Showing papers by "The Hertz Corporation published in 1968"
TL;DR: The cholesterol controls the fluidity of the hydrocarbon chains of the phospholipid by disruption of the crystalline chain lattice of the gel phase, and by inhibiting the flexing of chains in the dispersed liquid crystalline phase.
847 citations
TL;DR: The lecithins formed more expanded films than the phosphatidylethanolamines and this is interpreted in terms of differences in the size and orientation of the polar groups and this transition occuring in the bimolecular lamellae in water corresponds to the transition from condensed to expanded monolayer.
514 citations
TL;DR: In this article, the authors show that the contents of extracts from each horizon of twenty-six British soil profiles show distinctive patterns, independent of the residual dithionite-soluble Fe.
Abstract: Summary
Potassium pyrophosphate (0.1m) removes very little Fe from crystalline Fe oxides at pH 10, but peptizes finely divided hydrous amorphous oxides and organic matter in soils.
Fe and C contents of extracts from each horizon of twenty-six British soil profiles show distinctive patterns, independent of the residual dithionite-soluble Fe. Thus extracts of humus Fe podzols have maximum Fe and C in the B horizon, peaty gley podzol has maximum Fe in the B horizon but maximum C in the surface. These groups are differentiated from non-podzols which have maximum pyrophosphate extractable Fe and C in the surface horizon, decreasing with depth. Intermediate patterns help to quantify differences in soils of classes having properties of more than one soil group.
397 citations
TL;DR: In this article, a study consisting of acoustic measurements at fourteen sites in the London area and 1200 interviews dealing with the effects of the noise conditions prevailing at each of these sites has been carried out with the object of developing acceptability criteria for traffic noise from roads in residential areas.
222 citations
TL;DR: In this article, a method was developed for the study of starch retrogradation by differential thermal analysis using the expression θ8 = exp (-ktn), where θ = the fraction of crystallisable starch remaining uncrystallised at time t. The results indicated that the nucleation process in starch crystallisation is instantaneous in the systems studied.
Abstract: A method was developed for the study of starch retrogradation by differential thermal analysis. The kinetics of the crystallisation process were studied using the expression θ8 = exp (-ktn), where θ = the fraction of crystallisable starch remaining uncrystallised at time t. The values for the Avrami exponent (n) and the rate constant (k) were found to coincide with values previously obtained for the staling of bread, as followed by measurement of crumb elastic modulus. No difference between the time constants of gels cooled slowly and rapidly after gelatinisation was found, indicating that the nucleation process in starch crystallisation is instantaneous in the systems studied. The fact that the Avrami exponent is unity also suggests that the nucleation process is instantaneous, and that it is followed by rod-like growth of crystals.
154 citations
TL;DR: The occurrence of Endogone spores was studied in some 250 samples of Australian and New Zealand soils, and in some Rothamsted field soils; seven of the nine spore types formed vesicular-arbuscular mycorrhiza with inoculated host plants.
Abstract: The occurrence of Endogone spores was studied in some 250 samples of Australian and New Zealand soils, and in some Rothamsted field soils. The main diagnostic features of nine Endogone spore types are described, with notes on some of their developmental stages. Seven of the nine spore types formed vesicular-arbuscular mycorrhiza with inoculated host plants.
144 citations
TL;DR: The use of nuclear magnetic resonance spectroscopy for studying molecular interactions in biological membranes has been investigated using erythrocyte membrane fragments and the spectrum shows peaks which can be assigned to various groups of the lipid, sugar and protein.
134 citations
TL;DR: In this paper, the relationship between loaf specific volume and the rate and extent of staling in bread as measured by changes in crumb elastic modulus have been examined, and it was shown that the effect of changes in bread specific volume on staling characteristics is greater in bread prepared by bulk fermentation than in bread made by the Chorleywood Bread Process.
Abstract: The quantitative relationships between loaf specific volume and the rate and extent of staling in bread as measured by changes in crumb elastic modulus have been examined. The results show that loaf specific volume is a major factor in determining both the rate and extent of staling, both of which decrease in a linear manner, over the range studied, as loaf volume increases. Only two factors have been found that have a significant influence on these curves, the basic breadmaking process and the storage temperature. The influence of changes in loaf specific volume on staling characteristics is greater in bread prepared by bulk fermentation than in bread prepared by the Chorleywood Bread Process. Bread made by the Chorleywood Bread Process stales less rapidly than bread made by the conventional bulk fermentation process. The effect of loaf specific volume on the rate of staling is more marked as the storage temperature is lowered.
110 citations
TL;DR: In a Rothamsted field soil that had received different manurial treatments (no manure, dung and mineral fertilizer) for over 100 years, spore populations differed greatly.
Abstract: Some 250 Australian and New Zealand soil samples were examined. Endogone spores were usually more numerous and diverse in cultivated soils than under natural vegetation. It is suggested that the spores develop particularly under conditions of intermittent root growth. In a Rothamsted field soil that had received different manurial treatments (no manure, dung and mineral fertilizer) for over 100 years, spore populations differed greatly. The reliability of the sampling method is discussed.
103 citations
TL;DR: The levels of Krebs cycle, glyoxylate cycle, and certain other enzymes were measured in a wild-type strain and in seven groups of acetate-nonutilizing (acu) mutants of Neurospora crassa both after growth on a medium containing sucrose and after a subsequent 6-hr incubation in a similar medium, containing acetate as the sole source of carbon.
Abstract: The levels of Krebs cycle, glyoxylate cycle, and certain other enzymes were measured in a wild-type strain and in seven groups of acetate-nonutilizing (acu) mutants of Neurospora crassa, both after growth on a medium containing sucrose and after a subsequent 6-hr incubation in a similar medium, containing acetate as the sole source of carbon. In the wild strain, incubation in acetate medium caused a rise in the levels of isocitrate lyase, malate synthase, phosphoenolpyruvate carboxykinase, acetyl-coenzyme A synthetase, nicotinamide adenine dinucleotide phosphate-linked isocitrate dehydrogenase, citrate synthase, and fumarate hydratase. Isocitrate lyase activity was absent in acu-3 mutants; acu-5 mutants lacked acetyl-coenzyme A synthetase activity; and no oxoglutarate dehydrogenase activity (or only low levels) could be detected in acu-2 and acu-7 mutants. In acu-6 mutants, phosphoenolpyruvate carboxykinase activity was either very low or absent. No specific biochemical deficiencies could be attributed to the acu-1 and acu-4 mutations. The role of several of these enzymes during growth on acetate is discussed.
94 citations
TL;DR: In this article, a theory of the tensile strength of powders, incorporating the effect of powder density, particle size distribution and interparticle force, has been developed, which enables the experimental results for different size fractions of each of five materials of different chemical and physical nature to be correlated with the particle size distributions.
TL;DR: In this paper, the authors measured the line widths and relaxation times of phospholipid molecules in a variety of environments including coarse aqueous dispersions, sonicated annealing, and dissolved in organic solvents.
TL;DR: In this article, the rate-temperature equivalence principle for rubber friction and abrasion has been established for all viscoelastic processes, which holds good for all processes.
Abstract: Progress in the last few years in understanding rubber friction and tire wear justifies a survey of developments since a review of the subject in 1958. Work on fundamental of friction and abrasion has mainly evolved from conceptions formed in the earlier investigations; it had, however, not been realized that wear of tires and, indeed, abrasion on certain laboratory machines brings into play gross properties of the tire or testpiece which affect rate of wear just as much as the actual abrasion resistance of the tread compound. This new field of research has led to rationalization of road testing, and has helped to bridge the gap between laboratory and road. A report on these developments is given. Much of the work is concerned with the viscoelastic nature of rubber friction and abrasion, which has come to light through the experimentally established validity of the rate-temperature equivalence principle for these processes. This principle, which holds good for all viscoelastic processes, is brief...
TL;DR: In this paper, it was shown that the shear index n in the yield locus equation ( τ C n = σ T + 1 where τ = shear stress T = tensile strength σ = normal stress C = cohesion can be correlated with the volume surface mean diameter in microns by means of the general equation n = 1 + B (d) X where B = constant d = volume/surface mean diameter while the tensile weight T is correlated by the equation T = A( ϱ ϱ s )m where A and m = constants ϱ
TL;DR: Hexanal and trans-hex-2-en-1-al, although minor components of the secretion, also produce this effect and seem to be the first alerting pheromones identified in the Hemiptera.
TL;DR: It is suggested that because of the rapid lowering of the viscosity of its solutions by reducing agents the major, important fraction of glutenin consists of linear molecules made up of polypeptide chains linked to one another difunctionally by S.S bonds.
Abstract: It is suggested that because of the rapid lowering of the viscosity of its solutions by reducing agents the major, important fraction of glutenin consists of linear molecules made up of polypeptide chains linked to one another difunctionally by S.S bonds. When dough is stretched the natural tendency of the polypeptide chains to return to a contracted state of low free energy accounts for the elasticity. The interchain S.S bonds are essential for elasticity because inter-chain adhesion between individual polypeptide chains will not overcome the stronger intra-chain forces unless reinforced by the S.S bond. If extension exceeds the elastic limit, viscous flow occurs because steric hindrance and molecular slip will prevent a return to the original conformation. Disulphide interchange is believed to play an important part in stress relaxation. Mechanical scission of S.S probably occurs when molecules at their elastic limit are subjected to too much stress; this may explain the work maximum in the Chorleywood Bread Process. Explanations are advanced for mechanical and activated dough development and evidence in favour of the hypothesis is discussed.
TL;DR: The transition from “summer” bees, in which the hypopharyngeal glands change rapidly in size and invertase content as a bee gets older, to “winter’ bees, which at all ages have large glands, is studied.
Abstract: SummaryThe transition from “summer” bees, in which the hypopharyngeal glands change rapidly in size and invertase content as a bee gets older, to “winter” bees, which at all ages have large glands rich in invertase, progressed gradually towards the end of the summer.In summer, glands of many foraging bees were large, and in winter those of bees feeding brood contained much invertase.The visible secretion masses in the glands are probably larval food. The invertase-containing secretion was not separately visible. It could be either scanty or abundant in large visibly active glands; it was always abundant in glands that appeared to be almost completely atrophied. The latter must actively secrete invertase, since they discharged too much to have come from reserves within them.
TL;DR: In spite of the entomophilic structure of the rape flower, which is very attractive to nectar- and pollen-gathering bees, the crop gives good yields without insect pollination.
Abstract: In spite of the entomophilic structure of the rape flower, which is very attractive to nectar- and pollen-gathering bees, the crop gives good yields without insect pollination.
TL;DR: The size of a colony in spring was related directly to its size in the previous autumn, and the proportion of bees that survived the winter was similar in large and small colonies.
Abstract: Near Harpenden, Hertfordshire, brood rearing continues later into the autumn in small than in large colonies, and in colonies headed by queens of the current year than by queens of the previous year. In spring the amount of brood present increases with colony size, but there is more brood per bee in small than in large colonies. Food consumption per bee during winter decreased with increase in colony size, especially in colonies with fewer than 18,000 bees. The size of a colony in spring was related directly to its size in the previous autumn, and the proportion of bees that survived the winter was similar in large and small colonies.
ZUSAMMENFASSUNG
DIE WIRKUNG DER GROSSE VON HONIGBIENEN-VOLKERN AUF NAHRUNGSVERBRAUCH, BRUT UND LEBENSDAUER DER WINTERBIENEN
In der Umgebung von Harnenden, Hertfordshire, erstreckt sich die Bruttatigkeit bei kleinen Volkern und bei Volkern mit diesjahrigen Koniginnen weiter in den Herbst hinein als bei grosen und bei Volkern mit vorjahrigen Koniginnen. Im Fruhjahr steigt der Brutanteil mit der Grose des Volkes an, jedoch haben kleine Volker mehr Brut pro Biene als grose. Der Nahrungsverbrauch pro Biene nimmt im Winter mit zunehmender Grose des Volkes ab, besonders bei Volkern mit weniger als 18000 Bienen. Bezieht man die Grose des Volkes im Fruhjahr direkt auf seine Grose im vergangenen Herbst, dann erweist sich das Verhaltnis der uberwinternden Bienen bei grosen und kleinen Volkern als ahnlich.
TL;DR: Investigation of the loss in grain yield associated with specific levels of leaf blotch found a consistent relationship between the disease level, at growth stage 11·1 (Feekes scale), and loss in yield.
Abstract: SUMMARY
Two methods were used to investigate the loss in grain yield associated with specific levels of leaf blotch. Yields from plots sprayed with fungicide were compared with those from unsprayed plots and yields of varieties of different susceptibility to the disease were compared with one another. A disease assessment key is presented, which was used to assess the percentage laminar area of the top two leaves affected by the disease. A linear relationship between disease on the upper two leaves and yield was established. Results from nine trials showed a consistent relationship between the disease level, at growth stage 11·1 (Feekes scale), and loss in yield. The loss in yield expressed as a percentage of the yield of an uninfected crop was equivalent to approximately two-thirds of the percentage of the flag-leaf area visibly infected, or one-half of the infected area on the second leaf. The predicted loss in yield is the average of these two estimates.
TL;DR: A Czochralski crystal puller has been built to grow crystals of gallium phosphide by the liquid encapsulation technique as mentioned in this paper, which has electrical properties similar to those of epitaxial vapour grown material.
TL;DR: In this article, the authors extract six compounds which are more strongly adsorbed on to silicic acid than those previously described, and one of these compounds has been isolated by column chromatography.
Abstract: Of the antioxidants extracted from oats, 36% (by weight) consists of six compounds which are more strongly adsorbed on to silicic acid than those previously described, 1,2 One of these has been isolated by column chromatography. On hydrolysis it yields caffeic acid (2 moles), ferulic acid (1 mole), glycerol (1 mole) and long-chain ω-hydroxyacid (1 mole). The ω-hydroxyacid fraction contains the homologues, C22 (5%), C26 (64%), and C28 (31%).
The probable structures of the compounds are discussed.
TL;DR: The breakdown in size from large particles (0.5 μ-20 μ) containing extensive lamellar order to smaler particles less than 1 000 A diameter which still retain the same 66-A lameller order originally present in the coarse dispersion is confirmed.
TL;DR: In this paper, the effect of diluent flow on soot production in laminar ethylene diffusion flames has been studied by measurement of smoke points and of the rates at which soot leaves a smoking flame.
TL;DR: Changes in the intensity of the 720 cm-1 band were followed in the infrared spectra of the human erythrocyte membrane and its total lipid extract, recorded at various temperatures, interpreted in terms of the configuration of the lipid hydrocarbon chains within the membrane.
Abstract: Changes in the intensity of the 720 cm-1 band were followed in the infrared spectra of the human erythrocyte membrane and its total lipid extract, recorded at various temperatures. These changes are interpreted in terms of the configuration of the lipid hydrocarbon chains within the membrane. Effects of temperature, sonication, removal of lipids, and organic solvents on the amide I and II bands, associated with protein conformations, were also studied.
TL;DR: Sixty mutants of Neurospora crassa unable to grow on acetate as sole source of carbon, but able to utilize sucrose, were isolated and six of the genes have been mapped; no two are closely linked.
Abstract: Sixty mutants of Neurospora crassa unable to grow on acetate as sole source of carbon, but able to utilize sucrose, were isolated. On the basis of complementation tests, they were divided into seven groups, each group representing a different gene. Six of the genes have been mapped; no two are closely linked. These loci have been designated acu-1 to acu-7. Mutations at four of these loci result in poor germination of ascospores.
TL;DR: Experiments using exclusion techniques provided evidence that natural enemies which attack A. fabae on E. europaeus and on summer hosts cause the common 2-year cycle of aphid abundance, which is used as sensitive indicators of later crop infestations.
Abstract: SUMMARY
Autumn populations of Aphis fabae Scop, on the primary host Euonymus europaeus L. were little affected by natural enemies, most of which had begun to hibernate before the aphid populations developed.
The size of the population in spring was usually determined by the number of overwintering eggs on a bush. The fundatrices hatched about 3–6 weeks before natural enemies became common. The growth of large A. fabae populations was first halted by the effects of intra-specinc competition, notably by the production and departure of emigrant alatae and by adult apterae reproducing more slowly. Later, natural enemies, especially Adalia 2-punctata (L.), Syrphidae and the parasite Trioxys sp. (near angelicae), multiplied and accelerated the decline in the aphid populations, which usually disappeared in June leaving many immature natural enemies. Larval A. 2-punctata began to eat parasitized aphids and cannibalized other larvae and pupae.
The small populations of A. fabae that develop from few overwintering eggs are at greater risk from natural enemies than are large ones. Intraspecific competition still slowed population increase, because most aphids remained crowded on the few originally colonized twigs. Such populations produced very few emigrant alatae before they were exterminated by the combination of T. angelicae with specific and non-specific predators. Adult Cantharidae killed many of the aphids, especially in hedgerow habitats, where they were abundant.
Coccinellidae, Anthocoridae and syrphid larvae, and the adults of nonspecific predators, notably Cantharidae, prevented recolonization of E. europaeus throughout July and August. Leaves of E. europaeus may remain physiologically suitable for A. fabae throughout July but begin to deteriorate in August when A. fabae kept on them become less fecund.
Experiments using exclusion techniques provided evidence that natural enemies which attack A. fabae on E. europaeus and on summer hosts cause the common 2-year cycle of aphid abundance.
Individual E. europaeus differ consistently in the extent to which they are colonized by A. fabae. Conditions are discussed that should govern the choice of E. europaeus bushes on which the A. fabae populations can be used as sensitive indicators of later crop infestations.
TL;DR: In this paper, a scaling law for the conditions under which individual flames will merge, independent of the number of fires involved, and in which the height of the flames and the size and separation of the individual fuel beds scale geometrically.
TL;DR: Equations of the type dX/dt=A-rX, where X is the the organic matter in the soil, A the annual return of plant material, r the fraction of X decomposed per year and t time, have been used to represent the turnover of organicmatter in soil and their validity and limitations are discussed.
Abstract: There is little quantitative data on the turnover of soil organic matter even for parts of the world where long-term field experiments have been carried out. Comparisons of turnover under different climatic conditions, under different systems of agriculture, under different plant associations, at different pH's, in soils differing mechanical composition would be of pedological and agricultural interest. Although many turnover problems, particularly gross turnover ones can (and should) be studied by non-isotopic methods, isotopes used in conjunction with long term field experiments are potentially capable of giving quantitative information obtainable in no other way. Isotopes are particular useful under steady state conditions, and experiments under steady state conditions have the additional advantage that many sampling problems, uncertainties about constancy of plant return etc., are avoided. Long term field experiments on turnover are practicable, and should be set up in different parts of the world.
Equations of the type dX/dt=A-rX, where X is the the organic matter in the soil, A the annual return of plant material, r the fraction of X decomposed per year and t time, have been used to represent the turnover of organic matter in soil. Their validity and limitations are discussed. There is a formal analogy between turnover in an animal in metabolic balance and turnover in a soil where annual additions of organic matter balance between annual losses., and many of the isotopic techniques used in steady state metabolic studies can be applied to soil problems. Carbon-14 dating is of limited value in measuring turnover in soils but the increase in atmospheric carbon-14 resulting from thermonuclear tests has potential applications in turnover studies.