Search results for "EXTRACTION"

STUDIO DELLA BIODISTRIBUZIONE DI SOSTANZE BIOLOGICAMENTE ATTIVE IN ORGANISMI ACQUATICI

2022

Preparation of pH sensitive poly(vinilydenefluoride) porous membranes by grafting of acrylic acid assisted by supercritical carbon dioxide

2012

Free radical grafting of acrylic acid (AA) on poly(vinilydenefluoride) (PVDF) porous membranes was studied at 65°C using supercritical carbon dioxide (scCO 2) as a solvent and delivery agent. The process was initiated by the thermal decomposition of benzoylperoxide (BPO). Spectroscopic analyses confirmed the presence of poly(AA) chains linked to treated membranes. The mass fraction of grafted AA increased with grafting time and BPO concentration while it decreased when the density of the fluid phase was enhanced. A not-monotonic trend was obtained when the effect of the initial AA concentration was studied. The grafting process was accompanied by a reduction of the crystallinity of the PVDF…

Determination of 40 currently used pesticides in airborne particulate matter (PM 10) by microwave-assisted extraction and gas chromatography coupled …

2011

A confirmatory and sensitive procedure has been developed for the determination of 40 currently used pesticides (Cups) in airborne particulate matter (PM 10) at trace level. The proposed method includes extraction of PM 10-bound pesticides by microwave-assisted extraction (MAE) followed by a gel permeation chromatography (GPC) clean-up and determination by GC-MS/MS. The injection mode and the main parameters in MS/MS were optimized. The matrix effect was also evaluated. Recoveries ranged from 70 to 120% except for pyrimethanil and pirimicarb. The limit of quantification (LOQ) ranged from 1.32 to 39.47 pg m(-3), when air volumes of 760 m(3) were collected. The method was applied to 38 sample…

Platelet-rich plasma (PRP) in dental and oral surgery: from the wound healing to bone regeneration

2013

Platelet-rich plasma (PRP) is a new approach to tissue regeneration and it is becoming a valuable adjunct to promote healing in many procedures in dental and oral surgery, especially in aging patients. PRP derives from the centrifugation of the patient's own blood and it contains growth factors that influence wound healing, thereby playing an important role in tissue repairing mechanisms. The use of PRP in surgical practice could have beneficial outcomes, reducing bleeding and enhancing soft tissue healing and bone regeneration. Studies conducted on humans have yielded promising results regarding the application of PRP to many dental and oral surgical procedures (i.e. tooth extractions, per…

Influence of polymer packaging on the aroma of strawberry syrup

2001

International audience

Active-fixation coronary sinus pacing lead extraction: A hybrid approach

2012

Cardiac resynchronization therapy (CRT) can be considered as the standard treatment for patients suffering from heart failure (NYHA III–IV), severely reduced left ventricular (LV) function, and wide QRS complexes. Over the past years, the lead systems used to stimulate the left ventricle have evolved technically from epicardial approaches to a transvenous access accompanied by a significant reduction of procedure-related complication rates [1]. However, even today, LV dislodgement rates ranging 5–10% and the instability of thresholds over time remain the greatest challenges with transvenous LV leads in CRT. Therefore, a special LV lead utilizing active fixation (the Attain StarFix® active f…

A molecular approach to remove lead from drinking water

2005

Abstract Corrosion of lead-containing plumbings is responsible for significant contamination of tap water, which can reach several hundreds of micrograms per liter. According to a decision of the European Council applicable in 2013, the maximal lead level in tap water should not exceed 10 μg l −1 . A new concept has been explored that relies on solid-phase extraction by covalent attachment of a lead-selective macrocyclic sequestering agent onto the surface of silica gel. An N -carbamoylmethyl substituted 1,4,8,11-tetraazacyclotetradecane (cyclam) derivative was shown to exhibit favorable protonation properties together with an almost 10 6 -fold selectivity for lead over calcium. Structural …

On-fibre solid-phase microextraction coupled to conventional liquid chromatography versus in-tube solid-phase microextraction coupled to capillary li…

2006

This paper compares the advantages and disadvantages of two different configurations for the extraction of triazines from water samples: (1) on-fibre solid-phase microextraction (SPME) coupled to conventional liquid chromatography (LC); and (2) in-tube SPME coupled to capillary LC. In-tube SPME has been effected either with a packed column or with an open capillary column. A critical evaluation of the main parameters affecting the performance of each method has been carried out in order to select the most suitable approach according to the requirements of the analysis. In the on-fibre SPME configuration the fibre coating was polydimethylsiloxane (PDMS)-divinylbenzene (DVB). The limits of de…

Which factors influence orthodontists in their decision to extract? A questionnaire survey

2019

Background To evaluate the relative influence of different criteria in the choice between extraction and nonextraction treatment in current orthodontics, and to assess how the percentage of extractions has evolved over time. Material and methods Pre-treatment records (panoramic radiograph, lateral cephalogram, study casts and photographs) of fourteen cases in permanent dentition (adult or adolescent) with class I molar relationship and moderate anterior crowding were evaluated by 28 orthodontists. For each case, each orthodontist filled out a questionnaire reporting his treatment plan proposal (extraction or nonextraction) and the importance of specific parameters in his decision-making pro…

Pyrolysis-GC-MS and CuO-oxidation-HPLC in the characterization of HMMs from sediments and surface waters downstream of a pulp mill

1998

Abstract High molecular mass fractions of lignin and humic compounds in sediments and waters downstream of a pulp mill were characterized applying pyrolysis-gas chromatography-mass spectrometry. The results were compared to those obtained using reversed phase HPLC on the cupric oxide oxidation products. The chromatographic data of both pyrolysis and cupric oxide oxidation were also subjected to the principal component analysis (PCA). The sediment samples and fractions obtained by ultrafiltration of river water samples were freeze dried prior to characterization. The sediment samples were also extracted using 2 M sodium hydroxide solution. The extracts were ultrafiltrated, freeze dried and c…