Impact of Vaping Regimens on Electronic Cigarette Efficiency.

Most recent studies on electronic cigarettes (e-cigs) have been carried out using vaping regimens consistent with mouth-to-lung inhalation (MTL) and not with direct-to-lung (DTL) inhalation. This paper aimed to characterizing the influence of inhalation properties (puff duration, puff volume, airflow rate) on the mass of vaporized e-liquid (MVE). Because the literature on DTL is non-existent, an intense vaping regimen consistent with DTL inhalation (i.e., puff volume = 500 mL) was defined. The use of a low or standard (ISO/DIS 20768) regimen and the proposed intense vaping regimen were first compared using the Cubis 1 Ω atomizer on a large power range, and then by using two atomizers below 1 Ω and two others above 1 Ω on their respective power ranges. An analysis of the e-cig efficiency on the e-liquid vaporization was proposed and calculated for each MVE. The intense vaping regimen allowed a broader power range in optimal heating conditions. MVE linearly increased with the supplied power, up to over-heating conditions at higher powers. Moreover, the e-cigs' efficiencies were higher when low-resistance atomizers were tested at high powers. All these results highlighted that the generated vapor might be better evacuated when an intense vaping regimen is used, and illustrate the obvious need to define a suitable standardized vaping regimen consistent with DTL inhalation.

Experimental Method of Emission Generation Calibration Based on Reference Liquids Characterization.

This work focuses on an experimental study of the influence of e-liquid composition on the mass of vaporized e-liquid after standardized emission generation using a U-SAV (Universal System for Analysis of Vaping) vaping machine. All the experiments were based on the use of a Cubis 1Ω clearomiser and on the standard protocol for electronic cigarettes emission generation. Currently, there is no standardized method available to calibrate the emission generations of electronic cigarettes. Since the e-liquid compositions are not always known, we propose a simple, practical, effective, and fast method of emission generation calibration. Therefore, this paper examines a major issue in this new and constantly evolving field, allowing the validation of the emission generation results. To our knowledge, this method is a novelty in our discipline and could be easily developed in laboratories. Pure propylene-glycol, glycerol, ethanol, and water and their mixtures (20 e-liquids) were tested as reference materials, allowing an e-liquids benchmarking and the characterization of 800 commercial e-liquids (with known and unknown compositions) at a fixed power and for one inhalation profile (3 s puff duration and 55 mL of puff volume). The influence of ethanol and/or water addition in the e-liquid was characterized.

Influence of Coil Power Ranges on the E-Liquid Consumption in Vaping Devices.

As electronic cigarettes (e-cigarettes) represent a new constantly evolving product category, the systematic analysis of the developed devices and the e-liquid vaporization is challenging. Indeed, understanding how e-cigarettes work and the role of key parameters in the process are major issues. This work focuses on an experimental study of how the power supplied by the battery to the atomizer coil influences e-liquid consumption. The reproducibility and the repeatability of e-liquid consumption were investigated over 20 series of 20 puffs for one of the tested atomizers. Then, the reproducibility and the repeatability of the e-liquid consumption was investigated over five series of 20 puffs for each tested atomizer. The wire behavior according to the supplied power could be separated into three regimes: under-heating (insufficient power to generate an aerosol), optimal vaporization characterized by a linear trend (vaporization of the e-liquid proportional to the supplied energy) and over-heating (dry-burn occurs). Using a controllable and repeatable energy supply, the reproducibility of the quantity of vaporized e-liquid was verified for each of the five series of 20 puffs programed for all the atomizers except one. Finally, the influence of the supplied power on the vaporization and the consumption of the e-liquid as well as the optimal power ranges were investigated and discussed. The results showed that atomizers with resistance ranging from 1 Ω to 1.8 Ω are efficient using all the energy supplied by the battery to vaporize the e-liquid and reducing the energy lost in the cotton or in the metal part of atomizer coil.

Influence of Implants Composition on Melatonin Release from Ethylcellulose Matrix.

BACKGROUND: Melatonin release from Ethylcellulose matrix has never been studied on the whole range of compositions. OBJECTIVE: To perform a comprehensive study about the influence of the melatonin loading on its release from solid ethylcellulose implants, from both a kinetic and structural point of view. METHOD: Cylindrical implants differing in their Melatonin:Ethylcellulose ratio were fabricated to cover a large range of compositions. Drug release was assayed by in vitro dissolution tests in CTAB micellar solutions. The 2D imaging of implant chemical composition during Melatonin release was performed by confocal Raman spectroscopy. FT-IR spectroscopy and Karl-Fisher technique were employed to study implants hydration. RESULTS: A drug radial leakage, whatever the implant composition, is imaged. The apparent diffusion coefficient, D of melatonin was evaluated considering Fickian radial diffusion: its value ranges from 2 to 6 10-12 cm2/s depending on the EC content. The variation of the characteristic drug delivery time with composition was non-monotonous and two different regimes were identified. CONCLUSION: A micellar transport of Melatonin was found. The two regimes in drug release were interpreted considering the polymer barrier effect, the initial porosity and M domains connectivity.

Direct technique for monitoring lipid oxidation in water-in-oil emulsions based on micro-calorimetry.

An experimental device based on the measurement of the heat flux dissipated during chemical reactions, previously validated for monitoring lipid oxidation in plant oils, was extended to follow lipid oxidation in water-in-oil emulsions. Firstly, validation of the approach was performed by correlating conjugated diene concentrations measured by spectrophotometry and the heat flux dissipated by oxidation reactions and measured directly in water-in-oil emulsions, in isothermal conditions at 60°C. Secondly, several emulsions based on plant oils differing in their n-3 fatty acid content were compared. The oxidability parameter derived from the enthalpy curves reflected the α-linolenic acid proportion in the oils. On the whole, the micro-calorimetry technique provides a sensitive method to assess lipid oxidation in water-in-oil emulsions without requiring any phase extraction.

Characterization of lipid oxidation in plant oils by micro-calorimetry.

A new experimental device was developed, based on the measurement of the heat flux dissipated during chemical reactions. The technique was exploited for real time monitoring of lipid oxidation in plant oils. The thermopiles were used in adiabatic configuration in order to measure the entire heat flux and improve sensitivity. Measurements were operated with a resolution of few µW as required to follow low exothermic reactions like oxidation. The validation of the device was performed by correlating conjugated diene concentrations measured by spectrophotometry and the heat flux dissipated by oxidation reactions. Our experimental approach involved several plant oils analyzed in isothermal conditions. This novel technique provides a versatile, sensitive, solvent-free and yet low-cost method to assess lipid oxidation stability, particularly suitable for the fast screening of plant oils.

Absolute self-calibrated room-temperature terahertz powermeter.

Coupling optical and thermal properties of a terahertz (THz) thermal converter based on the Seebeck effect provides an unsupplied room-temperature measuring device dedicated to THz power metrology. Performance characteristics such as broadband response (0-30 THz), high sensitivity (<25 µW·Hz(-0.5)), and the possibility to develop an internal absolute self-calibration estimated at 9.93 W·V(-1) are reported. Advantages and drawbacks of this THz powermeter are discussed.