Chemiluminescence Intensity Research Articles

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*.

Monocyte Chemiluminescence Traits in Gastric Cancer

Aim. A study of monocyte chemiluminescent activity at variant stages of gastric cancer.Materials and methods. The study enrolled 90 gastric cancer patients and 70 healthy donors. Spontaneous and induced chemiluminescence in monocytes was assessed for 90 min with a “BLM 3607” 36-channel chemiluminescence analyser (Russia). Opsonized zymosan-induced chemiluminescence enhancement was measured as a ratio of the areas under the induced vs. spontaneous chemiluminescence curves, the activation index. Statistical significance was estimated with the Mann—Whitney criterion (p < 0.05).Results. The maximal spontaneous monocyte chemiluminescence intensity significantly decreased in stage IV gastric cancer patients compared to the control cohort (p = 0.035). Time to maximum in spontaneous chemiluminescence increased in all gastric cancer patients vs. control (p = 0.001), and in stage IV gastric cancer vs. stage I patients (p = 0.043). The areas under a curve in spontaneous and induced monocyte chemiluminescence increased in all gastric cancer patients vs. control (p = 0.001), and in stage IV gastric cancer vs. stage I patients (p = 0.037). The activation index was higher in all gastric cancer cases compared to control (p = 0.001).Conclusion. All patients with gastric adenocarcinoma, irrespective of the stage, revealed changes in the monocyte chemiluminescence activity, i.e. a longer time to maximum in spontaneous chemiluminescence and larger area under the curve of spontaneous and induced chemiluminescence, the activation index. Maximal monocyte spontaneous chemiluminescence intensity diminished in stage IV gastric cancer compared to the control cohort. Immune activity reflected in monocyte chemiluminescence correlates with the stage of gastric adenocarcinoma.

CuS nanoparticles-enhanced luminol-O2 chemiluminescence reaction used for determination of paracetamol and vancomycin

A new chemiluminescence (CL) method was proposed to measure two widely used drugs, including paracetamol (PCM) and vancomycin (VAN). The CL reaction used was the CuS nanoparticles (CuS NPs)-luminol-O2 system. In this system, CuS NPs played the role of catalyst and increased the CL intensity. CuS NPs were easily synthesized by quick-precipitation. CuS NPs were characterized by spectroscopic techniques, and the mean size of NPs was estimated to be about 9 nm. In the developed CL methods, PCM and VAN decreased the CL intensity. In the proposed method, the linear concentration ranges were 4.0 × 10−5–4.0 × 10−4 mol L-1 of PCM and 2.0 × 10−5–6.0 × 10−4 mol L−1 of VAN. The limit of detections were 2.9 × 10-5 mol L-1 and 8.9 × 10-6 mol L-1 for PCM and VAN, respectively. The relative standard deviations (RSD) of the CL method were 2.99 and 4.31 (n = 6) for the determination of 3.0 × 10−4 mol L−1 PCM and VAN, respectively. It was also shown that the CL methods can measure PCM and VAN concentrations in various real samples.

(Invited) A Soft-Crystal Chemiluminescence System: Luminescence Property of Adamantylideneadamantane 1,2-Dioxetanes Conjugated with a Fluorophore

Chemiluminescence (CL) produces photon by a chemical reaction of a CL substrate to give a product in the excited state. Because emitted photons are readily detectable, CL is a powerful tool to monitor a chemical event in an analyte. In the materials science, CL will be useful to analyze an event at the molecular level in a solid material for developing functional devises. For instance, CL has been used to measure mechanical forces applied to polymers.1 In this study, we have investigated CL reactions in molecular crystals, to create the chemistry of “soft crystals”2 as reaction fields. For this purpose, we investigated CL properties of adamantylideneadamantane 1,2-dioxetanes (Adox) conjugated with a fluorophore in the crystalline state. We report here characteristic CL properties of the Adox derivatives and talk about the molecular mechanism of the crystalline-state CL.3 Adox is one of stable 1,2-dioxetanes, and its thermal decomposition partially gives the excited singlet (S1) or triplet (T1) state of 2-adamantanone (AdCO).4 The S1 state of AdCO can fluoresce weakly with the maximum at 420 nm. A designed Adox derivative 1 has a non-π-conjugatively linked phthahlimide as a crystal structure modulator and the emitting moiety by accepting energy from the excited AdCO. We first prepared syn- and anti-isomers of the Adox derivative 1 and investigated their CL properties in crystals. The isomers showed contrastive CL properties by heating their crystal samples at 160 °C. Each crystal structure of the isomers has its own distinctive packing pattern of the Adox and phthalimide moieties, and the clear differences in CL intensities, emission maxima and reaction kinetics of the isomers are well correlated to the packing patterns. Thus, CL emission properties and reaction kinetics in the crystalline-state were precisely manipulated by the crystal structures. To understand the crystalline-state CL reactions in detail, we further investigated CL of modified Adox derivatives along with thermoanalytical studies. The results provide information on the origins of the characteristic CL behaviors and the reaction mechanism in soft crystals.1) Chen, Y.; Spiering, A. J. H.; Karthikeyan, S.; Peters, G. W. M.; Meijer, E. W.; Sijbesma, R. P., Nat. Chem., 2012, 4, 559.2) Kato, M.; Ito, H.; Hasegawa, M.; Ishii, K., Chem. Eur. J., 2019, 25, 5105.3) Matsuhashi, C.; Ueno, T.; Uekusa, H.; Sato-Tomita, A.; Ichiyanagi, K.; Maki, S.; Hirano, T., Chem. Commun., 2020, 56, 3369.4) Hummelen, J. C.; Luider, T. M.; Wynberg, H., Pure Appl. Chem., 1987, 59, 639. Figure 1

Enhancement of ethylene-air continuous rotating detonation in the cavity-based annular combustor

To investigate enhancement effects of cavity on continuous rotating detonation (CRD), extensive ethylene-air CRD tests are conducted in the cavity-based annular combustor. By varying the length-to-depth ratio (L/D) of cavity, five modes are distinguished and classified into three operating zones, I: Excessive Impact (deflagration and sawtooth wave); II: Proper Impact (single wave and co-rotating two-wave); III: Deficient Impact (counter-rotating two-wave). In the cavities with small L/D in zone I, excessive deflagration could inhibit the accumulation of combustible mixture, making detonation degenerate into deflagration. While the cavities with proper L/D in zone II could intensify CRD, resulting in a propagation mode transformation from counter-rotating two-wave to co-rotating mode. The added circumferential contact surface between the cavity-stabilized flame and combustible mixture is a key factor of cavity enhancement, which can pre-heat combustible mixture and reduce the detonation inducing time. Through the distribution of chemiluminescence intensity ratio, the intensity ratio peaks of deflagration and detonation are estimated to be in 40-50 mm and 20-30 mm downstream from the inlet respectively, indicating that detonation with proper cavities is accomplished in shorter distance. Overall, L/D=5.5 with the depth of 20 mm may be an optimized selection based on the evaluations of mode, reaction zone, and pressure.

A new enhanced chemiluminescence reaction based on polymer dots for the determination of metronidazole

Polymer dots (PDs) with non-conjugated functional groups are attracting nanomaterials due to their ease of synthesis, the biocompatibility of precursors, and low toxicity. In this work, PDs with non-conjugated groups were synthesized with a simple and straightforward method by Schiff base reaction. Then their possible application in the chemiluminescence (CL) reactions was explored. Results were shown that PDs increased the CL intensity of the NaIO4-fluorescein system about 15 times. Regarding the CL mechanism, we proved that the emitting species is fluorescein, which can be excited by the energy transfer from the excited-state PDs. It was observed that CL emission is promoted by the interaction of metronidazole (MND) with the PDs. Therefore, we designed a novel and sensitive assay for MND based on its enhancing effect on NaIO4-fluorescein-PDs CL system. The introduced assay showed a linear response in the range of 5.0–300 nM with a detection limit of 1.5 nM. The method was used for the determination of MND in spiked plasma samples.

Computational and experimental investigation of ignition in a Mach 2 cavity-based flameholder

The ignition and flame propagation in an ethylene fueled Mach 2 supersonic cavity are investigated experimentally and computationally. A laser spark is placed in the base of the cavity and the combustion process is tracked using broadband chemiluminescence. Computationally, hybrid Reynolds-averaged Navier-Stokes/large eddy simulation combined with a 22 species chemistry mechanism is used to simulate the ignition process. The simulation is used to explain the underlying physics and flow features leading to the chemiluminescence intensity profile observed experimentally. Initially, the flame kernel spreads in the spanwise direction to fill the region near the cavity's aft-facing step before moving axially downstream to ignite the entire cavity. The flame causes an increase in pressure, restricting fuel flow from the injectors, subsequently leading to leaner conditions that reduce overall heat release. Heat release reduction lowers the pressure and allows the fuel to flow back into the cavity as the flame adjusts to its steady state configuration. At steady state, the elemental fuel concentration within the cavity is significantly higher compared to the non-reacting condition. Examining the ignition time-scales, it is found that the increase in elemental fuel concentration lags approximately 2 milliseconds behind the increase in pressure as the recirculation and diffusion in the cavity transports the additional fuel into the domain. In addition to the full-width simulation, a partial-width simulation that is 1/6 the size of the experimental domain with periodic boundaries is evaluated as a potential cost-saving option. Due to the decreased domain size, the time scales related to ignition were shortened versus the full-width simulation which showed consistent time scales with the experimental findings. The partial-width simulation, however, was able to capture the major stages of combustion during the ignition process.

Intensity of free-radical reactions in metastasizing cervical cancer.

e17508 Background: Cervical cancer (CC) is one of the main causes of death among patients with gynecological tumors. As a rule, patients die from relapses and metastases which rates reach 30-45%. According to research data, treatment of patients with distant metastases is ineffective, and half of them die within 9.7 months, while the average survival is 15.9±0.26 months. The development of many pathological processes is considered to be associated with an increase in free-radical reactions leading to oxidative damage to various biomolecules. The purpose of the study was to analyze some characteristics of the free-radical oxidation and antioxidant defence in metastasizing CC. Methods: The study included 56 patients aged 29-73 years with stage IIB-IV CC after antitumor treatment. The main group – 27 patients who developed metastases within 4 months to 8 years after the CC diagnosis; controls – 29 patients with non-metastatic CC; donors – 19 healthy women aged 27-61 years. The accumulation of carbonyl derivatives in blood plasma proteins was detected in the reaction with 2, 4-dinitrophenylhydrazine. The induced oxidative modification of proteins was stimulated with Fenton's reagent. Free-radical processes was evaluated by the intensity of peroxide-induced luminol-dependent plasma chemiluminescence and the content of nitric oxide metabolites; the intensity of lipid peroxidation - by the content of malondialdehyde (MDA); the activity of catalase and ceruloplasmin was also studied. Results: CC progression was accompanied by increasing lipid peroxidation and spontaneous oxidation of blood plasma proteins. MDA levels in patients with metastases increased by 57.8% compared to donors and by 34.3% compared to patients without metastases (p < 0.05). The concentration of 2, 4-dinitrophenylhydrozones increased on average by 4 times compared to donors and by almost 2 times compared to patients without metastases. Patients with metastasizing CC demonstrated elevated levels of products of the interaction of nitric oxide and its derivatives with proteins and peptides - 3-nitrotyrosine and nitrosoglutathione, compared to both donors (by 31.4% and 55.3%) and patients in remission (by 38.1% and 34.5%). Chemiluminescence activity increased by 54.5% compared to donors (p < 0.05) and by 93% (p < 0.01) compared to controls. Catalase activity in the blood plasma of patients with metastases increased by 54.1% compared to donors, but was lower than the values in the control group (by 22.1%). Ceruloplasmin activity was increased only in patients without metastases (by 33%). Conclusions: The process of CC metastasis is accompanied by a greater intensity of oxidative processes of both proteins and lipids, as well as depletion of the adaptive capabilities of the body's antioxidant system.

In-situ generation of potassium ferricyanide for label-free and enzyme-free chemiluminescence detection of telomerase activity

Chemiluminescence (CL) assay is a promising point-of-care testing (POCT) technology due to the fast response, high sensitivity, and easy miniaturization. The application and performance of CL POCT method were highly dependent on the CL reaction. Herein, based on the CL reaction between luminol and in-situ generated K3Fe(CN)6, a low-cost, enzyme-free, and label-free CL POCT method was explored via a portable and handheld luminometer to detect telomerase activity. Telomerase elongated telomere substrate (TS) primer to form (TTAGGG)n repeats which hybridize with multiple short DNAs. The intercalation of SYBR Green I (SGI) into double-stranded DNA (dsDNA) generated singlet oxygen under the irradiation of LED light source. Singlet oxygen was then employed for in-situ oxidation of K4Fe(CN)6 to K3Fe(CN)6, which could react with luminol to generate a strong CL intensity. Thus, telomerase activity could be specifically, sensitively, and label-free detected. The detection limit was down to 98 HeLa cells. The detection process was very simple, and the cost was about $0.01 for each measurement. Furthermore, telomerase activity was detectable in human serum samples, with spike recoveries from 96% to 105%. According to our knowledge, it is the first effort to develop a low-cost, label-free and enzyme-free CL method with good repeatability for detecting biomarker based on the analyte-triggered and in-situ generated K3Fe(CN)6/luminol CL reaction.

Metal enhanced chemiluminescence nanosensor for ultrasensitive bioassay based on silver nanoparticles modified functional DNA dendrimer

A novel metal enhanced chemiluminescence (MEC) nanosensor was developed for ultrasensitive biosensing and imaging, based on functional DNA dendrimer (FDD), proximity-dependent DNAzyme and silver nanoparticles (AgNPs). The FDD containing two split G-quadruplex structures was prepared through an enzyme-free and step-by-step assembly strategy, and then reacted with AgNPs and hemin molecules to form the FDD/hemin/AgNPs facilely. Such a MEC nanosensor consisted of three modules: FDD (scaffold), the generated G-quadruplex/hemin DNAzyme (signal reporter) and AgNPs (chemiluminescence enhancer). The MEC effect was achieved by controlling the length of DNA sequences between AgNPs on the periphery of FDD and DNAzymes inside it. Such nanosensor exhibited 9-fold amplification and another 6.4-fold metal enhancement in chemiluminescence intensity, which can be easily applied into trace detection of multiple protein markers using a disposable protein immunoarray. The FDD/hemin/AgNPs-based multiplex MEC imaging assay showed wide linear ranges over 5 orders of magnitude and detection limits down to 5× 10−5 ng L−1 and 1.8 × 10−4 U mL−1 for cardiac troponin T and carcinoma antigen 125, demonstrating a promising potential in application to protein analysis and clinical diagnosis. Moreover, the MEC nanosensor can be effectively delivered into cells with excellent biocompatibility and outstanding stability, offering a new tool for detection of intracellular targets and suggesting wide applications in bioassay.

Experimental investigation of equivalence ratio fluctuations in a lean premixed kerosene combustor

In this study a measurement technique for determination of equivalence ratio fluctuations from flame chemiluminescence in a kerosene-fuelled lean premixed combustor under atmospheric conditions is presented. Firstly, fundamental investigations into the relationship between the ratio of different chemiluminescence signals and the equivalence ratio are carried out using an imaging spectrometer. The chemiluminescence intensity is recorded for a wide range of equivalence ratios and fuel mass flows during steady state operation. The spectra show that the CH*/OH* ratio depends linearly on the equivalence ratio and is independent of the mass flow in the investigated range. Moreover, the background radiation has no influence on the monotonous trend of the CH*/OH* ratio for kerosene combustion. This interesting finding opens up new possibilities for passive optical measurement of the equivalence ratio in kerosene flames. Bandpass-filtered phase-correlated images of OH* and CH* chemiluminescence of an acoustically excited flame are taken simultaneously on one camera chip using an image doubler. After distortion correction, the image pair is used to calculate the global equivalence ratio from the CH*/OH* ratio. Based on the calibration chart derived in stationary operation, phase-resolved equivalence ratio perturbations are determined during acoustic excitation. The presented technique allows a quantitative measurement of equivalence ratio fluctuations in spray combustion and can therefore provide a better understanding of the fundamental mechanisms of thermoacoustic instabilities triggered by equivalence ratio fluctuations.Graphic abstract

Reconstruction model for heat release rate based on artificial neural network

Optimizing the distribution of heat release rate (HRR) is the key to improve the performance of various combustors. However, limited by current diagnostic techniques, the spatial measurement of HRR in many realistic combustion devices is often difficult or even impossible. HRR prediction is theoretically possible through establishing correlations between HRR and other quantities (e.g., chemiluminescence intensity) that can be experimentally determined; however, up to now, few universal correlations have been established. A novel artificial neural network (ANN) approach was adopted to build the mapping relationship between the combustion heat release rate and the measurable chemiluminescent species. Proper orthogonal decomposition (POD) technology is used to extract the combustion physics and reduce the data of the spatial-temporally high-resolution combustion field. The correlation between the reduced-order HRR and chemiluminescent species is built using an ANN model. A unique segmentation approach was proposed to improve the training efficiency and accuracy. Validation in a supersonic hydrogen-oxygen nonpremixed flame proves the accuracy and efficiency of the proposed HRR reconstruction model based on the reduced-order POD method and data-driven ANN model.

Chemiluminescence studies on the photooxidation of isotactic polypropylene

Photooxidation of polypropylene (PP) was investigated by chemiluminescence (CL) after UV irradiation of main wavelengths of 254 nm and 365 nm in air at an ambient temperature. From the kinetic analysis of CL intensity change just after irradiation, CL intensity at the time of the cessation of UV irradiation, (I(t=0)), was obtained. The irradiation time dependence of I(t=0) gave a time-course, where the CL intensity increased with time in the first stage and reached a steady state, and after maintaining the same level for a while, it largely increased in the later stage. The steady state intensity, which is considered the rate of peroxy radical formation, was found to be dependent on the crystallinity of PP. The lower the crystallinity is, the higher the steady state intensity is, indicating the preferential photoinitiation reaction to occur in the amorphous phase. The isothermal CL measurement at above the melting point of the samples, which were stored at 25 °C for various periods after UV irradiation, suggests that there are two types of CL emitting sources of different lifetimes; one is quenched in about one day and the other survives for more than 10 days. The temperature rising measurement also indicates the existence of two types of CL emitting sources, too. Further, thermal oxidation before UV irradiation was found to clearly promote the photooxidation. In contrast, thermal oxidation in oxygen was increasingly accelerated by the pre-photooxidation.

A novel metal organic gel with superior oxidase-like activity for efficient and sensitive chemiluminescence detection of uric acid

It is found that MIL-100(Fe) gels, as a kind of metal-organic gels (MOGs), constitutting of iron (Fe3+) and trimesic acid (H3BTC), has been regarded as the efficient catalyst of luminol chemiluminescence (CL) system without the presence of extra oxidants in the present work. MIL-100(Fe) gels that have possessed mimicking oxidase-like activity can excellently enhanced luminol CL intensity by accelerating the generation of reactive oxygen species. Furthermore, with the addition of uric acid (UA), the CL signal has been dramatically inhibited under alkaline condition. Hence, the CL intensity inhibiting ratio (I0/IS) was proportional to the increasing concentration of UA in the rang from 10 nM to 4000 nM with the detection limit of 5.9 nM. This method has been successfully applied for analysis of UA with acceptable recoveries ranging from 97.0% to 107.9% in urine sample. These results indicates that this study open up a novel, sensitive and convenient method to detect UA in biological samples.

Chemiluminescence Sensor Based on Composite Functional Nucleic Acid for Detection of Ochratoxin A in Wine

A chemiluminescence (CL) sensor, using ochratoxin A (OTA) aptamer as the activation switch of the split DNAzyme, was established to achieve high-sensitivity detection of OTA in wine. A guanine-rich oligonucleotide can fold into a parallel G-quadruplex in K + solution. Hemin as a ligand can bind to parallel G-quadruplexes precisely. Hemin-G-quadruplex complexes display peroxidase-like activity, named as DNAzyme. The activity of the DNAzyme can be measured by CL via the H 2 O 2 mediated-oxidation with luminol. Guanine-rich oligonucleotide split into two fragments; when they were near each other, they could reform DNAzyme. OTA aptamer as a switch was inserted into the nucleic acid sequence of DNAzyme. In the absence of OTA, the unfolded OTA aptamer inhibited the split DNAzyme effective self-assemble to form a structure with enzymatic activity. In the presence of OTA, OTA induced the aptamer to form an antiparallel G-quadruplex and drew the tail of the aptamer closer so that the two fragments of split DNAzyme refolded and compound with hemin. The folding degree of the aptamer would directly affect the activity of DNAzyme and high-sensitivity detection of OTA could be obtained by monitoring the enhanced ratio of CL intensity. The linear range of this method was 0.10–2.00 nmol/L, and the limit of detection was 0.10 nmol/L. OTA aptamer as a switch is inserted into the nucleic acid sequence of DNAzyme. OTA induces the aptamer to form an antiparallel G-quadruplex and draws the split DNAzyme refold and compound with hemin. The folding degree of the aptamer will directly affect the activity of DNAzyme and high-sensitivity detection of OTA can be obtained by monitoring the enhanced ratio of chemiluminescence intensity.

Self-organized plasmonic metasurfaces: The role of the Purcell effect in metal-enhanced chemiluminescence (MEC)

Chemiluminophores are entities, which exhibit wide-band light emission without any external light source, just caused by a chemical reaction. Since chemiluminescence usually yields to unfavorable competition with other channels of chemical energy dissipation, plasmonic nanoparticles can be employed to enhance the chemiluminescence quantum yield via acceleration of the radiative decay rate due to the Purcell effect. On the other hand, the catalytic action of metallic surface can contribute to the chemical reaction rate. Both mechanisms can lead to substantial chemiluminescence intensity enhancement when chemiluminophores are in contact with metal nanoparticles. Although the investigations devoted to MEC are numerous, the relative roles of the Purcell effect and catalysis in the chemiluminescence enhancement are still unclear. In this paper, with the use of a thin inert spacer layer deposited on top of a silver metasurface, we observe a moderate decrease of the chemiluminescence enhancement, which favors an electrodynamic mechanism. We also check that the continuous silver film without plasmon resonances causes no measurable chemiluminescence enhancement. As the results supported the electrodynamic mechanism of MEC, silver nanoparticles with suitable properties have been fabricated via physical vapor deposition on the substrate. We have theoretically optimized the silver nanoparticles shape and size distributions to tune their localized surface plasmon bands for the best overlap with the emission of luminol and some other chemiluminophores. Our design for plasmonic nanoparticles placed on the dielectric material may motivate a new generation of chemiluminescence-based devices for sensing applications.

Cobalt-imidazole metal-organic framework loaded with luminol for paper-based chemiluminescence detection of catechol with use of a smartphone.

Chemiluminescence (CL) reagent luminol was loaded into the porous structure of cobalt-imidazole metal-organic framework (MOF) ZIF-67 to obtain luminol-functionalized ZIF-67 (luminol@ZIF-67) with CL property. The morphology, composition, CL property, and CL mechanism of luminol@ZIF-67 were carefully investigated. The obtained luminol@ZIF-67 exhibited strong, stable, and visible CL emission that reacted with H2O2, attributed to the strong catalytic effect of ZIF-67 combined with the shortened diffusion distance between luminol and the catalytic center. The CL intensity of luminol@ZIF-67 was more than 550 times higher than that of luminol. Catechol can effectively quench the CL emission of luminol@ZIF-67 that reacted with H2O2. Then, a simple paper-based CL imaging detection method was developed for the detection of catechol by using a smartphone as a portable detector. The linear calibration curve of the developed CL assay for catechol ranged from 5 to 100mg/L with detection limit of 1.1mg/L (S/N = 3δ). The strong CL emission of luminol@ZIF-67 combined with the effective quench ability of catechol guaranteed high sensitivity of the detection method. The practical application ability of the developed CL assay was tested by the determination of catechol in tea and tap water samples, resulting in acceptable results. This work provides an effective paper-based CL detection method for catechol and enriches the species of the chemiluminescent MOF material.

Integration of 3D Hydrodynamic Focused Microreactor with Microfluidic Chemiluminescence Sensing for Online Synthesis and Catalytical Characterization of Gold Nanoparticles.

Chemiluminescence assays have shown great advantages compared with other optical techniques. Gold nanoparticles have drawn much attention in chemiluminescence analysis systems as an enzyme-free catalyst. The catalytic activity of gold nanoparticles for chemiluminescence sensing depends on size, shape and the surface charge property, which is hard to characterize in batches. As there is no positive or negative correlation between chemiluminescence signals and sizes of gold nanoparticles, the best way to get optimal gold nanoparticles is to control the reaction conditions via online chemiluminescence sensing systems. Therefore, a new method was developed for online synthesis of gold nanoparticles with a three-dimension hydrodynamic focusing microreactor, directly coupled with a microfluidic chemiluminescence sensing chip, which was coupled to a charge-coupled device camera for direct catalytical characterization of gold nanoparticles. All operations were performed in an automatic way with a program controlled by Matlab. Gold nanoparticles were synthesized through a single-phase reaction using glucose as a reducing agent and stabilizer at room temperature. The property of gold nanoparticles was easily controlled with the three-dimension microreactor during synthesis. The catalyst property of synthesized gold nanoparticles was characterized in a luminol–NaOCl chemiluminescence system. After optimizing parameters of synthesis, the chemiluminescence signal was enhanced to a factor of 171. The gold nanoparticles synthesized under optimal conditions for the luminol–NaOCl system were stable for at least one month. To further investigate the catalytic activity of synthesized gold nanoparticles in various situations, two methods were used to change the property of gold nanoparticles. After adding a certain amount of salt (NaCl), gold nanoparticles aggregated with a changed surface charge property and the catalytic activity was greatly enhanced. Glutathione was used as an example of molecules with thiol groups which interact with gold nanoparticles and reduce the catalytic activity. The chemiluminescence intensity was reduced by 98.9%. Therefore, we could show that using a microreactor for gold nanoparticles synthesis and direct coupling with microfluidic chemiluminescence sensing offers a promising monitoring method to find the best synthesis condition of gold nanoparticles for catalytic activity.

Emissions Performance of Staged Premixed and Diffusion Combustor Concepts for an NH3/Air Flame With and Without Reactant Humidification

Abstract Renewably generated ammonia offers a form of carbon-free chemical energy storage to meet the differences between uncertain supply and fluctuating demand and has the potential to support future energy requirements. The storage/transportation characteristics of NH3 are favorable compared with H2; however, there are combustion research challenges to enhance fuel reactivity while reducing harmful emissions production. The purpose of this work was to evaluate different fuel delivery concepts for a representative gas turbine combustor. An experimental and numerical comparison was made between swirl-stabilized premixed and diffusion NH3–air flames at elevated inlet temperature (473 K). The exhaust NOx and NH3 emissions generated from each concept were quantified to optimize combustor performance. High-speed OH* and NH2* chemiluminescence was employed to characterize the change in flame topology with variation in fuel–air equivalence ratio, and the resultant influence on measured emission concentrations. Chemiluminescence intensities were shown to elucidate changes in sampled exhaust emissions, enabling detailed analysis of intermediate chemistry. A comparison was made between experimental data and kinetic simulations, demonstrating the sensitivity of NOx emissions to premixed fuel–air equivalence ratio. A comparison was also made between exclusive primary airflow, and the staged introduction of secondary air, to quantify the change in NOx production between each configuration and improve fuel burnout. Secondary air loadings were incrementally increased through the combustor. Finally, reactant humidification was employed as a secondary process for NOx reduction, having shown favorable performance with NH3–H2 mixtures, with the efficacy compared for both premixed and diffusion configurations.

Enrichment of deoxynivalenol and establishment of online early warning treatment system for drinking water

AbstractAn online monitoring and early warning system was established to detect drinking water pollution from deoxynivalenol (DON). Flow injection chemiluminescence was selected as online monitoring tool for its low detection limit, fast detection process and broad linear range. The toxigenic strain of Fusarium graminearum (GDMCC3.507, freeze‐dried powder) was incubated and grown on potato dextrose agar (PDA) culture medium under constant temperature of 26 °C for 5 days. Different culture conditions were investigated to determine the most suitable conditions to culture the fungi and enrich DON that produced by Fusarium graminearum. Powder activated carbon (PAC) was used to remove DON in drinking water. A dynamic threshold X ± 5SD was established to detect DON in drinking water effectively. Calculation of standard curve indicated that 6 mg DON could be easily extracted from 100 mg corn culture medium. Emergency detoxification was achieved by PAC and the removal rate reached 76% after 50 min of adsorption process. Once the chemiluminescence intensity exceeded the X ± 5SD value of the exact point during the monitoring process, the tap water was estimated to have excessive toxin. The establishment of this emergency system could provide a basis for dealing with sudden pollution of drinking water.