bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer programs for x-ray crystallography part i. bond and angle scan program
Authors: Gabe E J
Published: March 2018

This program, which is the first in the series, is designed to facilitate the interpretation of the results of crystal structure analysis. Using the unit cell data, the fractional atomic coordinates and the symmetry operations, the program finds the coordination,
in terms of distances and angles, around a specified group of atoms of interest. The program will handle all types of symmetry and there are essentially no limits on the size of structure that can be dealt with, other than the size of the memory of the computer.
The analysis of stress for the prediction of crater boundaries
Authors: Sassa K , Laroque G E , Coates D F , Darling J A
Published: March 2018

A method of analysis is developed to compute the stress distribution resulting from detonation of a contained spherical charge in an elastic medium in the vicinity of a free face. This analysis uses the dynamic elastic properties of the medium, and the direct
dilatational displacement and particle velocity wave shapes produced by the explosive, as a function of distance. Principal stresses at a point, as a function of time, are computed by superposition of the stress components due to the direct dilatational wave and the reflected dilatational and shear
waves, using plane wave reflection theory. A computer program has been written to perform this analysis. Laboratory and field measurements were used to obtain the necessary data to determine stress distribution and to predict crater dimensions. In the field experiments, a direct dilatational wave
linear array and a shear wave linear array were used to determine all displacements and particle -velocity wave shape data, as well as the dilatational wave velocity and shear wave velocity. It was found that only moderate changes occurred in displacement and particle velocity wave shape with
distance. Both displacement and particle velocity decayed with distance according to a power law relationship in the range considered.Two explosives were used in the field program. It was found that the ratio of the detonation pressures of these two explosives, corrected to the ratio of the imposed
pressure of these two explosives by means of an acoustical coupling relationship, were in agreement with the ratio of the peak radial stress as determined in the computer program for the two explosives at equal distances from a shot centre. Some agreement was found between predicted crater
dimensions and those actually observed.
Tectonic interpretation of elastic-strain-recovery measurements at Elliot Lake, Ontario
Authors: Bielenstein H E , Eisbacher G H
Published: March 2018

Bedding-plane slip, contraction faults, slickensided fractures, matrix-clast displacements, quartz veins, joints, and regional folds and faults were analysed in detail near Elliot Lake, Ontario, to test the potential of this approach for predicting the
orientation of in-situ stresses in rock masses. The major principal compressive stresses during deformation of the region were oriented subhorizontally and south-southeasterly. Gradual stress release by slow regional arching during the last 1000 million years is expressed in post-tectonic quartz
veins and joints which have predominantly easterly trends. Measurements of in-situ state-of-stress by overcoring in vertical upholes indicate a boundary between stresses due to mining and field stresses unaffected by mining: about 3 to 6 metres above the mine roof, maximum elastic strain recovery
changes from a north-south to an east-west direction. In-situ elastic strain recovery within the field stress environment is greatest parallel to the trend of late quartz veins and joint sets. Field stresses, therefore, are interpreted as remnants of former regional tectonic
stresses.
Continuous automatic cyanide titration in copper-bearing gold mill leach liquors
Authors: Ingles J C
Published: March 2018

This report describes the preparation and evaluation of a new silver-complex reagent formulation for the continuous titration of cyanide in cupriferous gold-leaching solutions. Some improvements in the design of the continuous automatic titrating apparatus are
also described, and the significance of the "free" cyanide value in the control of the cyanide gold-leaching process is discussed.
The leaching of manganese from pyrolusite ore by pyrite
Authors: Thomas G , Whalley B J P
Published: March 2018

A new method of leaching low-grade manganese ore (< 5% Mn) utilizing pyrite as a reagent was developed. By heating an aerated slurry of ore and pyrite and by recycling the leach liquor at controlled acidity to attack fresh ore, a manganous sulphate
solution free of iron was obtained which when heated to about 175°C., yielded manganous sulphate monohydrate. During the leaching process, iron in the liquor was alternately oxidized by the pyrolusite and reduced by the pyrite. In an alternative leaching procedure, the heating of an aqueous
slurry of pyrite in an autoclave first under oxygen pressure and then in the absence of oxygen produced an acidic ferrous sulphate solution suitable for the subsequent leaching of pyrolusite ore at ambient temperatures
The compound CaO. Ti2O3
Authors: Bright N F H , Rowland J F , Wurn J G
Published: March 2018

By electrolyzing baths of molten CaCl 2 containing perovskite(CaO.Ti0 2 ), a compound within the ternary CaTi-0 system, namely CaO.Ti203, has been obtained. The compound has been identified by chemical analysis, and its crystallographic data have been determined
by X-ray means. Attempts to synthesize the compound apart from the electrolytic cell have, so far, failed.
The influence of aluminum, lead and iron on the structure and properties of galvanized coatings
Authors: Sebisty J J , Edwards J O
Published: March 2018

This report describes the preliminary phase of a statistical study on the influence of aluminium and lead additions in iron-saturated baths on the structure and properties of galvanized coatings prepared by the dry galvanizing technique. Different levels of
aluminium and lead, and ranges of bath temperature and immersion time were investigated using two grades of steel sheet. It was found that the immersion time and aluminium content of the bath had the most significant effect on such factors as coating weight, steel weight loss, iron content and alloy
growth in the coating, and ductility and adherence of the coating. The bath temperature was also significant but to a lesser degree. The lead content of the bath was the most significant variable affecting coating surface appearance. For immersion times up to 2 minutes, attack of the steel base was
largely blanked-off by an addition of 0.2 per cent aluminium. With 0. 1 per cent aluminium, vigorous steel attack and continuous iron -zinc alloy growth was apparent even for short immersion times. Accelerated corrosion tests suggested that aluminium and to a lesser degree lead had a significant
effect in promoting "white rusting" of the galvanized coatings.
Some new fluoride complexes of trivalent titanium
Authors: Bright N F H , Wurn J G
Published: March 2018

Three new complex fluorides of trivalent titanium have been isolated from the products of electrolysis, under an inert atmosphere, of molten baths of I<C1, NaC:I, or mixtures of KC1 and .Na.CI, containing either K2TiF6 or Na2TiFe . Electrolytic baths
containing a mixture of IN:CI and NaCl with either 1: 2TiF 6 or Na2TiF yielded a violet-colored, face-centered cubic compound identified as K 2NaTiF6 , which was virtually insoluble in water and amenable to electrostatic separation from the metallic titanium also produced in the electrolysis. Baths
containing molten mixtures of K2TiF 6 and ECI gave a pale violet compound K3TiF 6 , which was slightly soluble in water. Baths containing Na2TiF6 and NaCI gave a deep violet-colored compound Na3TiF6 which was almost insoluble in water. The compounds Kv3TiF 6 and NalTiF6 have structures which
approximate to cubic. The compounds K2Na1'i12 6 and Na3TiF6 are more stable to atmospheric oxidation than is N3TiF6. X-Ray diffraction patterns have been recorded for these compounds and some of their physical and chemical properties determined.
Properties of sand-cast magnesium alloys
Authors: Lagowski B , Meier J W
Published: March 2018

The magnesium-zinc alloy system is today the most important base for high-strength magnesium alloys. Unfortunately, published data on properties of binary Mg-Zn casting alloys are both limited and controversial. It was, therefore, necessary to undertake a
systematic study of the effect of composition and various melt treatments on the foundry characteristics, amenability to heat treatment, mechanical properties, and metallographic structure of this alloy series. Work on grain refinement of magnesium-zinc alloys included superheating, carbon
inoculation, and additions of small amounts of aluminum, iron, manganese, titanium and zirconium. Results of the investigation show the necessity for considerable revision of long accepted data.
A radioactive dial marker for the Decca Navigational Aid
Authors: Alexander G E , Eichholz G G
Published: March 2018

A small auxiliary unit has been designed for use in conjunction with a Decca Navigational System on survey flights. The unit is intended to trigger a relay system which actuates an aerial camera every time the dial pointer on the Decca dial passes through zero.
For this purpose, the pointer tip has been coated with radioactive caesium-137 whose activity is detected by a Geiger tube located above the dial face. Details are given of the mechanical arrangement and of the design of the circuit which is fully transistorized.
Isolation of the rare earth elements
Authors: Zimmerman B J , Ingles J C
Published: March 2018

A total chlorination treatment of radioactive ores and concentrates, with simultaneous volatilization at 900 ° C., eliminates most of the non-rare earth elements, including thorium and scandium. A subsequent ammonia precipitation removes the alkalies and
alkaline earths and isolates the rare earths, including yttrium, in a pure concentrate suitable for weighing, spectrographic examination, or calorimetric determination. With materials consisting primarily of uranium and thorium compounds, preliminary extraction from nitric acid medium with a carbon
tetrachloride solution of tributyl phosphate eliminates the bulk of these elements, permitting use of a larger sample and thus extending the range of the method. Over-all recoveries of the rare earth elements are 90% or better.
Properties of sand-cast magnesium alloys part IV: Mg-Ag, Mg-Ag-Zr and Mg-Ag-Zn-Zr Alloys
Authors: Lagowski B , Meier J W
Published: March 2018

The long-term research program on high-strength magnesium alloys, being conducted since 1945 at the laboratories of the Physical Metallurgy Division, Mines Branch, Department of Mines and Technical Surveys, Ottawa, has included a study of binary and more complex
alloys based on the magnesium-silver system. The results of the investigation related to sandcast Mg-Ag, Mg-Ag-Zr and Mg-Ag-Zn-Zr alloys are presented and show that all three of these alloy groups have good ductility and are amenable to solution strengthening. Precipitation-hardening, to any
appreciable extent, was found only in certain alloys of the Mg-Ag-Zn- Zr system. Some of these alloys show exceptionally high yield strength.
Measurement of dissolved air in alkaline solutions from uranium mills and from gold mills
Authors: Thomas G , Ingraham T R
Published: March 2018

A simple and rapid method has been developed for determining the relative saturation of air in the alkaline solutions used in processing uranium ores and gold ores. The method is based on the diffusion current produced by oxygen from the dissolved air when a
sample of the solution is subjected to a controlled potential applied to a calomel anode and a platinum cathode. Since the diffusion current is proportional to the relative saturation of air in the solution, and since only relative saturation levels are required for mill control work, it is
sufficient to apply a fixed potential and to measure the diffusion currents with a microammeter
The development of an improved steel for the production of propulsion shafting for naval vessels part i: an examination of steel currently in use part ii: modifications of this steel
Authors: McDonald R D , Morgan W A
Published: March 2018

This report covers an investigation of properties obtainable in material currently in use for the production of propulsion shafting for naval vessels, and of the possible improvements attainable by increased manganese/carbon ratios and with low alloy additions.
The initial purpose of the program was the improvement of impact properties without sacrificing other mechanical properties attainable in the currently used material. The results indicate that a very considerable improvement is obtainable, with accompanying improvements in tensile and fatigue
strength and without any appreciable increase-in fatigue notch sensitivity when subjected to rotational bending fatigue stresses.
Decomposition pressures of ferric sulphate and aluminum sulphate
Authors: Warner N A , Ingraham T R
Published: March 2018

The gas pressures over samples of anhydrous ferric sulphate and anhydrous aluminum sulphate have been measured in a static system, using a mercury manometer in which the exposed surface was covered with a flexible Pyrex bellows. The calculated MI for the
decomposition of Fe2(SO4 ) 3 was +135.4 kcal/mole. It was not possible to calculate the A H for the Al 2(SO4 ) 3 decomposition, because a discrete aluminum oxide with singular thermodynamic properties was not obtained. In the Fe2(SO4 ) 3 system, the fraction of SO3 in the-gas phase was found to be
almost constant over the range of temperature and pressure changes used in the study. At any given temperature, the decomposition pressure over a ferric sulphate sample is greater than that over an aluminum sulphate sample, thus indicating that preferential decomposition of ferric sulphate should be
thermodynamically feasible in mixtures of ferric sulphate and aluminum sulphate.
The system iron-titaniumoxygen at 1200°c and oxygen partial pressures between 1 atm. and 2 x 10-14 atm
Authors: Webster A H , Bright N F H
Published: March 2018

The 1200°C. isotherm in the system Fe-Ti-O has been studied by equilibrating mixtures of iron oxide (Fe202) and titanium oxide (TiO2) with atmospheres of controlled oxygen partial pressure. These atmospheres consisted of CO2, air, oxygen, mixtures of CO2 and
11 2, and mixtures of CO2 and CO. The resulting oxide mixtures were examined at room temperature by chemical analysis and by X-ray diffraction. The stability regions of the a-oxides (Fe,Ti2,03), of the spinets, (FeTi 2,0,), and of the orthorhombic oxides (Fe Ti 3O5) were determined. Some
nonstoichiometry occurs in the spinels and in the a-oxides. The oxygen partial pressures at which spinel is reduced to (iron + a-oxides) and at which a-oxide (ilmenite) is reduced to (iron -I- orthorhombic oxide) were determined as 2.1 X 10-' 3 and-9.3 X 10 -' 4 atm., respectively. The orthorhombic
solid solution series extends over the whole range of oxygen partial pressures studied.
Electrode potentials of the uranium chlorides in fused alkali chloride solutions
Authors: Flengas S N
Published: March 2018

Using a silver - silver chloride reference electrode, the electrode potentials of the system U, UCI3(KCI, NaC1) and the redox potentials of the system Pt, UCI3, UC1 4(KC1, NaC1) were measured at various concentrations of the uranium chlorides and at temperatures
between 650 and 850° C. From the results, the electrode potential of the system U, UC14(KCI, NaCI) was calculated. In addition, the activity coefficients and partial molal properties of dilute solutions of UC13 and UCI4 in the equimolar mixture of potassium and sodium chlorides were
calculated.
The determination of methyl and methylene groups in the oil and resin fractions of Athabasca bitumen using infrared spectroscopy
Authors: Goodspeed F E , Montgomery D S
Published: March 2018

A method of determining the methyl and methylene carbon present in the oil and resin fractions from the Athabasca bitumen, using infrared absorption spectra, has been developed. Absorption bands in the 3- and 7-micron regions are used, and data on pure compounds
serve as a basis for quantitative estimates of these groups. Estimates obtained for the oil fractions were supported by the agreement of the total hydrogen content of the fraction from the ultimate analysis with the hydrogen content predicted by this method.
I. The binary system Nb2O5 -SiO2 ; II. The binary system CaO-Nb2O5
Authors: Ibrahim M , Bright N F H , Rowland J F
Published: March 2018

The binary system Nb205--S102 has been shown to include an extensive two-liquid region over the range 5 to 80% Nb205. The minimum temperature of the two-liquid area is 1695°C. A eutectic composition occurs at 95% Nb205 and 1448°C. and another at
approximately 5% Nb2O5 and 1695°C. The experimental results were obtained by the cone-fusion method. : The binary system CaO-Nb205 has been shown to include three compounds: CaO -Nb2Or which melts congruently at 1560°C; 2Ca0 -Nb20s, which melts congruently at 1576°C; and 3Ca0-
Nb20s, which melts incongruently at 1560°C. Three eutectic compositions occur at 6% CaO (1362°C), 23 ( ; CaO (1492°C), and 34% CaO (1535°C). These results were obtained by the cone-fusion technique. The compound 3CaONb205 has been shown to exist in two forms : type I,
face-centered cubic with a = 7.978 A, having a superlattice with a = 23.934 A, and type II, orthorhombic (pseudotetragonal, distorted cubic) with a = 11.51 A, b = 11.10 A, r = 15.98 A, having a pseudocell with a = 5.754 A, = 5.551 A, and c = 7.990 A. The conditions controlling the formation of these
two forms were not determinable from the experiments conducted.
The effect of some test bar variables on the mechanical properties of aluminum alloys
Authors: Couture A , Meier J W
Published: March 2018

The effect of machining on the tensile properties of aluminum alloy test bars was investigated. Although certain of the differences in ultimate strength and elongation were found to be statistically significant in some cases, they were of the same- order as
differences that are observed between melts of the same composition. A comparison of 0.1% and 0.2% yield strength values, obtained on test bars of various aluminum alloys, showed that the linear relationship between these two values is different for most of the alloys investigated.
Similarly, linear relationships between the elongation values used in North America (4D) and in Great Britain (3.5D) were found for the alloys investigated.
The composition and crystallography of niocalite
Authors: Nickel E H , Rowland J F , Maxwell J A
Published: March 2018

Niocalite is monoclinic with a = 10.83, b = 10.42, c 7.38 A, and = 109°40'. On the basis of two chemical analyses, the generalized formula is (Ca, Nb)ieSi8(0, OH, F)36. 'The similarity of niocalite to woehlerite, hiortdahlite, and låvenite is
discussed.
The composition and microtexture of an ulvöispinel magnetite intergrowth
Authors: Nickel E H
Published: March 2018

Chemical analysis, x-ray diffraction, and electron microscopy , have been used to determine the composition and microtexture of an ulvöspinel-magnetite intergrowth in titaniferous iron ore from Rouville County, Quebec. The composition of the ulvöspinel
is estimated to be (Mgn. 42Fen ) (Fe1.01Tio.71A10. 26 )0 3 .9o. It has a spinel-type structure with a 8.460 A. Electron micrographs show an exsolution texture consisting of pleonaste lamellae and magnetite cubes in an ulv6spinel matrix.
Effect on reagent consumption of recycling solutions in the weak acid leaching of a uranium ore
Authors: McNamara V M , Gow W A
Published: March 2018

An investigation was carried out to study the possibility of reducing the acid requirements in the leaching of uranium ores at controlled pH, by recycling a portion of the leach liquor as make-up solution with fresh ore. The work was carried out on a laboratory
scale on a siliceous ore. Ore fineness, and quantity of oxidizing agent (sodium chlorate) added, were the two variables investigated. Acid consumption at pH 1.8 was reduced from 44.2 pounds per ton for the standard leach without recycling to 38.7 pounds per ton with recycling when the ore was ground
to 75-80 percent minus 200 mesh, and, in the same comparison, from 37.3 pounds per ton to 29.7 pounds per ton when the ore was g_round to 40-50 percent minus 200 mesh. Recycling also permitted a reduction of the amount of sodium chlorate required, for satisfactory leaching, from 3.0 to 1.5 pounds
per ton. However, reducing the sodium chlorate reduced the amount of acid saved by recycling. Recycling had no significant effect on the amount of uranium extracted
Voltaic cells in fused salts part v. the systems SniSnCl2 (KC1-NaC1), Fe/FeC1 (KC1-NaC1), and Mn/MnC12 (KC1-NaC1)
Authors: Flengas S N , Ingraham T R
Published: March 2018

Using a Ag/AgC1 (KCI-NaCI) reference electrode, the standard electrode potentials of the systems Sn/SnC1 2 (KC1-NaCI), Fe/FeC12 (KCI-NaCI), and Mn/IInC1 2 (KCI-NaC1) were determined at 700° C and found to be 0.370 v, 0.520 1.7, and 1.205 v respectively. In
each of the systems the Nernst equation was found to be applicable over the range of concentrations investigated. The effect of temperature on the electromotive forces of the above cells was measured and the heats of the cell reactions were calculated from the data.
Competitive adsorption of C14 -labelled oleic acid by quartz and hematite in flotation processes
Authors: Lapointe C M
Published: March 2018

The adsorption of C 14 -labelled oleic acid on quartz and hematite has been studied in benzene for surface area measurements, and in water for flotation purposes. Although the results on surface areas for hematite agree with the expected values, those for quartz
are but a fraction of the values of a monolayer. Contact and flotation tests in aqueous emulsions of oleic acid showed a definite effect of even a small amount of quartz on the adsorption of oleic acid by hematite, at near-neutral pH. Improved techniques of radiometric measurements are described for
solutions, emulsions and films of oleic acid adsorbed on solids. A new method for extracting the oleic acid from water with the liquid scintillator and measuring its activity in a two-phase liquid system is described.
High-temperature behaviour of aluminous cement concretes containing different aggregates
Authors: Zoldners N G , Malhotra V M , Wilson H S
Published: March 2018

Changes in physical properties of about 400 concrete test specimens, made with aluminous cement and expanded shale, anorthosite, ilmenite and phonolite aggregates, were studied after exposure to temperatures ranging from 100 to 1100°C. It was found that the
aluminous cement concrete loses its strength rapidly in the range of temperatures investigated. Expanded shale aggregate concrete showed the greatest stability retaining about 20 per cent of its original compressive strength after firing at 1000°C, whereas concrete made with phonolite aggregate
was the least heat-resistant of the four types investigated. The fired concrete specimens were tested for strength and examined petrographically. Probable causes of reduction in strength due to exposure to elevated temperatures are discussed briefly.
Wodginite--a new tin-manganese tantalite from Wodgina, Australia, and Bernic Lake, Manitoba
Authors: Nickel E H , Rowland J F , McAdam R C
Published: March 2018

The name wodginite is proposed for a mineral round at two widely separated localities Wodgina, Australia and Bernic Lake, Manitoba. The mineral is monoclinic, space group C2/c or Cc, with cell parameters of a = 9.52 A, b = 11.47 Å, c = 5.10 Å and B = 91°18'
(Wodgina) and a = 9.47 Å, b = 11.42 Å, r = 5.09 Å and B = 91°02' (Bernie Lake). Its composition is expressed by the formula A 16032 , where A represents chiefly Ta, Sn and Mn, with lesser amounts of Nb, Fe and Ti. The relationship of wodginite to columbite-tantalite, ixiolite and olovotantalite
is discussed.
On the origin of anthraxolite and impsonite
Authors: King L H
Published: March 2018

Anthraxolites and impsonites are of secondary origin, but it is difficult to ascertain their point of entry in the secondary development track. They are normally described as being homogeneous and structureless; however, six of the twelve samples examined during
this study possess a fine crystalline structure. The presence of crystalline material provides a basis for further speculation on their origin, as the conditions for crystallization in organic materials limit the various possibilities. It is thought that the material must have been quite aromatic in
composition during deposition and that it probably migrated in an aqueous environment. It is also suggested that the migrating fraction originated as an alteration product of primary sedimented organic matter.
Kinetic studies on the thermal decomposition of calcium carbonate
Authors: Ingraham T R , Marier P
Published: March 2018

Kinetic studies have been made of the thermal decomposition of precipitated calcium carbonate, powdered calcite, and regular fragments of calcite crystals. The powdered materials were examined in the form of pellets, which were prepared by compacting the powder
to about 70% of its theoretical density. The work was done at one atmosphere of pressure in a flow of air containing various amounts of carbon dioxide. It was observed that the decomposition of the pellets, which were prepared in a variety of shapes, was characterized by the same advancing
interface mechanism as that observed for single specimens of crystal fragments. When the rates of decomposition were normalized for the change in of interfacial area accompanying decomposition, it was possible to correlate the observed rates of decomposition for a variety of pellet shapes, and to
relate these rates, as a function of particle size and pellet roughness, to the rates of decomposition of large fragments of calcite crystals. The activation energy for the decomposition reaction was found to be 40.6 kcal/mole. At a constant temperature, the decrease in reaction rate with increasing
carbon dioxide pressure was found to be proportional to the difference between the equilibrium dissociation pressure and the back pressure of carbon dioxide. A reaction mechanism based on diffusion through a constant thickness of active calcium oxide is suggested.
The determination of lead by a solvent extraction-EDTA titration procedure
Authors: Hitchen A
Published: March 2018

A rapid, simple and precise method has been developed for the determination of 0.05 to 500 milligrams of lead, in mixtures of lead, titanium and zirconium precipitates used for the manufacture of ceramic transducers, and also in lead ores, concentrates and
minerals. Lead is determined by titration with disodium ethylenediaminetetraacetate using Xylenol Orange as indicator, after separation from interfering elements by chloroform extraction of lead diethyldithiocarbamate. Complexation with cyanide and tartrate eliminates the interfering effect of most
elements except bismuth, antimony, tin, manganese, and phosphate. The interference of all these except bismuth can be prevented by special procedures, which are described. In the case of bismuth, the method permits it to be determined along with the lead by a successive titration, and a procedure
for accomplishing this is also given.
Theory and experiment in methods for the precision measurement of surface tension
Authors: White D W G
Published: March 2018

Methods of measuring surface tension are appraised for their suitability to liquid metals at elevated temperatures. Selected methods are examined for their potential sources of error and the means are discussed for eliminating, minimizing, or correcting for
error.
The hot-tearing of copper alloys
Authors: Couture A , Edwards J O
Published: March 2018

A test and a rating method have been developed to assess the hot-tearing susceptibility of cast copper alloys. Thirteen alloys were rated, and, while the limitations of individual hot-tear tests are well known, it is considered that such a rating should serve as
a general guide to enable foundrymen to select alloys with the best hot-tear resistance where this may be important in a particular casting design. The probable process by which these alloys - particularly tin bronzes - solidify is tentatively related to the hot-tearing mechanism, which is discussed
in general terms. From this type of study, it may be possible to design alloys of improved hot-tear resistance, or to anticipate hot-tearing difficulties in new alloys designed from other considerations.
Pillar loading part ii: model studies
Authors: Coates D F
Published: March 2018

The research work on pillar loading has been concerned with the combining of existing scientific theories into a rational hypothesis for predicting the loading of pillars. With the establishment of this hypothesis empirical substantiation or modification became
required. The data from existing model work was analysed and supplementary experimental work conducted, so that the various parameters indicated by the hypothesis as being significant could be examined. Measurements of pillar stresses in laboratory models of gelatin, Araldite-type materials, mortar
and steel showed that it is possible to predict the variation of pillar loadin.g with location within the mining zone, with variation of pillar height, with variation of pillar breadth, with the number of pillars across the mining zone, with the variation of the compressibility of the pillar ground
with respect to that of the walls, with variation in the magnitude of the field stress component acting transversely to the mining zone or vein, and, above all, with the extraction ratio. However, by analysing data with respect to the various parameters it was found necessary to modify the
theoretical equations for the functions including the location of the pillar, the effect of the stress component acting transversely to the mining zone, and the effect of pillar breadth in a mining zone having pillars of unequal width. These modifications have been made following the traditional
engineering procedure of taking into account both the empirical evidence and the mechanism (if it can be recognized but has not been included in the theory) that is causing the deviation of the data from theory. The most significant parameters, aside from the extraction ratio, affecting the pillar
loading have been shown to be the ratio of compressibility of the pillar rock to wall rock, the height of the pillar, and the breadth of the pillar in mines with pillars of unequal width,
The complexometric titration of zirconium in perchloric acid solution, and its application to the analysis of lead zirconate-titanate ceramics
Authors: Hitchen A
Published: March 2018

A rapid, simple, precise and accurate method is described for the titrirnetric determination of zirconium. The sample, after a fuming with perchloric acid, is diluted with water and titrated with a standard solution of disodium ethylenediamine tetraacetate
(EDTA), using Xylenol Orange as the indicator. Except for bismuth, iron (III), tin, antimony, niobium, mercury (I), arsenate, sulphate and fluoride, relatively few ions interfere; and procedures for overcoming the interferences or eliminating the interfering ions are described. Because titanium and
lead do not interfere, this titration procedure has been successfully applied to the direct determination of zirconium in lead zirconate-lead titanate ceramic materials . A special fuming technique makes possible the "activation" of up to 205 mg of zirconium and is a major factor in obtaining the
high precision.
The thermal decomposition of pyrite
Authors: Coats A W , Bright N F H
Published: March 2018

A study has been made of the kinetics of the thermal decomposition of pyrite to pyrrhotite and sulphur in a dynamic argon atmosphere. The reaction was followed (a) by the rate of loss of weight as indicated by the extension of a quartz spring and (b) by the rate
of progression of the pyriteipyrrhotite interface into a polycrystalline compressed pellet. The temperature coefficient of the reaction was found to be 69.5 ± 5.9, 64. 7 +- 3.3 and 66.9 ± 5.1 kcal. mole- 1 when the results were processed in three different ways. The pyriteipyrrhotite
interface was found to progress at a linear rate into the pellet and equations were derived to express the variation of reaction rate with temperature. Attempts to study the early nucleation stage of the decomposition, using mineral crystals, proved abortive.
The determination of zirconium, niobium and hafnium in low alloy steels by x-ray spectrography
Authors: Reed D J
Published: March 2018

Zirconium, niobium and hafnium have been determined in mild steels by X-ray spectrography in amounts up to 0.35, 0.30 and 0.Z0% respectively with errors of less than + 0.01%. Because suitable standards for zirconium and niobium were unavailable and no
standards for hafnium existed, it was necessary to use synthetic standards. A number of samples have been set up as Mines Branch secondary standards and the validity of their use has been verified. Using accelerating potentials of 80 or 90 kV, zirconium and niobium may be determined in the ppm
range. The sensitivity for hafnium is 0.01%.
Literature review on the techniques of sonar profiling and grid sampling, using a grab sampler for the identification and mapping of lake seditment facies for environmental effects monitoring
Authors:   Aquatic Effects Technical Evaluation (AETE) Committee
Published: March 2018

A literature review on the techniques of sonar profiling and grid sampling, using a grab sampler was undertaken as an evaluation step for environmental lake sediment monitoring. The sonar systems to be evaluated include the subbottom acoustic profiling system
with or without side-scan and the echo sounding system. The subbottom acoustic profiling system operates at low frequencies with great sediment penetration depth (up to 100 m) and provides information on (1) morphological features present on the lake bottom, (2) paleofluvial regimes, (3) present day
control on sedimentation and erosional processes and (4) tectonic activity. This information simplifies sediment sampling surveys and help to interpret geochemical results. The subbottom acoustic profiler in conjunction with the side-scan sonar system generate an accurate representation of the lake
bottom recording vertical, lateral sedimentological variations along with topographical features present at the Jake bottom. The echo sounding system is a high frequency system which records water depth. Most modern system combine low and high frequency sound range satisfying both resolution and
depth penetration requirements for mapping lacustrine sediments. The incorporation of the side-scan sonar along with the subbottom acoustic profiling system is not a cost effective alternative for the purpose of lake sediment monitoring. Grid sampling using a grab sampler can be used to assess the
distribution of geochemical elements in a lake basin. Sampling over a regularly spaced square or triangular grid simplifies and helps to keep track on the sampling site location for a uniform coverage of the sampled area. The Wildco-Dredge or the Petite Ponar type grab sampler can be used to sample
surficial lake sediments. The Petite Ponar sampler seems to be more reliable and flexible to sample all types of sedimentogical environments (shallow-deep waters and/or high inorganic sediments).
Effect of different surface finishing/polishing procedures on color stability of esthetic restorative materials: A spectrophotometric evaluation
Authors: Beltrami Riccardo , Ceci Matteo , De Pani Gabriele , Vialba Lodovico , Federico Ricaldone , Poggio Claudio , Colombo Marco
Published: March 2018

Objective: To evaluate the color stability of different esthetic restorative materials after surface finishing/polishing with different procedures. Materials and Methods: All materials were polymerized into silicone rubber rings to obtain specimens identical in size. Samples were randomly assigned into four groups (10 specimens of each composite for each group), and they were finished with different procedures: Control group (Group 1), three or two polishers interspersed with diamond grit (Groups 3 and 2, respectively), and one tungsten carbide bur + one polisher interspersed with diamond grit (Group 4). After staining process in coffee, a colorimetric evaluation according to the CIE L*a*b* system was performed by a blind trained operator at 7, 14, 21, and 28 days. Shapiro–Wilk test and Kruskal–Wallis analysis of variance were applied to assess significant differences among restorative materials. Means of the different polishing/finishing groups were compared with Scheffe’s multiple comparison test at the 0.05 level of significance. Results: In control group, significant lower discolorations were recorded for Essentia, Admira Fusion, and Estelite. After finishing, Filtek Supreme XTE and Ceram.X Universal showed a significantly lower degree of staining. The finishing technique used for Group 4 produced higher color changes. Conclusions: Tungsten carbide burs produced the higher color variations; after finishing, the nanofilled composites showed lower discoloration than nanohybrid ones, and the time of exposure to the staining agent and the polishing/finishing technique influenced the color change.
Dental caries prevalence and its association with fluoride level in drinking water in Sana’a, Yemen
Authors: Al-Akwa Ameen Abdullah , Al-Maweri Sadeq Ali
Published: March 2018

Objectives Dental caries is the most prevalent chronic condition affecting schoolchildren worldwide. This study is aimed to assess the prevalence of dental caries among schoolchildren in urban and rural districts of Sana’a governorate, Yemen, and to investigate the correlation between caries experience and level of fluoride in drinking water, age, gender, and residence. Materials and Methods This school-based survey involved 17,599 schoolchildren (aged 6-12 years), of whom 9623 were boys and 7976 were girls. We used decay-missing-filled teeth/decay-filled teeth (DMFT/dft) indices to evaluate dental caries experience. In addition, fluoride concentration in drinking water was investigated. Results Around 67.6% of children had dental caries. Children residing in urban districts had significantly higher mean scores of DMFT/dft than those in rural areas (P < 0.05). A significant negative correlation between caries experience and fluoride level was found (P < 0.05), with the lowest dft/DMFT scores at the optimum fluoride level of 0.61-2 ppm and the highest at two extremes, 0.0–0.4 ppm and >2 ppm. Conclusion: This survey found a very high prevalence of caries among schoolchildren in Yemen. There was also an inverse relation between dental caries experience and fluoride levels.
Cariogenicity induced by commercial carbonated beverages in an experimental biofilm-caries model
Authors: Giacaman Rodrigo A. , Pailahual Vanesa , Díaz-Garrido Natalia
Published: March 2018

Objectives Frequent consumption of sugars-containing carbonated beverages has been associated with caries, but the consequences on the dental biofilm remain unclear. The aim was to evaluate the effect of commercial carbonated beverages and their sugar-free version on enamel and dentine demineralization and on the cariogenic properties of Streptococcus mutans biofilms. Materials and Methods Biofilms of S. mutans UA159 were grown on enamel and dentin slabs and exposed 3 times/ day for 5 min, to a commercial cola or orange-flavored carbonated beverage or to their sugar-free version. Biofilms/slabs were recovered to assess biomass, viable microorganisms, protein content and polysaccharides. Demineralization was estimated by the variation of Knoop surface microhardness. Results Exposures to the biofilm with sugars-containing carbonated beverages resulted in similar biomass, viable microorganisms, proteins, and polysaccharides than sucrose (P < 0.05). The sugar-free cola and orange-flavored drink showed lower effect on the biofilm, as compared with sucrose or their sugared version (P < 0.05). All of the products tested, included the sugar-free, showed higher demineralization than the negative control (P < 0.05). Conclusions: Sugars-containing carbonated beverages enhance cariogenic activity of S. mutans biofilms, comparable with sucrose. Sugar-free carbonated beverages also have a high demineralizing potential, without affecting biofilm properties.
Analysis of vertical marginal discrepancy in feldspathic porcelain crowns manufactured with different CAD/CAM systems: Closed and open
Authors: Kricheldorf Fabio , Bueno Cleuber Rodrigo de Souza , Amaral Wilson da Silva , Junior Joel Ferreira Santiago , Filho Hugo Nary
Published: March 2018

Objective: The objective of this study is to compare the marginal adaptation of feldspathic porcelain crowns using two computer-aided design/computer-aided manufacturing systems, one of them is open and the other is closed. Materials and Methods: Twenty identical titanium abutments were divided into two groups: open system (OS), where ceramic crowns were created using varied equipment and software, and closed system (CS), where ceramic crowns were created using the CEREC system. Through optical microscopy analysis, we assess the marginal adaptation of the prosthetic interfaces. The data were subjected to the distribution of normality and variance. The i-test was used for the analysis of the comparison factor between the groups, and the one-way ANOVA was used to compare the variance of crown analysis regions within the group. A significance level of 5% was considered for the analyses. Results: There was a significant difference between the systems (P = 0.007), with the CS group having the higher mean (23.75 pm ± 3.05) of marginal discrepancy when compared to the open group (17.94 pm ± 4.77). Furthermore, there were no differences in marginal discrepancy between the different points between the groups (P > 0.05). Conclusions: The studied groups presented results within the requirements set out in the literature. However, the OS used presented better results in marginal adaptation.
Impact of malocclusion severity on oral health-related quality of life in an Iranian young adult population
Authors: Dalaie Kazem , Behnaz Mohammad , Khodabakhshi Zahra , Hosseinpour Sepanta
Published: March 2018

Objective: This study aimed to assess the relationship between malocclusion severity and oral health-related quality of life (QoL) of 18 to 25-year-old Iranians who sought orthodontic treatment.

Materials and Methods: A total of 126 patients between 18 and 25 years attending some private orthodontic clinics answered the oral health impact profile-14 (OHIP-14) and a demographic questionnaire. Two calibrated orthodontists recorded the Index of Orthodontic Treatment Need-Dental Health Component (IOTN-DHC) determining the severity of malocclusion (Kappa = 0.8). The IOTN-Aesthetic Component (IOTN-AC) was reported by patients for assessing the perception of their esthetic severity of malocclusion. Logistic regression analysis was used. Level of significance was set at ⍺ = 0.05.

Results: The mean score of OHIP-14 was 20.87 ± 8.6. The frequency of patients with no/slight, borderline, and definite need for orthodontic treatment was determined as 13.4%, 23.8%, and 62.7%, respectively, by IOTN-DHC. There were significant correlations between borderline or definite need treatment and OHIP-14 overall score (P < 0.05). Patients with borderline and definite need for orthodontic treatment had 5 and 21 times lower QoL, respectively, than those with a slight need for orthodontic treatment. Based on IOTN-AC, 50.8% of the patients mentioned slight or no need based on IOTN-AC. No significant association was noted between IOTN-AC and OHIP-14 overall scores.

Conclusions: The results showed negative impact of malocclusion severity on the QoL. This study highlighted the importance of individual assessment of orthodontic patients.
Relationship between Expanded Disability Status Scale scores and the presence of temporomandibular disorders in patients with multiple sclerosis
Authors: Carvalho Lucas Senra Correa , Nascimento Osvaldo José Moreira , Rodrigues Luciane Lacerda Franco Rocha , Matta Andre Palma Da Cunha
Published: March 2018

Objectives: The objectives of this study were to assess the prevalence of temporomandibular disorders (TMDs) in patients with relapsing-remitting multiple sclerosis (MS) and to investigate whether an association exists between the presence of TMD symptoms and the degree of MS-related disability. Materials and Methods: In all, 120 individuals were evaluated: 60 patients with a diagnosis of relapsing-remitting MS and 60 age- and sex-matched controls without neurological impairments. A questionnaire recommended by the European Academy of Craniomandibular Disorders for the assessment of TMD symptoms was administered. For those who answered affirmatively to at least one of the questions, the RDC/TMD Axis I instrument was used for a possible classification of TMD subtypes. The Expanded Disability Status Scale (EDSS) was the measure of the degree of MS-related disability. Statistical Analysis Used: Fisher’s exact test was used to analyze the data. ANOVA was used to detect significant differences between means and to assess whether the factors influenced any of the dependent variables by comparing means from the different groups. Results: The prevalence of TMD symptoms in patients with MS was 61.7% versus 18.3% in the control group (CG). A diagnosis of TMD was established for 36.7% in the MS group and 3.3% in the CG (P = 0.0001). There were statistically significant differences between degrees of MS-related disability and the prevalence of TMD (P = 0.0288). Conclusions: The prevalence of both TMD and TMD symptoms was significantly greater in the MS group. EDSS scores and TMD prevalence rates were inversely related.
A propos de l’emploi d’un glucocorticoïde en traumatologie vertébrale canine
Authors: Willemart Jean-Pierre
Published: March 2018

Malgré l’utilisation d’une posologie plus élevée (250 à 400 mcg/kg) d'acétate de dexaméthasone que celle habituellement recommandée (100 à 200 mcg/kg) nous n’avons remarqué aucun effet secondaire, sauf dans un cas. La guérison est apparue rapidement dans huit cas sur douze et deux rechutes ont été constatées. Ce traitement semble pouvoir offrir une alternative à la cure chirurgicale.
Technique de la transplantation du tendon par insertion, chez le cheval de course
Authors: Lesaffre R.
Published: March 2018

La technique chirurgicale classique pour effectuer la transplantation de tendon est simplifiée. Cette simplification élimine pratiquement les complications post-opératoires. Elle permet, en outre, d'entreprendre avec plus de chances de succès les tentatives de récupération de sujets inévitablement condamnés.
Tuberculose à bacille bovin chez les vaches laitières traitées par Mycobacterium chelonei anergiques à la tuberculine bovine
Authors: Thorel M. F.
Published: March 2018

Isolement de Mycobacterium bovis à partir de lésions recueillies sur des bovins traités, régulièrement, par M. chelonei. Si ce dernier n’exerce aucune protection vis-à-vis du bacille tuberculeux, son administration peut entraîner une désensibilisation à la tuberculine aviaire.
L'enlèvement des déchets d’abattages dans les abattoirs publics (Définition, Législation, Jurisprudence)
Authors: Fleckinger Robert
Published: March 2018

Les litiges au sujet de l’enlèvement des déchets et détritus d’abattage dans les abattoirs publics ont permis d’établir une jurisprudence au niveau du Conseil d’Etat.

La présente note, après définition des déchets concernés et revue de la législation, précise cette jurisprudence aux termes de laquelle les dépenses dudit enlèvement incombent aux usagers et peuvent être recouvrées sous forme d'une redevance de prestation de services assise au kg de viande nette.