1
|
Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A. PHYSICAL REVIEW LETTERS 2024; 132:131002. [PMID: 38613275 DOI: 10.1103/physrevlett.132.131002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/23/2024] [Accepted: 02/12/2024] [Indexed: 04/14/2024]
Abstract
We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at 3.67±0.05±0.15 PeV. Below the knee, the spectral index is found to be -2.7413±0.0004±0.0050, while above the knee, it is -3.128±0.005±0.027, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -0.1200±0.0003±0.0341. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components.
Collapse
|
2
|
An E-band multi-channel Doppler backscattering system on EAST. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:123507. [PMID: 38109469 DOI: 10.1063/5.0166949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 11/28/2023] [Indexed: 12/20/2023]
Abstract
An E-band (60-90 GHz) multi-channel Doppler backscattering (DBS) system with X-mode polarization has been installed on the Experimental Advanced Superconducting Tokamak (EAST), which can measure the turbulence at five different radial locations simultaneously. This system can launch 31 fixed microwave frequencies in the range of 60-90 GHz with a 1 GHz interval into the plasma, and five probing signals are selected by employing a reference signal and multiple filters. During experiments, the frequency of the reference signal is tunable in the E-band, and the selected probing signals can be changed as needed without any other adjustments, which can be performed in one shot or between shots. Furthermore, the incident angle can be adjusted from -10° to 20°, and the wavenumber range is 4-25 cm-1 with a wavenumber resolution of Δk/k ≤ 0.35. Ray tracing simulations are employed to calculate the scattering locations and the perpendicular wavenumber. In this article, the hardware design, ray tracing, and initial results obtained from the EAST plasma will be presented.
Collapse
|
3
|
Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A. PHYSICAL REVIEW LETTERS 2023; 131:151001. [PMID: 37897763 DOI: 10.1103/physrevlett.131.151001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/08/2023] [Accepted: 08/18/2023] [Indexed: 10/30/2023]
Abstract
The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°10 TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60 TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.
Collapse
|
4
|
A tera-electron volt afterglow from a narrow jet in an extremely bright gamma-ray burst. Science 2023:eadg9328. [PMID: 37289911 DOI: 10.1126/science.adg9328] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 05/25/2023] [Indexed: 06/10/2023]
Abstract
Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory of the bright GRB 221009A, which serendipitously occurred within the instrument field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger, then rose to a peak about 10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.
Collapse
|
5
|
Search for Spin-Dependent Gravitational Interactions at Earth Range. PHYSICAL REVIEW LETTERS 2023; 130:201401. [PMID: 37267553 DOI: 10.1103/physrevlett.130.201401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 03/06/2023] [Accepted: 03/15/2023] [Indexed: 06/04/2023]
Abstract
Among the four fundamental forces, only gravity does not couple to particle spins according to the general theory of relativity. We test this principle by searching for an anomalous scalar coupling between the neutron spin and the Earth's gravity on the ground. We develop an atomic gas comagnetometer to measure the ratio of nuclear spin-precession frequencies between ^{129}Xe and ^{131}Xe, and search for a change of this ratio to the precision of 10^{-9} as the sensor is flipped in Earth's gravitational field. The null results of this search set an upper limit on the coupling energy between the neutron spin and the gravity on the ground at 5.3×10^{-22} eV (95% confidence level), resulting in a 17-fold improvement over the previous limit. The results can also be used to constrain several other anomalous interactions. In particular, the limit on the coupling strength of axion-mediated monopole-dipole interactions at the range of Earth's radius is improved by a factor of 17.
Collapse
|
6
|
Efficacy of erector spinae nerve block for pain control after lumbar spinal surgeries: a systematic review and meta-analysis. EUROPEAN REVIEW FOR MEDICAL AND PHARMACOLOGICAL SCIENCES 2023; 27:3383-3395. [PMID: 37140288 DOI: 10.26355/eurrev_202304_32109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
OBJECTIVE The review aimed to examine the evidence on the efficacy of erector spinae nerve block (ESPB) for pain control after lumbar spinal surgeries. MATERIALS AND METHODS PubMed, CENTRAL, Embase, and Web of Science were examined for published randomized controlled trials (RCTs) assessing ESPB with control for lumbar spinal surgery patients. The primary review outcome was 24-hour total opioid consumption in morphine equivalents. The secondary review outcomes were pain at rest at 4-6 hours, 8-12 hours, 24 hours and 48 hours, first rescue analgesic timing, needing rescue analgesics number, and postoperative nausea and vomiting (PONV). RESULTS 16 trials were eligible. Total opioid consumption was significantly lower with ESPB as compared to controls (MD: -12.68 95% CI: -18.09, -7.28 I2=99% p<0.00001). Pain scores at 4-6 hours (MD: -1.37 95% CI: -1.98, -0.76 I2=95% p<0.0001), 8-12 hours (MD: -1.18 95% CI:-1.84, -0.52 I2=98% p=0.0004), 24 hours (MD: -0.53 95% CI:-1.03, -0.04 I2=96% p=0.04) and 48 hours (MD: -0.36 95% CI:-0.84, 0.13 I2=88% p=0.15) were significantly lower in the ESPB group. The meta-analysis found that the ESPB group required a significantly longer time for the first analgesic request (MD: 5.26 95% CI: 2.53, 7.99 I2=100% p=0.002), had lower demand for rescue analgesics (OR: 0.12 95% CI: 0.07, 0.21 I2=2% p<0.00001) and fewer incidence of PONV (OR: 0.27 95% CI: 0.15, 0.49 I2=51% p<0.0001). CONCLUSIONS ESPB can be highly efficacious for postoperative analgesia in lumbar surgery patients. The block has the capability of reducing opioid consumption in the first 24 hours and pain scores up to 48 hours along with a significant reduction in the need for rescue analgesics and PONV.
Collapse
|
7
|
Insomnia and multiple health outcomes: umbrella review of meta-analyses of prospective cohort studies. Public Health 2023; 215:66-74. [PMID: 36645961 DOI: 10.1016/j.puhe.2022.11.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 09/17/2022] [Accepted: 11/28/2022] [Indexed: 01/15/2023]
Abstract
OBJECTIVES To evaluate existing evidence of prospective cohort studies on associations between insomnia and multiple health outcomes. STUDY DESIGN An umbrella review of meta-analyses of prospective cohort studies. METHODS A systematic search was undertaken in Pubmed, Embase, Cochrane, and Web of Science from inception to October 2021 to find meta-analyses of prospective cohort studies investigating the association of insomnia with any health outcome. The summary relative risk (SRR) for each meta-analysis was recalculated with random-effects model. The methodological quality and the quality of evidence were assessed by the A Measurement Tool to Assess Systematic Reviews and Grading of Recommendations, Assessment, Development and Evaluation, respectively. RESULTS A total of 25 published meta-analyses of prospective cohort studies, reporting 63 SRRs for 29 unique outcomes were included. Insomnia was mainly related to cardiovascular outcomes and mental disorders. The former comprised atrial fibrillation (SRR: 1.30, 95% confidence interval: 1.26 to 1.35), cardiovascular diseases (1.45, 1.29 to 1.64), coronary heart disease (1.28, 1.10 to 1.50), myocardial infarction (1.42, 1.17 to 1.72), and stroke (1.55, 1.39 to 1.72). The latter involved alcohol abuse (1.35, 1.08 to 1.67), all mental disorders (2.16, 1.70 to 3.97), anxiety (3.23, 1.52 to 6.85), depression (2.31, 1.90 to 2.81), suicidal ideation (2.26, 1.79 to 2.86), suicidal attempt (1.99, 1.31 to 3.02), and suicidal death (1.72, 1.42 to 2.08). Besides, insomnia enhanced the risk of Alzheimer's disease (1.51, 1.06 to 2.14) and hyperlipidemia (1.64, 1.53 to 1.76). CONCLUSION Insomnia exhibits considerable adverse outcomes, primarily comprises cardiovascular outcomes and mental disorders, but further studies with robustly designed trials are needed to draw firmer conclusions.
Collapse
|
8
|
[A preliminary study on the prevention of hemorrhage after laparoscopic pancreaticoduodenectomy by wrapping gastroduodenal artery stump in the left external liver lobe and the left caudate lobe]. ZHONGHUA WAI KE ZA ZHI [CHINESE JOURNAL OF SURGERY] 2023; 61:145-149. [PMID: 36720624 DOI: 10.3760/cma.j.cn112139-20220623-00280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Objective: To investigate the safety and efficacy of embedding the stump of gastroduodenal artery between the left lateral lobe of the liver and the left caudate lobe to prevent bleeding after laparoscopic pancreaticoduodenectomy. Methods: The clinical data of 41 patients who underwent laparoscopic pancreaticoduodenectomy at the second Hospital of Hebei Medical University from October 2021 to April 2022 were analyzed retrospectively.There were 27 males and 14 females, aged (63.0±9.2)years (range: 48 to 78 years), and the body mass index was (24.1±3.2)kg/m2 (range: 15.4 to 31.6 kg/m2). After routine laparoscopic pancreaticoduodenectomy, the stump of gastroduodenal artery was embedded between the left lateral lobe and the left caudate lobe of the liver, and the hepatic parenchyma of the left lateral lobe and the left caudate lobe were sutured with absorbable sutures.The occurrence and recovery of postoperative complications (pancreatic fistula, biliary fistula, postoperative abdominal bleeding, abdominal infection, liver abscess) were observed. Results: All the operations of 41 patients were completed successfully.The operation time was (277.5±52.0) minutes (range: 192 to 360 minutes). The entrapment time of gastroduodenal artery stump was (3.1±0.6) minutes (range: 2.3 to 4.2 minutes), and the intraoperative blood loss (M(IQR)) was 300 (200) ml (range: 50 to 800 ml).The results of ultrasound examination of hepatic artery on the first day after operation showed that the blood flows of hepatic artery were unobstructed.Postoperative pancreatic fistula occurred in 3 cases, including grade B pancreatic fistula in 2 cases (1 case with abdominal infection) and biochemical leakage in 1 case. Three patients with pancreatic fistula were discharged successfully after continuous abdominal drainage. There was no biliary fistula, abdominal bleeding, abdominal infection, liver abscess or postoperative liver dysfunction. Conclusion: The encasement of the gastroduodenal artery stump by the left outer and left caudate lobes of the liver may be an effective way to prevent bleeding from the rupture of the gastroduodenal artery stump after laparoscopic pancreatoduodenectomy, which is easy and safe to perform.
Collapse
|
9
|
Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations. PHYSICAL REVIEW LETTERS 2022; 129:261103. [PMID: 36608208 DOI: 10.1103/physrevlett.129.261103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 08/19/2022] [Accepted: 10/27/2022] [Indexed: 06/17/2023]
Abstract
The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9} GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.
Collapse
|
10
|
Search for Monopole-Dipole Interactions at the Submillimeter Range with a ^{129}Xe-^{131}Xe-Rb Comagnetometer. PHYSICAL REVIEW LETTERS 2022; 128:231803. [PMID: 35749169 DOI: 10.1103/physrevlett.128.231803] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Monopole-dipole interactions involving scalar couplings between a spin and a massive particle violate both P and T symmetry, and can be mediated by axions. We use a ^{129}Xe-^{131}Xe-Rb atomic cell comagnetometer to measure the ratio of precession frequencies between the two xenon isotopes, and search for changes of the ratio correlated with the distance between the atomic cell and a nonmagnetic bismuth germanate crystal. A modulated Rb polarization scheme is used to suppress systematic effects by 2 orders of magnitude. The null results of this search improve the upper limit on the coupling strength g_{s}^{N}g_{p}^{n} over the interaction range 0.11-0.55 mm, and by a maximum improvement factor of 30 at 0.24 mm. The corresponding propagator mass range of this new excluded region covers 0.36-1.80 meV.
Collapse
|
11
|
[Consideration on implementation of co-administration of Seasonal Influenza and COVID-19 vaccines during pandemic in China]. ZHONGHUA YU FANG YI XUE ZA ZHI [CHINESE JOURNAL OF PREVENTIVE MEDICINE] 2022; 56:103-107. [PMID: 34954956 DOI: 10.3760/cma.j.cn112150-20211203-01117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Influenza is an infectious respiratory disease caused by the influenza viruses. Older people, infants and people with underlying medical conditions could have a higher risk of severe influenza symptoms and complications. The co-infection of Coronavirus Diseases 2019 (COVID-19) with influenza viruses could lead to the complication of prevention, diagnosis, control, treatment, and recovery of COVID-19. Influenza vaccine and COVID-19 vaccine overlapped in target populations, vaccination time, and inoculation units. Although there was insufficient evidence on the immunogenicity and safety of co-administration of influenza vaccine and COVID-19 vaccine, World Health Organization and some countries recommended co-administration of inactivated influenza vaccine and COVID-19 vaccine. This review summarized domestic and international vaccination policies and research progress, and put forward corresponding suggestions in order to provide scientific support for the formulation of vaccination strategy on seasonal influenza vaccine and COVID-19 vaccine.
Collapse
|
12
|
Vitamin D inadequacy combined with high BMI affects paraspinal muscle atrophy and pain intensity in postmenopausal women. Climacteric 2021; 25:376-382. [PMID: 34694955 DOI: 10.1080/13697137.2021.1990257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE This study was performed to assess the effects of vitamin D deficiency/insufficiency combined with a high body mass index (BMI) on paraspinal muscle (PSM) atrophy and pain intensity in postmenopausal women with lower back pain (LBP). METHODS In total, 365 postmenopausal women were analyzed in the study. We divided the women into four groups according to BMI and vitamin D status. Outcome measurements included PSM atrophy, fatty infiltration (FI) and severity of LBP. Binary logistic regression was used to analyze the odds ratio (OR), and the interaction between the BMI and vitamin D status was tested. RESULTS Compared with the control group, the high BMI with vitamin D deficiency/insufficiency group had a significantly increased risk of FI > grade 2 (OR = 10.69, p < 0.001), hand grip strength of <16 kg (OR = 8.96, p < 0.001), Short Physical Performance Battery score of ≤8 (OR = 3.69, p < 0.001) and visual analog scale (VAS) score of >3 (OR = 4.76, p < 0.001). A significant positive additive interaction was found between the BMI and vitamin D status on PSM atrophy. CONCLUSION Vitamin D deficiency/insufficiency combined with a high BMI was associated with PSM atrophy and LBP intensity in postmenopausal women. The interaction analysis showed a positive additive interaction between BMI and vitamin D status.
Collapse
|
13
|
Application of random sample consensus method for parameter estimation of reflectometry density profile in toroidal plasma. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:043521. [PMID: 34243453 DOI: 10.1063/5.0035962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 03/23/2021] [Indexed: 06/13/2023]
Abstract
Microwave reflectometry diagnostics have been widely used to measure density profiles in fusion plasma. However, the high sensitivity of the diagnostics to plasma turbulence often results in large radial deviations in the edge density profile and causes difficulty in profile evaluation. To improve the performance of profile evaluation, a modified RANdom SAmple Consensus (RANSAC) method has been applied to fit the density profiles measured by reflectometry on the experimental advanced superconducting tokamak. Compared with the traditional least-squares method, the modified RANSAC method is much more efficient and robust in fitting the experimental profiles. Furthermore, a combination of RANSAC and a genetic algorithm (GA-RANSAC) is used to further optimize the profile evaluation procedure. The results show that this GA-RANSAC method yields better performance and stabler convergence than the modified RANSAC alone.
Collapse
|
14
|
The cross-polarization scattering system for the magnetic fluctuation measurement in the Experimental Advanced Superconducting Tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:043511. [PMID: 34243396 DOI: 10.1063/5.0012520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 03/16/2021] [Indexed: 06/13/2023]
Abstract
The cross-polarization scattering (CPS) system for magnetic fluctuation measurements in the Experimental Advanced Superconducting Tokamak (EAST) has been designed and installed. Different from the Doppler reflectometer (DR) system, the CPS system detects the perpendicular polarization of the electromagnetic wave induced by magnetic fluctuations B̃. The CPS system in the EAST has been developed from the existing Doppler reflectometer system, and they are integrated together for simultaneous measurement of magnetic and density fluctuations. Ray-tracing simulations are used to calculate the scattering locations and the wavenumber coverage of the magnetic fluctuation for CPS. In the experiments, the CPS and DR system data were different in Doppler shift, amplitude, and spectrum broadening. In this article, the hardware design, the ray tracing, and the preliminary results of the system in the EAST are presented.
Collapse
|
15
|
[Application and status of digestive endoscopy in the overall management of portal hypertension-related esophagogastric variceal bleeding]. ZHONGHUA GAN ZANG BING ZA ZHI = ZHONGHUA GANZANGBING ZAZHI = CHINESE JOURNAL OF HEPATOLOGY 2020; 28:732-736. [PMID: 33053971 DOI: 10.3760/cma.j.cn501113-20200602-00287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Portal hypertension-related esophagogastric variceal bleeding (EVB) is deadly. Therefore, multidisciplinary management involving hepatologists, digestive endoscopy, radiological intervention, and/or surgery is necessary. Digestive endoscopy is the core of the multidisciplinary approach to the overall management of portal hypertension. It plays an important role in the early warning, emergency treatment, and the prevention of the initial and re-bleeding of portal hypertension accompanied by esophagogastric varices. In addition, gastroscopy with endoscopic ultrasound scanning can enhance the management capabilities of ectopic varices.
Collapse
|
16
|
Therapeutic effect of dexmedetomidine on intracerebral hemorrhage via regulating NLRP3. EUROPEAN REVIEW FOR MEDICAL AND PHARMACOLOGICAL SCIENCES 2020; 23:2612-2619. [PMID: 30964190 DOI: 10.26355/eurrev_201903_17411] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE To investigate the protective effect of dexmedetomidine on intracerebral hemorrhage (ICH) mice and the underlying mechanism. MATERIALS AND METHODS The in vivo ICH model was induced by the injection of autologous blood in C57BL/6 mice. Mice were randomly assigned into control group (no specific treatment) and treatment group (dexmedetomidine administration). Mouse neuronal deficits were evaluated by modified neurological severity scores (mNSS) and Corner Turn Test. ICH volume and cerebral edema at the hemisphere of lesions were determined. Inflammatory response at post-ICH was examined by flow cytometry and quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The integrity and permeability of blood brain barrier (BBB) were detected by Western blot and Evans Blue extravasation. RESULTS Dexmedetomidine treatment markedly alleviated the clinical symptoms of ICH mice, and decreased ICH volume and cerebral edema. QRT-PCR data revealed down-regulated levels of NLRP3, ASC, Caspase-1, and IL-1β in mice of the treatment group relative to controls. Moreover, dexmedetomidine administration decreased contents of CD11b+CD45int, IL-6, and IL-1β, but elevated TGF-β content in treatment group. The Evans Blue leakage was reduced in mice of the treatment group. Both protein and mRNA levels of Claudin-5 and ZO-1 were upregulated in the treatment group. CONCLUSIONS Dexmedetomidine remarkably inhibits the activation of inflammasome, alleviates secondary cerebral injury and inflammation, and protects the integrity and permeability of BBB at post-ICH.
Collapse
|
17
|
[Analysis of transmission characteristics of COVID-19 in Shaanxi Province]. ZHONGHUA YU FANG YI XUE ZA ZHI [CHINESE JOURNAL OF PREVENTIVE MEDICINE] 2020; 54:493-497. [PMID: 32388948 DOI: 10.3760/cma.j.cn112150-20200227-00201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A total of 245 cases of COVID-19 in Shaanxi Province reported in the China information system for disease control and prevention as of February 24, 2020 were selected as the research objects, the cases are divided into imported cases (116 cases, 47.3%) and local cases (129 cases, 52.7%), their basic characteristics, time distribution, transmission mode, intergenerational interval and latent period transmission are analyzed. The age of local cases [(51.74±15.67) years old], female patients (69 cases, 53.5%), housework and retired staff (40 cases, 31.0%), and patients isolated at the time of onset (50 cases, 38.8%) were higher than imported cases, respectively[(40.66±15.41) years old, (45 cases, 38.8%), (21 cases, 18.1%), (17 cases, 14.6%)] (P values were < 0.05); The infection rate was 0.8% (31/3 666) in close contacts with local cases, which was lower than imported cases 2.0% (69/3 435) (P<0.001); The main source of infection in local cases was relatives (70 cases, 54.3%), and the main way of infection was living together and party (90 cases, 69.8%); the proportion of latent period transmission in our province was 15.5% (20 cases), and the interval between the second-generation case and the source of infection was about 4 days, and the interval between generations was about 6 days. In summary, the main way of infection of local cases in Shaanxi Province was living together and party, there were a certain proportion of latent period transmission cases at present, it's suggested that the investigation of close contacts should be started 4 days or earlier before the onset of the case.
Collapse
|
18
|
Abstract
Resveratrol (RES) is a naturally occurring and effective drug for tumor prevention and treatment. However, its low levels of aqueous solubility, stability, and poor bioavailability limit its application, especially when used as a free drug. In this study, RES was loaded into peptide and sucrose liposomes (PSL) to enhance the physico-chemical properties of RES and exploit RES delivery mediated by liposomes to effectively treat breast cancer. RES loaded PSL (the complex: PSL@RES) were stable, had a good RES encapsulation efficiency, and prolonged RES-release in vitro. PSL@RES was exceptionally efficient for inhibiting the growth of cancer cells, as the IC50 of PSL@RES in MCF-7 cells was found to be only 20.89 μmol L-1. The therapeutic efficacy of PSL@RES was evaluated in mice bearing breast cancer. The results showed that PSL@RES at a dosage of 5 mg kg-1 was more effective than 10 mg kg-1 free RES, and PSL@RES inhibited tumor growth completely at a dosage of 10 mg kg-1. PSL@RES induced apoptosis in breast tumor by upregulation of p53 expression. This then downregulated Bcl-2 and upregulated Bax, thereby inducing Caspase-3 activation. More importantly, encapsulation of RES within peptide liposomes greatly reduced the toxicity of free RES to mice. Overall, the simple formulation of liposomal nanocarriers of RES developed in this study produces satisfactory outcomes to encourage further applications of liposomal carriers for the treatment of breast cancer.
Collapse
|
19
|
[China Hainan Centenarian Cohort Study: study design and preliminary results]. ZHONGHUA LIU XING BING XUE ZA ZHI = ZHONGHUA LIUXINGBINGXUE ZAZHI 2019; 38:1292-1298. [PMID: 28910949 DOI: 10.3760/cma.j.issn.0254-6450.2017.09.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Objective: To investigate the health status, functional ability, mental psychology, health care and other longevity-related characteristics of individuals aged ≥100 years as well as risk factors in Hainan province, China. Methods: China Hainan Centenarian Cohort Study (CHCCS) is a community-based, prospective cohort study to establish multi-dimensional database consisting of questionnaire findings, anthropometric parameters and biological specimens as well as imaging features. With the household registration information provided by the Department of Civil Affairs of Hainan province, a baseline survey was conducted in centenarians in 18 counties in Hainan with the oldest old in 5 counties as controls between 2014 and 2017. The survey included face to face interview, physical examination and biological specimen collection. After the baseline survey, the participants of CHCCS were followed up at an interval of 2 years to collect the information about their living status, disease status or major death causes. Results: According to the information provided by the Department of Civil Affairs of Hainan province in 2014, the survey found that 1 473 centenarians were still living. By December 2016, 1 002 of them had agreed to be surveyed. The average age of 722 centenarians with complete information in the baseline survey was (102.7±2.7) years, the majority of them were females (83.0%), widows (88.8%), in Han ethnic group (84.5%), lived with family members (87.8%), illiterates (89.7%) and farmers (81.0%). Conclusion: CHCCS has provided longevity-related information of the large longevity population and collected the valuable and rare biological specimens with great urgency to establish an interdisciplinary platform and base for longevity, senility and healthy aging research.
Collapse
|
20
|
Effective chemical potential for non-equilibrium systems and its application to molecular beam epitaxy of Bi 2Se 3. NANOSCALE ADVANCES 2019; 1:470-475. [PMID: 36132266 PMCID: PMC9473254 DOI: 10.1039/c8na00136g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 09/29/2018] [Indexed: 05/31/2023]
Abstract
First-principles studies often rely on the assumption of equilibrium, which can be a poor approximation, e.g., for growth. Here, an effective chemical potential ([italic small mu, Greek, macron]) method for non-equilibrium systems is developed. A salient feature of the theory is that it maintains the equilibrium limits as the correct limit. In application to molecular beam epitaxy, rate equations are solved for the concentrations of small clusters, which serve as feedstock for growth. We find that [italic small mu, Greek, macron] is determined by the most probable, rather than by the lowest-energy, cluster. In the case of Bi2Se3, [italic small mu, Greek, macron] is found to be highly supersaturated, leading to a high nucleus concentration in agreement with experiment.
Collapse
|
21
|
Five-channel tunable W-band Doppler backscattering system in the experimental advanced superconducting tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:024704. [PMID: 30831725 DOI: 10.1063/1.5075615] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 01/18/2019] [Indexed: 06/09/2023]
Abstract
A 5-channel Doppler backscattering system has been designed and installed in the Experimental Advanced Superconducting Tokamak (EAST). Through an I/Q-type double sideband modulator and a frequency multiplier, an array of finely spaced (Δf = 400 MHz) frequencies that span 1.6 GHz has been created. The center of the array bandwidth is tunable within the range of 75-97.8 GHz, which covers most of the W band (75-110 GHz). The incident angle can be adjusted from -4° to 12°, and the wavenumber range is 4-15 cm-1 with a wavenumber resolution of Δk/k ≤ 0.35. Ray tracing is used to calculate the scattering location and the scattering wavenumber. This article details the hardware design, the ray tracing, and the preliminary experimental results from EAST plasmas.
Collapse
|
22
|
[A case of acute myocardial infarction and cardiac shock due to severe coronary arteryspasm]. ZHONGHUA XIN XUE GUAN BING ZA ZHI 2018; 46:903-904. [PMID: 30462981 DOI: 10.3760/cma.j.issn.0253-3758.2018.11.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
|
23
|
Development of an ordinary mode multi-channel correlation reflectometer on EAST tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10H103. [PMID: 30399842 DOI: 10.1063/1.5035445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 05/27/2018] [Indexed: 06/08/2023]
Abstract
An ordinary-mode polarized multi-channel correlation reflectometer has been developed on the Experimental Advanced Superconducting Tokamak (EAST). The system with four different probing frequencies (i.e., 20.4 GHz, 24.8 GHz, 33 GHz, and 40 GHz) and two poloidally spaced receiving antennas can realize both the radial correlation measurement and the poloidal correlation measurement. These diagnostics focus on the measurement of density fluctuation in the pedestal region to investigate the turbulence transport and H-mode physics on EAST. In this article, the system hardware design, the key component tests, and the system performance are shown in detail.
Collapse
|
24
|
First Report of Capsicum chlorosis orthotospovirus Infecting Zucchini (Cucurbita pepo) in China. PLANT DISEASE 2018; 102:PDIS12171876PDN. [PMID: 30110247 DOI: 10.1094/pdis-12-17-1876-pdn] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
|
25
|
[Quality of case report of Japanese Encephalitis after the establishment of surveillance on acute meningitis and encephalitis syndrome in Baoji]. ZHONGHUA YU FANG YI XUE ZA ZHI [CHINESE JOURNAL OF PREVENTIVE MEDICINE] 2017; 51:821-826. [PMID: 28881548 DOI: 10.3760/cma.j.issn.0253-9624.2017.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Objective: To evaluate the quality of Japanese Encephalitis (JE) case reports based on the establishment of surveillance on acute meningitis and encephalitis syndrome (AMES) in Baoji. Methods: A surveillance network on AMES cases was set up in Baoji city of Shaanxi province between July 2013 and December 2016. All the cases met the surveillance definition of AMES cases were conducted a questionnaire, collected serum and/or cerebrospinal fluid (CSF) specimens to test JE immunoglobulin M antibodies by using enzyme-linkedimmunosorbent assay methods.The information of the incidence of JE in Shaanxi and Baoji from 2009 to 2016 originated from the China information system for disease control and prevention. Chi square test was used to compare the difference in JE incidence in Baoji, Shaanxi before and after the implementation of AMES monitoring project. Results: 75 out of 855 collected cases were laboratory confirmed as JE, Including 42 suspected JE cases and 33 other suspected cases diagnosed after hospitalization. Except 1 case occurring in December, all the other cases occurred between July and October, especially in August with a peak of 55 cases (73.3%), and 6 cases (8.0%) in July, 11 cases (14.7%) in September, 2 cases (2.7%) in October. The proportion of patients aging 0-6, 7-14 and ≥15 years old were respectively 4.0% (3 cases), 8.0% (6 cases) and 88.0% (66 cases). The biochemical test showed the cerebrospinal fluid in 13 cases (17.3%) were slightly turbid, the white blood cell in 31 cases (41.3%) elevated, the glucose levels in 24 cases (32.0%) were abnormal, and the chloride level in 23 cases (30.7%) were abnormal. A total of 103 cases of JE were diagnosed in Baoji from 2009 to 2016, with an average annual incidence rate at 0.34/100 000. The average incidence of JE in 2009-2012 and 2013-2016 was 0.21/100 000 and 0.48/100 000 respectively. From 2013 to 2016, the proportion of JE cases in Baoji, Shaanxi was 19.3% (71/369), and it was 8.9% (32/362) between 2009 and 2012 (χ(2)=4.15, P=0.040). Conclusion: The AMES surveillance project improved the quality of the JE case report in Baoji. Changes appeared in biochemistrical and epidemiological characteristics of cerebrospinal fluid. The incidence of JE was seriously underestimated in Shaanxi province and therefore the sensitivity of Japanese encephalitis surveillance cases should be further improved.
Collapse
|
26
|
[Ten-day Periodical of Traditional Chinese Medicine and its concept of confluence of Chinese and western medicine]. ZHONGHUA YI SHI ZA ZHI (BEIJING, CHINA : 1980) 2016; 46:285-288. [PMID: 28104002 DOI: 10.3760/cma.j.issn.0255-7053.2016.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The Ten-day Periodical of Traditional Chinese Medicine, a TCM Journal founded by the Xiamen Professional School of Traditional Chinese Medicine in July 1934, had published a lot of essays written by many TCM physicians that interpret the concept of traditional Chinese medicine by western medicine, offering the academic way of probing confluence of Chinese and Western Medicine in Xiamen. The aim of the Journal includes "developing TCM academy" and the "confluence of TCM with western medicine" , the exploration of TCM and the penetration of Chinese and western medicine, and getting rid of blind faith on "science" to set up the belief of TCM and to prove the ideas of visceral theory and its gasification by the anatomical knowledge of western medicine. The Journal envisaged the difference between the TCM and WM, avoided blind convergence, representing the academic inheritance and progress of the era. Although the essays published might have made a forced analogy by over-praising TCM, however, its exploration and convergence of TCM and the experiences are helpful to modern scholars to properly manage the relation of TCM and WM to face the future challenge consciously.
Collapse
|
27
|
Carrier-Multiplication-Induced Structural Change during Ultrafast Carrier Relaxation and Nonthermal Phase Transition in Semiconductors. PHYSICAL REVIEW LETTERS 2016; 117:126402. [PMID: 27689286 DOI: 10.1103/physrevlett.117.126402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Indexed: 06/06/2023]
Abstract
While being extensively studied as an important physical process to alter exciton population in nanostructures at the fs time scale, carrier multiplication has not been considered seriously as a major mechanism for phase transition. Real-time time-dependent density functional theory study of Ge_{2}Sb_{2}Te_{5} reveals that carrier multiplication can induce an ultrafast phase transition in the solid state despite that the lattice remains cold. The results also unify the experimental findings in other semiconductors for which the explanation remains to be the 30-year old phenomenological plasma annealing model.
Collapse
|
28
|
Toward the Intrinsic Limit of the Topological Insulator Bi_{2}Se_{3}. PHYSICAL REVIEW LETTERS 2016; 117:106401. [PMID: 27636482 DOI: 10.1103/physrevlett.117.106401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Indexed: 06/06/2023]
Abstract
Combining high resolution scanning tunneling microscopy and first principles calculations, we identified the major native defects, in particular the Se vacancies and Se interstitial defects, that are responsible for the bulk conduction and nanoscale potential fluctuations in single crystals of archetypal topological insulator Bi_{2}Se_{3}. Here it is established that the defect concentrations in Bi_{2}Se_{3} are far above the thermodynamic limit, and that the growth kinetics dominate the observed defect concentrations. Furthermore, through careful control of the synthesis, our tunneling spectroscopy suggests that our best samples are approaching the intrinsic limit with the Fermi level inside the band gap without introducing extrinsic dopants.
Collapse
|
29
|
High-Temperature Quantum Anomalous Hall Effect in n-p Codoped Topological Insulators. PHYSICAL REVIEW LETTERS 2016; 117:056804. [PMID: 27517787 DOI: 10.1103/physrevlett.117.056804] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Indexed: 06/06/2023]
Abstract
The quantum anomalous Hall effect (QAHE) is a fundamental quantum transport phenomenon that manifests as a quantized transverse conductance in response to a longitudinally applied electric field in the absence of an external magnetic field, and it promises to have immense application potential in future dissipationless quantum electronics. Here, we present a novel kinetic pathway to realize the QAHE at high temperatures by n-p codoping of three-dimensional topological insulators. We provide a proof-of-principle numerical demonstration of this approach using vanadium-iodine (V-I) codoped Sb_{2}Te_{3} and demonstrate that, strikingly, even at low concentrations of ∼2% V and ∼1% I, the system exhibits a quantized Hall conductance, the telltale hallmark of QAHE, at temperatures of at least ∼50 K, which is 3 orders of magnitude higher than the typical temperatures at which it has been realized to date. The underlying physical factor enabling this dramatic improvement is tied to the largely preserved intrinsic band gap of the host system upon compensated n-p codoping. The proposed approach is conceptually general and may shed new light in experimental realization of high-temperature QAHE.
Collapse
|
30
|
[The clinical application of tinnitus handicap index(THI-12) Chinese version]. LIN CHUANG ER BI YAN HOU TOU JING WAI KE ZA ZHI = JOURNAL OF CLINICAL OTORHINOLARYNGOLOGY, HEAD, AND NECK SURGERY 2016; 30:907-910. [PMID: 29797940 DOI: 10.13201/j.issn.1001-1781.2016.11.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Indexed: 11/12/2022]
Abstract
Objective:The original prospective of this study is to explore a convenient tinnitus severity assessment tool, using Chinese version of THI-12.Method:We surveyed 229 outpatients on their first hospital visits with primary tinnitus as chief complaint. Both the Chinese version THI-12 and the standard THI-25 were administrated. Their tinnitus grading and administration time were compared. The correlation between the two scores was evaluated. A reliability and factor analysis of the Chinese version of THI-12 was also performed.Result:Two hundred and fifteen of the 229 questionnaires were valid with a 93.9% response rate. The average administration time was(18.9±21.0) min for the standard THI-25 and(8.96±4.70)min for the Chinese version THI-12, which was significantly different. Pearson's correlation coefficient between the two total scores was r=0.833(P <0.01), which indicates a strong positive correlation.The tinnitus grading was not statistically significant(Z=-0.307,P >0.05).Cronbach's coefficient of THI-12 was α=0.765, suggesting good reliability and internal consistency. Factor analysis found three entries with characteristic values greater than 1. These three common factors explained 51.77% of the overall variance, suggesting that the 12 entries can be grouped into three dimensions(emotionality, sociality, concentration). Entry"Because of your tinnitus is it difficult for you to concentrate? "had the highest common value(0.78), suggesting that this entry would contribute the most should all entries be divided into three dimensions.Conclusion:The Chinese version THI-12 is time-efficient, has good reliability and internal structural validity, and provides good assessment of tinnitus severity.It can be widely applied in clinical practice.
Collapse
|
31
|
Towards three-dimensional Weyl-surface semimetals in graphene networks. NANOSCALE 2016; 8:7232-7239. [PMID: 26971563 DOI: 10.1039/c6nr00882h] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Graphene as a two-dimensional topological semimetal has attracted much attention for its outstanding properties. In contrast, three-dimensional (3D) topological semimetals of carbon are still rare. Searching for such materials with salient physics has become a new direction in carbon research. Here, using first-principles calculations and tight-binding modeling, we propose a new class of Weyl semimetals based on three types of 3D graphene networks. In the band structures of these materials, two flat Weyl surfaces appear in the Brillouin zone, which straddle the Fermi level and are robust against external strain. Their unique atomic and electronic structures enable applications in correlated electronics, as well as in energy storage, molecular sieves, and catalysis. When the networks are cut, the resulting slabs and nanowires remain semimetallic with Weyl lines and points at the Fermi surfaces, respectively. Between the Weyl lines, flat surface bands emerge with possible strong magnetism. The robustness of these structures can be traced back to a bulk topological invariant, ensured by the sublattice symmetry, and to the one-dimensional Weyl semimetal behavior of the zigzag carbon chain.
Collapse
|
32
|
Determination of formation and ionization energies of charged defects in two-dimensional materials. PHYSICAL REVIEW LETTERS 2015; 114:196801. [PMID: 26024189 DOI: 10.1103/physrevlett.114.196801] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Indexed: 06/04/2023]
Abstract
We present a simple and efficient approach to evaluate the formation energy and, in particular, the ionization energy (IE) of charged defects in two-dimensional (2D) systems using the supercell approximation. So far, first-principles results for such systems can scatter widely due to the divergence of the Coulomb energy with vacuum dimension, denoted here as L_{z}. Numerous attempts have been made in the past to fix the problem under various approximations. Here, we show that the problem can be resolved without any such assumption, and a converged IE can be obtained by an extrapolation of the asymptotic IE expression at large L_{z} (with a fixed lateral area S) back to the value at L_{z}=0. Application to defects in monolayer boron nitride reveal that defects in 2D systems can be unexpectedly deep, much deeper than the bulk.
Collapse
|
33
|
Microscopic origin for the orientation dependence of NV centers in chemical-vapor-deposited diamond. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:485004. [PMID: 25341617 DOI: 10.1088/0953-8984/26/48/485004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
First-principles calculation reveals that hydrogen, which is abundant in chemical vapor deposition (CVD), can significantly improve the uniformity of nitrogen-vacancy (NV) centers in diamond. It shows that the formation of NV centers can be described as a multi-step process: first, a substitutional N (NC) is preferentially formed at the surface layer over that of either a carbon vacancy (VC) or an in-pane nitrogen-vacancy-hydrogen (NVH) complex. Second, with the help of H, a VC is preferentially incorporated in the newly formed topmost layer as a nearest neighbor to the NC (now buried in the first sublayer). This NVH complex is even more stable than NC on the same layer. Third, H protects the already formed NV centers by forming low-energy NVHX complexes. These NV centers with their axes pointing along the directions of surface C-H bonds during their incorporation explain the experimental observations by CVD growth on (1 0 0) and (1 1 0) surfaces. Based on the model, we predict that CVD growth on (1 1 1) surface could eliminate the orientation domains to significantly improve the performance of NV centers.
Collapse
|
34
|
First Report of Sweet potato leaf curl Georgia virus Infecting Tall Morning Glory (Ipomoea purpurea) in China. PLANT DISEASE 2014; 98:1588. [PMID: 30699798 DOI: 10.1094/pdis-11-13-1161-pdn] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In September 2013, tall morning glory (Ipomoea purpurea) plants showing vein yellowing and leaf curl symptoms typical of a begomovirus infection were observed in Jingzhou, Hubei Province, China. Total nucleic acids were extracted from a symptomatic plant using cetyltrimethylammonium bromide (CTAB). Rolling circle amplification (RCA) was conducted using TempliPhi kit (GE Healthcare) to recover the genome of a putative begomovirus. Digestion of the RCA product with PstI yielded a ~2.8 kbp DNA fragment suggestive of a monomerized begomoviral genome. The fragment was cloned and sequenced and the sequence was deposited in GenBank under accession no. KF769447. SDTv1.0 (species demarcation tool) analysis revealed that the putative begomovirus showed 98.5 and 92.0% nucleotide sequence identity with Sweet potato leaf curl Georgia virus (SPLCGV)-[China:Hebei:2011] (GenBank Accession No. JX448368) and SPLCGV-[US:Geo:16] (AF326775), respectively. The virus contained six ORFs, which encoded proteins showing 96.5 to 100% and 90.6 to 95.6% amino acid sequence identity with their counterparts of SPLCGV-[China:Hebei:2011] and SPLCGV-[US:Geo:16], respectively. Thus, the virus should be considered as an isolate of SPLCGV-[China:Hebei:2011]. Tall glory morning in a nearby field (which covers an area of 3 square kilometers) was surveyed and 70 to 100% of plants were found showing symptoms reminiscent of begomoviral infection. Total nucleic acid was extracted from 13 randomly selected (10 symptomatic and 3 healthy) plants and used as templates for PCR with a pair of specific primers (5'-CGCAGCCTTTCCACACTATC-3'/5'-AAAACAGTTTGGGCTCGGTC-3') designed according to the sequence described above. Positive results were obtained for all of the symptomatic, but none of the healthy-looking tall morning glory plants. SPLCGV (genus Begomovirus, family Geminiviridae) was reported to infect sweet potato (I. batatas) in the United States (4), India (2), and China (3). To our knowledge, this is the first report of SPLCGV infecting tall morning glory in China. Also, it is the first report of a geminivirus in Hubei, a province of central China. Whereas the finding of SPLCGV in sweet potato (3) may be a result of vegetative propagation of this crop, the detection of SPLCGV in tall morning glory, an annual plant, raises the possibility that this virus is transmissible and is spreading in China. References: (1) B. Muhire et al. Arch. Virol. 158:1411, 2013. (2) G. Prasanth and V. Hegde. Plant Dis. 92:311, 2008. (3) Y. Qin et al. Plant Dis. 97:1388, 2013. (4) R. A. Valverde and D. L. Gutierrez. Rev. Mex. Fitopatol. 21:128, 2003.
Collapse
|
35
|
Theory of oxygen-boron vacancy defect in cubic boron nitride: a diamond NV⁻ isoelectronic center. PHYSICAL REVIEW LETTERS 2014; 113:136401. [PMID: 25302909 DOI: 10.1103/physrevlett.113.136401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Indexed: 05/12/2023]
Abstract
A color center in c-BN which is isoelectronic to diamond NV⁻ is predicted based on first-principles electronic structure calculations using the Heyd-Scuseria-Ernzerhof hybrid functional. The defect consists of a substitutional oxygen and an adjacent boron vacancy (O(N)-V(B)). We find that the O(N)-V(B) center is optically accessible with a zero-phonon line of about 1.6 eV. The O(N)-V(B) center also shares much of the characteristics of the GC-2 center often observed in c-BN. A prominent vibronic coupling peak is predicted to be around 55 meV, which is in excellent agreement with the characteristic phonon frequency (56 meV) observed in the luminescence spectra of the GC-2 center.
Collapse
|
36
|
Carbon kagome lattice and orbital-frustration-induced metal-insulator transition for optoelectronics. PHYSICAL REVIEW LETTERS 2014; 113:085501. [PMID: 25192104 DOI: 10.1103/physrevlett.113.085501] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Indexed: 06/03/2023]
Abstract
A three-dimensional elemental carbon kagome lattice, made of only fourfold-coordinated carbon atoms, is proposed based on first-principles calculations. Despite the existence of 60° bond angles in the triangle rings, widely perceived to be energetically unfavorable, the carbon kagome lattice is found to display exceptional stability comparable to that of C(60). The system allows us to study the effects of triangular frustration on the electronic properties of realistic solids, and it demonstrates a metal-insulator transition from that of graphene to a direct gap semiconductor in the visible blue region. By minimizing s-p orbital hybridization, which is an intrinsic property of carbon, not only the band edge states become nearly purely frustrated p states, but also the band structure is qualitatively different from any known bulk elemental semiconductors. For example, the optical properties are similar to those of direct-gap semiconductors GaN and ZnO, whereas the effective masses are comparable to or smaller than those of Si.
Collapse
|
37
|
Bortezomib inhibits C2C12 growth by inducing cell cycle arrest and apoptosis. Biochem Biophys Res Commun 2014; 445:375-80. [PMID: 24525132 DOI: 10.1016/j.bbrc.2014.02.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Accepted: 02/04/2014] [Indexed: 10/25/2022]
Abstract
Proteosome inhibitors such as bortezomib (BTZ) have been used to treat muscle wasting in animal models. However, direct effect of BTZ on skeletal muscle cells has not been reported. In the present study, our data showed that C2C12 cells exhibited a dose-dependent decrease in cell viability in response to increasing concentrations of BTZ. Consistent with the results of cell viability, Annexin V/PI analysis showed a significant increase in apoptosis after exposing the cells to BTZ for 24h. The detection of cleaved caspase-3 further confirmed apoptosis. The apoptosis induced by BTZ was associated with reduced expression of p-ERK. Cell cycle analysis revealed that C2C12 cells underwent G2/M cell cycle arrest when incubated with BTZ for 24h. Furthermore, BTZ inhibited formation of multinucleated myotubes. The inhibition of myotube formation was accompanied by decreased expression of Myogenin. Our data suggest that BTZ induces cell death and inhibits differentiation of C2C12 cells at clinically relevant doses.
Collapse
|
38
|
High-harmonic probing of electronic coherence in dynamically aligned molecules. PHYSICAL REVIEW LETTERS 2013; 111:243005. [PMID: 24483654 DOI: 10.1103/physrevlett.111.243005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Indexed: 05/12/2023]
Abstract
We introduce and demonstrate a new approach to measuring coherent electron wave packets using high-harmonic spectroscopy. By preparing a molecule in a coherent superposition of electronic states, we show that electronic coherence opens previously unobserved high-harmonic-generation channels that connect distinct but coherently related electronic states. Performing the measurements in dynamically aligned nitric oxide molecules we observe the complex temporal evolution of the electronic coherence under coupling to nuclear motion. Choosing a weakly allowed transition to prepare the wave packet, we demonstrate an unprecedented sensitivity that arises from optical interference between coherent and incoherent pathways. This mechanism converts a 0.1% excitation fraction into a ∼20% signal modulation.
Collapse
|
39
|
Magnetic topology changes induced by lower hybrid waves and their profound effect on edge-localized modes in the EAST tokamak. PHYSICAL REVIEW LETTERS 2013; 110:235002. [PMID: 25167503 DOI: 10.1103/physrevlett.110.235002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Indexed: 06/03/2023]
Abstract
Strong mitigation of edge-localized modes has been observed on Experimental Advanced Superconducting Tokamak, when lower hybrid waves (LHWs) are applied to H-mode plasmas with ion cyclotron resonant heating. This has been demonstrated to be due to the formation of helical current filaments flowing along field lines in the scrape-off layer induced by LHW. This leads to the splitting of the outer divertor strike points during LHWs similar to previous observations with resonant magnetic perturbations. The change in the magnetic topology has been qualitatively modeled by considering helical current filaments in a field-line-tracing code.
Collapse
|
40
|
Compensation in Al-doped ZnO by Al-related acceptor complexes: synchrotron x-ray absorption spectroscopy and theory. PHYSICAL REVIEW LETTERS 2013; 110:055502. [PMID: 23414033 DOI: 10.1103/physrevlett.110.055502] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Indexed: 06/01/2023]
Abstract
The synchrotron x-ray absorption near edge structures (XANES) technique was used in conjunction with first-principles calculations to characterize Al-doped ZnO films. Standard characterizations revealed that the amount of carrier concentration and mobility depend on the growth conditions, i.e. H(2) (or O(2))/Ar gas ratio and Al concentration. First-principles calculations showed that Al energetically prefers to substitute on the Zn site, forming a donor Al(Zn), over being an interstitial (Al(i)). The measured Al K-edge XANES spectra are in good agreement with the simulated spectra of Al(Zn), indicating that the majority of Al atoms are substituting for Zn. The reduction in carrier concentration or mobility in some samples can be attributed to the Al(Zn)-V(Zn) and 2Al(Zn)-V(Zn) complex formations that have similar XANES features. In addition, XANES of some samples showed additional features that are the indication of some α-Al(2)O(3) or nAl(Zn)-O(i) formation, explaining their poorer conductivity.
Collapse
|
41
|
Dirac fermions in strongly bound graphene systems. PHYSICAL REVIEW LETTERS 2012; 109:206802. [PMID: 23215516 DOI: 10.1103/physrevlett.109.206802] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Indexed: 06/01/2023]
Abstract
It is highly desirable to integrate graphene into existing semiconductor technology, where the combined system is thermodynamically stable yet maintain a Dirac cone at the Fermi level. First-principles calculations reveal that a certain transition metal (TM) intercalated graphene/SiC(0001), such as the strongly bound graphene on SiC with Mn intercalation, could be such a system. Different from freestanding graphene, the hybridization between graphene and Mn/SiC leads to the formation of a dispersive Dirac cone of primarily TM d characters. The corresponding Dirac spectrum is still isotropic, and the transport behavior is nearly identical to that of freestanding graphene for a bias as large as 0.6 V, except that the Fermi velocity is half that of graphene. A simple model Hamiltonian is developed to qualitatively account for the physics of the transfer of the Dirac cone from a dispersive system (e.g., graphene) to an originally nondispersive system (e.g., TM).
Collapse
|
42
|
Involvement of nuclear factor κB (NF-κB) in the downregulation of cyclooxygenase-2 (COX-2) by genistein in gastric cancer cells. J Int Med Res 2012; 39:2141-50. [PMID: 22289529 DOI: 10.1177/147323001103900610] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Genistein induces growth inhibition in various human cancer cell lines but its mechanism of action remains unknown. This study determined whether the effect of genistein is mediated via suppression of cyclo-oxygenase (COX)-2 protein, and elucidated the mechanism of action of this effect in the human gastric cancer cell line BGC-823. Genistein treatment inhibited cell proliferation and induced apoptosis in a dose- and time-dependent manner; Western blotting analysis indicated a significant dose-dependent decrease in COX-2 protein levels. Genistein treatment exerted a significant inhibitory effect on activation of the transcription factor nuclear factor κB (NF-κB). Additionally, the NF-κB inhibitor pyrrolidine dithiocarbamate caused a reduction in COX-2 protein levels and NF-κB activation, similar to the effect of genistein. Suppression of COX-2 protein may be important for the antiproliferative and proapoptotic effects of genistein in BGC-823 cells, and these effects may be partly mediated through the NF-κB pathway.
Collapse
|
43
|
1.86 W cw single-frequency 1319 nm ring laser pumped at 885 nm. APPLIED OPTICS 2012; 51:1241-1244. [PMID: 22441467 DOI: 10.1364/ao.51.001241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 01/11/2012] [Indexed: 05/31/2023]
Abstract
A 1.86 W cw single-frequency 1319 nm laser was produced by using an 885 nm-pumped Nd:YAG crystal with a compact four-mirror ring cavity, for the first time to our knowledge. The Nd:YAG produced a slope efficiency of 21% and an optical-to-optical efficiency of 18% with respect to the absorbed diode pump power. A near-diffraction-limited beam with M(2)=1.2 was achieved under the maximum output power.
Collapse
|
44
|
Comparison of anomalous Doppler resonance effects with molybdenum and graphite limiters on HT-7. PHYSICS OF PLASMAS 2012; 19:32509-325094. [PMID: 22509090 PMCID: PMC3326060 DOI: 10.1063/1.3695093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 02/29/2012] [Indexed: 05/31/2023]
Abstract
The material of limiter in HT-7 tokamak was changed from graphite to molybdenum in the last experimental campaign. The pitch angle scattering of runaway electrons due to anomalous Doppler resonance effects was observed. The experimental results agree very well with the stable boundary condition expected from the linear resistive theory but only agree with that from the nonlinear evolutionary of runaway-electron distribution theory in low electric field region. The current carried by runaway electrons is the same under different limiter conditions.
Collapse
|
45
|
Fermi-level tuning of epitaxial Sb2Te3 thin films on graphene by regulating intrinsic defects and substrate transfer doping. PHYSICAL REVIEW LETTERS 2012; 108:066809. [PMID: 22401108 DOI: 10.1103/physrevlett.108.066809] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Indexed: 05/31/2023]
Abstract
High-quality Sb2Te3 films are obtained by molecular beam epitaxy on a graphene substrate and investigated by in situ scanning tunneling microscopy and spectroscopy. Intrinsic defects responsible for the natural p-type conductivity of Sb2Te3 are identified to be the Sb vacancies and Sb(Te) antisites in agreement with first-principles calculations. By minimizing defect densities, coupled with a transfer doping by the graphene substrate, the Fermi level of Sb2Te3 thin films can be tuned over the entire range of the bulk band gap. This establishes the necessary condition to explore topological insulator behaviors near the Dirac point.
Collapse
|
46
|
Dynamic Jahn-Teller effect in the NV(-) center in diamond. PHYSICAL REVIEW LETTERS 2011; 107:146403. [PMID: 22107219 DOI: 10.1103/physrevlett.107.146403] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Indexed: 05/31/2023]
Abstract
The negatively charged nitrogen-vacancy (NV(-)) center in diamond is considered to be one of the most promising solid state systems for quantum information applications. Excited states of the NV(-) center play a center role in the proposed applications. Using a combination of first-principles calculations and vibronic interaction model analysis, we establish the presence of a dynamic Jahn-Teller effect in the (3)E excited state. The calculated temperature-dependent dephasing rate for the zero phonon line as well as the splitting of the first two vibronic states are in good agreement with experiment.
Collapse
|
47
|
Limits on passivating defects in semiconductors: the case of Si edge dislocations. PHYSICAL REVIEW LETTERS 2011; 107:035503. [PMID: 21838376 DOI: 10.1103/physrevlett.107.035503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Indexed: 05/31/2023]
Abstract
By minimizing the free energy while constraining dopant density, we derive a universal curve that relates the formation energy (E(form)) of doping and the efficiency of defect passivation in terms of segregation of dopants at defect sites. The universal curve takes the simple form of a Fermi-Dirac distribution. Our imposed constraint defines a chemical potential that assumes the role of "Fermi energy," which sets the thermodynamic limit on the E(form) required to overcome the effect of entropy such that dopant segregation at defects in semiconductors can occur. Using Si edge dislocation as an example, we show by first-principles calculations how to map the experimentally measurable passivation efficiency to our calculated E(form) by using the universal curve for typical n- and p-type substitutional dopants. We show that n-type dopants are ineffective. Among p-type dopants, B can satisfy the thermodynamic limit while improving electronic properties.
Collapse
|
48
|
Role of electronic excitation in the amorphization of Ge-Sb-Te alloys. PHYSICAL REVIEW LETTERS 2011; 107:015501. [PMID: 21797549 DOI: 10.1103/physrevlett.107.015501] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Indexed: 05/31/2023]
Abstract
First-principles molecular dynamics simulation reveals the effects of electronic excitation in the amorphization of Ge-Sb-Te. The excitation makes the phase change an element-selective process, lowers the critical amorphization temperature considerably, for example, to below 700 K at a 9% excitation, and reduces the atomic diffusion coefficient with respect to that of melt by at least 1 order of magnitude. Noticeably, the resulting structure has fewer wrong bonds and significantly increased phase-change reversibility. Our results point to a new direction in manipulating ultrafast phase-change processes with improved controllability.
Collapse
|
49
|
New structural picture of the Ge2Sb2Te5 phase-change alloy. PHYSICAL REVIEW LETTERS 2011; 106:025501. [PMID: 21405239 DOI: 10.1103/physrevlett.106.025501] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Indexed: 05/30/2023]
Abstract
Using electron microscopy and diffraction techniques, as well as first-principles calculations, we demonstrate that as much as 35% of the total Ge atoms in the cubic phase of Ge2Sb2Te5 locate in tetrahedral environments. The Ge-vacancy interactions play a crucial stabilizing role, leading to Ge-vacancy pairs and the sharing of vacancies that clusters tetrahedral Ge into domains. The Ge2Sb2Te5 structure with coexisting octahedral and tetrahedral Ge produces optical and structural properties in good agreement with experimental data and explains the property contrast as well as the rapid transformation in this phase-change alloy.
Collapse
|
50
|
Morphology and texture evolution of nanostructured CaF2 films on amorphous substrates under oblique incidence flux. NANOTECHNOLOGY 2010; 21:445701. [PMID: 20921590 DOI: 10.1088/0957-4484/21/44/445701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The morphology and biaxial texture of vacuum evaporated CaF(2) films on amorphous substrates as a function of vapour incident angle, substrate temperature and film thickness were investigated by scanning electron microscopy, x-ray pole figure and reflection high energy electron diffraction surface pole figure analyses. Results show that an anomalous [220] out-of-plane texture was preferred in CaF(2) films deposited on Si substrates at < 200 °C with normal vapour incidence. With an increase of the vapour incident angle, the out-of-plane orientation changed from [220] to [111] at a substrate temperature of 100 °C. In films deposited with normal vapour incidence, the out-of-plane orientation changed from [220] at 100 °C to [111] at 400 °C. In films deposited with an oblique vapour incidence at 100 °C, the texture changed from random at small thickness (5 nm) to biaxial at larger thickness (20 nm or more). Using first principles density functional theory calculation, it was shown that [220] texture formation is a consequence of energetically favourable adsorption of CaF(2) molecules onto the CaF(2)(110) facet.
Collapse
|