Improvement of Mechanical Properties of Machinable Glass-Ceramics through Postmachining Heat Treatments

A mica-based machinable glass-ceramic has been converted to a glass-ceramic containing cordiertie and body-centered cubic chondrodite through heat treatment at temperatures higher than that used for the crystallization of mica. The machinability is lost, microhardness increases, and the thermal expansion coefficient decreases with the change of the crystalline phase from mica to cordierite and chondrodite.     

Temperature and pressure conditions for the appropriate performance of charge and mass resolutions in balloon-borne CR-39 track detector for the heavy cosmic rays

We experimentally determined the suitable conditions of temperature and air pressure for measuring charge and mass compositions of heavy cosmic rays using CR-39 track detectors during long-duration, high-altitude balloon flights. The experiments were carried out utilizing Fe ion beams from Heavy Ion Medical Accelerator (HIMAC). Changes in the track registration sensitivity with temperature were studied at temperatures between 213 and 293 K. The charge and mass shifts around Fe ions are possibly 0.11 cu (charge unit) and 0.47 amu (atomic mass unit) at the temperature deviation between 227 and 243 K at balloon altitude. Decrease in track registration sensitivity as air pressure decreases has been observed between 13 Pa and 27 kPa. The charge and mass shifts around Fe ions are inferred to be 0.02 cu and 0.09 amu, respectively, when pressure varies between 20 and 27 kPa. During balloon flight, air pressure drops below this; therefore, care must be taken to keep the temperature and air pressure of CR-39 detectors within acceptable limits.     

Quantum Effects on Hydrogen Isotopes Adsorption in Nanopores

We have investigated the applicability of simulations and theoretical techniques for exploring the selectivities of hydrogen isotopes. We have simulated the adsorption isotherms of H₂ in an idealized carbon slit pore at 77 K by using the grand canonical Monte Carlo simulations with the Feynman-Hibbs effective potential (FH-GCMC) and the rigorous path integral method (PI-GCMC), and we obtained good agreement between the isotherms from both simulations. This suggests that FH-GCMC, which uses the approximative Feynman-Hibbs treatment, is as useful as PI-GCMC for exploring H₂ adsorption at 77 K. Moreover, we show that the ideal adsorption solution theory (IAST) can predict the selectivity of D₂ over H₂ in the interstices of single-wall carbon nanotube (SWNT) bundles at 77 K (below 0.1 MPa) very well by comparing the obtained results with the mixture adsorption FH-GCMC simulations. This indicates that IAST is also applicable to the estimation of the selectivity of D₂ over H₂ at moderate pressures and at 77 K from experimental single-component adsorption isotherms. We also demonstrate that the FH-GCMC simulation can reproduce the experimental adsorption isotherms of H₂ and D₂ in aluminophosphate AlPO₄-5 at 77 K. Finally, we analyze the selectivity of D₂ over H₂ by IAST with the experimental single-component adsorption isotherms of H₂ and D₂ at 77 K for a variety of adsorbents: AlPO₄-5, activated carbon fibers (ACFs), HiPco SWNT, and SWNHs. The selectivities predicted by the experimental adsorption data based on the results from the FH-GCMC simulations are presented and discussed.     

Preparation and Properties of Glass-Ceramics Derived from Nitrogen-Containing β-Spodumene Glasses

Crystallization of Li-Al-Si-O-N oxynitride glasses based on the β-spodumene composition and the properties of the resultant glass-ceramics have been studied. The onset of the precipitation of metastable high-quartz solid solution and its transformation to β-spodumene shift to higher temperatures with increasing nitrogen content of the oxynitride glasses. Nitrided glass-ceramics crystallized at 1200°C have negative thermal expansion coefficients, since high-quartz structure is maintained up to 1000° and 1200°C. Knoop hardness and density of the glass-ceramics increase with increasing nitrogen content. There was evidence that part of the nitrogen atoms were incorporated into the high-quartz solid-solution structure and that a small amount of the minor phase of Si₂N₂O was precipitated in highly nitrided glass-ceramics.     

Promoter/repressor system of Lactobacillus plantarum phage og1e: characterization of the promoters pR49-pR-pL and overproduction of the cro-like protein cng in Escherichia coli

Previous studies have shown that extensive damage to the medial prefrontal cortex (mPFC) of rats causes reversal learning deficits. The mPFC of rats, however, consists of several subareas that are different from each other in both cytoarchitecture and neural connectivity, suggesting a functional dissociation among the mPFC subareas. In the present study, selective lesions of the mPFC of rats were made with a specially designed microknife whose intracranial placement could be controlled stereotaxically. Restricted lesions were made to each of the 3 parts of the mPFC: the anterior cingulate area (AC) (including the medial precentral area, PrCm), the prelimbic area (PL), and the infralimbic area (IL). One week after surgery, rats were trained in an aversively motivated visual discrimination task in a novel rotating T-maze. After reaching the acquisition criterion, rats were trained in a reversal task in the same maze. No difference was found in acquisition between control and mPFC lesioned rats. However, lesions of either the PL or the IL produced a marked deficit in the reversal task. This behavioral deficit was not found in rats with lesions of the AC. The results indicate that the mPFC of rats is not essential for discrimination learning, but that each of the 2 ventral subareas of the mPFC, PL, and IL, plays a critical role in reversal learning.     

The use of transbronchial lung biopsy to establish a diagnosis of benign clear cell tumor of the lung: report of a case

Benign clear cell tumor (BCCT) is an extremely rare pulmonary neoplasm. We report herein a case of BCCT of the lung that was diagnosed by a transbronchial lung biopsy (TBLB). The findings of hematoxylin-eosin and immunohistochemistry obtained by the TBLB were consistent with a diagnosis of BCCT of the lung. Wedge resection was subsequently performed by video-assisted thoracotomy. To the best of our knowledge, this is the first reported case of BCCT diagnosed by TBLB.     

Occlusion of the posterior humeral circumflex artery: detection with MR angiography in healthy volunteers and in a patient with quadrilateral space syndrome

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of MR angiography in detecting occlusion of the posterior humeral circumflex artery and to determine if the finding is specific for the diagnosis of quadrilateral space syndrome. SUBJECTS AND METHODS: Two-dimensional fast low-angle shot MR angiography was used to image both shoulders of one symptomatic patient and six asymptomatic volunteers (10 posterior humeral circumflex arteries). RESULTS: With the arm in a neutral position, the posterior humeral circumflex arteries appeared normal on MR angiograms of all subjects. However, when the arm was in abduction, occlusion of the posterior humeral circumflex artery was seen both in the symptomatic patient and in 80% of the asymptomatic volunteers. CONCLUSION: Our data show that occlusion of the posterior humeral circumflex artery is common in asymptomatic volunteers. Thus, MR angiography has no value in the diagnosis of quadrilateral space syndrome.     

Augmentation of polysialic acid by valproic acid in early postnatal mouse hippocampus and primary cultured hippocampal neurons

We examined the effects of valproic acid (VPA) on hippocampal neurons. Prenatal VPA exposure significantly increased polysialic acid (PSA) expression in the early postnatal mouse hippocampus. Moreover, VPA treatment significantly enhanced PSA expression in primary cultured hippocampal neurons and stimulated neurite growth. Our results suggest that VPA exposure in ovo affects hippocampal development.