Slow rotation of a sphere in a non-Newtonian fluid with or without suction or injection

The flow generated by the rotation of a sphere in an infinitely extending fluid has recently been studied by Goldshtik. The corresponding problem for non-Newtonian Reiner-Rivlin fluids has been studied by Datta. Bhatnagar and Rajeswari have studied the secondary flow between two concentric spheres rotating about an axis in the non-Newtonian fluids. This last investigation was further generalised by Rajeswari to include the effects of small radial suction or injection. In Part A of the present investigation, we have studied the secondary flow generated by the slow rotation of a single sphere in non-Newtonian fluid obeying the Rivlin-Ericksen constitutive equation. In Part B, the effects of small suction or injection have been studied which is applied in an arbitrary direction at the surface of the sphere. In the absence of suction or injection, the secondary flow for small values of the visco-elastic parameter is similar to that of Newtonian fluids with inclusion of inertia terms in the Oseen approximation. If this parameter exceeds Kc = 18R/219, whereR is the Reynolds number, the breaking of the flow field takes place into two domains, in one of which the stream lines form closed loops. For still higher values of this parameter, the complete reversal of the sense of the flow takes place. When suction or injection is included, the breaking of the flow persists under certain condition investigated in this paper. When this condition is broken, the breaking of the flow is obliterated.

Influence of the hydrogen bond on the N-H stretching frequencies in amino-acids

The spectra of glycine, its addition compounds and other amino-acids exhibit Raman lines in the region from 3250 cm.−1 to 2500 cm.−1 It has been shown that these lines cannot be assigned to N-H...O stretching vibrations, where the N atom has the covalency of three, but to N+-H...O stretching vibration where the N atom has the covalency of four. Using the data obtained with triglycine sulphate which has the largest number of N+-H...O bonds and whose H bond lengths are known, the correlation curve giving the relation between the N+-H...O stretching frequencies and the corresponding H bond lengths has been drawn. Using this correlation curve, the N+-H...O stretching frequencies appearing inα-glycine,γ-glycine, diglycine hydrochloride, diglycine hydrobromide,l-asparagine monohydrate anddl-alanine have been satisfactorily accounted for on the basis of the known hydrogen bond lengths in these substances.

4-(5-Phenyl-1,2,4-triazolo[3,4-a]isoquinolin--yl)benzonitrile

In the title molecule, C23H14N4, the triazoloisoquinoline ring system is nearly planar, with an r.m.s. deviation of 0.038 (2) angstrom and a maximum deviation of -0.030 (2) angstrom from the mean plane of the triazole ring C atom which is bonded to the benzene ring. The benzene and phenyl rings are twisted by 57.65 (8) and 53.60 (9)degrees, respectively, with respect to the mean plane of the triazoloisoquinoline ring system. In the crystal structure, molecules are linked by weak aromatic pi-pi interactions [centroid-centroid distance = 3.8074 (12) angstrom]. In addition, the crystal structure exhibits a nonclassical intermolecular C-H center dot center dot center dot N hydrogen bond.

Dislocation dynamics in alpha titanium Dynamique des dislocations dans le titane alphaVersetzungsdynamik in alpha-Titan

The activation area and activation enthalpy are determined as a function of stress and temperature for alpha titanium. The results indicated that plastic flow below about 700°K occurs by a single thermally activated mechanism. Activation area determined by differential-stress creep tests falls in the range 80−8b2 and does not systematically depend on the impurity content. The total activation enthalpy derived from the temperature and strain-rate dependence of flow stress is 1.15 eV. The experimental data support a lattice hardening mechanism as controlling the low-temperature deformation in alpha titanium.

Synthesis and identification of a new class of (S)-2,6-diamino-4,5,6,7-tetrahydrobenzo[d]thiazole derivatives as potent antileukemic agents

Benzothiazoles are multitarget agents with broad spectrum of biological activity. Among the antitumor agents discovered in recent years, the identification of various 2-(4-aminophenyl) benzothiazoles as potent and selective antitumor drugs against different cancer cell lines has stimulated remarkable interest. Some of the benzothiazoles are known to induce cell cycle arrest, activation of caspases and interaction with DNA molecule. Based on these interesting properties of benzothiazoles and to obtain new biologically active agents, a series of novel 4,5,6,7-tetrahydrobenzo[d]thiazole derivatives 5(a-i) were synthesized and evaluated for their efficacy as antileukemic agents in human leukemia cells (K562 and Reh). The chemical structures of the synthesized compounds were confirmed by H-1 NMR, LCMS and IR analysis. The cytotoxicity of these compounds were determined using trypan blue exclusion, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Results showed that, these compounds mediate a significant cytotoxic response to cancer cell lines tested. We found that the compounds having electron withdrawing groups at different positions of the phenyl ring of the thiourea moiety displayed significant cytotoxic effect with IC50 value less than 60 mu M. To rationalize the role of electron withdrawing group in the induction of cytotoxicity, we have chosen molecule 5g (IC50 similar to 15 mu M) which is having chloro substitution at ortho and para positions. Flow cytometric analysis of annexin V-FITC/ propidium iodide (PI) double staining and DNA fragmentation suggest that 5g can induce apoptosis.

Relationship Drivers in Provider - Consumer Relationships. Empirical Studies of Customer Loyalty Programs (första upplagan slutsåld / first edition sold out, 'print on demand' 60 €)

The study addressed a phenomenon that has become common marketing practice, customer loyalty programs. Although a common type of consumer relationship, there is limited knowledge of its nature. The purpose of the study was to create structured understanding of the nature of customer relationships from both the provider’s and the consumer’s viewpoints by studying relationship drivers and proposing the concept of relational motivation as a provider of a common framework for the analysis of these views. The theoretical exploration focused on reasons for engaging in customer relationships for both the consumer and the provider. The themes of buying behaviour, industrial and network marketing and relationship marketing, as well as the concepts of a customer relationship, customer loyalty, relationship conditions, relational benefits, bonds and commitment were explored and combined in a new way. Concepts from the study of business-to-business relationships were brought over and their power in explaining the nature of consumer relationships examined. The study provided a comprehensive picture of loyalty programs, which is an important contribution to the academic as well as the managerial discussions. The consumer study provided deep insights into the nature of customer relationships. The study provides a new frame of reference to support the existing concepts of loyalty and commitment with the introduction of the relationship driver and relational motivation concepts. The result is a novel view of the nature of customer relationships that creates new understanding of the forces leading to loyal behaviour and commitment. The study concludes with managerial implications.

Understanding Customer Loyalty and Disloyalty The Effect of Loyalty-Supporting and -Repressing Factors (first edition sold out, 'print on demand' 60 €)

Customer loyalty has been a central topic of both marketing theory and practice for several decades. Customer disloyalty, or relationship ending, has received much less attention. Despite the close relation between customer loyalty and disloyalty, they have rarely been addressed in the same study. The thesis bridges this gap by focusing on both loyal and disloyal customers and the factors characterising them. Based on a qualitative study of loyal and disloyal bank customers in the Finnish retail banking market, both factors that are common to the groups and factors that differentiate between them are identified. A conceptual framework of factors that affect customer loyalty or disloyalty is developed and used to analyse the empirical data. According to the framework, customers’ loyalty status (behavioural and attitudinal loyalty) is influenced by positive, loyalty-supporting, and negative, loyalty-repressing factors. Loyalty-supporting factors either promote customer dedication, making the customer want to remain loyal, or act as constraints, hindering the customer from switching. Among the loyalty-repressing factors it is especially important to identify those that act as triggers of disloyal behaviour, making customers switch service providers. The framework further suggests that by identifying the sources of loyalty-supporting and -repressing factors (the environment, the provider, the customer, the provider-customer interaction, or the core service) one can determine which factors are within the control of the service provider. Attitudinal loyalty is approached through a customer’s “feeling of loyalty”, as described by customers both orally and graphically. By combining the graphs with behavioural loyalty, seven customer groups are identified: Stable Loyals, Rescued Loyals, Loyals at Risk, Positive Disloyals, Healing Disloyals, Fading Disloyals, and Abrupt Disloyals. The framework and models of the thesis can be used to analyse factors that affect customer loyalty and disloyalty in different service contexts. Since the empirical study was carried out in a retail bank setting, the thesis has managerial relevance especially for banks. Christina Nordman is associated with CERS, Center for Relationship Marketing and Service Management at the Swedish School of Economics and Business Administration. The doctoral thesis is part of the Göran Collert Research Project in Customer Relationships and Retail Banking and has been funded by The Göran Collert Foundation.

Starburst in the ultraluminous galaxy Arp 220: Constraints from observations of radio recombination lines and continuum

We present observations of radio recombination lines (RRL) from the starburst galaxy Arp 220 at 8.1 GHz (H92 alpha) and 1.4 GHz (H167 alpha and H165 alpha) and at 84 GHz (H42 alpha), 96 GHz (H40 alpha) and 207 GHz (H31 alpha) using the Very Large Array and the IRAM 30 m telescope, respectively. RRLs were detected at all the frequencies except 1.4 GHz, where a sensitive upper limit was obtained. We also present continuum flux measurements at these frequencies as well as at 327 MHz made with the VLA. The continuum spectrum, which has a spectral index alpha similar to -0.6 (S-nu proportional to nu(alpha)) between 5 and 10 GHz, shows a break near 1.5 GHz, a prominent turnover below 500 MHz, and a flatter spectral index above 50 GHz. We show that a model with three components of ionized gas with different densities and area covering factors can consistently explain both RRL and continuum data. The total mass of ionized gas in the three components is 3.2 x 10(7) M., requiring 3 x 10(5) O5 stars with a total Lyman continuum production rate N-Lyc similar to 1.3 x 10(55) photons s(-1). The ratio of the expected to observed Br alpha and Br gamma fluxes implies a dust extinction A(V) similar to 45 mag. The derived Lyman continuum photon production rate implies a continuous star formation rate (SFR) averaged over the lifetime of OB stars of similar to 240 M yr(-1). The Lyman continuum photon Production rate of similar to 3% associated with the high-density H II regions implies a similar SFR at recent epochs (t < 10(5) yr). An alternative model of high-density gas, which cannot be excluded on the basis of the available data, predicts 10 times higher SFR at recent epochs. If confirmed, this model implies that star formation in Arp 220 consists of multiple starbursts of very high SFR (few times 10(3) M. yr(-1)) and short duration (similar to 10(5) yr). The similarity of IR excess, L-IR/L-Ly alpha similar to 24, in Arp 220 to values observed in starburst galaxies shows that most of the high luminosity of Arp 220 is due to the ongoing starburst rather than to a hidden active galactic nucleus (AGN). A comparison of the IR excesses in Arp 220, the Galaxy, and M33 indicates that the starburst in Arp 220 has an initial mass function that is similar to that in normal galaxies and has a duration longer than 107 yr. If there was no infall of gas during this period, then the star formation efficiency (SFE) in Arp 220 is similar to 50%. The high SFR and SFE in Arp 220 is consistent with their known dependences on mass and density of gas in star-forming regions of normal galaxies.

Growth and characterization of germanium nanowires by electron beam evaporation

Germanium nanowires were grown on Au coated Si substrates at 380 degrees C in a high vacuum (5 x 10(-5) Torr) by e-beam evaporation of Germanium (Ge). The morphology observation by a field emission scanning electron microscope (FESEM) shows that the grown nanowires are randomly oriented with an average length and diameter of 600 nm and 120 nm respectively for a deposition time of 60 min. The nanowire growth ratewas measured to be similar to 10 nm/min. Transmission electron microscope (TEM) studies revealed that the Ge nanowires were single crystalline in nature and further energy dispersive X-ray analysis(EDAX) has shown that the tip of the grown nanowires was capped with Au nanoparticles, this shows that the growth of the Ge nanowires occurs by the vapour liquid solid (VLS) mechanism. HRTEM studies on the grown Ge nanowire show that they are single crystalline in nature and the growth direction was identified to be along [110]. (C) 2010 Elsevier B.V. All rights reserved.

Dielectric properties of barium magnesiotitanate ceramics, BaMg6Ti6O19

Phase-pure samples of barium magnesiotitanate, BaMg6Ti6O19 (BMT) are prepared by the wet chemical `gel-carbonate' method wherein the formation of BMT is complete below 950 degrees C as a result of the reaction between nanoparticles of BaCO3, MgO and TiO2. BMT powders are sintered at 1350-1450 C to dense ceramics. Extensive melting is noticed when the bulk composition falls between 0.4MgTiO(3)+0.6BaTiO(3)) and (0.6MgTiO(3)+0.4BaTiO(3)) along the MgTiO3-BaTiO3 tie-line in BaO-MgO-TiO2, phase diagram. Dielectric properties of sintered (BMT) ceramics have been investigated which showed epsilon similar or equal to 39 at 2 GHz, quality factor Q >= 10,000 and positive temperature coefficient of dielectric constant around 370 ppm degrees C-1.

Creep Behaviour of AE42 Magnesium Alloy and Its Composites Using Impression Creep Technique

The creep behaviour of a creep-resistant AE42 magnesium alloy has been examined in the temperature range of 150 to 240 degrees C at the stress levels ranging from 40 to 120 MPa using impression creep technique. A normal creep behaviour, i.e., strain rate decreasing with strain and then reaching a steady state, is observed at all the temperatures and stresses employed The stress exponent varies from 5.1 to 5.7 and the apparent activation energy varies from 130 to 140 kJ/mol, which suggests the high temperature climb of dislocation controlled by lattice self-diffusion being the dominant creep mechanism in the stress and temperature range employed The creep behaviour of the AE42 alloy has also been compared with its composites reinforced with Saffil short fibres and SiC particles in four combinations. All the composites exhibited a lower creep rate than the monolithic AE42 alloy tested at the same temperature and stress levels and the decrease in creep rate was greater in the longitudinal direction than in the transverse direction, as expected. All the hybrid composites, i.e., the composites reinforced with a combination of Saffil short fibres and SiC particles, exhibited creep rates comparable to the composite reinforced with 20% Saffil short fibres alone at all the temperature and stress levels employed, which is beneficial from the commercial point of view.

Electron-Paramagnetic-Res study of LiKSO4 in phase IV below -138 degrees C

A detailed single-crystal EPR study of phase IV of lithium potassium sulphate below -138 degrees C has been carried out using NH3+, which substitutes for K+, as the paramagnetic probe. The spin-Hamiltonian parameters have been evaluated at -140 degrees C and yield an isotropic g=2.0034; (AH)XX=(AH)YY=25.3 G and (AH)ZZ=23.8 G; (AN)XX=8.1 G, (AN)YY=21.2 G and (AN)ZZ=25.9 G. In this phase there are 12 magnetically inequivalent K+ sites and their occurrence is ascribed to the loss of a c glide.

Effect of La modification on antiferroelectricity and dielectric phase transition in sol-gel grown PbZrO3 thin films

Antiferroelectricity of sol-gel grown pure and La modified PbZrO3 thin films, with a maximum extent of 6 mol%, has been characterized by temperature dependent P-E hysteresis loops within the applied electric field of 60 MV/m. It has been seen that on extent of La modification electric field induced phase transformation can be altered and at 40 degrees C its maximum value has been observed at +/- 38 MV/m on 6 mol% modifications whereas the minimum value is +/- 22 MV/m on 1 mol%. On La modification the variation of electric field induced phase transformations at 40 degrees C has been correlated with the temperature of ntiferroelectric phase condensation on cooling. The critical electric fields for saturated P-E hysteresis loops have been defined from field dependent maximum polarizations and their variations on La modification show a similar trend as found in their dielectric phase transition temperatures. (C) 2010 Elsevier Ltd. All rights reserved.