Search results for "circular"
showing 10 items of 856 documents
Silver based sensors from CD for chloride ions detection
2021
This preliminary work shows a new and innovative way to produce silver based electrodes from compact discs and its application towards the detection of chloride ions. A complete sensor was obtained from the compact discs with working, reference and counter electrode made of silver. Chloride ions were detected by exploiting the high affinity of silver with this anion to produce silver chloride. This electrochemical oxidation of silver can be monitored by using an electrochemical technique such as linear scan voltammetry. Indeed, during linear scan voltammetry the oxidation of silver to silver chloride lead to a peak current that increases linearly with chloride concentration. Using this tech…
DETECTION LIMITS FOR NATURAL CIRCULAR-DICHROISM OF CHIRAL COMPLEXES IN THE X-RAY RANGE
1993
Whereas both Magnetic Circular Dichroism and Faraday Rotation studies have been successfully carried out at the K-, L- and M-absorption edges of metal atoms in ferromagnetic systems, Natural optical activity of chiral complexes has not yet been detected quite unambiguously in the X-ray range. We review a number of theoretical arguments which confirm that the optical asymmetry factor gσ should be very small in the X-ray range for unoriented powdered samples, especially at the K-absorption edges. This stimulating challenge prompted us to start an intensive programme of measurements aimed at detecting natural circular dichroism in both the soft and “firm” X-ray ranges. Although some of our ex…
Halloysite nanotubes for efficient loading, stabilization and controlled release of insulin
2018
Hypothesis: Oral insulin administration is not actually effective due to insulin rapid degradation, inactivation and digestion by proteolytic enzymes which results in low bioavailability. Moreover insulin is poorly permeable and lack of lipophilicity. These limits can be overcome by the loading of protein in some nanostructured carrier such as halloysite nanotubes (HNTs). Experiments: Herein we propose an easy strategy to obtain HNT hybrid materials for the delivery of insulin. We report a detailed description on the thermal behavior and stability of insulin loaded and released from the HNTs hybrid by the combination of several techniques. Findings: Release experiments of insulin from the H…
DICHROISM IN ANGLE-RESOLVED PHOTOEMISSION FROM Pt(111)
2002
The angular dependence of the circular dichroism in photoemission from Pt(111) was investigated for excitation with VUV and soft X-ray radiation. VUV excitation was used to probe band structure and the circular dichroism for valence band emission. The measurements are compared to full relativistic single step photoemission calculations. XPS was used to investigate the circular dichroism in emission from the 4f core level. In this case, the dichroism is induced by photoelectron diffraction. First results from single step core level calculations are compared to the experimental observations.
Investigation of Co$_2$FeSi: The Heusler compound with Highest Curie Temperature and Magnetic Moment
2006
This work reports on structural and magnetic investigations of the Heusler compound Co$_2$FeSi. X-Ray diffraction and M\"o\ss bauer spectrometry indicate an ordered $L2_1$ structure. Magnetic measurements by means of X-ray magnetic circular dichroism and magnetometry revealed that this compound is, currently, the material with the highest magnetic moment ($6 \mu_B$) and Curie-temperature (1100K) in the classes of Heusler compounds as well as half-metallic ferromagnets.
Chirality and electronic structure of the thiolate-protected Au38 nanocluster.
2010
Structural, electronic, and optical properties of the thiolate-protected Au(38)(SR)(24) cluster are studied by density-functional theory computations (R = CH(3) and R = C(6)H(13)) and by powder X-ray crystallography (R = C(12)H(25)). A low-energy structure which can be written as Au(23)@(Au(SR)(2))(3)(Au(2)(SR)(3))(6) having a bi-icosahedral core and a chiral arrangement of the protecting gold-thiolate Au(x)(SR)(y) units yields an excellent match between the computed (for R = C(6)H(13)) and measured (for R = C(12)H(25)) powder X-ray diffraction function. We interpret in detail the electronic structure of the Au(23) core by using a particle-in-a-cylinder model. Although the alkane thiolate l…
Enhanced Surface Ligands Reactivity of Metal Clusters by Bulky Ligands for Controlling Optical and Chiral Properties.
2021
Surface ligands play critical roles in determining the surface properties of metal clusters. However, modulating the properties and controlling the surface structure of clusters through surface‐capping agent displacement remain a challenge. In this work, a silver cluster, [Ag 14 (SPh(CF 3 ) 2 ) 12 (PPh 3 ) 4 (DMF) 4 ] ( Ag 14 ‐DMF , where HSPh(CF 3 ) 2 is 3,5‐bis(trifluoromethyl)benzenethiol, PPh 3 is triphenylphosphine and DMF is N,N‐Dimethylformamide), with weakly coordinated DMF ligands on the surface silver sites, was synthesized by using a mixed ligands strategy (bulky thiolates, phosphines and small solvents). The as‐prepared Ag 14 ‐DMF is a racemic mixture of chiral molecules. Owing …
Co-Evolutionary Coupling via a Digital-bio Ecosystem – A Suggestion for a New R&D Model in the Digital Economy
2019
A solution to the critical problem of a dilemma between R&D expansion and productivity decline that a majority of information and communication technology (ICT) leaders have been confronting in the digital economy is expected. It can be expected by a spinoff from economic functionality-seeking GDP-based coevolution cycle to supra-functionality beyond an economic value-seeking uncaptured GDP-driven coevolution cycle. However, the transformation dynamism remains a black box. By means of numerical simulations based on empirical analyses of the development trajectories of global ICT leaders, focusing on Amazon and Finland, together with an intensive review of preceding analyses, this paper atte…
Efficient computation of the branching structure of an algebraic curve
2012
An efficient algorithm for computing the branching structure of a compact Riemann surface defined via an algebraic curve is presented. Generators of the fundamental group of the base of the ramified covering punctured at the discriminant points of the curve are constructed via a minimal spanning tree of the discriminant points. This leads to paths of minimal length between the points, which is important for a later stage where these paths are used as integration contours to compute periods of the surface. The branching structure of the surface is obtained by analytically continuing the roots of the equation defining the algebraic curve along the constructed generators of the fundamental gro…
Unavoidable sets and circular splicing languages
2017
Circular splicing systems are a formal model of a generative mechanism of circular words, inspired by a recombinant behaviour of circular DNA. They are defined by a finite alphabet A, an initial set I of circular words, and a set R of rules. In this paper, we focus on the still unknown relations between regular languages and circular splicing systems with a finite initial set and a finite set R of rules represented by a pair of letters ( ( 1 , 3 ) -CSSH systems). When R = A × A , it is known that the set of all words corresponding to the splicing language belongs to the class of pure unitary languages, introduced by Ehrenfeucht, Haussler, Rozenberg in 1983. They also provided a characteriza…