Direct growth of CdTe on (100), (211), and (111) Si by metalorganic chemical vapor deposition

CdTe epilayers were grown directly on (100), (211), and (111) silicon substrates by metalorganic chemical vapor deposition (MOCVD). The crystallinity and the growth orientation of the CdTe film were dependent on the surface treatment of the Si substrate. The surface treatment consisted of exposure of the Si surface to diethyltelluride (DETe) at temperatures over 600°C prior to CdTe growth. Direct growth of CdTe on (100) Si produced polycrystalline films whereas (lll)B single crystals grew when Si was exposed to DETe prior to CdTe growth. On (211) Si, single crystal films with (133)A orientation was obtained when grown directly; but produced films with (211)A orientation when the Si surface was exposed to DETe. On the other hand, only (lll)A CdTe films were possible on (111) Si, both with and without Te source exposure, although twinning was increased after exposure. The results indicate that the exposure to a Te-source changes the initial growth stage significantly, except for the growth on (111) Si. We propose a model in which a Te atom replaces a Si atom that is bound to two Si atoms.     

Characterization of interface stress at InGaPAs/GaAs by cr-related luminescence line in GaAs

The interface stress at InGaPAs/GaAs heterostructure has been investigated using the energy shift and splitting of the Cr-related zero-phonon photoluminescence line at 0.839 eV observed in GaAs. It has been found that the GaAs substrate suffers both compressive uniaxial stress and tensile hydrostatic pressure at the InGaPAs/GaAs heterointerface. These shifts and splittings of the 0.839 eV line have been systematically examined as a function of the lattice mismatch between InGaPAs and GaAs, and the thicknesses of the epitaxial-layer and substrate. The amount of the interface stress existing at InGaPAs/GaAs heterostructure has been estimated, based on uniaxial stress data for GaAs: Cr wafers.     

Arteriovenous anastomoses in the skin of tropical cattle

As part of a general study of the vascular arrangement in the skin of cattle in tropical environments, the arteriovenous anastomoses (AVA) and other specialized vascular structures in the various skin sites of cattle were observed histologically. AVA were abundant in the skin from the scrotum, eye margin and the lower limb sites but were generally less numerous on the hairy body skin sites of cattle. Most of the AVA, especially those in the scrotal skin, were complex and tortuous S-shaped vessels, mainly located in the mid- and lower reticular layer and the mid- and lower papillary layer. The possible significance of their presence in various body sites, especially on the scrotal skin, is discussed.     

Micropuncture studies of glucose transport in the dog: mechanism of renal glycosuria

Clearance and micropuncture studies were performed in 23 dogs without glucose loading to examine the tubule mechanism of renal glycosuria. Studies were carried out in three groups of animals before and after 10% extracellular volume expansion, and administration of maleic acid in low dose at 150 mumol/kg and in high dose at 300 mumol/kg. Specific hexokinase methods were used for the determination of glucose in tubule fluid and urine. Under control conditios, glucose reabsorption occurred predominantly in the proximal tubule. In all three groups, proximal tubule reabsorption of both sodium and glucose was inhibited in the second phase, showing a good correlation between the two. In contrast, fractional urinary glucose excretion remained unchanged after volume expansion and low-dose maleic acid, indicating reabsorption of virtually all the increased glucose load at a further "distal" site. On the other hand, significant glycosuria developed after high-dose maleic acid that was a result of reduced glucose reabsorption in the distal nephron, in addition to the proximal effect. It was concluded that distal glucose transport plays a significant role in regulating urinary glucose excretion and maintains renal thershold for glucose,     

Evaluation of fecal technics for the diagnosis of cat liver fluke infection

The comparative efficiency of 5 standard technics for the detection of feline liver fluke ova in feces was evaluated. The formalin-ether technic proved superior to direct smear, sugar flotation, zinc sulfate flotation, or detergent sedimentation technics. The formalin-ether technic correctly diagnosed all Platynosomum concinnum-infected cats studied, as confirmed by necropsy findings.     

Changes in serum thyrotropin (TSH) in man during halofenate administration

Halofenate, a serum lipid-lowering agent which inhibits binding of thyroid hormone to thyroxine-binding globulin (TBG), was administered daily for 14 days to 8 hypothyroid subjects with elevated TSH concentrations as a result of incomplete thyroxine (T4) therapy. Drug administration resulted in mean increases in serum dialyzable fraction T4 (DFT4) of 52% over pretreatment levels (P less than 0.01) and in dialyzable fraction triiodothyronine (DFT3) of 26% in 7 subjects, (P less than 0.01). During halofenate treatment in these 7 subjects, serum TSH concentrations decreased significantly (mean = 39%, P less than 0.01) when DFT4 and DFT3 were increased by halofenate. In only two subjects was there a convincing temporal relationship between increased serum absolute free T4 (AFT4) and decreased serum TSH concentrations. Contrary to what would be predicted from the "free hormone hypothesis", changes in serum TSH concentration in these hypothyroid patients appeared to relate primarily to changes in the free fraction of circulating T4 and T3 (DFT4, DFT3), rather than to alterations in AFT4 or AFT3. Halofenate did not alter serum TBG binding capacity. An eighth subject did not show increased DFT4 and DFT3 during halofenate treatment despite achievement of therapeutic serum levels of the agent; in this patient, serum TSH levels rose progressively throughout the period of inadequate T4 replacement and halofenate administration. In hypothyroid patients, short-term halofenate use suggests that the pituitary-thyroid hormone feedback circuit can respond to increases in serum DFT4 and DFT3 in the absence of detactable increases in absolute free hormone concentrations.     

Morphometric study of trout gills: a light-microscopic method suitable for the evaluation of pollutant action

1. Methods are described for the morphometric estimation of parameters of the gill system of trout which are relevant to its function in gas exchange. The methods have been used with 1 mum sections viewed under the light microscope. 2. In particular the diffusion distances between water and blood are measured, which together with determinations of gill area, provide figures for the morphometrically estimated diffusing capacity. 3. The methods have been used to compare the diffusing capacity of gills from control fish and those treated in polluted waters. The concept of relative diffusing capacity (Drel) is introduced which enables comparisons to be made without the need to determine the absolute diffusing capacity. 4. Quantitative estimation of changes in relative volumes and surface areas of components of the secondary lamellae were determined, and employed to explain the possible anatomical causes of changes in Drel. 5. It is suggested that these methods can be of value in the comparison of the gills of fish treated in different waters.     

Interference of bronchographic agents with lung surfactant

Dionosil Oily (a suspension of propyliodone crystals in peanut oil and powdered tantalum were introduced into the right principal bronchi of rabbit lungs. The left lungs were used as controls. Pressure-volume characteristics of excised lungs with Dionosil Oily or peanut oil demonstrated significantly reduced compliance on inflation at a pressure of 3-4 cm H2O. These lungs also retained less air on deflation and therefore demonstrated a significantly reduced stability index. Histological sections revealed microatelectasis closely associated with crystals and/or peanut oil. Lungs with tantalum powder were not measurably influenced by the bronchographic agents. Surface balance experiments with lung surfactant and synthetic dipalmitoyl phosphatidylcholine (DPPC) demonstrated an increased minimum surface tension due to the oil suspension of propyliodone, peanut oil and particles (propyliodone and tantalum). There is good evidence that the oil suspension of propyliodone reduced the surface activity of lung surfactant in situ. Particles also may prevent the minimum surface tension from reaching relatively low values if they enter the alveoli in sufficient quantities.     

Aldosterone secretion during high sodium cerebrospinal fluid perfusion of the brain ventricles

Conscious sheep with permanent indwelling cannulae in the lateral ventricles and the cisterna magna were Na depleted and then perfused for 9 h with an artificial CSF solution. There were 3 experimental groups: Group I (n=5) received perfusion with aritifical CSF containing NA 170 MEq./1, Group II (n=7) received perfusion with artificial CSF containing Na 145 mEq./1, Group III (n=7) received no perfusion. In Group I the blood aldosterone level fell from 26.4 +/- 7.4 to 8.6 +/- 2.3 ng/100 ml by 9 h after perfusion. There was no significant change in plasma [Na] or [K], blood angiotensin II or plasma renin concentration. Blood cortisol and corticosterone levels rose. There was also a fall in post-perfusion. Group III showed no significant change in blood aldosterone concentration. Multivariate statistical analysis showed that the fall in aldosterone levels during 170 mEq./l Na perfusion could not be accounted for by changes, either alone or together, of ACTH as evidenced by alteration in blood cortisol or corticosterone, or by change of plasma [Na], [K] or renin concentrations. This data supports the hypothesis of an additional factor which may be of CNS origin being involved in the control of aldosterone secretion.