Strain Influences the Hydrogen Evolution Activity and Absorption Capacity of Palladium

Strain engineering can increase the activity and selectivity of an electrocatalyst. Tensile strain is known to improve the electrocatalytic activity of palladium electrodes for reduction of carbon dioxide or dioxygen, but determining how strain affects the hydrogen evolution reaction (HER) is complicated by the fact that palladium absorbs hydrogen concurrently with HER. We report here a custom electrochemical cell, which applies tensile strain to a flexible working electrode, that enabled us to resolve how tensile strain affects hydrogen absorption and HER activity for a thin film palladium electrocatalyst. When the electrodes were subjected to mechanically‐applied tensile strain, the amount of hydrogen that absorbed into the palladium decreased, and HER electrocatalytic activity increased. This study showcases how strain can be used to modulate the hydrogen absorption capacity and HER activity of palladium.     

Fractional iteration and a generalised abel's equation in two variables

Aequationes mathematicae -     

Curvature-dependent surface tension of a growing droplet

A ghost interface simulation technique is developed and applied to supersaturated Lennard-Jones liquid-vapor interfaces. It is shown that the surface tension decreases approximately linearly with the supersaturation ratio and that it vanishes at the spinodal. The effect leads to a curvature-dependent surface tension since, it is argued, the local supersaturation of the vapor above a droplet is greater than in the bulk due to slow diffusion in the vapor phase. An analytic approximation is given for the local supersaturation ratio, and an analytic expression for this contribution to Tolman's length is derived. The theory gives a smaller critical radius and reduces the free energy barrier to nucleation compared to classical homogeneous nucleation theory, which have important implications for the kinetics of droplet and bubble formation.     

Practical synthesis and elaboration of methyl 7-chloroindole-4-carboxylate

A synthesis of a previously unknown indole derivative is presented. The route reported herein allows for the preparation of multihundred gram quantities of material without any chromatographic purification. Conditions are presented for the Pd-catalyzed elaboration of one of the "diversity generating elements" of this important pharmacophore.     

Optical behavior of antibiofouling additives in environment‐friendly coverglass materials for bio‐sensors and solar panels

Solar panels and bio‐optical sensors play a significant and growing role in a number of applications that are of importance to many organizations. Many of these instruments require a high transmission of radiation into the device for it to work properly. A major issue faced is that harsh marine environments often aid in the growth or development of fouling on the coverglass used to protect the instruments. Over a period of time in an ocean environment, some plant or animal may attach itself to the coverglass, ultimately obscuring the glass and rendering the instrument useless. As such, an antifouling mechanism is needed for these instruments that is inexpensive, long‐lasting, and environment friendly. The approach discussed herein involves the use of known antifouling chemicals which have been incorporated into the polymer matrix. Polymethylmethacrylate (PMMA), bisphenol A polycarbonate (Bis A PC), and a co‐polyterephthalate (CPTE) were examined. The plaques are optically transparent and previous work has shown that, for most samples, the materials display a minimal decrease in mechanical behavior upon the addition of the algaecides. This paper will discuss the effects on the materials' optical properties when exposed to both harsh marine conditions as well as high intensity UV light. Specifically, the decrease in transmission of visible light was examined over a 6 month period of time. Copyright © 2008 John Wiley & Sons, Ltd.     

Gold(I) and Silver(I) Complexes with Thioether Functionalized Silylamido Ligands

The thioether functionalized aminosilanes Me₂Si(NH‐C₆H₄‐2‐SR)₂ (R = Ph, Me) were lithiated with nBuLi and subsequently reacted with AgCl in the presence of PMe₃ or with [AuCl(PMe₃)]. In the case of Me₂Si(NH‐C₆H₄‐2‐SPh)₂ the dinuclear complexes [M₂{Me₂Si(NC₆H₄‐2‐SPh)₂}(PMe₃)₂] (M = Ag; Au) were isolated. The analogous reactions starting from Me₂Si(NH‐C₆H₄‐SMe)₂ afforded the dinuclear gold complex [Au₂{Me₂Si(NC₆H₄‐2‐SMe)₂}(PMe₃)₂] and the tetranuclear silver complex [Ag₄{Me₂Si(NC₆H₄‐2‐SMe)₂}₂(PMe₃)₂]. In the dinuclear compounds of the type [M₂{Me₂Si(NC₆H₄‐2‐SR)₂}(PMe₃)₂], each of the silylamide N atoms is connected to a M(PMe₃) group to give a nearly linear N–M–P arrangement with Ag–N and Au–N bonds in the range of 212.0(4)–213.3(4) pm and 205.3(3)–208.1(9) pm, respectively. [Ag₄{Me₂Si(NC₆H₄‐2‐SMe)₂}₂(PMe₃)₂] consists of a central Si₂N₄Ag₂ ring with linearly coordinated Ag atoms (Ag‐N: 223.1(4)–222.1(4) pm) and two peripheral Ag(PMe₃) units, which are connected to the amido N atoms in a chelating mode. The relatively short transannular Ag ··· Ag separation (277.6(1) pm) within the Si₂N₄Ag₂ ring hints for argentophilic interactions. The peripheral Ag atoms are three coordinated with Ag–N distances of 233.9(4)–242.8(4) pm.     

UnyLinker dimer impurity characterization and process improvement

Herein, we describe the isolation and characterization of a UnyLinker dimer which, if left uncontrolled, can become incorporated in oligonucleotide products. The dimer is formed as a result of an unusual intermolecular osmium-catalyzed etherification. We demonstrate that by simply replacing H₂O₂ as the co-oxidant with NMO, none of the UnyLinker dimer impurity is formed.