Mid-infrared Gas Sensing Using Graphene Plasmons Tuned by Reversible Chemical Doping

Highly confined plasmon modes in nanostructured graphene can be used to detect tiny quantities of biological and gas molecules. In biosensing, a specific biomarker can be concentrated close to graphene, where the optical field is enhanced, by using an ad-hoc functional layer (e.g., antibodies). Inspired by this approach, in this paper we exploit the chemical and gas adsorption properties of an ultrathin polymer layer deposited on a nanostructured graphene surface to demonstrate a new gas sensing scheme. A proof-of-concept experiment using polyethylenimine (PEI) that is chemically reactive to CO2 molecules is presented. Upon CO2 adsorption, the sensor optical response changes because of PEI vibrational modes enhancement and shift in plasmon resonance, the latter related to polymer-induced doping of graphene. We show that the change in optical response is reversed during CO2 desorption. The demonstrated limit of detection (LOD) of 390 ppm corresponds to the lowest value detectable in ambient atmosphere, which can be lowered by operating in vacuum. By using specific adsorption polymers, the proposed sensing scheme can be easily extended to other relevant gases, for example, volatile organic compounds.Peer ReviewedPostprint (published version

GÊNESE, MODERNIZAÇÃO E REESTRUTURAÇÃO DO COMPLEXO AGROINDUSTRIAL LÃCTEO BRASILEIRO

During the period between 1945 and 1991 the dairy sector was regulated by the State. The price standardization imposed by the government, conducted many times aiming to facilitate adjustments in economy, had serious consequences right after the end of said intervention. The present study tried to understand the process which outlined the conformation of the current institutional structure in this complex, the causes of its maintenance, and the immediate trends which may be envisaged in short and medium terms. There is an absence of public policies devised to account for the incoherences detected in the dairy complex which originate to a large extent in the deliberate loss of the power of regulation by the State and in the liberal orientation taken in the end of the 80s. With the end of the State regulation new mechanisms of support and financing emerged, but those do not go directly under the State actors appreciation. However, the dynamics of the productive restructuring is not yet over. A new phase may be replacing the former, and the actors in the dairy agri-food complex once again should look for solutions for the situations which generate uncertainty and changes, originated in the search for higher competitiveness and professionalization since those proved vital for the permanence of such actors in the formal productive activity.sectorial policies, agri-industry, milk, industrial organization., Agribusiness, Livestock Production/Industries,

CONTRIBUIÇÃO DA CERTIFICAÇÃO ORGÂNICA PARA UM NOVO MODELO DE GOVERNANÇA NO COMPLEXO AGROINDUSTRIAL CITRÃCOLA BRASILEIRO

This paper compares governance structures in the Brazilian citrus production that appeared with the process of international certification of organic products. Both governance structures, between organic orange production and the processing plant, are analyzed through a study case methodology. These two governance structures are different from the traditional dominant structures that were consolidated with the industrial oligopoly of frozen and concentrated orange juice production along the last thirty years in Brazil. The analyzed cases (onward integration and onward partial-integration) can be used as a reference for possible penetrations of alternative organizational forms in citrus production in an agro-industrial complex predominantly directed at commodity exportation (frozen concentrated orange juice) that has been excluding thousands of citrus producers since 1990. The theoretical basis of this work is the new institutional economy (NIE), known as transaction cost approach. The results of the case studies show that organic certification of orange production and processing leads to more integrated governance structures in citrus production, as it increases agricultural products’ assets specificity and moral hazard risks in commercialization.institutions, governance, certification, citrus, integration, Agribusiness, Agricultural Finance, Industrial Organization,

Public policies and food security and family farming networks: contributions to the construction of effectiveness indicators.

This work presents a methodology for investigating the performance of public politics regarding food security networks formed in Brazilian municipalities aimed at increasing income and employment in familiar farming. These programs need to further develop the methodologies used for studying their efficiency so that they can reach a new stage in the improvement and use of management tools thereby achieving beteer results of social inclusion and/or food security. This paper constitutes a first effort to bring together indicators for the evaluation of the efficiency of public politicies

COMÉRCIO JUSTO INTERNACIONAL: O CASO DO SUCO DE LARANJA ENTRE O BRASIL E A FRANÇA

This paper is a preliminary analysis of the governance structure of the faire trade of orange juice between Brazil and France. Fair trade is an organizational field composed of complex organizational networks that maintain relations of mutual dependence and share the same values system. As fair trade is a subject that has received relatively little study and presents many particularities, an exploratory study was considered appropriate. Primary and secondary data were collected. In the case of the trade of orange juice between Brazil and France, two commercial networks were identified. The integrated network is constituted by professionals who specialize in fair trade, while the certified network includes more conventional commercial organizations, such as supermarkets. However, although they adopt different functioning mechanisms, in the case of orange juice the importers in the integrated network have integrated themselves into the certified network. In this way, they meet the requirements of the certified network and follow its rules for importing Brazilian orange juice. After analyzing the intrinsic characteristics of the product, the asset specificity, the frequency and the uncertainty of the transactions, the governance structure observed was the hybrid arrangement, in which long-term contracts are used to coordinate relations.transaction costs, governance structures, networks, fair trade, orange juice., Agribusiness, Agricultural Finance, Industrial Organization,

OS ENTRAVES ORGANIZACIONAIS NO SETOR AGROINDUSTRIAL CITRÃCOLA DO ESTADO DE SÃO PAULO

This work aims to present a diagnosis of the main institutional filters for the agroindustrial citriculture chain in São Paulo State. Many of these filters are consolidated into hindrances for the orange business organization in the orange trade channels. These organizational hindrances result from a field research carried out amongst 120 producers in Ribeirão Preto –SP area during the harvest periods ranging from 2003-2004. The identification and analysis of those hindrances allow further advance for understanding the orange producers’ adaptation problems in the Brazilian agroindustrial citriculture organization.organization, institutions, hindrances, agroindustry, citrus juice.,

A COORDENAÇÃO AGROINDUSTRIAL CITRICOLA BRASILEIRA E OS NOVOS RECURSOS DE PODER: DOS POLITICOS AOS JURIDICOS

This work shows that the political and legal resources available to citrus farmers have become as strategic as financial, technological and organizational resources. The study presents an analysis of the Brazilian citrus business governance, which is defined by the use of different strategies among citrus farmers and processing plants: the citrus farmers and their main association use political resources, while some big juice processing plants resort to legal resources. This opposition represents a new obstacle to the achievement of positive results by citrus farmers in the current power network. Court orders demonstrate that orange supply contracts have become a fundamental empowering instrument in the sector, leading to strategic gains for the juice processing plants after four years of significant political conquests by citrus farmers, especially in Sao Paulo state.citrus farmers, power, resources, juice processing plants, citrus business governance, Agribusiness, Agricultural Finance, Industrial Organization,

A coordenação agroindustrial citrícola brasileira e os novos recursos de poder: dos políticos aos jurídicos

O presente trabalho mostra que os recursos políticos e jurídicos tornaram-se tão ou mais estratégicos para citricultores e processadores de suco no Brasil que os próprios recursos financeiros, tecnológicos e organizacionais. Também, apresenta uma análise da governança citrícola brasileira atual, que está pautada por estratégias diferentes entre citricultores e processadoras: os citricultores e sua principal associação pautam suas principais ações nas utilizações de recursos políticos e algumas grandes processadoras de suco avançam com utilizações de recursos jurídicos. Esse embate revela um novo entrave para a conquista de resultados positivos pelos citricultores na rede de poder atual, pois os mandados judiciais revelam que o contrato de fornecimento de laranja tornou-se um instrumento de poder fundamental nessa rede de coordenação, causando ganhos estratégicos para as processadoras de suco após quatro anos de conquistas de recursos políticos significativos por parte dos citricultores, especialmente do estado de São Paulo.------------------------------------This essay shows that the political and legal resources, for citrus farmers, became as much strategic as financial, technological and organizational resources themselves. It This essay shows that the political and legal resources, for citrus farmers, became as much strategic as financial, technological and organizational resources themselves. ItThis essay shows that the political and legal resources, for citrus farmers, became as much strategic as financial, technological and organizational resources themselves. It presents an analysis of Brazilian citrus business governance, which is guided by different strategies between citrus farmers and processing plants: the citrus farmers and their main association guide their actions into using political resources while some big juice processing plants advance by using legal resources. This opposition represents a new obstacle to the conquest of positive results by citrus farmers in the current power network, because court orders shows that the supplying contracts of orange became an instrument of fundamental power into this coordination network, causing strategic gains for the juice processing plants after four years of significant political resource conquests by citrus farmers, specially in Sao Paulo state.Citricultores, recursos de poder, processadores de suco, governança citrícola, citrus farmers, resources of power, juice processing plants, citrus business governance, Agribusiness, Crop Production/Industries,

PERSPECTIVAS DA AGROENERGIA NO BRASIL

Este texto tem por objetivo fazer uma revisão do estágio atual da produção mundial de biocombustíveis, das políticas adotadas nos vários países e das perspectivas de inserção do Brasil neste processo como produtor e exportador de biocombustíveis, conciliando isto com o desenvolvimento econômico e social e com o respeito ao meio-ambiente. Os autores destacam a necessidade de conciliação das ações da iniciativa privada com a adoção de políticas publicas, visto que apenas o “mercado” ainda não é capaz de gerar os incentivos necessários para a conciliação entre a busca de negócios lucrativos e sustentabilidade econômica e social. A metodologia de pesquisa usada foi de revisão bibliográfica e pesquisa de dados estatísticos em publicações especializadas, relatórios de pesquisa e artigos acadêmicos. O texto conclui que o Brasil tem vantagens competitivas na produção de etanol e está se consolidando como um grande exportador. Mas as perspectivas de crescimento com base no mercado interno são mais seguras e duradouras. No caso do Biodiesel, a competitividade é comprometida pelo estágio inicial da produção, sendo que outros países já estão mais avançados. Assim, o Brasil deve se preocupar em ocupar a oportunidade de exportar que existe hoje,mas não pode descuidar de assuntos que podem comprometer a nossa situação no futuro, como a evolução tecnológica e as questões ambientais.------------------------------------------------This text has the objective to make a revision of the actual stage of the world-wide production of biofuels, of the politics adopted in some countries and of the perspectives for brazilian insertion as producer and exporter of biofuels, conciliating this with the economic and social development and the respect to the environment. The authors emphasized the necessity of conciliation with private actions and initiatives and the adoption of public policies, because only the “market” is not capable to generate the necessary incentives for the conciliation between the business-oriented lucrative activities and economic and social support. The research methodology used was bibliographical revision and research of statistical data in specialized publications, academic reports of research and articles. The text concludes that Brazil has competitive advantages in the production of etanol and is if consolidating as a great exporter. But the growth perspectives on the basis of the domestic market are safer and lasting. In the case of the Biodiesel, the competitiveness is affected by the initial status of the production, being that other countries already are more advanced. Thus, Brazil must be worried in occupying the chance to export that it exists today, but cannot neglect of subjects that can compromise our situation in the future, as the technological evolution and the ambient questions.ambiente Institucional, biocombustíveis, políticas-públicas, grupos de interesse, desenvolvimento econômico e social, Institutional Environment, Biofuels, Public Policies, organized groups, economic and social development, Resource /Energy Economics and Policy,

Room temperature strong light-matter coupling in three dimensional terahertz meta-atoms

We demonstrate strong light-matter coupling in three dimensional terahertz meta-atoms at room temperature. The intersubband transition of semiconductor quantum wells with a parabolic energy potential is strongly coupled to the confined circuital mode of three-dimensional split-ring metal-semiconductor-metal resonators that have an extreme sub-wavelength volume (λ/10). The frequency of these lumped-element resonators is controlled by the size and shape of the external antenna, while the interaction volume remains constant. This allows the resonance frequency to be swept across the intersubband transition and the anti-crossing characteristic of the strong light-matter coupling regime to be observed. The Rabi splitting, which is twice the Rabi frequency (2ΩRabi), amounts to 20% of the bare transition at room temperature, and it increases to 28% at low-temperatur