Noble Gas Research Articles

Stable and Radio-Isotopic tools to understand the groundwater recharge and dynamics of CHASHMA-Mianwali area, Pakistan

The study conducted on “Chashma-Mianwali” area to investigate the impact of canals, lake and rivers flowing through the area on groundwater recharge and dynamics of the area. Isotopic and noble gases data suggested localize impacts of canals, lake and river on groundwater recharge. Groundwater residence time using Tracer Lump Parameter Model (LPM), and Chloroflourocarbons (CFCs) data suggest a very young water in the range of 14–59 years. The real and filtration velocities of groundwater were found to be 22.2 cm/day and 10.94 cm/day, respectively, in south-west direction and in-situ effective porosity of the aquifer was 49.3 %. The hydraulic conductivity of the aquifer was estimated with average value of 143 m/day with Transmissivity (T) of 43,127 m2/day.

Radiological and Pulmonary Results of Surgical Treatment of Severe Idiopathic Scoliosis Using Preoperative Halo Gravity Traction Compared with Less Invasive Temporary Internal Distraction in Staged Surgery in Adolescents.

Background: Severe and rigid scoliosis represents a type of spinal deformity characterized by a Cobb angle exceeding 90° and a flexibility of less than 30%. Halo spinal traction remains the established standard for managing severe scoliosis, although alternative approaches such as temporary internal distraction rods and staged surgical correction exist. The primary objective of this investigation was to compare two cohorts of patients treated using these distinct methods to ascertain any divergences in terms of surgical and radiological outcomes, pulmonary function (PF), and quality of life (QoL). Methods: This study encompassed a total of 62 pediatric patients meeting the specified criteria, which included severe idiopathic scoliosis (major Cobb curve >90) and flexibility <30%. Group 1 (G1) underwent surgical intervention involving preoperative Halo gravity traction (HGT) succeeded by posterior spinal fusion (PSF). On the other hand, Group 2 (G2) underwent a two-stage procedure starting with a less invasive temporary internal distraction technique (LITID) prior to PSF. The radiological outcomes, PF, and QoL were documented and assessed over a monitoring period ranging from 2 to 5 years. Results: The average preoperative major curves (MCs) measured 124° and 122° in G1 and G2, respectively (p < 0.426). Initial flexibility, as observed in preoperative bending films, ranged from 18% in G1 to 21% in G2 (p < 0.001). Following the ultimate surgical intervention, the MCs were corrected to 45° and 37.4° in G1 and G2, respectively (p < 0.001). The percentage correction of the MCs was higher in G2 (63% vs. 70% in G1 and G2, respectively), with significant between-group disparities (p < 0.001). The mean preoperative thoracic kyphoses (TKs) were 96.5° in G1 and 92° in G2 (p = 0.782), which were rectified to 45.8° in G1 and 36.2° in G2 (p < 0.001), equating to correction rates of 55% and 60% in the respective groups. Initially, G2 exhibited lower values for the percentage of predicted lung volume (FVC) and predicted FEV1 compared with G1 (49% and 58% vs. 54.5% and 60.8%; N.S.). Nonetheless, both groups demonstrated enhancements in their FVC and FEV1 values over the follow-up period. Conclusions: The surgical management of severe and untreated spinal curvatures in the pediatric and adolescent population can be considered safe, with a tolerable incidence of minor complications. LITID emerges as a method offering improved QoL and pulmonary function, achieving notably substantial average corrections in deformity by 70% in the coronal plane and 60% in the sagittal plane, alongside a mean increase in trunk height of 10.8 cm. Furthermore, a typical reduction of 76% in rib humps and enhancements in respiratory function, as indicated by improvements in 1 s predicted forced expiratory volume (by 25-56%) and forced vital capacity (by 35-65%), were achieved, leading to a clinically and statistically significant enhancement in QoL when evaluated using SRS-22r, without resorting to more radical, high-risk procedures.

Noble gas characteristics of microbial gas in the Qaidam Basin, China: Implications for helium enrichment processes

Helium is a critical, strategic and nonrenewable resource with limited reserves and unstable supplies. However, the helium sources and migration processes in petroliferous basins remain unclear. The Qaidam Basin features multiple reservoir layers, multiple genetic types of natural gas, and varying helium concentrations, providing an ideal natural laboratory for understanding the helium enrichment processes. Here, we present the original noble gas isotopic compositions and major gas components of 11 microbial gas samples from three gas layers in the Sebei No.1 gas field, eastern Qaidam Basin, China. The helium isotopic ratios range from 0.007 to 0.057 Ra, reflecting a predominantly crustal source. The Quaternary Sebei microbial gas features much lower helium concentration (0.0003–0.001%), 21Ne/22Ne ratio (0.031–0.034), and 40Ar/36Ar ratio (292–380) than thermogenic natural gases in the Qaidam Basin. The middle gas layer (II) of the Sebei gas field features higher 21Ne/22Ne and 40Ar/36Ar ratios than the top and bottom gas layers, displaying positive correlations with higher 4He groundwater concentrations before degassing, as calculated from 4He/20Ne ratios and 20Ne concentrations in air-saturated water. However, the correlations between the 4He contents in natural gas and the 21Ne/22Ne and 40Ar/36Ar ratios are unclear, suggesting that 4He dissolves into the groundwater system before degassing into a gas reservoir and that the variations in the 4He concentration in the gas phase are caused by the different levels of hydrocarbon dilution. Quantitative calculations of helium production revealed an external helium flux from the crustal basement except for the in-situ production from sedimentary strata even in this broadly-defined self-generating and self-preserving natural gas system. The helium resources in the Qaidam Basin are mainly distributed in tectonically active zones with uplifted pre-Jurassic basement rocks (providing sufficient helium sources), ancient groundwater systems (accumulating more helium) and suitable hydrocarbon production (acting as a carrier gas but diluting helium as slightly as possible).

Délais d'attente d'implantation de valve aortique transcutanée (TAVI) et mortalité durant la période d'attente en Algérie

BackgroundTrans Aortic Valve Implantation (TAVI) has become the primary treatment for aortic stenosis in patients over 75 years old. Despite its clinical efficacy, it's adoption in emerging countries remains low due to the high cost of prostheses and limited healthcare funding resources. This leads to prolonged waiting times for the TAVI procedure, which may lead to complications; these data are missing particularly in emerging countries. AimsTo describe waiting time for TAVI and mortality rate in this waiting period. Materials and methodsThis was prospective registry, patients referred for TAVI were prospectively followed; waiting time was calculated from the first visit after referral to TAVI implantation, clinical and, call fellow up was performed every 3 months. We divided patients into two groups: Group 1 (G1) patients still awaiting TAVI (105 patients), and those who underwent TAVI (36 patients). Group 2 (G2) patients who died while awaiting TAVI (16 patients, 10,2 %). ResultsDemographic characteristics were similar, with a tendency for older age in G2 (79.5 ± 5.7 years vs. 82.5 ± 7.4 years, p=0,06). G2 exhibited more left ventricular ejection fraction (LVEF) impairment (8.5% vs. 25%, p=0,03) and a higher rate of severe heart failure with dyspnea stages III or IV (2.8% vs. 12.5%, p<0,001). The mean follow-up in G1 was 242.9 ± 137.4 days; the waiting time for TAVI was 231.7 ± 134.1 days, and the average time between the first consultation and death while awaiting TAVI (G2) was 335.1 ± 167.4 days. Conclusionin our series, waiting time is high due to limited Trans aortic heart valve availability, mortality during this wait exceeds 10%. Adverse prognostic factors include impaired LVEF and severe dyspnea stages III or IV.

A compared histopathological study on kidneys and eye bulbs in distinct clinical presentations of canine leishmaniasis by Leishmania infantum.

Canine leishmaniasis (CanL) caused byLeishmania infantumcommonly progresses with renal and ophthalmic lesions associated with active systemic disease. As chronic inflammation related to immune complex deposits is a pathophysiological factor in the development of both glomerulonephritis and uveitis, we aimed to evaluate renal and ocular histopathological lesions and analyze whether they were related to each other and the clinical degree of the disease. For that, we evaluated 15 dogs from CanL-endemic areas.L. infantumPCR-positive dogs were studied according to disease severity into two different groups: Group-1 (G1) had data from seven dogs with mild to moderate CanL and no history of treatment, and G2 was formed with eight dogs with severe to terminal disease that had not responded to CanL treatment. Histopathological analysis of kidneys showed higher frequencies and intensities of glomerular basement membrane thickening (p = 0.026), deposits in glomeruli (p = 0.016), epithelial necrosis (p = 0.020), tubular dilatation (p = 0.003) and interstitial fibrosis (p = 0.04) in G2 dogs than in G1 dogs. Surprisingly, the histopathology of eye bulbs showed a higher frequency and intensity of retinitis (p = 0.019) in G1 dogs than in G2 dogs. The comparative analysis showed that there was no correspondence between histopathological findings in kidneys versus eyes in milder or more severe CanL. Our findings suggested that (1) clinically undetectable eye alterations can be more precocious than those in kidneys in the development of CanL, and (2) the lower frequency of eye lesions and higher frequency of renal lesions in dogs with terminal disease even after treatment indicate that therapy may have been effective in reducing CanL-associated ophthalmic disease but not proportionally in reducing kidney disease.

Radon Exposure Assessment in Occupational and Environmental Settings: An Overview of Instruments and Methods.

Radon is a naturally occurring noble radioactive gas that poses significant health risks, particularly lung cancer, due to its colorless, odorless, and tasteless nature, which makes detection challenging without formal testing. It is found in soil, rock, and water, and it infiltrates indoor environments, necessitating regulatory standards and guidelines from organizations such as the Environmental Protection Agency, the World Health Organization, and the Occupational Health and Safety Agency to mitigate exposure. In this paper, we present various methods and instruments for radon assessment in occupational and environmental settings. Discussion on long- and short-term monitoring, including grab sampling, radon dosimetry, and continuous real-time monitoring, is provided. The comparative analysis of detection techniques-active versus passive-is highlighted from real-time data and long-term exposure assessment, including advances in sensor technology, data processing, and public awareness, to improve radon exposure evaluation techniques.

Beyond isotropic repulsion: Classical anisotropic repulsion by inclusion of p orbitals.

Accurate modeling of intermolecular repulsion is an integral component in force field development. Although repulsion can be explicitly calculated by applying the Pauli exclusion principle, this approach is computationally viable only for systems of limited sizes. Instead, it has previously been shown that repulsion can be reformulated in a "classical" picture: the Pauli exclusion principle prohibits electrons from occupying the same state, leading to a depletion of electronic charge between atoms, giving rise to an enhanced nuclear-nuclear electrostatic repulsion. This classical picture is called the isotropic S2/R approximation, where S is the overlap and R is the interatomic distance. This approximation accurately captures the repulsion of isotropic atoms such as noble gas dimers; however, a key deficiency is that it fails to capture the angular dependence of the repulsion of anisotropic molecules. To include directionality, the wave function must at least be a linear combination of s and p orbitals. We derive a new anisotropic S2/R repulsion model through the inclusion of the anisotropic p orbital term in the total wave function. Because repulsion is pairwise and decays rapidly, it can be truncated at a short range, making it amenable for efficient calculation of energy and forces in complex biomolecular systems. We present a parameterization of the S101 dimer database against the abinitio benchmark symmetry-adapted perturbation theory, which yields an rms error of only 0.9 kcal/mol. The importance of the anisotropic term is demonstrated through angular scans of water-water dimers and dimers involving halobenzene. Simulation of liquid water shows that the model can be computed efficiently for realistic system sizes.

Calculations of solubilities of pure noble gases and He–CO2/CH4/N2 gas mixtures in aqueous solutions with accurate thermodynamic models

Determining solubilities of pure noble gases and He–CO2/CH4/N2 gas mixtures in aqueous solutions is essential for various applications of noble gases in geological processes and for understanding the migration and accumulation of helium. This study developed two thermodynamic models for calculations of solubilities of five pure noble gases (i.e. He, Ne, Ar, Kr, and Xe) and He–CO2/CH4/N2 gas mixtures in water and in aqueous NaCl solution. The first model is constructed by extending the improved SAFT-LJ equation of state (EOS) to five binary H2O-noble gas systems and four ternary systems (i.e. H2O–He–NaCl, H2O–He–CO2, H2O–He–CH4, and H2O–He–N2). Both the non-ideality of aqueous phase and that of vapor phase of these systems were described using the improved SAFT-LJ EOS (φ-φ model). The second model is developed by modifying the gas solubility model proposed by Duan and his coworkers (one type of γ-φ model). The Pitzer theory was used to describe the non-ideality of aqueous phase and the improved SAFT-LJ EOS was used to describe the non-ideality of vapor phase. Both binary adjustable parameters of the improved SAFT-LJ EOS and parameters of the modified solubility model for pure gas were evaluated from experimental solubility data for pure gas. Both models are predictive for solubilities of gas mixtures since there is no need to evaluate their parameters from solubility data of gas mixtures.Comparisons of calculations of two models with experimental data show that both models can well represent solubilities and Henry's coefficients of five noble gases in pure water, as well as the solubility of He in aqueous NaCl solutions over a wide P-T range (273–600 K, 1–2000 bar for the solubility of He in water). The absolute average deviation of the improved SAFT-LJ EOS from experimental solubility data for five noble gases in pure water is 3.14% and that of the modified solubility model is 2.21%. Predictions of the improved SAFT-LJ EOS for Henry's coefficients for He in the He–CO2–H2O system are consistent with available experimental data. According to predictions of the improved SAFT-LJ EOS, Henry's coefficient for He in the He–CO2–H2O system is always lower than that in the He–H2O system at the same depth. Within 0–5 km depth, He solubility of He–CO2 gas mixture is much greater than that of pure He at the same depth and He partial pressure, He solubility of He–N2 mixture is a little greater than that of pure He, and He solubility of He–CH4 mixture is between that of He–CO2 mixture and that of He–N2 mixture. A computer program for calculations of solubilities of pure noble gases and He–CO2/CH4/N2 gas mixtures in pure water and in aqueous NaCl solutions can be obtained from the corresponding author via email.

Numerical simulation and experimental characterization of the TRIUMF-FEBIAD cathode temperature for optimizing the ion source performance

The FEBIAD ion source is routinely used to produce radioactive ions of halogens, molecules, and noble gases in several ISOL facilities worldwide. At TRIUMF, an extensive numerical and experimental campaign has been performed to fundamentally understand the source while improving its reliability and overall performance. Particularly, the cathode temperature has been studied by pyrometric measurements, Schottky analysis and numerical simulations to properly understand the electron emission driving the ionization. The temperature values found are consistent within the error bars and confirm the equivalence of the methodologies used. The findings can be used as part of a numerical ionization model for more realistic electron emission and the benchmarked thermal model can be used to propose novel and more robust geometries.

FFParam-v2.0: A Comprehensive Tool for CHARMM Additive and Drude Polarizable Force-Field Parameter Optimization and Validation.

Developing production quality CHARMM force-field (FF) parameters is a very detailed process involving a variety of calculations, many of which are specific for the molecule of interest. The first version of FFParam was developed as a standalone Python package designed for the optimization of electrostatic and bonded parameters of the CHARMM additive and polarizable Drude FFs by using quantum mechanical (QM) target data. The new version of FFParam has multiple new capabilities for FF parameter optimization and validation, with an emphasis on the ability to use condensed-phase target data in optimization. FFParam-v2 allows optimization of Lennard-Jones (LJ) parameters using potential energy scans of interactions between selected atoms in a molecule and noble gases, viz., He and Ne, and through condensed-phase calculations, from which experimental observables such as heats of vaporization and free energies of solvation may be obtained. This functionality serves as a gold standard for both optimizing parameters and validating the performance of the final parameters. A new bonded parameter optimization algorithm has been introduced to account for simultaneously optimizing multiple molecules sharing parameters. FFParam-v2 also supports the comparison of normal modes and the potential energy distribution of internal coordinates towards each normal mode obtained from QM and molecular mechanics calculations. Such comparison capability is vital to validate the balance among various bonded parameters that contribute to the complex normal modes of molecules. User interaction has been extended beyond the original graphical user interface to include command-line interface capabilities that allow for integration of FFParam in workflows, thereby facilitating the automation of parameter optimization. With these new functionalities, FFParam is a more comprehensive parameter optimization tool for both beginners and advanced users.

Imaging Rovibrational Excitation of Scattered YO Molecules in Inelastic Collisions with Kr and Ne.

Energy transfer between atoms and molecules is fundamental to many physical and chemical processes, and understanding the mechanisms and outcomes of energy transfer is crucial for various applications in physics and chemistry. Here, the rovibrational excitation of YO(X 2Σ+) molecules with the collision of Kr and Ne has been studied in the laser-ablation crossed beam and time-sliced ion velocity map imaging setup in combination with the resonance enhanced multiphoton ionization scheme. Significant changes in the angular distribution for different rovibrational excitations of YO molecules are observed with the collision of Kr. The sharp forward distribution for low rovibrational excitation of YO(v' = 0, 1) molecules suggest that the weak attractive potential between Kr and YO is dominant at large impact parameters. Comparatively, the strong sideway distribution for highly rovibrationally excited YO(v' = 1, 2, 3, and 5) is due to rainbow scattering from the stronger attractive potential of Kr···YO at relatively small impact parameters. The more isotropic angular distribution in the highly rovibrationally excited YO(v' = 11) indicates the formation of a short-lived complex. A change in the angular distribution of scattered YO with different rovibrational excitations was also observed in the collisions of Ne. For YO as a heteronuclear diatomic molecule, collisions of the Y- and the O-end of YO with rare gases would affect the contribution of inelastic processes at different impact parameters.

Permanent magnet ECR ion source and LEBT dipole for single-ended heavy ion ToF-ERDA facility

We present the status of the ion source and low energy beam transport prototyping for a single-ended heavy ion time-of-flight elastic recoil detection analysis equipment. The environmentally friendly concept is based on a permanent magnet ECR ion source and dipole magnet on a 500 kV platform without SF6 insulation, producing high charge state noble gas ion beams, e.g. 3–6 MeV argon. The ion fluxes of Ar6+–Ar12+ achieved with the CUBE-ECRIS permanent magnet minimum-B quadrupole ion source exceed 1-10 particle nA required for the low energy ToF-ERDA application. The CUBE-ECRIS can produce over 1 particle nA krypton and xenon beams up to charge states Kr19+ and Xe24+, which enables extending the scope of the ToF-ERDA application. The integration of an adjustable-field permanent magnet dipole into the CUBE-ECRIS test stand at the JYFL accelerator laboratory is described briefly.

Influence of post-welding heat treatment on microstructure and peculiarity of 10Cr9Mo1VNb boiler steel welded by hot wire TIG

Hot wire tungsten noble gas (HW-TIG) soldering tests are conducted on 10Cr9Mo1VNb boiler steel with multi-layer and multi-pass, and the soldered joints are subjected to post-weld heat treatment (PWHT) at different temperatures and times from 740°C to 790°C and 1 hour to 4 hours. The influence of PWHT on the microstructure and peculiarity of the joints are analyzed by using hardness, metallography, room temperature tensile testing, Charpy impact testing, SEM, and other experimental methods. The results show that the PWHT can transform the martensite formed in the welding process into tempered martensite, which can significantly improve the uniformity of the microstructure and peculiarity of each area of the joint. When subjected to heat treatment at 740°C, both strength and ductility improve with the increase of heat treatment time, while the plasticity gets a slight decrease. However, when subjected to heat treatment at 790°C, strength, plasticity, and ductility decrease with the increase of time, mainly due to the carbide coarsening such as M23C6 in the joint.

Transfer learning-assisted computational screening of metal-organic frameworks and covalent-organic frameworks for the separation of Xe/Kr noble gas

The adsorption separation of xenon/krypton (Xe/Kr) by porous materials has gained significant attention in industrial development. Metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) featuring permanent porosity, ultra-high surface area, and tunable pore size enable efficient separation of Xe/Kr, which promising structures can be identified by high-throughput computational screening and machine learning. However, the asymmetric development of the structure database between MOFs and other porous materials (including COFs) led to a data imbalance that challenged screening and machine learning for other porous materials, especially for computation-ready experimental (CoRE) databases. Transfer learning (TL) can address this issue by extracting the information from MOFs to improve generalization for other materials. In this work, geometric, energy, and chemical-based descriptors were obtained from MOFs and COFs to train TL models. It was demonstrated that TL with only 300 data sets of hypothetical COFs being used can produce satisfactory accuracy (R2 > 0.85) by predicting CoRE COFs based on CoRE MOFs. Furthermore, we conducted a feature importance analysis that suggested the energy descriptor plays a dominant role in predicting the Xe/Kr separation performance of the ensemble algorithm, whereas the chemical descriptor is an important descriptor for the deep neural network. This study provides an alternative transfer learning route to predict the Xe/Kr separation performance of nanoporous materials database with limited structures.

Presencia de eimerias en alpacas destetadas y alternativa de control sin ocasionar daño hepático

Considerando que la eimeriosis en alpacas es una enfermedad mortal, se plantea el objetivo de brindar una alternativa profiláctica en alpacas destetadas. Se evaluaron 30 alpacas del CICAS “La Raya” Cusco en Agosto 2022, distribuidas en 3 grupos de 10 alpacas, grupo1 (G1) 15 mg/kpv, grupo2 (G2) 22,5 mg/kpv de Toltrazuril y grupo3 (G3) control. Se realizó análisis coproparasitológico cualitativo de concentración por flotación y cuantitativo mediante método de McMaster modificado pre y post tratamiento; un posible daño hepático se evidenció mediante niveles séricos de alanina aminotransferasa (ALT) y aspartato aminotransferasa (AST). Como resultados, se identificaron eimerias en el 93,33% de alpacas destetadas, siendo más prevalente E. macusaniensis (63,33%). Así mismo, Toltrazuril a 22,5 mg/kpv controla parcialmente E. macusaniensis, mientras que a 15 y 22,5 mg/kpv controlan efectivamente a E. lamae a los 14 días post tratamiento; los niveles de AST y ALT en alpacas con 22,5 mg/kpv de Toltrazuril fueron 5,7 UI/L y 195,8 UI/L, respectivamente. En conclusión, Toltrazuril logra controlar a eimerias patógenas en alpacas, de manera parcial a E. macusaniensis, pero de forma efectiva a eimerias pequeñas como E. lamae sin alterar la función hepática en alpacas destetadas.

Presence of non-solar derived krypton and xenon unveiled by Chang'e-5 lunar soils

The extent of volatile elements on the surface and interior of the Moon remains a highly debated topic. Previous studies conducted on bulk lunar soil samples and solar wind samples collected by the Genesis mission indicate a discernible isotope mass- or non-mass-dependent fractionation of krypton and xenon. However, a detailed investigation of these processes is missing, particularly in determining the possible incorporation of cometary volatiles in the lunar regolith. New lunar soil samples returned by the Chang'e-5 mission provide a chance to answer these key questions. In this study, noble gas isotopes of nine subsamples from a Chang'e-5 scooped sample were analysed through stepwise-heating and total fusion laser extraction. The results reveal that a simple binary mixture of solar wind and cosmogenic components did not explain alone the isotopic composition of these samples. The Xe data shows insignificant amounts of atmospheric Xe and presents clear evidence of cometary contributions to the lunar regolith, with a significant depletion of 134,136Xe compared to that in the solar wind. Additionally, a meteoritic component is identified. Compared to the Apollo results, our findings further validate the theory of Earth's atmospheric escape, substantiate the plausibility of these exogenous admixtures to elucidate the isotopic fractionation mechanisms of Kr and Xe within the lunar regolith, and provide novel insights into long-term constancy in the solar wind composition.

Probing the electronic structure and ground state symmetry of gas phase C60+ via VUV photoionization and comparison with theory.

Recently, some of us reviewed and studied the photoionization dynamics of C60 that are of great interest to the astrochemical community as four of the diffuse interstellar bands (DIBs) have been assigned to electronic transitions in the C60+ cation. Our previous analysis of the threshold photoelectron spectrum (TPES) of C60 [Hrodmarsson et al., Phys. Chem. Chem. Phys. 22, 13880-13892 (2020)] appeared to give indication of D3d ground state symmetry, in contrast to theoretical predictions of D5d symmetry. Here, we revisit our original measurements taking account of a previous theoretical spectrum presented in the work of Manini et al., Phys. Rev. Lett. 91(19), 196402 (2003), obtained within a vibronic model parametrized on density functional theory/local-density approximation electronic structure involving all hg Jahn-Teller active modes, which couple to the 2Hu components of the ground state of the C60+ cation. By reanalyzing our measured TPES of the ground state of the C60 Buckminsterfullerene, we find a striking resemblance to the theoretical spectrum calculated in the work of Manini et al., Phys. Rev. Lett. 91(19), 196402 (2003), and we provide assignments for many of the hg modes. In order to obtain deeper insights into the temperature effects and possible anharmonicity effects, we provide complementary modeling of the photoelectron spectrum via classical molecular dynamics (MD) involving density functional based tight binding (DFTB) computations of the electronic structure for both C60 and C60+. The validity of the DFTB modeling is first checked vs the IR spectra of both species which are well established from IR spectroscopic studies. To aid the interpretation of our measured TPES and the comparisons to the abinitio spectrum we showcase the complementarity of utilizing MD calculations to predict the PES evolution at high temperatures expected in our experiment. The comparison with the theoretical spectrum presented in the work of Manini et al., Phys. Rev. Lett. 91(19), 196402 (2003), furthermore, provides further evidence for a D5d symmetric ground state of the C60+ cation in the gas phase, in complement to IR spectroscopy in frozen noble gas matrices. This not only allows us to assign the first adiabatic ionization transition and thus determine the ionization energy of C60 with greater accuracy than has been achieved at 7.598 ± 0.005eV, but we also assign the two lowest excited states (2E1u and 2E2u) which are visible in our TPES. Finally, we discuss the energetics of additional DIBs that could be assigned to C60+ in the future.

Pressure-induced formation of KrO2 from first-principles study

By first-principles study, we propose a hypothetical crystal (with space group P42/MNM) Krypton dioxide (KrO2) which might be synthesized at a pressure over 95[Formula: see text]GPa. At a pressure around 95[Formula: see text]GPa noticeable charge transfer from Kr atom to O atom occurs and chemical bonds are formed. Mechanism of this phenomena is analyzed using the electron-hopping mechanism. The formed Kr–O bond at high pressure can exist with retreated pressure down to 5[Formula: see text]GPa. The electron hopping mechanism might be applicable to the fabrication of other noble gas compounds.

Biogas Production from Organic Materials

Anaerobic digestion is a microbiologic process through which organic materials are broken down in oxygen absence and occurs in many environments. Now, biogas production is done in the reactors resistant to air penetration called digesters. A wide range of microorganisms is involved in the anaerobic process producing biogas and digestion as the final products. Biogas is a kind of flammable gas that contains methane, carbon dioxide, and a small amount of other rare elements and gases. Digestion of the decomposed materials rich in nutritional micros and macros plays the role of proper plant manure. Like other biofuels, biogas is also among the crucial priorities of energy and transportation policies made in Europe. In Europe, biogas is an inexpensive renewable energy source and neutral carbon dioxide that provides the field for processing and recycling many agricultural wastes and byproducts based on a sustainable and eco-friendly method. Biogas brings many socioeconomic advantages to society as a whole and also to investors.

Effect of gas components on the post-discharge temporal behavior of OH and O of a non-equilibrium atmospheric pressure plasma driven by nanosecond voltage pulses

OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma (NAPP), which plays an important role in applications such as plasma medicine. However, experimental studies on how the gas content affects the post-discharge temporal evolutions of OH and O in the noble gas ns-NAPP are very limited. In this work, the effect of the percentages of O2, N2, and H2O on the amounts of OH and O productions and their post-discharge temporal behaviors in ns-NAPP is investigated by laser-induced fluorescence (LIF) method. The results show that the productions of OH and O increase and then decrease with the increase of O2 percentage. Both OH and O densities reach their maximum when about 0.8% O2 is added. Further increase of the O2 concentration results in a decrease of the initial densities of both OH and O, and leads to their faster decay. The increase of N2 percentage also results in the increase and then decrease of the OH and O densities, but the change is smaller. Furthermore, when the H2O concentration is increased from 100 to 3000 ppm, the initial OH density increases slightly, but the OH density decays much faster, while the initial density of O decreases with the increase of the H2O concentration. After analysis, it is found that OH and O are mainly produced through electron collisional dissociation. O(1D) is critical for OH generation. O3 accelerates the consumption processes of OH and O at high O2 percentage. The addition of H2O in the NAPP considerably enhances the electronegativity, while it decreases the overall plasma reactivity, accelerates the decay of OH, and reduces the O atom density.