bluuebunny/crossref_metadata_2025 huggingface dataset:
Palladium‐Catalyzed Preparation of Propargylic or Allenylic Sulfides from Propargyl Halides or Mesylate and Thiols
Authors: Tsutsumi Ken , Fujimoto Kouji , Yabukami Tomomi , Kawase Tomohiro , Morimoto Tsumoru , Kakiuchi Kiyomi
Published: January 2004

In the presence of a catalytic amount of Pd0‐dppe complex [dppe: 1,2‐bis(diphenylphosphanyl)ethane], generated in situ from [Pd2(dba)3·CHCl3] and dppe, propargylic bromide 1a reacted with an equimolar amount of propanethiol at 60 °C in DMF to afford propargylic sulfide 2 in an excellent yield. The reaction occurs readily when carried out in the presence of the weak base triethylamine. The choice of both the phosphane, which is employed as the palladium atom’s ligand, and the solvent have a remarkable effect on this reaction. We found that the optimum conditions for the reaction are those using a bidentate phosphane ligand (dppe) in a polar solvent (DMF). Compound 1a reacted smoothly with both aromatic (PhSH) and secondary thiols (CySH) in high yields. The reactions with thiols bearing functional groups (OH or Cl) proceeded selectively in good to moderate yields. Primary chlorides 1b−e were readily converted into their corresponding propargylic sulfides 7−10 in high yields. The Pd0‐dppe catalyst was ineffective in the reaction of the bromide 1g bearing a tBu group at the propargylic position, but the reaction of the corresponding mesylate 1h using the Pd0‐DIOP catalyst [DIOP = O‐isopropylidene‐2,3‐dihydroxy‐1,4‐bis(diphenylphosphanyl)butane] at 100 °C afforded the product 11 in good yield. Allenylic sulfides were obtained from 1g−i. We suggest that a cationic η3‐type complex may be a more reactive intermediate in this catalytic reaction than neutral η1‐ or η3‐allenyl/propargylpalladium complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Room Temperature Nematic Photoswitchable Liquid Crystals — Molecular Modularisation of Functional Elements
Authors: Frigoli Michel , Mehl Georg H.
Published: January 2004

The successful design of photochromic self‐assembly systems requires understanding (on both the molecular and sub‐molecular scales) of diverse and often competing structure‐property relationships. Such molecular systems are promising as components for photonically switchable components in opto‐electronic devices. Molecular modularisation can be an efficient approach to obtain such materials. The design, synthesis and the photochromic and mesomorphic properties of stable photochromic systems which exhibit nematic LC phase behaviour at room temperature are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of 11C‐/13C‐Ketones by Suzuki Coupling
Authors: Rahman Obaidur , Kihlberg Tor , Långström Bengt
Published: January 2004

Aryl triflates, methyl‐ or arylboronic acids, and a low concentration of [11C]carbon monoxide were employed on small scale in the syntheses of fifteen 11C‐labelled ketones using palladium‐mediated Suzuki coupling reactions. The reagents were confined in a micro‐autoclave and heated at 150 °C for 5 min. The reaction required the presence of LiBr, but no additional base. The 11C‐labelled products were obtained with decay‐corrected radiochemical yields in the range 10−70% and with high specific radioactivity (150−640 GBq/μmol). The radiochemical purity of the final products exceeded 98%. One 13C‐substituted ketone ([13C]‐2′‐benzonaphthone) was prepared and analysed by NMR spectroscopy for confirmation of the labelling position. The reference compound 2′‐benzonaphthone was prepared by a palladium‐catalysed reaction between sodium tetraphenylborate and 2‐naphthoyl chloride. 2‐Thienyl p‐tolyl ketone, 4‐nitrophenyl 2‐thienyl ketone and 2‐naphthyl 2‐thienyl ketone were prepared by reactions between thiophene‐2‐boronic acid and the corresponding acid chlorides. The presented approach is novel and seems to be an efficient method for the synthesis of a wide range of 11C‐ as well as 13C‐labelled ketones. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Tuscolid and Tuscoron A and B: Isolation, Structural Elucidation and Studies on the Biosynthesis of Novel Furan‐3(2H)‐one‐Containing Metabolites from the Myxobacterium Sorangium Cellulosum
Authors: Niggemann Jutta , Herrmann Martina , Gerth Klaus , Irschik Herbert , Reichenbach Hans , Höfle Gerhard
Published: January 2004

Three novel metabolites, tuscolid (1) and tuscoron A (2) and B (3), were isolated from the myxobacterium Sorangium cellulosum (strains So ce1401 and So ce1383). The structures were elucidated by detailed NMR spectroscopic analysis, and their biosynthesis was studied by feeding 13C‐labelled precursors. The results revealed that the macrolide 1 and the acyclic derivative 2 are closely related polyketides containing, as a characteristic structural feature, a furan‐3(2H)‐one ring system. The related minor component tuscoron B (3) was identified as an unstable structural analogue of tuscoron A. The relative stereochemistry of the tetrahydropyran ring and of C‐13 to C‐17 of tuscolid (1), and of the dihydropyran ring of tuscoron A (2), was determined on the basis of 1H‐1H‐coupling constants and NOE correlations. A tentative mechanism for the conversion of 1 into 2 is discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
3‐Aminobicyclo[1.1.1]pentane‐1‐carboxylic Acid Derivatives: Synthesis and Incorporation into Peptides
Authors: Pätzel Michael , Sanktjohanser Maximilian , Doss Alexander , Henklein Peter , Szeimies Günter
Published: January 2004

We have developed an efficient synthesis of derivatives of 3‐aminobicyclo[1.1.1]pentane‐1‐carboxylic acid (7, 8, 9, and 10) starting from [1.1.1]propellane (3). These rigid analogues of γ‐aminobutyric acid have been incorporated into linear and cyclic peptides using solution chemistry and solid‐phase techniques. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Green Protocol for the Biginelli Three‐Component Reaction: Ag3PW12O40 as a Novel, Water‐Tolerant Heteropolyacid for the Synthesis of 3,4‐Dihydropyrimidinones
Authors: Yadav Jhillu S. , Reddy Basi V. Subba , Sridhar Pamu , Reddy Joolakanti S. S. , Nagaiah Kommu , Lingaiah Nakka , Saiprasad Potharaja S.
Published: January 2004

Biginelli three‐component condensation of an aldehyde, β‐keto ester, and urea proceeds smoothly on the surface of the silver salt of heteropolyacid (HPA), i.e. Ag3PW12O40, in water to afford the corresponding 3,4‐dihydropyrimidinones in high‐to‐quantitative yields under mild conditions. The heterogeneous solid acid provides ease of separation of the catalyst and isolation of the products. The recovered catalyst can be recycled in subsequent reactions with consistent activity. Compared to the classical Biginelli reaction conditions, this new method has the advantages of improved yields, reusability of the catalyst, an eco‐friendly solvent, ease of isolation of products, and simplicity in the experimental procedure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Enantioselective 1,3‐Dipolar Cycloadditions of Unsaturated Aldehydes Promoted by A Poly(ethylene glycol)‐Supported Organic Catalyst
Authors: Puglisi Alessandra , Benaglia Maurizio , Cinquini Mauro , Cozzi Franco , Celentano Giuseppe
Published: January 2004

We have developed a polymer‐supported version of MacMillan’s catalyst by anchoring a tyrosine‐derived imidazolidin‐4‐one by means of a spacer to the monomethyl ether of poly(ethylene glycol) (MW = 5000 Da). The supported organic catalyst was employed in some 1,3‐dipolar cycloadditions involving α,β‐unsaturated aldehydes and nitrones. The products were obtained in enantiomeric excesses very similar to those observed with the non‐supported catalyst, but the chemical yields were somewhat lower. Exploiting the solubility profile of the polymeric support, the catalyst was readily separated from the reaction products, recovered, and recycled. Catalyst recycling was accompanied by a very marginal erosion (if any) of the enantioselectivity and a more‐substantial decrease in chemical efficiency. We ascribe the latter phenomenon mainly to the intrinsic instability of the catalyst under the reaction conditions, which is, however, a common feature of both the non‐supported and supported catalysts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Formal Total Synthesis of (±)‐1,13‐Herbertenediol
Authors: Srikrishna Adusuhilli , Rao M. Srinivasa
Published: January 2004

A formal total synthesis of (±)‐1,13‐herbertenediol, employing a ring‐closing metathesis reaction of the 4‐arylhepta‐1,6‐diene‐4‐carboxylate 15 as the key reaction, is described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Palladium‐Catalyzed Telomerization of Butadiene with Tri‐O‐acetylated Pentoses as a Convenient Route to 2,7‐Octadienyl Glycosides
Authors: Hénin Françoise , Bessmertnykh Alla , Serra‐Muns Anna , Muzart Jacques , Baillia Henri
Published: January 2004

Palladium‐catalyzed telomerization of butadiene withO‐acetylated pyranoses having a free anomeric hydroxyl group was applied for synthesis of octadienyl glycosides. The ratio of linear to branched glycosides depends dramatically on the conditions used. By careful optimization of reaction parameters the highly selective formation (95:5) of linear glycosides was achieved. An extended mechanism of the telomerization reaction is proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis, Characterization, and Reaction of Crystalline Fischer’s Glucopyranosyl Isocyanate
Authors: Ichikawa Yoshiyasu , Matsukawa Yohei , Nishiyama Taihei , Isobe Minoru
Published: January 2004

We have established a simple method for the preparation of crystalline Fischer’s glucopyranosyl isocyanate 1. NMR spectroscopic analysis of 1 allowed the unambiguous determination of the stereochemistry at the anomeric position. Synthetic applications of glucopyranosyl isocyanate 1 were examined by its reactions with amines and alcohols to furnish a wide variety of neoglycoconjugates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Experimental assessment of electromigration properties of background electrolytes in capillary zone electrophoresis
Authors: Boušková Eva , Presutti Carla , Gebauer Petr , Fanali Salvatore , Beckers Jozef L. , Boček Petr
Published: January 2004

Electromigration dispersion (EMD) properties of background electrolytes (BGEs) used in capillary zone electrophoresis (CZE) are of key importance for the success of an analysis. The knowledge of these properties may serve well for the prediction of the asymmetry of peaks of analytes, for the prediction of unsafe regions where a strong interference of system zones may be expected, and for the selection of optimum conditions where the analytes of interest may give sharp and practically symmetric peaks. Present theories enable one to calculate and predict EMD properties of many BGEs but there is also a lot of BGEs that are beyond the present theoretical models as far as their composition and equilibria involved are considered. This contribution brings a method for assessment of EMD properties of any BGE from easily accessible experimental data. The method proposed is illustrated by model examples both for cationic and anionic separations. Imidazole acetate, histamine acetate, and histidine acetate served as model BGEs for cationic separations; as the model BGE for anionic separations, Tris‐borate and sodium‐borate BGEs have been selected since these buffers are frequently used and borate is well‐known for its complexing equilibria in aqueous solutions.
Nafion membrane electrophoresis with direct and simplified end‐column pulse electrochemical detection of amino acids
Authors: Fang Cheng , Wu Bingliang , Zhou Xingyao
Published: January 2004

A novel electrophoresis technique, in which the separation column was replaced by a strip of Nafion membrane (5.0 cm×0.20 mm×0.25 mm), was developed for the separation of an amino acid mixture (glycine, asparic acid and lysine), followed by quadruple‐pulse electrochemical detection. Nafion membrane contains hydrophilic pores (10–20 Å and 50–60 Å in size) acting as very narrow electrophoresis channels. The fixed‐charge sites (‐SO3−) on the hydrophilic pore surface provide a strong charged background. A platinum disk electrode (0.90 mm inner diameter) was employed as the detection electrode and the electrophoresis cathode was used as the quasi‐reference and counter electrode for the end‐column electrochemical detector, without decoupler. Under optimized conditions the mixture of amino acids could be separated at a voltage of only 90 V with a detection limit of 10−7 M, indicating that Nafion membrane electrophoresis is a potentially attractive technique for the separation of small organic molecules or ions.
Sample introduction techniques for microfabricated separation devices
Authors: Roddy Elizabeth S. , Xu Hongwei , Ewing Andrew G.
Published: January 2004

A great deal of progress has been made toward the development of the micro total analysis system (μ‐TAS) since its inception in 1990. A wide variety of applications, including genomics, proteomics and drug discovery, have prompted the development of analytical methods capable of very high throughput while maintaining low cost. The μ‐TAS concept addresses both of these requirements. Electrophoresis has been a key element in the development of the μ‐TAS. Most chemical and biochemical assays utilize a separation component at some point during analysis. Genomics, in particular, depends almost exclusively on electrophoresis for size‐based separations of DNA. This review examines sample introduction into microfabricated electrophoretic devices, or chips, primarily for DNA analysis. Sample introduction is an important component of these systems and is an essential process for making chip electrophoresis a widely applicable analytical technique. Specific issues, such as automation, the delivery of large numbers of samples to microfabricated devices and injection of picoliter‐sized sample plugs into a separation lanes on chips, are presented.
Fluid mechanics of electroosmotic flow and its effect on band broadening in capillary electrophoresis
Authors: Ghosal Sandip
Published: January 2004

Electroosmotic flow (EOF) usually accompanies electrophoretic migration of charged species in capillary electrophoresis unless special precautions are taken to supress it. The presence of the EOF provides certain advantages in separations. It is an alternative to mechanical pumps, which are inefficient and difficult to build at small scales, for transporting reagents and analytes on microfluidic chips. The downside is that any imperfection that distorts the EOF profile reduces the separation efficiency. In this paper, the basic facts about EOF are reviewed from the perspective of fluid mechanics and its effect on separations in free solution capillary zone electrophoresis is discussed in the light of recent advances.
Determination of the cis‐trans isomerization barrier of enalaprilat by dynamic capillary electrophoresis and computer simulation
Authors: Trapp Oliver , Trapp Gabriele , Schurig Volker
Published: January 2004

Dynamic capillary electrophoresis (DCE) and computer simulation of the elution profiles with the stochastic model has been applied to determine the isomerization barriers of the angiotensin converting enzyme inhibitor enalaprilat. The separation of the rotational cis‐trans isomeric drug has been performed in an aqueous 20 mM borate buffer at pH 9.3. Interconversion profiles featuring plateau formation and peak broadening were observed. To evaluate the rate constants kcis→trans and ktrans→cis of the cis‐trans isomerization from the experimental electropherograms obtained by dynamic capillary electrophoresis, elution profiles were analyzed by a simulation with iterative convergence to the experimental data using the ChromWin software which requires the total migration times of the individual isomers tR, the electroosmotic break‐through time t0, the plateau height hplateau, the peak widths at half height of the individual isomers wh, as well as the peak ratio of the isomers as experimental data input. From temperature‐dependent measurements between 0° and 15°C the thermodynamic parameters ΔG, ΔH and ΔS, the rate constants kcis→trans and ktrans→cis and the kinetic activation parameters ΔG≠, ΔH≠, and ΔS≠ of the cis‐trans isomerization of enalaprilat were obtained. From the activation parameters the isomerization barriers at 37°C were calculated to be ΔG≠trans→cis = 87.2 kJ·mol−1 and ΔG≠cis→trans = 91.9 kJ·mol−1.
Effect of Joule heating on efficiency and performance for microchip‐based and capillary‐based electrophoretic separation systems: A closer look
Authors: Petersen Nickolaj J. , Nikolajsen Rikke P. H. , Mogensen Klaus B. , Kutter Jörg P.
Published: January 2004

An attempt is made to revisit the main theoretical considerations concerning temperature effects (“Joule heating”) in electro‐driven separation systems, in particular lab‐on‐a‐chip systems. Measurements of efficiencies in microfabricated devices under different Joule heating conditions are evaluated and compared to both theoretical models and measurements performed on conventional capillary systems. The widely accepted notion that planar microdevices are less susceptible to Joule heating effects is largely confirmed. The heat dissipation from a nonthermostatically controlled glass microdevice was found to be comparable to that from a liquid‐cooled‐fused silica capillary. Using typically dimensioned glass and glass/silicon microdevices, the experimental results indicate that 5–10 times higher electric field strengths can be applied than on conventional capillaries, before detrimental effects on the separation efficiency occur. The main influence of Joule heating on efficiency is via the establishment of a radial temperature profile across the lumen of the capillary or channel. An overall temperature increase of the buffer solution has only little influence on the quality of the separation. Still, active temperature control (cooling, thermostatting) can help prevent boiling of the buffer and increase the reproducibility of the results.
High‐resolution computer simulation of the dynamics of isoelectric focusing of proteins
Authors: Thormann Wolfgang , Huang Tiemin , Pawliszyn Janusz , Mosher Richard A.
Published: January 2004

A dynamic electrophoresis simulator that accepts 150 components and voltage gradients employed in the laboratory was used to provide a detailed description of the focusing process of proteins under conditions that were hitherto inaccessible. High‐resolution focusing data of four hemoglobin variants in a convection‐free medium are presented for pH 3–10 and pH 5–8 gradients formed with 20 and 40 carrier ampholytes/pH unit, respectively. With 300 V/cm, focusing is shown to occur within 5–10 min, whereas at 600 V/cm separation is predicted to be complete between 2.5 and 5 min. The time interval required for focusing of proteins is demonstrated to be dependent on the input protein charge data and, however less, on the properties of the carrier ampholytes. The simulation data reveal that the number of transient protein boundaries migrating from the two ends of the column towards the focusing positions is equal to the number of sample components. Each protein is being focused via the well‐known double‐peak approach to equilibrium, a process that is also characteristic for focusing of the carrier ampholytes. The predicted focusing dynamics for the hemoglobin variants in pH 3–10 and pH 5–8 gradients are shown to qualitatively agree well with experimental data obtained by whole‐column optical imaging.
Zeta potential of microfluidic substrates: 1. Theory, experimental techniques, and effects on separations
Authors: Kirby Brian J. , Hasselbrink Ernest F.
Published: January 2004

This paper summarizes theory, experimental techniques, and the reported data pertaining to the zeta potential of silica and silicon with attention to use as microfluidic substrate materials, particularly for microchip chemical separations. Dependence on cation concentration, buffer and cation type, pH, cation valency, and temperature are discussed. The Debye‐Hückel limit, which is often correctly treated as a good approximation for describing the ion concentration in the double layer, can lead to serious errors if it is extended to predict the dependence of zeta potential on the counterion concentration. For indifferent univalent electrolytes (e.g., sodium and potassium), two simple scalings for the dependence of zeta potential on counterion concentration can be derived in high‐ and low‐ζ limits of the nonlinear Poisson‐Boltzman equation solution in the double layer. It is shown that for most situations relevant to microchip separations, the high‐ζ limit is most applicable, leading to the conclusion that the zeta potential on silica substrates is approximately proportional to the logarithm of the molar counterion concentration. The ζ vs. pH dependence measurements from several experiments are compared by normalizing the ζ based on concentration.
Peak dispersion and contributions to plate height in nonaqueous capillary electrophoresis at high electric field strengths: Ethanol as background electrolyte solvent
Authors: Palonen Sami , Jussila Matti , Porras Simo P. , Riekkola Marja‐Liisa
Published: January 2004

Nonaqueous capillary electrophoretic separations were performed under high electric field strengths (up to 2000 Vcm−1) in ethanolic background electrolyte solution and the contributions of different band broadening effects to plate height were evaluated. Under optimum conditions, increasing the field strength will provide faster separations and increased separation efficiency. Decrease in the separation efficiency at high field strengths was, however, observed in a previous study and now in the present paper an attempt is made to quantify various band broadening effects by applying a plate height model, which included the contributions of the injection plug length, diffusion, electromigration dispersion, Joule heating, analyte adsorption to the capillary wall, and detector slit aperture length. Of special interest were the contributions of Joule heating and analyte adsorption to the capillary wall. Poly(glycidylmethacrylate‐co‐N‐vinylpyrrolidone)‐coated fused‐silica capillaries were used with internal diameters (ID) ranging from 30 to 75 μm. The separation efficiencies obtained experimentally were compared with the theoretically calculated efficiencies and fairly good agreement was observed for the 30 μm ID capillary. Relatively large deviation from the predictions of the model was found for the other capillary diameters especially at higher field strengths. The possible reasons for the deviation were discussed.
Urinary mutagenesis and fried red meat intake: Influence of cooking temperature, phenotype, and genotype of metabolizing enzymes in a controlled feeding study
Authors: Peters Ulrike , Sinha Rashmi , Bell Douglas A. , Rothman Nathaniel , Grant Delores J. , Watson Mary A. , Kulldorff Martin , Brooks Lance R. , Warren Sarah H. , DeMarini David M.
Published: January 2004

Meat cooked at high temperatures contains potential carcinogenic compounds, such as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). Samples from a 2‐week controlled feeding study were used to examine the relationship between the intake of mutagenicity from meat fried at different temperatures and the levels of mutagenicity subsequently detected in urine, as well as the influence of the genotype of drug metabolizing enzymes on urinary mutagenicity. Sixty subjects consumed ground beef patties fried at low temperature (100°C) for 1 week, followed by ground beef patties fried at high temperature (250°C) the second week. Mutagenicity in the meat was assayed in Salmonella typhimurium TA98 (+S9), and urinary mutagenicity was determined using Salmonella YG1024 (+S9). Genotypes for NAT1, NAT2, GSTM1, and UGT1A1 were analyzed using blood samples from the subjects. Meat fried at 100°C was not mutagenic, whereas meat fried at 250°C was mutagenic (1023 rev/g). Unhydrolyzed and hydrolyzed urine samples were 22× and 131× more mutagenic, respectively, when subjects consumed red meat fried at 250°C compared with red meat fried at 100°C. We found that hydrolyzed urine was ∼8× more mutagenic than unhydrolyzed urine, likely due to the deconjugation of mutagens from glucuronide. The intake of meat cooked at high temperature correlated with the mutagenicity of unhydrolyzed urine (r = 0.32, P = 0.01) and hydrolyzed urine (r = 0.34, P = 0.008). Mutagenicity in unhydrolyzed urine was not influenced by NAT1, NAT2, or GSTM1 genotypes. However, a UGT1A1*28 polymorphism that reduced UGT1A1 expression and conjugation modified the effect of intake of meat cooked at high temperature on mutagenicity of unhydrolyzed urine (P for interaction = 0.04). These mutagenicity data were also compared with previously determined levels of HCAs (measured as MeIQx, DiMeIQx, and PhIP) and polycyclic aromatic hydrocarbons (PAHs) in the meat, levels of HCAs in the urine, and CYP1A2 and NAT2 phenotypes. The levels of mutagenicity in the meat fried at low and high temperatures correlated with levels of HCAs, but not levels of PAHs, in the meat. Also, levels of mutagenicity in unhydrolyzed urine correlated with levels of MeIQx in unhydrolyzed urine (r = 0.36; P = 0.01), and the levels of mutagenicity of hydrolyzed urine correlated with levels of MeIQx (r = 0.34; P = 0.01) and PhIP (r = 0.43; P = 0.001) of hydrolyzed urine. Mutagenicity in unhydrolyzed urine was not influenced by either the CYP1A2 or NAT2 phenotype. The data from this study indicate that urinary mutagenicity correlates with mutagenic exposure from cooked meat and can potentially be used as a marker in etiological studies on cancer. Environ. Mol. Mutagen. 43:53–74, 2004. Published 2004 Wiley‐Liss, Inc.
Blown‐sand transport rate
Authors: Ni Jinren , Li Zhenshan , Mendoza Cesar
Published: January 2004

Several sand transport rate data sets and eight representative transport rate formulae are transformed using the dimensionless parameters ϕ = gQ/ρU3* and r = U*t/U* and the results compared on the (ϕ, r) plane. The formulae generate three different geometric patterns – constant, monotonic decreasing and concave downward – and the corresponding data displayed one more pattern, a monotonic increasing one. Stimulated by this discrepancy, a new general formula for the sand transport rate with ϕ and r as its basis is introduced; each of the representative formulae is either a particular case of it or an approximation to it. The four parameters in the new formula are determined for description of the four possible patterns exhibited by the data; their variation is established and their physical interpretation is discussed in relation to measured data of the characteristic parameters of wind ﬂow and sand. Copyright © 2004 John Wiley & Sons, Ltd.
A distribution‐free statistical method for the spatial characterization of dune granulometry: an example from the Strzelecki Desert, South Australia
Authors: Bishop Mark A.
Published: January 2004

Distribution‐free statistical methods of comparative data analysis have identiﬁed subtle granulometric differences attributed to the evolution of barchan form at Gurra‐Gurra waterhole. Geomorphic locations on the barchan dunes display statistically signiﬁcant grain‐size differences that assist in the interpretation of aeolian processes. In summer, very ﬁne sands mantle the dunescape and are the fraction that most affects the parameters of sorting and skewness. The surﬁcial sedimentological character is one of subtle contrasts between the processes of grain winnowing and intergranular protection. The second and third moment measures are parameters that best demonstrate the spatial granulometric differences. Dune‐forming processes at Gurra‐Gurra have produced dune sands that have a very narrow range of grain size, which, in turn, reﬂects textural and mineralogical maturity, and hence an extensive transport history. The statistical techniques employed in this study can also be used for the comparison of temporal (seasonal) sedimentological change, and for the granulometric analysis and association of process for dunes of different morpho‐types. Copyright © 2004 John Wiley & Sons, Ltd.
Channels, wetlands and islands in the Okavango Delta, Botswana, and their relation to hydrological and sedimentological processes
Authors: Gumbricht T. , McCarthy J. , McCarthy T. S.
Published: January 2004

The Okavango wetland in northern Botswana is one of the world's largest inland deltas. The delta is a dynamic environment with shifting channel routes, causing growth and decay of ﬂanking wetlands, and giving birth to islands. Primary island nuclei are formed by ﬂuvial processes and bioengineering, and subsequently grow into secondary larger islands of irregular shape by clastic and chemical sedimentation, and later by coalescence. This article presents classiﬁcations and quantitative estimations of channels, wetlands and islands of the Okavango Delta. Islands were classiﬁed dependent on composition, pattern of composition, shape and juxtaposition. 90 per cent of all islands in the entire wetland were identiﬁed, with a classiﬁcation accuracy of 60 to 85 per cent. Smaller islands of the nucleus types dominate the upper parts of the delta, whereas larger secondary islands are more common in the distal part, a reﬂection of the age of the islands. Islands in the entry valley of the delta, the Panhandle, are larger in the top end – the primary region of recent clastic sedimentation. The overall size distribution of islands in the delta, however, shows no clumps, indicating that island growth is a uniform process over time and space. The total area ﬂooded at least every decade is approximately 14 000 km2, of which 9000 km2 is classiﬁed as actual wetland. Channel meandering decreases from the Panhandle to the distal part of the delta, with the abandoned Thaoge channel as an exception. Occurrence of ﬂuvially formed islands in the distal delta indicates that the water ﬂow and area of inundation must once have been much larger. Copyright © 2004 John Wiley & Sons, Ltd.
Evidence for freeze–thaw events and their implications for rock weathering in northern Canada
Authors: Hall Kevin
Published: January 2004

Discussions regarding weathering in cold environments generally centre on mechanical processes and on the freeze–thaw mechanism in particular. Despite the almost ubiquitous assumption of freeze–thaw weathering, unequivocal proof of interstitial rock water actually freezing and thawing is singularly lacking. Equally, many studies have used the crossing of 0 °C, or values close to that, as the basis for determining the number of ‘freeze–thaw events’. In order to assess the weathering regime at a site in northern Canada, temperatures were collected at the surface, 1 cm and 3 cm depth for sets of paving bricks, with exposures both vertical and at 45°, orientated to the four cardinal directions. Temperature data were collected at 1 min intervals for 1 year. These data provide unequivocal proof for the occurrence of the freezing and thawing of water on and within the rock (freeze–thaw events). The freeze event is evidenced by the exotherm associated with the release of latent heat as the water actually freezes. This is thought to be the ﬁrst record of such events from a ﬁeld situation. More signiﬁcantly, it was found that the temperature at which freezing occurred varied signiﬁcantly through the year and that on occasion the 1 cm depth froze prior to the rock surface. The change in freeze temperature is thought to be due to the chemical weathering of the material (coupled with on‐going salt inputs via the melting of snowfall), which, it is shown, could occur throughout the winter despite air temperatures down to −30 °C. This ﬁnding regarding chemical weathering is also considered to be highly signiﬁcant. A number of thermal stress events were also recorded, suggesting that rock weathering in cold regions is a synergistic combination of various chemical and mechanical weathering mechanisms. Copyright © 2003 John Wiley & Sons, Ltd.
Patterns of sediment slug translation and dispersion following typhoon‐induced disturbance, Oyabu Creek, Kyushu, Japan
Authors: Kasai Mio , Marutani Tomomi , Brierley Gary J.
Published: January 2004

A six‐year monitoring programme characterized the migration/dispersion patterns of sediment slugs generated following typhoon‐induced disturbances in 1993 and 1997 along a single‐thread gravel‐bed stream, Oyabu Creek, on Kyushu Island, Japan. This laterally conﬁned creek comprises rifﬂe–pool sequences with intervening bedrock outcrops. The passage of sediment pulses associated with sediment slug processes reﬂected, and was controlled by, the rifﬂe–pool structures which provided channel bed roughness, the volume of sediment stored along valley ﬂoors, and the distribution of bedrock outcrops. Changes to bed material size following major sediment inputs during the disturbance events also exerted an inﬂuence on subsequent sediment slug processes. The sequence of rainfall events, together with changes to channel bed structure, induced different phases in the sediment slug processes. The capacity of a reach to store or trap sediment, as recorded by the longitudinal structure of the channel, varied during these differing phases. Copyright © 2004 John Wiley & Sons, Ltd.
Crater formation in soils by raindrop impact
Authors: Ghadiri Hossein
Published: January 2004

The process of crater formation by the impact of water drops on soil, sand and various other target material was studied. Craters of various shapes and sizes were observed on different target materials or conditions, ranging from circumferential depression to completely hemispherical shape. Crater shape was dependent upon target material, its ﬂow stress or shear strength and the presence and thickness of water on the surface. Between 5 and 22 per cent of impact energy was spent on cratering, but the relationship between crater volume and kinetic energy of a raindrop was curvilinear, indicating a lower efﬁciency of impact energy in removing target material as the energy increases. Impact impulse, on the other hand, showed a more linear relationship with crater volume, and the ratio of impulse over crater volume (I/V) remained constant for the entire range of drop sizes, impact velocities, and surface conditions used in this study. Surface shear strength, represented by the penetration depth of fall‐cone penetrometer, appeared to be a key factor involved in this process. An equation was developed which related crater volume to cone penetration depth and impact impulse. Crater volume, which appeared to be a better indicator of the total amount of material dislodged by a raindrop than splash amount, can thus be predicted using this equation. Copyright © 2004 John Wiley & Sons, Ltd.
Longitudinal velocity patterns and bed morphology interaction in a rill
Authors: Giménez Rafael , Planchon Olivier , Silvera Norbert , Govers Gerard
Published: January 2004

Present‐day understanding of rill dynamics is hampered by a lack of detailed data on velocity distributions in rills. The latter are difﬁcult to collect with traditional techniques due to the very low water depths and the relatively high ﬂow velocities in rills. The objectives of this paper were to investigate the feasibility of miniaturized acoustic Doppler velocimeter (mADV) measurements in rill ﬂow and to explore longitudinal variations in ﬂow velocities and their relationship with rill bed morphology. Detailed data on longitudinal ﬂow velocity were required to achieve these objectives.

A 1·8 m long rill was formed freely in a ﬂume at 5° slope and 0·001 m3 s−1 discharge. Rill topography was characterized by an alternation of steps and pools. The ﬂume surface was then ﬁxed to preserve rill roughness. A topographical scanning of the entire ﬂume surface was made. Velocity was measured with a mADV along the rill, and at different depths. Flow depth in a longitudinal direction was also measured using an elevation gauge.

A strong relationship exists between rill topography and ﬂow hydraulics. Over steps, ﬂow was unidirectional and rapidly accelerating until a threshold Froude number (Fn) value between 1·3 and 1·7 was reached and a hydraulic jump occurred leading to the formation of a pool. In the pool, the ﬂow pattern was multidirectional and complex. The ﬂow was subcritical when leaving the pool and accelerated over the next step until the threshold Froude number value was again reached. Energy loss in the rill was concentrated in the pools, mainly due to the action of a hydraulic jump. This mechanism of energy dissipation appeared to be an essential factor in rill formation and bedform evolution. Copyright © 2004 John Wiley & Sons, Ltd.
Representing the landslide magnitude–frequency relation: Capilano River basin, British Columbia
Authors: Brardinoni Francesco , Church Michael
Published: January 2004

We use magnitude–frequency analysis as a statistical tool to quantify the erosion caused by landslides and debris ﬂows. Using air‐photo‐ and ground‐derived data we show that the departure from power‐law distribution customarily observed for small magnitude is an artefact of sampling deﬁciencies. Nonetheless, the total distribution is not sensitive to the frequency of small slides and total erosion remains adequately represented in the air‐photo‐derived data. Our data also demonstrate a real departure from simple scaling at much larger magnitudes, the cause of which is not deﬁnitively established. Copyright © 2004 John Wiley & Sons, Ltd.
Identifying and nurturing potential academic leaders
Authors: Hoppe Sherry L.
Published: January 2004

Selecting and nurturing academic leaders requires identifying effective leadership characteristics and providing experiences for potential candidates that both test and develop them.
Six critical issues for midlevel leadership in postsecondary settings
Authors: Filan Gary L. , Seagren Alan T.
Published: January 2004

The complex responsibilities of academic leadership require multidimensional training, exemplified in the six principles undergirding the internationally recognized program examined here.
The role of professional development in preparing academic leaders
Authors: Raines Shirley C. , Alberg Martha Squires
Published: January 2004

While the best professional development for aspiring administrators may simply be to spend time in the company of leaders, more formal experiences can entail internship, mentor alignment, and institutes.
Selected legal aspects of academic administrative leadership: An orientation for new academic administrators
Authors: Jenkins Charles R.
Published: January 2004

The basis for sound administrative decisions in colleges and universities lies in broad‐based knowledge of federal and state constitutional and statutory provisions, case law, policies of governing boards, and other legal issues affecting higher education.
The rewards of academic leadership
Authors: Murphy Christina
Published: January 2004

Understanding the nature of academic leadership aids in the identification of both extrinsic and intrinsic rewards to motivate commitment to difficult yet critical roles in the academy.
Enhancement of tumor radioresponse by combined treatment with gefitinib (Iressa, ZD1839), an epidermal growth factor receptor tyrosine kinase inhibitor, is accompanied by inhibition of DNA damage repair and cell growth in oral cancer
Authors: Shintani Satoru , Li Chunnan , Mihara Mariko , Terakado Nagaaki , Yano Junya , Nakashiro Koh‐ichi , Hamakawa Hiroyuki
Published: January 2004

Molecular blockade of EGFR with either an EGFR MAb or an EGFR TKI enhances the radiosensitivity of human SCCs. In the present study, we investigated whether treatment with the EGFR TKI gefitinib (Iressa, ZD1839) improves the response to radiotherapy in the OSCC cell lines HSC2 and HSC3. We examined potential mechanisms that may contribute to the enhanced radiation response induced by gefitinib. Growth inhibition was observed in vitro with radiation or gefitinib. A cooperative antiproliferative effect was obtained when cancer cells were treated with radiation followed by gefitinib. Cells treated with a combination of radiation and gefitinib arrested in G1 and G2–M phases, with a decrease in the S‐phase population. While radiation alone did not significantly affect MEK1/2 and p38 MAPK autophosphorylation, the combination of gefitinib and radiation completely inhibited the downstream signaling of EGFR. Results from DNA damage repair analysis in cultured OSCC cells demonstrated that gefitinib had a strong inhibitory effect on DNA‐PKc pathways after radiation. Tumor xenograft studies demonstrated that the combination of gefitinib and radiation caused growth inhibition and tumor regression of well‐established OSCC tumors in athymic mice; tumor volume was reduced from 1,008.2 to 231.4 mm3 in HSC2 cells (p < 0.01) and from 284.2 to 12.4 mm3 in HSC3 cells (p < 0.01). Immunohistochemical analysis of OSCC xenografts revealed that gefitinib caused a striking decrease in tumor cell proliferation when combined with radiotherapy. Overall, we conclude that gefitinib enhances tumor radioresponse by multiple mechanisms that may involve antiproliferative growth inhibition and effects on DNA repair after exposure to radiation. © 2003 Wiley‐Liss, Inc.
Decrease of human pancreatic cancer cell tumorigenicity by α1,3galactosyltransferase gene transfer
Authors: Aubert Muriel , Crotte Christian , Bernard Jean‐Paul , Lombardo Dominique , Sadoulet Marie‐Odile , Mas Eric
Published: January 2004

The enzyme α1,3galactosyltransferase synthesizes the αGal epitope, a carbohydrate structure (Galα1,3Galβ1,4GlcNAc‐R), on glycoconjugates in lower mammals. The enzyme is absent in humans but large amounts of natural antibodies that recognize αGal epitopes are present in human serum. It is likely that these antibodies contribute to the host defense and participate in the hyperacute rejection of xenograft. Previous studies indicated that the glycosyltransferase gene transfer into tumoral cells can modify the structure of glycoconjugates at the cell surface and, as a consequence, modulates the metastatic and tumorigenic behaviors of these cells. The aim of our study was to determine whether the expression of αGal epitope can modify the tumorigenicity of human pancreatic cancer cells. The expression of αGal epitopes in the human pancreatic cancer cell lines BxPC‐3 and Panc‐1 was obtained by selecting stable cell clones transfected with murine α1,3galactosyltransferase gene. The expression of the enzyme activity in BxPC‐3 and Panc‐1 cells resulted in the formation at the cell surface of αGal epitopes that are recognized by human anti‐αGal antibodies. αGal epitope expression at the surface of pancreatic cancer cells was associated with the fixation of complement 1q to human anti‐αGal antibodies. The αGal epitope expression also resulted in a delay in the tumoral development of BxPC‐3 and Panc‐1 cells in vivo after xenograft transplantation of nude mice. In addition to the impairment of the metastatic potential of murine tumor cell lines and the activation of immune response, our study provides evidence that the cell surface expression of αGal epitopes also modulates the tumorigenic behavior of human pancreatic cancer cells. © 2003 Wiley‐Liss, Inc.
Detection of breast cancer cells in the peripheral blood is positively correlated with estrogen‐receptor status and predicts for poor prognosis
Authors: Gaforio José‐Juan , Serrano María‐José , Sanchez‐Rovira Pedro , Sirvent Antonio , Delgado‐Rodriguez Miguel , Campos María , de la Torre Nicolás , Algarra Ignacio , Dueñas Rosario , Lozano Ana
Published: January 2004

We investigated whether detection of cytokeratin‐positive (CK+) cells in the peripheral blood (PB) of breast cancer patients before chemotherapy could be a prognostic factor. Blood from a total of 92 breast cancer patients was evaluated for the presence of CK+ cells. Blood samples were collected before chemotherapy. Patients entered in the study included: neoadjuvant (n = 25), adjuvant (n = 42) and metastatic (n = 25). Blood samples (10 ml) were centrifuged using a double density‐gradient to recovering the mononuclear cell (MNC) and granulocyte cell (GC) fractions. Subsequently, positive immunomagnetic cell separation was carried out to isolating CK+ cells. The enriched cell fraction was cytocentrifuged and then immunocytochemically labeled using an anti‐cytokeratin antibody. Our results indicated that breast tumor cells sediment with both MNC and GC fractions. We therefore recommend examination of both fractions in all enrichment protocols. CK+ cells in PB were identified in 57 of 92 (62%) patients when MNC and GC fractions were assessed (range = 1–61 cells, median = 8). No CK+ cells were detected in blood samples of 16 healthy donors. There were significant differences in the presence of CK+ cells according to estrogen receptor expression (p = 0.049), and lymph node status (p = 0.033), but not to the age, menopausal status, type of patient (neoadjuvant, adjuvant or metastatic), TNM stage, histological type, progesterone receptor expression, c‐erbB2 expression, p53 expression or Ki67 expression. Regarding the relationship between tumor size (T) and the presence of CK+ cells, a borderline significant trend was observed (p = 0.07). The median follow‐up of the patients was 21 months and statistical analysis (Kaplan‐Meier analysis) showed that using the method we present, the detection of CK+ cells in PB before starting the chemotherapy in breast cancer patients was significantly correlated with both progression‐free survival (p = 0.058) and overall survival (p = 0.003). In conclusion, the present study suggests that detection of CK+ cells in PB before chemotherapy might identify breast cancer patients with poor prognosis. © 2003 Wiley‐Liss, Inc.
Birth weight and risk of breast cancer in a cohort of 106,504 women
Authors: Ahlgren Martin , Sørensen Thorkild , Wohlfahrt Jan , Haflidadóttir Ágústa , Holst Claus , Melbye Mads
Published: January 2004

The possible association between prenatal factors and breast cancer has been discussed for more than a decade. Birth weight has been used commonly as a proxy measure for intrauterine growth. Whereas some previous studies have found support for an association between birth weight and breast cancer, others have been inconclusive or found no association. We investigated the relationship between birth weight and risk of female breast cancer in a cohort of 106,504 Danish women. Birth weights were obtained from school health records on girls born between 1930–1975. Information on breast cancer came from linking the cohort with the Danish Cancer Registry and the Danish Breast Cancer Cooperative Groups Registry. A total of 2,334 cases of primary breast cancer were diagnosed in the cohort during 3,255,549 person‐years of follow‐up among women with birth weight between 500–6,000 g. Of these, 922 (40%) were diagnosed with primary breast cancer at the age of 50 years or older. A significant association between birth weight and breast cancer was found equivalent to an increase in risk of 9% per 1,000 g increase in birth weight (95% CI 2–17). The increase was observed for all age groups, representing both pre‐ and post‐menopausal women, and irrespective of tumor characteristics. Adjustment for age at first birth and parity did not influence the results. Birth weight is positively associated with risk of breast cancer, indicating that prenatal factors are important in the etiology of breast cancer. © 2003 Wiley‐Liss, Inc.