The comorbidity mechanism of problematic internet use and depression among Chinese college students: A cross-lagged panel network analysis.

Problematic internet use (PIU) and depression usually co-occur and are common among college students. According to network theory, it may be attributed to the interplay of symptoms that connect these two mental health problems. However, most studies have failed to examine complex and subtle connections at the symptom level and have not clarified how PIU and depression symptoms are intercorrelated, which symptoms serve as the source of comorbidity (i.e., the central symptoms), and whether such a comorbidity mechanism would change with higher grades. To explore these questions, this study examined four contemporaneous networks and three cross-lagged panel networks, visualizing the symptoms as nodes and the connections between symptoms as edges. A total of 2,420 college students (Mage = 18.35, SD = 0.84; 67.98 % girls) completed four annual surveys. Overall, the results of contemporaneous networks and cross-lagged panel networks indicated that (a) PIU and depression symptoms are intercorrelated; (b) the core symptoms responsible for comorbidity mostly belonged to PIU, and (c) the comorbidity mechanism would change with time. These findings explain the dynamic relation between PIU and depression and identify possible primary symptoms that comorbidity programs can mitigate at different stages of the college years.

Systemic metastases in large cell neuroendocrine prostate cancer: a rare case report and literature review.

Neuroendocrine prostate neoplasms, encompassing small cell carcinoma, carcinoid, and large cell carcinoma, are infrequently observed in malignant prostate tumors. The occurrence of large cell neuroendocrine prostate cancer (LCNEPC) is exceedingly rare. In this study, the patient initially presented with a persistent dysuria for a duration of one year, accompanied by a serum prostate-specific antigen (PSA) level of 17.83ng/mL. Prostate magnetic resonance imaging (MRI) and chest computed tomography (CT) scan showed that a neoplastic lesion was considered, and prostate biopsy confirmed prostate adenocarcinoma with a Gleason score of 7 (4 + 3). Then, thoracoscopic lung tumor resection was performed, and the pathological examination revealed the presence of primary moderately differentiated invasive adenocarcinoma of the lung and metastatic prostate adenocarcinoma, the Gleason score was 8 (4 + 4). After 1 year of endocrine therapy with goserelin acetate and bicalutamide, he underwent a laparoscopic radical prostatectomy (LRP), the pathological report indicated the presence of adenocarcinoma mixed with NE carcinoma. Two months after the LRP, the patient experienced gross hematuria and sacral tail pain. Further examination revealed multiple metastatic lesions throughout the body. He also underwent transurethral resection of bladder tumor (TURBT) for bladder tumor and received etoposide+ cisplatin chemotherapy three weeks post-surgery. The patient eventually died of multi-organ failure due to myelosuppression after chemotherapy. This case report presents an uncommon instance of LCNEPC with widespread systemic metastases, while also providing a comprehensive review of existing literature to facilitate improved management and treatment strategies for similar patients in subsequent cases.

A Dual-Signal Sensing for the Visual and Luminescent Detection of p-Phenylenediamine Based on Cerium-Nitrogen-Co-Doped Carbon Dots.

Herein, a visual and luminescent dual-mode (colorimetric and fluorometric) method for the detection of P-phenylenediamine (PPD) in hair dye was successfully established based on cerium-nitrogen co-doped carbon dots (Ce, N-CDs) that displayed remarkable luminescence and peroxidase activity. Ce, N-CDs catalyzed H2O2 to produce superoxide anion, which then oxidized the colorless 3,3,5,5-tetramethylbenzidine (TMB) into blue oxidized TMB (oxTMB), capable of quenching the fluorescence through fluorescence resonance energy transfer (FRET) between Ce, N-CDs and oxTMB. The reducing properties of PPD could reduce oxTMB back to TMB, leading to a decrease in the absorption intensity of oxTMB and a fluorescence recovery of Ce, N-CDs. As a result, the quantitative detection of PPD could be achieved by measuring the absorption values of oxTMB and the fluorescence signal of Ce, N-CDs. The detection limits for PPD were calculated as 0.36 µM and 0.10 µM for colorimetry and fluorimetry, respectively. Furthermore, smartphone application (ColorPicker) capable of measuring the RGB value of the color was utilized in the detection system, facilitating on-site quantitative detection. This approach effectively shortens the detection time and simplifies the operation, offering a powerful and convenient tool for real-time monitoring of PPD.

Association between dietary protein intake and constipation: Data from the National Health and nutrition examination survey 2005-2010.

BACKGROUND: The association between dietary protein intake and constipation remains inconclusive. The aim of this study was to investigate whether dietary protein intake is associated with constipation. METHODS: This cross-sectional study included 13,941 adults from the 2005 to 2010 National Health and Nutrition Examination Survey. A weighted logistic regression analysis was used to control for confounding factors. In addition, weighted interaction and stratified analyses were conducted to ascertain the potential modifying factors. RESULTS: The prevalence of constipation was 7.5% when constipation was defined by stool consistency and 3.5% when constipation was defined by stool frequency. After adjusting for covariates, an increase in dietary protein intake of 10 g was not associated with constipation, as defined by stool frequency (OR = 0.94, 95% CI = 0.54, 1.62) or stool consistency (OR = 1.02, 95% CI = 0.75, 1.39). Subgroup analyses revealed that dietary protein intake was associated with an increase in constipation defined by stool consistency risk in participants who consumed a low amount of carbohydrates (OR = 1.08, 95% CI = 1.02-1.14 for every 10-g increase in protein intake), but a decrease in risk in participants in the moderate-carbohydrate group (OR = 0.94, 95% CI = 0.89-0.99 for every 10-g increase in protein intake), suggesting a significant interaction (p = 0.001). CONCLUSION & INFERENCES: Dietary protein intake is not associated with stool consistency or frequency-defined constipation. However, the association between dietary protein intake and constipation defined by stool consistency in participants with a low carbohydrate intake differed from that in participants with a moderate carbohydrate intake.

Nanoparticle-based optical interfaces for retinal neuromodulation: a review.

Degeneration of photoreceptors in the retina is a leading cause of blindness, but commonly leaves the retinal ganglion cells (RGCs) and/or bipolar cells extant. Consequently, these cells are an attractive target for the invasive electrical implants colloquially known as "bionic eyes." However, after more than two decades of concerted effort, interfaces based on conventional electrical stimulation approaches have delivered limited efficacy, primarily due to the current spread in retinal tissue, which precludes high-acuity vision. The ideal prosthetic solution would be less invasive, provide single-cell resolution and an ability to differentiate between different cell types. Nanoparticle-mediated approaches can address some of these requirements, with particular attention being directed at light-sensitive nanoparticles that can be accessed via the intrinsic optics of the eye. Here we survey the available known nanoparticle-based optical transduction mechanisms that can be exploited for neuromodulation. We review the rapid progress in the field, together with outstanding challenges that must be addressed to translate these techniques to clinical practice. In particular, successful translation will likely require efficient delivery of nanoparticles to stable and precisely defined locations in the retinal tissues. Therefore, we also emphasize the current literature relating to the pharmacokinetics of nanoparticles in the eye. While considerable challenges remain to be overcome, progress to date shows great potential for nanoparticle-based interfaces to revolutionize the field of visual prostheses.

Characterization of the complete chloroplast genome sequence of Camellia tetracocca (Theaceae).

Camellia tetracocca H.T. Chang 1981 is an important wild relative of cultivated tea plants. Its leaves are widely used by local people to make tea, showing great economic and breeding values. We here report the complete chloroplast genome of C. tetracocca using Illumina sequencing technology. The complete chloroplast genome of C. tetracocca is 157,026 bp in length, and structurally contains a pair of inverted repeat regions (IRa and IRb, 26,052 bp) separated by a large single-copy region (LSC, 86,669 bp) and a small single-copy region (SSC, 18,253 bp). It is composed of 131 predicted genes, including 86 protein-coding genes, 37 transfer RNA genes, and eight ribosomal RNA genes. The overall GC content is 37.31%. Phylogenetic analysis among four Camellia species and 11 other close species reveals a close relationship between C. tetracocca and C. gymnogyna.

Associations Between Internet-Specific Parenting, General Parenting, and Adolescents' Online Behaviors: A Cross-Lagged Panel Network Analysis.

Parents play a crucial role in adolescents' Internet use. Both general parenting (i.e., autonomy-supportive and controlling parenting) and Internet-specific parenting (i.e., restrictive mediation, active mediation, and parental encouragement) are related to adolescents' online behaviors. However, existing studies have focused either on an Internet-specific parenting or general parenting strategy and have neglected their interaction, failing to capture the intricate nature of the parenting context of youth's online behaviors. Few studies have examined parental encouragement or acknowledged the bidirectional influence of parenting on adolescents' online behaviors. To address this gap, this study employed a cross-lagged panel network model to examine the associations among restrictive and active mediation, parental encouragement, and autonomy-supportive and controlling parenting, as well as the interplay of all five parenting strategies with adolescents' online behaviors. A total of 564 Chinese students (51.1% male; mean age = 14.54, SD = 0.7) completed the survey at two time points. The results indicate that in most cases, previous online behaviors are significant and strong predictors of subsequent parenting strategies and not vice versa, corroborating the child effect. The parent and reciprocal effects were observed in the problematic smartphone-use domain, suggesting that the effects may differ for distinct behavioral domains. The effects of parental mediation extend beyond parental encouragement, implying that risk-prevention-related parenting is an effective means of guiding adolescents' online behaviors. Autonomy-relevant general parenting is closely related to active mediation and parental encouragement, while restrictive general parenting is closely related to restrictive mediation, suggesting a consistency between Internet-specific and general parenting strategies.

Unilateral high-riding vertebral artery is associated with asymmetric morphological changes of the atlantoaxial joint: a novel risk factor for atlantoaxial osteoarthritis.

PURPOSE: This study aimed to investigate the association between unilateral high-riding vertebral artery (HRVA) and morphological changes in the atlantoaxial joint (AAJ) and to determine whether unilateral HRVA is a risk factor for atlantoaxial osteoarthritis (AAOA). METHODS: We conducted a retrospective analysis of 2496 patients admitted to our medical center between January 2020 and December 2022 who underwent CT imaging of the cervical spine. Two hundred and seventy-two patients with unilateral HRVA (HRVA group) were identified and a respective 2:1 age- and sex-matched control group without HRVA was built. Morphological parameters, including C2 lateral mass settlement (C2 LMS), C1/2 coronal inclination (C1/2 CI), lateral atlanto-dental interval (LADI), and C1/2 relative rotation angle (C1/2 RRA) were measured. The degree of AAOA was recorded. Risk factors associated with AAOA were identified using univariate and multivariable logistic regression analyses. RESULTS: The study included 61.4% women, and the overall average age of the study population was 48.7 years. The morphological parameters (C2 LMS, C1/2 CI, and LADI) in AAJ were asymmetric between the HRVA and the non-HRVA sides in the HRVA group (p < 0.001). These differences in parameters (d-C2 LMS, d-C1/2 CI, and d-LADI) between the HRVA and the non-HRVA sides, and C1/2 RRA were significantly larger than those in the control group. Eighty-three of 816 patients (10.2%) with AAOA had larger values of d-C2 LMS, d-C1/2 CI, d-LADI, and C1/2 RRA compared with the patients without AAOA (p < 0.05). The multivariable logistic regression analysis indicated that unilateral HRVA [adjusted odds ratio (OR) = 2.6, 95% CI: 1.1-6.3, p = 0.029], age in the sixth decade or older (adjusted OR = 30.2, 95% CI: 16.1-56.9, p < 0.001), women (adjusted OR = 2.1, 95% CI: 1.0-5.6, P = 0.034) were independent risk factors for AAOA. CONCLUSION: Unilateral HRVA was associated with asymmetric morphological changes of nonuniform settlement of C2 lateral mass, lateral slip of atlas, and atlantoaxial rotation displacement. Besides age ≥ 60 years and females, unilateral HRVA is an independent risk factor for AAOA.

Influences of Composite Electrodeposition Parameters on the Properties of Ni-Doped Co-Mn Composite Spinel Coatings.

To enhance the comprehensive performance of solid oxide fuel cells (SOFCs) ferritic stainless steel (FSS) interconnectors, a novel approach involving composite electrodeposition and thermal conversion is proposed to prepare Ni-doped Co-Mn composite spinel protective coatings on FSS surfaces. The process involves the composite electrodeposition of a Ni-doped Co-Mn precursor coating, followed by thermal conversion to obtain the Co-Mn-Ni composite spinel coating. Crofer 22H was used as the substrate and orthogonal experiments were designed to investigate the influences of deposition solution pH, stirring rate, cathode current density, and the element content of Mn and Ni on the surface morphology and properties of the composite coatings, respectively. The characterization of the prepared coatings was conducted through macroscopic and microscopic morphology observations of the component surface, energy dispersive spectroscopy (EDS) analysis, and area specific resistance (ASR) testing, etc. Finally, the optimized composite electrodeposition parameters and the Mn-Ni content ratio in the solution were obtained. Experimental results indicated that the composite spinel coating prepared with the optimized process parameters exhibited excellent adhesion to the substrate, and the diffusion and migration of Cr element has been effectively inhibited. Compared with the substrate, the ASR of the coated components has also been decreased simultaneously, which provided an effective method for the surface modification of SOFC FSS interconnectors.

Living Synthelectronics: A New Era for Bioelectronics Powered by Synthetic Biology.

Bioelectronics, which converges biology and electronics, has attracted great attention due to their vital applications in human-machine interfaces. While traditional bioelectronic devices utilize nonliving organic and/or inorganic materials to achieve flexibility and stretchability, a biological mismatch is often encountered because human tissues are characterized not only by softness and stretchability but also by biodynamic and adaptive properties. Recently, a notable paradigm shift has emerged in bioelectronics, where living cells, and even viruses, modified via gene editing within synthetic biology, are used as core components in a new hybrid electronics paradigm. These devices are defined as "living synthelectronics," and they offer enhanced potential for interfacing with human tissues at informational and substance exchange levels. In this Perspective, the recent advances in living synthelectronics are summarized. First, opportunities brought to electronics by synthetic biology are briefly introduced. Then, strategic approaches to designing and making electronic devices using living cells/viruses as the building blocks, sensing components, or power sources are reviewed. Finally, the challenges faced by living synthelectronics are raised. It is believed that this paradigm shift will significantly contribute to the real integration of bioelectronics with human tissues.

Declined circular RNA mitofusin 2 constrains the deterioration of Wilms tumor via modulating microRNA-372-3p/transforming growth factor-ß receptor type 2 axis.

To explore the action and mechanism in which circular RNA (circRNA) mitofusin 2 (MFN2) repressed the malignant proliferation of Wilms tumor (WT) via modulating microRNA (miR)-372-3p/transforming growth factor-ß receptor type 2 (TGFBR2) axis. CircRNA MFN2 was distinctly elevated in the tissues and cells of WT patients, while miR-372-3p was silenced in the tissues and cells of WT. Test of TGFBR2, PCNA and Bax was implemented. Transfection with si-circRNA MFN2 or miR-372-3p-mimic restrained cancer cell advancement and the number of PCNA content was declined, while transfection with miR-372-3p-inhibitor was opposite, and PCNA content was augmented. MiR-372-3p-inhibitor turned around si-circRNA MFN2's therapeutic action after co-transfection with si-circRNA MFN2 + miR-372-3p-inhibitor. Ultimately, it was verified that circRNA MFN2 was negatively associated with miR-372-3p, which was negatively linked with TGFBR2, and circRNA MFN2 was positively associated with TGFBR2. To sum up, the results of this research illuminated circRNA MFN2 repressed WT's malignant proliferation via modulating miR-372-3p/TGFBR2 axis.

Ba6RE2Ti4O17 (RE = Nd, Sm, Gd, Dy-Yb): A Family of Rare-Earth-Based Layered Triangular Lattice Magnets.

The exploration of new rare-earth (RE)-based triangular-lattice materials plays a significant role in motivating the discovery of exotic magnetic states. Herein, we report a family of hexagonal perovskite compounds Ba6RE2Ti4O17 (RE = Nd, Sm, Gd, Dy-Yb) with a space group of P63/mmc, where magnetic RE3+ ions are distributed on the parallel triangular-lattice layers within the ab-plane and stacked in an 'AA'-type fashion along the c-axis. The low-temperature magnetic characterizations indicate that all synthesized Ba6RE2Ti4O17 compounds exhibit dominant antiferromagnetic (AFM) interactions and the absence of magnetic order down to 1.8 K. The isothermal magnetization and electron spin resonance results reveal the distinct magnetic anisotropy for the compounds with different RE ions. Moreover, the as-grown Ba6Nd2Ti4O17 single crystals exhibit Ising-like magnetic anisotropy with a magnetic easy-axis perpendicular to the triangle-lattice plane and no long-range magnetic order down to 80 mK, as the quantum spin liquid candidate with dominant Ising-type interactions.

Inetetamab combined with pyrotinib and chemotherapy in the treatment of breast cancer brain metastasis: A case report.

BACKGROUND: Breast cancer brain metastasis (BCBM) is an advanced breast disease that is difficult to treat and is associated with a high risk of death. Patient prognosis is usually poor, with reduced quality of life. In this context, we report the case of a patient with HER-2-positive BCBM treated with a macromolecular mAb (inetetamab) combined with a small molecule tyrosine kinase inhibitor (TKI). CASE SUMMARY: The patient was a 58-year-old woman with a 12-year history of type 2 diabetes. She was compliant with regular insulin treatment and had good blood glucose control. The patient was diagnosed with invasive carcinoma of the right breast (T3N1M0 stage IIIa, HER2-positive type) through aspiration biopsy of the ipsilateral breast due to the discovery of a breast tumor in February 2019. Immunohistochemistry showed ER (-), PR (-), HER-2 (3+), and Ki-67 (55-60%+). Preoperative neoadjuvant chemotherapy, i.e., the AC-TH regimen (epirubicin, cyclophosphamide, docetaxel-paclitaxel, and trastuzumab), was administered for 8 cycles. She underwent modified radical mastectomy of the right breast in November 2019 and received tocilizumab targeted therapy for 1 year. Brain metastasis was found 9 mo after surgery. She underwent brain metastasectomy in August 2020. Immunohistochemistry showed ER (-) and PR. (-), HER-2 (3+), and Ki-67 (10-20%+). In November 2020, the patient experienced headache symptoms. After an examination, tumor recurrence in the original surgical region of the brain was observed, and the patient was treated with inetetamab, pyrotinib, and capecitabine. Whole-brain radiotherapy was recommended. The patient and her family refused radiotherapy for personal reasons. In September 2021, a routine examination revealed that the brain tumor was considerably larger. The original systemic treatment was continued and combined with intensity-modulated radiation therapy for brain metastases, followed by regular hospitalization and routine examinations. The patient's condition is generally stable, and she has a relatively high quality of life. This case report demonstrates that in patients with BCBM and resistance to trastuzumab, inetetamab combined with pyrotinib and chemotherapy can prolong survival. CONCLUSION: Inetetamab combined with small molecule TKI drugs, chemotherapy and radiation may be an effective regimen for maintaining stable disease in patients with BCBM.

Sustainable Anionic Redox by Inhibiting Li Cross-Layer Migration in Na-Based Layered Oxide Cathodes.

The irrational utilization of an anionic electron often accompanies structural degradation with an irreversible cation migration process upon cycling in sodium-layered oxide cathodes. Moreover, the insufficient understanding of the anionic redox involved cation migration makes the design strategies of high energy density electrodes even less effective. Herein, a P3-Na0.67Li0.2Fe0.2Mn0.6O2 (P3-NLFM) cathode is proposed with the in-plane disordered Li distribution after an in-depth remolding of the Li ribbon-ordered P3-Na0.6Li0.2Mn0.8O2 (P3-NLM) layered oxide. The disordered Li sublattice in the transition metal slab of P3-NLFM leads to the dispersed |O2p orbitals, the lowered charge transfer gap, and the suppressed phase transition at high voltages. Then the enhanced Mn-O interaction and electronic stability are disclosed by the crystal orbital Hamilton population (COHP) analysis at high voltage in P3-NLFM. Furthermore, ab initio molecular dynamics (AIMD) simulation suggests the order/disorder of the transition metal layer is highly correlated with the stability of the Li sublattice. The cross-layer migration and loss of Li in P3-NLM are suppressed in P3-NLFM to enable the high reversibility upon cycling. As a result, the P3-NLFM delivers a high capacity of 163 mAh g-1 without oxygen release and an enhanced capacity retention of 81.9% (vs 42.9% in P3-NLM) after 200 cycles, which constitutes a promising approach for sustainable oxygen redox in rechargeable batteries.

Epidemiological and Whole Genome Sequencing Analysis of Restaurant Salmonella Enteritidis Outbreak Associated with an Infected Food Handler in Jiangxi Province, China, 2023.

In China, Salmonella is one of the most frequent causes of bacterial gastroenteritis, and food handlers in restaurants as an important contaminated source were rarely reported. In May 2023, an outbreak of Salmonella enterica serovar Enteritidis infection in a restaurant in Jiangxi Province, China, was investigated. Cases were interviewed. Stool samples from cases, anal swabs from restaurant employees, suspicious raw food materials, and semifinished food were collected and examined. Pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS) were performed to determine the relatedness of the pathogen isolates. Antimicrobial resistance genes and virulence genes of isolates were analyzed by WGS. The antimicrobial profile of the isolates was detected by broth microdilution, which involved 20 different antibiotics. Among the 31 patrons, 26 showed gastrointestinal symptoms. Five Salmonella Enteritidis strains were isolated from patients (2), semifinished food (2), and food handler (1). The results of PFGE and single-nucleotide polymorphism showed that these five isolates were identical clones. These findings demonstrated that this outbreak was a restaurant Salmonella Enteritidis outbreak associated with an infected food handler. The rates of resistance to nalidixic acid and colistin and intermediate resistance to ciprofloxacin were 100%, 80%, and 100%, respectively. These outbreak isolates harbored point mutation gyrA p.D87G. The cause of inconsistency between the genotype and phenotype of resistance was deeply discussed. A total of 107 virulence genes were found in each isolate, with many being associated with Salmonella pathogenicity island (SPI)-1 and SPI-2. As an overlooked contamination source, infected food handlers can easily cause large-scale outbreaks. This outbreak highlighted that the government should enhance the training and supervision of food hygiene and safety for food handlers to prevent foodborne outbreaks.

Motorized and non-motorized mixed traffic characteristics and lateral opening spacing calculation for the section of arterial highway through small towns.

A large number of motor vehicles and non-motorized vehicles mixed in the section of arterial highway crossing the town leads to many traffic problems. Therefore, it is necessary to set up a side divider between motorized and non-motorized lanes, and the appropriate spacing of lateral crossing openings to meet the needs of non-motorized vehicles crossing the highway has become a key issue that must be resolved. This paper investigates the traffic flow characteristics of mixed traffic flow on arterial highways through small town sections, and from the two dimensions of highway access efficiency and the psychological characteristics of cyclists, it calibrates the setting range of the spacing of non-motorized lateral crossing openings under different design speeds, which is used to regulate the behavior of non-motorized vehicles crossing the street, improve the safety level of the highway, reduce the lateral interference of the highway, and improve the road access efficiency. The accuracy of the research results is verified by microscopic simulation experiments, which proves that they can meet good expectations in practical engineering. The research results have theoretical significance and reference value for improving the status quo of machine-non-mixed traffic in the section of arterial highway passing through small towns, and enhancing the efficiency and safety of highway traffic. It also provides corresponding reference for the areas facing similar problems worldwide.

Dynamic DNA Methylation Regulates Season-Dependent Secondary Metabolism in the New Shoots of Tea Plants.

Plant secondary metabolites are critical quality-conferring compositions of plant-derived beverages, medicines, and industrial materials. The accumulations of secondary metabolites are highly variable among seasons; however, the underlying regulatory mechanism remains unclear, especially in epigenetic regulation. Here, we used tea plants to explore an important epigenetic mark DNA methylation (5mC)-mediated regulation of plant secondary metabolism in different seasons. Multiple omics analyses were performed on spring and summer new shoots. The results showed that flavonoids and theanine metabolism dominated in the metabolic response to seasons in the new shoots. In summer new shoots, the genes encoding DNA methyltransferases and demethylases were up-regulated, and the global CG and CHG methylation reduced and CHH methylation increased. 5mC methylation in promoter and gene body regions influenced the seasonal response of gene expression; the amplitude of 5mC methylation was highly correlated with that of gene transcriptions. These differentially methylated genes included those encoding enzymes and transcription factors which play important roles in flavonoid and theanine metabolic pathways. The regulatory role of 5mC methylation was further verified by applying a DNA methylation inhibitor. These findings highlight that dynamic DNA methylation plays an important role in seasonal-dependent secondary metabolism and provide new insights for improving tea quality.

Magnetic Field-driven Insulator-Metal Transition and Colossal Magnetoresistance of Metamagnetic Semiconductor Mercury Thiodichromite Crystals.

A facile method is developed to efficiently prepare metamagnetic mercury thiodichromite (HgCr2S4, HCS) polycrystals and single crystals, and their transport properties are studied. The resistivity of the as-prepared HCS polycrystal shows a semiconducting behavior and no magnetic field dependence in the whole temperature range. In contrast, the annealing treatment of the HCS polycrystal induces gigantic changes: an insulator-metal transition is driven by a magnetic field of 5 T, leading to colossal magnetoresistance (CMR) as high as ∼104. The HCS single crystal grown by a newly developed facile method displays similar properties with a larger CMR up to 106-107. First-principles calculation demonstrates a large spin splitting of band structures, providing the possibility of magnetic polaron existence, which is further evidenced by electron spin resonance spectra. Thus, the insulator-metal transition and CMR can be explained in a magnetic polaronic scenario. This work opens a new window for CMR-based spintronics.