Search results for "Analytical"
showing 10 items of 9586 documents
Chemical Composition of the Essential Oil of the New Cultivars of Lavandula angustifolia Mill. Bred in Ukraine
2021
Lavender, otherwise known as Lavandula angustifolia Mill., is widely used in landscaping, and its oil is a valuable raw material used in many industries. Therefore, new varieties of this plant are bred. The essential oil composition obtained from fresh flowers of thirteen new Ukrainian cultivars of L. angustifolia were analysed by GC-MS, and eighty-two components were identified. Linalool and linalyl acetate were principal constituents of all of the samples, and ranged from 11.4% to 46.7% and 7.4% to 44.2%, respectively. None of the studied samples fulfilled the requirements of Ph. Eur. and ISO 3515:2002. The main reason was a high content of α-terpineol (0.5–4.5%) and/or terpinene-4-ol (1.…
Guided Wave Techniques for Damage Detection in Composite Aerospace Structures
2018
Composite materials make up an increasing portion of today’s aerospace structures (see, e.g. Boeing 787 and Airbus 380). These aircrafts’ fuselage, for example, is composed of a laminated composite skin connected to composite stringers and C-frames. Of primary importance is the detection of damage in these built-up structures, whether caused by the manufacturing process or in service (e.g. impacts). A related issue is the characterization of the composite (visco)elastic mechanical properties, that can also be related to the quantification of potential damage. Guided elastic waves propagating in the ~100s kHz regime lend themselves to provide the necessary sensitivity to these two conditions…
Minimum detection limits and applications of proton and helium induced X-ray emission using transition-edge sensor array
2017
Abstract We have determined minimum detection limits, MDLs, for elements 14 ⩽ Z ⩽ 86 using a transition-edge sensor array, TES array, and as a comparison using an Amptek X-123SDD silicon drift detector, SDD. This was done using a 3 MeV proton beam and a 5.1 MeV helium beam. MDLs were determined for a thin film sample on top of C substrate, and for a bulk sample containing mostly Al. Due to the higher peak-to-background ratio, lower detection limits were obtainable using the TES array for most of the elements. However, for elements 30 ⩽ Z ⩽ 45 the performance of the TES array was not as good as the SDD performance. This is due to the limitations of the TES used at energies >10 keV. The great…
From the forest to the plate – Hemicelluloses, galactoglucomannan, glucuronoxylan, and phenolic-rich extracts from unconventional sources as function…
2021
This study aimed to characterise pressurised hot water (PHW) extracts from nonconventional sources of functional carbohydrates and phenolic compounds in terms of antioxidant capacity, antiviral activity, toxicity, and human erythrocytes’ protection antidiabetic potential. PHW extracts of Norway spruce bark (E1 + E2) and Birch sawdust (E3 + E4) contained mostly galactoglucomannan and glucuronoxylan. In contrast, samples E5 to E9 PHW extracted from Norway spruce, and Scots pine bark are rich sources of phenolic compounds. Overall, phenolic-rich extracts presented the highest inhibition of α-amylase and α-glucosidase and protection against stable non-enveloped enteroviruses. Additionally, all …
Scalable (Enantioselective) Syntheses of Novel 3-Methylated Analogs of Pazinaclone, (S)-PD172938 and Related Biologically Relevant Isoindolinones
2022
Herein, we report the application of an efficient and practical K2CO3 promoted cascade reaction of 2-acetylbenzonitrile in the synthesis of novel 3-methylated analogs of Pazinaclone and PD172938, belonging to isoindolinones heterocyclic class bearing a tetrasubstituted stereocenter. Organocatalytic asymmetric synthesis of the key intermediate and its transformation into highly enantioenriched 3-methylated analog of (S)-PD172938 was also developed. These achievements can be of particular interest also for medicinal chemistry, since the methyl group is a very useful structural modification in the rational design of new and more effective bioactive compounds.
The Role Played by Ionic Liquids in Carbohydrates Conversion into 5-Hydroxymethylfurfural: A Recent Overview
2022
Obtaining industrially relevant products from abundant, cheap, renewable, and low-impacting sources such as lignocellulosic biomass, is a key step in reducing consumption of raw fossil materials and, consequently, the environmental footprint of such processes. In this regard, a molecule that is similar to 5-hydroxymethylfurfural (5-HMF) plays a pivotal role, since it can be produced from lignocellulosic biomass and gives synthetic access to a broad range of industrially important products and polymers. Recently, ionic liquids (ILs) have emerged as suitable solvents for the conversion of biomass and carbohydrates into 5-HMF. Herein, we provide a bird’s-eye view on recent achievements about t…
Single hollow fiber SLM extraction of polyamines followed by tosyl chloride derivatization and HPLC determination
2007
Determination of polyamines in biological fluids possesses medical diagnostic relevance. Despite the vast panel of analytical methods developed for polyamines they are not applied in routine clinical usage, mainly due to the time and labor consuming sample preparation step and complicated derivatization procedures. Thus, new simpler methods are needed. This paper describes a single hollow fiber SLM extraction method of polyamines followed by simple pre-column derivatization with tosyl chloride and HPLC-UV analysis. The influence of different parameters such as the extraction time, organic phase composition, acceptor pH, donor pH, acceptor volume, donor volume and stirring speed on the trans…
Influence of temperature on mass transfer in an incomplete trapping single hollow fibre supported liquid membrane extraction of triazole fungicides.
2008
The influence of temperature in a single hollow fibre supported liquid membrane extraction of triazole fungicides with a stagnant acceptor phase was investigated. The mass transfer parameters such as diffusion coefficient, flux and apparent viscosity were determined at temperature ranging from 278 K to 313 K. Increase in temperature led to an increase in diffusion coefficient and flux. The apparent viscosity also decreased with an increase in temperature. The degree of trapping in the acceptor phase influenced the mass transfer at higher temperature. At lower temperature, the transport of analytes from the donor solution through the donor-membrane interface and through the membrane mainly a…
Modelling molecular iodine emissions in a coastal marine environment: The link to new particle formation
2006
International audience; A model of iodine chemistry in the marine boundary layer (MBL) has been used to investigate the impact of daytime coastal emissions of molecular iodine (I2). The model contains a full treatment of gas-phase iodine chemistry, combined with a description of the nucleation and growth, by condensation and coagulation, of iodine oxide nano-particles. In-situ measurements of coastal emissions of I2 made by the broadband cavity ring-down spectroscopy (BBCRDS) and inductively coupled plasma-mass spectrometry (ICP/MS) techniques are presented and compared to long path differential optical absorption spectroscopy (DOAS) observations of I2 at Mace Head, Ireland. Simultaneous me…
Switching from Aromatase Inhibitors to Dual Targeting Flavonoid-Based Compounds for Breast Cancer Treatment
2023
Despite the significant outcomes attained by scientific research, breast cancer (BC) still represents the second leading cause of death in women. Estrogen receptor-positive (ER+) BC accounts for the majority of diagnosed BCs, highlighting the disruption of estrogenic signalling as target for first-line treatment. This goal is presently pursued by inhibiting aromatase (AR) enzyme or by modulating Estrogen Receptor (ER) α. An appealing strategy for fighting BC and reducing side effects and resistance issues may lie in the design of multifunctional compounds able to simultaneously target AR and ER. In this paper, previously reported flavonoid-related potent AR inhibitors were suitably modified…