Investment, dynamic consistency and the sectoral regulator's obective

We explore the separation of powers between the legislative and the executive branch of government as a way of overcoming the dynamic consistency problem of regulatory policy towards investment. We model the industry as a regulated duopoly. The incumbent is a vertically integrated firm that owns a wholesaler and a retailer. The entrant owns a retailer. Either retailer needs access to the input produced by the wholesaler to operate. The incumbent can make an investment that improves the quality of the input produced by the wholesaler. The regulator sets the access price and is unable to commit. The legislator sets the regulator's objective function and is able to commit. We derive general conditions under which having the legislator distort the regulator's objective function away from social welfare allows increasing the range of parameter values for which it is possible to induce socially desirable investment. --Investment,Dynamic Consistency,Regulator's Objective

Can Vertical Separation Reduce Non-Price Discrimination and Increase Welfare?

We investigate if vertical separation reduces non-price discrimination and increases welfare. Consider an industry consisting of a vertically integrated firm and an independent retailer, which requires access to the vertically integrated firm's wholesaler services. The wholesaler can degrade the quality of input it supplies to either of the retailers. Discrimination occurs if one of the retailers is supplied an input of lower quality than its rival. We show that separation of the vertically integrated firm reduces discrimination against the independent retailer, although it does not guarantee no-discrimination. Furthermore, with separation, the wholesaler may discriminate against the vertically integrated firm's retailer. Vertical separation impacts social welfare through two e¤ects. First, through the double-marginalization effect, which is negative. Second, through the quality degradation effect, which can be positive or negative. Hence, the net welfare impact of vertical separation is negative or potentially ambiguous.Vertigal integration; Vertical separation; Non-price discrimination.

Thermal conductivity of nanoporous materials: Where Is the limit?

Producción CientíficaNowadays, our society is facing problems related to energy availability. Owing to the energy savings that insulators provide, the search for effective insulating materials is a focus of interest. Since the current insulators do not meet the increasingly strict requirements, developing materials with a greater insulating capacity is needed. Until now, several nanoporous materials have been considered as superinsulators achieving thermal conductivities below that of the air 26 mW/(m K), like nanocellular PMMA/TPU, silica aerogels, and polyurethane aerogels reaching 24.8, 10, and 12 mW/(m K), respectively. In the search for the minimum thermal conductivity, still undiscovered, the first step is understanding heat transfer in nanoporous materials. The main features leading to superinsulation are low density, nanopores, and solid interruptions hindering the phonon transfer. The second crucial condition is obtaining reliable thermal conductivity measurement techniques. This review summarizes these techniques, and data in the literature regarding the structure and thermal conductivity of two nanoporous materials, nanocellular polymers and aerogels. The key conclusion of this analysis specifies that only steady-state methods provide a reliable value for thermal conductivity of superinsulators. Finally, a theoretical discussion is performed providing a detailed background to further explore the lower limit of superinsulation to develop more efficient materials.Ministerio de Ciencia, Innovación y Universidades - (grant FPU17/03299)Ministerio de Ciencia, Innovación y Universidades - (project RTI2018-098749-B-I00)Junta de Castilla y León y Ente Público Regional de la Energía de Castilla y León (EREN) - (Grant VA202P20)Junta de Castilla y León y Fondo Europeo de Desarrollo Regional (FEDER) - (grant CLU-2019-04

Incorporação de polímeros inteligentes em aerogéis à base de sílica

Dissertação de Mestrado Integrado em Engenharia Química apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbr

Environmental cleaning and recovery of heavy metals via functionalization of silica aerogels

Tese de Doutoramento em Engenharia Química apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.Environmental pollution is a severe issue that might cause permanent changes, such as the destruction of ecosystems and loss of biodiversity. Heavy metals are the main pollutant in European soils and groundwater. Their main source are human activities, the most relevant being mining and ore processing. Their non-biodegradability causes accumulation in the environment and the remediation of contaminated sites is difficult and might not be possible to do in situ. Thus, the preservation of natural environments is dependent on minimizing pollutant emissions, with effluent treatment being one possible approach. In this thesis the removal via sorption of copper, lead, cadmium and nickel from water is studied. These were selected due to their current relevance based on wide application, economic value, high toxicity and emissions. The focus of the work is the development of adsorbents for these metals, achieved by the synthesis of organically modified silica aerogels and xerogels, and the study of the sorption process. The goal is the development of a multipurpose solution, able to remove all pollutants, as well as producing selective copper and nickel adsorbents, due to high economic value of these metals. The adsorbents are synthesized though acid-base catalyzed sol-gel chemistry. The surface chemistry modification is achieved by using precursors containing organic moieties of interest. When appropriate, the organic groups on the precursors are modified prior to the gel’s synthesis. The effects of the drying stage, via supercritical fluids extraction with carbon dioxide or via evaporative drying, on the final material’s properties are also assessed. The adsorbents are characterized structurally, chemically and thermally. To remove all cations under study, the silica matrixes are modified with organic groups containing sulfur (thiol groups) or nitrogen (e.g., amine) electron donor atoms, resulting in several different formulations. The study of silica matrixes modified with thiol groups is presented in Chapter 4 whilst the study of nitrogen modified matrixes is in Chapter 5. The modification of the silica matrix was found to reduce the specific surface area. Formulations containing amine groups are densified when dried by evaporation, severely decreasing porosity and surface area, the latter as low as 2 m2 g−1. Comparing with pristine (non-modified) matrixes, it was revealed that the surface chemistry modification is required for this application, with the former only interacting with lead (the removal for the remainder cations is <9% with a starting concentration of 50 mg L−1). In general, the modified matrixes interact with the cations in solution, with isocyanurate and urea groups being notable exceptions (removal <10% with a starting cation concentration of 50 mg L−1, except for lead). Amine groups are the most efficient of those tested, improving even the adsorptive performance of thiol modified sorbents, even on materials of reduced porosity. The in-depth study of selected formulations revealed that the sorption takes a few hours, and the adsorbent-cation interactions are strong and not easily reversible. The aerogel containing primary and secondary amines (A_A+3A) was chosen as the best multipurpose adsorbent (Langmuir adsorption capacity of 60 mg g−1 for copper, 347 mg g−1 for lead, 83 mg g−1 for cadmium and 66 mg g−1 for nickel). Its study with binary mixtures of cations revealed that it is selective for copper up to six hours of the adsorption process (selectivity of 2.6 in relation to nickel and 49 in relation to cadmium). Thus, A_A+3A is both the multipurpose solution and the copper selective one, and the outcome of the adsorption is controlled by the operating conditions. Desorption of the cations from this material is possible with acids, but it leads to partial loss of the sportive performance, to a third of the original one. The recovery of desorbed copper can be achieved via electrodeposition. The modification of the silica matrix with certain ionophores led to the synthesis of selective aerogels. The azole modification of the silica generated a material that interacts poorly with the cations; hence a significant removal of copper was not observed. This result was attributed to the possible inaccessibility of the azole to the cations, due to the aerogel’s porous structure and steric hindrance. The nickel selective, salen based adsorbent features aerogel-like characteristics, due to a small shrinkage of 10% after evaporative drying, and has a high affinity for nickel, being its removal higher and unaffected by the presence of competing ions. Despite the isotherms being shaped like a BET curve, the existence of cation multilayers is unlikely, and the aerogel-cation interactions are defined by the hydrated radius of the cation. Its estimated selectivity reveals that this adsorbent is twice as selective for nickel than for copper and 9 times than for cadmium. Due to the high affinity with nickel, its desorption is very limited. This work allowed to demonstrate the high adsorptive performance of organically modified silica aerogels for heavy metals relevant in some industrial effluents, soil and water, when compared with other commercial or researched adsorbents. The great chemical versatility of the silica matrix also allowed to adapt its surface chemistry to obtain more general use or selective solutions, taking advantage of the high porosity and surface area of aerogels.A poluição é um grave problema que pode conduzir a alterações irreversíveis, como a destruição de ecossistemas e perda de biodiversidade. Os metais pesados são os principais contaminantes de solos e águas subterrâneas na Europa. A sua principal fonte de emissão são atividades humanas, sendo as indústrias de extração e processamento de minérios as mais relevantes. Por serem poluentes não biodegradáveis, acumulam-se e a remediação de áreas contaminadas é difícil e nem sempre possível in situ. Desta forma, a preservação do meio ambiente passa pela minimização das emissões poluentes, sendo o tratamento de efluentes uma das estratégias para tal. Nesta tese é estudada a remoção de cobre, chumbo, cádmio e níquel de água, através do processo de adsorção. Esta seleção recai na elevada importância destes quatro metais na sociedade atual, quer seja pela sua ampla utilização e valor económico, ou pelas elevadas toxicidade e emissões. O trabalho realizado foca-se no desenvolvimento de adsorventes para estes metais, através da síntese de aerogéis e xerogéis de sílica organicamente modificados e caracterização do processo de sorção dos metais por estes. Pretende-se desenvolver adsorventes que possam funcionar como uma solução transversal, removendo todos os metais contaminantes, mas também produzir soluções seletivas para cobre e níquel, devido ao seu valor económico. Os adsorventes são sintetizados através da metodologia sol-gel, catalisada por ácidos e bases, sendo que a modificação da sua química de superfície é conseguida através de co-precursores organicamente modificados. Quando conveniente, a modificação dos grupos orgânicos dos precursores é feita a priori da síntese do adsorvente. A influência do processo de secagem, por extração com dióxido de carbono supercrítico ou por evaporação, nas propriedades do material final foi também avaliada. Os adsorventes foram alvo de caracterização física/estrutural, química e térmica. Com o objetivo de remover todos os metais em estudo, a modificação das matrizes de sílica é feita através de grupos orgânicos contendo enxofre (tiol) ou azoto (p. ex. amina) como átomos dadores de electrões, dando origem à síntese de diferentes formulações. O estudo das matrizes modificadas com grupo tiol encontra-se no Capítulo 4 enquanto que o estudo das matrizes com azoto encontra-se no Capítulo 5. A modificação da matriz de sílica conduz a uma diminuição de área de superfície específica. Quando as formulações contêm grupos amina, a sua secagem por evaporação densifica o material, levando a uma perda acentuada de porosidade e área de superfície específica, esta última podendo chegar a 2 m2 g−1. A comparação com um aerogel não modificado revelou que a modificação da sílica é necessária para esta aplicação, pois o material não modificado apenas interagiu com chumbo (remoção para os restantes catiões <9% com uma concentração inicial de 50 mg L−1). A generalidade das modificações verificou-se capaz de interagir com os metais em solução, sendo os grupos isocianurato e ureia as exceções (remoção ≤10% com uma concentração inicial de catião 50 mg L−1, exceto para chumbo). Os grupos amina são mais eficientes que os demais testados, tendo inclusivamente melhorado o desempenho sortivo de matrizes modificadas com tiol, mesmo em materiais de reduzida porosidade. O estudo mais detalhado de formulações selecionadas revelou que processo de sorção é concluído em algumas horas e as interações com os catiões são fortes e dificilmente reversíveis. Foi selecionado o aerogel contendo aminas primárias e secundárias (A_A+3A) como o melhor adsorvente transversal para os catiões em estudo (capacidade de adsorção de Langmuir de 60 mg g−1 para cobre, 347 mg g−1 para chumbo, 83 mg g−1 para cádmio e 66 mg g−1 para níquel). O seu estudo em misturas binárias permitiu concluir que até seis horas de adsorção este material revela um comportamento seletivo para cobre (2.6 em relação a níquel e até 49 a cádmio). Assim o adsorvente A_A+3A é simultaneamente uma solução transversal e seletiva para cobre, sendo o resultado da adsorção controlado pelas condições operatórias. A sua regeneração por via química com ácidos é possível, mas conduz à perda parcial de características adsortivas, para cerca de um terço da capacidade inicial. A recuperação do cobre dessorvido pode ser feita por eletrólise. A modificação da matriz de sílica com certos ionóforos conduziu ao desenvolvimento de aerogéis seletivos. A introdução de azóis na sílica resultou num material que não interage com os catiões, não se verificando uma remoção significativa de cobre. Tal facto deve-se à inacessibilidade dos átomos dadores de electrões por parte dos catiões, devido à microestrutura do material e a repulsão estérea dos grupos funcionais vizinhos. O adsorvente baseado num salen revelou propriedades estruturais semelhantes às de um aerogel mesmo após secagem evaporativa, devido a um encolhimento reduzido (10%), e tem uma acrescida afinidade para o níquel, sendo a sua capacidade remoção para este último superior e inalterada pela presença dos demais catiões. Apesar das isotérmicas apresentarem uma forma do tipo BET, a existência de multicamadas de catiões não é plausível e o tipo de interações adsorvente-adsorvato é essencialmente definido pelo raio iónico dos catiões. A seletividade estimada revela que este adsorvente é duas vezes mais seletivo para níquel do que para cobre e até 9 vezes para cádmio. Devido à forte interação com níquel a sua dessorção é muito limitada. Assim, este trabalho permitiu demonstrar a elevada capacidade adsorptiva dos aerogéis de sílica modificados organicamente para metais pesados com presença relevante em efluentes de algumas indústrias, bem como em solos e águas, quando comparados com outros adsorventes comerciais ou em investigação. A assinalável versatilidade química da rede de sílica permite ainda adaptar facilmente a química de superfície destes materiais para obter soluções de remoção mais amplas ou seletivas, tirando cumulativamente partido da elevada porosidade e área de superfície dos aerogéis

Incentives to Invest and to Give Access to Non-Regulated Next Generation Networks

We analyze the incentives of a telecommunications incumbent to invest and give access to a downstream entrant to a next generation network. We model the industry as a duopoly, where a vertically integrated incumbent and a downstream entrant, that requires access to the incumbent's network, compete on Hotelling's line. The incumbent can invest in the deployment of a NGN that improves the quality of the retail services. Access to the old network is regulated, but access to the new network is not. If the innovation is drastic, the incumbent always invests in the NGN, but does not give access to the entrant. If the innovation is non-drastic and if the access price to the old network is low, the incumbent voluntarily gives access to the NGN. If the innovation is non-drastic, there is no monotonic relation between the access price to the old network and the incumbent's incentives to invest. A regulatory moratorium emerges as socially optimal, if the innovation is large but non-drastic. We also analyze the case where both firms can invest in the deployment of a NGN.Next Generation Networks, Investment, Access, Regulation

Can two-part tariffs promote efficient investment on next generation networks?

We analyze if two-part access tariffs solve the dynamic consistency problem of the regulation of next generation networks. We model the industry as a duopoly, where a vertically integrated incumbent and a downstream entrant, that requires access to the incumbent's network, compete on Hotelling's line. The incumbent can invest in the deployment of a next generation network that improves the quality of the retail services. We have three main results. First, we show that if the regulator can commit to a policy, a regulatory moratorium may emerge as socially optimal. Second, we show that if the regulator cannot commit to a policy, it can induce investment only when the investment cost is low. Third, we show that in this case, two-part tariffs involve very large payments from the entrant to the incumbent.Next generation networks Investment Regulation Dynamic consistency

Reduced Chitosan as a Strategy for Removing Copper Ions from Water

Toxic heavy metals are priority pollutants in wastewater, commonly present in dangerous concentrations in many places across the globe. Although in trace quantities copper is a heavy metal essential to human life, in excess it causes various diseases, whereby its removal from wastewater is a necessity. Among several reported materials, chitosan is a highly abundant, non-toxic, low-cost, biodegradable polymer, comprising free hydroxyl and amino groups, that has been directly applied as an adsorbent or chemically modified to increase its performance. Taking this into account, reduced chitosan derivatives (RCDs 1-4) were synthesised by chitosan modification with salicylaldehyde, followed by imine reduction, characterised by RMN, FTIR-ATR, TGA and SEM, and used to adsorb Cu(II) from water. A reduced chitosan (RCD3), with a moderate modification percentage (43%) and a high imine reduction percentage (98%), proved to be more efficient than the remainder RCDs and even chitosan, especially at low concentrations under the best adsorption conditions (pH 4, RS/L = 2.5 mg mL-1). RCD3 adsorption data were better described by the Langmuir-Freundlich isotherm and the pseudo-second-order kinetic models. The interaction mechanism was assessed by molecular dynamics simulations, showing that RCDs favour Cu(II) capture from water compared to chitosan, due to a greater Cu(II) interaction with the oxygen of the glucosamine ring and the neighbouring hydroxyl groups