A feedback-driven bubble G24.136+00.436: a possible site of triggered star formation

We present a multi-wavelength study of the IR bubble G24.136+00.436. The J=1-0 observations of $^{12}$CO, $^{13}$CO and C$^{18}$O were carried out with the Purple Mountain Observatory 13.7 m telescope. Molecular gas with a velocity of 94.8 km s$^{-1}$ is found prominently in the southeast of the bubble, shaping as a shell with a total mass of $\sim2\times10^{4}$ $M_{\odot}$. It is likely assembled during the expansion of the bubble. The expanding shell consists of six dense cores. Their dense (a few of $10^{3}$ cm$^{-3}$) and massive (a few of $10^{3}$ $M_{\odot}$) characteristics coupled with the broad linewidths ($>$ 2.5 km s$^{-1}$) suggest they are promising sites of forming high-mass stars or clusters. This could be further consolidated by the detection of compact HII regions in Cores A and E. We tentatively identified and classified 63 candidate YSOs based on the \emph{Spitzer} and UKIDSS data. They are found to be dominantly distributed in regions with strong emission of molecular gas, indicative of active star formation especially in the shell. The HII region inside the bubble is mainly ionized by a $\sim$O8V star(s), of the dynamical age $\sim$1.6 Myr. The enhanced number of candidate YSOs and secondary star formation in the shell as well as time scales involved, indicate a possible scenario of triggering star formation, signified by the "collect and collapse" process.Comment: 13 pages, 10 figures, 4 tables, accepted by Ap

The Impact of Extrinsic Amino Acids and Solvent Fractionation on the in vitro Antioxidant Activity of Plastein Reaction-Stressed Casein Hydrolysates

Za pripremu hidrolizata kazeina stupnja hidrolize od 9,4 % upotrijebljen je enzim papain. Dobiveni je hidrolizat imao in vitro antioksidativnu aktivnost tj. sposobnost uklanjanja DPPH radikala od 38,7 % i EC50 vrijednost od 1,63 mg/mL. Dodatkom fenilalanina ili tirozina potaknuta je plastein reakcija katalizirana pomoću papaina. Metodom odzivnih površina optimirani su sljedeći parametri pri vremenu reakcije od 5 h: temperatura od 30 °C, koncentracija supstrata od 50 % (m/V), udjel enzima od 3 kU/g peptida i udjel aminokiselina od 0,74 mol/mol slobodnih aminokiselinskih grupa hidrolizata. Pripremljeno je nekoliko modificiranih hidrolizata, te je ispitana njihova antioksidativna aktivnost, i to sposobnost uklanjanja DPPH radikala i reducirajuća snaga. Dobiveni su rezultati pokazali da su svi modificirani hidrolizati imali znatno veću sposobnost uklanjanja radikala (p<0,05) i reducirajuću snagu od izvornih hidrolizata, a među njima je bio i jedan s najnižom EC50 vrijednosti od 1,09 mg/mL. Frakcioniranjem modificiranog hidrolizata najveće antioksidativne aktivnosti pomoću etanola i vode u omjerima od 3:7, 4:6, 5:5 i 6:4 dobiveni su supernatanti ili precipitati veće ili manje antioksidativne aktivnosti i reducirajuće snage, naročito pomoću otapala male polarnosti (npr. omjera etanola i vode od 6:4). Supernatanti s najvećom aktivnošću imali su EC50 vrijednost od 0,69 mg/mL. Rezultati pokazuju da se dodatkom fenilalanina ili tirozina u plastein reakciji hidrolizata kazeina te daljnjim frakcioniranjem otapalom mogu dobiti modificirani hidrolizati veće antioksidativne aktivnosti.Papain was used to prepare a casein hydrolysate with a degree of hydrolysis of 9.4 %. The hydrolysate had the in vitro antioxidant activity with a DPPH radical scavenging activity of 38.7 % and an EC50 of 1.63 mg/mL. Extrinsic phenylalanine or tyrosine was added to the hydrolysate for a papain-catalyzed plastein reaction. The temperature, substrate mass per volume fraction, and the levels of enzyme and amino acid addition during the reaction were optimized using response surface methodology with a fixed reaction time of 5 h, and were found to be 30 °C, 50 %, 3 kU per g of peptides and 0.74 mol per mol of the free amino groups of the hydrolysate, respectively. Some modified hydrolysates were prepared and their antioxidant activity was evaluated in terms of DPPH radical scavenging activity and reducing power. The results revealed that all prepared modified hydrolysates had significantly higher (p<0.05) scavenging activity and reducing power than the original hydrolysate, and among them one showed the lowest EC50 of 1.09 mg/mL against DPPH radical. When the modified hydrolysate with the highest activity was fractionated using ethanol/water solvents in volume ratios of 3:7, 4:6, 5:5 and 6:4, the supernatant or precipitate fraction exhibited an enhanced or decreased activity or reducing power, especially with the solvent of lower polarity (e.g. 6:4 by volume). The obtained supernatant with the highest activity thus exhibited an EC50 of 0.69 mg/mL. The results show that extrinsic phenylalanine or tyrosine addition in the plastein reaction of casein hydrolysate and further solvent fractionation of the modified hydrolysate is applicable to improve the antioxidant properties of products

Interactions of the Infrared bubble N4 with the surroundings

The physical mechanisms that induce the transformation of a certain mass of gas in new stars are far from being well understood. Infrared bubbles associated with HII regions have been considered to be good samples of investigating triggered star formation. In this paper we report on the investigation of the dust properties of the infrared bubble N4 around the HII region G11.898+0.747, analyzing its interaction with its surroundings and star formation histories therein, with the aim of determining the possibility of star formation triggered by the expansion of the bubble. Using Herschel PACS and SPIRE images with a wide wavelength coverage, we reveal the dust properties over the entire bubble. Meanwhile, we are able to identify six dust clumps surrounding the bubble, with a mean size of 0.50 pc, temperature of about 22 K, mean column density of 1.7 $\times10^{22}$ cm$^{-2}$, mean volume density of about 4.4 $\times10^{4}$ cm$^{-3}$, and a mean mass of 320 $M_{\odot}$. In addition, from PAH emission seen at 8 $\mu$m, free-free emission detected at 20 cm and a probability density function in special regions, we could identify clear signatures of the influence of the HII region on the surroundings. There are hints of star formation, though further investigation is required to demonstrate that N4 is the triggering source.Comment: Accepted by ApJ (16 pages, 11 figures, 9 tables

Physical properties and chemical composition of the cores in the California molecular cloud

We aim to reveal the physical properties and chemical composition of the cores in the California molecular cloud (CMC), so as to better understand the initial conditions of star formation. We made a high-resolution column density map (18.2") with Herschel data, and extracted a complete sample of the cores in the CMC with the \textsl{fellwalker} algorithm. We performed new single-pointing observations of molecular lines near 90 GHz with the IRAM 30m telescope along the main filament of the CMC. In addition, we also performed a numerical modeling of chemical evolution for the cores under the physical conditions. We extracted 300 cores, of which 33 are protostellar and 267 are starless cores. About 51\% (137 of 267) of the starless cores are prestellar cores. Three cores have the potential to evolve into high-mass stars. The prestellar core mass function (CMF) can be well fit by a log-normal form. The high-mass end of the prestellar CMF shows a power-law form with an index $\alpha=-0.9\pm 0.1$ that is shallower than that of the Galactic field stellar mass function. Combining the mass transformation efficiency ($\varepsilon$) from the prestellar core to the star of $15\pm 1\%$ and the core formation efficiency (CFE) of 5.5\%, we suggest an overall star formation efficiency of about 1\% in the CMC. In the single-pointing observations with the IRAM 30m telescope, we find that 6 cores show blue-skewed profile, while 4 cores show red-skewed profile. [$\rm {HCO}^{+}$]/[HNC] and [$\rm {HCO}^{+}$]/$\rm [N_{2}H^{+}]$ in protostellar cores are higher than those in prestellar cores; this can be used as chemical clocks. The best-fit chemical age of the cores with line observations is $\sim 5\times 10^4$~years.Comment: Accepted by Astronomy & Astrophysics (A&A

Exclusive real-time monitoring during recurrent laryngeal nerve dissection in conventional monitored thyroidectomy

Abstract During conventional intermittent intraoperative neuromonitoring (IONM) in thyroidectomy, recurrent laryngeal nerve (RLN) injury is detected by an electromyographic (EMG) loss of signal (LOS) after the nerve dissection. Exclusive continuous monitoring during the phase of RLN dissection may be helpful in detecting adverse EMG changes earlier. A total of 208 RLNs at risk were enrolled in this study. Standardized IONM procedures were followed. We continuously stimulated the RLN at the lower exposed end with a stimulator to exclusively monitor the real-time quantitative EMG change during RLN dissection. Once the amplitude decreased by more than 50% of the initial signal, the surgical maneuver was paused and the RLN was retested every minute for 10 minutes to determine amplitude recovery before restarting the dissection. The procedure was feasible in all patients. No LOS was encountered in this study. Nineteen RLNs had an amplitude reduction of more than 50%. Eighteen nerves showed gradual amplitude recovery (16 nerves had a traction injury and two nerves had a compression injury). After 10 minutes, the recovery was complete (i.e., >90%) in eight nerves, 70–90% in seven nerves, and 50–70% in three nerves. Among these 18 nerves, only one nerve developed temporary vocal palsy because it was exposed to unavoidable repeated nerve traction after restarting the dissection. Another nerve showed no gradual recovery from thermal injury, and developed temporary vocal palsy. The temporary and permanent palsy rates were 1% and 0%, respectively. During intermittent IONM, exclusive real-time monitoring of the RLN during dissection is an effective procedure to detect an adverse EMG change, and prevent severe RLN injuries that cause LOS

Food Markets with Live Birds as Source of Avian Influenza

A patient may have been infected with highly pathogenic avian influenza virus H5N1 in Guangzhou, People's Republic of China, at a food market that had live birds. Virus genes were detected in 1 of 79 wire cages for birds at 9 markets. One of 110 persons in the poultry business at markets had neutralizing antibody against H5N1.link_to_subscribed_fulltex

Brown Carbon Aerosol in Urban Xi’an, Northwest China: TheComposition and Light Absorption Properties

Light-absorbing organic carbon (i.e., brown carbon or BrC) in the atmospheric aerosol has significant contribution to light absorption and radiative forcing. However, the link between BrC optical properties and chemical composition remains poorly constrained. In this study, we combine spectrophotometric measurements and chemical analyses of BrC samples collected from July 2008 to June 2009 in urban Xi&#39;an, Northwest China. Elevated BrC was observed in winter (5 times higher than in summer), largely due to increased emissions from wintertime domestic biomass burning. The light absorption coefficient of methanol-soluble BrC at 365 nm (on average approximately twice that of water-soluble BrC) was found to correlate strongly with both parent polycyclic aromatic hydrocarbons (parent-PAHs, 27 species) and their carbonyl oxygenated derivatives (carbonyl-OPAHs, 15 species) in all seasons (r(2) &gt; 0.61). These measured parent-PAHs and carbonyl-OPAHs account for on average similar to 1.7% of the overall absorption of methanol-soluble BrC, about 5 times higher than their mass fraction in total organic carbon (OC, similar to 0.35%). The fractional solar absorption by BrC relative to element carbon (EC) in the ultraviolet range (300-400 nm) is significant during winter (42 +/- 18% for water-soluble BrC and 76 +/- 29% for methanol-soluble BrC), which may greatly affect the radiative balance and tropospheric photochemistry and therefore the climate and air quality