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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new efficient, simple and versatile algorithm is presented for determination of the protolytic constants from spectrophotmetric data in multiwavelength mode based on the combining of hard and soft modeling. The algorithm was checked by determining the acidity constants of a triprotic acid from theoretical and real absorption-pH data. The real spectral data are obtained from photometric titration of different solutions of 4-(2-pyridylazo)resorcinol (PAR) by a standard base solution under an inert atmosphere. The algorithm starts the minimization process using an user supplied number of components and initial guesses of the unknown parameters and refined in a least squares manner. New algorithm is implemented in the new version of DATAN package (version 3.1). The validity of the obtained results was checked by some well known programs such as DATAN 2.1, SPECFIT/32, SQUAD, a modified version of difference spectra and a A-pH curve method. The comparison of the outputs of the DATAN 3.1 with the other programs reveals that there is a very good agreement between the obtained results and mentioned programs.
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PMID:A new algorithm for the determination of protolytic constants from spectrophotometric data in multiwavelength mode: Calculations of acidity constants of 4-(2-pyridylazo)resorcinol (PAR) in mixed nonaqueous-water solvents. 1897 Apr 51

The Sancho reservoir is an acid mine drainage (AMD)-contaminated reservoir located in the Huelva province (SW Spain) with a pH close to 3.5. The water is only used for a refrigeration system of a paper mill. The Sancho reservoir is holomictic with one mixing period per year in the winter. During this mixing period, oxygenated water reaches the sediment, while under stratified conditions (the rest of the year) hypoxic conditions develop at the hypolimnion. A CE-QUAL-W2 model was calibrated for the Sancho Reservoir to predict the thermocline and oxycline formation, as well as the salinity, ammonium, nitrate, phosphorous, algal, chlorophyll-a, and iron concentrations. The version 3.7 of the model does not allow simulating the oxidation of Fe(II) in the water column, which limits the oxygen consumption of the organic matter oxidation. However, to evaluate the impact of Fe(II) oxidation on the oxycline formation, Fe(II) has been introduced into the model based on its relationship with labile dissolved organic matter (LDOM). The results show that Fe oxidation is the main factor responsible for the oxygen depletion in the hypolimnion of the Sancho Reservoir. The limiting factors for green algal growth have also been studied. The model predicted that ammonium, nitrate, and phosphate were not limiting factors for green algal growth. Light appeared to be one of the limiting factors for algal growth, while chlorophyll-a and dissolved oxygen concentrations could not be fully described. We hypothesize that dissolved CO2 is one of the limiting nutrients due to losses by the high acidity of the water column. The sensitivity tests carried out support this hypothesis. Two different remediation scenarios have been tested with the calibrated model: 1) an AMD passive treatment plant installed at the river, which removes completely Fe, and 2) different depth water extractions. If no Fe was introduced into the reservoir, water quality would significantly improve in only two years. Deeper extractions (3m above the bottom) would also improve the water quality by decreasing the hypoxic zone. However, extractions at the epilimnion would increase the amount of hypoxic water in the reservoir.
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PMID:Oxycline formation induced by Fe(II) oxidation in a water reservoir affected by acid mine drainage modeled using a 2D hydrodynamic and water quality model - CE-QUAL-W2. 2709 16

A study was performed on the mandibular gland obtained from growing pigs enrolled in a wide research project aiming to test the effects of different feed physical forms on animal health, production and welfare. We used 48 pigs fed for four weeks with different dietary treatments based on different grinding intensities and compactions of the same diet, namely coarsely ground meal (CM), finely ground pelleted (FP) and coarsely ground pelleted (CP) diets. Samples were analyzed by conventional histochemistry to identify the glycohistochemical profile and by immunohistochemistry to localize aquaporin 5, apelin and apelin receptor. Statistical elaborations were performed using the Stats R-package, version 3.5.3. Pig mandibular gland adenomere increased both the quantity and acidity of produced glycoconjugates from CM to FP and CP diets. This probably calls forth higher watery saliva, thus promoting a better feed softening facilitating the amalgamation of the bolus. Mandibular gland increased aquaporin 5 positivity in the CP diet, supporting the hypothesis of an augmented demand for water. Based on apelin/receptor localization, it was hypothesized that in pig mandibular gland the apelinergic system likely performs an endocrine control on the demilunes activity and a paracrine control on ducts, facilitating the production of a more fluid saliva.
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PMID:Influence of Different Feed Physical Forms on Mandibular Gland in Growing Pigs. 3245 63