High performance UV–visible avalanche photodetector based on single α-MoO3 microbelt/p-Si heterostructure

2021 ◽  
Vol 44 (3) ◽  
Author(s):  
Yi Tian ◽  
Naisen Yu ◽  
Shiyu Du ◽  
Dedi Liu ◽  
Yunfeng Wu
Keyword(s):  
High Performance ◽  
Uv Visible

Quantum Yields for the Photodegradation of Pollutants in Dilute Aqueous Solution: Phenol, 4-Chlorophenol and N-Nitrosodimethylamine

1996 ◽  
Vol 1 (2) ◽  
Author(s):  
Te-Fu L. Ho ◽  
James R. Bolton ◽  
Ewa Lipczynska-Kochany
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Quantum Yield ◽  
High Performance ◽  
Flash Photolysis ◽  
Quantum Yields ◽  
Visible Absorption ◽  
Dilute Aqueous Solution ◽  
Uv Visible ◽  
Photolysis Of Phenol

AbstractA broadband method has been applied to determine the quantum yields for the photochemical removal of three common pollutants: phenol, 4-chlorophenol and N-nitrosodimethylamine (NDMA) in dilute aqueous solution. Flash photolysis (xenon flash lamps) was used to cause a significant amount of photolysis without photolyzing intermediates. The analysis of reactant depletion following a single flash was carried out by high- performance liquid chromatography (HPLC) or UV/visible absorption spectroscopy. The method for determining quantum-yields employed p-benzoquinone as an actinometer and was validated by determining the average (200-400 nm) quantum yield for the generation of hydroxyl radicals from the photolysis of hydrogen peroxide (0.90 ± 0.10) and the quantum yields for the photolysis of phenol (0.13 ± 0.02) and 4-chlorophenol (0.24 ± 0.04). The values determined agree very well with the literature ones obtained with monochromatic radiation. The quantum yield for the direct photolysis of NDMA was found to be 0.11 ± 0.03 at neutral pH and 0.27 ± 0.02 at pH 2-4. Under conditions where hydrogen peroxide is the principal absorber, the NDMA quantum yield is 0.32 ± 0.04, independent of pH in the range 2-8.

scholarly journals Sensitive Mercury Speciation by Reversed-Phase Column High-Performance Liquid Chromatography with UV-Visible Detection After Solid-Phase Extraction Using 6-Mercaptopurine and Dithizone

2008 ◽  
Vol 91 (6) ◽  
pp. 1453-1458 ◽  
Author(s):  
Hamid Hashemi-Moghaddam ◽  
Mohamad Saber-Tehrani
Keyword(s):  
High Performance ◽  
Solid Phase ◽  
Reversed Phase ◽  
Phase Extraction ◽  
Organic Mercury ◽  
Tuna Fish ◽  
Rp Hplc ◽  
Uv Visible ◽  
Phase Column ◽  
Reversed Phase Column

Abstract A highly selective and sensitive method was developed for preconcentration of inorganic and organic mercury compounds followed by reversed-phase column high-performance liquid chromatography (RP-HPLC) with UV-visible detection. The method was based on the reaction of mercury with 6-mercaptopurine and solid-phase extraction (SPE) of the complex on an octadecylsilane (C18) cartridge. The complex was then treated with ammoniacal dithizone solution, and the complexes of inorganic and organic mercury with dithizone were eluted by methanol. The speciation analysis of methylmercury (MeHg), phenylmercury (PhHg), and inorganic Hg (II) was carried out by RP-HPLC. Some experimental variables that influence the SPE and derivatization, such as pH, chelating and derivatizing agent concentration, and surfactant addition, were investigated. The calibration graphs of MeHg, PhHg, and Hg (II) were linear [correlation coefficient (r) > 0.999] from the detection limits (0.12, 0.16, and 0.14 ng) to 8.5, 6.0, and 6.7 ng Hg, respectively. By applying the SPE procedure, a 100-fold concentration of the sample was obtained. The procedure was applied to sea water and tuna fish samples. The method's accuracy was investigated by using tuna fish certified reference material BCR 464 and by spiking the samples with different amounts of MeHg, PhHg, and Hg (II). The average recoveries of MeHg, PhHg, and Hg (II) from spiked samples (0.12.0 g/L Hg) were 96 4, 98 3, and 104 4, respectively.

scholarly journals UV-visible photodegradation of naproxen in water – Structural elucidation of photoproducts and potential toxicity

2020 ◽  
Vol 26 (6) ◽  
pp. 400-408
Author(s):  
Noemi Cazzaniga ◽  
Zsuzsanna Varga ◽  
Edith Nicol ◽  
Stéphane Bouchonnet
Keyword(s):  
Mass Spectrometry ◽  
High Performance ◽  
Vibrio Fischeri ◽  
Software Tool ◽  
In Vitro Assays ◽  
Naphthaleneacetic Acid ◽  
Ion Cyclotron Resonance ◽  
Potential Toxicity ◽  
Uv Visible

The UV-visible photodegradation of Naproxen (6-methoxy-α-methyl-2-naphthaleneacetic acid, CAS: 22204-53-1), one of the most used and detected non-steroidal anti-inflammatory drugs (NSAIDs) in the world, and its ecotoxicological consequences were investigated in an aqueous medium. The photo-transformation products were analyzed and the structures of photoproducts were elucidated using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) and high-performance liquid chromatography coupled with ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR-MS). Seven photoproducts were detected and characterized, photo-transformation mechanisms have been postulated to rationalize their formation under irradiation. In silico Q.S.A.R. (Quantitative Structure-Activity Relationship) toxicity predictions were performed with the Toxicity Estimation Software Tool (T.E.S.T.) and in vitro assays were carried out on Vibrio fischeri bacteria. Some of the obtained photoproducts exhibit higher potential toxicity than Naproxen itself but the whole toxicity of the irradiated solution is not of major concern.

scholarly journals Photodegradation of Chloridazon Using Coreshell Magnetic Nanocompsites

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Dina Mamdouh Fouad ◽  
Mona Bakr Mohamed
Keyword(s):  
High Performance ◽  
Magnetic Nanoparticle ◽  
Chemical Methods ◽  
Tem Analysis ◽  
Photodegradation Rate ◽  
Transmission Electron ◽  
Visible Spectra ◽  
Uv Visible ◽  
Particle Size And Shape ◽  
Sun Light

A new synthesized magnetic nanoparticle of Fe3O4and coreshell Fe3O4@Au is prepared chemically. A comparative study between the photocatalytic activity between Fe3O4and core shell Au-Fe3O4nanoparticles has been studied on the effect of UV and sun light on the photodegradation of chloridazon. The particle has been prepared using chemical methods and the particle size and shape have been examined via transmission electron microscopy (TEM). Analysis of the degradation of 20 ppm chloridazon under ultraviolet (UV) and visible light was analyzed with high-performance liquid chromatography (HPLC) and UV-Visible Spectra. Influence of different parameters on the activity photodegradation rate has been studied. The results indicate that the Fe3O4@Au nanoparticles are much more active catalyst in presence of sun light than pure Fe3O4nanomaterials which have maximum absorption at 560 nm.

scholarly journals Degradation of Benzo[a]pyrene by Mycobacterium vanbaalenii PYR-1

2004 ◽  
Vol 70 (1) ◽  
pp. 340-345 ◽  
Author(s):  
Joanna D. Moody ◽  
James P. Freeman ◽  
Peter P. Fu ◽  
Carl E. Cerniglia
Keyword(s):  
High Performance ◽  
Culture Media ◽  
Optical Purity ◽  
Fission Products ◽  
Reversed Phase ◽  
Environmental Pollutant ◽  
Ring Fission ◽  
Uv Visible ◽  
Derivatives Of ◽  
Absolute Stereochemistry

ABSTRACT Metabolism of the environmental pollutant benzo[a]pyrene in the bacterium Mycobacterium vanbaalenii PYR-1 was examined. This organism initially oxidized benzo[a]pyrene with dioxygenases and monooxygenases at C-4,5, C-9,10, and C-11,12. The metabolites were separated by reversed-phase high-performance liquid chromatography (HPLC) and characterized by UV-visible, mass, nuclear magnetic resonance, and circular dichroism spectral analyses. The major intermediates of benzo[a]pyrene metabolism that had accumulated in the culture media after 96 h of incubation were cis-4,5-dihydro-4,5-dihydroxybenzo[a]pyrene (benzo[a]pyrene cis-4,5-dihydrodiol), cis-11,12-dihydro-11,12-dihydroxybenzo[a]pyrene (benzo[a]pyrene cis-11,12-dihydrodiol), trans-11,12-dihydro-11,12-dihydroxybenzo[a]pyrene (benzo[a]pyrene trans-11,12-dihydrodiol), 10-oxabenzo[def]chrysen-9-one, and hydroxymethoxy and dimethoxy derivatives of benzo[a]pyrene. The ortho-ring fission products 4-formylchrysene-5-carboxylic acid and 4,5-chrysene-dicarboxylic acid and a monocarboxylated chrysene product were formed when replacement culture experiments were conducted with benzo[a]pyrene cis-4,5-dihydrodiol. Chiral stationary-phase HPLC analysis of the dihydrodiols indicated that benzo[a]pyrene cis-4,5-dihydrodiol had 30% 4S,5R and 70% 4R,5S absolute stereochemistry. Benzo[a]pyrene cis-11,12-dihydrodiol adopted an 11S,12R conformation with 100% optical purity. The enantiomeric composition of benzo[a]pyrene trans-11,12-dihydrodiol was an equal mixture of 11S,12S and 11R,12R molecules. The results of this study, in conjunction with those of previously reported studies, extend the pathways proposed for the bacterial metabolism of benzo[a]pyrene. Our study also provides evidence of the stereo- and regioselectivity of the oxygenases that catalyze the metabolism of benzo[a]pyrene in M. vanbaalenii PYR-1.

High-Performance UV–Visible–NIR Broad Spectral Photodetectors Based on One-Dimensional In2Te3 Nanostructures

Nano Letters ◽  
2012 ◽  
Vol 12 (9) ◽  
pp. 4715-4721 ◽  
Author(s):  
Zhenxing Wang ◽  
Muhammad Safdar ◽  
Chao Jiang ◽  
Jun He
Keyword(s):  
High Performance ◽  
One Dimensional ◽  
Uv Visible

Interaction of 5-aminosalicylic acid with nitrous acid: formation of the diazonium derivative and nitric oxide release

2011 ◽  
Vol 89 (6) ◽  
pp. 628-638 ◽  
Author(s):  
C. López-Alarcón ◽  
E. Lissi ◽  
P. Hoffmann ◽  
J. Mella ◽  
C.D. Pessoa-Mahana ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrous Acid ◽  
High Performance ◽  
Low Ph ◽  
Aminosalicylic Acid ◽  
Nitric Oxide Release ◽  
First Order ◽  
No Formation ◽  
Uv Visible ◽  
A Minor

The reaction of 5-aminosalicylic acid (5-ASA) with nitrous acid has been studied at low pH under conditions that simulate a gastric environment. The course of the reaction was followed by UV–visible and fluorescence spectroscopy and the products were analyzed by high performance liquid chromatography (HPLC) with UV–visible and mass spectroscopic detectors. In addition, the formation of nitric oxide (NO) was estimated electrochemically. 5-ASA was readily consumed in a process catalyzed by chloride and thiocyanate, whose rate is first order in 5-ASA and second order in nitrous acid. 2-Hydroxy-5-diazonium benzoic acid (diazonium derivative) and NO were detected as products of the reaction. From the NO formation profiles, it is concluded that NO is produced as a minor product in a process parallel to the path that leads to generation of the diazonium derivative. While the formation of NO could be beneficial for the protection of the stomach, the generation of the diazonium derivative could be considered a potentially toxic process.

scholarly journals Standardization Study of Ghritas

2004 ◽  
Vol 1 (3) ◽  
pp. 151-157 ◽  
Author(s):  
D. Shaila ◽  
M. K. Santosh ◽  
T. Chandrakumar ◽  
I. Sanjeeva Rao
Keyword(s):  
Qualitative Analysis ◽  
High Performance ◽  
Solvent System ◽  
High Performance Liquid Chromatographic ◽  
Hplc Fingerprint ◽  
Visible Spectrophotometry ◽  
Mother And Child ◽  
Hexane Extracts ◽  
Uv Visible ◽  
Liquid Chromatographic

The standardization of ghritas such as amritaprasa ghrita, brahmi ghrita, chagalyadi ghrita and phala ghrita has been studied. These ghritas are the important Ayurvedic formulations used for peri-natal care of mother and child health. Standardization of ghritas were achieved by organoleptic study, physico-chemical analysis, qualitative analysis, thin layer chromatography (TLC), UV - visible spectrophotometry and high performance liquid chromatographic (HPLC) fingerprint studies. Qualitative analysis of alcoholic extracts of all the four ghritas shows the presence of glycosides and hexane extracts shows the presence of glycosides and steroids. TLC study of ghritas was carried out in toulene-ethyl acetate solvent system. Hexane extracts of ghritas were used for UV- visible spectrophotometry and qualitative HPLC fingerprint study.

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