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This report shows that the size, shape, and composition of presynthesized copper nanoparticles can be nanoengineered through exploiting concurrent interparticle aggregative growth and interfacial carbon−sulfur cleavage in a thermally activated evolution route. This is demonstrated by thermally activated processing of ultrafine copper nanoclusters encapsulated with thiolate monolayer (Cu n (SR) m ) toward semiconducting copper sulfide (Cu2S) nanodiscs with controllable sizes and shapes. Under controlled temperatures (120−150 °C), the ultrafine Cu n (SR) m nanoclusters, with a size of ∼0.5 nm evidenced by TEM, SAXS-WAXS, DCP-AES, and MALDI-TOF measurements, were shown to evolve into thiolate-capped Cu2S nanodiscs via thermally activated coalescence and copper-catalyzed interfacial C−S cleavage reactivities. The Cu2S nanodiscs, as confirmed by XPS and HRTEM analyses, exhibited controllable and monodispersed sizes depending on the thermal processing parameters, ranging from 5 to 35 nm in the disk dimension and 3−6 nm in the thickness dimension. These nanodiscs are stable and display remarkable 1D/2D ordering upon self-assembly. This process is not a simple digestive ripening of smaller particles because it involves an aggregative nucleation and growth process distinctively different from traditional ripening and a reactive carbon−sulfur bond cleavage controlled by the catalytic effect of copper under the specified temperatures. The coupling of the thermally activated coalescence and C−S bond cleavage to convert the ultrafine Cu nanoclusters toward the formation of Cu2S nanodiscs is highly effective for tuning nanoscale size, shape, and composition, and could find applications in nanoengineering a variety of semiconducting nanocrystals for applications in nanostructured electronic, sensing, and photochemical devices.

A symmetrical alpha,omega-substituted sexithiophene derivative containing thermally removable branched ester solubilizing groups has been prepared. These oligomers can be solution cast into thin films and then thermolyzed to remove the solubilizing group, leaving short pendant alkene groups on the oligomer. Device testing of thin film transistors shows an increase in hole mobility from 1 x 10-5 cm2/(V s) with on/off ratios of approximately 100 before thermolysis to 5 x 10-2 cm2/(V s) with on/off ratios >105 after thermolysis. This method offers an attractive route to easily processed and highly performing thiophene oligomers.

A vacuolating cytotoxin encoded by vacA in Helicobacter pylori is known as a potential virulent determinant. The relationship between different vacA alleles, vacuolating ability, and H. pylori-related diseases was investigated. Genetic analysis of 119 isolates from Taiwanese patients revealed that 104 strains were s1a/m2, 13 strains were characterized as the s1a/m1T type, which was more homologous to the s1a/m1 strains, and 2 were characterized as the s1a/m1Tm2 chimeric type. Production of high-grade cytotoxin among 11 strains with s1a/m1T was higher (72.7%) than among 66 strains with s1a/m2 (21.2%) (P < .01). Peptic ulcer occurred in 76.9% of 13 patients with s1a/m1T strains compared with 46.2% of 104 patients with s1a/m2 strains (P < .05). These results suggest that s1a/m1T strains are associated with increased cytotoxic activity and higher ulcer prevalence than are s1a/m2 strains.