Characteristics of hypertension in the last 16 years in high prevalence region of China and the attribute ratios for cardiovascular mortality.

BACKGROUND: Tianjin is one of the cities with the highest prevalence of hypertension in China and one of the first regions to develop community management of hypertension. Our aim was to analyze the characteristics of hypertension in the last 16 years, and estimate the population attributable fraction for cardiovascular mortality in Tianjin, China. METHODS: We compared the epidemiological characteristics of hypertension between 2002 and 2018 by analyzing data from the National Nutrition and Chronic Disease Risk Factor Survey. Subsequently, we obtained the cause-specific mortality in the same year from the Tianjin All Cause of Death Registration System (CDRS), and the population attributable fraction was used to estimate the annual cardiovascular disease (CVD) deaths caused by hypertension. RESULTS: In 2002 and 2018, the crude prevalence, awareness, treatment rate in diagnosed, control rate in treated, and overall control rate of hypertension were 36.6% and 39.8%, 36.0% and 51.9%, 76.0% and 90.1%, 17.4% and 38.3%, 4.8% and 17.9%, respectively (P < 0.05). The mean SBP for males between the ages of 25 and 50 was significantly higher in 2018 than in 2002. The number of CVD deaths attributed to hypertension was 13.8 thousand in 2002 (account for 59.1% of total CVD deaths), and increased to 21.7 thousand in 2018 (account for 58.8% of total CVD deaths). The population attributable fraction have increased in the age groups of 25-44 and 75 and above, and decreased in the age group of 45-74 from 2002 to 2018. CONCLUSIONS: Compare to 2002, the proportion of CVD deaths attributed to hypertension remains high, particularly among younger and older people, despite a very significant increase in treatment and control rates for hypertension in 2018.

High sodium diet intake and cardiovascular diseases: An attributable death study in Tianjin, China.

There is clear evidence that high sodium intake is associated with many health issues including hypertension and cardiovascular diseases (CVDs). Several national and worldwide studies have estimated deaths from CVDs attributable to high sodium. But how to evaluate the impact of high sodium intake on diseases using regional routine monitoring and investigation data is necessary and important. Our study aimed to quantitatively evaluate the high sodium intake attributed to CVDs deaths based on the routine monitoring data from China National Nutrition and Health Survey (CNNHS) in Tianjin, China. The population attributable fractions (PAF) were calculated by comparing the observed systolic blood pressure (SBP) distribution with the theoretical minimum or counterfactual distribution by sex and age groups. The results showed that CVDs deaths due to elevated SBP were 22728 (95% uncertainty intervals: 22679-23050), accounting for 62.8% of total CVDs deaths. According to sodium intake recommended by World Health Organization (WHO), PAF of CVDs deaths attributable to high sodium diet in our study was 14.6% of total CVDs deaths, accounting for 5228 (95% UI: 5005-5998) cases. The dietary sodium intake of residents is nearly three times than sodium intake recommended by WHO. If sodium intake was reduced to reference level, the potential avoidable CVD deaths attributable to the SBP-raising effect were more than 5200 among adults 25 aged and over in Tianjin. This evaluation method can be extended to other cities.

Two-dimensional IV-VA3 monolayers with enhanced charge mobility for high-performance solar cells.

High-performance photovoltaics (PVs) constitute a subject of extensive research efforts, in which silicon (Si)-based solar cells (SCs) have been widely commercialized. However, the low carrier mobility of Si-based SCs can limit the effective charge separation, thereby negatively impacting the device performance. Here, via calculating the physicochemical and PV performance based on density functional theory, we demonstrate SCs based on two-dimensional (2D) group IV and V compounds with an AX3 configuration. Firstly, the cleavage energies of AX3 (A = Si, Ge; X = P, As, and Sb) are calculated to be less than 1 J m-2, providing an experimental feasibility to be exfoliated from the corresponding bulk. Secondly, electronic and optical properties have been systematically investigated. To be specific, the band gap of monolayer AX3 falls in the range of 1.11-1.27 eV, which is comparable with that of Si. Significantly, the electron mobility of monolayer AX3 can reach as high as ∼30 000 cm2 V-1 s-1, which is one order of magnitude higher than that of Si. Furthermore, the optical absorbance of monolayer SiAs3, SiP3 and GeAs3 exhibits high coefficients in visible light. Therefore, we believe that our designed AX3-based PV systems with power conversion efficiency of 20% can offer great potential in the application of high-performance two-dimension-based PVs.

Two-dimensional InSb/GaAs- and InSb/InP-based tandem photovoltaic device with matched bandgap.

The past several years have witnessed remarkable research efforts to develop high-performance photovoltaics (PVs), to curtail the energy crisis by avoiding dependence on traditional fossil fuels. In this regard, there is an urgent need to accelerate research progress on new low-dimensional semiconductors with superior electronic and optical properties. Herein, combining abundant related PV experimental data in the literature and our systematic theoretical calculations, we propose two-dimensional (2D) InSb/GaAs and InSb/InP-based tandem PVs with high solar-to-electric efficiency up to near 30.0%. Firstly, according to first-principles calculations, the stability, electronic and optical properties of single-layer group-III-V materials (XY, X = Ga and In, Y = N, P, As, Sb, and Bi) are systematically introduced. Next, due to the high bandgap (Eg) of GaAs and InP being a perfect match with the low Eg of InSb, InSb/GaAs- and InSb/InP-based tandem PVs are constructed. In addition, the complementary absorption spectra of these two subcells can facilitate the achievement of high tandem power conversion efficiency. Furthermore, we have analyzed in detail the influencing factors for PCE and the physical mechanism of the optimized match between the top and bottom subcells in the tandem configurations. Our designed 2D-semiconductor-based PVs can be expected to bring a new perspective for future commercialized high-efficiency energy devices.

Two-Dimensional BAs/InTe: A Promising Tandem Solar Cell with High Power Conversion Efficiency.

Tandem solar cells (SCs) connecting two subcells with different absorption bands have the potential to reach the commercialized photovoltaic standard. However, the performance improvement of tandem architectures is still a challenge, primarily owing to the mismatch of band gaps in two subcells. Here, we demonstrate a two-dimensional (2D) BAs/InTe-based tandem SC, which could achieve solar-to-electric conversion efficiency higher than 30%. First, the narrow band gap of hexagonal single-layer BX (X = P and As) and wide band gap of single-layer YZ (Y = Ga and In, Z = S, Se, and Te) are found to have high thermodynamic stability based on density functional theory calculations. Next, considering narrow and wide band gaps at the HSE06 functional, single-layer BX/YZ-based tandem SCs are built to effectively capture a broad-band solar spectrum by combining such two subcells. Since the band gap of single-layer BAs matches well with that of the InTe monolayer, the power conversion efficiency of BAs/InTe-based tandem SC can reach as high as 30.2%. Moreover, it is important to note that the used materials, including few-layer GaZ and InSe, have been experimentally prepared, which strongly supports the high feasibility of the designed 2D tandem SCs in this work. Our constructed 2D-material-based devices can be competitive in realizing commercialized high-performance tandem SCs.

Two-dimensional aluminum phosphide semiconductor with tunable direct band gap for nanoelectric applications.

More and more attractive applications of two-dimensional (2D) materials in nanoelectronic devices are being achieved successfully, which promotes the rapid and extensive development of new 2D materials. In this work, the structural and electronic properties of the V structure aluminum phosphide (V-AlP) monolayer are examined by density functional calculations, and its electronic properties under strain and an electric field are also explored in detail. The computation results indicate that it has good stability. Interestingly, it possesses a wide direct gap (2.6 eV), and its band gap exhibits a rich behavior depending on the strain, E-field and layer stacking. Under biaxial strain, its band gap can be tuned from 1 eV to 2.6 eV. And a direct-indirect band gap transition is found when external tension is applied. The V-AlP monolayer also exhibits anisotropic behavior as its band structure variation trends under strains along different directions are obviously different. When the external E-field is changed from 0.5 V Å-1 to 1 V Å-1, the band gap of the V-AlP monolayer can be tuned linearly from 0 eV to 2.6 eV. Layer stacking narrows the band gap of the 2D V-AlP material. It is concluded that strain, E-field and layer stacking can all be used effectively to modify the electronic property of the V-AlP monolayer. Thus, these results indicate that the V-AlP monolayer will have promising applications in nanoelectric devices.

Two-dimensional BX (X = P, As, Sb) semiconductors with mobilities approaching graphene.

Carrier mobility plays a key role in the performance of microelectronic devices, especially the field effect transistors (FET). To design next generation two-dimensional (2D) FET, stable channel materials with a higher carrier mobility than silicon and a significant band gap are highly desirable, but are still not discovered. Here, we report a group of 2D materials of BX (X = P, As, and Sb), which are semiconducting with an ultrahigh carrier mobility. Using first-principles calculations, we find that all BX configurations are similar to graphene, but possess direct bandgaps of 1.36, 1.14, and 0.49 eV, respectively. Based on deformation potential theory, BX monolayers are predicted to have superior mobilities (>10(4) cm(2) V(-1) s(-1)) to phosphorene. In particular, the electron mobility of monolayer BSb is 3.2 × 10(5) cm(2) V(-1) s(-1), approaching the figure of merit in graphene (∼3 × 10(5) cm(2) V(-1) s(-1)). These results demonstrate that BX monolayers are of paramount significance for next-generation 2D FET manufacture.

Two-dimensional GeS with tunable electronic properties via external electric field and strain.

Experimentally, GeS nanosheets have been successfully synthesized using vapor deposition processes and the one-pot strategy. Quite recently, GeS monolayer, the isoelectronic counterpart of phosphorene, has attracted much attention due to promising properties. By means of comprehensive first-principles calculations, we studied the stability and electronic properties of GeS monolayer. Especially, electric field and in-plane strain were used to tailor its electronic band gap. Upon applying electric field, the band gap of GeS monolayer greatly reduces and a semiconductor-metal transition happens under the application of a certain external electric field. Our calculations reveal that the band gaps of GeS monolayer are rather sensitive to the external electric field. On the other hand, for GeS under external strain, quite interestingly, we found that the band gap presents an approximately linear increase not only under compression strain but also under tensile strain from -10% to 10%. For biaxial compressive and tensile strains, the band gap follows the same trend as that of the uniaxial in the zigzag x direction. The present results provide a simple and effective route to tune the electronic properties of GeS monolayer over a wide range and also facilitate the design of GeS-based two-dimensional devices.

Semiconducting Group†15 Monolayers: A Broad Range of Band Gaps and High Carrier Mobilities.

Optoelectronic applications require materials both responsive to objective photons and able to transfer carriers, so new two-dimensional (2D) semiconductors with appropriate band gaps and high mobilities are highly desired. A broad range of band gaps and high mobilities of a 2D semiconductor family, composed of monolayer of Group 15 elements (phosphorene, arsenene, antimonene, bismuthene) is presented. The calculated binding energies and phonon band dispersions of 2D Group 15 allotropes exhibit thermodynamic stability. The energy band gaps of 2D semiconducting Group 15 monolayers cover a wide range from 0.36 to 2.62 eV, which are crucial for broadband photoresponse. Significantly, phosphorene, arsenene, and bismuthene possess carrier mobilities as high as several thousand cm(2) V(-1) s(-1) . Combining such broad band gaps and superior carrier mobilities, 2D Group 15 monolayers are promising candidates for nanoelectronics and optoelectronics.