Model-Free Feature Screening for Ultrahigh Dimensional Discriminant Analysis

<div><p>This work is concerned with marginal sure independence feature screening for ultrahigh dimensional discriminant analysis. The response variable is categorical in discriminant analysis. This enables us to use the conditional distribution function to construct a new index for feature screening. In this article, we propose a marginal feature screening procedure based on empirical conditional distribution function. We establish the sure screening and ranking consistency properties for the proposed procedure without assuming any moment condition on the predictors. The proposed procedure enjoys several appealing merits. First, it is model-free in that its implementation does not require specification of a regression model. Second, it is robust to heavy-tailed distributions of predictors and the presence of potential outliers. Third, it allows the categorical response having a diverging number of classes in the order of <i>O</i>(<i>n</i>^κ) with some κ ⩾ 0. We assess the finite sample property of the proposed procedure by Monte Carlo simulation studies and numerical comparison. We further illustrate the proposed methodology by empirical analyses of two real-life datasets. Supplementary materials for this article are available online.</p></div

Two-Dimensional Room-Temperature Magnetism in Janus Mn₂I₃S₃ and Cr₂I₃Se₃ Monolayers with Tunable Magnetic Properties by Strain Engineering

Exploring room-temperature intrinsic magnetism in two-dimensional (2D) materials for nanoscale spintronic devices has garnered significant interest. Achieving a high Curie temperature and substantial spin polarization in 2D ferromagnetic materials remains challenging. Drawing inspiration from the substantial enhancement of the Curie temperature observed in ferromagnetic CrIS monolayers by manipulating the covalent nature of Cr–S bonds, our study systematically delves into the electronic structure and magnetic properties of Janus M2X3Y3 (M = V, Cr, Mn, Fe, and Co; X = Cl, Br, I; Y = S, Se, and Te) monolayers through first-principles calculations. Our findings reveal that 15 kinds of these monolayers exhibit dynamic and thermodynamic stability while displaying diverse electronic and ferromagnetic characteristics. Notably, Mn2I3S3 demonstrates half-metallicity and in-plane magnetic anisotropy, while Cr2I3Se3 exhibits a half-semiconductor and perpendicular magnetic anisotropy. Consequently, Mn2I3S3 transforms from in-plane to perpendicular magnetic anisotropy through strain manipulation. Cr2I3Se3, under strain, transforms from a half-semiconductor to a bipolar magnetic semiconductor. The strong coupling caused by the M–Y bonds makes them have a Curie temperature higher than room temperature. The unique magnetic properties exhibited by the 2D Janus Mn2I3S3 and Cr2I3Se3 magnets hold promise for applications in spintronics. Our study provides a foundational understanding for future experimental explorations in this exciting research area

Feature Screening for Interval-Valued Response with Application to Study Association between Posted Salary and Required Skills

It is important to quantify the differences in returns to skills using the online job advertisements data, which have attracted great interest in both labor economics and statistics fields. In this paper, we study the relationship between the posted salary and the job requirements in online labor markets. There are two challenges to deal with. First, the posted salary is always presented in an interval-valued form, for example, 5k-10k yuan per month. Simply taking the mid-point or the lower bound as the alternative for salary may result in biased estimators. Second, the number of the potential skill words as predictors generated from the job advertisements by word segmentation is very large and many of them may not contribute to the salary. To this end, we propose a new feature screening method, Absolute Distribution Difference Sure Independence Screening (ADD-SIS), to select important skill words for the interval-valued response. The marginal utility for feature screening is based on the difference of estimated distribution functions via nonparametric maximum likelihood estimation, which sufficiently uses the interval information. It is model-free and robust to outliers. Numerical simulations show that the new method using the interval information is more efficient to select important predictors than the methods only based on the single points of the intervals. In the real data application, we study the text data of job advertisements for data scientists and data analysts in a major China’s online job posting website, and explore the important skill words for the salary. We find that the skill words like optimization, long short-term memory (LSTM), convolutional neural networks (CNN), collaborative filtering, are positively correlated with the salary while the words like Excel, Office, data collection, may negatively contribute to the salary.</p

Base-Free Oxidation of Alcohols to Esters at Room Temperature and Atmospheric Conditions using Nanoscale Co-Based Catalysts

The direct oxidation of alcohols to esters with molecular oxygen is an attractive and crucial process for the synthesis of fine chemicals. To date, the heterogeneous catalyst systems that have been identified are based on noble metals or have required the addition of base additives. Here, we show that Co nanoparticles embedded in nitrogen-doped graphite catalyze the aerobic oxidation of alcohols to esters at room temperature under base-free and atmospheric conditions. Our Co@C-N catalytic system features a broad substrate scope for aromatic and aliphatic alcohols as well as diols, giving their corresponding esters in good to excellent yields. This apparently environmentally benign process provides a new strategy with which to achieve selective oxidation of alcohols

Suspensible Cubic-Phase CdS Nanocrystal Photocatalyst: Facile Synthesis and Highly Efficient H₂‑Evolution Performance in a Sulfur-Rich System

Compared with stable-phase hexagonal CdS, the metastable cubic CdS photocatalyst usually shows a lower H₂-evolution performance under visible-light irradiation. Thus, the widely reported high-performance CdS photocatalysts are mainly focused on the hexagonal phase, while the cubic-phase CdS with a high H₂-evolution activity has seldom been concerned. In this study, a direct precipitation method in a sulfur-rich Na₂S–Na₂SO₃ system has been developed to prepare the suspensible cubic-phase CdS nanocrystal (<i>c</i>-CdS-NC) photocatalyst with a high H₂-evolution activity. In this case, the resultant <i>c</i>-CdS-NC with a small crystal size (ca. 5 nm) and high specific surface area (>75.23 m²/g) exhibits a stable and suspensible photocatalysts due to the massive and preferential adsorption of S^2–/SO₃^2– ions on the nanocrystal surface. Photocatalytic results indicated that the suspensible <i>c</i>-CdS-NC photocatalysts clearly exhibited an obviously higher H₂-evolution performance (0.36 mmol h^–1) than the traditional hexagonal CdS (0.14 mmol h^–1) by a factor of 2.6 times. Based on the present results, a S^2–/SO₃^2–-mediated mechanism was proposed for the enhanced H₂-evolution performance of the suspensible <i>c</i>-CdS-NC, namely the massive adsorbed S^2– ions on the suspensible <i>c</i>-CdS-NC surface not only promote the rapid capture of photogenerated holes but also can work as the effective active sites for H₂-evolution reaction. The present work may provide important insights for developing high-performance photocatalytic materials

Dietary Zinc Deficiency Exaggerates Ethanol-Induced Liver Injury in Mice: Involvement of Intrahepatic and Extrahepatic Factors

<div><p>Clinical studies have demonstrated that alcoholics have a lower dietary zinc intake compared to health controls. The present study was undertaken to determine the interaction between dietary zinc deficiency and ethanol consumption in the pathogenesis of alcoholic liver disease. C57BL/6N mice were subjected to 8-week feeding of 4 experimental liquid diets: (1) zinc adequate diet, (2) zinc adequate diet plus ethanol, (3) zinc deficient diet, and (4) zinc deficient diet plus ethanol. Ethanol exposure with adequate dietary zinc resulted in liver damage as indicated by elevated plasma alanine aminotransferase level and increased hepatic lipid accumulation and inflammatory cell infiltration. Dietary zinc deficiency alone increased hepatic lipid contents, but did not induce hepatic inflammation. Dietary zinc deficiency showed synergistic effects on ethanol-induced liver damage. Dietary zinc deficiency exaggerated ethanol effects on hepatic genes related to lipid metabolism and inflammatory response. Dietary zinc deficiency worsened ethanol-induced imbalance between hepatic pro-oxidant and antioxidant enzymes and hepatic expression of cell death receptors. Dietary zinc deficiency exaggerated ethanol-induced reduction of plasma leptin, although it did not affect ethanol-induced reduction of white adipose tissue mass. Dietary zinc deficiency also deteriorated ethanol-induced gut permeability increase and plasma endotoxin elevation. These results demonstrate, for the first time, that dietary zinc deficiency is a risk factor in alcoholic liver disease, and multiple intrahepatic and extrahepatic factors may mediate the detrimental effects of zinc deficiency.</p></div

Body weight, liver weight, and blood parameters of mice fed liquid diets for 8 weeks.

<p>Data are means ± SD (<i>n = </i>8–10). Means with different letters differ at <i>P</i><0.05. NA: not applicable. ZnA: zinc adequate diet. ZnA/E: zinc adequate diet plus ethanol. ZnD: zinc deficient diet. ZnD/E, zinc deficient diet plus ethanol. eWAT: epididymal white adipose tissue.</p

Alterations of epididymal white adipose tissue (eWAT) and leptin secretion in mice chronically fed ethanol with zinc adequate or zinc deficient diet for 8 weeks.

<p><b>A:</b> Histopathology of eWAT. H&E staining. Stars: crown-like structures indicating degenerating adipocytes surrounded by inflammatory cells. Scale car50 µm. <b>B:</b> Plasma leptin level and hepatic leptin receptor (LepRb) expression. Plasma leptin levels were measured by an ELISA kit. Hepatic LepRb was detected by qPCR setting the value of ZnA as one. Results are means ± SD (n8–10 for plasma leptin level; n = 6 for hepatic LepRb). Significant differences (<i>P</i><0.05, ANOVA) are identified by different letters. ZnA: zinc adequate diet. ZnA/E: zinc adequate diet plus ethanol. ZnD: zinc deficient diet. ZnD/E: zinc deficient diet plus ethanol.</p

Gut permeability and plasma endotoxin in mice chronically fed ethanol with zinc adequate or zinc deficient diet for 8 weeks.

<p><b>A:</b> Ileal permeability. The penetration of intralumen FITC-dextran (FD-4) to the incubation buffer was determined after incubation of the ileum sac for 20 minutes. <b>B:</b> Plasma endotoxin. Endotoxin levels were assayed by the limulus ameobocyte lysate (LAL) method. Results are means ± SD (n8–10). Significant differences (<i>P</i><0.05, ANOVA) are identified by different letters. ZnA: zinc adequate diet. ZnA/E: zinc adequate diet plus ethanol. ZnD: zinc deficient diet. ZnD/E: zinc deficient diet plus ethanol.</p

Hepatic expression of genes related to lipid metabolism in mice chronically fed ethanol with zinc adequate or zinc deficient diet for 8 weeks.

<p>qPCR analysis was conducted using SYBR green PCR mix. The relative gene expression was normalized to18s rRNA expression, and calculated using the 2^−ΔΔCt method setting the values of ZnA as one. Results are means ± SD (n6). Significant differences (<i>P</i><0.05, ANOVA) are identified by different letters. ZnA: zinc adequate diet. ZnA/E: zinc adequate diet plus ethanol. ZnD: zinc deficient diet. ZnD/E: zinc deficient diet plus ethanol.</p