Global Existence and Stability to the Isothermal Gas Dynamics System with an Outer Force

En este artículo aplicamos el método clásico de viscosidad, junto con la aproximación de flujo y la teoría de la compacidad compensada, para obtener la existencia global de las soluciones entrópicas acotadas para el sistema dinámico de gas isotérmico con una fuente externa. Las estimaciones a priori de L∞ independientes del tiempo se prueban aplicando el principio máximo para un sistema parabólico acoplado no lineal adecuado de dos ecuaciones.In this paper, we apply the classical viscosity method, coupled with the flux approximation and the compensated compactness theory to obtain the global existence of the bounded entropy solutions for the isothermal gas dynamics system with an outer source. The a-priori time-independent L∞ estimates are proved by applying the maximum principle to a suitable nonlinear coupled parabolic system of two equations

Development of small interfering RNA delivery system using PEI-PEG-APRPG polymer for antiangiogenic vascular endothelial growth factor tumor-targeted therapy

Zong-Xia Lu1, Li-Ting Liu1,2, Xian-Rong Qi11Department of Pharmaceutics, School of Pharmaceutical Sciences, Peking University, Beijing, People's Republic of China; 2Department of Pharmacy, School and Hospital of Stomatology, Peking University, Beijing, People's Republic of ChinaBackground: Small interfering RNA (siRNA) can silence target genes in the cytoplasm and be a major tool in gene therapy. Vascular endothelial growth factor (VEGF), a potent regulator of angiogenesis, is overexpressed in most tumors and is closely associated with tumor growth and metastasis. It has been shown that inhibition of VEGF expression by siRNA is an effective and useful method for antiangiogenic tumor therapy.Methods: In the present study, we synthesized a targeted delivery system of PEI-PEG-APRPG incorporating angiogenic vessel-homing Ala-Pro-Arg-Pro-Gly (APRPG) peptide into cationic polyethylenimine (PEI) via a hydrophilic poly(ethylene glycol) (PEG) spacer.Results: PEI-PEG-APRPG effectively condensed siRNA into 20–50 nm nanoparticles with a positive surface charge using a suitable N/P ratio. The siRNA/PEI-PEG-APRPG complex effectively enhanced the stability of siRNA in RNase A, and improved the proliferation-inhibiting ability and transfection efficiency of siRNA in vitro and tumor accumulation in vivo. In addition, the siRNA/PEI-PEG-APRPG complex exhibited high efficiency as antitumor therapy with regard to tumor growth, microvessel density, and VEGF protein and mRNA levels.Conclusion: These findings suggest that PEI-PEG-APRPG effectively delivers siRNA to tumors overexpressing VEGF and thereby inhibits tumor growth.Keywords: PEI-PEG-APRPG, VEGF siRNA, gene delivery, tumor-targeted, antiangiogenic therap

Evidence for a population of beamed radio intermediate quasars

Whether radio intermediate quasars possess relativistic jets as radio-loud quasars is an important issue in the understanding of the origin of radio emission in quasars. In this letter, using the two-epoch radio data obtained during Faint Image of Radio Sky at Twenty centimeter sky (FIRST) and NOAO VLA Sky Survey (NVSS), we identify 89 radio variable sources in the Sloan Digital Sky Survey. Among them, more than half are radio intermediate quasars (RL=f2cm/f2500A<250). For all objects with available multiple band radio observations, the radio spectra are either flat or inverted. The brightness temperature inferred from the variability is larger than the synchrotron-self Compton limit for a stationary source in 87 objects, indicating of relativistic beaming. Considering the sample selection and viewing angle effect, we conclude that relativistic jets probably exist in a substantianl fraction of radio intermediate quasars.Comment: 15 pages, 4 figures, 1 table, Accepted to the Astrophysical Journa

(Methanol-κO)bis­{2-meth­oxy-6-[(4-methyl­phen­yl)iminiometh­yl]phenolato-κ2 O,O′}tris­(nitrato-κ2 O,O′)lanthanum(III)

The asymmetric unit of title compound, [La(NO3)3(C15H15NO2)2(CH3OH)], consists of two Schiff base 2-meth­oxy-6-[(4-methyl­phen­yl)iminiometh­yl]phenolato (HL) ligands, three independent nitrate anions and one methanol mol­ecule coordinated to LaIII. The coordination environment of the LaIII ion is formed by eleven O atoms. Three bidentate nitrate anions coordinate to the LaIII ion, while two HL ligands chelate the metal center with O atoms from the phenolate and meth­oxy groups. The HL ligands are zwitterionic, with protonated imine N atoms. The coordination sphere is completed by one methanol mol­ecule. The protonated imine N atoms are involved in intra­molecular N—H⋯O hydrogen bonds with the phen­oxy groups and nitrate ligands. One O atom of one nitrate group is disordered over two sites of equal occupancy

Revising inelastic dark matter direct detection by including the cosmic ray acceleration

The null signal from collider and dark matter (DM) direct detector experiments makes the interaction between DM and visible matter too small to reproduce the correct relic density for many thermal DM models. The remaining parameter space indicates that two almost degenerated states in the dark sector, the inelastic DM scenario, can co-annihilate in the early universe to produce the correct relic density. Regarding the direct detection of the inelastic DM scenario, the virialized DM component from the nearby halo is nonrelativistic and not able to excite the DM ground state, even if the relevant couplings can be considerable. Thus, a DM with a large mass splitting can evade traditional virialized DM direct detection. In this study, we connect the concept of cosmic-ray accelerated DM in our Milky Way and the direct detection of inelastic scattering in underground detectors to explore spectra that result from several interaction types of the inelastic DM. We find that the mass splitting $\delta<\mathcal{O}(1~{\rm MeV})$ can still be reachable for cosmic ray accelerated DM with mass range $1~{\rm MeV}<m_{\chi_1}<100~{\rm GeV}$ and sub-GeV light mediator using the latest PandaX-4T data, even though we conservatively use the astrophysical parameter (effective length) $D_{\rm eff}=1$ kpc.Comment: 38 pages, 12 figures, JHEP accepted versio

Limiting Magnitudes of the Wide Field Survey Telescope (WFST)

Expected to be of the highest survey power telescope in the northern hemisphere, the Wide Field Survey Telescope (WFST) will begin its routine observations of the northern sky since 2023. WFST will produce a lot of scientific data to support the researches of time-domain astronomy, asteroids and the solar system, galaxy formation and cosmology and so on. We estimated that the 5 $\sigma$ limiting magnitudes of WFST with 30 second exposure are $u=22.31$ mag, $g=23.42$ mag, $r=22.95$ mag, $i=22.43$ mag, $z=21.50$ mag, $w=23.61$ mag. The above values are calculated for the conditions of $airmass=1.2$, seeing = 0.75 arcsec, precipitable water vapour (PWV) = 2.5 mm and Moon-object separation = $45^{\circ}$ at the darkest New Moon night of the Lenghu site (V=22.30 mag, Moon phase $\theta=0^{\circ}$). The limiting magnitudes in different Moon phase conditions are also calculated. The calculations are based on the empirical transmittance data of WFST optics, the vendor provided CCD quantum efficiency, the atmospherical model transmittance and spectrum of the site. In the absence of measurement data such as sky transmittance and spectrum, we use model data.Comment: 12 pages, 5 figures, accepted by RAA (Research in Astronomy and Astrophysics

Chemical structure, properties and potential applications of surfactin, as well as advanced strategies for improving its microbial production

Surfactin, a cyclic lipopeptide produced by microbes belonging to the genus Bacillus, is one of the most effective biosurfactants available in many industrial fields. However, its low production and high cost have intensively constrained its commercial applications. In this review, we first summarize the molecular structure, biological properties, beneficial roles and potential applications of surfactin in the fields of medical care and food safety, highlighting the great medical and commercial values of making its industrial production into reality. Further, genetic regulation for surfactin biosynthesis and advanced strategies for enhancing its microbial production, including optimizing fermentation conditions, rational genetic engineering and synthetic biology combined with metabolic engineering approaches, are elucidated. Finally, prospects for improving surfactin biosynthesis are discussed, and the establishment of suitable chassis hosts for exogenous production of surfactin might serve as an important strategy in future research

Neuroprotective Effect of Ginkgolide B on Bupivacaine-Induced Apoptosis in SH-SY5Y Cells

Local anesthetics are used routinely and effectively. However, many are also known to activate neurotoxic pathways. We tested the neuroprotective efficacy of ginkgolide B (GB), an active component of Ginkgo biloba, against ROS-mediated neurotoxicity caused by the local anesthetic bupivacaine. SH-SY5Y cells were treated with different concentrations of bupivacaine alone or following preincubation with GB. Pretreatment with GB increased SH-SY5Y cell viability and attenuated intracellular ROS accumulation, apoptosis, mitochondrial dysfunction, and ER stress. GB suppressed bupivacaine-induced mitochondrial depolarization and mitochondria complex I and III inhibition and increased cleaved caspase-3 and Htra2 expression, which was strongly indicative of activation of mitochondria-dependent apoptosis with concomitantly enhanced expressions of Grp78, caspase-12 mRNA, protein, and ER stress. GB also improved ultrastructural changes indicative of mitochondrial and ER damage induced by bupivacaine. These results implicate bupivacaine-induced ROS-dependent mitochondria, ER dysfunction, and apoptosis, which can be attenuated by GB through its antioxidant property

VASP Activation via the Gα13/RhoA/PKA Pathway Mediates Cucurbitacin-B-Induced Actin Aggregation and Cofilin-Actin Rod Formation

Cucurbitacin B (CuB), a potent antineoplastic agent of cucurbitacin triterpenoids, induces rapid disruption of actin cytoskeleton and aberrant cell cycle inhibiting carcinogenesis. However, the underlying molecular mechanism of such anticancer effects remains incompletely understood. In this study, we showed that CuB treatment rapidly induced vasodilator-stimulated phosphoprotein (VASP) phosphorylation (i.e. activation) at the Ser157 residue and generated VASP clumps which were co-localized with amorphous actin aggregates prior to the formation of highly-ordered cofilin-actin rods in melanoma cells. Knockdown of VASP or inhibition of VASP activation using PKA-specific inhibitor H89 suppressed CuB-induced VASP activation, actin aggregation and cofilin-actin rod formation. The VASP activation was mediated by cAMP-independent PKA activation as CuB decreased the levels of cAMP while MDL12330A, an inhibitor of adenylyl cyclase, had weak effect on VASP activation. Knockdown of either Gα13 or RhoA not only suppressed VASP activation, but also ameliorated CuB-induced actin aggregation and abrogated cofilin-actin rod formation. Collectively, our studies highlighted that the CuB-induced actin aggregation and cofilin-actin rod formation was mediated via the Gα13/RhoA/PKA/VASP pathway