bluuebunny/crossref_metadata_2025 huggingface dataset:
Real options in health insurance decisions: the Portuguese ADSE system
Authors: Fonseca Raquel J. , Cunha Luísa
Published: May 2023

The choice between two different health insurance providers is, more often than not, taken from a static point of view, measuring costs and benefits at a specific point in time, not considering all the relevant changes that may occur in life and in health conditions. Inspired by the new regulations set in place by the exclusive Portuguese civil servant’s insurance scheme designated by ADSE, this study proposes a novel approach based on real options for an individual that needs to choose between a private health insurance and the apparently cheaper option provided by ADSE. Starting from the net present value approach, we subsequently show that, depending on some life changing events that may occur, it would be more beneficial for the individual to either abandon the health system or enter it at a later date. By incorporating the value of these options in the net present value calculation, decisions taken are not only more flexible, but also more realistic.
Drones and International Law
Authors: Mignot-Mahdavi Rebecca
Published: May 2023

Through an analysis of the use of drones, Rebecca Mignot-Mahdavi explores the ways in which, in the context of counterterrorism, war, technology and the law interact and reshape one another. She demonstrates that drone programs are techno-legal machineries that facilitate and accelerate the emergence of a new kind of warfare. This new model of warfare is individualized and de-materialized in the sense that it focuses on threat anticipation and thus consists in identifying dangerous figures (individualized warfare) rather than responding to acts of hostilities (material warfare). Revolving around threat anticipation, drone wars endure over an extensive timeframe and geographical area, to the extent that the use of drones may even be seen, as appears to be the case for the United States, as part of the normal functioning of the state, with profound consequences for the international legal order.
Plants Leave Chemical Fingerprints on an Ozone-Depleting Gas
Authors: Stanley Sarah
Published: May 2023

A first-of-its-kind study suggests that isotope analysis could be used to pinpoint sources and sinks of atmospheric methyl chloride.
Stable Barium Isotope Fractionation in Pore Waters of Estuarine Sediments
Authors: Cao Zhimian , Rao Xinting , Li Yating , Hong Qingquan , Wei Lin , Yu Yang , Ehlert Claudia , Liu Bo , Siebert Christopher , Hathorne Ed C. , Zhang Zhouling , Scholz Florian , Kasten Sabine , Frank Martin
Published: May 2023

The development of stable barium (Ba) isotope measurements provides a novel tool to investigate the geochemical cycling of Ba in the ocean and its sediments. In sediment pore waters, gradients of dissolved Ba concentrations result from various diagenetic processes. The distribution and fractionation of Ba isotopes in the pore waters are expected to further improve our understanding of these early diagenetic control mechanisms. Here, we present pore water profiles of dissolved stable Ba isotopic signatures (δ138Bapw) from shallow water sediments covering the entire Pearl River Estuary (PRE) in Southern China. We find pronounced depth‐dependent Ba isotope variations generally showing a shift from heavy to light δ138Bapw signatures from the sediment surface down to 15 cm depth. These gradients are well reproduced by a diffusion‐reaction model, which generates an apparent fractionation factor (138ε) of −0.60 ± 0.10‰ pointing to preferential removal of low‐mass Ba isotopes from the pore water during solution‐solid phase interactions. Consequently, the combined diagenetic processes induce the highest δ138Bapw values of +0.5 to +0.7‰ in the pore waters of the topmost sediment layer. Although the detrital fraction dominates the Ba content in the PRE surface sediments, the determined gradients of pore water Ba isotopes, together with concentration variations of Ba and other redox‐sensitive elements such as manganese (Mn), show that non‐detrital excess Ba carriers including Mn oxides and authigenic barite clearly affect the post‐depositional Ba dynamics. Stable Ba isotopes are thus a potentially powerful tracer of Ba geochemistry during early sediment diagenesis in estuarine depositional environments.
C-reactive protein/albumin ratio is the most significant inflammatory marker in unresectable pancreatic cancer treated with FOLFIRINOX or gemcitabine plus nab-paclitaxel
Authors: Shirakawa Tsuyoshi , Makiyama Akitaka , Shimokawa Mototsugu , Otsuka Taiga , Shinohara Yudai , Koga Futa , Ueda Yujiro , Nakazawa Junichi , Otsu Satoshi , Komori Azusa , Arima Shiho , Fukahori Masaru , Taguchi Hiroki , Honda Takuya , Shibuki Taro , Nio Kenta , Ide Yasushi , Ureshino Norio , Mizuta Toshihiko , Mitsugi Kenji , Akashi Koichi , Baba Eishi
Published: May 2023

There are limited absolute biomarkers for determining the prognosis before first- and second-line palliative chemotherapy in unresectable pancreatic cancer (urPC) patients. To find the best prognostic inflammatory marker, we investigated relationships between overall survival (OS) and six inflammatory markers; C-reactive protein/albumin ratio (CAR), neutrophil–lymphocyte ratio (NLR), prognostic nutrition index (PNI), platelet–lymphocyte ratio (PLR), Glasgow prognostic score (GPS), and prognostic index (PI). We examined 255 patients who received gemcitabine + nab-paclitaxel or FOLFIRINOX as first-line chemotherapy and 159 patients who subsequently underwent second-line chemotherapy. First-line patients with lower CAR had better OS compared to those with a higher CAR (hazard ratio 0.57; 95% confidential index 0.42–77; P < 0.01). Similarly, lower NLR (P = 0.01), higher PNI (P = 0.04), lower PLR (P = 0.03), GPS score of 0 (P < 0.01) and PI score of 0 (P < 0.01) were all associated with better OS. CAR demonstrated the best superiority for determining survival prognosis through the use of area under the curve of time-dependent receiver-operating characteristic curves. Furthermore, a lower CAR before second-line therapy exhibited better OS versus higher CAR (P < 0.01). Therefore, CAR might be a useful biomarker for predicting urPC patient prognosis in both first- and second-line chemotherapy.
Exploratory preferences explain the human fascination for imaginary worlds in fictional stories
Authors: Dubourg Edgar , Thouzeau Valentin , de Dampierre Charles , Mogoutov Andrei , Baumard Nicolas
Published: May 2023

Imaginary worlds are present and often central in many of the most culturally successful modern narrative fictions, be it in novels (e.g.,Harry Potter), movies (e.g.,Star Wars), video games (e.g.,The Legend of Zelda), graphic novels (e.g.,One Piece) and TV series (e.g.,Game of Thrones). We propose that imaginary worlds are popular because they activate exploratory preferences that evolved to help us navigate the real world and find new fitness-relevant information. Therefore, we hypothesize that the attraction to imaginary worlds is intrinsically linked to the desire to explore novel environments and that both are influenced by the same underlying factors. Notably, the inter-individual and cross-cultural variability of the preference for imaginary worlds should follow the inter-individual and cross-cultural variability of exploratory preferences (with the personality trait Openness-to-experience, age, sex, and ecological conditions). We test these predictions with both experimental and computational methods. For experimental tests, we run a pre-registered online experiment about movie preferences (N = 230). For computational tests, we leverage two large cultural datasets, namely the Internet Movie Database (N = 9424 movies) and the Movie Personality Dataset (N = 3.5 million participants), and use machine-learning algorithms (i.e., random forest and topic modeling). In all, consistent with how the human preference for spatial exploration adaptively varies, we provide empirical evidence that imaginary worlds appeal more to more explorative people, people higher in Openness-to-experience, younger individuals, males, and individuals living in more affluent environments. We discuss the implications of these findings for our understanding of the cultural evolution of narrative fiction and, more broadly, the evolution of human exploratory preferences.
Molecule generation using transformers and policy gradient reinforcement learning
Authors: Mazuz Eyal , Shtar Guy , Shapira Bracha , Rokach Lior
Published: May 2023

Generating novel valid molecules is often a difficult task, because the vast chemical space relies on the intuition of experienced chemists. In recent years, deep learning models have helped accelerate this process. These advanced models can also help identify suitable molecules for disease treatment. In this paper, we propose Taiga, a transformer-based architecture for the generation of molecules with desired properties. Using a two-stage approach, we first treat the problem as a language modeling task of predicting the next token, using SMILES strings. Then, we use reinforcement learning to optimize molecular properties such as QED. This approach allows our model to learn the underlying rules of chemistry and more easily optimize for molecules with desired properties. Our evaluation of Taiga, which was performed with multiple datasets and tasks, shows that Taiga is comparable to, or even outperforms, state-of-the-art baselines for molecule optimization, with improvements in the QED ranging from 2 to over 20 percent. The improvement was demonstrated both on datasets containing lead molecules and random molecules. We also show that with its two stages, Taiga is capable of generating molecules with higher biological property scores than the same model without reinforcement learning.
Hypoxia-induced reprogramming of glucose-dependent metabolic pathways maintains the stemness of human bone marrow-derived endothelial progenitor cells
Authors: Lin Dongni , Yan Kaihao , Chen Lingyun , Chen Junxiong , Xu Jianing , Xie Zijing , Li Zhujun , Lin Shuo , Li Jinghuan , Chen Zhenzhou
Published: May 2023

The benefits of hypoxia for maintaining the stemness of cultured human bone marrow-derived endothelial progenitor cells (BM EPCs) have previously been demonstrated but the mechanisms responsible remain unclear. Growing evidences suggest that cellular metabolism plays an important role in regulating stem cell fate and self-renewal. Here we aimed to detect the changes of glucose metabolism and to explore its role on maintaining the stemness of BM EPCs under hypoxia. We identified the metabolic status of BM EPCs by using extracellular flux analysis, LC–MS/MS, and 13C tracing HPLC-QE-MS, and found that hypoxia induced glucose metabolic reprogramming, which manifested as increased glycolysis and pentose phosphate pathway (PPP), decreased tricarboxylic acid (TCA) and mitochondrial respiration. We further pharmacologically altered the metabolic status of cells by employing various of inhibitors of key enzymes of glycolysis, PPP, TCA cycle and mitochondria electron transport chain (ETC). We found that inhibiting glycolysis or PPP impaired cell proliferation either under normoxia or hypoxia. On the contrary, inhibiting pyruvate oxidation, TCA or ETC promoted cell proliferation under normoxia mimicking hypoxic conditions. Moreover, promoting pyruvate oxidation reverses the maintenance effect of hypoxia on cell stemness. Taken together, our data suggest that hypoxia induced glucose metabolic reprogramming maintains the stemness of BM EPCs, and artificial manipulation of cell metabolism can be an effective way for regulating the stemness of BM EPCs, thereby improving the efficiency of cell expansion in vitro.
Prediction of electrostatic properties of reservoir rock in low salinity water injection into carbonate reservoirs
Authors: Parvazdavani Mohammad , Khorsand Movaghar Mohammad Reza
Published: May 2023

Geochemical modeling along with chemical reactions is one of the challenges in modeling of low salinity water injection. The most important issue in the geochemical model is to determine the correct electrical charge distribution model and its tuning parameters. The composition of the rock as well as the candidate water used is effective in determining the type of model and its parameters, so that the tuning parameters are determined based on the history of zeta potential experiments. In this study, in order to determine the correct model of electrical charge distribution and its tuning parameters in carbonate rock samples, first, equilibrium samples of Candidate water with crushed rock are subjected to static zeta potential tests. Then, the diffuse electrical double layer model is used to determine the electrical charge of the rock/water and water/oil surfaces and to predict the zeta potential. In the following, by adjusting the tuning parameters of the model to match the prediction results of the model with the history of the laboratory data, the density of the carbonate rock surface, the equilibrium constants and the kinetics of the governing reactions are determined. The obtained results show that the range of error in zeta potential prediction by the model compared to the laboratory data is from 2 to 20%, which is within the acceptable range of the performance of electrical charge distribution models. Moreover, it could be observed that the error of prediction using DLM model is significantly less than the conventional models (CD-MUSIC and BSM) for different candidate water. Finally, the effect of calculated zeta potential changes is used to calculate the contact angle changes of low salinity water injection based on the coupling of DLVO theory and geochemical model. The results of the study prove that the prediction error is less than 5% compared to the results of the static wettability tests. Based on this, according to the good match between the model and the laboratory results, it is possible to determine the properties of surface sites in surface complexation models of carbonate samples using the proposed approach and the subsequent tuning data of the geochemical model.
Modeling the CO2 separation capability of poly(4-methyl-1-pentane) membrane modified with different nanoparticles by artificial neural networks
Authors: Abdollahi Seyyed Amirreza , Ranjbar Seyyed Faramarz
Published: May 2023

Membranes are a potential technology to reduce energy consumption as well as environmental challenges considering the separation processes. A new class of this technology, namely mixed matrix membrane (MMM) can be fabricated by dispersing solid substances in a polymeric medium. In this way, the poly(4-methyl-1-pentene)-based MMMs have attracted great attention to capturing carbon dioxide (CO2), which is an environmental pollutant with a greenhouse effect. The CO2 permeability in different MMMs constituted of poly(4-methyl-1-pentene) (PMP) and nanoparticles was comprehensively analyzed from the experimental point of view. In addition, a straightforward mathematical model is necessary to compute the CO2 permeability before constructing the related PMP-based separation process. Hence, the current study employs multilayer perceptron artificial neural networks (MLP-ANN) to relate the CO2 permeability in PMP/nanoparticle MMMs to the membrane composition (additive type and dose) and pressure. Accordingly, the effect of these independent variables on CO2 permeability in PMP-based membranes is explored using multiple linear regression analysis. It was figured out that the CO2 permeability has a direct relationship with all independent variables, while the nanoparticle dose is the strongest one. The MLP-ANN structural features have efficiently demonstrated an appealing potential to achieve the highest accurate prediction for CO2 permeability. A two-layer MLP-ANN with the 3-8-1 topology trained by the Bayesian regulation algorithm is identified as the best model for the considered problem. This model simulates 112 experimentally measured CO2 permeability in PMP/ZnO, PMP/Al2O3, PMP/TiO2, and PMP/TiO2-NT with an excellent absolute average relative deviation (AARD) of lower than 5.5%, mean absolute error (MAE) of 6.87 and correlation coefficient (R) of higher than 0.99470. It was found that the mixed matrix membrane constituted of PMP and TiO2-NT (functionalized nanotube with titanium dioxide) is the best medium for CO2 separation.
Mother-to-child transmission of SARS-CoV-2 infection in high-income countries: a systematic review and meta-analysis of prospective observational studies
Authors: Morniroli Daniela , Vizzari Giulia , Tosi Martina , Treglia Giorgio , Corsello Antonio , Marchisio Paola , Mosca Fabio , Agostoni Carlo , Giannì Maria Lorella , Milani Gregorio Paolo , Pugni Lorenza
Published: May 2023

Mother-to-child transmission of SARS-CoV-2 has been reported since the onset of the COVID-19 pandemic. We conducted a study to summarize evidence on the risk of mother-to-child transmission in the first 30 days after birth in high-income countries and to evaluate the association between preventive measures and the risk of infection for the neonate. A systematic review and meta-analysis were undertaken following PRISMA guidelines. The National Library of Medicine, Web of Science, and Excerpta Medica databases were screened on February 26, 2022. All prospective observational studies addressing the frequency of infection in infants born to mothers SARS-CoV-2 positive were included. Twenty-six studies were included, reporting data of 2653 mothers with SARS-CoV-2 and 2677 neonates. The proportion meta-analysis pointed out an overall estimate of SARS-CoV-2 infection among infants of 2.3% (95% CI: 1.4–3.2%). Data from studies with (1.4%, 95% CI: 0.8–2) and without (1.3%, 95% CI: 0.0–2.7%) rooming-in provided similar risk of infection. Adopting at least two prevention measures during rooming-in resulted in a rate of mother-to-child infection of 1.0% (95%CI: 0.3–1.7%). The results of this study show a low rate of perinatal infection, support the rooming-in and confirm the effectiveness of preventive measures in reducing the risk of mother-to-child viral transmission.
Rigorous and rapid evidence assessment in digital health with the evidence DEFINED framework
Authors: Silberman Jordan , Wicks Paul , Patel Smit , Sarlati Siavash , Park Siyeon , Korolev Igor O. , Carl Jenna R. , Owusu Jocelynn T. , Mishra Vimal , Kaur Manpreet , Willey Vincent J. , Sucala Madalina L. , Campellone Tim R. , Geoghegan Cindy , Rodriguez-Chavez Isaac R. , Vandendriessche Benjamin ,   The Evidence DEFINED Workgroup, Park Siyeon , Mishra Vimal , Rodriguez-Chavez Isaac R. , Goldsack Jennifer C.
Published: May 2023

Dozens of frameworks have been proposed to assess evidence for digital health interventions (DHIs), but existing frameworks may not facilitate DHI evidence reviews that meet the needs of stakeholder organizations including payers, health systems, trade organizations, and others. These organizations may benefit from a DHI assessment framework that is both rigorous and rapid. Here we propose a framework to assess Evidence in Digital health for EFfectiveness of INterventions with Evaluative Depth (Evidence DEFINED). Designed for real-world use, the Evidence DEFINED Quick Start Guide may help streamline DHI assessment. A checklist is provided summarizing high-priority evidence considerations in digital health. Evidence-to-recommendation guidelines are proposed, specifying degrees of adoption that may be appropriate for a range of evidence quality levels. Evidence DEFINED differs from prior frameworks in its inclusion of unique elements designed for rigor and speed. Rigor is increased by addressing three gaps in prior frameworks. First, prior frameworks are not adapted adequately to address evidence considerations that are unique to digital health. Second, prior frameworks do not specify evidence quality criteria requiring increased vigilance for DHIs in the current regulatory context. Third, extant frameworks rarely leverage established, robust methodologies that were developed for non-digital interventions. Speed is achieved in the Evidence DEFINED Framework through screening optimization and deprioritization of steps that may have limited value. The primary goals of Evidence DEFINED are to a) facilitate standardized, rapid, rigorous DHI evidence assessment in organizations and b) guide digital health solutions providers who wish to generate evidence that drives DHI adoption.
Illuminance-tuned collective motion in fish
Authors: Lafoux Baptiste , Moscatelli Jeanne , Godoy-Diana Ramiro , Thiria Benjamin
Published: May 2023

We experimentally investigate the role of illumination on the collective dynamics of a large school (ca. 50 individuals) of Hemigrammus rhodostomus. The structure of the group, defined using two order parameters, is quantified while progressively altering the visual range of the fish through controlled cycles of ambient light intensity. We show that, at low light levels, the individuals within the group are unable to form a cohesive group, while at higher illuminance the degree of alignment of the school correlates with the light intensity. When increasing the illuminance, the school structure is successively characterized by a polarized state followed by a highly regular and stable rotational configuration (milling). Our study shows that vision is necessary to achieve cohesive collective motion for free swimming fish schools, while the short-range lateral line sensing is insufficient in this situation. The present experiment therefore provides new insights into the interaction mechanisms that govern the emergence and intensity of collective motion in biological systems.
Correction: Effectiveness of a novel gene nanotherapy based on putrescine for cancer treatment
Authors: Lores Saínza , Gámez-Chiachio Manuel , Cascallar María , Ramos-Nebot Carmen , Hurtado Pablo , Alijas Sandra , López López Rafael , Piñeiro Roberto , Moreno-Bueno Gema , de la Fuente María
Published: May 2023

Correction for ‘Effectiveness of a novel gene nanotherapy based on putrescine for cancer treatment’ by Saínza Lores et al., Biomater. Sci., 2023, https://doi.org/10.1039/d2bm01456d.
A Cu-promoted reaction of β-keto trifluoromethyl amines enabling stereoselective synthesis of trifluoromethylated aziridines
Authors: Wang Nana , Du Youlong , Mei Haibo , Escorihuela Jorge , Han Jianlin
Published: May 2023

A Cu-promoted intramolecular cyclization of β-keto trifluoromethyl amines is developed, which provides the unprotected trifluoromethylated aziridines with good yields and excellent stereoselectivity.
Recent progress in porous catalysts for dehydrogenation of ammonia borane
Authors: Liu Dan , Zhou Cheng , Yang Zhimao , Wang Ge , Kong Chuncai , Liu Ben
Published: May 2023

The recent progress in porous materials applied as catalysts in AB solvolysis is investigated in this review. The major challenges and the future development directions for advanced porous catalysts for efficient AB solvolysis are put forward.
Chalcogen composition driven enhancement of catalytic efficiency in zirconium based monolayers: insight from reaction coordinate mapping
Authors: Tomar Shalini , Chakraborty Sudip
Published: May 2023

Exploring the bifunctional catalytic activity of zirconium dichalcogenides monolayers for hydrogen production through water splitting process.
Altruistic cooperative adaptive cruise control of mixed traffic platoon based on deep reinforcement learning
Authors: Lu Sikai , Cai Yingfeng , Chen Long , Wang Hai , Sun Xiaoqiang , Gao Hongbo
Published: May 2023

Cooperative adaptive cruise control (CACC) realizes efficient, intelligent control of vehicle acceleration, deceleration, and steering, through inter‐vehicle communication and cooperative control. However, the close combination of the platoon makes it difficult for other vehicles to cut‐in, which can lead to severe traffic jams on certain sections of the road. The control effect of the CACC depends on the platoon penetration rate, which is the percentage of connected and autonomous vehicles (CAVs) in the total number of platoon members. There is no quantitative control method for different penetration rates, and it is difficult to quantify the impact of CACC vehicles on traffic. Therefore, this paper proposes an innovative CACC control method based on deep reinforcement learning (DRL). First, the altruism control and the quantitative control of the car‐following strategy are realized by the virtual car‐following distance method to reduce the exclusivity of the CACC platoon or improve the road utilization efficiency. Second, a more appropriate platoon reward function and collision avoidance method are proposed. Finally, the Car Learning to Act (CARLA) simulator is used. The obtained results confirm that the CACC control of CAVs based on DRL can absorb speed oscillation and improve fuel economy.
A comparative analysis of type Ia supernovae 2018xx and 2019gbx
Authors: Li Yangyang , Zheng Sheng , Zeng Xiangyun , Wang Xiaofeng , Burke Jamison , Pellegrino Craig , Esamdin Ali , Lin Xinkui , Wang Yong , Iskandar Abdusamatjan , Zhang Jujia , Wei Peng , Bird Sarah A. , Zeng Shuguang , Huang Yao , Andrew Howell D. , Azaleee Bostroem K. , McCully Curtis , Hiramatsu Daichi , Hosseinzadeh Griffin , Li Wenxiong , Zhang Tianmeng , Wang Lifan , Zhou Guangrong
Published: May 2023

We present a comparative study of two nearby type Ia supernovae (SNe Ia), 2018xx and 2019gbx, that exploded in NGC 4767 and MCG-02-33-017 at a distance of 48 Mpc and 60 Mpc, respectively. The B-band light curve decline rate for SN 2018xx is estimated to be 1.48 ± 0.07 mag and for SN 2019gbx it is 1.37 ± 0.07 mag. Despite the similarities in photometric evolution, quasi-bolometric luminosity, and spectroscopy between these two SNe Ia, SN 2018xx has been found to be fainter by about ∼0.38 mag in the B-band and has a lower 56Ni yield. Their host galaxies have similar metallicities at the SN location, indicating that the differences between these two SNe Ia may be associated with the higher progenitor metallicity of SN 2018xx. Further inspection of the near-maximum-light spectra has revealed that SN 2018xx has relatively strong absorption features near 4300 Å relative to SN 2019gbx. The application of the code TARDIS fitting to the above features indicates that the absorption features near 4300 Å appear to be related to not only Fe II/Mg II abundance but possibly to the other element abundances as well. Moreover, SN 2018xx shows a weaker carbon absorption at earlier times, which is also consistent with higher ejecta metallicity.
Influence of the grinding wheel recipe on the cutting force components during grinding
Authors: Romanenko A.M. , Shatko D.B. , Bakanov A.A. , Strelnikov P.A.
Published: May 2023

The issues of the components of a grinding wheel recipe, namely, abrasive grains, bonds and various fillers on the cutting forces during grinding are considered in the article. The following types of fillers were studied: fused alumina microspheres, which are a non-burning hollow filler, glass microspheres used as a hollow melting filler, and a burning filler in the form of crushed fruit pits. On the basis of the obtained experimental data, generalized statistical models of the dependence of the magnitude of cutting forces during grinding on the percentage of grains, bond and fillers were developed. From the analysis of the pair correlation coefficients of the models of the grinding force components, it was concluded that the percentage of grains, bond, glass microspheres have the strongest effect on the cutting force sand the effect of fused alumina microspheres and fruit pits is negligible. Based on the results obtained, conclusions are formulated in the form of practical recommendations for reducing cutting forces.
Improvement of the well cementing technology, increasing the reliability of the annule isolation and preserving the permeability of the reservoir
Authors: Hadid Mahmoud , Minchenko Yulia , Shemelina Olga , Ovchinnikov Vasily , Pavelyeva Yulia
Published: May 2023

The article presents measures to improve the quality of cementing the production string of high-performance wells. The relevance of the proposed technological solutions is substantiated. The results of experimental studies of the installation simulating the processes occurring during the thickening of the cement slurry under the action of gravitational forces are presented. An algorithm for creating overpressure on the wellhead during fastening of the production string is proposed. The compositions of process fluids are described, which increase the reliability of the annular space isolation and preserve the permeability of the reservoir, and provide the main data on the results of their laboratory studies. For cementing the annular space of the production string, the composition of the expanding cement slurry has been developed and the procedure for its preparation has been established. The proposed solution has low water separation and high sedimentation resistance; has adjustable rheological parameters. Cement stone is characterized by low gas permeability and high strength properties.
Rectangular plate calculation algorithm for static loads with geometric nonlinearity
Authors: Balamirzoev Abdul , Ahmedova (Sephikhanova) Saida , Kurbanova Elina , Isaeva Amina
Published: May 2023

The aim of this study is to develop an algorithm for calculating rectangular plates for statistical loads taking into account geometrical nonlinearity on the basis of difference equations of the method of sequential approximations taking into account full and partial contact with elastic base. For our study, we used methods: finite elements method and method of sequential approximations, and theory of plate calculation considering large deflections. Results: a method, algorithm, and calculation algorithm for rectangular plates in the geometrically nonlinear formulation using difference equations of the method of sequential approximations (SEA) taking into account full and partial contact with the elastic base have been developed. Conclusion: An algorithm has been developed for the computation of rectangular plates in geometrically nonlinear formulation using difference equations of the method of sequential approximations. It is recommended to use generalized difference equations of finite difference method when calculating rectangular plates for the action of piecewise distributed transverse loads without taking into consideration interaction with elastic base. Having more compact form of recording, the solution obtained by using them has comparable accuracy as the version using SEA difference equations.
Mathematical modeling of milling cutters with variable radius for processing holes with an equiaxed contour
Authors: Malneva Julia , Kuts Vadim , Mitrofanov Maxim , Beye Abdrahamane
Published: May 2023

The aim of the study is to model the cutting edges, front and rear surfaces, the pitch of the teeth and the cutting surface of a milling cutter with a variable radius for processing holes with an equiaxed contour. In the process of modeling, the method of compiling mathematical models of technological processes for obtaining surfaces of parts by cutting was used. As a result, the equations of the cutting edges of the milling cutter, the equations of the producing surface were obtained, parametric equations of the rear and front surfaces of the cutting teeth were constructed, and conclusions were drawn.
Method for clarifying the boundaries of inhomogeneity on a dynamic image for EIT
Authors: Aleksanyan Grayr , Gorbatenko Nikolay , Konko Maria , Nguyen Manh Cuong
Published: May 2023

This article proposes an algorithmic solution to refine the boundaries of heterogeneity in a dynamic image for EIT. The essence of the method is to calculate the rate of change of the color value of each pixel p(i,j) Gn for a given research area. Next, the received data array is processed and the initial image of the heterogeneity region Gn is scaled. Software has been developed that implements the proposed algorithmic solutions. The method of automatic control of the parameters of the EIT examination is implemented, which consists in the automatic mode of operation without operator intervention from the moment of setting the parameters of the examination to the receipt of the final result. The operation of the method for refining the boundaries of inhomogeneity has been tested on computer models. According to the results of the study, the error in determining γ was reduced by 1.44 times. Thus, it seems possible to reduce it when transmitting and digitizing measurement data.
Geometric calculation of non-circular gear segments of the planetary mechanism in rotary hydraulic machines
Authors: Volkov Gleb , Fadyushin Denis , Vedernikov Maksim
Published: May 2023

The article discusses the improvement of the methods of geometric design of positive-displacement hydraulic machines with floating satellites. At the first stage, based on standard methods, an “average” round-link planetary mechanism, having the number of teeth as in the designed hydraulic machine, is calculated. At the second stage, the same-type cyclic functions characterizing the paths of the center of the satellite in the coordinates associated with each of the central gearwheels are specified. At the third stage, the coordinate arrays of the satellite in a variety of its positions are calculated. The angular position of the satellite relative to one of the profiled gearwheels (for example, the sun gearwheel) provides equidistance of the centroid of this gearwheel to the path of the center of the satellite. The angular position of the satellite relative to the other profiled wheel is determined by its running around the first wheel. At the final stage of the design, the satellite is constructed in a variety of positions, and the profile of the corresponding non-circular gear rim is obtained as an envelope of the family of satellite curves-profiles.
Study of chemical properties combination chemical method of wastewater treatment by methods IR-spectroscopy and X-ray diffraction
Authors: Amonov M.R. , Niyozov E.D. , Amonova M.M. , Nazarov S.I. , Ganiev B.S.
Published: May 2023

Complex formation processes of sericin compounds with Ni2+, Cu2+, Zn2+, Co2+ salts were studied. The possibility of maximum extraction of sericin was determined when wastewater is purified by the proposed method, and the developed purification method is recommended for amino acid purification of wastewater. By using the coagulants Al2(SO4)3•18H2O and FeCl3•6H2O and flocculant PAA together with the proposed sorbent, the concentration of coagulants in wastewater is 0.75 mg/l, 0.5 mg/l, 0.5 mg/l, and the amount of kaolin bentonite, respectively. An acceptable content of 2.0 g/l has been suggested. When the composition of the dry residue obtained after treatment with a composition consisting of bentonite, kaolin and aluminum sulfate was analyzed using X-ray structural analysis, it was found that the residue contained crystal spheres. The obtained results proved that the diffract grams of dry residue and bentonite samples are almost identical. It was found out in the research that these crystal spheres belong to the mineral contained in bentonite.
Investigation of thermal properties and composition on basalts of the Aydarkul deposit by methods DTA/DTG and X-ray diffraction
Authors: Nazarov Sayfulla , Razzokov Khasan , Shirinov Gayrat , Niyozov Erkin , Rashidova Rano , Rasulov Mirzo , Ganiev Bakhtiyor
Published: May 2023

To study the applicability of the basalt fiber through various experimental works in thermal and chemical environments, lining heat-insulating materials basis on basalt of Aydarkul deposit were compared and discussed. The identification and study phase pert structures lining heat-insulating materials basis on basalt of Aydarkul deposit used X-ray diffraction analysis. The basalt fiber showed better strength retention than the glass fiber at relatively high temperature. The article studies the endothermic effects of the thermolysis process, which appear at a temperature of 80 ÷240 0C. They show the decomposition of clay impurities or the removal of hygroscopic water contained in rocks. The chemical and mineralogical composition of the basalts of the Aydarkul deposit has been studied by such modern methods as X-ray diffraction and differential thermal analysis methods.
Optical visualization as an effective tool for studying the flow structure in a small-sized centrifugal electric pump
Authors: Bobkov Alexandr , Krivenko Marina
Published: May 2023

The article is devoted to the substantiation of the need for optical visualization of the structure of a 2-dimensional flow in small-sized centrifugal electric pumps of the spacecraft thermal control system. Reducing the size of the interblade channels of the pump impeller makes it impossible to use traditional methods of flow sensing due to disturbances introduced by the probes. Due to the lack of experimental data, in the study of flows in small pumps, a flow model developed for full-size centrifugal pumps is used. The most common of these are the Euler jet model or the two-zone jet-trail model. Studies by numerical methods based on these models cannot be verified for adequacy to real flows due to the lack of experimental data necessary to validate the results obtained. Under such conditions, the study of the flow structure by experimental methods, in particular, using optical visualization by the method of indicator washable coatings in the near-wall layer of the interblade channels of the impeller of pumps, becomes important. This article describes: 1) the technology of imaging; 2) structural elements of the flow, which are identified in the flow patterns in the near-wall layer; 3) results of visualization of the flow in the impellers of centrifugal pumps with a diameter of 41·10-3 m. New data are obtained on the structure of the flow under flow regimes in the non-self-similar zone of the Reynolds number in relative motion.
Possibilities of using alizarin and neutral red indicators to determine the neutralized layer of concrete in the field
Authors: Loginova Svetlana , Razgovorov Pavel , Goglev Ilya
Published: May 2023

The article concerns with the prospects of using the phenolphthalein test solution in the practice of surveying concrete and reinforced concrete building structures in planta. The problem of the study is the limits of application of the phenolphthalein test solution on the pH level of the determined concrete (the indicator works only at 8≤rn≤10). There is a need of expanding the phenolphthalein test solution application. In order to determine the different pH zones of concrete we have to modernize the method by adding other indicators to phenolphthalein. The standard phenolphthalein test solution does not allow a high degree of accuracy in determining the most sensitive to carbonation boundary zones of concrete. We proposed to modernize the phenolphthalein sample solution by using additional acid-base indicators alizarin and neutral red. We presented the results of experiments on measuring the surface neutralized layer of concrete by alcoholic solutions of acid-base indicators alizarin and neutral red on different age and size concrete samples. As a result, one of the proposed indicators (neutral red) allows to expand the phenolphthalein test solution application. We compared the results obtained by the traditional and modified methods. According to it, the proposed modified method is more accurate one.
The use of superplasticizers in multicomponent concrete mixtures
Authors: Stenechkina Kseniya
Published: May 2023

In addition to the positive effect of the introduction of a superplasticizer, there are also negative ones: an increase in the period of structure formation, a significant air entrainment and, as a result, a decrease in strength. One of the ways to reduce the negative impact on the structure and properties of concrete composites is the method of preparing a suspension, which consists in first dissolving 10% of the amount of cement in all the mixing water in a concrete mixer for 1-2 minutes. Then load the rest of the cement and aggregate. Preliminary dissolution in water mixing with superplasticizer leads to the formation of a colloidal solution containing an increased amount of micro- and nanoparticles. When a superplasticizer is introduced into a cement-water suspension, particles with a high degree of dispersion are formed, as well as calcium hydrosilicate cristolites with a size of 1-3 nm. This sharply increases the activity of the superplasticizer and, consequently, improves the mobility of the concrete mixture. For example, from P2 to P3, from P3 to P5. This allows to reduce the consumption of the additive by 1.5 - 2 times. It has been established that the superplasticizer can be adsorbed only on hydrate neoplasms. For pre-treatment, it is necessary to use special equipment with high energy consumption such as RPA, fine grinding mills, disintegrators and various activators. Obtaining a cement-water suspension can be carried out in mortar, concrete mixers, in mixers of any type. The concrete mixture consists of cement, crushed stone, sand, water and superplasticizer C-3, determination of the draft of the cone using the Abrams cone, determination of the cubic strength using a hydraulic press in accordance with GOST 10180-2012. It becomes possible to increase the grade in terms of workability as a result of preliminary hydroactivation of the plasticizing additive, which leads to a decrease in its consumption. This method of hydroactivation of superplasticizers for the manufacture of cement concretes can be used to save the consumption of a plasticizing additive.
Splashing criterion when drop impacting on the liquid with liquid film
Authors: Saushin Ilya
Published: May 2023

The paper considers a new method to combat the secondary drops ejecting into the gaseous medium when a single drop impacts the liquid surface. Possible increase in the critical Weber number when a discrete drop of liquid separates into the gaseous medium due to the stability loss of the Rayleigh jet has been shown experimentally. The degree of increase in the critical Weber number is commensurate with the ratio of the surface tension coefficients of liquids to the gaseous medium and can be estimated from the proposed analytical ratio.
Kinetic laws of dimethyl ether synthesis reaction
Authors: Shukurov Jasur , Fayzullaev Normurot
Published: May 2023

The work consists of a detailed study of the influence of pressure, temperature, volume velocity and the molar ratio of H2/CO on CO conversion and DME output. CO conversion and DME synthesis in the presence of a CuO·ZnO·Al2O3·ZrO2·CaO/bentonite: γ-Al2O3 catalyst was studied in terms of their layer-by-layer loading. It was shown that the method of loading catalysts in the ratio of 2:1:2 is the best option. Further studies of the catalytic activity of the samples were carried out using a 2:1:2 loading method. Operating conditions T=290 °C, P=2 MPa, H2/CO=2.5, volume velocity 1000 h-1, conversion of CO in a single pass through the catalyst bed DME output “Crystal 5000” gas chromatograph, TriStar II (3020) was determined using an automatic gas adsorption analyzer model BJH (Barett-Joyner-Halenda). The phase composition of the catalyst samples was studied by X-ray phase analysis (X-ray diffraction - XRD) using a Shimadzu XRD-6000 diffractometer. The surface morphology of the samples was studied by scanning electron microscope based on VEGA IILMU electron microscope and INCA ENERGY 350 energy dispersive microanalysis.
Parameters and criteria the construction of the Beijing expressway for urban planning
Authors: Xue Tian , Chunlu Gao
Published: May 2023

The purpose of the study is to investigate parameters and criteria the construction of the Beijing expressway for urban planning. The main methods of the study were statistical methods of studying the economic situation, analogy and generalization of the received information. Results. The assessment presented the method and scale of the construction of expressways, the method of construction of auxiliary roads, the method of designing entrance and exit ramps, research on the choice of overpasses for interchanges, as well as the impact of the construction of expressways on the entire urban transport environment. As part of the development of Beijing's transport infrastructure, it is necessary to coordinate the development of Beijing-Tianjin-Hebei transport. It continuing the reasonable construction of expressways. In this article, we presented main measures to improve the ring road that development of transport infrastructure in Beijing, Tianjin and Hebei, and active implementation of information systems in traffic management.
Effect of protecting coatings on mechanical properties of metal surfaces
Authors: Farmakovskaya A.A. , Okorokova N.S. , Perchenok A.V.
Published: May 2023

The effects of epoxy-polyester based powder coatings on the mechanical properties of plates made of rolled steel sheets were investigated in this work. The effect of coatings of the order of 100 µm thickness on the mechanical properties of specimens of 0.7-1.5 mm thick was considered. Tests carried out at room and elevated temperatures showed that thin coatings had an insignificant effect on the mechanical properties of the plates in bend and tensile tests. In particular, the tensile and bending stiffness of the plates is virtually unchanged in the presence of coatings, despite the fact that the modulus of elasticity determined in tests of steel plates with coatings is always somewhat lower than the Young's modulus of steel, due to the increased thickness of specimens determined in the presence of coatings. In compression strength tests, on the contrary, the influence of coatings is significant. In the overcritical mode of deformation, the load carrying capacity of coated plates is significantly reduced and their critical load of stability loss becomes 1.2-2.3 times lower (depending on substrate thickness) compared to uncoated samples. This effect can be explained by the influence of residual temperature stresses that arise in the samples after coating.