Presence Of Ethanol Vapor Research Articles

PNIPAM Brushes in Colloidal Photonic Crystals Enable Ex Situ Ethanol Vapor Sensing.

Structural colors are formed by the periodic repetition of nanostructures in a material. Upon reversibly tuning the size or optical properties of the repetitive unit inside a nanostructured material, responsive materials can be made that change color due to external stimuli. This paper presents a simple method to obtain films of ethanol vapor-responsive structural colors based on stacked poly(N-isopropylacrylamide) (PNIPAM)-grafted silica nanoparticles. Our materials show clear, reversible color transitions in the presence of near-saturated ethanol vapor. Moreover, due to the absorption of ethanol in the PNIPAM brushes, relatively long recovery times are observed (∼30 s). Materials based on bare or poly(methyl methacrylate) (PMMA) brush-grafted silica nanoparticles also change color in the presence of ethanol vapor but possess significantly shorter recovery times (∼1 s). Atomic force microscopy reveals that the delayed recovery originates from the ability of PNIPAM brushes to swell in ethanol vapor. This renders the films highly suitable for ex situ ethanol vapor sensing.

False Positive Results of Phosphatidylethanol (PEth) Quantitation in Dried Blood Spots (DBS): The Influence of Alcohol Vapors

The role of phosphatidylethanol (PEth) as an alcohol consumption marker is increasing in clinical and forensic medicine. During the COVID-19 pandemic, the role of hygiene increased, and it became common practice to use disinfectants almost everywhere. This paper highlights a possible source of false positive results (by the vapors of alcohols during the blood spot drying process) in dried blood spots (DBS) by LC-MS/MS quantitation of PEth. To achieve this, the PEth quantitation method was validated according to FDA guidelines. Additionally, the synthesis of phosphatidyl derivatives by phospholipase D (PLD) in the presence of methanol and 2-propanol vapors during the DBS process was determined. Each PEth-negative sample from a healthy male patient incubated in the presence of ethanol vapor becomes PEth-positive. After 4 h of DBS drying, teetotalers become “moderate drinkers”. It is necessary to avoid using alcohol-containing disinfectants in treatment rooms, where DBS is sampled.

Effect of ethanol vapour sorption on the semiconductor-metal phase transition in powdered vanadium dioxide

We studied the effect of ethanol vapour on the parameters of the semiconductor-metal transition in a polycrystalline vanadium dioxide powder of the stable monoclinic phase a-VO2. It was synthesised by reducing vanadium pentoxide with oxalic acid while heated in air. The DC electrical resistance of the samples was studied between room temperature and 100оС in a tubular heater, in a microcompressor-generated air stream with saturated ethyl alcohol vapour. It was found that in the presence of ethanol vapour, the hysteresis loop shifted to higher temperatures by ten degrees and its cooling branch (corresponding to the transition of vanadium dioxide from the metallic phase to the semiconductor phase) became stepped.

Morphological, Structural, and Optical Properties of Doped/Codoped ZnO Nanocrystals Film Prepared by Spin Coating Technique and Their Gas Sensing Application

In today’s world of electronics, nanomaterial applications pose a challenge. The spin coating approach was used to create nanostructured ZnO with wurtzite structure in a recent study. Antimony doping, aluminum, and antimony codoping with 2.0 percent were used to make these films. The impact of doped and codoped films on structural, optical properties, and morphological has been examined using a variety of characterization approaches. A ZnO nanocrystal with a diameter of 20‐30 nm was discovered using XRD (X‐ray diffraction). According to SEM (scanning electron microscope) scans, the grain size is in the 80‐120 nm region. The use of Fourier transform infrared spectroscopy (FTIR) to detect elemental elements was studied, and the peak at 400‐520 cm-1 was identified as ZnO. The optical properties of doped and codoped ZnO were checked, and it was discovered that antimony‐doped ZnO has a larger band gap than Al and antimony‐codoped ZnO. This proved that ZnO may be used in gas sensors and solar cells. The gas response of a static gas sensor system based on Sb‐doped films was measured and compared to Al‐ and Sb‐codoped films in the presence of ethanol vapor.

Zinc(II) bis(dipyrromethenate)-doped ethyl cellulose sensors for ethanol vapor fluorescence detection

In this paper, we report on the results of spectrofluorimetric study of new fluorescent sensor based on [Zn2L2] doped in ethyl cellulose. The sensor optical signal is based on the rapid fluorescence quenching in the presence of ethanol vapor. The ethanol vapor detection limit in a gas mixture by means of sensor based on [Zn2L2] doped in ethyl cellulose is 0.56 ppt. Being highly sensitive and selective to the ethanol vapor presence, instant in response and easy to use, the sensor may find an application for the monitoring of the content of ethanol vapor in the air at industrial and laboratory facilities. This sensor can serve as the basis of pocket gas analyzers for detecting ethanol in the exhaled air.

Methane biofiltration in the presence of ethanol vapor under steady and transient state conditions: an experimental study.

Methane (CH4) removal in the presence of ethanol vapors was performed by a stone-based bed and a hybrid packing biofilter in parallel. In the absence of ethanol, a methane removal efficiency of 55±1% was obtained for both biofilters under similar CH4 inlet load (IL) of 13±0.5gCH4m-3h-1 and an empty bed residence time (EBRT) of 6min. The results proved the key role of the bottom section in both biofilters for simultaneous removal of CH4 and ethanol. Ethanol vapor was completely eliminated in the bottom sections for an ethanol IL variation between 1 and 11gethanolm-3h-1. Ethanol absorption and accumulation in the biofilm phase as well as ethanol conversion to CO2 contributed to ethanol removal efficiency of 100%. In the presence of ethanol vapor, CO2 productions in the bottom section increased almost fourfold in both biofilters. The ethanol concentration in the leachate of the biofilter exceeding 2200gethanolm-3leachate in both biofilters demonstrated the excess accumulation of ethanol in the biofilm phase. The biofilters responded quickly to an ethanol shock load followed by a starvation with 20% decrease of their performance. The return to normal operations in both biofilters after the transient conditions took less than 5days. Unlike the hybrid packing biofilter, excess pressure drop (up to 1.9cmH2Om-1) was an important concern for the stone bed biofilter. The biomass accumulation in the bottom section of the stone bed biofilter contributed to 80% of the total pressure drop. However, the 14-day starvation reduced the pressure drop to 0.25cmH2Om-1.

Chain Collapse and Interfacial Slip of Polystyrene Films in Good/Nonsolvent Vapor Mixtures

We investigated the dynamics and morphology of dewetting of metastable polystyrene films (thickness 75–500 nm) cast on silicon substrates, upon exposure to vapors of a mixture of toluene, a good solvent, and ethanol, a nonsolvent. Adding more than 2 wt % ethanol to the saturated toluene environment resulted in a dramatic increase in dewetting rate, an increase in the contact angle of polymer droplets and hole rims on the substrate, and extensive fingering leading to droplet shedding. Films preannealed close to Tg before exposure to the solvent vapors showed markedly slower dewetting. We conclude that in the presence of a good/nonsolvent mixture the polymer chains transition to a globule conformation, which leads to larger interfacial slip, lower viscosity, and significant elastic stress. The slip length derived in the presence of ethanol vapor is close to the values obtained for polystyrene on hydrophobized silicon. As the dewetting process is so significantly boosted by exposure to mixed toluene/ethanol ...

Synthesis and gas sensing behavior of nanostructured V2O5 thin films prepared by spray pyrolysis

Nanocrystalline vanadium pentoxide (V2O5) thin films have been deposited by a spray pyrolysis technique on preheated glass substrates. The substrate temperature was changed between 300 and 500°C. The structural and morphological properties of the films were investigated by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). The influence of different substrate temperatures on ethanol response of V2O5 has also been investigated. XRD revealed that the films deposited at Tpyr=300°C have low peak intensities, but the degree of crystallinity improved when the temperature was increased to 500°C and films had orthorhombic structures with preferential orientations along the (001) direction. The fractal analysis showed a decreasing trend versus the pyrolysis temperature. Sensing properties of the samples were studied in the presence of ethanol vapor. The operating temperature of the sensor was optimized for the best gas response. The response increased linearly with different ethanol concentrations. It was found that films deposited at the lowest substrate temperature (300°C) had the highest sensing response to ethanol.

Electrical characterization of ethanol sensing device based on Vanadium oxide/Porous Si/Si structure

Abstract A gas sensing device based on Vanadium oxide (V2O5)/Porous Si (PS)/Si structure has been used to detect ethanol vapor at different concentrations. The V2O5 thin films were deposited on porous silicon by sol-gel (Dip-coating) technique. The Vanadium oxide has been produced from vanadium alcoxide precursor. The capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics of Al/V2O5/PS/Si structure have been measured in the range from 1 Hz to 10 MHz frequency at room temperature in the presence of ethanol vapor. It is found that both C–V and G/ω–V of the capacitor are very sensitive to frequency and the sensor characteristics are modified in the presence of the gas. Conductance and capacitance measurements at low frequencies indicate the presence of interface states which can follow an alternating current (ac) signal that contributes to excess capacitance and conductance.

Optical system based on a CCD camera for ethanol detection

This work reports the optimization of an optical system used to detect and quantify volatile organic compounds (VOC). The sensor consisted of a polydimethylsiloxane (PDMS) sensing film deposited on a glass substrate by the spin-coating technique. The PDMS has the property of swelling and/or changing its refractive index when it interacts with molecules of VOC in vapor phase. In order to measure the PDMS swelling, a charge-coupled device (CCD) camera was employed to evaluate the interference fringe shift in a Pohl interferometric arrangement. With this approach, it is possible to use each pixel of the CCD camera as a single photodetector in the arrangement. Similarly, different computer algorithms were developed in order to acquire and process the obtained data. The improvements in the system allowed the acquisition and plot of 1 datum per second. The steady-state responses of the PDMS sensors in the presence of ethanol vapor were analyzed. The obtained results showed that noise level was reduced approximately three times after performing data processing.

Synthesis of multiwalled carbon nanotubes from bamboo charcoal and the roles of minerals on their growth

Abstract Multiwalled carbon nanotubes (MWCNTs) were synthesized from bamboo charcoals by chemical vapor deposition in the presence of ethanol vapor. Fresh bamboo culms were first heat treated at 1000–1500 °C to form charcoals. The elemental composition and structure of mineral phases in the bamboo charcoal treated at different temperatures were analyzed. The results showed that Mg 2 SiO 4 and particularly calcium silicate were responsible for the nucleation and growth of MWCNTs at 1200–1400 °C. Transmission electron microscope and energy dispersive X-ray spectrometer observations indicated that the tips of nanotubes synthesized at 1200–1400 °C consist mainly of calcium silicate. Such silicate tips acted as effective catalysts for nanotubes. The growth of MWCNTs followed the vapor–liquid–solid model including an initial decomposition of ethanol vapor into carbon, dissolution of carbon inside molten silicate and final nucleation of nanotubes.

Ethanol gas sensing properties of Al2O3-doped ZnO thick film resistors

The characterization and ethanol gas sensing properties of pure and doped ZnO thick films were investigated. Thick films of pure zinc oxide were prepared by the screen printing technique. Pure zinc oxide was almost insensitive to ethanol. Thick films of Al2O3 (1 wt%) doped ZnO were observed to be highly sensitive to ethanol vapours at 300°C. Aluminium oxide grains dispersed around ZnO grains would result into the barrier height among the grains. Upon exposure of ethanol vapours, the barrier height would decrease greatly leading to drastic increase in conductance. It is reported that the surface misfits, calcination temperature and operating temperature can affect the microstructure and gas sensing performance of the sensor. The efforts are, therefore, made to create surface misfits by doping Al2O3 into zinc oxide and to study the sensing performance. The quick response and fast recovery are the main features of this sensor. The effects of microstructure and additive concentration on the gas response, selectivity, response time and recovery time of the sensor in the presence of ethanol vapours were studied and discussed.

Size-controlled growth of TiO 2 nanowires by oxidation of titanium substrates in the presence of ethanol vapor

Size-controlled growth of single-crystalline TiO 2 nanowires by oxidation of titanium substrates was investigated. The growth was performed on titanium substrates in the presence of ethanol vapor at a low pressure and high temperatures. The results of characterization indicate that the mean diameter of the nanowires depends on the growth temperature whereas the mean length increases linearly with the growth time. In addition, a growth mechanism of the nanowires formed on the substrates in the presence of ethanol vapor is discussed.

Carbon nanotube synthesis from alcohols by a novel aerosol method

Single- and multiwalled carbon nanotubes (CNTs) were synthesised by a novel aerosol method using alcohols, namely ethanol and octanol, as carbon precursors. Preformed iron and nickel aerosol nanoparticles, produced by evaporation from resistively heated metal wire, were used as catalysts. Multiwalled CNTs were initiated by 10 nm sized catalyst particles and produced in the presence of ethanol vapour with the partial pressure of 7072 Pa, while combination of 2.4 nm particles and decreased alcohol vapour pressure (123 Pa) resulted in the formation of mainly single-walled and a small fraction of double-walled CNTs. The effect of a promoter (thiophene) in the system was found to be very important for the synthesis of multiwalled CNTs, while only a 30% number concentration increase was found for the single-walled CNT production.

Surface plasmon resonance study on the optical sensing properties of nanometric polyimide films to volatile organic vapours

The optical sensing properties of nanometric polyimide films towards ethanol and methanol vapours have been investigated by surface plasmon resonance technique. To this purpose polyimide sensing layers have been deposited onto gold/glass substrates by glow-discharge-induced vapour deposition polymerization technique. The sensible layer shows reversible and stable responses to different concentrations of methanol and ethanol vapours. A linear dependence between the change in reflectivity and the vapours concentration is observed being the sensitivity to both vapours similar, however, the response is larger in presence of ethanol vapours. Numerical fitting routines on surface plasmon resonance curves indicate that optical changes are motivated by an absorption process of the analyte. This produces a detectable increase of the real refractive index and a swelling process in the polyimide layer.

A NEW TREATMENT FOR A FILTER TIP TO DECREASE FLAVOR AND WATER MIGRATONS DURING STORAGE OF A TOBACCO PRODUCT

ABSTRACT Volatile flavors are playing an increasingly important role in the quality control of cigarettes to enhance their smoke taste and odor. The cigarettes which contain a filter tip having an activated carbon for reducing the irritant and physiological effects of the smoke are popular in the Japanese market. We found that the flavors migrate from the tobacco column to the filter tip, while spontaneously water moves backwards, depending on the adsorption equilibrium of cigarettes and its packaging.materials during storage. A new "Ethanol Adsorption Treatment" for a filter tip has been presented to decrease this undesirable flavor and water migrations. The treatment is performed by applying the binary vapor of water and ethanol to the filler tip before connecting ii with a tobacco column. Then during storage, the presence of ethanol vapor decreased the flavor migration mainly by decreasing the amounts of flavors adsorbed on the activated carbon within the filter lip. The treatment was confirmed to be effective for decreasing both flavor and water migrations simultaneously.

Differences in crystallization behavior between quenched and ground amorphous ursodeoxycholic acid.

To study the crystallization of ground and quenched ursodeoxycholic acid (UDCA) and to characterize their amorphous states. Amorphous UDCA was prepared by grinding and also by rapid cooling of the melt. These samples were characterized by powder X-ray diffraction (XRD), near IR spectra and dynamic water sorption. The heat associated with crystallization was measured in an isothermal microcalorimeter at 25 degrees C at various relative humidities (RH) (50%-100%) and, in the presence of the vapour from a mixed solvent of ethanol and water (ethanol conc. 10%-100%). The specific surface area was calculated from krypton adsorption. Contact angles were measured by using a Wilhelmy plate to calculate the surface energy of the samples. Ground and quenched samples yielded amorphous XRD patterns. Differential scanning calorimetry thermographs of the milled sample revealed that crystallization occurred at around 80 degrees C, whereas the quenched sample did not crystallize. Exposure to humid air did not result in crystallization of either amorphous sample during the microcalorimetric experiments. In the presence of ethanol vapour, the ground sample did, but the quenched sample did not, crystallize. The amount of water sorption into the quenched sample was larger than that of the ground sample at low RH. The surface energy of the quenched material was different to that of the ground. Peak shifts were observed in the NIR spectra at around 1450, 2100 nm, allowing differentiation between the ground and quenched samples. It can be concluded that different molecular states of amorphous UDCA were obtained depending on the preparation method. The crystallisation of amorphous UDCA was related to the molecular state of disorder.

Nano-hole formation on gold surface using scanning tunnelling microscope

, CO2, H2O or C2H5OH mixed with nitrogen gas; H2–Ar2 mixture) were applied in this study. Only the presence of ethanol vapour or water vapour helped to produce nano-holes when positive voltage pulse were superimposed on the sample. Furthermore, the existence of the critical vapour pressure of H2O or C2H5OH in the box was important in the modification of the gold surface and the etching process had an unitary rate when above critical vapour pressure. The linear relationship between the hole surface and the pulse duration was observed. We suggest that an anodic oxidation process of the gold surface under a voltage pulse and a place-exchange mechanism, involving the lifting of gold atoms in the surface monolayer, are relevant in nano-hole formation on the gold surface with STM. This process assisted by atom diffusion, due to the electric field built between the tip and the sample during the voltage pulse, explains the exceptional nano-hole geometry.

Sensitivity of a modified gateless FET structure to ethanol vapour

Evidence for the sensitivity to ethanol vapour of a modified n-channel FET structure, based on Si, was found. The detection is based on the increase in the drain current (at constant drain voltage) in the presence of ethanol vapour. Good ethanol sensitivity can be obtained using thin and ultrathin Si0 2 as well as a plasma nitrided thin thermal SiO 2 layer as an active dielectric. The response time is within seconds and the response range covers more than five decades for 100% ethanol vapour concentration in the working cell. The structure may operate as an alcohol sensor for about 150 measurement cycles without loss of detection speed or accuracy. The experimental results provide evidence that the rapid increase of the drain current is closely related to positive charge build-up in the structure during ethanol vapour exposure. Some concepts are proposed for the interpretation of the results obtained, including arguments used to isolate the contribution of the surface oxide charge on one hand, and the charge in the oxide and in the interface states on the other, to the total positive charge generated.

The mechanism of dehydrogenation of ethanol on magnesium oxide

The mechanism of dehydrogenation of ethanol was studied over magnesium oxide. It was found that in the course of the reaction ethoxide and acetate are formed on the catalyst. The ethoxide is one of the intermediates of the dehydrogenation, whereas the acetate does not participate in the reaction. Hydrogen was produced by the decomposition of ethoxide but no acetaldehyde was evolved in the gaseous phase simultaneously with hydrogen. Acetaldehyde was formed in the presence of ethanol vapor but not in its absence. In addition, it is demonstrated that the kinetic features of ethoxide on magnesium oxide are qualitatively from that on alumina.