Carbon dioxide and routine cultures in the diagnostic laboratory.

Chemical Controls on the Dissolution Kinetics of Calcite in Seawater

1.1 Carbon dioxide 1.1.1 Significance Theoretical and experimental investigations of weakly bound molecular complexes are of fundamental importance for understanding of molecular interactions responsible for properties of condensed phases. The carbon dioxide clusters provide a simple model for such studies. Carbon dioxide has been a subject of many papers in recent years. Some deal with its role in the biosphere, mainly the greenhouse effect. The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap energy from the sun. Without these gases, heat would escape back into space and Earth’s average temperature would be lower. Other investigations deal with the significance of carbon dioxide for the nutrition for plants, the supercritical carbon dioxide as a green solvent for extraction and synthesis and the existance of carbon dioxide in the atmospheres of Mars and Venus. 1.1.2 Previous Investigations The carbon dioxide dimer was first detected in 1966 by Leckenby et al.[?]. The slippedparallel( C2h - geometry) structure of the carbon dioxide dimer was shown experimentally in references [?] - [?](high-resolution infrared) and [?](Raman studies) to be the stable one. That the structure of the dimer is slipped-parallel(C2h - geometry) was shown in [?] as a result of quantum-chemical calculations. The dimerisation equilibrium constant was evaluated using partition functions [?]. 1.1.3 Dimer formation A new method is developed to calculate the equilibrium constant of weak dimer complexes and the life time of the dimer in the gas phase. Actually it is not an easy task to define when approaching monomers form a dimer. In the new method the defined time correlation function from the molecular dynamics simulations shows a slow decay corresponding to real dimers and a fast decay corresponding to unstable collisions. The results obtained for the carbon dioxide dimerization are compared to results obtained by two other methods using partition function and second virial coefficient. A possible application is to predict the dimer carbon dioxide concentration in the atmospheres of Mars and Venus. 1.2 Rebinding dynamics of nitric oxide to the V68F Myoglobin mutant In connection with the work on rebinding molecular dynamics of nitric oxide to the V68F Myoglobin mutant I would like to emphasize that the study of reactive processes in chemically and biologically relevant systems is a topic of much current interest. For fast reactions (proton transfer, ligand rebinding) computer simulations are a useful means to investigate and understand the energetics and dynamics of chemical reactions. A new surface-crossing algorithm suitable for describing bond-breaking and bond-forming processes in molecular dynamics simulations is presented in [?]. The method is formulated for two intersecting potential energy manifolds which dissociate to different adiabatic states. During simulations, crossings are detected by monitoring an energy criterion. If fulfilled, the two manifolds are mixed over a finite number of time steps, after which the system is propagated on the second adiabat and the crossing is carried out with probability one.

The principal mechanisms for the geologic sequestration of carbon dioxide in deep saline aquifers include \ngeological structural trapping, hydrological entrapment of nonwetting fluids, aqueous phase dissolution and \nionization, and geochemical sorption and mineralization. In sedimentary saline aquifers the dominant \nmechanisms are structural and dissolution trapping, with moderate to weak contributions from hydrological \nand geochemical trapping; where, hydrological trapping occurs during the imbibition of aqueous solution into \npore spaces occupied by gaseous carbon dioxide, and geochemical trapping is controlled by generally slow \nreaction kinetics. In addition to being globally abundant and vast, deep basaltic lava aquifers offer \nmineralization kinetics that make geochemical trapping a dominate mechanism for trapping carbon dioxide in \nthese formations. For several decades the United States Department of Energy has been investigating \nColumbia River basalt in the Pacific Northwest as part of its environmental programs and options for natural \ngas storage. Recently this nonpotable and extensively characterized basalt aquifer is being reconsidered as a \npotential reservoir for geologic sequestration of carbon dioxide. The reservoir has an estimated storage \ncapacity of 100 giga tonnes of carbon dioxide and comprises layered basalt flows with sublayering that \ngenerally alternates between low permeability massive and high permeability breccia. Chemical analysis of \nthe formation shows 10 wt% Fe, primarily in the +2 valence. The mineralization reaction that makes basalt \naquifers attractive for carbon dioxide sequestration is that of calcium, magnesium, and iron silicates reacting \nwith dissolved carbon dioxide, producing carbonate minerals and amorphous quartz. Preliminary estimates of \nthe kinetics of the silicate-to-carbonate reactions have been determined experimentally and this research is \ncontinuing to determine effects of temperature, pressure, rock composition and mineral assemblages on the \nreaction rates. This study numerically investigates the injection, migration and sequestration of supercritical \ncarbon dioxide in deep Columbia River basalt formations using the multifluid subsurface flow and reactive \ntransport simulator STOMP-CO2. Simulations are executed on high resolution multiple stochastic realizations \nof the layered basalt systems and demonstrate the migration behavior through layered basalt aquifers and the \nmineralization of dissolved carbon dioxide. Reported results include images of the migration behavior, \ndistribution of carbonate formation, quantities of injected and sequestered carbon dioxide, and percentages \nof the carbon dioxide sequestered by different mechanisms over time.

This paper summarizes the results of an investigation on carbon dioxide (CO2) sequestration in concrete. Carbon dioxide (CO 2 ) is the predominant greenhouse gas resulting from human industrial Activities. A significant fraction of CO 2 discharged into the atmosphere comes from Industry point sources. Cement production alone contributes approximately 5% of global CO 2 emissions. This emitted carbon dioxide, however, can be partially recycled into concretes through early age curing to form thermodynamically stable calcium carbonates. The carbonation reaction between carbon dioxide and appropriate calcium Compounds results in permanent fixation of the carbon dioxide in a thermodynamically stable calcium carbonate. Carbon dioxide and water can be found in almost every environment and thus all concretes will be subjected to carbonation. This paper summarizes a recent study on optimization of concrete and the flue gas carbon dioxide collected from cement kiln can be beneficially utilized in concrete production to reduce carbon emission, accelerate early strength, and improve durability of the products. Cement industry contributes to 5% of global CO2 emissions. To mitigate pollution, there is a need of CO2 sequestration into stable forms. Present research focusses on CO2 being channelized towards an important construction practice. This paper summarizes the potential of CO2 absorption in concrete. In reference to cement content, carbon uptake in 4-hour carbonation reaches 28 days strength achieved by conventional curing method.

To quantify the greenhouse gas emissions from rivers and lakes, environmental conditions, water qualities, carbon dioxide and methane emissions were determined in the up-, mid- and down-stream areas of Kaoping River and Chenching Lake. Atmospheric carbon dioxide concentrations were 292-430, 295-453, 328-476 and 302- 449 ppm, respectively, and atmospheric methane concentrations were 1.70-2.09, 1.71-3.10, 1.70-2.86 and 1.18- 3.60 ppm, respectively. By using the headspace method with brown color bottle, carbon dioxide concentrations were determined as 198-5,437, 1,077-8,584, 3,977-10,839 and 1,537-9,902 ppm, respectively, and methane concentrations fell into the range of 2.8-231.0, 38.9-881.2, 75.3-983.1 and 31.5-4,321.5 ppm, respectively. By using the static-chamber method, carbon dioxide emission rates were -51.3-209.3, -9.6-232.4, -25.7-265.8 and -155.9-217.1 mg m^(-2) h^(-1), respectively, and methane emission rates were 0.05-1.52, 0.05-4.50, 0.26-6.12 and 0.02- 2.68 mg m^(-2) h^(-1), respectively. There is a positive correlation between methane concentration with the headspace method and emission rate with the static-chamber method. Methane emission was very significantly negativelycorrelated with dissolved oxygen (DO), significantly negatively-covrelatived with redox potential (Eh), and very significantly positively-correlated with methane concentration, carbon dioxide concentration using the head-space method, total alkalinity (ALK), and conductivity (CD) in the tested river. Carbon dioxide emission in the tested river had positive correlation with methane concentration by the head-space method. Methane emission in the test lake had very significantly positive correlation with alkalinity (ALK), significantly positive correlation with redox potential (Eh), biological oxygen demand (BOD) and chemical oxygen demand (COD). The annual carbon flows from Kaoping River into ocean from 2003 to 2007 were estimated between 3.7 × 10^5 and 1.7 × 10^6 tons.

Zeolites have long been considered as excellent candidate materials for gas separation and purification. Most of the worldwide industrial adsorption applications of molecular sieve zeolites utilize zeolites X, A and Y. Chabazite zeolite however, has pore dimensions between those for zeolites X, A and Y and hence has promising separation features for specific application but has not been utilized in any major industrial separation or purification applications to date. Some early work on alkali-exchanged chabazites revealed a diminished porosity and surface area due to pore blockage. This initial work was based on limited experimental data and preliminary analytical techniques and analysis. As a result, this initial pessimistic assessment of the merits of chabazite zeolite has led to a loss of interest in this material for adsorption applications. In this study, a pure phase chabazite was synthesized and ion-exchanged to produce potassium chabazite (KCHA), sodium chabazite (NaCHA) and lithium chabazite (LiCHA). Attempts were successful to produce a fully exchanged potassium chabazite, which is a unique product that has not been reported in the literature to date. The adsorption of nitrogen and carbon dioxide was studied since these gases are component of flue gas and the application to which chabazites were to be directed was CO2 capture form flue gas. Adsorption equilibrium isotherms for CO2 and N2 were measured at pressures up to 101.3 kPa and temperatures of 273, 303 and 333 K. More importantly, this work focused on determining fundamental properties of adsorbate-adsorbent interactions which require low pressure measurements hence low pressure isotherms, down to 0.001 kPa, were measured. These data provide valuable information to study the adsorption behavior in the Henry’s law region. The results showed that porosity characterization of KCHA using the conventional approach of nitrogen at 77 K reveals a surface area of only 17.82 m2 g-1 and a diminished pore volume (by density functional calculation) of 0.005 cm3 g-1, compared to 584.4 m2 g-1 and 0.214 cm3 g-1 using carbon dioxide at 273 K, respectively, calculated from the revised Toth model and CO2 isotherm data at 273K. These findings strongly suggested that KCHA is a highly porous adsorbent, in spite of the large size of K+ ions which block access of the N2 molecules to the pore space. It is concluded that traditional methods of characterization are not suitable in the case of pore blockage leading to incorrect interpretation of adsorbent properties. It was initially hypothesized that carbon dioxide molecules enjoy large freedom within the zeolite pores, however, virial plots developed from equilibrium isotherms showed anomalous behavior for carbon dioxide adsorption at 273 K on NaCHA and KCHA at loadings lower than 1.5 gmole kg-1, which correspond to pressure of about 0.15 kPa. This suggested that carbon dioxide molecules were not at true equilibrium condition, but rather were subject to steric hindrance due to partial pore blockage. Adsorbed phase densities calculated from van der Waals constants confirmed the pore blockage phenomenon on KCHA, however, it also reveals a slight blockage against nitrogen molecules on NaCHA. On the synthesized chabazites, carbon dioxide affinities and heats of adsorption were considerably higher than those for nitrogen for which their adsorption equilibria differ significantly due to screening against nitrogen molecules in KCHA and partially in NaCHA. Carbon dioxide entropy measurement revealed a concave trend, demonstrating an appreciable loss of degrees of freedom within increase in loading. Carbon dioxide desorption isotherms showed low pressure hysteresis at 273 K with residuals of 0.37 and 0.57 molecule cavity-1 on NaCHA and KCHA, respectively, at pressures lower than 0.05 kPa. This outcome confirmed the pore blockage occurrence suggesting a low pressure encapsulation. The combined use of the statistical theory of the radial distribution function (rdf) and the theory of the perfect 3D lattice gas to describe the encapsulation process underestimated the number of accommodated molecules compared to the experimental results. The individual implementation of Lennard-Jones and quadrupolar potentials to describe the adsorbate-adsorbate and adsorbate-host interactions, respectively, affected the performance of the models.

To investigate carbon dioxide and methane emissions from the river water, mercuric chloride was added to the water for retarding microbial activities during the period from water sampling to laboratory measurement. But the effects of mercuric chloride on emissions of these green house gases from water remain unknown. Therefore, carbon dioxide and methane emissions from water of Tamsui River with different amounts of saturated mercuric chloride solution (69 mg/mL at 20℃) were determined at 25℃ for 6 days. Carbon dioxide and methane emissions decreased with increasing amount of saturated mercuric chloride solution added from 50 to 600 μL (3.45-41.4 mg) in 100 mL water. The gas emissions decreased slightly when the amount of saturated mercuric chloride was higher than 200 μL (13.8 mg). Carbon dioxide and methane emissions decreased linearly with the amount of saturated mercuric chloride supplemented between 0 and 100 μL (0-6.9 mg). The effect of bottle color on the carbon dioxide and methane emissions was studied with colorless and brown-colored bottles. Water in the brown-colored bottles had higher carbon dioxide and methane emissions than in the colorless bottles. The downstream area of Tamsui River had the highest carbon dioxide and methane emissions, followed by the middle-stream area, and the upstream area was the lowest due to the high pollution in the downstream area. Therefore, addition of 100 μL saturated mercuric chloride solution (6.9 mg) in 100 mL of water to retard the microbial activities after sampling in the fields for measurement of greenhouse gases emissions from water is a feasible method.

The geologic formations, which can be utilized for CO 2 storage include: deep saline aquifers, oil and gas reservoirs and coal bed reservoirs. The fluids in the subsurface fill the porous rock as occurs with water, oil, natural gas, carbon dioxide, among others. In these formations, carbon dioxide is stored by different trapping mechanisms; the exact mechanism depends on the type of rock. The main mechanisms are: hydrodynamic trapping, solubility trapping and mineral trapping. Among the geologic formations, oil reservoirs are strong candidates to be used in the reduction of carbon dioxide in the atmosphere due to the technological knowledge acquired by the oil industry. These reservoirs are proved geologic traps with capacity to retain fluids and gases for long term. The CO 2 injection technique for enhanced recovery is a common practice in the oil industry and it can be used in carbon sequestration. The storage of some part of the injected gas in reservoirs submitted to Enhanced Oil Recovery operations is a direct consequence of CO 2 utilization since the gas produced with the oil be captured and re-injected in the reservoir. This work presents a global dynamic model of the carbon sequestration process in enhanced oil recovery operations in a typical mature oil reservoir aiming to quantify the real contribution of the stored gas.

افزایش غلظت دی اکسید کربن و سایر گازهای گلخانه ای در سال‌های اخیر و در نتیجه آن افزایش دمای کره زمین ممکن است بر چرخه های بیوشیمیای عناصر در خاک تأثیر گذار باشد. به منظور بررسی تأثیر دما و غلظت گاز دی اکسید کربن و اثر متقابل آنها بر شکل‌های نیتروژن محلول خاک آزمایشی در قالب طرح کاملا تصادفی با آرایش فاکتوریل با دو سطح دمایی 25 و 35 درجه سانتیگراد و دو سطح غلظت گاز دی اکسید کربن به مقدار 350 و 750 میلیگرم در لیتر بر روی یک خاک آهکی با یک درصد کود گاوی پوسیده به همراه 200 کیلوگرم در هکتار کود اوره انجام شد. تغییرات غلظت شکل‌های نیتروژن محلول خاک شامل نیتروژن محلول کل، نیتروژن معدنی محلول ، نیتروژن آلی محلول، مجموع نیترات و نیتریت و آمونیوم در طی 60 روز بررسی شد. نتایج نشان داد که تأثیر افزایش غلظت دی اکسید کربن در دماهای 25 و 35 درجه سانتیگراد بر غلظت شکل‌های مختلف نیتروژن محلول خاک متفاوت بود. در دمای 25 درجه سانتیگراد افزایش غلظت دی اکسید کربن موجب افزایش نیتروژن آلی محلول و کاهش نیتروژن معدنی محلول و مجموع نیتریت و نیترات گردید و بر مقدار نیتروژن محلول کل تأثیر معنی داری نداشت. در حالی که در دمای 35 درجه سانتیگراد افزایش غلظت دی اکسید کربن از 350 به 750 میلیگرم در لیتر غلظت نیتروژن محلول کل، نیتروژن معدنی محلول و مجموع نیتریت و نیترات را افزایش داد و بر مقدار نیتروژن آلی محلول تأثیر معنی داری نداشت. افزایش غلظت دی اکسید کربن در دماهای بالاتر موجب افزایش تجزیه فرم‌های آلی نیتروژن گردید. در بررسی روند تغییرات غلظت شکل‌های نیتروژن محلول در طی زمان نشان داده شد که تغییرات نیتروژن آلی محلول نسبت به سایر شکل‌ها در طی زمان زیادتر بود. افزایش غلظت دی اکسید کربن در دمای 35 درجه سانتیگراد موجب وقوع زود هنگام حداکثر و حداقل غلظت نیتروژن آلی محلول نسبت به سایر تیمارها در طی زمان گردید. نتایج این تحقیق نشان داد که افزایش دما به همراه افزایش دی اکسید کربن موجب تحریک و افزایش سرعت واکنش‌های بیوشیمیایی نیتروژن در خاک گردید.

To investigate the effect of mercuric chloride on carbon dioxide and methane emissions from water, different amounts of saturated mercuric chloride were added to the water of Kaoping River and Chenching Lake, and incubated at 25℃ for 6 days. Carbon dioxide and methane emissions decreased with increasing the amount of saturated mercuric chloride (69 mg mL(superscript -1) at 20℃) addition from 50 to 600 μL (3.45-41.4 mg) in 100 mL of water. Carbon dioxide and methane emissions decreased slightly when the amount of saturated mercuric chloride was higher than 200 μL (13.8 mg). Carbon dioxide and methane emissions had linear correlation with the amount of saturated mercuric chloride supplement between 0 and 100 μL. The brown color bottle had higher carbon dioxide and methane emissions from water than those of colorless bottle. The down-stream area of Kaoping River had the highest carbon dioxide and methane emissions, followed by the mid-stream area, and the upstream area and Chenching Lake had the lowest values. High carbon dioxide and methane emissions at the down-stream area might be due to high pollution. Therefore 100 μL of saturated mercuric chloride (6.9 mg) added in 100 mL of water to retard the microbial activity is a feasible method during the measurement of greenhouse gases emissions from water.

The evolution of natural systems that feed and sustain human populations, and indeed the evolution of modern society, has occurred in the context of a moderate and stable climate. Therefore, recent trends in climate change, most likely caused by increasing concentrations of carbon dioxide and other radiative trace gases in the atmosphere, and the expected consequent global warming, are now a major concern. Carbon emissions from energy systems are considered one of the major contributors to climate change and are the focus of all studies on the prevention of climate changes and adaptation strategies. Two global energy scenarios (each with several options) are analysed in this paper: from a dynamic–as–usual concept to a more advanced concept with the goal of stabilising carbon dioxide concentrations in the atmosphere (equivalent to about a 60% reduction of carbon emission compared with today's level). It is shown that the stabilisation approach will require dramatic changes in energy systems: the share of non–carbon fuels will increase to about three quarters of the total primary energy consumption, which will itself grow by a factor of two by the middle of the next century. Surprisingly, the implementation costs turn out to be approximately the same for all scenarios (taking into account possible errors in the cost appraisals for several decades ahead). However, the cost distributions between energy production and use are quite different. Globally, these costs are 3–4% of the GNP, but for developing countries the share of energy investments is, on average, about 7–8% of the GNP, which is cause for concern and will greatly hamper economic and social progress in the Third World. The introduction of energy taxes or carbon taxes in developed countries and the raising of 'global energy funds' could help developing countries to overcome these difficulties. It is supposed that such a policy would stimulate economic growth in developing countries and, as a feedback, overlap the GNP losses in developed countries. The paper attempts to evaluate an optimal strategy for reducing carbon emissions for the next couple of decades, when large uncertainties surround global warming, and to show ways of establishing 'no–regret' policy.

Cell division and cell wall synthesis are closely linked complex phenomena and play a crucial role in the maintenance and regulation of bacterial virulence. Eukaryotic-type Ser/Thr kinases reported in prokaryotes, including that in group A Streptococcus (GAS) (Streptococcus pyogenes Ser/Thr kinase (SP-STK)), regulate cell division, growth, and virulence. The mechanism of this regulation is, however, unknown. In this study, we demonstrated that SP-STK-controlled cell division is mediated under the positive regulation of secretory protein that possesses a cysteine and histidine-dependent aminohydrolases/peptidases (CHAP) domain with functionally active cell wall hydrolase activity (henceforth named as CdhA (CHAP-domain-containing and chain-forming cell wall hydrolase). Deletion of the CdhA-encoding gene resulted in severe cell division and growth defects in GAS mutants. The mutant expressing the truncated CdhA (devoid of the CHAP domain), although displayed no such defects, it became attenuated for virulence in mice and highly susceptible to cell wall-acting antibiotics, as observed for the mutant lacking CdhA. When CdhA was overexpressed in the wild-type GAS as well as in heterologous strains, Escherichia coli and Staphylococcus aureus, we observed a distinct increase in bacterial chain length. Our data reveal that CdhA is a multifunctional protein with a major function of the N-terminal region as a cell division plane-recognizing domain and that of the C-terminal CHAP domain as a virulence-regulating domain. CdhA is thus an important therapeutic target.

Objective To evaluate the accuracy of continuous noninvasive partial pressure of carbon dioxide monitoring in the old diabetic patients undergoing general anesthesia. Methods Sixty-six old diabetic patients of both sexes, aged 65-76 yr, weighing 49-95 kg, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, undergoing elective surgery under general anesthesia, were included in this study.Transcutaneous partial pressure of carbon dioxide(TcPCO2)was monitored by a noninvasive transcutaneous carbon dioxide monitor.Arterial blood samples were collected at 30 and 60 min after endotracheal intubation, partial pressure of arterial carbon dioxide(PaCO2)was monitored, and TcPCO2 and end-tidal pressure of carbon dioxide(PETCO2)were recorded.Bland-Altman analysis was used to measure the agreement. Results At 30 min after intubation, the results of Bland-Altman analysis showed that the mean difference between PaCO2 and TcPCO2 was 1.3, 95% confidence interval(CI)was 1.0-1.6, and the limit of agreement was -1.1-3.7; the mean difference between PaCO2 and PETCO2 was -3.2, 95%CI: -3.6--2.8, and the limit of agreement was -6.6-0.2.At 60 min after intubation, the results of Bland-Altman analysis showed that the mean difference between PaCO2 and TcPCO2 was 1.4, 95% CI was 1.1-1.7, and the limit of agreement was -1.0-3.4; the mean difference between PaCO2 and PETCO2 was -3.1, 95%CI was -3.5--2.7, and the limit of agreement was -6.7-0.5.The repeatability coefficients of PaCO2, TcPCO2 and PETCO2 were 2.1, 2.3 and 2.3, respectively, at 30 and 60 min after intubation. Conclusion Continuous noninvasive partial pressure of carbon dioxide monitoring provides good accuracy and can be used as an alternative to PaCO2 monitoring, and the accuracy is higher than that of PETCO2 for the old diabetic patients undergoing general anesthesia. Key words: Carbon dioxide; Monitoring, physiologic; Diabetes mellitus; Anesthesia, general

The work described in this Thesis has been carried out within the Erasmus Mundus framework for Sustainable Industrial Chemistry (SINCHEM). The work concentrates on the possible utilisation of carbon dioxide as a solvent and as a starting material. Chapter 1 introduces carbon dioxide and its utilisation. In addition, the 12 Principles of CO2 Chemistry are presented, as well as continuous flow chemistry and self-optimising reactors. The relevant aspects of these reactors are discussed further in Chapter 2. The results of the research are presented in Chapters 3-6. A self-optimising reactor with FT-IR analysis was employed for the methylation of alcohols as explained in Chapter 3. Chapters 4-6 concentrate on N-alkylation reactions. In Chapter 4, the reactivity between aniline, tetrahydrofuran and dimethyl carbonate in supercritical carbon dioxide is discussed. This research led to the discovery of novel transformations. In Chapters 5 and 6, methanol was employed to methylate amines. A ruthenium triphosphate catalyst, which can produce methanol from carbon dioxide and hydrogen, was used to catalyse the reactions between methanol and aliphatic amines, as described in Chapter 5. Also the cyclisation and subsequent methylation of amino alcohols was studied. This reactivity is also the topic of Chapter 6, where γ-alumina was used as catalyst and supercritical carbon dioxide as solvent. Finally, Chapter 7 summarises the work described in this Thesis and evaluates the progress made towards achieving the aims that are introduced at the end of Chapter 1. One of these aims is to evaluate the work carried out in this Thesis according to the 12 principles of CO2 Chemistry. This evaluation is shown in Chapter 7.

Efficiency Potential of Solar Thermochemical Reactor Concepts with Ecological and Economical Performance Analysis of Solar Fuel Production