Nitrogen Gas Purging for the Deoxygenation of Polyaromatic Hydrocarbon Solutions in Cyclohexane for Routine Fluorescence Analysis

During routine fluorescence analysis, the presence of dissolved oxygen in solutions can result in the dynamic quenching of a fluorophore's emission through collisional deexcitation of the fluorophore's excited state. In order to avoid this type of fluorescence quenching, dissolved oxygen is often removed from solutions by an inert gas purging procedure. However, the details and quantification of this purging process are often limited in fluorescence studies. In this work, standard 10 mm × 10 mm fluorescence cuvettes are filled with polyaromatic hydrocarbon (PAH) solutions in cyclohexane and purged using nitrogen gas, and the experimental purging parameters (nitrogen flow rate, amount of volatile solvent loss, and rate of oxygen removal) are measured and analyzed. For experimental conditions similar to those used in this study, we are able to provide useful guidelines for the deoxygenation of solutions, specifically the purge times required for solutions of fluorophores with various fluorescence lifetimes. Enhancement factors, or F0/ F values (the ratio of fluorescence intensity of a completely deoxygenated solution to the fluorescence intensity of an aerated solution), for chrysene, phenanthrene, naphthalene, and pyrene solutions in cyclohexane were found to be 3.61 ± 0.02, 4.17 ± 0.02, 7.63 ± 0.07, and 21.81 ± 0.35, respectively.

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Algae-Assisted Microbial Desalination Cell: Analysis of Cathode Performance and Desalination Efficiency Assessment

Processes ◽

10.3390/pr9112011 ◽

2021 ◽

Vol 9 (11) ◽

pp. 2011

Author(s):

David Ewusi-Mensah ◽

Jingyu Huang ◽

Laura Katherin Chaparro ◽

Pau Rodenas ◽

Marina Ramírez-Moreno ◽

...

Keyword(s):

Dissolved Oxygen ◽

Chlorella Vulgaris ◽

Coulombic Efficiency ◽

Geobacter Sulfurreducens ◽

Dark Phase ◽

Water Production ◽

Light Phase ◽

Experimental Conditions ◽

Residual Concentration ◽

Microbial Desalination Cell

Algae-assisted microbial desalination cells represent a sustainable technology for low-energy fresh water production in which microalgae culture is integrated into the system to enhance oxygen reduction reaction in the cathode chamber. However, the water production (desalination rate) is low compared to conventional technologies (i.e., reverse osmosis and/or electrodialysis), as biocathodes provide low current generation to sustain the desalination process. In this sense, more research efforts on this topic are necessary to address this bottleneck. Thus, this study provides analysis, from the electrochemical point of view, on the cathode performance of an algae-assisted microbial desalination cell (MDC) using Chlorella vulgaris. Firstly, the system was run with a pure culture of Chlorella vulgaris suspension in the cathode under conditions of an abiotic anode to assess the cathodic behavior (i.e., cathode polarization curves in light-dark conditions and oxygen depletion). Secondly, Geobacter sulfurreducens was inoculated in the anode compartment of the MDC, and the desalination cycle was carried out. The results showed that microalgae could generate an average of 9–11.5 mg/L of dissolved oxygen during the light phase, providing enough dissolved oxygen to drive the migration of ions (i.e., desalination) in the MDC system. Moreover, during the dark phase, a residual concentration of oxygen (ca. 5.5–8 mg/L) was measured, indicating that oxygen was not wholly depleted under our experimental conditions. Interestingly, the oxygen concentration was restored (after complete depletion of dissolved oxygen by flushing with N2) as soon as microalgae were exposed to the light phase again. After a 31 h desalination cycle, the cell generated a current density of 0.12 mA/cm2 at an efficiency of 60.15%, 77.37% salt was removed at a nominal desalination rate of 0.63 L/m2/h, coulombic efficiency was 9%, and 0.11 kWh/m3 of electric power was generated. The microalgae-assisted biocathode has an advantage over the air diffusion and bubbling as it can self-sustain a steady and higher concentration of oxygen, cost-effectively regenerate or recover from loss and sustainably retain the system’s performance under naturally occurring conditions. Thus, our study provides insights into implementing the algae-assisted cathode for sustainable desalination using MDC technology and subsequent optimization.

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Grazing Incidence X-ray Fluorescence Analysis with Monochromatic Radiation

Advances in X-ray Analysis ◽

10.1154/s0376030800014348 ◽

1990 ◽

Vol 34 ◽

pp. 71-80 ◽

Cited By ~ 1

Author(s):

Manfred Schuster

Keyword(s):

Penetration Depth ◽

Fluorescence Intensity ◽

Dopant Concentration ◽

Fluorescence Analysis ◽

Analytical Description ◽

Grazing Incidence ◽

Concentration Profiles ◽

Angle Of Incidence ◽

X Ray ◽

Si Wafer

AbstractX-ray fluorescence excited by a monochromatic collimated Mo-Kα beam at grazing incidence is measured as a function of the angle of incidence. Monochromatic excitation guarantees a well-defined penetration depth and enables a simple analytical description of the fluorescence intensity. This method is applied to a system of thin Cu and Ti metallization layers on a Si wafer and to As dopant concentration profiles in Si wafers.Thereby, the effect of annealing can be analyzed non-destructively.

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2-(2'- Chloro Phenyl)- 5- (2'-Hydroxyl Phenyl)-1,3,4-Oxadiazole as a Florescent Probe for DNA Determination

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.301-303.361 ◽

2011 ◽

Vol 301-303 ◽

pp. 361-365

Author(s):

Mei Ding ◽

Ying Jie Lei ◽

Ou Yang Jie

Keyword(s):

Experimental Data ◽

Fluorescence Quenching ◽

Quantitative Determination ◽

Fluorescent Probe ◽

Fluorescence Intensity ◽

Dna Analysis ◽

Fluorescence Spectrometry ◽

Experimental Conditions ◽

Convenient Synthesis

In recent years, fluorescence spectrometry was widely used in quantitative determination of DNA. In this paper, a convenient synthesis of a new fluorescent 2-(2'- Chloro phenyl)- 5- (2'- hydroxyl phenyl)-1,3,4-oxadiazole (HOXD) was realized. Experimental data showed that fluorescence of HOXD could be quenched by DNA and the decreased fluorescence intensity of HOXD resulting from fluorescence quenching is proportional to DNA concentrations suggesting that HOXD could be used as a new fluorescent probe for quantitative determination of DNA. Optimal experimental conditions for DNA analysis were also studied in the paper.

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EFFECT OF NITROGEN DOPING ON FRICTION AND WEAR PROPERTIES OF THICK TETRAHEDRAL AMORPHOUS CARBON COATING

Surface Review and Letters ◽

10.1142/s0218625x18502268 ◽

2019 ◽

Vol 26 (07) ◽

pp. 1850226

Author(s):

HOJUN RYU ◽

WOO YOUNG LEE ◽

JONGKUK KIM ◽

YOUNG-JUN JANG

Keyword(s):

Amorphous Carbon ◽

Flow Rate ◽

Nitrogen Doping ◽

Friction And Wear ◽

Wear Scar ◽

Low Flow ◽

Nitrogen Flow ◽

Nitrogen Flow Rate ◽

Nitrogen Gas ◽

Tetrahedral Amorphous Carbon

In the present study, the coating was deposited by the filtered cathode vacuum arc (FCVA) plasma technique, and the effect of the nitrogen gas doping on the friction and wear performances of the thick layer of nitrogen-doped tetrahedral amorphous carbon (ta-C:N) coating were investigated. The tribological behavior of the coating was investigated by sliding an SUJ2 ball over the coating in a ball-on-disk tribo-meter. The experimental results revealed that doping using a high nitrogen gas flow rate improved the wear resistance of the coating, while a low flow rate of 0–10 sccm increased the coefficient of friction (CoF) and wear rate dramatically decreased when the nitrogen flow rate was increased to 30–40 sccm. This was due to the nitrogen-induced phase transformation, resulting in the production of a graphite-like structure in the interface between disk and SUJ2 ball. The widths of the wear track and wear scar were also observed to decrease with increasing nitrogen flow rate. Moreover, the G-peaks of the wear scar around the SUJ2 ball on the worn surface increased with increasing nitrogen doping.

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Use of FT-IR for the Quantification of Water in Biomolecules

Applied Spectroscopy ◽

10.1366/0003702944029974 ◽

1994 ◽

Vol 48 (7) ◽

pp. 818-821 ◽

Cited By ~ 5

Author(s):

Teiki Iwaoka ◽

Fumiko Tabata ◽

Shinya Tsutsumi

Keyword(s):

Water Absorption ◽

Reference Spectrum ◽

Nitrogen Gas ◽

Experimental Conditions ◽

Ir Spectrometry ◽

Loss Of Weight ◽

Biological Compounds ◽

Ft Ir

Water (10−3 mg H2O in 1 mg of biopolymer) was extracted from biological compounds with acetonitrile and determined by FT-IR spectrometry with the use of a KBr transmission cell. A nitrogen-gas-purged glove box was employed during the extraction to avoid errors due to water absorption from ambient laboratory air. The subtractive compensation for concomitant water in acetonitrile was further accomplished by using a reference spectrum of acetonitrile kept under the same experimental conditions as those for preparing the acetonitrile extracts of water from the testing samples. This technique was applied to the quantification of water in peptides and enzymes. The advantages of this technique over the Karl Fisher titration are discussed, along with measurements for loss of weight on drying in vacuo.

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Metmyoglobin Oxidation during Electron Transport Reactions in Mitochondria

The Journal of General Physiology ◽

10.1085/jgp.48.4.685 ◽

1965 ◽

Vol 48 (4) ◽

pp. 685-698 ◽

Cited By ~ 7

Author(s):

Ann E. Kaplan-Bresler

Keyword(s):

Hydrogen Peroxide ◽

Electron Transport ◽

Dissolved Oxygen ◽

Heart Muscle ◽

Absorption Peak ◽

Experimental Conditions ◽

Simultaneous Oxidation

Studies of the intracellular role of myoglobin were carried out by recording spectrophotometric changes in acid metmyoglobin and oxymyoglobin during electron transport reactions with mitochondria prepared from pigeon heart muscle by the method of Chance and Hagihara. The absorption peak of metmyoglobin at 409 mµ disappeared when substrate was added to normal or antimycin-inhibited preparations, and was replaced by a new maximum at 423 to 424 mµ, identified as due to the oxidation to ferrylmyoglobin. Further investigation revealed that the oxidation of metmyoglobin took place with the simultaneous oxidation of reduced flavoprotein. Hydrogen peroxide, formed by the reaction of reduced flavoprotein with oxygen, was considered to be the probable intermediate for the oxidation of metmyoglobin in experiments in which catalase was added as a competitor for the oxidant. When DPNH was added to the reaction mixture, the reductant acted to resynthesize the ferri-derivative by reaction with ferrylmyoglobin. Oxymyoglobin could not be used in place of metmyoglobin in these systems. Under the experimental conditions, oxymyoglobin dissociated when dissolved oxygen was depleted from the medium by enzyme oxidations; the resultant ferromyoglobin underwent oxidation to metmyoglobin.

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The Effect of Pyrolysis Temperature on Copyrolysis of Lignite and Pistachio Seed in a Fixed-bed Reactor

International Journal of Geology ◽

10.46300/9105.2021.15.7 ◽

2021 ◽

Vol 15 ◽

pp. 49-52

Author(s):

Özlem Onay

Keyword(s):

Elemental Analysis ◽

Pyrolysis Temperature ◽

Fixed Bed ◽

Product Distribution ◽

The Other ◽

Fixed Bed Reactor ◽

Oil Yield ◽

Pyrolysis Oil ◽

Nitrogen Gas ◽

Experimental Conditions

Co-pyrolysis of lignite and pistachio seed (CPLPS) under nitrogen gas was performed in a Heinze retort. The effect of pyrolysis temperature on product distribution of CPLPS investigated under heating rate of 10°Cmin-1 and blending ratio of 50(wt)%. Biomass is higher yield to be pyrolyzed than lignite and addition of biomass promotes the pyrolysis of lignite. In the range of the experimental conditions investigated the yield of the product is proportional to pyrolysis temperature. On the other hand, considerable synergetic effects were observed during the co-pyrolysis in a fixed bed reactor leading to increase in oil yield. Maximum pyrolysis oil yield of 27.2% was obtained at pyrolysis temperature of 550°C. The obtained oils are characterized by GC, and elemental analysis.

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Catchment-scale fluorescence water quality determination

Water Science & Technology ◽

10.2166/wst.2005.0319 ◽

2005 ◽

Vol 52 (9) ◽

pp. 199-207 ◽

Cited By ~ 4

Author(s):

A. Baker ◽

R. Inverarity ◽

D. Ward

Keyword(s):

Water Quality ◽

Dissolved Oxygen ◽

Fluorescence Intensity ◽

Wastewater Treatment Plants ◽

Oxygen Demand ◽

Water Quality Assessment ◽

Ammonia Concentration ◽

Catchment Scale ◽

Organic Matter Pool ◽

Portable Spectrometers

Chemical water quality determinants and river water fluorescence were determined on the River Tyne, northeast England. Statistically significant relationships between nitrate (r=0.87), phosphate (r=0.80), ammonia (r=0.70), biochemical oxygen demand (BOD) (r=0.85) and dissolved oxygen (r=−0.65) and tryptophan-like fluorescence intensity were observed. The strongest correlations are between tryptophan-like intensity and nitrate and phosphate, which in the Tyne catchment derive predominantly from point and diffuse source sewage inputs. The correlation between BOD and the tryptophan-like fluorescence intensity suggests that this fluorescence centre is related to the bioavailable or labile dissolved organic matter pool. The weakest correlations are observed between tryptophan-like fluorescence intensity and ammonia concentration and dissolved oxygen. The weaker correlation with ammonia is due to good ammonia treatment within the wastewater treatment plants within the catchment, and that with dissolved oxygen due to the natural aeration of the river such that this is not a good indicator of water quality. Mean annual tryptophan-like fluorescence intensity, measured by both bench and portable spectrometers, agrees well with the General Water Quality Assessment as determined by the England and Wales environmental regulators, the Environment Agency.

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