Search results for "Alchemy"

Optimal temporal resolution for detailed studies of cloud-enhanced sunlight (Overirradiance)

2013

Enhancement of sunlight by clouds can lead to irradiance peaks much exceeding the extraterrestrial levels - close to 2 suns near the Equator and at least 1.5 suns at latitudes of about 60°. Some extreme overirradiance events can last many minutes, but durations in the order of 1 second are also possible. The present paper reports the shortest bursts recorded in Southern Norway in the years 2012 and 2013. Our records of 10-millisecond resolution from 2012 show that the optimal instantaneous irradiance sampling interval is less than 0.15 s at the present test site, while the optimal averaging time is less than 0.13 s. We propose simple equations for deriving these times in an arbitrary geogra…

Extreme overirradiance events in Norway: 1.6 suns measured close to 60°N

2015

Abstract We report the most extreme overirradiance event of 1.6 kW/m 2 measured so far in Grimstad, southern Norway (latitude 58°20′), at altitude of only about 60 m a.s.l. Images of the sky conditions taken with a wide-dynamic-range camera suggest that this is not the ultimate value for our location, but that extremes as high as 1.7 kW/m 2 may be possible. The phenomenon was caused by strong forward scattering of sunlight within 3° around the solar disk in thin, broken altocumulus clouds. The normalized spectrum of sunlight during such extreme events is very similar to the normalized clear-sky spectrum measured at Air Mass 1.4 and irradiance of 1.0 kW/m 2 . We suggest that the values excee…

Fisiología de la secreción pancreática

2005

Three Spirostanol Glycosides from the Seeds of Hyoscyamus Niger L.

2006

Three steroidal glycosides of spirostane series have been isolated from the seeds of Hyoscyamus niger L.(Solanaceae). Their structures were determined on the basis of chemical evidence and extensive spectroscopic methods including one-dimensional, two-dimensional NMR and MS analysis. In the genus Hyoscyamus the given compounds have been found out for the first time.

GLYCOSIDES FROM LINARIA VULGARIS MILL

2008

A new flavonol glycoside, 5,4′-dimethylkaempferol 3-O-β-D-(6′′-α-Lrhamnopyranosyl) -glucopyranoside, together with three known compounds were isolated from the n-butanolic soluble fraction of underground and aerial parts of Linaria vulgaris Mill, collected on the territory of Moldova. The characterisation of these compounds was achieved by various chromatographic and spectroscopic methods (IR, UV, 13C-NMR, 1H-NMR and MS).

Cellulose Digestion in the Termite Gut

2005

Real-time optimization of the key filtration parameters in an AnMBR: Urban wastewater mono-digestion vs. co-digestion with domestic food waste

2018

[EN] This study describes a model-based method for real-time optimization of the key filtration parameters in a submerged anaerobic membrane bioreactor (AnMBR) treating urban wastewater (UWW) and UWW mixed with domestic food waste (FW). The method consists of an initial screening to find out adequate filtration conditions and a real-time optimizer applied to a periodically calibrated filtration model for minimizing the operating costs. The initial screening consists of two statistical analyses: (1) Morris screening method to identify the key filtration parameters; (2) Monte Carlo method to establish suitable initial control inputs values. The operating filtration cost after implementing the…

Determination of metal concentrations in certified plastic reference materials after small-size autoclave and microwave-assisted digestion followed w…

2017

Abstract The digestion methods for the determination of As, Cd, Cr, Pb, Sb, Sn and Zn concentrations in plastic samples using microwave-assisted digestion (MW-AD) and small-size autoclave digestion was developed. The certified polyethylene, polypropylene, polyvinyl chloride and acrylonitrile butadiene styrene certified reference materials were used in order to find digestion method working properly for several sample matrices. Efficiency of the digestion methods was evaluated by analyzing the residual carbon in digests by TOC analyzer. MW-AD using a mixture of 7 mL of HNO 3 and 3 mL of H 2 O 2 as a digestion solution resulted in excellent recoveries for As, Cd, Pb, Sb and Zn, and were in th…

On Kekulé’s insight

2012

Ciència i literatura. Ja han acabat les guerres entre les dues cultures?

2014

Des que l’alquímia va començar a desafiar l’autoritat de l’Església, l’estatus del coneixement científic especialitzat i de l’alta cultura, sempre relatiu, ha estat molt qu?estionat. Durant segles, els escriptors, com a adalils de la cultura, han atacat les pretensions de la ciència ridiculitzant els seus practicants bé com a éssers malvats, obsessius i fins i tot alienats o bé com a ximples i ineptes inventors els experiments dels quals fallen irremissiblement. Discutirem exemples d’ambdós models en el seu context històric. A les acaballes del segle XX apareix un nou gènere, conegut com a «literatura de laboratori» (lab-lit). Els científics s’hi veuen retratats no segons els estereotips si…