Microscopic mechanism for mechanical polishing of diamond (110) surfaces

Mechanically induced degradation of diamond, as occurs during polishing, is studied using total--energy pseudopotential calculations. The strong asymmetry in the rate of polishing between different directions on the diamond (110) surface is explained in terms of an atomistic mechanism for nano--groove formation. The post--polishing surface morphology and the nature of the polishing residue predicted by this mechanism are consistent with experimental evidence.Comment: 4 pages, 5 figure

Loop Quantization of the Supersymmetric Two-Dimensional BF Model

In this paper we consider the quantization of the 2d BF model coupled to topological matter. Guided by the rigid supersymmetry this system can be viewed as a super-BF model, where the field content is expressed in terms of superfields. A canonical analysis is done and the constraints are then implemented at the quantum level in order to construct the Hilbert space of the theory under the perspective of Loop Quantum Gravity methods.Comment: 17 pages, Late

The filamentous fungi culture collection of the Department of Food Science (CCDCA), Federal University of Lavras, Brazil

Brazil has one of the highest levels of biological diversity due to its large geographical area, high coverage by rainforests, and endemic biomes, such as the Brazilian Atlantic Forest, Cerrado and Caatinga. Of the estimated 1.5 million species of fungi only 5% are known. Much of this unknown biodiversity is in the tropics, which is seriously threatened by some agricultural activities, reinforcing the urgent need for biodiversity studies in these areas. The maintenance and preservation of fungal cultures are important elements for such a requirment. The establishment of a culture collection of filamentous fungi in the Mycotoxins and Mycology Laboratory, Department of Food Science (CCDCA), Federal University of Lavras (UFLA) commenced from the bases of species maintenance, taxonomy, biotechnology and toxigenicity. The laboratory was established in 2007 to preserve potentially mycotoxigenic fungi, especially ochratoxin A and aflatoxins producers, which were isolated from food. Currently the CCDCA has more than 1000 isolates of Aspergillus, Penicillium, Cladosporium, Fusarium, Alternaria, Chaetomium, Mucor, Eurotium, and Neosartorya. A total of 66 species are represented which were isolated from food, cave environments, and soils of the Brazilian Atlantic Forest, Cerrado and Caatinga. A total of 328 cultures are preserved and maintained by periodic subculture, 137 by mineral oil preservation, and 550 by filter paper preservation. The staff trains graduate students in the taxonomy of major taxa of importance to agricultural research and food science. Finally, the CCDCA and UFLA, Brazil, in collaboration with the IBB-Biological Engineering Centre, Micoteca da Universidade do Minho, Portugal, intend to develop a project on polyphasic studies of Aspergillus and Penicillium isolated from various substrates, sources, and environments in Brazil. To pursue this aim CCDCA intends to: a) preserve Aspergillus and Penicillium strains for comparative studies between Brazilian regions and worldwide; b) foster the study of Aspergillus and Penicillium for biotechnological and toxigenic potential, and training in identification, preservation and distribution; c) establish quality control of fungal assays; and d) establish the CCDCA as a member of the global network of culture collections and participate in the international forums and organisations related to culture collections

Uso de marcadores fenotípicos e bioquímicos para caracterização de isolados de Aspergillus seção Flavi

Os fungos do gênero Aspergillus seção Flavi representam uma das seções mais importantes do gênero e apresentam elevada variabilidade morfológica e bioquímica. Com o advento da abordagem polifásica, sua taxonomia tem sido constantemente revisada. O presente trabalho teve como objetivo utilizar diferentes metodologias para verificar o poder discriminatório dos métodos morfológico, bioquímico, molecular e de espectrometria de massas de isolados de Aspergillus seção Flavi. Trinta e um isolados foram analisados pelos métodos macro e micromorfológicos, potencial micotoxigênico, sequências parciais do gene da calmodulina e espectros de massas pela técnica de MALDI-TOF MS. Os dendrogramas foram gerados e os resultados foram comparados. Foi possível identificar pelo método morfológico 100% dos isolados dos quais 90,6% foram produtores de micotoxinas. Os resultados do MALDI-TOF MS apresentaram elevado poder discriminatório. Contudo, através da base de dados utilizada (SARAMISTM), não foi possível a identificação de todos os isolados por MALDI-TOF MS. Os dados da biologia molecular confirmaram todos os resultados obtidos pela caracterização morfológica. A integração dos diferentes métodos de identificação fúngica é fundamental para obter uma caracterização taxonômica eficiente, conduzindo a uma utilização segura desses fungos em processos biotecnológicos.Fabiana Couto agradece à CAPES (Brasil), pela concessão da bolsa do PDSE- Proc.8161-12-7

Instruções práticas para produção de composto orgânico em pequenas propriedades.

bitstream/CNPH-2009/34479/1/cot_53.pd