Electric-Field-Induced Reversible Phase Transitions in a Spontaneously Ion-Intercalated 2D Metal Oxide.

Electric field driven reversible phase transitions in two-dimensional (2D) materials are appealing for their potential in switching applications. Here, we introduce potassium intercalated MnO2 as an exemplary case. We demonstrate the synthesis of large-area single-crystal layered MnO2 via chemical vapor deposition as thin as 5 nm. These crystals are spontaneously intercalated by potassium ions during the synthesis. We showed that the charge transport in 2D K-MnO2 is dominated by motion of hydrated potassium ions in the interlayer space. Under a few volts bias, separation of potassium and the structural water leads to formation of different phases at the opposite terminals, and at larger biases K-MnO2 crystals exhibit reversible layered-to-spinel phase transition. These phase transitions are accompanied by electrical and optical changes in the material. We used the electric field driven ionic motion in K-MnO2 based devices to demonstrate the memristive capabilities of two terminal devices.

Anti-TNF effect of combined pravastatin and cilostazol treatment in an in vivo mouse model.

Objectives: Pravastatin and cilostazol are used as lipid-lowering and antiplatelet agents, respectively. Regarding their well-known anti-inflammatory effects, the additive effect of the two drugs on anti-TNF functions has not yet been investigated. In the present investigation, the beneficial effect of combined pravastatin and cilostazol on their anti-TNF activities was assessed using an in vivo mouse model. Methods: Mice were pretreated with pravastatin and/or cilostazol (40 mg/kg of each), orally once two hour prior to an LPS (5 mg/kg, i.p.) challenge. One hour post challenge, blood and descending aorta were collected for serum TNF levels and immune cell infiltration analyses. For survival analysis, pravastatin and/or cilostazol (40 mg/kg of each) were administered 30 minutes prior to d-galactosamine administration (700 mg/kg, i.p.) and TNF (10 µg/kg, i.p.) challenge and mice survival was monitored. We also examined the effect of either drug or the combination of drugs on TNF-mediated MAPK and NF-κB signaling, using Western blot analysis. Results: Combined treatment of pravastatin and cilostazol significantly decreased serum TNF release and immune cell infiltration in the descending aorta following LPS administration, compared to each single treatment. Additionally, the combined drugs significantly decreased TNF-mediated mouse mortality and downregulated TNF-induced MAPK and NF-κB activation. Conclusions: These findings suggest that combined pravastatin and cilostazol is more effective for reducing TNF-driven inflammation through their anti-TNF activity than monotherapy.

Vestibular hemispatial neglect: patterns and possible mechanism.

Recent reports have suggested that hemispatial neglect may be a vestibular disorder at the cortical level, based on the similarities of symptoms and neural correlates between the two phenomena. If this is the case, peripheral vestibulopathy may lead to hemispatial neglect. However, the etiology of hemispatial neglect in patients with unilateral peripheral vestibulopathy remains unclear. The aims of the present study were to investigate the following: (1) if unilateral peripheral vestibulopathy might cause hemispatial neglect, and if so, (2) whether hemispatial neglect in unilateral peripheral vestibulopathy might be induced by horizontal bias for eye position and body orientation or whether it is secondary to vestibular cortical dysfunction following unilateral peripheral vestibulopathy. Twenty-five consecutive patients with acute vestibular neuritis were recruited at the Dizziness Clinic of Pusan National University Hospital. All participants underwent neglect testing and measurements of horizontal bias for eye position and head and body orientation. Hemispatial neglect occurred in 32 % of patients with unilateral peripheral vestibulopathy. The frequency of contralesional neglect was equal to that of ipsilesional neglect. All patients with hemispatial neglect showed abnormal performance in bisection tasks. The incidence and severity of the horizontal bias of eye position and head and body orientation did not differ between patients with or without hemispatial neglect. Our study demonstrates that hemispatial neglect can develop after acute unilateral peripheral vestibulopathy. Hemispatial neglect after acute unilateral peripheral vestibulopathy may be attributed to damaged vestibular subnuclei, which receive afferents from both peripheral vestibular end organs and the vestibulocerebellum and project to the ipsilateral or contralateral thalamus and vestibular cortex.

Wafer-Scale Synthesis of Highly Oriented 2D Topological Semimetal PtTe2 via Tellurization.

Platinum ditelluride (1T-PtTe2) is a two-dimensional (2D) topological semimetal with a distinctive band structure and flexibility of van der Waals integration as a promising candidate for future electronics and spintronics. Although the synthesis of large-scale, uniform, and highly crystalline films of 2D semimetals system is a prerequisite for device application, the synthetic methods meeting these criteria are still lacking. Here, we introduce an approach to synthesize highly oriented 2D topological semimetal PtTe2 using a thermally assisted conversion called tellurization, which is a cost-efficient method compared to the other epitaxial deposition methods. We demonstrate that achieving highly crystalline 1T-PtTe2 using tellurization is not dependent on epitaxy but rather relies on two critical factors: (i) the crystallinity of the predeposited platinum (Pt) film and (ii) the surface coverage ratio of the Pt film considering lateral lattice expansion during transformation. By optimizing the surface coverage ratio of the epitaxial Pt film, we successfully obtained 2 in. wafer-scale uniformity without in-plane misalignment between antiparallelly oriented domains. The electronic band structure of 2D topological PtTe2 is clearly resolved in momentum space, and we observed an interesting 6-fold gapped Dirac cone at the Fermi surface. Furthermore, ultrahigh electrical conductivity down to ∼3.8 nm, which is consistent with that of single crystal PtTe2, was observed, proving its ultralow defect density.

Layer-Controlled Growth of Single-Crystalline 2D Bi2O2Se Film Driven by Interfacial Reconstruction.

As semiconductor scaling continues to reach sub-nanometer levels, two-dimensional (2D) semiconductors are emerging as a promising candidate for the post-silicon material. Among these alternatives, Bi2O2Se has risen as an exceptionally promising 2D semiconductor thanks to its excellent electrical properties, attributed to its appropriate bandgap and small effective mass. However, unlike other 2D materials, growth of large-scale Bi2O2Se films with precise layer control is still challenging due to its large surface energy caused by relatively strong interlayer electrostatic interactions. Here, we present the successful growth of a wafer-scale (∼3 cm) Bi2O2Se film with precise thickness control down to the monolayer level on TiO2-terminated SrTiO3 using metal-organic chemical vapor deposition (MOCVD). Scanning transmission electron microscopy (STEM) analysis confirmed the formation of a [BiTiO4]1- interfacial structure, and density functional theory (DFT) calculations revealed that the formation of [BiTiO4]1- significantly reduced the interfacial energy between Bi2O2Se and SrTiO3, thereby promoting 2D growth. Additionally, spectral responsivity measurements of two-terminal devices confirmed a bandgap increase of up to 1.9 eV in monolayer Bi2O2Se, which is consistent with our DFT calculations. Finally, we demonstrated high-performance Bi2O2Se field-effect transistor (FET) arrays, exhibiting an excellent average electron mobility of 56.29 cm2/(V·s). This process is anticipated to enable wafer-scale applications of 2D Bi2O2Se and facilitate exploration of intriguing physical phenomena in confined 2D systems.

Yeast polyubiquitin unit regulates synaptonemal complex formation and recombination during meiosis.

Ubiquitin is highly conserved in most eukaryotes and involved in diverse physiological processes, including cell division, protein quality control, and protein degradation mediated by the ubiquitin-proteasome system after heat shock, glucose-starvation, and oxidative stress. However, the role of the ubiquitin gene UBI4, which contains five consecutive head-to-tail ubiquitin repeats, in meiosis has not been investigated. In this study, we show that the Saccharomyces cerevisiae polyubiquitin precursor gene, UBI4, is required to promote synaptonemal complex (SC) formation and suppress excess double-strand break formation. Moreover, the proportion of Zip1 polycomplexes, which indicate abnormal SC formation, in cells with a mutation in UBI4 (i.e., ubi4Δ cells) is higher than that of wild-type cells, implying that the UBI4 plays an important role in the early meiotic prophase I. Interestingly, although ubi4Δ cells rarely form full-length SCs in the pachytene stage of prophase I, the Zip3 foci are still seen, as in wild-type cells. Moreover, ubi4Δ cells proficiently form crossover and noncrossover products with a slight delay compared to wild-type cells, suggesting that UBI4 is dispensable in SC-coupled recombination. Our findings demonstrate that UBI4 exhibits dual functions that are associated with both positive and negative roles in SC formation and recombination during meiosis.

Diffusion-Controlled Crystallization of Calcium Phosphate in a Hydrogel toward a Homogeneous Octacalcium Phosphate/Agarose Composite.

Diffusion-controlled crystallization in a hydrogel has been investigated to synthesize organic/inorganic hybrid composites and obtain a fundamental understanding of the detailed mechanism of biomineralization. Although calcium phosphate/hydrogel composites have been intensively studied and developed for the application of bone substitutes, the synthesis of homogeneous and integrated composites remains challenging. In this work, diffusion-controlled systems were optimized by manipulating the calcium ion flux at the interface, concentration gradient, and diffusion coefficient to synthesize homogeneous octacalcium phosphate/hydrogel composites with respect to the crystal morphology and density. The ion flux and local pH play an important role in determining the morphology, density, and phase of the crystals. This study suggests a model system that can reveal the relation between local conditions and the resulting crystal phase in diffusion-limited systems and provides a synthetic method for homogeneously organized organic/inorganic composites.

Large Memory Window of van der Waals Heterostructure Devices Based on MOCVD-Grown 2D Layered Ge4 Se9.

Van der Waals (vdW) heterostructures have drawn much interest over the last decade owing to their absence of dangling bonds and their intriguing low-dimensional properties. The emergence of 2D materials has enabled the achievement of significant progress in both the discovery of physical phenomena and the realization of superior devices. In this work, the group IV metal chalcogenide 2D-layered Ge4 Se9 is introduced as a new selection of insulating vdW material. 2D-layered Ge4 Se9 is synthesized with a rectangular shape using the metalcorganic chemical vapor deposition system using a liquid germanium precursor at 240 °C. By stacking the Ge4 Se9 and MoS2 , vdW heterostructure devices are fabricated with a giant memory window of 129 V by sweeping back gate range of ±80 V. The gate-independent decay time reveals that the large hysteresis is induced by the interfacial charge transfer, which originates from the low band offset. Moreover, repeatable conductance changes are observed over the 2250 pulses with low non-linearity values of 0.26 and 0.95 for potentiation and depression curves, respectively. The energy consumption of the MoS2 /Ge4 Se9 device is about 15 fJ for operating energy and the learning accuracy of image classification reaches 88.3%, which further proves the great potential of artificial synapses.

The electrochemical properties of lithium/sulfur cell using sulfur-carbon nanotubes composite.

Sulfur electrode was prepared using sulfur-CNT composite powder. The sulfur electrode showed homogenous mixture of sulfur and the CNTs with a network structure. We investigated on the discharge behavior and cycling property of lithium/sulfur cell using sulfur electrodes with CNTs as unique conducting agents. The discharge capacity of the Li/TEGDME/S cell was about 1227 mAh/g-sulfur for the first cycle and decreased to 155 mAh/g-sulfur after 14 cycles.

Enhancement of Photoresponse on Narrow-Bandgap Mott Insulator α-RuCl3 via Intercalation.

Charge doping to Mott insulators is critical to realize high-temperature superconductivity, quantum spin liquid state, and Majorana fermion, which would contribute to quantum computation. Mott insulators also have a great potential for optoelectronic applications; however, they showed insufficient photoresponse in previous reports. To enhance the photoresponse of Mott insulators, charge doping is a promising strategy since it leads to effective modification of electronic structure near the Fermi level. Intercalation, which is the ion insertion into the van der Waals gap of layered materials, is an effective charge-doping method without defect generation. Herein, we showed significant enhancement of optoelectronic properties of a layered Mott insulator, α-RuCl3, through electron doping by organic cation intercalation. The electron-doping results in substantial electronic structure change, leading to the bandgap shrinkage from 1.2 eV to 0.7 eV. Due to localized excessive electrons in RuCl3, distinct density of states is generated in the valence band, leading to the optical absorption change rather than metallic transition even in substantial doping concentration. The stable near-infrared photodetector using electronic modulated RuCl3 showed 50 times higher photoresponsivity and 3 times faster response time compared to those of pristine RuCl3, which contributes to overcoming the disadvantage of a Mott insulator as a promising optoelectronic device and expanding the material libraries.

Growth and Interlayer Engineering of 2D Layered Semiconductors for Future Electronics.

Layered materials that do not form a covalent bond in a vertical direction can be prepared in a few atoms to one atom thickness without dangling bonds. This distinctive characteristic of limiting thickness around the sub-nanometer level allowed scientists to explore various physical phenomena in the quantum realm. In addition to the contribution to fundamental science, various applications were proposed. Representatively, they were suggested as a promising material for future electronics. This is because (i) the dangling-bond-free nature inhibits surface scattering, thus carrier mobility can be maintained at sub-nanometer range; (ii) the ultrathin nature allows the short-channel effect to be overcome. In order to establish fundamental discoveries and utilize them in practical applications, appropriate preparation methods are required. On the other hand, adjusting properties to fit the desired application properly is another critical issue. Hence, in this review, we first describe the preparation method of layered materials. Proper growth techniques for target applications and the growth of emerging materials at the beginning stage will be extensively discussed. In addition, we suggest interlayer engineering via intercalation as a method for the development of artificial crystal. Since infinite combinations of the host-intercalant combination are possible, it is expected to expand the material system from the current compound system. Finally, inevitable factors that layered materials must face to be used as electronic applications will be introduced with possible solutions. Emerging electronic devices realized by layered materials are also discussed.

Lactobacillus paracasei-derived extracellular vesicles attenuate the intestinal inflammatory response by augmenting the endoplasmic reticulum stress pathway.

Lactobacillus paracasei is a major probiotic and is well known for its anti-inflammatory properties. Thus, we investigated the effects of L. paracasei-derived extracellular vesicles (LpEVs) on LPS-induced inflammation in HT29 human colorectal cancer cells and dextran sulfate sodium (DSS)-induced colitis in C57BL/6 mice. ER stress inhibitors (salubrinal or 4-PBA) or CHOP siRNA were utilized to investigate the relationship between LpEV-induced endoplasmic reticulum (ER) stress and the inhibitory effect of LpEVs against LPS-induced inflammation. DSS (2%) was administered to male C57BL/6 mice to induce inflammatory bowel disease, and disease activity was measured by determining colon length, disease activity index, and survival ratio. In in vitro experiments, LpEVs reduced the expression of the LPS-induced pro-inflammatory cytokines IL-1α, IL-1ß, IL-2, and TNFα and increased the expression of the anti-inflammatory cytokines IL-10 and TGFß. LpEVs reduced LPS-induced inflammation in HT29 cells and decreased the activation of inflammation-associated proteins, such as COX-2, iNOS and NFκB, as well as nitric oxide. In in vivo mouse experiments, the oral administration of LpEVs also protected against DSS-induced colitis by reducing weight loss, maintaining colon length, and decreasing the disease activity index (DAI). In addition, LpEVs induced the expression of endoplasmic reticulum (ER) stress-associated proteins, while the inhibition of these proteins blocked the anti-inflammatory effects of LpEVs in LPS-treated HT29 cells, restoring the pro-inflammatory effects of LPS. This study found that LpEVs attenuate LPS-induced inflammation in the intestine through ER stress activation. Our results suggest that LpEVs have a significant effect in maintaining colorectal homeostasis in inflammation-mediated pathogenesis.

A normative study of the digit span in an educationally diverse elderly population.

OBJECTIVE: The purpose of this study was to explore the effect of demographic variables on Digit Span test (DS) performance in an educationally diverse elderly population and to provide normative information. METHODS: The DS was administered to 784 community-dwelling volunteers aged 60-90 years with an educational history of from zero to 25 years of full-time education. People with serious neurological, medical and psychiatric disorders (including dementia) were excluded. RESULTS: Age, education and gender were found to be significantly associated with performance on the DS. Based on the results obtained, DS norms were stratified by age (2 strata), education (3 strata), and gender (2 strata). CONCLUSION: Our results on DS performance suggest that both attention and working memory are influenced by age, education and gender. The present study provides reasonably comprehensive normative information on the DS for an educationally diverse elderly population.

Directional and spatial motor intentional disorders in patients with right versus left hemisphere strokes.

OBJECTIVE: Motor intentional disorders (MIDs) are characterized by dysfunction in the preparation, initiation, maintenance, and termination of goal-oriented actions. In this study, we investigated (1) whether patients with right hemisphere strokes (RHS) and left hemisphere strokes (LHS) differ in the frequency of delayed action initiation (hypokinesia) and motor impersistence; (2) whether there is a directional or hemispatial component of hypokinesia or motor impersistence; (3) whether there is an association between the presence of hemispatial neglect and tests for MID; and (4) the location of injury associated with MID. METHOD: Thirty-two patients with acute unilateral stroke (21 with RHS and 11 with LHS) and 12 age-matched healthy controls participated in the study. To determine the presence and severity of directional and spatial hypokinesia and impersistence we used a new apparatus, the Directional Movement Tester (DMT). While being tested with the DMT, the participants held a static bar located either in the right or left hemispace using either their right or left hand and upon stimulus onset pushed the bar either leftward or rightward and maintained a given force for 10 sec. RESULTS AND CONCLUSION: The frequency of hypokinesia and impersistence was higher in the RHS group than in the LHS group, but there were no hypokinetic directional or spatial asymmetries. The RHS group did demonstrate left contralesional directional impersistence, but there were no spatial asymmetries of impersistence. Signs of hemispatial neglect were not associated with these measures of MID. Participants with frontal or subcortical lesions were significantly more likely to demonstrate hypokinesia and impersistence than those with posterior lesions.

Obsessive-compulsive behavior disappearing after left capsular genu infarction.

This case report describes a 74-year-old woman with obsessive-compulsive behaviors that disappeared following a left capsular genu infarction. The patient's capsular genu infarction likely resulted in thalamocortical disconnection in the cortico-basal ganglia-thalamocortical loop, which may have caused the disappearance of her obsessive-compulsive symptoms. The fact that anterior capsulotomy has been demonstrated to be effective for treating refractory obsessive-compulsive disorder further supports this hypothesis.