Academic literature on the topic 'ZnS QDs'
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Journal articles on the topic "ZnS QDs"
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Liu, Jing, Ming Ying, Yu Ling Tan, and Bo Xi. "Photoluminescent Characteristics of ZnS Quantum Dots Synthesized in Non-Aqueous-Phase." Advanced Materials Research 750-752 (August 2013): 991–94. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.991.
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ZnS quantum dots (ZnS QDs) synthesized in aqueous solution is easy to gather a mass, which always results in low quantum yield. So, in this study benzene was used as reaction medium in which ZnS QDs with different hues were synthesized, and the hues of ZnS QDs were depend on the molar ratio of Zn (CH3COO)2 and Na2S·9H2O. The results show the emission spectra of ZnS QDs shifts with the change of the precursor molar ratio but the absorption peak at 310nm is not. The emission peaks centered at 430nm and 580nm at higher molar ratio [Zn2+]/[S2-] with blue-violet emitting phosphors; but, ZnS QDs synthesized at higher molar ratio [S2-]/[Zn2+] have orange-red emission at 580nm only. The X-ray diffraction analysis shows the crystallinity of ZnS QDs is better at [Zn2+]/[S2-]=1:10, which are typical zinc blend with nanorod structure.
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Fu, Yan, Daekyoung Kim, Wei Jiang, Wenping Yin, Tae Kyu Ahn, and Heeyeop Chae. "Excellent stability of thicker shell CdSe@ZnS/ZnS quantum dots." RSC Advances 7, no. 65 (2017): 40866–72. http://dx.doi.org/10.1039/c7ra06957j.
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Evolution of the long-term (400 h) thermal stability of green CdSe@ZnS alloyed core/shell QDs (A-QDs) and CdSe@ZnS/ZnS (alloyed core/shell)/thick shell QDs (AS-QDs) under 85 °C, 85% relative humidity conditions in air.
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Chang, Kai-Ping, Yu-Cheng Yeh, Chung-Jui Wu, Chao-Chun Yen, and Dong-Sing Wuu. "Improved Characteristics of CdSe/CdS/ZnS Core-Shell Quantum Dots Using an Oleylamine-Modified Process." Nanomaterials 12, no. 6 (March 9, 2022): 909. http://dx.doi.org/10.3390/nano12060909.
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CdSe/CdS with ZnS/ZnO shell quantum dots (QDs) are synthesized by a one-pot method with various oleylamine (OLA) contents. The crystal structures of the QDs were analyzed by X-ray diffractometry, which showed ZnS diffraction peaks. It was represented that the ZnS shell was formed on the surface of the CdSe/CdS core. Interestingly, QDs with a high OLA concentration exhibit diffraction peaks of ZnS/ZnO. As a result, the thermal stability of QDs with ZnS/ZnO shells exhibits better performance than those with ZnS shells. In addition, the photoluminescence intensity of QDs with ZnS/ZnO shells shows a relatively slow decay of 7.1% compared with ZnS shells at 85 °C/85% relative humidity aging test for 500 h. These indicate that QDs with different OLA modifications can form ZnS/ZnO shells and have good stability in a harsh environment. The emission wavelength of QDs can be tuned from 505 to 610 nm, suitable for micro-LED display applications.
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Liu, Wei, Xian Lan Chen, Ju Cheng Zhang, Yun Hui Long, Ling Shi, and Na Wu. "Preparation ZnS Quantum Dots via Water-Phase Synthesis Method." Advanced Materials Research 706-708 (June 2013): 230–33. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.230.
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With water as the medium, PVP as stabilizer and ammonia as complexing agents and adjusting pH value of the solution, we report an all-aqueous synthesis of highly photoluminescent and stable ZnS quantum dots (QDs) by water-phase synthesis reaction between ZnCl2 and NaS at different temperatures and times. The optimal reaction conditions of PVP-capped ZnS QDs were obtained through experiment as follows: the concentration ZnCl2 and NaS solution both are 1 mM, (PVP):(ZnCl2) = 0.0167 (v/v), (NH3):(ZnCl2)=1:300 (v/v), the optimal reaction temperature is 40 °C, the optimal reaction time is 30 min. With ammonia as complexing agents, Zn(OH)2 can dissolve in ammonia and form to complex ions ((Zn(NH3)4)2+), which make Zn2+ release slowly to control the nucleus growth rate of ZnS, thus obtain small size of nanoparticles. The fluorescence spectra shows that the emission peaks of ZnS QDs around ~395 nm and ~470 nm on the emission spectra, which are consistent with literatures, so nano-ZnS QDs was synthesized successfully in this paper.
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Hong, Wuding, Huijuan Kuang, Xingping He, Lin Yang, Pengfei Yang, Bolu Chen, Zoraida Aguilar, and Hengyi Xu. "CdSe/ZnS Quantum Dots Impaired the First Two Generations of Placenta Growth in an Animal Model, Based on the Shh Signaling Pathway." Nanomaterials 9, no. 2 (February 14, 2019): 257. http://dx.doi.org/10.3390/nano9020257.
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The toxicity, especially the transgenerational toxicity of quantum dots (QDs) in vivo, is still scarcely understood in spite of great promising applications of QDs in biomedicine. In this study, the maternal status, pregnancy outcome, and fetus development of parental generation (P0) to offspring in three generations (F3) were investigated after Kunming mice perinatal (GD 13-PND 5) exposure to Cd containing QDs (CdSe/ZnS QDs) and CdCl2. The results show CdSe/ZnS QDs induced placenta injuries in P0 and diminished placenta diameters in F1 and F2. Bodyweight growth decreased in the CdSe/ZnS QDs treatment group in the F1 and F2 generation. Additionally, CdSe/ZnS QDs significantly altered the expression of key genes in the Shh signal pathway. Overall, this study exhibited that the CdSe/ZnS QDs exposure during perinatal period impaired placenta growth in the first two generations, but not on the third generation. The toxicological actions of the CdSe/ZnS QDs might be through the effects on the Shh signal pathway.
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Su, Yu Yang, Kai Ling Liang, and Chyi Ming Leu. "Cd-Free Quantum Dot Dispersion in Polymer and their Film Molds." Advances in Science and Technology 98 (October 2016): 38–43. http://dx.doi.org/10.4028/www.scientific.net/ast.98.38.
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Indium phosphide (InP) quantum dots (QDs) with luminescence tunable over the entire visible spectrum were prepared by the conventional hot injection method. InP QDs are considered alternatives to Cadmium containing QDs for application in light-emitting devices because of showing similar optical properties to those containing toxic heavy metals. The multishell coating was shown to improve the photoluminescence quantum yield (QY) of InP QDs more strongly than the conventional ZnS shell coating. QY values were more than 60% along with FWHM of 41-73 nm can be routinely achieved, making the optical performance of InP/ZnS/ZnS or InP/ZnS/SiO2 QDs comparable to that of InP/ZnS QDs. These QDs and the polymer dissolved in the appropriate solvent and deposited by casting to give homogeneous films and showed a good level of dispersion of the QDs within the polymer.
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Lian, Linyuan, Youyou Li, Daoli Zhang, and Jianbing Zhang. "Synthesis of Highly Luminescent InP/ZnS Quantum Dots with Suppressed Thermal Quenching." Coatings 11, no. 5 (May 17, 2021): 581. http://dx.doi.org/10.3390/coatings11050581.
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InP quantum dots (QDs) are promising down-conversion phosphors for white light LEDs. However, the mainstream InP QDs synthesis uses expensive phosphorus source. Here, economic, in situ-generated PH3 is used to synthesize InP QDs and a two-step coating of ZnS shells is developed to prepare highly luminescent InP/ZnS/ZnS QDs. The QDs show a photoluminescence quantum yield as high as 78.5%. The emission can be tuned by adjusting the halide precursor and yellow emissive InP/ZnS/ZnS QDs are prepared by judiciously controlling the synthetic conditions. The yellow QDs show suppressed thermal quenching and retain >90% room temperature PL intensity at 150 °C for the growth solution. Additionally, the PL spectrum matches with the eye sensitivity function, resulting in efficient InP QD white light LEDs.
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Chen, Xuan Lin, Yu Qiu Qu, Gui Fan Li, Hong Wei, Liu Yang Zhang, and Li Min An. "Effect of Charge Transferring Materials on Photoluminescence Properties of CdSe/ZnS Quantum Dots." Advanced Materials Research 981 (July 2014): 879–82. http://dx.doi.org/10.4028/www.scientific.net/amr.981.879.
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The CdSe/ZnS core/shell quantum dots (QDs) were synthesized and characterized with absorption spectrometry, photoluminescence (PL) spectrometry and transmission electron microscopy. PL quenching of colloidal CdSe/ZnS QDs in the presence of charge transferring material was studied by means of steady-state and time-resolved PL spectroscopy. With increasing charge transferring materials concentration in the CdSe/ZnS QDs solution, the PL intensity and lifetime of CdSe/ZnS QDs decrease gradually. The quenching efficiency of CdSe/ZnS QDs decrease with increasing the oxidation potential of charge transferring materials. Based on the analysis, there are two pathways in the PL quenching process: static quenching and dynamic quenching. The dynamic quenching is correlated with hole transfer from QDs to the charge transferring materials.
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Abib, Mukerem Helil, Taotao Chen, Enze Xu, Man Wang, and Yang Jiang. "Synthesis of Eco-Friendly High PL Lifespan Manganese-Doped CuInZnS/ZnS QDs for White LED Applications." Journal of Nanoscience and Nanotechnology 20, no. 10 (October 1, 2020): 6286–94. http://dx.doi.org/10.1166/jnn.2020.18585.
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Environmentally friendly and long PL lifespan Mn-doped CuInZnS (Mn:CIZS) and CuInZnS/ZnS (Mn:CIZS/ZnS) QDs, with respective red and yellow emissions, were synthesized using nontoxic precursors via a facile dual-step process based on the one-pot method. The resulting Mn:CIZS and Mn:CIZS/ZnS QDs exhibited confirmed strong red and yellow photoluminescence emissions at approximately 654 nm and 580 nm, respectively. The measured PL decay lifespan for the Mn: CIZS QDs is 2.52 μs due to well-organized surface passivation through the ZnS shell; the average PL lifespan for the Mn:CIZS/ZnS QDs is extended to 6.28 μs. Moreover, the WLEDs were composed of the Mn:CIZS/ZnS QDs. The resulting WLEDs offered admirable optical attributes, such as an excellent Ra of 89, a low Tc of 5075 K and radiant white light emanation at 60 mA functional current. Therefore, the outputs highlight the Mn:CIZS/ZnS QDs as hopeful cadmium-free resources for the interest of optoelectronics exploration.
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Zhang, Xin, Meng Wang, Yating Zhang, Pan Zhao, Jiamei Cai, Yunjian Yao, and Jiarong Liang. "Preparation of Molecularly Imprinted Cysteine Modified Zinc Sulfide Quantum Dots Based Sensor for Rapid Detection of Dopamine Hydrochloride." Molecules 28, no. 9 (April 22, 2023): 3646. http://dx.doi.org/10.3390/molecules28093646.
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By combining surface molecular imprinting technology with cysteine-modified ZnS quantum dots, an elegant, molecularly imprinted cysteine-modified Mn2+: ZnS QDs (MIP@ZnS QDs) based fluorescence sensor was successfully developed. The constructed fluorescence sensor is based on a molecularly imprinted polymer (MIP) coated on the surface cysteine-modified ZnS quantum dots and used for rapid fluorescence detection of dopamine hydrochloride. The MIP@ZnS quantum dots possess the advantages of rapid response, high sensitivity, and selectivity for the detection of dopamine hydrochloride molecules. Experimental results show that the adsorption equilibrium time of MIP@ZnS QDs for dopamine hydrochloride molecules is 12 min, and it can selectively capture and bind dopamine in the sample with an imprinting factor of 29.5. The fluorescence quenching of MIP@ZnS QDs has a good linear (R2 = 0.9936) with the concentration of dopamine hydrochloride ranged from 0.01 to 1.0 μM, and the limit of detection is 3.6 nM. In addition, The MIP@ZnS QDs demonstrate good recyclability and stability and are successfully employed for detection of dopamine hydrochloride in urine samples with recoveries was 95.2% to 103.8%. The proposed MIP@ZnS QDs based fluorescent sensor provides a promising approach for food safety detection and drug analysis.
Dissertations / Theses on the topic "ZnS QDs"
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Raevskaya, Alexandra, Vladimir Lesnyak, Danny Haubold, Volodymyr Dzhagan, Oleksandr Stroyuk, Nikolai Gaponik, Dietrich R. T. Zahn, and Alexander Eychmüller. "A Fine Size Selection of Brightly Luminescent Water-Soluble Ag-In-S and Ag-In-S/ZnS Quantum Dots." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-226647.
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A size-selected series of water-soluble luminescent Ag–In–S (AIS) and core/shell AIS/ZnS QDs were produced by a precipitation technique. Up to 10–11 fractions of size-selected AIS (AIS/ZnS) QDs emitting in a broad color range from deep-red to bluish-green were isolated with the photoluminescence (PL) quantum yield reaching 47% for intermediate fractions. The size of the isolated AIS (AIS/ZnS) QDs varied from ~2 nm to ~3.5 nm at a roughly constant chemical compo- sition of the particles throughout the fractions as shown by the X-ray photoelectron spectroscopy.
The decrease of the mean AIS QD size in consecutive fractions was accompanied by an increase of the structural QD imperfection/disorder as deduced from a notable Urbach absorption “tail” below the fundamental absorption edge. The Urbach increased from 90–100 meV for the largest QDs up to 350 meV for the smallest QDs, indicating a broadening of the distribution of sub-bandgap states. Both the Urbach energy and the PL bandwidth of the size-selected AIS QDs increased with QD size reduction from 3–4 nm to ~2 nm and a distinct correlation was observed between these parameters.
A study of size-selected AIS and AIS/ZnS QDs by UV photoelectron spectroscopy on Au and FTO substrates revealed their valence band level EVB at ~6.6 eV (on Au) and ~7 eV (on FTO) and pinned to the Fermi level of conductive substrates resulting in a masking of any possible size- dependence of the valence band edge position.
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Moussa, Hatem. "Influence de l’association de quantum dots ZnO avec des ions Cu²+ sur leur (photo)toxicité. Nouveaux matériaux ZnO/rGO pour la photocatalyse solaire." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0036/document.
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Ces dernières années, les énormes progrès réalisés en nanotechnologie ainsi qu’en science des matériaux ont conduit à la préparation de nombreuses nouvelles nanoparticules sans réellement connaître l’ensemble des propriétés associées à leurs dimensions. La première partie de notre travail vise à évaluer les risques et les problèmes associés aux nanomatériaux, en termes de toxicité, en utilisant des nanoparticules de ZnO. Nous avons tout d’abord étudié la capacité de ces nanoparticules à générer des espèces réactives d’oxygènes (EROs) sous irradiation UV en utilisant trois types des quantum dots (QDs) comme modèles, ZnO, ZnO dopé avec des ions Cu2+ et ZnO avec des ions Cu2+ adsorbés à sa surface. Les trois types des QDs ont montré une forte capacité à générer des EROs mais ceux modifiés par les ions Cu2+ en périphérie sont les plus producteurs. Ces QDs inhibent également le plus fortement la croissance de la bactérie E. coli. La toxicité n’est cependant pas dépendante des EROs photo-produits ni du zinc (+2) libéré par les QDs et montre qu’un mécanisme plus complexe doit être considéré. Dans une second partie, nous avons tenté d’améliorer l’activité photocatalytique de nanobâtonnets de ZnO en les associant à de l’oxyde de graphène réduit (rGO). Des nanocomposites ZnO/rGO ont été préparés par voie solvothermale et utilisés pour la phototodégradation du colorant Orange II comme modèle de polluant. Les résultats obtenus montrent que le photocatalyseur ZnO/rGO est très efficace sous irradiation solaire ou visible et qu’il est peu sensible à des variations de pH ou à la présence de perturbateurs dans le milieu. Finalement, le photocatalyseur est très stable et peut être réutilisé plus de dix fois sans perte notable d’activitéIn recent years, tremendous advances in nanotechnology and materials science have led to the synthesis of many new nanoparticles without really knowing all the properties associated with their dimensions. The first part of our work aims to evaluate the risks and problems associated with nanomaterials, in terms of toxicity, using ZnO nanoparticles. We first studied the ability of these nanoparticles to produce reactive oxygen species (ROS) under UV irradiation using three ZnO-based quantum dots (QDs) as models, ZnO, ZnO doped with Cu2+ ions and ZnO with chimisorbed Cu2+ ions at their periphery. The three QDs have a strong capacity of generating ROS but those modified with Cu2+ at their surface were found the be the highest producers. These dots were also found to inhibit more markedly the growth of the E. coli bacteria. The toxicity does neither depend on the amount of photo-generated ROS nor on the amount of Zn(+2) leaked by the QDs, thus indicating that a more complex mechanism should be considered. In a second part, we tried to improve the photocatalytic efficiency of ZnO nanorods by associating these nanomaterials with reduced graphene oxide (rGO). ZnO/rGO composites were prepared by a solvothermal method and applied for the photodegradation of Orange II used as model pollutant. Results obtained demonstrate that the ZnO/rGO photocatalyst is highly efficient under solar and under visible light irradiation and weakly sensitive to pH changes and to the presence of perturbators in the reaction medium. Finally, the photocatalyst is stable and can be reused up to ten times without significant loss of catalytic activity
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Tao, Zhi. "Photodétection dans une large gamme de longueur d’onde : phototransistor CdSe QDs/RGO sur des nanofils de ZnO dans la gamme UV-Vis, PbS QDs avec un transistor organique C60 de type N imprimé dans la gamme proche IR." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S087.
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La détection de lumière dans une large gamme de longueur d’onde allant de l’UV au proche infrarouge est réalisée avec une sensibilité importante en utilisant l’effet d’amplification amené par un transistor à effet de champ et la capacité de détection dans une grande gamme de longueur d’onde amenée par des nanoparticules de CdSe et de PbS de diamètres différents. Dans une première partie, un FET utilisant une couche active de nanofils de ZnO est fabriqué. La détection de lumière UV-Vis est assurée en enrobant ces nanofils par un mélange de nanoparticules de CdSe et d’oxyde de graphène. L’oxyde de graphène assure une bonne transition des électrons crées par la lumière dans le CdSe vers le ZnO. La photo-réponse obtenue, supérieure à 104 A/W à 350 nm, a été multipliée par un facteur 100 dans la gamme 200-500nm en utilisant l’oxyde de graphène. Dans une seconde partie, la détection de lumière infrarouge a été assurée par des nanoparticules de PbS incorporées dans un transistor organique de type N utilisant du C60 comme couche active. Les électrodes en argent de ce transistor et son isolant de grille en photorésine SU8 sont déposés par impression. Les nanoparticules sont déposées en solution à l’interface entre le semiconducteur et l’isolant de grille. Ce phototransistor incorporé dans un inverseur a montré l’apparition d’un signal de sortie de 2V dû à l’application d’une lumière de 1050 nm de longueur d’onde et de 250 µw/cm2 de puissanceDetection of light in large wavelength range, from the UV to NIR, is got with high sensitivity by using the amplification of a field effect transistor and the ability of light detection in large range by CdSe and PbS quantum dots with different diameters. In the first part, a FET with ZnO nanowires active layer is fabricated. The light detection in UV-Vis range is insured thanks to CdSe QDs/RGO (Reduced Graphene Oxide) fragments decorating the surface of the ZnO nanowires RGO insures good transfer of photo-electrons induced by the light into the CdSe QDs towards ZnO. The responsivity, higher than 104 A/W at 350 nm, has been improved by 100 in 200-500 nm range by using RGO. In the second part, IR light detection has been insured by using PbS QDs embedded in N-type Organic FET using C60 film as active layer. Silver electrodes of this transistor and its SU8 photoresist gate insulator have been printed. QDs have been deposited in solution at the interface between the semiconducting layer and the gate insulator. This phototransistor has been used in an inverter. The output voltage of the inverter change by 2V under lighting with 1050 nm wavelength and 250 µW/cm2 power
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Rissi, Nathalia Cristina [UNESP]. "Micelas poliméricas contendo pontos quânticos a base de óxido de Zinco com superfície modificada para futura aplicação em diagnóstico e vetorização de fármacos." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/141449.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Nos últimos anos, é possível observar um grande interesse no desenvolvimento de sistemas multifuncionais direcionados ao diagnóstico e tratamento do câncer. Estes sistemas também conhecidos como “teranósticos” têm se mostrado interessantes, pois ampliam a capacidade de liberação prolongada de fármacos anticancerígenos em células específicas, além de proporcionar um monitoramento ótico através da luminescência de pontos quânticos. Diante deste contexto, o presente estudo teve como objetivo estabilizar os pontos quânticos a base de óxido de zinco (ZnO) em meio aquoso através da modificação de superfície com o 3-(Glycidyloxypropyl)trimethoxysilane (GPTMS) e também em meio orgânico através da modificação com o Hexadecyltrimethoxysilane (HTMS), permitindo assim a veiculação do mesmo em micelas poliméricas A ligação entre os pontos quânticos e as moléculas dos modificadores ocorreu através das reações de hidrólise e condensação, utilizando como catalisador básico o hidróxido de lítio. Esta reação conduziu a formação de uma camada de siloxano ao redor das nanopartículas e resultou nas ligações covalentes do tipo ZnO-Si-O. Ainda com o objetivo de aumentar a estabilidade do ZnO em meio orgânico e consequentemente suas propriedades luminescentes, foi sintetizado uma bicamada formada entre o Ácido Oleico (AO) e o HTMS. As modificações na superfície do ZnO foram confirmadas pelas técnicas de espectroscopia vibracional na região do infravermelho e também pela espectroscopia de fotoelétrons induzidos por raios-X. O comportamento ótico foi feito através da espectroscopia de absorção na região do UV-Vis. Com está técnica, identificou-se o comprimento de onda limite associado ao pico excitônico do ZnO e através do monitoramento deste pico, observou-se estabilidade em água por um período de 15 dias para a grande maioria das amostras de ZnO modificado pelo GPTMS e também para o ZnO modificado pelo HTMS e pela bicamada de AO/HTMS em clorofórmio. O tamanho final dos pontos quânticos foi analisado pela microscopia de transmissão eletrônica, apresentando um tamanho médio entre 3,5- 4nm para as amostras de ZnO modificado pelo GPTMS e de 4,5 nm para as amostras de ZnO modificado pelo HTMS e pela bicamada de AO/HTMS. Com a técnica de difração de raios-X, identificou-se os picos de difração correspondentes a uma estrutura cristalina do tipo Wurtzita. As medidas de fotoluminescência permitiu a obtenção de informações sobre a intensidade luminescente, assim como as cores emitidas dos pontos quânticos e demostraram a importância das modificações de superfície em relação ao aumento da intensidade luminescente. A veiculação do ZnO estáveis no meio orgânico em micelas poliméricas formadas pelo Pluronic F127 e Pluronic F68, foi realizada com sucesso. Este fato foi observado por meio dos espectros de absorção no UV-vis e também pelas medidas de fotoluminescência. Com a técnica de espalhamento de luz dinâmico, avaliou-se parâmetros relacionados com o tamanho e o índice de polidispersidade das micelas. O teste de citotoxicidade in vitro foi feita através do MTT e apresentou uma boa viabilidade celular para as linhagens celulares de queratinócito humano (HaCat) e de hepatoma humano (HepG2). A quantificação das células em que houve a internalização das micelas contendo os pontos quânticos hidrofóbicos como marcador foi feita através da citometria de fluxo. Diante dos resultados obtidos, conclui-se a existência de um potencial a ser explorado em relação ao ZnO modificado pelo GPTMS em aturar futuramente como sondas biológicas. Já as propriedades hidrofóbicas concedidas ao ZnO modificado pelo HTMS e pela bicamada formada entre o AO/HTMS permitiu a incorporação dos mesmos em sistemas micelares e tem como objetivo auxiliar na aplicação futura desses pontos quânticos através do desenvolvimento de sistemas teranósticos.
In recent years, it is possible to observe a growing interest in the development of multifunctional systems used, that can be used in the diagnosis and treatment of cancer These systems also known as " theranostic " and have gained considerable attention due to their capacity of release anticancer drugs into specific cells, besides to optical monitoring through quantum dots. In this context, the present study was aimed to stabilize the quantum dots of of ZnO in water by modifying with 3-(Glycidyloxypropyl)trimethoxysilane (GPTMS) with and organic medium.by modifying with Hexadecyltrimethoxysilane (HTMS), thus allowing them to be incorporated into polymeric micelles The binding between the quantum dots with the modifiers occurred by hydrolysis and condensation reaction under basic catalysis by lithium hydroxide, thus leading to the formation of siloxane layer and resulted in ZnO-Si-O covalent bond. In order to improve the stability of ZnO-QDs and consequently their photoluminescence properties, was synthesized a coating bilayer by OA and HTMS. The ZnO surface modification was confirmed by infrared spectroscopy and also by X-ray photoelectron spectroscopy. The optical behavior was performed by absorption spectroscopy in the UV-Vis region. With this technique was possible to identify the wavelength limit associated with the excitonic peak and by monitoring of this peak was observed a great stability during 15 days for almost all samples of ZnO modified by GPTMS in water and ZnO modified by HTMS and bilayer AO / HTMS in chloroform. The finale size of quantum dots was analyzed by transmission electron microscopy that showed an average size about 3,5- 4nm for the samples of znO modified by GPTMS, and 4,5 nm by HTMS and AO/HTMS bilayer. By X-ray diffraction, it was possible to identify through the diffraction peak a wurtzite structure. The photoluminescence measurements allowed to obtain information about luminescence intensity, as well as the emitted colors by quantum dots and demonstrated the importance of surface modifications in relation to increase of luminescence intensity. The placement of hydrophobic ZnO into polymeric micelles formed by Pluronic F127 and Pluronic F68 was successful. This fact can be observed by absorption spectroscopy in UV-vis and by photoluminescence measurements. With the dynamic light scattering, it was possible to observe the hydrodynamic size distribution and polydispersity index of the micelles. In vitro cytotoxicity assay was performed by MTT and showed a great cellular viability for human keratinocytes cells (HaCat) and for hepatocellular carcinoma cells (HepG2). The cellular internalization was performed by flow cytometry. Based on these results, it was concluded a potential to be explored in to ZnO modified by GPTMS to acting in the future as biological probes. The hydrophobic properties of ZnO modified by HTMS and the AO / HTMS bilayer allowed the incorporation in micellar systems and aims to assist in the implementation of these quantum dots through the development of systems theranostics.
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Sugunan, Abhilash. "Fabrication and Photoelectrochemical Applications of II-VI Semiconductor Nanomaterials." Doctoral thesis, KTH, Funktionella material, FNM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95410.
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In this work we investigated fabrication of semiconductor nanomaterials and evaluated their potential for photo-chemical and photovoltaic applications. We investigated different II-VI semiconductor nanomaterial systems; (i) ZnO oriented nanowire arrays non-epitaxially grown from a substrate; and (ii) colloidal CdE (E=Te,Se,S) quantum structures synthesized by solution-based thermal decomposition of organo-metallic precursors. We have studied the synthesis of vertically aligned ZnO nanowire arrays (NWA), by a wet chemical process on various substrates. We have extended this method wherein nanofibers of poly-L-lactide act as a substrate for the radially oriented growth of ZnO nanowires. By combining the large surface area and the flexibility of the PLLA-ZnO hierarchical nanostructure we have shown the proof-of-principle demonstration of a ‘continuous-flow’ water treatment system to decompose known organic pollutants in water, as well as render common waterborne bacteria non-viable. We have studied synthesis of colloidal quantum dots (QD), and show size, morphology and composition tailored nanocrystals for CdE (E=S, Se, Te) compositions. We have studied the influence of crystal growth habits of the nanocrtsyals on the final morphology. Furthermore we have synthesized core-shell, CdSe-CdS QDs with spherical and tetrahedral morphologies by varying the reaction conditions. We show that these core-shell quantum dots show quasi-type II characteristics, and demonstrate with I-V measurements, the spatial localization of the charge carriers in these hetero-nanocrystals. For this purpose, we developed hybrid materials consisting of the core-shell quantum dots with electron acceptors (ZnO nanowires) and hole acceptors (polymeric P3HT nanofibers). In addition we have also compared the synthesis reaction when carried out with conventional heating and microwave-mediated heating. We find that the reaction is enhanced, and the yield is qualitatively better when using microwave induced heating.QC 20120525
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Akca, Nazmiye Bihter. "Synthesis Of 2-aminopyrrole-3-carboxylates Via Zinc Perchlorate Mediated Annulation Of Alpha-cyano-gamma-ketoesters With Amines." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609715/index.pdf.
Full textAbstract:
2-Aminopyrrole-3-carboxylate derivatives are important starting materials for biologically active compounds like pyrrolotriazole, pyrrolotriazine so their synthese has great importance in the synthetic organic chemistry.
There are only two methods for the synthesis of 2-aminopyrrole-3-carboxylates in the literature. Therefore, there is a great need for the design and development of a new method for the synthesis of 2-aminopyrrole-3-carboxylates.
In this work, 2-aminopyrrole-3-carboxylate derivatives were synthesized starting from cyano acetic acid ethyl ester with a new method. In the first step, cyanoacetic acid ethyl ester was
alkylated with bromo acetone in the presence of NaH. Then, obtained gamma-ketoester was reacted with primary amines in the presence of catalytic amount of zincpechlorate (Zn(ClO4)2). As a result, 2-aminopyrrole-3-carboxylate derivatives were obtained. Cyanoacetic acid ethyl ester was also alkylated with various bromo acetophenone derivatives in the presence of DBU
(1,8-Diazabicycloundec-7-ene). As a result of these reactions, different gamma-ketoesters were obtained. The reaction of these gamma-ketoesters with primary amines in the presence of catalytic amount of Zn(ClO4)2 concluded with 2-aminopyrrole-3-carboxylate derivatives.
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Ozturk, Elif. "Copolymerisation Of Carbon Disulfide, Carbon Dioxide And Other Carbonic Acid Derivatives With Cyclic Ethers By Using Metal Xanthate Catalysts." Phd thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607227/index.pdf.
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The synthesis of high molecular weight copolymer of carbon disulphide (CS2) and propylene oxide (PO) has not reported in literature. In the present work, zinc isopropyl xanthate (Zn(Xt)2) was used as catalyst for the copolymerisation of PO and CS2 into high copolymer. However, the product can be fractionated into high and low molecular weight components. High molecular weight copolymer was rubbery products, but low molecular weight copolymers were oily products containing cyclic dithiocarbonates. Copolymers were characterized by elemental, end group analysis, DSC, TGA, GPC, Light Scattering, UV, IR, NMR spectroscopy, polarized microscopy and refractometry.
Copolymerization process was zeroth order with respect to monomers, and its non-terminated but suffered from several types of transfer reactions. As a result of transfer reactions S-(C=S)-S, O-(C=S)-O, O-(C=O)-O groups in the backbone of copolymer and SH groups at the chain terminals and cyclic dithiocarbonates are formed. Apart from SH groups, OH and double bonds were found and their amounts were
determined at the chain terminals. Copolymers with high mole fractions of PO units (F1) in the copolymer are crystallized in the shape of Malta’
s Cross. Melting points of products were obtained from DSC. The F1 values are calculated from elemental analysis as well as zeroth order rate constants and from melting point of the crystals. All three results were in close agreement and changed between 0.9 &
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0.7. However, these ratios depend on reaction conditions (temperature, catalyst and monomer concentrations, time and dielectric constant of reaction medium). A mechanism for coordination-copolymerization on the basis of above observation was proposed.
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Sibony, Jonas. "De l'analysibilité des racines de l'hébreu biblique." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2013. http://tel.archives-ouvertes.fr/tel-00935550.
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Notre étude s'inscrit dans le cadre de la théorie des matrices et des étymons (TME), principalement élaborée par G. Bohas (1997, 2000), G. Bohas et M. Dat (2007) et G. Bohas et A. Saguer (2012). Ce nouvel outil propose une réorganisation du lexique des langues sémitiques non plus sur la base de phonèmes mais de traits phonétiques. Cette perspective mène à contester le caractère primitif de la notion de racine triconsonantique développée par les grammairiens arabes du Moyen-Âge. De plus, la TME permet de rendre compte d'un certain nombre de régularités observées dans le lexique, telles que les liens phonético-sémantiques existants entre certains radicaux, l'aspect mimétique de la structure du signe, la polysémie des racines trilitères, etc. Notre thèse traite dans ce cadre du vocabulaire de l'hébreu biblique et se présente en trois parties. Dans un premier temps est donnée une description complète du fonctionnement de la théorie, suit un développement du vocabulaire de sept champs notionnels contraints par un cadre phonétique stable puis nous proposons un dictionnaire présentant une réorganisation totale du lexique hébraïque ancien sur la base d'étymons bilitères.
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Chiu, Kuei-Lin, and 邱奎霖. "Modeling and high pressure experiment of CdSe/ZnS Colloidal QDs." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/86104025076490648291.
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碩士國立交通大學
物理研究所
94
In this thesis we study the Raman, PL and time resolve spectrum of the colloid core/shell CdSe/ZnS quantum dot under high pressure. From our experiment result, we want to find out the curve of the energy band gap of QD versus pressure, and the possible structure of QDs under high pressure. Finally, we also want to verify the quantum optic theorem by our time resolve experiment.
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Permadi, Adi, and 王耀明. "The Preparation of CuInS2/ZnS QDs as Labeling Tumor Cells and Development of Their Usefulness." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/65jk32.
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博士國立臺灣科技大學
化學工程系
105
Abstract . Quantum dots (QDs), which are colloidal nanocrsytals offer many functions such as biological labelling, drug delivery, photodynamic therapy, nanodiagnostic, and photonic devices. Because of displaying a bright luminescence and offering the possibility to tune their size and emission wavelength, biological labeling of QDs is one of the fastest moving field of nanomaterials today. Due to alleged toxicity and environmental concern, developing CuInS2/ZnS QDs as low toxic nanomaterials for labeling cancer cells became important. In this work, CuInS2/ZnS QDs were made by the method of hot colloidal synthesis. QDs are usually covered by a layer of hydrophobic molecules. Thus, surface modification such as coating or conjugating hydrophilic or amphiphilic molecules is needed to convert QDs from organic to aqueous solution for biological application. Here, CuInS2/ZnS QDs was coated with Poly(ethylene glycol) methacrylate (PEGMA) which allows for transferring hydrophibically caped nanocrystals from organic to aqueous solution. The PEGMA coated CuInS2/ZnS showed stable emission for up to 3 weeks and labeled human liver carcinoma (HepG2) tumor cells with red luminescence were clearly visible. In this thesis, CuInS2/ZnS QDs in oil phase can be directly transferred into water phase via sonication without any additional surfactant, capping ligand, or surface coating with polymers. Further improvement, CuInS2/ZnS QDs dispersion in water directly prepared without any non-polar solvent was revealed. Finally, HepG2 tumor cells confocal images stained with water-dispersed CuInS2/ZnS QDs are showing. In vitro evaluation has proven that the the transferred QDs are low-toxic along with being an efficient labelling agent to HepG2 tumor cells. Furthermore Utility of poly(maleic anhydride-alt-1-octadecene) as capping ligand for CuInS2/ZnS QD and bioconjugation of Amine - CuInS2/ZnS QDs was demonstrated. In Addition the exploration of potential of CuInS2/ZnS QDs in nanogel was showed Keywords : CuInS2/ZnS, Quantum Dots, Ultrasonic, tumor cells Thesis supervisor : Jia Yaw-Chang Title : Professor of Nano Chemistry
Book chapters on the topic "ZnS QDs"
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Miguel, Ana Sofia, Christopher Maycock, and Abel Oliva. "Synthesis and Functionalization of CdSe/ZnS QDs Using the Successive Ion Layer Adsorption Reaction and Mercaptopropionic Acid Phase Transfer Methods." In Nanoparticles in Biology and Medicine, 143–55. Totowa, NJ: Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-953-2_10.
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Huang, Kangqiang, Li Chen, Kun Liu, and Jianwen Xiong. "The Best Parameters of the Vivo Destruction of HL60 Cells by the Use of QDs (CdSe-ZnS) Based on Photodynamic Therapy." In Advances in Intelligent and Soft Computing, 713–19. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29637-6_96.
Full textConference papers on the topic "ZnS QDs"
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Dennis, Allison M., and Gang Bao. "Fluorescence Resonance Energy Transfer Between a Fluorescent Protein and Commercially Available Quantum Dots." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192927.
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Semi-conductor quantum dots (QDs) are exceptionally bright fluorescent emitters that have garnered much attention over the past decade as an emerging tool for biomedical investigations. QDs offer several advantages over organic fluorophores, including up to 1,000-fold higher brightness than most organic fluorophores, very photostable, the “tunable emission” allowing for desired emission spectrum, and the ability to excite almost all QDs by a single (UV) wavelength [1,2]. The QDs typically used in the visible wavelength range are CdSe/ZnS core-shell nanoparticles; the CdSe center confers the particle its unique optical properties, while the ZnS shell serves as a passivation layer, protecting the core from oxidation and enhancing the quantum yield. In addition, an organic coating is necessary in order to confer water-solubility to the QD for biological studies [1,2].
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Cizmeciyan, M. Natali, Guncem Ozgun Eren, Alireza Khoshzaban, Sedat Nizamoglu, and Mehmet Burcin Unlu. "Effect of ZnS Shell Thickness in InP Quantum Dots for Photo-acoustic Wave Generation." In Advanced Solid State Lasers. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/assl.2022.jm4a.19.
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Photo-acoustic spectroscopy technique showed that increasing the ZnS thick- ness from one to five layers and decreasing PLQY from 30% to 9% did not influence the amplitude of emitted acoustic waves for InP/ZnS QDs.
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Kim, S. M., K. S. Hong, K. Kyhm, Ho-Soon Yang, Jisoon Ihm, and Hyeonsik Cheong. "Energy relaxation processes in CdSe∕ZnS QDs." In PHYSICS OF SEMICONDUCTORS: 30th International Conference on the Physics of Semiconductors. AIP, 2011. http://dx.doi.org/10.1063/1.3666490.
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Wang, Jun, and Rui Pan. "Ultra-high responsivity graphene-CIS/ZnS QDs hybrid photodetector." In Optoelectronic Materials and Devices for Sensing and Imaging, edited by Mingbo Pu, Xue Feng, Yadong Jiang, Xiong Li, Xiaoliang Ma, and Bernard Kippelen. SPIE, 2019. http://dx.doi.org/10.1117/12.2506576.
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Kuznetsova, Yulia V., Ivan D. Popov, and Andrey A. Rempel. "Synthesis of highly luminescent ZnS QDs in aqueous solution." In THE 2ND INTERNATIONAL CONFERENCE ON PHYSICAL INSTRUMENTATION AND ADVANCED MATERIALS 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0032224.
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Qin, Zhijie, Qiulin Yue, and Xinli Liu. "Fluorescent ZnCdSe/ZnS QDs probes for sensitive copper (II) detection." In 2018 7th International Conference on Energy, Environment and Sustainable Development (ICEESD 2018). Paris, France: Atlantis Press, 2018. http://dx.doi.org/10.2991/iceesd-18.2018.222.
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Salverson, Lynsey A. M., Nader Saniei, Mel Mendelson, and Michelle Lum. "An Engineering Approach Investigating the Uptake and Phytotoxicity of One Type of Engineered Nanoparticle (CdSe/ZnS Quantum Dots) by Solanum Lycopersicum." In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14032.
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The novel and extraordinary physiochemical properties of engineered nanoparticles (ENPs) is certain, yet, at the same time, their unique characteristics raise growing concerns regarding potentially adverse effects on biological and ecological systems. It is becoming increasingly evident, that before the full potential of nanotechnology can be realized, standardized characterization of ENPs behavior, fate, and their effects in the ecosystem are essential, to ensure the safe manufacturing and use of ENP products. Otherwise, the promise of such extraordinary advancements may find itself limited to applications such as electronics, and sporting equipments, industries in which it currently resides. The current toxicity profile of engineered nanomaterials is not only preliminary, but highly variable amongst researchers. Emphasizing the great need to develop a highly organized, efficient, and precise approach to assess the hazardous potential ENPs may pose, and address the safety concerns surrounding and limiting nanotechnology. In response to such concerns, the present study took an engineering approach, in an otherwise traditionally viewed discipline, to assess the potential impact of engineered nanoparticles on tomato (Solanum lycopersicum) seedlings, by implementing a full factorial design of experiment (FDOE) in an effort to identify what factors, and their interactions, have a significant (p ≤ 0.05) effect on root and shoot elongation, and if any observed effects are a result of particle uptake, evaluated via fluorescence microscopy imaging. Therefore, the goal of our study was to design and implement an efficient, effective, and precise method to assess the effect of one type of ENP, water-soluble CdSe/ZnS quantum dots, using Solanum lycopersicum as our model organism, one of 10 species recommended by the Unites States Environmental Protection Agency (US EPA) for use in phytotoxicity studies, via a methodology we believe novel to nanotechnology. By implementing factorial experimental design methodologies, not only are we efficiently identifying the factors that affect phytotoxicity, we are providing, for the first time to our knowledge, the first scientific data to report the significant interaction effects between the factors responsible for ENP toxicity. Water soluble (MUA) CdSe/ZnS quantum dots used in our study had a negative influence on root and shoot lengths of tomato seeds exposed for 3 and 6 days. The observed influence depended on (MUA) CdSe/ZnS concentration and QD exposure time. The importance of the factor effects were examined via analysis of variance (ANOVA), t-tests, confidence intervals, and normal plot statistical analyses. The findings concluded that factors B, C, and the BC-interaction (CdSe/ZnS: Exposure time, concentration, and exposure time–concentration interaction) significantly (p ≤ 0.05) affected root and shoot lengths of tomato seedlings. Thus, factors A, AB, AC, and ABC (CdSe/ZnS QD: Size, size–concentration, size-exposure time, and size-concentration-exposure time interactions) were not found to have a significant effect on root and shoot lengths of tomato seedlings, and ultimately eliminated from our model. After analyzing the interaction plots, it became evident that low percentages of root reduction are obtained at low concentration levels for short lengths of time; thus, to obtain the least amount of phytotoxic effects one would set factors B (concentration) and C (exposure time) to their low levels, 125 mg/L for 3 days, respectively. Alternatively, high percentages of root reduction are obtained at high concentration levels for long lengths of time; thus, to obtain the greatest phytotoxic effect one would set factors B and C to their high levels, 1000 mg/L for 6 days, respectively. This indicates that as exposure time increases, root reduction increases; thus, phytotoxicity increases. Since our study attempted to realize which factors minimize phytotoxicity effects of one type of ENP, these findings suggest that to minimize phytotoxicity effects (i.e. maximize root length or minimize percent of root reduction) of (MUA) CdSe/ZnS QDs on tomato seeds, set factors B and C (QD concentration and exposure time) to their low levels; that is, expose tomato seeds to 125 mg/L of QD solution for a maximum of 3 days. These settings will yield the least amount of root reduction (5.15%) and; thus, phytotoxicity effects will be minimized. With regard to tomato roots ability to uptake MUA QDs, our results contribute to the literature by reporting uptake possible. Although we did see particles inside the root, it was sporadic and difficult to quantify. As to whether it was intracellular (within the cell) or intercellular (in the spaces between the cells, i.e., outside the cells) we could not conclude with certainty, although we suspect the QDs were intercellular. Thus, we highly recommend future experiments involving cross sections and more in-depth microscopy imaging. Additionally, although the results of our experiment failed to support that particle size (t = 2.13; d.f. = 1; p = 0.065) or the particle size-exposure time interaction (t = 2.17; d.f. = 1; p = 0.062) had a significant effect on root and shoot lengths of tomato seedlings, due to the small p-value associated with both test statistics, it is our belief that particle size and the particle size-exposure time interaction may, in fact, be a real effect; thus, further investigation is recommended.
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Chu, Cheng-Shane, and Cheng-Yi Lin. "Ratiometric optical urea sensor based on CdSe/ZnS QDs and Rh110 doped in polymer matrix." In Optical Sensors. Washington, D.C.: OSA, 2020. http://dx.doi.org/10.1364/sensors.2020.stu5d.4.
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Duong, Hong Dinh, Jee Won Lee, and Jong Il Rhee. "Enhancement of singlet oxygen production based on FRET between Coumarin tri-compound and CdSe/ZnS QDs." In SPIE NanoScience + Engineering, edited by Hooman Mohseni, Massoud H. Agahi, and Manijeh Razeghi. SPIE, 2014. http://dx.doi.org/10.1117/12.2060346.
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Xiao, Xiangtian, Haodong Tang, Tianqi Zhang, Wei Chen, Wanli Chen, Junjie Hao, Rui Wang, and Kai Wang. "Utilizing CdSe/ZnS core/shell QDs to improve the modulation bandwidth of WLED for visible light communication." In 2016 17th International Conference on Electronic Packaging Technology (ICEPT). IEEE, 2016. http://dx.doi.org/10.1109/icept.2016.7583352.
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