Experimental Investigations on the Thermal Diffusion Characteristics and Photoluminescence in Multiphase Micro Fluids Containing ZnO Micro Tubes and Fluorescein Dye

Optics and Spectroscopy - Scattering of light by disordered structures is normally detrimental to their applicability in many optoelectronic devices. However, some micro and nanostructures are...     

A novel hyperbranched polyester acrylate used for microfabrications

A novel hyperbranched polyester acrylate (HPEA) was synthesized based upon ethylenediamine tetraacetic acid as a “core” molecule, 5‐hydroxyisophthalic acid as an AB₂ monomer, and 2‐hydroxyethyl acrylate as an endcapping reagent. The obtained oligomer has an unsaturation concentration of 4.10 mmol_C?C g^?1 measured by nuclear magnetic resonance and a wide molecular weight distribution of 1.64 measured by gel permeation chromatography. The two‐photon absorption (TPA) photopolymerization of HPEA under the exposure of a Ti : sapphire femtosecond laser with a wavelength of 800 nm was investigated through laser exposure dose‐dependant spatial resolutions of its resins. The TPA photopolymerization thresholds at the range 1.6–4.3 × 10⁷ mJ cm^?2, and exposure dose windows at the range 3.4–4.3 for three formulations were determined. A spatial resolution of 0.85 μm was obtained through the TPA photopolymerization of the formulation containing 1 wt% photoinitiator and 0.3 wt% photoinhibitor. A diffraction grating and real three‐dimensional coupled gear wheel created by TPA photopolymerization were described to demonstrate the unique capability of HPEA in microfabrications. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis and shape memory behavior study of hyperbranched poly(urethane-tetrazole)

A novel hyperbranched poly(urethane-tetrazole)(HPUTZ) was synthesized via the A2+BB2' approach using hexadiisocyanate(HDI) and 3-(bis-(2-hydroxyethyl)) aminopropyltetrazole(HAPTZ).The molecular structure was characterized by FTIR and 1H NMR spectroscopy.The number average molecular weight was measured to be 1.05×104 g/mol with a polydispersity of 1.27 by GPC analysis.The HPUTZ was further cured by the semi-adduct(PEG-IPDI) from polyethylene glycol(PEG) reacting with isophorone diisocyanate(IPDI) to form th...     

Methods for solving fuzzy assignment problems and fuzzy travelling salesman problems with different membership functions

Mukherjee and Basu proposed a new method for solving fuzzy assignment problems. In this paper, some fuzzy assignment problems and fuzzy travelling salesman problems are chosen which cannot be solved by using the fore-mentioned method. Two new methods are proposed for solving such type of fuzzy assignment problems and fuzzy travelling salesman problems. The fuzzy assignment problems and fuzzy travelling salesman problems which can be solved by using the existing method, can also be solved by using the proposed methods. But, there exist certain fuzzy assignment problems and fuzzy travelling salesman problems which can be solved only by using the proposed methods. To illustrate the proposed methods, a fuzzy assignment problem and a fuzzy travelling salesman problem is solved. The proposed methods are easy to understand and apply to find optimal solution of fuzzy assignment problems and fuzzy travelling salesman problems occurring in real life situations.     

Photopolymerization of waterborne polyurethane acrylate dispersions based on hyperbranched aliphatic polyester and properties of the cured films

A series of novel waterborne hyperbranched polyurethane acrylates for aqueous dispersions (WHPUD) based on hydroxy-functionalized hyperbranched aliphatic polyester Boltorn H20 were investigated and used as UV curable oligomers. The aqueous dispersions were electrostatically stabilized with carboxyl groups incorporated into their structures, which were neutralized by triethylamine. The photopolymerization kinetics of these WHPUDs was studied with respect to polymerization rates and unsaturation conversions in the presence of a photoinitiator using differential scanning calorimetry. The polymerization rates of the resins under UV irradiation and the gel contents in the cured films showed an increasing trend with higher concentration of acrylate functionality, which is in favor of the theory of radical chain polymerization. The mechanical and thermal behaviors of UV cured films of aqueous dispersions were evaluated by tensile testing and dynamic mechanical thermal analysis (DMTA). The results of DMTA investigations indicated that the glass transition temperature shifted to higher temperature as the content of the hard segment consisting of IPDI-HEA increased. Moreover, the storage modulus and pendulum hardness also increased with increasing the hard segment content. As the degree of neutralization increased, the T_g and tensile strength decreased, whereas, the elongation at break increased.     

Sensitized luminescence of SrS:Dy,Cu,Cl phosphor

SrS:Dy,Cu,Cl phosphors for a fixed Dy concentration and different Cu concentrations were prepared by solid-state reaction. Studies on the structural and optical properties of the samples were carried out. From analysis of photoluminescence measurements, it was observed that the excitation in the absorption bands of Cu⁺ ion leads to transfer of energy to Dy³⁺ ion, thereby enhancing the intensity of its luminescence.     

A visual photothermal paper sensor for H_2S recognition through rational modulation LSPR wavelength of plasmonics

It is known that the localized surface plasmon resonance(LSPR) wavelength of plasmonics is highly dependent on compositions and geometry of plasmonics as well as the surrounding environments. Here, monodispersed Au@Ag core-shell nanoparticles(Au@Ag NPs) were prepared by carefully optimizing the shell thickness of Au@Ag NPs, and the presence of hydrogen sulfide(H_2 S) would significantly alter the LSPR wavelength. On the basis of this, a photothermal paper sensor for on-site recognition of H_2 S was constructed with a visual detection limit of 12.8 ng/L.     

Enhanced biocompatibility of ZnS:Mn quantum dots encapsulated with Aloe vera extract for therapeutic applications

Toxicity of nanoparticles remains to be a major issue in their application to the biomedical field. Aloe vera(AV) is one of the most widely exploited medicinal plants that have a multitude of amazing properties in the field of medicine.Methanol extract of Aloe vera can be used as a novel stabilising agent for quantum dots to reduce toxicity. We report the synthesis, structural characterization, antibacterial activity and cytotoxicity studies of ZnS:Mn quantum dots synthesized by the colloidal precipitation method, using methanol extract of Aloe vera(AVME) as the capping agent. The ZnS:Mn quantum dots capped with AVME exhibit superior performances in biocompatibility and antibacterial activity compared with ZnS:Mn quantum dots without encapsulation.