Aligned pipe arrays formation by silicon anodic etching

A simple technique is described here that produces aligned curved or straight arrays of pipes. This opens the way to produce complete systems (electronic, photonic and fiber optic connectors) from silicon with large scale fabrication techniques. Our strategy in creating parallel pipes is to use high current densities (similar to 100 mA/cm(2)) silicon anodization in HF solutions, in a cell where the current direction and the preferential etching directions are not coincident in (111) silicon substrates. The etched structure in a nanoscale range was observed using atomic force microscopy, which shows steps. In a macroscopic scale steps were observed in the walls of arrays of tenths of millimeters diameter pipes. Pores arrays were obtained forming a similar to 90 degrees angle with the current direction. Molecular mechanics simulations of the pipe wall structure show that a preferential etching along the direction and passivation of the (111) planes are the mechanisms responsible for the formation of pore arrays structure. (C) 1998 American Vacuum Society.1642105210

Nitrogen substitution of carbon in graphite: Structure evolution toward molecular forms

A series of randomly nitrogen-substituted carbon clusters in graphitelike structures, containing up to 96 carbon atoms, is theoretically investigated through semiemipirical pseudopotential techniques. The evolution of conformation and electronic structure is obtained as a function of nitrogen content. Results from semiempirical geometry optimizations reveal that the clusters are planar for nitrogen concentrations up to [N]/[C]similar to 20%. Above this concentration, buckling develops in the clusters. One of the characteristics of these corrugated clusters is the presence of carbon dangling bonds. Chemical stabilization imposes that these structures evolve to either a three-dimensional, fully covalent carbon nitride network, or to molecular forms. Among the well-defined molecular structures that could develop in amorphous carbon nitride, we found nanotubules and a molecular cage of elemental compositions CN and C3N4, respectively. [S0163-1829(38)06943-4].5820139181392

The users centered design of a new digital fluorometer

The fluorometer is the equipment used in chemical analysis laboratories, research institutes and nuclear fuel cycle companies. This equipment measures an unknown amount of uranium in ores, rivers, etc. The fluorometer functioning is based on the uranium fluorescence when submitted to the ultraviolet radiation incidence. The fluorescence is measured by an electronic optic system with optics filters, photomultiplier tube, and a current amplifier. The user centered design involvers the user in the product development in all phases of the design process. Users are not simply consulted at the beginning of the design process and evaluated the system at the end; they are treated as partners throughout the design process. The user centered design emphasizes the needs and abilities of the users and improves the usability of the equipment. The activity centered design emphasizes the development of the equipment with a deep understanding of the users activities and of the current work practices of the users. The aim of this paper is to present a methodological framework that contributes to the design and evaluation of a new digital fluorometer towards an approach related to the users and their activities. This methodological framework includes users-based testing, interviews, questionnaires, human factors standards and guidelines, the users activity analysis and users satisfaction questionnaire

Electronic structure of nitrogen-carbon alloys (a-CNx) determined by photoelectron spectroscopy

The electronic structure of nitrogen-containing diamondlike films prepared by sputtering was determined by photoelectron spectroscopy. The N 1s core-level spectra are constituted by two peaks at 400.5 and 398.2 eV associated with substitutional N sp(2) in aromatic rings and N bonded to C sp(3), respectively. On increasing N, the top of the valence band suffers profound changes. The new features are identified by a comparison of the experimental spectra with theoretically calculated density of states of nitrogen-containing graphite and C3N4 structures. [S0163-1829(98)04004-1].5742536254

Vibrational analysis of amorphous carbon-nitrogen alloys by N-15 and D isotopic substitution

The origin of the vibrational modes of a-CN, alloys is investigated by infrared (ir) and Raman spectroscopies. Isotopic substitution of N-15 and D is used in the identification of vibration modes. In nonhydrogenated materials containing low nitrogen concentration (less than or equal to 20 at. %), the ir and Raman spectra are not equivalent. Above this concentration (up to similar to 30 at.%), the spectra became very similar to each other. On the contrary, for a suitable hydrogen content the spectra are quite similar, independently of the range of nitrogen concentrations studied. Quantum chemical Parametric Method 3 calculations are performed to obtain the frequencies and intensities of the ir active vibrations of organic molecules and large carbon-nitrogen clusters. These results are used to help in the identification of the features observed in the ir spectra. The importance of both the promotion of bond dipoles and symmetry breaking by nitrogen in the ir spectra is established.6121083108

Soft situational strategic planning (SSSP): a method and case study of its application in a Brazilian municipality

Municipal government planning is challenging in the extreme being characterised by ill-structured and messy problems, the complexity of which is compounded by often conflicting views and priorities of multiple stakeholders. In South America, Situational Strategic Planning (SSP) is a wide spread method of such planning. The purpose of this paper is to explore the use of a proposed multi-methodological approach, Soft Situational Strategic Planning (SSSP) in a South American municipal government. SSSP is a variant of SSP enhanced with elements of Soft Systems Methodology (SSM) and Strategic Choice Approach (SCA). Through an action research case study in a Brazilian municipality, we implemented SSSP through a strategic planning cycle. The findings suggest that SSSP complement the SSP process regarding the implementation and monitoring of strategy. The application also indicated that SSSP has the potential to make government planning processes more structured for policy makers

Fimose e Circuncisão

A circuncisão é um procedimento cirúrgico muito frequente, por vezes com indicações clínicas pouco esclarecidas. Apesar de um método simples, tem riscos e complicações, pelo que deve ser bem ponderada a necessidade da sua realização, sobretudo em crianças e recém-nascidos. Torna-se necessário saber distinguir entre fimose fisiológica e fimose patológica. Nesta revisão pretende-se abordar as indicações cirúrgicas da circuncisão, as suas técnicas de execução e os diversos tratamentos alternativos

High prevalence of malnutrition and nutrition impact symptoms in older patients with cancer:Results of a Brazilian multicenter study

Background Malnutrition in cancer is an independent factor associated with negative clinical outcomes. The objective of this study was to evaluate the prevalence of malnutrition across different age groups in patients with cancer in Brazil and to identify associations with nutrition impact symptoms (NIS). Methods In this observational, cross-sectional, multicenter study, the authors evaluated 4783 patients with cancer aged >= 20 years who were admitted to 45 public hospitals in Brazil. Nutritional status, nutritional risk, and NIS were evaluated using the Patient-Generated Subjective Global Assessment. Results More than one-fourth (25.5%) of all participants were aged >= 65 years. In patients aged >= 65 years, the prevalence of moderate/suspected and severe malnutrition was 55%, it was 45.4% in those aged 51 to 64 years, and it was 36.1% in those aged = 65 years were no appetite (odds ratio [OR], 1.90; 95% CI, 1.62-2.22; P 50 years than in those age

Pressure-induced physical changes of noble gases implanted in highly stressed amorphous carbon films

Noble gases (Ar, Kr, and Xe) were trapped in an amorphous carbon matrix in the 1-11-GPa pressure range. Extended and near-edge x-ray-absorption spectroscopies indicate clustering of noble gases induced by the host matrix internal pressure. Simultaneously, the matrix pressure promotes a shift of the noble-gas core-level binding energy of similar to1 eV. The Auger parameter reveals that both the initial state and the host relaxation terms contribute to the binding-energy shift. Ab initio calculations performed on an Ar-7 cluster and on Ar atoms clustered in aromatic molecules support the experimental findings.68

Green genes: bioinformatics and systems-biology innovations drive algal biotechnology.

Many species of microalgae produce hydrocarbons, polysaccharides, and other valuable products in significant amounts. However, large-scale production of algal products is not yet competitive against non-renewable alternatives from fossil fuel. Metabolic engineering approaches will help to improve productivity, but the exact metabolic pathways and the identities of the majority of the genes involved remain unknown. Recent advances in bioinformatics and systems-biology modeling coupled with increasing numbers of algal genome-sequencing projects are providing the means to address this. A multidisciplinary integration of methods will provide synergy for a systems-level understanding of microalgae, and thereby accelerate the improvement of industrially valuable strains. In this review we highlight recent advances and challenges to microalgal research and discuss future potential.We acknowledge support from the EU FP7 project SPLASH (Sustainable PoLymers from Algae Sugars and Hydrocarbons), grant agreement number 311956.This is the accepted manuscript. The final version is available from Cell/Elsevier at http://www.sciencedirect.com/science/article/pii/S016777991400196