Deposition of chemically reactive and repellent sites on biosensor chips for reduced non-specific binding

The performances of new polymeric materials with excellent optical properties and good machinability have led the biomedical diagnostics industry to develop cheap disposable biosensor platforms appropriate for point of care applications. Zeonor, a type of cycloolefin polymer (COP), is one such polymer that presents an excellent platform for biosensor chips. These polymer substrates have to be modified to have suitable physico-chemical properties for immobilizing proteins. In this work, we have demonstrated the amine functionalization of COP substrates, by plasma enhanced chemical vapour deposition (PECVD), through codeposition of ethylene diamine and 3-aminopropyltriethoxysilane precursors, for building chemistries on the plastic chip. The elemental composition, adhesion, ageing and reactivity of the plasma polymerized film were examined. The Si-O functionality present in amino silane contributed for a good interfacial adhesion of the coating to COP substrates and also acted as a network building layer for plasma polymerization. Wet chemical modification was then carried out on the amine functionalized chips to create chemically reactive isothiocyanate sites and protein repellent fluorinated sites on the same chip. The density of the reactive and repellent sites was altered by choosing appropriate mixtures of homofunctional phenyldiisothiocyanate (PDITC), pentafluoroisothiocyanate (5FITC) and phenylisothiocyanate (PITC) compounds. By tailoring the density of reactive binding sites and protein repellent sites, the non-specific binding of ssDNA has been decreased to a significant extent. © 2010 Elsevier B.V

Patterns of mitochondrial DNA instability in Brassica campestris cultured cells

We previously showed that the mitochondrial DNA (mtDNA) of a Brassica campestris callus culture had undergone extensive rearrangements (i.e. large inversions and a duplication) relative to DNA of the control plant [54]. In this study we observed that after continued growth, the mtDNA of this culture continues to change, with rearranged forms amplifying and diminishing to varying proportions. Strikingly similar changes were detected in the mtDNA profiles of a variety of other long- and short-term callus and cell suspension lines. However, the proportions of parental (‘unrearranged’) and novel (‘rearranged’) forms varied in different cultured cell mtDNAs. To address the source of this heterogeneity, we compared the mtDNA organization of 28 individual plants from the parental seed stock. With the exception of one plant containing high levels of a novel plasmid-like mtDNA molecule, no significant variation was detected among individual plants and therefore source plant variation is unlikely to have contributed to the diversity of mitochondrial genomes observed in cultured cells. The source of this culture-induced heterogeneity was also investigated in 16 clones derived from single protoplasts. A mixed population of unrearranged and rearranged mtDNA molecules was apprent in each protoclone, suggesting that the observed heterogeneity in various cultures might reflect the genomic composition of each individual cell; however, the induction of an intercellular heterogeneity subsequent to the protoplast isolation was not tested and therefore cannot be ruled out. The results of this study support our earlier model that the rapid structural alteration of B. campestris mtDNA in vitro results from preferential amplification and reassortment of minor pre-existing forms of the genome rather than de novo rearrangement. Infrequent recombination between short dispersed repeated elements is proposed as the underlying mechanism for the formation of these minor mtDNA molecules.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43428/1/11103_2004_Article_BF00017914.pd

Sociocultural and epidemiological aspects of HIV/AIDS in Mozambique

<p>Abstract</p> <p>Background</p> <p>A legacy of colonial rule coupled with a devastating 16-year civil war through 1992 left Mozambique economically impoverished just as the human immunodeficiency virus (HIV) epidemic swept over southern Africa in the late 1980s. The crumbling Mozambican health care system was wholly inadequate to support the need for new chronic disease services for people with the acquired immunodeficiency syndrome (AIDS).</p> <p>Methods</p> <p>To review the unique challenges faced by Mozambique as they have attempted to stem the HIV epidemic, we undertook a systematic literature review through multiple search engines (PubMed, Google Scholar™, SSRN, AnthropologyPlus, AnthroSource) using Mozambique as a required keyword. We searched for any articles that included the required keyword as well as the terms 'HIV' and/or 'AIDS', 'prevalence', 'behaviors', 'knowledge', 'attitudes', 'perceptions', 'prevention', 'gender', drugs, alcohol, and/or 'health care infrastructure'.</p> <p>Results</p> <p>UNAIDS 2008 prevalence estimates ranked Mozambique as the 8^thmost HIV-afflicted nation globally. In 2007, measured HIV prevalence in 36 antenatal clinic sites ranged from 3% to 35%; the national estimate of was 16%. Evidence suggests that the Mozambican HIV epidemic is characterized by a preponderance of heterosexual infections, among the world's most severe health worker shortages, relatively poor knowledge of HIV/AIDS in the general population, and lagging access to HIV preventive and therapeutic services compared to counterpart nations in southern Africa. Poor education systems, high levels of poverty and gender inequality further exacerbate HIV incidence.</p> <p>Conclusions</p> <p>Recommendations to reduce HIV incidence and AIDS mortality rates in Mozambique include: health system strengthening, rural outreach to increase testing and linkage to care, education about risk reduction and drug adherence, and partnerships with traditional healers and midwives to effect a lessening of stigma.</p

One step ATRP initiator immobilization on surfaces leading to gradient-grafted polymer brushes

Published: April 30, 2014A method is described that allows potentially any surface to be functionalized covalently with atom transfer radical polymerization (ATRP) initiators derived from ethyl-2-bromoisobutyrl bromide in a single step. In addition, the initiator surface density was variable and tunable such that the thickness of polymer chain grafted from the surface varied greatly on the surfaces providing examples, across the surface of a substrate, of increased chain stretching due to the entropic nature of crowded polymer chains leading toward polymer brushes. An initiator gradient of increasing surface density was deposited by plasma copolymerization of an ATRP initiator (ethyl 2-bromoisobutyrate) and a non-ATRP reactive diluent molecule (ethanol). The deposited plasma polymer retained its chemical ability to surface-initiate polymerization reactions as exemplified by N,N'-dimethyl acrylamide and poly(ethylene glycol) methyl ether methacrylate polymerizations, illustrating linear and bottle-brush-like chains, respectively. A large variation in graft thickness was observed from the low to high chain-density side suggesting that chains were forced to stretch away from the surface interface--a consequence of entropic effects resulting from increased surface crowding. The tert-butyl bromide group of ethyl 2-bromoisobutyrate is a commonly used initiator in ATRP, so a method for covalent linkage to any substrate in a single step desirably simplifies the multistep surface activation procedures currently used.Bryan R. Coad, Katie E. Styan, and Laurence Meaghe

Does the Nominal Exchange Rate Regime Affect the Real Interest Parity Condition?

The real interest partity (RIP) condition combines two cornerstones in international finance, uncovered interest parity (UIP) and ex ante purchasing power parity (PPP). The extent of deviation from RIP is therefore an indicator of the lack of product and financial market integration. This paper investigates whether the nominal exchange rate regime has an impact on RIP. The analysis is based on 15 annual real interest rates and covers a long time span, 1870-2006. Four subperiods are distinguished and linked to fixed and flexible exchange rate regimes: the Gold Standard, the interwar float, the Bretton Woods system and the current managed float. Panel integration techniques are used to increase the power of the tests. Cross section correlation is embedded via common factor structures. The results suggest that RIP holds as a long run condition irrespectively of the exchange rate regimes. Adjustment towards RIP is affected by the institutional framework and the historical episode. Half lives of shocks tend to be lower under fixed exchange rates and in the first part of the sample, probably due to higher price flexibility before WWII. Although barriers to foreign trade and capital controls were substantially removed after the collapse of the Bretton Woods system, they did not lead to lower half lives during the managed float

Parameter heterogeneity, persistence and cross-sectional dependence: new insights on fiscal policy reaction functions for the Euro area

A number of novelties have emerged in the study of the discretionary fiscal policy within the Euro area during the last decade. Among the others, the availability of up-to-date information on fiscal indicators for the years following the Great Recession, the introduction of cutting-edge econometric methods, and a renewed interest about the sustainability of fiscal policy and public debt. The aim of this paper is to address the challenges posed by the estimation of the discretionary fiscal reaction function for the Euro area. We exploit recently introduced testing and estimation strategies for heterogeneous dynamic panels with cross-sectional dependence and propose a new parsimonious approach. Using real-time data over the period 1996-2016, we investigate whether the fiscal policy reaction function is still a benchmark after the Great Recession. We find evidence of strong cross-sectional dependence in the panel, and clear support to a valid cointegration relationship among the main determinants of the function. Newly added covariates, such interest rate spreads, come out to play a relevant role in explaining discretionary actions

Multi-level 3D-tracking of objects integrating velocity estimation based on optical flow and Kalman-filtering

This contribution describes an extensively tested approach to threedimensional tracking of a known polyhedral object at two levels of visual robot control, a position-based tracking level and a velocity-based tracking level. At the higher position-based level, an iterated extended Kalman-Filter is used to track a workpiece at a control-cycle of about two hundred milliseconds. This slower cycle operates on top of the video-rate tracking-loop of the velocity-based tracking level. While features such as vertices, edges, and ellipses extracted from gray-value images are used to adjust the 3D pose-estimate at the higher level of control, optical flow is used to initialise the velocity parameters of the upper level and to locally update poses at the lower level

Spatially-adaptive filtering in a model-based machine vision approach to robust workpiece tracking

The introduction of model-based machine vision into the feedback loop of a robot manipulator usually implies that edge elements extracted from the current digitized video frame are matched to segments of a workpiece model which has been projected into the image plane according to the current estimate of the relative pose between the recording video camera and the workpiece to be tracked. In the case in which two (nearly) parallel projected model segments are close to each other in the image plane, the association between edge elements and model segments can become ambiguous. Since mismatches are likely to distort the state variable update step of a Kalman-Filter-based tracking process, suboptimal state estimates may result which can potentially jeopardize the entire tracking process. In order to avoid such problems, spatially adjacent projected model segments in the image plane have been suppressed by an augmented version of a hiddenline algorithm and thereby excluded from the edge ele ment association and matching step - see, e.g., Tonko et al., 1CRA'97, pp. 3166-3171. Here, we study an alternative approach towards increasing the robustness of a machine-vision-based tracker, exploiting the fact that a gradient filter can be adapted to the spatial characteristics of the local grayvalue variation: the filter mask is compressed in the gradient direction and enlarged perpendicular to the gradient direction, i.e. along the edge. We investigate the effect which such a spatially adaptive gradient filter for the extraction of edge elements from image frames exerts upon the association between edge elements and model segments, upon the subsequent fitting process in the update step, and thereby upon the robustness of the entire model-based tracking approach