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In closed kitchens, adequate ventilation is necessary. The kitchen range hood is a particularly essential equipment, and its efficacy depends on its exhaust volume. One of the simplest methods for increasing the exhaust volume is fan speed acceleration, but this increases energy consumption. Therefore, this study focuses on identifying a method for increasing the exhaust volume in a fan and simulating the exhaust of a range hood before and after implementing improvements under the same conditions to evaluate the distribution of harmful gases in a kitchen. The computational fluid dynamics method is applied to a range hood. First, to compare the simulation and experimental values of a range hood, the simulation values were calculated to have a certain degree of accuracy. Next, the verification process comprised of three parts for implementing improvements. The first part involved improving the top of the hood cover to enable smoother discharge of the gas. The second part consisted of improving the bottom of the hood cover moderate the reflux effect of gas flow into the range hood. The third part comprised a simulation of the range hood discharge effect after improvements were made as well as evaluation of the amount of harmful gases remaining in the kitchen.

High-entropy TaNbSiZrCr carbide coatings were deposited on WC substrates by radio-frequency unbalanced magnetron sputtering with C2H2 flow rates ranging from 0 to 23 sccm. The microstructure, mechanical properties, tribological properties and anti-corrosion resistance of the coatings were analyzed in both an as-sputtered condition and an annealed condition. The anti-glass sticking performance of the coatings was additionally investigated by annealing the coatings at 750 °C for 1 h on BK7 glass plates. The results showed that the as-sputtered and annealed coatings with a low carbon content (i.e., C2H2 flow rates lower than 8 sccm) had a high hardness (>34.1 GPa). The as-sputtered sample deposited with the maximum C2H2 flow rate (23 sccm) showed the best tribological properties of all the as-sputtered samples. However, the wear rate of the coating increased by a factor of around 10 times after annealing. The annealed coating nevertheless exhibited the highest corrosion resistance of all the coatings. Finally, the glass sticking results showed that the use of an appropriate C2H2 flow rate (4–12 sccm) was beneficial in enhancing the anti-glass-sticking performance of the coatings.

Photodynamic therapy (PDT) has been emerged as an alternative therapeutic modality in treatment of several malignant tumors. However, the therapeutic efficacy of PDT is often limited by the solubility of photosensitizers, tumor hypoxia and lack of target specificity to cancer cells. In this study, we developed a folate-conjugated fluorinated polymeric micelle (PFFA) to deliver the hydrophobic photosensitizer (chlorin e6, Ce6) to overcome these limitations. The fluorinated micelles exhibit the low critical micelle concentration, good long-term stability, higher oxygen-carrying capacity and better singlet oxygen generation efficiency compared to non-fluorinated micelles, indicating the potential to improve the PDT efficacy in hypoxic conditions. Cytotoxicity of PDT effect and cellular uptake demonstrate the higher cell growth inhibition to HeLa cells upon irradiation attributed to the selective internalization of Ce6-loaded PFFA micelles (PFFA-Ce6). All results demonstrate the PFFA-Ce6 micelles with targeting function and oxygen-carrying capacity can serve as a promising drug delivery system for hydrophobic photosensitizers and improvement on PDT efficacy.

Novel multifunctional fluorescent electrospun (ES) nanofibers exhibiting high sensitivity for various metal ions were prepared from binary blends of poly(2-hydroxyethyl methacrylate-co-N-methylolacrylamide) (poly(HEMA-co-NMA)) and 9,9-dihexylfluorene-2,7-bipyridine (bpy-F-bpy) by using a single-capillary spinneret. Different compositions of poly(HEMA-co-NMA) were synthesized through free-radical polymerization. The HEMA moieties were designed to exhibit hydrophilic properties, and the NMA content substantially affected the stability of the ES nanofibers in water. Experimental optical spectra and simulation results demonstrated that the fluorescent sensing probe bpy-polyfluorene-bpy could detect various metal ions. ES nanofibers prepared from copolymers with a 77:23 HEMA:NMA ratio blended with 5% bpy-F-bpy (P2–5) exhibited apparent color change from blue to green, color change from blue to blue-green and fluorescence quenching when detecting Zn2+, Hg2+ and Cu2+, respectively. The P2–5 ES nanofibers exhibited ultrasensitivity for Zn2+ (10−7–10−3 m) because of the 70 nm red shift of the emission maximum, and high reversibility because of their on–off switchable fluorescence emission upon the sequential addition of Zn2+ and ethylenediaminetetraacetic acid cycled several times. These results and a microfluidics system study indicated that the nanofibers, which have a high surface-to-volume ratio, can be used as ‘naked eye’ sensors for sensing various metal ions and as efficient multifunctional chemosensor-filtering devices. The chemosensor-filter based on novel multifunctional fluorescent electrospun (ES) nanofibers exhibiting high sensitivity for various metal ions were prepared from binary blends poly(HEMA-co-NMA) and bpy-F-bpy by using a single-capillary spinneret. It shows apparent color change from blue (blank) to green, to blue-green and to be fluorescence quenching when detecting Zn2+, Hg2+ and Cu2+, respectively, and high reversibility. A microfluidics system study indicated that these nanofibers can be used as ‘naked eye’ sensors for sensing various metal ions and as efficient multifunctional chemosensor-filtering devices.

Three random copolymers comprised pendant styrene and 4-(1-pyrenyl)-styrene (PyS) moieties in different molar ratios (21.4:1 (P1), 3.9:1 (P2), and 1.4:1 (P3)) were synthesized and employed as charge storage polymeric electret for nonvolatile organic field-effect transistor (OFET) memory application. The impact of varying the molar ratio in side-chain electron-donating pyrene moieties on the thermal, optical, photophysical, electrochemical, and electrical properties of the resulting pendant copolymers was evaluated to establish structure–property relationship. The OFET memory with P3 electret layer exhibits a largest memory window of 41.8 V, long retention time of 104 s with memory ratio of 105, and stable reversibility of at least 100 cycles due to enhanced field-induced holes trapping ability from higher PyS composition ratio. Therefore, polymer electret with pendant functional moieties shows potential for use as trapping layer in OFET memory devices. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015

A folic acid targeted mixed micelle system based on co-assembly of poly(e-caprolactone)-b-poly(methoxytri(ethylene glycol) methacrylate-co-N-(2-methacrylamido)ethyl folatic amide) and poly(e-caprolactone)-b-poly(diethylene glycol monomethyl ether methacrylate) is developed to encapsulate indocyanine green (ICG) for photothermal therapy and photodynamic therapy. In this study, the use of folic acid is not only for specific cancer cell recognition, but also in virtue of the carboxylic acid on folic acid to regulate the pH-dependent thermal phase transition of polymeric micelles for controlled drug release. The prepared ICG-loaded mixed micelles possess several superior properties such as a preferable thermoresponsive behavior, excellent storage stability, and good local hyperthermia and reactive oxygen species generation under near-infrared (NIR) irradiation. The photototoxicity induced by the ICG-loaded micelles has efficiently suppressed the growth of HeLa cells (folate receptor positive cells) under NIR irradiation compared to that of HT-29, which has low folate receptor expression. Hence, this new type of mixed micelles with excellent features could be a promising delivery system for controlled drug release, effective cancer cell targeting, and photoactivated therapy.

Multifunctional electrospun (ES) nanofibers prepared from random copolymers of poly{(N-isopropylacrylamide)-co-(stearyl acid)-co-[9,9-dihexylfluorene-2-bipyridine-7-(4-vinylphenyl)]} (poly(NIPAAm-co-SA-co-FBPY) were successfully prepared from the electrospinning technique with a single-capillary spinneret. FBPY demonstrated blue or red shift in emission wavelength and fluorescence quenching when chelating with different metal ions. With appropriate composition of SA in the copolymer, films and nanofibers could maintain their morphology in aqueous solution at different thermal treatments. Polymers in three states, solution, film and nanofiber, were prepared and their effects on sensing ability were investigated. The smooth nanofibers prepared from P2 (with copolymer composition of NIPAAm:SA:FBPY = 93:6:1) demonstrated superior sensitivity as low as 10−5 M in sensing zinc ions as compared to polymer films (10−3 M) due to the high specific surface area of nanofibers. The porous nanofibers of P2 were also manufactured to further enhance sensing performance and showed the best sensitivity (10−6 M) among three states when sensing with zinc ions (sensitivity of polymer solution in THF was about 10−5 M). These nanofibers also exhibit an interesting “on/off” switch behavior with decreasing temperature from 40 to 10 °C due to the hydrophobic–hydrophilic transition of NIPAAm moieties which cause the gradual swelling of nanofibers. These results indicated that the new nanofibers could have potential applications in multifunctional sensory devices.

Stimuli-responsive conjugated rod-coil block copolymers have received extensive attention recently because the stimuli-responsive coils, which undergo structure, shape, and property changes as triggered by external signals. They also take the advantages of conjugated rods, which provide tunable structural control and photophysical properties due to their π–π interaction. This review focuses on the recent progress in stimuli-responsive conjugated rod-coil block copolymers on their synthetic routes, stimuli-induced transitions in morphologies, and numerous applications in different fields. We first provide an overview on synthetic methods to prepare copolymers with two major architectures: linear and hyperbranched copolymers. Moreover, the effects of different stimuli on their morphological transitions and their corresponding photophysical properties are summarized. Finally, the promising applications of these block copolymers based on single or multiple stimuli-responsive systems are discussed and highlighted for “intelligent” sensory device and biomedical systems for theranostics.

We fabricated dual functional electrospun (ES) nanofibers by a coaxial electrospinning technique for enhancing the organic photovoltaic (OPV) device efficiency. The nanofibers contained poly[2,7-(9,9-dihexylfluorene)-alt-4,7-(2,1,3-benzothiadiazole)] (PFBT) nanoparticles as the luminescent solar concentrator (LSC) and Ag nanoparticles for the surface plasmon resonance (SPR) effect. Aligned- and crossed-fiber architecture patterns were fabricated to compare the effects of the architecture on the OPV efficiency. The plasmonic-enhanced LSC ES nanofibers with crosslinked poly(methacrylic acid) could be directly integrated into the conventional OPV configuration without sacrificing the coverage area of the active layer. In addition, the in situ reduction of Ag nanoparticles simultaneously enhanced the exciton generation of PFBT and the active materials with the SPR effect. The dual functional ES nanofibers with a crossed-pattern embedded into OPV devices provided significant light harvesting through down conversion and enhanced exciton generation. They led to PCE values of 4.11 and 7.12% for P3HT (poly(3-hexylthiophene)) : PC61BM ([6,6]-phenyl C61-butyric acid methyl ester) and PTB7 (polythieno[3,4-b]-thiophene-co-benzodithiophene) : PC71BM ([6,6]-phenyl C71-butyric acid methyl ester) ([6,6]-phenyl) photovoltaic cells, respectively, which are 18% enhancements compared to their parent devices. This interface-modification approach using plasmonic-enhanced LSC ES nanofibers provides a new approach for enhancing the OPV device performance.

In this study, we demonstrate a new series of fluorescent polymeric micelles self-assembled from two amphiphilic block copolymers, poly(ethylene glycol)-block-poly[styrene-co-[4-tri(9,9-dihexylfluoren-2,7-yl)styrene]] [PEG-b-P(S-co-TFS), P1] and poly(ethylene glycol)-block-poly[styrene-co-[4-(2-(4-benzo-[2,1,3]-thiadiazole)-9,9-dihexylfluoren-7-yl)styrene]] [PEG-b-P(S-co-BTFS), P2], with fluorescent moieties based on two different fluorene derivatives. The weight fraction and the chemical structure of these two fluorene derivatives could be correlated to the nanostructures and photophysical properties of the corresponding polymeric micelles. In particular, facile adjustment on the emission color of micelles enables the delicate design of drug carriers for the drug with specific photophysical properties. Two fluorescent drugs, curcumin (CUM) and doxorubicin (DOX), are chosen as model drugs for P1 and P2 micelles. Due to the spectral overlap between fluorescent micelles and drugs and their close proximity in the core of micelles, Forster resonance energy transfer (FRET) from micelles to drugs is observed for both the CUR-loaded P1-1 micelles and DOX-loaded P2-1 micelles, which could serve as an indication of successful encapsulation of drug in these micelles. Furthermore, the subsequent decrement of FRET resulting from the increasing distance between fluorene moieties and drugs could be used as an optical approach for monitoring the drug release from the drug carriers.

For this study, we prepared a new type of drug carrier with the characteristics of stimuli-responsive transition and tumor-specific recognition through the co-assembly of two series of amphiphilic block copolymers, poly(e-caprolactone)- b -poly[triethylene glycol methacrylate- co - N -methacryloyl caproic acid] and poly(e-caprolactone)- b -poly[triethylene glycol methacrylate- co - N -(2-(methacrylamido)ethyl) folatic amide]. The pH-dependent thermal transition and the content of the targeting ligands of the mixed polymeric micelles are well correlated with the chemical structures and compositions of these two copolymers. Doxorubicin-loaded mixed polymeric micelles are stable at body temperature in the neutral condition for prolonged circulation in blood vessels, and demonstrated rapid drug release at acidic pH levels. The cumulative drug release profiles showed a relatively slow release at pH 7.4, and a quick release of 85% in 3 h at pH 5.3. The cytotoxicity tests against FA-positive (HeLa) and FA-negative (HT-29) tumor cell lines suggest that this mixed polymeric micelle system has potential merits as a controlled and targeted drug delivery system.

A new type of fluorescent polymeric micelles is developed by self-assembly from a series of amphiphilic block copolymers, poly(ethylene glycol)-b-poly[styrene-co-(2-(1,2,3,4,5-pentaphenyl-1H-silol-1-yloxy)ethyl methacrylate)] [PEG-b-P(S-co-PPSEMA)]. Their capability of loading doxorubicin (DOX) is investigated by monitoring the loading content, encapsulation efficiency, and photophysical properties of micelles. Forster resonance energy transfer from PPSEMA to DOX is observed in DOX-loaded micelles, which can serve as an indication of successful encapsulation of DOX in these micelles. The application of this new type of fluorescent polymeric micelles as a fluorescent probe and an anticancer drug carrier simultaneously is explored by studying the intracellular uptake of DOX-loaded micelles.

A series of Cu2+-sensing nanofibers has been successfully prepared by electrospinning of poly[(N-isopropylacrylamide)-co-(N-hydroxymethyl acrylamide)-co-(4-rhodamine hydrazonomethyl-3-hydroxy-phenyl methacrylate)] [poly(NIPAAm-co-NMA-co-RHPMA), PNNR] random copolymers. These PNNR copolymers were synthesized by free radical copolymerization of three monomers, thermo-responsive NIPAAm, chemically crosslinkable NMA and Cu2+-sensing RHPMA, with the composition of RHPMA in the range of 2.4–16.3 wt%. In acidic environments, the PNNR copolymers showed highly selective and sensitive recognition and displayed “ON-OFF” fluorescence toward Cu2+ both in solution and in solid state (thin films and nanofibers). From the quantitative analysis via Stern-Volmer plots, PNNR nanofibers exhibited comparable Stern-Volmer constants as those of PNNR solutions in the order of 104 M−1, which are much higher than those of PNNR thin films. The enhanced sensitivity of PNNR electrospun nanofibers is attributed to their higher surface area compared to dip-coating films. The PNNR nanofibers also exhibited an on/off switchable sensing behavior in response to temperature change due to the hydrophilic-hydrophobic transition of PNIPAAm. In addition, the binding of PNNR with Cu2+ is chemically reversible both in solution and in nanofibers with the treatment of Na4EDTA.

In this study, we report the synthesis, properties, and electrical memory characteristics of new diblock copolymers, polystyrene-block-poly(styrene-pyrene) (PS-b-P(St-Py)), prepared by combining atom transfer radical polymerization and Suzuki coupling reaction. The effects of the St–Py block chain length on the electronic energy level, photophysical properties, and memory characteristics were explored. The PS42-b-P(St-Py)108 and PS66-b-P(St-Py)67 devices exhibited a dynamic random access memory characteristics with different turn-on threshold voltages of −2.7 and −3.1 V, respectively. Moreover, these memory devices showed a high ON/OFF current ratio of 109 and were electrically stable for at least 104 s in both ON and OFF states. However, the PS113-b-P(St-Py)45-based device displayed an insulating state in a low current variation of 10−12 to 10−14 A, which had a short St–Py block length. The mechanism of the switching behavior was explained by the charge hopping conduction between the pyrene units with coexisting charge-trapping environment. The volatility of the memory effect was depended on the ability of charge trapping/back transferring of trapped charge. The present study suggested that the electrical memory characteristics could be efficiently tuned through the block ratio between insulating segment and pendant-conjugated segment of the diblock polymers.

A series of new water-soluble cationic pyrene-dendron derivatives, G1, G2, and G3, was successfully synthesized and characterized. These new dendrons were designed with the quaternized amino moieties at the periphery of the dendrons for DNA detection and functionalized with pyrene as a fluorescent probe. The electrostatic interactions between the plasmid DNA (pDNA) and cationic charged dendrons in an aqueous solution resulted in a change in the photophysical properties of pyrene, which could be shown in the UV-vis and fluorescence spectra. Pyrene dendrons showed a high and rapid fluorescence response upon the addition of pDNA, which was strongly dependent on the size and hydrophobicity of the dendrons. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Three amphiphilic block copolymers are employed to form polymeric micelles and function as nanocarriers to disperse hydrophobic aggregation-induced emission (AIE) dyes, 1,1,2,3,4,5-hexaphenylsilole (HPS) and/or bis(4-(N-(1-naphthyl) phenylamino)-phenyl)fumaronitrile (NPAFN), into aqueous solution for biological studies. Compared to their virtually nonemissive properties in organic solutions, the fluorescence intensity of these AIE dyes has increased significantly due to the spatial confinement that restricts intramolecular rotation of these dyes and their better compatibility in the hydrophobic core of polymeric micelles. The effect of the chemical structure of micelle cores on the photophysical properties of AIE dyes are investigated, and the fluorescence resonance energy transfer (FRET) from the green-emitting donor (HPS) to the red-emitting acceptor (NPAFN) is explored by co-encapsulating this FRET pair in the same micelle core. The highest fluorescence quantum yield (62%) could be achieved by encapsulating HPS aggregates in the micelles. Efficient energy transfer (>99%) and high amplification of emission (as high as 8 times) from the NPAFN acceptor could also be achieved by spatially confining the HPS/NPAFN FRET pair in the hydrophobic core of polymeric micelles. These micelles could be successfully internalized into the RAW 264.7 cells to demonstrate high-quality fluorescent images and cell viability due to improved quantum yield and reduced cytotoxicity

A series of amphiphilic rod−coil diblock copolymers with a polyfluorene (PF) as a hydrophobic and light-emitting rod and a poly(N-isopropylacrylamide) (PNIPAAm) as a hydrophilic coil were prepared. Their micellar nanostructures and fluorescence properties were stimulated using solvents, e.g., water and tetrahydrofuran (THF)/toluene (1:10 by volume), which were characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM), and fluorescence spectroscopy. A typical block copolymer P2 (Mn = 14 400, Mw/Mn = 1.80, the PF weight fraction is 9.4%) in water exhibited micelles with the PNIPAAm block as the corona, whereas the polymer showed inverse micelles in mixed organic solvents of THF/toluene with PF as the corona. Such different nanostructures resulted in their different fluorescence properties. The fluorescence spectrum of P2 did not indicate aggregations of the PF chains in the THF/toluene mixture. Blue emission with a high quantum yield (0.80) was...

New donor–acceptor conjugated copolymers called poly}2,7-(9,9′-dihexylfluorene)-co-5,10-[pyrazino(2,3-g)quinoxaline]{s or PFPQs [where F represents the 2,7-(9,9′-dihexylfluorene) moiety and PQ represents the 5,10-(pyrazino[2,3-g]quinoxaline) moiety], synthesized by the palladium-catalyzed Suzuki coupling reaction, are reported. The PQ contents in the PFPQ copolymers were 0.3, 1, 5, and 50 mol %, and the resulting copolymers were named PFPQ0.3, PFPQ01, PFPQ05, and PFPQ50, respectively. Absorption spectra showed a progressive redshift as the PQ acceptor content increased. The relatively small optical band gap of 2.08 eV for PFPQ50 suggested strong intramolecular charge transfer (ICT) between the F and PQ moieties. The photoluminescence emission peaks of the PFPQ copolymer films also exhibited a large redshift with enhanced PQ contents, ranging from 551 nm for PFPQ0.3 to 592 nm for PFPQ50. However, the PFPQ copolymer based electroluminescence (EL) devices showed poor device performances probably due to the strong confinement of the electrons in the PQ moiety or significant ICT. This problem was resolved with a binary blend of poly[2,7-(9,9-dihexylfluorene)] (PF) and PFPQ with a volume ratio of 95/5 (BPQ05). Multiple emission peaks were observed at 421, 444, 480, 516, and 567 nm in the BPQ05-based EL devices because the low PQ content led to incomplete energy transfer. The Commission Internationale de L'Eclairage 1931 coordinates of the BPQ05-based EL device were (0.31, 0.32), which were very close to the standard white emission of (0.33, 0.33). Furthermore, the maximum luminescence intensity and luminescence yield were 524 cd/m2 and 0.33 cd/A, respectively. This study suggested that a pure white light emission was achieved with the PFPQ copolymers or PF/PFPQ blends through the control of the energy transfer between F and PQ. Such PFPQ copolymers or PF/PFPQ blends would be interesting for electronic and optoelectronic devices. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthesis and Properties of New Small Band Gap Conjugated Polymers: Methine Bridged Poly(3,4-ethylenedioxypyrrole)

The synthesis, morphology, and photophysical properties of PF-b-PAA with different coil lengths in dilute solutions of dichloromethane/methanol are reported. A tape-like lamellar morphology is observed at a short coil length of PF-b-PAA. As the coil length increases, a large compound micelle, sphere, or vesicle is observed with different methanol contents because of the enhancement of the PAA swelling with methanol and the interfacial tension between the PF core and the PAA corona. Upon further increase of the coil length, an inverted morphology of a sphere or rod with a PF corona and PAA core is first observed but the core/corona is then reversed at a high methanol content as a result of the enhanced solubility of PAA. The morphological transformation leads to a significant variation in optical absorption or fluorescence characteristics because of the possible H-aggregate formation.

The theoretical geometries and electronic properties of fluorene (F) based alternating donor–acceptor conjugated copolymers and their model compounds were studied by the density function theory (DFT) at the B3LYP level with 6–31G or 6–31G** basis set. The acceptors investigated in this study include thiazole (TZ), thiadiazole (TD), thienopyrazine (TP), thienothiadiazole (TT), thiadiazolothienopyrazine (TTP), quinoxaline (Q), benzothiadiazole (BT), pyrazinoquinoxaline (PQ), thiadiazoloquinoxaline (TQ), and benzobisthiathiadiazole (BB). The torsional angle, bridge bond length, bond length alternation, and intramolecular charge transfer were simulated and correlated with the electronic properties, i.e., HOMO, LUMO level, and band gap. The geometries of fluorene-based donor–acceptor alternating copolymers and their model compounds are significantly affected by the structure of acceptors, particularly the ring size on the backbone. The electronic properties of the polymers and their model compounds are well correlated with the acceptor strength, coplanarity of the backbone, and intramolecular charge transfer. The theoretical study suggests that the electronic properties of alternating fluorene–acceptor conjugated copolymers could be tuned by the geometries or acceptor strength. Hence, these proposed copolymers could have potential applications as light-emitting diodes (LEDs), transparent conductor, or photovoltaic devices.

A series of novel light-emitting copolymers consisted of 9,9-dihexylfluorene (F) and different acceptor segments, including quinoxaline (Q), 2,1,3-benzothiadiazole (BT) and thieno[3,4-b]-pyrazine (TP), were synthesized by the palladium-catalyzed Suzuki coupling reaction. Three fluorene-acceptor alternating copolymers (PFQ, PFBT, PFTP) and six F-TP (PFTP0.5–PFTP35) random copolymers were investigated and compared with the parent polyfluorene (PF). The experimental results suggest that the acceptor strength or content significantly affect the electronic and optoelectronic properties. The optical absorption maxima of the PF, PFQ, PFBT, and PFTP are 368, 416, 470, and 578 nm, respectively, which indicates the significance of intramolecular charge transfer. The electrochemical band gap also shows a similar trend. The incorporation of the acceptor into the PF lowers the LUMO level and thus could improve the electron-accepting ability of the PF. The emission maxima on the photoluminescence (PL) spectra of the PF, PFQ, PFBT, and PFTP films are 424, 493, 540, and 674 nm, which correspond to the color of blue, green, yellow, and red, respectively. It suggests that the full color of emission can be achieved by different acceptors. The significant positive solvatochromism on the PL spectra in different polar solvents suggests the efficient intramolecular charge transfer in PFTP. However, such charge transfer or heavy-atom effect results in fluorescence quenching and thus reduces the PL efficiencies. By random copolymerizing the TP into the PF, the PL efficiency could be improved. A significantly reduction on the PF emission peak with increasing the TP content suggests the energy transfer between the PF and TP segments. Besides, the characteristics on the electroluminescence (EL) devices of ITO/PEDOT:PSS/emissive layer/Ca/Ag suggest that such energy transfer results in the complete quenching of the PF emission at only 1% TP content in the PFTP01. The maximum external quantum efficiency (EQE) of the EL device based on the PFTP01 is superior to that of the PF due to the reduced LUMO level in matching with the Ca. The CIE 1931 coordinates of the PFTP01 based EL device under the condition of maximum EQE is (0.66, 0.31), which is close to the standard red of (0.66, 0.34) demanded by the National Television System Committee (NTSC). The luminescence characteristics based on the prepared polymers depend on the Forster energy transfer or the intramolecular charge transfer, or heavy-atom fluorescence quenching. The present study suggests that the tuning of the electronic and optoelectronic properties could be achieved by incorporating various acceptors or content into the polyfluorenes.

The photophysical and electroluminescent properties of fluorene-based polymer blend systems were studied, including blue-emitting poly[2,7-(9,9′-dihexylfluorene)] (PF), green-emitting poly[2,7-(9,9′-dihexylfluorene)-alt-5,8-quinoxaline] (PFQ), yellow-emitting poly[2,7-(9,9′-dihexylfluorene)-alt-4,7-(2,1,3-benzothiadiazole)] (PFBT), and red-emitting poly[2,7-(9,9′-dihexylfluorene)-alt-5,7-(thieno[3,4-b]pyrazine)] (PFTP). The binary polymer blends, based on PF blended with 5–25 wt % PFQ or PFBT, were studied to rationalize the effects of the chemical structures and compositions on the intermolecular energy transfer and quantum efficiency. A significant enhancement of quantum efficiency was observed by the blending of a relatively small amount of PFQ or PFBT. Ternary blends composed of PF, PFQ (or PFBT), and PFTP were also studied for potential white-light-emitting diodes (WLEDs). The precise composition control of the polymer blends resulted in incomplete Forster energy transfer and emissions from all the components simultaneously. White-emitting electroluminescence was achieved by the blending of PF with relatively small amounts of the PFQ (or PFBT) and PFTP. The luminance yield and maximum external quantum efficiency of the WLED with the ternary blend FBTTP1 (PF/PFBT/PFTP = 99.65:0.05:0.30 w/w/w) as the emissive layer were 1.89 cd/A and 0.47%, respectively. The electron-acceptor characteristics, Forster energy transfer, and emissive colors govern the design of WLEDs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 67–78, 2007

The commercial polysaccharides of alginic acid (medium (3500 cps, 2% solution) and low (250 cps, 2% solution) viscosities) were esterified with acidic methanol (1 mmol L−1 HCl) at 4 °C with gentle stirring for 5 days to obtain methyl esters of medium-viscosity alginic acid (ME-MVA) and low-viscosity alginic acid (ME-LVA). These ME-MVA and ME-LVA were reacted with alkaline hydroxylamine to obtain medium-viscosity alginic acid hydroxamates (MVA-NHOH) and LVA-NHOH. The percentages of hydroxamic acid content in MVA-NHOH and LVA-NHOH were calculated as 25% and 20%, respectively. The hydroxamate derivatives of alginic acid were used to test the antioxidant and semicarbazide-sensitive amine oxidase (SSAO) inhibitory activities in comparison with original materials (MVA and LVA). The half-inhibition concentrations, IC50, of scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) were 24.5 and 29.8 µg mL−1 for MVA-NHOH and LVA-NHOH, respectively. However, few scavenging activities of the MVA and LVA were found at the same concentrations. The IC50 of the positive control of butylated hydroxytoluene was 5 µg mL−1. The scavenging activity of DPPH radical was pH-dependent, and the optimal pH for both of MVA-NHOH and LVA-NHOH was the Tris-HCl buffer (pH 7.9). Using electron spin resonance (ESR) to detect the activity of scavenging hydroxyl radicals, both alginic acid hydroxamates showed dose-dependent scavenging activities, and the IC50 was 90 and 92 µg mL−1, respectively, for MVA-NHOH and LVA-NHOH. Both alginic acid hydroxamates also exhibited protection against hydroxyl radical-mediated DNA damage. Both MVA-NHOH and LVA-NHOH showed dose-dependent inhibitory activities against bovine SSAO (2.53 units); the IC50 was 0.16 and 0.09 µg mL−1, respectively, for MVA-NHOH and LVA-NHOH, compared with 3.81 µg mL−1 of semicarbazide (positive controls). Amine oxidase activity staining also revealed that both MVA-NHOH and LVA-NHOH exhibited SSAO inhibitory activities. Both MVA-NHOH and LVA-NHOH showed mixed non-competitive inhibition against bovine SSAO. It was found that the V′max value was reduced and the K′m value was either increased (added MVA-NHOH, 0.05 µg mL−1) or reduced (added LVA-NHOH, 0.11 µg mL−1) in the presence of alginic acid hydroxamate. Copyright © 2006 Society of Chemical Industry

A benchmark problem with air medium in a square cavity heated by a vertical side is studied in a Ra range near its critical value without using the usual model approximations, such as Boussinesq or low-Mach-number approximation. Two analysis methods of power spectrum and phase trajectory are adopted to distinguish the flow pattern in the cavity. It demonstrates how the flow evolves from transition to turbulent regimes with increasing Ra values.

A novel starlike polyfluorene derivative, PFO-SQ, was synthesized by the Ni(0)-catalyzed reaction of octa(2-(4-bromophenyl)ethyl)octasilsesquioxane (OBPE-SQ) and polydioctylfluoroene (PFO). The incorporation of the silsesquioxane core into polyfluorene could significantly reduce the aggregation as well as enhance the thermal stability. The DSC study showed an elimination of the glass transition and crystallization as well as a significant reduction of the melting enthalpy in PFO-SQ. The UV−vis absorption spectra in a different solvent combination or solid-state film showed an intensity reduction of the aggregation peak for PFO-SQ in comparison with that of PFO. The stability of the photoluminescence spectra of PFO-SQ could be up to 150 °C, while that of PFO showed a significant green emission at 530 nm. A single-layer LED device using PFO-SQ showed a turn on voltage of 6.0 V, a brightness of 5430 cd/m2 (at a drive voltage of 8.8 V), and a current density of 0.844 A/cm2. The maximum luminescence intensity ...

The pH responsibility of cationic charged dendrons, which were previously synthesized for DNA-sensing applications, was investigated. The first and second generation amide dendrons G1 and G2 formed...

Among the eight amino acid hydroxamates tested, Glycine hydroxamate (GH) was the best inhibitor of mushroom tyrosinase (TYR). With l-tyrosine as substrate, the GH inhibition of the monophenolase activity of the mushroom TYR was noncompetitive. GH decreased not only TYR protein expression, but also melanin content, tyrosinase-related protein (TRP)-1, TRP-2, and microphthalmia-associated transcription factor (MITF) expression in B16F10 melanoma cells while in the presence of α-melanocyte-stimulating hormone (α-MSH). GH also significantly decreased the isobutylmethylxanthine (IBMX)-induced increase in melanin content, which was not prevented by the ERK inhibitor PD98059. These results suggest GH has the potential for use in cosmetic hypopigmentation.

Polymeric micelles are promising carriers for anti-cancer agents due to their small size, ease of assembly, and versatility for functionalization. A current challenge in the use of polymeric micelles is the sensitive balance that must be achieved between stability during prolonged blood circulation and release of active drug at the tumor site. Stimuli-responsive materials provide a mechanism for triggered drug release in the acidic tumor and intracellular microenvironments. In this work, we synthesized a series of dual pH- and temperature-responsive block copolymers containing a poly(e-caprolactone) (PCL) hydrophobic block with a poly(triethylene glycol) block that were copolymerized with an amino acid-functionalized monomer. The block copolymers formed micellar structures in aqueous solutions. An optimized polymer that was functionalized with 6-aminocaproic acid (ACA) possessed pH-sensitive phase transitions at mildly acidic pH and body temperature. Doxorubicin-loaded micelles formed from these polymers were stable at blood pH (~7.4) and showed increased drug release at acidic pH. In addition, these micelles displayed more potent anti-cancer activity than free doxorubicin when tested in a tumor xenograft model in mice.

The DC and RF characteristics of Ga/sub 0.49/In/sub 0.51/P-In/sub 0.15/Ga/sub 0.85/As enhancement- mode pseudomorphic HEMTs (pHEMTs) are reported for the first time. The transistor has a gate length of 0.8 /spl mu/m and a gate width of 200 /spl mu/m. It is found that the device can be operated with gate voltage up to 1.6 V, which corresponds to a high drain-source current (I/sub DS/) of 340 mA/mm when the drain-source voltage (V/sub DS/) is 4.0 V. The measured maximum transconductance, current gain cut-off frequency, and maximum oscillation frequency are 255.2 mS/mm, 20.6 GHz, and 40 GHz, respectively. When this device is operated at 1.9 GHz under class-AB bias condition, a 14.7-dBm (148.6 mW/mm) saturated power with a power-added efficiency of 50% is achieved when the drain voltage is 3.5 V. The measured F/sub min/ is 0.74 dB under I/sub DS/=15 mA and V/sub DS/=2 V.

A new type of fluorescent polymeric micelles is developed by self-assembly from a series of amphiphilic block copolymers, poly(ethylene glycol)-b-poly[styrene-co-(2-(1,2,3,4,5-pentaphenyl-1H-silol-1-yloxy)ethyl methacrylate)] [PEG-b-P(S-co-PPSEMA)]. Their capability of loading doxorubicin (DOX) is investigated by monitoring the loading content, encapsulation efficiency, and photophysical properties of micelles. Förster resonance energy transfer from PPSEMA to DOX is observed in DOX-loaded micelles, which can serve as an indication of successful encapsulation of DOX in these micelles. The application of this new type of fluorescent polymeric micelles as a fluorescent probe and an anticancer drug carrier simultaneously is explored by studying the intracellular uptake of DOX-loaded micelles.

Background The impact of diuretic usage and dosage on the mortality of critically ill patients with acute kidney injury is still unclear. Methods and Results In this prospective, multicenter, observational study, 572 patients with postsurgical acute kidney injury receiving hemodialysis were recruited and followed daily. Thirty-day postdialysis mortality was analyzed using Cox's proportional hazards model with time-dependent covariates. The mean age of the 572 patients was 60.8±16.6 years. Patients with lower serum creatinine (p = 0.031) and blood lactate (p = 0.033) at ICU admission, lower predialysis urine output (p = 0.001) and PaO2/FiO2 (p = 0.039), as well as diabetes (p = 0.037) and heart failure (p = 0.049) were more likely to receive diuretics. A total of 280 (49.0%) patients died within 30 days after acute dialysis initiation. The analysis of 30-day postdialysis mortality by fitting propensity score-adjusted Cox's proportional hazards models with time-dependent covariates showed that higher 3-day accumulated diuretic doses after dialysis initiation (HR = 1.449, p = 0.021) could increase the hazard rate of death. Moreover, higher time-varying 3-day accumulative diuretic doses were associated with hypotension (p

Three amphiphilic block copolymers are employed to form polymeric micelles and function as nanocarriers to disperse hydrophobic aggregation-induced emission (AIE) dyes, 1,1,2,3,4,5-hexaphenylsilole (HPS) and/or bis(4-(N-(1-naphthyl) phenylamino)-phenyl)fumaronitrile (NPAFN), into aqueous solution for biological studies. Compared to their virtually nonemissive properties in organic solutions, the fluorescence intensity of these AIE dyes has increased significantly due to the spatial confinement that restricts intramolecular rotation of these dyes and their better compatibility in the hydrophobic core of polymeric micelles. The effect of the chemical structure of micelle cores on the photophysical properties of AIE dyes are investigated, and the fluorescence resonance energy transfer (FRET) from the green-emitting donor (HPS) to the red-emitting acceptor (NPAFN) is explored by co-encapsulating this FRET pair in the same micelle core. The highest fluorescence quantum yield (62%) could be achieved by encapsulating HPS aggregates in the micelles. Efficient energy transfer (>99%) and high amplification of emission (as high as 8 times) from the NPAFN acceptor could also be achieved by spatially confining the HPS/NPAFN FRET pair in the hydrophobic core of polymeric micelles. These micelles could be successfully internalized into the RAW 264.7 cells to demonstrate high-quality fluorescent images and cell viability due to improved quantum yield and reduced cytotoxicity

2,1,3-Benzothiadiazole (BTD)-containing red emitter was chemically conjugated onto amphiphilic poly(ethylene glycol)-block-poly(epsilon-caprolactone) (PEG-b-PCL) copolymers to form two new fluorophore-conjugated block copolymers (P5 and P7). P5 is a cationic amino group-containing polymer, whereas, P7 is a neutral polymer. The polymers formed micelles in aqueous solution with average diameters of 45 nm (P7) and 78 nm (P5), which were characterized using dynamic light scattering (DLS) and atomic force microscopy (AFM). Cell internalization of the micelles using mouse macrophage RAW 264.7 was investigated. The micelles formed from P5 were endocytosed into the cell's cytoplasm through a non-specific endocytosis process, which was affected by temperature and calcium ions. Micelles formed from P7 could not be endocytosed. The dramatic difference of cell uptake between P5 and P7 indicated the cationic amino groups had a strong influence on the cell internalization to enhance the endocytosis pathway. 3-(4,5-Dimethyl thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) viability assay was used to evaluate the cytotoxicity of the P5 micelle and no significant toxicity was observed. This study is the first report regarding the synthesis of BTD-conjugated block copolymers and the application of the biomacromolecules for bioimaging.

A hydrophobic two-photon absorbing (2PA) red emitter (R) was successfully incorporated into micelles formed from two block copolymers, poly(e-caprolactone)-block-poly(ethylene glycol)s, for imaging and toxicity studies. In micelles, the chromophore R exhibits a 2PA cross-section of 400 GM (1 GM = 1 × 10−50 cm4 s photon−1 molecule−1) at 820 nm, which is among the highest values reported for red 2PA emitters. The micelles with a cationic amino moiety-containing poly(ethylene glycol) corona showed an enhancement of cell internalization and delivered the dye into the cytoplasmic regions of the mouse macrophage RAW 264.7 cells. In comparison, the dye in micelles with neutral poly(ethylene glycol) as corona could not be delivered into the cells. Cytotoxicity of the micelle-R constructs was studied using a 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. More than 90% of the cells were viable after they were stained with the dye-containing micelles at different concentrations (dye concentrations of 2–6 μM and polymer concentrations of 0.05–0.15 mg/mL) for 16 h. This is the first reported application of a hydrophobic 2,1,3-benzothiadiazole-containing 2PA red emitter delivered into the cytoplasm of cells for bioimaging and toxicity assessment. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010

Rod-coil block copolymers are of unique and interesting characteristics since their physical properties can be reversibly tuned in response to the external stimuli, such as change in solvent quality. In this study, dissipative particle dynamics is used to investigate the surface structures of rod-coil polymer brushes tethered onto a surface. When immersed in the selective solvent for the coil blocks, rod blocks tend to form aggregates. Our results show that linear and Y-shaped polymer brushes exhibit similar aggregative behavior. However, some of the surface structures can be acquired within experimentally attainable surface grafting density only for Y-shaped polymer brushes. On the other hand, comblike polymer brushes are found to possess more diverse aggregative manners than linear brushes. Surface structures with aggregates taking the forms of cones, cylinders, or layers of spheres are found. By controlling the aggregative structures, it is possible for us to adjust the physical properties, such as optical function, of the material.

A combined theoretical and experimental investigation of conjugated rod-coil block copolymer brushes is reported. The theoretical study for the surface structures of rod-coil block copolymer brushes was established based on the simulation method of dissipative particle dynamics. The effects of solvent stimuli, grafting density, and rod-coil block ratio of the polymer brushes on the surface structures were examined. The rod blocks of polymer brushes were found to be well-dispersed on the surface in their good solvents. On the other hand, aggregative domains of the rod blocks were formed in their poor solvents with the conformations of isolated islands or worm-like structures depending on the grafting density of the polymer brushes. The aggregative domains tend to stay on top of the coil blocks for small rod-to-coil block ratio. However, the submergence of the aggregative domains into the coil blocks is thermodynamically preferred for large enough rod-to-coil block ratio. New multifunctional amphiphilic rod-coil block copolymers, poly-[2,7-(9,9-di-n-hexylfluorene)]-block-poly-[poly(ethylene glycol) methyl ether methacrylate]-block-poly-[3(tripropoxysilyl)propyl methacrylate] (PF-b-PPEGMA-b-PPOPS), with two different block ratios were synthesized and used to prepare the corresponding polymer brushes via the grafting- method. The effects of stimuli factors on the surface structures characterized by the atomic force microscopy images were consistent with the theoretical results. Furthermore, the photophysical properties of PF-b-PPEGMA-b-PPOPS brushes were significantly varied by the solvent stimuli. The emission peaks originated from the aggregation and/or excimer formation of PF blocks were observed after methanol treatment. The photoluminescence intensity and its efficiency were well correlated to the surface structure and the methanol content in mixed solvents. Our study demonstrates how the surface structures and photophysical properties of rod-coil block copolymer brushes response to environmental stimuli.

* BACKGROUND AND OBJECTIVE: To compare two kinds of cataract removal methods combined with pars plana vitrectomy and posterior chamber intraocular lens (PC-IOL) implantation. * PATIENTS AND METHODS: Cataract removal was performed by either phacoemulsification or extracapsular cataract extraction (ECCE) and followed by pars plana vitrectomy and PC-IOL implantation. Between May 1996 and June 2001, 31 and 22 patients with cataract and vitreoretinal disease were treated by phacoemulsification and ECCE, respectively, combined with pars plana vitrectomy and PC-IOL implantation. Preoperative demographic data and postoperative vision, astigmatism change, and complications were analyzed. * RESULTS: The mean age of patients in the phacoemulsification and ECCE groups was 62.5 and 63.4 years, respectively. Diabetes mellitus was the most common underlying disease resulting in vitreous opacity. Vision improved in 87.1% of the phacoemulsification group and 59.1% of the ECCE group. The change in astigmatism after surgery was 0.92 ± 1.08 D (P = .001) in the ECCE group and 0.25 ± 0.74 D (P = .087) in the phacoemulsification group. There were fewer postoperative complications, including recurrent vitreous hemorrhage, increased intraocular pressure, and iris changes in the phacoemulsification group than in the ECCE group. * CONCLUSION: Phacoemulsification and ECCE combined with pars plana vitrectomy and PC-IOL implantation are both effective surgical methods to achieve better and more rapid visual rehabilitation for patients with combined cataract and vitreoretinal disease. In this study, phacoemulsification combined with pars plana vitrectomy and PC-IOL implantation resulted in greater improvement in vision, less astigmatism change, and fewer postoperative complications. [Ophthalmic Surg Lasers Imaging 2005;36:108113.]

8 ). It is found that the Boussinesq approximation, which was commonly used in the study of natural convection, indeed leads to some noticeable errors in the investigated Ra Range. The errors stemmed from another common approximation of neglecting the viscous dissipation term in the energy equation are investigated too. Finally, evolution of the buoyancy-driven flow in a cubical cavity from transition to chaos is performed using the exact, three-dimensional formulation.

We present a method for self-assembling arrays of live single cells on a glass chip using a photopatternable polymer to form micro-traps. We have studied the single-cell self-assembly method and optimized the process to obtain a 52% yield of single-trapped cells. We also report a method to measure the oxygen consumption rate of a single cell using micro-patterned sensors. These molecular oxygen sensors were fabricated around each micro-trap allowing optical interrogation of oxygen concentration in the immediate environment of the trapped cell. Micromachined micro-wells were then used to seal the trap, sensor and cell in order to determine the oxygen consumption rate of single cells. These techniques reported here add to the collection of tools for performing 'singe-cell' biology. An oxygen consumption rate of 1.05 ± 0.28 fmol min−1 was found for a data set consisting of 25 single A549 cells.