Substrate Specificity of Peptide Adsorption: A Model Study

Applying the contact density chain-growth algorithm to lattice heteropolymers, we identify the conformational transitions of a nongrafted hydrophobic-polar heteropolymer with 103 residues in the vicinity of a polar, a hydrophobic, and a uniformly attractive substrate. Introducing only two system parameters, the numbers of surface contacts and intrinsic hydrophobic contacts, respectively, we obtain surprisingly complex temperature and solvent dependent, substrate-specific pseudo-phase diagrams.Comment: 5 pages, 2 figure

Economic and environmental analysis of the introduction of legumes in livestock farming systems

Legumes in low input systems are becoming increasingly important. The socioeconomic implication of the adoption of novel legumes species has been assessed in sheep and dairy cattle grazing systems in Europe using a biological model which has been linked to linear programming models. In the economic sub-model, the mathematical programming models produce an economic evaluation of the legumes in a farming system context, emphasising the land allocation and the availability of nutrients during the different seasons of the production cycle. Then the paper evaluates the impact of adopting the legumes on the regional income and production. In the UK and Germany, the introduction of legumes results in sizeable gains for the farmers whereas in Italy and France the gains are smaller

A Model of Neutrino Mass and Dark Matter with an Accidental Symmetry

We present a model of radiative neutrino mass that automatically contains an accidental $Z_2$ symmetry and thus provides a stable dark matter candidate. This allows a common framework for the origin of neutrino mass and dark matter without invoking any symmetries beyond those of the Standard Model. The model can be probed by direct-detection experiments and $\mu\rightarrow e+\gamma$ searches, and predicts a charged scalar that can appear at the TeV scale, within reach of collider experiments.Comment: 9 pages, 3 figures; v2 minor correction to PLB version (results unchanged

Factors influencing consumer use of social supermarkets in the UK: A redistribution model providing low-cost surplus food

Food poverty and food waste are prominent societal challenges in the UK. To mitigate their effects, social supermarkets (SSMs) provide high quality surplus food, usually not considered sellable in the mainstream market, to low-income consumers for substantially discounted prices. SSMs aim to supply high quality surplus food in a more dignified shopping experience and thus help lift people from food poverty while allowing customers to exercise personal choice in a supermarket setting; in many cases, they also provide ongoing support and access to additional resources. The aim of this study is to test and estimate relationships between factors that influence consumer intention to use a SSM. A conceptual model was built based on the theory of planned behaviour (TPB) and tested using cross section survey data (N = 486) and structural equation modelling (SEM). The model explained 64% of the variance in intention to use a SSM, with attitudes towards them as the strongest influence. Other influences were price consciousness; knowledge of SSMs, foodbanks or other forms of food assistance programmes (FAP); past experience of food insecurity; perceived risks associated with SSM use; perceptions of consumer normalcy, and perceptions of food quality and safety. This study is, to the best of our knowledge, the first to analyse consumers’ perceptions of SSMs. The findings are relevant for food waste reduction policies as they indicate factors potentially influencing the use of an emerging avenue for food surplus

Filter cassette for high volume air sampler

Filter cassette eliminates or substantially reduces contamination of filter media by extraneous material and facilitates handling

Magnetic Control of Transmission and Helicity of Nano-Structured Optical Beams in Magnetoplasmonic Vortex Lenses

We theoretically investigate the generation of far-field propagating optical beams with a desired orbital angular momentum by using an archetypical magnetoplasmonic tip surrounded by a gold spiral slit. The use of a magnetic material can lead to important implications once magneto-optical activity is activated through the application of an external magnetic field. The physical model and the numerical study presented here introduce the concept of magnetically tunable plasmonic vortex lens, namely a magnetoplasmonic vortex lens, which ensures a tunable selectivity in the polarization state of the generated nanostructured beam. The presented system provides a promising platform for a localized excitation of plasmonic vortices followed by their beaming in the far-field with an active modulation of both light's transmittance and helicity

An In-Depth Computational Study of Alkene Cyclopropanation Catalyzed by Fe(porphyrin)(OCH3) Complexes. The Environmental Effects on the Energy Barriers

Iron porphyrin methoxy complexes, of the general formula [Fe(porphyrin)(OCH3)], are able to catalyze the reaction of diazo compounds with alkenes to give cyclopropane products with very high efficiency and selectivity. The overall mechanism of these reactions was thoroughly investigated with the aid of a computational approach based on density functional theory calculations. The energy profile for the processes catalyzed by the oxidized [FeIII(Por)(OCH3)] (Por = porphine) as well as the reduced [FeII(Por)(OCH3)]- forms of the iron porphyrin was determined. The main reaction step is the same in both of the cases, that is, the one leading to the terminal-carbene intermediate [Fe(Por)(OCH3)(CHCO2Et)] with simultaneous dinitrogen loss; however, the reduced species performs much better than the oxidized one. Contrarily to the iron(III) profile in which the carbene intermediate is directly obtained from the starting reactant complex, the favored iron(II) process is more intricate. The initially formed reactant adduct between [FeII(Por)(OCH3)]- and ethyl diazoacetate (EDA) is converted into a closer reactant adduct, which is in turn converted into the terminal iron porphyrin carbene [Fe(Por)(OCH3)(CHCO2Et)]-. The two corresponding transition states are almost isoenergetic, thus raising the question of whether the rate-determining step corresponds to dinitrogen loss or to the previous structural and electronic rearrangement. The ethylene addition to the terminal carbene is a downhill process, which, on the open-shell singlet surface, presents a defined but probably short-living diradicaloid intermediate, though other spin-state surfaces do not show this intermediate allowing a direct access to the cyclopropane product. For the crucial stationary points, the more complex catalyst [Fe(2)(OCH3)], in which a sterically hindered chiral bulk is mounted onto the porphyrin, was investigated. The corresponding computational data disclose the very significant effect of the porphyrin skeleton on the reaction energy profile. Though the geometrical features around the reactive core of the system remain unchanged, the energy barriers become much lower, thus revealing the profound effects that can be exerted by the three-dimensional organic scaffold surrounding the reaction site.