Researches on Heat Pump System using Rotary Compressor in Electric Vehicle

In China, electric vehicles (EVs) are becoming increasing popular. With several years practical operation experiences, a lot of news reports reveal the existing electrical supplementary heating can dramatically impact the driving range of EVs under cold weather in north China. The high efficient electric heat pump system has become the research hotspot, but previous research show the heat pump operation could supply adequate heating capacity only in mild weather conditions when the working fluid is R134a. Since the user can’t change environment temperature, choose a high pressure working fluid to have better heating performance become a realistic choice. Now the aluminum scroll compressor is wildly used in EVs, but because of the material and structure, it can’t endure the long term high pressure operation. This paper adopted the low cost steel rotary compressor and high pressure working fluid to build the EV heat pump system. The heat pump cycles using R134a, R407c and R290 have been theoretically analyzed; the rotary compressor has been redesigned to respectively apply the R134a, R407c and R290; the heat pump test rig has been build; three combinations (compressor, oil and working fluid) under the same cold weather conditions have been experimentally researched. Results showed the rotary compressor with the high pressure working fluid applied system can generate adequate heating capacity with less energy

Probiotic Therapy for Treating Behavioral and Gastrointestinal Symptoms in Autism Spectrum Disorder: A Systematic Review of Clinical Trials

The therapeutic potentials of probiotics in autism spectrum disorder (ASD) remains controversial, with the only existing systematic review on this topic published in 2015. Results from new trials have become available in recent years. We therefore conducted an updated systematic review, to assess the efficacy of probiotics in relieving behavioral symptoms of ASD and gastrointestinal comorbidities. Our review includes two randomized controlled trials, which showed improvement of ASD behaviors, and three open trials, all which exhibited a trend of improvement. Four of these trials concluded from subjective measures that gastrointestinal function indices showed a trend of improvement with probiotic therapy. Additional rigorous trials are needed to evaluate the effects of probiotic supplements in ASD

A thermodynamically consistent quasi-particle model without temperature-dependent infinity of the vacuum zero point energy

In this paper, an improved quasi-particle model is presented. Unlike the previous approach of establishing quasi-particle model, we introduce a classical background field (it is allowed to depend on the temperature) to deal with the infinity of thermal vacuum energy which exists in previous quasi-particle models. After taking into account the effect of this classical background field, the partition function of quasi-particle system can be made well-defined. Based on this and following the standard ensemble theory, we construct a thermodynamically consistent quasi-particle model without the need of any reformulation of statistical mechanics or thermodynamical consistency relation. As an application of our model, we employ it to the case of (2+1) flavor QGP at zero chemical potential and finite temperature and obtain a good fit to the recent lattice simulation results of S. Borsanyi $et$ $al$. A comparison of the result of our model with early calculations using other models is also presented. It is shown that our method is general and can be generalized to the case where the effective mass depends not only on the temperature but also on the chemical potential.Comment: 7 pages, 4 figure

Extracellular interactions and ligand degradation shape the nodal morphogen gradient

t The correct distribution and activity of secreted signaling proteins called morphogens is required for many developmental processes. Nodal morphogens play critical roles in embryonic axis formation in many organisms. Models proposed to generate the Nodal gradient include diffusivity, ligand processing, and a temporal activation window. But how the Nodal morphogen gradient forms in vivo remains unclear. Here, we have measured in vivo for the first time, the binding affinity of Nodal ligands to their major cell surface receptor, Acvr2b, and to the Nodal inhibitor, Lefty, by fluorescence cross-correlation spectroscopy. We examined the diffusion coefficient of Nodal ligands and Lefty inhibitors in live zebrafish embryos by fluorescence correlation spectroscopy. We also investigated the contribution of ligand degradation to the Nodal gradient. We show that ligand clearance via degradation shapes the Nodal gradient and correlates with its signaling range. By computational simulations of gradient formation, we demonstrate that diffusivity, extra-cellular interactions, and selective ligand destruction collectively shape the Nodal morphogen gradient

Observation of first-order quantum phase transitions and ferromagnetism in twisted double bilayer graphene

Twisted graphene multilayers are highly tunable flatband systems for developing new phases of matter. Thus far, while orbital ferromagnetism has been observed in valley polarized phases, the long-range orders of other correlated phases as well as the quantum phase transitions between different orders mostly remain unknown. Here, we report an observation of Coulomb interaction driven first-order quantum phase transitions and ferromagnetism in twisted double bilayer graphene (TDBG). At zero magnetic field, the transitions are revealed in a series of step-like abrupt resistance jumps with prominent hysteresis loop when either the displacement field (D) or the carrier density (n) is tuned across symmetry-breaking boundary near half filling, indicating a formation of ordered domains. It is worth noting that the good turnability and switching of these states gives a rise to a memory performance with a large on/off ratio. Moreover, when both spin and valley play the roles at finite magnetic field, we observe abundant first-order quantum phase transitions among normal metallic states from charge neutral point, orbital ferromagnetic states from quarter filling, and spin-polarized states from half filling. We interpret these first-order phase transitions in the picture of phase separations and spin domain percolations driven by multi-field tunable Coulomb interactions, in agreement with Lifshitz transition from Hartree-Fock calculations. The observed multi-filed tunable domain structure and its hysteresis resembles the characteristics of multiferroics, revealing intriguing magnetoelectric properties. Our result enriches the correlated phase diagram in TDBG for discovering novel exotic phases and quantum phase transitions, and it would benefit other twisted moir\'e systems as well