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There are very few studies that have investigated directly the effect of an oxide film on tin whisker growth, since the 'cracked oxide theory' was proposed by Tu in 1994 [K.-N. Tu: Phys. Rev., 1994, 49, (3), 2030-2034]. The current study has investigated the effect of an electrochemically produced oxide on tin whisker growth, for both Sn-Cu electrodeposits on Cu and pure Sn electrodeposits on brass. X-ray photoelectron spectroscopy (XPS) has been used to investigate the effect of the applied electrochemical oxidation potential on the oxide film thickness. Focused ion beam has been used to prepare cross sections from electrodeposited samples to investigate the influence of the electrochemically formed oxide film on deposit microstructure during long-term room temperature storage. The XPS studies show that the thickness of electrochemically formed oxide film is directly influenced by the applied potential and the total charge passed. Whisker growth studies show that the electrochemical oxidation treatment mitigates whisker growth for both Sn-Cu electrodeposits on Cu and pure Sn electrodeposits on brass. For Sn electrodeposits on brass, the electrochemically formed oxide greatly reduces both the formation of zinc oxide at the surface and the formation of intermetallic compounds, which results in the mitigation of tin whisker growth. For Sn-Cu electrodeposits on Cu, the electrochemically formed oxide has no apparent effect on intermetallic compound formation and acts simply as a physical barrier to hinder tin whisker growth. [ABSTRACT FROM AUTHOR]

Tin sulfide films were deposited from an aqueous solution of tin dichloride, thiacetamide, and disodium citrate. X-ray diffraction, atomic force microscopy, ultraviolet–visible spectrophotometry, and electrical measurement were used to characterize the films. The films directly deposited at 70 and 80 °C for 1 and 2 h showed thicknesses of 70–400 and 120–650 nm, respectively. But the deposition at 40 °C for 1 h (nucleation step) made the films subsequently deposited at 60–80 °C denser and thicker (∼1600–7500 nm) than directly deposited films. Average transmittances of the films in UV–visible range decrease with increase in the thickness and are only in range of 0.33–2.3% for the films deposited with the nucleation step. The band gap energies of the films estimated from the transmittance spectra are in the range of ∼1.37–1.55 eV. Moreover, the films are p-type conductive. The electrical resistance and carrier mobility are in the ranges of 0.3–1.4 × 105Ω cm and 0.77–1.56 cm2(V s)−1, respectively. The films deposited with the nucleation step show lower resistance and higher carrier mobility than those deposited without nucleation because of their denser film microstructure and larger film thickness. [ABSTRACT FROM AUTHOR]

Detailed analysis of chlorinated higher fullerenes has revealed basic principles of halogen addition to fullerenes. The resulting halogenation pattern appears to be controlled by the presence of triple hexagon substructures, which tend to generate a new aromatic system during chlorination. [ABSTRACT FROM AUTHOR]

An improved synthetic approach to tenatoprazole 1 is described. It started from 2,3,5-trimethyl-4-nitropyridine-N-oxide 2 with acetic anhydride via rearrangement and hydrolysis to give 3, Chlorination with SOCl2 yielded 2-chloromethyl-3,5-dimethyl-4-nitropyridine hydrochloride 4, then 4 condensed with 2-mercapto-5-methoxy imidazole [4,5-b]pyridine 5 to give 5-methoxy-2-[(4-nitro-3,5-dimethyl-2-pyridinyl)methylthio]imidazole[4,5-b]pyridine 6. At last the title compound 1 was produced by two methods: 6 was oxidized with MCPBA and then methoxylated with CH3ONa to give 1 and 6 was first methoxylated with CH3ONa and then oxidized with MCPBA to give 1. The overall yield is around 26% for both five-step syntheses. [ABSTRACT FROM AUTHOR]

In order to define the properties which influence the non-stick behavior of surfaces we need to understand the qualities of the adherate, namely the barnacle or its adhesive, and the qualities of the joint between the adherate and the substrate surface. This investigation has dealt with interfaces between barnacles and a diverse range of materials which were studied by various microscopic techniques: light microscopy (LM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). A comparison of barnacles grown on non-stick surfaces to those grown on easy-to-attach surfaces revealed differences in the calcified part of the barnacle base as well as in the adhesive's ultrastructure. In contrast to barnacles grown on easy-to-attach substrata, barnacles on non-stick surfaces typically possess a bell-shaped base plate and a thick multilayered adhesive plaque. This peculiar feature is supposed to be a result of downward growth of the parietal plates and subsequent detachment of the weakly adhered base area. SEM investigations revealed that barnacle cement was composed of globules of nanometer size, which formed specific structures depending on the substratum. Globules, united into a thin, dense sheet of adhesive, and closely woven networks were seen on surfaces that had no foul-release properties. These formations suggested a progressive cross-linking process. In contrast, loose networks of hydrated adhesive threads were detected on non-stick surfaces. Comparative AFM investigations on the adhesive in its natural state confirmed the existence of adhesive strands and globular structures. The adhesive characteristics found on a nonstick surface (loosely matted strands, high water content) coincided with low cohesive strength of the adhesive. The formation of highly hydrated adhesive plaques is thought to be a repair mechanism to bridge the gap between the barnacle base and the substratum. At the expense of reduced cross-linking and low cohesive strength the formation of a loose web and water uptake results in higher elasticity. [ABSTRACT FROM AUTHOR]

The 1890s were a watershed in the history of the Cornish tin mining industry. As a consequence of a spectacular fall in the price of tin on the world market, an age-old system of capitalist mining in Cornwall, England was effectively eliminated. It was marked by a greater sensitivity to international prices than at any previous time combined with relatively inflexible production costs to put the Cost Book system of mining under intense strain. Tin prices fell consistently from 1888 to 1897, from £117.3 per ton for black tin, to £65.4 per ton. Moreover, there was a long-term decline in the grade of ore mined in Cornwall, which tended to accentuate the impact of price falls and debarred the management from adopting one of its most convenient strategies in times of falling profits, as that of the mining of higher grade ore bodies. Thus in 1873 all Cornish tin mines produced dressed tin ore containing 58.5 per cent of metallic tin in every ton. In 1896, a smaller number of mines produced tin ore containing 53.3 per cent of metallic tin in each ton, at a time when prices were 56.6 per cent below their 1873 level.