The enhancement of the functional properties of materials at reduced dimensions is crucial for continuous advancements in nanoelectronic applications. Here, we report that the scale reduction leads ...to the emergence of an important functional property, ferroelectricity, challenging the long-standing notion that ferroelectricity is inevitably suppressed at the scale of a few nanometers. A combination of theoretical calculations, electrical measurements, and structural analyses provides evidence of room-temperature ferroelectricity in strain-free epitaxial nanometer-thick films of otherwise nonferroelectric strontium titanate (SrTiO3). We show that electrically induced alignment of naturally existing polar nanoregions is responsible for the appearance of a stable net ferroelectric polarization in these films. This finding can be useful for the development of low-dimensional material systems with enhanced functional properties relevant to emerging nanoelectronic devices.
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.
The field of dark matter detection is a highly visible and highly competitive one. In this paper, we propose recommendations for presenting dark matter direct detection results particularly suited ...for weak-scale dark matter searches, although we believe the spirit of the recommendations can apply more broadly to searches for other dark matter candidates, such as very light dark matter or axions. To translate experimental data into a final published result, direct detection collaborations must make a series of choices in their analysis, ranging from how to model astrophysical parameters to how to make statistical inferences based on observed data. While many collaborations follow a standard set of recommendations in some areas, for example the expected flux of dark matter particles (to a large degree based on a paper from Lewin and Smith in 1995), in other areas, particularly in statistical inference, they have taken different approaches, often from result to result by the same collaboration. We set out a number of recommendations on how to apply the now commonly used Profile Likelihood Ratio method to direct detection data. In addition, updated recommendations for the Standard Halo Model astrophysical parameters and relevant neutrino fluxes are provided. The authors of this note include members of the DAMIC, DarkSide, DARWIN, DEAP, LZ, NEWS-G, PandaX, PICO, SBC, SENSEI, SuperCDMS, and XENON collaborations, and these collaborations provided input to the recommendations laid out here. Wide-spread adoption of these recommendations will make it easier to compare and combine future dark matter results.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objectives
In Taiwan, older adults with cognitive impairment who undergo hip-fracture surgery are routinely cared for by family members. This study aimed to determine if nutritional status influenced ...the effects of a family-centered intervention for older adults with cognitive impairment recovering from hip-fracture surgery.
Design
Secondary data analysis of data from a randomized controlled trial was conducted to examine the influences of nutritional status 1 month after hospital discharge on the effects of a family-centered care intervention model, which was designed for older adults with hip fracture and cognitive impairment. Outcomes were compared among participants according to nutrition status (well-nourished/poorly-nourished) and treatment approach (control/intervention).
Setting
The original study was conducted at a 3000-bed medical center from July 2015 to October 2019.
Participants
Participants were older adults with cognitive impairment who had undergone hip-fracture surgery. Participants were assessed as poorly-nourished or well-nourished with the Mini-Nutritional Assessment (MNA) 1-month post-discharge and were then randomly assigned to either the intervention group or control group. Intervention: A family-centered intervention model for family caregivers of older adults with cognitive impairment recovering from hip-fracture surgery was implemented. The intervention was delivered by geriatric nurses, which included instructions for family caregivers in overseeing exercises for strengthening the hip, understanding dietary requirements, and managing behavioral problems associated with cognitive impairment.
Measurements
Outcome measures included activities of daily living (ADLs), instrumental ADLs, hip range of motion, hip muscle strength, depression, measured with the Geriatric Depressive Scale, and physical and mental health related quality of life, measured with the Short Form Survey (SF-36), Taiwanese version. Participants were assessed at 1-, 3-, 6-, and 12-months post-discharge.
Results
Most of the 134 participants were assessed as poorly nourished (n = 122); 57 were the control group and 65 received the intervention. For the well-nourished participants (n = 12), four were in the intervention group and eight were controls. There were no significant differences in any outcome variables for poorly nourished participants who received the intervention compared with controls. For the sample of well-nourished participants, those who received the intervention performed significantly better in outcomes of IADLs (b = 1.74, p <.05), hip muscle strength (b = 9.64, p <.01), and physical health related quality of life (b = 10.47, p <.01).
Conclusion
The family-centered care intervention was only effective for older adults with cognitive impairment recovering from hip-fracture surgery who were well-nourished at 1 month following hospital discharge, but not for those at risk of malnutrition. Interventions should focus on enhancing nutritional status following hip surgery which could allow the family-centered in-home intervention to be beneficial for more older adults with cognitive impairment recovering from hip-fracture surgery.
The brain endothelium is an important therapeutic target for the inhibition of cerebrovascular dysfunction in ischemic stroke. Previously, we documented the important regulatory roles of microRNAs in ...the cerebral vasculature, in particular the cerebral vascular endothelium. However, the functional significance and molecular mechanisms of other classes of non-coding RNAs in the regulation of cerebrovascular endothelial pathophysiology after stroke are completely unknown.
Using RNA sequencing (RNA-seq) technology, we profiled long non-coding RNA (lncRNA) expressional signatures in primary brain microvascular endothelial cells (BMECs) after oxygen–glucose deprivation (OGD), an in vitro mimic of ischemic stroke conditions. After 16h of OGD exposure, the expression levels for 362 of the 10,677 lncRNAs analyzed changed significantly, including a total of 147 lncRNAs increased and 70 lncRNAs decreased by more than 2-fold. Among them, the most highly upregulated lncRNAs include Snhg12, Malat1, and lnc-OGD 1006, whereas the most highly downregulated lncRNAs include 281008D09Rik, Peg13, and lnc-OGD 3916. Alteration of the most highly upregulated/downregulated ODG-responsive lncRNAs was further confirmed in cultured BMECs after OGD as well as isolated cerebral microvessels in mice following transient middle cerebral artery occlusion (MCAO) and 24h reperfusion by the quantitative real-time PCR approach. Moreover, promoter analysis of altered ODG-responsive endothelial lncRNA genes by bioinformatics showed substantial transcription factor binding sites on lncRNAs, implying potential transcriptional regulation of those lncRNAs. These findings are the first to identify OGD-responsive brain endothelial lncRNAs, which suggest potential pathological roles for these lncRNAs in mediating endothelial responses to ischemic stimuli. Endothelial-selective lncRNAs may function as a class of novel master regulators in cerebrovascular endothelial pathologies after ischemic stroke.
•A first study to profile ischemic-responsive brain endothelial long non-coding RNAs•Total 217 lncRNAs were classified as ischemic-responsive endothelial lncRNAs.•The most highly altered lncRNAs were confirmed in brain microvessels after stroke.•Identified key transcription factors that regulate ischemic-responsive lncRNAs
Cognitive impairment is a core feature of schizophrenia. Its relationship with duration of untreated psychosis (DUP), a potentially malleable prognostic factor, has been less studied, with ...inconsistent findings being observed in the literature. Previous research investigating such a relationship was mostly cross-sectional and none of those prospective studies had a follow-up duration beyond 2 years. Method A total of 93 Hong Kong Chinese aged 18 to 55 years presenting with first-episode schizophrenia-spectrum disorder were studied. DUP and pre-morbid adjustment were measured using a structured interview incorporating multiple sources of information. Psychopathological evaluation was administered at intake, after clinical stabilization of the first psychotic episode, and at 12, 24 and 36 months. Cognitive functions were measured at clinical stabilization, and at 12, 24 and 36 months.
DUP exerted differential effects on various cognitive domains, with memory deficits being the most related to DUP even when potential confounders including pre-morbid adjustment and sex were adjusted. Prolonged DUP was associated with more severe impairment in visual memory at clinical stabilization and verbal memory at 24 and 36 months. Further, patients with a long DUP were found to have worse outcomes on negative symptoms at 36 months. The effects of DUP on verbal memory remained significant even when negative symptoms were taken into consideration.
Our findings provided further supportive evidence that delayed treatment to first-episode psychosis is associated with poorer cognitive and clinical outcomes. In addition, DUP may specifically affect memory function and its adverse impact on verbal memory may only become evident at a later stage of the recovery process.
Background
There is increasing use of anti‐osteoporotic agents (AOA) worldwide for prevention or management of patients with osteoporosis. However, there have been reports of severe cutaneous adverse ...reactions (SCAR) induced by AOA. A recent study showed weak association between HLA and strontium ranelate (SR)‐SCAR.
Objective
To characterize patients with AOA‐SCAR and investigate the HLA association and utility of in vitro diagnostic methods.
Methods
We enrolled 16 cases with AOA‐cutaneous adverse drug reactions (cADR), including SCAR (n = 10: 8 with Stevens–Johnson syndrome SJS and 2 with drug rash with eosinophilia and systemic symptoms DRESS) and maculopapular exanthema (MPE) (n = 6) from Taiwan and Hong Kong. We analysed the clinical characteristics, outcomes, HLA alleles and in vitro testing of AOA‐SCAR, and tolerability to alternative drugs. We further performed literature review and meta‐analysis on the HLA association of AOA‐SCAR.
Results
Our data showed strontium ranelate is the most common causality of AOA‐SCAR in Asian populations. There was no cross‐hypersensitivity of SR‐SCAR with other AOA. HLA genotyping showed that SR‐SJS was most significantly associated with HLA‐A*33:03 (Pc = 5.17 × 10−3, OR: 25.97, 95% CI: 3.08–219.33). Meta‐analysis showed that HLA‐A*33:03 was associated with SR‐SJS (P = 5.01 × 10−5; sensitivity: 85.7%) in Asians. The sensitivity of lymphocyte activation test (LAT) for identifying the culprit drug of SR‐SJS was 83.3%.
Conclusions
Strontium ranelate is identified as the most notorious AOA associated with SCAR. The HLA‐A*33:03 genetic allele and LAT testing may add benefits to the diagnosis of SR‐SCAR in patients whose reaction developed while taking multiple drugs.
Linked Commentary: T. Shiohara. J Eur Acad Dermatol Venereol 2021; 35: 567‐568. https://doi.org/10.1111/jdv.17138.
Despite its importance, the death rate of ovarian cancer has remained unchanged over the past five decades, demanding an improvement in prevention and treatment of this malignancy. With no known ...carcinogens, targeted prevention is currently unavailable, and efforts in early detection of this malignancy by screening biomarkers have failed. The inhibition of angiogenesis, also known as angioprevention, is a promising strategy to limit the growth of solid tumors, including ovarian cancers. Nobiletin, a polymethoxy flavonoid compound isolated from the tiansheng plant, has been shown to inhibit the growth of multiple types of human cancers. However, there are no reports involving the effect on nobiletin on human ovarian cancer. The present report shows that nobiletin potently decreases the viability of ovarian cancer cells in vitro. However, nobiletin does not affect the viability of normal ovarian epithelial cells at <40 μM. The antitumor activity of nobiletin was also observed in athymic mouse models and in chicken chorioallantoic membrane (CAM) models. The anti-neoplastic activity of nobiletin was due to its ability to inhibit angiogenesis. We also studied the molecular mechanisms by which nobiletin suppresses angiogenesis. We observed that nobiletin inhibits secretion of the key angiogenesis mediators, Akt, HIF-1α, NF-κB and vascular epithelial growth factor (VEGF) by ovarian cancer cells. Transient transfection experiments showed that nobiletin inhibits production of HIF-1α by downregulation of Akt. Such decreased levels of HIF-1α were responsible for nobiletin-induced suppression of VEGF. Our data suggest that nobiletin may be a promising anti-angiogenic agent relevant for therapy of ovarian cancers.
Out-of-plane ferroelectricity with a high transition temperature in nanometer-scale films is required to miniaturize electronic devices. Direct visualization of stable ferroelectric polarization and ...its switching behavior in atomically thick films is critical for achieving this goal. Here, ferroelectric order at room temperature in the two-dimensional limit is demonstrated in tetragonal BiFeO
ultrathin films. Using aberration-corrected scanning transmission electron microscopy, we directly observed robust out-of-plane spontaneous polarization in one-unit-cell-thick BiFeO
films. High-resolution piezoresponse force microscopy measurements show that the polarization is stable and switchable, whereas a tunneling electroresistance effect of up to 370% is achieved in BiFeO
films. Based on first-principles calculations and Kelvin probe force microscopy measurements, we explain the mechanism of polarization stabilization by the ionic displacements in oxide electrode and the surface charges. Our results indicate that critical thickness for ferroelectricity in the BiFeO
film is virtually absent, making it a promising candidate for high-density nonvolatile memories.
The study was conducted to delineate fundamental mechanisms that initiate the deleterious effect of fuel overloading on reproductive efficacy of broiler breeder hens. Sixty hens at age 26 wk were fed ...recommended amounts of feed (160 g/d per hen) or allowed voluntary feeding (approximately 30% more than restriction). At age 35 and 50 wk, hens were sampled for further analyzes. Voluntary feeding resulted in poor egg production, high rate of mortality, and abnormal ovarian structure (mainly overt hierarchical follicle atresia at age 35 wk and ovarian involution at age 50 wk). In contrast to feed-restricted hens, voluntary feeding also induced metabolic dysregulations that comprised enhanced adiposity; hepatic triacylglycerol accumulation; and elevated concentrations of plasma glucose, NEFAs, very low density lipoprotein, triacylglycerol, phospholipids, and sphingomyelin (P < 0.05). Furthermore, hepatic and circulating ceramide and sphingomyelin accumulation, and up-regulation of proinflammatory IL-1β expression in liver and adipose tissues (P < 0.05) systemically manifested the development of lipotoxicity in feed-satiated hens. Lipotoxicity leading to impaired ovarian dysfunctions, including follicle atresia, ovarian regression, and a decline of circulating estradiol levels (P < 0.05) in feed-satiated hens, was further exemplified by ceramide accumulation and up-regulation of IL-1β, serine palmitoyltransferase, and sphingomyelinase transcript abundance, but suppressed protein kinase Akt activation (P < 0.1 to 0.05) within the hierarchical follicles. This study provides the first in vivo evidence of the actions of ceramide and IL-1β in mediating overfeeding-induced follicle atresia and progression of ovarian involution in broiler hens.
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