Education in sustainable production in US universities

The evolution and current status of sustainable production education (SPE) in the United States is reviewed, both as a discrete entity and as an intersection of multiple disciplines. This paper (a) examines the current array of compatible and conflicting theories that guide the alternative approaches to SPE, (b) reviews the wide array of applications to which such theories and associated methodologies have been applied, and (c) presents a case study of the emerging interdisciplinary approach to SPE at Purdue University in West Lafayette, Indiana, USA, and its network of national and international collaborators. North Atlantic Treaty Organization (NATO) Committee on the Challenges to Modern Society (CCMS). Pilot study on clean products and processes Annual meeting, May 2–6, 2004, Budapest, Hungary

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Aging in velocity autocorrelations in granular gas of viscoelastic particles in two dimensions

We use large-scale molecular dynamics simulations to study aging of the velocity autocorrelation function of a force-free granular gas consisting of viscoelastic particles. We study the velocity autocorrelation function for a simplified model where the coefficient of restitution is constant for all collisions, but depends on current temperature of granular gas, it is called quasi-constant coefficient of restitution ε_eff. From our simulation results, it is observed that A(τ_w, τ) depends independently on both τ and τ_w. Initially, A(τ_w, τ) decays exponentially but later as τ_w increases, A(τ_w, τ) decays slowly due to emergence of correlations in velocity field. The explicit dependence of A(τ_w, τ) on τ_w implies that the system exhibits aging property.     

Bose-Einstein Condensation in Liquid 4He in Vycor

We present neutron scattering measurements of Bose-Einstein condensation (BEC) in liquid ⁴He confined in Vycor. The data show clear evidence of a condensate in Vycor with a condensate fraction comparable to that of bulk superfluid ⁴He, approximately 7.5% at low temperature and SVP. The temperature dependence of n₀(T) is also similar to that in the bulk with critical temperature for BEC, T_BEC, in the range 1.80BEC<2.05 K. The data are not accurate enough to show whether T_BEC for Vycor is the same or greater than the depressed critical temperature for superfluidity, T_c=1.95 K.     

Losses in diamond in the millimeter range

A theoretical and experimental investigation is made of the magnitude and nature of the dielectric losses in weakly absorbing synthetic diamonds in the wavelength range 1.75–6.8 mm at temperatures T=20–500 °C. Some samples exhibited extremely low losses (tan δ <10⁻⁵) which makes plasma-chemically deposited diamond wafers suitable for fabricating windows for megawatt continuous gyrotrons. It is shown that in principle, a further substantial reduction in losses can be achieved. Pis’ma Zh. Tekh. Fiz. 25, 85–89 (April 12, 1999)     

International Co-operation in Science and in Social Sciences as Reflected in Multinational Papers Indexed in SCI and SSCI

The paper presents a comparative analysis of publications, co-authored by Polish and foreign researchers, selected from seven annual files ofScience Citation Index and Social Sciences Citation Index (CD-ROM Editions 1992–1998). Information obtained from SCI and SSCI were elaborated, completed, coded and entered in two “international files” designed for analytical purposes. It was found that the number of internationally co-authored papers was many times higher (18982 records) in science than in social sciences (342 records). The share of these “international papers” in the “Polish files” increased in the time under review, but for those derived from SCI was also higher (39.1 – 46.0%) than in case of SSCI (22.4 – 37.0%). Results of the analysis include countries of foreign partners and affiliation of domestic co-authors, as well as, subject structure of both international files. Observed differences in the scale of international co-operation in science and in social sciences are being the matter under discussion. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date.     

Crack growth in structural adhesive joints in aqueous environments

The adhesive fracture energy, G _c , of metallic joints, bonded with a rubber-toughened epoxy adhesive, has been measured using monotonically-loaded tests. Such tests have been conducted in various relative humidities and in water, at 21 °C. Two surface pretreatments have been employed for the substrates prior to bonding: a simple grit-blast and degrease (‘GBD’) pretreatment or a grit-blast, degrease and silane primer (‘GBS’) pretreatment. The joints were formed using metallic substrates which were either (a) aluminium-alloy substrates, (b) steel substrates, or (c) ‘dissimilar’ substrates (i.e. one substrate being aluminium-alloy with the other one being steel). For both test environments, when G _c was plotted against the crack velocity, three regions of fracture behaviour could be distinguished. At low rates of displacement the crack grew in a stable manner, visually along the interface, and relatively low crack velocities could be readily measured. This was termed ‘Region I’ and here the value of G _c measured in the aqueous environment was relatively low compared to that measured in a relatively dry environment of 55% relative humidity. On the other hand, at relatively high rates of displacement the crack always grew in a stick-slip manner mainly cohesively in the adhesive layer at approximately 20 km/min. This was termed ‘Region III’, and here the value of G _c was relatively high and independent of the environmental test conditions employed. In this region the crack was considered to grow faster than the water molecules were able to reach the crack tip, which explains the independence of G _c upon the test environment. In between ‘Region I’ and ‘Region III’, a transition region was observed which was designated as ‘Region II’. The major effect of the ‘GBS’ pretreatment, compared to the ‘GBD’ pretreatment, was to increase the value of G _c both in ‘Regions I and III’, although the presence of the silane primer had the far greater effect in ‘Region I’.     

Feshbach Shape Resonance in Multiband Superconductivity in Heterostructures

We report experimental data showing the Feshbach shape resonance in the electron doped MgB₂ where the chemical potential is tuned by Al, Sc, and C substitutions. The scaling of the critical temperature T _c as a function of the Lifshitz parameter z = E _Γ−E _F, where E _F is the chemical potential and E _Γ is the energy of the Γ critical point where the σ Fermi surface changes from the 3D to a 2D topology, is reported. The resonant amplification of T _c(z) driven by the interband pairing is assigned to a Feshbach shape resonance characterized by quantum superposition of pairs in states corresponding to different spatial location and different parity. It is centered at z = 0 where the chemical potential is tuned to a Van Hove-Lifshits feature for the change of Fermi surface dimensionality in the electronic energy spectrum in one of the subbands. In this heterostructure at atomic limit the multiband superconductivity is in the clean limit because the disparity and negligible overlap between electron wavefunctions in different subbands suppresses the single electron interband impurity scattering rate. The emerging scenario from these experimental data suggests that the Feshbach shape resonance could be the mechanism for high T _c in particular nanostructured architectures.     

Solubility of lanthanum in strontium titanate in oxygen-rich atmospheres

Perovskite (ABO₃)-type lanthanum substituted strontium titanate ceramics (lanthanum content x), which had been sintered in pure oxygen at 1400 °C, were investigated from x = 0 up to x = 0.6 by light optical and scanning electron microscopic means in conjunction with X-ray analysis, X-ray diffraction, and pyconometry in order to determine the mechanism being responsible for the compensation of the electronic excess charge resulting from the "donor" lanthanum. A pure strontium vacancy compensation mechanism was observed for lanthanum contents up to x = 0.3. Above x = 0.4 titanium vacancies occur additionally but their concentration remains negligible compared to the predominating strontium vacancies. No indication of a solubility limit of lanthanum at x = 0.4, as stated in former works was observed. At x = 0.5 and 0.6 the lattice structure was found to be slightly distorted, tetragonally and orthorhombically, respectively. The lattice parameter obeys Vegard’s law up to the end member La_2/3□_1/3TiO₃ (□: vacant site). These results were completely confirmed by pycnometry data. This revised version was published online in November 2006 with corrections to the Cover Date.     

Kinematical transformations in amorphous selenium alloys used in xerography

Differential scanning calorimetric (DSC) studies were carried out on xerographic photoreceptor materials of amorphous selenium (a-Se), a-Se_1&#x2203-xTe_x and a-Se:0.5 wt% As alloys with various amounts of chlorine doping. Glass transformation kinetics of bulk and vapour-deposited film samples were essentially identical indicating a similar amorphous structure for both forms. The glass transition temperature,T _g, in the a-Se_1&#x2203-xTe_xsystem was found to increase monotonically with the tellurium content up to 13 wt% which was accompanied by a fall in the activation energy,E _gl, for the structural relaxation. 0.5wt% As increasedT _g, whereas chlorine doping in the amounts used (100 ppm) had no effect onT _g. Crystallization exotherms were analysed using the Kissinger method which was shown to remain a valid analysis by integrating the fundamental Kolmogoroff equation describing crystallization transformations by nucleation and growth. The signifiance of the activation energy,E _A, and the frequency factor,C ₀, in the Kissinger analysis is discussed and used in interpreting the different crystallization behaviour exhibited by the various alloys. The apparent activation energy,E _A, of the crystallization kinetics was found to fall with the temperature range accessed in the DSC experiment. When other authors' previous crystallization studies by other methods were also considered, then 1/E _A was found to fall nearly linearly with the mean reciprocal temperature, 1/T, used in the experiment. It is argued that this behaviour arises if the crystal growth rate scales with the inverse viscosity of the melt and the latter is described by a Vogel-Tammann-Fulcher type of behaviour. The additives tellurium and arsenic retard the crystallization essentially by increasing the viscosity. Chlorine doping was also found to have an inhibitory effect but due probably to a change in the nucleation kinetics, rather than a viscosity rise.     

The parameters of nonequilibrium microwave discharge in nitrogen in a tube in a rectangular waveguide

Computer codes are developed for the processing of emission spectra of nonequilibrium plasma in nitrogen for the purpose of obtaining information about the translational T _g and rotational T _rot temperatures, the populations of vibrational levels in the ground electron and electron-excited states, the electron energy distribution function, the electron concentration N _e , and the electric field intensity E. The computer codes are used to determine the parameters of microwave-discharge plasma in nitrogen in discharge systems of two types, namely, in a discharge tube (with a radius of 1 cm), which crosses a rectangular waveguide (plasmatron on the H ₁₀ wavelength, at a pressure of 1.7 torr and absorbed power density of 1.5 W/cm³), and in a discharge section of similar structure on the basis of prismatic resonator (at a pressure of 1.0 torr and absorbed power density of 0.4 W/cm³). The mechanisms of population of the N₂(C ³Π_u) state are treated.     

Phase control in coherent population distribution in molecules

A chirped laser pulse transfers population from one level to another level accessible by one photon dipole transition. We have used a pair of phase-locked chirped pulses of same frequency instead of a single chirped pulse to achieve phase control over the population transfer and thus creating coherent population distribution in hydrogen molecule. Simultaneous actions of the phase controlled interference and rapid adiabatic passages due to chirped pulses lead to the control in population transfer from the ground X(v = 0, j = 0) level to the C(v = 2, j = 1) level. We have extended this two-level system to a three-level 1 + 1 ladder system for population transfer from the X level to the J(v = 2, j = 2) level via the C intermediate level using two pairs of phase-locked laser chirped pulses and have achieved laudable control over the coherent population distribution.     

Trends in Russian research output in post-Soviet era

Recently, the Russian government has ordered evaluation and reform of the basic research system. As a consequence, the number of research staff at the Russian Academy of Sciences will be reduced by 20% by 2007. The basis for research evaluation and institute budgeting will be bibliometric indicators. In view of these changes we look at the Russian publication output and argue that

Heat transfer in forced convection in high-frequency electromagnetic fields

The effect of electromagnetic fields of frequency 3.85 · 10⁵ and 6.66 · 10⁵ Hz on heat transfer was investigated. The effect of the field depends on its strength and the fluid flow regime.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 28, No. 6, pp. 961–967, June, 1975.     

Microplasticity in Elgiloy

The room temperature microstrain characteristics of Elgiloy (composition in wt%, 40 Co, 20 Cr, 15 Ni, 7 Mo, 2 Mn, 0.1 C, balance Fe) have been determined for a range of microstructures corresponding to various alloy treatments reported previously. The friction stress was found to be constant ( _F=12±3 MN m^–2) for the solution treated (after prestrain), cold-worked and cold-worked plus aged at 500° C conditions, but decreased to _f=5±3 MN m^–2 after ageing at 800° C. The microscopic yield stress (MYS) increased with cold-working and subsequent ageing at 500° C to a maximum value of 210 MN m^–2 reflecting the increase in the long range internal stress field. An increase in the MYS of the solution treated strip was noted with ageing at 800° C, whereas the MYS of the cold-worked samples was decreased by this treatment. The solution treated and aged at 800° C samples exhibited a two-stage stress-plastic microstrain curve, whereas the cold-worked and cold-worked plus aged at 500° C conditions showed a three-stage stress-plastic microstrain behaviour.     

Some basic issues in dynamic crack growth in elastic-plastic solids

Differential equations for the asymptotic solution of the near-tip fields in the problem of steady rectilinear crack growth in elastic-plastic solids, are examined in a systematic manner. Two classes of elastoplastic materials are considered and the corresponding solutions are obtained and compared. The first class is the usual J ₂ -plasticity, with a smooth yield surface and plastic strain rate normal to the yield surface and, hence, coaxial with the stress deviator. For the second class of materials we still use the J ₂ or the Mises yield surface, but allow for deviation from normality, in order to model the vertex structure of the yield surface common in ductile crystalline solids. It is shown that the basic differential equations which govern the near-tip strain and stress fields are essentially the same whether or not plastic normality is imposed. This fact is discussed and its consequences are examined in some detail. It is shown that the near-field solution when the normality rule is imposed at the outset, is an isolated solution which cannot be obtained as a limiting case of the solutions with the yield surface tangential component of the plastic strain rate tending to zero. These latter solutions involve logarithmically singular strain fields and stress (but not strain) jump discontinuities, whereas the isolated solution does not have any singularities or discontinuities.Another issue considered in this work is the influence of the mode I loading on the mode II solution. While pure mode I and pure mode II problems admit clear-cut and distinct solutions, the presence of a small mode I component strongly dominates the asymptotic stress and strain fields and the corresponding solution at the crack tip.

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Résumé On examine de manière systématique diverses équations pour une solution asymptotique du champ près de l'extrémité d'une fissure, dans le cadre du problème de la croissance stable d'une fissure rectiligne dans des corps élasto-plastiques. On considère deux classes de matériaux élastoplastiques et on compare les solutions respectivement obtenues. La première classe correspond à une plasticité classique rendue par J ₂, avec une surface de glissements plastiques lisse, et un vecteur de vitesse de déformation plastique normal à la surface de glissement, et donc coaxial par rapport à la sollicitation. Pour la deuxième classe de matériaux, on utilise encore J ₂ ou une surface de glissements de Mises, mais on permet des déviations par rapport à la normale, de manière à représenter la strueture en vertex de la surface de glissements, qui est commune dans les solides cristallins ductiles. On montre que les équations différentielles de base qui régissent la déformation près de l'extrémité de la fissure et les champs de contraintes sont essentiellement les mêmes, qu'il y ait ou non imposition d'une normalité plastique. Cette constatation est discutée et ses conséquences sont examinées dans le détail. On montre que, lorsque la règle de normalité est de rigueur dès le départ, la solution du champ proche est une solution isolée qui ne peut se présenter comme le cas limite des solutions où la composante tangentielle à la surface des glissements du vecteur de vitesse de déformation plastique tendrait vers zéro. Ces dernières solutions comportent, en effet, des champs de déformations à singularité logarithmique, et des discontinuités en ressaut de la contrainte (et non de la déformation), tandis que la solution isolée ne présente ni singularités, ni discontinuités.Une autre question abordée dans cette étude est l'influence d'une sollicitation de mode I sur une solution propre au mode II. Si des problèmes qui relèvent purement d'un mode I ou d'un mode II admettent des solutions distinctes, la présence d'une légère composante de mode I peut influencer largement les champs asymptotiques de contraintes et de déformation, ainsi que les solutions correspondantes à l'extrémité de la fissure.

     

Process perspectives in international business research in CEE

Abstract

Internationalisation processes have been a core interest of international business research since the seminal contribution by Johanson and Vahlne (1977).

The unique context of economic transition in CEE directs the attention to dynamic aspects of these processes, and to the interaction with changing environmental conditions.

This introductory paper reviews the contributions of recent CEE research, and this special issue in particular, to advance our understanding of internationalisation processes.

     

Capsaicin pretreatment enhanced the bioavailability of fexofenadine in rats by P-glycoprotein modulation: in vitro,in situ and in vivo evaluation

Background and objective: Capsaicin is the main pungent principle present in chili peppers has been found to possess P-glycoprotein (P-gp) inhibition activity in vitro, which may have the potential to modulate bioavailability of P-gp substrates. Therefore, purpose of this study was to evaluate the effect of capsaicin on intestinal absorption and bioavailability of fexofenadine, a P-gp substrate in rats.

Methods: The mechanistic evaluation was determined by non-everted sac and intestinal perfusion studies to explore the intestinal absorption of fexofenadine. These results were confirmed by an in vivo pharmacokinetic study of oral administered fexofenadine in rats.

Results: The intestinal transport and apparent permeability (P_app) of fexofenadine were increased significantly by 2.8 and 2.6 fold, respectively, in ileum of capsaicin treated rats when compared to control group. Similarly, absorption rate constant (K_a), fraction absorbed (F_ab) and effective permeability (P_eff) of fexofenadine were increased significantly by 2.8, 2.9 and 3.4 fold, respectively, in ileum of rats pretreated with capsaicin when compared to control group. In addition, maximum plasma concentration (C_max) and area under the concentration-time curve (AUC) were increased significantly by 2.3 and 2.4 fold, respectively, in rats pretreated with capsaicin as compared to control group. Furthermore, obtained results in rats pretreated with capsaicin were comparable to verapamil (positive control) treated rats.

Conclusions: Capsaicin pretreatment significantly enhanced the intestinal absorption and bioavailability of fexofenadine in rats likely by inhibition of P-gp mediated cellular efflux, suggesting that the combined use of capsaicin with P-gp substrates may require close monitoring for potential drug interactions.     

Losses in superconducting cables in pulsed magnetic fields

Measurements have been carried out of superconducting cables of different types in pulsed magnetic fields. Three types of samples have been made from multifilamentary Nb_0.5  Ti_0.5 superconductors: one, a cluster of isolated wires; two, a double-layer twisted flat cable; and three, one-layer twisted tube samples. Dependences have been studied of ac losses on the amplitude, direction and change velocity of the magnetic field as well as on the diameter of filaments and twist pitch. It is shown that the ac losses in unsoldered samples are close to those in the cluster of isolated wires.