Large-scale coupled-cluster calculations

Coupled-cluster theory provides one of the most successful concepts in electronic-structure theory. This work covers the parallelization of coupled-cluster energies, gradients, and second derivatives and its application to selected large-scale chemical problems, beside the more practical aspects such as the publication and support of the quantum-chemistry package ACES II MAB and the design and development of a computational environment optimized for coupled-cluster calculations. The main objective of this thesis was to extend the range of applicability of coupled-cluster models to larger molecular systems and their properties and therefore to bring large-scale coupled-cluster calculations into day-to-day routine of computational chemistry. A straightforward strategy for the parallelization of CCSD and CCSD(T) energies, gradients, and second derivatives has been outlined and implemented for closed-shell and open-shell references. Starting from the highly efficient serial implementation of the ACES II MAB computer code an adaptation for affordable workstation clusters has been obtained by parallelizing the most time-consuming steps of the algorithms. Benchmark calculations for systems with up to 1300 basis functions and the presented applications show that the resulting algorithm for energies, gradients and second derivatives at the CCSD and CCSD(T) level of theory exhibits good scaling with the number of processors and substantially extends the range of applicability. Within the framework of the ’High accuracy Extrapolated Ab initio Thermochemistry’ (HEAT) protocols effects of increased basis-set size and higher excitations in the coupled- cluster expansion were investigated. The HEAT scheme was generalized for molecules containing second-row atoms in the case of vinyl chloride. This allowed the different experimental reported values to be discriminated. In the case of the benzene molecule it was shown that even for molecules of this size chemical accuracy can be achieved. Near-quantitative agreement with experiment (about 2 ppm deviation) for the prediction of fluorine-19 nuclear magnetic shielding constants can be achieved by employing the CCSD(T) model together with large basis sets at accurate equilibrium geometries if vibrational averaging and temperature corrections via second-order vibrational perturbation theory are considered. Applying a very similar level of theory for the calculation of the carbon-13 NMR chemical shifts of benzene resulted in quantitative agreement with experimental gas-phase data. The NMR chemical shift study for the bridgehead 1-adamantyl cation at the CCSD(T) level resolved earlier discrepancies of lower-level theoretical treatment. The equilibrium structure of diacetylene has been determined based on the combination of experimental rotational constants of thirteen isotopic species and zero-point vibrational corrections calculated at various quantum-chemical levels. These empirical equilibrium structures agree to within 0.1 pm irrespective of the theoretical level employed. High-level quantum-chemical calculations on the hyperfine structure parameters of the cyanopolyynes were found to be in excellent agreement with experiment. Finally, the theoretically most accurate determination of the molecular equilibrium structure of ferrocene to date is presented.

Einflüsse von Folienqualität und Blister-Design auf die Funktionalität von Blisterverpackungen

Ziel dieser Arbeit ist die Untersuchung der Einflüsse von Blister-Design und Folienqualität auf die Funktionalität von Blisterverpackungen. Hierzu werden analytische Methoden mittels Interferometrie, IR-Spektroskopie, Betarückstreuverfahren, Wirbelstromverfahren und Impedanzspektroskopie entwickelt, die zur quantitativen Bestimmung von Heißsiegellacken und Laminatbeschichtungen von Aluminium-Blisterfolien geeignet sind. Ein Vergleich der Methoden zeigt, dass sich das Betarückstreuverfahren, die Interferometrie und IR-Messungen für die Heißsiegellackbestimmung, die Interferometrie und das Wirbelstromverfahren für die Bestimmung von Kunststofflaminaten eignen.rnIm zweiten Abschnitt der Arbeit werden Einflüsse des Heißsiegellack-Flächengewichtes von Deckfolien auf die Qualität von Blisterverpackungen untersucht. Mit Zunahme des Flächengewichtes zeigt sich eine Erhöhung der Siegelnahtfestigkeit aber auch der Wasserdampfdurchlässigkeit von Blistern. Die untersuchten Heißsiegellacke zeigen Permeationskoeffizienten vergleichbar mit Polyvinylchlorid. In Untersuchungen zur Siegelprozessvalidität zeigt das Heißsiegellack-Flächengewicht nur geringfügige Auswirkungen auf diese. rnIm dritten Abschnitt der Arbeit werden Einflüsse des Blister-Designs auf die Benutzerfreundlichkeit von Blisterverpackungen durch eine Handlingstudie untersucht. Variationen der Öffnungskräfte von Durchdrück-Blistern wirken sich deutlich auf die Bewertungen der Blister durch die Probanden aus. Während die meisten Probanden alle getesteten Durchdrück-Blister innerhalb der Testdauer von 4 Minuten öffnen können (>84%), treten beim Peel-Blister und Peel-off-push-through-Blister deutlich mehr Handlingprobleme auf. Die Handlingprobleme korrelieren mit dem Alter, der Lebenssituation, der gesundheitlichen Verfassung und der Sehfähigkeit der Probanden. rn

Studio sulla distribuzione dell'inquinamento da idrocarburi clorurati nelle falde della Provincia di Ferrara.

La Provincia di Ferrara ha avuto (ed ha tuttora) sul suo territorio, insediamenti produttivi di varia natura, che nel tempo hanno fatto uso di idrocarburi alifatici clorurati, per scopi diversi: solventi, sgrassanti, refrigeranti, supporti chimici e farmaceutici, ecc. Soprattutto nei decenni passati, a causa di normative poco restringenti sull’uso e sullo smaltimento di questi composti, si sono verificate le condizioni per provocare l’inquinamento delle falde del territorio provinciale. Nel corso degli anni, si sono svolti studi di diverso carattere, finalizzati ad individuare e caratterizzare siti (o raggruppamenti di siti) contaminati da idrocarburi clorurati. In questo lavoro si è allargata l’attenzione a tutti i siti presenti nel territorio definito dai limiti amministrativi della Provincia di Ferrara, che, nell‘arco temporale 2000 – 2015, hanno evidenziato contaminazioni da CAHs nell’acquifero superficiale A0 e/o nell’acquifero confinato A1. Si sono create, quindi, carte di distribuzione dei siti inquinati su scala provinciale, analizzandone principalmente caratteristiche idrogeologiche e variazioni di distribuzione chimica nello spazio e nel tempo, in relazione agli studi di caratterizzazione ed a eventuali messe in sicurezza e/o bonifiche. I dati necessari sono stati reperiti dagli atti amministrativi e dai relativi documenti tecnici, messi a disposizione dalla Provincia di Ferrara. L’attenzione è ricaduta in particolare sul cloruro di vinile (Vinyl Chloride, VC) ritrovato in alte concentrazioni e in un alto numero di siti. Il suo non utilizzo diretto nei processi produttivi in esame, ne esclude la presenza in qualità di contaminante primario, classificandolo come prodotto della degradazione di altri idrocarburi clorurati più complessi, in larga parte etileni clorurati. Si è inoltre appurato, come la presenza di VC non sia solo attribuibile a siti operanti nel settore metallurgico o chimico, ma riguardi in alcuni casi inquinamenti provocati da commercio o stoccaggio di carburanti, a cui, in passato, furono aggiunti solventi clorurati per migliorarne le caratteristiche chimico-fisiche. Si è concluso infine, come nel territorio della Provincia di Ferrara siano frequenti condizioni particolari, che favoriscono la degradazione di composti organo-clorurati complessi, ed agevolano l’accumulo di cloruro di vinile. Tali caratteristiche, sono state principalmente individuate nella diffusa presenza di livelli fini, anche torbosi, e nella altrettanto diffusa presenza di ambienti riducenti, non solo nel caso dell’acquifero confinato A1 ma anche nel caso dell’acquifero superficiale A0.

Design of a systematic approach to workplace exposure medical surveillance protocols

Current toxic tort cases have increased national awareness of health concerns and present an important avenue in which public health scientists can perform a vital function: in litigation, and in public health initiatives and promotions which may result. This review presents a systematic approach, using the paradigm of interactive public health disciplines, for the design of a matrix framework for medical surveillance of workers exposed to toxic substances. The matrix framework design addresses the required scientific bases to support the legal remedy of medical monitoring for workers injured as a result of their exposure to toxic agents. A background of recent legal developments which have a direct impact on the use of scientific expertise in litigation is examined in the context of toxic exposure litigation and the attainment of public health goals. The matrix model is applied to five different workplace exposures: dental mercury, firefighting, vinyl chloride manufacture, radon in mining and silica. An exposure matrix designed by the Department of Energy for government nuclear workers is included as a reference comparison to the design matrix. ^

The benzene metabolite p-benzoquinone forms adducts with DNA bases that are excised by a repair activity from human cells that differs from an ethenoadenine glycosylase.

Benzene is a ubitiquous human environment mental carcinogen. One of the major metabolites is hydroquinone, which is oxidized in vivo to give p-benzoquinone (p-BQ). Both metabolites are toxic to human cells. p-BQ reacts with DNA to form benzetheno adducts with deoxycytidine, deoxyadenosine, and deoxyguanosine. In this study we have synthesized the exocyclic compounds 3-hydroxy-3-N4-benzetheno-2'-deoxycytidine (p-BQ-dCyd) and 9-hydroxy-1,N6-benzetheno-2'-deoxyadenosine (p-BQ-dAdo), respectively, by reacting deoxycytidine and deoxyadenosine with p-BQ. These were converted to the phosphoamidites, which were then used to prepare site-specific oligonucleotides with either the p-BQ-dCyd or p-BQ-dAdo adduct (pbqC or pbqA in sequences) at two different defined positions. These oligonucleotides were efficiently nicked 5' to the adduct by partially purified HeLa cell extracts--the pbqC-containing oligomer more rapidly than the pbqA-containing oligomer. In contrast to the enzyme binding to derivatives produced by the vinyl chloride metabolite chloroacetaldehyde, the oligonucleotides up to 60-mer containing p-BQ adducts did not bind measurably to the same enzyme preparation in a gel retardation assay. Furthermore, there was no competition for the binding observed between oligonucleotides containing 1,N6-etheno A deoxyadenosine (1,N6-etheno-dAdo; epsilon A in sequences) and these oligomers containing either of the p-BQ adducts, even at 120-fold excess. When highly purified fast protein liquid chromatography (FPLC) enzyme fractions were obtained, there appeared to be two closely eluting nicking activities. One of these enzymes bound and cleaved the epsilon A-containing deoxyoligonucleotide. The other enzyme cleaved the pbqA- and pbqC-containing deoxyoligonucleotides. One additional unexpected fact was that bulk p-BQ-treated salmon sperm DNA did compete effectively with the epsilon A-containing oligonucleotide for protein binding. This raises the possibility that such DNA contains other, as-yet-uncharacterized adducts that are recognized by the same enzyme that recognizes the etheno adducts. In summary, we describe a previously undescribed human DNA repair activity, possibly a glycosylase, that excises from DNA pbqC and pbqA, exocyclic adducts resulting from reaction of deoxycytidine and deoxyadenosine with the benzene metabolite, p-BQ. This glycosylase activity is not identical to the one previously reported from this laboratory as excising the four etheno bases from DNA.

Estudo da reação de epoxidação do óleo de soja em condição de remoção de calor máxima.

Óleo de soja epoxidado (OSE) é um produto químico há muito tempo utilizado como co-estabilizante e plastificante secundário do poli (cloreto de vinila) (PVC), ou seja, como um material que tem limitações na quantidade máxima que pode ser usada no composto de PVC. A sua aplicação como plastificante primário, ou seja, como o principal elemento plastificante no composto de PVC, e como base para outros plastificantes de fontes renováveis, tem aumentado nos últimos anos, principalmente devido a melhorias de desempenho e à redução do custo do OSE em comparação com plastificantes tradicionais. A reação de epoxidação do óleo de soja é bem conhecida e ocorre em duas fases líquidas, com reações em ambas as fases, e transferência de massa entre as fases. O processo industrial mais utilizado conta com formação in-situ do ácido perfórmico, através da adição gradativa do principal reagente, o peróxido de hidrogênio a uma mistura agitada de ácido fórmico e óleo de soja refinado. Industrialmente, o processo é realizado em batelada, controlando a adição do reagente peróxido de hidrogênio de forma que a geração de calor não ultrapasse a capacidade de resfriamento do sistema. O processo tem um ciclo que pode variar entre 8 e 12 horas para atingir a conversão desejada, fazendo com que a capacidade de produção seja dependente de investimentos relativamente pesados em reatores agitados mecanicamente, que apresentam diversos riscos de segurança. Estudos anteriores não exploram em profundidade algumas potenciais áreas de otimização e redução das limitações dos processos, como a intensificação da transferência de calor, que permite a redução do tempo total de reação. Este trabalho avalia experimentalmente e propõe uma modelagem para a reação de epoxidação do óleo de soja em condições de remoção de calor máxima, o que permite que os reagentes sejam adicionados em sua totalidade no início da reação, simplificando o processo. Um modelo foi ajustado aos dados experimentais. O coeficiente de troca térmica, cuja estimativa teórica pode incorrer em erros significativos, foi calculado a partir de dados empíricos e incluído na modelagem, acrescentando um fator de variabilidade importante em relação aos modelos anteriores. O estudo propõe uma base teórica para potenciais alternativas aos processos adotados atualmente, buscando entender as condições necessárias e viáveis em escala industrial para redução do ciclo da reação, podendo inclusive apoiar potenciais estudos de implementação de um reator contínuo, mais eficiente e seguro, para esse processo.

Plastisol gelation and fusion rheological aspects

This study deals with the rheological aspects of poly-vinyl chloride (PVC) plastisol gelation and fusion processes in foamable formulations. Here, such processes are simulated by temperature-programmed experiment (5 K min−1) in which complex viscosity components are continuously recorded. Nineteen samples based on a PVC-VAC (vinyl acetate 95/5) copolymer with 100 phr plasticizer have been studied, differing only by the plasticizer structure. The sample shear modulus increases continuously with temperature until a maximum, long time after the end of the dissolution process as characterized by DSC. The temperature at the maximum varies between 345 and 428 K with a clear tendency to increase almost linearly with the plasticizer molar mass, and to vary with the flexibility and the degree of branching of the plasticizer molecule. The shear modulus increase is interpreted in terms of progressive “welding” of swelled particles by polymer chain reptation. The plasticizer nature would mainly affect the friction parameter of chain diffusion.

A rea Sur de Chicago : proyecto Piloto de Notificaci on al P ublico : incluye las a reas de Chicago Heights, South Chicago Heights y Steger.

House Resolution (HR) 1010 adopted June 2004, encourages the Illinois EPA to establish a Right-to-Know Committee and to obtain citizens' input on the most effective and efficient means of providing notice to residents exposed to or potentially exposed to contamination from air, land or water. In keeping with the spirit of the resolution, Illinois EPA is conducting this pilot notification project with the assistance of the Illinois Department of Public Health and the Cook County Department of Public Health. This notice is precautionary, because of the potential for one or more sites to affect the groundwater quality in the area. There are many sites in the area that may have a potential for contaminating groundwater. The current notification has to do with information Illinois EPA has gathered in the course of investigating, monitoring and performing work on the landfill sites discussed below. These are located in the Chicago Heights/South Chicago Heights area, south of 26th Street and west of State Street (see attached map): Chicago Heights Refuse Depot, Triem Landfill and Fitzmar Landfill. A fourth landfill, Lobue, is adjacent to these, although Illinois EPA currently has very little information about that landfill. In 1987, vinyl chloride was detected in South Chicago Heights Well #3 at a level that was more than the Class I Groundwater Standard, which is 2 parts per billion. Investigation and sampling of monitoring wells at the landfill site near Well #3 showed higher concentrations of vinyl chloride (140-240 parts per million) in 1988. South Chicago Heights discontinued the use of Well #3 after this event and later stopped using all its wells and began purchasing water from Chicago Heights in 2000.

A rea Sur de Chicago : un iniciativo de alcanze para pruebas de pozos privados : Incluye las a freas de Chicago Heights, South Chicago Heights y Steger.

Areas of concern: This notification is based on information Illinois EPA has found while investigating, monitoring and working on two landfill sites in the Chicago Heights/South Chicago Heights area. Tests from groundwater and surface water at one landfill site showed levels of vinyl chloride greater than state Class I groundwater standards - the state standards that are designed to protect groundwater for use as drinking water. Vinyl chloride is from a family of chemicals known as volatile organic compounds (VOCs), which are common man-made chemicals found in cleaning solvents, gasoline and oil. These chemicals can travel in groundwater long distances from where they were spilled or dumped.

Community water supply well shooting/blasting near Hillcrest Subdivision, Lake County, Illinois.

The purpose of this fact sheet is to provide a summary of literature research on the use of well "shooting" or blasting technology in Northern Illinois. Water well shooting or blasting is done to increase water yield from a sandstone aquifer for a particular water supply well ... The Lake County Health Department (LCHD) detected a chemical, vinyl chloride -- from a family of chemicals known as volatile organic compounds (VOCs) -- in some private wells in the unincorporated Hillcrest Subdivision near Wauconda, through routine well testing done in the fall of 2003. The LCHD presented these findings to the public at a January 13, 2004 meeting. The concern was raised at the public meeting that recent subsurface water well "shooting" or blasting techniques, performed in the deep sandstone aquifer (800 to 1,000 feet below ground surface), in the borehole of a community water supply (CWS) well in the area, might have impacted the shallow aquifer in such a way as to contribute to private well contamination under investigation in the Hillcrest Subdivision.

Kinetic and phylogenetic characterization of an anaerobic dechlorinating microbial community

The reductive dechlorination (RD) of tetrachloroethene (PCE) to vinyl chloride (VC) and, to a lesser extent, to ethene (ETH) by an anaerobic microbial community has been investigated by studying the processes and kinetics of the main physiological components of the consortium. Molecular hydrogen, produced by methanol-utilizing acetogens, was the electron donor for the PCE RD to VC and ETH without forming any appreciable amount of other chlorinated intermediates and in the near absence of methanogenic activity. The microbial community structure of the consortium was investigated by preparing a 1 6S rDNA clone library and by fluorescence in situ hybridization (FISH). The PCR primers used in the clone library allowed the harvest of 16SrDNA from both bacterial and archaeal members in the community. A total of 616 clones were screened by RFLP analysis of the clone inserts followed by the sequencing of RFLP group representatives and phylogenetic analysis. The clone library contained sequences mostly from hitherto undescribed bacteria. No sequences similar to those of the known RD bacteria like 'Dehalococcoides ethenogenes' or Dehalobacter restrictus were found in the clone library, and none of these bacteria was present in the RD consortium according to FISH. Almost all clones fell into six previously described phyla of the bacterial domain, with the majority (56(.)6%) being deep-branching members of the Spirochaetes phylum. Other clones were in the Firmicutes phylum (18(.)5%), the Chloroflexi phylum (16(.)4%), the Bacteroidetes phylum (6(.)3%), the Synergistes genus (11(.)1%) and a lineage that could not be affiliated with existing phyla (11(.)1%). No archaeal clones were found in the clone library. Owing to the phylogenetic novelty of the microbial community with regard to previously cultured microorganisms, no specific microbial component(s) could be hypothetically affiliated with the RD phenotype. The predominance of Spirochaetes in the microbial consortium, the main group revealed by clone library analysis, was confirmed by FISH using a purposely developed probe.

A new polymeric flame retardant additive for vinyl polymers

Diethyl allyl phosphate (DEAP) monomer has been synthesized, and characterized, using H-1 NMR and direct ionization mass spectrometric (DI-MS) techniques. It was free-radically polymerized to yield the poly(diethyl allyl phosphate) (PDEAP). The direct pyrolysis-mass spectrometric (DP-MS) analysis of the PDEAP revealed that it undergoes thermal degradation to yield mainly the monomer. Utility of PDEAP as a potent flame-retardant additive in polystyrene (PS) and poly(methyl methacrylate) (PMMA) has also been established.

SYNTHESIS AND CHARACTERIZATION OF HYPERBRANCHED VINYL POLYMERS FROM RAFT POLYMERIZATION OF AN ASYMMETRIC DIVINYL MONOMER

Hyperbranched vinyl polymers were prepared by reversible addition-fragmentation chain transfer ( RAFT) polymerization of a styrenic asymmetric divinyl monomer. This was achieved by using cumyl dithiobenzoate or S-dodecyl-S'-(alpha,alpha'-dimethyl-alpha ''-acetic acid) trithiocarbonate as the chain transfer agent, 1,1'-azobis(cyclohexanecarbonitrile) or thermal initiation as a source of radicals. Cross-linking was inhibited by a rapid RAFT-based equilibrium between active propagation chains and dormant species, and thus a hyperbranched polymer with a monomer conversion as high as 80% was obtained. The hyperbranched structure and properties of the resultant polymers were characterized by a combination of H-1-NMR spectroscopy and a triple detection size exclusion chromatography (TRI-SEC). The hyperbranched vinyl polymer has a broad molecular weight distributions and a low Mark-Houwink exponent alpha value compared with the linear counterpart.

Reversible addition-fragmentation chain transfer mediated radical polymerization of asymmetrical divinyl monomers targeting hyperbranched vinyl polymers

Reversible addition-fragmentation chain transfer (RAFT) mediated radical polymerizations of allyl methacrylate and undecenyl methacrylate, compounds containing two types of vinyl groups with different reactivities, were investigated to provide hyperbranched polymers. The RAFT agent benzyl dithiobenzoate was demonstrated to be an appropriate chain-transfer agent to inhibit crosslinking and obtain polymers with moderate-to-high conversions. The polymerization of allyl methacrylate led to a polymer without branches but with five- or six-membered rings. However, poly(undecenyl methacrylate) showed an indication of branching rather than intramolecular cycles. The hyperbranched structure of poly(undecenyl methacrylate) was confirmed by a combination of H-1, C-13, H-1-H-1 correlation spectroscopy, and distortionless enhancement by polarization transfer 135 NMR spectra. The branching topology of the polymers was controlled by the variation of the reaction temperature, chain-transfer-agent concentration, and monomer conversion. The significantly lower inherent viscosities of the resulting polymers, compared with those of linear analogues, demonstrated their compact structure,