Extraction-photometric determination of vanadium(V) with N-hydroxy-N-m-tolyl-N′-(2-methyl-5-chloro)phenyl-p-toluamidine hydrochloride in the presence of acetic,monochloroacetic, and phenylacetic acids

N-Hydroxy-N-m-tolyl-N′-(2-methyl-5-chloro)phenyl-p-toluamidine hydrochloride (HTMCPTH), a monobasic and bidentate chelating agent which reacts with vanadium(V) in carboxylic acid media to develop a blue-violet complex, has been employed as a highly selective reagent for extraction and direct photometric determination of the metal. Solvent extraction experiments indicate that from aqueous acetic acid (1.0–10.0 M), monochloroacetic acid (0.1–10.0 M), and phenylacetic acid (at pH 0.5–6.0) vanadium(V) is quantitatively extracted into chloroform. Almost all common ions including Fe³⁺, Cu²⁺, Ni²⁺, Co²⁺, Mn²⁺, Cr³⁺, Ti⁴⁺, Zr⁴⁺, and Mo⁶⁺ do not interfere with the proposed method. The procedure has been utilized for accurate determination of vanadium in standard steels.     

Surface tension measurements in the study of molecular complexes

Surface tension measurements can be used to investigate molecular complex formation in liquid solutions for strong and weak complexes. The association constant and epthalpy for triethylamine-iodine, hexamethylbenzene-tetracyanoethylene and ethanol-iodine in cyclohexane are 4·55×10³, 218 and 0.93M⁻¹ at 25° C and 12·5, 7·7 and 5·1 kcal/mol respectively. These values compare well with those reported in the literature by other methods.     

Fenugreek mucilage as a flocculating agent for sewage treatment

The use of fenugreek mucilage, a natural polysaccharide and a direct food additive, as a flocculating agent for removal of suspended and dissolved solids from sewage effluent has been reported. A flocculation study has been done by the standard jar test method. The percent removal of suspended solid (SS) and dissolved solid (TDS) was determined by varying the polymer dose, pH and contact time. X-ray diffraction patterns of the solid waste material of mucilage and flocs (so obtained after treatment) were used to suggest the incorporation of the crystalline waste material in the mucilage. The optimal mucilage concentration was found to be 0.16 mg/l. The suitable pH range for maximum solid removal (SS and TDS) was alkaline and the time required for treatment was 1-3 h.     

Thermodynamic stability of CaThF6(cr) by transpiration and e.m.f. techniques

In the present paper, we report the standard molar Gibbs energy of formation for CaThF₆ measured by gas equilibration and e.m.f. methods. The HF(g) vapour pressure over the equilibrium reaction: \({\text{CaThF}}_{6} \left( {\text{cr}} \right) + 2 {\text{H}}_{ 2} {\text{O}}\left( {\text{g}} \right) = {\text{CaF}}_{2} \left( {\text{cr}} \right) + {\text{ThO}}_{2} \left( {\text{cr}} \right) + 4{\text{HF}}\left( {\text{g}} \right)\) has been measured using transpiration technique. The above reaction mechanism has been established employing TG and XRD techniques. A fluoride e.m.f. cell: (−)Pt, CaF₂(cr) + ThOF₂(cr) + CaThF₆(cr) |CaF₂(cr)| NiO(cr) + NiF₂(cr), Pt(+) has been constructed to measure Gibbs energy of formation of CaThF₆ (cr) using CaF₂ (cr) as a solid electrolyte. The isobaric heat capacity \({\text{Cp}}_{\text{m}}^{{\circ }} \left( T \right)\) of the compound has been measured using differential scanning calorimetric technique. Based on the experimental results, thermodynamic functions for CaThF₆ have been generated.

     

Chemical effects of neutron induced nuclear reactions in KIO4 at different pH of dissolution

Dissolution effect on recoil¹²⁸I retention in the form of IO ₄ ^– ion following /n,/ process in potassium periodate target has been studied. A remarkable variation in retention is found both in solid and solution phase with the pH of dissolution. A suitable mechanism is suggested to explain the observed results.     

Linear free energy relationship of the energy of the CTTS transition of Halide ions with the solvatochromic parameter α

A linear free energy relationship was found betweenv _max, the energy of the absorption maximum of chloride, bromide, or iodide ion in various solvents, and the solvatochromic parameter which is a measure of the hydrogen bond donor ability of the solvent. The relationships are: for chloride,v _max=6.99+50.16 kK; for bromide,v _max=5.52+45.20 kK; for iodide,v _max=5.02+40.33 kK. The correlation ofv _max for iodide ion with gave a larger correlation coefficient and smaller standard deviation than a correlation with the E _T (30) parameter of Dimroth. From the values ofv _max for iodide ion and the solvated electron in liquid ammonia at 25°C, these correlations indicate a preliminary value of 0.00 for the parameter of liquid ammonia. This had not been reported before and is lower than expected from a general knowledge of the physical and chemical properties of liquid ammonia but is consistent with a more detailed consideration and recent gas phase measurements of hydrogen bond donor strength.     

Cation Exchange and Sorption Properties of TIN(IV) Phosphate

The ion exchange and sorption properties of crystalline Tin bis(monohydrogen orthophosphate) monohydrate of composition Sn(HPO(4))(2).H(2)O were studied in an aqueous solution of KCl over the temperature range 300-320 K, varying the pH and metal ion concentration in the solution. The data were explained on the basis of the law of chemical equilibrium. The metal ion sorption data were fitted to the Langmuir adsorption equation to evaluate the Langmuir parameters. The extent of adsorption was found to increase with an increase in temperature and metal ion concentration in the selectivity order Cu(2+)>Co(2+)>Ni(2+). The Langmuir parameters were used to calculate the thermodynamic functions like standard entropy, enthalpy, and free energy changes during the process of sorption. Copyright 2000 Academic Press.     

Biomaterials in total joint replacement

The current state of materials systems used in total hip replacement is presented in this paper. An overview of the various material systems used in total hip replacement reported in literature is presented in this paper. Metals, polymers, ceramics and composites are used in the design of the different components of hip replacement implants. The merits and demerits of these material systems are evaluated in the context of mechanical properties most suitable for total joint replacement such as a hip implant. Current research on advanced polymeric nanocomposites and biomimetic composites as novel materials systems for bone replacement is also discussed. This paper examines the current research in the materials science and the critical issues and challenges in these materials systems that require further research before application in biomedical industry.     

A single amino acid Gly-tag enables metal-free protein purification

Analytically pure proteins are indispensable for diverse applications, including therapeutics. Here, we report a methodology where a single amino acid, glycine, enables metal-free protein purification. This robust platform is enabled by a Gly-tag resin for site-specific capture, enrichment, and release through chemically triggered C–C bond dissociation by resonance-assisted electron density polarization.

Gly-tag resin precisely captures and releases a protein with one glycine at the N-terminus. The user-friendly protocol delivers analytically pure protein free of metal contaminants.     

Photopolymerization initiated by charge-transfer complex. I. Photopolymerization of methylmethacrylate with the use of quinaldine-bromine and lutidine–bromine charge-transfer complexes as photoinitiator

Photopolymerization of MMA was carried out with quinaldine–bromine (QN–Br₂) and lutidine–bromine (LU–Br₂) charge-transfer complexes as initiators. The rate of polymerization R_p increased with rising monomer concentration and the monomer exponent was computed as unity. At first the rate of polymerization accelerated and then reduced as the initiator concentration was increased. The initiator exponent was 0.5. The reaction was carried out at three different temperatures and overall activation energy was calculated at 4.0 kcal/mol. The kinetic data and other evidence indicate that the overall polymerization takes place in a radical mechanism. A suitable mechanism is suggested.