Insights into the cause of the Oroville dam spillway failure, 2017, California.

Earth internal seepage erosion in weathered bedrock under infrequently used hydraulic structures is often overlooked, which causes some solid particles to break away from the solid skeleton, degrading the earth's strength, and even causing unanticipated hydraulic engineering failures. The flood on the Oroville dam spillway in California in 2017 was caused by disturbed water flow due to a crack in the spillway chute caused by internal erosion in poorly weathered bedrock. The abnormal water flow of the spillway in the early stage and subsequent investigation revealed that the main reason for the accident was the insufficient weathered bedrock under the spillway chute. In this study, we formulated a coupled hydro-mechanical mechanism for internal erosion in weathered bedrock during the early stages. Using this model, we conducted an internal erosion numerical simulation at early stage, and the results showed that the physical characteristics of the weathered bedrock were degraded. Our results show the coupling analysis of quantitative computation during the early stage of internal erosion in weathered bedrock, which can provide an early warning method for the occurrence of internal erosion to avoid hydraulic disasters.

Metal chalcogenide nanorings for temperature-strain dual-mode sensing.

Most metal chalcogenides exhibit layered structures and anisotropic morphologies such as nanosheets, nanoplates, and nanotubes, as well as nanosheet-assembled nanoflowers. Unconventional morphologies such as nanorings may bring appealing properties to functional materials, but they have not been realized with metal chalcogenides. Herein, we report that Sn0.2Mo0.8S2 nanorings with a mixed 1T/2H phase were synthesized by etching SnS2 cores from Sn1-xMoxS2/SnS2 lateral heterostructures. Flexible electronic sensors based on these Sn0.2Mo0.8S2 nanorings exhibited excellent temperature and strain sensing performance, with a negative temperature coefficient of resistance of -0.013 °C-1 and a minimum detectable strain of 0.09%. In addition, the dual-functional flexible electronic sensors with easy fabrication and good wearability showed great promise for tracking human activities and monitoring inapparent health-related signals.

The Determination Method of Total Polyphenol in Tea and Substitute Tea Based on [Ag(HIO6)2]5--Luminol Chemiluminescence System.

BACKGROUND: Scientific, accurate, and rapid detection of the composition and content of tea polyphenols is an important basis for their rational use and giving full play to their physiological effect. The spectrophotometric assays for total polyphenols have poor selectivity. Therefore, there is a need to develop a simple and reliable method for the determination of the total polyphenolic level in tea products. OBJECTIVE: The aim of this research was to develop a flow injection chemiluminescence (FI-CL) method based on the Ag(III)-luminol system for the total polyphenol content analysis of tea and substitute tea. METHOD: Through Box-Behnken experimental design, we selected the optimum determination condition. The Ag(III) concentration was 5 × 10-5 mol/L, and the luminol concentration was 3 × 10-7 mol/L (including 0.15 mol/L NaOH). The peristaltic pump is 25 r/min, and the photomultiplier voltage is 600 v. Sample extracts were diluted 100 000 times for the FI-CL assay. RESULTS: Under optimal conditions, CL intensities were proportional to total polyphenol content (in terms of gallic acid concentrations) in the range of 0.1∼100 µg/L. The LOD and LOQ were 0.03 µg/L and 0.1 µg/L. The recovery values were in the range of 86.3-111.0% with a RSD of 1.04∼2.62%. The polyphenolic content of 12 teas and 6 substitute teas was determined, and the results of the developed method and Folin-Ciocalteu method were highly correlated (r = 0.9493 for tea and r = 0.8533 for substitute tea). CONCLUSIONS: The proposed method is better than the Folin-Ciocalteu method in terms of selectivity, sensitivity, and accuracy. It is suitable for the determination of polyphenol content not only in tea, but also in substitute tea. HIGHLIGHTS: We developed a new flow-injection analysis method for polyphenolic content determination based on the Ag(III)-luminol chemiluminescence system. It is simple, rapid, sensitive, and accurate. It is suitable for the determination of polyphenols content not only in tea, but also in substitute tea.

High Interfacial-Energy and Lithiophilic Janus Interphase Enables Stable Lithium Metal Anodes.

The stability of solid electrolyte interphase (SEI) layers is critical for developing lithium (Li) metal batteries. However, the fabrication of stable SEI layers is plagued by un-controlled structures, properties, and functions. Here a controllable design of an ordered LiF-rich and lithiophilic hybrid Janus interphase (LiF-HJI) is reported using organic fluorination reagent as a functional SEI precursor. The LiF-HJI with a lower crystalline LiF layer and an upper Li organosulfide layer provides high interfacial energy with the Li metal and strong Li-ion affinity, allows homogenous Li-ion distribution, fast and uniform Li-ion transport, and excellent mechanical and passivation properties, enabling stable Li metal anodes under harsh conditions, such as high deposition capacities (6 mA h cm-2 ), current densities (10 mA cm-2 ), and rates (5 C). Stable LiF-HJI@Li greatly improves cycling stability and capacity retention (80.1% after 300 cycles) of Li||LiNi0.8 Co0.1 Mn0.1 O2 cells at a commercial-level areal capacity (≈4.2 mA h cm-2 ). Even under a lean-electrolyte condition of 3 g Ah-1 , 80% capacity retention can be maintained after 100 cycles, demonstrating excellent cycling performance under such harsh conditions.

Associations of long-term exposure to traffic-related air pollution with risk of valvular heart disease based on a cross-sectional study.

Emerging evidence demonstrated that traffic-related air pollution induced adverse effects on cardiovascular system. We designed a population-based cross-sectional study to explore the association between residential proximity to major roadways, traffic density and the prevalence of valvular heart disease (VHD). A total of 34040 subjects from a Rural Health Project between 2013 and 2018 were collected. According to the inclusion and exclusion criteria, 4158 participants were enrolled in the final analysis. And we calculated the subjects' proximity to major roadways and collected the traffic density on the major roadways. Transthoracic echocardiography (TTE) was performed to diagnose the VHD, according to the current AHA/ACC (the American Heart Association and the American College of Cardiology) guidelines. Differences between groups were examined by the one-way ANOVAs for continuous variables and the chi-square tests for categorical variables. A logistic regression models were used to assess the associations. The stratified analysis by age and sex were conducted to further analyze the association. The restricted cubic spline analysis was performed to further evaluate the association between road way distance and VHD. Bonferroni test was used to adjust the significance level. The subjects closer to the major roads had the higher risk of tricuspid regurgitation (TR) (odds risk, OR = 1.519, 95% confidence intervals, 95%CI: 1.058-2.181), especially in female. The risk of VHD was positive (high traffic density VS low traffic density, OR = 1.799, 95%CI: 1.221-2.651), especially in female. In addition, the high traffic density was associated with the risk of mitral regurgitation (MR) (OR = 1.758, 95%CI: 1.085-2.848). The restricted cubic spline analysis found a threshold distance of about 300 m, where had the lowest risk of VHD, aortic regurgitation (AR), MR, TR. Our results found a positive association between traffic-related air pollution and VHD especially in female.

Differences in regional distribution and inequality in health-resource allocation at hospital and primary health centre levels: a longitudinal study in Shanghai, China.

OBJECTIVES: To analyse differences in regional distribution and inequality in health-resource allocation at the hospital and primary health centre (PHC) levels in Shanghai over 7 years. DESIGN: A longitudinal survey using 2010-2016 data, which were collected for analysis. SETTING: The study was conducted at the hospital and PHC levels in Shanghai, China. OUTCOME MEASURES: Ten health-resource indicators were used to measure health-resource distribution at the hospital and PHC levels. In addition, the Theil Index was calculated to measure inequality in health-resource allocation. RESULTS: All quantities of healthcare resources per 1000 people in hospitals and PHCs increased across Shanghai districts from 2010 to 2016. Relative to suburban districts, the central districts had higher ratios, both in terms of doctors and equipment, and had faster growth in the doctor indicator and slower growth in the equipment indicator in hospitals and PHCs. The Theil Indices of all health-resource allocation in hospitals had higher values compared with those in PHCs every year from 2010 to 2016; furthermore, the Theil Indices of the indicators, except for technicians and doctors in hospitals, all exhibited downward time trends in hospitals and PHCs. CONCLUSIONS: Increased healthcare resources and reduced inequality of health-resource allocation in Shanghai during the 7 years indicated that measures taken by the Shanghai government to deepen the new round of healthcare reform in China since 2009 had been successful. Meanwhile there still existed regional difference between urban and rural areas and inequality across different medical institutions. To solve these problems, we prescribe increased wages, improved working conditions, and more open access to career development for doctors and nurses; reduced investments in redundant equipment in hospitals; and other incentives for balancing the health workforce between hospitals and PHCs.

Experimental and dynamical study of a dual Q-switched intracavity OPO based on few-layer MoSe2 SA.

A 2.5nm-thickness molybdenum diselenide (MoSe2) saturable absorber (SA) is prepared by electron beam evaporation (EBE) method. Applying the prepared MoSe2 SA to an acousto-optic (AO) Q-switched fundamental laser, a dual-loss-modulated intra-cavity optical parametric oscillator (IOPO) has been experimentally realized. The signal-pulse train from this IOPO has 0.0053 standard deviation (SD) of pulse amplitude. When the MoSe2 SA is applied to IOPO, the signal pulse is compressed by maximum 68%, the peak power increases by 274%, and the nonlinear conversion increases by 12.6%. To solve the established rate equation of IOPO, the ground-state and excited-state absorption cross section of MoSe2 are rationally estimated to be 1.04×10-18cm-2 and 6.25×10-19cm-2 from the measured transmittance curve, and the excited-state lifetime is 275.6µs. The numerical solution of the equations fits the experimental data well.

Fecal microbiota transplantation treatment for refractory ulcerative colitis with allergy to 5-aminosalicylic acid: A case report.

INTRODUCTION: Fecal microbiota transplantation (FMT) is currently being explored as a potential therapy for ulcerative colitis (UC). Here, we report the first case of a UC patient with allergy to 5-aminosalicylic acid (5-ASA) who underwent FMT and achieved clinical remission. CASE PRESENTATION: This patient had a 9-year history of UC and was allergic to 5-ASA. He suffered from gradually aggravated abdominal pain and frequent bloody diarrhea. There was a continuous distribution of superficial erosion and ulceration by colonoscopy. After steroid therapy failed, he underwent FMT. The donated fecal microbes were purified in laboratory and then transplanted into the terminal ileum and right colon of the patient by colonoscopy. During the 9 months' follow-up, FMT has proved its efficacy in inducing and maintaining clinical and endoscopic remission of the patient. CONCLUSION: The choice of treatment for refractory UC patients who are allergic to 5-ASA is relatively limited. In our case, we highlight the specific role of FMT for refractory UC with absence of 5-ASA through intestinal microbiota reconstruction.

Development of Chloroplast Microsatellite Markers and Analysis of Chloroplast Diversity in Chinese Jujube (Ziziphus jujuba Mill.) and Wild Jujube (Ziziphus acidojujuba Mill.).

Ziziphus is an important genus within the family Rhamnaceae. This genus includes several important fruit tree species that are widely planted in China and India, such as the Chinese jujube (Ziziphus jujuba Mill.), the wild jujube (Z. acidojujuba), and the Indian jujube (Z. mauritiana). However, information about their domestication based on the chlorotype diversity of Chinese jujube population is lacking. In this study, chloroplast microsatellite (cpSSR) markers were developed and used to investigate the genetic relationships between and domestication of jujube cultivars and wild jujube populations. Primer sets flanking each of the 46 cpSSR loci in non-coding regions of the chloroplast genome sequence of Z. jujuba Mill. cv. 'Junzao' were designed. In total, 10 markers showed polymorphisms from 15 samples (9 jujube cultivars and 6 wild jujube individuals), of which 8 loci were due to variations in the number of mononucleotide (A/T) repeats and 2 were due to indels. Six cpSSR markers were used in further analyses of 81 additional samples (63 jujube cultivars, 17 wild jujube samples, and 1 Indian jujube). Using these cpSSR markers, the number of alleles per locus ranged from two to four. In general, the Shannon Index (I) for each cpSSR ranged from 0.159 to 0.1747, and the diversity indices (h) and uh were 0.061 to 0.435 and 0.062 to 0.439, respectively. Seven chlorotypes were found; the Indian jujube showed distinct chlorotypes, and both the Chinese and wild jujube had four chlorotypes and shared two chlorotypes. A dominant chlorotype (G) accounted for 53 of 72 jujube cultivars and 13 of 23 wild jujube individuals. All chlorotypes were highly localized along the Yellow River, from the mid- to the lower reaches, suggesting a wide origin of jujube. These cpSSR markers can be applied to population and evolution studies of Chinese jujube and wild jujube.

A novel derivatization approach for determination of ketamine in urine and plasma by gas chromatography-mass spectrometry.

A new method was developed for determination of ketamine (KT) in urine and plasma samples by derivatization and gas chromatography-mass spectrometry. In this article, KT was first derivatized with sodium nitrite to volatile N-nitrosamines under acidic condition. Then the derivative had been identified by the mass spectra. The derivatization conditions including the amount of hydrochloric acid, the amount of sodium nitrite, reaction temperature, reaction time and the extraction reagents were optimized. Calibration curves were linear in the range of 0.04-20 µg mL(-1) for KT, and the limit of detection (LOD) and limit of quantitation (LOQ) were 0.01 µg mL(-1) and 0.04 µg mL(-1), respectively. The results of recovery indicated that the method had good precision and reproducibility. Compared with existing derivatization methods, this method provided a rapid, convenient, effective and low-cost way for gas chromatography method of KT quantification.

Preparation of a magnetic molecularly imprinted polymer with pseudo template for rapid simultaneous determination of cyromazine and melamine in bio-matrix samples.

A magnetic molecularly imprinted polymer (M-MIP) for cyromazine and melamine was prepared by simple suspension polymerization using a pseudo template, 2-(4,6-diamino-1,3,5-triazin-2-ylamino)ethanethiol disulfide. The M-MIP was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and vibrating sample magnetometry. Molecular recognition properties and binding capability to cyromazine and melamine were evaluated by adsorption testing, which showed the M-MIP had better affinity and selectivity than the magnetic non-imprinted polymer (M-NIP) for cyromazine and melamine. A method based on molecularly imprinted solid-phase extraction assisted by magnetic separation was developed for extraction of cyromazine and melamine from bio-matrix samples. Various conditions, for example desorption conditions, amount of M-MIP, extraction time, and sample pH were optimized. High-performance liquid chromatography with UV detection was used to determine cyromazine and melamine after extraction. The proposed method was successfully applied to determination of cyromazine and melamine in egg and milk samples. Recovery of standard spiked cyromazine and melamine from these samples was between 71.86 and 80.57%, with intraday and interday relative standard deviation ranging from 3.45 to 6.39% and from 3.95 to 7.84%, respectively. The results indicate that the pseudo template M-MIP can be used for preconcentration, purification, and analysis of cyromazine and melamine in bio-matrix samples.

The application of pseudo template molecularly imprinted polymer to the solid-phase extraction of cyromazine and its metabolic melamine from egg and milk.

The combination of molecularly imprinted polymer with high performance liquid chromatography has been developed to determine cyromazine and its metabolic melamine in some samples. However, the potential risk of template leakage used in molecularly imprinted polymer is a major disadvantage. To solve this problem, 2-(4,6-diamino-1,3,5-triazin-2-ylamino) ethanethiol disulfide, a molecule that shares the similar imprinting sites with cyromazine and melamine, was selected as pseudo template to prepare molecularly imprinted polymer. Methacrylic acid, ethylene glycol dimethyl acrylate and toluene were selected as functional monomer, crosslinker and porogen, respectively. The molecular recognition property and binding capability of cyromazine and melamine were evaluated by adsorption test and Scatchard analysis. The results showed that the molecularly imprinted polymer based on pseudo template had more excellent affinity and selectivity for cyromazine and melamine. The resulting molecularly imprinted polymer was used as a solid-phase extraction material to enrich cyromazine and melamine in egg and milk samples for high performance liquid chromatography analysis. The solid-phase extraction process was carefully optimized. It was found that when different concentration of cyromazine and melamine standards were spiked into samples, satisfactory recovery rate of cyromazine and melamine were obtained as 85.6-98.8% with relative standard deviation <5.5%.

[Analysis of lipid-soluble components of Amomum villosum fruits by GC/MS].

OBJECTIVE: To analyse the lipid-soluble components of Amomum villosum fruits by GC/MS. METHODS: Lipid-soluble components in pericarps and seeds of A. villosum were extracted by Soxhlet extraction. The Lipid-soluble components were esterified and then analyzed by gas chromatography-mass spectrometry (GC-MS). RESULTS: Twenty-five and thirteen compounds were identified in pericarps and seeds of A. villosum, respectively, mainly including fatty acids and their esters. CONCLUSION: The results indicate that it is highly potential and significant to exploit its value in foods, medicines and healthy care.

Determination of cortisol in human blood sera by a new Ag(III) complex-luminol chemiluminescent system.

A new chemiluminescence (CL) system based on the reaction of Ag(III) complex with luminol is, for the first time, reported in this work. Incorporated with a flow injection analyses (FIA), the new CL system has been applied for the determination of free cortisol in human sera. The system is based on the CL reaction of luminol with Ag(III) in alkaline solutions, while cortisol can dramatically enhance CL intensities. Under optimum conditions, CL intensities are proportional to concentration of cortisol in the range of 0.05-7.5 nM. The limit of detection is 2.0x10(-11) M (3sigma), with a relative standard deviation (n=11) of 1.9% for 3.5x10(-9) M cortisol. Eight human blood serum samples were all handled by solid-phase extraction (SPE) clean-up and enrichment before detection. This detection system is highly sensitive and convenient and may find wide applications. Based on the chemiluminescent spectra, a possible reaction mechanism is also suggested.