A method for the detection of alcohol vapours based on optical sensing of magnesium 5,10,15,20-tetraphenyl porphyrin thin film by an optical spectrometer and principal component analysis

In this work we have proposed a method for the detection of alcohol vapours, i.e. methanol, ethanol and isopropanol, based on the optical sensing response of magnesium 5,10,15,20-tetraphenyl porphyrin (MgTPP) thin films, as measured by optical spectrometry with the assistance of chemometric analysis. We have implemented a scheme which allows a laboratory UV–vis spectrometer to act as a so-called “electronic nose” with very little modification. MgTPP thin films were prepared by a spin coating technique, using chloroform as the solvent, and then subjected to thermal annealing at 280 °C in an argon atmosphere. These MgTPP optical gas sensors presented significant responses with methanol compared to ethanol and isopropanol, based on the dynamic flow of alcohol vapours at the same mol% of alcohol concentration. Density functional theory (DFT) calculations were performed to model the underlying mechanism of this selectivity. The performance of the optical gas sensors was optimised by varying the fabrication parameters. It is hoped that the MgTPP thin film together with an off-the-shelf optical spectrometer and a simple chemometrics algorithm can be a valuable tool for the analysis of alcoholic content in the beverage industry.     

Einstein–Podolski–Rosen paradox,non-commuting operator,complete wavefunction and entanglement

Einstein, Podolski and Rosen (EPR) have shown that any wavefunction (subject to the Schrödinger equation) can describe the physical reality completely, and any two observables associated with two non-commuting operators can have simultaneous reality. In contrast, quantum theory claims that the wavefunction can capture the physical reality completely, and the physical quantities associated with two non-commuting operators cannot have simultaneous reality. The above contradiction is known as the EPR paradox. Here, we unambiguously expose that there is a hidden assumption made by EPR, which gives rise to this famous paradox. Putting the assumption right this time leads us not to the paradox, but only reinforces the correctness of the quantum theory. However, it is shown here that the entanglement phenomenon between two physically separated particles (they were entangled prior to separation) can only be proven to exist with a ‘proper’ measurement.     

25-原子金纳米球和纳米棒催化性能的比较(英文)

The catalytic properties of two nanocluster catalysts with atomically precisely known structures,icosahedral two-shelled Au25(SC2H4Ph) 18 nanospheres and biicosahedral Au25(PPh3) 10(SC2H4Ph) 5Cl2 nanorods,were compared. Their catalytic performance in the two reactions of the selective oxidation of styrene and chemoselective hydrogenation of α,β-unsaturated benzalacetone was investigated. The catalytic activities of icosahedral Au25(SC2H4Ph) 18 nanospheres were superior to those of the bi-icosahedral Au25(PP...     

Controlled density patterning of tolylterpyridine-tagged oligonucleotides

An efficient surface anchoring strategy of tolylterpyridine-tagged DNA single strands (ssDNA-ttpy) synthesized on gold electrodes is reported. The method is based on exchange reactions between Fe(II)bis-terpyridine complexed SAMs and ssDNA-ttpy, and allows efficient hybrydization of the cDNA strands. Moreover, by using low-current focused ion beam lithography, micropatterned arrays are obtained, homogeneously covered with ssDNA-ttpy. The surface adsorption kinetics of ssDNA-ttpy, as well as its hybridization efficiency, was monitored by in situ quartz crystal microbalance with dissipation monitoring (QCM-D) technique. The effective confinement of the ssDNA-ttpy at the micrometer level has been monitored by time of flight secondary ion mass spectrometry (ToF-SIMS) and ellipsometric surface imaging experiments, providing laterally resolved chemical and topographic mapping.     

Oxidation of thiosulfate by manganese(III) and nickel(III) complexes: A kinetic and mechanistic investigation

The kinetics of the oxidation of thiosulfate ion by [Mn(Y)]^? (H₄Y = trans-cyclohezane-1,2-dimine-N,N,N′,N′-tetraacetic acid) and [Ni(L¹)]²⁺ (HL¹ = 15-amino-3-methyl-4,7,10,13-tetraazapentadec-3-en-2-one oxime) have been investigated at 20.0, 30.0, and 40.0°C in aqueous solution and found to follow the general rate law ?d/dt [complex] = k_ox[S₂O₃^2?] [complex]. The large negative entropy (ΔS?) of activation for the reactions and the results of Marcus calculation provide support for inner-sphere mechanism to be operative. © 1995 John Wiley & Sons, Inc.     

Kinetics of electron transfer reactions of manganese (III) complexes of trans-cyclohexane-1,2-diamine,-NNN′N′-tetraacetic acid and 2,2′-bipyridyl with ascorbic acid in aqueous acid media

The kinetics of the reactions of manganese(III) complexes of trans-cyclohexane-1,2-diamine-NNN′N′-tetraacetic acid (H₄cydta) and 2,2′-bipyridyl (bpy) have been investigated in the acid ranges [H⁺] = 1.00 ×10⁻⁵ − 3.16 × 10⁻³ M and [H⁺] = 0.10 − 1.00 M, respectively, at different temperatures and at a constant ionic strength. Both the molecular and mono-anionic forms of ascorbic acid have been found to be reactive in the experimental acid ranges. The monoanionic species has been found to be more reactive than the molecular form. Attempts have been made to correlate the kinetic results in terms of the Marcus relationship for outer-sphere electron transfer reaction. Differences between the calculated rates (k_0.8) and experimental rates (k) by approximately four and seven orders of magnitude (k_0.8≪ k) suggest an innersphere pathway for the reaction of Mn(cydta)(H₂O)⁻. Inner-sphere reaction is also believed to be operative for the other reaction. The activation parameters have been evaluated and compared with other reported systems.     

Competing magnetic interactions in a dinuclear Ni(II) complex: antiferromagnetic O-H...O moiety and ferromagnetic N3- ligand

Synthesis, structural characteristics, magnetic studies and DFT calculations in Ni(II) dinuclear complexes containing two bridging N3- and an O-H...O linkage reveal the existence of ferromagnetic interactions between Ni(II) centers via N3- ligands and antiferromagnetic interactions through the H-bonded moiety. The overall magnetic behavior of the system depends on the delicate balance between these two competing interactions.     

Low energy o-Ps–o-Ps elastic scattering using a simple model

A simple model is employed to investigate o-Ps–o-Ps scattering at low energies. This model contains the effect of exchange explicitly and a model long range potential in the framework of static-exchange model. These two physical features are of key importance in Ps-Ps (atom-atom) scattering system. S-wave triplet-triplet and singlet-singlet scattering lengths and corresponding phase shifts up to the incident momentum k=0.5 a.u. are in excellent agreement with those yielded by most elaborate and theoretically sound predictions.