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210Pb and 210Po were used as tracers to determine the seasonal variations of residence times of aerosols (RTAs) in Shenzhen, China. The RTA for 210Pb/210Po aerosol particles ranged from 11.5 to 47.8 days (mean value of 25.3 ± 8.2 days), and it was lower in summer and higher in winter, meteorological conditions were considered the main factors affecting the RTA. The RTA was strongly affected by precipitation and was long under thermal inversions. In addition, the RTA calculated from the 210Po/210Pb ratio was strongly affected by old aerosols transported over long distances and the intrusion of upper atmospheric aerosols. [ABSTRACT FROM AUTHOR]

In order to understand detection of carotid atherosclerosis in the screening of high-risk stroke populations in a certain area of China, we have analyzed related risk factors of CAS. In accordance with the requirements of the "2015 Technical Plan for the Screening and Intervention Projects for High-Risk Stroke Populations," a cluster sampling method was used to select 4532 (number of screened persons from 2015 to 2021) permanent residents over 41 years old (一) in Shaheying Town, Liulin Town, Chenggu County, Hanzhong City, Shaanxi Province, and Da'an Town, Ningqiang County, and nearby communities are selected as the screening targets. We screened out high-risk groups of stroke based on big data technology and understood the detection of CAS. According to the screening results of big data technology, it was divided into two groups: CAS group and non-CAS group. The basic information, medical history, personal lifestyle, physical examination, and laboratory examination results of the two groups were classified and counted. The measurement data such as age and waist circumference of the two groups were tested by two independent samples, and the count data of gender, stroke history, hypertension, and other data were tested by the χ 2 test of the four-table data, and the logistic regression model was used to analyze the risk factors for CAS of population at high risk of stroke. The results proved the following: (1) Among the 4532 screeners, 865 cases were screened out of the high-risk population of stroke, with an average age of (58.5 ± 8.3) years, mainly 59 to 68 years old, accounting for 43.8%, and the male-to-female ratio was 1.6 : 1. (2) The detection rates of CAS, intimal thickening, plaque formation, and stenosis among high-risk groups of stroke were 55.5%, 10.2%, 52.2%, and 32.6%, respectively. (3) Among the high-risk groups of stroke, CAS patients have a history of stroke, the proportion of hypertension, age, total cholesterol, and low-density lipoprotein cholesterol levels that are higher than those in the non-CAS group, and the difference is statistically significant. (4) Logistic regression analysis shows that age, diabetes, and low-density lipoprotein cholesterol are independent risk factors for CAS in the high-risk population of stroke in this area. [ABSTRACT FROM AUTHOR]

Abstract: Molecular dynamics simulations were carried out to investigate both the structural and dynamical properties of water trapped inside a highly cross-linked polyamide RO membrane. The heterogeneous structure of the membrane was characterized through local water density and cavity size distributions. Interactions between water molecules and the polyamide membrane were investigated. Water structure and dynamics were explored and correlated with the heterogeneous distribution of the free volumes inside the membrane. [Copyright &y& Elsevier]

Ultra-precision measurement systems are important for semiconductor manufacturing processes. In a phase grating sensing alignment (PGA) system, the measurement accuracy largely depends on the intensity of the diffraction signal and its signal-to-noise ratio (SNR), both of which are associated with the grating structure. Although an equally segmented grating structure could increase the signal of a high odd order, it could also strengthen the signals at the zeroth and even orders which are the main contributors of stray light. This paper focuses on the practical problem of differently responding diffraction orders but in one grating structure. An analytical relationship has been established between the diffraction efficiency and the segment structure of phase grating. According to this analytic model, we then propose a design method to increase the diffraction signal at high odd orders and, meanwhile, to decrease it at the zeroth and even orders. The proposed method provides a fast and effective way to obtain the globally optimal grating structure in the valid scope. Furthermore, the design examples are also verified by means of numerical simulation tool–rigorous coupled-wave analysis (RCWA) software. As a result, the proposed method gives insight into the diffraction theory of segmented grating and the practical value to greatly improve the design efficiency. [ABSTRACT FROM AUTHOR]

We report molecular dynamics simulations of aqueous sodium chloride solutions at T = 298 K and p = 1 bar in order to investigate the salt concentration dependence of the dielectric permittivity, the structure, and the dynamical properties. Different models were applied up to 7 m salt concentration: the Drude oscillator model with a negative Drude particle (SWM4-NDP), the TIP4P/2005-Reif nonpolarizable model, and an electronic continuum polarizable model (MDEC). Both SWM4-NDP and MDEC polarizable models were able to quantitatively reproduce the concentration dependence of the dielectric permittivity of NaCl aqueous solutions. On the contrary, the nonpolarizable TIP4P/2005 water model failed to quantitatively predict this concentration dependence. In contrast with the SWM4-NDP model, the MDEC model was unable to capture the concentration dependence of the structure and the dynamics of NaCl solutions. The SWM4-NDP model proved to be the most efficient polarizable model to reproduce quantitatively the concentration dependence of the dielectric permittivity, the dynamics, and the structure of NaCl solutions.