RSM and v2 -f predictions of an impinging jet in a cross flow on a heated surface and on a pedestal

The objective of this study is to compare the performance of the v 2 -f and the Reynolds Stress Model (RSM) turbulence model with a two-layer wall treatment for the prediction of the mean velocity field, the turbulence characteristics and the heat transfer rate of the normal impinging jet and also impinging jet in a cross-flow configuration. The numerical predictions are validated against detailed experimental measurements, using PIV and a low-wavelength infrared imaging system, for the measurement of turbulent flow features and surface temperatures. A linear pressure-strain model is used in the RSM. The turbulent heat fluxes are modeled by the eddy-diffusivity hypothesis with a constant value of the turbulent Prandtl number. The mesh is refined enough near the solid walls (y+≈1) to adequately resolve the boundary layers. The results show several complex flow-related phenomena that affect the cooling performance, such as stagnation point, separation region, curvature effects and re-circulating wake flows. These phenomena have to be accurately captured before a good prediction of the heat transfer rate can be attained. A comparison between the v 2 -f and RSM results in the stagnation region, in the other near-wall regions and in the free shear region will be presented in order to evaluate the performance of the two models

Effect of hydroalcoholic extract of Matricaria chamomilla on passive avoidance memory and pain induced by global cerebral ischemia in Wistar rat

زمینه و هدف : ایسکمی مغزی و خونرسانی مجدد علت اصلی ناتوانی جدی و طولانی مدت در جهان است. هدف از مطالعه حاضر بررسی اثر عصاره هیدروالکلی بابونه بر اختلالات حافظه و درد ناشی از ایسکمی بود. روش بررسی: گل‌های خشک بابونه (Matricaria chamomilla) از عطاری تهیه شده و توسط الکل 70 درصد عصاره گیری شد. حیوانات به صورت تصادفی به 6 گروه 7 تایی تقسیم شدند. گروه کنترل فقط نرمال سالین دریافت کردند، گروه ایسکمی تحت ایسکمی قرار گرفته و نرمال سالین دریافت کردند، گروه شاهد(sham): تحت جراحی قرار گرفتند بدون اینکه شریان‌های کاروتید آن‌ها بسته شود. گروه‌های درمانی با عصاره تحت ایسکمی قرار گرفته و عصاره بابونه را به صورت داخل صفاقی در دوز 50، 100 و 200 میلی‌گرم بر کیلوگرم وزن بدن دریافت کردند. تست رفتاری توسط شاتل باکس و تست ضد درد توسط تست تیل فیلیک انجام شد. یافته ها : عصاره بابونه در غلظت‌های 50، 100 و 200 میلی‌گرم بر کیلوگرم حافظه احترازی غیرفعال موش‌های صحرایی تحت ایسکمی را به طور معنی‌دار افزایش داد. علاوه بر این عصاره بابونه زمان تأخیر ظهور رفلکس دردناک دم را در تست تیل فلیک به طور معنی‌داری افزایش داد و غلظت 50 میلی‌گرم بر کیلوگرم عصاره اثر بیشتری نسبت به غلظت‌های بالاتر آن نشان داد. بحث و نتیجه گیری: نتایج مطالعه حاضر حاکی از اثرات حفاظتی عصاره بابونه در برابر اختلال حافظه احترازی و درد ایجاد شده در اثر ایسکمی بود که احتمالا به دلیل اثرات آنتی‌اکسیدانی و ضدالتهابی عصاره گیاه می‌باش

First-order phase transition from hypernuclear matter to deconfined quark matter obeying new constraints from compact star observations

We reconsider the problem of the hyperon puzzle and its suggested solution by quark deconfinement within the two-phase approach to hybrid compact stars with recently obtained hadronic and quark matter equations of state. For the hadronic phase we employ the hypernuclear equation of state from the lowest order constrained variational method and the quark matter phase is described by a sufficiently stiff equation of state based on a color superconducting nonlocal Nambu-Jona-Lasinio model with constant (model nlNJLA) and with density-dependent (model nlNJLB) parameters. We study the model dependence of the phase transition obtained by a Maxwell construction. Our study confirms that also with the present set of equations of state quark deconfinement presents a viable solution of the hyperon puzzle even for the new constraint on the lower limit of the maximum mass from PSR J0740+6620. In this work we provide with model nlNJLB for the first time a hybrid star EoS with an intermediate hypernuclear matter phase between the nuclear and color superconducting quark matter phases, for which the maximum mass of the compact star reaches $2.2~M_\odot$, in accordance with most recent constraints. In model nlNJLA such a phase cannot be realised because the phase transition onset is at low densities, before the hyperon threshold density is passed. We discuss possible consequences of the hybrid equation of state for the deconfinement phase transition in symmetric matter as it will be probed in future heavy-ion collisions at FAIR, NICA and corresponding energy scan programs at the CERN and RHIC facilities.Comment: 37 pages, 13 figures, 1 table, references added, text and figures revised, version accepted for publication in Phys. Rev.

Controlling surface statistical properties using bias voltage: Atomic force microscopy and stochastic analysis

The effect of bias voltages on the statistical properties of rough surfaces has been studied using atomic force microscopy technique and its stochastic analysis. We have characterized the complexity of the height fluctuation of a rough surface by the stochastic parameters such as roughness exponent, level crossing, and drift and diffusion coefficients as a function of the applied bias voltage. It is shown that these statistical as well as microstructural parameters can also explain the macroscopic property of a surface. Furthermore, the tip convolution effect on the stochastic parameters has been examined.Comment: 8 pages, 11 figures

Differentiation of mouse embryonic stem cells into cells with spermatogonia-like morphology with chemical intervention-dependent increased gene expression of LIM homeobox 1 (Lhx1).

Spermatogonial stem cells (SSCs) originate from gonocytes that differentiate from primordial germ cells (PGCs). In the developing mouse testis, expression of the gene LIM homeobox 1 (Lhx1) marks the most undifferentiated SSCs, which has not yet been reported for spermatogonia-like cells generated in vitro. Previously, it was shown that a chemical intervention in male mouse embryonic stem (ES) cells in serum culture, including Sirtuin 1 (SIRT1) inhibitor Ex-527, DNA methyltransferase (DNMT) inhibitor RG-108 and electrophilic redox cycling compound tert-butylhydroquinone (tBHQ), was associated with molecular markers of PGC to gonocyte differentiation. Here, we report the in vitro differentiation of male mouse ES cells, cultured under dual chemical inhibition of GSK3β and MEK (2i) with leukemia inhibitory factor (LIF) (2iL) and serum, into cells with spermatogonia-like morphology (CSMs) and population-averaged expression of spermatogonia-specific genes by removal of 2iL and a specific schedule of twice daily partial medium replacement. Combination of this new protocol with the previously reported chemical intervention increased population-averaged gene expression of Lhx1 in the resulting CSMs. Furthermore, we detected single CSMs with strong nuclear LHX1/5 protein signal only in the chemical intervention group. We propose that further investigation of CSMs may provide new insights into male germline development

Differentiation of mouse embryonic stem cells into cells with spermatogonia-like morphology with chemical intervention-dependent increased gene expression of LIM homeobox 1 (Lhx1)

Spermatogonial stem cells (SSCs) originate from gonocytes that differentiate from primordial germ cells (PGCs). In the developing mouse testis, expression of the gene LIM homeobox 1 (Lhx1) marks the most undifferentiated SSCs, which has not yet been reported for spermatogonia-like cells generated in vitro. Previously, it was shown that a chemical intervention in male mouse embryonic stem (ES) cells in serum culture, including Sirtuin 1 (SIRT1) inhibitor Ex-527, DNA methyltransferase (DNMT) inhibitor RG-108 and electrophilic redox cycling compound tert-butylhydroquinone (tBHQ), was associated with molecular markers of PGC to gonocyte differentiation. Here, we report the in vitro differentiation of male mouse ES cells, cultured under dual chemical inhibition of GSK3β and MEK (2i) with leukemia inhibitory factor (LIF) (2iL) and serum, into cells with spermatogonia-like morphology (CSMs) and population-averaged expression of spermatogonia-specific genes by removal of 2iL and a specific schedule of twice daily partial medium replacement. Combination of this new protocol with the previously reported chemical intervention increased population-averaged gene expression of Lhx1 in the resulting CSMs. Furthermore, we detected single CSMs with strong nuclear LHX1/5 protein signal only in the chemical intervention group. We propose that further investigation of CSMs may provide new insights into male germline development

LOCV calculation for Beta-stable matter at finite temperature

The method of lowest-order constrained variational, which predicts reasonably the nuclear matter semi-empirical data is used to calculate the equation of state of beta-stable matter at finite temperature. The Reid soft-core with and without the N-$\Delta$ interactions which fits the N-N scattering data as well as the $UV_{14}$ potential plus the three-nucleon interaction are considered in the nuclear many-body Hamiltonian. The electron and muon are treated relativistically in the total Hamiltonian at given temperature, to make the fluid electrically neutral and stable against beta decay. The calculation is performed for a wide range of baryon density and temperature which are of interest in the astrophysics. The free energy, entropy, proton abundance, etc. of nuclear beta-stable matter are calculated. It is shown that by increasing the temperature, the maximum proton abundance is pushed to the lower density while the maximum itself increases as we increase the temperature. The proton fraction is not enough to see any gas-liquid phase transition. Finally we get an overall agreement with other many-body techniques, which are available only at zero temperature.Comment: LaTex, 20 page