Thin Ones Research Articles

Effect of Particle Size on Potassium Sorption by Potassium-Depleted Phlogopite

AbstractSorption of K from mixed KCl and CaCl2 solutions by K-depleted, Ca-saturated phlogopite was studied to determine the effect of particle size. The experiments were done at room temperature with 25 mg of K-depleted phlogopite samples in 50 ml solutions which were 0·002 N with respect to KCl and 0·02 N with respect to CaCl2.Sorption of K increased sharply with increase in particle size. The 54–75 μm fraction sorbed nearly all, whereas the 0·2–2 μm fraction sorbed less than half, of its depleted K. The 5–20 μm fraction sorbed an intermediate amount. This relationship is explained by the same hypothesis which accounts for the increase of K release with increase in particle size. That is, bending of unit mica layers due to peripheral expansion is greater in large and thick particles than in small and thin ones. This increased bending induces the greater K release from large particles. Similarly, bending due to peripheral collapse of hydrated layers is greater in large particles than in small ones. Thus, more energy is needed to initiate layer collapse and restrict further K uptake in the large particles which results in their greater K sorption capacity.These results imply that in natural conditions, as in soils, the coarse vermiculite and weathered mica fractions may be more effective in sorbing K from solution than their fine counterparts.

Clinical Disorders of Fluid and Electrolyte Metabolism,

This book is the second edition of a new standard text and reference dealing with body water and solutes. The approach is comprehensive. As a subject, fluid and electrolyte metabolism can be defined either broadly or narrowly and the books about it are thick or thin accordingly. Thin ones (there are several in print) usually begin with a chapter on fundamentals of compartments, pools, and spaces and of acid-base chemistry, go on to classify abnormalities of fluid homeostasis, and then outline treatment for each category. Maxwell and Kleeman's book is one of the other, thick kind. Just as the world can be seen in a grain of sand, the entire field of medicine can be approached from the fluid and electrolyte point of view. In this book, chapters are devoted to systematic consideration of specific disease entities: acute and chronic renal failure, cardiovascular disease, endocrine disorders and a variety of

Estimation of ionic conductivity of CuI through tarnishing studies of copper in iodine atmosphere

The conductivity values of isolated CuI crystal has been reported by a large number of investigators. But the conductivity be-haviour of a growing CuI film on copper has not been explored yet. An attempt has been made in this investigation to provide ionic conductivity values of growing CuI films from the kinetics studies of the film growth process. The conductivity value has been found to be proportional to the square of the partial pressure of iodine in the thinner film range while it is approximately proportional to the square root of the partial pressure in the thicker range. Estimation has been based on the fundamental parabolic equation of Wagner relating the rate constant and conductivity. An analysis of the experimental results indicate that the conductivity value of the growing CuI is of higher magnitude for thicker films than that for the thinner ones.

Three morphological types of motor nerve terminals in the rat diaphragm, and their possible innervation of different muscle fiber types.

With methylene blue stain, 3 types of motor terminals were distinguished in the rat diaphragm. Type A terminals possess long slender branches and numerous minute terminal boutons, type C ones fewer thick branches and few large terminal boutons, and type B ones possess intermediate characteristics. In three animals, type A constitutes 20.5% (s.d. 2.5), B 20.0% (s.d. 3.0), and C 59.5% (s.d. 3.5). Type A terminals are often but not always larger than type C, type B terminals overlapping with both size ranges. Type A terminals tend to innervate thick muscle fibers and type C thin ones, type B innervating muscle fibers of intermediate width. The frequencies of occurrence of types A, B, and C terminals closely parallel the frequencies of so-called “white”, “intermediate”, and ”red” muscle fibers, respectively, as determined with a fat stain.

Branching Colony Pore Structure in Anodic Alumina Films

A LARGE cellular structure may be present underneath thick porous anodized films grown on aluminium in chromic acid and an alkaline borate electrolyte1. We termed these “secondary” cells because their population was much smaller than the number of pores in the anodic film as counted from electron micrographs of either surface replicas of thick films or transmission through very thin ones. It appears that these cells are not related to the pretreatment or subgrain structure of the base metal. Their presence has now been confirmed by electron-optical examination of cross-sections of anodic films grown on super-pure aluminium (99.999%) in a 10% chromic acid solution at 30 V, 40° C. The method for the preparation and taking replicas of film sections was similar to that described by Wood and O'Sullivan2. An A.E.I. ‘E.M.6.G.’ electron microscope was used for the examination of the replicas.

Submicroscopical aspects of chick embryo parathyroid glands

Parathyroid glands from chick embryos ranging from 8 days of incubation up to hatching time were fixed in half-strength Karnovsky's fixative, postfixed in osmium tetroxide, stained in bulk with 2% uranyl acctate, dehydrated, and embedded in Araldite. Thick sections were stained with toluidine blue and thin ones with lead citrate. At all ages, the gland was formed by cords of cells which appeared darkly stained by the toluidine blue, and electron opaque with the electron microscope. Few clear cells were intermingled with the main cell type. The cytoplasm of dark cells contained at all ages, free ribosomes, mitochondria with a dense matrix, a well developed Golgi complex, profiles of rough-surfaced endoplasmic reticulum, coated vesicles, lipid droplets, and lysosomes. After day 13 of incubation, small vesicles containing a material of low density (prosecretory granules) appeared in the Golgi zone. The presence of these cytoplasmic elements tends to support the idea that the glands are already active during the embryonic period. The role of clear cells has not been established. Islands of apparently active ultimobranchial “C” cells were found with some frequency within the parathyroid glands.

Separation of thick and thin myofilaments

Methods have been developed for separating the thin myofilaments from the thick ones in two molluscan muscles, the opaque adductor of the oyster, and the crossstriated adductor of Pecten. The thick filaments of these muscles have also been obtained with only a small contamination by thin ones. The media used in all procedures were designed to keep the filaments intact. Either differential centrifugation or zone velocity sedimentation on sucrose or glycerol density-gradients may be used; the latter method promises to be more generally useful. The sedimentation coefficients of these natural myofilaments (as measured under the conditions of the experiments) are: $ ̃ 34 s and $ ̃ 50 s for the thin filaments from the oyster muscle; $ ̃ 33 s for the thin filaments and $ ̃ 300 s for the thick filaments from the Pecten muscle. The S-value for the thick filaments from the oyster muscle is too large to be measured. Both myosin and paramyosin were found in the thick filaments of the oyster muscle and the Pecten muscle. Attempts to separate the thick and thin filaments of glycerol-extracted rabbit psoas muscle are also described; the problems involved are discussed.

Dimensional effects occuring under investigation of S-type voltampere characteristics in Ge

It is analysed the effect of sample dimensions upon the form of S-type voltampere characteristics (VAC) which occur at a low-temperature impact ionization of gallium impurities in Ge. It is found that VAC of thick samples have jumps and hysteretic regions which are absent in thin ones. A temperature gradient arising due to Ettingshausen effect has an influence on VAC's stability in thick samples. Experimental results are in agreement with theory.

Relationship of Body Composition to Energy Intake and Energetic Efficiency

In heifers of dairy breeds and ranging in age from 1 day to 14 months, weights of body protein and fat and the amount of body energy increased linearly with increasing empty-body weight. That the variation in the respective relationships is small is indicated by the r2 of 0.997, 0.961, and 0.985. The rate of change in body energy per kilogram of empty-body weight was 2.55 Meal. Although the data examined represent animals with a variety of nutritional histories, much further study is needed to determine the degree to which relationships between the body components and body weight will resist nutritional alteration.In dairy cows 28 months to 15 years of age, relationships between body components and body weight were quite variable, reflecting the mobility of body fat, water, and protein. Although these relationships have no predictive value, they suggest general trends such as the overall rate of change of 4.38 Meal, of energy per kilogram of empty-body weight.Composition and energy value of the body tissue gain or loss by cattle are variable. Energy equivalence values (Meal per kg) derived from various studies with cows range from 4.8 to 9.4 for body gain and from 6.3 to 7.9 for body loss. It appears possible that body tissue gain or loss could range from as much as 100% of water to about 90% of fat.Increasing degrees of body fatness in ruminants are associated with decreasing intakes of feed. The mechanism by which fatness influences appetite is not known. However, it is possible that the accumulation of fat in the abdominal cavity, in a manner similar to that of the developing gravid uterus, might restrict gastrointestinal capacity to curtail appetite, especially when high-forage diets are ingested. Present information suggests that the intake of high-concentrate diets is regulated by other or additional means. It has been proposed that body fat depots of fat animals may release substances that depress appetite or that the adipose tissue of thin cows may utilize some unknown products of digestion at a greater rate than does the adipose tissue of fat cows to increase intake by thin cows.In fat ruminants, digestibility of energy may be depressed at a lower intake of feed than it is in thin ones, as the level of intake increases. Whether the energy requirement for maintenance is influenced by body fatness in cattle is unsettled; in sheep, the maintenance requirement does not appear to be different for fat and thin animals. for body gain, the net utilization of the metabolizable energy ingested above maintenance appears unaffected by the degree of fatness in ruminants of the same sex. Additional study is needed to determine the effect of body fatness on the energy requirement of maintenance in cattle, especially in the lactating cow.

Ultrastructure of the neurogenic heart of Limulus polyphemus.

The ultrastructure of Limulus cardiac muscle was examined. The hearts were fixed in situ by perfusion with isotonic glutaraldehyde solution while in relaxed, contracted, or stretched states. The sarcomeres are relatively long, varying in length from about 2.5 to 6.6 μ. The average A-band length is 2.46 μ. M lines are absent, and H zones are poorly distinguished. Thick and thin filament diameters average about 200 A and 50 A, respectively; each thick filament is surrounded by 8–12 thin ones. Superficial invaginations of the sarcolemma occur, making contact with the Z lines of the outermost myofibrils. There is an extensive sarcoplasmic reticulum and transverse (T) tubules. Some T tubules run longitudinally and some open into deep sarcolemmal invaginations which extend into the fiber interior. The T tubules swell markedly in hypertonic solution. Single neurons and small bundles of neurons are observed in close apposition with myocardial cells. Intercalated disks are found in Limulus heart at regions of contact between contiguous myocardial cells lying end to end; semitight or gap junctions are essentially absent. Prominent differences in sarcomere lengths sometimes occur across the disk, thus indicating that the disks demarcate cells functionally. Hence, in addition to direct motoneuron activation, there may be some transfer of excitation across the intercalated disks in accord with our previous finding that propagating, overshooting action potentials can be induced in this heart.

Production and distribution of dry matter in trees of Coffea arabica L. in Kenya as affected by seasonal climatic differences and the presence of fruits

SUMMARYStandard growth analysis procedures were used to study the production and distribution of dry matter in 3 1/2 to 5‐year‐old coffee trees through their first and into their second commercial fruiting year. The trees were growing in the field and were treated according to normal commercial practice. Up to fifteen fruiting and deblossomed trees were harvested on each of seven occasions, at intervals of 63–90 days. The dry weights of four aerial fractions, five root fractions and all fallen, picked and pruned material were recorded.The net assimilation rate (E) of deblossomed trees was as large as that recorded in East Africa for coffee seedlings (0·13 g dm‐2wk‐1). Fruiting trees increased in dry weight faster than deblossomed trees, even when their leaf area was 30% smaller. Their E was up to 0·19 g dm‐2wk‐1when expressed on a leaf area basis and up to 0·16 g dm‐2wk‐1even when the total green fruit surface area was included in the calculation.In the hot, dry season, January–February 1968, all parts of the trees increased in dry weight relatively slowly, except the thin roots (< 3 mm diameter) which, in this season, took about 10% of the dry weight increment. The trees had been pruned in December and E of deblossomed trees was only 0·09 g dm‐2wk‐1.Flushes of shoot growth occurred at the beginning of the Long Rains 1967 and 1968 (February–March). During the 1967 shoot growth flush, 61% of the dry weight increment was used in the production of new, large leaves with a mean specific leaf area of over 140 cm2g‐1. The thin roots took about 10 % of the increment, but the thicker roots increased in weight very slowly. The branches and trunk extended rapidly, but their radial growth was relatively slow.Following the shoot growth flushes, the leaf area ratio of the trees was large (0·38 dm2g‐1in 1967) and during the Long Rains (April–June 1967, 1968), when conditions were favourable for photosynthesis (E 0·13 g dm‐2wk‐1), all parts increased in dry weight relatively rapidly, although in 1968 the thin roots took as little as 3 % of the total increment. Leaf area ratio decreased during the Long Rains owing to a large decrease in specific leaf area (in 1967: 118 to 95 cm2g‐1).Pruning was carried out in June and new leaf production during the cool, dry season, July to mid‐September, was very slow. Consequently, the total dry weight increase of the trees during this season was relatively small, although the E of deblossomed trees was 0·13 g dm‐2wk‐1. The leaves, which took 33 % of the increment, decreased further in specific leaf area (to 83 cm2g‐1) and most root fractions increased in dry weight rapidly, the thin ones taking 17 % of the increment.Light fruiting in 1967 did not affect the seasonal periodicity in growth described. Both light and heavy fruiting tended, eventually, to lessen the dry weight increase of leaves and thin roots proportionately more than that of the trunk and thick roots. In 1968 fruiting trees retained over 8000 fruits per tree, which took over 70 % of the dry weight increment during the 1968 Long Rains, and became 36 % of the trees' dry weight. Some rootlets on these trees decreased in weight.Aspects of the productivity, growth periodicity and fruiting of coffee are discussed, and some management implications are noted.

Interpretation of crayfish hepatopancreatic function based on fine structural analysis of epithelial cell lines and muscle network.

The ultrastructure of R-, F-, and B-cells and of the myoepithelial network in crayfish hepatopancreas tubules was studied as a basis for the functional interpretation of hepatopancreatic digestive activity: 1. R-cells absorb luminal nutrients, mainly via contact digestion and molecular transport, and they store and metabolize glycogen and lipids. To this extent, R-cells combine the functions of vertebrate intestinal absorptive and hepatic parenchymal cells. 2. F-cells synthesize digestive enzymes and sequester them in a supranuclear vacuole which enlarges by pinocytic intake of luminal nutrients and fluids. 3. F-cell to B-cell transformation results from continued engorgement of the F-cell's supranuclear vacuole until only the nuclear region and a pinocytically activeapical complex remain identifiable. 4. B-cell secretion involves pinching off of the apical complex followed by extrusion of the enzyme-rich vacuolar contents. 5. The tubule's myoepithelial network consists of circular fibers, each containing a single myofibril, which branch to form longitudinal fibers. Sarcomeres are long (10–12 μ) and each thick myofilament is surrounded by 11–13 thin ones. This arrangement permits coordinated, tonic contractions of tubule segments which transport nutrients “in” and enzymes “out”. 6. Neurosecretory control of tubular function is suggested by the presence of vesicle-containing, extratubular cell processes which contact the circular muscle fibers.

Silver Staining of Insect Central Nervous Systems by the Bodian Protargol Method

Improved fixation of ganglia of the central nervous system of Periplaneta americana and Schistocerca gregaria for silver staining by Power's (1943) modification of the Bodian protargol method is given by alcoholic Bouin aged for at least 40 days at 60° C. During impregnation of sections, increased copper and decreased pH give paler staining, more selective for nerve fibres. Prolonging impregnation from 24 to 48 hours weakens the stain and decreases selectivity. The intensity of the stain depends chiefly upon the amount of unreduced (developable) silver combined with the tissues; selectivity is determined mainly by the number and distribution of the reduced silver particles (‘nuclei’). In development, increased sodium sulphite gives more differentiation, increased hydroquinone gives less. Optimum developer composition depends upon impregnation, and thick sections need more differentiation than thinner ones. Within limits, change in one of the factors that control staining can be balanced by changes in others, but by suitable adjustment of the conditions the result can be varied from almost total staining of nerve fibres, for general neuroanatomy, to highly selective staining for tracing individual fibres.

Wound contraction in rabbits and the effectiveness of skin grafts in preventing it

FULL thickness cutaneous wounds in mammals heal by contraction (Billingham and Reynolds, 1952; Billingham and Medawar, 1955) with varying degrees of success depending upon their anatomical location, the tissues involved and the species of animal. It is well recognised that contraction may be prevented by covering the wound with a skin graft, thicker grafts being more effective than thinner ones (Brown and McDowell, 1958 ; Fomon, 196o). Padgett (1942) observed that whereas a thin graft on the neck may contract by 60 per cent, a thick graft contracts by only IO to 30 per cent, while with full thickness grafts, contraction is negligible. Billingham and Russel (1956) went further and stated that coverage of a fresh as well as a granulating and actively contracting full thickness cutaneous wound with a full thickness skin graft completely inhibits contraction, whereas thin grafts are almost ineffective in retarding contraction. In fact, we have been unable to trace any controlled study on the role of skin grafting in preventing wound contraction. In view of the paucity of work on this aspect of wound healing, a detailed study has been undertaken (I) to elucidate the effectiveness of skin grafts in preventing wound contraction and (2) the difference in the effectiveness of skin grafts of varying thickness, and (3) to estimate the degree to which the contraction of a wound is retarded by coverage with grafts should they be effective in doing so.

ENERGY REQUIREMENTS FOR WINTERING MATURE PREGNANT BEEF COWS

Experiments to determine the energy requirement of cows maintained on shortgrass range during the grazing season were conducted in three successive winters. Mature pregnant cows fed a high level (17,000 to 19,000 kcal per day) of digestible energy (DE) gained 33 kg during a mild winter, maintained their weight during a second winter of frequent high winds combined with low temperatures, and lost 16 kg in a third winter. On a medium level of DE intake (about 80% of high level) the cows gained 14 kg in a mild winter but lost 8 kg and 32 kg in a second and third winter. Cows fed a low level (about 60% of the high level) of DE lost 12 kg weight, several died, and some very thin ones were unable to stand even in the mild winter. During the second winter, all of the cows in the low-level group, several in the medium-level group, and a few in the high-level group were removed from the experiment because of their thin condition. Frequent combination of low temperatures and high winds appear to have contributed to higher energy requirements in the second and third winters than in the first winter.Level of nutrition of the dams did not affect average birth weights of calves. Calves from cows fed on the high levels of DE gained more to weaning than calves from cows on the low level of DE. The cows on the low level of DE in winter gained more weight in summer than those on the medium or high level of DE. The extra feed required to restore body weight of cows on the low level of DE apparently reduced the amount available for milk production and thus the weight gain of the calves.The NRC level of 18,000 kcal DE per day appeared to be suitable for wintering mature pregnant cows that are kept on the shortgrass plains during the grazing season.

The resistivity of fine platinum wires

We have measured the resistivity of pure platinum wires ranging in diameter from 16 mil to 0.3 mil in the temperature range 1.2 to 4.2°K, and observed size-dependent deviations from Matthiessen’s rule. The temperature dependent portion of the resistivity is dominated in this temperature range by a term of the formAT 2, whereA increases from about 12×10−12 Ω cm/°K2 for the thickest wires to 18×10−12 Ω cm/°K2 for the thinnest ones. There is an additional resistivity contribution which appears to increase more rapidly thanT 5, and which also evidences some increase with decreasing wire diameter. The observed deviations from Matthiessen’s rule display temperature and size variations consistent with the theory ofBlatt andSatz, and the magnitude of the deviations can be accounted for by this theory taking into account only that portion of the electrical resistivity produced by electron-phonon scattering. Thus the data are consistent with arguments suggesting that interband electron-electron scattering does not lead to size-dependent deviations from Matthiessen’s rule.

Radiometric studies of mercury loss from fungicidal paints. 1. Loss of phenyl mercuric acetate

AbstractExposure tests have been made on paint films prepared from an emulsion paint containing phenyl mercuric acetate (PMA) labelled with 203Hg. Loss of mercury from the films has been followed radiometrically.Films exposed indoors in a confined space (no air circulation) showed little, if any, mercury loss for up to 8 months. Films exposed in the open laboratory lost from 20 to more than 60% of mercury after 250 days. This agrees qualitatively with the results of other workers on similar paints. At 50°, films lost mercury at rates about 10 times greater than those at ambient temperature.Films exposed out‐of‐doors lost the majority of their mercury after a few days of rain. Pre‐treatment of films, e.g. by u.v. radiation, had no effect on their subsequent outdoor behaviour. Even well‐dried films lost mercury at the same rate as newly applied films.Films with a low PMA content (0·02% Hg) lost mercury at a higher percentage rate than films with a high one (0·2% Hg). Thick films (0·002 in.) lost mercury at a lower rate than thin ones (0·001 in.). A mercury‐free top coat also reduced loss rate. All loss rates decreased with increasing time. These trends applied to all the exposure conditions studied.Mercury loss appears to be due to both volatilisation and dissolution of PMA and not to decomposition. The results indicate a non‐homogeneous distribution of PMA throughout the paint film, and a diffusion‐controlled process.

The structure of the central nervous system of a pulmonate molluse (Cryptomphallus aspersa). I. Ultrastructure of the connective epineural sheath.

The connective epineural sheath of the abdominal mass ganglia of the land snail Cryptomphallus aspersa was studied by light and electron microscopy. In this sheath several cellular types were found: fibroblasts, macrophage cells, a special type rich in mitochondria; elongated cells which proved to be muscle cells of paramyosin type and glial cells with dense bodies in close contact with neurosecretory axons. Special attention was paid to the filaments of the muscle cells. Thin and thick ones were found, the last with cross bands with a repeating period of 150 A. These findings are discussed in relation with the physiological role of the epineural connective sheath in metabolic and mechanical functions.

Effect of Skew Penetration on Stress Concentration

A method of analysis is proposed by which the stress field for a skew hole can be determined from the plane-stress field of an equivalent right hole. As an application of the method, an elastic, infinite plate, weakened by the penetration of an oblique circular cylinder, is considered. The stresses are calculated at a generic point of this plate subjected to tractions at an arbitrary direction. Several particular cases are described with varying loading combinations at the lateral boundaries of the plate and degree of skewness of the hole. The results indicate a steep rise in maximum stress in terms of angle of skewness, sensitivity to Poisson's ratio, and shift of its location from the midsurface for thick plates towards the edge for thin ones. The theoretical predictions are then compared with the experimental data of photoelastic plates, shells and a steel shell model. The theoretical prediction and experimental results for both plates and shells are found to be in agreement.

Origin of pegmatites

Pegmatites of several areas are described. It is contended that their properties and relationships support Fersman's idea that pegmatites are magmatic rather than hydrothermal or metasomatic. The principal arguments are as follows: 1) contacts of the pegmatite material are sharp where it occurs in the original bides or in xenolithic fragments; 2) later K-Na metasomatism affects pegmatites and enclosing granite the same way; 3) a pegmatite body contains the same minerals, including, accessories, whether the country rock is granite, diabase or limestone; 4) graphic texture occurs in some of the dikes; 5) there is strong differentiation in thick dikes; less, in thin ones (branches); 6) method of incorporation of xenoliths in pegmatites suggests viscous melt, not aqueous solution; 7) Xenoliths in pegmatite are'only slightly altered, if at all. -- E. Ingerson.