TecoflexTM functionalization by curdlan and its effect on protein adsorption and bacterial and tissue cell adhesion

Curdlan modified polyurethane was created by physically entrapping the former on TecoflexTM surface. ATR-FT-IR, SEM-EDAX and AFM analysis revealed the formation of stable thin curdlan layer on the film. Contact-angle measurements showed that the modified film was highly hydrophilic. Confocal laser scanning microscopy showed the existence of entrapped layer of approximately 20–25 μm in depth. Surface entrapment of curdlan minimized both protein adsorption and mouse L929 fibroblast cell adhesion relative to the control. Surface induced cellular inflammatory response was determined from the expression levels of proinflammatory cytokine TNF-α, by measuring their mRNA profiles in the cells using real time polymerase chain reaction (RT-PCR) normalized to the housekeeping gene GAPDH. The inflammatory response was suppressed on the modified substrate as expression of TNF-α mRNA was found to be up regulated on TecoflexTM, while it was significantly lower on curdlan substrate. The adhesion of S. aureus decreased by 62% on curdlan modified surface. Using such simple surface entrapment process, it will be possible to develop well-defined surface modifications that promote specific cell interactions and perhaps better performance in the long-term as implant.     

Human precision of operating a digitizing board: implications for electrocardiogram measurements

To investigate the precision achieved by human measurement on a digitizing board, 100 healthy volunteers (46 women, mean age 36 +/- 12 years) were asked to measure 15 times on artificial pattern composed of 15 points. A high precision digitizing board (programmed to the technical accuracy of +/- 50 microns) was used, and mean and maximum errors in measuring the same distance repeatedly and relocalizing the same point repeatedly were obtained for each volunteer. A median mean and maximum error of 0.2 mm and 1.0 mm were found for repeated distance measurement. When simulating QT dispersion measurement (measuring the same distance 12 times), median value of 20 ms was obtained for ECGs of 25 mm/s paper speed. The study concludes that human precision of operating a digitizing board is rather poor. A recommendation is given to use either a computer screen for manual measurement of ECGs or to provide an operator of the digitizing board with an immediate feedback of the precision and measurement stability achieved so that erroneous measurement can be actively rejected.     

Influence of helix bending deflection on the load transfer mechanism of screw piles in sand: Experimental and numerical investigations

This study investigates the load transfer mechanism that includes the effect of helix bending deflection on end-bearing capacity, distribution of ground pressure under the helix and soil deformation around the screw pile. The helix to shaft diameter ratio of 2.5 and 2.8 with a strong helix and a weak helix were used. The model ground was prepared with fine sand at 80% of relative density. To investigate the load transfer mechanism, the experimental tests were modelled in a 3D finite element code. A good agreement between the experimental and numerical approaches was found. The numerical analyses showed that large influence zone exists under screw pile with strong helix, which resulted in higher mobilized soil shear strength that contributed to higher end-bearing capacity. In the case of strong helix, uniform pattern of pressure distribution was observed under the central shaft and the helix. Similar pattern of pressure distribution under the central shaft was observed in weak helix case but the pattern of pressure distribution under the helix changed from uniform to triangular to trapezoidal at various stages during the load test. The normalized end-bearing capacity decreased linearly with the increase in normalized helix bending deflection in both approaches, i.e. experimental and numerical.     

Pollen diversity and its implications to the systematics of mimosaceous species by LM and SEM

In this study we have discussed pollen morphology of 14 mimosaceous species belonging to five genera by using light microscopy (LM) and scanning electron microscopy (SEM). The palynological features of species were determined by both qualitative and quantitative characters. The qualitative characters include pollen shape, colpi arrangement, and exine sculpturing. Oblate spheroidal shaped pollens were noted in Albizia procera, Albizia lebbeck, Acacia tortilis, Acacia ampliceps, and Acacia modesta, subprolate shaped pollen in Leucaena leucocephala, Prosopis julifera, and Acacia nilotica, prolate pollen in Acacia farnesiana and Prosopis glandulosa while spheroidal, sub spheroidal and sub oblate pollen grains were observed in Acacia catechu, Mimosa himalayana, Prosopis cineraria, respectively. Sparsely foveolate, reticulate, scabrate, and scrobiclate exine sculpturing were observed. Colpi with sunken ornamentation were seen in P. cineraria, P. glandulosa, P. juliflora, and L. leucocephala while colpi were absent in rest of the studied species. The quantitative characters were statistically studied using SPSS software. The current study gives important morpho‐palynological characters for identifying and validation of close related and similar taxa which will aid to the phylogenetic analysis of Mimosaceae family.     

A review of thermal rectification in solid-state devices

Thermal rectification, or the asymmetric transport of heat along a structure, has recently been investigated as a potential solution to the thermal management issues that accompany the miniaturization of electronic devices. Applications of this concept in thermal logic circuits analogous to existing electronics-based processor logic have also been proposed. This review highlights some of the techniques that have been recently investigated for their potential to induce asymmetric thermal conductivity in solid-state structures that are composed of materials of interest to the electronics industry. These rectification approaches are compared in terms of their quantitative performance, as well as the range of practical applications that they would be best suited to. Techniques applicable to a range of length scales, from the continuum regime to quantum dots, are discussed, and where available, experimental findings that build upon numerical simulations or analytical predictions are also highlighted.     

Dual band frequency tunable planar inverted‐F antenna for mobile handheld devices

A single feed, dual‐band frequency tunable planar inverted‐F antenna (PIFA) is presented for mobile handheld device applications. The proposed antenna is designed using the transmission line model. The dual‐band frequency tunability is achieved by varying the capacitance of the varactor diode between 4.15 pF (0 V) and 0.72 pF (15 V). The measured impedance bandwidth of ?6 dB is realized from 0.8 to 0.98 GHz for the lower band and 1.65 to 2.2 GHz for the higher band. The designed antenna provides the independent frequency tunability for both the bands without disturbing each other. The maximum antenna gain is estimated 2.64 dBi for the proposed PIFA. Also, it has a maximum efficiency of ~85% for the mobile handheld device. In addition, the proposed PIFA is investigated with SAM phantom model for head and hand, found to be within the acceptable SAR limit of 1.6 W/Kg.