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1.
Ann Clin Microbiol Antimicrob ; 16(1): 28, 2017 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-28399856

RESUMO

BACKGROUND: The nasal cavity is the main colonization site of Staphylococcus aureus (S. aureus) in human body. Nasal carriage may be a strong risk factor for some serious infection. There was still limited information about the nasal carriage for S. aureus in south China. METHODS: Sought to determine the prevalence and molecular characteristics of S. aureus nasal carriage, 295 volunteers residing on a medicine campus were investigated and sampled the nasal cavity swab. Selected S. aureus isolates were carried through molecular analysis, including pulsed-field gel electrophoresis (PFGE), multilocus sequence analysis, staphylococcal cassette chromosome mec (SCCmec) and virulence gene detection. RESULTS: A total of 73 S. aureus isolates were recovered from separate subjects (24.7%, 73/295), with one methicillin-resistant S. aureus (MRSA) isolate (0.3%, 1/295). Among the 73 isolates, 71 isolates were successfully grouped into 13 pulsotypes by PFGE analysis, with profiles A and L the most prevalent; 12 sequence types (STs) were found among the 23 isolates which had similar drug resistant spectrum. ST59, ST188 and ST1 were the most prevalent, accounting for 17.4, 13.0 and 13.0% of all isolates, respectively. The MRSA isolate presented ST8-SCCmec III. 56.5% of isolates carried both the staphylococcal enterotoxin A (sea) and enterotoxin B (seb) genes. 83.6% of the S. aureus isolates were resistant to penicillin, all isolates were susceptible to quinupristin/dalfopristin, levofloxacin, teicoplanin and vancomycin. The most common risk factors for S. aureus carriage were being male, age ≤30 years, and nasal cavity cleaning habits. CONCLUSIONS: Colonization by S. aureus was greater among male and young age (20-30 years) students and those with irregularity nasal cleaning. The S. aureus isolates selected were revealed into various sequence types and pulsotypes, indicating molecular heterogeneity among S. aureus isolates from the populations in the medical college in Guangzhou.


Assuntos
Portador Sadio/epidemiologia , Mucosa Nasal/microbiologia , Infecções Estafilocócicas/epidemiologia , Staphylococcus aureus/isolamento & purificação , Adolescente , Adulto , Fatores Etários , Idoso , Comportamento , Criança , China/epidemiologia , Estudos Transversais , Feminino , Variação Genética , Genótipo , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Tipagem Molecular , Prevalência , Fatores de Risco , Fatores Sexuais , Staphylococcus aureus/classificação , Staphylococcus aureus/genética , Universidades , Fatores de Virulência/genética , Adulto Jovem
2.
Zhonghua Nei Ke Za Zhi ; 55(11): 863-868, 2016 Nov 01.
Artigo em Chinês | MEDLINE | ID: mdl-27801342

RESUMO

Objective: To compare the success rates of wire-guided biliary cannulation (WGC) and conventional cannulation (CC) and their effect on the outcome of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP). Methods: All randomized controlled trials (RCTs) were collected by searching CNKI, WanFang Data, CBM, PubMed, Embase and Cochrane Library.The assessment of methodological quality and data extraction of the included studies were performed independently by two reviewers. Meta-analysis was conducted with RevMan 5.2 software. Results: Ten RCTs, with a total of 3 262 patients enrolled, were retrieved.Meta-analysis demonstrated that WGC had a higher success rate(RR=1.04, 95%CI 1.01-1.06, P<0.01)and a lower risk of PEP after cannulation (RR=0.54, 95%CI 0.41-0.71, P<0.01). The main reason for the lower risk of PEP was due to lower proportion of mild PEP patients after WGC(RR=0.52, 95%CI 0.36-0.73, P<0.01), while the incidence of modest and severe PEP was comparable in the two groups(modest group: RR=0.84, 95%CI 0.43-1.64, P=0.61; severe group: RR=0.53, 95%CI 0.22-1.31, P=0.17). Conclusion: WGC may increase the success rate of cannulation and reduce the incidence of PEP because of less complications of mild PEP.


Assuntos
Cateterismo/métodos , Colangiopancreatografia Retrógrada Endoscópica/efeitos adversos , Pancreatite/epidemiologia , Ensaios Clínicos Controlados Aleatórios como Assunto , Cateterismo/efeitos adversos , Cateterismo/instrumentação , Humanos , Incidência , Pancreatite/etiologia , Complicações Pós-Operatórias/epidemiologia , Resultado do Tratamento
3.
J Nanosci Nanotechnol ; 11(3): 2696-9, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21449457

RESUMO

Magnetic properties and growth mechanism of ultrathin Co films on Si(111)-7 x 7 surface have been studied by using both surface magneto-optic Kerr effect (SMOKE) and scanning tunneling microscopy (STM), respectively. STM results show that the growth mechanism of ultrathin Co films on Si(111)-7 x 7 surface at room temperature belongs to Stranski-Krastanov (SK) growth mode. Due to formation of CoSi2 layer, no magnetic signal could be detected by SMOKE for 1-4 ML Co deposited on Si(111) surface. Because of rougher surface, both longitudinal and perpendicular magnetic anisotropy configuration appear for 4.2-10 ML Co/Si(111) films. When the Co thickness is increased to 10 ML, only longitudinal anisotropy configuration is found, resulting from the contribution to the volume anisotropy. Furthermore, in-plane coercivity increases with Co coverage because of enhancement of ferromagnetic coupling with Co thickness, out-of-plane coercivity increases with Co coverage due to the increment of demagnetized field, induced by the rougher Co surface and pinhole structures.


Assuntos
Cobalto/química , Cristalização/métodos , Magnetismo , Membranas Artificiais , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Silício/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
4.
J Nanosci Nanotechnol ; 11(12): 11133-7, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22409071

RESUMO

The microstructure and magnetic properties of multilayer [Os(t)/FePt(x)]n films on a glass substrate with a 10 nm Os buffer layer by ion beam sputtering have been studied as a function of the annealing temperatures between 300 and 800 degrees C. Here, t = 0.2, 1 or 5 nm and x varied from 10, 20, 25, 50, to 100 nm with its associated n value of 10, 5, 4, 2, and 1, respectively. No diffusion evidence was found in samples with a thin Os layer and t > or = 1 nm. The average grain size of the multilayer films can be well controlled by both annealing temperature and thickness of the FePt layer by a very thin Os space layer with t > or = 1 nm. The enhancement of H(c) can be understood from the fact that for a FePt film with an Os spacer layers, the increasing number of Os layer will inhibit the grain growth of FePt grains and enriches the grain boundary. We have experimentally demonstrated that even with a very thin 1 nm Os spacer layers, the [Os(t)/FePt(x)]n multilayer films can exhibit good hard magnetic properties and are attractive candidates for ultrahigh density magnetic recording media.

5.
J Nanosci Nanotechnol ; 10(7): 4581-5, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21128460

RESUMO

Periodic Ag line arrays with different line pitches from 500 nm to 950 nm on ITO coated glass substrates have been fabricated by using electron-beam lithography (EBL) technique for studying the color light guide in a display system. The patterned Ag line array is used as a light outcoupling and color-selection component due to the emission wavelength changed by the Ag line arrays with different periodic distances that could achieve color variation. We have demonstrated that the ITO coated glass substrates containing periodic Ag line arrays with varied line pitches can be used as a color filter in a display device. This means that with a proper metallic nanostructure layer, the red, green, and blue colors in a display system can be obtained without a traditional color filter for modern multi-applications of optoelectronic display devices.

6.
J Nanosci Nanotechnol ; 10(7): 4663-6, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21128475

RESUMO

Co nanoislands on the Au(111) and Cu(111) surfaces have been studied by scanning tunneling microscopy and spectroscopy. The experimental results showed that Co nanoislands prefer to aggregate at the step edge and dislocation sites on the reconstructed Au(111) surface and at the step edge on the Cu(111) surface, respectively. In addition, based on dZ/dV-V spectra, in both the Co/Au(111) and the Co/Cu(111) systems, Gundlach oscillation was observed. From the peak shift of dZ/dV-V spectra between Co nanoisland and substrate surface, we can quantitatively obtain that the constant energy separation is -0.13 +/- 0.01 eV for the Co/Au(111) system, and 0.41 +/- 0.02 eV for the Co/Cu(111) system, respectively. These values indicate the work function difference between Co nanoisland and these surfaces.

7.
Phys Rev Lett ; 98(15): 157206, 2007 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-17501380

RESUMO

The evolution of the Kondo effect and antiferromagnetic (AF) correlations with size reduction in CePt2 nanoparticles (3.1-26 nm) is studied by analysis of the temperature-dependent specific heat and magnetic susceptibility. The AF correlations diminish with size reduction. The Kondo effect predominates at small particle size with trivalent, small Kondo temperature (TK) magnetic regions coexisting with strongly mixed-valent, large TK nonmagnetic regions. We discuss the role of structural disorder, background density of states and the electronic quantum size effect on the results.

8.
Phys Rev Lett ; 99(21): 216103, 2007 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-18233232

RESUMO

Gundlach oscillation (or the standing-wave state) is a general phenomenon manifesting in the tunneling spectrum acquired from a metal surface using scanning tunneling spectroscopy. Previous studies relate the energy shift between peaks of the lowest-order Gundlach oscillation observed on the thin film and the metal substrate to the difference in their work functions. By observing Gundlach oscillations on Ag/Au(111), Ag/Cu(111), and Co/Cu(111) systems, we demonstrate that the work function difference is not the energy shift of the lowest order but the ones of higher order where a constant energy shift exhibits. Higher order Gundlach oscillations can thus be applied to determine the work function of thin metal films precisely.

9.
Phys Rev E Stat Nonlin Soft Matter Phys ; 72(3 Pt 1): 031408, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16241436

RESUMO

Magnetite nanoparticles with diameters of 7, 9, and 12 nm have been prepared by a chemical coprecipitation method. The transmission of light through magnetic fluid containing these nanoparticles has been investigated as a function of film thickness with wavelength between 400 and 750 nm, and applied magnetic fields up to 275 Oe. The transmission threshold shifts to the lower wavelength side with decreasing magnetic fluid film thickness as well as the particle size. For a given film thickness, the transmittance increases with increasing magnetic field for films with a particle size of 7 and 9 nm, but decreases in the 12-nm film. This is attributed to the competition between the van der Waals and dipole-dipole interaction.

10.
Phys Rev E Stat Nonlin Soft Matter Phys ; 71(6 Pt 2): 067102, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16089915

RESUMO

The motion of a particle in the field of a time-dependent potential is studied here both at absolute zero and in the presence of thermal agitation. The potential executes either random fluctuations or deterministic harmonic oscillations. Assuming absorbing boundaries it is always possible to find an exit time tau(ex)(kappa) which has a local minimum as a function of the potential flip rate kappa. Thus resonant activation, usually associated with diffussive systems, exists in purely deterministic systems as well. Thermal agitation merely extends the range of admissible initial conditions and renders all exit times finite.

11.
Phys Rev E Stat Nonlin Soft Matter Phys ; 64(1 Pt 1): 012101, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11461302

RESUMO

A thermally relaxing system with a harmonically oscillating barrier height is considered. The dynamics of the system are described by a Smoluchowski equation with a time dependent right hand side. For both absorbing and reflecting boundary conditions, the solutions of this equation show that the oscillating system has the same resonant properties, and the same dependence on initial conditions, respectively, on the phase of the harmonic oscillations, as a conventional resonant system in which the barrier executes dichotomic Markovian fluctuations.


Assuntos
Biofísica/métodos , Algoritmos , Cadeias de Markov , Modelos Estatísticos , Oscilometria , Temperatura , Fatores de Tempo
12.
Hear Res ; 137(1-2): 174-7, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10545645

RESUMO

Single cortical auditory neurons sequentially isolated within orthogonal electrode penetrations in the mouse were studied using tonal stimulation. They had common functional properties, such as firing pattern, best frequency, minimum threshold, sharpness of frequency tuning and onset latency. The finding suggests that there is columnar organization in the cortex.


Assuntos
Córtex Auditivo/anatomia & histologia , Córtex Auditivo/fisiologia , Animais , Limiar Auditivo , Potenciais Evocados Auditivos , Camundongos , Microeletrodos , Neurônios/citologia , Neurônios/fisiologia
13.
Neuroscience ; 92(2): 577-82, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10408606

RESUMO

In this study, the mechanism of transferrin-free iron uptake by brain neuronal cells was investigated using the cultured cerebellar granule cells. Effects of incubation time, iron concentration, temperature and other divalent metals on the cellular uptake were determined. After five days of plating, the cells were incubated with different concentrations of transferrin-free iron in isotonic sucrose solution at different temperatures for a certain time. The cellular transferrin-free iron uptake was analysed by measuring the cellular radioactivity with a gamma-counter. The result showed that the cultured cerebellar granule cells had the capacity to acquire transferrin-free iron at pH 6.5, at which it was demonstrated that transferrin binds iron very poorly and only very little transferrin can be internalized by reticulocytes and HeLa cells. The iron uptake by cells increased with incubation time in a linear manner at a rate of 0.1076 pmol/microg protein/min within the first 10 min. The uptake was time- and temperature-dependent, iron concentration saturable, and inhibited by several divalent metal ions, such as Co2+, Zn2+, Mn2+ and Ni2+. These characteristics of transferrin-free iron uptake by the cultured cerebellar granule cells observed in this study, similar to those obtained from cells outside of the brain, implied that a carrier-mediated iron transport system might be present on the membrane of this type of brain neuronal cells. In addition, no significant difference in malondialdehyde measurement was found when the cells were incubated without or with the lower concentrations of iron (< 4 microM) for 20 min at 37 degrees C, demonstrating that this system was valid for studying membrane iron transport in this type of brain neuronal cell.


Assuntos
Proteínas de Transporte/metabolismo , Cerebelo/metabolismo , Compostos Ferrosos/farmacologia , Neurônios/metabolismo , Animais , Células Cultivadas , Metais Pesados/farmacologia , Ratos , Ratos Sprague-Dawley , Transferrina/fisiologia
14.
Artigo em Inglês | MEDLINE | ID: mdl-11969629

RESUMO

The distribution Q(t) of magnetization reversal times in a small uniaxial particle is computed here directly from Brown's Fokker-Planck equation. Constant applied field and axial symmetry are assumed. The Laplace transform of Q(t) has the form Q(z)=F(1)(z)/F(2)(z) where the regular functions F(i)(z) are defined by a solution of a Volterra integral equation. A separate integral equation is derived for the function dF(2)(z)/dz, and the poles and residues of Q(z) may then be found numerically with arbitary precision.

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