bluuebunny/crossref_metadata_2025 huggingface dataset:
Weakly viscous two-dimensional incompressible fluid flows using efficient isogeometric finite element method
Authors: Mandal Mrityunjoy , Shaikh Jahangir Hossain
Published: October 2023

This paper presents a straightforward and efficient numerical simulation method for solving the Navier–Stokes equations for weakly viscous incompressible fluids describing steady flow. Our approach utilizes isogeometric finite elements to handle higher-order partial differential operators associated with weakly viscous incompressible flow problems. Specifically, our numerical formulation employs a principle of virtual power (PVP)-based weak formulation that utilizes a stream-function field, which distinguishes it from the more commonly used bi-harmonic type formulations. The usage of a stream-function field ensures a pointwise divergence-free velocity condition, making the present method suitable for low to moderately high Reynolds number flow problems. In contrast to the bi-harmonic formulation, which is typically used for describing internal flow and requires special treatment of outflow boundary conditions, the PVP-based formulation is more general and does not require special treatment at the outflow boundary. It is also demonstrated that both bi-harmonic and PVP-based weak formulations yield identical results for internal flow problems. Our method employs non-uniform rational B-spline basis functions, and we present a simple stitching technique for imposing no-slip Dirichlet boundary conditions. Finally, we solve Poisson's equation to recover the pressure field. Furthermore, we use an appropriate Gaussian quadrature that is exact for splines to speed up the computation of various element matrices, especially for high polynomial degrees. The proposed formulation is evaluated by solving a set of numerical problems, including internal flow and channel flow problems.
Fabrication of highly oriented Mn4N/Pt epitaxial bilayer structure on MgO(001) for spintronics applications
Authors: Yasuda Tomohiro , Horiuchi Takumi , Suemasu Takashi
Published: October 2023

Magnetization control by electric current or spin current is an attractive technology with potential applications in memory and logic devices, and Mn4N has attracted much attention in recent years as a candidate material for current-induced magnetization switching and magnetic domain wall motion, as well as a skyrmion material. For these applications, a bilayer structure of Mn4N and heavy metals must be formed with high crystalline quality. In this study, we have achieved the epitaxial growth of Mn4N thin films on MgO(001) with a Pt underlayer. The reflection high-energy electron diffraction images and x-ray diffraction ω-rocking curves show that the Mn4N films fabricated on the Pt underlayers exhibit higher crystalline quality than the Mn4N films directly formed on the MgO. Furthermore, anomalous Hall effect loops with bump-like structures were observed. This is considered to be due to the topological spin texture. The Mn4N/Pt epitaxial bilayer structure has potential for use in spin–orbit torque applications and is a candidate configuration for topological spin textures.
Alpha particle detection based on a NiO/β-Ga2O3 heterojunction diode
Authors: Zhou Leidang , Chen Hao , Deng Yuxin , Zhang Silong , Chen Liang , Lu Xing , Ouyang Xiaoping
Published: October 2023

Alpha particle detection has been achieved using a NiO/β-Ga2O3 heterojunction diode (HJD) detector, demonstrating the great potential of β-Ga2O3 devices for ionizing particle detection. Featuring a large area (700 × 700 μm2) and a low reverse leakage current (10−10 A), the HJD detector exhibited apparent energy spectra of 239Pu-generated alpha particles with an energy of 5.155 MeV at various bias voltages from −20 to −150 V. The peak energy of the energy spectra increased with the bias voltages. In contrast, the full width at half-maximum of the spectra was almost unchanged at high bias voltages, leading to an increased energy resolution with the increase in the bias voltages. The detector's charge collection efficiency (CCE) and energy resolution reached 14.82% and 17.54% at −150 V, respectively. The compromised CCE and energy resolution were revealed to be limited by the insufficient depletion width of the NiO/β-Ga2O3 HJD.
Experimental investigation of three-dimensional free-surface and interfacial sloshing in a vertical cylindrical tank
Authors: Liu Dongxi , Lu Tianze
Published: October 2023

In the present study, hundreds of experiments have been conducted on the three-dimensional free-surface and interfacial sloshing in a vertical cylindrical tank containing two immiscible liquids. The bounds of different free-surface and interfacial wave regimes are determined by maintaining fixed excitation amplitude and slowly increasing excitation frequency until another type of wave regime began to appear. In general, three types of the free-surface wave regimes are observed when the excitation frequency is in the neighborhood of the lowest natural frequency of the free surface, i.e., planar gravity wave, chaotic gravity wave, and swirling gravity wave. Similarly, when the excitation frequency is near the lowest natural frequency of the internal interface, three types of interfacial wave regimes, i.e., planar gravity wave, chaotic gravity-capillary wave, and swirling gravity-capillary wave, are generated. Besides, it is worth pointing out that when the excitation frequency is near the lowest natural frequency of the internal interface as well as very close to a third of the lowest natural frequency of the free surface, large-amplitude rotating wave motion occurs at both the free surface and the internal interface. This is due to even though the excitation frequency is far away from the natural frequency of the free surface, the secondary resonance can still become dominant and lead to large-amplitude motion of the free-surface rotating wave and subsequently influences the internal interface. This paper reveals that the sloshing behaviors of two-layer liquid in the vertical cylindrical tank are much more complicated than those of single-layer liquid.
Enhanced boiling heat transfer using conducting–insulating microcavity surfaces in an electric field: A lattice Boltzmann study
Authors: Cai Fanming , Liu Zhaomiao , Zheng Nan , Pang Yan
Published: October 2023

The field trap effect on the microcavity surface under the action of an electric field is not conducive to boiling heat transfer. This numerical study found that using conducting–insulating microcavity surfaces in an electric field removes the field trap effect, increasing the critical heat flux by more than 200%. Bubble behavior and heat transfer mechanisms on heating surfaces were further explored. The results show that a large electrical force can be generated at the junction of the conducting and insulating surfaces under the action of the electric field, which drives the bubbles in the cavity to departure quickly from the heating surface and avoids the formation of a vapor block. As the electric field intensity increases, the contact line produces pinning, which facilitates the formation of multiple continuously open vapor–liquid separation paths on the heating surface, resulting in a significant enhancement of the boiling heat transfer performance. Finally, a modified correlation equation is proposed to predict the critical heat flux under non-uniform electric field.
Hydrodynamic energy collection using a cylinder with different cross sections based on macro-fiber composite
Authors: Shen Yu , Wang Jiasong , Zheng Hanxu , Sun Yuankun
Published: October 2023

With the rapid development of small and microelectronic devices, energy utilization from the surrounding environment has been paid significant attention. This study aims to enhance the performance of energy harvesting devices utilizing a macro-fiber composite (MFC) attached to a cantilever beam with a cylinder attached at the free end with three different cross sections, namely circular, square, and triangular. Experiments were conducted in a low-speed circulating water flume at Reynolds numbers ranging within 770–8800. Three oscillation modes based on different cross sections can be observed: (1) vortex-induced vibration (VIV) for the circular cylinder water energy harvester (CWEH); (2) combined VIV-galloping for the triangular cylinder water energy harvester (TWEH); and (3) separated weak vortex-induced vibration-galloping for the square cylinder water energy harvester. The characteristics of the MFC water energy harvester are revealed through the vibration mechanism analysis. The effects of flow velocity, resistance, and cross section on the energy harvester were studied, and the flow field was analyzed. The energy harvesting results indicate that the TWEH exhibits the highest voltage, power, power density, and efficiency among the three devices; the maximum voltage, power, power density, and efficiency achieved are 28.9 V, 241.1 μW, 512.6 μW/cm3, and 0.23%, respectively. Despite the TWEH exhibiting a maximum efficiency that is 0.68 times that of the CWEH, it is noteworthy that the TWEH presents a superior performance in terms of maximum voltage, power, and power density by factors of 2.77, 7.37, and 7.38, respectively, compared to the CWEH. Hence, the research suggests that the TWEH is the most suitable device for energy collection under low-speed water flow conditions.
Large exchange bias effect and complex magnetism in a tetragonal high entropy spinel oxide
Authors: Sharma Neha , Jangid Sonika , Choudhury Sambit , Mahatha Sanjoy Kr , Singh Ravi P. , Marik Sourav
Published: October 2023

In this study, we have employed a high entropy approach to synthesize a hitherto unexplored tetragonal high entropy spinel with composition (Mn0.2Co0.2Ni0.2Cu0.2Zn0.2)Mn1.8Cr0.2O4. The temperature and field-dependent magnetization studies reveal a complex magnetic behavior characterized by a ferrimagnetic transition occurring at (TC) 85 K, followed by a noncollinear magnetic ground state below 23 K. Remarkably, we have observed the appearance of a large exchange bias effect (exchange bias field HEB = 7.6 kOe at 4 K) below the TC = 85 K in the field cooled mode. The uncompensated magnetic moments in this disordered system create unidirectional anisotropy, leading to the exchange bias effect. The appearance of the large exchange bias effect in a complex high entropy oxide (HEO) indicates that disordered ferrimagnetic HEOs are a promising class to explore systems having potential applications in spintronics.
Diamond quantum sensors in microfluidics technology
Authors: Fujiwara Masazumi
Published: October 2023

Diamond quantum sensing is an emerging technology for probing multiple physico-chemical parameters in the nano- to micro-scale dimensions within diverse chemical and biological contexts. Integrating these sensors into microfluidic devices enables the precise quantification and analysis of small sample volumes in microscale channels. In this Perspective, we present recent advancements in the integration of diamond quantum sensors with microfluidic devices and explore their prospects with a focus on forthcoming technological developments.
Statistical inference of the inverted exponentiated Lomax distribution using generalized order statistics with application to COVID-19
Authors: Nassr Said G. , Hassan Amal S. , Almetwally Ehab M. , Al Mutairi Aned , Khashab Rana H. , ElHaroun Neema M.
Published: October 2023

In this study, the parameters of the inverted exponentiated Lomax distribution via generalized order statistics are assessed using Bayesian and maximum likelihood approaches. The maximum likelihood estimators along with approximate confidence intervals are calculated. Under the squared error loss function, the Bayesian estimator, percentile bootstrap, and bootstrap-t credible periods are produced. Furthermore, the proposed estimators are dedicated to schemes such as type-II censored ordinary order statistics joint density function. A numerical simulation is used to assess the behavior and sensitivity of the estimates for various sample sizes. From the posterior distributions, the Metropolis–Hastings technique is used to generate Markov chain Monte Carlo samples. We utilize this technique to examine a current dataset of interest: daily cases of COVID-19 instances detected in Saudi Arabia from May 31 to October 28, 2020 (inclusive). In the future, the proposed methodology could be useful for analyzing data on COVID-19 instances in other countries for comparative studies.
Worsening psychological wellbeing of Australian hospital clinical staff during three waves of the coronavirus (COVID-19) pandemic
Authors: Holton Sara , Rasmussen Bodil , Crowe Shane , Trueman Melody , Dabscheck Adrian , Booth Sarah , Hitch Danielle , Said Catherine M. , Haines Kimberley J. , Wynter Karen
Published: October 2023

Objective This study aimed to assess and compare the psychological wellbeing of Australian hospital clinical staff at three timepoints during the coronavirus disease 2019 (COVID-19) pandemic. Methods An anonymous, online, cross-sectional survey was conducted at three timepoints during the COVID-19 pandemic (T1: May–June 2020; T2: October–December 2020; T3: November 2021–January 2022). The surveys were completed by nurses, midwives, doctors and allied health staff employed at a large metropolitan tertiary health service located in Melbourne, Australia. The Depression, Anxiety and Stress Scale (DASS-21) assessed respondents’ psychological wellbeing in the past week. General linear models were used to measure the effects of survey timepoint on DASS-21 subscale scores, adjusting for selected sociodemographic and health characteristics. Results A total of 1470 hospital clinical staff completed at least one survey (T1: 668 (14.7%), T2: 358 (7.9%) and T3: 444 (9.8%)). Respondents’ sociodemographic characteristics were similar across the three timepoints and within professional discipline groups. Respondents’ psychological wellbeing was worse at T3 compared to the earlier survey timepoints. Adjusting for respondent characteristics, depression, anxiety and stress scores were significantly higher for respondents of the third survey compared to the first (P < 0.001). Conclusions There was a significant and persistent negative impact on the psychological wellbeing of hospital clinical staff in Australia across waves of the COVID-19 pandemic. Hospital clinical staff would benefit from ongoing and continued wellbeing support during and after pandemic waves.
Effects of sardines as an attractant on carnivore detection and temporal activity patterns at remote camera traps
Authors: Siegfried Anna C. , Harris Stephen N. , Olfenbuttel Colleen , Jachowski David S.
Published: October 2023

Context Adding an attractant to remote camera traps has become a popular method to increase detections of cryptic carnivores. However, there is ongoing debate about whether this practice can bias the behaviour and activity patterns of these species. Aims Our aim was to determine how using a popular attractant at camera traps could affect carnivore detection probabilities and temporal activity. Methods We used an experimental design in which we randomly set half of our camera traps on arrays at two sites in western North Carolina with an attractant: canned sardines in oil. Halfway through the survey season, we switched which camera traps had sardines and which did not. We estimated detection probability for each carnivore species observed using occupancy models, and we used kernel density estimations to evaluate changes in diel activity patterns between camera traps with and without an attractant. Key results We found that when sardines were used at camera traps, detectability of bobcats (Lynx rufus), coyotes (Canis latrans), northern raccoons (Procyon lotor), Virginia opossums (Didelphis virginiana), and eastern spotted skunks (Spilogale putorius) more than doubled, but there was little or no effect on striped skunk (Mephitis mephitis) detectability. Of the species we most frequently detected (coyotes, raccoons, and opossums), activity patterns between camera traps with and without a sardine attractant overlapped moderately to highly, and a significant effect on diel activity patterns was observed only for raccoons. Conclusions Use of attractants can greatly increase the probability of detecting nearly all carnivores at camera traps. The effects of attractants on diel activity patterns are species-specific, with two of our three most-detected species unaffected by their use, suggesting that attractants can be used to effectively study these behaviours in some carnivore species. Implications A sardine attractant can increase the detection of many carnivore species, using camera traps, without causing a significant deviation of diel activity patterns, thus allowing for unbiased investigations into most species’ spatio–temporal behaviour in the Appalachian Mountains – and likely other systems.
Mining in space could spur sustainable growth
Authors: Fleming Maxwell , Lange Ian , Shojaeinia Sayeh , Stuermer Martin
Published: October 2023

Growth models with resources and environmental externalities typically assume that planet Earth is a closed economy. However, private firms like Blue Origin and SpaceX have reduced the cost of rocket launches by a factor of 20 over the last decade. What if these costs continue to decline, making mining from asteroids or the moon feasible? What would be the implications for economic growth and the environment? This paper provides stylized facts about cost trends, geology, and the environmental impact of mining on Earth and potentially in Space. We extend a neoclassical growth model to investigate the transition from mining on Earth to Space. We find that such a transition could potentially allow for continued growth of metal use, while limiting environmental and social costs on Earth. Acknowledging the high uncertainty around the topic, our paper provides a starting point for research on how Space mining could contribute to sustainable growth on Earth.
Viral nanoparticle vaccines against S100A9 reduce lung tumor seeding and metastasis
Authors: Chung Young Hun , Ortega-Rivera Oscar A. , Volckaert Britney A. , Jung Eunkyeong , Zhao Zhongchao , Steinmetz Nicole F.
Published: October 2023

Metastatic cancer accounts for 90% of all cancer-related deaths and continues to be one of the toughest challenges in cancer treatment. A growing body of data indicates that S100A9, a major regulator of inflammation, plays a central role in cancer progression and metastasis, particularly in the lungs, where S100A9 forms a premetastatic niche. Thus, we developed a vaccine against S100A9 derived from plant viruses and virus-like particles. Using multiple tumor mouse models, we demonstrate the effectiveness of the S100A9 vaccine candidates in preventing tumor seeding within the lungs and outgrowth of metastatic disease. The elicited antibodies showed high specificity toward S100A9 without cross-reactivity toward S100A8, another member of the S100A family. When tested in metastatic mouse models of breast cancer and melanoma, the vaccines significantly reduced lung tumor nodules after intravenous challenge or postsurgical removal of the primary tumor. Mechanistically, the vaccines reduce the levels of S100A9 within the lungs and sera, thereby increasing the expression of immunostimulatory cytokines with antitumor function [(interleukin) IL-12 and interferonγ] while reducing levels of immunosuppressive cytokines (IL-10 and transforming growth factorβ). This also correlated with decreased myeloid-derived suppressor cell populations within the lungs. This work has wide-ranging impact, as S100A9 is overexpressed in multiple cancers and linked with poor prognosis in cancer patients. The data presented lay the foundation for the development of therapies and vaccines targeting S100A9 to prevent metastasis.
Interdisciplinary college curriculum and its labor market implications
Authors: Han Siqi , LaViolette Jack , Borkenhagen Chad , McAllister William , Bearman Peter S.
Published: October 2023

This article sheds light on how to capture knowledge integration dynamics in college course content, improves and enriches the definition and measurement of interdisciplinarity, and expands the scope of research on the benefits of interdisciplinarity to postcollege outcomes. We distinguish between what higher education institutions claim regarding interdisciplinarity and what they appear to actually do. We focus on the core academic element of student experience—the courses they take, develop a text-based semantic measure of interdisciplinarity in college curriculum, and test its relationship to average earnings of graduates from different types of schools of higher education. We observe that greater exposure to interdisciplinarity—especially for science majors—is associated with increased earnings after college graduation.
Public–private partnerships in fostering outer space innovations
Authors: Rausser Gordon , Choi Elliot , Bayen Alexandre
Published: October 2023

As public and private institutions recognize the role of space exploration as a catalyst for economic growth, various areas of innovation are expected to emerge as drivers of the space economy. These include space transportation, in-space manufacturing, bioproduction, in-space agriculture, nuclear launch, and propulsion systems, as well as satellite services and their maintenance. However, the current nature of space as an open-access resource and global commons presents a systemic risk for exuberant competition for space goods and services, which may result in a “tragedy of the commons” dilemma. In the race among countries to capture the value of space exploration, NASA, American research universities, and private companies can avoid any coordination failures by collaborating in a public–private research and development partnership (PPRDP) structure. We present such a structure founded upon the principles of polycentric autonomous governance, which incorporate a decentralized autonomous organization framework and specialized research clusters. By advancing an alignment of incentives among the specified participatory members, PPRDPs can play a pivotal role in stimulating open-source research by creating positive knowledge spillover effects and agglomeration externalities as well as embracing the nonlinear decomposition paradigm that may blur the distinction between basic and applied research.
Investing in mini-livestock production for food security and carbon neutrality in China
Authors: Bai Zhaohai , Wu Xiaofei , Lassaletta Luis , Haverkamp Alexander , Li Wei , Yuan Zengwei , Aguilera Eduardo , Uwizeye Aimable , Sanz-Cobena Alberto , Zhang Nannan , Fan Xiangwen , Zhu Feng , Dicke Marcel , Wang Xuan , Ma Lin
Published: October 2023

Future food farming technology faces challenges that must integrate the core goal of keeping the global temperature increase within 1.5 °C without reducing food security and nutrition. Here, we show that boosting the production of insects and earthworms based on food waste and livestock manure to provide food and feed in China will greatly contribute to meeting the country’s food security and carbon neutrality pledges. By substituting domestic products with mini-livestock (defined as earthworms and insects produced for food or feed) protein and utilizing the recovered land for bioenergy production plus carbon capture and storage, China’s agricultural sector could become carbon-neutral and reduce feed protein imports to near zero. This structural change may lead to reducing greenhouse gas emissions by 2,350 Tg CO
2
eq per year globally when both domestic and imported products are substituted. Overall, the success of mini-livestock protein production in achieving carbon neutrality and food security for China and its major trading partners depends on how the substitution strategies will be implemented and how the recovered agricultural land will be managed, e.g., free use for afforestation and bioenergy or by restricting this land to food crop use. Using China as an example, this study also demonstrates the potential of mini-livestock for decreasing the environmental burden of food production in general.
Molecular mechanisms controlling the biogenesis of the TGF-β signal Vg1
Authors: Dingal P. C. Dave P. , Carte Adam N. , Montague Tessa G. , Lim Suan Medel B. , Schier Alexander F.
Published: October 2023

The TGF-beta signals Vg1 (Dvr1/Gdf3) and Nodal form heterodimers to induce vertebrate mesendoderm. The Vg1 proprotein is a monomer retained in the endoplasmic reticulum (ER) and is processed and secreted upon heterodimerization with Nodal, but the mechanisms underlying Vg1 biogenesis are largely elusive. Here, we clarify the mechanisms underlying Vg1 retention, processing, secretion, and signaling and introduce a Synthetic Processing (SynPro) system that enables the programmed cleavage of ER-resident and extracellular proteins. First, we find that Vg1 can be processed by intra- or extracellular proteases. Second, Vg1 can be processed without Nodal but requires Nodal for secretion and signaling. Third, Vg1-Nodal signaling activity requires Vg1 processing, whereas Nodal can remain unprocessed. Fourth, Vg1 employs exposed cysteines, glycosylated asparagines, and BiP chaperone-binding motifs for monomer retention in the ER. These observations suggest two mechanisms for rapid mesendoderm induction: Chaperone-binding motifs help store Vg1 as an inactive but ready-to-heterodimerize monomer in the ER, and the flexibility of Vg1 processing location allows efficient generation of active heterodimers both intra- and extracellularly. These results establish SynPro as an in vivo processing system and define molecular mechanisms and motifs that facilitate the generation of active TGF-beta heterodimers.
In vitro DNA repair genomics using XR-seq withEscherichia coliand mammalian cell-free extracts
Authors: Cao Xuemei , Kose Cansu , Selby Christopher P. , Sancar Aziz
Published: October 2023

The XR-seq (eXcision Repair-sequencing) method has been extensively used to map nucleotide excision repair genome-wide in organisms ranging fromEscherichia colito yeast,Drosophila, Arabidopsis, mice, and humans. The basic feature of the method is to capture the excised oligomers carrying DNA damage, sequence them, and align their sequences to the genome. We wished to perform XR-seq in vitro with cell-free extract supplemented with a damaged DNA substrate so as to have greater flexibility in investigating factors that affect nucleotide excision repair in the cellular context [M. J. Smerdon, J. J. Wyrick, S. Delaney,J. Biol. Chem.299, 105118 (2023)]. We report here the successful use of ultraviolet light-irradiated plasmids as substrates for repair in vitro and in vivo byE. coliandE. colicell-free extracts and by mammalian cell-free extract. XR-seq analyses demonstrated common excision product length and sequence characteristics in vitro and in vivo for both the bacterial and mammalian systems. This approach is expected to help understand the effects of epigenetics and other cellular factors and conditions on DNA repair.
What can attitudes reveal about prejudices?
Authors: Hinner Michael B.
Published: October 2023

The chapter takes a conceptual approach to prejudices in that it
reviews and applies the relevant research and literature on the subject and
related issues. That is why it first examines the interrelationship of
ethnocentrism, stereotypes, and prejudices in order to show how and why
prejudices arise. It becomes clear from this discussion that the social
environment can have an important and early impact on a person’s
predisposition. Another aspect to consider is identity because a person’s
self-image and self-esteem can determine whether a person is more
susceptible to prejudices or not. Next, the paper examines attitutes and
persusion to explain how prejudices can be overcome. Here as well, it
becomes clear why some individuals are swayed by messages designed to
overcome prejudices and others are not. Taking these factors into
consideration, the paper ends with a brief description of what measures need
to be undertaken in oder to overcome prejudices.
Resistive switching behaviour of nickel nanoparticle-embedded naphthalene sulphonic acid-doped polyaniline nanocomposites
Authors: Bhaumik Madhumita , Maity Arjun , Brink Hendrik G , Dlamini Zolile Wiseman , Vallabhapurapu SrinivasuVijaya
Published: October 2023

Hybrid nanocomposite (NC) materials comprising organic polymers and inorganic metal nanoparticles (NPs) with unique properties are popular for their advanced technological applications including resistive switching memory devices. Herein, NCs of 2-naphthalene sulphonic acid-doped polyaniline nanotubes (PANI-NSA NTs) and nickel nanoparticles (Ni NPs) were synthesized via a facile chemical synthesis procedure where metallic Ni NPs were embedded in/deposited onto the surface of PANI-NSA NTs by a simple reduction method. Different characterization methods revealed successful deposition of weak ferromagnetic Ni NPs onto the PANI-NSA matrix. The bipolar resistive switching behaviour of the as-synthesized PANI-NSA + Ni NCs was investigated under the application of voltage stress in a two-terminal sandwiched device configuration. The fabricated indium tin oxide/PANI-NSA + Ni/silver (ITO/PANI-NSA + Ni/Ag) device displays bipolar resistive switching properties having a memory window of ∼1.5 × 103, and switches effectively over 200 cycles. Ohmic conduction in the lower-voltage regime and the space-charge-limited Mott–Gurney current conduction model in the higher-voltage region were identified as major charge conduction mechanisms in the high resistive state of the device. On the other hand, in the entire low resistive state region the experimental data followed the Mott–Gurney conduction model.
Perspectives of the generation and measurement of small electric currents
Authors: Kaneko Nobu-Hisa , Tanaka Takahiro , Okazaki Yuma
Published: October 2023

This paper provides a comprehensive overview of the historical background, current status, and future prospects related to the generation and measurement of small electric currents. It specifically caters to nonprofessional readers, with the aim of making the information comprehensible. A range of technologies are introduced, applicable in both basic research and industrial context. Quantum-mechanical approaches have been the focus of extensive efforts in this field, encompassing various types of single-electron pumps and combinations of two other quantum standards: the Josephson voltage standard and the quantized Hall resistance standard. These methods offer a reliable and precise means of generating and measuring small electric currents, minimizing uncertainties. However, operating complex cryogenic systems requires specialized expertise. Alternatively, conventional room-temperature systems are comparatively easier to handle. They employ low-noise amplifiers in conjunction with stable high-value resistors or capacitors charged with voltage ramps. This paper not only examines the characteristics of the both quantum and classical approaches from multiple perspectives but also outlines current and future applications for the generation and measurement of small electric currents.
Influence of the reference surface and AFM tip on the radius and roundness measurement of micro spheres
Authors: Oertel Erik , Manske Eberhard
Published: October 2023

The performance of tactile and optical surface sensors for nano and micro coordinate measuring machines is currently limited by the lack of precisely characterised micro spheres, since established strategies have mainly been developed for spheres in the range of millimetres or above. We have, therefore, recently focused our research efforts towards a novel strategy for the characterisation of spheres in the sub-millimetre range. It is based on a set of atomic force microscope (AFM) surface scans in conjunction with a stitching algorithm. To obtain an uncertainty statement, the uncertainty about the shape of the reference surface needs to be propagated via the shape of the AFM tip to the actual measurement object. However, the sampling process of an AFM is non-linear and the processing of AFM scans requires complex algorithms. We have, therefore, recently begun to model the characterisation of micro spheres through simulations. In this contribution, this model is extended by the influence of the tip and reference surface. The influence of the tip’s shape and reference surface is investigated through virtual and real experiments. The shape of the tip is varied by using tips with mean radii of 200 nm and 2 μm while sampling the same ruby sphere with a mean radius of 150 μm. In general, the simulation results imply that an uncertainty of less then 10 nm is achievable. However, an experimental validation of the model is still pending. The experimental investigations were limited by the lack of a suitable cleaning strategy for micro parts, which demonstrates the need for further investigations in this area. Although the characterisation of a full sphere has already been demonstrated, the investigations in this contribution are limited to equator measurements.
Bipartite dielectric Huygens’ metasurface for anomalous refraction
Authors: Sharma Abhishek , Wong Alex M H
Published: October 2023

Huygens’ metasurfaces—fundamentally based on Schelkunoff's equivalence principle, Huygens’ metasurfaces consist of a two-dimensional array of Huygens’ sources formed by co-located orthogonal electric and magnetic dipoles. Such metasurfaces provide electric and magnetic responses to an incoming electromagnetic (EM) wave, leading to unidirectional scattering and 2π phase coverage. We herein report a near-reflectionless coarsely discretized dielectric Huygens’ metasurface that performs anomalous refraction, offering a low-loss platform for wave manipulation at high frequencies as compared to their lossy metallic analogue. The coarse discretization dramatically simplifies the design, resulting in a metasurface that is highly efficient, cost-effective and robust. In this paper, the proposed metasurface comprises two meta-atoms per period, and is hence named the bipartite dielectric Huygens’ metasurface. Through full-wave simulations at 28 GHz, we show that the proposed metasurface can reroute an incident EM wave from θ

i
= 15° to θ

t
= − 44.5° with a very high efficiency: 87% of the scattered power is anomalously transmitted to θ

t
. Based on our observations, a coarsely discretized dielectric Huygens’ metasurface platform can be efficacious to design meta-devices with multifaceted functionalities in different frequency regimes.
2D-smoothing of laser beam fluctuations in optical compressor
Authors: Khazanov Efim
Published: October 2023

We propose a modification of the four diffraction gratings Treacy compressor (TC)—a double-smoothing grating compressor (DSGC)—which enables smoothing of spatial fluctuations of a laser beam in two directions. Smoothing along the groves is due to oblique incidence on the gratings or tilted grooves. Smoothing in the direction normal to the grooves is achieved due to the use of nonidentical pairs of gratings. It is shown that the far-field fluence and the focal beam intensity after the DSGC are like those after the TC. Smoothing is a consequence of spatial harmonics lagging behind or overtaking the main pulse in proportion to the transverse wave vector. Analytical expressions are obtained for the spectrum of fluence fluctuations and fluence rms at the DSGC output. The efficiency of suppressing small-scale self-focusing in transmissive optical elements after the DSGC, for example, in the case of post-pulse compression is assessed.
From monkeys to humans: observation-based EMG brain–computer interface decoders for humans with paralysis
Authors: Rizzoglio Fabio , Altan Ege , Ma Xuan , Bodkin Kevin L , Dekleva Brian M , Solla Sara A , Kennedy Ann , Miller Lee E
Published: October 2023

Objective. Intracortical brain–computer interfaces (iBCIs) aim to enable individuals with paralysis to control the movement of virtual limbs and robotic arms. Because patients’ paralysis prevents training a direct neural activity to limb movement decoder, most iBCIs rely on ‘observation-based’ decoding in which the patient watches a moving cursor while mentally envisioning making the movement. However, this reliance on observed target motion for decoder development precludes its application to the prediction of unobservable motor output like muscle activity. Here, we ask whether recordings of muscle activity from a surrogate individual performing the same movement as the iBCI patient can be used as target for an iBCI decoder. Approach. We test two possible approaches, each using data from a human iBCI user and a monkey, both performing similar motor actions. In one approach, we trained a decoder to predict the electromyographic (EMG) activity of a monkey from neural signals recorded from a human. We then contrast this to a second approach, based on the hypothesis that the low-dimensional ‘latent’ neural representations of motor behavior, known to be preserved across time for a given behavior, might also be preserved across individuals. We ‘transferred’ an EMG decoder trained solely on monkey data to the human iBCI user after using Canonical Correlation Analysis to align the human latent signals to those of the monkey. Main results. We found that both direct and transfer decoding approaches allowed accurate EMG predictions between two monkeys and from a monkey to a human. Significance. Our findings suggest that these latent representations of behavior are consistent across animals and even primate species. These methods are an important initial step in the development of iBCI decoders that generate EMG predictions that could serve as signals for a biomimetic decoder controlling motion and impedance of a prosthetic arm, or even muscle force directly through functional electrical stimulation.
Development of dual-path multi-pass Thomson scattering system in GAMMA 10/PDX
Authors: Yoshikawa M. , Kohagura J. , Shima Y. , Nakashima Y. , Ezumi N. , Minami R. , Yasuhara R. , Yamada I. , Funaba H. , Kenmochi N. , Minami T. , van der Meiden H. , Sakamoto M.
Published: October 2023

A dual-path Thomson scattering (DPTS) system was developed to measure electron temperature and density in a GAMMA 10/PDX central cell (CC) and an end cell (EC). The DPTS comprises CC Thomson scattering system (CC-TS) and an EC Thomson scattering system (EC-TS). In the CC-TS, we developed a multipass system to improve the signal intensities and time resolution. In the EC-TS, a double-pass system was developed as a preliminary step in developing a multipass system. In a previous EC-TS, the optical components for the double-pass configuration were placed in a vacuum vessel. To reduce the influence of stray light and facilitate alignment, a hole for the double-pass laser path was made on the partition wall in the vacuum chamber such that the probe laser could be extracted into the atmosphere and the double-path configuration could be easily adjusted. We applied DPTS to detached plasma experiments and successfully measured the core and edge electron temperatures and densities with the detached plasma experiments with the additional application of supersonic molecular beam injection and central electron cyclotron heating in the core plasma to simultaneously introduce intermittent particle flux.
Development of a dual HCN laser interferometer on a small tokamak device
Authors: Zhang N. , Liu H.Q. , Xie J.X. , Wei X.C. , Jie Y.X. , Yao Y. , Yao D.M.
Published: October 2023

A dual hydrogen cyanide (HCN) laser interferometer system was designed and developed to measure the electron density of plasma with high temporal resolution. The system comprises two terahertz continuous wave (CW) discharge-pumped HCN lasers, each emitting at a frequency of 0.89 THz and with an output power of up to 100 mW. The intermediate frequency (IF) signal is obtained by adjusting the length of the resonant cavity. The temporal resolution of the interferometer can reach 1 μs when the intermediate frequency is at 1 MHz. The feasibility of the dual HCN laser interferometer system was verified by simulating the plasma using a wedge. Preliminary experimental results were obtained on a small tokamak device, a root mean square error of the dual HCN laser interferometer is approximately 1.5×1017 m-3 when the line-integrated electron density obtained by the dual HCN laser interferometer is about 1.5×1019 m-3.
Histomorphometric evaluation, SEM, and synchrotron analysis of the biological response of biodegradable and ceramic hydroxyapatite-based grafts: from the synthesis to the bed application
Authors: Gasperini Flávio Marcos , Fernandes Gustavo Vicentis Oliveira , Mitri Fabio Franceschini , Calasans-Maia Mônica Diuana , Mavropoulos Elena , Malta Rossi Alexandre , Granjeiro José Mauro
Published: October 2023

This study aimed to analyze the physicochemical and histological properties of nanostructured hydroxyapatite and alginate composites produced at different temperatures with and without sintering and implanted in rabbit tibiae. Hydroxyapatite-alginate (HA) microspheres (425–600 µm) produced at 90 and 5 °C without (HA90 and HA5) or with sintering at 1000 °C (HA90S and HA5S) were characterized and applied to evaluate the in vitro degradation; also were implanted in bone defects on rabbit’s tibiae (n = 12). The animals were randomly divided into five groups (blood clot, HA90S, HA5S, HA90, and HA5) and euthanized after 7 and 28 d. X-ray diffraction and Fourier-transform infrared analysis of the non-sintered biomaterials showed a lower crystallinity than sintered materials, being more degradable in vitro and in vivo. However, the sinterization of HA5 led to the apatite phase’s decomposition into tricalcium phosphate. Histomorphometric analysis showed the highest (p < 0.01) bone density in the blood clot group, similar bone levels among HA90S, HA90, and HA5, and significantly less bone in the HA5S. HA90 and HA5 groups presented higher degradation and homogeneous distribution of the new bone formation onto the surface of biomaterial fragments, compared to HA90S, presenting bone only around intact microspheres (p < 0.01). The elemental distribution (scanning electron microscope and energy dispersive spectroscopy and μXRF-SR analysis) of Ca, P, and Zn in the newly formed bone is similar to the cortical bone, indicating bone maturity at 28 d. The synthesized biomaterials are biocompatible and osteoconductive. The heat treatment directly influenced the material’s behavior, where non-sintered HA90 and HA5 showed higher degradation, allowing a better distribution of the new bone onto the surface of the biomaterial fragments compared to HA90S presenting the same level of new bone, but only on the surface of the intact microspheres, potentially reducing the bone-biomaterial interface.
Transport and localization properties of excitations in one-dimensional lattices with diagonal disordered mosaic modulations
Authors: Nguyen Ba Phi , Kim Kihong
Published: October 2023

We present a numerical study of the transport and localization properties of excitations in one-dimensional lattices with diagonal disordered mosaic modulations. The model is characterized by the modulation period κ and the disorder strength W. We calculate the disorder averages

⟨
T
⟩

,

〈
ln
T
〉

, and

⟨
P
⟩

, where T is the transmittance and P is the participation ratio, as a function of energy E and system size L, for different values of κ and W. For excitations at quasiresonance energies determined by κ, we find power-law scaling behaviors of the form

⟨
T
⟩
∝

L

−

γ

a

,

⟨
ln
T
⟩
≈
−

γ
g

ln
L

, and

⟨
P
⟩
∝

L

β

, as L increases to a large value. In the strong disorder limit, the exponents are seen to saturate at the values

γ
a

∼
0.5

,

γ
g

∼
1

, and

β
∼
0.3

, regardless of the quasiresonance energy value. This behavior is in contrast to the exponential localization behavior occurring at all other energies. The appearance of sharp peaks in the participation ratio spectrum at quasiresonance energies provides additional evidence for the existence of an anomalous power-law localization phenomenon. The corresponding eigenstates demonstrate multifractal behavior and exhibit unique node structures. In addition, we investigate the time-dependent wave packet dynamics and calculate the mean square displacement

⟨

m
2

(
t
)
⟩

, spatial probability distribution, participation number, and return probability. When the wave packet’s initial momentum satisfies the quasiresonance condition, we observe a subdiffusive spreading of the wave packet, characterized by

⟨

m
2

(
t
)
⟩
∝

t

η

where η is always less than 1. We also note the occurrence of partial localization at quasiresonance energies, as indicated by the saturation of the participation number and a nonzero value for the return probability at long times.
Effect of strain rate on glass fiber reinforced polymer composite using split hopkinson pressure bar
Authors: Basrani Jitendra , Kumar Manoj , Kumar Pramod
Published: October 2023

The aim of this study is to examine the stress–strain behavior of Glass Fibre Reinforced Polymer (GFRP) composite with three different orientations, namely [0°/90°]s, [±45]s, [0°/+45°/−45°/90°]T. To achieve this, the GFRP was simulated using the Split Hopkinson Bar (SHPB) setup in ABAQUS/CAE. The striker bar was used at three different velocities (9.7 m s−1, 12.7 m s−1, and 14.3 m s−1) to produce strain rates ranging from 1000 s−1to 2000 s−1. The dynamic response of the GFRP composite was studied by considering its stress–strain behavior. The effect of strain rate on the elastic modulus and energy absorption capacity of GFRP laminates was analyzed through complete stress versus strain curves. The results showed that the elastic modulus and energy absorption capacity of GFRP laminates were sensitive to strain rates, with an increase in strain rate leading to an increase in the elastic modulus and energy absorption capacity.
Computational modeling of the thermal effects of flow on radio frequency-induced heating of peripheral vascular stents during MRI
Authors: Gross David C , Scandling Benjamin W , Leewood Alan R , Simonetti Orlando P
Published: October 2023

Purpose. The goal of this study was to develop and validate a computational model that can accurately predict the influence of flow on the temperature rise near a peripheral vascular stent during magnetic resonance imaging (MRI). Methods. Computational modeling and simulation of radio frequency (RF) induced heating of a vascular stent during MRI at 3.0 T was developed and validated with flow phantom experiments. The maximum temperature rise of the stent was measured as a function of physiologically relevant flow rates. Results. A significant difference was not identified between the experiment and simulation (P > 0.05). The temperature rise of the stent during MRI was over 10 °C without flow, and was reduced by 5 °C with a flow rate of only 58 ml min−1, corresponding to a reduction of CEM43 from 45 min to less than 1 min. Conclusion. The computer model developed in this study was validated with experimental measurements, and accurately predicted the influence of flow on the RF-induced temperature rise of a vascular stent during MRI. Furthermore, the results of this study demonstrate that relatively low flow rates significantly reduce the temperature rise of a stent and the surrounding medium during RF-induced heating under typical scanning power and physiologically relevant conditions.