Damping studies of aging in Al-Cu

Precipitation in an Al-3 pct Cu age-hardening alloy has been monitored at 130°C by ultrasonic pulse-echo measurements of attenuation and sonic velocity at 15 to 75 mHz and resonance bar damping and dynamic modulus measurements at 80 kHz. The use of two internal friction measurement techniques allows separation of the total damping loss into its component parts. Damping and modulus defect remain constant with time up to 100 hr, whereupon they begin to increase and reach a maximum at 250 hr. The observed time dependence is associated with scattering losses by precipitate particles and with increasing dislocation damping as dislocations become increasingly mobile during the depletion of their solute atmospheres by growing solute-rich precipitates.     

Present prognosis in neonatal meningitis

A retrospective study of neonatal meningitis for a period of 6 years (1970 to 1975) is described. It was found that though the survival rate had increased since the introduction of the aminoglycosides, it was at the expense of major neurological sequelae in the survivors. It is suggested that breast feeding of all infants in the first few days of life will reduce the incidence of neonatatl meningitis. It is recommended that pooled human breast milk should not be heat-sterilized as this destroys anti-Escherichia coli immunoglobulin A.     

Solar device for the candle industry

A solar device has been developed for manufacturing candles from paraffin wax, utilizing solar energy. The design, operation and performance of the device have been described. It is concluded that the device can be used for saving fuel, minimizing the loss of wax due to the vaporization and labour.     

Viscosity-molecular weight concentration relationships beyond the critical region in polymer solutions and melts

A multivariate regression analysis of viscosity-molecular weight-concentration data is presented which is superior to the methods currently used. Four sets of data from the literature are analysed to show the efficacy of the method.     

The effect of zinc and phytic acid on the incorporation of 1-14C-acetate into aflatoxin by resting mycelia of Aspergillus parasiticus.

The effect of zinc and phytic acid on [1-14C]-acetate incorporation into aflatoxins by resting mycelium was studied. When different levels of ZnSO4 were used to study its effect on the incorporation of [1-14C]-acetate into aflatoxins, it was found that the specific radioactivity incorporation into aflatoxins was maximum at the level of 10 mM-ZnSO4. At this concentration the change in the specific radioactivities of aflatoxins B1 + B2 and aflatoxins G1 + G2 were +74.61% and +29.66%, respectively. On the other hand, phytic acid had an inhibitory effect on the incorporation of [1-14C]-acetate. These observations have been correlated in order to find out why soyabean is unable to produce aflatoxins by Aspergillus parasiticus.     

Hydromagnetic stability of helical flows permeated by a magnetic field with a radial component

In this paper, we have studied the linear stability of the nondissipative helical flow of an incompressible perfectly conducting fluid between two concentric cylinders permeated by a non-zero radial magnetic field. It is found that a rigidly rotating column of a perfectly conducting fluid permeated by a magnetic field [($\text{A/r}$), ($\text{C/r}$), $\text{B}{}_0$], where $\text{A, C, B}{}_0$ are constants, is stable for all infinitesimal disturbances.     

Schnellmethode zur Bestimmung des ?lanteils in Lecithin

Zusammenfassung Eine Schnellmethode zur routinemäßigen Bestimmung des Ölanteils in Handelsleeithin und ähnlichen Phospholipidproben wurde ausgearbeitet. Sie beruht auf der Beobachtung, dam 1 g Phospholipid an 45 g mit Wasser desaktiviertem Kieselgel unter den Versuchsbedingungen vollständig adsorbiert werden.Die Lecithinprobe wird in ätherischer Lösung durch eine mit desaktiviertem Kieselgel gefüllte Säule filtriert und mit etwas Äther nacheluiert. Das gesamte Äther-Eluat wird i. Vak. eingedampft und der Rückstand gewogen. Dieser Rückstand entspricht dem Ölanteil, der aus Mono-, Di- und Triglyceriden, freien Fettsäuren, Sterinen und deren Derivaten besteht. Eine Bestimmung dauert etwa 20 min.

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A rapid method for determination of oil in lecithins

Summary A rapid method for routine determination of oil in commercial lecithins and similar phospholipid samples has been worked out. This based on the observation that under the described experimental conditions 1 g of phospholipids is completely adsorbed on 45 g silica gel which has previously been disactivated by the addition of 15% water.The lecithin sample is filtered in ethereal solution through a column filled with disactivated silica gel which is subsequently washed with a little ether. The combined ether eluates are evaporated to drynessin vacuo and the residue weighed. This residue is the oil part of the sample and is constituted of mono-, di-, and triglycerides, free fatty acids, sterols and their derivatives. The duration for one such determination is about 20 min.

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Vorgetragen anläßlich des 11. ISF-Kongresses in Göteborg, Juni 1972.     

Effect of Variation in Matrix Constitution on the Work Hardening Behavior of a Peak Age Hardened SiC Reinforced Aluminum Based Metal-Matrix Composite

An understanding of the work hardening behavior of particulate reinforced metal -matrix composites is crucial in optimizing the parameters for deformation processing of these materials. In the case of particulate reinforced composites with an age hardenable aluminum alloy matrix, the microstructure and mechanical properties can be altered by a suitable aging treatment as well as by changing the content of alloying elements in the matrix. In this study MMCs with different levels of Cu in the matrix were prepared and aged to peak hardness. A modified continuum model was then used to relate the work hardening behavior of the composites to microstructural parameters. The model is shown to be accurate for all the composite materials investigated in the present study.     

11Beta-hydroxysteroid dehydrogenase type 2 in human pregnancy and reduced expression in intrauterine growth restriction

The evolutionary theory of aging predicts that the equilibrium gene frequency for deleterious mutations should increase with age at onset of mutation action because of weaker (postponed) selection against later-acting mutations. According to this mutation accumulation hypothesis, one would expect the genetic variability for survival (additive genetic variance) to increase with age. The ratio of additive genetic variance to the observed phenotypic variance (the heritability of longevity) can be estimated most reliably as the doubled slope of the regression line for offspring life span on paternal age at death. Thus, if longevity is indeed determined by late-acting deleterious mutations, one would expect this slope to become steeper at higher paternal ages. To test this prediction of evolutionary theory of aging, we computerized and analyzed the most reliable and accurate genealogical data on longevity in European royal and noble families. Offspring longevity for each sex (8409 records for males and 3741 records for females) was considered as a dependent variable in the multiple regression model and as a function of three independent predictors: paternal age at death (for estimation of heritability of life span), paternal age at reproduction (control for parental age effects), and cohort life expectancy (control for cohort and secular trends and fluctuations). We found that the regression slope for offspring longevity as a function of paternal longevity increases with paternal longevity, as predicted by the evolutionary theory of aging and by the mutation accumulation hypothesis in particular.     

Theoretical evaluation of viscosity of binary molten electrolytes

Significant structure theory (SST) of Eyring has been employed to calculate theoretically the viscosity of binary molten electrolytes on the basis of rigid sphere model. For KClNaCl and KClKBr systems the agreement between theoretical and experimental values is found to be satisfactory.