Flux Ratio Research Articles

Chemistry in Externally FUV-irradiated Disks in the Outskirts of the Orion Nebula Cluster

Most stars are born in stellar clusters, and their protoplanetary disks, which are the birthplaces of planets, can, therefore, be affected by the radiation of nearby massive stars. However, little is known about the chemistry of externally irradiated disks, including whether or not their properties are similar to the so-far better-studied isolated disks. Motivated by this question, we present ALMA Band 6 observations of two irradiated Class II protoplanetary disks in the outskirts of the Orion Nebula Cluster to explore the chemical composition of disks exposed to (external) far-ultraviolet (FUV) radiation fields: the 216-0939 disk and the binary system 253-1536A/B, which are exposed to radiation fields of 102–103 times the average interstellar radiation field. We detect lines from CO isotopologues, HCN, H2CO, and C2H toward both protoplanetary disks. Based on the observed disk-integrated line fluxes and flux ratios, we do not find significant differences between isolated and irradiated disks. The observed differences seem to be more closely related to the different stellar masses than to the external radiation field. This suggests that these disks are far enough away from the massive Trapezium stars, that their chemistry is no longer affected by external FUV radiation. Additional observations toward lower-mass disks and disks closer to the massive Trapezium stars are required to elucidate the level of external radiation required to make an impact on the chemistry of planet formation in different kinds of disks.

Effect of Inlet Geometry on Film-Cooling Effectiveness from Shaped Holes

Modern gas turbine engines require a sophisticated cooling system design to achieve higher power output and efficiency. This study investigates the potential effect of noncylindrical inlet geometries on the performance of laid-back, fan-shaped film-cooling holes using the pressure-sensitive paint measurement technique on a flat plate. On the basis of a common pattern of outlet geometry, racetrack-shaped inlet geometries with aspect ratios of 2:1 and 4:1 were tested along with traditional cylindrical inlets. The coolant flow conditions range from M = 0.3–1.5 and DR = 1 and 2. The mainstream turbulence intensity is held at 6%. Test results show that the shaped inlets provide a higher area-averaged film-cooling effectiveness over the cylindrical inlet using the same amount of coolant. For the 2:1 inlet, an advantage of 20% higher effectiveness could be maintained for DR = 1, while for DR = 2 this advantage is reduced to 10%. For the 4:1 inlet, when the coolant momentum flux ratio I < 0.5, a similar or slightly higher improvement can be obtained, but when I > 1, the advantage diminishes with the growing I to approximately 5%, at I = 2.25. Regarding discharge coefficients, the 2:1 inlet geometry is similar to the cylindrical inlet. For the 4:1 inlet, it is 2–5% lower or nearly equivalent.

Reverse Shock Revisited in Cassiopeia A with Chandra

Using data from the Chandra X-ray Observatory, we revisit the reverse shock in the supernova remnant (SNR) Cassiopeia A. Based on spectroscopy of a series of annuli in the northwest (NW) and southeast (SE), we get the radial profiles of the S/Si Kα line flux ratio and Fe Kα line centroid energy. They both show monotonic increase, confirming that the Si- and Fe-rich ejecta are heated by the reverse shock. The abrupt change of the S and Si line flux ratio is clearly observed in Cassiopeia A, leading to the determination of the reverse-shock location (∼1.′71 ± 0.′16 and ∼1.′35 ± 0.′18 in the NW and SE, with respect to the central source). By comparing the radial profiles of the S and Si line flux, we find that the reverse shock is moving outward in the frame of the observer, and the velocities are ∼3950 ± 210 km s−1 and ∼2900 ± 260 km s−1 in the NW and SE, respectively. In contrast, the velocities become ∼1150 km s−1 (NW) and ∼1300 km s−1 (SE) in the ejecta frame. Our measured reverse-shock velocities are quite consistent with those obtained from the X-ray and/or optical images. They therefore supply a cross-check of the accuracy for the two available methods for measuring the reverse-shock velocity in SNRs. Both the location and the velocity of the reverse shock show apparent asymmetry, suggesting that the asymmetric explosion of the progenitor plays a key role in the interaction between the reverse shock and the ejecta, ultimately shaping the complex features observed in SNRs.

Experimental study on the penetration and evaporation characteristics of a liquid kerosene jet in the supersonic crossflow

The penetration and evaporation characteristics of a liquid kerosene jet in the supersonic crossflow were experimentally investigated in this study. The experiments were carried out in both cold and high-enthalpy inflows. Detailed spray images were obtained using planar laser scattering techniques. The structures of the spray field were further analyzed on the basis of high spatial and temporal resolution images. The results show that the atomization and evaporation characteristics of a liquid kerosene jet are related to the crossflow temperature, liquid–gas momentum flux ratio, and injection distance. It is found that the breakup process of a liquid jet is accelerated in the high-enthalpy inflow. To accurately describe the maximum flow distance along the direction that kerosene can reach in the state of droplets, the survival distance is defined. It is revealed that the penetration depth and survival distance of the liquid kerosene jet decrease clearly with increase in the crossflow temperature. For the cavity-based combustor, the liquid kerosene jet can mix more sufficiently in the cavity region by reducing the injection distance and liquid–gas momentum flux ratio.

Flow characteristics and propulsive performance of oblique detonation waves induced by a transverse jet

The initiation of oblique detonation waves (ODWs) is a key component of the successful application of oblique detonation wave engines (ODWEs). This paper numerically investigates the initiation of ODWs under the active control of a transverse jet by solving the two-dimensional multi-species Euler equations, focusing on the morphology of the flow fields as well as the relationship between the flow structures and propulsive performance using the concept of thrust potential. Active jet control significantly shortens the initiation length of the ODW. The results reveal that the jet-induced flow field shows four typical patterns depending on the jet momentum flux ratio and wedge angle: shock-induced combustion, a type I pattern, a type II pattern, and a type I-II pattern. For the jet-induced ODW flow field, the propulsive performance declines as the momentum flux ratio increases when the wedge angle is certain. The larger the wedge angle, the greater the magnitude of the decline. The thrust of the flow field consists of two main components: the thrust generated by the mixture that passes first through the oblique shock wave and then through the detonation wave, and the thrust generated by the mixture that passes directly through the ODW front. Since the ODW upstream front has a larger wave angle, the flow loss of the mixture passes through the ODW upstream front is higher and the thrust potential is lower. This work could guide the active control of the initiation of ODWs at low flow losses.

Comprehensive spatiotemporal evaluation of urban growth, surface urban heat island, and urban thermal conditions on Java island of Indonesia and implications for urban planning

Urban heat island (UHI) and thermal comfort conditions are among the impacts of urbanization, which have been extensively studied in most cities around the world. However, the comprehensive studies in Indonesia in the context of urbanization is still lacking. This study aimed to classify land use and land cover (LULC) and analyse urban growth and its effects on surface urban heat islands (SUHIs) and urban thermal conditions as well as contributing factors to SUHI intensity (SUHII) using remote sensing in the western part of Java Island and three focused urban areas: the Jakarta metropolitan area (JMA), the Bandung and Cimahi Municipalities (BC), and the Sukabumi Municipality (SKB). Landsat imagery from three years was used: 2000, 2009, and 2019. Three types of daytime SUHII were quantified, namely the SUHII of urban central area and two SUHIIs of urban sprawl area. In the last two decades, urban areas have grown by more than twice in JMA and SKB and nearly 1.5 times in BC. Along with the growth of the three cities, the SUHII in the urban central area has almost reached a magnitude of 6 °C in the last decade. Rates of land surface temperature change of the unchanged urban pixels have magnitudes of 0.25, 0.15, and 0.14 °C/year in JMA, SKB, and BC, respectively. The urban thermal field variance index (UTFVI) and discomfort index (DI) showed that the strongest SUHI effect was most prevalent in urban pixels and the regions were mostly in the very hot and hot categories. Anthropogenic heat flux and urban ratio have positive contributions to SUHII variation, while vegetation and water ratios are negative contributors to SUHII variation. For each city, the contributing factors have a unique magnitude that can be used to evaluate SUHII mitigation options.

Strain distribution in the active region of InAs-based interband cascade laser

Energy-dispersive x-ray spectroscopy and high-angle annular dark-field in a Cs-corrected scanning transmission electron microscope are employed to characterize the atomic-scale strain distribution in the active region of the InAs-based interband cascade laser. For the first time, energy-dispersive x-ray spectroscopy is utilized for the quantitative calculation of the zero-strain region, by which the geometric phase analysis of high-angle annular dark-field imaging has been carried out. The strain distribution of the active region with high accuracy has been obtained. The analysis of the out-of-plane strain shows that the active region in the InAs-based interband cascade laser is strain-compensated, while a certain degree of elemental intermixing still exists in the active region. This detailed strain distribution can provide valuable insights into the optimization of the growth conditions for the active region such as growth temperature, V/III flux ratio, and growth process to minimize the elemental intermixing and obtain a better performance interface while maintaining the strain-compensated state.

Role of Surface Energy Fluxes in Urban Overheating Under Buoyancy‐Driven Atmospheric Conditions

AbstractUrbanization alters land surface properties in absorbing, reflecting and emitting radiation as well as infiltrating, evaporating and storing water. This consequently modifies surface energy and water fluxes and, thus, urban climates. Weak synoptic flow, clear sky conditions and higher surface temperatures in cities compared to their rural surroundings create a buoyancy‐driven atmospheric circulation, in which surface energy fluxes become the main determinants of urban daytime overheating. Here, we demonstrate the role of surface energy fluxes for warming and cooling processes in the urban canopy layer under buoyancy‐driven atmospheric conditions. We improve and apply an integrated CFD‐GIS modeling approach to provide a detailed analysis of fine‐scale land‐atmosphere interactions and assess the surfaces' profound implications on energy and water exchange. We show that variations in the ratios of the surface energy fluxes to the net radiation can be separated from meteorological conditions (wind speed, air temperature and incoming solar radiation) and emissivity values, varying explicitly with changes in land surface type and water availability for vegetated areas. Based on the energy flux ratios, we introduce an approach to assess the surface‐induced warming and cooling effect and its contribution to urban overheating in the urban canopy layer, under buoyancy‐driven atmospheric conditions, directly applicable to strategic urban planning for climate change adaptation. Independent of meteorological conditions, this approach can be used to evaluate different surface materials (both natural and artificial) and climate adaptation measures, such as urban nature‐based solutions and blue‐green infrastructures, and to monitor changes in the energy and water balance.

Properties of Cosmic Deuterons Measured by the Alpha Magnetic Spectrometer.

Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of the deuteron (D) flux are presented. The measurements are based on 21×10^{6} D nuclei in the rigidity range from 1.9 to 21GV collected from May 2011 to April 2021. We observe that over the entire rigidity range the D flux exhibits nearly identical time variations with the p, ^{3}He, and ^{4}He fluxes. Above 4.5GV, the D/^{4}He flux ratio is time independent and its rigidity dependence is well described by a single power law ∝R^{Δ} with Δ_{D/^{4}He}=-0.108±0.005. This is in contrast with the ^{3}He/^{4}He flux ratio for which we find Δ_{^{3}He/^{4}He}=-0.289±0.003. Above ∼13 GV we find a nearly identical rigidity dependence of the D and p fluxes with a D/p flux ratio of 0.027±0.001. These unexpected observations indicate that cosmic deuterons have a sizable primarylike component. With a method independent of cosmic ray propagation, we obtain the primary component of the D flux equal to 9.4±0.5% of the ^{4}He flux and the secondary component of the D flux equal to 58±5% of the ^{3}He flux.

Helium in Exoplanet Exospheres: Orbital and Stellar Influences

Searches for helium in the exospheres of exoplanets via the metastable near-infrared triplet have yielded 17 detections and 40 nondetections. We performed a comprehensive reanalysis of published studies to investigate the influence of stellar X-ray and extreme-ultraviolet (XUV) flux and orbital parameters on the detectability of helium in exoplanetary atmospheres. We identified a distinct “orbital sweet spot” for helium detection, 0.03 to 0.08 au from the host star, where the majority of detections occurred. This sweet spot is influenced by the stellar luminosity and planet size. Notably, a lower ratio of XUV flux to mid-UV flux is preferred for planets compared to nondetections. We also found that helium detections occur for planets around stars with effective temperatures of 4400–6500 K (i.e., spectral type K and G stars), with a sharp gap between 5400 and 6000 K, where no detections occur. We also report an upper-limit efficiency of 6% for energy-limited atmospheric escape from our analysis. Additionally, our analysis of the cumulative XUV flux versus escape velocity shows planets with helium detections above the “cosmic shoreline,” where atmospheres are not thought to be present, suggesting the shoreline needs revision. The unexpected trends revealed in our meta-analysis can contribute to a better understanding of star–planet interaction and exosphere evolution.

A NIRCam-dark Galaxy Detected with the MIRI/F1000W Filter in the MIDIS/JADES Hubble Ultra Deep Field

We report the discovery of Cerberus, an extremely red object detected with the MIRI Deep Imaging Survey (MIDIS) observations in the F1000W filter of the Hubble Ultra Deep Field. The object is detected at signal-to-noise ratio (S/N) ∼ 6, with F1000W ∼ 27 mag, and undetected in the NIRCam data gathered by the JWST Advanced Deep Extragalactic Survey (JADES), fainter than the 30.0–30.5 mag 5σ detection limits in individual bands, as well as in the MIDIS F560W ultradeep data (∼29 mag, 5σ). Analyzing the spectral energy distribution built with low-S/N (<5) measurements in individual optical-to-mid-infrared filters and higher-S/N (≳5) measurements in stacked NIRCam data, we discuss the possible nature of this red NIRCam-dark source using a battery of codes. We discard the possibility of Cerberus being a solar system body based on the <0.″016 proper motion in the 1 yr apart JADES and MIDIS observations. A substellar Galactic nature is deemed unlikely, given that the Cerberus’s relatively flat NIRCam-to-NIRCam and very red NIRCam-to-MIRI flux ratios are not consistent with any brown dwarf model. The extragalactic nature of Cerberus offers three possibilities: (1) a z ∼ 0.4 galaxy with strong emission from polycyclic aromatic hydrocarbons—the very low inferred stellar mass, M ⋆ = 105–106 M ⊙, makes this possibility highly improbable; (2) a dusty galaxy at z ∼ 4 with an inferred stellar mass M ⋆ ∼ 108 M ⊙; and (3) a galaxy with observational properties similar to those of the reddest little red dots discovered around z ∼ 7, but Cerberus lying at z ∼ 15, with the rest-frame optical dominated by emission from a dusty torus or a dusty starburst.

Numerical optimization of hydrothermal and thermodynamical performance for metal foam multi-jet impingement cooling

A novel porous multi-jet impingement cooling technology since the current conventional cooling technologies are insufficient for thermal engineering devices. This innovative numerical study explores the effect of various metal foam sizes (h/H), jet numbers (n) and wavy jet target plates (C) on the hydrothermal performance and thermodynamical performance at varying Reynolds numbers (Re). The novel results of multi-objective optimum design are a unique aspect of this work by combining the results of RSM with CFD, where low porosity (ε = 0.1), low applied heat flux (Q = 100 × 103 W/m2) and low location jet ratio (LRVin = 0.26) were achieved the aim of the optimum hydrothermal performance (NumP/NumS = 25-30 times and Tb Reduction% = 83.5%-89.5%) and the thermodynamical performance (EG Reduction% = 93%-96% and CoPCarnot = 2.3-6.5 times). Thus, a valuable procedure for the optimal design of the hydrothermal and thermodynamical performance for porous multi-jet impingement cooling is proposed.

First observation of edge impurity behavior with n = 1 RMP application in EAST L-mode plasma

High-Z impurity accumulation suppression and mitigation in core plasma is frequently observed in EAST edge localized mode mitigation experiments by using resonant magnetic perturbations (RMP) coils. To study the individual effects of the RMP field on impurity transport, based on high-performance extreme ultraviolet impurity spectroscopic diagnostics, the effect of the n = 1 (n is the toroidal mode number) RMP field on the behavior of intrinsic impurity ions at the plasma edge, e.g. He+, Li2+, C2+–C5+, O5+, Fe8+, Fe15+, Fe17+, Fe22+, Cu17+, Mo12+, Mo13+ and W27+, is analyzed for the first time in L-mode discharges. Based on the evaluation of the location of these impurity ions, it is found that with the increase in RMP current (I RMP), an impurity screening layer inside the last closed flux surface is formed, e.g. at ρ = 0.74–0.96, which is also the region that the RMP field affects. Outside this screening layer, the impurity ion flux of He+, Li2+, C2+, C3+, O5+, Fe8+, Mo12+ and Mo13+ ions increases gradually, while inside this screening layer, the impurity ion flux of C4+, C5+, Cu17+, W27+, Fe15+, Fe17+ and Fe22+ ions decreases gradually. When I RMP is higher than a threshold value, RMP field penetration occurs, accompanied with m/n = 2/1 mode locking, and the position of this screening layer moves to the plasma core region, i.e. ρ = 0.66–0.76, close to the q = 2 surface, and the opposite behavior of the impurity ion flux at two sides of the screening layer is strengthened dramatically. As a result, significant decontamination effects in the plasma core region, indicated by the factor of ((Γ Imp Z+)w/o–(Γ Imp Z+))/(Γ Imp Z+)w/o (where (Γ Imp Z+)/(Γ Imp Z+)w/o denotes the impurity ion flux ratio with and without RMP), is observed, i.e. 30%–60% for heavy impurity (Fe, Cu, Mo, W), and ∼27% for light impurity of C. In addition, the analysis of the decontamination effects of C and Fe impurities under four different RMP phase configurations shows that it may be related to the strength of the response of the plasma to RMP. These results enhance the understanding of impurity accumulation suppression by the n = 1 RMP field and demonstrate a candidate approach using RMP coils for W control in magnetic confinement devices.

Numerical Study of Pressure Response to Action Potential by Water Permeation With Ion Transports

Abstract While the permeation mechanism of solute (e.g., ions and glucose) through biological membrane has been studied extensively, the mechanical role of water transport in intracellular phenomena has not received much attention. In the present study, to investigate the effect of water permeation on the intracellular pressure response, a novel permeation flux model through a biological membrane is developed by incorporating the coupling permeabilities (between water and ion fluxes) as the water–ion interaction in the ion channels. The proposed model is applied to a two–dimensional permeation problem of water and ions in a closed cell separated by a thin membrane. The permeation flux model reproduces the typical time response of intracellular pressure to action potentials with reasonable agreement with experimental results in the literature, indicating that the pressure response can be characterized by the following three parameters: water permeability, the mass ratio of water and ion, and the ratio of the permeation fluxes of water and ion. In particular, the permeation flux ratio plays an essential role in intracellular phenomena; depending on the value of the permeation flux ratio, the time lag between the action potential and the pressure response is 0.1 times smaller than that expected by the previous researchers, indicating that water transport associated with ions may trigger a pressure response. This study demonstrates the importance of water permeation in intracellular mechanical response through coupling of the fluid motion and electric fields.

Fabrication of high aspect ratio AlN nanopillars by top-down approach combining plasma etching and wet etching

This study proposes a top-down approach for fabricating high aspect ratio AlN pillars with m-oriented nonpolar sidewalls, which will serve as the first building block for the fabrication of core-shell UV-LEDs. Such structures are achieved through a two-step process, combining a chlorine plasma etching, followed by a wet chemical etching with KOH. In this work, the mechanisms driving the AlN etching in chlorine plasma are discussed. In particular, we highlight the impact of the ratio between ion flux and radical flux on AlN etch rates, pillar profiles, and crystal orientation-dependent etching. We also identify two mechanisms of passivation layer formation on the pillar sidewalls that contribute to the pattern slope: redeposition of the carrier wafer etch by-products and Aluminium line of sight redeposition, both phenomena are also driven by the ionic bombardment. Low ionic bombardment (either low ion over radical flux ratio or low ion energy) has been identified as plasma conditions allowing the patterning of anisotropic AlN pillars but with the formation of a-nonpolar facets. Due to the inability to obtain m-oriented sidewalls using Cl2 plasma etching alone, we show that the use of a KOH wet etching treatment allows verticalizing the pillars and revealing smooth m-facets on the pillars’ sidewalls if suitable m-oriented hard mask is used. In this wet etching step, we highlight the key role played by the hard mask and its initial shape during the wet etching if straight and m-oriented pillars are desired.

Flux effect on defect evolution in uranium dioxide under electronic and ballistic regimes

The microstructure evolution of ion-irradiated UO2 was evaluated by in situ Raman spectroscopy. Transmission electron microscopy (TEM) was also conducted for selected irradiation conditions. The UO2 samples were irradiated with single- (900 keV I ions) or dual-ion beams (900 keV I and 27 MeV Fe or 36 MeV W ions) with different ratios between the high- and low-velocity ion flux (R). The analysis of the damage build-up shows that the electronic excitations deposited by the high-velocity ions affect the formation and evolution of defects induced by nuclear energy loss. In addition, the kinetics of dislocation evolution are more advanced when the flux ratio promotes electronic excitations. Consequently, a higher R value favors electronic excitations, leading to greater microstructural evolution.

FABRICATION AND CHARACTERIZATION OF POLYETHERSULFONE (PES) MEMBRANES BY BLENDING POLYMERS FOR REMOVAL OF ORGANIC COMPOUNDS IN AIR

The PES membrane was modified using a polymer blending method to improve the performance and characteristics of the membrane. This research aims to see the effect of adding biosilica additives on the performance characteristics of PES membranes and determine the optimal composition of additives and solvents for making membranes. The membrane was made using the Non-solvent Induced Phase Separation (NIPS) method with a composition consisting of 18% PES, with the addition of varying concentrations of silica (1%, 2%, 3%, and 4%) and the membrane using the solvent N-Methyl- 2 Pyrrolidone (NMP) and Dimethyl Sulfoxide (DMSO). Membrane characterization was carried out by observing membrane morphology using Scanning Electron Microscopy (SEM), membrane surface functional group analysis test using Fourier Tranform Infrared (FTIR), membrane porosity test using the dry-wet weight procedure method, the highest porosity value was found on membrane B2 using a solvent DMSO with 2% silica is 16.88%. Membrane performance was carried out by pure water flux testing, the highest pure water flux value was found in membrane B2 with 2% silica, namely 64.14 L/m2.h. The antifouling test uses flux ratio recovery, the highest antifouling value is found on the A3 membrane with 3% silica, namely 91.3%. As well as rejection of the humic acid solution as a Natural Organic Matter (NOM) sample model using the ultrafiltration (UF) module with a dead end filtration flow system, the highest rejection value was found on the B2 membrane with 2% silica, namely 64.4%.

Calculating torque, back-EMF, inductance, and unbalanced magnetic force for a hybrid electrical vehicle by in-wheel drive application

To use a Hybrid Excitation Synchronous Machine (HESM) in a hybrid electrical vehicle (HEV), its performance indicators such as back-EMF, inductance and unbalanced magnetic force should be computed preferably by an analytical method. First, the back-EMF is calculated by considering alternate-teeth and all-teeth non-overlapping and overlapping windings. The effects of three types of magnetization patterns including the radial, parallel and Halbach magnetizations on the back-EMF waveform have also been investigated. Then, the self-inductance of the stator and rotor windings, the mutual inductance between the stator and rotor windings, and the mutual inductance between the stator phases are computed. Next, the components of the unbalanced magnetic force (UMF) in the direction of the x and y axes and its amplitude are computed. Moreover, the effects of the magnetization patterns on those magnetic pulls are investigated. To minimize the UMFs, symmetry must be implemented in the excitation sources; therefore, first the stator winding then the permanent magnet and rotor winding are modified in such a way that the UMFs are reduced. Increasing the temperature leads to a weakening of the magnet’s residual flux density, which strongly affects the performance characteristics of the electric machine such as Back-EMF and UMF. Finally, the ratio of the permanent magnet flux to the rotor flux is determined in such a way that the average torque is maximized. In this section, the effects of three magnetization patterns will be investigated.

Enhancement of antifouling and mechanical properties of polysulfone membrane using zwitterionic biphenyl polyimide as additive

Biphenyl polyimides, which are known by its excellent heat resistance and mechanical properties, were synthesized by adjusting the molar ratio of monomers, followed by end-functionalized with zwitterionic group via reaction with 1,3-propanesultone. The zwitterionic sulfobetaine biphenyl polyimide (z-biph-PI) copolymers with different hydrophobic chain lengths were employed as the additive for the preparation of polysulfone (PSf) membrane. X-ray photoelectron spectrometry (XPS) measurement on membrane surfaces revealed that the sulfobetaine groups of z-biph-PI migrated toward water in the membrane formation process, during which a large amount of porous, narrow and densely packed pores were created as illustrated in scanning electron microscopy (SEM) images. Therefore, the incorporation of z-biph-PI simultaneously enhanced the pure water flux and protein rejection ratio of membranes, overcoming the trade-off effects between permeability and selectivity. The adsorption of bovine serum albumin decreased from ∼47.7 μg/cm2 for the pristine membrane to a minimum of ∼12.4 μg/cm2 for the blend membrane. More importantly, the tensile strength and elongation at break were also simultaneously improved due to the unique mechanical property of biph-PI and the strong π-π interaction between biphe-PI and PSf. Meanwhile, the blend membrane exhibited excellent filtration and thermal stability. All these characteristics of the blend membrane made it promising in ultrafiltration application.

Phase-resolved XMM-Newton observations of the massive post-RLOF system HD 149404

Context. We investigated the X-ray emission of HD 149404, a 9.81-day period O-star binary in a post-Roche lobe overflow evolutionary stage. X-ray emission of O-star binaries consists of the intrinsic emission of the individual O stars and a putative additional component arising from the wind-wind interaction. Aims. Phase-locked variations in the X-ray spectra can be used to probe the properties of the stellar winds of such systems. Methods. XMM–Newton observations of HD 149404 collected at two conjunction phases and a quadrature phase were analysed. X-ray spectra were extracted and flux variations as a function of orbital phase were inferred. The flux ratios were analysed with models considering various origins for the X-ray emission. Results. The highest and lowest X-ray fluxes are observed at conjunction phases respectively with the primary and secondary star in front. The flux variations are nearly grey with only marginal energy dependence. None of the models accounting for photoelectric absorption by homogeneous stellar winds perfectly reproduces the observed variations. Whilst the overall X-ray luminosity is consistent with a pure intrinsic emission, the best formal agreement with the observed variations is obtained with a model assuming pure windwind collision X-ray emission. Conclusions. The lack of significant energy-dependence of the opacity most likely hints at the presence of optically thick clumps in the winds of HD149404.