Submillimeter Array Observations of the Molecular Outflow in High-mass Star-forming Region G240.31+0.07

We present Submillimeter Array observations toward the 10^{4.7} Lsun star-forming region G240.31+0.07, in the J=2-1 transition of 12CO and 13CO and at 1.3 mm continuum, as well as the 12CO and 13CO observations from the Caltech Submillimeter Observatory to recover the extended emission filtered out by the interferometer. Maps of the 12CO and 13CO emission show a bipolar, wide-angle, quasi-parabolic molecular outflow, roughly coincident with an IR nebula revealed by the Spitzer 3.6 and 4.5 micron emission. The outflow has ~98 Msun molecular gas, making it one of the most massive molecular outflows known, and resulting in a very high mass-loss rate of 4.1 by 10^{-3} Msun yr^{-1} over a dynamical timescale of 2.4 by 10^4 yr. The 1.3 mm continuum observations with a 4" by 3" beam reveal a flattened dusty envelope of ~150 Msun, which is further resolved with a 1.2" by 1" beam into three dense cores with a total mass of ~40 Msun. The central mm core, showing evidence of active star formation, approximately coincides with the geometric center of the bipolar outflow thus most likely harbors the powering source of the outflow. Overall our observations provide the best case to date of a well-defined wide-angle molecular outflow in a >10^4 Lsun star-forming region. The outflow is morphologically and kinematically similar to low-mass protostellar outflows but has two to three orders of magnitude greater mass, momentum, and energy, and is apparently driven by an underlying wide-angle wind, hence further supports that high-mass stars up to late-O types, even in a crowded clustering environment, can form as a scaled-up version of low-mass star formation.Comment: accepted for publication in the Ap

Stability Analysis of Reinforced Slope Based on Limit Equilibrium Method

Reinforced soil structures are widely used in civil engineering for the slope protection because of their unique advantages. However, the failure mechanism of such structures has not been fully studied. In this paper, the stability analysis of reinforced slopes is carried out based on the limit equilibrium method. Furthermore, the effects of the location, the length and the tensile strength of the reinforcement layers on the safety factor and the critical failure surface are investigated. The research results indicate that the above parameters have great effects on the safety factor and the critical failure surface of the reinforced slope. However, the effects of the length and the tensile strength of the reinforcement on the location where the failure surface starts are not significant. Based on the analysis of computation results, the failure mechanism is analyzed and the optimum design scheme of the reinforced slope is recommended

Local Magnetic Field Role in Star Formation

We highlight distinct and systematic observational features of magnetic field morphologies in polarized submm dust continuum. We illustrate this with specific examples and show statistical trends from a sample of 50 star-forming regions.Comment: 4 pages, 3 figures; to appear in the EAS Proceedings of the 6th Zermatt ISM Symposium "Conditions and Impact of Star Formation from Lab to Space", September 201

Arginine starvation impairs mitochondrial respiratory function in ASS1-deficient breast cancer cells.

Autophagy is the principal catabolic response to nutrient starvation and is necessary to clear dysfunctional or damaged organelles, but excessive autophagy can be cytotoxic or cytostatic and contributes to cell death. Depending on the abundance of enzymes involved in molecule biosynthesis, cells can be dependent on uptake of exogenous nutrients to provide these molecules. Argininosuccinate synthetase 1 (ASS1) is a key enzyme in arginine biosynthesis, and its abundance is reduced in many solid tumors, making them sensitive to external arginine depletion. We demonstrated that prolonged arginine starvation by exposure to ADI-PEG20 (pegylated arginine deiminase) induced autophagy-dependent death of ASS1-deficient breast cancer cells, because these cells are arginine auxotrophs (dependent on uptake of extracellular arginine). Indeed, these breast cancer cells died in culture when exposed to ADI-PEG20 or cultured in the absence of arginine. Arginine starvation induced mitochondrial oxidative stress, which impaired mitochondrial bioenergetics and integrity. Furthermore, arginine starvation killed breast cancer cells in vivo and in vitro only if they were autophagy-competent. Thus, a key mechanism underlying the lethality induced by prolonged arginine starvation was the cytotoxic autophagy that occurred in response to mitochondrial damage. Last, ASS1 was either low in abundance or absent in more than 60% of 149 random breast cancer biosamples, suggesting that patients with such tumors could be candidates for arginine starvation therapy

Infall and outflow motions in the high-mass star forming complex G9.62+0.19

We present the results of a high resolution study with the Submillimeter Array towards the massive star forming complex G9.62+0.19. Three sub-mm cores are detected in this region. The masses are 13, 30 and 165 M_{\sun} for the northern, middle and southern dust cores, respectively. Infall motions are found with HCN (4-3) and CS (7-6) lines at the middle core (G9.62+0.19 E). The infall rate is $4.3\times10^{-3}~M_{\odot}\cdot$yr$^{-1}$. In the southern core, a bipolar-outflow with a total mass about 26 M_{\sun} and a mass-loss rate of $3.6\times10^{-5}~M_{\odot}\cdot$yr$^{-1}$ is revealed in SO ($8_{7}-7_{7}$) line wing emission. CS (7-6) and HCN (4-3) lines trace higher velocity gas than SO ($8_{7}-7_{7}$). G9.62+0.19 F is confirmed to be the driving source of the outflow. We also analyze the abundances of CS, SO and HCN along the redshifted outflow lobes. The mass-velocity diagrams of the outflow lobes can be well fitted by a single power law. The evolutionary sequence of the cm/mm cores in this region are also analyzed. The results support that UC~H{\sc ii} regions have a higher blue excess than their precursors.Comment: 50 pages, 16 figures, 4 table

Aim and shoot: molecule-imprinting polymer coated MoO3 for selective SERS detection and photocatalytic destruction of low-level organic contaminants

A sensitive and selective SERS sensor with easy and excellent recyclability is highly demanded because of its great potential application in complex detection environments. Here, using methylene blue (MB) as a model target, a semiconductor-based SERS substrate composed of a MoO3 nanorod core and a uniform molecule-imprinting polymethacrylic acid shell (MIP) with a thickness of 4 nm was designed and fabricated (MoO3@MIP) to achieve selective detection. The key to the successful coating of the ultrathin uniform MIP shell lies in the pretreatment of a MoO3 core with nitric acid, providing sufficient surficial hydroxyls for the anchoring of a polymer precursor. The molecule-imprinted voids for MB were formed simply via light irradiation as a result of photocatalytic degradation by a MoO3 semiconductor. This core–shell MIP composite shows a high SERS selectivity towards low-level MB in a mixed MB/CV solution. The enhanced factor (EF) is high, at 1.6 × 104. More importantly, the selective detection allows the further photocatalytic recycling of MoO3@MIP in an “aim-and-shoot” way, which well preserves the detection selectivity and sensitivity towards MB at least for 4 cycles. Based on decreased sensitivity with the increasing shell thickness (10–24 nm), a MIP-gating charge transfer mechanism is proposed to demonstrate the high EF instead of the molecule-enrichment effect. This “aim-and-shoot” strategy is expected to push forward the prosperous application of selective SERS for trace detection in versatile environments

Multi-scale physical properties of NGC 6334 as revealed by local relative orientations between magnetic fields, density gradients, velocity gradients, and gravity

We present ALMA dust polarization and molecular line observations toward 4 clumps (I(N), I, IV, and V) in the massive star-forming region NGC 6334. In conjunction with large-scale dust polarization and molecular line data from JCMT, Planck, and NANTEN2, we make a synergistic analysis of relative orientations between magnetic fields ($\theta_{\mathrm{B}}$), column density gradients ($\theta_{\mathrm{NG}}$), local gravity ($\theta_{\mathrm{LG}}$), and velocity gradients ($\theta_{\mathrm{VG}}$) to investigate the multi-scale (from $\sim$30 pc to 0.003 pc) physical properties in NGC 6334. We find that the relative orientation between $\theta_{\mathrm{B}}$ and $\theta_{\mathrm{NG}}$ changes from statistically more perpendicular to parallel as column density ($N_{\mathrm{H_2}}$) increases, which is a signature of trans-to-sub-Alfv\'{e}nic turbulence at complex/cloud scales as revealed by previous numerical studies. Because $\theta_{\mathrm{NG}}$ and $\theta_{\mathrm{LG}}$ are preferentially aligned within the NGC 6334 cloud, we suggest that the more parallel alignment between $\theta_{\mathrm{B}}$ and $\theta_{\mathrm{NG}}$ at higher $N_{\mathrm{H_2}}$ is because the magnetic field line is dragged by gravity. At even higher $N_{\mathrm{H_2}}$, the angle between $\theta_{\mathrm{B}}$ and $\theta_{\mathrm{NG}}$ or $\theta_{\mathrm{LG}}$ transits back to having no preferred orientation or statistically slightly more perpendicular, suggesting that the magnetic field structure is impacted by star formation activities. A statistically more perpendicular alignment is found between $\theta_{\mathrm{B}}$ and $\theta_{\mathrm{VG}}$ throughout our studied $N_{\mathrm{H_2}}$ range, which indicates a trans-to-sub-Alfv\'{e}nic state at small scales as well. The normalised mass-to-flux ratio derived from the polarization-intensity gradient (KTH) method increases with $N_{\mathrm{H_2}}$.Comment: 35 pages, 18 figures. Accepted by Ap

Intervention effects of Ganoderma lucidum spores on epileptiform discharge hippocampal neurons and expression of Neurotrophin-4 and N-Cadherin

Epilepsy can cause cerebral transient dysfunctions. Ganoderma lucidum spores (GLS), a traditional Chinese medicinal herb, has shown some antiepileptic effects in our previous studies. This was the first study of the effects of GLS on cultured primary hippocampal neurons, treated with Mg2+ free medium. This in vitro model of epileptiform discharge hippocampal neurons allowed us to investigate the anti-epileptic effects and mechanism of GLS activity. Primary hippocampal neurons from <1 day old rats were cultured and their morphologies observed under fluorescence microscope. Neurons were confirmed by immunofluorescent staining of neuron specific enolase (NSE). Sterile method for GLS generation was investigated and serial dilutions of GLS were used to test the maximum non-toxic concentration of GLS on hippocampal neurons. The optimized concentration of GLS of 0.122 mg/ml was identified and used for subsequent analysis. Using the in vitro model, hippocampal neurons were divided into 4 groups for subsequent treatment i) control, ii) model (incubated with Mg2+ free medium for 3 hours), iii) GLS group I (incubated with Mg2+ free medium containing GLS for 3 hours and replaced with normal medium and incubated for 6 hours) and iv) GLS group II (neurons incubated with Mg2+ free medium for 3 hours then replaced with a normal medium containing GLS for 6 hours). Neurotrophin-4 and N-Cadherin protein expression were detected using Western blot. The results showed that the number of normal hippocampal neurons increased and the morphologies of hippocampal neurons were well preserved after GLS treatment. Furthermore, the expression of neurotrophin-4 was significantly increased while the expression of N-Cadherin was decreased in the GLS treated group compared with the model group. This data indicates that GLS may protect hippocampal neurons by promoting neurotrophin-4 expression and inhibiting N-Cadherin expression