Presence Of Sn2 Research Articles

Synthesis, Characterization and Photocatalytic Activity of Ag+ - and Sn2+ -Doped KTi0.5 Te1.5 O6.

In this study, the photocatalytic dye degradation efficiency of KTi0.5 Te1.5 O6 synthesized through solid-state method was enhanced by cation (Ag+ /Sn+2 ) doping at potassium site via ion exchange method. As prepared materials were characterized by XRD, SEM-EDS, IR, TGA and UV-Vis Diffuse reflectance spectroscopic (DRS) techniques. All the compounds were crystallized in cubic lattice with Fd3¯m space group. The bandgap energies of parent, Ag+ - and Sn+2 -doped KTi0.5 Te1.5 O6 materials obtained from DRS profiles were found to be 2.96, 2.55 and 2.40eV, respectively. Photocatalytic efficiency of parent, Ag+ - and Sn+2 -doped materials was evaluated against the degradation of methylene blue (MB) and methyl violet (MV) dyes under visible light irradiation. The Sn+2 -doped KTi0.5 Te1.5 O6 showed higher activity toward the degradation of both MB and MV dyes and its higher activity is ascribed to the lower bandgap energy compared to the parent and Ag+ -doped KTi0.5 Te1.5 O6 . The mechanistic degradation pathway of methylene blue (MB) was studied in the presence of Sn2+ -doped KTi0.5 Te1.5 O6 . Quenching experiments were performed to know the participation of holes, super oxide and hydroxyl radicals in the dye degradation process. The stability and reusability of the catalysts were studied.

A through bond energy transfer based ratiometric probe for fluorescent imaging of Sn2+ ions in living cells

A 4-(naphthalen-1-ylethynyl) aniline appended rhodamine based fluorescent chemosensor ‘NAP-RD’ is synthesized which undergoes through bond energy transfer in the presence of Sn2+ ions in mixed aqueous media.

Electrodeposition of Ni–Co–Sn alloy from choline chloride-based deep eutectic solvent and characterization as cathode for hydrogen evolution in alkaline solution

The electrodeposition of Ni–Co–Sn alloy were carried out at room temperature from the chlorine chloride (ChCl)–ethylene glycol (EG) deep eutectic solvent (DES). For comparison of properties, Ni–Sn and Co–Sn alloys were also deposited using the same solvent. Deposition mechanism, microstructure, and electrochemical properties of the deposits in 1 M KOH solution were investigated. The deposition of Ni, Co, Sn, Ni–Sn, Co–Sn and Ni–Co–Sn on platinum electrode were also studied using cyclic voltammetry. Interestingly, the electrochemical stability of DES is observed to be increased in the presence of Sn2+ ions. The X-ray diffraction (XRD) patterns showed only Ni phases indicating that the other elements get incorporated inside the nickel matrix and the lattice constant have linear relation with Sn content in alloy. The morphologies of Ni–Sn and Ni–Co–Sn alloys were observed to be almost same with fine grains, the XRD studies confirm this. The potentiodynamic polarization measurements showed that the Ni–Co–Sn alloy exhibits the lowest corrosion current density (jcorr), noblest corrosion potential (Ecorr) and highest exchange current density (jc) value than the other two binary alloys, indicating that the ternary alloy is a good candidate for Hydrogen Evolution Reaction (HER).

Immobilization of Cauliflower Myrosinase on Agar Agar Matrix and its Application with Various Effectors

The purified and thermo stable myrosinase from cauliflower seedlings was immobilized by 3.5% agar agar matrix and immobilized myrosinase chips were stored in extraction buffer. After 48 hours 30% enzyme activity was exuded into extraction media from immobilized enzyme chips. Effect of some metal ions and organic solvents on the activity of immobilized cauliflower myrosinase was studied. Amongst selective metal ions (Sr2+, Sn2+ and Ba2+), Sr2+ at 4 mM concentration exhibited marked activating effect on the activity up to 3 fold. However, Sn2+ and Ba2+ increased the activity to a certain extent and then suppressed. Activation kinetics of myrosinase in presence of Sn2+ and Sr2+ were studied between 0-20min.The rate of reaction was almost constant till 15 min and then slight deactivation was recorded at various concentrations used. On the other hand, few heavy metal ions [Fe2+, Fe3+, Cu2+ and Zn2+] strongly inhibited the activity even at lower concentrations. Several nonpolar organic solvents even at comparatively higher concentrations had detectable activation effects. Further, their activity was seen with respect totime (27 min). However, some protic polar organic solvents exhibited inhibitory effect with immobilized myrosinase except to butanol.

Preparation of monodisperse polystyrene/silver composite microspheres and their catalytic properties

This article presents a facile method for the preparation of polystyrene/silver (PS/Ag) composite microspheres. In this approach, monodisperse PS spheres were synthesized via dispersion polymerization and modified by sulfonation to obtain sulfonated PS spheres with sulfonic acid groups on the surfaces, and then adsorbed Sn2+ ions by electrostatic interaction and used as templates. PS/Ag composite microspheres were prepared successively by addition of [Ag(NH3)2]+ complex ions to the templates dispersion, adsorbing to the surfaces of templates, and then reduction of [Ag(NH3)2]+ complex ions to Ag nanoparticles by sodium potassium tartrate. The results showed that monodisperse PS spheres with sulfonic acid groups on the surfaces were coated by an incomplete and nonuniform coverage of Ag nanoparticles in the absence of Sn2+ ions. In the presence of Sn2+ ions, however, complete and uniform Ag nanoparticles coatings were obtained on the entire PS sphere. And the deposition density and size of Ag nanoparticles can be controlled by [Ag(NH3)2]+ concentration. The resulting PS/Ag composite microspheres were characterized by SEM, TEM, XRD, TGA, and UV-vis. Preliminary catalytical tests indicated these PS/Ag composite microspheres showed good catalytic properties.

Quench and Recovery Characteristics of Solid Nitrogen (SN2) Cooled YBCO Coated Conductor (CC) Tapes with Different Stabilizers

Recently, a cooling system using solid nitrogen (SN2) as a cryogen was suggested to enhance the thermal and electrical stabilities of high temperature superconductor (HTS) magnet applications, due to its large heat capacity. For the successful application of the SN2 cooling system to HTS devices, it is necessary to obtain sufficient data about the thermal and electrical characteristics of the SN2-cooled YBCO coated conductor (CC). Therefore, this study examined the thermal and electrical properties of YBCO CC tapes with different stabilizers in the presence and absence of SN2. The results clearly showed that the thermal and electrical stabilities of the YBCO CC tapes were drastically improved in the presence of the SN2, regardless of the stabilizer materials. Furthermore, copper was found to be more suitable as a stabilizer of YBCO CC tape in the SN2 cooling system than stainless steel.

Crossed-discs of mesoporous silica SBA-15 and their carbon replicas

Crossed-discs of mesoporous silica SBA-15 were synthesized by using tetramethylorthosilicate (TMOS) as silica source in the presence of Sn2+ cations. The silica crossed-discs were characterized by small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption. All the results show that the materials have hexagonally ordered channels running parallel to the thickness of the discs. The effects of the reaction conditions on the morphology of the materials were discussed. The SBA-15 crossed-discs were used as hard templatesto obtain their carbon replicas.

Tin(II) Doped Anatase (TiO2) Nanoparticles: A Potential Route to “Greener” Yellow Pigments

During our exploration of compounds in the Sn(II)-Ti(IV)-O system, we discovered that hydrolysis of titanium alkoxide solution in the presence of Sn(II) salts resulted in stable deep-yellow colored anatase nanoparticles. The samples were characterized by X-ray powder diffraction, electron microprobe, thermal analysis, transmission electron microscopy, and (119)Sn Mössbauer spectroscopy. Mössbauer data of the yellow colored samples showed the presence of both Sn(II) and Sn(IV) in a distorted environment as expected in the anatase structure. It is suggested that the cationic charge imbalance is compensated by oxygen vacancies and/or hydroxyl groups as evidenced by Mössbauer data which show two types of Sn(II) environments. When heated in air to 300 degrees C the samples changed color to completely white and (119)Sn Mössbauer data of these samples showed only the presence of Sn(IV). These observations indicate that the origin of the yellow color in our Sn doped anatase nanoparticles arises from filled Sn 5s states just above the O 2p band, thus decreasing the band gap. The Sn(II) doped anatase TiO(2) nanoparticles reported here can potentially lead to environmentally benign yellow pigments. The simplistic nature of the synthetic procedure could easily be adapted to large-scale industrial manufacture.

Preparation of a Reduced Layered Tungstic Acid HxW2O7 via Acid Treatment of Bi2W2O9 in the Presence of Sn2+ Ions

ABSTRACTA reduced layered tungstic acid with a double-octahedral structure was prepared by acid treatment of an Aurivillius-type Bi2W2O9 in the presence of Sn2+ ions. While the color of the product formed by acid treatment with no Sn2+ ions present, H2W2O7, was yellow, a blue powder was obtained after the acid treatment in the presence of Sn2+ ions. No notable change in the morphology was observed after acid treatment. The X-ray diffraction pattern of the product acid-treated in the presence of Sn2+ ions was very similar to that of H2W2O7. Essentially all the Bi3+ ions were lost upon acid treatment, indicating the occurrence of selective leaching of bismuth oxide sheets in Bi2W2O9. A UV-visible absorption spectrum and XPS analysis demonstrated that the W6+ ions were partially reduced to W5+ ions, and the number of protons in the product was correspondingly 2.4 per [W2O7]. These results suggest the successful formation of a reduced layered tungstic acid, H2.4W2O7.

Optical, structural and electrical properties of Mn doped tin oxide thin films

Mn doped SnOx thin films have been fabricated by extended annealing of Mn/SnO2 bilayers at 200°C in air for 110 h. The dopant concentration was varied by controlling the thickness of the metal layer. The overall thickness of the film was 115 nm with dopant concentration between 0 and 30 wt% of Mn. The films exhibit nanocrystalline size (10-20 nm) and presence of both SnO and SnO2. The highest transmission observed in the films was 75% and the band gap varied between 2.7 and 3.4 eV. Significantly, it was observed that at a dopant concentration of ∼4 wt% the transmission in the films reached a minimum accompanied by a decrease in the optical band gap. At the same value of dopant concentration the resistivity also reached a peak. This behaviour appears to be a consequence of valence fluctuation in Sn between the 2+ and 4+ states. The transparent conductivity behaviour fits into a model that attributes it to the presence of Sn interstitials rather than oxygen vacancies alone in the presence of Sn2 +.

NATURAL PYRRHOTITE DISSOLUTION IN AQUEOUS SOLUTION

The effects of some metal (II) ions on the natural pyrrhotite dissolution in hydrochloric acid solutions were studied Our results suggest that the rate of pyrrhotite dissolution increases in the presence of Sn2+ ion. Ions like Ni2+, Co2+, Cu2+, zn2+ do not appear to have any effect on pyrrhotite dissolution in hydrochloric acid solutions. The magnitude of the activation energy (23.31 kJ mol-1) is in agreement with a mechanism controlled by a diffusion process.

Preparation of99mTc-N2S2 conjugates of chrysamine G, potential probes for the beta-amyloid protein of Alzheimer's disease

Chrysamine G is known to bind in vitro to the β-amyloid protein (Aβ 10–43) and to homogenates of several regions of brain of Alzheimer's patients. The purpose of this study was to develop a 99mTc-labelled derivative of chrysamine G, in which the structural requirements of β-amyloid affinity are preserved. Bis-S-trityl protected monoamide-monoaminedithiol (MAMA-Tr2, a chelating system used to incorporate 99mTc, was coupled with 2-(chloroacetylamino)-chrysamine G diethyl ester (4) yielding 2-(MAMA-Tr2-acetylamino)-chrysamine G diethyl ester (5-Tr2). To prepare 4, 4,4′-dinitro-2-biphenylamine was treated with chloroacetyl chloride to obtain 2-(chloroacetylamino)-4,4′-dinitrobiphenyl, of which the nitro functions were reduced by catalytic hydrogenation. Diazotation of 2-(chloroacetylamino)-4,4′-diaminobiphenyl, followed by coupling with ethyl salicylate provided 4 in an overall yield of 4.3%. Alkaline hydrolysis of 5-Tr2 resulted in the monoethyl ester derivative (6-Tr2) and diacid derivative (7-Tr2). Detritylation and labelling with 99mTc was performed in the presence of Sn2+ and 99mTcO4− solution at pH 2–3 with heating. RP-HPLC analysis showed one peak for both the diester derivative (99mTc-5) and the diacid derivative (99mTc-7), while two peaks (A and B) were present for the monoethyl ester derivative (99mTc-6), probably isomers with respect to the ester position. The order of elution from RP-HPLC reflected the lipophilicity of the 99mTc-complexes as determined by partitioning between 1-octanol and phosphate buffer pH 7.4 (log P: 99mTc-5=2.15, 99mTc-6A=1.79, 99mTc-6B=1.93, 99mTc-7=1.08). Copyright © 1999 John Wiley & Sons, Ltd.

The texture–surface morphology relationship in zinc–iron electrolytic coatings

A combination of X-ray texture measurements and atomic force microscopy topographical analysis was used to characterize the growth surface of Zn–Fe alloys electrolytically deposited on cold rolled steel substrates. Deposits, which initially exhibited a morphology of approximately 20 nm thick platelets inclined 10°–20° to the substrate surface, subsequently evolved either into triangular pyramids or hexagonal columnar crystals depending on the presence of Sn2+ ions in the sulphate electrolyte. The morphology of the triangular pyramids, formed in the absence of Sn2+ ions, had (1 0 · 0) and (0 0 · 1) planes of η (hcp) phase tilted to the substrate surface. For the morphology of hexagonal columnar crystals, formed in the presence of Sn2+ ions, the (0 0 · 1) basal planes of η phase were aligned parallel to the substrate surface. The macro and nano-size steps of growth were identified on both morphologies in order to locate the active growth front. It is concluded that the lateral growth on the same (0 0 · 1) basal planes of η phase led to the formation of essentially different morphologies and textures of the Zn–Fe deposits. © 1998 Chapman & Hall

One-Pot Procedure for Producing Allene Carboxylic Esters from BHT Esters

Various methyl allenecarboxylates were efficiently prepared from the corresponding BHT esters in a one-flask procedure which consisted the in situ generation of the ketene from the BHT ester and the successive HWE reaction with trimethyl phosphonoacetate anion in the presence of Sn2+ or Zn2+ cation.

臭化亜鉛溶液における亜鉛の電析および溶解におよぼす添加剤の影響

The effect of inorganic and organic additives on the electrodeposition or electrodissolution of zinc in aqueous zinc bromide solution has been studied by the faradaic impedance method. The reaction velocity for zinc decreased when additives were used, but the rate-determining step in the process of zinc deposition was scarcely influenced. The characteristics of the charging-discharging cycle was found to be much improved by the presence of Sn2+ ion in the bath.It was confirmed that the oxide film on the anode is removed by the reduction of Sn2+ ion.

Interstitial Sn2+ in synthetic and natural cassiterite crystals

Evidence for the presence of Sn2+ in an octahedral interstitial site in synthetic and natural cassiterite (SnO2) is presented. The absorption and relative absorption spectral peaks measured are similar to ones found in Sn2+-doped KI by absorption spectrophotometry and Sn2+-doped soda-silica glass by reflection spectroscopy. The estimated quantity of interstitial Sn2+ present is found by calculating that needed to balance the uncompensated M3+ impurity in substitutional Sn4+ sites where M3+ is mainly Al3+ and Fe3+. Estimates of the oscillator strengths of three Sn2+ bands detected by absorption spectrophotometry in the synthetic crystal are given. The interstitial Sn2+ content in synthetic and natural cassiterite is not affected by heating,60Co gamma irradiation, or UV light treatment with a high pressure xenon-mercury lamp.