bluuebunny/crossref_metadata_2025 huggingface dataset:
Tetrathionate Disproportionation by Thiomonas intermedia K12
Authors: Wentzien S. , Sand W.
Published: February 2004

Thiomonas intermedia K12, a moderately acidophilic bacterium, which oxidises sulphur compounds, – exhibited the capability to use tetrathionate under oxic and anoxic conditions. Whereas under oxic conditions, the reduced sulphur tetrathionate compound was oxidised, under anoxic conditions, the organism disproportionated the compound. In both cases, trithionate and sulphate were produced but in different amounts. The results of the tetrathionate degradation experiments under oxic conditions pointed towards a cyclic degradation process with a transient formation of trithionate and sulphate as the final products, similar to the mechanism described for acidophilic sulphur compound oxidising bacteria. The results of the tetrathionate degradation experiments under anoxic conditions hinted to a partial reduction of tetrathionate to thiosulphate and a fractional oxidation to trithionate and sulphate. 4 M tetrathionate were converted to 6 M thiosulphate, 1 M trithionate, 1 M sulphate, and 8 M protons. The ΔG0' of this reaction was found to be –16.1 kJ per mol tetrathionate degraded. Additionally, Thiomonas intermedia K12 grew under anoxic conditions with tetrathionate as the sole energy source. The cell numbers increased from 105 as the start value to 107/mL at the end. Organic compounds, excluding traces of yeast extract, did not enhance growth. Therefore, it is proposed that tetrathionate disproportionation is a novel lithotrophic metabolism, which allowed Thiomonas intermedia K12 to survive changing conditions of oxygen supply in sulphur‐compound‐rich environments and even to grow during this reaction. The extensive sulphur compound analysis was carried out by ion‐pair chromatography.
Capacity of Salvinia minima Baker to Tolerate and Accumulate As and Pb
Authors: Hoffmann T. , Kutter C. , Santamaría J.
Published: February 2004

The use of Salvinia minima Baker for the removal of lead (Pb) and arsenic (As) from aqueous solutions was investigated. In a first approach, the effect of different concentrations of AsO43– and Pb(II) on the growth and accumulation of these metals was studied. The plants tolerated concentrations of 20–40 μM Pb(II) and 200 μM of AsO43–. Toxic effects occurred when 20 μM of Pb(II) and 100 μM AsO43– were used. These effects included growth inhibition (decreased yield of biomass and frond area) as well as an altered frond (leaf‐like structure in ferns) appearance and tissue consistence. S. minima showed a high uptake of Pb (34 mg/g dry weight) compared to As (0.5 mg/g dry weight). The uptake of As was inhibited by phosphate. Additional kinetic studies revealed a two‐stage accumulation of both elements: a rapid first phase within the first 6–12 hours and a slow second phase up to the end of the 96‐hour experiment.
Anaerobic Hydrogen Production from Sucrose Using an Acid‐Enriched Sewage Sludge Microflora
Authors: Lin C.Y. , Chou C.H.
Published: February 2004

A novel and high‐rate anaerobic sequencing bath reactor (ASBR) process was used to evaluate the hydrogen productivity of an acid‐enriched sewage sludge microflora at a temperature of 35 °C. In this ASBR process a 4 h cycle, including feed, reaction, settle, and decant steps, was repeatedly performed in a 5 L reactor. The sucrose substrate concentration was 20 g COD/L; the hydraulic retention time (HRT) was maintained at 12–120 h at the initial period and thereafter at 4–12 h. The reaction/settle period ratio, which is the most important parameter for ASBR operation was 1.7. The experimental results indicated that the hydrogenic activity of the sludge microflora was HRT‐dependent and that proper pH control was necessary for a stable operation of the bioreactor. The peak hydrogenic activity value was attained at an HRT of 8 h and an organic loading rate of 80 kg COD/m3 × day. Each mole of sucrose in the reactor produced 2.8 mol of hydrogen and each gram of biomass produced 39 mmol of hydrogen per day. An overly‐short HRT might deteriorate the hydrogen productivity. The concentration ratios of butyric acid to’acetic acid, as well as volatile fatty acid and soluble microbial products to alkalinity can be used as monitoring indicators for the hydrogenic bioreactor.
A Novel Olive Oil Degrading Thermoactinomyces Species with a High Extremely Thermostable Lipase Activity
Authors: Al‐Khudary R. , Hashwa F. , Mroueh M.
Published: February 2004

A filamentous, Gram‐positive, spore forming aerobic bacterium was isolated from olive oil contaminated soil (Al Koura, Lebanon) on rhodamine agar plates at 60 °C. The isolate, HRK‐1 produced large quantities of an extracellular thermostable lipase which degrades olive oil. It was primarily classified as a Thermoactinomyces sp. due to the filamentous structure of its cells that bear one spore each on an un‐branched sporophore, the resistance of its spores to boiling, utilisation of sucrose as a carbon source and production of dark pigments. The isolate grew optimally at a temperature of 60 °C, a pH of 7.3 and an orbital shaking of 250 rpm. It showed an efficient olive oil degrading ability. No traces of triolein were detected after a 36‐h cultivation. A concentration of 10 % [v/v] olive oil did not inhibit its growth. Lipase production was constitutive, and did not depend on the presence of olive oil. The optimum concentration of olive oil for lipase activity was 1 % [v/v], and the activity was not enhanced at higher concentrations, but on the contrary, a decrease in enzyme activity was recorded. The lipase of HRK‐1 was preliminarily characterised in the crude cell‐free supernatant with a specific activity of 0.14 U/mg. It has an optimum activity at 60 °C and a pH of 8.0. This lipolytic enzyme showed resistance to boiling and to a wide range of metallic ions and inhibitors. The formation of this heat‐stable lipase started in the early exponential growth phase, while a maximum extracellular enzyme activity was detected at the end of the decline phase, when most of the cells appeared as spherical spores. The exceptionally high activity of lipase (2.37 U/ml) produced by HRK‐1 measured in the cell free supernatant clearly indicated the commercial importance of this isolate, especially after it showed great stability at elevated temperatures.
New Process to Minimize Effluent Water in the Production of DNT
Authors: Winterbauer H.
Published: February 2004

Until recently, freshwater had to be used for “neutral washing” in the DNT production. Using the new process outlined in this communication, it is now possible to recycle process condensate from the concentration of sulfuric acid. No additional freshwater is needed and the effluent water stream to be treated is also correspondingly reduced. MNT and DNT are recovered and recycled to the production process. Losses are minimized.
Modular Structure of Biochips Based on Microstructured Deposition of Functional Nanoparticles
Authors: Weber A. , Knecht S. , Brunner H. , Tovar G.E.M.
Published: February 2004

This paper presents the microstructured deposition of nanoparticles, which are chemically modified to be conjugated to biomolecules or dyes. In our approach, we separated the technical steps “surface chemistry” and “microstructuring” into two fully independent processes. This was realized by firstly synthesizing specific nanoparticles with tailor‐made surfaces. Thus, the surface chemistry was customized to the demands of most different kinds of specific proteins. Then, microstructured monolayer arrays of these nanoparticles were generated by photolithography, microcontact printing or spotting with a microarrayer. The overall system resulted in a nanoparticle‐based microarray for the selective binding of protein ligands providing both wide flexibility and high specificity.
In vitro Degradation of 2,4,6‐Trinitrotoluene Using Plant Tissue Cultures of Solanum aviculare and Rheum palmatum
Authors: Nepovím A. , Hubálek M. , Podlipná R. , Zeman S. , Vanek T.
Published: February 2004

The degradation of TNT was tested in suspension cultures (Rheum palmatum and Solanum aviculare) and was followed by the identification of degradation products and the determination of the phytotoxicity of TNT to both cultures. The concentration of TNT inhibited the growth of cell cultures by 50 %, i.e., 37.8 mg/ and 38.1 mg/L for Rheum palmatum and Solanum aviculare, respectively. The TNT uptake was studied by determining the concentration of TNT and its degradation products, such as aminodinitrotoluenes and diaminonitrotoluenes, in the cultivation medium as well as in plant cells. The kinetics of the degradation showed that TNT was mostly taken up within 10 hours and 6 hours for S. aviculare and R. palmatum, respectively. Aminodinitrotoluenes were preferentially produced by cultures of S. aviculare, whereas diaminonitrotoluenes and aminodinitrotoluenes were revealed in cultures of R. palmatum. The final concentrations of identified degradation products did not stoichiometrically correspond to the decreased concentration of TNT in the medium. The different concentrations of degradation products in each culture were an indication that the metabolism of TNT is controlled by different enzymatic systems. Therefore, it was concluded that studying different species for TNT degradation is necessary for the search of most suitable candidates for TNT phytoremediation.
Comparison of the Heavy Metal Biosorption Capacity of Active, Heat‐Inactivated and NaOH‐Treated Phanerochaete chrysosporium Biosorbents
Authors: Gürişik E. , Arica M.Y. , Bektaş S. , Genç Ö.
Published: February 2004

Three different kinds of Phanerochaete chrysosporium (NaOH‐treated, heat‐inactivated and active) biosorbent were used for the removal of Cd(II) and Hg(II) ions from aquatic systems. The biosorption of Cd(II) and Hg(II) ions on three different forms of Phanerochaete chrysosporium was studied in aqueous solutions in the concentration range of 50–700 mg/L. Maximum biosorption capacities of NaOH‐treated, heat‐inactivated and active Phanerochaete chrysosporium biomass were found to be 148.37 mg/g, 78.68 mg/g and 68.56 mg/g for Cd(II) as well as 224.67 mg/g, 122.37 mg/g and 88.26 mg/g for Hg(II), respectively. For Cd(II) and Hg(II) ions, the order of affinity of the biosorbents was arranged as NaOH‐treated > heat‐inactivated > active. The order of the amount of metal ions adsorbed was established as Hg(II) > Cd(II) on a weight basis, and as Cd(II) > Hg(II) on a molar basis. Biosorption equilibriums were established in about 60 min. The effect of the pH was also investigated, and maximum rates of biosorption of metal ions on the three different forms of Phanerochaete chrysosporium were observed at pH 6.0. The reusability experiments and synthetic wastewater studies were carried out with the most effective form, i.e., the NaOH‐treated Phanerochaete chrysosporium biomass. It was observed that the biosorbent could be regenerated using 10 mM HCl solution, with a recovery of up to 98%, and it could be reused in five biosorption‐desorption cycles without any considerable loss in biosorption capacity. The alkali‐treated Phanerochaete chrysosporium removed 73% of Cd(II) and 81% of Hg(II) ions from synthetic wastewater.
On frequency domain equalization for MC‐CDMA in Nakagami fading channels
Authors: Abdel‐Hafez Mohammed , Li Zexian , Latva‐aho Matti
Published: February 2004

In this letter, we evaluate the performance of multicarrier code division multiple access (MC‐CDMA) in terms of average bit error probability (BEP) in Nakagami fading channels. The results are applicable to MC‐CDMA systems employing coherent demodulation with maximal‐ratio combining (MRC) or equal gain combining (EGC) reception. The effects of fading parameters and number of users are presented. The accuracy of the proposed analysis is demonstrated by computer simulations. The BEP performance of the EGC receiver in the uplink is highly influenced by the fading parameter compared with that of the MRC receiver. The EGC receiver outperforms the MRC receiver in the downlink, but the MRC receiver gives almost the same performance as the EGC in the uplink. Copyright © 2004 AEI
Effects of user distribution on the delay performance of downlink packet access in 3GPP WCDMA networks
Authors: Fu Hua , Thompson John S.
Published: February 2004

This paper is concerned with the effects of user distribution on the delay performance of packet access in wideband code division multiple access (WCDMA) downlink networks. The characteristics of a packet‐switched data traffic model which mimics internet web browsing is presented. The cellular system model is based on the release 4 configuration of the third Generation Partnership Project (3GPP) technical specification. The investigation incorporates traffic channel power allocation, fast power control, data traffic characteristics, data activity factor, different user distributions, hot‐spot scenarios, base station sectorization schemes and antenna beam patterns. Two types of system level Monte‐Carlo simulations are proposed and a performance comparison is given. The results include the overall delay performance and their sensitivities to a diverse set of parameters. Copyright © 2004 AEI
Impact of local coding efficiency on the modelling of flows derived from VBR MPEG2 video coding
Authors: Corlay Patrick , Gazalet Marc Georges , Coudoux François‐Xavier , Grimbert Laurent
Published: February 2004

This Letter proposes a cell generation model based on a MMPP(2) process which aims to simulate the unsmoothed data output from a variable bit rate (VBR) MPEG‐2 video encoder. By taking into account the coding efficiency in some image zones, we have improved the modelling. This coding efficiency is directly related to the properties of the compression methods used and may lead to a periodic phenomena given the inter‐arrival times between data. The developed model integrates this periodicity in order to refine the modelling. Experimental simulations of VBR MPEG video transmission over ATM were performed to validate this approach. The results expressed in terms of the inter‐arrival time characteristics show the improvement brought by accounting for local coding efficiency. Copyright © 2004 AEI
Focal astrocyte loss is followed by microvascular damage, with subsequent repair of the blood‐brain barrier in the apparent absence of direct astrocytic contact
Authors: Willis Colin L. , Nolan Christopher C. , Reith Sharon N. , Lister Timothy , Prior Malcolm J.W. , Guerin Christopher J. , Mavroudis George , Ray David E.
Published: February 2004

Blood‐brain barrier (BBB) breakdown is a feature of cerebral ischaemia, multiple sclerosis, and other neurodegenerative diseases, yet the relationship between astrocytes and the BBB integrity remains unclear. We present a simple in vivo model in which primary astrocyte loss is followed by microvascular damage, using the metabolic toxin 3‐chloropropanediol (S‐α‐chlorohydrin). This model is uncomplicated by trauma, ischaemia, or primary immune involvement, permitting the study of the role of astrocytes in vascular endothelium integrity, maintenance of the BBB, and neuronal function. Male Fisher F344 rats given 3‐chloropropanediol show astrocytic damage and death at 4–24 h in symmetrical brainstem and midbrain nuclear lesions, while neurons show morphological changes at 24–48 h. Fluorescent 10 kDa dextran tracers show the BBB leaking from 24 h, progressing to petechial haemorrhage after 48–72 h, with apparent repair after 6 days. BBB breakdown, but not the earlier astrocytic death, is accompanied by a delayed increase in blood flow in the inferior colliculus. An ED1 inflammatory response develops well after astrocyte loss, suggesting that inflammation may not be a factor in starting BBB breakdown. This model demonstrates that the BBB can self‐repair despite the apparent absence of direct astrocytic‐endothelial contact. The temporal separation of pathological events allows pharmacological intervention, and the mild reversible ataxia permits long‐term survival studies of repair mechanisms. © 2003 Wiley‐Liss, Inc.
Regulation of MHC class II expression in glioma cells by class II transactivator (CIITA)
Authors: Takamura Yukio , Ikeda Hideyuki , Kanaseki Takayuki , Toyota Minoru , Tokino Takashi , Imai Kohzoh , Houkin Kiyohiro , Sato Noriyuki
Published: February 2004

We first classified 12 malignant glioma cell lines into three different groups (types 1–3) with respect to major histocompatibility complex (MHC) class II expression and analyzed each group based on the different expression status of the class II transactivator (CIITA) gene. Glioma type 1 (2 of 12) showed constitutive expression of all class II molecules that might be mediated by activation of B cell‐specific CIITA promoter III. Glioma type 2 represented the major phenotype (66.7 %) of malignant glioma cell lines, and MHC class II expression was induced by interferon‐γ (IFN‐γ) in this phenotype. Analysis of glioma tissue samples revealed that CIITA promoter IV was detected in 9 of 11 patients (81.8%); however, promoter III was only in two (18.2%). Moreover, cultured glioma cells obtained from a fresh tumor sample upregulated expression of CIITA and class II molecules in the presence of IFN‐γ, strongly suggesting that glioma type 2 might be predominant in glioma tissues. Glioma type 3 (2 of 12) showed CIITA transcripts but loss of MHC class II expression even in the presence of IFN‐γ. In addition, we determined that the constitutive MHC class II expression in the glioma cell lines (type 1) was the result of transcriptional activation of the CIITA gene. This phenomenon was mediated by global histone acetylation over 6 kb upstream from the transcriptional start site of CIITA promoter III. Moreover, stable transfection of CIITA promoter IV as well as promoter III into MHC class II inducible cell lines restored the constitutive expression of all class II molecules. These studies lay the foundation to understand the molecular basis for the expression of class II molecules in gliomas. © 2003 Wiley‐Liss, Inc.
Different uptake of cobalamin (vitamin B12) by astrocytes and oligodendrocytes isolated from rat spinal cord
Authors: Buccellato Francesca R. , Foi Laura , Veber Daniela , Pravettoni Giulio , Scalabrino Giuseppe
Published: February 2004

In the present study, we hypothesized that cobalamin (Cbl) deficiency might affect astrocytes and oligodendrocytes of rat spinal cord (SC) differently. Radiolabeled Cbl ([Cyano‐14C]cyano‐Cbl) was used to investigate whether the in vitro uptake of Cbl is different in primary cultures of oligodendrocytes and astrocytes. In culture medium supplemented with serum that naturally contains Cbl, the time course of labeled Cbl uptake by neonatal oligodendrocytes had two peaks, at 8 h and 24 h. No uptake was observed when the same cells were cultured in a serum‐free medium and consequently in the absence of Cbl. Oligodendrocytes isolated from adult rat SC showed no uptake under any of the tested conditions. Astrocytes isolated from adult Cbl‐deficient and newborn rat SC, both cultured in a medium supplemented with serum, showed peak Cbl uptake at 8 h and 12 h, respectively, whereas those isolated from the SC of an adult normal rat cultured under the same conditions showed no uptake throughout the experimental period. Astrocytes isolated from normal, Cbl‐deficient adult rats and newborns cultured in a serum‐free medium not containing Cbl, showed a similar trend of Cbl uptake with a peak at 24 h. Oligodendrocytes isolated from Cbl‐deficient rats showed no uptake when cultured in medium with or without serum. This study provides evidence for a difference in the uptake of labeled Cbl between rat SC astrocytes and oligodendrocytes in relation to (1) age of the donor SC, (2) Cbl status of the donor SC, and (3) Cbl deficiency in the incubation medium that facilitates Cbl uptake in neonatal and adult astrocytes. © 2003 Wiley‐Liss, Inc.
Ink‐jet Printing Polymers and Polymer Libraries Using Micropipettes
Authors: de Gans Berend‐Jan , Kazancioglu Emine , Meyer Wilhelm , Schubert Ulrich S.
Published: February 2004

Summary: A study is presented on ink‐jet printing polymers, aiming at library generation for combinatorial material science applications, using (optimized) micropipettes. Solvents were successfully ink‐jet printed, up to 160 mPa s viscosity. Printability of polymer solutions decreases strongly with $\overline M _{\rm w}$ and polymer concentration, due to elastic stresses originating from elongational flow in the pipette nozzle. The feasibility of ink‐jet printing to generate arrays of polymer dots and films was demonstrated.

An array of square films is shown that was created by printing a solution containing polydisperse polystyrene in acetophenone and 0.1% disperse red 1 to improve the contrast.

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An array of square films is shown that was created by printing a solution containing polydisperse polystyrene in acetophenone and 0.1% disperse red 1 to improve the contrast.
Linear Combinatorial Synthesis with Fourier Transform Library Analysis
Authors: Schwabacher Alan W. , Johnson Christopher W. , Geissinger Peter
Published: February 2004

Feature Article:Combinatorial synthesis procedures that fit a restrictively defined “fully parallel” criterion tend to be extremely efficient methods. We describe how linear library organization allows such synthesis, without loss of synthetic history information, with an example of a peptide library. Fluorescence measurements of several types are used to measure activities. A novel Fourier Transform approach to library data analysis allows robust evaluation of trends. The use of the cladding of optical fibers as linear supports for combinatorial libraries significantly extends the potential applications of the technique, allowing for spatially resolved optical evaluation of library activity using laser pulses propagating through the fiber core. Moreover, by using different fiber cladding materials, the range of chemistries amenable to one‐dimensional combinatorial synthesis is significantly increased. It is noteworthy that the procedure is particularly applicable to the fabrication and evaluation of real‐time sensor arrays.

Schematic representation of a fully parallel synthesis on a linear solid support. The result is a sequence of regions on the thread, each bearing a library member.

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Schematic representation of a fully parallel synthesis on a linear solid support. The result is a sequence of regions on the thread, each bearing a library member.
High‐Throughput Experimentation: A Powerful Enabling Technology for the Chemicals and Materials Industry
Authors: Dar Yadunandan L.
Published: February 2004

Summary: High‐throughput experimentation (HTE) and combinatorial techniques have become an active area of interest for the materials and chemicals industry. These techniques could lead to faster, safer, and more efficient processes in virtually all industrial areas. This review briefly describes related aspects of the history of HTE and combinatorial methods in the materials and chemicals industry. It further describes the recent interest by the industry in this area in light of filed and granted patent applications, which represent the efforts of various industrial groups. Many aspects of hte, including material synthesis, screening, informatics, and application testing, have been addressed. A survey of these efforts suggests that such methods are recognized as a powerful enabling technology by industry and are potentially game changing. An effort has been made to keep the discussion focused on materials and techniques relevant to chemicals and materials technology, with an emphasis on polymer and synthetic organic chemistry and the analysis of related products. In‐line with this effort, it has been attempted to exclude aspects mostly relevant to biological, genetic, and pharmaceutical technologies.

High level of interest from high‐throughput experimentation focused companies, as well as chemical companies in general, in this area of research and development.

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High level of interest from high‐throughput experimentation focused companies, as well as chemical companies in general, in this area of research and development.
Evaluation of Process Degradation of Polymer Formulations Utilizing High‐Throughput Preparation and Analysis Methods
Authors: Wroczynski Ronald J. , Rubinsztajn Malgorzata , Potyrailo Radislav A.
Published: February 2004

Summary: Polymers exhibit complex degradation mechanisms during their processing and end use. High‐throughput development of new polymer formulations requires new methods for material preparation and measurement of properties. We explore various approaches to increase the throughput and decrease the sample size for evaluating the relative effectiveness of process stabilizers for poly(propylene). Our several measurement methods for rank ordering stabilizer effectiveness are attractive for rapid identification of high performance stabilizers.

Combinatorial polymer microextrusion system.

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Combinatorial polymer microextrusion system.
Rapid Screening of New Polymer‐Supported Palladium (II) Bis(3,4,5,6‐tetrahydropyrimidin‐2‐ylidenes)
Authors: Mayr Monika , Buchmeiser Michael R.
Published: February 2004

Summary: The synthesis of two 1,3‐diaryl‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidene‐based N‐heterocyclic carbene‐ (NHC) derived palladium complexes, Pd(5‐hydroxy‐1,3‐bis‐(2,4,6‐trimethylphenyl)‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidene) (Ag2Br2Cl4) (10) and Pd(5‐(bicyclo[2.2.1]hept‐5‐ene‐2‐carbonyloxy)‐1,3‐bis‐(2,4,6‐trimethylphenyl)‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidene) (Ag2Br2Cl4) (11) is described. 10 was supported on a PS‐DVB and a Wang resin, respectively, to yield catalysts 12 and 13, while 11 was used for the synthesis of a ring‐opening metathesis precipitation polymerization‐derived support 14. All supports were tested for their activity in Heck‐type reactions using a combinatorial approach.

Structure of polymer supported Pd‐catalysts.

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Structure of polymer supported Pd‐catalysts.
Combinatorial Development of Pressure‐Sensitive Adhesives
Authors: Grunlan Jaime C. , Holguin Daniel L. , Chuang Hsiao‐Ken , Perez Isidro , Chavira Aaron , Quilatan Ryan , Akhave Jay , Mehrabi Ali R.
Published: February 2004

Summary: Combinatorial libraries of pressure‐sensitive adhesives were prepared and characterized using a spherical probe tester. Force‐displacement profiles generated for each adhesive provided information related to tack, peel, and shear behavior. These data were used to find the best adhesive, which was then used to generate a combinatorial library of varying thickness. These data demonstrate the utility of high‐throughput screening in pressure‐sensitive‐adhesive development.

Adhesive daughter plate arranged in 48‐spot array.

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Adhesive daughter plate arranged in 48‐spot array.
Mapping Surface Chemistry and Molecular Orientation with Combinatorial Near‐Edge X‐Ray Absorption Fine Structure Spectroscopy
Authors: Fischer Daniel A. , Efimenko Kirill , Bhat Rajendra R. , Sambasivan Sharadha , Genzer Jan
Published: February 2004

Summary: Mapping the bond chemistry and molecular orientation of self‐assembled monolayer gradients on flat surfaces and reaction intermediates in catalyst arrays is made possible using combinatorial near‐edge X‐ray absorption fine structure (NEXAFS) spectroscopy. These spatially resolved NEXAFS maps have been made by utilizing synchrotron‐based NEXAFS spectroscopy in conjunction with a computer controlled precision sample manipulator. The NEXAFS maps reveal bond concentration, rehybridization, and orientation of the surface‐bound molecules with sub‐millimeter planar spatial resolution and sub‐monolayer molecular sensitivity. The wide applicability of the combinatorial NEXAFS method is illustrated by mapping: (1) the concentration and molecular orientation of semifluorinated molecules in molecular gradients; (2) the concentration of amino groups in molecular gradients used for nanoparticle templating, and (3) the rehybridization of propylene intermediates on zeolite catalyst arrays used for measuring solid‐state acidity and catalyst activity.

The principle of “combinatorial” NEXAFS. The molecular gradient is indicated pictorially by the shading on the specimen.

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The principle of “combinatorial” NEXAFS. The molecular gradient is indicated pictorially by the shading on the specimen.
Parallel Synthesis and Testing of Catalysts for the Polymerization of Ethylene
Authors: Kolb Peter , Demuth Dirk , Newsam John M. , Smith Michael A. , Sundermann Andreas , Schunk Stephan Andreas , Bettonville Serge , Breulet Jacques , Francois Philippe
Published: February 2004

Summary: High throughput methodologies were applied for the synthesis and testing of late transition metal complexes of Fe with bidentate diazabutadiene or tridentate diiminopyridine ligands in the polymerization of ethylene. Fe DIP complexes with ligands derived from amines with two or three annealed aromatic rings were found to be highly active catalysts when activated with methylaluminoxane. This finding can be rationalized based on models previously developed.

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Combinatorial Electrochemical Synthesis and Screening of Mesoporous ZnO for Photocatalysis
Authors: Jaramillo Thomas F. , Baeck Sung‐Hyeon , Kleiman‐Shwarsctein Alan , McFarland Eric W.
Published: February 2004

Summary: Automated electrochemical synthesis was used to create combinatorial libraries of mesoporous materials using tri‐block copolymers as structure directing agents (SDA). An example library of 56 ZnO samples was synthesized, varying concentrations (0–15 wt.‐%) of poly(ethylene oxide)‐block‐poly(propylene oxide)‐block‐poly(ethylene oxide) – EO20PO70EO20. High‐throughput photoelectrochemical screening for the measurement of water‐splitting photocatalysis identified peak performance at 3 wt.‐% of the SDA. Lamellar structures and disordered mesopores were observed by TEM and XRD.

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Integration of Combinatorial Synthesis, Rapid Screening, and Computational Modeling in Biomaterials Development
Authors: Smith Jack R. , Seyda Agnieszka , Weber Norbert , Knight Doyle , Abramson Sascha , Kohn Joachim
Published: February 2004

Summary: The advent of high‐throughput combinatorial synthesis techniques in drug discovery has stimulated efforts to apply these techniques to the discovery of biomaterials. To be of practical utility, combinatorial approaches to biomaterials design require (i) the availability of parallel synthesis techniques to generate libraries of polymers, (ii) efficient assays for the rapid characterization of biorelevant material properties, and (iii) computational methods to efficiently model different biological responses in the presence of polymers. Here we report the integration of these methodologies and illustrate the potential of this approach to accelerate the development of new biomaterials. The parallel synthesis of a library of 112 biodegradable polyarylates has been reported previously. This library was used to develop efficient screening techniques to determine biorelevant polymer properties (fibrinogen adsorption, gene expression in macrophages, growth of fetal rat lung fibroblasts (RLFs)). A Surrogate (semiempirical) Model was developed (i) to determine molecular‐scale polymer properties that correlate to various biological responses, and (ii) to predict fibrinogen adsorption and RLF growth on polymeric surfaces. For 38 out of 45 polymers, the model predicted the amount of fibrinogen adsorbed correctly within the error of the experimental measurements. The growth of rat lung fibroblasts was correctly predicted by the model for 41 out of 48 polymers. The correlation factor between the model's predicted values and the experimentally determined data was 0.54 ± 0.09 and 0.69 ± 0.12 for fibrinogen adsorption and RLF growth, respectively. The results presented here demonstrate the utility of combinatorial and computational approaches for the rational design of polymers for biomedical applications.

Design of the library of polyarylates, which are copolymers of a diacid and a diphenol. Chemical diversity was created by variations in the structure of the diacid (marked as “Y”) and the pendent chain (marked as “R”).

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Design of the library of polyarylates, which are copolymers of a diacid and a diphenol. Chemical diversity was created by variations in the structure of the diacid (marked as “Y”) and the pendent chain (marked as “R”).
Multiparameter High Throughput Characterization of Combinatorial Chemical Microarrays of Chemosensitive Polymers
Authors: Mirsky Vladimir M. , Kulikov Valentin , Hao Qingli , Wolfbeis Otto S.
Published: February 2004

Summary: High throughput characterization of combinatorial libraries demands a compromise between completeness of the study and reasonable investigation time. This compromise can be found by the development of test protocols consisting of the minimal number of the most informative measurements. Multiparameter high throughput characterization of sensitive materials is described. The parameters include response time, regeneration time, reversibility, reproducibility, sensitivity, linearity. The approach was applied for characterization of conductometric gas‐sensitive polymer materials.

Chemical microarrays prepared by electrochemical synthesis of polymers on platinum electrodes.

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Chemical microarrays prepared by electrochemical synthesis of polymers on platinum electrodes.
Sensors in Combinatorial Polymer Research
Authors: Potyrailo Radislav A.
Published: February 2004

Summary: This review highlights the broad potential of sensor technologies for combinatorial polymer research. Advances in components microfabrication, electronics, transducers, and data analysis in the area of sensors can stimulate the development of many more new concepts applicable for rapid polymer screening. These advances are already impacting on several phases in a typical combinatorial discovery cycle that include parallel synthesis of polymers, their performance testing, evaluation of properties, and processing of collected data. It is demonstrated that sensors provide an attractive addition to the infrastructure of the analytical instruments used for screening of intrinsic and performance polymer properties.

Impact of sensor technologies on the combinatorial discovery cycle.

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Impact of sensor technologies on the combinatorial discovery cycle.
The Codeposited Composition Spread Approach to High‐Throughput Discovery/Exploration of Inorganic Materials
Authors: van Dover Robert Bruce , Schneemeyer Lynn F.
Published: February 2004

Summary: We discuss the high‐throughput materials discovery/exploration paradigm in the context of inorganic materials. We emphasize the codeposited continuous composition spread approach, contrasting it with layered composition spreads and the discrete combinatorial approach to synthesis. The results of specific investigations on dielectrics are discussed in detail. The use of inorganic materials in thin film form entails some general advantages and disadvantages that will be discussed. We also contrast the considerations involved in the screening/discovery of new materials vis‐à‐vis reliable characterization of the composition dependence of properties.

Ternary plot of the relative dielectric constant in the ZrSnTiO system.

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Ternary plot of the relative dielectric constant in the ZrSnTiO system.
Gradient Polymer Layers by “Grafting To” Approach
Authors: Ionov Leonid , Zdyrko Bogdan , Sidorenko Alexander , Minko Sergiy , Klep Viktor , Luzinov Igor , Stamm Manfred
Published: February 2004

A new method for the preparation of ultrathin tethered polymer layers with gradually changing thickness was developed utilizing the “grafting to” approach. The grafting procedure allowed translation of the temperature gradient created in a heating stage into a gradient of polymer chain grafting density. The gradient tethered polymer layers demonstrated gradual changes in wetting properties and morphology transition from pinned micelles to a brush regime along the substrate.

Preparation of ultrathin tethered polymer layers with gradually changing thickness by utilizing a “grafting to” approach using a temperature gradient created on a heating stage.

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Preparation of ultrathin tethered polymer layers with gradually changing thickness by utilizing a “grafting to” approach using a temperature gradient created on a heating stage.
High‐Throughput Investigation of Polymerization Kinetics by Online Monitoring of GPC and GC
Authors: Hoogenboom Richard , Fijten Martin W. M. , Abeln Caroline H. , Schubert Ulrich S.
Published: February 2004

Summary: Gel permeation chromatography (GPC) and gas chromatography (GC) were successfully introduced into a high‐throughput workflow. The feasibility and limitations of online GPC with a high‐speed column was evaluated by measuring polystyrene standards and comparison of the results with regular offline GPC measurements. The reliability of the online GC characterization was investigated by monitoring the cationic ring‐opening‐polymerization of 2‐ethyl‐2‐oxazoline, whose polymerization kinetics were determined by both online and offline GC.

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A High‐Throughput Approach towards Tailor‐Made Water‐Soluble Metallo‐Supramolecular Polymers
Authors: Schmatloch Stefan , van den Berg Antje M. J. , Fijten Martin W. M. , Schubert Ulrich. S.
Published: February 2004

Summary: Automated parallel synthesis and high‐throughput screening has been proven to drastically speed up polymer and materials research. Here we present an automated parallel approach for investigation of the influences of different counter ions (chloride, bromide, acetate and sulfate) on the iron(II) mediated metallo‐supramolecular polymerization of bis(2,2′:6′,2″‐terpyrid‐4′‐yl)‐poly(ethylene oxide)179. The synthesized polymers were characterized by 1H NMR, UV‐vis and IR. The degree of polymerization has been estimated on the basis of concentration dependent viscosity measurements. The conversion as well as the degree of polymerization followed the order: bromide, chloride > sulfate ≫ acetate.

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Combinatorial Pulsed Laser Deposition of Pentacene Films for Field Effect Devices
Authors: Yamaguchi Jun , Itaka Kenji , Hayakawa Tomohiro , Arai Keiichiro , Yamashiro Mitsugu , Yaginuma Seiichiro , Koinuma Hideomi
Published: February 2004

Summary:Combinatorial pulsed laser deposition (PLD) technique has been applied to the fabrication of pentacene thin films for field effect devices. The pentacene films were fabricated by PLD with the Nd:YAG laser wavelength, fluence and the substrate temperature as combinatorial parameters. From the IR and UV‐vis absorption spectra and electrical properties of the films, the laser wavelength and fluence have been elucidated to be factors dominating the properties of the film.

Schematic diagram of a combinatorial pulsed laser deposition (PLD) system.

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Schematic diagram of a combinatorial pulsed laser deposition (PLD) system.
Scattering Measurements for High Throughput Materials Science Research
Authors: Norman Alexander I. , Cabral João T. , Karim Alamgir , Amis Eric J.
Published: February 2004

Summary: We present a high throughput X‐ray scattering study (SAXS/WAXS) of the formation and stability of the vesicle phase of a water soluble diblock copolymer. The vesicle shape and shell thickness were investigated as a function of block copolymer concentration and temperature. We were able to establish a growth in the SAXS peak as concentration increased, indicating a greater polymer concentration of vesicles. The effect of temperature was also investigated.

Library sample of a discrete concentration gradient of EO(6)BO(11) in water.

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Library sample of a discrete concentration gradient of EO(6)BO(11) in water.
Cover Picture: Macromol. Rapid Commun. 1/2004
Authors: Meier Michael A. R. , Hoogenboom Richard , Schubert Ulrich S.
Published: February 2004

Cover: A general workflow for combinatorial and high‐throughput polymer research, with examples, is shown. The cycle starts with the design of experiments (DoE), followed by automated polymer synthesis, high‐throughput screening, library preparation (thin films, dots and gradient libraries), property investigations and finally data mining. The background depicts polymer MALDI‐TOF MS data obtained during high‐throughput screening.

Details can be found in the Review by M. A. R. Meier, R. Hoogenboom, and U. S. Schubert* on page 21.
Theoretical study of beryllium (II) complexes using CATIVIC: New parametric method
Authors: Martínez Ramón , Brito Felipe , Araujo Mary Lorena , Ruette Fernando , Sierraalta Aníbal
Published: February 2004

Calculations of several beryllium complexes {[Be(H2O)n]2+(n= 1–4), [BeOH(H2O)n]+(n= 1–3), and [Be(OH)2(H2O)n] (n= 1, 2)} were carried out to compare different ab initio (density functional theory, MP2) and parametric (PM3(tm), CATIVIC) methods. Results show that the parametric method CATIVIC gives geometries and energies closer to the ab initio geometries than the PM3(tm) method due to the inclusion of the atomic excitation energies of the neutral atoms as well as the ions and to the dependence of the molecular parameters on the system charge. The molecular electronic density analysis of the BeO bonds shows that the Be–water interaction in the [Be(H2O)n]2+complexes can be considered as a closed‐shell interaction with a σ character in the bond while in the [Be(OH)2(H2O)n] complexes the Bewater bond have π character. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Study of the formamide–methanol dimer with ab initio and density functional theory methods
Authors: Fu Aiping , Du Dongmei , Zhou Zhengyu
Published: February 2004

For the first time, the structures and energies for the hydrogen bonding of a 1:1 complex formed between formamide and methanol molecules have been computed with various pure and hybrid density functional theory (DFT) and ab initio methods at varied basis set levels from 6‐31g to 6‐31+g(d,p). Five reasonable geometries on the potential energy surface of methanol and formamide system are considered and their relative stability is discussed. The infrared (IR) spectrum frequencies, IR intensities, and vibrational frequency shifts are reported. From the systematic studies, it is found that all the DFT methods selected here correctly compute the dimerization energies and geometries, with the B3P86 method predicting the hydrogen bond lengths relatively shorter and BPW91 yielding the interaction energies relatively lower. Finally, the solvent effects on the geometries of the formamide–methanol complexes have also been investigated using self‐consistent reaction field (SCRF) calculations with five different DFT methods at the 6‐31+g(d,p) basis set level. The results indicate that the polarity of the solvent has played an important role on the structures and relative stabilities of different isomers. Moreover, the basis set superposition error correction is critical to the interaction energies in the polar solvents. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Ab initio structural study of some substituted ibuprofen derivatives as possible anti‐inflammatory agents
Authors: Villa M. , Bounaim L. , Smeyers N. , Senent M. L. , Ezamarty A. , Smeyers Y. G.
Published: February 2004

The formation energies of a series of substituted derivatives in α‐position of ibuprofen (2‐p‐isobutyl‐phenyl‐propionic acid) are determined, at the ab initio level RHF/6‐311G** with full geometry optimization, in their neutral and anionic forms and in the gas phase and water solution to correlate their physical–chemical properties with their anti‐inflammatory activity. Conformational calculations on the acidic moiety were also performed on five of them. The ab initio methods foresee that all these molecules present two preferred conformations in which the substituting atom in α‐position is lying approximately in the aromatic ring plane, in contrast with the results obtained with semiempirical methods. In this article, the protonation energy in solution, the solvation energy, the HOMO energy of the neutral form, and the lipophilicity will be considered as possible factors of anti‐inflammatory activity. The protonation energy in solution, together with the lipophilicity, are verified to be good activity factors: The smaller the protonation energy and the lipophilicity, the larger the anti‐inflammatory activity. In contrast, the larger the solvation energy, the smaller the activity. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Common generating functions of complete harmonic oscillator wave functions and transformation brackets in D dimensions
Authors: Chaos‐Cador L. , Ley‐Koo E.
Published: February 2004

The separability of the Schrödinger equation for harmonic oscillators in D dimensions and in different coordinate systems (Cartesian, circular, spherical) makes possible the construction of common generating functions for the complete harmonic oscillator wave functions in the corresponding dimensions and coordinates. Explicit forms of such generating functions and their series expansions are presented, and one of their applications is illustrated through the evaluation of transformation brackets. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Orthogonal time‐of‐flight secondary ion mass spectrometric analysis of peptides using large gold clusters as primary ions
Authors: Tempez Agnès , Schultz J. A. , Della‐Negra S. , Depauw J. , Jacquet D. , Novikov A. , Lebeyec Y. , Pautrat M. , Caroff M. , Ugarov M. , Bensaoula H. , Gonin M. , Fuhrer K. , Woods Amina
Published: February 2004

Secondary ion mass spectrometry (SIMS) for biomolecular analysis is greatly enhanced by the instrumental combination of orthogonal extraction time‐of‐flight mass spectrometry with massive gold cluster primary ion bombardment. Precursor peptide molecular ion yield enhancements of 1000, and signal‐to‐noise improvements of up to 20, were measured by comparing SIMS spectra obtained using Au+ and massive Au4004+ cluster primary ion bombardment of neat films of the neuropeptide fragment dynorphin 1–7. Remarkably low damage cross‐sections were also measured from dynorphin 1–7 and gramicidin S during prolonged bombardment with 40 keV Au4004+. For gramicidin S, the molecular ion yield increases slightly as a function of Au4004+ beam fluence up to at least 2 × 1013 Au4004+/cm2. This is in marked contrast to the rapid decrease observed when bombarding with ions such as Au5+ and Au9+. When gramicidin S is impinged with Au5+, the molecular ion yield decreases by a factor of 10 after a fluence of only 8 × 1012 ions/cm2. Comparison of these damage cross‐sections implies that minimal surface damage occurs during prolonged Au4004+ bombardment. Several practical analytical implications are drawn from these observations. Copyright © 2004 John Wiley & Sons, Ltd.
Analysis of uranium and isotopic ratio measurement in fish and marine invertebrates from the North Adriatic Sea by inductively coupled plasma mass spectrometry
Authors: Bettinelli Maurizio , Spezia Sandro , Minoia Claudio
Published: February 2004

Uranium analysis in fish, echinoderms and shellfish samples collected in the north part of the Adriatic Sea is presented. The aim of the work was to evaluate uranium concentrations in samples of this kind, and also to investigate possible contamination from depleted uranium (DU) in consequence of the war operations previously conducted in that area. DU contamination was checked by measuring the 235U/238U isotope ratio. The samples were dissolved according to the EPA 3052 procedure, and the determinations were performed by inductively coupled plasma mass spectrometry (ICP‐MS), optimized in order to perform isotope ratio measurements with good precision. The method was validated by evaluating the recovery from spiked samples; results in the range 93–107% were obtained. The isotope ratio measurement was evaluated in terms of accuracy and precision by analyzing the certified reference materials IAEA 326 and GBW 07305, and good agreement with the certified values was obtained here also. The concentration of uranium was higher in invertebrate samples than in fish (0.3–2 μg/g of U vs. 0.05–0.1 μg/g, respectively). The isotope ratio measurements for all the samples gave values very similar to the natural ratio, permitting exclusion of the presence of DU. Copyright © 2004 John Wiley & Sons, Ltd.