Elimination of fluorescence intensity difference in orientation determination of single molecules by highly focused generalized cylindrical vector beams

Water-soluble fluorescent carbon dots (CDs) were synthesized by a hydrothermal method using citric acid as the carbon source and ethylenediamine as the nitrogen source. The repeated and scale-up synthetic experiments were carried out to explore the feasibility of macroscopic preparation of CDs. The CDs/Fe3+ composite was prepared by the interaction of the CDs solution and Fe3+ solution. The optical properties, pH dependence and stability behavior of CDs or the CDs/Fe3+ composite were studied by ultraviolet spectroscopy and fluorescence spectroscopy. Following the principles of fluorescence quenching after the addition of Fe3+ and then the fluorescence recovery after the addition of asorbic acid, the fluorescence intensity of the carbon dots was measured at λex = 360 nm, λem = 460 nm. The content of ascorbic acid was calculated by quantitative analysis of the changing fluorescence intensity. The CDs/Fe3+ composite was applied to the determination of different active molecules, and it was found that the composite had specific recognition of ascorbic acid and showed an excellent linear relationship in 5.0–350.0 μmol·L−1. Moreover, the detection limit was 3.11 μmol·L−1. Satisfactory results were achieved when the method was applied to the ascorbic acid determination in jujube fruit. The fluorescent carbon dots composites prepared in this study may have broad application prospects in a rapid, sensitive and trace determination of ascorbic acid content during food processing.

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Feasibility of Extracting Velocity Distribution in Choriocapillaris in Human Eyes from ICG Dye Angiograms

Journal of Biomechanical Engineering ◽

10.1115/1.2165692 ◽

2005 ◽

Vol 128 (2) ◽

pp. 203-209 ◽

Cited By ~ 10

Author(s):

L. Zhu ◽

Y. Zheng ◽

C. H. von Kerczek ◽

L. D. T. Topoleski ◽

R. W. Flower

Keyword(s):

Velocity Distribution ◽

Fluorescence Intensity ◽

Conversion Factor ◽

Blood Velocity ◽

New Approach ◽

Pixel Location ◽

Choroidal Vasculature ◽

Dye Fluorescence ◽

Human Eyes

Indocyanine green (ICG) dye angiography has been used by ophthalmologists for routine examination of the choroidal vasculature in human eyes for more than 20years. In this study, a new approach is developed to extract information from ICG dye angiograms about blood velocity distribution in the choriocapillaris and its feeding blood vessels. ICG dye fluorescence intensity rise and decay curves are constructed for each pixel location in each image of the choriocapillaris in an ICG angiogram. It is shown that at each instant of time the magnitude of the local instantaneous dye velocity in the choriocapillaris is proportional to both the slope of the ICG dye fluorescence intensity curve and the dye concentration. This approach leads to determination of the absolute value of blood velocity in the choriocapillaris, assuming an appropriate scaling, or conversion factor can be determined. It also enables comparison of velocities in different regions of the choriocapillaris, since the conversion factor is independent of the vessel location. The computer algorithm developed in this study can be used in clinical applications for diagnostic purposes and for assessment of the efficacy of laser therapy in human eyes.

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Determination of Polyhexamethylene Biguanide Hydrochloride Using a Lactone-Rhodamine B-Based Fluorescence Optode

Molecules ◽

10.3390/molecules25020262 ◽

2020 ◽

Vol 25 (2) ◽

pp. 262

Author(s):

Akane Funaki ◽

Yuta Horikoshi ◽

Teruyuki Kobayashi ◽

Takashi Masadome

Keyword(s):

Fluorescence Intensity ◽

Sodium Salt ◽

Contact Lens ◽

Rhodamine B ◽

Determination Method ◽

Polyhexamethylene Biguanide ◽

Poly Vinyl Chloride ◽

Nitrophenyl Octyl Ether ◽

Optode Membrane

A new determination method for polyhexamethylene biguanide hydrochloride (PHMB) using a lactone-rhodamine B (L-RB) based fluorescence optode has been developed. The optode membrane consists of 2-nitrophenyl octyl ether as a plasticizer, L-RB, and poly (vinyl chloride). The optode responds to tetrakis (4-fluorophenyl) borate, sodium salt (NaTPBF) in the μM range. The fluorescence intensity of the L-RB film for PHMB solution containing 20 μM NaTPBF decreased linearly as the concentration of the PHMB solution increased in the concentration range from 0 to 8.0 μM, which shows that PHMB with a concentration range of 0 to 8.0 μM is determined by the L-RB film optode. The concentration of PHMB in the contact lens detergents by the proposed method was in accord with its nominal concentration.

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Light Figures of Single Crystals of Tetragonal Tin and the Determination of Their Crystal Orientations by the Light-Figure Method, Part III. Orientation Determination by the Light-Figure Method

Journal of the Japan Institute of Metals and Materials ◽

10.2320/jinstmet1952.17.3_113 ◽

1953 ◽

Vol 17 (3) ◽

pp. 113-118

Author(s):

Mikio Yamamoto ◽

Jirô Watanabé

Keyword(s):

Single Crystals ◽

Crystal Orientations ◽

Orientation Determination

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Spectrofluorometric determination of nicardipine, nifedipine and isradipine in pharmaceutical preparations and biological fluids

Open Chemistry ◽

10.2478/s11532-008-0011-x ◽

2008 ◽

Vol 6 (2) ◽

pp. 222-228 ◽

Cited By ~ 10

Author(s):

Sheikha Al-Ghannam ◽

Abeer Al-Olyan

Keyword(s):

Fluorescence Intensity ◽

Reaction Pathway ◽

Biological Fluids ◽

Sodium Dodecyl ◽

Pharmaceutical Preparations ◽

Reduction Reaction ◽

Factors Affecting ◽

Plasma And Urine Samples

AbstractA simple and highly sensitive spectrofluorometric method was developed for the determination of some 1,4-dihydropyridine compounds namely, nicardipine, nifedipine and isradipine in pharmaceutical preparations and biological fluids. The method is based on the reduction of nicardipine, nifedipine and isradipine with Zn/HCl and measuring the fluorescence intensity obtained (λem/λex) at 460/364, 450/393 and 446/360 nm, respectively. The factors affecting the development of the fluorophore and its stability were studied and optimized. The effect of some surfactants such as β-cyclodextrin (βCD), carboxymethylcelullose (CMC), sodium dodecyl sulphate (SDS) and triton X-100, on the fluorescence intensity was studied. The fluorescence intensity-concentration plots of nicardipine, nifedipine and isradipine were rectilinear over the ranges 0.4–6.0, 0.2–4.0 and 0.1–9.0 μg ml−1 with detection limits of 0.0028, 0.017 and 0.016 μg ml−1, respectively. The proposed method was successfully applied to commercial tablets containing the compounds; the percentage recovery agreed well with those obtained using the official methods. The method was further extended to the in vitro determination of the compounds in spiked human plasma and urine samples. A proposal of the reduction reaction pathway was postulated.

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