bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling the Growth Kinetics of Fluidized‐Bed Spray Granulation
Authors: Li Z. , Kind M. , Gruenewald G. 
Published: May 2011

AbstractFluidized‐bed spray granulation is used to produce porous granular particles from suspensions, solutions, and melts. In this work, the adapted two‐fluid model approach is used to simulate the fluid dynamics in the fluidized bed, and a simplified direct quadrature method of moments is adopted to mimic the full particle size distribution. The size‐dependent growth kinetics is obtained by computational fluid dynamics simulation for short process times from the modeling of drop deposition on the particles. This kinetics is used in the population balance equation to predict the evolution of the full particle size distribution for long process times. Such a multiscale approach allows for a description of continuous granulation processes.
Particle Residence Times in Fluidized Bed Granulation Equipments
Authors: Börner M. , Peglow M. , Tsotsas E. 
Published: May 2011

AbstractVarious types of fluidized bed equipments used in granulation were experimentally investigated in order to gain a more detailed insight in particle recirculation behavior and particle residence times in the two considered compartments, namely the spray compartment and the drying compartment. The investigated fluidized bed technologies comprise a top‐spray process, a spout fluidized bed without and with internal riser, and a spouted bed. The measurements were conducted by using image analysis techniques on an almost 2D particle flow. From the results, conclusions about particle wetting and drying can be extracted, subject to fluidization velocity, nozzle mass flow rate, and facility/riser construction.
Influence of the Spray Method on Product Quality and Morphology in Spray Drying
Authors: Walzel P. 
Published: May 2011

AbstractThe spraying system is responsible for the particle formation and spray pattern. The most important features of sprays emerging from different atomizers are discussed. In the case of pneumatic atomizers the entrainment is low and a well‐mixed jet with little segregation of fine and large particles occurs. A much stronger interaction of gas and spray takes place in the case of large spray angles as, e.g., produced by rotary atomizers. To some extent the particle morphology is known to depend on the drying speed and thus on the entrainment.
Facile Fabrication of Hollow Mesoporous Silica Nanospheres for Superhydrophilic and Visible/Near‐IR Antireflection Coatings
Authors: Du Xin , He Junhui 
Published: May 2011

AbstractA series of hierarchically mesostructured silica nanoparticles (MSNs) less than 100 nm in size were fabricated by means of a one‐step synthesis using dodecanethiol (C12SH) and cetyltrimethylammonium bromide (CTAB) as the dual template, and trimethylbenzene (TMB) as the swelling agent. Silica nanoparticles with varied morphologies and structures, including mesoporous silica nanoparticles with tunable pore size, mesoporous silica nanoparticles with a thin solid shell, hollow mesoporous silica nanoparticles with tunable cavity size, and hollow mesoporous silica nanoparticles with a thin solid shell, were obtained by regulating the TMB/CTAB molar ratio and the stirring rate with the assistance of C12SH. Silica particulate coatings were successfully fabricated by using MSNs with varied morphologies and structures as building block through layer‐by‐layer dip‐coating on glass substrates. The thickness and roughness of the silica particulate coatings could be tailored by regulating the deposition cycles of nanoparticles. The silica particulate coatings composed of hollow mesoporous silica nanoparticles with a thin shell (S2) increased the maximum transmittance of slide glass from 90 to 96 %, whereas they reduced its minimum reflection from 8 to 2 % at the optimized wavelength region that could be adjusted from visible to near‐IR with a growing number of deposition cycles. The coatings also exhibited excellent superhydrophilic and antifogging properties. These mesostructured silica nanoparticles are also expected to serve as ideal scaffolds for biological, medical, and catalytic applications.
Spectroelectrochemical Evidence for the Nitrosyl Redox Siblings NO+, NO., and NO− Coordinated to a Strongly Electron‐Accepting FeII Porphyrin: DFT Calculations Suggest the Presence of High‐Spin States after Reduction of the FeII–NO− Complex
Authors: Pellegrino Juan , Hübner Ralph , Doctorovich Fabio , Kaim Wolfgang 
Published: May 2011

AbstractExperimental and computational results for the electron‐deficient porphyrin complex [Fe(NO)(TFPPBr8)] (1; TFPPBr8=2,3,7,8,12,13,17,18‐octabromo‐5,10,15,20‐tetrakis(pentafluorophenyl)porphyrin) are reported with respect to its electron‐transfer behavior. Complex 1 undergoes three one‐electron processes: two reversible reductions and one irreversible oxidation. Spectroelectrochemical measurements (IR and UV/Vis/NIR spectroscopy) of 14NO‐ and 15NO‐containing material indicate that the first reduction to 1− occurs largely on the NO ligand to produce nitroxyl anion (NO−) character, as evident from the considerable change in νNO from 1715 to around 1550 cm−1. The second reduction to 12− does not result in a further shift of νNO to lower frequencies, but to a surprising high‐energy shift to 1590 cm−1. This and the notable changes of the characteristic porphyrin vibrations as well as significant changes of the UV/Vis absorptions indicate a porphyrin‐centered process; DFT calculations predict the shift of νNO to higher frequencies for the intermediate‐ and high‐spin states of 12−. The oxidation of 1 is irreversible on the voltammetry timescale, but chemically reversible in spectroelectrochemical experiments, suggesting that the cationic form dissociates to the corresponding ferric porphyrin and NO. DFT calculations support the interpretation of the experimental results.
Understanding the Acid–Base Properties of Adenosine: The Intrinsic Basicities of N1, N3 and N7
Authors: Kapinos Larisa E. , Operschall Bert P. , Larsen Erik , Sigel Helmut 
Published: May 2011

AbstractAdenosine (Ado) can accept three protons, at N1, N3, and N7, to give H3(Ado)3+, and thus has three macro acidity constants. Unfortunately, these constants do not reflect the real basicity of the N sites due to internal repulsions, for example, between (N1)H+ and (N7)H+. However, these macroconstants are still needed for the evaluations and the first two are taken from our own earlier work, that is, ${{\rm{p}}K_{{\rm{H}}_{\rm{3}} {\rm{(Ado)}}}^{\rm{H}} }$=−4.02 and ${{\rm{p}}K_{{\rm{H}}_{\rm{2}} {\rm{(Ado)}}}^{\rm{H}} }$=−1.53; the third one was re‐measured as ${{\rm{p}}K_{{\rm{H(Ado)}}}^{\rm{H}} }$=3.64±0.02 (25 °C; I=0.5 M, NaNO3), because it is the main basis for evaluating the intrinsic basicities of N7 and N3. Previously, contradicting results had been published for the micro acidity constant of the (N7)H+ site; this constant has now been determined in an unequivocal manner, and that of the (N3)H+ site was obtained for the first time. The micro acidity constants, which describe the release of a proton from an (N)H+ site under conditions for which the other nitrogen atoms are free and do not carry a proton, decrease in the order ${{\rm{p}}k_{{\rm{N7(Ado)N1}} \cdot {\rm{H}}}^{{\rm{N7}} - {\rm{N1}}} }$=3.63±0.02 > ${{\rm{p}}k_{{\rm{H}} \cdot {\rm{N7(Ado)N1}}}^{{\rm{N7}} - {\rm{N1}}} }$=2.15±0.15 > ${{\rm{p}}k_{{\rm{H}} \cdot {\rm{N3(Ado)N1}}{\rm{,N7}}}^{{\rm{N3}} - {\rm{N1}}{\rm{,N7}}} }$=1.5±0.3, reflecting the decreasing basicity of the various nitrogen atoms, that is, N1>N7>N3. Application of the above‐mentioned microconstants allows one to calculate the percentages (formation degrees) of the tautomers formed for monoprotonated adenosine, H(Ado)+, in aqueous solution; the results are 96.1, 3.2, and 0.7 % for N7(Ado)N1⋅H+, +H⋅N7(Ado)N1, and +H⋅N3(Ado)N1,N7, respectively. These results are in excellent agreement with theoretical DFT calculations. Evidently, H(Ado)+ exists to the largest part as N7(Ado)N1⋅H+ having the proton located at N1; the two other tautomers are minority species, but they still form. These results are not only meaningful for adenosine itself, but are also of relevance for nucleic acids and adenine nucleotides, as they help to understand their metal ion‐binding properties; these aspects are briefly discussed.
Unidirectional Redox‐Stimulated Movement around a CC Single Bond
Authors: Tepper Christina , Haberhauer Gebhard 
Published: May 2011

AbstractA remarkable challenge for the design of molecular machines is the realization of a synchronized and unidirectional movement caused by an external stimulus. Such a movement can be achieved by a unidirectionally controlled change of the conformation or the configuration. Biphenol derivatives are one possibility to realize a redox‐driven unidirectional molecular switch. For this reason, a 4,4′‐biphenol derivative was fixed to a chiral cyclopeptidic scaffold and stimulated by chemical oxidants and reduction agents. The conformation of the switch was determined by DFT calculations by using B3LYP and the 6‐31G* basis set. The switching process was observed by UV and circular dichroism (CD) spectroscopic measurements. Several oxidation agents and various conditions were tested, among which (diacetoxy)iodobenzene (DAIB) in methanol proved to be the best. In this way it was possible to synthesize a redox‐stimulated molecular switch with a movement that is part of a rotation around a biaryl binding axis.
Investigation of Aromaticity and Photophysical Properties in [18]/[20]π Porphycene Derivatives
Authors: Kim Kil Suk , Sung Young Mo , Matsuo Takashi , Hayashi Takashi , Kim Dongho 
Published: May 2011

AbstractIn this study, we have investigated the relationship between aromaticity and photophysical properties of trifluoromethyl‐substituted [18]/[20]π porphycenes by using theoretical calculations and various spectroscopic methodologies. Interestingly, we have found that the HOMO–LUMO gap of [20]π porphycene is larger than that of [18]π porphycene, which is in a sharp contrast with those of typical [4n]/[4n+2]π porphyrinoids. Based on our observations, we demonstrate that the origin of this contrasting feature of [20]π porphycene arises from the uniquely large energy splitting between LUMO and LUMO+1 of [18]π porphycene compared with other aromatic [4n+2]π porphyrinoids with nearly degenerate LUMO/LUMO+1. Consequently, we can propose that the energy difference between LUMO and LUMO+1 levels of aromatic [4n+2]π porphyrinoids is an important factor in determining the electronic nature of their corresponding antiaromatic [4n]π porphyrinoids. Moreover, to the best of our knowledge, this is the first study to illustrate the photophysical properties of porphycenes with [4n]π electronic circuits.
Chiral Metallo–Supramolecular Complexes Selectively Induce Human Telomeric G‐Quadruplex Formation under Salt‐Deficient Conditions
Authors: Zhao Chuanqi , Geng Jie , Feng Lingyan , Ren Jinsong , Qu Xiaogang 
Published: May 2011

AbstractChiral molecular recognition of human telomeric DNA is important for rational drug design and developing structural probes of G‐quadruplexes. Here we report that a chiral supramolecular complex can selectively induce human telomeric G‐quadruplex formation and discriminate different G‐quadruplex sequences under salt‐deficient conditions studied by circular dichroism (CD), UV meltings, stopped‐flow spectroscopy, fluorescence resonance energy transfer, enzyme cleavage, and gel electrophoresis. P‐enantiomer induced G‐quadruplex formation is fast and does not require a large excess of P enantiomer. More importantly, this chiral compound induces loop sequence‐dependent G‐quadruplex formation.
Homogeneous Nucleophilic Radiofluorination and Fluorination with Phosphazene Hydrofluorides
Authors: Mathiessen Bente , Jensen Andreas T. I. , Zhuravlev Fedor 
Published: May 2011

AbstractA series of phosphazenium hydrofluorides, P1tBu⋅[18/19F]HF, P1tOct⋅[18/19F]HF, P2Et⋅[18/19F]HF, and P4tBu⋅[18/19F]HF, was synthesized. The radioactive phosphazenium [18F]hydrofluorides were obtained by the one‐step formation and trapping of gaseous [18F]HF with the respective phosphazene bases. The [19F] isotopomers were prepared from the corresponding phosphazene bases and Et3N⋅3HF. Under the design of experiment (DoE)‐optimized conditions, P2Et⋅HF and P4tBu⋅HF fluorinated alkyl chlorides, bromides, and pseudohalides in 76–98 % yield, but gave lower yields with iodides and electron‐deficient arenes. DoE models showed that fluorination can be performed in glass vessels, and that the reactivity of P2Et⋅HF and P4tBu⋅HF is dominated by solvent polarity but is insensitive to water to at least 2 equiv. In contrast, P1tBu⋅HF and P1tOct⋅HF were unstable towards autofluorolysis. DFT calculations were performed to rationalize this finding in terms of diminished steric bulk, higher Parr’s electrophilicity, and chemical hardness of P1RH+. The corresponding radiofluorination reaction gave no valid DoE model but displayed similar substrate scope. High specific activity and excellent radiochemical yields with various pseudohalides (81–91 %) suggest that the proposed radiofluorination methodology can complement the current [18F]KF/Kryptofix methods, particularly in the areas for which nonpolar reaction conditions are required.
Controlled Self‐Assembly of Re‐engineered Insulin by FeII
Authors: Munch Henrik K. , Heide Søren Thiis , Christensen Niels Johan , Hoeg‐Jensen Thomas , Thulstrup Peter W. , Jensen Knud J. 
Published: May 2011

AbstractSelf‐assembly of proteins mediated by metal ions is crucial in biological systems and a better understanding and novel strategies for its control are important. An abiotic metal ion ligand in a protein offers the prospect of control of the oligomeric state, if a selectivity over binding to the native side chains can be achieved. Insulin binds ZnII to form a hexamer, which is important for its storage in vivo and in drug formulations. We have re‐engineered an insulin variant to control its self‐assembly by covalent attachment of 2,2′‐bipyridine. The use of FeII provided chemoselective binding over the native site, forming a homotrimer in a reversible manner, which was easily followed by the characteristic color of the FeII complex. This provided the first well‐defined insulin trimer and the first insulin variant for which self‐assembly can be followed visually.
Fast, Ligand‐ and Solvent‐Free Synthesis of 1,4‐Substituted Buta‐1,3‐diynes by Cu‐Catalyzed Homocoupling of Terminal Alkynes in a Ball Mill
Authors: Schmidt Robert , Thorwirth Rico , Szuppa Tony , Stolle Achim , Ondruschka Bernd , Hopf Henning 
Published: May 2011

AbstractA method for the Glaser coupling reaction of alkynes by using a vibration ball mill has been developed. The procedure avoids the use of ligands and solvents during the reaction. Aryl‐ and alkyl‐substituted terminal alkynes undergo homocoupling if coground with KF–Al2O3 and CuI as a milling auxiliary and catalyst. Furthermore, an alternative protocol has been developed incorporating 1,4‐diazabicyclo[2.2.2]octane (DABCO) as an additional base allowing the use of KF–Al2O3 with a lower KF loading. Besides Cu salts, the homocoupling of phenylacetylene is also catalyzed by Ni or Co salts, as well as by PdCl2. TMS‐protected phenylacetylene could be directly converted into the homocoupling product after in situ deprotection of the alkyne by fluoride‐initiated removal of the trimethylsilyl group.
Four Iodine‐Mediated Electrophilic Cyclizations of Rigid Parallel Triple Bonds Mapped from 1,8‐Dialkynylnaphthalenes
Authors: Chen Xiaopeng , Lu Ping , Wang Yanguang 
Published: May 2011

AbstractFour different types of fused arenes, including fluoranthene, indeno[2,1‐a]phenalene, (8H)cyclopenta[a]acenaphthylene, and pyridine[a]acenaphthylene, were efficiently constructed through iodine‐mediated electrophilic cyclizations of 1,8‐dialkynyl naphthalenes in a single step. Theoretical calculations supported our hypothesis that these reactions had high regioselectivity. Oxidative coupling of the fluoranthene skeleton, followed by aromatization, effectively synthesized perylene derivative 14, which emitted light at 597 nm in dichloromethane with an emission efficiency of 0.81 referred to 5,6,11,12‐tetraphenylnaphthacene as a standard.
Synthesis of a Large Functional Cage Compound Based on Four GaGa Single Bonds and Its Application as an Oligoacceptor: On the Way to Bio‐Organogallium Hybrid Molecules
Authors: Uhl Werner , Voß Matthias , Müller Jens , Seubert Kristof 
Published: May 2011

AbstractThe digallium compound R2GaGaR2 (1; R=CH(SiMe3)2) reacts with citracinic acid by the release of two equivalents of bis(trimethylsilyl)methane and the formation of a unique oligofunctional cage compound (2). Four GaGa bonds in a tetrahedral arrangement are bridged by four spacer ligands that are located on the faces of the tetrahedron and bridge the gallium atoms of three different GaGa bonds. Four pyridinium groups result from the shift of one of the three acidic protons of four citracinic acid molecules to the nitrogen atoms of the aromatic rings. The NH groups are arranged in pairs and are capable of acting as chelating acceptors for the coordination of THF molecules (2(THF)2) or the nitrogen atoms of 1‐deazapurine (3(OEt2)4). In particular, the last reaction verifies the potential applicability of this relatively water‐ and air‐resistant acceptor compound for the generation of bioorganometallic hybrid molecules.
Investigation of Chemical Compositions of Urban, Industrial, Agricultural, and Rural Top‐soils in Izmir, Turkey
Authors: Yatkin Sinan , Bayram Abdurrahman 
Published: May 2011

AbstractThe top‐soil samples were collected from urban, industrial, agricultural, and rural sites to investigate the modification in the elemental composition due to anthropogenic influence in one of the biggest city of Turkey, namely Izmir. The elemental profiles were dominated by lithophilic elements such as Al, Ca, Fe, Mg, K, and sea salt element, Na, which is typical for Mediterranean region. The trace elemental concentrations showed significant variation with higher concentrations in the industrial sites, particularly in the vicinity of iron‐steel producers from scrap materials (EAF‐Steels). Lead, Zn, and Cd around EAF‐Steels were found to be higher than other sites. Comparison to universal upper crusts and local reference soil has shown that Izmir top‐soils were contaminated in terms of many trace elements, most probably due to anthropogenic activities. Correlation matrix, crustal enrichment factors, and factor analysis were applied to investigate the extent of soil modification and possible sources. The results indicated that the elemental profiles of top‐soils were mainly determined by parent materials; however, anthropogenic activities were found to be factor effective on the profile.
Concurrent FFT computing on multicore processors
Authors: Barhen J. , Humble T. , Mitra P. , Imam N. , Schleck B. , Kotas C. , Traweek M. 
Published: May 2011

SUMMARYThe emergence of streaming multicore processors with multi‐SIMD (single‐instruction multiple‐data) architectures and ultra‐low power operation combined with real‐time compute and I/O reconfigurability opens unprecedented opportunities for executing sophisticated signal processing algorithms faster and within a much lower energy budget. Here, we present an unconventional Fast Fourier Transform (FFT) implementation scheme for the IBM Cell, named transverse vectorization. It is shown to outperform (both in terms of timing and GFLOP throughput) the fastest FFT results reported to date for the Cell in the open literature. We also provide the first results for multi‐FFT implementation and application on the novel, ultra‐low power Coherent Logix HyperX processor. Copyright © 2011 John Wiley & Sons, Ltd.
Worst‐case execution time analysis‐driven object cache design
Authors: Huber Benedikt , Puffitsch Wolfgang , Schoeberl Martin 
Published: May 2011

SUMMARYHard real‐time systems need a time‐predictable computing platform to enable static worst‐case execution time (WCET) analysis. All performance‐enhancing features need to be WCET analyzable. However, standard data caches containing heap‐allocated data are very hard to analyze statically. In this paper we explore a new object cache design, which is driven by the capabilities of static WCET analysis. Simulations of standard benchmarks estimating the expected average case performance usually drive computer architecture design. The design decisions derived from this methodology do not necessarily result in a WCET analysis‐friendly design. Aiming for a time‐predictable design, we therefore propose to employ WCET analysis techniques for the design space exploration of processor architectures. We evaluated different object cache configurations using static analysis techniques. The number of field accesses that can be statically classified as hits is considerable. The analyzed number of cache miss cycles is 3–46% of the access cycles needed without a cache, which agrees with trends obtained using simulations. Standard data caches perform comparably well in the average case, but accesses to heap data result in overly pessimistic WCET estimations. We therefore believe that an early architecture exploration by means of static timing analysis techniques helps to identify configurations suitable for hard real‐time systems. Copyright © 2011 John Wiley & Sons, Ltd.
Surfactin Self‐Assembles into Direct and Reverse Aggregates in Equilibrium and Performs Selective Metal Cation Extraction
Authors: Déjugnat Christophe , Diat Olivier , Zemb Thomas 
Published: May 2011

AbstractOn tie‐lines between water‐rich and alkane‐rich solutions, it is shown via scattering experiments that natural lipopeptide surfactin self‐assembles into direct and reverse micelles in equilibrium. Elongated direct micelles in the aqueous phase are present together with small reverse globular aggregates in the organic phase. These latter are made from hydrated surfactant without any “water pool” in the organic phase. The resulting biphasic system is used for liquid–liquid extraction of model metal cations. It is efficient with iron but not with copper or neodymium. Competitive extractions show high selectivity towards iron.