scholarly journals HIGH CONCENTRATIONS OF RADON AND CARBON DIOXIDE IN ENERGY-EFFICIENT FAMILY HOUSES WITHOUT HEAT RECOVERY VENTILATION

2018 ◽  
Vol 26 (1) ◽  
pp. 64-74 ◽  
Author(s):  
Gábor GÉCZI ◽  
József BENÉCS ◽  
Krisztina KRISTÓF ◽  
Márk HORVÁTH
Keyword(s):  
Carbon Dioxide ◽  
Energy Efficient ◽  
Heat Recovery ◽  
Well Being ◽  
Efficient Operation ◽  
Low Concentrations ◽  
Viable Solution ◽  
High Concentrations ◽  
Materials Used ◽  
Carbon Dioxide Co2

The most significant factors of indoor air quality – besides temperature and humidity – are the concentrations of carbon-dioxide (CO2) and radon (222Rn). Radon seepage is caused by and affected by the materials used in walls and floors, the quality of insulation, cracks and even the amount of pipes running through the walls. The amount of CO2 is predominantly affected by the biological processes of the inhabitants, and possibly by potentially faulty HVAC systems. The energy efficiency related upgrades to family homes, which often only extend to window replacements and better insulation have a significant effect and could potentially increase concentrations of both radon and CO2 which has a significant effect on the well-being of the inhabitants. Our tests conducted in Hungary have proven that by using automated heat recovery ventilation (HRV) both energy efficient operation and low concentrations of radon and CO2 are achievable. Our results prove the significance and prevalence of the issue of higher concentrations of these pollutants, and offer a viable solution.

Thymidine incorporation into Rhizobium meliloti

1979 ◽  
Vol 25 (6) ◽  
pp. 675-679 ◽  
Author(s):  
R. M. Behki ◽  
S. M. Lesley
Keyword(s):  
Carbon Dioxide ◽  
Thymidine Incorporation ◽  
Rhizobium Meliloti ◽  
Aminoisobutyric Acid ◽  
Low Concentrations ◽  
High Concentrations

Thymidine is rapidly catabolized to thymine, β-aminoisobutyric acid, and carbon dioxide by Rhizobium meliloti cells. The incorporation of labelled thymidine into the DNA of R. meliloti cells can be enhanced by the addition of low concentrations (10–20β μg/mL) of deoxyadenosine or other nucleosides (adenosine, uridine, guanosine). However, at high concentrations (>50 μg/mL) these compounds inhibit thymidine incorporation. Conditions to obtain highly radioactive DNA of Rhizobium are described.

scholarly journals Stress-induced Ethanol Production in Fresh Fruit and Vegetables

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 635d-635
Author(s):  
Charles F. Forney ◽  
Michael A. Jordan
Keyword(s):  
Carbon Dioxide ◽  
Ethanol Production ◽  
Fruits And Vegetables ◽  
Physiological Stress ◽  
Anaerobic Respiration ◽  
Highbush Blueberry ◽  
Carbon Dioxide Atmosphere ◽  
Low Concentrations ◽  
Off Flavors ◽  
High Concentrations

Fresh fruits and vegetables produce ethanol when they are held in atmospheres containing low concentrations of oxygen. Ethanol concentrations in the headspace of fresh Brassica vegetables held 24 hours in nitrogen at 20°C ranged from 5 to 110 mmol·m–3. The absence of oxygen induced anaerobic respiration and the production of ethanol in these vegetables. However, other stresses, including heat and high concentrations of carbon dioxide, can also stimulate the production of ethanol in fresh fruits and vegetables held in aerobic atmospheres. Fresh heads of broccoli dipped in 52°C water had increased concentrations of headspace ethanol 2 hours after treatment when held at 20°C in air. Concentrations were 6, 160, and 490 times greater in broccoli treated for 1, 2, or 3 minutes than in nontreated controls, respectively. Fruit of three highbush blueberry cultivars held in 25% carbon dioxide for 6 weeks at 0°C had 80 to 190 times more ethanol than fruit held in air. The 25% carbon dioxide atmosphere also induced blueberries to soften and develop off-flavors. Ethanol may be a fast and easy-to-measure indicator of physiological stress in stored fresh fruits and vegetables. Monitoring induced ethanol production could identify injurious storage environments or postharvest treatments. Possible mechanisms of stress-induced ethanol production will be discussed.

Coupling of methyl coenzyme M reduction with carbon dioxide activation in extracts of Methanobacterium thermoautotrophicum

1982 ◽  
Vol 152 (2) ◽  
pp. 840-847
Author(s):  
J A Romesser ◽  
R S Wolfe
Keyword(s):  
Carbon Dioxide ◽  
Co2 Reduction ◽  
Methanobacterium Thermoautotrophicum ◽  
Coenzyme M ◽  
Cell Extracts ◽  
Low Concentrations ◽  
Efficient Reduction ◽  
High Concentrations ◽  
Reduction Of Co2 ◽  
Stimulation Of

The stimulation of carbon dioxide reduction to methane by addition of 2-(methylthio)ethanesulfonate (CH3-S-CoM) to cell extracts of Methanobacterium thermoautotrophicum was investigated. Similar stimulation of CO2 reduction by CH3-S-CoM was found for cell extracts of Methanobacterium bryantii and Methanospirillum hungatei. The CH3-S-CoM requirement could be met by the methanogenic precursors formaldehyde, serine, or pyruvate, or by 2-(ethylthio)ethanesulfonate (CH3CH2-S-CoM), but not by other coenzyme M derivatives. Efficient reduction of CO2 to CH4 was favored by low concentrations of CH3-S-CoM and high concentrations of CO2. Sulfhydryl compounds were identified as effective inhibitors of CO2 reduction. Both an allosteric model and a free-radical model for the mechanism of CO2 activation and reduction are discussed.

scholarly journals Correlation amongst Indoor Air Quality, Ventilation and Carbon Dioxide

2017 ◽  
Vol 9 (2) ◽  
pp. 179-192 ◽  
Author(s):  
N. L. Sireesha
Keyword(s):  
Carbon Dioxide ◽  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Sick Building Syndrome ◽  
Well Being ◽  
Ventilation Rate ◽  
Indoor Contaminants ◽  
Sick Building ◽  
Carbon Dioxide Co2

The calculation of carbon dioxide (CO2)  intensities can be employed to see the quality of indoor air and ventilation. The studies undertaken till date have been distorted. The current study summaries the association amongst carbon dioxide and building air quality and ventilation, with carbon dioxide being the marker to evaluate air quality and ventilation performance. High carbon dioxide intensities may show insufficient ventilation per occupant and high indoor contaminants intensities, resulting in the Sick Building Syndrome (SBI) Symptoms. The researcher assessed the literature related to indoor air quality (IAQ), ventilation, and building-linked health issues in schools linked to CO2 discharges and recognised general indicated building-linked well-being signs found in schools. A high rise in the ventilation rate or enhancement in ventilation efficacy and/or indoor contaminant source regulation would be anticipated to reduce the occurrence of chosen signs to its optimum.

Behaviour of Releases of Carbon Dioxide From Pipelines and Vents

2014 ◽  
Author(s):  
Dan Allason ◽  
Keith Armstrong ◽  
Julian Barnett ◽  
Phil Cleaver ◽  
Ann Halford
Keyword(s):  
Carbon Dioxide ◽  
Carbon Capture ◽  
Dynamic Models ◽  
Fluid Dynamic ◽  
Experimental Studies ◽  
Carbon Capture And Storage ◽  
Research Programme ◽  
The European Union ◽  
High Concentrations ◽  
Carbon Dioxide Co2

A large Research and Development programme has been executed by National Grid to determine the feasibility of transporting carbon dioxide (CO2) by pipeline. Such pipelines would be required to form a transportation system to take the CO2 from its place of capture at an emitter’s site to a place of safe storage within a Carbon Capture and Storage (CCS) scheme. This programme received financial support from the European Union. As part of this programme, National Grid commissioned a series of experimental studies to investigate the behaviour of releases of CO2 mixtures in the gaseous and the liquid (or dense) phase. This has included simulating accidental releases in the form of punctures or ruptures of a buried pipeline and deliberate releases through different venting arrangements. This work is required, as CO2 has the potential to cause some harm to people if they are exposed to it for long enough at high concentrations. This paper gives an overview of the findings from this work and shows how the data has been used to help develop a number of the more pragmatic, predictive models for outflow and dispersion. This work complements the more theoretical studies carried out using state of the art advanced computational fluid dynamic models, employed by other UK based participants (University College London, University of Leeds, Kingston University and the University of Warwick) in the research programme.

Air-tight storage of grain; its effects on insect pests. I. Calandra granaria L.(Coleoptera, Curculionidae).

1955 ◽  
Vol 6 (1) ◽  
pp. 33 ◽  
Author(s):  
SW Bailey
Keyword(s):  
Carbon Dioxide ◽  
Respiratory Quotient ◽  
Insect Pests ◽  
Storage Conditions ◽  
Grain Storage ◽  
Low Concentrations ◽  
Cent Mortality ◽  
High Concentrations ◽  
Time Required

The responses of adult and immature Calandra granaria L. to high concentrations of carbon dioxide and low concentrations of oxygen have been determined. To bring about 100 per cent. mortality of all stages requires an increase of carbon dioxide to 40 per cent. or a decrease of oxygen to 2 per cent. The respiratory quotient of the species has been measured and it is shown that the death of the insects, under air-tight grain storage conditions, is due to the depletion of oxygen caused by the respiration of the insects and the grain and not to the accumulation of carbon dioxide. The adult insects are the most resistant stage and the first insects larvae the most susceptible. Estimates for the time required for the insects to die and for the amount of damage they cause before death are given.

scholarly journals Synergism Between Phosphine (PH3) and Carbon Dioxide (CO2): Implications for Managing PH3 Resistance in Rusty Grain Beetle (Laemophloeidae: Coleoptera)

2020 ◽  
Vol 113 (4) ◽  
pp. 1999-2006
Author(s):  
Myrna Constantin ◽  
Rajeswaran Jagadeesan ◽  
Kerri Chandra ◽  
Paul Ebert ◽  
Manoj K Nayak
Keyword(s):  
Carbon Dioxide ◽  
Reference Strain ◽  
Fold Increase ◽  
Stored Grain ◽  
Response Data ◽  
Alternative Approach ◽  
Mortality Response ◽  
High Concentrations ◽  
Carbon Dioxide Co2 ◽  
Very High

Abstract Strong resistance to phosphine (PH3) in the rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Laemophloeidae: Coleoptera) poses a serious risk to stored-grain biosecurity. Resistant populations hold risk of surviving in PH3 fumigation, particularly in storage structure that limits achieving very high concentrations of PH3, demanding the need for alternative fumigation strategies. Cofumigation with PH3 and carbon dioxide (CO2) is one alternative approach that has the potential to be used widely. CO2 fumigation of adults of strongly PH3-resistant reference strain of C. ferrugineus, for 48 h, showed that the effective concentration (LC50) of CO2 was 30.99%. This 30% level of CO2 in combination with PH3 decreased the LC50 of PH3 from 6.7 mg/liter to 0.84 mg/liter, an eightfold increase in PH3 efficacy relative to PH3 fumigation in normal air. The LC99.9 decreased from 16.2 mg/liter to 5.8 mg/liter, a 2.8-fold increase in PH3 efficacy. Comparison of mortality response data of PH3 alone and the PH3 + CO2 mixture confirmed that CO2 enhances the toxicity of PH3 synergistically in addition to exerting its own toxicity. These results were validated against three independently field-derived strains of strongly resistant C. ferrugineus that confirmed that observed enhancement in toxicity with the PH3 + CO2 mixture was consistent, irrespective of differences in resistance phenotypes and inherent tolerance levels. Results of the current study provide further opportunities to develop new commercially viable strategy to control strongly PH3-resistant C. ferrugineus.

The potential of higher plants with the phosphopyruvic acid cycle

1971 ◽  
Vol 179 (1056) ◽  
pp. 221-235 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Higher Plants ◽  
Apparent Lack ◽  
Acid Cycle ◽  
Carbon Reduction ◽  
Low Concentrations ◽  
Reduction Cycle ◽  
Artificial Environment ◽  
High Concentrations ◽  
Carbon Reduction Cycle

Optimal conditions for photosynthesis by intact higher plants are considered as those resulting in the maximum production of organic matter from carbon dioxide over a prolonged period of time. Photosynthetic yields may be limited by the ability of plants to fix and retain carbon from an atmosphere containing high concentrations of oxygen and low concentrations of carbon dioxide. In many plants photosynthetic capacity is decreased under these conditions as a result of loss of carbon from the photosynthetic carbon reduction cycle as glycollic acid. Photosynthesis is further decreased by the loss of carbon dioxide from the leaf during the further metabolism of this glycollate in photorespiratory processes. Other plants, tropical grasses in particular, are resistant to inhibition by high concentrations of oxygen. This resistance is associated with an apparent lack of photorespiration, a characteristic leaf anatomy, dimorphic chloroplasts and an ancillary mechanism for trapping carbon dioxide— the phosphopyruvic acid cycle. It is concluded that a tropical grass such as sugar cane could produce the optimum yield of organic material in an artificial environment.

EFFECT OF HIGH CONCENTRATIONS OF CARBON DIOXIDE AND OXYGEN ON THE RESPIRATION OF FULLTERM INFANTS

PEDIATRICS ◽  
1954 ◽  
Vol 14 (2) ◽  
pp. 104-113
Author(s):  
HERBERT C. MILLER
Keyword(s):  
Carbon Dioxide ◽  
Respiratory Insufficiency ◽  
Newborn Infants ◽  
Slight Effect ◽  
Asphyxia Neonatorum ◽  
Healthy Newborn ◽  
Low Concentrations ◽  
Pessimistic Attitude ◽  
Powerful Stimulus ◽  
High Concentrations

Five percent carbon dioxide added to 20% oxygen is a more powerful stimulus to respiration of healthy fullterm infants than is 100% oxygen. Fullterm infants hypoventilating as a result of exposure to low concentrations of oxygen had their minute volumes restored more rapidly and to a greater extent when 5% carbon dioxide was added to oxygen concentrations varying from 12 to 95% than when 100% oxygen was administered. The age of the infant appeared to have but slight effect on the response made to breathing 5% carbon dioxide or 100% oxygen. Infants under two or three hours of age were not tested. The value of adding carbon dioxide to air or oxygen in the treatment of "asphyxia neonatorum" has been discussed. Too little is known concerning the chemical, physiologic and anatomic changes occurring in this loosely termed condition or even in healthy newborn infants to warrant a pessimistic attitude towards the use of 5% carbon dioxide added to air or oxygen in the treatment of newborn infants with respiratory insufficiency.

scholarly journals THE CALCIUM LOOPING CYCLE STUDY FOR CAPTURING CARBON DIOXIDE APPLIED TO THE ENERGY GENERATION

2013 ◽  
Vol 12 (2) ◽  
pp. 28
Author(s):  
I. Ávila ◽  
A. Mortari ◽  
A. M. Santos ◽  
P. M. Crnkovic
Keyword(s):  
Carbon Dioxide ◽  
Energy Generation ◽  
Calcium Looping ◽  
Partial Pressure Of Co2 ◽  
Wide Availability ◽  
Co2 Sorbent ◽  
High Concentrations ◽  
Activity Decay ◽  
Carbon Dioxide Co2 ◽  
The Cost

The calcium looping process (Ca-L) is a promising technology to reduce of the carbon dioxide (CO2) emissions when applied in energy generation systems. Ca-based materials (usually limestone) are used in this process as CO2 sorbents. Thus, the CO2 capture occurs by the reversible reaction between calcium oxide (CaO) and CO2, resulting in the calcium carbonate form (CaCO3). Compared to other technologies applied to carbon sequestration process, the Ca-L offers additional advantages such: the use of fluidized bed technology that is already well established; this process occurs at high temperature, and the excess of heat generated can be recovered; the cost of limestone sorbents is low because of its wide availability. However, in the applying the Ca-L process is essential to understand the mechanism and the effect of partial pressure of CO2 in both, calcination and carbonation processes; to investigate the effect of sintering and to evaluate the sorbent activity decay. In this paper, empirical technique such as thermogravimetry is applied to investigate the reactivity of dolomite as CO2 sorbent. The effect of CO2 high concentrations in both calcination/carbonation processes is also investigated.

Sign in / Sign up

Export Citation Format

Share Document