scholarly journals A Rich Gallery of Carbon Dots based Photoluminescent Suspensions and Powders Derived by Citric acid/urea

2021 ◽  
Author(s):  
Antonios Kelarakis ◽  
Marta Krysmann ◽  
Joanna Stachowska ◽  
Andrew Murphy ◽  
Claire Mellor ◽  
...  
Keyword(s):  
Optical Properties ◽  
Citric Acid ◽  
Binary Systems ◽  
Cyanuric Acid ◽  
Molar Ratio ◽  
Standard Size ◽  
Diverse Range ◽  
Aqueous Dispersions ◽  
Fluorescent Materials ◽  
Photoluminescent Materials

Abstract In this study we demonstrate simple guidelines to generate a diverse range of fluorescent materials in both liquid and solid state by focusing on the most popular C-dots precursors, i.e. the binary systems of citric acid and urea. The pyrolytic treatment of those precursors combined with standard size separation techniques (dialysis and filtration), leads to four distinct families of photoluminescent materials in which the emissive signal predominantly arises from C-dots with embedded fluorophores, cyanuric acid-rich C-dots, a blend of molecular fluorophores and a mixture of C-dots with unbound molecular fluorophores, respectively. Within each one of those families the chemical composition and the optical properties of their members can be fine-tuned by adjusting the molar ratio of the reactants. Apart from generating a variety of aqueous dispersions, our approach leads to highly fluorescent powders derived from precursors comprising excessive amounts of urea that is consumed for the build-up of the carbogenic cores, the molecular fluorophores and the solid diluent matrix that suppresses self-quenching effects.

scholarly journals A rich gallery of carbon dots based photoluminescent suspensions and powders derived by citric acid/urea

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Joanna D. Stachowska ◽  
Andrew Murphy ◽  
Claire Mellor ◽  
Diogo Fernandes ◽  
Ella N. Gibbons ◽  
...  
Keyword(s):  
Optical Properties ◽  
Citric Acid ◽  
Binary Systems ◽  
Cyanuric Acid ◽  
Molar Ratio ◽  
Standard Size ◽  
Diverse Range ◽  
Aqueous Dispersions ◽  
Fluorescent Materials ◽  
Photoluminescent Materials

AbstractIn this study we demonstrate simple guidelines to generate a diverse range of fluorescent materials in both liquid and solid state by focusing on the most popular C-dots precursors, i.e. the binary systems of citric acid and urea. The pyrolytic treatment of those precursors combined with standard size separation techniques (dialysis and filtration), leads to four distinct families of photoluminescent materials in which the emissive signal predominantly arises from C-dots with embedded fluorophores, cyanuric acid-rich C-dots, a blend of molecular fluorophores and a mixture of C-dots with unbound molecular fluorophores, respectively. Within each one of those families the chemical composition and the optical properties of their members can be fine-tuned by adjusting the molar ratio of the reactants. Apart from generating a variety of aqueous dispersions, our approach leads to highly fluorescent powders derived from precursors comprising excessive amounts of urea that is consumed for the build-up of the carbogenic cores, the molecular fluorophores and the solid diluent matrix that suppresses self-quenching effects.

Modified Technique for Measuring Platelet Aggregation

1997 ◽  
Vol 3 (3) ◽  
pp. 196-202 ◽  
Author(s):  
Alexander Kaplan ◽  
Svetlana Kaplan ◽  
Karen F. Marcoe ◽  
Lester R. Sauvage ◽  
William P. Hammond
Keyword(s):  
Platelet Aggregation ◽  
Citric Acid ◽  
Platelet Rich Plasma ◽  
Antiplatelet Agents ◽  
Current Approach ◽  
Molar Ratio ◽  
Maximum Height ◽  
Modified Technique ◽  
Aggregation Pattern

The turbidimetric method of Bom is the current approach for assessing the aggregation behavior of platelets. It has been of modest practical value, due to difficulty in standardizing laboratory techniques for plasma preparation and inadequate quantification of the aggregation process. We report a new technique of sedimented platelet rich plasma (SPRP) preparation that reduces the irregularities caused by factors associated with procuring and preparing blood samples and permits a more flexible protocol for laboratory practice. We quantified results with a platelet aggregation score, which is calculated by multiplying the ratio of the height of the initial wave of aggregation to the maximum height of the aggregation pattern by the total area under the aggregation curve and by the ratio of the whole blood platelet count and the number of platelets in the sample. Comparative analysis of platelet aggregation scores (n = 95) obtained with both plasma preparation techniques using a paired t test demonstrated no statistical differences ( t = 1.368, p = 0.174). To demonstrate the application of this modified method to evaluation of antiplatelet agents, the effects of aspirin and aspirin combined with citric acid on platelet aggregation were studied in vitro. The antiaggregatory effect of aspirin combined with citric acid was dependent on the pH and on their molar ratio, and was greater than the effect of aspirin alone. The SPRP protocol with platelet aggregation scoring methodology could be a valid alternative for measurement of the platelets' propensity to aggregate and the effect of antithrombotic treatments. Key Words: Platelet aggregation— Aspirin—Citric acid.

One-pot synthesis of double silane-functionalized carbon dots with tunable emission and excellent coating properties for WLEDs application

2021 ◽  
Author(s):  
Wenbing Cao ◽  
Yuhan Wu ◽  
Xin Li ◽  
Xuanfeng Jiang ◽  
Yuhong Zhang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Carbon Dots ◽  
Great Influence ◽  
Alkoxy Group ◽  
Color Temperature ◽  
Molar Ratio ◽  
Coating Properties ◽  
One Pot ◽  
Light Emitting ◽  
Light Emitting Devices

Abstract Silane-functionalized carbon dots (SiCDs) can be exploited as effective color converting materials for the solid-state light-emitting devices. However, most of SiCDs reported thus far have shown photoluminescence emissions in the blue and green spectral range, which limit them to construct an efficient white light-emitting diodes (WLEDs) due to the lack of long-wavelength emission. Herein, a series of double silane-functionalized carbon dots (DSiCDs) were prepared via a one-step solvothermal method. The results show that the organic functional group of the silane has great influence on the optical properties of DSiCDs and the number of alkoxy group in the silane has great influence on coating properties of DSiCDs. In addition, the DSiCDs prepared by (3-aminopropyl)triethoxysilane and N-[3-(Trimethoxysilyl)propyl]ethylenediamine with molar ratio of 7:3 show excellent optical properties with the maximum emission at 608 nm under 400 nm excitation. Furthermore, they can be completely dried within 1 h at room temperature to form fluorescent coating with high stability and strong adhesion to the substrate. Together with their excellent optical and coating properties, they can be directly coated on LED chips to prepare WLEDs, with a CIE coordinate of (0.33,0.31), color rendering index of 81.6, and color temperature of 5774 K.

Study on Synthesis of Ester of Citric Acid and Palmityl Alcohol

2014 ◽  
Vol 900 ◽  
pp. 361-364
Author(s):  
Xiao Hui Wang ◽  
Xi Hua Du ◽  
Li Min Dong
Keyword(s):  
Reaction Time ◽  
Citric Acid ◽  
Cation Exchange ◽  
Sulfonic Acid ◽  
Exchange Resin ◽  
Cation Exchange Resin ◽  
Molar Ratio ◽  
Esterification Reaction ◽  
Process Conditions ◽  
Toluene Sulfonic Acid

Esters of Citric acid and palmityl alcohol were synthesized by esterification reaction under catalysis of cation exchange resin and P-toluene sulfonic acid respectively. The effects of amount of catalyst, ratio of raw materials, reaction time and temperature on the synthesis reaction were investigated . The experimental results showed that optimum of process conditions were 1:1~1:1.5 molar ratio of citric acid and palmityl alcohol, reaction temperature of 130~140°C, reaction time of 2 h. Conversion of palmityl alcohol were all more than 90% under 0.3% dosage using p-toluene sulfonic acid as the catalyst, or 0.5% dosage using 721 cation exchange resin with sulfonic acid type as catalyst. The synthesized product had good surface activity.

scholarly journals Microbubbles Decorated with Dendronized Magnetic Nanoparticles for Biomedical Imaging. Effective Stabilization via Fluorous Interactions

2019 ◽  
Author(s):  
Da Shi ◽  
Justine Wallyn ◽  
Dinh-Vu Nguyen ◽  
Francis Perton ◽  
Delphine Felder-Flesch ◽  
...  
Keyword(s):  
Molar Ratio ◽  
Aqueous Dispersions ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Investigation ◽  
End Groups ◽  
Mixed Films ◽  
Effective Stabilization ◽  
Effective Result ◽  
End Group

Dendrons fitted with three oligoethylene glycol (OEG) chains, one of which carrying a fluorinated or hydrogenated end group, and bearing a bisphosphonate polar head (C n X2 n +1OEG8Den, X = F or H; n= 2 or 4) were synthesized and grafted on the surface of iron oxide nanoparticles (IONPs) for microbubble-mediated imaging and therapeutic purposes. The size and stability of the dendronized IONPs (IONP@C n X2 n +1OEG8Den) in aqueous dispersions were monitored by dynamic light scattering. Investigation of the spontaneous adsorption of IONP@C n X2 n +1OEG8Den at the interface between air - or air saturated with perfluorohexane - and an aqueous phase establishes that exposure to the fluorocarbon gas markedly increases the rate of adsorption of the dendronized IONPs to the gas/water interface and decreases the equilibrium interfacial tension. This suggests that fluorous interactions are at play between the supernatant fluorocarbon gas and the fluorinated end groups of the dendrons. Furthermore, small, stable perfluorohexane-stabilized microbubbles (MBs) with a dipalmitoylphosphatidylcholine (DPPC) shell that incorporates IONP@C n X2 n +1OEG8Den (DPPC/Fe molar ratio 28:1) were prepared and characterized using both optical microscopy and an acoustical method of size determination. The dendrons fitted with fluorinated end groups lead to smaller and more stable MBs than those fitted with hydrogenated groups. The most effective result is already obtained with C2F5, for which MBs, ~1.0mm in radius, reach a half-life of ~6.0 h. An atomic force microscopy investigation of spin-coated mixed films of DPPC/IONP@C2X5OEG8Den combinations (molar ratio 28:1) shows that the IONPs grafted with the fluorinated dendrons are located within the phospholipid film, while those grafted with the hydrocarbon dendrons are completely absent from the phospholipid film.

scholarly journals Colorless and Transparent Copolyimides and Their Nanocomposites: Thermo-Optical Properties, Morphologies, and Gas Permeabilities

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 585 ◽  
Author(s):  
Hyeon Shin ◽  
Young-Je Kwark ◽  
Jin-Hae Chang
Keyword(s):  
Optical Properties ◽  
Coefficient Of Thermal Expansion ◽  
Amic Acid ◽  
Gas Permeation ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Thermal Imidization ◽  
Organically Modified ◽  
Permeation Properties

A series of linear aromatic copolyimides (Co-PIs) were synthesized by reacting 4,4′-biphthalic anhydride (BPA) with various molar contents of 2,2′-bis(trifluoromethyl)benzidine (TFB) and p-xylylenediamine (p-XDA) in N,N′-dimethylacetamide (DMAc). Co-PI films were fabricated by solution casting and thermal imidization with poly(amic acid) (PAA) on glass plates. The thermo-optical properties and gas permeabilities of Co-PI films composed of various molar ratios of p-XDA (0.2–1.0 relative to BPA) were investigated. Thermal properties were observed to deteriorate with increasing p-XDA concentration. However, oxygen-transmission rates (O2TRs) and optical transparencies improved with increasing p-XDA concentration. Co-PI hybrids with a 1:0.2:0.8 molar ratio of BPA:TFB:p-XDA and organically modified hectorite (STN) were prepared by the in situ intercalation method. The morphologies and the thermo-optical and gas permeation properties of the hybrids were examined as functions of STN loading (5–50 wt %). XRD and TEM revealed substantial increases in clay particle agglomeration in the Co-PI hybrid films as the clay loading was increased from 5 to 50 wt %. The coefficient of thermal expansion (CTE) and the O2TR of a Co-PI hybrid film were observed to improve with increasing STN concentration; however, its optical transparency decreased gradually with increasing STN concentration.

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