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Refrigerants with a low global warming potential (GWP) possess mild flammability. Hence, a fundamental understanding of their combustion characteristics is required to assess their fire-hazardous potential. The laminar burning velocity is one fundamental property to describe these under safety evaluation aspects. However, measuring laminar burning velocities for slow-burning components, such as low-GWP alternatives, is challenging. This is due to influencing effects such as buoyant flame deformation, stretch, radiation, and confinement, especially at the flammability limits. In the present study, we investigated near-limit flames of the representative refrigerant difluoromethane (CH 2 F 2) with nitrogen-enriched oxidizer mixtures to elucidate the potentials and limitations at ultra-slow flame speeds of two widely used flame speed measurement methods in the closed vessel configuration: the optical flame speed measurement in the early quasi-isobaric regime and the flame speed determination from the pressure-rise during the later phase of the isochoric combustion process. Experiments were performed under terrestrial- and microgravity, conducted in a specially designed setup suitable for drop tower applications, using both methods in parallel. Recommendations for the extraction of flame speed data are derived from the non-buoyant reference investigations under microgravity and transferred to ultra-slow flames at terrestrial gravity. Near-limit flames under microgravity were found to be significantly affected by stretch effects for the optical method so that flame speed extrapolations to unstretched conditions are prone to errors. Stretch also affects the pressure method's lower evaluation limit, and errors can be estimated by combining flame speed data from the pressure method and Markstein lengths from optical experiments. [ABSTRACT FROM AUTHOR]

An adsorption cooling system (ACS) offers distinct advantages over conventional systems, including improved energy efficiency, waste heat power, low-emission refrigerant employment, and simplified mechanical design. The performance of ACS is greatly affected by the selection of the adsorbent/refrigerant pair. In this study, we experimentally investigate the adsorption capacity of difluoromethane (CH 2 F 2) onto several highly porous waste palm-based activated carbons (PACs). Elemental analysis, SEM, XRD, and FT-IR spectroscopy are performed on raw, carbonized, and activated samples to gain deeper insights into their surface morphology and functional groups. Difluoromethane adsorption isotherms of the PACs are obtained using a high-precision thermogravimetric analyzer at typical operating adsorption and desorption temperatures of ACS. One of the studied PAC/difluoromethane pairs achieves a benchmark uptake of 2.741 kg difluoromethane per kg adsorbent at 30°C and 1893 kPa equilibrium pressure. The experimental data are correlated with substantial accuracy using the Dubinin-Astakhov (D–A) and Tóth isotherm models to predict adsorption performance under experimentally unexamined operating conditions. Furthermore, for this PAC/difluoromethane pair, key performance indicators such as specific cooling effect (SCE), coefficient of performance (COP), Clapeyron cycle (P-T-W) diagram, and heat of adsorption (Q st) are evaluated. The results demonstrate that the PAC/difluoromethane pairs have excellent potential for the development of high-performance, low-emission ACS. [Display omitted] • Functional groups and crystallinity of raw waste palm and the synthesized activated carbons (PACs) were elucidated. • Difluoromethane adsorption characteristics of PACs were investigated at above and below critical temperatures. • A benchmark uptake of 2.741 k g r e f k g a d s − 1 was attained, surpassing similar pairs in the available literature. • Assessed SCEs and COPs elucidate an excellent potential for employing PAC/difluoromethane pairs in next-gen heat pumps. • A low-temperature heat source can provide high effective uptake in the operating pressure regions. [ABSTRACT FROM AUTHOR]

We present a wide-ranging correlation expressed in terms of temperature and density for the viscosity of difluoromethane (R-32) based on critically evaluated experimental data. The correlation is designed to be used with an existing equation of state from the triple point to 425 K and at pressures up to 70 MPa. Comparisons with experimental data over the temperature range 220 K to 425 K at pressures up to 70 MPa indicate the correlation has an estimated uncertainty (at the 95% confidence level) of 3.4% in this region, and 2% for the vapor at atmospheric pressure. The correlation also behaves in a physically reasonable manner and may be extrapolated up to 350 MPa, but caution is advised in this region since it requires extrapolation of the equation of state. [ABSTRACT FROM AUTHOR]

The role of non‐covalent interactions (NCIs) has broadened with the inclusion of new types of interactions and a plethora of weak donor/acceptor partners. This work illustrates the potential of chirped‐pulse Fourier transform microwave technique, which has revolutionized the field of rotational spectroscopy. In particular, it has been exploited to reveal the role of NCIs' in the molecular self‐aggregation of difluoromethane where a pentamer, two hexamers and a heptamer were detected. The development of a new automated assignment program and a sophisticated computational screening protocol was essential for identifying the homoclusters in conditions of spectral congestion. The major role of dispersion forces leads to less directional interactions and more distorted structures than those found in polar clusters, although a detailed analysis demonstrates that the dominant interaction energy is the pairwise interaction. The tetramer cluster is identified as a structural unit in larger clusters, representing the maximum expression of bond between dimers. [ABSTRACT FROM AUTHOR]

Due to their high global warming potential (GWP), hydrofluorocarbon refrigerants are systematically being phased out. Replacements with low GWP exist, but give rise to safety hazards as they are found to be mildly flammable. The assessment of the safety hazards of such fluids is typically based on their laminar flame speeds. Typical laminar flame speeds are below 10 cm/s, and hence are challenging to measure. Flames propagating at this speed are strongly affected by radiation heat loss and have to be corrected if considered for kinetic model validation. In the present study, the laminar flame speed of the representative refrigerant difluoromethane (CH 2 F 2 , R-32) is measured experimentally in an outwardly propagating flame configuration at elevated pressure and temperature. To assess radiation heat loss effects, detailed simulations using a recent kinetic model for CH 2 F 2 are conducted. Flame speed reductions due to radiation are found to be in the order of 15%. An analytical radiation correction model, as discussed by Santner et al. (2014), is adopted and its suitability for refrigerant/air flames is demonstrated based on simulation. After subsequent correction of experimental results, the predictability of the model is evaluated, showing good agreement. [ABSTRACT FROM AUTHOR]

• Experimental measurements of the adsorption characteristics of MSC30+R32 over a wide temperature range. • Development of an improved adsorption potential model for predicting isotherm data of various adsorbent-adsorbate pairs under supercritical conditions. • Validation of the proposed models using experimental data and comparison with traditional empirical equations. • Evaluation of the performance of an adsorption heat pump utilizing MSC30/R32 as the working fluid under supercritical conditions, with insights into the underlying mechanisms. In the present study, the adsorption isotherms of difluoromethane (R32) on the activated carbon (MSC 30) throughout a temperature range of 25 °C to 150 °C and pressures up to 3000 kPa are measured for possible application in adsorption cooling systems. The Dubinin-Astakhov model was used to fit the experimental data. A thermodynamic model is proposed in this study to investigate the adsorption potential under supercritical conditions. The model is validated using the isotherm data from the experiments and literatures for different working pairs. The validation results exhibited a good agreement between the proposed model and the experimental data, signifying the precision and dependability of the model. The corresponding adsorption isosteric heat model was derived and verified, taking into account both the inclusion and exclusion of the adsorbed volume correction. Furthermore, the developed models were utilized in the equilibrium analysis of an adsorption heat pump to evaluate the performance of the system in terms of the theoretical coefficient of performance (COP) and specific cooling energy (SCE). The analysis covered the driving heat source temperature ranging from 30 °C to 150 °C, with different evaporation temperatures and adsorption temperatures. The results showed that the maximum COP value of 0.47 for the adsorption heat pump system employing the MSC30+R32 pair was achieved at a desorption temperature of 115 °C, at which the SCE was 315.5 kJ·kg−1. The results can potentially improve the accuracy of predicting adsorption behavior and contribute to the development of more efficient and effective adsorption systems. [ABSTRACT FROM AUTHOR]

Abstract Compared to current refrigerants, next-generation refrigerants are more environmentally benign but more flammable. The laminar burning velocity is being used by industry as a metric to screen refrigerants for fire risk and it is also used for kinetic model development and validation. This study reports measurements of difluoromethane/air flame burning velocities for equivalence ratios from 0.9 to 1.4 in a spherical, constant volume device. Experimental burning velocities produced with the aid of an optically thin radiation model are about 17% greater than those obtained with an adiabatic model. Characterization of flame stretch based on the product of Markstein and Karlovitz numbers indicates that while many experimental data are nearly stretch-free, those for slower burning velocities, smaller flame radii, and leaner conditions may not be. Limiting the data to regions estimated to be stretch-free requires extrapolation away from the experimental conditions to extract burning velocities near ambient conditions, e.g., at (298 K, 101 kPa). Lower uncertainty, desirable for kinetic model validation, is obtained by interpolating between experimental conditions, e.g., at (400 K, 304 kPa). Since thermal radiation and flame stretch were found to affect the inferred burning velocities of difluoromethane/air constant volume spherical flames, these effects should also be considered during data reduction of other mildly flammable refrigerants. [ABSTRACT FROM AUTHOR]

Rotational spectra of several difluoromethane–water adducts have been observed using two broadband chirped‐pulse Fourier‐transform microwave (CP‐FTMW) spectrometers. The experimental structures of (CH2F2)⋅⋅⋅(H2O)2, (CH2F2)2⋅⋅⋅(H2O), (CH2F2)⋅⋅⋅(H2O)3, and (CH2F2)2⋅⋅⋅(H2O)2 were unambiguously identified with the aid of 18 isotopic substituted species. A subtle competition between hydrogen, halogen, and carbon bonds is observed and a detailed analysis was performed on the complex network of non‐covalent interactions which stabilize each cluster. The study shows that the combination of stabilizing contact networks is able to reinforce the interaction strength through a cooperative effect, which can lead to large stable oligomers. [ABSTRACT FROM AUTHOR]

Rotational spectra of several difluoromethane–water adducts have been observed using two broadband chirped‐pulse Fourier‐transform microwave (CP‐FTMW) spectrometers. The experimental structures of (CH2F2)⋅⋅⋅(H2O)2, (CH2F2)2⋅⋅⋅(H2O), (CH2F2)⋅⋅⋅(H2O)3, and (CH2F2)2⋅⋅⋅(H2O)2 were unambiguously identified with the aid of 18 isotopic substituted species. A subtle competition between hydrogen, halogen, and carbon bonds is observed and a detailed analysis was performed on the complex network of non‐covalent interactions which stabilize each cluster. The study shows that the combination of stabilizing contact networks is able to reinforce the interaction strength through a cooperative effect, which can lead to large stable oligomers. [ABSTRACT FROM AUTHOR]

Abstract In this study, silicon dioxide contact holes were etched with C 4 F 8 + CH 2 F 2 + O 2 + Ar gas plasmas, and the characteristics of the etching residue thereby generated inside the nanopatterns were investigated. The chemical composition of the etching residue formed on the sidewalls of the nano-contact patterns in the gas chemistry was investigated at various oxygen partial pressures by performing in situ Ar sputtering and X-ray photoelectron microscopy at different take-off angles. To investigate the effect of the plasma-active species (polymerizing radicals and charged species) on the formation of the etching residue, plasma diagnostics were conducted via optical emission spectroscopy and Langmuir probe measurements. It was found that as the oxygen content of the plasma increased, the thickness of the fluorocarbon (FC) polymer layer formed on the sidewalls of the nanopatterns decreased with a reduction in the FC polymer deposition rate of the plasma. In addition, at higher aspect ratios, the FC polymer layer showed a lower fluorine content. Highlights • The characteristics of the sidewall etching residue were investigated. • A thinner polymer was formed on the sidewall of the nanopatterns than on the surface. • The chemical composition of the sidewall residue varied with the profile depth. [ABSTRACT FROM AUTHOR]

The thermogravimetric method was employed to measure the adsorption kinetics of difluoromethane (R32) on MSC30 activated carbon powder adsorbent over a wide range of temperatures (25 °C to 150 °C) and pressures (up to 3000 kPa). The accuracy of various adsorption kinetics models, including FD model, LDF model, semi-infinite model, and modified adsorption kinetics models, were assessed to compare their suitability for predicting the kinetics uptake of the MSC30/R32 working pair. Based on the fitting of the Arrhenius equation, the activation energy E a and pre-exponential coefficient D s R p 2 were calculated to be 6262.37 (kJ·kg−1) and 0.00853 (s−1), respectively. The MSC30/R32 pair exhibited the highest diffusion time constant and adsorption rate among the common MSC30/refrigerant pairs. Furthermore, a new mass transfer coefficient model was proposed to enhance the accuracy and broaden the range of applicability of the existing model (Jribi model). Comprehensive validations were carried out using various adsorbent-adsorbate pairs over a wide temperature range. The Jribi model in conjunction with the proposed mass transfer coefficient model achieved high accuracy and precision in predicting the adsorption dynamics of diverse working pairs, both during the initial stage and near the saturation state. This study provides valuable insight into the adsorption kinetics analysis, which is essential in accurately simulating adsorption systems for various applications, including refrigeration and air conditioning. [ABSTRACT FROM AUTHOR]

Highlights • Adsorption of HFC-32 onto newly developed adsorbent is measured at 30–130 °C. • Highest HFC-32 adsorption (absolute) is recorded i.e. 2.34 g/g at 30 °C & 1.67 MPa. • During adsorption and desorption, there is no hysteresis for the studied pair. • Dubinin–Astakhov adsorption model fits the experimental data precisely. Abstract Adsorption and desorption of difluoromethane (HFC-32) onto newly developed phenol resin based adsorbent (SAC-2) have been measured experimentally for the isotherm temperatures ranging from 30 °C to 130 °C and pressure up to 3 MPa. A magnetic suspension balance based adsorption measurement unit is used to measure adsorption uptake gravimetrically. The presented SAC-2/HFC-32 pair has adsorption uptake as high as 2.23 kg ref /kg ads (excess adsorption) and 2.34 kg ref /kg ads (absolute adsorption) at 30 °C and 1.67 MPa. To the best of our knowledge, it is the highest HFC-32 adsorption capacity onto any adsorbent available in the literature. The experimental data of adsorption/desorption isotherms show that there is no hysteresis for the studied pair. The data have been fitted with Tóth; Dubinin–Astakhov (D–A); and Guggenheim, Anderson, De-Boer (GAB) adsorption isotherm models. The parameters of adsorption isotherm models are optimized by nonlinear optimization technique. The D–A model fits the experimental data precisely as compared to other models. In addition, numerical values of isosteric heat of adsorption have also been extracted by means of Clausius–Clapeyron equation using adsorption isotherm models. [ABSTRACT FROM AUTHOR]

Kinetics of the thermal decomposition reaction CH 2 F 2  → CHF + HF was studied by laser absorption measurements in a shock tube. The rate constants were determined by analyzing temporal profiles of HF produced in pyrolysis of CH 2 F 2 over the temperature range 1577–2214 K at pressure of ∼100 kPa in Ar bath. The results were well reproduced by master equation analysis based on RRKM theory and classical trajectory calculations, which gave the following rate constant expressions: k ∞  = 2.34 × 10 15 exp(−41,550 K/ T ) s −1 , k 0  = 5.33 × 10 25 ( T /K) −8.635 exp(−44,190 K/ T ) cm 3  molecule −1  s −1 , and F cent  = 0.13. [ABSTRACT FROM AUTHOR]

Difluoromethane (CH 2 F 2 ,HFC-32) presents strong ro-vibrational bands within the 8–12 μm atmospheric window and hence it represents a greenhouse gas able of contributing to global warming. Numerous spectroscopic studies have been devoted to this molecule, however, much information on line-by-line parameters, like line intensities and broadening parameters, is still lacking. In this work, line-by-line spectroscopic parameters are retrieved for several CH 2 F 2 ro-vibrational transitions belonging to the ν 7 band located around 8.5 μm. Self-broadening as well N 2 – and O 2 – broadening experiments are carried out at room temperature by using a tunable diode laser (TDL) spectrometer. The line shape analysis of CH 2 F 2 self-broadened spectra leads to the determination of resonant frequencies, integrated absorption coefficients and self-broadening parameters, while CH 2 F 2 –N 2 and CH 2 F 2 –O 2 broadening coefficients are obtained from foreign-broadening measurements. In addition, the broadening parameters of CH 2 F 2 in air are derived from the N 2 – and O 2 – broadening coefficients. The results of the present work provide fundamental information to measure the concentration profiles of this molecule in the atmosphere through remote sensing spectroscopic techniques. [ABSTRACT FROM AUTHOR]

The present work explores data reduction techniques for the measurement of the laminar burning velocities of R32(CH 2 F 2)-air mixtures using a constant volume combustion device, in which the pressure-time history is the only measured parameter. To allow clear assessment of the accuracy of the data reduction methods, the pressure-time histories used for analysis are synthetically generated via a detailed numerical simulation employing full kinetics and with and without an optically-thin radiation model. Various data reduction models are employed, including a two-zone model and two multi-zone models, and these are compared with the results from the burning velocity obtained from the output of the numerical simulation. The data reduction schemes are shown to be accurate if the same radiation model is employed in the data reduction as was used in the flame simulation to generate the pressure trace used for post-processing. If the incorrect radiation model is employed, however, the errors can be quite large. The effects of stretch, radiation, and different data post-processing methodologies are explored and the errors quantified. Stretch is shown to be important for the early stages and the selected data range that is used for extrapolation has a significant effect on the extrapolated burning velocity. However, with an appropriate choice of data considered for extrapolation, the prediction of the unstretched burning velocity can be quite accurate. [ABSTRACT FROM AUTHOR]

This paper presents progress of evaluation existing ejector of previous work with different gases, included real gas. This work was done by the Ansys simulation tool. The paper also discussed about the two solvers used for simulating real gas difluoromethane (R32). The results showed that entrainment ratios are almost not influenced by different gases but by the working conditions. Secondly, the solver pressure-based can obtain comparable results with the density-based one, while it is much more stable and solution converges faster than the density-based.

To further the deployment of adsorption cooling systems for various applications, the cooling potential assessment of novel activated carbon-based pairs with R32 refrigerant is carried out in this work. The compositions of Maxsorb-III activated carbon with H25 Graphene nanoplatelets (GNP), 1-Hexyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide ([HMIM][Tf 2 N]) ionic liquid, and polyvinyl alcohol (PVA), that have yielded the highest volumetric cooling energy (80:0:10:10) and thermal conductivity (40:40:10:10) respectively are considered for performance evaluation. The present study focuses on the under-explored aspect of heat exchanger optimization for HFC-based adsorbents through numerical analysis of two finned tube heat exchanger design configurations, viz., annular and longitudinal. A computationally less expensive numerical modeling is adopted, enabled by a scaling analysis. The impact of fin aspect ratios is analyzed for the composites with both the finned tube design configurations, and the significance of the adsorbent's thermal conductivity in realizing compact lightweight heat exchangers is highlighted. Further, an impact assessment of the adsorbent's orientation within the heat exchanger is presented for its anisotropic thermal conductivity characteristics. While it is observed that the annular fin configuration yields higher cooling performance for the composition 80:0:10:10, the longitudinal fin configuration yields a higher coefficient of performance for the composition 40:40:10:10 with a minimal decrement in the volumetric cooling power (<4.9%) over the annular fin configuration. The higher thermal conductivity of the composition 40:40:10:10 is seen to yield savings in the heat exchanger mass of up to 40.9% over that of the composition 80:0:10:10, for the same cooling capacity. The results indicate that present working pairs offer better cooling capacities and compact designs over other HFC-based studies in the literature. Pressure and temperature contours of the longitudinal finned configuration. [Display omitted] • First law-based evaluation of composite fractions on two finned tube design configurations. • Performance evaluation of novel carbon composites-R32 based adsorption cooling. • Parametric analysis with various operating conditions and heat exchanger designs. • Identification of appropriate heat exchanger configurations for the carbon composites. [ABSTRACT FROM AUTHOR]

The FTIR spectra of CH 2 F 2 have been investigated in a region of atmospheric interest (1000–1300 cm −1 ) where four fundamentals ν 3 , ν 5 , ν 7 and ν 9 occur. These vibrations perturb each other by different Coriolis interactions and the forbidden ν 5 borrows intensity from the neighboring levels. Furthermore, the v 4 =2 state has been found to interact with the v 3 =1 and v 9 =1 states by anharmonic and c -type Coriolis resonances, respectively. The spectral analysis resulted in the assignment of about 7500 rovibrational transitions which have been simultaneously fitted, together with microwave data available in literature (Hirota E. J Mol Spectrosc 1978; 69: 409–420) [15] using the Watson׳s A-reduction Hamiltonian in the I r representation and the relevant perturbation operators. The model employed includes eight types of resonances within the pentad ν 3 /ν 5 /ν 7 /ν 9 /2ν 4 . A set of spectroscopic constants for the four fundamentals as well as parameters for the v 4 =2 state and eighteen coupling terms have been determined. The simulations performed in different spectral regions well reproduce the experimental data. [ABSTRACT FROM AUTHOR]

We report results for the electrochemistry of the germanium(II) tri-halide anions, [GeCl3]−, [GeBr3]− and [GeI3]−, in supercritical difluoromethane containing 60 m m [N nBu4][BF4] at 19.1 MPa and 358 K. The voltammetry shows mass-transport-limited currents for reduction to germanium at gold on the first scan. There is no evidence of a germanium stripping peak and, on subsequent scans, the electrode slowly passivates with the deposition of approximately 0.4 μm of material. The redox potentials for the reduction of the three tri-halides are in the order [GeCl3]− <[GeBr3]− <[GeI3]−, with the iodide being the most easily reduced complex. Electrodeposition of germanium onto TiN electrodes from supercritical difluoromethane at 19.1 MPa and 358 K, using either 16 m m [EMIM][GeI3] with 60 m m [EMIM][BF4] or 16 m m [N nBu4][GeI3] with 60 m m [N nBu4][BF4], gave deposition rates of 2-3 μm h−1. Raman spectroscopy and transmission electron microscopy showed that the resulting germanium films were protocrystalline, containing nanocrystals of germanium embedded in an amorphous germanium matrix. [ABSTRACT FROM AUTHOR]

We have studied the electronic structure and property of pristine as well as Al-doped graphene sheets towards adsorption of some halomethane compounds (trichloromethane, dichloromethane, and difluoromethane) using density functional theory (DFhsT) calculations. The adsorption energies have been calculated for each adsorbed-adsorbent system. Based on our results, compared to pristine graphene, the Al-doped graphene causes significant adsorption energy, higher charge transferring, and smaller bond distances to halomethane compounds. Our calculated adsorption energies of trichloromethane, dichloromethane, and difluoromethane on Al-doped graphene were − 54.1, − 68.3, and − 123.2 kJ mol − 1 , respectively, which are categorized in the chemisorption region while the adsorption of these molecules on pristine graphene release insignificant energies which correspond to very weak adsorption on it. Furthermore, we used charge transfer analysis to search the amount of electron allocation. Orbital analysis including the density of states (DOS) was done to find the possible orbital hybridization between adsorbates and two graphene sheets. These results imply the suitability of Al-doped graphene as a good adsorbent/sensor for halomethane compounds. [ABSTRACT FROM AUTHOR]

We describe the assembly and characterisation of a reference electrode for use in supercritical difluoromethane (R32). The reference electrode is constructed from a europium doped lanthanum fluoride crystal contacted by silver loaded epoxy and encased in a silicate epoxy. The reference electrode can withstand pressures and temperatures up to at least 20 MPa and 360 K, typical operating condition for electrochemistry in supercritical difluoromethane (scR32). The performance of the new reference electrode is compared to that of a platinum pseudo reference electrode in scR32. The redox potential of the decamethylferrocene couple in scR32 containing 20 mM [NBu n 4 ][BF 4 ] at ∼17.6 MPa and 359 K was 0.088 ± 0.015 V against the new silver contacted lanthanum fluoride crystal based reference electrode. [ABSTRACT FROM AUTHOR]

Methane (CH) emissions from soils are erratic, the typical pattern being long periods of imperceptible emissions punctuated by short periods of high CH release. These short peaks are a result of higher gross CH production rates (methanogenesis) relative to gross rates of CH consumption (methanotrophy), and can be induced by rising water table level and periodic flooding in riparian soils. Soil fauna, specifically earthworms, affected soil CH cycling in some studies. We studied the effect of the endogeic earthworm Aporrectodea turgida (Eisen) on CH production and consumption activities in saturated and field-moist soils collected from a riparian area in southern Québec, Canada. Saturated (100 % water-filled pore space, WFPS) and field-moist soils (31.5 % WFPS) were incubated at 20 °C, with difluoromethane added to quantify gross CH production (i.e., methanogenesis activity) and consumption rates (i.e., methanogenic activity). The pattern of gross CH consumption followed that of gross CH production, and net CH production was an order of magnitude lower than the gross rate. Gross rates of CH production were 41 to 65 ng CH g h, gross CH consumption rates were estimated to be 37 to 63 ng CH g h, and the net CH production ranged from 2 to 4 ng CH g h. Saturated soils with earthworms had consistently lower net CH production, relative to field-moist and saturated soils without earthworms. This means that earthworms could potentially reduce the impact of periodic flooding on CH emissions from riparian soils. [ABSTRACT FROM AUTHOR]

This paper presents theoretical and experimental adsorption kinetics of Difluoromethane (HFC-32) onto activated carbon powder of type Maxsorb III and activated carbon fiber of type A-20. The experimental runs have been conducted on an apparatus that has been designed and built specially for this purpose. The adsorption kinetics have been determined at different adsorption temperatures ranging from 25 °C to 65 °C. The experimental data are reduced and fitted with linear driving force (LDF) and Fickian diffusion (FD) models. It has been found that both LDF and FD models are able to simulate the adsorption kinetics of HFC-32 onto activated carbon powder and fiber with an error of ±5%. [ABSTRACT FROM AUTHOR]

Although coupled cluster theory coupled to large basis sets can reach impressive accuracies for thermochemical and spectroscopic properties, it is still limited to small/medium sized molecules. Density functional theory (DFT) represents the working option for systems composed of hundreds to thousands heavy atoms. In this context, investigations are required aimed at characterizing the performances of the different density functionals (DF). This work focuses on the study of DFT performances in the prediction of spectroscopic properties, with particular attention to the vibrational problem, by focusing on the CH2F2 molecule as a test case. An extensive and systematic investigation is performed on several DFT model chemistries by testing their predictions of molecular constants and vibrational frequencies and intensities against CCSD(T)/aug-cc-pCVQZ data. B3LYP, B3PW91, B97-1, PBE0, TPSSh, M05, M05-2X, and B2PLYP DFs are used in conjunction with a variety of basis sets. Anharmonic frequencies are derived from the VPT2 treatment of anharmonic- and hybrid CCSD(T)/DFT-force fields. A software for VPT2 computations is also presented. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]