Fabrication of a gradient refractive index preform using laminar shear mixing

A gradient refractive index rod was successfully prepared by a new fabrication method using laminar shear mixing, and a graded index polymer optical fiber that satisfied IEEE1394b was obtained from the method. To fabricate the gradient refractive index rod, a liquid monomer mixture with a relatively low refractive index was placed in a prepared cylindrical glass reactor and a transparent polymer rod with a higher refractive index was introduced at the center of the reactor. The reactor and the polymer rod were then rotated concurrently with a small rotating speed difference to generate a Couette flow in the liquid phase. The centrifugal force generated by rotation and the polymer diffusion into the liquid monomer mixture developed a graded concentration profile in a radial direction. The Couette flow could reduce the concentration fluctuation in a tangential direction. In addition, the graded index profile could be controlled by the copolymer composition of the rod and its diameter. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1100–1104, 2005     

Surface diffusion in microporous media

The surface diffusion of He, Ne, H₂, Ar, O₂, N₂ and CO₂ through Vycor microporous glass was analyzed theoretically and experimentally in the low pressure range as a function of temperature. A statistical-mechanical treatment was carried out in terms of partition functions to derive a general equation of surface flow. It was possible to separate the surface diffusion from the total flow using a simplified working equation. The conventional method which assumes that there is no adsorbed flow for helium should be discarded, because the fraction of surface diffusion for helium ranges from 0.133 to 0.247. It is also illustrated how to predict the permeability of a new gas for the same porous medium.     

Energetic surface heterogeneity of nanocrystalline TiO<Subscript>2</Subscript> films for dye-sensitized solar cells

Dye sensitized solar cells (DSSCs) have been receiving significant attention because they have many advantages compared to conventional organic solar cells. It has been known that the photovoltaic characteristics of DSSC are highly dependent on the adsorption properties of dyes on TiO₂ films. To analyze the surface heterogeneity of TiO₂ surfaces, single-phase anatase nanocrystallite titanium films were prepared by sol-gel method using the hydrolysis reaction of titanium tetraisopropoxide under acidic condition and characterized by XRD, FE-SEM and BET analysis. The adsorption energy distribution functions were calculated by the generalized nonlinear regularization method. It was found that the shape and the intensity of the adsorption energy distribution curve determined were highly related with the physical properties (i.e., geometrical heterogeneity) and chemical characteristics (i.e., energetic heterogeneity) of nanocrystalline TiO₂ for DSSC.     

An EGF-pseudomonas exotoxin A recombinant protein with a deletion in toxin binding domain specifically kills EGF receptor bearing cells

We constructed two chimeric toxins; one composed of epidermalgrowth factor (EGF) and pseudomonas exotoxin A (PE), designatedEGF-PE and the other composed of EGF and PE with a deletionof the Ia domain (cell-binding domain), designated EGF-PE (Ia).Both chimeric toxins reacted with anti-EGF and anti-PE antibodies.The cell-killing experiments showed that EGF-PE, but not EGF-PE(Ia),was cytotoxic to the murine fibroblast cell line NR6, whichcarried the PE receptor, but not the EGF receptor. However,after NR6 was transfected with DNA for the expression of humanEGF receptor, the transfected cell line, designated NRHER5,overexpressed human EGF receptors and became sensitive to EGF-PE(IA).The cytotoxicity of EGF-PE(Ia), but not EGF-PE, to NRHER5 canbe completely blocked by an excess amount of EGF. To completelyreverse the cytotoxicity of EGF-PE on NRHER5, both the EGF receptorpathway and the PE receptor pathway need to be blocked. Theseresults suggest that EGF-PE exhibits both EGF and PE bindingactivities, while EGF-PE(IA) possesses only EGF binding activity.Thus, EGF-PE(Ia) may be a better chimeric toxin than EGF-PEin terms of target specificity to EGF receptor bearing cells.We, therefore, examined the cytotoxicity of EGF-PE(Ia) to varioushuman cancer cell lines. We find that human cancer cells containingmore EGF receptors are more sensitive to EGF-PE(Ia).     

Investigation into etching mechanism of polyethylene terephthalate (PET) films treated in helium and oxygenated‐helium atmospheric plasmas

This research makes an investigation into the etching mechanism of atmospheric plasma conditions on the surface of polyethylene terephthalate (PET) films. Two types of untreated PET films (S/200 and S/500) were exposed to plasma for 0 to 5.0 min in 30‐s increments. The first set of each film type was treated in helium plasma, while the second was treated in oxygenated‐helium plasma. Differential Scanning Calorimetry (DSC) was used to characterize pre‐ and post‐exposure films. Weight changes and the degree of solubility were also determined. Based on peak area results, the percent crystallinity of PET S/200 increased by an average of 4.57% (helium treated) and 13.56% (oxygenated‐helium treated), while the S/500 showed only a small increase. There was no significant change in the melting or crystallization temperatures of either film type, indicating a decrease in amorphous content versus an increase in crystalline material. Weight loss analysis supports this theory. Solubility testing revealed a continual decrease in swelling as exposure time was increased. A model was developed to predict the change in the degree of solubility for polyphase surfaces considering the etching rate per phase. The model was applied to PET with good correlation between the model and experimental data. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2383–2389, 2004     

Companion robots for older adults: Rodgers’ evolutionary concept analysis approach

Intelligent Service Robotics - This study aims to analyze the concept of companion robots for older adults from the perspective of nursing. This study employed a concept analysis. The literature...     

A computational approach to characterize formation of a passivation layer in lithium metal anodes

Li metal anode is the “Holy Grail” material of advanced Lithium-ion-batteries (LIBs). However, it is plagued by uncontrollable dendrite growth resulting in poor cycling efficiency and short-circuiting of batteries. This has spurred a plethora of research to understand the underlying mechanism of dendrite formation. While experimental studies suggest that there are complex physical and chemical interactions between heterogeneous solid-electrolyte interphase (SEI) and dendrite growth, most of the studies do not reveal the mechanisms triggering these interactions. To deal with this knowledge gap, we propose a multiscale modeling framework which couples kinetic Monte Carlo and Molecular Dynamics simulations. Specifically, the model has been developed to account for (a) heterogeneous SEI, (b) dendrite-SEI interactions, and (c) effect of electrolyte on Li electrodeposition and potential dendrite formation. This allows the proposed computational model to be extended to various electrolytes and SEI species and generate results consistent with previous experimental studies.     

Antioxidant Activity of Osage Orange Extract in Soybean Oil and Fish Oil during Storage

The food industry is seeking natural antioxidants for edible oils that have comparable activity to synthetic counterparts. In this study, Osage orange extract (OOE) rich in osajin (42.9%) and pomiferin (30.0%) was obtained after hexane extraction of the fruit, and its antioxidant activity was examined in stripped soybean oil (SBO) and fish oil (FO), in which antioxidants and polar compounds were removed. The antioxidant activity of OOE was compared with commercial natural antioxidants (i.e., rosemary extract and mixed tocopherols) and a synthetic antioxidant, butylated hydroxytoluene (BHT), during storage at 25 and 40 °C. The 0.1% OOE had stronger antioxidant activity than 0.1% rosemary extract and 0.1% mixed tocopherols in both oils at 25 and 40 °C. Its activity was similar to 0.02% BHT in SBO and was similar or slightly stronger than 0.02% BHT in FO. When OOE was studied at 0.05, 0.1, and 0.2%, there was a weak dose–response in SBO but a stronger dose–response in FO. Headspace volatile analysis using solid phase micro-extraction (SPME) combined with GC–MS indicated that 0.1% OOE was very effective in preventing the formation of volatile oxidation products in both oils. Although it should be further tested for safety before the actual use, this study shows that OOE can be developed as an antioxidant for edible oils.     

A review on microwell and microfluidic geometric array fabrication techniques and its potential applications in cellular studies

The ability to trap precise quantities of cells or particles into confined areas has numerous applications for biological purposes. In particular, single cell trapping has received considerable attention because it permits the study of heterogeneity in a population, while trapping larger groups of cells have been used to form aggregates. Among several methods, the use of microwell offers a simple platform to capture cells or particles using hydrodynamic forces. This review examines the use of microwells in both static and microfluidic environments, and the application of microfluidic geometric arrays for trapping. This paper discusses the design and fabrication methods of microwells and compares the trapping and release techniques used in both static and microfluidics‐integrated microwells. Finally, we will summarize novel microfluidic geometric arrays used to capture cells or particles through hydrodynamic trapping.     

Effect of ZrO<Subscript>2</Subscript> coating on<Emphasis Type="Italic">in vitro</Emphasis> formation of calcium phosphate

We prepared zirconia thin films on (100) Si wafer by using a chemical solution deposition with a zirconium naphthenate as a starting material. The films were pyrolyzed at 500°C for 10 min and finally annealed for 30 min in air at 500°C. Amorphous films after annealing had no distinct structure and were uniform along the cross section line.In vitro formation of the calcium phosphate was evaluated by the field emission-scanning electron microscope, energy dispersive X-ray spectrometer and Fourier transform infrared spectroscopy.