Optical Non‐Linearity from Montmorillonite Intercalated with a Chromophore‐Containing Dendritic Structure: A Self‐Assembly Approach

Chromophore‐containing dendritic structures (G1, G2) are utilized to intercalate layered silicates, which results in a large d‐spacing up to 126 Å. An exfoliated morphology is obtained by mixing the dendritic structure intercalated layered silicates with polyimide in N,N‐dimethylacetamide solution. The dendritic structures attached on the clay template would arrange in a non‐centrosymmetric manner. This self‐assembled arrangement brought about the electro‐optical coefficients of 5–6 pm · V⁻¹ for these relatively low chromophore‐containing organic/inorganic nanocomposites without resorting to poling. Excellent temporal stability (100 °C) is also achieved.

     

Abstract Riccati equations in an L1 space of finite measure and applications to transport theory

We consider operator-valued Riccati initial-value problems of the form R′(t) + TR(t) + R(t)T = TA(t) + TB(t)R(t) + R(t)TC(t) + R(t)TD(t)R(t), R(0) = R₀. Here A to D and R₀ have values as non-negative bounded linear operators in L¹ (μ), where μ is a finite measure, and T is a closed non-negative operator in L¹ (μ) satisfying additional technical conditions. For such problems the notion of strongly mild solutions is defined, and local existence and uniqueness theorems for such solutions are established. The results of the analysis are applied to the reflection kernels with both isotropically scattering homogeneous and anisotropically scattering inhomogeneous medium.     

Growth and properties of GaSb, Ga1-xInxSb and Ga1-xAlxSb epilayers by MOCVD

GaSb-based compound semiconductors are suitable materials for low-noise avalanche photo-diodes(APD's) and long wavelength laser diodes and photodetectors. In this paper, we review the metal organic chemical vapor deposition (MOCVD) growth conditions and the properties of GaSb, GaInSb and AlGaSb epitaxial layers, including the effects of III/V ratio, growth temperature, pressure and growth rate on electrical quality, optical properties, surface morphology and solid distribution coefficients.     

Nonlinear dynamics of self-pulsating laser diodes under external drive

A self-pulsating laser diode under external drive shows the nonlinear dynamical effects of two competing frequencies. One can establish a route to chaos by increasing the modulation current. However, when the modulation frequency is varied, the chaotic state is suddenly destroyed at the harmonic frequencies of the self-pulsating frequency. This approach therefore offers a simple chaotic light source for possible optical chaotic communication.     

Structural studies of Na-montmorillonite exchanged with Fe2+, Cr3+, and Ti4+ by N2 adsorption and EXAFS

The structures of Fe(2+)-, Cr(3+)-, and Ti(4+)-modified montmorillonite prepared from ion exchange of the Na-clay with Fe(2+), Cr(3+), and Ti(4+) were investigated. Conventional BET surface area and spectroscopic analysis by extended adsorption fine structure (EXAFS) were applied. It was shown that the BET surface area of Na-clay was similar to that of Fe-clay, but somewhat different from those of Cr- and Ti-clay; it decreased in the order Na- > Fe- > Ti- > Cr-montmorillonite. This sequence appeared to be consistent with the ion size Na(+) (0.95 nm)>Fe(2+) (0.65 nm)>Cr(3+) (0.62 nm), except for Ti(4+) (0.69 nm). EXAFS data showed that some Si atoms within montmorillonite were replaced by Ti atoms and that a neostructure of titanium oxide was formed.     

White light emitting diodes (LEDs) with good color rendering indices (CRI) and high luminous efficiencies by the encapsulation of mixed and double-deck phosphors

In this paper, white light emitting diodes (LEDs) with good color rendering indices (CRI) and high luminous efficiencies have been fabricated by the encapsulation of mixed and double-deck phosphors. Experimental results revealed that white LEDs with the encapsulation of double-deck phosphors exhibited better CRI and higher luminous efficiencies than those with the encapsulation of mixed phosphors because no secondary excitation took place. The hue, CRI, and luminous efficiencies of white LEDs with double-deck phosphors under 200 mA were CIE_x,y = (0.357, 0.348), 90, and 62.3 lm/W, respectively while the hue, CRI, and luminous efficiencies of white LEDs with mixed phosphors under 200 mA were CIE_x,y = (0.366, 0.354), 89, and 56.5 lm/W, respectively.     

Conductive carbon tape as a sample platform for microwave-based MALDI MS detection of proteins and phosphoproteins

In this study, we developed a novel microwave-assisted protein preparation and digestion method for matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry analysis and identification of proteins that involves using conductive carbon tape as a sample platform for sample preparation (reduction and alkylation) and digestion under microwave heating and as a plate for MALDI analysis. This method allows for the enzymatic digestion products of proteins to be directly analyzed by MALDI mass spectrometry and results in a marked reduction in sample loss. Our protocol requires only a small volume (1 μL) of reaction solvent, which increases the frequency of enzyme-to-protein contact, thereby resulting in more efficient digestion of sample than conventional in-solution digestion methods. To test this protocol, we used magnetic iron (II, III) oxide nanoparticles as concentrating probes to enrich phosphopeptides from a mixture of peptides in enzymatically digested protein samples. We found that the one-pot on-tape-based protein preparation and digestion under microwave heating combined with the on-tape-based enrichment method not only dramatically reduced the time required for phosphopeptides analysis but also allowed for the simultaneous identification of phosphoproteins. The advantages of our protocol include ease of use, high digestion efficiency, high specificity, and rapid (15 min) identification of proteins and enrichment of phosphopeptides in a mixture of enzymatically digested protein samples.     

MEMS microwell and microcolumn arrays: novel methods for high-throughput cell-based assays

Although the cell-based assay is becoming more popular for high throughput drug screening and the functional characterization of disease-associated genes, most researchers in these areas do not use it because it is a complex and expensive process. We wanted to create a simple method of performing an on-chip cell-based assay. To do this, we used micro-electro-mechanical systems (MEMS) to fabricate a microwell array chip comprised of a glass substrate covered with a photoresist film patterned to form multiple microwells and tested it in two reverse transfection experiments, an exogenous gene expression study and an endogenous gene knockdown study. It was used effectively in both. Then, using the same MEMS technology, we fabricated a complementary microcolumn array to be used as a drug carrier device to topically apply drugs to cells cultured in the microwell array. We tested the effectiveness of microwell-microcolumn on-chip cell-based assay by using it in experiments to identify epidermal growth factor receptor (EGFR) activity inhibitors, for which it was found to provide effective high throughput and high content functional screening. In conclusion, this new method of cell-based screening proved to be a simple and efficient method of characterizing gene function and discovering drug leads.     

Magnetic iron oxide nanoparticle enrichment of phosphopeptides on a radiate microstructure MALDI chip

Several methods can be used to improve the enrichment of phosphorylated proteins. In this paper, phosphopeptides were enriched using magnetic iron(II,III) oxide (magnetite, Fe(3)O(4)) nanoparticles (NPs) on a radiate microstructure silicon chip and then analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) without further purification processes. We have developed a radiate microstructure chip on which samples can be concentrated for analysis by MALDI-TOFMS. The phosphoprotein digests and magnetic iron oxide NPs aqueous solution were deposited onto the central zone of the radiate microstructure silicon chip and enabled the on-chip enrichment of phosphopeptides. Microscopic analysis confirmed that the applied samples were confined to the central zone. Sample spots focused on the chip were much smaller than those on an unmodified plate with the same total volume. Different additives were used and optimized processes were performed to minimize non-phosphopeptides interference. These data collectively demonstrate that our on-chip phosphopeptide enrichment protocol is a rapid and easy-to-use method for phosphoproteome analysis.