Fluorescence Analysis Method Research Articles

Analysis to Mullite Bonded Corundum Purging Plug

We chose a purging plug with good performance to analyze its insert plate. By X ray fluorescence analysis method, the main chemical composition is alumina and the small amount is silica. XRD analysis shows its phase compositions, main crystal phase is corundum, the secondary phase is mullite. SEM analysis is for the microstructure, grains are packed closely. They are sintered tabular corundums with smooth shape, which means there is liquid phase in sintering process to help mass transfer. As a conclusion, this product is designed from the point of material selection and structure control to improve its thermal shock resistance. Compacted microstructure combining with good thermal shock-resistance mineral phases improve the service life of purging plug.

Development of a fluorescence analysis method for N-acetylneuraminic acid and its oxidized product ADOA

N-acetylneuraminic acid (NANA) consumes toxic hydrogen peroxide (H2O2) under physiological conditions and is oxidized by an equimolar amount of H2O2 to yield its decarboxylated product 4-(acetylamino)-2,4-dideoxy-d-glycero-d-galacto-octonic acid (ADOA). Highly sensitive analytical methods are required to detect ADOA in the human body. We labeled NANA and ADOA with 4-(N,N-dimethylaminosulfonyl)-7-(2-aminoethylamino)-2,1,3-benzoxadiazole (DBD-ED) to enable their fluorometric detection, and developed a method using HPLC with fluorometric detection (HPLC-FD) for the simultaneous determination of the derivatized NANA and ADOA. The derivatized NANA and ADOA were separated by a hydrophilic interaction liquid chromatography (HILIC) column using an H2O/CH3CN/HCOOH (10/90/0.35) mobile phase. Fluorescence was monitored at excitation and emission wavelengths of 450nm and 560nm, respectively. Both intra- and inter-day (n=6) repeat determinations of the DBD-ED-derivatized NANA and ADOA gave relative standard deviations of less than 5%. The calibration curves for standard solutions of DBD-ED-derivatized NANA and ADOA were linear over the ranges from 576fmol to 2.0nmol and 556fmol to 2.0nmol, respectively. The method developed was highly specific and sensitive for NANA and ADOA. The presence of ADOA in biological samples was revealed for the first time using this method.

SINTESIS KATALIS CuO-ZEOLIT ALAM UNTUK REAKSI REDUKSI GAS NO2 MENGGUNAKAN REDUKTOR SENYAWA HIDROKARBON

The exhaust gases from automobile engines and industrial boilers contain mainly oxides of carbon (CO and CO2), oxides of nitrogen (NOx), hydrocarbons (HC), sulphur dioxide (SO2), particulates and soot. One of the most urgent problems is removal of NOx, typically produced during high-temperature combustion and contribute to formation of smog and ground-level ozone by reacting with hydrocarbons in presence of sunlight. Preparation, and modification of CuO / natural zeolite as well as their characterizations had been carried out. The aim of this research is to prepare the best characters catalyst for selective catalytic reduction of NOx. The CuO / natural zeolite was prepared by mechanically mixing of 100 g of natural zeolite, which it has been heated at 400oC, with CuNO3.3H2O powder, The weight ratio of the mixture was 2.5 and 5% (w/w). The mixture was then calcined at 400oC for 6 hours. The calcined product was characterized using X-Ray Diffractometry, X-Ray Fluorescence analysis and Gas Sorption Analysis methods to determine its physicochemical properties changes caused by mixing and calcination. The characterization results showed that dispertion of CuNO3.3H2O on zeolite resulted in the increasing of copper concentration on CuO / natural zeolite. The concentration of Cu on natural zeolite was found to be 0.15% (w/w), meanwhile on CuO / natural zeolite was 2.29% (w/w). From X-Ray Diffractometry analysis result no information was found that CuO was dipersed on natural zeolite. It was caused by overlapping of the reflections of zeolite with reflections of CuO. On the otherhand, the gas sorption analysis result exhibited that the dispersion of CuO on zeolite resulted in the decreasing of total pore volume as well as specific surface area of the natural zeolite. The specific surface areas of natural zeolite and CuO / natural zeolite were 228,1 and 172,1 m2/g, respectively, meanwhile the total pore volumes of natural zeolite and CuO / natural zeolite were 0.2316 and 0.2108 m3/g

Application of the X-ray fluorescence analysis and X-ray diffraction in geochemical studies of the Pleistocene tills from Holy Cross Mountains

X-ray fluorescence analysis methods (wavelength dispersive X-ray fluorescence analysis (WDXRF) and total reflection X-ray fluorescence (TXRF)) and X-ray powder diffraction (XRPD) have been applied in complementary geochemical studies of the Pleistocene till samples. The XRPD technique gave information about the mineral composition of the analyzed samples while the WDXRF and TXRF studies allowed the fast elemental analysis. The till samples were collected from different regions of Holy Cross Mountains (located in central Poland) which are still not unambiguously described in the context of the geochemical studies of the Quaternary sediments. The analysis was concentrated on the geochemical composition of the till samples both for materials occurring on the surface (characterized by continuous weathering processes) and for samples taken from core borehole. The overriding purpose of these studies is determination of the local lithotype of the tills and its lithologic and petrographic diagnostic properties, including the chemical composition of clay and minerals found in the clay. In the presented work the experimental sets up, sample preparation procedure and measurements programme will be discussed in details. Finally, the elemental and mineral compositions will be presented for studied different groups of the samples.

Study on Detection and Classification of Tetracycline Residue in Duck Meat Using Synchronous Fluorescence Spectra and Support Vector Machine

To the rapid detection of whether the tetracycline residues are excess in duck meat, the optimum characteristic wavelength difference λ was determined by synchronous fluorescence analytical method. The recognition model of different residual levels of tetracycline was established by using support vector machine classification algorithm. Firstly, the optimum wavelength difference λ for duck meat samples was determined as 70nm, and synchronous fluorescence spectra of different samples under the condition of λ 70nm were collected. Secondly, original synchronous fluorescence spectra were preprocessed by using standard normal variables change (SNV). Finally, 18 wavelength variables were selected from 121 wavelength variables of pretreatment spectra by using competitive adaptive reweighted sampling (CARS). Then the radial basis function (RBF) was selected as the kernel function of support vector classification (SVC), and the optimal kernel function factor C and g were determined as 2.83 and 1, respectively, which were obtained by using grid searching combined with 5-fold cross validation. The classification model of SNV-CARS-SVC was established, and the classification accuracy rate of the model was 95.7% for prediction sets samples. The results showed that the synchronous fluorescence analysis method could identify tetracycline different residual levels quickly and accurately, and a feasible method was provided for identifying the quality of duck meat.

Protein–DNA force assay in a microfluidic format

The detailed study of protein-DNA interactions is a core effort to elucidate physiological processes, including gene regulation, DNA repair and the immune response. The molecular force assay (MFA) is an established method to study DNA-binding proteins. In particular, high-affinity binder dissociation is made possible by the application of force. Microfluidic lab-on-a-chip approaches have proven helpful for parallelization, small sample volumes, reproducibility, and low cost. We report the successful combination of these two principles, forming a microfluidic molecular force assay and representing a novel use for the established MITOMI chip design. We present, characterize, validate and apply this integrated method. An alternative confocal fluorescence microscopy readout and analysis method is introduced and validated. In a multiplexing application, EcoRI binding is detected and characterized. This method paves the way for quantitative on-chip force measurements. It is suited for integration with DNA micro-spotting and in vitro expression of transcription factors to form a high-throughput chip for detailed DNA-protein interaction studies.

Assessment of Lead, Zirconium and Iron Concentration in Soils in Parts of Jos Plateau, North Central Nigeria

Thirty soil samples from Rayfield, Bukuru and environs on the Jos Plateau were analysed for lead (Pb), Zirconium (Zr) and Iron(Fe) using the X-ray fluorescence (XRF) analytical method, with the aim of determining the extent to which the long history of mining, and other suficial processes have affected the soils of the study area. The distribution of the analysed elements (Pb, Zr, Fe) were evaluated to monitor potential threats to human health and the natural ecosystem by comparing the determined concentrations of these elements (Pb, Zr, Fe) with concentrations in uncultivated and unmined areas as controls.Mean concen- trations of 223.67ppm was obtained for Pb; 425.53ppm for Zr and 56208.7ppm for Fe as against 17ppm, 270ppm and 21000ppm for Pb, Zr, and Fe respectively inunmined and uncultivated soils.A calculation of anthropogenic factor (AF) and Index of geo-accumulation (Igeo) indicated Pb, Zr and Fe contaminations (Pb moderate to high, Zr and Fe low to moderate contamina- tions) in soils of the study area. These values can be used as guidelines for ensuring the preservation of environmental integrity of the study area.

Effects of Chinese herbal monomers on oxidative phosphorylation and membrane potential in cerebral mitochondria isolated from hypoxia-exposed rats in vitro.

Mitochondrial dysfunction is the key pathogenic mechanism of cerebral injury induced by high-altitude hypoxia. Some Chinese herbal monomers may exert anti-hypoxic effects through enhancing the efficiency of oxidative phosphorylation. In this study, effects of 10 kinds of Chinese herbal monomers on mitochondrial respiration and membrane potential of cerebral mitochondria isolated from hypoxia-exposed rats in vitro were investigated to screen anti-hypoxic drugs. Rats were exposed to a low-pressure environment of 405.35 mm Hg (54.04 kPa) for 3 days to establish high-altitude hypoxic models. Cerebral mitochondria were isolated and treated with different concentrations of Chinese herbal monomers (sinomenine, silymarin, glycyrrhizic acid, baicalin, quercetin, ginkgolide B, saffron, piperine, ginsenoside Rg1 and oxymatrine) for 5 minutes in vitro. Mitochondrial oxygen consumption and membrane potential were measured using a Clark oxygen electrode and the rhodamine 123 fluorescence analysis method, respectively. Hypoxic exposure significantly decreased the state 3 respiratory rate, respiratory control rate and mitochondrial membrane potential, and significantly increased the state 4 respiratory rate. Treatment with saffron, ginsenoside Rg1 and oxymatrine increased the respiratory control rate in cerebral mitochondria isolated from hypoxia-exposed rats in dose-dependent manners in vitro, while ginsenoside Rg1, piperine and oxymatrine significantly increased the mitochondrial membrane potential in cerebral mitochondria from hypoxia-exposed rats. The Chinese herbal monomers saffron, ginsenoside Rg1, piperine and oxymatrine could thus improve cerebral mitochondrial disorders in oxidative phosphorylation induced by hypobaric hypoxia exposure in vitro.

Study on Enzymatic Hydrolysis into Low Molecular Weight Polypeptides with Microwave Heating

Using amino nitrogen content ( AN for short ) as standards, the conditions of low molecular weight polypeptides with three kinds of enzymes hydrolysis as well as the sequence and way of adding enzymes with microwave heating was found in this paper, which was examined by fluorescence analysis method, seperated by Sephadex G-50. The result shows that three kinds of enzymes hydrolysis were prefer to one enzyme obviously, amino nitrogen was higher for 2813.4 mg/L, the relative molecular mass of soybean polypeptides was mostly below 1000 D. Soybean polypeptide was well tested and seperated by Sephadex G-50 and fluorescence analysis method.

LASER FLUORESCENCE ANALYSIS METHOD USE FOR EXPRESS-DIAGNOSIS OF ANTIBIOTIC RESISTANCE AMONG ABDOMINAL SEPSIS PATIENTS POST-OPERATION

The adequate method of antibiotic choice is reported using the laser fluorescence analysis of blood plasma with the laboratory diagnostic device "Spectrolux-MB". The method is based on the ability of micro-organisms and products of their vital functions (metabolism) to fluoresce under laser radiation. The method of fluorescence analysis has great prospects in urgent surgery and other medicine brunches due to its high information content, low cost (compared to other methods of express-diagnostics) and high speed of information acquisition.

Determination of PAHs in River Water Using Bamboo Charcoal as a Solid-Phase Extraction Adsorbent by Synchronous Fluorescence Spectrometry

A solid-phase extraction (SPE) using bamboo charcoal as absorbent coupled with constant wavelength synchronous fluorescence (CWSL) analytical method was developed for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. A new method for simultaneous determination for sixteen kinds of polycyclic aromatic hydrocarbons (PAHs) in water was developed by constant wavelength synchronous fluorescence (CWSL) with bamboo charcoal solid phase extraction. The four main factors influencing on extraction efficiency, that is, type and volume of the elution solvent, sampling speed and volume were investigated. A solid-phase extraction with bamboo charcoal cartridges was carried out and the elution was performed with 15 mL of n-hexane. Sampling speed was 5 mL/min. Sampling volume was 500 mL. The linear response of this method was in the range of 0~1000ng/mL (r ≥ 0.9988), the relative standard deviations (RSDs) were in the range of 0.017%~4.12% (n = 6). The detection limits were in the range of 0.052~12.37ng /mL. .By using this method, real samples were determined directly and good results were obtained with the recoveries of 78.87%-107.9%in water from the Longjin river estuary of the provincial control section. The results showed the method was cheap, simple, and could used as an excellent alternative for the routine analysis in environmental field.

Chlorophyll fluorescence of soybeans under the condition of drought generation

We used the Chlorophyll fluorescence analysis method to study Chlorophyll of soybeans under the condition of drought generation. The result showed that the drought generation at the stage of blossom made the Fo of many researched soybean varieties increase. However, there was not any clear change in the variable fluorescence efficiency of almost strains. Particularly, the Fvm of DT12 decreased when lacking water. At the stage of tender nuts, the Fo of many strains was lower than that at the stage of blossom; however, this value in the experimental plot was higher than the comparative one and Fvm were equivalent in the two plots. Meanwhile, the Fvm of DT12 in the drought-generated plot was still clearly lower than in the comparative plot, which proved that this variety had not recovered its fluorescence ability after being generated drought. When being watered again, Fo of soybeans tended to reduce, Fm fluctuated wildly, not followed a certain direction and Fvm of almost strains tended to grow. The strains DT84 and AK06 are fairly good drought-resistant ones as they had quite stable fluorescence indexes in the drought generation and in the process of watering again after being withered.

Novel Fiber Optic Detection Method for in Situ Analysis of Fluorescently Labeled Biosensor Organisms

This research presents a novel, time-resolved fiber-optic "Optrode" system for accurate real-time in situ detection of fluorescent proteins produced by biosensor organisms. The Optrode fluorescence detection system was able to identify, characterize, differentiate, and quantify red and green fluorescently labeled organisms, individually and in mixed aqueous cultures. Detection was also possible in sand systems, where a consistent reduction in signal intensity indicates that signal collection volume was reduced by one-third. The optrode was shown to be sensitive enough to detect fluorescently labeled cell concentrations of 1.9 × 10(4) CFU/mL, indicating it is suitable for detecting typical concentrations of degrader organisms reported in bioremediation trials. The effect of fluorophore photobleaching was characterized for different fluorescent proteins and demonstrated a linear relationship to cell concentration, meaning the effect can be accounted for within methods of fluorescence collection and analysis. Proof of concept is provided for all aspects of this research, which represents an important step toward the goal of achieving a complete, nondestructive, in situ monitoring system to characterize all aspects of microbial activity and gene expression.

Naphthalene vapor sorption by polymer nanoparticles with molecularly imprinted shells

The process of naphthalene adsorption from the gas phase by layers of core-shell polymer nanoparticles obtained with the use of molecular imprinting methods is studied by the fluorescent analysis method. Within the pseudo-second-order kinetic model of sorption, data on the rate constants of fluorescence change are obtained, primary regularities of the sorption process are determined, and the presence of selective recognition sites in the shells of nanoparticles is proven.

Thermal imaging study of scalar transport in shallow wakes

The thermal imaging technique relies on the usage of infrared signal to detect the temperature field. Using temperature as a flow tracer, thermography is used to investigate the scalar transport in the shallow-water wake generated by an emergent circular cylinder. Thermal imaging is demonstrated to be a good quantitative flow visualization technique for studying turbulent mixing phenomena in shallow waters. A key advantage of the thermal imaging method over other scalar measurement techniques, such as the Laser Induced Fluorescence (LIF) and Planar Concentration Analysis (PCA) methods, is that it involves a very simple experimental setup. The dispersion characteristics captured with this technique are found to be similar to past studies with traditional measurement techniques.

Determination of the drug–DNA binding modes using fluorescence-based assays

Therapeutic drugs and environmental pollutants may exhibit high reactivity toward DNA bases and backbone. Understanding the mechanisms of drug–DNA binding is crucial for predicting their potential genotoxicity. We developed a fluorescence analytical method for the determination of the preferential binding mode for drug–DNA interactions. Two nucleic acid dyes were employed in the method: TO-PRO-3 iodide (TP3) and 4′,6-diamidino-2-phenylindole (DAPI). TP3 binds DNA by intercalation, whereas DAPI exhibits minor groove binding. Both dyes exhibit significant fluorescence magnification on binding to DNA. We evaluated the DNA binding constant, Kb, for each dye. We also performed fluorescence quenching experiments with 11 molecules of various structures and measured a C50 value for each compound. We determined preferential binding modes for the aforementioned molecules and found that they bound to DNA consistently, as indicated by other studies. The values of the likelihood of DNA intercalation were correlated with the partition coefficients of the molecules. In addition, we performed nuclear magnetic resonance (NMR) studies of the interactions with calf thymus DNA for the three molecules. The results were consistent with the fluorescence method described above. Thus, we conclude that the fluorescence method we developed provides a reliable determination of the likelihoods of the two different DNA binding modes.

Mixed Micellar Electrokinetic Chromatographic Analysis of Colistin, Polypeptide Antibiotic, Using Laser-Induced Fluorescence Detection

The main goal of this work was to quantify the detection of colistin at low levels in urine samples through the practical application of mixed surfactant micellar electrokinetic chromatography–laser-induced fluorescence (MEKC-LIF) analysis method using its advantage of sensitivity and to examine direct injection of biological samples. Colistin (po- lymyxin E) has neither strong UV chromophore nor fluorophore. So, its assay for metabolism, pharmacokinetics studies for bioavailability and bioequivalence are difficult because of poor detectability. Therefore an enhanced UV or fluores-cence detection by chemical derivatization is required. MEKC-LIF method was proposed for colistin with a 488/520 nm argon-ion laser using a pre-CE derivatization with fluorescein isothiocyanate (FITC). Borate buffer was used as background buffer (BGB). The different parameters affecting the proposed derivatization reaction including concentration of the derivatizing reagent, reaction time and temperature were studied and optimized. The derivative was stable for up to 3 days. Different micelles (TX-100 and SDS) were examined as BGB additives separately but negative-charged mixed micelles (SDS/TX-100) were shown to be the best additive to BGB for the analysis of colistin particularly in human urine as they enhance both selectivity and sensitivity of the proposed method. BGB was used with pH 9.5, 10 kV, 8 s inj time, capillary length 75 cm × 75 μm ID (66 cm effective length), detection was LIF Ex 488 nm; Em 520 nm. The method was applied to colistin analysis in human urine and the recovery was > 98% (n = 5). LOD and LOQ in urine after pre-column derivatization using FITC were 100 and 250 ng/ml, respectively. Urine samples were analysed by direct injection without sample pre-treatment. The mechanism of enhancement of fluorescence of the derivative by surfactant was proposed.

A Study of Microproperties of Historical Brick Material and Qualitative Correlation between Strength and Pore Distribution

Experimental materials in this paper are taken from songyue temple and fawang temple which are both in henan province, X ray fluorescence analysis method is adopted to analysis the chemical ingredients of the historical bricks come from two temples respectively; strength of the bricks come from two temples are compared also; then a model of porous bodies connected parallel is established to reflect the pore distribution of material, the qualitative relationship between strength of material and porosity/pore distribution is derived; mercury intrusion method is used at last to get the porosity and pore microproperties of the historical bricks come from two temples, results show that porosity and microproperties of pores are important factors that affect the characteristics of historical brick material.

A Study of Microproperties of Historical Brick Material and Qualitative Correlation between Strength and Pore Distribution

Experimental materials in this paper are taken from songyue temple and fawang temple which are both in henan province, X ray fluorescence analysis method is adopted to analysis the chemical ingredients of the historical bricks come from two temples respectively; strength of the bricks come from two temples are compared also; then a model of porous bodies connected parallel is established to reflect the pore distribution of material, the qualitative relationship between strength of material and porosity/pore distribution is derived; mercury intrusion method is used at last to get the porosity and pore microproperties of the historical bricks come from two temples, results show that porosity and microproperties of pores are important factors that affect the characteristics of historical brick material.

Direct laser photo-induced fluorescence determination of bisphenol A

Classical photo-induced fluorescence methods are conducted in two steps: a UV irradiation step in order to form a photo-induced compound followed by its fluorimetric determination. Automated flow injection methods are frequently used for these analyses. In this work, we propose a new method of direct laser photo-induced fluorescence analysis. This new method is based on direct irradiation of the analyte in a fluorimetric cell in order to form a photo-induced fluorescent compound and its direct fluorimetric detection during a short irradiation time. Irradiation is performed with a tuneable Nd:YAG laser to select the optimal excitation wavelength and to improve the specificity. It has been applied to the determination of bisphenol A, an endocrine disrupter compound that may be a potential contaminant for food. Irradiation of bisphenol A at 230 nm produces a photo-induced compound with a much higher fluorescence quantum yield and specific excitation/emission wavelengths. In tap water, the fluorescence of bisphenol A increases linearly versus its concentration and, its determination by direct laser photo-induced fluorescence permits to obtain a low limit of detection of 17 μg L(-1).