6,760 research outputs found
On the bar pattern speed determination of NGC 3367
An important dynamic parameter of barred galaxies is the bar pattern speed.
Among several methods that are used for the determination of the pattern speed
the Tremaine-Weinberg method has the advantage of model independency and
accuracy. In this work we apply the method to a simulated bar including gas
dynamics and study the effect of 2D spectroscopy data quality on robustness of
the method. We added a white noise and a Gaussian random field to the data and
measured the corresponding errors in the pattern speed. We found that a signal
to noise ratio in surface density ~5 introduces errors of ~20% for the Gaussian
noise, while for the white noise the corresponding errors reach ~50%. At the
same time the velocity field is less sensitive to contamination. On the basis
of the performed study we applied the method to the NGC 3367 spiral galaxy
using H{\alpha} Fabry-Perot interferometry data. We found for the pattern speed
43 \pm 6 km/s/kpc for this galaxy.Comment: Accepted for publication in ApJ. 16 pages, 16 figure
A design framework for enabling sustainability in the clothing sector
This article discusses general strategies to enable environmental sustainability within the clothing sector, providing a framework for decision makers involved in the development of programs and policies for this sector. It initially revises the environmental impact of the clothing system and determines its key environmental sustainability priorities. The framework involves five evolutionary strategies for enabling sustainable consumption and production: 1) environmental improvement of flows throughout the supply chain; 2) environmental redesign of existing clothes; 3) design of new clothes intrinsically more sustainable; 4) design of cloth-service systems and 5) promoting life styles towards sufficient consumption. The practical implications of each strategy is analysed based on correspondent ex-post-facto case studies identified in Brazil, using data collected through literature review and desktop research
Extraction of silymarin compounds from milk thistle (Silybum marianum) seed using hot, liquid water as the solvent
High-value specialty chemicals are usually obtained from natural products by extracting with generally regarded as safe (GRAS) solvents. Because organic solvents are quite often used, high operating and disposal costs occur. When compared to traditional solvents, water is an interesting alternative because of its low operating and disposal costs. Milk thistle contains compounds (taxifolin, silychristin, silydianin, silybinin A, and silybinin B) that display hepatoxic protection properties. This paper examines the batch extraction of silymarin compounds from milk thistle seed meal in 50°C, 70°C, 85°C and 100°C water as a function of time. For taxifolin, silychristin, silybinin A, and silybinin B, extraction with 100°C water resulted in the highest yields. After 210 min of extraction at 100°C, the yield of taxifolin was 1.2 mg/g of seed while the yields of silychristin, silybinin A, and silybinin B were 5.0, 1.8 and 3.3 mg/g of seed, respectively. The ratios of the extracted compounds, and particularly the ratios at long extraction times, showed that the more polar compounds (taxifolin and silychristin) were preferentially extracted at 85°C, while the less polar silybinin was preferentially extracted at 100°C
- …