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The precise location of gastric and colorectal tumors is of paramount importance for the oncological surgeon as it dictates the limits of resection and the extent of lymphadenectomy. However, this task proves sometimes to be very challenging, especially in the laparoscopic setting when the tumors are small, have a soft texture, and do not invade the serosa. In this view, our research team has developed a new instrument adapted to minimally-invasive surgery, and manipulated solely by the operating surgeon which has the potential to locate precisely tumors of the digestive tract. It consists of an inductive proximity sensor and an electronic block encapsulated into an autoclavable stainless-steel cage that works in tandem with an endoscopic hemostatic clip whose structure was modified to increase detectability. By scanning the serosal side of the colon or stomach, the instrument is capable to accurately pinpoint the location of the clip placed previously during diagnostic endoscopy on the normal bowel mucosa, adjacent to the tumor. In the current in-vivo experiments performed on large animals, the modified clips were transported without difficulties to the point of interest and attached to the mucosa of the bowel. Using a laparoscopic approach, the detection rate of this system reached 65% when the sensor scanned the bowel at a speed of 0.3 cm/s, and applying slight pressure on the serosa. This value increased to 95% when the sensor was guided directly on the point of clip attachment. The detection rate dropped sharply when the scanning speed exceeded 1 cm/s and when the sensor-clip distance exceeded the cut-off value of 3 mm. In conclusion, the proposed detection system demonstrated its potential to offer a swift and convenient solution for the digestive laparoscopic surgeons, however its detection range still needs to be improved to render it useful for the clinical setting. [ABSTRACT FROM AUTHOR]

We present in this work a fabrication chain of an electrochemical sensor platform based on detection of Cr 3+ and Co 2+ metallic ions species. Through molecular beam epitaxy (MBE) technique, a high quality Au (111) thin film was firstly fabricated in ultra-high vacuum (UHV) conditions, and used as support for chemical SAMs functionalization with 1,4-dithiothreitol (DTT) spacers. On the formed hybrid surface/linker structures, we employed Dip Pen Nanolithography (DPN) for patterning various templates of Cr 3+ and Co 2+ metallic ion species. Coated AFM tips with metallic molecular inks were used to fabricate different paths on the Au substrate, offering a unique functional design complexity. By varying the tip speed and/or dwell time, micro-nano-scale templates of both species were patterned in the form of square, double-square, triangle and lines. A full control of molecular ink transport mechanisms during the drawing process was assured, succeeding the writing of Cr 3+ and Co 2+ metallic ions on Au film substrate. Surface topology analyzed by Lateral Force Microscopy demonstrated the chemical contrast of patterned species, being a clear indicative of DPN tracing paths. Molecular recognition of both Cr 3+ and Co 2+ metallic ions has been made by potentio-electrochemical impedance spectroscopy (PEIS) measurements. The Nyquist plots were compared and the equivalent circuits obtained in both conformations (Cr 3+/ DTT/Au, Co 2+/ DTT/Au) were discussed in the light of experimental parameters. [ABSTRACT FROM AUTHOR]

The molecular doping of graphene with π-stacked conjugated molecules has been widely studied during the last 10 years, both experimentally or using first-principle calculations, mainly with strongly acceptor or donor molecules. Macrocyclic metal complexes have been far less studied and their behavior on graphene is less clear-cut. The present density functional theory study of cobalt porphyrin and phthalocyanine adsorbed on monolayer or bilayer graphene allows to compare the outcomes of two models, either a finite-sized flake of graphene or an infinite 2D material using periodic calculations. The electronic structures yielded by both models are compared, with a focus on the density of states around the Fermi level. Apart from the crucial choice of calculation conditions, this investigation also shows that unlike strongly donating or accepting organic dopants, these macrocycles do not induce a significant doping of the graphene sheet and that a finite size model of graphene flake may be confidently used for most modeling purposes. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Correlations between DFT and experimental measurements on Zn and Ni chiral meso-(α,β-unsaturated)- porphyrins were performed using Kohn-Sham methodology. The exchange-correlation Becke88-Perdew86 functional was used in conjunction with double-zeta Slater basis sets. An accurate description of the electronic processes depending on the metal ion (Zn, Ni) or ligand (perilaldehyde and myrtenal) was made, confirming experimental results in terms of structural and electronic modifications. Moreover, this theoretical study provides a stronger knowledge and interpretation of the dynamical conformational features of the free base, Zn and Ni structures. Fundamental links between the central metallic atom and distortions of the porphyrinic core and ligands were demonstrated, in agreement with experimental data. We observed that the core in ZnPeriP and ZnMyrtP species is almost flat, in comparison with the Ni porphyrinic core, which appeared much more distorted. The type of distortion differs between PeriP and MyrtP ligands, with a combined saddled-ruffled characteristic with the former and a pronounced ruffled twisting for the latter. Finally, conformational energy barriers were extracted by spinning one of the arms in steps of 20° in a 360° dihedral angle. The resulted conformational barriers for NiPeriP or NiMyrtP are lower in energy than for ZnPeriP or ZnMyrtP, in agreement with experimental data. [ABSTRACT FROM AUTHOR]

Abstract: Absorption spectra of PTCDI (3,4,9,10-perylene-tetracarboxylic-diimide) have been investigated in chloroform, N,N′-dimethylformamide (DMF) and dimethylsulfoxide (DMSO). While no signature of assembled PTCDI molecules is observed in chloroform solution, distinct bands assigned to their aggregation have been identified in DMF and DMSO solutions. PTCDI monomers show very similar absorption patterns in chloroform and DMSO solutions. Experimental data, including the vibronic structure of the absorption spectra were explained based on the Franck–Condon approximation and quantum chemical results obtained at PBE0-DCP/6-31+G(d,p) level of theory. Geometry optimization of the first excited state leads to a nice agreement between the calculated adiabatic transition energies and experimental data. [Copyright &y& Elsevier]

• Fabrication of high quality Ag films using MBE deposition technique. • Surfaces shape, roughness and growth profiles were analyzed by using SEM/EDX and AFM. • Surface topography was highlighted depending on the Ag films thicknesses. • Nanolithography of L-methionine amino acid on the Ag films was performed by DPN. The present work explore the fabrication of four silver thin films with controlled thicknesses of 30 nm, 60 nm, 90 nm and 120 nm, by using ultra-high vacuum (UHV) molecular beam epitaxy (MBE) technique. The peculiarities of their transformations depending on substrate quality, roughness and shape profile types were analyzed by Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and Atomic Force Microscopy (AFM) scanning approaches. Topographical characteristics and structure modifications were highlighted depending on the deposition thicknesses. Within the increase of silver layers, Ag particles started to form a more uniform, clustered layer on the glass substrate. The improved regularity of Ag particles inside clusters defines better the cluster profiles, emphasizing a preferred orientation and arrangement of Ag particles. For the thicker layers of 90 nm and 120 nm, a well-ordered particles arrangement is present in a much higher amount, unifying the clusters with preferred regular orientations. This phenomenon has conducted to the formation of cluster islands, thus increasing the surface roughness. The reactivity of Ag thin films toward L-methionine amino acid was explored by Dip Pen Nanolithography (DPN). A clear dependence between the formation of distinct surface properties and the ease of direct-write patterning was demonstrated. An optimum linkage preference of molecular L-methionine for the most flat surface of 30 nm growth has been emphasized, while for the other substrates the writing process is critically affected by the surface roughness. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: We describe a method to improve the yield and the kinetics of the difficult syntheses of α,β-unsaturated porphyrins, which enabled us to obtain a new chiral porphyrin derived from (S)-(−)-perillaldehyde in a 6% yield. Variable temperature NMR experiments on the free base, the zinc(II) and the nickel(II) complexes showed that two distinct and consecutive dynamic processes linked with the meso substituents rotation occurred. These processes can be analyzed as an evolution of the conformer composition upon temperature change. Higher values are found for the free energies of rotation of the substituent (measured by variable temperature 1H NMR) compared to those of other equivalent porphyrins like meso-tetraphenyl porphyrin or meso-tetracyclohexyl porphyrin. [Copyright &y& Elsevier]

• Hierarchical approach projection that employs rectangular shapes for the novel grids design. • Predictions of current distribution by a numerical algorithm across the electrodes grid surface. • SoH prediction by electrochemical impedance spectroscopy technique. • An improved lifetime performance was obtained, compared to industrial electrodes. • We reduced the lead quantity in the manufacturing process by changing their configuration. A variety of technological approaches of lead-acid batteries have been employed during the last decades, within distinguished fabrication features of electrode grid composition, electrolyte additives, or oxide paste additives embodiment. We proposed in this study, a particular path for improving the efficiency of positive grids by developing two novel geometry designs of lead-acid battery metallic grids. Our projection is based on a hierarchical approach that employed exclusively rectangular shapes for the structural configuration of grids. The intensity of current distribution was firstly evaluated by a numerical algorithm across the electrodes grid surface, thus allowing measuring the propagation of the electric charge emitted from each point inside of the grid. The novel fabricated prototypes were investigated by electrochemical impedance spectroscopy, following a controlled aging procedure. Two distinct parameters were investigated for evaluation of batteries lifetime: i) a time-dependent analysis of Constant Phase Element – Q parameter at 75% SoC partially discharged, and ii) the resonance frequency of the circuit. To confirm our improvements, we compared the data with the ones of an industrial grid model. An increment of battery lifetime was obtained for one prototype, with an estimation growth of 25% - 28% over the usual industrial electrode, while for the later a slightly improved lifetime efficiency of about 10% was resulted. Fig.1. Left: Typical distribution of electric potential in the grid during discharge (Indicated: 20 equipotential contour lines, respectively the three areas used as a guide for grid design, defined according to the density of equipotential field lines. Right: representation of the gradients in the plate at discharge; the regions with "homogenous" gradients are also represented. Colors are used to indicate the qualitative distributions of absolute value for gradients from small values (bottom of the plate) to large ones at the top. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Location of small gastric or colorectal tumors during a laparoscopic procedure is often imprecise and can be misleading. There is a real need for a compatible and straightforward tool that can be used intraoperatively to help the surgeon in this regard. We emphasize in the present work on the fabrication of a new and innovative inductive proximity switch architecture, fully compatible with laparoscopic surgery and with direct application in precise localisation of bowel tumors. An electromagnetic detection probe optimized for laparoscopic surgery and preconditioned for sterilisation was designed and constructed. Various metallic markers designed to be attached to the gastrointestinal mucosa were used for detection by the probe, from standard endoscopic and laparoscopic haemostatic clips to other custom made tags. Experiments were performed in dry and wet-lab experimental laboratory environment using ex-vivo segments of calf's small bowel and colonic surgical specimens from human patients. The dry-lab detection range varied considerably depending on the metallic component of the tags, from 0.5 mm for the endoscopic hemostatic clip to 3.5 mm for the 0.9 mm thickness stainless-steel custom tags. The latter was actually detectable from the serosal side of the fresh colonic surgical specimens in 85% of the attempts if the scanned area was less than 150 cm2 and less than 2 mm of fat was interposed between the probe and the bowel. The newly designed system has the potential to discover metallic tags attached to the bowel mucosa for precise intraoperative laparoscopic location of digestive tumors. Further work is in progress to increase the sensitivity and detection range of the system in order to make it fully compatible with the clinical use. • Innovative designed inductive proximity switch architecture. • Electromagnetic detection probe optimized and compatible with laparoscopic surgery. • New metallic markers with higher detection for sensor. • Detection range varies considerably depending on the metallic component of the tags. • Dry and wet-lab tests for both sensor and metallic tags. [ABSTRACT FROM AUTHOR]

This work explores a qualitative appraisal of lead acid battery electrodes by Electrochemical Impedance Spectroscopy. Lead acid cells behavior has been examined by gathering data of impedance modifications in distinct electrolyte volumes, from a full one to a battery filled at about 20% of the total volume of acid. Since the current between electrodes is inhomogeneous around the collector by varying the quantity of the electrolyte, we have associated numerical values of the elements in the battery equivalent circuit, to the homogeneity of the current in the electrodes. Theoretical considerations dealing with modeling, equivalent circuits and corresponding equations are provided. As a function of the electrolyte quantity, we investigated the dependence of the values for components of the Randle circuit. A particular attention has been devoted to constant phase element (CPE) peculiarities, as this parameter was found essential for a good quality fit over an extended range of batteries. The stability depending on current homogeneity at a certain battery state of charge was analysed in order to assess the effect of electrolyte volumes, and thereby to provide new quality requirements for improvement of lead-acid battery performance. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the vibrational properties of pentagonal and hexagonal single walled silicon nanotubes by using DFT and the frozen phonons method. The phononic band structure and the vibrational density of states are reported. The stability of each structure is discussed based on these results. We investigate the influence of isotopic substitutions upon the vibrational density of states for the two types of nanotubes. Finally, we show that the model of vibrational Hamiltonian in a diatomic chain can be used to give a qualitative description of the relation between the amount of isotopically substituted layers in the nanotube and their influence upon the vibrational density of states. [Copyright &y& Elsevier]

The binding effects of Mn2+ and Ca2+ ions on the vibrational properties of adenine-thymine (AT) base pairs have been investigated using density functional theory. The metallic atoms were coordinated to N3 and N7 atoms of adenine, respectively. We analyze the geometric properties of different metal-AT base pairs structures, as well as the vibrational bands that can be used to detect the presence of metallic ions. In particular we have found that strong vibrational amplitudes of metallic atoms are expected for the vibrational bands in the range between 400-500 cm-1. Also, we point out the effects of cations binding over a series of selected modes, corresponding to experimental data, providing values for the resulting shifts for each of these vibrational bands. [ABSTRACT FROM AUTHOR]

The binding effects of Mg, Ca, and Cu ions on the vibrational properties of guanine-cytosine base pairs have been performed using density functional theory investigations. Both Watson-Crick and Hoogsteen configurations of the base pairs were investigated. In Watson-Crick configuration, the metal was coordinated at N7 atom of guanine, while in the case of Hoogsteen configuration, the coordination is at N3 atom of guanine. We have pointed out the geometric properties of the metal-GC base pairs structure, as well as the vibrational bands that can be used to detect the presence of metallic ions in the Watson-Crick and Hoogsteen GC structures. For the geometric models used by us, the vibrational amplitudes of metallic atoms were stronger for wavenumbers lower than 500 cm. This suggests that in the experimental studies on DNA the presence of the three metallic atoms (Mg, Ca, and Cu) can be explicitly detected at low frequencies. [ABSTRACT FROM AUTHOR]

The phosphorescent binuclear iridium(III) complexes tetrakis(2-phenylpyridine)μ-(2,2′:6′,2″-terpyridine-6,6″-dicarboxylic acid)diiridium (Ir1) and tetrakis(2-(2,4-difluorophenyl) pyridine))μ-(2,2′:6′,2″-terpyridine-6,6″-dicarboxylic acid)diiridium (Ir2) were synthesized in a straightforward manner and characterized using X-ray diffraction, NMR, UV-vis absorption, and emission spectroscopy. The complexes have similar solution structures in which the two iridium centers are equivalent. This is further confirmed by the solid state structure of Ir2. The newly reported complexes display intense luminescence in dichloromethane solutions with maxima at 538 (Ir1) and 477 nm (Ir2) at 298 K (496 and 468 nm at 77 K, respectively) and emission quantum yields reaching 18% for Ir1. The emission quantum yield for Ir1 is among the highest values reported for dinuclear iridium complexes. It shows only a 11% decrease with respect to the emission quantum yield reported for its mononuclear analogue, while the molar extinction coefficient is roughly doubled. This suggests that such architectures are of potential interest for the development of polymetallic assemblies showing improved optical properties. DFT and time-dependent-DFT calculations were performed on the ground and excited states of the complexes to provide insights into their structural, electronic, and photophysical properties. [ABSTRACT FROM AUTHOR]