Development of stable extractive scintillating materials for real-time quantification of radiostrontium in aqueous solutions

Journal of Radioanalytical and Nuclear Chemistry - The research presented here is the development of sensor materials that are applicable for real-time in situ quantification of radiostrontium in...     

Functionalization of α-Aminonicotinonitrile: A New Entry for Synthesis of Pyrazolo[3,4-b]pyridine,Pyrido[2,3-d]pyrimidine,and 1,8-Naphthyridine Derivatives

Russian Journal of General Chemistry - Functionalization of α-aminopyridine to a new series of pyridine and fused pyridine derivatives has been achieved via its reaction with a variety of...     

On the Dot Product Graph of a Commutative Ring

Let A be a commutative ring with nonzero identity, 1 ≤ n < ∞ be an integer, and R = A × A × … ×A (n times). The total dot product graph of R is the (undirected) graph TD(R) with vertices R* = R?{(0, 0,…, 0)}, and two distinct vertices x and y are adjacent if and only if x·y = 0 ∈ A (where x·y denote the normal dot product of x and y). Let Z(R) denote the set of all zero-divisors of R. Then the zero-divisor dot product graph of R is the induced subgraph ZD(R) of TD(R) with vertices Z(R)* = Z(R)?{(0, 0,…, 0)}. It follows that each edge (path) of the classical zero-divisor graph Γ(R) is an edge (path) of ZD(R). We observe that if n = 1, then TD(R) is a disconnected graph and ZD(R) is identical to the well-known zero-divisor graph of R in the sense of Beck–Anderson–Livingston, and hence it is connected. In this paper, we study both graphs TD(R) and ZD(R). For a commutative ring A and n ≥ 3, we show that TD(R) (ZD(R)) is connected with diameter two (at most three) and with girth three. Among other things, for n ≥ 2, we show that ZD(R) is identical to the zero-divisor graph of R if and only if either n = 2 and A is an integral domain or R is ring-isomorphic to ?₂ × ?₂ × ?₂.     

Response Characteristics of Copper‐Selective Polymer Membrane Electrodes Based on a Newly Synthesized Macrocyclic Calix[4]arene Derivative as a Neutral Carrier Ionophore

A novel macrocyclic calix[4]arene derivative was examined as an ionophore for ion‐selective polymeric membrane electrode toward Cu⁺² ions. The sensor showed a near Nernstian response for Cu(II) ions over a concentration range from 8.1×10^?6 to 1.0×10^?2 mol L^?1 with a slope of 34.2±0.4 mV per concentration decade in an acidic solution (pH 5). The limit of detection was 0.47 µg mL^?1. It had a response time of <20 s and can be used for at least 3 months without any divergence in potentials. The influence of plasticizer as well as the amount of lipophilic anionic site additive in the sensing membrane was discussed. It was shown that membrane electrodes formulated with the ionophore and appropriate anionic additive exhibited enhanced potentiometric response toward Cu²⁺ over all other cations tested. Since selectivity toward Cu²⁺ ions is decreased in the presence of high amount of the anionic additive, the ionophore can function as neutral carriers within the organic membrane phase. Validation of the assay method revealed good performance characteristics, including long life span, good selectivity for Cu²⁺ ions over a wide variety of other metal ions, long term response stability, and high reproducibility. The sensors were used for direct measurement of copper content in different rocks collected from different geological zones. The results agreed fairly well with data obtained using atomic absorption spectrometry.     

Chromatographic separation of In(III) from Cd(II) in aqueous solutions using commercial resin (Dowex 50W-X8)

This work assesses the potential of an adsorptive material, Dowex 50w-x8, for the separation of indium ions from cadmium ions in aqueous media. The adsorption behavior of Dowex 50 w-x8 for indium and cadmium ions was investigated. The effect of pH, initial concentration of metal ions, the weight of resins, and contact time on the sorption of each of the metal ions were determined. It was found that the adsorption percentage of the indium ions was more than 99% at pH 4.0. The result shows that In (III) was most strongly extracted, while Cd(II) was slightly extracted at this pH value. The recovery of In(III) and Cd(II) ions is around 98% using hydrochloric acid as the best eluent.      

The direct determination of partial molar volumes and reaction volumes in ultra-dilute non-reactive and reactive multi-component systems using a combined spectroscopic and modified response surface model approach

Two experimental multi-component organometallic systems were studied, namely, (1) a non-reactive system consisting of [Mo(CO)(6)], [Mn(2)(CO)(10)], and [Re(2)(CO)(10)] in toluene under argon at 298.15 K and 0.1 MPa and (2) a reactive system consisting of [Rh(4)(CO)(12)] + PPh(3)--> [Rh(4)(CO)(11)PPh(3)] + CO in n-hexane under argon at 298.15 K and 0.1 MPa. The mole fractions of all solutes were less than 140 x 10(-6) in system (1) and less than 65 x 10(-6) in system (2). Simultaneous in-situ FTIR spectroscopic measurements and on-line oscillatory U-tube density measurements were performed on the multi-component solutions. A newly developed response surface methodology was applied to the data sets to determine the individual limiting partial molar volumes of all constituents present as well as the reaction volume. The limiting partial molar volumes obtained for system (1) were 176.4 +/- 2.5, 265.1 +/- 2.4, and 276.8 +/- 2.4 cm(3) mol(-1) for [Mo(CO)(6)], [Mn(2)(CO)(10)], and [Re(2)(CO)(10)], respectively and are consistent with independent binary experiments. The limiting partial molar volumes obtained for system (2) were 310.7 +/- 2.7, 219.8 +/- 2.2 and 461.5 +/- 4.5 cm(3) mol(-1) for [Rh(4)(CO)(12)], PPh(3) and [Rh(4)(CO)(11)PPh(3)], respectively. In addition, a reaction volume Delta(r)V equal to -17.0 +/- 5.7 cm(3) mol(-1) was obtained. The present results demonstrate that both partial molar volumes and reaction volumes can be obtained directly from multi-component organometallic solutions. This development provides a new tool for physico-chemical determinations relevant to a variety of solutes and their reactions.     

Indirect spectrophotometric determination of gentamicin and vancomycin antibiotics based on their oxidation by potassium permanganate

Four simple, accurate, sensitive and economical procedures (A–D) for the estimation of gentamicin sulphate and vancomycin hydrochloride, both in pure form and in pharmaceutical formulations have been developed. The methods are based on the oxidation of the studied drugs by a known excess of potassium permanganate in sulphuric acid medium and subsequent determination of unreacted oxidant by reacting it with amaranth dye (method A), acid orange II (method B), indigocarmine (method C) and methylene blue (method D), in the same acid medium at a suitable λ_max=521, 485, 610 and 664 nm, respectively. The reacted oxidant corresponds to the drug content. Regression analysis of Beer-Lambert plots showed good correlations in the concentration ranges 4–8, 3–8, 4–9 and 5–9 μg ml⁻¹ with gentamicin and 4–8, 1.5–4, 1.5–4 and 3.5–5.5 μg ml⁻¹ with vancomycin for methods A, B, C, and D, respectively. The molar absorptivity, sandell sensitivity, detection and quantification limits were calculated. The stoichiometric ratios for the cited drugs were studied. The optimum reaction conditions and other analytical parameters were evaluated. The influence of the substance commonly employed as excipients with these drugs were studied. The proposed methods were applied to the determination of these drugs in pharmaceutical formulations. The results have demonstrated that the methods are equally accurate and reproducible as the official methods.     

Lower Activation Energy for Catalytic Reactions through Host–Guest Cooperation within Metal–Organic Frameworks

Industrial synthesis is driven by a delicate balance of the value of the product against the cost of production. Catalysts are often employed to ensure product turnover is economically favorable by ensuring energy use is minimized. One method, which is gaining attention, involves cooperative catalytic systems. By inserting a flexible polymer into a metal–organic framework (MOF) host, the advantages of both components work synergistically to create a composite that efficiently fixes carbon dioxide to transform various epoxides into cyclic carbonates. The resulting material retains high yields under mild conditions with full reusability. By quantitatively studying the kinetic rates, the activation energy was calculated, for a physical mixture of the catalyst components to be about 50 % higher than that of the composite. Through the unification of two catalytically active components, a new opportunity opens up for the development of synergistic systems in multiple applications.     

Mercury(II) ion-selective polymeric membrane sensors for analysis of mercury in hazardous wastes.

Two novel potentiometric sensors that are highly selective to Hg2+ ions are described. These are based on the use of 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB) and tricyclazole (TCZ) as neutral carriers in plasticized poly(vinyl chloride) membranes. Fast Nernstian responses are obtained for Hg2+ ions over the concentration ranges 7.0 x 10(-6) - 1.0 x 10(-2) and 7.7 x 10(-6) - 1.0 x 10(-2) mol l(-1) at pH 1.8 - 3.3 with lower detection limits of 5.0 x 10(-6) and 5.6 x 10(-6) mol l(-1) (approximately 1 microh ml(-1)) and calibration slopes of 30.0 and 29.7 mV decade(-1) with DTNB- and TCZ-based membrane sensors, respectively. Validation of the assay method reveals good performance characteristics, including long life span, good selectivity for Hg2+ ions over a wide variety of other metal ions, long term response stability, and high reproducibility. Applications for direct determination of mercury in hazardous wastes including dental amalgam, mercury bulbs, and fluorescent lamps give results with good correlation with data obtained using cold vapor atomic absorption spectrometry.     

Spectrophotometric determination of manganese by using redox reaction of tris(2,2'-bipyridine)osmium(II) with Mn7+.

This paper reports on the analytical application of the oxidation reaction of [Os(bpy)3]2+ by Mn7+ (MnO4-). The present study developed a very simple, sensitive and selective spectrophotometric method for the determination of manganese in an acidic medium. Three analytical wavelengths were employed in the UV and visible regions at 290, 315 and 480 nm. Beer's law was obeyed up to a concentration of 330 ng ml(-1) of Mn7+ at different wavelengths with regression equations 0.001 - 0.0042C(Mn), 0.001 + 0.0021C(Mn), and 0.001 - 9.34 x 10(-4)C(Mn) at 290, 315 and 480 nm, respectively. Under the optimum conditions, the achieved detection limits were 0.72, 1.37 and 3.32 ng ml(-1) at 290, 315, and 480 nm, respectively. In addition to the high sensitivity of the method (0.24 ng cm(-2) at 290 nm, 0.45 ng cm(-2) at 315 nm and 1.0 ng cm(-2) at 480 nm), it can be used for the determination of manganese in the presence of a large number of anions and cations, since it tolerates most of the potential interferents. The relative standard deviation was 0.5% (n = 11) for 90 ng ml(-1) manganese. The method was successfully applied to the determination of manganese in water from different resources.