scholarly journals Distribution Diagrams and Graphical Methods to Determine or to Use the Stoichiometric Coefficients of Acid-Base and Complexation Reactions

10.5772/34640 ◽  
2012 ◽  
Author(s):  
Alberto Rojas-Hernndez ◽  
Norma Rodrguez-Laguna ◽  
Mara Teresa ◽  
Rosario Moya-Hernndez
Keyword(s):  
Graphical Methods ◽  
Acid Base ◽  
Complexation Reactions

A combined kinetic and computational study of the reactions of transient germylenes with oxiranes and thiiranes in solution

2015 ◽  
Vol 93 (4) ◽  
pp. 435-444 ◽  
Author(s):  
Svetlana S. Kostina ◽  
William J. Leigh
Keyword(s):  
Steady State ◽  
Lewis Acid ◽  
Density Functional ◽  
Computational Study ◽  
Equilibrium Constants ◽  
Density Functional Theory Calculations ◽  
Laser Flash ◽  
Acid Base ◽  
Hydrocarbon Solvents ◽  
Complexation Reactions

The reactions of dimethyl- and diphenylgermylene (GeMe2 and GePh2, respectively) with cyclohexene oxide (CHO) and propylene sulfide (PrS) have been studied in hydrocarbon solvents at 25 °C by laser flash and steady-state photolysis methods using appropriately substituted germacyclopent-3-ene derivatives as germylene precursors. GeMe2 reacts with CHO and PrS with rate constants in the range of 1.2–1.7 × 1010 M−1 s−1 in hexanes at 25 °C to form new transient products that are assigned to the corresponding Lewis acid-base complexes of the germylene with the substrates. The complexation reactions were found to be reversible and are characterized by equilibrium constants of KC = (3.7 ± 0.8) × 103 M−1 and (3 ± 1) × 104 M−1 for complexation of GeMe2 with CHO and PrS, respectively. The complexes decay over approximately 10 μs with the concomitant formation of tetramethyldigermene (Ge2Me4), identifiable by its characteristic UV-vis spectrum centered at λmax = 370 nm. Diphenylgermylene behaves analogously, reacting rapidly and reversibly with the two substrates to form the corresponding Lewis acid-base complexes (λmax ≈ 355 nm) that decay over several tens of microseconds with the concomitant growth of the characteristic UV-vis spectrum of tetraphenyldigermene (Ge2Ph4) (λmax = 440 nm). Steady-state photolysis of the germylene precursors in the presence of CHO afforded germanium-containing oligomers but showed no evidence of oxygen abstraction or the formation of substrate-derived product(s). Similar photolyses in the presence of PrS also afforded germanium-containing oligomers, but as well yielded propene in 20%–30% yield and (in the case of the GePh2 precursor) minor amounts of low molecular weight compounds that appear to be derived from the corresponding germanethione. Density functional theory calculations of the chalcogen abstraction reactions of GeMe2 with oxirane and thiirane in the gas phase have been carried out at the B3LYP/6-311+G(d,p) level of theory and are in good qualitative agreement with the experimental data.

Higher Dietary Acidity is Associated with Lower Bone Mineral Density in Postmenopausal Iranian Women, Independent of Dietary Calcium Intake

2014 ◽  
Vol 84 (3-4) ◽  
pp. 0206-0217 ◽  
Author(s):  
Seyedeh-Elaheh Shariati-Bafghi ◽  
Elaheh Nosrat-Mirshekarlou ◽  
Mohsen Karamati ◽  
Bahram Rashidkhani
Keyword(s):  
Calcium Intake ◽  
Dietary Calcium ◽  
Dietary Calcium Intake ◽  
Dietary Intakes ◽  
Iranian Women ◽  
Acid Base Balance ◽  
Mineral Density ◽  
Acid Base ◽  
Base Balance ◽  
Dietary Acid

Findings of studies on the link between dietary acid-base balance and bone mass are relatively mixed. We examined the association between dietary acid-base balance and bone mineral density (BMD) in a sample of Iranian women, hypothesizing that a higher dietary acidity would be inversely associated with BMD, even when dietary calcium intake is adequate. In this cross-sectional study, lumbar spine and femoral neck BMDs of 151 postmenopausal women aged 50 - 85 years were measured using dual-energy x-ray absorptiometry. Dietary intakes were assessed using a validated food frequency questionnaire. Renal net acid excretion (RNAE), an estimate of acid-base balance, was then calculated indirectly from the diet using the formulae of Remer (based on dietary intakes of protein, phosphorus, potassium, and magnesium; RNAERemer) and Frassetto (based on dietary intakes of protein and potassium; RNAEFrassetto), and was energy adjusted by the residual method. After adjusting for potential confounders, multivariable adjusted means of the lumbar spine BMD of women in the highest tertiles of RNAERemer and RNAEFrassetto were significantly lower than those in the lowest tertiles (for RNAERemer: mean difference -0.084 g/cm2; P=0.007 and for RNAEFrassetto: mean difference - 0.088 g/cm2; P=0.004). Similar results were observed in a subgroup analysis of subjects with dietary calcium intake of >800 mg/day. In conclusion, a higher RNAE (i. e. more dietary acidity), which is associated with greater intake of acid-generating foods and lower intake of alkali-generating foods, may be involved in deteriorating the bone health of postmenopausal Iranian women, even in the context of adequate dietary calcium intake.

To Manage Infantile Hypertrophic Pyloric Stenosis by "Double-Y Pyloromyotomy" is a better Surgical Approach

2014 ◽  
Vol 1 (2) ◽  
pp. 143-147
Author(s):  
Md. Ansar Ali ◽  
Kaniz Hasina ◽  
Shahnoor Islam ◽  
Md. Ashraf Ul Huq ◽  
Md. Mahbub-Ul Alam ◽  
...  
Keyword(s):  
Weight Gain ◽  
Pyloric Stenosis ◽  
Hypertrophic Pyloric Stenosis ◽  
Treatment Modalities ◽  
Infantile Hypertrophic Pyloric Stenosis ◽  
Postoperative Vomiting ◽  
Acid Base ◽  
Feeding Regimes ◽  
Acid Base Status ◽  
Postoperative Feeding

Background: Different treatment modalities and procedures have been tried for the management of infantile hypertrophic pyloric stenosis. But surgery remains the mainstay for management of IHPS. Ramstedt’s pyloromyotomy was described almost over a hundred years ago and to date remains the surgical technique of choice. An alternative and better technique is the double-Y pyloromyotomy, which offer better results for management of this common condition.Methods: A prospective comparative interventional study of 40 patients with IHPS was carried out over a period of 2 years from July 2008 to July 2010. The patients were divided into 2 equal groups of 20 patients in each. The study was designed that all patients selected for study were optimized preoperatively regarding to hydration, acid-base status and electrolytes imbalance. All surgeries were performed after obtaining informed consent. Standard preoperative preparation and postoperative feeding regimes were used. The patients were operated on an alternate basis, i.e., one patient by Double-Y Pyloromyotomy(DY) and the next by aRamstedt’s Pyloromyotomy (RP). Data on patient demographics, operative time, anesthesia complications, postoperative complications including vomiting and weight gain were collected. Patients were followed up for a period of 3 months postoperatively. Statistical assessments were done by using t test.Results: From July 2008 through July 2010, fourty patients were finally analyzed for this study. Any statistical differences were observed in patient population regarding age, sex, weight at presentation, symptoms and clinical condition including electrolytes imbalance and acid-base status were recorded. Significant differences were found in postoperative vomiting and weight gain. Data of post operative vomiting and weight gain in both groups were collected. Vomiting in double-Y(DY) pyloromyotomy group (1.21 ± 0.45days) vs Ramstedt’s pyloromyotomy (RP) group(3.03 ± 0.37days) p= 0.0001.Weight gain after 1st 10 days DY vs RP is ( 298 ± 57.94 gm vs193±19.8 gm p=0.0014), after 1 month (676.67±149.84 gm vs 466.67 ± 127.71 gm, p=0.0001), after 2months (741.33± 278.74 gm vs 490±80.62 gm, p=0.002) and after 3 months (582±36.01gm vs 453.33±51.64 gm, p=0.0001).No long-term complications were reported and no re-do yloromyotomy was needed.Conclusion: The double-Y pyloromyotomy seems to be a better technique for the surgical management of IHPS. It may offer a better functional outcome in term of postoperative vomiting and weight gain.DOI: http://dx.doi.org/10.3329/jpsb.v1i2.19532

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