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In this study, we have proposed an electrochemiluminescence (ECL) signal amplification system which is based on two-dimensional (2D) flower-like CdS@Co/Mo-MOF composites as a co-reaction accelerator of the g-C3N4/S2O82− system for ultrasensitive detection of chlorpromazine hydrochloride (CPH). Specifically, the 2D flower-like Co/Mo-MOF with mesoporous alleviated the aggregation of CdS NPs while simultaneously fostering reactant-active site contact and improving the reactant–product transport rate. This allowed the material to act as a novel co-reaction accelerator, speeding up the transformation of the S2O82− into SO4•− and enhancing the cathodic ECL emission of g-C3N4. Moreover, the signal probe which was synthesized by coupling the 2D CdS@Co/Mo-MOF and graphitic carbon nitride (g-C3N4) achieved the generation of SO4•− in situ and reduced energy loss. The results confirmed that the ECL signal was enhanced 6.2-fold and stabilized by CdS@Co/Mo-MOF. Based on the extremely strong quenching effect of chlorpromazine hydrochloride (CPH) on this system, a "signal-off" type sensor was constructed. The sensor demonstrated excellent sensitivity and linear response to CPH concentrations ranging from 1 pmol L−1 to 100 μmol L−1, with a low detection limit of 0.4 pmol L−1 (S/N = 3). [ABSTRACT FROM AUTHOR]

Exploring fluorescence sensing materials for dichromate (Cr2O72−) has garnered considerable attention due to its high toxicity to organisms. In this work, a cationic SiF62--containing metal-organic framework (SIFSIX MOF) with the formula [Cd(TPI)2(H2O)2]·SiF6·4H2O (1) was synthesized by the reaction of 2,4,5-tri(4-pyridyl)imidazole (TPI) and CdSiF6 at room temperature. Crystal structural analysis revealed that the coordination between TPI and Cd2+ in 1 formed one-dimensional (1D) TPI-Cd coordination chains, while the lattice SiF62− not only acted as the counterion to maintain the charge balance but also contributed to formation of the three-dimensional (3D) supramolecular structure through hydrogen bonds. Fluorescence sensing experiments suggested that 1 could work as an efficient selective sensor towards Cr2O72− via a fluorescence quenching effect with fast response, high sensitivity and superior anti-interfering capacity. Mechanistic studies confirmed that the fluorescence quenching may be attributed to the resonance energy transfer and structural transformation caused by anion exchange. [ABSTRACT FROM AUTHOR]

Schiff bases with pyrene, anthracene or naphthalene groups can act as simple, sensitive, and selective sensors for the detection of trace explosives. We have prepared three new types of Schiff bases with fluorescent properties as fluorescent probes for use in the fluorescence detection of explosives. The detection properties of the synthesized compounds of photophysical and fluorescent explosives were investigated. Spectroscopic methods were used for the structural characterization of the compounds. Within the scope of the study, compounds (A, B and C) were used as fluorescent probes in the detection of some explosives and the data obtained were recorded. Instead of the quenching effect expected by the explosives on the emissions of the compounds, it was observed in some experiments that the emission intensity due to aggregation increased. In addition, the color measurements (CIE standards) and Color temperature (CCT) of the compounds were calculated. [ABSTRACT FROM AUTHOR]

The quenching effect is a phenomenon in which the scintillation efficiency decreases when energetic particles with high linear energy transfer, such as high-energy ions, deposit energy within the scintillator. From the viewpoint of discriminating between neutrons and gamma rays in the neutron scintillator, evaluating the quenching effect is crucial because the high-energy ions produced by neutron reactions are used to detect neutrons. Using the user-defined subroutine in the Monte Carlo simulation code PHITS, we demonstrated the calculation of the pulse height spectra obtained from Li-containing scintillators, in which the quenching effect is considered based on the Birks' formula. By comparing the experimental pulse height spectra with simulation results, which consider the experimental broadening, for the neutron peak and Compton edge formed by mono-energetic gamma rays, we determined the quenching coefficient in the Birks' formula for Li glass, Ce:LiCaAlF6 and Eu:LiCaAlF6 scintillators. [ABSTRACT FROM AUTHOR]

In this study, we have proposed an electrochemiluminescence (ECL) signal amplification system which is based on two-dimensional (2D) flower-like CdS@Co/Mo-MOF composites as a co-reaction accelerator of the g-C3N4/S2O82− system for ultrasensitive detection of chlorpromazine hydrochloride (CPH). Specifically, the 2D flower-like Co/Mo-MOF with mesoporous alleviated the aggregation of CdS NPs while simultaneously fostering reactant-active site contact and improving the reactant–product transport rate. This allowed the material to act as a novel co-reaction accelerator, speeding up the transformation of the S2O82− into SO4•− and enhancing the cathodic ECL emission of g-C3N4. Moreover, the signal probe which was synthesized by coupling the 2D CdS@Co/Mo-MOF and graphitic carbon nitride (g-C3N4) achieved the generation of SO4•− in situ and reduced energy loss. The results confirmed that the ECL signal was enhanced 6.2-fold and stabilized by CdS@Co/Mo-MOF. Based on the extremely strong quenching effect of chlorpromazine hydrochloride (CPH) on this system, a “signal-off” type sensor was constructed. The sensor demonstrated excellent sensitivity and linear response to CPH concentrations ranging from 1 pmol L−1 to 100 μmol L−1, with a low detection limit of 0.4 pmol L−1 (S/N = 3).

The effect of carboxyl and hydroxyl groups attached to the benzene ring on the photodegradation of anthracene (Ant) and pyrene (Pyr) in ice was investigated. The present study aims to explore the inhibition mechanism of five dissolved organic matter (DOM) model compounds’ materials such as benzoic acid, o-hydroxybenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, and 3-phenyl propionic acid on the degradation of Ant and Pyr in ice. The photodegradation rate of Ant and Pyr were 50.33 and 37.44% in ice, with the photodegradation rate of Ant being greater than that of Pyr. The five DOM model compounds inhibited the photolysis of Ant and Pyr, and the influence mechanism on the photodegradation of Ant and Pyr depended upon the types and positions of functional groups on the benzene. Among them, the structure in which the carboxyl group was directly connected to the benzene ring and carboxyl was located at the ortho position of a hydroxy group had a strong inhibitory effect on the photodegradation of Ant and Pyr. Light-screening effects and quenching effects were the main inhibiting mechanism, and the binding ability of DOM model compounds material and PAHs is dominantly correlated with its inhibiting effect. HIGHLIGHTS Among five DOM model compounds, the structure of the carboxyl group directly connected with the benzene ring had stronger inhibition of photodegradation of Ant and Pyr.; The inhibition of Ant and Pyr by the DOM fragment models were identified mainly due to light-screening effect and the quenching effect of DOM.;

A spectrofluorimetric approach that is sensitive, simple, validated, and cost‐effective has been proposed for the estimation of amlodipine (AML) and perindopril (PER) in their bulk powders, pharmaceutical formulations, and spiked human plasma. The recommended approach utilized the quantitative quenching effect of the two cited drugs on the fluorescence intensity of erythrosine B, as a result of complex binary reactions among each drug with erythrosine B at pH 3.5 (Teorell and Stenhagen buffer). The quenching of erythrosine B fluorescence was recorded at 554 nm after excitation at 527 nm. The calibration curve was detected in the range 0.25–3.0 μg ml−1, with a correlation coefficient of 0.9996 for AML, and 0.1–1.5 μg ml−1, with a correlation coefficient of 0.9996 for PER. The established spectrofluorimetric approach was validated for the estimation of the cited drugs with high sensitivity regarding International Council on Harmonization guidelines. Therefore, the established approach could be utilized for quality control of the cited drugs in their pharmaceutical formulations. [ABSTRACT FROM AUTHOR]

Special attention is given to the development of rapid and sensitive detection of nitroaromatic explosives for homeland security and environmental concerns. As part of our contribution to the detection of nitroaromatic explosives, fluorescent materials (A), (B) and (C) were synthesized from the reaction of 1,2-diaminocyclohexane with pyrene-1-carbaldehyde, anthracene-9-carbaldehyde and 2-hydroxy-1-naphthaldehyde, respectively. The structures of the prepared fluorescent azomethine probes were confirmed using FTIR, 1H-NMR and 13C-NMR spectroscopies. The basis of the study is the use of the synthesized materials as fluorescent probes in the photophysical and fluorescence detection of some nitroaromatic explosives. Emission increases occurred due to aggregation caused by π-π stacking in synthesized azomethines. To measure the nitroaromatic detection capabilities of fluorescence probes, fluorescence titration experiments were performed using the photoluminescence spectroscopy. It was observed that compound A containing pyrene ring provided the best emission intensity-increasing effect due to aggregation with the lowest LOD value (14.96 μM) for the sensing of 4-nitrophenol. In compounds B and C, nitrobenzene with the lowest LOD (16.15 μM and 23.49 μM respectively) caused the most regular emission increase, followed by picric acid. [ABSTRACT FROM AUTHOR]

Herein, dual-emission carbon dots (DE-CDs) were synthesized using a one-pot hydrothermal method. DE-CDs exhibited two well-separated peaks at 433 and 513 nm under ultraviolet excitation. The prepared DE-CDs offer selective detection of Fe3+ ions via inner filter effect (IFE) and Pb2+ ions via aggregation-induced enhancement (AIE). The obtained DE-CDs showed a good affinity for both Fe3+ and Pb2+ ions in the presence of various interfering ions. The limits of detection were 0.797 ppm and 4.739 ppm for Pb2+ and Fe3+, respectively. The finding reveals the huge potential of DE-CDs for the selective detection of multiple targets in one solution. [ABSTRACT FROM AUTHOR]

For quantitation of amlodipine (AML) and perindopril (PER) in their authentic, pharmaceutical formulations and spiked human plasma, a simple, sensitive, validated and inexpensive spectrofluorimetric method has been developed. The proposed method is developed to be based on quantitative quenching effect of two antihypertensive drugs on Eosin Y's native fluorescence which was achieved by developing binary complexes between each of the cited drugs in an acidic environment using acetate buffer (pH 4.4) with Eosin Y. Fluorescence quenching was recorded at 544 nm after excitation at 425 nm. For AML and PER, calibration curves were obtained over the range of 0.3–3.0 µg/mL and 0.2–2.0 µg/mL, respectively, with correlation coefficients of 0.9993 and 0.9995, respectively. The developed method was validated according to ICH guidelines. The proposed spectrofluorimetric method is regarded new and sensitive. As a result, the proposed method might be used to estimate the quality of the cited drugs in their pharmaceutical formulations and biological fluid. [ABSTRACT FROM AUTHOR]

Rapid and selective detection of nitroaromatic explosives is very important for public safety, life, and environmental health. Current instrumental techniques suffer from high cost and poor site used. In order to investigate fluorescence sensing of nitroaromatics, we prepare a new small fluorescence probe derived from pamoic acid. This study covers the synthesis of Pamoic acid based [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) material and characterization of its structure. The methylation of Pamoic acid ester, which we have successfully synthesized in our previous studies, was carried out in this study. Determination of the photophysical and fluorescent nitroaromatic detection properties of the compound forms the basis of the study. Structural characterization of the synthesized compound [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) was characterized using spectroscopic methods. In addition, Molecular structure of the synthesized compound was determined by single crystal X-ray diffraction studies. In the final step, compounds [diisopropyl 4,4'-methylenebis(3-hydroxy-2-naphthoate)] (1) and [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) were tested as fluorescent probes for the detection of some nitroaromatic explosives. It is seen that Nitrobenzene provides the best quenching effect on the compound [diisopropyl 4,4'-methylenebis(3-hydroxy-2-naphthoate)] (1) containing the -OH group, with lowest the limit of detection (LOD) value. It was observed that Picric acid provided the best quenching effect with lowest the limit of detection (LOD) value in the compound [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) obtained by methylation of the -OH group in the compound [diisopropyl 4,4'-methylenebis(3-hydroxy-2-naphthoate)] (1). [ABSTRACT FROM AUTHOR]

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Abstract We investigate the fluorescence from submonolayer rhodamine 6G molecules near gold nanoparticles (NPs) at a well-controlled poly (methyl methacrylate) (PMMA) interval thickness from 1.5 to 21 nm. The plasmonic resonance peaks of gold NPs are tuned from 530 to 580 nm by the PMMA spacer of different thicknesses. Then, due to the plasmonic resonant excitation enhancement, the emission intensity of rhodamine 6G molecules at 562 nm is found to be enhanced and shows a decline as the PMMA spacer thickness increases. The variation of spectral intensity simulated by finite-difference time-domain method is consistent with the experimental results. Moreover, the lifetime results show the combined effects to rhodamine 6G fluorescence, which include the quenching effect, the barrier effect of PMMA as spacer layer and the attenuation effect of PMMA films.

• The yield of scintillation photons in high LET domain is suppressed. • This study proposed an alternative method for estimating the suppression of yields. • The new model uses sequential FRET calculations with Geant4. • The proposed computational model improved the prediction of suppressed yields. The yield of scintillation photons emitted from scintillators is considered to be proportional to the LET (linear energy transfer) which is energy distribution per unit length, in the low-LET domain, but not proportional in the high LET domain due to the suppression yield from the so-called quenching effect. Ogawa et al. proposed a computational method to estimate scintillation yield using Monte Carlo simulations considering the principle of the FRET (fluorescence resonance energy transfer) process, which is a phenomenon of energy transfer between fluorescent molecules. In their study, the track structure simulations could reproduce measured yields of scintillation. However, Ogawa et al.'s model was not suitable for estimating the scintillation yields when the particle energy was low when using condensed history simulations. Therefore, we propose a new method for estimating scintillation yields more accurately using Geant4 to improve the model calculations based on condensed history simulations. We simulated the local energy deposition pattern in a NE102A plastic scintillator to calculate the number of excitors in the microscopic volume for various nuclides (helium to argon ions). The suppressed scintillation yields were estimated using the model calculations of sequential FRET processes while considering the inactivation of the excitors selected as donors of the FRET process. The model calculations successfully reproduced the experimental scintillation yields within 10 % error for the lighter ions up to neon. However, when the analysis was repeated for silicon and argon, the maximum error in the scintillation yields increased up to 27 %. The proposed computational model for the evaluation of the suppressed scintillation yields emitted from NE102A scintillator irradiated with heavy ions using sequential FRET calculations with condensed history method returned simulated scintillation yields. [ABSTRACT FROM AUTHOR]

We investigate the fluorescence from submonolayer rhodamine 6G molecules near gold nanoparticles (NPs) at a well-controlled poly (methyl methacrylate) (PMMA) interval thickness from 1.5 to 21 nm. The plasmonic resonance peaks of gold NPs are tuned from 530 to 580 nm by the PMMA spacer of different thicknesses. Then, due to the plasmonic resonant excitation enhancement, the emission intensity of rhodamine 6G molecules at 562 nm is found to be enhanced and shows a decline as the PMMA spacer thickness increases. The variation of spectral intensity simulated by finite-difference time-domain method is consistent with the experimental results. Moreover, the lifetime results show the combined effects to rhodamine 6G fluorescence, which include the quenching effect, the barrier effect of PMMA as spacer layer and the attenuation effect of PMMA films. [ABSTRACT FROM AUTHOR]

A novel hyperbranched mono-component intumescent flame retardant poly(piperazine methylphosphonic acid pentaerythritol ester) defined as PPMPPE was synthesized, and its chemical structure was characterized. The individual PPMPPE was incorporated into polyethylene (PE), and the fire resistance, thermal properties and flame retardant mechanism of PE composites were investigated in detail. The 1.6-mm PE/PPMPPE sheets fulfilled UL-94 V-0 level during vertical burning tests, and the limiting oxygen index was 25.3% when the loading amount of PPMPPE was 22 wt%. PPMPPE was completely melted, and the expanded char layer was generated on heating. The addition of PPMPPE stimulated the degradation and charring of PE composites in advance and improved the residual mass and thermal stability of FR-PE at high temperature. The cone calorimeter tests verified that the heat release rate and total heat release of PE/PPMPPE composites were obviously declined. PPMPPE exerted shielding effect in condensed phased and quenching active free radicals in the gas phase. The flame was constrained and even extinguished. Thus, PE composites fulfilled superior flame retardant properties. [ABSTRACT FROM AUTHOR]

Electrochemiluminescence (ECL) as an analytical technology with a perfect combination of electrochemistry and spectroscopy has received considerable attention in bioanalysis due to its high sensitivity and broad dynamic range. Given the selectivity of bio-recognition elements and the high sensitivity of the ECL analysis technique, ECL biosensors are powerful platforms for the sensitive detection of biomarkers, achieving the accurate prognosis and diagnosis of diseases. MicroRNAs (miRNAs) are crucial biomarkers involved in a variety of physiological and pathological processes, whose aberrant expression is often related to serious diseases, especially cancers. ECL biosensors can fulfill the highly sensitive and selective requirements for accurate miRNA detection, prompting this review. The ECL mechanisms are initially introduced and subsequently categorize the ECL biosensors for miRNA detection in terms of the quenching agents. Furthermore, the work highlights the signal amplification strategies for enhancing ECL signal to improve the sensitivity of miRNA detection and finally concludes by looking at the challenges and opportunities in ECL biosensors for miRNA detection., (© 2023 Wiley‐VCH GmbH.)

Graphdiyne (GDY) as an emerging carbon nanomaterial has attracted increasing attention because of its uniformly distributed pores, highly π-conjugated, and tunable electronic properties. These excellent characteristics have been widely explored in the fields of energy storage and catalysts, yet there is no report on the development of sensors based on the outstanding optical property of GDY. In this paper, a new sensing mechanism is reported built upon the synergistic effect between inner filter effect and photoinduced electron transfer. We constructed a novel nanosensor based upon the newly-synthesized nanomaterial and demonstrated a sensitive and selective detection for both Fe3+ ion and ascorbic acid, enabling the measurements in real clinical samples. For the first time fluorescent graphdiyne oxide quantum dots (GDYO-QDs) were prepared using a facile ultrasonic protocol and they were characterized with a range of techniques, showing a strong blue-green emission with 14.6% quantum yield. The emission is quenched efficiently by Fe3+ and recovered by ascorbic acid (AA). We have fabricated an off/on fluorescent nanosensors based on this unique property. The nanosensors are able to detect Fe3+ as low as 95 nmol L−1 with a promising dynamic range from 0.25 to 200 μmol L−1. The LOD of AA was 2.5 μmol L−1, with range of 10–500 μmol L−1. It showed a promising capability to detect Fe3+ and AA in serum samples. [ABSTRACT FROM AUTHOR]

The DArk Matter Particle Explorer (DAMPE) is a satellite-borne, calorimetric-type, high-energy-resolution detector for the precise measurement of high-energy electrons, gamma rays, and nuclei from deep space. The DAMPE electromagnetic calorimeter consists of bismuth germanate (BGO) crystals that can measure incident hadron energies from 50 GeV to 100 TeV. For an inorganic scintillator, such as BGO, the nonlinear fluorescence response when measuring ions contributes to the difference between the experimental data and Monte Carlo simulations. This article reports the BGO quenching nonlinearity occurring in the DAMPE experiment. The ionization energy response of BGO to several kinds of ions lighter than iron is investigated by conducting beam tests and analyzing flight data. We compare the scintillator output with the energy loss according to GEANT4 simulations and determine the quenching parameters. The combined result of beam test and flight experiment shows that the quenching effect strongly depends on the density of the ionization energy loss. [ABSTRACT FROM AUTHOR]

In solar thermal utilization, effective photo capture and photothermal conversion are crucial. Improving the nonradiative transition rate of photoexcited electrons is important to enhance the photothermal conversion efficiency and develop efficient solar thermal utilization. Herein, we designed a new kind of light absorption‐enhanced and efficient photothermal conversion material, namely, Fe2O3‐functionalized reduced graphene oxide (Fe2O3–RGO). On the basis of the selective absorption (350–560 nm) of Fe2O3 and the synergistic effect of RGO on the quenching energy transfer of the excited state of Fe2O3 and ultrafast nonradiative thermal decay of RGO, the optical absorption capacity, and photothermal conversion efficiency of the composites were effectively improved. Fe2O3–RGO can be successfully applied to photothermal conversion phase change materials and seawater solar desalination, showing excellent photothermal conversion ability and application prospect. [ABSTRACT FROM AUTHOR]

The electrochemiluminescence (ECL) system based on the ruthenium complex has become a powerful tool in the field of analytical chemistry. However, the non‐aqueous ECL luminescence system, which does not involve complex nano‐modification, has not been widely used for the determination of analytes. In this study, N ‐methyl pyrrolidone was selected as the solvent, and it could also act as a co‐reactant of Rubpy32+. Based on this, a simple ECL system without nanomaterials was established. Strong ECL was generated. Furthermore, a quenching effect between the excited state of Rubpy32+ and sulphamethoxazole (SMZ) was observed. Based on this, a sensitive ECL sensor for detecting SMZ is constructed. A linear relationship between ECL signal quenching intensity (ΔI) and the logarithm of SMZ concentration (log C) in the concentration range of 1 × 10−7 –1 × 10−5 mol/l is obtained. The limit of detection is as low as 3.33 × 10−9 mol/l. The method has been applied to the detection of SMZ in tap water samples with different concentration levels with satisfactory results, and the recovery was 95.3–102.6%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two phosphorus-nitrogen phenolic resins (DPO-PR and DOPO-PR) were synthesized. • The DPO-PR and DOPO-PR were applied in epoxy resins to improve the flame retardancy. • The flame retardant mechanisms of DPO-PR/EP and DOPO-PR/EP were analyzed. In this paper, two phosphorus-nitrogen phenolic resins (DPO-PR, DOPO-PR) were synthesized from phenol, paraformaldehyde, dicyandiamide, DOPO, and diphenylphosphine oxide (DPO) as raw materials as curing agents and were applied in epoxy resins. The structures of DPO-PR and DOPO-PR were characterized by FTIR, 1H NMR and 31P NMR. In the TGA test, the decomposition temperature of DPO-PR/EP and DOPO-PR/EP decreased, but the residue yield increased substantially. DPO-PR/EP had a higher LOI value than DOPO-PR/EP at the same addition amount. Compared with PR/EP, DPO-PR/EP showed that pk-HRR decreased by 41.5 %, THR decreased by 29.4 %, and a slight increase in residue yield. DPO-PR/EP and DOPO-PR/EP were analyzed by TG-MS, and the results showed that both DPO-PR/EP and DOPO-PR/EP can decompose phosphorus free radicals to exert quenching effects. Characterization of the char layer by SEM and XPS showed that DPO-PR and DOPO-PR were able to produce phosphoric acid substances to promote the dehydration of the epoxy resin into char layer, enhance the integrity of the char layer of the epoxy resin, and effectively exert the shielding and barrier effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon dots (CDs) were synthesized from glucose and acid citric via the hydrothermal method. • The Raman signal of hydrogen bonding network was recorded on the photoluminescence (PL) spectra of the prepared CDs. • The hydrogen bonding network reduced the PL intensity of CDs in weak alkaline conditions. • A new hypothesis based on the interaction between the hydrogen bonding network and CD particles was proposed to explain the pH-sensing mechanism of the CDs. Recently, carbon dots (CDs) have received huge attention from scientists around the globe due to their unique properties, including excellent optical properties, good photobleaching, good biocompatibility, and ease of production. Notably, CDs exhibit novel results in pH sensing applications in water and intracellular environments due to their excellent anti-interfering ability and photostability. Herein, we successfully synthesized CDs by hydrothermal method using glucose and citric acid as precursors. The formation and breaking of hydrogen bonding play an important role in pH-sensing mechanisms of CDs. By using Raman signal of the hydrogen bonding in the photoluminescence (PL) spectra of CDs, we investigate here the effect of hydrogen bonding on the pH-sensing of CDs. It is expected that the mechanism of pH-sensing on the PL signal could be unraveled. As the results, the hydrogen bonding significantly reduced the PL intensity of CDs in a pH range of 7–11 but it did not influence the PL of CDs in higher pH conditions. Based on the interaction between hydrogen bonding and CDs, a new model for the pH-sensing mechanism of CDs was proposed. This work sheds new light on the mechanism of pH-sensing on the PL signal and suggests a new application of CDs in moisture and water sensors for air, soil, food, and commercial chemicals. [ABSTRACT FROM AUTHOR]

Fluorescence analysis is a simple and a highly sensitive method for detection of small amounts of biologically active substances. In this study, a complexation of terbium(III) chelates with 1,10-phenanthroline and ascorbic acid (AA) and luminescent properties of complexes were investigated. The influence of pH and solubilization of complexes by micellar solutions of nonionic, cationic, and anionic surfactants on fluorescence was studied. The quenching effect of terbium ion fluorescence was detected upon an introduction of ascorbic acid. The quenching effect of the complex with mixed ligands Tb(1,10-phenanthroline)-AA allows for the detection of ascorbic acid with the limit of 7.4 × 10−5 mol·L−1.

• Determination of cochineal in strawberry jam by EEM and four-way PARAFAC model. • Carmoisine acted as a quencher in the fluorescence signal of cochineal. • Four-way PARAFAC avoids false compliant decisions in the determination of cochineal. • Cochineal was unequivocally identified and quantified in the presence of carmoisine. • Cochineal was detected in the strawberry jam above its maximum residue level. The determination of cochineal (E-120) in strawberry jam was carried out in the presence of carmoisine (E-122) using the four-way PARAFAC decomposition and excitation-emission fluorescence matrices. In the measured conditions, there was no fluorescence signal for carmoisine due to a strong quenching effect and this colorant also led to a decrease of the fluorescence signal of cochineal. The European Union has fixed a maximum residue level, MRL, for cochineal in jam (100 mg kg−1). Therefore, the addition of other food colorant (carmoisine) in the jam could lead to false compliant decisions. The four-way PARAFAC decomposition avoided false compliant decisions caused by the quenching effect. Cochineal was unequivocally identified. Detection capability (CCβ) was 0.72 mg L−1 for probabilities of false positive and false negative fixed at 0.05. Cochineal was detected in the jam (104.63 mg kg−1) above the MRL. This amount was compared with the one obtained using a HPLC/DAD method. [ABSTRACT FROM AUTHOR]

The uniform heated rod bundle Critical Heating Flux (CHF) tests have been often conducted as a part of mixing vane performance evaluation processes. Presently, several commercial CHF correlations were developed based on a large amount of rod bundle CHF data using axial uniformly heated rod bundles. With a uniformly heated test section, majority of CHF events are dominated by dry-out mechanism under high quality, high void fraction local conditions. Considering the inverse proportional relationship between the quality and CHF, for an axially uniformly heated test section, the CHF events should occur near the end of heating length (EOHL) where the void fraction/quality is the highest. However, the upstream shift of CHF location is often observed in the uniform heating tests, sometime as much as 250 mm or higher upstream from the EOHL. In the past, without any sufficient convincing proof, long dryout areas as well as "unknown" "mysteries" mixing effects from the mixing vane grid were often considered as the contributing factors for this type of upstream shift. Based on further and detailed examination, this paper offer analysis and evidence to demonstrate another most plausible explanation, exit quenching effect, which ultimately concludes that rod bundle CHF using uniform heated rods could have data with huge measurement uncertainty and as much as over 30% of non-conservatism due to heat lose and quenching effects at the exit of the heated length. The quenching effect at the exit of heater length is mainly due to reflood phenomena generated between the high void/low flow test section exit region and the relatively cold single phase coolant immediately above in the top plenum resulting from either excessive heat loss or operating transient condition. In this paper, system code and CFD modeling were utilized to simulate the quenching phenomena in both steady state and transient conditions. The significant void fraction drop near the exit of the test section due to quenching were clearly observed in these simulations and also evidenced by the various degrees of coloration of the heaters surface in the experiment. This exit reflood quenching phenomena may change the CHF location, suppress boiling, cool down the heated surface, and eventually lead to non-conservative high CHF values. Based on this analysis and experimental observation, it is concluded that the CHF correlations developed based on these type of data are potentially non-conservative in various degrees pending on local thermal-hydraulic conditions, which should be taken into consideration for their applications, especially for safety analysis in nuclear reactor. [ABSTRACT FROM AUTHOR]

The unsaturated polyester resins (UPR) were usually applied in electronic equipment, but the intrinsic flammability severely retrained their application. A mono‐component flame retardant poly (piperazine methylphosphonic acid neopentylglycol ester) (PPMPNG) made in our lab was selected and applied to improve their flame retardant performance. The UPR thermosets achieved UL‐94 V‐0 grade during vertical burning tests and the limiting oxygen index was as high as 32.1% when 15 wt% PPMPNG was incorporated. PPMPNG promoted the decomposition and carbonization of UPR materials in advance during heating process, and the residual mass was effectively enhanced at high temperature. The flame retardant mechanism of UPR/PPMPNG thermosets was investigated by pyrolysis‐gas chromatography/mass spectrometry tests, and the measurement of the morphologies and chemical components of the char residue. The phosphine oxygen radical was generated and then quenched the active free radicals in gas phase. Moreover, the av‐EHC of FR‐UPR was declined from 15.8 MJ kg−1 of pure UPR to 8 9 MJ kg−1 corresponding a reduction of 43.6%, which also verified the flame retardant effect in gas phase. The compact, integrated, and graphitized char layer was produced on materials surface and then exerted excellent barrier effect in condensed phase. Thus, the UPR/PPMPNG composites were conferred superior flame retardant properties. [ABSTRACT FROM AUTHOR]

Quenching effect of photoconductive semiconductor material has important applications in areas like detecting semiconductor defect and infrared light. In this paper, vapor–liquid–solid (VLS) method is improved to grow nanowires by using a heat resisting quartz tube as the vessel. With the conditions of gold catalysis, appropriate temperature, and ease of handling, gradient-bandgap CdSSe nanowires were grown successfully. We study the quenching effect of different component parts of the nanowire, respectively, and find that the quenching degree increases with the increasing optical intensities of different bandgap nanowires when the power injection is below 10 − 8 W. However, since more recombination centers would turn into the trap energy level centers leading to more electrons to jump into the conduction band with the increasing density of CdS, the peak of quenched rate for 90% CdS proportion nanowire arrives earlier than 90% CdSe proportion, and the peak of quenched rate for CdSe still does not appear even when the optical intensity reaches 10 − 6 W. Our experiment provides an effective and convenient method for the defect-level detection of semiconductor materials, and can also develop high resolution infrared detectors under the material limitation conditions. [ABSTRACT FROM AUTHOR]

Graphical abstract Schematic illustration of a novel "on-off" enzyme-free ECL aptasensor was developed for highly sensitive and rapid detection of Staphylococcus aureus. Highlights • A novel "on-off" enzyme-free ECL aptasensor was developed for highly sensitive and rapid detection of S. aureus. • A high ECL intensity was achieved by the dual enhancement of AuNPs and catalytic activity of hemin. • ECL system and its quenching mechanism was thoroughly explored. • The biosensing method was successfully applied for the detection of S. aureus from human urine. Abstract In this study, based on gold nanoparticles (AuNPs) and hemin as the regenerable enhancers of S 2 O 8 2−/O 2 electrochemiluminesce (ECL) system, a highly sensitive "on-off" ECL aptasensor was constructed for S. aureus detection by the quenching effect of MoS 2 -PtNPs. Firstly, the polished glass carbon electrode (GCE) was subsequently modified with reduced graphene oxide (RGO), AuNPs and thiol-terminated aptamer, and MoS 2 -PtNPs-Vancomycin (MoS 2 -Pt-Van) was prepared utilizing platinum ammonia bonds. Without S. aureus , a high S 2 O 8 2−/O 2 ECL intensity was achieved by the cooperative enhancements of RGO, AuNPs and hemin ("signal-on"). Then, when S. aureus existed, captured by aptamers, which further combined with MoS 2 -Pt-Van by the bio-recognition of vancomycin and bacterial cytoderm. As a result, a low ECL intensity was obtained by the highly quenching effect of MoS 2 -Pt-Van on the S 2 O 8 2−/O 2 ECL system ("signal-off"). The ECL intensity had a linear relationship with the logarithm of S. aureus concentration in a range of 1.5 × 102 to 1.5 × 108 CFU/mL, possessing the detection limit of 28 CFU/mL. In addition, this assay possessed excellent detection specificity, and could be applied to the analysis of S. aureus spiked in urine samples. Therefore, this strategy might become a potential alternative tool for bacteria detection in medical research and early clinical diagnosis. [ABSTRACT FROM AUTHOR]

In this work, an ultrasensitive electrochemiluminescence (ECL) biosensor was constructed using poly- L -lysine (PLL) as a novel co-reactant of luminol and poly(luminol/aniline) nanorods loaded reduced graphene oxide (PLA@rGO) as nanoprobe, which enable highly sensitivity detection of glutathione (GSH). To the best of our knowledge, it is the first time that PLL was used for the co-reactant of luminol. Notably, about a 5-fold enhancement was obtained compared with the individual PLA@rGO using GCE. Due to the remarkable quenching effect between the excited state of PLL and the reduced form of GSH in the ECL system of luminol/PLL, the ECL sensing platform exhibited wide linear ranges of 1.0 × 10−9–1.0 × 10−4 M and 1.0 × 10−4–1.0 × 10−2 M and a low detection limit of 7.7 × 10−10 M. Simultaneously, the biosensor was also successfully applied to detect GSH in human serum sample with high recoveries. Hence, this work would open a new platform for the wide application of PLL in immunoassay and various sensors. • A novel signal amplification strategy based on PLL as a novel co-reactant of luminol which enable sensitivity detection of GSH. • PLL with great stability and biological compatibility was used as co-reactant of luminol for the first time. • Notably, about a 5-fold enhancement was obtained compared with individual PLA@rGO using GCE. • The proposed ECL sensing platform was found to exhibit high sensitivity and wide dynamic range for the detection of GSH. [ABSTRACT FROM AUTHOR]

Abstract The simultaneous determination of two food colorants (cochineal (E-120) and erythrosine (E-127)) was achieved by means of excitation-emission fluorescence matrices and three-way PARAFAC decomposition together with the use of a calibration set that contained binary mixtures of both analytes. In the measured conditions, the amount of cochineal present in the sample affected the fluorescence signal of erythrosine since cochineal caused a quenching effect in the fluorescence of the other food additive. However, the signal of cochineal was not affected by the presence of erythrosine. A calibration line for erythrosine was built for each different concentration level of cochineal. The slopes of these regressions were different depending on the amount of quencher, whereas the intercepts were statistically equal to 0 at a 95% confidence level. The quantification of erythrosine was possible using the regression "amount of cochineal" versus "the slope of the calibration line for erythrosine". Using this procedure, the mean of the absolute values of the relative errors in prediction for mixtures of both colorants were 5.86% (n = 10) for cochineal and 4.17% (n = 10) for erythrosine. Both analytes were unequivocally identified by the correlation between the pure spectra and the PARAFAC excitation and emission spectral loadings. Pitted cherries in syrup were analyzed. Cochineal and erythrosine were detected in those cherries at a concentration of 185.05 mg kg−1 and 10.76 mg kg−1, respectively. These concentration values were statistically equal to the ones obtained with a HPLC/DAD method. Graphical abstract fx1 Highlights • Determination of two food colorants in cherries in syrup by EEM and three-way PARAFAC. • Cochineal was a quencher when erythrosine was measured by molecular fluorescence. • The fluorescence signal of cochineal was not affected by the presence of erythrosine. • A strategy was proposed to handle the quenching effect using three-way techniques. [ABSTRACT FROM AUTHOR]

Abstract The DArk Matter Particle Explorer (DAMPE), which is a Chinese space telescope for the precise measurement of high-energy electrons, gamma rays, and nuclei from deep space, was successfully launched on December 17, 2015. The DAMPE electromagnetic calorimeter made of bismuth germanium oxide (BGO) crystals can measure incident hadron energies from 50 GeV to 100 TeV. The calorimeter was tested with ion beams at CERN in 2015. The energy responses to ions from helium to argon are investigated. The result is reproduced by a Monte Carlo simulation based on Geant4 with two physics process models. It shows that the simulation results of a beam test are independent of the physics models adopted. Additionally, quenching effects of the BGO crystal on the ions are observed with this beam test. The quenching attenuations increase with the atomic number and were approximately 7% for boron and 40% for argon. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel polymeric mono-component intumescent flame retardant defined as PPMPNG was synthesized. • PPMPNG presented superior fire retardant efficiency for polyethylene. • PPMPNG could exert flame retardant effect in gas and condensed phase simultaneously. Abstract A novel polymeric mono-component intumescent flame retardant poly(piperazine methylphosphonic acid neopentylglycol ester) (PPMPNG) was synthesized from methylphosphonic acid, piperazine and neopentyl glycol. Its chemical structure was detailed characterized by Fourier transform infrared spectroscopy (FTIR), 13C and 31P solid-state nuclear magnetic resonance. PPMPNG was incorporated into polyethylene (PE) and the flame retardancy, thermal properties and flame retardant mechanism of materials were investigated. The samples with the thickness of 1.6 mm passed UL-94 V-0 rating during vertical burning tests and the limiting oxygen index was 25.6% when 23 wt% PPMPNG was introduced. The results of thermogravimetric analysis (TGA) showed that the addition of PPMPNG promoted the degradation and carbonization of materials at the beginning and improved the char residue amount and thermal stability of FR-PE at high temperature. Cone calorimeter tests indicated that the peak value of heat release rate was considerably reduced with the incorporation of PPMPNG. The flame retardant mechanism showed PPMPNG exerted isolation effect in condensed phased and quenched active free radical effect in gas phase. The combustion intensity was reduced and the flame was suppressed and even extinguished, thus a high efficiency for PE matrix was achieved. [ABSTRACT FROM AUTHOR]

This report outlines a highly sensitive and facile electrochemiluminescence (ECL) sensing platform based on a novel high-quantum-yield Au-nanocluster (AuNC) probe for glutathione (GSH) detection. Owing to the prominent quenching effect of GSH on the ECL of the AuNCs, the proposed ECL nanosensor showed a wide response to GSH in the ranges of 1.0 × 10 -9 –1.0 × 10 -5 M and 1.0 × 10 -5 –1.0 × 10 -1 M and a low detection limit of 3.2 × 10 -10 M. In addition, the proposed system exhibited good selectivity for GSH in the presence of other chemical/biological interferences. Moreover, since no further functionalization of AuNC-based sensor interface was necessary, together with the stability, high sensitivity and selectivity of the proposed nanosensor, this convenient approach was able to successfully detect GSH in both of human urine samples and blood samples with excellent recoveries, which indicated its promising application under physiological conditions. Of significant importance is that this study not only helps in gaining a better understanding of the applicability of the ECL properties of AuNCs, but also provides a new avenue for the design and development of ECL sensors based on the novel high-quantum-yield AuNC-based probe and other functional-metal-based NC probes. [ABSTRACT FROM AUTHOR]

The Dark Matter Particle Explorer (DAMPE) is a satellite-borne detector designed to measure high energy cosmic-rays and γ -rays. As a key sub-detector of DAMPE, the Bismuth Germanium Oxide (BGO) imaging calorimeter is utilized to measure the particle energy with a high resolution. The nonlinear fluorescence response of BGO for large ionization energy deposition, known as the quenching effect, results in an under-estimate of the energy measurement for cosmic-ray nuclei. In this paper, various models are employed to characterize the BGO quenching factors obtained from the experimental data of DAMPE. Applying the proper quenching model in the detector simulation process, we investigate the tuned energy responses for various nuclei and compare the results based on two different simulation softwares, i.e. GEANT4 and FLUKA. The BGO quenching effect results in a decrease of the measured energy by approximately 2.5% (5.7%) for carbon (iron) at ∼ 10 GeV/n and < 1 % above 1 TeV/n, respectively. Accordingly, the correction of the BGO quenching effect leads to an increase of the low-energy flux measurement of cosmic-ray nuclei. [ABSTRACT FROM AUTHOR]

A polymer imprinted with acrylamide (AM-MIP) was synthesized on the surface of graphene oxide by surface polymerization of propionamide (serving as a dummy template), methacrylic acid (as the functional monomer) and ethylene glycol dimethacrylate (the cross-linker). ZnS quantumdots (QDs) doped with Mn(II) ions were added to theAM-MIP to act as fluorescence source. The AM-MIP was characterized by infrared spectroscopy, scanning electron microscopy and X-ray powder diffraction, suggesting that the imprinted layer was successfully grafted onto graphene oxide. The fluorescence of the doped QDs is quenched when loading the AM-MIP with acrylamide (AM), and the quenching effect is much stronger than the non-imprinted polymer (AMNIP). Quenching follows Stern-Volmer kinetics. The combination of imprinting and fluorometric detection offer AM-IIP capability to accumulate trace AM before direct determination, omitting desorption and separation or other methods. The excitation and emission spectra of AM-MIP peak at 325 nm and 601 nm, respectively. Under optimal conditions, fluorescence drops linearly in the 0.5-60 µmol⋅L-1 acrylamide concentration range, and the detection limit is 0.17 µmol⋅L-1. The method has been applied to the determination ofAMin spiked water samples and gave recoveries in the range from 100.2 to 104.5%, with relative standard deviations in the 1.9 to 3.9% range. In our perception, the AM-MIP presented here is a promising fluorescent probe for the detection of trace acrylamide in food. [ABSTRACT FROM AUTHOR]

Kochia scoparia, also called broom seedlings, broom dishes and peacock pine, is an annual herb of genus Kockia in family chenopodiaceae. The seedlings of K. scoparia are wild vegetables with high protein, low fat and rich potassium and carotene. As a widely distributed plant in china, K. scoparia is eaten as traditional wild herbs. However, there is little research and development on its medicinal value. The N-trans-feruloyltyramine from K. scoparia was isolated and purified by silica gel column chromatography. The interavtion mechanism between N-trans-feruloyltyramine and bovine serum albumin(BSA)was investigated by UV and fluorescence spectrometry. The quenching constant, binding constant and binding sites were obtained by analyzing quenching data based on Stern-Volrner equation. The results showed that the fluorescence of BSA was quenched by N-trans-feruloyltyramine by a static quenching process strong interaction between N-trans-feruloyltyramine and BSA could be stored and transported by protein. The results of this experiment provide some theoretical information for the further development and medicinal value of Kochia scoparia resources. [ABSTRACT FROM AUTHOR]

The characterization of quantum dots (QDs) and their conjugates with bovine serum albumin was done using on-a-chip electrophoresis. Under optimal conditions, bioconjugated QDs were successfully separated from free QDs within ≈10 min. Influence of coupling agent on a quenching of QD fluorescence intensity caused by conjugation to a protein was studied. When using two-step procedure combining 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide with N-hydroxysulfosuccinimide, the highest quenching effect was notable. We showed that QDs and capillary electrophoresis on a chip can be applied as a sensitive technique for the detection of biological molecules. The characteristics of this method are simplicity, small sample and reagent requirements, and high efficiency of separation. Graphical abstract: [ABSTRACT FROM AUTHOR]

The estimation is obtained for the quenching time τl of the non-equilibrium orbital momentum of the electron that can be got after the excitation by the femtosecond optical pump. The quenching process of the l is supposed to be determined by the interaction of l with the crystal field and its deformations (phonons). The time τl is determined not only by the parameters of the crystal field but also by the speed of relaxation of the virtual phonon 1/τ(ω) with the frequency ω≈1/τl. Considering the frequency dependence of τ(ω) enlarges the estimated value of τl up to the microsecond scale. This value exceeds greatly the picoseconds times of the ultrafast magnetic dynamics (UMD) processes observed after the action of the femtosecond optical pump. This means that the results obtained in our work are not supposed to be compared with the experimental data on UMD. The presented description of the quenching of l is the solution of one of the auxiliary tasks that can be useful for construction of the UMD theory. [ABSTRACT FROM AUTHOR]

[Display omitted] • Tb-MOF as a potential sensing material for chloroquine phosphate recovered for multiple cycles. • The quenching mechanisms between Tb-MOF and chloroquine phosphate from many aspects investigated. • The sensor used for the visual detection of chloroquine phosphate in serum. A novel three-dimensional (3D) anionic anhydrous metal − organic framework (MOF), {[NH 2 (CH 3) 2 ]·[Tb(pdca) 2 ]} n (Tb-MOF ; H 2 pdca = 2,5-pyridinedicarboxylic acid) has been triumphantly fabricated and structurally characterized. The obtained Tb-MOF displays good stability in some common solvent systems and high temperature environments. The luminescence properties of Tb-MOF are investigated by fluorescence spectra, and the results exhibit superb characteristic emission of Tb3+ ions, which lay a foundation for exploring the fluorescence sensing application of the material. More importantly, based on competitive absorption and dynamic quenching, Tb-MOF can be applied to detect chloroquine phosphate (CQ) used for the treatment of COVID-19 and malaria, showing high sensitivity and fast response speed in the sensing process. Notably, the specific quenching effect between Tb-MOF and CQ in the serum system without interference from other components, demonstrating the practical application potential of Tb-MOF. [ABSTRACT FROM AUTHOR]

A spectrofluorimetric approach that is sensitive, simple, validated, and cost-effective has been proposed for the estimation of amlodipine (AML) and perindopril (PER) in their bulk powders, pharmaceutical formulations, and spiked human plasma. The recommended approach utilized the quantitative quenching effect of the two cited drugs on the fluorescence intensity of erythrosine B, as a result of complex binary reactions among each drug with erythrosine B at pH 3.5 (Teorell and Stenhagen buffer). The quenching of erythrosine B fluorescence was recorded at 554 nm after excitation at 527 nm. The calibration curve was detected in the range 0.25-3.0 μg ml -1 , with a correlation coefficient of 0.9996 for AML, and 0.1-1.5 μg ml -1 , with a correlation coefficient of 0.9996 for PER. The established spectrofluorimetric approach was validated for the estimation of the cited drugs with high sensitivity regarding International Council on Harmonization guidelines. Therefore, the established approach could be utilized for quality control of the cited drugs in their pharmaceutical formulations., (© 2023 John Wiley & Sons Ltd.)

Automatic, inexpensive, simple and sensitive methods for DNA sensing and quantification are highly desirable for biomedical research. The rapid development of both the fundamentals and applications of electrochemiluminescence (ECL) over the past years has demonstrated its potential for analytical and bio-analytical chemistry. This paper reports the quenching effect of DNA on the ECL of luminol and the further development of a DNA sensing device. With the pre-functionalization by a composite of carbon nano-tubes (CNTs) and Au nanoparticles (AuNPs), the sensor provides a novel and valuable label-free approach for DNA sensing. Here the ECL intensity was remarkably decreased when more than 1.0 × 10−12 molar of DNA were adsorbed on the sensor. Linearity of the DNA amount with the reciprocal of ECL intensity was observed. A saturated sensor caused a 92.8% quenching effect. The research also proposes the mechanism for the quenching effect which could be attributed to the interaction between luminol and DNA and the elimination of reactive oxygen species (ROSs) by DNA.

In this work, a novel reduction-accelerated quenching of manganese porphyrin (MnPP) based signal-off cathode photochemical (PEC) biosensor by using Au nano-flower/organic polymer (PTB7-Th) heterojunction as platform was proposed for ultrasensitive detection of Hg2+. Firstly, the photoactive PTB7-Th with Au nano-flower on electrode could form a typical Mott-Schottky heterojunction for acquiring an extremely high cathode signal. Meanwhile, the presence of target Hg2+ could bring in the formation of T-Hg2+-T based scissor-like DNA walker, which thus activated efficient Mg2+-specific DNAzyme based cleavage recycling to shear hairpin H2 on electrode to exposure abundant trigger sites of hybridization chain reaction (HCR) for in-situ decoration of quencher MnPP. Here, besides the steric hinderance and light competition effect of MnPP decorated DNA nanowires attributing to signal decrease, we for the first time testified the MnPP reduction-accelerated quenching that constantly consumed the photo-generated electron by using cyclic voltammetry (CV). As a result, the proposed biosensor had excellent sensitivity and selectivity to Hg2+ in the range of 1 fM-10 nM with a detection limit of 0.48 fM. The actual sample analysis showed that the biosensor could reliably and quantitatively identify Hg2+, indicating an excellent application prospect in routine detection. [Display omitted] • The PEC biosensor provided an excellent application prospect in actual sample analysis. • The schottky heterojunction generated an extremely high initial photocathode signal. • We firstly testified MnPP reduction-accelerated quenching toward PTB7-Th. • The DNA walker activated Mg2+ based cleavage recycling for signal amplifying. [ABSTRACT FROM AUTHOR]

[Display omitted] • A spectrofluorometric method for analysis of rivaroxiban. • Acetoxymercuric fluorescein was quenched by rivaroxiban. • The method was validated for the estimation of rivaroxiban. A simple, precise and inexpensive spectrofluorimetric method has been developed for assay of rivaroxaban raw material and its tablets. The method depends on the quenching effect of rivaroxaban on the fluorescence intensity of acetoxymercuric fluorescein (AMF). Parameters that may affect the reaction such as pH, AMF solution concentration, reaction time and diluting solvents were studied and optimized. The proposed method was applied for determination of rivaroxaban in tablets with percentage recovery of 100.4 ± 0.28 , and in organic extract of spiked plasma samples with percentage recovery of 98.40 ± 1.08. The developed method was validated according to ICH guidelines in terms of accuracy, precision, linearity, range, limit of detection (LOD) and limit of quantification (LOQ). [ABSTRACT FROM AUTHOR]

The series of Bi co-doped YPO : Eu nanophosphors were successfully synthesized by the slow evaporation method. Bi-doped and un-doped YPO : Eu phosphors were characterized by using powder X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Photoluminescence (PL) properties and decay time of phosphors were studied at room temperature. The YPO : Eu and Bi exhibit enhancement in PL intensity and quenched at 0.5 mol% of Bi ions. [ABSTRACT FROM AUTHOR]

Tritium content is very low in most of the natural water, and it is necessary to be concentrated before measurement. Polymerization (SPE) membrane electrolysis enrichment method is important in the concentration of low level tritium content for natural water samples. But impurity ions concentrate from water samples and SPE device in the process of water samples treatment cause acidification, resulting in the colour quenching in the mixture of concentrated liquid and liquid scintillation. Consequently, the radioactive activity of tritium will be lower than the reference value. Experimental for Solid polymer electrolyte method,study the impurity ions concentrate from water samples failed to remove completely and the aging of SPE device,the acidification pH and the electrical conductivity of samples in the process of samples treatment on the influence of the quenching. Use the ion and acid-base hybrid exchange resin column separate impurity ions once again for high electrical conductivity and acidification pH samples; adjust the pH value to the neutral after the concentration of the electrolyte with Ammonia to effectively reduce the quenching cause by impurity ions from the aging of SPE device, avoid quenching significantly reduced the low tritium natural water samples counting. [ABSTRACT FROM AUTHOR]

Fluorescence-based probes exhibit apparent superiority in high sensitivity, selectivity and easy operation. As a typical representative of zeolitic imidazolate frameworks (ZIFs), highly porous ZIF-8 has attracted intense interests because of its potential applications. In this work, the organic dye Rhodamine 6G (R6G) loaded ZIF-8 nanocomposites were prepared and well characterized by transmission electron microscope (TEM), powder X-ray diffraction (PXRD) and N 2 adsorption. The R6G loaded ZIF-8 (R6G@ZIF-8) nanocomposites exhibit intense luminescence with wide wavelength band in the visible light region. The luminescent detections of metal ions, anions, organic small molecules and polyoxometalates were fully studied using the as-synthesized R6G@ZIF-8 nanocomposites as sensory materials. Strikingly, the luminescent detections indicate that R6G@ZIF-8 nanocomposites are capable of highly selective sensing of Fe 3+ , highly toxic Cr 6+ and organic aniline with a low detection limit of 5 μM, 50 μM and 5 mM, respectively. More significantly, luminescence quenching and recovery tests demonstrate that R6G@ZIF-8 nanomaterials are reusable for the detections of Fe 3+ , Cr 6+ and organic aniline. [ABSTRACT FROM AUTHOR]

Novel CdTe/ZnS quantum dot (QD) probes based on the quenching effect were proposed for the simple, rapid, and specific determination of ammonium in aqueous solutions. The QDs were modified using 3-mercaptopropionic acid, and the fluorescence responses of the CdTe/ZnS QD probes to ammonium were detected through regularity quenching. The quenching levels of the CdTe/ZnS QDs and ammonium concentration showed a good linear relationship between 4.0 × 10−6 and 5.0 × 10−4 mol/L; the detection limit was 3.0 × 10−7 mol/L. Ammonium contents in synthetic explosion soil samples were measured to determine the practical applications of the QD probes and a probable quenching mechanism was described. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The flame-retardant polylactic acid (PLA) has been prepared via mixing the flame retardant TGIC-DOPO derived from phosphaphenanthrene and triazine groups into matrix. The flame retardancy of TGIC-DOPO/PLA composites was characterized using the limiting oxygen index (LOI), vertical burning test (UL94), and cone calorimeter test. Results reveal that the 10%TGIC-DOPO/PLA composite obtained 26.1% of LOI and passed UL94 V-0 rating. The flame-retardant mechanism of PLA composites was characterized via thermogravimetric analysis (TGA), pyrolysis gas chromatography/mass spectroscopy, and TGA-Fourier transform infrared. It discloses that TGIC-DOPO promoted PLA decomposing and dripping early, and it also released the fragments with quenching and dilution effects. These actions of TGIC-DOPO contribute to reducing the burning intensity and extinguishing the fire on droplets, thus imposing better flame retardancy to PLA. When TGIC-DOPO was partly replaced by melamine cyanuric with dilution effect and hexa-phenoxy-cyclotriphosphazene with quenching effect in composites respectively, the results confirm that TGIC-DOPO utilize well-combination in dilution effect and quenching effect to flame retard PLA. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]