bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of surface treatment effects in galvanizing iron single crystals
Authors: Ruddle G E , Sebisty J J
Published: March 2018

Single crystals of iron with basic low-index surface orientations were given various pretreatments to produce a range of surface roughness and hardness conditions and then galvanized in pure zinc in a purified hydrogen atmosphere. Significantly different reaction
effects previously found on electropolished (110), (100) and (111) surfaces of commercial single crystals were confirmed in tests involving pretreatment by thermal faceting and mechanical polishing. A relationship between galvanizing reactivity and crystallographic orientation of the iron surface
was thereby more conclusively established. Increasing the roughness of the crystal surfaces by grit blasting, and to a lesser extent by chemical etching, significantly reduced the dependence of the reactivity on crystallographic orientation. Fine surface irregularities and larger-scale uneveness,
especially as produced by grit blasting, in combination with the growth habit of the iron-zinc alloy layers, were the predominant factors determining the galvanizing behaviour. Surface work-hardening by the mechanical polishing and grit-blasting pretreatments had no apparent effect on the
galvanizing reaction.
Geochemical investigation of oils in the western Canada tar belt
Authors: Montgomery D S , Clugston D M , George A E , Smiley G T
Published: March 2018

In this investigation the hydrocarbons and sulphur compounds in the gas oils of the Athabasca, Cold Lake and Lloydminster heavy oils have been studied by a combination of liquid, gas-liquid and gas-solid chromatographic - techniques coupled with mass
spectrometry. The results were compared with those for the Medicine River oil which is lighter, thermally mature and lies in a reservoir of the same geological age. The distillates were fractionated into hydrocarbon types (i.e. saturates, mononuclear, binuclear and polynuclear aromatics). This
allowed a comparative study of the normal alkanes and isoprenoid hydrocarbons, pristane and phytane, in the C 16 to C 19 range of the saturates. Also the structural changes in the aromatic hydrocarbon types, as indicated by both gas chromatography coupled with mass spectrometry, have been followed
up. The results were interpreted geochemically with reference to the thermal and biological aspects of degradation. It is quite clear that these oils are closely related although there are some distinct differences. The number of isomers of the sulphur compounds appear to be low in comparison with
the number of possible isomers, suggesting some selective mechanism of formation.
Comparison of notch-ductility of welds made by various processes in structural steels
Authors: Campbell W P
Published: March 2018

Several specimens, welded by various processes/procedures in 3/4-in. thick OSA C40.8 Grade B steel, were examined by Charpy and drop-weight testing to evaluate the notch ductility at the weld centre-line. The welding processes/procedures employed were among those
which are or could be employed in construction of ships and other structures. Marked differences in notch ductility were found but there appeared to be no rational correlation between the Charpy and drop-weight results. AU of the processes/procedures involving electrodes, electrode/flux, or
electrode/shielding gas combinations, for which OSA or AWS specify certain Charpy requirements were capable of meeting these requirements. More stringent Charpy requirements which have been required in naval construction were met by some of the processes/ procedures. No correlation was found between
notch ductility and the proportions of coarse or refined weld microstructures contained within the test bars. Some limited bulge testing was performed which showed that good bulge performance could be obtained in the absence of significant notches on the weld or plate surface despite the fact that a
relatively low order of notch ductility was indicated by Charpy impact testing.
Magnesium content effect on properties of binary aluminum-magnesium alloys
Authors: Pollard W A
Published: March 2018

In spite of many years of experience in casting the aluminum-10 per cent Mg alloy G10, difficulties owing to inconsistent properties were still encountered from time to time. In particular, G10 made using normal purity materials sometimes gave properties (in
separately cast-to-shape test bars) which, although usually above minimum specified values, were considerably lower than those obtainable by apparently identical foundry practice. Thus, the higher level of properties would be about 50,000 psi ultimate tensile strength and 30 per cent elongation,
whereas the lower level would be about 46,000 psi ultimate tensile strength and 10 to 16 per cent elongation. In aluminum-10 per cent Mg alloy made up from super purity aluminum, however, the properties obtained were consistently high. They usually equalled or exceeded the higher values,- as
mentioned for normal purity alloys. It was shown that, at least in some cases, the low properties obtained on test bars of normal purity could be connected with the presence of layer porosity in the gage length. This phenomenon has been shown by Jay and Cibulal to occur in these alloys when the
magnesium content falls below a certain critical value. Thus, although several other possibilities were recognized and were shown to be important in certain cases, the main part of the work to be reported was a comparison between the effects of varying magnesium content and casting shape
(cast-to-shape test bars and test bars cast from heavily chilled sand cast plates) on binary aluminum-magnesium alloys made from normal and high purity materials.
A brief study of nickel-rich alloys of the Ni-Hf-C and Ni-Zr-C
Authors: Briggs D C
Published: March 2018

A brief study has been made of the incidence, form and stability of carbides of hafnium and zirconium in a nickel-base system. Alloys were studied in the Ni-Hf-C system up to 1 at. % C and 1 at. % Hf and in the Ni-Zr-C system up to 1 at. % C and 1 at.
% Zr. In each system a second phase was found that was extracted electrolytically and identified by X-ray diffraction techniques as a monocarbide of the reactive metal. Both HIC and ZrC were found to lack stability with changes in temperature; both ternary systems exhibited mild ageing
response.
The effect of test bar variables on the mechanical properties of magnesium casting alloys
Authors: Couture A , Meier J W
Published: March 2018

The effect of machining on the tensile properties of magnesium alloy test bars was investigated. Although some of the differences in property values were found to be statistically significant, they were of the same order as differences that are observed between
melts of the same composition. The results showed that the mechanical properties obtained from substandard test bars may be significantly different from those obtained on standard test bars. The study showed that results obtained on round test bars were significantly higher than those obtained on
flat test bars cut from the same parts of the castings. A comparison of 0.1% and 0.2% yield strength values, obtained on test bars of various magnesium alloys, showed that the linear relationship between these two values is different for most of the alloys and tempers investigated.
Similarly, linear relationships between the elongation values used in North America (4D), in Great Britain (3.5D) and in Continental Europe (5D) were found for the alloys investigated.
Study of as-rolled carbon steels over ranges of uranium sulphur and carbon contents
Authors: Faurschou D K
Published: March 2018

Certain ad hoc studies of uranium in carbon steels at the Mines Branch have been complemented and clarified by statistically designed and analyzed studies. The results indicate that uranium has a very limited potential usefulness as an alloying element in ferrous
metallurgy. Uranium has more potential as a scavenger and sulphide former. A factorial set of as-rolled carbon steels having four uranium levels (nil, 0.15, 0.3 and 0.6%), three sulphur levels (0.006, .0.030 and 0.14%) and two carbon levels (0.14 and 0.34%) was tested to assess the
influence of uranium on impact characteristics, active-state corrosion resistance, stress-corrosion resistance, machinability, microstructure, and isothermal transformation of austenite. The sulphur and carbon levels were introduced in anticipation of interaction effects with uranium as well as for
hidden replication. Uranium was always detrimental in progressively raising Cv fracture-appearance transition temperatures. However, only uranium contents exceeding 0.15% were inherently detrimental to absorption of impact energy. At the highest sulphur level, and particularly in transverse
tests, uranium beneficially raised the curves of Cv impact energy versus temperature. The rates of active corrosion in 5% HG 1 and H2SO4 were significantly but marginally reduced by uranium. Accelerated stresscorrosion results indicate some improvement related to the presence of 0.09%
uranium. Uranium in amounts sufficient to globularize sulphides did not significantly affect machinability. Uranium makes possible the production of ultra high sulphur steels having good transverse impact toughness. In carbon steel, uranium refined the as-cast macrostructure, promoted the formation
of degenerate pearlite and slightly delayed the transformation of austenite, but had almost no effect on tensile properties. The factorial design of the impact test program permitted quantitative determination of the effects of sulphur and carbon on Cv 15 ft-lb and Cv 50% cleavage transition
temperatures.
Computer programs for x-ray crystallography part ii: program for diffractometer angle settings
Authors: Gabe E J
Published: March 2018

This program calculates the three setting angles for a 4-circle diffractometer in the bisecting position o). It is applicable to any system, and any type of systematic absence may be allowed for. The required angles may be calculated for any segment of reciprocal
space.
The growth of arsenopyrite single crystals by the closed-tube iodine vapour transport technique
Authors: Fushimi S , Webster A H
Published: March 2018

Growth of arsenopyrite crystals was attempted by the closed-tube iodine vapour transport technique. It was necessary to choose the conditions Of synthesis properly, or else loellingite and pyrrhotite would form in a ssociation with arsenopyrite. Indeed, the
transported products always contained at least a trace of loellingite or pyrrhotite. Small but fairly Well-shaped arsenopyrite crystals with dimensions up to 0.3 x 0.1 x 0.1 mm Were obtained. It has not been possible, up to the present time, to obtain large single crystals: the product has generally
consisted of agglomerated, dendritic crystals with dimensions of up to 2 mm.
A comparison of thermal and catalytic hydrogenation as a preliminary step in the refining of Athabasca bitumen
Authors: Cameron J J , O'Grady M A , Parsons B I
Published: March 2018

The report describes a laboratory-scale investigation of thermal (noncatalytic) and cetelytic hydrogen treatment processes for converting the residuum material (+990°F) in Athabasca bitumen to distillable hydrocarbon fractions. The experiments were made in
the liquid phase, using a conventional flow apparatus with a bottom-feed pipe reactor at pressures from 500 to 3500 psi. the rate of accumulation of sludge (combined tar, coke, and mineral matter) in the reaction vessel was greatest at high conversion levels and low pressures. Continuous operation
was not possible at 500 psi, but at 1000 psi the concentration of residuum (including clay) could be reduced to 18-207 without serious difficulty. Considerable gas formation occurred at all pressures in the thermal experiments and at low pressures in the catalytic system. It was only at high
1)4ssures that the catalyst suppressed gasification relative to the conversion °f the residuum, resulting in a marked increase in the yield of liquid product. Maximum permissible extra cost for catalytic processing, compared to thermal hydrocracking (capital cost plus catalyst), is estimated at
25-30abbl.
The effects of furnace atmospheres on the sintering behaviour of uranium dioxide
Authors: Webster A H , Bright N F H
Published: March 2018

The properties of compressed uranium dioxide shapes have been examined after sintering in atmospheres of hydrogen, nitrogen + hydrogen, argon, wet argon, argon + oxygen, nitrogen, wet nitrogen, nitrogen + oxygen, and steam over the temperature range 1200° to
1500°C. Attention has been given particularly to the control of the non-stoichiometric oxygen in the oxide before, during, and at the completion of the sinte ring. It has been shown that the presence of non-stoichiometric oxygen up to a certain limit is desirable in the oxide to be sintered,
and that it is also desirable that this non-stoichiometric oxygen should remain in the oxide while the sintering is taking place if it is desired to achieve good sintering at relatively low temperatures. However, the excess oxygen should be removed to yield an essentially stoichiometric oxide on
cooling in order that the product may have satisfactory characteristics when used as a fuel element. The atmospheres listed above have been examined with a view to achieving control of the non-stoichiometric oxygen at the various stages, and a recommended procedure to achieve the desired result has
been outlined. Use has been made of the published thermodynamic data for the uranium dioxide/oxygen system in interpreting the results and in forecasting suitable sintering conditions.
The chemistry of manganese deposits
Authors: Trost W R
Published: March 2018

A new geochemical approach has been developed for relating the chemical composition of North American manganese deposits to the igneous rock from which they originated. The approach consists of specifying the nature and composition of amenable source rocks; of
devising a leaching cycle during which certain constituents of the rock are solubilized; of specifying the conditions under which the solubility products of carbonate, oxide and related compounds are exceeded; of specifying the order and association in which the compounds would be precipitated; and
of specifying the changes to be expected in aging of the deposit. The theoretical predictions agree well with observations on known deposits.
Voltaic cells in fused salts part i. the silver-silver chloride, cobalt-cobaltous chloride system
Authors: Flengas S N , Ingraham T R
Published: March 2018

A reversible silver - silver chloride reference electrode for use in melts at high temperatures has been developed. It was found that the solution of silver chloride in an equimolar mixture of KCI-NaC1 melt is ideal for the range of concentrations studied, i.e.
1.0X10-3 to 6.0X10-2 mole fraction of AgCl. The electromotive force of the voltaic cell Co I CoCl2 (x2 ) AgCI (xi) I Ag, I KCI-NaCI (1/1 mole) II KCI-NaCI (1/1 mole) I in which the half-cell to the right contains the above-mentioned reference electrode, was measured as a function of CoC12
concentration. The applicability of the Nernst equation to this system vas established. Deviation from ideality was observed in the case of the solution of CoCl 2 in the melt solvent, and this was attributed to the formation of a complex. The dissociation constant of this complex was calculated as
4.50 X10-2 at 710° C. The effect of temperature on the electromotive force of this cell was also measured, and the heat of the cell reaction in the presence of solvent (Co + 2AgCI --> CoCl2 2Ag) was calculated from the data as 22.8±1.3 kcal. The thermodynamic significance of the
standard electrode potential of the Co-Ag voltaic cell, derived experimentally as 0.324 volt, is discussed briefly
Experimental electric smelting of manganese ores part 1
Authors: Campbel R A , Viens G E , Rogers R R
Published: March 2018

The electric smelting of five low-grade Canadian manganese ores has been investigated at the Mines Branch, Department of Mines and Technical 'Surveys, Ottawa. Ferromanganese, silicomanganese, and spiegeleisen were produced by special smelting processes from these
ores since the latter were too low grade to be treated by conventional smelting methods. In one case the results were considered to be sufficiently promising to justify the construction of a pilot plant, by the Company concerned, for the further development of the process
Mechanical and structural changes during the deformation of copper by fatigue
Authors: McGrath J T , Thurston R C A
Published: March 2018

The structural changes which take place in polycrystalline copper under the action of alternating cycles of torsion stress were studied, using the optical microscope and the X-ray diffraction camera, and an attempt was made to correlate them with changes in the
shape of the cyclic stress-strain curve. It was found that the period of work-hardening was less than one per cent of the fatigue life, and that persistent surface markings, which are assumed to be incipient or actual microcracks, occur upon completion of work-hardening. X-ray diffraction patterns
revealed considerable grain distortion at the completion of work-hardening in specimens cycled at a high strain amplitude This distortion became progressively less as the strain amplitude decreased. Mechanisms for the completion of work-hardening and the formation of microcracks are
discussed.
A study of the Athabasca bitumen from the Abasand quarry, Alberta, Canada
Authors: Boyd M L , Montgomery D S
Published: March 2018

A brief summary of the early history and development of the Athabasca bitumen is given as a background to the present chemical research. The physical properties of the bituminous sand being studied are tabulated; these include elementary analysis, ash content,
molecular weight, density at 20°C, the emission spectra of the ash of the bitumen, and the chemical composition, screen analysis and emission spectra of the sand. Preliminary chromatographic experiments on the bitumen are described to illustrate the necessity for separating the asphaltene
components before fractionating the remainder of the bitumen. The large-scale extraction experiments are described, in which the asphaltene fraction and the pentane extract were prepared. The following properties of the asphaltene fraction were measured: ash content, elementary analysis, molecular
weight, density at 20°C, refractive index at 20°C, emission spectra of the ash, and the infra-red spectrum. A quantitative estimate of the aromaticity is made from the infra-red spectrum. The asphaltene fraction is characterized by the application of van Krevelenes structural analysis
system and also by two new methods devised by the authors., The chemical structure is expressed in terms of five structural groups, and an estimate is made of the degree of condensation of the aromatic rings by determining the number of fused ring and non-fused ring junction carbon
atoms.
Non-metallic thermal storage media
Authors: Svikis V D
Published: March 2018

To evaluate their suitability as thermal storage media, seven ceramic products, thirteen ceramic bodies, twenty-two rocks and fifteen ceramic-rock bodies -- all low-cost non-metallics -- were submitted to determinations of thermal properties such as specific heat
and heat capacity per unit volume. For this work a large calorimeter and a special electric furnace were designed and constructed. The mean specific heat determinations were made by the method of mixtures in a calorimeter, using water. The procedure is described in detail, The heat capacities per
unit volume were calculated from the densities and mean specific heats of the materials examined. .The results are summarized and tabulated. The results indicate that 'highly calcined' pure alumina (over 997. Al203) and dead-burned magnesia (over 93 7, MgO) have the best heat capacities of the
ceramic products and rocks examined. Two-, three-, and four-component bodies from ceramic products or ceramic products and rocks, bonded with Ciment Fondu, are economically more attractive but have lower heat capacities than calcined alumina and dead-burned magnesia. However, bodies consisting of
dead-burned magnesite clinker, fireclay brick, and building brick are adequate thermal storage media. In certain cases, the fireclay brick and the building brick in these body compositions can be successfully replaced by rocks, such as sandstone, quartzite, and granite. It is concluded that
materials and material compositions rich in dead-burned magnesia are excellent low-cost thermal storage media. Although pure alumina has high heat capacity, its cost is almost twice that of dead-burned magnesia,meking it expensive for use as a thermal storage medium.
The effect of the mineralogical composition of Whitemud formation clays on their utilization
Authors: Brady J G
Published: March 2018

Such ceramic properties as plasticity, drying behaviour, and firing behaviour of a wide variety of clays from the Whitemud formation of southern Saskatchewan and southeastern Alberta are investigated. The relationship between the mineralogical composition
(determined by X-ray diffraction and differential thermal analysis) and possible commercial utilization is discussed. Typical samples of good-quality stoneware clays, ball clays, fire clays and Kaolinized sands suitable for a wide variety of products contain principally kaolinite and quartz and
frequently mica, feldspar and montmorillonite. Fine particle kaolinite and montmorillonite have the greatest effect on increasing the plasticity of these clays while quartz, feldspar and coarse mica reduce their plasticity. The most refractory clays contain principally kaolinite, quartz'and
sometimes a small quantity of gibbsite. Mica occurs as the clay mineral "'Mite" or as coarse mica particles such as muscovite. Mica, feldspar and montmorillonite lower the refractoriness of the Whitemud clays. Differential thermal analysis indicates that there should be no problem in firing the
Whitemud clays. Contaminating minerals such as carbonaceous material, siderite, jarosite and gypsum should not prove troublesome, because they are present in minor quantities. Usually, the composition of the Whitemud clays results in a medium to long firing range, whereas in many other Canadian
clays the firing range is very short.
A study of the Athabasca bitumen from the Abasand quarry, Alberta, Canada part iii: chromatographic separation of the oil fraction, and properties and structure of the oil components
Authors: Boyd M L , Montgomery D S
Published: March 2018

The oil component which constituted 33.1 percent of the Abasand bitumen was resolved into a series of fractions by elution chromatography on silica gel. The saturated fraction was further resolved on activated carbon, and the most aromatic portion on both
activated carbon and alumina. The following properties were determined for most of the fractions thus prepared: elementary analysis, molecular weight, density (20°C), refractive index (nU), dispersion, the aniline point, the ultraviolet spectrum and the infrared spectrum. Quantitative estimates
of the number of methyl, methylene and aromatic carbon atoms have been made from the infrared spectra. The major fractions were then characterized by the application of three groups of structural analysis methods: (1) a representative group of methods designed for lubricating oils, (2) densimetric
methods of van Krevelen, and (3) a method developed by the authors. It was possible to separate out about one-third of the oil component as totally saturated material. The remainder of the material was separated into a series of fractions which contained increasing proportions of aromatic carbon
atoms up to about 35 percent. On the average, the oil fractions would appear to contain three rings per molecule.
Infra-red absorption by colouring matter in natural waters
Authors: Ungar J
Published: March 2018

A type of ion exchange chromatography was employed to extract organic colouring matter from natural waters. Infra-red spectroscopy of the extracts in KBr discs showed them to be markedly similar to organic matter studied by other workers using different
extraction procedures. Such groups as hydroxyl, C=C, C=0, carboxyl and CH were present. Further studies using the described extraction technique as well as the direct measurement of infra-red spectra of aqueous direct solutions are recommended.
The galvanizing behaviour of commercial steel sheet materials
Authors: Sebisty J J , Palmer R H
Published: March 2018

A statistically designed investigation has been made of the hot-dip galvanizing characteristics and behaviour of several commercially produced steel sheet materials, comprising a series of low-carbon mild steels and a representative group of low-alloy
high-strength steels. Both continuous strip and general galvanizing practice were considered in selection of the laboratory galvanizing conditions. Coating formation on the mild steels in aluminum-free zinc baths was largely influenced by the physical roughness of the steel surface, whereas in baths
alloyed with aluminum and under conditions approximating to continuous strip practice effective inhibition of the iron-zinc reaction was more dependent on the inherent chemical activity of the steel surface. As this increased, the beneficial effect of aluminum was lessened and especially so in the
case of heavily-worked mild steel sheet. The galvanizing response of low-alloy high-strength type steels in aluminum-free baths varied according to steel composition. High-silicon materials showed an extremely aggressive, linear rate of attack with time which was reflected in the formation of very
thick coatings having an unsatisfactory surface appearance. In aluminum-alloyed baths, suppression of zinc attack of the alloy steels was somewhat less effective than with mild steels, except under certain conditions where the effect of aluminum was enhanced with the high-silicon type steels.
Coatings on the latter were prone to the development of bare or uncoated spots when the aluminum concentration in the bath was high. Tensile properties of the alloy steels were affected in varying degrees by galvanizing and most significantly in the case of yield strength.
Kinetics of the reaction of niobium pentachloride with water vapor
Authors: Ingraham T R , Whalley J P
Published: March 2018

When niobium pentachloride is exposed to moist air, hydrogen chloride is liberated and hydrated niobium pentoxide or niobic acid remains. It is believed that the rate of the reaction k controlled by the rate of diffusion of water across a layer of unidentified
intermediate product of constant thickness (about 0.2 mm.). The constant thickness of the layer is maintained by the spalling and cracking of the product after it exceeds a critical thickness. Since the reaction takes place at an interface between the niobium pentuchloride and the layer of
intermediate, it is necessary to normalize the results for the decrease in inter. facial area as the reaction proceeds. When ibis is done, the rate of the reaction, expressed in terms of grams of niobium pentachloride reacting per square centimetre of interface per hour, is: Rate --- (7.7 ±
0.4) X 10 1 (p,/p) exp [( 8.1 ± 0.6) X 101/RT
Hot-dip galvanizing with less common bath additions
Authors: Sebisty J J , Palmer R H
Published: March 2018

Galvanized coating formation in "aluminum-free" and "aluminum-containing" baths otherwise alloyed with individual additions of elements not normally encountered in commercial galvanizing practice, has been investigated. It was revealed that a majority of the
fifteen elements studied were retained without difficulty in the experimental baths, although in some cases this involved intermetallic compound formation at higher concentrations of the additions. The remainder, which included some chemically reactive elements, were unstable in the bath because of
oxidation, drossing and segregation phenomena. None of the elements investigated gave indications of commercial promise when combined with aluminum and lead at concentrations applicable to continuous strip galvanizing practice. Coating formation was generally unaffected by small additions, whereas
higher levels were detrimental for various reasons, including neutralization of the inhibition of the iron-zinc reaction normally provided by aluminum at short immersion times. In nominally "aluminum-free" baths, several of the alloying elements contributed to modification of the experimental
coatings, principally by influencing iron-zinc alloy growth. For example, silver showed a pronounced accelerating effect, while significant suppression resulted with additions of chromium, manganese, nickel, titanium, and vanadium. Zirconium and silicon were also instrumental in altering the
iron-zinc alloy structure, and zinc drag-out and/or drainage were directly affected by the mechanism involved.
A thorium intermediate member of the britholite-apatite series physical and chemical studies
Authors: Hughson M R , Sen Gupta J G
Published: March 2018

In 195-1 J. P. Girault identified as britholite an occurrence of a thorium-bearing cerian silicate apatite mineral from Oka, Quebec. The unique composition of the Oka mineral, distinguished by P2O5 > SiO2 in contrast to other analyses of britholite
where silica greatly exceeds phosphorus pentoxide, suggests that the Oka mineral is an intermediate member of a series front britholite to apatite. The values of the physical properties of the Oka mineral approximate the average of those for britholite and apatite and lend support to this theory. An
appreciable amount of thorium oxide, 5.62 per cent, is present in the Oka mineral. Britholite was originally found in the Julianehaab district of South Greenland. Recently several occurrences in the U.S.S.R. have been described. The Oka mineral is clove brown, massive, and has a dull resinous
luster. The measured specific gravity of a concentrate of this mineral is 3.86 and the calculated value is 3.95. The higher index of refracton w is 1.72. The Oka mineral is hexagonal with a=9.48 A and c=6.96 A (ignited material). The possible space groups are P6,1 or / 16. An accurate ion exchange
separation technique was developed by using Dowex 50W-X8 cation exchange rcsin (50-1(X) mesh) and was applied to the quantitative separation of rare earths from phosphates, common elements and thorium all of which are present in the Oka mineral. The physical and chemical data thus obtained indicate
that the probable formula is: (Ca, re etc., Th. Mg. Fe , Na, Ti)[( P. Si. .11)(03(011, 1') which is similar to the theoretical formula proposed by Machatschki in 1939 for britholite.
A study of the constitution of the titanium-rich corner of the titanium-aluminum-molybdenum system
Authors: Williams A J
Published: March 2018

The constitution of the titanium-rich corner of the titanium-aluminum-molybdenum system, based on a four-hour annealing time, has been investigated. Vacuum heat-treatment and metallography have been used to determine the I3-transus on nine constant titanium
sections of till's system in the composition range of 0-25 1.vt % molybdenum and 0-15 wt % aluminum. Using these sections, together with published data on the titanium-aluminum and titanium-molybdenum binary diagrams, isothermal sections at 850, 900, 950 and 990°C (1562, 1652, 1742 and
1814°F) have been developed and tie-lines have been determined for these sections. Four discontinuities in the B-transus surface have been discovered. These discontinuities appear to indicate the presence of four three-phase fields which are contiguous with two-phase fields in the
titanium-aluminum binary diagram discovered by several other workers.
Surface tension of molten zinc and some zinc alloys
Authors: White D W G
Published: March 2018

The surface tension of zinc and of some zinc alloys has been determined by the sessile drop method in a program of work emphasizing detailed experimental care. From experiments carried out in a closed, isothermal cell, the temperature coefficient of the surface
tension of pure zinc over a range of temperature from the melting point (419.6°C) to 540°C was found not to be negative but to be positive. However, it was shown that by deliberately inducing continuous vapourization, a temperature coefficient of surface tension with a negative slope can
be produced. In the alloy program, the effects of aluminum, copper, lead and tin on the surface tension of 99.999+% Zn have been determined.
Corrosion fatigue of structural metals in mine shaft waters
Authors: Biefer G J
Published: March 2018

Fatigue and corrosion fatigue measurements were carried out on five commercially available metals - four steels and an aluminum alloy - which are used as structural materials in mine shaft conveyances. In the corrosion fatigue measurements, drain waters collected
in the shafts of three different Canadian mines were used as corrodents. The mine waters had been selected on the basis of their relatively large differences in acidity and/or composition. It was found that the corrosion fatigue strengths of the four steels were similar despite their differences in
tensile properties. The type of water used in the tests had little or no effect on the results. However, mild steel showed the highest and most consistent values of the damage ratio (ratio between the corrosion fatigue and the plain fatigue strengths at 10 cycles). The corrosion fatigue behaviour of
the aluminum alloy (ASTM Type 6061-T6) was found to differ markedly in the three mine waters. A high damage ratio was shown in a mine water in which the corrosion rate was low and the attack uniform. Much lower damage ratios were shown in mine waters which produced localized corrosion
attack.
Pillar loading part i: literature survey and new hypothesis
Authors: Coates D F
Published: March 2018

This research work on pillar loading is in what might be described as the area of engineering theory. As such, it is concerned largely with the combining of existing scientific theories into a rational hypothesis for predicting the loading of pillars. Hitherto,
this has been possible only in a very crude way and only for horizontal workings using the tributary area theory. In previous work on this subject, some workers have recognized that rock is not a fluid material applying a dead weight to pillars but, rather there will be a structural reaction of the
wall rock on the excavation of the vein rock. However, no complete analysis of the mechanics of the system in producing pillar loading had been established. The first step in this research work, therefore, has been to analyse the structural aspects of the problem by solving the statically
indeterminate net deflection of the walls. This net deflection at the pillars will be a measure of the increase in pillar stress resulting from mining. The resulting equations show that not only is the extraction ratio important in determining pillar loading but that the hitherto ignored parameters
of the ratio of field stress components normal and transverse to the mining zone, the height of the pillar, the location of the pillar within the mining zone, the ratio of compressibility of pillar rock to wall rock, the number of pillars across a typical section of the mining zone, the breadth of
the pillar, and the ratio of the depth from the ground surface to the span of the mining zone are all of some significance. Additional analytical work has been done in examining the various alternatives to the hypothesis that is based on elastic ground. In this work it is shown that for compatible
strain the loading of pillars will almost always be a phenomenon associated with elastic, or at least pre-failure, deformation in the walls. Consequently, any mechanisms based on post-failure rock properties will not be applicable to this problem, although they may be for other types of support. In
this supplementary work, an elliptical arching theory has been developed that may be more valid than the various other theories hitherto available for this case of loading of yielding support.
Is there difference between men and women motorcyclists?
Authors: Borstlap Hanneri , Saayman Melville
Published: March 2018

Orientation: To broaden the literature, identify markets and determine the motives of these markets within South AfricaResearch purpose: The aim was to compare male and female motorcyclists’ socio-demographic and behavioural characteristics at a motorcycle festival in South Africa.Motivation of the study: There has been an increase in motorcycle sales and events and therefore motorcycle tourism, especially in South Africa. While from an international perspective, the socio-demographic and behavioural aspects of motorcyclists are well documented, what is lacking is literature on the behavioural aspects of motorcyclists and the differences between men and women.Research design, approach and method: The study was descriptive, and data were primarily collected through self-administered questionnaires. Independent t-tests and cross-tabulation analyses were used.Main findings: Four key motives were identified for attending the South Africa Bike Festival. The findings also confirmed that male and female motorcyclists differ from both socio-demographic and behavioural aspects and should be viewed as two distinctive segments. In addition, the research confirmed the importance of the age at which motorcyclists were exposed to motorcycling.Practical managerial implications: Marketing campaigns should focus on both segments and should appeal to all motivational factors that have been identified.Contribution: The study contributes to the motorcycle literature and provides a greater understanding of motorcyclists’ behaviour and what motivates them to attend a motorcycle festival. The research provides guidelines to event organisers to effectively market such an event. The research also identifies different segments to this event, which provides more indications on what the motorcyclist looks like.
Investigating selected self-management competencies of managers
Authors: Steyn Zandri , Van Staden Louis J.
Published: March 2018

Orientation: Self-management serves as an essential managerial competency and entails taking responsibility for one’s own actions and behaviour. The problem is that managers who do not have effective self-management competencies may affect business adversely.Research purpose: The study investigated selected self-management competencies of managers within the manufacturing industry of South Africa.Motivation for the study: The researchers wanted to focus on selected self-management competencies of managers rather than all the managerial competencies.Research design, approach and method: A quantitative research method was employed by following a descriptive design and data were obtained using a well-structured self-administered questionnaire.Main finding: The results revealed that a significant and positive relation exists between managers’ integrity and ethical conduct, and between personal drive and resilience, as well as a significant positive relationship between work–life balance on the one hand and self-awareness and self-development on the other – all of which are components of their self-management competency.Practical/managerial implications: For managers to contribute to the success of a business, it is essential that they succeed in applying self-management competencies to distinguish them from their competitors.Contribution/value-add: No previous studies could be found investigating the relationship between integrity and ethical conduct, and between personal drive and resilience, as well as between work–life balance on the one hand and self-awareness and self-development on the other.
Comparative evaluation of salivary malondialdehyde levels as a marker of lipid peroxidation in early childhood caries
Authors: Subramanyam Divya , Gurunathan Deepa , Gaayathri R. , Vishnu Priya V.
Published: March 2018

Objective: The aim of this study was to evaluate the association between lipid peroxidation and dental caries in children with ECC by estimating the levels of MDA in saliva of children. Materials and Methods: A total of 150 children were selected; 75 children with ECC and 75 children without caries (non-ECC). Saliva samples were collected and centrifuged at 12,000 rpm for 24 min at 4°C to obtain a supernatant. MDA levels were estimated by Buege and Aust method by using thiobarbituric acid. The data obtained were analyzed by Student’s t-test to compare MDA levels between the groups. Results: MDA levels were higher in children with ECC. There was no statistically significant difference between children with ECC and without ECC (non-ECC). Conclusion: MDA levels were slightly higher in children with ECC, indicating the role of lipid peroxidation in the carious process.
Cone-beam computed tomography in the assessment of periapical lesions in endodontically treated teeth
Authors: Gambarini Gianluca , Piasecki Lucila , Miccoli Gabriele , Gaimari Gianfranco , Nardo Dario Di , Testarelli Luca
Published: March 2018

Objective: This study aimed to evaluate the relationship between the quality of the coronal restoration and the root canal filling on the periapical status of endodontically treated teeth using CBCT. Materials and Methods: CBCT data were obtained from the records of patients who deny any dental treatment in the 2 years prior to the CBCT examination. CBCT images (90 kVp and 7 mA, exposure time of 23 s, and a voxel size of 0.2 mm, with a field of view of 13 cm x 13 cm) of 1011 endodontically treated teeth were observed. A score was given to the quality of the root filling and the quality of the coronal restoration. Statistical Analysis Used: Data were statistically analyzed to correlate the periapical status with gender, dental group. and quality of endodontic treatment and restoration (Chi-square test with a significance level of P < 0.001). Results: Absence of periapical periodontitis was found in 54.9% of the cases. The periapical outcome was not related to gender or dental group (P > 0.05). A statistically significant factor (Chi-square test, P < 0.0001) resulted when different qualities of sealing were compared. Conclusions: CBCT showed that high-quality root canal treatments followed by an adequate coronal sealing restoration avoid the presence of periapical periodontitis in time.
Gingival melanin depigmentation by 810 nm diode laser
Authors: Elemek Eser
Published: March 2018

The color of gingiva is determined by number and size of blood vessels, thickness of epithelium, keratinization degree, and melanin pigments present in epithelium. Melanocytes, located in basal and suprabasal layers of epithelium, are the cells that produce melanin pigments which play a main role for pigmentation of gingiva. In this case series, the use of 810 nm diode laser for depigmentation of gingiva is presented. Two female patients applied with a chief complaint of “darkened gums” due to heavy smoking. In intraoral examination, diffuse melanin pigmentation was observed in both the maxilla and mandible. Under the local anesthesia, 810 nm diode laser was applied for depigmentation at 1.3 W power in continuous mode. Patients were recalled at weeks 1, 4, and 12 to evaluate the healing and recurrence rate. Both the patients had no postoperative pain or edema, and complete healing was observed at week 12. This study revealed that depigmentation with 810 nm diode laser is successful in terms of esthetics and patient comfort.
Multiplicative stochastic heat equations on the whole space
Authors: Hairer Martin , Labbé Cyril
Published: March 2018

We carry out the construction of some ill-posed multiplicative stochastic heat equations on unbounded domains. The two main equations our result covers are the parabolic Anderson model on

\mathbb R^3

, and the KPZ equation on

\mathbb R

via the Cole–Hopf transform. To perform these constructions, we adapt the theory of regularity structures to the setting of weighted Besov spaces. One particular feature of our construction is that it allows one to start both equations from a Dirac mass at the initial time.
Peste porcine chronique : propriétés in vitro et in vivo de 7 souches de virus isolées dans des élevages présentant des troubles de la reproduction
Authors: Aynaud Jean-Marie , Corthier G. , Laude H. , Vannier Philippe , Tillon J. P.
Published: March 2018

Seven virus strains have been inoculated in experimental conditions by intra¬ muscular or by genital route : 1) To 3 days old piglets ; 2) To 50 days old piglets ; 3) To sows, at the time of service (semen-virus mixture) or at the 30 th day of pregnancy. Results shown : 1) These strains are attenuated for piglets and sows but seem to be virulent for embryos or foetuses ; 2) The genital tractus is susceptible to viral infection ; 3) The virus strains are characterized by a weak immunogenic activity (low level of neutralizing antibody in the serum) ; 4) The age of animal seems to be the most determinant factor for expression of virulence and immunogenic activity ; 5) These low virulent strains have in vitro and in vivo properties which are intermediate between those of virulent strains and those of lapinized strains.
Shallow architecture of Fuegian Andes lineaments based on Electrical Resistivity Tomography (ERT). Evidences of transverse extensional faulting in the central Beagle Channel area
Authors: Bran Donaldo Mauricio , Tassone Alejandro Alberto , Menichetti Marco , Cerredo María Elena , Lozano Jorge Gabriel , Lodolo Emanuele , Vilas Juan Francisco
Published: March 2018

The southern foothills of the Fuegian Andes are bounded by the Beagle Channel (BC), a conspicuous E-W longitudinal basin, controlled by a large transcurrent fault system, which extends from the Atlantic to the Pacific Ocean. The northern shore of the Beagle Channel’s central segment is characterized by several E-W oriented valleys, parallel to the main basin, which are interspersed with a series of oblique NW trending lineaments that extend across the mountain belt. A geoelectrical survey was carried out in order to investigate the shallow architecture of such sets of linear morphologies. The principal E-W lineament system was characterized by conspicuous sub-vertical resistivity contrasts, interpreted as fractured zones associated with fault strands of the main strike-slip Beagle Channel system, whereas the oblique NW-SE trending set of lineaments revealed slightly different resistivity patterns, with vertical displacements and less abrupt contrasts. These resistivity patterns, in combination with the widespread occurrence of normal faulting in the area, allowed to infer an extensional control over the oblique depressions. These morphological features were related to oblique transverse faults that segment two sub parallel E-W fault systems. The oblique faults were probably developed along inherited structural anisotropies and can be extended well beyond the BC shoreline to the NW. Both geophysical and field evidence suggest a post-glacial deformation along the area.
Neogene-Quaternary seismic stratigraphy of the Llancanelo Lake Basin, Mendoza, Argentina
Authors: Onnis Luciano , Violante Roberto Antonio , Osella Ana , De la Vega Matías , Tassone Alejandro , López Ernesto
Published: March 2018

A new shallow multichannel seismic survey was carried out in the Llancanelo Lake region (Southern Mendoza Province, Argentina), in order to complete and extend previously surveyed seismic sections. The new seismic data allowed to double the already existing data. The obtained information was correlated with seismic and stratigraphic data from the industry. In this way it was possible to depict the major Neogene-Quaternary sedimentary-volcanic sequences and the regional evolution of a tectonic-volcanic basin located in a key region at the eastern foot of the Andes cordillera. This research is settled on early studies that comprised seismic works reaching depths of 600-700 m as well as geoelectric and electromagnetic surveys reaching the uppermost 80-100 m of the sequences. The obtained results indicate the presence of three major sedimentary units separated by conspicuous seismic horizons SR1, SR2 and SR3, respectively considered as representing the late Mesozoic transition from marine to continental deposition, the beginning of the Cenozoic basaltic volcanism, and the change from dominantly sedimentary to dominantly volcanic processes at the base of the Quaternary. The resulting stratigraphic scheme reveals increasing volcanic (basaltic layers) intercalations with depth that accommodate to the geometry of the depocenter.