A systematic procedure to enhance reproducibility of SWASV cycles in the determination of toxic metals in real samples

This work presents for the first time a systematic study on the optimization of the electrochemical cleaning time of a mercury film when it is used as a working electrode material in the analysis of toxic metals, such as Pb2+, used as model metal, in real samples by SWASV. The optimization study for the film’s cleaning time aimed at attaining a Pb2+ minimum value in the film after the re-oxidation step of the pre-concentrated metal, given the impossibility of complete removal of traces of the electroactive species from the film. This value was kept constant in each concentration range studied ensuring thus that all assays were performed in initial identical conditions. An assay performed on a synthetic sample was taken as reference. In it, given the absence of matrix effects, and after the electrochemical cleaning step, a direct proportionality was observed between the residual amounts of Pb2+ in the film (which for the cleaning time used was never completely removed) and Pb2+ concentration in the solution. This fact determined a high correlation between Pb2+ peak current and Pb2+ concentration which was not observed when real samples (tree leaves) were analyzed. This behavior may result from the presence of the interfering surfactants always present in real samples of complex matrix. Cleaning time optimization was performed for the following Pb2+ concentration ranges in the real samples of complex matrix: 0.006-0.020, 0.020-0.080, 0.060-0.200 and 0.100-0.600 ppb. As expected, in order to obtain identical levels of film’s cleaning efficiency, the need for longer cleaning times has been observed for higher concentrations. The optimized cleaning times for the concentration ranges under study were 120, 150, 180 e 300 s, respectively

Sealing Capability and SEM Observation of the Implant-Abutment Interface

To evaluate the sealing capability of external hexagon implant systems and assess the marginal fit, two groups (n = 10 each) were employed: SIN (Sistema de Implantes Nacional, Brazil) and Osseotite, (Biomet 3i, USA). Sealing capability was determined by placing 0.7 μL of 1% acid-red solution in the implant wells before the torque of their respective abutments. Specimens were then placed into 2.5 mL vials filled with 1.3 mL of distilled water with the implant-abutment interface submerged. Three samples of 100 μL water were collected at previously determinate times. The absorbance was measured with a spectrophotometer, and the data were analyzed by Two-way ANOVA (P < .05) and Tukey's test. Marginal fit was determined using SEM. Leakage was observed for both groups at all times and was significantly higher at 144 hrs. SEM analysis depicted gaps in the implant-abutment interface of both groups. Gaps in the implant-abutment interface were observed along with leakage increased at the 144 hrs evaluation period

Por uma nova cultura da água no ensino básico

A presente comunicação centra-se na apresentação à comunidade científica de um Projecto de investigação em Educação que tem como finalidade produzir contributos para o Ensino Básico, no âmbito do que se designa como uma Nova Cultura da Água. Com esta iniciativa pretendemos não só alertar para a pertinência e importância de estudos em ordem a uma temática cada vez mais emergente, mas também recolher contributos significativos de uma comunidade mais alargada. O referido projecto centra-se pois no bem Água. Começará por procurar conhecer melhor como ele é evocado e tratado no Ensino Básico. Destina-se a aprofundar e promover teorias, conhecimentos, competências, valores, atitudes e práticas que potenciem o bom uso e a protecção daquele bem, e de um modo mais geral uma alteração de posturas culturais e mesmo civilizacionais. Fá-lo-á segundo perspectivas científicas, pedagógicas, didácticas e sociais em parte já construídas e em parte a construir, e que justificadamente se considerem adequadas. O Projecto assume estar à partida marcado por saberes, perspectivas, ideais, dilemas e objectivos dos elementos da equipa do Projecto e por outras visões que, globalmente e de um modo aproximativo, aglomeramos sob a designação Nova Cultura da Água. Simultaneamente, assume que pretende contribuir para que tal Nova Cultura da Água seja mais bem compreendida e especificada, e em particular para que ela seja mais enriquecida com contributos portugueses. O âmbito central de intervenção do Projecto é o Ensino Básico, mas desde logo isso implica a sua intersecção com a Formação (Inicial e Contínua) de Professores, e portanto com o Ensino Superior. Além disso, pela natureza do tema, do bem, em estudo, o Projecto intersecta-se também com os mundos das Ciências e das Tecnologias. Intersecta-se também com a Sociedade em geral, e designadamente com a formação para a cidadania de cidadão portugueses que são também cidadãos da Península Ibérica, da Europa e do Mundo. O Projecto terá pois múltiplas incidências e mesmo, previsivelmente, contributos de vários tipos e âmbitos, designadamente a nível de divulgação científica e a um nível pedagógico geral. Mas é essencialmente um Projecto do âmbito da Didáctica. Tem a sua focagem na Escola, portanto em ambientes de ensino e aprendizagem formais, e incide sobre meios e métodos relacionados com ambientes de aula (em sentido lato)

Método para determinação de umidade de plantas aromáticas.

Materias necessários; Reagentes; Equipamentos e vidrarias; Protocolo do método de determinação de umidade; Destilação da amostra; Obtenção do destilado; Determinação do teor de umidade.bitstream/CNPAT-2010/11962/1/cotb-136.pd

Generation and Distribution of Quantum Oblivious Keys for Secure Multiparty Computation

The oblivious transfer primitive is sufficient to implement secure multiparty computation. However, secure multiparty computation based only on classical cryptography is severely limited by the security and efficiency of the oblivious transfer implementation. We present a method to efficiently and securely generate and distribute oblivious keys by exchanging qubits and by performing commitments using classical hash functions. With the presented hybrid approach, quantum and classical, we obtain a practical and high-speed oblivious transfer protocol, secure even against quantum computer attacks. The oblivious distributed keys allow implementing a fast and secure oblivious transfer protocol, which can pave the way for the widespread of applications based on secure multiparty computation.Comment: 11 pages, 5 figure

First lunar outpost

Design and research efforts at the University of Puerto Rico have focused on the evaluation and refinement of the Habitability Criteria for a prolonged human presence in space during the last four years. Living quarters for a Mars mission and a third generation lunar base concept were proposed. This academic year, 1991-92, work on further refinement of the habitability criteria and design of partial gravity furniture was carried on. During the first semester, design alternatives for furniture necessary in a habitat design optimized for lunar and Martian environments were developed. Designs are based on recent research data from lunar and Mars gravity simulations, and current NASA standards. Artifacts will be submitted to NASA architects to be tested in KC-135 flights. Test findings will be submitted for incorporation in future updates to NASA habitat design standards. Second semester work was aimed at integrating these findings into the First Lunar Outpost (FLO), a mission scenario currently being considered by NASA. The mission consists of a manned return to the moon by crews of four astronauts for periods of 45 days. The major hardware components of the mission are as follows: (1) a Crew Module for the delivery of the crew and their supplies, and (2) the Habitat Module, which will arrive on the Moon unmanned. Our design efforts concentrated on this Habitat Module and on application of habitability criteria. Different geometries for the pressure vessel and their impact on the interior architecture were studied. Upon the selection of a geometry, a more detailed analysis of the interior design was performed, taking into consideration the reduced gravity, and the protection against radiation, micrometeorites, and the extreme temperature variation. A proposal for a FLO was submitted by the students, consisting essentially of a 24-feet (7.3 m.) by 35-feet (10.67 m) high vertical cylinder with work areas, crew quarters, galley, wardroom, leisure facilities, health maintenance, waste management, EVA operations facilities, and safe havens

ITC's strategic plan for Open Science 2021-2025:towards an open future

Open Science (OS) is an umbrella term comprising principles to increase the transparency of research. Besides Open Access to scientific articles, these principles contain public availability of reusable methods (e.g., code and tools), data, and educational materials. This document outlines a plan to achieve the transition towards OS. ITC’s Strategic Plan for OS 2021-2025 - Towards an Open Future contains five initiatives: 1.OS at ITC aims to provide guidelines and OS capacity development to address the obstacles ITC researchers encounter when doing OS. 2.The ITC Knowledge Hub will provide services and tools to access, create, and publish open research, including scientific results based on qualitative/quantitative analyses using computational workflows. 3.Open Educational Resources will be addressed by exploring options to realise Open Educational Resources at ITC and providing lecturers with guidelines and support to create them. 4.The OS Community Twente serves as an inter-disciplinary, bottom-up community to promote, learn, share, and discuss OS practices. 5.Research & Funding aims to address challenges in OS through innovative developments and user studies. A further output is to generate funding to realise the ambitious aims presented in the plan. For a successful OS transition, the initiatives aim to address the Rewards & Recognition system, valorise Sharing & Collaboration, develop OS Knowledge & Skills, and foster Cultural change & Societal impact