scholarly journals Mass spectral and theoretical investigations of the transient proton-bound dimers on the cleavage processes of the peptide GHK and its analogues

RSC Advances ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 4077-4086
Author(s):  
Jinhu Wang ◽  
Cheng Wang ◽  
Han Zhang ◽  
Yang Liu ◽  
Tiesheng Shi
Keyword(s):  
Mass Spectrometry ◽  
Theoretical Calculations ◽  
Mass Spectral ◽  
Protonated Peptides ◽  
Fragmentation Mechanisms ◽  
Theoretical Investigations

Fragmentation mechanisms of the singly protonated peptides GHK, GHKH and HGHK have been investigated by mass spectrometry and theoretical calculations.

Theoretical and experimental research on slip and uplift of the timber-concrete composite beam

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 7079-7099
Author(s):  
Jianying Chen ◽  
Guojing He ◽  
Xiaodong (Alice) Wang ◽  
Jiejun Wang ◽  
Jin Yi ◽  
...  
Keyword(s):  
Differential Equations ◽  
Deformation Theory ◽  
Concrete Slab ◽  
Theoretical Calculations ◽  
Structural Element ◽  
Structural Efficiency ◽  
Theoretical Investigations ◽  
New Type ◽  
Interlayer Slip ◽  
Good Agreement

Timber-concrete composite beams are a new type of structural element that is environmentally friendly. The structural efficiency of this kind of beam highly depends on the stiffness of the interlayer connection. The structural efficiency of the composite was evaluated by experimental and theoretical investigations performed on the relative horizontal slip and vertical uplift along the interlayer between composite’s timber and concrete slab. Differential equations were established based on a theoretical analysis of combination effects of interlayer slip and vertical uplift, by using deformation theory of elastics. Subsequently, the differential equations were solved and the magnitude of uplift force at the interlayer was obtained. It was concluded that the theoretical calculations were in good agreement with the results of experimentation.

scholarly journals Desorption/Ionization Fluence Thresholds and Improved Mass Spectral Consistency Measured Using a Flattop Laser Profile in the Bioaerosol Mass Spectrometry of SingleBacillusEndospores

2005 ◽  
Vol 77 (22) ◽  
pp. 7448-7454 ◽  
Author(s):  
Paul T. Steele ◽  
Abneesh Srivastava ◽  
Maurice E. Pitesky ◽  
David P. Fergenson ◽  
Herbert J. Tobias ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectral ◽  
Desorption Ionization ◽  
Bioaerosol Mass Spectrometry ◽  
Laser Profile

Identification of Diels-Alder regioisomers by mass spectrometry coupled with theoretical calculations

1993 ◽  
Vol 28 (7) ◽  
pp. 752-758 ◽  
Author(s):  
C. Cativiela ◽  
J. I. García ◽  
J. Garín ◽  
J. A. Mayoral ◽  
J. Orduna ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Theoretical Calculations ◽  
Diels Alder

Degradation of bacteria mass spectral signals via hydrothermal processing and UV irradiation: relevance to life detection on icy moons

2021 ◽  
Author(s):  
Tara Salter ◽  
Hunter Waite ◽  
Mark Sephton
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Uv Irradiation ◽  
Gas Chromatography Mass Spectrometry ◽  
Xenon Lamp ◽  
Hydrothermal Processing ◽  
Mass Spectral ◽  
Icy Moons ◽  
Chromatography Mass Spectrometry ◽  
Life Detection

<p>The inferred subsurface oceans of the icy moons of Jupiter and Saturn, in particular Europa and Enceladus, may contain conditions suitable for life. Plumes of material have been detected from Enceladus and may also be present on Europa. These plumes could contain molecular signs of habitability that could be detected by mass spectrometers on orbiting spacecrafts, such as the upcoming Europa Clipper mission. However, these molecular markers may have degraded between their production and detection, for example by possible hydrothermalism in the subsurface ocean or by UV irradiation once carried into space by the plume. It is important to look at how the biosignatures degrade under different conditions as degradation processes need to be taken into account when analysing the data from life detection missions. We investigate how these two processes affect the mass spectral signals of terrestrial bacteria.</p> <p>Two cyanobacteria samples, <em>Spirulina</em> and <em>Chlorella</em>, were subjected to hydrothermal processing and UV irradiation. Hydrous pyrolysis was used to simulate hydrothermal degradation. Experiments were carried out for 24 or 72 hours at temperatures between 200 and 300 °C. The pyrolyzed contents were subsequently extracted and analysed with gas chromatography-mass spectrometry (GC-MS). UV irradiation was carried out in a vacuum chamber (10<sup>-2</sup> mbar), using a 300 W short arc xenon lamp at UV to near infrared wavelengths (~250 – 800 nm). After UV irradiation, samples were analysed using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS).</p> <p>Our results show that hydrothermal processing of cyanobacteria affects the compound classes in different ways. Carbohydrate and protein components from the cyanobacteria were significantly affected, with phenol and indole derivatives detected. However, some of the biological fingerprint, such as straight-chain even numbered saturated fatty acids from lipid fragments, remain even at the harshest experimental conditions used in our study. This provides confidence that these diagnostic molecules could be used as fingerprints of biological materials on icy moons.</p>

Differentiation of the Isomeric o-(m- and p-) Nitro-(Chloro- and Bromo-)Benzyl-2,4-(and 2,1-) Disubstituted 2-Thiocytosinium Halides by Electron Impact Ionisation and Fast Atom Bombardment Mass Spectrometry

2009 ◽  
Vol 15 (4) ◽  
pp. 497-506 ◽  
Author(s):  
Tomasz Pospieszny ◽  
Elżbieta Wyrzykiewicz
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Fast Atom Bombardment ◽  
Collision Induced Dissociation ◽  
Mass Measurements ◽  
Fragmentation Pathways ◽  
Mass Spectral ◽  
Fragment Ions ◽  
Accurate Mass Measurements ◽  
Impact Ionisation

Electron ionisation (EI) and fast atom bombardment (FAB) mass spectral fragmentations of nine 2,4-(and 2,1-) disubstituted o-( m- and p-)nitro-(chloro- and bromo-)-2-thiocytosinium halides are investigated. Fragmentation pathways, whose elucidation is assisted by accurate mass measurements and metastable transitions [EI-mass spectrometry (MS)], as well as FAB/collision-induced dissociation (CID) mass spectra measurements are discussed. The correlations between the abundances of the (C11H10N4SO2)+1–3; (C11H10N3SCl)+4–6 and (C11H10N3SBr)+7–9 ions and the selected fragment ions (EI-MS), as well as (C18H16N5SO4)+1–3; (C18H16N3SCl2)+4–6 and (C18H16N3SBr2) + 7–9 ions and the selected ions (C7H6NO2)+1–3; (C7H6Cl)+ 4–6; (C7H6Br)+ 7–9 (FAB-MS) are discussed. The data obtained can be used for distinguishing isomers.

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