The oxidation mechanism of dimethylamine borane (DMAB) as a reductant for an electroless deposition
process was studied by an ab initio molecular orbital method. Two types of reaction pathways, via either
three-coordinate borane molecules obtained by primary dehydrogenation reactions, or five-coordinate ones
by primary additions of OH- for the oxidation of the DMAB, were examined. While the former pathway
corresponds to the general oxidation mechanism of the reductant proposed by Meerakker, the present theoretical
results support the latter one. Furthermore, it was clarified that an electron emission occurs when OH- adds
to the four-coordinate compounds, which agrees with the Meerakker's mechanism. Results of the normal-mode analyses showed that the five-coordinate compounds are the transition states. The optimized geometries
of monoanion five-coordinate molecules are nearly bipyramidal. The charge and spin-population analyses
indicated that the axial bondings in the five-coordinate compounds are stabilized by the three-center three- or
four-electron bondings. During the oxidation reaction of the DMAB, the change in the net charge of B is
much smaller than that in the formal oxidation number, which is due to a great covalence. The existences of
the five-coordinate borane molecules, which are first clarified by the present study, could be the key points
of the catalytic activities of the deposited metals.
This study aimed to evaluate the relationship between timed up-and-go (TUG) test time and changes in frailty status in a longitudinal cohort study of rural Japanese older adults. Patients and Methods: This prospective cohort study included 545 community-dwelling older adults. Initial and 2-year follow-up surveys were conducted. We compared the number of the Japanese version of the Cardiovascular Health Study components during the follow-up period and classified the participants into three groups: the favorable change, unchanged as prefrail, and unfavorable change groups. Associations between changes in frailty status and TUG time in the first survey were examined. The predictive ability of the TUG test was determined using the receiver operating characteristic (ROC) curve.
Results:The favorable change group comprised 315 individuals (57.8%), the unchanged as prefrail group 105 (19.2%), and the unfavorable change group 125 (22.9%). TUG time was associated with the favorable and unfavorable changes after adjustment for covariates (OR 0.79, 95% CI 0.68-0.92, P=0.001 and OR 1.27, 95% CI 1.09-1.49, P=0.002). The ROC curve of TUG time as a predictor of unfavorable changes showed an area under the curve of 0.59. A cut-off point of TUG was calculated as 6.3 s with 49.6% sensitivity and 66.0% specificity. Conclusion: TUG time in the first survey was significantly associated with changes in frailty status 2 years later. However, its predictive value as a stand-alone test is limited and has the potential to predict future changes in the frailty status in older adults in combination with other tests.
A tritium burning experiment is conducted in order to investigate the enhancement of the neutron production rate in an inertial electrostatic confinement fusion (IECF) facility. The facility is designed to be shielded from the outside for tritium safety, and a getter pump is used for evacuating the vacuum chamber and feeding the fuel gas. A D-T gas mixture with 93% deuterium and 7% tritium is used, and its neutron production rate is measured to be 5-8 times more than that of pure deuterium gas. Moreover, the results show good agreement with a simplified theoretical estimation of the neutron production rate. After the tritium burning, the exhausted fuel gas undergoes a tritium recovery procedure through a water bubbler device. The amount of gaseous tritium released by the developed IECF facility after the tritium burning is verified to be much less than the threshold set by regulations.
Orthopantomography for dental X-ray examinations is a kind of tomography which has a special characteristic different from any other tomographic methods. A comparative study of radiographic images formed by ordinary tomographic equipment with the attachment of slits devised by the authors and images produced by orthopantomography is presented.As a result of comparing image-formation in orthopantomography with that of ordinary tomography using the same objects, (1) hardly any blur was observed inside the contours of the orthopantomographic image, (2) a very slight blurring effect of orthopantomography was observed on the slit side, (3) the slit played an important role in limiting the tomographic effect, and (4) consequently, orthopantomography may be considered as a very special type of tomography in the presence of slits.
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