Flow Of Humidified Air Research Articles

Insect Infestation Increases Viscosity of Biogenic Secondary Organic Aerosol.

Plant stress alters emissions of volatile organic compounds. However, little is known about how this could influence climate-relevant properties of secondary organic aerosol (SOA), particularly from complex mixtures such as real plant emissions. In this study, the chemical composition and viscosity were examined for SOA generated from real healthy and aphid-stressed Canary Island pine (Pinus canariensis) trees, which are commonly used for landscaping in Southern California. Healthy Canary Island pine (HCIP) and stressed Canary Island pine (SCIP) aerosols were generated in a 5 m3 environmental chamber at 35-84% relative humidity and room temperature via OH-initiated oxidation. Viscosities of the collected particles were measured using an offline poke-flow method, after conditioning the particles in a humidified air flow. SCIP particles were consistently more viscous than HCIP particles. The largest differences in particle viscosity were observed in particles conditioned at 50% relative humidity where the viscosity of SCIP particles was an order of magnitude larger than that of HCIP particles. The increased viscosity for the aphid-stressed pine tree SOA was attributed to the increased fraction of sesquiterpenes in the emission profile. The real pine SOA particles, both healthy and aphid-stressed, were more viscous than α-pinene SOA particles, demonstrating the limitation of using a single monoterpene as a model compound to predict the physicochemical properties of real biogenic SOA. However, synthetic mixtures composed of only a few major compounds present in emissions (<10 compounds) can reproduce the viscosities of SOA observed from the more complex real plant emissions.

Methylene blue applied to N95 respirators and medical masks for SARS-CoV-2 decontamination: What is the likelihood of inhaling methylene blue?

BackgroundGlobal shortage of personal protective equipment (PPE), as consequence of the COVID-19 global pandemic, has unmasked significant resource inequities prompting efforts to develop methods for safe PPE decontamination for reuse. The World Health Organization (WHO) in their Rational Use of PPE bulletin cited the use of a photodynamic dye, methylene blue, and light exposure as a viable option for N95 respirator decontamination. Because WHO noted that methylene blue (MB) would be applied to surfaces through which health care workers breathe, we hypothesized that little to no MB will be detectable by spectroscopy when the PPE is subjected to MB at supraphysiologic airflow rates.MethodsA panel of N95 respirators, medical masks, and cloth masks were sprayed with 5 cycles of 1,000 uM MB solution. Mask coupons were subjected to the equivalent of 120 L/min of 100% humidified air flow. Effluent gas was trapped in an aqueous solution and the resultant fluid was sampled for MB absorbance with a level of detection of 0.004 mg/m3.ResultsNo detectable MB was identified for any mask using Ultraviolet-Visible spectroscopy.ConclusionsAt 500-fold the amount of MB applied to N95 respirators and medical masks as were used for the decontamination study cited in the WHO Rational Use of PPE bulletin, no detectable MB was observed, thus providing safety evidence for the use of methylene blue and light exposure for mask decontamination.

Experimental investigations of water droplet transient phase changes in flue gas flow in the range of temperatures characteristic of condensing economizer technologies

The heating and phase changes of water droplets in 140 °C air flow humidified up to water vapor volumetric fraction of 0.3 were investigated experimentally in the context of heat recovery from flue gases with condensing economizers. The experiments were performed in experimental set-up, where atmospheric air of certain temperature and humidity passed over a water droplet suspended on thermocouple ball. It was demonstrated that initial temperature of droplet and humidity of gas flow are defining factors in transitional phase changes. However, initial droplet temperature had no effect on the equilibrium evaporation regime. The experiments performed confirmed that humidification of atmospheric air flow causes changes in magnitude of heating and phase change process of water droplets suspended in the air flow. These changes translate into increased temperature of equilibrium evaporation of the droplet, formation of favorable conditions for the condensation regime, and a change in dynamics of the droplet's geometrical parameters in initial stage of phase changes. In additionally humidified air flow, the droplet volume increased by three percent, and evaporation temperature of the droplet increased by 17 °C. Practical recommendations for water injection were produced to ensure optimal heat recovery from wet exhaust gases in a condensing economizer.

Effect of Elevated CO2 during Low Temperature Storage on the Quality Attributes of Cut Spearmint

The effect of elevated CO2 in a controlled atmospheric condition (CA) on the quality attributes of fresh-cut spearmint (Mentha spicata) during refrigerated storage is investigated in the present study. Cut stems of spearmint were exposed to the continuous flow of humidified air enriched with 0 (as a control), 5, 10 and 20% CO2 during storage at 5 °C. Weight loss, leaf colour, total phenols, antioxidant activity, aromatic profile, ascorbic acid, ethanol, ammonia and ethanol-acetaldehyde concentrations were measured before and after storage for 5, 10 and 14 days. Over time, CO2 treatments increased the weight loss, surface colour, L* (from white to black) and b* (from blue to yellow) values, but lowered a* (from green to red). When compared to fresh spearmint, the lowest CO2 concentration was able to maintain the overall colour variations. The 20% CO2 treatment showed significant declines in the total phenolic content, antioxidant potential and low appearance score after 10 days, thus its quality assessment was terminated. Vitamin C levels decreased with time in all the treatments, although the 10% and 20% CO2 treatments had the lowest levels. The toxicity of the cell structures detected by the ammonia content increased and was significantly higher in all CO2 treatments. Storage in the CA with the gas composition at 5% preserved the aromatic profiles similar to those stored in air. In conclusion, increased CO2 did not improve the storability of fresh cut spearmint held at low temperatures, and the 20% gas composition had a significant negative impact on the visual quality.

Remote Bactericidal Effect of Anatase TiO2 Photocatalytic Nanoparticles Annealed with Low-Temperature O2 Plasma.

The remote bactericidal effect of TiO2 photocatalyst, i.e., the bactericidal effect away from the photocatalyst, was successfully achieved using a humidified airflow. The TiO2 photocatalyst used was anatase-type TiO2 nanoparticles (NPs) annealed with a low-temperature O2 plasma. For comparison, anatase-type TiO2 NPs annealed in the air were used. The bacteria, Bacillus subtilis, were placed away from the TiO2 NPs. The plasma-assisted-annealed TiO2 NPs significantly inactivated 99% of the bacterial cells in 5 h, whereas the pristine and air-annealed TiO2 NPs inactivated 88-90% of the bacterial cells. The remote bactericidal effect of plasmaassisted-annealed TiO2 NPs would be attributed to a larger amount of H2O2 molecules traveled by the airflow from the TiO2 NPs. The molecules were generated by chemically reacting more photoexcited carriers on the TiO2 surface with H2O and O2 in the airflow. These photoexcited carriers originated from more oxygen-based species adsorbed and more oxygen vacancies introduced on the TiO2 surface by the plasma-assisted-annealing.

Visually guided inspiration breath-hold facilitated with nasal high flow therapy in locally advanced lung cancer

Background and purpose Reducing breathing motion in radiotherapy (RT) is an attractive strategy to reduce margins and better spare normal tissues. The objective of this prospective study (NCT03729661) was to investigate the feasibility of irradiation of non-small cell lung cancer (NSCLC) with visually guided moderate deep inspiration breath-hold (IBH) using nasal high-flow therapy (NHFT). Material and methods Locally advanced NSCLC patients undergoing photon RT were given NHFT with heated humidified air (flow: 40 L/min with 80% oxygen) through a nasal cannula. IBH was monitored by optical surface tracking (OST) with visual feedback. At a training session, patients had to hold their breath as long as possible, without and with NHFT. For the daily cone beam CT (CBCT) and RT treatment in IBH, patients were instructed to keep their BH as long as it felt comfortable. OST was used to analyze stability and reproducibility of the BH, and CBCT to analyze daily tumor position. Subjective tolerance was measured with a questionnaire at 3 time points. Results Of 10 included patients, 9 were treated with RT. Seven (78%) completed the treatment with NHFT as planned. At the training session, the mean BH length without NHFT was 39 s (range 15–86 s), and with NHFT 78 s (range 29–223 s) (p = .005). NHFT prolonged the BH duration by a mean factor of 2.1 (range 1.1–3.9s). The mean overall stability and reproducibility were within 1 mm. Subjective tolerance was very good with the majority of patients having no or minor discomfort caused by the devices. The mean inter-fraction tumor position variability was 1.8 mm (-1.1–8.1 mm;SD 2.4 mm). Conclusion NHFT for RT treatment of NSCLC in BH is feasible, well tolerated and significantly increases the breath-hold duration. Visually guided BH with OST is stable and reproducible. We therefore consider this an attractive patient-friendly approach to treat lung cancer patients with RT in BH.

Experimental Investigation of Water Droplet Phase Change in Humidi-fied Air Flow

An experimental research method and an analysis of the results of a water droplet phase change in the additionally humidified air flow are presented. The diagrams of variation of the equivalent diameter of convectively heated water droplets are presented and analysed. The influence of initial water temperature and additionally humidifying air flow on the phase change of a droplet in transient regime is experimentally substantiated.

Experimental Investigation of Water Droplet Heating in Humidified Air Flow

The droplet heat and mass transfer processes are important for liquid spraying technologies, which were investigated when applying the theoretical and numerical modelling and experimental methods. In this work, results of experimental research on the heating of water droplets in purified biofuel flue gas were presented and analyzed. In experimental investigation, the purified biofuel flue gas is replaced by additionally humidified airflow. The experiment methods and results processing are discussed and provided. Impact of air heating and additional humidification was estimated. While heating and additionally humidifying the air flow was focused on boundary conditions in condense economizers, when the flue gas temperature is 20-100°C and water vapor volume fraction is 0-0.2.

Different Vibratory Conditions Elicit Different Structural and Biological Vocal Fold Changes in an In-Vivo Rabbit Model of Phonation

Vibration of the vocal folds can disrupt the tissue and induce structural, functional, and molecular changes; the presence or absence of contact between the vocal folds during vibration can affect the type and extent of these changes. The purpose of this study was to characterize vocal fold changes following 2 hours of contact phonation or phonation without vibratory contact. Six New Zealand white breeder rabbits underwent 120 minutes of phonation with or without vibratory contact, and four served as nonphonated controls. The larynx was exposed and current was applied to the cricothyroids bilaterally to achieve vocal fold adduction while humidified airflow was delivered to induce vocal fold vibration. Laryngeal position, airflow, and stimulation levels were adjusted to obtain phonation with or without contact, and phonation was elicited for 120 minutes. Following excision, larynges were stained using Hematoxylin & Eosin, Elastica van Gieson, and Grocott's Methenamine Silver, or labeled with immunofluorescent markers for E-cadherin, CD31, CD11b, and Vimentin. All images were captured using a Nikon 90i microscope and analyzed using ImageJ. Differences between vibratory conditions and control samples were observed. There was more extensive epithelial thinning, reduced epithelial integrity and increased vascularity in the contact phonation group, while both phonatory groups demonstrated a decreased presence of mucous on the luminal surface and a decrease in elastin band thickness and lamina propria depth. Neither condition showed differences in inflammatory cell presence compared to control tissue. By showing that these two vibratory conditions result in structural changes of different types and magnitude, we have provided the first empirical evidence that vocal fold tissue is sensitive to differences in forces, and that changes in vibratory pattern can elicit different downstream biological changes within the tissue. The differences described herein are an important step toward understanding the vocal folds' potential for differential response to phonotraumatic damage following different vibratory behaviors.

The immediate effects of breathing with oscillated inspiratory and expiratory airflows on secretion clearance in intubated patients with cervical spinal cord injury.

A prospective, randomized crossover trial. To evaluate the efficacy of the combination of incentive spirometry with oscillation (OIS) and positive expiratory pressure with oscillation (OPEP) to promote secretion clearance in intubated patients with cervical spinal cord injury. Spinal cord unit, tertiary care hospital, North East Thailand. Thirteen intubated patients (C4-7, AIS score C) with secretion retention performed three interventions randomly allocated on consecutive days, a Sham deep breathing, OPEP and OPEP + OIS breathing exercise. Secretions were collected by sterile suction for 3 h before, and 3 h after, each intervention and wet weight recorded. Cardiopulmonary parameters were measured before and after each intervention. The median (IQR) secretion wet weight pre-intervention was 2.61 g (2.21, 3.85) and in the 3 h after Sham there was an increase of 1.97 g (0.6, 3.6). The increase after OPEP was 2.67 g (1.7, 3.9) and after OPEP + OIS, 4.28 g (2.4, 6.7); all the increases being significant (p ≤ 0.007). The clearance after OPEP and OPEP + OIS were both greater than Sham while OPEP + OIS was greater than OPEP (p ≤ 0.019). There were no significant changes in cardiopulmonary measures following any intervention or when compared between interventions. Deep breathing with an oscillated and humidified air flow in a combination of OIS + OPEP more than doubled secretion clearance and was more effective than OPEP or Sham deep breathing. There were no adverse effects of the procedures which were well tolerated by the patients and may be used to complement existing methods for secretion clearance.

Transient, spatially resolved desaturation of gas diffusion layers measured via synchrotron visualization

The transient 3-D visualization of the desaturation process of flooded gas diffusion layers (GDLs) is presented for the first time. Desaturation rates and pathways are reported for two commercial GDL samples, one with a PTFE treatment and the other without. On-the-fly Synchrotron X-ray CT is performed while the GDL sample is subjected to a humidified or dry air flow stream to visualize the transient desaturation. The two humidification conditions assist in separating the convective and evaporative components of the desaturation process, showing a slight contribution from the convective effect, while the majority of the desaturation is due to evaporative removal. The convective removal is found to be insufficient to fully desaturate either GDL, with water remaining trapped underneath the channel rib with the more hydrophobic GDL and within the pore space in the more hydrophilic GDL. Stop-and-shoot Synchrotron X-ray computed tomography (CT) is then used in conjunction with program-assisted segmentation to determine initial saturation water volumes. These are then combined with the desaturation times found from the on-the-fly experiments to determine desaturation rates for both GDLs. The desaturation rate using dry air flow for the more hydrophobic GDL is found to be nearly four times faster than that of the more hydrophilic GDL. Results demonstrate that an evaporative contribution is necessary for either GDL sample to reach full desaturation.

Microbial single-cell analysis in picoliter-sized batch cultivation chambers

Microfluidics has enabled various research projects in the field of microbial single-cell analysis. In particular, single-use microfluidic cultivation devices combined with automated time-lapse imaging provide powerful approaches for analyzing microbial phenomena at the single-cell level. High spatiotemporal resolution facilitates individual cell identification and tracking, delivering detailed insights into areas like phenotypic population heterogeneity, which can be highly relevant to the fate of a microbial population and may negatively impact the efficiency of biotechnological fermentations. New tools need to be developed to access the origin of population heterogeneity and understand its functional role. In this study, we present a microfluidic device for batch cultivations inside picoliter-sized cultivation chambers that can be reversibly isolated from continuous medium supply. Therefore, the cultivation broth is simply replaced by a continuous flow of humidified air, removing any medium residue along the supply channels but preserving five picoliters of cultivation medium inside the cultivation chambers in a highly parallel manner. Living cells can grow inside our microfabricated batch chambers, which can accommodate up to several hundred cells. The chamber height approximately matches the diameter of a single cell, facilitating cell growth in monolayers that are ideal for image-based cell analysis. We successfully demonstrated the growth of Escherichia coli during continuous medium perfusion and batch cultivation conditions. As expected, the cells grew exponentially under continuous medium influx until the maximum chamber capacity was reached, but when they were cultivated under batch conditions, cellular growth underwent an exponential phase, followed by a stationary phase with obvious morphological changes.

Survival in Vivo Canine Phonation Model Without Stimulation.

We describe a survival nonstimulated in vivo canine phonation model using distending laryngoscope, cramp frame, and constant humidified glottal airflow to elicit phonation. Five beagle dogs were involved in this study. One cuffed endotracheal tube was placed below the glottis through the tracheotomy and delivered humidified airflow to the glottis. Arytenoids approximation was maintained using a clamp under the distending laryngoscope. Acoustic and aerodynamic parameters were measured using synchronous signal collection system and analysis software. Vocal oscillation also was examined using stroboscope laryngeal imaging. For the nonstimulated in vivo phonation animal, the sound intensity and fundamental frequency were 78.3 ± 6.8 dB and 127.6 ± 29.2 Hz in the first experiment and 82.9 ± 6.6 dB and 175.2 ± 4.4 Hz 4 weeks later. The aerodynamic analysis revealed the mean subglottal phonation threshold pressure (PTP) and phonation threshold flow (PTF) were 8.5 ± 4.0 cmH20 and 683.0 ± 356.4 mL/s in the first experiment and 16.1 ± 8.6 cmH20 and 384.8.0 ± 230.6 mL/s in the second experiment 4 weeks later. Stroboscope image revealed sustained vocal vibration during great airflow delivery to glottis in the phonation animal model. We developed a survival nonstimulated in vivo phonation canine model that allows the study of long-term animal phonation study as its own control.

Temperature-Dependent Diffusion of H2SO4 in Air at Atmospherically Relevant Conditions: Laboratory Measurements Using Laminar Flow Technique

We report flow tube measurements of the effective sulfuric acid diffusion coefficient at ranges of different relative humidities (from ∼4 to 70%), temperatures (278, 288 and 298 K) and initial H2SO4 concentrations (from 1 × 106 to 1 × 108 molecules·cm−3). The measurements were carried out under laminar flow of humidified air containing trace amounts of impurities such as amines (few ppt), thus representing typical conditions met in Earth’s continental boundary layer. The diffusion coefficients were calculated from the sulfuric acid wall loss rate coefficients that were obtained by measuring H2SO4 concentration continuously at seven different positions along the flow tube with a chemical ionization mass spectrometer (CIMS). The wall loss rate coefficients and laminar flow conditions were verified with additional computational fluid dynamics (CFD) model FLUENT simulations. The determined effective sulfuric acid diffusion coefficients decreased with increasing relative humidity, as also seen in previous experiments, and had a rather strong power dependence with respect to temperature, around ∝ T5.6, which is in disagreement with the expected temperature dependence of ∼T1.75 for pure vapours. Further clustering kinetics simulations using quantum chemical data showed that the effective diffusion coefficient is lowered by the increased diffusion volume of H2SO4 molecules via a temperature-dependent attachment of base impurities like amines. Thus, the measurements and simulations suggest that in the atmosphere the attachment of sulfuric acid molecules with base molecules can lead to a lower than expected effective sulfuric acid diffusion coefficient with a higher than expected temperature dependence.

Early high flow nasal cannula therapy in bronchiolitis, a prospective randomised control trial (protocol): A Paediatric Acute Respiratory Intervention Study (PARIS).

BackgroundBronchiolitis imposes the largest health care burden on non-elective paediatric hospital admissions worldwide, with up to 15 % of cases requiring admission to intensive care. A number of previous studies have failed to show benefit of pharmaceutical treatment in respect to length of stay, reduction in PICU admission rates or intubation frequency. The early use of non-invasive respiratory support devices in less intensive scenarios to facilitate earlier respiratory support may have an impact on outcome by avoiding progression of the disease process. High Flow Nasal Cannula (HFNC) therapy has emerged as a new method to provide humidified air flow to deliver a non-invasive form of positive pressure support with titratable oxygen fraction. There is a lack of high-grade evidence on use of HFNC therapy in bronchiolitis.Methods/DesignProspective multi-centre randomised trial comparing standard treatment (standard subnasal oxygen) and High Flow Nasal Cannula therapy in infants with bronchiolitis admitted to 17 hospitals emergency departments and wards in Australia and New Zealand, including 12 non-tertiary regional/metropolitan and 5 tertiary centres. The primary outcome is treatment failure; defined as meeting three out of four pre-specified failure criteria requiring escalation of treatment or higher level of care; i) heart rate remains unchanged or increased compared to admission/enrolment observations, ii) respiratory rate remains unchanged or increased compared to admission/enrolment observations, iii) oxygen requirement in HFNC therapy arm exceeds FiO2 ≥ 40 % to maintain SpO2 ≥ 92 % (or ≥94 %) or oxygen requirement in standard subnasal oxygen therapy arm exceeds >2L/min to maintain SpO2 ≥ 92 % (or ≥94 %), and iv) hospital internal Early Warning Tool calls for medical review and escalation of care. Secondary outcomes include transfer to tertiary institution, admission to intensive care, length of stay, length of oxygen treatment, need for non-invasive/invasive ventilation, intubation, adverse events, and cost.DiscussionThis large multicenter randomised trial will allow the definitive assessment of the efficacy of HFNC therapy as compared to standard subnasal oxygen in the treatment of bronchiolitis.Trial registrationThe trial is registered with the Australian and New Zealand Clinical Trials Registry ACTRN12613000388718 (registered on 10 April 2013).

A microfluidic device to apply shear stresses to polarizing ciliated airway epithelium using air flow.

Organization of airway epithelium determines ciliary beat direction and coordination for proper mucociliary clearance. Fluidic shear stresses have the potential to influence ciliary organization. Here, an in vitro fluidic flow system was developed for inducing long-term airflow shear stresses on airway epithelium with a view to influencing epithelial organization. Our system consists of a fluidic device for cell culture, integrated into a humidified airflow circuit. The fluidic device has a modular design and is made from a combination of polystyrene and adhesive components incorporated into a 6-well filter membrane insert. We demonstrate the system operates within physiologically relevant shear and pressure ranges and estimate the shear stress exerted on the epithelial cell layer as a result of air flow using a computational model. For both the bronchial epithelial cell line BEAS2B and primary human tracheal airway epithelial cells, we demonstrate that cells remain viable within the device when exposed to airflow for 24 h and that normal differentiation and cilia formation occurs. Furthermore, we demonstrate the utility of our device for exploring the impact of exposing cells to airflow: our tool enables quantification of cytoskeletal organization, and is compatible with in situ bead assays to assess the orientation of cilia beating.

Ethylene is not involved in adaptive responses to flooding in the Amazonian wild rice species Oryza grandiglumis

The Amazonian wild rice Oryza grandiglumis has two contrasting adaptation mechanisms to flooding submergence: a quiescence response to complete submergence at the seedling stage and an escape response based on internodal elongation to partial submergence at the mature stage. We investigated possible factors that trigger these responses. In stem segments excised from mature O. grandiglumis plants, complete submergence only slightly promoted internodal elongation with increased ethylene levels in the internodes, while partial submergence substantially promoted internodal elongation without increased ethylene levels in the internodes. Incubation of non-submerged stem segments under a continuous flow of humidified ethylene-free air promoted internodal elongation to the same extent as that observed for partially submerged segments. Applied ethylene had little effect on the internodal elongation of non-submerged segments irrespective of humidity conditions. These results indicate that the enhanced internodal elongation of submerged O. grandiglumis plants is not triggered by ethylene accumulated during submergence but by the moist surroundings provided by submergence. The growth of shoots in O. grandiglumis seedlings was not promoted by ethylene or complete submergence, as is the case in O. sativa cultivars possessing the submergence-tolerant gene SUB1A. However, because the genome of O. grandiglumis lacks the SUB1A gene, the quiescence response of O. grandiglumis seedlings to complete submergence may be regulated by a mechanism distinct from that involved in the response of submergence-tolerant O. sativa cultivars.

Influence of pre-cutting operations on quality of fresh-cut artichokes (Cynara scolymus L.): Effect of harvest dates

The effect of harvest date on post-cutting quality of two cultivars (‘Violetto foggiano’, and ‘Catanese’) of artichokes (Cynara cardunculus L. subsp. scolymus (L.) Hayek) was studied. Artichoke heads were harvested from December 2009 to May 2010 for ‘Violetto foggiano’ (7 harvest dates), and from January to April 2010, for‘Catanese’ (4 harvest dates) from a commercial orchard in the Apulia Region, always from the same 20 randomly-chosen and labeled plants (for each cultivar). Freshly harvested artichoke heads were trimmed, cut into quarters, then stored in a humidified air flow at 5°C. Initially, and after 2, 5 and 7 days of storage, quality parameters were analyzed, including total phenol content, antioxidant activity, color attributes (outer bract surface, cut-bract surface, and cut receptacle) and visual appearance. Global color variations (ΔE*), for receptacle, cut surfaces and outer bracts, were calculated, in order to compare samples of different initial color and to evaluate variation in terms of browning. Artichokes ‘Catanese’ harvested in February showed the lowest ΔE* on cut surfaces after 7 days of storage which then increased with the proceeding of the season. Also for ‘Violetto foggiano’ after 7 days of storage, samples harvested in February showed lowest values of ΔE* on cut surfaces (bracts and receptacle), if compared to other harvesting dates. Visual quality of fresh-cut quarters decreased with the progress of the season, and for ‘Violetto foggiano’, with the decrease of the antioxidant activity. Total phenolic content and antioxidant activity were different among harvest dates for both cultivars studied, and for ‘Violetto foggiano’ showed a significant polynomial trend, denoting 2 phases of antioxidant accumulation from December to February and then from middle of March to May. The natural decline of plants at the end of production may be the reason of the poor quality of cut-artichokes in the last sampling date, and in general, considering the average temperatures at harvest, quality of fresh-cut artichokes could be positively affected by the lowest temperatures occurring in February.

Changes in color, antioxidant, and free radical scavenging enzyme activity of mushrooms under high oxygen modified atmospheres

The effects of high oxygen concentration (80% O2) on color, antioxidant enzyme and free radical scavenging activity of mushrooms (Agaricus bisporus) were investigated. High oxygen modified atmosphere chambers were designed. Mushrooms (A. bisporus) were held at 2°C for 12d in modified atmosphere chambers, linked by separate lines to continuous flow (1.67mLs−1) of humidified air (control) and 80% O2 (balanceN2). Browning of mushroom flesh and surface exposed to 80% O2 was prevented and the expected increase in membrane permeability and lipid peroxidation was delayed. Compared to the control treatment, high oxygen significantly inhibited the reactive oxygen species (ROS) such as O2− and H2O2. The corresponding oxygen radical scavenging enzyme activities including SOD, CAT and POD in 80% O2 were also higher than those in the control (P<0.05). Higher antioxidant activity was found in high oxygen treated mushrooms. The treatment with 80% O2 could be used in modified atmosphere of mushrooms to avoid browning, which was due to enhanced antioxidant and free radical scavenging enzyme activity.

Secondary pollutants from ozone reactions with ventilation filters and degradation of filter media additives

Prior research suggests that chemical processes taking place on the surface of particle filters employed in buildings may lead to the formation of harmful secondary byproducts. We investigated ozone reactions with fiberglass, polyester, cotton/polyester and polyolefin filter media, as well as hydrolysis of filter media additives. Studies were carried out on unused media, and on filters that were installed for 3 months in buildings at two different locations in the San Francisco Bay Area. Specimens from each filter media were exposed to {approx}150 ppbv ozone in a flow tube under a constant flow of dry or humidified air (50percent RH). Ozone breakthrough was recorded for each sample over periods of {approx}1000 min; the ozone uptake rate was calculated for an initial transient period and for steady-state conditions. While ozone uptake was observed in all cases, we did not observe significant differences in the uptake rate and capacity for the various types of filter media tested. Most experiments were performed at an airflow rate of 1.3 L/min (face velocity = 0.013 m/s), and a few tests were also run at higher rates (8 to 10 L/min). Formaldehyde and acetaldehyde, two oxidation byproducts, were quantified downstream of each sample. Those aldehydes (m/zmore » 31 and 45) and other volatile byproducts (m/z 57, 59, 61 and 101) were also detected in real-time using Proton-Transfer Reaction - Mass Spectrometry (PTR-MS). Low-ppbv byproduct emissions were consistently higher under humidified air than under dry conditions, and were higher when the filters were loaded with particles, as compared with unused filters. No significant differences were observed when ozone reacted over various types of filter media. Fiberglass filters heavily coated with impaction oil (tackifier) showed higher formaldehyde emissions than other samples. Those emissions were particularly high in the case of used filters, and were observed even in the absence of ozone, suggesting that hydrolysis of additives, rather than ozonolysis, is the main formaldehyde source in those filters. Emission rates of formaldehyde and acetaldehyde were not found to be large enough to substantially increase indoor concentrations in typical building scenarios. Nevertheless, ozone reactions on HVAC filters cannot be ignored as a source of low levels of indoor irritants.« less