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An ideal hydrogen storage material is a key topic in efficient hydrogen energy utilization. We have explored several potential hydrogen storage materials Mg 3 XH 8 (X = Ca, Sc, Ti, V, Cr, Mn) by first-principles calculations. The studied materials all belong to lightweight hydrogen storage materials. The normal phonon dispersion spectrum indicates, without regard to other materials, at least Mg 3 TiH 8 and Mg 3 VH 8 are completely stable in dynamics, which is also demonstrated by elastic stability criteria. The elastic properties show that they are all ductile materials with the applicable potential in flexible fields. Besides, they are gapless and metallic in band structures. With the correction of Hubbard values, all transition metal based Mg 3 XH 8 materials are magnetic materials with magnetic moments of 0.34 μ B for Mg 3 ScH 8 , and 2.14 μ B for Mg 3 TiH 8 , 1.29 μ B for Mg 3 TiH 8 , 2.65 μ B for Mg 3 TiH 8 and 4.86 μ B for Mg 3 MnH 8 , respectively. Whereas Mg 3 CrH 8 and Mg 3 MnH 8 exhibit highly light active in infrared and visible region. Considering overall structural stability, excellent mechanical properties, high gravimetric hydrogen density (6.21% and 6.07%) and moderate hydrogen desorption temperature (∼350 K), Mg 3 TiH 8 and Mg 3 VH 8 are considered as the candidates for promising hydrogen storage materials. Besides, Due to half-metallic nature, they are also potential in spin electronic devices. [Display omitted] • First-principles calculations to investigate Mg 3 XH 8 materials for hydrogen storage. • Mg 3 TiH 8 and Mg 3 VH 8 are found to be dynamically stable and ductile. • Mg 3 TiH 8 and Mg 3 VH 8 are half-metallic and promising in spin electronic devices. • Mg 3 TiH 8 and Mg 3 VH 8 both possess high gravimetric hydrogen density (>6.0%). • The hydrogen desorption temperatures of Mg 3 TiH 8 and Mg 3 VH 8 are around 350 K. [ABSTRACT FROM AUTHOR]

In order to search for good hydrogen storage materials, the structural, optoelectronic and hydrogen storage properties of double perovskites KNaMg 2 F 6-x H x and KNaAe 2 H 6 (Ae = Be, Mg, Ca) have been studied by first-principles calculations based on density functional theory in this paper. All the negative formation energies demonstrate the thermodynamic stability of these materials. Except for KNaBe 2 H 6 , the rest of the materials are wide-band gap semiconductors or insulators. The gravimetric storage capacity of KNaMg 2 F 6-x H x increases with the introduction of hydrogen and reaches a maximum of 5.19 wt% at x = 6. Meanwhile, the KNaBe 2 H 6 exhibits the best storage capacity of 8.57%. The favorable desorption temperature for stable KNaMg 2 H 6 material is 470.4 K, which is feasible in actual application. As the concentration of hydrogen increases, the electronic bandgap of KNaMg 2 F 6-x H x decreases gradually due to its electron conduction band moving to a lower energy range. The bond population analysis indicates that there is a mixture of ionic and covalent bonds in the studied materials. These materials are all ultraviolet absorber, and a red-shift can be observed in the absorption edge due to the variation of bandgap. • Double perovskites are introduced as the novel hydrogen storage materials. • Hydrogen substitution improves the stability and optoelectronic performance of double perovskites. • All materials exhibit wide band gaps as well as high ultraviolet absorption. • Stable KNaMg 2 H 6 material possesses ideal desorption temperature of 470.4 K and gravimetric storage capacity of 5.19 wt%. [ABSTRACT FROM AUTHOR]

Background: FXYD2, a gene coding for the γ subunit of Na+/K+-ATPase, was demonstrated to involve in carcinogenesis recently. However, the specific role of FXYD2 in clear cell renal cell carcinoma (ccRCC) remains unknown. The current study was conducted to investigate the expression, biological function, and potentially immune-related mechanisms of FXYD2 in ccRCC. Materials and methods. The data from TCGA-KIRC, ICGC, GEO, Oncomine, ArrayExpress, TIMER, HPA datasets, and our clinical samples were used to determine and validate the expression level, prognostic roles, and potentially immune-related mechanisms in ccRCC. Cell function assays were performed to investigate the biological role of FXYD2 in vitro.Results: FXYD2 was identified to be downregulated in ccRCC tissue compared to normal tissue, which was confirmed by our RT-PCR, WB, and IHC analyses. Kaplan-Meier survival analysis and Cox regression analysis suggested that downregulated FXYD2 could independently predict poor survival of ccRCC patients. Through the ESTIMATE algorithm, ssGSEA algorithm, CIBERSORT algorithm, TIMER database, and our laboratory experiment, FXYD2 was found to correlate with the immune landscape, especially regulatory T cells (Treg), in ccRCC. Gain-of-function experiment revealed that FXYD2 could restrain cell proliferation, migration, and invasion in vitro. Functional enrichment analysis illustrated that TGF-β-SMAD2/3, Notch, and PI3K-Akt-mTOR signaling pathways may be potential signaling pathways of FXYD2 in ccRCC.Conclusions: Downregulation of FXYD2 is associated with ccRCC tumorigenesis, poor prognosis, and increased Treg infiltration in ccRCC, which may be related to TGF-β-SMAD2/3, Notch, and PI3K-Akt-mTOR signaling pathways. This will probably provide a novel prognostic marker and potential therapeutic target for ccRCC. [ABSTRACT FROM AUTHOR]

The effect of lithium doping on novel double perovskite materials for hydrogen storage has been investigated through first-principles calculation. The lithium doping would cause phase change due to different crystal symmetry. Based on tolerance factors, cohesive energy and Born-Huang criteria, the materials are all stable. The analysis of hydrogen storage properties indicates that lithium doping can both improve the gravimetric storage capacity to 4.41% and 5.08%, and decrease the desorption temperature to 348.7 K and 325.0 K for K 2 LiScH 6 and K 2 LiAlH 6 , respectively. And to a certain extent, the introduction of lithium improves the optoelectronic properties especially the photoresponse in ultraviolet region, which demonstrates the applicable potential in photocatalysis. The results are consistent with the wide bandgap values. Our study provides some reference for further experimental studies of double perovskites in hydrogen storage materials. • Lithium is introduced into double perovskites to improve hydrogen storage characteristics. • These materials exhibit an optimal storage capacity of 5.08% and desorption temperature of 325.0 K. • The variations of accurate optoelectronic property are obtained by hybrid HSE06 functional. [ABSTRACT FROM AUTHOR]

Background: Clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney cancer whose incidence and mortality rate are increasing. Identifying immune-related lncRNAs and constructing a model would probably provide new insights into biomarkers and immunotherapy for ccRCC and aid in the prognosis prediction.Methods: The transcription profile and clinical information were obtained from The Cancer Genome Atlas (TCGA). Immune-related gene sets and transcription factor genes were downloaded from GSEA website and Cistrome database, respectively. Tumor samples were divided into the training set and the testing set. Immune-related differentially expressed lncRNAs (IDElncRNAs) were identified from the whole set. Univariate Cox regression, LASSO, and stepwise multivariate Cox regression were performed to screen out ideal prognostic IDElncRNAs (PIDElncRNAs) from the training set and develop a multi-lncRNA signature.Results: Consequently, AC012236.1, AC078778.1, AC078950.1, AC087318.1, and AC092535.4 were screened to be significantly related to the prognosis of ccRCC patients, which were used to establish the five-lncRNA signature. Its wide diagnostic capacity was revealed in different subgroups of clinical parameters. Then AJCC-stage, Fuhrman-grade, pharmaceutical, age, and risk score regarded as independent prognostic factors were integrated to construct a nomogram, whose good performance in predicting 3-, 5-, and 7-year overall survival of ccRCC patients was revealed by time-dependent ROC curves and verified by the testing sets and ICGC dataset. The calibration plots showed great agreement of the nomogram between predicted and observed outcomes. Functional enrichment analysis showed the signature and each lncRNA were mainly enriched in pathways associated with regulation of immune response. Several kinds of tumor-infiltrating immune cells like regulatory T cells, T follicular helper cells, CD8+ T cells, resting mast cells, and naïve B cells were significantly correlated with the signature.Conclusion: Therefore, we constructed a five-lncRNA model integrating clinical parameters to help predict the prognosis of ccRCC patients. The five immune-related lncRNAs could potentially be therapeutic targets for immunotherapy in ccRCC in the future. [ABSTRACT FROM AUTHOR]

In alkali metal‐doped optical temperature measurement materials, the influence of the electronegativity difference of alkali metal ions on optical temperature measurement performance is rarely reported. This study investigates and analyzes the performance of optical temperature measurement of Na0.5Gd0.5TiO3: Yb, Er doped with Li+ and K+ ions, utilizing the Judd‐Ofelt theory and the first‐principles method. The results reveal that the sensitivities increase with the increase of atomic number of doped alkali metal ions. The reason is that a difference in ionic radius between the dopant and the replaced ion decreases the symmetry of the crystal field and increases the value of Ω2. The doping K+ with low electronegativity leads to an increase in the s orbital electron density of rare earth ions, thereby repelling the d orbital electrons, reducing the d electron density, and decreasing the value of Ω6. Based on the Judd‐Ofelt theory, a combination of a large Ω2 and a small Ω6 is expected to enhance the absolute sensitivity of optical temperature‐measuring materials doped with rare earth ions. Therefore, it can be concluded that doping an ion with low electronegativity and a significant radius difference from the substitution site is beneficial for enhancing the optical temperature sensitivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Ba 6 CCh 4 (Ch = S, Se, Te) are stable materials with hexagonal structures. • The Ba 6 CCh 4 (Ch = S, Se, Te) anti-perovskites have direct band structures. • The materials have high light absorption coefficients in UV–Vis-IR region. The structural, electronic and optical properties of anti-perovskites Ba 6 CCh 4 (Ch = S, Se, Te) are investigated by first-principles calculations. The perovskites are stable hexagonal materials because of negative formation energy and positive phonon spectra. The materials have brittle characteristics from elastic properties. Besides, the elastic Born-Huang stability criteria confirm the structure stability. They are direct band perovskites with bandgap values of 1.554 eV, 1.311 eV and 1.517 eV for Ba 6 CS 4 , Ba 6 CSe 4 and Ba 6 CTe 4 , respectively. The VBM is composed mainly by C-p and Ba-d states, while and CBM is due to contributions of Ba-d states. The chalcogen elements have little contribution to both conduction and valence bands. The high light absorption in UV–Vis-IR region compared with AM1.5 irradiance confirm the great prospects in solar energy utilization including photovoltaic. [ABSTRACT FROM AUTHOR]

Acute rejection (AR) after kidney transplant is one of the major obstacles to obtain ideal graft survival. Reliable molecular biomarkers for AR and renal allograft loss are lacking. This study was performed to identify novel long noncoding RNAs (lncRNAs) for diagnosing AR and predicting the risk of graft loss. The several microarray datasets with AR and nonrejection specimens of renal allograft downloaded from Gene Expression Omnibus database were analyzed to screen differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs). Univariate and multivariate Cox regression analyses were used to identify optimal prognosis-related DElncRNAs for constructing a risk score model. 39 common DElncRNAs and 185 common DEmRNAs were identified to construct a lncRNA-mRNA regulatory relationship network. DElncRNAs were revealed to regulate immune cell activation and proliferation. Then, 4 optimal DElncRNAs, ATP1A1-AS1, CTD-3080P12.3, EMX2OS, and LINC00645, were selected from 17 prognostic DElncRNAs to establish the 4-lncRNA risk score model. In the training set, the high-risk patients were more inclined to graft loss than the low-risk patients. Time-dependent receiver operating characteristics analysis revealed the model had good sensitivity and specificity in prediction of 1-, 2-, and 3-year graft survival after biopsy (AUC = 0.891, 0.836, and 0.733, respectively). The internal testing set verified the result well. Gene set enrichment analysis which expounded NOD-like receptor, the Toll-like receptor signaling pathways, and other else playing important role in immune response was enriched by the 4 lncRNAs. Allograft-infiltrating immune cells analysis elucidated the expression of 4 lncRNAs correlated with gamma delta T cells and eosinophils, etc. Our study identified 4 novel lncRNAs as potential biomarkers for AR of renal allograft and constructed a lncRNA-based model for predicting the risk of graft loss, which would provide new insights into mechanisms of AR. [ABSTRACT FROM AUTHOR]

The joint analysis of spatial and temporal processes poses computational challenges due to the data's high dimensionality. Furthermore, such data are commonly non‐Gaussian. In this paper, we introduce a copula‐based spatiotemporal model for analyzing spatiotemporal data and propose a semiparametric estimator. The proposed algorithm is computationally simple, since it models the marginal distribution and the spatiotemporal dependence separately. Instead of assuming a parametric distribution, the proposed method models the marginal distributions nonparametrically and thus offers more flexibility. The method also provides a convenient way to construct both point and interval predictions at new times and locations, based on the estimated conditional quantiles. Through a simulation study and an analysis of wind speeds observed along the border between Oregon and Washington, we show that our method produces more accurate point and interval predictions for skewed data than those based on normality assumptions. [ABSTRACT FROM AUTHOR]

The analysis of time series data with detection limits is challenging due to the high‐dimensional integral involved in the likelihood. Existing methods are either computationally demanding or rely on restrictive parametric distributional assumptions. We propose a semiparametric approach, where the temporal dependence is captured by parametric copula, while the marginal distribution is estimated non‐parametrically. Utilizing the properties of copulas, we develop a new copula‐based sequential sampling algorithm, which provides a convenient way to calculate the censored likelihood. Even without full parametric distributional assumptions, the proposed method still allows us to efficiently compute the conditional quantiles of the censored response at a future time point, and thus construct both point and interval predictions. We establish the asymptotic properties of the proposed pseudo maximum likelihood estimator, and demonstrate through simulation and the analysis of a water quality data that the proposed method is more flexible and leads to more accurate predictions than Gaussian‐based methods for non‐normal data. The Canadian Journal of Statistics 47: 438–454; 2019 © 2019 Statistical Society of Canada [ABSTRACT FROM AUTHOR]

The physical properties of three potential colbat-containing perovskites are studied through first principles calculation. The structural analysis reveals that the Cs 2 InCoI 6 and Cs 2 AgCoI 6 are ductile and potential in flexible devices. The negative formation energies indicate that all these perovskite syntheses are practicable in experiment. However, the results of tolerance factors and phonon spectra are presented against the structural dynamic stability of pure cubic phase of Cs 2 TlCoI 6 and Cs 2 AgCoI 6 and there may be lattice distortion. The band gaps of Cs 2 InCoI 6 , Cs 2 TlCoI 6 and Cs 2 AgCoI 6 are 0.833 eV, 1.713 eV and 0.783 eV, respectively, all values are within the ideal range for semiconductors that applied in optoelectronic devices. They all exhibit broad-spectrum light absorption in ultraviolet and visible region, and the absorption coefficient of Cs 2 InCoI 6 even maintains a value above 10000 cm−1 at wavelength of 1400 nm. Among them, Cs 2 InCoI 6 perovskite has direct band structure, smaller carrier effective mass than that of CsPbI 3 and broad solar absorption characteristics, which is considered as a promising candidate material for optoelectronic devices. • The physical properties of three novel cobalt perovskites are studied. • Cs 2 TlCoI 6 is found to be stable in tetragonal rather than cubic phase thus a phase transition may take place. • Cubic Cs 2 InCoI 6 is found to be a stable perovskite with broadband light absorption. • Pressure-induced optical properties and structural stabilities of Cs2InCoI6 are studied. [ABSTRACT FROM AUTHOR]

We propose a new estimation method to estimate the nonparametric functions in additive models, where the response is subject to fixed censoring. Under some regularity conditions, we show that the proposed estimator is uniformly consistent with certain convergence rates. The simulation study shows that the proposed estimator performs well in finite sample sizes. We also analyze a dataset from an HIV study for an illustration. [ABSTRACT FROM AUTHOR]

Abstract: We propose a semiparametric estimator for single‐index models with censored responses due to detection limits. In the presence of left censoring, the mean function cannot be identified without any parametric distributional assumptions, but the quantile function is still identifiable at upper quantile levels. To avoid parametric distributional assumption, we propose to fit censored quantile regression and combine information across quantile levels to estimate the unknown smooth link function and the index parameter. Under some regularity conditions, we show that the estimated link function achieves the non‐parametric optimal convergence rate, and the estimated index parameter is asymptotically normal. The simulation study shows that the proposed estimator is competitive with the omniscient least squares estimator based on the latent uncensored responses for data with normal errors but much more efficient for heavy‐tailed data under light and moderate censoring. The practical value of the proposed method is demonstrated through the analysis of a human immunodeficiency virus antibody data set. [ABSTRACT FROM AUTHOR]

Motivated by a genome‐wide association study on the glomerular filtration rate, we develop a new robust test for longitudinal data to detect the effects of biomarkers in high‐dimensional quantile regression, in the presence of prespecified control variables. The test is based on the sum of score‐type statistics deduced from conditional quantile regression. The test statistic is constructed in a working‐independent manner, but the calibration reflects the intrinsic within‐subject correlation. Therefore, the test takes advantage of the feature of longitudinal data and provides more information than those based on only one measurement for each subject. Asymptotic properties of the proposed test statistic are established under both the null and local alternative hypotheses. Simulation studies show that the proposed test can control the family‐wise error rate well, while providing competitive power. The proposed method is applied to the motivating glomerular filtration rate data to test the overall significance of a large number of candidate single‐nucleotide polymorphisms that are possibly associated with the Type 1 diabetes, conditioning on the patients' demographics. [ABSTRACT FROM AUTHOR]

Pyroptosis is a kind of programmed cell death triggered by the inflammasome. Growing evidence has revealed the crucial utility of pyroptosis in tumors. However, the potential mechanism of pyroptosis in clear cell renal cell carcinoma (ccRCC) is still unclear. In this research, we systematically analyze the genetic and transcriptional alterations of pyroptosis-related genes (PRGs) in ccRCC, identify pyroptosis-related subtypes, analyze the clinical and microenvironmental differences among different subtypes, develop a corresponding prognostic model to predict the prognosis of patients, and interpret the effect of pyroptosis on ccRCC microenvironment. This study provides a new perspective for a comprehensive understanding of the role of pyroptosis in ccRCC and its impact on the immune microenvironment, and a reliable scoring system was established to predict patients' prognosis. [ABSTRACT FROM AUTHOR]

Researchers sometimes have a priori information on the relative importance of predictors that can be used to screen out covariates. An important question is whether any of the discarded covariates have predictive power when the most relevant predictors are included in the model. We consider testing whether any discarded covariate is significant conditional on some prechosen covariates.We propose a maximum-type test statistic and show that it has a nonstandard asymptotic distribution, giving rise to the conditional adaptive resampling test. To accommodate signals of unknown sparsity, we develop a hybrid test statistic, which is a weighted average of maximum- and sum-type statistics.We prove the consistency of the test procedure under general assumptions and illustrate how it can be used as a stopping rule in forward regression.We show, through simulation, that the proposed method provides adequate control of the familywise error rate with competitive power for both sparse and dense signals, even in high-dimensional cases, and we demonstrate its advantages in cases where the covariates are heavily correlated.We illustrate the application of our method by analysing an expression quantitative trait locus dataset. [ABSTRACT FROM AUTHOR]

We investigate the energy band structure of nanoporous silicon thin film using first principles calculation based on density functional theory (DFT) with the generalized gradient approximation (GGA). The calculation results show that the band gaps of nanoporous silicon increase with increasing porosity, increase with decreasing the thickness of matrix layer, and almost independent of the thickness of pore layer. Moreover, the band structure of nanoporous silicon can be transformed from indirect to direct gap on thin films of (111) and (110) faces. It will be the guidance and reference for the fabrication of porous silicon optoelectronic devices. [ABSTRACT FROM AUTHOR]

Pyroptosis is a kind of programmed cell death triggered by the inflammasome. Growing evidence has revealed the crucial utility of pyroptosis in tumors. However, the potential mechanism of pyroptosis in clear cell renal cell carcinoma (ccRCC) is still unclear. In this research, we systematically analyze the genetic and transcriptional alterations of pyroptosis-related genes (PRGs) in ccRCC, identify pyroptosis-related subtypes, analyze the clinical and microenvironmental differences among different subtypes, develop a corresponding prognostic model to predict the prognosis of patients, and interpret the effect of pyroptosis on ccRCC microenvironment. This study provides a new perspective for a comprehensive understanding of the role of pyroptosis in ccRCC and its impact on the immune microenvironment, and a reliable scoring system was established to predict patients' prognosis. [ABSTRACT FROM AUTHOR]

The comparison study of arsenic-based double halide perovskite materials concentrated on the physical properties is initiated based on first principle. The structure stability is confirmed by the tolerance factor, formation energy and elastic constant. The materials are ductile and ionic compounds through elastic properties. The range of band gap is from 0.882eV to 2.125eV, close to the recommended values for optoelectronic and photovoltaic application. The halogen atoms have great effects on electronic band structures while alkali metal does rarely. All small effective masses for the studied materials indicate high mobilities, favorable for carrier transport. The excellent light absorption properties corresponding to ultraviolet–visible–infrared region reveal great applicable potential for solar energy utilization. Among these materials, K2AgAsBr 6 is the most suitable for use as a solar cell material and photocatalytic material because it has an ideal band gap value, high dielectric constant and good optical absorption properties. [Display omitted] • The arsenic-based double perovskite A 2 AgAsX 6 (A ​= ​K, Rb, Cs; X ​= ​Cl, Br, I) possess ideal band gaps from 0.882eV to 2.125eV. • Their high absorption coefficients, which correspond to the solar spectrum, indicate effective utilization of solar energy. • K 2 AgAsBr 6 is the best candidate for photovoltaic application among the studied materials. [ABSTRACT FROM AUTHOR]

In various applications with large spatial regions, the relationship between the response variable and the covariates is expected to exhibit complex spatial patterns. We propose a spatially clustered varying coefficient model, where the regression coefficients are allowed to vary smoothly within each cluster but change abruptly across the boundaries of adjacent clusters, and we develop a unified approach for simultaneous coefficient estimation and cluster identification. The varying coefficients are approximated by penalized splines, and the clusters are identified through a fused concave penalty on differences in neighboring locations, where the spatial neighbors are specified by the minimum spanning tree (MST). The optimization is solved efficiently based on the alternating direction method of multipliers, using the sparsity structure from MST. Furthermore, we establish the oracle property of the proposed method considering the structure of MST. Numerical studies show that the proposed method can efficiently incorporate spatial neighborhood information and automatically detect possible spatially clustered patterns in the regression coefficients. An empirical study in oceanography illustrates that the proposed method is promising to provide informative results. [ABSTRACT FROM AUTHOR]

We propose a quantile regression framework to model accelerated life tests (ALT) data. The quantile of the failure time distribution at the usage level can be easily estimated using quantile regression. Compared with traditional parametric regression methods, quantile regression is distribution-free, efficient in the presence of censoring, and more flexible in modeling ALT relations. More importantly, we show that it is able to handle ALT data with a failure-free life, which is a great challenge in the ALT literature. We use extensive simulation studies and two real ALT case studies to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this article, we develop a new method of parametric estimation for process of Ornstein-Uhlenbeck type. The proposed method is based on GMM with a continuum of moment conditions (CGMM), which is introduced in Carrasco and Florens (2002), and the estimator is called the CGMM estimator. We show that this CGMM estimator has consistency and asymptotic normality. Simulation studies evidence that the proposed method performs quite well in small-sample cases. [ABSTRACT FROM PUBLISHER]

In quantile regression, it is of interest to determine whether a covariate has varying or constant effect across quantiles, since in situations where the quantile coefficients share some common features we can improve the estimation efficiency through joint modeling of multiple quantiles. To automatically perform estimation and detection of the interquantile commonality, we propose a new penalization procedure with two variations of interquantile penalties for censored quantile regression. The proposed methods are shown to be consistent in separating the constant and varying effects across quantiles, and the resulting slope estimators have the same asymptotic efficiency with the oracle estimators obtained as if the true interquantile model structure is known a priori . Our simulation study suggests that the proposed estimators have competitive or higher efficiency than the existing estimator obtained by fitting censored quantile regression at each quintile level separately. The practical value of the proposed methods is further illustrated through the analysis of a renal disease data. [ABSTRACT FROM AUTHOR]

In this paper, we consider two weighted estimators to improve estimation efficiency in quantile regression with longitudinal data. The first estimator is from weighted quantile regression, and the second estimator is from weighted composite quantile regression, where the weights in the second estimator are from the first estimator. Different from earlier literature, our weights are quantile adaptive, which borrow information from the intra-subject correlation of the conditional quantile scores, rather than the conditional least squares scores. The weight for each subject is obtained from smoothed empirical likelihood quantile estimator, where quadratic inference function method is used to model the inverse of the correlation matrix of the conditional quantile scores. Under some regularity conditions, we prove that the weighted estimators are more efficient than the standard quantile regression estimators with equal weights. We conduct a simulation study and a real data analysis to evaluate the performance of the proposed approach. [ABSTRACT FROM AUTHOR]

We propose composite quantile regression for dependent data, in which the errors are from short-range dependent and strictly stationary linear processes. Under some regularity conditions, we show that composite quantile estimator enjoys root- n consistency and asymptotic normality. We investigate the asymptotic relative efficiency of composite quantile estimator to both single-level quantile regression and least-squares regression. When the errors have finite variance, the relative efficiency of composite quantile estimator with respect to the least-squares estimator has a universal lower bound. Under some regularity conditions, the adaptive least absolute shrinkage and selection operator penalty leads to consistent variable selection, and the asymptotic distribution of the non-zero coefficient is the same as that of the counterparts obtained when the true model is known. We conduct a simulation study and a real data analysis to evaluate the performance of the proposed approach. [ABSTRACT FROM AUTHOR]

Query processing for trajectory data is a hot topic in the field of moving objects databases (MODs). Most of the previous research work focused on the Euclidean space, and the uncertain trajectories are represented as sheared cylinders. However, in many applications (e.g. traffic management), the movements of moving objects (MOs) are constrained by the road network environments, which makes the previous methods ineffective. In this paper, we firstly construct an uncertain trajectory model, which is composed of a sequence of segment units with earliest arrival time and latest departure time, based on the assuming availability of a maximum speed on each road segment. Secondly, we present a partition-based uncertain trajectory index (PUTI) to facilitate the search of possible MOs within the space and time range in the road networks based on the uncertain trajectory model. It provides appropriate groups to gather segment units of trajectories according to their network distances. Finally, an efficient algorithm for range query is proposed by leveraging the index. The experiments on two datasets demonstrate that the uncertain trajectory model is effective, and PUTI also significantly outperforms the network distance based MON-tree on range query. [ABSTRACT FROM AUTHOR]

Laser communication plays an important role in a broad range of fields. In need of the faster data rate of the flourished information communication, we propose a hybrid scheme that utilizes photon's polarization property integrated with on-off keying modulation to improve the data rate. The theoretical analysis indicates that this polarization property of photon is a useful dimension to combine with other schemes to obtain a higher performance, even in the heavy atmosphere turbulence, showing its potential in optic communication in the future. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we propose a two-stage variable selection procedure for high dimensional quantile varying coefficient models. The proposed method is based on basis function approximation and LASSO-type penalties. We show that the first stage penalized estimator with LASSO penalty reduces the model from ultra-high dimensional to a model that has size close to the true model, but contains the true model as a valid sub model. By applying adaptive LASSO penalty to the reduced model, the second stage excludes the remained irrelevant covariates, leading to an estimator consistent in variable selection. A simulation study and the analysis of a real data demonstrate that the proposed method performs quite well in finite samples, with regard to dimension reduction and variable selection. [Copyright &y& Elsevier]

Abstract: Background: Since its introduction into North America in 1999, West Nile virus (WNV) has spread rapidly across United States (US). Objective: To genetically analyze WNV isolates from US blood donors during 2002–2005. Study design: Full-length nucleotide (NT) sequences of WNV isolates from 23 US volunteer blood donors of different geographic areas from 2002 to 2005 were determined and analyzed. Results: Results indicated an overall lack of geographic pattern to WNV in US. Analyses of the viral genetic diversity demonstrated that the WNV evolved at approximately five NT substitutions and 0.8 amino acid (AA) mutations per genome per year. Comparison of the functional sequences of WNV genome showed a higher evolution rate in the coding region than in the non-coding region. Furthermore, a greater diversity was observed in the nonstructural proteins as compared to the structural proteins. Sequence alignment analysis revealed that the rapid spread of WNV in US was accompanied by the establishment of a dominant genetic variant with 11 conserved NT mutations. Conclusions: The establishment of a dominant genotype across US and the displacement and possible extinction of earlier progenitor genotypes appears to have resulted from the accumulation and fixation of 11 nucleotide mutations throughout the coding region of WNV genome. [Copyright &y& Elsevier]

In this paper, we study the key factors that impact on power systems resilience under severe weather-induced disruptions from three dimensions: the extrinsic disruptions, the intrinsic capacities of a system and the effectiveness of recovery. Using 12 years of historical blackout data from 2007 to 2018 in the U.S., we apply various group selection and bi-level selection methods to identify the key predictor groups as well as factors within-group that affect power system resilience. After deleting the predictors which are fully or highly correlated with others, we split the remaining 39 candidate predictors into 8 natural groups and consider the number of customers affected and the recovery time as response variables. To ensure stability of the selection process, we adopt the random subsampling method to rank the importance of the groups and key predictors. It is found that the disruption types from the extrinsic disruptions dimension have a significant impact on the resilience of power systems, especially for the hurricanes with high scales. From the intrinsic capabilities dimension, the demographic group has a large impact on the number of customers affected. The number of customers affected tends to be large in highly urbanized areas with large population. From the effectiveness of recovery dimension, the group of economics is top selected for the recovery time. It is found that the power system tends to be more resilient with a better economic health. Feature selection under quantile regression is also conducted as the histograms show that the distributions of the responses are skewed and heavy-tailed. It is found that the recovery time is also greatly affected by the investment on the compliance and enforcement program from the North American Electric Reliability Corporation. In summary, our analysis provides interesting insights for understanding power system resilience and developing strategies to enhance the resilience. • Look into extrinsic disruptions, intrinsic capacities and effectiveness of recovery. • Analyse 12 years of historical blackout data from 2007 to 2018 in the U.S.. • Apply group selection and bi-level selection to identify key groups and predictors. • Use the random subsampling to rank the importance of the groups and predictors. • Provide insights for understanding and enhancing power system resilience. [ABSTRACT FROM AUTHOR]

Abstract: Background: Starting in 1999, the West Nile virus (WNV) epidemic represents the largest outbreak of arboviral encephalitis ever recorded in the U.S. The effective means to determine an infection are detection of viral nucleic acid and/or viral specific immunoglobulin, IgM and/or IgG. Objective: To develop a highly sensitive and specific TaqMan RT-PCR assay for the detection and quantification of WNV RNA of lineage 1 and lineage 2. Study design: A TaqMan RT-PCR primer–probe was designed to perfectly match target sequences of all sequenced WNV strains and isolates, which added a layer of protection against false-negative results due to strain variability. In addition, the inclusion of a low level RNA internal control (IC) in the assay increased the precision and accuracy of the assay. Results: By optimizing the RNA preparation procedure for increased WNV RNA recovery, together with optimizing the primer–probe and TaqMan conditions for improved amplification efficiency, we developed a highly sensitive assay with the detection limit of 10 copies/mL. To evaluate the assay, we tested plasma samples from 12 transfusion-transmitted implicated cases in 2002 and from 68 positive blood donors in 2003. All tested specimens were WNV positive. The viral load of 68 positive blood donor samples collected in 2003 ranged from 10 copies/mL to 67,000 copies/mL with a mean of 8100 copies/mL. Furthermore, high sensitivity of the assay was achieved without compromising specificity. All 100 routine donor samples tested negative. Conclusions: The assay results demonstrate that our in-house TaqMan RT-PCR procedure can detect and quantify WNV RNA of lineage1 and lineage 2 in human plasma with high sensitivity and specificity. [Copyright &y& Elsevier]

Perovskite solar cells have become the most promising third-generation solar cells because of their superior physical–chemical properties and high photoelectric conversion efficiency. However, the current obstacles to commercialization of perovskite solar cells are their poor stability and harmful elements. How to find high-efficiency, high-stability and non-toxic perovskite materials from thousands of possible perovskite crystals is the key to solve this problem. In this paper, the inorganic halide double perovskite A2BX6 and its crystal structure are considered, and the data mining algorithm in informatics is introduced into the high-throughput computing data to analyze various elements in nature to study the perovskite materials that can meet the requirements of high performance. The photoelectric conversion properties and stability of 42 inorganic double perovskite materials are studied based on density functional theory (DFT). The results show that the tolerance factors of 39 crystals are between 0.8 and 1.10, indicating that these crystals have stable perovskite structure. In addition, the dielectric function, PDOS, elastic modulus, shear modulus and poison's ratio of these crystals are analyzed. According to the above theoretical simulation results, three candidate materials for ideal light absorption are presented. This can provide a theoretical basis for the industrial application of perovskite solar cells. [ABSTRACT FROM AUTHOR]

Diabetes mellitus (DM) is a widespread metabolic disease presenting with various complications, including spermatogenic dysfunction. However, the underlying mechanisms are still unclear. Ferroptosis, a novel type of programmed cell death, is associated with much metabolic diseases. Here, we investigated the role of ferroptosis in spermatogenic dysfunction of streptozotocin (STZ)-induced type 1 diabetic mice (diabetic mice), high glucose (HG)-treated GC-2 cells (HG cells) as well as testicular tissues of diabetic patients. We found an accumulation of iron, elevated malondialdehyde level and reduced glutathione level in the testis tissues of diabetic mice and HG cells. Histological examination showed a decrease in spermatogenic cells and spermatids within the seminiferous tubules as well as mitochondrial shrinkage in the testis tissues of diabetic mice. Ferrostatin-1 (Fer-1), the inhibitor of ferroptosis, mitigated ferroptosis-associated iron overload, lipid peroxidation accumulation and spermatogenic dysfunction of diabetic mice. Furthermore, we observed a downregulation of GPX4, FTL and SLC7A11 in diabetic mice and HG cells. Fer-1 treatment and GPX4 overexpression counteracted the effects of HG on cell viability, reactive oxygen species, lipid peroxidation and glutathione via inhibition of ferroptosis. Moreover, we found an elevation of ferroptosis in testicular tissues of diabetic patients. Taken together, our results identify the crucial role of ferroptosis in diabetic spermatogenic dysfunction and ferroptosis may be a promising therapeutic target to improve spermatogenesis in diabetic patients. [Display omitted] • Increased ferroptosis caused spermatogenic dysfunction in type 1 diabetic mice and patients. • Ferrostatin-1 treatment alleviated spermatogenic dysfunction in diabetic mice. • Ferrostatin-1 treatment and GPX4 overexpression attenuated ferroptosis in high glucose treated GC-2 cells. • Inhibition of ferroptosis may be a potential therapy to alleviate diabetic male infertility. [ABSTRACT FROM AUTHOR]

The treatment of cancer has always been a challenging problem in the medical community. In this paper, based on density functional theory (DFT), B12N12 nanocage was studied as delivery carriers of sulforaphane (SF) anticancer drug, and the adsorption properties, electronic properties and topological analysis of complexes were calculated. The adsorption energy, solvation energy, electronic and topological properties were calculated by used M06-2X/6-311+G(2d,p), M05-2X/6-31G(p) and B3LYP/6-311G(d,p) theoretical levels, respectively. In addition, the effects of doping and packaging of alkaline earth metal (Be, Mg, Ca) on the related properties were also studied. Doping and packaging metal can improve the transfer characteristics of nanocages by changing the polarity of systems. All calculation results were performed in Gaussian 09 software. The frontier molecular orbital (FMO) and natural bond orbital (NBO) analysis showed that nanocages acting as charge acceptors and drugs as charge donors during the adsorption process. The atoms-in-molecules (AIM) and interaction region indicator (IRI) analysis showed that there were strong polar covalent bonds between drug and nanocages, which enabled drug to be stably adsorbed on nanocages. The solvation effect results showed that acidic conditions were more conducive to drug transport and release. Compared with the original and encapsulated systems, the doping system has better adsorption properties and solvation effect. Moreover, the charge transfer between drug and nanocages in doping system was more frequent and the interaction was stronger. Therefore, our results indicated that the doping nanocages MB11N12 (M = Be, Mg and Ca) were more suitable as the drug carrier system for SF anticancer drug. [ABSTRACT FROM AUTHOR]

Hidden Markov models are useful in simultaneously analyzing a longitudinal observation process and its dynamic transition. Existing hidden Markov models focus on mean regression for the longitudinal response. However, the tails of the response distribution are as important as the center in many substantive studies. We propose a quantile hidden Markov model to provide a systematic method to examine the entire conditional distribution of the response given the hidden state and potential covariates. Instead of considering homogeneous hidden Markov models, which assume that the probabilities of between-state transitions are independent of subject- and time-specific characteristics, we allow the transition probabilities to depend on exogenous covariates, thereby yielding nonhomogeneous Markov chains and making the proposed model more flexible than its homogeneous counterpart. We develop a Bayesian approach coupled with efficient Markov chain Monte Carlo methods for statistical inference. Simulations are conducted to assess the empirical performance of the proposed method. The proposed methodology is applied to a cocaine use study to provide new insights into the prevention of cocaine use. [ABSTRACT FROM AUTHOR]

[Display omitted] • The materials are stable double perovskites by tolerance factor and formation energy. • The studied materials are all direct and quasi-direct semiconductors. • Tl 2 PdBr 6 is regarded as a potential candidate for single junction solar absorber. The structural stability, energy band and photoelectric properties of vacancy- ordered double halide perovskites A 2 BX 6 (A = In, Tl; B = Pd, Pt; X = Cl, Br, I) are studied in detail by first principles in this paper. The results show that these materials have suitable tolerance factor, negative formation energy and good phonon spectrum, which indicates that they have structural stability. These materials are all semiconductors with band gaps varying from 0.328 eV and 3.238 eV via HSE06 hybrid functional. All the materials have direct or quasi-direct band structures, which are beneficial for carrier generation. These materials have small reflectance and large absorption coefficients for visible - infrared light, especially in the ultraviolet region where the absorption coefficient is very large. The absorption coefficient of the material is obviously improved when the anion X changes from Cl to Br to I. Making a comprehensive analysis of absorption coefficient, transmittance and bandgap values, Tl 2 PdBr 6 is regarded as a potential candidate for solar absorber in single junction solar cells, while In 2 PtCl 6 and Tl 2 PtCl 6 may be applied in transparent conductor films. [ABSTRACT FROM AUTHOR]

In order to improve the therapeutic efficacy and enhance targeted delivery of the 5-fluorouracil (5Fu) anticancer drug, a kind of potential carrier MB11N12 (M = B, Al, Ga) nanocage was designed. Density functional theory was used to evaluate the adsorption potential of raw and Al and Ca doped nanocages for the 5Fu anticancer drug. Studies on adsorption energy, dipole moment and quantum molecular descriptors show that doping can improve the drug loading capacity of nanocages. The density of states (DOS) and natural bonding orbital (NBO) studies have shown that a charge flows from nanocages to drugs, with drugs acting as charge acceptors and nanocages acting as charge donors. The interaction between drugs and nanocages was further studied using atoms in molecule (AIM) and interaction region indicator (IRI) analyses. The results showed that the drugs were mainly adsorbed on nanocages by hydrogen bonds, and this weak interaction enabled the effective release of the drugs from nanocages. In addition, doping makes the interactions between drugs and nanocages stronger and the adsorption performance better. These results indicate that B12N12 nanocages doped with Al and Ga can be used as potential carriers for the 5Fu anticancer drug. In conclusion, the results of this study can provide new ideas for the development of B12N12 nanocages as carriers for the 5Fu anticancer drug, and suggest researchers to consider these new systems for the development of carrier materials. [ABSTRACT FROM AUTHOR]

The aim of this work is to investigate the adsorption and release mechanism of 6‐thioguanine (6TG) on transition metal (Fe,Co,Ni)‐doped C60 and C60 fullerene nanomaterials by density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) to better understand the targeted drug delivery performance of fullerene to 6TG anticancer drug. The adsorption energy, solvation energy, and related chemical properties were calculated. According to thermodynamic analysis, the interaction between 6TG drug and fullerene nanocarriers is exothermic and spontaneous. Density of state (DOS) and natural bonding orbital (NBO) analyses showed that during the adsorption process of 6TG drug on the surface of fullerene, 6TG was the charge donor and fullerene was the charge acceptor. Atoms in molecule (AIM) and independent gradient model based on Hirshfeld partition (IGMH) analyses revealed Van der Waals and hydrogen bond interactions between the 6TG drug and fullerenes. In addition, fullerenes doped with transition metals can increase the solvation effect of the 6TG drug and shorten its release time from fullerenes. These results indicate that transition metal (Fe,Co,Ni)‐doped C60 fullerene can be the promising anticancer drug delivery system for 6TG. [ABSTRACT FROM AUTHOR]

Censored quantile regression has elicited extensive research interest in recent years. One class of methods is based on an informative subset of a sample, selected via the propensity score. Propensity score can either be estimated using parametric methods, which poses the risk of misspecification or obtained using nonparametric approaches, which suffer from "curse of dimensionality." In this study, we propose a new estimation method based on multiply robust propensity score for censored quantile regression. This method only requires one of the multiple candidate models for propensity score to be correctly specified, and thus, it provides a certain level of resistance to the misspecification of parametric models. Large sample properties, such as the consistency and asymptotic normality of the proposed estimator, are thoroughly investigated. Extensive simulation studies are conducted to assess the performance of the proposed estimator. The proposed method is also applied to a study on human immunodeficiency viruses. [ABSTRACT FROM AUTHOR]

Cesium lead halide perovskites are regarded as effective candidates for light-absorbing materials in solar cells, which have shown excellent performances in experiments such as promising power conversion efficiency. In this article, we analyze the electronic and optical properties of the orthorhombic CsPbBr3 and CsPbI3 with Cmcm space group based on the first-principles calculations, which are rarely studied experimentally and theoretically. In addition, we also analyze the properties of the cubic and orthorhombic CsPbBr3 and CsPbI3 with Pm3¯m and Pnma space groups for comparison, respectively. The optimized lattice constants of all phases of CsPbBr3 and CsPbI3 are in good agreement with the available experimental results. The calculated bandgap values of the cubic CsPbBr3 and CsPbI3, and the orthorhombic (Pnma) CsPbBr3 are in good agreement with the experimental data. The results show that the orthorhombic (Cmcm) CsPbBr3 and CsPbI3 are direct bandgap semiconductors with bandgap values of 2.358 eV and 2.062 eV, respectively, which are close to the bandgap values of their orthorhombic (Pnma) counterparts. In addition, the optical properties in the photon energy range of 0–4 eV indicate that the potential of the orthorhombic (Cmcm) CsPbBr3 and CsPbI3 as light-absorbing materials is close to that of the orthorhombic (Pnma) CsPbBr3 and CsPbI3, respectively. [ABSTRACT FROM AUTHOR]

First-principles calculation based on density functional theory (DFT) with the generalized gradient approximation (GGA) were carried out to investigate the energy band gap structure of Si and Ge nanofilms. Calculation results show that the band gaps of Si(111) and Ge(110) nanofilms are indirect structures and independent of film thickness, the band gaps of Si(110) and Ge(100) nanofilms could be transfered into the direct structure for nanofilm thickness of less than a certain value, and the band gaps of Si(100) and Ge(111) nanofilms are the direct structures in the present model thickness range (about 7 nm). Moreover, the changes of the band gaps on the Si and Ge nanofilms follow the quantum confinement effects. It will be a good way to obtain direct band gap emission in Si and Ge materials, and to develop Si and Ge laser on Si chip. [ABSTRACT FROM AUTHOR]

[Display omitted] • The geometric structures and vibration attribution analysis of 6MP, C60 and C59-X (X = Si, Al, Ti) were optimized by DFT B3LYP/6-311G(d,p) method. • The geometric structures of C60-6MP and C59-X-6MP(X = Si, Al, Ti) complexes were optimized by DFT B3LYP-D3(BJ)/6-311G(d,p) method. • The binding energies of C60-6MP and C59-X-6MP(X = Si, Al, Ti) complexes were calculated using DFT M06-2X-D3/6-311+G(2d,p) method. • The solvation energies of C60-6MP and C59-X-6MP(X = Si, Al, Ti) complexes were calculated using DFT M05-2X/ 6-31G (d) method. • Use Multiwfn software to do topological analysis of Atoms-in-molecules (AIM) of the complexs. C60 fullerenes are often used as drug carriers because of their unique geometric structure and electronic properties. To investigate whether C60 fullerenes can be used as a drug delivery system for 6-mercaptopurine (6MP), we calculated the binding energy and the solvation energy of C60-6MP complexe using density functional theory (DFT). In order to explore whether doping atoms with different properties can change the adsorption performance of 6MP on C60, we replaced one carbon atom of C60 with three different atoms of Si, Al and Ti. The results showed that the binding energy of C59-X-6MP(X = Si, Al, Ti) complexes are higher than C60-6MP complexe, and the solvation energy are lower, which indicating that doping can improve the drug delivery characteristics of C60 to make it easier to release the drug. In addition, in different atom doped fullerenes, the doped transition metal Ti fullerene is more suitable as 6MP carrier. This study provides a theoretical basis for the design of 6MP anticancer drugs in the future. [ABSTRACT FROM AUTHOR]

A new photonic approach for triangular waveform generation by making full use of the polarization sensitive characteristic of the single-drive Mach–Zehnder modulator (MZM) is proposed and experimentally demonstrated. In this method, the MZM is biased at minimum transmission point and its best modulation axis has an angle with the polarization direction of injection continuous wave (CW). Due to the polarization dependent modulation efficiency of a MZM, the odd-order modulation sidebands can be generated on the parallel polarization component but only the optical carrier is presented on the orthogonal direction. After a polarizer, the required Fourier components can be projected on the same polarization direction, which contribute a triangular pulse stream by photodetection. In the experimental demonstration, triangular waveforms with repetition frequencies of 8, 10, and 12 GHz are successfully generated, respectively. [ABSTRACT FROM AUTHOR]

Depletion effects are well known to lead to phase separation in microsystems consisting of large and small particles with short-range repulsive interactions that act over macromolecular length scales. The equilibrium mechanics between an enveloped colloidal particle and a biomembrane caused by entropy is investigated by using a continuum model. We show that the favorable contact energy stems from entropy, which is sufficient to drive engulfment of the colloidal particle, and deformation of the biomembrane determines the resistance to the engulfment of the colloidal particle. The engulfment process depends on the ratio of the radii of the larger particle and smaller particles and the bending rigidity. The results show insights into the effects of depletion on biomembrane budding and nanoparticle transportation by a vesicle. [ABSTRACT FROM AUTHOR]