Comparison of three different enrichment strategies for serum low molecular weight protein identification using shotgun proteomics approach

Serum low-molecular weight (LMW) proteins potentially contain useful biological information and their identification can be used to discover novel potential biomarkers. Given the high complexity of serum samples, in the last years several different prefractionation and enrichment strategies have been developed. In this study three different methods, i.e. hydrogel nanoparticles, Proteominer^® peptide ligand affinity beads and Sartorius Vivaspin^® centrifugal ultrafiltration device, were compared and evaluated in order to select the best strategy for the enrichment and prefractionation of LMW proteins. A shotgun proteomics approach was adopted, with in-solution proteolytic digestion of the whole protein mixture and determination of the resulting peptides by nanoHPLC coupled with a high-resolution Orbitrap LTQ-XL mass spectrometer. Data analysis, focusing on the LMW proteome (MW ≤ 40 kDa), has shown that the hydrogel nanoparticles performed better in enriching the LMW protein profiles, with 115 proteins identified against 93 and 95 for Proteominer^® beads and Sartorius Vivaspin^® device, respectively.     

The (100), (111) and (110) surfaces of diamond: an ab initio B3LYP study

We present an accurate ab initio study of the structure and surface energy of the low-index (100), (111) and (110) diamond faces, by using the hybrid Hartree–Fock/density functional B3LYP Hamiltonian and a localised all-electron Gaussian-type basis set. A two-dimensional periodic slab model has been adopted, for which convergence on both structural and energetic parameters has been thoroughly investigated. For all the three surfaces, possible relaxations and reconstructions have been considered; a detailed geometrical characterisation is provided for the most stable structure of each orientation. Surface energy is discussed for all the investigated faces.     

Highly Fluorinated Tris(indazolyl)borate Silylamido Complexes of the Heavier Alkaline Earth Metals: Synthesis,Characterization, and Efficient Catalytic Intramolecular Hydroamination

Heteroleptic silylamido complexes of the heavier alkaline earth elements calcium and strontium containing the highly fluorinated 3‐phenyl hydrotris(indazolyl)borate {F₁₂‐Tp^{4Bo, 3Ph}}^? ligand have been synthesized by using salt metathesis reactions. The homoleptic precursors [Ae{N(SiMe₃)₂}₂] (Ae=Ca, Sr) were treated with [Tl(F₁₂‐Tp^{4Bo, 3Ph})] in pentane to form the corresponding heteroleptic complexes [(F₁₂‐Tp^{4Bo, 3Ph})Ae{N(SiMe₃)₂}] (Ae=Ca ( 1 ); Sr ( 3 )). Compounds 1 and 3 are inert towards intermolecular redistribution. The molecular structures of 1 and 3 have been determined by using X‐ray diffraction. Compound 3 exhibits a Sr ??? MeSi agostic distortion. The synthesis of the homoleptic THF‐free compound [Ca{N(SiMe₂H)₂}₂] ( 4 ) by transamination reaction between [Ca{N(SiMe₃)₂}₂] and HN(SiMe₂H)₂ is also reported. This precursor constitutes a convenient starting material for the subsequent preparation of the THF‐free complex [(F₁₂‐Tp^{4Bo, 3Ph})Ca{N(SiMe₂H)₂}] ( 5 ). Compound 5 is stabilized in the solid state by a Ca???β‐Si?H agostic interaction. Complexes 1 and 3 have been used as precatalysts for the intramolecular hydroamination of 2,2‐dimethylpent‐4‐en‐1‐amine. Compound 1 is highly active, converting completely 200 equivalents of aminoalkene in 16 min with 0.50 mol % catalyst loading at 25 °C.     

Directional distances and their robust versions: Computational and testing issues

Directional distance functions provide very flexible tools for investigating the performance of Decision Making Units (DMUs). Their flexibility relies on their ability to handle undesirable outputs and to account for non-discretionary inputs and/or outputs by fixing zero values in some elements of the directional vector.  and  indicate how the statistical properties of Farrell–Debreu type of radial efficiency measures can be transferred to directional distances. Moreover, robust versions of these distances are also available, for conditional and unconditional measures. B?din, Daraio, and Simar (2012) have shown how conditional radial distances are useful to investigate the effect of environmental factors on the production process. In this paper we develop the operational aspects for computing conditional and unconditional directional distances and their robust versions, in particular when some of the elements of the directional vector are fixed at zero. After that, we show how the approach of B?din et al. (2012) can be adapted in a directional distance framework, including bandwidth selection and two-stage regression of conditional efficiency scores. Finally, we suggest a procedure, based on bootstrap techniques, for testing the significance of environmental factors on directional efficiency scores. The procedure is illustrated through simulated and real data.     

Acid/Vanadium‐Containing Saponite for the Conversion of Propene into Coke: Potential Flame‐Retardant Filler for Nanocomposite Materials

Vanadium‐containing saponite samples were synthesized in a one‐pot synthetic procedure with the aim of preparing samples for potential application as fillers for polymeric composites. These vanadium‐modified materials were prepared from an acid support by adopting a synthetic strategy that allowed us to introduce isolated structural V species (H/V‐SAP). The physicochemical properties of these materials were investigated by XRD analysis and by DR‐UV/Vis and FTIR spectroscopy of CO that was adsorbed at 100 K; these data were compared to those of a V‐modified saponite material that did not contain any Brønsted acid sites (Na/V‐SAP). The surface‐acid properties of both samples (together with the fully acidic H‐SAP material and the Na‐SAP solid) were studied in the catalytic isomerization of α‐pinene oxide. The V‐containing solids were tested in the oxidative dehydrogenation reaction of propene to evaluate their potential use as flame‐retardant fillers for polymer composites. The effect of tuning the presence of Lewis/Brønsted acid sites was carefully studied. The V‐containing saponite sample that contained a marked presence of Brønsted acid sites showed the most interesting performance in the oxidative dehydrogenation (ODH) reactions because they produced coke, even at 773 K. The catalytic data presented herein indicate that the H/V‐SAP material is potentially active as a flame‐retardant filler.     

Layer-by-layer deposition of a polythiophene/Au nanoparticles multilayer with effective electrochemical properties

Multilayers consisting of a water soluble polythiophene derivative and Au nanoparticles have been deposited onto different electrode substrates by means of layer-by-layer deposition technique. The assembly of the films has been performed by taking advantage of the electrostatic interactions between the positively charged imidazolic moiety of the polythiophene chain and the negative charges of citrate ions surrounding Au nanoparticles, as well of the affinity of S to Au. The nanoparticles result stably grafted to the organic matrix. The resulting modified electrodes have been characterised through electrochemical, spectroelectrochemical and microscopic techniques. The results evidenced that a high number of individual nanoparticles is present inside the multilayer. The presence of nanoparticles is of chief importance for most effective charge percolation through the multilayer, as suggested by the responses to electroactive probe species in solution. The electrocatalytic performances of the modified electrodes have been tested with respect to the oxidation of ascorbic acid.