34 research outputs found
Effects of discrete energy and helicity conservation in numerical simulations of helical turbulence
Helicity is the scalar product between velocity and vorticity and, just like
energy, its integral is an in-viscid invariant of the three-dimensional
incompressible Navier-Stokes equations. However, space-and time-discretization
methods typically corrupt this property, leading to violation of the inviscid
conservation principles. This work investigates the discrete helicity
conservation properties of spectral and finite-differencing methods, in
relation to the form employed for the convective term. Effects due to
Runge-Kutta time-advancement schemes are also taken into consideration in the
analysis. The theoretical results are proved against inviscid numerical
simulations, while a scale-dependent analysis of energy, helicity and their
non-linear transfers is performed to further characterize the discretization
errors of the different forms in forced helical turbulence simulations
High-performance liquid chromatographyâmass spectrometry profiling of phenolic compounds for evaluation of olive oil bitterness and pungency
Bitterness and pungency are important parameters for olive oil quality. Therefore, two instrumental methods for evaluation of these taste attributes were developed. The first one is based on the photometric measurement of total phenolic compounds content, whereas the second one is based on the semiquantitative evaluation of hydrophilic compounds by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Evaluation of total phenolic compounds content was performed by a modified method for the determination of the K225 value using a more specific detection based on the pH value dependency of absorbance coefficients of phenols at λ = 274 nm. The latter method was not suitable for correct prediction, because no significant correlation between bitterness/pungency and total phenolic compounds content could be found. For the second method, areas of 25 peaks detected in 54 olive oil samples by a HPLC-MS profiling method were correlated with the bitterness and pungency by partial least-squares regression. Six compounds (oleuropein aglycon, ligstroside aglycon, decarboxymethyl oleuropein aglycon, decarboxymethyl ligstroside aglycon, elenolic acid, and elenolic acid methyl ester) show high correlations to bitterness and pungency. The computed model using these six compounds was able to predict bitterness and pungency of olive oil in the error margin of the sensory evaluation (±0.5) for most of the samples
Prevalence, clinical management and risks associated with acute faecal incontinence in the critical care setting: the FIRST questionnaire survey
Scar sarcoidosis on a finger mimicking a rapidly growing soft tissue tumour: a case report
Background: Scar sarcoidosis is a rare and uncommon but specific cutaneous manifestation of sarcoidosis. In general it arises in pre-existing scars deriving from mechanical traumas. As most surgeons dealing with scars might not be aware of cutaneous sarcoidosis and its different types of appearance the appropriate staging and treatment might be missed or at least delayed. To our knowledge this is the first case in literature of scar sarcoidosis on a finger. Case presentation: We present a case of a 33-year-old carpenter who developed scar sarcoidosis on his right index finger 4 years after the tendon of the long digital flexor got accidentally cut by an angle grinder. He was referred due to a swelling of the finger suspected to be a malignant soft tissue tumour. The circumference of the affected finger had almost doubled, adding up to 94 mm. Incision biopsy revealed typical noncaseating granulomas. Further investigation showed a systemic extent of the disease with involvement of the lung. A systemic treatment with oral steroids led to an almost full regression of the swelling with restoration of function and resolution of lung infiltrates. Conclusion: In case of a suspicious and/or progressive swelling a definite diagnosis should be achieved by biopsy within a short time to enable a proper treatment. If scar sarcoidosis is proven further investigation is necessary to exclude a systemical involvement. A surgical treatment of the swelling is not indicated.</p
Prevalence, clinical consequences and management of acute faecal incontinence with diarrhoea in the ICU: The FIRSTâą Observational Study
There are limited data on the incidence and management of acute faecal incontinence with diarrhoea in the ICU. The FIRSTâą Observational Study was undertaken to obtain data on clinical practices used in the ICU for the management of acute faecal incontinence with diarrhoea in Germany, UK, Spain and Italy. ICU-hospitalised patients â„18 years of age experiencing a second episode of acute faecal incontinence with diarrhoea in 24âh were recruited, and management practices of acute faecal incontinence with diarrhoea were recorded for up to 15 days. A total of 372 patients had complete data sets; the mean duration of study was 6.8 days. At baseline, 40% of patients experienced mild or moderate-to-severe skin excoriation, which increased to 63% in patients with acute faecal incontinence with diarrhoea lasting >15 days. At baseline, 27% of patients presented with a pressure ulcer, which increased to 37%, 45% and 49% at days 5, 10 and 15, respectively. Traditional methods (pads, sheets and tubes) were more commonly used compared to faecal management systems during days 1â4 (76% vs. 47% faecal management system), while the use of a faecal management system increased to 56% at days 5â9 and 61% at days 10â15. At baseline, only 26% of nurses were satisfied with traditional management methods compared to 69% with faecal management systems. For patients still experiencing acute faecal incontinence with diarrhoea after 15 days, 82% of nurses using a faecal management systems to manage acute faecal incontinence with diarrhoea were satisfied or very satisfied, compared to 37% using traditional methods. These results highlight that acute faecal incontinence with diarrhoea remains an important healthcare challenge in ICUs in Europe; skin breakdown and pressure ulcers remain common complications in patients with acute faecal incontinence with diarrhoea in the ICU
Quality evaluation of olive oil by statistical analysis of multicomponent stable isotope dilution assay data of aroma active compounds
An instrumental method for the evaluation of olive oil quality was developed. Twenty-one relevant aroma active compounds were quantified in 95 olive oil samples of different quality by headspace solid phase microextraction (HS-SPME) and dynamic headspace coupled to GC-MS. On the basis of these stable isotope dilution assay results, statistical evaluation by partial least-squares discriminant analysis (PLS-DA) was performed. Important variables were the odor activity values of ethyl isobutanoate, ethyl 2-methylbutanoate, 3-methylbutanol, butyric acid, E,E-2,4-decadienal, hexanoic acid, guaiacol, 2-phenylethanol, and the sum of the odor activity values of Z-3-hexenal, E-2-hexenal, Z-3-hexenyl acetate, and Z-3-hexenol. Classification performed with these variables predicted 88% of the olive oils? quality correctly. Additionally, the aroma compounds, which are characteristic for some off-flavors, were dissolved in refined plant oil. Sensory evaluation of these models demonstrated that the off-flavors rancid, fusty, and vinegary could be successfully simulated by a limited number of odorants
Lösungsstrategien zur Verminderung von EintrÀgen von urbanem Plastik in limnische Systeme - PLASTRAT - Synthesebericht
Der Einsatz von Plastik gehört zu den groĂen Errungenschaften unserer Zeit. Die Nutzung
von Plastik in unseren verschiedenen Lebensbereichen ermöglicht uns heute Vieles. Dabei
setzen wir Plastik oft ein, ohne dass uns dies bewusst ist. Wieviel âvirtuelles Plastikâ war
allein notwendig, um diesen Synthesebericht zu erstellen? Wieviel Plastik benötigen Sie
gerade, um diesen Synthesebericht zu lesen?
Wie so oft, so hat auch der Einsatz von Plastik zwei Seiten: den positiven Errungenschaften
stehen negative Auswirkungen gegenĂŒber, vor allem nach der Nutzung von Plastik. Im Fokus
stehen hierbei Fragestellungen der Toxikologie sowie der Abfallverwertung. Im Gegensatz
zu vielen anderen Stoffen, mit denen wir tĂ€glich in BerĂŒhrung sind, hat Plastik die Eigenschaft,
dass sich kleinste Partikel bilden. So ist es nicht verwunderlich, dass sich mittlerweile
in allen Umweltmedien Mikroplastikpartikel finden lassen.
Die Idee von PLASTRAT war es, in einem interdisziplinĂ€ren Team AnsĂ€tze fĂŒr die Verminderung
von EintrĂ€gen von Plastik in GewĂ€sser zu untersuchen. Dabei standen ĂŒber den
Ansatz der systemischen Risikoanalyse die unterschiedlichen Sektoren im Fokus, angefangen
von der Erzeugung, ĂŒber die Nutzung bis hin zu den Eintragspfaden und die toxikologische
Bewertung. Der Synthesebericht fasst die Ergebnisse von PLASTRAT zusammen.
Vor allem zeigt der Synthesebericht die groĂen Herausforderungen sowie LösungsansĂ€tze
zum Thema Mikroplastik auf. Dabei wird auch deutlich, dass wir bei vielen Fragestellungen
zum Umgang mit Plastik erst am Anfang stehen.
Die ersten Ideen zu PLASTRAT entstanden 2016. In den vergangenen fĂŒnf Jahren stand
das Thema Plastik im Fokus von Ăffentlichkeit und Presse. In dieser Zeit gab es bereits
wichtige VerÀnderungen beim Einsatz von Plastik bei diversen Produkten, beispielsweise
durch die Substitution durch alternative Materialien. Dies zeigt deutlich, dass eine BewusstseinsverÀnderung
stattgefunden hat, die sich sicherlich in der Zukunft fortsetzten wird.
Die Arbeiten und Diskussionen im Projektteam von PLASTRAT waren spannend. In vielen
Projektbesprechungen wurde an den Forschungsfragestellungen gearbeitet und nach Lösungen
gesucht. Es gab einen intensiven persönlichen Austausch mit allen am Projekt beteiligten
Personen, so dass uns die seit 2020 geltenden EinschrÀnkungen durch die
Corona-Pandemie nicht immer leichtgefallen sind.
Wir möchten uns bei allen bedanken, die bei PLASTRAT mitgewirkt haben. Allen Lesern
des Syntheseberichts wĂŒnschen wir viele Freude beim Lesen und hoffen, dass wir Ihnen
einen Impuls fĂŒr den zukĂŒnftigen Umgang mit (Mikro-)Plastik geben können
Benchmarking the in Vitro Toxicity and Chemical Composition of Plastic Consumer Products
Plastics are known sources of chemical exposure and few, prominent plastic-associated chemicals, such as bisphenol A and phthalates, have been thoroughly studied. However, a comprehensive characterization of the complex chemical mixtures present in plastics is missing. In this study, we benchmark plastic consumer products, covering eight major polymer types, according to their toxicological and chemical signatures using in vitro bioassays and nontarget high-resolution mass spectrometry. Most (74%) of the 34 plastic extracts contained chemicals triggering at least one end point, including baseline toxicity (62%), oxidative stress (41%), cytotoxicity (32%), estrogenicity (12%), and antiandrogenicity (27%). In total, we detected 1411 features, tentatively identified 260, including monomers, additives, and nonintentionally added substances, and prioritized 27 chemicals. Extracts of polyvinyl chloride (PVC) and polyurethane (PUR) induced the highest toxicity, whereas polyethylene terephthalate (PET) and high-density polyethylene (HDPE) caused no or low toxicity. High baseline toxicity was detected in all âbioplasticsâ made of polylactic acid (PLA). The toxicities of low-density polyethylene (LDPE), polystyrene (PS), and polypropylene (PP) varied. Our study demonstrates that consumer plastics contain compounds that are toxic in vitro but remain largely unidentified. Since the risk of unknown compounds cannot be assessed, this poses a challenge to manufacturers, public health authorities, and researchers alike. However, we also demonstrate that products not inducing toxicity are already on the market
Microplastic in Water and Sediments at the Confluence of the Elbe and Mulde Rivers in Germany
Accumulation of microplastics in aquatic environments is an issue of emerging concern. Initially, research focused on marine systems. However, recent studies also investigate the abundance of microplastics in freshwater environments. Rivers connect terrestrial with marine ecosystems and contribute a considerable share of macro- and microplastics to the oceans. A previous study found a large amount of micro-spheres in Dessau downstream the river mouth of the Mulde. Therefore, the objective of this research was to examine whether the Mulde river with its highly industrialized catchment contributes to the microplastic pollution of the Elbe. Sediment (Van Veen grab sampler) and water samples (filter cascade with the smallest mesh size 50 mu m and nets with the smallest mesh size 150 mu m) were taken from the Elbe river up- and downstream the confluence with the Mulde. After extensive sample preparation, we examined the samples under a digital microscope and determined polymer types by pyrolysis Gas Chromatography/Mass Spectrometry (pyr-GC-MS). The amount of primary microplastics increased in sediment and water samples just downstream the confluence. Those microplastics originate probably from the Mulde. We measured larger amounts and different shapes of microplastics in filter cascades that have a smaller mesh size compared to the nets