Atmospheric Temperature Range Research Articles

OH radical initiated oxidative degradation of imidacloprid in the environment: An assessment of breakdown kinetics and environmental hazards

Imidacloprid (IMI) is a common neonicotinoid pesticide that acts via a similar mechanism of action to nicotine, a naturally occurring insecticide. It is therefore important to understand its chemical fate in the environment. Hydroxyl radicals (HO) are significant oxidizing species in natural aquifers due to their strong reactivity towards organic substrates. Therefore, principal photo-oxidation products are expected to form with the involvement of HO in the self-cleaning process of water in nature. Here quantum chemical calculations are used to examine the reaction of IMI with HO in the atmosphere and aqueous environments. It was found that the principal mechanism of the HO + IMI reaction is the hydrogen transfer that, in a two-step process, produces stable cations in the gas phase. Within the atmospheric temperature range of 253–323 K, the overall rate constants for the HO + IMI reaction decreased from 4.35 × 1010 to 2.13 × 1010 M−1 s−1. Consequently, IMI can undergo rapid gaseous degradation within a comparatively brief period of 2.81 × 10−4 – 5.75 × 10−4 years. However, differences in environmental temperature and pH in aqueous environments influence the processes, rate constants, and products of IMI breakdown by the HO radical. The data indicate that IMI breakdown by OH radicals is strongly temperature and pH-dependent, resulting in the generation of different reaction products. The results imply that at all pH levels, the interaction between IMI and the ambient HO radical in water produces toxic chemical species. According to the computed data, it appears that IMI and the vast majority of degradation products present potentially carcinogenic and/or mutagenic hazards, and they also lack downstream biodegradability.

Determination of the hydration and carbonation kinetics of CaO for low-temperature applications

In this work, the reaction kinetics of CaO were investigated with interest in its application as a sorbent in the sorption-enhanced methanation process. Therefore, hydration and carbonation kinetics were studied under operating conditions analogous to those required by the process (i.e. atmospheric pressure and temperature range between 200 °C and 350 °C). Two different CaO-based materials were considered in this study. The experimental results indicated that a shrinking core model with chemical reaction control successfully predicted hydration and carbonation conversion for both CaO-based sorbents. The activation energy obtained was similar for both sorbents, being 1.69 kJ/mol and 1.76 kJ/mol for the hydration reaction and 22.27 kJ/mol and 21.60 kJ/mol for the carbonation reaction. Additionally, the present study investigated the impact of simultaneous hydration and carbonation reactions. Both sorbents showed a reduction in hydration capacity when CO2 was introduced into the reaction atmosphere due to the formation of a CaCO3 product layer.

Assessment of Climate Factors on Benthic Fauna in Jabi Lake Federal Capital Territory Abuja

Studies of climate factors on benthic fauna in Jabi Lake was conducted from November, 2016 to June, 2017 using combination of insitu and laboratory equipment. Three stations were selected to determine the climate characteristics based on activities in the various stations and proximity to terrestrial influence. The results of the climatic parameters showed that atmospheric temperature range 18.40 to 32.100C, rainfall from 1997-2016 range from 0.00 to 513.8mm, relative humidity range from 22.00 to 72.20%, wind speed range from 0.40 to 3.40m/s, variation with time in all the stations. There were significant differences (P<0.05) between these parameters, within the months, stations and seasons. A total of 1, 867 benthic fauna were collected and identified into 6 phyla, 27 families and 60 species. All the species identify were represented in all the stations. Faunistic composition and abundance of benthic fauna showed that Family Bithyniidae has the highest percentage composition 60% (1120) followed by Lymnaelidae and Nuculoidae with 4% each. Chironmidae has 3% while others has 2 to 1%. Similarity ratio computed by Jaccard’s similarities index (0.63) shows that the three stations has about 63% species similarities between them. The relationship between climatic variable and fauna in the CCA diagram shows only torant organisms on positive axis i.e. representative of Nematoda, Mollusca, Polifera and Annelida has affinity to variables while Crustacean and Arthropoda were senstive to environmental condition. The Shannon Weiner species diversity index is 0.96 which is quite high.

Теоретическая оценка эффективности применения одноступенчатых длинноходовых поршневых компрессоров в холодильной технике и системах сжижения углеводородов

The analysis of the main modern technologies for obtaining low temperatures and liquefying hydrocarbons using compressor equipment is presented and the most significant results of research in the field of low-flow compressors based on low-speed, long-stroke piston stages are presented. A method for calculating an ideal vapor-compression refrigeration cycle is presented, adapted to the object under consideration, taking into account the possibility of implementing quasi-isothermal compression. A comparative computational analysis of temperature conditions and thermodynamic efficiency of a two-stage refrigeration cycle and single-stage refrigeration cycles is carried out during adiabatic and quasi-isothermal compression processes in the boiling temperature range 278 K ... 198 K. It is shown that in terms of the discharge temperature and coefficient of performance, a single-stage vaporcompression ammonia refrigeration machine based on a low-speed quasi-isothermal stage is comparable to a similar two-stage machine based on adiabatic stages. This allows, in relation to actual objects — small refrigeration machines and installations, to predict both the energy and technical advantages of using a single-stage scheme based on low-speed, long-stroke piston compressors. In addition, it has been shown that the effective use of such a compressor is also possible in hydrocarbon liquefaction systems, while ensuring their safe temperature conditions in a wide range of atmospheric temperatures.

Propagation of THz radiation in air over a broad range of atmospheric temperature and humidity conditions

As the need for higher data rates for communication increases, the terahertz (THz) band has drawn considerable attention. This spectral region promises a much wider bandwidth and the transmission of large amounts of data at high speeds. However, there are still challenges that need to be addressed before the THz telecommunications technology hits the consumer market. One of the recurring concerns is that THz radiation is greatly absorbed by atmospheric water-vapor. Although many studies have presented the attenuation of THz signals under different atmospheric conditions, these results analyze specific temperature or humidity values, leaving the need for a more comprehensive analysis over a wider range of climate conditions. In this work, we present the first study of the attenuation of THz radiation over a broad range of temperatures and humidity values. It is worth noticing that all of our measurements have been undertaken at atmospheric pressure unlike many previous studies where the pressure was not kept constant for various temperatures. Furthermore, we extend our analysis beyond the impact of absolute humidity on the bit error rate in THz communications. We also discuss the refractivity of the atmosphere, examining its variations across different temperatures and humidity levels. THz propagation is studied using two different measurement systems, a long-path THz time-domain spectrometer as well as a quasi-optic setup with vector network analyze. We also compare the results with the ITU-R P.676-13 propagation model. We conclude that the attenuation at the absorption peaks increases linearly with water content and has no dependence on the temperature, while the refractive index, away from absorption lines, namely at 300 GHz shows a sub-linear increase with humidity.

Paleoclimate quantitative reconstruction and characteristics of continental red beds: a case study of the lower fourth sub-member of Shahejie Formation in the Bonan Sag

Varied origins have the ability to construct the continental red beds, such as paleoclimate, provenance, drainage status, etc. Reconstructing paleoclimate is the key to investigate the origin. Thus, this paper outlines the normal distribution constrained method (NDCM) to reconstruct paleoclimate quantitatively and accurately during the lower fourth sub-member of Shahejie (Es4x) in the Bonan Sag, which is in low requirement of data and environmental conditions. Based on the NDCM, the paleoclimate is still in a long-term arid background as the potential evapotranspiration rates (PERs) are larger than 6 in the transgressive system tract (TST) and regressive system tract (RST) during the period of Es4x. The decreasing PERs that range from 6.28 to 6.04, decreasing atmospheric temperature range from 14.37 to 13.95 °C and increasing mean precipitation of the wettest month and mean precipitation of the driest month indicate the paleoclimate is breaking away from the hot and arid background from TST to RST. Meanwhile, the paleoclimate fluctuation develops decreasing frequency and increasing amplitude which can be inferred from the increasing standard deviation (std), Th/K and Th/U curves. The hot and arid background is still the main origin of red color during the Es4x. Moreover, the other origin may also develop since there is no clear law between red coloration and the developing location of sediments.

Reduction of temperature fluctuation in a South African shack house using phase change material insulation

The majority of South African informal settlements are made from corrugated profile galvanized metal sheets. These informal settlements are prone to temperature fluctuations due to high thermal conductivity of the metal sheet and its low thermal resistance to heat transfer between the exterior and the interior of the shack. Families have resorted to using fuels such as paraffin during cold days, which has resulted in fire outbreaks that ravage surrounding shacks. This study experimentally investigated the temperature fluctuations around a shack fitted with plank chipboard and one without. Energy plus 22.2.0 software was then used to simulate the temperature fluctuations effects after integrating a Phase Change Material (PCM) layer on the shack walls. From the experiments, the internal temperature fluctuations on the shack without the insulations reached close to +50 °C during the day, and −5 °C during the night. While the shack with insulation reached +25 °C during the day and 7 °C during the night. The temperature distribution inside the shack was observed to be uneven, with the top section of the shack at higher temperatures than the bottom section. The region and the location of the shack largely contributed to the temperature fluctuations. Simulations revealed that by integrating a PCM layer in the shack walls, temperature fluctuations were greatly reduced. A lower phase change temperature yielded greater results as the atmospheric air allowed the PCM to fully solidify and melt, thus releasing the latent heat energy. A phase change temperature between 17 and 19 °C was selected based on the average atmospheric yearly temperature range. A 30 mm thick PCM reduced the temperature fluctuations to between +14 °C and +16 °C. However, materials with high thermal conductivity are not well supported by the Conduction Finite Difference used to simulate the performance of a phase change material in energy plus, it is proposed to remove such thin and high conductive materials in the model.

Assessment of a physics-based retrieval of exoplanet atmospheric temperatures from infrared emission spectra

Abstract Atmospheric temperatures are to be estimated from thermal emission spectra of Earth-like exoplanets orbiting M-stars as observed by current and future planned missions. To this end, a line-by-line radiative transfer code is used to generate synthetic thermal infrared (TIR) observations. The range of ‘observed’ intensities provides a rough hint of the atmospheric temperature range without any a priori knowledge. The equivalent brightness temperature (related to intensities by Planck’s function) at certain wavenumbers can be used to estimate the atmospheric temperature at corresponding altitudes. To exploit the full information provided by the measurement we generalize Chahine’s original approach and infer atmospheric temperatures from all spectral data using the wavenumber-to-altitude mapping defined by the weighting functions. Chahine relaxation allows an iterative refinement of this ‘first guess’. Analysis of the $4.3\rm \, \mu m$ and $15\rm \, \mu m$ carbon dioxide TIR bands enables an estimate of atmospheric temperatures for rocky exoplanets even for low signal to noise ratios of 10 and medium resolution. Inference of Trappist-1e temperatures is, however, more challenging especially for CO2 dominated atmospheres: the ‘standard’ $4.3\rm \, \mu m$ and $15\rm \, \mu m$ regions are optically thick and an extension of the spectral range towards atmospheric window regions is important. If atmospheric composition (essentially CO2 concentration) is known temperatures can be estimated remarkably well, quality measures such as the residual norm provide hints on incorrect abundances. In conclusion, temperature in the mid atmosphere of Earth-like planets orbiting cooler stars can be quickly estimated from thermal IR emission spectra with moderate resolution.

Quantitative Kinetics of HO2 Reactions with Aldehydes in the Atmosphere: High-Order Dynamic Correlation, Anharmonicity, and Falloff Effects Are All Important.

Kinetics provides the fundamental parameters for elucidating sources and sinks of key atmospheric species and for atmospheric modeling more generally. Obtaining quantitative kinetics in the laboratory for the full range of atmospheric temperatures and pressures is quite difficult. Here, we use computational chemistry to obtain quantitative rate constants for the reactions of HO2 with HCHO, CH3CHO, and CF3CHO. First, we calculate the high-pressure-limit rate constants by using a dual-level strategy that combines conventional transition state theory using a high level of electronic structure wave function theory with canonical variational transition state theory including small-curvature tunneling using density functional theory. The wave-function level is beyond-CCSD(T) for HCHO and CCSD(T)-F12a (Level-A) for XCHO (X = CH3, CF3), and the density functional (Level-B) is specifically validated for these reactions. Then, we calculate the pressure-dependent rate constants by using system-specific quantum RRK theory (SS-QRRK) and also by an energy-grained master equation. The two treatments of the pressure dependence agree well. We find that the Level-A//Level-B method gives good agreement with CCSDTQ(P)/CBS. We also find that anharmonicity is an important factor that increases the rate constants of all three reactions. We find that the HO2 + HCHO reaction has a significant dependence on pressure, but the HO2 + CF3CHO reaction is almost independent of pressure. Our findings show that the HO2 + HCHO reaction makes important contribution to the sink for HCHO, and the HO2 + CF3CHO reaction is the dominant sink for CF3CHO in the atmosphere.

Large Pressure Effects Caused by Internal Rotation in the s-cis-syn-Acrolein Stabilized Criegee Intermediate at Tropospheric Temperature and Pressure.

Criegee intermediates are important atmospheric oxidants, and quantitative kinetics for stabilized Criegee intermediates are key parameters for atmospheric modeling but are still limited. Here we report barriers and rate constants for unimolecular reactions of s-cis-syn-acrolein oxide (scsAO), in which the vinyl group makes it a prototype for Criegee intermediates produced in the ozonolysis of isoprene. We find that the MN15-L and M06-2X density functionals have CCSD(T)/CBS accuracy for the unimolecular cyclization and stereoisomerization of scsAO. We calculated high-pressure-limit rate constants by the dual-level strategy that combines (a) high-level wave function-based conventional transition-state theory (which includes coupled-cluster calculations with quasiperturbative inclusion of quadruple excitations because of the strongly multiconfigurational character of the electronic wave function) and (b) canonical variational transition-state theory with small-curvature tunneling based on a validated density functional. We calculated pressure-dependent rate constants both by system-specific quantum Rice-Ramsperger-Kassel theory and by solving the master equation. We report rate constants for unimolecular reactions of scsAO over the full range of atmospheric temperature and pressure. We found that the unimolecular reaction rates of this larger-than-previously studied Criegee intermediate depend significantly on pressure. Particularly, we found that falloff effects decrease the effective unimolecular cyclization rate constant of scsAO by about a factor of 3, but the unimolecular reaction is still the dominant atmospheric sink for scsAO at low altitudes. The large falloff caused by the inclusion of the stereoisomerization channel in the master equation calculations has broad implications for mechanistic analysis of reactions with competitive internal rotations that can produce stable rotamers.

Solubility, MD simulation, thermodynamic properties and solvent effect of perphenazine (Form I) in eleven neat organic solvents ranged from 278.15 K to 318.15 K

Perphenazine has rather effective in the treatment of mental illness. In this work, the solid-liquid equilibrium data of perphenazine in eleven organic neat solvents were determined by laser dynamic method under the atmospheric pressure and temperature range of 278.15 K ∼ 318.15 K. The selected solvents were n-propanol, n-butyl alcohol, methyl acetate, ethyl acetate, n-propyl acetate, n-amyl acetate, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAC), acetone, 2-methoxyethanol, glycol ether, respectively. From the results, the solubility of perphenazine is all positively correlated with temperature. Separately, we have adopted the KAT-LSER model and molecular dynamics simulation to investigate the influence of solvent effects and solute-solvent interaction on solute solubility. Meanwhile, there were four activity coefficient models being used to correlate the solubility data and Average relative deviation of models are 4.13% (Margules model), 3.94% (NRTL model), 4.49% (NRTL-SAC model) and 3.06% (UNIQUAC model), respectively, all of which do not exceed 5%. It manifests that the four activity coefficient models can fit the experimental values well, in which the UNIQUAC model gives the best regression effect. Moreover, the apparent thermodynamic properties(△solG°, △solH° and △solS°) of perphenazine in various solvents were calculated by Van’t Hoff equation. In accordance with the analysis and calculation of dissolution, the dissolution process is an endothermic entropy-driven process. This research can provide basic data for the crystallization process of perphenazine.

Electrically, Thermally, and Mechanically Anisotropic Gels with a Wide Operational Temperature Range

AbstractNext‐generation applications, such as flexible electronic devices, sensors, actuators, and soft robotics, require anisotropic functional soft materials with controlled, directional electrical and heat conductivities, mechanical properties, and responsiveness, as well as shape‐morphing capability, complex designability, and wide operational temperature ranges. However, a combination of these functions in any single class of materials has been very rarely seen to date. In this study, a novel class of multi‐anisotropic gels is developed to realize all these functions through a new fabrication route. The gels are synthesized by integrating cellulose with poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) in tripropylene glycol. The prepared gels exhibit high electrical and thermal conductivities of ≈200 S m−1 and ≈1.49 W m−1 K−1, respectively, with exceptional Young's modulus (≈500 MPa) and tensile strength (≈55 MPa), which are much better than the previously reported mechanical properties of PEDOT‐based gels (modulus/strength ≤ 10 MPa). Moreover, the gels exhibit self‐welding ability and maintain their properties for 14 d over a wide temperature range (from −50 to 35 °C), covering almost the entire atmospheric temperature range on Earth surface. It is believed that the developed gels are promising candidates for application in many next‐generation flexible devices, some of which are experimentally demonstrated in this study.

Methane dry reforming over nickel-based catalysts: insight into the support effect and reaction kinetics

The nickel-based catalysts supported on MgO-modified α-Al2O3, CeO2, and SBA-15 were prepared by impregnation method and investigated by N2 physisorption measurements, powder X-ray diffraction, Raman spectroscopy, H2 temperature-programmed reduction, CO2 temperature-programmed desorption, and transmission electron microscopy. Investigation of the kinetics of the dry reforming of methane (DRM) was carried out in gradientless circulating micro-flow system at atmospheric pressure and temperature range of 600–800 °C. The results showed that carriers have a prominent role in characterising the physico-chemical properties of catalysts such as specific surface area, dispersity of active metal, reducibility and basicity that greatly affect the adsorption feature and activity of NiO catalyst. However, the kinetic equation of DRM on three catalysts was found to be written by a common fractional equation, following a dual-site Langmuir–Hinshelwood Hougen Watson model. The order in the catalyst reducibility and apparent rate constant was observed as follows: NiMg/Al<Ni/Ce<Ni/SBA, while the apparent activation energy (E) is in the opposite order. The highest activity was observed on the catalyst containing 31.2 wt% Ni supported on SBA-15.

Airborne measurement of peroxy radicals using chemical amplification coupled with cavity ring-down spectroscopy: the PeRCEAS instrument

Abstract. Hydroperoxyl (HO2) and organic peroxy (RO2) radicals have an unpaired spin and are highly reactive free radicals. Measurements of the sum of HO2 and RO2 provide unique information about the chemical processing in an air mass. This paper describes the experimental features and capabilities of the Peroxy Radical Chemical Enhancement and Absorption Spectrometer (PeRCEAS). This is an instrument designed to make measurements on aircraft from the boundary layer to the lower stratosphere. PeRCEAS combines the amplified conversion of peroxy radicals to nitrogen dioxide (NO2) with the sensitive detection of NO2 using cavity ring-down spectroscopy (CRDS) at 408 nm. PeRCEAS is a dual-channel instrument, with two identical reactor–detector lines working out of phase with one another at a constant and defined pressure lower than ambient at the aircraft altitude. The suitability of PeRCEAS for airborne measurements in the free troposphere was evaluated by extensive characterisation and calibration under atmospherically representative conditions in the laboratory. The use of alternating modes of the two instrumental channels successfully captures short-term variations in the sum of peroxy radicals, defined as RO2∗ (RO2∗=HO2+∑RO2+OH+∑RO, with R being an organic chain) in ambient air. For a 60 s measurement, the RO2∗ detection limit is &lt; 2 pptv for a minimum (2σ) NO2 detectable mixing ratio &lt; 60 pptv, under laboratory conditions in the range of atmospheric pressures and temperatures expected in the free troposphere. PeRCEAS has been successfully deployed within the OMO (Oxidation Mechanism Observations) and EMeRGe (Effect of Megacities on the transport and transformation of pollutants on the Regional and Global scales) missions in different airborne campaigns aboard the High Altitude LOng range research aircraft (HALO) for the study of the composition of the free troposphere.

(Invited) Characterization of Novel Nanostructured Terbium Doped Oxygen Rich Silicon Oxide for Photonic Applications

Rare earth doped silicon-based thin films can be used for light emitting applications, where the control of dopant type and concentration plays a significant role in the enhancement of optical functionalities [1]. In this work, nanostructured terbium (Tb) doped oxygen-rich silicon oxide (ORSO) samples were fabricated using a novel fabrication technique: integrated sputtering and plasma enhanced chemical vapor deposition (PECVD) [2]. The Tb dopant concentration in the ORSO host matrix was varied from 0.5 at. % to 17 at. % and post-deposition thermal annealing was performed in a wide range of temperatures in a N2 atmosphere. In addition, the presence of defects, one of the general physical problems limiting the emission efficiency of rare earth doped silicon-based materials, was investigated using a combination of photoluminescence measurements and positron annihilation spectroscopy (PAS).We discuss the influence of the Tb dopant concentration on the silicon nanocrystal growth and the formation of Tb silicate nanocrystals. A precipitation mechanism as a function Tb content and annealing temperature is proposed and tested using X-ray diffraction, photoluminescence, and microscopy techniques. Following post-deposition annealing at 1200 °C, all Tb ions agglomerate and form large nanocrystals with diameters reaching 50 nm (Fig. 1). Scanning transmission electron microscopy (STEM) analysis shows that these large nanocrystals are composed of Tb, silicon, and oxygen, however, no Tb remains in the amorphous regions of the silicon oxide matrix. Despite the oxygen-rich content, small silicon nanocrystals (Si-ncs) are formed in the matrix with a size distribution between 2 and 5 nm.The influence of hydrogen passivation and the contribution of trap states to the luminescence mechanism is discussed using the interdependency of the photoluminescence emission for the dominant Tb excited state (5D4 to 7F5) and the values of the S-parameter obtained from PAS. The values of the S- and W-parameters identify the traps at the interface between the amorphous silicon oxide host matrix and embedded nanocrystals.Finally, the solubility level of Tb ions is extended using this novel processing method and an optimized Tb concentration for the most luminescent matrix is suggested. High-temperature annealing promoted the formation of a different Tb silicate crystal phase than the phases observed in samples with lower Tb content. A fiber texture with no preferred orientation in the plane but growth direction of <200> is observed [Fig. 2]; however, samples with lower Tb content are fully random and show no distinct texture. The correlation between the nanostructure and emission properties is an important step to fabricating Tb-doped silicon oxide materials which can be potentially used in a variety of light emitting applications such as displays, solar cells, optical communications, and other silicon optoelectronic devices.Fig. 1 High-resolution transmission electron microscopy (HR-TEM) image of a focused ion beam (FIB) prepared Tb-doped ORSO thin film annealed at 1200 ℃ for 1 hour in N2 atmosphere.Fig. 2 A fiber texture is evident by the ring of intensity shown in the pole figure and no preferred orientation in plane is observed.

Noble metals supported on binary γ-Al2O3-α-Ga2O3 oxide as potential low-temperature water-gas shift catalysts

A high surface area binary Al2O3-Ga2O3 oxide (AlGa) (75% wt%/25 wt%) was prepared by a single-stage precipitation method, and then used as support for noble metal catalysts (3 wt% nominal metal content). Effect of noble metals (Os, Pd, Rh, and Pt) on the surface distribution and the type of species formed were investigated by SBET, XRD, SEM-EDS mapping, HRTEM, DRIFT-CO and XPS techniques and tested in the Water-Gas Shift (WGS) reaction carried out in a fixed bed reactor at atmospheric pressure and temperature range 160–400 °C. The activity tests revealed that the reactivity of the catalyst followed the order: Pd/AlGa > Pt/AlGa > Rh/AlGa > Os/AlGa. The Pd and Pt-based catalysts presented the light-off reaction temperature at about 280 °C while the Os and Rh-based ones were activated at 300 °C and 325 °C, respectively. For the best Pd/AlGa catalyst, the DRIFTS spectra of chemisorbed CO revealed the presence of isolated peripheral or basal palladium species suggesting the importance of those species for the WGS reaction. For the Pt/AlGa catalyst, the combined EDS mapping and HRTEM studies indicated the highest dispersion of the metal phase among the catalysts studied. In this case, the absence of a correlation between the catalyst activity and metal dispersion suggests that factors other than metal dispersion control its catalytic performance.

Analysis of Influence of Atmospheric Parameter Fluctuation on Condenser Pressure

The influence of atmospheric temperature, humidity and pressure fluctuation on the condenser pressure is analyzed by numerical simulation. The seasons are mainly divided according to the atmospheric humidity range, and the atmospheric data are classified according to the seasons, and the fluctuation range of atmospheric temperature, humidity and pressure in specific seasons is determined, and a simplified condenser pressure coupling calculation model is established. The hypothetical iterative procedure calculates the condenser pressure value within a certain seasonal range and a certain atmospheric parameter fluctuation range. The results show that the atmospheric temperature fluctuations have a great influence on the pressure of the condenser in the spring and autumn, atmospheric humidity and pressure fluctuations have a great influence on the condenser pressure in summer. The primary and secondary analyses were carried out on several parameters of the atmosphere. The influence of temperature on the pressure of the condenser was 93%, the weight of the humidity was 6.2%, and the weight of the pressure was 0.8%, which provided a basis for optimizing the operation mode of the cold end system.

Continuum absorption of millimeter waves in nitrogen

We report the results of experimental study for the N2 absorption in the millimeter wavelength range at pressure and temperature ranging, respectively, from 750 to 1500 Torr and from 265 to 310 K. The obtained data are shown to be in a good agreement with the previously published experimental results, as well as with the predictions issued from available empirical models of nonresonant absorption and from the simulation of the N2–N2 rototranslational collision-induced absorption performed recently using the classical trajectories method relying on complete ab initio potential and induced dipole surfaces. Analysis of the first spectral moments leads to a conclusion that the role of true bound (N2)2 dimer absorption is negligible at least in the range of atmospheric temperatures. New experimental data reported in this paper are supported by our theoretical modelling being however somewhat in excess of the data presented in the HITRAN/CIA database for the same spectral range. We consider our data as an update of the previously available so-called “dry” atmospheric continuum which is conventionally employed nowadays in the mm-waves propagation models.

DFT analysis on the removal of dimethylbenzoquinones in atmosphere and water environments: ·OH-initiated oxidation and captured by (TiO2)n clusters (n=1–6)

The elimination mechanisms and the dynamics of 2,5-dimethylbenzoquinone/2,6-dimethylbenzoquinone are performed by DFT under the presence of ·OH radical and TiO2-clusters. The rate coefficients, calculated within the atmospheric and combustion temperature range of 200–2000 K, agree well with the experimental data. The subsequent reactions including the bond cleavage of quinone ring, O2 addition or abstraction, the reactions of peroxy radical with NO yielding the precursor of organic aerosol are studied. Gaseous water molecule plays an important role in the transformation of alkoxy radical and exhibits a catalytic performance in the enol-ketone tautomerism. The lifetimes of 2,5-dimethylbenzoquinone/2,6-dimethylbenzoquinone are about 12.04–12.86 h at 298 K, which are in favor of the medium range transport of them in the atmosphere. Significantly, the water environment plays a negative role on the ·OH-degradation of dimethylbenzoquinone. Compared to the quinone ring, 2,5-dimethylbenzoquinone onto (TiO2)n clusters (n = 1–6) is easier to be absorbed by TiO2-clusters through its oxygen site because of its strong chemisorption, which indicates that TiO2-clusters are capable of trapping dimethylbenzoquinones effectively. The water environment could weaken the adsorption of 2,5-dimethylbenzoquinone onto (TiO2)n clusters (n = 1–6) by increasing the adsorption energy. This work reveals the removal of dimethylbenzoquinones and the formation of organic aerosol under polluted environments.

A comparison between GDP and PDP experiments of hydrogen permeation through 15 μm Pd60-Cu40% membrane thickness in a micro channel plate type reactor

This study analyses the performance of hydrogen permeation through thin palladium 60%-copper40% alloy membrane with a thickness of 15 μm in 1 mm gap length plate micro channel reactor (PMCR) under gas driven permeation (GDP) and plasma driven permeation (PDP). Pure hydrogen gas was fed into the PMCR at atmospheric pressure and temperature range of 423–573 K. The hydrogen permeation flux plot of GDP experiment versus the inverse temperature showed a continuous increase with the PMCR heating temperature, while in PDP experiment the trend behavior showed a small peak increase at plasma applied voltage 16 kV and temperature 573 K. The energy efficiency of both experiments were determined, it was found that the energy efficiency values of GDP experiment was higher than that obtained from PDP experiment due to the total heat added to the plasma system. Further, the maximum energy efficiency of GDP experiment was 63.37% at H2 flow rate 0.1 L/min and temperature 573 K, while in PDP experiment the maximum value was 48.7% at plasma voltage 14 kV, H2 flow rate 0.1 L/min and temperature 573 K. Further, the yield ratio evaluation versus the total energy consumptions was determined, the stronger effect on yield ratio was noted when the energy added to the system increased. A comparison between the yield ratios of both experiments has been developed, it was concluded that the influence of plasma on hydrogen permeation was higher than heating effect, additionally the plasma effect increased at low temperatures. The hydrogen output energy versus the energy consumption was compared, it was observed in GDP results that the output H2 energy very low at low temperature and increased to the maximum value 20.89 W at 573 K. While in PDP results, it was seen a continuous increase with discharge voltage to reach the maximum value 20.997 W at 14 kV and temperature of 573 K.