12C18O2: High-resolution emission spectra in the 4.5-μm region rovibrational transitions 0v′2v3 → 0v′2(v3 − 1), v2 = l

Emission spectra of gaseous mixtures involving isotopic species of CO₂ excited by a dc discharge were recorded under Doppler-limited resolution, using a high-information Fourier Transform Interferometer, in the region 4–5 μm. In this paper are given the results concerning 34 vibrational transitions (Δv₃ = 1), for ¹²C¹⁸O₂. The band centers and the spectroscopic constants for the 39 vibrational levels involved are reported. They reproduce more than 1000 experimental wavenumbers with a RMS of the order of 2 × 10^?5 cm^?1 for the best vibrational transition and less than 3 × 10^?4 cm^?1 for most of the others. From a weighted simultaneous fit of all the experimental wavenumbers belonging to the Σ-Σ transitions, a set of molecular parameters was computed. A good reproduction of the experimental wavenumbers was obtained for all the vibrational transitions except those involving the level v₃ = 9, our conclusion being that a local vibrational perturbation exists for this level.     

Vibrational luminescence of CO2 excited by dc discharge: Rotational and vibrational molecular constants

High-resolution measurements have been performed on 33 emission bands of the carbon dioxide molecule from 4.2 to 4.7 μm. Accurate values of the vibrational and rotational constants of 39 vibration levels were obtained. Molecular constants were calculated from observed wavenumbers.     

现代无线电话的电源管理:满足子系统的设计需求

电源管理的发展趋势,正由产品要加入更多功能的需求所推动。集成无线设备,例如智能电话便结合了多种功能于一身,包括蜂窝电话、PDA、数码相机、音乐播放器GPS,这会进一步突破技术的界限,而电源管理也不例外。本文将讨论当今最先进蜂窝电话设计所使用最新的电源管理产品。智能电话子系统先进的智能电话系统(配有手机和AC适配器/充电器)由五个主要电路板组成:显示板、基带主板、键盘板、锂离子电池板及AC适配器板,还为数码相机、蓝牙或其它功能提供附加模块。相应地,电源管理也分成五个子系统。?显示板上的LED驱动器IC及四个白光LED;?…     

Five-Dimensional Bieberbach Groups with Holonomy Group Z2⊕Z2

In this paper we determine all five-dimensional compact flat Riemannian manifolds with holonomy group Z ₂Z ₂. The classification is achieved by classifying their fundamental groups up to isomorphism. The Betti numbers of all these manifolds are also computed.     

Peptide mapping through the coupling of capillary electrophoresis and high-performance liquid chromatography: map prediction of the tryptic digest of myoglobin.

The tryptic map of horse myoglobin was analysed through capillary electrophoresis using capillaries modified by a monolayer of acrylamide. The results were reproducible and the map was obtained in less than 30 min from ca. 8 pmol of tryptic digest. The peptide identification was performed using peptides previously identified by high-performance liquid chromatography. The peak areas measured using the two techniques are closely related, and the comparison of elution and migration times shows that the two techniques provide different maps. Furthermore, using the semiempirical relationship suggested by Grossman et al. [Anal. Biochem., 179 (1989) 28], which links the electrophoretic mobility to the charge of the peptide and its number of amino acids, a good agreement between predicted and experimental mobilities was observed.     

Investigating the properties of supported vesicular layers on titanium dioxide by quartz crystal microbalance with dissipation measurements

Adsorption of phospholipid vesicles on titanium dioxide was studied by a combination of quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy techniques. Vesicle size, concentration in solution, and bilayer composition were systematically varied. A strong dependence of the QCM-D response (magnitude of the frequency and dissipation factor shifts) on the vesicle concentration in solution was observed. QCM-D data were compared with a linear viscoelastic model based on the Voight element to determine layer thickness, density, elastic modulus, and viscosity. Based on the results of this comparison, it is proposed that (i) layer thickness and density, as sensed by QCM-D, saturate much earlier (in time) than the actual surface coverage of the vesicles (number of vesicles per unit area); (ii) changes in surface coverage that occur after the density and thickness, as sensed by QCM-D, have saturated, are interpreted by the model as changes in the layer's viscoelastic properties. This is caused by the replacement of the viscous media (water) between the vesicles by viscoelastic media of similar density (vesicles); (iii) viscoelastic properties of layers formed at different vesicle concentrations differ significantly, while the vesicle surface coverage in those layers does not. Based on the comparison between the atomic force microscopy images and QCM-D data acquired at various vesicle concentrations it is proposed that QCM-D response is not directly related to the surface coverage of the vesicles.     

The migratory insertion of carbon monoxide and methyl isocyanide into zirconium–carbon and titanium–carbon bonds anchored to a calix[4]arene moiety: a dynamical density functional study

The energetics and reaction mechanism of the migratory insertion of carbon monoxide and methyl isocyanide into the zirconium–carbon and titanium–carbon bonds in [calix[4](OMe)₂(O)₂–M–Me₂], (M=Zr, Ti), have been investigated by combining static and dynamic density functional calculations. Two steps have been characterized: the coordination of the incoming nucleophilic moiety leading to relatively stable facial adducts; its subsequent insertion into the M–C bond, leading to ²-bound acyl or iminoacyl complexes, providing a rationale for the different behavior of CO and MeNC towards both insertion and deinsertion reactions. Our results indicate that the rate-determining step for the overall MeNC insertion into the M–C bond is its coordination to the electron-deficient metal center, with the titanium system featuring a higher energy barrier (12.7 versus 5.5 kcal mol^–1). Ab initio molecular dynamics simulations have been performed on the Zr system by means of the Car–Parrinello method, to study the hitherto inaccessible mechanistic features of the insertion reactions.Contribution to the Björn Roos Honorary Issue     

Capillary electrophoretic study of the binding of zinc(II) ion to bacitracin A1 in water-2,2,2-trifluoroethanol

Binding of Zn(2+) to bacitracin A(1) was studied by capillary electrophoresis in water/2,2,2-trifluoroethanol (70/30 v/v) at different apparent pH values in order to estimate the association constant of metal, the acidic dissociation constants and the Stokes radii of both free and bounded peptide in apolar environment. The Stokes radii of the free peptide species were compared with those in aqueous solution, as obtained in a recent study performed by our group, indicating that apolar environment stabilizes bacitracin A(1) in a conformational structure with the lateral chain of apolar amino acids exposed on the external surface. This conformation of the macrocyclic dodecapeptide is ready to interact with Zn(2+) ion, as pointed out by the strong increase of the association constant measured in water/2,2,2-trifluoroethanol with respect to the value obtained in aqueous solution. In addition, whereas Zn(2+) ion binding in aqueous solution provides a sensible reduction of peptide Stokes radius, no sensible variations following to ion binding were observed in hydro-organic solution. The present results suggest that the apolar environment, rather than the metal ion binding, could be responsible for the conformational transition that brings bacitracin A(1) towards its biologically active structure.*     

A 2D layered spin crossover complex constructed by NH...Cl- hydrogen bonds: [FeIIH3LMe]Cl.I3 (H3LMe = tris[2-(((2-methylimidazoyl-4-yl)methylidene)amino)ethyl]amine

A 2D layered spin crossover complex, [FeIIH3L(Me)]Cl.I3, has been synthesized from the reaction of FeIIICl3, a tripod ligand (H3LMe = tris[2-(((2-methylimidazoyl-4-yl)methylidene)amino)ethyl]amine), and NaI in methanol. The compound showed an abrupt spin transition between the HS (S = 2) and LS (S = 0) states at T(1/2) = 110 K without hysteresis. The crystal structures of the HS and LS states were determined at 180 and 90 K. A 2D layered structure is composed of NH...Cl- hydrogen bonds between the Cl- ion and three neighboring imidazole groups of [FeIIH3LMe]2+. The green light irradiation at 5 K induced the LIESST effect, and the thermal relaxation process from the HS to LS state showed a sigmoid curve at T > 55 K.