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In December 2019, the first confirmed case of pneumonia caused by a novel coronavirus was reported. Coronavirus disease 2019 (COVID-19) is currently spreading around the world. The relationships among the pandemic and its associated travel restrictions, social distancing measures, contact tracing, mask-wearing habits and medical consultation efficiency have not yet been extensively assessed. Based on the epidemic data reported by the Health Commission of Wenzhou, we analysed the developmental characteristics of the epidemic and modified the Susceptible-Exposed-Infectious-Removed (SEIR) model in three discrete ways. (1) According to the implemented preventive measures, the epidemic was divided into three stages: initial, outbreak and controlled. (2) We added many factors, such as health protections, travel restrictions and social distancing, close-contact tracing and the time from symptom onset to hospitalisation (TSOH), to the model. (3) Exposed and infected people were subdivided into isolated and free-moving populations. For the parameter estimation of the model, the average TSOH and daily cured cases, deaths and imported cases can be obtained through individual data from epidemiological investigations. The changes in daily contacts are simulated using the intracity travel intensity (ICTI) from the Baidu Migration Big Data platform. The optimal values of the remaining parameters are calculated by the grid search method. With this model, we calculated the sensitivity of the control measures with regard to the prevention of the spread of the epidemic by simulating the number of infected people in various hypothetical situations. Simultaneously, through a simulation of a second epidemic, the challenges from the rebound of the epidemic were analysed, and prevention and control recommendations were made. The results show that the modified SEIR model can effectively simulate the spread of COVID-19 in Wenzhou. The policy of the lockdown of Wuhan, the launch of the first-level Public Health Emergency Preparedness measures on 23 January 2020 and the implementation of resident travel control measures on 31 January 2020 were crucial to COVID-19 control.
A novel, broadband, nonlinear behavioral model, based on support vector regression (SVR) is presented in this paper. The proposed model, distinct from existing SVR-based models, incorporates frequency information into its formalism, allowing the model to perform accurate prediction across a wide frequency band. The basic theory of the proposed model, along with model implementation and the model extraction procedure for radio frequency transistor devices is provided. The model is verified through comparisons with the simulation of an equivalent circuit model, as well as experimental measurements of a 10 W Gallium Nitride (GaN) transistor. It is seen that the efficiency prediction throughout the Smith chart, for varying fundamental and second harmonic loads, across a wideband frequency range, show excellent fidelity to the measured results. Device dc self-biasing is also modelled to allow prediction of power amplifier (PA) efficiency, which is shown to be highly accurate when compared with corresponding measured data. Finally, a class-J PA is constructed and measured across the frequency with a large-signal input tone. The resulting measured and modelled values of key PA performance figures are shown to be in excellent agreement, indicating the model is suitable for broadband PA design.
Nickel-coated carbon nanotubes (Ni-CNTs) were achieved by electroless plating. Laser cladded IN718 and IN718 with 10, 30, and 50 wt% additions of Ni-CNTs were fabricated. The structural evolution of CNTs in the laser-deposited layers was studied; the microstructure, tensile, and wear properties of the laser-cladded alloys were characterized. The results show that CNTs in the laser-deposited layers are mostly transformed to carbon nanoproducts (CNPs) in the forms of graphene nanosheets, graphene fragments, carbon nanoribbons, and diamond-like nanoparticles by unzipping, interbonding, collapsing, and curvature of CNTs. The interdendritic Laves phase formation is dramatically depressed due to the addition of Ni-CNTs, but the excess addition of the Ni-CNTs can undesirably increase the formation of NbC. The addition of Ni-CNTs effectively improves the tensile and wear properties. The most superior tensile and wear properties are achieved in the layers with 30 and 50 wt% additions of Ni-CNTs, respectively. The generation of intermetallic phase and CNPs are revealed to be two dominant effects both on the tensile and wear properties of the laser-cladded alloys.
In order to maintain the no-slip condition and the divergence-free property simultaneously, an iterative scheme of immersed boundary method in the finite element framework is presented. In this method, the Characteristic-based Split scheme is employed to solve the momentum equations and the formulation for the pressure and the extra body force is derived according to the no-slip condition. The extra body force is divided into two divisions, one is in relation to the pressure and the other is irrelevant. Two corresponding independent iterations are set to solve the two sections. The novelty of this method lies in that the correction of the velocity increment is included in the calculation of the extra body force which is relevant to the pressure and the update of the force is incorporated into the iteration of the pressure. Hence, the divergence-free properties and no-slip conditions are ensured concurrently. In addition, the current method is validated with well-known benchmarks.
The plasma in the scrape-off layer (SOL) has an important effect on the coupling of the waves in the ion cyclotron range of frequencies (ICRF). The high-frequency B-dot (HFB) probes have been installed to investigate the behaviour of ICRF waves on EAST. The fast and slow ICRF wave field amplitudes are measured and a domain parallel wavenumber is deduced. Results of measurements on a test experimental platform and EAST experiments are presented, which include vacuum and plasma situations. In vacuum it is found that field amplitudes increase linearly with ICRF power. Besides, during plasma operation, field amplitudes measured were decreased by an order of magnitude and no linear relation with power was observed. Fast and slow wave power densities fluctuate strongly with plasma density. The experimental results in the laboratory coincide with the simulation results and allow for validating of the measurement method.
The piezophotonic effect is the coupling between piezoelectric properties and photoexcitation, where strain-induced piezopotential modulates and controls the relevant optical process. Specifically, metal ions as activators are capable of responding to photoexcitation and subsequent emission of light, also called mechanoluminescence, in general, and piezoluminescence specifically for piezoelectrics. These phenomena are helpful for understanding the materials fundamentals and conceiving widespread device applications. In this article, we briefly introduce the physical mechanisms of piezophotonics, including piezoluminescence. Selected host materials and metal-ion activators are described for demonstrating the piezophotonic effect. We provide a unified profile and recent prototypical demonstrations of light emission triggered by mechanical stimuli. The devices based on these materials offer the advantages of remote detection, nondestructive analysis, and repeatability, hence they are promising candidates for applications in stress sensing, structural health diagnosis, three-dimensional handwriting, magnetic-optical sensing, energy harvesting, biomedicine, novel light sources, and displays.
Al–12.6Si was annealed at both 500 and 560 °C for different lengths of time in this study. Additionally, the effects of annealing treatment on the spheroidization of eutectic Si and the mechanical properties of the Al–Si alloy have been investigated. The morphology of these particles was described using surface shape factor (φ), and it was found that the optimal annealing time of Al–12.6Si at 500 and 560 °C is seven hours and five hours, respectively. The average size of the Si particles in the Al–Si alloy annealed at 500 °C is less than that of the particles at 560 °C. The roundness of the Si particles within the Al–Si alloy annealed at 500 °C is slightly better than that at 560 °C. The elongation of the alloy apparently increases, while the tensile strength of the Al–Si alloy decreases. The tensile strength and elongation of the eutectic Al–Si alloy annealed at 500 °C is higher than that at 560 °C.
Psychiatric disorders such as schizophrenia and major depressive disorder
(MDD) are likely to be caused by multiple susceptibility genes, each with
small effects in increasing the risk of illness. Identifying DNA variants
associated with schizophrenia and MDD is a crucial step in understanding
the pathophysiology of these disorders.
To investigate whether the SP4 gene plays a significant
role in schizophrenia or MDD in the Han Chinese population.
We focused on nine single nucleotide polymorphisms (SNPs) harbouring the
SP4 gene and carried out case–control studies in 1235
patients with schizophrenia, 1045 patients with MDD and 1235 healthy
controls recruited from the Han Chinese population.
We found that rs40245 was significantly associated with schizophrenia in
both allele and genotype distributions (Pallele = 0.0005, Pallele = 0.004 after Bonferroni correction; Pgenotype = 0.0023, Pgenotype = 0.0184 after Bonferroni correction). The rs6461563
SNP was significantly associated with schizophrenia in the allele
distributions (Pallele = 0.0033, Pallele = 0.0264 after Bonferroni correction).
Our results suggest that common risk factors in the SP4
gene are associated with schizophrenia, although not with MDD, in the Han
A large schizophrenia genome-wide association study (GWAS) and a
subsequent extensive replication study of individuals of European
ancestry identified eight new loci with genome-wide significance and
suggested that the MIR137-mediated pathway plays a role
in the predisposition for schizophrenia.
To validate the above findings in a Han Chinese population.
We analysed the single nucleotide polymorphisms (SNPs) in the newly
identified schizophrenia candidate loci and predicted
MIR137 target genes based on our published Han
Chinese populations (BIOX) GWAS data. We then analysed 18 SNPs from the
candidate regions in an independent cohort that consisted of 3585
patients with schizophrenia and 5496 controls of Han Chinese
We replicated the associations of five markers
(P<0.05), including three that were located in the
predicted MIR137 target genes. Two loci
(ITIH3/4: rs2239547, P
=1.17×10–10 and CALN1: rs2944829,
P=9.97×10–9) exhibited genome-wide
significance in the Han Chinese population.
The ITIH3/4 locus has been reported to be of genome-wide
significance in the European population. The successful replication of
this finding in a different ethnic group provides stronger evidence for
the association between schizophrenia and ITIH3/4. We
detected the first genome-wide significant association of schizophrenia
with CALN1, which is a predicted target of
MIR137, and thus provide new evidence for the
associations between MIR137 targets and
Fractures are important for shale-gas reservoirs with low matrix porosity because they increase the effective reservoir space and migration pathways for shale gas, thus favouring an increased volume of free gas and the adsorption of gases in shale reservoirs, and they increase the specific surface area of gas-bearing shales which improves the adsorption capacity. We discuss the characteristics and dominant factors of fracture development in a continental organic matter-rich shale reservoir bed in the Yanchang Formation based on observations and descriptions of fracture systems in outcrops, drilling cores, cast-thin sections and polished sections of black shale from the Upper Triassic Yanchang Formation in the SE Ordos Basin; detailed characteristics and parameters of fractures; analyses and tests of corresponding fracture segment samples; and the identification of fracture segments with normal logging. The results indicate that the mineral composition of the continental organic-matter-rich shale in the Yanchang Formation is clearly characterized by a low brittle mineral content and high clay mineral content relative to marine shale in the United States and China and Mesozoic continental shale in other basins. The total content of brittle minerals, such as quartz and feldspar, is c. 41%, with quartz and feldspar accounting for 22% and 19% respectively, and mainly occurring as plagioclase with small amounts of carbonate rocks. The total content of clay minerals is high at up to 52%, and mainly occurs as a mixed layer of illite-smectite (I/S) which accounts for more than 58% of the total clay mineral content. The Upper Triassic Yanchang Formation developed two groups of fracture (joint) systems: a NW–SE-trending system and near-E–W-trending system. Multiple types of fractures are observed, and they are mainly horizontal bedding seams and low-dip-angle structural fractures. Micro-fractures are primarily observed in or along organic matter bands. Shale fractures were mainly formed during Late Jurassic – late Early Cretaceous time under superimposed stress caused by regional WNW–ESE-trending horizontal compressive stress and deep burial effects. The extent of fracture development was mainly influenced by multiple factors (tectonic factors and non-tectonic factors) such as the lithology, rock mechanical properties, organic matter abundance and brittle mineral composition and content. Specifically, higher sand content has been observed to correspond to more rapid lithological changes and more extensive fracture development. In addition, higher organic matter content has been observed to correspond to greater fracture development, and higher quartz, feldspar and mixed-layer I/S contents have been observed to correspond to more extensive micro-fracture development. These results are consistent with the measured mechanical properties of the shale and silty shale, the observations of fractures in cores and thin-sections from more than 20 shale-gas drilling wells, and the registered anomalies from gas logging.
To evaluate vitamin D deficiency prevalence and risk factors among pregnant Chinese women.
A descriptive cross-sectional analysis.
China National Nutrition and Health Survey (CNNHS) 2010–2013.
A total of 1985 healthy pregnant women participated. Possible predictors of vitamin D deficiency were evaluated via multiple logistic regression analyses.
The median serum 25-hydroxyvitamin D level was 15·5 (interquartile range 11·9–20·0, range 3·0–51·5) ng/ml, with 74·9 (95 % CI 73·0, 76·7) % of participants being vitamin D deficient (25-hydroxyvitamin D <20 ng/ml). According to the multivariate logistic regression analyses, vitamin D deficiency was positively correlated with Hui ethnicity (P=0·016), lack of vitamin D supplement use (P=0·021) and low ambient UVB level (P<0·001). In the autumn months, vitamin D deficiency was related to Hui ethnicity (P=0·012) and low ambient UVB level (P<0·001). In the winter months, vitamin D deficiency was correlated with younger age (P=0·050), later gestational age (P=0·035), higher pre-pregnancy BMI (P=0·019), low ambient UVB level (P<0·001) and lack of vitamin D supplement use (P=0·007).
Vitamin D deficiency is prevalent among pregnant Chinese women. Residing in areas with low ambient UVB levels increases the risk of vitamin D deficiency, especially for women experiencing advanced stages of gestation, for younger pregnant women and for women of Hui ethnicity; therefore, vitamin D supplementation and sensible sun exposure should be encouraged, especially in the winter months. Further studies must determine optimal vitamin D intake and sun exposure levels for maintaining sufficient vitamin D levels in pregnant Chinese women.
The prevalence and factors associated with delays in help seeking for people with dementia in China are unknown.
Within 1,010 consecutively registered participants in the Clinical Pathway for Alzheimer's Disease in China (CPAD) study (NCT01779310), 576 persons with dementia (PWDs) and their informants reported the estimated time from symptom onset to first medical visit seeking diagnosis. Univariate analysis of general linear model was used to examine the potential factors associated with the delayed diagnosis seeking.
The median duration from the first noticeable symptom to the first visit seeking diagnosis or treatment was 1.77 years. Individuals with a positive family history of dementia had longer duration (p = 0.05). Compared with other types of dementia, people with vascular dementia (VaD) were referred for diagnosis earliest, and the sequence for such delays was: VaD < Alzheimer's disease (AD) < frontotemporal dementia (FTD) (p < 0.001). Subtypes of dementia (p < 0.001), family history (p = 0.01), and education level (p = 0.03) were associated with the increased delay in help seeking.
In China, seeking diagnosis for PWDs is delayed for approximately 2 years, even in well-established memory clinics. Clinical features, family history, and less education may impede help seeking in dementia care.
White sponge nevus (WSN) in the oral mucosa is a rare autosomal dominant genetic disease. The involved mucosa is white or greyish, thickened, folded and spongy. The genes associated with WSN include mutant cytokeratin keratin 4 (KRT4) and keratin 13 (KRT13). In recent years, new cases of WSN and associated mutations have been reported. Here, we summarise the recent progress in our understanding of WSN, including clinical reports, genetics, animal models, treatment, pathogenic mechanisms and future directions. Gene-based diagnosis and gene therapy for WSN may become available in the near future and could provide a reference and instruction for treating other KRT-associated diseases.
The ZrO2 and graphitic carbon nitride (g-C3N4) composite photocatalyst has been prepared by calcination process and hydrothermal treatment. The photocatalyst was characterized by x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy, UV–vis diffuse reflection spectroscopy, Brunauer–Emmett–Teller and photoluminescence spectra. The photocatalytic activity of the photocatalysts was evaluated by degradation of methylene blue under visible light irradiation. The results showed that the activity of the composite photocatalyst ZrO2/g-C3N4 for photodegradation of MB is much higher than that of either pure g-C3N4 or ZrO2, which is ascribed to the effective electron–hole separation based on the photoluminescence spectra. The •O2− might be the main active species in MB photodegradation, and the •OH and photogenerated electrons are also partly involved in the process of photocatalytic degradation.
It is widely accepted that oxygen will severely deteriorate the glass-forming ability (GFA) of an alloy. In this work, we report that the GFA of a Fe76Si9B10P5 glassy alloy can be significantly improved (the critical diameter for fully glass formation is increased from 1 to 3 mm) under oxygen casting atmosphere. Furthermore, the pressure of oxygen atmosphere gives an obvious enhancement in the critical diameter of Fe76Si9B10P5 glassy alloy. A dependence of GFA on casting atmosphere species (argon, nitrogen, air, and oxygen) is also observed for this glassy alloy, and its critical diameter is 1, 1.5, 2.5, and 3 mm, respectively. In addition, the Fe-based glassy alloy exhibits excellent soft magnetic properties regardless of the applied casting atmosphere. The mechanism for such an unusual oxygen effect on the GFA of Fe76Si9B10P5 glassy alloy is attributed to the reduced nucleation rate caused by the enhancement of surface tension of the alloy melt.
Common psychiatric disorders are highly heritable, indicating that genetic factors play an important role in their aetiology. The CACNA1C gene, which codes for subunit alpha-1C of the Cav1.2 voltage-dependent L-type calcium channel, has been consistently found to be the shared risk gene for several kinds of mental disorder.
To investigate whether CACNA1C is a susceptibility gene for schizophrenia and major depressive disorder in the Han Chinese population.
We carried out a case–control study of 1235 patients with schizophrenia, 1045 with major depressive disorder and 1235 healthy controls. A tag single nucleotide polymorphism (SNP) rs1006737 along with another 10 tag SNPs in the CACNA1C gene were genotyped in all samples.
We found that rs1006737 was associated with both schizophrenia (Pallele = 0.0014, Pgenotype = 0.006, odds ratio (OR) = 1.384, 95% CI 1.134–1.690) and major depressive disorder (Pallele = 0.0007, Pgenotype = 0.003, OR = 1.425, 95% CI 1.160–1.752).
Our findings support CACNA1C being a risk gene for both schizophrenia and major depressive disorder in the Han Chinese population.
China is experiencing a rapid increase in overweight and related conditions. This study describes the geographic variation in BMI levels and the prevalence of overweight and underweight in Chinese adults, and assesses their relations with regional Gross Domestic Product (GDP) per capita levels. BMI values and the prevalence of overweight and underweight in 143 522 adults from the Chinese National Nutrition and Health Survey (2002) were calculated according to geographic regions in China. Their correlations with GDP were assessed. Linear and logistic regressions were used to adjust for age, sex and city–country composition. BMI and the prevalence of overweight were highest in the Bohai coastal regions while lowest in southern provinces such as Guangdong, Guangxi, Yunnan, Hunan and Fujian. Mean BMI values ranged from 20·72 to 25·48 kg/m2, and the prevalence of overweight ranged from 6·6 to 53·9 %. BMI and the prevalence of overweight were positively correlated with economic development, particularly in the northern regions. However, for regions with similar GDP per capita levels, those in the south had substantially lower BMI and lower prevalence of overweight than those in the north. Interestingly, some southern regions with high GDP per capita had low BMI and low prevalence of overweight. The prevalence of underweight was highest in the south. Substantial geographic variations in the prevalence of overweight and underweight exist in China. Such variations cannot be fully explained by the differences in economic status. China is currently facing challenges of both overweight and underweight but priorities vary in different regions.
A high power conversion efficiency above 1% from a bulk crystalline silicon (c-Si) light-emitting diode (LED) has been demonstrated at near room temperature. These devices are based on normally weak one- and two-phonon assisted sub-bandgap light emission processes. Their improved performance results from device designs that take advantage of enhanced light absorption by a light trapping scheme which was developed for high efficiency silicon solar cells, and from reducing scope for parasitic non-radiative recombination within the diode. Each feature individually is shown to improve efficiency by a factor of ten, accounting for an improvement by factor of one hundred compared to baseline devices.
Also demonstrated is a greatly improved band-edge light emission and detection using bulk c-Si diodes. A bulk c-Si LED is combined with a similar diode used as a detector that collects the light emitted with a high quantum collection efficiency of 33%, to produce a silicon to silicon optically coupled system that demonstrates 0.18% coupling quantum efficiency. The crystalline silicon LED demonstrates similarly high performance at very low power levels, where it has even higher power efficiency than a high efficiency GaAlAs LED.
Pure and neodymium-doped gadolinium calcium oxoborate crystals of high quality were grown by the Czochralski method. The orientation of crystal was precisely determined, and the samples for measurements were prepared. Through synchrotron x-ray topography and high-resolution x-ray diffractometry, the twin structure was discovered. Some properties such as the figure of merit value, and dielectric, piezoelectric, and elastic constants were measured along with a discussion of the anisotropy of the laser properties.
Solidification of FeSi2 alloy by single-roller rapid solidification technology was studied, and monophase α–FeSi2 ribbons were obtained. Phase evolution of the monophase and metastable α–FeSi2 ribbons during subsequent annealing was studied with in situ electric resistance measurements. The results show that the metastable α–FeSi2 phase transforms into the β–FeSi2 phase at about 620 °C and then transforms into the α–FeSi2 phase again at a higher temperature when heated. A new relatively simple method to prepare bulk β–FeSi2 alloy, that is, formation of bulk β–FeSi2 alloy by annealing monophase α–FeSi2 alloy, is presented.