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121.
Francesco Carlà Giulio Campo Claudio Sangregorio Andrea Caneschi César de Julián Fernández Lourdes I. Cabrera 《Journal of nanoparticle research》2013,15(8):1-16
Quantum dots (QDs) have received considerable attention due to their unique optical and electrical properties. Although substantial research has focused on the potential applications and toxicological impacts of QDs, far less effort has been directed toward understanding their fate and transport in the environment. In this work, the effect of four coatings, polyethylene glycol functionalized polymer (PEGP), carboxyl derivatized polymer (COOHP), linoleic acid (LA), and polyacrylic acid-octylamine (PAA-OA), on the transport and retention of QDs in porous media were evaluated under environmentally relevant conditions. Aqueous QD suspensions (ca. 10 nM) were introduced into water-saturated columns packed with 40–50 mesh Ottawa sand at a pore-water velocity of 7.6 m/day. At an ionic strength (IS) of 3 mM and pH of 7, PEGP-coated QDs were completely retained within the column, while more than 60 % of COOHP-coated QDs were transported through a column run under identical conditions. When PAA-OA and LA were used as coatings, effluent QD recoveries increased to more than 65 and 89 % of the injected mass, respectively. Additionally, a decrease in pH from 9.5 to 5.0, or an increase of IS from 0 to 30 mM reduced the eluted mass of PAA-OA-coated QDs by more than 2 and 15 times, respectively. The relative mobility of coated QDs (LA > PAA-OA > COOHP > PEGP) was consistent with total interaction energy profiles between QDs and sand surfaces calculated based on Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. At an IS of 3 mM (NaCl) and pH 7, a linear correlation was obtained between the fraction of eluted QDs and the magnitude of the primary interaction energy barrier. These findings demonstrate the strong dependence of QD transport on coating type and indicate that interaction energies based on DLVO theory can be used to predict the relative mobility of QDs in porous media. 相似文献
122.
Anaí Duarte Wilson Cunico Claudio M.P. Pereira Alex F.C. Flores Rogério A. Freitag Geonir M. Siqueira 《Ultrasonics sonochemistry》2010,17(2):281-283
An ultrasound-enhanced method has been developed for the synthesis of a variety of thioesters from benzoyl chlorides and 2-mercaptobenzoxa(thia)zoles. Applying this methodology, 14 compounds were synthesized in excellent yields. 相似文献
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125.
L. Anfossi F. Di Nardo C. Giovannoli C. Passini C. Baggiani 《Analytical and bioanalytical chemistry》2013,405(30):9859-9867
Silver nucleation on gold has been exploited for signal amplification and has found application in several qualitative and quantitative bio-sensing techniques, thanks to the simplicity of the method and the high sensitivity achieved. Very recently, this technique has been tentatively applied to improve the performance of gold-based immunoassays. In this work, the exploitation of the signal amplification due to silver deposition on gold nanoparticles has been first applied to a competitive lateral flow immunoassay (LFIA). The signal enhancement due to silver allowed us to strongly reduce the amount of the competitor and of specific antibodies employed to build an LF device for measuring ochratoxin A (OTA), thus permitting the attainment of a highly sensitive assessment of OTA contamination, with a sensitivity gain of more than 10-fold compared to the gold-based LFIA that used the same immunoreagents and to all previously reported LFIA for measuring OTA. In addition, a less sensitive “quantitative” LFIA could be established, by suitably tuning competitor and antibody amounts, which was characterized by reproducible and accurate OTA determinations (RSD% 6–12 %, recovery% 82–117 %). The quantitative system allowed a reliable OTA quantification in wines and grape musts at the microgram per liter level requested by the European legislation, as demonstrated by a highly results obtained through the quantitative silver-enhanced LFIA and a reference HPLC-FLD on 30 samples. Figure
The silver enhanced-Lateral Flow ImmunoAssay: strip development based on gold-nanoparticles occurs, followed by the addition of the enhancing solution, which causes the lines to turn black and become more intense, thus increasing detectability. 相似文献
126.
Claudio L. Donnici Elaine Henriques Teixeira Pereira Júlio C. Dias Lopes Liliana Marzorati Blanka Wladislaw 《合成通讯》2013,43(3):342-350
The study on reactivity of several α-substituted α-sulfonyl malonates toward 1,4-diazabicyclo[2.2.2]octane (DABCO) and Bu3N is described. The reactivity with DABCO revealed the possible competition between decarbalkoxylation and unexpected desulfonylation, depending on the α-substituent, because of sterical hindrance around the electrophilic centers (SO2 and CO2R). The derivatives with crowded α-substituents suffer selective desulfonylation, and a novel and efficient desulfonylation method can be proposed. The dependence of the reactivity of α-sulfonyl malonates on the sterical hindrance around the electrophilic centers is confirmed by conformational analysis (Macromodel/MM2? and Mopac/MP3). The carbanionic mechanism is proved because the corresponding protonated, deuterated, and sulfenylated products were obtained by addition of the corresponding electrophilic agents. Bu3N showed itself to be a novel selective decarbalkoxylation agent for any α-substituted α-sulfonyl malonate. 相似文献
127.
An improved One-step Beckmann rearrangement is described. 相似文献
128.
129.
Dihalocarbenes generated under phase transfer conditions add to cis and trans vinylic selenides to give the corresponding 1,1-dihalo-2-selenocyciopropanes with retention of configuration. 相似文献
130.
Antonio Tognazzi Arduino M. Dattilo Luca Bracchini Claudio Rossi Davide Vione 《International journal of environmental analytical chemistry》2013,93(15):1679-1688
It is known that the compound 2,4-dichloro-6-nitrophenol (2,4DC6NP) is formed upon nitration of 2,4-dichlorophenol, which in turn is a transformation intermediate of the herbicide dichlorprop. However, the chemical and spectroscopic characteristics of 2,4DC6NP, as well as its toxicity, are poorly known. This work shows that 2,4DC6NP behaves as a diprotic acid in aqueous solutions, with pKa values of 3.0?±?0.9 and 4.9?±?0.5. At pH?<?3, 2,4DC6NP would undergo protonation. The absorption spectra suggest that anionic 2,4DC6NP, which prevails at pH?>?5 would have an ortho-quinoid structure that is responsible for the absorption peak centred at 428?nm. Considering that 2,4DC6NP has been detected in the brackish lagoons of the Rhône delta (southern France), where its levels are comparable to those of the parent herbicide, it is necessary to examine the possible effects of 2,4DC6NP on the species living in that environment. For this reason, the acute toxicity of the anionic form of 2,4DC6NP was assessed for the brine shrimp Artemia salina, a zooplankton species that lives both in brackish and in saline aquatic environments. The toxicity test yielded a LC20 value of 8?±?2?mg?L?1 and a LC50 value of 18.7?±?0.8?mg?L?1. Such values are safely higher than the maximum detected concentration of 2,4DC6NP in the Rhône delta lagoons. Further studies should be concentrated on the long-term effects of 2,4DC6NP, and in particular on its potential genotoxicity. 相似文献