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A bacteriocin produced by Pediococcus acidilactici had an inhibitory and bactericidal effect on Listeria monocytogenes associated with fresh meat. MICs were significantly lower than minimum killing concentrations. When meat was inoculated with L. monocytogenes, the bacteriocin reduced the number of attached bacteria in 2 min by 0.5 to 2.2 log cycles depending upon bacteriocin concentration. Meat treated initially with the bacteriocin resulted in attachment of 1.0 to 2.5 log cycles fewer bacteria than that attained with the control. The bacteriocin, after 28 days of refrigerated storage on meat surfaces, was stable and exhibited an inhibitory effect on L. monocytogenes.

Summary Pregnanolone emulsion, a new steroid anaesthetic agent, was administered intravenously as bolus doses to six young healthy male volunteers in a preliminary pharmacokinetic and pharmacodynamic study. The plasma concentration-time curves fitted a two-compartment model. The elimination half-life was between 0.9 and 1.4 hours, volume of central compartment between 0.95 and 2.10 litres/kg, volume of distribution between 3.75 and 5.58 litres/kg and total body clearance between 1.80 and 3.07 (litres/hour)/kg. The excretion in urine of unchanged pregnanolone was less than 0.1%. The pharmacodynamic properties were found to be similar to those of Althesin, with immediate induction of anaesthesia of short duration. The anaesthetic affected haemodynamics only slightly; minor depression of ventilation, with an increase in Paco2, occurred in several of the subjects. Excitation of short duration occurred in one subject during induction of sleep and slight involuntary muscle movements in another subject during sleep. It is impossible to draw any clear conclusions of the clinical efficacy and tolerance from this limited normal subject trial, but pregnanolone emulsion seems worthy of further clinical trial.

We have extended the recently developed quasisteady‐state heat transfer/thermal stress model for glide dislocation generation in Czochralski pulled GaAs to InP and Si. The calculated results are displayed by means of (a) dislocation density contour lines for {100} wafers and (b) a novel ambient temperature (Ta) stability diagram. The latter representation explicitly shows the progressive elimination of dislocation‐free regions with decreasing Ta in GaAs, InP, and Si. It is predicted that unless the diameter is unusually small (∼1 cm), glide dislocations appear at the periphery of both GaAs and InP grown by LEC at a Ta which is only ∼10 °K below their respective melting points. With decreasing Ta the dislocations rapidly spread throughout the interior. In contrast, an 8‐cm‐diam Si crystal is dislocation‐free even at a Ta about 40 °K below the melting point. At this critical Ta glide dislocations which are confined to the circumference begin to generate. Thus, in accord with current crystal growth experienc...

The bubble domain memory was first reported by Bobeck (1) in 1967. His concept was based on the fact that a cylindrical magnetic domain, that is, a small region of reversed magnetic polarity in an otherwise com­ pletely magnetized plate of material, is stable over a convenient range of applied field. The stable cylindrical domain can be moved in the plate under the influence of magnetic field gradients, or it can remain at rest in the plate under a modest uniform applied field. It was, in fact, the behavior of cylindrical domains when viewed through a polarizing micro­ scope under the influence of perturbing magnetic fields that led Bobeck to dub them "bubble domains." The literature on the behavior of mag­ netic bubbles and bubble domain memory design is now quite extensive (2-7) and is not discussed here, but two advantages of the bubble domain memory should be mentioned. First, since the bubble is stable in the pre­ sence of a small field that can be supplied by a permanent magnet, the bubble domain memory is nonvolatile; that is, the information in the memory is not lost when the power to the memory is off. Second,. the bubble diameter can be reduced to about one micrometer so the packing density for information can be quite high. Storage densities of a megabit per square centimeter are now seen in advanced engineering designs. From the standpoint of the materials scien tist, preparation of the memory element for a bubble domain device presents a many-faceted problem that extends over several technical fields. the materials scientist must have a good knowledge of the physics of'magnetic materials, as well as the chemistry of preparation of magnetic materials, bulk crysta:l growth

The choice of magnetic garnet compositions for bubble memories is always a compromise dictated by the material requirements generated by the specifications on the memories. The three compositions reported, Y2.62Smo.38Fe3.85Ga1.15O12, Gd2.lLuO.9Fe4.4Al0.6O12, and Yl.92Sm0.1Ca0.98Fe4.02Ge0.98O12, represent three examples of such a compromise. The first composition is excellent for use in circuits operating at 100 KHz over a temperature range of -20° to 80°C. The second has a mobility up to 5000 cm/sec/0e and is capable of very high speed operation at the sacrifice of stability toward temperature. The third exhibits excellent stability toward temperature and has operated at 1 MHz but is compositionally more complex.

An apparatus using the sessile-drop method is described for determining surface tension and wettability data of liquid-solid systems at elevated temperatures in vacuum and in controlled atmospheres. The relative merits of some of the current methods of metallizing alumina ceramics are evaluated in terms of solder wetting. The wetting by molten brazing metals and alloys is reported as a function of time in terms of contact angle on surfaces of high-alumina ceramics with and without various types of hightemperature metal coatings.

It has been discovered that the formation of the butterfly twin in barium titanate depends on both the average particle size and the particle-size distribution of the starting material. Maximum twin yields occur when the particles have an average size near 1μ with a rather sharp cutoff in the distribution in the large-particle region. All impurities act to decrease twin yield, principally because they interfere with stacking-fault formation which also is necessary for twinning to occur.

Progress has been achieved in perfecting the technique for the growth of ruby from flux and broadening the fluorescent linewidth by Ga additions. Line broadening was achieved in flux‐grown ruby crystals both by the deliberate addition of Ga and by the substitution of O2− by F− during crystal growth. Broadening in excess of 10 cm−1 was obtained due to a combination of these factors. Solubility of pure Al2O3 in PbF2 was found to be reduced about 10% by the addition of 0.02 mole % Cr. Chemical analysis of the crystals shows a concentration gradient exists for Cr but not for Ga.

Cylindrical or “bubble” domains and their propagation are briefly described. The physical properties required for materials used in bubble domain memories are listed and the presently known materials are compared with reference to those properties. Materials are also compared with respect to ease of preparation. The crystal growth techniques used to prepare bubble domain materials are described in detail with emphasis on the growth of rare earth iron garnets. Limitations on bubble domain materials imposed by crystal defects are discussed.

A research program aimed at understanding our earlier line width and anisotropy measurements on YIG has led to a study of ferrimagnetic resonance in doped crystals. YIG crystals have been grown containing appropriate concentrations (∼.01 to 5.0 atomic percent) of various impurities, including the 4f rare earth elements, members of the iron transition group, and several non-magnetic elements. This paper gives new results for the variation of the field for resonance with crystal direction at several temperatures in the liquid hydrogen and liquid helium range. In the case of holmium, sharp peaks in the Hres vs angle curve are seen which vary rapidly with temperature. The corresponding curves for the dysprosium containing sample do not show such sharp variations in (110), and at least in part do not vary with temperature below about 4°K. Though Kittel's recent theoretical results should apparently apply to the peaks in the holmium case, his results for the temperature dependence of the anomaly height and widt...

Magnetically uniaxial epitaxial films of Eu2Er1Ga0.7Fe4.3O12 and Er2Eu1Ga0.7Fe4.3O12 5–20‐μ thick have been grown free of cracks from PbO·B2O3 solutions on (110) and (111) Gd3Ga5O12 substrates, respectively. Bubble propagating T‐Bar and Y‐Bar circuits of nickel‐cobalt‐phosphorus were electrolessly deposited on these films. Operation in excess of one hundred steps has been achieved in T‐Bar and Y‐Bar bubble domain shift registers. Details of the growth procedure, magnetic properties, and circuit preparation are presented.

Homoepitaxial deposits of several rare‐earth orthoferrites have been grown from xPbO:B2O3 solutions. Single‐crystal epitaxial layers to 1‐mm thick of Sm0.55Tb0.45FeO3, TbFeO3, and YbFeO3 have been grown on oriented (001) substrates of the respective materials. Deposition rates of approximately 4 μ/h are utilized during growth. Selection of an appropriate solvent is important for successful growth. Depositions from 20PbO:B2O3(wt) result in excessive heterogeneous nucleation and polycrystalline layers when grown above 990°C. Crystallization of rare‐earth borate interferes with orthoferrite growth when carried out at lower temperatures. The solvent 50PbO:B2O3 (wt) has been found to minimize heterogeneous nucleation and eliminate crystallization of rare‐earth borate. The growth method is described in detail, including design of the platinum boat, temperature profiles and their effects on growth, temperature programming, and the experimental difficulties encountered in utilizing the highly volatile highly corr...

Ferric fluoride (FeF3) is a transparent green uniaxial weak ferromagnet (canted antiferromagnet) with a Curie temperature of 365 °K. FeF3 is far more transparent in the visible and uv than any other known material which has a spontaneous magnetic moment at room temperature. FeF3 at room temperature has 6 absorption bands between 7000 A and the band edge which is at 2440 A. There is a local absorption minimum of α = 4.4 cm−1 in the green at 5225 A. The Faraday rotation is 180 °/cm at 5225 A and increases to 1100 °/cm at 3000 A. The birefringent phase retardation at 5200 A is about 80 000 °/cm. The two indices of refraction are about 1.54 in the visible spectrum.

Single crystals of yttrium orthoferrite (YFeO3) 15 mm in diameter and 28‐mm long have been grown from pure Y2O3–Fe2O3 melts contained in platinum crucibles. At the melting point of YFeO3, 1680±5°C, the equilibrium oxygen pressure over the Y2O3–Fe2O3 system is approximately one atmosphere, hence a modified Bridgman technique was used. A Pt‐40% Rh resistance furnace capable of continuous operation at 1750°C under one atmosphere of oxygen was provided with baffles to obtain the desired temperature profile. Supercooling of pure Y2O3–Fe2O3 melts was found to be excessive, ∼100°C, so the Bridgman‐type crucibles were modified to permit seeding. When growth rates were kept below 1.5 mm/h, crystals exhibiting coercivities as low as 0.009–0.012 Oe were obtained. Crystals grown at high rates or from off‐stoichiometry melts contained several types of defects. Precipitate‐bubble pairs, isolated bubbles, a‐b type twins, cracks and optical density variations have been observed. The origin of these defects and steps taken to eliminate them, as well as their effect on cylindrical domain propagation, are discussed.

A technique is described for the use of large noble metal cans which nearly fill the cavity of an autoclave to be used for hydrothermal crystal growth. This approach provides less deformation of the can thus reducing the probability of the can leaking during operation.

Iron borate (FeBO3) is a transparent, green, room‐temperature weak ferromagnet (a canted anti‐ferromagnet) with a Curie temperature of 348°K. Ferromagnetic resonance measurements, i.e., linewidth, anisotropy fields, and g factor vs temperature and frequency are reported for the first time on this material. A low‐temperature linewidth maximum of unknown origin is also observed. Its narrow linewidth, large magnetic anisotropy, large optical Faraday rotation, and transparency in the green (the latter two reported elsewhere) made FeBO3 of interest for devices such as electronically tunable cavities and filters up to ∼100 GHz and high‐speed magneto‐optic modulators.

N-Nitrosobis(2-hydroxypropyl)amine (ND2HPA) is a potent pancreatic carcinogen in hamsters and induces gastrointestinal and respiratory tract cancer in rats. The precursor amines, diisopropanolamine (Di-PA) and triisopropanolamine (Ti-PA), are used in some manufacturing processes and in cosmetic preparations. We have found low levels of ND2HPA in commercial Ti-PA (21-270 ng/g) and in Di-PA (20-1 300 ng/g) and have demonstrated that ND2HPA is formed from Ti-PA and nitrite in a yield comparable to that observed for formation of N-nitrosodiethanolamine (NDELA) from triethanolamine under relatively mild conditions. After reaction for 4 h at 37 degrees C (10 mmol/L amine, 40 mmol/L nitrite, pH 3.0), the ND2HPA yield was 0.51%. The NDELA yield under the same conditions was 0.96%. ND2HPA was determined by gas chromatography-thermal energy analysis (GC-TEA) and GC-high-resolution mass spectrometry (GC-MS) selected ion monitoring of the tert-butyldimethylsilyl (t-BDMS) ether after extraction on a Celite 560 column. The t-BDMS ethers of ND2HPA and NDELA yielded intense, structurally significant peaks at m/z 333.2030 and 305.1716, respectively. The GC-MS procedure provides sensitivity and selectivity comparable to that of GC-TEA.

The anaesthetic activity of pregnanolone (a metabolite of progesterone) in emulsion formulation administered intravenously to male mice was compared with that of Althesin. The loss of righting reflex for 15 seconds was used to estimate the anaesthetic effect. The mean anaesthetic dose (AD50) for the pregnanolone emulsion was 5.25 mg/kg and for Althesin, 2.8 mg/kg. The mean lethal dose (LD50) was 44 mg/kg for pregnanolone and 54 mg/kg for Althesin. The sleeping time after pregnanolone was 2.5-3.5 times longer than after Althesin in dosages above 7.5 mg/kg. No signs of pain or local reaction from injection were observed for either of the drugs. The onset of action was fast for both drugs, with only minor signs of excitation, and recovery was rapid and without excitation. The results indicate that the anaesthetic properties of pregnanolone emulsion are very similar to those of Althesin. Further studies will show whether it can fill the major vacuum left in anaesthetic practice after the withdrawal of Althesin.

The growth of crystals from molten salt solutions or “fluxes” has historically been an empirical art which developed principally as a tool for mineral synthesis. The use of fluxes to grow crystals of technological interest began with the work of Remeika who grew barium titanate, BaTiO3, from molten potassium fluoride, KF [1], and ferrimagnetic spinels, MFe2O4, from molten lead oxide, PbO [2]. A major impetus to flux growth was the discovery that magnetic garnets, Ln3Fe5O12, could be grown from PbO [3], Bi2O3 [3], and PbO-PbF2 mixtures [4]. That work and Remeika’s discovery of the addition of boric oxide to PbO and Bi2O3 to improve their solvent power for the growth of many oxides set the stage for wide application of the flux method.

The current methods of preparation of high quality magnetic garnet epitaxial films for bubble domain devices will be presented. This will include the Czochralski growth of defect free gallium garnet substrate crystals through optimizing the conditions of growth, especially the crystal rotation rate, the pulling rate and the oxygen over pressure. Methods of processing substrate wafers which have low surface defect densities will be described. The current status of the two methods of film deposition, liquid phase epitaxy and chemical vapor deposition, will be discussed with emphasis on the control of magnetic parameters such as moment, anisotropy, coercivity and domain mobility by adjustment of growth conditions and film composition.

The effects of growth conditions on the magnetic properties of substituted rare‐earth iron garnets grown by liquid phase epitaxy are discussed. Particular emphasis is placed on the influence of growth rate, growth temperature and growth procedure on the relevant magnetic properties of epitaxial garnet films.Data showing growth rate as a function of rotation rate and the degree of supersaturation are presented. The relationship between growth temperature and the magnitude of growth induced uniaxial magnetic anisotropy for the compositions Y2.40Eu0.60Ga1.1Fe3.9O12 and EuEr2Ga0.7Fe4.3O12 are given. The effects of melt composition on growth temperature are shown as the relevant compositional ratios in the melt are varied. The effect of spontaneous homogeneous nucleation during film growth is shown in relation to the magnetic properties of the films. The distribution coefficient of gallium as a function of temperature is presented along with data indicating the relationship between lead incorporation and growt...

A pilot line for the production of large high quality ZnO single crystals was established and many large crystals were produced. The pilot line can be divided into two units, (1) a molten salt line for the production of seed plates to be used in (2) the hydrothermal crystal growth pilot line. The design and construction of both lines were successfully completed and functioned as planned. The molten salt crystal growth effort was not as successful as had been anticipated. Large area, high quality crystals could not be made reproducibly by this technique. The most apparent reasons for the failure to do so rests in thermal gradient control during the growth cycle and/or the presence of impurities. Although these problems were not completely resolved the molten salt pilot line did yield sufficient plates for the initial portion of the hydrothermal pilot line, and hydrothermally grown crystals were sectioned and used as seeds for subsequent runs. The area of the crystals were increased by continued growth until large high quality crystals weighting more than 150 grams could be grown on such seeds within reasonable operating times.

Unexpectedly rapid oxygen diffusion has been observed at 25–250 °C in YIG films with uncompensated Ca additions of 0.1 to 0.23 atoms per formula unit. A 3‐μm‐thick film originally dark and conducting due to Fe4+ lightened and became insulating in 15 min at 100 °C in a reducing saturated solution of FeCl2. A diffusion distance of ∼0.5 mm has been observed along a film in 25 h at 250 °C. A model is proposed based on the dependence of the diffusion coefficient D on oxygen vacancy concentration. A magnetic bubble garnet film containing Ca, which also lightened at 250 °C, showed no observable changes in the pertinent bubble parameters.

Single crystals of magnetic garnets have been grown from solutions of molten lead oxied, iron oxide, and the oxides of yttrium, samarium, erbium, or gadolinium. The crystals are grown by slowly cooling melts from 1325°C to near 900°C. A convenient composition is 52.5 mole % PbO, 44 mole % Fe2O3, and 3.5 mole % M2O3 where M is Y, Gd, Er, or Sm. Crystals of yttrium‐iron garnet have been grown which contain gallium partially substituted for iron.The method may also be extended to the growth of nonmagnetic yttrium gallium garnets by using a melt which is 72.7 mole % PbO, 26 mole % Ga2O3 and 1.3 mole % Y2O3.Bismuth oxide can be used as a solvent for the growth of magnetic garnet crystals but the substitution of bismuth in the garnet lattice makes it less desirable than lead oxide.

From a batch of lithium‐rich highly ordered single crystals of lithium ferrite, a group of 13 spheres were prepared using regions selected for low defect concentrations. Linewidths measured at 5.1 GHz and ∼300°K ranged from 0.87 to 2.06 Oe with a mean value of 1.35 Oe. The resistivity of the crystals was 3 Ω·cm and 4πMs was 3720±50 G. The narrow linewidths in the presence of such high conductivity suggests a conductivity mechanism other than the usual one involving Fe2+ ions.The sphere with the lowest ΔH was used to measure the temperature dependence of ΔH, ΔHk→0 and HA[111] between 4.2° and 300°K at 10.4 GHz. The ΔH ranged from 1.45 Oe at 300°K to 0.55 Oe at 4.2°K with a peak of 2 Oe near 30°K. At 250°K, ΔHk→0 was 0.4 Oe. It exhibited a peak near 30°K (whose maximum was not measured) and was only 0.06 Oe at 4.2°K. The anisotropy field HA[111] decreased monotonically from 625 G at 4.2°K to 390 G at 300°K.The possession of samples having very small linewidths permitted the study of the effect of ordering o...

Large single crystals of yttrium and rare earth iron garnets, and yttrium and rare earth gallium garnets, have been grown from molten solutions of lead oxide and lead fluoride. The crystals are grown by slowly cooling melts from about 1260°C to near 950°C. Sample compositions are: for YIG, 8 mole % Y2O3, 22 mole % Fe2O3, 30 mole % PbO and 40 mole % PbF2; for YGaG, 5.8 mole % Y2O3, 14 mole % Ga2O3, 39.4 mole % PbO and 40.8 mole % PbF2.This method provides crystals both large in size and of superior quality. Best results are obtained when the containing crucible is hotter near its top than at its base since nucleation is thereby reduced.

Ferrimagnetic resonance linewidths as low as 2.6 oe can be obtained in lithium ferrite spheres at room temperature and 5 kMc by a series of treatments including polishing, heat treatment at 800°C, addition of lithium, and ordering. There exist optimum times of processing for each crystal. Freshly grown crystals show unusual variations in linewidth with processing, and this behavior is tentatively explained on the basis of strains in the crystal and nonuniformity of lithium content within the spherical sample.

Mossbauer effect (ME) measurements of the hyperfine (hf) interaction in single crystals of FeBO3, have been used to study the behavior of the sublattice magnetization near the Neel temperature. The ME spectra show that the two nearly antiferromagnetic sublattice moments lie within the easy plane, in agreement with symmetry considerations for weak ferromagnets with calcite structure. From about 0.94≤T/TN≤0.9996 the hf field fits the equation H(T)=H0D(1‐T/TN)β with β=0.354±0.005, D=1.208±0.001 and TN=348.35°K to ±0.01°K precision and to ±0.2°K absolute accuracy.