Airtight Environment Research Articles

Removal of dichlorophenol by Chlorella pyrenoidosa through self-regulating mechanism in air-tight test environment

Microalgae are surprisingly efficient to remove pollutants in a hermetically closed environment, though its growth is inhibited in the absence of pollutants. The final pH, algal density, Chl-a content, and the removal efficiency of 2,4-dichlorophenol (2,4-DCP) by Chlorellar pyrenoidosa in a closed system were observed under different initial pH, lighting regimes, and various carbon sources. The optimal condition for 2,4-DCP removal was obtained, and adopted to observe the evolution of above items by domesticated and origin strains. The results showed that both respiration and photosynthesis participated in the degradation of 2,4-DCP, and caused the changes of pH. The photosynthesis seemed to increase the solution pH, while the respiration and the biodegradation of 2,4-DCP to decrease the solution pH. The domesticated strain achieved nearly 100% removal when initial concentrations of 2,4-DCP lower than 200 μg L−1, due to providing a appropriate but narrow pH evolution range, mostly falling between 6.5 and 7.9. The research helps to understand the mechanism of biodegradation of chlorophenol compounds by green algae.

Alternatives of storage of corn grains for the conditions of the brazilian cerrado

The storage of grains under technical conditions in favorable environment ensures grain quality and regulates the supply of raw material for food production. For this reason, the objective of this study was to evaluate the different forms of storage (aerated silo, non-aerated silo, silo bags and airtight) of grains produced in the Brazilian cerrado, over time (zero, three and six months), for different physical qualities of maize (normal grains, whole grains and broken grains). The research was conducted at the Federal University of Mato Grosso do Sul (UFMS), Chapadao do Sul Campus (CPCS), Grain Postharvest Laboratory. To determine the physical-chemical quality and the physical properties of grains over six months, samples were taken from the stored lots. Analysis of variance and comparison of means by Tukey’s test were conducted at 5% probability. The six-month storage time was the main factor contributing to the reduction of the quality of maize grains. Storage alternatives with aeration, non-aeration, bags and airtight environment did not influence the physical properties of maize grains. The broken maize grains showed the worst physical and chemical quality during storage time, while the batch of whole corn grains differ in quality during storage. It was concluded that airtight storage and storage in aerated silos were the conditions that best preserved the physical and chemical quality of maize grains over time.

Viability of Brazilwood seeds (Caesalpinia echinata Lam.) stored at room temperature in controlled atmospheres

Seed storage at room temperature is an important and low-cost tool for ex situ conservation. However, the high rates of seed deterioration could reduce the potential for storage in this condition. Therefore, the knowledge of the suitable water content for this type of storage plays a critical role. This study aimed to assess the time required to stabilize the relative humidity (RH) in sealed flasks with saturated salt solutions, with or without the introduction of seeds of Caesalpinia echinata, as well as to assess the viability of these seeds stored in environments with different hygroscopic equilibrium. The results showed that 2 and about 12 days are needed to stabilize the RH, respectively, without or with the seeds. The amount of saturated salt solutions in this airtight environment influences both the speed to equilibrate the RH and the final values of the RH. Seeds of Caesalpinia echinata tolerate drying up to 5% water content (wet basis); however, the viability of these seeds at room temperature is maintained for short periods even at low water content.

Survivorship of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae) in a Hypoxic Environment

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is a structural pest of major economic importance in the city of New Orleans, Louisiana. Hurricane Katrina made landfall along the United States Gulf coast on August 29, 2005, inundating approximately 80% of the city. Though termite colonies survived prolonged inundation, the survival mechanisms of colonies have yet to be fully understood. One hypothesis is that C. formosanus colonies survived within pockets of trapped air within their nesting system during times of flooding. This hypothesis was tested by measuring mortality of groups of 20, 40, and 60 termites in airtight environments maintained at three different temperatures. Groups of 20 termites maintained at 10, 21, and 32°C reached 100% mortality at 89.5, 52.0, and 3.5 days, respectively. Groups of 40 termites maintained at 10, 21, and 32°C reached 100% mortality at 89.5, 51.0, and 3.5 days, respectively. Groups of 60 termites maintained at 10, 21, and 32°C yielded 100% mortality at 57.5, 22.5, and 1.0 day, respectively. Field colonies of C. formosanus established before Hurricane Katrina survived up to three weeks of flooding, and our findings suggest that is possible for inundated colonies to survive this prolonged flooding by remaining within air pockets located in their nesting system until flood waters recede.

Experimental and numerical investigation of the thermal impact of defrost cycle of residential heat and energy recovery ventilators

In this study, the thermal impact of defrost cycle of both residential heat and energy recovery ventilators (HRV and ERV) was investigated using TRNSYS. The thermal efficiency patterns of the units were obtained from winter experiments, and then implemented into the existing HRV and ERV models for simulations in the context of airtight environment. Throughout the heating season, the minimum humidity of the airtight house was increased due to the reintroduction of humid indoor air/melted frost. For the HRV, simulation results indicated that its yearly demand of defrost cycle was 3.5 times higher the ERV. In other words, the HRV used in cold days could significantly deteriorate indoor air quality, which contradicted the main purpose of mechanical ventilation.

Tanning of Different Animal Skins/Hides and Study of Their Properties for Textile Application

The animal skins and hides (wet salted/fresh goat skins, sheep skins and cow hides) were tanned using a rotating drum after it was aged for four days by enclosing it in an air tight environment using polyethylene bags. The properties of goat skins, sheep skins and cow hides studied were based on moisture absorption, thickness, breaking and tearing strength. The results of the analysis indicate that a thick strong leather material was obtained from the cow hides compared to goat and sheep skins. Softer leather was obtained from the sheep compared to goat. Therefore, goat and sheep gave best leather for shoe upper and upholstery while the cow hides gave best leather for sandals and other heavy leather products.

Design of Photoionization Detector Based on the Miniature Gas Chromatography

In the space restricted airtight environment that people lives in, detecting harmful gas by miniature gas chromatography is the practical requirement at present, however, PIDs performance is key factor that restrict the application of miniature gas chromatography, the redesign of the detectors gas route in this paper aiming at improve detectors stability observably, and schemed out miniature PID with high sensitivity, low detection limit and fast response. The result of the experiment shows that the detection limit is 0.04ppm, the sensitivity is 101mv/ppm,the stability is 0.04×10-6/24h,meeting the project requirement. Keywords: photoionization detector; ionization chamber; sensitivity; detection limit;

Correlation between the hysteresis and the initial defect density of graphene

The role of the initial defects of graphene characterized by Raman spectroscopy is correlated with the physical mechanisms causing the hysteretic device characteristics of graphene field effect transistors (FETs). Fast charging related to the tunneling-induced charge exchange is found to be closely correlated with the initial defect density, while slow charging related to environmental influences such as the water redox reaction showed a weak correlation. It can be concluded that the intrinsic quality of graphene should be improved to minimize the hysteresis of graphene FETs even in an air-tight environment.

Analysis and construction of stress relief model for healthy indoor environments

Currently, the average person spends 80–90 % of their workday in an airtight indoor environment. Under such conditions, the presence of organic chemical pollutants in the air can compromise the health of workers and undermine work efficiency. Many researchers have demonstrated that plants can be used to purify the air and relive stress, essential oils can promote positive emotions and eliminate negative thoughts, and music can relieve stress by calming nerves and relaxing muscles. All of these are positively related to the release of stress and the promotion of health. This study employed three factors to construct environment-related dimensions with an influence on stress relief. We employed analytic network process to identify the environmental factors that are essential to stress relief, in conjunction with Taguchi method to determine the best combination of parameters. A model based on statistical analysis was used to verify the different benefits resulting from these changes. The proposed system provides an effective means to enhance air quality in the promotion of a comfortable, clean, and healthy environment. Our findings provide a valuable reference for the implementation of environment improvements in medical facilities, retirement homes, and office spaces.

A Novel Alternative to Cryopreservation for the Short-Term Storage of Stem Cells for Use in Cell Therapy Using Alginate Encapsulation

Efficient transport of stem/progenitor cells without affecting their survival and function is a key factor in any practical cell-based therapy. However, the current approach using liquid nitrogen for the transfer of stem cells requires a short delivery time window is technically challenging and financially expensive. The present study aims to use semipermeable alginate hydrogels (crosslinked by strontium) to encapsulate, store, and release stem cells, to replace the conventional cryopreservation method for the transport of therapeutic cells within world-wide distribution time frame. Human mesenchymal stem cell (hMSC) and mouse embryonic stem cells (mESCs) were successfully stored inside alginate hydrogels for 5 days under ambient conditions in an air-tight environment (sealed cryovial). Cell viability, of the cells extracted from alginate gel, gave 74% (mESC) and 80% (hMSC) survival rates, which compared favorably to cryopreservation. More importantly, the subsequent proliferation rate and detection of common stem cell markers (both in mRNA and protein level) from hMSCs and mESCs retrieved from alginate hydrogels were also comparable to (if not better than) results gained following cryopreservation. In conclusion, this new and simple application of alginate hydrogel encapsulation may offer a cheap and robust alternative to cryopreservation for the transport and storage of stem cells for both clinical and research purposes.

Chlorine Dioxide Gas – Sporicidal Power under Animal Bedding

Biocontainment Caging systems provide an airtight environment for animals infected with high-risk diseases. In some instances, closed-loop decontamination of these systems is preferable to whole-room decontamination. The goal of this research was to begin to quantify the amount of Chlorine dioxide gas needed to penetrate used animal bedding to kill bacterial endospores. One setting was used and some success was achieved, but with the necessity for future study to be accomplished.

Experimental study on acute respiratory distress syndrome and analysis of relevant factors in rabbits subjected to thoracic blast trauma

To reproduce acute respiratory distress syndrome (ARDS) model in rabbit induced by chest blast injury and to analyze the pathogenesis and causes of early death in order to provide the basis for the early diagnosis of lung blast injury and its early warning system to facilitate an early treatment. Sixty healthy New Zealand white rabbits were divided into six groups according to the different explosion distance with the random number table method. The survival rate and its resulting pathological changes were observed and patho physiological indexes and lung fluid content were determined at sequential time points post explosion. Shock wave pressure less than 1 210.5 mm Hg (1 mm Hg=0.133 kPa, group A, B) resulted in limited injury to the lung within grade 2 as assessed with the abbreviated injury scale (AIS). The rabbits in these groups recovered soon and survived without any complication. Shock pressure higher than 2 036.1 mm Hg (group D, E) caused severe injuries to the lung, including deep laceration , disruption of lung hilus and large hematoma in the lung, and the injury severity of lungs was assessed above grade 5 as assessed with AIS. All rabbits died within 1 hour post explosion. The groups described above failed to meet the demand of an ARDS model for the present study. Shock wave pressure at 1 917.3 mm Hg (group C) produced extensive contusion from grade 4 to grade 5 as assessed with AIS. The rabbits survived in poor general condition, and arterial partial pressure of oxygen (PaO(2)) lowered within 6 hours . Pathological examination showed extensive and constant multi focal bleeding involving more than four lobes. The alveolar wall was edematous, with partial rupture and alveolar fusion in lung tissues was observed in the group C. Alveoli were filled with inflammatory cells, and hyaline membrane was formed occasionally . Compared with control group, the wet to dry weight ratio (W/D) in lungs increased obviously (6.46±0.24 vs. 3.98±0.19, P<0.01) in group C within 6 hours postinjury. The contents of tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) in plasma and bronchoalveolar lavage fluid (BALF) were also increased distinctly compared with the control group [TNF-α (ng/L) in plasma: 328.89±6.26 vs. 62.12±2.98, TNF-α (ng/L) in BALF: 164.87±4.59 vs. 29.51±1.12; IL-6 (ng/L) in plasma: 128.51±4.13 vs. 19.32±1.53, IL-6 (ng/L) in BALF: 94.97±1.14 vs. 22.72±0.19, all P<0.05]. In an airtight environment, rabbit ARDS model can be reproduced successfully by blast injury with 1 917.3 mm Hg explosion pressure; TNF-α and IL-6 are involved in the pathogenesis and development of ARDS in blast injury. Pneumothorax as a result of lung rupture is the chief reason for early death and dysfunction of circulatory system is also an important reason in producing early death.

Factors Influencing Glabridin Stability

Glabridin, a polyphenolic isoflavan of Glycyrrhiza glabra, has shown a variety of pharmaceutical properties. We have previously studied the isolation of glabridin using macroporous resin and found that it is partially degraded, giving a dark color. To illustrate the degradation of glabridin, the present work studied the stability of glabridin under various conditions. Licorice extract containing about 20% glabridin, obtained from G. glabra by silica gel column chromatography, was used in the stability study. Seven different factors (temperature, illumination, humidity, pH, solvent, oxygen, and oxidant) were studied and content changes were determined through HPLC analysis. Except for oxygen, all the above factors had an effect on the stability of glabridin, with illumination being the main one. Moreover, the interactions between temperature and pH, temperature and humidity, and illumination and pH can promote the degradation of glabridin. In conclusion, we suggest that a dark, dry and airtight environment provides the optimized condition for the long-term storage of glabridin.

The effect of high temperature and airtight environment after pupation on the appearance of early dead eggs in the female silkworm, Bombyx mori L.

The effect of high temperature and airtight environment after pupation on the appearance of early dead eggs in the female silkworm, Bombyx mori L.

The combined toxic effects of nonpolar narcotic chemicals to Pseudokirchneriella subcapitata

This paper presents the toxicity data of 10 nonpolar narcotic chemicals on Pseudokirchneriella subcapitata (green algae) assessed by a new algal toxicity testing technique conducted under air-tight environment. Based on DO production, median effective concentration (EC50) varies from 1.73 mg/L (1-octanol) to 8040 mg/L (2-propanol). The endpoint of algal growth rate reveals similar sensitivity as that from DO production. Compared to literature data, Pseudokirchneriella subcapitata and Nitrosomonas are apparently more sensitive to nonpolar narcotics than other organisms such as minnow, daphnia, and Tetrahymena pyriformis. Furthermore, good correlations between toxic effects observed from Pseudokirchneriella subcapitata and other aquatic organisms were found. Hence, algal toxicity test can be considered as a surrogate test for estimating the toxicity of nonpolar chemicals to fathead minnow , Microtox, activated sludge, Daphina magna, and Tetrahymena pyriformis. The combined effects of 13 binary mixtures of nonpolar chemicals were investigated using both additive-index method and isobologram analysis. Overall speaking, the joint actions between these chemicals are strictly additive. Model analyses indicate that these compounds act on identical reaction sites or receptors, which verify that these chemicals are of the same toxicity mechanism (narcosis).

Qualidade fisiológica e sanitária de sementes de arroz com diferentes graus de umidade e tratadas com fungicida

O presente estudo teve por objetivo analisar o efeito do tratamento químico, com diferentes concentrações de calda fungicida, sobre a qualidade fisiológica e sanitária das sementes de arroz, durante período de seis meses de armazenamento hermético. Foram utilizadas sementes de arroz, variedades BR-IRGA 410, BRS PELOTA e EMBRAPA 7 TAIM, colhidas na região de Pelotas, RS, na safra 2001/2002. As sementes foram tratadas com o fungicida Carboxin/Thiram, na dose de 300mL.100kg-1 de sementes e, para a formulação da calda fungicida, foram empregadas doses de 1, 2 e 3% de água em mistura com fungicida. Iguais percentagens de água, sem adição do fungicida, além de uma testemunha, constituíram os sete tratamentos. O armazenamento foi realizado em garrafas de PVC (tipo "pet"), separadas por tratamento e colocadas no interior de caixas de isopor, durante 180 dias. As sementes foram submetidas aos testes de determinação do grau de umidade, germinação, vigor (frio) e sanidade, em três épocas: no pré-armazenamento (imediatamente após o tratamento), aos 90 e 180 dias. O delineamento experimental utilizado foi blocos completamente casualizados, com três repetições. Os resultados obtidos demonstram que o tratamento de sementes com o fungicida Carboxin/Thiram resultou em aumento da percentagem de germinação, para a avaliação realizada imediatamente após o tratamento, bem como foi eficiente na diminuição da incidência dos principais fungos associados às sementes de arroz. A associação entre graus de umidade e fungicida torna acelerado o processo de deterioração das sementes, armazenadas em ambientes herméticos, podendo ocasionar a morte destas em menos de 180 dias de armazenamento, especialmente quando a umidade for superior a 15%. Com o armazenamento hermético, é possível armazenar sementes por períodos de até 90 dias, com graus de umidade inferiores a 15% e se o armazenamento for realizado em períodos superiores a 180 dias, os graus de umidade das sementes devem ser inferiores a 13% para que não ocorra a diminuição da germinação.

Toxicity assessment of pesticides to Pseudokirchneriella subcapitata under air-tight test environment

This paper presents the toxicity data of seven pesticides including atrazine, parathion, dichlorvos, malathion, fenthion, 2-methyl-4-chlorophenoxyacetic acid, and pentachlorophenol on Pseudokirchneriella subcapitata based on a new algal toxicity testing technique conducted under air-tight environment. The dissolved oxygen production and the cell density were adopted as the response endpoints. Median effective concentrations (EC50) range from 0.0035 to 3.40 mg/L (DO production) and from 0.0067 to 3.12 mg/L (cell density). No-observed-effect concentration (NOEC) was determined using the Dunnett's test. NOEC values are with in the range of 0.001–1.20 mg/L. In general, the two test endpoints revealed similar sensitivities. From comparisons of literature data also based on Pseudokirchneriella subcapitata, it is clear that conventional batch tests tend to underestimate the toxicity of pesticides due to their open test environment. Closed-system tests, i.e., microplate test, respirometer test, and our BOD-bottle test, generally provide better assessment to the effects of pesticides. Data based on our test method reveals much higher toxicity (3–100 times) than that from the conventional batch tests. Furthermore, for organophosphorus insecticides, results from the present study show that Pseudokirchneriella subcapitata is less sensitive than Daphnia magna and rainbow trout, but is more susceptible than fathead minnow. The closed-system test applied in this study provides more adequate assessment for the toxicity of pesticides than the conventional batch tests.

Toxicity of chlorophenols to Pseudokirchneriella subcapitata under air-tight test environment

A closed-system algal toxicity test with no headspace was applied to evaluate the toxicity of chlorophenols to Pseudokirchneriella subcapitata. The dissolved oxygen production and the growth rate based on cell density were the response endpoints. Phenol and seven chlorophenols were tested using the above test technique. Median effective concentrations (EC50) range from 0.004 to 25.93 mg/l (based on DO production) and 0.0134 to 20.90 mg/l (based on growth rate). No-observed-effect concentration (NOEC) is within the range of 0.001–8.19 mg/l. In general, growth rate is a more sensitive response endpoint than the oxygen production, except for the case of pentachlorophenol. However, the differences in sensitivity between the two parameters were marginal. Furthermore, quantitative structure–activity relationships (QSAR’s) based on the n-octanol/water partition coefficient (log P) and the acid dissociation constant (p K a) values were established with R 2 ranged from 0.90 to 0.96. From literature data also based on P. subcapitata, the new test method is 1.65–108 times more sensitive than the conventional algal batch tests. A completely different relative-sensitivity relationship among various aquatic organisms was thus observed. The results of this study indicate that the toxicity data of volatile organic chemicals derived by conventional algal toxicity tests may severely underestimate the impact of these toxicants. Our results show that alga is very sensitive to chlorophenols compared to other aquatic organisms such as the luminescent bacteria (the Microtox test), Daphnia magna, and rainbow trout.

Piper guineense(Thonn.) as a Protectant of Melon (Citrullus vulgaris Schard) against Merchant beetle (Oryzaephilus mercator (Fauvel) (Coleoptera : Silvanidae): A Laboratory Evaluation

Laboratory experiments were conducted to assess the effectiveness of black pepper, Piper guineense (Thonn.) as a protectant of melon, Citrullus vulgaris Schard against fourth instar larvae of the Merchant beetle, Oryzaephilus mercator (Fauvel) in each of two environments (aerated and airtight). In the aerated environment, the means of O. mercator emergence, were 19.84 +0.46, 9.49 + 0.90, 6.40 + 0.34, 3.46 + 1.25, 1.49 + 0.90, 0.00 + 0.00, and 0.00 +0.00, for the control, 0.25g, 0.5g, 0.75g, 1g, 2g, and 3g pepper 120g melon, respectively, while the corresponding means in the airtight environment were 18.42 + 1.06, 8.86 ±3.88, 4.93 ± 0.26, 2.78 ± 2.82, 1.09 ± 0.58, 0.00 ± 0.00, and 0.00 ±0.00. Student-Newman-Keuls Procedure indicated that in both environments, all the six rates of black pepper significantly reduced O. mercator emergence compared with the control treatment. Total control was obtained at 2g pepper/20g melon and 3g pepper/20g melon treatments in both environments. The LC50 and LC90 of black pepper against O. mercator were 0.27g and 0.9~g pepper 120g melon, respectively, in the aerated environment and 0.30g and 0.93g pepper/20g melon, respectively, in the airtight environment. Thus the black pepper, which is readily available throughout the year in the West African region, relatively cheap, non-toxic, and amenable to safe handling by illiterate peasant farmers, provides a good alternative to synthetic insecticides in the control of O. mercator since resistance to most of these chemicals had been reported.

Inhibition of reproductive growth of Arabidopsis in airtight vessels

Airtight vessels have various advantages for space experiments. However, Arabidopsis thaliana plants scarcely produced seeds when grown in such vessels. The mechanism by which reproductive growth is inhibited in airtight vessels was studied. The length of the flower stalk was shorter when the plants were grown in airtight vessels. Thus, there was a possibility that the inhibition of reproductive growth was due to the inhibition of vegetative growth. However, even when the plants which has grown under non-airtight conditions and has reached to the flowering stage were transferred to airtight vessels, silique formation was inhibited, suggesting that the airtight environment directly influences reproductive growth. In airtight vessels, anther dehiscence was inhibited, which appears to be the cause of inhibition of silique formation and seed development. Reproductive growth recovered when silica gel was added to the vessels. These results suggest that in airtight vessels, high humidity causes a suppression of anther dehiscence, resulting in the inhibition of reproductive growth. Therefore, the control of humidity by ventilation should be taken into consideration in designing a growth chamber for space experiments.