bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Resolution Photoelectron Spectroscopy and ab initio Quantum Chemistry
Authors: Willitsch Stefan , Wüest Andrea , Merkt Frédéric
Published: June 2006

The resolution that can be achieved by photoelectron spectroscopy has been continually improved over the past 50 years and is now sufficiently high for the rovibronic energy level structure of polyatomic molecular cations to be measured accurately. Ionisation potentials, molecular constants, and in some cases the potential energy surfaces of both the neutral and the ionic states connected by the photoionising transitions can be extracted from photoelectron spectra and used to test ab initio quantum chemical calculations. Ab initio quantum chemistry represents an essential tool to assign photoelectron spectra and to rationalise the experimental observations. Because either the neutral or the ionised species, or even both, connected by a photoionising transition possesses at least one unpaired electron, photoelectron spectroscopy represents a very convenient method to study openshell molecules. Unfortunately, much fewer highly accurate ab initio quantum chemical calculations have been reported on open-shell than on closed-shell molecules, and such calculations would be desired to assist in the interpretation of photoelectron spectra. This contribution illustrates the fruitful interplay between ab initio quantum chemistry and photoelectron spectroscopy with examples chosen from our recent work on the photoelectron spectra of the rare gas dimers and of small polyatomic hydrides and hydrocarbons. It also briefly reviews the experimental progress that makes it possible today to measure the fine and hyperfine structure in molecular ions by experimental techniques closely related to photoelectron spectroscopy.
Theoretical Chemistry: Molecular Spectroscopy and Dynamics
Authors: Mariotti Fabio , Quack Martin , Willeke Martin , Stohner Jürgen
Published: June 2006

We provide a short review of the scientific meeting defined by the title of this article, which may at the same time serve as a compact review of the field with a substantial number of references to recent work. Exciting new developments in experiments on high-resolution molecular spectra
and their analysis as well as new theoretical developments in the calculations of such spectra and the related time-independent and time-dependent quantum dynamics of molecules have led to new answers but also to new questions in the fields of molecular kinetics, molecular reaction dynamics,
molecular chaos and statistical mechanics as well as fundamental symmetries in molecular processes. Particular stress is placed on fundamental aspects and new directions.
Quantum Chemistry 'Without Orbitals' – An Old Idea and Recent Developments
Authors: Wesolowski Tomasz A.
Published: June 2006

The role of one-electron functions known as orbitals in various theoretical methods used to describe molecules and complex materials at a quantum mechanical level is outlined in a historical perspective. A hierarchy consisting of three types of general formalism, ordered according to
the importance of orbital-dependent expressions in the total energy, is presented. Two such formalisms, less known to the general chemistry community, are discussed in detail together with their recent applications in modelling complex systems: a) the orbital-free formulation of density functional
theory, which does not use orbitals at all and which can be seen as the modern realization of the original ideas of Thomas and Fermi, and b) the density partitioning based formalism, in which the orbitals are used only for smaller parts of a larger system (subsystems). The emphasis is placed
on the second type of formalism, a topic of strong interest of our Geneva group.
Combined Spectroscopic/Computational Studies of Metal Centers in Proteins and Cofactors: Application to Coenzyme B12
Authors: Brunold Thomas C.
Published: June 2006

This article illustrates how the combined computational/spectroscopic methodology used in our studies of metal centers in proteins and cofactors can be applied to vitamin B12 and its biologically relevant derivatives. The B12 cofactors have long fascinated chemists
because of their complex structures and unusual reactivities in biological systems; however, their electronic absorption (Abs) spectra have remained largely unassigned. In this study, Abs, circular dichroism (CD), magnetic CD (MCD), and resonance Raman spectroscopic techniques are used to
probe the electronic excited states of various Co3+ Cbl species that differ with respect to their upper axial ligand. Spectroscopic data for each species are analyzed within the framework of time-dependent density functional theory (TD-DFT) to assign the major spectral features
and to generate experimentally validated bonding descriptions. A simple model is presented that explains why the identity of the upper axial ligand has a major effect on the Co–Nax bond strength, whereas the lower axial ligand does not appreciably modulate the nature of the
Co–C bond. Impli- cations of these results with respect to enzymatic Co–C bond activation are discussed.
The Superior Therapeutic Properties of SOM230 Originate from Unique Structural Elements
Authors: Lewis Ian , Weckbecker Gisbert , Schmid Herbert A. , Lamberts Steven W.J. , Boerlin Viktor , Van der Hoek Joost , Bovermann Günter , Oberer Lukas , Pless Janos , Chandramouli Nagarajan , Bauer Wilfried , Albert Rainer , Bruns Christian
Published: June 2006

A rational drug design approach involving transposition of functional groups from SRIF into a reduced size cyclohexapeptide template has led to the discovery of SOM230, a novel, stable cyclohexapeptide somatostatin mimic which exhibits unique high affinity binding to human somatostatin
receptors (sst1-5). SOM230 has potent, long lasting inhibitory effects on growth hormone and insulin-like growth factor-1 release and is a promising development candidate currently under evaluation in phase II clinical trials.
Solvothermal Pathways Towards Transition Metal Oxides: Exploration and Optimisation
Authors: Michailovski Alexej , Patzke Greta R.
Published: June 2006

A systematic solvothermal access towards nanoscale molybdenum and tungsten oxides has been established. Firstly, a versatile precursor material is selected that offers an interesting spectrum of reaction products. In the next step, a wide variety of straightforward ionic additives are
screened to reveal and optimise all solvothermal pathways emerging from the precursor material. Finally, the appropriate precursor-additive combinations can be selected for further studies, such as nanorod design or the fabrication of novel materials.
New Catalysts and Receptors by Self-Assembly and Combinatorial Chemistry
Authors: Severin Kay
Published: June 2006

New methods that allow the generation of transition metal-based catalysts and receptors are discussed. It is shown that heterobimetallic, halogeno-bridged complexes are well-suited for screening assays in combinatorial catalysis. Metal catalysts with a structurally defined second coordination
sphere can be obtained by molecular imprinting with pseudo-substrate conjugates as exemplified by the substrate-, regio- and stereoselective reduction of ketones, catalyzed by immobilized ruthenium and rhodium complexes. Macrocyclic complexes, formed by self-assembly of organometallic complexes,
are shown to act as highly specific receptors for small cations and anions.
Analysis of Cannabis Material by Headspace Solid-Phase Microextraction Combined with Gas Chromatography-Mass Spectrometry
Authors: Ilias Yara , Rudaz Serge , Mathieu Patrick , Veuthey Jean-Luc , Christen Philippe
Published: June 2006

A headspace solid-phase microextraction method combined with gas chromatography/mass spectrometry was developed for the direct analysis of cannabis samples. Different parameters influencing the extraction of cannabinoids were studied and the optimised method was applied to the
analysis of plants from two different regions in Switzerland. Applied to cannabinoid concentrations, a principal components analysis was applied and demonstrated sample discrimination.
The Peptide Alkaloid Anachelin: NMR Spectroscopic Evidence for ?-Turn Formation in Aqueous Solution
Authors: Gademann Karl , Budzikiewicz Herbert
Published: June 2006

Anachelin, a complex secondary metabolite isolated from Anabaena cylindrica, possesses an unusual structure combining polyketide, peptide and alkaloid building blocks. This natural product was postulated to act as siderophore with catecholate and salicylate groups for putative
iron binding with the three-dimensional solution structure of anachelin remaining unknown. In this preliminary communication, the conformation of anachelin in aqueous solution is investigated. ROESY experiments revealed several interresidual NOEs characteristic of a compact, folded structure.
A ? -turn type structure of the central tripeptide sequence L-Thr-D-Ser-L-Ser structure involving D-Ser at position (i+1) and L-Ser at position (i+2) would be in agreement with the observed experimental data. In particular, this conformation of the free ligand would align
the putative metal binding groups (structural preorganization) and thus lower the free energy for Fe binding. As it is highly unusual to see such a small tripeptide fragment folding into a compact structure, it appears reasonable to assume that both the cationic tetrahydroquinolinium ring
as well as the trihydroxylated ?-amino acid contribute to the stabilization of the folded structure.
Pseudo-Prolines: Reversible Conformational Trap of Cyclosporin C as Novel Concept for Prodrug Design
Authors: Turpin Olivier , Mutter Manfred , Patiny Luc
Published: June 2006

The selective and reversible insertion of pseudo-proline (? Pro) systems in cyclosporin C (CsC) featuring different C(2) substituents at the oxazolidine ring and its impact on the conformational and biological properties is described. The presence of a 5-membered ring exerts drastic
effects upon the backbone conformation of CsC as demonstrated by NMR analysis. For example, the number of conformations, in particular in DMSO-d6, is strongly reduced and a cis 1-2 amide bond is induced when dialkylated at the C(2) position, resulting in a complete loss of the binding
capacity to its receptor CypA. The reversibility of ?Pro insertion allows the temporary introduction of conformational constraints representing a new strategy in pro-drug design.
New Institute of Chemistry and Biotechnology ICB at ZHW
Authors: Sonnleitner Bernhard , Bührer Heiner G. , Amrein Andreas H.
Published: June 2006

The recently founded Institute of Chemistry and Biotechnology ICB of the Zurich University of Applied Sciences, Winterthur, (ZHW) is the common platform for all R&D as well as service activities of the Abteilung für Chemie und Biologische Chemie CBC. The geographical
market of the ICB comprises primarily the Greater Zurich Area, eastern and central Switzerland. The customers are the small- and medium-sized enterprises of the region as well as larger corporations in Switzerland. The ICB benefits from its two pillars, chemistry and biotechnology, and a sound
networking of the institute at ZHW and in Switzerland. The structure of the ICB is clearly centered around three focal points of competence, namely Specialty Chemistry, (Bio)Chemical Measurement and Sensor Technique, and Chemical and Biochemical Engineering.
Development of a Robust Capillary Electrophoresis–Mass Spectrometer Interface with a Floating Sheath Liquid Feed
Authors: Bernet Pascal , Blaser Dominik , Berger Stefan , Schär Martin
Published: June 2006

The on-line combination of capillary electrophoresis (CE) with electrospray ionisation mass spectrometry (ESI-MS) has attracted major attention for the in-depth analysis of complex samples. However, CE-MS coupling is not straightforward. We present a novel coaxial sheath liquid CE-MS
interface, which is robust and can be used for both hyphenated techniques, liquid chromatography-mass spectrometry (LC-MS) and CE-MS, alternatively on the same mass spectrometer. The two separation techniques can be switched within minutes. To obtain a stable ion spray and avoid electrical
problems, the CE-power supply is used to produce the potential for the CE separation and the ESI sprayer tip simultaneously. The necessary sheath liquid is delivered by a pump which floats on the ion sprayer potential of the mass spectrometer, avoiding any current flow towards ground. The
sole parameter which has to be adjusted to adapt to different CE conditions is a variable resistor. Analytical applications such as peptide mixture analysis and drug screening are presented.
Synthesis and Biological Properties of Novel Fluoroprostaglandin Derivatives: Highly Selective and Potent Agonists for Prostaglandin Receptors
Authors: Matsumuraa Yasushi , Nakanob Takashi , Moria Nobuaki , Morizawab Yoshitomi
Published: June 2006

Synthesis of novel 7,7-difluoroprostacyclin and 15-deoxy-15,15-difluoro-PGF2? derivatives will be presented. These compounds show high affinity to prostaglandin receptors and potent biological activities.
The Importance of Fluorine in the Life Science Industry
Authors: Maienfisch Peter , Hall Roger G.
Published: June 2006

Fluorine-containing compounds are at the leading edge of many new developments in the life science industry. In recent years a steady increase in the number of fluorinated organic molecules reaching commercial status as crop protection products and pharmaceutical drugs has been observed:
in 1978, ca. 600 pesticides were known, but only approximately 25 (4%) contained fluorine. Today, fluorine-containing compounds account for more than 17% of all commercially available crop protection agents and many others are currently under development. The structures of the fluorine-containing
development compounds proposed for ISO common names between 1997 and 2002 are highlighted in this paper. In the pharmaceutical area around 220 fluorinated drugs were on the market in 1990, representing ca. 8% of all synthetic drugs. Six years later already more than 1500 fluorine-containing
drugs were under development. Fluorine-containing compounds have also been successful in the marketplace, such as the insecticides fipronil and lambda-cyhalothrin, the fungicides epoxiconazole and trifloxystrobin, the herbicides trifluralin and clodinafop, and the pharmaceutical blockbusters
Fluoxetine (Prozac®), Paroxetine (Paxil®), Ciprofloxacin (Cipro®) and Cisaprid (Propulsid®). This success is mainly due to the fact that selectively fluorinated compounds can exhibit dramatically improved potency when compared to the non-fluorinated analogues. The incorporation
of fluorine into a biologically active compound alters the electronic, lipophilic and steric parameters and can critically increase the intrinsic activity, the chemical and metabolic stability, and the bioavailability. The positive effects of fluorine on the biological efficiency is outlined
by three examples: in the chemical class of herbicidal thiatriazines, the presence or the absence of fluorine leads to dramatic effects on the biological activity; the metabolic stability and the pharmacokinetics of aminopyrazinone acetamide thrombin inhibitors were improved by the introduction
of fluorine, and in a novel class of insecticides/acaricides any modification of the gem -difluorovinyl group results in a strong decrease of biological activity.
Influence of Fluorination at Position 16 of Antibacterial Pristinamycins II#
Authors: Bacqué Eric
Published: June 2006

The influence of a fluorine atom at position C(16) of antibacterial pristinamycins II upon antibacterial, physico-chemical and pharmacokinetics properties is described.
Bioisosterism of Fluorine and Cyano as Indole Substituents. Theoretical, in vitro and in vivo Examination
Authors: Heinrich Timo , Böttcher Henning , Bartoszyk Gerd D. , Schwartz Harry , Anzali Soheila , März Joachim , Greiner Hartmut E. , Seyfried Christoph A.
Published: June 2006

Fluorine substitution modifies structural attributes and often induces unexpected effects. When substituting fluorine with cyano in position 5 of the indole in indole-butyl-amines, the properties of the compounds proved to be very comparable. In vitro target-profile, metabolism,
and in vivo activity in the ultrasonic vocalisation test indicate bioisosterism between the two substituents.
Chemo-Enzymatic Synthesis of Chiral Fluorine-Containing Building Blocks
Authors: Blaauw Richard H. , Ijzendoorn Denis R. , Cremers Jozef G.O. , Rutjes Floris P.J.T. , Broxterman Quirinus B. , Schoemaker Hans E.
Published: June 2006

Two complementary strategies for the synthesis of optically active fluorine-containing building blocks have been probed. The first strategy involves either the enzymatic resolution of fluorinated ?,?-disubstituted-?-amino acid amides, or the asymmetric hydrogenation
of fluorinated dehydroamino acids. The second strategy involves the transition metal-catalyzed introduction of fluorine-containing substituents onto olefin- or acetylene-containing ?-H-?-amino acids. These amino acids in turn are made optically active by enzymatic resolution of
the corresponding amides.
Selective Synthesis of Fluorinated Compounds: Process Development and Preparation of Fluorinated Compounds from Gram up to Kilogram Scale
Authors: Steiner Heinz , Meier Hans
Published: June 2006

The most versatile fluorination reactions for the preparation of up to kg amounts of fluorinated compounds are presented, i.e. the deoxofluorination of alcohols, oxo compounds and carboxylic acids using SF4, and the conversion of anilines to fluoro aromatics. Furthermore
the enantioselective catalytic fluorination of ? -ketoesters is highlighted. The option of outsourcing preparative fluorination is discussed.
Microfluidics-Based Reactors for Safe Fluorinations Using Elemental Fluorine
Authors: Turnbull Michael D. , Carter Neil B. , Dennison Stephen , Deacon Julie , Holley Richard
Published: June 2006

The design, development and initial operation of a new type of fluorine microreactor are described. Its use in agrochemical discovery chemistry is illustrated with simple examples of electrophilic fluorination.
gem-Difluorovinyl Derivatives as Insecticides and Acaricides
Authors: Pitterna Thomas , Böger Manfred , Maienfisch Peter
Published: June 2006

The insecticidal lead 1,1-difluorododec-1-ene was optimised. This compound has attractive insecticidal activity against tobacco budworm (Heliothis virescens), banded cucumber beetle (Diabrotica balteata), pea aphid (Aphis cracciovora), brown planthopper (Nilaparvata
lugens), and green rice leafhopper (Nephotettix cincticeps). Among different pharmacophore analogues, only 1,1-dichlorododec-1-ene and 1,1-difluoro-2-iodododec-1-ene showed weak insecticidal activity, whereas similar compounds such as 1-chloro-1-fluorododec-1-ene, 1-fluorododec-1-ene,
and 1,1-difluoro-2-bromododec-1-ene were inactive. Only bridge analogues with even-numbered carbon chains were active, for example 1,1-difluorodec-1-ene and 1,1-difluorotetradec-1-ene. Odd-numbered analogues such as 1,1-difluoronon-1-ene, 1,1-difluoroundec-1-ene, 1,1-difluorotridec-1-ene,
and 1,1-difluoro-pentadec-1-ene showed no activity. Modification of the tail group led to the analogues 12,12-difluorododec-11-enoic acid and its methyl ester, 12,12-difluorododec-11-en-1-ol, 1,1-difluoro-12-methoxydodec-1-ene, and 12,12-difluorododec-11-enylamine, all of which showed insecticidal
activity. 12,12-difluorododec-11-enoic acid methyl ester, 12,12-difluorododec-11-enoic acid, and 12,12-difluorododec-11-en-1-ol were also active against spider mites (Tetranychus ssp). Thus, in a first optimisation cycle, broad activity against insect pests and mites was discovered.
Two requirements, the gem-difluorovinyl pharmacophore and an even-numbered carbon chain, were found to be essential for activity. This latter requirement is in line with the proposed mode of action, which involves inhibition of the ? -oxidation of fatty acids in insect mitochondria.
In a second optimisation cycle, it was found that 6,6-difluorohex-5-enoic acid and its derivatives, such as acids, amides, and hydrazides, possess even superior properties as insecticides and acaricides. This led to the discovery of 6,6-difluorohex-5-enoic acid 2-[4-(4-trifluoromethylbenzyloxy)-phenoxy]-ethyl
ester (CGA 304'111). This compound showed excellent performance in field trials against a wide range of pests, as well as a more favourable toxicological profile than earlier derivatives. For a largescale synthesis of CGA 304'111, five different synthetic routes for 6,6-difluorohex-5-enoic
acid were developed. The best route involved radical addition of CBrClF2 to pent-4-enoic acid. Removal of bromine by hydrogenation, elimination of chloride and hydrolysis of the ester concluded this most efficient sequence. Thus, a practical synthesis for CGA 304'111 was identified,
which allowed the preparation of samples on a several 100 g scale.
Perfluorinated Brønsted 'Superacids': Powerful Catalysts for the Preparation of Vitamin E
Authors: Netscher Thomas , Bonrath Werner , Haas Alois , Hoppmann Eike , Pauling Horst
Published: June 2006

The key-step in the industrial synthesis of (all-rac)-?-tocopherol (synthetic vitamin E) is the condensation reaction of trimethylhydroquinone with the C20 building block isophytol. For this Friedel-Crafts-type reaction, perfluorinated NH- and CH-acidic compounds
(perfluoroalkyl(aryl)sulfonyl imides and methides) have been applied as excellent catalysts, preferably in biphasic solvent systems.
Simple and Efficient Industrial Preparation of Various Trifluoromethyl Ketones and Derivatives
Authors: Michel Dominique
Published: June 2006

Trifluoromethyl ketones are important tools in organic synthesis, useful especially for the production of complex fluorinated compounds. The preparation of ethyl 4,4,4-trifluoroacetoacetate and several attractive applications are described, as well as a new route leading to different
fluorinated pyruvaldehydes and some examples of applications.
Changes in the Activity and Selectivity of Herbicides by Selective Fluorine Substitution, Taking Bentranil and Classic® Analogues as Examples
Authors: Hamprecht Gerhard , Würzer Bruno , Witschel Matthias
Published: June 2006

The introduction of fluorine atoms into 2-phenyl-4H-3,1-benzoxazin-4-one (bentranil) led to sweeping changes in its herbicidal properties in some cases, and 5-fluoro-2-phenyl-4H-3,1-benzoxazin-4-one ('fluorobentranil') was found to be the most active compound. It can be prepared from
2-amino-6-fluoro-benzoic acid or by direct halogen exchange of 5-chloro-2-phenyl-4H-3,1-benzoxazin-4-one. The latter reaction was investigated on a pilot scale, including a high-temperature (350 °C) potassium fluoride halogen exchange without solvent. When sulfolane was used as a solvent,
a side reaction at 220 °C – partial decomposition to a diphenylether – could be prevented by addition of a small amount of a radical scavenger. Other intermediates with a pseudohalogen substitution were obtained by side-chain chlorination of suitable methylsulfanyl benzoic
acid precursors and halogen exchange. 'Fluorobentranil' shows good broad-leaf activity and selectivity on rice, cereals and maize. In a second case study, the fluoro-substituted anthranilic acids mentioned above were also found to be appropriate for synthesizing herbicidal sulfonylurea (SU)
compounds via Meerwein reaction of their aniline function. Methyl 2-[({[(4chloro-6-methoxy-2-pyrimidinyl)-amino]carbonyl}amino)sulfonyl]-6-fluorobenzoate is an example of a SU that is compatible with maize, whereas the unsubstituted Classic® analogue is not selective.
Radioactivity Buildup During Fuel Irradiation in Light Water Reactors (LWR)
Authors: Jeschki Wolfgang , Maxeiner Harald , Nordström Ake , Schweingruber Marc , Volmert Ben
Published: June 2006

Power production in LWRs is economic and very efficient. A by-product of the fission process, which generates the thermal power, is radioactivity associated with fission and activation nuclides. This article describes the ways in which radionuclides are produced and then dissipated
in the systems of a LWR. Radionuclides in and on the surface of components create radiation fields which can cause harm to workers. The article describes methods which help to minimize the buildup of these radiation fields. The difficulties in determining the radionuclide inventories for structural
materials in LWRs are discussed and appropriate code packages are discussed. The basic principles adopted in the context of treatment of radioactive waste are summarized, including an overview of typical conditioning strategies. Radiation protection issues are briefly described and methods
used to protect workers are discussed.
Recent Developments in the Purex Process for Nuclear Fuel Reprocessing: Complexant Based Stripping for Uranium/Plutonium Separation
Authors: Birkett J. Eddie , Carrott Michael J. , Fox O. Danny , Jones Chris J. , Maher Chris J. , Roube Cécile V. , Taylor Robin J. , Woodhead David A.
Published: June 2006

In order to recycle potentially valuable uranium and plutonium, the Purex process has been successfully used to reprocess spent nuclear fuel for several decades now at industrial scales. The process has developed over this period to treat higher burnup fuels, oxide as well as metal
fuels within fewer solvent extraction cycles with reduced waste arisings. Within the context of advanced fuel cycle scenarios, there has been renewed international interest recently in separation technologies for recovering actinides from spent fuel. Aqueous fuel processing research and development
has included further enhancement of the Purex process as well as the development of minor actinide partitioning technologies that use new extractants. The use of single cycle Purex solvent extraction flowsheets and centrifugal contactors are key objectives in the development of such advanced
Purex processes in future closed fuel cycles. These advances lead to intensified processes, reducing the costs of plants and the volumes of wastes arising. By adopting other flowsheet changes, such as reduced fission product decontamination factors, U/Pu co-processing and Pu/Np co-stripping,
further improvements can be made addressing issues such as proliferation resistance and minor actinide burning, without adverse effects on the products. One interesting development is the demonstration that simple hydroxamic acid complexants can very effectively separate U from Np and Pu in
such advanced Purex flowsheets.
Water Chemistry in Boiling Water Reactors – A Leibstadt-Specific Overview
Authors: Sarott Flurin-A.
Published: June 2006

The boiling water reactor (BWR) consists of two main water circuits: the water-steam cycle and the main cooling water system. In the introduction, the goals and tasks of the BWR plant chemistry are described. The most important objectives are the prevention of system degradation by
corrosion and the minimisation of radiation fields. Then a short description of the BWR operation principle, including the water steam cycle, the transport of various impurities by the steam, removing impurities from the condensate, the reactor water clean-up system, the balance of plant and
the main cooling water system, is given. Subsequently, the focus is set on the water-steam cycle chemistry. In order to fulfil the somewhat contradictory requirements, the chemical parameters must be well balanced. This is achieved by the water chemistry control method called 'normal water
chemistry'. Other additional methods are used for the solution to different problems. The 'zinc addition method' is applied to reduce high radiation levels around the recirculation loops. The 'hydrogen water chemistry method' and the 'noble metal chemical addition method' are used to protect
the reactor core components and piping made of stainless steel against stress corrosion cracking. This phenomenon has been observed for about 40 years and is partly due to the strong oxidising conditions in the BWR water. Both mitigation methods are used by the majority of the BWR plants all
over the world (including the two Swiss NPPs Mühleberg and Leibstadt).
,,Nachhaltige chemische Produktion" – Das 7. Freiburger Symposium 2005 im Rückspiegel
Authors: Käser Kurt
Published: June 2006

The Division Industrial Chemistry of the Swiss Chemical Society organizes periodically a two-day event for the post-graduate education of its members. This event is known as the Freiburger Symposium. This year it focussed on sustainable chemical production. The twelve talks covered
the following aspects: ethical needs for sustainability standards, the required, attained, and yet to be attained sustainability goals in chemical industry. Diverse case studies showed the highly developed awareness about the sustainability issue within the chemical community.
Liquid Metal Cooled Reactors
Authors: Wydler Peter
Published: June 2006

The long-term vision of a sustainable nuclear energy system is an important driver for the development of fast reactors because, apart from generating energy, these can serve as fuel-producing factories or transuranic waste burners. This key role in advanced fuel cycles and new, innovative
applications have revived the interest in various alternative fast reactor concepts such as liquid heavy metal and gas-cooled systems which, in the longer term, are perceived to have some advantages over the conventional sodium-cooled fast reactors. This article focuses on the liquid metal
cooled reactors. After a brief history of these reactors, the advantages and drawbacks of different liquid metal coolants are overviewed and, in the second part, current development trends are summarised, following the lines of the recent US initiative for a technology roadmap for Generation
IV nuclear energy systems.
Sustainability Aspects of Current and Future Electricity Supply Systems
Authors: Hirschberg Stefan , Dones Roberto
Published: June 2006

Approaches to comprehensive and consistent evaluation of sustainability of electricity supply systems including fossil, nuclear and renewable technologies are described. Sustainability can be assessed in a comparative manner using a comprehensive set of indicators derived using a variety
of methods. Examples of indicators are provided for a variety of current systems. Some trends for future systems are briefly described. Finally, conclusions are drawn on performance of the various technologies with respect to economic, ecologic and social criteria.
Nuclear Fuel Cycle Front End Chemistry
Authors: Blanpain Patrick , Capus Georges , Palussière Jean-Claude
Published: June 2006

A broad description of the main chemical processes involved at each main step of the nuclear fuel cycle, from uranium mining to nuclear grade uranium oxide preparation for nuclear fuel fabrication is provided.
Zirconium Alloys for Fuel Element Structures
Authors: Bart Gerhard , Bertsch Johannes
Published: June 2006

Today more than 400 light water power reactors (LWRs) operate worldwide providing approximately 17% of the world's electricity demand. One important component for their successful operation is the fuel tube, made out of a zirconium alloy. A huge number of out-of-pile and in-pile experiments
have been performed to improve step by step the fuel for higher burn-up and to reduce the failure rates of fuel pins close to zero. The influencing parameters for excellent or poor cladding behaviour are numerous and sometimes counteract each other. The process of cladding corrosion is slow,
difficult to follow, the mechanistic understanding at best incomplete. A vast amount of literature documents the abundant tests and comes up with hypotheses and models for the materials behaviour. PSI has supported for the past 20 years the development of high burn-up fuel cladding by microstructural
research studies and service work in post-irradiation examination of test pins. This article reviews the development of the cladding tubes, focussing on the chemical and materials science aspects.
Mass Spectrometry of Oligonucleotides
Authors: Monn Selina T.M. , Tromp Jan M. , Schürch Stefan
Published: June 2006

Within the past decade mass spectrometry has undoubtedly consolidated its role as a major player in modern bioanalysis. Mass spectrometry of oligonucleotides is an evolving field that has not reached its culmination point yet, as many aspects of oligonucleotide dissociation in gas phase
still need to be clarified. Research in our group is focused on the elucidation of the dissociation mechanisms of oligonucleotides and their analogs and on the characterization of metal–oligonucleotide complexes by tandem mass spectrometry in order to gain structural information. Here,
we present the dissociation mechanism of RNA and an example for the characterization of metal–oligonucleotide complexes.
Structure Determination of Catalytic RNAs and Investigations of Their Metal Ion-Binding Properties
Authors: Erat Michèle C. , Sigel Roland K.O.
Published: June 2006

Naturally occurring RNA molecules exhibit many unexpected and fascinating properties in living cells such as protein synthesis and transport, regulation of metabolic functions, and catalytic cleavage reactions. To understand this functional diversity, a detailed knowledge of RNA structure
and metal ion-binding properties is crucial. In our research group, we address these problems by combining various biochemical, analytical and spectroscopic techniques. A large part of our work is devoted to the structure determination of catalytic RNA molecules, i.e. ribozymes, by
NMR. Based on the three-dimensional structure, further experiments are carried out to understand in detail the effects of different metal ions on the local and global structure, as well as catalysis itself.
Searching for Nucleic Acid Alternatives
Authors: Eschenmoser Albert
Published: June 2006

"Back of the envelope" methods have their place in experimental chemical research; they are effective mediators in the generation of research ideas, for instance, the design of molecular structures. Their qualitative character is part of their strength, rather than a drawback for the
role they have to play. Qualitative conformational analysis of oligonucleotide and other oligomer systems on the level of idealized conformations is one such method; it has played a helpful role in our work on the chemical etiology of nucleic acid structure. This article, while giving a short
overview of that work, shows how.
DNA with Artificial Base Pairs
Authors: Hunziker Jürg , Mathis Gérald
Published: June 2006

The introduction of a single base pair with the electronically complementary base surrogates phenyl- (P) and pentafluorophenyl-deoxyriboside (F5) into DNA oligonucleotides leads to a strong decrease in duplex stability. Longer stretches with alternating P-F5
pairs can lead to duplexes with increased stability as compared to their counterparts with natural A-T base pairs. Optimization of the steric and electronic properties of the P-F5 pair by replacing the phenyl residue with naphthalene, anisole or thioanisole
leads to an increase in stability. Complementary charge distribution thus represents a novel design principle for artificial DNA base pairs. These results also highlight the importance of favorable intrastrand stacking interactions in the thermodynamic stabilization of oligonucleotide duplexes.
A combination with favorable interstrand stacking could lead to a set of orthogonal, non-hydrogen bonded base pairs. Such artificial pairing systems could be used in many ways. By gradually changing the composition of linearly stacked artificial bases interesting electronic, photophysical
and magnetic properties could result. The quasi one-dimensional arrangement of charge transfer complexes might pave the way for applications of the nucleic acid scaffold in material science.
Oligonucleosides with Integrated Backbone and Base: Foldamers with a Novel Architecture
Authors: Vasella Andrea T.
Published: June 2006

Dinucleoside and tetranucleoside analogues with integrated backbone and nucleobase represent a novel type of oligonucleotide foldamers. They are characterized by a linker between C(5?) of one nucleoside moiety and C(8) of an adjacent adenosine, or C(6) of an adjacent uridine.
Solutions in chloroform or chloroform/DMSO of these partially protected di-, or tetranucleoside analogues associate. The strength of the association depends on the nature of the linker, the presence, or absence of a hydroxymethyl group on the terminal nucleobase, other protecting groups, and
intramolecular hydrogen bonds. The thiomethylene-linked dimers were studied in detail; one of them associates strongly enough that a melting temperature can be determined, evidencing base stacking in chloroform solution. Some dimers form organogels. Two 2?,3?-O-isopropylidene protected
self-complementary tetramers were prepared. Their duplexes are conformationally homogeneous. One of the tetramers was characterised in detail; it associates via hydrogen bonds of the Watson-Crick type to form a partial A-type helix with all bases in a syn-conformation and a rather
large twist angle. Also studied were di- and tetranucleotide analogues possessing an all-carbon linker; they were derived from (hydroxy)propynylene linked dimers by deoxygenation, partial reduction to the (E)- and (Z)-propenylene linked analogues, and further hydrogenation to
propanylene-linked analogues. The propargylic hydroxy group forms an intramolecular hydrogen bond to N(3) of the adenine moiety of the same unit; the resulting conformers associate weakly. Deoxygenation leads to foldamers that associate much more strongly. A (Z)-propenylene-linked dimer
also associates strongly, its (E) isomer less so, and the propanylene-linked analogues associate weakly. The results show that backbone-base integration defines a novel structural relation between backbone and nucleobases that favours selective pairing and leads to oligonucleotide foldamers.
DNA Mimics Containing Non-Nucleosidic Base Surrogates
Authors: Langenegger Simon M. , Bianké Gapian , Tona Rolf , Häner Robert
Published: June 2006

Chemically modified nucleic acids find widespread use as tools in research, as diagnostic reagents and as pharmaceutical compounds. While the major efforts in the past concentrated on the generation of sugar-based nucleotide analogues, the potential of non-nucleosidic and non-hydrogen
bonding building blocks is largely untouched to date. Such derivatives may have an impact in the fields of materials and genetic research. In this paper, some recent findings of our work in this area are highlighted.
In-Strand Metallated Nucleic Acids – Novel Bioinorganic Constructs
Authors: Constable Edwin C. , Chaurin Valérie , Housecroft Catherine E. , Wirth Amina
Published: June 2006

Synthetic strategies have been developed for the preparation of in-chain metallated oligonucleotides, in which the oligonucleotide sequence is interrupted by a metal-containing motif. In our work, oligopyridine metal-binding domains are used and approaches are outlined using both labile
and non-labile metal centres.
Process Optimisation Based on Large Databases of Routinely Monitored Industrial Process Data
Authors: Kovar Karin , Friedli Thomas K. , Roubicek Dusan , Langenegger David S. , Keller Markus , Meyer Hans-Peter
Published: June 2006

Huge amounts of data are routinely logged and stored during the monitoring of biotechnological production processes. A concept is described to extract and analyse the information these data contain and to subsequently apply it for process improvement. In total, roughly 100,000 time
series of raw and derived signals which stemmed from 173 high-cell-density processes with recombinant microorganisms at 50 m3 scale (working volume) were processed. As is often the case, no mathematical process models were readily available and therefore data-driven, computer-intensive
methods were applied. These endeavours helped to stimulate a change in manufacturing strategy, which in turn has led to an increase in the final product titre of 26% on average.
A Study of the Physiological Response of Pichia pastoris Growing in a Continuous Culture to an Induced Stress Situation
Authors: Hyka Petr , Paulová Leona , Egger Manuel , Melzoch Karel
Published: June 2006

During our work, flow cytometry was used for a study of the influence of cultivation conditions on a physiological state, mainly on the viability and vitality of the recombinant Pichia pastoris strain producing ?-galactosidase. The fluorescent dyes propidium iodide and bis-(1,3-dibutylbarburic
acid) trimethine oxonol were used for the determination of the structural integrity and the membrane potential of Pichia pastoris cells, respectively. First the staining procedures were optimised and adapted for the Pichia pastoris yeast cells and later applied in a lab-scale
continuous cultivation. Stained samples were analysed with the flow cytometer PAS III Partec or the epifluorescence microscope Nikon Eclipse E400. The following conditions were found to be optimum for the staining of Pichia pastoris cells: 57 ?g/ml propidium iodide in the sample,
5 min incubation time; 2 ?g/ml bis-(1,3-dibutylbarburic acid) trimethine oxonol in the sample, 20 min incubation time. The optimised staining methods were employed in a study of stress-induced physiological response to change of substrate from glycerol to methanol in a glycerol steady state
growing culture of Pichia pastoris yeast. During the first 5 h of the transitional state an accumulation of methanol in the culture broth was accompanied by a decreasing concentration of biomass and an increasing amount of cells stained with propidium iodide and bis-(1,3-dibutylbarburic
acid) trimethine oxonol. After the adaptation phase the amount of cells stained with propidium iodide and bis-(1,3-dibutylbarburic acid) trimethine oxonol reached steady levels of 2% and 5%, respectively.
The Influence of Fatty Acids and their Derivatives on the Growth of Kluyveromyces, Saccharomyces, and Candida Species
Authors: Bartošová Eva , Špičková Zdeňka , Pospíšilová Olga , Šmidrkal Jan , Filip Vladimír
Published: June 2006

The antifungal properties of medium-chain fatty acids and their esters with glycerol were investigated. Fatty acid chain lengths of ten to twelve carbon atoms were examined, namely decanoic, undecanoic and dodecanoic acids and their 1-monoglycerides.Kluyveromyces marxianus var.
marxianus, Saccharomyces cerevisiae and Candida maltosa were used as indicator yeast strains. Inhibition of yeast growth was detected using spectrophotometry, agar plates, flow cytometry, and microscopy. It was observed that the inhibitory effects decreased with increasing
chain length. The minimum inhibitory concentration of fatty acids and 1-monoglycerides was found to vary between 0.05 and 0.10 mg/ml. The most sensitive yeast strain was Saccharomyces cerevisiae. Kluyveromyces marxianus var. marxianus and Candida maltosa were less sensitive
to the antimicrobial effect of tested substances. Knowledge of these properties of these compounds brings new alternatives for food preservation.
Computational Chemistry for Elucidating Protein Function: Energetics and Dynamics of Myoglobin–Ligand Systems
Authors: Nutt David R. , Banushkina Polina , Meuwly Markus
Published: June 2006

State-of-the-art computational methodologies are used to investigate the energetics and dynamics of photodissociated CO and NO in myoglobin (Mb···CO and Mb···NO). This includes the combination of molecular dynamics, ab initio MD, free
energy sampling, and effective dynamics methods to compare the results with studies using X-ray crystallography and ultrafast spectroscopy metho ds. It is shown that modern simulation techniques along with careful description of the intermolecular interactions can give quantitative agreement
with experiments on complex molecular systems. Based on this agreement predictions for as yet uncharacterized species can be made.
Laborpraktikum in Chemischer Technologie – Eine Dienstleistung der HTA-FR. Ein Beitrag an die Ausbildung von Chemikantenlehrlingen
Authors: Käser Kurt
Published: June 2006

For the past six years the Berufsschule Aarau has commissioned the School of Engineering and Architecture Fribourg to provide a practical training course in chemical technology to their third year students. During five blocks, three days each, the students work on specific topics
relevant to chemical manufacturing. One further day is spent on learning about practical data handling. The program aims to foster a deeper understanding of theoretical concepts, to enlarge professional experience and finally to develop the student's ability to work in small groups.
Computational Molecular Science for the Nutritional Industry
Authors: Grigorov Martin G.
Published: June 2006

The implementation of quantitative models of real phenomena that are evolved on computational devices has become a common practice in science and engineering in the last 50 years. The major advantage of this technology is the possibility to process large amounts of data in relatively
short times. In this review the major techniques of computational molecular science as applied in the industry of life sciences are reviewed. Further these techniques are discussed in view of their documented impact on the research and development workflow, with real illustrative examples
taken from the nutrition and food industry. Computational molecular sciences have now come of age and, when deployed knowledgably, are shown to be able to generate intelligent hypotheses for project advancement, to lower attrition rate and to ultimately reduce research and development costs
and to shorten the time-to-market cycle. The documented successes are however episodic and therefore efforts should be directed towards the development of standard reproducible protocols to use this technology.
Parity Violation in Chiral Molecules
Authors: Quack Martin , Stohner Jürgen
Published: June 2006

The current status of the computational approach to electroweak quantum chemistry which includes the parity violating weak nuclear interaction is briefly reviewed. After a short introduction and discussion of current experimental efforts in measuring parity violation in chiral molecules,
the general theoretical background and recent approaches predicting order of magnitude increases in parity violating potentials are outlined. The current results on these increased values, the role of biomolecular chirality, calculation of properties, use of density functional theory, anharmonic
vibrational and relativistic corrections, as well as a new isotope effect for isotopically chiral molecules are summarized.
Quantum Mechanical/Molecular Mechanical (QM/MM) Car-Parrinello Simulations in Excited States
Authors: Moret Marc-Etienne , Tapavicza Enrico , Guidoni Leonardo , Röhrig Ute F. , Sulpizi Marialore , Tavernelli Ivano , Rothlisberger Ursula
Published: June 2006

The combination of time-dependent density functional theory (TDDFT) for the description of excited states with a hybrid quantum mechanics/molecular mechanics (QM/MM) approach enables the study of photochemical processes in complex environments. Here, we present a short overview of recent
applications of TDDFT/MM approaches to a variety of systems including studies of the optical properties of prototypical organic and inorganic molecules in gas phase and solution, photoinduced electron transfer reactions in donor-bridge-acceptor complexes, and in situ investigations
of the molecular mechanisms of photoactive proteins. The application of TDDFT/MM techniques to a wide range of systems enables an assessment of the current performance and limitations of these methods for the characterization of photochemical processes in complex systems.