Time evolution of near membrane layers

The near membrane layer is defined as a region where the concentration of the substance transported across the membrane drops $k$ times. The time evolution of such a layer is studied experimentally by means of the laser interferometric method. It is shown that within the experimental errors the thickness of the near membrane layer grows in time as $a \sqrt t$ with the coefficient $a$ being independent of the initial concentration and the membrane permeability. Time evolution of the near membrane layers is also analyzed within the theoretical approach earlier developed by one of us. The regularities found experimentally fully agree with the theoretical expectations.Comment: revised versio

An evaluation of sucrose as a possible contaminant in e-liquids for electronic cigarettes by hydrophilic interaction liquid chromatography–tandem mass spectrometry

The influence of sucrose combustion products on smoking and nicotine addiction is still controversial because the presence of the sucrose may be treated as a source of aldehydes and organic acids. In e-liquids used as refills for electronic cigarettes, which are made primarily of poly(propylene glycol), glycerine and ethanol, sucrose may be present at trace levels, and its impact on mainstream smoke formation, and hence on human health and smoking/nicotine addiction is unknown. An analytical method was developed where high-performance liquid chromatography in hydrophilic interaction liquid chromatography mode and tandem mass spectrometry were used for fast and simple determination of sucrose and other saccharides in e-liquids for electronic cigarettes. Minimal effort was required in the sample preparation step, and satisfactory results were obtained, and the sample matrix had an insignificant impact. The chromatographic separation was done using an Ascentis Express OH5 column (150 mm × 2.1 mm, 2.7 μm). The coefficients of variation for within-day precision for three concentrations were 2.4 %, 1.6 % and 2.3 %, and the between-day coefficients of variation for a single concentration were 2.1 %, 2.5 % and 1.7 % measured on the next 3 days. The detection limit was 0.73 μg/g, and the sucrose content in e-liquids ranged from 0.76 to 72.93 μg/g among 37 samples. Moreover, with the method presented it is possible to determine the presence of other saccharides such as fructose, glucose, maltose and lactose. However, only sucrose was found in all samples of e-liquids. The proposed method is rapid, simple and reliable in terms of high-performance liquid chromatography coupled with tandem mass spectrometry

New Design for Conserving Polymer Powder for the SIS Rapid Prototyping Process

Selective Inhibition of Sintering (SIS) is a Rapid Prototyping process that makes parts in a layerbased method by using polymer powders. Current SIS machines accomplish this layer-based method by heating a fixed area of polymer powder. The current process is an area of concern because the entire fixed area of each layer is cured, resulting in large amounts of polymer powder being wasted. This paper explains the design of an automated, mechanical system that will mask off areas of polymer powder with heat-resistant fingers, allowing for the adjustment of the heated area in order to cure minimal amounts of polymer powder at each layer. Test results of a prototype model showed significant reduction in polymer powder usage.Mechanical Engineerin

Validation of an Analytical Method for the Simultaneous Determination of Nine Intense Sweeteners by HPLC-ELSD

A collaborative trial was conducted to validate an analytical method for the simultaneous determination of nine intense sweeteners, i.e., acesulfame-K, alitame, aspartame, cyclamic acid, dulcin, neotame, neohesperidine dihydrochalcone, saccharin and sucralose in carbonated and non-carbonated soft drinks, and canned or bottled fruits. The procedure involves an extraction of the nine sweeteners with a buffer solution, sample clean-up using solid-phase extraction cartridges followed by an HPLC-ELSD analysis. Trueness, expressed in terms of recovery rates, was demonstrated in most cases by values ranging from 90 to 108%. High comparability of results obtained by individual testing laboratories was ensured by RSDR values <10% for the majority of results. Moreover, HorRAT values of less than 1.1 suggested for all sweeteners and matrices tested good performance of the method.JRC.D.8-Food safety and qualit

Predictors of Survival for Patients with Non-small Cell Lung Cancer and Synchronous Brain Metastases with FDG-PET/CT Staging

Purpose: The clinical course of patients diagnosed with non-small cell lung cancer (NSCLC) with brain metastases (BM) at presentation is variable. Here we seek to identify predictors of survival in patients staged with FDG-PET/CT. American Association of Physicists in Medicine (AAPM) 52nd Annual Meeting July 18-22, Philadelphia, P