43 research outputs found
Understanding the Role of Coordinatively Unsaturated Al3+ Sites on Nanoshaped Al2O3 for Creating Uniform NiโCu Alloys for Selective Hydrogenation of Acetylene
Acknowledgments This work was financially supported by the National Key R&D Program of China (2021YFB3801600), the National Natural Science Foundation of China (22218017), and the Fundamental Research Funds for the Central Universities (buctrc201921, JD2223). We acknowledge the Beijing Synchrotron Radiation Facility (BSRF) for providing the experimental resources for XAS experiments.Peer reviewedPostprin
Author Correction: Craniometrics Reveal "Two Layers" of Prehistoric Human Dispersal in Eastern Eurasia
Correction to: Scientific Reports https://doi.org/10.1038/s41598-018-35426-z, published online 05 February 201
The next detectors for gravitational wave astronomy
This paper focuses on the next detectors for gravitational wave astronomy
which will be required after the current ground based detectors have completed
their initial observations, and probably achieved the first direct detection of
gravitational waves. The next detectors will need to have greater sensitivity,
while also enabling the world array of detectors to have improved angular
resolution to allow localisation of signal sources. Sect. 1 of this paper
begins by reviewing proposals for the next ground based detectors, and presents
an analysis of the sensitivity of an 8 km armlength detector, which is proposed
as a safe and cost-effective means to attain a 4-fold improvement in
sensitivity. The scientific benefits of creating a pair of such detectors in
China and Australia is emphasised. Sect. 2 of this paper discusses the high
performance suspension systems for test masses that will be an essential
component for future detectors, while sect. 3 discusses solutions to the
problem of Newtonian noise which arise from fluctuations in gravity gradient
forces acting on test masses. Such gravitational perturbations cannot be
shielded, and set limits to low frequency sensitivity unless measured and
suppressed. Sects. 4 and 5 address critical operational technologies that will
be ongoing issues in future detectors. Sect. 4 addresses the design of thermal
compensation systems needed in all high optical power interferometers operating
at room temperature. Parametric instability control is addressed in sect. 5.
Only recently proven to occur in Advanced LIGO, parametric instability
phenomenon brings both risks and opportunities for future detectors. The path
to future enhancements of detectors will come from quantum measurement
technologies. Sect. 6 focuses on the use of optomechanical devices for
obtaining enhanced sensitivity, while sect. 7 reviews a range of quantum
measurement options
Improvement of Noise and Gain Characteristics of Low-Repetition-Rate Double-Pass Fiber Amplifiers
NMR study of damage on isolated perfused rat heart exposed to ischemia and hypoxia
Myocardial ischemia is the most common and primary cause of myocardium
damage. Numerous conventional techniques and methods have been
developed for ischemia and reperfusion studies. However, because of
damage to the heart sample, most of these techniques can not be used to
continuously monitor the full dynamic course of the myocardial
metabolic pathway. The nuclear magnetic resonnance (NMR) surface coil
technique, which overcomes the limitations of conventional
instrumentation, can be used to quantitatively study every stage of the
perfused heart (especially after perfusion stoppage) continuously,
dynamically, and without damage under normal or designed physiological
conditions at the molecular level. In this paper, 31P -NMR was used to
study the effects of ischemia and hypoxia on isolated perfused hearts.
The results show that complete hypoxia caused more severe functional
damage to the myocardial cells than complete ischemia
The ancient dispersal of millets in southern China: New archaeological evidence
This study presents the first direct evidence of millet cultivation in Neolithic southeast coastal China. Macroscopic plant remains and phytoliths, together with direct accelerator mass spectrometry (AMS) radiocarbon dates on crops, have shown that both foxtail millet and broomcorn millet were cultivated with rice in the Huangguashan and Pingfengshan sites in Fujian province around 4000โ3500 cal. BP. Ratios of different parts of crop remains revealed that crop processing activities such as dehusking and sieving were conducted within the site and thus demonstrated the local production of these crops. The
new data, especially the discovery of foxtail millet and broomcorn millet, have greatly changed the current knowledge about the ancient distribution of millet in South China and have now identified southeast China among the potential source-region of Neolithic crops transported overseas to Taiwan and Island Southeast Asia. This study further draws a potential dispersal route of Austronesian languages and people from southern China through Taiwan
throughout Southeast Asia
Relationships between HDL-C, hs-CRP, with central arterial stiffness in apparently healthy people undergoing a general health examination.
BACKGROUND: Some cardiovascular risk factors have been confirmed to be positively correlated with arterial stiffness. However, it is unclear whether HDL-C, a well-established anti-risk factor, has an independent association with arterial stiffness. The aim of this study was to evaluate the relationship between HDL-C levels and arterial stiffness and the possible role of high-sensitivity C-reactive protein (hs-CRP) in this potential correlation in apparently healthy adults undergoing a general health examination in China. MATERIALS AND METHODS: This was a cross-sectional survey. In total, 15,302 participants (age range, 18-82 years; mean, 43.88ยฑ8.44 years) were recruited during routine health status examinations. A questionnaire was used and we measured the body mass index, systolic and diastolic blood pressure, and fasting glucose, and serum lipid, uric acid, hs-CRP, and serum creatinine levels of each participant. Central arterial stiffness was assessed by carotid-femoral pulse wave velocity (cf-PWV). RESULTS: HDL-C levels decreased as cf-PWV increased. Pearson's correlation analysis revealed that HDL-C levels were associated with cf-PWV (r=-0.18, P<0.001). hs-CRP levels were positively associated with cf-PWV (r=0.13). After adjustment for all confounders, HDL-C was inversely independently associated with all quartiles of cf-PWV. Furthermore, HDL-C was associated with cf-PWV in different quartiles of hs-CRP, and the correlation coefficients (r) gradually decreased with increasing hs-CRP levels (quartiles 1-4). CONCLUSIONS: HDL-C is inversely independently associated with central arterial stiffness. The anti-inflammatory activity of HDL-C may mediate its relationship with cf-PWV. Further, long-term follow-up studies are needed to evaluate whether high HDL-C levels are protective against central artery stiffening through the anti-inflammatory activity of HDL-C
Theoretical and experimental research on cryogenic Yb:YAG regenerative amplifier
ๆฌ็ ็ฉถใฏ, ๅญใฉใใใกใ้ๅใฎไปๆนใใใใใใใใจ, ้ๅๆ่ฝใใฎใฐใใใงใใใใใใซใชใใใจ, ใใใซ, ๅญฆ็ฟใใใใจใใใใใใใใจใงๅญฆใณใๅบใ, ้ๅใซ่ฆชใใใจๅ
ฑใซ, ใใฎๆฅฝใใใๅณใใใใจใใงใใใใใซใใใใ, ใใผใซ้ๅใซใใใใใดใผใซๅใฒใผใ ใใซ็็ฎใ, ๆๆฅญ็ ็ฉถใ่กใฃใใใฎใงใใใ็นใซ, ใดใผใซๅใฒใผใ ใซๅฟ
่ฆใช่ฝๅใ็ฉบ้่ช็ฅๅ(ใฒใผใ ๅ ด้ขใซใใใฆ่ชๅใใใใใฆใใ็ถๆณใ็็ขบใซๅๆใใฆๆๆกใ, ไฝใ้ฉๅใช็ซถๆ่ก็บใใ็ฌๆใซๆฑบๅฎใใ่ฝๅ)ใจ่จญๅฎใใใ่ชๅใใกใฎๅใใๆ ๅใซๆฎใๆฏใ่ฟใฃใใ, ๅญฆ็ฟใใๅใใใฏใผใฏใทใผใใซๆใใใใใใฆๅฐใใใคๆๅนใช็ฉบ้ใซๆฐใฅใใใ, ใใใ็ใใใๅใๆนใซใคใใฆ่ใ, ็่งฃใใใใจใใงใใใใใซใชใ, ไธๅฎใฎๆๆใๅบใใใจใใงใใใใพใ, ใใงใใใใซใคใใฆใใใผใ ใฎไธๅกใจใใฆ่ชๅใฎๆ่ฝใงไฝใใงใใใฎใใใใใใใ่ใๅฎ่ทตใซ็งปใใใจใใงใใใใใซใชใฃใใใใฎไบใซใใฃใฆ็ฉบ้่ช็ฅๅใฎ่ฒๆใจใใ่ฆ็นใงๆๆฅญใๅฑ้ใใฆใใใใจใ, ใดใผใซๅใฎๅญฆ็ฟใซใใใฆ, ้่ฆใงใใใใจใใใใฃใ
Numerical and Experimental Investigation of Morphological Modification on Fused Silica Using CO2 Laser Ablation
In this paper, a numerical model based on the finite-element method for predicting the morphological evolution during CO2 laser ablation on fused silica is developed and examined experimentally. Adopting the optimized parameters that were obtained from the model, a typical cone-shaped multi-stage structure with a diameter of 2 mm and a slope angle of 10.4° was sufficiently polished. Both the roughness and the transparency of the surface structure were significantly improved. The characterized slope angle of the continuous surface is exactly consistent with the predicted value, and the ablation depth is 32 ± 1.247 µm with a deviation of 1.7% (RMS, root mean square). The deviation is principally caused by the neglect of melting displacement in simulation and the irregularity in actual stepping structures. These results indicate that the numerical model can simulate morphological modification of CO2 laser ablation with a high degree of reliability. It could further be used to optimize processing parameters for customizing continuous fused silica surfaces, which could facilitate industrial manufacturing of freeform optics
Experimental Investigations on Wavefront Distortion of LD-Pumped Neodymium-Doped Silica-Glass Rod with High Thermal Shock Parameter
The characterization of a laser diode (LD)-pumped neodymium-doped silica glass (NDSG) laser is here described. The gain performance and wavefront distortion were measured, and the thermal toughness and uniformity distribution of the material were experimentally observed. At a pumping frequency of 1 Hz and energy 7.79 J, a small-signal gain of 1.16 was measured, and the wavefront distortion reached 2.67 λ (wavelength λ = 1053 nm). At a pumping frequency of 25 Hz with 194 W power, the NDSG was still not cracked, which is consistent with its high thermal shock parameter. However, the material uniformity was relatively poor. These results indicate good prospects for the application of NDSG lasers at high energy and high repetition frequency, but the gain performance, uniformity, and other aspects affected by the manufacturing process need to be improved