The electrochemistry of zirconium in aqueous solutions at elevated temperatures and pressures

The electrochemistry of zirconium has been explored in borate buffer solution of pH = 6.94 at 250 °C with and without hydrogen by measuring the current, impedance, and capacitance as a function of potential. Data are interpreted in terms of modified point defect models (PDM) that recognize the existence of a thick oxide outer layer over a thin barrier layer. From thermodynamic analysis, it is postulated that a hydride barrier layer forms under PWR coolant conditions whereas an oxide barrier layer forms under BWR primary coolant conditions. Thus, the introduction of hydrogen into the solution lowers the corrosion potential of zirconium to the extent that the formation of ZrH₂ is predicted to be spontaneous rather than the ZrO₂. Mott–Schottky analysis shows that the passive film formed on zirconium is n-type, which is consistent with the PDM, corresponding to a preponderance of oxygen/hydrogen vacancies and/or zirconium interstitials in the barrier layer.     

Antibacterial effect of phenolic compounds from different wines

The antimicrobial properties of pure phenolic compounds and polyphenols of different wines against pathogens were investigated. It was observed that bacterial species exhibited different sensitivities towards the different concentrations of phenolic compounds. Escherichia coli was the most sensitive bacterium and Flavobacterium sp. was resistant against all phenolic compounds tested. All wine samples showed antimicrobial properties and the inhibition increased when the polyphenols concentration of wines increased. Clarified wines were inactive against all bacteria, indicating that polyphenolic compounds present in red wines, are responsible for the antimicrobial effects observed. The different concentrations of polyphenols in wines could have an important impact on consumers with the consequent increase in wine commercialization.     

An approach to the generalized nurse scheduling problem--generation of a declarative program to represent institution-specific knowledge.

An approach to the nurse scheduling problem is presented. The critical problem in nurse scheduling in a hospital is how to determine the day-to-day shift assignments of each nurse for a specified period in a way that satisfies the given requirements as much as possible, where the requirements differ greatly depending on the hospital. We present a method for constructing an agency-independent core procedure which can be tailored to the peculiar requirements of an individual hospital. As a basis, a formal analysis of the problem was performed, and a general scheduling procedure was established. Based on the method, a software system which produces a scheduling program for a given institution was developed. A declarative program that represents institution-specific information is generated through an interview with the user and incorporated into the general procedure. Some of the programming technicalities and an application of the system are also presented.     

A Web-based flood forecasting system for Shuangpai region

Traditional flood forecasting and operation of reservoirs in China are based on manual calculations by hydrologists or through standalone computer programs. The main drawbacks of these methods are long forecasting time due to time-consuming nature, individual knowledge, lack of communication, absence of experts, etc. A Web-based flood forecasting system (WFFS), which includes five main modules: real-time rainfall data conversion, model-driven hydrologic forecasting, model calibration, precipitation forecasting, and flood analysis, is presented in this paper. The WFFS brings significant convenience to personnel engaged in flood forecasting and control and allows real-time contribution of a wide range of experts at other spatial locations in times of emergency. The conceptual framework and detailed components of the proposed WFFS, which employs a multi-tiered architecture, are illustrated. Multi-tiered architecture offers great flexibility, portability, reusability and reliability. The prototype WFFS has been developed in Java programming language and applied in Shuangpai region with a satisfactory result.     

Small volume PCR in PDMS biochips with integrated fluid control and vapour barrier

In this paper we demonstrate a new method for microfabricating PDMS devices that controls vapour diffusion, thereby reducing water loss at elevated temperatures and greatly increasing the reliability of the PCR. In the past, the vapour and liquid diffusion properties of the PDMS material in microfluidic devices have impaired performance. We show that this water loss is primarily due to vapour diffusion from the PDMS biochip and by implanting a polyethylene vapour barrier layer in the PDMS, the overall fluid loss was almost eliminated (reduced by a factor of 3). We have also developed a procedure to ensure irreversible bonding between the PDMS and the implant. With this improved microfabrication method we demonstrate the feasibility and advantages of performing small volume PCR genetic amplification (i.e. with less than 2 μl of PCR sample) within a PDMS–glass hybrid biochip. Diaphragm pumps and pinch-off valves were integrated in the system and these enabled fluid retention during the amplification stage and will facilitate higher levels of on-chip automation.     

Response kinetics of temperature-independent resistive oxygen sensor formulations: a comparative study

This contribution compares the response kinetics of two temperature-independent resistive oxygen sensor formulations: LaCu_0.3Fe_0.7O_3−δ (LCF) and La_0.05Sr_0.95Ti_0.65Fe_0.35O_3−δ (LSTF). Screen-printed thick film sensor specimens were prepared. Sensor characteristics towards oxygen were determined, and additional measurements in the frequency domain were realized: the former indicate a fast and nearly temperature-independent response of LCF and LSTF compositions in the temperature range between 750 and 900 °C. The latter allow conclusions on the underlying sensing mechanism. Whereas oxygen sensitivity of LSTF is exclusively controlled by a reaction step, response of LCF is governed by reaction only at lower temperatures. At higher temperatures, a diffusion process becomes limiting. This different behavior is attributed to different microstructures of the sensitive films.     

Elastic and optical properties of BeS,BeSe and BeTe under pressure

We have performed the first principles full-potential linearized augmented plane wave calculations (FP-LAPW) with density functional theory in local density approximations (LDA), in aim to determine and to predict the pressure dependence of structural and optical properties of zinc-blende BeS, BeSe and BeTe compounds. The elastic constant, refractive index and its variation with hydrostatic pressure are well described.     

Study of fuel insolubles: Formation conditions and characterization of copper compounds

The solids formed in the systems containing copper in different oxidation states, in the presence and absence of hexanoic acid and dodecanethiol, together and separately, at room temperature, were studied. The experiments were performed in a mineral oil matrix, free of sulfur compounds and metals; a diesel oil matrix; and the reagents alone, without any matrix. The deposits formed were analyzed by elemental analysis (EA), infrared spectroscopy (IR), thermogravimetric analysis (TGA) and total copper by inductively coupled plasma-optical emission spectrometry (ICP-OES), for their identification and determination of the probable structures. In samples containing both hexanoic acid and dodecanethiol, when there is copper(I), anhydrous copper(II) hexanoate is preferentially formed, but in samples of copper(II), copper(II) mercaptate is formed first. In samples of metallic copper in mineral oil matrix, no deposit formations occur. In all cases in which deposits were formed, they were the same as in diesel oil matrix.     

Effects of washing with oxidising agents on the gel-forming ability and physicochemical properties of surimi produced from bigeye snapper (Priacanthus tayenus)

The effects of washing with hydrogen peroxide (H₂O₂) and sodium hypochlorite (NaOCl) solutions on the gel-forming ability and physicochemical properties of surimi produced from bigeye snapper (Priacanthus tayenus), stored in ice for up to 14 days, were investigated. Generally, pH and the trichloroacetic acid (TCA)-soluble peptide content of washed mince varied, depending on the type of oxidizing agent and storage time of the fish. With increasing time of storage, the pHs of water- and H₂O₂-washed mince were lower than that of NaOCl-washed mince (P < 0.05). However, no differences in the TCA-soluble peptide contents of the resulting mince washed with any media were observed (P > 0.05). Washing with 20 ppm NaOCl resulted in the highest increase in both the breaking force and the deformation of mince from fish stored in ice for all the times studied (P < 0.05). Natural actomyosin (NAM) extracted from NaOCl-washed mince had higher surface hydrophobicity and disulfide bond (SS) content than that of water-washed mince (P < 0.05). With no effect on Ca²⁺-, Mg²⁺-, or Mg²⁺–Ca²⁺-ATPase activities, NaOCl washing resulted in an increase in Mg²⁺–EGTA-ATPase activity of NAM (P < 0.05). The results suggested that washing mince with the appropriate type and concentration of oxidizing agent can improve the gelling ability of surimi, particularly from low quality fish.     

Molecular imprinting strategy for solvent molecules and its application for QCM-based VOC vapor sensing

Cross-linked polymers made of methyl methacrylate (MMA) as a monomer and divinylbenzene (DVB) as a cross-linking agent were prepared in the presence of toluene or p-xylene as a solvent. The cross-linked polymer prepared in toluene tended to sorb toluene vapor preferably, while the cross-linked polymer prepared in p-xylene sorbed p-xylene vapor preferably. The observed molecular recognition ability can be explained on the bases of an imprinting effect by solvent molecules. Molecularly imprinted polymer (MIP) powders were blended with PMMA, and the blended films were coated on a piezoelectric quartz crystal with a view to preparing QCM-based VOC sensors. The imprint effect was clearly observed, even in these blended films. The response of the sensor towards toluene or p-xylene vapor was reversible; however, the response time was slow due to the existence of the matrix polymer around the MIP particles.