2,755 research outputs found
Unusual cytotoxic sulfated cadinene-type sesquiterpene glycosides from cottonseed (Gossypium hirsutum).
Two new sulfated cadinene-type sesquiterpene glycosides, 13-hydroxy-7-O-(60-O-sulfate-b-D-glucopyranosyl)-desoxyhemigossypol (1) and 13,15-dihydroxy-7-O-(60-O-sulfate-b-D-glucopyranosyl)-desoxyhemigossypol (2), have been isolated from whole cottonseed (Gossypium hirsutum). Their structures,
which possess an unusual 6-O-sulfate-glucopyranosyl moiety, were determined through the interpretation of 2D NMR spectral data and H/D exchange ESI-MS experiments. Compounds 1 and 2 were screened for their toxicity on Jurkat cells. Both compounds inhibited cellular proliferation with IC50 values of 8.1 and 4.2 mg, respectively
On sample preparation methods for fermented beverage VOCs profiling by GCxGC-TOFMS
Introduction
Aromas and tastes have crucial influences on the quality of fermented beverages. The determination of aromatic compounds requires global non-targeted profiling of the volatile organic compounds (VOCs) in the beverages. However, experimental VOC profiling result depends on the chosen VOC collection method.
Objectives
This study aims to observe the impact of using different sample preparation techniques [dynamic headspace (DHS), vortex-assisted liquid–liquid microextraction (VALLME), multiple stir bar sorptive extraction (mSBSE), solid phase extraction (SPE), and solid phase micro-extraction (SPME)] to figure out the most suitable sample preparation protocol for profiling the VOCs from fermented beverages.
Methods
Five common sample preparation methods were studied with beer, cider, red wine, and white wine samples. After the sample preparation, collected VOCs were analyzed by two-dimensional gas chromatography coupled with time of flight mass spectrometry (GCxGC-TOFMS).
Results
GCxGC oven parameters can be optimized with the Box–Behnken surface response model and response measure on peak dispersion. Due to the unavoidable column and detector saturation during metabolomic analysis, errors may happen during mass spectrum construction. Profiling results obtained with different sample preparation methods show considerable variance. Common findings occupy a small fraction of total annotated VOCs. For known fermentative aromas, best coverage can be reached by using SPME together with SPE for beer, and VALLME for wine and cider.
Conclusions
GCxGC-TOFMS is a promising tool for non-targeted profiling on VOCs from fermented beverages. However, a proper data processing protocol is lacking for metabolomic analysis. Each sample preparation method has a specific profiling spectrum on VOC profiling. The coverage of the VOC metabolome can be improved by combining complementary methods
Memory effect in melting behaviour, crystallization kinetics and morphology of poly(propylene terephthalate)
Crystallization kinetics and melting behaviour of poly(propylene terephthalate) (PPT) were investigated by means of differential scanning calorimetry and hot-stage optical microscopy. Isothermal crystallization kinetics was analysed according to the Avrami treatment. The effects of temperature and duration of melting on the overall rate of isothermal crystallization were studied: the rate was found to decrease with increasing melting temperature and melting time. This result was discussed on the basis of the gradual destruction of predetermined athermal nuclei. Values of the Avrami exponent close to 3 were obtained, regardless of the adopted thermal treatment and the crystallization temperature, Tc, in agreement with a crystallization process originating from predetermined nuclei and characterized by three-dimensional spherulitic growth. As a matter of fact, spacefilling spherulites were observed by optical microscopy at all Tc's, independent of the applied thermal treatments. For each of them, the rate of crystallization became lower as Tc increased, as usual at low undercooling where the crystallization process is controlled by nucleation. The observed multiple endotherms, which are commonly displayed by polyesters, were influenced by Tc and ascribed to melting and recrystallization processes. Linear and non-linear treatments were applied in order to estimate the equilibrium melting temperature for PPT, by using the corrected melting temperatures. The non-linear estimation yielded an about 33°C higher value with respect to the one obtained by means of the linear approach. Through the analysis of secondary nucleation theory, the classical II→III transition was found to occur at a temperature of 194°C. The average work of chain folding for nucleation was determined to be c. 5.2 kcal/mol. The heat of fusion was correlated to the specific heat increment for samples with different degree of crystallinity and the results were interpreted on the basis of the existence of an interphase, whose amount was found to depend on the thermal treatment the polymer was subjected to
Estimate of the impact of background particles on the X-Ray Microcalorimeter Spectrometer on IXO
We present the results of a study on the impact of particles of galactic
(GCR) and solar origin for the X-ray Microcalorimeter Spectrometer (XMS) aboard
an astronomical satellite flying in an orbit at the second Lagrangian point
(L2). The detailed configuration presented in this paper is the one adopted for
the International X-Ray Observatory (IXO) study, however the derived estimates
can be considered a conservative limit for ATHENA, that is the IXO redefined
mission proposed to ESA. This work is aimed at the estimate of the residual
background level expected on the focal plane detector during the mission
lifetime, a crucial information in the development of any instrumental
configuration that optimizes the XMS scientific performances. We used the
Geant4 toolkit, a Monte Carlo based simulator, to investigate the rejection
efficiency of the anticoincidence system and assess the residual background on
the detector.Comment: 18 pages, 9 figure
EASL Clinical Practice Guideline : Occupational liver diseases
A variety of chemicals have been linked to occupational liver diseases, including several solvents and mixtures thereof, pesticides, and metals. Workplace exposures have been associated with virtually the entire spectrum of acute and chronic liver diseases. However, their prevalence is inadequately quantified and their epidemiology limited. Occupational liver diseases may result from high accidental or from prolonged lower level exposures. Whereas the former is uncommon and easily recognised, the latter are relatively more frequent but often overlooked because they may display normal values of conventional markers, have an insidious onset and be asymptomatic or be obfuscated and confounded by concurrent conditions. In addition, specific tests of toxicity are not available, histopathology may not be revealing and the assessment of internal dose of chemicals is usually not decisive. Given these circumstances, the diagnosis of these liver disorders is challenging, one of exclusion and often requires an interdisciplinary approach. These recommendations offer a classification of the type of liver injuries associated with occupational exposures \u2013 based in part on the criteria for drug-induced liver injury \u2013 a grading of their severity, and the diagnostic and preventive criteria for chemically induced occupational liver disease
Long-term effects of mineral precipitation on process performance, granules' morphology and microbial community in anammox granular sludge
Data on the proximate composition, bioactive compounds, physicochemical and functional properties of a collection of faba beans (Vicia faba L.) and lentils (Lens culinaris Medik.)
This dataset is referred to a collection of 41 faba bean (Vicia faba L.) and 15 lentil (Lens culinaris Medik.) accessions from the ex situ repository of the Institute of Biosciences and Bioresources of the Italian National Research Council (CNR-IBBR). All the accessions were grown at the experimental farm “P. Martucci” of the University of Bari “Aldo Moro” (41°01′22.1′′ N 16°54′21.0′′ E) during the growing season 2017–2018, according to a randomized block design with two replicates, each constituted by 10 individual plants. The dataset reports raw and elaborated analytical data determined on the flour produced from individual accessions, concerning proximate composition, bioactive compounds, antioxidant activity, fatty acid composition, and physicochemical and functional properties. Elaborated data might be used to understand the compositional variability within the species and, together with raw data, to highlight peculiar accessions characterized by valuable nutritional and/or technological attitude useful in research institutions and food industries. Furthermore, the data can be used for genetic studies aimed at identifying genomic regions underlying nutritional and technological traits
Fibroblasts to keratinocytes redox signaling: The possible role of ROS in psoriatic plaque formation
Although the role of reactive oxygen species-mediated (ROS-mediated) signalling in physiologic and pathologic skin conditions has been proven, no data exist on the skin cells ROS-mediated communication. Primary fibroblasts were obtained from lesional and non-lesional skin of psoriatic patients. ROS, superoxide anion, calcium and nitric oxide levels and lipoperoxidation markers and total antioxidant content were measured in fibroblasts. NADPH oxidase activity and NOX1, 2 and 4 expressions were assayed and NOX4 silencing was performed. Fibroblasts and healthy keratinocytes co-culture was performed. MAPK pathways activation was studied in fibroblasts and in co-cultured healthy keratinocytes. Increased intracellular calcium, •NO and ROS levels as well as an enhanced NADPH oxidase 4 (NOX4)–mediated extracellular ROS release was shown in lesional psoriatic vs. control fibroblasts. Upon co-culture with lesional fibroblasts, keratinocytes showed p38 and ERK MAPKs pathways activation, ROS, Ca2+ and •NO increase and cell cycle acceleration. Notably, NOX4 knockdown significantly reduced the observed effects of lesional fibroblasts on keratinocyte cell cycle progression. Co-culture with non-lesional psoriatic and control fibroblasts induced slight cell cycle acceleration, but notable intracellular ROS accumulation and ERK MAPK activation in keratinocytes. Collectively, our data demonstrate that NOX4 expressed in dermal fibroblasts is essential for the redox paracrine regulation of epidermal keratinocytes proliferation
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