Clarification of degradation mechanism on retinal prosthesis using photoelectric dyes coupled to polyethylene film by mass spectrometry

2021 ◽  
pp. 130978
Author(s):  
Koichiro Yamashita ◽  
Mayu Mitsui ◽  
Toshihiko Matsuo ◽  
Tetsuya Uchida
Keyword(s):  
Mass Spectrometry ◽  
Degradation Mechanism ◽  
Retinal Prosthesis ◽  
Polyethylene Film

scholarly journals Photocatalytic Degradation of Trifluralin, Clodinafop-Propargyl, and 1,2-Dichloro-4-Nitrobenzene As Determined by Gas Chromatography Coupled with Mass Spectrometry

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Niyaz A. Mir ◽  
A. Khan ◽  
M. Muneer ◽  
S. Vijayalakhsmi
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Photocatalytic Degradation ◽  
Degradation Mechanism ◽  
Gas Chromatography Mass Spectrometry ◽  
Ionization Mass ◽  
Water Medium ◽  
Fragmentation Pattern ◽  
Chemical Structures ◽  
Clodinafop Propargyl

Phototransformation is considered one of the most key factors affecting the fate of pesticides. Therefore, our study focused on photocatalytic degradation of three selected pesticide derivatives: trifluralin (1), clodinafop-propargyl (2), and 1,2-dichloro-4-nitrobenzene (3). The degradation was carried out in acetonitrile/water medium in the presence of titanium dioxide (TiO2) under continuous purging of atmospheric air. The course of degradation was followed by thin-layer chromatography and gas chromatography-mass spectrometry techniques. Electron ionization mass spectrometry was used to identify the degradation species. GC-MS analysis indicates the formation of several intermediate products which have been characterized on the basis of molecular ion, mass fragmentation pattern, and comparison with NIST library. The photocatalytic degradation of pesticides of different chemical structures manifested distinctly different degradation mechanism. The major routes for the degradation of pesticides were found to be (a) dealkylation, dehalogenation, and decarboxylation, (b) hydroxylation, (c) oxidation of side chain, if present, (d) isomerization and cyclization, (e) cleavage of alkoxy bond, and (f) reduction of triple bond to double bond and nitro group to amino.

scholarly journals Pyrolysis kinetic modelling of abundant plastic waste (PET) and in-situ emissions monitoring

2020 ◽  
Author(s):  
Ahmed I. Osman ◽  
Charlie Farrell ◽  
Ala'a H. Al-Muhtaseb ◽  
Ahmed S. Al-Fatesh ◽  
John Harrison ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Activation Energy ◽  
Kinetic Modelling ◽  
Degradation Mechanism ◽  
Scale Up ◽  
Plastic Waste ◽  
Gaseous Emissions ◽  
Low Carbon ◽  
Pyrolysis Process

Abstract Background: Recycling the ever-increasing plastic waste has become an urgent global concern. One of the most convenient methods for plastic recycling is pyrolysis, owing to its environmentally friendly nature and its intrinsic properties. Understanding the pyrolysis process and the degradation mechanism is crucial for scale-up and reactor design. Therefore, we studied kinetic modelling of the pyrolysis process for one of the most common plastics, polyethylene terephthalate (PET). The focus was to better understand and predict PET pyrolysis when transitioning to a low carbon economy and adhering to environmental and governmental legislation. This work aims at presenting for the first time, the kinetic triplet (activation energy, pre-exponential constant and reaction rate) for the PET pyrolysis using the differential iso-conversional method. This is coupled with the in-situ online tracking of the gaseous emissions using mass spectrometry.Results: The differential iso-conversional method showed activation energy (Ea) values of 165-195 kJ.mol-1, R2 = 0.99659. While the ASTM-E698 showed 165.6 kJ.mol-1 and integral methods such as Flynn-Wall and Ozawa (FWO) (166-180 kJ.mol-1). The in-situ Mass Spectrometry results showed the pyrolysis gaseous emissions which are C1-hydrocarbon and H-O-C=O along with C2 hydrocarbons, C5- C6 hydrocarbons, acetaldehyde, the fragment of O-CH=CH2, hydrogen and water. Conclusions: From the obtained results herein, thermal predictions (isothermal, non-isothermal and step-based heating) were determined based on the kinetic parameters and can be used at numerous scales with a high level of accuracy compared with the literature.

Modelling the visual response to an OUReP retinal prosthesis with photoelectric dye coupled to polyethylene film

2021 ◽  
Author(s):  
Koichiro Yamashita ◽  
Prathima Sundaram ◽  
Tetsuya Uchida ◽  
Toshihiko Matsuo ◽  
Willy Wong
Keyword(s):  
Retinal Prosthesis ◽  
Polyethylene Film ◽  
Visual Response ◽  
Photoelectric Dye

Characterizing the thermal degradation mechanism of two bisphosphoramidates by TGA, DSC, mass spectrometry and first-principle theoretical protocols

2020 ◽  
Vol 1221 ◽  
pp. 128781
Author(s):  
José Luis Castrejón-Flores ◽  
Julieta Reyna-Luna ◽  
Yazmin M. Flores-Martinez ◽  
María Isabel García-Ventura ◽  
Angel Zamudio-Medina ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Thermal Degradation ◽  
Degradation Mechanism ◽  
First Principle ◽  
Thermal Degradation Mechanism

Degradation mechanism study of fluoroquinolones in UV/Fe2+/peroxydisulfate by on-line mass spectrometry

Chemosphere ◽  
2020 ◽  
Vol 239 ◽  
pp. 124737 ◽  
Author(s):  
Jie Jiang ◽  
Dongmei Zhang ◽  
Hong Zhang ◽  
Kai Yu ◽  
Na Li ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Degradation Mechanism ◽  
Mechanism Study ◽  
Line Mass ◽  
On Line

How SIMS microscopy can be used in medicine

1992 ◽  
Vol 50 (2) ◽  
pp. 1602-1603
Author(s):  
Philippe Fragu
Keyword(s):  
Mass Spectrometry ◽  
Biomedical Applications ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Elements ◽  
Biological Applications ◽  
The Past ◽  
Potential Source ◽  
Secondary Ion ◽  
Chemical Integrity ◽  
Scientific Endeavour

The identification, localization and quantification of intracellular chemical elements is an area of scientific endeavour which has not ceased to develop over the past 30 years. Secondary Ion Mass Spectrometry (SIMS) microscopy is widely used for elemental localization problems in geochemistry, metallurgy and electronics. Although the first commercial instruments were available in 1968, biological applications have been gradual as investigators have systematically examined the potential source of artefacts inherent in the method and sought to develop strategies for the analysis of soft biological material with a lateral resolution equivalent to that of the light microscope. In 1992, the prospects offered by this technique are even more encouraging as prototypes of new ion probes appear capable of achieving the ultimate goal, namely the quantitative analysis of micron and submicron regions. The purpose of this review is to underline the requirements for biomedical applications of SIMS microscopy.Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue.

Imaging of Al-Li-Cu alloys with a Scanning Ion Microprobe

1990 ◽  
Vol 48 (2) ◽  
pp. 314-315
Author(s):  
K.K. Soni ◽  
D.B. Williams ◽  
J.M. Chabala ◽  
R. Levi-Setti ◽  
D.E. Newbury
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Equilibrium Phase ◽  
Icosahedral Symmetry ◽  
Ion Microprobe ◽  
X Ray ◽  
Cu Alloys ◽  
Two Phases ◽  
The University ◽  
Secondary Ion

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.

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