Showing papers by "Ben-Gurion University of the Negev published in 1974"

Method and apparatus for generating power utilizing pressure-retarded osmosis

Abstract: A method and apparatus are described for generating power by utilizing pressure-retarded-osmosis. A first liquid having a relatively high osmotic pressure is introduced at a relatively high hydraulic pressure into a first pathway in which it contacts one face of a semi-permeable membrane, and a second liquid having a lower osmotic pressure is introduced at a lower hydraulic pressure into a second pathway in which it contacts the opposite face of the membrane. At every point in the two pathways, the hydraulic pressure difference between the liquids on the opposite faces of the membrane is maintained at a value which is less than the osmotic pressure difference between the liquids. Part of the second liquid passes by pressure-retarded-osmosis through the semi-permeable membrane, forming a pressurized mixed solution of greater volume than that of the first liquid introduced into the first pathway. The potential energy stored in the pressurized mixed solution is then converted into useful energy, such as electrical or mechanical power. According to a further feature included in some of the described embodiments, after the potential energy stored in the pressurized mixed solution is converted into useful energy, the first and second liquids are recovered by separating from the mixed solution a quantity of the second liquid equal to the quantity which passed through the membrane, the original temperatures of the so-recovered first and second liquids are restored, the original hydraulic pressure difference is reapplied between the recovered first and second liquids, and the recovered first and second liquids are then recycled through the first and second pathways.

Delay in the Detection of Cancer: A Review of the Literature

Abstract: The Consequences of Delay It would be easy to compile an impressive list of quotations testifying to the importance of cutting down the delay which precedes therapeutic action for cancer patients. Dominant professional opinion tends to coincide with common sense in arguing that the earlier the patient gets to the therapist, the more likely is his life to be saved. Thus, for example, Wiggins et al ’°’ estimated that the overall five-year cancer survival rate of 25 percent in upstate New York could be doubled if all

Elastic and magnetoelastic properties of polycrystalline rare-earth-iron Laves compounds

Abstract: Ultrasonic-sound velocity measurements have been used in order to determine the elastic moduli of polycrystalline rare-earth-iron Laves compounds $R{\mathrm{Fe}}_{2}$ ($R=\mathrm{Ce}, \mathrm{Gd}, \mathrm{Tb}, \mathrm{Dy}, \mathrm{Dy}, \mathrm{Ho}, \mathrm{Er}$) and Y${\mathrm{Fe}}_{2}$ between 4.2 and 300 K. The $\ensuremath{\Delta}E$ effect of these compounds was determined in external magnetic field up to 25 kOe. No saturation was reached at this field in Dy${\mathrm{Fe}}_{2}$ and Tb${\mathrm{Fe}}_{2}$. The anomalies in the elastic behavior of Ce${\mathrm{Fe}}_{2}$ and Ho${\mathrm{Fe}}_{2}$ were interpreted in terms of changes occurring in their magnetic structure. The results reveal the high sensitivity of the elastic constants to such changes.

Nitrate reductase as a product-inducible enzyme.

Abstract: Nitrite is a very effective inducer of nitrate reductase. Nitrate induces the enzyme in darkness only upon addition of suitable sources of reducing equivalent which permit the formation of nitrite; nitrite itself brings about induction of the enzyme in darkness without supplementation of exogenous reducing cofactors. Inhibition of constitutive nitrate reductase by tungstate prevents induction of the enzyme by nitrate but not by nitrite. Since nitrate induces the enzyme only under conditions allowing production of nitrite while the induction capacity of nitrite is free of this constraint, nitrate reductase be considered a product-inducible rather than a substrate-inducible enzyme. The ability of nitrate to induce nitrate reductase in higher plants has been widely accepted [l]. Nitrate alone, however, is not always sufficient to induce the enzyme in higher plants. Light [2] and C02 [3] are also necessary, suggesting that photosynthesis furnishes some essential component of the induction process triggered by nitrate. We have previously shown [4] that induction of nitrate reductase may be obtained by spraying suitable amounts of plant hormones on the leaves of tobacco plants in the dark. It has been shown also that adding certain respiratory substrates to nitrate in etiolated barley leaves allows induction of the enzyme in the dark [5]. Nitrate, therefore, promotes induction of nitrate reductase only under conditions which permit formation of nitrite. The reduction of nitrate requires photosynthesis of a carbon compound which yields, upon oxidation, the electrons necessary for the reduction. We have suggested [6] that glycolate is the photosynthetic compound required for nitrate reduction because the enzyme system which oxidizes glycolate and the enzyme-reducing nitrate are located in microbodies. Glycolate dehydrogenase activity has been detected in plants actively reducing nitrate [7]. Nitrate reduction takes place in the dark when the leaves are supplemented with suitable respiratory substrates [5] such as glucose, phosphoglyceric acid or glycolate ; this exogeneous supply substitutes photosynthesis as a source of energy-yielding substrates for the reduction of nitrate and the generation of nitrite. Since reduction of nitrate to nitrite takes place in both cases (photosynthesis or supplementation of

Hydrogen solubility in jojoba oil

Abstract: The solubility of hydrogen in jojoba oil has been determined at temperatures of 50–250 C and pressures between 100–800 psig. The system behaves according to Henry’s law with a heat of solution of 1240 cal/g mole and entropy of solution of 2.9 cal/K g mole. The partial volume of hydrogen varies between 24.6–62.9 ml/g mole in the temperature range considered.

Notes and correspondence: Comment on “tetroon studies in the crowsnest pass area”

Abstract: of proceedings. These will be judged on their merits and presented in whole or in part as the paging of the JOURNAL permits.

Molecular Motion in Liquids from Low Frequency Depolarized Light Scattering

Abstract: In this work we present theories for low frequency depolarized light scattering from liquids. Expressions for the various line shapes are given which depend on the geometry of the experiments and on temperature. We show how details of the rotational, translational and vibrational molecular motion can be extracted from these experiments.

A remark on degeneration of a compact Riemann surface of genus 2

Abstract: A compact Riemann surface of genus 2, whose period matrix (π ij ) is arbitrary, is degenerated, thus removing a restriction on the degeneration in a previous paper by the author.

The Influence of Heat Upon Intellectual Test Performance and Cardiac Activity of Three Groups in the Negev Desert

Abstract: This study was conducted to determine if exposure to heat at 45 deg;C, influences mental test performance and heart rates of different ethnic groups living in the same area of a semi-desert zone. Forty-eight adolescent highschool boys of Israeli nationality (but whose fathers were of Bedouin, Moroccan or Eastern European background) were paid for their participation. Each of the boys was individually tested under control or heat conditions by an experimenter from the same ethnic background on a Raven 38 and WISC Coding B task. Mental test performances were unaffected by either one or two hours of heat although heart rates increased. More basic than heat was ethnic membership and test scores corresponded more to assumed experience with tests than to any other factor. Heart rate patterns were also different between the 3 groups suggesting fundamental physiological divergence. RESUME Cette etude a pour but de determiner l'effet que peut avoir une temperature de 45 °C sur les resultats de tests mesurant le quotient intellectuel et sur le rythme cardiaque d'individus appartenant a des ethnies differentes mais habitant tous la měme region d'une zone semi-desertique. Quarante-huit adolescents de nationalite israelienne (mais dont les peres etaient d'origine bedouine, marocaine ou d'Europe orientale) furent engages et payes pour participer a cette experience. Chacun des garcons fut examine individuellement dans des conditions de temperature normale puis a la temperature de 45 °C, par un technicien issu du měme groupe ethnique qui utilisait les tests Raven 38 et WISC Coding B. Les resultats des tests ne furent en aucun cas modifies par un sejour d'une ou deux heures dans une temperature ambiante de 45 °C; le rythme cardiaque, en revanche, augmenta sensiblement. Il semble, par ailleurs, que l'appartenance a un groupe ethnique donne ait constitue un facteur plus important que les changements de temperature et que ce soit entre les scores reels et une familiarite possible avec des tests de ce type que la correspondance la plus marquee ait ete observee. Les courbes de rythme cardiaque des trois groupes differaient sensiblement, ce qui semble indiquer une difference physiologique fondamentale entre ces groupes.

An analysis of diffraction formulae

Abstract: In this paper various diffraction formulae deseribing elastie scattering of spinless uncharged particles are analysed. Expressions for thel-dependence of theS-matrix elements of boundary condition models are derived and compared with directS-matrix models. Some incompatibility between the two different approaches, which are supposed to describe the same phenomenon, are found. In the derivation of Kirchhoff’s diffraction formula there exists an incompatibility of the boundary conditions. Namely, for its derivation one should know both the values of the wave function and the normal component of the gradient of the wave function on the absorbing sphere. The solutions to bo both boundary problems are separately presented. The reflection from the absorbing sphere is treated and new formulae are derived. The differential and total cross-sections of the described models are analysed.