Air Exposure Research Articles

Effect of high-pressure torsion on first hydrogenation of Laves phase Ti0.5Zr0.5(Mn1-xFex)Cr1 (x = 0, 0.2 and 0.4) high entropy alloys

Laves phase high-entropy alloys are considered as good candidates for hydrogen storage applications. However, they usually suffer from poor first hydrogenation kinetics, the so-called activation process. In this paper, we attempt to solve the activation problem of the Ti0.5Zr0.5(Mn1-xFex)Cr1 (x = 0, 0.2 and 0.4) by high-pressure torsion (HPT). The HPT process was carried out under 6 GPa pressure for 5 revolutions in air on samples synthesized by arc melting. The hydrogenation kinetics were measured using a Sievert’s type apparatus at room temperature under 2 MPa of hydrogen pressure. While the as-cast alloys become totally inert to hydrogen after air exposure, the HPT-processed samples absorb 1.6–1.8 wt% of hydrogen at room temperature in a few seconds even after air exposure for 2 months. The easy activation of alloys processed by HPT is due to the formation of lattice defects that act as nucleation points. These results confirm that HPT processing is an effective strategy to develop active hydrogen storage materials.

Dietary fulvic acid increased growth, stress tolerance and disease resistance against Vibrio harveyi in Asian seabass (Lates calcarifer) juvenile

An 8-week husbandry trial was carried out toexamine the impacts of graded levels of dietary fulvic acid (FA) on growth, stress, and disease resistance of Asian seabass (Lates calcarifer, 38.2 g) juveniles. Five levels of FA were included in a basal diet (470 g kg-1 crude protein, 150 g kg-1 crude lipid) to prepare experimental diets, including: 0 (control), 2.5, 5.0, 10, and 15 g kg-1 diet. Two hundred and twenty-five fish (38.2 ± 0.1 g) were stocked randomly into 15 1000-L circular polyethylene tanks (15 fish tank-1) filled with 800 L disinfected seawater and fed with the experimental feeds three times daily. Each dietary treatment had three replicates. Tanks were supplied with seawater (32.2 °C, 45.0 ppt) in a flow-throw system. At the end of the husbandry trial, fish were challenged with Vibrio harveyi and air exposure stress for one min. Fish fed FA-supplemented diets showed a positive quadratic growth response, and those fed with a 5 g FA kg-1 diet had higher final weight and weight gain percentage than the control. Feed intake in fish fed FA-supplemented diets were higher than in control, showing significant linear and quadratic trends (P < 0.05). The highest and lowest skin mucus lysozyme (LYZ) and serum alternative complement pathway (ACH50) activities were in fish fed 10 and 15 g FA kg-1 diets, respectively, exhibiting a quadratic response to dietary FA. Serum total protein level (TP) in fish fed FA-supplemented diets was higher than in the control group. Medium or high levels (10–15 g kg-1) of FA significantly enhanced the survival rate against Vibrio harveyi, which was associated with increased activities of serum lysozyme and ACH50 as well as liver glutathione peroxidase activity in these groups. Air exposure induced oxidative stress in all treatments and gradually reduced antioxidant enzyme activities associated with increased malondialdehyde content in the liver. Furthermore, air exposure suppressed some immune responses, including serum total immunoglobulin and TP levels. Still, LYZ activity was restored after 24 h, with the highest level found in fish fed 5 g FA kg-1 diet. Based on the broken-line regression analysis, the adequate level of FA in the diet for Asian seabass is 4.4 g kg-1.

ROS-induced moderate autophagy of haemocytes confers resistance of Mercenaria mercenaria to air exposure stress

Air exposure (AE) is a significant environmental stressor that can lead to desiccation, hypoxia, starvation, and disruption of cellular homeostasis in marine bivalves. Autophagy is a highly conserved catabolic pathway that facilitates the degradation of damaged macromolecules and organelles, thereby supporting cellular stress responses. To date, autophagy-mediated resistance mechanisms to AE stress remain largely elusive in bivalves. In this study, we performed a multi-tool approach to investigate the autophagy-related physiological regulation in hard clams (Mercenaria mercenaria) under different duration of AE (T = 0, 1, 5, 10, 20, 30 days). We observed that autophagy of haemocytes was significantly activated on day 5. However, autophagy activity began to significantly decline from day 10 to day 30. Autophagy was significantly inhibited after antioxidant treatment, indicating that reactive oxygen species (ROS) was an endogenous inducer of autophagy. A significant decline in the survival rate of hard clams was observed after injection of ammonium chloride or carbamazepine during AE stress, suggesting that moderate autophagy was conducive for clam survival under AE stress. We also observed DNA breaks and high levels of apoptosis in haemocytes on day 10. Activation of apoptosis lagged behind autophagy, and the relationship between autophagy and apoptosis might shift from antagonism to synergy with the duration of stress. This study provides novel insights into the stress resistance mechanisms in marine bivalves.

Rapid synthesis of two photoluminescent pyridinium manganese-based halides by an anti-solvent method

The zero-dimensional Mn2+-based halides have efficient emission and good stability due to their unique crystal and electronic structures. Herein, a rapid anti-solvent method was used to prepare two lead-free manganese-based metal halides, (PP)3MnBr5 and (CP)2MnBr4, where PPB (1-phenacylpyridinium bromide) and CPB (cetylpyridinium bromide) were used as organic ion sources. Single crystal of (PP)3MnBr5 was grown and its structure was solved by XRD. In both compounds, (MnBr4)2- is isolated by organic molecules to form a 0-dimensional structures, exhibiting different fluorescent thermal stability and photoluminescence lifetimes. (PP)3MnBr5 shows a strong narrow emission band at 510 nm with a high photoluminescence quantum yield of 73 % and high environmental and thermal stability. (CP)2MnBr4 has a yellow-green emission band at 525 nm with a photoluminescence quantum yield of 28 %. (PP)3MnBr5 has a higher atmosphere and thermal stability than (CP)2MnBr4. After exposure in air for 1000 h, the luminescence intensity of (PP)3MnBr5 is 95 % of the initial value. At 423.15 K, the luminescence intensity of (PP)3MnBr5 is 79 % of the initial value.

Resistivity size effect in epitaxial VNi2 layers

Epitaxial VNi2 layers are deposited onto MgO(001) and their resistivity ρ measured as a function of layer thickness d = 10.5–138 nm to quantify the resistivity size effect. The layers exhibit resistivity minima at both stoichiometric V:Ni = 1:2 composition and 700 °C growth temperature, which is attributed to electron scattering at V–Ni antisite defects and is described using the ordering parameter within the framework by Rossiter. A cube-on-cube epitaxy of the fcc parent structure on MgO(001) leads to two possible layer orientations for orthorhombic VNi2(010) and VNi2(103), resulting in considerable atomic disorder at domain boundaries, consistent with relatively small x-ray coherence lengths of 8 and 14 nm in-plane and along the growth direction of a 33.5 nm thick layer. In situ ρ vs d measurements yield a bulk resistivity of ρo = 46 ± 2 μ Ω cm and a benchmark quantity of ρoλ = (138 ± 5) × 10−16 Ω m2, where λ is the bulk electron mean free path. Air exposure causes a minor resistivity increase due to 2 ± 1 nm thick surface oxide that perturbs the surface potential. Resistivities at 77 K are Δρ = 16 ± 3 μ Ω cm below those at room temperature. This Δρ is thickness independent and is close to the previously predicted 13.9 μ Ω cm bulk resistivity for VNi2 along [100]. However, the measured bulk resistivity is well above this prediction, which is attributed to electron scattering at domain boundaries/atomic disorder. Consequently, the theoretically predicted superior directional conduction cannot be experimentally confirmed in this study. The overall results indicate that VNi2 is only a promising compound for narrow interconnects if a synthesis scheme can be developed that results in a strong atomic order, a negligible domain boundary density, and a [100] crystalline orientation along the transport direction.

Influences of two transport strategies on AMPK-mediated metabolism and flesh quality of shrimp (Litopenaeus vannamei).

Water-free transportation (WFT), as a novel strategy for express delivery of live shrimp (Litopenaeus vannamei), was developed recently. However, air exposure during this transportation arouses a series of abiotic stress to the shrimp. In the present study, the influences of WFT stress on glycolysis and lipolysis metabolism and meat quality (umami flavor and drip loss) were investigated in comparison with conventional water transportation (WT). The results showed that type II muscle fibers with the feature of anaerobic metabolism were dominated in shrimp flesh. In addition, the increments of intracellular Ca2+ was detected in WFT and WT, which then activated the AMP-activated protein kinase pathway and promoted the consumption of glycogen, as well as the accumulation of lactate and lipolysis, under the enzymolysis of hexokinase, pyruvate kinase, lactate dehydrogenase and adipose triglyceride lipase. Glycogen glycolyzed to latate. Meanwhile, ATP degraded along with glycolysis resulting in the generation of ATP-related adenosine phosphates such as inosine monophosphate with umami flavor and phosphoric acid. More remarkable (P < 0.05) physiological changes (except lactate dehydrogenase and lactate) were observed in WFT compared to WT. Additionally, the fatty acid profile also slightly changed. The transport stress induced significant energy metabolism changes of shrimp flesh and therefore effected the flesh quality. The intensifications of freshness (K-value) of shrimp flesh were detected as a result of ATP degradation, which were more pronounced after WFT. However, the drip loss of shrimp flesh was more significantly increased (P < 0.05) after WFT compared to WT. © 2023 Society of Chemical Industry.

Effect of temperature, air exposure and gas mixture on Pd82–Ag15–Y3 membrane for hydrogen separation

Material characterization, hydrogen permeation, and separation properties of a novel ternary Pd82Ag15Y3 membrane were evaluated by feeding single gases and several mixtures at temperature and pressure ranges of 300–600 °C and 1.0–3.0 bar (abs), respectively. The Pd82–Ag15–Y3 membrane was prepared by cold rolling and was characterized by ∼38 μm of thickness. When exposed to air at different temperature and constant pressure of 1 bar, the membrane showed good thermal and chemical stability. In particular, its surface area increased from 615 μm2 at 25 °C to 685 μm2 at 500 °C indicating a potential improvement of hydrogen permeation. However, several agglomerates consisting of metal oxides were formed on the surface at the highest temperature. The temperature was -then- kept constant at 400 °C and the pressure was varied to analyze the effects of singles gases and several mixtures on the hydrogen permeation characteristics. When exposed to pure gases, such as H2 and N2, the membrane showed an H2 permeability of 9.1 × 10−11 mol m−1 s−1.Pa−0.9 and “n” value of 0.9 due to the presence of Y, while no N2 was detected in the permeate stream, respectively. So, the membrane was considered to be completely selective towards H2 permeation. When mixtures were used, the hydrogen permeation decreased by its original value due to the presence of other gases, such as N2, CH4, CO2 and CO. The presence of CO particularly affected the H2 permeating flux due to the competitive adsorption of both gases on the Pd-alloy surface. Finally, the Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Atomic Force Microscope (AFM) and X-ray diffraction (XRD) analysis were performed to observe any changes in the surface and structure of pristine and used membrane.

Achieving superior moisture-resistant and electrochemical properties of chlorine-rich Li-argyrodites via high oxygen dose

Cl-rich Li-argyrodites are promising solid electrolytes (SEs) used in all-solid-state Li batteries (ASSLBs) owing to the fast ion transport. However, they are unstable in the air and their compatibility to metallic Li still needs to be strengthened. Here, we improve these properties through O doping with a relatively high concentration. The high O solid solution in the argyrodite lattice is verified. The optimized Li5.7PS4.5O0.2Cl1.3 SE possesses an enhanced room temperature ionic conductivity. In parallel, in the sample with a relatively high oxygen dose, a Cl-O coexistence interface layer is revealed at the Li|SE interface region, associated with the formation of LiCl and Li3OCl interphases. The highest amount of Li3OCl appears also in the interface of Li5.7PS4.5O0.2Cl1.3 SE. Along with a more stable PS4-xOx unit, a proper O doing concentration is beneficial to mitigate the decomposition rate of SEs and to improve the compatibility of SE against Li metal. Moreover, Li5.7PS4.5O0.2Cl1.3 gains significantly enhanced air stability in contrast to the O-free sample. Consequently, the ASSLBs using both pristine and air-exposed Li5.7PS4.5O0.2Cl1.3 SE demonstrate decent electrochemical performance. In sharp contrast, the ASSLBs using the O-free argyrodite SE after air exposure cannot work for even one cycle. A high amount of O incorporation in Cl-rich Li-argyrodite SEs is thus a facile and effective route for achieving good overall performance including a high ionic conductivity, Li|SE interface stability, Li dendrite suppression capability, and notably, air stability.

Gestational ozone inhalation elicits maternal cardiac dysfunction and transcriptional changes to placental pericytes and endothelial cells.

Ozone (O3) is a criteria air pollutant with the most frequent incidence of exceeding air quality standards. Inhalation of O3 is known to cause lung inflammation and consequent systemic health effects, including endothelial dysfunction. Epidemiologic data have shown that gestational exposure to air pollutants correlates with complications of pregnancy, including low birth weight, intrauterine growth deficiency, preeclampsia, and premature birth. Mechanisms underlying how air pollution may facilitate or exacerbate gestational complications remain poorly defined. The current study sought to uncover how gestational O3 exposure impacted maternal cardiovascular function, as well as the development of the placenta. Pregnant mice were exposed to 1PPM O3 or a sham filtered air (FA) exposure for 4 h on gestational day (GD) 10.5, and evaluated for cardiac function via echocardiography on GD18.5. Echocardiography revealed a significant reduction in maternal stroke volume and ejection fraction in maternally exposed dams. To examine the impact of maternal O3 exposure on the maternal-fetal interface, placentae were analyzed by single-cell RNA sequencing analysis. Mid-gestational O3 exposure led to significant differential expression of 4021 transcripts compared with controls, and pericytes displayed the greatest transcriptional modulation. Pathway analysis identified extracellular matrix organization to be significantly altered after the exposure, with the greatest modifications in trophoblasts, pericytes, and endothelial cells. This study provides insights into potential molecular processes during pregnancy that may be altered due to the inhalation of environmental toxicants.

Lightweight and self‐healing thermally expandable microsphere/silver composites with segregated conductive network for high‐efficiency electromagnetic interference shielding

AbstractPolymer‐based electromagnetic interference (EMI) shielding materials with lightweight, self‐healing and high shielding performance show a wide application in electronics, medicine, national defense, aerospace and other fields. However, the conflict between a good conductive network structure and obtaining low density and excellent self‐healing property brings about tremendous challenges for fabricating these polymer‐based materials. Herein, a lightweight and self‐healing thermally expandable microsphere / silver (TEM/Ag) EMI shielding composites were prepared through a thermal foaming process. Due to the segregated Ag conductive network and expanded porous microsphere structure, the TEM/Ag composites possessed low density (0.095 g/cm3) and super‐high EMI specific shielding effectiveness (2816.3 dB cm2/g). In addition, benefiting from this unique structure, the composites exhibited excellent EMI shielding durability that can withstand ultrasonic washing 6 h (100 W), ethanol (99.5% purity), strong acid (pH 2.0), strong base (pH 12.0), NaCl solution soaking and long‐term air exposure (180 days). Furthermore, the inherent long‐chain entanglement imparts the composites a self‐healing feature, and 86% of the EMI shielding effectiveness can be maintained after self‐healing procedure.

The Effect of Air Exposure on the Hydrogenation Properties of 2Mg-Fe Composite after Mechanical Alloying and Accumulative Roll Bonding (ARB)

In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and processed it via accumulative roll bonding (ARB) (MA+ARB). Our primary focus was to analyze the impact of ambient air exposure while also evaluating the processing route. Some powder samples were exposed to air for 12 months (stored in a glass desiccator with an average yearly temperature and relative humidity of ~27 °C and 50.5%) before undergoing ARB processing. The Mg samples obtained after ARB processing exhibited a (002)-type texture. Our results demonstrate that all samples, including those processed via ARB, could rapidly absorb hydrogen within a matter of minutes despite considerable differences in surface area between powders and rolled samples. Grain size reduction by MA and ARB processing and texturing may have influenced this behavior. ARB-processed samples reached approximately 60% (~1.8 wt.%) of their maximum acquired capacity within just 24 min compared to powders (~2.2 wt.%) stored for a year, which took 36 min. In addition, the desorption temperatures (~300 °C) were lower than those of MgH2 (~434 °C). The absorption and desorption kinetics remained fast, even after prolonged exposure to air. Although there were minor variations in capacities, our overall findings are promising since scalable techniques such as ARB have the potential to produce hydrogen storage materials that are both safe and cost-effective in a highly competitive market.

OS01-06: Development and characterization of Bronchus-on-a-Chip in a novel microfluidic platform suitable for air exposure

OS01-06: Development and characterization of Bronchus-on-a-Chip in a novel microfluidic platform suitable for air exposure

Meat Quality Changes in Aged Pork Loin using Jeju Volcanic Scoria Earthenware.

This study aimed to investigate changes in the quality of meat aged using Jeju scoria earthenware. Water-holding properties, pH, color, tenderization, fatty acid composition, and free amino acid characteristics of aged pork loin were evaluated to determine the effects of wet and dry (normal and Jeju Scoria) aging methods and aging time (0, 10, 20, 30, and 40 days) on meat quality. The aging methods altered pH and CIE L* after 10 days of aging. However, the aging method did not alter the pH and CIE L* of the aged pork loin after 10 days of aging. The shear force was significantly lower in the Scoria aging method than in the wet aging method after 10 and 20 days of aging. Both the normal and Scoria aging methods increased aging loss compared to the wet aging method, which could be attributed to longer air exposure times of the two non-packaged aging methods than in the packaged aging method. The scoria aging method had significantly higher contents and ratios of saturated (SFA) to mono-unsaturated fatty acids but lower ratios of poly-unsaturated fatty acids to SFA than the wet aging method. The content of most free amino acids significantly increased with aging time, especially those related to the sweet, and umami categories. In summary, this study suggests that the Scoria aging method provides positive aspects of eating quality, such as improvement of meat tenderness and taste, including umami, with minimum changes in the overall meat quality.

Robust Conveniently Sealable Container for High-Temperature Single-Crystal Growth Out of Reactive Melts with High Vapor Pressure

The high-temperature crystal growth of intermetallics often asks for sealing of the materials in a protective atmosphere. Here, we report on the development of a convenient sealing method for alkali-containing melts, with high vapor pressure and reactivity. Our newly designed container made of high-temperature resistant steel can be sealed manually and reliably without any air exposure of the containing material. The closed container may be heated in air up to at least 1150 °C. The containers were applied for the development and optimization of a high-temperature self-flux growth of KFe1−xAg1+yCh2 (Ch = Se, Te) single crystals. Their crystal structure and the low-temperature electrical resistance are presented. The successful growths of these air-sensitive materials out of a reactive self-flux confirm the reliability of the container.

Chemical Fate of Oils on Indoor Surfaces: Ozonolysis and Peroxidation.

Unsaturated triglycerides found in food and skin oils are reactive in ambient air. However, the chemical fate of such compounds has not been well characterized in genuine indoor environments. Here, we monitored the aging of oil coatings on glass surfaces over a range of environmental conditions, using mass spectrometry, nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) techniques. Upon room air exposure (up to 17 ppb ozone), the characteristic ozonolysis products, secondary ozonides, were observed on surfaces near the cooking area of a commercial kitchen, along with condensed-phase aldehydes. In an office setting, ozonolysis is also the dominant degradation pathway for oil films exposed to air. However, for indoor enclosed spaces such as drawers, the depleted air flow makes lipid autoxidation more favorable after an induction period of a few days. Forming hydroperoxides as the major primary products, this radical-mediated peroxidation behavior is accelerated by indoor direct sunlight, but the initiation step in dark settings is still unclear. These results are in accord with radical measurements, indicating that indoor photooxidation facilitates radical formation on surfaces. Overall, many intermediate and end products observed are reactive oxygen species (ROS) that may induce oxidative stress in human bodies. Given that these species can be widely found on both food and household surfaces, their toxicological properties are worth further attention.

Evaluating Fermentation Quality, Aerobic Stability, and Rumen-Degradation (In Situ) Characteristics of Various Protein-Based Total Mixed Rations.

The purpose of this experiment was to evaluate changes in fermentation quality, chemical composition, aerobic stability, anti-nutritional factors, and in situ disappearance characteristics of various protein-based total mixed rations. Soybean meal (control, non-fermented), fermented cottonseed meal (F-CSM), and fermented rapeseed meal (F-RSM) group were used to prepare the TMRs with corn, whole-plant corn silage, corn stalks, wheat bran, and premix. The test groups were inoculated at 50% moisture with Bacillus clausii and Saccharomyces cariocanus and stored aerobically for 60 h. The nylon-bag method was used to measure and study the rumen's nutrient degradation. The pH of all TMRs after 48 h of air exposure was below 4.8, whereas that of the F-CSM and control and F-RSM groups increased to 5.0 and >7.0, respectively. After 8 h of aerobic exposure, the temperatures of all groups significantly increased, and 56 h later, they were 2 °C higher than the surrounding air. The lactic acid concentration in the F-CSM and F-RSM groups increased after 12 h of aerobic exposure and then decreased. The acetic acid concentrations in the fermented groups decreased significantly with the increasing air-exposure time. The yeast population of the TMRs increased to more than 8.0 log10 CFU/g before 72 h of air exposure, followed by a decrease in the population (5.0 log10 CFU/g). After fermentation, the free gossypol (FG) concentration in F-CSM decreased by half and did not change significantly during the air-exposure period. Fermentation with probiotics also reduced the F-RSM's glucosinolate concentration, resulting in a more than 50% detoxification rate. Compared with the F-CSM and F-RSM groups, the effective degradation rates of nutrients in the control group were the lowest, and the dry matter (DM), crude protein (CP), natural detergent fiber (NDF), and acid detergent fiber (ADF) all degraded effectively at rates of 28.4%, 34.5%, 27.8%, and 22.8%, respectively. Fermentation with B. clausii and S. cariocanus could improve the fermentation quality and nutrient composition, decrease the anti-nutritional factor, and increase nutrient degradation of the TMR with cottonseed meal or rapeseed meal as the main protein source, thus achieving detoxification.

Surface Design Engineering of LiTaO3 Coating on Li-Excess Li2NiO2 Cathode Additive for Lithium-Ion Batteries

The latest research has mainly focused on enhancement in the energy density of lithium-ion batteries (LIBs) to satisfy the rigorous industrial demands. As the most common approach for improving the energy density of LIBs, the utilization of high capacity anode materials, such as silicon suboxide (SiOx), has been highlighted, instead of graphite. SiOx anodes are known to have a high specific capacity and low operating voltage (< 0.5 V vs. Li/Li+). However, the severe initial capacity loss induced by the formation of solid electrolyte interphase (SEI) limits their commercial use in LIBs. To compensate for the initial loss of available Li+, the application of Li-excess cathode additives has been considered as the most practical strategy for supplying surplus Li+ during the initial charge process. In this respect, Li2NiO2 is a suitable cathode additive because it offers a high initial charge capacity (≥ 320 mAh g-1) and a compatible operating voltage with commercial cathode materials. Surface protection of Li2NiO2 is still required, however, due to its vulnerability to moisture (H2O) and carbon dioxide (CO2) in the ambient atmosphere. Moreover, Li2NiO2 becomes more structurally unstable during cycle due to oxygen (O2) gas evolution, leading to the formation of microcracks. To overcome these obstacles, we suggest a functional LiTaO3 coating layer onto the surface of Li2NiO2 for structural stabilization. In practice, the LiTaO3 coating layer can effectively suppress the production of impurities (i.e., LiOH and Li2CO3) at the surface of Li2NiO2 after air exposure. Furthermore, the gas evolution and microcracks can be minimized by enhancing the structural stability of Li2NiO2 during cycling. These synergetic effects of the LiTaO3 coating layer can provide clear insights for the development of Li-excess cathode additives for achieving advanced LIBs.

The effects of acutely elevated ammonia concentrations on haemolymph parameters in the Mediterranean mussel, Mytilus galloprovincialis

In aquaculture systems, ammonia nitrogen is a major component of waste products arising from the metabolism of cultured organisms and can significantly affect the quality of the rearing environment. The purpose of the current study was to determine modulation of the haemocyte population and selected haemolymph biochemical parameters of the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1919) exposed to acutely elevated ammonia concentrations.In order to investigate the extent and dynamics of an expected reduction of physiological fitness and survival rate of cultured mussels the stress-on-stress test was conducted combining ammonia and air exposure. The latter test illustrated the extent of reduced mussel physiological fitness and survival rate upon 72 h exposure to 10 and 30 mM NH4Cl in experimental tanks followed by additional exposure to air. Mussels cultured for up to 48 h in experimental tanks comprising 5, 10 and 30 mM NH4Cl, revealed dose and time dependent increase in haemolymph enzyme lactate dehydrogenase levels, urea, and uric acid metabolite levels, as well as the corresponding redistribution in haemocyte population profiles, indicating an inherent response of this organism to ammonia. Finally, a significant negative linear correlation between the mussel hyalinocytes subpopulation and the mean urea levels was observed. The obtained result suggests a possible function of basophilic and acidophilic granulocyte subpopulations in ammonia metabolism leading to urea synthesis by means of surplus ammonium ions are sequestered and extracted from the body. Therefore, defined modulation of the mussel haemocyte population structure may serve as an accurate bioindicator of mussels exposure to acutely elevated ammonia concentrations in environmental and aquaculture biomonitoring studies.

Exposure to airborne polychlorinated biphenyls and type 2 diabetes in a Danish cohort

BackgroundPrevious research indicates an association between higher-chlorinated polychlorinated biphenyls (PCBs) and type 2 diabetes (T2D). However, less is known about the extent to which PCB exposure in indoor air, composed primarily of lower-chlorinated PCBs, affects T2D risk. We assessed the association between indoor air exposure to PCBs in residential buildings and T2D incidence. MethodsThe register-based ‘Health Effects of PCBs in Indoor Air’ (HESPAIR) cohort comprises 51,921 Danish residents of two residential areas with apartments built with and without PCB-containing materials (reference apartments). We assessed exposure status by combining register-based information on relocation history with extrapolated values of exposure based on PCB-measurements in indoor air from subsets of the apartments. T2D cases were identified in the Danish registers during 1977–2018. We estimated adjusted hazard ratios (HR) and 95% confidence intervals (CI) using Cox regression analyses with time-varying exposure. ResultsWe identified 2737 incident T2D cases during the follow-up. Exposure to ≥3300 ng/m3 PCB × year (3rd tertile of PCByear) was associated with higher risk of T2D (HR 1.15, 95% CI 1.02–1.30) compared with exposure to <300 ng/m3 PCB × year (reference). However, among individuals with lower cumulated PCByear, the risk was similar to residents with exposure <300 ng/m3 PCB × year (300–899 ng/m3 PCB × year: HR 0.98, 95% CI 0.87–1.11; 900–3299 ng/m3 PCB × year: HR 0.96, 95% CI 0.83–1.10). DiscussionWe observed a marginally higher risk of T2D, but there was no evidence of an exposure-response relationship. The results should be interpreted with caution until confirmed in other independent studies of PCB exposure in indoor air.

Native Silicon Oxide Properties Determined by Doping.

The physico-chemical properties of native oxide layers, spontaneously forming on crystalline Si wafers in air, can be strictly correlated to the dopant type and doping level. In particular, our investigations focused on oxide layers formed upon air exposure in a clean room after Si wafer production, with dopant concentration levels from ≈1013 to ≈1019 cm-3. In order to determine these correlations, we studied the surface, the oxide bulk, and its interface with Si. The surface was investigated using the contact angle, thermal desorption, and atomic force microscopy measurements which provided information on surface energy, cleanliness, and morphology, respectively. Thickness was measured with ellipsometry and chemical composition with X-ray photoemission spectroscopy. Electrostatic charges within the oxide layer and at the Si interface were studied with Kelvin probe microscopy. Some properties such as thickness, showed an abrupt change, while others, including silanol concentration and Si intermediate-oxidation states, presented maxima at a critical doping concentration of ≈2.1 × 1015 cm-3. Additionally, two electrostatic contributions were found to originate from silanols present on the surface and the net charge distributed within the oxide layer. Lastly, surface roughness was also found to depend upon dopant concentration, showing a minimum at the same critical dopant concentration. These findings were reproduced for oxide layers regrown in a clean room after chemical etching of the native ones.