Search

L-shell X-ray emission cross sections have been measured for 1 keV electron impact on Ar, HCl and Cl2. The fluorescence yields derived from these cross sections and known Auger emission cross sections are significantly smaller than results of recent theoretical calculations of the fluorescence yields for configurations with more than one open shell. This indicates that the assumption of statistical population of the initial spectroscopic terms when calculating mean fluorescence yields is invalid.

K X-ray production in the collisions Ne+, Ne++ to SiH4; Si+, Si++ to Ne and Ar++ to SiH4 has been studied in the energy range 90-360 keV. Ar(K) and Si(K) X-rays were looked for but not observed, and the production cross sections must be less than 10-26 cm2, but Ne(K) X-rays were found and the corresponding cross section increases between 10-24 and 3*10-22 in the energy range studied, which agrees with expectations according to the electron promotion model of Fano and Lichten (1965). Comparison has been made of these ion-gas target results, with the previous ion-solid target results of Brandt and Laubert (1970) and Taulbjerf et al. (1973), and comment is made on the interpretation in terms of 'solid effects'. Within the framework of the Fano-Lichten model a rotational coupling of the 2p sigma MO to levels at or near the continuum is required to explain our observation of Ne(K) X-rays.

During proton bombardment of a copper single crystal the Balmer-β spectral line is observed. This line, at 4861 A, is considerably broadened, the lineshape has been studied as function of impact energy (10–40 keV) and angle of incidence of the protons with respect to the surface normal. The broadening is attributed to the Doppler effect. Only fast hydrogen atoms can escape from the solid surface in an excited state. The slow moving particles undergo a resonance non-radiative decay process. This is concluded from a comparison between experimental lineshapes and calculated lineshapes according to the theory of part 1 of this two-part paper. Good agreement with the experimental data is obtained when using for the strength of the radiationless de-excitation A' = 1.5 × 108 cm/sec. This value appears also to be consistent with the minimum yield in the proton intensity observed under channeling conditions.

Propranolol, a s-blocking agent, increased the permeability of the inner mitochondrial membrane to the monovalent cations potassium and sodium. It also increased the net uptake of chloride and nitrate anions, but hardly affected the uptake of acetate, phosphate or sulphate. When bound to the membranes the drug released hydrogen ions. In solutions containing potassium chloride, valinomycin plus FCCP propranolol increased the apparent buffering capacity of mitochondria. These changes are interpreted to be the result of a change in the membrane charge distribution and of perturbation of the membrane structure.

Cross sections for K-shell X-ray production in collisions of Ar with Ar, HCl and Cl2 have been measured in the energy range 0.25-2.2 MeV. These experiments show unambiguously that K-shell ionization does occur in symmetric systems with an atomic number larger than 10, under adiabatic and single collision conditions. Yet, the cross sections are so small that the results are not necessarily in contradiction with the molecular model. Observed differences in cross sections and spectra for Ar-Cl2, as compared with Ar-Ar, Ar-HCl, are speculated to be due to double scattering the Cl2 molecule. Ar-2p vacancies created in the first collision can, during collision with the second Cl-atom of the same molecule, lead to: promotion of Cl-K electrons via 2p pi -2p sigma rotational coupling; promotion of Ar-K electrons via 2p pi -1s sigma rotational coupling: the production of MO X-rays. These speculations are consistent with experimental results. A calculated cross section for K-shell ionization via 2p pi -2p sigma rotational coupling, is shown to be in good agreement with the Cl-K ionization cross section in Ar-Cl2 double scattering deduced from the experimental results.

Inelastic effects have been studied under multiple scattering conditions in ion-solid interactions. Charge state distributions of argon and chlorine ions emerging from carbon foils were measured in the energy range from 70 to 350 keV. Differences in the average equilibrium charge state of argon and chlorine at fixed velocities are observed which is explained by inner-shell vacancy production and surface neutralization. The relevance of the obtained results for surface studies with ion beams under multiple scattering conditions is discussed.

The nucleotide sequence has been determined for the first 53 bases of brome mosaic virus RNA4, the monocistronic messenger for brome mosaic virus coat protein. The sequence includes the binding site for wheat embryo ribosomes. The 5′-terminal base is a modified guanosine attached to the penultimate base through a 5′ p-p-p 5′ link. The initiating AUG codon is only 10 nucleotides from the 5′-terminus. The 13 triplets following the AUG codon correspond to the known sequence of brome mosaic virus coat protein.

Summary No “high-affinity” binding sites for Ca2+ were found in rat liver mitochondria when care was taken to exclude energy-dependent uptake of Ca2+. When respiration was not completely blocked or when preincubation was too short to drain endogenous energy stores Scatchard plots showed the presence of both low-affinity and apparent high-affinity sites. It is suggested that the latter do not represent true binding sites but result from energy-dependent accumulation of Ca2+.

The effects of propranolol on mitochondrial ion fluxes have been studied in oscillatory conditions in the presence of potassium plus valinomycin. The drug was able to decrease slightly the rate of swelling and that of passive contraction a little more. When the concentration of external salt was below 10 mM, propranolol decreased the extent of swelling; above 15 mM it was increased by the drug. The inhibition of contraction was abolished by nigericin or raised pH and was less evident with ATP rather than succinate as the source of energy. Propranolol only slightly affected the oxidative phosphorylation and latent ATPase activity of mitochondria. At low concentrations of salts the rate of valinomycin-stimulated respiration and ATPase activity were both inhibited. At higher concentrations of the salts, both were stimulated. It is suggested that the stimulation of respiration and ATPase activity result from increased ion uptake. Propranolol seems to stabilize an “energized” state, possibly by inhibiting the entry of protons, thereby retarding the equilibration of ionic gradients across the inner membrane.

Ar L-shell X-ray emission is observed in collisions of He+, C+, N+, O+, Al+, Cl+, Ti+, Fe+, Cu+ on Ar thus proving that innershell vacancies are produced during these heavy-ion-atom collisions. The cross sections for Ar L-shell X-ray emission show to be strongly dependent on the atomic number of the projectile. The data are discussed in the framework of the Fano-Lichten model for innershell excitations. Critical internuclear distances for innershell excitation are deduced from the threshold of the cross sections and compared with data from other investigators. These critical internuclear distances present a characteristic oscillation, which is correlated to the Z dependence of the geometrical sizes of the innershells involved.

The usefulness of ion‐induced x‐ray yields to detect low‐Z impurity atoms at low concentration in medium‐Z targets and to locate their lattice sites in single crystals is established in this and the paper that follows. In paper I we describe the technique used with specific reference to phosphorus and sulfur implants in germanium crystals. Particular attention was given to the origin of the different components that constitute the backgrounds in the x‐ray energy spectrum. Peak‐to‐background ratios for these two impurity signals were then determined for H and He ions in the energy region from 0.5 to 2.0 MeV. Some results for N and Ar ions were also obtained. A beam of 0.5‐MeV H+ gave optimum conditions for foreign atom location studies.

Concentrations of sulfadiazine were compared with those of sulfamethoxazole after combination treatment of sulfonamide plus trimethoprim. Sulfadiazine was used in doses of 1.6, 1.0 or 0.6 g ini, and t

In the preceding paper, Paper I, we described an analytical technique, based on ion‐induced x‐ray yields, for detecting low‐Z impurities in medium‐Z targets. In this paper, Paper II, we report the application of this method to the lattice location of impurity atoms. Two systems have been examined to test the method, viz., P and S implants in Ge single crystals. The channeling effect was applied to the phosphorus and sulfur K x‐ray yields excited by 0.5‐MeV protons. Some 93% of implanted 31P (0.7 × 1015 atoms cm−2, room‐temperature implant, 450°C anneal), were found to occupy substitutional sites; the fraction dropped to [inverted lazy s] 63% for an implant dose of 2.7 × 1015 atoms cm−2. Channeling effect results in 〈110〉, 〈111〉, and 〈100〉 directions for Ge(S), implanted at room temperature and annealed at 450°C, prescribe a preferred off‐lattice (> 0.3 A) site for the sulfur, necessarily different from the regular tetrahedral or hexagonal interstitial sites. For hot (220°C) implantation conditions, poorer...

The contamination of silicon surfaces, treated with different etching solutions is studied by proton backscattering and proton excited characteristic x-ray emission, using primary energies of 100–140 keV. Carbon, oxygen and iodine atoms were observed on the surface. A suitable etching treatment reduced the oxygen coverage to a value of 0.2 monolayer. Furthermore, by using the channelling effect, a correlation between the number of displaced silicon atoms at the surface and the oxygen coverage is demonstrated. Measurements of carbon-K emission cross sections are reported, which enable one to use the characteristic x-ray emission as a quantitative analytical tool.

The authors examined the dependence of the heat conductivity of liquid helium II, under about its saturated pressure, on the temperature and on the heat flow, in the range between 1.2°K and the λ-point. The heat conductivity depends on the heat flow in the whole temperature range mentioned, it decreases with increasing heat flow. As a function of the temperature it has a very pronounced maximum at 1.92°K. Measurements were carried out with four capillaries of different length and width. The influence of the diameter of the tube on the heat conductivity is zero for such tubes as experimented with, at temperatures of 1.4 and 1.6°K. Between 1.8°K and the λ-point there is a definite but small influence. The bearing of this experimental fact on the theory of the phenomenon is discussed. It is likely that the effect of the length of the tube on the heat conductivity, for lengths from 1.8 to 35 cm, is zero; if not, it is small and constant over the whole temperature range and for every temperature gradient.

The present work deals with a series of cross-section measurements for soft X-ray emission produced by Ar+, Ne+, H+ on Ar and Ne+. The X radiation, which is detected by a proportional counter, corresponds to vacancies in the Ar L-shell and Ne K-shell. The cross section appears several orders of magnitude smaller for proton impact than for heavy-ion bombardment, thus showing the difference in excitation mechanisms. Mean fluorescence yields are deduced from our experimental emission cross sections and the Auger “excitation” cross sections of the innershells involved. It is observed that the fluorescence yield is influenced by the mechanism for primary vacancy creation. Finally, from the energy dependence of the cross section near threshold we determine critical internuclear distances for innershell excitation.

Phospholipase A was used to evaluate effects of local anesthetics and related agents on mitochondrial membrane conformation by recording the onset and rate of swelling following addition of the enzyme. Promethazine, chlorpromazine, cincaine, propranolol and butacaine in 3 × 10 −5 to 2 × 10 −4 M concentrations inhibited the swelling, their potency decreasing in the above-mentioned order. Laurylamine in 5 × 10 −5 M concentration also increased the lag before onset of swelling in contrast to lauric acid, which like other anionic uncoupling agents shortened the lag. Spermine and spermidine in 10 −5 M concentrations strongly inhibited swelling, the former being more potent, while polybrene, 1,4-diaminobutane and 1,5-diaminopentane were inactive. The agents which inhibit swelling also inhibited formation of lysolecithin and free fatty acids from mitochondria under influence of phospholipase A. No inhibition was found when detergent-dispersed mitochondria served as substrate for the enzyme. These results are discussed in relation to membrane conformation and charge distribution.

We report the observation of an x-ray band which cannot be identified as a characteristic atomic x ray either of the target atoms or of the projectiles. The new x ray has been observed when 70-600-keV argon ions impinge on C, Al, Si, and Fe targets. We attribute this x ray to a radiative filling of a vacancy in the $2p\ensuremath{\pi}$ orbital of the Ar-Ar system during the collision.

Addition of calcium to a suspension of sarcotuhular membrane fragments in the presence of MgCl2 and ATP caused a drop in pH followed by a rise. The pH cycle could be obtained several times by sequential additions of calcium. Addition of Triton X—100 caused similar pH changes, which were substantially slower in the absence of magnesium. During the pH drop phase an increased rate of inorganic phosphate liberation was observed, during the pH rise phase production of ammonia was demonstrated. The pH events are explained by the combined action of three enzyme activities —ATP phosphohydrolase (E.C. 3.6.1.3), ATP:AMP phosphotransferase (E.C. 2.7.4.3) and AMP aminohydrolase (E.C. 3.5.4.6). The highest specific activity of AMP aminohydrolase was found in the sarcotubular membrane and ‘light’ membrane fractions. Accumulation of calcium in conditions where binding by mitochondria was excluded, was used as a biochemical marker for sarcotubular membranes. These findings are discussed in relation to pH changes observed in muscular activity and as a mechanism of preventing excessive drops in muscular intracellular pH.

THE APPLICATION OF A DECISION-MAKING MODEL TO HISTORICAL DATA, by W.E. SARIS and I.N. SARIS-GALLHOFER During the preparatory phase which preceded the Cambrai peace agreement concluded in 1529 between Francis I and Charles Quint, the latter corresponded secretly with his aunt, Margaret of Austria regent of the Netherlands, about the nature and importance of what was at stake in the coming negotiations. What claims should be presented to the adversary ? What strategy should they adopt in the negotiations, bearing in mind the chances that their various demands had of being met ? At what point should they make their offers ? At the start or not until the peace conference ? On the basis of information gleaned from this secret correspondence, the object is to discover whether the Emperor and the regent of the Netherlands reached their decisions by means of a rational process. An attempt is made to prove this using a mathematical model. Since the documents revealed that the Emperor and Margaret of Austria were aiming at optimum gains, the model used must be based on the maximisation of utility : the criterion of a rational decision is defined in this model by the choice of the optimum strategy. [Revue française de science politique XXV (3), juin 1975, pp. 473-501.], L'APPLICATION D'UN MODÈLE DE DÉCISIONS A DES DONNÉES HISTORIQUES, par W.E. SARIS et I.N. SARIS-GALLHOFER Au cours de la phase préparatoire à la paix de Cambrai, conclue en 1529 entre François 1er et Charles-Quint, ce dernier et sa tante, Marguerite d'Autriche gouvernante des Pays-Bas, échangent une correspondance secrète sur la nature et l'ampleur des enjeux de la négociation à venir. Quelles revendications présenter à l'adversaire ? Quelle stratégie de négociation adopter en tenant compte des probabilités de satisfaction des différentes demandes ? A quel moment fera-t-on les offres ? Dès les préliminaires ou seulement à la conférence de paix ? A partir de données extraites de cette correspondance secrète, il s'agit de savoir si l'Empereur et la gouvernante des Pays-Bas prirent leurs décisions d'une manière rationnelle. La preuve est tentée à l'aide d'un modèle mathématique. L'étude des documents ayant révélé que l'Empereur et Marguerite d'Autriche tâchaient d'obtenir un gain optimal, il faut recourir à un modèle qui se fonde sur la maximalisation de l'utilité : le critère d'une décision rationnelle est défini dans ce modèle par le choix de la stratégie optimale. [Revue française de science politique XXV (3), juin 1975, pp. 473-501.] at optimum gains the model used must be based on the maximisation of utility the criterion of rational decision is defined in this model by the choice of the optimum strategy Revue fran aise de science politique XXV 3) juin 1975 pp 473-501., Saris W.E., Saris-Gallhofer I.N. L'application d'un modèle de décision à des données historiques. In: Revue française de science politique, 25ᵉ année, n°3, 1975. pp. 473-501.

The lattice sites of Ar implanted into Fe and Ni crystals are determined using the channeling technique in combination with proton induced characteristic X-ray emission. The results show that at least 90% of the implanted Ar atoms occupy random sites, which is consistent with hyperfine interaction measurements of Devare and De Waard.

Significant discrepancies between Ar L-shell fluorescence yields as determined from total cross sections and from spectral measurements in Ar-Ar collisions are shown not to be due to an error in the measured X-ray cross sections, as was suggested by Fortner and Garcia (1973). Discrepancies originate from ambiguities in identifying the atomic states involved in their spectral method.