Some local factors affecting iridic lipid infiltration in hypercholesteremic rabbits

1959 ◽  
Vol 197 (4) ◽  
pp. 842-846 ◽  
Author(s):  
Meyer Friedman ◽  
Sanford O. Byers
Keyword(s):  
Cottonseed Oil ◽  
Aortic Tissue ◽  
Factors Affecting ◽  
Experimental Animals ◽  
Local Factors ◽  
Laboratory Conditions ◽  
Intermittent Exposure ◽  
Intense Light

The influence of various factors affecting the deposition of lipid and cholesterol in the iris of rabbits fed cholesterol and cottonseed oil was studied. It was observéd that this deposition could be increased by the intraocular implantation of either normal aortic tissue or polyethylene discs. In an additional study, it was found that intermittent exposure of the eyes of cholesterol-fed rabbits to intense light also provoked an earlier and more intense iris deposition of lipid and cholesterol than was observed in the eyes of similarly fed rabbits kept either in absolute darkness or under ordinary laboratory conditions. It was postulated that the factor responsible for the greater iridic deposition observed in all these experimental animals was the iridic vasodilatation effected by these experimental measures.

scholarly journals The nylon bag technique in the determination of ruminal feed protein degradation

1983 ◽  
Vol 55 (1) ◽  
pp. 1-78 ◽  
Author(s):  
Jouko Setälä
Keyword(s):  
Particulate Matter ◽  
Pore Size ◽  
Control Sample ◽  
Sample Treatment ◽  
Sample Weight ◽  
Factors Affecting ◽  
Experimental Animals ◽  
Incubation Periods ◽  
Feed Protein

The investigation included experiments in which factors affecting the reliability of the nylon bag method were studied. The possibility of applying the feed protein degradabilities to practical feeding conditions was also examined. In the experiments concerning reliability, such factors as bag porosity, sample weight, sample treatment, washing procedure, diets, and differences between animals and incubation days were studied. The feed protein degradabilities were also determined by using as incubation periods the ruminal retention times for particulate matter of different feeds, evaluated as a function of DM intake/100 kg liveweight in different diets. A nylon bag, with a pore size of 40 µm and internal dimensions of 6 X 12 cm was selected for the degradability determinations. The sample weight used in incubations was 57 —60  mg DM/cm2. In the determination of feed protein degradability, when sheep are used as experimental animals, it is recommended that for routine determinations only one animal be used, analyzing the contents of two bags for each incubation period during two successive days. A control sample of which degradability is determined in advance in many sheep, should be used in all incubations in order to control the digestive processes in the rumen of the experimental sheep. The actual degradabilities analyzed by the bag method are applicable in practise, if they are determined using animals at similar feeding levels and on diets similar to those prevailing under the conditions in which the degradabilities are going to be used.

Mechanism of Rubber Cracking

1946 ◽  
Vol 19 (2) ◽  
pp. 406-416 ◽  
Author(s):  
E. F. Powell ◽  
V. E. Gough
Keyword(s):  
Laboratory Tests ◽  
Surface Film ◽  
Factors Affecting ◽  
Laboratory Conditions ◽  
Service Conditions ◽  
Exposure Conditions

Abstract Rubber and rubberlike polymers, in common with other materials which deteriorate on exposure to oxidizing or similar agents, eventually crack under normal atmospheric service conditions. The present paper confines itself to the factors affecting the type and appearance of the cracking which eventually occurs when a surface film of a rubber object (particularly when stressed) hardens and deteriorates in strength from any cause whatsoever. The importance of an understanding of the effects of exposure conditions on the character of the cracking produced cannot be too highly emphasized. This is so even if interest is confined solely to simple tests on new protective paints on an acceptance basis rather than research into surface deterioration. It is probable that many protective agencies have been accepted or rejected for extensive production tests because the initial laboratory tests have either not been representative of service or have been inadequate in scope. This still remains a major problem. The theory presented here has gradually taken shape over a period of some ten years and appears to describe adequately the general findings on the whole gamut of cracking, viz., fine check cracking and isolated deep cracks produced under service and laboratory conditions, the latter covering flexing, roof exposure, ozone and similar tests.

Share of rushes in water uptake in shallow lakes in eastern Poland

2020 ◽  
Vol 56 ◽  
pp. 5
Author(s):  
Joanna Sender ◽  
Monika Różańska-Boczula ◽  
Antoni Grzywna
Keyword(s):  
Water Uptake ◽  
Shallow Lakes ◽  
Lake District ◽  
Emergent Macrophytes ◽  
Factors Affecting ◽  
Laboratory Conditions ◽  
Number Of Leaves ◽  
Field Works ◽  
Respective Species

The intensity of transpiration depends on many environmental factors including light, temperature, wind, and air humidity. By eliminating the variation of these factors under laboratory conditions, an attempt was made to indicate the intensity of this process among different species of helophytes and are there any factors limiting this process. We performed a field study of some shallow lakes to answer the question: what is the role of emergent macrophytes in evapotranspiration in lakes with different trophy and surface. Field works were carried out in the shallow littoral at the peak of the growing season. Under laboratory conditions five species were analysing in respect of water uptake. Under laboratory conditions, the width, length and number of leaves as well as the mass and diameter of the stems of respective species had the most significant effect on the uptake of water by helophytes. The length of the plant was a characteristic with the least significant impact on water uptake. The presence of inflorescence was highly negatively correlated with the amount of water taken up by the plants. This phenomenon may slow down the process of water uptake by plants. Among the analyzed factors affecting the uptake of water in the shallow lakes of the Łęczna-Włodawa Lake District, the most important effect was the area of rushes, their density and lake trophic type. In contrast, the type of lake supply, surface of the lake and the variety of helophytes proved to be irrelevant to the amount of water uptake. Helophytes play a significant role in the uptake of water. The share of Typha rushes significantly increases transpiration.

scholarly journals Factors affecting the inactivation of micro-organisms by intense light pulses

2005 ◽  
Vol 99 (3) ◽  
pp. 460-470 ◽  
Author(s):  
V.M. Gomez-Lopez ◽  
F. Devlieghere ◽  
V. Bonduelle ◽  
J. Debevere
Keyword(s):  
Factors Affecting ◽  
Light Pulses ◽  
Intense Light ◽  
Micro Organisms ◽  
Intense Light Pulses

scholarly journals Local factors affecting the testate amoeba community (Protozoa: Arcellinida; Euglyphida) in a neotropical floodplain

2015 ◽  
Vol 73 (AoP) ◽  
Author(s):  
Rodrigo L. Arrieira ◽  
Geziele M. Alves ◽  
Leilane T. F. Schwind ◽  
Fabio A. Lansac-Tôha
Keyword(s):  
Testate Amoeba ◽  
Factors Affecting ◽  
Local Factors ◽  
Neotropical Floodplain

Factors affecting the acquisition of resistance against Schistosoma mansoni in the mouse. I. Demonstration of resistance to reinfection using a model system that involves perfusion of mice within three weeks of challenge

1978 ◽  
Vol 52 (3) ◽  
pp. 173-186 ◽  
Author(s):  
M. Doenhoff ◽  
Q. Bickle ◽  
E. Long ◽  
J. Bain ◽  
A. McGregor
Keyword(s):  
Schistosoma Mansoni ◽  
Primary Infection ◽  
Model System ◽  
Challenge Infection ◽  
Factors Affecting ◽  
Experimental Animals ◽  
Challenge Control ◽  
Excretion Rates ◽  
Homologous Challenge

ABSTRACTThe degree of resistance acquired by Schistosoma mansoni-infected mice against homologous challenge has been determined by perfusion of the animals within three weeks of the challenge, at which time the challenge-derived organisms were morphologically distinguishable from the primary infection which induced the resistance. The method has been compared with assays based on determination of the number of organisms migrating through the lung, and with perfusions at a later time when the challenge has matured. The results obtained with the three week perfusion method, showing that resistance was acquired by eight weeks after a primary infection, were confirmed by the longer survival of, and reduced egg excretion rates and tissue egg burdens in the experimental animals relative to respective challenge control animals. However, some discrepancy in challenge-derived worm numbers was found between animals perfused three weeks after challenge and those autopsied at later times. The possible reasons for this difference are discussed. The degree of resistance that was acquired was to some extent dependent on the size of the challenge infection.

scholarly journals Comparative Study of Aortic Wall Stress According to Geometric Parameters in Abdominal Aortic Aneurysms

2021 ◽  
Vol 11 (7) ◽  
pp. 3195
Author(s):  
Ji-Hun You ◽  
Chung Won Lee ◽  
Up Huh ◽  
Chi-Seung Lee ◽  
Dongman Ryu
Keyword(s):  
Aortic Rupture ◽  
Wall Stress ◽  
Aortic Aneurysms ◽  
Aortic Tissue ◽  
Factors Affecting ◽  
Abdominal Aortic ◽  
Geometric Factors ◽  
Measurement Results ◽  
Simulation Scenario ◽  
Peak Wall Stress

In abdominal aortic aneurysm (AAA), the rupture of the aortic tissue is directly related to wall stress. Thus, the investigation of maximum wall stress is a necessary procedure to predict the aortic rupture in AAA. In this study, computational simulations were performed to investigate the correlation between peak wall stress (PWS) and AAA geometry. The Holzapfel model and various orientations of the collagen fibers and thicknesses of the layers of the aorta were employed in the simulation. The material constants used in the Holzapfel model were estimated from the examination and analysis of the biaxial tensile test results of the normal abdominal aorta and AAA. The aneurysm diameter, height, neck angle, and iliac angle were selected as geometric factors affecting the AAA rupture. In addition, a simulation scenario was conceived and created based on the measurement results using the computed tomography data of patients with AAA. Accordingly, the correlation between the PWS and AAA geometry was estimated.

Occurrence and simulation of nitrification in two contrasting sugarcane soils from the Australian wet tropics

Soil Research ◽  
2006 ◽  
Vol 44 (1) ◽  
pp. 1 ◽  
Author(s):  
E. A. Meier ◽  
P. J. Thorburn ◽  
M. E. Probert
Keyword(s):  
Incubation Period ◽  
Tropical Soils ◽  
Ammonium Nitrogen ◽  
Mineral N ◽  
Factors Affecting ◽  
Laboratory Conditions ◽  
Complex Processes ◽  
Nitrate N ◽  
Subtropical Soils ◽  
Wet Tropics

The concentration of ammonium-nitrogen (NH4+-N) frequently exceeds that of nitrate-N (NO3−-N) in Australian wet tropical sugarcane soils. The amount of mineral N in soil is the net result of complex processes in the field, so the objective of this experiment was to investigate nitrification and ammonification in these soils under laboratory conditions. Aerobic and saturated incubations were performed for 1 week on 2 wet tropical soils. Net NO3−-N increased significantly in both soils during both types of incubation. A second series of aerobic incubations of these soils treated with NH4+-N and inoculated with subtropical nitrifying soils was conducted for 48 days. Nitrification in the wet tropical soils was not significantly affected by inoculation, and virtually all added N was nitrified during the incubation period. Mineral N behaviour of the 48-day incubations was captured with the APSIM-SoilN model. As nitrification proceeded under laboratory conditions and was able to be captured by the model, it was concluded that nitrification processes in the wet tropical soils studied were not different from those in the subtropical soils. Processes that remove NO3− from the soil, such as leaching and denitrification, may therefore be important factors affecting the proportions of NH4+-N and NO3−-N measured under field conditions.

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