Aeration Levels Research Articles

Quantification of oxidative stress in Saccharomyces pastorianus propagation: Gene expression analysis using quantitative reverse transcription polymerase chain reaction and flow cytometry

When confronted with environmental stress, yeast cell reacts, among others, by modifying the expression of specific genes. In this study, gene expression was analyzed via RT-qPCR to quantify the oxidative stress of Saccharomyces pastorianus during yeast propagation as a reaction to different aeration levels. Target genes were identified, and a reference gene system was developed. Fermentation experiments were conducted in shaking flasks, applying different shaking speeds to generate various aeration efficiencies. The cells were sampled at different propagation stages and, additionally to the expression study, analyzed by flow cytometry after staining with dihydroethidium (DHE) to quantify reactive oxygen species (ROS) inside the cells. The results indicate that high oxygen fermentation conditions led to an increased expression of the catalase-A gene CTA1 during propagation. Furthermore, the determination of cell internal ROS shows increasing oxidative stress over the process in accordance with the RT-qPCR measurements.

Measurement for bubble size distribution in bubbly oil with digital imaging technology

The high viscosity of lubricating oil limits the working speed of sliding bearing, and the viscosity of bubbly oil is less than that of lubricating oil at high shear rate. The viscosity of bubbly oil is related to bubble size distribution. An experimental device for generating microbubbles in bubbly oil is designed, and a method for measuring bubble size distribution in bubbly oil with different aeration levels is proposed based on digital imaging technology. The experimental results show that the size distribution of bubbles accords with lognormal distribution basically, and the higher the air volume fraction is, the larger the average diameter of bubbles is.

Static characteristics of high-speed bubble-oil-lubricated spiral groove thrust bearing

In this paper, the effect of bubble oil on the performance of spiral groove thrust bearing is Investigated. A theoretical model for thrust bearing is established based on bubble-oil two-phase flow considering centrifugal effect and viscosity-temperature relationship. The static characteristics of thrust bearing are analyzed. The result shows that both of viscosity-temperature effect and centrifugal effect can reduce the load capacity and friction torque. Meanwhile, with the increase of aeration level in bubble oil, the capacity, friction torque and maximum temperature rise of spiral groove thrust bearing are lower.

Effects of Different Aeration Treatments on Bacterial Diversity, Metabolic Activity, and Function in Constructed Wetlands

Bacteria play a key role in the removal of pollutants and nutrients in constructed wetlands. DNA and RNA high-throughput sequencing was used to investigate the diversity, metabolic activity, and function of bacteria in aquaculture wastewater and in constructed wetlands treated by different aeration levels. The results revealed that:① a total of 4042 operational taxonomic units (OTUs) were detected in aquaculture wastewater and constructed wetland treatment groups. α-Proteobacteria, γ-Proteobacteria, and Bacteroidia were the most diverse groups, and the constructed wetlands aeration treatment increased the bacterial diversity to a variable extent; ② α-Proteobacteria, γ-Proteobacteria, Bacteroidia, and Actinobacteria were the dominant groups both in the DNA and RNA sequencing results, and the metabolic activities of these four groups were significantly affected by the concentration of total nitrogen (TN) and nitrate nitrogen (NO3--N) in our study. ③ According to the FAPROTAX database, 56 bacterial functional groups were detected in our study, mainly including:chemoheterotrophy, aerobic chemoheterotrophy, fermentation, intracellular parasites, dark hydrogen oxidation, phototrophy, photoheterotrophy, and nitrate reduction. Functions related to the nitrogen cycle were observed in the results of function annotation, suggesting the important role of bacterial communities in the removal of nitrogen nutrients in constructed wetlands. These results will improve the understanding of bacterial community structures and functions during nutrient removal in aerated constructed wetlands.

Competitive Biosynthesis of Bacterial Alginate Using Azotobacter vinelandii 12 for Tissue Engineering Applications.

This study investigated the effect of various cultivation conditions (sucrose/phosphate concentrations, aeration level) on alginate biosynthesis using the bacterial producing strain Azotobacter vinelandii 12 by the full factorial design (FFD) method and physicochemical properties (e.g., rheological properties) of the produced bacterial alginate. We demonstrated experimentally the applicability of bacterial alginate for tissue engineering (the cytotoxicity testing using mesenchymal stem cells (MSCs)). The isolated synthesis of high molecular weight (Mw) capsular alginate with a high level of acetylation (25%) was achieved by FFD method under a low sucrose concentration, an increased phosphate concentration, and a high aeration level. Testing the viscoelastic properties and cytotoxicity showed that bacterial alginate with a maximal Mw (574 kDa) formed the densest hydrogels (which demonstrated relatively low cytotoxicity for MSCs in contrast to bacterial alginate with low Mw). The obtained data have shown promising prospects in controlled biosynthesis of bacterial alginate with different physicochemical characteristics for various biomedical applications including tissue engineering.

Aeration level in HDPE-lined nursery ponds that optimizes yield and production cost of preadult redclaw crayfish, Cherax quadricarinatus

The potential for commercial Australian redclaw crayfish culture is considered very significant. However, information on the effect that different water exchange and aeration levels has on growth, survival, yield and nursery production costs of redclaw is limited. We evaluated the effect of aeration levels in the yield and production cost of preadult redclaw crayfish, Cherax quadricarinatus, during the nursery phase. In a preliminary trial, 4 levels of water exchange: 0%, 2.5%, 5% and 7.5% day−1, were tested in 1.7 m diameter (2.26 m2) tanks, stocking 3.0 ± 0.2 g juveniles at a density of 15 juveniles m−2. After 60 days, the physicochemical water quality parameters were within the recommended intervals for cultivation of the species. Final weight, survival, biomass and FCR’s of pre-adult C. quadricarinatus did not show any significant differences (p > 0.05) among treatments so we conclude that adequate production of C. quadricarinatus during zero-water exchange nursing is feasible. With the previous information, 4 aeration levels (0, 6, 12 and 24 hr day−1) were evaluated in triplicate 100 m2 HDPE-lined outdoor ponds. Juveniles (3.5 ± 0.5 g) were stocked at a density of 15 juveniles’ m−2. After 84 days of cultivation, survival was not significantly different among treatments and varied within 86–87%. The highest final average weight, growth rate and biomass were obtained with 12 h of aeration per day (3.2 ton ha−1), but there were no significant differences from those obtained in ponds with continuous aeration (24 hr day−1). The feed conversion rates were within 0.72 − 0.75. We conclude that it is possible to maximize C. quadricarinatus production in HDPE-lined ponds without water exchange, maintaining aeration at a rate of at least 12 hr day−1. A cost analysis shows that, with this strategy, it is possible to reduce the electricity costs required for water pumping and aeration in 70% and 50%, respectively. With this, a reduction of 11.17% in the production cost of pre-adult C. quadricarinatus during the nursery phase is achieved, compared with the best published reports.

Evaluating acute toxicity in enriched nitrifying cultures: Lessons learned

Toxicological batch assays are essential to assess a compound's acute effect on microorganisms. This methodology is frequently employed to evaluate the effect of contaminants in sensitive microbial communities from wastewater treatment plants (WWTPs), such as autotrophic nitrifying populations. However, despite nitrifying batch assays being commonly mentioned in the literature, their experimental design criteria are rarely reported or overlooked. Here, we found that slight deviations in culture preparations and conditions impacted bacterial community performance and could skew assay results.From pre-experimental trials and experience, we determined how mishandling and treatment of cultures could affect nitrification activity. While media and biomass preparations are needed to establish baseline conditions (e.g., biomass washing), we found extensive centrifugation selectively destabilised nitrification activities. Further, it is paramount that the air supply is adjusted to minimise nitrite build-up in the culture and maintain suitable aeration levels without sparging ammonia. DMSO and acetone up to 0.03% (v/v) were suitable organic solvents with minimal impact on nitrification activity. In the nitrification assays with allylthiourea (ATU), dilute cultures exhibited more significant inhibition than concentrated cultures. So there were biomass-related effects; however, these differences minimally impacted the EC50 values. Using different nutrient-media compositions had a minimal effect; however, switching mineral media for the toxicity test from the original cultivation media is not recommended because it reduced the original biomass nitrification capacity.Our results demonstrated that these factors substantially impact the performance of the nitrifying inoculum used in acute bioassays, and consequently, affect the response of AOB-NOB populations during the toxicant exposure. These are not highlighted in operation standards, and unfortunately, they can have significant consequential impacts on the determinations of toxicological endpoints. Moreover, the practical procedures tested here could support other authors in developing testing methodologies, adding quality checks in the experimental framework with minimal waste of time and resources.

Effect of patient–ventilator asynchrony on lung and diaphragmatic injury in experimental acute respiratory distress syndrome in a porcine model

BackgroundPatient–ventilator asynchrony during mechanical ventilation may exacerbate lung and diaphragm injury in spontaneously breathing subjects. We investigated whether subject–ventilator asynchrony increases lung or diaphragmatic injury in a porcine model of acute respiratory distress syndrome (ARDS). MethodsARDS was induced in adult female pigs by lung lavage and injurious ventilation before mechanical ventilation by pressure assist–control for 12 h. Mechanically ventilated pigs were randomised to breathe spontaneously with or without induced subject–ventilator asynchrony or neuromuscular block (n=7 per group). Subject–ventilator asynchrony was produced by ineffective, auto-, or double-triggering of spontaneous breaths. The primary outcome was mean alveolar septal thickness (where thickening of the alveolar wall indicates worse lung injury). Secondary outcomes included distribution of ventilation (electrical impedance tomography), lung morphometric analysis, inflammatory biomarkers (gene expression), lung wet-to-dry weight ratio, and diaphragmatic muscle fibre thickness. ResultsSubject-ventilator asynchrony (median [interquartile range] 28.8% [10.4] asynchronous breaths of total breaths; n=7) did not increase mean alveolar septal thickness compared with synchronous spontaneous breathing (asynchronous breaths 1.0% [1.6] of total breaths; n=7). There was no difference in mean alveolar septal thickness throughout upper and lower lung lobes between pigs randomised to subject–ventilator asynchrony vs synchronous spontaneous breathing (87.3–92.2 μm after subject–ventilator asynchrony, compared with 84.1–95.0 μm in synchronised spontaneous breathing;). There were also no differences between groups in wet-to-dry weight ratio, diaphragmatic muscle fibre thickness, atelectasis, lung aeration, or mRNA expression levels for inflammatory cytokines pivotal in ARDS pathogenesis. ConclusionsSubject–ventilator asynchrony during spontaneous breathing did not exacerbate lung injury and dysfunction in experimental porcine ARDS.

Improving the environment for kelp hatchery culture in tanks with bottom aeration using a skeleton collector

Hydrodynamic and light conditions may be affected by the frame system that carries the string (collector) used to produce kelp seedling strings in kelp hatcheries. However, no studies have analysed the effect of the collector type on these key environmental factors to assess hatchery suitability. In this study, two experimental set-ups were designed to evaluate the hydrodynamic environment and light availability using two distinctive collectors that have been used for kelp hatchery cultures in tanks with bottom aeration. A standard collector of walled PVC pipe was compared with an alternative collector consisting of a steel skeleton with a fully open frame structure. The results show that the two types of collectors produced different environmental effects. The skeleton collector displayed a significantly lower reduction in the water velocity compared with the pipe collector, and therefore, its design favours water circulation and exchange through the system to a greater extent. This effect was more significant as the aeration level increased. The skeleton collector also provided better light availability, with a significance that depended on the illumination source positions at different faces of the collector. The differences were greater on the inside faces and with illumination from the sides of the collector. The findings are discussed based on prior experience and the literature on kelp hatchery practices.

Soil biological activity of short rotation crop at the maximum saturation with sunflower

Soil biological activity of short rotation crop at the maximum saturation with sunflower

Profiling Malt Enzymes Related to Impact on Malt Fermentability, Lautering and Beer Filtration Performance of 94 Commercially Produced Malt Batches

A largely defined series of hydrolytic enzymes active during malting and/or mashing, substantially determine the quality, profitability, and efficiency of the brewing process. These enzymes potentially hydrolyze starch, proteins and cell wall non-starch polysaccharides including β-glucan and arabinoxylan. Commercial malts (94) were assayed for the DP enzymes (limit dextrinase, beta/α-amylase), and NSP hydrolyzing enzymes (β-glucanase, xylanase, arabinofuranosidase, β-glucosidase). The levels of enzyme activity were related to conventional measures of malt quality such as extract, fermentability, protein, KI, DP, friability, wort viscosity, FAN, and β-glucan. These parameters were interrelated with less conventional measures of malt quality including coarse extract and fermentability (modified infusion mash 65 °C), lautering efficiency, the Small-scale Wort ‘I’ Filtration Test (SWIFT), and viscosity. Substantial variation was observed between the malt samples for all enzymes assayed. Australian barley, whether malted in Australia (n = 61) or China (n = 24), was observed to be of comparable quality. A limited set of Canadian barley samples (n = 9) were malted in China and produced malts with somewhat higher levels of extract, AAL, and some enzymes. Remarkably, the level of limit dextrinase was observed to be almost double that from previous investigations. Greater levels of steep water aeration were proposed to explain this dramatic increase. The interrelationships between the enzyme activities and malt quality identified, enable potential selection of novel malt quality parameters that are more predictive of a malt’s brewing performance (efficiency and quality) than current measures to provide a malt quality assessment system based on ‘functional’ malt quality.

Evaluation of PAO adaptability to oxygen concentration change: Development of stable EBPR under stepwise low-aeration adaptation

Recent research has shown the adaptability of Biological Nutrient Removal (BNR) systems to very low level dissolved oxygen (DO) concentration, mainly focusing in the nitrification ability that maintains the nitrogen oxidation process even at very low DO levels. Although step-wise aeration decrease on Enhanced Biological Phosphorus Removal (EBPR) is not fully comprehended. This study investigated the effect of reaching micro-aeration with adaptation strategies on EBPR performance. A step-wise oxygen concentration decrease, arriving at an average aeration level of 0.4 mgO2/L was evaluated, with an outcome of approximately 90 % phosphorus removal efficiency. Compared with different aeration modes, the highest phosphorus (P)-removal efficiency, P-release and lowest effluent phosphorus was achieved in gradual DO decrease strategy. On the other hand, an instant decrease in aeration from stable EBPR process from 2 mgO2/L to 0.4 mgO2/L adversely impacted P-removal by decreasing the efficiency to average 60 % and deteriorating the phosphorus removing microbial consortium. Comparison of results between instant and gradual DO-decrease, indicated the sensitivity of microorganisms to aeration. Microbial adaptation to decreased oxygen availability is crucial to reach high process performance. This study proposes, a potential aeration mode, which contributes in reduction of energy consumption in BNR systems through wastewater treatment.

Effect of crevice morphology on SRB activity and steel corrosion under marine foulers

Localized corrosion of submerged steel H-piles was detected in a Florida bridge spanning over a brackish river. Analysis of the water showed proliferation of sulfate reducing bacteria (SRB). The steel piles had coincident heavy marine growth that may support biofilms and biocorrosion. The objective of the research described here was to identify the role of the physical morphologies of macrofouling on SRB activity and the aggravation of microbiologically influences corrosion (MIC) of submerged steel bridge. Laboratory experiments were carried out in nutrient-rich environments inoculated with SRB, with both porous and laminate crevice conditions characteristic of soft and hard marine fouling. It was confirmed that SRB proliferation can occur within the crevice environments, but aeration levels under crevices with interaction with the bulk solution can affect SRB activity. Electrochemical impedance spectroscopy provided separation of environmental parameters and surface reaction parameters for the complicated systems relating to corrosion under the porous and laminate crevice geometries.

Enhancement of EAPR Treatment Using Double Aeration System and Uptake by Pakcoy (<i>Brassica rapa subsp. chinensis</i>)

This study was aimed at investigating the effect of electro-assisted and double aeration (EAPR-DA) system to enhance the lead removal in water and uptake by Pakcoy (Brassica rapa subsp. Chinensis). Variable regimes were created by 2 V of constant DC voltage using 2D stainless steel cathode-pot and Ti anode electrode, and aeration level of 10 L/min. The effectiveness of EAPR-DA, EAPR, phyto-aeration, and phytoremediation on the treatment was compared and evaluated by measuring the decrease of lead concentration in the water and accumulated in the plant using flame Atomic Absorption Spectroscopy. Plant stress was evaluated by phytomorphology changed and measurement chlorophyll content using UV-Vis Spectroscopy after the acetone extraction. The results showed that the EAPR-DA system using Pakcoy has a great ability to decrease the lead concentration in water compared with the EAPR, phyto-aeration, and phytoremediation. The removal ability in each reactor was 82.5%, 78.75%, 72.5%, and 61.875% respectively for EAPR-DA, EAPR, phytoremediation. and phyto-aeration. Excessive aeration in the root zone might inhibit lead adsorption by a plant in the phyto-aeration system. In general, the accumulation of lead in plant growth hydroponically has a large concentration in the roots compared to the shoot except for the EAPR-DA system which high adsorption of lead concentration in the shoot part. The BC (1.13) and TF (1.97) value of the EAPR-DA system was higher than the other systems, showing aeration can enhance high adsorption of lead in the root and then transported it into the shoots part. High chlorophyll total (54.89±14.31 mg/mL) and low chlorophyll a/b ratio (1.21±0.38) in the plant under the EAPR-DA system showed that the double aeration in the electro-assisted system encourages the high tolerance of the plant to the lead concentration.

Variation of branched tetraethers with soil depth in relation to non-temperature factors: Implications for paleoclimate reconstruction

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial membrane lipids that have been extensively used as tools for paleoclimate reconstruction. Temperature and pH were thought to be two major factors affecting the distributions of brGDGTs; however, the effects of other factors on the distribution of brGDGTs and related temperature and pH proxies in soil environments remain unclear. Here, we investigated iso- and br-GDGT distributions in three soil profiles (SPs) developed on bedrocks consisting of hornfels (HP), granite (GP), and basalt (BP), respectively. The downward environmental factors in these SPs differ, thus providing a chance to evaluate their effects on the distribution of brGDGTs. In the three SPs, the methylation degree for 5-methyl and total brGDGTs (MBT′5ME and MBT′), respectively, varied significantly downwards despite minor changes in soil temperature, highlighting a non-temperature effect. The depth-dependence of these proxies appears to be caused by the oxygen level. The MBT′ for 5- or 6-methyl brGDGTs (MBT′5ME and MBT′6ME), or total brGDGTs (MBT′), increased as the oxygen level decreased, suggesting tetramethylated brGDGTs (Ia, Ib, and Ic) would increase in abundance with decreased oxygen level. The two pH proxies, CBT and IR6ME, both decreased at lower oxygen levels. Such regulation of brGDGT compositions in response to oxygen availability could be explained by the changing bacterial communities that have different oxygen preferences. The possible oxygen level impact on the distribution of GDGTs could result in brGDGT-inferred temperature skewed towards higher values and pH towards lower values with decreased oxygen level. This finding may also have implications for the mechanism of soil aridity impact on the brGDGT-based proxies in semi-arid and arid regions, which is of profound importance for paleotemperature and hydroclimate reconstruction in loess-paleosol sequences. Increasing soil aridity could lead to changes in brGDGT-based proxies similar to that observed at the higher oxygen level, i.e., lower MBT′, higher CBT, and higher IR6ME. As soil aridity is generally associated with better aeration and higher oxygen level, we argue that changes in oxygen level might be the real cause of the bias in brGDGT-based proxies in soils from semi-arid and arid regions.

Erosion-corrosion behaviour of steels used in slurry pipelines

The regular replacement and maintenance of steel pipes used to transport the slurry processed in oil sands mining and extraction represent a major expense for oil sands operations. Erosion-corrosion tests reveal that the performance of the steels is strongly influenced by the slurry velocity, which affects the severity of the erosion-corrosion synergy. In this study, the erosion-corrosion behavior of API 5L X65, X70, and X80 steels was assessed at two different slurry velocities (3.5 and 5 m/s) and two different aeration levels or dissolved oxygen (DO) levels (0.6 and 3.8 ppm). Results of the tests were compared to those of an ASTM A1053 Gr.50 dual-phase (DP) stainless steel and AR400 hard plate. The tests were performed at 60 °C in sand-containing slurry (20% vol. silica) with 500 ppm chloride, which replicated common field conditions. Characterization of the steels was carried out with optical and scanning electron microscopy, energy dispersive x-ray spectrometry, x-ray diffraction technique, micro-mechanical probe, and electrochemical testing. The results showed that at the DO level of 3.8 ppm, the DP stainless steel featured the highest erosion-corrosion resistance at the slurry velocity of 3.5 m/s, while its performance was inferior to that of the carbon steels as the slurry velocity was increased to 5.5 m/s. At the lower DO level, the DP stainless steel erosion resistance was relatively similar to the carbon steels but deteriorated as slurry velocity was increased. Possible mechanisms responsible for the observed variations in the erosion-corrosion resistance under the testing conditions are analyzed and discussed.

Production of Lignocellulolytic Enzymes and Biomass of Trametes versicolor from Agro-Industrial Residues in a Novel Fixed-Bed Bioreactor with Natural Convection and Forced Aeration at Pilot Scale

Solid-state fermentation requires the development of more efficient cultivation systems for its industrial application. The objective of this work was to evaluate the effect of aeration regime on the production of biomass and several lignocellulolytic enzymes (laccase, manganese peroxidase, endoxylanase, β-glucosidase, and total cellulases) by Trametes versicolor in a novel fixed-bed solid-state pilot-scale bioreactor. Three regimes were assessed: natural convection, low aeration level (10 min every 6 h at 10 L/h air flowrate), and high aeration level (1 h every 6 h at 10 L/h air flowrate). The mushroom was grown on a medium based on lignocellulosic residues. The design of the bioreactor, as well as the control of aeration, humidity, and temperature of the beds, allowed T. versicolor to grow properly on the medium, reaching a maximum biomass production of 204.7 mg/g dry solid (ds). The influence that aeration regime had on the production of lignocellulolytic enzymes was determined. Low level of forced aeration favored obtaining the highest titers of laccase (6.37 U/g ds) compared to natural convection and high aeration level. The greatest lignin degradation was also verified for low aeration regime. For the first time, pilot scale cultivation of T. versicolor was reported in a fixed-bed bioreactor.

Fermentative Production of l-2-Hydroxyglutarate by Engineered Corynebacterium glutamicum via Pathway Extension of l-Lysine Biosynthesis

l-2-hydroxyglutarate (l-2HG) is a trifunctional building block and highly attractive for the chemical and pharmaceutical industries. The natural l-lysine biosynthesis pathway of the amino acid producer Corynebacterium glutamicum was extended for the fermentative production of l-2HG. Since l-2HG is not native to the metabolism of C. glutamicum metabolic engineering of a genome-streamlined l-lysine overproducing strain was required to enable the conversion of l-lysine to l-2HG in a six-step synthetic pathway. To this end, l-lysine decarboxylase was cascaded with two transamination reactions, two NAD(P)-dependent oxidation reactions and the terminal 2-oxoglutarate-dependent glutarate hydroxylase. Of three sources for glutarate hydroxylase the metalloenzyme CsiD from Pseudomonas putida supported l-2HG production to the highest titers. Genetic experiments suggested a role of succinate exporter SucE for export of l-2HG and improving expression of its gene by chromosomal exchange of its native promoter improved l-2HG production. The availability of Fe2+ as cofactor of CsiD was identified as a major bottleneck in the conversion of glutarate to l-2HG. As consequence of strain engineering and media adaptation product titers of 34 ± 0 mM were obtained in a microcultivation system. The glucose-based process was stable in 2 L bioreactor cultivations and a l-2HG titer of 3.5 g L−1 was obtained at the higher of two tested aeration levels. Production of l-2HG from a sidestream of the starch industry as renewable substrate was demonstrated. To the best of our knowledge, this study is the first description of fermentative production of l-2HG, a monomeric precursor used in electrochromic polyamides, to cross-link polyamides or to increase their biodegradability.

In-vivo lung fibrosis staging in a bleomycin-mouse model: a new micro-CT guided densitometric approach

Although increasing used in the preclinical testing of new anti-fibrotic drugs, a thorough validation of micro-computed tomography (CT) in pulmonary fibrosis models has not been performed. Moreover, no attempts have been made so far to define density thresholds to discriminate between aeration levels in lung parenchyma. In the present study, a histogram-based analysis was performed in a mouse model of bleomycin (BLM)-induced pulmonary fibrosis by micro-CT, evaluating longitudinal density changes from 7 to 21 days after BLM challenge, a period representing the progression of fibrosis. Two discriminative densitometric indices (i.e. 40th and 70th percentiles) were extracted from Hounsfield Unit density distributions and selected for lung fibrosis staging. The strong correlation with histological findings (rSpearman = 0.76, p < 0.01) confirmed that variations in 70th percentile could reflect a pathological lung condition and estimate the effect of antifibrotic treatments. This index was therefore used to define lung aeration levels in mice distinguishing in hyper-inflated, normo-, hypo- and non-aerated pulmonary compartments. A retrospective analysis performed on a large cohort of mice confirmed the correlation between the proposed preclinical density thresholds and the histological outcomes (rSpearman = 0.6, p < 0.01), strengthening their suitability for tracking disease progression and evaluating antifibrotic drug candidates.

Analysis of ethanol production from xylose using Pichia stipitis in microaerobic conditions through experimental observations and kinetic modelling

Hydrolysis of biomass (e.g. bagasse) leads to xylose as one of the primary sugars for fermentation to bioethanol, along with glucose. The selection of a suitable microorganism and consequently selection of suitable aeration levels for the selected microorganism plays a significant role in xylose conversion. This work focuses on the kinetics of bioethanol production from xylose using Pichia stipitis with the development of a MATLAB mathematical model (based on the combined Andrews and Levenspiel's model with oxygen limitation and inhibition terms included), considering the effects of substrate, oxygen, biomass and product concentrations on sugar utilisation, growth rate and ethanol formation. Experiments were carried out to validate the kinetic model under anaerobic and microaerobic growth conditions in a batch process. The results showed good correlation with an average R2 of 0.92 for bioethanol production, 0.95 for xylose consumption and 0.83 for biomass growth. Different aeration levels of 0.0, 0.1 and 0.2 vvm and different initial biomass concentrations of 0.3, 1.5 and 3 g L-1 were tested, in which the combination of aeration at 0.1 vvm and a biomass concentration of 3 g L-1 resulted in the highest ethanol yield and productivity of 0.45 g g-1 and 0.75 g L-1 h-1 respectively.