Flow Properties of Selected Pharmaceutical Powders from a Vibrating Spatula

Studies have been performed to characterize the flow of certain powders of pharmaceutical interest from a vibrating spatula. Lactose, cromolyn sodium, sodium chloride and charcoal powders were prepared by milling or sieving. Jet milling yielded micronized powder (1–10 μm), which was recovered from the product jar or metal cyclone. Particles in the larger size ranges were prepared by sieving. Photomicrograph images of the products were obtained by scanning electron microscopy. All of the powders were subjected to flow studies from vibrating beds to a top loading pan balance. Cumulative mass versus time, flow profiles were plotted. Bulk flow properties, as reflected in mass flow rates (M_i), were assessed. Irregular flow patterns were obtained for lactose, cromolyn sodium and charcoal, whereas sodium chloride was free flowing. The lengths of the lines depicting cumulative mass versus time, for samples of each material, were estimated using the inswing structured walk technique. Stride lengths (γ) of 1–100 mm were employed. Fractal dimensions were obtained from graphs of the logarithm of the cumulative mass versus time line length plotted against the logarithm of the stride length. Thus, flow irregularities were indicated by fractal dimensions (δ). In all of the powders studied, mass flow rates increased as the particle size increased. Sodium chloride did not exhibit fractal behavior (δ ≤ 1.007), as there were no flow irregularities. Lactose, cromolyn sodium and charcoal did not appear to exhibit fractal behavior (δ ≤ 1.010) at large stride lengths (γ = 15–100 mm). At small stride lengths (γ = 1–10 mm) these materials did exhibit fractal behavior (δ equals; 1.029–1.059) indicative of flow irregularity. This method may be used to numerically quantify uniformity of flow from a vibrating spatula, and would be useful in a number of industrial processes.     

Effects of adsorbates on electron spin polarization in low energy electron diffraction from tungsten (001): II. Ordered CO overlayer

Electron spin polarization and intensity profiles have been measured in low electron diffraction (LEED) for the (00) beam at θ = 13° and ø = 0° from a W(001) surface exposed to CO and annealed to obtain an ordered c(2 × 2) CO overlayer. The annealed surface with additional CO adsorbed was also studied. The polarization was found to be sensitive to the surface condition and the very distinct P?V profile corresponding to the c(2 × 2) overlayer is believed to be a very sensitive indicator of CO in the β₃ phase. The properties of the annealed surface exposed to further CO suggest the use of this surface as a low energy electron spin polarization analyzer.     

Al-Ti-V-M四元系合金TiAl3-VAl3-MAl3(M=Ni,Fe)赝三元系相图的室温截面

本文用X射线衍射法测定了Al-Ti-V-M四元系合金TiAl₃-VAl₃-MAI₃(M=Ni,Fe)两个赝三元系相图的室温截面。(1)TiAl₃-VAl₃NiAl₃赝三元系相图室温截面由一个单相点ε(NiAl₃)、一个单相区δ(TiAl₃和VAl₃形成的连续固溶体)和一个两相区δ+s所组成。(2)TiAl关键词：     

Thermodynamically nonequilibrium states in lanthanum manganite LaMnO3 doped with 5 at % Ba

Mössbauer spectroscopy and X-ray diffraction have been used to study structural transitions in the LaMnO_{3 + δ} compound doped with 5 at % Ba, annealed in vacuum, and cooled under different conditions: rapid cooling (quenching into liquid nitrogen), fast cooling, and slow cooling to room temperature. It has been shown experimentally that vacuum annealing and subsequent fast cooling result in the transition of the rhombohedral structure (δ > 0) of the synthesized compound to a mixture of three orthorhombic phases PnmaI, PnmaII, and PnmaII*, with stoichiometric composition in oxygen (δ = 0). Then, an unusual fluctuation change in the partial ratio of the phases is observed depending on the vacuum annealing time. The fluctuations disappear upon slow cooling and quenching of the sample.     

二乙酰分子内价轨道4ag+4bu的电子动量谱学研究

在高分辨率(ΔE=115eV, Δp≈01a.u.)电子动量谱仪上获得了二乙酰分子(d iacetyl)最内价轨道4ag_g+4bu_u的电离能谱和动量谱的实验结果， 并用Hartree-Fock和密度泛函理论方法做了理论计算.实验结果与理论计算符合较好. 关键词： 二乙酰 内价轨道 电离能 电子动量谱     

Spin polarization in low-energy electron diffraction: Surface analysis of Pt(111)

Transverse and longitudinal spin polarization components arising in the diffraction of unpolarized low-energy electrons from Pt(111) have been studied as functions of energy and diffraction geometry. Experimental data measured by means of a Mott detector are in good agreement with theoretical results obtained by relativistic LEED calculations. A detailed investigation of the selective sensitivity of the calculated polarization profiles to the surface relaxation δ₁₂ and to various non-structural model features firstly supports an ion-core potential involving an energy-dependent exchange approximation (by discriminating against two band structure potentials), and secondly establishes the geometry of Pt(111) as unreconstructed with a possible slight outward relaxation of the topmost atomic layer (δ₁₂ = 0.5% ± 1.0% of the bulk interlayer distance). A surface Debye temperature is found close to the bulk value 230 K.     

The FeH radical: rotational assignment of the a6A Δ(ν = 2) and b6II (ν = 1) levels

A dispersed fluorescence study of the FeH radical at near ambient (～450 K) temperature has identified the g⁶Φ-a ⁶δ (0, 2) and g⁶Φ-b⁶II (0, 1) bands in the orange region of the spectrum. The corresponding bands with upper state e⁶II are located at about 640nm in the red. High resolution measurements in LIF have enabled the assignment of around 275 lines to these four transitions. Analysis of these bands has provided a second vibrational interval for the a⁶δ state and a first vibrational interval for the b⁶II state as 1536cm^?1 and 1542cm^?1, respectively. Term values have also been measured for a set of levels with a tentative assignment to c⁴Φ_9/2 (ν = 1).     

Effect of electron irradiation on the oxidation of indium

The oxidation kinetics of indium is studied for two cases, namely, during continuous electron irradiation (E _p = 1800 eV) and without electron irradiation, as a function of the time of exposure to an oxygen medium at a partial oxygen pressure of 10⁻⁴ Pa and room temperature. The initial oxygen exposure was 50 L. The kinetic curves recorded upon continuous electron irradiation have two inflection points, and they can be attributed to the following three states of oxidation: physical adsorption, chemisorption with the formation of a nonstoichiometric oxide layer, and the growth of a homogeneous oxide layer. Only the first inflection point is observed during oxidation without electron irradiation, and further exposure does not lead to the second inflection point within the experimental time.     

Effect of surface plasmon oscillations on Auger electron emission

The integrated areas of the Al L₂₃VV and O KL₂₃L₂₃ Auger peaks and the Al surface plasmon energy ?ω_S are reported for the Al(001) surface as a function of exposure to O in the exposure range 0–114 L(1 L=1langmuir=10^?6Torr sec). It is shown that for exposures below a critical value of 15 L, ?ω_S is constant within experimental error while the O Auger peak area increases linearly. For exposures above 15 L, ?ω_S decreases linearly from 10.5 eV to 8.5 eV and the O Auger peak area undergoes relatively slow linear increases correspondingly. The Al Auger peak area decreases by 30% per 1 eV decrease of ?ω_S. The results are discussed with reference to theory relating Auger transition intensities to the spectral density function.     

The electron capture decay of 106mAg

The electron capture decay of 8.4d ^106mAg has been investigated by means of a 4π internal source scintillation spectrometer and a Ge(Li) detector. The L/K capture ratios to the 2952 and 2757 keV excited states of ¹⁰⁶Pd have been measured: (L/K)₂₉₅₂ = 0.203 ± 0.003 and (L/K)₂₇₅₇ = 0.1457 ± 0.0010. The value of Q = 3053 ± 3 keV has been deduced from these L/K ratios.     

Use of the 447 nm He I line to determine electron concentrations

The helium 447 nm complex line has been excited in a wall-stabilized arc fed at atmospheric pressure by pure He, He-H₂, He-Ne-H₂ or He-Ar-H₂ mixtures. Photoelectric endon observations of the central part of the arc channel were made with high spatial (1/600) and spectral (53,000) resolution.A collection of 88 helium 447 nm line profiles, of which 75 were recorded simultaneously with H_β and Ne I or Ar II line profiles, yielded information about the electron concentration (2 X 10²⁰-2 X 10²² m^-3), temperature and relative ion composition of the plasma. Plots have been made of the forbidden to allowed peak separations (S), forbidden to allowed relative intensities of the peaks (F/A) and dips (i.e. the minimum intensities between lines) to allowed peak intensities (D/A) as functions of electron concentration, temperature and ionic composition in different plasmas.The peak separations depend only on the electron concentration. Other characteristic line-profile parameters (F/A and D/A) show weak ion motion with a strong electron-concentration influence. We propose simple formulae, which may be useful for practical determinations of the electron concentrations in helium-containing plasmas with an accuracy of ±15% and without taking into account either the chemical composition of the plasma or the temperature.     

A comparative study of the dopant profiles in diffused planar optical waveguides by SIMS and guided wave probe

A technique has been developed for dopant concentration depth profiling using static Secondary Ion Mass Spectrometry (SIMS), and an ex-situ ion milling facility to produce “tapers” through the region of interest of an optical waveguide sample. Results have been obtained for titanium-diffused optical waveguides in lithium niobate and for potassium and caesium ion-exchanged glass waveguides. The SIMS profiles have been compared with refractive index profiles in multimode structures. The refractive index profiles have been obtained from the waveguide mode spectra by a piecewise linear Wentzel-Kramers-Brillouin (WKB) method. The two profiles are in close agreement. Use of the SIMS technique for single mode Ti∶LiNbO₃ waveguides has revealed significant changes in the forms of the profiles, compared with deeper structures, and we suggest a mechanism to account for these changes.     

Structure and dielectric properties of Bi6 − x Sr x Ti2 − x Nb2 + x O18 (x = 0–2) solid solutions

The structural and electrophysical characteristics of a series of solid solutions of layered perovs-kite-like oxides Bi_{6 ? x} Sr _x Ti_{2 ? x} Nb_{2 + x} O₁₈ (x = 0, 0.25, 0.5, 1.0, 1.5, 2.0) have been studied. The temperature dependences of the relative permittivity ?/?₀(T) and dielectric loss tangent tanδ have been measured. The dependences of the maximum of the permittivity ?/?₀, Curie temperature T _C, lattice parameters, and the unit cell volume on x have been obtained. The structural parameter a, which corresponds to the polar direction, and the value of the orthorhombic distortion of the unit cell have been found to demonstrate noticeable negative deviations from the Vegard’s law. It has been established that the variations of the orthorhombic distortion correlate with the variations of the permittivity maximum; however, they do not markedly influence the Curie temperature that varies linearly over entire range of changes in x.     

Angular dependence of auger electron emission from Cu (111) and (100) surfaces

Experimental angular emission profiles of the M_2,3M_4,5M_4,562 eV Cu Auger electrons from clean copper (100) and (111) surfaces in several azimuths are presented. A simple single scattering theory to account for elastic scattering of the Auger electrons by other ion cores in the solid is presented, and calculations have been performed to assess the importance of this process in contributing to the observed angular dependence. These calculations produce angular structure having a similar magnitude and temperature dependence to that observed experimentally, and some featural similarity in peak positions or shapes. It appears that elastic scattering is an important source of angular dependence, and that studies of adsorbed species on surfaces should provide a very sensitive method of surface structure determination.     

Experimental and theoretical investigations into the electronic structure of CF2Br2 by electron momentum spectroscopy

The binding energy spectra and electron momentum density distributions for the valence orbitals of CF₂Br₂ have been obtained by using electron momentum spectroscopy (EMS) at an impact energy of 1200 eV plus binding energy. The measured electron momentum profiles are compared with Hartree–Fock (HF) and density functional theory (DFT) calculations with different-sized basis sets. In general, the DFT-B3LYP calculation using the large basis sets of 6-311++G** and aug-cc-pVTZ fairly describe the experimental results. Moreover, the controversial orderings of the outer valence orbitals have been reassigned. The pole strength of the main ionization transition from the inner valence orbital of 1b₂ is determined.     

Growth of fullerene on Ag and hydrogen-passivated Si substrates: Effect of electron beam exposure on growth modes

We have used Auger electron spectroscopy (AES) to investigate the effect of electron beam exposure on growth modes of fullerene (C₆₀) on substrates like Ag and hydrogen-passivated Si(1 1 1). The electron beam comprises of 3.4 keV electrons, which are used in the AES study. To investigate the effect, Auger signal (AS) vs. deposition time (t) measurements were conducted in a sequential mode, i.e., alternating deposition of C₆₀ and analysis using the electron beam. Duration of AES data collection after each deposition was the duration of exposure to electron beam in this experiment. For the growth study of C₆₀ on Ag, three AS-t plots were recorded for three different durations of exposure to electron beam. Changes in the AS-t plot, depending on the duration of exposure to the electron beam, reflect the electron beam-induced damage. Electron beam-induced damages of C₆₀ produce carbon materials of different densities and consequently transmission coefficient (α) of Auger electron through this material changes. In order to fit the AES (AS vs. t) data a model has been used which simultaneously provides the growth mode and the transmission coefficient. Observation of an increasing transmission coefficient with the increasing duration of exposure to the electron beam from α=0.34 to 0.60 indicates the change of the nature of the carbon material due to the partial damage of C₆₀.     

Measurements of thermal electron attachment rate coefficients to molecules using an electron swarm technique

An existing electron swarm apparatus has been redesigned and upgraded. In particular, the new design incorporates a novel planar radioactive foil to form an integral part of the drift tube, allowing us to overcome inherent problems present in our earlier system which used a cylindrical radioactive source. In addition to this, substantial upgrades have been made to improve the gating and amplification electronics and the data acquisition system. This has resulted in a much greater signal to noise ratio and improved accuracy. This paper describes the upgraded apparatus and its use in obtaining thermal (300 K) attachment rate coefficients to a number of molecules. The quality of the measurements and data are illustrated through the measurement of the thermal attachment rate coefficient for SF₆ (k_th(SF₆) = (2.38 ±0.15 ) ×10 ^-7 cm³ s^-1). Thermal electron attachment rate coefficients for four other molecules are presented, namely for two derivatives of SF₆, SF₅CF₃ and SF₅Cl, and two perfluorocarbons, c-C₄F₈ and 2-C₄F₈.     

Mn2+doping-induced-effects on commensuration and incommensuration of potassium zinc chloride crystal

Undoped and Mn²⁺-doped with different concentrations of potassium zinc chloride (KZC) crystals were grown from aqueous solutions by slow evaporation. The dielectric constant (ε), dielectric losses (tan?δ) and ac conductivity (σ_ac) of the crystals in the ferroelectric-commensurate, incommensurate and normal phases have been measured as a function of frequency, in the range 1–100?kHz, and temperature, in the range 300–580?K. Virgin samples were subjected to measurements of the frequency dependence at selected temperatures and measurements of the temperature dependence was then followed using the same samples. The increase of ε with T could be due to a combination of conductivity, structural variations and discommensuration (DC) formation and pinning as well. The increase of tan?δ with temperature was attributed to relaxation loss in addition to conduction loss, which increases more rapidly with temperature. The ac conductivity (σ_ac) and tan?δ along the polar axis of KZC increased significantly with increasing Mn²⁺ content while ε decreased. σ_ac changed with frequency according to a power law of the form σ_ac?=?f? ^s where 0.15<s<1.27. A linear decrease of ε and tan?δ with increasing the frequency was also found. The obtained results were treated by considering the effect of Mn²⁺-doping on stripples nucleation, DC evolution/annihilation, DC-lattice formation and DCs pinning by the crystal lattice and/or structural defects for virgin and thermally treated samples.     

Time dependence of the luminescence intensity in CdI2-Cd and CdI2-Ag crystals

The decrease in the luminescence intensity (luminescence ??fatigue??) of long-wavelength emission bands with time in CdI₂-Cd (??_max = 700 nm) and CdI₂-Ag (??_max = 680 nm) crystals upon exposure to light in the fundamental absorption region has been studied. The process parameters, i.e., the capture cross section ?? and the fraction ?? of centers disappeared during interband irradiation, have been determined. The model of electronic processes has been proposed, within which experimental data have been consistently explained.     

Post-collision interaction in inner-shell ionisation of ArL 3 by electron impact

The shifts and shapes of ArL ₃ Auger lines due to the post-collision interaction (PCI) in the inner-shell ionisation of theL ₃-shell of argon by electron impact have been measured for the range of excess energiesE ₁=10 to 1,500 eV. The experimental shifts {ie67-01} could be fitted by a relation {ie67-02} withc=(5.3±0.4) andn= (?0.45±0.04) whereГ(ArL ₃)=130 meV is the ArL ₃-level width. In a classical model the PCI shifts have been calculated for two limiting cases:a) whereE ₁ is large enough (E ₁>50 eV) for the motion of the two slow electrons to be treated as uncorrelated, andb) forE ₁→0. The calculated shifts forE ₁=250, 750 and 1,750 eV are in good agreement with the experimental results. Also the calculated PCI distorted shapes of Auger lines for differentE ₁ agree reasonably with the experimental Auger line shapes.