bluuebunny/crossref_metadata_2025 huggingface dataset:
N‐Carboxamido‐staurosporine (I) and Selina‐4(14),7(11)‐diene‐8,9‐diol (II), New Metabolites from a Marine Streptomyces sp.
Authors: Wu Shao Jie , Fotso Serge , Li Fuchao , Qin Song , Kelter Gerhard , Fiebig Heinz H. , Laatsch Hartmut
Published: November 2006

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.
Stereoselective Synthesis of (‐)‐Trachelanthamidine (IV) via Palladium‐Catalyzed Intramolecular Allylation.
Authors: Craig Donald , Hyland Christopher J. T. , Ward Simon E.
Published: November 2006

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.
Total Synthesis of (.+‐.)‐Mitorubrinic Acid.
Authors: Marsini Maurice A. , Gowin Kristoffer M. , Pettus Thomas R. R.
Published: November 2006

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.
Asymmetric Total Synthesis of (‐)‐Panacene and Correction of Its Relative Configuration.
Authors: Boukouvalas John , Pouliot Martin , Robichaud Joel , MacNeil Stephen , Snieckus Victor
Published: November 2006

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.
Chemical Synthesis of ComX Pheromone and Related Peptides Containing Isoprenoidal Tryptophan Residues.
Authors: Okada Masahiro , Sato Isao , Cho Soo Jeong , Dubnau David , Sakagami Youji
Published: November 2006

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.
Hypocrellin D, a Cytotoxic Fungal Pigment from Fruiting Bodies of the Ascomycete Shiraia bambusicola
Authors: Fang Li‐Zhen , Qing Chen , Shao Hong‐Jun , Yang Yi‐Dong , Dong Ze‐Jun , Wang Fei , Zhao Wei , Yang Wan‐Qiu , Liu Ji‐Kai
Published: November 2006

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.
Al—Cr—Mo—Ni (Aluminum—Chromium—Molybdenum—Nickel)
Authors: Raghavan V.
Published: November 2006

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.
Al—Co—Cr—Ni (Aluminum—Cobalt—Chromium—Nickel)
Authors: Raghavan V.
Published: November 2006

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.
Al—Ni—Ta (Aluminum—Nickel—Tantalum)
Authors: Raghavan V.
Published: November 2006

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.
Al—Nd—Ni (Aluminum—Neodymium—Nickel)
Authors: Raghavan V.
Published: November 2006

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.
Al—Mo—Ni (Aluminum—Molybdenum—Nickel)
Authors: Raghavan V.
Published: November 2006

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.
Al—Cu—Ni (Aluminum—Copper—Nickel)
Authors: Raghavan V.
Published: November 2006

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.
Electron‐Correlation Effects in a Disordered Fe2TiSn Heusler Alloy
Authors: Slebarski Andrzej
Published: November 2006

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.
Photorefractive Cyclometalated Complexes
Authors: Termine R. , Talarico M. , Aiello I. , Dattilo D. , Pucci D. , Ghedini M. , Golemme A.
Published: November 2006

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.
Recent Developments in the Syntheses of the Epothilones and Related Analogues
Authors: Watkins E. Blake , Chittiboyina Amar G. , Avery Mitchell A.
Published: November 2006

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.
Reactions Between Aliphatic Amines and [60]Fullerene
Authors: Miller Glen P.
Published: November 2006

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.
Recent Developments in Enantioselective Phase‐Transfer Catalysis Using Chiral Ammonium Salts
Authors: Vachon Jerome , Lacour Jerome
Published: November 2006

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.
Proton Transfer Reactions in the Excited States
Authors: Shizuka Haruo , Tobita Seiji
Published: November 2006

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.
Control of Chirality: From Asymmetric Catalysis to Nanomachines
Authors: Feringa Ben L.
Published: November 2006

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.
Rolling Out Advances in Chiral Chemistry
Authors: Van Arnum Patricia
Published: November 2006

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.
Five‐Membered Ring Systems with O and N Atoms
Authors: Cicchi Stefano , Cordero Franca M. , Giomi Donatella
Published: November 2006

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.
Five‐Membered Ring Systems with More than One N Atom
Authors: Yet Larry
Published: November 2006

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.
Eight‐Membered and Larger Ring Systems
Authors: Newkome George R.
Published: November 2006

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.
[2.2.n]MMetacyclophanes: Syntheses, Structure, and Functionalization
Authors: Sawada Tsuyoshi
Published: November 2006

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.
Synthesis and Properties of Homooxacalix[3]arenes
Authors: Tsubaki Kazunori
Published: November 2006

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.
Six‐Membered Ring Systems: Pyridines and Benzo Derivatives
Authors: Comins Daniel L. , Dinsmore Jason , O'Connor Sean
Published: November 2006

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.
Five‐Membered Ring Systems: Pyrroles and Benzo Derivatives
Authors: Janosik Tomasz , Bergman Jan
Published: November 2006

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.
Five‐Membered Ring Systems: Thiophenes and Se/Te Analogues
Authors: Seshadri Venkataramanan , Selampinar Fatma , Sotzing Gregory A.
Published: November 2006

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.
Five‐Membered Ring Systems: Thiophenes and Se/Te Analogues
Authors: Janosik Tomasz , Bergman Jan
Published: November 2006

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.
Prediction of the Phase Behavior of Hydrogen‐Bonded Polymer Blends
Authors: Coleman Michael M. , Painter Paul C.
Published: November 2006

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.
Computational Approaches for Predicting CYP‐Related Metabolism Properties in the Screening of New Drugs
Authors: Crivori P. , Poggesi I.
Published: November 2006

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.
Polymer Chemistry in Diabetes Treatment by Encapsulated Islets of Langerhans: Review to 2006
Authors: Lacik Igor
Published: November 2006

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.
Chemiluminescence as a Probe of Polymer Oxidation
Authors: Blakey Idriss , Goss Ben , George Graeme
Published: November 2006

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.
Progress of Solid‐Phase Microextraction Coatings and Coating Techniques
Authors: Jiang Guibin , Huang Minjia , Cai Yaqi , Lv Jianxia , Zhao Zongshan
Published: November 2006

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.
NMR of Conotoxins: Structural Features and Analysis of Chemical Shifts of Posttranslationally Modified Amino Acids
Authors: Marx Ute C. , Daly Norelle L. , Craik David J.
Published: November 2006

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.
Per‐O‐Methylation Reaction for Structural Analysis of Carbohydrates by Mass Spectrometry
Authors: Ciucanu Ionel
Published: November 2006

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.
Adenosine triphosphate‐binding cassette B1 (ABCB1) (multidrug resistance 1) G2677T/A gene polymorphism is associated with high risk of lung cancer
Authors: Gervasini Guillermo , Carrillo Juan Antonio , Garcia Montserrat , San Jose Carmen , Cabanillas Agustin , Benitez Julio
Published: November 2006

BACKGROUND.

P‐glycoprotein (P‐gp) is a transmembrane transporter that is encoded by the adenosine triphosphate‐binding cassette B1 (ABCB1) (multidrug resistance 1) gene, which plays a role in cell defense against environmental attacks, like those generated by xenobiotics. P‐gp is expressed in the lung, where it has been suggested to transport these compounds from the interstitium into the lumen.

METHODS.

Two functional ABCB1 polymorphisms were examined, G2677T/A (in exon 21) and C3435T (in exon 26), in a group of lung cancer patients and in a control group.

RESULTS.

Whereas 3435T allelic and genotype frequencies were unchanged between both study groups, lung cancer patients showed higher frequency of the 2677T variant allele compared with the control group (0.67 vs. 0.43; P < .001; odds ratio, [OR], 2.6; 95% confidence interval [95% CI], 1.7–4.0). Among the histologic tumor types that were included in the study, squamous cell carcinoma was associated most strongly with the presence of the 2677T allele (OR, 3.92; 95% CI, 2.2–6.9) and especially was associated with the 2677 TT genotype (OR, 6.75; 95% CI, 3.0–15.2). In a haplotype analysis, homozygous wild‐type alleles were classified as genotype A, heterozygous alleles were classified as genotype B, and homozygous mutant allele were classified as genotype C both in exon 21 (first letter) and in exon 26 (second letter) loci. The haplotype CB displayed the highest association with lung cancer (OR, 18.09; 95% CI, 2.4–139.2).

CONCLUSIONS.

The current results taken together suggest that, aside from other known causes of lung cancer, such as tobacco smoke, the existence of polymorphisms in the ABCB1 gene and, specifically, the presence of the G2677T mutation can be crucial in conferring susceptibility to lung cancer. Further studies comprising larger populations are needed to confirm these preliminary findings. Cancer 2006. © 2006 American Cancer Society.
Prolonged follow‐up after initial therapy with 2‐chlorodeoxyadenosine in patients with indolent non‐Hodgkin lymphoma
Authors: Blum Kristie A. , Johnson Jeffrey L. , Niedzwiecki Donna , Piro Lawrence D. , Saven Alan , Peterson Bruce A. , Byrd John C. , Cheson Bruce D. ,   for the Cancer and Leukemia Group B
Published: November 2006

BACKGROUND.

The objective of this study was to determine the efficacy and toxicity of 2‐chlorodeoxyadenosine (2‐CdA) in patients with untreated, indolent non‐Hodgkin lymphoma (NHL).

METHODS.

For this multicenter, single‐arm, Phase II study, 44 patients with treatment‐naive, stage III or IV, indolent NHL (International Working Formulation subtypes A, B, and C) were enrolled. Patients received 0.14 mg/kg per day of 2‐CdA as a 2‐hour bolus infusion for 5 consecutive days every 28 days until maximal response or a total of 6 cycles.

RESULTS.

Thirty‐eight patients were eligible for response evaluation. The overall response rate was 100% (95% confidence interval [95% CI], 90.8–100%), and the complete response rate was 31.6% (95% CI, 17.5–48.7%). In the intent‐to‐treat population, the median failure‐free survival was 2.0 years (95% CI, 1.3–3.4 years), and the overall survival rate was 7.0 years (95% CI, 4.3–9.4 years). Six patients had sustained remissions that lasted a median of 8.7 years (range, from 5.9 years to ≥11 years). Although 68% of patients experienced at least 1 grade 3 or 4 event, consisting primarily of myelosuppression, severe infections were rare, with only 8 grade 3 infections. Four late malignancies (prostate adenocarcinoma, ductal carcinoma in situ, and myelodysplasia) and 4 patients with large cell transformation were reported.

CONCLUSIONS.

2‐CdA is an active, well‐tolerated therapy for patients with untreated, indolent NHL. Cancer 2006. © 2006 American Cancer Society.
Productivity and performance through components: the ASCI Sweep3D application
Authors: Yoon Young , Browne James C. , Crocker Mathew , Jain Samit , Mahmood Nasim
Published: November 2006

This paper is a case study of the effectiveness of component‐oriented development for enhancing both productivity and performance for parallel programs. A process for converting monolithic applications into semantically composable components is described. The supporting software, the P‐COM2 compositional compiler, is briefly described. The componentized version of Sweep3D is described. Productivity is illustrated by composing different instances of the Sweep3D code through automated composition of components using P‐COM2. These instances, each of which targets improving performance for some execution environment or problem case, are examples of a family of instances which are composable from a modest set of components. It is found that customization of componentized codes by component‐level adaptation may yield substantial performance improvement for specific execution environments. We identify and explain some of the benefits of component‐oriented development for high‐performance parallel systems. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and Characterisation of Dinuclear Nickel(II) and Cadmium(II) Complexes of N‐Alkylated Derivatives of Hexaazadithiophenolate Macrocycles
Authors: Gressenbuch Mathias , Kersting Berthold
Published: November 2006

The effect of N‐alkylation on the ligating properties of the Robson‐type 24‐membered hexaazadithiophenolate macrocycle H2L1 [13,27‐bis(tert‐butyl)‐3,6,9,17,20,23‐hexaazatricyclo[23.3.111,15]triaconta‐1(28),11,13,15(30),25,26‐hexaene‐29,30‐dithiol] has been examined. Two new derivatives (H2L3 and H2L4) of H2L1 have been prepared. H2L3 is a dimethylated derivative of H2L1 and H2L4 is a tetraethylated derivative of H2L3. A series of complexes of the type [(LR)MII2(μ‐Cl)]+ [R = 1, M = Cd (10), R = 3, M = Ni (8), M = Cd (12), R = 4, M = Ni (9), M = Cd (13)] have been prepared and structurally characterised. The X‐ray crystal structure determination of these dioctahedral complexes with an N3M(S)2(μ‐Cl)MN3 core structure has revealed two conformations of the supporting ligands. In 8, 9, 10 and 12 the ligands adopt a folded Cs‐symmetric conformation of type A whereas in the cadmium complex 13 the alternative C2v‐symmetric “bowl‐shaped” conformation (type B) is present. A structural comparison has allowed us to determine the factors that determine the ligand conformations. It has been established that the ligand conformations adopted depend not only on the co‐ligand but also on the metal ion radius and the N‐alkylation grade. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis, Structures and Comparison of Neutral Complexes Formed by2‐(2′‐Pyridyl)indole and d6 Transition Metals
Authors: Neumann Bernd , Krinninger Christoph , Lorenz Ingo‐Peter
Published: November 2006

2‐(2′‐Pyridyl)indole acts as an N,N‐bidentate ligand when deprotonated and forms (1‐amido‐4‐imine)metallacycles with ReI, RuII, RhIII and IrIII. The crystal structures of 2‐(2′‐pyridyl)indole and the complexes [Re(C13H9N2)(CO)2(PPh3)2], [Ru(C13H9N2)(η6‐C6Me6)Cl], [Rh(C13H9N2)(η5‐C5Me5)Cl] and [Ir(C13H9N2)(η5‐C5Me5)Cl] are presented and their spectra discussed. This provides a foundation for the increased use of this ligand, which is a prototype of a monoanionic, bidentate N,N‐chelating ligand. The introduction of negatively charged N,N‐bidentate ligands can increase the possibility of synthesising complexes tailored to catalysis and other applications. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Planar Chiral (Arene)chromiumcarbonyl‐Substituted Propargyl Cations – A Spectroscopic and Computational Study
Authors: Netz Astrid , Drees Markus , Strassner Thomas , Müller Thomas J. J.
Published: November 2006

Planar chiral (arene)Cr(CO)3‐substituted propargyl cations can be diastereoselectively generated from propargyl acetates with the use of strong Lewis acids, and they have been structurally characterized by UV/Vis and 13C NMR spectroscopy. At low temperatures (<–65 °C) the s‐cis isomer is exclusively obtained as a product of a kinetically controlled ionization. DFT studies on the structure of the propargyl cations and on the Cipso–Cα bond rotation to give the thermodynamically favored s‐trans isomer reveal that the substitution pattern at the γ‐propargyl position has a stronger impact on the height of the rotational barrier than the substituent on the complexed aryl ring. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Regioselective Base‐Promoted Nucleophilic Ring Opening of Spirocyclic 2,6‐Dioxopiperazines: Synthesis of N‐(1‐Carboxycyclohexyl)amino Acid Derivatives
Authors: González‐Vera Juan A. , García‐López M. Teresa , Herranz Rosario
Published: November 2006

Amino acid derived spirocyclic 2,6‐dioxopiperazines are easily and regioselectively opened by base‐promoted nucleophilic attack of hydroxide or H2O on the less crowded carbonyl group at C‐6 to give N‐(1‐carbamoylcyclohexyl)amino acid derivatives. However, the imide group of the 2,6‐dioxopiperazine ring is rather unreactive toward alcohols, alkoxides, and amines. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Construction of Highly Substituted Stereodefined Dienes by Cross‐Coupling of α‐Allenic Acetates
Authors: Schneekloth John S. , Pucheault Mathieu , Crews Craig M.
Published: November 2006

The assembly of highly substituted dienes remains a challenge for organic chemistry. This work represents a strategyfor the construction of highly substituted 1,3‐dienes by meansof a Tsuji–Trost cross coupling between α‐allenic acetates and organozinc reagents. The reaction is high yielding, and installs a trisubstituted olefin with E/Z selectivities up to 95:5 favoring the (E) product. A cheap, commercially available palladium precatalyst and a ligand are used to control theE/Z selectivity. Furthermore, an interesting reversal in selectivity is noted in which appropriate choice of ligand may be used to control the outcome of the reaction and favor the (Z) product. Thirteen examples are described, highlighting the substrate scope of the reaction. It is hoped that the straightforward reaction conditions and high selectivity will make this reaction of broad use in natural product chemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis of Alaninyl and N‐(2‐Aminoethyl)glycinyl Amino Acid Derivatives Containing the Green Fluorescent Protein Chromophore in Their Side Chains for Incorporation into Peptides and Peptide Nucleic Acids
Authors: Stafforst Thorsten , Diederichsen Ulf
Published: November 2006

Artificial amino acids carrying either the chromophore of the Green Fluorescent Protein (GFP) or a modification as their side chains have been synthesized: Boc‐protected alaninyl derivatives and Fmoc‐protected N‐(2‐aminoethyl)glycine‐functionalized amino acids were obtained and could be applied in solid‐phase peptide synthesis. The incorporation of the GFP chromophore into N‐(2‐aminoethyl)glycine‐PNA was achieved and fluorescence was studied as a function of hybridization with complementary DNA. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Asymmetric Synthesis of Antithrombotic Agents M58163 and M58169: Dynamic Kinetic Resolution in Amide Formation Catalyzed by La‐Linked BINOL Complex
Authors: Saitoh Fumihiko , Nishida Hidemitsu , Mukaihira Takafumi , Aikawa Kohsuke , Mikami Koichi
Published: November 2006

The first asymmetric syntheses of antithrombotic agents M58163 and M58169 are reported. Dynamic kinetic resolution is observed in the amide formation step. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Novel Building Blocks: 1‐Aryl‐2‐chloro‐1‐ethoxyethenes – Preparations and Transformations
Authors: Yoshimatsu Mitsuhiro , Sakai Miho , Moriura Eri
Published: November 2006

We described here a simple method for the preparation of 1‐aryl‐2‐chloro‐1‐ethoxyethenes 2a–u, which are prodrugs for Alzheimer's disease, by the reaction of dichloroacetaldehyde diethyl acetal with various aryl and alkenyllithium compounds in high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Patterning microbeads inside poly(dimethylsiloxane) microfluidic channels and its application for immobilized microfluidic enzyme reactors
Authors: Zhang Qing , Xu Jing‐Juan , Chen Hong‐Yuan
Published: November 2006

We propose a convenient and reliable approach for immobilizing microbeads on poly(dimethylsiloxane) (PDMS) microchips. It is built upon a simple fabrication procedure of PDMS chip through directly printing the master with an office laser printer which was described in our previous work (J. Chromatogr. A 2005, 1089, 270–275). On the printed toners used as the positive relief of the master, microbeads were immobilized by a thermal treatment and then transferred to the surface of the microchip by direct molding of the prepolymer on the master. With this approach, the region‐selective immobilization of microbeads and the fabrication of PDMS microchips can be accomplished at the same time. Then, using these microbeads as supports, further modification with enzyme was achieved. Surface characteristics of the microbeads‐modified PDMS microchannels were investigated with scanning electron microscope, atomic force microscope, and inverse fluorescence microscope. The electrokinetic properties of the native PDMS and the modified PDMS chips were also compared. Based on this approach, an immobilized glucose oxidase (GOD) reactor was constructed and the reaction using glucose as substrate was studied. All these experiments aim to show that the proposed approach may have a good potential in the study of biochemistry and other related areas.
Integration of nanoporous membranes for sample filtration/preconcentration in microchip electrophoresis
Authors: Long Zhicheng , Liu Dayu , Ye Nannan , Qin Jianhua , Lin Bingcheng
Published: November 2006

Microfluidic devices integrating membrane‐based sample preparation with electrophoretic separation are demonstrated. These multilayer devices consist of 10 nm pore diameter membranes sandwiched between two layers of PDMS substrates with embedded microchannels. Because of the membrane isolation, material exchange between two fluidic layers can be precisely controlled by applied voltages. More importantly, since only small molecules can pass through the nanopores, the integrated membrane can serve as a filter or a concentrator prior to microchip electrophoresis under different design and operation modes. As a filter, they can be used for separation and selective injection of small analytes from sample matrix. This has been effectively applied in rapid determination of reduced glutathione in human plasma and red blood cells without any off‐chip deproteinization procedure. Alternatively, in the concentrator mode, they can be used for online purification and preconcentration of macromolecules, which was illustrated by removing primers and preconcentrating the product DNA from a PCR product mixture.
The origin, typology, spatial distribution and detrimental effects of the sinkholes developed in the alluvial evaporite karst of the Ebro River valley downstream of Zaragoza city (NE Spain)
Authors: Gutiérrez F. , Galve J.P. , Guerrero J. , Lucha P. , Cendrero A. , Remondo J. , Bonachea J. , Gutiérrez M. , Sánchez J.A.
Published: November 2006

Three types of sinkhole have been mapped in a 50 km2 stretch of the Ebro River valley downstream of Zaragoza: large collapse sinkholes, large shallow subsidence depressions and small cover‐collapse sinkholes. The sinkholes relate to the karstification of evaporitic bedrock that wedges out abruptly downstream, giving way to a shale substratum. Twenty‐three collapse sinkholes, up to 50 m in diameter by 6 m deep, and commonly hosting saline ponds, have been identified in the floodplain. They have been attributed to the upward stoping of dissolutional cavities formed within the evaporitic bedrock by rising groundwater flows. Twenty‐four large shallow subsidence depressions were mapped in the floodplain. These may reach 850 m in length and were formed by structurally controlled interstratal karstification of soluble beds (halite or glauberite? and gypsum) by rising groundwater flow and the progressive settlement of the overlying bedrock and overburden sediments. A total of 447 small cover‐collapse, or dropout, sinkholes have been recognized in a perched alluvial level along the southern margin of the valley. These sinkholes result from the upward propagation of voids through the alluvial mantle caused by the downward migration of detrital sediments into dissolutional voids. The majority of these sinkholes, commonly 1·5–2 m in diameter, are induced by human activities. Over the karstic bedrock, there is a significant increase in sinkhole density downstream. This is interpreted as being a result of the evaporitic bedrock wedging out and the convergence of the groundwater flow lines in the karstic aquifer. The collapse sinkholes in this area, locally with a probability of occurrence higher than 140 sinkholes/km2/year, cause substantial damage to the linear infrastructures, buildings and agriculture, and they might eventually cause the loss of human lives. Copyright © 2006 John Wiley & Sons, Ltd.
Contemporary versus long‐term denudation along a passive plate margin: the role of extreme events
Authors: Tomkins K. M. , Humphreys G. S. , Wilkinson M. T. , Fink D. , Hesse P. P. , Doerr S. H. , Shakesby R. A. , Wallbrink P. J. , Blake W. H.
Published: November 2006

Short‐term (contemporary) and long‐term denudation rates were determined for the Blue Mountains Plateau in the western Sydney Basin, Australia, to explore the role of extreme events (wildfires and catastrophic floods) in landscape denudation along a passive plate margin. Contemporary denudation rates were reconstructed using 40 years of river sediment load data from the Nattai catchment in the south‐west of the basin, combined with an analysis of hillslope erosion following recent wildfires. Long‐term denudation rates (10 kyr–10 Myr) were determined from terrestrial cosmogenic nuclides, apatite fission track thermochronology and post‐basalt flow valley incision. Contemporary denudation rates average several times lower than the long‐term average (5·5 ± 4 mm kyr−1 versus 21·5 ± 7 mm kyr−1). Erosion of sediment following wildfires accounts for only a small proportion (5%) of the contemporary rate. Most post‐fire sediment is stored on the lower slopes and valley floor, with the amount transported to the river network dependent on rainfall–run‐off conditions within the first few years following the fire. Historical catastrophic floods account for a much larger proportion (35%) of the contemporary erosion rate, and highlight the importance of these events in reworking stored material. Evidence for palaeofloods much larger than those experienced over the past 200 years suggests even greater sediment export potential. Mass movement on hillslopes along valleys incised into softer lithology appears to be a dominant erosion process that supplies substantial volumes of material to the valley floor. It is possible that a combination of infrequent mass movement events and high fluvial discharge could account for a significant proportion of the discrepancy between the contemporary and long‐term denudation rates. Copyright © 2006 John Wiley & Sons, Ltd.
Direct 2D simulation of small gas bubble clusters: from the expansion step to the equilibrium state
Authors: Bruchon J. , Fortin A. , Bousmina M. , Benmoussa K.
Published: November 2006

A numerical strategy, based on an adaptive finite element method, is proposed for the direct two‐dimensional simulation of the expansion of small clusters of gas bubbles within a Newtonian liquid matrix. The velocity and pressure fields in the liquid are first defined through the Stokes equations and are subsequently extended to the gas bubbles. The liquid–gas coupling is imposed through the stress exerted on the liquid by gas pressure (ruled by an ideal gas law) and by surface tension. A level set method, combined with a mesh adaptation technique, is used to track liquid–gas interfaces. Many numerical simulations are presented. The single bubble case allows to compare the simulations to an analytical model. Simulations of the expansion of small clusters are then presented showing the interaction and evolution of the gas bubbles to an equilibrium state, involving topological rearrangements induced by Plateau's rule. Copyright © 2006 John Wiley & Sons, Ltd.
Aerosols dispersion modelling using probabilistic particle tracking
Authors: Smirnov Andrei , Rowan Steven , McCormick James
Published: November 2006

A method is proposed which can facilitate parallel computations of particle transport in complex environments, such as urban landscapes. A two stage‐approach is used, where in the first stage, physical simulations of various aerosol release scenarios are conducted on a high‐performance distributed computing facility, such as a Beowulf cluster or a computing grid, and stored in a database as a set of transfer probabilities. In this stage, the method provides a partially decoupled parallel implementation of a tightly coupled physical system. In the second stage, various aerosol release scenarios can be analysed in a timely manner, using obtained probability distributions and a simpler stochastic simulator, which can be executed on a commodity computer, such as a workstation or a laptop. The method presents a possibility of solving the inverse problem of determining the release source from the available deposition data. Using the proposed approach and developed graphical tools, a case of aerosol dispersion in a typical urban landscape has been studied. A considerable speedup of analysis time for different aerosol dispersion scenarios has been demonstrated. The method is appropriate for the development of express risk analysis systems. Copyright © 2006 John Wiley & Sons, Ltd.
Cytotoxicity of partial‐stabilized cement
Authors: Wang Wen‐Hsi , Lin Feng‐Huei , Lee Yuan‐Ling , Lin Chun‐Pin
Published: November 2006

Partial‐stabilized cement (PSC) is a kind of modified calcium silicate cement used for root‐end surgery. Minor transition metal elements Co, Cr, and Zn were added for enhancing the setting property of to PSC. In our previous study, minor transition metal additions greatly improved the setting property of PSC. However, the concern of metal toxicity was raised, as the material would be used in the human body. In this study, we evaluated the cytotoxicity of PSC in comparison with mineral trioxide aggregate (MTA), which is one of the commercialized materials used for dental root‐end filling. Primary osteoblast cell was used as the target cell. Cell proliferation, cytotoxicity, viability, function, and senescence were analyzed. The cytotoxicity of the PSC‐Zn group (PSC with Zn addition) was similar to that of MTA. PSC‐Zn is not only nontoxic at the cellular level but also has adequate mechanical property, which makes it a potential root‐end filling material for apical surgery. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Increased osteoblast adhesion on nanograined hydroxyapatite and tricalcium phosphate containing calcium titanate
Authors: Ergun Celaletdin , Liu Huinan , Halloran John W. , Webster Thomas J.
Published: November 2006

Depending on the coating method utilized and subsequent heat treatments (such as through the use of plasma‐spray deposition), inter‐diffusion of atomic species across titanium (Ti) and hydroxyapatite (HA) coatings may result. These events may lead to structural and compositional changes that consequently cause unanticipated HA phase transformations which may clearly influence the performance of an orthopedic implant. Thus, the objective of the present in vitro study was to compare the cytocompatibility properties of chemistries that may form at the Ti:HA interface, specifically HA, tricalcium phosphate (TCP), HA doped with Ti, and those containing calcium titanate (CaTiO3). In doing so, results of this study showed that osteoblast (bone‐forming cells) adhesion increased with greater CaTiO3 substitutions in either HA or TCP. Specifically, osteoblast adhesion on HA and TCP composites with CaTiO3 was almost 4.5 times higher than that over pure HA. Material characterization studies revealed that enhanced osteoblast adhesion on these compacts may be due to increasing shrinkage in the unit lattice parameters and decreasing grain size. Although all CaTiO3 composites exhibited excellent osteoblast adhesion results, Ca9HPO4(PO4)5OH phase transformation into TCP/CaTiO3 increased osteoblast adhesion the most; because of these reasons, these materials should be further studied for orthopedic applications. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2006
Combined radiofrequency ablation and doxorubicin‐eluting polymer implants for liver cancer treatment
Authors: Weinberg Brent D. , Blanco Elvin , Lempka Scott F. , Anderson James M. , Exner Agata A. , Gao Jinming
Published: November 2006

Previously, biodegradable polymer implants (polymer millirods) to release chemotherapeutic agents directly into tumors have been developed. The purpose of this study is to evaluate local drug distribution from these implants in liver tumors treated with radiofrequency (RF) ablation and determine if the implants provide a therapeutic improvement over RF ablation alone. Cylindrical implants were fabricated using 65% poly(D,L‐lactide‐co‐glycolide) (PLGA), 21.5% NaCl, and 13.5% doxorubicin. Control or drug‐containing millirods were implanted inside VX2 liver tumors (11 mm diameter) in rabbits after RF ablation. Therapeutic efficacy was assessed 4 and 8 days after treatment using tumor size, histology, and fluorescence measurement of drug distribution. Tumors in both test groups recurred at the boundary of the ablated region. Therapeutic doxorubicin concentrations were found in more than 80% of the ablated area, but concentrations declined rapidly at the boundary between normal and ablated tissue. This region was characterized by a developing fibrous capsule with resolving inflammation, which restricted drug transport out of the ablated zone. The intratumoral doxorubicin implants delivered high concentrations of drug within the ablated region but only limited amounts outside the ablation zone. Future studies will focus on overcoming the fibrotic transport barrier and enhancing drug delivery to the periphery of the ablation region to prevent tumor progression. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Fibrinogen adsorption and platelet lysis characterization of fluorinated surface‐modified polyetherurethanes
Authors: Massa T.M. , McClung W.G. , Yang M.L. , Ho J.Y.C. , Brash J.L. , Santerre J.P.
Published: November 2006

A polyetherurethane (PU) was modified using fluorinated surface‐modifying macromolecules (SMMs). A double radiolabel method was used simultaneously to measure the number of adhered platelets (51Cr) and the quantity of adsorbed Fg (125I), in a cone‐and‐plate instrument. The objectives were to determine if adsorbed Fg levels correlated to platelet adhesion on the surfaces, and to assess if any reductions in platelet adhesion for the SMM‐treated surfaces resulted from surface‐induced platelet lysis, rather than changes directly related to lower platelet activation and attachment on the novel surfaces. Platelet lysis was determined from lactate dehydrogenase (LDH) and unbound 51Cr released into plasma isolated from whole blood exposed to test materials. The corresponding Fg adsorption, evaluated under the same platelet adhesion conditions, did not account for the reduced platelet adhesion on the treated surfaces. LDH and 51Cr platelet release were very low and indicated no statistically significant differences between the materials. It was therefore concluded that platelet lysis did not contribute to the reduction in platelet adhesion characteristic observed on the SMM‐treated surfaces. More importantly, the work emphasizes that the platelet activation cannot be inferred to by assessing the quantity of fibrinogen as is commonly done in the literature. The finding suggests a much more complex mechanism of action for the SMM surface modifiers. On‐going work is investigating other Fg parameters such as protein binding affinity and protein conformational state in order to establish the mechanism by which the fluorinated surface modifiers may be reducing platelet adhesion via intermediary changes in initial protein adsorption. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Inflammatory response to titanium surfaces with fibrinogen and catalase coatings: An in vitro study
Authors: Göransson A. , Gretzer C. , Tengvall P. , Wennerberg A.
Published: November 2006

The aim of the present study was to evaluate the possibility to modulate the early inflammatory response in vitro by coating titanium surfaces with candidate proinflammatory (fibrinogen coated turned titanium “Fib”) and antiinflammatory proteins (catalase on top of fibrinogen coated turned titanium “Cat”). Additionally, turned titanium surfaces (Ti) were used as controls. The discs were incubated with human mononuclear cells. Adhered cells were investigated with respect to number, viability, differentiation (acute marker 27E10 vs. chronic marker RM3/1), and cytokine production (TNF‐α and IL‐10), after 24 and 72 h. The results indicated that it is possible to modulate the inflammatory response with protein coatings. However, the strongest inflammatory response, indicated by increased number of adhered cells and release of pro and antiinflammatory mediators, was induced by Cat. Furthermore, the cytokine production on this surface was not sensitive to LPS stimulation. Differentiation measured as the expression of the chronic cell surface marker, dominated after 72 h for all surface modifications and Cat displayed an increased number compared to the others. A decrease in the total number of adhered cells and amounts of TNF‐α were observed on all surfaces over time. The cell viability was, in general, high for all tested surfaces. In conclusion, the study proved it possible to influence the early inflammatory response in vitro by immobilizing protein coatings to titanium surfaces. However, the catalase surface demonstrated the strongest inflammatory response, and the possibility to selectively use the potent antiinflammatory capacity of catalase needs to be further evaluated. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Synthesis, characterization, and in vitro activity of antibiotic releasing polyurethanes to prevent bacterial resistance
Authors: Ruggeri V. , Francolini I. , Donelli G. , Piozzi A.
Published: November 2006

Central venous catheters are a major cause of nosocomial bloodstream infections. Different attempts have been made to incorporate antimicrobial agents into catheters, particularly directed at the surface‐coating of devices. To facilitate the antimicrobial adsorption, various cationic surfactants, which however showed several problems, have been used. On the other hand, impregnated catheters with only antimicrobials have demonstrated a short‐term duration due to the difficulties to deliver the drug slowly. Thus, in order to obtain high antimicrobial‐polymer affinity we synthesized or modified polyurethanes to introduce different functional groups. Polymers were loaded with two antibiotics, cefamandole nafate and rifampin (RIF), chosen for both their functional groups and their action spectrum. The in vitro release behavior showed that the elution of drugs depended on the matrix hydrophilicity and on the antibiotic–polymer and antibiotic–antibiotic interactions. To increase the amount of drug released, polyethylene glycol (PEG) used as a pore forming agent at different molecular weights was incorporated in the polymer bulk with antibiotics. As for the in vitro antimicrobial activity of matrices, assessed by Kirby‐Bauer test, it was seen that antibiotics released from various formulations inhibited the bacterial growth and exerted a synergistic effect when both were present. In particular, PEG10000‐containing polymer was active against the RIF‐resistant S. aureus strain up to 23 days. These results suggest that the combined entrapping of antibiotics and pore formers in these novel polymer systems could be promising to prevent the bacterial colonization and to control the emergence of bacterial resistance. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Electrospun fibrinogen: Feasibility as a tissue engineering scaffold in a rat cell culture model
Authors: McManus Michael C. , Boland Eugene D. , Simpson David G. , Barnes Catherine P. , Bowlin Gary L.
Published: November 2006

Fibrinogen has a well‐established tissue engineering track record because of its ability to induce improved cellular interaction and scaffold remodeling compared to synthetic scaffolds. While the feasibility of electrospinning fibrinogen scaffolds of submicron diameter fibers and their mechanical properties have been demonstrated, in vitro cellular interaction has not yet been evaluated. The goal of this study was to demonstrate, based on cellular interaction and scaffold remodeling, that electrospun fibrinogen can be used successfully as a tissue engineering scaffold. Electrospun fibrinogen scaffolds were disinfected, seeded with neonatal rat cardiac fibroblasts, and cultured for 2, 7, and 14 days. Cultures were treated to regulate scaffold degradation by either supplementing serum‐containing media with aprotinin or crosslinking the scaffolds with glutaraldehyde vapor. Biocompatibility was assessed through a WST‐1 cell proliferation assay. Postculture scaffolds were evaluated by scanning electron microscopy and histology. Cell culture demonstrated that fibroblasts readily migrate into and remodel electrospun fibrinogen scaffolds with deposition of native collagen. Supplementation of culture media with different concentrations of aprotinin‐modulated scaffold degradation in a predictable fashion, but glutaraldehyde vapor fixation was less reliable. Based on the observed cellular interactions, there is tremendous potential for electrospun fibrinogen as a tissue engineering scaffold. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Layer‐by‐layer assembly of polyelectrolyte films improving cytocompatibility to neural cells
Authors: Wu Zhong‐Rong , Ma Jun , Liu Bing‐Fang , Xu Qun‐Yuan , Cui Fu‐Zhai
Published: November 2006

The using of layer‐by‐layer assembly polyelectrolyte (PE) films has been suggested as a new versatile technique for surface modification aimed at tissue engineering and cell‐based chips. In this study, we investigated the surface morphology of the hyaluronic acid (HA)‐based PE films deposited on the amino‐functionalized glass slides using atomic force microscopy. These thin films (bilayer number <9) were measured to have nanoscale roughness ranging from 10 to 100 nm. Then the primary hippocampal and cortical neural cells were cultured on the PE films, respectively. After 5 days of culturing, the cytocompatibility to neural cells was evaluated by cellular morphology, neurite outgrowth, and microtubule‐associated protein 2 expressions. From the present results, the HA‐based PE films were found to be able to support neural cell adhesion and neurite development, especially for the polycation‐ending films. It is suggested these HA‐based multilayer PE films or similar build‐ups could thus be used in the future as a way to modify surfaces for nerve scaffolds and neuron‐based chips. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2007