Forming behaviour analysis and constitutive modelling of Ti-6Al-4V at room temperature.

 A constitutive model was proposed in this thesis and a promising approach for accurate prediction of forming behaviour of high strength titanium alloy sheet metal forming at room temperature is presented. Outcomes showed a potential solution of cold roll forming of this material for aerospace and automotive structural applications.

Melhoria do pilar "manutenção planejada" da TPM através da utilização do RCM para nortear as estratégias de manutenção

O atual ambiente competitivo, onde baixo custo, alta qualidade e um grau crescente de customização são exigências para a sobrevivência das empresas, tem influenciado as ações dos profissionais de manutenção com vistas ao aprimoramento das políticas de manutenção. Como resultado, tem-se na área de manutenção industrial, uma grande quantidade de métodos, software, modelos e ferramentas de gestão disponíveis. Dentre eles, dois métodos se destacam: o RCM (Reliability Centered Maintenance ou Manutenção Centrada em Confiabilidade), de origem norte-americana, e a TPM (Total Productive Maintenance ou Manutenção Produtiva Total), de origem japonesa. A TPM promove a integração total entre homem, máquina e empresa, onde a manutenção dos meios de produção passa a constituir uma responsabilidade de todos. A utilização da TPM contempla a implementação de pilares de sustentação, sendo um deles, a manutenção planejada. Entretanto, a TPM não especifica a estratégia a ser adotada pela manutenção planejada. O RCM é uma metodologia lógica de procedimentos que objetiva estabelecer uma manutenção preditiva e preventiva para alcançar, de maneira efetiva e eficiente, os níveis de segurança e confiabilidade requeridas para cada equipamento. Considerando um ambiente com a TPM já implementada, o objetivo deste trabalho é a melhoria do pilar Manutenção Planejada da TPM através da utilização do RCM para nortear as estratégias de manutenção em empresas industriais. A sistemática proposta é ilustrada através de um estudo de caso na indústria de conformação de metais.

A 5'-3' exonuclease activity involved in forming the 3' products of histone pre-mRNA processing in vitro.

Histone RNA 3' processing in vitro produces one or more 5' cleavage products corresponding to the mature histone mRNA 3' end, and a group of 3' cleavage products whose 5' ends are mostly located several nucleotides downstream of the mRNA 3' end. The formation of these 3' products is coupled to the formation of 5' products and dependent on the U7 snRNP and a heat-labile processing factor. These short 3' products therefore are a true and general feature of the processing reaction. Identical 3' products are also formed from a model RNA containing all spacer nucleotides downstream of the mature mRNA 3' end, but no sequences from the mature mRNA. Again, this reaction is dependent on both the U7 snRNP and a heat-labile factor. Unlike the processing with a full-length histone pre-mRNA, this reaction produces only 3' but no 5' fragments. In addition, product formation is inhibited by addition of cap structures at the model RNA 5' end, indicating that product formation occurs by 5'-3' exonucleolytic degradation. This degradation of a model 3' product by a 5'-3' exonuclease suggests a mechanism for the release of the U7 snRNP after processing by shortening the cut-off histone spacer sequences base paired to U7 RNA.

Mats of psychrophilic thiotrophic bacteria associated with cold seeps of the Barents Sea

This study focused on the bacterial diversity associated with microbial mats of deep-sea cold seeps at the Norwegian continental margin. Study sites included the Storegga and Nyegga areas as well as the Håkon Mosby mud volcano, where the mats occurred at temperatures permanently close to the freezing point of seawater. Two visually different mat types, i.e. small gray mats and extensive white mats, were studied with the aim to determine the identity of the mat-forming sulfide oxidizers, and to investigate which environmental factors (e.g. sulfate reduction and methane oxidation rates) shown here could explain the observed diversity. Sequence data have been submitted to the EMBL database under accession No. FR847864-FR847887 (giant sulfur bacteria), No. FR827864 (Menez Gwen filament; see Supplementary Material) and No. FR875365-FR877509 (except FR875905; remaining partial sequences).

Niche differentiation among mat-forming, sulfide-oxidizing bacteria in chemosynthetic ecosystems of the Nile Deep Sea Fan (Eastern Mediterranean Sea)

Sulfidic muds of cold seeps on the Nile Deep Sea Fan are populated by different types of mat-forming sulfide-oxidizing bacteria. The predominant sulfide oxidizers of three different mats were identified by microscopic and phylogenetic analyses as (i) Arcobacter species producing cotton-ball-like sulfur precipitates, (ii) large filamentous sulfur bacteria including Beggiatoa species, or (iii) single, spherical cells resembling Thiomargarita species. High resolution in situ microprofiles revealed different geochemical settings selecting for different mat types. Arcobacter mats occurred where oxygen and sulfide overlapped at the bottom water interface. Filamentous sulfide oxidizers were associated with non-overlapping, steep gradients of oxygen and sulfide. A dense population of Thiomargarita was favored by temporarily changing supplies of oxygen and sulfide. These results indicate that the decisive factors in selecting for different mat-forming bacteria within one deep-sea province are spatial or temporal variations in energy supply. Furthermore, the occurrence of Arcobacter spp.-related 16S rRNA genes in the sediments below all three types of mats, as well as on top of brine lakes of the Nile Deep Sea Fan, indicates that this group of sulfide oxidizers can switch between different life modes depending on the geobiochemical habitat setting.

Biomass and substrate utilization of cold adapted bacteria in Fram Strait and the Western Greenlad Sea

During the 'Polarstern' expedition ARK-IV/2 in June 1987, water samples from 8 stations were taken to study biomass and substrate utilization of cold adapted bacteria. Bacterial biomasses determined from acridine orange direct counts (AODC) were between 0.4 and 31.4 µ/g C/l, and ATP concentrations amounted from <0.1 to 40 ng/l. Colony counts on seawater agar reached only 0.1% of AODC, but with the MPN-method 1 to 10% of AODC were recorded. With 14C-glutamic acid or 14C-glucose as tracer substrate in oligotrophic broth containing 0.5 mg trypticase and 0.05 mg yeast extract per liter of seawater, obligately oligotrophic bacteria could be detected in one water sample. Although incubation was at 2 °C, only psychrotrophic bacteria showing growth temperatures between 1 and 30 °C were obtained. Organic substrate utilizations by 106 isolates were tested at 4 and 20 °C. Most carbohydrates, organic acids, alcohols, and alanine were assimilated at both temperatures, but arginine, aspartate and ornithine were utilized only at 20 °C by almost all strains.

Rates of nitrogen cycling and chemo-autotrophy in the cold-water coral Lophelia pertusa

Cold-water corals (CWC) are widely distributed around the world forming extensive reefs at par with tropical coral reefs. They are hotspots of biodiversity and organic matter processing in the world's deep oceans. Living in the dark they lack photosynthetic symbionts and are therefore considered to depend entirely on the limited flux of organic resources from the surface ocean. While symbiotic relations in tropical corals are known to be key to their survival in oligotrophic conditions, the full metabolic capacity of CWC has yet to be revealed. Here we report isotope tracer evidence for efficient nitrogen recycling, including nitrogen assimilation, regeneration, nitrification and denitrification. Moreover, we also discovered chemoautotrophy and nitrogen fixation in CWC and transfer of fixed nitrogen and inorganic carbon into bulk coral tissue and tissue compounds (fatty acids and amino acids). This unrecognized yet versatile metabolic machinery of CWC conserves precious limiting resources and provides access to new nitrogen and organic carbon resources that may be essential for CWC to survive in the resource-depleted dark ocean.

Radiocarbon dating on cold-water corals and planktonic foraminifera, grain size analysis, stable oxygen isotopes, and XRF data of sediment cores from the Alboran Sea

Cold-water corals are common along the Moroccan continental margin off Melilla in the Alboran Sea (western Mediterranean Sea), where they colonise and largely cover mound and ridge structures. Radiocarbon ages of the reef-forming coral species Lophelia pertusa and Madrepora oculata sampled from those structures, reveal that they were prolific in this area during the last glacial-interglacial transition with pronounced growth periods covering the Bølling-Allerød interstadial (13.5-12.8 ka BP) and the Early Holocene (11.3-9.8 ka BP). Their proliferation during these periods is expressed in vertical accumulation rates for an individual coral ridge of 266-419 cm ka**-1 that consists of coral fragments embedded in a hemipelagic sediment matrix. Following a period of coral absence, as noted in the records, cold-water corals re-colonised the area during the Mid-Holocene (5.4 ka BP) and underwater photographs indicate that corals currently thrive there. It appears that periods of sustained cold-water coral growth in the Melilla Coral Province were closely linked to phases of high marine productivity. The increased productivity was related to the deglacial formation of the most recent organic rich layer in the western Mediterranean Sea and to the development of modern circulation patterns in the Alboran Sea.