The numerical prediction of flow and heat transfer in rod-bundle geometries

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Some remarks on a theorem of montgomery and vaughan

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Three-dimensional photoelastic study of the load-carrying capacity/face width ratio of Wildhaber-Novikov gears for automotive applications

Wildhaber-Novikov gears are becoming more and more popular for heavy load applications. They have been tried as speed-reducing gears, in spite of heavy noise generation, in aircraft jet engines, marine engines and agricultural machinery. These circular-arc gears, though stronger than involute geras, have the disadvantage of needing larger face width. Axial face width required can be minimized only at the expense of load-carrying capacity. This is not a serious disadvantage with stationary engines. But in the case of automotive applications, this fact limits the load-carrying capacity of Wildhaber-Novikov gears, since space problem is very critical in these applications and large face widths, therefore, cannot be used for such gear-reduction units. The face width is determined by the helix angle and, therefore, a thorough investigation of the dependence of the load-carrying capacity on helix angle is necessary, if these special types of gears have to make headway into the automotive field. In this experimental investigation, three-dimensional photoelastic technique has been employed to study the load-carrying capacity/face width ratio. Three-dimensional gear models made of epoxy castings (Araldite B) were loaded in a specially built gear-loading fixture and were stress frozen. Gear cutters of Wildhaber-Novikov gears developed at the laboratory were used for the preparation of these three-dimensional gear models. The stress-frozen models were analyzed using the conventional slicing technique to study the contact and bending-stress distribution along the face width. The load-carrying capacity in terms of contact stress and bending stress has been studied for different face widths and helix angles. Twenty-deg pressure angle, 14-mm module gears of alladdendum type of Wildhaber-Novikov gears with different helix angles up to 40 deg were tested. The helical-overlap ratio used was 1.0. The conventional profile parameters were employed for the manufacture of gear cutters of end-mill type. The decrease in contact and bending strength with increase in the helix angle or decrease in the face width, as obtained from this photoelastic method of stress analysis has been compared with existing theoretical results. © 1977 Society for Experimental Mechanics, Inc

Expression profiling of oocyte specific genes, transcription factors and microRNAs during early embryonic development in rainbow trout (Onchorhyncus mykiss)

Genes specifically expressed in oocytes are important for the development of oocytes and early embryos. By analyzing ESTs from a rainbow trout oocyte cDNA library, we identified a novel EST sequence that does not show homology to any sequences in the GenBank. Analysis of tissue distribution by RT-PCR revealed that this gene was only expressed in unfertilized oocytes. Sequencing of the EST clone identified a cDNA of 3163 bp. Northern blot analysis showed the novel gene has a single transcript of 3.4 kb. Additional 5\u27 sequence was obtained by 5\u27 RACE, extending the novel cDNA to 3333 bp. Analysis of the full length cDNA identified an open reading frame encoding a protein of 564 amino acids. The novel protein contains a conserved oxysterol binding protein (OSBP) domain at the C terminus that is characteristic of OSBP-related proteins implicated in lipid metabolism. Therefore, we named the novel gene as Oocyte-specific Oxysterol binding protein Related-Protein of Trout (OORP-T). In situ hybridization showed that the OORP-T mRNA appears to be confined to the cytoplasm of vitellogenic oocytes. Transcription of OORP-T appears to start during pre-vitellogenesis and increases steadily, reaching its peak in the late vitellogenic stage. OORP-T transcript is abundantly present in unfertilized eggs but the level drops significantly in day 2 embryos and continues to decline in day 7 embryos after which it remains low. It is proposed that OORP-T may play an important role in the utilization of yolk derived lipid products during oocyte development and early stages of embryonic development in rainbow trout.;Maternal-zygotic transition (MZT) is the first major transition in early development leading to the activation of embryonic genome. Effective transcription machinery including transcription factors must be in place during MZT for it to occur. Therefore, measuring the transcript abundance of key transcription factors prior to and after MZT can give important clues about the roles of transcription factors during this process. In this study, we quantitatively measured mRNA abundance of 9 selected transcription factors (Figla, P300, YY1, HMGA1, HMGB1, HMGN1, ATF-1, TEAD2 and OCT-4) in unfertilized eggs and early stage embryos from day 1 through day 7 post fertilization using quantitative real time PCR. Our results demonstrate that significant amounts of mRNA for all transcription factors studied are present in unfertilized eggs and day 1 embryos, and the expression of all transcription factors reaches minimum levels in day 2 embryos. While some transcription factors remain at low levels of expression throughout late stage development, others show significant increase of expression following embryonic genome activation. The expression patterns of these transcription factors are suggestive of their roles in MZT as well as in early development in rainbow trout.;Current literature and our results on expression patterns of oocyte specific genes and transcription factors suggest global but highly regulated maternal mRNA degradation at the time of embryonic genome activation (EGA). We hypothesized that microRNAs (miRNAs), naturally occurring 19-21bp long post-transcriptional regulators, are involved in this degradation process. We analyzed the expression pattern of dicer, an enzyme required for the processing of microRNAs. Dicer is abundantly expressed until 24 hours post-fertilization and gets down-regulated afterwards. This supports the hypothesis that dicer processes mature miRNAs during these stages and these miRNAs in turn degrade maternal mRNAs. To identify candidate microRNAs involved in this process, we constructed a miRNA library from a pool of oocytes and early stage embryos (0 hour post-fertilization through 96 hours post-fertilization). Sequencing analysis of clones showed that there are at least 15 miRNAs expressed during these stages, 4 of which are novel to rainbow trout. We carried out quantitative real-time PCR to learn more about their expression pattern. Our results show that several microRNAs are up-regulated when maternal RNAs are degraded. Stat3, a transcription factor which is involved in activating the transcription of miR-21 is also abundantly expressed in early rainbow trout embryos. Taken together, these results indicate that up-regulated microRNAs, some induced by stat3, could be responsible for degradation of maternal mRNAs in early embryos.;Identification and characterization of a novel oocyte specific gene with a conserved domain that is involved in oxysterol (a metabolite of cholesterol, a precursor molecule of all steroid hormones) metabolism is described here. Expression pattern of OORP-T follows the pattern of estrogen during oogenesis indicating its unique role in oogenesis and early embryonic development although the functions of OORP-T remain to be discovered. None the less, the OORP-T can potentially be used as a marker in selecting for high growth, better nutritional efficiency, disease resistance etc. Based on the results of studies on expression pattern of transcription factor mRNAs and microRNAs, it appears that microRNAs may be involved in maternal mRNAs degradation before EGA. The microRNAs identified and characterized here might also serve as markers for above mentioned economically important traits especially because microRNA might be regulating several target genes involved in any of the above mentioned phenotypes

Shock tube study of the fuel structure effects on the chemical kinetic mechanisms responsible for soot formation, part 2

Soot formation in oxidation of allene, 1,3-butadiene, vinylacetylene and chlorobenzene and in pyrolysis of ethylene, vinylacetylene, 1-butene, chlorobenzene, acetylen-hydrogen, benzene-acetylene, benzene-butadiene and chlorobenzene-acetylene argon-diluted mixtures was studied behind reflected shock waves. The results are rationalized within the framework of the conceptual models. It is shown that vinylacetylene is much less sooty than allene, which indicates that conjugation by itself is not a sufficient factor for determining the sooting tendency of a molecule. Structural reactivity in the context of the chemical kinetics is the dominant factor in soot formation. Detailed chemical kinetic modeling of soot formation in pyrolysis of acetylene is reported. The main mass growth was found to proceed through a single dominant route composed of conventional radical reactions. The practically irreversible formation reactions of the fused polycyclic aromatics and the overshoot by hydrogen atom over its equilibrium concentration are the g-driving kinetic forces for soot formation

Finite Element Development for Analytical of Smart Structure

In the present study, a numerical solution bas ed on the finite element method has been dev eloped to analyze the deformation, electr ic potentials of a piezoelectric smart structure s ubjected to external mechanical or electrical lo adings.The formulation of the finite element for st atic analysis has been presented based on isoparametric formulation. The element considered in the present study is eight noded hexahedral elements. A computer code based on the above formulation has been developed using MA TLAB software to solve the three dimensional structures integrated with piezoelements. The experiments have been conducted on the piezoelectric smart structures consisting carbon epoxy beam and the results obtain ed were used for validating the present finite element code developed and found to have good agreemen

Evaluation of antidepressant activity of tramadol in albino mice using forced swim model

Background: The fact that tramadol can be used as an antidepressant, has been already proved by some animal studies. The objective of the present study was to evaluate antidepressant activity of tramadol in albino mice using forced swim model.Methods: Forced swimming test (FST) model was used to evaluate the antidepressant effect. Mice in the group "I" were given normal saline. Mice in the group II were given imipramine. Mice in the group III were given tramadol 10mg/kg. Mice in the group IV were given tramadol 20mg/kg. Mice in the group V were given tramadol 40mg/kg. All doses in all groups were given by intra peritoneum route.Results: The average values of immobility in group I were higher significantly compared to group III, IV and V. The values of group I and group II were found to be comparable. It was found that the baseline mean value was 196.33 which reduced to 5.16 with the effect of imipramine where imipramine was given to those mice. But in tramadol 10mg group, it was highest, and it came down to 40.66 and as the dose of tramadol was increased, the immobility time reduced from 40.66 at 10mg dose to 31.33 at 20mg dose and finally to 13.33mg at 40mg dose.Conclusions: Considering the results of two different animal models of depression it can be concluded that Tramadol has antidepressant activity at 10mg, 20mg, 40mg which was almost similar to Imipramine