Fascinating Morphological Behavior of A2-star-(B-alt-C) Molecules in the Melts and Solutions

We employ dissipative particle dynamics (DPD) to examine the self-assembling behavior of A₂-star-(B-alt-C) molecules in the melt and solution states. When these molecules are in the melts, we successfully observe various types of hierarchical structure-within-structures, such as A-formed spheres in the matrix formed by B and C alternating layers, hexagonally packed A-formed cylinders in the matrix with B and C segregated layers, B and C alternating layers-within-lamellae, coaxial B and C alternating domains within hexagonally packed BC-formed cylinders, and concentric BC-alternating domains within BC-formed spheres, by increasing the A composition. These hierarchical structures by varying the composition are reported theoretically for the first time in the copolymer systems consisting of the alternating blocks, and in good agreement with the most recent experimental work by Matsushita and co-workers (Macromolecules 2007 , 40, 4023). Generally speaking, the small-length-scale B and C segregated domains are in parallel to the large-length-scale structures for the melt case. While when a selective solvent is added, we find that varying the solvent selectivity and the amount of solvent can induce the molecules to form quite different morphological patterns, such as the so-called segmented worm like micelles.     

Detection of picomolar levels of interleukin-8 in human saliva by SPR

Researchers at UCLA have discovered that the levels of interleukin-8 (IL-8) protein in the saliva of healthy individuals and patients with oropharyngeal squamous cell carcinoma (OSCC) are 30 pM and 86 pM, respectively. In this study, we present the development of the first immunoassay for the quantification of picomolar IL-8 concentrations in human saliva using Biacore surface plasmon resonance (SPR) in a microfluidic channel. A sandwich assay using two monoclonal antibodies, which recognize different epitopes on the antigen (IL-8), was used. Only 13 minutes were required to determine the quantity of pure IL-8 added to just 100 microL of either buffer or saliva-based samples. The limit of detection (LOD) of this immunoassay in buffer was 2.5 pM, and the precision of the response for each concentration was <3% of the coefficient of variation. When first analyzing the saliva supernatants, non-specific binding to the surface was observed. By adding carboxymethyl dextran sodium salt (10 mg mL(-1)) to compete with the surface dextran and primary antibody for non-specific interactions, the signal to noise ratio was greatly improved. The LOD of this immunoassay in saliva was 184 pM. A minimum concentration of 250 pM of exogenous IL-8 could then be consistently detected in a salivary environment. The precision of the response for each IL-8 concentration tested was <7% of the coefficient of variation. Diagnostic sensitivity for oral cancer can be achieved by pre-concentrating the saliva samples 10 fold prior to SPR analysis, making the target levels of IL-8 300 pM for healthy individuals and 860 pM for oral cancer patients.     

Solving Location-allocation Problems with Rectilinear Distances by Simulated Annealing

The objective of this study is to use the simulated annealing method to solve minisum location-allocation problems with rectilinear distances. The major advantage of the simulated annealing method is that it is a very general and efficient algorithm for solving combinatorial optimization problems with know objective functions. In this study, a simulated annealing algorithm was developed to solve the location-allocation problems, and its performance was compared with two other popular methods for solving location-allocation problems. The results show that simulated annealing is a good alternative to the two methods, as measured by both the solution quality and the computational time.     

Propagation loss, degradation and protective coating of long drawn microfibers

Propagation losses, transmission spectra and optical degradation attributed to surface scattering, crack propagation and water absorption were characterized for long microfibers fabricated by using a drawing tower. The propagation losses and optical degradation at 1550 nm wavelength were found increasing as the diameters decreased for the microfibers. A coating setup was established where polydimethylsiloxane (PDMS) was used as coating material and a CO₂ laser as curing source to form a cylindrical film layer along the surface of microfiber. It was confirmed that no optical degradation was observed for the long drawn microfibers with protective coating over a long period of 18 h.     

Properties of a gel polymer electrolyte based on lithium salt with poly(vinyl butyral)

Poly(vinyl butyral) (PVB) is of particular interest because of its low cost, extremely wide temperature work range (? 20 to 120 °C), and efficient chemical stability. In this study, a gel polymer electrolyte (GPE) containing Li⁺ ions was fabricated by using dimethylacetylamine (DMA), lithium perchlorate (LiClO₄), and PVB. The experimental results indicated that a highly transparent GPE with a high ionic conductivity (σ) could be obtained by mixing glue (DMA with a PVB content of 10 wt%) with a LiClO₄ content of 6 wt%. It was found that the ionic conductivity (σ) of the GPE depended on the LiClO₄ content, and the GPE with a LiClO₄ content of 6 wt% exhibited a maximum σ of 7.73 mS cm^?1, a viscosity coefficient of 3360 mPa s, and a transmittance greater than 89% (visible region) at room temperature. Furthermore, PVB improved the electrolyte solution leakage, and the LiClO₄ was used as an ion supply source for the high σ of the GPE.     

Sandwich nano-fin to reduce the aspect ratio requirement of metasurface

Optical Review - The current high-aspect-ratio Pancharatnam–Berry (PB)-phase metasurfaces in which vertical dimensions are much larger than the lateral dimensions are challenging to...     

The miniature light-field camera with high spatial resolution

Optical Review - A light-field camera is an optical system that provides multi-field-angle information in one shot. The microlens array (MLA) in a light-field camera system is the key to provide...