Microfluidic chips for cells capture using 3-D hydrodynamic structure array

Microfluidic chips were designed and fabricated to capture cells in a relative small volume to generate the desired concentration needed for analysis. The microfluidic chips comprise three-dimensional (3-D) cell capture structures array fabricated in PDMS. The capture structure includes two layers. The first layer consists of spacers to create small gap between the upper layer and glass. The second layer is a sharp corner U-shaped compartment with sharp corners at the fore-end. And another type capture structure with Y-shaped fluidic guide has been designed. It was demonstrated that the structures can capture cells in theory, using Darcy–Weisbach equation and COMSOL Multiphysics. Then yeast cell was chosen to test the performance of the chips. The chip without fluid guides captured ~1.44 × 10⁵ cells and the capture efficiency was up to 71 %. And the chip with fluid guides captured ~5.0 × 10⁴ cells and the capture efficiency was ~25 %. The chip without fluid guides can capture more cells because the yeast cells in the chip without fluid guides are subject to larger hydrodynamic drag force.     

Characterization of in-vitro gel performance of novel MC with respect to the suitability for satiety applications

Rheological properties of aqueous solutions of a novel methyl cellulose has been compared to the performance of a conventional methyl cellulose. Gel formation of these materials is trigged only by increased temperatures. The low gelation temperature of the novel methyl cellulose enables this material to gel at body temperature. Compression measurements of the gels at various concentrations were performed and the investigated gel strength could be fitted according to an exponential equitation. The comparison to alginate as a known gel forming agent by acidification and known as satiety inducing agent showed comparable gel strength at 37 °C. Therefore, a potential of the novel methyl cellulose for human weight management applications has been identified. Gel formation in the human stomach could lead to a satiety effect.     

Pulmonary exposure to single-walled carbon nanotubes does not affect the early immune response against Toxoplasma gondii

ABSTRACT: BACKGROUND: Single-walled carbon nanotubes (SWCNT) trigger pronounced inflammation and fibrosis in the lungs of mice following administration via pharyngeal aspiration or inhalation. Human exposure to SWCNT in an occupational setting may occur in conjunction with infections and this could yield enhanced or suppressed responses to the offending agent. Here, we studied whether the sequential exposure to SWCNT via pharyngeal aspiration and infection of mice with the ubiquitous intracellular parasite Toxoplasma gondii would impact on the immune response of the host against the parasite. METHODS: C57BL/6 mice were pre-exposed by pharyngeal administration of SWCNT (80 + 80 mug/mouse) for two consecutive days followed by intravenous injection with either 1x103 or 1x104 green fluorescence protein and luciferase-expressing T. gondii tachyzoites. The dissemination of T. gondii was monitored by in vivo bioluminescence imaging in real time for 7 days and by plaque formation. The inflammatory response was analysed in bronchoalveolar lavage (BAL) fluid, and by assessment of morphological changes and immune responses in lung and spleen. RESULTS: There were no differences in parasite distribution between mice only inoculated with T. gondii or those mice pre-exposed for 2 days to SWCNT before parasite inoculum. Lung and spleen histology and inflammation markers in BAL fluid reflected the effects of SWCNT exposure and T. gondii injection, respectively. We also noted that CD11c positive dendritic cells but not F4/80 positive macrophages retained SWCNT in the lungs 9 days after pharyngeal aspiration. However, co-localization of T. gondii with CD11c or F4/80 positive cells could not be observed in lungs or spleen. Pre-exposure to SWCNT did not affect the splenocyte response to T. gondii. CONCLUSIONS: Taken together, our data indicate that pre-exposure to SWCNT does not enhance or suppress the early immune response to T. gondii in mice.     

Multi-layer compounds with integrated actor-sensor-functionality

A method is presented to integrate the cost and time consuming afterwards-joining technologies of piezo actors and sensors direct in the forming processes for metal blank structures. Possible applications for such parts are vibration/ noise damping, deformable shape control, energy harvesting or several sensor tasks. Different forming processes are experimentally investigated and the limits according to deformation of the brittle piezo components discussed. In the numerical research the piezomodule components (piezo fibre, electrodes and plastics embeddings) are homogenized to create a computation-time reducing simplified material model. In a back-transfer of global loads in the forming simulation a representative volume element (RVE) with cyclic boundary conditions is used to evaluate the loading of the piezoceramic material to describe the function degradation due to forming operation. The comparison of numerically and experimentally determined results in a linear manner lead to the necessarity of further numerical research. The location of maximum piezo-patch loading corresponds well with the numerical investigation. The numerical integral model for function degradation shows a large difference in comparison to the integral experimentally determined values. Therefore extensive experimental research direct on the piezomodule outside the forming compound is planned to fit the degradation model in a nonlinear manner.     

Influence of the phase diagram on the diffuse interface thickness and on the microstructure formation in a phase-field model for binary alloy

A phase-field model is used to investigate the responses of planar interfaces and of eutectic microstructures on the different shapes of the phase diagram in binary alloy systems. Numerical solutions of the dynamic field equations show that the interfacial profile and the thickness of the diffuse boundary layer depend on the segregation of the alloy components. The simulations are presented for different openings of binary phase diagrams. A strong influence of the phase diagram on the evolution of eutectic microstructures is found and quantitatively evaluated by defining an appropriate measure. The results are interpreted in terms of weighting the different contributions in the phase-field equation.     

Discrimination of vegetation strata in a multi-layered Mediterranean forest ecosystem using height and intensity information derived from airborne laser scanning

Height and intensity information derived from Airborne Laser Scanning (ALS) was used to obtain a quantitative vertical stratification of vegetation in a multi-layered Mediterranean ecosystem. A new methodology for the separation of different vegetation strata was implemented using supervised classification of a two-dimensional feature space spanned by ALS return height (terrain corrected) and intensity. The classification was carried out using Gaussian mixture models tuned on a control plot. The approach was validated using extensive field measurements from treated plots, ranging from single vegetation strata to a more complex multi-layered ecosystem. Plot-level canopy profiles derived from ALS and from a geometric reconstruction based on field measurements were in very good agreement, with correlation coefficients ranging from 0.73 (for complex, 3-layered) to 0.96 (simple, single-layered). In addition, it was possible to derive plot-level information on layer height, vertical extent and coverage with absolute accuracies of some decimetres (simple plots) to a meter (complex plots) for both height and vertical extent and about 10 to 15% for layer coverage. The approach was then used to derive maps of the layer height, vertical extent and percentage of ground cover for a larger area, and classification accuracy was evaluated on a per-pixel basis. The method performed best for single-layered plots or dominant layers on multi-layered plots, obtaining an overall accuracy of 80 to 90%. For subdominant layers in the more complex plots, accuracies obtained were as low as 48%.Our results demonstrate the possibility of deriving qualitative (presence and absence of specific vegetation layers) and quantitative, physical data (height, vertical extent and ground cover) describing the vertical structure of complex multi-layered forest ecosystems using ALS-based height and intensity information.