4-(Imidazol-1-yl)benzoic acid

In the title mol­ecule, C10H8N2O2, the imidazole and benzene rings form a dihedral angle of 14.5 (1)°. In the crystal, inter­molecular O—H⋯N hydrogen bonds link the mol­ecules into chains extending in [01], which are further linked into sheets parallel to (102) through weak C—H⋯O inter­actions

Optimized Design on the Width and Spacing of the Cross Passageway in Tunnels

AbstractCross passageways have been commonly applied in the evacuation system of tunnels, and the width and spacing of the cross passageways decide the evacuation capacity of the tunnel. In design, increasing the width of the cross passageways and reducing their spacing can improve the evacuation ability of tunnels. However, it will certainly increase the cost of the project. Under the precondition of meeting evacuation requirements, an optimization model was established in this article, which aimed at reducing the cost of the project. Finally, discussions on the application of this optimization model were carried on, and this method may provide reference for designing cross passageways

Impact of Lycium barbarum polysaccharide on apoptosis in Mycoplasma-infected splenic lymphocytes

Purpose: To evaluate the effect of Lycium barbarum polysaccharide (LBP) on apoptosis in Mycoplasma-infected splenic lymphocytes (SLs), and the underlying mechanisms.Methods: SLs isolated from C57BL/6J mice were infected with Mycoplasma. The infected SLs were administered at different concentrations of LBP for 4 h, and the proportions of apoptotic cells and levels of relative reactive oxygen species (ROS) were determined by flow cytometry. The expressions of proapoptotic genes and endogenous antioxidant enzymes were investigated by real-time polymerase chain reaction (RT-PCR) and Western blotting.Results: LBP treatment produced dose-dependent reductions in apoptotic ratio and intracellular ROS levels of SLs (p < 0.05). In addition, the expressions of pro-apoptotic genes were decreased by LBP treatment with respect to mRNA and protein levels (p < 0.05). In contrast, mRNA and protein levels of anti-apoptotic factor Bcl-2 were significantly increased in a dose-dependent manner (p < 0.05). Furthermore, RT-PCR and Western blot results demonstrated that the expression levels of mRNA and proteins in Nrf2, HO-1 and NQO1 were up-regulated by Mycoplasma infection (p < 0.01), and further increased by LBP treatment (p < 0.05).Conclusion: LBP exerts a hyperactive antioxidant response encoded by Nrf2 to protect SLs from apoptosis induced by ROS-related oxidative damage after Mycoplasma infection. These results suggest that LBP may serve as a beneficial and dietary anti-Mycoplasma and anti-apoptotic agent.Keywords: Lycium barbarum polysaccharide, Splenic lymphocytes, ROS, Caspase-3, Bax, Nrf

A New Concept to Reveal Protein Dynamics Based on Energy Dissipation

Protein dynamics is essential for its function, especially for intramolecular signal transduction. In this work we propose a new concept, energy dissipation model, to systematically reveal protein dynamics upon effector binding and energy perturbation. The concept is applied to better understand the intramolecular signal transduction during allostery of enzymes. The E. coli allosteric enzyme, aspartokinase III, is used as a model system and special molecular dynamics simulations are designed and carried out. Computational results indicate that the number of residues affected by external energy perturbation (i.e. caused by a ligand binding) during the energy dissipation process shows a sigmoid pattern. Using the two-state Boltzmann equation, we define two parameters, the half response time and the dissipation rate constant, which can be used to well characterize the energy dissipation process. For the allostery of aspartokinase III, the residue response time indicates that besides the ACT2 signal transduction pathway, there is another pathway between the regulatory site and the catalytic site, which is suggested to be the β15-αK loop of ACT1. We further introduce the term “protein dynamical modules” based on the residue response time. Different from the protein structural modules which merely provide information about the structural stability of proteins, protein dynamical modules could reveal protein characteristics from the perspective of dynamics. Finally, the energy dissipation model is applied to investigate E. coli aspartokinase III mutations to better understand the desensitization of product feedback inhibition via allostery. In conclusion, the new concept proposed in this paper gives a novel holistic view of protein dynamics, a key question in biology with high impacts for both biotechnology and biomedicine

A possible Macronova in the late afterglow of the `long-short' burst GRB 060614

Long-duration ($>2$ s) $\gamma$-ray bursts that are believed to originate from the death of massive stars are expected to be accompanied by supernovae. GRB 060614, that lasted 102 s, lacks a supernova-like emission down to very stringent limits and its physical origin is still debated. Here we report the discovery of near-infrared bump that is significantly above the regular decaying afterglow. This red bump is inconsistent with even the weakest known supernova. However, it can arise from a Li-Paczy\'{n}ski macronova $-$ the radioactive decay of debris following a compact binary merger. If this interpretation is correct GRB 060614 arose from a compact binary merger rather than from the death of a massive star and it was a site of a significant production of heavy r-process elements. The significant ejected mass favors a black hole-neutron star merger but a double neutron star merger cannot be ruled out.Comment: Minor revision; The version published in Nature Communication

Performance improvement of three-body radiative diode driven by graphene surface plasmon polaritons

As an analogue to electrical diode, a radiative thermal diode allows radiation to transfer more efficiently in one direction than in the opposite direction by operating in a contactless mode. In this study, we demonstrated that, within the framework of three-body photon thermal tunneling, the rectification performance of three-body radiative diode can be greatly improved by bringing graphene into the system. The system is composed of three parallel slabs, with the hot and cold terminals of the diode coated with graphene films, and the intermediate body made of vanadium dioxide (VO2). The rectification factor of the proposed radiative thermal diode reaches 300 % with a 350 nm separation distance between the hot and cold terminals of the diode. With the help of graphene, the rectification performance of the radiative thermal diode can be improved by over 11 times. By analyzing the spectral heat flux and energy transmission coefficients, it was found that the improved performance is primarily attributed to the surface plasmon polaritons (SPPs) of graphene. They excite the modes of insulating VO2 in the forward-biased scenario by forming strongly coupled modes between graphene and VO2, and thus dramatically enhance the heat flux. While, for the reverse-biased scenario, the VO2 is at its metallic state and thus graphene SPPs cannot work by three-body photon thermal tunneling. Furthermore, the improvement was also investigated for different chemical potentials of graphene, and geometric parameters of the three-body system. Our findings demonstrate the feasibility of using thermal-photon-based logical circuits, creating radiation-based communication technology, and implementing thermal management approaches at the nanoscale