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β-N-methylamino-l-alanine (BMAA), which has been considered as an environmental factor that caused amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) or Alzheimer's disease, could be produced by a variety of genera cyanobacteria. BMAA is widely present in water sources contaminated by cyanobacteria and may threaten human health through drinking water. Although oxidants commonly used in drinking water plants such as chlorine, ozone, hydrogen peroxide, and hydroxyl radicals have been shown to effectively degrade BMAA, there are limited studies on the mechanism of BMAA degradation by different oxidants, especially ozone. This work systematically explored the effectiveness of BMAA ozonation degradation, investigated the effect of the operating parameters on the effectiveness of degradation, and speculated on the pathways of BMAA decomposition. The results showed that BMAA could be quickly eliminated by ozone, and the removal rates of BMAA were nearly 100% in pure water, but the removal rates were reduced in actual water. BMAA was primarily degraded by direct oxidation of ozone molecules in acidic and near-neutral conditions, and indirect oxidation of •OH accounted for the main part under strong alkaline conditions. The pH value had a significant effect on the decomposition of BMAA, and the degradation rate of BMAA was fastest at near-neutral pH value. The degradation rates of TOC were significantly lower than that of BMAA, indicating that by-products were generated during the degradation process. Three by-products ([M-H]+ = 105, 90, and 88) were identified by UPLC-MS/MS, and the degradation pathways of BMAA were proposed. The production of by-products was attributed to the fracture of the C–N bonds. This work is helpful for the in-depth understanding on the mechanism and demonstration of the feasibility of the oxidation of BMAA by the ozone process. Highlights: • The reaction of ozonation BMAA was easy to occur. • The degradation rate was fast under near-neutral conditions. • Direct oxidation under neural conditions was the main pathway for ozone degradation of BMAA. • Three products were detected, and the reaction path was inferred. [ABSTRACT FROM AUTHOR]

Natural gas, which is mainly composed of methane, plays an important role in energy consumption. Nevertheless, natural gas leakage induced by damage of moving parts seriously affects the ecological environment and social security. It is an effective strategy to coat amorphous carbon (a-C) film on moving parts for this issue. In order to supplement the knowledge about frictional mechanism of a-C film in methane atmosphere, the roles of passivation and graphitization were explored by means of deposition target currents and thermal annealing. The results indicated that carbon target currents and thermal annealing were significant to the structures and tribological performances of a-C films under methane. It was also obtained that graphitization induced by shearing greatly enhanced the wear resistance of a-C film and the passivation of carbon dangling bonds reduced friction coefficients of a-C films in methane atmosphere. This study on the mechanism of friction properties of a-C films under methane provides guidance for the preparation of low friction and wear resistance films in methane atmosphere. [ABSTRACT FROM AUTHOR]

Multilayered Si-doped DLC film with thicknesses of 5.5, 10.1, 21.8 and 28.3 μm was deposited on stainless steel, aluminum alloy and copper alloy substrates by plasma-enhanced chemical vapor deposition. The mechanical and tribological properties of multilayered Si-doped DLC films deposited on three different substrates were evaluated in this study. The hardness of the multilayered Si-doped DLC film of different substrates is related to the substrate material and internal stress. In a scratch test, the adhesion of the multilayered Si-doped DLC film increased with the film thickness. The multilayered Si-doped DLC film with a thickness of 28.3 μm on stainless steel substrate has the highest adhesion of 31 N. The adhesion of the multilayered Si-doped DLC film with different thicknesses on the copper alloy is relatively poor. The ball-on-disk friction test results show that the multilayered Si-doped DLC film with thicknesses of 5.5 and 10.1 μm is prone to shear deformation and exhibit high friction coefficient. The uneven stress distribution and surface deformation of the multilayered Si-doped film deposited on the aluminum alloy and the copper alloy cause the fluctuation and rise of the friction coefficient. The wear resistance of multilayered Si-doped DLC films on different substrates is related to stress shielding and adhesion strength. [ABSTRACT FROM AUTHOR]

Friction pairs are regarded significantly as one unified system to avert excessive energy and material loss caused by friction in harsh environment taking into account of its complicated physical and chemical process in the friction interface. Here, we carried out the experiment of Cr-doped diamond-like carbon (Cr-DLC) sliding against different counterparts in hydrochloric acid (HCl) in order to find a better solution for the tribocorrosion failure of Cr-DLC in harsh environment. The results indicated that the material of counterparts and interfacial tribochemical products had significant impact on the friction behavior of Cr-DLC. The friction coefficients of Cr-DLC sliding against different counterparts were highly dependent with the associated Hertzian contact radius calculated by the Hertzian contact theory, while the wear rates were related to the interfacial tribochemical products in HCl. Moreover, the hardness ratio and the elastic energy density of friction pair were introduced to analysis the wear behavior of Cr-DLC film sliding against mated materials. All of the results indicated that the Cr-DLC film sliding against tetrahedral amorphous carbon (ta-C) showed the most outstanding tribological performance. Understanding the fundamental mechanism of Cr-DLC film sliding against different counterpart materials would expand the practical application of Cr-DLC thin film in corrosive environment. [ABSTRACT FROM AUTHOR]

Introduction: The method of time-to-onset (TTO) has been proposed to overcome the drawbacks of traditional disproportionality analyses (DPAs), and it has been used for detecting safety signals of vaccines and some non-vaccine products in spontaneous reporting systems (SRSs). However, there is no consensus on its superiority over DPAs. Further, it is still not clear whether this novel approach can be generalized to the entire national SRS database.Objective: The purpose of this study was to generalize the TTO method to the Chinese SRS and to identify suitable parameters for its optimal performance.Methods: Reports submitted to the national SRS of China in 2014 were used as the data source for analysis. We evaluated the performance of TTO by using product labels as proxies for the gold standard. A series of values of significance level and time windows were explored to identify the most suitable parameters for TTO based on Youden's index, a statistic that summarizes the performance of a diagnostic test. Additionally, we compared TTO with traditional DPAs and explored the characteristics of signals detected by these methods.Results: Compared with DPAs, TTO had a lower sensitivity, but higher specificity and positive predictive value. At a significance level of 0.2 and no restrictions on time windows, TTO had the highest Youden's index. The kappa coefficients between TTO and DPAs were rather low, indicating poor agreement between the two methods. More than 30% of the true signals detected by TTO were not identified by DPAs. Furthermore, TTO needed more number of reports to be able to detect signals.Conclusions: TTO can detect signals missed by traditional DPAs and could be an important complementary tool to the currently used DPAs in the SRS of China. We recommend a significance level of 0.2 and no restrictions on time windows for TTO. [ABSTRACT FROM AUTHOR]

It has been more than 25 years since an adverse drug reaction (ADR) monitoring agency was first established in China. In the past few years, the National ADR Monitoring System (NADRMS) has developed rapidly in the country. However, this system has not been reviewed in detail in the literature. Our aim was to demonstrate how individual case safety reports (ICSRs) are reported and evaluated and how data quality control is achieved in China. We also aimed to discuss the present status and future of NADRMS. We reviewed the relevant regulations and literature around ADR reporting in China. ADR report collection tools in China have gone through three phases, namely paper-based reporting, software-based reporting using standalone computers, and online reporting. Nowadays the online reporting system plays an important role in China and the number of ADR reports has rapidly increased. NADRMS is similar to most of the ADR reporting systems around the world, but also has its own unique characteristics such as four levels of monitoring agencies. In summary, there is still a long way to go for China to establish a high-level ADR monitoring system to ensure drug safety. [ABSTRACT FROM AUTHOR]