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971.
Selectivity of amine-terminated poly(amidoamine) (PAMAM-AT) dendrimers as host molecules for phenol blue and Nile red guests was investigated using absorption and fluorescence spectroscopies. Phenol blue has been known to associate near the core in the PAMAM-AT dendrimers. Nile red has also been shown to associate with this dendrimer family; however, this occurs in the outermost branches. Concentration ratios and generational dependencies were investigated. It was found that phenol blue was sequestered in the PAMAM-AT dendrimers in the presence of the interfering Nile red, and this association appeared to be the same as that of PAMAM-AT with phenol blue alone. As the concentration of Nile red increased relative to the concentration of phenol blue, the desired association of phenol blue became increasingly hindered. While the presence of Nile red did affect association, phenol blue still had considerable association even when Nile red was in ten-fold excess. The association of phenol blue with PAMAM-AT was stable and robust; however, Nile red's association was relatively weak and unstable. 相似文献
972.
In this report, we have used DNA Y-junctions as fluorescent scaffolds for EcoRII methyltransferase-thioredoxin (M.EcoRII-Trx) fusion proteins. Covalent links between the DNA scaffold and the methyltransferase were formed at preselected sites on the scaffold containing 5FdC. The resulting thioredoxin-targeted nanodevice was found to bind selectively to certain cell lines but not to others. The fusion protein was constructed so as to permit proteolytic cleavage of the thioredoxin peptide from the nanodevice. Proteolysis with thrombin or enterokinase effectively removed the thioredoxin peptide from the nanodevice and extinguished cell line specific binding measured by fluorescence. A number of potential applications for devices of this type can be envisioned. In particular, the ability of the fused protein to selectively target the nanodevice to certain tumor cell lines and not others suggests that this approach may serve as an adjunct to immunohistochemical methods in tumor classification as well as probe cell surface receptor architecture and function. 相似文献
973.
Gerard Back Michael Boosinger Eric Forssell David Beene Elizabeth Weaver Lou Nash 《Fire Technology》2009,45(1):43-69
Full-scale fire tests were conducted by the United States Coast Guard to identify the fire extinguishing capabilities and
limitations of Aerosol Extinguishing Systems (AES) in shipboard machinery space applications. A total of 18 tests were conducted
in this evaluation utilizing the equipment from three AES manufacturers (Ansul, FirePro, and Flame Guard). The systems were
tested against the current International Maritime Organization’s (IMO) test protocol (MSC/Circ. 1007) for approving AES for
machinery space applications. All three systems exhibited good capabilities against Class B fires but had difficulty extinguishing
the Class A fires. As a result of these limited capabilities against Class A fires, none of the three systems successfully
met the requirements of the IMO test protocol (as currently written). The conditions in the space produced by the discharge
of the systems were also quantified during these tests (visibility, temperature, particle densities, and gas concentrations).
Based on the results of these tests, a number of modifications to the procedures, instrumentation, and fire scenarios in the
test protocol were recommended. 相似文献
974.
Whole lake selective withdrawal experiment to control harmful cyanobacteria in an urban impoundment 总被引:1,自引:0,他引:1
Different environmental conditions support optimal growth by Aphanizomenon and Microcystis in Ford Lake, Michigan, USA, based on weekly species biovolume and water chemistry measurements from June through October 2005-2007. Experimental withdrawal of hypolimnetic water through the outlet dam was conducted in 2006, with 2005 and 2007 acting as control years, to test theory regarding management of nuisance and toxic cyanobacteria. The dynamics of Aphanizomenon and Microcystis blooms in Ford Lake appear to be driven largely by NO3− concentrations, with higher levels shifting the advantage to Microcystis (P < 0.0001). Aphanizomenon was most successful with a mean TN:TP ratio (mol:mol) of 48.3:1, whereas Microcystis thrived with a mean ratio of 70.1:1. Withdrawal of hypolimnetic water successfully destabilized the water column and led to higher levels of NO3− and the near elimination of the Aphanizomenon bloom in 2006 (P < 0.0001). Selective withdrawal did not reduce Microcystis biovolume or microcystin toxicity. Microcystis biovolume and NO3− levels were positively correlated with microcystin toxin (P = 0.01) and jointly accounted for 30.5% of the variability in the data. Selective withdrawal may be a viable management option for improving water quality under certain circumstances. To fully address the problem of nuisance and toxic algal blooms in Ford Lake, however, an integrated approach is required that targets cyanobacteria biovolume dynamics as well as conditions suited for toxin production. 相似文献
975.
Currently, magnetic iron oxide nanoparticles are the only nanosized magnetic resonance imaging (MRI) contrast agents approved for clinical use, yet commercial manufacturing of these agents has been limited or discontinued. Though there is still widespread demand for these particles both for clinical use and research, they are difficult to obtain commercially, and complicated syntheses make in-house preparation unfeasible for most biological research labs or clinics. To make commercial production viable and increase accessibility of these products, it is crucial to develop simple, rapid and reproducible preparations of biocompatible iron oxide nanoparticles. Here, we report a rapid, straightforward microwave-assisted synthesis of superparamagnetic dextran-coated iron oxide nanoparticles. The nanoparticles were produced in two hydrodynamic sizes with differing core morphologies by varying the synthetic method as either a two-step or single-step process. A striking benefit of these methods is the ability to obtain swift and consistent results without the necessity for air-, pH- or temperature-sensitive techniques; therefore, reaction times and complex manufacturing processes are greatly reduced as compared to conventional synthetic methods. This is a great benefit for cost-effective translation to commercial production. The nanoparticles are found to be superparamagnetic and exhibit properties consistent for use in MRI. In addition, the dextran coating imparts the water solubility and biocompatibility necessary for in vivo utilization. 相似文献
976.
Yucelen GI Kang DY Guerrero-Ferreira RC Wright ER Beckham HW Nair S 《Nano letters》2012,12(2):827-832
We demonstrate new molecular-level concepts for constructing nanoscopic metal oxide objects. First, the diameters of metal oxide nanotubes are shaped with angstrom-level precision by controlling the shape of nanometer-scale precursors. Second, we measure (at the molecular level) the subtle relationships between precursor shape and structure and final nanotube curvature. Anionic ligands are used to exert fine control over precursor shapes, allowing assembly into nanotubes whose diameters relate directly to the curvatures of the 'shaped' precursors. 相似文献
977.
Elizabeth D. Camarinha Patrícia F. Lito Bruno M. Antunes Marta Otero Zhi Lin Joo Rocha Eduarda Pereira Armando C. Duarte Carlos M. Silva 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2009,155(1-2):108-114
In this work, the removal of Cd2+ ions from aqueous solution using microporous titanosilicate ETS-10 was investigated in order to assess its potential as decontaminating agent in tertiary treatments. Accordingly, batch stirred tank experiments were carried out to study the ion exchange kinetics and equilibrium. Results show that pH affects considerably the ion exchange capability of ETS-10: at pH 4 it is 1.567 × 102 eq m−3, at pH 6 it is 3.629 × 103, and no further increment was observed at pH 8. This is an extremely important observation since pH of industrial effluents and other wastewaters rounds 6. Both Langmuir and Langmuir–Freundlich isotherms were fitted to the experimental data measured. The second model performs slightly better as the calculated absolute average deviations show: AADL = 2.94% and AADLF = 2.40%. Concerning the kinetic behavior, the ion exchange was successfully represented by a Nernst–Planck based model (AAD = 11.9%). 相似文献
978.
G.K. Surya Prakash Sujith Chacko Chiradeep Panja Tisa Elizabeth Thomas Laxman Gurung Golam Rasul Thomas Mathew GeorgeA. Olah 《Advanced Synthesis \u0026amp; Catalysis》2009,351(10):1567-1574
Solid hydrogen peroxide complexes based on poly(N‐vinylpyrrolidone) and poly(4‐vinylpyridine) were prepared and used as solid hydroxylating reagents. These solid hydrogen peroxide equivalents are found to be much safer, convenient and efficient reagent systems for the ipso‐hydroxylation of arylboronic acids to the corresponding phenols in high yields at a faster rate. The versatility of the reagents has been further expanded for the one‐pot synthesis of halophenols. Density functional theory calculations were carried out on hydrogen peroxide complexes of N‐ethylpyrrolidone and 4‐ethylpyridine as models to get a better understanding of structure and behavior of hydrogen peroxide complexes of the polymers poly(N‐vinylpyrrolidone) and poly(4‐vinylpyridine) compared to aqueous hydrogen peroxide. 相似文献
979.
980.
Oswaldo Augusto Filho Jonnhy Norio Hirai André Silva Oliveira Elizabeth Shen Liotti 《Bulletin of Engineering Geology and the Environment》2010,69(4):631-641
The paper presents the development of a decision support system for the management of geotechnical and environmental risks in oil pipelines using a geographical information system. The system covers a 48.5 km long section of the São Paulo to Brasília (OSBRA) oil pipeline, which crosses three municipalities in the northeast region of the São Paulo state (Brazil) and represents an area of 205.8 km2. The spatial database was created using geo-processing procedures, surface and intrusive investigations and geotechnical reports. The risk assessment was based mainly on qualitative models (relative numeric weights and multicriteria decision analysis) and considered pluvial erosion, slope movements, soil corrosion and third party activities. The maps were produced at a scale of 1:10,000. 相似文献