bluuebunny/crossref_metadata_2025 huggingface dataset:
The detection of post-monsoon tropospheric ozone variability over south Asia using IASI data
Authors: Barret B. , Le Flochmoen E. , Sauvage B. , Pavelin E. , Matricardi M. , Cammas J. P.
Published: September 2011

Abstract. The ozone (O3) variability over south Asia during the 2008 post-monsoon season has been assessed using measurements from the MetOP-A/IASI instrument and O3 profiles retrieved with the SOftware for a Fast Retrieval of IASI Data (SOFRID). The information content study and error analyses carried out in this paper show that IASI Level 1 data can be used to retrieve tropospheric O3 columns (TOC, surface-225 hPa) and UTLS columns (225–70 hPa) with errors smaller than 20%. Validation with global radiosonde O3 profiles obtained during a period of 6 months show the excellent agreement between IASI and radiosonde for the UTLS with correlation coefficient R > 0.91 and good agreement in the troposphere with correlation coefficient R > 0.74. For both the UTLS and the troposphere Relative Standard Deviations (RSD) are lower than 23%. Comparison with in-situ measurements from the MOZAIC program around Hyderabad demonstrates that IASI is able to capture the TOC inter and intra-seasonal variability in central India. Nevertheless, the agreement is mitigated by the fact that the smoothing of the true O3 profiles by the retrieval results in a reduction of the TOC variability detected by IASI relative to the variability observed by in situ instruments. The post-monsoon temporal variability of the vertical profile of O3 around Hyderabad has been investigated with MOZAIC observations. These observations from airborne instruments show that tropospheric O3 is steadily elevated during most of the studied period with the exception of two sharp drops following the crossing of tropical storms over India. Lagrangian simulations with the FLEXPART model indicate that elevated O3 concentrations in the middle troposphere near Hyderabad are associated with the transport of UTLS air-masses that have followed the Subtropical Westerly Jet (SWJ) and subsided over northern India together with boundary layer polluted air-masses transported from the Indo-gangetic plain by the north-easterly trades. Low O3 concentrations result from the uplift and westward transport of pristine air-masses from the marine boundary layer of the Bay of Bengal by tropical storms. In order to extend the analysis of tropospheric O3 variability to the whole of south Asia, we have used IASI-SOFRID O3 data. We show that IASI O3 data around Hyderabad were able to capture the fast variability revealed by MOZAIC. Furthermore, their spatio-temporal coverage demonstrates that the behaviour of tropospheric O3 observed near Hyderabad extended over most of central and south India and part of the Bay of Bengal. This result highlights the ability of the IASI sensor to capture fast changes in chemical composition related to dramatic tropical weather conditions.
Source attribution of Bornean air masses by back trajectory analysis during the OP3 project
Authors: Robinson N. H. , Newton H. M. , Allan J. D. , Irwin M. , Hamilton J. F. , Flynn M. , Bower K. N. , Williams P. I. , Mills G. , Reeves C. E. , McFiggans G. , Coe H.
Published: September 2011

Abstract. Atmospheric composition affects the radiative balance of the Earth through the creation of greenhouse gases and the formation of aerosols. The latter interact with incoming solar radiation, both directly and indirectly through their effects on cloud formation and lifetime. The tropics have a major influence on incoming sunlight however the tropical atmosphere is poorly characterised, especially outside Amazonia. The origins of air masses influencing a measurement site in a protected rainforest in Borneo, South East Asia, were assessed and the likely sources of a range of trace gases and particles were determined. This was conducted by interpreting in situ measurements made at the site in the context of ECMWF backwards air mass trajectories. Two different but complementary methods were employed to interpret the data: comparison of periods classified by cluster analysis of trajectories, and inspection of the dependence of mean measured values on geographical history of trajectories. Sources of aerosol particles, carbon monoxide and halocarbons were assessed. The likely source influences include: terrestrial organic biogenic emissions; long range transport of anthropogenic emissions; biomass burning; sulphurous emissions from marine phytoplankton, with a possible contribution from volcanoes; marine production of inorganic mineral aerosol; and marine production of halocarbons. Aerosol sub- and super-saturated water affinity was found to be dependent on source (and therefore composition), with more hygroscopic aerosol and higher numbers of cloud condensation nuclei measured in air masses of marine origin. The prevailing sector during the majority of measurements was south-easterly, which is from the direction of the coast closest to the site, with a significant influence inland from the south-west. This analysis shows that marine and terrestrial air masses have different dominant chemical sources. Comparison with the AMAZE-08 project in the Amazon basin shows Bornean composition to arise from a different, more complex mixture of sources. In particular sulphate loadings are much greater than in Amazonia which is likely to mainly be the result of the marine influence on the site. This suggests that the significant region of the tropics made up of island networks is not well represented by extrapolation from measurements made in the Amazon. In addition, it is likely that there were no periods where the site was influenced only by the rainforest, with even the most pristine inland periods showing some evidence of non-rainforest aerosol. This is in contrast to Amazonia which experienced periods dominated by rainforest emissions.
Odin-OSIRIS stratospheric aerosol data product and SAGE III intercomparison
Authors: Bourassa A. E. , Rieger L. A. , Lloyd N. D. , Degenstein D. A.
Published: September 2011

Abstract. The scattered sunlight measurements made by the Optical Spectrograph and InfraRed Imaging System (OSIRIS) on the Odin spacecraft are used to retrieve vertical profiles of stratospheric aerosol extinction at 750 nm. The recently released OSIRIS Version 5 data product contains the first publicly released stratospheric aerosol extinction retrievals, and these are now available for the entire Odin mission, which extends from the present day back to launch in 2001. A proof-of-concept study for the retrieval of stratospheric aerosol extinction from limb scatter measurements was previously published and the Version 5 data product retrievals are based on this work, but incorporate several important improvements to the algorithm. One of the primary changes is the use of a new retrieval vector that greatly improves the sensitivity to aerosol scattering by incorporating a forward modeled calculation of the radiance from a Rayleigh atmosphere. Additional improvements include a coupled retrieval of the effective albedo, a new method for normalization of the measurement vector to improve signal-to-noise, and the use of an initial guess that is representative of very low background aerosol loading conditions, which allows for maximal retrieval range. Furthermore, the Version 5 data set is compared to SAGE III 755 nm extinction profiles during the almost four years of mission overlap from 2002 to late 2005. The vertical structure in coincident profile measurements is well correlated and the statistics on a relatively large set of tight coincident measurements show agreement between the measurements from the two instruments to within approximately 10 % throughout the 15 to 25 km altitude range, which covers the bulk of the stratospheric aerosol layer for the mid and high latitude cases studied here.
Analysis of high mass resolution PTR-TOF mass spectra from 1,3,5-trimethylbenzene (TMB) environmental chamber experiments
Authors: Müller M. , Graus M. , Wisthaler A. , Hansel A. , Metzger A. , Dommen J. , Baltensperger U.
Published: September 2011

Abstract. A series of 1,3,5-trimethylbenzene (TMB) photo-oxidation experiments was performed in the 27-m3 Paul Scherrer Institute environmental chamber under various NOx conditions. A University of Innsbruck prototype high resolution Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-TOF) was used for measurements of gas and particulate phase organics. The gas phase mass spectrum displayed ~200 ion signals during the TMB photo-oxidation experiments. Molecular formulas CNmHnNoOp were determined and ion signals were separated and grouped according to their C, O and N numbers. This allowed to determine the time evolution of the O:C ratio and of the average carbon oxidation state OSC of the reaction mixture. Both quantities were compared with master chemical mechanism (MCMv3.1) simulations. The O:C ratio in the particle phase was about twice the O:C ratio in the gas phase. Average carbon oxidation states of secondary organic aerosol (SOA) samples OSCSOA were in the range of −0.34 to −0.31, in agreement with expected average carbon oxidation states of fresh SOA (OSC = −0.5 − 0).
The global atmospheric budget of ethanol revisited
Authors: Kirstine W. V. , Galbally I. E.
Published: September 2011

Abstract. Ethanol is an important biogenic volatile organic compound, which is increasingly used as a fuel for motor vehicles; therefore, an improved understanding of its atmospheric cycle is important. In this paper we use three sets of observational data, measured emissions of ethanol from living plants, measured concentrations of ethanol in the atmosphere and measured hydroxyl concentrations in the atmosphere (by methyl chloroform titration), to make two independent estimates related to the rate of cycling of ethanol through the atmosphere. The observational bases are small and the uncertainties large; however, the measurements identified above are the only experimentally determined information available on atmospheric ethanol. In the first estimate, simple calculations give the emission rate of ethanol from living plants as 26 (range, 10–38) Tg y−1. This contributes significantly to the total global ethanol source of 42 (range, 25–56) Tg y−1. In the second estimate, the total losses of ethanol from the global atmosphere are 70 (range, 50–90) Tg y−1, with about three-quarters of the ethanol removed by reaction with hydroxyl radicals in the gaseous and aqueous phases of the atmosphere, and the remainder lost through wet and dry deposition to land. These values of both the source of ethanol from living plants and the removal of atmospheric ethanol via oxidation by hydroxyl radicals (derived entirely from observations) are significantly larger than those in recent literature. We suggest that a revision of the estimate of global ethanol emissions from plants to the atmosphere to a value comparable with this analysis is warranted.
An improved tropospheric NO2 column retrieval algorithm for the Ozone Monitoring Instrument
Authors: Boersma K. F. , Eskes H. J. , Dirksen R. J. , van der A R. J. , Veefkind J. P. , Stammes P. , Huijnen V. , Kleipool Q. L. , Sneep M. , Claas J. , Leitão J. , Richter A. , Zhou Y. , Brunner D.
Published: September 2011

Abstract. We present an improved tropospheric nitrogen dioxide column retrieval algorithm (DOMINO v2.0) for OMI based on better air mass factors (AMFs) and a correction for across-track stripes resulting from calibration errors in the OMI backscattered reflectances. Since October 2004, NO2 retrievals from the Ozone Monitoring Instrument (OMI), a UV/Vis nadir spectrometer onboard NASA's EOS-Aura satellite, have been used with success in several scientific studies focusing on air quality monitoring, detection of trends, and NOx emission estimates. Dedicated evaluations of previous DOMINO tropospheric NO2 retrievals indicated their good quality, but also suggested that the tropospheric columns were susceptible to high biases (by 0–40%), probably because of errors in the air mass factor calculations. Here we update the DOMINO air mass factor approach. We calculate a new look-up table (LUT) for altitude-dependent AMFs based on more realistic atmospheric profile parameters, and include more surface albedo and surface pressure reference points than before. We improve the sampling of the TM4 model, resulting in a priori NO2 profiles that are better mixed throughout the boundary layer. We evaluate the NO2 profiles simulated with the improved TM4 sampling as used in the AMF calculations and show that they are highly consistent with in situ NO2 measurements from aircraft during the INTEX-A and INTEX-B campaigns in 2004 and 2006. Our air mass factor calculations are further updated by the implementation of a high-resolution terrain height and a high-resolution surface albedo climatology based on OMI measurements. Together with a correction for across-track stripes, the overall impact of the improved terrain height and albedo descriptions is modest (<5%) on average over large polluted areas, but still causes significant changes locally. The main changes in the DOMINO v2.0 algorithm follow from the new LUT and the improved TM4 sampling that results in more NO2 simulated aloft, where sensitivity to NO2 is higher, and amount to reductions in tropospheric NO2 columns of up to 20% in winter, and 10% in summer over extended polluted areas. We investigate the impact of aerosols on the NO2 retrieval, and based on a comparison of concurrent retrievals of clouds from OMI and aerosols from MODIS Aqua, we find empirical evidence that OMI cloud retrievals are sensitive to the presence of scattering aerosols. It follows that an implicit correction for the effects of aerosols occurs through the aerosol-induced cloud parameters in DOMINO, and we show that such an empirical correction amounts to a 20 %AMF reduction in summer and ±10% changes in winter over the eastern United States.
iGen 0.1: the automated generation of a parameterisation of entrainment in marine stratocumulus
Authors: Tang D. F. , Dobbie S.
Published: September 2011

Abstract. In a previous paper we described a new technique for automatically generating parameterisations using a program called iGen. iGen generates parameterisations by analysing the source code of a~high resolution model that resolves the physics to be parameterised. In order to demonstrate that this technique scales up to deal with models of realistic complexity we have used iGen to generate a parameterisation of entrainment in marine stratocumulus. We describe how iGen was used to analyse the source code of an eddy resolving model (ERM) and generate a parameterisation of entrainment velocity in marine stratocumulus in terms of the large-scale state of the boundary layer. The parameterisation was tested against results from the DYCOMS-II intercomparison of ERM models and iGen's parameterisation of mean entrainment velocity was found to be 5.27 × 10−3 ± 0.62 × 10−3 m s−1 compared to 5.2 × 10−3 ± 0.8 × 10−3 m s−1 for the DYCOMS-II ensemble of large eddy simulation (LES) models.
CAM-chem: description and evaluation of interactive atmospheric chemistry in CESM
Authors: Lamarque J.-F. , Emmons L. K. , Hess P. G. , Kinnison D. E. , Tilmes S. , Vitt F. , Heald C. L. , Holland E. A. , Lauritzen P. H. , Neu J. , Orlando J. J. , Rasch P. , Tyndall G.
Published: September 2011

Abstract. We discuss and evaluate the representation of atmospheric chemistry in the global Community Atmosphere Model (CAM) version 4, the atmospheric component of the Community Earth System Model (CESM). We present a variety of configurations for the representation of tropospheric and stratospheric chemistry, wet removal, and online and offline meteorology. Results from simulations illustrating these configurations are compared with surface, aircraft and satellite observations. Overall, the model indicates a good performance when compared to observations. Major biases include a negative bias in the high-latitude CO distribution and a positive bias in upper-tropospheric/lower-stratospheric ozone, especially when online meteorology is used. The CAM-chem code as described in this paper, along with all the necessary datasets needed to perform the simulations described here, are available for download at http://www.cesm.ucar.edu.
The application of the Modified Band Approach for the calculation of on-line photodissociation rate constants in TM5: implications for oxidative capacity
Authors: Williams J. E. , Strunk A. , Huijnen V. , van Weele M.
Published: September 2011

Abstract. A flexible and explicit on-line parameterization for the calculation of tropospheric photodissociation rate constants (J-values) has been integrated into the global Chemistry Transport Model TM5. Here we provide a comprehensive description of this Modified Band Approach (MBA) including details of the optimization procedure employed, the methodology applied for calculating actinic fluxes, the photochemical reaction data used for each chemical species and the parameterizations adopted for improving the description of scattering and absorption by clouds and aerosols. The resulting J-values change markedly throughout the troposphere when compared to the offline approach used to date, with significant increases in the boundary layer and upper troposphere. Conversely, for the middle troposphere a reduction in the actinic flux results in a decrease in J-values. Integrating effects shows that application of the MBA introduces seasonal dependent differences in important trace gas oxidants. Tropospheric ozone changes by ±5% in the seasonal mean mixing ratios throughout the troposphere, which induces changes of ±15% in tropospheric OH. In part this is due to an increase in the re-cycling efficiency of nitrogen oxides. The overall increase in northern hemispheric tropospheric ozone strengthens the oxidizing capacity of the troposphere significantly and reduces the lifetime of CO and CH4 by ~5% and ~4%, respectively. Changes in the tropospheric CO burden, however, are limited to a few percent due to competing effects. Comparing the distribution of tropospheric ozone in the boundary layer and middle troposphere against observations in Europe shows there are improvements in the model performance during boreal winter in the Northern Hemisphere near regions affected by high nitrogen oxide emissions. Monthly mean total columns of nitrogen dioxide and formaldehyde also compare more favorably against OMI and SCIAMACHY total column observations.
Catchment classification by runoff behaviour with self-organizing maps (SOM)
Authors: Ley R. , Casper M. C. , Hellebrand H. , Merz R.
Published: September 2011

Abstract. Catchments show a wide range of response behaviour, even if they are adjacent. For many purposes it is necessary to characterise and classify them, e.g. for regionalisation, prediction in ungauged catchments, model parameterisation. In this study, we investigate hydrological similarity of catchments with respect to their response behaviour. We analyse more than 8200 event runoff coefficients (ERCs) and flow duration curves of 53 gauged catchments in Rhineland-Palatinate, Germany, for the period from 1993 to 2008, covering a huge variability of weather and runoff conditions. The spatio-temporal variability of event-runoff coefficients and flow duration curves are assumed to represent how different catchments "transform" rainfall into runoff. From the runoff coefficients and flow duration curves we derive 12 signature indices describing various aspects of catchment response behaviour to characterise each catchment. Hydrological similarity of catchments is defined by high similarities of their indices. We identify, analyse and describe hydrologically similar catchments by cluster analysis using Self-Organizing Maps (SOM). As a result of the cluster analysis we get five clusters of similarly behaving catchments where each cluster represents one differentiated class of catchments. As catchment response behaviour is supposed to be dependent on its physiographic and climatic characteristics, we compare groups of catchments clustered by response behaviour with clusters of catchments based on catchment properties. Results show an overlap of 67% between these two pools of clustered catchments which can be improved using the topologic correctness of SOMs.
99MTc-MAG3 Diuretic Renography in Assessment of Obstructive Uropathy. The new test F+10SP: a Step Ahead in the Differential Diagnosis
Authors: Vittori Matteo , D'addessi Alessandro , Pinto Francesco , Tartaglione Girolamo , Bassi Pierfrancesco
Published: September 2011

Background

Dilation of the renal pelvis is a problem Urologists have often to deal with. One of the key aspects is to clear if the dilation is the consequence of an obstruction to the outflow or a simple anatomic variant. Aim of this study was to compare two diuretic renographic procedures, F-15 vs the new procedure F+10SP (Seated Position) in a group of hydronephrotic patients, in order to increase the accuracy in the differential diagnosis between non-obstructive and obstructive dilation.

Materials and Methods

34 Patients (14 male, 20 female, 18–71 yrs range), 27 pts having an unilateral hydronephrosis and 7 pts a bilateral hydronephrosis diagnosed by ultrasound, were enclosed in the study. They were subjected to two 99mTc-MAG3 diuretic renography with furosemide consecutively, with different modalities: 1) 40 mg of furosemide were administered IV to patient in supine position 15 minutes before tracer injection (Test F-15, by English); 2) the new procedure: 20 mg of furosemide were administered IV to patient in Seated Position (SP), 10 minutes after tracer injection during dynamic acquisition (Test F+10 SP). The average interval between the two tests was 7 days. Two different physicians analyzed all the tests. The results were classified as: non-obstruction (only F+10SP can distinguish between normal and dilated without obstruction), obstruction, equivocal and not applicable.

Results

Among the 68 renal units (RU) included in the analysis, the F+10SP test showed normal findings in 21 RU (30,8%), dilation without obstruction in 21 RU (30,8%), obstruction in 25 RU (36.8%) and equivocal result in 1 RU. The F-15 renography showed non-obstructive results in 35 RU (51.5%), obstruction in 20 RU (29.4%) and equivocal findings in 11 RU (16.1%); the test was not applicable in 2 RU (2.9%) due to insufficient renal function. Side effects reported for the F-15 renogram were hypotension in 1 patient, renal colic in 3 patients, bladder filling in 13 patients, disruption because of voiding in 4 patients. No complications were observed during or after the F+10SP renography. The 20 RU diagnosed with obstruction at the F-15 test were considered obstructed also at the F+10SP test.

Conclusions

The “equivocal” test rate lowered from 16% for the F-15 test to less than 1.5% for the new F+10 SP test. The F+10SP procedure is easy, well tolerated, time saving and seems to be a more reliable tool in assessment of obstructive uropathy in adults.
The wisdom of the inner life: Meeting oneself through meditation and music
Authors: Sussman Abraham , Kossak Mitchell
Published: September 2011

This chapter discusses the psychology of the inner life and how music as meditation can tap into unitive states of being that lead to inner wisdom.
Our healing is next to the wound: Endarkened feminisms, spirituality, and wisdom for teaching, learning, and research
Authors: Okpalaoka Chinwe L. , Dillard Cynthia B.
Published: September 2011

This chapter explores how the spiritual and cultural contexts of wisdom and Black women's knowing and dialogues on race can facilitate cross‐cultural and within‐group understandings of race, gender, and identity in teaching and learning.
Mentoring men for wisdom: Transforming the pillars of manhood
Authors: Parks Daloz Laurent A.
Published: September 2011

This chapter offers insights into mentoring men toward wisdom and is based on the notion that growth into a more grounded and connected wisdom entails transformation of the pillars of traditional masculinity: procreating, providing, and protecting.
Teaching, learning, and the human quest: Wisdom
Authors: Jarvis Peter
Published: September 2011

This chapter reflects on the human quest to understand both the “why” and the “how” of existence itself and suggests that while we can be taught about wisdom, we can only learn to be wise.
Thermoelectric Nanostructures: From Physical Model Systems towards Nanograined Composites
Authors: Nielsch Kornelius , Bachmann Julien , Kimling Johannes , Böttner Harald
Published: September 2011

Thermoelectric materials could play an increasing role for the efficient use of energy resources and waste heat recovery in the future. The thermoelectric efficiency of materials is described by the figure of merit ZT = (S2σT)/κ (S Seebeck coefficient, σ electrical conductivity, κ thermal conductivity, and T absolute temperature). In recent years, several groups worldwide have been able to experimentally prove the enhancement of the thermoelectric efficiency by reduction of the thermal conductivity due to phonon blocking at nanostructured interfaces. This review addresses recent developments from thermoelectric model systems, e.g. nanowires, nanoscale meshes, and thermionic superlattices, up to nanograined bulk‐materials. In particular, the progress of nanostructured silicon and related alloys as an emerging material in thermoelectrics is emphasized. Scalable synthesis approaches of high‐performance thermoelectrics for high‐temperature applications is discussed at the end.
Anion‐π‐Wechselwirkungen ins rechte Licht gerückt
Authors: Frontera Antonio , Gamez Patrick , Mascal Mark , Mooibroek Tiddo J. , Reedijk Jan
Published: September 2011

Die supramolekulare Chemie ist ein Gebiet, das die Beziehung zwischen molekularer Struktur und molekularer Funktion erforscht. Es ist die Chemie der nichtkovalenten Bindung, die die Grundlage der spezifischen Erkennung und der Transport‐ und Regulationsvorgänge bildet, die biologische Vorgänge antreiben. Die klassischen Konstruktionsprinzipien der supramolekularen Chemie umfassen starke, gerichtete Wechselwirkungen wie Wasserstoffbrücken, Halogenbrücken und Kation‐π‐Komplexbildung, aber auch weniger gerichtete Kräfte wie Ionenpaarung, π‐π‐, solvophobe und Van‐der‐Waals‐Wechselwirkungen. In den letzten Jahren wurde auch die Anion‐π‐Wechselwirkung (eine anziehende Kraft zwischen einem elektronenarmen aromatischen System und einem Anion) als bis dahin unerforschte nichtkovalente Bindung erkannt, und ihre Natur wurde experimentell und theoretisch untersucht. Die Konstruktion selektiver Anionenrezeptoren und ‐kanäle auf der Grundlage dieser Wechselwirkung war ein wichtiger Fortschritt auf dem Gebiet der supramolekularen Chemie. Ziele dieses Aufsatzes sind: 1) aktuelle Vorstellungen über die Natur dieser Wechselwirkung zu diskutieren, 2) eine Übersicht über die wichtigsten experimentellen Arbeiten zu geben, in denen Anion‐π‐Bindung nachgewiesen wurden, und 3) Einblicke in die Richtungsabhängigkeit von Anion‐π‐Kontakten in Kristallstrukturen zu geben.
Ionische Flüssigkeiten als hypergole Treibstoffe
Authors: Zhang Yanqiang , Gao Haixiang , Joo Young‐Hyuk , Shreeve Jean'ne M.
Published: September 2011

Noch immer werden in Treibstoffsystemen Hydrazin und dessen Derivate als Brennstoffe eingesetzt, obwohl es sich dabei um karzinogene und toxische Substanzen handelt, die recht hohe Dampfdrücke haben und kostenintensive Sicherheitsvorkehrungen erfordern. Erst 2008 wurde entdeckt, dass sich ionische Flüssigkeiten mit Dicyanamid‐Anionen beim Kontakt mit Oxidationsmitteln spontan entzünden können (Hypergolie). Solche Flüssigkeiten sind wenig flüchtig sowie thermisch und chemisch recht stabil und verfügen oft über große Flüssigkeitsbereiche, was die Anwendung in Zweikomponententreibstoffen unter vielfältigen Bedingungen ermöglichen könnte. Eine neue Familie von in Wasser synthetisierbaren Dicyanoboraten wird präsentiert, die nahezu alle Anforderungen an leistungsstarke Treibstoffe erfüllt.
Strategies and Tactics for the Metal‐Directed Synthesis of Rotaxanes, Knots, Catenanes, and Higher Order Links
Authors: Beves Jonathon E. , Blight Barry A. , Campbell Christopher J. , Leigh David A. , McBurney Roy T.
Published: September 2011

More than a quarter of a century after the first metal template synthesis of a [2]catenane in Strasbourg, there now exists a plethora of strategies available for the construction of mechanically bonded and entwined molecular level structures. Catenanes, rotaxanes, knots and Borromean rings have all been successfully accessed by methods in which metal ions play a pivotal role. Originally metal ions were used solely for their coordination chemistry; acting either to gather and position the building blocks such that subsequent reactions generated the interlocked products or by being an integral part of the rings or “stoppers” of the interlocked assembly. Recently the role of the metal has evolved to encompass catalysis: the metal ions not only organize the building blocks in an entwined or threaded arrangement but also actively promote the reaction that covalently captures the interlocked structure. This Review outlines the diverse strategies that currently exist for forming mechanically bonded molecular structures with metal ions and details the tactics that the chemist can utilize for creating cross‐over points, maximizing the yield of interlocked over non‐interlocked products, and the reactions‐of‐choice for the covalent capture of threaded and entwined intermediates.
Tensile properties of denture base resin reinforced with various esthetic fibers
Authors: Demir Hakan , Dogan Orhan Murat , Dogan Arife
Published: September 2011

This study was conducted to determine the reinforcement effect of five types of esthetic fibers on the tensile properties of a conventional denture base resin. E‐glass, polyester, rayon, nylon 6, and nylon 6/6 fibers were cut into 2, 4, and 6 mm lengths and added into resin randomly at a concentration of 3% by weight. For each formulation, five tensile specimens, as well as control specimens without fibers, were prepared in a dumbbell shape using a stainless steel mold, constructed according to ASTM Standard D638M‐91a. Tensile properties were evaluated by using a universal testing machine. Surfaces of the tensile sections were also observed under the scanning electron microscope (SEM). Tensile strength of the specimens reinforced with fibers in varying lengths was found to be lower than that of the unreinforced control group. Among the trial groups, the specimens reinforced with 6 mm long polyester fibers showed the highest tensile strength. All the SEM fractographs indicated both weak adhesion and pull out of fibers from the matrix. None of the incorporated esthetic fibers appeared to improve tensile strength of the resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The effect of sulfonation treatment on the structure and properties of isotactic polypropylene fibers prior to the carbonization stage
Authors: Karacan Ismail , Benli Hüseyin
Published: September 2011

The effect of sulfonation treatment was investigated on the molecular structure and mechanical properties of isotactic polypropylene fibers extruded at a take up speed of 2500 m/min. It was found that at extensive sulfonation times, the sulfonated structure showed the characteristic features of carbonized structure as indicated by the results of the density and the X‐ray diffraction measurements. Mechanical properties of the sulfonated samples were found to be adversely affected by the sulfonation conditions. Scanning electron microscopy observations showed surface irregularities at low sulfonation times and fiber fractures at high sulfonation times. Polarized infrared spectroscopy measurements analysed by curve fitting procedure showed increasing molecular orientation of long helical chain segments represented by the IR band at 841 cm−1 whereas amorphous structure represented by the IR band at 2723 cm−1 showed gradual loss of orientation with the progress of sulfonation. IR bands assigned to the sulfonic acid groups formed during sulfonation treatment showed perpendicular polarization and low molecular orientation characteristics indicating the initiation and the development of crosslinking process being perpendicular to the fiber axis direction. Analysis of the equatorial X‐ray diffraction traces showed the loss of crystallinity where the paracrystalline phase disappeared faster than the crystalline α‐monoclinic phase. During the sulfonation treatment, content of amorphous phase showed gradual increase in line with decreasing crystallinity. In accordance with the loss of crystallinity, apparent crystallite sizes corresponding to the 110, 040 and 130 planes of the α‐monoclinic phase also decreased gradually with increasing sulfonation time. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
New polymer syntheses part: 54 novel conducting polymers and copolymers based on 4‐Teriary butyl‐cyclohexanone moiety in the main chain
Authors: Aly Kamal I.
Published: September 2011

A new interesting class of conducting polymer and copolymers based on 4‐teriary butyl‐cyclohexanone in the main chain has been synthesized by solution polycodensation of terephthalaldehyde with 4‐teriary butyl‐cyclohexanone and/or cycloalkanone derivatives. The model compound I was synthesized from the 4‐teriary butyl‐cyclohexanone with benzaldehyde, and its structure was confirmed by elemental and spectral analyses. The resulting polymer and copolymers were characterized by elemental and spectral analyses including Fourier transform infrared spectrometer (FT‐IR) and nuclear magnetic resonance (1H‐NMR), beside solubility and viscometry measurements. The thermal properties of those polymer and copolymers were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) measurements and correlated to their structural units. X‐ray analysis showed that it has some degree of crystallinity in the region 2θ = 5–60°. The UV–visible spectra of some selected polymers were measured in dimethyl sulfoxide (DMSO) solution and showed absorption bands in the range 253–398 nm, due to n–π* and π–π* transition. The morphological properties of selected examples were tested by scanning electron microscope (SEM). Moreover, the electrical conductivities and the doping with iodine were tested. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
A Multistage Geophysical Approach to Detecting and Interpreting Archaeological Features at the LeBus Circle, Bourbon County, Kentucky
Authors: Henry Edward R.
Published: September 2011

Magnetic gradiometry and in‐phase electromagnetic induction (EM) instruments were employed during a geophysical survey to identify archaeological features at an Adena circular ditch and embankment earthwork site. Three features identified in the geophysical survey were selected for further geophysical examination because of their shape, spatial arrangement, and differences in the gradiometer and EM data. Downhole magnetic susceptibility was used to explore the subsurface shape of these features and to identify the presence of magnetic variations within them. Excavation of these features exposed a buried ground surface below the earthwork's embankment, a midden‐like soil in the ditch, and a large pit situated over a spring/seep inside the earthwork. Magnetic susceptibility data were collected on open wall profiles of excavation units with a KT9 kappameter. Pairing the geophysical results and excavation profiles helped separate a lightly burned ground surface from a buried A horizon below the embankment, map the buried A horizon beneath areas where the embankment is now destroyed, and separate natural from cultural fill episodes inside the pit feature. Correlations between the magnetic susceptibility data and drawn profiles identified specific cultural contexts for radiocarbon dating. The radiocarbon chronology of the site indicates the earthwork was constructed during Middle Adena ritual development (150 bc to ad 1), a time marked by increasing ritual diversity and the appearance of circular structures used in mortuary ritual. This research also demonstrated that the Woodland earthwork was reused by Late Fort Ancient peoples after approximately ad 1450. Copyright © 2011 John Wiley & Sons, Ltd.
Mitonuclear match: Optimizing fitness and fertility over generations drives ageing within generations
Authors: Lane Nick
Published: September 2011

Many conserved eukaryotic traits, including apoptosis, two sexes, speciation and ageing, can be causally linked to a bioenergetic requirement for mitochondrial genes. Mitochondrial genes encode proteins involved in cell respiration, which interact closely with proteins encoded by nuclear genes. Functional respiration requires the coadaptation of mitochondrial and nuclear genes, despite divergent tempi and modes of evolution. Free‐radical signals emerge directly from the biophysics of mosaic respiratory chains encoded by two genomes prone to mismatch, with apoptosis being the default penalty for compromised respiration. Selection for genomic matching is facilitated by two sexes, and optimizes fitness, adaptability and fertility in youth. Mismatches cause infertility, low fitness, hybrid breakdown, and potentially speciation. The dynamics of selection for mitonuclear function optimize fitness over generations, but the same selective processes also operate within generations, driving ageing and age‐related diseases. This coherent view of eukaryotic energetics offers striking insights into infertility and age‐related diseases.
Relevance of magnetic resonance imaging-detected pelvic sidewall lymph node involvement in rectal cancer
Authors:   MERCURY Study Group, Brown G
Published: September 2011

Background

The significance of magnetic resonance imaging (MRI)-suspected pelvic sidewall (PSW) lymph node involvement in rectal cancer is uncertain.

Methods

Magnetic resonance images were reviewed retrospectively by specialist gastrointestinal radiologists for the presence of suspicious PSW nodes. Scans and outcome data were from patients with biopsy-proven rectal cancer and a minimum of 5 years' follow-up in the Magnetic Resonance Imaging and Rectal Cancer European Equivalence Study. Overall disease-free survival (DFS) was analysed using the Kaplan–Meier product-limit method and stratified according to preoperative therapy. Binary logistic regression was used to match patients for propensity of clinical and staging characteristics, and further survival analysis was carried out to determine associations between suspicious PSW nodes on MRI and survival outcomes.

Results

Of 325 patients, 38 (11·7 per cent) had MRI-identified suspicious PSW nodes on baseline scans. Such nodes were associated with poor outcomes. Five-year DFS was 42 and 70·7 per cent respectively for patients with, and without suspicious PSW nodes (P < 0·001). Among patients undergoing primary surgery, MRI-suspected PSW node involvement was associated with worse 5-year DFS (31 versus 76·3 per cent; P = 0·001), but the presence of suspicious nodes had no impact on survival among patients who received preoperative therapy. After propensity matching for clinical and tumour characteristics, the presence of suspicious PSW nodes on MRI was not an independent prognostic variable.

Conclusion

Patients with suspicious PSW nodes on MRI had significantly worse DFS that appeared improved with the use of preoperative therapy. These nodes were associated with adverse features of the primary tumour and were not an independent prognostic factor.
Novel Allene Oxide Synthase Products Formed via Favorskii‐Type Rearrangement: Mechanistic Implications for 12‐Oxo‐10,15‐phytodienoic Acid Biosynthesis
Authors: Grechkin Alexander N. , Lantsova Natalia V. , Toporkova Yana Y. , Gorina Svetlana S. , Mukhitova Faina K. , Khairutdinov Boulat I.
Published: September 2011

The allene oxide synthase (AOS) pathway is widespread in plants. Its products, such as cyclopentenone 12‐oxo‐10,15‐phytodienoic acid (12‐oxo‐PDA) and related jasmonates, play important biological roles in plants. We found that 12‐oxo‐PDA in some plant tissues co‐occur with an unknown minor oxylipin 1. In vitro incubations of AOSs with α‐linolenic acid 13(S)‐hydroperoxide reliably afforded 1 along with 12‐oxo‐PDA and α‐ketol. A similar oxylipin 3 was formed during the AOS conversions of γ‐linolenic acid 9(S)‐hydroperoxide. Linoleic acid hydroperoxides formed neither products similar to 1 and 3 nor cyclopentenones. Oxylipins 1 and 3 were purified and identified as the products of Favorskii‐type rearrangement, (2′Z,4Z)‐2‐(2′‐pentenyl)‐4‐tridecene‐1,13‐dioic acid and (2′Z,4Z)‐2‐(2′‐octenyl)‐4‐decene‐1,10‐dioic acid, respectively. Detection of Favorskii products 1 and 3 demonstrates that cyclopropanones are short‐lived AOS products along with allene oxides. The observed parallels between the Favorskii product 1 and 12‐oxo‐PDA formation suggests that cyclopropanone is either a byproduct or a precursor of 12‐oxo‐PDA.
A Synthetic Mirror Image of Kalata B1 Reveals that Cyclotide Activity Is Independent of a Protein Receptor
Authors: Sando Lillian , Troeira Henriques Sónia , Foley Fiona , Simonsen Shane M. , Daly Norelle L. , Hall Kristopher N. , Gustafson Kirk R. , Aguilar Marie‐Isabel , Craik David J.
Published: September 2011

Featuring a circular, knotted structure and diverse bioactivities, cyclotides are a fascinating family of peptides that have inspired applications in drug design. Most likely evolved to protect plants against pests and herbivores, cyclotides also exhibit anti‐cancer, anti‐HIV, and hemolytic activities. In all of these activities, cell membranes appear to play an important role. However, the question of whether the activity of cyclotides depends on the recognition of chiral receptors or is primarily modulated by the lipid‐bilayer environment has remained unknown. To determine the importance of lipid membranes on the activity of the prototypic cyclotide, kalata B1, we synthesized its all‐D enantiomer and assessed its bioactivities. After the all‐D enantiomer had been confirmed by 1H NMR to be the structural mirror image of the native kalata B1, it was tested for anti‐HIV activity, cytotoxicity, and hemolytic properties. The all‐D peptide is active in these assays, albeit with less efficiency; this reveals that kalata B1 does not require chiral recognition to be active. The lower activity than the native peptide correlates with a lower affinity for phospholipid bilayers in model membranes. These results exclude a chiral receptor mechanism and support the idea that interaction with phospholipid membranes plays a role in the activity of kalata B1. In addition, studies with mixtures of L and D enantiomers of kalata B1 suggested that biological activity depends on peptide oligomerization at the membrane surface, which determines affinity for membranes by modulating the association–dissociation equilibrium.
Gas‐Phase Photooxidation of Alkenes by V‐Doped TiO2‐MCM‐41: Mechanistic Insights of Ethylene Photooxidation and Understanding the Structure–Activity Correlation
Authors: Bhattacharyya Kaustava , Varma Salil , Tripathi Arvind Kumar , Vinu Ajayan , Tyagi Avesh Kumar
Published: September 2011

Nanoparticles of Ti0.95V0.05O2 were found to be impregnated in the hexagonal channels of the MCM‐41 host, with a distribution of some particles on the surface, thus leading to an effective variation in the particle size as a function of loading host MCM‐41 matrix. These catalysts were subjected to the photocatalytic degradation of alkenes under the ambient conditions in which the photocatalytic activity varied as a function of the loading percentage of Ti0.95V0.05O2 in the host MCM‐41.This is explained in light of the structure–activity correlation, and the better catalytic activity can be attributed to an electronic interaction between the host and guest molecules, as established from X‐ray photoelectron spectroscopy. To understand the mechanistic aspect of the photooxidation of ethylene on the vanadium‐doped titania dispersed in the MCM‐41 matrix, extensive in situ FTIR experiments were undertaken. The intermediate species produced on bare Ti0.95V0.05O2 are different from that produced on the Ti0.95V0.05O2/MCM‐41 surface. Moreover, different intermediates were produced during ethylene oxidation under UV and visible irradiation, thus leading to different rates. The ethylene decomposition over bare Ti0.95V0.05O2 occurs by means of formation of ethoxy groups, transformed to acetaldehyde or enolates, subsequently to acetates, and then to CO2 under both UV and visible irradiation. However, in the case of Ti0.95V0.05O2/MCM‐41 catalyst with UV irradiation, the adsorbed acetaldehyde thus formed undergoes aldol condensation over the Lewis acid sites to lead to the formation of crotonaldehyde, which is subsequently oxidized to acetate and consequently to CO2. It was observed that during visible irradiation labile ethyl acetate is produced either by the Tischenko reaction or by the reaction between the labile acetic acid and the unreacted ethoxy groups. The ethyl acetate produces acetic acid monomer, which is oxidized to CO2. Furthermore, in this work the effects of particle size on the intermediate species were also studied.
Insights into the Acid–Base Properties of PtIV–Diazidodiam(m)inedihyroxido Complexes from Multinuclear NMR Spectroscopy
Authors: Ronconi Luca , Pizarro Ana M. , McQuitty Ruth J. , Sadler Peter J.
Published: September 2011

Platinum(IV) am(m)ine complexes are of interest as potential anticancer pro‐drugs, but there are few reports of their acid–base properties. We have studied the acid–base properties of three photoactivatable anticancer platinum(IV)‐diazidodiam(m)ine complexes (cis,trans,cis‐[PtIV(N3)2(OH)2(NH3)2], trans,trans,trans‐[PtIV(N3)2(OH)2(NH3)2], and cis,trans‐[PtIV(N3)2(OH)2(en)]) using multinuclear NMR methods and potentiometry. In particular, the combination of both direct and indirect techniques for the detection of 15N signals has allowed changes of the chemical shifts to be followed over the pH range 1–11; complementary 14N NMR studies have been also carried out. A distinct pKa value of approximately 3.4 was determined for all the investigated complexes, involving protonation/deprotonation reactions of one of the axial hydroxido groups, whereas a second pH‐dependent change for the three complexes at approximately pH 7.5 appears not to be associated with a loss of an am(m)ine or hydroxido proton from the complex. Our findings are discussed in comparison with the limited data available in the literature on related complexes.
Domino Friedel–Crafts‐Type Cyclizations of Difluoroalkenes Promoted by the α‐Cation‐Stabilizing Effect of Fluorine: An Efficient Method for Synthesizing Angular PAHs
Authors: Fuchibe Kohei , Jyono Hideharu , Fujiwara Masaki , Kudo Takao , Yokota Misaki , Ichikawa Junji
Published: September 2011

In order to synthesize polycyclic aromatic hydrocarbons with nonlinear arrangements (angular PAHs), acid‐promoted domino cyclizations of 1,1‐difluoroalk‐1‐enes and 1,1‐difluoroalka‐1,3‐dienes were studied. 1,1‐Difluoroalkenes, each bearing two aryl substituents, were regioselectively protonated with FSO3H⋅SbF5 to generate fluorine‐stabilized carbocations, which readily underwent domino Friedel–Crafts‐type cyclizations to give carbocycles based on 6/n/m/6 ring systems (n,m=5–7) in good to high yields. Protonation of 1,1‐difluoroalka‐1,3‐dienes took place at their electron‐rich methylene (CH2) carbon atoms in the presence of milder acids such as camphorsulfonic acid and trifluoromethanesulfonic acid. Domino cyclizations of the resulting fluorine‐stabilized allylic carbocations afford carbocycles based on 6/6/6/6 or 6/6/5/6 ring systems in high yields.