bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of the Tropospheric Concentration of OH with Model Calculations
Authors: Poppe D. , Wallasch M. , Zimmermann J. , Doru H. P. , Ehhalt D. H.
Published: May 2011

The influence of chemical precursors and sunlight on the atmospheric OH abundance is investigated by a comparison of measured tropospheric OH with model calculations. The latter are based on the gas phase reaction mechanism of the Regional Acid Deposition Model (RADM2) which incorporates an explicit inorganic and a comprehensive organic chemistry. For rural environments in Deuselbach and Schauinsland with a low burden of hydrocarbons and nitrogen oxides the calculated and measured OH‐concentrations correlate well. The model overpredicts OH by about 10%. Under more polluted conditions in Jülich the correlation coefficient between experimental and modeled data are significantly smaller. On the average the model overpredicts OH concentrations by a factor of 1.8. Possible reasons are the influence of not measured precursors, for example isoprene, and the inapplicability of a quasi steady state model under the spatially inhomogeneous conditions in Jülich.
The Production and Release to Atmosphere of Industrial Halocarbons
Authors: Midgley Pauline
Published: May 2011

The available surveys of production and use carried out by the halocarbon industry for a number of important chlorine and bromine containing chemicals are summarised. The results of a new survey in which methyl chloroform production data were reconfigured into more detailed geographical regions for comparison with atmospheric measurements are presented.
Ground Based Measurements of Atmospheric Gases by Spectroscopic Methods
Authors: Schiff H. I.
Published: May 2011

Spectroscopic methods afford a number of advantages for making atmospheric measurements. It is a passive technique which is capable of making real time, in situ measurements. Since each molecules has a characteristic spectrum it is possible to make simultaneous measurement of a number of species. In addition, unequivocal identification of the target species is possible if the instrument has sufficient spectral resolution. Detection limits as low as 1 part in 1013 have been reported as well as dynamic ranges as high as 108. Temporal resolution of fractions of a second can be achieved for “eddy correlation” flux measurements. – Fourier Transform Infrared Spectroscopy (FTIR) is, perhaps, the most universal method and is particularly useful in identifying new species in heavily polluted air. However, it lacks the sensitivity required for measurements of trace gases in clean air. Differential Optical Absorption Spectroscopy (DOAS) operates in the visible and the near UV which limits the number of measurable species. But it is capable of measuring highly reactive gases such as OH, NO3, and HONO. Tunable Diode Laser Absorption Spectroscopy (TDLAS) has very high spectral resolution, sensitivity and time response. Its main disadvantage is the need for a number of laser diodes to cover a wide spectral range. Laser Induced Fluorescence (LIF) is also capable of both high sensitivity and specificity. However, rather complex excitation sources have to be devised for each gas being investigated. Photoacoustic Absorption Spectroscopy (PAS) is, in principle very simple and capable of simultaneous measurements. In practice, however, it suffers from lack of resolution and serious interferences from CO2 and H2O.
Photoacoustic Air Pollution Monitoring with an Isotopic CO2 Laser
Authors: Trushin S. A.
Published: May 2011

This paper considers the possibilities of using lasers based on rare isotopic species of carbon dioxide to detect trace quantities of pollutants in ambient air by photoacoustic spectroscopy (PA). The use of isotopic CO2‐laser lines allows to overcome the background absorption of atmospheric carbon dioxide. The effect of water vapor continuum absorption is eliminated by decreasing the gas pressure in the PA cell. The spectroscopic analysis performed within the framework of GEISA‐84. Database shows that even at a 10%‐measurement error detection sensitivities of 0.1–10 ppbV for NH3, C2H4, O3, HNO3, PH3 and ClO in ambient air can be achieved. A simple PA gas analyzer on the basis of a 13C16O2‐laser with a NH3 sensitivity of ≠1 ppbV and a time resolution of 1.5 min is also described.
Maximum Supercooling of H2SO4Acid Aerosol Droplets
Authors: Luo B. P. , Peter Th. , Crutzen P. J.
Published: May 2011

Heterogeneous reactions which take place on solid polar stratospheric cloud (PSC) particles and lead to ClOxactivation, have been identified as crucial to polar ozone destruction. Scientific attention is currently focussed on whether similar heterogeneous reactions can also take place on sulfuric acid aerosol droplets. We present theoretical calculations of the homogeneous freezing of sulfuric acid droplets under stratospheric conditions, based on classical theory and using the best available thermodynamical data for the H2SO4–H2O system. For small cooling rates we find that most of the aerosol droplets will freeze as sulfuric acid tetrahydrate (SAT) at about 200 K, whereas for large cooling rates (e. g. in lee waves) large amounts of the aerosol droplets will stay liquid through temperatures as low as 190 K, at which point they freeze as water ice.
Stratospheric Aerosol Increases and Ozone Destruction: Implications from Mass Spectrometer Measurements
Authors: Arnold Frank
Published: May 2011

Stratospheric aerosol increases set the stage for increased halogen‐catalyzed ozone destruction. Most striking examples are polar stratospheric aerosols, so called polar stratospheric clouds (PSC's) and volcanic eruption clouds. Balloon‐ and rocket‐borne mass spectrometer measurements made by our reserach group have offered interesting new insights into these aerosol clouds. The present paper investigates, in the light of these measurements, the formation and role of the most common type of PSC's and volcanic eruption clouds. It is concluded that PSC's are mostly formed by nitric acid nucleation and/or ‐condensation leading to metastable HNO3/H2O‐condensates. In contrast, it seems that NAT (nitric acid trihydrate being the most stable HNO3/H2O‐condensate) does not form easily. The metastable condensates may be supercooled solution droplets or solid solutions, having lower existence temperatures than NAT. Volcanic H2SO4/H2O‐aerosols are formed by injection of sulfur‐bearing gases, mostly SO2, followed by photochemical conversion to gaseous H2SO4, which undergoes rapid condensation on preexisting H2SO4/H2O‐aerosols. The mass spectrometer measurements suggest that these H2SO4/H2O‐aerosols have an important role in setting the stage for halogen‐catalyzed ozone‐destruction.
LIDAR Measurements of Stratospheric Aerosols in the Arctic
Authors: Neuber R. , Beyerle G. , Schrems O.
Published: May 2011

A LIDAR instrument is operated at Ny‐Ålesund, Spitsbergen (79N, 12E). Backscatter profiles of stratospheric aerosols like polar stratospheric clouds (PSCs) are determined at a wavelength of 353 nm. PSC data are shown for January 1989 and 1990. The data are correlated with atmospheric temperature. In August 1991 an aerosol layer was found, which presumably originates from the volcanic eruption of Mount Pinatubo. The modification of the LIDAR instrument for the European Arctic Stratospheric Ozone Expedition (EASOE) in the winter 1991/92 is presented.
A Micro‐Physical Box Model for EASOE: Preliminary Results for the January/February 1990 PSC Event over Kiruna
Authors: Peter Th. , Müller R. , Drdla K. , Petzoldt K. , Reimer E.
Published: May 2011

First results of a trajectory box model designed for the European Arctic Stratospheric Ozone Experiment (EASOE) are presented. The model contains a comprehensive description of both types of polar stratospheric particles, NAT on aerosol (Type‐I) and ice on NAT (Type‐II), including nucleation, growth/evaporation, and sedimentation of particles. The performance of the model is tested for the case of the polar stratospheric cloud (PSC) event January 31–February 1, 1990 over Kiruna (north Sweden). Comparison of the model results with measurements from two stratospheric balloon flights shows that the theory can reproduce the data provided the following two conditions are satisfied: (a) a strong lee wave activity was present at the time of the ballon flights; (b) the nucleation of NAT on H2SO4 is either governed by a high barrier energy or delayed due to insufficient freezing of the background aerosol. These results indicate an urgent need for both, the implementation of lee wave effects into the existing trajectory models and a better understanding of the NAT nucleation on the background aerosol.
Photoreactivity of Molecular Aggregates
Authors: Vaida Veronica , Jefferson Anne , Rühl Eckart
Published: May 2011

The spectroscopy and photoreactivity of atmospheric trace gases embedded in clusters is examined in this work. Perturbations induced by intermolecular interactions are obtained in order to evaluate the role that the heterogeneous photochemistry of such species could play in the chemical balance of the atmosphere. – Spectroscopic effects are monitored using aggregates produced in supersonic jets and measured by high resolution Fourier Transform direct ultraviolet absorption techniques. These spectra are compared with those of the isolated molecule to extract shifts and intensity changes when the chromophore is clustered. Photochemical studies involve laser pump‐probe experiments with mass resolved multiphoton ionization detection. Changes in the isolated molecule photochemistry are monitored as a function of cluster formation. – This paper discusses the methodology developed as well as the specific example of clusters of ozone with atmospheric trace gases.
Photolysis of Ketene‐Oxygen Mixtures between 253 K and 323 K in Relation to the Formation of Criegee Intermediates
Authors: Horie O. , Moortgat G. K.
Published: May 2011

Ketene was photolyzed in a flow reactor in Ar/O2 = 80/20 carrier gas between 253 and 323 K. Products observed by matrix‐isolation FTIR spectroscopy were CO, CO2, O3, HCHO, HCOOH, and CH3C(O)OC(O)H, formic‐acetic anhydride. Addition of HCHO did not produce hydroxymethyl formate, CH2(OH)OCHO, a product expected from the reaction of the stabilized Criegee intermediate H2COO with HCHO. Photolysis in the presence of a large excess of water vapour did not change the product pattern. It was concluded that no stabilized Criegee intermediates were formed under the experimental conditions.
FTIR Studies on the Photooxidation Mechanisms of CH3Cl, CH3Br, CHBr3 and CF3Br
Authors: Weller R. , Lorenzen‐Schmidt H. , Schrems O.
Published: May 2011

The Photooxidations of CH3Cl, CH3Br, CF3Br, and CHBr3 in dry‐air have been investigated at 298 K in a static reaction vessel by means of FTIR spectroscopy. Irradiation of the reaction mixtures has been performed by Hg‐resonance lamps (184.9 nm and 253.7 nm lines) and broad band UV‐fluorescence lamps (300–400 nm). The photooxidation mechanism of CH3Cl and CH3Br is governed by two different pathways: 1) photolytical release of halogen atoms and subsequent oxidation of the CH3 radical, 2) abstraction of an H‐atom and oxidation of the respective CH2Cl and CH2Br‐fragment. The second path leads to the formation of the formyl‐halides HClCO and HBrCO which are transferred to CO and HCl or CO and HBr, respectively. Addition of trace amounts of NO to the gas mixture decreases the HClCO yield strongly. We suggest that NO reacts with the transient H2ClCO‐radical to ClNO + H2CO. HBrCO, Br2CO and the final products CO, CO2, and HBr could be identified after Hg‐resonance lamps induced photooxidation of CHBr3. The Cl2/fluorescence lamps induced photooxidation, however, yielded solely Br2CO, CO2, and HBr. In contrast to the labile species HClCO, HBrCO, and Br2CO, the photooxidation product of CF3Br, carbonyl fluoride (F2CO) is relatively inert under our reaction conditions.
A Novel Laser‐Based Technique for the Time‐Resolved Study of Integrated Hydrocarbon Oxidation Mechanisms
Authors: Hoffmann A. , Mörs V. , Zellner R.
Published: May 2011

An experimental method has been developed to study the formation of OH radicals and of NO2 in the integrated oxidation chain of hydrocarbons under NOx‐rich tropospheric conditions. In this technique the oxidation of hydrocarbons is initiated by laser pulse photolysis of Cl2 and the temporal behaviour of OH and NO2 is monitored by direct time‐resolved cw‐laser absorption and LIF, respectively. Combined with computer modelling of the complete oxidation mechanisms the results allow the determination of (i) the extent of NO/NO2 conversion and hence the ozone formation potential of individual hydrocarbons and (ii) the branching ratio of HO2 formation relative to other reaction channels of alkoxy radicals. First applications of this technique to the oxidation of C2H6 and C3H8 are presented.
Electron Attachment Processes in Molecular Aggregates
Authors: Hashemi Reza , Meinke Martina , Jaffke Thomas , Illenberger Eugen
Published: May 2011

Reactions in negatively charged clusters following resonant electron attachment have been studied in a supersonic beam experiment. The results are discussed with respect to the correspondent processes from single molecules in the gas phase and from condensed molecules. It is shown that electron capture by oxygen clusters allows the population of electronic states in O2− not accessible in the single‐electron‐molecule frame of reference (violation of the σ− selection rule). Clusters composed of O2/CF2Cl2 yield ionic products composed of both constituents. They are generated along a complex scattering process within the ionized aggregate. The resonance profiles of their ion yields contain information on their genesis, i.e. the initial step of electron capture by the electrophore in the cluster. Since these reactions occur predominantly at low energies, sometimes at zero eV, we consider them as highly relevant in any environment (gaseous or condensed) where low energy electrons are present.
Metal Ion Catalyzed Autoxidation of Sulfur(IV)‐Oxides: Redox Cycling of Metal Ions Induced by Sulfite
Authors: van Eldik R. , Coichev N. , Bal Reddy K. , Gerhard A.
Published: May 2011

The important role of metal ion catalyzed autoxidation reactions of sulfur(IV)‐oxides in aqueous solution has been confirmed by numerous investigations. In general, transition metals such as Co, Fe and Mn in the 3+ oxidation state can rapidly oxidize HSO3−/SO32‐ to produce the reduced metal ions in the 2 + oxidation state and the SO3− radical, which can subsequently initiate a series of free radical propagation reactions. Experimental results are reported to demonstrate how low concentration levels of sulfite can effectively induce the autoxidation of the reduced metal ions in order to complete the catalytic cycle. In this way the mentioned metal ions exhibit redox cycling in which the nature of the redox process is determined by the sulfite and oxygen concentration levels in solution. A general mechanism to account for these observations, as well as for the synergistic effect usually observed for such reactions, is presented.
Kinetics and Mechanism of Sulfur(IV) Oxidation by Hydrogen Peroxide in Aqueous Phase: The Non‐Linear Parts of the pH‐Profile
Authors: Drexler C. , Elias H. , Fecher B. , Wannowius K. J.
Published: May 2011

Stopped‐flow spectrophotometry was used to study the oxidation of S(IV) by H2O2 at 285 K and 298 K, respectively, in the pH range −0.3 to 13 in buffered aqueous solution under pseudo‐first‐order conditions (I = 0.5, 1.0 and 2.0 M NaClO4, respectively). The reaction of HSO3− with H2O2 is subject to general‐acid catalysis whereas that of the SO32‐ ion is not. The dependence of the experimental first‐order rate constant on the concentration of the excess partner [H2O2] was studied in detail. — In the pH range −0.3 to 6 the rate is given by Eq. (1) (KR1 and KS1: acid dissociation constants of H3O2+ and SO2, respectively; [H] = proton activity).

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Kexp is the experimental overall equilibrium constant for the various protonation steps involved in the formation of the intermediate peroxosulfurous acid (= PSA), whereas K is the equilibrium constant for the formation of PSA. Its decay (k = 740 s−1 at 285 K) controls the rate of S(V1) formation. The pKa of the species H3O2+ as derived from the kinetic data, is found to be pKR1 = 1.5–2.0. —In the pH range 6–8, the rate is given by pKa(HSO3−)).

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At pH > 8, the rate is governed by Eq. (3) pKa(HSO3−

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The data for k, K, kH, kHOH, k and k are presented and the mechanistic implications of rate laws (1)–(3) are discussed.
Vertical Transport of Trace Species by Thunderstorms — A Transilient Transport Model
Authors: Alheit R. R. , Hauf T.
Published: May 2011

A 2D‐cloud model with spectral microphysics including ice physics and aerosol particle scavenging effects is used to simulate the 19 July 1981 CCOPE thunderstorm case. The net vertical transport of a chemically inert tracer between 30 respective levels by a single thunderstorm was determined in terms of a transilient matrix. Additionally, the redistribution of sulfur which was assumed to be initially present in aerosol particles was investigated. Beside transport with the mean wind, nucleation scavenging, particle scavenging, and wet deposition contribute to the observed redistribution. — The simulations show that even a moderate thunderstorm may reduce the pollution in the boundary layer by 50%. Trace species may be transported in less than half an hour from the ground to the upper troposphere and, in contrast, trace species originating from the upper troposphere may not have the change to be transported down to the ground. Net mixing strongly depends on the detailed dynamical and microphysical structure of the investigated thunderstorm. The hypothesis that thunderstorms play an important role in redistribution and wet deposition of airborne aerosol particle mass is confirmed.
Meta-analysis of two randomized controlled trials to identify long-term symptoms after division of the short gastric vessels during Nissen fundoplication
Authors: Engström C , Jamieson G G , Devitt P G , Watson D I
Published: May 2011

Background

Randomized trials suggest that division of the short gastric vessels during Nissen fundoplication is unnecessary. Some trials report an increased risk of gas bloat symptoms following division of the short gastric vessels. In this study long-term follow-up data from the two largest randomized clinical trials of division versus no division of the short gastric vessels during laparoscopic Nissen fundoplication were combined to determine whether there were differences in late outcome.

Methods

Patients with gastro-oesophageal reflux disease who underwent primary laparoscopic antireflux surgery and were included in two previously reported randomized trials were studied. Of 99 patients enrolled in the Swedish study and 102 in the Australian study, the short gastric vessels were divided in 104 and left intact in 97. Data sets were combined and late clinical outcomes analysed.

Results

At 10–12 years' follow-up (mean 11·5 years) clinical data were obtained from 170 patients (86 with vessels divided, 84 undivided). Statistical analysis of the combined data set showed no significant differences in symptoms of heartburn or dysphagia, ability to belch or vomit, and use of antisecretory medications. Division of the short gastric vessels was associated with a higher rate of bloating symptoms (72 versus 48 per cent; P = 0·002).

Conclusion

Division of the short gastric vessels is followed by a slightly poorer clinical outcome at late follow-up after Nissen fundoplication. Surgeons should avoid dividing these vessels when undertaking a laparoscopic Nissen fundoplication.
Analysis of aggregate size as a process variable affecting paclitaxel accumulation in Taxus suspension cultures
Authors: Kolewe Martin E. , Henson Michael A. , Roberts Susan C.
Published: May 2011

Plant cell aggregates have long been implicated in affecting cellular metabolism in suspension culture, yet the rigorous characterization of aggregate size as a process variable and its effect on bioprocess performance has not been demonstrated. Aggregate fractionation and analysis of biomass‐associated product is commonly used to assess the effect of aggregation, but we establish that this method is flawed under certain conditions and does not necessarily agree with comprehensive studies of total culture performance. Leveraging recent advances to routinely measure aggregate size distributions, we developed a simple method to manipulate aggregate size and evaluate its effect on the culture as a whole, and found that Taxus suspension cultures with smaller aggregates produced significantly more paclitaxel than cultures with larger aggregates in two cell lines over a range of aggregate sizes, and where biomass accumulation was equivalent before elicitation with methyl jasmonate. Taxus cuspidata (T. cuspidata) P93AF cultures with mean aggregate sizes of 690 and 1,100 μm produced 22 and 11 mg/L paclitaxel, respectively, a twofold increase for smaller aggregates, and T. cuspidata P991 cultures with mean aggregate sizes of 400 and 840 μm produced 6 and 0.3 mg/L paclitaxel, respectively, an increase of 20‐fold for smaller aggregates. These results demonstrate the importance of validating experiments aimed at a specific phenomenon with total process studies, and provide a basis for treating aggregate size as a targeted process variable for rational control strategies. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Quantitative Contrast Evaluation of an Industry‐Style Rhodium Nanocatalyst with Single Atom Sensitivity
Authors: Specht Petra , Gulotty Robert J. , Barton David , Cieslinski Robert , Rozeveld Steve , Kang Joo H. , Dubon Oscar. D. , Kisielowski Christian
Published: May 2011

Aberration‐corrected electron microscopy opens new ways for material characterization. In catalyst research it will enable the observation of single atom arrangements, such as the location of promoter atoms on catalyst particles. However, quantitative procedures must be developed to account for dynamic contrast changes resulting from beam‐sample interactions and incoherent instrument aberrations. We demonstrate that at low acceleration voltage (80 kV), for which knock‐on damage is suppressed, the residual intensity fluctuations can be attributed to the presence of phonons resulting in 3D low frequency atom displacements. For rhodium [110] oriented particles it was found that the catalysts are platelets with an aspect ratio of about 0.2 and a surface roughness of ±1 atom. Observation of single surface atoms requires minimization of phonon‐induced motion.
Dealloying Ag–Al Alloy to Prepare Nanoporous Silver as a Substrate for Surface‐Enhanced Raman Scattering: Effects of Structural Evolution and Surface Modification
Authors: Qiu Huajun , Zhang Zhonghua , Huang Xirong , Qu Yinbo
Published: May 2011

Sensitive detection of molecules by using the surface‐enhanced Raman scattering (SERS) technique depends on the nanostructured metallic substrate and many efforts have been devoted to the preparation of SERS substrates with high sensitivity, stability, and reproducibility. Herein, we report on the fabrication of stable monolithic nanoporous silver (NPS) by chemical dealloying of Ag–Al precursor alloys with an emphasis on the effect of structural evolution on SERS signals. It was found that the dealloying conditions had great influence on the morphology (the ligament/pore size) and the crystallization status, which determined the SERS signal of rhodamine 6G on the NPS. NPS with small pores, low residual Al, and perfect crystallization gave high SERS signals. A high enhancement factor of 7.5×105 was observed on bare NPS obtained by dealloying Ag30Al70 in 2.5 wt % HCl at room temperature followed by 15 min aging at around 85 °C. After coating Ag nanoparticles on the NPS surface, the enhancement factor increased to 1.6×108 owing to strong near‐field coupling between the ligaments and nanoparticles.
Remarkable Differences in the Coordination Chemistry of Structurally Related 1,2,4‐Triphosphaferrocenes with Copper(I) Halides and Silver(I) Salts
Authors: Deng Shining , Schwarzmaier Christoph , Zabel Manfred , Nixon John F. , Bodensteiner Michael , Peresypkina Eugenia V. , Balázs Gábor , Scheer Manfred
Published: May 2011

The coordination behavior of 1,2,4‐triphosphaferrocenes [FeCpR(η5‐P3C2tBu2)] [CpR = Cp (1), Cp″′ = η5‐C5H2tBu3 (3)] towards CuI halides is significantly influenced by the substitution pattern of the cyclopentadienyl ring attached to the iron atom. The reaction of the Cp derivative 1 with CuBr in a 1:1 stoichiometry leads to the dimeric complex [{FeCp(η5:η1:η1‐P3C2tBu2)}{μ‐CuBr(MeCN)}]2 (5b), in which two 1,2,4‐triphosphaferrocenes are linked by two CuBr units. By using a 1:2 stoichiometry, the 1D polymeric compound [{FeCp(η5:η1:η1:η1‐P3C2tBu2)}μ‐{(CuBr)3(MeCN)2}]n (6) is formed in which the triphosphaferrocenes are bridged by (CuBr)2{CuBr(MeCN)2} units. Starting from CuI, independent of the stoichiometry, the cage compound [{FeCp(η5:η1:η1‐P3C2tBu2)}3{Cu(μ‐I)}3{Cu(μ3‐I)}3{Cu(NCMe)}(μ6‐I)](7) is formed. However, if the bulky Cp″′ derivative 3 is used already in a 1:1 stoichiometry with CuBr, a transformation of the initially five‐membered 1,2,4‐triphospholyl ring into a four‐membered 1,2‐diphosphete ligand is observed, which is linked by CuBr moieties forming the dimeric paramagnetic complex [{FeCp″′(η4:η1:η1‐P2C2tBu2)}(μ‐CuBr)]2 (9). Furthermore, applying a 1:2 stoichiometry between 3 and CuX (X = Br, I) the complete fragmentation of the 1,2,4‐triphospholyl ring under mild conditions into a tetraphosphabutadiene ligand is observed. In the formed 1D polymeric complexes [{(FeCp″′)2(μ,η4:η1:η1‐P4)}{(μ‐CuX)2(MeCN)}]n [X = Br (10a), I (10b)] this ligand represents now the middle deck of the triple‐decker sandwich complexes linked by four‐membered [(CuX)2(CH3CN)] moieties. Moreover, the reaction of the Cp derivative 1 with the Ag salt of the weakly coordinating anion [Al{OC(CF3)3}]4– leads to the dimeric Ag(CH3CN)‐bridged dicationic product [{FeCp(η5‐P3C2tBu2)}Ag(MeCN)]2[Al{OC(CF3)3}4]2 (11).
Preparation of Nitrogen‐Substituted Ferrocene Derivatives by Aza‐Wittig Methodologies
Authors: Molina Pedro , Tárraga Alberto , Alfonso María
Published: May 2011

Several methodologies based on the aza‐Wittig reaction, mainly developed by our research group, have been used for the preparation of a wide variety of ferrocenes containing nitrogen functionalities. Syntheses of mononuclear and nitrogen‐rich multinuclear ferrocenophanes, ferrocenyl‐pyrazine, quinoline, imidazole and oxazole derivatives have been performed through aza‐Wittig reactions and by aza‐Wittig/heterocumulene‐mediated annulation, aza‐Wittig/electrocyclic ring‐closure and aza‐Wittig/intramolecular halide displacement methodologies.
Efficacy of C–N Coupling Reactions with a New Multinuclear Copper Complex Catalyst and Its Dissociation into Mononuclear Species
Authors: Zou Yan , Lin Haisheng , Maggard Paul A. , Deiters Alexander
Published: May 2011

A new tetranuclear copper(I)–pyridazine (pda)/rhenate hybrid has been synthesized under hydrothermal conditions and structurally characterized by X‐ray crystallography. The activity of this catalyst, as well as its dissociation into mononuclear species, was investigated in homogeneous C–N arylation reactions. A variety of N‐arylamides and ‐azoles were synthesized in good to excellent yields, revealing the effect of polynuclear versus mononuclear Cu complexation in this type of coupling reaction.
Association of grip strength with dementia in a Korean older population
Authors: Shin Hee‐Young , Kim Sung‐Wan , Kim Jae‐Min , Shin Il‐Seon , Yoon Jin‐Sang
Published: May 2011

Background

Several studies have found that low grip strength is associated with dementia in Western populations. However, there have been few studies in Asian populations. This cross‐sectional study aimed to examine whether grip strength is independently associated with dementia after controlling for other related factors in a Korean older population.

Methods

One thousand thirty‐eight community‐dwelling older people aged 65 or over within a defined geographic area were screened for dementia. Data on grip strength, sit‐to‐stand score, body mass index (BMI), socio‐demographic factors (age, gender, marital status, education), and medical conditions (diabetes, hypertension, heart disease, stroke) were collected. Dementia was diagnosed with the 10/66 dementia diagnostic algorithm.

Results

Eleven percent of the participants were found to have dementia. After adjustment for other factors, grip strength (per 8‐kg decrease) was independently associated with dementia (odds ratio, 1.59; 95% confidence interval, 1.19–2.14). Adjusted grip strength by BMI interaction terms showed marginal significance (p = 0.098); that is, older people with both reduced grip strength and low BMI were likely to be at higher risk for dementia.

Conclusions

Reduced grip strength was independently associated with dementia in a Korean older population. This association was partially influenced by BMI. Copyright © 2011 John Wiley & Sons, Ltd.
A simple and efficient synthesis and dynamic NMR studies of some new podands of dithiocarbamates formed from bis(naphthyl) derivatives
Authors: Shockravi Abbas , Kamali Mahmood , Sorkhei Farhad , Jafari Reza
Published: May 2011

The reaction of dithiocarbamate salts (IVa − c) with bis(naphthalene chloroacetates) (IIa,b) and bis(naphthalene ethoxybromide) (IIc) in dimethylformamide (DMF) furnished corresponding podands as Va − i in high to excellent yields. Three reacting ligands, (IIa,b) and (IIc), were obtained in the reaction of bis(naphthalene) (Ia,b) with chloroacetylchloride and 1,2‐dibromoethane. Dynamic NMR spectroscopic data of three series of podands (Va − c, Vd−f, and Vg − i) are discussed, and their free energy of activation (Δ GC≠) at coalescence temperatures are figured out. The Δ GC≠ s of these podands were attributed to conformational isomerization in the range of 14.5–18.3 kcal mol−1 due to rotation and resonance effects about thioamide CN bond. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:659–668, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20730
Synthesis of phosphorus‐containing dipeptide mimetics via the Kabachnik–Fields reaction
Authors: Todorov Petar T. , Aneva Ogniana , Naydenova Emilia D.
Published: May 2011

The synthesis of three novel dimethyl (2‐(4,4‐dimethyl‐2,5‐dioxoimidazolidin‐1‐ylamino)‐ 2‐oxoethylamino)methylphosphonate, dimethyl (1‐ (4,4‐dimethyl‐2,5‐dioxoimidazolidin‐1‐ylamino)‐4‐ methyl‐1‐oxopentan‐2‐ylamino)methylphosphonate, and dimethyl (1‐(4,4‐dimethyl‐2,5‐dioxoimidazolidin‐ 1‐ylamino)‐1‐oxo‐3‐phenylpropan‐2‐ylamino)methylphosphonate, respectively, is reported. The newly synthesized compounds were prepared via the Kabachnik–Fields reaction. Their structures have been characterized by elemental analysis, IR, and NMR (1H, 13C, and 31P) spectra. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:669–672, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20731
Fibrillar films obtained from sodium soap fibers and polyelectrolyte multilayers
Authors: Zawko Scott A. , Schmidt Christine E.
Published: May 2011

An objective of tissue engineering is to create synthetic polymer scaffolds with a fibrillar microstructure similar to the extracellular matrix. Here, we present a novel method for creating polymer fibers using the layer‐by‐layer method and sacrificial templates composed of sodium soap fibers. Soap fibers were prepared from neutralized fatty acids using a sodium chloride crystal dissolution method. Polyelectrolyte multilayers (PEMs) of polystyrene sulfonate and polyallylamine hydrochloride were deposited onto the soap fibers, crosslinked with glutaraldehyde, and then the soap fibers were leached with warm water and ethanol. The morphology of the resulting PEM structures was a dense network of fibers surrounded by a nonfibrillar matrix. Microscopy revealed that the PEM fibers were solid structures, presumably composed of polyelectrolytes complexed with residual fatty acids. These fibrillar PEM films were found to support the attachment of human dermal fibroblasts. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2011.
Arginine conjugation affects the endocytic pathways of chitosan/DNA nanoparticles
Authors: Zhang Hailing , Zhu Dunwan , Song Liping , Liu Lanxia , Dong Xia , Liu Zhenbao , Leng Xigang
Published: May 2011

Previous reports showed that arginine‐rich peptides and oligoarginines facilitated the cellular internalization of DNA and proteins. A number of studies demonstrated that arginine‐conjugated chitosan (CS)/DNA nanoparticles (ACGN) mediated significantly higher expression of the transgenes when compared with CS/DNA nanoparticles (CGN). However, the underlying mechanisms remain poorly understood. In the current study, the endocytic pathways through which cells internalize ACGN and CGN were explored by incubating the fluorescent CGN or ACGN with A10 cells in the presence of a variety of inhibitors of different endocytic pathways. The data accumulated in the current study revealed that conjugation of arginine moieties onto CS molecules enhanced the cellular uptake of the polymer/DNA nanoparticles and their transgenic efficacy, probably due to changes in the endocytic pathways, which led to the preference of internalization of ACGN by the caveolin‐mediated endocytosis in comparison with that of CGN. These findings provide further support to the previous observations that ACGN mediated much higher expression of the transgenes when compared with CGN. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2011.
Preparation, characterization, in vitro bioactivity, and osteoblast adhesion of multi‐level porous titania layer on titanium by two‐step anodization treatment
Authors: Xie Li , Liao Xiaoming , Yin Guangfu , Huang Zhongbing , Yan Danhong , Yao Yadong , Liu Wenlong , Chen Xianchun , Gu Jianwen
Published: May 2011

To combine the advantages of different electrolytes in anodic oxidation, pure titanium samples were anodized in CH3COOH electrolyte according to a novel anodizing treatment regime and then in H2SO4 electrolyte in potentialstatic mode. The in vitro bioactivity of the as‐prepared titanium samples was evaluated by simulated body fluid (SBF) test. In addition, MG63 osteoblast‐like cells were cultured on surfaces of the as‐prepared titanium samples to evaluate osteoblast adhesion ability. The titanium samples after the two‐step anodization treatment were covered by titania layers of anatase and/or rutile with several micrometres thickness and presented a multi‐level porous surface morphology consisting of interlaced grooves about 20‐μm wide overlaid with submicron scale pores. The SBF test results showed that the crystal titania layers prepared at appropriate conditions were able to induce apatite‐forming in 7 days, indicating that the abundance of surface TiOH groups and (101)‐oriented rutile structure both played important roles in in vitro bioactivity of titania layers. The cell experiment results showed that the macroscopic grooves could effectively promote osteoblast adhesion and growth and submicron scale pores might be beneficial to osteoblast adhesion. The two‐step anodization treatment might be a promising candidate for surface modification of titanium implant. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2011.
A novel strontium‐doped calcium polyphosphate/erythromycin/poly(vinyl alcohol) composite for bone tissue engineering
Authors: Song Wei , Ren Weiping , Wan Changxiu , Esquivel Amanda O. , Shi Tong , Blasier Ralph , Markel David C.
Published: May 2011

It is our goal to develop bactericidal bone scaffolds with osteointegration potential. In this study, poly(vinyl alcohol) (PVA) coating (7%) was applied to an erythromycin (EM)‐impregnated strontium‐doped calcium polyphosphate (SCPP) scaffold using a simple slurry dipping method. MicroCT analysis showed that PVA coating reduced the average pore size and the percentage of pore interconnectivity to some extent. Compressive strength tests confirmed that the PVA coating significantly increased material elasticity and slightly enhanced the scaffold mechanical strength. It was also confirmed that the PVA coatings allowed a sustained EM release that is controlled by diffusion through the intact PVA hydrogel layer, irrespective of the drug solubility. PVA coating did not inhibit the EM bioactivity when the scaffolds were immersed in simulated body fluid for up to 4 weeks. EM released from SCPP–EM–PVA composite scaffolds maintained its capability of bacterial growth (S. aureus) inhibition. PVA coating is biocompatible and nontoxic to MC3T3 preosteoblast cells. Furthermore, we found that SCPP‐EM‐PVA composite scaffolds and their eluants remarkably inhibited RANKL‐induced osteoclastogenesis in a murine RAW 264.7 macrophage cell line. Thus, this unique multifunctional bioactive composite scaffold has the potential to provide controlled delivery of relevant drugs for bone tissue engineering. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2011.
Value of contrast‐enhanced sonography in the diagnosis of peripheral intrahepatic cholangiocarcinoma
Authors: Li Chaolun , Wang Wenping , Ding Hong , Huang Beijian , Cao Jiaying , Mao Feng , Ji Zhengbiao
Published: May 2011

Background:

To illustrate contrast‐enhanced harmonic ultrasonography (CEUS) findings of peripheral intrahepatic cholangiocarcinoma (PICC) and to assess the usefulness of CEUS in the diagnosis of this disease.

Methods:

This study is a retrospective analysis of 46 patients (20 men, 26 women) with PICC who underwent both preoperative CEUS and pathologic examination. Sonographic examinations were performed with sonographic instruments equipped with low mechanical index contrast imaging software. The contrast agent SonoVue was used. The wash‐in and wash‐out features of the lesions were documented and the enhancement patterns were analyzed by visual inspection of the real‐time cine loops.

Results:

During the hepatic arterial phase of CEUS, the majority of PICC lesions (43/46, 93.5%) showed hypervascularity compared with the liver parenchyma, whereas three lesions (3/46, 6.5%) showed hypovascularity. In the portal phases, all lesions were either isoechoic or hypoechoic, while they were all hypoechoic in the late phase. Of all the hypervascular lesions, 48.8% (21/43) showed diffuse enhancement and 51.2% (22/43) showed rim‐like or thick, rim‐like enhancement. In 62.8% (27/43) of cases, progressive dendritic and centripetal fill‐in of the contrast agent was observed. There were 83.7% (36/43) of hypervascular nodules showing heterogeneous enhancement during peak contrast enhancement of the lesions. CEUS provided clearer visualization of lesion margins than did conventional sonography.

Conclusions:

CEUS examination yields some specific findings that are useful in the diagnosis of PICC. © Wiley Periodicals, Inc. J Clin Ultrasound 2011
Sonographic visualization of a scapular body fracture: A case report
Authors: McCrady Bradley M. , Schaefer Michael P.
Published: May 2011

We report the case of a scapular body fracture that was visualized with ultrasound and confirmed with three‐dimensional CT. Ultrasound examination showed a comminuted fracture along the lateral border of the left scapula. We suggest scanning of the scapula, particularly the lateral scapula border, in patients with a history of shoulder trauma who continue to have symptoms in the shoulder girdle. © 2011 Wiley Periodicals, Inc. J Clin Ultrasound, 2011
An alternate route to the synthesis of imidazo[1,2‐a]quinolines using I2‐NaI reagent
Authors: Upadhyay Shraddha , Chandra Atish , Singh Seema , Singh Radhey M.
Published: May 2011

A new and a facile route to the synthesis of imidazo[1,2‐a]quinolines has been described via iodocyclization reaction of 2‐allylaminoquinoline derivatives using I2‐NaI reagent. J. Heterocyclic Chem., (2011).
Solvent‐free three‐component synthesis of 7‐aryl‐1,1‐dioxothieno[3,2‐b]pyran derivatives catalyzed by ammonium acetate
Authors: Yao Changsheng , Feng Xiaodong , Wang Cuihua , Jiang Bei , Yu Chenxia , Wang Xiangshan , Li Tuanjie , Tu Shujiang
Published: May 2011

An efficient synthesis of 7‐aryl‐1,1‐dioxothieno[3,2‐b]pyran derivatives via the reaction of aryl aldehyde, tetrahydrothiophene‐3‐one‐1,1‐dioxide and malononitrile or ethyl 2‐cyanoacetate was performed at room temperature catalyzed by ammonium acetate under solvent‐free conditions. Compared with the conventional methods, this protocol features mild reaction conditions, high yields, and eco‐friendliness. J. Heterocyclic Chem., (2011).
Root colonization of a rice growth promoting strain of Enterobacter cloacae
Authors: Shankar Manoharan , Ponraj Paramasivan , Ilakkiam Devaraj , Gunasekaran Paramasamy
Published: June 2011

Enterobacter cloacae GS1 was isolated by in‐planta enrichment of a rice rhizoplane bacterial community. It displayed strong seed adherence ability (2.5 × 105 cfu/seed) and colonized rice roots reaching up to 1.65 × 109 cfu/g of fresh root weight in a gnotobiotic root colonization system. E. cloacae GS1 was motile, able to solubilize tricalcium phosphate, and produced indole acetic acid like substances (15 μg/ml). As an introduced bioinoculant in non‐sterile soil, E. cloacae GS1 colonized rice roots and significantly improved the fresh weight, root length, shoot length, and nitrogen content in inoculated rice seedlings as compared to uninoculated controls. This isolate was tagged with green fluorescent protein and various stages of root colonization in gnotobiotic hydroponic environment and non‐sterile soil environment were followed by fluorescence microscopy. Owing to its effective root colonizing ability and growth promoting potential, Enterobacter cloacae GS1 is a promising symbiotic bioinoculant for rice. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Requirements for sulfur in cell density‐independent induction of luminescence in Vibrio fischeri under nutrient‐starved conditions
Authors: Tabei Yosuke , Era Mariko , Ogawa Akane , Morita Hiroshi
Published: June 2011

Despite the universal requirement for sulfur in living organisms, it is not known whether the luminescence of Vibrio fischeri is sulfur‐dependent and how sulfur affects the intensity of its luminescence. In this study, we investigated the requirement for sulfur in V. fischeri luminescence under nutrient‐starved conditions. Full induction of V. fischeri luminescence required MgSO4; in artificial seawater cultures that lacked sufficient MgSO4, its luminescence was not fully induced. This induction of luminescence was not dependent on autoinduction because the cell density of V. fischeri did not reach the critical threshold concentration. In addition to MgSO4, this cell density‐independent luminescence was induced or maintained by nontoxic concentrations of l‐cysteine, sulfate, sulfite, and thiosulfate. Moreover, the addition of N ‐3‐oxo‐hexanoyl homoserine lactone and N ‐octanoyl homoserine lactone, which are known autoinducers in V. fischeri, did not induce luminescence under these conditions. This result suggested that the underlying mechanism of luminescence may be different from the known autoinduction mechanism. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pleistocene forest on Tenerife's southern coast: a case study of Montaña Negra
Authors: Pannell Claire L. , Gray Alan , Zalasiewicz Jan A. , Branney Michael J. , Curry Gordon B.
Published: May 2011

Montaña Negra is a 121 m cinder cone in the Bandas del Sur region of southern Tenerife. Formed in the Middle Pleistocene, it comprises alternating phonolitic pumice deposits and scoria layers; the latter are extremely fossiliferous with good taphonomical fidelity. 40Ar/39Ar age determination provides new dates of 302 ± 7.6 ka and 299.9 ± 11.4 ka for the Lower and Upper Aldea Blanca pumice fall deposits, respectively. This chronological constraint allows comparison of the palaeo‐habitat with the global climate at the time of pyroclastic activity. Abundant terrestrial gastropod species and rare disarticulated Coleoptera fragments are to be found. The occurrence of the endemic semi‐slug genus Plutonia (Family Vitrinidae) is significant in indicating a woodland habitat in the region during the Middle Pleistocene. We suggest that this may have been forest, possibly dominated by laurel, which is in stark contrast to the present‐day semi‐desert. Copyright © 2011 John Wiley & Sons, Ltd.
Optimized mobile phase for CEC of acetylsalicylic acid and its impurities using a methacrylate‐based monolithic column
Authors: Tanret Indiana , Mangelings Debby , Vander Heyden Yvan
Published: May 2011

In the past few years, monolithic methacrylate‐based columns have attracted some attention in separation science. The mobile‐phase optimization on these columns for drug analysis has not yet been thoroughly examined. This paper evaluates the separation of acetylsalicylic acid and its impurities as a case study. First, the best pH was determined as 2.3. Methacrylate‐based phases can be employed at such pH because they remain charged, necessary to generate electro‐osmotic flow. Then, a suitable solvent strength was determined. Trifluoroacetic acid (0.1%) was added to the mobile phase to improve peak shapes. The optimal organic modifier composition was then determined, using isoeluotropic mobile phases, based on the theory of Snyder's solvent triangle. Quadratic models were built to predict the retention of the compounds at all mobile‐phase compositions within the triangle. The predictions were tested and found appropriate. Eventually, a baseline separation of acetylsalicylic acid and its impurities was not obtained. However, it could be concluded that one can optimize the mobile phase on methacrylate‐based monolithic columns in CEC using Snyder's solvent triangle approach.
Exploring the efficacy of a residential treatment program incorporating cognitive processing therapy‐cognitive for veterans with PTSD and traumatic brain injury
Authors: Chard Kathleen M. , Schumm Jeremiah A. , McIlvain Susan M. , Bailey Gregory W. , Parkinson R. Bruce
Published: May 2011

As the numbers of military personnel participating in the wars in Afghanistan and Iraq continue to grow, the percentage of individuals who return with both a traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD) also increases. Although there appears to be significant overlap in the symptoms resulting from PTSD and TBI, the best course of treatment remains an area of controversy. The authors present initial findings from a Veterans Administration residential program for comorbid PTSD and TBI. Forty‐two participants completed a program comprising psychoeducational groups and cognitive skill building that was augmented with a modification of standard cognitive processing therapy. The results suggest that residential programs that incorporate this form of cognitive therapy can anticipate meaningful participation from patients, and that it may be an effective approach to treat PTSD in individuals with a history of TBI.
Free‐Standing Films of Semifluorinated Block Copolymer Brushes from Layer‐by‐Layer Polyelectrolyte Macroinitiators
Authors: Estillore Nicel C. , Advincula Rigoberto C.
Published: May 2011

Free‐standing semifluorinated polymer brushes from layer‐by‐layer (LbL) macroinitiators are demonstrated. LbL deposition of macroinitiators is followed by surface‐initiated atom transfer radical polymerization (SI‐ATRP). Increasing the number of LbL macroinitiator layers increases grafting density and thickness. The SI‐ATRP is conducted by first polymerizing a block of polystyrene followed by the semifluorinated poly‐2,2,2‐trifluoroethyl methacrylate block. Solvent selective response is investigated by AFM imaging and water contact angle measurements. Specifically, the solvent response of the semifluorinated block copolymer brushes exhibits alternate selectivity to cyclohexane and trifluorotoluene. Solvent responsive free‐standing films are also demonstrated.

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