Biomedical subjects

D Takeuchi

Publications and source records attributed to D Takeuchi.

4 recordsLinked to original sources

PubMed2006

Alkene/diamond liquid/solid interface characterization using internal photoemission spectroscopy.

The photochemical attachment of 10-amino-dec-1-ene molecules protected with a trifluoroacetic acid group (TFAAD) on hydrogen-terminated single-crystalline chemical vapor deposited (CVD) diamond is characterized by total photoyield spectroscopy (TPYS), conductivity, Hall-effect, spectrally resolved photoconductivity (SPC), optical transmission experiments, and, for the first time, by in situ internal photoemission (IPE) spectroscopy applied in the spectral regime from 4 to 6 eV on the alkene/diamond (liquid/solid) heterostructures. These experiments are performed on undoped, (100) oriented, single-crystalline CVD diamond films, which contain no grain boundaries and have negligible bulk and surface defect densities. X-ray photoelectron spectroscopy (XPS) is used to investigate the chemical bonding of alkene molecules to diamond. The spectroscopic set of data shows that the photochemical reaction window of H-terminated diamond is shifted below the optical gap of diamond because of the negative electron affinity. In situ IPE experiments reveal electron emission between 4.5 and 5.2 eV. A model is introduced and discussed in which valence-band electrons are optically excited into empty hydrogen-induced surface states of diamond from where they tunnel into empty pi states of alkene molecules. We theoretically discuss the fastest attachment time to achieve a saturated TFAAD layer of about 2 x 10(14) cm(-)(2) on diamond, which is experimentally detected to be 7 h. In the case of direct optical electron excitations from diamond, the bonding efficiency will be one TFAAD molecule attachment arising from about 1600 emitted electrons.

Alkenes↗

PubMed2000

Corneal abrasions associated with pepper spray exposure.

Pepper spray containing oleoresin capsicum is used by law enforcement and the public as a form of nonlethal deterrent. Stimulated by the identification of a case of a corneal abrasion associated with pepper spray exposure, a descriptive retrospective review of a physician-maintained log of patients presenting to a jail ward emergency area over a 3-year period was performed. The objective was to give some quantification to the frequency with which an emergency physician could expect to see corneal abrasions associated with pepper spray exposure. Of 100 cases of pepper spray exposure identified, seven patients had sustained corneal abrasions. We conclude that corneal abrasions are not rare events when patients are exposed to pepper spray and that fluorescein staining and slit lamp or Wood's lamp examination should be performed on all exposed patients in whom corneal abrasions cannot be excluded on clinical grounds.

Adolescent↗

PubMedDate not supplied

Evaluation of right ventricular performance long after the atrial switch operation for transposition of the great arteries using the Doppler Tei index.

Right ventricular (RV) dysfunction may occur in patients after the atrial switch operation for d-transposition of the great arteries (d-TGA) and can be an important complication. Noninvasive assessment of RV function using echocardiography is necessary for following up these patients. We evaluated RV function using the Doppler Tei index (RV Tei index). The RV Tei index measures the ratio of total time intervals in isovolumetric contraction and relaxation to the ejection time. The subjects consisted of 33 patients who had undergone the atrial switch operation for d-TGA (the atrial switch group) (mean age, 21 +/- 4 years), 10 patients with pulmonary artery stenosis after the arterial switch operation for d-TGA (the arterial switch group) (mean age, 17 +/- 1 years), and 10 patients with a normally structured heart as a control group (mean age, 26 +/- 7 years). The RV Tei index (0.65 +/- 0.16) was significantly higher in the atrial switch group than in the arterial switch group (0.29 +/- 0.07) and the control group (0.29 +/- 0.01) (p < 0.05). The fractional area change of the RV obtained from the four-chamber view in the atrial switch group showed a significant negative correlation with the RV Tei index (r = -0.58, p < 0.01). The RV Tei index increased with increasing severity of the NYHA functional class. In the moderate/severe tricuspid regurgitation group, it was significantly higher than in patients with none/trivial tricuspid regurgitation. We conclude that the RV Tei index is useful for evaluating RV junction long after the atrial switch operation for d-TGA.

Adolescent↗

PubMedDate not supplied

An epidemiological study of neurasthenia in Chinese-Americans in Los Angeles.

This study examined the prevalence and clinical features of ICD-10-defined neurasthenia (NT) in Chinese-Americans and its relations to other psychiatric disorders. In this community epidemiological survey, the enhanced Composite International Diagnostic Interview [CIDI], with a supplemental NT module, was administered to 1,747 Chinese-Americans, selected with a stratified cluster sampling method. The SCL-90-R was also used for measuring psychiatric morbidity and symptoms. Dimensions of social stress and social support were measured by established instruments. A total of 112 ICD-10 NT subjects (6.4%) were identified. Of these, 63 (56.3%) did not experience any current and lifetime DSM-III-R diagnoses, yielding a 12-month or lifetime prevalence rate of "pure" NT of 3.61%. This rate was much higher than any of the other psychiatric disorders in this sample. Compared with normal subjects, "pure" NT subjects had significantly higher SCL-90-R total and factor scores, experienced more psychosocial stress, and perceived less social support (P < .05 or .01). Compared with subjects with depression and anxiety disorders, "pure" NT cases reported significantly less SCL-90-R psychological symptoms (P < .05 or .01), but had a strikingly similar elevation in the somatization subscale score. These data suggest that NT is a distinctive clinical condition overlapping only partially with the other better recognized diagnostic entities. In view of its high prevalence and the salience of its impact on the health of those afflicted, it is imperative that concerted research efforts be made to further elucidate the temporal stability, natural course, and outcome of such a condition.

Adolescent↗