The Instability of Hevea Latex

1941 ◽  
Vol 14 (1) ◽  
pp. 133-136
Author(s):  
Paul Stamberger
Keyword(s):  
Specific Conductivity ◽  
Chemical Compounds ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Specific Substance ◽  
Bacterial Action ◽  
Sodium Pentachlorophenate ◽  
Bacterial Decomposition ◽  
Colloidal State ◽  
Serum Components

Abstract In a study made on plantations in Malaya, it was found that the cause of instability is not the same for both fresh and preserved latex. The autocoagulation of fresh latex, as it will be shown, is not caused by the acid formed by bacterial action on the serum components (autoacidification). Coagulation takes place, in fact, when decomposition of the serum components is prevented by the addition of strong antiseptics. These experiments, carried out in 1938 and 1939 in Malaya, support Whitby's view that autocoagulation is not due to autoacidification, but is probably caused by enzyme action on the protein or other serum components of the latex. The behavior of preserved latex is entirely different. Coagulation on storage was found to be due to acid formation and neutralization of the preserving agent applied. Decomposition of serum components was found in cases when coagulation did not take place, which would naturally influence the further behavior of latex. The action of the preserving agents is not a simple one. Inhibiting bacterial growth and preventing decomposition are not enough to keep the latex in the liquid, colloidal state. In addition to antiseptics, chemical compounds which act specifically as coagulation preventatives must be present. Rhodes recommends 0.1 per cent ammonia in addition to sodium pentachlorophenate. This small quantity of ammonia, as it was found, is the specific substance, probably an enzyme poison, which prevents coagulation. A number of additional substances in combination with sodium pentachlorophenate were tried, and it was found that adjusting the hydrogen ion concentration on the alkali side was not sufficient to prevent coagulation, although bacterial decomposition was inhibited. Observing the changes in the specific conductivity of latex during storage was the most satisfactory method found to measure the value of preserving agents or combinations of preserving agents. An increase in the specific conductivity of latex was found after a few days' storage, provided that the preserving agent did not inhibit decomposition of the serum components. From this increase in conductivity on storage, it could be predicted whether or not the preserving agent tested would give satisfactory results, or whether or not the concentration of the preserving agent was sufficiently high.

Studies on the Nutrition of Blow-Fly Larvae

1931 ◽  
Vol 8 (2) ◽  
pp. 109-123 ◽  
Author(s):  
R. P. HOBSON
Keyword(s):  
Proteolytic Enzymes ◽  
Anterior Segment ◽  
Posterior Segment ◽  
Ion Concentration ◽  
Gut Contents ◽  
Middle Segment ◽  
Hydrogen Ion Concentration ◽  
Alkaline Reaction ◽  
Bacterial Action ◽  
Hind Gut

1. The mid-gut in Lucilia larvae can be divided into three distinct regions (termed anterior, middle and posterior segments). 2. Histologically the anterior and posterior segments are similar. In a feeding larva the cells are highly vacuolated and contain fat; in a starved larva the cells are deeply staining and non-vacuolated. In the middle segment the cells are always deeply staining and free from vacuoles and fat, whatever the state of nutrition. 3. The hydrogen-ion concentration varies along the gut and with the nature of the food. With liquefied meat as food, the pH is 7.5-8.0 in the crop, 7.5 in the anterior segment, 3.0-3.5 in the middle segment, 7.5-8.3 in the posterior segment, and 8.0-8.5 in the hind-gut. With fresh gelatine (pH 7.0) as food, the values are the same except in the crop and anterior segment, for which the figures are respectively pH 7.0 and 6.5. 4. It has been suggested that the acidity in the middle segment may be due to an acid secretion, the most likely component being phosphoric acid. The alkaline reaction in other parts of the gut is probably caused by ammonia, which is present in the gut-contents and excreta. 5. Tryptase, peptidase and lipase are present in the mid-gut, the enzymes being concentrated in the anterior and posterior segments. The proteolytic enzymes persist in the excreta and some extra-intestinal digestion, therefore, can occur without the aid of micro-organisms. Carbohydrate-splitting enzymes are absent except for a feeble secretion of amylase in the salivary gland. 6. By combining the evidence from various sources, I have attempted to obtain a complete picture of the process of digestion, which I suggest is as follows: The food is stored unchanged in the crop and, passing into the mid-gut, is rapidly forced into the middle segment. Some absorption of water and simple products of bacterial action occurs along the anterior segment, the concentration of the food being completed in the middle segment where the acidity prevents digestion. The food, by now of a pasty constituency, passes into the posterior segment, dissolves in the alkaline fluid and is digested and absorbed. The digestive enzymes are secreted in the anterior and posterior segments, but digestion does not progress far in the anterior segment owing to the rapid passage of the food.

scholarly journals A comparative study of winter wheat varieties with especial reference to winter-killing

1922 ◽  
Vol 12 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Robert Newton
Keyword(s):  
Winter Wheat ◽  
Dry Matter ◽  
Freezing Point ◽  
Specific Conductivity ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Wheat Varieties ◽  
Hydrogen Ion Concentration ◽  
Winter Wheat Varieties ◽  
Hardened Condition

1. A number of varieties of winter wheat, known to vary considerably in degree of winter hardiness, were compared in the hardened condition with reference to the physical constants of the cell sap, and the content of dry matter, nitrogen, sugars and starch.2. No constant relation was found between depression of the freezing point, specific conductivity, or hydrogen-ion concentration of the cell sap and relative frost hardiness.3. Sugars accounted for 34 to 38 per cent, of the total osmotic pressure of the sap.

scholarly journals STUDIES ON THE REGULATION OF OSMOTIC PRESSURE

1921 ◽  
Vol 3 (6) ◽  
pp. 801-806 ◽  
Author(s):  
Walter W. Palmer ◽  
Dana W. Atchley ◽  
Robert F. Loeb
Keyword(s):  
Sodium Chloride ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Specific Conductivity ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Degree Of Ionization ◽  
Hydrogen Ion Concentration ◽  
Egg Albumin ◽  
Cent Sodium

1. In pure gelatin solutions the conductivity of the solution increases with increasing concentrations, regardless of the hydrogen ion concentration. The actual value of the specific conductivity is greater at that reaction where the degree of ionization is greater. 2. The addition of gelatin in increasing concentrations to a 0.6 per cent sodium chloride solution affects the conductivity of that solution in two ways: (a) At pH 3.3, (where gelatin is highly ionized) the conductivity increases with each added increment of gelatin. (b) At pH 5.1 and 7.4 (where gelatin is less highly ionized) the conductivity decreases with each added increment of gelatin. A similar study is being made of crystalline egg albumin.

The Kinetics of the Coagulation of Latex of Hevea Brasiliensis and the Separation of the Hydratant Acid

1938 ◽  
Vol 11 (1) ◽  
pp. 60-74 ◽  
Author(s):  
N. H. van Harpen
Keyword(s):  
Hevea Brasiliensis ◽  
Physical System ◽  
Point Of View ◽  
Solid Particles ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Technical Problems ◽  
Semi Solid ◽  
The Right ◽  
Serum Components

Abstract In the present work, an attempt is made to study the process of coagulation of Hevea brasiliensis latex, so familiar to every rubber expert, from a general colloid-chemical point of view, and to ascertain the physical conditions under which the kenetic phenomena take place. Hevea Brasiliensis Latex as a Physical System In “The Electrometric Determination of the Hydrogen Ion Concentration in the Latex of Hevea brasiliensis and Its Applicability to Technical Problems” the true character of Hevea brasiliensis latex as a physical system and the phenomena which take place during coagulation of this system are discussed in the light of investigations and observations of various rubber experts. Latex is a dispersion composed of polydispersed rubber hydrocarbon, serum components, and water. The rubber component consists of microscopically visible solid or semi-solid particles, in Brownian movement, and judged by the degree of affinity of rubber for water these particles are unquestionably lyophobic. Since the serum components are in a colloidal state, they are present as sols or emulsions, and they impart to the latex its lyophilic properties. It is possible, however, to choose the conditions of coagulation so that, for a given concentration of dispersed substances and at a given temperature, the dispersion will be predominantly lyophobic or lyophilic. This dual standard leads to the conclusion that Hevea brasiliensis latex is a pseudo-lyophilic dispersion. In saying this, it should be noted that, although the dispersion has several lyophilic properties, it is nevertheless essentially a lyophobic system, the properties of which become manifest under the right conditions.

INVESTIGATION OF BEE BREAD AND DEVELOPMENT OF ITS DOSAGE FORMS

2014 ◽  
Vol 21 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Ilze Barene ◽  
Irena Daberte ◽  
Sanita Siksna
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Potato Starch ◽  
Microscopic Analysis ◽  
Stability Study ◽  
Ion Concentration ◽  
Wet Granulation ◽  
Hydrogen Ion Concentration ◽  
Bee Bread ◽  
Layer Chromatography

The aim of the study. The objective of this study was to investigate microscopic, physical and chemical properties of bee bread collected in three regions of Latvia in order to compare the quality and to investigate the possibility of producing granules containing bee bread. Material and methods. Microscopic analysis of bee bread samples was performed. Plant herbaria, special literature and internet sources were used for identification of pollen. Thin layer chromatography was used for identification of carotenoids and flavonoids. Granules were prepared by wet granulation method. Lactose, calcium lactate, calcium carbonate, potato starch and purified water were used as excipients. Appearance, loss on drying, pH of aqueous solution and content of carotenes were estimated. Results. Microscopic analysis showed mostly native pollen identified as willow pollen. Beta-carotene identified and 2 carotenoids found by thin layer chromatography. Two zones of flavonoids found on chromatograms at day light and 6 zones at ultra violet light. The comparison of bee bread samples of 3 regions of Latvia showed insignificant differences in appearance and consistency, hydrogen ion concentration 3.93–4.23, loss on drying 7.72–11.07 %; content of carotenes calculated to bcarotene 6.77–9.35 mg%. Stability study of bee bread samples showed greater changes after storage at 40ºC temperature. All compositions of granules showed appropriate appearance and flowability. Quality of granules: loss on drying 5.48–13.5%, content of carotenes calculated to b-carotene 5.77–6.75 mg%. Conclusions. Pollen of willow can be considered as an indicator of the origin of bee bread in Latvia. Bee bread samples of three regions of Latvia have insignificant differences in physical, chemical parameters.

Hydro-geochemical properties with respect to landuse in the southernmost river of Kerala

2018 ◽  
Vol 6 (1) ◽  
Author(s):  
Badusha M. ◽  
Santhosh S
Keyword(s):  
Organic Carbon ◽  
Drainage Basin ◽  
Anthropogenic Activities ◽  
Oxygen Demand ◽  
Ion Concentration ◽  
Total Hardness ◽  
Hydrogen Ion Concentration ◽  
Geochemical Properties ◽  
Quality Of Water

The hydro geochemical features of Neyyar River for a period of one year from May 2015 to April 2016 were analyzed. Six sampling sites were fixed considering physiography and present landuse pattern of the river basin. The residents in the drainage basin are primarily responsible for framing a better landuse and thereby maintain a good water and sediment regime. Geospatial pattern of the present landuse of the study area indicated that the sustainability of this river ecosystem is in danger due to unscientific landuse practices, which is reflected in the river quality as well. The parameters such as hydrogen ion concentration, electrical conductivity, chloride, Biological Oxygen Demand, total hardness and sulphate of river water and Organic Carbon of river bed sediments were analyzed in this study. The overall analysis shows that the highland areas are characterized by better quality of water together with low organic carbon, which is mainly due to better landuse and minimal reclamation. The midland and lowland areas are characterized by poor quality of water with high organic carbon, which is due to high anthropogenic activities and maximum pollutants associated with the region together with the alteration in landuse from a traditional eco-friendly pattern to a severely polluted current pattern.

EFFECTS OF SOIL ACIDITY ON RHIZOBIA NUMBERS, NODULATION AND NITROGEN FIXATION BY ALFALFA AND RED CLOVER

1977 ◽  
Vol 57 (2) ◽  
pp. 197-203 ◽  
Author(s):  
W. A. RICE ◽  
D. C. PENNEY ◽  
M. NYBORG
Keyword(s):  
Nitrogen Fixation ◽  
Soil Ph ◽  
Soil Acidity ◽  
Field Experiments ◽  
Rhizobium Meliloti ◽  
Acid Soils ◽  
Red Clover ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Greenhouse Experiments

The effects of soil acidity on nitrogen fixation by alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were investigated in field experiments at 28 locations, and in greenhouse experiments using soils from these locations. The pH of the soils (limed and unlimed) varied from 4.5 to 7.2. Rhizobia populations in the soil, nodulation, and relative forage yields (yield without N/yield with N) were measured in both the field and greenhouse experiments. Rhizobium meliloti numbers, nodulation scores, and relative yields of alfalfa decreased sharply as the pH of the soils decreased below 6.0. For soils with pH 6.0 or greater, there was very little effect of pH on any of the above factors for alfalfa. Soil pH in the range studied had no effect on nodulation scores and relative yields of red clover. However, R. trifolii numbers were reduced when the pH of the soil was less than 4.9. These results demonstrate that hydrogen ion concentration is an important factor limiting alfalfa growth on acid soils of Alberta and northeastern British Columbia, but it is less important for red clover. This supports the continued use of measurements of soil pH, as well as plant-available Al and Mn for predicting crop response to lime.

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