3,194 research outputs found
Hybrid pH-Responsive Au@p4VP Microgels as Platform for Selective SERS Analysis
We present the synthesis a of pH-responsive core@shell hybrid microgel. This colloidal system is formed by a 55 nm Au core individually covered by a polymeric pH-sensitive shell of poly(4-vinylpyridine), that we denote as Au@p4VP. Initially, we control the microgel thickness from 51 to 10 nm, and we confirm the pH- responsive capability of Au@p4VP by DLS measurements, showing a swelling degree, which depends on the pH of the media and the crosslinker density within the polymer network. We also prove the hybrid structure by plotting the UV-vis spectra at different pH values, showing a surface plasmon band displacement in function of pH. Thus, at acidic pH the microgel swells due to the electrostatic repulsion created into the polymer matrix, while at high pH, the microgel structure collapses because of the reduction in the electrostatic repulsion and the increment of the hydrophobic interactions. This capability is exploited to introduce doxorubicin molecules into the microgel network which are detected by surface- enhanced Raman spectroscopy (SERS). After increasing the pH of the solution, the captured molecules are brought in close proximity to the surface of the metallic core, enhancing its detection by SERS.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
El rol de las Áreas Naturales Periurbanas para la Resiliencia al Cambio Climático de las Metrópolis : el Caso de la Ciudad de México
La metropolización es una característica dominante de los procesos de crecimiento urbano a nivel mundial. Asimismo, uno de los principales problemas que enfrentan las metrópolis es el cambio climático. Con el objeto de caracterizar la adaptación al cambio climático en las metrópolis, la literatura reciente ha utilizado el concepto de resiliencia como modelo teórico para entender la forma en la que una ciudad se constituye como un sistema socio-ecológico, el cual tiene la capacidad y la habilidad para resistir los embates del cambio climático. El presente artículo caracteriza la relevancia que tienen las Áreas Naturales Protegidas periurbanas de la Zona Metropolitana del Valle de México y su contribución para la resiliencia general de dicho sistema urbano. El artículo contiene dos principales contribuciones, primero, utiliza el caso de la Ciudad de México para ilustrar la forma en la que una metrópoli se constituye como un sistema socio-ecológico con potencial y habilidad para resistir los efectos esperados del cambio climático; y segundo, caracteriza la importancia y la forma en la que las áreas naturales protegidas metropolitanas coadyuvan a incrementar la resiliencia urbana.Metropolization is a dominant feature of the processes of urban growth worldwide. Furthermore, one of the main problems faced by the metropolis is climate change. In order to characterize the adaptation to climate change in the metropolis, recent literature has used the concept of resilience as a theoretical framework to understand the way in which a city is constituted as a Socio-Ecological System with the capability and the ability to resist the onslaught of climate change. The present article characterizes the relevance of Natural Protected Areas in the Metropolitan Area of the Valley of Mexico and its contribution to the overall resilience of the urban system. The article contains two main contributions, first, it uses the case of Mexico City to illustrate the way in which a metropolis can be understood as a socio-ecological system with potential and ability to resist the expected effects of climate change; and second, it characterizes the importance and the way in which the metropolitan Natural Protected Areas increase urban resilience
Russia's Great Power Ambitions: The Role of Siberia, the Russian Far East, and the Arctic in Russia's Contemporary Relations with Northeast Asia
Being at the confluence of two worlds – East and West – has had long-term influence on how Russia has thought of its national identity, in particular prompting the question: to what extent is it joining or resisting these two worlds? This thesis argues that Russia’s self-perception of being a great power – greatpowerness - defines its status and position in the world. This ‘greatpowerness’ is a central element of Russia’s national identity and exerts huge influence in the country’s foreign policy making. Under the presidency of Vladimir Putin, Russia has established a long-term project to develop and improve living conditions in Asiatic Russia, and advance its integration into Northeast Asia.
This thesis pursues a research study focusing on these problems: Russia’s insistence on its great power status and the idea of Russia as a great power straddling the West and Asia as a key demand of national identity. The thesis tries to explain how Russian foreign policy reflects this; but also how Asiatic Russia remains a central element defining and promoting this national identity and its quest for great power status. This thesis aims to examine how the aforementioned ideas relate to the apparent necessity of Russia to develop Asiatic Russia and integrate it into Northeast Asia and the broader Asia-Pacific region, pointing out to the dilemmas between cooperation and security issues. The function and perception of Asiatic Russia has never been exclusively internal or external but has always arisen out of the interaction of the two. Therefore this thesis does not only study changes in Asiatic Russia in the post-Soviet period; but also the new external conditions in Northeast Asia.
This thesis attempts to connect three aspects—national identity, geographical settings, and external strategy, to determine the place of Siberia, the Russian Far East, and the Arctic in Russia’s contemporary relations with Northeast Asian countries
Access to land-based resources under the influence of land reform: a case study from an agrarian community in Mexico
This study provides important empirical and analytical insights that represent a step forward towards a deeper and better understanding of the effects of land reform and land policies on the distribution of access to land-based resources. It explores the extent to which the process of land reform during the early 1990s, and the subsequent implementation of complementary land policies and programmes brought deep modifications to the way in which agrarian communities obtain benefits from resources.
The empirical evidence on which this research is based consists of both qualitative and quantitative data elicited by a combination of research methods applied to a case study design. The case study chosen is San Francisco Oxtotilpan, an agrarian community in Mexico‟s central highlands that is home to the smallest indigenous group in the region: the Matlatzinca.
The theoretical and analytical framework designed takes into account the main scholarship on access to natural resources. This extended analytical framework of access to land-based resources provides a characterization of access mechanisms that disentangle the complex set of cultural, socio-economic and political processes underlying access to land-based resources. It enables an assessment of the effects of the implementation of land reform-related policies and programmes over the different ways in which members of the agrarian community benefit from land-based resources.
The study concludes that the implementation of land policies in Mexico since the early 1990s has brought deep modifications in the local governance of land-based resources. It illustrates that the differential distribution of benefits from land-based resources depends on households‟ ability to use a set of access mechanisms to gain, control or maintain the flux of benefits from land-based resources. Results show that when it comes to land-based resource governance, the implementation of land policies and programmes has produced conflicts between the agrarian community and external politico-legal institutions –especially from the State. Furthermore, it modified the internal structure of the agrarian community, and consequently, the complex set of mechanisms that shape the distribution of access to land-based resources available
Evidence for replication of human endogenous retroviruses type-K (HERV-K) in HIV-1 positive patients
Unemployment insurance in Chile: lessons from a high inequality developing country
One of the most complex social policy issues that developing countries commonly face is the question of how they can protect the unemployed. However, the analysis of unemployment insurance (UI) in developing economies with large informal sectors is in its infancy, with few papers providing solid empirical evidence. This paper makes several contributions to the development literature: first, it applies Chetty’s 2008 landmark work on UI to a developing country (Chile) and shows that the moral hazard effects expected by policy makers, who designed the system are minimal, while liquidity effects were entirely neglected. By means of an RDD, it analyses the Chilean UI system using a large sample of administrative data, which allows for an extremely precise analysis of how the system is working, thus providing invaluable empirical lessons for other developing countries. Second, this paper shows that it is not enough merely to quantify an effect such as moral hazard, but to understand its causes and implications. An extended unemployment period stemming from moral hazard has extremely different welfare implications than one stemming from a liquidity effect and should therefore result in different policy recommendations. Third, our results also highlight that the Chilean UI system is regressive overall, as it protects workers with higher income levels and more stable jobs much more than it protects vulnerable workers, who are also much more likely to become unemployed. Fourth, this paper shows that it is essential that developing countries should take into account the specific labour market and macroeconomic context when designing social policies as the incentives embedded in such a policy may not be enough to compensate for the limitations that arise from the structure of a labour market. This research thus has implications for many developing countries, which may also be considering the implementation of some form of UI and/or the partial or complete replacement of existing severance pay legislation with continuous contributions to individual savings accounts, as recommended by the international development institutions. Furthermore, even high-income developing countries, such as Chile, cannot rely on unemployment insurance alone when it comes to protecting workers from the fallout of an economic crisis or rapid changes in the labour market that generate unemployment. Any UI system must also be linked to other social protection mechanisms to provide complimentary benefits to workers with precarious jobs
Tripod-shaped penta (p-phenylene)s for the functionalization of silicon surfaces
In order to obtain nanostructured thin films to be used in biosensor devices, several chemical functionalization methods have been developed, such as Click chemistry or Suzuki carbon-carbon coupling reactions on surfaces.1
With the aim to control the orientation and spacing between grafted functional groups on a surface, tripodal oligo (p-phenylene)s have become the ideal anisotropic adsorbates due to their shape-persistent and self-standing characteristics.2
Here we report the synthesis and characterization of several tripod-shaped oligo(p-phenylene)s molecules with legs composed of five phenylene units, compounds 1, 2 and 3. In these structures, each leg is end-capped with an NH-Boc, NH2 and N3 group, respectively. The functional arm contains an acetylene group. The presented synthesis has as key step the Pd-catalyzed Suzuki cross-coupling reaction. In particular, a iodine derivative from the silicon core molecule reacts with the appropriate tetra(p-phenylene) boron derivative, thus generating the final tripod-shaped structure. The azide end-capped leg in 3 is specifically designed for its covalent incorporation on alkynyl terminated silicon surfaces by an easy and reproducible way. As a preliminary study, we present the alkynyl-functionalized silicon wafers nanostructuration with tripod 3 through the cooper catalyzed alkyne-azide cycloaddition (CuAAC) click reaction.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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