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Oxalate
Kinds of Oxalate Terms modified by Oxalate Selected AbstractsInorganic sulphate extraction from SO2 -impacted AndosolsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2005T. Delfosse Summary Sulphate sorption on to the surface of short-range ordered minerals and precipitation of Al-hydroxy sulphate contribute to the acid neutralizing capacity of soils. The correct measurement of total inorganic sulphate is thus essential in soils that are accumulating SO42, anions. We extracted SO42, by various solutions, namely 0.005 m Ca(NO3)2, 0.016 m KH2PO4, 0.5 m NH4F and 0.2 m acidic NH4 -oxalate (pH 3), from Vitric and Eutric Andosols exposed to prolonged deposition of acid and SO2 from an active volcano (Masaya, Nicaragua). We attributed sulphate extractable by KH2PO4 (20,3030 mg kg,1) to anion-exchangeable SO42,, which was much smaller than NH4F- and oxalate-extractable SO42, (400,9680 and 410,10 480 mg kg,1, respectively). Our results suggest the occurrence of a sparingly soluble Al-hydroxy-mineral phase extractable by both NH4F and oxalate. The formation of Al-hydroxy minerals would result from the combination of enhanced weathering caused by strong acid loading and simultaneous occurrence of large SO42, concentrations in soil solution. Oxalate extracted slightly more inorganic SO42, than did NH4F, this additional amount of SO42, correlating strongly with oxalate-extractable Si and Fe contents. Preferential occlusion of SO42, by short-range ordered minerals, especially ferrihydrite, explains this behaviour. If we exclude the contribution of occluded sulphate then oxalate and NH4F mobilize similar amounts of SO42, and are believed to mobilize all of the inorganic SO42, pool. [source] Effect of application form of nitrogen on oxalate accumulation and mineral uptake by napiergrass (Pennisetum purpureum)GRASSLAND SCIENCE, Issue 3 2010Mohammad Mijanur Rahman Abstract Oxalate occurs naturally in forage species, but excess levels of soluble oxalate adversely affect their nutritional quality as animal feed. Although induction of oxalate in plants has been associated with nitrate application, relatively little is known about oxalate in forage grasses. In the present study, we investigated oxalate accumulation and mineral uptake by napiergrass (Pennisetum purpureum, cv. dwarf-late) cultured in complete nutrient solution containing either solely nitrate or mainly ammonium as the main form of nitrogen. Total (shoot and root) yield of plants did not differ significantly between the nitrate and ammonium treatments. By contrast, the nitrogen form significantly affected oxalate accumulation and mineral uptake by plants. Nitrate application resulted in higher concentrations of soluble and insoluble oxalates in the shoot and soluble oxalate in the root than ammonium application. Nitrate application also resulted in higher concentrations of sodium and calcium in the shoot, and higher concentrations of sodium, calcium and magnesium in the root than ammonium application. The results suggest that the application of nitrate fertilizer as the sole source of nitrogen should be avoided in the cultivation of oxalate-rich forages, though further studies are needed under field conditions. [source] Structure of Staphylococcus aureus adenylosuccinate lyase (PurB) and assessment of its potential as a target for structure-based inhibitor discoveryACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2010Paul K. Fyfe The medium-resolution structure of adenylosuccinate lyase (PurB) from the bacterial pathogen Staphylococcus aureus in complex with AMP is presented. Oxalate, which is likely to be an artifact of crystallization, has been modelled in the active site and occupies a position close to that where succinate is observed in orthologous structures. PurB catalyzes reactions that support the provision of purines and the control of AMP/fumarate levels. As such, the enzyme is predicted to be essential for the survival of S. aureus and to be a potential therapeutic target. Comparisons of this pathogen PurB with the enzyme from Escherichia coli are presented to allow discussion concerning the enzyme mechanism. Comparisons with human PurB suggest that the close similarity of the active sites would make it difficult to identify species-specific inhibitors for this enyme. However, there are differences in the way that the subunits are assembled into dimers. The distinct subunit,subunit interfaces may provide a potential area to target by exploiting the observation that creation of the enzyme active site is dependent on oligomerization. [source] Formation of 2,6-Dioxabicyclo[3.3.0]-octa-3,7-dienes or Multiply Substituted o-Benzoquinones from Reactions of 1,4-Dilithio-1,3-dienes with Dimethyl Oxalate.CHEMINFORM, Issue 5 2005Guoliang Mao Abstract For Abstract see ChemInform Abstract in Full Text. [source] Hierarchical Structures in Tin(II) OxalatesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2008Padmini Ramaswamy Abstract Six new SnII oxalates exhibiting a hierarchy of structures have been prepared employing hydrothermal methods. The compounds I [C10N2H10][Sn(C2O4)2], II [C10N2H10][Sn2(C2O4)3], and III [C8N4H26][Sn(C2O4)2]2·2H2O possess zero-dimensional molecular structures; IV [C10N2H8]2[Sn(C2O4)]2 and V [C12N2H8][SnC2O4] have one-dimensional chain structures; and compound VI [C5N2H14]2[Sn4(C2O4)6]·7H2O has a two-dimensional layer structure. The SnII ions have 4- and 6-coordination with square-pyramidal or pentagonal-bipyramidal geometry, in which the lone pair of electrons also occupies one of the vertices. Weak intermolecular forces such as hydrogen-bond interactions, ,···, interactions, and lone-pair,, interactions have been observed and appear to lendstructural stability. Theoretical studies indicate that the ,···, interaction energy between the bound 1,10-phenanthroline molecules is of the order of 5,6 kcal,mol,1 in V. Natural bond orbital (NBO) analysis on two model compounds, II and IV, indicates reasonable lone-pair,, interactions. The close structural relationship between all the compounds indicates that a building-up process from the zero-dimensional monomer can be considered. The present structures provide opportunities for evaluating the structure-directing role of the lone pair of electrons of SnII.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Inorganic,Organic Hybrid Structures: Open-Framework Iron Phosphite,Oxalates of Varying DimensionalityCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2007Sukhendu Mandal Abstract Inorganic,organic hybrid structures belonging to the family of iron phosphite,oxalates have been prepared by employing hydrothermal methods. Their structures, determined by single-crystal X-ray diffraction, show a hierarchy within the family. While compounds I and II are low dimensional, III,VI have three-dimensional structures. Compound I has edge-shared ladders of iron phosphite with oxalate units hanging from the iron centers. Compound II has a layer structure with a honeycomb-like arrangement. The three-dimensional hybrid structures have the oxalate units connected in both in-plane and out-of-plane modes. A newly identified secondary building unit (SBU-7) and the oxalate units satisfying the valence and coordination requirements in the structure of V are novel and noteworthy structural features. Magnetic studies show that the dominant interactions between the iron centers are antiferromagnetic. Similar to other known hybrid structures, the phosphite,oxalate structures appear to show wide compositional and structural diversity. [source] Crystal growth and magnetic properties of the copper coordination polymer [Cu(µ -C2O4)(4-aminopyridine)2(H2O)]nCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2007A. V. Prokofiev Abstract In this paper, we consider various ways of crystal growth of the polymer [Cu(µ -C2O4)(4-aminopyridine)2(H2O)]n. Single crystals of the size of 1.5×1.5×0.2 mm3 have been grown by a slow diffusion technique from solutions of the monoammine copper complex and of the mixture of potassium oxalate and aminopyridine with the stoichiometric ratio. Magnetic susceptibility and ESR measurements have been performed on single crystals large enough for investigating anisotropic properties. The susceptibility can be well described within the model of a Heisenberg antiferromagnetic spin chain. The magnetic measurements reveal a small concentration of paramagnetic moments reflecting the high quality of the single crystals. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A study of primary nucleation of calcium oxalate monohydrate: II.CRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2004Effect of urinary species Abstract Kidney stones consist of various organic and inorganic compounds. Calcium oxalate monohydrate (COM) is the main inorganic constituent of kidney stones. However, the mechanisms for the formation of calcium oxalate kidney stones are not well understood. In this regard, there are several hypotheses including nucleation, crystal growth and/or aggregation of formed COM crystals. The effect of some urinary species such as oxalate, calcium, citrate, and protein on nucleation and crystallization characteristics of COM is determined by measuring the weight of formed crystals and their size distributions under different chemical conditions, which simulate the urinary environment. Statistical experimental designs are used to determine the interaction effects among various factors. The data clearly show that oxalate and calcium promote nucleation and crystallization of COM. This is attributed to formation of a thermodynamically stable calcium oxalate monohydrate resulting from supersaturation. Citrate, however, inhibits nucleation and further crystal growth. These results are explained on the basis of the high affinity of citrate to combine with calcium to form soluble calcium citrate complexes. Thus, citrate competes with oxalate ion for binding to calcium cations. These conditions decrease the amount of free calcium ions available to form calcium oxalate crystals. In case of protein (mucin), however, the results suggest that no significant effect could be measured of mucin on nucleation and crystal growth. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Studies on the growth and optical characterization of dysprosium gadolinium oxalate single crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2004A. Elizebeth Abstract Preparation and optical characterization of dysprosium gadolinium oxalate (DGO) single crystal is reported. The crystals were grown using silica gel technique, by the controlled reaction of rare earth nitrates with oxalic acid. Crystals were characterized using X-ray powder diffraction, optical absorption and fluorescence studies. Radiative transition probability, fluorescence branching ratio and radiative lifetime of Dy3+ in the crystal are evaluated by the parameterization of the absorption spectrum by the Judd-Ofelt theory. The recorded fluorescence spectrum showed two well resolved peaks at 480 nm and 571 nm and are assigned to the transitions from 4F9/2 , 6H15/2 and 6H13/2 of Dy3+. Stimulated emission crossection and optical gain of these transitions are also evaluated. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electrochemiluminescence Based on Solid State Tri(4,7-diphenyl-1,10-phenanthroline) Ruthenium(II) Ditetrakis(4-chlorophenyl) Borate Immobilized on Carbon FibersELECTROANALYSIS, Issue 12 2010Chunhua Liu Abstract A simple method for immobilization of tri(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ditetrakis(4-chlorophenyl) borate ([Ru(dpp)3][(4-Clph)4B]2) on carbon fiber electrodes was developed. Excellent electrochemical activity and electrochemiluminescence (ECL) signal of the coated carbon fiber electrodes were observed using oxalate as the co-reactant. In addition, the effects of pH, scan rate, nitrogen and oxygen on ECL intensity were also studied. To demonstrate the reliability, the coated carbon fiber electrodes were used as ECL detectors and very low concentration of phenol was detectable (5.0×10,8,M). [source] Kinetics and Mechanism of Ni(II) Chelation in Model and Real Solutions of Xylem Sap of Quercus ilexELECTROANALYSIS, Issue 22 2007Margarida, Maria Correia, Santos Abstract The kinetics of formation and dissociation of Ni(II) complexes with oxalic and citric acids was studied by cyclic voltammetry in model solutions of xylem sap of Q. ilex (the dominant tree growing on serpentine soils of Northeast Portugal) using representative concentrations, pH and ionic strength. The role of magnesium on complex formation was analyzed from solutions where Mg is present at concentration levels found in the xylem sap of Q. ilex growing on both nonserpentine and serpentine soils. Kinetics studies were also done in diluted solutions of real xylem sap samples, spiked with increasing amounts of magnesium. The values obtained for the apparent rate constants were those anticipated by the proposed model. To test the validity of the methodology and mechanisms, formation rate constants, kf (M,1 s,1) of Ni(II) complexes with citrate and oxalate were evaluated that compare with the values from Eigen mechanism. [source] Light-emitting diode-compatible probes for indirect detection of anions in CEELECTROPHORESIS, Issue 19 2007Peter Balding Abstract A range of compounds were evaluated as probes for the indirect detection of inorganic ions using CE and light-emitting diodes (LEDs) as the light source. Emphasis was placed on examining probes likely to absorb strongly in the UV,Vis region near 350,430,nm as compounds, which absorb at longer wavelengths tend to be bulkier and adsorb onto the capillary wall. These probes should act as a replacement for the very effective but carcinogenic probe chromate. Two probes were identified and evaluated: p -nitrophenol and 4-hydroxy-3,5-dinitrobenzoic acid. The former showed the most potential with low-mobility anions, while the later had a moderate electrophoretic mobility and was more suitable for a wider mobility range of analytes. However, neither could match the efficiencies and LOD of chromate for the separation of the fast inorganic ions such as chloride, nitrate and sulphate. Nevertheless, application of the 4-hydroxy-3,5-dinitrobenzoic acid system to the determination of oxalate in Bayer liquors showed excellent sensitivity and selectivity. [source] Arsenate toxicity for wheat and lettuce in six Chinese soils with different propertiesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2009Qing Cao Abstract To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation tests on wheat (Triticum aestivum L.) and lettuce (Lactuca sativa) were conducted in six Chinese soils freshly spiked with As. Plants were treated with 7 or 10 levels of As to establish concentration-effect curves. Median effective concentration and 10% effective concentration values were derived with regression analysis to measure As toxic potencies, and no-observed-effect concentration was determined by comparison with a control to elucidate thresholds of As to the two plant species. The median effective concentration values for As varied from 159 to 683 mg/kg for wheat and 59 to 426 mg/kg for lettuce, and the 10% effective concentration values varied from 79 to 270 mg/kg for wheat and 20 to 156 mg/kg for lettuce. The result suggests that lettuce is a more sensitive species for monitoring soil As contamination. With the same level of As spiked, soil toxicity for a plant showed a tendency of fluvoaquic soil toward red soil or black soil toward paddy soil. The phytotoxicity of As was negatively correlated with soil amorphous iron content extracted with ammonium oxalate. The overall results from the present work illustrate the necessity of considering soil properties in assessing soil As contamination. [source] Novel (3,4)- and (4,5)-Connected Lanthanide Metal,Organic FrameworksEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2008Xian-Wen Wang Abstract The three-dimensional lanthanide noninterpenetrating metal,organic frameworks formulated as [Ln(3,5-pdc)(C2O4)0.5(H2O)2]·H2O (Ln = LuIII, GdIII, TmIII and YbIII for complex 1,4, respectively; 3,5-pdc = 3,5-pyridinedicarboxylate) were synthesized by hydrothermal reactions of 3,5-H2pdc with lanthanide oxide and perchloric acid. Compound 1 shows (3,4)-connected (4.82)(4.85) dmc-type topological network, and complexes 2,4 display the novel (4,5)-connected (44.6.8)(44.62.84) xww-type topology. The lanthanide-mediated transformation of CO2 to oxalate under hydrothermal conditions was observed. The fluorescence properties of complexes 1,4 were investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Designed Assembly and Structures and Photoluminescence of a New Class of Discrete ZnII Complexes of 1H -1,10-Phenanthroline-2-oneEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2006Jie-Peng Zhang Abstract The hydrothermal reaction of 1H -1,10-phenanthroline-2-one (Hophen), zinc acetate, benzoic acid (Hba), and triethylamine (3.0 mL) yields the tetranuclear complex [Zn4(,3 -OH)2(ophen)4(ba)2] (2), which features a chair-like Zn4(,3 -OH)2 cluster with two ba ligands centrosymmetrically oriented. [(OAc){Zn3(,3 -OH)(ophen)3}(ox){Zn3(,3 -OH)(ophen)3}(OAc)] (3; ox = oxalate) was isolated when less triethylamine (1.0 mL) was used. Two Zn3(,3 -OH)(ophen)3 clusters in 3 are linked together by an oxalate to form a dumbbell-like structure in which the acetate and oxalate ligands point outward from the Zn3(,3 -OH)(ophen)3 cluster with an acute bending angle. A geometric analysis reveals that Zn3(,3 -OH)(ophen)3 and dicarboxylate with an obtuse bending angle cannot form an infinite zigzag chain, whereas the ring isomer can. With isophthalate (ipa), thiophene-2,5-dicarboxylate (tda), and 4,4,-oxybis(benzoate) (oba) instead of the acetate of 3 three new complexes, namely [{Zn3(,3 -OH)(ophen)3}(ipa)2{Zn3(,3 -OH)(ophen)3}]·0.5H2O (4), [{Zn3(,3 -OH)(ophen)3}(tda)2{Zn3(,3 -OH)(ophen)3}] (5), and [{Zn3(,3 -OH)(ophen)3}(oba)2{Zn3(,3 -OH)(ophen)3}] (6), were obtained in which two Zn3(,3 -OH)(ophen)3 clusters are linked by a pair of ipa, tda, or oba ligands to form isostructural, cluster-based 2:2 metallomacrocycles. Photoluminescence studies of 2,6 revealed that their luminescent properties are derived from ophen-based ,-,* excited states. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Syntheses, Crystal Structures and Magnetic Properties of Carboxylato-Bridged Polymeric Networks of MnIIEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2006Subal Chandra Manna Abstract Three new carboxylato-bridged polymeric networks of MnII having,molecular formula [Mn(ox)(dpyo)]n (1), {[Mn2(mal)2(bpee)(H2O)2]·0.5(bpee)·0.5(CH3OH)}n (2) and {[Mn3(btc)2(2,2,-bipy)2(H2O)6]·4H2O}n (3) [dpyo, 4,4,-bipyridine N,N,-dioxide; bpee, trans -1,2 bis(4-pyridyl)ethylene; 2,2,-bipy, 2,2,-bipyridine; ox = oxalate dianion; mal = malonate dianion; btc = 1,3,5-benzenetricarboxylate trianion] have been synthesized and characterized by single-crystal X-ray diffraction studies and low temperature magnetic measurements. Structure determination of complex 1 reveals a covalent bonded 2D network containing bischelating oxalate and bridging dpyo; complex 2 is a covalent bonded 3D polymeric architecture, formed by bridging malonate and bpee ligands, resulting in an open framework with channels filled by uncoordinated disordered bpee and methanol molecules. Whereas complex 3, comprising btc anions bound to three metal centers, is a 1D chain which further extends its dimensionality to 3D via - and H-bonding interactions. Low temperature magnetic measurements reveal the existence of weak antiferromagnetic interaction in all these complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Hexaazamacrocycle Containing Pyridine and Its Dicopper Complex as Receptors for Dicarboxylate AnionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2005Feng Li Abstract The host,guest binding interactions of the hexaazamacrocycle [26]py2N4, in its tetraprotonated form H4[26]py2N44+ as well as in its dicopper(II) complex [Cu2([26]py2N4)(H2O)4]4+, with dicarboxylate anions of different stereoelectronicrequirements, such as oxalate (ox2,), malonate (mal2,), succinate (suc2,), fumarate (fu2,) and maleate (ma2,), were evaluated. The association constants were determined using potentiometric methods in aqueous solution, at 298.0 K and 0.10 mol·dm,3 KCl. These values for the tetraprotonated ditopic receptor with the dicarboxylate anions revealed that the main species in solution corresponds to the formation of {H4[26]py2N4(A)}2+ (pH , 4,9), A being the substrate anion. The values determined are not especially high, but the receptor exhibits selectivity for the malonate anion. The study of the cascade complexes revealed several species in solution, involving mononuclear and dinuclear complexes, mainly protonated and hydrolysed species, as well as the expected complexes [Cu2([26]py2N4)(A)(H2O)x]2+ or [Cu2([26]py2N4)(A)2(H2O)y]. Ox2, and mal2, form cascade complexes with only one anion, which will necessarily bridge the two copper atoms because of the symmetrical arrangement of the dinuclear complex. The two other studied anions, suc2, and ma2,, form species involving two substrate anions, although species with only one suc2, anion were also found. UV/Vis and EPR spectroscopy have shown that the dicopper complex can operate as a sensor to detect and quantitatively determine oxalate spectrophotometrically because of the red shift of the maximum of the visible band observed by addition of ox2, to an aqueous solution of the dinuclear copper complex. However the selectivity of [Cu2([26]py2N4)(H2O)4]4+ as a receptor for ox2, in the studied series is not sufficiently high to detect ox2, spectrophotometrically in the presence of the other anions. Molecular dynamics simulations indicated that the H4[26]py2N44+ receptor provides a large and flexible cavity to accommodate the studied anions. Molecular recognition is based in electrostatic interactions rather than in multiple hydrogen-bonding interactions acting cooperatively. By contrast, the [Cu2([26]py2N4)]4+ receptor has a well-shaped cavity with adequate size to uptake these anions as bridging ligands with formation of four Cu,O bonds. The ox2, anion is encapsulated within the cascade complex while the remaining anions are located above the N6 macrocyclic plane, suggesting a selective coordination behaviour of this receptor. In spite of our molecular simulation being carried out in gas phase, the modelling results are consistent with the solution studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Tuning the Magnetic Properties of a Dinuclear Copper Complex: From Ferromagnetic to Antiferromagnetic CouplingEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2004Simon P. Foxon Abstract A novel structural motif in oxalate bridged copper(II) complexes has been prepared namely a metallamacrocyclic compound of the dinucleating ligand 1,3-bis[bis(2-pyridylmethyl)amino]benzene (= 1,3-tpbd). It could be demonstrated that the magnetic properties of copper(II) complexes of the 1,3-tpbd ligand can be adjusted from weakly ferromagnetic (J = +9.3 cm,1) to strongly antiferromagnetic [J = ,366(9) cm,1] by variation of the additional ligands (e.g. perchlorate, azide, oxalate etc.). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Inorganic sulphate extraction from SO2 -impacted AndosolsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2005T. Delfosse Summary Sulphate sorption on to the surface of short-range ordered minerals and precipitation of Al-hydroxy sulphate contribute to the acid neutralizing capacity of soils. The correct measurement of total inorganic sulphate is thus essential in soils that are accumulating SO42, anions. We extracted SO42, by various solutions, namely 0.005 m Ca(NO3)2, 0.016 m KH2PO4, 0.5 m NH4F and 0.2 m acidic NH4 -oxalate (pH 3), from Vitric and Eutric Andosols exposed to prolonged deposition of acid and SO2 from an active volcano (Masaya, Nicaragua). We attributed sulphate extractable by KH2PO4 (20,3030 mg kg,1) to anion-exchangeable SO42,, which was much smaller than NH4F- and oxalate-extractable SO42, (400,9680 and 410,10 480 mg kg,1, respectively). Our results suggest the occurrence of a sparingly soluble Al-hydroxy-mineral phase extractable by both NH4F and oxalate. The formation of Al-hydroxy minerals would result from the combination of enhanced weathering caused by strong acid loading and simultaneous occurrence of large SO42, concentrations in soil solution. Oxalate extracted slightly more inorganic SO42, than did NH4F, this additional amount of SO42, correlating strongly with oxalate-extractable Si and Fe contents. Preferential occlusion of SO42, by short-range ordered minerals, especially ferrihydrite, explains this behaviour. If we exclude the contribution of occluded sulphate then oxalate and NH4F mobilize similar amounts of SO42, and are believed to mobilize all of the inorganic SO42, pool. [source] Estimation of the phosphorus sorption capacity of acidic soils in IrelandEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2001R. O. Maguire Summary The test for the degree of phosphorus (P) saturation (DPS) of soils is used in northwest Europe to estimate the potential of P loss from soil to water. It expresses the historic sorption of P by soil as a percentage of the soil's P sorption capacity (PSC), which is taken to be , (Alox + Feox), where Alox and Feox are the amounts of aluminium and iron extracted by a single extraction of oxalate. All quantities are measured as mmol kg soil,1, and a value of 0.5 is commonly used for the scaling factor , in this equation. Historic or previously sorbed P is taken to be the quantity of P extracted by oxalate (Pox) so that DPS = Pox/PSC. The relation between PSC and Alox, Feox and Pox was determined for 37 soil samples from Northern Ireland with relatively large clay and organic matter contents. Sorption of P, measured over 252 days, was strongly correlated with the amounts of Alox and Feox extracted, but there was also a negative correlation with Pox. When PSC was calculated as the sum of the measured sorption after 252 days and Pox, the multiple regression of PSC on Alox and Feox gave the equation PSC = 36.6 + 0.61 Alox+,0.31 Feox with a coefficient of determination (R2) of 0.92. The regression intercept of 36.6 was significantly greater than zero. The 95% confidence limits for the regression coefficients of Alox and Feox did not overlap, indicating a significantly larger regression coefficient of P sorption on Alox than on Feox. When loss on ignition was employed as an additional variable in the multiple regression of PSC on Alox and Feox, it was positively correlated with PSC. Although the regression coefficient for loss on ignition was statistically significant (P <,0.001), the impact of this variable was small as its inclusion in the multiple regression increased R2 by only 0.028. Values of P sorption measured over 252 days were on average 2.75 (range 2.0,3.8) times greater than an overnight index of P sorption. Measures of DPS were less well correlated with water-soluble P than either the Olsen or Morgan tests for P in soil. [source] The prothrombin gene is expressed in the rat kidneyFEBS JOURNAL, Issue 1 2000Implications for urolithiasis research There is considerable interest in determining the role of prothrombin fragments, especially urinary prothrombin fragment 1 (UPTF1), in the pathogenesis of calcium oxalate (CaOx) urinary calculi. This fragment is present in abundance in the matrix of CaOx crystals generated in human urine in vitro and has also been detected in human urinary stones containing calcium. More recently, prothrombin gene expression has been reported in the human kidney. However, studies examining the renal biosynthesis of prothrombin or perhaps only its fragments during experimental lithogenesis, and in consequence, the role of UPTF1 in stone formation, cannot be carried out in humans. The aim of this investigation therefore was to determine whether prothrombin gene expression is present in the rat kidney. Total RNA was isolated from the kidneys and livers of 12 rats. Using reverse transcriptase PCR, mRNAs corresponding to the thrombin and fragment 1 + 2 (F1+2) regions of prothrombin were analysed by agarose gel electrophoresis. The expression of glyceraldehyde 3-phosphate dehydrogenase was also examined to determine whether the quality of the tissue mRNAs was adequate for analyses. The amplified products were identified by sequence analysis. All kidneys displayed evidence of expression of the thrombin and F1+2 domains of the prothrombin gene. Furthermore, the sequences of these PCR-derived products from kidney were identical to those from liver. This suggests that the prothrombins secreted by these two organs are identical. The fact that prothrombin biosynthesis occurs in both the human and rat kidney presents an opportunity for using established rat models of stone disease to evaluate the influence of lithogenic conditions on prothrombin gene expression, and the potential role of UPTF1 in vivo. [source] Numerical taxonomic evaluation of calcium oxalate and calcium carbonate crystals in the leaves of certain Ficus species (Moraceae)FEDDES REPERTORIUM, Issue 5-6 2004S. M. Sharawy Dr. The type and the distribution of calcium oxalate and calcium carbonate crystals were investigated in the leaves of 33 taxa of Ficus belonging to the three subgenera Urostigma, Ficus and Sycomorus for a speculation to the inter-subgeneric affinity. Numerical analysis of 55 characters grouped the taxa under 13 groups. The sizes of the latter with respect to the number of taxa they contain were calculated. Some resultant groups comprised taxa from different subgenera. So far as the present data are concerned and in agreement with previous workers, the var. decora of Ficus elastica and var. comosa of Ficus benjamina are better raised to the specific levels F. decoraHort and F. comosaRoxb. respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Numerisch-taxonomische Auswertung von Calciumoxalat- und Calciumcarbonat-Kristallen in einigen Arten der Gattung Ficus (Moraceae) An den Blättern von 33 Taxa der Gattung Ficus aus den drei Subgenera Urostigma, Ficus und Sycomorus wurden die Art und die Verteilung von Calciumoxalat- und Calciumcarbonat-Kristallen untersucht, um ihre inter-subgenerische Verwandtschaft zu ermitteln. Num-merische Analysen von 55 Eigenschaften gestatten eine Unterteilung in 13 Gruppen. Der Umfang letzterer in Bezug auf die Anzahl der sie umfassenden Taxa wurde betrachtet. Einige dieser Gruppen umfassen Taxa aus unterschiedlichen Subgenera. Auf Grund der hier gewonnenen Daten und in Übereinstimmung mit früheren Bearbeitern werden Ficus elastica var. decora und F. benjamina var. comosa in den Artrang F. decoraHort bzw. F. comosaRoxb. erhoben. [source] Impact of nutritional supplements and monosaccharides on growth, oxalate accumulation, and culture pH by Sclerotinia sclerotiorumFEMS MICROBIOLOGY LETTERS, Issue 1 2007Bryan J. Culbertson Abstract Sclerotinia sclerotiorum D-E7 was studied to determine the impact of nutritional supplements and monosaccharides on growth, oxalate accumulation, and culture pH in broth media (initial pH c. 5). Cultures with 0.1% nutritional supplement (tryptone, yeast extract, or soytone) yielded minimal growth, 2,3 mM oxalate, and a final culture pH of 4.2,4.8. In contrast, cultures with 0.1% nutritional supplement and 25 mM glucose yielded significant growth, minimal oxalate (<1 mM), and a final culture pH of 2.8,3.7. Similar trends were observed when glucose in 0.1% soytone cultures was replaced with 25 mM d -mannose, l -arabinose, or d -xylose. With 1% soytone-25 mM glucose cultures, growth and oxalate accumulation (,21 mM) occurred with little change in initial pH. This was not the case with 1% soytone-250 mM glucose cultures; increased glucose levels resulted in a decrease in oxalate accumulation (,7 mM) and in final culture pH (3.4). Time-course studies with these cultures revealed that oxalate accumulation was suppressed during growth when the culture pH dropped to <4. Overall, these results indicate that (1) the decrease in external pH (i.e. acidification) was independent of oxalate accumulation and (2) acidification coupled to glucose-dependent growth regulated oxalate accumulation by Sclerotinia sclerotiorum. [source] Production of oxalates In Vitro by Microbes Isolated from Rock Surfaces with prehistoric paints in the Lower Pecos Region, TexasGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 1 2008Darren Hess Calcium oxalate-rich rock coatings are ubiquitous on limestone inside dry rock shelters and under bluff overhangs along canyon walls in southwestern Texas. Prehistoric pictographs occur in more than 250 such sites, and the ancient paints are encapsulated within the natural rock coating. Previous studies suggest lichens were the source of the oxalate; however, we report here that microbes cultured and isolated from samples of the coating produce oxalate in vitro. Twenty different bacteria species have been identified in samples from eight different sites, with Bacillus the most common genus, represented by five species. HPLC analyses of inoculated R2B medium after eight months of bacterial growth revealed the presence of oxalate ions in the solid phase of the growth medium. © 2008 Wiley Periodicals, Inc. [source] Effect of application form of nitrogen on oxalate accumulation and mineral uptake by napiergrass (Pennisetum purpureum)GRASSLAND SCIENCE, Issue 3 2010Mohammad Mijanur Rahman Abstract Oxalate occurs naturally in forage species, but excess levels of soluble oxalate adversely affect their nutritional quality as animal feed. Although induction of oxalate in plants has been associated with nitrate application, relatively little is known about oxalate in forage grasses. In the present study, we investigated oxalate accumulation and mineral uptake by napiergrass (Pennisetum purpureum, cv. dwarf-late) cultured in complete nutrient solution containing either solely nitrate or mainly ammonium as the main form of nitrogen. Total (shoot and root) yield of plants did not differ significantly between the nitrate and ammonium treatments. By contrast, the nitrogen form significantly affected oxalate accumulation and mineral uptake by plants. Nitrate application resulted in higher concentrations of soluble and insoluble oxalates in the shoot and soluble oxalate in the root than ammonium application. Nitrate application also resulted in higher concentrations of sodium and calcium in the shoot, and higher concentrations of sodium, calcium and magnesium in the root than ammonium application. The results suggest that the application of nitrate fertilizer as the sole source of nitrogen should be avoided in the cultivation of oxalate-rich forages, though further studies are needed under field conditions. [source] Effects of season, variety and botanical fractions on oxalate content of napiergrass (Pennisetum purpureum Schumach)GRASSLAND SCIENCE, Issue 4 2006M. M. Rahman Abstract Various tropical grasses sometimes contain oxalate in sufficient concentration as to induce calcium deficiency in grazing animals. Napiergrass (Pennisetum purpureum), a useful tropical grass for ruminants was examined for oxalate levels with regard to season, variety and botanical fractions. It was observed that oxalate content was significantly (P < 0.001) affected by the season with the highest value (3.77%) being associated with early summer samples and the lowest value (1.76%) with late autumn samples. Compared to a normal, non-dwarf variety, a dwarf variety exhibited a higher oxalate content but the difference was not statistically significant. With regard to the botanical fractions, oxalate content was significantly (P < 0.05) higher (2.78%) in leaf tissues compared to stem with leaf sheath (2.05%). In another experiment, a late, dwarf variety was re-grown four times to evaluate re-growth period effects on oxalate content during the early summer. Oxalate content increased gradually from the re-growth period 1 (6 June to 28 June) to re-growth period 3 (21 June to 12 July), and declined in re-growth period 4 (28 June to 19 July). Results suggest that when napiergrass is grown in early summer, it could achieve oxalate levels that are toxic to ruminants. [source] Kidney stone disease and risk factors for coronary heart diseaseINTERNATIONAL JOURNAL OF UROLOGY, Issue 10 2005SATOSHI HAMANO Abstract Background:, We conducted a case-control study to examine the impact of coronal heart disease (CHD) risk factors on calcium oxalate (CaOX) stone formation. Methods:, Variables included body mass index (BMI), current alcohol use, smoking habit, hypertension, hypercholesterolemia, diabetes mellitus, and hyperuricemia. Data suf,cient for analysis were obtained for 181 CaOX stone formers and 187 controls. Results:, Seven of 181 stone formers (3.9%) had a history of CHD compared with none of 187 control subjects (P = 0.007). In univariate logistic regression analysis, smoking habit (OR 4.41, 95% CI 2.85,6.84, P < 0.0001), hypertension (OR 4.24, 95% CI 2.61,6.91, P < 0.0001), hypercholesterolemia (OR 3.03, 95% CI 1.77,5.20, P < 0.0001) and BMI (OR 1.10, 95% CI 1.04,1.17, P = 0.007) reached statistical signi,cance. In a multivariate logistic regression analysis, smoking habit (OR 4.29, 95% CI 2.68,6.86, P < 0.0001), hypertension (OR 3.57, 95% CI 2.11,6.07, P < 0.0001), and hypercholesterolemia (OR 2.74, 95% CI 1.51,5.00, P = 0.001) reached statistical signi,cance, while BMI (OR 1.06, 95% CI 0.99,1.12, P = 0.09) did not. Conclusions:, CaOX stone formers are signi,cantly associated with several CHD risk factors, including smoking habit, hypertension, hypercholesterolemia, and obesity. [source] Oxalate-degrading Providencia rettgeri isolated from human stoolsINTERNATIONAL JOURNAL OF UROLOGY, Issue 6 2005SANEHIRO HOKAMA Abstract Background:, Oxalate-degrading bacteria are thought to metabolize intestinal oxalate and thus decrease the urinary excretion of oxalate by reducing its intestinal absorption. Methods:, We have isolated several novel oxalate-degrading bacteria from human stools. Oxalate degrading bacteria were investigated to characterize their protein profiles with antibodies against oxalyl-coenzyme A decarboxylase (65 kDa) and formyl-coenzyme A transferase (48 kDa) purified from Oxalobacter formigenes. Results:, One of these isolates was identified as Providencia rettgeri, which showed two proteins (65 kDa and 48 kDa) on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) that were not found in non-oxalate-degrading P. rettgeri. Antibodies reacted with the 65 and 48 kDa proteins from the P. rettgeri strain on Western blotting. An Oxalobacter formigenes formyl-coenzyme A transferase gene probe reacted with chromosomal DNA from P. rettgeri on Southern blotting under high stringency conditions, while an Oxalobacter formigenes oxalyl-coenzyme A decarboxylase gene probe did not react under the same conditions. Conclusions:, The mechamism of oxalate degradation by P. rettgeri appears to be similar to that of Oxalobacter formigenes. This is the first report of a facultative oxalate-degrading organism that is one of the Enterobacteriaceae. [source] Renal silica calculi in an infantINTERNATIONAL JOURNAL OF UROLOGY, Issue 2 2004TOSHIYUKI NISHIZONO Abstract, We report on a rare case of urinary silica calculi in a 10-month-old boy. The boy showed acute pyelonephritis with left hydronephrosis. Ultrasonography and computed tomography revealed a calculus at the left ureteropelvic junction and three additional calculi in the left renal pelvis. Because his acute pyelonephritis was refractory to conventional chemotherapy, the patient underwent successful left percutaneous nephrostomy followed by percutaneous nephrolithotripsy for the renal calculi. All stones disappeared and his postoperative course was uneventful. On infrared spectrophotometry, the wavelength pattern of the stones exhibited two peaks at 1100 and 1650 cm,1, consistent with the determination that the calculi consisted of a mixture of silicate (78%) and calcium oxalate (22%). We consider that the etiology of the calculi in this child can be ascribed to the silicate-rich water used to dilute milk. In Japan, 46 adult patients with urinary silicate calculi have been reported in the literature; however, there is no report of the disease in an infant in Japan. [source] Association of absence of intestinal oxalate degrading bacteria with urinary calcium oxalate stone formationINTERNATIONAL JOURNAL OF UROLOGY, Issue 6 2003KAZUO MIKAMI Abstract Aim: Urinary concentration of oxalate is considered an important factor in the formation of renal stones. Dietary oxalate is a major contributor to urinary oxalate excretion in most individuals. Furthermore, oxalate degrading bacteria have been isolated from human feces. We investigated the significance of oxalate degrading bacteria for urinary oxalate excretion and urinary stone formation. Methods: Twenty-two known calcium oxalate stone-forming patients (stone formers) and 34 healthy volunteers (non-stone formers) were included in the study. Stool specimens were inoculated into pepton yeast glucose (PYG) medium supplemented with oxalate under anaerobic condition at 37 C for one week. After the incubation period, each colony was checked for the loss of oxalate from the culture medium. A 24-h urine sample was collected in 43 individuals and analyzed for oxalate excretion. Results: Twenty-eight of 34 (82%) healthy volunteers and 10 of 22 (45%) calcium oxalate stone formers were colonized with oxalate degrading bacteria. Calcium oxalate stone formers were more frequently free of oxalate degrading bacteria (P < 0.01). Urinary excretion of oxalate in those with oxalate degrading bacteria was significantly less than in those without oxalate degrading bacteria (P < 0.05). Hyperoxaluria (> 40 mg/day) was found in four of 27 individuals (15%) with oxalate degrading bacteria compared to seven of 16 (44%) without oxalate degrading bacteria (P < 0.05), suggesting an association between the absence of oxalate degrading bacteria and the presence of hyperoxaluria. Conclusion: The absence of oxalate degrading bacteria in the gut could promote the absorption of oxalate, thereby increasing the level of urinary oxalate excretion. The absence of oxalate degrading bacteria from the gut appears to be a risk factor for the presence of absorptive hyperoxaluria and an increased likelihood of urolithiasis. [source] | ||||||||||||||||||||||||||||||||||||||||