468 research outputs found
Properties of atomic intercalated carbon K4 crystals
The stability of atomic intercalated carbon crystals, XC (X=H,
Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ga, Ge, As, Se, Br, Rb
or Sr) is evaluated by geometry optimization and frozen phonon analysis based
on first principles calculations. Although C is unstable, NaC and
MgC are found to be stable. It is shown that NaC and MgC are
metallic and semi conducting, respectively
Automated Mapping of Ms 7.0 Jiuzhaigou Earthquake (China) Post-Disaster Landslides Based on High-Resolution UAV Imagery
The Ms 7.0 Jiuzhaigou earthquake that occurred on 8 August 2017 triggered hundreds of landslides in the Jiuzhaigou valley scenic and historic-interest area in Sichuan, China, causing heavy casualties and serious property losses. Quick and accurate mapping of post-disaster landslide distribution is of paramount importance for earthquake emergency rescue and the analysis of post-seismic landslides distribution characteristics. The automatic identification of landslides is mostly based on medium- and low-resolution satellite-borne optical remote-sensing imageries, and the high-accuracy interpretation of earthquake-triggered landslides still relies on time-consuming manual interpretation. This paper describes a methodology based on the use of 1 m high-resolution unmanned aerial vehicle (UAV) imagery acquired after the earthquake, and proposes a support vector machine (SVM) classification method combining the roads and villages mask from pre-seismic remote sensing imagery to accurately and automatically map the landslide inventory. Compared with the results of manual visual interpretation, the automatic recognition accuracy could reach 99.89%, and the Kappa coefficient was higher than 0.9, suggesting that the proposed method and 1 m high-resolution UAV imagery greatly improved the mapping accuracy of the landslide area. We also analyzed the spatial-distribution characteristics of earthquake-triggered landslides with the influenced factors of altitude, slope gradient, slope aspect, and the nearest faults, which provided important support for the further study of post-disaster landslide distribution characteristics, susceptibility prediction, and risk assessment.This work was funded by the National Key Research and Development Program of China (Project No. 2018YFC1505202), the National Natural Science Foundation of China (41941019), the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (SKLGP2020Z012), the project on identification and monitoring of potential geological hazards with remote sensing in Sichuan Province (510201202076888) and the Everest Scientific Project at Chengdu University of Technology (2020ZF114103)
Fermi Surface Evolution, Pseudo Gap and Stagger Gauge Field Fluctuation in Underdoped Cuprates
In the context of t-J model we show that in underdoped regime,beside the
usual long wave length gauge field fluctuation, an additional low energy
fluctuation, staggered gauge field fluctuation plays a crucial role in the
evolution of Fermi surface(FS) as well as the line shape of spectral function
for the cuprates. By including the staggered gauge field fluctuation we
calculate the spectral function of the electrons by RPA(random phase
approximation). The line shape of the spectral function near is very
broad in underdoped case and is quite sharp in overdoped case. For the spectral
function near , the quasiparticle peaks are always very sharp
in both underdoped and overdoped case. The temperature dependence of the
spectral function is also discussed in our present calculation. These results
fit well with the recent ARPES experiments. We also calculate the FS crossover
from a small four segment like FS to a large continuous FS. The reason of such
kind of FS crossover is ascribed to the staggered gauge field fluctuation which
is strong in underdoped regime and becomes much weaker in overdoped regime. The
pseudo gap extracted from the ARPES data can be also interpreted by the
calculation.Comment: 4 pages,6 eps figures include
Long-term outcomes of anatomic vs. non-anatomic resection in intrahepatic cholangiocarcinoma with hepatolithiasis: A multicenter retrospective study
BackgroundThe benefits of anatomic resection (AR) vs. non-anatomic resection (NAR) in patients with primary intrahepatic cholangiocarcinoma (ICC) with hepatolithiasis (HICC) are unclear. This study aimed to compare the long-term outcomes of AR vs. NAR in patients with HICC.MethodsA total of 147 consecutive patients with HICC who underwent R0 hepatectomy were included. Overall survival (OS) and recurrence-free survival (RFS) following AR vs. NARs were compared using a 1:1 propensity score matching (PSM) analysis. A subgroup analysis was also conducted according to whether there are lymph node metastases (LNM).ResultsIn a multivariate analysis, CA 19-9 (>39 U/L), microvascular invasion, LNM, and NAR were independent risk factors for poor RFS and OS rates, whereas multiple tumors were independent risk factors for OS. AR had better 1-, 3-, and 5-year RFS and OS rates than NAR (OS: 78.7, 58.9, and 28.5%, respectively, vs. 61.2, 25.4, and 8.8%, respectively; RFS: 59.5, 36.5, and 20.5%, respectively, vs. 38.2, 12.1, and 6.9%, respectively). After PSM, 100 patients were enrolled. The NAR group also had significantly poorer OS and RFS (OS: 0.016; RFS: p = 0.010) than the AR group. The subgroup analysis demonstrated that in HICC without LNM, OS and RFS were significantly poorer in the NAR group than the AR group, while no significant differences were observed in HICC with LNM before or after PSM.ConclusionAnatomic resection was associated with better long-term survival outcomes than NAR in patients with HICC, except for patients with LNM
Effects of different starch sources on Bacillus spp. in intestinal tract and expression of intestinal development related genes of weanling piglets
The study was conducted to evaluate the effects of different starch sources on Bacillus spp. in intestinal tract and expression of intestinal development related genes of weanling piglets. Twenty-eight PIC male piglets were divided into four homogeneous groups according to initial body weight (similar birth and parity, weaned at 21Ā Ā±Ā 1.5Ā days). Diets for the four treatments consisted of corn starch, wheat starch, tapioca starch and pea starch with the determined ratio for amylose to amylopectin of 0.21, 0.24, 0.12 and 0.52 respectively. Real-time quantitative polymerase chain reaction was applied to: (1) detect genomic DNA of Bacillus and to quantify the number of Bacillus in the intestinal tract chyme of piglets with the primers and probe which designed based on the 16S rRNA sequences of maximum species of Bacillus on GenBank; (2) measure the mRNA level of glucagon-like peptide 2 (GLP-2), insulin-like growth factors 1 (IGF-1) and epidermal growth factor (EGF) in duodenum, jejunum and ileum. Results showed that the number of Baciilus and the percentage based on all bacteria in the whole intestinal content of piglets fed pea starch was highest in all groups (PĀ <Ā 0.05). There was no significant differance on copy numbers for all bacteria and Bacillus in the whole intestinal tract of piglets between the corn starch group and wheat starch group (PĀ >Ā 0.05). In addition, the expression level of GLP-2, IGF-1 mRNA in jejunum and ileum of pea starch treatment (the high amylose/amylopectin ratio) were increased while the tapioca starch decreased their mRNA level significantly compared to other three treatments (PĀ <Ā 0.05). There was no significant difference for the mRNA level of EGF in each group. The present study revealed that high amylose/amylopectin ratio of starches significantly enhanced the numbers of Bacillus in all segments of intestine and the mRNA level of intestinal development related genes
Identifying the pollution characteristics of atmospheric polycyclic aromatic hydrocarbons associated with functional districts in Ningbo, China
Duplicate polyurethane foam based passive air samplers (PUF-PAS) were deployed at seven sites in Ningbo from November 1, 2014 to October 31, 2015 and were used to analyze 15 priority polycyclic aromatic hydrocarbons (PAHs). Higher benzo[a]pyrene toxic equivalent concentrations were observed in the industrial areas during wintertime. Correspondence analysis (CA) was used to characterize the PAH congener profiles associated with each functional district and their temporal variations. It showed that different PAH composition profiles and seasonal variations were observed in mountain, rural area and residential areas; and different industrial layouts also led to different properties of PAH congener emissions. Higher levels of PAHs were observed around oil refinery in summer and at mountainous areas in winter, which might be attributed to the evaporation of petroleum and the impact of local biomass burning. This study also demonstrated that the factors influencing the representativeness of a site could be more clearly understood using PUF-PAS and CA analysis. Ā© 2019, Springer Science+Business Media, LLC, part of Springer Nature
No significant enrichment of rare functionally defective CPA1 variants in a large Chinese idiopathic chronic pancreatitis cohort
Rare functionally defective carboxypeptidase A1 (CPA1) variants have been reported to predispose
to nonalcoholic chronic pancreatitis, mainly the idiopathic subtype. However, independent replication has so far been lacking, particularly in Asian cohorts where initial studies employed small sample sizes. Herein we performed targeted next-generation sequencing of the CPA1 gene
in 1,112 Han Chinese idiopathic chronic pancreatitis (ICP) patientsāthe largest ICP cohort so far analyzed in a single populationāand 1,580 controls. Sanger sequencing was used to validate called variants, and theCPA1 activity and secretion of all newly found variants were measured.Atotal of 18 rare CPA1 variants were characterized, 11 of which have not been previously described. However,no significant association was noted with ICP irrespective of whether all rare variants [20 out of 1,112 (1.8%) in patients vs. 24 out of 1,580 (1.52%) in controls; P = 0.57] or functionally
impaired variants [three out of 1,112 (0.27%) in patients vs. two out of 1,580 (0.13%) in controls; P = 0.68] were considered
Parkinson's disease constipation effect of electroacupuncture at ST25 through colonic motility and enteric neuropathology
BackgroundThe enteric nervous system (ENS) plays a central role in developing Parkinson's disease (PD) constipation, and the regulation of the ENS may be a key component in treating PD constipation. Electroacupuncture (EA) can effectively treat constipation symptoms in PD, but research on its specific mechanisms, especially in terms of ENS, is relatively lacking. Therefore, we investigated whether EA at ST25 promotes the restoration of ENS structure and colonic motor function in the rotenone-induced PD constipation rat model.MethodsIn this study, we evaluated constipation symptoms by stool characteristics, excretion and water volume, and whole gut transit time and observed colonic motility regulation through colonic motion detection and pathological changes in the colonic myenteric nervous plexus by transmission electron microscopy and immunofluorescence staining.ResultsEA significantly improved the constipation symptoms and positively adjusted the colonic motility in rotenone-induced PD constipation rats. At the same time, EA reversed the rotenone-induced colonic myenteric nervous plexus injury and regulated the ratio of inhibitory and excitatory neurotransmitters.ConclusionOur results indicate that EA treatment of PD constipation may be mediated through the adjustment of ENS
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