bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation and the Physico‐chemical Properties of the Tropospheric Aerosol
Authors: Winkler Peter , Kaminski Uwe 
Published: May 2011

AbstractAn evaluation of the long‐term records of aerosol and meteorological parameters at the Meteorological Observatory of Hamburg reveals that particle production in the nucleation mode is stimulated by solar radiation and is enhanced by elevated SO2 or NOx concentrations. While the particle number increases, their average sulfate or nitrate content per particle decreases with increasing sunshine. In the accumulation and coarse mode sulfate production takes place even at relative humidities above 80% but no nitrate production, while in the nucleation mode, nitrate production occurs at high humidities but only a weak sulfate production. The nitrate to sulfate ratio shows a winter maximum and a summer minimum in the course of the year and a long term increase over the past 6 years in both size ranges. The sulfate content of the Aitken particles shows a broad maximum in autumn. Coagulation causes a rapid mass transfer from the nucleation to the accumulation mode at high concentrations (>100 cm−3) of large particles. In the long‐term trend, the aerosol mass showed an increase between 1976 and 1986 and a decrease since then but the number concentration of the large particles (0.1 ≤ r ≤ 1 μm) is still increasing. This aerosol fraction has the longest atmospheric residence time. The Aitken particle number has reduced since 1980 most probably caused by a reduction of the SO2 concentration. With respect to physico‐chemical properties, the particle growth with relative humidity and the problem of internal or external mixing are discussed.
Global Changes of Aerosols – Ground Based Monitoring of the Optical Thickness in Polar Regions and Central Europe
Authors: Leiterer Ulrich , Weller Michael , Herber Andreas 
Published: May 2011

AbstractOptical thickness measurements in north polar, south polar and Central European regions are presented and discussed in comparison with earlier values. Actinometer measurements of the integral optical thickness in the Arctic (Franz‐Joseph‐Land) from 1933 to 1942 show an average level of about 0.22 and only minor changes between spring and summer and from year to year. Since 1955 the spring values show a pronounced increase to 0.3 in 1985. In contrast to this behaviour, the levels in Antarctica (Mirny) are much lower (around 0.18) and fairly stable between 1957 and 1990 except for two time periods with strong volcanic activities with peaks up to 0.28. – Spectral aerosol thickness data at 500 and 1000 nm for Antarctica (G. Forster) from 1955 to 1990 indicate volcanic activity markedly with data rising from a level around 0.03 to two maxima of about 0.12. In March 1989, the boundary layer extinction coefficient at 500 nm in the Arctic reached the 79‐fold of the Antarctic and the 2.5‐fold of the Central Europe values at Lindenberg. The very high winter and spring aerosol extinction coefficients in the Arctic result from long‐range transport and gas‐to‐particle conversion of NOx and SO2.
Photochemistry of Atmospheric Trace Gases
Authors: Schurath U. 
Published: May 2011

AbstractThe complex scheme of atmospheric radical chain reactions is driven by a relatively small number of photodissociation processes. The most important ones in the troposphere are the formation of O(1D) by the photolysis of ozone (frequency J1), and the photolysis of NO2 (frequency J2). It is shown that uncertainties in J1 and J2 lead to large uncertainties in model‐predicted species concentrations, particularly in OH levels. Methods of calculating/measuring J1 and J2 will be discussed.
N2O Formation in the Reactive Collisional Quenching of NO3* and NO2* by N2
Authors: Zellner R. , Hartmann D. , Rosner I. 
Published: May 2011

AbstractThe formation of N2O in the reactive collisional quenching of NO3 (Ã2E') and NO2 (Ã2B1, 2B2) by N2 at 298 K has been determined using a dye laser excitation technique combined with product accumulation/g.c. analysis. The absolute yield of N2O is found to be proportional to the number of photons absorbed (Npe) into non‐dissociative states of the electronically excited species. The relative N2O yields (ΔN2O/Npe) have been determined as ϕ1 = (1.4 ± 0.6) · 10−2 and ϕ2 = (4.0 ± 2.0) · 10−4 for the quenching of NO3* and NO2*, respectively. As a consequence of high pumping rates of NO3* and NO2* in the daytime atmosphere these processes represent a significant in situ chemical source of atmospheric N2O.
Spectroscopy and Photochemistry of Chlorine Dioxide
Authors: Vaida V. , Richard E. C. , Jefferson A. , Cooper L. A. , Flesch R. , Rühl E. 
Published: May 2011

AbstractThe photoreactivity of chlorine dioxide excited in the near ultraviolet is reexamined in this paper. The results of this study are used to evaluate the possible role that the photochemistry of OClO may play in polar ozone depletion. – The study reported here involves high resolution spectroscopic and photofragment experiments of isolated gas phase OClO and of OClO clustered with water. The results show that excitation in the near ultraviolet of the A(2A2) ← X(2B1) transition leads to both dissociation to form vibrationally excited ClO and O, and to rearrangement which ultimately leads to Cl and O2. Formation of Cl and O2 may contribute to catalytic polar ozone depletion. The mechanism and quantum yield for these two photoreactions are discussed. The quantum yields for the two excited state reactions are very sensitive to perturbations by intermolecular interactions. The heterogeneous photoreactivity of OClO is probed in (H2O)n clusters.
Product Quantum Yields for the 350 nm Photodecomposition of Pyruvic Acid in Air
Authors: Berges Markus G. M. , Warneck Peter 
Published: May 2011

AbstractQuantum yields for the products CH3CHO, CO2 and CH3COOH in the 350 nm photodecomposition of pyruvic acid are 0.48 ± 0.01, 1.27 ± 0.18 and 0.14, respectively, as measured in air at atmospheric pressure. In the presence of NO2 the quantum yield for CH3CHO was reduced to 0.30 ± 0.04 and peroxyacetyl nitrate was formed with a quantum yield of 0.15 ± 0.02. This is taken to indicate the formation of acetyl radicals in one of the primary processes.
A Fast Algorithm to Calculate the Photonflux in Optically Dense Media for Use in Photochemical Models
Authors: Röth Ernst‐Peter 
Published: May 2011

AbstractA photon flux model is described which determines the photodissociation coefficients for the simulation of atmospheric chemistry with a very fast algorithm. Emphasis is laid on the calculation of the radiative transfer in optically thick media, e.g. in clouds. The concept of Kubelka and Munk [1] has been adapted to atmospheric conditions. The algorithm is described in detail, and general aspects of the radiative transfer in clouds are presented. To prove the accuracy of the algorithm, the results are compared to those gained by a more sophisticated model.
Reactions of Ozone with Unsaturated Organic Compounds
Authors: Treacy Jack , Hag Mohamed El , O'Farrell Denis , Sidebottom Howard 
Published: May 2011

AbstractRate constants for the gas‐phase reactions of ozone with a series of alkenes have been determined using a conventional static system. Ozone loss was monitored in excess of the hydrocarbon and rate data measured at 1 atmosphere total pressure over the temperature range 240–324 K. The Arrhenius parameters obtained are discussed in terms of structure‐reactivity relationships. Product studies have been carried out for the reaction of O3 with the conjugated dienes, 1,3‐butadiene, 2‐methyl‐1,3‐butadiene (isoprene) and 2,3‐dimethyl‐1,3‐butadiene in air. The results provide information on the decomposition pathways for the primary ozonides and the relative importance of ozone addition to the two double‐bonds in isoprene.
Gas Phase Studies on Chloryl Chloride, ClClO2
Authors: Müller Holger S. P. , Willner Helge 
Published: May 2011

AbstractClClO2 has been generated by reacting FClO2 with BCl3 or HCl in the gas phase at room temperature. It is also formed in the reaction of photolytically generated Cl‐atoms with ClO2. One weak and three strong fundamentals as well as two weak combination bands were observed in the mid infrared region. In the UV‐region ClClO2 strongly absorbs, exhibiting maxima at 231 and 296 nm with σ = 1.3 and 1.5 · 10−17 cm2 molecule−1. Decomposition of ClClO2 follows second order with a halflife of 60s at 1.0 mbar partial and 4 mbar total pressure, resulting in ClO2 and Cl2.
Effect of Temperature on the Dissociative and Nondissociative Electron Attachment to Freons
Authors: Christophorou L. G. , Datskos P. G. , Carter J. G. 
Published: May 2011

AbstractThe attachment of slow electrons to freons (including many atmospheric halocarbons) depends rather strongly on the gas temperature. In general, as the temperature increases, dissociative electron attachment increases and nondissociative electron attachment decreases; the former behavior is principally due to increase in autodissociation and the latter principally due to increase in autodetachment of the transient anion.
The Arrhenius Equation: Limits of Validity under Extreme Reaction Conditions
Authors: Stiller W. 
Published: May 2011

AbstractPhoton‐induced molecular dissociation increases the portion of radical reactions which in general can be treated in the framework of chemical equilibrium kinetics of the translational degrees of freedom of the reagents. In particular an “inversion” of the Arrhenius equation gives a reactive “Arrhenius” cross section which shows a wide (but limited) spectrum of possibilities describing bimolecular gas phase reactions in the framework of Arrhenius kinetics. The occurrence of charged particles and energy‐rich cosmic, solar and magnetospheric species and the presence of electromagnetic fields lead to nonequilibrium situations which have to be described by the chemical nonequilibrium kinetics deviating from Arrhenius kinetics.
Aqueous‐Phase Chemical Processes in Deliquescent Seasalt Aerosols
Authors: Chameides W. L. , Stelson A. W. 
Published: May 2011

AbstractThe aqueous‐phase chemistry of deliquescent seasalt aerosols in the remote marine boundary layer is investigated with a steady‐state box model. The model simulates the scavenging of soluble and reactive gaseous species by the seasalt aerosols, the chemical reactions of these species and seasalt ions in the deliquescent solution, and changes in the aerosol composition that occur as a result of these processes. Because of the alkalinity of seasalt, the calculations indicate that deliquescent seasalt aerosols are strongly buffered and as a result their pH remains close to 8 until the amount of acid added to the aerosol solution exceeds the alkalinity. The oxidation of chloride by O3 as well as by free radicals are found to proceed at extremely slow rates and thus these reactions can not explain the high chloride deficits recently observed over the North Atlantic Ocean. On the other hand, the oxidation of dissolved SIV by O3 in seasalt aerosols is found to proceed at an extremely high rate and appears to explain the observations of nss‐SO42‐ in seasalt aerosols over the Noth Atlantic Ocean. The high rate of SIV oxidation is found to proceed until the amount of nss‐SO42‐ generated in the aerosol is sufficiently large to overwhelm the buffering capacity and lower the pH below 5.5. As a result, the calculations suggest a strong coupling between the cycles of S and alkalinity in the marine boundary layer that may act to limit the generation of cloud condensation nuclei from the oxidation of biogenic S emissions.
Laser‐Based Studies of Reactions of the Nitrate Radical in Aqueous Solution
Authors: Exner M. , Herrmann H. , Zellner R. 
Published: May 2011

AbstractA new experimental technique for temperature dependent studies of the kinetics of the nitrate radical (NO3) in aqueous solution has been developed. In this technique NO3 is produced by excimer laser photolysis of peroxodisulfate anions at 351 nm in the presence of excess nitrate and detected by time‐resolved long‐path laser absorption using the 632.8 nm line of a HeNe‐laser. — For the generation reaction of NO3, viz. (1) SO4− + NO3− SO42‐ + NO3 a rate constant of k1 = (5.0 ± 0.5) · 104 l mol · s at T = 298 K and zero ionic strength was found. For the reactions (2) NO3 + OH− NO3− OH and (3) NO3 + Cl− NO3− + Cl rate coefficients of k2 = (8.2 ± 0.9) · 107 and k3. = (1.0 ± 0.2) · 107 l/mol · s were determined at T = 298 K. In temperature dependent experiments the Arrhenius expressions k2(T) = (8.1 ± 0.4) · 1011 exp[‐(2700 ± 400)K/T] l/mol · s and k3(T) = (1.9 ± 0.2) · 1013 exp[‐(4300 ± 500) K/T] l/mol · s were derived. ‐ The rate constant of the reaction of NO3 with dissolved sulfur (IV) has been studied over a range of pH‐values and temperature. For the reactions with SO2(aq) (4). and HSO3− (5) rate coefficients of k4 = (2.3 ± 0.5) · 108 and k5 = (1.4 ± 0.1) · 109 l/mol · s, respectively, at 298 K were obtained. The corresponding temperature dependences are described by: k4(T) = (5.6 ± 0.7) · 1013 exp[‐(3700 ± 1100)K/T] l/mol · s and k5(T) = (1.1 ± 0.2) · 1012 exp[‐(2000 ± 400)K/T] l mol · s. For the reaction of NO3 with SO32‐ (6) a rate constant of k6 = (3.0 ± 0.4) · 108 l/mol · s was derived at T = 278 K.
Ozone Destruction on Powders
Authors: Alebić‐Juretić A. , Cvitaš T. , Klasinc L. 
Published: May 2011

AbstractThe destruction of ozone on silica‐gel, alumina, sodium chloride, calcite, Saharan sand and wood ash as model powders was studied in a fluidized bed reactor. An elevated ambient concentration of ozone (100 ppb) in the filtered air stream was applied during the experiments. The relative effectiveness of ozone destruction was in the order alumina > wood ash > silica‐gel, followed by Saharan sand > calcite > sodium chloride. The implication of this result on ozone measurements in particle‐rich atmospheres is discussed.
On the Variability of the Stratosphere in the Arctic Regions in Winter
Authors: Labitzke K. 
Published: May 2011

AbstractThe arctic stratosphere is much more variable in winter, and from one winter to another, than is the antarctic stratosphere. The latter stays cold and intense through the winter, whereas the former is subject to minor and major midwinter warmings. During the major midwinter warmings the arctic warms up and the cyclonic vortex — normally centered near the North Pole — divides into two centers which move south while an anticyclone becomes established near the pole. — Because the antarctic polar cyclonic vortex remains cold and centered near the pole till the end of winter, conditions favorable for the development of an ozone hole exist when the sun returns in spring. This is in contrast to the disturbed conditions in the arctic which usually keep the temperature at a level that is not conducive to large‐scale destruction of ozone.
Luminescence properties of a nanoporous freshwater diatom
Authors: Goswami Bondita , Choudhury Amarjyoti , Buragohain Alak K. 
Published: May 2011

ABSTRACTFreshwater diatom frustules show special optical properties. In this paper we observed luminescence properties of the freshwater diatom Cyclotella meneghiniana. To confirm the morphological properties we present scanning electron microscopy (SEM) images. X‐ray diffraction (XRD) studies were carried out to visualize the structural properties of the frustules, confirming that silica present in diatom frustules crystallizes in an α‐quartz structure. Study of the optical properties of the silica frustules of diatoms using ultra‐violet‐visible (UV‐vis) spectroscopy and photoluminescence spectroscopy confirmed that the diatom C. meneghiniana shows luminescence in the blue region of the electromagnetic spectrum when irradiated with UV light. This property of diatoms can be exploited to obtain many applications in day‐to‐day life. Also, using time‐resolved photoluminescence spectroscopy (TRPL) it was confirmed that this species of diatom shows bi‐exponential decay. Copyright © 2011 John Wiley & Sons, Ltd.
Recurrent groin hernia surgery
Authors: Sevonius D , Gunnarsson U , Nordin P , Nilsson E , Sandblom G 
Published: May 2011

Abstract

Background
The reoperation rate after recurrent groin hernia surgery is more than twice that recorded for primary groin hernia procedures. The aim was to define the outcome from routine redo hernia surgery by analysing a large population-based cohort from a national hernia register.

Methods
All recurrent groin hernia operations registered in the Swedish Hernia Register from 1992 to 2008 were analysed using multivariable analysis with stratification for preceding repair.

Results
Altogether 174 527 hernia operations were recorded in the Swedish Hernia Register between 1992 and 2008, including 19 582 reoperations. The preceding repair was included in the register for 5565 of these recurrent repairs. With laparoscopic repair as reference standard, the hazard ratio for recurrence was 2·55 (95 per cent confidence interval 1·66 to 3·93) after sutured repair, 1·53 (1·20 to 1·95) after Lichtenstein repair, 2·31 (1·76 to 3·03) after plug repair, 1·36 (0·95 to 1·94) after open preperitoneal mesh and 3·08 (2·22 to 4·29) after other repairs. Laparoscopic and open preperitoneal repair were associated with a lower risk of reoperation following a preceding open repair (P &lt; 0·001), but no technique differed significantly from the others following a preceding preperitoneal repair.

Conclusion
The laparoscopic and the open preperitoneal mesh methods of repair for recurrent groin hernias were associated with the lowest risk of reoperation. Although the method of repair in previous surgery must be considered, these techniques are the preferred methods for recurrent groin hernia surgery.
Systematic review of outcome of downstaging hepatocellular cancer before liver transplantation in patients outside the Milan criteria
Authors: Gordon-Weeks A N , Snaith A , Petrinic T , Friend P J , Burls A , Silva M A 
Published: May 2011

AbstractBackgroundThe aim of this systematic review was to assess the evidence on tumour downstaging before liver transplantation in patients with hepatocellular carcinoma (HCC) initially staged beyond the Milan criteria.MethodsMEDLINE (from 1952), Embase (from 1980) and the Cochrane Library were searched. The review included cohort studies that reported the outcomes of patients with HCC outside the Milan criteria who underwent downstaging before transplantation.ResultsEight studies met the inclusion criteria and included a total of 720 patients who underwent transplantation following downstaging after initial presentation with disease outside the Milan criteria. The rate of successful downstaging varied from 24 to 69 per cent of patients. Reported survival rates ranged from 82 to 100 per cent, 79 to 100 per cent and 54·6 to 94 per cent at 1, 3 and 5 years respectively. These were comparable with results for patients presenting within the Milan criteria.ConclusionSuccessful downstaging of HCC to within the Milan criteria is feasible in a proportion of patients. Absolute and disease-free survival rates in patients transplanted following downstaging are comparable to those in patients within the Milan criteria.
Development and validation of a highly sensitive LC‐MS/MS method for quantitation of dexlansoprazole in human plasma: application to a human pharmacokinetic study
Authors: Hotha Kishore Kumar , Vijaya Bharathi D. , Jagadeesh B. , Ravindranath L. K. , Jaya Veera K. N. , Venkateswarulu V. 
Published: May 2011

ABSTRACTA highly sensitive, specific and simple LC‐MS/MS method was developed for the simultaneous estimation of dexlansoprazole (DEX) with 50 μL of human plasma using omeprazole as an internal standard (IS). The API‐4000 LC‐MS/MS was operated under multiple reaction‐monitoring mode using electrospray ionization. A simple liquid–liquid extraction process was used to extract DEX and IS from human plasma. The total run time was 2.00 min and the elution of DEX and IS occurred at 1.20 min. This was achieved with a mobile phase consisting of 0.2% ammonia–acetonitrile (20:80, v/v) at a flow rate of 0.50 mL/min on an X‐terra RP 18 (50 × 4.6 mm, 5 µm) column. The developed method was validated in human plasma with a lower limit of quantitation of 2 ng/mL for DEX. A linear response function was established for the range of concentrations 2.00–2500.0 ng/mL (r > 0.998) for DEX. The intra‐ and inter‐day precision values for DEX met the acceptance criteria as per FDA guidelines. DEX was stable in the battery of stability studies, viz. bench‐top, auto‐sampler and freeze–thaw cycles. The developed assay method was applied to an oral bioequivalence study in humans. Copyright © 2011 John Wiley & Sons, Ltd.
In vivo metabolism study of polygalic acid in rat using HPLC‐ESI‐MSn
Authors: Ling Yun , Wu Bin , Wang Ke , Liu Huihui , Chen Luying , Fan Mingsong , Sun Zhaolin , Huang Chenggang 
Published: May 2011

ABSTRACTA very simple and direct method has been established for the determination of polygalic acid and its metabolites in rat urine based on HPLC coupled with electrospray ionization multi‐stage tandem mass spectrometry (HPLC‐ESI‐MSn). The rats were administered a single dose (100 mg/kg) of polygalic acid by oral gavage. The urine samples were collected and purified through a C18 solid‐phase extraction cartridge, and then these pretreated samples were injected into a reversed‐phase C18 column with a gradient elution program, whereas acetonitrile–0.5% aqueous formic acid was used as mobile phase and detected by an on‐line MS/MS system. As a result, the parent drug and its four metabolites were identified and characterized in rat urine for the first time by comparing their changes in molecular mass (ΔM), retention times and full‐scan MSn spectra with those of the parent drug. A possible metabolic pathway of polygalic acid was investigated and proposed. More importantly, the results demonstrated that the newly developed method (HPLC‐ESI‐MSn) was sensitive, simple and suitable for the determination of polygalic acid and its metabolites in biological samples. Copyright © 2011 John Wiley & Sons, Ltd.
The impact of unsuccessful percutaneous coronary intervention on short‐ and long‐term prognosis in STEMI and NSTEMI
Authors: Mazurek Michal , Kowalczyk Jacek , Lenarczyk Radoslaw , Swiatkowski Andrzej , Kowalski Oskar , Sedkowska Agnieszka , Was Tomasz , Swierad Marcin , Pruszkowska‐Skrzep Patrycja , Kurek Tomasz , Jedrzejczyk Ewa , Polonski Lech , Kalarus Zbigniew 
Published: May 2011

AbstractObjectives: To compare the impact of the efficacy of percutaneous coronary intervention (PCI) on prognosis in ST and non‐ST elevation myocardial infarction (STEMI and NSTEMI) patients with respect to infarct‐related artery (IRA). Background: The significance of the efficacy of PCI in STEMI and NSTEMI depending on the type of IRA has yet to be clarified. Methods: Study population consisted of 2,179 STEMI and 554 NSTEMI consecutive patients treated with urgent PCI. The efficacy of PCI (TIMI [thrombolysis in myocardial infarction] 3 vs. TIMI < 3) was assessed with regard to the type of IRA (left anterior descending artery, circumflex artery [Cx] or right coronary artery). The mean follow‐up was 37.5 months. Results: The rate of unsuccessful PCI was similar in STEMI and NSTEMI irrespectively of IRA (14.1 vs. 17.7%; P = 0.062). In STEMI, unsuccessful PCI was associated with significantly higher early (23.1 vs. 5.6%; P < 0.001) and late (29.9 vs. 12.8%; P < 0.001) mortality regardless of IRA. In NSTEMI, the inefficacious PCI significantly increased early (19.0% vs. 0.9%; P < 0.001) and late (27.3% vs. 6.3%; P < 0.001) mortality only in patients with Cx‐related infarction. Unsuccessful PCI of IRA was an independent risk factor for death in STEMI (HR 1.64; P < 0.05), but not in NSTEMI (P = 0.64). Further analysis showed that whilst unsuccessful PCI of any vessel in STEMI is an independent risk factor for death, in NSTEMI this applies to unsuccessful PCI of Cx only. Conclusions: The significance of unsuccessful PCI of IRA seems to be different in STEMI and NSTEMI. Unsuccessful PCI is an independent risk factor for death in STEMI regardless of IRA and in NSTEMI with the involvement of Cx. © 2010 Wiley‐Liss, Inc.