Air Exposure Periods Research Articles

The novel estuarine bioremediation target Gracilaria transtasmanica has high tolerance to light limitation, air-exposure and a broad range of salinities

AbstractIn-situ macroalgal bioremediation could help prevent and reduce estuarine eutrophication. However, estuaries are dynamic ecosystems characterized by fluctuating abiotic conditions. Therefore, target macroalgal species for in-situ estuarine bioremediation must be able to maintain productivity under a range of challenging abiotic conditions. The aim of this study was to assess the tolerance of the novel bioremediation target Gracilaria transtasmanica to ambient and extreme levels of salinity, air-exposure, and light limitation that occur in estuarine environments. Three separate experiments were conducted to assess tolerance to each factor and photosynthetic functioning and growth were used to quantify the tolerance range of G. transtasmanica in each experiment. Specific Growth Rate (SGR) was significantly affected by salinity, air-exposure, and light limitation. Gracilaria transtasmanica was able to grow in salinities of 5 to 35 ppt, but growth rates decreased with decreasing salinity. Air-exposure periods of up to 9 h were tolerated, but growth rates decreased as air-exposure period increased. Gracilaria transtasmanica was able to maintain growth with a loss of up to 75% of ambient light and was also able to tolerate short periods (48 h) of continuous darkness. Photosynthetic function was unaffected by salinity, air-exposure, or light limitation. These results demonstrate the high tolerance of G. transtasmanica to light limitation, air-exposure and a broad range of salinities. Consequently, this species could be cultivated in a range of habitat types within estuaries. However, the optimal habitats for cultivation will be submerged subtidal channels and lower intertidal mudflats where the impacts of freshwater inflows and air-exposure are reduced.

Preparation and Characterization of Prickly Ash Peel Oleoresin Microcapsules and Flavor Retention Analysis.

Prickly ash peel oleoresin (PPO) is a highly concentrated oil of Prickly ash essential oil and has a stronger aroma. However, its low water solubility, high volatility, difficulty in transport and storage, and decomposition by light, heat, and oxygen limit its wider application. To solve this problem, this study used freeze-drying or spray-drying, with soybean protein isolate (SPI) or gum Arabic (GA), combined with aqueous maltodextrin (MD) as the encapsulating agents to prepare four types of PPO microcapsules (POMs). Spray-dried microcapsules with GA as the encapsulating agent achieved a high encapsulation efficiency (EE) of 92.31 ± 0.31%, improved the thermal stability of the PPO, and had spherical morphology. (Headspace solid-phase microextraction/gas chromatography-mass spectrometry) HS-SPME/GC-MS detected 41 volatile compounds in PPO; of these, linalool, β-myrcene, sabinene, and D-limonene were identified as key flavor components. Principal component analysis (PCA) effectively distinguished the significant differences in flavor between PPO, spray-dried SPI/MD microcapsules (SS), and spray-dried GA/MD microcapsules (SG). During 15 days of air-exposure, the loss of flavor from SG (54.62 ± 0.54%) was significantly lower than PPO (79.45 ± 1.45%) and SS (57.55 ± 0.36%). During the air-exposure period, SG consistently had the highest antioxidant capacity, making it desirable for PPO packaging, and expanding its potential applications within the food industry.

A facultative mutualism between habitat-forming species enhances the resistance of rocky shore communities to heat waves

Heat waves have increased in frequency, duration, and magnitude in recent decades, causing mass mortality events in terrestrial and aquatic ecosystems. Arguably, mass mortalities of habitat-forming organisms – i.e., dominant sessile organisms that define habitats via their own physical structure – would be amongst the most dramatic impact of heat waves because of their negative, cascading consequences on their associated biodiversity. However, the resistance of habitat-forming organisms to heat waves can be enhanced if they associate with secondary habitat formers able to tolerate and modulate extreme heat levels. Here we show that a seaweed of the Porphyra/Pyropia (P/P) clade can shield primary habitat-forming mussels, Brachidontes rodriguezii, from the impacts of extreme temperatures in a southwestern Atlantic rocky intertidal shore. By means of P/P removal experiments and surveys, we illustrate that P/P cover (a) buffers temperatures in the understory mussel beds during daytime air exposure periods in the summer, (b) reduces mussel mortality and leads to increased mussel body condition during warm summer periods, and (c) can prevent mass mortality of mussels during the course of a heat wave. Additionally, by means of a mussel removal experiment we illustrate that mussel cover is critical for P/P establishment, which is in consonance with the remarkably higher P/P densities and cover observed in mussel beds relative to exposed rock surfaces across a ~70 km coastal range. Collectively, these findings reveal a facultative mutualism where mussels provide a favorable substrate for P/P colonization and P/P attenuates heat mediated mortality on mussels. The ability of P/P to enhance the resistance of mussel beds to extreme heat events and the occurrence of similar P/P-mussel associations during spring-summer at globally dispersed sites suggests a widespread importance of P/P for the stability of mussel beds and their associated communities under warming climates.

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.

Development of Stable Layered Oxide Cathode Materials Assisted By Machine Learning for K-Ion Batteries

Recently, the emergence of an artificial intelligence method, especially a machine-learning (ML) approach, has shown its potential to accelerate research and development for materials science. On the other hand, density functional theory (DFT) calculations have the ability to predict materials properties with relatively high accuracy.1 In the field of battery researches, using traditional methods, such as the empirical trial and error methods, hinders the development of new advanced electrode materials, particularly in potassium-ion batteries (KIB).2-4 To address this issue, here we develop for the first time a protocol using a combined ML and DFT calculations for materials screening followed by experimental verification. Notably, layered oxide cathode materials, such as KxMnO2, which have been widely investigated for KIB due to their high energy and power densities, suffer from structural instability and highly hygroscopic nature. Therefore, this proposed protocol is used for designing structurally stable KxMnO2 with enhanced environmental stabilities and high electrochemical performances. Among the numbers of candidates, notably, the ML and DFT-assisted strategies identify P′3-type K0.3Mn0.9Cu0.1O2 (KMCO) as a promising cathode for a high-performance KIB application. Finally, the experimental results further prove that the KMCO cathode has substantially improved K-storage properties with high-power density and cycling stability even after 4-week air-exposure period. We believe that this study opens a new avenue for identifying and developing suitable electrode materials for future battery applications. References B. Scrosati, M. Bottini and T. Mustelin, Nanotechnol., 2007, 2, 598 —599.N. Yabuuchi, K. Kubota, M. Dahbi and S. Komaba, Chem. Rev., 2014, 114, 11636 —11682. A. Eftekhari, Z. Jian and X. Ji, ACS Appl. Mater. Interfaces, 2017, 9, 4404 —4419.N. Xiao, W. D. McCulloch and Y. Wu, J. Am. Chem. Soc., 2017, 139, 9475 —9478

Do re-ensiling time and application of Lactobacillus buchneri alter the characteristics of sugarcane silage?

AbstractThis study aimed to examine the effects of re-ensiling time and Lactobacillus buchneri on the fermentation profile, chemical composition and aerobic stability of sugarcane silages. The experiment was set up as a repeated measure design consisting of four air-exposure periods (EP)(0, 6, 12, and 24 h) microbial additive (A) (L. buchneri; or lack of there), with five replicates. Sugarcane was ground through a stationary forage chopper and ensiled in four plastic drums of 200-L capacity. After 210 days of storage, the drums were opened and half of the silage mass was treated with L. buchneri at the concentration of 105 cfu/g of forage. Subsequently, the silages were divided into stacks. The re-ensiling process was started immediately, at 0, 6, 12 and 24-hour intervals, by transferring the material to PVC mini-silos. Silos were opened after 120 days of re-ensiling. The use of L. buchneri reduced butyrate concentration but did not change ethanol or acetic acid concentrations and aerobic stability. An interaction effect between L. buchneri and re-ensiling time was observed for dry matter (DM) losses and composition. Lactobacillus buchneri is not effective in improving aerobic stability in re-ensiled sugarcane silages. However, less DM is lost in silages treated with L. buchneri and exposed to air for 24 h. Re-ensiling sugar cane in up to 24 h of exposure to air does not change final product quality.

Effects of Tidal Scenarios on the Methane Emission Dynamics in the Subtropical Tidal Marshes of the Min River Estuary in Southeast China.

In order to accurately estimate the effects of tidal scenarios on the CH4 emission from tidal wetlands, we examined the CH4 effluxes, dissolved CH4 concentrations, and environmental factors (including in situ pH, Eh and electrical conductivity, porewater SO42−, NO3−, and NH4+) during inundation and air-exposure periods in high- and low-tide seasons in the Min River Estuary in southeast China. By applying static and floating chambers, our results showed that the CH4 effluxes during the inundation periods were relatively constant and generally lower than those during the air-exposed periods in both seasons. When compared, the CH4 effluxes during the air-exposed periods were significantly higher in the high-tide season than those in the low-tide season. In contrast, CH4 effluxes during the inundation periods were significantly lower in the high-tide season than those in the low-tide season. During the inundation periods, dissolved CH4 concentrations were inversely proportional to in situ Eh. Under air-exposed conditions, CH4 effluxes were proportional to in situ pH in both seasons, while the dissolved CH4 concentrations were negatively correlated with the porewater SO42− concentrations in both seasons. Our results highlighted that CH4 effluxes were more dynamic between inundation and air-exposure periods compared to low- and high-tide seasons.

Surface oxidation of amorphous Si and Ge slanted columnar and mesoporous thin films: Evidence, scrutiny and limitations for infrared optics

Issues on the superficial oxidation of mesoporous amorphous silicon and germanium photonic layers generated at oblique angles are reported. Such films were designed to improve the transmittance of optical elements over the mid-IR window (3.6–4.9 μm) by removing the light reflection. These nanostructures were deposited on silicon substrates by e-beam evaporation at room temperature. IR ellipsometry and spectrophotometry studies combined with models based on effective medium approximations predicted the presence of silicon or germanium oxides. Such oxidation was evidenced by combining X-ray photoelectron spectroscopy and advanced (scanning-)transmission electron microscopy studies based on energy-dispersive X-rays and electron energy-loss spectroscopies. Both techniques also allowed to prove the formation of core-shell-type architectures consisting of pure Si or Ge surrounded by oxidized species, even for a Ge layer subsequently capped with a dense MgF2 coating. The different approaches used for preparing electron transparent specimens (tripod polishing and focused ion-beams) confirmed a fast oxidation of the Ge nanocolumns even for short air exposure periods, and allowed comparing it with the level of oxidation promoted from other pollutant sources. This work sheds light on the spontaneous undesired oxidation in Si or Ge slanted nanorods which can diminish the performances and limit further development of optical devices.

Tolerance assessment of the aquatic invasive snail Potamopyrgus antipodarum to different post-dispersive conditions: implications for its invasive success

The New Zealand mudsnail (NZMS) Potamopyrgusantipodarum (Gray, 1843) (Tateidae, Mollusca) is a successful invasive species able to alter the functioning of the invaded ecosystems. However, to arrive and establish in new aquatic ecosystems, this snail must survive to the overland translocation through aerial exposure and must tolerate the new physical and chemical conditions of the recipient ecosystem. In this study, we simulated different conditions for the NZMS invasion by combining two air exposure treatments (0 and 20 h) with different physical and chemical conditions of the rehydration water (low and normal water temperatures and normal and high water conductivities). Mortality, behavior and neonate production were compared across treatments. Air exposure caused a high percentage of mortality but survivors tolerated the subsequent abiotic conditions. Low temperatures and high conductivities altered the behavior of adult snails, increasing significantly their reaction time (i.e. time to start normal movement). This may have negative consequences for the survival of this species under natural conditions. Finally, these conditions did not affect significantly the production of neonates. These results supported that the surviving NZMS to a brief period of air exposure possess the ability to acclimate to contrasting abiotic conditions with a potential establishment of new populations and that survivors can reproduce in different abiotic conditions after an air exposure period.

Use of reflex indicators for measuring vitality and mortality of the snow crab (Chionoecetes opilio ) in captivity

The snow crab (Chionoecetes opilio) is one of the most important commercial crabs in the world; it is heavily exploited in Atlantic Canada, Alaska, the Sea of Japan and the Barents Sea. Catches in the Barents Sea north of Norway have increased dramatically in the last decade. Most of the world's catch is processed, frozen and exported overseas. However, recently there has been considerable interest in exporting live snow crab, particularly in Norway. The stress of capture and live transport can result in significant mortalities. In order to establish a live export industry for snow crab, the welfare of the animal must be monitored throughout all the steps of the live transport process. In this study the reactions of snow crabs exposed to increasing periods of air exposure were measured in terms of reflex indicators, incidence of mortality, blood lactate levels and blood protein and haemocyanin. Although this is not a specific live holding or live transport process the aim was to test the suitability of reflex indicators to reflect vitality (stress) and not just to predict mortality. This would be compared with traditional blood biochemistry techniques for measuring crustacean stress. The study demonstrated that the reflex index score (RIS) is suitable to assess the vitality of snow crab. Longer air exposure periods render higher mortality rates and less vital individuals. The authors believe using vitality reflex indicators would be a suitable way of measuring crab welfare during the live holding and transport process.

Reversibility of Graphene Photochlorination

The reversibility of graphene photochemical chlorination was investigated. A high content of Cl is obtained through photochlorination, without changing C hybridization. To accommodate the incorporated Cl, graphene corrugation takes place. However, due to weak bonding, Cl atoms desorb during air exposure and long periods of storage. Chlorination also leads to graphene doping. When Cl is removed, doping decreases and graphene returns to its original morphology. Only a small amount of Cl (Cl/C ∼ 0.1) remains strongly bonded to graphene, most likely at grain edges and defects. Therefore, to maintain a precise doping level, Cl trapping methods are essential. Moreover, Cl removal using laser irradiation can be used to tune doping in micrometric areas, making it a promising technique to be used in applications where different doping levels are needed.

Designing Air-Stable O3-Type Cathode Materials by Combined Structure Modulation for Na-Ion Batteries.

As promising high-capacity cathode materials for Na-ion batteries, O3-type Na-based metal oxides always suffer from their poor air stability originating from the spontaneous extraction of Na and oxidation of transition metals when exposed to air. Herein, a combined structure modulation is proposed to tackle concurrently the two handicaps via reducing Na layers spacing and simultaneously increasing valence state of transition metals. Guided by density functional theory calculations, we demonstrate such a modulation can be subtly realized through cosubstitution of one kind of heteroatom with comparable electronegativity and another one with substantially different Fermi level, by adjusting the structure of NaNi0.5Mn0.5O2 via Cu/Ti codoping. The as-obtained NaNi0.45Cu0.05Mn0.4Ti0.1O2 exhibits an increase of 20 times in stable air-exposure period and 9 times in capacity retention after 500 cycles, and even retains its structure and capacity after being soaked in water. Such a simple and effective structure modulation reveals a new avenue for high-performance O3-type cathodes and pushes the large-scale industrialization of Na-ion batteries a decisive step forward.

Intertidal seagrass models: Insights towards the development and implementation of a desiccation module

One of the main limitations found in the numerical models available to simulate seagrass dynamics is the absence of processes that differentiate intertidal from subtidal seagrass meadows, namely the desiccation undergone by the leaves when emerged. The main objective of this work is therefore to contribute towards the mechanistic development and testing of a desiccation module to be later coupled with a numerical seagrass model, discussing its limitations and potential further improvements.The formulations proposed were established from both literature revision and data analysis from a field experiment performed in intertidal meadows of Zostera noltei in Ria de Aveiro lagoon (NW Portugal). The Relative Water Content (RWC), defined as a dynamic variable, depended on hydration and desiccation of seagrass leaves when exposed to air. The results showed that the module responded well to distinct tidal conditions (spring vs neap tides), different air temperature scenarios and sediment type based on grain size. Higher losses on RWC of seagrass leaves occur at spring tides, with higher air temperatures (over 38°C), longer air-exposure periods, colonizing medium sized sand sediments.This work provides new tools for further improvements in the simulation of intertidal seagrass dynamics when subjected intermittently to air exposure periods and abnormally high air temperatures, contributing to advances of the already existent models in a context of global changing environment.

Thriving of Zostera noltei under intertidal conditions: implications for the modelling of seagrass populations

The distribution of Zostera noltii seagrass in Ria de Aveiro lagoon (NW Portugal) is presently characterised by intertidal monospecific meadows. Numerical modelling approaches are useful supportive tools for environmental management, although the available numerical models for seagrasses generally overlook the intertidal processes, such as the water loss during air exposure periods. To achieve a better comprehension of seagrass dynamics and contribute to the development of more realistic models, this work aims to quantify the relative water content (RWC) of intertidal seagrass Z. noltii (RWCseagrass) in the aforementioned mesotidal lagoon. Experimental design included the sampling of Z. noltii shoots on ebbing and flooding tides, along two transects with different sediment types (medium sand vs. fine sand) and distinct intertidal heights (high, medium and lower intertidal), to assess the RWC during a tidal cycle under extreme spring tide conditions. Sediment descriptors such as the relative water content (RWCsediment), organic matter and grain size were also determined. The results showed no regular pattern between RWCseagrass variation and the different intertidal heights. Nevertheless, the seagrasses colonising the medium-sized sand sediments showed a higher RWCseagrass lost (about 20–31 %), when comparing with the samples from the finer sediments (8–16 %). Thus, these results suggest that the relative importance of sediment grain size is more effective in conditioning the RWCseagrass over a tidal cycle than the intertidal height itself (i.e. than different exposure times). This work highlights the importance of considering sediment type in the development of tools for seagrass recovery.

Effect of Air Exposure and Resubmersion on the Behavior and Oxidative Stress of Pacific White Shrimp Litopenaeus vannamei

AbstractThe effect of air exposure on antioxidant activities in Pacific white shrimp Litopenaeus vannamei was studied. The behavioral changes in the shrimp and the levels of superoxide dismutase (SOD), malondialdehyde (MDA), and total antioxidant competence (T‐AOC) in the muscles and hepatopancreas were determined after the shrimp were exposed to air and then resubmersed in water. Results showed that the duration of air exposure significantly influenced shrimp survival. The maximum air exposure period during which the shrimp could remain alive was 30 min. After 10 min of air exposure, the shrimp could survive when they were resubmersed in water. The T‐AOC in the hepatopancreas and muscles was significantly decreased in shrimp that were exposed to air for 20 min. The MDA content in the hepatopancreas was significantly higher for the 20‐, 30‐, and 40‐min air exposure groups than for the control group. During the resubmersion period, the MDA content in the shrimp hepatopancreas and muscles increased. For shrimp that were exposed to air for 10 min, SOD activities in the hepatopancreas and muscles were restored after 3 h of resubmersion in water. Our results indicate that air exposure can cause oxidative damage to Pacific white shrimp, but the damage can be reversed after the shrimp are resubmersed.

Influence of an Artificial Ageing on the Corrosion Behavior of AA2024

The aluminum alloys of the 2xxx series, such as the 2024 alloy, are widely used in the aircraft industry for the skin and wings of the aircrafts. However, the 2024 alloy can be affected by localized corrosion such as pitting corrosion, intergranular corrosion, exfoliation and stress corrosion cracking in chloride-containing environments (1-2). Most of the works performed concerning the corrosion behavior of the 2024 alloy correspond to continuous immersion tests. However, in service-life, airplane structures can be subjected to complex thermal and environmental cycling with exposure to an aqueous environment at room temperature, e.g. on the tarmac, followed by exposure to very low temperatures without aqueous environment, e.g. during the flight. In a previous work, the influence of cyclic exposure to chloride solutions on corrosion damage morphology developed on the 2024 alloy was studied (3). The results showed significant differences in corrosion morphology between continuous immersion tests and cyclic corrosion tests with cyclic corrosion tests leading to enhanced corrosion damage compared to continuous immersion tests. Furthermore, in service-life, airplane structures can be exposed to heat fluxes depending on their location on the airplane; this might lead to microstructural ageing of the material and consequently to an evolution of its corrosion behavior. The present work focuses on the influence of ageing on the corrosion behavior of the 2024 alloy.The corrosion behavior of the 2024 aluminum alloy was studied in a 1M NaCl for samples in the as received T351 metallurgical state and also for samples aged at 150°C for duration time between 0 h and 177 h. Open circuit potential measurements (OCP) showed a strong effect of the ageing treatment on the corrosion behavior of the 2024 alloy with OCP values decreasing when the ageing time increased. An ageing time of 55h was identified as a critical value on the OCP vs ageing time curve. This critical ageing time was also identified on the curves showing the mechanical properties (elongation to rupture, maximal strength) vs ageing time and correlated to a significant evolution of the microstructure by transmission electron microscopy. All the samples, i.e. T351 and aged samples, were submitted to both continuous immersion tests (CI tests) and cyclic corrosion tests (CF tests). A CF test consisted of three cycles of 24 hrs; each cycle was composed of an 8-hr immersion in the electrolyte followed by a 16 hrs air exposure period at -20°C. CI tests, called CI 24 h and CI 72 h, for duration of 24 h and 72 h respectively, were carried out as reference tests. Observations of the samples after the corrosion tests showed that, after CI tests, there was a transition of the corrosion morphology from intergranular to quite transgranular when the ageing time increased: for ageing time longer than 55h, transgranular corrosion was predominant. For all the samples, the corrosion defects morphology was strongly affected by the exposure conditions with CF tests promoting the intergranular corrosion and the branching of the intergranular corrosion defects.1. C. Augustin, E. Andrieu, C. Blanc, G. Mankowski, and J. Delfosse, J. Electrochem.Soc., 154, C637 (2007).2. W. Zhang and G. S. Frankel, J. Electrochem. Soc., 149, B510 (2002).3. C. Larignon, J. Alexis, E. Andrieu, C. Blanc, G. Odemer and J.-C. Salabura. J. Electrochem. Soc., 158, 1 (2011).

Corrosion Damages Induced by Cyclic Exposure of 2024 Aluminum Alloy in Chloride-Containing Environments

This paper focuses on the influence of cyclic exposure to chloride solutions on corrosion damage morphology developed on AA2024. The influence of the temperature during the air exposure periods was studied. Cyclic corrosion tests led to enhanced global corrosion damage compared to continuous immersion tests with residual mechanical properties of corroded samples significantly lower for cyclic tests. The corrosion morphology depended on the exposure conditions. For cyclic tests with air exposure periods at room temperature (CR tests), the corrosion defects were significantly longer; for a cyclic test with air exposure periods at −20 °C (CF tests), the propagation of corrosion defects was not promoted; however, the density of corroded grain boundaries was markedly increased. For CR samples, the corrosion damage observed was mainly explained taking into account electrochemical processes occurring at the tip of the defect which could be considered as an occluded zone characterized by a chloride-enriched electrolyte and H+ reduction as major cathodic reaction. For CF tests, the interaction between the stresses induced by the phase transformation of the medium i.e solidification and the hydrogen enrichment of the substrate could be a possible mechanism explaining the evolution of the global mechanical properties of the corroded samples.

Relationship between surface structure and separation performance of poly(ether sulfone) ultra-filtration membranes blended with surface modifying macromolecules

The poly(ether sulfone) (PES) membranes were prepared by blending of two types of surface modifying macromolecules (SMMs)-charged (cSMM) and fluorinated (fSMM). Also, membranes were fabricated in three different conditions: (1) at room temperature (RT) without air-exposure period (the period between film casting and immersion into coagulation bath), (2) at RT with 3 min air-exposure period and (3) at 90 °C with 3 min air-exposure period. The performances and physico-chemical characteristics of the membranes were evaluated. Membrane surface became more hydrophilic when cSMM was blended while more hydrophobic when fSMM was blended. Detailed analysis of the surface free energy demonstrated that the hydrophilic surface was resulted form strong Lewis base (solid)–acid (liquid) interaction while hydrophobic surface was resulted from the weak Lifshitz–van der Waals interaction. Atomic force microscopy (AFM) results could be interpreted by considering the orientation of nodule aggregates at the membrane surface under the casting bar and its relaxation during the air-exposure period between the film casting and immersion to the gelation bath. The pore size of the membranes measured by AFM was much larger than the pore size obtained by filtration experiment.

Air-Exposure Technique for the Formation of Artificial Lipid Bilayers in Microsystems

To develop a reliable method for on-chip bilayer lipid membrane (BLM) formation, which could be employed for use in a biosensor array platform, a polymer microfluidic device has been constructed, and the formation of suspended BLMs within it has been investigated. A simple, yet reproducible BLM formation protocol has been developed, in which a brief air-exposure period is employed to induce the rapid thinning of an initially thick lipid-solvent layer. The technique is rapid, reproducible, and amenable to the simple injection of proteins or analytes, as well as to buffer exchange on both sides of the membrane. Scaling up the technique for use in an array platform is also straightforward, the simultaneous formation of three individually addressable BLMs being demonstrated.

Alterações bromatológicas nas silagens de milho submetidas a crescentes tempos de exposição ao ar após "desensilagem"

O experimento foi conduzido em delineamento completamente casualizado, com o objetivo de avaliar os efeitos da exposição de uma silagem ao ar por zero, 12, 24 e 36 horas após a "desensilagem". A ensilagem de um cultivo de milho "safrinha" foi realizada no dia 18/05/2004 em mini-silos com capacidade de 30 litros, com quatro repetições por tratamento, quando os grãos de milho se encontravam no estádio ½ leitoso ½ farináceo. Os diferentes tempos de exposição ao ar após a "desensilagem" afetaram significativamente (P<0,05) o teor de fibra em detergente neutro, corrigido para cinzas e proteínas, e o teor de lignina em ácido sulfúrico. Não houve efeito nos carboidratos não estruturais e nas frações nitrogenadas. Conclui-se que um período de 12 horas de aerobiose, após a "desensilagem", afeta o valor nutritivo das silagens de milho.