Effect Of Ambient Atmosphere Research Articles

Analysis of Thermal Degradation Kinetics of POM under Inert and Oxidizing Atmospheres and Combustion Characteristics with Flame Retardant Effects.

Degradation behavior of combustible fuel is the core factor in determining combustion characteristics. To investigate the effect of ambient atmosphere on the pyrolysis process of polyoxymethylene (POM), the pyrolysis mechanism of POM was studied with thermogravimetric analyzer tests and Fourier transform infrared spectroscopy tests. The activation energy, reaction model, and estimated lifetime of POM pyrolysis under different kinds of ambient gases have been estimated in this paper based on different results of the kinetics. The activation energy values, obtained with different methods, were 151.0-156.6 kJ mol-1 in nitrogen and 80.9-127.3 kJ mol-1 in air. Then, based on the Criado analysis, the pyrolysis reaction models of POM in nitrogen were found to be mastered by the "n + m = 2; n = 1.5" model, and by the "A3" model in air. The optimum processing temperature for POM was estimated, with a range from 250 to 300 °C in nitrogen and from 200 to 250 °C in air. IR analysis revealed that the significant difference in POM decomposition between N2 and O2 atmospheres is the formation of isocyanate group or carbon dioxide. Combustion parameters of two POMs (with and without flame retardants) obtained using cone calorimetry revealed that flame retardants can effectively improve the ignition time, smoke release rate, and other parameters of POM. The outcomes of this study will contribute to the design, storage, and transportation of polyoxymethylene.

Effect of ambient atmosphere on the formation and evolution of conjugated structure of pre-oxidized polyacrylonitrile

The ambient atmosphere has the remarkable effect on the chemical reaction mechanism and the formation of characteristic chemical structures and conjugated structures for pre-oxidized polyacrylonitrile (PAN). In the present paper, fourier transform infrared spectroscopy (FT-IR) and ultraviolet visible spectroscopy (UV–vis) were used to characterize the variations of chemical reaction characteristic structures and conjugate structures of copolymerized PAN in nitrogen and air atmosphere, respectively. Combined with the multivariate reaction model proposed by the predecessors, it can be found that two main conjugated structures (conjugated polyene and conjugated aromatic heterocycle) formed during the pre-oxidation process of copolymerized PAN. In nitrogen atmosphere, the formed main structure units were the conjugated diene and conjugated double ring with 1–2 double bonds. By contrast, the formed main units in air were the conjugated diene and conjugated tricyclic with a double bond. During the whole pre-oxidation process, the maximum unit numbers of conjugated double bonds and conjugated rings were no more than four and six, respectively. Increasing the heat treatment temperature favored to form more conjugate structures than prolonging the heat treatment time. Furthermore, with the increase of heat treatment temperature or time in air, the main conjugate unit numbers had no obvious change, while the maximum unit numbers increased slightly. For the exposure in nitrogen atmosphere, the main conjugated polycyclic structure was transformed into conjugated tricyclic structure after the heat treatment at 250 °C for more than 3 h. In addition, when the heat treatment temperature and time were 280 °C for more than 4 h, the main conjugated polyene structure was transformed into conjugated triene, and the maximum conjugated unit numbers increased slightly.

Effect of Ambient Atmosphere on Abnormal Degradation Behavior in Metal-Oxide Thin-Film Transistor under Positive Gate-Bias and Temperature Stress

Effect of Ambient Atmosphere on Abnormal Degradation Behavior in Metal-Oxide Thin-Film Transistor under Positive Gate-Bias and Temperature Stress

Effect of Ambient Atmosphere on Abnormal Degradation Behavior in Metal-Oxide Thin-Film Transistor under Positive Gate-Bias and Temperature Stress

Proceedings of the International Display Workshops Volume 26 (IDW '19),Effect of Ambient Atmosphere on Abnormal Degradation Behavior in Metal-Oxide Thin-Film Transistor under Positive Gate-Bias and Temperature Stress

Controllable template approach for ZnO nanowire growth

Anodic aluminum oxide (AAO) is an optically transparent material with uniform hexagonal pores, which has widely been used as a template for nanowire growth. This study examines the potential of utilizing commercially available AAO to fabricate sub-10 nm ZnO nanowires by atomic layer deposition. The pore diameter of the AAO framework is reduced by controlled deposition of Al2O3. Subsequently, ZnO is deposited and ZnO nanowires are obtained. The analysis of structural and optical properties shows that the nanowires are polycrystalline, and exhibit a pronounced near band edge emission. Photoluminescence (PL) measurements are performed to monitor the effect of additional coating with Al2O3 and ZnO, on the optical stability of the AAO. The measurements indicate that the PL is highly influenced by the adsorption and desorption of species from the ambient at the surface. ALD deposition of a thin Al2O3 layer reduces considerably the effect of ambient atmosphere. The layer of Al2O3 facilitates PL characterization of very thin ZnO nanowires.

Effect of Ambient Atmosphere and Temperature on The Corrosion Resistance of X80 High-deformation Pipeline Steel in Bicarbonate Solution

Effect of Ambient Atmosphere and Temperature on The Corrosion Resistance of X80 High-deformation Pipeline Steel in Bicarbonate Solution

Synthesis of Borohydride and Catalytic Dehydrogenation by Hydrogel Based Catalyst

This paper deals with the synthesis of calcium borohydride (Ca(BH4)2) as hydrogen storage material. Calcium chloride salt (CaCl2), magnesium hydride (MgH2), and boron oxide (B2O3) were used as reactants in the mechanochemical synthesis of Ca(BH4)2. The mechanochemical reaction was carried out by means of Spex type ball milling without applying high pressure and temperature. Parametric studies have been established at different reaction times and for different amounts of reactants at a constant ball to powder ratio (BPR) 4:1. The best combination was determined by Fourier Transform Infrared (FT-IR) analysis. According to the FT-IR analysis, reaction time, the first reaction parameter, was found as 1600 min. After the reaction time was fixed at 1600 min, the difference of the B-H peak areas was dependent on the amount of reactant MgH2 that was investigated. The amount of the reactant (MgH2), the second reaction parameter, was measured to be 2.85 times more than the stoichiometric amount of MgH2. According to our previous studies, BPR was selected as 4:1 for all experiments. Samples were prepared in a glove box under argon atmosphere but the time that elapsed for FT-IR analysis highly affected B-H bonds. B-H peak areas clearly decreased with time because of negative effect of ambient atmosphere. A catalyst was prepared by absorbing cobalt fluoride (CoF2) in poly (acrylamide-co-acrylic acid) hydrogel matrices type and its catalytic dehydrogenation performance that has been characterized by the catalytic reaction of sodium borohydride's known hydrogen capacity in an alkaline medium. The metal amount of hydrogel catalyst was determined as 135.82 mg Co by Atomic Absorption Spectroscopy (AAS). The specific dehydrogenation capacity of the Co active compound in the catalyst thanks to catalytic dehydrogenation of commercial sodium borohydride was measured as 1.66 mL H2/mg Co.

Improvement of Long-Term Durability and Bias Stress Stability in p-Type SnO Thin-Film Transistors Using a SU-8 Passivation Layer

We investigate the effects of ambient atmosphere on the electrical performance of p-type tin monoxide (SnO) thin-film transistors (TFTs), and present the effective method for the passivation of SnO TFTs using a SU-8 organic layer. The experimental data shows that the SnO TFTs without a passivation layer suffer from the electrical performance degradation under humid environments, which implies that the formation of the passivation layer is necessary in p-type SnO TFTs for the stable operation of the devices. The SU-8 organic layer was successfully incorporated as a passivation layer of SnO TFTs. The SnO TFTs with a SU-8 passivation layer exhibit very similar transfer characteristics with those without a passivation layer, and show much improved long-term durability and bias stress stability compared with the SnO TFTs without a passivation layer under air environments.

Work function increase of transparent conductive electrodes by solution processed electron acceptor molecular monolayers

We show how the work function of transparent conductive oxide surfaces can be increased by more than 1 eV by solution-depositing strong electron acceptor monolayers comprising tetrafluoro-tetracyanoquinodimethane (F4TCNQ) or hexaazatriphenylene-hexacarbonitrile (HATCN). The effects of ambient atmosphere on the work function are investigated by comparing Kelvin probe measurements in air and ultraviolet photoelectron spectroscopy in ultrahigh vacuum. In this way, important technological issues related to the influence of ambient moisture on electrode properties are elucidated.

The Influence Of Atmospherics In Consumer Research Data Collection

<p class="MsoBodyTextIndent3" style="text-align: justify; margin: 0in 0.5in 0pt;"><span style="font-family: "Times New Roman","serif"; color: black; font-size: 10pt; mso-bidi-font-weight: bold;">This study investigates the effects of ambient atmosphere on market research survey response quality,</span><span style="font-family: "Times New Roman","serif"; color: black; font-size: 10pt;"> following approaches in the retail atmospherics literature. <strong style="mso-bidi-font-weight: normal;"><span style="mso-spacerun: yes;"> </span></strong>Participants<strong> </strong>completed a survey task<span style="mso-bidi-font-weight: bold;"> </span>and reported their affect states<span style="mso-bidi-font-weight: bold;"> in a </span>between subjects factorial experiment which manipulated ambient music, lighting and aroma conditions. Structural equation methods were used to test for effects of atmospheric factors on response quality and respondent affect. Findings suggest that ambient atmosphere may contribute to cognitive enrichment up to a point where it becomes distracting. At that point, ambient cues appear to interfere with cognitive processing. Survey response quality may be compromised through reduced positive affect, increased fatigue, or boredom, but the influence mechanism is different between males and females. The importance of <span style="mso-bidi-font-weight: bold;">stimulus manipulations is stressed and the effects of specific stimulus are provided to help researchers understand the impact toward response quality. Marketing researchers from both the academic and managerial community may be able to improve survey response quality by managing environmental conditions to enhance survey experience.</span></span></p>

Effects of Ambient Atmosphere on Electrical Characteristics of Al2O3 Passivated InGaZnO Thin Film Transistors during Positive-Bias-Temperature-Stress Operation

This study investigates the effects of ambient atmosphere on electrical characteristics of Al2O3 passivated InGaZnO thin film transistors during positive bias temperature stress. Under H2O vapor environment, the Al2O3 passivated device exhibited stable electrical behaviors (ΔV th < 0.5 V), while the unpassivated device showed an apparent hump effect in the transfer curves under bias stress. The hump phenomenon was attributed to the absorption of the H2O molecule which can serve as a donor to develop a conductive back channel. The experiment results suggest that Al2O3 is an effective passivation layer to suppress water vapor absorption in the InGaZnO back channel.

Effect of ambient atmosphere on crosslinking of polysilazanes

AbstractThe influence of ambient atmosphere on the crosslinking process of two commercially available polysilazanes with different molecular units in the backbone structure (one polysilazane with and one without urea units) was studied at different temperatures using oscillatory rheometry under isothermal conditions. The measurements were performed using cone/plate, plate/plate, and Couette geometries to assess the influence of the contact surface of the samples with air on their crosslinking behavior. The crosslinking process of the investigated polysilazanes in ambient atmosphere was found to occur faster than that in inert atmosphere. DSC and FTIR‐spectroscopic investigations indicate that hydrolysis and polycondensation processes occur in both polysilazanes when crosslinked in air. Interestingly, the effect of moisture was found to be more pronounced in the case of the urea derivative. The evolution of the measured complex viscosity and dynamic moduli supported this finding. Furthermore, the variation of the time derivative of complex viscosity (dη*/dt) emphasizes structural changes during crosslinking of the samples which were ascribed to their contact with the ambient atmosphere. This study emphasizes the high potential of rheometry in investigating the crosslinking behavior of polymers in inert and ambient atmosphere. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Effects of ambient atmosphere on the transfer characteristics and gate-bias stress stability of amorphous indium-gallium-zinc oxide thin-film transistors

We investigated the transfer characteristics and the gate-bias stability of amorphous indium-gallium-zinc oxide thin-film transistors when the channel layer was exposed to hydrogen, oxygen, air, or vacuum at room temperature during measurements. The threshold voltage and the drain current were changed by the ambient atmospheres. The threshold voltage shift (ΔVth) under gate-bias stress was faster in hydrogen than in oxygen and vacuum. It is suggested that hydrogen exposure degrades the gate-bias stress stability due to surface accumulation layer creation. The characteristic trapping times, τ, in H2, O2, air, and vacuum were 5×103, 1.5×104, 2×104, and 6.3×104 s, respectively.

Optical properties of zinc nitride thin films fabricated by rf-sputtering from ZnN target

RF-magnetron sputtering was employed to deposit zinc nitride films, from zinc nitride target, in plasma containing a mixture of Ar–N 2 gases. The effect of ambient atmosphere as well as thermal treatments (annealing in nitrogen and oxidation) on the optical properties of the films were examined. The transparency and conductivity of the films just after deposition were dependent on the amount of Zn in the structure. The films exhibited n-type conductivity and wide optical band gap. Annealing improved their transparency but they became more resistive. Oxygen was detected in films remained in the ambient atmosphere for a long period of time just after deposition, affecting transmissivity. Annealing promoted adsorption of oxygen in their structure, and the optical properties of high temperature annealed films resembled those of zinc oxide films having nitrogen as acceptor dopant. Band-edge emission peaks arising from acceptor exciton as well as nitrogen-related defect centers were revealed by low temperature photoluminescence.

Effects of atmospheres on bonding characteristics of silver and alumina

Joints prepared using the silver–copper oxide based reactive air brazing (RAB) technique are known to experience a significant decrease in joint strength when exposed to a high-temperature reducing environment. To investigate the effects of ambient atmosphere on the bonding characteristics of ceramic joints brazed with Ag–CuO filler metals, alumina joints prepared using a series of Ag–CuO compositions were exposed to a reducing hydrogen atmosphere and re-oxidized in air at 800 °C. As previously reported, joints exposed only to hydrogen revealed significant reduction in flexural strength and exhibited interfacial de-bonding between the filler metal and the alumina substrate. In the case of the joints brazed with a filler metal containing a high copper content, 8 mol% CuO, the formation of interfacial porosity caused by the reduction of interfacial oxide phases led to an extremely weak interface, which was not recovered after subsequent reoxidation in air at 800 °C. However, no such microstructural change or formation of interfacial porosity was observed in joints brazed with filler metals containing no or low copper content and the substrate/filler metal interface remained intact even though interfacial strength was found to be relatively weak. Subsequent reoxidation of these joints resulted in the recovery of interfacial strength and flexural strength. The results clearly indicate that interfacial adhesion in this type of braze filler metal is significantly influenced by the oxidizing/reducing characteristics of the surrounding atmosphere during high-temperature exposure. XPS analysis conducted on the in situ fractured surfaces of as-brazed and hydrogen-treated samples prepared using a filler metal with 2 mol% CuO indicates that it is the concentration of oxygen in the silver matrix which is critical to the level of bond strength between silver and alumina. This was confirmed by exposing an equivalent set of joining specimens to an inert atmosphere at high temperature, which subsequently also displayed low flexural strengths and de-bonding along the silver/alumina interface.

Mechanical properties of anodized coatings over molten aluminum alloy

A method to measure interfacial mechanical properties at high temperatures and in a controlled atmosphere has been developed to study anodized aluminum surface coatings at temperatures where the interior aluminum alloy is molten. This is the first time that the coating strength has been studied under these conditions. We have investigated the effects of ambient atmosphere, temperature, and surface finish on coating strength for samples of aluminum alloy 7075. Surprisingly, the effective Young's modulus or strength of the coating when tested in air was twice as high as when samples were tested in an inert nitrogen or argon atmosphere. Additionally, the effective Young's modulus of the anodized coating increased with temperature in an air atmosphere but was independent of temperature in an inert atmosphere. The effect of surface finish was also examined. Sandblasting the surface prior to anodization was found to increase the strength of the anodized coating with the greatest enhancement noted for a nitrogen atmosphere. Machining marks were not found to significantly affect the strength.

Effect of ambient atmosphere on penetration geometry in single laser and laser-arc hybrid welding. Welding phenomena in hybrid welding using YAG laser and TIG arc (second report)

YAG laser only or YAG laser-TIG arc hybrid welding was carried out on Type 304 stainless steel plate with a low S content in air or in the chamber with Ar gas including 0% to 15% oxygen gas. It was confirmed in both laser and hybrid welding that the penetration and geometry of welds depended upon the volume of the oxygen in the ambient atmosphere, and that a pronounced nail head part disappeared in a weld metal containing a higher content of oxygen in both the laser and the hybrid welding at 100 A. In addition, laser and hybrid welding were performed on polished Type304 plate with high S content and surface-oxidized Type304 plate with low S content in pure Ar atmosphere to discuss the influence of the minor element on the surface-tension driven melt flow. Then the geometry of their weld beads was similar to that made in the chamber with Ar and oxygen gas mixed. These experimental results suggest that convective flow induced by surface-tension driven force produces the upper part of the weld bead and consequently the weld displays a wine glass shape in both laser welding and hybrid welding at 100A in Ar atmosphere.

Influence of ambient atmosphere on metal-insulator transition of strained vanadium dioxide ultrathin films

The effect of ambient atmosphere on metal-to-insulator transition (MIT) in strained vanadium dioxide (VO2) ultrathin films (7–8nm) grown epitaxially on TiO2 (001) single crystal substrate by pulsed laser deposition was investigated by varying the ambient oxygen pressure and substrate temperature with the intention being to control arbitrarily the MIT events of strained VO2 ultrathin films, including the MIT temperature and the resistivity change. When reducing the ambient oxygen pressure, the MIT temperature remained almost constant, whereas the change of resistivity during MIT tended to be smaller. Contrary, varying the substrate temperature resulted in the variation of the MIT temperature with keeping the abruptness of transition. The lower the substrate temperature, the lower the MIT temperature, and in addition the MIT temperature ∼290K with keeping the abrupt change of resistivity is found to be the lowest compared with previously reported values. The reduction of the MIT temperature was found to correlate with shortening c-axis length when decreasing the substrate temperature, indicating the significant strain effects. Thus these results highlight that controlling appropriately the ambient atmosphere enables us to modulate arbitrarily the MIT events of strained VO2 thin films near room temperature.

Studies on solution and solution-cast film of polyaniline colloids prepared in the absence and presence of ultrasonic irradiation

Spectroscopic and voltammetric features for the solution and solution-cast film of polyaniline (PANI) colloids prepared in the absence and presence of ultrasonic irradiation were examined. Significant differences in the color and absorption spectra between the solution of colloids prepared in the absence and presence of irradiation were observed. Effects of ambient atmosphere on the solution of colloids were also studied. A gradual decay in the absorption at ≈365 nm was occurred upon ageing the solution in air for the colloid prepared under ultrasonic irradiation. PANI film, cast from its colloidal solution, exhibited excellent electroactivity. The films thus cast were applied to electrode modification to control electrochemical reaction. Clear voltammetric response was observed on the electrode modified with the colloid prepared in the presence of ultrasonic irradiation.

Effects of Ambient Atmosphere on Flame Spread over Solid Fuel 2nd Report Diluent Effect and Measurement of Gas Temperature.

To investigate effects of ambient atmosphere on flame spread, an experimental study has been conducted. The downward flame spread over solid fuel has been examined in a combustion chamber with a vertical duct to obtain uniform ambient atmosphere. The flame spread rate is measured with constant inflow velocity. Two kinds of paper sheet are used as samples. Ambient temperature is increased up to 150°C, and oxygen concentration is reduced to examine the diluent effect, adding carbon dioxide and nitrogen to the ambient air. The gas temperature is measured by thermocouples. Results show that, the flame spread rate is decreased with a smaller oxygen concentration, resulting in smaller heat flow into the preheat region, Q. Diluent effect of carbon dioxide is larger than that of nitrogen to reduce flame spread rate, with larger limiting oxygen concentration. In the gas temperature distribution, the maximum temperature is located around the flame zone, which is defined as the flame temperature. As oxygen concentration is decreased, the flame temperature is reduced. Hence, as the flame temperature is decreased, the heat flow into the preheat region is resultantly smaller. The temperature where the flame can not propagate is almost constant for all cases. Therefore, at extinction limit, the flame temperature is low so that the flame spread can not be supported due to smaller Q.