Curvature driven phase separation in mixed ligand coated gold nanoparticles

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.Includes bibliographical references (leaves 31-33).Monolayer-coated gold nanoparticles have been the subject of extensive studies in fields ranging from physics to medicine. The properties of these nanomaterials such as solubility and surface energy are often attributed solely to the chemical functionalities of the ligand head-groups. However, the morphology of these monomolecular layers on gold nanoparticles plays as important of a role as the surface chemistry. Intriguing phase-separation phenomena have been observed for mixed self-assembled monolayers (SAM) of octanethiol (OT) and mercaptopropionic acid (MPA) on the surface of gold nanoparticles. These ordered structures are studied here through scanning tunneling microscope (STM) images, as a function of the gold core diameter, which is a measure of the particle's curvature. The packing of OT homoligand nanoparticles is found to have a head-group spacing of 0.54 nm, which differs from that on flat gold (111) surfaces, 0.5 nm. The OT:MPA heteroligand nanoparticles are observed to phase-separate into ordered ribbon-like domains, with spacings that depend on the nanoparticle diameter. A geometric framework that includes a continuous and crystallographic description is established to best describe the observed behaviors.by Paulo H. Jacob Silva.S.B

Erosion of rocky shores- protection promoted by sandy beaches and shore platforms

O sector costeiro do Algarve central entre as praias da Galé e Olhos de Água deve a sua fisiografia crenulada a um sistema cársico bem desenvolvido em rochas carbonatadas. As arribas possuem no sopé uma plataforma litoral rochosa ou uma praia arenosa. Os principais objectivos do projecto de investigação EROS são: (i) a quantificação da dissipação da energia das ondas ao longo de plataformas litorais e de praias arenosas com diferentes declives e exposição às ondas; (ii) a caracterização da refracção e difracção das ondas e da modificação das correntes forçadas pelo controle morfológico. A metodologia base centra-se na aquisição de dados de ondas e correntes utilizando transdutores de pressão e correntómetros colocados em transeptos normais à linha de costa, de modo a obter o espectro completo de ondas e correntes, desde a água profunda até aproximadamente à base das arribas, quer nas plataformas quer nas praias.FCT- Research Project PTDC/CTE-GIX/11123

JUSTIÇA COMO EQUIDADE E A FUNDAMENTAÇÃO DE POLÍTICAS DISTRIBUTIVAS SOCIOCULTURAIS

RESUMO:A justiça como equidade desenvolvida por John Rawls é uma das mais importantes teorias da filosofia política e, em razão desta enorme influência, é recorrentemente utilizada para fundamentar políticas estatais distributivas. O presente estudo se propõe a investigar se a teoria rawlsiana exposta em Uma teoria de Justiçafornece fundamentação explícita e suficiente às políticas voltadas às demandas redistributivas decorrentes das desigualdades socioculturais. Palavras-chave:Justiça como equidade. Políticas distributivas. Desigualdades socioculturais

Peptide-Grafted Nontoxic Cyclodextrins and Nanoparticles against Bacteriophage Infections

One of the biggest threats for bacteria-based bioreactors in the biotechnology industry is infections caused by bacterial viruses called bacteriophages. More than 70% of companies admitted to encountering this problem. Despite phage infections being such a dangerous and widespread risk, to date, there are no effective methods to avoid them. Here we present a peptide-grafted compounds that irreversibly deactivate bacteriophages and remain safe for bacteria and mammalian cells. The active compounds consist of a core (cyclodextrin or gold nanoparticle) coated with a hydrophobic chain terminated with a peptide selective for bacteriophages. Such peptides were selected via a phage display technique. This approach enables irreversible deactivation of the wide range of T-like phages (including the most dangerous in phage infections, phage T1) at 37 degrees C in 1 h. We show that our compounds can be used directly inside the environment of the bioreactor, but they are also a safe additive to stocks of antibiotics and expression inducers (such as isopropyl beta-D-1-thiogalactopyranoside, i.e., IPTG) that cannot be autoclaved and are a common source of phage infections

Ecological Apparency Hypothesis and Availability of Useful Plants: Testing different seu values

The present study tested the ecological apparency hypothesis in a Brazilian rural community. It used the use value to test the information gained through three types of calculations (UVchange, UVgeneral, UVpotential). A vegetation inventory was performed in two areas near Capivara, Paraíba, Brazil, and 112 informants were interviewed. For the hypothesis test, the Spearman correlation coefficient was used to correlate the phytosociological (vegetation) and ethnobotanical data (use value). The study recorded 25 useful species in the first site and 20 in the second site. Positive correlations were found in the first site, between the UVg to basal area and dominance, and between the UVc and basal area, dominance, and importance value. In the second site, between the UVg and both basal area and dominance and between UVc and basal area, density, and dominance. Apparency explained the local importance of useful plants in construction, technology, and fuel, but was not explanative of medicine. Also, important responses were observed for the different use values

Sustainability-focused international PBL project:Rethinking digital education for individuals of low socioeconomic status

Providing access to education for individuals of lower socio-economic status is a significant way to reduce poverty, as it empowers them to grow as professionals and as individuals. Although there is an increasing sense of urgency to promote these changes, notably motivated by the Sustainable Development Goals (SDGs) set by the UN 2030 Agenda, there are still few successful ways to solve this problem on a large-scale. As digital technology develops and affordability increases, new ways to share quality educational content are created. In an exploratory case study, with a qualitative approach, this paper presents the development of a digital application focused on providing quality educational content directed to vulnerable groups that lack access to formal learning experiences, specifically focused on waste pickers in Brasilia, Brazil. The main data collection methods used to make the decisions through the development process were observation, surveys, and interviews. Within the framework of Problem Based Learning (PBL) an international cross-disciplinary collaboration among different universities, the project, denominated “Mobile Education”, involved: (i) the design and implementation of a system consisting of both a web and mobile application; (ii) the research of a viable business model to provide long-term sustainability for the project; (iii) and the creation of a pilot course of financial education for the preliminary target group, i.e., waste pickers from Brasilia, Brazil. Conclusively, the project aims to positively impact social transformation for individuals who work at the Waste Sorting facilities and lack financial knowledge. The Mobile Education project resulted in a functional version of the app (Web and Mobile) as well as the delimitation of a viable business model to keep it providing digital equality in Brazilian education

Challenges to balance food demand and supply: analysis of PNAE execution in one semiarid region of Brazil

This study intended to address the challenges faced by the National School Feeding Program (PNAE) to implement public purchases from family farming, as they understand their role in the transformation of local food systems. For this, we developed a qualitative, exploratory, and descriptive study, in the state of Rio Grande do Norte, located in the northeastern semiarid region, during the regional assessments done by the Collaborating Center for the School Feeding Program in 2018 and 2019. We analyzed the policy from the perspective of the social actors inserted at the ends of the supply and demand chain through the application of questionnaires and focus groups. There were 188 social actors from 45 municipalities taking part in our data gathering. We examined the meeting of supply and demand based on the performance of the policy in the state, and identified that: i) the percentage of purchases between 2011 and 2017 was, on average, 19.1%, demonstrating that, despite not meeting the recommended rate, the state has progressed its investments in this segment; ii) some limitations characterized the limited effectiveness of public purchases of family farming for schools: lack of federal actions to enhance the value of family farming, unfavorable conditions for local agricultural production, low performance of technical rural assistance, menus do not reflect the offer of family farming, difficulties in preparing and executing the public call and insufficient communication between social actors; iii) Action and decision-making, through street-level bureaucracy, depends on the discretion of the social actors. We believe that this study can collaborate in the understanding of structural problems that affect the implementation of the program and assist in the search for alternatives that are consistent with the current needs, aiming at the construction of sustainable food systems.This study intended to address the challenges faced by the National School Feeding Program (PNAE) to implement public purchases from family farming, as they understand their role in the transformation of local food systems. For this, we developed a qualitative, exploratory, and descriptive study, in the state of Rio Grande do Norte, located in the northeastern semiarid region, during the regional assessments done by the Collaborating Center for the School Feeding Program in 2018 and 2019. We analyzed the policy from the perspective of the social actors inserted at the ends of the supply and demand chain through the application of questionnaires and focus groups. There were 188 social actors from 45 municipalities taking part in our data gathering. We examined the meeting of supply and demand based on the performance of the policy in the state, and identified that: i) the percentage of purchases between 2011 and 2017 was, on average, 19.1%, demonstrating that, despite not meeting the recommended rate, the state has progressed its investments in this segment; ii) some limitations characterized the limited effectiveness of public purchases of family farming for schools: lack of federal actions to enhance the value of family farming, unfavorable conditions for local agricultural production, low performance of technical rural assistance, menus do not reflect the offer of family farming, difficulties in preparing and executing the public call and insufficient communication between social actors; iii) Action and decision-making, through street-level bureaucracy, depends on the discretion of the social actors. We believe that this study can collaborate in the understanding of structural problems that affect the implementation of the program and assist in the search for alternatives that are consistent with the current needs, aiming at the construction of sustainable food systems

Synthesis of beta-phenylchalcogeno-alpha, beta-unsaturated esters, ketones and nitriles using microwave and solvent-free conditions

A simple, clean and efficient solvent-free protocol was developed for hydrochalcogenation of alkynes containing a Michael acceptor (ester, ketone and nitrile) with phenylchalcogenolate anions generated in situ from the respective diphenyl dichalcogenide (Se, Te, S), using alumina supported sodium borohydride. This efficient and improved method is general and furnishes the respective (Z)-beta-phenylchalcogeno-<FONT FACE=Symbol>a,b</FONT>-unsaturated esters, ketones and nitriles, in good yield and higher selectivity, compared with those that use organic solvent and inert atmosphere. The use of microwave (MW) irradiation facilitates the procedure and accelerates the reaction