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Showing papers by "University of Hertfordshire published in 1969"


Journal ArticleDOI
TL;DR: It has been known for many years that deformation results in softening of rubber and that the initial stress-strain curve determined during the first deformation is unique and cannot be re-strained.
Abstract: It has been known for many years that deformation results in softening of rubber and that the initial stress-strain curve determined during the first deformation is unique and cannot be re...

1,004 citations


Journal ArticleDOI
TL;DR: In anaesthetized animals, salbutamol, given intravenously, was slightly less active than isoprenaline in preventing spasm of bronchial smooth muscle but was considerably less active as a cardiac stimulant and vasodepressor substance.
Abstract: 1. Salbutamol is a beta-adrenoceptive receptor stimulant. Its pharmacological actions are reduced or abolished by beta-receptor antagonists.2. In anaesthetized animals, salbutamol, given intravenously, was slightly less active than isoprenaline in preventing spasm of bronchial smooth muscle but was considerably less active as a cardiac stimulant and vasodepressor substance. Its duration of action was about 2 to 3 times that of isoprenaline.3. Salbutamol given by mouth or aerosol to conscious guinea-pigs, greatly diminished bronchospasm caused by inhalation of acetylcholine. By mouth, salbutamol was more active and had a longer duration than isoprenaline or orciprenaline without affecting heart rate. By aerosol, salbutamol was approximately 10 times as active as isoprenaline and 100 times as active as orciprenaline. Its duration of action was much longer than that of isoprenaline or orciprenaline. Only isoprenaline produced an increase in heart rate by the aerosol route.4. On isolated guinea-pig trachea salbutamol had about 1/10 the activity of isoprenaline, on isolated atria about 1/2000.

282 citations


Journal ArticleDOI
TL;DR: In this paper, the texture profile concept used by Szczesniak and her co-workers is critically examined, and several modifications are proposed, and the new scheme consists of primary, secondary and tertiary categories.
Abstract: SUMMARY: Many attributes contribute to texture, and panel tests should be so arranged that all these attributes are analyzed. The texture profile concept used by Szczesniak and her co-workers is critically examined, and several modifications are proposed. The new scheme consists of primary, secondary and tertiary categories. These terms are not used in the philosophical sense proposed by Locke. Primary attributes are analytical composition, particle size and size distribution, particle shape, air content etc. There are only three secondary attributes viz., elasticity (E), viscosity (η) and adhesion (N). The tertiary characteristics are basically the responses most often used in sensory analysis of texture. Tertiary characteristics are derived from a complex blending of two or more secondary attributes. The former can be regarded as falling within a three dimensional continuum which has the secondary attributes as coordinate axes. Consequentiy all tertiary attributes can be represented by rectangular coordinates of the form (αE, βn, γN) where α, β, and γ represent the respective magnitudes of the three secondary attributes. Since solids, semisolids and fluids have characteristic values of these attributes, it should be possible to predict panel responses from mechanical strain-time tests, which are carried out at the approximately constant rate of shear operative during mastication, and adhesion tests.

110 citations


Journal ArticleDOI
TL;DR: A decrease in the total viable bacteria in the effluent was also observed when protozoa were added to the activated-sludge plant, confirming earlier demonstrations of the importance of protzoa in the clarification of sewage effluent.

98 citations


Journal ArticleDOI
01 Mar 1969-Nature
TL;DR: Differences between species have not been sought, in spite of their importance for chemical taxonomy and their broader implications in behavioural studies and comparative biochemistry.
Abstract: MOST studies on pheromones and volatile secretions of insects, except defensive secretions1,2, have used material from unrelated species3. Differences between species have not been sought, in spite of their importance for chemical taxonomy and their broader implications in behavioural studies and comparative biochemistry.

73 citations


Journal ArticleDOI
29 Nov 1969-Nature
TL;DR: I have found three detoxification mechanisms in subcellular fractions of six strains of housefly and related these to the genetics of diazinon-resistance7,8 of the flies.
Abstract: HOUSEFLIES metabolize dialkyl phosphorothionate insecticides, such as diazinon and parathion, to the corresponding dialkyl phosphorothioic acids1,2. This reaction is thought to be controlled by gene a, on chromosome II (ref. 3), associated with low aliesterase activity4. The cleavage mechanism is reported to be in the microsomes2,5,6. I have found three detoxification mechanisms in subcellular fractions of six strains (Table 1) of housefly and related these to the genetics of diazinon-resistance7,8 of the flies.

72 citations


Journal ArticleDOI
TL;DR: It is concluded that the hydrophilic head groups of phosphatidylserine in a sonicated aqueous dispersion are readily accessible to the local anaesthetic molecule.

71 citations


Journal ArticleDOI
TL;DR: The theory of the time domain relationship between the input and output of a linear process is explained and clarified by graphical illustration in this article, and the theory of correlation method of process dynamic analysis is similarly presented.
Abstract: The theory of the time domain relationship between the input and output of a linear process is presented, and the mathematical relationships are explained and clarified by graphical illustration. The theory of the correlation method of process dynamic analysis is similarly presented. Special reference is made to the use of pseudo-random binary signals as perturbation signals, and a design procedure for crosscorrelation experiments with a pseudo-random binary perturbation signal is given. Tables listing experiments so far reported in the literature are included, and applications in the process industries and to nuclear power systems are considered.

63 citations


Journal ArticleDOI
TL;DR: In this paper, the steady-state viscosities of microemulsions were determined in a capillary viscometer, and the relative viscosity (nrel) data conformed to Nrel = exp a (δ−δ s ) 1−k(δ − Δ s) where k is a hydrodynamic interaction coefficient which depends empirically on mean particle size according to k = 1.079 + exp ( 0.01008 D m ) + exp( 0.00290 D m 2 ).

63 citations


Journal ArticleDOI
TL;DR: The operation appears to be equally effective in osteoarthritis and rheumatoid arthritis, and the cause of relief of symptoms after osteotomy is not known.
Abstract: 1. Double osteotomy was performed on 1 50 knees between 1961 and 1969. The first fifty-seven cases were assessed independently. 2. The operation of osteotomy of the upper end of the tibia and the lower end of the femur is described. it is emphasised that the osteotomy sites are close to the bone ends and well within the cancellous expansion. 3. The indications for the operation are pain and loss of function in a mobile arthritic knee joint. 4. Flexion of the knee is important during the operation to allow the popliteal artery to be moved away from bone. Arteriograms at necropsy show the danger of damaging the popliteal artery when the knee is extended. 5. The operation appears to be equally effective in osteoarthritis and rheumatoid arthritis. The proliferated synovium of the active rheumatoid knee regresses rapidly following operation. 6. The operation has resulted in relief of pain and increase in function in many knees which had no deformity. When a deformity did exist before operation recurrence of the deformity did not appear to influence the result. 7. The cause of relief of symptoms after osteotomy is not known, and it is suggested that answers to the following questions should be sought: Why are some arthritic knees painful and some not ? Why does physiotherapy relieve pain ? Why does osteotomy relieve pain? Why is double osteotomy followed by regression of synovial proliferation ? Why does osteotomy sometimes fail ? Would osteotomy of one bone (tibia or femur) be sufficient?

58 citations


Journal ArticleDOI
TL;DR: Results were obtained to indicate that AH 5183 also impaired transmission in motor nerves by a prejunctional action, probably by inhibiting uptake of choline, similar in many ways to that caused by (+)-tubocurarine.

Journal ArticleDOI
20 Sep 1969-Nature
TL;DR: The authors found that only a small fraction of the surface of the soil is responsible for the sorption of certain herbicides, whereas others found no relationship between water solubility and sorption on soil.
Abstract: PARTITION between soil and water of organic compounds that do not ionize in the pH range 4–8 is closely correlated with the soil's content of organic matter. Lambert1 and Furmidge amd Osgerby2 have expressed sorption in terms of partition coefficients between soil organic matter and water, neglecting mineral constituents. Some investigators have also reported inverse correlations between water solubility and sorption on soil whereas others have found no relationship2,3. Little is known about the mechanisms of sorption on soil, but apparently only a small fraction of the surface is responsible for the sorption of certain herbicides3. I have attempted to learn more about sorption mechanisms by studying how changes in the chemical structure of related compounds affect sorption.

Journal ArticleDOI
TL;DR: In this article, the coagulation pressure of protein monolayers is estimated from the equation for equilibrium of duplex films, where πc = γa - (γb + γab), where γα is the initial interfacial free energy and γb and ϳab are the free energies at the two surfaces of the protein monoline.

Journal ArticleDOI
10 May 1969-Nature
TL;DR: Structural features of model complexes formed between phospholipids and proteins throw light on the molecular architecture of both biological membranes and serum lipoproteins.
Abstract: STRUCTURAL features of model complexes formed between phospholipids and proteins throw light on the molecular architecture of both biological membranes and serum lipoproteins. The polymorphic phases of both synthetic and natural phospholipid–water systems have been extensively studied1–6, but little work has been reported on phospholipid–protein–water systems7–10.

Journal ArticleDOI
06 Dec 1969-Nature
TL;DR: It was found that in some steamed and irradiated soils low in available phosphorus, inoculation with Endogone spores leads to marked increases in growth of up to 300 per cent, so how far growth could be improved in unsterilized soils if seedlings were already mycorrhizal when planted was determined.
Abstract: NEARLY all soils contain fungi that can penetrate the plant roots and cause vesicular–arbuscular (v.a.) mycorrhiza; most plants become infected with them. Because of the ubiquity and wide host range of the fungi, inoculation as practised for some crops, for example, legumes with nodule bacteria and forest trees with ecto-trophic mycorrhizal fungi, has not been seriously considered for plants with vesicular–arbuscular mycorrhiza. Two recent developments suggest that it deserves consideration. At least six different Endogone species are now known to cause these mycorrhiza1,2 and there is growing evidence that their effects on the host can differ. It has also been established that in some steamed and irradiated soils low in available phosphorus, inoculation with Endogone spores leads to marked increases in growth of up to 300 per cent (see reviews by Nicolson3 and Gerdemann4), In unsteril-ized soils the response to inoculation is usually thought to be much smaller because (a) the added inoculum has to compete with the normal soil microflora, and therefore infection develops more slowly, and (b) even uninoculated plants gradually become infected from the indigenous Endogone population. It nevertheless seemed to be interesting to determine how far growth could be improved in unsterilized soils if seedlings were already mycorrhizal when planted.

Journal ArticleDOI
TL;DR: Dorylaimoidea comprising 65 valid genera is re-classified and Six new families and six new sub-families are proposed and five sub- families are upgraded.
Abstract: Crateronematidae n. fam. is proposed for the new genus Crateronema which is characterized by having a wide stoma and sclerotized anterior part of pharynx. Poronemella n. gen. is proposed for P, porifer (Loof, 1964) and P. amini n. sp. and is close to Lordelloyzema. Chrysonemoides n. gen. differs from Chrysonema in the arrangement of the labial papillae and the two genera constitute the new family Chrysonematidae. Dorylaimoidea comprising 65 valid genera is re-classified. Six new families and six new sub-families are proposed and five sub-families are upgraded.


Journal ArticleDOI
TL;DR: The use of other techniques has shown that the multilamellar structure of the phospholipids is broken down on the addition of each of these antibiotics, which may be relevant to the mode of action of some cyclic antibiotics, to the mechanism of induced ion transport across natural membranes observed with many cyclic infections.

Journal ArticleDOI
18 Jan 1969-Nature
TL;DR: It was an unexpected finding that related heterocyclic compounds were tested and two were found to have activity against all rhinovirus strains used so far.
Abstract: ISATIN 3-thiosemicarbazone is known to have antiviral activity against certain poxviruses1,2. The antiviral spectrum of 1-methylisatin 3-thiosemicarbazone, which reportedly extends to adenoviruses, may be rather broader but is still limited to several groups of DNA viruses2,3. It was therefore an unexpected finding that these compounds are also active against certain rhinoviruses. As a result, related heterocyclic compounds were tested of which several examples are shown here; two (D and E) were found to have activity against all rhinovirus strains used so far.

Journal ArticleDOI
15 Nov 1969-Nature
TL;DR: Some physical properties of and black film results with alamethicin are reported, and a study of phospholipid/alamethic in interactions is reported, which could contribute to its excitability inducing effects in experimental bilayers.
Abstract: ALAMETHICIN, a cyclic polypeptide antibiotic produced by Trichoderma viride1,2, induces “action potentials” in bimolecular lipid membranes3, and ion movements and energy-linked K+ accumulation in mitochondria4. These properties are relevant to membrane function in general and ion transport, nerve impulses and antibiotic action in particular, and more information on other chemical and physical properties of alamethicin may show how they could contribute to its excitability inducing effects in experimental bilayers. When the effects occur, phospholipids are also present. We now report some physical properties of and black film results with alamethicin, and a study of phospholipid/alamethicin interactions.

Journal ArticleDOI
24 May 1969-Nature
TL;DR: Bumblebees have nothing equivalent to the dance language of the honeybee, but the odour of the food stores of a Bombus lucorum colony can influence the choice of flower species visited by its foragers, and it seemed possible that honeybee colonies might have a similar primitive form of communication.
Abstract: WHEN a successful honeybee forager makes a food communication dance, potential recruits learn the odour of the food source both from the odour adhering to the dancer's body and from the odour of the nectar the dancer regurgitates to them; the latter is the more important when forage is distant from the hive. Conditioned foragers can be induced to revisit their food source by being touched by, or receiving food from, a companion that has just returned from the source but not danced, although contact with a dancing bee is more effective1,2. Bumblebees have nothing equivalent to the dance language of the honeybee, but the odour of the food stores of a Bombus lucorum colony can influence the choice of flower species visited by its foragers3, and it seemed possible that honeybee colonies might have a similar primitive form of communication.


Patent
06 Jan 1969
TL;DR: In this paper, a machine for the continuous manufacture of reinforced plastic pipe by winding rovings soaked in uncured or partially cured resin about a tubular plastic extrusion that advances axially over a mandrel is described.
Abstract: A machine for the continuous manufacture of reinforced plastic pipe by winding rovings soaked in uncured or partially cured resin about a tubular plastic extrusion that advances axially over a mandrel. The rovings are supplied from cakes each of which is automatically replaced when it runs out by a spare cake. Fresh cakes are also automatically supplied from a stock of cakes. Provision is also made for continuous curing and pressure testing of the pipe.

Journal ArticleDOI
TL;DR: Blood loss was sylate is effective in reducing bleeding and the magnitude of the reduction is directly proportional to the severity of the unmodifted bleeding.
Abstract: SUMMARY The haemostatic effect of ethamsylate was examined by means of a controlled, "blind" trial in which forty-three experiments were performed on a series of twenty-two pigs. The experimetal preparation consisted of a standard wound produced by means of an electric dermatome and designed to cause capillary haemorrhage. Blood loss was sylate is effective in reducing bleeding and that the magnitude of the reduction is directly proportional to the severity of the unmodifted bleeding. No effect of the drug, on pulse rate, blood pressure or platelet count was observed.

Journal ArticleDOI
18 Jan 1969-Nature
TL;DR: The ways in which lipids and proteins interact in cell membranes, in various enzyme reactions, in blood coagulation processes, and in various lipase reactions, are all subjects for research at present.
Abstract: THE interaction of phospholipids and proteins is a fundamental process of biology, and it underlies a variety of important situations. The ways in which lipids and proteins interact (a) in cell membranes, (b) in various enzyme reactions, for example, with β-hydroxy butyrate dehydrogenase, (c) in blood coagulation processes, (d) in various lipase reactions, and (e) in the structure of the serum lipoproteins, are all subjects for research at present1.

Journal ArticleDOI
12 Jul 1969-Nature
TL;DR: In this paper, the nature of the crystal edge of micas was found to affect the rate of alteration of the micas in natural conditions, and it was shown that micas may alter less rapidly than laboratory investigations of ground or cut material suggest.
Abstract: WHEN micas weather in the soil, their interlayer potassium is replaced by a hydrated cation, and a swelling mineral resembling vermiculite is formed1. Although this natural process may be simulated in the laboratory2,3,9, we have found evidence to suggest that micas may alter less rapidly in natural conditions than laboratory investigations of ground or cut material suggest. Our results show that the nature of the crystal edge affects the rate of alteration of micas.


Journal ArticleDOI
TL;DR: It is shown that the reflectivity does not depend on the particularRefractive index variation within the film but is, to a good approximation, determined only by the average refractive index and total thickness of the film.

Journal ArticleDOI
TL;DR: Mumtazium n.
Abstract: Mumtazium n. gen. belongs in Utahnematinae Siddiqi, 1969 and is characterized by having small amphids with oval apertures; large, asymmetrical spear bearing dorylaimid extension; muscular oesophagus; opisthodelphic gonad and a long, filiform tail. M. mumtazae n. sp. is described from soil in Papyrus Swamp, Namulonge, Uganda, and is the only species in the genus. Laimydorus n. gen. is proposed to accommodate those species of Dorylaimus sensu lato which lack longitudinal ridges over the body. It differs from Mesodorylaimus in having a double spear-guiding ring, longitudinal vulva; elongate, multicellular ovaries; and males having numerous contiguous, supplementary papillae and pre-rectum extending well beyond the region of the supplements.

Book ChapterDOI
TL;DR: In this paper, a simple theoretical model for the processes of photon absorption and subsequent electron emission is presented, and the photoelectric yield of a photocathode of this material from a fundamental theoretical standpoint.
Abstract: Publisher Summary This chapter provides an overview of gallium arsenide thin-film photocathodes. Many experimental GaAs–Cs photocathodes have been prepared in recent years by cleaving, under vacuum, a piece of acceptor-doped single-crystal gallium arsenide. A little cesium is then allowed to condense on the freshly exposed face, which, when illuminated, yields a very high photocurrent. Such a photocathode is thus many times more efficient than the multialkali type with a sensitivity extending into the longer wavelength region of the spectrum with high efficiency. The long-wavelength threshold for GaAs is approximately 0.9 μm (1–4 eV), but sensitivity can be further extended toward 1 μm by the use of semiconducting compounds with slightly smaller energy bandgap. In the course of the experimental work, it has been shown that GaAs layers can be deposited on polished sapphire substrates. Some of these layers have then been caesiated to provide photocathode emission efficiencies comparable with present commercial devices. As the semiconducting properties of GaAs are relatively well understood, it is possible to consider the photoelectric yield of a photocathode of this material from a fundamental theoretical standpoint. This chapter examines a simple theoretical model for the processes of photon absorption and subsequent electron emission.