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1.
Two vanadium (IV) complexes [VIVO(Haeae-sal)(MeOH)]+ ( 1 ) and [VIVO(Haeae-hyap)(MeOH)]+ ( 2 ) were prepared by reacting [VO(acac)2] with ligands [H2aeae-sal] ( I ) and [H2aeae-hyap] ( II ) respectively. Condensation of 2-(2-aminoethylamino)ethanol with salicylaldehyde and 2-hydroxyacetophenone produces the ligands ( I ) and ( II ) respectively. Both vanadium complexes 1 and 2 are sensitive towards aerial oxygen in solution and rapidly convert into vanadium(V) dioxido species. Vanadium(V) dioxido species crystalizes as the dimeric form in the solid-state. Single-crystal XRD analysis suggests octahedral geometry around each vanadium center in the solid-state. To access the benefits of heterogeneous catalysis, vanadium(V) dioxido complexes were anchored into the polymeric chain of chloromethylated polystyrene. All the synthesized neat and supported vanadium complexes have been studied by a number of techniques to confirm their structural and functional properties. Bromoperoxidase activity of the synthesized vanadium(V) dioxido complexes 3 and 4 was examined by carrying out oxidative bromination of salicylaldehyde and oxidation of thioanisole. In the presence of hydrogen peroxide, 3 shows 94.4% conversion ( TOF value of 2.739 × 102 h−1) and 4 exhibits 79.0% conversion (TOF value of 2.403 × 102 h−1) for the oxidative bromination of salicylaldehyde where 5-bromosalicylaldehyde appears as the major product. Catalysts 3 and 4 also efficiently catalyze the oxidation of thioanisole in the presence of hydrogen peroxide where sulfoxide is observed as the major product. Covalent attachment of neat catalysts 3 and 4 into the polymer chain enhances substrate conversion (%) and their catalytic efficiency increases many folds, both in the oxidative bromination and oxidation of thioether. Polymer supported catalysts 5 displayed 98.8% conversion with a TOF value of 1.127 × 104 h−1 whereas catalyst 6 showed 95.7% conversion with a TOF value of 4.675 × 103 h−1 for the oxidative bromination of salicylaldehyde. These TOF values are the highest among the supported vanadium catalysts available in the literature for the oxidative bromination of salicylaldehyde.  相似文献   
2.
Precise control of in vivo transport of anticancer drugs in normal and cancerous tissues with engineered nanoparticles is key to the future success of cancer nanomedicines in clinics. This requires a fundamental understanding of how engineered nanoparticles impact the targeting‐clearance and permeation‐retention paradoxes in the anticancer‐drug delivery. Herein, we systematically investigated how renal‐clearable gold nanoparticles (AuNPs) affect the permeation, distribution, and retention of the anticancer drug doxorubicin in both cancerous and normal tissues. Renal‐clearable AuNPs retain the advantages of the free drug, including rapid tumor targeting and high tumor vascular permeability. The renal‐clearable AuNPs also accelerated body clearance of off‐target drug via renal elimination. These results clearly indicate that diverse in vivo transport behaviors of engineered nanoparticles can be used to reconcile long‐standing paradoxes in the anticancer drug delivery.  相似文献   
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Bismuth based catalytic system for the asymmetric oxidation of alkyl and aryl benzyl sulfides using t-BuOOH as the oxidant has been investigated. This method affords sulfoxides with high enantioselectivities (up to 98% ee) and good yields in reasonable time. The over oxidized product namely the sulfone was not observed. The described method has wide range of applications, exhibits chemoselectivity/enantioselectivity, and proceeds under mild and environmentally friendly reaction conditions.  相似文献   
5.
A variety of phosphorodiamidate compounds were synthesized from the corresponding phosphorodichloridate intermediates and phosphorus oxychloride. These were completely characterized using different spectroscopic methods and single crystal X-ray diffraction studies on one of them. Studies revealed that water in the presence of a mild Lewis acid like ZnCl2 was found to assist the hydrolysis of the P–N linkage. The proof of this concept was effectively realized through the hydrolysis of hexamethylphosphoramide.  相似文献   
6.
Triarylamines containing a 6H-indolo[2,3-b]quinoxaline core and aromatic units such as phenyl, naphthyl, pyrene, anthracene, or fluorene have been synthesized by employing palladium-catalyzed C-N and C-C coupling reactions and characterized by optical absorption and emission spectra, electrochemical behavior, and thermal studies. Even though the electronic absorption spectra of the compounds were influenced by the nature of the peripheral amines, the emission spectra indicated close similarity for the excited states in these compounds. For the derivatives in which the amines were directly anchored on the 6H-indolo[2,3-b]quinoxaline nucleus, the emission appeared to be dominated by the state localized on the 6H-indolo[2,3-b]quinoxaline chromophore, while in the compounds containing the extended conjugation the fluorescence originated from the polyaromatic linker. The compounds displayed green or yellow emission depending on the nature of the amine segment. All of the dyes displayed one-electron quasi-reversible oxidation couple in the cyclic voltammograms, which is attributable to the oxidation of the peripheral amines at the 6H-indolo[2,3-b]quinoxaline core. An additional one-electron oxidation process observable at the high positive potentials for the compounds 7 and 8 probably arises from the oxidation of the arylthiophene segment. The enhanced thermal stability and relatively higher glass transition temperatures observed for these compounds were attributed to the presence of dipolar 6H-indolo[2,3-b]quinoxaline segment. The origin of the optical spectra and the trends observed therein were rationalized using TDDFT simulations.  相似文献   
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The application of near infrared spectroscopy in bioprocessing has been limited by its dependence on calibrations derived from single bioreactor at a given time. Here, we propose a multiplexed calibration technique which allows calibrations to be built from multiple bioreactors run in parallel. This gives the flexibility to monitor multiple vessels and facilitates calibration model transfer between bioreactors. Models have been developed for the two key analytes: glucose and lactate using Chinese hamster ovary (CHO) cell lines and using analyte specific information obtained from the feasibility studies. We observe slight model degradation for the multiplexed models in comparison to the conventional (single probe) models, decrease in r2 values from 89.4% to 88% for glucose whereas for lactate from 92% to 91.8% and a simultaneous increase in the number of factors as the model incorporates the inter-probe variability, nevertheless the models were fit for purpose. The results of this particular application of implementing multiplexed-NIRS to monitor multiple bioreactor vessels are very encouraging, as successful models have been built on-line and validated externally, which proffers the prospect of reducing timelines in monitoring the vessels considerably, and in turn, providing improved control.  相似文献   
9.
Emissive probes are the tools for the direct deter- mination of the plasma potential ~PL and they deliver a more reliable measure of φPL compared to the indi- rect measurements with cold Langmuir probes. The emissive probe works on the principle of compensating the well-known asymmetry of the I-V characteristic of a single cold Langmuir probe by an electron emission current from the probe into the plasma. In an ideal case, the saturated value of floating potential V(А,em) of a highly emissive probe should equal the plasma potential. A conventional emissive probe usu- ally consists of a loop of tungsten wire heated by an electric current passing through it. These conven- tional emissive probes containing an electric current- heated metal wire loop suffer a huge drawback when it comes to their lifetime. The metal wire used in these probes evaporates and subsequently breaks when heated with high current, leading to frequent replacements of these wires. When used in ultra high vacuum (UHV) plasma systems, frequent replacement of these wires requires frequent vacuum breaks in the plasma systems. In many plasma systems espe- cially in magnetized toroidal hot plasmas like toka- maks, where determination of the electric fields leads to a great deal of useful information, frequent breaking of the vacuum is impossible for changing the filament of the emissive probes. Hence, along with the other drawbacks of the conventional emissive probes such as limited emission current, bending in a magnetic field makes their use impractical in these plasma systems. The most suitable alternative is the emissive probes heated by a focused infra-red laser. Due to them having several advantages over the conventional emis- sive probes, laser heated emissive probes (LHEPs) are found to have more and more uses in plasma systems. The advantages of the LHEP are: longer lifetime (no filament breaking issues), attainment of higher tem- perature without melting or evaporation and thus higher emissivity, no deformation of the pr  相似文献   
10.
A variety of sulfides were converted to the corresponding sulfoxide derivatives with 70% t‐BuOOH (water) as the oxidant in the presence of catalytic quantity of Fe2(SO4)3. The method described has a wide range of applications, involves simple work‐up, exhibits chemoselectivity/enantioselectivity and proceeds under mild reaction conditions. The resulting products are obtained in good yield within a reasonable time. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
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