bluuebunny/crossref_metadata_2025 huggingface dataset:
Perovskite-based Photocatalysts for Hydrogen Production
Authors: Alam Umair , Singh Aradhana , Qamar M.
Published: December 2024

The utilization of chemical reactions that imitate photosynthesis holds promise for tackling the escalating energy crisis and the deteriorating conditions of the environment. Perovskite-based photocatalysts have attracted attention in the field of solar-driven hydrogen production due to their appropriate band structure, exceptional optoelectronic capabilities, and reliable stability. The perovskite materials possess an outstanding ability to respond to visible light, making them highly sought after as semiconductor photocatalysts for water splitting reactions and hydrogen production. The chapter begins with a concise summary of the advantages of perovskites in the context of hydrogen production, as well as an explanation of the fundamental concepts underlying the photocatalytic reactions. Further, the chapter highlights the synthesis methodologies employed to design highly effective perovskites, particularly metal oxides, by the implementation of diverse approaches, such as structural engineering and surface modification. These techniques aim to provide exceptional reactivity and practical applicability for photocatalytic H2 production. In addition, the chapter examines the challenges and potential future developments of materials based on perovskite, as well as the methods used to enhance their performance.
Metal Oxide-based Catalysts
Authors: Kageshima Y. , Domen K. , Nishikiori H.
Published: December 2024

Since the initial report of the Honda–Fujishima effect, various metal oxide-based photocatalysts have been studied, owing to the high catalytic activity and superior durability of these materials. The development of efficient photocatalysts requires the rational design of both the bulk and surfaces of these semiconductor particles. This chapter presents strategies that have been devised over the years to develop efficient ultraviolet light-responsive metal oxide photocatalysts, along with specific examples of highly efficient particulate metal oxide photocatalysts. These examples demonstrate that photocatalytic overall water splitting with an apparent quantum efficiency close to the ideal value of 100% in response to ultraviolet light has been achieved. Even so, the vast majority of solar radiation consists of visible light, and so the fabrication of efficient visible light-responsive photocatalysts is a prerequisite for achieving high solar-to-hydrogen energy conversion efficiencies. This chapter reviews various approaches to the design of visible light-responsive metal oxide photocatalysts and introduces recent concepts for solar hydrogen generation devices intended for future large-scale installations. Trends and progress in the field of photocatalyst research related to materials chemistry and chemical engineering are discussed, together with future challenges associated with the large-scale implementation of this technology.
Carbon-based Photocatalysts for Hydrogen Generation
Authors: Subramanian Yathavan , Minh Thang Le , Azad Abul K.
Published: December 2024

In recent decades, substantial progress has been made in the domain of greener renewable energy resources, addressing the urgent concern of depleting fossil fuel reserves. Consequently, the shift towards greener energy to replace traditional fossil fuels is essential, with hydrogen gas emerging as a significant eco-friendly fuel with a high calorific value. Among the various methods of H2 production, photocatalytic hydrogen production is drawing a lot of attention. In the last few decades, conventional photocatalysts, like TiO2, CdS, etc., have been utilized to generate solar fuels; however, they face limitations, such as photocorrosion and a wide band gap. Hence, scientists are actively striving to create a reliable, cost-effective and light-efficient photocatalyst using carbon-based materials. In particular, carbon nanotubes, carbon nitride, etc. have emerged as efficient photocatalysts for hydrogen production. Their exceptional properties, including high electrical conductivity, larger specific surface area, electronic structure and mechanical strength, make them ideal for photocatalytic H2 generation applications. This chapter thoroughly examines carbon-based photocatalysts for hydrogen generation, their types, properties, optimization strategies, recent advancements, and their vital role in sustainable hydrogen production, underscoring cost-effectiveness and ample supply for a greener future.
Metal Phosphide-based Photocatalysts for Hydrogen Production
Authors: Jayaraj Santhosh Kumar , Mokhtarifar Maryam , Mohan Sakar
Published: December 2024

The quest for sustainable and renewable energy sources has led to growing interest in the development of efficient photocatalysts for hydrogen (H2) production through water splitting. In recent years, transition metal phosphides (TMPs) have emerged as promising candidates for photocatalytic applications due to their unique electronic structure and superior catalytic properties. TMPs offer several advantages, including their Earth abundance, cost-effectiveness, and excellent catalytic activity, making them attractive for sustainable H2 generation. TMPs have recently gained attention as potential replacements for noble metal-based cocatalysts in the photocatalytic H2 generation process. In addition, various types of TMPs have been explored for this purpose, highlighting the structural and electronic properties that enhance their photocatalytic efficiency. The use and mechanism of the common TMPs, such as nickel phosphides (NiP), iron phosphides (FeP), cobalt phosphides (CoP), copper phosphides (CuP), and other phosphides based on Mo, W, Ni, and Fe, in photocatalytic H2 production are described. The chapter provides a concise overview of recent developments in the field, aiming to shed light on the potential of TMPs in addressing the global challenge of sustainable H2 production, and ultimately contributing to a cleaner and more sustainable energy future.
Transition Metal Dichalcogenide-based Photocatalyst Materials for Hydrogen Production
Authors: Hunge Yuvaraj M. , Yadav Anuja A. , Kang Seok-Won , Fujishima Akira , Terashima Chiaki
Published: December 2024

Transition metal dichalcogenides (TMDs) are an emerging class of two-dimensional materials with great potential for photocatalytic applications owing to their unique electronic and optical properties. TMDs possess a layered structure with strong in-plane covalent bonds and weak van der Waals interactions between the layers. This structure allows efficient charge transfer and separation, making TMDs efficient photocatalysts for various applications, including photocatalytic hydrogen production. TMDs have a distinct band structure with a direct bandgap, which enables the efficient absorption of visible light. TMDs can be synthesized using various methods, including chemical vapor deposition, exfoliation, solvothermal, and hydrothermal syntheses. To enhance the photocatalytic efficiency of metal oxide semiconductors, TMDs have been used as cocatalysts and are an alternative cocatalyst to costly noble metals, such as platinum and palladium. TMDs present additional active sites where hydrogen molecules can be adsorbed and activated. Several strategies have been employed to enhance the photocatalytic performance of TMDs by coupling with other semiconductors to create heterostructures and composites. Despite the great potential of TMDs, their use as photocatalysts faces challenges, including limited visible light absorption, relatively low carrier mobility, etc. This chapter discusses the utilization of MoS2-, WS2-, ReS2-, and NiS2-based photocatalysts for photocatalytic hydrogen production.
Carbon-based Electrocatalysts for Hydrogen Production
Authors: Gopalakrishnan Vishnu Nair , Shet Sachin M. , Subudhi Subham Kumar , H. R. Chandan , Balakrishna R. Geetha
Published: December 2024

The pursuit of efficient solutions for the production and utilization of clean and sustainable hydrogen energy has garnered significant interest. In pursuit of this objective, a viable and auspicious strategy involves the utilization of water electrolysis as a means of generating hydrogen. Currently, the most efficient electrocatalysts for the hydrogen evolution reaction (HER) are platinum group metals, which exhibit a low overpotential and can generate high cathodic current densities. Nevertheless, the exorbitant expense and limited availability significantly constrain their widespread implementation. Recent research has demonstrated the synthesis of transition metal compounds as efficient catalysts for the HER, serving as viable alternatives to Pt electrocatalysts. Nevertheless, up until now, the development of HER catalysts that exhibit high activity and minimal overpotential using readily available and affordable materials has proven to be a significant problem. In recent times, there has been a surge of interest among researchers due to the emergence of noteworthy advancements in carbon-based electrocatalysts that exhibit a low overpotential towards the HER. The catalytic efficiency of carbon-based catalysts can be augmented through the incorporation of transition metal nanoparticles as a principal component and the introduction of non-metal elements into the carbon framework. This strategy allows for the manipulation of the electronic state density of carbon, leading to the creation of novel active sites that facilitate the process of HER.
Metal Phosphide-based Electrocatalysts for Hydrogen Production
Authors: Li Shasha , Li Enze , Qiu Xunzhao , Wang Zehui , Guan Guoqing
Published: December 2024

Hydrogen is a promising and clean fuel for replacing fossil fuels to alleviate pollution issues. It can be produced with high purity in an eco-friendly and efficient manner via electrocatalytic water splitting. Exploring inexpensive and high-performance catalysts for the hydrogen evolution reaction (HER) is important for practical applications. Transition metal phosphides (TMPs) are recognized as attractive HER catalytic materials since they contain various active phases with tunable electronic structures. In this chapter, recent progress on TMPs developed as HER catalysts is presented. In particular, the main synthesis strategies, such as in situ generation, post-treatment, and electrodeposition methods, for preparing highly efficient TMP-based electrocatalysts are introduced, and the importance of electronic structure modulation, multicomponent hybrid engineering and microstructure regulation is emphasized. Finally, the challenges and prospects in development of TMP-based electrocatalysts for water splitting to produce hydrogen are highlighted.
Commercialization Status of Electrocatalysis, Photocatalysis and Photoelectrocatalysis Processes
Authors: R. Shwetharani , C. Lavanya , K. Brijesh , K. Vinothkumar , Geetha Balakrishna R.
Published: December 2024

Hydrogen is a clean, energy dense and renewable fuel. Producing hydrogen through an economically feasible and potentially scalable path is of great interest. The highly sustainable methods for hydrogen production are electrolysis, photocatalysis, and photoelectrocatalysis, all of which have advantages and disadvantages associated with transition of laboratory-scale processes to the commercial scale. This chapter discusses the commercial status of the electrolysis, photocatalysis, and photoelectrocatalysis processes. To begin, the chapter discusses conventional methods of hydrogen production, such as steam methane reforming, partial oxidation, and coal gasification, and then goes on to discuss the commercial status of electrocatalytic hydrogen production and its challenges, economic viability, and competitiveness. Furthermore, the commercial status of the photocatalysis and photoelectrocatalysis processes are also discussed.
Green Applications of Electrochemical Biosensors
Authors: Bilge Selva , Bakirhan Nurgul K.
Published: December 2024

Biosensors play a crucial role in various domains due to their ability to accurately and sensitively detect and quantify biological substances. They are extensively used in medical diagnostics for identifying ailments such as infectious diseases, cancer, diabetes, and cardiovascular disorders, enabling timely intervention. Moreover, biosensors serve as essential tools for monitoring environmental contaminants such as heavy metals and pesticides, aiding in risk identification and environmental condition evaluation. However, the detection performance of biosensors heavily relies on their selectivity, which is influenced by the chemistry of electrode surfaces. Recent research focuses on modifying electrode surfaces with various nanomaterial combinations to enhance detection performance. Electrode modifications, including the addition of stable coatings, enhance biosensor stability and resistance to harsh conditions. Accelerated electron transfer kinetics have been observed in electrodes modified with certain semiconductor nanoparticles, further improving biosensor performance. The growing popularity of modified electrodes has led to increased interest in greener approaches for biosensor development. Green synthesis methods offer environmentally friendly alternatives by utilizing natural sources to produce biocompatible and sustainable nanomaterials. These methods reduce dependence on harsh chemicals, minimize environmental impact, and enhance the biocompatibility, affordability, and sustainability of biosensors. However, challenges such as variable reproducibility and scalability issues persist, requiring further investigation and optimization. Understanding the mechanisms and roles of green synthesis techniques in biosensor applications is crucial for large-scale implementation. Research in this area contributes significantly to advancing the use of green synthesis-based biosensors.
Theoretical Characteristics of Biosensing Technology
Authors: Nandi Santosh , Adimule Vinayak , Sharma Vandna , Kumar Pankaj , Barmavatu Praveen
Published: December 2024

The word “biosensor” describes a potent and cutting-edge analytical tool with a biological sensing element that has a wide range of applications in biomedicine, drug development, diagnostics, food safety and processing, environmental monitoring, defense, and security.1 An electrical signal can be produced from a biological reaction using an integrated receptor–transducer device called a biosensor. Due to the numerous applications of biosensors in healthcare and disease detection, environmental monitoring, food and water quality monitoring, and medication administration, biosensor design and development have gained significant attention from researchers and scientists in the last ten years. Biosensing technology plays a pivotal role in various fields, such as healthcare, environmental monitoring, and food safety. This chapter provides a theoretical exploration of the fundamental characteristics of biosensing technology. Beginning with an overview of the principles underlying biosensing, including biomolecular recognition and signal transduction mechanisms, this chapter delves into the theoretical foundations of biosensing devices. Considerations for optimizing these characteristics are explored, along with theoretical models for analyzing sensitivity, selectivity, and detection limits. This chapter also discusses prospective developments in sensitivity, specificity, and miniaturization, as well as new trends and prospects in biosensing technologies. Overall, this chapter offers valuable insights into the theoretical underpinnings of biosensing technology, paving the way for further research and innovation in this critical field.
A Comparative Study of the Application of Biosensors in Human Health
Authors: Gupta Urvashi , Yadav Sapna , Saini Kalawati , Woollam Mark , Agarwal Mangilal , Maity Dipak
Published: December 2024

This chapter delves into the pivotal role that biosensors play in transforming healthcare practices. Biosensors, comprising bioreceptors, transducers, and signal processors, detect and measure biological substances, offering high sensitivity and specificity in various healthcare applications. With applications ranging from disease detection to personalized medicine, they have revolutionized diagnostic practices, enabling early disease detection and tailored treatment regimens. This chapter explores the significance of biosensors in various healthcare sectors, highlighting their unparalleled accuracy and rapid detection capabilities. Despite their potential, biosensors face challenges related to sensitivity and cost-effectiveness, underscoring the need for critical evaluation and comparison of various approaches. Through a comprehensive analysis of biosensor applications in disease detection, metabolic diseases, treatment monitoring, breath-based diagnostics, DNA/RNA diagnostics, retinal prosthesis, phenotypic cancer diagnostics, medical mycology, and MRI contrast imaging, this chapter aims to provide insights into their efficacy, feasibility, and potential impact on healthcare delivery. By contributing to ongoing discussions in the field, this chapter will inspire further research and innovation, advancing the use of biosensors as transformative tools in improving healthcare delivery and patient outcomes.
Toxicity, Safety, and Disposal of Developed Biosensors
Authors: R. Rajkumar , S. Kalaiarasi , P. Karpagavinayagam , C. Vedhi
Published: December 2024

A biosensor is a device with integrated receptors and transducers that can transform a biological response into an electrical signal. Over the past decade, researchers have focused on designing and developing biosensors for various purposes, including health care, disease detection, environmental monitoring, water and food quality monitoring, and drug delivery. Biosensors are a significant tool for food analysis. Food safety poses a growing concern for human health worldwide. Improving analytical procedures and methodologies is crucial for ensuring food safety. Electrochemical sensors offer a unique possibility to achieve sensitive, precise, rapid, and portable food safety detection. The assessment of toxicity in water streams, wastewater, and polluted sediments is a critical component of environmental pollution monitoring. Evaluating biological effects using a quick, sensitive, and cost-effective method provides specific information for ecotoxicity assessment. With the unprecedented deterioration of environmental quality, the rapid recognition of toxic compounds is paramount for in situ real-time monitoring. Recently, microbial fuel cell (MFC)-based biosensors have drawn increasing interest due to their sustainability and cost-effectiveness, with applications ranging from monitoring anaerobic digestion process parameters to detecting water quality [e.g., chemical oxygen demand (COD) and biochemical oxygen demand (BOD)]. The release of chemicals into water systems has led to pollution in many parts of the world, posing threats to human health and aquatic ecosystems. This chapter presents the progress made in developing electrochemical biosensors for environmental toxicants (pesticides and heavy metals) over the past seven years.
Overview of the Catalytic Chemistry of Metal Complexes
Authors: Kojima Takahiko
Published: December 2024

Catalysts promote targeted reactions by providing new reaction pathways through the formation of specific intermediates to lower the potential barriers of the reactions, in place of conventional reaction pathways with high activation barriers. In this chapter, the basic concepts of catalysis are described, including the definition and classification of catalysts, together with their historical background. In addition, typical catalytic mechanisms are described for oxidative and reductive reactions.
Oxidation of Inert Substrates by Metalloenzymes
Authors: Suzuki Kazuto , Shoji Osami
Published: December 2024

In nature, a vast number of oxidative enzymes that utilize metal ions as their active centers exist, exploiting the properties of these metal ions to oxidize substrates under mild conditions. Among these metalloenzymes, cytochrome P450 (P450) is of particular interest due to its ability to hydroxylate inert organic substrates, suggesting its potential use as a catalyst. However, P450s capable of hydroxylating the desired substrates do not always naturally exist, and often, a conversion of substrate selectivity is necessary. This article will discuss ‘how to convert the natural substrate selectivity of P450’ from a chemical perspective.
Integration of Metal Nanoparticles and Metal–Organic Frameworks for Composite Catalysts
Authors: Kobayashi Hirokazu , Kitagawa Hiroshi
Published: December 2024

Hybrid materials composed of metal nanoparticles and metal–organic frameworks (MOFs) have attracted much attention in many applications, such as enhanced gas storage, catalytic, magnetic and optical properties, due to the synergistic effects between the metal nanoparticles and MOFs. In this chapter, we describe our recent progress in MOF-covered metal nanoparticles (metal@MOF) for catalytic applications focusing on CO oxidation, water gas shift and CO2 hydrogenation reactions for methanol synthesis. We also present novel one-pot synthesis methods for the preparation of composite materials, including Ni@Ni2(dhtp) (H4dhtp = 2,5-dihydroxyterephthalic acid) (MOF-74).
Nitrogen Fixation
Authors: Tanabe Yoshiaki , Nishibayashi Yoshiaki
Published: December 2024

Synthetic ammonia production using nitrogen gas in the atmosphere and hydrogen gas derived from fossil fuels has been the most important, as well as the most primary energy-consuming, process in the modern chemical industry. However, organisms have fixed nitrogen gas to obtain nitrogenous biogenic substances essential for life at ambient conditions for billions of years. Since the mid-20th century, a great number of investigations have been carried out for the development of stoichiometric conversions of dinitrogen into ammonia or other nitrogen-containing compounds at ambient temperatures and pressures by using molecular transition metal complex compounds. Especially in recent years, remarkable progress has been made in the use of molecular complex catalysts in the reduction of dinitrogen to obtain ammonia, hydrazine, silylamines, or other nitrogen-containing compounds at ambient temperatures and pressures. Turnover frequencies for the catalytic formation of ammonia have now surpassed enzymic activities of biological nitrogen fixation.
Catalytic Reactions by Metal Clusters
Authors: Mashima Kazushi , Tsurugi Hayato , Nagae Haruki
Published: December 2024

Multiple metal cluster complexes supported by alkoxide or carboxylate ligands as well as oxo, imido or nitride, and hydride serve as unique and intrinsic catalysts with peculiar reactivity and selectivity based on the concerted catalytic performance of two or more proximately arranged homo or hetero metals. This chapter highlights the catalytic reactions of these clusters for Lewis acid–base reactions, oxidation reactions, radical reactions, etc.
CO2 Reduction Using Metal Complexes as Photocatalysts
Authors: Tamaki Yusuke , Ishitani Osamu
Published: December 2024

In this chapter, photocatalytic systems for the reduction of carbon dioxide (CO2) using metal complexes are discussed. To construct efficient photocatalytic CO2 reduction systems, two functions, i.e., redox photosensitizer and catalyst, are required. Metal complexes displaying visible-light absorption and long lifetimes in the excited states might be suitable for redox photosensitizers and redox-active metal complexes having a labile ligand forming a vacant site to activate CO2 can possibly be used as catalysts. Simple mixed systems of them photocatalyze the reduction of CO2. In addition, supramolecular photocatalysts in which they are linked via covalent bonds are also introduced.
A metal organic framework, UiO-66-NH2, based on a molybdenum Schiff base complex for the efficient electrochemical determination of diphenoxylate
Authors: Saeednia Samira , Rezaeinasab Masoud , Iranmanesh Parvaneh , Abbasi Razgaleh Sobhan
Published: December 2024

Diphenoxylate, an agonist and opioid agent, is applied to enhance the activity of the circular muscle of the intestine. Herein prepared a novel electrochemical sensor for the determination of diphenoxylate.
Concurrent ultrafast twisting and proton transfer photoreactions in new pyrano[2,3-c]pyrazole derivatives
Authors: Navickas Marius , Gineitis Karolis , Urbonavičius Arminas , Krikštolė Sonata , Martynaitis Vytas , Arbačiauskienė Eglė , Dagilienė Miglė , Šačkus Algirdas , Vengris Mikas
Published: December 2024

Pyrano[2,3-c]pyrazole derivatives are a class of compounds exhibiting dual solvent-dependent fluorescence.
Translational paradigm of MXene nanocomposites: biophysical advancements to modern applications
Authors: De Sriparna , Naser Shaikh Sheeran , Nandi Aditya , Adhikari Arpita , Prasad Arbind , Sarkar Kunal , Sinha Adrija , Verma Sushil Kumar , Dutt Ateet , Chattopadhyay Dipankar , Kaushik Nagendra Kumar , Ghosh Aishee , Verma Suresh K.
Published: December 2024

The expanding potential of 2D MXenes opens up promising avenues for flexible biomedical applications.
Small-angle neutron scattering differentiates molecular-level structural models of nanoparticle interfaces
Authors: Wu Yujie , Liu Xindi , Radulescu Aurel , Porcar Lionel , Krause-Heuer Anwen , Jiang Hanqiu , Yang Hua , Ke Yubin , Darwish Tamim , Luo Zhi
Published: December 2024

Small-angle neutron scattering can be utilized to distinguish structural models of nanoparticles with molecular- and Å-scale differences.
Tuneable and degradable thermosets possessing dynamic aliphatic disulfide bonds via stereoselective thiol–yne polymerisation
Authors: Giannantonio Daniele , Brandolese Arianna , Dove Andrew P.
Published: December 2024

Degradable thermosets with cis/trans-dependent thermomechanical properties developed using nucleophilic thiol–yne addition.
Role of exciton delocalization in chiroptical properties of benzothiadiazole carbon nanohoops
Authors: Kovida Kovida , Malinčík Juraj , Cruz Carlos M. , Campaña Araceli G. , Šolomek Tomáš
Published: December 2024

A strong chiroptical response in chiral organic materials depends on the extent of delocalization of the exciton.
Synthesis of novel diesters as potential fuel oxygenates and surfactants of renewable origin from carbohydrate-derived 5-(chloromethyl)furfural
Authors: Yadav Sandeep Kumar , Dutta Saikat
Published: December 2024

5-(Chloromethyl)furfural (CMF) has received enormous interest over the past two decades as a carbohydrate-derived platform chemical for synthesizing organic chemicals of commercial significance.
Enhancing the monitoring capability of acoustic measurement points: An optimization method for the layout of acoustic measurement points for low‐frequency transformers
Authors: Zhao Tao , Zhang Shijie , Yang Jiajun , Lin Haofan , Wang Bowen , Yang Zhi
Published: December 2024

The acoustic signals in the operation of low‐frequency transformer have the state information of the body, which can be monitored online by arranging acoustic measuring points. An optimization method for the layout of acoustic measuring points for low‐frequency transformers is proposed in this study. First, a model of the low‐frequency transformer acoustic field is constructed by measuring the environmental size of the transformer acoustic field. Then, the virtual acoustic source measured by the transformer acoustic signal is input into the model, and the time‐varying acoustic pressure in the acoustic field is calculated. Finally, the spectral correlation coefficients between the acoustic signals at the candidate measurement points and the virtual acoustic sources are calculated to evaluate and improve the layout of the measurement points for the low‐frequency transformer. The method in this study was used to improve the layout of acoustic measurement points for the low‐frequency transformer in the frequency conversion station in Hangzhou. The results show that the method can effectively evaluate the monitoring ability of the acoustic measurement points on the overall acoustic state of the transformer in different positions. The study provides a reference for the layout optimization of the acoustic online monitoring device for low‐frequency transformers.
The colonial republic of psychoanalysis: how psychoanalysis polices the psychic sovereignty of “Others”
Authors: Sheehi Stephen , Sheehi Lara
Published: December 2024

This article uses a scholarly case to analyze how psychoanalytic soft power is extended to govern and regulate the “psychic sovereignty” of “non-normative” subjects, especially racialized, gendered and sexualized subjects in, from and of the Global South. In using an example from the ways psychoanalysis circulates within France (in particular within contemporary debates of what constitutes someone who is truly “French”), we consider how the “French intellectual tradition” mobilizes -despite its critique of them--universalizing concepts of secularism and citizenry to shore up, what we call, the colonial republic of psychoanalysis. Psychoanalysis itself is a formation that collaborates and colludes with colonial power (especially in its most liberal form) through its claim to the right over the psychic sovereignty of both individuals and nations who are in proximity to French colonial and neocolonial rule. Through close critique of the recent work of Élisabeth Roudinesco (and a handful of others) as a generalized but accurate case study, this article considers how psychoanalysis and psychoanalysts police sovereignty and “innocently” lodge themselves in liberal state discourse to control, manage and designate what psyches, bodies and subjects are deserving of empathy, rights, and psychological consideration. We explore how psychoanalysis as a normative method and practice designates who is perverse and who is deviant, who are genuinely good and bad objects, and is worthy of saving or worthy of expelling.
Ultrasonic propagation velocity in helium-hydrogen mixtures
Authors: Pashkov V. V. , Konovodchenko E. V.
Published: December 2024

A pulse technique is employed to measure the ultrasonic propagation velocity in solutions of helium in liquid hydrogen in the temperature region T = 18–30° K at pressures up to 110 atm. The adiabatic compressibility is obtained. The experimental results are analyzed in terms of a variant of perturbation theory which takes into account the quantum properties.
Fluctuation restoration of adiabaticity in nonlinear dynamics of superconductors
Authors: Nazarov Yu. V. , Éliashberg G. M.
Published: December 2024

It is shown for thin (⪡ξcor) gapless superconductors placed in an alternating magnetic field parallel to the surface of the specimen that for some forms of the periodic field the change in Δ is deeply nonadiabatic. Adiabaticity is restored only when fluctuations cannot be neglected. A scheme is developed for including nonstationary fluctuations based on the Fokker–Planck equation. The conditions under which the nonadiabatic regime is realized are estimated, some temporal correlation functions are calculated, and the most probable form of the nucleus of the superconducting phase is determined.
Vortex interaction with the boundary of anisotropic superconductors
Authors: Grishin A. M.
Published: December 2024

The Green’s function is found for the magnetostatic problem with a plane boundary between two anisotropic superconducting half-spaces. Abrikosov vortex pinning by a bicrystal boundary is investigated.
Nonlinear effects in parametric excitation of paramagnetic ions in a crystal with rhombic symmetry
Authors: Zvyagin A. A. , Frishman A. M. , Tsukernik V. M.
Published: December 2024

An exact quantum approach is used to investigate the low-temperature behavior of a system of paramagnetic ions of spin S = 1 and S = 3/2 under the parametric action of an rf magnetic field. The field is taken into account in the resonance approximation. It is shown that allowance for the finite value of the spin leads to resonance saturation, as a result of which the magnetization oscillates with a finite amplitude.
Effect of radiation defects and implanted ions on the superconducting properties of vanadium films
Authors: Kolin'ko A. E. , Sidorenko A. S. , Tishchenko L. P. , Fogel' N. Ya.
Published: December 2024

The change in the critical parameters of superconducting vanadium films under irradiation with helium ions is studied. It is found that implanted inert gas impurities and radiation defects have the same effect on the critical temperature Tc and the upper critical field Hc2 of vanadium. The decrease in Tc is due to a change in the characteristics of the electronic spectrum of vanadium due to disordering. The irradiation-induced increase in Hc2 is explained qualitatively and quantitatively by the theory of type II superconductors. A small change in the critical parameters, due to the proximity effect, is also observed when a thin surface layer of the films, which is small compared to the film thickness, is irradiated.
Influence of defects on the quantum motion of dislocations in a crystal relief
Authors: Petukhov B. V. , Sukharev V. Ya.
Published: December 2024

The influence of randomly distributed defects on the tunneling mobility of dislocations in a crystal relief is calculated. The defect-related change in the temperature interval in which quantum effects are manifested is determined.
Manifestation of the critical state in the softening of type-II hard superconductors
Authors: Dotsenko V. I. , Sirenko V. A.
Published: December 2024

We have investigated the possibility of finding the true magnitude of softening in type-II hard superconductors, using a reverse magnetic field to eliminate the trapped flux. The results are interpreted within the framework of the critical state model.
Magnetic excitations localized in space and periodic in time
Authors: Babich I. M. , Kosevich A. M. , Manzhos I. V.
Published: December 2024

A one–parameter localized solution to the Landau-Lifshitz equation for a one–dimensional magnetization soliton in an easy-plane ferromagnet in a magnetic field oriented along the anisotropy axis is obtained. This solution corresponds to oscillations of the magnetization in a soliton whose center executes periodic motions, but which does not, on the average, undergo displacements. The solution parameter is the oscillation frequency ω of the magnetization vector. It is shown that, for imaginary values of the parameter ω, the solution describes the scattering of two magnetization-vector rotation waves. The soliton energy is computed, and its quasiclassical quantization is carried out. The energy spectrum obtained as a result of the quasiclassical quantization is compared with the spectrum obtained in the exactly soluble quantum-mechanical problem.
Detection of exchange modes in the quasi-two-dimensional antiferromagnet (NH3)2(CH2)3MnCl4
Authors: Stepanov A. A. , Kobets M. I. , Zvyagin A. I.
Published: December 2024

The antiferromagnetic resonance of the quasi-two-dimensional antiferromagnet (NH3)2(CH2)3MnCl4 has been investigated in the frequency range 20–180 GHz at helium temperature. In addition to the acoustic branches we have detected optical (or exchange) branches in the AFMR spectrum and have determined their frequencies.
Effect of energy relaxation in a superconductor on the response of an rf squid
Authors: Dmitrenko I. M. , Khlus V. A. , Tsoi G. M. , Shnyrkov V. I.
Published: December 2024

We consider how energy relaxation in a superconductor affects the macroscopic quantum interference effects that occur in a ring closed by a Josephson junction. It is demonstrated experimentally that the behavior of such a ring when the external parameters are altered differs radically from the properties suggested by the resistive model. The effects revealed may well be explained by the microscopic theory which takes account of the energy relaxation time of excitations in the superconductor.
The de Almeida–Thouless anomaly in the phase transition in the asperomagnetic state
Authors: Ginzburg S. L.
Published: December 2024

In systems with a continuous symmetry group and with competing ferromagnetic and antiferromagnetic interactions phase transitions can occur; first, from the state of collinear ferromagnetism with ρ = 0 (ρ is the Ewald–Anderson parameter for magnetization perpendicular to the spontaneous magnetization or to the external magnetic field) to the asperomagnetic state with ρ ≠ 0, and, second, a transition to a degenerate state.

It is shown that the lines of these two phase transitions coincide. This fact is quite natural since the asperomagnetic state is, in a sense, a transverse spin glass and a phase transition to a spin glass is always accompanied by degeneracy.
Macroscopic quasiparticles in an 3He–4He quantum crystal
Authors: Anisimova O. P. , Vardanyan G. A. , Sedrakyan D. M. , Saakyan A. S.
Published: December 2024

Vacancions, which constitute macroscopic quasiparticles, are formed in an 3He–4He solid solution in the temperature range ε,J≪T≪Δ (J is the exchange interaction energy, ε is the characteristic interaction energy of 4He atoms, and Δ is the width of the vacancy energy band).

In the range of concentrations c = n3/n4≪1 (n3 and n4 are the numbers of 3He and 4He atoms, respectively) a vacancion in a sphere with a macroscopic radius R is surrounded only by 4He atoms while in the range of concentrations c∼1 a vacancion is a macroscopic region that contains only 3He atoms, whose spins are polarized.

These quasiparticles, obviously, play a substantial role in the thermodynamic and magnetic properties of a 3He–4He crystals.
Phase transition between commensurate and incommensurate phases in a lattice and their formation
Authors: Fogel’ N. Ya. , Cherkasova V. G.
Published: December 2024

A number of anomalies have been detected in the behavior of the critical current of superconducting films placed in a parallel magnetic field. The dependence of the critical current Ic on the field is oscillatory in nature, and in a certain range of fields and temperatures Ic does not depend on the temperature.

It is shown that the anomalous behavior is observed only in films with smooth, mutually parallel surfaces. The laws discovered are explained on the basis of concepts concerning a phase transition between commensurate and incommensurate phase in a lattice of vortices and their images.

The commensurate phase corresponds to the formation of a regular periodic lattice, in which case the fixed period of the lattice of images that is determined by the thickness of the film is equal to or a multiple of the period of the vortex lattice in the film, which is determined by the value of the external magnetic field.
Hydrodynamics of a superfluid in the weak interaction model
Authors: Lavrinenko N. M. , Peletminskii S. V. , Slyusarenko Yu. V.
Published: December 2024

The equations of the hydrodynamics of a superfluid with υk – uk≠0 (υk and uk are the velocities of the superfluid and normal components) are derived with allowance made for dissipative processes. It is shown that in this case the system is described by 14 kinetic coefficients. The low-temperature asymptotic forms of all these coefficients for the υk− uk≠0 case are considered.
Paraconductivity of V3Ge in a magnetic field
Authors: Marchenko V. A. , Nikulov A. V.
Published: December 2024

The magnetic-field and temperature dependences of the excess electrical conductivity in V3Ge have been investigated in the region of field intensities H ≳ Hc2. The data obtained are compared with the results of the Ami-Maki theory and the theory based on the Hartree approximation. The sharp deviation of the experimental dependence from the theoretical curve in the region of high magnetic field intensities is related to a transition from the one-dimensional state into a mixed state.
Stable three-dimensional small-amplitude solitons in magnetic materials
Authors: Ivanov B. A. , Kosevich A. M.
Published: December 2024

We investigate three-dimensional centrosymmetric soliton solutions of an equation of the nonlinear Schrödinger type, but which, unlike the standard situation, contains fourth (rather than second) derivatives with respect to the coordinates. An equation of this type affords a macroscopic description of quasiparticles whose effective mass becomes infinite. We show that, unlike the standard situation, three-dimensional small-amplitude solitons representing bound states of a large number of quasiparticles can exist in such a system. The energy associated with one quasiparticles in the bound state is smaller than the energy of a continuous-spectrum quasiparticle, evincing stability of the soliton.
X-ray studies of solid n-H2
Authors: Krupskii I. N. , Prokhvatilov A. I. , Shcherbakov G. N.
Published: December 2024

The results of precise x-ray studies of normal hydrogen from 2°K to the triple point are reported. Temperature dependences of the lattice parameters, molar volume, linear and volume expansion coefficients of n-H2 have been obtained. An increasing contribution to the thermal expansion of the crystal was found with decreasing temperature which is due to the presence of a rotational subsystem in n-H2. It is shown that near the melting point the thermal expansion of n-H2, similarly to that of p-H2, is essentially anisotropic. The thermodynamic properties of n-H2 are analyzed. The results obtained are evidence of the existence of an isomorphic phase transition in solid n-H2 in the premelting region.
Effect of the superconducting transition on slip and twinning in indium and its alloys
Authors: Kuz’menko I. N. , Lubenets S. V. , Pustovalov V. V. , Fomenko L. S.
Published: December 2024

Single crystals of pure indium and In–Pb alloys (6 and 8 at.% Pb) were tested under compression at a constant rate ε˙=10−5−10−4 sec at temperatures of 0.48 and 1.7°K in order to study the effect that the state of the specimen has on the yield point in slip and on the twinning stress, as well as the effect of the N–S transition on the flow stress in slip and twinning. The state of the electron subsystem has been found to have a strong influence on the parameters of plastic deformation under slip (monotonic or stepwise). It is shown that in In-Pb alloys, which are deformed up to ε ≈ 6% solely through twinning, neither the twinning stress nor the flow stress depends on the state of the specimen.
Quantum diffusion in solid solutions of helium isotopes with strong localization of 3He atoms
Authors: Mikheev V. A. , Mikhin N. P. , Maidanov V. A.
Published: December 2024

Using NMR, we have measured the diffusion coefficient D of 3He atoms in solid 4He over a wide range of 3He concentration, densities, and temperatures. We have found that in the region of the low-temperature plateau the diffusion coefficient decreases sharply to D≈3 · 10−12 cm−2/sec. The result indicates a strong localization of 3He atoms in the hcp phase of 4He; this localization is lifted by phonon-stimulated quantum diffusion, in total agreement with the predictions of the Kagan theory. Our analysis of the contributions of different mechanisms to 3He diffusion eliminates the contradictions in the treatment of 3He vacancy diffusion. The diffusion of 3He has been investigated near the critical concentration and the parameters of the critical behavior of D have been found. For the first time we have observed diffusion which is essentially independent of the pressure and this is explained in terms of the dipole–dipole diffusion model.
Spin–spin relaxation in a one-dimensional antiferromagnet with parallel pumping
Authors: Kleiner B. Z.
Published: December 2024

We obtain the kinetic equation for the spin excitation distribution function with a one-dimensional X-Y model with longitudinal pumping. Two times for the excitations to relax to the stationary distribution are investigated, and their temperature dependences are found.
Luminescence of copper in a xenon cryomatrix
Authors: Samovarov V. N. , Fugoľ I. Ya. , Khomenko S. I.
Published: December 2024

We have studied the photoluminescence spectra of copper atoms and molecules isolated in a xenon cryomatrix when they are excited into their lowest excited states. The experimental data demonstrate that the excitation of the atom leads to formation of a multiatomic excimer (CuXe12) in the matrix. The emission spectrum of the copper molecule is controlled by a two-quantum excitation mechanism in the dissociating molecule. The two-quantum process leads to population of excimer states of the same nature as those found upon excitation of the atom.
Influence of the phase transition in CsDy(MoO4)2 on the electronic spectrum of the Dy3+ ion.
Authors: Eľchaninova S. D. , Zvyagin A. I.
Published: December 2024

Comparison of the spectra of the two phases, above and below the first order phase transition (∼ 40 °K, has shown that the chane in the small j terms is insignificant, but the spectra of the lowest terms (6H15/2, 6H13/2, and 6H11/2) differ strongly. From the temperature dependence of the intensities of the additional bands in the spectrum we have determined the low-frequency electronic and phonon levels of cesium dysprosium molybdate in the high- and low-temperature phases of the crystal. We propose that acoustic phonons participate in the phase transition.
Spin diffusion in solid 3He–4He solutions
Authors: Slyusarev V. A. , Strzhemechnyi M. A.
Published: December 2024

The Kubo method is used to calculate the spin-diffusion coefficient and the spin–spin relaxation time, due to the dipole–dipole interaction of the nuclear magnetic moments of a dilute magnetic system. A comparison is made with the results of NMR experiments on measuring the diffusion coefficient in solid solutions of helium isotopes.
The effect of the anisotropy of the Fermi surface on measured characteristics of the electron energy spectrum of tungsten
Authors: Nemoshkalenko V. V. , Zhalko-Titarenko A. V. , Antonov V. N.
Published: December 2024

Calculation of the Fermi surface and of the electron-phonon coupling constant in W has been carried out within the McMillan approximation by the relativistic augmented plane wave method. A comparison is made between the results obtained and experimental data on magnetoacoustic oscillations, radiofrequency size effect, de Haas–van Alphen effect, Doppler-shifted cyclotron resonance, Sondheimer effect, and the anomalous skin effect. The nature of some cyclotron resonances, observed experimentally, could be established by using the calculated values of λep = 0.19 for the electron-phonon interaction constant.
Kinetic spin-wave instability at 4.2°K
Authors: Krutsenko I. V. , Lavrinenko A. V. , Melkov G. A.
Published: December 2024

The kinetic spin-wave instability in single-crystalline spheres of yttrium iron garnet at a temperature 4.2°K is observed and studied experimentally. It is established that as the temperature of the ferrite decreases, the threshold supercritical pumping required to excite this instability increases, and the region of constant magnetic fields in which it exists decreases. The nonlinear characteristics of the kinetic instability are practically independent of the temperature of the ferrite.