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https://www.readbyqxmd.com/read/29735103/identification-of-key-odorants-responsible-for-chestnut-like-aroma-quality-of-green-teas
#1
Yin Zhu, Hai-Peng Lv, Chen-Yang Shao, Suyoung Kang, Yue Zhang, Li Guo, Wei-Dong Dai, Jun-Feng Tan, Qun-Hua Peng, Zhi Lin
A chestnut-like aroma is widely considered an important indicator of an excellent-quality green tea; however, the key odorants responsible for chestnut-like aroma have never been systematically studied and remain unknown. In this study, the aroma components of green teas and Chinese chestnuts were analyzed using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS), and 58 compounds were identified as common aroma components among green teas, boiled Chinese chestnuts, roasted Chinese chestnuts and raw Chinese chestnuts...
June 2018: Food Research International
https://www.readbyqxmd.com/read/29723468/dart-ms-a-new-analytical-technique-for-forensic-paint-analysis
#2
Mark Maric, James Marano, Robert Bernard Cody, Candice Bridge
Automotive paint evidence is one of the most significant forms of evidence obtained in automotive related incidents. Therefore, the analysis of automotive paint evidence is imperative in forensic casework. Most analytical schemes for automotive paint characterization involve optical microscopy, followed by infrared spectroscopy and pyrolysis-gas chromatography mass spectrometry (py-GCMS) if required. The main drawback with py-GCMS aside from its destructive nature, is that this technique is relatively time intensive in comparison to other techniques...
May 3, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29720313/analysis-of-inorganic-nanoparticles-by-single-particle-inductively-coupled-plasma-time-of-flight-mass-spectrometry
#3
Lyndsey Hendriks, Alexander Gundlach-Graham, Detlef Günther
Due to the rapid development of nanotechnologies, engineered nanomaterials (ENMs) and nanoparticles (ENPs) are becoming a part of everyday life: nanotechnologies are quickly migrating from laboratory benches to store shelves and industrial processes. As the use of ENPs continues to expand, their release into the environment is unavoidable; however, understanding the mechanisms and degree of ENP release is only possible through direct detection of these nanospecies in relevant matrices and at realistic concentrations...
April 25, 2018: Chimia
https://www.readbyqxmd.com/read/29699672/essential-oils-eos-pressurized-liquid-extracts-ple-and-carbon-dioxide-supercritical-fluid-extracts-sfe-co-2-from-algerian-thymus-munbyanus-as-valuable-sources-of-antioxidants-to-be-used-on-an-industrial-level
#4
Hamdi Bendif, Khaoula Adouni, Mohamed Djamel Miara, Renata Baranauskienė, Paulius Kraujalis, Petras Rimantas Venskutonis, Seyed Mohammad Nabavi, Filippo Maggi
The aim of this study was to demonstrate the potential of extracts from Algerian Thymus munbyanus as a valuable source of antioxidants for use on an industrial level. To this end, a study was conducted on the composition and antioxidant activities of essential oils (EOs), pressurized liquid extracts (PLE) and supercritical fluid extracts (SFE-CO2 ) obtained from Thymus munbyanus subsp. coloratus (TMC) and subsp. munbyanus (TMM). EOs and SFE-CO2 extracts were analysed by GC-FID and GC×GC-TOFMS revealing significant differences...
September 15, 2018: Food Chemistry
https://www.readbyqxmd.com/read/29620160/metabolome-analysis-of-esophageal-cancer-tissues-using-capillary-electrophoresis-time-of-flight-mass-spectrometry
#5
Masanori Tokunaga, Kenjiro Kami, Soji Ozawa, Junya Oguma, Akihito Kazuno, Hayato Miyachi, Yoshiaki Ohashi, Masatoshi Kusuhara, Masanori Terashima
Reports of the metabolomic characteristics of esophageal cancer are limited. In the present study, we thus conducted metabolome analysis of paired tumor tissues (Ts) and non-tumor esophageal tissues (NTs) using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS). The Ts and surrounding NTs were surgically excised pair-wise from 35 patients with esophageal cancer. Following tissue homogenization and metabolite extraction, a total of 110 compounds were absolutely quantified by CE-TOFMS. We compared the concentrations of the metabolites between Ts and NTs, between pT1 or pT2 (pT1-2) and pT3 or pT4 (pT3-4) stage, and between node-negative (pN-) and node-positive (pN+) samples...
March 28, 2018: International Journal of Oncology
https://www.readbyqxmd.com/read/29617312/metabolomic-profiling-of-the-white-violet-and-red-flowers-of-rhododendron-schlippenbachii-maxim
#6
Chang Ha Park, Hyeon Ji Yeo, Nam Su Kim, Ye Eun Park, Soo-Yun Park, Jae Kwang Kim, Sang Un Park
Rhododendron schlippenbachii Maxim. is a garden plant that is also used for natural medicines as a consequence of the biological activities of its diverse metabolites. We accordingly profiled two anthocyanins and 40 primary and secondary metabolites in the three different colored flowers. The major anthocyanins found in the flowers were cyanidins. The red flowers exhibited the highest accumulation of anthocyanins (1.02 ± 0.02 mg/g dry weight). Principal component analysis was applied to the GC‒TOFMS data...
April 4, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29615664/metabolomics-coupled-with-pathway-analysis-characterizes-metabolic-changes-in-response-to-bde-3-induced-reproductive-toxicity-in-mice
#7
Ziheng Wei, Jing Xi, Songyan Gao, Xinyue You, Na Li, Yiyi Cao, Liupeng Wang, Yang Luan, Xin Dong
Polybrominated diphenyl ethers (PBDEs) may affect male reproductive function. 4-bromodiphenyl ether (BDE-3), the photodegradation products of higher brominated PBDEs, is the most fundamental mono-BDE in environment but is less studied. The purpose of this study was to investigate the reproductive toxicity induced by BDE-3 and explore the mechanism by metabolomics approach. In this study, mice were treated intragastrically with BDE-3 for consecutive six weeks at the dosages of 0.0015, 1.5, 10 and 30 mg/kg...
April 3, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29600458/identification-of-tyrosine-and-nitrotyrosine-with-a-mixed-mode-solid-phase-extraction-cleanup-followed-by-liquid-chromatography-electrospray-time-of-flight-mass-spectrometry-in-plants
#8
Mounira Chaki, Beatriz Sánchez-Calvo, Alfonso Carreras, Raquel Valderrama, Juan C Begara-Morales, Francisco J Corpas, Juan B Barroso
In higher plants, there is a growing interest in the study of protein tyrosine nitration (NO2 Tyr) as well as the identification of in vivo nitrated proteins. Different methods have been developed for identifying nitrotyrosine in biological samples. However, these analyses are difficult because tyrosine nitration is a very low-abundance posttranslational protein modification (PTM) and the lack of efficient enrichment methods for detection. The identification and quantification of NO2 Tyr in proteins has represented a challenge for researchers...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29575899/sequential-hybrid-three-dimensional-gas-chromatography-with-accurate-mass-spectrometry-a-novel-tool-for-high-resolution-characterization-of-multicomponent-samples
#9
Dandan Yan, Yong Foo Wong, Simon P Whittock, Anthony Koutoulis, Robert A Shellie, Philip John Marriott
A novel sequential three-dimensional gas chromatography - high resolution time-of-flight mass spectrometry (3D GC-accTOFMS) approach for profiling secondary metabolites in complex plant extracts is described. This integrated system incorporates a non-polar first-dimension (1 Dnp ) separation step, prior to microfluidic heart-cut (H/C) of a targeted region(s) to a cryogenic trapping device, directly followed by rapid re-injection of trapped solute into a polar second-dimension (2 DPEG ) column for multidimensional separation (GCnp -GCPEG )...
March 26, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29572459/untargeted-metabolomics-reveals-a-new-mode-of-action-of-pretomanid-pa-824
#10
Rafael Baptista, David M Fazakerley, Manfred Beckmann, Les Baillie, Luis A J Mur
Pretomanid is a promising anti-tubercular drug currently at clinical phase III, but its mechanisms of action are currently unclear. This study aimed to: (i) reveal the metabolome of Mycobacterium smegmatis under pretomanid treatment; (ii) compare major sources of metabolite variation in bacteria treated with pretomanid treatment and other antibiotics; and (iii) to target metabolites responsible for the killing activity of pretomanid in mycobacteria. Untargeted high-resolution metabolite profiling was carried out using flow infusion electrospray ion high resolution mass spectrometry (FIE-HRMS) to identify and quantify metabolites...
March 23, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29570978/direct-detection-of-small-n-alkanes-at-sub-ppbv-level-by-photoelectron-induced-o2-cation-chemical-ionization-mass-spectrometry-at-kpa-pressure
#11
Yan Wang, Lei Hua, Qingyun Li, Jichun Jiang, Keyong Hou, Chenxin Wu, Haiyang Li
Direct mass spectrometric measurements of saturated hydrocarbons, especially small n-alkanes, remains a great challenge due to low basicity and lack of ionizable functional groups. In this work, a novel high-pressure photoelectron induced O2+ cation chemical ionization source (HPPI-OCI) at kPa based on a 10.6 eV krypton lamp was developed for time-of-flight mass spectrometer (TOFMS). High-intensity O2+ reactant ions were generated by photoelectron ionization of air molecules in the double electric field ionization region...
March 23, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29526271/profiling-the-scent-of-weathered-training-aids-for-blood-detection-dogs
#12
Baree Chilcote, LaTara Rust, Katie D Nizio, Shari L Forbes
At outdoor crime scenes, cadaver-detection and blood-detection dogs may be tasked with locating blood that is days, weeks or months old. Although it is known that the odour profile of blood will change during this time, it is currently unknown how the profile changes when exposed to the environment. Such variables must be studied in order to understand when the odour profile is no longer detectable by the scent-detection dogs and other crime scene tools should be implemented. In this study, blood was deposited onto concrete and varnished wood surfaces and weathered in an outdoor environment over a three-month period...
March 2018: Science & Justice: Journal of the Forensic Science Society
https://www.readbyqxmd.com/read/29520912/laser-ablation-synthesis-of-arsenic-phosphide-as-m-p-n-clusters-from-as-p-mixtures-laser-desorption-ionisation-with-quadrupole-ion-trap-time-of-flight-mass-spectrometry-the-mass-spectrometer-as-a-synthesizer
#13
Pavel Kubáček, Lubomír Prokeš, Annapurna Pamreddy, Eladia María Peña-Méndez, José Elias Conde, Milan Alberti, Josef Havel
RATIONALE: Only a few arsenic phosphides are known. A high potential for the generation of new compounds is offered by Laser Ablation Synthesis (LAS) and when Laser Desorption Ionization (LDI) is coupled with simultaneous Time-Of-Flight Mass Spectrometry (TOFMS), immediate identification of the clusters can be achieved. METHODS: LAS was used for the generation of arsenic phosphides via laser ablation of phosphorus-arsenic mixtures while quadrupole ion trap time-of-flight mass spectrometry (QIT-TOFMS) was used to acquire the mass spectra...
May 30, 2018: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/29520903/investigation-of-ultrahigh-performance-liquid-chromatography-travelling-wave-ion-mobility-time-of-flight-mass-spectrometry-for-fast-profiling-of-fatty-acids-in-the-high-arctic-sea-surface-microlayer
#14
Farshid Mashayekhy Rad, Caroline Leck, Leopold L Ilag, Ulrika Nilsson
RATIONALE: Fatty acids are enriched in the ocean surface microlayer (SML) and have as a consequence been detected worldwide in sea spray aerosols. In searching for a relationship between the properties of the atmospheric aerosol and its ability to form cloud condensation nuclei and to promote cloud droplet formation over remote marine areas, the role of surface active fatty acids sourced from the SML is of interest to be investigated. Here we present a fast method for profiling of major fatty acids in SML samples collected in the high Arctic (89°N, 1°W) in the summer of 2001...
June 30, 2018: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/29505166/improved-detection-sensitivity-of-elements-in-solids-via-laser-postionization-in-laser-desorption-time-of-flight-mass-spectrometry
#15
Zhibin Yin, Le Hang, Rong Liu, Wei Hang, Benli Huang
A newly constructed laser desorption (532 nm, 5 ns) and laser postionization (266 nm, 5 ns) time-of-flight mass spectrometer (LD-LPI-TOFMS) has been applied for improving the detection sensitivity of elements in solid samples. This method affords to acquire the information of the elemental impurities in solid standards as well as limit of detection (LOD) down to 10-8  g/g for some elements. Neutral atoms of solids are generated by low-irradiance laser desorption (< 108  W/cm2 ), followed by high-irradiance laser postionization (~ 109  W/cm2 ) of the desorbed atoms, facilitating to decouple the desorption and ionization processes in spatial and temporal domain...
May 2018: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/29501929/analysis-of-volatile-compounds-in-chinese-dry-cured-hams-by-comprehensive-two-dimensional-gas-chromatography-with-high-resolution-time-of-flight-mass-spectrometry
#16
Wenli Wang, Xi Feng, Danni Zhang, Bei Li, Baoguo Sun, Hongyu Tian, Yuan Liu
A microwave assisted extraction method coupled with solvent assisted flavor evaporation (MAE-SAFE) was used to extract the volatiles from three-selected Chinese dry-cured hams (Jinhua ham, Xuanwei ham and Rugao ham). Extracts were analyzed by comprehensive two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry (GC × GC/HR-TOFMS), gas chromatography-mass spectrometry (GC-MS), respectively. A total 165 volatile compounds were identified by GC × GC/HR-TOFMS while only 50 compounds were identified by GC-MS...
June 2018: Meat Science
https://www.readbyqxmd.com/read/29496335/the-reduction-of-l-cystine-to-l-cysteine-in-the-supernatant-of-a549-cell-culture-causes-imipenem-inactivation
#17
Hiromu Takemura, Shigemi Terakubo, Ninyo Okamura, Hideki Nakashima
In the course of measuring the intracellular antibacterial activity of antibiotics using a human alveolar epithelial cell line A549, we discovered that the antimicrobial activity of several carbapenems (CPs) decreased in the supernatant of the cells cultured with fetal calf serum (FCS)-free RPMI1640 medium (RPMI). Further investigation revealed A549 culture supernatant inhibited the antibacterial activity of CPs but did not inactivate other types of antibiotics. CE-TOFMS and LC-TOFMS metabolomics analysis of the supernatant revealed the presence of l-cysteine (Cys), which is not an original component in RPMI...
May 2018: Journal of Infection and Chemotherapy: Official Journal of the Japan Society of Chemotherapy
https://www.readbyqxmd.com/read/29495842/a-new-time-of-flight-mass-spectrometer-for-absolute-dissociative-electron-attachment-cross-section-measurements-in-gas-phase
#18
Dipayan Chakraborty, Pamir Nag, Dhananjay Nandi
A new time of flight mass spectrometer (TOFMS) has been developed to study the absolute dissociative electron attachment (DEA) cross section using a relative flow technique of a wide variety of molecules in gas phase, ranging from simple diatomic to complex biomolecules. Unlike the Wiley-McLaren type TOFMS, here the total ion collection condition has been achieved without compromising the mass resolution by introducing a field free drift region after the lensing arrangement. The field free interaction region is provided for low energy electron molecule collision studies...
February 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29473751/hexaphenolic-rigid-cages-prepared-by-self-organization-of-c-3-v-tridentates
#19
Hajime Abe, Daisuke Hashikawa, Takaya Minami, Kohei Ohtani, Kentaro Masuda, Shinya Matsumoto, Masahiko Inouye
Coordination cages were composed by self-organization of rigid C3 v -symmetric heptaarene tridentates and Pd(II) precursors. The heptaarene framework involves one mesitylene, three phenol, and three pyridine moieties, which were connected by Suzuki coupling reactions. The treatment of the tridentates with Pd(dppp)(OTf)2 or Pd(en)(NO3 )2 in a 2:3 molar ratio furnished coordination cages, which was ascertained by crystallography, 1 H NMR and DOSY measurements, and ESI-TOFMS and UV-vis spectra. The cages have six phenolic hydroxy groups inside and were expected to incorporate hydrogen-bonding guest molecules such as saccharides...
March 16, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29422017/metabolomic-profiling-identifies-distinct-phenotypes-for-ass1-positive-and-negative-gbm
#20
Lina Mörén, Richard Perryman, Tim Crook, Julia K Langer, Kevin Oneill, Nelofer Syed, Henrik Antti
BACKGROUND: Tumour cells have a high demand for arginine. However, a subset of glioblastomas has a defect in the arginine biosynthetic pathway due to epigenetic silencing of the rate limiting enzyme argininosuccinate synthetase (ASS1). These tumours are auxotrophic for arginine and susceptible to the arginine degrading enzyme, pegylated arginine deiminase (ADI-PEG20). Moreover, ASS1 deficient GBM have a worse prognosis compared to ASS1 positive tumours. Since altered tumour metabolism is one of the hallmarks of cancer we were interested to determine if these two subtypes exhibited different metabolic profiles that could allow for their non-invasive detection as well as unveil additional novel therapeutic opportunities...
February 8, 2018: BMC Cancer
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