Spinel LiMn₂ ₋ ₓCoₓO₄ (0.00 ≦ x ≦ 0.20) powders with small and uniform particle size were successfully synthesized by microwave-induced combustion using lithium nitrate, manganese nitrate, cobalt ...nitrate, and urea as the starting materials. The LiMn₂ ₋ ₓCoₓO₄ powders synthesized by microwave-induced combustion were investigated by X-ray diffractometer (XRD), thermogravimeter analyzer (TG), and scanning electron microscopy (SEM). The LiMn₂ ₋ ₓCoₓO₄ samples were used as cathode materials in lithium-ion batteries, whose discharge capacity and electrochemical characteristics such as the cycling performance were also investigated. The results revealed that the LiMn₂ ₋ ₓCoₓO₄ cell synthesized by microwave-induced combustion provided a high initial capacity and excellent reversibility compared to the material prepared by solid-state reaction method.
Electron paramagnetic resonance imaging (EPRI) using nitroxides is an emergent imaging method for studying in vivo physiology, including O(2) distribution in various tissues. Such imaging ...capabilities would allow O(2) mapping in tumors and in different brain regions following hypoxia or drug abuse. We have recently demonstrated that the anion of 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxyl (2) can be entrapped in brain tissue to quantitate O(2) concentration in vivo. To increase the sensitivity of O(2) measurement by EPR imaging, we synthesized 3-carboxy-2,2,5,5-tetra((2)H(3))methyl-1-(3,4,4-(2)H(3),1-(15)N)pyrrolidinyloxyl (7). EPR spectroscopic measurements demonstrate that this fully isotopically substituted nitroxide markedly improves signal-to-noise ratio and, therefore, the sensitivity of EPR imaging. The new isotopically substituted nitroxide shows increased sensitivity to changes in O(2) concentration, which will enable more accurate O(2) measurement in tissues using EPRI.
A laboratory-based surveillance network of 11 clinical virological laboratories for influenza viruses was established in Taiwan under the coordination of the Center for Disease Control and Prevention ...(CDC), Taiwan. From October 2000 to March 2004, 3,244 influenza viruses were isolated, including 1,969 influenza A and 1,275 influenza B viruses. The influenza infections usually occurred frequently in winter in the northern hemisphere. However, the influenza seasonality in Taiwan was not clear during the four seasons under investigation. For example, the influenza A viruses peaked during the winters of 2001, 2002, and 2003. However, some isolated peaks were also found in the summer and fall (June to November) of 2001 and 2002. An unusual peak of influenza B also occurred in the summer of 2002 (June to August). Phylogenetic analysis shows that influenza A isolates from the same year were often grouped together. However, influenza B isolates from the year 2002 clustered into different groups, and the data indicate that both B/Victoria/2/87-like and B/Yamagata/16/88-like lineages of influenza B viruses were cocirculating. Sequence comparison of epidemic strains versus vaccine strains shows that many vaccine-like Taiwanese strains were circulating at least 2 years before the vaccine strains were introduced. No clear seasonality of influenza reports in Taiwan occurred in contrast to other more continental regions.
Abstract
Different bacterial community profiles were observed on the soft coral Dendronephthya sp. and an inanimate reference site using terminal restriction fragment length polymorphism analysis of ...bacterial community DNA. To correlate the observation with a chemical defense mechanism against bacterial epibiosis, antibacterial effects of coral tissue extracts and waterborne products of coral-associated bacterial isolates (11 morphotypes) were tested against indigenous benthic bacterial isolates (33 morphotypes) obtained in the vicinity of the coral colonies. The coral tissue extracts and waterborne products of coral-associated bacteria inhibited growth and attachment of indigenous bacterial isolates, suggesting an endogenous chemical and an exogenous biological mechanism against bacterial epibiosis in this soft coral.
A low-volume submersible drift-pump unit is described for the collection of demersally drifting biota, particularly for shallow aquatic situations. This unit collects less motile biota quantitatively ...(so far zooplankton, larvae of macrofauna, and meiofauna are successfully collected). It can easily be modified for the sampling of a variety of other aquatic organisms, in particular nano- and picoplankton (algal, bacterial, fungal and viral plankton) at high temporal and spatial resolution. A new drift-net unit allows qualitative comparisons of demersally drifting invertebrates. Both light-weighted stationary systems can be modified for sampling at varying distances from the bottom and are suggested for fine-scale appliances at moderate depths from shore, pier, boat, or deployed by divers.
It is known that the peptide corresponding to the N‐terminal β‐hairpin of ubiquitin, U(1–17), can populate the monomeric β‐hairpin conformation in aqueous solution. In this study, we show that the ...Gly‐10 that forms the bulge of the β‐turn in this hairpin is very important to the stability of the hairpin. The deletion of this residue to desG10(1–16) unfolds the structure of the peptide in water. Even under denaturing conditions, this bulge appears to be important in maintaining the residual structure of ubiquitin, which involves tertiary interactions within the sequence 1 to 34 in the denatured state. We surmise that this residual structure functions as one of the nucleation centers in the folding process and is important in stabilizing the transition state. In accordance with this idea, deleting Gly‐10 slows down the refolding and unfolding rate by about one half.
This work divided into two parts. The first part reports the characteristics of a La0.8Ca0.2CoO3−δ (LCCO) cathode including its chemical bulk diffusion coefficient (Dchem) and chemical surface ...exchange coefficient (kchem) measured by an electrical conductivity relaxation (ECR) technique. The second part reports two methods to improve the performance of solid oxide fuel cells (SOFCs). One is the use of composite cathode, i.e., mixture of 30wt% electrolyte and 70wt% cathode. The other is the use of electrolyte-infiltrated cathode, i.e., the active ionic-conductive electrolyte with nanosize was infiltrated onto a porous cathode surface. In this work, the 0.2M Ce0.8Sm0.2O1.9 (SDC)-infiltrated La0.8Ca0.2CoO3−δ (LCCO) reveals the maximum peak power density of 305mWcm−2 at operating temperature of 800°C with a thin film SDC electrolyte (30μm), a Ni+SDC anode (1mm) and a SDC-infiltrated LCCO cathode (20μm). The enhancement in electrochemical performances by using the electrolyte-infiltrated cathode is ascribed to the creation of electrolyte/cathode phase boundaries, which considerably increase the electrochemical sites for oxygen reduction reaction. Therefore, the infiltrated method is a potential way to improve the performance of SOFCs.
An aqueous tape casting of gadolinia-doped ceria (GDC) ceramics was developed using Poly(acrylic acid) PAA as dispersant, Poly(vinyl alcohol) PVA as binder, Poly(ethylene glycol) PEG as plasticizer, ...and deionized water as solvent. Surface properties of GDC powder with and without PAA dispersant were characterized by electrokinetic measurements. The zeta potential measurement revealed that the isoelectric point for GDC powders in the absence of dispersant corresponds to a pH value of 4.06. The experimental results showed that pH value greatly affects the rheology of the slurry. Homogeneous, smooth, and defect-free green tapes were successfully obtained by using an appropriate slurry formula. Moreover, the crystallization kinetics of GDC powders prepared by coprecipitation process also has been investigated in this study. The activation energy of crystallization was calculated by differential scanning calorimetry (DSC) at different heating rates. Analysis of non-isothermal DSC data presented values of 105.3
kJ/mol and 1.171 for the activation energy of crystallization presented and the Avrami exponent, respectively.
Acid treatment, with aqueous solutions of HCl, HNO3, H2SO4, HNO3 + NaCl and H2SO4 + NaCl, for the amorphous reaction paste resulted from mesoporous anatase particles dispersed in KOH solution at ...90 °C has been performed. The alkaline reaction paste transforms into hexatitanate after addition of HCl solution (0.1 M) to a pH value from 6.0 to 12.0, but into TiO2-B at pH 1.2. Different phase changes are observed when a HNO3 or H2SO4 solution is used. Anatase starts to appear at pH 9.0 for HNO3 and at 12.0 for H2SO4 and persists down to pH 1.2. Besides, in the pH range studied, no other crystal phase is detected. The particle morphology of the TiO2-B and anatase produced at pH 1.2, using HCl, HNO3 or H2SO4 solution, is nanowire, with a width of ∼10 nm. Although NO3− or SO42− alone in the pH 1.2 solution favors anatase phase, co-existence Cl− leads to TiO2-B formation. Cl− plays a role dominating the formation of hexatitanate, which is then transformed into TiO2-B. However the particle morphology is affected due to the adsorption of NO3− and SO42−. The mechanism for the process from hexatitanate to TiO2-B, not relating to the anion nature, and the anion effect based on the binding manner and strength of the anions to titanium ions are discussed.
► Mesoporous anatase in KOH solution at 90 °C decomposes into amorphous paste. ► The paste can be transformed to fibrous anatase or TiO2-B by mixing with inorganic acids. ► HCl causes the formation of TiO2-B at pH 1.2 and hexatitanate at pH 6.0–12.0. ► H2SO4 and HNO3 solutions cause the formation of anatase. ► H2SO4 and HNO3 solutions in the presence NaCl at pH 1.2 produce TiO2-B.
PDF
