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1.
Artigo em Zh | MEDLINE | ID: mdl-32062891

RESUMO

Objective: To detect the prevalence of sleep disorders among metro staff and to analyze influencing effects of effort reward imbalance (ERI) on it. Methods: In January 2015, subway driver, dispatcher and station operator from Guangzhou subway were selected as the research object in the whole group sampling method. A total of 1200 questionnaires were distributed and 1124 were valid questionnaires, and the effective questionnaire recovery rate was 93.7%. Based on the effort reward imbalance questionnaire and the self-administered sleep questionnaire, the data of the general demographic characteristics, life satisfaction, occupational stress and sleep status of the respondents were collected. Epi.data3.1 and spss19.0 were used for analyzing. Results: A total of 1124 subway employees were surveyed, with an average age of (28±5) years; the working age was (4.5±3.6) years. ERI occupied 24.7% (278/1124) of the study population and sleep disorders as 42.2% (474/1124) . Single factor analysis showed that marital status, educational level, work position, life satisfaction and ERI could significantly influence sleep disorders of metro staff (P<0.05) . Logistic regression showed that higher effort (adjusted OR=2.56, 95%CI: 1.79-3.68) , lower reward (adjusted OR=1.90, 95%CI: 1.34-2.68) and ERI (adjusted OR=2.33, 95%CI: 1.69-3.22) could increase the risk of sleep disorders after the confounding factors were controlled. ERI (adjusted OR=2.89, 95% CI: 1.80-4.64) , and over commitment (adjusted OR=4.64, 95%CI: 2.81-7.68) could influence the risk of sleep disorders independently when over commitment was evaluated as a moderating variable. Conclusion: Occupational stress as ERI could influence the risk of sleep disorders among metro staff. The situation should not be neglected for occupational health of metro staff.


Assuntos
Saúde Ocupacional , Estresse Ocupacional , Recompensa , Transtornos do Sono-Vigília/epidemiologia , Adulto , China , Estudos Transversais , Humanos , Satisfação no Emprego , Inquéritos e Questionários , Adulto Jovem
2.
Phys Rev Lett ; 122(1): 016802, 2019 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-31012670

RESUMO

The surface of diamond is reported to undergo nonablative photochemical etching when exposed to ultraviolet (UV) radiation which allows controlled single and partial layer removal of lattice layers. Oxygen termination of surface dangling bonds is known to be crucial for the etching process; however, the exact mechanism of carbon ejection remains unclear. We investigate the interaction of UV laser pulses with oxygen-terminated diamond surfaces using atomic-scale surface characterization combined with first-principles time-dependent density functional theory calculations. We present evidence for laser-induced desorption (LID) from carbonyl functional groups at the diamond {001} surface. The doubly bonded carbonyl group is photoexcited into a triply bonded CO-like state, including scission of the underlying C─C bonds. The carbon removal process in LID is atom by atom; therefore, this mechanism provides a novel "top-down" approach for creating nanostructures on the surface of diamond and other carbon-containing semiconductors.

3.
Beijing Da Xue Xue Bao Yi Xue Ban ; 50(1): 85-90, 2018 Feb 18.
Artigo em Zh | MEDLINE | ID: mdl-29483728

RESUMO

OBJECTIVE: Three kinds of zirconia specimens were made respectively by milling of the prisintered blocks and by three dimensional (3D) gel deposition for in vitro evaluation of their optical translucency under three different thicknesses and their color masking effect on discolored teeth. The study aims for establishing the principle for guiding the materials selection in clinical practice. METHODS: Ninety A2-colored zirconia disc specimens with diameter of 14 mm were prepared and were divided into three groups (n=30). (1) Group CZ, by milling of the presintered blanks; (2) Group NZW, by 3D gel deposition, without a color masking opaque inner layer; (3) Group NZY, by 3D gel deposition, with a color masking opaque inner layer. Furthermore, each group was divided into three sub-groups (n=10) according to the sample thickness, i.e., 0.6, 1.0 and 1.5 mm, respectively. The maxillary anterior teeth with severe discoloration, extracted owing to periodontal disease, were collected and embedded. By gentle gridding and polishing a plane, larger than 6 mm2×6 mm2, was generated on the labial surface of each tooth. Chromatic values(CIE1976-L*a*b*) of the zirconia samples in the nine sub-groups were measured by the spectrophotometer Crystaleye in front of the black or white background in a cassette, and the translucency parameter (TP) values were calculated for each sample. Thereafter the zirconia specimens were bonded onto the labial surface of the polished teeth for measuring the chromatic values, using the chromatic value of the medium 1/3 of the standardized Vita A2 as a control. The color aberration ΔE between each zirconia specimen and the control value was calculated, respectively. The results were statistically analyzed by One-way ANOVA and Bonferroni. RESULTS: (1) The optical transparency of the three kinds of zirconia disc specimens with the thickness of 0.6, 1.0 and 1.5 mm was 14.09, 12.31 and 10.45 for group CZ; 19.84, 16.54 and 12.44 for group NZW;14.81, 13.16 and 11.92 for group NZY. In each group, the degree of optical transparency of the specimens showed a clear tendency as in the sub-group 0.6 mm >1.0 mm >1.5 mm. The TP value of the specimens in the three groups with the same thickness showed a tendency of the group NZW >group NZY >group CZ. (2) After bonding onto the polished labial surface of the teeth, the color aberration ΔE of the specimens with the thickness of 0.6, 1.0 and 1.5 mm was calculated to be 10.77, 9.94 and 8.50 for group CZ; 6.84, 5.89 and 5.29 for group NZW; 4.16, 3.92 and 3.67 for group NZY. In each group, the color aberration of the specimens showed a clear tendency as in the sub-group 0.6 mm >1.0 mm >1.5 mm; the color aberration of the three groups with the same thickness was in the order of the group CZ >group NZW >group NZY. CONCLUSION: In all the specimen groups with a fixed specimen thickness, the optical translucency of the specimen was the highest in group NZW made by 3D gel deposition, and the best color masking effect was obtained in specimens with a color masking opaque inner layer in group NZY, where a thickness of 0.6 mm was sufficient enough for obtaining the ideal color masking effect.


Assuntos
Cerâmica , Descoloração de Dente , Zircônio , Cor , Humanos , Teste de Materiais
4.
Phys Chem Chem Phys ; 19(18): 11485-11491, 2017 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-28425542

RESUMO

Perovskite zirconates such as SrZrO3 exhibit improved proton solubility and conductivity when doped with trivalent cations substituting at the Zr site. In this work, we present a detailed study of Sc and Y dopants in SrZrO3 based on first-principles, hybrid density-functional calculations. When substituting at the Zr site (ScZr, YZr), both dopants give rise to a single, deep acceptor level, where the neutral impurity forms a localized hole polaron state. The ε(0/-) charge transition levels are 0.60 eV and 0.58 eV above the valence-band maximum for ScZr and YZr, respectively. Under certain growth conditions, Sc and Y will form self-compensating donor species by substituting at the Sr site (ScSr, YSr), and this is detrimental to proton conductivity. Due to its larger ionic radius, Y exhibits a greater tendency than Sc to self-compensate at the Sr site. We also investigated the proton-dopant association. The binding energy of a proton to a negatively charged acceptor impurity is 0.41 eV for Sc and 0.31 eV for Y, indicating that proton transport is limited by trapping at impurity sites.

5.
J Phys Chem A ; 121(47): 9058-9063, 2017 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-29111726

RESUMO

The potential of C60 as a nucleic acid base (NAB) optical sensor is theoretically explored. We investigate the adsorption of four NABs, namely, adenine, cytosine, guanine, and thymine, on C60 in the gas phase. For the optimal NAB@C60 adsorption configurations, obtained using a dispersion-corrected density functional, we calculate the vis-near-ultraviolet optical response using time-dependent density functional theory. While the isolated C60 and NAB molecules do not exhibit visible optical excitation, we find that C60/NAB conjugation gives rise to distinct spectral features in the visible range. These results suggest that C60 conjugation can be applied for photodetection of individual NABs.

6.
Phys Rev Lett ; 117(22): 227202, 2016 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-27925730

RESUMO

Here we present a study of magnetism in Co_{0.05}Ti_{0.95}O_{2-δ} anatase films grown by pulsed laser deposition under a variety of oxygen partial pressures and deposition rates. Energy-dispersive spectrometry and transmission electron microscopy analyses indicate that a high deposition rate leads to a homogeneous microstructure, while a very low rate or postannealing results in cobalt clustering. Depth resolved low-energy muon spin rotation experiments show that films grown at a low oxygen partial pressure (≈10^{-6} torr) with a uniform structure are fully magnetic, indicating intrinsic ferromagnetism. First principles calculations identify the beneficial role of low oxygen partial pressure in the realization of uniform carrier-mediated ferromagnetism. This work demonstrates that Co:TiO_{2} is an intrinsic diluted magnetic semiconductor.

7.
Phys Chem Chem Phys ; 18(31): 21315-21, 2016 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-27426253

RESUMO

Based on density-functional theory and non-equilibrium Green's function calculations, we demonstrate that endohedral metallofullerenes (EMFs) are reactive to open-shell gases, and therefore have the potential application as selective open-shell gas sensors. The adsorption of eight gas species (CO, H2O, H2S, NO2, NO, SO2, O2 and NH3) on three EMFs (M@C60, M = Ca, Na and Sr) shows that the adsorption energies of the EMFs towards NO2 and NO are significantly higher than the closed-shell species. Moreover, the high selectivity appears relatively insensitive to the inserted metal atoms. The calculated current-voltage characteristics of gold-M@C60-gold structures (M = Ca, Na) show that the adsorption of NO2 leads to significant change in conductivity, suggesting a potential application as an EMF gas resistive sensing device.

8.
Phys Chem Chem Phys ; 18(24): 16224-8, 2016 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-27252042

RESUMO

Through first-principles calculations using the nonequilibrium Green's function formalism together with density functional theory, we study the conductance of double-vacancy zigzag graphene nanoribbons doped with four transition metal atoms Ti, V, Cr and Fe. We show that Ti doping induces large spin-filtering with an efficiency in excess of 90% for bias voltages below 0.5 V, while the other metal adatoms do not induce large spin filtering. This is despite the fact that the Ti dopant possesses small spin moment, while large moments reside on V, Cr and Fe dopants. Our analysis shows that the suppression of transmission in the spin-down channel in the Ti-doped graphene nanoribbon, thus the large spin filtering efficiency, is due to transmission anti-resonance arising from destructive quantum interference. These findings suggest that the decoration of graphene with titanium, and possibly other transition metals, can act as effective spin filters for nanospintronic applications.

9.
J Chem Phys ; 144(2): 021101, 2016 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-26772547

RESUMO

Based on the nonequilibrium Green's function formalism and density-functional theory, we investigate the onset of electrical rectification in a single C59N molecule in conjunction with gold electrodes. Our calculations reveal that rectification is dependent upon the anchoring of the Au atom on C59N; when the Au electrode is singly bonded to a C atom (labeled here as A), the system does not exhibit rectification, whereas when the electrode is connected to the C-C bridge site between two hexagonal rings (labeled here as B), transmission asymmetry is observed, where the rectification ratio reaches up to 2.62 at ±1 V depending on the N doping site relative to the anchoring site. Our analysis of the transmission mechanism shows that N doping of the B configuration causes rectification because more transmission channels are available for transmission in the B configuration than in the A configuration.

10.
Zhonghua Nei Ke Za Zhi ; 55(11): 872-874, 2016 Nov 01.
Artigo em Zh | MEDLINE | ID: mdl-27801344

RESUMO

The expression of CD107a, NKG2D on the surface of natural killer (NK) cells and serum soluble major histocompatibility complex class Ⅰ chain-related A (sMICA) level in patients with extranodal NK/T cell lymphoma, nasal type (ENKL) were detected.We found that CD107a expression was reduced on the surface of NK cells, suggesting impaired NK cell activity in ENKL patients, which may result from decreased NKG2D expression.


Assuntos
Antígenos de Histocompatibilidade Classe I/sangue , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Linfoma Extranodal de Células T-NK/imunologia , Subfamília K de Receptores Semelhantes a Lectina de Células NK/metabolismo , Neoplasias Nasais/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Humanos , Linfoma Extranodal de Células T-NK/sangue , Linfoma Extranodal de Células T-NK/patologia , Neoplasias Nasais/sangue , Neoplasias Nasais/patologia
11.
Phys Rev Lett ; 114(24): 247601, 2015 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-26197012

RESUMO

A first-principles investigation into the magnetic ferroelectric PbTi(1-x)Co(x)O(3) has revealed a bi-stable magnetic system with strong spin-lattice coupling. The local distortions induced by the low-spin to high-spin crossover are ferroelectric in nature, and are characterized by the displacement of the dopant ion with respect to the surrounding O(6) octahedral cage. We demonstrate how this spin-lattice effect could mediate magnetoelectric coupling and possible electric field induced spin-crossover, indicating a promising route to voltage manipulation of isolated spins in a solid-state system.

12.
Phys Chem Chem Phys ; 17(10): 6925-32, 2015 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-25679359

RESUMO

Atom implantation in graphene or graphene nanoribbons offers a rich opportunity to tune the material structure and functional properties. In this study, zigzag graphene nanoribbons with Ti or Sn adatoms stabilised on a double carbon vacancy site are theoretically studied to investigate their sensitivity to sulfur-containing gases (H2S and SO2). Due to the abundance of oxygen in the atmosphere, we also consider the sensitivity of the structures in the presence of oxygen. Density functional theory calculations are performed to determine the adsorption geometry and energetics, and nonequilibrium Green's function method is employed to compute the current-voltage characteristics of the considered systems. Our results demonstrate the sensitivity of both Ti- and Sn-doped systems to H2S, and the mild sensitivity of Ti-doped sensor systems to SO2. The Ti-doped sensor structure exhibits sensitivity to H2S with or without oxidation, while oxidation of the Sn-doped sensor structure reduces its ability to adsorb H2S and SO2 molecules. Interestingly, oxygen dissociates on the Ti-doped sensor structure, but it does not affect the sensor's response to the H2S gas species. Oxidation prevents the dissociation of the H-S bond when H2S adsorbs on the Ti-doped structure, thus enhancing its reusability for this gas species. Our study suggests the potential of Ti- and Sn-doped graphene in selective gas sensing, irrespective of the sensing performance of the bulk oxides.

13.
Genet Mol Res ; 14(3): 7395-405, 2015 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-26214418

RESUMO

The regulatory region of the ribulose-1,5-bisphosphate carboxylase small subunit gene SRS4 from soybean (Glycine max) was cloned using TAIL-PCR and general PCR, and named the rbcS promoter. The promoter was fused with the GUS gene and introduced into Nicotiana tabacum via Agrobacterium-mediated leaf disk transformation. In 4-week-old transgenic tobacco plants, the highest GUS expression levels were observed in the leaves, GUS activity was 7.13- and 7.40-fold higher in leaves than in stems and roots, respectively. Moreover, GUS activity was stimulated by light. In conclusion, spatial and light regulation of the soybean rbcS promoter was observed in N. tabacum, thus illustrating a leaf-specific and light-induced promoter.


Assuntos
Glycine max/genética , Nicotiana/genética , Ribulose-Bifosfato Carboxilase/genética , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , Regulação da Expressão Gênica de Plantas , Luz , Dados de Sequência Molecular , Folhas de Planta/genética , Plantas Geneticamente Modificadas/genética , Reação em Cadeia da Polimerase/métodos , Regiões Promotoras Genéticas , Glycine max/enzimologia , Nicotiana/enzimologia
14.
Phys Rev Lett ; 113(18): 186401, 2014 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-25396383

RESUMO

Based on first-principles density functional calculations we propose a novel Al vacancy induced ferromagnetism occurring at the LaAlO(3) surface of SrTiO(3)/LaAlO(3) bilayers. Magnetism at cation vacancies away from the surface is quenched due to charge compensation. Magnetic surface Al vacancies are stabilized due to the built-in electric field inside the LaAlO(3) region that raises the energy of the defect level, making charge compensation unfavorable. Surface Al vacancies prefer to form clusters and exhibit two-dimensional ferromagnetic alignment mediated by a long-range magnetic interaction. These results are discussed in light of recent experimental observations.

15.
Plant Dis ; 98(11): 1590, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30699833

RESUMO

Bean common mosaic virus (BCMV) is a member of the genus Potyvirus and one of the numerous viruses that can infect Phaseolus vulgaris. In May of 2013, we planted more than 100 varieties of mungbean in fields and a greenhouse of Nanjing. Mungbean (Vigna radiata (Linn.) Wilczek.) with leaves displaying mosaic and shrinkage typical of viral infection was observed in a greenhouse and a field in Nanjing. About 60% of the varieties can be infected. The symptoms in some sources from Southeast Asian countries and wild germplasm are heavier, while the symptoms are lighter on the local varieties. It can be transmitted to mungbean via aphid or mechanical inoculation, or by seeds. The infected leaves were collected for electron micrograph analysis. Pinwheel inclusion and filamentous virus particles were observed, indicating a Potyvirus infection. To confirm the presence of Potyvirus infection, total RNA was extracted from plants from the greenhouse and field, and RT-PCR was performed using universal Potyvirus primers (Sprimer (+) 5'-GGXAAYAAYAGYGGXCAZCC-3'; X=A, G, C or T, Y=T or C, Z=A or G); M4T (5'-GTTTTCCCAGTCACGAC(T)-3'), which amplify a region of the 3' fragment of the RNA-dependent RNA polymerase of potyviruses (1). The 596-bp sequence was found to be 95% identical to the BCMV isolate HB (GenBank Accession No. KC478389.1). To confirm the presence of BCMV, three leaf samples were randomly collected and all were determined to be positive when subjected to ELISA using BCMV-specific antibodies. The virus infecting mungbean was identified as BCMV and the strain was named BCMV-JAAS (KJ866945). Using gene-specific primers (BCMV-cp-F: 5'-CAAAAGGACAAGGATTGAGGA, BCMV-cp-R: 3'-ACAACAAACATTGCCGTAGC) for the reported coat protein gene in BCMV, a 1,080-bp gene fragment was amplified from the total RNA of the isolate, and subsequent sequence analysis indicated that an 862-bp region contained the complete cp gene that encodes a 228 amino acid protein. The nucleotide sequences of the cp gene from the isolate shared 96% homology with the reported BCMV-HB. The phylogenetic trees based on the CP gene show that BCMV-JAAS (KJ866945) was most closely related to other Chinese BCMV isolates (KF439722.1 and AJ132145.1) followed by Azuki mosaic virus (AB012663.1) and Peanut stripe virus (U34972.1). These results indicate that the virus associated with the mosaic disease in mungbean is an isolate of BCMV. To our knowledge, this is the first report of BCMV infecting mungbean in China. BCMV affects a wide range of legume crops and can spread rapidly, causing serious harm. The discovery could effectively control BCMV and characterize the prevalent BCMV strains. Research utilizing whole-genome sequencing of the mungbean isolate is continuing and is currently being expanded to characterize the genetic diversity of the virus, assisting in the study of the evolution of the virus. Reference: (1) J. Chen and J. P. Chen. Chin. J. Virol. 18:372, 2002.

16.
J Nanosci Nanotechnol ; 13(2): 1251-5, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23646613

RESUMO

Graphene based quantum dots and antidots are two nanostructures of primary importance for their fundamental physics and technological applications, particularly in the emerging field of graphene-based nanoelectronics and nanospintronics. Herein, based on first principles density functional theory calculations, we report a comparative study on the electronic structure of these two structurally complementary entities, where the bandgap opening, edge magnetism and the role of hydrogenation are investigated. Our results show the diversity of electronic structures of various dots and antidots, whose properties are sensitive to the edge detailed geometry (including size and shape and edge type). Hydrogen passivation plays an essential roal in affecting the related properties, in particular, it leads to larger bandgap values and suppress the edge magnetism. The frontier orbital analysis is employed to rationalize and compare the complicated nature of dots and antidots. Based on the specific geometrical consideration and the total energy competition of the ground antiferromagnetic and the ferromagnetic states, some magnetic structures (the unpassivated 42-atom-antidot and 54-atom-dot) are proposed to be useful as magnetic switches.

17.
Eur Rev Med Pharmacol Sci ; 26(21): 7797-7812, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36394728

RESUMO

OBJECTIVE: Obesity is characterized by excess fat accumulation and closely associated with insulin resistance and type 2 diabetes. We aimed at exploring the potential effect and mechanism of escin for the treatment of obesity using network pharmacology, and to verify the effect of escin on obese mice. MATERIALS AND METHODS: Escin targets were predicted by DrugBank and SwissTarget database. Potential targets for the treatment of obesity were identified based on the DisGeNET database. Comparative analysis was used to investigate the overlapping genes between escin targets and obesity treatment-related targets. Using STRING database and Cytoscape to analyze interactions among overlapping genes, hub genes were identified. Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted in DAVID. High-fat diet (HFD) -induced obese mice were used to observe the anti-obesity effects of escin. The body weight, relevant biochemical markers and HE staining of fat and liver tissues were determined after escin was administered for 18 weeks. RESULTS: We screened 53 overlapping genes for escin and obesity. The mechanism of intervention of escin in treating obesity may involve 10 hub targets (STAT3, MTOR, NR3C1, IKBKB, PTGS2, MMP9, PRKCA, PRKCD, AR, CYP3A4). The screening and enrichment analysis revealed that the treatment of obesity using escin primarily involved 10 GO enriched terms and 13 related pathways. In vivo, escin can reduce the body weight of obese mice induced by HFD and improve lipid metabolism through lowering triglycerides (TG), total cholesterol (TC), and density lipoprotein (LDL) levels and increasing high density lipoprotein (HDL) levels and decreasing leptin level and increasing adiponectin (ADPN) level. Escin can regulate glucose metabolism caused by obesity through decreasing fasting glucose, postprandial blood glucose and regulating the level of insulin. These obese mice induced by HFD displayed the increased insulin resistance that was associated with the increased inflammatory cytokines, including interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1). Escin may antagonize the increase of MCP-1 and partially antagonize the low-grade inflammation caused by obesity. From the morphological changes of fat and liver tissues stained by HE stain, escin could decrease the size of adipocytes and improve liver necrosis and fatty degeneration in obese mice fed by HFD. CONCLUSIONS: The network pharmacology of escin in treating obesity may involve 10 hub targets (STAT3, MTOR, NR3C1, IKBKB, PTGS2, MMP9, PRKCA, PRKCD, AR, CYP3A4), 10 GO enriched terms and 13 related pathways. In vivo, escin can be potentially used to prevent or treat obesity through reducing the weight, improving glucose and lipid metabolism, partially antagonizing the low-grade inflammation, and improved insulin resistance.


Assuntos
Diabetes Mellitus Tipo 2 , Resistência à Insulina , Animais , Camundongos , Ciclo-Oxigenase 2 , Citocromo P-450 CYP3A/uso terapêutico , Diabetes Mellitus Tipo 2/complicações , Dieta Hiperlipídica , Escina/uso terapêutico , Glucose/metabolismo , Quinase I-kappa B , Inflamação/metabolismo , Metaloproteinase 9 da Matriz , Camundongos Obesos , Obesidade , Serina-Treonina Quinases TOR
18.
Phys Rev Lett ; 106(24): 247002, 2011 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-21770591

RESUMO

Local fluctuations in the distribution of dopant atoms are thought to cause the nanoscale electronic disorder or phase separation in pnictide superconductors. Atom probe tomography has enabled the first direct observations of dopant species clustering in a K-doped 122-phase pnictide. First-principles calculations suggest the coexistence of static magnetism and superconductivity on a lattice parameter length scale over a wide range of dopant concentrations. Our results provide evidence for a mixed scenario of phase coexistence and phase separation, depending on local dopant atom distributions.

19.
Phys Chem Chem Phys ; 13(48): 21243-7, 2011 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-22025089

RESUMO

The electrical and magnetic properties of Zn-doped Fe(3)O(4) at different doping concentrations of Zn have been investigated using a density functional method with generalized-gradient approximation corrected for on-site Coulombic interactions. The electronic structure calculation predicts that Zn(x)Fe(3-x)O(4) (0 ≤x≤ 0.875) is half-metallic with a full spin polarization. The hopping carrier concentration of Zn(x)Fe(3-x)O(4) decreases with increasing x, which indicates a distinct increase in the resistivity. The saturation magnetization of Zn(x)Fe(3-x)O(4) increases evidently with increasing x from x = 0 to x = 0.75 (i.e. from 4.0 to 8.3 µ(B)/f.u.) and then decreases rapidly to zero at x = 1. The robust half-metallicity, large tunability of electrical and magnetic properties of a Zn doped Fe(3)O(4) system make it a promising functional material for spintronic applications.

20.
J Clin Pharm Ther ; 36(5): 614-24, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21916909

RESUMO

WHAT IS KNOWN AND OBJECTIVE: Tacrolimus (TAC) is metabolized mainly by the CYP3A subfamily and extruded into the intestine by P-glycoprotein, which is encoded by the ABCB1 gene. Several studies have suggested that the CYP3A5*3 genotype influenced the pharmacokinetics (PK) of TAC. The CYP3A4*18B and CYP3A5*3 alleles are clinically important in Chinese subjects because of their relatively high frequency. The present study aimed at evaluating the effects of ABCB1 (C1236T-G2677T/A-C3435T), CYP3A4*18B and CYP3A5*3 genetic polymorphisms on TAC PK in healthy Chinese subjects. METHODS: Data were obtained from a comparative bioavailability study of oral TAC formulations (n = 22). TAC whole blood concentrations were measured by LC-MS/MS. Genetic polymorphisms were determined using a direct sequencing method. Nonlinear mixed-effects modelling (NONMEM) was performed to assess the effect of genotypes and demographics on TAC PKs. RESULTS AND DISCUSSION: Both CYP3A4*18B and CYP3A5*3 polymorphisms affected the TAC PK, whereas ABCB1 genetic polymorphisms and other demographic characteristics did not. The combined genotypes of CYP3A4*18B and CYP3A5*3 had a greater impact than either genotype alone, and they were estimated to account for 28·4% of the inter-subject variability of apparent clearance (CL/F) by NONMEM. The CL/F in subjects with CYP3A4*1/*1-CYP3A5*3/*3 was 10·3 L/h and was 48·5% in those not carrying CYP3A4*1/*1-CYP3A5*3/*3. WHAT IS NEW AND CONCLUSION: This is the first study to extensively explore the influence of CYP3A4*18B, CYP3A5*3 and ABCB1 genetic polymorphisms on TAC PK in healthy Chinese subjects. The results demonstrated that subjects with a combined genotype of CYP3A4*1/*1-CYP3A5*3/*3 may require lower TAC doses to achieve target concentration levels and further investigation is needed in larger populations to confirm the clinical benefits.


Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Citocromo P-450 CYP3A/genética , Genética Populacional/métodos , Imunossupressores/farmacocinética , Transplante de Rim , Tacrolimo/farmacocinética , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Adulto , Povo Asiático/genética , Estudos Cross-Over , Citocromo P-450 CYP3A/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Demografia , Feminino , Frequência do Gene , Genética Populacional/estatística & dados numéricos , Humanos , Imunossupressores/sangue , Imunossupressores/farmacologia , Rim/fisiopatologia , Masculino , Modelos Biológicos , Polimorfismo Genético , Polimorfismo de Nucleotídeo Único , Distribuição Aleatória , Reprodutibilidade dos Testes , Tacrolimo/sangue , Tacrolimo/farmacologia , Adulto Jovem
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