Synthesis of TiB2 powder from a mixture of TiN and amorphous boron

TiB₂ powder was synthesized by solid state reaction using amorphous boron and TiN as a source of titanium. The TiB₂ formation did not occur at all in a nitrogen atmosphere even at 1400° C. TiB₂ formed above 1100° C in argon and hydrogen atmospheres. The only crystalline phase of TiB₂ powder was favourably synthesized at 1400° C for 360 min in an argon atmosphere from a starting powder with a composition containing excess boron (B/Ti = 2.2). The synthesized powder was well dispersed and had a particle size of 0.5 to 2 µm. The powder activity was evaluated by sintering at 4 G Pa and 1300 to 1600° C for 15 min.     

Decreased baroreflex sensitivity in patients with stable coronary artery disease is correlated with the severity of coronary narrowing

Although studies have shown that arterial baroreflex sensitivity (BRS) is decreased in patients with acute myocardial infarction, BRS changes in patients with stable coronary artery disease (CAD) have not been studied extensively. We assessed BRS by the phenylephrine method in 55 normotensive and nondiabetic patients with chronic effort angina, old myocardial infarction, or both. The control group consisted of 24 age-matched patients without coronary lesions. To identify factors that determine BRS in stable CAD, we performed multivariate analysis using age, sex, left ventricular ejection fraction, pulmonary artery wedge pressure, resting systolic blood pressure, resting heart rate, the number of stenotic coronary arteries, history of myocardial infarction, and the presence or absence of angina pectoris as variables. BRS was significantly lower in patients with CAD than in control subjects (5.9 +/- 2.9 vs 6.9 +/- 2.4 ms/mm Hg, p < 0.05). In patients with CAD, BRS was inversely correlated with age, the resting heart rate, and the number of stenotic coronary vessels (p < 0.001, p < 0.005, and p < 0.005, respectively), but was independent of other clinical parameters, including the history of myocardial infarction. In control subjects, BRS was significantly correlated only with age. These results indicate that BRS is decreased in patients with stable CAD, and this decrease is correlated with the extent and severity of coronary narrowing.     

Pitfall in 201Tl-99mTc subtraction scintigraphy: a case of 99mTc-pertechnetate uptake in a parathyroid hyperplasia]

201Tl-99mTc subtraction scintigraphy has been recognized as a useful procedure in the preoperative localization of hyperfunctioning parathyroid glands. We experienced a case which showed 99mTc-pertechnetate uptake in a parathyroid hyperplasia. This case warned us to focus a lot of attention on the detection for preoperative localization. There has been no such case reported in the previous Japanese literatures. Hypervascularity and thick fibrous capsule presumed explanation for a rare case of marked pertechnetate uptake into a parathyroid hyperplasia.     

A preparation and polymorphic relations of sodium iron oxide (NaFeO2)

The formation of α-NaFeO₂ and β-NaFeO₂ below 700°C was found to depend strongly on the structure of starting iron oxide; α-Fe₂O₃ with hcp of oxygen yielded β-NaFeO₂ with hcp and γ-Fe₂O₃ with ccp of oxygen yielded α-NaFeO₂ with ccp by a reaction either with Na₂CO₃ or Na₂O₂. The doping of Na-ions into the γ-Fe₂O₃ structure and its rapid change to α-NaFeO₂ were observed. The transformation from the metastable β-NaFeO₂ to the stable α-form was very much sluggish in the solid state, but it was accelerated by the presence of the liquid Na₂O₂.     

Formation of non-graphitizable isotropic spherulitic carbon from poly-divinylbenzene by pressure pyrolysis

Isotropic spherulites of carbon stable at 2000° C were synthesized by the pressure pyrolysis of divinylbenzene polymer sealed in a capsule. The morphology of the synthesized carbon was pressure and temperature dependent being influenced by the state of polymerization of the starting polymer. Using a polymer prepared at atmospheric pressure and 150° C without catalyst, isolated spherulitic carbon was formed at 700° C and pressures of 1000 to 1250 kg cm^–2. These spherulitic carbons were optically isotropic, hard and non-graphitizable after heat treatment at 2000° C. Such carbons originate in the co-existence of higher and lower molecular weight products of pressure pyrolysis and the survival cross-linkages in the original polymer.     

Nonpeptide angiotensin II receptor antagonists. Synthesis and biological activity of potential prodrugs of benzimidazole-7-carboxylic acids

In order to improve the oral bioavailability (BA) of 2-butyl-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimid azole - 7-carboxylic acid (3: CV-11194) and 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4- yl]methyl]-1H-benzimidazole-7-carboxylic acid (4: CV-11974), novel angiotensin II (AII) receptor antagonists, chemical modification to yield prodrugs has been examined. After selective tritylation of the tetrazole rings in 3 and 4, treatment of N-tritylated benzimidazole-7-carboxylic acids (6, 7) with a variety of alkyl halides, followed by deprotection with hydrochloric acid, afforded esters of 3 and 4. Mainly 1-(acyloxy)alkyl esters and 1-[(alkoxycarbonyl)oxy]alkyl esters, double ester derivatives, were synthesized. Their inhibitory effect on AII-induced pressor response in rats and oral BA were investigated. (Pivaloyloxy)methyl and (+/-)-1-[[(cyclohexyloxy)-carbonyl]oxy]ethyl esters of 3 and 4 showed marked increases in oral bioavailability which significantly potentiated the inhibitory effect of the parent compounds on AII-induced pressor response. Among them, (+/-)-1-[[(cyclohexyloxy)carbonyl]oxy]ethyl 2- ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimida zole- 7-carboxylate (10s, TCV-116) was selected as a candidate for clinical evaluation.     

Material-binding peptide application--ZnO crystal structure control by means of a ZnO-binding peptide

Recently, a zinc oxide (ZnO)-binding peptide (ZnOBP) has been identified and has been used to assist the synthesis of unique crystalline ZnO particles. We analyzed the influence of ZnOBP on the crystal growth of ZnO structures formed from zinc hydroxide. The addition of ZnOBP in the hydrothermal synthesis of ZnO suppressed [0001] crystal growth in the ZnO particles, indicating that the specificity of the material-binding peptide for specific inorganic crystal faces controlled the crystal growth. Furthermore, the dipeptides with a partial sequence of ZnO-binding "hot spot" in ZnOBP were used to synthesize ZnO particles, and we found that the presence of these dipeptides more strictly suppressed (0001) growth in ZnO crystals than did the complete ZnOBP sequence. These results demonstrate the applicability of dipeptides selected from material-binding peptides to control inorganic crystal growth.