bluuebunny/crossref_metadata_2025 huggingface dataset:
Model Assessment for the Prediction of Mass Transfer Coefficients in Liquid‐Liquid Extraction Columns
Authors: Outili N. , Meniai A.‐H. , Gneist G. , Bart H.‐J.
Published: May 2007

A large number of theories are reported in the literature for the calculation of individual mass transfer coefficients and each has a well defined application range, which depends on the nature of the continuous and the dispersed phases. Each theory is also based on a different transfer mode, e.g., the dispersed phase depends essentially on the drop behavior, which is directly related to the drop size. However, an accurate determination of the overall mass transfer coefficient depends upon the choice of the combination of theories to be used for the calculation of the individual mass transfer coefficients, i.e., for the continuous and dispersed phases. In the present work, different combinations for the calculation of the overall mass transfer coefficient have been tested for the commonly recommended Acetone/Toluene/Water system, which is characterized by relatively large drop sizes.
Experimental and Numerical Studies of Fe2O3 Particle Formation Processes in a Flat Flame Burner
Authors: Beck M. , Wirtz S. , Scherer V.
Published: May 2007

Particle formation processes are of interest for many industrial applications. This work focuses on investigating Fe2O3 particle formation. The particles form during thermal decomposition of an iron chloride solution in so‐called spray roasting reactors. To analyze the reaction process, a laboratory reactor was designed which reproduces the conditions required for a systematic study of the particle formation process. Furthermore, a simplified particle conversion model was developed to simulate the realistic geometries and particle numbers on an industrial scale by CFD codes.
Controlled Fabrication of Highly Oriented ZnO Microrod/Microtube Arrays on a Zinc Substrate and Their Photoluminescence Properties
Authors: Liu Yang , Chu Ying , Li Li‐Li , Dong Li‐Hong , Zhuo Yu‐Jiang
Published: May 2007

Well‐aligned zinc oxide microrod and microtube arrays with high aspect ratios were fabricated on zinc foil by a simple solution‐phase approach in an aqueous solution of ethylenediamine (en). The shape of the ZnO microstructures can be easily modulated from rods to tubes by adding cetyl trimethyl ammonium bromide (CTAB) into the reaction system. Control experiments demonstrate that some reaction parameters, such as the concentration of ethylenediamine, the kind of surfactant, reaction time, and the temperature, all have direct influences on the morphology of the products. Based on the early structure arising from arrested growth (nanosheets), a reasonable mechanism for the growth of ZnO microrods and microtubes has been proposed. The products were characterized by X‐ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence emission.
Photosensitization and the Photocurrent Switching Effect in Nanocrystalline Titanium Dioxide Functionalized with Iron(II) Complexes: A Comparative Study
Authors: Macyk Wojciech , Stochel Grażyna , Szaciłowski Konrad
Published: May 2007

Selected iron(II) complexes (ferrocene, ferrocenylboronic acid, hexacyanoferrate(II)) have been used as photosensitizers of titanium dioxide. Various types of electronic interactions between the surface complex and the semiconducting support are reflected in different yields of photocurrent generated upon visible‐light irradiation and different efficiencies of the photosensitization effect. The studied systems, showing the photocurrent switching upon changes of electrode potential and energy of photons (the PEPS effect), are good models of simple photoelectrochemical logic devices. The mechanism of photosensitization and photocurrent switching is discussed with respect to the type of surface‐complex–support interaction. Quantum‐mechanical calculations support the proposed mechanisms.
Continuous Enantioselective Kinetic Resolution of Terminal Epoxides Using Immobilized Chiral Cobalt—Salen Complexes.
Authors: Solodenko Wladimir , Jas Gerhard , Kunz Ulrich , Kirschning Andreas
Published: May 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Structural and Functional Basis of Cyclooxygenase Inhibition
Authors: Blobaum Anna L. , Marnett Lawrence J.
Published: May 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
MTBE (Methyl‐tert.‐butylether) ‐ moderne Katalyse im Unterricht
Authors: Warntjes Sabine , Eilks Ingo , Ralle Bernd
Published: May 2007

METHYL‐TERT.‐BUTYLETHER (MTBE) ist ein Erzeugnis der chemischen Grundstoffindustrie, das in den vergangenen zehn Jahren einen starken Produktionsanstieg zu verzeichnen hatte. Es wird aufgezeigt, auf welchen Wegen verschiedene Aspekte der modernen Herstellung von MTBE in einem problem‐ und projektorientierten Experimentalunterricht thematisiert werden können. In diesem Zusammenhang werden vergleichende, einfach durchzuführende Untersuchungen zur Aktivität verschiedener Festkörpersäuren (Ionenaustauscherharze, Tone und Zeolithe) vorgestellt und damit ein Einblick in neuere Entwicklungen der heterogenen Katalyse gegeben.
RIM3γ is a postsynaptic protein in the rat central nervous system
Authors: Liang Fengyi , Zhang Bin , Tang Junhong , Guo Jing , Li Wenbo , Ling Eng Ang , Chu Haiying , Wu Yajun , Chan Yee Gek , Cao Qiong
Published: May 2007

RIMs (Rab3‐interacting molecules) are synaptic proteins essential for neural transmission and plasticity. RIM1α has been implicated in membrane trafficking and regulation of secretory vesicle exocytosis in eukaryotic cells. Little information is as yet available on RIM3γ. In the present study, we investigated the cellular expression, subcellular distribution, and possible functions of RIM3γ in the rat CNS. Rim3γ cDNA was subcloned and the protein expressed in vitro for the generation and purification of a rabbit anti‐RIM3γ polyclonal antibody. In situ hybridization histochemistry, immunohistochemistry, and immunoelectron microscopy were performed to map expression of the mRNA and protein in the rat CNS. Our results indicated widespread distribution of RIM3γ in diverse CNS neuronal cell types. The mRNA was found mainly in the cell bodies, whereas the protein immunoreactivity was localized chiefly to neuronal dendrites and to the postsynaptic densities as visualized under the light and electron microscope. This postsynaptic placement of RIM3γ is distinct from the presynaptic localization of RIM1α but may contribute to regulating synaptic transmission and plasticity. The identification of RIM3γ as a postsynaptic protein has functional implications for CNS synapse functions. J. Comp. Neurol. 503:501–510, 2007. © 2007 Wiley‐Liss, Inc.
Electron Density and Bonding in Borates: An Experimental Study of Tetrabutylammonium Heptahydridohexaborate, [(C4H9)4N][B6H7]
Authors: Förster Diana , Scheins Stephan , Luger Peter , Lentz Dieter , Preetz Wilhelm
Published: May 2007

An experimental study of a high‐resolution X‐ray data set of the closo‐boranate [B6H7]– was performed. The charge density distribution and its topological properties were analyzed according to the “Atoms in Molecules” theory of R. W. Bader. The [B6H7]– anion forms an octahedral boron cage with one of the six faces capped by an additional proton. The unusual bonding situation of the threefold capping hydrogen atom is of special interest and is discussed in detail. Three new B–H bonds form, while the B–B bonds in the capped boron triangle vanish. The reactivity of the [B6H7]– anion is visualized by the electrostatic potential.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
On the clarity of expressive and contextual information in the recognition of emotions: A methodological critique
Authors: Fernandez‐Dols Jose‐Miguel , Sierra Benjamin , Ruiz‐Belda M. Angeles
Published: May 2007

Ekman, Friesen and Ellsworth's (1982b) influential review on emotional expression and context prescribed the current standard criteria for selecting clear and comparable faces and contexts. These recommendations might not pay enough attention to the peculiarities of contextual information. Criteria of clarity for contextual stimuli should be grounded in the process of categorization of social situations (e.g. prototypicality and salience). A set of criteria of contextual clarity were designed according to this line of argument. The resulting contextual stimuli were employed in a replication of Wallbott's (1988) experiment on recognition of emotions through discrepant sources of information. In contrast with previous studies, subjects' judgments were equally predictable from expression and context.
Person perception through facial photographs: Effects of glasses, hair, and beard on judgments of occupation and personal qualities
Authors: Hellström Åke , Tekle Joseph
Published: May 2007

Thirty‐two photographs of male faces, four for each combination of the presence and absence of glasses, hair, and beard, were rated by 75 judges on 23 scales, assessing the typicality for 15 occupations as well as eight personal qualities. The effects of facial attributes on ratings formed characteristic profiles for the different scales. The pattern of correlations between facial attributes and factor scores from a factor analysis of the ratings indicates that the judges associated wearing glasses with intellectualism and goodness, being bald with idealism, and wearing a beard with unconventionality and goodness. In two further experiments, judges were to identify each of three faces with one of three or four occupations; the results confirmed the operativeness of the profiles from the rating experiment.
Internalization of conflict and attitude change
Authors: Pérez Juan Antonio , Falomir Juan Manuel , Mugny Gabriel
Published: May 2007

In a 2 × 2 × 2 design, eighty smokers were exposed to an anti‐smoking appeal attributed either to an expert source (superior status) or a minority source (inferior status). Subjects were either allowed or not to smoke during the experiment. In addition subjects had to memorize part of the appeal and a recall task either followed after reading the appeal (completed task) or not (uncompleted task). The results show that the expert source produces more attitude change than the minority when the tension induced by the source is weakened (either by the opportunity to smoke or task completion). In contrast the minority has more impact when subjects are not able to smoke or when the task is not completed, which is to say when the conflict has been internalized. An explanation of these effects is offered in terms of the more defensive forms of resistance involved with respect to sources of superior status compared to more assertive forms with respect to minorities.
Analysis of amino acids by combination of carrier ampholyte‐free IEF with ITP
Authors: Procházková Barbora , Glovinová Eliška , Pospíchal Jan
Published: May 2007

The use of carrier ampholyte‐free IEF (CAF‐IEF) with ITP mobilization and conductivity detection in ITP mode for preconcentration and analysis of amino acids is demonstrated. The analytical procedure consists of three subsequent steps. In the first step, amino acids are continuously dosed from an infinite volume reservoir by electromigration to the column, where a sharp, stationary neutralization reaction boundary (NRB) is created in between acidic and basic primary electrolyte. Here, amino acids are selectively focused (trapped), if their pI falls to the pH difference on both sides of the NRB (pH gap). Amino acids create sharp rectangular zones, arranged according to their pI values. In the second step, focused zones are mobilized. After accumulation of the detectable amount of amino acids, dosing electrolyte in the infinite volume reservoir is changed for the mobilizing electrolyte. The migration mode is changed from CAF‐IEF to ITP and substances start to migrate toward the analytical capillary. In the third step, analytes are transferred into the analytical column equipped with a conductivity detector and are detected in the new leading electrolyte in an ITP migration mode. The presented CAF‐IEF‐ITP‐ITP with time‐dependent accumulation of the large‐volume sample enables to achieve in a reasonable time a 100 times lower c‐LOD (here in orders of nmol/L), than can be reached by conventional hyphenated ITP‐ITP.
Profiling recombinant major birch pollen allergen Bet v 1a and carbamylated variants with CZE and CIEF
Authors: Kronsteiner Barbara , Malissa Hans , Stutz Hanno
Published: May 2007

A preparation of recombinant birch pollen allergen of Betula verrucosa isoform 1a (Bet v 1a) containing chemically modified (carbamylated) variants has been analyzed by CZE and CIEF. In CZE, employing a 100 mmol/L MES buffer at pH 6.50, with 0.4 mmol/L tetraethylenepentamine (TEPA) added, allowed for the resolution of 17 protein fractions. The CIEF profiling of the allergen preparation required a combination of a wide‐pH‐range carrier ampholyte (CA) of pH 3–10 with two narrow‐range CAs of pH 5–6 and 5–7. For CIEF, 91 mmol/L of glycine at pH 2.12 and 20 mmol/L of CHES at pH 10.00 were applied as anolyte and catholyte, respectively. The generated pH gradient was nonlinear with a flat slope for pH 4–6, thus providing an improved resolution. In CIEF, up to 18 protein fractions were distinguished as well. The pI of the target allergen Bet v 1a was 4.9 as determined by means of two pI marker compounds flanking the allergen. Relative purity of the target allergen within the preparation containing carbamylated variants was in accordance for both separation systems and varied between 40.7 and 42.8%.
Theory‐based evaluation: Reflections ten years on: Theory‐based evaluation: Past, present, and future
Authors: Rogers Patricia J. , Weiss Carol H.
Published: May 2007

This chapter highlights the continued salience of Weiss's questions about theory‐based evaluation, especially given the often simplistic uses of program theory in evaluation.

Theory‐based evaluation examines conditions of program implementation and mechanisms that mediate between processes and outcomes as a means to understand when and how programs work.
AEA and evaluation: 2006 (and beyond)
Authors: Mark Melvin M.
Published: May 2007

At the twentieth birthday of the American Evaluation Association, its twentieth‐year president looks back at the growth of the association and the field of evaluation, and identifies where AEA and evaluation might go in the future.
Functional cortical changes of the sensorimotor network are associated with clinical recovery in multiple sclerosis
Authors: Mezzapesa Domenico M. , Rocca Maria A. , Rodegher Mariaemma , Comi Giancarlo , Filippi Massimo
Published: May 2007

Objective:

To assess the early cortical changes following an acute motor relapse secondary to a pseudotumoral lesion in MS patients, the longitudinal cortical functional correlates of clinical recovery, and the evolution over time of cortical reorganization.

Methods:

FMRI during the performance of a simple motor task were obtained from 12 MS patients (after a clinical attack involving the motor system secondary to a pseudotumoral lesion) and 15 matched controls. In six patients and five controls, a longitudinal fMRI study was also performed.

Results:

In patients, at baseline, the primary sensorimotor cortex (SMC) of the ipsilateral (contralesional) hemisphere was significantly more active during task performance with the impaired than the unimpaired hand. During task performance with the unimpaired hand, the ipsilateral cerebellum and several motor areas in the contralateral hemisphere were significantly more active. Pseudotumoral lesion volume was correlated with activation of the primary SMC bilaterally (r = −0.86 and −0.85) and the nine‐hole peg test score with activation of the primary SMC of the affected hemisphere (r = 0.88). A recovery of function of the primary SMC of the affected hemisphere was found in the four patients with clinical improvement. In the two patients without clinical recovery, there was a persistent recruitment of the primary SMC of the unaffected hemisphere.

Conclusions:

Pseudotumoral MS lesions affecting the motor system can determine short‐term cortical changes characterized by the recruitment of pathways in the unaffected hemisphere. The regain of function of motor areas of the affected hemisphere seems to be a critical factor for a favorable recovery. Hum Brain Mapp 2008. © 2007 Wiley‐Liss, Inc.
OFT, VBP: QED?
Authors: Claxton Karl
Published: May 2007

The report by the Office of Fair Trading (OFT) on the UK pharmaceutical price regulation scheme (PPRS) recommends the reform of the current scheme, which is a combination of profit and price controls, to one where price is based on the health benefits offered by a pharmaceutical. On closer examination some of the more commonly expressed concerns about these proposals do not seem to be well founded.

In principle, the OFT's recommendations may contribute to allocative and dynamic efficiency in the NHS. However, there are some dangers and the details of how it will be implemented are crucial. For example, value‐based pricing with an inappropriate threshold for cost‐effectiveness, or an inappropriate pricing structure, could lead to technologies being adopted at prices where their benefits, in terms of health outcome, do not offset the health displaced elsewhere in the NHS, a situation in which the NHS is damaged rather than improved by innovation. A failure to account for uncertainty and the value of evidence in negotiating prices and coverage could also undermine the evidence base for future NHS practice. Whatever view is taken, the OFT report will inevitably shape the scope of future policy debates about value, guidance, price and innovation. Copyright © 2007 John Wiley & Sons, Ltd.
Population prevalence and symptom associations of autonomic dysfunction in primary biliary cirrhosis
Authors: Newton Julia L. , Hudson Mark , Tachtatzis Phaedra , Sutcliffe Kathryn , Pairman Jessie , Burt Jennifer A. , Jones David E. J.
Published: May 2007

Patients with primary biliary cirrhosis (PBC) frequently experience significant fatigue thought to result from as-yet-unidentified central nervous system (CNS)-mediated processes. Pilot studies have suggested that autonomic dysfunction is a frequent occurrence in PBC and may contribute to the pathogenesis of this fatigue. The degree to which autonomic dysfunction affects the PBC population as a whole, and its interrelationship with other symptoms experienced by PBC patients remains unstudied. In this study, we used a geographically defined, fully representative PBC patient cohort to study the prevalence of symptoms of autonomic dysfunction and its relationship with other symptoms of PBC. Symptoms of cardiovascular autonomic dysfunction (as assessed using the Orthostatic Grading Scale [OGS]) were significantly more frequently reported and significantly more severe in PBC patients than in both matched normal controls (40% versus 6% with moderate or worse orthostasis (

P

< .0001), mean OGS score 3.2 ± 3.4 versus 1.3 ± 1.9,

P

< .005) and in patients with primary sclerosing cholangitis and in severity were independently associated with severity of fatigue and cognitive symptoms (both

r

2 = 0.3,

P

< .0001). Thirteen of 20 patients with an OGS value > 4 (moderate severity and worse) had significant abnormality in autonomic regulation of blood pressure, which was identified on dynamic testing.

Conclusion:

Symptoms suggestive of autonomic dysfunction frequently occur in PBC patients and reflect dysregulation of actual blood pressure. Autonomic dysfunction is independently associated with both fatigue and, importantly, symptoms of cognitive dysfunction, suggesting the potential for significant organic sequelae. (Hepatology 2007;45:1496–1505.)
Hepatitis B x antigen up-regulates vascular endothelial growth factor receptor 3 in hepatocarcinogenesis
Authors: Lian Zhaorui , Liu Jie , Wu Mengchao , Wang Hong-Yang , Arbuthnot Patrick , Kew Michael , Feitelson Mark A.
Published: May 2007

Hepatitis B x antigen (HBxAg) is a

trans

-activating protein that contributes to liver cancer, in part, by altering the expression of cellular genes. However, few natural effectors of HBxAg have been identified. Hence, HBxAg positive and negative HepG2 cells were prepared and analyzed by PCR select cDNA subtraction. The results identified elevated vascular endothelial growth factor receptor-3 short form splice variant (VEGFR-3S) expression in HBxAg positive compared to negative cells. Normally, VEGFR-3 activates Akt signaling in lymphatic endothelial cells, resulting in lymphangiogenesis. In contrast, the results here show that the expression of VEGFR-3S is up-regulated in >75% of HBxAg positive hepatocellular carcinoma (HCC) nodules. VEGFR-3S up-regulation correlates with the expression of HBxAg, is associated with decreased survival in tumor bearing patients, and when over-expressed in HepG2 cells, strongly stimulated cell growth in culture, in soft agar, and accelerated tumor formation in a ligand independent manner. VEGFR-3S siRNA partially blocked the ability of HBxAg to promote hepatocellular growth. In conclusion, HBxAg may short circuit VEGFR-3S signaling in liver cancer. Blocking VEGFR-3S signaling may be effective in preventing tumor development and/or prolonging survival in tumor bearing patients. (Hepatology 2007;45:1390–1399.)
Composite suspended sediment particles in river systems: their incidence, dynamics and physical characteristics
Authors: Woodward J. C. , Walling D. E.
Published: May 2007

Most of the existing data on the effective particle size characteristics of fluvial suspended sediment derive from instantaneous sampling methods that may not be representative of the overall suspended sediment loads. This presents difficulties when there is a need to incorporate effective particle size data into numerical models of floodplain sedimentation and sediment‐associated contaminant transfer. We have used a field‐based water elutriation apparatus (WEA) to assemble a large (36 flood) database on the time‐integrated nature of the effective and absolute particle size characteristics of suspended sediment in four subcatchments of the River Exe basin of southwest England. These catchments encompass a wide range of terrains and fluvial environments that are broadly representative of much of the UK and temperate, low relief northwest Europe. The WEA provides important data on the physical characteristics of composite particles that are not attainable using other methods. This dataset has allowed, for the first time, detailed interbasin comparisons of the time‐integrated particle size characteristics of suspended sediment and reliable estimates of the contribution of five effective size classes to the mean annual suspended sediment load of the study catchments. The suspended sediment load of each river is dominated by composite rather than primary particles, with, for example, almost 60% (by mass) of the sediment load of the River Exe at Thorverton transported as composite particles > 16 µm in size. All the effective size classes contain significant clay components. A key outcome of this study is the recognition that each catchment has a distinctive time‐integrated effective particle size signature. In addition, the time‐integrated effective particle size characteristics of the suspended loads in each of the catchments display much greater spatial variability than the equivalent absolute particle size distributions. This indicates that the processes producing composite particles vary significantly between these catchments, and this has important implications for our understanding of the dynamics of suspended sediment properties. Copyright © 2007 John Wiley & Sons, Ltd.
Computability of Minimizers and Separating Hyperplanes
Authors: Wong Kam‐Chau
Published: May 2007

We prove in recursive analysis an existence theorem for computable minimizers of convex computable continuous real‐valued functions, and a computable separation theorem for convex sets in ℝm.

Mathematics Subject Classification: 03F60, 52A40.
On a Question of Phillips
Authors: Gencer Çiǧdem , Terziler Mehmet
Published: May 2007

In [5] Phillips proved that one can obtain the additive group of any nonstandard model *ℤ of the ring ℤ of integers by using a linear mod 1 function h : F ℚ, where F is the α‐dimensional vector space over ℚ when α is the cardinality of *ℤ. In this connection it arises the question whether there are linear mod 1 functions which are neither addition nor quasi‐linear. We prove that this is the case.
Order‐free Recursion on the Real Numbers
Authors: Brattka Vasco
Published: May 2007

We investigate operations, computable in the sense of Recursive Analysis, which can be generated recursively from the arithmetic operations and the limit operation without using any tests on the real numbers. These functions, called order‐free recursive, can be shown to include a large class of computable functions. As main tools we provide an effective version of the Stone‐Weierstraß Approximation Theorem, as well as recursive partitions of unity.
On Nondeterminism, Enumeration Reducibility and Polynomial Bounds
Authors: Copestake Kate
Published: May 2007

Enumeration reducibility is a notion of relative computability between sets of natural numbers where only positive information about the sets is used or produced. Extending e‐reducibility to partial functions characterises relative computability between partial functions. We define a polynomial time enumeration reducibility that retains the character of enumeration reducibility and show that it is equivalent to conjunctive non‐deterministic polynomial time reducibility. We define the polynomial time e‐degrees as the equivalence classes under this reducibility and investigate their structure on the recursive sets, showing in particular that the pe‐degrees of the computable sets are dense and do not form a lattice, but that minimal pairs exist. We define a jump operator and use it to produce a characterisation of the polynomial hierarchy.
On Interstices of Countable Arithmetically Saturated Models of Peano Arithmetic
Authors: Bamber Nicholas , Kotlarski Henryk
Published: May 2007

We give some information about the action of Aut(M) on M(0), where M is a countable arithmetically saturated model of Peano Arithmetic. We concentrate on analogues of moving gaps and covering gaps inside M(0).
Arithmetical Measure
Authors: Terwijn Sebastiaan A. , Torenvliet Leen
Published: May 2007

We develop arithmetical measure theory along the lines of Lutz [10]. This yields the same notion of measure 0 set as considered before by Martin‐Löf, Schnorr, and others. We prove that the class of sets constructible by r.e.‐constructors, a direct analogue of the classes Lutz devised his resource bounded measures for in [10], is not equal to RE, the class of r.e. sets, and we locate this class exactly in terms of the common recursion‐theoretic reducibilities below K. We note that the class of sets that bounded truth‐table reduce to K has r.e.‐measure 0, and show that this cannot be improved to truth‐table. For Δ2‐measure the borderline between measure zero and measure nonzero lies between weak truth‐table reducibility and Turing reducibility to K. It follows that there exists a Martin‐Löf random set that is tt‐reducible to K, and that no such set is btt‐reducible to K. In fact, by a result of Kautz, a much more general result holds.
Elementary Properties of the Finite Ranks
Authors: Dawar Anuj , Doets Kees , Lindell Steven , Weinstein Scott
Published: May 2007

This note investigates the class of finite initial segments of the cumulative hierarchy of pure sets. We show that this class is first‐order definable over the class of finite directed graphs and that this class admits a first‐order definable global linear order. We apply this last result to show that FO(<, BIT) = FO(BIT).
Microwave‐Assisted Synthesis of Associative Hydrogels
Authors: Kretschmann Oliver , Schmitz Sarah , Ritter Helmut
Published: May 2007

In the present paper, the microwave (MW)‐assisted synthesis of hydrogel forming polymers based on poly(acrylic acid) (1) is described. The polymer analogous condensation reaction between adamantyl moieties bearing free amino groups and poly(acrylic acid) (1) was carried out simply by mixing both components and subsequent use of MW protocol. The mixture was irradiated for 20 min without the addition of solvents or coupling agents. Aqueous solutions of the sodium salts of the obtained hydrophobically modified poly(acrylic acid)s showed a very high viscosity due to the intermolecular association of the hydrophobic side chains and the resulting formation of physical networks. By the addition of randomly methylated β‐cyclodextrin (RAMEB), the rheology of these systems could be influenced significantly.

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Mechanism of the formation of singularities for quasilinear hyperbolic systems with linearly degenerate characteristic fields
Authors: Li Ta‐Tsien , Peng Yue‐Jun , Yang Yong‐Fu , Zhou Yi
Published: May 2007

One often believes that there is no shock formation for the Cauchy problem of quasilinear hyperbolic systems (of conservation laws) with linearly degenerate characteristic fields. It has been a conjecture for a long time (see Arch. Rational Mech. Anal. 2004; 172:65–91; Compressible Fluid Flow and Systems of Conservation Laws in Several Space Variables. Springer: New York, 1984) and it is still an open problem in the general situation up to now. In this paper, a framework to justify this conjecture is proposed, and, by means of the concept such as the
strict block hyperbolicity, the part richness and the successively block‐closed system, some general kinds of quasilinear hyperbolic systems, which verify the conjecture, are given. Copyright © 2007 John Wiley & Sons, Ltd.
Defect investigation of stacked self‐assembled InAs/GaAs quantum dot lasers
Authors: Ng J. , Bangert U. , Missous M.
Published: May 2007

Two classes of stacked structures with (i) varying InAs nominal thickness θ but fixed GaAs “spacer” layer (d = 25 nm), and ii) a varying d but fixed InAs nominal thickness (θ = 2.73 monolayers (ML)) were grown by solid‐source molecular beam epitaxy (MBE). The formation of large ‘volcano‐like' defects with stacking faults and dislocations, penetrating several layers into the stack, was observed for a nominal InAs deposition of 2.73 ML and 3.62 ML in case (i). In case (ii), with, d = 50 nm, a dramatic improvement in structural integrity was observed with the absence of the ‘volcano‐like’ defect. The Photoluminescence (PL) intensity where, d = 50 nm, was almost 132 times stronger for, θ = 3.64 ML, indicating that the improvement in crystal structure resulted in better PL efficiencies. Remarkably, significant improvements in PL intensity were observed when the material was etched to selectively remove the topmost stacks thus demonstrating that the ‘volcano‐like’ defects were responsible for the severely suppressed PL efficiencies. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum confinement effect in nanohills formed on a surface of Ge by laser radiation
Authors: Medvid Artur , Dmytruk Igor , Onufrijevs Pavels , Pundyk Iryna
Published: May 2007

Photoluminescence in visible range of spectra from nanohills formed on a surface of Ge single crystal by JAG:Nd laser radiation was found. This photoluminescence is explained by quantum confinement effect in quantum dots on a top of nanohills. Red shift of 300 cm–1 line micro‐Raman back scattering spectrum is an evidence of this suggestion. The calculation of QDs diameter using band gap shift photoluminescence spectra and peak frequency in micro‐Raman spectra as a function of diameter for spherical Ge particles gives diameters of nano‐balls on the top of nanohills is 4 nm and 6 nm. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sources of misfit dislocations in ZnSe/GaAs (001) heterostructures
Authors: Lavagne S. , Levade C. , Vanderschaeve G.
Published: May 2007

Strain relaxation in low‐mismatch ZnSe/GaAs heterostructures is studied by transmission electron microscopy. The early stages of plastic relaxation proceeds by activation of secondary 1/2〈011〉{133}slip systems, leaving an array of misfit dislocations aligned along 〈310〉 directions in the interface. Threading dislocations originate from randomly distributed, highly strained single‐or multi‐twinned regions in the ZnSe layer, that are probably due to growth accidents. The influence of cross slip on the propagation of threading dislocations is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Global benefit–risk assessment in designing clinical trials and some statistical considerations of the method
Authors: Pritchett Yili Lu , Tamura Roy
Published: May 2007

When characterizing a therapy, the efficacy and the safety are two major aspects under consideration. In prescribing a therapy to a patient, a clinician puts the two aspects together and makes a decision based on a consolidated thought process. The global benefit–risk (GBR) measures proposed by Chuang‐Stein et al. (Stat. Med. 1991; 10:1349–1359) are useful in facilitating the thinking, and creating the framework for making statistical comparisons based on benefit–risk point of view. This article describes how a GBR linear score was defined and used as the primary outcome measure in a clinical trial design. The robustness of the definitions of ‘benefit’ and ‘risk’ are evaluated using different criteria. The sensitivity of the pre‐specified weights is also analyzed using alternative weights; one of those was determined by the relative to an identified distribution integral transformation approach (Biometrics 1958; 14:18–38). Statistical considerations are illustrated using pooled data from clinical trials studying antidepressant. The pros and cons for using GBR assessments in the setting of clinical trials are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Density functional study of protonation of deoxynucleosides: Electrophilic active sites and proton affinities
Authors: Xia Fei , Xie Hujun , Cao Zexing
Published: May 2007

Possible low‐energy tautomers and their interconversions, electrophilic active sites, and proton affinities of deoxyribonucleosides have been studied by the density functional theory. The calculated results indicate that the protonation features of deoxyribonucleosides are less changed as compared with their corresponding bases. Proton affinities of 2′‐deoxyriboguanosine (dG), 2′‐deoxyribocytidine (dC), 2′‐deoxyriboadenosine (dA), and 2′‐deoxyribothymidine (dT) at the most favored sites are 240.6 kcal mol−1 (N7), 238.5 kcal mol−1 (N3), 233.4 kcal mol−1 (N1), and 217.9 kcal mol−1 (O4), respectively. Predicted tautomerization barriers are substantially high and exclude the coexistence possibility of their low‐energy tautomers at room temperatures. Calculations show good agreement with experiments and provide a basis for description of structures and energetics of neutral and protonated deoxyribonucleosides. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Polymer Grafting from CdS Quantum Dots via AGET ATRP in Miniemulsion
Authors: Esteves Ana C. C. , Bombalski Lindsay , Trindade Tito , Matyjaszewski Krzysztof , Barros‐Timmons Ana
Published: May 2007

We report the synthesis of CdS quantum dot (QD)–poly(acrylate) nanocomposites using a recently developed catalytic system where activators are generated by electron transfer for atom‐transfer radical polymerization (ATRP) in a miniemulsion. The QD surface was functionalized with a tris(alkyl)phosphine, previously modified with an ATRP chlorine initiator, and subsequent controlled polymerization was carried out from the functionalized surface of nanoparticles. The final material showed a high homogeneity and the QDs were evenly dispersed. The optical‐absorption edge in the visible spectra of the nanocomposites attests the presence of the CdS QDs. Quantum confinement effects were assigned, though a blue shift in relation to the optical spectrum of the initial QDs has been observed.
Zur Stabilität der elastischen Schalen I
Authors: Deuker Ernst‐August
Published: May 2007

In der vorliegenden Arbeit werden die untersuchungen über endliche Verformungen eines Kontinuums und die aus ihnen abzuleitenden Stabilitätskriterien des elastischen Gleichgewichts,wie ich sie an anderer Stelle[3] für den allgemeinen Dreidimensionalen Körper Angestellt habe, auf dünne elastische Schalen übertragen. Es werden deshalb Zunächst die Grundgleichungen der Schalentheorie fü endliche Verformungen entwickelt, als notwendige Grundlage für Stabilitätsuntersuchungen. Die Heranziehung der Methoden und Ergebnisse der Differentialgeometrie, insbesondere die konsequente Anwendung der Tensorrechnung, ermöglicht nicht nur, allgemeine Formeln von großer Durchsichtigkeit zu entwickeln, sondern erleichtert auch die Behandlung spezieller Probleme. In dieser Arbeit wird das an dem Beispiel der Kreiszylinderschale, in einer weiteren an dem der Kugelschale gezeigt werden.
Wärmeausgleichsvorgänge in bestrahlten Platten
Authors: Ludwig Konrad
Published: May 2007

Die Wärmeausgleichsvorgänge in einer einseitig bestrahlten Platte, deren konstante Anfangstemperatur die der Umgebung ist, werden untersucht. Dabei wird außer der eingestrahlten auch die durch diese Begrenzungsebene ausgestrahlte Wärme berücksichtigt. Die Lösung wird sowohl durch Produktansatz, wie nach der Operatorenmethode gewonnen. Als Beispiel berechnet Verfasser zahlenmäßig für ein Silber‐ und für ein Wismutplättchen mit und ohne Wärmeabgabe der nicht bestrahlten Begrenzungsebene die Temperatur der bestrahlten Begrenzungsebene und die Differenz der Temperaturen der beiden Begrenzungsebenen als Funktionen der Zeit.
Über die Teststärke des Fisherschen Testes
Authors: Richter Hans
Published: May 2007

Bei festen Marginalien einer 2×2‐Tafel, die das Ergebnis der Anwendung zweier Bearbeitungsverfahren widerspiegelt, und bei Vorgabe einer Signifikanzschranke α für die Anwendung des Fisherschen Testes ist die Teststärke P« allein abhängig von einem Parameter ξ, der die Überlegenheit des neuen Bearbeitungsverfahrens über das alte charakterisiert. Der Test besitzt einen zu α gehörigen Unempfindlichkeits‐ξ‐Bereich 0 ≤ ξ ≤ ξ0 Für Pξ und ξ0 werden Formeln abgeleitet, die für große Werte der Marginalien einfache Approximationen gestatten. Jedoch ist auch für kleine Werte der Marginalien die Approximation für ξ0 noch ausreichend.
Physical and chemical characteristics of butterfat fractions obtained by crystallization from molten fat
Authors: Amer M. A. , Kupranycz D. B. , Baker B. E.
Published: May 2007

Both summer and winter butterfats were fractionated using a laboratory procedure which was designed to simulate a commercial fractionation process. The process is based on a slow, controlled cooling of the melted fat, a short stabilization time at the fractionation temperature, and separation of the crystals from the liquid oil by vacuum filtration using a stainless steel perforated disc. Fractionation temperatures of 29, 26, 23 and 19 C for winter butterfat and 29 and 19 C for summer butterfat were used to obtain solid and liquid fractions at each temperature. Three replications at each temperature showed good reproducibility of results. The fractions were characterized by their fatty acid and triglyceride compositions, melting and crystallization behavior, iodine value, peroxide value and melting point.
Sunflower oil diesel fuel: Engine wear implications
Authors: Rewolinski C. , Shaffer D. L.
Published: May 2007

Diesel lubricating oil contaminated with sunflower oil fuel was degraded under conditions simulating an engine crankcase environment for metal wear testing. Wear analyses were performed using a fourball apparatus according to ASTM D 4172. Lubricity of oils was characterized by ball scar dimensions. Contaminated lubricating oils exhibited lower metal wear indexes than pure lube oil control samples, even when the former were severely degraded as measured by thickening and loss of alkaline reserve.
2‐trans,4‐cis,7‐cis‐Decatrienal, the fishy off‐flavor occurring in strongly autoxidized oils containing linolenic acid or ω 3,6,9, etc., fatty acids
Authors: Meijboom P. W. , Stroink J. B. A.
Published: May 2007

A possible decomposition product of oils containing unsaturated fatty acids with the double bond pattern ω3,6,9 or ω3,6,9, etc., is 2‐trans,4‐cis,7‐cis‐decatrienal. It has therefore been investigated whether this trienal is present in strongly autoxidized linolenic acid, soybean, linseed and fish oils. Via a degassing technique the carbonyls from the samples of oils heated in a closed system under nitrogen were collected and separated as their 2,4‐dinitrophenylhydrazones (DNPHs) by thin layer chromatography (TLC). The presence of 2‐trans,4‐cis,7‐cis‐decatrienal in the samples was positively established by TLC, UV absorption and mass spectroscopy of its DNPH. All analytical data established the complete identity of the isolated DNPH with a synthesized 2,4,7‐decatrienal‐DNPH. The free aldehyde obtained on hydrolysis of the alkatrienal‐DNPH in question had the same flavor as authentic 2‐trans,4‐cis,7‐cis‐decatrienal, having a fish or rather a whale oil flavor.
Direct esterification of sodiumcis‐9,10‐epiminooctadecanoate
Authors: Bilyk A. , Eisner A. , Maerker G.
Published: May 2007

Compounds containing the aziridine ring are known to have a tendency toward polymerization in the presence of mineral acids. Moreover, with aziridine derivatives of fatty acids, ring opening reactions are possible as a result of nucleophilic attack by generated carboxylic acids groups. It was found that high yields (86–89%) of methylcis‐9,10‐epiminooctadecanoate, with a minimum of attendant byproducts could be obtained by heating the corresponding sodium soap with methanol in the presence of certain acid catalysts under carefully controlled conditions. Temperature, duration of the heating period, and catalyst concentration were the variables studied for each catalyst. The catalysts evaluated were: boron trifluoride etherate, methanesulfonic acid, sulfuric acid, fluoboric acid andp‐toluenesulfonic acid. Of these, for most laboratory preparations,p‐toluenesulfonic acid is the catalyst of choice.
Laundry soil‐suspending activity of certain microbial polysaccharides
Authors: Jeanes Allene , Bistline R. G. , Stirton A. J.
Published: May 2007

Certain extracellular microbial anionic heteropoly‐saccharides and phosphorylated mannans suspend laundry soil comparably with carboxymethyl cellulose. These biodegradable biopolymers have other properties compatible with components commonly used in detergent formulations.
XRecent advances in canola oil hydrogenations
Authors: Koseoglu S. S. , Lusas E. W.
Published: May 2007

Rapeseed oil has been the source of edible oils in many parts of the world. In the last decade, Canadian plant breeders have developed new rapeseed cultivars which yield oil low in erucic acid and meal low in glucosinolates. These cultivars were named “canola” by the Canadian rapeseed industry. Literature on the hydrogenation characteristics of canola oil is limited; however, in recent years, several aspects of canola oil hydrogenations with commercial nickel catalysts have been reported including the formation ofrans‐isomers, trisaturated glycerides and physical properties. In addition, as the methods for determination of sulfur compounds in canola oil developed, the effect of some isothiocyanates on the hydrogenation rate was further investigated to determine the relative catalyst poisoning ability of serveral of these sulfur compounds. However, during the last few years, most of the efforts were directed towards development of novel, selective and active catalysts for canola oil hydrogenations. These studies cover a wide range of homogeneous and heterogeneous catalysts including sulfur poisoned nickel, gold supported on silica, arene‐Cr(CO)3, RuCl2(CO)2(PPh3)2, palladium on carbon, palladium black and nickel and arene‐Cr(CO)3mixtures. Effects of temperature, pressure, catalyst concentration and catalyst preparation procedure on the hydrogenation rate, selectivity, catalyst life and quality of the oil were examined and compared with that of commercial nickel catalysts. A brief discussion about continous hydrogenations of canola oil with commerical fixed bed catalysts is also included.
Test procedure for evaluation of catalysts for nitrile reduction
Authors: Friedli F. E. , Gilbert R. M.
Published: May 2007

A procedure was developed that examines the effectiveness of nickel catalysts for the hydrogenation of fatty nitriles to amines. Rates of reaction, selectivity, and olefinic reduction were the parameters studied. The procedure can be used for new catalyst screening and is ideally suited for quality assurance testing of production catalysts. It involves the reduction of nitriles to amines at 410°F (210°C) and 500 psig using a .2% Ni loading level. A mixture of primary and secondary amines is obtained which is characteristic of the catalyst’s selectivity. Both sponge and supported nickel catalysts were tested using tallow nitriles as the feedstock.
The rhodium‐catalyzed deuteration of unsaturated triglycerides
Authors: Adlof R. O.
Published: May 2007

Tripalmitolein, triolein, trilinolein and trilinolenin were deuterated with deuterium gas and Wilkinson’s catalyst [(Ph3P)3RhCl(I)]. Recrystallization of the products from acetone yielded highly pure deuterium‐labelled triglycerides (TG). The deuterated TG were converted to methyl esters and analyzed by gas chromatography/mass spectroscopy to determine the deuterium distribution. Methyl palmitate‐9,10‐d2 (from tripalmitolein) and methyl stearate‐9,10‐d2 (from triolein) yielded isotopic distributions of 93–97% d2, methyl stearate‐9,10,12,13‐d4 (from trilinolein) of 74% d4 and methyl stearate‐9,10,12,13,15,16‐d6 (from trilinolenin) of only 58% d6. Because the deuterium‐labelled TG were to be used in human metabolism studies, atomic absorption spectroscopy was used to determine if any residual rhodium was present. No rhodium was detected at 70 ppb (the minimum detection limit).
Utilization of rice bran oil to produce an antifoamer
Authors: El‐Zanati E. M. , Zaher F. A.
Published: May 2007

Crude rice bran oil was dewaxed by chilling to 17°C, followed by centrifuging. The wax sludge obtained was 68% free fatty acids and 32% waxes, whereas the oil phase was 65.65% fatty acids and 34.35% glycerides. The dewaxed oil was evaluated as an antifoaming agent for aqueous media and compared to commercial oleic acid. It was thought that dewaxed rice bran oil has an antifoaming power greater than oleic acid, especially when used in small proportions.

Dewaxed rice bran oil was also applied to break and control the foam formation in a phosphoric acid production unit.