Wurtzite MS nanorods were synthesized from coordination polymer M(tp)(4,4′-bipy)∞ at 140°C under solvothermal condition (M=Zn, Cd). The morphology determined by TEM gives the average diameters of ...width/length as 50/200 nm and 20/75 nm for ZnS and CdS, respectively. X-ray powder diffraction and XPS spectra proved that the as-prepared products were pure ZnS and CdS, respectively.
TiO(OH)2 sol and activated charcoal were mixed, hydrolysed and gelled at 60 C. Following drying, the gel was nitrided in a carbon tube furnace at 1400-1600 C in flowing nitrogen gas, to give TiC1-xNx ...(x = 0-1) ultrafine powders. The influence of temperature, C:Ti ratio in the raw materials, holding time and nitrogen flow rate were investigated. TiC0.5N0.5 powders with a particle size of less than 100 nm were produced at 1550 C, which when hot pressed at 1750 C had a microhardness of 19.6 GPa and a relative density of 98.9%. 16 refs.
Double-wall carbon nanotubes (DWCNTs) have been better prepared by thermally decomposing ferrocene mixed with sulphur in the mixture flows of argon and acetylene at 950–1150
°C. The product of DWCNTs ...has been systematically studied as a function of the reaction temperature, the partial pressure of hydrocarbon, the sublimed temperature of ferrocene, and the relative molar value of ferrocene to sulphur. Our efforts to optimize the catalyst composition by replacing the partial ferrocene with cobaltocene have been proved to be inappropriate. In this process, the role of sulphur on the preparation condition has also been discussed.
Evidence of ψ(3770) decays to a non-DD¯ final state is observed. A total of 11.8±4.8±1.3ψ(3770)→J/ψπ+π− events are obtained from a data sample of 27.7 pb−1 taken at center-of-mass energies around ...3.773 GeV using the BES-II detector at the BEPC. The branching fraction is determined to be BF(ψ(3770)→J/ψπ+π−)=(0.34±0.14±0.09)%, corresponding to the partial width of Γ(ψ(3770)→J/ψπ+π−)=(80±33±23) keV.
An epidemic of severe acute respiratory syndrome (SARS) has been associated with an outbreak of atypical pneumonia originating in Guangdong Province, People's Republic of China. We aimed to identify ...the causative agent in the Guangdong outbreak and describe the emergence and spread of the disease within the province.
We analysed epidemiological information and collected serum and nasopharyngeal aspirates from patients with SARS in Guangdong in mid-February, 2003. We did virus isolation, serological tests, and molecular assays to identify the causative agent.
SARS had been circulating in other cities of Guangdong Province for about 2 months before causing a major outbreak in Guangzhou, the province's capital. A novel coronavirus, SARS coronavirus (CoV), was isolated from specimens from three patients with SARS. Viral antigens were also directly detected in nasopharyngeal aspirates from these patients. 48 of 55 (87%) patients had antibodies to SARS CoV in their convalescent sera. Genetic analysis showed that the SARS CoV isolates from Guangzhou shared the same origin with those in other countries, and had a phylogenetic pathway that matched the spread of SARS to the other parts of the world.
SARS CoV is the infectious agent responsible for the epidemic outbreak of SARS in Guangdong. The virus isolated from patients in Guangdong is the prototype of the SARS CoV in other regions and countries.
Several mechanisms have been used to explain solar wind plasma entry into the plasma sheet in the magnetotail. In this paper, we focus on the gradient drift entry (GDE) process in the equatorial ...flanks of the magnetosphere, based on the magnetopause picture of a tangential discontinuity with a small tangential electric field as was suggested by Alfvén (1968). We discuss the GDE efficiency in different conditions using the adiabatic theory. It can be clearly shown that the GDE efficiency is much lower during southward interplanetary magnetic field (IMF), with a strong energy filter effect for incoming solar wind particles. Given a typical condition, a critical energy for particle entry is calculated to be several kiloelectron volts. Only those particles with higher energy can penetrate the magnetopause, a condition which can be also proved by test particle simulations. The lower efficiency than that during northward IMF during periods of southward IMF is in agreement with the different properties of the plasma sheet observed, i.e., hot and tenuous when the IMF is southward, cold and dense for northward IMF.
Neurotrophins have been shown to acutely modulate synaptic transmission in a variety of systems, but the underlying signaling mechanisms remain unclear. Here we provide evidence for an unusual ...mechanism that mediates synaptic potentiation at the neuromuscular junction (NMJ) induced by neurotrophin-3 (NT3), using Xenopus nerve-muscle co-culture. Unlike brain-derived neurotrophic factor (BDNF), which requires Ca2+influx for its acute effect, NT3 rapidly enhances spontaneous transmitter release at the developing NMJ even when Ca2+influx is completely blocked, suggesting that the NT3 effect is independent of extracellular Ca2+. Depletion of intracellular Ca2+stores, or blockade of inositol 1, 4, 5-trisphosphate (IP3) or ryanodine receptors, prevents the NT3-induced synaptic potentiation. Blockade of IP3 receptors can not prevent BDNF-induced potentiation, suggesting that BDNF and NT3 use different mechanisms to potentiate transmitter release. Inhibition of Ca2+/calmodulin-dependent kinase II (CaMKII) completely blocks the acute effect of NT3. Furthermore, the NT3-induced potentiation requires a continuous activation of CaMKII, because application of the CaMKII inhibitor KN62 reverses the previously established NT3 effect. Thus, NT3 potentiates neurotransmitter secretion by stimulating Ca2+release from intracellular stores through IP3 and/or ryanodine receptors, leading to an activation of CaMKII.
BES data on
J/
ψ→
γ(
K
+
K
−
π
+
π
−) are presented. The
K
∗
K
̄
∗
contribution peaks strongly near threshold. It is fitted with a broad 0
−+ resonance with mass
M=1800±100 MeV, width
Γ=500±200 MeV. ...A broad 2
++ resonance peaking at 2020 MeV is also required with width ∼500 MeV. There is further evidence for a 2
−+ component peaking at 2.55 GeV. The non-
K
∗
K
̄
∗
contribution is close to phase space; it peaks at 2.6 GeV and is very different from
K
∗
K
∗
̄
.
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