CFD Simulation of An Oil Flooded Scroll Compressor Using VOF Approach

Liquids have been commonly used in different types of compressors to seal the leakage gaps and to cool the compressed gas in order to increase the efficiency. CFD simulation provides valuable insights to help design engineers to verify, to analyze, and to improve the performance of a compressor. However two phase flow with moving parts and small gaps is a very challenging CFD problem. For compressor simulation, thermal effects and heat transfer are also essential. Therefore simulation of liquid flooded compressors is extremely difficult.  In this paper a full 3D transient CFD model for a generic oil flooded scroll compressor will be described in detail. Volume Of Fluid (VOF) multiphase approach will be used to model gas and liquid phases. Effects of flooded oil will be evaluated by comparing the simulation results for the cases with and without oil. Simulation will also demonstrate that the approaches used in the paper are robust, fast, and user friendly, and can be readily applied to industrial compressor systems

Vacuum induced transparency and photon number resolved Autler-Townes splitting in a three-level system

We study the absorption spectrum of a probe field by a {\Lambda}-type three-level system, which is coupled to a quantized control field through the two upper energy levels. The probe field is applied to the ground and the second excited states. When the quantized control field is in vacuum, we derive a threshold condition to discern vacuum induced transparency (VIT) and vacuum induced Autler- Townes splitting (ATS). We also find that the parameter change from VIT to vacuum induced ATS is very similar to that from broken PT symmetry to PT symmetry. Moreover, we find the photon number resolved spectrum in the parameter regime of vacuum induced ATS when the mean photon number of the quantized control field is changed from zero (vacuum) to a finite number. However, there is no photon number resolved spectrum in the parameter regime of VIT even that the quantized control field contains the finite number of photons. Finally, we further discuss possible experimental realization

Molecular states from D(∗)Dˉ(∗)/B(∗)Bˉ(∗)D^{(*)}\bar{D}^{(*)}/B^{(*)}\bar{B}^{(*)} and D(∗)D(∗)/Bˉ(∗)Bˉ(∗)D^{(*)}D^{(*)}/\bar{B}^{(*)}\bar{B}^{(*)} interactions

In this work, we preform a systematic investigation about hidden heavy and doubly heavy molecular states from the $D^{(*)}\bar{D}^{(*)}/B^{(*)}\bar{B}^{(*)}$ and $D^{(*)}D^{(*)}/\bar{B}^{(*)}\bar{B}^{(*)}$ interactions in the quasipotential Bethe-Salpeter equation (qBSE) approach. With the help of Lagrangians with heavy quark and chiral symmetries, interaction potentials are constructed within the one-boson-exchange model in which we include the $\pi$, $\eta$, $\rho$, $\omega$ and $\sigma$ exchanges, as well as $J/\psi$ or $\Upsilon$ exchange. Possible bound states from the interactions considered are searched for as the pole of scattering amplitude. The results suggest that experimentally observed states, $Z_c(3900)$, $Z_c(4020)$, $Z_b(10610)$, and $Z_b(10650)$, can be related to the $D\bar{D}^{*}$, $D^*\bar{D}^{*}$, $B\bar{B}^{*}$, and $B^*\bar{B}^{*}$ interactions with quantum numbers $I^G(J^P)=1^+(1^{+})$, respectively. The $D\bar{D}^{*}$ interaction is also attractive enough to produce a pole with $0^+(0^+)$ which is related to the $X(3872)$. Within the same theoretical frame, the existence of $D\bar{D}$ and $B\bar{B}$ molecular states with $0(0^+)$ are predicted. The possible $D^*\bar{D}^*$ molecular states with $0(0^+, 1^+, 2^+)$ and $1(0^+)$ and their bottom partners are also suggested by the calculation. In the doubly heavy sector, no bound state is produced from the $DD/\bar{B}\bar{B}$ interaction while a bound state is found with $0(1^+)$ from $DD^*/\bar{B}\bar{B}^*$ interaction. The $D^*D^*/\bar{B}^*\bar{B}^*$ interaction produces three molecular states with $0(1^+)$, $0(2^+)$ and $1(2^+)$.Comment: 7 page

Imperatorin inhibits allergic airway inflammatory reaction and mucin secretion in ovalbumin-induced asthmatic rats

Purpose: To study the therapeutic effects of imperatorin (IPT) on allergic asthma induced by ovalbumin in rats.Methods: Asthma was established in rats by injection of ovalbumin (OVA), and IPT (20, 40 and 80 mg/kg) was administered orally for 21 days. Inflammatory cells and cytokines were determined in the bronchoalveolar lavage fluid (BALF); IgE and histamine in the serum were also determined. Furthermore, MUC-5AC expression in the lung tissue was determined by Western blot assay.Results: Treatment with IPT (20, 40 and 80 mg/kg) decreased inflammatory cells including eosinophils (p < 0.01), neutrophils (p < 0.05), lymphocytes (p < 0.01) and macrophages (p < 0.01). In addition, the four inflammatory cytokines {interleukin (IL) -4, IL-6, IL-13 and tumor necrosis factor (TNF)-α} were significantly decreased by treatment with IPT (20, 40 and 80 mg/kg) dose-dependently (p < 0.01). Furthermore, MUC5AC in lung tissues was significantly down-regulated by treatment with IPT (20, 40 and 80 mg/kg, p < 0.01) in a dose-dependent fashion.Conclusion: The results show that IPT exerts notable therapeutic effects on allergic asthma in rats via suppression of IgE, histamine, inflammatory cells and cytokines, and also by down-regulating MUC5AC.Keywords: Imperatorin, Allergic asthma, Inflammatory cytokines, MUC5AC expression, Eosinophils, Neutrophils, Lymphocyte

Analysis of Down syndrome failed to be diagnosed after prenatal screening: A multicenter study.

To analyze the characters of Down syndrome (DS) who failed to be diagnosed after prenatal screening and hope to be able to improve the programs of prenatal screening and reduce the missed diagnosis of DS. In this multicenter study, we collected the missed cases from 3 prenatal diagnosis centers and analyzed their characters. A total of 126 DS babies failed to be diagnosed after prenatal screening. Their mothers accepted the prenatal screening in second trimester. We collected the mothers' blood and detected the levels of alpha-fetoprotein (AFP) and the free beta subunit of human chorionic gonadotropin (fβhCG) by time-resolved fluoroimmunoassay. The values were also presented as multiples of the median (MoM) and determined the risk of carrying a fetus with DS by Wallace LifeCycle Elipse analysis software. Compared with normal control group, the level of fβhCG and hCG MoM were dramatically increased, while AFP and AFP MoM were decreased. The area under the receiver-operating-characteristic curve of trisomy 21 was 0.8387 for hCG-MoM and AFP-MoM testing. The sensitivity, specificity, positive predictive value, and negative predictive value were 84.6%, 74.8%, 75.4%, and 83.6%, respectively. Meanwhile, the prediction mode was "0.39957 + 1.90897HCG-MOM -3.32713AFP-MOM". It was worthwhile noting that the risk of 65.9% DS missed diagnosis group were higher than 1/1000, 92.9% higher than 1/3000. However, 72.5% cases in normal control group were lower than 1/3000. Only 9.2% mothers would be higher than the value of risk in 1/1000. The prediction mode of hCG MoM and AFP MoM might be able to help us reduce the missed diagnosis. It is also necessary to adjust more reasonable range of noninvasive prenatal testing with further clinical researches