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961.
An Amphiphilic BODIPY‐Porphyrin Conjugate: Intense Two‐Photon Absorption and Rapid Cellular Uptake for Two‐Photon‐Induced Imaging and Photodynamic Therapy
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Dr. Tao Zhang Dr. Rongfeng Lan Longlong Gong Dr. Baoyan Wu Yuzhi Wang Dr. Daniel W. J. Kwong Prof. Wai‐Kwok Wong Dr. Ka‐Leung Wong Prof. Da Xing 《Chembiochem : a European journal of chemical biology》2015,16(16):2357-2364
The new amphiphilic BODPY‐porphyrin conjugate BZnPP and its precursor BZnPH were synthesised, and their linear and two‐photon photophysical properties, together with their cellular uptake and photo‐cytotoxicity, were studied. This amphiphilic conjugate consists of a hydrophobic BODIPY moiety and a hydrophilic tetra(ethylene glycol) chain bridging a cationic triphenylphosphonium group to an amphiphilic porphyrin ZnP through acetylide linkers at its meso positions. A large two‐photon absorption cross‐section (σ=1725 GM) and a high singlet oxygen quantum yield (0.52) were recorded. Intense linear‐ and two‐photon‐induced red emissions were also observed for both BZnPP and BZnPH. Further in vitro studies showed that BZnPP exhibited very efficient cellular uptake and strong photocytotoxic but weak dark cytotoxic properties towards human breast carcinoma MCF‐7 cells. In summary, the two‐photon‐induced emission and the potent photo‐cytotoxicity of BZnPP make it an efficacious dual‐purpose tumour‐imaging and photodynamic therapeutic agent in the tissue‐transparent spectral windows. 相似文献
962.
Dual,Site‐Specific Modification of Antibodies by Using Solid‐Phase Immobilized Microbial Transglutaminase
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Dr. Philipp R. Spycher Christian A. Amann Jöri E. Wehrmüller David R. Hurwitz Olivier Kreis Daniel Messmer Andreas Ritler Dr. Andreas Küchler Alain Blanc Dr. Martin Béhé Prof. Dr. Peter Walde Prof. Dr. Roger Schibli 《Chembiochem : a European journal of chemical biology》2017,18(19):1923-1927
Microbial transglutaminase (MTG) was stably solid‐phase immobilized on glass microbeads by using a second‐generation dendronized polymer. Immobilized MTG enabled the efficient generation of site‐specifically conjugated proteins, including antibody fragments, as well as whole antibodies through distinct glutamines and, unprecedentedly, also through lysines with various bifunctional substrates with defined stoichiometries. With this method, we generated dual, site‐specifically modified antibodies comprising a fluorescent probe and a metal chelator for radiolabeling—a strategy anticipated to design antibodies for imaging and simultaneous therapy. Furthermore, we provide evidence that immobilized MTG features higher siteselectivity than soluble MTG. 相似文献
963.
Promising curaua fiber‐reinforced polyester composite for high‐impact ballistic multilayered armor
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Sergio Neves Monteiro Fabio de Oliveira Braga Edio Pereira Lima Luis Henrique Leme Louro Jaroslaw Wieslaw Drelich 《Polymer Engineering and Science》2017,57(9):947-954
A typical multilayered armor system (MAS) is composed of a harder front ceramic tile, which is able to erode heavy ammunition, such as the 7.62 mm bullet, followed by a second layer to further reduce the impact energy. Aramid fabric is a common choice for the second layer. In the present work, polyester matrix composites reinforced with 10 to 30 vol% of curaua fibers, despite having much lower strength and stiffness than aramid fabric, displayed similar trauma indentation in a standard clay witness simulating the human body. Impedance matching and scanning electron microscopy analyses suggest effective energy absorption through ceramic fragment capture by curaua composites. Additionally, because of the high cost of aramid fabric, a full MAS with curaua fiber composite is much cheaper than a MAS composed of aramid fabric. Taking into consideration, both the economical and environmental advantages of natural fibers, it is concluded that curaua fiber‐reinforced polyester composite could replace aramid fabric as the second layer in MASs for personal ballistic protection. POLYM. ENG. SCI., 57:947–954, 2017. © 2016 Society of Plastics Engineers 相似文献
964.
Jorn D. Herner Qi Ying Jeremy Aw Oliver Gao Daniel P. Y. Chang Michael J. Kleeman 《Aerosol science and technology》2013,47(10):827-844
The size and composition of ambient airborne particulate matter is reported for winter conditions at five locations in (or near) the San Joaquin Valley in central California. Two distinct types of airborne particles were identified based on diurnal patterns and size distribution similarity: hygroscopic sulfate/ammonium/nitrate particles and less hygroscopic particles composed of mostly organic carbon with smaller amounts of elemental carbon. Daytime PM10 concentrations for sulfate/ammonium/nitrate particles were measured to be 10.1 μ g m?3, 28.3 μ g m?3, and 52.8 μ g m?3 at Sacramento, Modesto and Bakersfield, California, respectively. Nighttime concentrations were 10–30% lower, suggesting that these particles are dominated by secondary production. Simulation of the data with a box model suggests that these particles were formed by the condensation of ammonia and nitric acid onto background or primary sulfate particles. These hygroscopic particles had a mass distribution peak in the accumulation mode (0.56–1.0 μ m) at all times. Daytime PM10 carbon particle concentrations were measured to be 9.5 μ g m?3, 15.1 μ g m?3, and 16.2 μ g m?3 at Sacramento, Modesto, and Bakersfield, respectively. Corresponding nighttime concentrations were 200–300% higher, suggesting that these particles are dominated by primary emissions. The peak in the carbon particle mass distribution varied between 0.2–1.0 μ m. Carbon particles emitted directly from combustion sources typically have a mass distribution peak diameter between 0.1–0.32 μ m. Box model calculations suggest that the formation of secondary organic aerosol is negligible under cool winter conditions, and that the observed shift in the carbon particle mass distribution results from coagulation in the heavily polluted concentrations experienced during the current study. The analysis suggests that carbon particles and sulfate/ammonium/nitrate particles exist separately in the atmosphere of the San Joaquin Valley until coagulation mixes them in the accumulation mode. 相似文献
965.
Lipid and fatty acyl composition of rat brain capillary endothelia isolated by a new technique 总被引:7,自引:0,他引:7
A method is described for the isolation of pure capillary endothelia from rat brain and the phospholipid composition of these
cells is reported. This method is rapid and requires only a small amount of starting material. It involves: (a) tissue disruption
by high speed homogenization, (b) separation of the capillary endothelia from other brain structures using sucrose gradients,
and (c) a final purification using a glass bead column. Choline and ethanolamine phosphoglycerides were found to be the predominant
lipid classes of these cells amounting to 31.9% and 24.4%, respectively, of total phospholipids. The choline phosphoglycerides
consisted almost exclusively of 1,2-diacyl glycerophosphorylcholine, whereas the ethanolamine phosphoglycerides consisted
of approximately equal amounts of 1,2-diacyl and 1-alk-l’-enyl-2-acyl glycerophosphorylethanolamine. The composition of the
constituent fatty acids of both choline and ethanolamine phosphoglycerides and the alk-1-enyl composition of ethanolamine
phosphoglycerides is reported. Saturated fatty acids accounted for 45% of the total fatty acids in choline phosphoglycerides
and for 53% in ethanolamine phosphoglycerides. Arachidonic acid accounted for approximately 48% of the total fatty acids in
alk-1-enyl ethanolamine phosphoglyceride. 相似文献
966.
Precombustion chambers (PCCs) are an ignition technology for large bore, natural gas engines enabling increased combustion stability while extending the lean limit of operation. A PCC is a small chamber, typically 1–2% of the clearance volume, in which a near-stoichiometric mixture of fuel and air is ignited by a standard spark plug. After the mixture in the PCC is ignited, its pressure rises and expels a flame jet of hot gas mixture into the main chamber. The amount of energy a typical PCC produces is roughly one million times that of a conventional spark plug. In this work the role that the PCC plays in the formation of oxides of nitrogen (NOx) is investigated. Previous research indicates that the PCC is responsible for a significant part of engine-out NOx, especially near the lean limit of engine operation. Experimental results are presented from a large bore lean-burn 2-stroke cycle engine. The data shows that the PCC is responsible for a significant part of engine-out NOx emissions. However, the PCC NOx does not form in the PCC. Rather it forms within the gas jet after it penetrates into the main chamber combustion gases. 相似文献
967.
Polymer brush coatings for combating marine biofouling 总被引:4,自引:0,他引:4
Wen Jing Yang Koon-Gee Neoh En-Tang Kang Serena Lay-Ming Teo Daniel Rittschof 《Progress in Polymer Science》2014
A variety of functional polymer brushes and coatings have been developed for combating marine biofouling and biocorrosion with much less environmental impact than traditional biocides. This review summarizes recent developments in marine antifouling polymer brushes and coatings that are tethered to material surfaces and do not actively release biocides. Polymer brush coatings have been designed to inhibit molecular fouling, microfouling and macrofouling through incorporation or inclusion of multiple functionalities. Hydrophilic polymers, such as poly(ethylene glycol), hydrogels, zwitterionic polymers and polysaccharides, resist attachment of marine organisms effectively due to extensive hydration. Fouling release polymer coatings, based on fluoropolymers and poly(dimethylsiloxane) elastomers, minimize adhesion between marine organisms and material surfaces, leading to easy removal of biofoulants. Polycationic coatings are effective in reducing marine biofouling partly because of their good bactericidal properties. Recent advances in controlled radical polymerization and click chemistry have also allowed better molecular design and engineering of multifunctional brush coatings for improved antifouling efficacies. 相似文献
968.
Nick D. Austin Nikolaos V. Sahinidis Ivan A. Konstantinov Daniel W. Trahan 《American Institute of Chemical Engineers》2018,64(1):104-122
In this article, we investigate reaction solvent design using COSMO‐RS thermodynamics in conjunction with computer‐aided molecular design (CAMD) techniques. CAMD using COSMO‐RS has the distinct advantage of being a method based in quantum chemistry, which allows for the incorporation of quantum‐level information about transition states, reactive intermediates, and other important species directly into CAMD problems. This work encompasses three main additions to our previous framework for solvent design (Austin et al., Chem Eng Sci. 2017;159:93–105): (1) altering the group contribution method to estimate hydrogen‐bonding and non‐hydrogen‐bonding σ‐profiles; (2) ab initio modeling of strong solute/solvent interactions such as H‐bonding or coordinate bonding; and (3) solving mixture design problems limited to common laboratory and industrial solvents. We apply this methodology to three diverse case studies: accelerating the reaction rate of a Menschutkin reaction, controlling the chemoselectivity of a lithiation reaction, and controlling the chemoselectivity of a nucleophilic aromatic substitution reaction. We report improved solvents/mixtures in all cases. © 2017 American Institute of Chemical Engineers AIChE J, 63: 104–122, 2018 相似文献
969.
Polyethylene multiwalled carbon nanotube composites 总被引:4,自引:0,他引:4
Tony McNally Petra Pötschke Michael Murphy Steven E.J. Bell Daniel Bein John Paul Quinn 《Polymer》2005,46(19):8222-8232
Polyethylene (PE) multiwalled carbon nanotubes (MWCNTs) with weight fractions ranging from 0.1 to 10 wt% were prepared by melt blending using a mini-twin screw extruder. The morphology and degree of dispersion of the MWCNTs in the PE matrix at different length scales was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and wide-angle X-ray diffraction (WAXD). Both individual and agglomerations of MWCNTs were evident. An up-shift of 17 cm−1 for the G band and the evolution of a shoulder to this peak were obtained in the Raman spectra of the nanocomposites, probably due to compressive forces exerted on the MWCNTs by PE chains and indicating intercalation of PE into the MWCNT bundles. The electrical conductivity and linear viscoelastic behaviour of these nanocomposites were investigated. A percolation threshold of about 7.5 wt% was obtained and the electrical conductivity of PE was increased significantly, by 16 orders of magnitude, from 10−20 to 10−4 S/cm. The storage modulus (G′) versus frequency curves approached a plateau above the percolation threshold with the formation of an interconnected nanotube structure, indicative of ‘pseudo-solid-like’ behaviour. The ultimate tensile strength and elongation at break of the nanocomposites decreased with addition of MWCNTs. The diminution of mechanical properties of the nanocomposites, though concomitant with a significant increase in electrical conductivity, implies the mechanism for mechanical reinforcement for PE/MWCNT composites is filler-matrix interfacial interactions and not filler percolation. The temperature of crystallisation (Tc) and fraction of PE that was crystalline (Fc) were modified by incorporating MWCNTs. The thermal decomposition temperature of PE was enhanced by 20 K on addition of 10 wt% MWCNT. 相似文献
970.
Sanaa Elbouazzaoui Xavier Courtois Patrice Marecot Daniel Duprez 《Topics in Catalysis》2004,(1):493-496
The deactivation of a Pt/Ba/Al2O3 NO
x
-trap model catalyst submitted to SO2 treatment and/or thermal ageing at 800 °C was studied by H2 temperature programmed reduction (TPR), X-ray diffraction (XRD) and NO
x
storage capacity measurements.The X-ray diffractogram of the fresh sample exhibits peaks characteristic for barium carbonate. Thermal ageing leads to the decomposition of barium carbonate and to the formation of BaAl2O4. The TPR profile of the sulphated sample shows the presence of (i) surface aluminium sulphates, (ii) surface barium sulphates, (iii) bulk barium sulphates. The exposure to SO2 after ageing leads to a small decrease of the surface barium-based sulphates, expected mainly as aluminate barium sulphates. This evolution can be attributed to a sintering of the storage material. TPR experiments also show that thermal treatment at 800 °C after the exposure to SO2 involves the decomposition of aluminium surface sulphates to give mainly bulk barium sulphates, also pointed out by XRD. Thus, the thermal treatment at 800 °C leads to a stabilization of the sulphates.These results are in accordance with the NO
x
storage capacity measurements. On non-sulphated catalysts, the treatment at 800 °C induces to a decrease of the NO
x
storage capacity, showing that barium aluminate presents a lower NO
x
storage capacity than barium carbonate. Sulphation strongly decreases the NO
x
storage capacity of catalysts, whatever the initial thermal treatment, showing that barium sulphates inhibit the NO2 adsorption. Moreover, the platinum activity for the NO to NO2 oxidation is lowered by thermal treatments. 相似文献