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Etude de la fissuration intergranulaire en corrosion sous tension dans une solution NH 4 OH-NaOH-H 2 O (essai de traction sous charge constante a 303 K) des bicristaux d'alliage Cu-9at% Al de differents caracteres cristallographiques

In order to study the effect of grain boundary on stress corrosion cracking (SCC) of α-brass, SCC tests were carried out on Cu-30.6 at%Zn alloy bicrystals in ammoniacal vapor at 303±2K. The susceptibility of the grain boundary to SCC was found to be higher than that of slip step sites in the present bicrystals with an about 15° off-coincidence Σ=13b boundary surface energy although it has been regarded to be as high as that of the so-called general boundary. Tubular pits which are considered to be initiated by the mechanism proposed by Pickering and Swann were mostly observed at the grain boundary and rarely on the crystal surface. Fine cracks propagating along the trace of {110} or {111} in the grain interior were observed not to grow into the main crack responsible to fracture.

The effects of grain boundaries on stress corrosion cracking (SCC) of Cu-Zn and Cu-Al alloys have been studied employing various types of orientation-controlled bicrystals. It was found that SCC susceptibility in Cu-Zn alloys decreases in the following order; beta-phase crystal surface, (alpha/alpha)-grain boundary, alpha-phase crystal surface, diffusion-induced twin boundary in alpha phase, (beta/beta)-grain boundary or (alpha/beta)-interphase interface. It was also clarified that, in an alphaCu-Al alloy, the grain boundary shows much higher susceptibility than the grain interior. The susceptibilities of the symmetrical - and -tilt, and the - twist boundaries of the alphaCu-Al alloy to SCC are strongly dependent upon the misorientations. Sharp minima indicating great resistance to SCC exist at some angles, which correspond to relatively small sigma-values. Moreover, the susceptibility of a grain boundary to SCC is much enhanced by a stress field arising from pile-up dislocations in the immediate vicinity of the boundary. It becomes evident that the susceptibility to intergranular stress corrosion cracking is suddenly decreased when the grain boundary misorientation decreases below approximately 15°. This may result from the increased number of dislocations passing through the boundary with decreasing the misorientation angle, by which a stress concentration is avoidable.

An improved solid-solid diffusion method to produce ideal macroscopic two-phase (∝/β)-brass bicrystals suitable for mechanical testing, having nearly uniform and thermodynamic equilibrium concentrations, has been established. The resulting bicrystals were found to contain no twinned structure and recrystallization gains in the ∝-phase, which usually appear in the ∝-phase of two-phase (α/β)-brass bicrystals when a steep concentration gradient in the phase is present.

Etude du mecanisme de formation de «pli» au point triple permettant de suivre le comportement de la jonction triple du joint de grain en employant des tricristaux d'orientation controlee soumis a des essais de fluage a 773 K. Caracterisation de l'origine de ces plis en tant que bande de glissement. Les plans actifs sont {111} et {100} et contiennent les lignes des joints de grains triples

Clinical statistics were conducted on 511 hospitalized cases of jaw fractures at the Department of Oral Surgery, Mie University Hospital during the 24-year period from 1960 to 1983.Inpatients in this period totaled 2, 290 cases.The incidence of fractures was 24.1% of all inpatients.1) The number of patients with jaw fractures each year tended to increase from 1960 to 1970, but there was almost no change from around 1971 to 1983.2) The male/female ratio was 4.5: 1, but the ratio in the past eight years narrowed the gap to 3.5: 1.3) The seasonal variation in the incidence of fractures was not significant.4) The most common causes of injury were traffic accidents in both males and females, especially female fractures were more by traffic accident than from any other cause.5) Fracture of the incisive region was the most common.6) The average fixation time for old fractures was slightly longer than that of fresh fractures but in the past eight years there was no difference between them, and it tended to be shorter.

The nature of BaF 2 emission is investigated by measuring excitation spectra using synchrotron radiation for the energy range up to 40 eV. Intense emission bands, appearing at 5.6 and 6.4 eV in the Auger-transparent region, are ascribed to a radiative decay of valence electrons into Ba 2+ 5 p core holes. This luminescence process of a new type is discussed.

(1983). AN IMPROVED METHOD FOR THE PREPARATION OF 2-SUBSTITUTED 1,2-BENZISOTHIAZOL-3 (2H)-ONES. NOVEL CYCLIZATION OF N-SUBSTITUTED 2-CARBAMOYLBENZENESULFENYL BROMIDES ON ACTIVATED BASIC ALUMINA. Organic Preparations and Procedures International: Vol. 15, No. 5, pp. 315-319.

Etude de l'effet de la jonction triple sur la deformation a haute temperature des tricristaux d'aluminium soumis a des essais de fluage a 773 K. Influence de l'axe de traction, des orientations respectives des joints de grains, et des orientations cristallographiques des grains sur le comportement a la deformation

We studied Cefotetan (CTT) concentration of serum and oral tissues (cortical bone, alveolar bone, gingiva, hard plate mucosa, buccal mucosa, maxillary bone, tongue, mandibular bone, cancellous bone) in 29 patients and similar experiments in 30 rats, and the following results were obtained.(1) In rats, CTT was administered in a dose of 40 mg/kg by intravenous injection.The highest concentration was obtained in hard plate mucosa and followed in gingiva, mandibular cortical bone, tongue, submandibular gland, mandibular bone and maxillary bone at 10 minutes after administration.(2) In humans, CTT in a dose of 2 g was administered by intravenous injection.Among gingiva, alveolar bone and cortical bone, the highest concentration was observed in gingiva. Peak concentration in gingiva was 62.6% of the corresponding serum value.In alveolar bone and cortical bone, they were 14.5% and 10.4%.(3) In cortical bone, as from 90 minutes after administration, no detectable cases were observed in measured 6 cases, therefore, it is assumed that CTT may be rapidly excreted from cortical bone in comparison with other tissues.(4) On the bases of these results, it was concluded that CTT is a useful antibiotic for the treatment of oral infection.

The reflection and transmission spectra have been measured for thin NaI, KI, RbI and CsI single crystals with 0.1∼0.3 µm thickness at 11 K. Pronounced structures due to the Fabry-Perot interference are observed in the vicinity of the exciton resonance, showing a strong dispersion of the refractive index. By fitting the obtained results with the theoretical dispersion formula we determine the background dielectric constant, the transverse exciton energy and the longitudinal-transverse (L-T) splitting for each iodide. The present values of L-T splitting are compared with the ones determined from different experiments or calculated independently from the oscillator strength of excitons. On the basis of these experimental values, the validity of the polariton concept in alkali iodide crystals is discussed.

The new scintillation material CsI has been investigated for a position sensitive detector which is used together with CsI(Tl) coupled to a common PMT. Spatial resolution has been achieved with a simple pulse shape discriminator. Combinations of CsIBGOCsI(T1) and CsIBaF 2 CsI(T1) are also shown to be useful as position sensitive detectors.

A new automatic system to analyze the orientations of the crystallographic axes of arbitrarily oriented cubic crystals using the back-reflection X-ray Laue method has been developed. The system consists of a tablet digitizer to input the coordinates of Laue spots, an usual microcomputer to index Laue patterns and a plotter to output stereographic projection.The accuracy of the analysis was remarkably improved in comparison with the traditional method of indexing with Greninger chart and Wulff net; it is estimated to be less than 0.1-0.2° in consequence of optimizing the rotation of standard projection and compensating the distance between specimen and film by computation. The time required is about ten minutes.

La reaction conclut a un seul produit dont l'identification possible est le tetramethyltetroxanne-1,2,3,4

Excitation spectra of visible luminescence in CsF (2.5-5.6 eV), CsCl (3.9-6.0 eV), CsBr (4.4-6.2 eV), and RbF (2.6-6.2 eV) have been measured at room temperature with use of synchrotron radiation for the energy range up to 40 eV. It is shown that the excitation thresholds of these luminescence bands are located at the transition energies from the outermost-core band to the conduction band. This fact provides direct evidence for the radiative decay of valence electrons into outermost core holes in which the Auger decay process is energetically impossible in these materials.

The infrared CN stretching bands of acetonitrile in neat liquid and in dilute solution in carbon tetrachloride have been measured at various temperatures. The reorientational and vibrational relaxation times obtained from temperature dependence of the ν2 fundamental bandwidth are consistent with previous Raman results. The reorientational relaxation times are linear in the viscosity divided by the temperature and the proportional constants for the neat liquid and the dilute solution agree with each other within experimental uncertainty. This fact indicates that the effect of the dipole-dipole interaction on the molecular reorientation is included in the viscosity and the proportional constant is characteristic of the molecule, which is consistent with a hydrodynamic theory. Molecular dynamics calculations of liquid acetonitrile were performed at several temperatures with two types of pair potential, with and without Coulomb terms in addition to the atom-atom Lennard-Jones terms. Comparison of the calculated reorientational relaxation times with the experimental results shows that the dipolar interaction plays an important role in the molecular reorientation in liquid acetonitrile.

The very thin KI crystal has been grown from the melt inside a narrow gap of the cell composed of two quartz plates. Thickness of the crystal is determined to be about 0.2 µm from the interference fringes in the transparent region. Consequently, the transmitted light can be detected up to the absorption coefficient of 3 ×10 5 cm -1 . From the measurements of absorption and reflection spectra, it is shown that the 2 s exciton band consists of the oscillatory structures separated by about 16 meV, in contrast to the case of evaporated thin films.

The properties of pure CsI have been studied with respect to its application as a scintillation material.

Polarized reflection spectra of uniaxially-strained RbI and KI crystals have been measured in oblique-incidence geometry at 11 K. A structure has been observed in the p-polarized spectrum on the high-energy side of the 1s exciton peak. This structure is attributed to the longitudinal exciton, which is caused by a uniaxial-stress field.

The absorption spectra have been measured on thin RbI crystals at 11 K. When the crystal thickness decreases below 0.5 µm, new absorption peaks are found to appear on the low-energy side of the n =1 and n =2 exciton bands. From measurements of the thickness dependence, these additional structures are interpreted as being due to the pure triplet exciton states induced by the strains in thin crystals.

In many of the typical thermosetting acrylic polymers, functional groups are incorporated as comonomers so that crosslinking can occur. In this study N-butoxymethyl amide was used as comonomer to introduce functional groups and melamine resin was added so that crosslinking can occur through self-condensation of the base acrylic polymer as well as through reaction with melamine.Chemical stress relaxation of swollen films in boiling water was determined. In continuous relaxation, a rapid decay of stress occurred at the early stage which probably is due to the loss of unreacted melamine. Subsequent decay of stress was found to follow the following function consisting of three exponential terms:f(t)/f(0)=Aexp(-k1t)+Bexp(-k2t)+Cexp(-k3t)With intermittent relaxation, when the degree of crosslinking is low, relative stress f(t)/f(0) was found to decrease at first and then to increase sharply at around 60∼100min. This increase indicates the crosslinking caused either by the unreacted melamine resin or the recombination of the scissions that had occurred earlier.

The photochemical reaction of a series of 2-aryl-1,2-benzisothiazol-3(2H)-ones (1) under deaerated conditions was found to give dibenzo[b,f][1,4]thiazepin-11(10H)-ones (2). A mechanism through a biradical species is proposed for the photoreaction. When the photolysis of 1 was carried out in the presence of oxygen, 2-aryl-1,2-benzisothiazol-3(2H)-one 1-oxides (11) were formed together with compounds 2.

The photolysis of spiro[benzo[b]thiophene-2(3H),1′-cyclopropan]-3-one 1,1-dioxide (1) in benzene afforded 2-biphenylyl cyclopropyl ketone with extrusion of sulfur dioxide, whereas the irradiation of 1 in toluene or p-xylene formed photoreduced dimer and bibenzyl or 4,4′-dimethylbibenzyl, respectively. The photolysis of spiro[benzo[b]thiophene-2(3H),1′-cyclopropan]-3-one in benzene afforded the valence isomer 2,3-dihydro[1]benzothieno[3,2-b]furan.

La reaction conclut a un seul produit dont l'identification possible est le tetramethyltetroxanne-1,2,3,4

A study was made on the induction of sister-chromatid exchanges (SCE) in cultured Chinese hamster V79 cells exposed to the photochemical reaction products of toluene plus NO2 in the gas phase. The photochemical reaction products of toluene plus NO2 were obtained by photochemical reaction of a toluene--NO2/dry air system in a photochemical smog chamber and then exposed to cultured cells for 2 h using a system for in vitro gas exposure. SCEs were induced at all concentrations of the photochemical reaction products employed in the present study, and the highest SCE frequency observed for the highest concentration tested for each component was 3.6 times higher than that of the control. Cytogenotoxicity which was evaluated with induced-SCEs of the photochemical reaction products of toluene plus NO2 was much the same as that of the previously reported photochemical reaction products of propylene plus NO2 (Shiraishi and Bandow, 1985), but was considerably stronger than that of typical gaseous air pollutants such as NO2 alone and O3 alone.

In a 73-year-old man with acute myelomonocytic leukemia (M4 on FAB classification) Auer rods were demonstrated in mature granulocytes and monocytes in the blood as well as the bone marrow. Cytochemically, a significant number of leukemic blasts were positive for both alpha-naphthyl-acetate esterase and naphthol-AS-D-chloroacetate esterase. Auer rods in mature granulocytes were associated with immature cytoplasm and not infrequently with pseudo-Pelger anomaly. The significance of these observations is discussed.

Compact tension (CT) shaped copper bicrystals containing the Σ3(111), Σ9(221), Σ41(338) or random [110] tilt boundaries either perpendicular or parallel to the tensile axis (TA) were tested to examine the effect of grain boundary (GB) structure on fatigue crack initiation and propagation. With both types of bicrystals, the GB resistance to intergranular cracking increases with the decrease in the Σ value. The effect of air on fatigue crack propagation is found to be of primary importance. It is shown that the GB is not necessarily a preferential site for crack propagation in vacuum. A crack introduced intergranularly in air may assume a stransgranular mode of growth in vacuum. The initial GB structure greatly affects the susceptibility of GBs to corrosion in air and this determines their resistance to crack growth. The relative importance of slip band cracking as compared to GB cracking in vacuum is examined. The dominant mechanism of fracture is seen to be determined by two factors: the GB structure in the non-equilibrium state and the geometry of slip with respect to GB orientation.

Misorientation-dependent intergranular stress-corrosion-cracking (SCC) in a series of alpha Cu-Al alloy bicrystals is reviewed, with the focus on the authors' work. The research programme employing precisely oriented bicrystals would lend much to the understanding of intergranular SCC depending on the structure and energy of a grain boundary. The susceptibilities of the symmetrical tilt and twist boundaries to SCC are strongly dependent upon the misorientations

The effect of environment on fatigue crack propagation in copper compact tension (CT) bicrystals was examined. The role of the initial grain boundary (GB) structure is analyzed for bicrystals having Σ9 and Σ41 grain boundaries. It is shown that the GB is not necessarily a preferential site for crack propagation in vacuum. A crack introduced intergranularly in air may change its mode of growth to transgranular in vacuum. The relative importance of GB cracking compared with persistent slip band (PSB) cracking in vacuum is examined. The dominant mechanism of fracture is determined by two factors: the GB structure and the geometry of slip with respect to the GB orientation.

The significant enhancement of strength is reported for pure K24 gold and its K18 alloys subjected to grain refinement by equal channel angular pressing (ECAP) in comparison with their annealed or ordinary cold-worked counterparts. The effect of strain path on the tensile behavior is discussed from the stand point of mechanical properties and damage evolution during straining. It is shown that although different processing can give rise to substantially different structures, the mechanical properties depend on the pre-strain history only slightly. The ECAP appears to be particularly effective for strengthening of pure gold and Au-Ag solid solutions where the strength can increase by a factor of 3 or 4 while in the precipitation hardenable alloys the effect of grain refinement is masked by other strengthening mechanisms and the strength increases by a factor of 2. The strain localization and features of plastic deformation in ECAP materials are discussed in detail upon in-situ and post-experimental surface observations in differently fabricated samples.

Equal Channel Angular Pressing (ECAP) is one of the effective plastic working processes to achieve metals strengthening. In the present study, the strengthening of Au, Au-25Ag and Au-12.5Ag-12.5Cu (in mass%) by ECAP is examined. The rectangle-shaped working billets were pressed repeatedly with both 0° rotation (route A) and 90° rotation (route Bc) between successive pressings, up to four passes corresponding to equivalent strain of e = 4.6. These samples were then subjected to Vickers hardness and tensile tests. The hardness measurements revealed that, in Au up to four passes, Vickers hardness values of the samples produced by route Bc and route A were Hv117 and Hv98, respectively. Vickers hardness value and the tensile strength of Au-Ag-Cu alloy aged after ECAP are estimated to be of Hv345 and of 1.1 GPa.

Acoustic emission (AE) is investigated during cycling at a constant plastic strain amplitude of ultrafine-grain (UFG) copper produced by severe plastic deformation, aiming at detailed characterization of AE in the time and frequency domain and clarification of fatigue damage mechanisms. The results of AE analysis in UFG copper are compared with those obtained in conventional polycrystals and single crystals. It is shown that fatigue damage and corresponding AE in UFG copper is controlled by three main mechanisms: large-scale shear banding, mode I tensile crack opening and mode II shear crack propagation. No AE that could be associated with ordinary dislocation mechanisms typical for conventional coarse-grain metals was detected in the UFG state. A close connection between strain localization, crack nucleation and grain boundaries in UFG materials is emphasized. It is shown that annealing at a moderate temperature of UFG materials fabricated by severe plastic deformation can reduce the degree of s...

Excitation spectra of luminescence in Cs-halides and RbF have been measured at room temperature using synchrotron radiation for energy range up to 40 eV. The excitation thresholds are at the incident photon energy 13.8 ± 0.2 eV for the 2.5 ≈ 5.6 eV luminescence from CsF, the 3.8 ≈ 6.2 eV luminescence from CsCl, and the 4.4 ≈ 6.2 eV luminescence from CsBr, and 17.0 ± 0.1 eV for 2.8 ≈ 6.2 eV luminescence from RbF. These luminescence (CV-luminescence) are explained in terms of interatomic radiative transition of valence electrons to deeper-lying core holes.

The C band of LiI: Tl is considerably depressed. The ratio in area of the C band to the A band of LiI: Tl is 2.8 which is smaller than those in NaI: Tl, KI: Tl and RbI: Tl. Magnitude of splitting between the C and D bands of LiI: Tl is the largest among these four phosphers. These results suggest that in LiI: Tl there exists strong configuration interaction between two states corresponding to the C and D bands.

The photolysis of spiro[benzo[b]thiophene-2(3H),1′-cyclopropan]-3-one 1,1-dioxide (1) in benzene afforded 2-biphenylyl cyclopropyl ketone with extrusion of sulfur dioxide, whereas the irradiation of 1 in toluene or p-xylene formed photoreduced dimer and bibenzyl or 4,4′-dimethylbibenzyl, respectively. The photolysis of spiro[benzo[b]thiophene-2(3H),1′-cyclopropan]-3-one in benzene afforded the valence isomer 2,3-dihydro[1]benzothieno[3,2-b]furan.

Measurements of absorption and luminescence in LiI crystals have been carried out as a function of temperature. Being extremely hygroscopic, LiI crystals are cleaved in liquid helium inside a cryostat before optical measurements. A drastic change of luminescence spectrum by the sample cleavage is found. From these results, it is concluded that the self-trapped exciton (STE) state in LiI is stable, and from the state one luminescence band peaking at eV is emitted. The STE state in LiI is likely to be of three-center type (I 3 +e) rather than of two-center type (V k +e).

By electron diffraction and X-ray powder diffraction, a new type of A5B3-structure based on the L10-type was found in the Al–Ti and Ga–Ti systems; Al5Ti3 and Ga5Ti3. The structure has a tetragonal symmetry with the space group, P4/m b m, and the lattice constants, 2√2a f and c f, where a f and c f are those of the fundamental L10-type cell. 20 Al (or Ga) and 12 Ti atoms are contained in the unit cell. The structure can be described as follows: it consists of the domains based on the L12, containing 3×2 columns of Ti atoms, and the domain boundaries have the L10-type atomic arrangement.

Photoisomerization of the benzisothiazol-3(2H)-ones (1) gives the dibenzo[b,f][1,4]thiazepin-10(11H)-ones (4) Probably via homolytic cleavage of the S–N bond [(1)→(2)], cyclization of the biradical [(2)→(3)], followed by the formation of an aromatic ring together with 1,7-hydrogen transfer [(3)→(4)].

A growth method has been developed for preparing thin alkali halide crystals of thicknesses from 0.05 to 50 µm. In this method, the melt is introduced, through capillary action, into a narrow gap between two parallel quartz plates and allowed to solidify. Optical properties of these thin crystal have been measured low temperatures. As an example of this, we examine the case of KI, in which the absorption and emission spectra of excitons are discussed in comparison with those obtained in bulk crystals.