Activity Ratios for Farm Machinery Operations Analysis

1974 ◽  
Vol 17 (2) ◽  
pp. 0225-0227 ◽  
Author(s):  
Kenneth Von Bargen ◽  
M. B. Cunney
Keyword(s):  
Farm Machinery ◽  
Activity Ratios

Evaluation of 99mTc-Label led Vitamin K4 as an Agent for Testicular Imaging

1991 ◽  
Vol 30 (01) ◽  
pp. 35-39 ◽  
Author(s):  
H. S. Durak ◽  
M. Kitapgi ◽  
B. E. Caner ◽  
R. Senekowitsch ◽  
M. T. Ercan
Keyword(s):  
Soft Tissue ◽  
Room Temperature ◽  
Normal Subjects ◽  
Left Testis ◽  
Wide Range ◽  
Activity Ratios ◽  
The Right ◽  
Radioactivity Levels

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 ±9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 ±6.3% as determined by TCA precipitation. Blood clearance of 99mTc-l<4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 ±0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection.99mTc-l<4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.

FARM MACHINERY ECONOMICS

2013 ◽  
Author(s):  
W. Edwards
Keyword(s):  
Farm Machinery

A PC model for selecting multicropping farm machinery systems

1996 ◽  
Vol 14 (1) ◽  
pp. 43-59 ◽  
Author(s):  
Massimo Lazzari ◽  
Fabrizio Mazzetto
Keyword(s):  
Farm Machinery

scholarly journals Regulation of acetyl-CoA carboxylase in rat mammary gland. Effects of starvation and of insulin and prolactin deficiency on the fraction of the enzyme in the active form in vivo

1982 ◽  
Vol 204 (1) ◽  
pp. 273-280 ◽  
Author(s):  
Elizabeth M. McNeillie ◽  
Victor A. Zammit
Keyword(s):  
Mammary Gland ◽  
Enzyme Activities ◽  
Enzyme Concentration ◽  
Acetyl Coa Carboxylase ◽  
Initial Activity ◽  
Acetyl Coa ◽  
Activity Ratios ◽  
Rat Mammary Gland ◽  
Rate Limiting

The ‘initial’ (I), endogenous phosphatase-activated (A) and citrate-activated (C) activities of acetyl-CoA carboxylase were measured in mammary-gland extracts of pregnant and lactating rats. There was a 10-fold increase in the A and C enzyme activities in the transition from early to peak lactation [cf. data of Mackall & Lane (1977) Biochem. J.162, 635–642], but there was no significant increase in the ratio of the initial activity to the A and C activities of the enzyme. Starvation (24h) or short-term (3h) streptozotocin-induced diabetes both resulted in a 40% decrease in I/A and I/C activity ratios. In starvation this was accompanied by a decrease in the absolute values of the A and C activities such that the initial activity in mammary glands of starved animals was 45% that in glands from fed animals. Insulin treatment of starved or diabetic animals 60min before killing increased the I activity without affecting the A or C enzyme activities. Removal of the pups for 24h from animals in peak lactation (weaning) resulted in a marked but similar decrease in all three activities such that, although the initial activity was only 10% of that in suckled animals, the I/A and I/C activity ratios remained high and unaltered. Inhibition of prolactin secretion by injection of 2-bromo-α-ergocryptine gave qualitatively similar results to those during weaning. Simultaneous administration of ovine prolactin completely prevented the effects of bromoergocryptine. It is suggested that the initial activity of acetyl-CoA carboxylase in rat mammary gland is regulated by at least two parallel mechanisms: (i) an acute regulation of the proportion of the enzyme in the active state and (ii) a longer-term modulation of enzyme concentration in the gland. Insulin appeared to mediate its acute effects through mechanism (i), whereas prolactin had longer-term effects on enzyme concentration in the gland. A comparison of initial enzyme activities (I) obtained in the present study with rates of lipogenesis measured in vivo [Agius & Williamson (1980) Biochem. J.192, 361–364; Munday & Williamson (1981) Biochem. J.196, 831–837] gave good agreement between the two sets of data for all conditions studied except for 24h-starved and streptozotocin-diabetic animals. It is suggested that acetyl-CoA carboxylase activity is rate-limiting for lipogenesis in the mammary gland in normal, fed, suckled or weaned animals but that in starved and short-term diabetic animals changes in the activity of the enzyme by covalent modification alone may not be sufficient to maintain the enzyme in its rate-limiting role.

FIXATION AND RELEASE OF POTASSIUM IN RELATION TO THE MINERALOGY OF THE CLAY FRACTION OF SOME SELECTED SOIL HORIZON SAMPLES

1971 ◽  
Vol 51 (3) ◽  
pp. 449-459 ◽  
Author(s):  
A. J. MacLEAN ◽  
J. E. BRYDON
Keyword(s):  
Clay Fraction ◽  
High Capacity ◽  
Soil Horizon ◽  
Exchangeable K ◽  
High Release ◽  
Soil Clays ◽  
Activity Ratios ◽  
Plant Removal ◽  
Satisfactory Relationship ◽  
Intermediate Amount

Soil clays of 11 horizon samples of Canadian soils gave activity ratios (AReK) of 0.0003 to 0.0040, exchangeable K values of 0.18 to 1.74 meq/100 g, nonexchangeable K values of 1.54 to 6.65 meq/100 g upon leaching with 12 liters of 0.1 N BaCl2 and of 0.45 to 4.03 meq as measured by plant removal, and degrees of K-fixation of 29 to 100% of added K against extraction with 1 N NH4OAc. The amounts of exchangeable K were correlated with the activity ratios and with the amounts of non-exchangeable K removed by plants. Of the fixed K, 46 to 86% was recovered by leaching with the 0.1 N BaCl2 and 18 to 64% by cropping. Some of the clays gave a satisfactory relationship between their K behaviour and mineralogy. Two of them (Ae, Humo-Ferric Podzol), consisting of mixtures of vermiculite and montmorillonite, released native K slowly and had a high capacity to fix added K. Another corresponding sample, from the C horizon and consisting of well-ordered 2 M1 muscovite, also released native K slowly but gave the lowest degree of K-fixation. A predominantly montmorillonite clay with some mica layers (Gray Luvisol) gave a high release of native K and fixed an intermediate amount of added K. The K–mineralogy relationship in the remaining samples was less apparent, and varied with the complexity of interstratification.

scholarly journals Fluid Chemistry of Mid-Ocean Ridge Hydrothermal Vents: A Comparison between Numerical Modeling and Vent Geochemical Data

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-20 ◽  
Author(s):  
Samuel Pierre ◽  
Alexander P. Gysi ◽  
Thomas Monecke
Keyword(s):  
Numerical Modeling ◽  
Geochemical Data ◽  
Fluid Composition ◽  
Secondary Mineral ◽  
Ambient Seawater ◽  
Mineral Solution ◽  
Mid Ocean Ridge ◽  
Activity Ratios ◽  
Proton Activity ◽  
Ocean Ridge

Seawater-basalt interaction taking place at mid-ocean ridges was studied using numerical modeling to determine the compositional evolution of hydrothermal fluids and associated alteration mineralogy forming within newly emplaced crustal material. Geochemical modeling was carried out in a closed seawater-basalt system at discrete temperature intervals between 2 and 400°C at 500 bars, varying fluid/rock ratios, and secondary mineral assemblages representative of basalt alteration in natural systems. In addition to temperature, the fluid/rock ratio has a fundamental control on the resulting system chemistry. At rock-buffered conditions (low fluid/rock ratios), the mineral-solution equilibrium was characterized by high cation to proton activity ratios foraCa2+/(aH+)2andaNa+/aH+and very low dissolved Mg concentrations due to the precipitation of smectites and chlorite. A complex secondary mineral alteration assemblage dominated by Ca- and Na-bearing minerals including zeolites, calcite, epidote, prehnite, clinozoisite, and albite was predicted to form. The resulting fluid composition was alkaline and reduced relative to ambient seawater, with Eh values ranging between −0.2 and −0.6 V. In contrast, seawater-buffered conditions (high fluid/rock ratios) resulted in lower cation to proton activity ratios foraCa2+/(aH+)2andaNa+/aH+and higher dissolved Mg concentrations comparable to the value of this element in ambient seawater. A more simple mineral assemblage was predicted to form at these conditions with the predominance of Al-Si- and Mg-bearing minerals including kaolinite, quartz, and talc in addition to large amounts of anhydrite. The resulting fluid composition was mildly acidic and oxidized relative to seawater with Eh values ranging between −0.2 and 0 V. These modeling results were compared to a compilation of submarine hydrothermal vent fluid compositions from mid-ocean ridge settings and analogous basalt-dominated environments. The agreement obtained between the simulations and the compiled fluid data indicates that mid-ocean ridge hydrothermal processes can be closely reproduced by mineral-solution equilibria for a broad range of temperatures and fluid/rock ratios.

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