the volatile components of citrus aurantium l. flowers were characterized by gc-ms with two different extraction techniques, hydrodistillation (hd) and ultrasonic-assisted headspace solid phase microextraction (ua-hs-spme). in the spme method, the volatile components of the samples, irradiated by ultrasonic radiation, were collected on a polydimethyl siloxane (pdms) commercial fiber as well as ...

background and objectives: colocynthin is the major active secondary metabolite of colocynth, citrullus colocynthis (l.) schrad, which has been used in traditional and ethno medicine of many countries.  it could be considered as an active marker for quality control of colocynth and its herbal products. analysis and standardization of colocynth and its herbal preparations are a critical issue fo...

Heavy organics deposition is a common problem in oil industry, especially in oil production, transportation and processing. Wax or solid paraffin series are examples of heavy organics that deposit. Precipitation and crystallization of wax causes major difficulties in different processes. Based on multi-solid theory, a basic model is modified in this paper for wax precipitation in different oils...

The organic deposition particularly asphaltenes has many detrimental effects on the oil industries, such as plugging in pipelines, wellbore and facilities and subsequently, considerable reduction in well productivity.Asphaltenes are the most polar fractions, which they have been dispersed as colloidal clusters in crude oil. The accumulation of these clusters lead to the flocculation of colloids...

So far, no research has been focused on the determination of organomercuries in sewage sludge. Here, an ultrasonic extraction method for the rapid determination of methylmercury (MeHg) and ethylmercury (EtHg) in sewage sludge after ultrasound-assisted extraction is proposed. Using TMA (tetramethylammonium hydroxide) as the extractant with 3.0 g copper powder, ultrasonic extraction for 30 min at...

After different rolling conditions, four 7055 aluminum alloy samples with precipitation sizes were measured by scanning electron microscope, transmission microscope and laser ultrasonic. The attenuation coefficients of ultrasound ultrasonic calculated in the time domain, frequency domain wavelet denoising, respectively. relationship between precipitate size coefficient was established. results ...