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Tremendous developments in mass spectrometry have taken place in the last 40 years. This holds for both the science and the instrumental revolutions in this field. In chemistry the research was heavily focused on organic molecules that upon electron ionization fragmented via complex mechanistic pathways as shown by isotopic labeling experiments. These studies, including ion structure determinations, were performed with use of double focusing mass spectrometers of both conventional and reversed geometry, and equipped with various types of metastable ion scanning and collision-induced dissociation techniques developed by physical and analytical chemists. Time-resolved mass spectrometry by use of the field ionization kinetics method, developed by physical chemists, was another powerful way to unravel details of unimolecular gas phase ion dissociations. Then the development of new ionization methods, such as desorption chemical ionization, field desorption, and fast atom bombardment permitted not only to analyze unvolatile, thermally labile and higher molecular weight compounds, but also to study their chemical behavior in the gas phase, initially with use of double focusing instruments and later on with multisector and hybrid mass spectrometers. These ionization methods also enabled to study organometallic compounds and increasingly the field of medium-sized to large biomolecules, the latter being exploded in the last decade by the development of electrospray- and matrix-assisted laser desorption ionization/time-of-flight mass spectrometry. Another area of research concerned the bimolecular chemistry of organic ions with organic molecules in the gas phase. Initially this was performed with use of among others drift-cell ion cyclotron resonance spectroscopy, that later on was replaced by the developed method of ion trapping and Fourier transform ion cyclotron resonance. Combination of the latter with the afore-mentioned ionization methods has shifted also in this case the research on organic molecules to organometallic/inorganic systems, and predominantly to biomolecules in the last decade. This invited review will describe the research efforts made by the author's group over the last 40 years together with some personal experiences during his career.

Computer simulation methods using orbital level of description only for a selected part of the larger systems are prone to the artificial charge leak to the parts which are described without orbitals. The absence of orbitals in one of the subsystems makes it impossible to impose explicitly the orthogonality condition. Using the subsystem formulation of density functional theory, it is shown that the absence of explicit condition of orthogonality between orbitals belonging to different subsystems, does not cause any breakdown of this type of description for the chosen intermolecular complexes (F(-)H(2)O and Li(+)H(2)O), for which a significant charge-leak problem could be a priori expected.

A product and time-resolved kinetic study on the reactivity of the radical cations generated from cyclopropyl(4-methoxyphenyl)phenylmethanol (1) and cyclopropyl[bis(4-methoxyphenyl)]methanol (2) has been carried out in aqueous solution. In acidic solution, 1*+ and 2*+ display very low reactivities toward fragmentation, consistent with the presence of groups at Calpha (aryl and cyclopropyl) that after Calpha-Cbeta bond cleavage would produce relatively unstable carbon-centered radicals. In basic solution, 1*+ and 2*+ display oxygen acidity, undergoing -OH-induced deprotonation from the alpha-OH group, leading to the corresponding 1,1-diarylalkoxyl radicals 1r* and 2r*, respectively, as directly observed by time-resolved spectroscopy. The product distributions observed in the reactions of 1*+ and 2*+ under these conditions (cyclopropyl phenyl ketone, cyclopropyl(4-methoxyphenyl) ketone, and 4-methoxybenzophenone from 1*+; cyclopropyl(4-methoxyphenyl) ketone and 4,4'-dimethoxybenzophenone from 2*+) have been rationalized in terms of a water-induced competition between O-neophyl shift and C-cyclopropyl beta-scission in the intermediate 1,1-diarylalkoxyl radicals 1r* and 2r*.

The phosphor LaInO3:Eu3+ exhibits, in addition to the weak orange-red emission of Eu3+, a broad blue emission whose origin formed the basis for the reinvestigation of luminescence of LaInO 3 and the analogous LaGaO3, well known host lattices for luminescent centers. The results are analyzed based on the luminescence observed for In3+ and Ga3+ in various host lattices. An attempt is made to understand the mechanism of the luminescence of d 10 ions In3+ and Ga3+. � 2005 Elsevier Ltd. All rights reserved.

A polymer based ion-sensor, selective for concentrating UO2 2 + and Th4+ ions is developed based on the use of a novel multi-donor ionophore, termed EHCOP (4,4-Bis-[bis-(2-ethyl-hexyl)-carbamoyl]-2-oxo-butyl}-phosphinic acid). The fabrication involves the stepwise chemical grafting of Amberlite XAD-16 resin beads with phosphinic acid and branched long alkyl chain amide moiety, to the desired EHCOP ligand. The grafted polymer exhibits phenomenal behavior in sensing both Th4+ and UO2 2 + from acidic and neutral conditions, with greater decontamination factor values. Moreover, in this sensor the only possible co-extractable lanthanides ions can also be selectively eliminated with 2 M HCl. The concentrated ions can be sequentially recovered by gradient elution, by first stripping off Th4+ ions with 2 M HCl-NaCl mixture, followed by 0.5 M (NH4)2CO3 for pure UO2 2 + fraction. The polymer's lowest sensing limit for UO2 2 + was 5 ?g L-1 and 10 ?g L-1 for Th4+. As the EHCOP moiety exhibits dual extraction property, it was successful in recovering uranium from seawater samples, with an RSD value of >3.9%. Based on the metal sorption capacity studies, the sensor material can be utilized both as an analytical and preparative column depending on the application. The response time involved for trace ion targeting was statically observed to be within 10 min and by dynamic mode with a flow rate of 14-16 mL min-1. The resin can be recycled as much as 15 cycles without any significant change in their sorption capacity. The chemical grafting was characterized by 13C CPMAS NMR, FT-NIR-FIR, and CHNP analyzer and the metal ion sensing was estimated by UV-vis and fluorescence spectroscopy. � 2006 Elsevier B.V. All rights reserved.

Electric dipole transition amplitudes of certain low-lying states of Pb + have been calculated using the relativistic coupled-cluster theory and compared with previous calculations. The role of electron correlation is found to be important. Some of the results we have obtained would be useful in estimating the size of the parity non-conserving amplitude for the 6p 2 P1/2 → 6p 2 P3/2 transition.

Positively charged ions, TenS4+ (n = 1-4), are detected in the laser desorption mass spectra of bulk TeS. Enhanced intensities for these species are seen only for the positive ions. The clusters are formed as a result of the ion chemistry in the gas phase as elemental mixtures of Te and S also give the same clusters, albeit with different intensity distribution. Computational studies confirm the structural and electronic stability of these species. Te3S4+ and Te4S4+ clusters are observed for the first time in the gas phase. � 2005 Elsevier B.V. All rights reserved.

We have used an electron beam ion trap to observe a visible line at 598.30(13) nm that corresponds to the 4d9 2D3/2–4d9 2D5/2 magnetic dipole transition within the ground state configuration of Xe9+. We have found no evidence to support the claim by others that a line near this position originates from Xe31+. The comparison of the measured wavelength with previous indirect experimental values, and the dependence of the line intensity on the electron beam energy, confirms the validity of the present identification. Our measured wavelength is in agreement with semiempirical Hartree-Fock calculations but shows a discrepancy with ab initio multiconfiguration Dirac-Fock calculations. We propose that the line may be useful as a diagnostic for extreme ultraviolet lithography light sources.

KcsA constitutes a potassium channel of known structure that shows both high conduction rates and selectivity among monovalent cations. A kinetic model for ion conduction through this channel that assumes rapid ion transport within the filter has recently been presented by Nelson. In a recent, brief communication, we used the model to provide preliminary explanations to the experimental current-voltage J-V and conductance-concentration g-S curves obtained for a series of monovalent ions (K(+),Tl(+), and Rb(+)). We did not assume rapid ion transport in the calculations, since ion transport within the selectivity filter could be rate limiting for ions other than native K(+). This previous work is now significantly extended to the following experimental problems. First, the outward rectification of the J-V curves in K(+) symmetrical solutions is analyzed using a generalized kinetic model. Second, the J-V and g-S curves for NH(4) (+) are obtained and compared with those of other ions (the NH(4) (+) J-V curve is qualitatively different from those of Rb(+) and Tl(+)). Third, the effects of Na(+) block on K(+) and Rb(+) currents through single KcsA channels are studied and the different blocking behavior is related to the values of the translocation rate constants characteristic of ion transport within the filter. Finally, the significantly decreased K(+) conductance caused by mutation of the wild-type channel is also explained in terms of this rate constant. In order to keep the number of model parameters to a minimum, we do not allow the electrical distance (an empirical parameter of kinetic models that controls the exponential voltage dependence of the dissociation rate) to vary with the ionic species. Without introducing the relatively high number of adjustable parameters of more comprehensive site-based models, we show that ion association to the filter is rate controlling at low concentrations, but ion dissociation from the filter and ion transport within the filter could limit conduction at high concentration. Although some experimental data from other authors were included to allow qualitative comparison with model calculations, the absolute values of the effective rate constants obtained are only tentative. However, the relative changes in these constants needed to explain qualitatively the experiments should be of significance.

Photolysis of the cryptand 1, bearing an intraannular azido substituent, results in a complex photochemistry. Low-temperature photolysis yields the triplet nitrene 32, which has been characterized by EPR spectroscopy. Small differences in ZFS parameters are detected between the uncomplexed nitrene-functionalized ligand (in EtOH: D′ = 0.93 cm-1) and its sodium (NaBr@32 in EtOH: D′ = 0.88 cm-1) and potassium (KBr@32 in MTHF: D′ = 0.89 cm-1) complexes. If the photolysis of the free ligand is conducted at ambient temperature, a derivative of o-aminobenzaldehyde 4 is found to be the main product, which is formed by reaction of the o-iminoquinone methide 9 with water. The latter can be detected by UV/vis spectroscopy. Its lifetime is τ = 254 s in acetonitrile solution at ambient temperature. In the presence of diethylamine, the methyleneazepine derivative 5 is formed, which is indicative of didehydroazepine formation (7). Room-temperature photolysis of acetonitrile solutions of the sodium or potassium complexes also results in formation of the o-aminobenzaldehyde derivative. In the presence of diethylamine, however, no methyleneazepine 5 is found. Formation of the aniline derivative 8 instead points to free radical processes. Laser flash photolysis (LFP) of acetonitrile solutions of 1 leads to the detection of a short-lived (τ = 1.4 μs, λmax = 445 nm plus weak absorption at λ > 500 nm) intermediate A, which decays to transient B (τ = 8 ms, λ max = 295 and ca. 350-400 nm). LFP of acetonitrile solutions of complexes NaBr@1 and KBr@1 gives similar transient spectra. In the presence of sodium and potassium cations, the lifetime of the short-lived transient A is reduced (Na+: A′, τ = 200 ns K+: A″, τ = 160 ns). Transients A′ and A″ decay to long-lived transients B′ + C′ (B″ + C″). Based on the results of our product studies, a comparison with the low-temperature results, and quantum mechanical calculations, the transients A, A′, and A″ are identified as singlet nitrenes 12, NaBr@12, and KBr@12, while the long-lived transients B, B′, and B″ are assigned to didehydroazepines 7, NaBr@7, and KBr@7. Transients C′ and C″ can be assigned to aminyl radicals NaBr@16 and KBr@16. © 2005 American Chemical Society. 127 18 6883 6892 Cited By :12

We have investigated the role of transition metal impurities and oxygen vacancies in the formation of ferromagnetism in Co-doped TiO2 using the LSDA +U approach which takes into account strong on-site Coulomb correlations for electronic structure calculations. Several model supercells of rutile TiO2, with a Co2+ ion in high-spin state substituted into the titanium site and with oxygen vacancies, were considered. We found that the exchange interaction of Co magnetic ions is ferromagnetic, but very weak due to the large average impurity-impurity distance. However, it becomes three times stronger when there is a magnetic vacancy nearby. The magnetic moment values are 3 μB for Co2+ and -1 μB for vacancy. Our investigation showed that the exchange interaction energy of Co and vacancy moments varies from 330 to 40 meV depending on the distance between them in the supercell. We assume that the strong interaction between Co and vacancy moments should be taken into account to explain the high Curie temperature value in Co-doped TiO2. © 2006 IOP Publishing Ltd. The authors are very grateful to D Vollhardt for helpful discussions and to V V Mazurenko for the critical reading of the manuscript. This work was supported by the Russian Foundation for Basic Research under grants RFFI-04-02-16096 and RFFI-03-02-39024, by the joint UrO-SO Project N 25, the Netherlands Organization for Scientific Research through NWO 047.016.005, RFBR 05-02-16301 (IN), programs of the Presidium of the Russian Academy of Sciences (RAS) ‘Quantum macrophysics’ and of the Division of Physical Sciences of the RAS ‘Strongly correlated electrons in semiconductors, metals, superconductors and magnetic materials’. IAN acknowledges support from the Dynasty Foundation and the International Centre for Fundamental Physics in Moscow program for young scientists 2005, Russian Science Support Foundation program for young PhD of RAS 2005. AVL acknowledges support from the Dynasty Foundation and the International Centre for Fundamental Physics in Moscow.

The ability of different density functionals to describe the structural and energy differences between the high- [5T2g:(t2g)4(eg)2] and low- [1A1g:(t2g)6(eg)0] spin states of small octahedral ferrous compounds is studied. This work is an extension of our previous study of the hexaquoferrous cation, [Fe(H2O)6]2+, [J. Chem. Phys. 120, 9473 (2004)] to include a second compound—namely, the hexaminoferrous cation, [Fe(NH3)6]2+—and several additional functionals. In particular, the present study includes the highly parametrized generalized gradient approximations (GGAs) known as HCTH and the meta-GGA VSXC [which together we refer to as highly parametrized density functionals (HPDFs)], now readily available in the GAUSSIAN03 program, as well as the hybrid functional PBE0. Since there are very few experimental results for these molecules with which to compare, comparison is made with best estimates obtained from second-order perturbation theory-corrected complete active space self-consistent field (CASPT2) calculations, with spectroscopy oriented configuration interaction (SORCI) calculations, and with ligand field theory (LFT) estimations. While CASPT2 and SORCI are among the most reliable ab initio methods available for this type of problem, LFT embodies many decades of empirical experience. These three methods are found to give coherent results and provide best estimates of the adiabatic low-spin–high-spin energy difference, DeltaELHadia, of 12 000–13 000 cm–1 for [Fe(H2O)6]2+ and 9 000–11 000 cm–1 for [Fe(NH3)6]2+. All functionals beyond the purely local approximation produce reasonably good geometries, so long as adequate basis sets are used. In contrast, the energy splitting, DeltaELHadia, is much more sensitive to the choice of functional. The local density approximation severely over stabilizes the low-spin state with respect to the high-spin state. This "density functional theory (DFT) spin pairing-energy problem" persists, but is reduced, for traditional GGAs. In contrast the hybrid functional B3LYP underestimates DeltaELHadia by a few thousands of wave numbers. The RPBE GGA of Hammer, Hansen, and Nørskov gives good results for DeltaELHadia as do the HPDFs, especially the VSXC functional. Surprisingly the HCTH functionals actually over correct the DFT spin pairing-energy problem, destabilizing the low-spin state relative to the high-spin state. Best agreement is found for the hybrid functional PBE0.

An elevated plasma fibrinogen level is an independent risk factor for cardiovascular disease. Therefore, an understanding of the regulation of fibrinogen expression is important. Inflammation and genetic variation of the fibrinogen β gene regulate plasma fibrinogen levels, and there are indications that inflammation and genetic variation interact. The aim of our study was to gain more understanding of the regulation of the inflammatory response of the fibrinogen β gene and to determine the effects of genetic variation. Luciferase reporter gene assays in hepatoma cells, mutation analysis, and electrophoretic mobility shift assays were used to investigate the transcriptional regulation of the fibrinogen β promoter. We identified a hepatocyte nuclear factor-3 (HNF-3) site located just upstream of previously identified interleukin-6 (IL6)-responsive sequences. This HNF-3 site is essential for a full response of the promoter to IL6, which is a new function for HNF-3. The activity of the CCAAT box/enhancer-binding protein site (located 18 nucleotides downstream of the HNF-3 site and important to the IL6 response) depends on the integrity of the HNF-3 site and vice versa, explaining the necessity of HNF-3 in the IL6 response of the fibrinogen β promoter. Furthermore, small interfering RNA to HNF-3 reduces the fibrinogen β mRNA levels. The rare T allele of the -148C/T polymorphism, which is present between the binding sites of HNF-3 and CCAAT box/ enhancer-binding protein, interferes with this mechanism, and this polymorphism is in our assay system the only genetic determinant of IL6-induced promoter activity among six polymorphisms in the fibrinogen β promoter. © 2005 by The American Society for Biochemistry and Molecular Biology, Inc. Chemicals / CAS: fibrinogen, 9001-32-5; BBeta fibrinogen; DNA Primers; DNA-Binding Proteins; Fibrinogen, 9001-32-5; FOXA1 protein, human; FOXA2 protein, human; FOXA3 protein, human; Hepatocyte Nuclear Factor 3-alpha; Hepatocyte Nuclear Factor 3-beta, 135845-92-0; Hepatocyte Nuclear Factor 3-gamma, 135845-91-9; Interleukin-6; Luciferases, EC 1.13.12.-; Nuclear Proteins; RNA, Messenger; RNA, Small Interfering; Transcription Factors

We report results on the effect of the Al Ox barrier layer on the magnetic moment of Fe using polarized neutron reflection. The sample has nominal composition 25 nm Au5 nm Fe1.3 nm Al Ox GaAs (001). The metal deposition was done in ultrahigh vacuum and the Al oxidation was performed in two steps. From the fit to the neutron data we obtain for the magnetic moment of Fe the value (2.164±0.026) µB, very close to the bulk value (2.185 µB at room temperature). We conclude that there is no dead layer at the Al Ox interface. © 2005 American Institute of Physics. 97 10 Cited By :2

The environment, location and interaction of the Ce 3+ ions in the micropores of Al- and Zr-pillared clays have been studied by UV-vis-diffuse reflectance spectroscopy (UV-vis-DRS). The DRS spectra show that the chemical environment of the Ce 3+ ions in cerium exchanged clay is different from that of the Al- and Zr-pillared clays. The Al-Ce pillared clays (Al-Ce-PM) show four distinct absorption bands at 224, 263, 294 and 342 nm in the UV region which are attributed to 4f ? 5d interconfigurational transitions of Ce 3+ ions associated with alumina pillars. The O 2- ? Ce 3+ charge transfer band observed at 263 nm for Ce-exchanged and Al-Ce-PM clays is blue shifted by 10 nm for Ce-Zr-pillared clays (Ce-Zr-PM) due to fully hydrated Ce 3+ ions. The Ce 3+ ions are incorporated in the Al- and Zr-pillars possibly as AlCeO 3 and Ce xZr 1-xC 2 particles upon heat treatment. ? 2004 Elsevier B.V. All rights reserved.

An elevated plasma fibrinogen level is an independent risk factor for cardiovascular disease. Therefore, an understanding of the regulation of fibrinogen expression is important. Inflammation and genetic variation of the fibrinogen β gene regulate plasma fibrinogen levels, and there are indications that inflammation and genetic variation interact. The aim of our study was to gain more understanding of the regulation of the inflammatory response of the fibrinogen β gene and to determine the effects of genetic variation. Luciferase reporter gene assays in hepatoma cells, mutation analysis, and electrophoretic mobility shift assays were used to investigate the transcriptional regulation of the fibrinogen β promoter. We identified a hepatocyte nuclear factor-3 (HNF-3) site located just upstream of previously identified interleukin-6 (IL6)-responsive sequences. This HNF-3 site is essential for a full response of the promoter to IL6, which is a new function for HNF-3. The activity of the CCAAT box/enhancer-binding protein site (located 18 nucleotides downstream of the HNF-3 site and important to the IL6 response) depends on the integrity of the HNF-3 site and vice versa, explaining the necessity of HNF-3 in the IL6 response of the fibrinogen β promoter. Furthermore, small interfering RNA to HNF-3 reduces the fibrinogen β mRNA levels. The rare T allele of the -148C/T polymorphism, which is present between the binding sites of HNF-3 and CCAAT box/ enhancer-binding protein, interferes with this mechanism, and this polymorphism is in our assay system the only genetic determinant of IL6-induced promoter activity among six polymorphisms in the fibrinogen β promoter. © 2005 by The American Society for Biochemistry and Molecular Biology, Inc. Chemicals / CAS: fibrinogen, 9001-32-5; BBeta fibrinogen; DNA Primers; DNA-Binding Proteins; Fibrinogen, 9001-32-5; FOXA1 protein, human; FOXA2 protein, human; FOXA3 protein, human; Hepatocyte Nuclear Factor 3-alpha; Hepatocyte Nuclear Factor 3-beta, 135845-92-0; Hepatocyte Nuclear Factor 3-gamma, 135845-91-9; Interleukin-6; Luciferases, EC 1.13.12.-; Nuclear Proteins; RNA, Messenger; RNA, Small Interfering; Transcription Factors

The diffusion of hydrogen in sodium aluminum sodalite (NaAlSi-SOD) is modeled using classical molecular dynamics, allowing for full flexibility of the host framework, in the temperature range 800-1200 K. From these simulations, the self-diffusion coefficient is determined as a function of temperature and the hydrogen uptake at low equilibrium hydrogen concentration is estimated at 573 K. The influence of the cation distribution over the framework on the hydrogen self-diffusion is investigated by comparing results employing a low energy fully ordered cation distribution with those obtained using a less ordered distribution. The cation distribution is found to have a surprisingly large influence on the diffusion, which appears to be due to the difference in framework flexibility for different cation distributions, the occurrence of correlated hopping in case of the ordered distribution, and the different nature of the diffusion processes in both systems. Compared to our previously reported calculations on all silica sodalite (all-Si-SOD), the hydrogen diffusion coefficient of sodium aluminum sodalite is higher in the case of the ordered distribution and lower in case of the disordered distribution. The hydrogen uptake rates of all-Si-SOD and NaSiAl-SOD are comparable at high temperatures (approximately 1000 K) and lower for all-Si-SOD at lower temperatures (approximately 400 K).

The main goal of this study is to understand the mechanisms of adsorption of major cations occurring in groundwater on the Tournemire argillite. The Tournemire argillite contains illite, kaolinite, montmorillonite, quartz and calcite and some traces of pyrite. After calcite removal the mineralogical composition is kaolinite 47%, illite 26%, mixed-layer illite/montmorillonite 6%, montmorillonite 4%, chlorite 4% and quartz 13% with some traces of pyrite. The material was conditioned under homoionic form using Na, K, Cs, Ca and Mg. H was taken into account as a competitor ion for each case. For each cation-exchanged argillite, sorption edges were obtained as a function of pH. The "intrinsic" ion-exchange properties of this material, i.e. the concentrations of the different types of sites and the associated selectivity coefficients for H, Na, K, Cs, Ca and Mg were determined. The Tournemire argillite displays four kinds of sorption sites with respective concentrations of 0.04, 0.043, 0.046 and 0.078 mmol g-1. Besides, some sites in very low concentration (∼5×10-4 mmol g-1) have been revealed by performing adsorption isotherms of Cs. © 2004 Elsevier B.V. All rights reserved.

The objective of this research was to investigate the effect of cationization on inkjet printing quality. A cotton woven fabric was cationized by pretreatment with 2,3-epoxypropyl-trimethylammonium chloride (EPTAC) using a cold pad-batch method. For the prints, four reactive primary colors (CMYK) were used on both untreated and cationized cotton. The effects of thickener concentration, alkali concentration, and print resolution were investigated. Color yields, outline sharpness, colorimetric properties, fastness properties, staining of the white grounds, and penetration behavior were evaluated. It was found that inkjet printing with reactive dyes on cationized cotton has good potential for providing a cost effective and more environmentally friendly printing method using less dye, less thickener, and less alkali while maintaining high outline sharpness.

A threshold-photoelectron-coincidence spectrum of HBr has been recorded in the 32.2-35.8 eV photon energy range, with a resolution of approximately 0.01 eV, using a synchrotron radiation source. The X (3)Sigma(-) and a (1)Delta(2) states of the HBr(2+) dication are clearly observed in the spectrum, while there is no clear evidence for the formation of the b (1)Sigma(+) electronic state. For the first two states, the vibrational states v=0-3 have been resolved, while for the ground X (3)Sigma(-) state also spin-orbit splitting has been detected. The results appear in good agreement with previous experimental observations. A comparison with theoretical predictions indicates the role of "noncovalent" contributions to the interaction between the two atomic partners for the formation of metastable states.

We present measurements of electrical resistivity, thermal conductivity and thermopower of polycrystalline Sr-doped LaCoO3 with composition La0.95Sr0.05CoO3. Our data show that the investigated compound exhibits a very respectable room temperature thermoelectric figure of merit value of 0.18. Our results not only show that oxides are promising candidates for thermoelectric cooling applications, but also point towards the need for careful theoretical calculations that will serve as a guide in producing the next generation of thermoelectric materials., 13 pages, 3 figures, Accepted in Appl. Phys. Lett. scheduled to appear on Feb 17, 2004 issue

We have used scanning SQUID magnetometry to image vortices in ultrathin (Ba(0.9)Nd(0.1)CuO(2+x))(m)/(CaCuO(2))(n) high temperature superconductor samples, with as few as three superconducting CuO(2) planes. The Pearl lengths (Lambda=2lambda(L)(2)/d, lambda(L) the London penetration depth, d the superconducting film thickness) in these samples, as determined by fits to the vortex images, agree with those by local susceptibility measurements, and can be as long as 1 mm. The in-plane penetration depths lambda(ab) inferred from the Pearl lengths are longer than many bulk cuprates with comparable critical temperatures. We speculate on the causes of the long penetration depths, and on the possibility of exploiting the unique properties of these superconductors for basic experiments.

Changes in agricultural practices are expected to affect groundwater quality by changing the loads of nutrients and salts in recharging groundwater, but regional monitoring networks installed to register the changes often fail to detect them and interpretation of trend analysis results is difficult. This study aims to improve the detection and understanding of groundwater quality changes with time, combining time series information, concentration-depth profiles, age dating and concentration-depth prognoses based on the historical inputs of solutes. For trend detection, a combination of trend analysis on time series at specific depths and time-averaged concentration-depth profiles was used. To reveal trends that have become obscured by chemical reactions, additional conditionally conservative indicators were introduced that are insensitive to those reactions under specific conditions. Detected trends were matched with prognoses of conservative and reactive transport to aid the understanding of trends. Data of the regional networks in 2 area-types with intensive livestock farming in the Dutch province of Noord-Brabant were used to illustrate the approach. The downward movement of the agricultural pollution front was demonstrated for the 2 area-types. However, many targeted contaminants have become retarded or delayed and quality changes were hard to detect for many reactive solutes, including nitrate. Pollution fronts of these targeted chemical components are still limited to the first 15 m of the subsoil. At deeper level, about 20-25 m, the effects of agricultural pollution and acidification were indicated by chemical indicators that have not been considered by others: oxidation capacity, the sum of cations and chloride. Increasing trends of the conditionally conservative indicators 'oxidation capacity' and 'sum of cations' were found at a depth of 18-25 m below surface. Increasing trends for potassium were found at shallower depth (7-13 m), which is explained by retardation of potassium due to cation-exchange with calcium and magnesium. The modelled cation-exchange explained the shape of the concentration-depth profile and the increasing trends at shallow depth in the aquifer. © 2004 Elsevier B.V. All rights reserved.

A product and time-resolved kinetic study of the one-electron oxidation of ring-dimethoxylated phenylethanoic acids has been carried out at different pH values. Oxidation leads to the formation of aromatic radical cations or radical zwitterions depending on pH, and pK(a) values for the corresponding acid-base equilibria have been measured. The radical cations undergo decarboxylation with first-order rate constants (k(dec)) ranging from

In this study, the adsorption behavior of natural (clinoptilolite) zeolites with respect to Co2+, Cu2+, Zn2+, and Mn2+ has been studied in order to consider its application to purity metal finishing wastewaters. The batch method has been employed, using metal concentrations in solution ranging from 100 to 400 mg/l. The percentage adsorption and distribution coefficients (K-d) were determined for the adsorption system as a function of sorbate concentration. In the ion exchange evaluation part of the study, it is determined that in every concentration range, adsorption ratios of clinoptilolite metal cations match to Langmuir, Freundlich, and Dubinin-Kaganer-Radushkevich (DKR) adsorption isotherm data, adding to that every cation exchange capacity metals has been calculated. It was found that the adsorption phenomena depend on charge density and hydrated ion diameter. According to the equilibrium studies, the selectivity sequence can be given as Co2+ > Cu2+ > Zn2+ > Mn2+. These results show that natural zeolites hold great potential to remove cationic heavy metal species from industrial wastewater. (C) 2004 Elsevier Inc. All rights reserved. C1 Pamukkale Univ, Dept Chem, Fac Sci & Arts, TR-20017 Denizli, Turkey. Pamukkale Univ, Dept Chem Engn, Fac Engn, TR-20017 Denizli, Turkey.

The title compound (C13H30N2O 7S) has been determined from three-dimensional X-ray diffraction data. The crystals are monoclinic, a = 22.654(8) �, b = 8.652(4) �, c = 23.925(9) �, ?= 123.880(9)�, V= 3893(3) �3, Z = 8, Dcalc =1.192 g/cm3, space group C2/c. The structure was solved by direct methods and refined by full-matrix least squares method (R = 0.051). The ammonium cation is displaced by 1.08 � from the mean plane of the ligand causing hydrogen bonding with the macrocyclic O atoms in a perching arrangement. The thiocyanate anion forms an extended hydrogen bonded chain with the cation via the occluded water molecule. ? 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In this article, calix[4]arene ketone derivative was used as a carrier to transport Hg 2+ ions from an aqueous solution into an aqueous receiving solution. The kinetic parameters (k 1 , k 2 , R m max , t max , J d max , J a max ) were investigated with influence of temperature, the solvent, and stirring rate and analyzed in the formation of two consecutive, irreversible first order reactions. The membrane entrance rate, k 1 , and the membrane exit rate, k 2 , constants were increased with temperature and stirring rate and found to be dependent on the solvent type in the order CH 2 Cl 2 > CHCl 3 > CCl 4 . The activation energy was obtained as 5.28 kcal/mol from the slope of the Arrhenius plot for the case of maximum membrane exit flux, J a max . This value indicates that the process is controlled by species diffusion.

Changes in agricultural practices are expected to affect groundwater quality by changing the loads of nutrients and salts in recharging groundwater, but regional monitoring networks installed to register the changes often fail to detect them and interpretation of trend analysis results is difficult. This study aims to improve the detection and understanding of groundwater quality changes with time, combining time series information, concentration-depth profiles, age dating and concentration-depth prognoses based on the historical inputs of solutes. For trend detection, a combination of trend analysis on time series at specific depths and time-averaged concentration-depth profiles was used. To reveal trends that have become obscured by chemical reactions, additional conditionally conservative indicators were introduced that are insensitive to those reactions under specific conditions. Detected trends were matched with prognoses of conservative and reactive transport to aid the understanding of trends. Data of the regional networks in 2 area-types with intensive livestock farming in the Dutch province of Noord-Brabant were used to illustrate the approach. The downward movement of the agricultural pollution front was demonstrated for the 2 area-types. However, many targeted contaminants have become retarded or delayed and quality changes were hard to detect for many reactive solutes, including nitrate. Pollution fronts of these targeted chemical components are still limited to the first 15 m of the subsoil. At deeper level, about 20-25 m, the effects of agricultural pollution and acidification were indicated by chemical indicators that have not been considered by others: oxidation capacity, the sum of cations and chloride. Increasing trends of the conditionally conservative indicators 'oxidation capacity' and 'sum of cations' were found at a depth of 18-25 m below surface. Increasing trends for potassium were found at shallower depth (7-13 m), which is explained by retardation of potassium due to cation-exchange with calcium and magnesium. The modelled cation-exchange explained the shape of the concentration-depth profile and the increasing trends at shallow depth in the aquifer. © 2004 Elsevier B.V. All rights reserved.

Reconstructive transformations in layered silicates need a high tem- perature in order to be observed. However, very recently, some systems have been found where transformation can be studied at temperatures 600 C below the lowest experimental results previously reported, including sol-gel methods. We explore the possible relation with the existence of intrinsic localized modes, known as discrete breathers. We construct a model for nonlinear vibrations within the cation layer, obtain their parameters and calculate them numerically, obtaining their energies. Their statistics shows that although there are far less breathers than phonons, there are much more above the activation energy, being therefore a good candidate to explain the reconstructive transformations at low temperature., Comment: 27 pages, 11 figures

Gadolinia-doped ceria electrolyte Ce 0.8 Gd 0.2 O 2− δ (CGO) and perovskite-type mixed conductor La 0.8 Sr 0.2 Fe 0.8 Co 0.2 O 3− δ (LSFC), having compatible thermal expansion coefficients (TECs), were combined in dual-phase ceramic membranes for oxygen separation. Oxygen permeability of both LSFC and composite LSFC/CGO membranes at 970–1220 K was found to be limited by the bulk ambipolar conductivity. LSFC exhibits a relatively low ionic conductivity and high activation energy for ionic transport (∼200 kJ/mol) in comparison with doped ceria. As a result, oxygen permeation through LSFC/CGO composite membranes, containing similar volume fractions of the phases, is determined by the ionic transport in CGO. The permeation fluxes through LSFC/CGO and La 0.7 Sr 0.3 MnO 3− δ /Ce 0.8 Gd 0.2 O 2− δ (LSM/CGO) composites have comparable values. An increase in the p-type electronic conductivity of ceria in oxidizing conditions, which can be achieved by co-doping with variable-valence metal cations, such as Pr, leads to a greater permeability. The oxygen ionic conductivity of the composites consisting of CGO and perovskite oxides depends strongly of processing conditions, decreasing with interdiffusion of the phase components, particularly lanthanum and strontium cations from the perovskite into the CGO phase.

Three new, isostructural methylenediphosphonates of molybdenum, A[MoO2(O3PCH2PO3H)] (A = Rb (1), NH4 (2) and Tl (3)) have been synthesized by hydrothermal method and structurally characterised by X-ray diffraction and spectroscopic techniques. These compounds crystallize in monoclinic space group, P21/c with Z = 4 and consist of [MoO2(O3PCH2PO3H)]- anionic layers interleaved with A+ ions.

Activated carbons were developed from Casurina equisetifolia leaves, by chemically treating with sulfuric acid (1:1) or zinc chloride (25%), at low (425 �C) and high (825 �C) temperatures. The resulting powdered activated carbons were applied for removing mercuric ions from aqueous solution at different agitation times and mercuric ion concentrations. The equilibrium data fitted well the Langmuir adsorption isotherm. The Langmuir adsorption capacities were 12.3 and 20.3 mgg-1 for low temperature carbons and 43.9 and 38.5 mgg-1 for high temperature carbons impregnated with H2SO4 and ZnCl2, respectively. Studies of the effects of carbon dosage, NaCl concentrations and solution pH values were carried out for the more effective, high temperature carbons. Increasing NaCl concentration resulted in a significant decrease in the adsorption efficiency. Adsorption was high from solutions with low and neutral pH values and lower for solutions with alkaline pH values for the high temperature carbons. ? 2003 Elsevier Science Ltd. All rights reserved.

The absolute photoionization cross sections of doubly ionized silicon in the ground state as a function of photon energy in the region of 2p threshold (95eV-170eV) was presented. The cross sectional values contained a small contribution from metastable Si2+ that did not exceed 3%. The relativistic random-phase approximation (RRPA) was used to calculate the 2p photoionization continuum cross sections and agreed well with the corresponding measurements. It was found that the satellite transitions play an important role in the photoionization of Si2+.