The detection of geothermal areas from Skylab thermal data

Skylab-4 X-5 thermal data of the geysers area was analyzed to determine the feasibility of using midday Skylab images to detect geothermal areas. The hottest ground areas indicated on the Skylab image corresponded to south-facing barren or sparsely vegetated slopes. A geothermal area approximately 15 by 30 m coincided with one of the hottest areas indicated by Skylab. This area could not be unambiguously distinguished from the other areas which are believed to be hotter than their surroundings as a result of their topography, and micrometeorological conditions. A simple modification of a previous thermal model was performed and the predicted temperatures for the hottest slopes using representative values was in general agreement with the observed data. It is concluded that data from a single midday Skylab pass cannot be used to locate geothermal areas

EFFECT OF MICROORGANISMS ON FREE AMINO ACID AND FREE D-AMINO ACID CONTENTS OF VARIOUS DAIRY PRODUCTS

Free amino acid and free D-amino acid contents of milk samples with different microorganism numbers and composition of dairy products produced from them were examined. Total microorganism number of milk samples examined varied from 1.25x106 to 2.95x106. It was established that concentration of both free D-amino acids and free L-amino acids increased with an increase in microorganism number. However, increase in D-amino acid contents was higher considering its proportion. There was a particularly significant growth in the microorganism number range from 1.5x106 to 2.9x106. Based on analysis of curds and cheese samples produced using different technologies we have come to the conclusion that for fresh dairy products and for those matured over a short time there was a close relation between total microorganism number and free D-amino acid and free L-amino acid contents. At the same time it was found that the ratio of the enantiomers was not affected by the total microorganism number. For dairy products, however, where amino acid production capability of the microbial cultures considerably exceeds, production of microorganisms originally present in the milk raw material, free amino acid contents of the milk product (both D- and L-enantiomers) seem to be independent of the composition of milk raw material

SEPARIRANJE I ODREĐIVANJE ENANTIOMERA AMINOKISELINA KOJE SADRŽE SUMPOR POMOĆU TEKUĆE KROMATOGRAFIJE VISOKE PERFORMANCE

Performic acid oxidation of cysteine and methionine resulting in the formation of cysteic acid and methionine sulphon has been applied in order to avoid the loss of these two sulphur containing amino acids during the acidic hydrolysis of proteins that is necessary prior to amino acid analysis. The aim of the research was assigned by the increasing demand for the determination of the amount of amino acid enantiomers: the applicability of performic acid oxidation was evaluated from this point of view. Racemization of L-cysteine and L-methionine was found not significant during oxidation with performic acid, therefore this process can be applied before hydrolysis during quantification of cysteine and methionine enantiomers. Additionally, the quantification of cysteic acid and methionine sulphon enantiomers was accomplished in the form of their diastereoisomer derivatives via the development of a reversed phase of high performance liquid chromatography method.Proces oksidacije performičnom kiselinom cisteina i metionina, što rezultira stvaranjem cisteične kiseline i sulfona metionina primijenjen je kako bi se izbjegao gubitak te dvije aminokiseline koje sadrže sumpor, za vrijeme acidične hidrolize bjelančevina, potrebne prije analize aminokiselina. Cilj istraživanja potakli su sve veći zahtjevi za određivanjem količina enantiomera aminokiselina: primjenjivost oksidacije performične kiseline ocijenjena je s tog gledišta. Racemizacija L-cisteina i L-metionina nije se pokazala značajnom za vrijeme oksidacije s performičnom kiselinom pa se, stoga, taj proces može primijeniti prije hidrolize tijekom kvantifikacije cisteinskih i metioninskih enantiomera. Osim toga, kvantifikacija cisteične kiseline i enantiomera metionskog sulfona izvedena je u obliku derivata njihovih dijastereosomera putem razvoja obrnute faze metode tekuće kromatografije visoke performance

A new method for the quantitative determination of protein of bacterial origin on the basis of D-aspartic acid and D-glutamic acid content

In the past years several methods have been developed for the determination of the proportion of the nitrogen-containing substances of microbial origin passed from the rumen into the abomasum or the small intestine. Recently, on examining the D-amino acid content of foodstuffs, particularly milk and milk products, it has been observed that, in addition to D-Ala, D- glutamic acid (D-Glu) and D-aspartic acid (D-Asp) can also be detected in similar quantities, primarily in products which have links with bacterial activity. This gave rise to the idea of examining the diaminopimelic acid (DAPA), D-Glu and D-Asp content of bacteria extracted from the rumen of cattle and that of chyme from the same cattle, in order to determine the type of relation existing among these three components, and to establish whether D-Asp and D-Glu can be used in the estimation of protein of bacterial origin. On determination of the DAPA, D-Asp and D-Glu content by means of amino acid analyser and high performance liquid chromatography of duodenal chyme from five growing bulls and of ruminal bacteria from the same bulls, the following values were established. For chyme (and, in brackets, for ruminal bacteria) r value calculated by means of linear regression was 0.78 (0.76) between DAPA and D-Asp, and 0.70 (0.81) between DAPA and D-Glu. The r values between the crude protein content of ruminal bacteria and the markers examined were found to be the following: DAPA, 0.74; D-Asp, 0.73; D- Glu, 0.61. In the model experiment performed for the re-obtaining of values for protein of bacterial origin the theoretical values were determined on the basis of D-Asp and D-Glu and values approximately 10% higher than the theoretical value on the basis of DAPA. It is therefore recommended that in addition to DAPA these other two amino acids be included among the bacterial protein markers

Spintronics: Fundamentals and applications

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes from the published versio

Ciliate-generated advective seawater transport supplies chemoautotrophic ectosymbionts

Variations of [O2] and [H2S] in seawater surrounding laboratory reared sessile ciliates with ectosymbiotic chemoautotrophic bacteria were studied at high spatial and temporal resolutions using amperometric microsensors. We show how suspension feeding by the colonial Zoothamnium niveum and the solitary Vorticella sp. in the chemocline (O2/H2S-interface) of near-natural and artificial H2S-releasing substrates generates the physico-chemical microenvironment for the ectobiotic bacteria. Continuous recordings revealed a steep increase of [O2] and decrease of [H2S] in the proximal region of Z. niveum colonies during rapid stalk contraction. Hydrogen sulphide concentrations 2.5 mm above the substrate (upper end of the fully extended colony) increased when the contracted colony extended, followed by a decrease after the colony attained the fully upright position. Multiple contractions without complete extension successively transported sulphidic seawater upwards. The solitary Vorticella sp. maintained high ambient [O2] and low [H2S] 350 μm above the H2S-releasing membrane by generating a vertical flow field that drew seawater from above toward the ciliate. Oxygen concentration at the proximal part of Vorticella sp. did not increase during contraction, whereas during slow extension deoxygenated seawater was transported upwards and rapidly mixed with the surrounding oxygenated seawater when the ciliate started to beat its cilia. In both species rapid stalk contraction and subsequent slow extension enhanced the mixing of oxygenated and deoxygenated, H2S-containing seawater; the feeding currents (toroidal vortices) drew the surrounding seawater within reach of the zooid’s external surface at high speed. It is suggested that this advective fluid transport supplies the ectobiotic bacteria with O2 and H2S simultaneously. The high fluid velocity may cause a decrease in cell boundary layer thickness, thereby enhancing rates of nutrient uptake by the ectobiotic bacteria