In recent studies, we proposed that source properties of type II radio bursts can be inferred through a causal relationship between the special shape of the type II dynamic spectrum (e.g., bump or ...break) and simultaneous extreme ultraviolet (EUV)/white light imaging observations (e.g., CME-shock crossing streamer structures). As a further extension of these studies, in this paper we examine the coronal mass ejection (CME) event on 2007 December 31 associated with a multiple type II radio burst. We identify the presence of two spectral bump features on the observed dynamic spectrum. By combining observational analyses of the radio spectral observations and the EUV-white light imaging data, we conclude that the two spectral bumps result from a CME-shock propagating across dense streamers on the southern and northern sides of the CME. It is inferred that the corresponding two type II emissions originate separately from the two CME-shock flanks where the shock geometries are likely quasi-perpendicular or oblique. Since the emission lanes are bumped as a whole within a relatively short time, it suggests that the type II radio bursts with bumps of this study are emitted from spatially confined sources (with a projected lateral dimension smaller than 0.05-0.1 R sub(middot in circle) at a fundamental frequency level of 20-30 MHz).
Context. The importance of magnetic fields at the onset of star formation related to the early fragmentation and collapse processes is largely unexplored today. Aims. We want to understand the ...magnetic field properties at the earliest evolutionary stages of high-mass star formation. Methods. The Atacama Large Millimeter Array is used at 1.3 mm wavelength in full polarization mode to study the polarized emission, and, using this, the magnetic field morphologies and strengths of the high-mass starless region IRDC 18310-4. Results. Polarized emission is clearly detected in four sub-cores of the region; in general it shows a smooth distribution, also along elongated cores. Estimating the magnetic field strength via the Davis-Chandrasekhar-Fermi method and following a structure function analysis, we find comparably large magnetic field strengths between ~0.3–5.3 mG. Comparing the data to spectral line observations, the turbulent-to-magnetic energy ratio is low, indicating that turbulence does not significantly contribute to the stability of the gas clump. A mass-to-flux ratio around the critical value 1.0 – depending on column density – indicates that the region starts to collapse, which is consistent with the previous spectral line analysis of the region. Conclusions. While this high-mass region is collapsing and thus at the verge of star formation, the high magnetic field values and the smooth spatial structure indicate that the magnetic field is important for the fragmentation and collapse process. This single case study can only be the starting point for larger sample studies of magnetic fields at the onset of star formation.
ABSTRACT
Infrared dark clouds (IRDCs) are potential hosts of the elusive early phases of high mass star formation (HMSF). Here, we conduct an in-depth analysis of the fragmentation properties of a ...sample of 10 IRDCs, which have been highlighted as some of the best candidates to study HMSF within the Milky Way. To do so, we have obtained a set of large mosaics covering these IRDCs with Atacama Large Millimeter/submillimeter Array (ALMA) at Band 3 (or 3 mm). These observations have a high angular resolution (∼3 arcsec; ∼0.05 pc), and high continuum and spectral line sensitivity (∼0.15 mJy beam−1 and ∼0.2 K per 0.1 km s−1 channel at the N2H+ (1 − 0) transition). From the dust continuum emission, we identify 96 cores ranging from low to high mass (M = 3.4−50.9 M⊙) that are gravitationally bound (αvir = 0.3−1.3) and which would require magnetic field strengths of B = 0.3−1.0 mG to be in virial equilibrium. We combine these results with a homogenized catalogue of literature cores to recover the hierarchical structure within these clouds over four orders of magnitude in spatial scale (0.01–10 pc). Using supplementary observations at an even higher angular resolution, we find that the smallest fragments (<0.02 pc) within this hierarchy do not currently have the mass and/or the density required to form high-mass stars. None the less, the new ALMA observations presented in this paper have facilitated the identification of 19 (6 quiescent and 13 star-forming) cores that retain >16 M⊙ without further fragmentation. These high-mass cores contain trans-sonic non-thermal motions, are kinematically sub-virial, and require moderate magnetic field strengths for support against collapse. The identification of these potential sites of HMSF represents a key step in allowing us to test the predictions from high-mass star and cluster formation theories.
Our previous study showed there was a change of microRNA (miRNA) expression profile, and miR-21 was significantly down regulated in insulin-resistant adipocytes (IR-adipocytes). Phosphatase and ...tensin homologs deleted on chromosome 10 (PTEN), a negative regulator of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, was identified to be a target gene of miR-21, which suggested miR-21 might be associated with insulin resistance (IR) or diabetes. However, it is not known whether miR-21 play any role in the development of IR in 3T3-L1 adipocytes.
Normal adipocytes and adipocytes transfected with pre-miR-21(pmiR-21) or negative control (pNeg) were treated with high glucose and high insulin for 24 h, insulin-stimulated glucose uptake was determined by 2-Deoxyglucose transport assay, miR-21 expression level was measured by using quantitative real-time RT-PCR (qRT-PCR). The protein expression levels of PTEN, Akt, phospho-Akt (Ser473), IRβ, GSK3β, phospho-GSK3β (Ser9) and GLUT4 were detected by western blotting assay.
We further confirmed that miR-21 was down regulated in IR-adipocytes by qRT-PCR. Over-expression of miR-21 significantly increased insulin-induced glucose uptake and decreased PTEN protein expression, while it had no significant effect on PTEN mRNA expression in IR-adipocytes. Moreover, over-expressing miR-21 significantly increased insulin-induced phosphorylation of AKT (Ser473), GSK3β (Ser9) and the translocation of glucose transporter 4 (GLUT4) in IR-adipocytes.
In this study, our data demonstrate that miR-21 reverses high glucose and high insulin induced IR in 3T3-L1 adipocytes, possibly through modulating the PTEN-AKT pathway, and miR-21 may be a new therapeutic target for metabolic diseases such as T2DM and obesity.
In this Account we describe the hydrothermal synthesis of some new materials including microporous crystals, ionic conductors, complex oxides and fluorides, low-dimensional aluminophosphates, ...inorganic-organic hybrid materials, and particularly condensed materials such as diamond and inorganic helical chains. Hydrothermal synthesis in biology and environment sciences is also introduced. The increasing interest in hydrothemal synthesis derives from its advantages in terms of high reactivity of reactants, easy control of solution or interface reactions, formation of metastable and unique condensed phases, less air pollution, and low energy consumption.
The study of hot corinos in solar-like protostars has been so far mostly limited to the Class 0 phase, hampering our understanding of their origin and evolution. In addition, recent evidence suggests ...that planet formation starts already during Class I phase, which therefore represents a crucial step in the future planetary system chemical composition. Hence, the study of hot corinos in Class I protostars has become of paramount importance. Here, we report the discovery of a hot corino towards the prototypical Class I protostar L1551 IRS5, obtained within the ALMA (Atacama Large Millimeter/submillimeter Array) Large Program FAUST (Fifty AU STudy of the chemistry in the disc/envelope system of solar-like protostars). We detected several lines from methanol and its isotopologues (13CH3OH and CH2DOH), methyl formate, and ethanol. Lines are bright towards the north component of the IRS5 binary system, and a possible second hot corino may be associated with the south component. The methanol lines' non-LTE analysis constrains the gas temperature (∼100 K), density (≥1.5 × 10^8 per cu.cm), and emitting size (∼10 au in radius). All CH3OH and 13CH3OH lines are optically thick, preventing a reliable measure of the deuteration. The methyl formate and ethanol relative abundances are compatible with those measured in Class 0 hot corinos. Thus, based on this work, little chemical evolution from Class 0 to I hot corinos occurs.
•A systematic review of predictors of spinal anesthesia-induced hypotension.•Blood volume/fluid responsiveness may predict spinal anesthesia-induced hypotension.•Supine stress tests may optimize the ...predictive value of static state predictors.•Autonomic nervous system and peripheral perfusion index were not reliable.•Maternal demographics and baseline hemodynamic parameters were not useful.
Spinal anesthesia is the standard for elective cesarean section but spinal anesthesia-induced hypotension remains an important problem. Accurate prediction of hypotension could enhance clinical decision-making, alter management, and facilitate early intervention. We performed a systematic review of predictors of spinal anesthesia-induced hypotension and their predictive value during cesarean section.
PubMed, Embase, Cochrane Library, Google Scholar and Web of Science databases were searched for prospective observational studies assessing the diagnostic accuracy of predictors of spinal anesthesia-induced hypotension in elective cesarean section. The quality of studies was assessed and predictors were grouped in domains based on the type of predictor.
Thirty-eight studies (n=3086 patients) were included. In most studies, patients received 500–1000 mL crystalloid preload or 500–2000 mL crystalloid coload. Vasopressors for post-spinal hypotension were boluses of ephedrine 5–15 mg and/or phenylephrine 25–100 µg in most studies. The hypotension rate varied from 29% to 80% based on the definition. For analysis, >30 predictors were classified into seven domains: demographic characteristics, baseline hemodynamic variables, baseline sympathovagal balance, postural stress testing, peripheral perfusion indices, blood volume and fluid responsiveness indices, and genetic polymorphism.
Environmental and individual factors increased outcome variability, which restricted the value of the autonomic nervous system and peripheral perfusion indices for prediction of spinal anesthesia-induced hypotension. Supine stress tests may reflect parturients’ cardiovascular tolerance during hemodynamic fluctuations and may optimize the predictive value of static state predictors. Future research for predicting spinal anesthesia-induced hypotension should focus on composite and dynamic parameters during the supine stress tests.
Spray dry technique was applied to produce paclitaxel loaded microspheres of biodegradable poly (lactic-co-glycolic acid) (PLGA) as an alternative delivery system. Various emulsifiers such as
...l-α-dipalmitoyl-phosphatidylcholine (DPPC), cholesterol, polyvinyl alcohol (PVA), gelatin were incorporated in order to achieve high encapsulating efficiency of paclitaxel in the microspheres and desired properties for a sustained release. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed that the surface of the microspheres with high ratio of lipid was spherical and smooth. Those made with other emulsifiers had rougher surface with pores. Incorporation of lipid, cholesterol or gelatin can significantly increase the drug content in the microspheres. The differential scanning calorimetry (DSC) result indicated that the paclitaxel trapped in the microspheres existed in an amorphous or disordered-crystalline status in the polymer matrix. The zeta potential of the microspheres was negative in general and was strongly influenced by the type of the emulsifiers used in fabrication. The system formulated with cholesterol was most stable. The release profiles of various formulations with PVA, gelatin as well as low ratio of DPPC showed almost zero-order release kinetics in the first 3 weeks after an initial burst less than 5% in the first day. The release rate then gradually decreased. The microspheres fabricated with high ratio of DPPC exhibited large initial burst. When cholesterol was combined together with DPPC as an emulsifier, the release became faster.
Abstract
We present sensitive NH
3
(1,1)–(7,7) line images from the Karl G. Jansky Very Large Array toward successive shocks, which are associated with the blueshifted outflow lobe driven by the ...compact protobinary system L1157. Within a projection distance of 0.1 pc, our observations not only trace the quiescent and cold gas in the flattened envelope, but also illustrate the complex physical and chemical processes that take place where the high-velocity jet impinges on its surrounding medium. Specifically, the NH
3
ortho-to-para ratio is enhanced by a factor of 2–2.5 along the jet path, where the velocity offset between the line peak and the blueshifted wing reaches values as high as 10 km s
−1
; it also shows a strong spatial correlation with the NH
3
column density, which is enhanced to >10
16
cm
−2
toward the shock cavities. At a linear resolution of 1500 au, our refined temperature map from the seven NH
3
lines shows a gradient from the warm B0 eastern cavity wall (>120 K) to the cool cavity B1 and the earlier shock B2 (<80 K), indicating shock heating.
Two new phenoxo-bridged heterobimetallic Zn(II)
2
M(II) (M = Sr and Ba) salamo-based complexes, {Zn(L)(μ
2
-OAc)}
2
Sr·0.33CH
3
OH·H
2
O (
1
) and {Zn(L)(μ
2
-OAc)}
2
Ba (
2
), have been designed, ...self-assembled and characterized by elemental analysis, FT-IR and UV-Vis spectroscopy, X-ray crystallography, Hirshfeld surfaces analyses, and Density Functional Theory (DFT) calculations. The results of UV and fluorescence titration experiments have demonstrated that the coordination ratio of the ligand H
2
L to Zn(II) has been 1 : 2 in the L–Zn(II) precursor. However, X-ray crystallographic analysis indicates the coordination ratio of H
2
L to Zn(II) as 1 : 1 in the complexes
1
and
2
. Coordination environments of the complexes
1
and
2
are almost similar. The complex
1
has an asymmetric heterotrinuclear structure, while the complex
2
is formed as the symmetric heterotrinuclear structure. Fluorescence spectra demonstrate that fluorescence of the ligand is almost completely quenched due to coordination of Zn(II) atoms with H
2
L. According to DFT calculations chemical stability of the complexes
1
and
2
is higher than that of H
2
L.
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