The DINGO dataset: a comprehensive set of data for the SAMPL challenge

Part of the latest SAMPL challenge was to predict how a small fragment library of 500 commercially available compounds would bind to a protein target. In order to assess the modellers' work, a reasonably comprehensive set of data was collected using a number of techniques. These included surface plasmon resonance, isothermal titration calorimetry, protein crystallization and protein crystallography. Using these techniques we could determine the kinetics of fragment binding, the energy of binding, how this affects the ability of the target to crystallize, and when the fragment did bind, the pose or orientation of binding. Both the final data set and all of the raw images have been made available to the community for scrutiny and further work. This overview sets out to give the parameters of the experiments done and what might be done differently for future studies.     

SERS activity of pulsed laser ablated silver thin films with controlled nanostructure

The surface‐enhanced Raman scattering (SERS) activity of silver thin films deposited by the pulsed laser ablation technique was investigated. The samples were grown in a controlled Ar atmosphere at pressures ranging between 10 and 70 Pa, and changing the number of laser pulses. Different surface morphologies, from isolated nearly spherical nanoparticles (NPs) to larger islands with smooth edges, were observed by means of scanning and transmission electron microscopies, as a function of the different deposition conditions adopted. SERS measurements were performed by soaking the samples in rhodamine 6G aqueous solutions over the concentration range between 1.0 × 10⁻⁴ and 5.0 × 10⁻⁸ M . Raman spectra were acquired using both the 632.8 and 514.5 nm excitation sources. The dependence of the SERS activity of the samples on the observed surface morphology is presented and discussed. The presence of the so called hot spots is envisaged. Copyright © 2011 John Wiley & Sons, Ltd.     

The interaction between radiation and the Linen of Turin

In this paper, we study the possible interactions between radiation and the Linen of Turin. The work is in line with the research focused, by scholars and scientists, on the detection mechanism of the Shroud body image formation. We have analysed the interactions between thermal, UV and particle radiation with the linen fabric. The performed analysis shows that any hypothesis of the Shroud body image formation by radiation must be rejected. Only the background was produced by the action of electromagnetic radiation.     

Microchemical investigations of historical coins

Microchemical investigations were carried out on ancient silver coins originated from the same country but of different historical periods between the fifth and the second centuries B.C. Energy-Dispersive X-ray microanalysis in a Scanning Electron Microscope (SEM-EDX) was employed to obtain qualitative and semi-quantitative information about the chemical composition of these coins. SEM-EDX analyses employ an electron beam of 20?keV, which interacts with the sample leading to the emission of characteristic X-rays, to determine elements present in the surface patina, closely related to the sample preservation. In the X-ray photoelectron spectroscopy (XPS) analysis a monochromatic Al Kα radiation (1486.6?eV) interacts with the sample and photoelectrons are detected as secondary radiation, to investigate about coins elemental composition. Moreover a beam of Ar⁺ ions with an energy of 3?keV was used for the sputtering procedure in order to perform depth profile measurements, from the surface (patina composition) down to deeper layers. Useful information about production, chronological period and utilization places of coins are obtained to support a correct dating of these samples.     

Gas pressure effects on the structure of CNx thin films deposited by laser ablation

Carbon nitride thin films with different nitrogen concentration have been deposited at different N₂ and N₂/Ar mixed partial pressures. Time-integrated optical emission spectroscopy measurements have been performed to gather information on the nature of the chemical species present in the plasma. Both the CN and C₂ molecular species have been observed. Fast photography imaging of the expanding plume revealed the change of the dynamics from a free expansion at low pressure to a shock wave formation followed then by the plume stopping upon increasing the gas pressure values. Raman and XPS spectroscopy measurements performed on the deposited thin films revealed that the films, structure strongly depends on the dynamics of the expansion plasma regime rather than on the partial pressure at which the deposition takes place.     

Dynamics of a pulsed laser generated tin plasma expanding in an oxygen atmosphere

Semiconducting tin oxide can be successfully deposited by means of the laser ablation technique. In particular by ablating metallic tin in a controlled oxygen atmosphere, thin films of SnO _x have been deposited. The partial oxygen pressure at which the films are deposited strongly influences both the stoichiometry and the structural properties of the films. In this work, we present a study of the expansion dynamics of the plasma generated by ablating a tin target by means of a pulsed laser using time and space resolved optical emission spectroscopy and fast photography imaging of the expanding plasma. Both Sn I and Sn II optical emission lines have been observed from the time-integrated spectroscopy. Time resolved-measurements revealed the dynamics of the expanding plasma in the ambient oxygen atmosphere. Stoichiometry of the films has been determined by means of X-ray photoelectron spectroscopy and correlated to the expansion dynamics of the plasma.     

Comparative Study of Mixed Monolayers of a Calixarene with a Fatty Acid and a Non-Amphiphilic Nematic Liquid Crystal

Abstract

Many nematic liquid crystals (NLCs) lack a polar headgroup and thus are not able to form stable monolayers at the air/water (a/w) interface. A way to obtain monomolecular films of these compounds is to incorporate them into host monolayers of amphiphilic molecules. We report a comparative investigation of mixed films of Calix[4]resorcinarene O-octacarboxymethylated (CRO) with the non-amphiphilic NLC MBBA and with the amphiphilic stearic acid (SA). The comparative study is useful for a better understanding of the characteristics of the CRO-MBBA mixed films. Surface-pressure and surface-potential measurements on the monolayers at a/w interface, as well as ellipsometric and spectroscopic measurements on transferred Langmuir-Blodgett (LB) films, confirm that MBBA is additively incorporated into CRO films.     

Comparison of fatty acid profile and antioxidant potential of extracts of seven Citrus rootstock seeds

The extracts of seven Citrus rootstock seeds have been compared regarding fatty acid profile and antioxidant potential. Sour orange (Citrus aurantium L.) was found to contain the highest oil amount (34%), while the Poncirus trifoliata cultivars contained the highest percentage of unsaturated fatty acids (84-87%). In addition, the antioxidant properties of the extracts from defatted seeds have been evaluated by measuring their radical scavenging activity against 2,2'-diphenyl-1-picrylhydrazyl. The highest antioxidant activities were observed in the case of the acetone extract of sour orange and Citrumelo Swingle (76% and 75%, respectively), at a concentration of 0.17?mg?mL(-1). Moreover, the total phenolic content of the extracts, determined using the Folin-Ciocalteau reagent, was found to be correlated with the radical scavenging activity results. The acetone extracts of sour orange and Citrumelo Swingle exhibited the highest phenolic content [112.3 and 103.4?mg gallic acid equivalent?g(-1) dry sample weight, respectively].     

High‐Density DNA Functionalization by a Combination of Cu‐Catalyzed and Cu‐Free Click Chemistry

We report the regioselective Cu‐free click modification of styrene functionalized DNA with nitrile oxides. A series of modified oligodeoxynucleotides (nine base pairs) was prepared with increasing styrene density. 1,3‐Dipolar cycloaddition with nitrile oxides allows the high density functionalization of the styrene modified DNA directly on the DNA solid support and in solution. This click reaction proceeds smoothly even directly in the DNA synthesizer and gives exclusively 3,5‐disubstituted isoxazolines. Additionally, PCR products (300 and 900 base pairs) were synthesized with a styrene triphosphate and KOD XL polymerase. The click reaction on the highly modified PCR fragments allows functionalization of hundreds of styrene units on these large DNA fragments simultaneously. Even sequential Cu‐free and Cu‐catalyzed click reaction of PCR amplicons containing styrene and alkyne carrying nucleobases was achieved. This new approach towards high‐density functionalization of DNA is simple, modular, and efficient.     

On the influence of the mass ablated by a laser pulse on thin film morphology and optical properties

To know and to control experimental parameters that play a role in laser ablation is vital to define film properties. Among the others, laser fluence is commonly used. Yet, when plasma expansion dynamics takes place through an ambient gas, the relation between the ablated mass per pulse and gas mass is critical and till now it was poorly investigated. While the gas mass is fixed by the pressure in the deposition chamber, the ablated mass is not unequivocally determined by the laser fluence. For a given fluence value the ablated mass changes as a function of the irradiated target area. Here, we show that nanostructured silver thin films deposited keeping unaltered the laser fluence, while changing in a controlled way the irradiated area and hence the ablated mass per pulse, display markedly differentiated morphological and optical properties, as evidenced by electron microscopy and UV–Vis and Raman spectroscopies.