Modelling and solving English Peg Solitaire

Peg Solitaire is a well known puzzle, which can prove difficult despite its simple rules. Pegs are arranged on a board such that at least one ‘hole’ remains. By making draughts/checkers-like moves, pegs are gradually removed until no further moves are possible or some goal configuration is achieved. This paper considers the English variant, consisting of a board in a cross shape with 33 holes. Modelling Peg Solitaire via constraint or integer programming techniques presents a considerable challenge and is examined in detail. The merits of the resulting models are discussed and they are compared empirically. The sequential nature of the puzzle naturally conforms to a planning problem, hence we also present an experimental comparison with several leading AI planning systems. Other variants of the puzzle, such as ‘Fool's Solitaire’ and ‘Long-hop’ Solitaire are also considered.     

Self‐Assembled Conjugated Thiophene‐Based Rotaxane Architectures: Structural,Computational, and Spectroscopic Insights into Molecular Aggregation

A comparative study of the self‐assembly at a variety of surfaces of a dithiophene rotaxane 1 ?β‐CD and its corresponding dumbbell, 1, by means of atomic force microscopy (AFM) imaging and scanning tunneling microscopy (STM) imaging on the micrometer and nanometer scale, respectively. The dumbbell is found to have a greater propensity to form ordered supramolecular assemblies, as a result of π–π interactions between dithiophenes belonging to adjacent molecules, which are hindered in the rotaxane. The fine molecular structure determined by STM was compared to that obtained by molecular modelling. The optical properties of both rotaxane and dumbbell in the solid state were investigated by steady‐state and time‐resolved photoluminescence (PL) experiments on spin‐cast films and diluted solutions. The comparison between the optical features of the threaded and unthreaded systems reveals an effective role of encapsulation in reducing aggregation and exciton migration for the rotaxanes with respect to the dumbbells, thus leading to higher PL quantum efficiency and preserved single‐molecule photophysics for longer times after excitation in the threaded oligomers.     

A test and calibration strategy for adjustable RF circuits

A test and calibration strategy suitable for adjustable RF circuits is presented in this paper. Certain performance-affecting circuit elements are designed to be digitally controllable, providing the capability to adjust the performance characteristics of a circuit’s instance around their post-fabrication values, throughout a set of discrete states of operation. The alternate test methodology is adopted for test and calibration and a set of optimally selected test observables is used to develop regression models for the prediction of the circuit’s performance characteristics in every state of operation. In the test phase, measurements of the test observables are obtained from a subset of the circuit’s states. The processing of these observables provides accurate prediction of the RF circuit’s performance characteristics in all available states and enables the discrimination of defect-free from defective circuits. The latter is further accomplished by the exploitation of an extended superset of the test observables, the use of which intends to maximize fault coverage. Moreover, the predicted performance characteristics are also used to examine compliance with the specifications and to allow calibration of the RF circuit by identifying the appropriate state of operation at which all specifications are met and, consequently, by forcing the circuit to operate in this specific state. The efficiency of the proposed technique has been validated by its application to a typical differential RF Mixer designed in a 0.18 μm CMOS technology. Simulation results have been obtained and assessed.     

Radio-over-free space optical space division multiplexing system using 3-core photonic crystal fiber mode group multiplexers

Wireless Networks - Radio over free space optics (Ro-FSO) systems have previously relied on the signal intensity, wavelength and polarization for multiplexing data streams in...     

Micro- and Nano-scale Measurement of the Thermophysical Properties of Polymeric Materials Using Atomic Force Microscopy

To realize the benefits and optimize the performance of micro- and nano-structured materials and thin films, designers need to understand and thus be able to characterize their thermal, thermophysical, and thermomechanical properties on appropriate length scales. This paper describes the determination of glass-transition temperatures of polymers on the micro-scale, obtained from contact force–distance curves for poly(methyl methacrylate) and poly(vinyl acetate) measured using an atomic force microscope (AFM). Measurements were made using a standard AFM tip where thin films were heated using a temperature controlled hot stage and by using a scanning thermal microscopy (SThM) probe. The latter was used either with the hot stage or with the SThM probe providing a localized heating source via Joule heating. Differences in the glass-transition temperature measured using the hot stage and Joule heating were apparent and considered to be due to heat transfer effects between the probe, specimen, and surroundings. Gradients of force–distance curves, pull-off and snap-in forces, and adhesion energy were obtained. The results suggest that the onset of changes in the material’s mechanical properties at the glass transition was found to be dependent on the mechanical property measured, with pull-off force values changing at lower temperatures than the snap-in force and adhesion energy.     

Profiling selected phytochemicals and nutrients in different tissues of the multipurpose tree Moringa oleifera L., grown in Ghana

The purpose of this new study was to determine the types and levels of major phytochemicals (non-nutrients) and nutrients in the different tissues from vegetative and flowering Moringa oleifera L. an important multipurpose crop. Rhamnose and acetyl-rhamnose-substituted glucosinolates were found in all of the M. oleifera tissues with different profiles depending on the tissue. In addition the tissues of M. oleifera had a relatively complex flavonoid profile consisting of glucosides, rutinosides, malonylglucosides and traces of acetylglucosides of kaempferol, quercetin and isorhamnetin. Fatty acid profiling of the different tissues showed that leaves were rich in palmitic (16:0) and linolenic (18:3) acid whereas seeds were predominated by oleic acid (18:1). Roots were rich in palmitic and oleic acid, whereas stems and twigs predominately contained palmitic acid. Potassium, magnesium and calcium were the predominant minerals in all of the tissues. Low levels of selenium were detected only in whole seeds.     

Toxic metals (Hg, Cd, and Pb) in fishery products imported into Italy: suitability for human consumption

Mercury, cadmium, and lead concentrations were determined in various fishery products (fishes, cephalopod molluscs, and crustaceans) imported into Italy from many European and non-European coastal countries. Considerable differences were found in the concentrations of these metals among the products tested. The highest mean Hg concentration was found in fishes (0.21 μg g(-1) wet weight), whereas cephalopods had the highest mean Cd concentration (0.35 μg g(-1) wet weight). Swordfish (0.80 μg g(-1) wet weight), longtail tuna (0.53 μg g(-1) wet weight), and thornback ray (0.52 μg g(-1) wet weight) had the highest concentrations of Hg, whereas maximum Cd concentrations were found in samples of common cuttlefish (0.85 μg g(-1) wet weight) and common octopus (0.64 μg g(-1) wet weight). The majority of the samples analyzed were in compliance with European Union legislation, except for a few cases. The calculated mean weekly intakes of Hg, Cd, and Pb through consumption of the fishery products tested were all below the legislated respective provisional tolerable weekly intakes. In general, the samples analyzed were considered safe to eat with regard to the metal concentrations found and the allowable intakes based on legislation. Nevertheless, the consumption of some species may be of significant importance for consumer health.     

Persistent organic pollutants in farmed European sea bass (Dicentrarchus labrax,Linnaeus, 1758) from Sicily (Italy)

Farmed European sea bass (Dicentrarchus labrax, Linnaeus, 1758) were collected during 2016 from one Sicilian fish farm that uses two different rearing systems – sea cage and concrete tank – for determination of polychlorinated biphenyls (PCB), organochlorine pesticides (OCP) and polycyclic aromatic hydrocarbons (PAH) residues by HRGC-MS/MS. Moreover, commercial feed was analysed. This study aimed to determine whether the different rearing systems affect the concentration of these compounds, and to assess the safety of cultured fish. PCBs represent the pollutants with the highest concentration; in particular, PCB138 and 153 have the highest concentration in almost all samples. Among OCPs, only 4,4′-DDE, 4,4′-DDD and 4,4′-DDT residues have been detected. Concerning PAHs, only fluorene and phenanthrene were detected, in both rearing systems. Although some residues of organic pollutants were found in the analysed samples, they were always below the MRLs, so the results suggest that farmed sea bass are safe for human consumption.