Corrosion behaviour of various steels and alloys in a simulated coal liquefaction environment

The corrosion behaviour of Fe-Cr, Ni-Cr and Fe-Cr-Ni alloys was studied in simulated liquefaction environments over the temperature range of 623 to 723 K. Corrosion of alloys in these environments was controlled by both sulfidation and oxidation. In the slurry, the oxygen potential was apparently higher and the corrosion rate was smaller in comparison with those in the gas phase in the solvent only environment. An oxygen-rich brown coal caused much smaller corrosion than a sub-bituminous coal. With regard to the effect of the alloy compositions, chromium content controlled the corrosion rate. The Fe-Cr-Ni austenitic alloys were the most resistant. The Fe-Cr alloys with high chromium content were fairly resistant, although they may be relatively sensitive to the variation of the environments such as temperature and H₂S content. Ni-Cr alloys of less than 20% Cr may have high corrosion rate due to their fast sulfidation. The structure of the scales formed on the alloys can be reasonably explained by the phase stability diagram of Metal-O-S system.     

Enhancement of External Quantum Efficiency of Red Phosphorescent Organic Light‐Emitting Devices with Facially Encumbered and Bulky PtII Porphyrin Complexes

An enhancement in the external quantum efficiency (QE) of red phosphorescent organic light‐emitting devices (OLEDs) by using facially encumbered and bulky meso‐aryl substituted Pt^II porphyrin complexes is demonstrated. The maximum external QEs of phosphorescent OLEDs doped with the facially non‐encumbered Pt^II porphyrin complex 1 [5,15‐bis[4‐(4,4‐dimethyl‐2,6‐dioxacyclohexyl)phenyl]‐2,8,12,18‐tetrahexyl‐3,7,13,17‐tetramethylporphyrin platinum(II )], the facially encumbered Pt^II porphyrin complex 2 [5,15‐bis(2,6‐dimethoxyphenyl)‐2,8,12,18‐tetrahexyl‐3,7,13,17‐tetramethylporphyrinato platinum(II )], the Pt^II porphyrin complex 3 that bears bulkier 3,5‐di‐tert‐butylphenyl substituents [5,15‐bis(3,5‐di‐t‐butylphenyl)‐2,8,12,18‐tetrahexyl‐3,7,13,17‐tetramethylporphyrin platinum(II )], and the “doubly‐decamethylene‐strapped” Pt^II porphyrin complex 4 were 1, 4.2, 7.3, and 8.2 %, respectively. The trend of increasing QE values in the order of 1 < 2 < 3 < 4 may be related to facial encumbrance and steric bulkiness of meso‐aryl substituted Pt^II porphyrin complexes. Especially, in the case of the Pt^II porphyrin 4 , it is considered that the “double straps” play an important role in restricting rotational freedom of the meso‐aryl substituents. The triplet excited‐state lifetimes for Pt^II porphyrins 1 – 4 in OLEDs at an injection current density of 0.55 mA cm^–2 were 80, 103, 140, and 152 μs, respectively. We believe that the trend of increasing triplet lifetime in going from 1 to 4 is correlated with suppressing non‐radiative decay.     

High-power red beam generation by frequency-doubling of a Nd:YAGlaser

This letter reports the generation of 6.1 W of red laser radiation by frequency-doubling a Nd:YAG laser operating at a wavelength of 1.319 μm with a KTP crystal. The conversion efficiency and the stability of the red output power were both improved through the suppression by means of a thin etalon of two-wavelength operation in the 1.3-μm region     

Freeze-drying process of biological specimens observed with a scanning electron microscope

A pit membrane was observed with a cryo-SEM during the course of dehydration at low temperatures. The freeze-drying process of sea-urchin eggs and parenchyma cells of higher plants was also examined with this microscope. Conditions for observation of frozen specimens in the native state were discussed on the basis of morphological studies of alterations such as shrinkage or deformation which appeared during the freeze-drying process.     

L/N-Type Calcium Channel Blocker Cilnidipine Added to Renin-Angiotensin Inhibition Improves Ambulatory Blood Pressure Profile and Suppresses Cardiac Hypertrophy in Hypertension with Chronic Kidney Disease

Ambulatory blood pressure (BP) and heart rate (HR) profile are proposed to be related to renal deterioration and cardiovascular complication in hypertension and chronic kidney disease (CKD). In this study, we examined the beneficial effects cilnidipine, a unique L/N-type calcium channel blocker (CCB), in addition to renin-angiotensin system inhibitors, on ambulatory BP and HR profile, as well as cardiorenal function in hypertensive CKD patients. Forty-five patients were randomly assigned to the cilnidipine replacement group (n = 21) or the control CCBs group (n = 24) during a 24-week active treatment period. Although clinical BP values were similar in the cilnidipine and control CCBs groups after the treatment period, the results of ambulatory BP monitoring showed that the 24-h and daytime systolic BP levels in the cilnidipine group were significantly lower compared with the control group after the study. Furthermore, the left ventricular mass index (LVMI) was significantly decreased in the cilnidipine group compared to the control group after the study (LVMI, 135.3 ± 26.4 versus 181.2 ± 88.4, p = 0.031), with a significant difference in the changes in the LVMI between the cilnidipine and control groups (change in LVMI, −12.4 ± 23.7 versus 26.2 ± 64.4, p = 0.007). These results indicate that cilnidipine is beneficial for the suppression of pathological cardiac remodeling, at least partly, via a superior improving effect on ambulatory BP profile compared with control CCBs in hypertensive CKD patients.     

Use of micromanipulator for continuous observation of frozen samples by cryoscanning electron microscopy and freeze replicas

Our previous report described how a new cryoscanning electron microscope (cryo-SEM) allowed for continuous observation of certain areas of any particular frozen sample, first, by cryo-SEM and, after dissolution of the sample, by freeze replication using a transmission electron microscope. However, the latter procedure made continuous observation of individual areas which were selected by cryo-SEM impossible, because the selective withdrawal of replicas, containing the desired areas could not be accomplished. Here we report how this problem was resolved using a cryo-SEM equipped with a micromanipulator. Specimen surfaces, including areas of interest, were cut out by a thin needle attached to the micromanipulator while under observation with the SEM. Replicas from the cut areas alone were withdrawn and used for the structural correspondence studies. Using this process, continuous observation of the selected areas was successfully performed.     

New estimation methods of bacterial concentration by measuring ATP changes during incubation

New estimation methods of bacterial cell concentration in samples by measurement of the increase in bacterial adenosine-triphosphate (ATP) content during incubation using a conventional firefly luminometer were established. When an Escherichia coli cell suspension was incubated in nutrient broth, the increase in the ATP content of the suspension during the incubation period followed a sigmoidal curve. The increase ratio of the ATP content of the suspension at a given period of incubation (5 hours in this study) to the initial ATP content was greater at higher initial cell concentrations. With this relationship, the initial cell concentration of a test suspension could be predicted from the measured ratio; this was called the end point method. On the other hand, the lag period in the ATP increase curve was longer at lower initial cell concentrations. A highly linear relationship was observed between the lag period and the logarithm of the initial cell concentrations. Based on this relationship, a delay method was developed for prediction. The two relationships were also observed for bacterial suspensions of Klebsiella sp., Staphylococcus aureus, Bacillus subtilis, and Pseudomonas sp. These results suggested that the two methods have the potential to estimate the bacterial cell concentration of a sample suspension.     

Measurement of solid solubility of germanium in aluminum

The solid solubility of Ge in aluminum was determined by resistivity measurement at 77 K of Al-Ge alloys annealed at various temperatures for times sufficient to complete the precipitation of the equilibrium Ge phase. The solid solubility of Ge in aluminum was found to vary from 0.252 at. pct at 533 K to 1.82 at. pct at 693 K. From the temperature dependence of the solid solubilities, the excess entropy of mixing ΔS and heat of mixing ΔH associated with the formation of solid solution of Ge in aluminum were calculated to be 2.77 R and 38.5 kJ mol^-1, respectively. Using these values of ΔS and ΔH, the maximum solid solubility of Ge in aluminum was calculated to be 2.08 at. pct at the eutectic temperature 697 K. The magnitude Δρ _Ge ⁷⁷ /Δc due to 1 at. pct impurity was determined to be 8.60 nΩm/at. pct Ge. The resistivity of Al-1.32 at. pct Ge alloys aged at 573 and 623 K was measured at 77 K to determine the time variation of the average concentrationc of the solute in the matrix during coarsening of the Ge precipitates. The value ofc, calculated using the value of Δρ _Ge ⁷⁷ /Δc, decreased linearly in accordance with the t^-1/3 law. The concentration of the solute in the matrix, in equilibrium with the Ge particle of infinite size, was determined by extrapolating thec vs t^-1/3 plot to infinite time, in excellent agreement with the above solid solubility. Formerly Graduate Student, Department of Materials Science, Tohoku University     

Studies on the anionic polymerization of methyl methacrylate with butyllithium by using perdeuterated monomer

Summary Methyl methacrylate-d₈ was polymerized by C₄H₉Li in toluene at –78°C and the resultant polymer and oligomer were studied for butyl group by ¹H NMR spectroscopy according to the precision coaxial tubing method (HATADA 1977a). A polymer and an oligomer molecule was found to have about one butyl group incorporated through the attack of C₄H₉Li on the carbonyl group as well as one terminal butyl group. The total amount of the C₄H₉Li residue introduced in both the polymer and oligomer molecules was measured to be 0.45mmol and almost corresponded to the amount of the C₄H₉Li used (0.50mmol).