Flux Attenuation Research Articles

Statistical analysis of the association between El Niño and the biological carbon pump in the East Sea (Japan Sea)

Understanding the impacts of climate change on oceanic carbon cycling is important from a carbon sequestration perspective. A sediment trap study focused on the biological carbon pump system in the Ulleung Basin (UB) in the southwestern part of the East Sea (Japan Sea) was conducted from 2011 to 2017. Particulate organic carbon (POC) flux significantly increased by 37, 56, and 43% from 2014 to 2016 during the El Niño phase. We examined data related to water current variability, such as sea surface height, current velocity, and eddy frequency to understand their roles in particle transport. In addition, a Martin curve was employed to analyze the rate of vertical attenuation of POC flux in the UB. Current variability could be the most important factor influencing the increase in sinking-particle flux during the El Niño phase.

Photopolymerization enabled in-air highly oleophobic and hydrophilic SiC membranes with improved antifouling performance in oil-in-water emulsion separation

Ceramic membranes with tailored surface wettability have gained increasing attention for improving their separation efficiency and antifouling ability, while most of the previous work focused on the underwater oleophobic behavior. In this work, in-air highly oleophobic and hydrophilic SiC membranes were achieved through the UV irradiation triggered polymerization and controlled crosslinking between oleophobic perfluorodecyl acrylate (TFOA) and hydrophilic methacrylic acid (MAA). These key processing parameters including MAA content, soaking time and irradiation duration were systematically studied through examining the changes in porous microstructure, surface wettability and separation performance in oil-in-water emulsion. Results showed that the flux attenuation rate of SiC membranes can be effectively reduced by regulating the content of hydrophilic components. Due to the alternation of the surface wettability to highly oleophobic in air, the oil droplets can hardly attach on the surface of modified SiC membranes at the beginning of filtration process, and the membrane fouling was significantly slow down yet dominated by the intermediate blocking. Correspondingly, a combined cleaning procedure was proposed to regenerate the fouled SiC membranes. Further, the antifouling ability of modified and original SiC membranes was comparatively studied under the conditions of a fixed permeate volume (15 ml) and various oil concentrations (200 ∼ 1000 ppm) in the separation of oil-in-water emulsion. The advantages of modified SiC membranes become more notable when used for highly concentrated oil–water emulsion as reflected by the slower flux decline and higher stable flux. This work provides a feasible pathway to realize the in-air highly oleophobic and hydrophilic surface on ceramic membranes, and primarily demonstrates the advantages of antifouling ability in oil-in-water emulsion separation.

Thioredoxin-interacting protein (TXNIP) is a substrate of the NEDD4-like E3 ubiquitin-protein ligase WWP1 in cellular redox state regulation of acute myeloid leukemia cells.

The HECT-type E3 ubiquitin WWP1 (also known as NEDD4-like E3 ubiquitin-protein ligase WWP1) acts as an oncogenic factor in acute myeloid leukemia (AML) cells. WWP1 overexpression in AML confers a proliferative advantage to leukemic blasts (abnormal immature white bloodcells) and counteracts apoptotic cell death and differentiation. In aneffort to elucidate the molecular basis of WWP1 oncogenic activities, we identified WWP1 as a previously unknown negative regulator of thioredoxin-interacting protein (TXNIP)-mediated reactive oxygen species (ROS) production in AML cells. TXNIP inhibits the disulfide reductase enzymatic activity of thioredoxin (Trx), impairing its antioxidant function and, ultimately, leading to the disruption of cellular redox homeostasis. In addition, TXNIP restricts cell growth and survival by blocking glucose uptake and metabolism. Here, we found that WWP1 directly interacts with TXNIP, thus promoting its ubiquitin-dependent proteasomal proteolysis. As a result, accumulation of TXNIP in response to WWP1 inactivation inAML blasts reduces Trx activity and increases ROS production, henceinducing cellular oxidative stress. Increased ROS generation in WWP1-depleted cells culminates in DNA strand breaks and subsequent apoptosis. Coherently with TXNIP stabilization following WWP1 inactivation, we also observed an impairment of both glucose up-take and consumption. Hence, a contribution to the increased cell death observed in WWP1-depleted cells also possibly arises from the attenuation of glucose up-take and glycolytic flux resulting from TXNIP accumulation. Future studies are needed to establish whether TXNIP-dependent deregulation of redox homeostasis in WWP1-overexpressing blasts may affect the response of leukemic cells to chemotherapeutic drugs.

Study the impact of spacer at thermal degradation process of MLI-based insulation in fire condition

To reduce CO2 emissions, energy carriers such as hydrogen are considered to be a solution. Consumption of hydrogen as a fuel meets several limitations such as its low volumetric energy density in gas phase. To tackle this problem, storage as well as transportation in liquified phase is recommended. To be able to handle this component in liquid phase, an efficient thermal insulation e.g., MLI insulation is required. Different studies have been addressed the vulnerability of such insulation against high thermal loads e.g., in an accident engaging fire. Some of research works have highlighted the importance of considering the MLI thermal degradation focusing on its reflective layer. However, limited number of studies addressed the thermal degradation of spacer material and its effect on the overall heat flux.In this study, through systematic experimental measurements, the effect of thermal loads on glass fleece, glass paper as well as polyester spacers are investigated. The results are reported in various temperature and heat flux profiles. Interpreting the temperature profiles revealed that, as the number of spacers in the medium increases, the peak temperature detectable by the temperature sensor on the measurement plate decreases. Each individual spacer contributes to mitigating the radiative energy received by the measurement plate. Stacks of 20–50 spacers (this is the number of layers in commercial MLI systems applied for liquid hydrogen applications) can potentially reduce the thermal radiation by 1–2 orders of magnitude.An empirical correlation to predict a heat flux attenuation factor is proposed, which is useful for further numerical and analytical studies in the temperature range from ambient to 300 °C.

In situ microbubble-mediated strategy for highly efficient anti-crude oil-fouling membrane with parallel nanosheet structure

Membrane fouling caused by highly viscous oils severely hampers the long-term application of oil–water separation membranes. In situ aeration, achieved by applying a voltage to the membrane to produce bubbles, can effectively reduce the adhesion of oil contaminants. Herein, the parallel NiFe-layered double hydroxide arrays were successfully constructed on Ni foam using a hydrothermal method. Compared with NF@NFLDH having randomly aligned nanosheet arrays, NF@NFLDH-P can produce more numerous micro-size bubbles. A substantial number of the microbubbles spontaneously coalesced with oil droplets, and the synergy of buoyancy and kinetic energy significantly hindered oil fouling on the NF@NFLDH-P membrane. Specifically, this microbubble–mediated anti-oil-fouling strategy substantially reduced the flux attenuation and maintained a high flux recovery ratio during long-term crude oil–water separation, exhibiting a great operational life. This study suggests an innovative way to design future anti-fouling membranes with bubble-mediated capabilities.

Decoding drivers of carbon flux attenuation in the oceanic biological pump

The biological pump supplies carbon to the oceans’ interior, driving long-term carbon sequestration and providing energy for deep-sea ecosystems1,2. Its efficiency is set by transformations of newly formed particles in the euphotic zone, followed by vertical flux attenuation via mesopelagic processes3. Depth attenuation of the particulate organic carbon (POC) flux is modulated by multiple processes involving zooplankton and/or microbes4,5. Nevertheless, it continues to be mainly parameterized using an empirically derived relationship, the ‘Martin curve’6. The derived power-law exponent is the standard metric used to compare flux attenuation patterns across oceanic provinces7,8. Here we present in situ experimental findings from C-RESPIRE9, a dual particle interceptor and incubator deployed at multiple mesopelagic depths, measuring microbially mediated POC flux attenuation. We find that across six contrasting oceanic regimes, representing a 30-fold range in POC flux, degradation by particle-attached microbes comprised 7–29 per cent of flux attenuation, implying a more influential role for zooplankton in flux attenuation. Microbial remineralization, normalized to POC flux, ranged by 20-fold across sites and depths, with the lowest rates at high POC fluxes. Vertical trends, of up to threefold changes, were linked to strong temperature gradients at low-latitude sites. In contrast, temperature played a lesser role at mid- and high-latitude sites, where vertical trends may be set jointly by particle biochemistry, fragmentation and microbial ecophysiology. This deconstruction of the Martin curve reveals the underpinning mechanisms that drive microbially mediated POC flux attenuation across oceanic provinces.

Roles of Earth’s Albedo Variations and Top-of-the-Atmosphere Energy Imbalance in Recent Warming: New Insights from Satellite and Surface Observations

Past studies have reported a decreasing planetary albedo and an increasing absorption of solar radiation by Earth since the early 1980s, and especially since 2000. This should have contributed to the observed surface warming. However, the magnitude of such solar contribution is presently unknown, and the question of whether or not an enhanced uptake of shortwave energy by the planet represents positive feedback to an initial warming induced by rising greenhouse-gas concentrations has not conclusively been answered. The IPCC 6th Assessment Report also did not properly assess this issue. Here, we quantify the effect of the observed albedo decrease on Earth’s Global Surface Air Temperature (GSAT) since 2000 using measurements by the Clouds and the Earth’s Radiant Energy System (CERES) project and a novel climate-sensitivity model derived from independent NASA planetary data by employing objective rules of calculus. Our analysis revealed that the observed decrease of planetary albedo along with reported variations of the Total Solar Irradiance (TSI) explain 100% of the global warming trend and 83% of the GSAT interannual variability as documented by six satellite- and ground-based monitoring systems over the past 24 years. Changes in Earth’s cloud albedo emerged as the dominant driver of GSAT, while TSI only played a marginal role. The new climate sensitivity model also helped us analyze the physical nature of the Earth’s Energy Imbalance (EEI) calculated as a difference between absorbed shortwave and outgoing longwave radiation at the top of the atmosphere. Observations and model calculations revealed that EEI results from a quasi-adiabatic attenuation of surface energy fluxes traveling through a field of decreasing air pressure with altitude. In other words, the adiabatic dissipation of thermal kinetic energy in ascending air parcels gives rise to an apparent EEI, which does not represent “heat trapping” by increasing atmospheric greenhouse gases as currently assumed. We provide numerical evidence that the observed EEI has been misinterpreted as a source of energy gain by the Earth system on multidecadal time scales.

Ligand Shell Thickness of PEGylated Gold Nanoparticles Controls Cellular Uptake and Radiation Enhancement.

The drive to improve the safety and efficacy of radiotherapies for cancers has prompted the development of nanomaterials that can locally amplify the radiation dose at a tumor without damaging the surrounding healthy tissue. Gold nanoparticles (Au NPs), in particular, exhibit promising radiosensitizing properties under kilovolt X-ray exposure, although the precise mechanism behind this enhancement is not fully understood. While most studies recognize the involvement of factors such as core composition, size, shape, and ligand chemistry in the effectiveness of Au NPs for radiation-induced cancer treatment, there is a scarcity of direct assessments that connect the photophysical properties of the nanomaterial with the observed cellular or biological outcomes. Despite previous evidence of low-energy electron (LEE) emission from Au NPs and their potential to initiate biological damage, to our knowledge, no studies directly correlate the secondary LEE emission with radiation-induced cell death. In this study we assessed Au NPs functionalized with polyethylene glycol (PEG) ligands of varying molecular weights and lengths (1, 5, and 20 kDa PEG) as potential radiosensitizers of A549 lung cancer cells using kilovolt X-ray source potentials (33-130 kVp). We assessed NP internalization using mass cytometry, radiation dose enhancement using clonogenic survival assays, and secondary LEE emission using a retarding field analyzer. Results reveal a statistically significant difference in cellular uptake and radiation dose enhancement for 5 kDa PEG-Au NPs compared to formulations using 1 and 20 kDa PEG, while analysis of secondary LEE emission spectra demonstrated that differences in the length of the PEG ligand did not cause statistically significant attenuation of secondary LEE flux. Consequently, we inferred increased cellular uptake of NPs to be the cause for the observed enhancement in radiosensitivity for 5 kDa PEGylated Au NPs. The approach used in this study establishes a more complete workflow for designing and characterizing the performance of nanomaterial radiosensitizers, allowing for quantification of secondary LEEs and cellular uptake, and ultimately correlation with localized dose enhancement that leads to cell death.

Effect of environmentally friendly reverse osmosis scale inhibitors on inorganic calcium carbonate scale

A highly efficient and environmentally friendly composite scale inhibitor was developed using sodium carboxymethyl cellulose (CMC-Na) and polyepoxysuccinic acid (PESA). The PESA:CMC-Na=1:3 optimum ratio was observed with a maximum enhancement factor of 1.81. The film flux attenuation rate was reduced from 24.98 % to 6.2 % at optimal operational condition (concentration 80 mg/L, initial pH 7) for actual mine water treatment. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis results showed that the addition of the compound scale inhibitor transformed the calcium carbonate scale from calcite to vaterite with looser and more porous structure. The molecular dynamics simulation results demonstrate that composite scale inhibitor had a higher binding energy with calcite than that of PESA, CMC-Na, resulting in the restrained formation of calcite. This study provides a new technical idea for the application of scale inhibitor to improve the treatment efficiency of mine water by reverse osmosis.

Near-field radiative heat transfer between graphene-covered Weyl semimetals

Polariton manipulations introduce novel approaches to modulate the near-field radiative heat transfer (NFRHT). Our theoretical investigation in this study centers on NFRHT in graphene-covered Weyl semimetals (WSMs). Our findings indicate variable heat flux enhancement or attenuation, contingent on chemical potential of graphene. Enhancement or attenuation mechanisms stem from the coupling or decoupling of surface plasmon polaritons (SPPs) in the graphene/WSM heterostructure. The graphene-covered WSM photon tunneling probabilities variation is demonstrated in detail. This research enhances our comprehension of SPPs within the graphene/WSM heterostructure and suggests methods for actively controlling NFRHT.

Interaction of Cosmic Rays With Magnetic Flux Ropes

AbstractThe heliosphere is full of galactic cosmic rays (GCR), high‐energy charged particles coming isotropically from the galaxy. The GCR interact with the solar wind blown by the Sun carrying out plasma, magnetic fields and transient structures such as interplanetary coronal mass ejections (ICMEs) and their associated magnetic flux ropes (MFR). The GCR interaction with ICMEs has been extensively studied particularly the GCR flux attenuation (known as Forbush decreases) as a result of interacting with the ICME sheath and magnetic field. In this work, we investigate the opposite effect: the MFR's ability to generate GCR anisotropies which an observer may detect as an increase in the GCR flux. To achieve this, we simulated a flux of protons with energies in the 10–160 GeV range arriving from all directions to a cylindrical MFR (with and without sheath) with plasma, magnetic field, and spatial dimensions found in average ICMEs observed at 1 au. By following the individual trajectories of the injected particles we found that the MFR deviates the charged particles preferentially in one direction parallel to the MFR–axis. We also found that the peak of this anisotropic GCR flux depends on: the angle between the MFR and ambient magnetic fields; the presence or not of the sheath region; the energy of the incident particles and the observer location inside the MFR.

Impact of aggregate‐colonizing copepods on the biological carbon pump in a high‐latitude fjord

AbstractZooplankton consumption of sinking aggregates affects the quality and quantity of organic carbon exported to the deep ocean. Increasing laboratory evidence shows that small particle‐associated copepods impact the flux attenuation by feeding on sinking particles, but this has not been quantified in situ. We investigated the impact of an abundant particle‐colonizing copepod, Microsetella norvegica, on the attenuation of the vertical carbon flux in a sub‐Arctic fjord. This study combines field measurements of vertical carbon flux, abundance, and size‐distribution of marine snow and degradation rates of fecal pellets and algal aggregates. Female M. norvegica altered their feeding behavior when exposed to aggregates, and ingestion rates were 0.20 μg C ind.−1 d−1 on marine snow and 0.11 μg C ind.−1 d−1 on intact krill fecal pellets, corresponding to 48% and 26% of the females' body carbon mass. Due to high sea surface abundance of up to ~ 50 ind. L−1, the population of M. norvegica had the potential to account for almost all the carbon removal in the upper 50 m of the water column, depending on the type of the aggregate. Our observations highlight the potential importance of abundant small‐sized copepods for biogeochemical cycles through their impact on export flux and its attenuation in the twilight zone.

Synergistically controlling biofouling and improving membrane module permeability by using simultaneously structurally optimized and surface modified feed spacers

This study developed a new protocol to prepare feed spacers in the membrane module, by combining the optimization of spacers' geometrical parameters with subsequent chemical modification of the spacers’ surface, to enhance filtration performance comprehensively. Geometrical parameters of columnar spacers were optimized using an object-oriented and automatic optimization method based on computational fluid dynamics (CFD) simulation coupled with response surface optimization. In chemical modification, polydopamine was firstly used to provide anti-adhesive properties, followed by the even integration of silver nanoparticles (AgNPs) to exhibit antimicrobial activity. Anti-biofouling experiments involving Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria demonstrated that the combined structurally optimized and chemically modified spacers resulted in over 10 % improvement in permeate flux and a 27 % reduction in feed channel pressure (FCP) drop. Chemical modification enhanced the structural optimization resistance to flux attenuation and FCP drop increase by over 220 % and 200 %, respectively. Analysis of the anti-biofouling behavior indicated that the primary mechanism of the integrated, optimized spacers lies in the increased wall shear, bactericidal activity of AgNPs, and improved interfacial interaction energy between the spacers and foulants. This study not only developed a novel modification method for anti-biofouling spacers, but also provides in-depth understanding of the roles of modified spacers, all of which are important for their practical applications in improving membrane filtration performance.

Influence of cosmic voids on the propagation of TeV gamma-rays and the puzzle of GRB 221009A

ABSTRACT The recent detection of gamma-ray burst GRB 221009A has attracted attention due to its record brightness and first-ever detection of $\gtrsim 10$ TeV gamma-rays from a GRB. Despite being the second-nearest GRB ever detected, at a redshift of $z=0.151$, the distance is large enough for severe attenuation of gamma-ray flux at these energies due to $\gamma \gamma \rightarrow e^\pm$ pair production with the extragalactic background light (EBL). Here, we investigate whether the presence of cosmic voids along the line of sight can significantly impact the detectability of very high energy (VHE, $\gt $100 GeV) gamma-rays from distant sources. Notably, we find that the gamma–gamma opacity for VHE gamma-rays can be reduced by approximately 10 per cent and up to 30 per cent at around 13 TeV, the highest-energy photon detected from GRB 221009A, for intervening cosmic voids along the line of sight with a combined radius of 110 Mpc, typically found from void catalogues, and 250 Mpc, respectively. This reduction is substantially higher for TeV photons compared to GeV photons, attributable to the broader target photon spectrum that TeV photons interact with. This finding implies that VHE photons are more susceptible to variations in the EBL spectrum, especially in regions dominated by cosmic voids. Our study sheds light on the detection of $\gtrsim 10$ TeV gamma-rays from GRB 221009A in particular, and on the detection of extragalactic VHE sources in general.

On the detailed mapping of peat (raised bogs) using airborne radiometric data

This study concerns the applied use of the natural radioactivity in soils. The relevance of airborne radiometric (gamma ray) survey data to peat mapping is now well established and such data have been used in a stand-alone sense and as covariates in machine learning algorithms. Here we present a method to use these data to accurately map the boundaries of peat (raised bogs). This has the potential to assist with the estimation of carbon stocks using a property-based assessment of soil. The significance of such regionally-uniform survey data lies in the subsurface information carried by the measurement which contrasts with the surficial nature of many other covariates. Soils attenuate radiometric flux by virtue of their bulk density (and associated carbon content) and water saturation level. The high attenuation levels in low density, wet peat materials give rise to a distinctive soil response. Here an entirely physics-based assessment of flux attenuation is carried out both theoretically and empirically. Radiometric data from the ongoing Tellus airborne survey of Ireland are used. The study area is characterised by an extensive assemblage of discrete raised peat bogs in a framework of largely mineral soils. Peat is detected by a property contrast with adjacent soils and so we consider all soils within the study area. The relatively low lateral resolution of the airborne data is demonstrated by modelling and we examine the behaviour of a combined spatial derivative of the data. The procedure allows the identification of the edges of the 128 peat polygons considered and indicates other additional potential areas of subsurface peat. The data appear to resolve the differences that exist across three available soil/peat databases that are used for the validation of the results obtained.

Preparation of high-flux polyethylene hollow fiber microfiltration membranes with multiple pore structure through the combination technology of braided tube reinforcement and TIPS method

Our team proposed the continuous preparation of the reinforced polyethylene (PE) hollow fiber microfiltration (MF) membranes based on the combination technology of braided tube reinforcement and thermally induced phase separation (TIPS) method. In this work, to improve the permeability and reduce the flux attenuation, we selected PE as the membrane-forming polymer, polyethylene glycol (PEG) and sodium chloride (NaCl) as the composite pore-forming agents to optimize the membrane-forming composition. In particular, the effect of NaCl contents on the permeation of the reinforced PE hollow fiber membranes was studied in detail. The reinforced PE hollow fiber MF membranes obtained the multiple pore structure containing small pores, large pores and cavity structure. The small pores were formed by PEG and white oil. The large pores and the cavity structure were formed by the discreted and agglomerated NaCl, respectively. The cavity structure provided the connectivity gaps for the small pores and forming an internal highly connected pathways, which could reduce the transmembrane resistance. Thus, the flux improved obviously with the increasing NaCl contents. When the NaCl content was 30 wt%, the pure water flux of the reinforced PE hollow fiber MF membranes could reach 1606.0 L·m−2 h−1 after pre-pressuring for 30 min. In addition, the reinforced PE hollow fiber MF membranes exhibited excellent tensile strength with 170.0 MPa and good corrosion resistance, which showed a great application potential in harsh environments. In particular, this method provides a new idea for the continuous preparation of the reinforced PE hollow fiber MF membranes.

Exploring the hardness of the ionising radiation with the infrared softness diagram

Aims. We explored the softness parameter in the infrared, ηIR′, whose main purpose is the characterisation of the hardness of the incident ionising radiation in emission-line nebulae. This parameter is obtained from the combination of mid-infrared wavelength range transitions corresponding to consecutive ionisation stages in star-forming regions. Methods. We compiled observational data from a sample of star-forming galaxies (SFGs), including luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs), to study the ηIR′ and its equivalent expression in two dimensions, the softness diagram. We compared them with predictions from photoionisation models to determine the shape of the ionising continuum energy distribution in each case. We also used the measured emission-line ratios as input for HCMISTRY-TEFF-IR, a code that performs a Bayesian-like comparison with photoionisation model predictions in order to quantify the equivalent effective temperature (T*) and the ionisation parameter. Results. We found similar average values within the errors of ηIR′ in (U)LIRGs (−0.57) in the rest of the SFGs (−0.51), which could be interpreted as indicative of a similar incident radiation field. This result is confirmed from the analysis using HCM-TEFF-IR, which simultaneously points to a slightly lower, although similar within the errors, T* scale for (U)LIRGs, even when a higher dust-to-gas mass ratio is considered in the models for these objects. These derived T* values are compatible with the ionisation from massive stars, without any need of harder ionising sources, both for (U)LIRGs and the rest of the SFGs. However, the derived T* in (U)LIRGs do not show any correlation with metallicity. This could be interpreted as a sign that their similar average T* values are due to the attenuation of the energetic incident flux from massive stars by the heated dust mixed with the gas. This is supported by the known very large amounts of small grains associated with the very high star formation rates measured in galaxies of this type.

Combination of membrane bioreactor with chemical coagulation for the treatment of real pharmaceutical wastewater: Comparison of simultaneous and consecutive pre-treatment of coagulation on MBR performance

In this work, the combination of the coagulation process with the MBR system to reclaim effluent in pharmaceutical industries was investigated. In this research, comparison/concentration optimization of two modes of integrations, including simultaneous; one-step one pot, and consecutive coagulation MBR were investigated. Results showed that COD removal in simultaneous and consecutive modes at optimum values were 85 % and 95.8 %, respectively, which were considerably higher than that of control MBR; 53.89 %. The total fouling ratio for control MBR, simultaneous, and consecutive modes at optimum conditions were 70.69 %, 37.3 %, and 42.5 %, respectively, confirming that the integrated coagulation process and MBR system were considerably effective. Analyzing the secreted metabolite, e.g. protein, carbohydrate, and LB/TB-EPS ratio in the MBR tank as well as on the membrane surface showed that the charge-neutralization and entrapment of bio-foulants by aggregated clots during the coagulation hinder the adhesion of the biofouling agents on the membrane surface, therefore in-line with the flux attenuation trend, lower metabolite concentration results in less membrane fouling. It was found that simultaneous coagulative MBR with 100 mg/L FeCl3 concentration demonstrates better fouling mitigation in comparison with consecutive (even with poly aluminum chloride; PACl as coagulant aid) MBR, while the latter mode shows better performance in terms of wastewater treatment. These findings open avenues for future techno-economic assessments of a coagulation-assisted MBR, providing a cost-effective solution for treating high-strength wastewater on a larger scale.

An observation-constrained estimation of brown carbon aerosol direct radiative effects

Abstract. Brown carbon (BrC) is an organic carbon component with noticeable absorption in the ultraviolet and short visible wavelengths, which influences the global radiative balance. However, assessing BrC radiative effects remains a challenging task owing to the scarcity of direct BrC observations and the uncertainties regarding their chemical and optical properties. This study proposes an efficient method for estimating BrC radiative effects based on the available observational data. The light-absorbing properties of BrC obtained from aethalometer measurements and an optical separation method were combined with simulated BrC optical properties to determine mass concentrations. An optical closure study was conducted to constrain the total and other aerosol contents. Subsequently, we estimated the aerosol optical properties and concentrations. Such a state-of-the-art combination of measurements and numerical models provides primary variables for simulating radiative transfer to estimate BrC radiative effects. We used observations conducted over 4 months (from 1 July to 18 November 2021) in Nanjing (a megacity in east China) as an example. During the observational period, BrC absorption constituted 8.7 %–34.1 % of the total aerosol absorption at 370 nm. In the atmosphere, BrC plays a warming role, with its average instantaneous radiative forcing (RF) and standard deviation of 4.0 ± 2.3 W m−2 corresponding to 15 ± 4.2 % of the black carbon (BC) RF. At the surface, the BrC-induced actinic flux (AF) attenuation is comparable to that caused by BC, accounting for over 55 % of the BC effects in the UV range and almost 20 % in the visible range. The photosynthetically active radiation (PAR) attenuated by BrC is approximately 33.5 ± 9.4 % of that attenuated by BC. Furthermore, we quantified the influences of several BC and BrC microphysical and optical properties on their radiative effects. These findings provide valuable insights for understanding BrC radiative effects. Moreover, they highlight the importance of and necessity for improved observation and modeling of BrC properties.

Neutron shielding calculation for DEMO-Prad/SXR measurement system

In plasma fusion devices, the selection of shielding materials is one of the challenges for plasma diagnostic and control systems under high radiation levels during long operation times. This study presents the effect of shielding materials on neutron flux for a radiated power and soft x-ray core intensity measurement system for a DEMOnstration power plant. A calculation model of neutron shielding was used to investigate the neutron shielding performance of borides and carbides for a large distance from plasma to the diagnostic system. The neutron fluxes were characterized for three points close to the measurement system location. The related neutronic calculations were performed with an ADVANTG hybrid code to obtain neutron flux distribution and attenuation rate depending on the thickness of shielding materials. The results indicate that B4C, W2B5, and WB4 are the most effective options to serve as shielding material due to the effect of boron on neutron shielding effectiveness.