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High-power orbital angular momentum (OAM) beams have distinct advantages in improving capacity and data receiving for free-space optical communication systems at long distances. Utilizing the coherent combination of a beam array technique and helical phase approximation by a piston phase array, we have proposed a generating system for a novel high-power beam carrying OAM, which could overcome the power limitations of a common vortex phase modulator and a single beam. The characteristics of this generating method and the orthogonality of the generated OAM beams with different eigenstates have been theoretically analyzed and verified. Also a high-power OAM beam produced by coherent beam combination (CBC) of a six-element hexagonal fiber amplifier array has been experimentally implemented. Results show that the CBC technique utilized to control the piston phase differences among the array beams has a high efficiency of 96.3%. On the premise of CBC, we have obtained novel vortex beams carrying OAM of
by applying an additional piston phase array modulation on the corresponding beam array. The experimental results agree approximately with the theoretical analysis. This work could be beneficial to areas that need high-power OAM beams, such as ultra-long distance free-space optical communications, biomedical treatments, and powerful trapping and manipulation under deep potential wells.
This paper presents new LA-ICP-MS zircon U–Pb chronology, whole-rock geochemical and zircon Hf isotopic data for the felsic lavas of the Huili Group from the southwestern Yangtze Block. LA-ICP-MS zircon U–Pb dating shows that these rocks were emplaced in Late Mesoproterozoic time (∼1028 to 1019 Ma). Relative to typical I-type and S-type granitoids, all the samples are characterized by low Sr and Eu, and high high-field-strength element contents, high TFeO/MgO, enriched rare earth element compositions and negative Eu anomalies, indicating that they share the geochemical signatures of A-type granitoid. They can be further divided into two groups: Group I and Group II. Group I are A1-type felsic rocks and were produced by fractional crystallization of alkaline basaltic magmas. The Group II felsic lavas belong to the A2-type and were derived by partial melting of a crustal source with mixing of mantle-derived magmas. Both Group I and Group II felsic lavas may erupt in a continental back-arc setting. The coexistence of A1- and A2-type rocks in the southwestern Yangtze Block suggests that they can occur in the same tectonic setting.
The description of the gravitational field at the surface of the Earth requires two quantities: the absolute value of the gravitational acceleration and the gravitational direction (deviation from vertical direction). At present, the various gravimeters measure the former quantity, and there is no effective instrument for monitoring the latter. This shortcoming seriously affects the comprehension and further knowledge of the gravitational field.
In traditional antenna design, metal components are not placed in the central part of the antenna as they change the characteristics of near field radiation. However, we show that placing a metal ring in the centre of the strip lines, which connect the ends of folded high-frequency dipoles, does not damage the performance of the feed. Instead it significantly improves the voltage standing wave ratio of the feed whilst other performance indicators are not compromised. Thus, our findings show an excellent way of improving the wide band feed. Based on this foundation, a new circularly polarised feed for operation between 0.4 to 2 GHz is introduced for the Chinese Spectral Radioheliograph in this paper. The issue of a feed impedance matching network is investigated. By optimising the impedance matching, the performance of the feed is enhanced with respect to the previous realisations of the Eleven feed. The simulation and experimental results show that the gain of the feed is about 10 dBi, and the VSWR is less than 2:1. In addition, the feed has a low axial ratio, fixed phase centre location, and constant beam width in the range of 0.4 to 2 GHz.
We aimed to examine the contribution of blood lipids to the association between BMI and blood pressure (BP) in children with overweight and obesity. Data were collected in elementary and high schools of Chaoyang District, Beijing, China in 2012. Participants’ weight, height, BP and fasting plasma lipid profile were measured by standard protocols. Mediation analysis was used to examine the mediation role of blood lipids on the relation between BMI and BP, with age included as a covariate. We found that in boys 8·29 % (mediation effect=0·106, P=0·012) of the association between BMI and systolic BP was mediated through TAG. TAG mediated 12·53 % (mediation effect=0·093, P=0·018) and LDL-cholesterol mediated 7·75 % (mediation effect=0·57, P=0·046) of the association between BMI and diastolic BP was mediated by TAG and LDL-cholesterol, respectively. However, blood lipids did not show the mediation effect in girls. Our findings suggested that there was a sex difference in the contribution of blood lipids to the association between BMI and BP. Controlling TAG or LDL-cholesterol may be beneficial for reducing the risk of the BMI-related high BP in overweight boys; however, this outcome is not the case when controlling TAG or LDL-cholesterol in girls. This study may provide clues to explore the underlying mechanism of the association between obesity and hypertension.
The aim of the present study was to investigate the prevalence of hyperhomocysteinaemia (HHCY; total plasma homocysteine (tHcy) concentration >15 μmol/l) and its major determinants in healthy Chinese northerners. A descriptive and cross-sectional study was conducted in Shaanxi Province, China. The study sample included 2645 participants (1042 men and 1603 women) aged >20 years. Demographic characteristics and lifestyle factors were assessed via questionnaire interviews and physical examination. Plasma levels of homocysteine and folate and methylenetetrahydrofolate reductase (MTHFR) gene polymorphism were determined according to standard methods. The prevalence of HHCY was 67·7 % (81·4 % in men and 58·8 % in women). The geometric mean of tHcy concentration was 19·1 μmol/l. The OR of HHCY were 0·44 (95 % CI 0·34, 0·57) for women v. men; 1·95 (95 % CI 1·41, 2·70), 1·41 (95 % CI 1·05, 1·88) and 0·76 (95 % CI 0·64, 0·89) for participants with smoking and alcohol drinking cessation and improved physical activity levels, respectively; 0·25 (95 % CI 0·17, 0·38), 0·33 (95 % CI 0·22, 0·49) and 0·56 (95 % CI 0·36, 0·88) for participants with an education level of elementary school, secondary school and university v. illiterate, respectively; 1·41 (95 % CI 1·13, 1·75) and 3·05 (95 % CI 2·35, 3·97) for participants with CT and TT v. CC genotype at MTHFR 677C → T polymorphism, respectively. These results demonstrate that the prevalence of HHCY is considerably high in Chinese northerners, especially in TT subjects, suggesting that implementation of tHcy-lowering strategies, such as lifestyle changes, is necessary.
The family of interferon-inducible transmembrane proteins (IFITMs) plays a crucial role in inhibiting proliferation, promoting homotypic cell adhesion and mediating germ cell development. In the present study, the full-length cDNAs of zebrafish ifitm1 (744 bp) and ifitm3 (702 bp) were obtained by rapid amplification of cDNA ends (RACE). Reverse transcription polymerase chain reaction (RT-PCR) analysis showed that ifitm1 mRNA was expressed in the ovary, testis, brain, muscle, liver and kidney, while ifitm3 mRNA was only detected in the ovary. Based on in situ hybridization, ifitm1 mRNA was found to be strongly expressed in the ooplasm from stage I to stage II and ifitm3 mRNA was also strongly expressed in the ooplasm from stage I to stage II, furthermore ifitm3 expression ultimately localized to the cortex region beneath the plasma membrane of stage IV oocytes. During development, ifitm1 expression was initially detected in the enveloping layer cells and deep layer cells of shield stage embryos. Then, throughout the segmentation phase (10.25–24 hours post-fertilization (hpf)), ifitm1 expression was mainly detected in the head, trunk and tail regions. Unlike ifitm1, ifitm3 expression was initially detected in sphere stage embryos and was then broadly expressed throughout the embryo from the 70% epiboly stage to 24 hpf. Interestingly, ifitm3 was also expressed in primordial germ cells (PGCs) from the bud stage to 24 hpf. This expression analysis indicates that zebrafish ifitm1 may play a critical role in early organogenesis and may perform immune or hematopoietic functions and ifitm3 might be necessary for PGC migration and the formation of female germ cells.
To evaluate the accuracy of real-time polymerase chain reaction (PCR) for Clostridium difficile–associated disease (CDAD) detection, after hospital CDAD rates significantly increased following real-time PCR initiation for CDAD diagnosis.
Hospital-wide surveillance study following examination of CDAD incidence density rates by interrupted time series design.
Large university-based hospital.
Hospitalized adult patients.
CDAD rates were compared before and after real-time PCR implementation in a university hospital and in the absence of physician and infection control practice changes. After real-time PCR introduction, all hospitalized adult patients were screened for C. difficile by testing a fecal specimen by real-time PCR, toxin enzyme-linked immunosorbent assay, and toxigenic culture.
CDAD hospital rates significantly increased after changing from cell culture cytotoxicity assay to a real-time PCR assay. One hundred ninety-nine hospitalized subjects were enrolled, and 101 fecal specimens were collected. C. difficile was detected in 18 subjects (18%), including 5 subjects (28%) with either definite or probable CDAD and 13 patients (72%) with asymptomatic C. difficile colonization.
The majority of healthcare-associated diarrhea is not attributable to CDAD, and the prevalence of asymptomatic C. difficile colonization exceeds CDAD rates in healthcare facilities. PCR detection of asymptomatic C. difficile colonization among patients with non-CDAD diarrhea may be contributing to rising CDAD rates and a significant number of CDAD false positives. PCR may be useful for CDAD screening, but further study is needed to guide interpretation of PCR detection of C. difficile and the value of confirmatory tests. A gold standard CDAD diagnostic assay is needed.
The three-dimensional instabilities of axisymmetric flow are investigated in a laterally heated vertical cylinder by linear stability analysis. Heating is confined to a central zone on the sidewall of the cylinder, while other parts of the sidewall are insulated and both ends of the cylinder are cooled. The length of the heated zone equals the radius of the cylinder. For three different aspect ratios,
$A= 1.92 $
, 2, 2.1 (
/radius), the dependence of the critical Rayleigh number on the Prandtl number (from 0.02 to 6.7) has been studied in detail. For such a kind of laterally heated convection, some interesting stability results are obtained. A monotonous instability curve is obtained for
$A= 1.92 $
, while the instability curves for
$A= 2 $
$A= 2.1 $
are non-monotonous and multivalued. In particular, an instability island has been found for
. Moreover, mechanisms corresponding to different instability results are obtained when the Prandtl number changes. At small Prandtl number, the flow is oscillatory unstable, which is dominated by hydrodynamic instability. At intermediate Prandtl number, the interaction between buoyancy and shear in the base flow plays a more important role than pure hydrodynamic instability. At even higher Prandtl number, Rayleigh–Bénard instability becomes the dominant process and the flow loses stability through steady bifurcation.
A joint diagnostic system was established for the diagnosis of laser-driven shock wave experiments. The system has high temporal resolution (time resolution ~12 ps) and high spatial resolution (spatial resolution ~7 μm) and fits for diagnostics of the experiment with small sample size and short time physical process. The joint diagnostic system was applied for shock wave measurement on the Shenguang-II laser facility. The passive shock breakout signal and active diagnostic signal were simultaneously obtained. The temporal measurement reliability of the system was verified using a multi-layered target. The experimental results show that the two measurement results were consistent.
Transparent and high preferential c-axis-oriented ZnO thin films doped with SiO2 have been prepared by sol–gel method using zinc nitrate and tetraethylorthosilicate as precursors, absolute ethanol as solvent, and diethanolamine as sol stabilizer. Thin film deposition was performed by spin coating technique at a spinning speed of 2000 rpm/sec on glass substrate followed by calcinations at 500 °C. The structural characteristics of the samples were analyzed by x-ray diffractometer and atomic force microscope. The optical properties were studied by an ultraviolet–visible spectrophotometer. The results show that all the prepared ZnO thin films have a compact hexagonal wurtzite structure. With the change in the amount of SiO2 dopants, the intensity of (002) peak, particle size, surface root mean square roughness, thickness, transmittance, absorbance, and the optical band gap of the ZnO–SiO2 thin films were changed as well.
Observational studies have indicated that soya food consumption is inversely associated with blood pressure (BP). Evidence from randomised controlled trials (RCT) on the BP-lowering effects of soya protein intake is inconclusive. We aimed to evaluate the effectiveness of soya protein intake in lowering BP. The PubMed database was searched for published RCT in the English language through to April 2010, which compared a soya protein diet with a control diet. We conducted a random-effects meta-analysis to examine the effects of soya protein on BP. Subgroup and meta-regression analyses were performed to explore possible explanations for heterogeneity among trials. Meta-analyses of twenty-seven RCT showed a mean decrease of 2·21 mmHg (95 % CI − 4·10, − 0·33; P = 0·021) for systolic BP (SBP) and 1·44 mmHg (95 % CI − 2·56, − 0·31; P = 0·012) for diastolic BP (DBP), comparing the participants in the soya protein group with those in the control group. Soya protein consumption significantly reduced SBP and DBP in both hypertensive and normotensive subjects, and the reductions were markedly greater in hypertensive subjects. Significant and greater BP reductions were also observed in trials using carbohydrate, but not milk products, as the control diet. Meta-regression analyses further revealed a significantly inverse association between pre-treatment BP and the level of BP reductions. In conclusion, soya protein intake, compared with a control diet, significantly reduces both SBP and DBP, but the BP reductions are related to pre-treatment BP levels of subjects and the type of control diet used as comparison.
We report the use of nickel-platinum silicide (NiPtSi) as a source/drain (S/D) material for strain engineering in P-MOSFETs to improve drive current performance. The material and electrical characteristics of NiPtSi with various Pt concentrations was investigated and compared with those of NiSi. Ni0.95Pt0.05Si was selected for device integration. A 0.18 μm gate length P-MOSFET achieved a 22% gain in IDsat when Ni0.95Pt0.05Si S/D is employed instead of NiSi S/D. The enhancement is attributed to strain modification effects related to the nickel-platinum silicidation process.
We investigated the material and electrical characteristics of platinum and ytterbium silicides for potential applications as metallic Schottky-barrier source/drain (S/D) and fully-silicided (FUSI) gate electrodes in fin field-effect transistors (FinFETs). Due to the low electro-negativity parameter of ytterbium, a low temperature silicidation process was developed to avoid the reaction of ytterbium with the isolation regions (i.e. SiO2 and SiN) to integrate ytterbium silicide successfully in mesa-isolated n-FinFETs. The integration of FUSI metal gate into p-FinFETs was also explored in this work and a novel two-step silicidation process that integrates simultaneously two different phases of platinum silicide with the appropriate work function values for gate electrode and source/drain application was demonstrated.
Zr/Ti an Hf/Ti composite nitrate were developed as single-source precursors for deposition of multi-component metal oxide films. X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) analyses confirmed that ZrxTi1-xO2 and HfxTi1-xO2 films were successfully prepared by the CVD technique from these composite precursors. The Zr/Ti nitrate can be taken as a solid solution of the individual Zr and Ti nitrate, and the Zr/Ti molar ratio in as-deposited ZrxTi1-xO2 films is nicely consistent with that of the precursor. The Hf/Ti nitrate appears to be a mixture of the Zr and Ti nitrates and the composition of the as-deposited HfxTi1-xO2 films depends remarkably on the heating time of precursor. Both ZrxTi1-xO2 and HfxTi1-xO2 films exhibit trading-off properties between band gap and dielectric constant, which suggesting that ZrxTi1-xO2 and HfxTi1-xO2 can be the promising candidates for gate dielectric application to improve the scalability and reduce the leakage current of the next generation complementary metal-oxide-semiconductor transistor (CMOS) devices.
We report thin SGOI (Silicon Germanium on Insulator) with 65% Ge concentration p- MOSFET (Metal-Oxide-Semiconductor-Field-Effect-Transistor) using Ni-germanosilicide Schottky S/D (source/drain) and HfO2/TaN gate stack integrated with conventional self-aligned top gate process. Unlike high temperature S/D activation needed for conventional transistor, low Ni-germanosilicide S/D formation temperature contributes to the excellent capacitance-voltage characteristic, low gate leakage current and hence, well-behaved transistor performance. In addition, SOI structure suppresses the junction leakage problem, resulting in good agreement between the source current and drain current of the MOSFET.
In this paper, the material and electrical characteristics of Nickel-Silicon-Carbon (NiSi:C) films were investigated for the first time to ascertain the compatibility of NiSi:C contacts to silicon-carbon (Si:C) source/drain stressors. The incorporation of 1 atomic percent of carbon was found to increase both the Ni2Si-to-NiSi and NiSi-to-NiSi2 transformation temperatures. Our results show that the incorporation of carbon stabilizes the interfacial and surface morphology of NiSi:C films. We speculate that the incorporated carbon segregates into the NiSi:C grain boundaries and suppresses film agglomeration and NiSi-to-NiSi2 phase transformation. X-ray diffraction analysis further revealed that the formed NiSi:C films possessed a preferred orientation. Current-voltage measurements for NiSi and NiSi:C n+/p junctions exhibit similar cumulative distribution for junction leakage indicating that carbon incorporation does not have a detrimental impact on the n+/p junction integrity. Our results suggest that NiSi:C is a suitable self-aligned contact metal silicide to n-channel MOSFETs with SiC S/D stressors in a similar manner to the way in which NiSiGe is used for p-channel MOSFETs with SiGe S/D stressors.