bluuebunny/crossref_metadata_2025 huggingface dataset:
On the modeling of planetary plasma environments by a fully kinetic electromagnetic global model HYB-em
Authors: Pohjola V. , Kallio E.
Published: June 2010

Abstract. We have developed a fully kinetic electromagnetic model to study instabilities and waves in planetary plasma environments. In the particle-in-a-cell (PIC) model both ions and electrons are modeled as particles. An important feature of the developed global kinetic model, called HYB-em, compared to other electromagnetic codes is that it is built up on an earlier quasi-neutral hybrid simulation platform called HYB and that it can be used in conjunction with earlier hybrid models. The HYB models have been used during the past ten years to study globally the flowing plasma interaction with various Solar System objects: Mercury, Venus, the Moon, Mars, Saturnian moon Titan and asteroids. The new stand-alone fully kinetic model enables us to (1) study the stability of various planetary plasma regions in three-dimensional space, (2) analyze the propagation of waves in a plasma environment derived from the other global HYB models. All particle processes in a multi-ion plasma which are implemented on the HYB platform (e.g. ion-neutral-collisions, chemical processes, particle loss and production processes) are also automatically included in HYB-em model. In this brief report we study the developed approach by analyzing the propagation of high frequency electromagnetic waves in non-magnetized plasma in two cases: We study (1) expansion of a spherical wave generated from a point source and (2) propagation of a plane wave in plasma. The analysis shows that the HYB-em model is capable of describing these space plasma situations successfully. The analysis also suggests the potential of the developed model to study both high density-high magnetic field plasma environments, such as Mercury, and low density-low magnetic field plasma environments, such as Venus and Mars.
A new technique for determining orientation and motion of a 2-D, non-planar magnetopause
Authors: Blagau A. , Klecker B. , Paschmann G. , Haaland S. , Marghitu O. , Scholer M.
Published: June 2010

Abstract. For a four-point mission like Cluster, the differences in position and time when the satellites detect the magnetopause or any other discontinuity, can be used to infer the discontinuity local orientation, thickness and motion. This timing technique, commonly assuming a planar geometry, offers an independent check for various single-spacecraft techniques. In the present paper we propose an extension of the timing method, capable of determining in a self-consistent way the macroscopic parameters of a two-dimensional, non-planar discontinuity. Such a configuration can be produced by a local bulge or indentation in the magnetopause, or by a large amplitude wave traveling on this surface, and is recognized in Cluster data when the single spacecraft techniques provide different individual normals contained roughly in the same plane. The model we adopted for the magnetopause assumes a layer of constant thickness of either cylindrical or parabolic shape, which has one or two degrees of freedom for the motion in the plane of the individual normals. The method was further improved by incorporating in a self-consistent way the requirement of minimum magnetic field variance along the magnetopause normal. An additional assumption, required in a previously proposed non-planar technique, i.e. that the non-planarity has negligible effects on the minimum variance analysis, is thus avoided. We applied the method to a magnetopause transition for which the various planar techniques provided inconsistent results. By contrast, the solutions obtained from the different implementations of the new 2-D method were consistent and stable, indicating a convex shape for the magnetopause. These solutions perform better than the planar solutions from the normal magnetic field variance perspective. The magnetopause dynamics and the presence of a non-zero normal magnetic field component in the analyzed event are discussed.
Magnetic guide field generation in collisionless current sheets
Authors: Baumjohann W. , Nakamura R. , Treumann R. A.
Published: June 2010

Abstract. In thin (Δ< few λi) collisionless current sheets in a space plasma like the magnetospheric tail or magnetopause current layer, magnetic fields can grow from thermal fluctuation level by the action of the non-magnetic Weibel instability (Weibel, 1959). The instability is driven by the counter-streaming electron inflow from the "ion diffusion" (ion inertial Hall) region into the inner current (electron inertial) region after thermalisation by the two-stream instability. Under magnetospheric tail conditions it takes ~50 e-folding times (~100 s) for the Weibel field to reach observable amplitudes |bW|~1 nT. In counter-streaming inflows these fields are of guide field type.
Daytime descending intermediate layers observed over a sub-tropical Indian station Waltair during low-solar activity period
Authors: Niranjan K. , Srivani B. , Naidu V. V. S.
Published: June 2010

Abstract. Study on daytime descending intermediate layer over subtropical Indian station Waltair (17.7° N, 83.3° E geographic, 6.4° N, 10° E geomagnetic, 20° N dip) located in the equatorial anomaly transition region, using an IPS 42 Digital Ionosonde during the low solar activity year 2004 showed that the layers occur in the altitude range of 140–160 km with maximum occurrence during winter solstice. The layers observed during daytime occur with a double peak variation throughout the year with less occurrence probability and shorter duration presence during forenoon hours. The morning layer descent was associated with a density increase where as during afternoon hours a decrease in density was observed. The downward drift velocity was about 8 km/h during morning hours and between 7–11 km/h during afternoon hours, with a low descent rate of around 4.5 km/h during summer morning hours. The results indicate the presence of a 6 h tide at this location as observed from the characteristics of the descending layers, unlike at majority of locations where a significant semi diurnal trend is observed. The study brings out the complex nature of the tidal interaction at different locations.
Comparison of the open-closed field line boundary location inferred using IMAGE-FUV SI12 images and EISCAT radar observations
Authors: Hubert B. , Aikio A. T. , Amm O. , Pitkänen T. , Kauristie K. , Milan S. E. , Cowley S. W. H. , Gérard J.-C.
Published: June 2010

Abstract. We compare the location of the polar cap boundary (PCB) determined using two different techniques, and use them as proxies for the open-closed field line boundary (OCB). Electron temperatures from observations of the EISCAT radar facility are used to estimate the latitude of the PCB along the meridian of the EISCAT VHF beam. The second method utilizes global images of proton aurora obtained by the IMAGE satellite FUV SI12 instrument. These methods are applied to three different intervals. In two events, the agreement between the methods is good and the mean of the difference is within the resolution of the observations. In a third event, the PCB estimated from EISCAT data is located several degrees poleward of that obtained from the IMAGE FUV SI12 instrument. Comparison of the reconnection electric field estimated from the two methods shows that high-resolution measurements both in time and space are needed to capture the variations in reconnection electric field during substorm expansion. In addition to the two techniques introduced above to determine the PCB location, we also use a search for the location of the reversal of the east-west component of the equivalent current known as the magnetic convection reversal boundary (MCRB). The MCRB from the MIRACLE magnetometer chain mainly follows the motion of the polar cap boundary during different substorm phases, but differences arise near the Harang discontinuity.
Global reconnection topology as inferred from plasma observations inside Kelvin-Helmholtz vortices
Authors: Bavassano Cattaneo M. B. , Marcucci M. F. , Bogdanova Y. V. , Rème H. , Dandouras I. , Kistler L. M. , Lucek E.
Published: June 2010

Abstract. During a long lasting period of northward interplanetary magnetic field and high solar wind speed (above 700 km/s), the Cluster spacecraft go across a number of very large rolled-up Kelvin-Helmholtz (KH) vortices at the dusk magnetopause, close to the terminator. The peculiarity of the present event is a particular sequence of ions and electrons distribution functions observed repeatedly inside each vortex. In particular, whenever Cluster crosses the current layer inside the vortices, multiple field-aligned ion populations appear, suggesting the occurrence of reconnection. In addition, the ion data display a clear velocity filter effect both at the leading and at the trailing edge of each vortex. This effect is not present in the simultaneous electron data. Unlike other KH studies reported in the literature in which reconnection occurs within the vortices, in the present event the observations are not compatible with local reconnection, but are accounted for by lobe reconnection occurring along an extended X-line at the terminator in the Southern Hemisphere. The reconnected field lines "sink" across the magnetopause and then convect tailward-duskward where they become embedded in the vortices. Another observational evidence is the detected presence of solar wind plasma on the magnetospheric side of the vortices, which confirms unambiguously the occurrence of mass transport across the magnetopause already reported in the literature. The proposed reconnection scenario accounts for all the observational aspects, regarding both the transport process and the kinetic signatures.
Oxygen ion energization observed at high altitudes
Authors: Waara M. , Nilsson H. , Stenberg G. , André M. , Gunell H. , Rème H.
Published: June 2010

Abstract. We present a case study of significant heating (up to 8 keV) perpendicular to the geomagnetic field of outflowing oxygen ions at high altitude (12 RE) above the polar cap. The shape of the distribution functions indicates that most of the heating occurs locally (within 0.2–0.4 RE in altitude). This is a clear example of local ion energization at much higher altitude than usually reported. In contrast to many events at lower altitudes, it is not likely that the locally observed wave fields can cause the observed ion energization. Also, it is not likely that the ions have drifted from some nearby energization region to the point of observation. This suggests that additional fundamentally different ion energization mechanisms are present at high altitudes. One possibility is that the magnetic moment of the ions is not conserved, resulting in slower outflow velocities and longer time for ion energization.
Results of Russian geomagnetic observatories in the 19th century: magnetic activity, 1841–1862
Authors: Nevanlinna H. , Häkkinen L.
Published: June 2010

Abstract. Hourly (spot readings) magnetic data (H- and D-components) were digitized from Russian yearbook tables for the years 1850–1862 from four observatories. The pdf pictures for digitization were taken by a normal digital camera. The database obtained consists of about 900 000 single data points. The time series of hourly magnetic values reveal slow secular variations (declination only) as well as transient and regular geomagnetic variations of external origin. The quality and homogeneity of the data is satisfactory. Daily Ak-indices were calculated using the index algorithm that has been earlier applied to 19th century data from Helsinki (Finland) as well as modern magnetic observatory recordings. The activity index series derived from the Russian data is consistent with earlier activity index series for 1850–1862. The digitized index data series derived in this study was extended back to 1841 by including magnetic C9 activity index data available from a Russian observatory (St. Petersburg). Magnetic data rescued here is well suitable for various reconstructions for studies of the long-term variation of the space weather in the 19th century.
Mesoscale convection system and occurrence of extreme low tropopause temperatures: observations over Asian summer monsoon region
Authors: Jain A. R. , Panwar V. , Mandal T. K. , Rao V. R. , Goel A. , Gautam R. , Das S. S. , Dhaka S. K.
Published: June 2010

Abstract. The present study examines the process of how tropospheric air enters the stratosphere, particularly in association with tropical mesoscale convective systems (TMCS) which are considered to be one of the causative mechanisms for the observation of extremely low tropopause temperature over the tropics. The association between the phenomena of convection and the observation of extreme low tropopause temperature events is, therefore, examined over the Asian monsoon region using data from multiple platforms. Satellite observations show that the area of low outgoing long wave radiation (OLR), which is a proxy for the enhanced convection, is embedded with high altitude clouds top temperatures (≤193 K). A detailed analysis of OLR and 100 hPa temperature shows that both are modulated by westward propagating Rossby waves with a period of ~15 days, indicating a close linkage between them. The process by which the tropospheric air enters the stratosphere may, in turn, be determined by how the areas of convection and low tropopause temperature (LTT) i.e. T≤191 K are spatially located. In this context, the relative spatial distribution of low OLR and LTT areas is examined. Though, the locations of low OLR and LTT are noticed in the same broad area, the two do not always overlap, except for partial overlap in some cases. When there are multiple low OLR areas, the LTT area generally appears in between the low OLR areas. Implications of these observations are also discussed. The present analysis also shows that the horizontal mean winds have a role in the spatial distribution of low OLR and LTT.
Low-frequency magnetic field fluctuations in Venus' solar wind interaction region: Venus Express observations
Authors: Guicking L. , Glassmeier K.-H. , Auster H.-U. , Delva M. , Motschmann U. , Narita Y. , Zhang T. L.
Published: June 2010

Abstract. We investigate wave properties of low-frequency magnetic field fluctuations in Venus' solar wind interaction region based on the measurements made on board the Venus Express spacecraft. The orbit geometry is very suitable to investigate the fluctuations in Venus' low-altitude magnetosheath and mid-magnetotail and provides an opportunity for a comparative study of low-frequency waves at Venus and Mars. The spatial distributions of the wave properties, in particular in the dayside and nightside magnetosheath as well as in the tail and mantle region, are similar to observations at Mars. As both planets do not have a global magnetic field, the interaction process of the solar wind with both planets is similar and leads to similar instabilities and wave structures. We focus on the spatial distribution of the wave intensity of the fluctuating magnetic field and detect an enhancement of the intensity in the dayside magnetosheath and a strong decrease towards the terminator. For a detailed investigation of the intensity distribution we adopt an analytical streamline model to describe the plasma flow around Venus. This allows displaying the evolution of the intensity along different streamlines. It is assumed that the waves are generated in the vicinity of the bow shock and are convected downstream with the turbulent magnetosheath flow. However, neither the different Mach numbers upstream and downstream of the bow shock, nor the variation of the cross sectional area and the flow velocity along the streamlines play probably an important role in order to explain the observed concentration of wave intensity in the dayside magnetosheath and the decay towards the nightside magnetosheath. But, the concept of freely evolving or decaying turbulence is in good qualitative agreement with the observations, as we observe a power law decay of the intensity along the streamlines. The observations support the assumption of wave convection through the magnetosheath, but reveal at the same time that wave sources may not only exist at the bow shock, but also in the magnetosheath.
Modelling solar cycle length based on Poincaré maps for Lorenz-type equations
Authors: Lundstedt H. , Persson T.
Published: June 2010

Abstract. Two systems of Lorenz-type equations modelling solar magnetic activity are studied: Firstly a low order dynamic system in which the toroidal and poloidal fields are represented by x- and y-coordinates respectively, and the hydrodynamical information is given by the z coordinate. Secondly a complex generalization of the three ordinary differential equations studied by Lorenz. By studying the Poincaré map we give numerical evidence that the flow has an attractor with fractal structure. The period is defined as the time needed for a point on a hyperplane to return to the hyperplane again. The periods are distributed in an interval. For large values of the Dynamo number there is a long tail toward long periods and other interesting comet-like features. These general relations found for periods can further be physically interpreted with improved helioseismic estimates of the parameters used by the dynamical systems. Solar Dynamic Observatory is expected to offer such improved measurements.
Selenium: Radionuclides
Authors: Shaw George , Ashworth Daniel
Published: June 2010

Selenium in the environment has been studied intensively for several decades, since it is both a trace nutrient and a toxin. It is a ubiquitous element in soils, waters, and the atmosphere, with chemical similarities to the other group 16 elements sulfur, polonium, and tellurium. Important selenium species in environmental media include inorganic oxyanions as well as organic species produced by biological methylation mechanisms. The only probable long‐term source of radioactive selenium to the environment is the leakage from radioactive waste repositories. Only79Se is of concern in this respect, since it is the only long‐lived radioactive isotope of selenium (physical half‐life = 377 000 years). Under alkaline geochemical conditions, there is the potential for79Se to migrate from geological radioactive waste repositories in very small quantities over very long periods. It is expected that any79Se released into the environment will behave in the same way as nonradioactive selenium, though the kinetics of isotopic exchange between79Se and stable selenium in soils, sediments, and other environmental media have never been studied over timescales relevant to radioactive waste disposal. It is unlikely that environmental concentrations of79Se will ever lead to exposures approaching the intake levels associated with stable selenium. Any exposure that does occur is likely to be primarily through the dietary intake pathway, since the principal environmental reservoirs, and therefore potential sources, of selenium in the environment are waters and soils.
Breakdown of Casimir invariance in curved space‐time
Authors: Singh D. , Mobed N.
Published: June 2010

It is shown that the commonly accepted definition for the Casimir scalar operators of the Poincaré group does not satisfy the properties of Casimir invariance when applied to the non‐inertial motion of particles while in the presence of external gravitational and electromagnetic fields, where general curvilinear co‐ordinates are used to describe the momentum generators within a Fermi normal co‐ordinate framework. Specific expressions of the Casimir scalar properties are presented. While the Casimir scalar for linear momentum remains Lorentz invariant in the absence of external fields, this is no longer true for the spin Casimir scalar. Potential implications are considered for the propagation of photons, gravitons, and gravitinos as described by the spin‐3/2 Rarita‐Schwinger vector‐spinor field. In particular, it is shown that non‐inertial motion introduces a frame‐based effective mass to the spin interaction, with interesting physical consequences that are explored in detail.
Die Aufklärung der Ribosomenstruktur (Nobel‐Aufsatz)
Authors: Ramakrishnan V.
Published: June 2010

Eine komplexe Struktur: Der Nobelpreis 2009 wurde für Untersuchungen der Struktur und Funktion des Ribosoms – der Proteinfabrik der Zelle – vergeben. Die Preisträger berichten hier aus erster Hand über die Entwicklungen auf diesem Gebiet, von den Anfänge ihrer Forschungen bis hin zum heutigen, detaillierten Wissensstand.
Morphology development and non‐isothermal crystallization behavior of polyamide 11/ethylene‐vinyl alcohol blends
Authors: Li Yingchun , Hu Guosheng , Wang Biaobing
Published: June 2010

High‐barrier polyamide 11 (PA11) was prepared by in situ co‐crosslinking technology using ethylene‐vinyl alcohol (EVOH) as the barrier layer, and the morphology development and non‐isothermal crystallization behavior were investigated. The scanning electron microscope (SEM) observations demonstrated that the morphology development was greatly dependent on the concentration of dicumyl peroxide (DCP). A pronounced lamellar morphology was obtained at 1.5% DCP loading level. The analysis of non‐isothermal crystallization kinetics indicated that the addition of EVOH and DCP affected the crystallization mode of PA 11. Notably, the crystallization rate of PA 11 was related with the morphology of EVOH and the interaction between EVOH and PA 11. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
A study on the cure characteristics of epoxy/diaminodiphenylmethane system prepared at room temperature
Authors: Ferdowsian Fatemeh , Ebrahimi Morteza , Jannesari Ali
Published: June 2010

The curing behavior and kinetics of epoxy resin with diaminodiphenylmethane (DDM) as the curing agent was studied by many researchers, however all of them prepared the system at a high‐temperature condition (i.e., T ≥ 80°C). In this study, a mixture of epoxy/DDM was prepared at ambient temperature and its curing characteristics were studied by using differential scanning calorimetry (DSC). The autocatalytic model was used to calculate the kinetic factors in the dynamic experiments. The kinetics of the curing reaction was also evaluated by two different isoconversional models; namely Friedman method and the Advanced Isoconversional method proposed by Vyazovkin to investigate the activation energy behavior during the curing reaction. The activation energy of the curing reaction was found to be in the range of 48 ± 2 kJ/mol and might be considered to be constant during the curing. In fact, our findings were different from the result reported by other researchers for the system which was prepared at elevated temperature. Therefore, it seems that the preparation temperature of the samples influenced considerably on the curing behavior of epoxy with DDM. Finally, a time–temperature–transformation (TTT) diagram was established to determine the cure process and glass transition properties of the system. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Influence of water and magnesium ion on the optical properties in various plasticized poly(vinyl butyral) sheets
Authors: Tupý Michael , Meřinská Dagmar , Svoboda Petr , Zvoníček Josef
Published: June 2010

The study is focused on influences of optical properties change of poly(vinyl butyral) (PVB) sheets determined for safety glass preparing. Optic measurements were evaluated itself and after, the laminated glass was observed. The study deals with a cognizance of causation of the optical properties change in different PVB sheets in dependence on adsorbed water content into the polymer matrix. Results of this work describe the influence of OH group content on PVB chain and type and amount of additives adjusting adhesion of PVB towards glass. However, the most important discovery of this work is evaluation of critical water content that leads to haze generation. The evaluation of various types of sheets was performed. At the same time the artificial addition of Mg2+ salts of organic acids (with various polarity of the molecule) was evaluated to assess their influence on haze generation. It was found that haze caused by Mg2+ salt is possible to eliminate when there is certain water content in PVB. Obtained values and comparisons are very important for PVB sheets industry and for industry dealing with lamination of PVB between glasses. Influence of these factors and comparison of haze generation for various PVB sheets has not been published yet. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Upgrading of acrylonitrile–butadiene copolymer properties using natural rubber–graft–N‐(4‐aminodiphenylether) acrylamide
Authors: Al‐Ghonamy Abdulaziz Ibrahim , Barakat Mirham A.
Published: June 2010

The grafting of ADPEA onto natural rubber was executed with UV radiation. Benzoyl peroxide was used to initiate the free‐radical grafting copolymerization. Natural rubber‐graft‐N‐(4‐aminodiphenylether) acrylamide (NR‐g‐ADPEA) was characterized with an IR technique. The ultrasonic velocities of both longitudinal and shear waves were measured in thermoplastic discs of NBR vulcanizates as a function of aging time. Ultrasonic velocity measurements were taken at 2 MHz ultrasonic frequency using the pulse echo method. We studied the effect of aging on the mechanical properties and the swelling and extraction phenomena for acrylonitrile–butadiene copolymer (NBR) vulcanizates, which contained the prepared NR‐g‐ADPEA and a commercial antioxidant, N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine. The prepared antioxidant enhanced both the mechanical properties of the NBR vulcanizates and the permanence of the ingredients in these vulcanizates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Studying the effects of SiO2 specifications and properties of (SiO2/MgCl2/TEOS/TiCl4/AlEt3) catalyst system on kinetic behavior and hydrogen responsibility of ethylene slurry polymerization
Authors: Vakili Mohammad , Arabi Hassan , Mobarakeh Hamid Salehi , Ghafelebashi Mehdi
Published: June 2010

A series of silica gels with different physico‐chemical properties such as average pore size diameter, pore volume, attrition quality index, and bulk density were prepared, characterized, and subjected to treatment in special thermal program. Catalyst precursors were prepared by reaction of these silica gels with dibutyl magnesium (MgBu2) at 50°C and then addition of tetraethoxy ortho silicate and subsequent impregnation with titanium tetrachloride (TiCl4). Polymerization of ethylene by these catalysts at comparable conditions and also at different PH2/PC2 ratio was carried out; the results showed that support properties have significant influence on polymerization behaviors such as activity profile, productivity, and hydrogen responsibility. To quantitative analysis of the results, a new kinetic relation for rate‐time profiles was derived, and these kinetic parameters were used to study and calculate of the effects of support specification. It was observed that trends of activity profiles were mainly affected by support properties and as well as PH2/PC2 ratio. Interestingly enough, catalysts with different pore volume diameter show different behavior with variation of PH2/PC2 ratio. Increasing in pore size diameter from 60 to 200 Å give raises catalyst activity by two times. Finally, mentioned variables were attributed to different particle growth and mechanism of fragmentation during polymerization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of silicon ester dispersants and its application in CaCO3/polyethylene composites
Authors: Ma Haihong , Liu Peizhen , Ren Fengmei , Zhou Zhengfa , Xu Weibing
Published: June 2010

Silicon ester dispersants were prepared using transesterification between ethyl petroleum silicate and the alkyl alcohols by different molecular masses. The dispersants were used to modify calcium carbonate (CaCO3), and their effect on the mechanical properties of CaCO3/polyethylene (PE) composites was investigated. The transesterification was confirmed by gas chromatography (GC). The optimal conditions for the preparation of silicon ester dispersants were 110°C for 3 h with 2% catalyst by weight and fixed molar ratio of isooctyl alcohol to ethyl petroleum silicate of 3 : 1. Fourier transmission infrared spectroscopy (FTIR) results indicated that the dispersants were coating to the CaCO3 particles. Dispersant with octadecanol as its solvable chain enabled the best modification effect. CaCO3/PE composites modified by dispersants demonstrated improved mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Photocatalytic Hydrogen Evolution by [FeFe] Hydrogenase Mimics in Homogeneous Solution
Authors: Wang Wen‐Guang , Wang Feng , Wang Hong‐Yan , Si Gang , Tung Chen‐Ho , Wu Li‐Zhu
Published: June 2010

To mimic [FeFe] hydrogenases (H2ases) in nature, molecular photocatalysts 1a, 1b, and 1c anchoring rhenium(I) complex S to one of the iron cores of [FeFe]‐H2ases model complex C, have been constructed for H2 generation by visible light in homogeneous solution. The time‐dependence of H2 evolution and a spectroscopic study demonstrate that the orientation of S and the specific bridge in 1a, 1b, and 1c are important both for the electron‐transfer step from the excited S* to the catalytic C, and the formation of unprecedented long‐lived charge separation for 1a (780 μs), 1b, and 1c (>2 ms) in [FeFe]‐H2ases mimics. The fast forward electron‐transfer step from the excited S* to the catalytic C but the slow back electron‐transfer step of the charge‐recombination in the designed photocatalysts 1a, 1b, and 1c are reminiscent of the behavior of [FeFe]‐H2ases in nature.
A risk‐averse user equilibrium model for route choice problem in signal‐controlled networks
Authors: Lam William H.K. , Chan K.S. , Li Zhi‐Chun , Bell Michael G.H.
Published: June 2010

This paper proposes a new risk‐averse user equilibrium (RAUE) model to estimate the distribution of traffic flows over road networks with taking account the effects of accident risks due to the conflicting traffic flows (left‐ and right‐turning and through traffic flows) at signalized intersections. It is assumed in the proposed model that drivers consider simultaneously both the travel time and accident risk in their route choices. The accident risk of a route is measured by the potential accident rate on that route. The RAUE conditions are formulated as an equivalent path‐based variational inequality problem which can be solved by a path‐based solution algorithm. It is shown that the traditional user equilibrium (UE) model is in fact a special case of the proposed model. A numerical example on a grid network is used to illustrate the application of the proposed model and to compare the results with the conventional UE traffic assignment. Numerical results show that the traditional UE model may underestimate the total system travel time and overestimate the system accident rate. Sensitivity tests are also carried out to assess the effects of drivers' preferences, signal control parameters (i.e., green time proportions), and various network demand levels on the route choice problem. Copyright © 2010 John Wiley & Sons, Ltd.
Messtechnische Analyse flachgeneigter hölzerner Dachkonstruktionen mit Sparrenvolldämmung — Teil 1: Nicht belüftete Nacktdächer mit Folienabdichtung
Authors: Nusser Bernd , Teibinger Martin , Bednar Thomas
Published: June 2010

Sehr hohe innenseitige Diffusionswiderstände für nichtbelüftete Dachaufbauten mit außenseitiger Folienabdichtung sind aufgrund der so geschaffenen Feuchtefallencharakteristik als kontraproduktiv anzusehen. Durch den Einsatz von feuchteadaptiven Dampfbremsen kann eine verstärkte diffusionsbedingte Rücktrocknung von Feuchtigkeit aus dem Gefach erreicht werden. Anhand von Freilanduntersuchungen werden fünf industriell gefertigte, flachgeneigte und leckagefreie hölzerne Nacktdächer mit Folienabdichtung, mit unterschiedlichen feuchteadaptiven Dampfbremsen und unterschiedlichen innenseitigen Beplankungen unter besonnten und vollzeitbeschatteten Randbedingungen messtechnisch analysiert. Dabei unterscheidet sich das hygrothermische Verhalten der verschiedenen Dachaufbauten während des 17‐monatigen Beobachtungszeitraums hauptsächlich aufgrund der unterschiedlichen Solareinstrahlung. In den besonnten Dachelementen zeigen sich auf der Gefachinnenseite deutlich kritischere Klimabedingungen als auf der Gefachaußenseite. Alle beschatteten Dachelemente weisen ein sehr negatives hygrisches Verhalten auf. Trotz hoher Feuchtelast im Innenraum und in den Gefachen ist in keinem der untersuchten Dachaufbauten zum Beobachtungsende ein biologischer Befall zu entdecken.

Measuring investigations of the hygrothermal behaviour of timber flat roofs — Part 1: Non‐ventilated compact roofs with waterproofing membranes. For compact roofs with roof waterproofing membranes very high inner diffusion resistances are counterproductive. This kind of construction has virtually no drying potential. By the use of smart vapour retarders a higher diffusion based drying rate can be achieved. Five industrial manufactured, full scale low pitched and leakage free timber flat roofs with roof waterproofing membranes, different smart vapour retarders and inner sheetings were investigated under sun‐exposed and fulltime shaded conditions. During the 17 months long investigation period the hygrothermal behaviour of the roofs differs mainly due to the different solar irradiation. In the exposed roofs the climates at the inner side of the cavity were clearly more critical as at the outer side of the cavity. All shaded roofs showed a very critical hygrothermal performance. Despite high moisture loads in the buildings and in the cavities no mould could be found in the inspected roofs.
Ist die Hinterlüftung von Holzfassaden ein Muss?
Authors: Kehl Daniel , Weber Heinz , Hauswirth Severin
Published: June 2010

Nach Durchführung einer großen Schweizer Forschungsinitiative zum Thema “Brandschutz im Holzbau” sind seit 2005 Außenwandbekleidungen aus Holz unter Zuhilfenahme von bestimmten Brandschutzmaßnahmen bis zur Hochhausgrenze (22 m) möglich [1]. Dazu zählen unter anderem auch Außenwandbekleidungen, deren Hinterlüftungsraum geschossweise unterbrochen und oben verschlossen wird. Solche Fassaden weisen brandschutztechnische Vorteile auf, da sie die Brandweiterleitung hinter der Bekleidung reduzieren bzw. verhindern. In diesem Zusammenhang stellte sich die Frage, ob eine Hinterlüftung von Holzfassaden aus bauphysikalischer Sicht überhaupt notwendig ist. Im Rahmen eines Forschungsvorhabens an der Berner Fachhochschule — Architektur, Holz und Bau in Biel/Bienne wurde dieser Frage nachgegangen [2].

Is ventilation of timber façades essential? Following a major Swiss research initiative, “Fire protection in Timber Structures”, exterior timber wall claddings incorporating specific fire protection measures have been permitted up to the high‐rise limit of 22 m since 2005 [1]. This includes exterior wall claddings with a ventilation space that is interrupted and closed off from above at each storey level. Such façades have advantages when it comes to fire protection as they reduce or prevent the spread of fire behind the cladding. This has raised the question of whether the ventilation of timber façades is necessary at all from a building physics perspective. This matter was investigated as part of an Architecture, Timber and Construction research project at Bern University of Applied Sciences [2].
Schwimmende Architektur: schwimmende Bauten als Aufgabenfeld für die Bauphysik
Authors: Stopp Horst , Strangfeld Peter , Giebler Stephan
Published: June 2010

Schwimmende Architektur, ein nicht eindeutiger Fachbegriff, wird zunehmend auch in Deutschland thematisiert. Punktuell entstehen exklusive Wohnbauten wie auch einfache schwimmende Ferienhäuser. Infolge spezifischer Randbedingungen auf dem Wasser sowohl für die Schwimmkörper als auch für deren Aufbauten ergeben sich zusätzliche Chancen und Risiken. Der Beitrag behandelt beispielhaft bauphysikalische Bezüge. Entwicklungstendenzen der Weltbevölkerung hinsichtlich Wachstum und Verteilung bei gleichzeitig steigendem Meeresspiegel erfordern künftig ein verstärktes wissenschaftliches Interesse und Engagement der Bauphysik auch für schwimmende Bauten.

Floating architecture and the responsibility of building physics for floating buildings. Floating architecture, a new and still unambiguous technical term is increasingly being addressed as subject in Germany. Point by popint exclusive buildings are constructed such as simple floating houses for holidays. As a result of specific boundary conditions of the water area for the pontoons as well as for their construction additional chances and risks are given. The paper represents examples with regard to the building physics. Development trends of the world population concerning growth and distribution coupled with rising sea levels call for an increased scientific interest and engagement of the building physics for floating architecture in future too.
Modell und Programm CLIMT zur einfachen Ermittlung der Raumlufttemperatur und Raumluftfeuchte bei freier Klimatisierung
Authors: Häupl Peter , Bishara Ayman , Hansel Frank
Published: June 2010

In der Planungspraxis besteht Bedarf nach einem vergleichsweise (siehe TRNSYS, ENERGY PLUS) einfachen und zuverlässigen Handwerkszeug zur Quantifizierung des Raumklimas. In diesem Beitrag wird ein praktikables Modell zur Ermittlung der Stundenwerte für die Raumlufttemperatur, die Empfindungstemperatur (Mitteltemperatur aus Raumluft‐ und Umschließungsflächentemperatur) und die Raumluftfeuchte in Abhängigkeit vom Außenklima (Außenlufttemperatur, Wärmestrahlung und relative Luftfeuchtigkeit der Außenluft), von den Gebäudeparametern (Geometrie, Wärmetransportwiderstände der Hüllkonstruktion, Wärme‐ und Feuchteabsorptionsvermögen der Bauteile), von der Lüftung und der Raumnutzung (innere Wärmequellen, innere Feuchtequellen und raumluftregulierte Heizung) bei freier Klimatisierung vorgestellt. Die Ergebnisse bilden den Quelltext für das nutzerfreundliche Windows‐Programm CLIMT (CLimate‐Indoor‐Moisture‐Temperature). Modell und Programm CLIMT werden durch einen Vergleich mit Rechenwerten nach TRNSYS und Messwerten in einem Testhaus validiert. Die Ergebnisse stimmen sehr gut überein. Das Programm CLIMT ist anwenderfreundlich und praxistauglich.

Model and program CLIMT for a simplified determination of room temperature and relative humidity under arbitrary climate conditions. In planning practice there is a need for a comparably simple (cf. TRNSYS, ENERGY PLUS), reliable tool for quantifying an indoor climate. In this article a practicable model is put forward for determining the hourly values for natural conditioning of indoor air temperature, the perceived temperature (average of air and enclosing surface temperatures) and the interior air humidity in relation to the external climate (external air temperature, radiant heat and relative humidity of the outside air), the building parameters (geometry, heat transfer resistance of the shell structure, heat and moisture absorption properties of the components), the ventilation and the use of the space (interior heat sources, interior moisture sources and interior air‐regulated heating). The results form the source text for the user‐friendly Windows program CLIMT (CLimate‐Indoor‐Moisture‐Temperature). The CLIMT model and program are validated in a test house by comparing values calculated using TRNSYS with measured values. The results agree very well. The CLIMT program is user‐friendly and practically‐oriented.
Intracellular antibodies and cancer: New technologies offer therapeutic opportunities
Authors: Pérez‐Martínez David , Tanaka Tomoyuki , Rabbitts Terence H.
Published: June 2010

Since the realisation that the antigen‐binding regions of antibodies, the variable (V) regions, can be uncoupled from the rest of the molecule to create fragments that recognise and abrogate particular protein functions in cells, the use of antibody fragments inside cells has become an important tool in bioscience. Diverse libraries of antibody fragments plus in vivo screening can be used to isolate single chain variable fragments comprising VH and VL segments or single V‐region domains. Some of these are interfering antibody fragments that compete with protein‐protein interactions, providing lead molecules for drug interactions that until now have been considered difficult or undruggable. It may be possible to deliver or express antibody fragments in target cells as macrodrugs per se. In future incarnations of intracellular antibodies, however, the structural information of the interaction interface of target and antibody fragment should facilitate development of binding site mimics as small drug‐like molecules. This is a new dawn for intracellular antibody fragments both as macrodrugs and as precursors of drugs to treat human diseases and should finally lead to the removal of the epithet of the ‘undruggable’ protein‐protein interactions.
Simple Biosensor with High Selectivity and Sensitivity: Thiol‐Specific Biomolecular Probing and Intracellular Imaging by AIE Fluorogen on a TLC Plate through a Thiol–Ene Click Mechanism
Authors: Liu Yang , Yu Yong , Lam Jacky W. Y. , Hong Yuning , Faisal Mahtab , Yuan Wang Zhang , Tang Ben Zhong
Published: June 2010

A handy, specific, sensitive bioprobe has been developed. Tetraphenylethene (TPE) was functionalized by a maleimide (MI) group, giving a TPE‐MI adduct that was nonemissive in both solution and the solid state. It was readily transformed into a fluorogen showing an aggregation‐induced emission (AIE) property by the click addition of thiol to its MI pendant. The click reaction and the AIE effect enabled TPE‐MI to function as a thiol‐specific bioprobe in the solid state. Thus, the spot of TPE‐MI on a TLC plate became emissive when it had been exposed to L‐cysteine, an amino acid containing a thiol group, but remained nonemissive when exposed to other amino acids that lack free thiol units. The thiol‐activated emission was rapid and strong, readily detected by the naked eye at an analyte concentration as low as approximately 1 ppb, thanks to the “lighting up” nature of the bioprobing process. Similarly, the emission of TPE‐MI was turned on only by the proteins containing free thiol units, such as glutathione. Clear fluorescence images were taken when living cells were stained by using TPE‐MI as a visualization agent, affording a facile fluorescent maker for mapping the distribution of thiol species in cellular systems.
Phosphine–Alkene Ligands as Mechanistic Probes in the Pauson–Khand Reaction
Authors: Ferrer Catalina , Benet‐Buchholz Jordi , Riera Antoni , Verdaguer Xavier
Published: June 2010

An alkyne tetracarbonyl dicobalt complex with a chelated phosphine–alkene ligand, in which the phosphorus atom and the alkene from the ligand are attached to the same cobalt atom has been prepared, isolated, and characterized by X‐ray crystallography. The complex serves as a mechanistic model for an intermediate of the Pauson–Khand (PK) reaction. Although the alkene fragment is located in an equatorial coordination site with an appropriate orientation, and, therefore, should undergo insertion, it failed to give the PK product upon either thermal or N‐methylmorpholine N‐oxide activation. However, a phosphine–alkene complex that contains a terminal alkene readily provided the corresponding PK product. We attribute this change in reactivity to the different ability of each olefin to undergo 1,2‐insertion. These results provide further insights into the factors that govern a crucial step in the PK reaction, the olefin insertion.
3D–2D–0D Stepwise Deconstruction of a Water Framework Templated by a Nanoporous Organic–Inorganic Hybrid Host
Authors: Rocha João , Shi Fa‐Nian , Paz Filipe A. Almeida , Mafra Luís , Sardo Mariana , Cunha‐Silva Luís , Chisholm James , Ribeiro‐Claro Paulo , Trindade Tito
Published: June 2010

The supramolecular salt [H2pip]3[Ge(hedp)2]⋅14 H2O (1) [H2pip2+=piperazine cation C4H12N22+; hedp5−=deprotonated form of etidronic acid, C2H3P2O75−) is reported. This consists of an organic–inorganic hybrid hydrogen‐bonded nanoporous framework, the internal surface of which acts as a template for the three‐dimensional (3D) clustering of water molecules. The structure and molecular dynamics of this material are characterised by single‐crystal X‐ray diffraction, thermogravimetric analysis, Raman (H/D isotopic substitution) spectroscopy, and 2H solid‐state (wide‐line and MAS) NMR spectroscopy. Material 1 is shown to be unusual because 1) few nanoporous materials exhibit a well‐organised 3D framework of water molecules, 2) it provides a unique opportunity to follow experimentally and to rationalise the deconstruction of a 3D water framework and 3) despite the fact that the hybrid framework is a supramolecular salt, the structure does not collapse after dehydration and the final material is crystalline.
Simple Synthesis of Ruthenium π Complexes of Aromatic Amino Acids and Small Peptides
Authors: Perekalin Dmitry S. , Karslyan Eduard E. , Petrovskii Pavel V. , Nelyubina Yulia V. , Lyssenko Konstantin A. , Kononikhin Alexey S. , Nikolaev Eugene N. , Kudinov Alexander R.
Published: June 2010

The interaction of [Ru(η6‐C10H8)(Cp)]+ (Cp=C5H5) with aromatic amino acids (L‐phenylalanine, L‐tyrosine, L‐tryptophane, D‐phenylglycine, and L‐threo‐3‐phenylserine) under visible‐light irradiation gives the corresponding [Ru(η6‐amino acid)(Cp)]+ complexes in near‐quantitative yield. The reaction proceeds in air at room temperature in water and tolerates the presence of non‐aromatic amino acids (except those which are sulfur containing), monosaccharides, and nucleotides. The complex [Ru(η6‐C10H8)(Cp)]+ was also used for selective labeling of Tyr and Phe residues of small peptides, namely, angiotensin I and II derivatives.
ChemInform Abstract: Antiaromatic Triplet Ground State Molecules: Building Blocks for Organic Magnets
Authors: Breslow Ronald
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: The Electronic Structure of Some Mono‐ and Bisoxazolines.
Authors: Kovac Branka , Klasinc Leo , Raza Zlata , Sunjic Vitomir
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Sequential Nitromethane Conjugate Addition/Elimination—Pd‐Catalyzed Allylation of β‐Trifloxy Acrylates. Application to Carbapenem Synthesis.
Authors: Chung John Y. L. , Grabowski Edward J. J. , Reider Paul J.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Kinetics and Mechanism of Heterogeneous Palladium‐Catalyzed Coupling Reactions of Chloroaryls in Water.
Authors: Mukhopadhyay Sudip , Rothenberg Gadi , Gitis Diana , Wiener Harold , Sasson Yoel
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.