bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of the Langmuir Formalism for Modeling the Adsorption Isotherms of Proteins and Polyelectrolytes in Simulations of Ion Exchange Chromatography
Authors: Jozwik M. , Kaczmarski K. , Freitag R. 
Published: November 2005

AbstractThe adsorption behavior of two cationic proteins (cytochrome c and α‐chymotrypsinogen) and one synthetic polycation (poly(diallylmethylammonium chloride), polyDADMAC) was investigated on a porous particle based and a monolithic cation exchanger column. All isotherms could be fitted to the Langmuir equation. Subsequently, the derived Langmuir equation parameters were combined with two kinetic models, the transport dispersive (TD) and the lumped pore diffusion (POR) models, to simulate breakthrough curves of the substances on the ion exchanger columns. In the case of the proteins, simulations based on the experimentally derived Langmuir parameters showed poor correlation with the experimental breakthrough curves. When the Langmuir parameters were instead fitted in the simulations, adequate agreement could be achieved. In the case of the TD model, the overall mass transfer parameter had to also be fitted as a function of the protein concentration to optimize the fit. In the case of the POR model, one set of transport parameters could be used to simulate the breakthrough curves independent of the mobile phase composition (buffer concentration 75 or 120 mM, NaCl concentration 0–5 %) or the protein concentration (0.001–0.3 mg/mL). As in the TD model, it was not possible to use the experimentally derived Langmuir parameters to simulate the breakthrough curves with the POR model. Instead, the Langmuir parameters had to be fitted for each individual case in order to achieve agreement. Neither the TD nor the POR model could satisfactorily simulate the behavior of the synthetic polyelectrolyte. The Langmuir equation can thus be used to provide standard transport models with an adsorption formalism to simulate breakthrough curves in ion exchange chromatography. However, the existence of a close correlation of the actually observed physico‐chemical adsorption behavior of the involved proteins could not be supported.
Chromatography Based Purification of rhGM‐CSF from Recombinant Rice Cell Culture
Authors: Hwang S. Y. , Lee E. K. , Terashima M. 
Published: November 2005

AbstractPlant cells are increasingly used as alternative host organisms for recombinant protein production requiring post‐translational modifications because they have relatively low risks of hazardous viral contamination compared to animal cells. On the other hand, the plant cell culture route has intrinsic disadvantages, including a relatively low expression titer and difficulties in the purification. We developed a simple and scalable, chromatography based process to purify rhGM‐CSF from recombinant rice cell culture. It consisted of cell removal by microfiltration, ammonium sulfate precipitation, anion exchange chromatography, and SEC‐HPLC. α‐Amylase, used as a leader sequence in the expression vector, was the major impurity protein co‐purified with rhGM‐CSF. The purification process resulted in a final purity of ca. 95 % (as verified by size exclusion chromatography) and an overall recovery yield of ca. 48 % from the culture broth (as verified by ELISA).
Simulated Moving Bed Operation for Size Exclusion Plasmid Purification
Authors: Paredes G. , Makart S. , Stadler J. , Mazzotti M. 
Published: November 2005

AbstractInterest in producing large amounts of plasmid DNA (pDNA) has increased in the last decade as a result of the advances made in gene therapy and DNA vaccines. The last stage of the manufacturing process involves a purification scheme guaranteeing a safe and stable product, considering the authorities' recommendations. This work studies the first step of the purification scheme, i.e., a group separation step based on size exclusion chromatography and using the simulated moving bed technology (SMB). The cleaning in place, crucial for the process validation, is implemented into the SMB in the so‐called CIP‐SMB configuration. Experiments were designed using the simple approach of triangle theory. The feed consisted of a clarified cleared lysate. The results indicate that total recovery of pDNA is possible and that the productivity can be tuned considering the trade‐off with purity. Detailed simulations were used to validate these results after a cleared lysate model was established.
Protein Mass Transfer Kinetics in Ion Exchange Media: Measurements and Interpretations
Authors: Carta G. , Ubiera A. R. , Pabst T. M. 
Published: November 2005

AbstractThe paper gives a summary of successful methods for measuring protein mass transfer kinetics in ion exchange matrices along with models needed to interpret experimental results. Both macroscopic methods (isocratic elution, gradient elution, batch adsorption, frontal analysis) and microscopic methods are considered. In all cases the main focus is the determination of the effective intraparticle diffusivity in order to permit a comparison of different stationary phases and provide a basis for predicting chromatographic process performance. Experimental results for representative systems are evaluated alongside the experimental and modeling aspects. Practical criteria for the selection of experimental conditions and the application of different models are discussed along with the advantages and disadvantages of the various approaches.
Optimization of SMB Technology Working as a Single Column System
Authors: Pötschacher P. 
Published: November 2005

AbstractThe scope of this work was the design, installation, testing and optimization of a pilot plant for simulated moving bed (SMB) chromatography applying the single column technology (ESMB). The working volume of the resin used as the adsorbent changes during loading and regeneration. Resin breathing leads to poor separation performance. In a single packed bed column simultaneous expansion and contraction of the resin bed equalize each other, which leads to a better separation performance. In order to reach industrial targets the SMB unit is optimized by the adaptation of several process parameters. During optimization the behavior of the system with regards to concentration profile and pressure is examined. Other feedback parameters are the purity and yield of the withdrawn liquids. A working diagram is used for the prediction and explanation of the behavior of the process. The standard triangle diagram has been adapted to the particularities of the process.
Preparative Gradient Chromatography
Authors: Seidel‐Morgenstern A. 
Published: November 2005

AbstractDuring a chromatographic separation, it is convenient to keep the essential operating parameters like temperature, pressure, mobile phase flow‐rate, and mobile phase composition constant. Though, it is well known that in contrast to this isocratic operation the intelligent modulation of certain operating parameters can improve the separation performance significantly. Such gradient approaches are widely applied in analytical (linear) chromatography to reduce the time of analysis and to enhance the selectivity. In contrast, the extent of application of these gradients is still rather limited in the field of preparative (nonlinear) chromatography. The first part of this paper is devoted to the discussion of the principal differences between linear and nonlinear and isocratic and gradient chromatography. The second part focuses on introducing a countercurrent process that allows separation in a continuous manner, efficiently exploiting a two‐step solvent composition gradient.
Industrial Scale cGMP Purification of Pharmaceutical Grade Plasmid‐DNA
Authors: Urthaler J. , Buchinger W. , Necina R. 
Published: November 2005

AbstractThe advances in gene therapy and genetic vaccination based on plasmid DNA result in an increasing demand of pharmaceutical grade plasmids produced under cGMP. A generic process consisting of a cell disintegration step followed by three different chromatography steps has been developed. Cell lysis is performed by an automated continuous reactor. The clarified lysate is further purified by hydrophobic interaction, anion exchange, size exclusion chromatography and by an ultra‐filtration step. The produced plasmid DNA was up to 98 % in the supercoiled form. The final genomic DNA content was lower than 10 μg/mg plasmid DNA, RNA was not detectable by agarose gel electrophoresis, the protein content was lower than 1 μg/mg plasmid DNA and the endotoxin content lower than 0.1 EU/mg plasmid DNA. An overall yield of 50 % and higher in the desired final buffer could be obtained. This process is scalable and does not require animal derived materials, detergents or organic solvents, meeting current standards for therapeutic applications.
Properties and Characterization of High Capacity Resins for Biochromatography
Authors: Müller E. 
Published: November 2005

AbstractAt the moment ion exchanger resins display the highest binding capacities for proteins. Polymeric surface modification methods utilize the full pore space and allow to guarantee high capacities for small as well as for large proteins. Capacity maximization is also possible by pore size optimization fitting the pore size to the molecule size without loosing a lot of dynamic binding capacity under current process conditions. Further improvements of resins can be achieved by optimizing the pore structure and pore volume, which could enhance the mass transfer and so the dynamic binding capacity.
Aspects of Modeling a Preparative Ion‐Exchange Step for Antibody Purification
Authors: Nilsson B. 
Published: November 2005

AbstractIn protein chromatography large molecules have to diffuse into the stationary phase. The molecular sizes of the proteins make the diffusion rates low or very low and the separation can be assumed to be mass transfer limited. In this study three different prepacked columns, with different bead sizes, are used for the separation of IgG and BSA to confirm or reject this assumption in an ion‐exchange application. The separations are modeled and calibrated against gradient elution data. Model calibration of reaction‐dispersive, transport‐dispersive and general rate model structures are discussed and the analysis shows that the columns are best modeled by different model structures, because different behaviors are rate‐limiting. Experiments can be described surprisingly well by reaction‐dispersive model structures, especially for BSA. Broad elution peaks for IgG indicate mass transfer limitations. Calibration of models capturing diffusive effects shows that the pore diffusion coefficients are much higher than expected, compared with the literature, indicating that there are other forces dominating the mass transport in the beads.
Shallow Bed Adsorption: Theoretical Background and Applications
Authors: Hahn R. , Tscheliessnig A. , Zöchling A. , Jungbauer A. 
Published: November 2005

AbstractThe estimation of parameters for the design of chromatography columns at extremely small scale is required when the amount of feed stock or gel material is limited. The method of shallow bed adsorption, also known as zero length column or differential contactor allows the estimation of uptake kinetics and equilibria, at a scale of less than 100 μL bed volume. The shallow bed is an infinite bath, which assumes that the liquid phase concentration does not change during the process of adsorption. This is achieved by keeping the volume of the stationary phase negligibly small so that the bound material does not influence the liquid phase concentration. Several examples are given to demonstrate the usefulness of this method and a protocol is suggested as to how it can be implemented in process development.
Preferred 3D‐Structure of Peptides Rich in a Severely Conformationally Restricted Cyclopropane Analogue of Phenylalanine
Authors: Crisma Marco , De Borggraeve Wim M. , Peggion Cristina , Formaggio Fernando , Royo Soledad , Jiménez Ana I. , Cativiela Carlos , Toniolo Claudio 
Published: November 2005

AbstractTerminally blocked, homo‐peptide amides of (R,R)‐1‐amino‐2,3‐diphenylcyclopropane‐1‐carboxylic acid (c3diPhe), a chiral member of the family of Cα‐tetrasubstituted α‐amino acids, from the dimer to the tetramer, and diastereomeric co‐oligopeptides of (R,R)‐ or (S,S)‐c3diPhe with (S)‐alanine residues to the trimer level were prepared in solution and fully characterized. The synthetic effort was extended to terminally protected co‐oligopeptide esters to the hexamer, where c3diPhe residues are combined with achiral α‐aminoisobutyric acid residues. The preferred conformations of the peptides were assessed in solution by FT‐IR absorption, NMR, and CD techniques, and for seven oligomers in the crystal state (by X‐ray diffraction) as well. This study clearly indicates that c3diPhe, a sterically demanding cyclopropane analogue of phenylalanine, tends to fold peptides into β‐turn and 310‐helix conformations. However, when c3diPhe is in combination with other chiral residues, the conformation preferred by the resulting peptides is also dictated by the chiral sequence of the amino acid building blocks. The (S,S)‐enantiomer of this α‐amino acid, unusually lacking asymmetry in the main chain, strongly favors the left‐handedness of the turn/helical peptides formed.
Controlling Stereochemical Outcomes of Asymmetric Processes by Catalyst Remote Molecular Functionalizations: Chiral Diamino‐oligothiophenes (DATs) as Ligands in Asymmetric Catalysis
Authors: Albano Vincenzo Giulio , Bandini Marco , Barbarella Giovanna , Melucci Manuela , Monari Magda , Piccinelli Fabio , Tommasi Simona , Umani‐Ronchi Achille 
Published: November 2005

AbstractThe synthesis, characterization, and structure‐guided application of a new class of highly versatile chiral C2‐symmetric diamine‐oligothiophene ligands in Pd‐catalyzed asymmetric transformations are presented. Experimental investigations of the intimate role of pendant π‐conjugate oligothiophenes in determining the catalytic activity of the corresponding chiral Pd complexes are described. Their unusual behavior opens up new routes toward the logical design of finely tuned organometallic catalysts by remote structural functionalizations.
Development of a Ligand Knowledge Base, Part 1: Computational Descriptors for Phosphorus Donor Ligands
Authors: Fey Natalie , Tsipis Athanassios C. , Harris Stephanie E. , Harvey Jeremy N. , Orpen A. Guy , Mansson Ralph A. 
Published: November 2005

AbstractA prototype collection of knowledge on ligands in metal complexes, termed a ligand knowledge base (LKB), has been developed. This contribution describes the design of DFT‐calculated descriptors for monodentate phosphorus(III) donor ligands in a range of representative complexes. Using the resulting data, a ligand space is mapped and predictive models are derived for metal complexes. Important characteristics, including chemical, computational and statistical robustness for the generation and exploitation of such an LKB are described. Chemical robustness ensures transferability of the descriptors, as well as comprehensive sampling of ligand space. To make the calculations amenable to automation in an e‐science setting, a reliable, well‐defined computational approach has been sought from which the descriptors can be readily extracted. The LKB has been explored with multivariate statistical methods. Principal component analysis (PCA) is used for the mapping of chemical space, projecting multiple descriptors into scatter plots which illustrate the clustering of chemically similar ligands. Interpretation of the resulting principal components in terms of established steric and electronic properties and the importance of its statistical robustness to variations in the ligand set are discussed. Multiple linear regression (MLR) models have been derived, demonstrating the versatility of the descriptors for modeling varied experimentally determined parameters (bond lengths, reaction enthalpies and bond‐stretching frequencies). The importance of re‐sampling methods for testing the robustness of predictions is highlighted. A strategy for the construction of a robust LKB suitable for the modeling of ligand and complex behavior is outlined based on these observations.
The Indium Subnitrides M6In4(InxLiy)N3‐z (M: Sr and Ba).
Authors: Bailey Mark S. , Shen Daniel Y. , McGuire Michael A. , Fredrickson Daniel C. , Toby Brian H. , DiSalvo Francis J. , Yamane Hisanori , Sasaki Shinya , Shimada Masahiko 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis and Characterization of [PtIn6](GeO4)2O and Its Solid Solution [PtIn6] (GaO4)2‐x(GeO4)xOx/2 (0 ≤ x ≤ 2): Gradual Color Change of the Solid Solution from Black (x = 0) to Yellow (x = 2) as a Consequence of Quantum Dot Effect.
Authors: Koehler Juergen , Friedrich Holger , Whangbo Myung‐Hwan , Villesuzanne Antoine 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Aminomethylene Ketones and Enamines in Heterocyclic Synthesis: Synthesis of Functionally Substituted Pyridine, Pyrazole, Fused Pyrimidine and Fused [1,5]Diazocine Derivatives
Authors: Hassanien Abu Zeid A. , Mohamed Mona H. , Gohzlan Said A. S. 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Mn(III)‐Based C—C Bond Formation: Regioselective α′‐Allylation of Various α,β‐Unsaturated, α‐ and β‐Alkoxy α,β‐Unsaturated Ketones.
Authors: Tanyeli Cihangir , Oezdemirhan Devrim 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
An Efficient Dehydrohalogenation Method for the Synthesis of α,β,β‐Trifluorostyrenes, α‐Chloro‐β,β‐difluorostyrenes and E‐1‐Arylperfluoroalkenes.
Authors: Anilkumar R. , Burton Donald J. 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Asymmetric Synthesis of Cyclopropanes from Lithiated Aryloxiranes and α,β‐Unsaturated Fischer Carbene Complexes.
Authors: Capriati Vito , Florio Saverio , Luisi Renzo , Perna Filippo Maria , Barluenga Jose 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Modular Synthesis of Chiral Homo‐ and Heterotrisoxazolines. Improving the Enantioselectivity in the Asymmetric Michael Addition of Indole to Benzylidene Malonate.
Authors: Ye Meng‐Chun , Li Bin , Zhou Jian , Sun Xiu‐Li , Tang Yong 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis and the Reactions of Trifluoromethylated 1,2,3‐Triketones 2‐(Het)arylhydrazones and 4,7‐Dihydroazolo[5,1‐c]triazines.
Authors: Khudina O. G. , Shchegol'kov E. V. , Burgart Ya. V. , Kodess M. I. , Kazheva O. N. , Chekhlov A. N. , Shilov G. V. , Dyachenko O. A. , Saloutin V. I. , Chupakhin O. N. 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Efficient and Eco‐Friendly Process for the Synthesis of N‐Substituted 4‐Methylene‐2‐oxazolidinones in Ionic Liquids.
Authors: Zhang Qinghua , Shi Feng , Gu Yanlong , Yang Jing , Deng Youquan 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Champanones, Yellow Pigments from the Seeds of Champa (Campomanesia lineatifolia).
Authors: Bonilla Adriana , Duque Carmenza , Garzon Cristina , Takaishi Yoshihisa , Yamaguchi Kazutaka , Hara Noriyuki , Fujimoto Yoshinori 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Asymmetric Hydrogenation of N‐Sulfonylated‐α‐dehydroamino Acids: Toward the Synthesis of an Anthrax Lethal Factor Inhibitor.
Authors: Shultz C. Scott , Dreher Spencer D. , Ikemoto Norihiro , Williams J. Michael , Grabowski Edward J. J. , Krska Shane W. , Sun Yongkui , Dormer Peter G. , DiMichele Lisa 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Unusual Dimethyl Ketal from Cycloadduct of 4,6‐O‐Benzylidene‐D‐allal and Dichloroketene.
Authors: Chun Keun Ho , Yoon Taemoon , Shin Jeoung E Nam , Jo Choonsil , Jo Yun Ju , Yun Hoseop , Oh Jonghoon 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Isolation and Synthesis of a Novel β‐Carboline Guanidine Derivative Tiruchanduramine from the Indian Ascidian Synoicum macroglossum
Authors: Ravinder K. , Reddy A. Vijender , Krishnaiah P. , Ramesh P. , Ramakrishna S. , Laatsch H. , Venkateswarlu Y. 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
An Efficient Two‐Step Synthesis of Jensenone Isolated from Eucalyptus jensenii. Synthesis of Analogues and Evaluation as Antioxidants.
Authors: Bharate Sandip B. , Chauthe Siddheshwar K. , Bhutani Kamlesh K. , Singh Inder P. 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of Multi‐Walled and Bamboo‐Like Well‐Crystalline CNx Nanotubes with Controllable Nitrogen Concentration (x = 0.05‐1.02).
Authors: Xiong Yujie , Li Zhengquan , Guo Qixun , Xie Yi 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Conical Cavitands as Second Coordination Spheres and Protecting Environments. Toward Metal‐Centered, Intracavity Reactions
Authors: Armspach D. , Bagatin I. , Engeldinger E. , Jeunesse C. , Harrowfield J. , Lejeune M. , Matt D. 
Published: November 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Asymmetric ring opening of terminal epoxides via kinetic resolution catalyzed by new bimetallic chiral (salen)Co complexes
Authors: Thakur Santosh Singh , Li Wen‐Ji , Shin Chang‐Kyo , Kim Geon‐Joong 
Published: November 2005

AbstractThe highly enantioselective hydrolytic kinetic resolution (HKR) of racemic terminal epoxides by new bimetallic chiral (salen)Co provides a operationally very simple protocol for the synthesis of enantiomerically enriched terminal epoxides (>99% ee) and diols. Optically pure chlorohydrins have been synthesized in one step by ring‐opening reactions of terminal epoxides with HCl using kinetic resolution. © 2005 Wiley‐Liss, Inc. Chirality
Secondary Synthesis of Two Cobalt Complexes by the Use of 5‐Sulfosalicylate and 1,10‐Phenanthroline and Their Crystal Structures
Authors: Fan Sai‐Rong , Zhu Long‐Guan 
Published: November 2005

AbstractCobalt(II) nitrate reacted with 1,10‐phenanthroline (phen) and 5‐sulfosalicylic acid (H3ssal) to yield the cobalt(II) complex [Co(phen)2(H2O)2](Hssal)·4H2O (1) and the reaction of 1 with copper acetate led to a novel complex [Co(phen)(H2O)4][Cu2(ssal)2(phen)2]·5H2O (2). These two complexes were cation‐anion species and the cationic motif [Co(phen)2(H2O)2]2+of 1 could be converted to [Co(phen)(H2O)4]2+ in the formation process of new anion [Cu2(phen)2(ssal)2]2− of 2. In both complexes abundant hydrogen bonds construct different supramolecular architectures, thus the conversion reaction can provide a new path to create novel supramolecular network.
Organic Nanotubes Prepared from Chiral Molecules by the Template Method
Authors: Zhao Li‐Yun , Yang Wen‐Sheng , Yang Zi‐Wen , Yao Jian‐Nian 
Published: November 2005

AbstractOrganic nanotubes from two kinds of chiral molecules, R‐di‐2‐naphthylprolinol (DNP) with an asymmetric carbon atom and R‐(+)‐1,1'‐bi‐2‐naphthol dimethyl ether (BNDE) with the conformational asymmetry, were prepared by the immersing technique using porous alumina membranes as the template. It was found that the nanotubes from DNP with an asymmetric carbon atom presented the same chirality as the solution with slight red shift of the CD signals upon the formation of the nanotubes, while no well‐defined chirality could be identified for the nanotubes from BNDE with the conformational asymmetry.