Role of laparoscopy in management of patients with anterior abdominal stab wounds.

BACKGROUND: In this retrospective cohort study, we assessed the utility of laparoscopic surgery for diagnostic and therapeutic purposes in patients with anterior abdominal stab wounds (AASWs). We also investigated patient characteristics that might suggest a greater suitability of laparoscopic interventions. METHODS: Over a 25-year span, we analyzed AASW patients who had operations, categorizing them based on the presence of significant intra-abdominal injuries and whether they received laparoscopic surgery or laparotomy. We compared variables such as preoperative conditions, surgical details, and postoperative outcomes. We further evaluated the criteria indicating the necessity of direct laparotomies and traits linked to overlooked injuries in laparoscopic surgeries. RESULTS: Of 142 AASWs surgical patients, laparoscopic surgery was conducted on 89 (62.7%) patients. Only 2 (2.2%) had overlooked injuries after the procedure. Among patients without significant injuries, those receiving laparoscopic surgery had less blood loss than those receiving laparotomy (30.0 vs. 150.0 ml, p = 0.004). Patients who underwent laparoscopic surgery also had shorter hospital stays (significant injuries: 6.0 vs. 11.0 days, p < 0.001; no significant injuries: 5.0 vs. 6.5 days, p = 0.014). Surgical complications and overlooked injury rates were comparable between both surgical methods. Bowel evisceration correlated with higher laparotomy odds (odds ratio = 16.224, p < 0.001), while omental evisceration did not (p = 0.107). CONCLUSIONS: Laparoscopy is a safe and effective method for patients with AASWs, fulfilling both diagnostic and therapeutic needs. For stable AASW patients, laparoscopy could be the preferred method, reducing superfluous nontherapeutic laparotomies.

Spin-orbit splitting and piezoelectric properties of Janus Ge2XY (X ≠ Y = P, As, Sb and Bi).

The coexistence of spin-orbit coupling and piezoelectricity in a single material may have potential application in multifunctional devices, including spintronics, nanorobotics and piezotronics. Spin-orbit coupling provides a new means to manipulate electron's spin without an additional external magnetic field, while piezoelectricity refers to the interplay between mechanical stresses and electric polarization. Using first-principles calculations, the structural, electronic, optical, spin, and piezoelectric properties of the Janus Ge2XY (X ≠ Y = P, As, Sb, and Bi) monolayers were systematically investigated. All the Ge2XY are energetically and dynamically stable in the α phase. At the GW level, Ge2AsSb, Ge2AsBi, and Ge2SbBi have direct fundamental band gaps of 0.65, 0.64, and 0.91 eV. At the GW + BSE level, their optical gaps are 0.42, 0.45, and 0.63 eV, and the optical absorption coefficients can reach about 10-5 cm-1 in the infrared light region, which reveals that they have potential for application in infrared photodetectors. For Ge2PBi, Ge2AsBi, and Ge2SbBi containing the heavy Bi element, the lowermost conduction band and uppermost valence band have large spin splitting along the M-K and K-Γ lines, and the bands near the Fermi level possess Rashba spin splitting at the Γ point. Ge2PBi and Ge2SbBi have both large in-plane piezoelectric coefficients d11 (-0.75 and -3.18 pm V-1) and out-of-plane piezoelectric coefficients d31 (0.37 and 0.30 pm V-1). Our findings are helpful to understand the mechanism of the spin-orbit physics and piezoelectricity of Janus Ge2XY monolayers and guide experiments in exploring novel multifunctional materials.

Intraoperative ultrasound is valuable for detecting intracranial hematoma progression and decreasing mortality in traumatic brain injury.

BACKGROUND: Our aim was to explore the clinical benefit of intraoperative ultrasound in decompressive craniectomy (DC) for traumatic brain injury (TBI). METHODS: From January 1, 2018, through April 30, 2021, 54 patients who developed acute subdural hematoma (SDH) due to blunt injury and underwent DC with or without intraoperative ultrasound assistance were retrospectively included in our study. Logistic regression analyses were performed to compare the therapeutic efficacy in the two groups. RESULTS: In the ultrasound group (14 patients, 25.93%), intraoperative ultrasound was used for assisting hematoma removal and/or ventriculostomy during DC. In the control group (40 patients, 74.07%), ultrasound was not used during the operation and ventriculostomy was not performed. No statistically significant differences in age, sex, initial Glasgow Coma Scale (GCS) score, blood loss, postoperative intracranial pressure (ICP), duration of hyperosmolar therapy, or Glasgow Outcome Scale Extended (GOS-E) score 6 months after injury were observed. No mortality was recorded in the ultrasound group. The mortality rate in the control group during hospitalization was 25% (p < 0.05). CONCLUSIONS: Intraoperative ultrasound is helpful for intracranial hematoma removal and ventriculostomy with cerebrospinal fluid drainage and decreases mortality in experienced hands. The reason for higher mortality rate in the control group might result from poor hematoma clearance rate and poor postoperative intracranial pressure control. It is a useful tool for diagnosing and assisting with treatment in cases of TBI.

Nitric Oxide Mobilizes Intracellular Zn2+ via the GC/cGMP/PKG Signaling Pathway and Stimulates Adipocyte Differentiation.

Plasma and tissue zinc ion levels are associated with the development of obesity. Previous studies have suggested that zinc ions may regulate adipocyte metabolism and that nitric oxide (NO) plays a pivotal role in the regulation of adipocyte physiology. Our previous study showed that chronic NO deficiency causes a significant decrease in adipose tissue mass in rats. Studies also suggested that zinc ions play an important modulatory role in regulating NO function. This study aims to explore the role of zinc ions in NO-regulated adipocyte differentiation. We hypothesized that NO could increase intracellular Zn2+ level and then stimulate adipocyte differentiation. ZnCl2 and the NO donor, NONOate, were used to explore the effects of Zn2+ and NO on adipocyte differentiation. Regulatory mechanisms of NO on intracellular Zn2+ mobilization were determined by detection. Then, Zn2+-selective chelator TPEN was used to clarify the role of intracellular Zn2+ on NO-regulated adipocyte differentiation. Furthermore, the relationship between adipocyte size, Zn2+ level, and NOS expression in human subcutaneous fat tissue was elucidated. Results showed that both ZnCl2 and NO stimulated adipocyte differentiation in a dose-dependent manner. NO stimulated intracellular Zn2+ mobilization in adipocytes through the guanylate cyclase (GC)/cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG) pathway, and NO-stimulated adipocyte differentiation was Zn2+-dependent. In human subcutaneous adipose tissue, adipocyte size was negatively correlated with expression of eNOS. In conclusion, NO treatment stimulates intracellular Zn2+ mobilization through the GC/cGMP/PKG pathway, subsequently stimulating adipocyte differentiation.

Determination of the site preference on the structure, magnetism and mechanical anisotropy properties of Mo-containing alloy carbide M6C (M=Fe, Mo).

First-principles calculations are used to study the structure, magnetism and mechanical anisotropy properties of M6C (M = Fe, Mo) carbides. The stability of alloy carbide M6C can be improved when Mo atoms occupy the 48f Wyckoff position. Fe3Mo3C with Mo atoms occupying 48f position and Fe atoms occupying 16d and 32e positions has the best structural stability. The magnetic moment is triggered when the Fe content is approximately 0.5, suggesting that there exists a critical value between the paramagnetic nature and ferromagnetism. Carbides with Fe content above 0.5 have stronger magnetism. Higher Fe content corresponds to the stronger chemical bonding of carbides, resulting in improved elastic properties when Mo atoms are held in 48f position. The special carbides Fe4Mo2C and Fe3Mo3C (Fe at 48f site, Mo at 16d and 32e sites) correspond to the excellent mechanical properties. These results are helpful in providing a theoretical foundation of the possible direction for the advances of the excellent physical properties in Mo-containing steel.

Molecular target therapeutics of EGF-TKI and downstream signaling pathways in non-small cell lung cancers.

Lung carcinoma (LC) is the third most common cancer diagnosis and accounted for the most cancer-related mortality worldwide in 2018. Based on the type of cells from which it originates, LC is commonly classified into non-small cell lung cancers (NSCLC) and small cell lung cancers (SCLC). NSCLC account for the majority of LC and can be further categories into adenocarcinoma, large cell carcinoma, and squamous cell carcinoma. Accurate classification of LC is critical for its adequate treatment and therapeutic outcome. Since NSCLC express more epidermal growth factor receptor (EGFR) with activation mutations, targeted therapy EGFR-tyrosine kinase inhibitors (TKIs) have been considered as primary option of NSCLC patients with activation EGFR mutation. In this review, we present the genetic alterations, reported mutations in EGFR, and TKIs treatment in NSCLC patients with an emphasis on the downstream signaling pathways in NSCLC progression. Among the signaling pathways identified, mitogen activation protein kinase (MAPK), known also as extracellular signal-regulated protein kinase (Erk) pathway, is the most investigated among the related pathways. EGFR activation leads to the autophosphorylation of its kinase domain and subsequent activation of Ras, phosphorylation of Raf and MEK1/2, and the activation of ERK1/2. Phosphatidylinositol 3-kinase (PI3K)/Akt is another signal pathway that regulates cell cycle and has been linked to NSCLC progression. Currently, three generations of EGFR TKIs have been developed as a first-line treatment of NSCLC patients with EGFR activation and mutation in which these treatment options will be further discussed in this review. The Supplementary Appendix for this article is available at http://links.lww.com/JCMA/A138.

Janus Ga2SeTe/In2SSe heterostructures: tunable electronic, optical, and photocatalytic properties.

Vertically stacking two-dimensional materials into van der Waals (vdW) heterostructures (HS) is deemed to be an effective strategy to tailor their physical properties and enrich their applications in modern nanoelectronics. Here, we study the geometry, electronic, and optical properties of Janus Ga2SeTe/In2SSe heterostructures by using first-principles calculations. We consider four models of Ga2SeTe/In2SSe heterostructures with an alternative chalcogen atom layer sequence and five potential stacking configurations, and find that the most energy favorable stacking pattern is AB stacking for each model. The heterostructures form type II alignment with a direct band gap. Moreover, the band gap values are highly dependent on the magnitude of the electric dipole, which is related to the sublayer intrinsic dipole direction and interface charge transfer. Additionally, the optical absorption of the heterostructures is intensified in the visible and ultraviolet regime. Furthermore, we predict two heterostructures with the band edge straddling the water redox potential level. These findings can help in understanding the tailored properties of the heterostructures based on Janus two-dimensional materials, and guide experiments in designing novel optoelectronic devices.

Degradation performance and mechanism toward methyl orange via nanoporous copper powders fabricated by dealloying of ZrCuNiAl metallic glassy precursors.

The catalyst of nanoporous Cu (NP-Cu) powders, with the chemical composition of Cu79.63Ni6.85O13.53(at%), was successfully fabricated by dealloying of Zr-Cu-Ni-Al metallic glassy precursors. The as-prepared NP-Cu powders, co-existing with Cu2O phase on Cu ligament surface, had a three-dimensional network porous structure. The NP-Cu powders/H2O2system showed superior catalytic degradation efficiency toward azo dyes in both acidic (pH 2) and neutral (pH 7) environments. Moreover, the cyclic tests indicated that this powder catalyst also exhibited good durability. A novel degradation mechanism of NP-Cu powders/H2O2was proposed: the high degradation performance in acidic environment was mainly derived from heterogeneous reaction involved with a specific pathway related to Cu3+to produce HO·, while in neutral environment it was primarily resulted from homogeneous reaction with the generation of HO· from the classical Cu-based Fenton-like process. This work indicates that the NP-Cu powders have great potential applications as catalysts for wastewater treatments.

PBK Expression Is Associated With Prognosis of Patients With Oral Squamous Cell Carcinoma Treated With Radiotherapy: A Retrospective Study.

BACKGROUND/AIM: To investigate the impact of PDZ-binding kinase (PBK) on the clinical outcome of patients with oral squamous cell carcinoma (OSCC) who received radiotherapy. PATIENTS AND METHODS: PBK immunoreactivity of cancer specimens obtained from 179 patients with primary OSCC was analyzed by immunohistochemistry. RESULTS: High PBK expression in tumor cells tended to be associated with advanced N-stage. The 5-year survival rate was greater for patients with high total PBK expression than in those with low PBK expression. After adjustment, high PBK remained associated with a favorable outcome. In subgroups according to tumor stage, the prognostic role was significant in patients with stage III/IV rather than those with stage I/II disease. CONCLUSION: We suggest that PBK expression should be used as an independent prognostic marker for patients with OSCC treated with radiotherapy, especially for those with advanced-stage disease.

Nanodiamond-based microRNA delivery system promotes pluripotent stem cells toward myocardiogenic reprogramming.

BACKGROUND: Gene therapy is the advanced therapeutics for supplying or replacing the genetic material in patients with inherited disorders. Recent clinical studies have made some progress in a wide range of applications, including monogenic disorders, neurodegenerative diseases, malignant tumors, and congenital diseases. Heart diseases, especially myocardial ischemia, remain one of the leading causes of mortality worldwide and usually result in irreparable cardiomyocyte damage and severe heart failure. METHODS: Most advances in induced pluripotent stem cell (iPSC) technologies for promoting regenerative medicine and stem cell research. However, the driver molecules of myocardial-lineage differentiation and the functional reconstruction capacity of iPSC-derived cardiomyocytes are still an open question. Nanomedicine-based gene delivery provided a crucial platform to carry on the biogenomic materials for equipping functionalities and engineering the living organ environment. Nanodiamond (ND), a carbon-based nanomaterial, has been discovered and shown the high biocompatible and less toxicity for transporting protein, drug, and genomic plasmids. RESULTS: Here, we applied ND as a gene delivery vehicle to carry microRNA (miR-181a), and then transfected into iPS to promote cardiomyocyte-lineage differentiation. Notably, miR-181a plays a key role in iPS-derived cardiomyocyte differentiation which directly targets Hox-A11, leading to elevated MyoD expression and enhanced cardiomyocyte differentiation. CONCLUSION: Our study demonstrated that miR-181a promotes iPSC differentiation into functional cardiomyocytes. Delivery of NANO-DIAMOND-miR-181a may host clinical potential to enhance the differentiation and recovery of the cardiogenic function in injured cardiomyocytes.

Generation of osimertinib-resistant cells from epidermal growth factor receptor L858R/T790M mutant non-small cell lung carcinoma cell line.

BACKGROUND: Lung cancer contributes to high cancer mortality worldwide with 80% of total cases diagnosed as non-small cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) tyrosine kinase (TK) domain serves as a druggable target in NSCLC patients with exon 19 deletion and L858R mutation. However, patients eventually succumbed to resistance to first- and second-generation EGFR-TK inhibitors through activation of T790M mutation. Third-generation EGFR-TKI, Osimertinib exhibits high efficacy in patients with exon 19 deletion/L858R/T790M mutation but they experienced acquired resistance thereafter. Available treatment options in NSCLC patients remains a challenge due to unknown molecular heterogeneity responsible for acquired resistance to EGFR-TKI. In this study, we aim to generate Osimertinib-resistant (OR) cells from H1975 carrying L858R/T790M double mutation which can be used as a model to elucidate mechanism of resistance. METHODS: OR cells were established via stepwise-dose escalation and limiting single-cell dilution method. We then evaluated Osimertinib resistance potential via cell viability assay. Proteins expression related to EGFR-signalling, epithelial to mesenchymal transition (EMT), and autophagy were analyzed via western blot. RESULTS: OR cell lines exhibited increased drug resistance potential compared to H1975. Distinguishable mesenchymal-like features were observed in OR cells. Protein expression analysis revealed EGFR-independent signaling involved in the derived OR cells as well as EMT and autophagy activity. CONCLUSION: We generated OR cell lines in-vitro as evidenced by increased drug resistance potential, increased mesenchymal features, and enhanced autophagy activity. Development of Osimertinib resistance cells may serve as in-vitro model facilitating discovery of molecular aberration present during acquired mechanism of resistance.

Using multiple-steps bioinformatic analysis to predict the potential microRNA targets by cardiogenic HoxA11.

BACKGROUND: In this study, our major aim is to using multiple-steps bioinformatic analysis to predict cardiogenic genes with targeting mRNA profiling for predicting cardiogenic HoxA11 gene. METHODS: We first analyzed the microarray data with bioinformatic measurement, including combining with panel module 1 (mouse embryonic stem cells), panel module 2 (mouse induced pluripotent stem cells), and panel module 3 (gene list form literature of heart development). A literature-based comparison of the two microarrays and a software-based (Targetscan program, www.targetscan.org) comparative analysis of the two datasets. Furthermore, we select the common central pathways and potential candidate genes involved in the cardiomyocyte-lineaged differentiation and development. RESULTS: Schematic presentation of a putative miR181a target site in Hox-A11 3'UTR. The bioinformatic result showed that potential interacted cardiogenic targets of Tbx5, Tbx20, Mal2c, Nkx2.5, cTNT, Cx43, MHC, and MCK in different treatment groups of pluripotent stem cells by using a literature-based comparison of the two microarrays and a software-based gene-lineage system. CONCLUSION: Our findings support that mir181a is an up-stream regulating microRNA to target the 3'UTR of HoxA11 mRNA during the process of cardiomyocyte differentiation.

Enhanced electro-catalytic performance of Pd-based hierarchical nanoporous structures fabricated by micropatterning and dealloying of Pd-Ni-P metallic glass.

Pd-based catalysts are of significance for their application in direct alcohol fuel cells, due to the superior electro-catalytic performance and CO poisoning resistance. In this work, using Pd32Ni48P20 metallic glassy ribbon as precursor, micro/nano hierarchical nanoporous structure was constructed by the hybrid approach of thermal plastic micropatterning and subsequently electrochemical dealloying at 0.88 V for 120 min in 0.5 M H2SO4 and 0.5 M H3PO4. This hierarchical structure was composed of the periodical micro-rods and nanoporous structure, where the chemical constituent was 80.33 at% Pd, 4.87 at% Ni, 4.96 at% P, and 9.84 at% O. The nanoporous structures showed an enhanced methanol electro-oxidation performance in alkaline medium, owing to their enlarged specific surface area. Compared to single nanoporous structure, the hierarchical nanoporous structure exhibited much better electro-catalysis, mainly attributed to the large surface area and high mass transfer efficiency, indicating a promising perspective for the application in alkaline direct alcohol fuel cells.

CircularRNA as novel biomarkers in liver diseases.

The liver is an essential organ that is primarily responsible for digestion and eliminating toxic substances from the body. After the industrial revolution, Western diet and lifestyle changes have increased the incidence of several liver diseases, including non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), liver cirrhosis, and hepatocellular carcinoma (HCC). NAFLD and NASH are mostly asymptomatic at early stages, and the disease progression from NAFLD to life-threatening HCC remains not fully understood. Circular RNA (circRNA) is consist of a circular structure, and the circRNA-microRNA(miRNA)-mRNA axes have been shown to be involved in several cellular events, including apoptosis, vascularization, metastasis, etc. The highly stable structure of circRNAs has enabled themselves to be used as putative biomarkers of several diseases. Here, we conducted a literature review and discussed the identified roles of circRNAs in NAFLD, NASH, liver cirrhosis, and HCC. For example, deficiency of circRNA_0046366 and circRNA_0046367 has been shown as the characteristics of NAFLD, and restoration of these circRNAs ameliorates the oxidative stress, lipotoxicity, and disease severity in NAFLD. Silencing of circ_0071410 was shown to alleviate hepatic stellate activation, the key step of liver cirrhosis. CDR1 and circ_0067934 can facilitate the invasion and metastasis of HCC, while circMTO1 negatively regulates the progression of HCC. Although several research works have been conducted, the whole picture of circRNA-related underlying mechanisms is unclear. Future works using high-throughput bioinformatic approaches will be needed to delineate the role of circRNAs in liver diseases and to further develop novel diagnostics and therapeutics.

The open abdomen in trauma and non-trauma patients: WSES guidelines.

Damage control resuscitation may lead to postoperative intra-abdominal hypertension or abdominal compartment syndrome. These conditions may result in a vicious, self-perpetuating cycle leading to severe physiologic derangements and multiorgan failure unless interrupted by abdominal (surgical or other) decompression. Further, in some clinical situations, the abdomen cannot be closed due to the visceral edema, the inability to control the compelling source of infection or the necessity to re-explore (as a "planned second-look" laparotomy) or complete previously initiated damage control procedures or in cases of abdominal wall disruption. The open abdomen in trauma and non-trauma patients has been proposed to be effective in preventing or treating deranged physiology in patients with severe injuries or critical illness when no other perceived options exist. Its use, however, remains controversial as it is resource consuming and represents a non-anatomic situation with the potential for severe adverse effects. Its use, therefore, should only be considered in patients who would most benefit from it. Abdominal fascia-to-fascia closure should be done as soon as the patient can physiologically tolerate it. All precautions to minimize complications should be implemented.

Value of diagnostic and therapeutic laparoscopy for patients with blunt abdominal trauma: A 10-year medical center experience.

Laparoscopy has been used for the diagnosis and treatment for hemodynamically stable patients with penetrating abdominal trauma. This study evaluated whether diagnostic and therapeutic laparoscopy can be used as effectively in select patients with blunt abdominal trauma. All hemodynamically stable patients undergoing operations for blunt abdominal trauma over a 10-year period (2006-2015) at a tertiary medical center were included. Patients undergoing laparotomy were categorized as group A. Patients who underwent laparoscopy were categorized as group B. The clinical outcomes of the 2 groups were compared. There were 139 patients in group A and 126 patients in group B. Group A patients were more severely injured (mean injury severity score of 23.3 vs. 18.9, P < .001) and had a higher frequency of traumatic brain injuries (25.2% vs. 14.3%, P = .039). The sensitivity and specificity of diagnostic laparoscopy for patients in group B was 99.1% and 100.0%, respectively. No non-therapeutic laparotomies were performed in group B, and the success rate of therapeutic laparoscopy was 92.0% (103/112) for patients with significant intra-abdominal injuries. Patients in the 2 groups had similar perioperative and postoperative outcomes in terms of operation times, blood loss, blood transfusion requirements, mortality, and complications (all, P > .05). Laparoscopy is a feasible and safe tool for the diagnosis and treatment of hemodynamically stable patients with blunt abdominal trauma who require surgery.

Traumatic left main bronchial rupture: delayed but successful outcome of robotic-assisted reconstruction.

Tracheobronchial injuries are rare but life-threatening conditions in patients with blunt thoracic trauma. The diagnosis and management of such injury may often be delayed due to other concomitant severe injuries. No reported case of a robotic-assisted bronchial reconstruction has ever been performed for a traumatic bronchial injury. A 23-year-old male suffered from traumatic left main bronchial (LMB) rupture with an initial presentation of pneumothorax and pneumomediastinum that eventually progressed to left main bronchus fibrosis and total obstruction, which led to left lung atelectasis and consolidation. Minimally invasive robotic-assisted sleeve surgery, 33 days after the initial trauma, successfully reconstructed the left main bronchus with satisfactory morphological and functional results. Recognition of a bronchial injury and precise localization of the lesion is mandated to ensure a prompt and adequate salvage surgical procedure in order to help patients recover from this critical condition.

Celastrol-induced apoptosis in human nasopharyngeal carcinoma is associated with the activation of the death receptor and the mitochondrial pathway.

Nasopharyngeal carcinoma (NPC) is a cancer that arises from the epithelium of the nasopharynx. Celastrol is a triterpene from traditional Chinese medicine, which demonstrates anti-proliferative activity in several cancer cell lines. However, the effect of celastrol on human NPC and the underlying mechanisms are not yet elucidated. The present study investigated whether celastrol induced apoptosis in human NPC cells, and the underlying molecular mechanisms were explored. Celastrol decreased the viability of HONE-1 and NPC-039 cells in a dose-dependent manner, and induced G1 and G2/M phase cell cycle arrest. The level of cleaved caspases-3, -8, and -9 and poly (ADP-ribose) polymerase 1 increased in cells treated with celastrol. There was an increase in active Bcl-2-like 11 isoform S, Bcl-2-associated X, Bcl-2 antagonist/killer and truncated BH3-interacting death antagonist, and the levels of the anti-apoptotic Bcl-2 and Bcl-2-like 1 decreased. Celastrol induced an increase in Fas, Fas-associated via death domain, TNF receptor superfamily members (TNRSF) 1A and 10B, and TNFRSF1A associated via death domain, and induced a dose-dependent reduction in mitochondrial membrane potential. Celastrol inhibited activation of mitogen-activated protein kinase (MAPK) 1/3 and 14, and induced MAPK 8/9 activation. The results indicated that celastrol induced apoptosis through the death receptor and the mitochondrial pathway in human NPC cells, and is a promising candidate in the development of drugs against NPC.

Magnetism in the p-type Monolayer II-VI semiconductors SrS and SrSe.

Using density functional theory calculations, we study the electronic and magnetic properties of the p-type monolayer II-VI semiconductors SrX (X = S,Se). The pristine SrS and SrSe monolayers are large band gap semiconductor with a very flat band in the top valence band. Upon injecting hole uniformly, ferromagnetism emerges in those system in a large range of hole density. By varying hole density, the systems also show complicated phases transition among nonmagnetic semiconductor, half metal, magnetic semiconductor, and nonmagnetic metal. Furthermore, after introducing p-type dopants in SrS and SrSe via substitutionary inserting P (or As) dopants at the S (or Se) sites, local magnetic moments are formed around the substitutional sites. The local magnetic moments are stable with the ferromagnetic order with appreciable Curie temperature. The ferromagnetism originates from the instability of the electronic states in SrS and SrSe with the large density of states at the valence band edge, which demonstrates a useful strategy for realizing the ferromagnetism in the two dimensional semiconductors.