Momentum‐resolved resonant inelastic X‐ray scattering on a single crystal under high pressure

A single‐crystal momentum‐resolved resonant inelastic X‐ray scattering (RIXS) experiment under high pressure using an originally designed diamond anvil cell (DAC) is reported. The diamond‐in/diamond‐out geometry was adopted with both the incident and scattered beams passing through a 1 mm‐thick diamond. This enabled us to cover wide momentum space keeping the scattering angle condition near 90°. Elastic and inelastic scattering from the diamond was drastically reduced using a pinhole placed after the DAC. Measurement of the momentum‐resolved RIXS spectra of Sr_2.5Ca_11.5Cu₂₄O₄₁ at the Cu K‐edge was thus successful. Though the inelastic intensity becomes weaker by two orders than the ambient pressure, RIXS spectra both at the center and the edge of the Brillouin zone were obtained at 3 GPa and low‐energy electronic excitations of the cuprate were found to change with pressure.     

A Redox‐Mediator‐Free Solar‐Driven Z‐Scheme Water‐Splitting System Consisting of Modified Ta3N5 as an Oxygen‐Evolution Photocatalyst

Tantalum nitride (Ta₃N₅) modified with various O₂‐evolution cocatalysts was employed as a photocatalyst for water oxidation under visible light (λ>420 nm) in an attempt to construct a redox‐mediator‐free Z‐scheme water‐splitting system. Ta₃N₅ was prepared by nitriding Ta₂O₅ powder under a flow of NH₃ at 1023–1223 K. The activity of Ta₃N₅ for water oxidation from an aqueous AgNO₃ solution as an electron acceptor without cocatalyst was dependent on the generation of a well‐crystallized Ta₃N₅ phase with a low density of anionic defects. Modification of Ta₃N₅ with nanoparticulate metal oxides as cocatalysts for O₂ evolution improved water‐oxidation activity. Of the cocatalysts examined, cobalt oxide (CoO_x) was found to be the most effective, improving the water‐oxidation efficiency of Ta₃N₅ by six to seven times. Further modification of CoO_x/Ta₃N₅ with metallic Ir as an electron sink allowed one to achieve Z‐scheme water splitting under simulated sunlight through interparticle electron transfer without the need for a shuttle redox mediator in combination with Ru‐loaded SrTiO₃ doped with Rh as a H₂‐evolution photocatalyst.     

Synthesis and redox behavior of 1,2-dihydro-1-oxabenz[a]azulen-2-ones

Three new 1,2-dihydro-1-oxabenz[a]azulen-2-one derivatives, 1a (R¹=H, R²=Me), 1b (R¹=H, R²=Ph), and 1c (R¹=COOEt, R²=Me), have been synthesized by the reaction of 2-hydroxyazulene (2a) and its 1-ethoxycarbonyl derivative 2b with ethyl acetoacetate (3a) or ethyl benzoylacetate (3b) in the presence of aluminum chloride. To our knowledge, these are the first examples of this type of compound, although the yield of the products is low in some cases. Their electronic properties were studied in detail utilizing the analyses of 1,2-dihydro-1-oxabenz[a]azulen-2-one derivative 1a by the spectroscopic and voltammetric analyses. The analyses revealed that the fused α-pyrone system lowers both the HOMO and the LUMO energies, relative to those of parent azulene (10), but has much pronounced effect on the LUMO, consequently, leading to decrease in HOMO–LUMO gap, compared with those of 10. These results should be attracted to the development of amphoteric redox materials. Reactivity toward electrophilic reagents was also examined by bromination and Vilsmeier–Haack formylation reactions of 1a. To evaluate the scope of the reaction products we have examined Sonogashira cross-coupling reaction of the bromination products with trimethylsilylacetylene and conversion of the formylation product to dibromoolefin by the reaction with phosphorous ylide prepared with CBr₄ and Ph₃P. Effective extension of the π-electron system in the ethynyl products has been revealed by the spectroscopic analysis. These reaction products would be attracted to the application as a terminal group for electronic applications.     

Factors Related to Continuation of Health Behaviours among Stroke Survivors

Purpose: This study investigated stroke survivors'' perspectives of health behaviours after stroke. We aimed to explore the actual process by which stroke survivors changed their health behaviours. Method: Semi-structured interviews were conducted with 40 people in a 1-year prospective study in the regional city of Chiba, Japan. Interviews covered views of health behaviours in order to explore why patients change their risk factors. Data were analysed using the principles of modified grounded theory. Results: Six categories related to practising health behaviours were identified: cause of stroke, antithetic thinking, awareness of the body, fear of disease progression, view of health, and psychological meaning of practise. Stroke survivors constructed a meaning of practise for each health behaviour. The recognition of previous lifestyle as cause of stroke, hope for recovery, and fear of future progression influenced health behaviours. Conclusions: The key finding of this study is that when cognitive behavioural therapy principles are enforced, an important aspect is that stroke survivors recognize the possibility that previous lifestyle was a cause of stroke and appreciate the necessity of preventing a new stroke.     

Oblique detonation waves stabilized in rectangular-cross-section bent tubes

Oblique detonation waves, which are generated by a fundamental detonation phenomenon occurring in bent tubes, may be applied to fuel combustion in high-efficiency engines such as a pulse detonation engine (PDE) and a rotating detonation engine (RDE). The present study has experimentally demonstrated that steady-state oblique detonation waves propagated stably through rectangular-cross-section bent tubes by visualizing these waves using a high-speed camera and the shadowgraph method. The oblique detonation waves were stabilized under the conditions of high initial pressure and a large curvature radius of the inside wall of the rectangular-cross-section bent tube. The geometrical shapes of the stabilized oblique detonation waves were calculated, and the results of the calculation were in good agreement with those of our experiment. Moreover, it was experimentally shown that the critical condition under which steady-state oblique detonation waves can stably propagate through the rectangular-cross-section bent tubes was the curvature radius of the inside wall of the rectangular-cross-section bent tube equivalent to 14–40 times the cell width.     

A Dirichlet space associated with consistent networks on the ring of <Emphasis Type="Italic">p</Emphasis>-adic Integers

In this article, we will give a method of reconstruction of a random walk in the ring of p-adic integers. Paying attention to a structural importance in the self similarity, we will perform the construction by means of modified method for constructing canonical stochastic processes on fractals in the Euclidean space. As a result, we will obtain an important subfamily of Albeverio and Karwowski’s stochastic processes with a self-similar randomness.     

A natural protecting group strategy to carry an amino acid starter unit in the biosynthesis of macrolactam polyketide antibiotics

Macrolactam antibiotics are an important class of macrocyclic polyketides that contain a unique nitrogen-containing starter unit. In the present study, a set of starter biosynthetic enzymes in the macrolactam antibiotic vicenistatin was characterized. We found that the protection-deprotection strategy of the aminoacyl-ACP intermediate was critical in this system. On the basis of bioinformatics, the described pathway is also proposed as a common method for carrying amino acids in the biosynthesis of other macrolactam antibiotics.     

Direct perfluoroalkylation of non-activated aromatic C-H bonds of phenols

A simple procedure for the perfluoroalkylation of the aromatic ring of phenols under mildly basic conditions is described. Treatment of a variety of phenols with perfluoroalkyl iodide in the presence of the radical initiator V-70L and Cs₂CO₃ provided the corresponding perfluoroalkylated products in moderate to good yields. Generally, the reaction proceeded smoothly at room temperature to yield regioselectively perfluoroalkylated products.     

Scaling and instability analyses on flame spread over liquids

Stability and scaling analyses were applied to experimental data obtained by this group and other researchers on pulsating flame spread over liquids. Data to be analyzed include recent findings of cyclic appearance of a cold temperature valley at the liquid surface-created surface-wave ahead of the spreading flame, and main-pulsation of 0.5–2 Hz and sub-pulsation of 5–10 Hz. Our stability analysis is performed to understand the mechanism of instability on the liquid surface ahead of a flame’s leading edge, which is thought of as the major cause for pulsating flame spread. The scaling analysis is performed to explore the role of four independent (gravity, surface-tension, viscose, and inertia) forces on the mechanisms of flame spread. These four forces form three independent pi-numbers: Marangoni (Ma) number, Weber (We) number, and Froude (Fr) number, all of which include the critical length scale ratio: (height of sub-surface circulation)/(horizontal length of preheated liquid surface). We combined the wave equation obtained from the stability analysis, the three pi-numbers, and the critical length scale ratio, and used them as a universal formula to describe flame spread over liquids. Using this formula, flame spread mechanism over four different types of alcohols was divided into two separate regimes: the thin liquid pool and the thick-liquid pool. For the thin liquid pool, the flame spread rate was correlated with (Fr/Ma^0.5)^−1.0, while for the thick-liquid pool it was correlated with (Fr/Ma^0.5)^−1.5. Change of flame spread pattern from the uniform to the pulsating can be described with temperature difference between the flash point and bulk liquid temperature. For the thin liquid pool this temperature difference is correlated with Ma^−0.5, while for the thick-liquid pool it is correlated with Ma⁻¹. The frequency of pulsation is correlated with We^−1.0 for the thin liquid pool, while it is correlated with We^−1.5 for the thick-liquid pool.     

Pepsinogen secretion from cultured rat gastric mucosal cells

Rat gastric mucosal cells were isolated with the aid of 0.1% collagenase and Dispase. Pepsinogen secretion from these cells was stimulated by carbachol, cholecystokinin octapeptide (CCK(S)-8) and pentagastrin, but not by histamine. Attempts to obtain a sufficient number of cells using a higher concentration of Dispase resulted in disappearance of the responses to secretagogues. However, when gastric mucosal cells thus prepared were cultured for 24 h in a CO2 incubator, they were found to respond not only to carbachol, CCK(S)-8 and pentagastrin, but also to histamine, resulting in an increase in pepsinogen secretion. The secretagogue-induced pepsinogen secretion was inhibited by its antagonist in a dose-dependent manner. These results suggest that the receptor present in chief cells for pepsinogen secretion was destroyed during the isolation procedure and regenerated during culture.