Total Amount Of Aluminum Research Articles

Determination of total and extractable amount of aluminum, copper, zinc, and lead in surgical suture threads by electrothermal atomic absorption spectrometry

Polymer-based materials such as surgical suture threads are the most important raw materials used in the manufacturing of medical devices. Determination of metal contamination in industrial surgical threads such as absorbable polydioxanone (PDO) and polyglycolic acid (PGA), and nonabsorbable polypropylene (PP) is very important for human health. Concentrations of aluminum, copper, zinc, and lead released from these surgical suture samples into various solutions were determined. The effects of parameters such as solvent type, temperature, pH of solvent, and time for release of these metals from the samples were investigated to determine optimum conditions. The extractable and total amount of aluminum, copper, zinc, and lead in PDO, PGA, and PP samples were performed by using electrothermal atomic absorption spectrometry. The aluminum, copper, zinc, and lead in certified standard material solution (IQC-026 mixture) were determined for the accuracy of the method. Limits of detection and quantification values of analytes found were 2.8 and 9.3 µg L−1 for aluminum, 1.5 and 5.0 µg L−1 for copper, 1.5 and 5.0 µg L−1 for zinc, and 2.9 and 9.7 µg L−1 for lead, respectively.

REDUCING THE CONTENT OF NONMETALLIC INCLUSIONS IN STEEL FOR PLATES

The content of nonmetallic inclusions in steel is one of the primary indicators of the quality of the finished product. Customers’ requirements on the overally quality of steel and on its nonmetallic inclusion content in particular have become more stringent. For example, products must conform to class 2‐3 under standard SEL072, class 0‐1 under standard GOST 22727, and class A under standard EN 160-85. To improve the quality of its flat-rolled products and retain its market reputation for high-quality steel alloyed with niobium, vanadium, chromium, nickel, molybdenum, and boron in different combinations, as well as for products destined for the domestic market (skelp for high-pressure gas-line pipe, plates and slabs for deep-sea drilling platforms, structural and bridge steel, ship plate, and high-strength boiler steel), the combine has had its specialists devise an integrated technology for obtaining continuous-cast semifinished products that keeps nonmetallic inclusions to a minimum. Stabilizing the carbon content of the steel within certain limits is the main way to lower the state of oxidation of the steel and prevent its contamination by nonmetallic inclusions. To this end, we modified the operating and design parameters of the nozzle block in the oxygen lances. This improved the blowing and slag-formation regimes in the converter process and stabilized carbon content at the sampling point (the carbon content now goes no lower than 0.05%), which in turn has allowed better control over the steelmaking operation as a whole. The quality of the deoxidizers used for the steel in large part determines the extent to which the steel will be contaminated by nonmetallic inclusions. The replacement of recycled aluminum of grade AV87 by primary aluminum reduced the amount of nonferrous-metal impurities that entered the steel. Those impurities tend to form low-melting eutectics along the boundaries of the dendrites during crystallization. The presence of these eutectics significantly weakens the boundaries in the cast steel and in the rolled product and ultimately increases the number of products rejected for defects during ultrasonic inspection. Blowing the entire melt with argon in the ladle with the use of a submersible lance creates the conditions necessary for the nonmetallic inclusions to be transferrd from the liquid metal to the slag and subsequently assimilated by the slag phase. When aluminum wire rod was added to the ladle instead of pig aluminum to correct the steel’s aluminum content, the degree of assimilation of this element increased from 45‐50% to 70‐75% and the total amount of aluminum used on the finishing unit decreased while the aluminum content of the finished steel remained stable (0.027‐0.035% Al). This ensured adequate deoxidation of the steel and attainment of the required set of mechanical properties. The reduction in aluminum consumption also decreases the degree of contamination of the steel by inclusions of alumina. The treatment of steel with calcium-silicon is known to improve the ductility properties of the rolled product. We increased the consumption of calcium-silicon of grade SK-25 or SK-30 to 1.5‐2.5 kg/ton steel by injecting it in a carrier gas (argon). In a variant, we also increased the consumption of calcium-silicon to 1.1‐1.6 kg/ton by introducing cored wire which

Effect of composition on the glass-forming tendency of barium aluminosilicate gels derived from metal alkoxides

The effect of composition on the glass-forming tendency of barium aluminosilicate gels derived from metal alkoxides with compositions near the theoretical composition of barium feldspar was studied. Results indicated that, in the experimental range, larger SiO 2 content and larger BaO/Al 2O 3 ratio were advantageous to glass formation. A criterion for glass formation in the studied system was established as ( b+3−4 y)/(2 y+ s(1+ b)/(100− s))< J c, where b is the BaO/Al 2O 3 ratio, s the mol percentage of SiO 2, y the fraction of four-coordinated aluminum over the total amount of aluminum, and J c is a constant for a definite experimental condition. The criterion showed good fitness with the experimental results.

Hypophosphatemia Induced by Dietary Aluminium Hydroxide Supplementation in Pigs: Effects on growth, blood variables, organ weights and renal morphology

Twenty-four pigs, 13-14 weeks of age, were studied during an experimental period of 10 weeks. The pigs were randomly divided into 3 groups. Two groups were fed a commercial feed supplemented either with a suspension of aluminium hydroxide (Al(OH)3) or aluminium phosphate (A1PO4). The third group served as a control. The same total amount of aluminium was given to each of the 2 experimental groups. After three weeks the Al(OH)3-pigs developed severe hypophosphatemia, with an average decrease in serum phosphate of 60%, a decreased growth rate and a lower concentration of 2,3-diphosphoglycerate in the erythrocytes as compared to controls. Intense hypercalcemia developed in the Al(OH)3-group during the first 6 weeks, whereas the AlPO4-pigs and the control group developed neither hypophosphatemia nor hypercalcemia. At necropsy, the consequence of the long lasting hypophosphatemia was found to be increased relative kidney weights with morphological signs of tubular damage and dyscalcification. No similar changes were observed in the AlPO4-groups and there were no organ weight deviations compared to the control group.

Alternative phosphate binders in dialysis patients: calcium carbonate.

Traditionally, phosphate binders containing aluminum have been used effectively to control serum phosphorus levels in patients with chronic renal failure. In these patients, however, absorption and accumulation of aluminum in plasma and tissues can lead to debilitating pathologic conditions, including aluminum-related osteodystrophy. An alternative therapeutic approach using calcium carbonate as a phosphate binder has been proven to be effective. In a recent study of 20 patients on chronic hemodialysis, the efficacy of calcium carbonate therapy was demonstrated. Serum phosphorus levels in these patients were 4.8 +/- 0.13 mg/dL with the use of aluminum-containing phosphate binders, 7.3 +/- 0.26 mg/dL when phosphate binders were discontinued, and 4.8 +/- 0.17 mg/dL with the use of calcium carbonate (Os-CaL 500) therapy. The total amount of aluminum ingested for all 20 patients combined went from 112 g/d at the beginning of the study to 22 g/d at the end of the study. The amounts of calcium carbonate administered varied because of large variations in dietary phosphorus intake between patients. In addition, the individual distribution of phosphorus intake during the day dictated the dosing schedule. There were no adverse side effects associated with calcium carbonate therapy. A few patients ingesting large amounts of calcium carbonate to control their extremely high phosphorus levels developed hypercalcemia. However, this effect was reversible after discontinuation of calcium carbonate therapy.

Immunogenicity of purified Habu snake-venom toxoid in guinea pigs and monkeys with special reference to HR1 component.

Purity of the parent toxin influenced greatly the immunogenicity in guinea pigs of HR1 component of Habu-venom toxoid. The potency of HR1 toxoid in terms of the immunizing unit (ImU) appeared to be related to the antigen and aluminum contents. The immune response of the animals differed depending on the purity of the toxoid when the dose-response curve was examined over a wide range of the antigen dosage. Anti-HR1 titers of the guinea pigs immunized with crude toxoid (adsorbed) reached a plateau at about 10-20 U/ml ane further rise was not remarkable even when the amout of the antigen was increased several times, while 200 U/ml (maximum 400 U/ml or higher) of annti-HR1 was produced with a large amount of highly purified HR1 toxoid. Purified toxoid showed an excellent immunogenicity also in monkeys. The amounts of antigens necessary for the basic immunization to resist the challenge with a certainly lethal dose of crude venom were 18 and 0.5 mg as protein, for a crude and a highly purified toxoid, respectively. The total amount of aluminum was also reduced from 8.1 (crude toxoid) to 0.5 mg (purified toxoid). Multiple injections for the primary immunization enhanced early production of anti-HR1 in monkeys. However, at later stage of immunization, significant correlation was observed between the amount of HR1 toxoid (in ImU) for the primary immunization and the circulating anti-HR1 titer irrespective of the schedule of immunization. Anti-HR2 higher than 10 U/ml was produced consistently in monkeys with HR2 toxoid of 1.0 ImU for the basic immunization. However, excess HR2 toxoid of more than 10 ImU seemed rather unfavorable for anti-HR2 production.

Analytical applications of condensed phosphoric acid—II Determination of aluminium, iron and titanium in bauxites after decomposition with condensed phosphoric acid

Bauxites can be decomposed by condensed phosphoric acid (CPA) very rapidly without the need for subsequent manipulations such as elimination of silica, digestion of fused products and filtration. It is best to heat the samples at about 700° prior to the decomposition, to prevent them from floating on the surface of the CPA. Under the proposed conditions (100 mg of sample, 10 g of CPA, heating at 300° for 30 min), aluminium, iron and titanium are dissolved quantitatively. Iron is determined by photometry with 1,10-phenanthroline after solvent extraction with MIBK, while titanium is determined with N-benzoyl- N-phenylhydroxylamine (BPHA). The effect of phosphate on the determination of titanium is reduced to a minimum at a BPHA concentration of 0.3% and a hydrochloric acid concentration of 7.2 M. Aluminium and iron are precipitated quantitatively as the oxinates at pH 5.5 in the presence of orthophosphoric acid or hydrolysed CPA, while the precipitation of titanium oxinate is completely suppressed by the addition of hydrogen peroxide. The total amount of aluminium and iron is obtained by determining the amount of oxine by bromination method. The amount of aluminium is obtained by subtracting the amount of iron from the sum of the two.

Selectivity and Adsorption Capacity of Smectite and Vermiculite for Aluminum of Varying Basicity

AbstractSmectite (from South Dakota, Wyoming, and Mississippi) and Vermiculite (Transvaal) were treated with solutions of Al(OH)B(3-B)+, with B varying from 0 to 2.5. The average basicity (OH/Al = B) of the Al adsorbed differed very much from the basicity of the Al added. The average basicity of the Al adsorbed by smectite was always above the average basicity of the Al added. In contrast to smectite, Vermiculite adsorbed smaller hydroxy-Al complexes. One reason for the different selective behavior was the difference in expansion between smectite (about 18 Å) and vermiculite (about 14 Å). Because of the adsorption of the relatively more basic OH-Al by smectite, smectite adsorbed considerably more Al than vermiculite. The total amount of aluminum in the interlayer generally could not be calculated by the difference between Al added and that remaining in solution after the reaction because of possible protonation of the clay mineral and adsorption of structural Al and other cations, which is more pronounced for vermiculite. The results in the present study demonstrated that neither the quantitative nor the qualitative composition of an Al(OH)B-treated exchanger can be deduced from B of the Al salts added. These points are frequently overlooked when cation exchangers are pretreated with Al of variable basicity and are used for further investigations, such as studies of CEC, surface area, interlayer spacing, anion reactions, the formation of gibbsite, etc. Before these kinds of investigations are conducted employing the pretreated OH-Al-exchangers, their composition should be known precisely.