236 research outputs found
恶性黑色素瘤合并嗜肺军团菌感染性肺炎病例报告
Legionella pneumonia is mainly in community-acquired and nosocomial pneumonias caused by the L. pneumophila. The paper reported a case of Legionella pneumonia caused by Legionella pneumophila Sg1 in a man with malignant melanoma. The method for diagnosing Legionella pneumonia by standard culture method,serotyping,PCR-enzymatic digestion analysis and gene sequencing was elaborate. To confirm the diagnosis result of this rapid diagnostic method, sequencing of the bacteria in patient’s sputum partial gene was also carried out. The diagnosis result of this rapid diagnostic method was consistent with the culture method which indicated that it was effective in diagnosing L. pneumophila infection.军团菌肺炎主要是由嗜肺军团菌感染引起的一种社区获得性或医院内感染性肺炎。本文报告了1例临床上极为罕见的恶性黑色素瘤合并嗜肺军团菌血清1型感染引起的军团菌肺炎,并对其实验室诊断作了系统描述,包括病人痰液标本的细菌分离培养、血清学分型、PCR-酶切分型和基因测序鉴定等分子生物学诊断技术,结果表明PCR-酶切分型对于诊断军团菌病是一种快速、准确可靠的试验方法
One new cucurbitane triterpenoid from the fruits of Momordica charantia
One new cucurbitane triterpenoid commonly named neokuguaglucoside, together with three known compounds momordicoside M, momordicoside N, and momordicoside A were isolated from the fresh fruits of Momordica charantia. The new one's structure with an interesting sugar-like groups attached to the side chain was elucidated by spectroscopic analysis and semiepirical (AM1) quantum chemical method
Quasi-two-body decays in the perturbative QCD
In this work, we investigate the quasi-two-body decays with using the perturbative QCD(PQCD)
approach. The description of final state interactions between the pair
is achieved through the two-meson distribution amplitudes(DAs), which are
normalized to the time-like form factor. The PQCD predictions on the branching
ratios of the quasi-two-body decays show an obvious
hierarchy: and .
From the invariant mass -dependence of the decay spectrum for each
channel, one can find that the branching fraction is concentrated in a narrow
region around the pole mass. So one can obtain the branching ratios for
the corresponding two-body decays under the narrow width
approximation. We find that the branching ratios of the decays
are consistent well with the previous PQCD calculations within errors. These
predictions will be tested by the future experiments.Comment: 12 pages, 3 figures, accepted for publication in Chin. Phys.
Evidence of Hadronic Emission from the brightest-of-all-time GRB 221009A
Acceleration of hadrons in relativistic shocks has been long expected and
invoked to model GRB high-energy photon and neutrino emissions. However, so far
there has been no direct observational evidence of hadronic emission from GRBs.
The B.O.A.T. ("brightest of all time") gamma-ray burst (GRB) 221009A had
extreme energies (with an isotropic energy exceeding erg) and was
detected in broad-band including the very-high-energy (VHE, )
band up to TeV. Here we perform a comprehensive spectral analysis of the
GRB from keV to TeV energy range and perform detailed spectral and light curve
modelings considering both the traditional synchrotron self-Compton process and
the electromagnetic (EM) cascade process initiated by hadronic interactions by
accelerated cosmic rays in the external shock. We find that the leptonic
scenario alone is not adequate to account for the observations, whereas the
proposed scenario with the combination of hadronic and leptonic components can
well reproduce the multi-wavelength spectra and the light curve. This result
reveals the existence of the accelerated hadronic component in the early
afterglow of this extreme burst. According to this scenario, the observed TeV
light curve should contain imprints of the prompt MeV emission.Comment: 15 pages, 4 figures, 3 tables. originally submitted version for
Nature Astronom
Supramolecular assemblies constructed from inverted cucurbit[7]uril and lanthanide cations: synthesis, structure and sorption properties
The interaction of a series of lanthanide cations (Ln³⁺) with inverted cucurbit[7]uril (iQ[7]) in the presence of [ZnCl₄]²⁻ anions as a structure-directing agent have been investigated. Single-crystal X-ray diffraction analysis has revealed that the [ZnCl₄]²⁻ anions surround the iQ[7] molecules via the outer surface interactions of iQ[7]. This results in the formation of honeycomb-like frameworks, and ultimately linear supramolecular chains of iQ[7] in which Ln³⁺ cations occupy voids within the framework. Moreover, these iQ[7]/Ln³⁺-based supramolecular assemblies exhibit excellent thermal stability as well as permanent porosity, and in one case screening revealed a high CH₃OH uptake capacity compared with other porous organic materials assembled solely through hydrogen bonding under ambient conditions
STGC3 inhibits xenograft tumor growth of nasopharyngeal carcinoma cells by altering the expression of proteins associated with apoptosis
STGC3 is a potential tumor suppressor that inhibits the growth of the nasopharyngeal carcinoma cell line CNE2; the expression of this protein is reduced in nasopharyngeal carcinoma compared with normal nasopharyngeal tissue. In this study, we investigated the tumor-suppressing activity of STGC3 in nude mice injected subcutaneously with Tet/pTRE-STGC3/CNE2 cells. STGC3 expression was induced by the intraperitoneal injection of doxycycline (Dox). The volume mean of Tet/pTRE-STGC3/CNE2+Dox xenografts was smaller than that of Tet/pTRE/CNE2+Dox xenografts. In addition, Tet/pTRE-STGC3/CNE2+Dox xenografts showed an increase in the percentage of apoptotic cells, a decrease in Bcl-2 protein expression and an increase in Bax protein expression. A proteomic approach was used to assess the protein expression profile associated with STGC3-mediated apoptosis. Western blotting confirmed the differential up-regulation of prohibitin seen in proteomic analysis. These results indicate that overexpression of STGC3 inhibits xenograft growth in nude mice by enhancing apoptotic cell death through altered expression of apoptosis-related proteins such as Bcl-2, Bax and prohibitin. These data contribute to our understanding of the function of STGC3 in human nasopharyngeal carcinoma and provide new clues for investigating other STGC3-associated tumors
Ultrathin self-assembled anionic polymer membranes for superfast size-selective separation
National Nature Science Foundation of China [21076170, 21376194, 21306155]; research fund for the Doctoral Program of Higher Education [20120121120013]; Fundamental Research Funds for the Central Universities [2012121029]Nanoporous membranes with superior separation performance have become more crucial with increasing concerns in functional nanomaterials. Here novel ultrahigh permeable nanoporous membranes have been fabricated on macroporous supports by self-assembly of anionic polymer on copper hydroxide nanostrand templates in organic solution. This facile approach has a great potential for the fabrication of ultrathin anionic polymer membranes as a general method. The as-fabricated self-assembled membranes have a mean pore size of 5-12 nm and an adjustable thickness as low as 85 nm. They allow superfast permeation of water, and exhibit excellent size-selective separation properties and good fouling resistance for negatively-charged solutes during filtration. The 85 nm thick membrane has an ultrahigh water flux (3306 l m(-2) h(-1) bar(-1)) that is an order of magnitude larger than commercial membranes, and can highly efficiently separate 5 and 15 nm gold nanoparticles from their mixtures. The newly developed nanoporous membranes have a wide application in separation and purification of biomacromolecules and nanoparticles
Orientation Effects in Ballistic High-Strained P-type Si Nanowire FETs
In order to design and optimize high-sensitivity silicon nanowire-field-effect transistor (SiNW FET) pressure sensors, this paper investigates the effects of channel orientations and the uniaxial stress on the ballistic hole transport properties of a strongly quantized SiNW FET placed near the high stress regions of the pressure sensors. A discrete stress-dependent six-band k.p method is used for subband structure calculation, coupled to a two-dimensional Poisson solver for electrostatics. A semi-classical ballistic FET model is then used to evaluate the ballistic current-voltage characteristics of SiNW FETs with and without strain. Our results presented here indicate that [110] is the optimum orientation for the p-type SiNW FETs and sensors. For the ultra-scaled 2.2 nm square SiNW, due to the limit of strong quantum confinement, the effect of the uniaxial stress on the magnitude of ballistic drive current is too small to be considered, except for the [100] orientation. However, for larger 5 nm square SiNW transistors with various transport orientations, the uniaxial tensile stress obviously alters the ballistic performance, while the uniaxial compressive stress slightly changes the ballistic hole current. Furthermore, the competition of injection velocity and carrier density related to the effective hole masses is found to play a critical role in determining the performance of the nanotransistors
Exogenous Melatonin Alleviates Oxidative Damages and Protects Photosystem II in Maize Seedlings Under Drought Stress
The protective role of melatonin in plants against various abiotic stresses have been widely demonstrated, but poorly explored in organ-specific responses and the transmission of melatonin signals across organs. In this study, the effects of melatonin with the root-irrigation method and the leaf-spraying method on the antioxidant system and photosynthetic machinery in maize seedlings under drought stress were investigated. The results showed that drought stress led to the rise in reactive oxygen species (ROS), severe cell death, and degradation of D1 protein, which were mitigated by the melatonin application. The application of melatonin improved the photosynthetic activities and alleviated the oxidative damages of maize seedlings under the drought stress. Compared with the leaf-spraying method, the root-irrigation method was more effective on enhancing drought tolerance. Moreover, maize seedlings made organ-specific physiological responses to the drought stress, and the physiological effects of melatonin varied with the dosage, application methods and plant organs. The signals of exogenous melatonin received by roots could affect the stress responses of leaves, and the melatonin signals perceived by leaves also led to changes in physiological metabolisms in roots under the stress. Consequently, the whole seedlings coordinated the different parts and made a systemic acclimation against the drought stress. Melatonin as a protective agent against abiotic stresses has a potential application prospect in the agricultural industry
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