204 research outputs found
The application of geochemical methods in earthquake prediction in China
Several geochemical anomalies were observed before the Haichen, Longling, Tangshan, and Songpan earthquakes and their strong aftershocks. They included changes in groundwater radon levels; chemical composition of the groundwater (concentration of Ca^(++), Mg^(++), Cl^−, SO_4= and HCO_3− ions); conductivity; and dissolved gases such as H_2, CO_2, etc. In addition, anomalous changes in water color and quality were observed before these large earthquakes. Before some events gases escaped from the surface, and there were reports of "ground odors" being smelled by local residents. The large amount of radon data can be grouped into long‐term and short‐term anomalies. The long‐term anomalies have a radon emission build up time of from a few months to more than a year. The short‐term anomalies have durations from a few hours or less to a few months
Composition and Morphology of Nanocrystals in Urines of Lithogenic Patients and Healthy Persons
The composition and morphology of nanocrystals in urines of healthy persons and lithogenic patients were comparatively investigated by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was shown that the main composition of urinary nanocrystals in healthy persons were calcium oxalate dihydrate (COD), uric acid, and ammonium magnesium phosphate (struvite). However, the main compositions of urinary nanocrystals in lithogenic patients were struvite, β-tricalcium phosphate, uric acid, COD, and calcium oxalate monohydrate (COM). According to the XRD data, the size of nanocrystals was calculated to be 23∼72 nm in healthy urine and 12∼118 nm in lithogenic urine by Scherer formula. TEM results showed that the nanocrystals in healthy urine were dispersive and uniform with a mean size of about 38 nm. In contrast, the nanocrystals in lithogenic urine were much aggregated with a mean size of about 55 nm. The results in this work indicated that the urinary stone formation may be prevented by diminishing the aggregation and the size differentiation of urinary nanocrystals by physical or chemical methods
Enhancement of polar phases in PVDF by forming PVDF/SiC nanowire composite
Different contents of silicon carbide (SiC) nanowires were mixed with Poly(vinylidene fluoride) (PVDF) to facilitate the polar phase crystallization. It was shown that the annealing temperature and SiC content affected on the phase and crystalline structures of PVDF/SiC samples. Furthermore, the addition of SiC nanowire enhanced the transformation of non-polar α phase to polar phases and increased the relative fraction of β phase in PVDF. Due to the nucleating agent mechanism of SiC nanowires, the ion-dipole interaction between the negatively charged surface of SiC nanowires and the positive CH2 groups in PVDF facilitated the formation of polar phases in PVDF
A Scoring Model Based on Neutrophil to Lymphocyte Ratio Predicts Recurrence of HBV-Associated Hepatocellular Carcinoma after Liver Transplantation
Neutrophil to lymphocyte ratio (NLR) has been proposed to predict prognosis of hepatocellular carcinoma (HCC). However, the cut-off values are empirical. We determined the optimal cut-off value to predict HCC recurrence after liver transplantation (LT) and further established a scoring model based on NLR.<0.001). Univariate analysis revealed that tumor size >5 cm, tumor number >3, macrovascular invasion, AFP≥400 µg/L, NLR≥3, and HBV-DNA level >5 log10 copies/mL were preoperative predictors of DFS. Cox regression analysis showed macrovascular invasion, tumor number, and high NLR were independent prognostic factors. We then established a preoperative prognostic score based on multivariate analysis. Each factor was given a score of 1. Area under the ROC curve of the score was 0.781. All nine patients with score 3 developed recurrence within 6 months after LT. Of 71 patients without vascular invasion, three patients with both tumor number >3 and NLR≥3 developed recurrence within 14 months after LT while the 5-year DFS and OS for patients with a score of 0 or 1 were 68.1% and 62.8%, respectively.Preoperative elevated NLR significantly increases the risk of recurrence in patients underwent LT for HCC. Patients with both NLR≥3 and tumor number >3 are not a good indication for LT. Our score model may aid in the selection of patients that would most benefit from transplantation for HCC
4-[5-(4-Pyridyl)-1,3,4-oxadiazol-2-yl]pyridine N-oxide–isophthalic acid (1/1)
The title compound, C12H8N4O2·C8H6O4, was synthesized from 4-[5-(4-pyridyl)-1,3,4-oxadiazol-2-yl]pyridine N-oxide and isophthalic acid. The two molecules are linked through O—H⋯O and O—H⋯N hydrogen bonds. Weak intramolecular π–π interactions between the two hydrogen-bonded chains result in the formation a one-dimensional supramolecular curved tape (the face-to-face distance between the pyridine N-oxide ring and the benzene ring is 3.7 Å)
Time-Specific Ecologic Niche Models Forecast the Risk of Hemorrhagic Fever with Renal Syndrome in Dongting Lake District, China, 2005–2010
Background: Hemorrhagic fever with renal syndrome (HFRS), a rodent-borne infectious disease, is one of the most serious public health threats in China. Increasing our understanding of the spatial and temporal patterns of HFRS infections could guide local prevention and control strategies.
Methodology/Principal Findings: We employed statistical models to analyze HFRS case data together with environmental data from the Dongting Lake district during 2005–2010. Specifically, time-specific ecologic niche models (ENMs) were used to quantify and identify risk factors associated with HFRS transmission as well as forecast seasonal variation in risk across geographic areas.
Results showed that the Maximum Entropy model provided the best predictive ability (AUC = 0.755). Time-specific Maximum Entropy models showed that the potential risk areas of HFRS significantly varied across seasons. High-risk areas were mainly found in the southeastern and southwestern areas of the Dongting Lake district. Our findings based on models focused on the spring and winter seasons showed particularly good performance. The potential risk areas were smaller in March, May and August compared with those identified for June, July and October to December. Both normalized difference vegetation index (NDVI) and land use types were found to be the dominant risk factors.
Conclusions/Significance: Our findings indicate that time-specific ENMs provide a useful tool to forecast the spatial and temporal risk of HFRS
Pain, obesity, adenosine salvage disruption, and smoking behavior mediate the effect of gut microbiota on sleep disorders: results from network Mendelian randomization and 16S rDNA sequencing
ObjectivesThe objective of this study is to investigate the indirect causalities between gut microbiota and sleep disorders.MethodsIn stage 1, we utilized 196 gut microbiota as the exposure factor and conducted a two-sample univariable Mendelian randomization (MR) analysis on five sleep disorders: insomnia, excessive daytime sleepiness (EDS), sleep-wake rhythm disorders (SWRD), obstructive sleep apnea (OSA), and isolated REM sleep behavior disorder (iRBD). In stage 2, we validated the MR findings by comparing fecal microbiota abundance between patients and healthy controls through 16S rDNA sequencing. In stage 3, we explored the indirect pathways by which the microbiota affects sleep, using 205 gut microbiota metabolic pathways and 9 common risk factors for sleep disorders as candidate mediators in a network MR analysis.ResultsIn stage 1, the univariable MR analysis identified 14 microbiota potentially influencing five different sleep disorders. In stage 2, the results from our observational study validated four of these associations. In stage 3, the network MR analysis revealed that the Negativicutes class and Selenomonadales order might worsen insomnia by increasing pain [mediation: 12.43% (95% CI: 0.47, 24.39%)]. Oxalobacter could raise EDS by disrupting adenosine reuptake [25.39% (1.84, 48.95%)]. Allisonella may elevate OSA risk via obesity promotion [36.88% (17.23, 56.54%)], while the Eubacterium xylanophilum group may lower OSA risk by decreasing smoking behavior [7.70% (0.66, 14.74%)].ConclusionTriangulation of evidence from the MR and observational study revealed indirect causal relationships between the microbiota and sleep disorders, offering fresh perspectives on how gut microbiota modulate sleep
Correlated radon and CO_2 variations near the San Andreas Fault
Correlations have been observed between groundwater radon and thoron concentrations and carbon dioxide discharges at the Lake Hughes station of the Caltech radon monitoring network. The Lake Hughes site is one of three radon monitoring stations located near the "big bend" segment of the San Andreas fault which began to record anomalous radon levels in August 1981. Two stations, Lake Hughes and Lytle Creek, recorded anomalous increases in radon while the third, Sky Forest, recorded an anomalous decrease. Several weeks after the onset of the anomaly, strongly correlated radon fluctuations began at Lake Hughes and Lytle Creek. These radon spikes also were found to be phase anti-correlated with barometric pressure fluctuations. Analyses of gas grab samples showed relatively high levels of CO_2 and ethylene in borehole air at Lake Hughes and Lytle Creek, while analyses of water samples showed relatively large increases in HCO_3^− at both sites. Isotopic analysis of one gas sample from Lake Hughes yielded a ^(13)C δ value of −22 ‰, which suggests that the CO_2 originates from the oxidation of organic material. The correlation in radon fluctuations at Lake Hughes and Lytle Creek and their common dependence on barometric pressure changes began shortly after the onset of the radon anomaly in August, and probably resulted from the simultaneous saturation of the water in these boreholes with carbon dioxide
Altered cognition and anxiety in adolescent offspring whose mothers underwent different-pattern maternal sleep deprivation, and cognition link to hippocampal expressions of Bdnf and Syt-1
BackgroundInadequate sleep during pregnancy negatively affects the neural development of offspring. Previous studies have focused on the continuous sleep deprivation (CSD) paradigm, but the sleep pattern during late pregnancy is usually fragmented.ObjectiveTo compare the effects of CSD and fragmented sleep deprivation (FSD) in late pregnancy on emotion, cognition, and expression of synaptic plasticity-related proteins in offspring mice.MethodsPregnant CD-1 mice were either subjected to 3/6 h of CSD/FSD during gestation days 15–21, while those in the control group were left untreated. After delivery, the offspring were divided into five groups, i.e., control (CON), short or long CSD (CSD3h, CSD6h), and short or long FSD (FSD3h, FSD6h). When the offspring were 2 months old, the anxiety-like behavior level was tested using the open field (OF) and elevated plus maze (EPM) test, and spatial learning and memory were evaluated using the Morris water maze (MWM) test. The expression of hippocampal of brain-derived neurotrophic factor (Bdnf) and synaptotagmin-1 (Syt-1) was determined using RT-PCR and western blotting.ResultsThe CSD6h, FSD3h, and FSD6h had longer latency, fewer center times in the OF test, less open arms time and fewer numbers of entries in the open arms of the EPM, longer learning distance swam and lower memory percentage of distance swam in the target quadrant in the MWM test, and decreased BDNF and increased Syt-1 mRNA and protein levels in the hippocampus. Compared to the CSD6h, the FSD3h and FSD6h had longer distance swam, a lower percentage of distance swam in the target quadrant, decreased BDNF, and increased Syt-1 mRNA and protein levels in the hippocampus.ConclusionThe results suggested that maternal sleep deprivation during late pregnancy impairs emotion and cognition in offspring, and FSD worsened the cognitive performance to a higher extent than CSD. The observed cognitive impairment could be associated with the expression of altered hippocampal of Bdnf and Syt-1 genes
An overlooked nitrogen loss linked to anaerobic ammonium oxidation in estuarine sediments in China
Purpose Despite its importance, anammox (anaerobic ammonium oxidation) in estuarine sediment systems remains poorly understood, particularly at the continental scale. This study aimed to understand the abundance, diversity, and activity of anammox bacteria and to determine the main factors influencing the anammox process in estuarine sediments in China. Materials and methods Estuarine sediments were collected from 18 estuaries spanning over 4000 km. Experiments using an 15N–tracer, quantitative PCR, and clone library construction were used to determine the activity, abundance, and diversity of anammox bacteria. The impact of environmental factors on anammox processes was also determined
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