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Although Au–Ge has often been used in making Ohmic contacts to GaAs, the alloying behavior of this system has not been well characterized and understood. In this paper the behavior of Au and Au–Ge layers on GaAs was investigated as a function of processing temperature (400–600°C) and time by backscattering and channeling‐effect measurements with 2‐MeV 4He ions. Scanning electron microscopy and current‐voltage evaluations were also made. Similarities are found in both systems: There is a deeply penetrating component of Au into the GaAs that remains essentially unaltered once the surface Au has been consumed; a disordered region near the surface is found, the amount of which increased with increased process times. No significant amount of Au is found on substitutional or tetrahedral interstitial sites within about 3000 A of the surface. The presence of the Ge does have a significant effect: Complete alloying occurs at lower temperatures, and Ohmic contacts are formed. Scanning‐electron‐microcope displays in...

Photoemission measurements have been made on cobalt to study major features of its electronic structure over a large energy range. In the spectral range studied ($7.4 \mathrm{eV}\ensuremath{\le}h\ensuremath{\nu}\ensuremath{\le}11.6 \mathrm{eV}$), nondirect transitions dominate. The optical density of states is determined from the photoemission and optical data. Peaks are found in the valence-band structure at about 0.3, 2.4, and 5.2 eV below the Fermi level, and no structure is found in the conduction band for $4.5 \mathrm{eV}\ensuremath{\le}E\ensuremath{-}{E}_{f}\ensuremath{\le}115 \mathrm{eV}$. The $\ensuremath{\omega}\ensuremath{\sigma}$ curve is fitted reasonably well using the optical density of states and assuming nondirect transitions. A strong similarity is found between the optical density of filled states for Co and that of Ni and Fe. Thus the optical density of states for Fe, Co, and Ni do not seem to be related via the rigid-band model. A discussion is given on these data and their relevance to other related results.

Photoemission and optical-reflectivity measurements have been carried out on palladium samples prepared and measured in vacuum of approximately 5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ Torr for $h\ensuremath{\nu}\ensuremath{\le}11.8$ eV. In addition, photoemission measurements were made on Pd samples in poorer vacuum for $h\ensuremath{\nu}=16.8 \mathrm{and} 21.3$ eV. The optical functions ${\ensuremath{\epsilon}}_{1}$, ${\ensuremath{\epsilon}}_{2}$, $\ensuremath{\omega}\ensuremath{\sigma}$, $\ensuremath{\alpha}$, and $\mathrm{Im}(\frac{1}{\ensuremath{\epsilon}})$ have been calculated from reflectivity data by Kramers-Kronig analysis. Optical transitions are found to be predominantly nondirect in the spectral range studied, although relatively weak direct (or nonconstant-matrix-element) transitions are also observed for $11.8 \mathrm{eV}gh\ensuremath{\nu}g9.8 \mathrm{eV}$. The valence-band optical density of states of Pd, deduced from photoemission and reflectivity data, has peaks at $E\ensuremath{-}{E}_{f}=\ensuremath{-}0.1 \mathrm{and} \ensuremath{-}1.1$ eV and is lacking in strong structure elsewhere. There is no evidence for a high density of states near $E\ensuremath{-}{E}_{f}=\ensuremath{-}5$ eV as in Ni, Co, Fe, and Cr. The $d$-band structures in Pd and Ag are found to be related rather well by the rigid-band model. Values for the density of states at the Fermi energy in Pd are obtained, and are found to be in reasonable agreement (within experimental accuracy) with values obtained from band calculations. A strong peak in the loss function obtained from reflectivity data is observed at $h\ensuremath{\nu}=7.5$ eV. This correlates with the strong peak observed at 6.8 eV in energy-loss measurements and is probably due to plasma resonance. Detailed analysis of the photoemission and optical data indicate that a peak in the energy-distribution curves, which appears 7.5 eV below the maximum energy in the energy distributions for $h\ensuremath{\nu}=18.6 \mathrm{and} 21.3$ eV, is due to electrons scattered by this plasma resonance.

The formation of KrF(B) and KrCl(B) has been observed from the reaction of Xe(/sup 3/P/sub 1/) with F/sub 2/ or Cl/sub 2/ in a Kr bath gas. Also ArF(B) is observed from the reaction of Kr(/sup 3/P/sub 1/) with F/sub 2/ in an Ar bath gas. The displacement of the heavy rare gas (Rg') from vibrationally excited Rg'X* by the lighter rare gas (Rg) to give RgX(B) + Rg' is suggested to explain the observations.

A 42-year-old man presented with haemoptysis of undetermined cause for five months despite thorough investigation. Exploratory thoracotomy showed there had been "silent" penetration by a chicken bone through oesophagus into the lung. A retrospective review showed that the foreign body could be seen in only four out of 54 chest roentgenograms taken.

The rate constants for XeF(B,C), XeCl(B,C), and XeI(B,C) formation from reactions of Xe(3P1) and Xe(3P2) with NF3, N2F4, NF2, CCl4, and CF3I have been measured relative to XeCl(B,C) formation from the reactions with Cl2. The XeCl(B,C) formation rate constants from Cl2 are assumed to equal the total Xe(3P2) and Xe(3P1) quenching rate constants. The dependence of the XeX* formation rate constants upon reagent for Xe(3P1) and Xe(3P2) are similar with the polyatomic reagents having considerably smaller XeX* product formation rate constants than does Cl2. The previous claim from this laboratory that the XeF(B,C) formation rate constant from NF3 was approximately equal to the total quenching rate constant is revised downward in this work.

Two patients who developed reversible renal failure during intermittent rifampicin therapy are described. Both had febrile reactions to rifampicin. The first was also found to have uraemia associated with swelling of the glomerular endothelial cells. The second developed tubular necrosis unassociated with haemolysis or shock. tubular necrosis unassociated with haemolysis or shock. The pathogenesis of the renal lesion in these two patients, as revealed by light microscopy, immunofluorescence studies and electron microscopy, is discussed.

Two patients with miliary tuberculosis developed the adult respiratory distress syndrome (ARDS). The importance of recognising the association is stressed, since miliary tuberculosis is treatable. The diagnostic problems are discussed, with special reference to the success of transbronchial lung biopsy.

The protective effect of inhaled verapamil (estimated dose 2 . 4 mg) and sub-lingual nifedipine (20 mg) against allergen-induced asthma were each assessed by the administration of calcium antagonists 30 min before bronchial provocation tests using Dermatophagoides pteronyssinus extracts on eight young perennial asthmatics. Neither drug changed the basal forced expiratory volume in one second (FEV1) or the provocation dose of allergen required to cause a 20% fall in FEV1 (PD20 . FEV1). That calcium antagonists are ineffective in preventing allergen-induced asthma suggest indirectly that mechanism other than mediator release from mast cells may also be involved.

In H2SO4 and HCl electrolytes, the amorphous Ni-20P alloy passivates in the potential range -0.3 to about 0.2 V vs.

Summary Fiberoptic bronchoscopy was performed on 65 patients suspected of having active pulmonary tuberculosis, who were ie]ther^sputum smear-negative or had no sputum to test. Bronchial aspirate was smear positive in 25 of 65 patients (38 %) ; postbronchoscopy sputum was smear positive in 15 of 40 (37 %) and there was bronchial biopsy evidence of tuberculosis in 33 of 57 (58%). Biopsy was particularly useful; it provided the exclusive diagnosis in 12% of cases. When the 3 methods were combined, a diagnosis of tuberculosis was made within 3–4 days in 42 of 65 patients (65 %). Taking culture results into consideration, we made a definitive diagnosis in 61 of 65 patients (94 %). Thirteen patients had atypical radiographic shadows and 7 had unsuspected co-existing bronchogenic carcinoma. No major complication developed after bronchoscopy. Our results are compared with those of 3 other reported series.

The effect of terbutaline infusion was studied in six patients with cardiogenic shock due to acute myocardial infarction. Terbutaline was initiated at 3 μg/kg/min, and the subsequent infusion rate was adjusted according to heart rate and blood pressure. At 3 hours after infusion, arterial pressure increased from 62 ± 13 mm Hg (mean ± S.D.) to 89 ± 13 mm Hg (P < 0.001), cardiac index increased from 1.38 ± 0.29 liter/min/m2 to 2.68 ± 0.47 liter/min/m2 (P < 0.001), and heart rate increased from 92 ± 32 beats/min to 112 ± 29 beats/min (P < 0.005). Pulmonary artery wedge pressure fell from 24 ± 7 mm Hg to 17 ± 3 mm Hg (P < 0.01), right atrial pressure fell from 12 ± 4 mm Hg to 6 ± 3 mm Hg (P < 0.005), and systemic vascular resistance fell from 1880 ± 641 dyn-sec/cm5 to 1515 ± 418 dyn-sec/cm5 (P < 0.05). In addition, urine flow increased from 4 ± 6 ml/hr to 314 ± 237 ml/hr (P < 0.05), and subjective improvement was noted in all subjects. Undesirable effects observed were hypokalemia (all subjects), supraventricular tachycardia (one subject), and ventricular ectopic beats (three subjects), which responded to potassium replacement and other treatments. All patients required prolonged maintenance infusion to maintain adequate hemodynamic and clinical response. Four patients were weaned off from maintenance therapy after a mean duration of 4.8 days and eventually were discharged from the hospital. Two patients died, one from cardiogenic shock and one from aspiration pneumonia. This preliminary study indicates that terbutaline infusion produced beneficial hemodynamic and clinical response and may be potentially useful for the management of cardiogenic shock if careful monitoring and potassium replacement are implemented.

Summary A vender developed an immediate asthmatic reaction while removing feathers from poultry using a heated colophony-based mixture. Occupational-type provocation tests confirmed that he reacted to fumes of colophony alone.

Forty patients with advanced adenocarcinoma of the lung were treated by two FAM chemotherapy schedules. Group A (20 patients) received Futraful, adriamycin, and mitomycin C, and group B (20 patients) received 5-fluorouracil, adriamycin, and mitomycin C. The response/stabilization rate was greater for group B (4 partial responses + 4 cases of stable disease) than for group A (no responders + 5 cases of stable disease), and the median survival was longer for group B (32 weeks) than for group A (22 weeks), although the differences did not reach statistical significance in either case (P greater than 0.05). Myelotoxicity was mild in both schedules. Further studies of the two FAM schemes at an escalated dose would be worthwhile.

Summary Sodium cromoglycate (SCG) powder often clumps in the presence of high humidity, making inhalation ineffective. A pressurized aerosol containing 1 mg SCG per actuation was made; and a double-blind cross-over trial in twenty-four young patients with perennial extrinsic asthma over 8 weeks showed that 2 mg of SCG aerosol was as effective as 20 mg of the powder, and almost all patients preferred using the aerosol.

The hemodynamic effects of terbutaline infusion at rates of 0.15, 0.3, and 0.45 micrograms/kg/min were studied and compared in eight patients with severe heart failure. Terbutaline infusion at 0.15 micrograms/kg/min infusion produced insignificant effects at 30 minutes. At 0.3 micrograms/kg/min infusion highly significant beneficial hemodynamic effects were observed: at 60 minutes cardiac index increased from 1.79 +/- 0.38 to 3.60 +/- 0.96 (mean +/- SD) L/min/m2 (p less than 0.0001) and stroke volume index increased from 20.1 +/- 6.2 to 36.7 +/- 13.1 ml/beat/m2 (p less than 0.0001); mean pulmonary artery wedge pressure fell from 27.5 +/0- 5.5 to 18.5 +/- 5.7 mm Hg (p less than 0.0001); systemic vascular resistance fell from 2624 +/- 586 to 1455 +/- 500 dynes . sec . cm-5/m2 (p less than 0.0001); and pulmonary vascular resistance fell from 248 +/- 84 to 150 +/- 70 dynes . sec . cm-5/m2 (p less than 0.0005). Mean arterial pressure and O2 uptake did not change significantly; however, mean heart rate increased from 93.4 +/- 22 to 103.1 +/- 26 bpm (p less than 0.005) and plasma potassium fell from 3.86 +/- 0.14 to 3.12 +/ 0.23 mEq/L (p less than 0.05). The 0.45 micrograms/kg/min infusion at 30 minutes produced no greater hemodynamic changes than that from 0.3 micrograms/kg/min. Our study suggests that intravenous terbutaline produces beneficial effects and may be useful in the acute management of severe heart failure.

A radiation resistant power junction field effect transistor has been designed. Several types of silicon planar Schottky barrier diodes have been exposed to ionizing radiation and the same phenomena are observed as on p-n junctions - increase in the fast surface state density and the build-up of a positive space charge in the oxide. Capacitance-voltage and Hall effect measurements have been made on high quality epitaxial GaAs before and after exposure to nuclear reactor radiation.

New and improved schemes for making ohmic contact to epitaxially grown GaAs have been developed and will be presented in this paper. They have been successfully applied to microwave Schottky-barrier FET's and Gunn diodes. These contacts were prepared by dc sputtering of thin Au-Ge and Au-Zn films on n- and p-type GaAs, respectively. By controlling the Ge concentration in the film, the usual balling up can be avoided and more uniform wetting obtained. Carrier concentration under the contacts was profiled by a new junction capacitance technique, and no high-resistance layer was detected under these contacts. Contact resistances of these contacts as well as ones fabricated by other techniques have been measured over a wide range of carrier concentration (1 × 1015< n < 5 × 1018/cm3; 3 × 1016< p < 2 × 1019/cm3). They range from 10-4to 10-6ohm-cm2, depending on the carrier concentration of the material. These data can be explained by a simple model in which the surface concentration of GaAs is increased by the doping effects of Ge and Zn. The surface alloyed region of these contacts was extensively investigated and characterized by scanning electron microscopy, backscattering and channeling experiments, and electrical measurements. They indicate that Au penetrates exponentially into the bulk, and a disordered layer is introduced at the surface. These can be reduced if the alloying temperature and time are kept at a minimum.

Background Transforming growth factor-β (TGF-β) and bone morphogenetic proteins (BMPs) utilize parallel and related signaling pathways, however the interaction between these pathways in bone remains unclear. TGF-β inhibition has been previously reported to promote osteogenic differentiation in vitro, suggesting it may have a capacity to augment orthopaedic repair. We have explored this concept using an approach that represents a template for the testing of agents with prospective orthopaedic applications. Methods The effects of BMP-2, TGF-β1, and the TGF-β receptor (ALK-4/5/7) inhibitor SB431542 on osteogenic differentiation were tested in the MC3T3-E1 murine pre-osteoblast cell line. Outcome measures included alkaline phosphatase staining, matrix mineralization, osteogenic gene expression (Runx2, Alp, Ocn) and phosphorylation of SMAD transcription factors. Next we examined the effects of SB431542 in two orthopaedic animal models. The first was a marrow ablation model where reaming of the femur leads to new intramedullary bone formation. In a second model, 20 μg rhBMP-2 in a polymer carrier was surgically introduced to the hind limb musculature to produce ectopic bone nodules. Results BMP-2 and SB431542 increased the expression of osteogenic markers in vitro, while TGF-β1 decreased their expression. Both BMP-2 and SB431542 were found to stimulate pSMAD1 and we also observed a non-canonical repression of pSMAD2. In contrast, neither in vivo system was able to provide evidence of improved bone formation or repair with SB431542 treatment. In the marrow ablation model, systemic dosing with up to 10 mg/kg/day SB431542 did not significantly increase reaming-induced bone formation compared to vehicle only controls. In the ectopic bone model, local co-administration of 38 μg or 192 μg SB431542 did not increase bone formation. Conclusions ALK-4/5/7 inhibitors can promote osteogenic differentiation in vitro, but this may not readily translate to in vivo orthopaedic applications.

The optical functions ${\ensuremath{\epsilon}}_{1}$, ${\ensuremath{\epsilon}}_{2}$, $\ensuremath{\alpha}$, and $\ensuremath{-}\mathrm{Im}(\frac{1}{\ensuremath{\epsilon}})$ have been deduced from reflectance data on electron-gun-evaporated Pt samples. They were obtained by two different methods: (1) the Kramers-Kroning analysis of the normal-incidence reflectance data, and (2) the analysis of reflectance at two different incident angles. The absorption coefficient $\ensuremath{\alpha}$ shows small peaks at $h\ensuremath{\nu}=0.4, 7.7, \mathrm{and} 10.5$ eV, and a broad peak centered about 4 eV. The imaginary part of the dielectric function, ${\ensuremath{\epsilon}}_{2}$, has structure at $h\ensuremath{\nu}=6.5$ and about 11 eV.

A systematic photoemission study of the electronic structure of transition and noble metals has been undertaken to enhance the understanding of ferromagnetism.1,2 Previous work on Ni1 and Fe3 and our current results on Co indicate the presence of a large maximum in the optical densities of states about 5 eV below the Fermi level. This peak is in strong disagreement with the predictions of conventional energy‐band theory. In order to determine whether this peak is associated with ferromagnetism, a study of Pd and Pt was undertaken. Band theory suggests that their electronic structure will be similar to that of Ni. In the present Pd and Pt studies, no density of states peak is found near −5 eV. Rather in the energy range −5≤E−Ef≤0, the Pd and Pt optical densities of states are found to be closely related to that of Ag4 via the rigid‐band model. Available optical reflectivity data confirm the photoemission results. From these experiments, it is concluded that an optical‐density‐of‐states peak appears at abou...