bluuebunny/crossref_metadata_2025 huggingface dataset:
Hausdorff–Young Inequalities for Group Extensions
Authors: Führ Hartmut
Published: December 2010

This paper studies Hausdorff–Young inequalities for certain group extensions, by use of Mackey's theory. We consider the case in which the dual action of the quotient group is free almost everywhere. This result applies in particular to yield a Hausdorff–Young inequality for nonunimodular groups.
On Valuations, Places and Graded Rings Associated to ∗-Orderings
Authors: Klep Igor
Published: December 2010

We study natural ∗-valuations, ∗-places and graded ∗-rings associated with ∗-ordered rings. We prove that the natural ∗-valuation is always quasi-Ore and is even quasi-commutative (i.e., the corresponding graded ∗-ring is commutative), provided the ring contains an imaginary unit. Furthermore, it is proved that the graded ∗-ring is isomorphic to a twisted semigroup algebra. Our results are applied to answer a question of Cimprič regarding ∗-orderability of quantum groups.
φ-Dialgebras and a Class of Matrix “Coquecigrues”
Authors: Ongay Fausto
Published: December 2010

Starting with the Leibniz algebra defined by a φ-dialgebra, we construct examples of “coquecigrues,” in the sense of Loday, that is to say, manifolds whose tangent structure at a distinguished point coincides with that of the Leibniz algebra. We discuss some possible implications and generalizations of this construction.
On Quotients of Non-Archimedean Köthe Spaces
Authors: Śliwa Wiesław
Published: December 2010

We show that there exists a non-archimedean Fréchet-Montel spaceWwith a basis and with a continuous norm such that any non-archimedean Fréchet space of countable type is isomorphic to a quotient ofW. We also prove that any non-archimedean nuclear Fréchet space is isomorphic to a quotient of some non-archimedean nuclear Fréchet space with a basis and with a continuous norm.
Every Real Algebraic Integer Is a Difference of Two Mahler Measures
Authors: Drungilas Paulius , Dubickas Artūras
Published: December 2010

We prove that every real algebraic integer α is expressible by a difference of two Mahler measures of integer polynomials. Moreover, these polynomials can be chosen in such a way that they both have the same degree as that of α, say d, one of these two polynomials is irreducible and another has an irreducible factor of degree d, so that α = M(P)−bM(Q) with irreducible polynomials P,Q ∈ ℤ[X] of degree d and a positive integer b. Finally, if d ⩽ 3, then one can take b = 1.
Beurling's Theorem and Characterization of Heat Kernel for Riemannian Symmetric Spaces of Noncompact Type
Authors: Sarkar Rudra P. , Sengupta Jyoti
Published: December 2010

We prove Beurling's theorem for rank 1 Riemannian symmetric spaces and relate its consequences with the characterization of the heat kernel of the symmetric space.
Determination of Hauptmoduls and Construction of Abelian Extensions of Quadratic Number Fields
Authors: Chiang-Hsieh Hung-Jen , Yang Yifan
Published: December 2010

We obtain Hauptmoduls of genus zero congruence subgroups of the type (p) := Γ0(p) + wp, where p is a prime and wp is the Atkin–Lehner involution. We then use the Hauptmoduls, along with modular functions on Γ1(p) to construct families of cyclic extensions of quadratic number fields. Further examples of cyclic extension of bi-quadratic and tri-quadratic number fields are also given.
Real Hypersurfaces in Complex Projective Space Whose Structure Jacobi Operator Is of Codazzi Type
Authors: Pérez Juan de Dios , Santos Florentino G. , Suh Young Jin
Published: December 2010

We prove the non existence of real hypersurfaces in complex projective space whose structure Jacobi operator is of Codazzi type.
Equivariant Cohomology of S1-Actions on 4-Manifolds
Authors: Godinho Leonor
Published: December 2010

Let M be a symplectic 4-dimensional manifold equipped with a Hamiltonian circle action with isolated fixed points. We describe a method for computing its integral equivariant cohomology in terms of fixed point data. We give some examples of these computations.
On the Image of Certain Extension Maps. I
Authors: Mejía Israel Moreno
Published: December 2010

Let X be a smooth complex projective curve of genus g ≥ 1. Let ξ ∈ J1(X) be a line bundle on X of degree 1. LetW = Ext1(ξn, ξ–1) be the space of extensions of ξn by ξ–1. There is a rational map Dξ : G(n,W) → SUX(n + 1), where G(n,W) is the Grassmannian variety of n-linear subspaces of W and SUX(n + 1) is the moduli space of rank n + 1 semi-stable vector bundles on X with trivial determinant. We prove that if n = 2, then Dξ is everywhere defined and is injective.
MKZ Type Operators Providing a Better Estimation on [1/2, 1)
Authors: Özarslan M. Ali , Duman Oktay
Published: December 2010

In the present paper, we introduce a modification of the Meyer-König and Zeller (MKZ) operators which preserve the test functions f0(x) = 1 and f2(x) = x2, and we show that this modification provides a better estimation than the classical MKZ operators on the interval [½, 1) with respect to the modulus of continuity and the Lipschitz class functionals. Furthermore, we present the r-th order generalization of our operators and study their approximation properties.
Weak Semiprojectivity for Purely InfiniteC*-Algebras
Authors: Spielberg Jack
Published: December 2010

We prove that a separable, nuclear, purely infinite, simpleC*-algebra satisfying the universal coefficient theorem is weakly semiprojective if and only if itsK-groups are direct sums of cyclic groups.
On Willmore's Inequality for Submanifolds
Authors: Zhou Jiazu
Published: December 2010

Let M be an m dimensional submanifold in the Euclidean space Rn and H be the mean curvature ofM. We obtain some low geometric estimates of the total squaremean curvature ∫M H2dσ. The low bounds are geometric invariants involving the volume of M, the total scalar curvature of M, the Euler characteristic and the circumscribed ball of M.
On Axiomatizability of Non-Commutative Lp-Spaces
Authors: Henson C. Ward , Raynaud Yves , Rizzo Andrew
Published: December 2010

It is shown that Schatten p-classes of operators between Hilbert spaces of different (infinite) dimensions have ultrapowers which are (completely) isometric to non-commutative Lp-spaces. On the other hand, these Schatten classes are not themselves isomorphic to non-commutative Lp spaces. As a consequence, the class of non-commutative Lp-spaces is not axiomatizable in the first-order language developed by Henson and Iovino for normed space structures, neither in the signature of Banach spaces, nor in that of operator spaces. Other examples of the same phenomenon are presented that belong to the class of corners of non-commutative Lp-spaces. For p = 1 this last class, which is the same as the class of preduals of ternary rings of operators, is itself axiomatizable in the signature of operator spaces.
p-Radial Exceptional Sets and Conformal Mappings
Authors: Kot Piotr
Published: December 2010

For p > 0 and for a given set E of type Gδ in the boundary of the unit disc ∂ we construct a holomorphic function f ∈ such that

In particular if a set E has a measure equal to zero, then a function f is constructed as integrable with power p on the unit disc .
Ramification des groupes abéliens d’automorphismes des corps
Authors: Laubie François
Published: December 2010

Soit q une puissance d’un nombre premier p. Dans cette note on établit la généralisation suivante d’un théorème de Wintenberger : tout sous-groupe abélien fermé du groupe des -automorphismes continus du corps des séries formelles muni de sa filtration de ramification est un groupe filtré isomorphe au groupe de Galois d’une extension abélienne d’un corps local à corps résiduel , filtré par les groupes de ramification de l’extension en numérotation inférieure.
Smoke injection heights from agricultural burning in Eastern Europe as seen by CALIPSO
Authors: Amiridis V. , Giannakaki E. , Balis D. S. , Gerasopoulos E. , Pytharoulis I. , Zanis P. , Kazadzis S. , Melas D. , Zerefos C.
Published: December 2010

Abstract. High frequency of agricultural fires is observed every year during the summer months over SW Russia and Eastern Europe. This study investigates the initial injection height of aerosol generated by the fires over these regions during the biomass burning season, which determines the potential for long-range transport of the smoke. This information is critical for aerosol transport modeling, as it determines the smoke plume evolution. The study focuses on the period 2006–2008, and is based on observations made by the CALIOP instrument on board the NASA CALIPSO satellite. MODIS data are synergistically used for the detection of the fires and the characterization of their intensity. CALIPSO aerosol vertical distributions generated by the active fires are analyzed to investigate the aerosol top height which is considered dependent on the heat generated by the fires and can be associated with the initial injection height. Aerosol top heights of the vertically homogenous smoke layers are found to range between 1.6 and 5.9 km. Smoke injection heights from CALIPSO are compared with mixing layer heights taken by the European Centre for Medium-range Weather Forecast (ECMWF), to investigate the direct injection of smoke particles into the free troposphere. Our results indicate that the aerosol plumes are observed within the boundary layer for the 50% of the cases examined. For the rest of the cases, the strong updrafts generated by the fires resulted to smoke injection heights greater than the ECMWF estimated mixing layer by 0.5 to 3.0 km, indicating a direct smoke injection into the free troposphere. The smoke injection height showed a dependence on the MODIS-Land Fire Radiative Power product which is indicative of the fire intensity, especially in the cases of lower static stability in the upper part of the boundary layer and the free troposphere.
On the water thermal response to the passage of cold fronts: initial results for Itumbiara reservoir (Brazil)
Authors: Alcântara E. H. , Bonnet M. P. , Assireu A. T. , Stech J. L. , Novo E. M. L. M. , Lorenzzetti J. A.
Published: December 2010

Abstract. The passage of meteorological systems such as cold fronts or convergence zones over reservoirs can cause significant modifications in several aquatic variables. Cold fronts coming from higher latitudes and reaching the Southeastern Brazilian territory modify the mean wind field and have important impact over physical, chemical and biological processes that act in the hydroelectric reservoirs. The mean period of cold front passages along the Southeastern Brazilian coast is 6 days during the winter and between 11 and 14 days in the summer. Most of these fronts also affect the hinterland of São Paulo, Minas Gerais and Goiás states. The objective of this work is to analyze the influence of cold front passages in the thermal stratification and water quality of the Itumbiara hydroelectric reservoir which is located in Minas Gerais and Goiás. The characterization of cold front passages over the study area was done through the analysis of GOES satellite images. The analyzed data set includes time series of meteorological (wind direction and intensity, short-wave radiation, air temperature, relative humidity, atmospheric pressure) and water temperature in four depths (5, 12, 20 and 40 m). The data set was acquired in the interior of the reservoir by an autonomous anchored buoy system at a sampling rate of 1 h. The stratification was assessed by non-dimensional parameter analysis. The lake number an indicator of the degree of stability and mixing in the reservoir was used in this analysis. We will show that during the cold front all atmospheric parameters respond and this response are transferred immediately to the water surface. The main effect is observed in the water column, when the heat loss in the surface allows the upwelling events caused by convective cooling due to the erosion of thermal stratification.
Experimental study on the rheological behaviour of debris flow
Authors: Scotto di Santolo A. , Pellegrino A. M. , Evangelista A.
Published: December 2010

Abstract. A model able to describe all the processes involved in a debris flow can be very complex owing to the sudden changing of the material that turns from solid into liquid state. The two phases of the phenomenon are analysed separately referring to soil mechanics procedures with regard to the trigger phase, and to an equivalent fluid for the post-failure phase. The present paper is devoted to show the experimental results carried out to evaluate the behaviour assumed by a pyroclastic-derived soil during the flow. A traditional fluid tool has been utilized: a standard rotational rheometer equipped with two different geometries. The soils tested belong to deposits that cover the slopes of the Campania region, Italy, often affected by debris flows. The influence of solid concentration Cv and grain size distribution was tested: the soils were destructurated, sieved and mixed with water starting from the in situ porosity. All material mixtures showed a non-Newtonian fluid behaviour with a yield stress τy that increases with a solid volumetric concentration and decreases for an increase of sand fraction. The experimental data were fitted with standard model for fluids. A simple relation between Cv and τy was obtained. The yield stress seems to be a key parameter for describing and predicting the post-failure behaviour of debris flows. These results suggest that in the field a small change in solid fraction, due to rainfall, will cause a slight decrease of the static yield stress, readily inducing a rapid flow which will stop only when the dynamic yield stress is reached, namely on a much smoother slope. This can explain the in situ observed post-failure behaviour of debris flows, which are able to flow over very long distances even on smooth slopes.
Measuring the effect of fuel treatments on forest carbon using landscape risk analysis
Authors: Ager A. A. , Finney M. A. , McMahan A. , Cathcart J.
Published: December 2010

Abstract. Wildfire simulation modelling was used to examine whether fuel reduction treatments can potentially reduce future wildfire emissions and provide carbon benefits. In contrast to previous reports, the current study modelled landscape scale effects of fuel treatments on fire spread and intensity, and used a probabilistic framework to quantify wildfire effects on carbon pools to account for stochastic wildfire occurrence. The study area was a 68 474 ha watershed located on the Fremont-Winema National Forest in southeastern Oregon, USA. Fuel reduction treatments were simulated on 10% of the watershed (19% of federal forestland). We simulated 30 000 wildfires with random ignition locations under both treated and untreated landscapes to estimate the change in burn probability by flame length class resulting from the treatments. Carbon loss functions were then calculated with the Forest Vegetation Simulator for each stand in the study area to quantify change in carbon as a function of flame length. We then calculated the expected change in carbon from a random ignition and wildfire as the sum of the product of the carbon loss and the burn probabilities by flame length class. The expected carbon difference between the non-treatment and treatment scenarios was then calculated to quantify the effect of fuel treatments. Overall, the results show that the carbon loss from implementing fuel reduction treatments exceeded the expected carbon benefit associated with lowered burn probabilities and reduced fire severity on the treated landscape. Thus, fuel management activities resulted in an expected net loss of carbon immediately after treatment. However, the findings represent a point in time estimate (wildfire immediately after treatments), and a temporal analysis with a probabilistic framework used here is needed to model carbon dynamics over the life cycle of the fuel treatments. Of particular importance is the long-term balance between emissions from the decay of dead trees killed by fire and carbon sequestration by forest regeneration following wildfire.
Nanotechnology‐Enabled Closed Loop Insulin Delivery Device: In Vitro and In Vivo Evaluation of Glucose‐Regulated Insulin Release for Diabetes Control
Authors: Gordijo Claudia R. , Koulajian Khajag , Shuhendler Adam J. , Bonifacio Leonardo D. , Huang Hui Yu , Chiang Simon , Ozin Geoffrey A. , Giacca Adria , Wu Xiao Yu
Published: December 2010

Recently, a new multifunctional, bio‐inorganic nanocomposite membrane with the ability to self‐regulate the release of insulin in response to blood glucose (BG) levels was reported. Herein, the application of this material as part of a small, implantable, closed‐loop insulin delivery device designed to continuously monitor BG concentrations and regulate insulin release is proposed. The insulin delivery device consists of a nanocomposite glucose‐responsive plug covalently bound to an insulin reservoir made of surface‐modified silicone. The plug is prepared with crosslinked bovine serum albumin (BSA) and enzymes (glucose oxidase (GOx) and catalase (CAT)), pH‐responsive hydrogel nanoparticles, and multifunctional MnO2 nanoparticles. The plug functions both as a glucose sensor and controlled delivery unit to release higher rates of insulin from the reservoir in response to hyperglycemic BG levels and basal insulin rates at normal BG concentration. The surfaces of the device are modified by silanization followed by PEGylation to ensure its safety and biocompatibility and the stability of encased insulin. Our results show that insulin release can be modulated in vitro in response to glucose concentrations. In vivo experiments show that the glycemia of diabetic rats can be controlled with implantation of the prototype device. The glucose‐responsiveness of the device is also demonstrated by rapid drop in BG level after challenging diabetic rats with bolus injection of glucose solution. In addition, it is demonstrated that surface PEGylation of the device is necessary for reducing the immune response of the host to the implanted foreign object and maintaining insulin stability and bioactivity. With this molecular architecture and the bio‐inorganic nanocomposite plug, the device has the ability to maintain normal BG levels in diabetic rats.
Regio‐ and Stereoselective Biohydroxylations with a Recombinant Escherichia coli Expressing P450pyr Monooxygenase of Sphingomonas Sp. HXN‐200
Authors: Zhang Wei , Tang Weng Lin , Wang Zunsheng , Li Zhi
Published: December 2010

A recombinant Escherichia coli expressing P450pyr monooxygenase of Sphingomonas sp. HXN‐200 was developed as a useful biocatalyst for regio‐ and stereoselective hydroxylations, with no side reaction and easy cell growth. The resting E. coli cells showed an activity of 4.1 U/g cdw and 9.9 U/g cdw for the hydroxylation of N‐benzylpyrrolidin‐2‐one 1 and N‐benzyloxycarbonylpyrrolidine 3, respectively, being as active as the wide‐type strain. Biohydroxylation of N‐benzylpyrrolidin‐2‐one 1 with the resting cells gave (S)‐N‐benzyl‐4‐hydroxypyrrolidin‐2‐one 2 in >99% ee and 10.8 mM, a 2.6 times increase of product concentration in comparison with the wild‐type strain. Biohydroxylation of N‐tert‐butoxycarbonylpiperidin‐2‐one 5, N‐benzylpiperidine 7 and N‐tert‐butoxycarbonylazetidine 9 with the E. coli cells afforded the corresponding 4‐hydroxypiperidin‐2‐one 6, 4‐hydroxypiperidine 8, and 3‐hydroxyazetidine 10 in 14 mM, 17 mM, and 21 mM, respectively. Moreover, hydroxylation of (−)‐β‐pinene 11 with the recombinant E. coli cells showed excellent regio‐ and stereoselectivity and gave (1R)‐trans‐pinocarveol 12 in 82% yield and 4.1 mM, which is over 200 times higher than that obtained with the best biocatalytic system known thus far. The recombinant strain was also able to hydroxylate other types of substrates with unique selectivity: biohydroxylation of norbornane 13 gave exo‐norbornaeol 14, with exo/endo selectivity of 95%; tetralin 15 and 6‐methoxytetralin 17 were hydroxylated at the non‐activated 2‐position, for the first time, with regioselectivities of 83–84%.
Highly Active and Enantioselective Rhodium‐Catalyzed Asymmetric 1,4‐Addition of Arylboronic Acid to α,β‐ Unsaturated Ketone by using Electron‐Poor MeO‐F12‐BIPHEP
Authors: Korenaga Toshinobu , Maenishi Ryota , Hayashi Keigo , Sakai Takashi
Published: December 2010

The asymmetric 1,4‐addition of phenylboronic acid to cyclohexenone were performed by using a low amount of rhodium/(R)‐(6,6′‐dimethoxybiphenyl‐2,2′‐diyl)bis[bis(3,4,5‐trifluorophenyl)phosphine] (MeO‐F12‐BIPHEP) catalyst. Because the catalyst shows thermal resistance at 100 °C, up to 0.00025 mol% Rh catalyst showed good catalytic activity. The highest turnover frequency (TOF) and turnover number (TON) observed were 53,000 h−1 and 320,000, respectively. The enantioselectivities of the products were maintained at a high level of 98% ee in these reactions. The Eyring plots gave the following kinetic parameters (ΔΔH≠=−4.0±0.1 kcal mol−1 and ΔΔS≠=−1.3±0.3 cal mol−1 K−1), indicating that the entropy contribution is relatively small. Both the result and consideration of the transition state in the insertion step at the B3LYP/6‐31G(d) [LANL2DZ for rhodium] levels indicated that the less σ‐donating electron‐poor (R)‐MeO‐F12‐BIPHEP could be creating a rigid chiral environment around the rhodium catalyst even at high temperature.
Non‐Magnetic and Magnetic Supported Copper(I) Chelating Adsorbents as Efficient Heterogeneous Catalysts and Copper Scavengers for Click Chemistry
Authors: Megia‐Fernandez Alicia , Ortega‐Muñoz Mariano , Lopez‐Jaramillo Javier , Hernandez‐Mateo Fernando , Santoyo‐Gonzalez Francisco
Published: December 2010

Novel supported chelating adsorbents bearing diverse multidentate nitrogenated ligands with strong copper(I) affinities are easily prepared in non‐magnetic and magnetic variants using silica and silica‐coated magnetite nanoparticles as suitable supports and the aza‐Michael‐type addition of vinyl sulfones as the ligation tool. These adsorbents are versatile materials with applications in the copper‐catalyzed alkyne‐azide cycloaddition (CuAAC) click chemistry where their complexation abilities enable them to act either as heterogeneous click catalysts when used in their complexed form or as copper(I) scavengers when used in their uncomplexed form. In the first instance, they proved to be robust and efficient heterogeneous catalysts to promote click reactions using extremely low doses and showing negligible copper leaching, particularly in the case of the silica‐based non‐magnetic adsorbents, allowing a simple operational protocol for their rapid and easy removal by filtration or magnetic decantation and showing good recyclability properties. In their uncomplexed form, the non‐magnetic chelating adsorbents are very efficient copper scavengers that are able to remove any traces of metal contamination and that can be applied in tandem with any heterogeneous supported copper(I) catalysts or as stand‐alone copper removing system in any click protocol allowing the isolation of metal‐free clicked compounds.
Study on the Reactivity of Aldehydes in Electrolyzed Ionic Liquids: Benzoin Condensation – Volatile Organic Compounds (VOCs) vs. Room Temperature Ionic Liquids (RTILs)
Authors: Chiarotto I. , Feroci M. , Orsini M. , Feeney M. M. M. , Inesi A.
Published: December 2010

The benzoin condensation of aromatic and heteroaromatic aldehydes, catalyzed by electrochemically generated N‐heterocyclic carbenes, has been set up in the absence of organic solvents and bases. α‐Hydroxy ketones have been isolated in good to elevated yields, in short reaction times. Aldol products and carbene‐aldehyde adducts have been obtained in elevated yields from linear and short branched aldehydes, respectively. A comparison with the use of classical organic solvents has been reported
Retro‐Diels–Alder Reactions of Masked Cyclopentadienones Catalyzed by Heterogeneous Brønsted Acids
Authors: Demuynck Anneleen L. W. , Levecque Pieter , Kidane Aklilu , Gammon David W. , Sickle Eugene , Jacobs Pierre A. , De Vos Dirk E. , Sels Bert F.
Published: December 2010

The zeolite H‐Beta catalyzes the retro‐Diels–Alder reaction of a range of cyclopentadiene cyclo‐adducts at moderate temperatures and ambient pressure, in the presence of an active dienophile. The active catalyst was identified and optimum reaction conditions established after screening a range of zeolites in the retro‐Diels–Alder reaction of the cyclopentadiene adduct of cyclopentenone. Our results suggest that retro‐Diels–Alder reactions of tricyclodecadienones are catalyzed by Brønsted acids and the high catalytic performance of H‐Beta catalysts can be ascribed to the optimal balance between the number of acid sites and their strength as well as to the accessibility of these sites. The methodology was then applied to a series of alkyl derivatives of cyclopentadienylcyclopentenones to provide a viable alternative synthetic route to 4‐alkylcyclopentenones and the versatility of the approach was demonstrated by the successful cycloreversion of N‐cyclohexyl‐2‐azanorborn‐5‐ene.
Readily Accessible Oxazolidine Nitroxyl Radicals: Bifunctional Cocatalysts for Simplified Copper Based Aerobic Oxidation
Authors: Gartshore Christopher J. , Lupton David W.
Published: December 2010

Using a two‐step procedure a range of bifunctional oxazolidine nitroxyl radicals have been prepared. The application of these co‐catalysts to the copper‐based aerobic oxidation of alcohols was then investigated. From these studies it was found that the parent tetramethyloxazolidine nitroxyl radical L1 was competent for oxidation in the presence of 2,2′‐bipyridine, and the bifunctional pyridyl‐containing nitroxyl radicals L2 and L3 could be used in the absence of additional coordinating ligands. Following optimization, the scope of this simplified transformation was explored, demonstrating that a range of primary and secondary benzylic alcohols are readily oxidized. In addition, the oxidation of allylic alcohols and hydroquinone can be achieved.
Excess Phosphine Ligand Plays a Critical Role in the Asymmetric Copper(I) Iodide‐Catalyzed Conjugate Addition of Grignard Reagents to α,β‐Unsaturated Esters
Authors: Wang Shun‐Yi , Song Ping , Loh Teck‐Peng
Published: December 2010

The role of excess ligand in the asymmetric 1,4‐conjugate addition (ACA) of Grignard reagents to α,β‐unsaturated esters compounds catalyzed by copper(I) iodide‐2,2′‐bis(di‐p‐tolylphosphino)‐1,1′‐binaphthyl (CuI‐Tol‐BINAP) is explored herein. In addition, this methodology allows asymmetric induction to be carried out using a non‐chiral phosphine copper complex with excess of a chiral phosphine ligand.
The Critical Role of Processing and Morphology in Determining Degradation Rates in Polymer Solar Cells
Authors: Kumar Ankit , Hong Ziruo , Sista Srinivas , Yang Yang
Published: December 2010

With rapid increase in the efficiencies of polymer solar cells (PSCs) in the last few years, the issue of device stability is taking center stage in organic photovoltaic research. In this work, the effects of oxygen and light on the degradation of charge‐transport properties of the bulk polymer active layer are studied over short timescales. It is shown that although different processing techniques produce similar efficiencies for pristine devices, they result in different degradation rates. This variation in degradation rates is primarily due to slightly different morphology parameters, such as molecular packing or disorder in the film. Investigation reveals that the choice of processing for the devices should consider degradation rates as a critical parameter, not just the efficiencies of the pristine devices. It was found that degradation starts with broadening of the effective density of states due to photo‐oxidation. Both transient absorption and charge extraction by linearly increasing voltage (CELIV) measurements show increase in disorder in the films with progressive degradation. It is suggested that annealing provides the necessary thermal energy to reduce the trap states by flattening out the energy landscape of the pristine films, improving not only the efficiency, as reported previously, but also slowing the degradation rates.
Body composition trajectories into adolescence according to age at pubertal growth spurt
Authors: Buyken Anette E. , Bolzenius Katja , Karaolis‐Danckert Nadina , Günther Anke L.B. , Kroke Anja
Published: December 2010

Objective: To investigate whether the development of body composition into adolescence differs among children with an early, average, or late pubertal growth spurt (age at take‐off [ATO]).

Methods: Mixed‐effect polynomial models were applied to serial anthropometric measurements spanning from 4 years before to 4 years after ATO in 215 DONALD participants. Sex‐specific trajectories of fat mass index (FMI, FM/m2), fat‐free mass index (FFMI, FFM/m2), and their z‐scores were compared among those with an early, average, or late ATO.

Results: Compared with girls with a late ATO (reference group), those with an early or average ATO experienced a significant increase in FFMI z‐scores [β (standard error) for linear trends in early and average ATO group: +0.15 (0.05) FFMI z‐scores/year (P = 0.001) and +0.11 (0.04) FFMI z‐scores/year (P = 0.005), respectively, adjusted for early life factors]. Similar differences were observed in boys [adjusted β (standard error): +0.20 (0.06) FFMI z‐scores/year (P = 0.0004) and +0.07 (0.05) FFMI z‐scores/year (P = 0.1), respectively]. Graphical illustration of the predicted trajectories revealed that differences in relative FFMI emerged from ATO onward. For FMI, comparison with late maturers showed a more pronounced quadratic trend (kg/m2/years2) (P = 0.01) among early‐maturing girls and a reduced linear trend in FMI z‐scores/year (P = 0.04) among early‐maturing boys.

Conclusions: This longitudinal study suggests that children who experience an early pubertal growth spurt accrue progressively more fat‐free mass during the first years of puberty than late‐maturing peers of the same age. Higher levels of adiposity commonly observed in adults with early puberty onset are, thus, likely to develop subsequently in later adolescence. Am. J. Hum. Biol., 2010. © 2010 Wiley‐Liss, Inc.
Correlations for prediction of specific surface area and bulk and apparent densities of porous styrene‐divinylbenzene copolymers
Authors: Nodehi Azizollah , Hajiebrahimi Mohammad , Parvazinia Mahmoud , Shahrokhi Mohammad , Abedini Hossein
Published: December 2010

Macroporous styrene‐divinylbenzene copolymers with different degree of crosslinking were prepared by suspension polymerization in presence of different binary mixtures of toluene and heptane, as diluent. Specific surface area, bulk and apparent densities, and pore volume of the resulting beads were determined experimentally. Applying the least square method to the experimental data, correlations for prediction of these properties were obtained. Effects of divinylbenzene concentration, diluent to comonomer volume ratio, and composition of the diluent mixture were considered in developing the aforementioned correlations. The influence of the reaction recipe on porous structure of the samples was also studied using scanning electron microscope (SEM). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and Supramolecular Self‐Assembly of Coil‐Rod‐Coil Molecules: The Relationship between Self‐Assembled Nanostructures and Molecular Structures
Authors: Chen Yulan , Zhang Fan , Zhu Bo , Han Yang , Bo Zhishan
Published: December 2010

Herein, the relationship between the supramolecularly self‐assembled nanostructures and the chemical structures of coil‐rod‐coil molecules is discussed. A series of nonamphiphilic coil‐rod‐coil molecules with different alkyl chains, central mesogenic groups, and chemical linkers were designed and synthesized. The solvent‐mediated supramolecular self‐assembling of these coil‐rod‐coil molecules resulted in rolled‐up nanotubes, nanofibers, submicron sized belts, needle‐like microcrystals, and amorphous structures. The self‐assembling behaviors of these coil‐rod‐coil molecules have been systematically investigated to reveal the relationship between the supramolecularly self‐assembled nanostructures and their chemical structures. With respect to the formation of rolled‐up nanotubes by self‐assembly of coil‐rod‐coil molecules, we have systematically investigated the following three influencing structural factors: 1) the alkyl chain length; 2) the central mesogenic group; (3) the linker type. These studies disclosed the key structural features of coil‐rod‐coil molecules for the formation of rolled‐up nanotubes.
Perylene‐Based Nanotweezers: Enrichment of Larger‐Diameter Single‐Walled Carbon Nanotubes
Authors: Backes Claudia , Schmidt Cordula D. , Hauke Frank , Hirsch Andreas
Published: December 2010

The solubilization of single‐walled carbon nanotubes (SWCNTs) by a novel tweezer‐shaped molecule with perylene bisimide moieties that act as aromatic anchoring groups is presented. Encouraging results of the tweezer‐dispersion concept is combined with the outstanding exfoliation and dispersion efficiencies of designed perylene bisimide derivatives, which have previously turned out as most‐powerful SWCNT dispersants. Based on the preferred interaction between the nanotweezer and SWCNTs with diameters larger than 0.8 nm, the supernatant was depleted after mild centrifugation in SWCNT species of smaller diameters. Characterization was carried out by a combination of UV/Vis and nIR absorption spectroscopy as well as emission spectroscopy of the SWCNTs and perylene. This study presents the foundation for a further improvement of selective SWCNT dispersion and sorting by designed molecules.
Ion flux and the function of endosomes and lysosomes: pH is just the start
Authors: Scott Cameron C. , Gruenberg Jean
Published: December 2010

The ionic nature of endosomes varies considerably in character along the endocytic pathway. Counter‐ion flux across the limiting membrane of endosomes has long been considered essential for full acidification and normal endosome/lysosomal function. The proximal functions of luminal ions, however, have been difficult to assess. The recent development of transgenic mice carrying mutations in the intracellular chloride channels (ClCs) has provided a tool to uncouple Cl− influx from endosomal acidification. Intriguingly, many of the defects of the endo‐lysomal system attributed to aberrant pH persist in the Cl−‐deficient mice implying a direct regulatory role for Cl− influx in endosome function. These observations may begin to explain the abundance of endosomal ion transporters, including ClCs, sodium‐proton exchangers, two‐pore channels and mucolipins, that have been localized to endo‐lysosomes, and the extensive changes in luminal ion composition therein. In this review, we summarize what is known regarding the mediators of endosomal ion flux, and discuss the implications of changing ionic content on endo‐lysosomal function.
Religion and the decision to donate organs: Exploring the potential role of religious leaders
Authors: Vincent Donald E. , Anker Ashley E. , Feeley Thomas H.
Published: December 2010

The two‐step flow model of communication (Katz, 1957) suggests opinion leaders obtain critical information from the mass media and, in turn, communicate this information to interpersonal contacts such as friends, family and co‐workers. It is suggested that religious leaders (RLs) may serve as opinion leaders on the topic of organ donation by debunking donation myths, promoting donation during worship services, or communicating the benefit of donation to families faced with the opportunity to participate in living or cadaveric donation. The current study examined the personal knowledge, experiences, and willingness to communicate about organ donation in a sample of RLs (N = 59) in Rochester, New York. Structured interviews were conducted in summer and fall of 2009 with a random sample of RLs. Results indicate a disparity between RLs' expressed personal support for donation and their engagement in donor registration. Approximately one‐quarter of RLs have spoken about donation during a religious service and many indicate their knowledge is not sufficient to discuss organ donation in detail. Results elaborate on how RLs may be trained to serve as opinion leaders in the promotion of organ donation. Copyright © 2010 John Wiley & Sons, Ltd.
A Pyrophosphate‐Responsive Gadolinium(III) MRI Contrast Agent
Authors: Surman Andrew J. , Bonnet Célia S. , Lowe Mark P. , Kenny Gavin D. , Bell Jimmy D. , Tóth Éva , Vilar Ramon
Published: December 2010

This study shows that the relaxivity and optical properties of functionalised lanthanide‐DTPA‐bis‐amide complexes (lanthanide=Gd3+ and Eu3+, DTPA=diethylene triamine pentaacetic acid) can be successfully modulated by addition of specific anions, without direct Ln3+/anion coordination. Zinc(II)‐dipicolylamine moieties, which are known to bind strongly to phosphates, were introduced in the amide “arms” of these ligands, and the interaction of the resulting Gd–Zn2 complexes with a range of anions was screened by using indicator displacement assays (IDAs). Considerable selectivity for polyphosphorylated species (such as pyrophosphate and adenosine‐5′‐triphosphate (ATP)) over a range of other anions (including monophosphorylated anions) was apparent. In addition, we show that pyrophosphate modulates the relaxivity of the gadolinium(III) complex, this modulation being sufficiently large to be observed in imaging experiments. To establish the binding mode of the pyrophosphate and gain insight into the origin of the relaxometric modulation, a series of studies including UV/Vis and emission spectroscopy, luminescence lifetime measurements in H2O and D2O, 17O and 31P NMR spectroscopy and nuclear magnetic resonance dispersion (NMRD) studies were carried out.
Concurrent Symmetries: The Interplay Between Local and Global Molecular Symmetries
Authors: Echeverría Jorge , Carreras Abel , Casanova David , Alemany Pere , Alvarez Santiago
Published: December 2010

We analyze in this article the degree to which different groups of atoms retain local symmetries when assembled in a molecule. This study is carried out by applying continuous symmetry measures to several families of mixed sandwiches, a variety of piano‐stool molecules, and several organic groups. An analysis of the local symmetry of the electron density shows that, sandwiched between two regions of different symmetry that correspond to the ligand sets, its symmetry is cylindrical at the central metal atom.
CFD modelling of dust explosions: Rapid combustion in a 20 L apparatus
Authors: Bind Vimlesh Kumar , Roy Shantanu , Rajagopal Chitra
Published: December 2010

Dust explosions are combustion of fine dust particles in a rapid reaction regime. They are of relatively common occurrence in industries which have unit operations like grinding, pneumatic conveying, drying, and fine particle collection: generally those units which handle fine particles or “dust” in an oxygen‐rich environment. At present, mitigation and prevention of dust explosion accidents is largely based on operator experience and safety inspection heuristics: knowledge that often cannot be documented or put into scientifically developed safety rules. Part reason for this state of affairs is our lack of fundamental understanding on how a dust explosion progresses after ignition of the dust cloud. In this contribution, with a view towards improving our understanding of dust explosions, we propose a multi‐scale modelling approach for modelling dust explosion phenomena in a standard 20 L Siwek Apparatus. The modelling approach is based on computational fluid dynamics methods treating Aluminum dust cloud as a quasi‐homogeneous phase.
Advances and opportunities at the interface between microbial bioenergy and nanotechnology
Authors: Pugh Shawn , McKenna Rebekah , Moolick Richard , Nielsen David R.
Published: December 2010

In this review, we highlight many recent developments in nanotechnology of critical relevance to microbial bioenergy synthesis. Nanoparticles, nanotubes, nanofibres, and nanoporous materials, are each being utilised in powerful ways as tools for feedstock processing, genetic engineering, and biofuel harvesting, as well as in bioelectrochemical systems. As materials and techniques continue to mature, nanomaterials will become a truly integral part of the bioenergy sector. Sustainable bioenergy production will ultimately be achieved through interdisciplinary efforts that continue to bridge the gap between these traditionally distinct fields of study.
Palmitoylated SDF1 α Shows Increased Resistance against Proteolytic Degradation in Liver Homogenates
Authors: Bellmann‐Sickert Kathrin , Beck‐Sickinger Annette G.
Published: December 2010

The chemokine stromal cell‐derived factor‐1 α (SDF1 α) is strongly involved in organogenesis, as well as inflammation and tissue repair, and acts by attracting different kinds of stem and progenitor cells. Therefore, it constitutes an interesting compound for drug development in regenerative medicine. However, it is prone to inactivation by proteolytic cleavage in human serum. Accordingly, it has to be stabilized against enzymatic degradation for any therapeutic application. We synthesized a palmitoylated SDF1 α analogue by native chemical ligation. Both the N‐terminal thioester and the C‐terminal palmitoylated fragment were prepared by solid‐phase peptide synthesis. The activity of the refolded and pure compound was determined by an inositol phosphate turnover assay and revealed no loss in receptor activation. Additionally, resistance to proteolytic degradation was investigated in porcine liver homogenates and showed a near sevenfold increased half time. This study is a proof of principle approach for the lipidation of SDF1 α and provides a basis for further engineering of the chemokine in order to increase its therapeutic value.
The theory of DQF‐COSY NMR experiments. I. Amplitude modulation of the signal
Authors: Kempgens P.
Published: December 2010

The two‐dimensional (2D) NMR double‐quantum filtered COSY spectrum of an AX spin system of spin‐1 has been calculated by numerical density matrix calculations. The basic phase cycle to achieve double quantum filtration consists of four steps. The total signal after these four steps is modulated in amplitude as a function of t1. It is therefore not possible to determine the sign of the modulation frequencies Ωu,t in a 2D complex Fourier transformation. Additional steps in the phase cycle are needed to achieve phase modulation. © 2010 Wiley Periodicals, Inc. Concepts Magn Reson Part A 36A: 341–346, 2010.
Head gradient coil for MRI with a window
Authors: Sánchez Clemente Cobos
Published: December 2010

Boundary element methods have been successfully used to design gradient coils for MRI. Here the full potential of this geometry‐independent technique is used to design head gradient coils, incorporating a rectangular window so as to allow visual interaction with the subject. The inclusion of the window can ameliorate significantly the claustrophobia perception in many subjects, as well as, it allows visual stimuli necessary for certain fMRI experiments to be displayed. This work details some numerical examples for the design of torque‐balanced coils of minimum inductance, where the incorporation of the window is shown to improve visual interaction with the subject compared with conventional coils. © 2010 Wiley Periodicals, Inc. Concepts Magn Reson Part A 36A: 388–393, 2010
Neuronal polarity in Drosophila: Sorting out axons and dendrites
Authors: Rolls Melissa M.
Published: December 2010

Drosophila neurons have identifiable axons and dendrites based on cell shape, but it is only just starting to become clear how Drosophila neurons are polarized at the molecular level. Dendrite‐specific components including the Golgi complex, GABA receptors, neurotransmitter receptor scaffolding proteins, and cell adhesion molecules have been described. Proteins involved in constructing presynaptic specializations are concentrated in axons of some neurons. A very simple model for how these components are distributed to axons and dendrites can be constructed based on the opposite polarity of microtubules in axons and dendrites: dynein carries cargo into dendrites, and kinesins carry cargo into axons. The simple model works well for multipolar neurons, but will likely need refinement for unipolar neurons, which are common in Drosophila. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 71: 419–429, 2011
Maintenance of neuronal polarity
Authors: Szu‐Yu Ho Tammy , Rasband Matthew N.
Published: December 2010

Neurons are highly polarized cells with distinct domains responsible for receiving, transmitting, and propagating electrical signals. Central to these functions is the axon initial segment (AIS), a short region of the axon adjacent to the cell body that is enriched in voltage‐gated ion channels, cell adhesion molecules, and cytoskeletal scaffolding proteins. Traditionally, the function of the AIS has been limited to its role in action potential initiation and modulation. However, recent experiments indicate that it also plays essential roles in neuronal polarity. Here, we review how initial segments are assembled, and discuss proposed mechanisms for how the AIS contributes to maintenance of neuronal polarity. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 71: 474–482, 2011
The role of Rho GTPase proteins in CNS neuronal migration
Authors: Govek Eve‐Ellen , Hatten Mary E. , Van Aelst Linda
Published: December 2010

The architectonics of the mammalian brain arise from a remarkable range of directed cell migrations, which orchestrate the emergence of cortical neuronal layers and pattern brain circuitry. At different stages of cortical histogenesis, specific modes of cell motility are essential to the stepwise formation of cortical architecture. These movements range from interkinetic nuclear movements in the ventricular zone, to migrations of early‐born, postmitotic polymorphic cells into the preplate, to the radial migration of precursors of cortical output neurons across the thickening cortical wall, and the vast, tangential migrations of interneurons from the basal forebrain into the emerging cortical layers. In all cases, actomyosin motors act in concert with cell adhesion receptor systems to provide the force and traction needed for forward movement. As key regulators of actin and microtubule cytoskeletons, cell polarity, and adhesion, the Rho GTPases play critical roles in CNS neuronal migration. This review will focus on the different types of migration in the developing neocortex and cerebellar cortex, and the role of the Rho GTPases, their regulators and effectors in these CNS migrations, with particular emphasis on their involvement in radial migration. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 71: 528–553, 2011
Synthesis of Fluorescence‐Labelled Glycosidic Prodrugs Based on the Cytotoxic Antibiotic Duocarmycin (Eur. J. Org. Chem. 36/2010)
Authors: Tietze Lutz F. , Behrendt Frank , Major Felix , Krewer Birgit , von Hof J. Marian
Published: December 2010

The cover picture shows live‐cell images of novel fluorescence‐labelled Duocarmycin analogues. Images a and b represent the cellular uptake of the new compound at λexc = 405 nm and λem = 500 nm (a) and at λexc = 514 nm and λem = 560 nm (b), whereas image c shows the overlap of a and b. Images d and f show colocalisation experiments with Hoechst 33342 (d) and MitoTracker® DeepRed (f), whereas image e shows the cellular uptake of the new compound (λexc = 514 nm, λem = 560 nm) again for comparison with MitoTracker® DeepRed. Details are discussed in the article by L. F. Tietze et al. on p. 6909 ff.