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Nwahara N, Britton J, Nyokong T. Improving singlet oxygen generating abilities of phthalocyanines: aluminum tetrasulfonated phthalocyanine in the presence of graphene quantum dots and folic acid. J COORD CHEM 2017. [DOI: 10.1080/00958972.2017.1313975] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Nwaji N, Mack J, Britton J, Nyokong T. Synthesis, photophysical and nonlinear optical properties of a series of ball-type phthalocyanines in solution and thin films. NEW J CHEM 2017. [DOI: 10.1039/c6nj03662g] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Ball-type phthalocyanines containing heavy central metals show enhanced nonlinear optical behaviour in solution or when embedded in polymer thin films. Time dependent density functional theory (TD-DFT) calculations were used to explain the spectra.
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Oluwole DO, Yagodin AV, Britton J, Martynov AG, Gorbunova YG, Tsivadze AY, Nyokong T. Optical limiters with improved performance based on nanoconjugates of thiol substituted phthalocyanine with CdSe quantum dots and Ag nanoparticles. Dalton Trans 2017; 46:16190-16198. [DOI: 10.1039/c7dt03867d] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Grafting of thiolated phthalocyanine onto quantum dots and nanoparticles provided conjugates with prominent optical limiting.
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Gounden D, Ngubeni GN, Louzada MS, Khene S, Britton J, Nombona N. Synthesis, spectroscopic and DFT Characterization of 4β-(4-tert-Butylphenoxy)phthalocyanine positional isomers for non-linear optical absorption. SOUTH AFRICAN JOURNAL OF CHEMISTRY 2017. [DOI: 10.17159/0379-4350/2017/v70a8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Britton J, Martynov AG, Oluwole DO, Gorbunova YG, Tsivadze AY, Nyokong T. Improvement of nonlinear optical properties of phthalocyanine bearing diethyleneglycole chains: Influence of symmetry lowering vs. heavy atom effect. J PORPHYR PHTHALOCYA 2016. [DOI: 10.1142/s1088424616501042] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This paper reports the successful synthesis of the low symmetry phthalocyanines: metal-free 2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-[Formula: see text]-butoxyphthalocyanine 1H[Formula: see text] and its zinc complex 1Zn along with their nonlinear optical (NLO) behavior in solution and in thin films. 1H NMR investigations evidenced of higher dissymmetry of electronic density in 1H[Formula: see text] in comparison with 1Zn. This dissymmetry is responsible for unusually higher values of Im[[Formula: see text]]/[Formula: see text], [Formula: see text], and [Formula: see text] for 1H[Formula: see text]in contrast to 1Zn, where the notable effect of heavy-metal enhancement of ISC was expected. Both compounds showed Im[[Formula: see text]]/[Formula: see text] values of the order of 10[Formula: see text] in chloroform which are higher in comparison to the symmetrical octabutoxyphthalocyanine H2[(BuO)8Pc]. NLO properties of 1H[Formula: see text] were improved via its incorporation into polycarbonate polymeric matrix together with CdSe@CdS-TOPO quantum dots. In such composite the value of Im[[Formula: see text]]/[Formula: see text] was almost three times higher in comparison with 1H[Formula: see text] solution in chloroform. The obtained composites are expected to be perspective components of optical materials, capable of protection against strong light irradiation.
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Managa M, Mkhize S, Britton J, Prinsloo E, Nyokong T. Synthesis and dark toxicity of 5-(4-carboxyphenyl)-10,15,20-tris(phenyl)-porphyrinato chlorido gallium(III) when conjugated to δ-aminolevulinic acid. J COORD CHEM 2016. [DOI: 10.1080/00958972.2016.1223292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Managa M, Britton J, Prinsloo E, Nyokong T. Effects of pluronic silica nanoparticles on the photophysical and photodynamic therapy behavior of triphenyl-p-phenoxy benzoic acid metalloporphyrins. J COORD CHEM 2016. [DOI: 10.1080/00958972.2016.1236372] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Achadu OJ, Britton J, Nyokong T. Graphene Quantum Dots Functionalized with 4-Amino-2, 2, 6, 6-Tetramethylpiperidine-N-Oxide as Fluorescence “Turn-ON” Nanosensors. J Fluoresc 2016; 26:2199-2212. [DOI: 10.1007/s10895-016-1916-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/26/2016] [Indexed: 11/29/2022]
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Faulkner D, Britton J, Eng S, Del Galdo F, Stark D, Buch M. FRI0272 Evaluation of Bleomycin Induced Raynaud's Phenomenon and Systemic Sclerosis Vasculopathy in Germ Cell Tumour Patients. Ann Rheum Dis 2016. [DOI: 10.1136/annrheumdis-2016-eular.1826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Kempgens P, Britton J. Powder-XRD and (14) N magic angle-spinning solid-state NMR spectroscopy of some metal nitrides. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2016; 54:371-376. [PMID: 26687421 DOI: 10.1002/mrc.4395] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 11/02/2015] [Accepted: 11/10/2015] [Indexed: 06/05/2023]
Abstract
Some metal nitrides (TiN, ZrN, InN, GaN, Ca3 N2 , Mg3 N2 , and Ge3 N4 ) have been studied by powder X-ray diffraction (XRD) and (14) N magic angle-spinning (MAS) solid-state NMR spectroscopy. For Ca3 N2 , Mg3 N2 , and Ge3 N4 , no (14) N NMR signal was observed. Low speed (νr = 2 kHz for TiN, ZrN, and GaN; νr = 1 kHz for InN) and 'high speed' (νr = 15 kHz for TiN; νr = 5 kHz for ZrN; νr = 10 kHz for InN and GaN) MAS NMR experiments were performed. For TiN, ZrN, InN, and GaN, powder-XRD was used to identify the phases present in each sample. The number of peaks observed for each sample in their (14) N MAS solid-state NMR spectrum matches perfectly well with the number of nitrogen-containing phases identified by powder-XRD. The (14) N MAS solid-state NMR spectra are symmetric and dominated by the quadrupolar interaction. The envelopes of the spinning sidebands manifold are Lorentzian, and it is concluded that there is a distribution of the quadrupolar coupling constants Qcc 's arising from structural defects in the compounds studied.
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Minnis P, O’Meara R, Kane H, Zaffaroni A, O’Dea F, Britton J, Caulfield B, Donnelly SC. P50 Predicting readmission following exacerbation of COPD using a non-contact sensor – A Proof of Concept Study. Thorax 2015. [DOI: 10.1136/thoraxjnl-2015-207770.187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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D’Souza S, Mashazi P, Britton J, Nyokong T. Effects of differently shaped silver nanoparticles on the photophysics of pyridylsulfanyl-substituted phthalocyanines. Polyhedron 2015. [DOI: 10.1016/j.poly.2015.06.038] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Eastwood B, Dockrell M, Arnott D, Britton J, Cheeseman H, Jarvis M, McNeill A. Electronic cigarette use in young people in Great Britain 2013–2014. Public Health 2015; 129:1150-6. [DOI: 10.1016/j.puhe.2015.07.009] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 07/06/2015] [Accepted: 07/13/2015] [Indexed: 11/27/2022]
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Lettieri G, Abignano G, Eng S, Britton J, Ridgway J, Evans R, Rathbone A, O'Connor P, Emery P, Buch M, Del Galdo F. FRI0466 Digital Artery Flow Index by Non-Contrast Magnetic Resonance Angiography of the Hand: A Quantitative Outcome Measure of Fibroproliferative Vasculopathy in Raynaud's Phenomenon of Scleroderma. Ann Rheum Dis 2015. [DOI: 10.1136/annrheumdis-2015-eular.6045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Mkhize C, Britton J, Mack J, Nyokong T. Optical limiting and singlet oxygen generation properties of phosphorus triazatetrabenzcorroles. J PORPHYR PHTHALOCYA 2015. [DOI: 10.1142/s1088424614501065] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Novel phosphorus triazatetrabenzcorrole (TBC) tetrasubstituted at the α- and β-positions of the peripheral fused benzene rings with t-butylphenoxy substituents have been prepared and characterized. The effect of the substituents on the electronic structures and optical properties is investigated with TD-DFT calculations and MCD spectroscopy. The optical limiting properties have been investigated to examine whether the lower symmetry that results from the direct pyrrole–pyrrole bond and hence the permanent dipole moment that is introduced result in higher safety thresholds, relative to the values that have been reported for phthalocyanines. The suitability of the compounds for singlet oxygen applications has also been examined.
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Amberbir A, Medhin G, Abegaz WE, Hanlon C, Robinson K, Fogarty A, Britton J, Venn A, Davey G. Exposure to Helicobacter pylori infection in early childhood and the risk of allergic disease and atopic sensitization: a longitudinal birth cohort study. Clin Exp Allergy 2014; 44:563-71. [PMID: 24528371 PMCID: PMC4164268 DOI: 10.1111/cea.12289] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 12/21/2013] [Accepted: 01/12/2014] [Indexed: 12/21/2022]
Abstract
Background An inverse relation between Helicobacter pylori infection and allergic disease has been reported by a range of independent epidemiological studies, but evidence from longitudinal studies is scarce. Objective We have investigated the effects of H. pylori infection on the incidence and prevalence of allergic diseases and sensitization in a low-income birth cohort. Methods In 2005/2006, a population-based birth cohort was established in Butajira, Ethiopia, and the 1006 singleton babies born were followed up at ages 1, 3, and 5. Symptoms of allergic disease were collected using the ISAAC questionnaire, allergen skin tests performed, and stool samples analysed for H. pylori antigen and geohelminths. Multiple logistic regression was used to determine the independent effects of H. pylori measured at age 3 on the incidence of each outcome between ages 3 and 5 years (in those without the outcome at age 3), controlling for potential confounders, and to additionally assess cross-sectional associations. Results A total of 863 children were followed up to age 5. H. pylori infection was found in 25% of the children at both ages 3 and 5, in 21% at age 5 but not 3, and in 17% at age 3 but not at age 5. H. pylori infection at age 3 was significantly associated with a decreased risk of incident eczema between ages 3 and 5 (adjusted OR, 95% CI, 0.31; 0.10–0.94, P = 0.02). Cross-sectionally at age 5, H. pylori infection was inversely associated with skin sensitization (adjusted OR, 95% CI, 0.26; 0.07–0.92, P = 0.02). Conclusion and clinical relevance These findings provide further evidence to suggest that early-life exposure to H. pylori may play a protective role in the development of allergy.
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Szatkowski L, Murray R, Hubbard R, Agrawal S, Huang Y, Britton J. Prevalence of smoking among patients treated in NHS hospitals in England in 2010/2011: a national audit: Table 1. Thorax 2014; 70:498-500. [DOI: 10.1136/thoraxjnl-2014-206285] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 09/25/2014] [Indexed: 11/04/2022]
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Szatkowski L, Taylor J, Taylor A, Lewis S, McNeill A, Britton J, Jones L, Bauld L, Parrott S, Wu Q, Bains M. OP24 Development and evaluation of a novel intervention providing insight into the tobacco industry to prevent the uptake of smoking in school-aged children. Br J Soc Med 2014. [DOI: 10.1136/jech-2014-204726.27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Turner D, Britton J, Tassell N, Bird D, Goulden V. Safety of patients fitted with electronic active artificial implanted devices in ultraviolet treatment cubicles. Br J Dermatol 2014; 171:197-8. [PMID: 24641264 DOI: 10.1111/bjd.12903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Datta R, Munson CD, Niemack MD, McMahon JJ, Britton J, Wollack EJ, Beall J, Devlin MJ, Fowler J, Gallardo P, Hubmayr J, Irwin K, Newburgh L, Nibarger JP, Page L, Quijada MA, Schmitt BL, Staggs ST, Thornton R, Zhang L. Large-aperture wide-bandwidth antireflection-coated silicon lenses for millimeter wavelengths. APPLIED OPTICS 2013; 52:8747-8758. [PMID: 24513939 DOI: 10.1364/ao.52.008747] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 10/25/2013] [Indexed: 06/03/2023]
Abstract
The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n=3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30° with low cross polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.
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Britton J, Durmuş M, Chauke V, Nyokong T. Poly methyl methacrylate films containing metallophthalocyanines in the presence of CdTe quantum dots: Non-linear optical behaviour and triplet state lifetimes. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2013.09.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Venero-Fernández SJ, Suárez-Medina R, Mora-Faife EC, García-García G, Valle-Infante I, Gómez-Marrero L, Abreu-Suárez G, González-Valdez J, Fabró-Ortiz DD, Fundora-Hernández H, Venn A, Britton J, Fogarty AW. Risk factors for wheezing in infants born in Cuba. QJM 2013; 106:1023-9. [PMID: 23824939 PMCID: PMC3808789 DOI: 10.1093/qjmed/hct143] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Cuba is a unique country, and despite limited economic development, has an excellent health system. However, the prevalence of asthma symptoms in children in Havana, Cuba, is unusually high. AIM As early life exposures are critical to the aetiology of asthma, we have studied environmental influences on the risk of wheezing in Cuban infants. DESIGN Cross-sectional study. METHODS A random sample of 2032 children aged 12-15 months living in Havana was selected for inclusion in the cohort. Data were collected using questionnaires administered by researchers. RESULTS Of 2032 infants invited to participate, 1956 (96%) infants provided data. The prevalence of any wheeze was 45%, severe wheeze requiring use of emergency services was 30% and recurrent wheeze on three or more occasions was 20%. The largest adjusted risk factors for any wheeze were presence of eczema [odds ratio (OR) 2.09; 95% confidence interval (CI) 1.48-2.94], family history of asthma (OR 2.05; 95% CI 1.60-2.62), poor ventilation in the house (OR 1.99; 95% CI 1.48-2.67), attendance at nursery (OR 1.78; 95% CI 1.24-2.57), male sex (OR1.52; 95% CI 1.19-1.96) and the number of smokers in the house (P < 0.03 for trend), OR 1.64 (95% CI 1.17-2.31) for three or more smokers in the house compared to no smokers in the household. CONCLUSION We have identified several risk factors for any wheeze in young infants living in modern day Cuba. As the prevalence of smoking in the house is high (51%), intervention studies are required to determine effective strategies to improve infant health.
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Manouchehrinia A, Webston M, Britton J, Constantinescu C. Impact of tobacco smoking on mortality and life expectancy in multiple sclerosis patients. J Neurol Sci 2013. [DOI: 10.1016/j.jns.2013.07.1313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Britton J, Antunes E, Nyokong T. Synthesis and nonlinear optical examination of 3(4),15(16)-Bis-(4-tert-butyl-phenoxy)-10,22-diaminohemiporphyrazinato chloroindium. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2013.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Britton J, Durmuş M, Khene S, Chauke V, Nyokong T. Third order nonlinear optical properties of phthalocyanines in the presence nanomaterials and in polymer thin films. J PORPHYR PHTHALOCYA 2013. [DOI: 10.1142/s108842461350003x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Third order nonlinear optical properties were determined for phthalocyanine complexes 1–10 containing In , Ga and Zn central metals and tetra- or octa-substituted with benzyloxyphenoxy, phenoxy, tert-butylphenoxy and amino groups at peripheral or non-peripheral positions. The phthalocyanines were embedded in poly (methyl methacrylate) polymer in the presence of CdTe quantum dots. All complexes 1–10 were studied in the presence of CdTe quantum dots and embedded in poly (methyl methacrylate) to form thin films. Complex 3 tetrasubstituted with tert-butylphenoxy groups at non-peripheral positions was also studied in the presence of CdS , CdSe quantum dots, fullerenes, single walled carbon nanotubes. Third order nonlinear optical parameters generally increase for Pcs in the presence of CdTe quantum dots.
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