Adsorption of carbon monoxide on the surfaces of polycrystalline transition metals and alloys: electron energy loss and ultraviolet photoelectron spectral studies1

Adsorption of CO has been investigated on the surfaces of polycrystalline transition metals as well as alloys by employing electron energy loss spectroscopy (eels) and ultraviolet photoelectron spectroscopy (ups). CO adsorbs on polycrystalline transition metal surfaces with a multiplicity of sites, each being associated with a characteristic CO stretching frequency; the relative intensities vary with temperature as well as coverage. Whilst at low temperatures (80- 120 K), low coordination sites are stabilized, the higher coordination sites are stabilized at higher temperatures (270-300 K). Adsorption on surfaces of polycrystalline alloys gives characteristic stretching frequencies due to the constituent metal sites. Alloying, however, causes a shift in the stretching frequencies, indicating the effect of the band structure on the nature of adsorption. The up spectra provide confirmatory evidence for the existence of separate metal sites in the alloys as well as for the high-temperature and low-temperature phases of adsorbed CO.

Urban energy fluxes in Helsinki and their high frequency spectral corrections

Inadvertent climate modification has led to an increase in urban temperatures compared to the surrounding rural area. The main reason for the temperature rise is the altered energy portioning of input net radiation to heat storage and sensible and latent heat fluxes in addition to the anthropogenic heat flux. The heat storage flux and anthropogenic heat flux have not yet been determined for Helsinki and they are not directly measurable. To the contrary, turbulent fluxes of sensible and latent heat in addition to net radiation can be measured, and the anthropogenic heat flux together with the heat storage flux can be solved as a residual. As a result, all inaccuracies in the determination of the energy balance components propagate to the residual term and special attention must be paid to the accurate determination of the components. One cause of error in the turbulent fluxes is the fluctuation attenuation at high frequencies which can be accounted for by high frequency spectral corrections. The aim of this study is twofold: to assess the relevance of high frequency corrections to water vapor fluxes and to assess the temporal variation of the energy fluxes. Turbulent fluxes of sensible and latent heat have been measured at SMEAR III station, Helsinki, since December 2005 using the eddy covariance technique. In addition, net radiation measurements have been ongoing since July 2007. The used calculation methods in this study consist of widely accepted eddy covariance data post processing methods in addition to Fourier and wavelet analysis. The high frequency spectral correction using the traditional transfer function method is highly dependent on relative humidity and has an 11% effect on the latent heat flux. This method is based on an assumption of spectral similarity which is shown not to be valid. A new correction method using wavelet analysis is thus initialized and it seems to account for the high frequency variation deficit. Anyhow, the resulting wavelet correction remains minimal in contrast to the traditional transfer function correction. The energy fluxes exhibit a behavior characteristic for urban environments: the energy input is channeled to sensible heat as latent heat flux is restricted by water availability. The monthly mean residual of the energy balance ranges from 30 Wm-2 in summer to -35 Wm-2 in winter meaning a heat storage to the ground during summer. Furthermore, the anthropogenic heat flux is approximated to be 50 Wm-2 during winter when residential heating is important.

A rational approach to the synthesis of one-dimensional acoustic filters

The velocity ratio algorithm developed from a heuristic study of transfer matrix multiplication has been employed to bring out the relative effects of the elements constituting a linear, one-dimensional acoustic filter, the overall dimensions of which are fixed, and synthesize a suitable straight-through configuration for a low-pass, wide-band, non-dissipative acoustic filter. The potential of the foregoing approach in applications to the rational design of practical acoustic filters such as automotive mufflers is indicated.

Infrared spectral assignments of methyl and ethyl xanthato complexes of nickel(II)

Assignments of the infrared frequencies of methyl and ethyl xanthato complexes of nickel(II) have been made with the aid of normal coordinate analyses. The assignments are discussed in relation to those in related molecules.

Infrared spectral assignments for transition metal thioxanthates

The i.r. frequencies of ethylthioxanthate complexes of some transition metals have been interpreted on the basis of normal coordinate treatments of the 1:1 molecular models. The band assignments are disscussed in comparison with those in closely related xanthate molecules.

Metal complexes of thiophene 2-thiocarboxamide. Proton and 13C NMR, IR and electronic spectral studies

The complexes of thiophene 2-thiocarboxamide (TTCA) with some metal chlorides and bromides [M = Ni(II), Zn(II), Cd(II), Hg(II) and Cu(I)] are described. Elemental analyses, magnetic susceptibilities and conductance studies, electronic, IR, proton and 13C magnetic resonance spectra are reported. The results suggest exclusive coordination of TTCA through the thiocarbonyl sulfur. The influence of the thiophene ring on the donor properties of the thioamide are discussed.

Synthesis, spectral and electrochemical properties of donor/acceptor substituted fluoroarylporphyrins

Spectroscopic and electrochemical redox properties of a series of fluorinated porphyrins bearing donor-acceptor groups and their Zn(II) and Cu(II) derivatives are presented. The magnitude of the ring reduction potentials and charge transfer properties derived from spectral data depend on the nature and position of the substituent(s), (nitro/dimethylamino) and the central metal ions.

Spectral and thermal data on polystyrene peroxide

Poly(styrene peroxide) has been prepared and characterized. Nuclear magnetlc resonance (NMR) spectra Of the polymer show the shift Of aliphatic protons. Differential scanning calorimetric (DSC) and differential thermal analysis (DTA) results show anexothermic peak around 110 OC which is characteristic of peroxide decomposition.

Spectral Tuning and Adaptation to Different Light Environments of Mysid Visual Pigments

In the present thesis, questions of spectral tuning, the relation of spectral and thermal properties of visual pigments, and evolutionary adaptation to different light environments were addressed using a group of small crustaceans of the genus Mysis as a model. The study was based on microspectrophotometric measurements of visual pigment absorbance spectra, electrophysiological measurements of spectral sensitivities of dark-adapted eyes, and sequencing of the opsin gene retrieved through PCR. The spectral properties were related to the spectral transmission of the respective light environments, as well as to the phylogentic histories of the species. The photoactivation energy (Ea) was estimated from temperature effects on spectral sensitivity in the long-wavelength range, and calculations were made for optimal quantum catch and optimal signal-to-noise ratio in the different light environments. The opsin amino acid sequences of spectrally characterized individuals were compared to find candidate residues for spectral tuning. The general purpose was to clarify to what extent and on what time scale adaptive evolution has driven the functional properties of (mysid) visual pigments towards optimal performance in different light environments. An ultimate goal was to find the molecular mechanisms underlying the spectral tuning and to understand the balance between evolutionary adaptation and molecular constraints. The totally consistent segregation of absorption maxima (λmax) into (shorter-wavelength) marine and (longer-wavelength) freshwater populations suggests that truly adaptive evolution is involved in tuning the visual pigment for optimal performance, driven by selection for high absolute visual sensitivity. On the other hand, the similarity in λmax and opsin sequence between several populations of freshwater M. relicta in spectrally different lakes highlights the limits to adaptation set by evolutionary history and time. A strong inverse correlation between Ea and λmax was found among all visual pigments studied in these respects, including those of M. relicta and 10 species of vertebrate pigments, and this was used to infer thermal noise. The conceptual signal-to-noise ratios thus calculated for pigments with different λmax in the Baltic Sea and Lake Pääjärvi light environments supported the notion that spectral adaptation works towards maximizing the signal-to-noise ratio rather than quantum catch as such. Judged by the shape of absorbance spectra, the visual pigments of all populations of M. relicta and M. salemaai used exclusively the A2 chromophore (3, 4-dehydroretinal). A comparison of amino acid substitutions between M. relicta and M. salemaai indicated that mysid shrimps have a small number of readily available tuning sites to shift between a shorter - and a longer -wavelength opsin. However, phylogenetic history seems to have prevented marine M. relicta from converting back to the (presumably) ancestral opsin form, and thus the more recent reinvention of marine spectral sensitivity has been accomplished by some other novel mechanism, yet to be found

Spectral Values

This series of drawings takes a diagrammatically creative approach to understanding the economic theories and personalities at the centre of the Global Financial Crisis. Mimicking the form of US currency, the work removes labels from common economic diagrams and portrays financial titans in repose as a way to express a personal and ambivalent experience of contemporary capitalism.

Ruthenium(II)-CO complexes of N-[(2-pyridyl)methyliden]-alpha(or beta)-aminonaphthalene: Synthesis, spectral studies, crystal structure, redox properties and DFT calculation

The characterization and properties of trans-(X)-[RuX2(CO)(2)(alpha/beta-NaiPy)] (1, 2) (alpha-NaiPy (a), beta-NaiPy (b); X = Cl (1), I (2)) are described in this work. The structures are confirmed by single crystal X-ray diffraction studies. Reaction of these compounds with Me3NO in MeCN has isolated monocarbonyl trans-(X)-RuX2(CO)(MeCN)(alpha/beta-NaiPy)] (3, 4). The complexes show intense emission properties. Quantum yields of 1 and 2 (phi= 0.02-0.08) are higher than 3 and 4 (phi = 0.006-0.015). Voltammogram shows higher Ru(III)/Ru(II) (1.3-1.5 V) potential of 1 and 2 than that of 3 and 4 (0.8-0.9 V) that may be due to coordination of two pi-acidic CO groups in former. The electronic spectra and redox properties of the complexes are compared with the results obtained by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) using polarizable continuum model (CPCM).

Jet Engine Health Signal Denoising Using Optimally Weighted Recursive Median Filters

The removal of noise and outliers from health signals is an important problem in jet engine health monitoring. Typically, health signals are time series of damage indicators, which can be sensor measurements or features derived from such measurements. Sharp or sudden changes in health signals can represent abrupt faults and long term deterioration in the system is typical of gradual faults. Simple linear filters tend to smooth out the sharp trend shifts in jet engine signals and are also not good for outlier removal. We propose new optimally designed nonlinear weighted recursive median filters for noise removal from typical health signals of jet engines. Signals for abrupt and gradual faults and with transient data are considered. Numerical results are obtained for a jet engine and show that preprocessing of health signals using the proposed filter significantly removes Gaussian noise and outliers and could therefore greatly improve the accuracy of diagnostic systems. [DOI: 10.1115/1.3200907].

Crystal structure of 3-acetylcoumarin-o-aminobenzoylhydrazone and synthesis, spectral and thermal studies of its transition metal complexes

Transition metal [Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)] complexes of a new Schiff base, 3-acetylcoumarin-o-aminobenzoylhydrazone were synthesized and characterized by elemental analyses, magnetic moments, conductivity measurements, spectral [Electronic, IR, H-1 and C-13 NMR, EPR] and thermal studies. The ligand crystallizes in the monoclinic system, space group P2(1)/n with a = 9.201(5), b = 16.596( 9), c = 11.517(6) angstrom, beta= 101.388(9)degrees, V = 1724.2 (17) angstrom(3) and Z = 4. Conductivity measurements indicated Mn(II) and Co(II) complexes to be 1 : 1 electrolytes whereas Ni(II), Cu(II), Zn(II) and Cd(II) complexes are non-electrolytes. Electronic spectra reveal that all the complexes possess four-coordinate geometry around the metal.

Synthesis, spectral characterization, in-vitro microbiological evaluation and cytotoxic activities of novel macrocyclic bis hydrazone

A macrocyclic hydrazone Schiff base was synthesized by reacting 1,4-dicarbonyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol and a series of metal complexes with this new Schiff base were synthesized by reaction with Co(II), Ni(II) and Cu(II) metal salts. The Schiff base and its complexes have been characterized by elemental analyses, IR, H-1 NMR, UV-vis, FAB mass, ESR spectra, fluorescence, thermal, magnetic and molar conductance data. The analytical data reveal that the Co(II), Ni(II) and Cu(II) complexes possess 2:1 metal-ligand ratios. All the complexes are non-electrolytes in DMF and DMSO due to their low molar conductance values. Infrared spectral data suggest that the hydrazone Schiff base behaves as a hexadentate ligand with NON NON donor sequence towards the metal ions. The ESR spectral data shows that the metal-ligand bond has considerable covalent character. The electrochemical behavior of the copper(II) complex was investigated by cyclic voltammetry. The Schiff base and its complexes have also been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Shigella dysentery, Micrococcus, Bacillus subtilis, Bacillus cereus and Pseudomonas aeruginosa) and antifungal activities (Aspergillus niger, Penicillium and Candida albicans) by MIC method. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties. (C) 2009 Elsevier Masson SAS. All rights reserved.