Eigenvalues for radially symmetric fully nonlinear singular or degenerate operators

In this paper we present a one dimensional and radial theory for the existence of eigenvalues and eigenfunctions for fully nonlinear elliptic (α+1)$(\alpha +1)$-homogeneous operators, α>−1$\alpha >-1$. A general theory for the first eigenvalue and eigenfunction exists in the frame of viscosity solutions, but in this particular case a simpler theory can be established, that extends, via degree theory, to obtain the complete set of eigenvalues and eigenfunctions characterized by the number of zeros.     

A collaborative environment for developing and validating predictive tools for protein biophysical characteristics

The exchange of information between experimentalists and theoreticians is crucial to improving the predictive ability of theoretical methods and hence our understanding of the related biology. However many barriers exist which prevent the flow of information between the two disciplines. Enabling effective collaboration requires that experimentalists can easily apply computational tools to their data, share their data with theoreticians, and that both the experimental data and computational results are accessible to the wider community. We present a prototype collaborative environment for developing and validating predictive tools for protein biophysical characteristics. The environment is built on two central components; a new python-based integration module which allows theoreticians to provide and manage remote access to their programs; and PEATDB, a program for storing and sharing experimental data from protein biophysical characterisation studies. We demonstrate our approach by integrating PEATSA, a web-based service for predicting changes in protein biophysical characteristics, into PEATDB. Furthermore, we illustrate how the resulting environment aids method development using the Potapov dataset of experimentally measured ΔΔG_fold values, previously employed to validate and train protein stability prediction algorithms.     

Precipitation of silver/palladium alloy platelets from homogeneous solutions

Dispersed silver/palladium (Ag/Pd) nanoplatelets were prepared by delivering in parallel solutions of mixed metal nitrates and L-ascorbic acid into a nitric acid solution containing Arabic gum. The shape and size of bimetallic nanoparticles varied with the silver/palladium weight ratio and the concentration of nitric acid. The optimum conditions for platelets formation were a palladium content of ~2.0 wt.% and nitric acid concentrations above 1.0 mol dm(-3). The data presented show that both parameters play a critical role in the nucleation and growth of AgPd particles. A mechanism explaining the formation of the bimetallic nanoplatelets is proposed.     

Synthesis, 5-hydroxytryptamine1A receptor affinity and docking studies of 3-[3-(4-aryl-1-piperazinyl)-propyl]-1H-indole derivatives

A series of 3-[3-(4-aryl-1-piperazinyl)-propyl]-1H-indole derivatives (12a-h) was synthesized and evaluated for binding affinity at the human 5-hydroxytryptamine(1A) receptor (5-HT(1A)R) compounds (12b) and (12h) showed the highest 5-HT(1A) receptor affinity (IC(50)=15 nM). Molecular docking studies with all the compounds in a homology model of 5-HT(1A) showed that the main interaction anchoring the ligand in the receptor was a charge-reinforced bond between the protonated nitrogen atom (N-4) of the piperazine ring and Aspartate(3.32).     

Synthesis and Properties of Oligo-/Polymers Based on a “Flexible” Swivel-Cruciform Structure

We have introduced the concept of the so-called swivel type cruciforms as a highly flexible tool to tune the molecular properties from amorphous to highly crystalline features. Simple alkoxy substituted binaphthyl building blocks have been introduced randomly into poly(9,9-dioctylfluorene) (PFO) thereby suppressing the formation of side-chain crystallization. On the other hand the all aryl penta-thiophene based cruciform exhibited strong π–π interaction between the arms and gave one of the highest values reported to date for wet processed organic field effect transistors (OFETs) utilising oligothiophenes.     

Hydrogen‐bonded bilayers in ­piperazinium(2+) bis(mandelate) bis(methanol) solvate

In the title compound, C₄H₁₂N₂²⁺·2C₈H₇O₃^?·2CH₄O, the cations lie across centres of inversion and are disordered over two orientations with equal occupancy; there are equal numbers of (R)‐ and (S)‐mandelate anions present (mandelate is α‐hydroxy­benzene­acetate). The anions and the neutral water mol­ecules are linked by O—H?O hydrogen bonds [O?O 2.658 (3) and 2.682 (3) Å, and O—H?O 176 and 166°] into deeply folded zigzag chains. Each orientation of the cation forms two symmetry‐related two‐centre N—H?O hydrogen bonds [N?O 2.588 (4) and 2.678 (4) Å, and N—H?O 177 and 171°] and two asymmetric, but planar, three‐centre N—H?(O)₂ hydrogen bonds [N?O 2.686 (4)–3.137 (4) Å and N—H?O 137–147°], and by means of these the cations link the anion/water chains into bilayers.     

Nickel Nanopillar Arrays Electrodeposited on Silicon Substrates Using Porous Alumina Templates

Nickel nanopillar arrays were electrodeposited onto silicon substrates using porous alumina membranes as a template. The characterization of the samples was done by scanning electron microscopy, X-ray diffraction, and alternating force gradient magnetometry. Ni nanostructures were directly grown on Si by galvanostatic and potentiostatic electrodeposition techniques in three remarkable charge transfer configurations. Differences in the growth mechanisms of the nanopillars were observed, depending on the deposition method. A high correlation between the height of the nanopillars and the charge synthesis was observed irrespective of the electrochemical technique. The magnetization measurements demonstrated a main dependence with the height of the nanopillars. The synthesis of Ni nanosystems with a controllable aspect ratio provides an effective way to produce well-ordered networks for wide scientific applications.     

Relationship between basicity and nucleophilicity

The empirical concepts of basicity and nucleophilicity are related but not strictly proportional. Hence, the aim of this study is to help in elucidating the range where both concepts are directly proportional. To do this, the relationship between a recently introduced nucleophilicity index and the proton affinity (PA) of several families of bases has been studied. A good correlation between the PA and the nucleophilicity index using HF and HCN as electrophilic partner has been found. Our studies show that the correlation exists only when the interaction is soft–soft in character and for strong bases with weak acids. However, the relationship is not only valid for exothermic reactions as it has been previously postulated but also for endothermic reactions. Copyright © 2007 John Wiley & Sons, Ltd.     

A Mössbauer effect study of structural ordering in rapidly quenched Fe–Ga alloys

Samples of Fe_100−xGa_x (x=8.3, 17.9, 20.5 and 23.3) were prepared by rapid solidification from the melt using a single Cu roller. X-ray diffraction studies of all samples showed them to be single phase with the disordered BCC structure. No evidence of superlattice reflections from D0₃ ordering was observed for any of the samples. Room-temperature ⁵⁷Fe Mössbauer effect spectra indicated that all samples were ferromagnetically ordered. Spectra were fit to distributions of hyperfine fields. The x=8.3 sample showed a hyperfine field distribution that was single peaked and indicated a reasonably random distribution of local Fe environments. The x=17.9 and 20.5 samples showed hyperfine field distributions that were bimodal and indicated two distinct local Fe environments. The x=23.3 sample showed three distinct field components. It is suggested that the x=8.3, 17.9 and 20.5 alloys are primarily a disordered BCC phase. The x=8.3 alloy shows a small amount of short-range Ga–Ga pairing, while this short-range pairing is significantly greater in the x=17.9 and 20.5 alloys. The three field components in the x=23.3 alloy correspond well to the two sites associated with the D0₃ phase and a third component corresponding to a remaining L1₂ phase suggesting the presence of at least short-range D0₃ clustering in this alloy.