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The technique of microhardness measurements using diamond indenters is outlined and assessed for its potential use in quantifying bonding changes and studying reactions in nonstoichiometric crystals. Results are presented for both Vickers and Knoop hardness values on {001} and {011} crystal planes of cubic sodium tungsten bronzes, NaxWO3, with x in the range 0.5 to 0.75. The Knoop data show that in only one direction, 〈110〉 on {001}, is the hardness sensitive to changes in composition. Hardness in the 〈110〉 directions and the degree of anisotropy increase as the sodium content of the bronze increases. All the crystal faces examined showed marked anisotropic behavior, with 〈110〉 being about 50% harder than 〈100〉 on {001} faces, while on {011} planes hardness increases in the sequence 〈100〉:〈211〉:〈111〉 ≈ 〈011〉. Hardness results from isomorphous and isoelectronic ReO3 are considered with the NaxWO3 data to show the dominant role played by Na+WO3 matrix interactions in determining the properties of these materials. The results are discussed in terms of current bonding theories for bronzes.

The electronic expansion factor for bronze phases with the perovskite structure are derived from a wide variety of literature sources and shown to fit a curve when plotted against the Ahrens ionic radius of the non-network-forming cations. Examples are given which show how the curve can be used to characterize and compare bronze-like phases.

Potted blackcurrant plants subjected to moisture stress following harvest produced 50% less total fruit yield in the following season than plants which received regular irrigation. The factors which contributed to this effect were a reduction in the numbers of productive buds, flowers per bud and fruit set. An increase in seed number per fruit in response to the stress suggested that reserve carbohydrates accumulated during the autumn may have been the controlling factor in fruit set. Bud-burst in the stressed plants was both early and uneven, radial growth was reduced, and there was no evidence of starch accumulation at the onset of dormancy. All plants received the same irrigation treatment in the spring following treatment, and there was no significant difference in fruit size except for a few positions at the distal end of the strig. Fruit on stressed plants in this case were the smallest.

The reaction of the cubic sodium bronzes, NaxWO3, with powdered iron metal has been studied by heating samples in vacuo and also at high pressure. Evidence for reaction is found at unexpectedly low temperatures. The reaction is an overall reduction which proceeds via an increase in the sodium content of the bronze phase up to some temperature-dependent limiting composition for which x < 1. The existence of this limit, its temperature dependence, and the identity of the other products of reduction have been explained in terms of the partial oxygen pressure of the system. The course of the reduction has been followed through the evolution of the bronze lattice parameter and a reaction mechanism is postulated. No evidence of significant incorporation of iron into a stable cubic sodium bronze phase has been found.

Electron microscopic observations of microstructure, together with studies of the evolution of X-ray and electron diffraction patterns, have been used to provide mechanistic information on the dehydration of boehmite to γ-Al 2 O 3 . Firing boehmite in air at 400°C produces slow development of a fine, lamellar, porous microstructure, oriented parallel to (001) γ , the dimensions of which are consistent with the loss of one-quarter of the oxygen atoms of the boehmite lattice. The mechanism proposed for the dehydration is controlled by diffusion in a direction determined by the hydrogen bond chains in the boehmite structure and involves countermigration of the Al cations and protons with crystallographic formation of voids in a coherent cubic close-packed matrix. Final reorganization to give the spinel structure of γ-Al 2 O 3 is suggested to involve gradual filling of the tetrahedral cation sites.

The technique of parallel plate rheometry has been used to study the viscosity-temperature characteristics of candidate glasses for use in infrared transmitting optical fibres.

The interaction of cured maleic anhydride polyester resins with a range of organic solvents has been studied by 13 C-NMR techniques. Solvent associated with the polymer exhibits chemical shifts different from those of the free solvent, particularly for carbonyl species in solvents such as methyl ethyl ketone, acetone and methyl acetate. The lower the apparent cross-link density of the resin the greater is the perturbation of the solvent chemical shifts. The 13 C spin lattice relaxation times are shortened relative to the free solvent, and the bound solvent has a higher melting point than free solvent. The rate of swelling of the cured resins in particular solvents can be studied using a kinetic NMR program.

Alkyllead compounds have been analysed in road drainage water samples collected during seven storm events using a sensitive gas chromatography-atomic absorption technique. The most commonly observed alkyllead species were tetraethyllead, triethyllead and trimethyllead. Similar compounds were also observed in rainwater collected at the site, but not in road surface dust or bottom sediment from the drainage channel. In all samples analysed the concentration of alkyllead was

A time-temperature study has been made of the system: γ- AlOOH (boehmite) Al 2 O 3 . The isothermal TTT diagram produced demonstrates the course of the transformation sequence, which involves a number of metastable transition alumina intermediate phases. This type of treatment allows calculation of kinetic parameters for the various transformation processes, and these may be correlated with the mechanisms operating. Kinetic aspects of variations in microstructure and crystal structure have also been studied. In particular, the progress of cation migration processes involved in the transformation γ → δ-Al2O3 has been followed in terms of the continuous variation of the spinel subcell parameters.

Measurements are reported of the temperature sensitivity of optical fibre path length over a broad temperature range for a number of fibre types.

Hydrochlorothiazide (HCTZ), ethacrynic acid, furosemide and HP-522 were studied in various clearance experiments in the dog. all four diuretics were more active saluretics during hydration studies. Only HP-522, ethacrynic acid and furosemide impaired T C H 2 O formation. Pretreatment of the animals with indomethacin, 5 mg/kg, i.v. significantly attenuated the diuretic and saluretic activity of HP-522. HP-522 was shown to lower plasma uric acid after chronic administration to chimpanzees at 10 mg/kg, p.o. for 10 days. Results from this study suggest that HP-522 appears to be a loop diuretic with at least one site of action in the medullary ascending limb of Henle's loop.

A reciprocating abrasion testing machine was used to measure the mutual abrasion of light-cured composites and clasps in vitro . Composite specimens were produced by packing the material into hemispherical wells in a polytetrafluoroethylene block, light-curing for 20 seconds and conditioning in distilled water for one week. The composites tested included ultrafine, hybrid and conventional types. Nine clasp types were studied including cast and wrought, round and half-round, cobalt-chromium, stainless steel and gold. The tests were carried out at 37 °C. The vertical overlap (undercut) of composite and clasp was set at 0.25mm. Ten specimens were subjected to 14,500 traverses in each test Abrasion of composite was measured as weight loss and reduction in thickness of the specimens, while abrasion of clasps was measured as weight loss. Abrasion of the composites was greatest for the conventional type and least for the ultrafines, but in all cases the changes were small and unlikely to impair the clinical performance of clasps during several years' usage. The abrasion of the clasps by conventional composite was considerable and would be expected to cause a significant reduction in retention clinically.

The paper demonstrates that in solving the problem of radiative transfer in an isothermal slab with Rayleigh scattering, the modified double-interval method gives the first iterates of intensity moments of accuracy comparable with the kernel approximation method.

A probabilistic model for the resolvent kernel, for the integral equation arising in the case of radiative transfer in a non-coherent, isotropically-scattering, inhomogeneous spherical-shell medium, has been proposed.

A three-year study, combining visual censuses with mist netting and banding, was conducted along a one and a half mile traverse in an area of wet sclerophyll forest in the Brindibella Range, near Canberra. Of the 63 species recorded, 30 per cent. were casual visitors, and one species was a winter resident. A total of 1,720 birds and 35 species was banded, of which 426 (25%) were retrapped, and 206 (12%) were retaken in a subsequent breeding season. The avifauna of the region area studied is strikingly similar to that of the upper Snowy River region in Victoria, and it is suggested that, ecologically, there is little or no gap between the two.

A probabilistic model of the resolvent kernel for the integral equation arising in diffusion problems in nonhomogeneous, isotropically scattering, spherical-shell media is proposed. An analogue of the X and Y functions of Chandrasekhar is given for the spherical-shell geometry.

F OLLOWING the introduction of the nitrogen mustard compounds into cancer chemotherapy in 1946, an intensive effort was made to develop agents of greater therapeutic efficacy. More than 600 new compounds containing one or more active chloroethylamine groups attached to aliphatic, aromatic, sugar, amino acid, antimalarial and other carriers were synthesized and tested in screening programs. Chemical studies showed that different mustard derivatives reacted under mild conditions in aqueous solution, such as would prevail in vivo, to unite with important functional groups present in proteins and nucleic acids [I-3]. The chemical reactivity of various compounds generally paralleled their biologic activity. The latter included cytotoxic alterations, chromosome changes, mutations, carcinogenesis and inhibition of tumor growth. To date about thirty different nitrogen mustard compounds have been given limited or extensive clinical study. The most important of these are perhaps the original methyl-bis@chloroethyl)amine (HNZ, Mustargen@) and triethylene thiophosphoramide (Thio-TEPA, TSPA) both of which must be administered parenterally. The first mustard derivative suitable for oral administration was triethylene melamine (TEM), now replaced in large part by chlorambucil (CB 1348, Leukeran@) which has greater chemical stability in the intestinal tract and solubility properties that favor absorption and regularity in dosage effect. It now appears that most of the potent mustard derivatives have a basic chemical similarity and possibly the same mechanism of action. The most active compounds have two or more ethylene-imino rings in the native molecule, or have structures readily converted into such under physiologic conditionr. By reactions involving a

There has been a growing interest in the conditions under which a reactive two-phase mixture can thermally ignite. In this paper, we consider radiative ignition of carbon particles suspended in air and contained between two parallel walls at different temperatures. Although the air is considered transparent to radiation, the carbon particles actively absorb, emit, and scatter the radiation. A similar study was done by Baek [1] where the numerical models did not include the scattering term. Inclusion of the scattering process leads to a set of simultaneous integro-differential equations where the integral term contains the singular exponential function E1(x). The coupled equations are solved numerically to study the effects of different physical and radiative parameters on the ignition times of the carbon particles. Our results compare very well with Baek [1] when there is no scattering. The main objective of this paper is to present an efficient numerical scheme to solve the coupled equations with the singular kernel when the scattering process is included.

Summary SLX4, a scaffold for structure-specific DNA repair nucleases, is important for several types of DNA repair. Many repair proteins bind to sites of DNA damage, resulting in subnuclear “foci,” but SLX4 forms foci in human cells even without DNA damage. Using several approaches, we show that most, but not all, SLX4 foci localize to telomeres in a range of human cell lines irrespective of the mechanisms used to maintain telomere length. The SLX1 Holliday-junction-processing enzyme is recruited to telomeres by SLX4, and SLX4, in turn, is recruited by a motif that binds to the shelterin subunit TRF2 directly. We also show that TRF2-dependent recruitment of SLX4 prevents telomere damage. Furthermore, SLX4 prevents telomere lengthening and fragility in a manner that appears to be independent of telomere association. These findings reveal that SLX4 plays multiple roles in regulating telomere homeostasis., Graphical Abstract, Highlights • The SLX4 DNA repair complex binds to telomeres in different human cell lines • The SLX4 scaffold protein has a TRF2-binding motif responsible for telomere localization • SLX4 also has localization-independent roles at telomeres, SLX4 is a scaffold protein that regulates several DNA repair endonucleases and forms subnuclear foci in human cells that Rouse and colleagues identify as telomeres. SLX4 is recruited to telomeres by a motif that interacts with the shelterin subunit TRF2. Mutations in this motif prevent SLX4 from localizing at telomeres and cause telomeric DNA damage in human cells. SLX4 also has localization-independent roles at telomeres, such as preventing telomere overlengthening.

Treatment of 2-year-old blackcurrant bushes, at the early grape stage of flowering, with a 0.5% v/v spray of DEPEG prevented abscission of flowers following exposure to a simulated frost of −2°C for 3 hours. Untreated bushes subjected to the same low-temperature treatment suffered a 25% reduction in fruit set.

The presence of the posterior auricular myogenic reflex was investigated in healthy subjects. Click stimuli were delivered alternately to each ear and both ipsilateral and contralateral responses were recorded simultaneously. Smiling and head down position increased the number of responses. With this method, in contrast to previous findings, it was possible to demonstrate bilateral auditory reception in 89% of the 45 subjects studied.

A scheme for obtaining the resolvent kernel of the integral equation for radiative transfer problems in an isotropically scattering sphere is proposed. Unlike the earlier attempts, the spherical problem is not transformed to its plane-parallel analogue.

Rats fed a restricted diet during gestation and lactation gave birth to pups with about 60 % the normal birthweight. Maintaining the undernutrition after birth reduced the rate of growth of the pups so that their body weights were only 40 % of control at PN7. Soleus and lumbrical muscles in these animals had reduced numbers of muscle fibres, and quantitative examination of embryonic muscles revealed that this was due solely to a decreased formation of secondary myotubes; the number of primary myotubes remained normal. Undernutrition did not affect the number of motoneurones surviving normal developmental death. Restoration of normal dietary intake on E21, one day before birth, did not correct the deficit in muscle fibre numbers in soleus muscles examined when the animals reached one month of age. Development of the lumbrical muscle lags behind the soleus and unrestricted feeding from E21 onwards allowed a normal number of fibres to develop from this time on, although the initial deficit was never restored. These experiments define a critical period in muscle development during which the potential maximum number of secondary myotubes is determined.

Techniques are described for the physico-chemical speciation of trace metals in air particulates, street dusts and roadside soils, and in freshwater samples. X-Ray powder diffraction is shown to be of application to air particulates and street dusts, but with far greater value in the former instance. Street dusts and roadside soils are best characterized by a sequential selective extraction procedure. A detailed experimental scheme for speciation of trace metals in freshwater samples is described, together with its application to a sample of highway drainage water. The shortcomings of this and other reported schemes are highlighted.

We point out an error in a recent paper by Lerche and Low [3] and show that the claimed temperature inversion with a local maximum at the centre cannot take place in their model where the radiative rate of cooling is of the form ϱS(p), ϱ being the density and S(p) a monotonically increasing function of the pressure p.

A modified method of plaster casting which has been adopted for use in the Federation of Malaya has given excellent results for impressions in soils ranging from very soft to hard. Moreover it has been found that Police Officers who had had no previous experience of the preparation of casts produced a completely satisfactory cast at their first attempt, after watching a single demonstration of the method.