"Intrinsic" acceptor ground state splitting in silicon: an isotopic effect.

One of the oldest open questions in semiconductor physics is the origin of the small splittings of the neutral acceptor ground state in silicon which lead to a distribution of doublet splittings rather than the fourfold-degenerate state of Gamma(8) symmetry expected in the absence of perturbations. Here we show that these acceptor ground state splittings are absent in the photoluminescence spectra of acceptor bound excitons in isotopically purified 28Si, demonstrating conclusively the surprising result that the splittings previously observed in natural Si result from the randomness of the Si isotopic composition.

X-ray standing wave analysis of the effect of isotopic composition on the lattice constants of Si and Ge.

The x-ray standing wave (XSW) technique is used to measure the isotopic mass dependence of the lattice constants of Si and Ge. Backreflection allows substrates of moderate crystallinity to be used while high order reflection yields high accuracy. The XSW, generated by the substrate, serves as a reference for the lattice planes of an epilayer of different isotopic composition. Employing XSW and photoemission, the position of the surface planes is determined from which the lattice constant difference Deltaa is calculated. Scaled to DeltaM = 1 amu we find (Deltaa/a) of -0.36x10(-5) and -0.88x10(-5) for Ge and -1.8x10(-5) and -3.0x10(-5) for Si at 300 and 30 K, respectively.

The activation of molecular oxygen by horseradish peroxidase with sodium sulfite.

Horseradish peroxidase (HRP) utilizes molecular oxygen (O2) with sodium sulfite (Na2SO3) to oxidize thioanisole and styrene at the exterior of the heme pocket.

Biomechanics of cervical tooth structure lesions and their restoration.

OBJECTIVE: The purpose of this study was to evaluate photoelastically the effects of a cervical tooth structure lesion and its restoration on stress distribution within a tooth. METHOD AND MATERIALS: Three-dimensional composite models of a maxillary first premolar with a buccal cervical lesion were fabricated. Two types of cervical lesion were tested: one was wedge shaped and had a sharp line angle at the apex of the lesion, and the other was more rounded and saucer shaped. Vertical loads of 10 lb were applied to the unrestored and restored models at the tip of the buccal cusp, the tip of the lingual cusp, and the center of the occlusal surface. The resulting stresses within the tooth model were monitored and recorded photographically in the field of a circular polariscope arrangement. RESULTS: In the unrestored situation, stress concentrated at the apex of the lesion, regardless of the lesion configuration. However, the sharper, wedge-shaped lesion demonstrated a more severe stress concentration. In the restored situation, stress around the lesion apex and the lingual cervical lesion decreased, while stresses at the gingival and occlusal margins of the lesion increased, compared with the unrestored situation. These tendencies were most obvious when the buccal cusp was loaded. CONCLUSION: The presence of a cervical lesion changed occlusal load-induced stress distribution and concentrated stress at the apex of the lesion. The shape and dimension of the lesion governed the severity of stress concentration. Restoration of the cervical lesion relieved concentrated stress at the apex of the lesion.

[Discussion on the figure-description in the author's case with "acute alcoholic scenic complex hallucination"--against the criticism of HENRY Ey in his "Traité des hallucinations"].

1. The author formerly reported three cases with rare "scenic complex hallucinations" as acute alcoholic response. The patients experienced and stated such scenic hallucinations as incoherent dreams, if they were back to that specific circumstances; emotionally alive (anxiety) and reacted (counterattack, escape, confusion and so on) to that exact memories based on their experiences. 2. Attached is the figure that explains the detail correctly, which has been published in another article (Masuho KONUMA: On the Constitution of the Scenic Complex Hallucination in Acute Hallucinosis, CODEN: HDIZAB 37(3), 469-496, 1989 and so on). 3. HENRY EY criticized in "Traité des hallucinations" that the hallucination is only genuine in subjective experience of the patient and can not be drawn as a picture and that although the details might be described verbally, the image may be changed due to excessive explanation. He concluded that picture shown as FIG. I. is unacceptable. 4. The author has many publications on his own "dream records" and believes that subjective experiences in dreams could be expressed correctly in the form of picture. 5. The pictures show the mechanism of such hallucinations more correctly with the stories of the patients. I believe that these case reports are sufficient to let readers consent the possibilities of the mechanism.

[Effects of smeared layer on luting strength of dental cements].

Effects of smeared layer on the bond strength between dentin and dental cements were evaluated. Four surface conditions (No treatment, K-etchant, Dentin conditioner and EDTA) were prepared on the ground dentin of bovine frontal teeth. A copper tube was fixed and filled with a dental cement (zinc-phosphate cement or glass-polyalkenoate cement). A hook was embedded in the tube, with or without 1 MPa load during cementation. The bond strength was measured by a tensile test using a universal testing machine. No treatment had the largest bond strength of zinc-phosphate cement with or without load. No treatment, Dentin conditioner and EDTA had large bond strengths of glass-polyalkenoate cement with or without load; the bond strength of K-etchant was small without load and comparable to those of other surface conditions when load was applied. These results suggested that the bond strength of three surface conditions was not stronger than that of no treatment. Therefore, the elimination of smeared layer was concluded to have no advantage for increasing the bond strength between dentin and dental cements.

[Observations on mortality in selected working populations].

Mortality among employees of selected enterprises in which excellent health care programmes are carried on, was observed to evaluate employees' health levels and to establish objectives for future health care programmes. Also, these data were compared with those for all Japanese and for Japanese employees belonging to the corresponding occupational groups. Seventy-three enterprises which continuously participated in the mortality survey implemented by the Japan Research Organization of Industrial Health Care for the period between 1976 and 1980, were subjected to this study. The observed employees amounted to 3,502,580 person-years. Sex and age distributions of the employees were available for 47 enterprises and the observed employees totalled 2,598,672 person-years. The main results are as follows: Mortality rate (per 100,000) is stable between 140 and 150 throughout the observed period and the average value is 145.0. The average mortality rate for males, aged 40 to 54, is 272.6. Malignant neoplasms were the main cause of death and account for 37-38%. In second place and below are heart diseases, cerebrovascular diseases, accidents, suicide and liver cirrhosis. Malignant neoplasms, especially of the stomach, lung and pancreas, show a trend to increase, and cerebrovascular diseases and liver cirrhosis show a trend to decrease. Among heart diseases, ischemic heart disease accounts for about 40% and shows no marked fluctuation. Among cerebrovascular diseases, the relative frequency of subarachnoid hemorrhage is increasing. Comparing the mortality rates for males aged 40 to 54 by industry, "Iron, steel & nonferrous metal manufacturing" and "Electricity and gas supply" show significantly higher values, and "Finance & insurance" and "Communications" show significantly lower values than the total. The distribution of main causes of death for males, aged 40 to 54, was compared by major occupational groups using Proportional Mortality Ratio (PMR). A significantly high frequency of malignant neoplasms (especially of the stomach) is observed for "Professional & technical workers, managers and officials" and that of suicide for "Craftmen, production process workers and labourers" and that of cerebrovascular diseases (especially cerebral hemorrhage) for "Protective service workers." Standardized Mortality Ratio (SMR) for males, aged 20 to 54, from all causes of death, calculated on the basis of all Japanese males in 1978 is 0.57. SMR for this population from malignant neoplasms is 0.89.(ABSTRACT TRUNCATED AT 400 WORDS)