Distribution coefficients of tin in Japanese agricultural soils and the factors affecting tin sorption behavior

Sorption behavior of tin (Sn) in Japanese agricultural soils was studied. Soil-soil solution distribution coefficient (K(d)) of Sn (K(d)-Sn) for 142 soil samples ranged between 128 and 1,590,000 L kg(-1) with the geometric mean of 12 400 L kg(-1). The K(d)-Sn values for Andosol tended to be higher than those of the other soil groups. Among the relationships between K(d)-Sn values and soil properties, a high correlation was observed for soil active-Al (Al-(hydr)oxide and Al-humus complex) amount and K(d)-Sn. The pH effect on Sn sorption was also investigated. The results suggested that the low pH condition enhanced the Sn sorption in soils. The soil-sorbed Sn fractions in each type of soil material were also evaluated with selective extraction methods. The results showed that most of the soil-sorbed Sn was as organic matter bound or Al/Fe-(hydr)oxide-bound forms.

Dissolution of copper, tin, and iron from sintered tungsten-bronze spheres in a simulated avian gizzard, and an assessment of their potential toxicity to birds

The rates of dissolution of copper, tin, and iron from sintered tungsten-bronze spheres (51.1%W, 44.4%Cu, 3.9%Sn, 0.6%Fe, by mass) were measured in an in vitro simulated avian gizzard at pH 2.0, and 42C. Most of the spheres had disintegrated completely to a fine powder by day 14. Dissolution of copper, tin, and iron from the spheres was linear over time; all r>0.974; all P<0.001. The mean rate of release of copper, tin, and iron was 30.4 mg, 2.74 mg, and 0.38 mg per g tungsten-bronze per day, respectively. These rates of metal release were compared to those in published studies to determine whether the simultaneous ingestion of eight spheres of 3.48 mm diameter would pose a toxic risk to birds. The potential absorption rates of iron and tin (0.54 mg Fe/day, and 3.89 mg Sn/day) from eight tungsten-bronze spheres of total mass 1.42 g would not prove toxic, based on empirical studies of tin and iron ingestion in waterfowl. The release of 43.17 mg copper/day from eight tungsten-bronze spheres, while exceeding the daily copper requirements of domesticated birds, is far below the levels of copper known to cause copper toxicosis in birds. We conclude that sintered tungsten-bronze material made into gunshot, fishing weights, or wheel balance weights, would not pose a toxic risk to wild birds when ingested.

High power fiber laser driver for efficient EUV lithography source with tin-doped water droplet targets

In this paper we report the development of nanosecond-pulsed fiber laser technology for the next generation EUV lithography sources. The demonstrated fiber laser system incorporates large core fibers and arbitrary optical waveform generation, which enables achieving optimum intensities and other critical beam characteristics on a laser-plasma target. Experiment demonstrates efficient EUV generation with conversion efficiency of up to 2.07% for in-band 13.5-nm radiation using mass-limited Sn-doped droplet targets. This result opens a new technological path towards fiber laser based high power EUV sources for high-throughput lithography steppers.

Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, trimethylgermyl, trimethylstannyl, and trimethylplumbyl derivatives of 3,3-dimethylcyclopropene X. Some regularities

The changes in the vibrational frequencies of 1-tert-butyl and 1,2-di-tert-butyl derivatives of 3,3-dimethylcyclopropene brought about by substitution of the central carbon atom (X) of the tert-butyl moieties by Si, Ge, Sn, or Pb atoms are examined. The most important decrease in the vibrational frequencies implicating the X(CH(3))(3) moieties is noted for substitution of X=C by Si. The substitutions of Si by Ge or Ge by Sn or Sn by Pb are not accompanied by the pronounced frequency shifts observed for the C-->Si transition. An explanation is given for trends in these vibrational frequencies for the transitions X=C-->Si-->Ge-->Sn-->Pb. It is concluded that there are lower limiting values of the vibrational frequencies of a molecular moiety which are approached when the mass of its isovalent atom is increased. This leads to the formation of cluster regions in the vibrational spectra for the frequencies of the SnC(3) and PbC(3) moieties.

Phase-transition plasticity response in uniaxially compressed silicon nanospheres

We present a microscopic description for the response of crystalline Si nanospheres up to 10 nm in radius for various uniaxial compression levels. The behavior at low compressions closely resembles the Hertzian predictions. At higher compressions the creation of a new beta-tin phase in the particle core leads to (i) volumetric changes (ii) an increase in elastic moduli, and (iii) significant hardening. Further, (iv) a reversible character of the transformation is obtained with molecular dynamics simulations. The agreement of (i)-(iv) with recent experimental findings challenges the current exclusive view of a dislocation plasticity response in somewhat larger nanoparticles. The phase-transition path should dominate in ultrasmall structures, where dislocation activity is prohibited.

Preparation of re-usable photocatalytic filter for degradation of Malachite Green dye under UV and vis-irradiation

Sn(4+) doped and undoped nano-TiO(2) particles easily dispersed in water were synthesized without using organic solvent by hydrothermal process. Nanostructure-TiO(2) based thin films were prepared on flyswatter substrate, made with stainless steel, by dip-coating technique. The structure, surface and optical properties of the particles and thin films were characterized by element analysis and XRD, BET, SEM and UV/vis/NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that the coated flyswatter has a very high photocatalytic performance for the photodegradation of Malachite Green irradiated with UV and vis-lights. The results also proved that the hydrothermally synthesized nano-TiO(2) particles are fully anatase crystalline form and are easily dispersed in water, the coated surfaces are hydrophilic, and the doping of transition metal ion efficiently improved the degradation performance of TiO(2)-coated flyswatter. The photocatalytic performances determined at both irradiation conditions were very good and were almost similar to each other for Sn(4+) doped TiO(2)-coated flyswatter and it can be repeatedly used with increasing photocatalytic activity compared to undoped TiO(2)-coated flyswatter.

Synthetic, structural, mechanistic, and computational studies on single-site beta-diketiminate tin(II) initiators for the polymerization of rac-lactide

A family of tin(II) complexes supported by beta-diketiminate ligands has been investigated as initiators for the polymerization of rac-lactide. Kinetic studies reveal a first-order dependence on [lactide], but with a significant induction period. Linear plots of M(n) versus conversion and [M](o)/[I](o) versus conversion, along with narrow molecular weight distributions (typically 1.07-1.10), are indicative of well-controlled, "living" polymerizations. Less sterically hindered derivatives promote faster propagation than their bulky analogues, in accord with a more accessible active site. Enhanced rates of polymerization are observed for ligands bearing halogenated N-aryl substituents, a consequence of the more Lewis acidic nature of the Sn(II) centers. All of the initiators exhibit a similar bias toward heterotactic polylactide, which is attributed to a chain-end control mechanism influenced predominantly by the presence of the Sn 5s(2) lone pair of electrons rather than the steric or electronic properties of the beta-diketiminate ligand. The tin(II) isopropyl-(S)-lactate complex, ((Me)BDI(DIPP))SnOCH(Me)COO(i)Pr (14), has been synthesized as a model compound for the propagating species by treatment of ((Me)BDI(DIPP))Sn(NMe(2)) with isopropyl-(S)-lactate. An X-ray structure determination showed that the lactate ligand forms a five-membered chelate ring with a weak donor bond from the carbonyl oxygen atom to the tin center. A B3LYP density functional computational study indicates that insertion of the first lactide monomer into the tin(II) alkoxide bond is facile, with the induction period arising from a slower insertion of the second (and possibly third and fourth) monomer units.

Effect of Carbamide Peroxide Treatments on the Metal-ion Release and Microstructure of Different Dental Amalgams

Carbamide peroxide bleaching releases metal-ions from dental amalgam.

Interaction of tin(II) and arsenic(III) with DNA at the nanostructure film modified electrodes

Biosensors based on DNA and DNA-carbon nanotubes film immobilized at the surface of a screen-printed carbon electrode were used for simple in vitro tests of chemical toxicity. The damage to DNA caused by tin(II) and arsenic(III) compounds as components of specific reaction media was evaluated by means of an electrochemical DNA marker, [Co(phen)3](3+), as the portion of original dsDNA which survives an incubation of the biosensor in the cleavage medium. The results were confirmed by the electrically heated electrode and by the measurement of the DNA guanine moiety signal.

Micro-XRD study of beta–titanium wires and infrared soldered joints

OBJECTIVE

The purpose of this study was to investigate the metallurgical phases in beta-titanium soldered joints prepared by infrared soldering, using the Micro X-ray diffraction technique (Micro-XRD), and to characterize the Vickers hardness in the soldered beta-titanium wires.

METHODS

Beta-titanium wires with cross-section dimensions of 0.032in.x0.032in. (TMA, Ormco), and both titanium-based solder (Ti-30Ni-20Cu, Selec) and silver-based solder (Ag-22Cu-17Zn-5Sn, Tomy) were selected. Soldering was performed using infrared radiation (RS-1, Morita) under argon atmosphere. Micro-XRD analyses were performed at room temperature. Micro-XRD spectra were obtained for the boundary region of the soldered beta-titanium wires using 50microm and 10microm diameter analysis regions. Hardness was measured at 30microm intervals from boundary of the diffusion layer and beta-titanium wire. The Kruskal-Wallis test with the Bonferroni and Wilcoxson Mann-Whitney tests for nonparametric means were employed as statistical methods (P<0.05).

RESULTS

For both types of soldered beta-titanium samples, the Micro-XRD spectra contained four major peaks for body-centered cubic (bcc) beta-titanium. Additional peaks at about 41 and 45 degrees are attributed to Cu-Ti intermetallic phase(s), which may be metastable under soldering conditions. The diffusion layer had greater hardness than bulk beta-titanium for both types of soldered specimens (P<0.05).

SIGNIFICANCE

Soldering of beta-titanium orthodontic wire by infrared radiation may be acceptable for clinical use, since Micro-XRD spectra revealed that both types of soldered specimens largely retained the bcc beta-titanium structure. Further research is needed to investigate the mechanical properties and corrosion behavior of infrared-soldered beta-titanium wire.

Aqueous Barbier allylation of aldehydes mediated by tin

The aqueous tin-mediated Barbier reaction affords good to excellent yields and moderate syn diastereoselectivity under basic and acidic conditions. The high yields and stereoselectivity observed in the case of o-substituted aldehydes suggest a cyclic organotin intermediate or transition state in K2HPO4 solution. A practical and efficient aqueous tin allylation of methoxy- and hydroxybenzaldehydes can be carried out in HCl solution in 15 minutes to afford the corresponding homoallylic alcohols in high yields. Aliphatic aldehydes give moderate to excellent yields with reaction times ranging from 30 to 60 minutes. Under these conditions, crotylation gives exclusively the gamma-product and the syn isomer is formed preferentially. For 2-methoxybenzaldehyde, an equilibration of the isomers to a syn/anti ratio of 1:1 can be observed after several hours. Control experiments with radical sources or scavengers give no support for radical intermediates. NMR studies suggest a mechanism involving an organotin intermediate. The major organotin species formed depends on the reaction medium and the reaction time. The use of acidic solution reduces the reaction times, due to the acceleration of the formation of the allyltin(IV) species.

Gold-catalyzed 1,2-migration of silicon, tin, and germanium en route to C-2 substituted fused pyrrole-containing heterocycles

An efficient method for the synthesis of fused pyrroloheterocycles from diverse propargyl-substituted heterocycles in the presence of Au-catalyst has been developed. The cascade transformation proceeds via alkyne-vinylidene isomerization with concomitant 1,2-shift of hydrogen, silyl, and stannyl groups. Remarkably, it was also shown that previously unknown 1,2-migration of a germyl group upon alkyne-vinylidene rearrangement occurs under these reaction conditions. This method allows for mild and efficient synthesis of diverse C-2 substituted N-containing heterocycles.

Syntheses and characterization of organo-group 14 cobaloxime compounds

Reactions of cobaloxime Na[(t-BuPy)Co(DH)2] with Ph3ECl (E = Si, Ge, Sn, and Pb) were investigated. Metal-metal bonded complexes (t-BuPy)Co(DH)2EPh3 were isolated for E = Sn and Pb. (t-BuPy)Co(DH)2SnPh3.(C2H5)2O, C39H52CoN5O5Sn, crystallized in the monoclinic space group P21/c (Z = 4) with unit cell dimensions a = 11.6443(6) A, b = 15.6085(8) A, c = 22.6354(12) A, beta = 96.634(1) degrees , and V = 4086.4(4) A3 at 295(2) K. The structure resembled those of six-coordinate alkyl cobaloxime complexes and had Co-NPy and Co-Sn distances of 2.056(2) and 2.5568(3) A, respectively. (t-BuPy)Co(DH)2PbPh3, C35H42CoN5O4Pb, crystallized in the monoclinic space group P21/n (Z = 4) with unit cell dimensions a = 15.0104(7) A, b = 15.7693(8) A, c = 16.6230(8) A, beta = 114.348(1) degrees , and V = 3584.8(3) A3 at 295(2) K. The complex was nearly isostructural with the Sn analogue and had Co-NPy and Co-Pb distances of 2.049(2) and 2.6191(4) A, respectively. Coupling of the ortho phenyl protons to the spin 1/2 isotopes of Sn and of Pb was a characteristic feature of the 1H NMR spectrum. Additional, longer range couplings were observed for the Pb complex and for both complexes in the 13C NMR. Metal-metal bonded complexes were not obtained for E = Si or Ge. The products isolated in the latter case were the hydride Ph3GeH and the cobalt(II) complex (t-BuPy)Co(DH)2,C17H27CoN5O4, which crystallized in the orthorhombic space group Pbcn (Z = 8). Unit cell dimensions were a = 17.9821(11) A, b = 9.7449(6) A, c = 22.7374(15) A, and V = 3984.4(4) A3 at 295(2) K. The five-coordinate complex had Co-NPy = 2.096(2) A and was dimeric in the lattice.

[Preparation of particle-electrodes for treating phenol wastewater using three-dimensional electrolysis]

In order to effectively degrade phenol, various catalysts with different active metals, i.e. Cu, Zn, Ni, Ce, Fe, Co, Mn and Sn supported over gamma-Al2O3 used as three-dimensional electrodes were prepared by the incipient wetness impregnation. It is shown that, all particle-electrodes of single oxide and composite oxides could improve the degradation of phenol in varying degrees, and the single oxide and complex oxides of Mn and Sn could greatly improve electrochemical oxidation efficiency. When Mn and Sn ratio is 2 (molar fraction), the electrocatalytic activity is highest. Under current of 0.25 A, the conversion rate and total organic carbon (TOC) removal efficiency for model pollutant after 150 min treatment reach 90.8% and 80.7%, respectively. Electrocatalytic oxidation is further carried out in the presence of the *OH radical scavenger tert-butyl alcohol, which indicates that both direct and indirect oxidation are responsible for the degradation of phenol.

Ab initiocalculations on SnCl2 and Franck-Condon factor simulations of its ã-X̃ and B̃-X̃ absorption and single-vibronic-level emission spectra

Minimum-energy geometries, harmonic vibrational frequencies, and relative electronic energies of some low-lying singlet and triplet electronic states of stannous dichloride, SnCl(2), have been computed employing the complete-active-space self-consistent-field/multireference configuration interaction (CASSCF/MRCI) and/or restricted-spin coupled-cluster single-double plus perturbative triple excitations [RCCSD(T)] methods. The small core relativistic effective core potential, ECP28MDF, was used for Sn in these calculations, together with valence basis sets of up to augmented correlation-consistent polarized-valence quintuple-zeta (aug-cc-pV5Z) quality. Effects of outer core electron correlation on computed geometrical parameters have been investigated, and contributions of off-diagonal spin-orbit interaction to relative electronic energies have been calculated. In addition, RCCSD(T) or CASSCF/MRCI potential energy functions of the X(1)A(1), ã(3)B(1), and B(1)B(1) states of SnCl(2) have been computed and used to calculate anharmonic vibrational wave functions of these three electronic states. Franck-Condon factors between the X (1)A(1) state, and the ã (3)B(1) and B (1)B(1) states of SnCl(2), which include anharmonicity and Duschinsky rotation, were then computed, and used to simulate the ã-X and B-X absorption and corresponding single-vibronic-level emission spectra of SnCl(2) which are yet to be recorded. It is anticipated that these simulated spectra will assist spectroscopic identification of gaseous SnCl(2) in the laboratory and/or will be valuable in in situ monitoring of SnCl(2) in the chemical vapor deposition of SnO(2) thin films in the semiconductor gas sensor industry by laser induced fluorescence and/or ultraviolet absorption spectroscopy, when a chloride-containing tin compound, such as tin dichloride or dimethyldichlorotin, is used as the tin precursor.

Effects of In, Al and Sn dopants on the structural and optical properties of ZnO thin films

Effect of In, Al and Sn dopants on the optical and structural properties of ZnO thin films have been investigated by X-ray diffraction technique and optical characterization method. X-ray diffraction patterns confirm that the films have polycrystalline nature. The thin films have (002) as the preferred orientation. This (002) preferred orientation is due to the minimal surface energy which the hexagonal structure, c-plane to the ZnO crystallites, corresponds to the densest packed plane. The grain size values of the films are found to be 29.0, 35.2 and 39.5 nm for In, Al and Sn doped ZnO thin films, respectively. The optical band gaps of the films were calculated. The absorption edge shifts to the lower wavelengths with In, Al and Sn dopants. The inclusion of dopant into films expands also width of localized states as E(UIn)>E(UAl)>E(USn). The refractive index dispersion curves obey the single oscillator model. The dispersion parameters and optical constants of the films were determined. These parameters changed with In, Al and Sn dopants.

Chiral allylic and allenic metal reagents for organic synthesis

This account traces the evolution of our work on the synthesis of chiral allylic and allenic organometal compounds of tin, silicon, zinc, and indium and their application to natural product synthesis over the past quarter century.

Methylation mechanism of tin(II) by methylcobalamin in aquatic systems

The methylation reaction of tin(II) with methylcobalamin (CH(3)B(12)) in aquatic systems was modeled in the laboratory. The products were detected by a sensitive gas chromatography-flame photometric detector (GC-FPD), and further identified by gas chromatography-mass spectrometry (GC-MS). Both monomethyltin (MMT) and dimethyltin (DMT) were found as methylation products. Three important effecting factors during the methylation reaction, salinity, pH and aerobic or anaerobic, were studied. The results showed that methyl group can be transferred from CH(3)B(12) to tin in aquatic solutions as a radical or carbonium, as well as a carbanion. Two explanations for the pH-dependency of the methylation reaction between tin(II) and CH(3)B(12) were proposed: pH-dependency of the equilibrium states of CH(3)B(12), and pH-dependency of inorganic tin(II) species whose reactivity vary with the redox potential in the solution. Salinity can influence the activity of the methyl donor, which cause changes in the methylation efficiency. Kinetic experiments showed that the methylation reaction was pseudo-first-order for CH(3)B(12).

Characterization of Re-188–Sn microparticles used for synovitis treatment

Rhenium-188 labeled tin (Sn) microparticles were developed for pain palliation therapy in the patients suffering from synovitis with acute pain. The rhenium tin microparticles were prepared using stannous chloride and freshly eluted (188)ReO(4)(-) from (188)W/(188)Re generator. The aggregated colloidal particles, packed in a spherical form after boiling for 90-120min were analyzed using electron microscope. The size, surface morphology and stability of microparticles were analyzed by changing temperature and volume conditions. The small colloidal particles clustered and formed spherical microparticles. The 90% of microparticles were in 5-10microm range, after 90min and 120min of boiling. The radiolabeling efficiency was improved to 98% after centrifugation for 10min at 3500rpm. The formulations were stable but the increase in volume had inverse effect on labeling efficiency. No leak was observed from knee area up to 24h with 15-20mCi injection of (188)Re-Sn microparticles. The relief in treated patients, from the pain and inflammation, was observed clinically and by (99m)Tc-MDP perfusion scan.

Photocatalytic performance of Sn-doped TiO2 nanostructured mono and double layer thin films for Malachite Green dye degradation under UV and vis-lights

Nanostructure Sn(4+)-doped TiO(2) based mono and double layer thin films, contain 50% solid ratio of TiO(2) in coating have been prepared on glass surfaces by spin-coating technique. Their photocatalytic performances were tested for degradation of Malachite Green dye in solution under UV and vis irradiation. Sn(4+)-doped nano-TiO(2) particle a doping ratio of about 5[Sn(4+)/Ti(OBu(n))(4); mol/mol%] has been synthesized by hydrotermal process at 225 degrees C. The structure, surface and optical properties of the thin films and/or the particles have been investigated by XRD, BET and UV/vis/NIR techniques. The results showed that the double layer coated glass surfaces have a very high photocatalytic performance than the other one under UV and vis lights. The results also proved that the hydrothermally synthesized nano-TiO(2) particles are fully anatase crystalline form and are easily dispersed in water. The results also reveal that the coated surfaces have hydrophilic property.

Radicals masquerading as electrophiles: dual orbital effects in nitrogen-philic acyl radical cyclization and related addition reactions

Free-radical chemistry has come a long way in a relatively short period of time. The synthetic practitioner takes for granted the wealth of mechanistic and rate constant data now available and can apply free-radical techniques to the synthesis of many different classes of target molecule with confidence. Despite this, there are still mechanistic anomalies that need to be addressed. This Account highlights recent work involving nucleophilic radicals with low-lying unoccupied orbitals, such as acyl, oxyacyl, silyl, stannyl, and germyl radicals. Through interesting singly occupied molecular orbital (SOMO)-pi* and highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) interactions during these reactions, the radicals involved are able to mask as electrophiles, providing high levels of regiocontrol and efficient methods for the synthesis of important heterocycles.