Depletion Factor Research Articles

A Study on Global Climate Mitigation and National Resource Management Based on the Green GDP Accounting Model

This article investigates the potential of Green GDP (GGDP) to replace conventional GDP as a global economic metric. By accounting for environmental degradation and natural resource depletion—factors typically excluded from traditional GDP calculations—GGDP offers a more comprehensive measure of long-term economic performance. Utilizing a linear regression model, this study examines the relationship between economic activity and climate change, with a focus on carbon emissions and water consumption. The findings reveal an inverse correlation between GGDP and rising global temperatures, suggesting GGDP’s potential to mitigate climate change by integrating the environmental costs of economic growth. A case study of China further illustrates how adopting GGDP could lead to improvements in air quality, more efficient resource management, and alignment with the country’s environmental objectives, including its commitments under the Paris Agreement. Although the transition from GDP to GGDP may face resistance, particularly in nations heavily reliant on fossil fuel consumption and resource exploitation are significant. This study underscores the necessity of incorporating environmental considerations into economic evaluations to foster a sustainable future, where economic growth can be achieved in harmony with ecological preservation. GGDP thus provides a more holistic and sustainable framework for assessing global economic performance.

Free gallium (III) determination with AGNES (Absence of Gradients and Nernstian Equilibrium Stripping)

Gallium is being extensively used in technological applications. Increasing emissions to the environment classify it as an emerging contaminant. Speciation information, such as the free gallium concentration, [Ga3+], is fundamental for understanding/predicting its bioavailability and potential toxicity to biota. In this work, [Ga3+] in aqueous solutions at pH2 and 3 has been measured with AGNES (Absence of Gradients and Nernstian Equilibrium Stripping). The deposition times to reach equilibrium, for a fixed accumulation factor or gain, were longer than those required with other metals such as Zn, Pb, Cd and In. This is attributed to the electrodic irreversibility of the couple Ga0/Ga3+ on the mercury electrode together with low concentrations of relatively poorly labile and/or poorly reversible (for the electrodic transfer) hydroxy complexes. When the AGNES-SCP variant was applied in the Hanging Mercury Drop Electrode with radius 141 μm, and the transition time was ≤10 s, the correction of the deposited mass with a depletion factor was essential. The speciation capacity of AGNES for Ga was evaluated with the phthalate ligand at pH 3 and the experimental results obtained were very similar to the theoretical results predicted with the stability constants in the NIST and Brown-Ekberg databases.

Vitamin B12 status in hospitalised cancer patients: Prevalence and clinical implications of depletion and hypervitaminosis

Background & AimsThe prevalence and clinical significance of vitamin B12 alterations in patients with cancer are poorly understood. We aimed to assess the prevalence and risk factors of vitamin B12 depletion or hypervitaminosis in patients with cancer. Methods: We retrospectively included hospitalised patients with cancer in 2017-2022. Plasma B12 levels were stratified as very low (VL, <200 pg/ml), low (L, 200-299 pg/ml), normal (N, 300-812 pg/ml), or high (H, ≥813 pg/ml). We collected demographic and several clinical data (e.g., comorbidities, nutritional status, ECOG-PS, cancer site and stage). Univariate and multivariate analyses for factors associated to the vitamin B12 status were fitted. Results: 788 patients (F/M ratio 1.05, median age 72 years, [25th, 75th percentiles 62, 78 years]) were included. Vitamin B12 was VL in 14.1%, L in 19.4%, N in 49.4%, and H in 17.1% cases. Vitamin B12 distribution increased significantly as function of ECOG-PS levels. Patients with breast cancer were characterized by the highest median B12 value, while colorectal cancer patients by the lowest. Vitamin B12 was also significantly higher in advanced compared to early-stage patients as well as in those who had liver failure. Multivariate analysis showed that the probability of H vs. VL B12 levels was significantly increased in patients with hypoproteinemia, hypo-prealbuminemia, and ECOG-PS≥2, and decreased in those with colorectal and gastric cancer. Conclusion: Vitamin B12 impairment is common in cancer patients. Increased vitamin B12 is associated with an impaired clinical status, while vitamin B12 depletion is more common in early-stage cancer and in elderly patients.

Magnitude and driving factors of boron depletion in agricultural soils

Magnitude and driving factors of boron depletion in agricultural soils

Galaxies with grains: unraveling dust evolution and extinction curves with hydrodynamical simulations

Dust in galaxies is an important tracer of galaxy properties and their evolution over time. The physical origin of the grain size distribution, the dust chemical composition, and, hence, the associated ultraviolet-to-optical extinctions in diverse galaxies remains elusive. To address this issue, we introduce a model for dust evolution in the RAMSES code for simulations of galaxies with a resolved multiphase interstellar medium. Dust is modelled as a fluid transported with the gas component, and is decomposed into two sizes, 5 nm and 0.1 μm, and two chemical compositions for carbonaceous and silicate grains. This dust model includes the growth of dust by accretion of elements from the gas phase and by the release of dust in stellar ejecta, the destruction by thermal sputtering, supernovae, and astration, and the exchange of dust mass between the two main populations of grain sizes by coagulation and shattering. Using a suite of isolated disc simulations with different masses and metallicities, the simulations can explore the role of these processes in shaping the key properties of dust in galaxies. The simulated Milky Way analogue reproduces the dust-to-metal mass ratio, depletion factors, size distribution and extinction curves of the Milky Way. Galaxies with lower metallicities reproduce the observed decrease in the dust-to-metal mass ratio with metallicity at around a few 0.1 Z⊙. This break in the dust-to-metal ratio corresponds to a galactic gas metallicity threshold that marks the transition from an ejecta-dominated to an accretion-dominated grain growth, and that is different for silicate and carbonaceous grains, with ≃0.1 Z⊙ and ≃0.5 Z⊙ respectively. This leads to more Magellanic Cloud-like extinction curves, i.e. with steeper slopes in the ultraviolet and a weaker bump feature at 2175 Å, in galaxies with lower masses and lower metallicities. Steeper slopes in these galaxies are caused by the combination of the higher efficiency of gas accretion by silicate relative to carbonaceous grains and by the low rates of coagulation that preserves the amount of small silicate grains. Weak bumps are due to the overall inefficient accretion growth of carbonaceous dust at low metallicity, whose growth is mostly supported by the release of large grains in SN ejecta. We also show that the formation of CO molecules is a key component to limit the ability of carbonaceous dust to grow, in particular in low-metallicity gas-rich galaxies.

C/O Ratios and the Formation of Wide-separation Exoplanets

The gas and solid-state C/O ratios provide context to potentially link the atmospheric composition of planets to that of the natal disk. We provide a synthesis of extant estimates of the gaseous C/O and C/H ratios in planet-forming disks obtained primarily through analysis of Atacama Large Millimeter/submillimeter Array observations. These estimates are compared to atmospheric abundances of wide-separation (>10 au) gas giants. The resolved disk gas C/O ratios, from seven systems, generally exhibit C/O ≥ 1 with subsolar, or depleted, carbon content. In contrast, wide-separation gas giants have atmospheric C/O ratios that cluster near or slightly above the presumed stellar value with a range of elemental C/H. From the existing disk composition, we infer that the solid-state millimeter/centimeter-sized pebbles have a total C/O ratio (solid cores and ices) that is solar (stellar) in content. We explore simple models that reconstruct the exoplanet atmospheric composition from the disk, while accounting for silicate cloud formation in the planet atmosphere. If wide-separation planets formed via the core-accretion mechanism, they must acquire their metals from pebble or planetesimal accretion. Further, the dispersion in giant planet C/H content is best matched by a disk composition with modest and variable factors of carbon depletion. An origin of the wide-separation gas giants via gravitational instability cannot be ruled out, as stellar C/O ratios should natively form in this scenario. However, the variation in planet metallicity with a stellar C/O ratio potentially presents challenges to these models.

Accretion and Uneven Depletion of the Main Asteroid Belt

The main asteroid belt (MAB) is known to be primarily composed of objects from two distinct taxonomic classes, generically defined here as S- and C-complex. The former probably originated from the inner solar system (interior to Jupiter’s orbit), while the latter probably originated from the outer solar system. Following this definition, (4) Vesta, a V-type residing in the inner MAB (a < 2.5 au), is the sole D > 500 km object akin to the S-complex that potentially formed in situ. This provides a useful constraint on the number of D > 500 km bodies that could have formed, or grown, within the primordial MAB. In this work, we numerically simulate the accretion of objects in the MAB region during the time when gas in the protoplanetary disk still existed while assuming different MAB primordial masses. We then account for the depletion of that population happening after gas disk dispersal. In our analysis, we subdivided the MAB into five subregions and showed that the depletion factor varies throughout the MAB. This results in uneven radial- and size-dependent depletion of the MAB. We show that the MAB primordial mass has to be ≲2.14 × 10−3 M ⊕. Larger primordial masses would lead to the accretion of tens to thousands of S-complex objects with D > 500 km in the MAB. Such large objects would survive depletion even in the outer subregions (a > 2.5 au), thus being inconsistent with observations. Our results also indicate that S-complex objects with D > 200–300 km, including (4) Vesta, are likely to be terrestrial planetesimals implanted into the MAB rather than formed in situ.

Parsec-scale cosmic-ray ionisation rate in Orion

Cosmic rays are a key component of the interstellar medium because they regulate the dynamics and chemical processes in the densest and coldest regions of molecular clouds. Still, the cosmic-ray ionisation rate of H$_2$ (crir ) is one of the most debated parameters characterising molecular clouds because of the uncertainties in the adopted chemical networks and analysis techniques. This work aims to homogeneously estimate the crir at parsec scales towards the Orion Molecular Clouds OMC-2 and OMC-3. We explore the change in crir across a whole star-forming region by probing a range of column densities taht has never been explored before. The significant increase in statistics obtained by studying an entire region allows us to place stronger constraints on the range of crir values and exploit its connection with the physical properties of the interstellar medium. The most recent crir estimates are based on o$-$H$_2$D$^+$, which is a direct product of the interaction between cosmic rays and H$_2$ in cold clouds. Since observations of o$-$H$_2$D$^+$ are challenging, we proxy its abundance through CO depletion by employing C18O (2$-$1) observations towards OMC-2 and OMC-3, taking advantage of the existing correlation between the two parameters. Using additional observations of HCO$^+$ (1$-$0) and DCO$^+$ (3$-$2), we determine the deuteration fraction, and we finally derive the map of crir in these two regions. The C18O depletion correlates with both the total column density of H$_2$ and the N$_2$H$^+$ emission across OMC-2 and OMC-3. The obtained depletion factors and deuteration fractions are consistent with previous values obtained in low- and high-mass star-forming regions. These two parameters additionally show a positive correlation in the coldest fields of our maps. We derive cosmic-ray ionisation rates of $ $ s$^ $. These values agree well with previous estimates based on o$-$H$_2$D$^+$ observations. The crir also shows a functional dependence on the column density of H$_2$ across a full order of magnitude ($ $ cm$^ $). The estimated values of crir decrease overall for increasing $N( H_2 $), as predicted by theoretical models. The results delivered by our approach are comparable with theoretical predictions and previous independent studies. This confirms the robustness of the analytical framework and promotes CO depletion as a viable proxy of o$-$H$_2$D$^+$. We also explore the main limitations of the method by varying the physical size of the gas crossed by the cosmic rays (i.e. the path length). By employing a path length obtained from low-resolution observations, we recover values of the crir that are well below any existing theoretical and observational prediction. This discrepancy highlights the need for interferometric observations in order to reliably constrain the crir at parsec scales as well.

Analysis of Government Efforts to Handle Declining Petroleum Yields in Indonesia

All existing innovations continue to be developed by both the government and the community to obtain future savings frHom petroleum products for the next year. The purpose of this research is to analyze how the government innovates in maintaining the limitations and availability of petroleum materials in Indonesia and the impact on how to handle the issue of petroleum problems. The discussion in this article covers the factors of depletion of Indonesia's petroleum reserves, how innovations are carried out, and the impacts they have. This analysis refers to electronic journals that can be accounted for based on discussions of the government's efforts to deal with the decline in petroleum output in Indonesia. The methodology used is a quantitative descriptive method to analyze the issues to be discussed. The data obtained came from journals using skill-free listening (SLBB) and note-taking techniques. Researchers understand the contents of the journals obtained and the results are in the form of notes with correct accountability. It is hoped that the analysis in this article will be able to increase insight and understanding, especially regarding innovations from the government and the people in dealing with the decline in petroleum output, and be able to provide a guide for readers to criticize the results of this article.

Reproduction-mobility trade-off in rock-paper-scissors models in changing environmental conditions

We investigate a tritrophic system in which organisms’ energy depletion, resulting from failed selection attempts, leads to a partial loss of capacity to win the cyclic spatial game. The energy required to maintain optimal organism fitness may be impacted by changes in environmental conditions, increasing the death risk due to accelerated deterioration of health. We simulate the evolutionary behavioural strategy performed by individuals of one species, which consists in balancing efforts dedicated to reproduction and mobility to minimise the chances of death by lack of energy. We show that the unevenness introduced by the trade-off strategy unbalances the rock-paper-scissors model, with the predominant species profiting from enemies’ lower birth rate. Quantifying the spatial patterns, we demonstrate that the characteristic length scale of single-species domains decreases as energy loss accelerates due to environmental changes. The erosion in the spatial patterns provoked by the reproduction-mobility trade-off benefits biodiversity, with coexistence probability rising for faster energy depletion and higher trade-off factors. The findings have implications for ecologists seeking to understand the impact of survival behaviour on biodiversity promotion.

IMPLEMENTING A DATA-DRIVEN SOIL WATER BALANCE APPROACH FOR PRECISION IRRIGATION IN PENINSULAR MALAYSIA

Optimizing irrigation practices is crucial to ensure that plants receive the correct amount of water while minimizing inefficiencies resulting from deep percolation or drainage. This article introduces a smartphone application that accurately predicts the timing and duration of irrigation for various crops in Malaysia. The app uses locally calibrated crop coefficients, Maximum Allowed Depletion factors, and local formulas to calculate effective rainfall and evapotranspiration. This allows us to identify the most efficient irrigation cycle for each selected crop in Peninsular Malaysia. The application is a pioneering tool that considers meteorological conditions, precipitation, and plant water stress to determine the most efficient irrigation cycles for crops grown in the selected area. Additionally, this smartphone application is the first tool capable of calculating effective rainfall for any designated geographical area in Peninsular Malaysia. This represents a significant advancement for farmers, offering them cutting-edge precision farming tools that enhance the efficiency of their irrigation cycle. This program contributes to reducing water waste and enhancing crop yields by providing precise estimations of irrigation frequency and runtime. By applying the same approach, this app could also be extended to other Southeast Asian countries.

Monitoring HIV-1 Nuclear Import Kinetics Using a Chemically Induced Nuclear Pore Blockade Assay.

To integrate with host chromatin and establish a productive infection, HIV-1 must translocate the viral Ribonucleoprotein (RNP) complex through the nuclear pore complex (NPC). Current assay to measure HIV-1 nuclear import relies on a transient byproduct of HIV-1 integration failure called 2-LTR circles. However, 2-LTR circles require complete or near-complete reverse transcription and association with the non-homologous end joining (NHEJ) machinery in the nucleus, which can complicate interpretation of 2-LTR circle formation as a measure of nuclear import kinetics. Here, we describe an approach to measure nuclear import of infectious HIV-1 particles. This involves chemically induced dimerization of Nup62, a central FG containing nucleoporin. Using this technique, nuclear import of infectious particles can be monitored in both primary and cell culture models. In response to host factor depletion or restriction factors, changes in HIV-1 nuclear import can be effectively measured using the nuclear import kinetics (NIK) assay.

A study on comparative environmental impact assessment of thermochemical cycles and steam methane reforming processes for hydrogen production processes

Alternative energy sources are extensively studied to meet the increasing energy demand. To address rising energy demand, hydrogen generation through environmentally friendly sources are explored, and new technologies are now needed badly. Hydrogen can be generated using fossil fuels, nuclear energy and renewable energy. Most of the hydrogen is still produced using fossil-based fuels, which increases the amount of greenhouse gases. This study examines the life-cycle impact of three alternative hydrogen-generating processes. The solar-based hybrid sulfur (HyS) thermochemical cycle, the nuclear-based HyS thermochemical cycle, and steam methane reforming (SMR) are all considered, and the environmental consequences of the SMR and thermochemical facilities are evaluated. The CML-IA impact categories are used to analyze environmental impacts. The SimaPro 9.2, a modeling software package developed for the detailed descriptions and simulations of complex products, services and processes, is used to perform the life cycle impact assessment (LCIA). This study aims to determine the best environmentally friendly option for hydrogen production by analyzing and comparing its environmental implications. Different impact categories namely global warming potential (GWP), human toxicity potential (HTP), ozone layer depletion (ODP), abiotic depletion factor (ADF), and acidification potential (AP), are examined based on the CML-IA impact classifications. The results show that the solar-based HyS cycle options yield the lowest global warming potential, abiotic depletion, acidification potential, ozone layer depletion, and human toxicity potential values were 1.04 kg CO2 eq/kg H2, 0.013 kg Sb eq/kg H2, 0.0027 kg SO2 eq/kg H2, 0.0007 kg CFC-11 eq/kg H2, and 0.27 kg 1,4-DB-eq/kg H2, respectively. The environmental impact results further show that the solar-powered hydrogen generation is a promising approach for cleaner hydrogen generation.

3D global simulations of accretion onto gap-opening planets: implications for circumplanetary disc structures and accretion rates

ABSTRACT We perform a series of 3D simulations to study the accretion of giant planet embedded in protoplanetary discs (PPDs) over gap-opening time-scales. We find that the accretion mass flux mainly comes from the intermediate latitude above the disc mid-plane. The circumplanetary disc (CPD) for a super-thermal planet is rotation-supported up to ∼20–30 per cent of the planet Hill radius. While both mass inflow and outflow exists in the CPD mid-plane, the overall trend is an outflow that forms a meridional circulation with high-latitude inflows. We confirm the absence of accretion outburst from disc eccentricity excited by massive planets in our 3D simulations, contrary to the consensus of previous 2D simulations. This suggests the necessity of 3D simulations of accretion even for super-Jupiters. The accretion rates of planets measured in a steady state can be decomposed into the ‘geometric’ and ‘density depletion’ factors. Through an extensive parameter survey, we identify a power-law scaling for the geometric factor $\propto q_{\rm th}^{2/3}$ for super-thermal planets (qth being the thermal mass ratio), which transform to $\propto q_{\rm th}^{2}$ for less massive cases. The density depletion factor is limited by the disc accretion rate for mildly super-thermal planets and by gap-opening for highly super-thermal ones. Moderate planetary eccentricities can enhance the accretion rates by a factor of 2–3 by making the gap shallower, but it does not impact the flow geometry. We have applied our simulations results to accreting protoplanet system PDS 70 and can satisfactorily explain the accretion rate and CPD size in observations.

Evolution of Chemistry in the envelope of HOt corinoS (ECHOS)

Context. Within the project Evolution of Chemistry in the envelope of HOt corinoS (ECHOS), we present a study of sulphur chemistry in the envelope of the Class 0 source B 335 through observations in the spectral range λ = 7, 3, and 2 mm. Aims. Our goal is to characterise the sulphur chemistry in this isolated protostellar source and compare it with other Class 0 objects to determine the environmental and evolutionary effects on the sulphur chemistry in these young sources. Methods. We have modelled observations and computed column densities assuming local thermodynamic equilibrium and large velocity gradient approximation. We have also used the code Nautilus to study the time evolution of sulphur species, as well as of several sulphur molecular ratios. Results. We have detected 20 sulphur species in B 335 with a total gas-phase S abundance similar to that found in the envelopes of other Class 0 objects, but with significant differences in the abundances between sulphur carbon chains and sulphur molecules containing oxygen and nitrogen. Our results highlight the nature of B 335 as a source especially rich in sulphur carbon chains unlike other Class 0 sources. The low presence or absence of some molecules, such as SO and SO+, suggests a chemistry not particularly influenced by shocks. We, however, detect a large presence of HCS+ that, together with the low rotational temperatures obtained for all the S species (&lt;15 K), reveals the moderate or low density of the envelope of B 335. Model results also show the large influence of the cosmic ray ionisation rate and density variations on the abundances of some S species (e.g. SO, SO2, CCS, and CCCS) with differences of up to ~4 orders of magnitude. We also find that observations are better reproduced by models with a sulphur depletion factor of 10 with respect to the sulphur cosmic elemental abundance. Conclusions. The comparison between our model and observational results for B 335 reveals an age of 104 &lt; t &lt; 105 yr, which high-lights the particularly early evolutionary stage of this source. B 335 presents a different chemistry compared to other young protostars that have formed in dense molecular clouds, which could be the result of accretion of surrounding material from the diffuse cloud onto the protostellar envelope of B 335. In addition, the theoretical analysis and comparison with observations of the SO2/C2S, SO/CS, and HCS+/CS ratios within a sample of prestellar cores and Class 0 objects show that they could be used as good chemical evolutionary indicators of the prestellar to protostellar transition.

Effects of irradiation on the insolubility of sodium fast reactor (U,Pu)O2 mixed oxide with a very high amount of plutonium

Sodium fast nuclear reactors might operate with MOX fuels containing up to 45% of plutonium, nevertheless, the reprocessability of spent nuclear fuel is sparsely investigated in the literature for plutonium contents higher than 30%. The dissolution step is a critical stage for MOX fuels since plutonium oxide exhibits a much slower dissolution kinetics as compared to uranium oxide. In particular, many authors suggested a significant change in the dissolution behavior of mixed oxides for plutonium contents between 30% and 50%. In this paper, the dissolution tests of unirradiated and irradiated CAPRA pellets with an initial plutonium content of 45% is described. Up to our knowledge, this is the first dissolution test reported in the literature with such high plutonium content in irradiated nuclear fuel. The fresh unirradiated pellets appears almost insoluble due to a very slow dissolution kinetics. Although the insolubility remains high after irradiation, a beneficial effect of irradiation on the dissolution behavior is observed with a depletion factor of five. The dissolution rates observed are very consistent with previous studies reported in the literature. The results show that complementary steps such as fuel pre-treatment or depletion steps should be considered in order to recycle spent nuclear fuel highly enriched in plutonium.

Climate Change and Ecologically Vulnerable Farming in Punjab: Some Highlights

The economic and technological growth in the last quarter of the 20th century and the beginning of the 21st century resulted in a drastic change in the climate (extreme weather conditions for the sustainability of human life on the earth). The updated report of CoP-25 (meeting of Parties), which was held on 3rd December 2019 in Madrid (Spain) used the term “climate emergency” instead of “climate change”. It was a warning for all the developing and developed countries, which depended heavily upon agriculture. The present study highlights some of the global climatic issues which affected the anthropological development in Punjab. This state has been regarded as the backbone of the Indian economy and is also known as the food basket of India. The cropping pattern is changing from diversification to specialisation. The farmers of the Punjab region focus only on rice-wheat cropping patterns. The major factors of resource depletion, particularly in Punjab, are land and water. The problem of food security and environmental degradation is increasing day by day.

NAMPT/SIRT1 Expression Levels in White Blood Cells Differentiate the Different Rheumatoid Arthritis Subsets: An Inspiration from Traditional Chinese Medicine.

Rheumatoid arthritis (RA) patients are prone to developing different metabolic complications. Traditional Chinese Medicine attributes this uncertainty to varied syndrome types. We retrospectively analyzed some serological indicators of active RA patients and healthy individuals. Randomly selected RA patients were divided into three groups according to NAMPT and SIRT1 expression levels in white blood cells (WBCs). Their disease severity and metabolic status were compared. Representative blood samples were subjected to a UPLC-MS/MS-based metabolomics analysis. Different human WBCs were treated with oleic acid and palmitic acid in vitro. The results indicated that blood glucose and lipid levels were decreased in RA patients, but their decrease was not in accordance with disease severity. Nutrients in the patients highly expressing SIRT1 were well preserved, with the lowest levels of RF and β-CTX and the highest levels of adiponectin and resistin. Most of them exhibited cold symptoms. When SIRT1 deficiency was obvious, lipid depletion became evident, irrespective of expression levels of NAMPT. Simultaneous high-expression of SIRT1 and NAMPT coincided with the increase in production of lactic acid and the prevalence of hot symptoms. Despite the low levels of IL-6, joint injuries were severe. The corresponding WBCs were especially sensitive to fatty acids anti-inflammatory treatments. The levels of CCL27, CCL11, CCL5, AKP, CRP and ESR were similar among all the groups. NAMPT overexpression is a risk factor for joint injuries and nutrient depletion in RA. Supplementation with lipids would exert beneficial effects on these RA patients. Its aftermath would cause even severe inflammation. Contrarily, SIRT1 up-regulation restrains inflammation and lipid depletion.

Gas phase Elemental abundances in Molecular cloudS (GEMS)

Context. Carbon monosulphide (CS) is among the few sulphur-bearing species that have been widely observed in all environments, including in the most extreme, such as diffuse clouds. Moreover, CS has been widely used as a tracer of the gas density in the interstellar medium in our Galaxy and external galaxies. Therefore, a complete understanding of its chemistry in all environments is of paramount importance for the study of interstellar matter. Aims. Our group is revising the rates of the main formation and destruction mechanisms of CS. In particular, we focus on those involving open-shell species for which the classical capture model might not be sufficiently accurate. In this paper, we revise the rates of reactions CH + S → CS + H and C2 + S → CS + C. These reactions are important CS formation routes in some environments such as dark and diffuse warm gas. Methods. We performed ab initio calculations to characterize the main features of all the electronic states correlating to the open shell reactants. For CH+S, we calculated the full potential energy surfaces (PESs) for the lowest doublet states and the reaction rate constant with a quasi-classical method. For C2+S, the reaction can only take place through the three lower triplet states, which all present deep insertion wells. A detailed study of the long-range interactions for these triplet states allowed us to apply a statistic adiabatic method to determine the rate constants. Results. Our detailed theoretical study of the CH + S → CS + H reaction shows that its rate is nearly independent of the temperature in a range of 10–500 K, with an almost constant value of 5.5 × 10−11 cm3 s−1 at temperatures above 100 K. This is a factor of about 2–3 lower than the value obtained with the capture model. The rate of the reaction C2 + S → CS + C does depend on the temperature, and takes values close to 2.0 × 10−10 cm3 s−1 at low temperatures, which increase to ~ 5.0 × 10−10 cm3 s−1 for temperatures higher than 200 K. In this case, our detailed modeling - taking into account the electronic and spin states – provides a rate that is higher than the one currently used by factor of approximately 2. Conclusions. These reactions were selected based on their inclusion of open-shell species with many degenerate electronic states, and, unexpectedly, the results obtained in the present detailed calculations provide values that differ by a factor of about 2–3 from the simpler classical capture method. We updated the sulphur network with these new rates and compare our results in the prototypical case of TMC1 (CP). We find a reasonable agreement between model predictions and observations with a sulphur depletion factor of 20 relative to the sulphur cosmic abundance. However, it is not possible to fit the abundances of all sulphur-bearing molecules better than a factor of 10 at the same chemical time.

STUDY OF SAND PRODUCTION STAGES IN SHALLOW OIL FIELDS

This article presents the High Pressure Consolidation System (HPСS) and a new experimental method for studying sand behavior in weak sandstone reservoirs. Under laboratory conditions, geostress conditions during the process of rock sedimentation, perforation, and sand production were replicated using a large artificial sample. A comprehensive investigation of sand production phenomena was conducted, where rock and pore pressures were fully controlled throughout the experiment using a computer. The HPCS also allows the study of single-phase and multiphase flow behavior in porous media at realistic reservoir pressures to model various well exploitation scenarios, such as implementing different depletion factors and water-oil ratios.