Sodium Bicarbonate Concentration Research Articles

Effects of exposure to calves persistently infected with bovine viral diarrhea virus type 1b and subsequent infection with Mannheima haemolytica on clinical signs and immune variables: Model for bovine respiratory disease via viral and bacterial interaction1,2

The objective was to determine effects of an intratracheal Mannheimia haemolytica challenge after 72-h exposure to bovine viral diarrhea virus type 1b (BVDV1b) persistently infected (PI) calves on serum antibody production, white blood cell count (WBC), cytokine concentrations, and blood gases in feedlot steers. Twenty-four steers (initial BW = 314 +/- 31 kg) were randomly allocated to 1 of 4 treatments (6 steers/treatment) arranged as a 2 x 2 factorial. Treatments were 1) steers not exposed to steers PI with BVDV nor challenged with M. haemolytica (control; CON); 2) steers exposed to 2 steers PI with BVDV for 72 h (BVD); 3) steers intratracheally challenged with M. haemolytica (MH); and 4) steers exposed to 2 steers PI with BVDV for 72 h and challenged with M. haemolytica (BVD+MH). There were 12 h between exposure to PI steers and challenge with M. haemolytica. Rectal temperature was increased (P < 0.001) for MH and BVD+MH during the initial 24 h after the M. haemolytica challenge. For MH and BVD+MH, total WBC count was increased (P < 0.01) at 36 h post M. haemolytica challenge compared with CON, whereas in BVD steers, WBC count was decreased (P < 0.01). Total lymphocyte count was increased (P = 0.004) during the initial 72 h post BVDV exposure for the BVD and BVD+MH groups compared with MH and CON, and this difference remained at 96 h post M. haemolytica challenge. An increased (P < 0.001) total neutrophil count was observed during the initial 36 h for the MH group and at 72 h for the BVD+MH challenge group. Interleukin 1beta, IL-6, and tumor necrosis factor alpha (TNFalpha) concentrations were greater (P <or= 0.04) in BVD steers than steers not exposed to BVDV, and interferon gamma, IL-1beta, and TNFalpha were greater (P <or= 0.02) in MH steers than in steers not challenged with M. haemolytica. There were BVD x MH interactions (P <or= 0.04) for plasma carbon dioxide, carbonic acid, and sodium bicarbonate concentrations. Challenge with M. haemolytica decreased carbon dioxide, carbonic acid, and sodium bicarbonate concentrations to a greater extent when steers were not exposed to PI steers compared with steers exposed to BVDV. We conclude that the challenge model was successful at inducing bovine respiratory disease (BRD) associated with BVDV and M. haemolytica. Understanding the physiological changes in morbid animals will lead to improved strategies for decreasing severity and economic losses associated with BRD.

A kinetic study of autohydrogenotrophic denitrification at the optimum pH and sodium bicarbonate dose

In this study the kinetics of autohydrogenotrophic denitrification was studied under optimum solution pH and bicarbonate concentration. The optimal pH and bicarbonate concentration were firstly obtained using a design of experiment (DOE) methodology. For this purpose a total of 11 experiments were carried out. Sodium bicarbonate concentrations ranging of 20–2000 mg/L and pH values from 6.5 to 8.5 were used in the optimization runs. It was found that the pH has a more pronounced effect on the denitrification process as compared to the bicarbonate dose. The developed quadratic model predicted the optimum conditions at pH 8 and 1100 mg NaHCO 3/L. Using these optimal conditions, the kinetics of denitrification for nitrate and nitrite degradation were investigated in separate experiments. Both processes were found to follow a zero order kinetic model. The ultimate specific degradation rates for nitrate and nitrite remediation were 29.60 mg NO 3 - –N/g MLVSS/L and 34.85 mg NO 3 - –N/g MLVSS/L respectively, when hydrogen was supplied every 0.5 h.

Salts Application for Suppressing Potato Early Blight Disease

Salts Application for Suppressing Potato Early Blight DiseaseThe suppressive effect of sodium and calcium salts applied individually or combined with the yeastSaccharomyces cerevisiaeagainstAlternaria solanithe causal agent of early blight disease of potato was evaluated under laboratory, greenhouse and field conditions.In vitrotest a complete inhibition in fungal growth was observed at concentration of 30 mg/ml of both sodium bicarbonate and calcium chloride. The commercial backing yeastS. cerevisiae(CBY) enhanced the inhibitory effect of tested salts reflected in increasing mycelial fungal growth reduction when combined at the rate of 1:1 at each concentration tested. In pot experiment, under artificial infestation with pathogenic fungus, application of sodium bicarbonate or calcium chloride significantly reduced the early blight incidence and severity by increasing their concentrations. Their most effective concentration were 30 mg/ml that reduced the disease incidence by 50 and 62.4%, respectively. Superior effect of sodium bicarbonate or calcium chloride in disease reduction was observed when they combined with CBY. Field trails for evaluating the most promising greenhouse treatments were preformed under natural infestations during two successive summer seasons. Calcium chloride proved higher efficacy for reducing both disease incidence and severity than that of sodium bicarbonate when applied either alone or combined with CBY. Also, it is observed that increasing concentrations of both sodium bicarbonate or calcium chloride showed parallel decrease in disease incidence and severity. Application of (CBY) enhanced the efficacy of salts spraying against early blight disease. Similar trend was also observed with the increase of potato tubers yield. On the light of the present study it could be suggested that the usage of combined application of the yeastS. cerevisiaewith sodium bicarbonate or calcium chloride might be used as easily applied, safely and cost effective control methods against such plant diseases.

Photocatalytic removal of taste and odour compounds for drinking water treatment

Photocatalytic degradation of geosmin and 2-methylisoborneol (MIB), which are two taste and odour compounds commonly found in drinking water supply sources, was investigated using an immobilised TiO2 photoreactor. It was found that the degradation of geosmin and MIB followed similar pseudo-first-order kinetics with reaction rate constants being approximately 0.025 min−1 for typical geosmin and MIB concentrations of 250 and 500 ng/L. The normalised formal quantum efficiency was calculated to be in the range of 162–182 L/mol. Influence of additives (i.e. sodium bicarbonate and alcohols) on the degradation process was also investigated. It was found that there was a small reduction in the degradation rate constants of geosmin and MIB with increasing sodium bicarbonate concentration. At 50 mg/L sodium bicarbonate the degradation rate constants decreased by approximately 5%. Similarly, for methanol and ethanol concentrations up to 35 and 50 mg/L, respectively, these constants were found to also decrease. While addition of sodium bicarbonate and alcohols was seen to have relatively small negative effects on the photocatalytic degradation performance, the magnitude of their influence was consistent with the hypothesis that the degradation mechanism of geosmin and MIB was predominately that of attack involving HO∙ radicals.

Resposta em parâmetros sanguíneos e urinários de vacas leiteiras ao aumento no balanço cátion-aniônico da dieta

Estudou-se efeito de quatro níveis de dietas catiônicas sobre os parâmetros ácido-base do sangue e o pH urinário de vacas em lactação. Para a manipulação dos níveis do balanço cátion-amônico da dieta (BCAD), foram adicionadas diferentes concentrações de bicarbonato de sódio às dietas, obtendo-se os seguintes tratamentos: +150, +250, +400 e +500mEq/kg de matéria seca. O experimento foi realizado durante o verão, por um período total de 72 dias, utilizando-se oito vacas da raça Holandesa após o pico de lactação, distribuídas em quadrado latino (4x4), replicado, em que cada período teve duração de 18 dias. O pH urinário e o bicarbonato, o pH, o CO2 total e a pCO2 do sangue aumentaram linearmente (P&lt;0,01) com o aumento do BCAD. As concentrações de sódio e potássio do sangue não foram modificadas (P&gt;0,05) pelo BCAD. A concentração de cloro no sangue diminuiu linearmente (P&lt;0,01) com o aumento do BCAD. O aumento do BCAD afetou o equilíbrio ácido-base das vacas, promovendo efeito alcalinogênico, o que poderia levar a diferenças significativas no desempenho do animal.

Evaluation of effervescent floating matrix tablet formulations of salbutamol sulfate using full factorial design

The purpose of this research was to formulate and optimize an effervescent floating tablet formulation of salbutamol sulfate using full factorial design. Salbutamol sulfate has an absorption window in the stomach and in the upper part of the small intestine. A 32 full factorial design (eight runs) was utilized to optimize the formulation wherein the content of hydroxylpropyl methyl cellulose (HPMC) (X1) and sodium bicarbonate (X2) were taken as independent variables and % drug release after 6 h (Y1), t50% (Y2), and buoyancy lag time (BLT) (Y3) were taken as the dependent variables. Salbutamol sufate, HPMC K4M and HPMC K100M CR, stearic acid, talc, dicalcium phosphate, polyvinyl pyrrolidone, and magnesium stearate were used for the current research work. Two viscosity grades of HPMC as matrix materials were used for formulating the tablets, which were prepared by wet granulation. The release data were evaluated by the model-dependent (curve fitting) method using the PCP Disso v2.08 software. Optimization studies were carried out using the Design Expert Software (Version 7.0.3). The in vitro drug release mechanism showed anomalous transport. An increase in the concentration and viscosity grade of the polymer resulted in a decrease in the release rate, but it was found that at a higher concentration of HPMC, the viscosity grade did not significantly affect the drug release. Concentration of both HPMC and sodium bicarbonate had a significant effect on the BLT. Optimized effervescent floating tablets of salbutamol sulfate were successfully prepared and a good correlation was observed between predicted and actual values of the dependent variables chosen for the study. Viscosity grade of HPMC did not significantly impact the floatability of the dosage form. Thus, we can conclude that a combination of HPMC, stearic acid, and sodium bicarbonate can be used to increase the gastric residence time of the dosage form up to 12 h.

Factors Affecting the Synergy of Thiabendazole, Sodium Bicarbonate, and Heat To Control Postharvest Green Mold of Citrus Fruit

The efficacy of thiabendazole (TBZ) to control postharvest decay caused by Penicillium digitatum of citrus fruit can be enhanced by co-application with sodium bicarbonate (SBC) and/or heat treatment. The impact of these treatments was investigated in citrus fruit, as a function of TBZ and SBC concentration and temperature, and were related to the amount of TBZ residues in fruit (total residues), in fruit surface, in the cuticular wax, and in the inner fruit. The residue levels of TBZ were determined in 'Valencia' oranges following a 1 min dip in an aqueous mixture of SBC at 0.5, 1, or 2 wt %/vol and TBZ at 600 or 400 mg/L (active ingredient, a.i.) at 20 or 40 degrees C and after 0 and 20 days at 17 degrees C and 90% relative humidity. The influence of SBC and heat on the TBZ residue concentration on the fruit surface, in cuticular wax, and on the inner cuticle tissue was determined in 'Salustiana' oranges after a 1 or 3 min dip in TBZ alone at 600 mg/L and 20 or 50 degrees C or for 1 min in TBZ at 600 mg/L and SBC at 2% and 20 degrees C. The efficacy of heat treatments with water, SBC, and TBZ, applied separately or in combination, was investigated on artificially inoculated 'Nova' mandarins and 'Valencia' oranges for the control of postharvest green mold caused by a TBZ-sensitive (TBZ-s) or TBZ-resistant (TBZ-r) isolate of P. digitatum. The residue levels of TBZ in fruit, evaluated as total residues, were not affected by the co-application of SBC in most samples. While TBZ residues in the fruit surface were not significantly affected by the dip temperature or by co-application of SBC, the rates of diffusion and penetration of TBZ into cuticular wax markedly increased in the presence of SBC or when TBZ was applied in combination with heat. TBZ residues in the inner tissue of fruits treated at 20 degrees C were not dependent upon the dip time or by the presence of SBC and were similar to those found in fruit treated with TBZ at 50 degrees C for 1 min, whereas significantly higher values were recorded in samples treated with TBZ at 50 degrees C for 3 min. When TBZ at 600 mg/L and 20 degrees C was applied in the presence of SBC at concentrations of 1-2 or 0.5-2%, it effectively reduced decay caused by the TBZ-resistant isolate of green mold in 'Nova' mandarins and 'Valencia' oranges. This treatment was also significantly more effective than TBZ alone to control green mold caused by a TBZ-s isolate in 'Valencia' oranges. The combination with SBC and mild heat (40 degrees C) and TBZ at 400 mg/L generally improved the control of a TBZ-r isolate of green mold with respect to the combined treatment at 20 degrees C. TBZ efficacy was also improved when applied at reduced rates (200 mg/L) and 50 degrees C, significantly suppressing green mold caused by a TBZ-s isolate of P. digitatum and effectively controlling a TBZ-r isolate. The rate of weight loss of 'Valencia' oranges was significantly increased by SBC treatment and was positively dependent upon the concentration of SBC used in the treatment, while the temperature of the treatment solution had little influence on later weight loss.

The Influence of Biofilm on the Effectiveness of Ion Exchange Process

The ion exchange of ammonia in a synthetic zeolite has been investigated in the presence of Biofilm of nitrifying bacteria. The Biofilm has been cultivated on the zeolite carrier under different hydrodynamic conditions in a plug flow reactor and in a fluidized bed reactor. Samples of the carrier covered by Biofilm have been withdrawn from the reactors and packed into a miniature ion exchange column that has been used to analyze the ion exchange characteristics, i.e., to determine ion exchange equilibria and the mass transport kinetics. For this purpose, the breakthrough curves have been registered at different ammonia loadings and different concentrations of sodium bicarbonate in the solution. To analyze the mass transport mechanism and quantify kinetic coefficients, we have exploited a linear driving force model (i.e., the LDF model) and the generalized model. The ion exchange and mass transfer characteristics of the Biofilm-covered carrier have been compared to those of the virgin zeolite. The effect of Biofilm on the mass transfer kinetics and ion exchange capacity was found to be induced by swelling properties of zeolite.

Inositol hexaphosphate: a potential chelating agent for uranium

Chelation therapy is an optimal method to reduce the radionuclide-related risks. In the case of uranium incorporation, the treatment of choice is so far i.v infusion of a 1.4% sodium bicarbonate solution, but the efficacy has been proved to be not very high. In this study, we examine the efficacy of some substances: bicarbonate, citrate, diethylenetriamine pentaacetic acid (DTPA), ethidronate (EHBP) and inositol hexaphosphate (phytic acid) to chelate uranium using a test developed by Braun et al. Different concentrations of phytic acid, an abundant component of plant seeds that is widely distributed in animal cells and tissues in substantial levels, were tested and compared to the same concentrations of sodium citrate, bicarbonate, EHBP and DTPA. The results showed a strong affinity of inositol hexaphosphate for uranium, suggesting that it could be an effective chelating agent for uranium in vivo.

Intragastric pH probe functioning in studies of solutions with nonuniform pH

The goal of this work was to study the antimony electrode functioning in solution with nonuniform pH. Two research methods were developed. The first method was based on the use of the current-voltage curve of the pH probe. This method made it possible to study the dependence of the pH probe functioning on the contact patch size. The second method was based on experimental simulation of the pH probe contact with solutions with different pH. This method made it possible to study the dependence of the pH probe functioning on the gastric juice concentration. It was found that changes in sodium bicarbonate concentration had greater effect on the electrode functioning than changes in the gastric juice concentration.

Copper passivity and its breakdown in sodium bicarbonate solutions: A scanning electron microscopy and x-ray photoelectron and auger spectroscopy study

Effect of bicarbonate ions on the copper passivity and its local breakdown is studied by cyclic voltammetry, Auger spectroscopy, x-ray photoelectron spectroscopy, and scanning electron microscopy. Comparing data for solutions with various sodium bicarbonate concentrations shows copper to undergo pitting in 0.02 M NaHCO3, whereas it remains stably passive in 0.10 M NaHCO3. Independent studies suggest that carbonates play a protective role in stabilization of the oxide-hydroxide passive film on copper.

The effect of varying levels of sodium bicarbonate on polychlorinated biphenyl dechlorination in Hudson River sediment cultures

The addition of different concentrations of sodium bicarbonate had a profound effect on 2,3,4,5-chlorobiphenyl (2,3,4,5-CB) dechlorination in Hudson River sediment cultures. The most extensive dechlorination was observed in cultures to which 100 mg l(-1) bicarbonate was added. Cultures amended with 1000 mg l(-1) bicarbonate had the least extensive dechlorination, with 2,4-CB and 2,5-CB as predominant end-products. A significant loss of total chlorinated biphenyl mass was observed in cultures to which < or = 500 mg l(-1) bicarbonate was added, suggesting that degradation beyond chlorinated biphenyls occurred. The dynamics of acetate formation were different among the treatments, with high acetate concentrations detected throughout the 303-day experiment in cultures to which 1000 mg l(-1) bicarbonate had been added. Sodium bicarbonate addition also had a significant impact on bacterial community structure as detected by polymerase chain reaction-denaturant gradient gel electrophoresis (PCR-DGGE) of 16S rRNA gene fragments. Three putative polychlorinated biphenyl (PCB) dechlorinators were identified; one Dehalococcoides-like population was detected in all enrichment cultures, whereas two Dehalobacter-like populations were only detected in the enrichment cultures with the most extensive dechlorination. These results suggest that the availability of bicarbonate, and potentially sodium, may affect PCB dechlorination in Hudson River sediment and thus need to be taken into consideration when assessing the fate of PCBs or implementing bioremediation.

CO2 partial pressure pH relationships in the medium and relevance to CO2 mass balance in outdoor open thin-layer Arthrospira (Spirulina) cultures

A mathematical formula was derived for pCO 2 (partial pressure of dissolved carbon dioxide) in culture medium as a function of pH. The formula was verified in laboratory experiments with desorption of CO 2 from the mediuminto air which had been bubbled through a medium commonly used (ZARROUK'S recipe) for cultivation of the microalga Arthrospira (Spirulina). Concentration of sodium bicarbonate in the medium was 9 and 16.8 g l - 1 , respectively, at temperatures of 30 and 40 °C. The overall volumetric mass transfer coefficient K L a/V for CO 2 transfer from the medium into the gas phase increased about 2 % per 1°C increase of temperature and was not influenced by bicarbonate concentration in the medium. Mass balance of CO 2 in a suspension of Spirulina flowing in a layer of 8 mm thickness down an inclined cultivation surface was formulated and investigated theoretically, taking into account CO 2 consumption by the alga and CO 2 mass transfer from the suspension into the atmosphere. Calculations suggested that dissolved free (not chemically bound) carbon dioxide and concentration of bicarbonate ions in the suspension are practically in mutual chemical equilibrium. Mass flux of carbon dioxide from the suspension into the atmosphere is enhanced at increased suspension pH as a result of CO 2 formation from bicarbonate ions.

Bubble Formation through Reaction at Liquid-Liquid Interfaces

Slag foaming is an important phenomenon in steelmaking processes with both beneficial as well as negative effects. The present work is part of the wider project on the modelling of slag foaming, with special reference to dynamic conditions. Since bubble formation is the first step to foam formation, the present work was carried out in an attempt to simulate the bubble formation in slag/metal reactions in steelmaking processes by water-modelling experiments. The bubble formation due to the gas produced through chemical reaction at the interface between oleic acid and sodium bicarbonate solution was systematically monitored. The chemical reaction rate was varied by varying the concentration of sodium bicarbonate. The bubbles were observed to be generated in the heavier aqueous phase just below the water-oil interface. The bubbles penetrated the interface and escaped through the oil phase. The rate of the reaction was estimated from the volume of the gas that passed the water/oil interface. It was observed that the bubble formation and bubble growth mechanism were influenced by the reaction rate while the bubble size seemed to be unaffected by the reaction rate.

Effect of pH on viability of Entodinium caudatum, Entodinium exiguum, Epidinium caudatum, and Ophryoscolex purkynjei in vitro

Cultures of Entodinium caudatum, Entodinium exiguum, Epidinium caudatum, and Ophryoscolex purkynjei were grown and transferred in poorly buffered media prepared using different concentrations of sodium bicarbonate and a nitrogen gas phase. By transferring every 12 or 24 h, culture pH was gradually decreased until the protozoa disappeared. The cultures were transferred by placing half of the culture into an equal volume of fresh medium, resulting in pH fluctuations similar to those in the rumen, resulting from fermentation, eating, and saliva production. All four species appeared to maintain their concentrations around pH 5.8, but numbers decreased as pH values fell below 5.6. The four species were similar in that they all survived above pH 5.3. These results differ from previous reports in which Entodinium species appeared to be more tolerant to low pH than all other species of rumen ciliates. No adaptation to low pH was observed in Epidinium caudatum cultures after recovery from pH 5.4 medium containing only one or two viable cells.

Longevity of Granular Iron in Groundwater Treatment Processes: Corrosion Product Development

Permeable reactive barriers employing iron as a reactive surface have received extensive attention. A remaining issue, however, relates to their longevity. As an integral part of a long-term column study conducted to examine the influence of inorganic cosolutes on iron reactivity toward chlorinated solvents and nitroaromatic compounds, Master Builder iron grains were characterized via scanning and transmission electron microscopy, electron energy loss spectroscopy (EELS), micro-Raman spectroscopy, and X-ray diffraction. Prior to exposure to carbonate solutions, the iron grains were covered by a surface scale that consisted of fayalite (Fe2SiO4), wüstite (FeO), magnetite (Fe3O4), maghemite (gamma-Fe2O3), and graphite. After 1100 days of exposure to solutions containing carbonate, other inorganic solutes, and organic contaminants, the wüstite, fayalite, and graphite of the original scale partially dissolved, and magnetite and iron carbonate hydroxide (Fe3(OH)2.2CO3) precipitated on top of the scale. Raman results indicate the presence of green rust (e.g., [Fe4(2+)Fe2(3+)(OH)12]-[CO3 x 2H2O]) toward the column outlet after 308 days of operation, although this mineral phase disappears at longer operation times. Grains extracted from a column exposed to a high concentration (20 mM) of sodium bicarbonate were more extensively weathered than those from columns exposed to 2 mM sodium bicarbonate. An iron carbonate hydroxide layer up to 100 microm thick was observed. Even though EELS analysis of iron carbonate hydroxide indicates that this is a redox-active phase, the thickness of this layer is presumed responsible for the previously observed decline in the reactivity of this column relative to low-bicarbonate columns. A silica-containing feed resulted in reduced reactivity toward TCE. Grains from this column had a strong enrichment of silicon in the precipitates, although no distinct silica-containing mineral phases were identified. The substitution of 2 mM calcium carbonate for 2 mM sodium bicarbonate in the feed did not produce a measurable reactivity loss, asthe discrete calcium carbonate precipitates that formed in this system did not severely restrict access to the reactive surface.

In vitro Growth and Shoot Multiplication of Achras zapota in a Controlled Carbon Dioxide Environment

The culture vessels with multiplying shoots of Achras zapota L. on Schenk and Hildebrandt (SH) medium containing 8.88 &mu;M 6-benzylaminopurine (BAP) with or without sucrose were kept under varied CO2 concentrations ranging from 0.6 to 40.0 g m-3 using different concentrations of sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3), potassium bicarbonate (KHCO3), and potassium carbonate (K2CO3) in small acrylic chambers. Complete absence of carbon source caused death of shoots within 20 d. Under elevated concentrations of CO2 (10.0 and 40.0 g m-3) the shoots grew photoautotrophically on sucrose-free medium. The growth of cultures was better at 40.0 g (CO2) m-3 than on 3.0 % sucrose under ambient air of growth room. However, the best response was obtained at 10.0 g (CO2) m-3 and 3.0 % sucrose where maximum number of shoots, shoot length, fresh and dry mass, total number of leaves and leaf area was observed.

Effect of Temperature and Sanitizers on the Survival of Feline Calicivirus, Escherichia coli, and F-Specific Coliphage MS2 on Leafy Salad Vegetables

We conducted a series of experiments to compare the survival of Escherichia coli, feline calicivirus, and F-specific coliphage MS2 on lettuce and cabbage with and without disinfection. Inoculated produce was held at 4, 25, or 37°C for 21 days or was treated with different concentrations of sodium bicarbonate, chlorine bleach, peroxyacetic acid, or hydrogen peroxide. Survival was measured by the decimal reduction value (time to 90% reduction in titer) and the change in log titers of the test organisms. A stronger correlation of survival measures was observed between feline calicivirus and MS2 than between E. coli and either of the viral agents at 25 and 37°C. The maximum time to detection limit for MS2 at all temperatures was 9 days, whereas feline calicivirus was detected for a maximum of 14 days at 4°C. In contrast, E. coli was detectable for 21 days at 4 and 25°C and for 14 days at 37°C. Significant increases in E. coli titer occurred within the first 5 days, but virus titers decreased steadily throughout the experiments. E. coli was also highly susceptible to all disinfectants except 1% sodium bicarbonate and 50 ppm chlorine bleach, whereas the viruses were resistant to all four disinfectants.

Equivalency of culture media for human in vitro fertilization formulated to have the same pH under an atmosphere containing 5% or 6% carbon dioxide

Culture media for human in vitro fertilization and early embryonic development were modified to maintain similar pH values under an atmosphere containing 5% or 6% carbon dioxide by adjusting the concentration of sodium bicarbonate. Similar results were obtained with both media groups in a mouse embryo assay and in human in vitro parameters of fertilization and early development and clinical outcomes.

Stimulation of nicotine demethylation by NaHCO(3) treatment using greenhouse-grown burley tobacco.

Experiments were conducted in tobacco (Nicotiana tabacum L.) to investigate the effect of sodium bicarbonate (NaHCO(3)) on the conversion of nicotine to nornicotine, a secondary alkaloid that can form the tobacco-specific nitrosamine N-nitrosonornicotine (NNN). The results showed that, under optimum conditions, NaHCO(3) stimulated nicotine conversion in converter plants to the maximum level predetermined by the genetic background. The conversion level in NaHCO(3)-treated leaves was 2-3 times higher than that in control leaves. For young seedlings the optimum concentration of sodium bicarbonate was 0.8% aqueous solution, and for adult plants the optimum concentration was 1%. Lower concentrations resulted in partial stimulation, whereas higher concentration damaged leaf tissue and resulted in a lower conversion level. Studies with different temperatures (from 22 to 43 degrees C) showed that 37 degrees C was optimal. This temperature allowed the least amount of time, 2-3 days for mature leaves and 4-6 days for green leaves, for the major converters to reach >95% of nicotine conversion. An examination of leaves from different growth stages and stalk positions showed that the amount of time needed for conversion was longer for young leaves and shorter for mature leaves. Treatment of leaves with NaHCO(3) affords a rapid and convenient means of identifying and removing nornicotine converter plants during growth in the greenhouse or field.