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Clean
Terms modified by Clean Selected AbstractsGeneralized early-time/late-time evolutionary programming-based CLEANMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2008In-Sik Choi Abstract A novel method, which is called generalized early-time/late-time evolutionary programming (EP)-based CLEAN algorithm, is proposed for simultaneous extraction of the scattering centers and natural resonance frequencies of a radar target. This algorithm uses a duality between the temporal late-time response and spectral early-time response. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 208,210, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23032 [source] Clean and Flexible Modification Strategy for Carboxyl/Aldehyde-Functionalized Upconversion Nanoparticles and Their Optical ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Huan-Ping Zhou Abstract Rare-earth upconversion nanoparticles (UCNPs) exhibit great potential in luminescent biolabels and other multifunctional probes; however, their applications are limited by their low water solubility and the lack of binding groups. To address these problems, a clean and flexible strategy to modify hydrophobic monodisperse UCNPs into hydrophilic ones that are capped with functional groups is developed. The modification process is implemented by direct oxidation of oleic acid ligands with ozone under specific conditions, where the oleic acid (OA) ligands on the surface of the UCNPs can be converted into azelaic acid ligands (HOOC(CH2)7COOH) or azelaic aldehyde HOOC(CH2)7CHO, as is revealed by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) measurements. This oxidation process has no significant side-effects on the morphology, phase, composition, or luminescent properties of the UCNPs. Free carboxylic acid groups on the surface endow the UCNPs with good water solubility, while aldehyde groups at the surface provide binding sites for amino-containing molecules via Schiff-base condensation, such as 2-(4-aminophenylethylyl)-5-methoxy-2-(2-pyridyl)thiazole (MPTEA) and 2-aminoethanethiol hydrochloride (NH2CH2CH2SH·HCl, HEMA). A Ce4+ sensor is constructed based on the dual-emission arising from the different spectral responses of MPTEA and the UCNPs. Facilitated by the covalent linkage between the terminal aldehyde group on the UCNPs and the amino group in HEMA, a hybrid structure of UCNPs and Au NPs is fabricated. The effective coupling between the aldehyde group and the amino group suggests that these functionalized UCNPs have potential in combining other functional units for simultaneous biolabeling, or other optical applications. [source] Comment on the "Keep It Clean and Do the Research" Editorial by Harold R. Wanless, Ground Water 42, no. 2:157GROUND WATER, Issue 4 2004Christopher J. Brown No abstract is available for this article. [source] Highly Convenient, Clean, Fast, and Reliable Sonogashira Coupling Reactions Promoted by Aminophosphine-Based Pincer Complexes of Palladium Performed under Additive- and Amine-Free Reaction ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Jeanne No abstract is available for this article. [source] Highly Convenient, Clean, Fast, and Reliable Sonogashira Coupling Reactions Promoted by Aminophosphine-Based Pincer Complexes of Palladium Performed under Additive- and Amine-Free Reaction ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009Jeanne Abstract Sequential addition of 1,1,,1,,-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to toluene solutions of (cyclooctadiene)palladium dichloride [Pd(cod)(Cl)2] under nitrogen in "one pot" almost quantitatively yielded the aminophosphine-based pincer complexes {[C6H3 -2,6-(XP{piperidinyl}2)2]Pd(Cl)} (X=NH 1; X=O 2). Complex 1 (and to a minor extent 2) proved to be efficient Sonogashira catalysts, which allow the quantitative coupling of various electronically deactivated and/or sterically hindered and functionalized aryl iodides and aryl bromides with several alkynes as coupling partners within very short reaction times and low catalyst loadings. Importantly, in contrast to most of the Sonogashira catalysts, which either are both air- and moisture-sensitive and/or require the addition of co-catalysts, such as copper(I) iodide [CuI], for example, or a large excess of an amine, the coupling reactions were carried out without the use of amines, co-catalysts or other aditives and without exclusion of air and moisture. Moreover, the desired products were exclusively formed (no side-products were detected) without employing an excess of one of the substrates. Ethylene glycol and potassium phosphate (K3PO4) were found to be the ideal solvent and base for this transformation. Experimental observations strongly indicate that palladium nanoparticles are not the catalytically active form of 1 and 2. On the other hand, their transformation into another homogeneous catalytically active species cannot be excluded. [source] Framework for surface water quality management on a river basin scale: Case study of Lake Iseo, Northern ItalyLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 2 2001D. H. A. Al-Khudhairy Abstract River (DESERT) and lake (EVOLA) water quality models are used to simulate the influences of alternative water quality management scenarios on the quality of receiving surface waters in the Lake Iseo basin, Northern Italy. The scenarios are representative of the European Union Directive on Urban Waste Water Treatment (91/271/EEC) and of the regional authority's objective to reduce the total phosphorus loads from point sources entering Lake Iseo and to restore the lake as close as it is practically possible to its former natural qualitative state. Application of DESERT shows that the regional ,Water Clean Up Plan' can achieve similar reductions in total phosphorus concentrations in the basin's main river system, Oglio River, to the 91/271/EEC directive, but at notably lower economic costs. Application of EVOLA to Lake Iseo shows that it is not practical to achieve the regional authority's objective of a specific total phosphorus concentration in the lake by 2016. Instead, the results show that a more realistic, but higher, total phosphorus concentration can be achieved by 2016. The results of both modelling exercises indicate the usefulness of DESERT and EVOLA for comparing and assessing water quality management scenarios and for revising the regional authority's final objectives with regards to total phosphorus concentration in Lake Iseo, as well as the regional ,Water Clean Up Plan' for restoring and safeguarding the quality of the basin's surface waters. [source] Wiping the Slate Clean: The Heart of ForgivenessPHILOSOPHY AND PUBLIC AFFAIRS, Issue 1 2008LUCY ALLAIS First page of article [source] ChemInform Abstract: Clean and Convenient One-Pot Synthesis of 4-Hydroxycoumarin and 4-Hydroxy-2-quinolinone Derivatives.CHEMINFORM, Issue 32 2010Wen-Tao Gao Abstract Advantages of the title procedure are simple experimental and product isolation procedures. [source] ChemInform Abstract: A Clean, Facile, and Stereospecific Synthesis of ,-Oxoketene O,S-Acetals in Water.CHEMINFORM, Issue 27 2009Yan Li Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Clean and Efficient Benzylic C,H Oxidation in Water Using a Hypervalent Iodine Reagent: Activation of Polymeric Iodosobenzene with KBr in the Presence of Montmorillonite-K10.CHEMINFORM, Issue 5 2009Toshifumi Dohi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Clean, One-Pot Synthesis of Naphthopyran Derivatives in Aqueous Media.CHEMINFORM, Issue 46 2006Tong-Shou Jin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] A Clean, Facile and Practical Synthesis of ,-Oxoketene S,S-Acetals in Water.CHEMINFORM, Issue 22 2006Yan Ouyang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Clean and Efficient Microwave Solvent-Free Synthesis of Some Antimicrobial Compounds from 2-Aminothiadiazine.CHEMINFORM, Issue 5 2006V. M. Patel Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Quick, Clean and Green Synthesis of Methylenedioxyprecocene and Other Chromenes over Basic Montmorillonite K10 Clay.CHEMINFORM, Issue 33 2005Matthew R. Dintzner Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Clean and Simple Synthesis of 6-Amino-4-aryl-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano [2,3-c]pyrazole in Water.CHEMINFORM, Issue 27 2005Tong-Shou Jin Abstract For Abstract see ChemInform Abstract in Full Text. [source] Clean and Highly Selective Oxidation of Alcohols in an Ionic Liquid by Using an Ion-Supported Hypervalent Iodine(III) Reagent.CHEMINFORM, Issue 23 2005Weixing Qian Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Clean and Rapid Synthesis of 5-Amino and 5-Alkoxycarbonylpyrazoles Using Montmorillonite under Acid Free Conditions.CHEMINFORM, Issue 10 2005G. Jagath Reddy Abstract For Abstract see ChemInform Abstract in Full Text. [source] Sterile Versus Nonsterile Gloves During Mohs Micrographic Surgery: Infection Rate is not AffectedDERMATOLOGIC SURGERY, Issue 2 2006BRANDON M. RHINEHART MC BACKGROUND: Mohs micrographic surgery (MMS) is an outpatient procedure, which has become the treatment of choice for certain cutaneous malignancies. Although the major steps in this procedure are relatively standardized, one difference involves the use of sterile or nonsterile, clean gloves during the tumor removal phase. OBJECTIVE: This retrospective, chart review study was performed to evaluate whether infection rates are affected by the use of sterile versus nonsterile gloves in the tumor extirpation phase of MMS. METHODS: This study evaluated the surgical records of 1,810 consecutive Mohs patients, of which 1,239 Mohs patients (1,400 Mohs procedures) met inclusion criteria. Age, sex, tumor diagnosis, anatomic location, number of Mohs stages, area of defect, closure type, cartilage exposure, and sterile versus nonsterile glove use were recorded and evaluated. RESULTS: Twenty-five infections were identified. Statistically significant infection rates were discovered for patients with cartilage fenestration with secondary healing and malignant melanoma diagnosis only. There was no statistical difference in infection rates with all other measured variables to include the use of sterile or clean, nonsterile gloves. CONCLUSION: Our study lends support that clean, nonsterile gloves are safe and effective for use in the tumor extirpation phase of MMS, at a significant cost savings. [source] Exfoliative sputum cytology of cancers metastatic to the lung,DIAGNOSTIC CYTOPATHOLOGY, Issue 3 2005Tehmina Z. Ali M.D. Abstract Although largely replaced by fine-needle aspiration (FNA) and bronchoscopy, cytological examination of sputum for exfoliated malignant cells still is considered a valuable initial diagnostic test in patients presenting with a lung mass. Thirty-five cases of secondary/metastatic tumors involving the lung and diagnosed on sputum were retrospectively reviewed from our cytopathology files for a period of 22 yr (1980,2001). Clinical history and the relevant histopathological material were examined and correlated with the cytological findings. In all cases, a history of malignancy was known. Cytological diagnoses included colonic adenocarcinoma (7 cases); non-Hodgkin's lymphoma (NHL; 5 cases); malignant melanoma (MM; 5 cases); breast carcinoma (5 cases); Hodgkin's lymphoma (HL; 3 cases); pancreatic adenocarcinoma (2 cases); prostatic adenocarcinoma (2 cases); and 1 case each of urothelial carcinoma, endometrial carcinoma, renal cell carcinoma, hepatic small-cell carcinoma, squamous-cell carcinoma (cervix), and leiomyosarcoma (LMS). Cellular preservation was optimal in all cases. The smear background was relatively clean in 25 (71%) cases and predominantly inflamed and/or necrotic in 10 (29%) cases. In non-lymphoid tumors (27 cases), isolated single malignant cells were seen in 7 (26%) cases (all cases of MM and prostatic adenocarcinoma), whereas 20 (74%) cases displayed fragments with intact tumor architecture. Overall, only 10/35 (29%) cases showed noticeable tumor-cell necrosis. In one case (LMS), cell block sections were used for immunoperoxidase (IPOX) studies with positive staining for desmin and actin. Exfoliation of cancer cells in sputum from secondary tumors in the lung is a rare phenomenon in current-day practice, with metastatic colonic adenocarcinoma seen most commonly. Intact tumor architecture was observed in exfoliated cells in 75% of the cases. Diagn. Cytopathol. 2005;33:147,151. © 2005 Wiley-Liss, Inc. [source] SPE and large-volume sample stacking in MEKC for determination of doxycycline in biological fluids: Comparison of direct injection to SPE-MEKCELECTROPHORESIS, Issue 21 2008Rade Injac Abstract A novel and simple method has been developed for the determination of doxycycline (DOX) in biological fluids. The method is based on SPE, large-volume sample stacking (LVSS) and MEKC with UV-DAD detection. Six SPE cartridges have been used in investigation for sample clean up and pre-concentration (Supelco® LC-8, LC-18, LC-SCX, and LC-WCX, as well as StrataÔ-X and X-C). DOX was determined on a 56,cm (effective length 50,cm)×50,,m id fused-silica capillary. The BGE was 20,mM borate buffer, pH 9.3, containing 80,mM SDS and 7.5%,v/v of methanol (30,s×50,mbar), and the temperature and voltage were 25°C and 30,kV, respectively. The analytical wavelength was set at 210,nm. Under optimized conditions it is possible to determine DOX in human serum, urine, semen, tears and saliva with recovery of 97.5% (RSD 2.5%). The method was shown to be sensitive (LOD is 1,,g/L) and precise (intra-day RSD 0.2 and 2.4%; inter-days 0.4 and 3.5% for migration time and peak area, respectively). Results for developed SPE-LVSS-MEKC were compared with LVSS-MEKC method with direct sample injection. The new LVSS-MEKC method is presented as a useful technique for rapid determination without extraction procedure of DOX in human urine and serum, using 80,mM of SDS, 10%,v/v of methanol and 40,mM borate buffer (pH 9.3; 30,s×50,mbar; 25°C; 30,kV; 350,nm), but not for the other biological fluids, according to lower sensitivity of the method and because of the sample composition. [source] Tolerance to metals and assessment of energy reserves in the polychaete Nereis diversicolor in clean and contaminated estuariesENVIRONMENTAL TOXICOLOGY, Issue 1 2005C. Durou Abstract Estuaries are subject to anthropogenic activities. Because the intrasedimentary worm Nereis diversicolor has ecological characteristics and bioindicator abilities, its use was pertinent in investigating the concepts and cost of tolerance to heavy metals (Cd, Cu, Zn). In this context, two approaches were carried out, performing toxicity tests and estimating energy reserves (glycogen and lipids), in populations originating from a contaminated site (Seine estuary) compared with those from a clean site (Authie estuary). Mean lethal times (LT50s) of organisms exposed to zinc from the Seine estuary were higher than those from the Authie estuary, but not of organisms exposed to Cd or Cu. The influence of animal weight and salinity on the sensitivity of worms also was studied. The biggest worms were more tolerant to zinc than the smallest ones, and worms survived longer at a reduced salinity (15,). Concentrations of glycogen and lipids in each sampling season were higher in specimens from the Authie estuary than in worms from the Seine estuary. No influence of salinity on glycogen and lipid levels was observed. Glycogen concentrations were not influenced by the weight of specimens, whereas lipid concentrations were significantly and positively correlated with weight. In conclusion, worms from the Seine estuary exhibited tolerance to Zn, and the depletion of energy reserves observed in this population could be interpreted as a cost of tolerance. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 23,31, 2005. [source] Endocrine responses of Fundulus heteroclitus to effluent from a bleached-kraft pulp mill before and after installation of reverse osmosis treatment of a waste streamENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2000Monique G. Dubé Abstract Implementation of process changes on the nonbleaching side of bleached kraft pulp mill (BKPM) operations has increased in recent years to maximize resource use and to minimize residual environmental effects of discharged effluents. The objective of this study was to determine if reverse osmosis (RO) treatment of evaporator and digester clean condensates reduced or removed the effects of a BKPM effluent on reproductive endocrine function of the estuarine killifish, Fundulus heteroclitus (mummichog). Comparison of data collected before (1997) and after (1998), the years of the process change, showed that the potential of the combined mill effluent to depress plasma testosterone levels after 30 and 57 d of exposure to an environmentally relevant effluent concentration (1%) was reduced after RO treatment of condensates. However, in vitro production of some sex steroids was depressed with a 1% effluent exposure after the process change. In addition, in 1998, depression of plasma testosterone levels in effluent-exposed fish was present at higher effluent concentrations (5%). These results are significant because they suggest that condensates may be a source of endocrine-disrupting compounds in BKPM effluents and RO may reduce their discharge. [source] Nonparametric harmonic regression for estuarine water quality dataENVIRONMETRICS, Issue 6 2010Melanie A. Autin Abstract Periodicity is omnipresent in environmental time series data. For modeling estuarine water quality variables, harmonic regression analysis has long been the standard for dealing with periodicity. Generalized additive models (GAMs) allow more flexibility in the response function. They permit parametric, semiparametric, and nonparametric regression functions of the predictor variables. We compare harmonic regression, GAMs with cubic regression splines, and GAMs with cyclic regression splines in simulations and using water quality data collected from the National Estuarine Reasearch Reserve System (NERRS). While the classical harmonic regression model works well for clean, near-sinusoidal data, the GAMs are competitive and are very promising for more complex data. The generalized additive models are also more adaptive and require less-intervention. Copyright © 2009 John Wiley & Sons, Ltd. [source] Population and Species Divergence of Chemical Cues that Influence Male Recognition of Females in Desmognathine SalamandersETHOLOGY, Issue 7 2003Paul Verrell Growing evidence indicates that males may be more discriminating of mating partners than often has been assumed. In the North American Ocoee dusky salamander, Desmognathus ocoee (Plethodontidae: Desmognathinae), sexual incompatibility among conspecific populations is high in encounters staged in the laboratory, at least in part because males fail to recognize ,other' females as appropriate targets for courtship. I used Y-mazes to test the hypothesis that males of D. ocoee discriminate between substrate-borne chemical cues produced by ,own' (homotypic) and ,other' (heterotypic) females. Males of four populations discriminated in favor of substrates soiled by homotypic females over clean (control) substrates (expt 1), suggesting that females produce chemical cues of sociosexual significance to males. Furthermore, males from these populations discriminated in favor of substrates soiled by homotypic females vs. substrates soiled by heterotypic females (expt 2), both conspecific and heterospecific (D. carolinensis and D. orestes). Thus, differences among populations and species in female chemical cues appear to affect the chemotactic responses of males. I suggest that, together with differences in behavioral signals and responses exhibited during courtship, differences in female chemical cues likely contribute to sexual incompatibility among populations and taxa of desmognathine salamanders. [source] Sexual Dimorphism of Mate Location in the Long-Toed Salamander Ambystoma macrodactylum columbianumETHOLOGY, Issue 8 2001Paul Verrell In breeding systems characterized by scramble competition among males, theory predicts that the efficient location of mating partners is more important to males than to females as a component of mating success. We experimentally tested in the laboratory the hypothesis that breeding male long-toed salamanders (Ambystomamacrodactylumcolumbianum), which scramble for mating opportunities, are better able to recognize and locate potential mates than are breeding females. Males were more likely to enter traps containing females than empty traps or traps containing males. Traps containing sponges soiled by females were more likely to attract males than traps containing clean (control) sponges, suggesting that chemical cues may be sufficient for mate location by males. Females were no more likely to enter traps containing males than empty traps. Our results are consistent with the theoretical prediction that selection has been stronger on male long-toed salamanders than on females in the context of capacity for recognizing and locating potential mating partners. [source] Rapid detoxification from opioid dependence under general anaesthesia versus standard methadone tapering: abstinence rates and withdrawal distress experiencesADDICTION BIOLOGY, Issue 3 2003PAUL KRABBE The aim of this work was to study abstinence rates and withdrawal effects of rapid detoxification of opioid-dependents under general anaesthesia (RD-GA) compared to standard methadone tapering (SMT) using a prospective clinical trial with a follow-up of 3 months, as a preliminary study at the Novadic addiction centre in St Oedenrode and St Joseph Hospital in Veghel, the Netherlands. Thirty opioid-dependent patients took part. Outcome measures included urine toxicology screening for opiates to determine abstinence and presence of objective and subjective opioid withdrawal distress symptoms. Statistically significant differences in abstinence rate between RD-GA and SMT were present after one (RD-GA 100% vs. SMT 40%, p <0.01) and 2 months (RD-GA 93% vs. SMT 33%, p <0.01). After 3 months the difference in abstinence was still substantial, but no longer statistically significant (RD-GA 67% vs. SMT 33%, p =0.14). Objective and subjective withdrawal symptoms showed largely identical outcomes and were equally low in the two groups for those who remained in the study. There was a considerably higher percentage of abstinence in the RD-GA group after 1, 2 and 3 months of follow-up accompanied by relatively mild withdrawal symptoms of shorter duration. However, if one completes SMT the data suggest a greater chance of staying clean in the long term than those completing RD-GA. [source] Novel 4-Aminoquinolines through Microwave-Assisted SNAr Reactions: a Practical Route to Antimalarial AgentsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 36 2007Sergio Melato Abstract 4-Aminoquinolines have recently been indicated to be an important class of chemotherapeutic agents for artemisinin-based antimalarial combination therapy. A rapid, cheap, possibly clean and scalable route to 4-aminoquinolines endowed with multiple diversity is therefore badly needed. Classically, they have been prepared by means of SNAr reactions, requiring hazardous or costly reagents and conditions and complex purification procedures. In this paper, microwave flash-heating chemistry is shown to allow the efficient conversion of the available 4,7-dichloroquinoline into a library of aminoquinolines in high yields and purities, with no need for further purification steps and requiring very short reaction times. Some of the compounds in this library were active against chloroquine-sensitive and chloroquine-resistant parasite strains.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Sol-Gel Entrapped Pyridinium Hydrobromide Perbromide as a Recyclable Bromination Agent: Its Application to a One-Pot Bromination and Dehydrobromination ProcessEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2006Yevgenia Levin Abstract Silica sol-gel encaged pyridinium hydrobromide perbromide can be used for clean, odorless bromination of a variety of substrates, including alkenes, ketones, and arenes. The used heterogenized bromination reagent can be recharged with bromine and recycled. In the presence of sol-gel entrapped 1,5,7-triazabicyclo[4.4.0]dec-5-ene, dibromides are dehydrobrominated to give vinyl monobromides and/or alkynes. Encapsulation of the pyridinium derivative and the guanidine base within separate sol-gel matrices enables the use of both opposing reagents in one-pot reactions without their mutual destroying each other. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Solvent-Free Microwave-Assisted Efficient Synthesis of 4,4-Disubstituted 2-OxazolinesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2003Fernando García-Tellado Abstract 4,4-Disubstituted 2-oxazolines have been synthesized by a microwave-promoted solvent-free direct condensation of carboxylic acids and disubstituted ,-amino alcohols in good to excellent yields. Zinc oxide is a very good solid support in cases where a Lewis acid is required. The method described herein is a very good, safe, clean, economical, and environmentally friendly alternative to the classical procedures. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Clean and Flexible Modification Strategy for Carboxyl/Aldehyde-Functionalized Upconversion Nanoparticles and Their Optical ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Huan-Ping Zhou Abstract Rare-earth upconversion nanoparticles (UCNPs) exhibit great potential in luminescent biolabels and other multifunctional probes; however, their applications are limited by their low water solubility and the lack of binding groups. To address these problems, a clean and flexible strategy to modify hydrophobic monodisperse UCNPs into hydrophilic ones that are capped with functional groups is developed. The modification process is implemented by direct oxidation of oleic acid ligands with ozone under specific conditions, where the oleic acid (OA) ligands on the surface of the UCNPs can be converted into azelaic acid ligands (HOOC(CH2)7COOH) or azelaic aldehyde HOOC(CH2)7CHO, as is revealed by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) measurements. This oxidation process has no significant side-effects on the morphology, phase, composition, or luminescent properties of the UCNPs. Free carboxylic acid groups on the surface endow the UCNPs with good water solubility, while aldehyde groups at the surface provide binding sites for amino-containing molecules via Schiff-base condensation, such as 2-(4-aminophenylethylyl)-5-methoxy-2-(2-pyridyl)thiazole (MPTEA) and 2-aminoethanethiol hydrochloride (NH2CH2CH2SH·HCl, HEMA). A Ce4+ sensor is constructed based on the dual-emission arising from the different spectral responses of MPTEA and the UCNPs. Facilitated by the covalent linkage between the terminal aldehyde group on the UCNPs and the amino group in HEMA, a hybrid structure of UCNPs and Au NPs is fabricated. The effective coupling between the aldehyde group and the amino group suggests that these functionalized UCNPs have potential in combining other functional units for simultaneous biolabeling, or other optical applications. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||