Isostructural metal-insulator transition in VO2 Lee, D; Chung, B; Shi, Y ...
Science (American Association for the Advancement of Science),
11/2018, Letnik:
362, Številka:
6418
Journal Article
Recenzirano
Odprti dostop
Separating structure and electrons in VO2Above 341 kelvin—not far from room temperature—bulk vanadium dioxide (VO2) is a metal. But as soon as the material is cooled below 341 kelvin, VO2 turns into ...an insulator and, at the same time, changes its crystal structure from rutile to monoclinic. Lee et al. studied the peculiar behavior of a heterostructure consisting of a layer of VO2 placed underneath a layer of the same material that has a bit less oxygen. In the VO2 layer, the structural transition occurred at a higher temperature than the metal-insulator transition. In between those two temperatures, VO2 was a metal with a monoclinic structure—a combination that does not occur in the absence of the adjoining oxygen-poor layer.Science, this issue p. 1037The metal-insulator transition in correlated materials is usually coupled to a symmetry-lowering structural phase transition. This coupling not only complicates the understanding of the basic mechanism of this phenomenon but also limits the speed and endurance of prospective electronic devices. We demonstrate an isostructural, purely electronically driven metal-insulator transition in epitaxial heterostructures of an archetypal correlated material, vanadium dioxide. A combination of thin-film synthesis, structural and electrical characterizations, and theoretical modeling reveals that an interface interaction suppresses the electronic correlations without changing the crystal structure in this otherwise correlated insulator. This interaction stabilizes a nonequilibrium metallic phase and leads to an isostructural metal-insulator transition. This discovery will provide insights into phase transitions of correlated materials and may aid the design of device functionalities.
Cancer associated fibroblasts (CAFs) are key stroma cells that play dominant roles in tumor progression. However, the CAFs-derived molecular determinants that regulate colorectal cancer (CRC) ...metastasis and chemoresistance have not been fully characterized.
CAFs and NFs were obtained from fresh CRC and adjacent normal tissues. Exosomes were isolated from conditioned medium and serum of CRC patients using ultracentrifugation method and ExoQuick Exosome Precipitation Solution kit, and characterized by transmission electronic microscopy, nanosight and western blot. MicroRNA microarray was employed to identify differentially expressed miRNAs in exosomes secreted by CAFs or NFs. The internalization of exosomes, transfer of miR-92a-3p was observed by immunofluorescence. Boyden chamber migration and invasion, cell counting kit-8, flow cytometry, plate colony formation, sphere formation assays, tail vein injection and primary colon cancer liver metastasis assays were employed to explore the effect of NFs, CAFs and exosomes secreted by them on epithelial-mesenchymal transition, stemness, metastasis and chemotherapy resistance of CRC. Luciferase report assay, real-time qPCR, western blot, immunofluorescence, and immunohistochemistry staining were employed to explore the regulation of CRC metastasis and chemotherapy resistance by miR-92a-3p, FBXW7 and MOAP1.
CAFs promote the stemness, epithelial-mesenchymal transition (EMT), metastasis and chemotherapy resistance of CRC cells. Importantly, CAFs exert their roles by directly transferring exosomes to CRC cells, leading to a significant increase of miR-92a-3p level in CRC cells. Mechanically, increased expression of miR-92a-3p activates Wnt/β-catenin pathway and inhibits mitochondrial apoptosis by directly inhibiting FBXW7 and MOAP1, contributing to cell stemness, EMT, metastasis and 5-FU/L-OHP resistance in CRC. Clinically, miR-92a-3p expression is significantly increased in CRC tissues and negatively correlated with the levels of FBXW7 and MOAP1 in CRC specimens, and high expression of exosomal miR-92a-3p in serum was highly linked with metastasis and chemotherapy resistance in CRC patients.
CAFs secreted exosomes promote metastasis and chemotherapy resistance of CRC. Inhibiting exosomal miR-92a-3p provides an alternative modality for the prediction and treatment of metastasis and chemotherapy resistance in CRC.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary
Background
Asthma in the elderly (aged ≥ 65 years old) is a significant concern with high morbidity, but the pathophysiology remains unclear particularly in late‐onset asthma. Recent studies ...suggest staphylococcal enterotoxin IgE (SE‐IgE) sensitization to be a risk factor for asthma in general populations; however, the associations have not been examined in late‐onset elderly asthma.
Objective
We aimed to examine the associations of SE‐IgE sensitization with late‐onset asthma in the elderly, using a database of elderly asthma cohort study.
Methods
A total of 249 elderly patients with asthma and 98 controls were analysed. At baseline, patients were assessed for demographics, atopy, induced sputum profiles and comorbidities including chronic rhinosinusitis (CRS). Serum total IgE and SE‐IgE levels were measured. Asthma severity was assessed on the basis of asthma outcomes during a 12‐month follow‐up period.
Results
At baseline, serum SE‐IgE concentrations were significantly higher in patients with asthma than in controls median 0.16 (interquartile range 0.04–0.53) vs. 0.10 (0.01–0.19), P < 0.001. Elderly asthma patients with high SE‐IgE levels had specific characteristics of having more severe asthma, sputum eosinophilia and CRS, compared to those with lower SE‐IgE levels. In multivariate logistic regression analyses, the associations between serum SE‐IgE concentrations and severe asthma were significant, independently of covariables SE‐IgE‐high (≥ 0.35 kU/L) vs. negative (< 0.10 kU/L) group: odds ratio 7.47, 95% confidence interval 1.86–30.03, P = 0.005. Multiple correspondence analyses also showed that high serum SE‐IgE level had close relationships with severe asthma, CRS and sputum eosinophilia together.
Conclusions and Clinical Relevance
This is the first report on the significant associations of SE‐IgE sensitization with late‐onset asthma in the elderly, particularly severe eosinophilic asthma with CRS comorbidity. Our findings indicate a potential implication of SE in the high morbidity burden of elderly asthma and suggest clues to the pathogenesis of severe late‐onset eosinophilic asthma in the elderly.
Summary
Background
Mesenchymal stem cells (MSCs) have multiple immunomodulatory properties and hold therapeutic potential for inflammatory diseases. However, the therapeutic and immunologic effects ...of human umbilical cord blood‐derived MSCs (huMSCs) remain largely unexamined for asthma.
Objective
This study was to investigate the immunomodulatory properties of huMSCs in an ovalbumin (OVA)‐induced murine asthma model.
Methods
Mice were injected intraperitoneally with OVA and an aluminium hydroxide adjuvant. huMSCs were administered via the tail vein (5×105 cells/100 uL) to female BALB/c mice prior to the initial OVA challenge. The effects of huMSCs were assessed by investigating airway hyperresponsiveness, histological changes, inflammatory cell numbers, serum allergen‐specific antibodies, cytokine production in spleen, lung tissue, and bronchoalveolar lavage (BAL) fluid as well as expansion of regulatory T cells.
Results
Administration of huMSCs significantly reduced methacholine bronchial hyperresponsiveness and eosinophil counts in BAL cells. Similarly, there was a significant decrease in serum OVA‐specific IgE and IgG1 levels along with Th2 cytokine production (IL‐4, IL‐5, and IL‐13) in the lung and spleen tissues, whereas increased percentage of regulatory T cells was observed after treatment with huMSCs.
Conclusions
Our results suggest that huMSC treatment reduces OVA‐induced allergic inflammation, which could be mediated by regulatory T cells.
The large volume of adult living donor liver transplantations (ALDLTs) at our center affords a unique opportunity to examine the impact of acute‐on‐chronic liver failure (ACLF) among high–Model for ...End‐Stage Liver Disease MELD score patients. From February 1998 to March 2010, 1958 cirrhotic recipients were analyzed to study the relationship between MELD scores and ALDLT outcomes. A total of 327 high‐MELD score recipients were categorized into ACLF and non‐ACLF groups, and their outcomes were compared. The 5‐year graft and patient survival in the high‐MELD group were 75.2% and 76.4%, respectively, which were significantly worse than the low and intermediate MELD groups. The presence of ACLF associated with higher MELD scores appeared to be the dominant factor responsible for the inferior results of patients with MELD score of 30–34 points. The 5‐year graft survivals in the ACLF group was 70.5% and in the non‐ACLF group it was 81.0% (p = 0.035). Therefore, ALDLT should be performed as soon as possible in high‐MELD score patients prior to ACLF development. Moreover, ACLF patients should be separately categorized when analyzing the outcomes of ALDLT. ALDLT for ACLF patients should not be discouraged because favorable outcomes can be expected through timely ALDLT and comprehensive management.
While adult living donor liver transplantation should be performed as soon as possible before acute‐on‐chronic liver failure develops, it should not be discouraged for patients with acute‐on‐chronic liver failure since timely transplantation and comprehensive management can bring a favorable outcome.
p130Cas regulates cancer progression by driving tyrosine receptor kinase signaling. Tight regulation of p130Cas expression is necessary for survival, apoptosis, and maintenance of cell motility in ...various cell types. Several studies revealed that transcriptional and post-translational control of p130Cas are important for maintenance of its expression and activity. To explore novel regulatory mechanisms of p130Cas expression, we studied the effect of microRNAs (miRs) on p130Cas expression in human breast cancer MCF7 cells. Here, we provide experimental evidence that miR-362-3p and miR-329 perform a tumor-suppressive function and their expression is downregulated in human breast cancer. miR-362-3p and miR-329 inhibited cellular proliferation, migration, and invasion, thereby suppressing tumor growth, by downregulating p130Cas. Ectopic expression of p130Cas attenuated the inhibitory effects of the two miRs on tumor progression. Relative expression levels of miR-362-3p/329 and p130Cas between normal and breast cancer correlated inversely; miR-362-3p/329 expression was decreased, whereas that of p130Cas increased in breast cancers. Furthermore, we showed that downregulation of miR-362-3p and miR-329 was caused by differential DNA methylation of miR genes. Enhanced DNA methylation (according to methylation-specific PCR) was responsible for downregulation of miR-362-3p and miR-329 in breast cancer. Taken together, these findings point to a novel role for miR-362-3p and miR-329 as tumor suppressors; the miR-362-3p/miR-329-p130Cas axis seemingly has a crucial role in breast cancer progression. Thus, modulation of miR-362-3p/miR-329 may be a novel therapeutic strategy against breast cancer.
The interconversion of charge and spin currents via spin-Hall effect is essential for spintronics. Energy-efficient and deterministic switching of magnetization can be achieved when spin ...polarizations of these spin currents are collinear with the magnetization. However, symmetry conditions generally restrict spin polarizations to be orthogonal to both the charge and spin flows. Spin polarizations can deviate from such direction in nonmagnetic materials only when the crystalline symmetry is reduced. Here, we show control of the spin polarization direction by using a non-collinear antiferromagnet Mn
GaN, in which the triangular spin structure creates a low magnetic symmetry while maintaining a high crystalline symmetry. We demonstrate that epitaxial Mn
GaN/permalloy heterostructures can generate unconventional spin-orbit torques at room temperature corresponding to out-of-plane and Dresselhaus-like spin polarizations which are forbidden in any sample with two-fold rotational symmetry. Our results demonstrate an approach based on spin-structure design for controlling spin-orbit torque, enabling high-efficient antiferromagnetic spintronics.
We investigate the current-induced switching of the Néel order in NiO(001)/Pt heterostructures, which is manifested electrically via the spin Hall magnetoresistance. Significant reversible changes in ...the longitudinal and transverse resistances are found at room temperature for a current threshold lying in the range of 10^{7} A/cm^{2}. The order-parameter switching is ascribed to the antiferromagnetic dynamics triggered by the (current-induced) antidamping torque, which orients the Néel order towards the direction of the writing current. This is in stark contrast to the case of antiferromagnets such as Mn_{2}Au and CuMnAs, where fieldlike torques induced by the Edelstein effect drive the Néel switching, therefore resulting in an orthogonal alignment between the Néel order and the writing current. Our findings can be readily generalized to other biaxial antiferromagnets, providing broad opportunities for all-electrical writing and readout in antiferromagnetic spintronics.
Background
The aim of this study was to investigate the prevalence of epidemiologic and physician‐diagnosed pollen‐induced AR (PiAR) in the grasslands of northern China and to study the impact of the ...intensity and time of pollen exposure on PiAR prevalence.
Methods
A multistage, clustered and proportionately stratified random sampling with a field interviewer‐administered survey study was performed together with skin prick tests (SPT) and measurements of the daily pollen count.
Results
A total of 6043 subjects completed the study, with a proportion of 32.4% epidemiologic AR and 18.5% PiAR. The prevalence was higher in males than females (19.6% vs 17.4%, P = .024), but no difference between the two major residential and ethnic groups (Han and Mongolian) was observed. Subjects from urban areas showed higher prevalence of PiAR than rural areas (23.1% vs 14.0%, P < .001). Most PiAR patients were sensitized to two or more pollens (79.4%) with artemisia, chenopodium, and humulus scandens being the most common pollen types, which were similarly found as the top three sensitizing pollen allergens by SPT. There were significant regional differences in the prevalence of epidemiologic AR (from 18.6% to 52.9%) and PiAR (from 10.5% to 31.4%) among the six areas investigated. PiAR symptoms were positively associated with pollen counts, temperature, and precipitation (P < .05), but negatively with wind speed and pressure P < .05).
Conclusion
Pollen‐induced AR (PiAR) prevalence in the investigated region is extremely high due to high seasonal pollen exposure, which was influenced by local environmental and climate conditions.
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