Tunability of the bandgap of SnS by variation of the cell volume by alloying with A.E. elements.

We clarified that the bandgap of inorganic materials is strongly correlated with their effective coordination number (ECoN) via first-principles calculations and experimental confirmations. Tin mono-sulphide (Pnma) and germanium mono-sulphide (Pnma) were selected as model cases since these materials successively alter the ECoN as the cell volume changes and show an uncommon relationship between cell volume and bandgap. Contrary to the common semiconductors, the bandgaps of SnS (Pnma) and GeS (Pnma) have a positive relationship with respect to cell volume. This unique phenomenon was explained by incorporating the concept of ECoN into the theoretical studies. The theory proposed in this study is widely applicable to semiconductors with low-symmetry structures. Further, we experimentally demonstrated that the bandgap of SnS (Pnma) can be broadly tuned by changing the unit cell volume via alloying with alkali-earth (A.E.) metals, which could allow SnS to be applied to Si-based tandem photovoltaics. Alloying with A.E. elements also stabilised Cl as an n-type donor, which enabled n-type conduction in the bandgap-widened SnS film in the SnS-based semiconductors.

Synthesis of CaSnN2 via a High-Pressure Metathesis Reaction and the Properties of II-Sn-N2 (II = Ca, Mg, Zn) Semiconductors.

A novel ternary nitride semiconductor, CaSnN2, with a layered rock-salt-type structure (R3̅m) was synthesized via a high-pressure metathesis reaction. The properties and structures of II-Sn-N2 (II = Ca, Mg, Zn) semiconductors were also systematically studied, and the differences among them were revealed by comparison. These semiconductor materials showed a rock-salt- or wurtzite-type structure depending on the combined effect of the synthetic conditions and the characteristics of the group II elements. Additionally, the rock-salt-type structures of CaSnN2 and MgSnN2 (i.e., the ambient-pressure phase) were different from those predicted using first-principles calculations. Further, on the basis of first-principles calculations and consideration of the pressure effect, the recovered CaSnN2 sample showed an R3̅m structure. CaSnN2 and MgSnN2 showed a band gap of 2.3-2.4 eV, which is suitable for overcoming the green-light-gap problem. These semiconductors also showed a strong cathode luminescence peak at room temperature, and generalized gradient approximation (GGA) calculations revealed that CaSnN2 has a direct band gap. These inexpensive and nontoxic semiconductors (II-Sn-N2 semiconductors (II = Ca, Mg, Zn)), with mid band gaps are required as pigments to replace cadmium-based materials. They can also be used in emitting devices and as photovoltaic absorbers, replacing InxGa1-xN semiconductors.

Conduction-band effective mass and bandgap of ZnSnN2 earth-abundant solar absorber.

Pseudo III-V nitride ZnSnN2 is an earth-abundant semiconductor with a high optical absorption coefficient in the solar spectrum. Its bandgap can be tuned by controlling the cation sublattice disorder. Thus, it is a potential candidate for photovoltaic absorber materials. However, its important basic properties such as the intrinsic bandgap and effective mass have not yet been quantitatively determined. This paper presents a detailed optical absorption analysis of disordered ZnSnN2 degenerately doped with oxygen (ZnSnN2-x O x ) in the ultraviolet to infrared region to determine the conduction-band effective mass (m c*) and intrinsic bandgap (E g). ZnSnN2-x O x epilayers are n-type degenerate semiconductors, which exhibit clear free-electron absorption in the infrared region. By analysing the free-electron absorption using the Drude model, m c* was determined to be (0.37 ± 0.05)m 0 (m 0 denotes the free electron mass). The fundamental absorption edge in the visible to ultraviolet region shows a blue shift with increasing electron density. The analysis of the blue shift in the framework of the Burstein-Moss effect gives the E g value of 0.94 ± 0.02 eV. We believe that the findings of this study will provide important information to establish this material as a photovoltaic absorber.

Synthesis of ammonia using sodium melt.

Research into inexpensive ammonia synthesis has increased recently because ammonia can be used as a hydrogen carrier or as a next generation fuel which does not emit CO2. Furthermore, improving the efficiency of ammonia synthesis is necessary, because current synthesis methods emit significant amounts of CO2. To achieve these goals, catalysts that can effectively reduce the synthesis temperature and pressure, relative to those required in the Haber-Bosch process, are required. Although several catalysts and novel ammonia synthesis methods have been developed previously, expensive materials or low conversion efficiency have prevented the displacement of the Haber-Bosch process. Herein, we present novel ammonia synthesis route using a Na-melt as a catalyst. Using this route, ammonia can be synthesized using a simple process in which H2-N2 mixed gas passes through the Na-melt at 500-590 °C under atmospheric pressure. Nitrogen molecules dissociated by reaction with sodium then react with hydrogen, resulting in the formation of ammonia. Because of the high catalytic efficiency and low-cost of this molten-Na catalyst, it provides new opportunities for the inexpensive synthesis of ammonia and the utilization of ammonia as an energy carrier and next generation fuel.

A Multicenter, Randomized, Open-Label Trial: Efficacy of Once-Daily Versus Twice-Daily Double-Dose Rabeprazole on Refractory Gastroesophageal Reflux Disease-Related Symptoms and Quality of Life.

BACKGROUND: Approximately 20% to 40% of patients with gastroesophageal reflux disease (GERD) are refractory to standard-dose proton-pump inhibitor (PPI) treatment. OBJECTIVE: We compared the efficacy and quality-of-life effects of 20 mg once daily (QD) versus 10 mg twice daily (BID) rabeprazole (RPZ) in patients with refractory GERD-related symptoms and sleep disturbances. METHODS: This multicenter, prospective, randomized, open-label study included patients in whom PPI treatment >4 weeks was ineffective. According to the Global Overall Symptom (GOS) scale, PPI-refractory GERD was defined as ≥1 category with >3 points among 10 specific upper gastrointestinal symptoms. Seventy-eight patients were randomly assigned to 20 mg QD and 10 mg BID RPZ groups for 8 weeks. Efficacy was evaluated using self-reported questionnaires, including the GOS scale and Pittsburg Sleep Quality Index (PSQI), whereas quality of life was assessed using the Short-Form 8 Health Survey (SF-8), at 4 and 8 weeks. Patients showing improvement at 8 weeks received follow-up every 4 to 8 weeks. RESULTS: GOS scale scores were significantly improved at 8 weeks in both groups, with no significant intergroup differences. Although SF-8 scores showed an increasing trend over 8 weeks in both groups, the physical component summaries in the 10 mg BID group significantly improved. The mental component summaries clearly improved in the 10 mg BID group. Of the 74 cases (4 missing), 51 (68.9%) had PSQI scores ≥5.5. PSQI scores remained unchanged during follow-up in both groups. The recurrence rate was not significantly different (46.1% vs 47.1% in the 20 mg QD and 10 mg BID groups, respectively) during the follow-up period at median (interquartile range) 24.0 (30.5) months. CONCLUSIONS: In patients with refractory GERD, there was no significant difference in GOS scale score, PSQI, or recurrence rate between the groups. With regard to subscores of the SF-8, the 10 mg BID group might be potentially effective.

A novel caryophyllene type sesquiterpene lactone from Asparagus falcatus (Linn.); structure elucidation and anti-angiogenic activity on HUVECs.

In this study the novel caryophyllene type sesquiterpene lactone (aspfalcolide) has been isolated from the leaves of Asparagus falcatus (Linn.) and characterized by IR, 1D NMR, 2D NMR, EI-MS, HR-ESI-MS and X-ray single crystal diffraction analysis. The aspfalcolide crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 6.37360(10), b = 7.6890(2), c = 27.3281(6) Å, α = ß = Î³ = 90(°) and Z = 4. One intermolecular O-H⋯O hydrogen bond enforces these natural molecules to form infinite chains through the crystal. Aspfalcolide was screened for its anti-angiogenic activity in human umbilical vein endothelial cells (HUVECs) and the result showed the remarkable inhibitory effect of aspfalcolide on the proliferation (IC(50) 1.82 µM), migration and tube formation of HUVECs.

Stability of amino acids and their oligomerization under high-pressure conditions: implications for prebiotic chemistry.

The polymerization of amino acids leading to the formation of peptides and proteins is a significant problem for the origin of life. This problem stems from the instability of amino acids and the difficulty of their oligomerization in aqueous environments, such as seafloor hydrothermal systems. We investigated the stability of amino acids and their oligomerization reactions under high-temperature (180-400°C) and high-pressure (1.0-5.5 GPa) conditions, based on the hypothesis that the polymerization of amino acids occurred in marine sediments during diagenesis and metamorphism, at convergent margins on early Earth. Our results show that the amino acids glycine and alanine are stabilized by high pressure. Oligomers up to pentamers were formed, which has never been reported for alanine in the absence of a catalyst. The yields of peptides at a given temperature and reaction time were higher under higher-pressure conditions. Elemental, infrared, and isotopic analyses of the reaction products indicated that deamination is a key degradation process for amino acids and peptides under high-pressure conditions. A possible NH(3)-rich environment in marine sediments on early Earth may have further stabilized amino acids and peptides by inhibiting their deamination.

Effects of menadione, a reactive oxygen generator, on leukotriene secretion from RBL-2H3 cells.

Reactive oxygen species (ROS) are produced in various cells and affect many biological processes. We previously reported that 2-methyl-1,4-naphtoquinone (menadione) inhibited Ca(2+) influx from the extracellular medium and exocytosis evoked by antigen stimulation in the mast cell line, RBL-2H3. Mast cells release various inflammatory mediators such as leukotrienes (LTs) and cytokines in addition to the exocytotic secretion of histamine. In this study, we investigated the effects of menadione on LT release in RBL-2H3. Treatment of RBL cells with menadione inhibited LTC(4) secretion induced by antigen stimulation. To elucidate the mechanism of this inhibition, we examined the effects of menadione on the activation process of 5-lipoxygenase that is responsible for the synthesis of LTs from arachidonic acid. Menadione did not affect the phosophorylation of mitogen activated protein (MAP) kinases, extracellular signal-regulated kinase (ERK) and p38, which regulates phosphorylation of 5-lipoxygenase. However, menadione inhibited the translocation of 5-lipoxygenase from the cytoplasm to the nuclear membrane. Together with the result that LT secretion was severely impaired in the absence of extracellular Ca2(2+), it is suggested that ROS produced by menadione inhibited LT secretion through impaired Ca2(2+) influx and 5-lipoxygenase translocation to the nuclear membrane.

Tension pneumocephalus as a complication of lumbar drainage for cerebral aneurysm surgery--case report.

A 66-year-old man developed tension pneumocephalus after failed lumbar drainage before clipping surgery for a ruptured anterior communicating artery aneurysm. After puncture with a Tuohy needle, the spinal catheter could not be inserted into the spinal dura, so surgery proceeded without the catheter placement. The patient's neurological status deteriorated suddenly into coma within 15 hours after uneventful clipping of the aneurysm. Computed tomography revealed tension pneumocephalus with marked brain shift. Intracranial hypotension was probably caused by continuous cerebrospinal fluid leakage from the iatrogenic spinal dural tear, resulting in air entry and accumulation into the cranium from an unidentified opening of the cranial dura. The patient was immediately treated with autologous epidural blood patch administration in the lumbar spine, followed by reopening of the craniotomy incision and flap to evacuate the accumulated air. The patient made a quick and uneventful neurological recovery after the rescue procedure.

Effects of 2-methyl-1,4-naphtoquinone (menadione) on cellular signaling in RBL-2H3 cells.

Reactive oxygen species (ROS) are produced in various cells and affect many biologic processes. In this study, we examined the effects of 2-methyl-1,4-naphtoquinone (menadione; vitamin K3) on signal transduction in mast cells. Several lines of evidence suggest that H2O2 affects the antigen-induced responses in mast cells but its mechanism is not clearly understood. Unlike H2O2, menadione produces ROS only inside cells. Thus, it is possible to investigate the effects of ROS produced intracellularly. Pretreatment of mast cells (RBL-2H3) with menadione inhibited exocytotic secretion (degranulation) induced by antigen stimulation dose dependently. Menadione also inhibited the intracellular Ca2+ increase induced by antigen stimulation. Menadione did not inhibit the Ca2+ increase due to Ca2+ release from the intracellular calcium store in the absence of extracellular Ca2+, but inhibited the Ca2+ influx from the extracellular medium. These results suggest that reactive oxygen generated inside RBL cells by menadione inhibited degranulation by decreasing Ca2+ influx through the store operated Ca2+ channel on the plasma membrane.

Abnormal gastroesophageal flap valve is highly associated with endoscopic reflux esophagitis after Helicobacter pylori eradication.

BACKGROUND: Whether or not eradicating Helicobacter pylori worsens reflux esophagitis remains controversial. We investigated the relationship between gastroesophageal flap valve grading and endoscopic reflux esophagitis (in patients with peptic ulcer and gastritis) before and after H. pylori eradication in a case controlled study. Whether endoscopic assessment of the gastroesophageal flap valve allows prediction of endoscopic reflux esophagitis development or exacerbation was also assessed. MATERIALS AND METHODS: A total of 220 patients with peptic ulcer or chronic gastritis, who received H. pylori eradication therapy, were followed for at least 6 months (range, 6-34 months) for endoscopic changes. Another 88 age- and disease-matched H. pylori-positive controls, without eradication therapy, were also enrolled. Gastroesophageal flap valve grade (I-IV) was assessed using the Hill classification. RESULTS: Endoscopic reflux esophagitis incidence was significantly (p < .01) higher in abnormal gastroesophageal flap valve (grades III and IV) than in normal gastroesophageal flap valve (grades I and II) cases in both H. pylori eradication and control groups. The rate of new endoscopic reflux esophagitis after eradication was significantly (p < .01) higher in the abnormal than in the normal gastroesophageal flap valve group (54.5% vs. 9.1%). By contrast, the endoscopic reflux esophagitis exacerbation rate in patients with endoscopic reflux esophagitis before eradication was low (4.5%) and endoscopic reflux esophagitis improvement was observed in 40.9% of these patients. CONCLUSIONS: These results suggest gastroesophageal flap valve grading by endoscopy to be useful for predicting the risk of newly developing endoscopic reflux esophagitis after H. pylori eradication, in addition to predicting the presence of endoscopic reflux esophagitis.