A Study of the Malpighian Tubules of the Pill Millipede, Glomeris marginata (Villers)

1974 ◽  
Vol 60 (1) ◽  
pp. 41-51
Author(s):  
PATRICIA ANNE FARQUHARSON
Keyword(s):  
Size Distribution ◽  
Fluid Transport ◽  
Molecular Size ◽  
Malpighian Tubules ◽  
Inverse Relation ◽  
Fluid Production ◽  
Molecular Size Distribution ◽  
Molecular Sieving ◽  
Tubule Fluid ◽  
Tubule Wall

1. Tubule fluid:medium ratios (TF/M) have been measured for inulin, glucose, LMWD and HMWD. These TF/M ratios were surprisingly high. 2. The tubule appears to act as a molecular filter; that is to say, molecules move through the tubule wall in inverse relation to their size. This is best illustrated using polyvinyl pyrrolidone as a tracer. The molecular size distribution of PVP fractions present in tubule fluid differs markedly from the molecular size distribution of PVP in the bathing Ringer. 3. No correlation can be made between the inulin and glucose TF/M and the rate of fluid production. However, the inverse relationship between TF/M and rate of fluid production for dextrans indicates a molecular sieving effect. 4. The significance of these results is discussed with reference to models of fluid transport.

A Study of the Malpighian Tubules of the Pill Millipede, Glomeris marginata (Villers)

1974 ◽  
Vol 60 (1) ◽  
pp. 29-39
Author(s):  
PATRICIA ANNE FARQUHARSON
Keyword(s):  
Osmotic Pressure ◽  
Electrical Potential ◽  
Malpighian Tubules ◽  
Potassium Ions ◽  
Electrical Potential Difference ◽  
Ion Concentrations ◽  
Fluid Production ◽  
Tubule Fluid ◽  
Sodium And Potassium ◽  
Tubule Wall

1. Isolated Malpighian tubules of Glomeris produce fluid which is identical to the bathing media with respect to ion concentrations and osmotic pressure. 2. The tubules secrete normally in a potassium-free Ringer, but they cease to function in a sodium-free Ringer. 3. The rate of fluid production is dependent on the availability of sodium ions, but it is also inhibited by higher concentrations (25 mM/l of potassium ions. 4. Throughout a wide variation in concentrations of sodium and potassium ions in the bathing Ringer, the concentrations of these ions in the tubule fluid are the same as their concentrations in the Ringer. 5. Fluid production by the tubules of Glomeris is inhibited by ouabain at a concentration of 5x10-6M/l or greater. 6. The rate of fluid production varies inversely with the osmotic pressure, and the secreted fluid remains approximately isosmotic to the bathing media. 7. No electrical potential difference could be recorded across the tubule wall.

Determination of the Size Distribution of Dissolved Organics in Effluents

1973 ◽  
Vol 8 (1) ◽  
pp. 1-15 ◽  
Author(s):  
L.A. Addie ◽  
K.L. Murphy ◽  
J.L. Robertson
Keyword(s):  
Size Distribution ◽  
Biological Treatment ◽  
Oxygen Demand ◽  
Molecular Size ◽  
Monitoring Systems ◽  
Clean Surface ◽  
Sephadex Column ◽  
Dissolved Organics ◽  
Molecular Size Distribution

Abstract The importance of removing the small amounts of residual organics is increasing as the sources of clean surface water decrease. Knowledge of the nature of these soluble residual organics will be needed in order to assess the type of treatment required for their removal. Residual organics in three different biological treatment plants were analyzed and compared. An attempt was made to characterize these organics by a molecular size distribution on a Sephadex column monitored by differential ultraviolet and refractive index detectors. The organic carbon and chemical oxygen demand of the fractions collected from the column was also determined. An investigation of some of the problems inherent in the monitoring systems was conducted.

Molecular Size Distribution of Lignin in Wood

Nature ◽  
1967 ◽  
Vol 214 (5086) ◽  
pp. 410-411 ◽  
Author(s):  
W. BROWN ◽  
S. I. FALKEHAG ◽  
E. B. COWLING
Keyword(s):  
Size Distribution ◽  
Molecular Size ◽  
Molecular Size Distribution

scholarly journals Molecular-size-distribution-dependent aggregation of humic substances by Na(I), Ag(I), Ca(II), and Eu(III)

2013 ◽  
Vol 434 ◽  
pp. 9-15 ◽  
Author(s):  
Shuji Tamamura ◽  
Ryutaro Ohashi ◽  
Seiya Nagao ◽  
Masayoshi Yamamoto ◽  
Motohiro Mizuno
Keyword(s):  
Humic Substances ◽  
Size Distribution ◽  
Molecular Size ◽  
Molecular Size Distribution

Multidetectors for Analysis of the Composition of Copolymers as a Function of Molecular Size Distribution by Steric Exclusion Chromatography

1973 ◽  
Vol 46 (2) ◽  
pp. 449-463 ◽  
Author(s):  
D. J. Harmon ◽  
V. L. Folt
Keyword(s):  
Liquid Chromatography ◽  
Size Distribution ◽  
Oil Content ◽  
Molecular Size ◽  
The Other ◽  
Additional Information ◽  
Steric Exclusion ◽  
Gel Permeation ◽  
Exclusion Chromatography ◽  
Molecular Size Distribution

Abstract Analysis of molecular size distribution of polymers by steric exclusion liquid chromatography (GPC) is well known. Problems exist, however. These problems involve copolymers and polymer blends. The objectives of the research were to develop methods of analyzing comonomer distribution in copolymers, to study the breakdown of one polymer independent of another in a polymer blend, and to obtain any additional information as might be available. The separations were performed on a Waters Model 200 Gel Permeation Chromatograph. Detectors employed were a Waters R-4 differential refractometer, a Wilks Miran-1 infrared analyzer, and a Beckman Model 144 UV photometer. Examples are given of analysis of average styrene, styrene distribution, and oil content of oil extended SBR. The data is compared with that obtained by other methods. In general the agreement is good. The ability to examine one polymer of a blend independent of the other is also demonstrated. Since elastomers are frequently used as blends, this becomes very important to such studies as milling and extrusion behavior.

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