Thermodynamic simulation of stepwise precipitation of NH_(4)VO_(3)and NaHCO_(3)from carbonating Na_(3)VO_(4)solution

Thermodynamic simulation was conducted to design a new process of stepwise precipitating NH_(4)VO_(3)and NaHCO_(3)from regulating the CO_(2)carbonation of Na_(3)VO_(4)solution.Firstly,a new V(V)speciation model for the aqueous solution containing vanadate and carbonate is established by using the Bromley-Zemaitis activity coefficient model.Subsequently,thermodynamic equilibrium calculations are conducted to clarify the behavior of vanadium,carbon,sodium,and impurity species in atmospheric or high-pressure carbonation.To ensure the purity and recovery of vanadium products,Na_(3)VO_(4)solution is initially carbonated to the pH of 9.3-9.4,followed by precipitating NH_(4)VO_(3)by adding(NH_(4))_(2)CO_(3).After vanadium precipitation,the solution is deeply carbonated to the final pH of 7.3-7.5 to precipitate NaHCO_(3),and the remaining solution is recycled to dissolve Na_(3)VO_(4)crystals.Finally,verification experiments demonstrate that 99.1%of vanadium and 91.4%of sodium in the solution are recovered in the form of NH_(4)VO_(3)and NaHCO_(3),respectively.

The photosynthetic oxygen evolution does not exclude the important role and contribution of bicarbonate photolysis

Photosynthesis is the most important biochemical reaction on Earth. It has co-evolved and developed with the Earth, driving the biogeochemical cycle of all elements on the planet and serving as the only chemical process in nature that can convert light energy into chemical energy. Some heavy oxygen isotopic(^(18)O) labeling experiments have"conclusively" demonstrated that the oxygen released by photosynthesis comes only from water and are written into textbooks. However, it is not difficult to find that bicarbonate has never been excluded from the direct substrate of photosynthesis from beginning to end during the history of photosynthesis research. No convincing mechanism can be used to explain photosynthetic oxygen evolution solely from water photolysis. The bicarbonate effect, the Dole effect, the thermodynamic convenience of bicarbonate photolysis, the crystal structure characteristics of photosystem Ⅱ, and the reinterpretation of heavy oxygen isotopic labeling(^(18)O)experiments all indicate that the photosynthetic oxygen evolution does not exclude the important role and contribution of bicarbonate photolysis. The recently proposed view that bicarbonate photolysis is the premise of water photolysis, bicarbonate photolysis and water photolysis work together with a 1:1(mol/mol) stoichiometric relationship, and the stoichiometric relationship between oxygen and carbon dioxide released during photosynthetic oxygen evolution is also 1:1, has excellent applicability and objectivity, which can logically and reasonably explain the precise coordination between light and dark reactions during photosynthesis, the bicarbonate effect, the Dole effect, the Kok cycle and the neutrality of water and carbon in nature.This is of great significance for constructing the bionic artificial photosynthetic reactors and scientifically answering the question of the source of elemental stoichiometric relationships in nature.

A cascade of in situ conversion of bicarbonate to CO_(2) and CO_(2) electroreduction in a flow cell with a Ni-N-S catalyst

Combination of CO_(2) capture using inorganic alkali with subsequently electrochemical conversion of the resultant HCO_(3)^(-)to high-value chemicals is a promising route of low cost and high efficiency.The electrochemical reduction of HCO_(3)^(-)is challenging due to the inaccessible of negatively charged molecular groups to the electrode surface.Herein,we adopt a comprehensive strategy to tackle this challenge,i.e.,cascade of in situ chemical conversion of HCO_(3)^(-)to CO_(2) and CO_(2) electrochemical reduction in a flow cell.With a tailored Ni-N-S single atom catalyst(SACs),where sulfur(S)atoms located in the second shell of Ni center,the CO_(2)electroreduction(CO_(2)ER)to CO is boosted.The experimental results and density functional theory(DFT)calculations reveal that the introduction of S increases the p electron density of N atoms near Ni atom,thereby stabilizing^(*)H over N and boosting the first proton coupled electron transfer process of CO_(2)ER,i.e.,^(*)+e^(-)+^(*)H+^(*)CO_(2)→^(*)COOH.As a result,the obtained catalyst exhibits a high faradaic efficiency(FE_(CO)~98%)and a low overpotential of 425 mV for CO production as well as a superior turnover frequency(TOF)of 47397 h^(-1),outcompeting most of the reported Ni SACs.More importantly,an extremely high FECOof 90%is achieved at 50 mA cm^(-2)in the designed membrane electrode assembly(MEA)cascade electrolyzer fed with liquid bicarbonate.This work not only highlights the significant role of the second coordination on the first coordination shell of the central metal for CO_(2)ER,but also provides an alternative and feasible strategy to realize the electrochemical conversion of HCO_(3)^(-)to high-value chemicals.

New method of local adjuvant therapy with bicarbonate Ringer’s solution for tumoral calcinosis: A case report

BACKGROUND Tumoral calcinosis is a condition characterized by deposits of calcium phosphate crystals in extra-articular soft tissues,occurring in hemodialysis patients.Calcium phosphate crystals are mainly composed of hydroxyapatite,which is highly infilt-rative to tissues,thus making complete resection difficult.An adjuvant method to remove or resolve the residual crystals during the operation is necessary.CASE SUMMARY A bicarbonate Ringer’s solution with bicarbonate ions(28 mEq/L)was used as the adjuvant.After resecting calcium phosphate deposits of tumoral calcinosis as much as possible,while filling with the solution,residual calcium phosphate deposits at the pseudocyst wall can be gently scraped by fingers or gauze in the operative field.A 49-year-old female undergoing hemodialysis for 15 years had swelling with calcium deposition for 2 years in the shoulders,bilateral hip joints,and the right foot.A shoulder lesion was resected,but the calcification remained and early re-deposition was observed.Considering the difficulty of a complete rection,we devised a bicarbonate dissolution method and excised the foot lesion.After resection of the calcified material,the residual calcified material was washed away with bicarbonate Ringer’s solution.CONCLUSION The bicarbonate dissolution method is a new,simple,and effective treatment for tumoral calcinosis in hemodialysis patients.

Mechanisms involved in Helicobacter pylori induced duodenal ulcer disease:an overview

Duodenal ulcer (DU) can be developed viaseveral different mechanisms.Hypersecretion ofgastric acid is,however,a common denominator.Amassive hypersecretion of acid can by itself evoke aDU,e.g.in the Zollinger-Ellison syndrome.Irrespective of the mechanism behind thedevelopment of a DU,powerful antisecretorytreatment will heal the ulcer and preventrecurrence.

经胸多普勒超声评价二尖瓣位Sorin Bicarbon双叶机械瓣功能

目的应用多个多普勒参数相结合的方法评价功能正常二尖瓣位Sorin Bicarbon双叶机械瓣。方法选择单独二尖瓣位Sorin Bicarbon双叶机械瓣置换患者56例,多普勒超声测量瓣口及左室流出道的血流速度、压差及速度时间积分;运用PHT和连续方程两种方法分别获得有效瓣口面积(EOA),并用体表面积进行校正(IEOA);计算机械瓣功能指数(PPI)。结果所有患者IEOACON显著小于IEOAPHT(P<0.01),E≤1.9 m/s及PHT<120 ms,83.93%患者TVIMVP/TVILVOT比值<2.2。四种型号机械瓣E及TVIMVP/TVILVOT比值差异无显著性意义,随着瓣膜型号的逐渐增大,PPI逐渐减小,但差别无统计学意义。结论E、PHT及TVIMVP/TVILVOT比值等多普勒参数相结合可较好地评价二尖瓣位Sorin Bicarbon双叶机械瓣功能。

Bicarbonate activation of hydrogen peroxide: A new emerging technology for wastewater treatment

The serious limitations of available technologies for decontamination of wastewater have compelled researchers to search for alternative solutions. Catalytic treatment with hydrogen peroxide, which appears to be one of the most efficient treatment systems, is able to degrade various organics with the help of powerful ·OH radicals. This review focuses on recent progress in the use of bicarbonate activated hydrogen peroxide for wastewater treatment. The introduction of bicarbonate to pollutant treatment has led to appreciable improvements, not only in process efficiency, but also in process stability. This review describes in detail the applications of this process in homogeneous and heterogeneous systems. The enhanced degradation, limited or lack of leaching during heterogeneous degradation, and prolonged catalysts stability during degradation are salient features of this system. This review provides readers with new knowledge regarding bicarbonate, including the fact that it does not always harm pollutant degradation, and can significantly benefit degradation under some conditions.

Passivation process of X80 pipeline steel in bicarbonate solutions

The passivation process of X80 pipeline steel in bicarbonate solutions was investigated using potentiodynamic, dynamic electro-chemical impedance spectroscopy （DEIS）, and Mott-Schottky measurements. The results show that the shape of polarization curves changes with concentration. The critical ＇passive＇ concentration is 0.009 mol/L for X80 pipeline steel in bicarbonate solutions. No anodic current peak exists in solutions when the concentration is lower than 0.009 mol/L, whereas there are one and two anodic current peaks when the concentration ranges from 0.009 to 0.05 mol/L and is higher than 0.1 mol/L, respectively. DEIS measurements show that there exist active dissolution range, transition range, pre-passive range, passive layer formation range, passive range, and trans-passive range for X80 pipeline steel in the 0.1 mol/L solutions. The results of DEIS measurements are in complete agreement with the potentiodynamic diagram. An equivalent circuit containing three sub-layers is used to explain the Nyquist plots in the passive range. Analyses are well made for explaining the corresponding fitted capacitance and impedance. The Mott-Schottky plots show that the passive film of X80 pipeline steel is an n-type semiconductor, and capacitance measurements are in good accordance with the results of DEIS experiment.

Cholangiocyte anion exchange and biliary bicarbonate excretion

Primary canalicular bile undergoes a process of fluidization and alkalinization along the biliary tract that is influenced by several factors including hormones, innervation/neuropeptides, and biliary constituents. The excretion of bicarbonate at both the canaliculi and the bile ducts is an important contributor to the generation of the so-called bile-salt independent flow. Bicarbonate is secreted from hepatocytes and cholangiocytes through parallel mechanisms which involve chloride efflux through activation of Cl- channels, and further bicarbonate secretion via AE2/SLC4A2-mediated Cl-/HCO3- exchange. Glucagon and secretin are two relevant hormones which seem to act very similarly in their target cells （hepatocytes for the former and cholangiocytes for the latter）. These hormones interact with their specific G protein-coupled receptors, causing increases in intracellular levels of cAMP and activation of cAMP-dependent Cl- and HCO3- secretory mechanisms. Both hepatocytes and cholangiocytes appear to have cAMP-responsive intracellular vesicles in which AE2/SLC4A2 colocalizes with cell specific Cl- channels （CFTR in cholangiocytes and not yet determined in hepatocytes） and aquaporins （AQP8 in hepatocytes and AQP1 in cholangiocytes）, cAMP-induced coordinated trafficking of these vesicles to either canalicular or cholangiocyte lumenal membranes and further exocytosis results in increased osmotic forces and passive movement of water with net bicarbonate-rich hydrocholeresis.

Stress corrosion cracking of X80 pipeline steel exposed to high pH solutions with different concentrations of bicarbonate

Susceptibilities to stress corrosion cracking （SCC） of X80 pipeline steel in high pH solutions with various concentrations of HC03 at a passive potential of-0.2 V vs. SCE were investigated by slow strain rate tensile （SSRT） test. The SCC mechanism and the effect of HC03 were discussed with the aid of electrochemical techniques. It is indicated that X80 steel shows enhunced susceptibility to SCC with the concentration of HCO3 increasing from 0.15 to 1.00 mol/L, and the susceptibility can be evaluated in terms of current density at -0.2 V vs. SCE. The SCC behavior is controlled by the dissolution-based mechanism in these circumstances. Increasing the concentration of HCO3 not only increases the risk of rupture of passive films but also promotes the anodic dissolution of crack tips. Besides, little susceptibility to SCC is found in dilute solution containing 0.05 mol/L HCO3 for X80 steel. This can be attributed to the inhibited repassivation of passive films, manifesting as a more intensive dissolution in the non-crack tip areas than at the crack tips.

Challenges and opportunities for using formate to store, transport, and use hydrogen

In this perspective article,the synthesis and thermodynamic properties of aqueous solutions of formate salts(FS,HCO2-)are described in relationship to the concept of H2carriers.The physiochemical properties of solid FS,aqueous formate solutions,and aqueous bicarbonate solutions set the limitations for storage capacity,deliverable capacity,and usable H2capacity of these H2carriers,respectively.These parameters will help in the design of systems that use H2carriers for storage and transport of H2for fuel cell power applications.FS,as well as admixtures with formic acid(FA,H2CO2),have potential to address the goals outlined in the U.S.Department of Energy’s H2@scale initiative to store in chemical bonds a significant quantity of energy(hundreds of megawatts)obtained from large scale renewable resources.

Effects of nuclei ambiguus and dorsal motor nuclei of vagus on gastric H^+ and HCO_3^- secretion in rats

AIM: To determine the effects of electrical stimulation of nucleus ambiguus (NA) and dorsal motor nuclei of vagus (DMV) on gastric acid and bicarbonate secretion in rats. METHODS: NA and DMV in rats were electrically stimulated. Pylorus ligation or esophagus perfusion was used to collect the gastric secretion. The titratable H+ quantum, H+ concentration, HCO3- secretion quantum were measured. RESULTS: Electrical stimulation of NA had no effects on the volume of gastric juice, titratable acidity and acid concentration, but elicited a pronounced increase in the total bicarbonate. However, electrical stimulation of DMV significantly increased the titratable acidity, the volume of gastric juice and the acid concentration. Similarly, electrical stimulation of either NA or DMV decreased the respiratory frequency and sinus bradycardia. CONCLUSION: NA in rats can not control the secretion of gastric acid but the secretion of bicarbonate in gastric juice, while DMV controls the secretion of gastric acid.

Quantification of photosynthetic inorganic carbon utilisation via a bidirectional stable carbon isotope tracer

The amount of bicarbonate utilised by plants is usually ignored because of limited measurement methods. Accordingly, this study quantified the photosynthetic assimilation of inorganic carbon （COe and HCO3-） by plants. The net photosynthetic COa assimilation （PN）, the photosynthetic assimilation of CO2 and bicarbonate （PN＇）, the proportion of increased leaf area （lEA） and the stable carbon isotope composition （δ13C） of Orychophragmus violaceus （Ov） and Brassica juncea （B j） under three bicarbonate levels （5, 10 and 15 mm NaHCO3） were examined to determine the relationship among PN, PN＇ and fLA. PN＇, not PN, changed synchronously with fLA. Moreover, the proportions of exogenous bicarbonate and total bicarbonate （including exogenous bicarbonate and dissolved CO2-generated bicarbonate） utilised by Ov were 2.27 % and 5.28 % at 5 mm bicarbonate, 7.06 % and 13.28 % at 10 mm bicarbonate, and 8.55 % and 17.31% at 15 mm bicarbonate, respectively. Meanwhile, the propor- tions of exogenous bicarbonate and total bicarbonate uti- lised by Bj were 1.77 % and 3.28 % at 5 mm bicarbonate, 2.11% and 3.10 % at 10 mm bicarbonate, and 2.36 % and 3.09 % at 15 mm bicarbonate, respectively. Therefore, the dissolved CO2-generated bicarbonate and exogenous bicarbonate are important sources of inorganic carbon for plants.

Effect of HCO_3^- concentration on CO_2 corrosion in oil and gas fields

The effect of HCO3^- concentration on CO2 corrosion was investigated by polarization measurement of potentiodynamic scans and weight-loss method, Under the conditions of high pressure and high temperature, the corrosion rate of steel X65 decreased with the increase of HCO3^- concentration, while pH of solution increased. SEM, EDS, and XRD results of the corrosion scales indir cated that the typical FeCO3 crystallite was found at low HCO3^- concentration but Ca（Fe,Mg）（CO3）2 was found at high HCO3^- con- centration. Ca^2＋ and Mg^2＋ are precipitated preferential to Fe^2＋ at high pH value. Potentiodynamic polarization curves showed that the cathodic current density decreases with the increase of HCO3^- concentration at low HCO3^- concentration. When the HCO3^- concentration reaches 0.126 mol/L, increasing HCO3^- concentration promotes cathodic reactions. Anodic behavior is an active process at low HCO3^- concentration and the anodic current density decreases with the increase of HCO3^- concentration. An evident active-passive behavior is exhibited in anodic process at 0.126 mol/L HCO3^-.

Cyclic metallurgical process for extracting Ⅴ and Cr from vanadium slag: Part Ⅰ. Separation and recovery of Ⅴ from chromium-containing vanadate solution

The separation and recovery of V from chromium-containing vanadate solution were investigated by a cyclic metallurgical process including selective precipitation of vanadium,vanadium leaching and preparation of vanadium pentoxide.By adding Ca(OH)_(2) and ball milling,not only the V in the solution can be selectively precipitated,but also the leaching kinetics of the precipitate is significantly improved.The precipitation efficiency of V is 99.59%by adding Ca(OH)_(2) according to Ca/V molar ratio of 1.75:1 into chromium-containing vanadate solution and ball milling for 60 min at room temperature,while the content of Cr in the precipitate is 0.04%.The leaching rate of V reaches 99.35%by adding NaHCO_(3) into water according to NaHCO_(3)/V molar ratio of 2.74:1 to leach V from the precipitate with L/S ratio of 4:1 mL/g and stirring for 60 min at room temperature.The crystals of NH_(4)VO_(3) are obtained by adjusting the leaching solution pH to be 8.0 with CO2 and then adding NH_(4)HCO_(3) according to NH_(4)HCO_(3)/NaVO_(3) molar ratio of 1:1 and stirring for 8 h at room temperature.After filtration,the crystallized solution containing ammonia is reused to leach the precipitate of calcium vanadates,and the leaching efficiency of V is>99%after stirring for 1 h at room temperature.Finally,the product of V_(2)O_(5) with purity of 99.6%is obtained by calcining the crystals at 560℃ for 2 h.

Preparation of Fine Spherical Particle Sized Ceria by Precipitation Method with Ammonium Bicarbonate

Fine spherical particle sized ceria (CeO_2) was prepared by homogeneous precipitation method with ammonium bicarbonate as precipitant. The prepared CeO_2 has the primary particle size of 10～50 nm when calcined between 400～700 ℃ analyzed by XRD and the aggregated particle size is about 300 nm measured by LASER particle sizer. SEM, TG-DTA and Zeta-potential analyzer were employed individually to study the morphology and the formation of CeO_2 product. It was found that excess NH_4NO_3 can serve as an sphericallization agent to prepare spherical CeO_2 powder by precipitation method.

Effect of Zn deficiency and excessive bicarbonate on the allocation and exudation of organic acids in two Moraceae plants

The effect of zinc(Zn) deficiency and excessive bicarbonate on the allocation and exudation of organic acids in plant organs(root, stem, and leaf) and root exudates of two Moraceae plants(Broussonetia papyrifera and Morus alba) were investigated. Two Moraceae plants were hydroponically grown and cultured in nutrient solution in four different treatments with 0.02 mM Zn or no Zn,combined with no or 10 mM bicarbonate. The variations of organic acids in different plant organs were similar to those of root exudates in the four treatments except B. papyrifera, which was in a treatment that was a combination of 0.02 mM Zn and no bicarbonate. The response characteristics in the production, translocation, and allocation of organic acids in the plant organs and root exudates varied with species and treatments. Organic acids in plant organs and root exudates increased under Zn-deficient conditions,excessive bicarbonate, or both. An increase of organic acids in the leaves resulted in an increase of root-exuded organic acids. B. papyrifera translocated more oxalate and citrate from the roots to the rhizosphere than M. alba under the dual influence of 10 mM bicarbonate and Zn deficiency. Organic acids of leaves may be derived from dark respiration and photorespiration. By comparison, organic acids in stems, roots, and root exudates may be derived from dark respiration and organic acid translocation from the leaves. These results provide evidence for the selective adaptation of plants to environments with low Zn levels or high bicarbonate levels such as a karst ecosystem.

Effect of Electrochemical Treatment in Aqueous Ammonium Bicarbonate on Surface Properties of PAN-based Carbon Fibers

The surface properties of PAN-based carbon fibers electrochemically treated in aqueous ammonium bicarbonate before and after treatment were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Dynamic Contact Angle Analysis (DCAA). The results of characterization indicated that the oxygen and nitrogen contents in carbon fiber surface were significantly increased by electrochemical treatment, and amide groups was introduced onto it, which was related with the electrolyte. The AFM photographs illustrated that the roughness of the fiber surface was also increased. The wettibality of the fibers was improved after treatment because the surface energy especially the polar part of it was increased.

Use of sodium bicarbonate and blood gas monitoring in diabetic ketoacidosis: A review

Diabetic ketoacidosis(DKA) is a severe and toocommon complication of uncontrolled diabetes mellitus. Acidosis is one of the fundamental disruptions stemming from the disease process, the complications of which are potentially lethal. Hydration and insulin administration have been the cornerstones of DKA therapy; however, adjunctive treatments such as the use of sodium bicarbonate and protocols that include serial monitoring with blood gas analysis have been much more controversial. There is substantial literature available regarding the use of exogenous sodium bicarbonate in mild to moderately severe acidosis; the bulk of the data argue against significant benefit in important clinical outcomes and suggest possible adverse effects with the use of bicarbonate. However, there is scant data to support or refute the role of bicarbonate therapy in very severe acidosis. Arterial blood gas(ABG) assessment is an element of some treatment protocols, including society guidelines, for DKA. We review the evidence supporting these recommendations. In addition, we review the data supporting some less cumbersome tests, including venous blood gas assessment and routine chemistries. It remains unclear that measurement of blood gas pH, via arterial or venous sampling, impacts management of the patient substantially enough to warrant the testing, especially if sodium bicarbonate administration is not being considered. There are special circumstances when serial ABG monitoring and/or sodium bicarbonate infusion are necessary, which we also review. Additional studies are needed to determine the utility of these interventions in patients with severe DKA and pH less than 7.0.