RESULTS FROM THE SLD BARREL CRID DETECTOR

We report on operational experience with an experimental performance of the SLD barrel Cherenkov Ring Imaging Detector from the 1992 and 1993 physics runs. The liquid (C6F14) and gas (C5F12) radiator recirculation systems have performed well, and the drift gas supply system has operated successfully with TMAE for three years. Cherenkov rings have been observed from both the liquid and gas radiators. The number and angular resolution of Cherenkov photons have been measured, and found to be close to design specifications.

Determination of carbamate insecticides in apples, pears, and lettuce by LC with UV detector

A simple and rapid method was developed for determination of 8 carbamate insecticides and 10 of their metabolites in apples, pears, and lettuce by liquid chromatography with UV diode array detector. With this method no derivatization is needed. Carbamates not belonging to the N-methylcarbamate class and metabolites without the N-methyl group can also be determined.

Role of the surface state and structural feature in the thermoreversible sol-gel transition of a zirconyl aqueous precursor modified by sulfuric acid

The sols produced by admixture of ZrOCl2 acidified solutions to hot H2SO4 aqueous solutions were studied to clarify the effects of Cl- and SO42- ions on the kinetic stability of nanoparticles and to obtain some new evidence concerning the mechanism of a thermoreversible sol-gel transition observed in this system. The study of suspensions prepared with different molar ratios R-S = [Zr]/[SO42-] and R-Cl = [Zr]/[Cl-] revealed domains of composition of formation of thermoreversible gels, thermostable sols, and powder precipitation. The effects of R-S and R-Cl on the structural features of nanoparticles and on the particle solution interface were systematically analyzed for samples of thermoreversible and thermostable sol domains. Small-angle X-ray scattering measurements revealed the presence of small fractal aggregates in all samples of thermoreversible domains, while compact packing aggregates of primary particles are present in the thermostable sol. Extended X-ray absorption fine structure and elemental chemical analysis revealed that irrespective of the nominal value of R-S and R-Cl all studied samples of the thermoreversible domain are constituted by a well-defined compound possessing an inner core made of hydroxyl and oxo groups bridging together zirconium atoms surrounded on the surface by complexing sulfate ligands. zeta potentials of powders extracted by freeze-drying from the thermoreversible gel revealed a point of surface charge inversion attributed to the specific adsorption of SO42- ion. Thermoreversible gel formation is rationalized by considering the effect of the specific adsorption on the electrical double-layer repulsion together with the temperature dependency of the physical chemical properties of ions in solution.

Butanolides as a common feature of Iryanthera lancifolia and Virola surinamensis

A comparative phytochemical study between pericarps of Iryanthera lancifolia and Virola surinamensis showed that the first one contains a new pair of epimeric 2-alkenyl-gamma-lactones, besides an aryltetralinic lignan and one tocotrienol, while the second species contains the lignans, galgravin and veraguensin, seven juruenolides: juruenolides C, D, F, G and epi-juruenolides D, F, G, together with three pairs of epimeric aliphatic 2-alkenyl-gamma-lactones. Juruenolide F, epi-juruenolides D, F, G and the 2-alkenyl-gamma-lactones are new natural compounds. (C) 1998 Elsevier B.V. Ltd. All rights reserved.

THE FLUID SYSTEMS FOR THE SLD CHERENKOV RING IMAGING DETECTOR

We describe the design and operation of the fluid delivery, monitor and control systems for the SLD barrel Cherenkov Ring Imaging Detector (CRID). The systems deliver drift gas (C2H6+TMAE), radiator gas (C5F12+N2) and radiator liquid (C6F14). MeasUred critical quantities such as electron lifetime in the drift gas and ultra-violet (UV) transparencies of the radiator fluids, together with the operational experience, are also reported.

SnO2, ZnO and related polycrystalline compound semiconductors: An overview and review on the voltage-dependent resistance (non-ohmic) feature

The present review describes mainly the history of SnO2-based voltage-dependent resistors, discusses the main characteristics of these polycrystalline semiconductor systems and includes a direct comparison with traditional ZnO-based voltage-dependent resistor systems to establish the differences and similarities, giving details of the basic physical principles involved with the non-ohmic properties in both polycrystalline systems. As an overview, the text also undertakes the main difficulties involved in processing SnO2- and ZnO-based non-ohmic systems, with an evaluation of the contribution of the dopants to the electronic properties and to the final microstructure and consequently to the system's non-ohmic behavior. However, since there are at least two review texts regarding ZnO-based systems [Levinson, L. M., and Philipp, H. R. Ceramic Bulletin 1985;64:639; Clarke, D. R. Journal of American Ceramic Society 1999;82:485], the main focus of the present text is dedicated to the SnO2-based varistor systems, although the basic physical principles described in the text are universally useful in the context of dense polycrystalline devices. However, the readers must be careful of how the microstructure heterogeneity and grain-boundary chemistry are capable to interfere in the global electrical response for particular systems. New perspectives for applications, commercialization and degradation studies involving SnO2-based polycrystalline non-ohmic systems are also outlined, including recent technological developments. Finally, at the end of this review a brief section is particularly dedicated to the presentation and discussions about others emerging non-ohmic polycrystalline ceramic devices (particularly based on perovskite ceramics) which must be deeply studied in the years to come, specially because some of these systems present combined high dielectric and non-ohmic properties. From both scientific and technological point of view these perovskite systems are quite interesting. (c) 2007 Elsevier Ltd. All rights reserved.

The dielectric suppress and the control of semiconductor non-Ohmic feature of CaCu3Ti4O12 by means of tin doping

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for the flavor-changing neutral current decay Bs 0 → μ+ μ- pp̄ Collisions at √s = 1.96 TeV with the DO Detector

We present the results of a search for the flavor-changing neutral current decay Bs 0 → μ+ μ-. using a data set with integrated luminosity of 240 pb-1 of pp̄ collisions at √s = 1.96 TeV collected with the D0 detector in run II of the Fermilab Tevatron collider. We find the upper limit on the branching fraction to be B(Bs 0 → μ+ π-) ≤ 5.0 × 10-7 at the 95% C.L. assuming no contributions from the decay Bd 0 → μ+ μ- in the signal region. This limit is the most stringent upper bound on the branching fraction Bs 0 → μ+ μ- to date. © 2005 The American Physical Society.

Frequency-adjustable positive sequence detector for power conditioning applications

This paper proposes a novel and simple positive sequence detector (PSD), which is inherently self-adjustable to fundamental frequency deviations by means of a software-based PLL (Phase Locked Loop). Since the proposed positive sequence detector is not based on Fortescue's classical decomposition and no special input filtering is needed, its dynamic response may be as fast as one fundamental cycle. The digital PLL ensures that the positive sequence components can be calculated even under distorted waveform conditions and fundamental frequency deviations. For the purpose of validating the proposed models, the positive sequence detector has been implemented in a PC-based Power Quality Monitor and experimental results illustrate its good performance. The PSD algorithm has also been evaluated in the control loop of a Series Active Filter and simulation results demonstrate its effectiveness in a closed-loop system. Moreover, considering single-phase applications, this paper also proposes a general single-phase PLL and a Fundamental Wave Detector (FWD) immune to frequency variations and waveform distortions. © 2005 IEEE.

Strategies for developing NADH detector based on meldola blue in different immobilization methods: A comparative study

A comparative study was accomplished between two immobilization methodologies for the meldola's blue (MB), used to decrease the oxidation potential of NADH. The study was performed with glassy carbon electrode by electropolymerization of pyrrole and MB through the technique of cyclic voltammetry being evaluated the effect of the number of cycles to define the thickness and the stability of the film. With 25 cycles it was obtained the best result. They were also investigated the modification of the graphite electrode with film formed by the system sol-gel PPO 300 or PPO 4000 for the dip-coating, through two methods: occlusion and adsorption. The best method was it of adsorption of MB during 10 min, following by deposit of the film PPO 300, favored for the time of drying (24 hours). The adsorption of MB followed by PPO 300 deposition presented broader linear range than PPy methodology. ©2006 Sociedade Brasileira de Química.

Search for decay of a fermiophobic higgs boson hf→ y y with the D0 detector at s=1.96a TeV

We report the results of a search for a narrow resonance decaying into two photons in 1.1fb-1 of data collected by the D0 experiment at the Fermilab Tevatron Collider during the period 20022006. We find no evidence for such a resonance and set a lower limit on the mass of a fermiophobic Higgs boson of mhf>100GeV at the 95% C.L. This exclusion limit exceeds those obtained in previous searches at the Fermilab Tevatron and covers a significant region of the parameter space B(hf→I I ) vs mhf which was not accessible at the CERN Large Electron-Positron Collider. © 2008 The American Physical Society.