Loss Processes Research Articles

Bose-Einstein condensation of non-ground-state caesium atoms

Bose-Einstein condensates of ultracold atoms serve as low-entropy sources for a multitude of quantum-science applications, ranging from quantum simulation and quantum many-body physics to proof-of-principle experiments in quantum metrology and quantum computing. For stability reasons, in the majority of cases the energetically lowest-lying atomic spin state is used. Here, we report the Bose-Einstein condensation of caesium atoms in the Zeeman-excited mf = 2 state, realizing a non-ground-state Bose-Einstein condensate with tunable interactions and tunable loss. We identify two regions of magnetic field in which the two-body relaxation rate is low enough that condensation is possible. We characterize the phase transition and quantify the loss processes, finding unusually high three-body losses in one of the two regions. Our results open up new possibilities for the mixing of quantum-degenerate gases, for polaron and impurity physics, and in particular for the study of impurity transport in strongly correlated one-dimensional quantum wires.

Loss, gain and choice difficulty in gambling patients: Neural and behavioural processes.

Impaired decision-making is often displayed by individuals suffering from gambling disorder (GD). Since there are a variety of different phenomena influencing decision-making, we focused in this study on the effects of GD on neural and behavioural processes related to loss aversion and choice difficulty. Behavioural responses as well as brain images of 23 patients with GD and 20 controls were recorded while they completed a mixed gambles task, where they had to decide to either accept or reject gambles with different amounts of potential gain and loss. We found no behavioural loss aversion in either group and no group differences regarding loss and gain-related choice behaviour, but there was a weaker relation between choice difficulty and decision time in patients with GD. Similarly, we observed no group differences in processing of losses or gains, but choice difficulty was weaker associated with brain activity in the right anterior insula and anterior cingulate cortex in patients with GD. Our results showed for the first time the effects of GD on neural processes related to choice difficulty. In addition, our findings on choice difficulty give new insights on the psychopathology of GD and on neural processes related to impaired decision-making in GD.

Prompt extinction of bump-on-tail energy spectra for radiation belt electron phase space density

The bump-on-tail electron flux energy spectral distributions in the Earth's radiation belt are widely observed and have been proven to be generated by plasmaspheric hiss-led wave–particle interactions. Here, we report and discuss the prompt disappearance of them induced by the high solar wind dynamic pressure (Pdyn) combined with substorms on 12–13 March 2014. To remove the potential adiabatic influence, the electron fluxes are all converted to phase space density in the TS04 geomagnetic coordinate. Immediately after the Pdyn reached its maximum accompanied by the intensifying of substorms, the initial bump-on-tail spectra of the phase space density at L* (the third adiabatic invariant) from 3.8 to 4.4 were destroyed and rapidly smoothed to the exponential distributions, with a distinct ascent for lower energy electrons and a sharp decline for higher energy electrons. The balance line between the source and loss processes was located at μ = 50–200 MeV/G (μ is the first adiabatic invariant), which is sensitive to the spatial location. Further investigation of the temporal evolution of the phase space density along with L* and the plasma wave distributions provided evidence that the loss processes dominated at higher L* for electrons at μ ≳ 100 MeV/G, while the source processes became stronger at lower L* for electrons at μ ≲ 10 MeV/G. Our study provides new insight into the rapid change of the radiation belt electron spectral types in response to solar wind disturbances, which could be fully considered in further radiation belt particle modeling.

Presheath-like structures and effusive particle losses for biased probes at and near I–V electron saturation

A theory for presheath-like structures near probes biased at and above the plasma potential is developed for collisionless plasmas with an electron-neutral mean free path on the order of the chamber scale. The theory predicts presheath-like perturbations to the plasma that result from the free streaming of electrons and an effusion loss process from the chamber at the electrode. For these situations, a loss-cone-like velocity distribution function for electrons is predicted where the loss angle of the depletion region corresponds to the angular size of the electrode at a specified distance. The angle of the loss cone becomes 180° at the sheath edge. In comparison with a previous collisional electron presheath model that required electrons satisfy a Bohm criterion at the sheath edge [Scheiner et al., Phys. Plasmas 22, 123520 (2015)], the present work suggests that no such condition is needed for collisionless low pressure plasmas in the ≲10 mTorr range. The theory predicts the generation of a density depletion of roughly 0.5ne and an electron velocity moment of tens of percent of the electron thermal speed by the sheath edge in a presheath with a potential drop of less than Ti/e. The range of this presheath perturbation is determined by the electrode geometry instead of the collisional mean free path. These predictions are tested against previously published particle in cell simulations and are found to be in good agreement.

The Relationship Between Electron Precipitation and the Population of Trapped Electrons in LEO: New Evidence Supporting a Natural Limit to the Flux of Energetic Electrons

AbstractEnergetic particle precipitation into the atmosphere has been identified as a key loss process for electrons in the Earth's outer radiation belt region. However, direct measurements of the electron flux precipitating into the atmosphere are challenging from high altitude low inclination spacecraft, such as the Van Allen Probes, due to the small angular size of the loss cone along the orbital path of these high‐altitude spacecraft. Here we use data from the Polar Orbiting Environmental Satellites (POES)/Space Environment Monitor in low‐Earth orbit to assess the relationship between the trapped and precipitating electron flux in integral energy channels >30, >100, and >300 keV. Our results highlight that there is a strong non‐linear relationship between the flux of trapped and precipitating electrons, with the ratio of precipitating to trapped flux only becoming significantly enhanced once the trapped flux reaches a critical level. This transition from low to high levels of precipitation is consistent with the theory proposed by Kennel and Petschek (K‐P) (1966) https://doi.org/10.1029/JZ071i001p00001, whereby intense chorus waves are excited and trigger pitch angle diffusion, resulting in energetic particle precipitation and limiting the trapped flux. Using electron flux data from POES and chorus wave data from the Van Allen Probes, we further test the observations against predictions from the K‐P theory. A particle tracing model is also utilized to illustrate a direct link between the drift paths of injected electrons, the occurrence of chorus waves and the spatial distribution of strong electron precipitation into the atmosphere at different energies.

Some loss factors and processing methods of dried fishes used in the Sahelian domain of Cameroon

Fish is an important source of protein, minerals and essential fatty acids for human nutrition. To ensure its permanent availability, this highly perishable commodity is processed and stored. However, during storage, dry fishes suffer significant quantitative and qualitative losses due to the lack of efficient pest control methods and preservative processes. An intensive interview survey was conducted with 175 dry fish sellers in markets and processors' families in the Logone basin from 2020 to 2021 to identify the causes of losses and the usual tools used to limit them. It was found that losses of dry fish start during handling and transport where inadequate packaging breaks the dry fish. In addition, fishes are attacked by insect pests, losses depend on fish species and climate. In the Logone basin, 14 species of fish are caught and processed, the most represented species are Cyprinus carpio Linnaeus 1758 with 24.49%, Clarias gariepinus Burchell 1822 with 21.26% and Brevimyrus niger Günther 1866 with 15.40%. Their major pests are insects (53%), rodents (28%) and fungi (9%). Moreover, during handling/transport, 10% are lost. The insects identified are from the family of Cleridae and Dermestidae. Cleridae predominate in the surveyed areas with 67.76% against 32.23% of Dermestidae. Four species are identified: Dermestes maculatus, Dermestes frischii, Dermestes ater and Necrobia rufipes. Moreover, to protect their fish against these insect pests, stakeholders use industrial chemicals, generally sold as plant protection products, and local products derived from biodiversity local. The most popular chemical pesticide applied on dried fish has dichlorvos as active ingredient (83%). The most used are DD FORCE (48.51%) and PRIME SHI (16.26%), at the level of sellers and processors. It is an extremely hazardous pesticide, damaging health of consumers and polluting the environment. It would be necessary to consider the use of bio insecticides for the protection of the dried fish against pests and for the health safety of consumers. Key words: Dry fish, insect pests, storage, pesticides, Cameroon, Logone basin

Suppressing dipolar relaxation in thin layers of dysprosium atoms

The dipolar interaction can be attractive or repulsive, depending on the position and orientation of the dipoles. Constraining atoms to a plane with their magnetic moment aligned perpendicularly leads to a largely side-by-side repulsion and generates a dipolar barrier which prevents atoms from approaching each other. We show experimentally and theoretically how this can suppress dipolar relaxation, the dominant loss process in spin mixtures of highly magnetic atoms. Using dysprosium, we observe an order of magnitude reduction in the relaxation rate constant, and another factor of ten is within reach based on the models which we have validated with our experimental study. The loss suppression opens up many new possibilities for quantum simulations with spin mixtures of highly magnetic atoms.

Experimental and statistical models moisture release of the mixture treated with reagents raw sludge and compacted active sludge

The technology of changing the resistivity of a mixture of raw sludge and compacted activated sludge taken after the sludge pumping station of urban sewage treatment plants by treating the sludge with aluminum sulfate and polyacrylamide (PAA) in doses from 0 to 300 mg/dm3 has been tested. The degree of influence of each reagent on the process of dehydration of the sediment under study has been established. It has been shown that PAA has about 2.0 times greater effect on the process of moisture loss than Al2(SO4)3 at reagent doses from 0 to 200 mg/dm3 and about 1.5 times – at doses from 100 to 300 mg/dm3. Mathematical models of the dependence of the change in the resistivity of the sediment on the amount of Al2(SO4)3 and PAA introduced into it are obtained. Mathematical models are also presented in graphical form (isolines). The optimal doses of coagulant and flocculant for chemical treatment of the studied sewage sludge were determined.

Effects of the Charge Density of Nanopapers Based on Carboxymethylated Cellulose Nanofibrils Investigated by Complementary Techniques.

Cellulose nanofibrils (CNFs) with different charge densities were prepared and investigated by a combination of different complementary techniques sensitive to the structure and molecular dynamics of the system. The morphology of the materials was investigated by scanning electron microscopy (SEM) and X-ray scattering (SAXS/WAXS). The latter measurements were quantitatively analyzed yielding to molecular parameters in dependence of the charge density like the diameter of the fibrils, the distance between the fibrils, and the dimension of bundles of nanofibrils, including pores. The influence of water on the properties and the charge density is studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and broadband dielectric spectroscopy. The TGA measurements reveal two mass loss processes. The one at lower temperatures was related to the loss of water, and the second process at higher temperatures was related to the chemical decomposition. The resulting char yield could be correlated to the distance between the microfibrils. The DSC investigation for hydrated CNFs revealed three glass transitions due to the cellulose segments surrounded by water molecules in different states. In the second heating scan, only one broad glass transition is observed. The dielectric spectra reveal two relaxation processes. At low temperatures or higher frequencies, the β-relaxation is observed, which is assigned to localized fluctuation of the glycosidic linkage. At higher temperatures and lower frequencies, the α-relaxation takes places. This relaxation is due to cooperative fluctuations in the cellulose segments. Both processes were quantitatively analyzed. The obtained parameters such as the relaxation rates were related to both the morphological data, the charge density, and the content of water for the first time.

Differences in sediment provenance from rainfall and snowmelt erosion in the Mollisol region of Northeast China

AbstractDifferences in erosion patterns inevitably lead to different soil loss processes. However, the differences in sediment sources between rainfall and snowmelt erosion are not well studied. To address this gap, a study was conducted in a small agricultural catchment (3.5 km2) using the fingerprinting technique to quantify the various sources contributing to sediment, as well as determine the magnitude of sediment total nitrogen (TN), total phosphorus (TP), total potassium (TK) and soil organic matter (SOM) loads from three sources (cultivated land, unpaved roads and gullies) during the rainy season and spring thawing period. Sediment sources from 17 rainfall erosion and seven snowmelt erosion events of varying magnitudes were compared. The Collins and Bayesian mixing models, coupled with geochemical tracers (Cs, V, Cd, Pb and Ag), were applied to assess the contribution proportion of individual sediment sources to suspended sediment. According to the results obtained from the Bayesian mixing model with higher accuracy, cultivated land, unpaved roads and gullies contributed 60.3% (load‐weighted mean contribution [LMC] = 82.8%), 11.0% (LMC = 6.5%) and 28.7% (LMC = 10.7%) of the sediment in the rainy season, respectively. Cultivated land was the dominant sediment source for rainfall erosion, with high rainfall erosivity and sediment concentration. However, for snowmelt erosion, gullies were the primary sediment source (LMC = 66.2%), followed by cultivated land (LMC = 19.8%) and unpaved roads (load‐weighted = 14.0%). Meanwhile, in the spring thawing period, the contributions of unpaved roads to sediment were higher than in the rainy season. During the rainy season, the greatest contributions of TN, TP, TK and SOM were observed from cultivated land, with respective LMC values of 94.2%, 89.4%, 81.1% and 94.8%. With the increase of sediment contribution from gullies in the spring thawing period, its LMC of TN, TP, TK and SOM increased to 42.6%, 58.3%, 65.0% and 38.0%, respectively. The results of the study could be useful for understanding the processes of soil erosion, clarifying the driving mechanism of compound erosion, developing the compound erosion prediction model and optimizing the spatial configuration of erosion control measures.

Effects of Chemicals in Reporter Gene Bioassays with Different Metabolic Activities Compared to Baseline Toxicity.

High-throughput cell-based bioassays are used for chemical screening and risk assessment. Chemical transformation processes caused by abiotic degradation or metabolization can reduce the chemical concentration or, in some cases, lead to the formation of more toxic transformation products. Unaccounted loss processes may falsify the bioassay results. Capturing the formation and effects of transformation products is important for relating the in vitro effects to in vivo. Reporter gene cell lines are believed to have low metabolic activity, but inducibility of cytochrome P450 (CYP) enzymes has been reported. Baseline toxicity is the minimal toxicity a chemical can have and is caused by the incorporation of the chemical into cell membranes. In the present study, we improved an existing baseline toxicity model based on a newly defined critical membrane burden derived from freely dissolved effect concentrations, which are directly related to the membrane concentration. Experimental effect concentrations of 94 chemicals in three bioassays (AREc32, ARE-bla and GR-bla) were compared with baseline toxicity by calculating the toxic ratio (TR). CYP activities of all cell lines were determined by using fluorescence-based assays. Only ARE-bla showed a low basal CYP activity and inducibility and AREc32 showed a low inducibility. Overall cytotoxicity was similar in all three assays despite the different metabolic activities indicating that chemical metabolism is not relevant for the cytotoxicity of the tested chemicals in these assays. Up to 28 chemicals showed specific cytotoxicity with TR > 10 in the bioassays, but baseline toxicity could explain the effects of the majority of the remaining chemicals. Seven chemicals showed TR < 0.1 indicating inaccurate physicochemical properties or experimental artifacts like chemical precipitation, volatilization, degradation, or other loss processes during the in vitro bioassay. The new baseline model can be used not only to identify specific cytotoxicity mechanisms but also to identify potential problems in the experimental performance or evaluation of the bioassay and thus improve the quality of the bioassay data.

Multistep kinetics in self-induced sol–gel process of amorphous anhydride formation during thermal dehydration of potassium tetraborate tetrahydrate

AbstractThe physico-geometrical mechanism and kinetics of the multistep thermal dehydration of potassium tetraborate tetrahydrate was investigated as a model reaction to produce amorphous anhydrate via the self-induced sol–gel process. The thermal dehydration is composed of three consecutive dehydration steps: (1) a surface reaction in the solid-state accompanied by crack formation; (2) a rapid mass loss process accompanied by liquefaction to form the aggregate of the gel powders; and (3) the dehydration of gel powder aggregate to form a glassy anhydride. The changes in the contribution of the individual dehydration steps to the overall process according to the sample particle size and the heating rate (β) were identified as specific features of the multistep dehydration, which was characterized quantitatively using mathematical deconvolution analysis with log-normal four-parameter functions. The difficulty in determining the apparent activation energy (Ea) of the individual dehydration steps using isoconversional analysis due to the changes in the contribution depending on β values was addressed using modulated temperature thermogravimetry. Using the contributions and the apparent Ea of the individual dehydration steps as initial values, the kinetic description of the multistep thermal dehydration was refined through a kinetic deconvolution analysis using the cumulative kinetic equation. As a result, the individual dehydration steps were kinetically characterized as: (1) a surface reaction described by the first-order rate law with Ea,1 of approximately 68 kJ mol−1; (2) a reaction accompanied by liquefaction controlled by an autocatalytic rate behavior with Ea,2 of approximately 123 kJ mol−1; (3) a diffusion-controlled dehydration of gel powder with Ea,3 of approximately 82 kJ mol−1.

Improved simulations of biomass burning aerosol optical properties and lifetimes in the NASA GEOS Model during the ORACLES-I campaign

Abstract. In order to improve aerosol representation in the NASA Goddard Earth Observing System (GEOS) model, we evaluated simulations of the transport and properties of aerosols from southern African biomass burning sources that were observed during the first deployment of the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) field campaign in September 2016. An example case study of 24 September was analyzed in detail, during which aircraft-based in situ and remote sensing observations showed the presence of a multi-layered smoke plume structure with significant vertical variation in single scattering albedo (SSA). Our baseline GEOS simulations were not able to represent the observed SSA variation or the observed organic aerosol-to-black-carbon ratio (OA : BC). Analyzing the simulated smoke age suggests that the higher-altitude, less absorbing smoke plume was younger (∼4 d), while the lower-altitude and more absorbing smoke plume was older (∼7 d). We hypothesize a chemical or microphysical loss process exists to explain the change in aerosol absorption as the smoke plume ages, and we apply a simple loss rate to the model hydrophilic biomass burning OA to simulate this process. We also utilized the ORACLES airborne observations to better constrain the simulation of aerosol optical properties, adjusting the assumed particle size, hygroscopic growth, and absorption. Our final GEOS model simulation with additional OA loss and updated optics showed better performance in simulating aerosol optical depth (AOD) and SSA compared to independent ground- and space-based retrievals for the entire month of September 2016, including the Ozone Monitoring Instrument (OMI) Aerosol Index. In terms of radiative implications of our model adjustments, the final GEOS simulation suggested a decreased atmospheric warming of about 10 % (∼2 W m−2) over the southeastern Atlantic region and above the stratocumulus cloud decks compared to the model baseline simulations. These results improve the representation of the smoke age, transport, and optical properties in Earth system models.

Analysis and design of fast flow liquid Li divertor for fusion nuclear science facility (FNSF) using coupled plasma boundary and LM MHD/heat transfer codes *

The SOLPS-ITER code is utilized to analyze the boundary plasma associated with a fast-flow lithium (Li) divertor configuration in the fusion nuclear science facility (FNSF) tokamak and identify operational regimes with acceptable divertor and core conditions. Plasma transport from the SOLPS-ITER code has been coupled with a liquid metal (LM) MHD/heat transfer code to model a Li open-surface divertor design and assess its impact on the scrape-off-layer (SOL) and core plasma performance. Simulations with only Neon (Ne) impurity seeding have been conducted to evaluate its impact on meeting FNSF design demands for the divertor and upstream plasma parameters. Simulation results indicate that Ne seeding significantly mitigates divertor heat flux but potentially reduces both upstream electron and main ion density due to fuel dilution. The combined application of Ne seeding and deuterium (D2) puffing is required to satisfy the FNSF design requirements on upstream density ( ne,sepOMP ∼1× 1020 m−3) and divertor energy flux ( q⊥,maxOdiv < 10 MW m−2). D2 puffing plays a role in counteracting upstream density drops and augmenting energy and momentum losses through atomic and molecular processes.The inlet Li flow velocity is systematically varied across a wide range to identify acceptable flows and corresponding LM surface temperatures. This comprehensive analysis identifies the acceptable Li flow parameters, LM surface temperature, and emitted Li fluxes necessary to meet the major design constraints. The emitted Li fluxes exhibit minimal impact on the main plasma at surface temperatures up to approximately ∼525 ∘C, corresponding emitted Li fluxes of up to φ Li ∼2 ×1023 atoms s−1. Uncertainties in the Li emission processes from the surface are also investigated, primarily influencing Li loss in the lower surface temperature range ( <525∘ C), with simulation results indicating a minor impact on the divertor and upstream plasma. Conversely, evaporation predominantly drives the Li loss processes at higher surface temperature ranges ( >525∘ C), contaminating both the divertor and upstream plasma.

Relative Contribution of Fungal Communities to Carbon Loss and Humification Process in Algal Sludge Aerobic Composting

Harmful algal blooms in eutrophic lakes pose significant challenges to the aquatic environment. Aerobic composting is an effectively method for processing and reusing dewatered algal sludge. The fungal communities are the main driver of composting. However, their relationship with carbon loss and the humification process during algal sludge composting remains unclear. In this study, the succession of fungal communities in algal sludge composting was investigated via internal transcribed spacer (ITS) rRNA amplicon sequencing analysis. Overall, no significant differences were observed with the α-diversity of fungal communities at different stages. The composition of the fungal communities changed significantly before and after compost maturation and became more stable after the compost maturation. Redundancy analysis showed that the fungal communities were significantly correlated with physicochemical properties, including humic acid (HA)/fulvic acid (FA), temperature, pH, humic acid, microcystins, and CO2. The co-occurrence network showed that different fungal community modules had different relationships with physicochemical properties. Structural equation modeling further revealed that different metabolic or transformation processes may be mainly driven by different fungi modules. The microcystin degradation, carbon loss, and humification during composting were mainly mediated by fungal communities which were mainly influenced by temperature. Humification was influenced not only by fungal communities but also by the microcystin levels. These results show that changes in the fungal community composition and interaction and their relationship with physicochemical properties could represent a useful guide for optimizing the composting process.

How Broncho-Esophageal Cancer Patients Face the Process of Loss and Reconstruction

How Broncho-Esophageal Cancer Patients Face the Process of Loss and Reconstruction

Gradualness of Grammaticalization and Abrupt Change Reconciled: Evidence from Microvariation in Romance

Grammaticalization has long been understood as a process that takes place gradually, but within it, discrete and abrupt changes take place. This tension has been reconciled by claiming that the semblance of a gradual process is given by different parts of a construction undergoing changes at different points in time. Focusing on synchronic microvariation as gradience, this article discusses cases of clitic loss in four Romance varieties (Brazilian Portuguese, Raeto-Romance, some northeastern Italo-Romance varieties, and French), and identifies common patterns in the cells of the paradigms that are most vulnerable to the process of loss. Relating the grammatical and semantic properties of these cells to established typological hierarchies, the paper explores how general cognitive principles can account for the key properties of gradualness and gradience and, ultimately, language change.

A single-cell atlas of lung homeostasis reveals dynamic changes during development and aging

Aging is a global challenge, marked in the lungs by function decline and structural disorders, which affects the health of the elderly population. To explore anti-aging strategies, we develop a dynamic atlas covering 45 cell types in human lungs, spanning from embryonic development to aging. We aim to apply the discoveries of lung’s development to address aging-related issues. We observe that both epithelial and immune cells undergo a process of acquisition and loss of essential function as they transition from development to aging. During aging, we identify cellular phenotypic alternations that result in reduced pulmonary compliance and compromised immune homeostasis. Furthermore, we find a distinctive expression pattern of the ferritin light chain (FTL) gene, which increases during development but decreases in various types of lung cells during the aging process.

Effects of correlations on triplet loss processes in organic phosphorescent emission layers: Accurate and fast master equation modeling

Effects of correlations on triplet loss processes in organic phosphorescent emission layers: Accurate and fast master equation modeling

A Method for Evaluating Coalbed Methane Reservoir Productivity Considering Drilling Fluid Damage

In the process of coalbed methane development, drilling fluid and fracturing fluid cannot achieve absolute compatibility with formation. The incompatibility between the working fluid and reservoir will lead to the intrusion of working fluid into the reservoir and cause reservoir pollution. This is a very common phenomenon. There is a large amount of pulverized coal in the coal seam, and the intrusion of working liquid will be combined with the pulverized coal to form cement to block the seepage space in the reservoir. Since pressure relief and fracturing fluid backflow will be performed at the first time after fracturing, the intrusion range of the working fluid is small, generally reaching 10 m to 50 m. Compared with a conventional gas reservoir or shale gas reservoir, the working fluid loss during CBM development will seriously affect the subsequent production project and even make the gas well lose production capacity. On the other hand, in order to avoid this phenomenon, measures such as acidification or volumetric fracturing are sometimes used to improve the seepage environment near the well and near the fracture. The purpose of this study is to quantitatively evaluate the impacts of working fluid filtration and reservoir reconstruction on production. In this study, a single well productivity evaluation model and sensitivity analysis method considering drilling fluid filtration loss, fracturing fluid filtration loss, reservoir reconstruction and other processes is proposed. The formation mechanism of fluid loss during drilling and fracturing is described, and the productivity evaluation model considering fluid loss is combined with the Langmuir isothermal adsorption equation, steady-state diffusion law, Darcy’s seepage law and Duhamel convolution formation. Combined with the distribution of actual gas reservoir flow characteristics, the sensitivity of single well productivity to gas reservoir porosity, gas reservoir permeability, coal seam adsorption coefficient, working fluid filtration loss and reservoir reconstruction measures are analyzed. Through the analysis and fitting of the actual production data on site, the relationship curve can better fit the field production data, and the evaluation results are in line with the drilling and fracturing conditions at that time and the subsequent production conditions, with small errors. The obtained method is suitable for predicting the productivity of fractured vertical wells in different working conditions and provides a basis for the development and productivity prediction of CBM reservoirs in China and in international cooperation.