bluuebunny/crossref_metadata_2025 huggingface dataset:
REPLACE: A Strategy for Iterative Design of Cyclin‐Binding Groove Inhibitors
Authors: Andrews Martin J. I. , Kontopidis George , McInnes Campbell , Plater Andy , Innes Lorraine , Cowan Angela , Jewsbury Philip , Fischer Peter M.
Published: October 2006

We describe a drug‐design strategy termed REPLACE (REplacement with Partial Ligand Alternatives through Computational Enrichment) in which nonpeptidic surrogates for specific determinants of known peptide ligands are identified in silico by using a core peptide‐bound protein structure as a design anchor. In the REPLACE application example, we present the effective replacement of two critical binding motifs in a lead protein–protein interaction inhibitor pentapeptide with more druglike phenyltriazole and diphenyl ether groups. These were identified through docking of fragment libraries into the volume of the cyclin‐binding groove of CDK2/cyclin A vacated through truncation of the inhibitor peptide‐binding determinants. Proof of concept for this strategy was obtained through the generation of potent peptide–small‐molecule hybrids and by the confirmation of inhibitor‐binding modes in X‐ray crystal structures. This method therefore allows nonpeptide fragments to be identified without the requirement for a high‐sensitivity binding assay and should be generally applicable in replacing amino acids as individual residues or groups in peptide inhibitors to generate pharmaceutically acceptable lead molecules.
Natural and Non‐natural Antenna Chromophores in the DNA Photolyase from Thermus Thermophilus
Authors: Klar Tobias , Kaiser Gebhard , Hennecke Ulrich , Carell Thomas , Batschauer Alfred , Essen Lars‐Oliver
Published: October 2006

X‐ray crystallographic and functional analysis of the class I DNA photolyase from Thermus thermophilus revealed the binding of flavin mononucleotide (FMN) as an antenna chromophore. The binding mode of FMN closely coincides with the binding of a deazaflavin‐like chromophore in the related class I DNA photolyase from Anacystis nidulans. Compared to the R46E mutant, which lacks a conserved arginine in the binding site for the antenna chromophore, the FMN‐comprising holophotolyase exhibits an eightfold higher activity at 450 nm. The facile incorporation of the flavin cofactors 8‐hydroxy‐deazariboflavin and 8‐iodo‐8‐demethyl‐riboflavin into the binding site for the antenna chromophore paves the way for wavelength‐tuning of the activity spectra of DNA photolyases by using synthetic flavins.
A Class of Benzenoid Chemicals Suppresses Apoptosis in C. elegans
Authors: Kokel David , Xue Ding
Published: October 2006

Benzene is a human carcinogen that might act through both genotoxic and nongenotoxic mechanisms to promote tumorigenesis. The genotoxic effects of benzene are well established, however, its potential nongenotoxic roles in carcinogenesis are poorly understood. We find that benzene suppresses somatic apoptosis in C. elegans; this suggests a potential nongenotoxic mechanism by which this chemical might promote tumorigenesis. We find that two other benzenoid chemicals, biphenyl and toluene, also inhibit apoptosis in C. elegans. Notably, these chemicals are suspected carcinogens in mammals; this suggests that a subclass of benzenoid chemicals might promote tumorigenesis by suppressing apoptosis. A benzene metabolite, 1,4‐benzoquinone, can directly inhibit the activity of caspase‐3; this suggests a general molecular mechanism by which benzenoid chemicals might suppress apoptosis. These findings suggest that C. elegans is an excellent alternative animal model for studying the antiapoptotic activity of tumor‐promoting chemicals and for identifying in vivo targets of these chemicals.
Directed Evolution of a Non‐Heme‐Iron‐Dependent Extradiol Catechol Dioxygenase: Identification of Mutants with Intradiol Oxidative Cleavage Activity
Authors: Schlosrich Janne , Eley Kirstin L. , Crowley Patrick J. , Bugg Timothy D. H.
Published: October 2006

The non‐heme‐iron(II)‐dependent extradiol catechol dioxygenases catalyse the oxidative cleavage of substituted catechols found on bacterial aromatic degradation pathways. The reaction mechanism of the extradiol dioxygenases is believed to proceed through the same proximal hydroperoxide intermediate as the iron(III)‐dependent intradiol catechol dioxygenases. Directed evolution was carried out on members of the class III extradiol catechol dioxygenases, by using 1) error‐prone polymerase chain reaction, 2) a primer‐based cross‐over method; the mutant dioxygenases were then screened for their ability to process a range of substituted catechols. Several mutant enzymes were found to show higher activity towards certain substituted catechols, including 4‐chlorocatechol, and higher affinity for the iron(II) cofactor. Two mutants isolated from error‐prone PCR of Escherichia coli MhpB (mutants R215W and K273R) were found to produce a mixture of extradiol and intradiol cleavage products, as detected by GC‐MS and 1H NMR spectroscopy. The residue corresponding to K273 in protocatechuate 4,5‐dioxygenase (LigAB), Val244, is located approximately 12 Å from the iron(II) centre, but close to the putative dioxygen channel; R215 is found on a sequence loop not present in LigB.
Routine clinical use of alemtuzumab in patients with heavily pretreated B‐cell chronic lymphocytic leukemia
Authors: Fiegl Michael , Falkner Andreas , Hopfinger Georg , Brugger Stefan , Zabernigg August , Bauer Franz , Haslbauer Ferdinand , Demirtas Dita , Grossschmidt Peter , Tatzreiter Georg , Gastl Günther , Greil Richard ,   The Austrian Collaborative Study Group on Alemtuzumab in Chronic Lymphocytic Leukemia
Published: October 2006

BACKGROUND.

In previous studies, alemtuzumab demonstrated considerable activity in patients with previously treated B‐cell chronic lymphocytic leukemia (CLL), including fludarabine‐refractory disease. In this retrospective study, the authors evaluated the benefit of alemtuzumab monotherapy in unselected patients with advanced, previously treated CLL who received treatment in the routine clinical setting.

METHODS.

Data were collected from 115 consecutive patients who received alemtuzumab therapy at 25 participating centers in Austria. Patients received a median of 3 prior lines of therapy (range, 1–11 prior lines of therapy), and 59% had fludarabine‐refractory disease. Alemtuzumab was administered intravenously or subcutaneously with a planned schedule of 30 mg 3 times per week for up to 12 weeks. Patients received valacyclovir and trimethoprim/sulfamethoxazole for antiinfective prophylaxis.

RESULTS.

The overall response rate was 23%, with complete responses achieved in 5% of patients. Stable disease (SD) was achieved in 36% of patients. After a median follow‐up of 17.5 months, the median overall survival (OS) was 20.2 months for all patients. A multivariate Cox regression analysis that included pretreatment baseline characteristics, response to therapy, and cumulative dose of alemtuzumab indicated that bulky lymphadenopathy, the administration of ≥3 previous therapies, and lack of response to alemtuzumab remained significant independent risk factors for inferior OS. The median OS had not been reached for responding patients. The median OS was 29.5 months for patients with SD and 10.8 months for patients with progressive disease.

CONCLUSIONS.

The broad use of alemtuzumab in the routine clinical practice setting is feasible and active in unselected patients with pretreated CLL, and the current results confirmed the activity and safety of this agent, as reported in previously published clinical studies. Cancer 2006. © 2006 American Cancer Society.
Lanreotide autogel every 6 weeks compared with Lanreotide microparticles every 3 weeks in patients with well differentiated neuroendocrine tumors
Authors: Bajetta Emilio , Procopio Giuseppe , Catena Laura , Martinetti Antonia , De Dosso Sara , Ricci Sergio , Lecchi Alberto S. , Boscani Paolo F. , Iacobelli Stefano , Carteni Giacomo , De Braud Filippo , Loli Paola , Tartaglia Andreas , Bajetta Roberto , Ferrari Leonardo
Published: October 2006

BACKGROUND.

The noninferiority of a 6‐week dosing schedule of lanreotide Autogel (Lan ATG) at a dose of 120 mg compared with a 3‐week dosing schedule of lanreotide microparticles (Lan MP) at a dose of 60 mg was investigated in patients with neuroendocrine tumors (NET).

METHODS.

Patients who had sporadic, well differentiated NET with a low grade of malignancy were recruited for this open‐label, Phase III, multicenter trial. Patients were randomized to receive either 3 deep subcutaneous injections of Lan ATG (120 mg, every 6 weeks) or 6 intramuscular injections of Lan MP (60 mg, every 3 weeks). Tumor markers, tumor size, and symptoms were assessed between baseline and Week 18. Success was classified as a response that ranged from disappearance to an increase <25% in tumor marker, tumor size, or symptom frequency.

RESULTS.

Sixty patients were randomized, and 46 patients completed the study. Both for tumor markers and for tumor size, Lan ATG was not inferior to Lan MP (55% and 59% of patients responded on tumor markers, respectively; 68% and 66% of patients responded on tumor size, respectively). There were too few symptomatic patients to compare carcinoid symptoms. Both treatments were tolerated well, and no safety concerns were identified.

CONCLUSIONS.

Lan ATG at a dose of 120 mg every 6 weeks was as effective for controlling NET as Lan MP at a dose of 60 mg every 3 weeks. Cancer 2006. © 2006 American Cancer Society.
Role of intraoperative cytology combined with histology in detecting continuous and skip type intraductal cancer existence for intraductal papillary mucinous carcinoma of the pancreas
Authors: Eguchi Hidetoshi , Ishikawa Osamu , Ohigashi Hiroaki , Sasaki Yo , Yamada Terumasa , Nakaizumi Akihiko , Uehara Hiroyuki , Takenaka Akemi , Kasugai Tsutomu , Imaoka Shingi
Published: October 2006

BACKGROUND.

Intraductal papillary mucinous neoplasm (IPMN) is a recently discovered pancreatic tumor that has continuous or discontinuous (skip) lesions. Recent reports suggest a higher frequency of cancer recurrence in the remnant pancreas after surgical resection of IPMN. It is therefore important to precisely detect intraductal cancer extension and skip lesions when resecting IPMN.

METHODS.

Both intraoperative histologic examination of the surgical margin and cytologic examination of the pancreatic juice from each pancreatic segment (head, body, or tail) were performed on 43 IPMN patients. In addition to the preoperatively planned resection, 1 or 2 pancreatic segment(s) were additionally resected if the pancreatic juice tested positive in cytology. When a surgical margin was positive but the cytology in the remaining segment was negative, a subsegment (2‐cm slice in width) was additionally resected until a negative margin was confirmed.

RESULTS.

Twenty‐five patients (58%) demonstrated negative results in both histology and cytology obtained from the segment(s) that were not initially intended to be removed. In contrast to the preoperative estimation, 5 patients were found to have a positive surgical margin and negative cytology, 5 patients demonstrated a negative surgical margin and positive cytology, and 8 patients demonstrated a positive surgical margin and positive cytology. Investigations of the resected specimens revealed that 8 patients (19%) had skip lesions in addition to the main lesion. Logistic regression analysis revealed that patients with a dilated main pancreatic duct, or those with cancerous lesions in the main tumors, were at high risk for positive histology and/or cytology.

CONCLUSIONS.

Using intraoperative frozen‐section histology and pancreatic juice cytology, 18 out of 43 patients in the current study (42%) required additional resection of the pancreas. A necessary and sufficient range of resection should be determined by intraoperative examination. Cancer 2006. © 2006 AmericanCancer Society.
Study of free‐surface seepage problems using hypersingular equations
Authors: Chen Jeng‐Tzong , Hsiao Chia‐Chun , Chiu Yi‐Ping , Lee Ying‐Te
Published: October 2006

Free‐surface boundary is not only unknown in a priori but also the boundary conditions are overspecified. In this paper, the Laplace problem with overspecified boundary conditions on the free surface is solved by using the hypersingular equation instead of singular equation used conventionally in boundary element method. The free surface can be determined using an iterative procedure starting from an initial guess. By introducing the hypersingular equation, the convergence rate of free surface can be accelerated. Finally, numerical examples including rectangular dams and canals were demonstrated and were compared with others to show the validity of the present method. Copyright © 2006 John Wiley & Sons, Ltd.
Application of a generic domain‐decomposition strategy to solve shell‐like problems through 3D BE models
Authors: Araújo F. C. , Silva K. I. , Telles J. C. F.
Published: October 2006

Efficient integration algorithms and solvers specially devised for boundary‐element procedures have been established over the last two decades. A good deal of quadrature techniques for singular and quasi‐singular boundary‐element integrals have been developed and reliable Krylov solvers have proven to be advantageous when compared to direct ones, also in case of non‐Hermitian matrices. The former has implied in CPU‐time reduction during the assembling of the system of equations and the latter in its faster solution. Here, a triangular polar co‐ordinate transformation and the Telles co‐ordinate transformation are employed separately and combined to develop the matrix‐assembly routines (integration routines). In addition, the Jacobi‐preconditioned Biconjugate Gradient solver (J‐BiCG) is used along with a generic substructuring boundary element algorithm. Thus, solution CPU time and computer memory can be considerably reduced. Discontinuous boundary elements are also included to simplify the coupling of the BE models (substructures). Numerical experiments involving 3D thin‐walled domains (shell‐like structural elements) are carried out to show the performance of the computer code with respect to accuracy and efficiency of the system solution. Precision, CPU‐time and potential applications of the BE code developed are commented upon. Copyright © 2006 John Wiley & Sons, Ltd.
Modelling radiation and moisture content in fire spread
Authors: Ferragut L. , Asensio M. I. , Monedero S.
Published: October 2006

A numerical method is developed for fire spread simulation modelling. The model is a two‐dimensional one which takes into account moisture content and radiation. We consider the combustion of a porous solid, where a simplified energy conservation equation is applied. The effect of the vegetation moisture and endothermic pyrolysis is incorporated in the model by means of a multivalued function representing the enthalpy. Some of the three‐dimensional effects are incorporated in the model, i.e. heat losses in the vertical direction and non‐local radiation from the flame above the vegetal layer. Also the radiation model allows to cope with wind and slope effects. The approximate solution is obtained using a finite element method. A semi‐implicit Euler algorithm in time is applied. The resolution of the multivalued operator is done using the Yosida approximation of a perturbed multivalued operator. The characteristic method combined with a discrete ordinate method is used to solve the radiation equation. Finally, several representative examples are solved and compared with experimental data. Copyright © 2006 John Wiley & Sons, Ltd.
Estimating spatial and parameter error in parameterized nonlinear reaction–diffusion equations
Authors: Carnes B. R. , Carey G. F.
Published: October 2006

A new approach is proposed for the a posteriori error estimation of both global spatial and parameter error in parameterized nonlinear reaction–diffusion problems. The technique is based on linear equations relating the linearized spatial and parameter error to the weak residual. Computable local element error indicators are derived for local contributions to the global spatial and parameter error, along with corresponding global error indicators. The effectiveness of the error indicators is demonstrated using model problems for the case of regular points and simple turning points. In addition, a new turning point predictor and adaptive algorithm for accurately computing turning points are introduced. Copyright © 2006 John Wiley & Sons, Ltd.
Numerically evaluated displacement and stress solutions for a 3D viscoelastic half space subjected to a vertical distributed surface stress loading using the Radon and Fourier transforms
Authors: Adolph Marco , Mesquita Euclides , Carvalho Edson Rodrigues , Romanini Edivaldo
Published: October 2006

In this article a numerical solution for a 3D isotropic, viscoelastic half‐space subjected to vertical rectangular surface stress loading of constant amplitude is evaluated with the aid of the Radon and Fourier integral transforms. Dynamic displacement and stress fields are computed for the half‐space surface as well as for points inside the domain. The analysis is performed in the frequency domain. Viscoelastic effects are incorporated by means of the elastic–viscoelastic correspondence principle. The equations of motion are solved in the Radon–Fourier transformed domain. Inverse transformations to the physical domain are accomplished numerically. The scheme used to perform the numerical inverse transformations is addressed. The solution is validated by comparison with results available in the literature. A sample of original dynamic results for displacement and stress fields for the 3D half‐space is furnished. Copyright © 2006 John Wiley & Sons, Ltd.
A comparative study of algorithms for minimal cycle bases for efficient force method of frame analysis
Authors: Kaveh A. , Fazli H.
Published: October 2006

A comparative study of different algorithms is presented for the formation of minimal cycle bases of graphs corresponding to sparse cycle‐member incidence matrices, leading to the formation of sparse flexibility matrices. These algorithms employ concepts from matroids and theory of graphs. The algorithms are compared using the computational time and storage requirements. Proof is constructed for the minimality of the algorithm developed by the first author, and an efficient approach is employed for its implementation. The algorithms are also compared through examples having different topological properties. Copyright © 2006 John Wiley & Sons, Ltd.
A Nyström scheme with rational quadrature applied to edge crack problems
Authors: Englund J.
Published: October 2006

The effects of introducing rational quadrature into a recently developed algorithm for the computation of the stress field in edge‐cracked specimens are studied. The algorithm is based on an integral equation of the second kind which is solved using a Nyström method. Rational quadrature can handle the presence of corners and triple‐junctions in a more accurate manner than can polynomial quadrature. A preconditioner is also included in the scheme. The rational quadrature together with the preconditioner results in a scheme that reduces the number of discretization points needed for a certain accuracy by up to 70% and the number of iterations needed by an iterative solver by up to 50%, compared to a scheme using only polynomial quadrature. For validation, several setups with a single edge crack are studied. Larger setups containing up to 1500 edge cracks are also investigated. Copyright © 2006 John Wiley & Sons, Ltd.
Numerical modelling of diameter errors in slender bar turning with movable support
Authors: Bodi Cui , Rongdi Han
Published: October 2006

Prediction of machining accuracy is an essential prerequisite for optimization of machining processes. In this study, a numerical model is developed to predict diameter errors in slender bar turning operations. Special attention is paid to the effect of the movable support on diameter error during machining process. The proposed model uses a geometric analysis in the machine frame, in which the elastic deflections of the machine‐tool‐part system due to cutting force are studied by finite element method. Further, for the coupling between cutting force and actual depth of cut, iterative calculation is carried out to obtain the coupling value of the cutting depth which provides further accuracy to the prediction. Finally, numerical examples are provided to investigate the effects of mounting method and movable support stiffness on diameter errors. Experimental results show that the developed model has the ability to predict efficiently the diameter errors for slender bar turning operations. Copyright © 2006 John Wiley & Sons, Ltd.
FOXP3+ regulatory T cells: Current controversies and future perspectives
Authors: Banham Alison H. , Powrie Fiona M. , Suri‐Payer Elisabeth
Published: October 2006

Regulatory T cells (Treg) provide protection from autoimmune disease, graft‐versus‐host disease, transplant rejection and overwhelming tissue destruction during infections. Conversely, high Treg numbers enable cancer cells to evade the host immune response. Thus, Treg are seen as an important tool to manipulate the immune response. However, as the immunological community is trying to move this knowledge from mice to humans, contradictory results regarding the number and function of Treg in various diseases are appearing. This problem arises because we cannot clearly define Treg populations on the basis of expression of CD25 and other cell surface markers in humans. This review addresses the utility of the FOXP3 forkhead transcription factor for the identification of Treg populations and summarizes recent data on the expression of FOXP3 in lymphomas. It is crucial to really understand Treg biology before attempting therapies, including (i) the injection of expanded Treg to cure autoimmune disease or prevent graft‐versus‐host disease or (ii) the depletion or inhibition of Treg in cancer therapy. For instance, new data arising from the study of haematological malignancies highlight the additional complexity of systems where malignant cell populations may also be direct Treg targets.
Highly Regioselective Rhenium‐Catalyzed Hydrosilylation of Styrenes
Authors: Zhao Wen‐Guo , Hua Ruimao
Published: October 2006

The addition reaction of silanes to styrenes is efficiently catalyzed by ReBr(CO)5 in toluene heated at 120 °C and selectively affords anti‐Markovnikov adducts in good to high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Electronic ‘Off‐On’ Molecular Switch for Rapid Detection of Thrombin
Authors: Sánchez Josep Lluis Acero , Baldrich Eva , Radi Abd El‐Gawad , Dondapati Srujan , Sánchez Pablo Lozano , Katakis Ioanis , O'Sullivan Ciara K.
Published: October 2006

An electrochemical molecular beacon aptasensor for fast and sensitive assay of thrombin is developed and characterized. A bifunctional derivative of the thrombin‐binding aptamer, 15‐base long with a redox‐active ferrocene moiety and a pendant hexanethiol linker group at the termini of the aptamer strand was immobilized on Au electrode surface. The electrochemical behavior of the aptasensor was studied using cyclic voltammetry (CV), chronoamperometry (CA), chronopotentiometry (CP), square‐wave voltammetry (SWV) and chronopotentiometric stripping analysis (PSA) techniques. Taken together, these experiments support the switch “on” mechanism of the system when the thrombin binds to the immobilized aptamer. The variation of response to the concentration of thrombin, the target protein, was evaluated by square‐wave voltammetry and chronopotentiometric stripping analysis in HEPES buffer solution (pH 8.0, 0.01 M). The aptasensor showed a specific response to thrombin in the range 1.0 to 35 nM with a detection limit of subnanomolar level concentrations. The reaction time, reproducibility, specificity and stability of the aptasensor were also studied.
Electrochemical Study on Synergistic Effect of the Blending of Nano TiO2 and PLA Polymer on the Interaction of Antitumor Drug with DNA
Authors: Song Min , Pan Chao , Li Jingyuan , Wang Xuemei , Gu Zhongze
Published: October 2006

In this report, polylactide (PLA) nanofibers were fabricated with the new strategy of electrospinning that may have some potential prominent application in biomedical areas. Besides, the new nanocomposites produced by the combination of PLA nanofibers with titanium dioxide (TiO2) nanoparticles have been utilized in the biomolecular recognition of antitumor or anticancer drug daunorubicin. Our observations of electrochemical studies indicate that because of the relative large surface area of the blends, the new nano TiO2‐PLA polymer nanocomposites could remarkably increase the detection sensitivity as well as the binding affinity of daunorubicin to DNA, which is also demonstrated in our spectroscopic study. Besides, to further reveal the effect of the new TiO2‐PLA polymer nanocomposites for the biorecognition, the relative influence of nano TiO2 or PLA themselves has also been explored in this study. The results illustrate that the drug molecules and/or DNA could be more readily self‐assembled on the surface of the blends of the nano TiO2‐PLA nanofibers so that the new nanocomposites could efficiently facilitate the relative biorecognition of daunorubicin.
Application of Bacterial Biocathodes in Microbial Fuel Cells
Authors: He Zhen , Angenent Largus T.
Published: October 2006

This review addresses the development and experimental progress of biocathodes in microbial fuel cells (MFCs). Conventional MFCs consist of biological anodes and abiotic cathodes. The abiotic cathode usually requires a catalyst or an electron mediator to achieve high electron transfer, increasing the cost and lowering the operational sustainability. Such disadvantages can be overcome by biocathodes, which use microorganisms to assist cathodic reactions. Biocathodes are feasible in potentiostat‐poised half cells, but only very few studies have investigated them in complete MFCs. The classification of biocathodes is based on which terminal electron acceptor is available. For aerobic biocathodes with oxygen as the terminal electron acceptor, electron mediators, such as iron and manganese, are first reduced by the cathode (abiotically) and then reoxidized by bacteria. Anaerobic biocathodes directly reduce terminal electron acceptors, such as nitrate and sulfate, by accepting electrons from a cathode electrode through microbial metabolism. Biocathodes are promising in MFCs, and we anticipate a successful application after several breakthroughs are made.
A label‐free protein microfluidic array for parallel immunoassays
Authors: Wang Zhan‐Hui , Meng Yong‐Hong , Ying Pei‐Qing , Qi Cai , Jin Gang
Published: October 2006

A label‐free protein microfluidic array for immunoassays based on the combination of imaging ellipsometry and an integrated microfluidic system is presented. Proteins can be patterned homogeneously on substrate in array format by the microfluidic system simultaneously. After preparation, the protein array can be packed in the microfluidic system which is full of buffer so that proteins are not exposed to denaturing conditions. With simple microfluidic channel junction, the protein microfluidic array can be used in serial or parallel format to analyze single or multiple samples simultaneously. Imaging ellipsometry is used for the protein array reading with a label‐free format. The biological and medical applications of the label‐free protein microfluidic array are demonstrated by screening for antibody–antigen interactions, measuring the concentration of the protein solution and detecting five markers of hepatitis B.
Simultaneous electrophoretic analysis of proteins of very high and low molecular weights using low‐percentage acrylamide gel and a gradient SDS‐PAGE gel
Authors: Casas‐Terradellas Eduard , Garcia‐Gonzalo Francesc R. , Hadjebi Ouadah , Bartrons Ramon , Ventura Francesc , Rosa Jose Luis
Published: October 2006

To be able to separate and analyze giant proteins and small proteins in the same electrophoretic gel, we have used a continuous SDS‐PAGE gel formed by the combination of a low‐percentage acrylamide gel and a gradient SDS‐PAGE gel that we have named LAG gel. To get a good resolution for proteins of more than 200 kDa, we used an acrylamide/bisacrylamide ratio of 80:1 in the low‐percentage acrylamide gel. To successfully resolve proteins in the 5–200 kDa range, we used a conventional 6–15% SDS‐PAGE gradient gel with the standard acrylamide/bisacrylamide ratio of 40:1. We show that the LAG system can be successfully used in general applications of SDS‐PAGE electrophoresis such as proteomics and immunobloting techniques. Thus, using this continuous LAG gel, it is possible to simultaneously analyze giant proteins, such as HERC1 and dynein, big proteins like clathrin heavy chain and small proteins like ARF. The LAG system has a good resolution, low cost, and high reproducibility. Moreover, to simultaneously analyze all proteins saves time. All these characteristics, together with the use of a standard apparatus found in any biochemistry laboratory, make the LAG system an easy tool to use.
Life cycle assessment of ISPRA Mark 9 thermochemical cycle for nuclear hydrogen production
Authors: Utgikar Vivek , Ward Bradley
Published: October 2006

The nuclear energy driven thermochemical cycle is one of the potential water‐splitting processes for producing hydrogen, presumed to be the transportation fuel of the future. A life cycle assessment (LCA) of one such system, which utilizes nuclear energy to drive the ISPRA Mark 9 thermochemical cycle, is presented in this paper. The results of the LCA are presented in terms of the emissions of greenhouse gases (CO2‐equivalent) and acid gases (SO2‐equivalent). The contributions of the thermochemical plant to the emissions were determined through the estimation of material and energy requirements for chemical inventory, raw materials consumption and plant fabrication/installation. The greenhouse gas emissions from the system are 2515 g CO2‐equivalent kg−1 H2 produced and acid gas emissions 11.252 g SO2‐equivalent kg−1 H2 produced. A comparison of this hydrogen production route with other routes, including steam reforming of methane and high‐temperature electrolysis, is also presented in the paper. Copyright © 2006 Society of Chemical Industry
A continuous process for the recovery of lactic acid by reactive distillation
Authors: Kumar Rakesh , Nanavati Hemant , Noronha Santosh B , Mahajani Sanjay M
Published: October 2006

Separation and purification of lactic acid from the fermentation broth are difficult because of its non‐volatile nature and the presence of other organic acids. Esterification of lactic acid with methanol followed by hydrolysis of the separated methyl lactate is an effective technique for this purpose. A continuous process for recovery is proposed and various aspects are evaluated through simulation and experiments. In the proposed route, a vapor stream containing methyl lactate is removed from a two‐phase CSTR, used for esterification, operated under boiling conditions. The ester thus separated from the aqueous solution is further hydrolyzed in a reactive distillation column. Continuous removal of the volatile component (i.e. methanol) from the reaction zone increases conversion, thus pure lactic acid is obtained from the bottom of reactive distillation column. The results obtained in the experiments are compared with the simulation results. Further simulation studies were performed to obtain the suitable operating conditions for higher conversion and concentration of lactic acid. Copyright © 2006 Society of Chemical Industry
A modified cellulose adsorbent for the removal of nickel(II) from aqueous solutions
Authors: O'Connell David W , Birkinshaw Colin , O'Dwyer Thomas F
Published: October 2006

A series of adsorption studies was carried out on a glycidyl methacrylate‐ modified cellulose material functionalised with imidazole (Cellulose‐g‐GMA‐Imidazole) to assess its capacity in the removal of Ni(II) ions from aqueous solution. The study sought to establish the effect of a number of parameters on the removal of Ni(II) from solution by the Cellulose‐g‐GMA‐Imidazole. In particular, the influence of initial metal concentration, contact time, solution temperature and pH were assessed. The studies indicated a Ni(II) uptake on the Cellulose‐g‐GMA‐Imidazole sorbent of approximately 48 mg g−1 of nickel from aqueous solution. The adsorption process fitted the Langmuir model of adsorption and the binding process was mildly endothermic. The kinetics of the adsorption process indicated that nickel uptake occurred within 400 min and that pseudo‐second order kinetics best describe the overall adsorption process. Nickel(II) adsorption, recovery and re‐adsorption studies indicated that at highly acidic pH values the adsorbent material becomes unstable, but in the range pH 3–6, the adsorbent is stable and shows limited but significant Ni(II) recovery and re‐adsorption capability. Copyright © 2006 Society of Chemical Industry
Removal of anionic pollutants from groundwaters using Alamine 336: chemical equilibrium modelling
Authors: Bringas Eugenio , San Román M Fresnedo , Ortiz Inmaculada
Published: October 2006

This work reports the study of the chemical equilibrium of the extraction of chromium(VI) anions from groundwaters where other anionic species are present, mainly sulfate and chloride anions, using Alamine 336 as extractant. The analysis was performed working with two different systems: (i) a binary system (sulfate and chloride anions) and, (ii) a tertiary system (chromium, sulfate and chloride anions) with a composition of 9.6–15.4 mol Cr6+ m−3, 5.2–16.7 mol SO42− m−3 and 4.2–13.5 mol Cl− m−3 respectively. A careful experimental design was performed and the data were correlated to the mathematical models obtaining the equilibrium parameters of the extraction reactions in both systems. Copyright © 2006 Society of Chemical Industry
Continuous biotransformation of pyrogallol to purpurogallin using cross‐linked enzyme crystals of laccase as catalyst in a packed‐bed reactor
Authors: Roy J Jegan , Abraham T Emilia
Published: October 2006

Cross‐linked enzyme crystals (CLEC) of laccase were prepared by crystallizing laccase with 75% (NH4)2SO4 and cross‐linking using 1.5% glutaraldehyde. The cross‐linked enzyme crystals were further coated with 1 mmol L−1 β‐cyclodextrin by lyophilization. The lyophilized enzyme crystals were used as such for the biotransformation of pyrogallol to purpurogallin in a packed‐bed reactor. The maximum conversion (76.28%) was obtained with 3 mmol L−1 pyrogallol at a residence time of 7.1 s. The maximum productivity (269.03 g L−1 h−1) of purpurogallin was obtained with 5 mmol L−1 pyrogallol at a residence time of 3.5 s. The productivity was found to be 261.14 g L−1 h−1 and 251.1 g L−1 h−1 when concentrations of 3 mmol L−1 and 7 mmol L−1 respectively were used. The reaction rate of purpurogallin synthesis was maximum (2241.94 mg purpurogallin mg−1 CLEC h−1) at a residence time of 3.5 s, when 5 mmol L−1 pyrogallol was used as the substrate. The catalyst to product ratio calculated for the present biotransformation was 1:2241. The CLEC laccase had very high stability in reuse and even after 650 h of continuous use, the enzyme did not lose its activity. Copyright © 2006 Society of Chemical Industry
Chlorogenic acid is poorly absorbed, independently of the food matrix: A Caco‐2 cells and rat chronic absorption study
Authors: Dupas Coralie , Marsset Baglieri Agnès , Ordonaud Claire , Tomé Daniel , Maillard Marie‐Noëlle
Published: October 2006

According to epidemiologic studies, dietary phenolic antioxidants, such as chlorogenic acid (CQA), could prevent coronary heart diseases and some cancers. Coffee is the main source of CQA in the human diet. The aim of this study was to assess the effect of usual coffee consumption conditions, such as the addition of milk, on CQA bioavailability. Interactions between CQA and milk proteins were shown, using an ultrafiltration technique. These interactions proved to be slightly disrupted during an in vitro digestion process. CQA absorption and bioavailability were then studied in vitro using a Caco‐2 cell model coupled with an in vitro digestion process, and in vivo, in a chronic supplementation study in which rats were fed daily coffee or coffee and milk for 3 weeks. Both experiments showed that CQA absorption under its native form is weak, but unmodified by the addition of milk proteins, and slightly reduced by the addition of Maillard reaction products. These data show that there are some interactions between coffee phenolics and milk proteins, but these have no significant effect on CQA bioavailability from coffee in the rat. CQA is poorly absorbed under its native form in the body, when ingested in a realistic food matrix.
Studies on acrylamide levels in roasting, storage and brewing of coffee
Authors: Lantz Ingo , Ternité Ruediger , Wilkens Jochen , Hoenicke Katrin , Guenther Helmut , van der Stegen Gerrit H. D.
Published: October 2006

The content of acrylamide in coffee reaches a peak early in the roasting process, reflecting occurrence of both formation and destruction of acrylamide during roasting. Levels of acrylamide in the fully roasted product are a small fraction of the peak reached earlier. Glucose and moisture in green coffee do not show a significant correlation with acrylamide in roasted coffee. Pre‐roasting levels of asparagine show a correlation only in Arabica coffee. The main factors affecting the level of acrylamide in roasted coffee appear to be the Arabica/Robusta ratio, with Robusta giving higher levels; time and degree of roast, with both shorter and lighter roasting at the edges of the normal roasting range giving higher levels; storage condition and time, with clear reduction at ambient storage. This storage reduction of acrylamide followed second order reaction kinetics with an activation energy of 73 KJ/mole. The acrylamide in roasted coffee is largely extracted into the brew and stable within usual time of consumption. As these four main factors also substantially affect the sensorial characteristics of the brew, and as modifications of the process have to comply with the consumer‐accepted boundaries of taste profiles, only small effects on the acrylamide level are expected to be achievable.
Determination of bioaccessibility of β‐carotene in vegetables by in vitro methods
Authors: Veda Supriya , Kamath Akshaya , Platel Kalpana , Begum Khyrunnisa , Srinivasan Krishnapura
Published: October 2006

The in vitro method in use for the determination of β‐carotene bioaccessibility involves simulated gastrointestinal digestion followed by ultracentrifugation to separate the micellar fraction containing bioaccessible β‐carotene and its quantitation. In this study, the suitability of two alternatives viz., membrane filtration and equilibrium dialysis were examined to separate the micellar fraction. Values of β‐carotene bioaccessibility obtained with the membrane filtration method were similar to those obtained by the ultracentrifugation method. Equilibrium dialysis was found not suitable for this purpose. Among the vegetables analyzed, fenugreek leaves had the highest content of β‐carotene (9.15 mg/100 g), followed by amaranth (8.17 mg/100 g), carrot (8.14 mg/100 g) and pumpkin (1.90 mg/100 g). Percent bioaccessibility of β‐carotene ranged from 6.7 in fenugreek leaves to 20.3 in carrot. Heat treatment of these vegetables by pressure cooking and stir‐frying had a beneficial influence on the bioaccessibility of β‐carotene from these vegetables. The increase in the percent bioaccessibility of β‐carotene as a result of pressure‐cooking was 100, 48 and 19% for fenugreek leaves, amaranth and carrot, respectively. Stir‐frying in presence of a small quantity of oil led to an enormous increase in the bioaccessibility of β‐carotene from these vegetables, the increase being 263% (fenugreek leaves), 192% (amaranth leaves), 63% (carrot) and 53% (pumpkin).
A regularized force‐based beam element with a damage–plastic section constitutive law
Authors: Addessi Daniela , Ciampi Vincenzo
Published: October 2006

A new beam finite element is presented, with a generalized section constitutive law based on damage mechanics and plasticity, to analyse the cyclic structural response of plane frames. Both displacement‐based and force‐based (FB) approaches are used and compared, to demonstrate the significant advantages of the FB formulation in the presence of material non‐linearity. In order to overcome the analytical problems and the pathological mesh dependency of the numerical response in the presence of strain‐softening post‐peak behaviour, a classical non‐local regularization procedure is adopted first, based on the integral definition of the associated variable governing the damaging evolution process. Subsequently, for the FB element a new simple regularization technique is proposed based on a selected integration procedure along the element length, which predefines the location of the Gauss points in the beam region, where the localization phenomena take place. As for the other computational aspects, an iterative element state determination is adopted for the FB formulation and a local predictor–corrector algorithm is used to solve the incremental evolution problems of the damage and plastic internal variables. Finally, some examples are shown on simple beams and frames, subjected to monotonically increasing and cyclic loading conditions. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and properties of fluorinated polyimides from a new unsymmetrical diamine: 1,4‐(2′‐Trifluoromethyl‐4′,4′‐diaminodiphenoxy)benzene
Authors: Shao Yu , Li Yan‐Feng , Zhao Xin , Wang Xiao‐Long , Ma Tao , Yang Feng‐Chun
Published: October 2006

A new aromatic, unsymmetrical ether diamine with a trifluoromethyl pendent group, 1,4‐(2′‐trifluoromethyl‐4′,4″‐diaminodiphenoxy)benzene, was successfully synthesized in three steps with hydroquinone as a starting material and polymerized with various aromatic tetracarboxylic acid dianhydrides, including 4,4′‐oxydiphthalic anhydride, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride, 2,2′‐bis(3,4‐dicarboxyphenyl)‐hexafluoropropane dianhydride, and pyromellitic dianhydride, via a conventional two‐step thermal or chemical imidization method to produce a series of fluorinated polyimides. The polyimides were characterized with solubility tests, viscosity measurements, IR, 1H NMR, and 13C NMR spectroscopy, X‐ray diffraction studies, and thermogravimetric analysis. The polyimides had inherent viscosities of 0.56–0.77 dL/g and were easily dissolved in both polar, aprotic solvents and common, low‐boiling‐point solvents. The resulting strong and flexible polyimide films exhibited excellent thermal stability, with decomposition temperatures (at 5% weight loss) above 522 °C and glass‐transition temperatures in the range of 232–272 °C. Moreover, the polymer films showed outstanding mechanical properties, with tensile strengths of 74.5–121.7 MPa, elongations at break of 6–13%, and initial moduli of 1.46–1.95 GPa, and good dielectric properties, with low dielectric constants of 1.82–2.53 at 10 MHz. Wide‐angle X‐ray diffraction measurements revealed that these polyimides were predominantly amorphous. These outstanding combined features ensure that the polymers are desirable candidate materials for advanced microelectronic applications. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6836–6846, 2006
Melt compounding of polylactide/organoclay: Structure and properties of nanocomposites
Authors: Pluta Miroslaw
Published: October 2006

A Brabender mixer was used to deagglomerate and disperse organomodified montmorillonite Cloisite® 30B (3 wt %) in polylactide (PLA) matrix to obtain nanocomposite systems. The influence of compounding conditions such as blending time (6.5, 10, 20, and 30 min) and compression molding on the nanostructure of nanocomposites was investigated. Molecular weight changes of the PLA matrices induced by melt compounding were determined. Good rheological behavior of the PLA during melt blending with Cloisite® 30B was observed. Prolongation of the blending process improved homogenization of the nanocomposites with the formation of more intercalated and exfoliated structures as revealed by transmission electron microscopy (TEM) and X‐ray analysis. Some orientation of the silicate nanoplatelets induced by compression molding of the nanocomposites was revealed by TEM. It was found that an increase of dispersion degree of the silicate layers modified pronouncedly the physical properties of nanocomposites through an increase of thermal stability as revealed by the thermogravimetric analysis, a decrease of crystallizability of the PLA matrix during melt‐crystallization and upon heating from the glassy, amorphous state. Rheological properties of the nanocomposites determined during dynamic frequency sweep appeared to be very sensitive to the nanostructure evolution. Moreover, the scanning electron microscopy and light microscopy investigations showed the presence of the micron‐size inorganic contaminations in the nanocomposites originating from organoclay Cloisite® 30B. These inclusions were resistive to deagglomeration during melt processing. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3392–3405, 2006
Superdrawing of polytetrafluoroethylene nascent powder by solid‐state coextrusion
Authors: Sawai Daisuke , Watanabe Daisuke , Morooka Naoyuki , Kuroki Haruka , Kanamoto Tetsuo
Published: October 2006

A film of nascent powder of polytetrafluoroethylene (PTFE), compacted below the ambient melting temperature (Tm, 335 °C), was drawn by two‐stage draw techniques consisting of a first‐stage solid‐state coextrusion followed by a second‐stage solid‐state coextrusion or tensile draw. Although the ductility of extrudates was lost for the second‐stage tensile draw at temperatures above 150 °C due to the rapid decrease in strength, as previously reported, the ductility of extrudates increased with temperature even above 150 °C when the second‐stage draw was made by solid‐state coextrusion, reflecting the different deformation flow fields in a free space for the former and in an extrusion die for the latter. Thus, a powder film initially coextruded to a low extrusion draw ratio (EDR) of 6–20 at 325 °C was further drawn by coextrusion to EDRs up to ∼︁400 at 325–340 °C, near the Tm. Extremely high chain orientation (fc = 0.998 ± 0.001), crystallinity (96.5 ± 0.5)%, and tensile modulus (115 ± 5 GPa at 24 °C, corresponding to 73% of the X‐ray crystal modulus) were achieved at high EDRs. Despite such a morphological perfection and a high modulus, the tensile strength of a superdrawn tape, 0.48 ± 0.03 GPa, was significantly low when compared with those (1.4–2.3 GPa) previously reported by tensile drawing above the Tm. Such a low strength of a superdrawn, high‐modulus PTFE tape was ascribed to the low intermolecular interaction of PTFE and the lack of intercrystalline links along the fiber axis, reflecting the initial chain‐extended morphology of the nascent powder combined with the fairly high chain mobility associated with the crystal/crystal transitions at around room temperature. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3369–3377, 2006