Chemiluminescence Intensity Research Articles

An experimental investigation into the wildland fire burning characteristics of loblolly pine needles

Wildland fires present a threat to both the environment and to homes and businesses in the wildland urban interface. Understanding the behavior of wildland fires is crucial for developing informed risk management techniques, such as prescribed burning, to prevent uncontrolled fires, which devastate communities globally. In this work, an optically accessible facility was developed combining traditional and optical diagnostic techniques to study the combustion of wildland fuels. This facility was then used to study the burning characteristics of loblolly pine needles (Pinus taeda). Mass loss rate, flame temperature, propagation rate, flame geometry, and OH* chemiluminescent flame intensity were measured for fuel loadings of 0.98, 1.31, and 1.63 kg/m2. Mass loss rate increased linearly with fuel loading. The flame propagation rate increased slightly with fuel loading while approaching an asymptotic value. The flame height and surface area increased more significantly with fuel loading, but also approached asymptotic values. Flame depth increased slightly with fuel loading, and throughout the duration of the test. The flame intensity and flame temperature did not change significantly with fuel loading.

A sensitive biosensor for glucose determination based on the unique catalytic chemiluminescence of sodium molybdate

Chemiluminescent (CL) reaction between hydrogen peroxide (H2O2) and luminol was dramatically enhanced by sodium molybdate (Na2MoO4) for 284-fold. CL mechanism investigation indicated that Na2MoO4 increased the production of hydroxyl radical (•OH) and superoxide anion (•O2−) in the H2O2-luminol system, which could attribute to the enhanced-CL intensity and gave us new insights into the CL-enhanced property of Na2MoO4. The CL intensity of Na2MoO4-H2O2-luminol system increased with the concentration of H2O2, based on which, a convenient and sensitive CL determination method could be developed for H2O2 in the concentration ranging from 0.5 to 60 μmol/L, with a detection limit of 0.25 μmol/L. Combining with glucose oxidase, the Na2MoO4-H2O2-luminol system could also be applied for glucose detection. Glucose in human serum has been successfully detected with satisfied recoveries in the range of 96.7 % to 105.4 %.

Lucigenin-pyrogallol chemiluminescence for the multiple detection of pyrogallol, cobalt ion, and tyrosinase.

Developing new, cheap, sensitive and selective chemiluminescence (CL) systems with multiple detection properties is still a big challenge for biological and environmental applications. Here, we report a new CL system having multiple detection applications (environmental and biological). The developed lucigenin-pyrogallol system gave an enhancement (190 times) over the conventional lucigenin-H2O2 CL system. Cobalt ion and tyrosinase can inhibit lucigenin-PG CL intensity. Based on these phenomena, we have developed new CL methods for the detection of pyrogallol (LOD = 0.94 μM), lucigenin (LOD = 0.42 μM), cobalt (LOD = 68 nM), and tyrosinase (LOD = 1.8 μg/mL). Furthermore, the developed system gave excellent recoveries in real samples within the range of 93.59–103.12% for the assay of pyrogallol, Co2+ and tyrosinase in coffee, lake water, and human plasma, respectively.

Experimental verification of cylindrical air-breathing continuous rotating detonation engine fueled by non-premixed ethylene

An especial air-breathing continuous rotating detonation engine without a centerbody is proposed to reduce energy loss and simplify the structure, which is analogous to a typical scramjet combustor with the cavity. Non-premixed ethylene/air rotating detonation experiments are performed in a direct-connect experimental facility with an air inflow of 860 K total temperature (Ma 2.02). Two combustion modes (continuous rotating detonation and deflagration mode) are discovered with varying equivalent ratio (ER). A proper accumulation layer of the combustible mixture in the cavity re-circulation region attaching the outer wall is critical for rotating detonation realization. The average propagation velocity of the detonation wave is 1297.1 m/s (78.5% C-J velocity) at ER = 0.64 with the combustor pressure of 230 kPa. Its motion of the reaction zone is quantitatively verified to be rotating through the integral of chemiluminescence intensity. Besides, it is confirmed by the optical observation that deflagration could also self-sustain in the short combustor with the axial-moving flame. The combustor pressure of deflagration mode can reach 220 kPa with ER = 0.56. Though the combustor pressure of detonation is slightly higher than that of deflagration, the impact of combustor high-pressure on the inflow of detonation mode is much stronger through the induced oblique shock wave.

An efficient chemiluminescence system based on mimic CuMOF/Co3O4 nanoparticles composite for the measurement of glucose and cholesterol

The development of novel non-enzyme mimics for (bio)sensing applications is of great practical importance. Herein, an efficient chemiluminescence (CL) system is presented according to the significant mimetic behavior of the copper metal-organic framework decorated with cobalt oxide nanoparticles (Co3O4@CuMOF). The catalytic activity of nanocomposite was proved by its strengthening effect on the CL emission of rhodamine B (RB)-hydrogen peroxide (H2O2) reaction. More documents were also obtained using colorimetric and fluorometric peroxidase substrates. The presence of Cu and Co in the Co3O4@CuMOF structure, as well as the high porosity and great surface area of the obtained composite, was responsible for the observed synergetic catalytic activity. The Michaelis-Menten constant (Km) for the composite (0.108 mM) was remarkably lower than that of pristine CuMOF and Co3O4 NPs, illustrating its superior affinity towards H2O2. A linear correlation was found between the CL intensity and H2O2 concentration in the extensive range of 1–250 nM, with a detection limit (3S) of 0.244 nM. Furthermore, the developed system was exploited as a reliable sensing device for individual measurement of cholesterol and glucose after their enzymatic oxidations. The obtained data verified the high sensitivity and selectivity of the probe, which could be linked to the presence of high-performance Co3O4@CuMOF and the accompanying enzymes, respectively. The designed method was appropriately applied to measure cholesterol and glucose levels in human serum samples, and its accuracy was validated by analyzing the standard materials.

Distributed combustion of diesel–butanol fuel blends in a mixture temperature-controlled burner

Butanol is a promising candidate to increase the share of renewable fuels in our liquid fuel portfolio for industry and transportation. The combustion of four B0-B50 diesel fuel-n-butanol blends was investigated in a Mixture Temperature-Controlled burner, a novel archetype of turbulent swirl burners for ultra-low emissions to provide data on the effect of butanol blending for steady-operating applications. Stable combustion of blended fuels was limited to an equivalence ratio of 0.76 in our burner, which is a notable drawback compared to that of diesel fuel in this test system. Distributed flames feature low luminosity and single-digit CO and NOX emissions in ppm at 15% O2 level, the representative for gas turbines, fulfilling all the current NOX regulations with 86% margin on average. The CO emission was inferior in all cases. The chemiluminescent intensity of OH* was sufficient for evaluation at all flames except for distributed combustion, which is the favorable flame type. The acoustic spectrum of various fuels under identical conditions was highly similar, concluding easy interchangeability from a combustion acoustics point of view. Moreover, the noise of distributed combustion was 10 dB lower than that of straight flames for all fuels and conditions.

Cytoprotective and Antioxidant Effects of Meconic Acid in Model Systems.

We studied the antioxidant and cytoprotective effects of meconic acid in the model systems. Meconic acid, similar to commercial drug Mexidol, reduced the intensity of chemiluminescence in the model system of yolk lipoproteins. Meconic acid also reduced the toxic effect of glutamate on neurons in the primary cerebellar culture, but had no effect on cell viability under normal conditions.

Determination of thiourea by terbium (III)/ prulifloxacin sensitized potassium permanganate-sulfite chemiluminescence with quenching method

Based on the thiourea quenching of the chemiluminescence of Tb3+/ prulifloxacin (PUFX) sensitized KMnO4-Na2SO3 system, a convenient and rapid chemiluminescence method for the determination of thiourea was proposed. The reaction between KMnO4 and Na2SO3 brought only weak chemiluminescence, but the chemiluminescence increased sharply in the presence of sensitizer Tb3+/ PUFX. Addition of thiourea can prevent the reaction between KMnO4 and Na2SO3, thus the chemiluminescence intensity was significantly decreased. Under the optimum conditions, the calibration graphs for thiourea were linear in the range of 1.0 × 10-7 to 4.0 × 10-5 mol•L-1. The limit of detection was 6.4 × 10-8 mol•L-1. The method was applied satisfactorily to the determination of thiourea in tap water, lake water and rice noodles and the spiked recoveries were between 104.7 ~ 113.4%. The possible mechanism of sensitization and quenching was also proposed.

Chemiluminescence enhanced by cerium-doped LaF3 nanoparticles through electron-hole annihilation

In this paper, cerium-doped LaF3 nanoparticles (LaF3:Ce NPs) were synthesized and applied in enhancing chemiluminescence (CL) process of NaIO4–H2O2 system. The CL intensity was enhanced 42 times compared to that of NaIO4–H2O2 system without LaF3:Ce NPs. The CL mechanism was systematically investigated and accounted by the annihilation between electron-injected and hole-injected LaF3:Ce NPs. Experimental conditions were optimized to obtain the optimum CL. This work introduced a new pathway for enhancing traditional luminescent process through developing advanced nanomaterials.

A High Selective Chemiluminescent Probe Derived fromIso‐luminol Enabling High Sensitive Determination of Ferrous Ions in the Environmental Waters

Main observation and conclusionA new chemiluminescence (CL) reagent named 4‐amino‐5‐thiocyanato‐phthalyl‐hydrazine (iso‐luminol‐SCN) is synthesized by the bromide‐mediated substitution reaction ofiso‐luminol with sodium thiocyanate in dimethyl formamide (DMF) at room temperature. Strong CL is observed foriso‐luminol‐SCN oxidized by hydrogen peroxide (H2O2) in the presence of Fe2+, with the CL intensity strongly depending on the concentration of Fe2+and being hardly interferred by other common metal ions. Based on this fact, a flow injection CL method is established for the high sensitive and selective determination of Fe2+. The CL intensity was linearly correlated with the concentration of Fe2+in the range of 1.0 × 10–8mol·L–1to 1.0 × 10–5mol·L–1following the equation CLnet= 166.3c+ 57.7 (c, ×10–6mol·L–1;n= 7;R2= 0.9988). The detection limit is calculated to be 3.2 × 10–9mol·L–1Fe2+based on the 3S0/K principle. The relative standard deviation (RSD) was 3.7% for 1.0 × 10–6mol·L–1Fe2+(n= 11), a support for the precision of Fe2+measurement. The recoveries of Fe2+were obtained in the range of 98.8%—101.6% in three real water samples, showing the applicability and reliability by the proposed method. The possible CL mechanism is proposed based on the kinetic characteristic of the CL reaction and the CL spectrum.

Bovine serum albumin-encapsulated gold nanoclusters-Cu2+ synergize and promote calcein chemiluminescence for glutathione detection in human whole blood

In this paper, bovine serum albumin-encapsulated gold nanoclusters-Cu2+ (Au@BSA NCs-Cu2+) were found to induce chemiluminescence (CL) of calcein and hydrogen peroxide (H2O2) since the synergy and promotion of Au@BSA NCs-Cu2+. The weak CL of the calcein-H2O2 system in alkaline solution was enhanced by Au@BSA NCs-Cu2+ about 34 times. When glutathione (GSH) was added into the new calcein-H2O2-Au@BSA NCs-Cu2+ system, the CL intensity could be decreased. Based on these findings, a GSH CL assay was developed, and the assay displayed a good linear relationship ranging from 0.50 to 6.00 mmol·L−1, with a detection limit of 0.29 mmol·L−1. Finally, the CL method reported here was successfully used to detect the GSH in human whole blood samples.

The chemiluminescence of AgInS2 quantum dots and its application as a sensing platform for glutathione assay

Herein, we prepared highly luminescent water-soluble AgInS2 quantum dots (AIS QDs) by a green and simple hydrothermal method and characterized them by various spectroscopic and microscopic techniques. The chemiluminescence (CL) of AIS QDs induced by direct chemical oxidation was investigated. It was found that NaIO4 in alkaline solution elicits a remarkable CL from these QDs. The CL was proved to be originated from the excited-state QDs, produced during the reaction. Further studies revealed that the addition of glutathione (GSH) to NaIO4-AIS QDs system effectively increased the CL intensity. This was employed as a sensing platform for sensitive assay of GSH. In the optimized conditions, the relation between the CL intensity and GSH concentration was linear in the range of 1.0 × 10−9 mol L−1 to 5.0 × 10−6 mol L−1 with a detection limit of 2.8 × 10−10 mol L−1. To evaluate the practical usefulness of the assay, the established technique was applied to the analysis of human plasma.

New chemiluminescent method of levofloxacin and ofloxacin determination based on terbium (III)-sensitized fluoroquinolone-KBrO3 reaction.

Fluoroquinolones can be oxidized with some agents, in this study selected fluoroquinolones (levofloxacin, ofloxacin, ciprofloxacin, norfloxacin, pefloxacin and enrofloxacin) were oxidized with potassium bromate in the presence of terbium (III) ions. According to the kinetic and spectral analysis of chemiluminescence emitted by the above systems, the terbium (III) ions were the only emitter. The excitation of the lanthanide ion was a result of the process of energy transfer from the products of fluoroquinolones oxidation to Tb(III) ions. The highest intensity of chemiluminescence was obtained for levofloxacin and ofloxacin containing an alkoxy substituent at C-8 in the quinoline ring. The chemiluminescence intensity was correlated linearly (r= 0.9994) with the concentration of ofloxacin (or levofloxacin) in the range 1 × 10-6 to 4 × 10-5 mol L-1 ; the detection limit was 3 × 10-7 mol L-1 for both fluoroquinolones. In the optimized conditions, the chemiluminescence of the levofloxacin (or ofloxacin)-Tb(III)-KBrO3 -H2 SO4 systems was used to determine these compounds in a mixture of fluoroquinolones and in pharmaceuticals.

Experimental research on using CO2-Ar microjets to control liquid fuel combustion instability and pollutant emission

Combustion instability has become an obstacle to the development of modern gas turbines. In this study, four categories of jet tubes inject CO2-Ar mixture to the flame root at different total injection volume flow rates and mixing ratios. These jets do not change the dominant combustion instability frequency, yet the large flow rate jets can significantly weaken the pressure and the heat addition oscillations. The tube type or the CO2-Ar volume fraction in the jets has no apparent influence on the control efficacy. When the total jet volume flowrate reaches 10 L/min, the maximum amplitude reduction ratio of pulsating pressure and CH∗ chemiluminescence intensity is 90% and 89%, respectively. Meanwhile, the jets caused a significant drop in the flame temperature, and the NOx emission was reduced by at least 35%. However, the side effect of the jets is that the flame is on the verge of blowing out, and the CO emission increases sharply. The higher the volume fraction of CO2 in the jets, the more likely it is to generate CO. Designers need to compromise the impact of jets on the safety and cleanliness of the combustors.

Removed heavy metal ions from wastewater reuse for chemiluminescence: Successive application of lignin-based composite hydrogels

The novel sulfomethylated lignin-grafted-polyacrylic acid (SL-g-PAA) hydrogel was fabricated in this work via a facile and green synthetic strategy for the efficient removal of heavy metal ions from wastewater, and then successively reused for chemiluminescence (CL). The sulfomethylation of lignin was first performed to improve its water solubility and introduce numerous active sites for adsorption of heavy metal ions. The as-synthesized SL-g-PAA hydrogel with high content of lignin exhibited the highly efficient and rapid removal of various metal ions from simulated wastewater. More importantly, the spent hydrogel (M2+@SL-g-PAA) after adsorption was reused for the first time to develop a new CL system by an ingenious strategy, in which these metal ions adsorbed on M2+@SL-g-PAA act as heterogeneous catalytic sites to catalyze the CL reaction between N-(4-aminobutyl)-N-ethylisoluminol (ABEI) and H2O2. The resultant CL system displayed high CL intensity and long duration time, which could be observed by naked eye in the dark and lasted for > 24 h. The combination of facile fabrication process, renewable raw materials, and ingenious strategy for successive application in adsorption and CL endows this lignin-based composite hydrogel with a great potential for application in wastewater treatment, biological imaging and cold light sources.

An activatable chemiluminescence probe based on phenoxy-dioxetane scaffold for biothiol imaging in living systems

Quantification of biothiols in living systems is essential to understand their biological applications. Here, we developed two activatable chemiluminescence probes (SHCL and NCCL) and investigated their utility in the bioimaging of intracellular biothiols by directly tethering 2,4-dinitrobenzenesulfonyl to the hydroxyl group of phenoxy-dioxetane. The design of these two probes differed in substituents of phenol-dioxetane, i.e., SHCL contained the ortho chlorine, whereas NCCL had the para hydroxymethyl. Upon glutathione (GSH) cleavage, both probes emitted significantly “turn-on” chemiluminescent signals. However, the chemiluminescence intensity based on NCCL declined with increasing GSH level above 5 mM, while SHCL exhibited much higher chemiluminescent intensity and a wider concentration range (0.5 μM-50 mM), which was much more suitable for sensing endogenous biothiols. We further demonstrated that chlorine substitution in SHCL played an important role in bioimaging owing to the halogen effect, providing a lower pKa value and significant enhancement of the chemiluminescent emission. SHCL imaged the biothiols effectively in tumor cells and tumor-bearing mice. Additionally, this novel chemiluminescence probe can be easily used to evaluate the in vitro activity of acetylcholinesterase. Overall, we anticipate that SHCL may provide a facile and intuitive tool for studying the role of biothiols in diseases.

Simultaneous Determination of the Chemical (kr ) and the Physical (kq ) Quenching Rate Constants of Singlet Oxygen in Aqueous Solution by the Chemiluminescence-quenching Method.

This work reports a novel and visual method for the simultaneous determination of the chemical (kr ) and the physical (kq ) quenching rate constants of singlet oxygen (1 O2 ,1 ∆g ) in aqueous media. It is based on the disruption, by a water-soluble substrate S, of the 1 O2 chemiluminescence (CL) generated by the H2 O2 /Na2 MoO4 catalytic system. A mathematical analysis of the CL signal at 1270 nm vs time provides separately the overall (kr + kq ) and the chemical (kr ) quenching rate constants. In ordinary water (H2 O), 1 O2 lifetime is short and the CL intensity is weak allowing solely the investigation of very reactive substrates for which (kr + kq ) > 3 × 106 m-1 s-1 while, in D2 O, 1 O2 lifetime is significantly longer lifetime and the CL signal is much stronger allowing the study of poorly reactive substrates for which (kr + kq ) > 4 × 105 m-1 s-1 . The method has been successfully tested on a series of anionic and nonionic water-soluble naphthalene derivatives commonly used as bio-compatible 1 O2 carriers. The obtained kr and kq values are in good agreement with the values determined by conventional techniques, namely, flash photolysis and competitive kinetics with a reference quencher.

Non-invasive and accurate readout of superoxide anion in biological systems by near-infrared light

Infectious and inflammatory diseases involve superoxide anion (O2•–) production. Real-time and non-invasive evaluation of O2•– in intact biological systems has been a significant challenge in biology and medicine. Here, I report that an advanced near-infrared chemiluminescent probe, MCLA-800, enables reliable non-invasive optical readout of O2•–ex vivo and in vivo. MCLA-800 allowed highly selective and sensitive monitoring of O2•– in undiluted human whole blood ex vivo. For the first time, the use of MCLA-800 revealed two reproducible types of O2•– production in response to stimulation by unopsonized zymosan particles of Saccharomyces cerevisiae, that is, slow response (S-type) and fast response (F-type), specific to each individual. O2•– production was synchronized with myeloperoxidase (MPO) activation in the former type but not in the latter. Moreover, as new findings, MCLA-800 chemiluminescence demonstrated that the chemiluminescence intensity–time properties of formyl-methionyl-leucyl-phenylalanine (fMLP)- or phorbol 12-myristate 13-acetate (PMA)-induced O2•– production and MPO activity were independent of S- and F-type zymosan-induced MCLA-800 chemiluminescence whole blood and that PMA-induced MPO activation synchronized with PMA-induced O2•– production in S- and F-type zymosan-induced MCLA-800 chemiluminescence whole blood, but fMLP-induced MPO activation did not synchronize with fMLP-induced O2•– production in both of S- and F-type blood. Furthermore, MCLA-800 spatiotemporally allowed non-invasive and clear in vivo imaging of O2•– in animal models of acute dermatitis and focal arthritis. Therefore, MCLA-800 could be possibly applied in various advanced diagnostic techniques.

Mixing during Trapping Enabled a Continuous-Flow Microfluidic Smartphone Immunoassay Using Acoustic Streaming.

Smartphone-enabled microfluidic chemiluminescence immunoassay is a promising portable system for point-of-care (POC) biosensing applications. However, due to the rather faint emitted light in such a limited sample volume, it is still difficult to reach the clinically accepted range when the smartphone serves as a standalone detector. Besides, the multiple separation and washing steps during sample preparation hinder the immunoassay's applications for POC usage. Herein, we proposed a novel acoustic streaming tweezers-enabled microfluidic immunoassay, where the probe particles' purification, reaction, and sensing were simply achieved on the same chip at continuous-flow conditions. The dedicatedly designed high-speed microscale vortexes not only enable dynamic trapping and washing of the probe particles on-demand but also enhance the capture efficiency of the heterogeneous particle-based immunoassay through active mixing during trapping. The enriched probe particles and enhanced biomarker capture capability increase the local chemiluminescent light intensity and enable direct capture of the immunobinding signal by a regular smartphone camera. The system was tested for prostate-specific antigen (PSA) sensing both in buffer and serum, where a limit of detection of 0.2 ng/mL and a large dynamic response range from 0.3 to 10 ng/mL using only 10 μL of sample were achieved in a total assay time of less than 15 min. With the advantages of on-chip integration of sample preparation and detection and high sensing performance, the developed POC platform could be applied for many on-site diagnosis applications.

Chemiluminescence signature of premixed ammonia-methane-air flames

This paper reports on the chemiluminescence footprint of premixed ammonia-methane-air flames. The chemiluminescence spectrum of laminar twin-flames stabilized with a counterflow burner were measured between 200 and 457 nm for large ranges of equivalence ratio (0.60 ≤ ϕ ≤ 1.30), ammonia fraction (pure methane to pure ammonia), and strain rate (55/s ≤ a ≤ 300/s). Relevant excited radicals were identified, namely, NO*, OH*, NH*, CN*, CH*, and CO2* and evolutions of their chemiluminescence intensity were analyzed as a function of equivalence ratio, ammonia fraction, and strain rate. These measurements produced an unprecedented database on the chemiluminescence of ammonia-methane-air flames, which could be used in the future for model validation. A total of 15 ratios of chemiluminescence intensity were also considered and 5 ratios showing promise for the development of chemiluminescence-based flame sensors were identified. The CN*/OH* ratio is a potential surrogate for equivalence ratio even if the ammonia fuel fraction in the fuel blend is not known accurately – as long as it exceeds 0.3 by volume. The CN*/NO* ratio is another possible surrogate for equivalence ratio if the ammonia fraction in the fuel blend is below 0.5. The OH*/CH* ratio, often used to sense equivalence ratio in hydrocarbons flames, is not recommended for ammonia-methane flames. The NH*/CN* ratio is a potential surrogate for the ammonia fraction in the fuel blend if equivalence ratio is larger than ϕ = 0.7 and if the ammonia fraction in the fuel blend is below 0.4. Other ratios may be combined to provide a simultaneous measure of equivalence ratio and ammonia fraction in the fuel blend with an extended range of validity, for example NH*/OH* and CN*/NH*.