Slip line field analysis of a simple plane strain closed‐die forging

A slip line field is proposed for symmetrical single‐cavity closed‐die forging by rough dies. A compatible velocity field is shown to exist. Experiments were conducted using lead workpiece and rough dies. Experimentally observed flow and load were used to validate the proposed slip line field. The slip line field was used to simulate the process in the computer with the objective of studying the influence of flash geometry on cavity filling.

Semi-similar solutions of the unsteady compressible second-order boundary layer flow at the stagnation point

Semi-similar solutions of the unsteady compressible laminar boundary layer flow over two-dimensional and axisymmetric bodies at the stagnation point with mass transfer are studied for all the second-order boundary layer effects when the free stream velocity varies arbitrarily with time. The set of partial differential equations governing the unsteady compressible second-order boundary layers representing all the effects are derived for the first time. These partial differential equations are solved numerically using an implicit finite-difference scheme. The results are obtained for two particular unsteady free stream velocity distributions: (a) an accelerating stream and (b) a fluctuating stream. It is observed that the total skin friction and heat transfer are strongly affected by the surface mass transfer and wall temperature. However, their variation with time is significant only for large times. The second-order boundary layer effects are found to be more pronounced in the case of no mass transfer or injection as compared to that for suction. Résumé Des solutions semi-similaires d'écoulement variable compressible de couche limite sur des corps bi-dimensionnels thermique, sont étudiées pour tous les effets de couche limite du second ordre, lorsque la vitesse de l'écoulement libre varie arbitrairement avec le temps. Le systéme d'équations aux dérivées partielles représentant tous les effets est écrit pour la premiére fois. On le résout numériquement á l'aide d'un schéma implicite aux différences finies. Les résultats sont obtenus pour deux cas de vitesse variable d'écoulement libre: (a) un écoulement accéléré et (b) un écoulement fluctuant. On observe que le frottement pariétal total et le transfert de chaleur sont fortement affectés par le transfert de masse et la température pariétaux. Néanmoins, leur variation avec le temps est sensible seulement pour des grandes durées. Les effets sont trouvés plus prononcés dans le cas de l'absence du transfert de masse ou de l'injection par rapport au cas de l'aspiration.

Isobaric electrical resistance along the critical line in nickel: An experimental test of universality

High-precision measurement of the electrical resistance of nickel along its critical line, a first attempt of this kind, as a function of pressure to 47.5 kbar is reported. Our analysis yields the values of the critical exponents α=α’=-0.115±0.005 and the amplitude ratios ‖A/A’‖=1.17±0.07 and ‖D/D’‖=1.2±0.1. These values are in close agreement with those predicted by renormalization-group (RG) theory. Moreover, this investigation provides an unambiguous experimental verification to one of the key consequences of RG theory that the critical exponents and amplitudes ratios are insensitive to pressure variation in nickel, a Heisenberg ferromagnet.

High-pressure NMR investigations of the protonic conductor (NH4)4Fe(CN)6.1.5H2O

The effect of high hydrostatic pressure up to 1.5 GPa on ionic motion in (NH4)4Fe(CN)6.1.5H2O has been studied by wide-line 1H NMR experiments performed in the temperature range from room temperature to 77 K. The experiments at room temperature have shown a large increase in the second moment at 0.45 GPa as a result of a pressure-induced phase transition. The temperature dependence study up to 0.425 GPa has shown a gradual increase in the values of activation energy and attempt frequency with increase in pressure. The activation volume for motion at 300 K has been estimated to be 6% of molar volume. Vacancy-assisted ionic jumps are concluded to be the mode of charge transport. Second moments estimated at 77 K show evidence for tunnelling reorientation of at least one of the two NH4+ groups in the compound.

Second-order boundary-layer effects for the unsteady laminar incompressible three-dimensional stagnation-point flow

All the second-order boundary-layer effects on the unsteady laminar incompressible flow at the stagnation-point of a three-dimensional body for both nodal and saddle point regions have been studied. It has been assumed that the free-stream velocity, wall temperature and mass transfer vary arbitrarily with time. The effect of the Prandtl number has been taken into account. The partial differential equations governing the flow have been derived for the first time and then solved numerically unsteady free-stream velocity distributions, the nature of the using an implicit finite-difference scheme. It is found that the stagnation point and the mass transfer strongly affect the skin friction and heat transfer whereas the effects of the Prandtl number and the variation of the wall temperature with time are only on the heat transfer. The skin friction due to the combined effects of first- and second-order boundary layers is less than the skin friction due to, the first-order boundary layers whereas the heat transfer has the opposite behaviour. Suction increases the skin friction and heat transfer but injection does the opposite

Transcriptional analysis of persistent Chlamydia pneumoniae infection in vitro

Chlamydia pneumoniae can cause acute respiratory infections including pneumonia. Repeated and persistent Chlamydia infections occur and persistent C. pneumoniae infection may have a role in the pathogenesis of atherosclerosis and coronary heart disease and may also contribute to the development of chronic inflammatory lung diseases like chronic obstructive pulmonary disease (COPD) and asthma. In this thesis in vitro models for persistent C. pneumonia infection were established in epithelial and monocyte/macrophage cell lines. Expression of host cell genes in the persistent C. pneumoniae infection model of epithelial cells was studied by microarray and RT-PCR. In the monocyte/macrophage infection model expression of selected C. pneumoniae genes were studied by RT-PCR and immunofluorescence microscopy. Chlamydia is able to modulate host cell gene expression and apoptosis of host cells, which may assist Chlamydia to evade the host cells' immune responses. This, in turn, may lead to extended survival of the organism inside epithelial cells and promote the development of persistent infection. To simulate persistent C. pneumoniae infection in vivo, we set up a persistent infection model exposing the HL cell cultures to IFN-gamma. When HL cell cultures were treated with moderate concentration of IFN-gamma, the replication of C. pneumoniae DNA was unaffected while differentiation into infectious elementary bodies (EB) was strongly inhibited. By transmission electron microscopy small atypical inclusions were identified in IFN-gamma treated cultures. No second cycle of infection was observed in cells exposed to IFN-gamma , whereas C. pneumoniae was able to undergo a second cycle of infection in unexposed HL cells. Although monocytic cells can naturally restrict chlamydial growth, IFN-gamma further reduced production of infectious C. pneumoniae in Mono Mac 6 cells. Under both studied conditions no second cycle of infection could be detected in monocytic cell line suggesting persistent infection in these cells. As a step toward understanding the role of host genes in the development and pathogenesis of persistent C. pneumoniae infection, modulation of host cell gene expression during IFN-gamma induced persistent infection was examined and compared to that seen during active C. pneumoniae infection or IFN-gamma treatment. Total RNA was collected at 6 to 150 h after infection of an epithelial cell line (HL) and analyzed by a cDNA array (available at that time) representing approximately 4000 human transcripts. In initial analysis 250 of the 4000 genes were identified as differentially expressed upon active and persistent chlamydial infection and IFN-gamma treatment. In persistent infection more potent up-regulation of many genes was observed in IFN-gamma induced persistent infection than in active infection or in IFN-gamma treated cell cultures. Also sustained up-regulation was observed for some genes. In addition, we could identify nine host cell genes whose transcription was specifically altered during the IFN-gamma induced persistent C. pneumoniae infection. Strongest up-regulation in persistent infection in relation to controls was identified for insulin like growth factor binding protein 6, interferon-stimulated protein 15 kDa, cyclin D1 and interleukin 7 receptor. These results suggest that during persistent infection, C. pneumoniae reprograms the host transcriptional machinery regulating a variety of cellular processes including adhesion, cell cycle regulation, growth and inflammatory response, all of which may play important roles in the pathogenesis of persistent C. pneumoniae infection. C. pneumoniae DNA can be detected in peripheral blood mononuclear cells indicating that the bacterium can also infect monocytic cells in vivo and thereby monocytes can assist the spread of infection from the lungs to other anatomical sites. Persistent infection established at these sites could promote inflammation and enhance pathology. Thus, the mononuclear cells are in a strategic position in the development of persistent infection. To investigate the intracellular replication and fate of C. pneumoniae in mononuclear cells we analyzed the transcription of 11 C. pneumoniae genes in Mono Mac 6 cells during infection by real time RT-PCR. Our results suggest that the transcriptional profile of the studied genes in monocytes is different from that seen in epithelial cells and that IFN-gamma has a less significant effect on C. pneumoniae transcription in monocytes. Furthermore, our study shows that type III secretion system (T3SS) related genes are transcribed and that Chlamydia possesses a functional T3SS during infection in monocytes. Since C. pneumoniae infection in monocytes has been implicated to have reduced antibiotic susceptibility, this creates opportunities for novel therapeutics targeting T3SS in the management of chlamydial infection in monocytes.

A New Structure Preserving Energy Function Incorporating Transmission Line Resistances

A novel method to account for the transmission line resistances in structure preserving energy functions (SPEF) is presented in this paper. The method exploits the equivalence of a lossy network having the same conductance to susceptance ratio for all its elements to a lossless network with a new set of power injections. The system equations and the energy function are developed using centre of inertia (COI) variables and the loads are modelled as arbitrary functions of respective bus voltages. The application of SPEF to direct transient stability evaluation is presented considering a realistic power system example.

Microfoundations of HRM effects: Individual and Collective Attitudes and Performance

Previous research on Human Resource Management (HRM) has focused extensively on the potential relationships between the use of HRM practices and organizational performance. Extant research in HRM has been based on the underlying assumption that HRM practices can enhance organizational performance through their impact on positive employee attitudes and performance, that is, employee reactions to HRM. At the current state of research however, it remains unclear how employees come to perceive and react to HRM practices and to what extent employees in organizations, units and teams react to such practices in similar or widely different ways. In fact, recent HRM studies indicate that employee reactions to HRM may be far less homogeneous than assumed. This raises the question of whether or not the linkage between HRM and organizational outcomes can be explained by employee reactions in terms of attitudes and performance, if these reactions are largely idiosyncratic. Accordingly, this thesis aims to shed light on the processes that shape individuals’ reactions to HRM practices and how these processes may influence the variance or sharedness in such reactions among employees in organizations, units and teams. By theoretically developing and empirically examining the effects of employee perceptions of HRM practices from the perspective of ‘HRM as signaling’ and psychological contract theory, the main contributions of this thesis focus on the following research questions: i) How employee perceptions of the HRM practices relate to individual and collective employee attitudes and performance. ii) How employee perceptions of HRM practices relates to variance in employee attitudes and performance. iii) How collective employee performance mediates the relationship between employee perceptions of HRM practices and organizational performance. Regarding the first research questions the findings indicate that individuals do respond positively to HRM practices by adjusting their felt obligations towards the employer. This finding is in line with the idea of HRM as a signaling device where each HRM practice, implicitly or explicitly, sends signals to employees about promised rewards (inducements) and behaviors (obligations) expected in return. The relationship was also confirmed at the group level of analysis. What is more, variance was found to play an important role in that employee groups with more similar perceptions about the HRM system displayed a stronger relationship between HRM and employee obligations. Concerning the second question the findings were somewhat contradictory in that a strong HRM system was found negatively related to variance in employee performance but not employee obligations. Regarding the third question, the findings confirmed linkages between the HRM system and organizational performance at the group level and the HRM system and employee performance at the individual level. Also, the entire chain of links from the HRM system through variance in employee performance, and further through the level of employee performance to organizational performance was significant.

On the elimination of DC in reconstructed wavefronts from in-line holograms

New experimental results to demonstrate that the annoying DC in the reconstructed wavefronts from in-line holograms could be successfully eliminated are presented in this paper. The complete elimination of DC has been achieved by making proper use of a Mach-Zehnder interferometer. The results for an in-line hololens and an in-line Fourier transform hologram are discussed.

2,1,3-Bentsoksadiatsolirakenteiset molekyylit antibakteerisina ja antiparasiittisina yhdisteinä

Aikaisemman tutkimuksen perusteella tiedettiin tiettyjen 2,1,3-bentsoksadiatsolirakenteisten molekyylien olevan aktiivisia Chlamydia pneumoniae –bakteeria vastaan. Tutkimusta lähdettiin jatkamaan ja 2,1,3-bentsoksadiatsolimolekyylien rakenne-aktiivisuusuhteista haluttiin saada lisätietoa. Tarkoituksena oli kehittää 2,1,3-bentsoksadiatsolimolekyyleille ja sen avulla muodostaa molekyylikirjasto. Syntetisoidut molekyylit haluttiin testata sekä Chlamydia pneumoniae -bakteeria että Leishmania donovani –parasiittia vastaan. Chlamydia pneumoniae –bakteeri aiheuttaa akuutteja ylä- ja alahengitystieinfektiota, kuten keuhkoputkentulehdusta. Akuutissa tulehduksessa oireet vaihtelevat huomattavasti. Chlamydia pneumoniae –bakteerilla on myös taipumus aiheuttaa kroonisia tulehduksia. Nämä ovat useissa tutkimuksissa yhdistetty kansantaloudellisesti merkittäviin sairauksiin, kuten ateroskleroosiin ja astmaan. Leishmanioosi on toiseksi yleisin loissairaus ihmisellä malarian jälkeen. Leishmania donovani –parasiitti voi aiheuttaa tappavaa viskeraalista leishmanioosia. Vuodessa leishmanioosiin kuolee yli 50 000 ihmistä. Viime vuosina leishmanioosin lääkehoidossa on esiintynyt monenlaisia ongelmia. Osat lääkkeistä ovat menettäneet tehonsa ja osalla esiintyy vakavia haittavaikutuksia. 2,1,3-Bentsoksadiatsolirakenteisille yhdisteille saatiin kehitettyä toimiva synteesireitti. Lähtöaineena käytettiin 4-amino-2-nitrobentsoehappoa, josta saatiin hapettavalla renkaansulkeutumisreaktiolla 2,1,3-bentsoksadiatsoli-5-karboksyylihappoa. Karboksyylihaposta syntetisoitiin amidi-välituotteen kautta 2,1,3-bentsoksadiatsoli-5-karbonitriiliä. Hydroksyyliamiini hydrokloridin avulla 2,1,3-bentsoksadiatsoli-5-karbonitriilistä muodostettiin vastaavaa karboksimidamidia, joka oli synteesireitin yhteinen välituote kaikille molekyyleille. Viimeisessä vaiheessa N´-hydroksidi-2,1,3-bentsoksadiatsoli-5-karboksimidamidin annettiin reagoida joko fenyyli-isosyanaatin tai fenyyli-isotiosyanaatin kanssa, jolloin saatiin lopputuotetta. Synteesireitin kehittäminen osoittautui haastavaksi ja loppujen lopuksi saatiin ainoastaan kolme lopputuotetta syntetisoitua. Yksi lopputuotteista testattiin C. pneumoniae –bakteeria vastaan Åbo akademissa Turussa. Testattavaa yhdiste ei sisältänyt 2,1,3-bentsoksadiatsoliarengasta ja bioaktiivisuuskokeen tulos oli odotusten mukainen. Yhdiste ei ollut aktiivinen C. pneumoniae –bakteeria vastaan alhaisilla konsentraatioilla ja tuloksesta voitiin todeta 2,1,3-bentsoksadiatsolirengaan olevan tärkeä aktiivisuuden kannalta. Kaksi lopputuotetta saatiin testaukseen Leishamania donovani –parasiittia vastaan Israeliin. Ainoastaan toinen molekyyleistä sisälsi 2,1,3-bentsoksadiatsolirakenteen. Bioaktiivisuuskokeiden tulokset olivat erittäin rohkaisevia. Yhdisteet olivat aktiivisia parasiittia vastaan jo alhaisilla konsentraatioilla. Kuitenkin 2,1,3-bentsoksadiatsolirakenteinen molekyyli oli aktiivisempi, joten tämäkin aktiivisuuskokeen perusteella huomattiin rengasrakenteen olevan tärkeä aktiivisuuden kannalta.

Investigations of the Nature of Critical Line Very Close to a Double Critical Point

The curvature of the line of critical points in a reentrant ternary mixture is determined by approaching the double critical point (DCP) extremely closely. The results establish the continuous and quadratic nature of this line. Out study encompasses as small a loop size (ΔT) as 663 mK. The DCP is realized when ΔT becomes zero.

Study of forging design using slip-line fields

The main purpose of forging design is to ensure cavity filling with minimum material wastage, minimum die load and minimum deformation energy. Given the desired shape of the component and the material to be forged, this goal is achieved by optimising the initial volume of the billet, the geometrical parameters of the die and the process parameters. It is general industrial practise to fix the initial billet volume and the die parameters using empirical relationships derived from practical experience. In this paper a basis for optimising some of the parameters for simple closed-die forging is proposed. Slip-line field solutions are used to predict the flow, the load and the energy in a simple two-dimensional closed-die forging operation. The influence of the design parameters; flash-land width, excess initial workpiece area and forged cross-sectional size; on complete cavity filling and efficient cavity filling are investigated. Using the latter as necessary requirements for forging, the levels of permissable design parameters are determined, the variation of these levels with the size of the cross-section then being examined.