Explore the vast range of titles available.

Recently, secondary organic aerosols (SOAs) generated from anthropogenic volatile organic compounds have been proposed as a possible source of light-absorbing organic compounds, \"brown carbon,\" in the urban atmosphere. However, the atmospheric importance of these SOAs remains unclear due to limited information about their optical properties. In this study, the complex refractive index (RI, m = n-ki values at 405, 532, and 781 nm of the SOAs generated during the photooxidation of toluene (toluene-SOAs) under a variety of initial nitrogen oxide (NOx = NO + NO2 ) conditions were examined by photoacoustic spectroscopy (PAS) and cavity ring-down spectroscopy (CRDS). The complex RI-values obtained in the present study and reported in the literature indicate that the k-value, which represents the light absorption of the toluene-SOAs, increased to shorter wavelengths at <532 nm, and the n-value also increased to shorter wavelengths from 781 to 355 nm. The k-values at 405 nm were found to increase from 0.0018 to 0.0072 with increasing initial NOx concentration from 109 to 571 ppbv. The nitrate to organics ratio of the SOAs determined using a high-resolution time-of-flight aerosol mass spectrometer (H-ToF-AMS) also increased with increasing initial NOx concentration. The RI-values of the SOAs generated during the photooxidation of 1,3,5-trimethylbenzene in the presence of NOx (1,3,5-TMB-SOAs) were also determined to investigate the influence of the chemical structure of the precursor on the optical properties of the SOAs, and it was found that the light absorption of the 1,3,5-TMB-SOAs is negligible at all of the wavelengths investigated (405, 532, and 781 nm). These results can be reasonably explained by the hypothesis that nitroaromatic compounds, such as nitrocresols, are the major contributors to the light absorption of the toluene-SOAs. Using the obtained RI-values, mass absorption cross sections of the toluene-SOAs at 405 nm were estimated to be 0.08-0.52 m2 g-1 under typical conditions in an urban atmosphere during the daytime. These results indicate that light absorption by the SOAs potentially contributes to the radiation balance at ultraviolet wavelengths below ~400 nm, specifically when the mass concentrations of the anthropogenic SOAs are significant compared with other light-absorbing particles.

This study investigates the potential impact of Solar Energetic Particles (SEPs) on the V0 layer of the Venus ionosphere. Electron density profiles obtained from radio occultation experiments conducted by the Venus Express (VEX) and Akatsuki missions were utilized for this purpose. Background data from the Analyzer of Space Plasma and EneRgetic Atoms (ASPERA‐4) aboard VEX were used to detect SEP events. Additionally, observations from the Space Environment Monitor (SEM) suite onboard the Geostationary Operational Environmental Satellite (GOES) during alignments of Venus, Earth, and the Sun were also considered. Our findings indicate that while SEPs may contribute to the formation of the V0 layer, they are not the main driving force in the Venusian ionosphere. Plain Language Summary The Venusian ionosphere shows sporadic enhancements in electron density around 110 km altitude. Despite extensive investigation, the exact cause of its sporadic presence remains elusive. Previous studies have explored various theories, including meteoric influences, gravity waves, and the impact of minor atmospheric constituents such as NO, O2, C, Ar, H2, and H. However, none have conclusively explained its formation mechanism. In this study, we have investigated the potential influence of Solar Energetic Particles (SEPs) on the V0 layer. By analyzing electron density profiles obtained from VEX/Akatsuki missions, hot plasma measurements by ASPERA‐4 onboard VEX, and SEM suite onboard GOES to identify SEP events, we surmise that while SEPs may contribute to the formation of the V0 layer, they are not the primary driving force in the Venusian ionosphere. Key Points The Impact of solar energetic particle (SEP) events on the formation of V0 layers in the Venusian ionosphere has been explored Enhanced ionization is seen above the V2 layer peak whenever a V0 layer seen in the Venus ionosphere SEPs and enhanced ionization at 110 km altitudes, however, are not correlated

The epithelial–mesenchymal transition (EMT) is a crucial morphological event that occurs during the progression of epithelial tumors. EMT can be induced by transforming growth factor β (TGF-β) in certain kinds of cancer cells through the induction of Snail, a key regulator of EMT. We have previously found that TGF-β remarkably induces Snail expression in cooperation with Ras signals; however, the underlying mechanism of this synergism has not yet been determined. Here, we demonstrate that signal transducer and activator of transcription 3 (STAT3) acts as a mediator that synergizes TGF-β and Ras signals. The overexpression of STAT3 enhanced Snail induction, whereas siRNA-mediated knockdown of STAT3 inhibited it. The STAT3-YF mutant, which has Tyr 705 substituted with Phe, did not enhance Snail induction. Several STAT3 mutants lacking transcriptional activity also failed to enhance it; however, the putative STAT3-binding elements in the Snail promoter regions were not required for STAT3-mediated Snail induction. Protein inhibitor of activated STAT3 (PIAS3) inhibited the enhanced Snail promoter activity induced by TGF-β and Ras. The interaction between PIAS3 and STAT3 was reduced by TGF-β in cells harboring oncogenic Ras, whereas TGF-β promoted the binding of PIAS3 to Smad3, a crucial mediator of TGF-β signaling. Therefore, these findings suggest that STAT3 enhances Snail induction when it is dissociated from PIAS3 by TGF-β in cooperation with Ras signals.

Using measurements from radio science experiments onboard Venus Express and Akatsuki orbiter, we explore factors that control the occurrence and spatial structure of the electron density enhancement at lower altitudes (V0 layer) in the Venus ionosphere. Results suggest that the Gravity Waves (GWs) play a crucial role in determining the shape of the V0 layer. For solar zenith angle (SZA) less than 40°, when the average gravity wave potential energy (AGPE) is less than 4.7 J/kg, V0 has a single well‐defined peak. For higher AGPE, the V0 peak height gets perturbed and exhibits a wave‐like structure. For SZA >40°, and AGPE >4.7 J/kg, mostly wave‐like feature at the base of the V0 layer emerges. We surmise that although GW do not control the formation of a V0 layer, they likely control its shape and occurrence altitude. Plain Language Summary Venus is known to have a peak in the plasma density at ∼140 km altitude (V2 layer), and a secondary permanent peak at ∼127 km (V1 layer). A sporadic enhancement in the electron density below 120 km altitude (now known as V0 layer) has also been reported. Earlier believed to be geographically localized, Akatsuki measurements have shown its presence over all the latitudes including at the deep equator during local noon hours. Though the origin of such enhancement in plasma density forming a V0 layer is still not clear, we have explored how the forcing from the lower atmosphere impacts the V0 layer characteristics. Our results suggest that the enhancement in the AGPE above a certain threshold value perturbs the plasma of the V0 layer and plays a pivotal role in defining its shape, but it does not impact the formation of this layer. We also observe the local time effect on the frequency of high AGPE leading to varying V0 layer features. Key Points The first study on the impact of gravity waves on the shape and characteristic features of V0 layers in the Venusian ionosphere Despite not necessarily being the cause of the V0 layer, gravity waves are seen as a crucial factor influencing its shape and structure A local time dependence on the structure of the V0 layer is also observed

Terrestrial exoplanets orbiting within or near their host stars’ habitable zone are potentially apt for life. It has been proposed that time-series measurements of reflected starlight from such planets will reveal their rotational period, main surface features and some atmospheric information. From imagery obtained with the Akatsuki spacecraft, here we show that Venus’ brightness at 283, 365, and 2020 nm is modulated by one or both of two periods of 3.7 and 4.6 days, and typical amplitudes  <10% but occasional events of 20–40%. The modulations are unrelated to the solid-body rotation; they are caused by planetary-scale waves superimposed on the super-rotating winds. Here we propose that two modulation periods whose ratio of large-to-small values is not an integer number imply the existence of an atmosphere if detected at an exoplanet, but it remains ambiguous whether the atmosphere is optically thin or thick, as for Earth or Venus respectively. Multi-wavelength and long temporal baseline observations may be required to decide between these scenarios. Ultimately, Venus represents a false positive for interpretations of brightness modulations of terrestrial exoplanets in terms of surface features. Establishing diagnostics for terrestrial exoplanets are crucial for their characterization. Here, the authors show brightness modulations of Venus are caused by planetary-scale waves superimposed on the super-rotating winds can be used to detect existence of an atmosphere if detected at an exoplanet.

Naoya Kataoka, Teruhiko ImamuraSecond Department of Internal Medicine, University of Toyama, Toyama, JapanCorrespondence: Teruhiko Imamura, Second Department of Internal Medicine, University of Toyama, 2630 Sugitani Toyama, Toyama, 930-0194, Japan, Tel +81-76-434-2281, Fax +81-76-434-5026, Email [email protected]View the original paper by Dr Cao and colleagues

Trans-coronal radio observations were taken during the 2011 observing campaign of the Akatsuki spacecraft through superior conjunction. The observed X-band (8.4 GHz) signals exhibit frequency fluctuations (FF) that are produced by temporal variations in electron density along the radio ray path. A two-component model for interpretation of the FF is proposed: FF scales largely with acoustic wave amplitude through the inner coronal regions where the sound speed dwarfs the solar wind outflow speed, while FF in the region of solar wind acceleration is dominated by the increased density oscillation frequency on the sensing path that results from bulk advection of the plasma inhomogeneities. An estimate of fractional electron density fluctuation is obtained from the mid-corona. A radial profile of slow solar wind speed is determined in the extended corona using mass-flux continuity principles. The coronal sonic point for slow solar wind is estimated to range from 4 to 5 solar radii from the heliocenter.

Transforming growth factor (TGF)-β is known to promote tumor invasion and metastasis. Although bone morphogenetic proteins (BMPs), members of the TGF-β family, are expressed in a variety of human carcinoma cell lines, their roles in tumor progression have not been fully clarified. In this study, we sought to determine the roles of BMPs in the progression of breast cancer bone metastasis using human breast cancer samples and a mouse xenograft model. Immunohistochemical analysis of samples from breast cancer patients as well as a mouse xenograft model of MDA-231-D, highly metastatic human breast cancer cells, revealed phospho-Smad2 and phospho-Smad1/5/8 staining in the nuclei of cancer cells in primary tumor and/or bone metastasis. Using a functional in vivo bioluminescence imaging system, we showed that TGF-β- and BMP-induced transcriptional pathways are active in bone metastatic lesions in vivo . In addition, both TGF-β3 and BMP-2 promoted the motility and invasiveness of the MDA-231-D cells in vitro . Moreover, expression of dominant-negative receptors for TGF-β and/or BMPs in the MDA-231-D cells inhibited invasiveness in vitro and bone metastasis in the xenograft model. These results suggest that BMPs as well as TGF-β promote invasion and bone metastasis of breast cancer.

Oxygenated organic aerosol (OOA) observed in remote areas is believed to comprise aged secondary organic aerosol (SOA); however, the reaction processes relevant to SOA chemical aging have hitherto been unclear. We recently measured the mass spectra of SOA formed from the photooxidation of aromatic hydrocarbons using an Aerodyne aerosol mass spectrometer (AMS) and reported that SOA aging is slowed with increasing number of alkyl groups in the precursor molecule. In this study, we selected benzene and 1,3,5-trimethylbenzene (TMB) as precursors to analyze SOA formed from the photooxidation of aromatic hydrocarbons in the presence of NOx using high-resolution time-of-flight AMS (H-ToF-AMS) and liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS). A van Krevelen diagram was studied using the O/C and H/C ratios obtained by H-ToF-AMS for organics present in SOA. The results showed these organics to be rich in carboxylic acids or hydroxycarbonyls and the O/C ratio of SOA formed by the reaction of 1,3,5-TMB to be lower than that for benzene. Analytical results from LC/TOF-MS showed the particulate products formed by the reaction of 1,3,5-TMB to be richer in ketocarboxylic acids than for benzene. These results indicate that SOA aging proceeds mainly by formation of carboxylic acids and that the rate of SOA aging in laboratory chambers is limited by the oxidation of ketone groups. SOA formed in laboratory chamber experiments is less oxidized than for ambient OOA, not only because the experimental duration is insufficient or the SOA mass loading in the chamber is higher than that of the atmosphere. The laboratory chamber experiments under dry conditions are not able to simulate ketocarboxylic acid photochemical oxidation in the aqueous phase. The fractions of organic peroxides to the total SOA mass were determined by iodometric spectrophotometry to be 12 ± 8% (1,3,5-TMB) and <39% (benzene). Further, it was newly found that, unlike the reaction of benzene, only very small amounts of nitrophenols are produced by the reaction of 1,3,5-TMB.

3%Si-Fe sheet produced by high cold rolling reduction over 80% has strong {111} recrystallization texture. This orientation has two crystallographically equivalent orientations such as (111)[1 -2 1] and (111)[-1 -1 2]. However, there are a few previous works in which these orientations are investigated separately. In the present study, the recrystallization behavior of the crystallographically equivalent orientations of {111} was investigated using two samples with different grain sizes before cold rolling. Both recrystallized samples had strong {111} component texture. The sample with a small grain size before cold rolling had almost the same fraction of each equivalent orientations, while the sample with a large grain size had substantially different fractions of each equivalent orientations. Spatial distribution of two crystallographically equivalent orientations in the sample with a small grain size before cold rolling was almost homogeneous, however that in the sample with a large grain size before cold rolling was inhomogeneous. It is considered that these differences are explained by the assumption that a certain large grain before cold rolling will generate only single crystallographically equivalent orientation after cold rolling and annealing.