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Recombination centers introduced in silicon p+-n-n+structures by irradiation with 2-MeV electrons are studied by measuring minority carrier lifetime and annealing kinetics. The approximate location of these recombination centers in the forbidden gap and their densities are obtained by the thermally stimulated current method. The results identify one defect as a divacancy with an energy level of E v + 0.26 eV. Possible identities of other deep levels are discussed. The technique of minority carrier lifetime control by electron irradiation has been developed into a reliable manufacturing process for power devices.

The isolated retinal pigment epithelium-choroid of sheep was studied in vitro as a single membrane mounted in a Ussing chamber. The average potential of 40 tissue preparations was 6·3 mV. In all preparations the retina (apical) side was positive with respect to the choroid (basal) side. Changes in Na + , K + , or Ca 2+ concentration on the choroid side did not affect the tissue potential, whereas a ten-fold increase in K + concentration or Ca 2+ chelation by EGTA on the retina side decreased the potential. The potential was also decreased by 0·75 m m -phloridzin and 1·0 m m -dinitrophenol. Utilizing a glucose concentration gradient of 4 m m -choroid to 1 m m -retina side, the unidirectional glucose fluxes were found to be 883 nmol/cm 2 · hr choroid to retina and 222 nmol/cm 2 · hr retina to choroid. Both unidirectional fluxes were decreased by 65% Na + replacement with choline Cl. The retina to choroid flux was also decreased by 0·75 m m -phloridzin and 1·0 m m -dinitrophenol. The sodium dependence and inhibitor effects suggest that mechanisms of glucose transport other than simple diffusion are operative in sheep retinal pigment epithelium.

Samples of feeds fed to dairy cattle on the university farm were analyzed from 1962 to 1967 for fallout 137Cs by means of gamma-ray spectrometry. Maximum levels were observed in first-cutting alfalfa hay in 1963 (3600 pc/kg).Second and third cuttings each year were lower by factors of two to six. Levels declined each year after 1963 to barely detectable levels in mid-1967. Pasture forage or green-cut alfalfa contained concentrations of 137Cs similar to hay with the same seasonal and yearly patterns. Corn silage contained levels similar to later cuttings of hay. Grain mixes contained levels which were lower than forages by a factor of 10 in 1962-1963 but approached equal levels in subsequent years. The results indicated that sampling was much more important than radiation counting in explaining variation between sampling. The levels of 137Cs found in the feeds was readily explained in terms of observed patterns of fallout during this period.

foUNDINC is one of the early arts and undoubtedly had its origin at the time of the development of the blast furnace in the latter middle ages. It has made its greatest progress, however, since the methods of using mineral fuel in this furnace have cheapened the product of the latter so much that ninety per cent . or more of that product is now nothing more than the raw material for the production of steel . 'hhe art of founding was almost ignored by the scientific metallurgist until within comparatively few years. The developments in the manufacture of steel were so rapid and of such vast importance to the whole of mankind that practically all the labors of iron and steel metallurgists were devoted to steel, and the foundrvman was left to struggle along as best he could on the basis of his hard-earned, and sometimes contradictory, practical knowledge and experience . In the nineties of the last century was brought about a great change in this condition, for chemistry began to be applied freely in the foundry, and by its aid many facts in connection with its manufacture of cast iron were brought out . Sonic of these facts the practical men declared were not true, and the conditions of cast-iron manufacture are so complex that many are still in dispute . In 1900, the closing year of the decade referred to, T published in the American Machinist an article in which, to my mind, was made the first definite and coherent statement of the nature of cast iron, particularly in its relation to steel. The following are some quotations from this article

Pretreatment EEGs were obtained on 81 hyperthyroid patients. In order to study the effects of sex and the menopause on the incidence of EEG abnormalities, the patients were divided into three groups: 1. premenopausal females, 2. postmenopausal females, and 3. males. The highest incidence of abnormalities was found in premenopausal females, and the lowest incidence in postmenopausal females. The administration of reserpine to thyrotoxic patients increased the incidence of EEG abnormalities. Most of the records obtained 3 months to 1 year after specific antithyroid treatment with radioactive iodine were normal except for the persistence of high voltage photic responses.

The use of neutron transmutation doped (NTD) Si has become very important for processing high-voltage power devices. A simple annealing process is usually required to anneal the lattice defects caused by neutron irradiation. This is usually performed by the silicon supplier by annealing the silicon crystal at a low temperature (approximately 700°C). High-voltage power devices, however, require much higher processing diffusion temperature. In situ annealing of silicon, therefore, can occur during device processing. Furthermore, we demonstrate here that higher yield can be obtained using the in situ annealing. This improvement is due to the effectiveness and uniformity of annealing of thin wafers. The uniformity and blocking voltage distribution of high-voltage rectifiers and thyristors using crystal annealed and in situ wafer annealed NTD silicon are presented.

High-power mesa-type rectifiers were passivated with successive layers of SiO 2 and Si 3 N 4 by a low-temperature chemical vapor deposition technique. Reverse I-V characteristics, high-temperature yield, ancl blocking life test results are compared with values obtained with a polyimide coating. The high-temperature performance of the oxide-nitride passivated unit is found to be superior to the polyimide coated units. A strong correlation between the high-temperature leakage current and thermal stability of the device is noted.

Electroencephalograms were made in nine normal male and two normal female subjects before and after the ingestion of 300 μg of triiodothyronine daily for 3 days. Following the administration of the hormone, the duration of the EEG arousal response was shortened in all subjects, and responsiveness to photic stimulation was increased in five of the eleven subjects. Eight of the eleven subjects reported perceptual distortion. No change in alpha frequency was observed.

Summary Very little is known about structural changes in the central nervous system following exposure to increasedg forces. Sprague-Dawley rats were centrifuged at Ames Research Center at2.76–4.15 × g for periods ranging from 4 days to 21 months. The lateral vestibular nuclei were processed for electron microscopy and examined for evidence of structural alteration as a result of centrifugation. The number of filamentous nuclear inclusions, varicosities, and relative number of axosomatic synaptic terminals containing flattened vesicles (presumed inhibitory in function) increased in centrifuged rats. Altered mitochondria also were noted in the cell bodies of Deiters' neurons. Neuroaxonal dystrophy (NAD) was found in long-term centrifuged rats and was characterized by axons filled with reticulated mitochondria. The NAD found in the lateral vestibular nuclei of centrifuged rats is different from that seen in the dorsal column nuclei of aged mice.

A commercially developed IFA system (Electro Nucleonics, Inc.) was compared to EIA (Abbott Laboratories) and WB (Bio-Rad, Inc.) for detection of HIV-1 antibodies. Of 91 EIA negative sera tested, 76 (83.5%) were negative, and 15 (16.5%) were equivocal by IFA on initial testing. Of 156 EIA positive sera tested, 18 were equivocal by either IFA or WB and could not be directly compared. Of 138 EIA positive sera directly comparable, IFA and WB agreed 137 times (99.3% correlation). Based on these findings, the commercially developed IFA system appears to be most useful as a supplementary test, similar to WB, rather than as a screening test.

This work is directed toward support studies for the national program for the development and demonstration of in situ coal gasification processes. The objective of this work is to determine the reaction-controlling variables and reaction kinetics for the gasification of chars obtained by pyrolyzing coal in simulated underground gasification conditions. The reactions being studied and to be studied include steam-char, CO/sub 2/-char, H/sub 2/-char, the water-gas shift reaction, and the methanation reaction. In this report are presented data regarding the kinetics of the reaction of steam with chars prepared from Pittsburgh seam high-volatile bituminous coal. In addition, a reaction model is described correlating the steam-char reaction rates measured earlier for Hanna subbituminous coal with operating conditions including temperature, partial pressures of steam and hydrogen, and extent of carbon gasification. Partial results are presented and discussed for an investigation of structural parameters of Hanna char as a function of pyrolysis conditions and extent of carbon gasified.

Three commercially available neuroblastoma cell lines were analyzed to determine their ultrastructural, functional and neurochemical characteristics. The cell lines were Neuro-2a and NB41A3, derived from mouse neuroblastoma, and IMR-32, derived from a human neuroblastoma. Ultrastructurally, the neuroblastoma exhibited two major differences. Both mouse neuroblastoma cell lines contained virus-like particles, whereas the human neuroblastoma was free of virus particles. Scanning electron-microscopy revealed that the external morphology in the mouse cell lines was heterogeneous, suggesting the presence of more than one cell type, while the external morphology of the human cell line was homogeneous, suggesting the presence of a single cell type. Neurochemically, choline acetyltransferase, tyrosine hydroxylase and glutamate decarboxylase, synthetic enzymes for acetylcholine, catecholamines and γ-aminobutyric acid, respectively, were present in each cell line. Mean choline acetyltransferase activity was highest in NB41A3, but differences in this activity among the three lines were not statistically significant. Tyrosine hydroxylase activity in IMR-32 was significantly higher than in the mouse neuroblastoma cells. Glutamate decarboxylase activity was equivalent in all three cell lines. Functionally, each cell line was tested to determine its ability to form cholinergic synapses on cultured striated muscle cells. Only the IMR-32 cells formed appreciable numbers of synapses with muscle cells as detected by electrophysicological recording. The delineation of several characteristics of these three neuroblastoma cell lines will allow other investigators to choose the most appropriate of these cell lines for their studies. The heterogeneity of cell types of the mouse neuroblastoma may compromise biochemical measurements as each cell type may have different characteristics. Since only the IMR-32 form cholinergic synapses and have no more choline acetyltransferase activity than the other two cell lines, the presence of this enzyme is not a reliable marker for the ability to form synapses.

Cellular and humoral immunity were evaluated in guinea pigs after immunization with influenza virus vaccine. Guinea pigs were immunized either systemically or locally into the respiratory tract, and the humoral and cellular immunities were evaluated in serum and splenic lymphocytes (systemically) and in bronchial washings (local immunity). At a dose of influenza virus vaccine adjusted by weight equivalent to that used in human immunization, parenteral immunization led to the development of circulating antibody and to cell-mediated immunity, as determined by the inhibition of macrophage migration, in splenic lymphocytes. After local immunization with nose drops, local cellular and humoral immunity developed but there was little systemic immunologic response. After a larger dose of antigen, equivalent to 10 times the usual dose given to immunize humans, cell-mediated immunity developed in both the bronchial washing lymphocytes and the splenic lymphocytes in the parenterally immunized animals. Humoral immunity, however, maintained the same pattern as in the animals which received the lower dose of vaccine; i.e., locally immunized animals developed mainly local antibody and parenterally immunized animals developed mainly systemic antibody. The inhibition of macrophage migration activity had disappeared or was greatly reduced in both the splenic and bronchial wash lymphocytes by 28 days; however, the influenza-neutralizing antibody persisted through this time.

Although neuroaxonal dystrophy (NAD) has been examined by light and electron microscopy for years, the nature of the components in the dystrophic axons is not well understood. The present report examines nucleus gracilis and cuneatus (the dorsal column nuclei) in the brain stem of aging mice.Mice (C57BL/6J) were sacrificed by aldehyde perfusion at ages ranging from 3 months to 23 months. Several brain areas and parts of other organs were processed for electron microscopy.At 3 months of age, very little evidence of NAD can be discerned by light microscopy. At the EM level, a few axons are found to contain dystrophic material. By 23 months of age, the entire nucleus gracilis is filled with dystrophic axons. Much less NAD is seen in nucleus cuneatus by comparison. The most recurrent pattern of NAD is an enlarged profile, in the center of which is a mass of reticulated material (reticulated portion; or RP).

In studying the morphology of aging cells, it is generally concluded that different changes occur in fixed postmitotic cells as compared to those cells which divide actively throughout life. The testis appears to be an excellent model for a comparative investigation of such changes, since it contains some cells which are essentially non-dividing in adulthood (Sertoli cells and interstitial cells) as well as other cells which divide continuously in mature animals (spermatogonia and spermatocytes).We have examined, by light and electron microscopy, the testes of numerous C57BL/6J mice at ages ranging from 3 to 30 months. All tissues were fixed by vascular perfusion with paraformaldehyde and glutaraldehyde mixtures in phosphate buffer.Sertoli cells (Fig. 1) and interstitial cells (Fig. 2) in aging animals contain a large number of dense bodies (presumably lipofuscin). On the other hand, dense bodies are not seen in spermatogonia, spermatocytes or spermatids (Fig. 1).

Very little is known about the effects of altered gravitational forces on the morphology of the central nervous system. Data so far published have been at the light microscopic level. The present abstract and corresponding article (in preparation) represent initial electron microscopic observations of changes in the lateral vestibular nuclei (VL) of rats centrifuged for varying lengths of time. Several groups of rats were employed in the study. Two groups were placed on a centrifuge (4.15 g's) at weaning and removed after 4 days. One group was conceived, born and raised on the centrifuge (4.15 g's) for 1 month. Other rats were placed on at weaning and left on for up to 21 months (2.76-4.l5 g's). All the centrifuged rats were sacrificed by aldehyde perfusion immediately after removal from the centrifuge.In the rat lateral vestibular nucleus, some synaptic terminals contain spherical (S) vesicles and others flattened (F) vesicles.

Microsecond rise of electroluminescent, EL, output to greater than the steady state value for a-c sine-wave excitation has been achieved in plastic-embedded powder phosphor cells by application of an a-c burst having a dc component. The decay time for the EL flash, 7 microseconds, is somewhat longer than the rise time. The phosphor used is ZnS:Cu, Cl dispersed in a polyvinyl chloride acetate plastic and sprayed onto a conducting tin oxide-coated glass. The back electrode is a circle of evaporated aluminum 0.2 cm2in area. Electrical contact to the tin oxide is made through silver print painted onto the tin oxide-coated glass around the Al electrode. Light output from the cell is monitored by an RCA 7102 photomultiplier fitted with a cathode-follower output.