6,332 publications from this institution
Luminescent Os(II) and Ir(III) complexes containing a tripodal-type structure terminalized with three thiol derivatives are described. The tripod is introduced through derivatization, with a rigid spacer, of a phenanthroline ligand coordinated to the metal ion, and the entire structure possesses axial geometry. The geometry of the complexes combined with the three anchoring sites, the thiol groups, allows the complexes to adopt an almost perpendicular arrangement to the surfaces and the formation of a well-packed monolayer on Au substrates. The photophysical and electrochemical behavior of the complexes is studied in solution and on surfaces. Furthermore, a self-assembled monolayer (SAM) of Os(II) complexes on an ultraflat Au surface is used to fabricate a metal–molecule–metal junction with Au and In Ga eutectic as electrodes. The Os(II) SAM in the tunneling junction exhibits rectification behavior which is opposite in direction to that which we have previously shown for Ru(II) SAMs.
The introduction of an ambient-temperature route for integrating high-mobility semiconductors on flexible substrates could enable the development of novel electronic and photonic devices with the potential to impact a broad spectrum of applications. Here we review our recent studies demonstrating that high-quality single-crystal nanowires (NWs) can be assembled onto flexible plastic substrates under ambient conditions to create FETs and light-emitting diodes. We also show that polymer substrates can be patterned through the use of a room temperature nanoimprint lithography technique for the general fabrication of hundred-nanometer scale features, which can be hierarchically patterned to the millimeter scale and integrated with semiconductor NWs to make high-performance FETs. The key to our approach is the separation of the high-temperature synthesis of single-crystal NWs from room temperature solution-based assembly, thus enabling fabrication of single-crystal devices on virtually any substrate. Silicon NW FETs on plastic substrates display mobilities of 200 cm/sup 2/-V/sup -1/-s/sup -1/, rivaling those of single-crystal silicon and exceeding those of state-of-the-art amorphous silicon and organic transistors currently used for flexible electronics. Furthermore, the generality of this bottom-up assembly approach suggests the integration of diverse nanoscale building blocks on a variety of substrates, potentially enabling far-reaching advances in lightweight display, mobile computing, and information storage applications.
The consumption of sugar-sweetened beverages (SSBs), such as sodas, fruit drinks, sports drinks, and energy drinks, has increased considerably over the past decade, in parallel with the rising prevalence of obesity. In this session, presenters discussed the adverse cardiometabolic effects of SSB consumption and the role of healthy drinking in cardiovascular risk reduction.
A general synthetic method has been developed to control both the diameter and the length of nanowires during growth. This approach exploits monodisperse nanocluster catalysts to define both the nanowire diameter and the initiation of nanowire elongation during growth by a vapor−liquid−solid mechanism. To demonstrate this new approach, crystalline indium phosphide (InP) nanowires have been synthesized using a laser catalytic growth (LCG) process combined with gold nanocluster catalysts. InP nanowires with nearly monodisperse diameters of 10, 20, and 30 nm were grown from nanocluster catalysts having diameters of 10, 20, and 30 nm, respectively. High-resolution transmission electron microscopy studies show that the InP nanowires prepared in this manner are single crystals with a [111] growth direction. In addition, studies of nanowire growth as a function of growth time have shown that nanowire length is directly proportional to growth time and have enabled the preparation of InP nanowires with narrow length distributions centered at 2, 4, 6, and 9 μm. The new level of synthetic control afforded by our approach should enable better-defined fundamental studies of nanowires and open up new opportunities for the assembly of functional nanodevices.
Background and Purpose— Few studies have examined the association between folate intake and risk of stroke, although numerous studies have suggested that high levels of homocysteine are positively related to stroke. We aim to assess the relation between folate intake and stroke incidence among women participating in the Nurses’ Health Study. Methods— 83 272 female nurses aged 34 to 59 years in 1980 and residing in 11 US states were followed-up for 18 years. Follow-up questionnaires were sent biennially to update information on diet and to identify newly diagnosed cases of stroke and other illnesses. Results— During 1 379 614 person-years of follow-up from 1980 to 1998, we identified 1140 incident cases of stroke. Using age-adjusted and multivariable-adjusted models, no appreciable association between the intake of folate and total incidence of stroke was observed [relative risk in the multivariable-adjusted model for the highest quintile of folate intake (median=696 μg/d) compared with the lowest quintile (median=158 μg/d) was 1.01 (95% confidence interval [CI]: 0.79 to 1.29), P for trend=0.8]. Similar null results were found in secondary analyses on stroke subtypes (ischemic, thrombotic, embolic, subarachnoid hemorrhage, intraparenchymal hemorrhage) and in analyses that separately assessed dietary folate (excluding supplement users) and folate supplement intake. Conclusions— Folate intake was not associated with incident stroke among women participating in the Nurses’ Health Study.
