Bismuth Powder Research Articles

Catalytic Reduction of Nitroarenes to Azoxybenzenes With Sodium Borohydride in the Presence of Bismuth

Abstract Aromatic nitro compounds have been found to be selectively reduced to azoxy compounds in good yields by NaBH4 in the presence of bismuth powder.

Novel reductive coupling of aldimines to vicinal diamines

Reductive coupling of aldimines into vicinal diamines has been performed by the action of aluminium/ bismuth powder and potassium hydroxide in methanol at ambient temperature in high yields.

Sintering of bismuth powder

Bismuth powder, of 99.1% purity and of average particle size 6 μm, is shown to sinter readily over a wide range of temperatures in air, glycerol or vacuum if certain precautions are taken. In air, the sintering temperature should be low (<0.78 T M ); in glycerol, both low sintering temperature (<0.78 T M ) and time (<100 min) are necessary. Maximum densification is obtained in vacuum, but excessive pressure (>4000 lb in −2) or sintering temperature (>0.8 T M ) result in non-uniform shrinkage of the compact.

Application of the theory of errors in the sedimentation analysis of a bismuth powder

Application of the theory of errors in the sedimentation analysis of a bismuth powder

Formation of a fine bismuth powder on the cathode

1. The process of precipitation of dispersed bismuth on the cathode was investigated, and the optimum conditions for the formation of a fine powder were determined. The maximum powder current efficiency lies in the region of limiting current densities. 2. It was observed that precipitation of dispersed bismuth into the organic bath layer occurs at the potentials of SAA desorption from the cathode. The presence of cyclohexanone in the organic layer decreases cathode polarization. 3. To produce a fine bismuth powder, it is necessary to ensure a sufficient degree of cathode polarization, which may be achieved by adding polarizing agents to the electrolyte.

Production of bismuth powder by the reduction of bismuth oxide with a mixture of molecular and atomic hydrogen

1. Bismuth powder can best be produced from freshly preparedα-Bi2O3, by reduction with a mixture of molecular and atomic hydrogen at 270‡C. 2. Theα-Bi2O3→Bi reduction reaction appears to take place without the formation of any intermediate phases. Up to 300‡C, the reduction is due to a diffusion mechanism, while at higher temperatures it occurs through a diffusion-kinetic mechanism, yielding dense bismuth.

482. 粉末充填型セラミック燃料体と被覆管との間に挿入したビスマス熱媒体の挙動

Evaluation by out-of-pile heating experiment was made on two types of bismuth heat transfer bonding between powder compacted ceramic fuel and cladding, 1) vibration compaction of a mixture of ceramic fuel powder and bismuth powder in cladding tube, 2) vibration compaction of ceramic fuel powder in cladding tube with bismuth lamella formed on the inner surface of cladding. The principal results were as follows:(1) In the first case of mixed UO2 and bismuth powder, the bismuth originally distributed in the central region of the compact (2, 600°-2, 700°C) evaporated and moved toward the periphery (800°-900°C) where it assembled to serve as good liquid heat transfer medium.(2) In the second case, the bismuth lamella served as good liquid heat transfer medium without permeating into the inner regions of the compact.(3) There was no appreciable reaction between the bismuth and UO2 up to 2, 600°- 2, 700°C, nor between the bismuth and UN or UC up to 1, 20O°-1, 300°C.

Nuclear Magnetic Resonance in Bismuth Metal

The nuclear magnetic resonance in bismuth metal powder has been observed from 9 to 19 Mc/sec at 4.2\ifmmode^\circ\else\textdegree\fi{}K. The isotropic and anisotropic Knight shifts and the quadrupole coupling constant have been determined as (-1.25\ifmmode\pm\else\textpm\fi{}.30)%, (-0.3\ifmmode\pm\else\textpm\fi{}0.3)%, and 2.10\ifmmode\pm\else\textpm\fi{}.05 Mc/sec, respectively. The intrinsic linewidth was found to be 130\ifmmode\pm\else\textpm\fi{}20 kc/sec. A technique is developed to take into consideration the broadening of the observed lines due to the combined effects of the magnetic dipolar broadening and the width due to the quadrupolar splitting of each line.

Synthesis of organobismuth compounds via dia ryliodonium salts

1. A method was developed for the synthesis of organobismuth compounds via diaryliodonium salts. By this method we prepared the following compounds: triphenylbismuthine, tri-p-tolylbismuthine, tris-p-methoxyphenylbismuthine, tris-p-bromophenylbismuthine, tris-p-chlorophenylbismuthine, tris-p-nitrophenylbismuthlne, and bis[methoxycarbonyl)phenyl]bismuth chloride. 2. The decomposition of iodonium salts with bismuth powder with formation of organobismuth compounds occurs only in presence of bismuth trichloride. 3. It is suggested that the initial products of the decomposition of iodonium salts with bismuth are compounds of the types ArBiCl2 and Ar2BiCl. 4. The decomposition of diphenyliodonium chloride, bromide, and iodide with bismuth powder was carried out in presence of BiCl3. In the case of diphenyliodonium iodide the yield of triphenylbismuthine was considerably lower than in the decomposition of diphenyliodonium chloride.

A Technique of Bronchography with Visciodol: A New Contrast Medium

Since the first bronchography was performed by Chevalier Jackson’ in 1918 with the use of bismuth powder insufflated through a bronchoscope, there has been a constant search for more satisfactory bronchographic contrast media. The procedure did not gain widespread acceptance until the epoch making discovery by Sicard and Forestier2 in 1923, that Lipiodol made a satisfactory contrast medium for this examination. Other iodized oils were subsequently introduced, but none was able to surmount the following common objections to their use for this procedure: 1) Retention within the alveoli obscures any accurate follow-up for long periods of time, as elimination from the lung is slow. 2) The retained iodine interferes with any subsequent radiation therapy.8 3) Delay in any contemplated pulmonary surgery due to an increased incidence of post-operative atelectasis in cases having had recent bronchography with alveolar penetration.4 4) Alveolograms are far more difficult to interpret than bronchograms. 5) Reported formation of iodized oil granulomas.5 6) Prolongation of reactions in iodine sensitive individuals due to slow liberation of iodine. 7) Repeat bronchograms impossible for long periods of time due to obscuring shadows of alveolar oil. These objections led to the introduction of water-soluble contrast agents. loduron B and Umbradil Viscous B were introduced in 1948. More recently Dionosil Aqueous in a carboxymethylcellulose base has become available. These agents are not without their own particular group of inherent objectionable qualities. We feel, as do other workers,#{176} that these objectionable qualities makes their use as undesirable as the use of the unaltered iodized oils for this procedure. The chief objections to the use of these water-soluble agents are: 1) They produce severe local irritation and require deep topical anesthesia.6’ 7 2) The radiographic images produced by these agents are less dense than those produced by the iodized oils due to lower iodine content. This is particularly important on the lateral projection.8 3) Undue haste must be employed during the procedure due to their rapid absorption. 4) The carboxymethylcellulose present as the base of these agents has

New Displacement Technic for Study of Gastric Mucosal Relief

CAREFUL analysis of existing contributions often reveals that which we consider original is merely an adaptation, revival, or refinement of previous labors. In fact, completely original departure in our state of organized knowledge is highly improbable. This study of the mucosal folds of the stomach is presented as an adaptation and revival of a known technic. It is a surprising fact, not superficially recognized, that the x-ray examination ofthe stomach still escapes absolute recognition of criteria which should make diagnos is a relatively simple matter, although the stomach was one of the first internal organs to be visualized by artificial ingestion and one which has received a major amount of attention. The recognition of early carcinoma of the stomach has become progressively more difficult and baffling. This is not the result of lack of interest in the stomach, because the literature shows an increasing number of articles directed to it. However, if we are to make an early diagnosis of any lesion of the stomach, particularly carcinoma, it is imperative that minute studies of the mucosal relief should be made. It follows, therefore, that newer methods should be employed in order to emphasize the finer mucosal markings to such a degree that the rugal folds can actually be studied with a magnifying glass to effect macroscopic visibility for evidences of morphologic changes. To this end, as early as the turn of the century, Einhorn employed a blower with bismuth powder to coat the stomach, and Holzknecht and Brauner used gas distention with tartaric acid and natrium bicarbonate. Later, various methods of palpation and allowing the bismuth to settle out of suspension (1) were used to demonstrate the mucosal folds. In 1911 the method of inflating the stomach with air was used (2) in combination with a contrasting emulsion. Akerlund (3) used external pressure over the duodenal bulb, displacing all but a thin layer of the opaque solution. In this way rapid progress was being made in the visualization of the mucosal folds. In 1923 a significant point of departure was established by Forssell (4), who drew attention to the mucosal movements independent of peristalsis. This constituted one of the first deliberate attempts to focus attention on the rugæ per se. This contribution to the anatomy of the mucosal membrane of the stomach by means of anatomical pressure succeeded in demonstrating the coil-like rugal folds on the anterior portion of the stomach and the less frequent longitudinal folds of the posterior wall. The remainder of the mucous membrane on the posterior wall was found to be contracted through the building up of a mammillated surface, the so-called “état mammelonné” (Fig. 1). Forssell's studies indicated that the mucous membrane could produce a folding and contraction independent of the peristaltic waves.

Flesh Contour in Radiograms

It is a curious fact that whilst an X-ray negative shows the contour of the soft parts very distinctly, the print from such either does not show it or shows it indistinctly, unless special precautions are taken, when there is a danger of the definition of the bones being interfered with. Many observers have noticed this and adopted special means to remedy it, most of them being elaborate and tedious. It was first brought to my notice when preparing a series of X-ray pictures of fractures for demonstration purposes. To my surprise the print appeared to have lost the reality of the negative. The skin may be “brought out” by over-exposure, but only at the expense of bony definition. There have been numerous attempts to remedy this loss. At one time, Hall Edwards (Birmingham) dusted the part with Bismuth powder before exposing; the method was not applicable to diseased conditions, as it obscured bony definition. The French spent much time on the problem during the war. The late Alexander (Vienna) superimposed...

The Hall Effect in a Bismuth Crystal

The Hall effect has been measured in plates cut in different directions from a single large crystal of bismuth. At room temperatures when the field $H$ is perpendicular to the trigonal axis, a negative Hall coefficient $R$ is obtained, decreasing from about 15 for $H=1000$ gauss to about 7 for $H=8000$. For $H$ parallel to the trigonal axis a positive coefficient of about unity is obtained, increasing slightly with the field. At -186\ifmmode^\circ\else\textdegree\fi{}C $R$ is positive for all orientations of the axis and decreases as $H$ increases. The maximum $R$ observed at -186\ifmmode^\circ\else\textdegree\fi{}C was + 15 at $H=600$. A plate made of compressed bismuth powder gave $R=+7$, approximately, at -186\ifmmode^\circ\else\textdegree\fi{}C. Beckman found large negative values of $R$ for similar plates at this temperature. The Hall e.m.f. cannot be resolved into positive and negative components at -186\ifmmode^\circ\else\textdegree\fi{}C in the way suggested by Becquerel.