bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of neural networks to synchro-Compton blazar emission models
Authors: Tzavellas A. , Vasilopoulos G. , Petropoulou M. , Mastichiadis A. , Stathopoulos S. I.
Published: January 2024

Context. Jets from supermassive black holes at the centers of active galaxies are the most powerful and persistent sources of electromagnetic radiation in the Universe. To infer the physical conditions in the otherwise out-of-reach regions of extragalactic jets, we usually rely on fitting their spectral energy distributions (SEDs). The calculation of radiative models for the jet’s non-thermal emission usually relies on numerical solvers of coupled partial differential equations.

Aims. In this work, we use machine learning to tackle the problem of high computational complexity to significantly reduce the SED model evaluation time, which is necessary for SED fittings carried out with Bayesian inference methods.

Methods. We computed the SEDs based on the synchrotron self-Compton model for blazar emission using the radiation code ATHEvA. We used them to train neural networks (NNs) to explore whether they can replace the original code, which is computationally expensive.

Results. We find that a NN with gated recurrent unit neurons (GRUN) can effectively replace the ATHEvA leptonic code for this application, while it can be efficiently coupled with Markov chain Monte Carlo (MCMC) and nested sampling algorithms for fitting purposes. We demonstrate this approach through an application to simulated data sets, as well as a subsequent application to observational data.

Conclusions. We present a proof-of-concept application of NNs to blazar science as the first step in a list of future applications involving hadronic processes and even larger parameter spaces. We offer this tool to the community through a public repository.
Upper limit of the solar wind protons backscattering efficiency from Comet 67P/Churyumov-Gerasimenko
Authors: Canu-Blot Romain , Wieser Martin , Wieser Gabriella Stenberg
Published: January 2024

Context. Solar wind ions backscattering is a fundamental plasma-surface interaction process that may occur on all celestial bodies exposed to the solar wind and lacking a significant atmosphere or magnetosphere. Yet, observations have been limited to the regolith-covered Moon and Phobos, one of the Martian moons.

Aims. We aim to expand our knowledge of the process to include comets by investigating the backscattering of solar wind protons from the surface of comet 67P/Churyumov-Gerasimenko.

Methods. We used one of the ion spectrometers on board ESA’s Rosetta spacecraft to search for evidence of backscattered solar wind protons from the cometary surface. The signal of interest was expected to be very weak and several statistical treatments of the data were essential to eliminate any influence from background noise and instrumental effects. Due to limited knowledge of the signal location within the observed parameter space, we conducted a statistical analysis to identify the most probable conditions for detecting the signal.

Results. No significant solar wind backscattered protons were ever observed by the instrument. The statement applies to the large spectrum of observation conditions. An upper limit of the backscattered proton flux is given, as well as an upper limit of the backscattering efficiency of 9 × 10−4.

Conclusions. The surface of comet 67P/Churyumov-Gerasimenko distinguishes itself as a notably weak reflector of solar wind protons, with its backscattering efficiency, at most, as large as the lowest observed backscattering efficiency from the lunar regolith.
Theoretical Ionizing Radiation Shielding Parameters of Thulium Doped Zinc Borotellurite Glass
Authors: Rusni Nur Arina Mat , Laoding Hasnimulyati , Amat Azuraida
Published: January 2024

Ionizing radiation is considered hazardous to human health but it is very crucial for many applications such as nuclear fuel processing and medical radiography. Glass has played a huge role as a shielding material for ionizing radiation in the application that requires line of sight. Nowadays, lead glass is commonly used in industry due to its properties of high density. However, lead toxicity can give harmful effects on humans’ health and the environment. As for concrete, it takes a lot of space, blocks the line of sight and the density of concrete may reduce due to prolonged exposure to radiation. To cater these problems, this study proposed a glass composition that is thulium doped zinc borotellurite glass. Thulium is used due to its potential such as resistance to corrosion and oxidation, good ductility and does not pose any environmental threat. In this study, Phy-X and WinXCom software is used. The main goal of this research is to study the theoretical radiation shielding parameters of thulium doped zinc borotellurite glass. Based on the results, it is found that the best glass sample is the sample composition with 5% thulium oxide whereby it has the highest value for mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), atomic cross section (ACS), electronic cross section (ECS) and effective atomic number (Zeff). The best glass sample with 5% thulium oxide also yields the results of the lowest half-value layer (HVL) and mean free path (MFP). Comparing the results of Phy-X and WinXCom, it is found that the deviation between the software is less than 5%. Also, when the results for each radiation shielding parameter of 5% thulium oxide are compared with other radiation shielding materials, significant results are found where the proposed glass sample provides better shielding against gamma radiation.
Profile of The First Year Student’s Argumentation Skills on General Chemistry Courses at a Public University in West Sumatera: A Preliminary Study
Authors: Gazali Fauzana , Rahayu Sri , Munzil Munzil , Wonorahardjo Surjani
Published: January 2024

Scientific argumentation is one of the key components of habits of mind, while habits of mind are one dimension of scientific literacy that should be developed in Indonesia. However, the student’s scientific argumentation ability in learning, which has been weak lately, has become a common problem that needs to be solved immediately. The solution can be related to how to evaluate the learning process, construct the problems found in learning, and design learning that can motivate students to argue. This is a descriptive study. It aimed to find out the profile of the early scientific argumentation skills of first-year students who took general chemistry courses at one of the public colleges in West Sumatra. Research instruments consist of four open and semi-closed essay questions. Those were given to 125 chemical education students involved in this study. Data was analyzed by evaluating the students’ written argumentation, which became the research samples by following the Toulmin Argumentation Pattern (TAP), consisting of claim, data, warrant, backing, and rebuttal. The study results show that most students (97.25%) have level 0–3 argumentations skills. While only 2.25% of students have level 4 argumentation skills and 0.5% are at level 5. This means that the early argumentation skills of chemistry students are still low, and only a few students are able to emerge with a rebuttal in the scientific arguments they build. These findings are further used as the basis for designing learning strategies that can improve students’ argumentation skills during the learning process, especially in general chemistry courses, so that their habits of mind and scientific literacy will also increase.
Eco-Friendly Methods of Silica Extraction from Pyrophyllite Rocks Using Sol-Gel versus Alkali Fusion Method
Authors: Fanani Hidayatulloh Ahmat , Santoso Aman
Published: January 2024

Silica is the most abundant compound on the Earth’s surface. The content of silica can be found in agricultural waste ash and mineral rocks. Extracting silica from natural sources is advantageous due to its economic feasibility and easily obtained. Silica has a wide range of applications, such as in fertilizers, adsorbents, organic reaction catalysis, biofuels/alternative energy production, and as an antimicrobial agent. One type of rock that contains the highest amount of silica is Pyrophyllite. Recent research trends have focused on various methods and sources for silica extraction, yet extracting silica from mineral rocks presents its own challenges. Pyrophyllite rock contains a high amount of silica, but its extraction is quite difficult due to the presence of crystalline silicate mineral phases. This study aims to compare the silica extraction process on Pyrophyllite rocks from Malang using the sol-gel method versus the alkali fusion method.
Green Synthesis of MnO2 Nanoparticles with Aqueous Extract of Star Apple Leaves (Chrysophyllum cainito L.)
Authors: Jalinan Izzah Dewi , Nazriati Nazriati , Sumari Sumari
Published: January 2024

Nanomaterials are materials with a size of ≤100 nm and are important for technology in today’s digital era. MnO2 is one of the most studied metal oxides nowadays because of its abundance, low toxicity, and environmentally friendly. This material can be synthesized via redox reactions. The reagents commonly used in this reaction are typically toxic and environmentally unfriendly, such as H2SO4, HCl and HNO3. Therefore, through this research, the synthesis of MnO2 was carried out using an aqueous extract of star apple leaves. Because the aqueous extract of star apple leaves is known to contain secondary metabolites which have -OH, -C=O, and -C-N groups. These groups act as reducing and capping agents for the synthesis of MnO2 NPs. In addition, this study investigated the effect of the various synthesis methods on the formation of MnO2 NPs. Based on the results of LC-MS characterization, the aqueous extract of star apple leaves contains myricetin. Myricetin has -C=O and -OH groups which are reactive to MnO4- ions in aqueous solution, so that MnO4- is reduced to MnO4. This fact is supported by the results of the P-XRD characterization, which proves the presence of R-MnO2 and γ- MnO2 were obtained.
Theoretical study of copper corrosion prevention by terpenoid green inhibitors of thymol, carvacrol, and thymohydroquinone
Authors: Hadisaputra Saprizal , Abhi Purwoko Agus , Hakim Aliefman , Hamdiani Saprini
Published: January 2024

Electronic parameters have been used to predict the corrosion inhibition performance of the green inhibitors of thymol, carvacrol, and thymohydroquinone against copper. Molecular modeling was carried out at the density functional and ab initio levels and Monte Carlo molecular dynamics. Tymohydroquinone can prevent copper corrosion better than the other two monoterpenoids. Molecular dynamics studies show that corrosion inhibitors are adsorbed on the metal surface, thereby inhibiting corrosion from occurring on the metal surface.
Process Design of Multifeed and Multiproduct Sugar Factories
Authors: Panca Anugraha Rendra , Kurniasari Rosalia , Rosanty Amalia P.S. , Taufany Fadlilatul , Juwari Juwari , Renanto Renanto
Published: January 2024

Indonesia’s journey toward food self-sufficiency faces challenges with declining sugar production from seasonal sugarcane harvesting. To overcome this, alternative year-round and abundant sources like coconut sap and sorghum offer potential solutions. This study tackles the decreasing trend in sugar production through the optimization of a miniplant utilizing multifeed sources sugarcane, coconut sap, and sorghum to produce white crystal, brown sugar, and syrup. The objective is to ensure yearround plant operation. The process design focuses on maximizing profits, considering total sales and operational costs related to raw materials, water, and steam. Constraints are implemented to production capacities for sugarcane (15,000 kg/day), coconut sap (6,000 kg/day), and sorghum (9,000 kg/day). Maximizing the potential of alternative biomass materials involves a combined feed of coconut sap and sorghum raw material. The design process flow involves sugar production using only sugarcane feed for the first 4 months and, for the subsequent 8 months, transitioning to a combined feed of coconut sap and sorghum to create multiproduct sugar. From the design process achieved maximum profit of Rp7,096,618,000.00. This research provides valuable insights into diversifying sugar production, promoting sustainability and economic viability in Indonesian sugar industry.
Screening of Factors Influencing Keratinase Fermentation from Bacillus Haynesii BK1H using The Plackett-Burman Design (PBD)
Authors: Firli Masruroh Isna , Hendrik Sanjaya Eli , Alvionita Mieke , Suharti Suharti
Published: January 2024

Keratinase is a class of proteases that degrade keratin into polypeptides and amino acids by breaking peptide and disulfide bonds in keratinous proteins. Protease is one of the largest industrial enzymes, the global protease market is increasing rapidly every year. In previous studies, a keratinase-producing microbe was isolated from Bleduk Kuwu which was identified as Bacillus haynesii BK1H. However, further study needs to be done to optimize the production by observing microenvironmental factors that influence keratinase production. In this study, screening some microenvironmental factors is reported. Screening factors including carbon sources, type and concentration of metal ions, agitation speed, amount of inoculum, pH, and temperature. Screening for these factors was started with the One Factor at A Time (OFAT) method and followed by the Plackett-Burman Design (PBD) method. In this study, sequential work was done: (1) Regeneration of Bacillus haynesii BK1H Microbes, (2) Preparation of Tyrosine Standard Series Solutions, (3) Screening of Factors Affecting Protease Fermentation of Bacillus haynesii BK1H using the One Factor at A Time (OFAT) method. ), and (4) Maintaining Significantly Influential Factors by Using Plackett-Burman Design (PBD). The results of the OFAT approach showed that the best condition for keratinase production was achieved at rice husk concentration, additional carbon source, of 1%; pH of 7; a temperature of 35°C; the amount of inoculum of 1%; agitation speed of 150 rpm; magnesium sulfate concentration of 0.04 g/mL, and calcium chloride concentration of 0.0005 g/m. Justification of those factors using PBD confirmed that only additional rice husk, magnesium sulfate and calcium chloride concentration, and agitation speed were significantly important toward keratinase production at selected experiment level limits.
Development of A Resistive Sensor Array Based on Graphene and Conducting Polymer Composites for Coffee Aroma Classification
Authors: Mulyono Tri , Siswoyo Asnawati , Lestari Puji Bunga , Zulfikar  , Mufliha Yeni Maulidah
Published: January 2024

This work aims to create a resistive sensor array for categorizing coffee from various plantations. A mixture of graphene oxide and a conductive polymer is used to create the sensor array. Eight types of sensors were made by dripping various mixtures of graphene oxide, polypyrrole, polyaniline, and poly acetate materials on the interdigitated electrode. Coffee fragrance gas was used for the sensor array test. The surface of the sensor array receives the scent gas created by the brewing of coffee grinds. Each sensor’s response profile is recorded. Each coffee sample has a distinct sensor response profile for simple separation with a distinct pattern. PCA analysis was used to examine sensor responses in order to find classification patterns of coffee samples from diverse plantations that were separated by brewing category. Sensor response data underwent PCA analysis, yielding scores of 54.74% PC1 and 26.17% PC2. These findings suggest that graphene-based and conducting polymer sensor array have a good potential for quick differentiation of different coffee varieties.
Error estimates for finite element discretizations of the instationary Navier–Stokes equations
Authors: Vexler Boris , Wagner Jakob
Published: January 2024

In this work we consider the two dimensional instationary Navier–Stokes equations with homogeneous Dirichlet/no-slip boundary conditions. We show error estimates for the fully discrete problem, where a discontinuous Galerkin method in time and inf-sup stable finite elements in space are used. Recently, best approximation type error estimates for the Stokes problem in the L∞(I; L2(Ω)), L2(I; H1(Ω)) and L2(I; L2(Ω)) norms have been shown. The main result of the present work extends the error estimate in the L∞(I; L2(Ω)) norm to the Navier–Stokes equations, by pursuing an error splitting approach and an appropriate duality argument. In order to discuss the stability of solutions to the discrete primal and dual equations, a specially tailored discrete Gronwall lemma is presented. The techniques developed towards showing the L∞(I; L2(Ω)) error estimate, also allow us to show best approximation type error estimates in the L2(I; H1(Ω)) and L2(I; L2(Ω)) norms, which complement this work.
Agriculture numérique : une promesse au service d’un nouvel esprit du productivisme
Authors: Martin Théo , Schnebelin Éléonore
Published: January 2024

Depuis la fin des années 2010, l’agriculture numérique connaît un essor important caractérisé par la création d’entreprises, de dispositifs de recherche mais également la mise à l’agenda des politiques publiques. Nous proposons ici de comprendre l’agriculture numérique comme une promesse technoscientifique qui renouvelle l’esprit du productivisme agricole. Dans une première partie, nous identifions les régularités discursives et la singularité d’une promesse traversée par deux tensions. L’une oppose l’annonce d’une rupture technologique à l’impératif d’une légitimité qui passe par un ancrage aux structures existantes. L’autre confronte la construction rhétorique d’une agriculture numérique au singulier à la diversité des innovations et des modèles agricoles et alimentaires qu’elle intègre. Dans une seconde partie, nous analysons les réponses que cette promesse fournit aux critiques d’un productivisme en crise renouvelant ainsi l’esprit du productivisme agricole.
Assessing the moderating effect of environmental regulation on the process of media reports affecting enterprise investment inefficiency in China
Authors: Feng Yanchao , Huang Rongbing , Chen Yidong , Sui Guoshuo
Published: January 2024

To achieve the triple goals of digesting excess capacity, making effective investments, and accelerating green governance, it is important and necessary to comprehensively examine the intrinsic relationship between media reports, environmental regulation, and enterprise investment inefficiency. To this end, this study employs multiple econometric models to investigate the intrinsic relationship between them by using the data of listed companies in China’s A-share heavy-polluting industries between 2010 and 2020. The results of the study are as follows. Firstly, media reports can encourage heavy-polluting enterprises to pay attention to stakeholder demands and significantly ameliorate the enterprise investment inefficiency. In addition, environmental regulation can ameliorate the enterprise investment inefficiency through the “push-back effect” and “compensation effect”. Moreover, pollution fees can positively moderate the amelioration effect of media reports on the investment inefficiency of heavy-polluting enterprises, while it fails in terms of environmental protection subsidies. Finally, conclusions and policy implications are provided.
Dynamical behavior-based approach for the evaluation of treatment efficacy: The case of immuno-oncology
Authors: Zugaj Didier , Fenneteau Frédérique , Tremblay Pierre-Olivier , Nekka Fahima
Published: January 2024

Sophistication of mathematical models in the pharmacological context reflects the progress being made in understanding physiological, pharmacological, and disease relationships. This progress has illustrated once more the need for advanced quantitative tools able to efficiently extract information from these models. While dynamical systems theory has a long history in the analysis of systems biology models, as emphasized under the dynamical disease concept by Mackey and Glass [Science 197, 287–289 (1977)], its adoption in pharmacometrics is only at the beginning [Chae, Transl. Clin. Pharmacol. 28, 109 (2020)]. Using a quantitative systems pharmacology model of tumor immune dynamics as a case study [Kosinsky et al., J. Immunother. Cancer 6, 17 (2018)], we here adopt a dynamical systems analysis to describe, in an exhaustive way, six different statuses that refer to the response of the system to therapy, in the presence or absence of a tumor-free attractor. To evaluate the therapy success, we introduce the concept of TBA, related to the Time to enter the tumor-free Basin of Attraction, and corresponding to the earliest time at which the therapy can be stopped without jeopardizing its efficacy. TBA can determine the optimal time to stop drug administration and consequently quantify the reduction in drug exposure.
Dual delivery gene-activated scaffold directs fibroblast activity and keratinocyte epithelization
Authors: Laiva Ashang L. , O'Brien Fergal J. , Keogh Michael B.
Published: January 2024

Fibroblasts are the most abundant cell type in dermal skin and keratinocytes are the most abundant cell type in the epidermis; both play a crucial role in wound remodeling and maturation. We aim to assess the functionality of a novel dual gene activated scaffold (GAS) on human adult dermal fibroblasts (hDFs) and see how the secretome produced could affect human dermal microvascular endothelial cells (HDMVECs) and human epidermal keratinocyte (hEKs) growth and epithelization. Our GAS is a collagen chondroitin sulfate scaffold loaded with pro-angiogenic stromal derived factor (SDF-1α) and/or an anti-aging β-Klotho plasmids. hDFs were grown on GAS for two weeks and compared to gene-free scaffolds. GAS produced a significantly better healing outcome in the fibroblasts than in the gene-free scaffold group. Among the GAS groups, the dual GAS induced the most potent pro-regenerative maturation in fibroblasts with a downregulation in proliferation (twofold, p < 0.05), fibrotic remodeling regulators TGF-β1 (1.43-fold, p < 0.01) and CTGF (1.4-fold, p < 0.05), fibrotic cellular protein α-SMA (twofold, p < 0.05), and fibronectin matrix deposition (twofold, p < 0.05). The dual GAS secretome also showed enhancements of paracrine keratinocyte pro-epithelializing ability (1.3-fold, p < 0.05); basement membrane regeneration through laminin (6.4-fold, p < 0.005) and collagen IV (8.7-fold, p < 0.005) deposition. Our findings demonstrate enhanced responses in dual GAS containing hDFs by proangiogenic SDF-1α and β-Klotho anti-fibrotic rejuvenating activities. This was demonstrated by activating hDFs on dual GAS to become anti-fibrotic in nature while eliciting wound repair basement membrane proteins; enhancing a proangiogenic HDMVECs paracrine signaling and greater epithelisation of hEKs.
Energy is not a convex function of particle number for r−k interparticle potentials with k > log34
Authors: Ayers Paul W.
Published: January 2024

The energy of a many-particle system is not convex with respect to particle number for r−k interparticle repulsion potentials if k > log34 ≈ 1.262. With such potentials, some finite electronic systems have ionization potentials that are less than the electron affinity: they have negative band gap (chemical hardness). Although the energy may be a convex function of the number of electrons (for which k = 1), it suggests that finding an analytic proof of convexity will be very difficult. The bound on k is postulated to be tight. An apparent signature of non-convex behavior is that the Dyson orbital corresponding to the lowest-energy mode of electron attachment has a vanishingly small amplitude.
Higher-order clustering patterns in simplicial financial systems
Authors: Maletić Slobodan , Andjelković Miroslav
Published: January 2024

The interest in induced higher-order relational and multidimensional structures embedded in the financial complex dataset is considered within the applied algebraic topology framework. The aim is to transcend the binary correlations when the interactions of the underlying system are stored in the entries of the cross-correlation matrix. By applying different criteria, we examined aggregations of firms through higher-order clustering of the financial system. The outcome is the extraction of patterns that appear in assemblages of firms due to their multidimensional properties embedded in the cross-correlation matrices. Results are compatible with classifying firms into clusters due to the industry they belong to. Furthermore, the novel and mixed collections of firms are revealed based on the applied mathematical approach. In the broader context, results shed light on the higher-order organization of interactions embedded in the cross-correlation matrix and, as a consequence, extract patterns of collective behavior within a complex system.
The probability of epidemic burnout in the stochastic SIR model with vital dynamics
Authors: Parsons Todd L. , Bolker Benjamin M. , Dushoff Jonathan , Earn David J. D.
Published: January 2024

We present an approach to computing the probability of epidemic “burnout,” i.e., the probability that a newly emergent pathogen will go extinct after a major epidemic. Our analysis is based on the standard stochastic formulation of the Susceptible-Infectious-Removed (SIR) epidemic model including host demography (births and deaths) and corresponds to the standard SIR ordinary differential equations (ODEs) in the infinite population limit. Exploiting a boundary layer approximation to the ODEs and a birth-death process approximation to the stochastic dynamics within the boundary layer, we derive convenient, fully analytical approximations for the burnout probability. We demonstrate—by comparing with computationally demanding individual-based stochastic simulations and with semi-analytical approximations derived previously—that our fully analytical approximations are highly accurate for biologically plausible parameters. We show that the probability of burnout always decreases with increased mean infectious period. However, for typical biological parameters, there is a relevant local minimum in the probability of persistence as a function of the basic reproduction numberR0. For the shortest infectious periods, persistence is least likely ifR0≈2.57; for longer infectious periods, the minimum point decreases toR0≈2. For typical acute immunizing infections in human populations of realistic size, our analysis of the SIR model shows that burnout is almost certain in a well-mixed population, implying that susceptible recruitment through births is insufficient on its own to explain disease persistence.
Update of the BIPM comparison BIPM.RI(II)-K1.Ge-68 of activity measurements of the radionuclide 68Ge to include the 2021 result of the NIM (China)
Authors: Michotte Carine , Coulon Romain , Courte Sammy , Gressier Vincent , Nonis Manuel , Liu Haoran , Liang Juncheng , Liu Meiling , Zhang Ming
Published: January 2024

Main text

Since 2013, 6 laboratories have submitted 7 samples of 68Ge to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)-K1.Ge-68. Recently, the NIM (China) participated in the comparison and the key comparison reference value (KCRV) has been updated. The degrees of equivalence

between each equivalent activity measured in the SIR or linked to the SIR from the CCRI(II)-K2.Ge-68 comparison and the updated KCRV have been calculated and the results are given in the form of a table. A graphical representation is also given.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Interception of Layered LP-N and HLP-N at Ambient Conditions by Confined Template
Authors: Wang 王 Dong-Xue 冬雪 , Fu 付 Jing 静 , Li 李 Yi 义 , Yao 姚 Zhen 震 , Liu 刘 Shuang 爽 , Liu 刘 Bing-Bing 冰冰
Published: January 2024

We propose a feasible strategy of intercepting the layered polymeric nitrogen (LP-N) and hexagonal layered polymeric nitrogen (HLP-N) at ambient conditions by using the confinement templates. The stable mechanism of confined LP-N and HLP-N at ambient conditions is revealed, namely the synergistic effect of charge transfer and vdW confinement effect. The influence rule of interlayer spacing on the stability of LP-N is revealed. Most importantly, the nitrogen content and energy density of recoverable LP-N@graphene (70.59%, 8.15 kJ/g), LP-N@h-BN (70.59%, 7.96 kJ/g), HLP-N@graphene (68.97%, 9.31 kJ/g), and HLP-N@h-BN (69.57%, 8.05 kJ/g) refresh the new record for the confinement polynitrogen system.
Another look at the current-carrying wire in special relativity
Authors: Smith Glenn S
Published: January 2024

In this paper we examine two models for a current-carrying wire in special relativity. The first model assumes an infinitely long wire and does not specify the source or return path for the current. This model is simple and easy to analyze, so it is often used in introductory textbooks to show the significance of special relativity for electromagnetism. The second model is a coaxial line with a battery at one end and a short circuit at the other. The center conductor of the line represents the wire of interest, and the outer conductor forms the return path for the current. The analysis for this model is more involved than that of the first model, but it provides information not available from that model. This new information answers questions a student might have when first encountering the simpler model.
CUQIpy: I. Computational uncertainty quantification for inverse problems in Python
Authors: Riis Nicolai A B , Alghamdi Amal M A , Uribe Felipe , Christensen Silja L , Afkham Babak M , Hansen Per Christian , Jørgensen Jakob S
Published: January 2024

This paper introduces CUQIpy, a versatile open-source Python package for computational uncertainty quantification (UQ) in inverse problems, presented as Part I of a two-part series. CUQIpy employs a Bayesian framework, integrating prior knowledge with observed data to produce posterior probability distributions that characterize the uncertainty in computed solutions to inverse problems. The package offers a high-level modeling framework with concise syntax, allowing users to easily specify their inverse problems, prior information, and statistical assumptions. CUQIpy supports a range of efficient sampling strategies and is designed to handle large-scale problems. Notably, the automatic sampler selection feature analyzes the problem structure and chooses a suitable sampler without user intervention, streamlining the process. With a selection of probability distributions, test problems, computational methods, and visualization tools, CUQIpy serves as a powerful, flexible, and adaptable tool for UQ in a wide selection of inverse problems. Part II of the series focuses on the use of CUQIpy for UQ in inverse problems with partial differential equations.
Thermal and hydraulic performance of Al alloy-based 3D printed triangular microchannel heatsink governed by rough walls with graphene and alumina nanofluids as working liquid
Authors: Nadarajah Puurnaraj , Mohamed Khairudin , Abdullah Jamaluddin , Devarajan Mutharasu
Published: January 2024

Microchannel heat sinks (MCHS) are known for providing enhanced cooling performance but their fabrication requires complex and multi-step processes. The recent development of additive manufacturing has enabled the fabrication of state-of-art monolithic structures that had been impossible to build using conventional methods. In this work, a monolithic cross-flow triangular cross-section MCHS was fabricated from aluminum alloy (AlSi10Mg) using the Direct Metal Laser Sintering (DMLS) process. The microchannel wall surface roughness was measured and the cross-section shrinkage of the microchannels was compared with the initial design hydraulic diameter of 500 µm–1000 µm. The MCHS with an initial design hydraulic diameter of 750 µm possessed a relative wall surface roughness, R
a of 7.7%. The triangular cross-section hydraulic diameter underwent a shrinkage of 15.2% and 5.3% in terms of the reduction in angle between adjacent side alloys. Experiments were conducted for Reynolds numbers between 50 and 275 with nanofluids containing graphene and Al2O3 nanoparticles in water/water +10% ethylene glycol; these were compared with their respective base fluids. The Poiseuille number indicated that flow was laminar developed with base fluid and laminar developing with nanofluid as coolant. Despite providing the lowest thermal resistance, the graphene nanoparticles in water created the greatest pressure drop leading to a reduced performance coefficient. Al2O3 nanoparticles in water/water +10% ethylene glycol were found to have 7.7% and 20% better performance coefficients than their respective base fluids.
Effect of bonding adhesive thickness on temperature characteristics and strain characteristics of SAW strain sensors
Authors: Liu Qiang , Yang Wenlong , Li Hongyuan , Xu Hong
Published: January 2024

Accurate measurement of physical parameters based on sensing technology is an important basis for equipment structural health monitoring technology. In harsh environments, strain measurement techniques based on SAW sensors have attracted much attention. The bonding adhesive is a key step in the strain measurement process, and its effect on the accuracy of the measurement results cannot be ignored. In this paper, the one-port resonant SAW strain sensor is prepared using LiNbO3 as a piezoelectric substrate, Pt as an electrode and SiO2 as a protective layer. The strain characteristics and temperature characteristics of SAW strain sensors at the thickness of the bonding adhesive (Model: DOUBLE-BOND CHEMICAL®DB5016) are explored. The frequency–temperature curves of the SAW sensors show a quasi-linear decreasing trend with increasing temperature, and the temperature–frequency characteristics are similar for different bonding adhesive thicknesses. The strain sensitivity increases and then decreases with increasing temperature, and reaches a maximum at 150 °C. An increase in the thickness of the bonding adhesive leads to a decrease in the temperature linearity and an increase in the temperature sensitivity of the SAW strain sensor, which is maximized at a bonding adhesive thickness of 0.35 mm. The increase in the thickness of the bonding adhesive leads to a decrease in the strain linearity and strain sensitivity of the SAW sensor. The relationship between the strain transfer efficiency of the SAW sensor and the thickness of the bonding layer, the shear modulus of the bonding layer, the length of the sensor, the thickness of the sensor substrate and the shear modulus of the sensor is established through theoretical derivation. A theoretical foundation is provided for the accurate measurement of strain based on SAW technology.
A compact and reconfigurable C-band DGS-based power divider using RF MEMS capacitive switch
Authors: Narang Niharika , Shrivastava Pranav Kumar , Basu Ananjan , Singh Pushpapraj
Published: January 2024

This article presents a reconfigurable and compact power divider design that utilizes a combination of defect structures in the ground plane (DGS) and capacitance loading using a unique RF MEMS switch on the sapphire substrate. The combination of these two techniques results in a reduced-size reconfigurable power divider, wherein the length of the quarter-wavelength transmission line is reduced to λ/16 from λ/4, and the higher-order harmonics are suppressed up to 40 GHz. The RF MEMS capacitive switch is designed, and its DC characteristics are simulated in coventorware. The RF characteristics of the designed power divider are simulated in Ansys HFSS 19.2. The power divider utilizing RF MEMS technology has been fabricated through surface micromachining, requiring only four masks for fabrication. According to measurement findings, insertion loss and return loss are 3.57 dB and 24.6 dB (at 4.4 GHz) and 3.82 dB and 22.06 dB (at 5.4 GHz) when the switch is on and off, respectively. The total area of the design is 3.1 mm2 (21.3% of the conventional power divider). The proposed design can suppress harmonics up to the 8th order by 10 dB. These features render it a viable option for employment in Radio Frequency Integrated Circuits (RFICs).
An adaptive enhanced envelope spectrum technique for bearing fault detection in conditions characterized by strong noise
Authors: Xv Jinglun , Liao Zihao , Cao Yuqi , Cao Yunqi , Hou Dibo , Huang Pingjie
Published: January 2024

Rolling bearings are widely used in rotating machinery and have a high failure rate. Regrettably, the task of ensuring dependable bearing fault detection presents a formidable challenge, especially when the bearing fault-related characteristics are non-stationary or even affected by strong noise. In response to this challenge, a novel adaptive enhanced envelope spectrum (AEES) technique is proposed in this study. Firstly, it generates representative intrinsic mode functions (IMFs) using the variational mode decomposition algorithm. Then, based on the analysis of the envelope spectrum normalized mutual information and time-domain fuzzy entropy, a new IMF selection and integration strategy combining time- and frequency-domain metrics is suggested to reconstruct the most informative analytical signal. An adaptive filter is employed to post-process the reconfigured signal to reinforce fault-related impulsive characteristics, the optimal length of which is ascertained through the proposed variable step-size search technique based on unbiased autocorrelation analysis. The efficacy of the AEES technique has been validated through a sequence of experiments conducted under diverse bearing conditions. Its robustness and distinct advantages under strong noise conditions are tested using a publicly available dataset. The validation results show that the AEES technique can effectively identify the health conditions of bearings under high noise conditions (signal-to-noise ratios between 1 dB and 3 dB). Compared with two relevant techniques in the existing literature and a classical method, the proposed AEES technique can achieve signal processing results with fewer interference components and more prominent characteristic frequency information and has a unique ability to identify fault features in some challenging situations.
External electric field and UV-ozone treated Ti3C2T
x
-MXene nanosheets and their hole injection tailoring in UV organic light-emitting diodes
Authors: Bai Wei , Wu Danni , Tang Yijin , Yi Zichuan , Chi Feng , Liu Liming , Zhang Xiaowen
Published: January 2024

Solution-processed 2D nanosheets of Ti3C2T
x
-MXene have been facilely synthesized with ultrasonic-assisted liquid phase exfoliation. X-ray diffraction, scanning electron microscope, transmission electron microscope, atomic force microscopy and x-ray photoelectron spectroscopy measurements confirm that the Ti3C2T
x
-MXene nanosheets have been successfully synthesized, showing good film morphology and exceptional electronic properties. The comprehensive properties of Ti3C2T
x
-MXene nanosheets are systematically optimized by combination with appropriate sizes of Ti3C2T
x
-MXene nanosheets, external electric field and ultraviolet (UV)-ozone treatment. With Ti3C2T
x
-MXene nanosheets as hole injection layer and PBD as emissive molecule, UV organic light-emitting diodes (OLEDs) have been configurated and shown superior performance with maximum radiance of 1.47 mW cm−2, maximum external quantum efficiency of 1.084% and electroluminescent peak around 400 nm. The effects of external electric field and UV-ozone treatment on hole injection ability of Ti3C2T
x
-MXene nanosheets are investigated in details and further analyzed with impedance spectroscopy. Our experiments pave an alternative approach for advancing Ti3C2T
x
-MXene nanosheets and UV OLEDs.
Surface passivation properties of atomic-layer deposited hafnium oxide on a (100) β-Ga2O3 MOSFET
Authors: Oh Seung Yoon , Lee Gyuhyung , Ma Jiyeon , Yoo Geonwook
Published: January 2024

We report the effect of HfO2 passivation on the electrical characteristics of (100) β-Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFETs). The atomic-layer-deposited HfO2 layer with negative defect charges enhances the transconductance and subthreshold slope. A significant positive threshold voltage (V
TH) shift of ∼32 V is induced after the passivation. Moreover, significantly less V
TH shift of ∼2 V is observed under negative bias stress (NBS) for 3600 s in comparison with an Al2O3 passivated and unpassivated device. Physics-based technology computer aided design (TCAD) simulation is performed to demonstrate the surface depletion effect and the dependency on the density of negative fixed charges in the HfO2 passivation layer. Finally, the HfO2 passivated device maintains superior electrical characteristics compared to the unpassivated device at a temperature of up to 500 K.
Design and simulation of a tunable comb-drive actuator with a wide frequency tuning range and low pull-in voltage
Authors: Taherian Sina , Gholinataj-Jelodar Ehsan , Yuan Ye
Published: January 2024

The presented paper describes the design, simulation, and analysis of a novel tunable comb-drive actuator that aims to increase the range of tuning resonance frequency while reducing the pull-in voltage. The conventional comb resonator has a limited resonant frequency tuning range, and hence, modifying the spring stiffness of the structure is crucial to obtaining a tunable comb resonator. The proposed design includes eight flexible beams on each side that support a set of comb finger parts. The actuator achieves the goal of shifting the resonance frequency both downwards and upwards by utilizing Serpentine nested-folded beams. A triangular comb with non-uniform varied finger lengths combined with variable gap fingers is designed to adjust the frequency downwards, while a comb with constant finger lengths combined with variable gap fingers is designed to adjust the frequency upwards. To simulate and design the structure, the IntelliSuite software is utilized. The results show that the actuator has a primary resonant frequency of 3052 Hz, which can be lowered to 335 Hz by applying a tuning voltage of 74 V to the downward tuning part. Similarly, the resonant frequency can be increased to 3159 Hz by applying a tuning voltage of 60 V to the upward tuning part. The resonator achieves a maximum frequency tuning range of 90%, and the simulation results are in good agreement with the theoretical predictions. However, it is worth noting that the size of this resonator is relatively small, approximately 1077 × 328 μm2. This innovative design offers potential applications in various fields, including micro-electromechanical systems (MEMS), micro-optics, and microsensors. Overall, the presented work demonstrates the feasibility of achieving a tunable comb resonator with a significantly improved resonant frequency tuning range and reduced pull-in voltage.
Exchange-spring behavior in Ni0.3Cu0.2Zn0.5Fe2O4/PbFe12O19 nanocomposite
Authors: Khodayari Kobra , Gholizadeh Ahmad
Published: January 2024

The structural and magnetic properties of the (1-x)Ni0.3Cu0.2Zn0.5Fe2O4/(x)PbFe12O19 nanocomposites were investigated, where x is the weight percentage of PbFe12O19 (hard phase) ranging from 0 to 100%. The magnetic measurement curves show a magnetic phase transition from soft to hard ferrimagnetic with an increasing weight percentage of the hard PbFe12O19 phase. For weight percentages of 30%, 45%, and 60% of PbFe12O19, the M
r/M
s ratio is more than 0.5 and they show a normal single-phase magnetic behaviour, indicating the formation of a strong exchange coupling in these samples. Compared to the single-phase Ni0.3Cu0.2Zn0.5Fe2O4 (soft phase), the saturation magnetization of the composites decreases significantly from 34.45 to 16.1 emu g−1 with increasing PbFe12O19 content, while the coercivity increases from 62 to 861 Oe. Although increasing the PbFe12O19 content reduces the saturation magnetization and increases the coercivity of the soft magnetic phase, this may provide a significant way to tune the magnetic properties with desired coercivity and saturation magnetization.
Detection of different drinkable milk using photonic crystal fibre biosensor in IR regime
Authors: Maidi Abdul Mu’iz , Kalam Md Abul , Begum Feroza
Published: January 2024

A simplified PCF sensor has been designed to detect the different drinkable milk that includes camel, cow and buffalo milk, and can also assess its quality. The sensor features a singular circular core design and two layers octagonal cladding air holes that was analysed using the Finite Element Method technique in COMSOL Multiphysics software and determine the sensing and optical performance parameters: power fraction, relative sensitivity, confinement loss, effective area, numerical aperture, V-Parameter, spot size, and beam divergence. At the optimum wavelength of 6.0 μm, the relative sensitivities are 96.58%, 96.78%, and 96.84%, and confinement losses of 3.51 × 10−8 dB/m, 1.47 × 10−8 dB m−1, and 8.59 × 10−9 dB/m, for camel, cow, and buffalo milk, respectively. The efficacy of the proposed PCF structure for sensing applications in the dairy industry in distinguishing between different types of milk is evidenced by these findings. Moreover, the results of confinement loss and chromatic dispersion suggest potential applications of this design in optical communication.
Synthesis of multilayer graphene and its graphene derivatives from coal
Authors: Zhao Ke , Cao Jianzhao , Qi Ying , Wei Peng , Cheng Jian , Xie Yahong
Published: January 2024

In our study, we selected three prevalent coal types from Xinjiang: Dahuangshan coal (referred to as Y-coal), Black Mountain coal (B-coal), and Kuche coal (K-coal). Initially, we assessed their morphological differences using electron microscopy. Subsequently, we evaluated the superiority of Y-coal through Thermogravimetric Analysis (TGA). Furthermore, we compared their performances using various electrochemical tests, including the J-V curve, dark current curve, open-circuit voltage curve, and Electrochemical Impedance Spectroscopy (EIS) curve. Ultimately, we investigated the potential of synthesizing graphene from Y-coal and its derivatives. The first step was the preparation of multilayer graphene (MG) by treating Y-coal with acid to obtain demineralized coal, followed by treatment in a tube furnace to obtain ultrafine powdered MG. The second step was then followed by successive oxidation and ultrasonication of the already obtained MG to obtain graphene oxide (GO). Finally, ascorbic acid (VC) was selected to treat GO to prepare an aqueous suspension of reduced graphene oxide (rGO). MG (2θ = 26.2°), GO (2θ = 12.4°) and rGO (2θ = 25.5°) were obtained by XRD analysis. C 1s and O 1S were analyzed by XPS spectra. The functional groups −OH, C=O, and −C=C–, which are unique to graphene and its derivatives, were comparatively analyzed using infrared spectroscopy. The change of π→π* was analyzed by the UV–vis method. The absorbance was further found in combination with PL spectra. Immediately after, the morphology of graphite and its derivatives was analyzed by SEM, HRTEM, the physical properties by contact angle and BET, and finally the content of elements C and O by EDS. The successful demonstration of the superiority of the synthesized MG and its derivatives was achieved.