bluuebunny/crossref_metadata_2025 huggingface dataset:
Possible transformation of agriculture using artificial intelligence: Business opportunities
Authors: Dakhkilgova Kamila Bagaudinovna , Aygumov Timur Gadzhievich , Mirzoeva Nazifat Mukhtarovna
Published: November 2024

Artificial intelligence is one of the promising technologies of the decade. Its capabilities are exponentially increasing and similarly its applications in different fields and areas. One of its main advantages is that it can automate any sector or industry with reduction of workforce and any unwanted aspects. It also increases the quality and the production, which is valuable in the world of overpopulation. The following article will look into the use of artificial intelligence in the sector of agriculture. The present state of the use of the technology in the agricultural sector will also be covered in details. The future possible application of the technology will be presented at the end of the work.
The influence of environmental factors on the development of the cardiovascular system: Studying the impact of air, water and soil pollution on the formation and functioning of the heart and blood vessels of students
Authors: Magomedova Z.A. , Abumuslimov S.S. , Medoeva A.
Published: November 2024

This study delves into the intricate interplay between environmental factors and the development of the cardiovascular system among students. Environmental pollution, stemming from various sources such as air, water, and soil contamination, poses a significant threat to human health. In particular, the cardiovascular system, responsible for vital functions like blood circulation and oxygen transport, is vulnerable to the adverse effects of environmental pollutants. By meticulously examining the impact of these pollutants on the hearts and blood vessels of students, this research endeavors to unravel the complex mechanisms underlying cardiovascular health in the context of environmental exposure. Through comprehensive analysis and data interpretation, this study aims to shed light on the specific pathways through which environmental factors influence cardiovascular development, thereby providing valuable insights for public health initiatives and policy interventions. Ultimately, the findings of this research have the potential to inform targeted strategies aimed at mitigating environmental pollution and safeguarding the cardiovascular well-being of students and the broader population.
Innovative sustainable production technologies offer energy-efficient solutions for industrial enterprises
Authors: Arsakhanova Zina , Kukoba Pavel , Dzhioeva Oksana
Published: November 2024

Energy efficiency has become a critical focus for industrial enterprises aiming to reduce costs and minimize environmental impact. This paper explores modern technologies in sustainable production that offer energy-efficient solutions for industrial operations. By adopting innovative approaches and leveraging advanced technologies, industrial enterprises can optimize their energy usage, streamline processes, and enhance overall sustainability. Key areas of focus include renewable energy integration, advanced automation and control systems, predictive maintenance, and energy management software. Through case studies and analysis of industry trends, this paper highlights the potential benefits and challenges associated with implementing energy-efficient solutions in industrial settings. Ultimately, the adoption of these technologies presents opportunities for industrial enterprises to achieve greater efficiency, competitiveness, and environmental stewardship in the pursuit of sustainable production.
Biotechnology and the Green Future of Reproductive Health: Innovations for an Environmentally Sustainable Approach
Authors: Sarbasheva Marziyat , Khamchiev Kureysh , Isaeva Petmat
Published: November 2024

In the face of global environmental challenges and the imperative to promote sustainability, the intersection of biotechnology and reproductive health presents an opportunity for innovative solutions. This paper explores the potential of integrating biotechnological advancements into reproductive health practices to foster environmentally sustainable approaches. By examining emerging technologies such as eco-friendly fertility treatments, biodegradable contraceptives, and sustainable reproductive tissue preservation methods, this study highlights how biotechnology can contribute to reducing the environmental footprint of reproductive health interventions. Additionally, it discusses the ethical considerations, regulatory frameworks, and societal implications associated with the adoption of these technologies. Ultimately, this paper envisions a green future for reproductive health, where biotechnology plays a pivotal role in promoting both human well-being and environmental stewardship.
Environmental Factors and Heart Health: Considering Environmental Influences as aspect of sustainable development
Authors: Khamchiev Kureysh , Ibraeva Salima , Zhiengalieva Ardak , Zukhura Sarbasheva
Published: November 2024

Heart health research is increasingly focusing on the effects of the environment on cardiovascular function. This review discusses the role of various environmental factors, such as air quality, noise levels, access to green space, and environmental urban planning strategies, in shaping heart health. Both direct and indirect mechanisms through which the environment may influence the development of cardiovascular disease are discussed, including inflammation, stress, physical activity, and sleep quality. Understanding these relationships is important for the development of effective programs for the prevention and management of cardiovascular diseases, based on consideration and improvement of environmental quality.
Strategies for survival and adaptation of the population in new climatic and environmental conditions in the context of forced migration
Authors: Ttsutsulaeva Sapiyat
Published: November 2024

This research delves into the intricate dynamics of survival and adaptation strategies employed by the Chechen population amidst the backdrop of forced migration to new climatic and ecological settings. Through a comprehensive examination of historical archives and contemporary studies, the study navigates through the nuanced shifts in climate patterns and environmental conditions in regions where Chechens have been resettled, shedding light on the multifaceted impact of these transformations on their daily lives and adaptive mechanisms. Moreover, it scrutinizes the myriad strategies adopted by the Chechen community to navigate and surmount the myriad challenges posed by their altered surroundings. By unraveling the complexities of adaptation in the face of forced migration, this study not only enriches our understanding of the resilience of migrant populations but also offers invaluable insights for the development of robust support frameworks tailored to the unique needs of displaced communities.
Environmental Impact in Reproductive Health Care in sustainable development
Authors: Rakhimzhanova Zhanar , Kuteshat Sultan , Salamanova Khava
Published: November 2024

Reproductive health care plays an important role in sustainable development, but also has significant environmental impacts. This review examines the environmental impact of reproductive health care and explores methods for reducing the environmental footprint of this area. Various aspects are analyzed, including the use of disposable materials, energy costs of procedures, waste emissions, and the use of chemicals and pharmaceuticals. Modern approaches to reducing negative impacts are presented, such as moving towards more efficient use of resources, using biodegradable materials, improving the energy efficiency of clinics and introducing alternative treatments using natural remedies. The work calls for the development and adoption of policies aimed at integrating environmentally sustainable practices into reproductive health care to help achieve sustainable development goals.
Architecture of methodological approaches in the management of receivables and accounts payable of an agricultural organization of the fisheries complex of the region
Authors: Lysenko Yu.V. , Ovsyanitskaya L. Y. , Lysenko M.V. , Filipsonova E. N.
Published: November 2024

The survival and sustained success of any agricultural organization hinges on a fundamental pillar: financial stability. This isn't simply about having enough money to operate; it's about building a resilient system that can weather unpredictable market fluctuations, volatile commodity prices, and unforeseen natural disasters. A financially robust agricultural organization operates with a degree of independence from market whims, decreasing its vulnerability to financial hardship and the ever-present threat of bankruptcy. This research delves into the critical importance of a holistic and scientific approach to analyzing key financial indicators within agricultural organizations. Such an approach goes beyond simply reviewing financial statements; it involves a nuanced understanding of the underlying factors that influence those indicators. For instance, examining the effectiveness of managing receivables and payables offers valuable insights into an organization's cash flow management practices and its ability to meet its financial obligations. To gain tangible insights into the financial health of agricultural organizations, this research utilizes the annual accounting (financial) statements of a fishery complex from 2020- 2022. Analyzing these statements allows for the assessment of key financial ratios, trends in revenue and expenditure, and the overall efficiency of operations. By applying these recommendations, agricultural organizations can strengthen their financial foundations, improve their resilience, and ultimately achieve greater long-term success in the face of an increasingly challenging agricultural landscape.
Localized shear strength mobilization at geosynthetic interfaces caused by spreading soil downslope
Authors: Thiel Richard , Giroud Jean-Pierre
Published: November 2024

Localized interface shear strength failures have occurred below the tracks of a bulldozer during placement and spreading of cover soils on slopes lined with geosynthetics. The mechanisms of these types of failures are rarely considered and evaluated in design reports and calculations. A paper on this subject was recently published by Thiel and Giroud [1], but the analyses presented in that paper were limited to upslope bulldozer pushing. The present paper extends those analyses to consider downslope bulldozer pushing and deceleration forces. The paper presents straightforward equations of equilibrium that the user can easily input into a spreadsheet to model various geometries, bulldozer sizes, and shear strengths, and to determine the acceptable size of the soil pile being pushed for those conditions. The equations provided should be useful for design engineers to avoid localized slippage on slopes where bulldozers are spreading soil materials over geosynthetics, or for forensic experts who evaluate why slippage may have occurred.
ECCD system design activities for JA DEMO
Authors: Oda Yasuhisa , Nagasaki Kazunobu , Fukuyama Atsushi , Maekawa Takashi , Idei Hiroshi , Seino Tomohiro , Yanagihara Kota , Aiba Nobuyuki , Yajima Satoru , Shinya Takahiro , Ikeda Ryosuke , Kajiwara Ken , Kubo Shin , Tobita Kenji , Sugiyama Shota , Uto Hiroyasu , Sakamoto Yoshiteru
Published: November 2024

ECCD system design activities for JA DEMO is in progress. Activities contains physical analysis, launcher design, and RF power plant design. The physical analysis activity explores various approaches to enhance ECCD efficiency. The RF power plant design activity produced a conceptual design of a 100 MW class RF power plant. The launcher design activity presented the upper and equatorial launcher port of the JA DEMO tokamak vacuum vessel and analyzed the ECCD operation of each launcher. The result is the achievement of RF power deposition at the core of plasma for ECCD by selecting the proper injection angle and frequency.
Nonlinear Landau damping of electron Bernstein waves in MAST-U
Authors: Senstius Mads Givskov , Freethy Simon , Nielsen Stefan Kragh , Barnes Michael
Published: November 2024

The Mega-Amp Spherical Tokamak Upgrade (MAST-U) is preparing to investigate microwave based current drive using an advanced wave coupling scheme known as O-X-B at high power. The main goal is to assert if this is an efficient method for current drive in the future fusion demonstration power plant STEP. A model for the nonlinear wave-particle interaction nonlinear Landau damping (NLD) is presented. A relativistic, kinetic and electrostatic description is used. For MAST-U, NLD could lead to heating and current drive at the upper hybrid (UH) layer or at the electron cyclotron (EC) resonance of a substantially downshifted daughter wave produced by the wave-particle interactions. It is found that the typical treatment used for nonlinear waveinteractions fails at two critical points in the vicinity of the UH layer.
IMAS modelling of First Wall EC heat loads for the ITER rebaseline
Authors: Schneider Mireille , Stober Jörg , Preynas Mélanie , Carpentier-Chouchana Sophie , Deliege Quentin , Dubrov Maksim , Poli Emanuele , Sirinelli Antoine
Published: November 2024

This paper describes the modelling work carried out within the ITER Integrated Modelling and Analysis Suite (IMAS) [1] using the TORBEAM wave code [2] to estimate heat loads on the first wall (FW) from operating the Electron Cyclotron (EC) system in various scenarios of the ITER new baseline currently under preparation. These results provide guidance on how to best operate the EC system in terms of polarisation and operating launchers for the various phases of the Research Plan and of a pulse, to limit FW heat loads. Strategies to best protect the FW from EC power losses are also discussed.
Flux pumping studies and Ti peaking by q-profile shaping using ECCD in ASDEX Upgrade
Authors: Stober Jörg , Bock Alexander , Burckhart Andreas , Dunne Mike , Fable Emiliano , Fischer Rainer , Hölzl Matthias , van Mulders Simon , Poli Emanuele , Pütterich Thomas , Reisner Maximilian , Sauter Olivier , Schramm Raphael , di Siena Alessandro , Silvagni Davide , Zohm Hartmut ,   ASDEX Upgrade Team
Published: November 2024

On ASDEX Upgrade a prioritized ‘advanced Tokamak’ program has been run during the last two experimental campaigns, focusing on the effect of non-standard current profiles on the behavior of high beta plasmas. Two lines of non-standard (i.e. non-sawtoothing) q-profiles are followed: (1) plasma self-organization of centrally flat q-profiles (qmin ≈ 1) via ‘flux pumping’, here based on a naturally occurring continuous (1,1) mode and (2) externally shaped q-profiles with qmin > 1, allowing for more experimental freedom of the q-profile to be established. The advantages and requirements of both concepts are discussed. The invited presentation at the workshop focuses on specific effects of Electron Cyclotron Current Drive (ECCD). With respect to flux pumping it could be shown that increasing the plasma beta raises the flux pumping capability. More central coECCD can be redistributed if beta is increased. This is in line with qualitative theory. For the case with qmin > 1, it is shown that small variations of the ECCD profile can modify the peaking of the central ion temperature. For larger radii no significant changes of the kinetic profiles have been observed as the q-profile is changed. Hfactors have not exceeded 1.2, well below the assumptions of several models for steady state tokamak operation. To achieve these changes of q at larger radii we have used ctr-ECCD in the plasma center, increasing the ohmic current globally. The net effect of central ctr-ECCD and increased ohmic current is a strong off-axis current drive, allowing H-modes with Te ≈ Ti ≈ 8 keV and n¯e ≈ 6 · 1019m−3 ≈ 0.5 nGW at q95 = 4 to be run stationary with qmin ≈ 1.4. The design of these discharges was strongly supported by inter-shot model based optimization.
Overview of recent turbulence studies across multiple confinement modes at the ASDEX Upgrade tokamak using the Correlation Electron Cyclotron Emission diagnostic
Authors: Yoo Christian , Bielajew Rachel , Vanovac Branka , Schellpfeffer Jacob , Burke Willy , Conway Garrard , Rodriguez-Fernandez Pablo , White Anne ,   the EUROfusion WPTE Team,   the ASDEX Upgrade Team
Published: November 2024

This work presents an overview of recent and ongoing experimental measurements of core and edge turbulence across multiple confinement regimes using the Correlation Electron Cyclotron Emission (CECE) diagnostic at the ASDEX Upgrade (AUG) tokamak. A common goal among these investigations is to identify how the properties of the turbulent electron temperature fluctuations measured by CECE influence and regulate the unique transport characteristics of each confinement regime, including L-mode, I-mode, ELMy H-mode, and ELM-free H-mode. Optics and signal processing methods to aid in the analysis and interpretation of experimental turbulence results are also presented. These methods, and particularly the down-sampling and ensemble averaging method, are relevant to a wide variety of fusion and non-fusion applications.
Recent Results from Electron Cyclotron Emission (ECE) Radiometer diagnostics in the presence of Electron Cyclotron Resonance Heating (ECRH)
Authors: Siju Varsha , Pathak S.K. , Shukla B.K. , Tanna R.L. , Kumar R. , Ghosh J. ,   Aditya-Upgrade Team
Published: November 2024

Besides furnishing localized spatial and temporal electron temperature measurements, Electron Cyclotron Emission (ECE) diagnostics are routinely employed across various tokamaks for diverse physics investigations, encompassing MHD localizations, transport studies, and fluctuation measurements. Variations in the bulk of the electron distribution function manifest as alterations in ECE signatures, often attributable to the presence of fast electrons induced by auxiliary heating mechanisms such as Electron Cyclotron Resonance Heating (ECRH). This manuscript delves into the scrutiny of such interactions on ECE spectra leveraging a newly devised 16-channel ECE radiometer diagnostic. The manuscript delineates the impact of ECRH application, including pre-ionization and heating, resulting in ECE signal saturation and an expected rise in electron temperature (Te) respectively. Furthermore, the discourse explores instabilities potentially induced by high-energy electrons stemming from ECRH, focusing initial observations on runaway discharges characterized by relaxation oscillations in ECE, Soft X-ray (SXR), CIII, and Hα emissions. The backdrop of weakly ionized plasma with low electron density (ne) and temperature (Te), coupled with ECRH, fosters the generation of runaway electrons and corresponding relaxation oscillations in bulk plasma parameters. Additionally, a distinct surge in the ECE signature emerges upon cessation of the ECRH pulse, with no discernible variation in other bulk plasma parameters. Given that ECE signatures are susceptible to changes in both energy and pitch angle, this abrupt amplitude rise likely arises from Pitch Angle Scattering (PAS), potentially prompted by the sudden de-acceleration of fast electrons engendered by the ECRH pulse.
Design, Development and Characterization of Indigenously Developed High Temperature Black Body Source for Calibration of ECE Diagnostics
Authors: Sinha Abhishek , Mohanta Dusmanta , Parmar Neha , Pandya Santosh P. , Pathak Surya K.
Published: November 2024

The design, development, and characterization of a Silicon Carbide (SiC) based hightemperature black body source at 600 ºC for Electron Cyclotron Emission (ECE) measurements has been done. The design has been optimized for higher emissivity performance in 65-140 GHz frequency range using CST Microwave Studio. The innovative design features a pyramid-based structure, incorporating a heater and emitter surface, integrated with an electrical control system. The improvement in emissivity with variation in pyramid slant angle was analysed. The design was refined to ensure surface temperature consistency within a range of ± 15 ºC and rapid heating, taking less than 60 minutes to reach 600 ºC from room temperature. The developed black body calibration source was thermally characterized using IR camera for different set of temperatures and mean temperature distribution was determined. The microwave characterization of the calibration source has been performed in 65–220 GHz frequency range using Vector Network Analyser (VNA) and reflectivity of more than 20 dB has been obtained. The results highlight the synergy between advanced design methodologies, and precise engineering, leading to the development of an efficient SiC-based black body source. This research work not only contributes significantly to the field of engineering but also paves the way for enhanced accuracy and reliability in ECE measurements.
ITER ECH&CD Transmission Line Layout Development
Authors: Wolfe Zachary C. , Kaufman Michael C. , Shanmugasundaram Aravind , Hanson Gregory R.
Published: November 2024

A primary contributor to the effectiveness of the ITER electron cyclotron (EC) heating & current drive (H&CD) transmission line (TL) is the distortion of the waveguide which has a strong, direct correlation with power transmission efficiency and electromagnetic mode purity. Two main sources of distortion are the deflection of the TL due to operational loads and misalignment of the waveguide supports. To address these and other interdependent variables, the EC TL design focused on a holistic method to provide iterative simultaneous development of the system and microwave components. The process provided close, rapid interconnectivity between the prescribed subsystem requirements and the design activities being performed, including a detailed 3D configuration management model, a system structural finite element analysis, a thorough multi-sample Monte-Carlo system functional performance assessment, and individual microwave component designs & analyses. This paper intends to provide an overview of the first of these: the design development process of the TL layout. This includes investigating the inputs into layout optimization, the overall integration process, the interconnectivity with the other design activities, and their impacts on TL subsystem performance that ultimately resulted in the current baseline layout.
ITER ECH Transmission Line System Design and Status
Authors: Hanson Gregory R. , Wolfe Zachary C. , Kaufman Michael C. , Casal Natalia , Dukes Carl L. , Gandini Franco , Goodman Timothy P. , Hale Zackary P. , Henderson Mark A. , Schaich Charles R. , Shanmugasundaram Aravind , Takahashi Koji
Published: November 2024

The electron cyclotron (EC) heating & current drive (H&CD) system on ITER provides plasma heating by generating, transmitting, and launching high-intensity, high-frequency (170 GHz) electromagnetic wave energy steerable across the plasma cross-section. The transmission line (TL) subsystem connects the Matching Optics Unit (MOU) on each of the 24 gyrotrons to the 32 feed points in the four upper launchers and the 24 feed points in the equatorial launcher. Each TL must be able to operate at up to 1.2 MW of input power for up to 1 hour pulse lengths. The TL system contains 50 mm water-cooled corrugated waveguide, 90o miter bends, 140o miter bends, polarizer miter bend pairs, switches, expansion units, pumpouts, DC breaks, MOU-TL adapters, Radio Frequency (RF) loads, and isolation shutter valves. A detailed finite element analysis has been used to verify the thermo-mechanical performance of each component. The microwave performance has been analyzed using a 2-D electromagnetic code combined with a Monte Carlo code. This approach allows the impact of manufacturing and installation tolerances to be assessed and optimized to provide a high probability of achieving the system performance requirements. Prototypes of the waveguide and TL components have been fabricated and tested at high-power. Production contracts are now being issued for fabrication and delivery of the waveguide and components to ITER.
Environmental and energy issues in biodiesel production using palm oil from the interspecific hybrid OxG and Elaeis guineensis: a case study in Colombia
Authors: Mogollon Diego Ignacio Nieto , Venturini Osvaldo José , Batlle Eric Alberto Ocampo , González Aldemar Martinez , Munar-Florez David Arturo , Ramirez-Contreras Nidia Elizabeth , García-Nuñez Jesús Alberto , Borges Pedro Tavares , Lora Electo Eduardo Silva
Published: November 2024

In Colombia, in the last decade, the interspecific hybrid cultivar OxG, generated by a cross between American palm and African palm, has increased due to its tolerance to bud rot caused by Phytophthora palmivora. This study aimed to evaluate and compare the energy balance and environmental indicators of biodiesel production chains for both cultivars in Colombia. For this, an energy analysis was carried out to determine how energy is used in each process, as well as the palm energy per hectare. Also, a comparative analysis “cradle-to-gate” was made to verify the environmental performance of the genotypes studied. The functional unit was defined as 1.0 MJ of energy produced, and impacts were modeled using SimaPro v.8.0.3 software and quantified using the Impact 2002+ method. The results showed biodiesel from hybrid OxG reduced 6.2% the overall efficiency indicator of the system compared to biodiesel from E. guineensis. Life cycle CO2eq emissions of E. guineensis biodiesel were 12.5 g MJBD-1 (excluding carbon sequestration). In contrast, the CO2eq emissions of OxG hybrid biodiesel were 13.8 g MJBD-1. The life cycle efficiency indicators for biodiesel produced from OxG and E. guineensis showed a reduction in the fossil energy index of 26.9% and 19.7%, respectively.
Security risk prediction technology for power monitoring system under the integration of OT and IT
Authors: Zhu Zhennan , Jin Jingquan
Published: November 2024

As an essential force for economic advancement and social stability, the security of the power system has always been a concern. Therefore, the security risks of power monitoring systems are a research focus. This study proposes a prediction method that integrates IT and OT for the security risk prediction of power monitoring systems. A basic indicator system for security risks for analyzing risk data is constructed, the support vector machine regression feature elimination method for predicting security risks in IT Technology is used. The experiment showed that the accuracy of the support vector machine regression feature elimination method was 92.35%, which was 6.06% higher than the error back propagation algorithm, 3.19% higher than the support vector machine algorithm, and 0.77% higher than the regression feature elimination algorithm. The maximum testing accuracy of the support vector machine regression feature elimination method was 0.96, which was 0.1 higher than the support vector machine algorithm, 0.04 higher than the regression feature elimination algorithm, and 0.17 higher than the back propagation algorithm. Therefore, the support vector machine regression feature elimination method can accurately predict power monitoring systems and has higher accuracy compared with other algorithms.
Effect of Post Sizes and Citric Acid Treatment on the Bond Strength of Fiber Posts Using Self-Etch Resin Cement in Calcium Silicate–Based Sealer Treated Teeth
Authors: Klanliang Kittipit , Dewi Anat , Tangwattanachuleeporn Pradtana , Louwakul Phumisak
Published: November 2024

Objectives This study evaluated the effects of different post sizes and citric acid (CA) treatment on the bond strength of fiber posts cemented with self-etch resin cement in teeth obturated with calcium silicate–based sealer.

Materials and Methods Seventy mandibular premolars were collected and randomly distributed to either a control group (no sealer) or experimental groups obturated with calcium silicate–based sealer (iRoot SP). The experimental groups were classified by post sizes—1.25 mm (no. 1), 1.375 mm (no. 2), and 1.50 mm (no. 3)—and the irrigants used (distilled water [DW] or CA). Prefabricated fiber posts were fixed using NX3 self-etch resin cement. Push-out bond strength was tested in the coronal and middle sections of the roots.

Statistical Analysis The data were analyzed using a one-way analysis of variance (ANOVA), followed by a post hoc Duncan test.

Results In the coronal section, post size no. 1 with DW showed significantly lower bond strength compared to the other experimental groups (p < 0.05). In the middle section, the larger post sizes (nos. 2 and 3) with CA treatment resulted in a significant increase in bond strength compared to the control group (p < 0.05).

Conclusions iRoot SP negatively affected bond strength in the middle section of the canal. However, using larger post sizes (nos. 2 and 3) with CA treatment improved bond strength in the middle section.
Fluctuation surface conductivity of bulk superconductors
Authors: Cheishvili O. D.
Published: November 2024

A microscopic calculation of the fluctuation conductivity of a hollow cylinder in the region of the second critical current is presented. It is shown that under certain specially chosen conditions the Maki contribution to the conductivity can be comparable to the Aslamazov and Larkin contribution. The fluctuation conductivity of bulk specimens is investigated when the surface superconductivity is higher than the third critical field.
Low-temperature yield stress anomaly in single-crystal silver
Authors: Landau A. I. , Parkhomenko T. A. , Pustovalov V. V.
Published: November 2024

Temperature dependence of the yield point τ0(T) was studied in single crystals of 99.9%-pure silver within the range 1.6–77.3 °K. An anomaly was discovered which consists of a maximum and minimum appearing on the curve for this dependence. A theoretical explanation is offered for the anomalous dependence τ0(T), based on the assumption of two types of restraint on the migration of dislocation in crystals: thermogenic restraint caused by thermal fluctuation and athermogenic hindrances which are intrinsic in crystals or arise through other mechanisms than thermal activation. A computer-assisted comparison of theoretically derived τ0(T) with the experimentally obtained dependence shows satisfactory agreement.
Emission spectra of pure inert gas crystals
Authors: Fugol’ I. Ya. , Belov A. G. , Savchenko E. V. , Poltoratskii Yu. B.
Published: November 2024

Results of a detailed measurement of luminescence in inert-gas crystals at liquid-helium temperature are presented. The temperature dependence of the luminescence spectra of solid inert gases are studied from 2°K to the crystal sublimation temperature. The effect of small additions of oxygen, nitrogen, and carbon monoxide on the character of the crystal emissions is examined. Potential curves of the diatomic molecules in excited and ground states are analyzed, with the results supporting the excitation self-capture model with formation of a quasifree molecule in the inert crystal lattice. The process of oscillatory relaxation in various crystals is examined. The origin of long-wave ultraviolet radiation in pure crystals is considered.
Bulk viscosity and relaxation times of monatomic classical liquids
Authors: Mikhailenko S. A. , Dudar’ B. G. , Schmidt V. A.
Published: November 2024

The bulk viscosity of liquefied noble gases has been determined on the basis of acoustic experiments, and found to differ substantially from their shear viscosity. The relaxation times with respect to both bulk and shear strains have also been determined, while their relation to the stabilization time of equilibrium distributions in both the configuration region and in the pulse region of the phase space is analyzed here. It is shown that, when fluctuation effects resulting in a slower attenuation of autocorrelators and higher values of kinetic coefficients are taken into account, the agreement between theory and experiment improves even at rather small correlation radii and their corresponding characteristic times.
Quantum size effect in antimony-doped bismuth films
Authors: Komnik Yu. F. , Bukhshtab E. I. , Nikitin Yu. V.
Published: November 2024

The quantum oscillations in the resistance of pure bismuth films were studied before and after deposition of a thin antimony film and a homogenizing annealing. The period of the quantum oscillations in the resistance increases from ∼260 to ∼650 Å as the antimony is added, in accordance with a change in the parameters of the electron energy spectrum in bismuth antimony alloys.
Velocity and absorption of sound in superconductors
Authors: Borisyuk V. A.
Published: November 2024

The change of the velocity of low-frequency [ω,vq≪Δ(T)] sound in the superconducting state is found. It is established that the velocity of sound in superconductors decreases, and it is demonstrated that for sufficiently low temperatures (Δ/Ts2/v2∼0.1) the absorption of sound differs from the results obtained by Bardeen, Cooper, and Schrieffer (BCS). The results obtained by means of the diagram technique substantiate the dynamic equations in superconductors 2 over a wide temperature range.
X-ray studies of structure and thermal expansion in solid N2
Authors: Krupskii I. N. , Prokhvatilov A. I. , Érenburg A. I.
Published: November 2024

Results of an x-ray study of solid N2 in the temperature range 8–63 °K are presented. By analysis of Bragg reflections it is established that the upper limit of the possible displacement of molecules in α-N2 from centrosymmetric positions does not exceed 0.03 Ǻ. Using data on the temperature dependence of the lattice constant; the density, molecular volume, and coefficient of thermal expansion of the crystal are calculated. Correlation of molecular rotations was found to contribute to the thermal expansion of β–N2 near the phase transition temperature. The values of the heat capacity CV, the Griineisen coefficient, and isothermal compressibility are calculated. The behavior of the component CVrot produced by rotational motion of the molecules, is considered. On the basis of analysis of thermodynamic properties it is proposed that partial molecular ordering is preserved in β-N2.
The temperature dependence of magnetization in iron and nickel
Authors: Akhiezer I. A. , Syshchenko V. G. , Chudnovskii E. M.
Published: November 2024

It is shown that the s- and d-electron two-component Fermi liquid model with direct and indirect exchange forces describes the observed dependence of magnetization on temperature quantitatively in nickel, and qualitatively in the case of iron.
Effect of impurities, prestraining, and temperature on plasticity of superconductors
Authors: Natsik V. D.
Published: November 2024

Softening (enhancement of plasticity) of metals in the superconducting transition is analyzed as a function of concentration of impurities and deformational defects. This analysis is based on a theory, earlier suggested by the author, of transition induced metal softening which is valid when plasticity is determined by fluctuating dislocation motion over localized barriers generated by the defects mentioned. It is pointed out that the magnitude of the effect varies nonmonotonically with impurity concentration and plastic prestraining. The effect of impurities and deformations on the temperature behavior of softening effects is discussed.
Inelastic tunnel effect in thin films of condensed gases
Authors: Shklyarevskii Ο. I. , Yanson I. K. , Lysykh A. A.
Published: November 2024

Tunnel diodes containing a thin film of physically adsorbed gas in the barrier layer are investigated. Measurements were taken in a special deposition chamber at a temperature of about 5°K. Tunnel spectra of condensed ammonia, methane, and carbon dioxide are obtained, a number of vibrational bands are identified, and the phenomenon of asymmetry of the spectra relative to polarity reversal and the effect of traps on the form of the current-voltage curve are investigated. The effects observed on heating the junctions are studied.
Kinetics of defectons in quantum crystals
Authors: Pushkarov D. I.
Published: November 2024

The kinetics properties of defects are studied at low temperatures. The problem of the delocalization of a point defect and its transformation into a quasiparticle (defecton) is anlayzed. The delocalization time, the velocity of the delocalization wave front, and the defecton diffusion coefficient at T = 0 are found. The scattering of phonons and defectons by defectons is analyzed, and the corresponding cross sections are derived. In view of the small width of the defecton band (e≪mc2; c is the velocity of sound; m is the mass of a crystal atom), the cross section of defecton-defecton scattering may turn out to be anomalously large. For T≠0 the scattering of thermal phonons by defectons is essential. The scattering cross sectiop for acoustic phonons has a “Rayleigh” form σϕ∼k4 (k is the phonon wave vector). The diffusion coefficient, the mobility, and the other kinetic characteristics vary with temperature according to the power law ∼(Θ/8T)α, where α depends on the temperature interval and the defecton statistics. The diffusioncoefficient interpolation formula which takes account of scattering by defectons and phonons is in good agreement with experimental results.
Charge mobility in solid helium
Authors: Andreev A. F.
Published: November 2024

Mobility of ions in quantum crystals of solid helium is investigated. Due to the quantum nature of the crystals it proves possible to establish how the charge mobility depends on temperature and external electric field without appealing to any considerations as to the ion structure. At high temperatures the charge transfer is controlled by the inelastic scattering of long-wave vacancy waves by ions. At low temperatures, the inherent tunnelling of ions becomes important. This process may be accompanied either by scattering and/or spontaneous emission of phonons. A peculiar relationship between the mobility and the magnitude and direction of the external field is derived. The concentration dependence is also discussed.
Resonance sound absorption and acoustic quantum generation in hydrogen-containing niobium
Authors: Andronikashvili E. L. , Melik-Shakhnazarov V. A. , Naskidashvili I. A.
Published: November 2024

The observation of resonance sound absorption and emission in niobium containing elastic dipoles of hydrogen atoms is reported. The phenomena detected are related to the fact that the quantum properties of these centers are manifest at low temperatures.
The metallic behavior of hydrogen in palladium
Authors: Baranowski B. , Skośkiewicz T. , Szafrański A. W.
Published: November 2024

The special role of palladium as a host material in hydrogen–metal systems is pointed out. The criteria for the metallic behaviour of hydrogen in alloy systems are formulated. The main feature consists in an approximated state to that calculated for pure metallic hydrogen. Arguments for and against the «metallic hydrogen concept» for the palladium–hydrogen system are discussed. A special attention is paid to the band-structure calculations, superconductivity of palladium hydride and the partial volume of hydrogen measured in this system at high hydrogen concentrations. The importance of investigations at high pressures of gaseous hydrogen is shown.
The anomalous Debye–Waller factor of hydrogen in metals studied by incoherent quasielastic neutron scattering
Authors: Alefeld B. , Kehr K. W. , Springer T. , Lottner V. , Heim A. , Wakabayashi N.
Published: November 2024

In several transition metal–hydrogen systems, strong deviations of the quasielastic intensity lqe(Q) from a harmonic Debye–Waller factor have been observed (Q is the scattering vector). This behaviour is interpreted in terms of a correlation function of the protonic density which is characterized by two time scales: a, large one, determined by the mean time between two successive diffusive jumps: τ0, and a shorter one: τ1. Under the condition τ1≪τ0, the intensity lqe(Q) can be represented as a Fourier transform of the correlation function ∫p¯(r−r′)p¯r′)dr′. The bars mean an average of the density distribution of a single proton, ρ, over a time interval > τ0. The function Iqe(Q) was determined for hydrogen dissolved in niobium poly- and single crystals with a triple axis spectrometer. At elevated temperatures the results reveal an average density ρ¯(r) which is a superposition of a narrow distribution with a mean square amplitude of approximately 0.02 Ǻ2 and an extended distribution which spreads out over distances as large as the mutual distance between the interstitial sites in the Nb lattice. These results can be related to the high protonic self diffusion constant in such systems. Similar experiments are just being prepared for hydrogen in tantalum single crystals.
Quantum mechanically driven phase transition in solid helium
Authors: Meissner G.
Published: November 2024

In solid helium because of the small binding energy per particle (μ/κδ≃1°K) and the relatively large Debye temperature (ΘD≃20°K), the anomalous inequality holds for instance at about 30 atm even in the zero temperature limit (κB: Botlzmann’s constant). Using the Debye frequency ωD=κBΘD/ℏ as an estimate for an upper bound of phonon frequencies we find an extraordinary result that states of positive energy are accessible via high frequency vibrational excitations. For these reasons, we have investigated the highfrequency behaviour of the inverse of the displacement correlation function in quantum crystals at constant temperature T as a function of pressure P. Sum rule arguments are employed in order to investigate the phase transition from a regular crystal with one particle per lattice site at sufficiently high pressures P > PT to a crystalline state of possibly delocalized particles at P < PT. At zero temperature the transition pressure PT is determined by the ratio of zero-point energy to binding energy per particle which then drives the phase transition. Model calculations are presented to further elucidate the low-pressure phase.
Reaction-matrix calculation of ground-state energies, sound velocities, and phonon-dispersion relations of bcc helium
Authors: Namaizawa H.
Published: November 2024

A self-consistent reaction matrix approach is used to calculate the ground-state energy, velocity of sound and phonon dispersion spectrum of bcc solid helium. The ground-state energy is expanded in powers of the reaction-matrix K which is determined by solving a Schrödinger equation for an interacting pair of atoms. Phonons are identified as coherent transfer of excitation among the levels of atoms localized at their own sites. The solution of the two-body equation, which determines K, is, 1) approximated by an analytical correlation function and 2) solved numerically by expanding the wave function into partial waves. In both cases terms up to K2 are included to calculate the ground-state energies. It is found that the contribution from K2 term is important and improvement is reached in the volume dependence of energies of He3, especially in case 2). Phonon dispersion curves are also calculated in terms of K and in case of bcc He4 compared with experiments; the agreement is quite well, especially in 2). For bcc He3, sound velocities are presented as functions of molar volume. A better agreement with experiments is obtained again in 2) except for the transverse branch in the (1/2, 1/2, 0) direction. In conclusion we emphasize the importance of K terms in the ground-state calculations and the necessity of partial wave analysis for the two-body K matrix.
Theory of phase transitions in solid methanes
Authors: Maki K. , Kataoka Y. , Okada K. , Yamamoto T.
Published: November 2024

We have made a quantum statistical mechanical study of the phase transitions in solid CH4 and CD4 on the basis of an extended James-Keenan model. The calculation is carried out in the framework of the molecular field approximation in the truncated space spanned by rotational functions with J < 8 for equilibrium mixtures of three nuclear spin species A, T, and E. The transition between phases I and II is predicted to be of first order. In Phase II of solid methanes, three fourths of the molecules have the site symmetry D2d and the rest Oh. The rotational energy level schemes are worked out that allow us to systematically understand various kinds of experimental facts in Phase II including NMR, zero-point entropy, infrared and far infrared absorption, as well as neutron inelastic scattering.
The speed of sound in solidified inert gases
Authors: Bezuglyi P. A. , Tarasenko L. M.
Published: November 2024

The pulse method is used to measure the velocity of longitudinal and transverse ultrasound waves at a frequency of 1 MHz in crystals of neon (2–20°K), krypton (20–110°K), and xenon (40–150°K). The data obtained are used to determine adiabatic and isothermal elastic characteristics of the solidified inert gases, their Debye temperatures, and Griineisen coefficients. Comparison of the values found with calculated results allows evaluation of the suitability of various theoretical models for description of lattice dynamics in these crystals. Temperature dependences of sound speeds in reduced variables in the crystals studied were compared. It is shown that the temperature behavior of sound speeds obeys the law of corresponding states, with the deviations appearing in the cases of argon and neon being a manifestation of quantum effects connected with atomic zero point oscillations.
Parahydrogen in solid orthohydrogen: general theory and applications to the ortho-para conversion by neutron scattering
Authors: Diehl H. W. , Biem W.
Published: November 2024

a) General theory: We start from the Hamiltonian of a hydrogen crystal with fixed o-p composition written in creation and annihilation operators of local excitations. By introducing conversion operators which convert an o-H2 molecule into p-H2 and vice versa it is possible to formulate the Hamiltonian for crystal with various but constant compositions. The result can be generalized to include spontaneous conversion. It can also be used to formulate other operators, e. g., the operator of srataring 0f slow neutrons by hydrogen crystals; b) Neutron scattering: The cross section of the scattering with o-p conversion by phonons and librons in o-H2 crystals can be calculated in different approximations. Results: The main scattering effect can be understood in the simplest approximation which takes into account, in the Hamiltonian, only the conversion energy itself and neglects the changes in the intermolecular coupling by conversion. More involved approximations enlarge by a few percent only that part of the differential cross section by which librons are excited, since anisotropic forces between molecules cease to exist when an o-H2 molecule is converted into the p-H2 state.
Natural ortho–para conversion in solid H2 and D2
Authors: Milenko Yu. Ya. , Sibileva R. M.
Published: November 2024

The rate of ortho–para conversion in solid H2 and D2 is determined by intersection of neighboring molecules and the nature of the crystal vibrational spectrum. Natural orth—para conversion was studied in solid H2 and D2 for o—H2 concentrations between 65 and 75% at 4.2 and 13.7°K and for 20-90% of p-D2 at 4.2 °K. The conversion constant k in the equation dc/dt = −kc2 has been found to be k = 17×10−3h−1 in H2 at 4.2 °K. Within the range 4–14°K, the constant was found to be temperature independent which indicates that thermal phonons provide negligible contribution to the o–p conversion process at these temperatures. The concentration dependence of the conversion rate in D2 is close to linear, i.e., dc/dt = k' c with k' = 5.3×10−4h−1. The discrepancy between theory and experiment observed for o-p conversion in solid D2 (the calculated k is 1.8×10−3h−1) is attributed to the Debye phonon spectrum employed in the calculation. The agreement for H2 (k = 19×10−3h−1) is considered as accidental.