Using macromolecular-crystallography beamline and microfluidic platform for small-angle diffraction studies of lipidic matrices for membrane-protein crystallization.

Macromolecular-crystallography (MX) beamlines routinely provide a possibility to change X-ray beam energy, focus the beam to a size of tens of microns, align a sample on a microdiffractometer using on-axis video microscope, and collect data with an area-detector positioned in three dimensions. These capabilities allow for running complementary measurements of small-angle X-ray scattering and diffraction (SAXS) at the same beamline with such additions to the standard MX setup as a vacuum path between the sample and the detector, a modified beam stop, and a custom sample cell. On the 21-ID-D MX beamline at the Advanced Photon Source we attach a vacuum flight tube to the area detector support and use the support motion for aligning a beam stop built into the rear end of the flight tube. At 8 KeV energy and 1 m sample-to-detector distance we can achieve a small-angle resolution of 0.01A-1 in the reciprocal space. Measuring SAXS with this setup, we have studied phase diagrams of lipidic mesophases used as matrices for membrane-protein crystallization. The outcome of crystallization trials is significantly affected by the structure of the lipidic mesophases, which is determined by the composition of the crystallization mixture. We use a microfluidic chip for the mesophase formulation and in situ SAXS data collection. Using the MX beamline and the microfluidic platform we have demonstrated the viability of the high-throughput SAXS studies facilitating screening of lipidic matrices for membrane-protein crystallization.

Local health policy development processes in the Netherlands: an expanded toolbox for health promotion

Although much research has been done on the existence and formation of risk and issue based health policies, there is only little insight in health policy development processes in a broader context. This hampers intervention in these policy processes to adequately develop integrated and effective health policies. Legislation in the Netherlands requires municipalities to develop and implement local health policies. These policies are supposed to aim at the promotion of health across sectors and with a strong community involvement. Health policy development processes have been studied in four Dutch municipalities. For each case, we identified a range of stakeholders and monitored the change or stability of their characteristics over 3 years. In addition, for each case, three overlaying maps of networks were made addressing communication and collaboration actions within the defined set of stakeholders. We point out a number of barriers which impede integrated policy development at the local level: the importance given to local health policy, the medical approach to health development, the organizational self-interest rather than public health concern, the absence of policy entrepreneurial activity. Furthermore, this article advocates the use of complementary theoretical frameworks and the expansion of the methodological toolbox for health promotion. The value of stakeholder and network analysis in the health promotion domain, at this stage, is two-fold. First, mapping relevant actors, their positions and connections in networks provides us with insight into their capacity to participate and contribute to health policy development. Second, these new tools contribute to a further understanding of policy entrepreneurial roles to be taken up by health promotion professionals and health authorities in favour of the socio-environmental approach to health. Notwithstanding the value of this first step, more research is required into both the practical application as well as in the theoretical connections with, for example, Multiple Streams theory. (AU)

Local health policy development processes in the Netherlands: an expanded toolbox for health promotion

Although much research has been done on the existence and formation of risk and issue based health policies, there is only little insight in health policy development processes in a broader context. This hampers intervention in these policy processes to adequately develop integrated and effective health policies. Legislation in the Netherlands requires municipalities to develop and implement local health policies. These policies are supposed to aim at the promotion of health across sectors and with a strong community involvement. Health policy development processes have been studied in four Dutch municipalities. For each case, we identified a range of stakeholders and monitored the change or stability of their characteristics over 3 years. In addition, for each case, three overlaying maps of networks were made addressing communication and collaboration actions within the defined set of stakeholders. We point out a number of barriers which impede integrated policy development at the local level: the importance given to local health policy, the medical approach to health development, the organizational self-interest rather than public health concern, the absence of policy entrepreneurial activity. Furthermore, this article advocates the use of complementary theoretical frameworks and the expansion of the methodological toolbox for health promotion. The value of stakeholder and network analysis in the health promotion domain, at this stage, is two-fold. First, mapping relevant actors, their positions and connections in networks provides us with insight into their capacity to participate and contribute to health policy development. Second, these new tools contribute to a further understanding of policy entrepreneurial roles to be taken up by health promotion professionals and health authorities in favour of the socio-environmental approach to health. Notwithstanding the value of this first step, more research is required into both the practical application as well as in the theoretical connections with, for example, Multiple Streams theory. (AU)

Local health policy development processes in the Netherlands: an expanded toolbox for health promotion.

Although much research has been done on the existence and formation of risk and issue based health policies, there is only little insight in health policy development processes in a broader context. This hampers intervention in these policy processes to adequately develop integrated and effective health policies. Legislation in the Netherlands requires municipalities to develop and implement local health policies. These policies are supposed to aim at the promotion of health across sectors and with a strong community involvement. Health policy development processes have been studied in four Dutch municipalities. For each case, we identified a range of stakeholders and monitored the change or stability of their characteristics over 3 years. In addition, for each case, three overlaying maps of networks were made addressing communication and collaboration actions within the defined set of stakeholders. We point out a number of barriers which impede integrated policy development at the local level: the importance given to local health policy, the medical approach to health development, the organizational self-interest rather than public health concern, the absence of policy entrepreneurial activity. Furthermore, this article advocates the use of complementary theoretical frameworks and the expansion of the methodological toolbox for health promotion. The value of stakeholder and network analysis in the health promotion domain, at this stage, is two-fold. First, mapping relevant actors, their positions and connections in networks provides us with insight into their capacity to participate and contribute to health policy development. Second, these new tools contribute to a further understanding of policy entrepreneurial roles to be taken up by health promotion professionals and health authorities in favour of the socio-environmental approach to health. Notwithstanding the value of this first step, more research is required into both the practical application as well as in the theoretical connections with, for example, Multiple Streams theory.

Mechanism of CO oxidation on Pt(111) in alkaline media.

Electrochemical techniques, coupled with in situ scanning tunneling microscopy, have been used to examine the mechanism of CO oxidation and the role of surface structure in promoting CO oxidation on well-ordered and disordered Pt(111) in aqueous NaOH solutions. Oxidation of CO occurs in two distinct potential regions: the prepeak (0.25-0.70 V) and the main peak (0.70 V and higher). The mechanism of reaction is Langmuir-Hinshelwood in both regions, but the OH adsorption site is different. In the prepeak, CO oxidation occurs through reaction with OH that is strongly adsorbed at defect sites. Adsorption of OH on defects at low potentials has been verified using charge displacement measurements. Not all CO can be oxidized in the prepeak, since the Pt-CO bond strength increases as the CO coverage decreases. Below theta(CO) = 0.2 monolayer, CO is too strongly bound to react with defect-bound OH. Oxidation of CO at low coverage occurs in the main peak through reaction with OH adsorbed on (111) terraces, where the Pt-OH bond is weaker than on defects. The enhanced oxidation of CO in alkaline media is attributed to the higher affinity of the Pt(111) surface for adsorption of OH at low potentials in alkaline media as compared with acidic media.

Microfluidic arrays of fluid-fluid diffusional contacts as detection elements and combinatorial tools.

This paper describes microfluidic systems that can be used to investigate multiple chemical or biochemical interactions in a parallel format. These three-dimensional systems are generated by crossing two sets of microfluidic channels, fabricated in two different layers, at right angles. Solutions of the reagents are placed in the channels; in different modes of operation, these solutions can be either flowing or stationary-the latter is important when one set of channels is filled with viscous gels with immobilized reagents. At every crossing, the channels are separated either by a single membrane or by a composite separator comprising a membrane, a microwell, and a second membrane. These components allow diffusive mass transport and minimize convective transport through the crossing. Polycarbonate membranes with 0.1-1-microm vertical pores were used to fabricate the devices. Each crossing of parallel channels serves as an element in which chemical or biochemical interactions can take place; interactions can be detected by monitoring changes in fluorescence and absorbance. These all-organic systems are straightforward to fabricate and to operate and may find applications as portable microanalytical systems and as tools in combinatorial research.

Fabrication inside microchannels using fluid flow.

This Account summarizes techniques for carrying out microfabrication of structures with dimensions down to 10 microm in microchannels that are 0.02-2 mm wide. These methods are largely based on the exploitation of laminar flow at low Reynolds number (Re) to control the spatial delivery of reagents. These methods are illustrated by fabrication of fibers, microelectrode arrays, arrays of crystals, and patterns of proteins and cells.

Patterning electro-osmotic flow with patterned surface charge.

This Letter reports the measurement of electro-osmotic flows (EOF) in microchannels with surface charge patterned on the 200 microm scale. We have investigated two classes of patterns: (1) Those in which the surface charge varies along a direction perpendicular to the electric field used to drive the EOF; this type of pattern generates multidirectional flow along the direction of the field. (2) Those in which the surface charge pattern varies parallel to the field; this pattern generates recirculating cellular flow, and thus causes motion both parallel and perpendicular to the external field. Measurements of both of these flows agree well with theory in the limit of thin double layers and low surface potential.

Patterning cells and their environments using multiple laminar fluid flows in capillary networks.

This paper describes the use of laminar flow of liquids in capillary systems to pattern the cell culture substrate, to perform patterned cell deposition, and to pattern the cell culture media. We demonstrate the patterning of the cell culture substrate with different proteins, the patterning of different types of cells adjacent to each other, the patterned delivery of chemicals to adhered cells, and performing enzymatic reactions over select cells or over a portion of a cell. This method offers a way to simultaneously control the characteristics of the surface to which cells are attached, the type of cells that are in their vicinity, and the kind of media that cells or part of a cell are exposed to. The method is experimentally simple, highly adaptable, and requires no special equipment except for an elastomeric relief that can be readily prepared by rapid prototyping.