Mixed Phosphate Research Articles

Modulation of polycaprolactone composite properties through incorporation of mixed phosphate glass formulations

Phosphate-based glasses (PGs) and their composites are of interest as bone repair and tissue engineering scaffolds due to the totally degradable nature of the materials. This study has investigated the effect of Si and Fe on the properties of PG particulate-filled polycaprolactone (PCL) matrix composites. Two glass compositions were investigated (mol.%): 50P(2)O(5), 40CaO and 10SiO(2) or Fe(2)O(3) (Si(10) and Fe(10), respectively). All composites contained 40 vol.% particulate filler, either Si(10), Fe(10), or a blend (40Si(10)/0Fe(10), 30Si(10)/10Fe(10), 20Si(10)/20Fe(10), 10Si(10)/30Fe(10) or 0Si(10)/40Fe(10)). Ion release, weight loss and composite mechanical properties were characterised as a function of time in deionised water (DW) and phosphate-buffered saline (PBS), respectively. The potential for calcium phosphate deposition was assessed in simulated body fluid (SBF). Calcium and phosphate ion release in DW increased in tandem with the rate of composite weight loss, which increased with Si(10) content. A Si(10) content dependent rate of pH reduction was observed in DW. After 56 days the PG in the 40Si(10)/0Fe(10) composite was completely dissolved, whereas 67% of that in the 0Si(10)/40Fe(10) composite remained. The initial flexural strength of 40Si(10)/0Fe(10) composites was significantly lower when compared with the other materials. An increase in Si(10) content led to an increase in Young's modulus and a concomitant decrease in flexural strain. It was found that the PCL molecular weight (M(w)) decreased dramatically with increasing Si(10) content. FTIR analysis showed that Si incorporation into PG led to reaction with the PCL ester bonds, resulting in a reduction in PCL M(w) when processed at elevated temperatures. Changes in mechanical properties with time in PBS were glass blend dependent and a more rapid rate of reduction was observed in higher Si(10) content composites. After 28 days in SBF surface deposited brushite was formed in 20Si(10)/20Fe(10) PG containing composites. Thus, the properties of PCL-PG composites could be tailored by controlling the phosphate glass blend composition.

Solid-state interactions of vanadium and phosphorus oxides in the closed systems

Physicochemical processes during thermal treatment of vanadium and phosphorus oxides mixture (1) as well as with diammonium hydrophosphate (2) in the closed system (autoclave) have been studied. In the first case, at 300 °C, the defective structure γ-VOPO4 is formed and in the second case, there was established possibility of synthesis of vanadyl hydrophosphate—the precursor of vanadyl pyrophosphate (the catalyst of n-butane oxidation to maleic anhydride). At the same time, various phases of mixed ammonium and vanadium phosphates were obtained at lower and higher temperatures.

Calcium–strontium mixed phosphate as novel injectable and radio-opaque hydraulic cement

Sterile calcium hydrogenophosphate dihydrate (DCPD) (CaHPO(4).2H(2)O), calcium oxide and strontium carbonate powders were mixed in various liquid phases. Among these, ammonium phosphate buffer (0.75 M, pH 6.9) led to a novel strontium-containing calcium phosphate cement. At a 6/2.5/1.5 M ratio and for a liquid to powder ratio (L/P) of 0.5 mlg(-1), the initial paste was fluid and remained injectable for 12 min at 25 degrees C. It was easily obtained by mixing sterile powders and the liquid phase using the push-pull technique, avoiding complex mixing apparatus. The cement set after 15 min at 37 degrees C and was hard after 1h. The compressive strength was in the 20 MPa range, a value higher than that generally assigned to trabecular bone (5-15MPa). This strength appeared sufficient for repairing non-loading sites or reinforcing osteoporotic vertebrae (vertebroplasty). After setting, the initial mixture formed a strontium-calcium-deficient carbonate apatite. The radio-opacity of the resulting cement was three times greater than that of cortical bone because of the presence of strontium ions, a feature that complies with the requirements for vertebroplasty. Furthermore, the cement powder remained stable and retained its properties for at least 4 years.

Crystalline composition and etiologic factors of kidney stone in Thailand : update 2007

Objective: The etiology of kidney stone is multifactorial including environmental, behavioral and genetic. Insights about predisposing causes and mineral composition are mandatory for better management of kidney stone disease. The present hospital-based study aims to explore the mineral constituents and etiologic risks of kidney stones in Thai patients from the four geographic regions of the country. Method: Two hundred and fifty six kidney stone patients from four geographic regions of Thailand, including the northeastern (n=103), the northern (n=81), the central (n=47) and the southern (n=25) were recruited in this study. Of these, 144 patients completed the food frequency questionnaire to assess the kidney stone risk. Mineral composition of stones were analyzed by Fourier transformed infrared spectrometry. Results: Kidney stone frequently affected peoples aged 40-49 years. Only 31.9 % of patients had a positive family history of renal stone. Calcium oxalate (CaOx) stone was the most prevalent type (73.8 %). Uric acid (UA) stone was found in 16.0 % commonly affected peoples aged 60-70 years. Mixed stones, notably CaOx mixed with calcium phosphate (CaP), were more prevalent than pure stones. The food frequency questionnaire data showed that 59.7 % of stone patients consumed less than two liters of water per day. Low intakes of fruits and vegetables were notably present. In contrast, high consumption of rice was observed in over 65 % of stone patients. Conclusion: CaOx mixed with CaP was the most prevalent stone type. UA stone was more likely to occur in the elderly. Kidney stone patients were found to consume less-than-adequate amounts of water, food high in carbohydrates, along with low consumtion of fruits and vegetables. These dietary habits might be risk factors in stone development among the Thai population. Keywords: Dietary risk factor, family history of renal stone, kidney stone risk factor, nephrolithiasis, stone composition.

Protein Hydrolysate of Salted Duck Egg White as a Substitute of Phosphate and Its Effect on Quality of Pacific White Shrimp (Litopenaeus Vannamei)

Protein hydrolysate from salted egg white (PHSEW) with different degrees of hydrolysis (DH) (3%, 6%, and 9%) was produced using pepsin. Disappearance of proteins with molecular weight (MW) of 108 and 85 kDa with the concomitant formation of proteins with MW of 23, 20, 13, and 5 kDa was observed in PHSEW. The use of PHSEW for quality improvement of Pacific white shrimp (Litopenaeus vannamei) was investigated. Shrimp soaked in 4% NaCl containing 7% PHSEW and 2.5% mixed phosphates (0.625% sodium acid pyrophosphate [SAPP] and 1.875% tetrasodium pyrophosphate [TSPP]) had the highest cooking yield with the lowest cooking loss (P < 0.05), compared with shrimps with other treatments. Nevertheless, no difference in weight gain was obtained in comparison with those treated with 4% NaCl containing 3.5% mixed phosphate (P > 0.05). Cooked shrimp treated with 4% NaCl containing 7% PHSEW and 2.5% mixed phosphate or those treated with 4% NaCl containing 3.5% mixed phosphate had the higher score of appearance, texture, and overall likeness but less shear force, in comparison with the control (no treatment) (P < 0.05). Microstructure study revealed that muscle fibers of cooked shrimp from both treatments had the swollen fibrils and gaps, while the control had the swollen compact structure. Therefore, use of PHSEW could reduce phosphate residue in shrimps without an adverse effect on sensory properties.

Using Computed Tomography to Predict in Vivo Stone Chemical Composition

Objectives Several authors hypothesized the usefulness of the non-contrast helical computed tomography (NCHCT) with the determination of stone Hounsfield Unit (HU) values in order to predict urinary stone compositions. Preoperative knowledge of stone composition might be interesting in pre-operative decision-making process. The aim of this study was to evaluate the possible correlation between stone chemical composition and correspondent stone HU value in an in-vivo experience. Methods Forty patients with urinary stones were preoperatively studied with abdominal NCHCT, where stone HU values were reported. Stone chemical composition was obtained in each patient, using the colorimetric method. The HU value of each stone was compared with the correspondent chemical analysis. Results The median HU values of calcium oxalate (n=10), mixed calcium oxalate and phosphate (n=19), calcium phosphate (n=2), uric acid (n=6) and mixed uric acid and calcium oxalate (n=3) stones were 1060 HU [interquartile range (IQR) 743.75–1222.5]; 900 HU (IQR 588.5–1108.5); 774 HU (range 720–828); 371 HU (IQR 361.25–436.25) and 532 HU (range 476–626), respectively. Conclusions Our results confirmed a statistically significant difference of the HU values between calcium and pure uric acid calculi, suggesting a correlation between stone chemical composition and CT-density. Hounsfield unit

Thermochemistry of the mixed calcium phosphate Ca 8P 2O 7(PO 4) 4

The calcium mixed phosphate Ca 8P 2O 7(PO 4) 4 has been synthesized by thermal decomposition of octacalcium phosphate previously prepared by precipitation in ammoniacal phosphate solution. The enthalpy of formation at 298.15 K referenced to β-tricalcium phosphate and calcium pyrophosphate is determined. β-Tricalcium phosphate was prepared by two methods: precipitation in ammoniacal aqueous medium and high temperature solid-state reaction. Calcium pyrophosphate was prepared by high temperature solid-state reaction. All the compounds are characterized by chemical analysis, X-rays diffraction and IR spectroscopy. The enthalpy of formation +10.83 ± 0.63 kJ mol −1 is obtained by solution calorimetry at 298.15 K in nitric acid.

Indirect cathodic electrocatalytic degradation of dimethylphthalate with PW 11O 39Fe(III)(H 2O) 4− and H 2O 2 in neutral aqueous medium

Cyclic voltammetry and degradation of dimethylphthalate (DMP) revealed that the iron-substituted heteropolytungstate anion PW 11O 39Fe(III)(H 2O) 4− is an excellent indirect cathodic oxidative electrocatalyst in the presence of H 2O 2. PW 11O 39Fe(III)(H 2O) 4− can electrocatalyze the reduction of H 2O 2 to hydroxyl radicals via an inner-sphere electron transfer mechanism, which cause oxidative decomposition of DMP. Almost complete DMP removal and ca. 30% mineralization were obtained in less than 120 min in a mixed phosphate solution at pH 6.86 containing 0.1 mM DMP. MS analyses of the intermediates and final products suggested that glyoxal, oxalic acid and acetic acid are the main ring-opening products, besides some unstable hydroxylated aromatic intermediates. The effects of added H 2O 2 concentration, applied cathodic potential and DMP initial concentration on the degradation of DMP were also investigated. A concentration of 1.0 mM H 2O 2 and cathodic potential of −0.3 V were optimal conditions for DMP degradation in our experiments. At higher initial DMP concentrations degradation also occurred, but at a slower decay rate compared to lower initial concentrations. The present system thus represents a possible method to use PW 11O 39Fe(III)(H 2O) 4− as an indirect cathodic oxidative electrocatalyst in water and wastewater treatment.

A near-infrared spectroscopic study of the phosphate mineral pyromorphite Pb 5(PO 4) 3Cl

Spectral properties as a function composition are analysed for a series of selected pyromorphite minerals of Australian origin. The minerals are characterised by d–d transitions in NIR from 12,000 to 8000 cm −1 (0.83–1.25 μm). A broad signal observed at ∼10,000 cm −1 (1.00 μm) is the result of ferrous ion impurity in pyromorphites and follows a relationship between band intensity in the near-infrared spectra and ferrous ion concentration. The iron impurity causes a change in colour from green-yellow to brown in the pyromorphite samples. The observation of overtones of the OH − fundamentals, confirms the presence OH − in the mineral structure. The contribution of water–OH overtones in the NIR at 5100 cm −1 (1.96 μm) is an indication of bonded water in the minerals of pyromorphite. Spectra in the mid-IR show that pyromorphite is a known mixed phosphate and arsenate complex, Pb 5(PO 4,AsO 4) 3Cl. A series of bands are resolved in the infrared spectrum of pyromorphite at 1017, 961 and 894 cm −1. The first two bands are assigned to ν 3, the antisymmetric stretching mode and the third band at 894 cm −1 is the symmetric mode of the phosphate ion. Similar patterns are shown by other pyromorphite samples with variation in intensity. The cause of multiple bands near 800 cm −1 is the result of isomorphic substitution of (PO 4) 3− by (AsO 4) 3− and the spectral pattern relates to the chemical variability in pyromorphite. The presence of (AsO 4) 3− is significant in certain pyromorphite samples.

Properties, Translucence, and Microstructure of Pacific White Shrimp Treated with Mixed Phosphates as Affected by Freshness and Deveining

Effects of freshness and deveining on some properties, translucence, and microstructure of Pacific white shrimp (Litopenaeus vannamei) soaked in 2.5% NaCl containing different phosphates were studied. Shrimp soaked in all solutions had increases in weight gain and cooking yield with lowered cooking loss, compared with the control (P < 0.05). However, efficacy of mixed phosphates in quality improvement of ice-stored shrimp was lower than fresh shrimp. Deveining resulted in increased weight gain and yield (P < 0.05). Nevertheless, samples treated with phosphates became more translucent. Shrimp stored in ice for 7 d and treated with mixed phosphates were generally more translucent than fresh counterparts (P < 0.05). Shrimp soaked in 2.5% NaCl containing 0.875% sodium acid pyrophosphate (SAPP) and 2.625% tetrasodium pyrophosphate (TSPP) were generally less translucent and had high weight gain and cooking yield along with low cooking loss. The microstructure study revealed that the muscle fibers were less attached with the loss of Z-disks after being treated with mixed phosphates. Cooked meats of fresh shrimp and ice-stored shrimp had more compact fiber arrangement with the shrinkage of sarcomere compared with raw samples. Disintegration was observed at the M-line in ice-stored shrimp treated with mixed phosphates after cooking, while such a phenomenon was not found in the cooked fresh sample treated with phosphates. T(max) and enthalpy of both myosin and actin peaks shifted to lower values when shrimp were treated with mixed phosphates (P < 0.05). Those changes were generally more pronounced in ice-stored shrimp. Therefore, freshness and deveining process had an impact on the quality of Pacific white shrimp treated with phosphates.

Mono-and bis(5-O-nitro-1,4:3,6-dianhydro-D-sorbit-2-yl) phosphates: synthesis and reactions with hydroxy-and amino-containing compounds

The reaction of 1,4:3,6-dianhydro-D-sorbitol 5-nitrate with POCl3 afforded mono-and bis(5-O-nitro-1,4:3,6-dianhydro-D-sorbit-2-yl) phosphorochloridates, whose hydrolysis resulted in phosphoric acid mono-and diesters. The subsequent treatment of these compounds with bases gave sodium and cyclohexylammonium salts. The reactions of phosphorochloridates with phenol, pentaerythritol dibromohydrin, and ethylenimine in the presence of organic bases afford mixed phosphates and phosphoramidates.

Ceramics based on mixed zirconium phosphate prepared by solar-furnace melting

A solar technology to synthesize an NZP structure using the example of Zr(PO4) was developed. The method is based on high-temperature chemical reactions in the melt and subsequent crystallization of the hexagonal structure of the compounds of this class. Ceramic samples were prepared from the material obtained, and the processes of their sintering were studied.

Subchronic Oral Toxicity Study of Mixed Tocopheryl Phosphates in Rats

Rats were fed diets containing 0%, 1%, 3%, or 5% mixed tocopheryl phosphates for 90 days. No abnormal clinical signs related to treatment appeared. Some statistically significant changes in hematology and clinical chemistry parameters appeared, but the majority were not dose dependent, occurred in only one sex or group, and/or remained within the historical control range for this strain of rat. A statistically significant apparent reduction in blood protein was observed in animals treated with the tocopheryl phosphates, but further investigation showed that the test substance interfered with the protein assay. Repeat analysis using a method unaffected by plasma test substance levels showed no difference in plasma proteins among all groups. Gross necropsy revealed no abnormalities; reduced relative heart and epididymal weights were observed, but were not dose dependent and were considered incidental. Histopathological changes occurred only in the mesenteric lymph node and small intestine. Foreign material in a crystal-like form appeared in macrophages in both organs, and increased in a dose-related fashion. In the lymph node, sinus histiocytosis increased with dose, but the severity was similar between the control and low-dose groups. Foreign-body granulomatous inflammation, associated with Maltese cross birefringence of the crystals was seen in the mid- and high-dose animals, but not the low-dose group. Similarly, the small intestine showed increasing amounts of foreign material and inflammation in the mid- and high-dose but not in the 1% diet. The 1% diet (equivalent to 587 and 643 mg mixed tocopheryl phosphates/kg body weight/day for male and female rats, respectively) was considered the no observed adverse effect level.

Jasminaldehyde Synthesis Catalyzed by Al(Ga)PON Oxynitrides: Influence of the Reaction Conditions

Nitridation of amorphous aluminium phosphate (AlPO4) and mixed aluminium gallium phosphate (Al0.5Ga0.5PO4) under ammonia flow allows preparing “AlPON” and “AlGaPON” bifunctional acid-base heterogeneous catalysts. Their acid-base bi-functional character allows their use as selective catalysts for the production of jasminaldehyde through the cross-condensation of heptanal and benzaldehyde, followed by the dehydration of the aldol intermediate product. Three parameters enabling to maximize the jasminaldehyde yields in a batch reactor operated at 125°C were investigated: the catalyst composition (Al/Ga and O/N ratio), the reactant concentration and the amount of catalyst in the reactor. Maximum jasminaldehyde selectivities were obtained for intermediate nitrogen contents (7-10 wt.%). Maximum reaction rates were obtained using pure reactants and a catalysts weight equal to 10% of the total reagent weight.

Synthesis and Biological Evaluation of Phosphate Prodrugs of 4‐Phospho‐D ‐erythronohydroxamic Acid, an Inhibitor of 6‐Phosphogluconate Dehydrogenase

We have previously reported the discovery of potent and selective inhibitors of 6-phosphogluconate dehydrogenase, the third enzyme of the phosphate pentose pathway, from Trypanosoma brucei, the causative organism of human African trypanosomiasis. These inhibitors were charged phosphate derivatives with restricted capacity to enter cells. Herein, we report the synthesis of five different classes of prodrugs: phosphoramidate; bis-S-acyl thioethyl esters (bis-SATE); bis-pivaloxymethyl (bis-POM); CycloSaligenyl; and phenyl, S-acyl thioethyl mixed phosphate esters (mix-SATE). Prodrugs were studied for stability and activity against the intact parasites. Most prodrugs caused inhibition of the growth of the parasites. The activity of the prodrugs against the parasites appeared to be related to their stability in aqueous buffer.

93Nb and 17O NMR chemical shifts of niobiophosphate compounds

Niobiophosphate compounds with a large range of niobium and oxygen environments were studied with 93Nb and 17O solid-state NMR. 93Nb isotropic chemical shift of pure niobate Nb(ONb) 6, pure phosphate Nb(OP) 6 and mixed phosphate–niobate Nb(OP) x (ONb) (6− x ) (1⩽ x⩽5) sites were measured at a high magnetic field (18.8 T). 93Nb chemical shifts were found to be sensitive to the variation of local charge on Nb, but not to the local bond geometry (i.e. crystallographic site and edge or corner connectivity). A systematic shift to high field of the 93Nb chemical shift is measured when x increases. Then, 17O NMR spectra of a series of enriched samples provided the chemical shift and quadrupolar parameters for 4 types of oxygen environment (P–O–P, P–O–Na, P–O–Nb and Nb–O–Nb). Finally, Nb–O–Nb sites were characterized by a large 17O chemical shift anisotropy.

Synthesis and thermal characterization of copper and calcium mixed phosphates

A series of compounds with composition of Ca1–xCuxHPO4, where x varied from 0.05 to 0.5 were synthesized by precipitation method. The compounds were characterized by elemental analysis, X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and thermogravimetry. The chemical stabilities of solids were investigated at several pH. Elemental analysis of copper, calcium and phosphorus are in agreement with the proposed composition. The formation of lamellar phosphates was evidenced. The stability of the set of compounds was better for samples with high copper content.

POPULASI JAMUR MIKORIZA VESIKULAR-ARBUSKULAR PADA LAHAN BEKAS GALIAN EMAS YANG DIREKLAMASI DENGAN LEGUM TUMBUH CEPAT DIKOMBINASIKAN DENGAN PENUTUP TANAH DAN MIKROBA

A field work has been carried out to study the population of vesicular-arbuscular mycorrhizal (VAM) fungi on degraded gold mining land that was reclamated with fast growing legume (Enterolobium sp. and Acacia mangium) trees in combination with cover crops (Centrosema pubescen dan Flemingia congesta) and microbe (VAM fungi, Rhizobium sp. and mixed Rhizobium sp. and phosphate solubilizing bacteria) inoculation. Reclamation with fast growing legumes in combination with cover crops and microbe inoculation on the degraded land increased the population of VAM fungi. After 1.5 years, the population of the fungi on the reclamated land increased from 3.4 (control) to 6.1–80.5 spore/g soil. The highest spore population resulted by combination between Acacia mangium, C. pubescen, and VAM fungi (V2I1C1) plot followed by combination between Acacia mangium without cover crop, and VAM fungi inoculation (V2I1C0) plot and combination between Enterolobium sp. without cover crop and mixed Rhizobium and phosphate solubilizing bacteria inoculation (V1I3Co) plot were 80.5, 56.0 and 51.8 respectively.

Mixed phosphates K2MIIIMV(OPO4)2: Heterovalence-substituted analogs of KTiOPO4

A series of heterovalence-substituted analogs of KTiOPO4 of the general composition K2MIIIMV(OPO4)2 (MIII = Cr, Fe, In; MV = Nb, Ta) were synthesized by crystallization from melts and by solid-phase reactions. Influence of the nature of tri-and pentavalent metals on the conditions of preparation and on the features of phase formation of substituted mixed phosphates was examined. The compounds obtained were characterized by X-ray diffraction analysis and by diffuse reflection spectroscopy.

XPS analyses of lanthanides phosphates

XPS measurements were performed on lanthanide orthophosphates LnPO 4 (Ln: La, Ce, Nd, Gd), and correlated with XRD and some EDS analyses. Single lanthanide phosphates LnPO 4 and mixed lanthanide phosphates L n x L n ′ 1 − x P O 4 , all crystallized in a monoclinic structure similar to the monazite mineral. Results were examined qualitatively and quantitatively, by considering the Ln 3d lines, P 2p line and O 1s line. Ionic sputtering does not induce significant broadening nor an additional shift of the lanthanide peaks and does not have an effect on their chemical environments, except in the case of cerium. However, sputtering seems to significantly reduce the intensity of the O 1s and P 2p peaks, while Auger peaks of carbon and oxygen atoms interfere, respectively, with the 3d line of gadolinium and neodymium. Those phenomena are all the more important when the Nd and Gd content is weak and must be taken into account for a quantitative analysis of the spectra. The quantitative analyses reveal the expected results for single monazites. On mixed phosphates, the measured phosphorous and oxygen amounts are generally more valid for non-sputtered sample surfaces than for sputtered surfaces, while the calculated relative amount of lanthanides [Ln]/[Ln′] are correct in all the cases. One of the important goals of this work was to have a satisfactory value for the atomic ratio La/Gd, and particularly in the case of (La,Ce)PO 4 and (La,Gd)PO 4, to obtain good agreement between the calculated lanthanides ratio Nd/Gd and ratios estimated from XRD and EDS measurements.