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Abstract Background The Chinese central government launched the third phase of health system reforms in 2009. After a decade since the initiation of the reform, the health system has witnessed noteworthy gains. However, there is no concurrent improvement in public satisfaction with the health system. This study analysed various factors that influence public satisfaction with the system and examined whether perceived quality of care affects public satisfaction. Methods A longitudinal nationally representative survey was used for this study. We used five waves of China Family Panel Studies (CFPS) survey data. The final sample consisted of 145 843 observations. A two-way fixed-effects ordered logistic model was used for the analysis. Results The results indicate that perceived good quality of care was positively associated with public satisfaction in health system regardless of rural–urban residence. Older adults and individuals with more than 3 years of college education were less likely to be satisfied with the system in rural areas. Personal income and the density of medical professionals in the geographic area tend to improve public satisfaction in rural areas. Having medical insurance coverage and fair or good self-rated health improved the probability of reporting public satisfaction in urban areas. Married people and individuals who lived in the West region were less likely to be satisfied with the health system in urban areas. Conclusions Knowledge and skills of healthcare providers or physical quality of facilities are not sufficient in improving public satisfaction in the health system. Policymakers need to identify options to influence the important factors that affect public perception of the system. This analysis identified several policy-amenable factors to improve public perception of the health system in rural and urban China.

Abstract We propose that the double barrier effect is expected to enhance the tunneling electroresistance (TER) in the ferroelectric tunnel junctions (FTJs). To demonstrate the feasibility of this mechanism, we design a model structure of Pt/BaTiO3/LaAlO3/Pt/BaTiO3/LaAlO3/Pt double barrier ferroelectric tunnel junction (DB-FTJ), which can be considered as two identical Pt/BaTiO3/LaAlO3/Pt single barrier ferroelectric tunnel junctions (SB-FTJs) connected in series. Based on density functional calculation, we obtain the giant TER ratio of 2.210 × 108% in the DB-FTJ, which is at least three orders of magnitude larger than that of the SB-FTJs of Pt/BaTiO3/LaAlO3/Pt, together with an ultra-low resistance area product (0.093 KΩμm2) in the high conductance state of the DB-FTJ. Moreover, it is possible to control the direction of polarization of the two single ferroelectric barriers separately and thus four resistance states can be achieved, making DB-FTJs promising as multi-state memory devices.

Within the context of mounting competition faced by Hollywood movies in the global cinema market, particularly in emerging markets, this paper examines the influence of review disagreements and cultural capital on the cultural discount of imported Hollywood blockbusters in China's movie market. Using a dataset of 652 movies from the U.S. spanning 1994–2019, we find that review disagreements between U.S. and Chinese consumers exacerbate the cultural discount on imported Hollywood movies in China. However, cultural capital, measured by the accumulated revenue of specific imported movie genres in China, effectively mitigates this discount. We also observe a reduction in the discount for movie genres with fewer language barriers. Accounting for endogeneity due to reverse causality and selection bias, we identify a significant structural break in 2012. In the post-2012 era, collaboration involving China's censorship, quota rules, and film-production laws has improved the market mechanism and cultural capital accumulation, enhancing the performance of imported Hollywood movies in China. Minority movies, characterized by being less mainstream and commercial, are more sensitive to review disagreements, while cultural capital plays a greater role in mitigating the discount for mainstream Hollywood movies. These findings have significant implications for professionals involved in the distribution and screening of Hollywood movies in China.

IntroductionUnderstanding the factors that affected academic performance of students during the COVID-19 pandemic will help design effective interventions for improving students’ academic performance during emergency situations as well as during regular academic environment. This cross-sectional study aimed to identify the factors that explain academic performance of students in China during the pandemic.MethodsData on college students from the 2020 China Family Panel Studies were used, and the final sample consisted of 728 students. Ordered probit regression models were estimated to explain students’ relative performance in the semester when the in-person classes were suspended by using various student and household-related variables and characteristics. To compute missing values in selected variables, a multiple imputation technique was applied.ResultsThe odds of poor academic performance declined with higher Internet use for academic purposes, but Internet use for entertainment increased the probability of being in the poor academic performance. College students who spent more time studying on college work were less likely to have poor academic performance.DiscussionThis study identified the factors (Internet use and study time) associated with academic performance among Chinese college students during the COVID-19 pandemic. These results can be used to design policies to improve educational outcomes and to address educational inequalities.

Abstract The corpse plant (Amorphophallus titanum) is so named because it produces a pungent, foul odor when flowering. Little is known about how the emitted volatiles change throughout the two-day flowering period. In this study, the comprehensive monitoring of the presence and change in volatile molecules during the female and the male flowering phases of A. titanum was conducted, and the plant temperature was monitored. A total of 422 volatile features were detected over the entire sampling period, of which 118 features were statistically significantly different between the pre-flowering and both flowering phases, and an additional 304 features were found present throughout the flowering period. A total of 45 molecules could be assigned putative names. The volatile profile of A. titanum changes over the two-day flowering period, with the S-containing molecules and aldehydes dominant in the female flowering phase, and the alcohols and hydrocarbons dominant in the male flowering phase. The two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) enabled us to identify 32 new molecules produced by A. titanum. Each of these molecules alone, and in combination, likely contribute to the different odors emitted during the flowering phase of A. titanum.

Abstract Background Necrotizing enterocolitis (NEC) is a disastrous gastrointestinal disease of newborns, and the mortality rate of infants with NEC is approximately 20%-30%. The exploration of pathogenic targets of NEC will be conducive to timely diagnosis of NEC. Methods The whole transcriptome RNA sequencing was performed on NEC samples to reveal the expression of lncRNAs, circRNAs, miRNAs and mRNAs. Using differential expression analysis, cross analysis, target prediction, enrichment analysis, the pathogenic ceRNA network and target was found. Results Preliminarily, 281 DEmRNAs, 21 DEmiRNAs, 253 DElncRNAs and 207 DEcircRNAs were identified in NEC samples compared with controls. After target prediction and cross analyses, a key ceRNA regulatory network was built including 2 lncRNAs, 4 circRNAs, 2 miRNAs and 20 mRNAs. These 20 mRNAs were significantly enriched in many carbohydrate metabolism related pathways. After cross analysis of hypoxia-, carbohydrate metabolism-related genes, and 20 core genes, one gene HK2 was finally obtained. Dendritic cells activated were significantly differentially infiltrated and negatively correlated with HK2 expression in NEC samples. Conclusions The promising pathogenic hypoxia-related gene HK2 has been firstly identified in NEC, which might also involve in the carbohydrate metabolism in NEC.

Abstract Background Septic shock is the most severe complication of sepsis, and is a major cause of childhood mortality, constituting a heavy public health burden. Methods We analyzed the gene expression profiles of septic shock and control samples from the Gene Expression Omnibus (GEO). Four differentially expressed genes (DEGs) from survivor and control groups, non-survivor and control groups, and survivor and non-survivor groups were selected. We used data about these genes to establish a logistic regression model for predicting the survival of septic shock patients. Results Leave-one-out cross validation and receiver operating characteristic (ROC) analysis indicated that this model had good accuracy. Differential expression and Gene Set Enrichment Analysis (GSEA) between septic shock patients stratified by prediction score indicated that the systemic lupus erythematosus pathway was activated, while the limonene and pinene degradation pathways were inactivated in the high score group. Conclusions Our study provides a novel approach for the prediction of the severity of pathology in septic shock patients, which are significant for personalized treatment as well as prognostic assessment.

Phosphatidylinositol-4-kinase alpha (PI4KIIIα), encoded by the PI4KA gene, can synthesize phosphatidylinositol-4-phosphate (PI-4-P), which serves as a specific membrane marker and is instrumental in signal transduction. PI4KA mutations can cause autosomal recessive diseases involving neurological, intestinal, and immunological conditions (OMIM:619621, 616531, 619708). We detected sepsis, severe diarrhea, and decreased immunoglobulin levels in one neonate. Two novel compound heterozygous mutations, c.5846T>C (p.Leu1949Pro) and c.3453C>T (p.Gly1151=), were identified in the neonate from the father and the mother, respectively. Sanger sequencing and reverse transcription polymerase chain reaction (RT-PCR) for peripheral blood and minigene splicing assays showed a deletion of five bases (GTGAG) with the c.3453C>T variant at the mRNA level, which could result in a truncated protein (p.Gly1151GlyfsTer17). The missense mutation c.5846T>C (p.Leu1949Pro) kinase activity was measured, and little or no catalytic activity was detected. According to the clinical characteristics and gene mutations with functional verification, our pediatricians diagnosed the child with a combined immunodeficiency and intestinal disorder close to gastrointestinal defects and immunodeficiency syndrome 2 (GIDID2; OMIM: 619708). Medicines such as immunomodulators are prescribed to balance immune dysregulation. This study is the first report of a synonymous mutation in the PI4KA gene that influences alternative splicing. Our findings expand the mutation spectrum leading to PI4KIIIa deficiency-related diseases and provide exact information for genetic counseling.

IntroductionThe high co-occurrence of tobacco smoking and depression is a major public health concern during the novel coronavirus disease-2019 pandemic. However, no studies have dealt with missing values when assessing depression. Therefore, the present study aimed to examine the effect of tobacco smoking on depressive symptoms using a multiple imputation technique.MethodsThis research was a longitudinal study using data from four waves of the China Health and Retirement Longitudinal Study conducted between 2011 and 2018, and the final sample consisted of 74,381 observations across all four waves of data collection. The present study employed a multiple imputation technique to deal with missing values, and a fixed effects logistic regression model was used for the analysis.ResultsThe results of fixed effects logistic regression showed that heavy smokers had 20% higher odds of suffering from depressive symptoms than those who never smoked. Compared to those who never smoked, for short-term and moderate-term quitters, the odds of suffering from depressive symptoms increased by 30% and 22%, respectively. The magnitudes of the odds ratios for of the variables short-term quitters, moderate-term quitters, and long-term quitters decreased in absolute terms with increasing time-gaps since quitting. The sub-group analysis for men and women found that heavy male smokers, short-term and moderate-term male quitters had higher odds of suffering from depressive symptoms than those who never smoked. However, associations between smoking status and depressive symptoms were not significant for women.ConclusionsThe empirical findings suggested that among Chinese middle-aged and older adults, heavy smokers and short-term and moderate-term quitters have increased odds of suffering from depressive symptoms than those who never smoked. Moreover, former smokers reported that the probability of having depressive symptoms decreased with a longer duration since quitting. Nevertheless, the association between depressive symptoms and smoking among Chinese middle-aged and older adults is not straightforward and may vary according to gender. These results may have important implications that support the government in allocating more resources to smoking cessation programs to help middle-aged and older smokers, particularly in men.

Abstract Pediatric tuberculosis (TB) remains a global health crisis. Despite progress, pediatric patients remain difficult to diagnose, with approximately half of all childhood TB patients lacking bacterial confirmation. In this pilot study (n = 31), we identify a 4-compound breathprint and subsequent machine learning model that accurately classifies children with confirmed TB (n = 10) from children with another lower respiratory tract infection (LRTI) (n = 10) with a sensitivity of 80% and specificity of 100% observed across cross validation folds. Importantly, we demonstrate that the breathprint identified an additional nine of eleven patients who had unconfirmed clinical TB and whose symptoms improved while treated for TB. While more work is necessary to validate the utility of using patient breath to diagnose pediatric TB, it shows promise as a triage instrument or paired as part of an aggregate diagnostic scheme.

This paper investigated the relationship between cultural distance, classroom silence, and the performance of culturally responsive and inclusive education (CRIE) using a survey of 1051 college students in Shanghai in 2022. We found a significantly positive association between migrant students’ cultural distance and their perceived learning gains in class. Students’ cultural distance increased their classroom silence as a form of protection but had no significant effect on their classroom silence as a sign of power. The classroom silence as protection decreased students’ perceived learning gains. However, classroom silence as power could be used by both local and migrant students as a hold-up strategy to strengthen their influence in class discussions, which could improve their perceived learning gains. Teachers’ CRIE played the most important role in migrant students’ perceived learning gains, while the effectiveness of CRIE was also actually dependent on the different channels and mechanisms of cultural distance and classroom silence. A cautious identification of classroom silence will improve the effectiveness of CRIE. Suggestions are offered to lighten the practice of educators, administrators, and instructors who face classroom silence from subnational migrant students.

Abstract Background Our objective was to study the phenotype of and molecular genetic mechanisms underlying congenital protein C (PC) deficiency in Chinese neonates. We report the case of a neonate who presented 4 h after birth with purpura fulminans of the skin and thrombosis in the kidney. We also carried out a through literature review to study the genotype and phenotype, relevance, diagnosis, management, and prognosis of neonates with congenital PC deficiency in China. Case presentation and literature review Following a septic work-up and check of PC and protein S (PS) levels that showed PC deficiency, we investigated the patient’s and her parents’ genotypes. Our patient was found to have a plasma PC level of 0.8%. Molecular testing revealed a compound heterozygous mutation of the PROC gene: From the father, a c._262 G > T p. ASP88Tyr mutation in exon 4; from the mother, a C. 400 + 5G mutation in intron 5 that had been previously reported as likely pathogenic. Both parents were found to have heterozygous mutations for PC deficiency. In China, 5 other cases of congenital PC deficiency in the neonatal period were reported in the literature. In those cases, purpura fulminans and thrombosis were the main symptoms, and homozygous or compound heterozygous mutations of the PROC gene were identified. Conclusion Congenital PC deficiency should be ruled out for neonates presenting with purpura fulminans and thrombosis.

The ground-airborne frequency-domain electromagnetic (GAFDEM) survey is a fast method to detect the deep underground structure in areas with difficult access. However, the suspended coil sensor in the survey system experiences attitude changes, which inevitably yield attitude error on the measured magnetic field and result in false apparent resistivity imaging. Due to the separated system structure, the attitude error in GAFDEM survey is significantly different from that in traditional airborne helicopter frequency-domain electromagnetic survey. In order to improve the detection accuracy, a modified iterative algorithm is proposed to suppress the attitude error for apparent resistivity imaging. Both simulation and practical experiment are conducted to verify the usefulness of the correction method. The simulation results indicate that the correction procedure is important and effective to reduce the attitude error in layered earth model. The field experiment results show that the corrected apparent resistivity imaging section is more consistent with the high-density resistivity topography and more reasonable than the uncorrected apparent resistivity imaging result obtained by conventional method. Consequently, the proposed suppression approach can reduce the attitude error to obtain more accurate apparent resistivity imaging results in GAFDEM survey, which may effectively promote the developments and applications of GAFDEM method and systems.

Objective To assess the rural–urban disparity in caesarean section rates using electronic health records from hospitals located in the Province of Inner Mongolia, which is a minority area in Northeastern China. Methods The study examined the electronic health records of women that gave birth in three major public hospitals between January 2012 and December 2016. Multinomial regression analyses were used to estimate rural–urban disparities in caesarean section rates. Results Data from 61 903 women were examined. Caesarean section rates increased slightly over the study period and the rate was significantly higher in rural compared with urban hospitals (48% versus 38%). This disparity consistently increased over time. Multinomial regression analyses showed that maternal age, ethnicity, health insurance type, employment status, reproductive history and the newborn’s sex were significant risk factors associated with caesarean section rate. Furthermore, stratified analysis of first-time pregnancies, minorities and different age groups showed that the odds of undergoing an emergency caesarean section was lower in the rural hospital, but the odds of undergoing a planned caesarean section was higher in the rural hospital. Conclusions Caesarean section rates have increased in rural areas and the disparity in rural–urban areas has increased substantially over the years.

Mastocytosis is an accumulation of clonal mast cells within tissues and it is most commonly caused by an activating mutation in the KIT gene. In this study, we report a neonatal case who presented with diffuse cutaneous mastocytosis (CM) at birth. In China, nine other cases of neonatal-onset CM have been reported in the literature since 2006. In those cases, diffuse CM and urticaria pigmentosa were the main symptoms, and mutations in exon 17 at codon 816 in KIT were identified.

The present study was aimed at investigating the expression of metastasis-associated in colon cancer 1 (MACC1) in nasopharyngeal carcinoma (NPC), its relationship with β-catenin, Met expression and the clinicopathological features of NPC, and its roles in carcinogenesis of NPC. Our results showed that MACC1 expression was higher in NPC cells and tissues than that in normal nasopharyngeal cells and chronic inflammation of the nasopharynx tissues, respectively. MACC1 expression was closely related to the clinical stage (p = 0.005) and the N classification (p

Although electromagnetic methods have made significant advances in archaeological exploration, there remains a lack of a method that offers both high operating efficiency and high resolution. This study introduces a novel approach derived from the Controlled Source Radio Magnetotelluric (CSRMT) method. The CSRMT method combines the efficient configuration of the Controlled Source Audio-magnetotelluric (CSAMT) method with enhanced resolution capabilities. To evaluate the efficacy of the new method in archeological exploration, we designed a series of models based on existing references related to ancient city wall remains. Using the 3D contraction integral equation method, we numerically simulated the high-frequency component of the CSRMT method, and then on, the Laterally Constrained Inversion technique is used to invert the data. The effectiveness of the method was assessed qualitatively and quantitatively through analysing the electromagnetic field and apparent resistivity of models with varying widths, heights, top burial depths, and resistivity. Our analysis revealed that models with shallower burial depth and greater height of the underground city wall exhibited higher resolution. The findings demonstrate that the CSRMT method can efficiently and accurately identify buried remains, making it a highly promising tool for archaeological exploration and warranting further development. [ABSTRACT FROM AUTHOR]

This article presents damping modification factors (DMFs) for the horizontal component of the strong-motion records generated by the shallow crustal and upper-mantle earthquakes in Japan. This model can be used to scale a 5% damped design spectrum that does not associate with a known magnitude and rupture distance to obtain a design spectrum with the desirable damping ratios. Our previous study suggested that the site effect on DMF was significant, and we used site class as the site-effect parameter. We used a quadratic function of damping ratio in a natural logarithm scale to model the effect of damping ratios and we used fourth-order polynomials of the natural logarithm spectral period to present the effect of the spectral period when the spectral period is over 0.06 s. The between-event, between-site, and within-site standard deviations can be described by the linear function of the damping ratio in a natural logarithm scale. The between-event standard deviations are smaller than the within-event standard deviations and the between-site standard deviations are less than the within-site ones at many spectral periods. Reasonable displacement spectra can be obtained by using the DMF model from this study to scale the 5% damped displacement spectra. The differences in the DMF values from the three types of earthquakes are moderate at many spectral periods and the predicted DMF values from this study are similar to those from other studies at some spectral periods, but the differences are considerable at the other spectral periods. The variation trend of the DMF values suggests that the predicted DMF values may reach the theoretic value of 1.0 at some spectral periods over 5.0 s. Residual distribution analysis suggested that the bilinear function of magnitude and fault-top depth can be used in a model for scenario earthquakes. [ABSTRACT FROM AUTHOR]

We present a set of ground-motion prediction equations for the horizontal components of the strong-motion records from shallow-crustal and upper-mantle earthquakes in Japan. We used a reasonably large dataset from earthquakes with a moment magnitude (Mw) over 4.9 and a reliable earthquake category determined by the tectonic location of earthquakes up to the end of 2012. The modeling of source and site effects in this study is similar to that by Zhao, Zhou, et al. (2016); a two-segmented model for the magnitude scaling function hinged at Mw 7.1 and site-period-based site classes were used as the site effect proxy that accounts for the effect of the nonlinear soil response. We used two types of multisegmented geometric attenuation functions with the distance break points based on the distributions of within-event residuals versus source distance. We found that the geometric attenuation functions with three distance break points (70, 130, and 220 km) for the shallow-crustal earthquakes and with two distance break points (90 and 150 km) for the upper-mantle events improved the model performance significantly. The first two break points for the shallow-crustal events are similar to those for the attenuation of the Fourier spectrum due to Moho reflection, but the corresponding coefficients between these spectra differ significantly. For the upper-mantle events, the geometric attenuation coefficient is somewhat surprisingly close to -1.0 for the first segment, 0.0 for the second segment, and -0.5 for the third segment at many periods, because these values are close to the classic attenuation rates of the Fourier spectrum for shallow-crustal events but having different distance break points. Moho reflection is not usually present in the ground motions from deep events, and we can only provide a plausible explanation; a future study is warranted for a theoretical explanation. [ABSTRACT FROM AUTHOR]

Aquaporin-9 (AQP9) is an aquaglyceroporin that biophysically conducts water, glycerol, and other small solutes. AQP9 is expressed in hepatocytes on the sinusoidal surfaces of hepatocyte plates in the liver, where it is considered responsible for the glycerol uptake in gluconeogenesis. However, limited information is available on the expression and regulating mechanism of AQP9 in different hyperglycemia models. Thus, this study examined the expression patterns of AQP9 and mitogen-activated protein kinase (MAPK) in Types 1 and 2 diabetes mellitus (DM) to clarify the roles and regulating mechanism of AQP9 in gluconeogenesis. Compared with the control group, the AQP9 expression significantly increased in both Types 1 and 2 DM, and the increased expression was associated with the activation of phosphorylated JNK (p-JNK) and the inhibition of phosphorylated p38 (p-p38). By contrast, phosphorylated ERK remained stable in the liver with Type 1 or 2 DM. These effects could be reversed by insulin treatment. That is, insulin downregulated AQP9 by inhibiting p-JNK and activating p-p38. The upregulation of AQP9 could be involved in gluconeogenesis and co-regulated by the JNK and p38 MAPK pathway in both Types 1 and 2 DM. [ABSTRACT FROM AUTHOR]

Multi-source and multi-frequency emission method can make full use of the valuable and short flight time in frequency domain semi-airborne electromagnetic (FSAEM) exploration, which has potential to investigate the deep earth structure in complex terrain region. Because several sources are adjacent in multi-source emission method, the interaction of different sources should be considered carefully. An equivalent circuit model of dual-source is established in this paper to assess the interaction between two individual sources, where the parameters are given with the typical values based on the practical instrument system and its application. By simulating the output current of two sources in different cases, the influence from the adjacent source is observed clearly. The current waveforms show that the mutual resistance causes the fluctuation and drift in another source and that the mutual inductance causes transient peaks. A field test with dual-source was conducted to certify the existence of interaction between adjacent sources. The simulation of output current also shows that current errors at low frequency are mainly caused by the mutual resistance while those at high frequency are mainly due to the mutual inductance. Increasing the distance between neighboring sources is a proposed measure to reduce the emission signal errors with designed ones. The feasible distance is discussed in the end. This study gives a useful guidance to lay multi sources to meet the requirement of measurement accuracy in FSAEM survey. [ABSTRACT FROM AUTHOR]

Purpose To investigate p53 and hepatoma-derived growth factor (HDGF) expression and their association with clinicopathological features of Ewing family tumour (EFT). Experimental design A total of 108 cases of EFT were retrospectively analysed. p53 and HDGF expression were detected using immunohistochemistry, and the relationships between p53 expression and HDGF expression and clinicopathological features of EFT were analysed. Kaplan-Meier curves were applied to estimate overall survival, log-rank test was used to assess prognostic relevance of p53 expression with overall survival and Cox regression model was performed to evaluate HRs. Results p53 expression and high HDGF expression was found in 17 (15.7%) and 55 (50.9%) patients, respectively. p53 expression was significantly associated with metastatic stage at initial diagnosis (p=0.007) and tumour venous/nerve invasion (p=0.023). A significant positive correlation was found between p53 expression and HDGF expression in EFT (p=0.022). p53 expression was an independent prognostic factor for overall survival of patients with EFT ( p<0.001). Patients with p53- positive/high HDGF expression had a significantly shorter overall survival than those with p53-positive/low HDGF expression or p53-negative/high HDGF expression or p53-negative/low HDGF expression. We first constructed a novel molecular staging system by combining p53 expression and HDGF expression, which significantly improved prognostic stratification for patients with EFT. Conclusions p53 expression was an independent prognostic factor for patients with EFT. Combining p53 expression and HDGF expression significantly improved prognostic stratification for patients with EFT. [ABSTRACT FROM AUTHOR]

Electron transport driven by a temperature gradient in a transport junction constructed by connecting a zigzag hexagonal boron nitride (h-BN) nanoribbon between two graphene nanoribbons (Gr/BN/Gr) is studied by density functional calculations and non-equilibrium Green’s function method. When the zigzag-edged graphene nanoribbons are in the ferromagnetic configuration, the BN barrier introduces a spin-dependent scattering and causes an ‘X’-type spin-dependent transmission functions around the Fermi level at equilibrium. In a linear response approximation, this gives rise to a Seebeck thermopower with opposite signs for different spins. It drives electrons with different spins to flow in opposite directions under a finite temperature gradient. Calculations show that the charge current is zero while spin current is not, thus pure spin current is generated. These findings suggests the great importance of BN barrier in the generation of thermal spin current using graphene and the idea should be taken into consideration in the design of spintronic devices using two dimensional materials. [ABSTRACT FROM AUTHOR]

Zigzag-edged graphene and h-BN nanoribbons with passivated edges in the ground state are either spin-degenerate or spin-unpolarized systems, which are not directly applicable for spin-polarized transport. In this work, based on density functional calculations, we demonstrate that the combination of them to form van der Waals (vdW) heterostructures can be adopted to realize fully spin polarized transport. As an example, the ballistic transport properties of a zigzag-edged graphene nanoribbon (ZGNR) with six zigzag carbon chains is studied first with each lead as a vdW heterostructure formed by attaching a h-BN monolayer to each side of the ZGNR with AA-stacking. A greatly decreased transmission gap (0.28 eV) in one spin and a greatly increased transmission gap (0.82 eV) in the other spin is achieved in the transmission function, resulting in fully spin polarized transport at low bias. This arises from the stagger potential imposed by the h-BN layers, which not only exists in the leads, but also extends to the channel region. It changes the energy of the edge states of different spins localized at different sublattices in an opposite way in the whole device. The transmission gap and the threshold voltage can be further modulated by applying a vertical pressure to the vdW leads to tune the strength of the stagger potential or simply by changing the ribbon width. Finally, the increase of the channel length will greatly reduce the magnitude of the transmission around the Fermi level and the transmission gap will eventually recover the value of the band gap of the pristine ZGNR. These findings not only provide a novel way for achieving fully spin polarized transport in graphene, but also demonstrate the great importance of vdW heterostructures in the design of spintronic devices. [ABSTRACT FROM AUTHOR]