1,321 research outputs found
The suppression of Curie temperature by Sr doping in diluted ferromagnetic semiconductor (La1-xSrx)(Zn1-yMny)AsO
(La1-xSrx)(Zn1-yMny)AsO is a two dimensional diluted ferromagnetic
semiconductor that has the advantage of decoupled charge and spin doping. The
substitution of Sr2+ for La3+ and Mn2+ for Zn2+ into the parent semiconductor
LaZnAsO introduces hole carriers and spins, respectively. This advantage
enables us to investigate the influence of carrier doping on the ferromagnetic
ordered state through the control of Sr concentrations in
(La1-xSrx)(Zn0.9Mn0.1)AsO. 10 % Sr doping results in a ferromagnetic ordering
below TC ~ 30 K. Increasing Sr concentration up to 30 % heavily suppresses the
Curie temperature and saturation moments. Neutron scattering measurements
indicate that no structural transition occurs for (La0.9Sr0.1)(Zn0.9Mn0.1)AsO
below 300 K.Comment: Submitted to EP
A multilayered approach of Si/SiO to promote carrier transport in electroluminescence of Si nanocrystals
The electroluminescence (EL) and photoluminescence of Si nanocrystals (Si-nc) from multilayered samples of Si/SiO are investigated. Si-nc are formed within Si and SiO layers after furnace annealing. It is found that the presence of Si interlayers creates extra carrier paths for EL emission. A comparative study is further performed on a multilayered Si/SiO sample and a single-layered one with Si and SiO homogeneously mixed. Both samples have the same ratio of Si to O and the same contents of Si and O. The multilayered sample is found to have higher EL intensity, less turn-on voltage, lower resistance, and higher current efficiency than the single-layered one. The results indicate that Si interlayers in Si/SiO may act as carrier channels, which promote carrier transport and enhance the EL emission of Si-nc
Fermi Surface Evolution, Pseudo Gap and Stagger Gauge Field Fluctuation in Underdoped Cuprates
In the context of t-J model we show that in underdoped regime,beside the
usual long wave length gauge field fluctuation, an additional low energy
fluctuation, staggered gauge field fluctuation plays a crucial role in the
evolution of Fermi surface(FS) as well as the line shape of spectral function
for the cuprates. By including the staggered gauge field fluctuation we
calculate the spectral function of the electrons by RPA(random phase
approximation). The line shape of the spectral function near is very
broad in underdoped case and is quite sharp in overdoped case. For the spectral
function near , the quasiparticle peaks are always very sharp
in both underdoped and overdoped case. The temperature dependence of the
spectral function is also discussed in our present calculation. These results
fit well with the recent ARPES experiments. We also calculate the FS crossover
from a small four segment like FS to a large continuous FS. The reason of such
kind of FS crossover is ascribed to the staggered gauge field fluctuation which
is strong in underdoped regime and becomes much weaker in overdoped regime. The
pseudo gap extracted from the ARPES data can be also interpreted by the
calculation.Comment: 4 pages,6 eps figures include
Bevacizumab Combined With Oxaliplatin/Capecitabine in Patient With Refractory and Recurrent Mucinous Adenocarcinoma of the Appendix: A Case Report
Primary appendiceal adenocarcinoma with peritoneal pseudomyxoma (PPM) has a high recurrence rate and refractory to medical interventions such as repetitive debulking surgery and systemic chemotherapy. Genome-based targeted therapy for such cases has not been well-documented. Here we present a 63-years-old women, who was diagnosed with recurrent mucinous adenocarcinoma of the appendix with local invasions and peritoneal carcinomatosis, was refractory to systemic chemotherapy after surgery. We used a regime developed using whole exome sequencing. Somatic mutations in the genes encoding VEGFR2, FGFR1, FGFR2, FGFR3, and KRAS were identified in the patient's tumor tissue. The patient was then treated with bevacizumab plus oxaliplatin. After 4 months of treatment, pelvic CT showed dramatic reduction of pseudomyoma and a decline of CA199 level from 5436.7 to 1121.4 U/ml. Continual treatment with bevacizumab-capecitabine remained effective and the patient's CA199 level further decreased to 401.26 U/ml according to the follow-up examination on Aug 15th, 2018. Results from this study show the evidence of gene mutations involving VEGF signal activation in the recurrence of appendiceal adenocarcinoma. Our results also suggest the association of these mutations with the effectiveness of anti-VEGF treatment using bevacizumab. Therefore, the screening of gene mutations involved in VEGF signaling and targeted therapy with anti-VEGF drugs may provide a new option to manage refractory/recurrent advanced-stage appendiceal adenocarcinoma
Post-treatment neutrophil-lymphocyte ratio independently predicts amputation in critical limb ischemia without operation
OBJECTIVES: Limited information is available concerning the post-treatment neutrophil-lymphocyte ratio in critical limb ischemia patients who receive conservative therapy. Accordingly, this study was designed to evaluate the predictive value of the post-treatment neutrophil-lymphocyte ratio in critical limb ischemia patients without surgery. METHOD: From January 2009 to January 2011, critical limb ischemia patients were admitted to a vascular center. The demographic data, patient histories, comorbidities and risk factors were documented, and the differential cell count was determined at admission and seven days later after conservative therapy. The cutoff value of the post-treatment neutrophil-lymphocyte ratio was determined by an ROC curve. Patients were divided into groups A and B according to the cutoff value. Amputation-free survival was compared between groups. Univariate and multivariate analyses were used to identify independent risk factors. RESULT: A total of 172 patients were identified with a mean age 71.98±10.09 years; among them, 122 were male. A value of 3.8 was identified as the cutoff value of the post-treatment neutrophil-lymphocyte ratio. Groups A (post-treatment neutrophil-lymphocyte ratio ≥3.8) and B (post-treatment neutrophil-lymphocyte rati
Particulate matter pollution over China and the effects of control policies
China is one of the regions with highest PM(2.5)concentration in the world. In this study, we review the spatio-temporal distribution of PM2.5 mass concentration and components in China and the effect of control measures on PM2.5 concentrations. Annual averaged PM2.5 concentrations in Central-Eastern China reached over 100 mu g m(-3), in some regions even over 150 mu g m(-3). In 2013, only 4.1% of the cities attained the annual average standard of 35 mu g m(-3). Aitken mode particles tend to dominate the total particle number concentration. Depending on the location and time of the year, new particle formation (NPF) has been observed to take place between about 10 and 60% of the days. In most locations, NPF was less frequent at high PM mass loadings. The secondary inorganic particles (i.e., sulfate, nitrate and ammonium) ranked the highest fraction among the PM2.5 species, followed by organic matters (OM), crustal species and element carbon (EC), which accounted for 6-50%, 15-51%, 5-41% and 2-12% of PM2.5, respectively. In response to serious particulate matter pollution, China has taken aggressive steps to improve air quality in the last decade. As a result, the national emissions of primary PM2.5, sulfur dioxide (SO2), and nitrogen oxides (NOx) have been decreasing since 2005, 2006, and 2011, respectively. The emission control policies implemented in the last decade could result in noticeable reduction in PM2,(5)concentrations, contributing to the decreasing PM2.5 trends observed in Beijing, Shanghai, and Guangzhou. However, the control policies issued before 2010 are insufficient to improve PM2.5 air quality notably in future. An optimal mix of energy-saving and end-of-pipe control measures should be implemented, more ambitious control policies for NMVOC and NH3 should be enforced, and special control measures in winter should be applied. 40-70% emissions should be cut off to attain PM2.5 standard. (C) 2017 Elsevier B.V.All rights reserved.Peer reviewe
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