本、微功耗的无线温度传感器.详细阐述了实现方法和设计要点,对系统中采用的关键元器件进行了介绍,给出了系统的硬件结构及软件流程图.设计中充分利用了各芯片的低功耗特性,有效地延长了电池的使用时间.实验证明,此传感器具有良好的可靠性和性价比,有广阔的应用前景.