bluuebunny/crossref_metadata_2025 huggingface dataset:
Volar Plate Draping (VPD) for Severely Comminuted Proximal Phalanx Head Fractures
Authors: Varadha Rajan Ashwini , Varadharajan Vigneswaran , Bhardwaj Praveen , Sabapathy S. Raja
Published: July 2024

While proximal phalangeal joint injuries with comminution of the base of the middle phalanx are common injuries, proximal interphalangeal (PIP) joint fracture dislocations with an intact base of middle phalanx and a comminuted head of proximal phalanx are rare. Volar plate arthroplasty and other described techniques prevail for the former injury, while the latter does not have any supportive literature on the exact method of management. We herein present a 20-year-old male with a severely comminuted head of proximal phalanx fracture with dislocation of the PIP joint, which was not reconstructable but was managed successfully with a novel technique of volar plate draping that resurfaced the raw phalangeal head. A 3-year follow-up of the patient, whose finger has full, painless, and complete functional range of movement, gives us the belief that this procedure can provide a fully functional finger where other methods fail to do so.
Effects of perceived situational factors on plastic packaging waste recycling behavior through environmental attitude
Authors: Ertz Myriam , Addar Walid , Tandon Urvashi , Zhang Ophela , Takaffoli Mahdi , Joued Leyla
Published: July 2024

This study explores the effects of perceived situational factors (cost, time, and effort) related to plastic packaging waste recycling behavior. It also examines the mediating role of environmental attitudes in this relationship. An online questionnaire-based survey administered to a pan-Canadian sample of 1000 respondents reveals that from an aggregate perspective, perceived situational factors positively and directly impact environmental attitudes and plastic packaging waste recycling. Because environmental attitude is also positively related to plastic recycling, environmental attitudes partially mediate the link between perceived situational factors and plastic recycling. From a piecemeal perspective, the perception of a higher degree of inexpensiveness, fastness, and effortlessness directly affects environmental attitudes and plastic packaging waste recycling. Hence, environmental attitude partially mediates the effect of consumers' perceived situational factors and explains their impact on plastic packaging waste recycling.
Perceptions of incarcerated people: prison conditions, public health, and justice in the United States
Authors: Hyatt Jordan M. , Andersen Synøve N. , van Tiem Britte
Published: July 2024

Carceral conditions in the United States may serve as a proxy for crises within justice and health systems. This study seeks to consider and measure prison climate from the perspective of incarcerated people. By examining within-facility differences in carceral experiences, results shed light on the complex nexus between the carceral context, health, and justice. We administered the Prison Climate Questionnaire (PCQ) to the complete population of incarcerated men in a correctional facility located in the Eastern United States. In this facility, housing units hold distinct populations, fulfill different functions, and can offer unique programming. We regress select items from the PCQ on a set of dummies corresponding to different residential units within the facility. Responses indicate low but relatively uniform perceptions of overall personal health, as well as access to, and satisfaction with, medical care. Between-unit differences emerge regarding staff relationships, experiences of discrimination, and levels of isolation. The perspectives of incarcerated people can, and should, play a role in understanding and conceptualizing the nature of the prison environment. Policy responses, especially those that impact the health and well-being of currently and formerly incarcerated people, can be informed by these perspectives.
Technology investment and insurer efficiency
Authors: Neale Faith Roberts , Drake Pamela Peterson , Jin Licheng , Lai Gene
Published: July 2024

We examine the role of technology expense and asset data items with insurer efficiency. We show that insurers increasing investment in technology classified as expenses, experience increases in allocative efficiency the following year. Insurers that increase expenditures classified as technology assets realize decreases in cost and allocative efficiency the next year. In addition, we find that expensed technology contains different information than those classified as assets with the association of expenditures in assets with efficiency dominating expensed technology. Our findings support that expensed technology items are for innovative applications and technology assets are used to support general business operations. We also explore the possibility that the reduction of commissions to agents is a mediator through which technology expenses affect efficiency, but do not find support for this mediation.
Photodynamic therapy offers an alternative to bariatric surgery
Authors: Johnson-Groh Mara
Published: July 2024

A procedure using a photosensitive metal stent opens a potential avenue for the treatment of metabolic syndrome.
Some spectral comparison results on infinite quantum graphs
Authors: Bifulco P. , Kerner J.
Published: July 2024

In this paper we establish spectral comparison results for Schrödinger operators on a certain class of infinite quantum graphs, using recent results obtained in the finite setting. We also show that new features do appear on infinite quantum graphs such as a modified local Weyl law. In this sense, we regard this paper as a starting point for a more thorough investigation of spectral comparison results on more general infinite metric graphs.
Elucidating the transport of water and ions in the nanochannel of covalent organic frameworks by molecular dynamics
Authors: Xie Yahui , Huang Chuan-Qi , Zhou Ke , Liu Yilun
Published: July 2024

Inspired by biological channels, achieving precise separation of ion/water and ion/ion requires finely tuned pore sizes at molecular dimensions and deliberate exposure of charged groups. Covalent organic frameworks (COFs), a class of porous crystalline materials, offer well-defined nanoscale pores and diverse structures, making them excellent candidates for nanofluidic channels that facilitate ion and water transport. In this study, we perform molecular simulations to investigate the structure and kinetics of water and ions confined within the typical COFs with varied exposure of charged groups. The COFs exhibit vertically arrayed nanochannels, enabling diffusion coefficients of water molecules within COFs to remain within the same order of magnitude as in the bulk. The motion of water molecules manifests in two distinct modes, creating a mobile hydration layer around acid groups. The ion diffusion within COFs displays a notable disparity between monovalent (M+) and divalent (M2+) cations. As a result, the selectivity of M+/M2+ can exceed 100, while differentiation among M+ is less pronounced. In addition, our simulations indicate a high rejection (R > 98%) in COFs, indicating their potential as ideal materials for desalination. The chemical flexibility of COFs indicates that would hold significant promise as candidates for advanced artificial ion channels and separation membranes.
The origins of dual-peak emission and anomalous exciton decay in 2D Sn-based perovskites
Authors: Wang Xinrui , Wei Yingqiang , Kuang Zhiyuan , Wang Xing , Dai Mian , Li Xiuyong , Lu Runqing , Liu Wang , Chang Jin , Ma Chao , Huang Wei , Peng Qiming , Wang Jianpu
Published: July 2024

Two-dimensional (2D) Sn-based perovskites exhibit significant potential in diverse optoelectronic applications, such as on-chip lasers and photodetectors. Yet, the underlying mechanism behind the frequently observed dual-peak emission in 2D Sn-based perovskites remains a subject of intense debate, and there is a lack of research on the carrier dynamics in these materials. In this study, we investigate these issues in a representative 2D Sn-based perovskite, namely, PEA2SnI4, through temperature-, excitation intensity-, angle-, and time-dependent photoluminescence studies. The results indicate that the high- and low-energy peaks originate from in-face and out-of-face dipole transitions, respectively. In addition, we observe an anomalous increase in the non-radiative recombination rate as temperature decreases. After ruling out enhanced electron–phonon coupling and Auger recombination as potential causes of the anomalous carrier dynamics, we propose that the significantly increased exciton binding energy (Eb) plays a decisive role. The increased Eb arises from enhanced electronic localization, a consequence of weakened lattice distortion at low temperatures, as confirmed by first-principles calculations and temperature-dependent x-ray diffraction measurements. These findings offer valuable insights into the electronic processes in the unique 2D Sn-based perovskites.
Role of heads and tails on tetrahydrofuran- and dimethyl sulfoxide-water separation by glycerol and sucrose esters
Authors: Bartokova Bibiana , Marangoni Alejandro G. , Pensini Erica
Published: July 2024

Tetrahydrofuran (THF) and dimethylsulfoxide (DMSO) are miscible in water due to hydrogen (H) bonding. Amphiphilic glycerol and sucrose esters with a different number of tails and heads separate them, depending on the organic solvent concentration. Separation is worse in solutions where amphiphiles are most soluble. Separation occurs due to interactions between the amphiphiles and either organic solvents or water, as shown by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Separation is best with glycerol esters with more heads and tails. Multiple tails hamper interactions between glycerol ester heads, thereby facilitating interactions with organic solvents or water to promote solvent–water separation. THF interacts with the glycerol ester tails, while water H bonds with the glycerol ester heads, as indicated by activity coefficients estimated with conductor-like screening model for real solvents. In THF, amphiphiles self-assemble into micelles, as shown by small angle x ray scattering (SAXS). Without water, THF is likely both inside and outside the micelles. SAXS shows that micelles shrink with 4% water in THF because water molecules partition inside them and are smaller than THF. With additional water, micelles swell into emulsions. Dissimilar to THF, DMSO preferentially interacts with the glycerol ester heads rather than their tails. ATR-FTIR shows that the proportion of free vs bonded S=O groups of DMSO decreases upon mixing with glycerol esters. DMSO and glycerol esters primarily accept H bonds, as indicated by their sigma profile. This leads to competition for interactions with water, displacing DMSO.
Magnetization and exchange-stiffness constants of Fe–Al–Si alloys at finite temperatures: A first-principles study
Authors: Yamashita Shogo , Sakuma Akimasa
Published: July 2024

We investigated the magnetic properties of Sendust (Fe-Al-Si) alloys not only at 0 K but also at finite temperatures by means of the first-principles calculations assuming A2, B2, and D03 structures. We confirmed that the itinerant characteristics of 3d electrons of Fe are not negligible and a significantly small exchange stiffness constant exists at zero temperature in a B2 structure. However, the calculated Curie temperatures are in the same order for all structures; this indicates that the Curie temperature cannot be determined only by the exchange interactions at zero temperature in itinerant electron systems. Temperature dependence of the exchange interaction, namely, spin configuration dependence, also might be important for determining it. In addition, this property might also be related to the unique behavior of the temperature dependence of the exchange stiffness constant for the B2 structure, which does not decrease monotonically as temperatures increase, contrary to the behavior expected from the Heisenberg model. In addition, we investigated composition dependence on the exchange stiffness constant at zero temperature and confirmed that the substitution of Si with Al could improve the amplitude of the exchange stiffness constant at zero temperature for all structures.
Room-temperature strong coupling between CdSe nanoplatelets and a metal–DBR Fabry–Pérot cavity
Authors: Morshed Ovishek , Amin Mitesh , Cogan Nicole M. B. , Koessler Eric R. , Collison Robert , Tumiel Trevor M. , Girten William , Awan Farwa , Mathis Lele , Huo Pengfei , Vamivakas A. Nickolas , Odom Teri W. , Krauss Todd D.
Published: July 2024

The generation of exciton–polaritons through strong light–matter interactions represents an emerging platform for exploring quantum phenomena. A significant challenge in colloidal nanocrystal-based polaritonic systems is the ability to operate at room temperature with high fidelity. Here, we demonstrate the generation of room-temperature exciton–polaritons through the coupling of CdSe nanoplatelets (NPLs) with a Fabry–Pérot optical cavity, leading to a Rabi splitting of 74.6 meV. Quantum–classical calculations accurately predict the complex dynamics between the many dark state excitons and the optically allowed polariton states, including the experimentally observed lower polariton photoluminescence emission, and the concentration of photoluminescence intensities at higher in-plane momenta as the cavity becomes more negatively detuned. The Rabi splitting measured at 5 K is similar to that at 300 K, validating the feasibility of the temperature-independent operation of this polaritonic system. Overall, these results show that CdSe NPLs are an excellent material to facilitate the development of room-temperature quantum technologies.
Final nanoparticle size distribution under unusual parameter regimes
Authors: Sabbioni Elena , Szabó Rebeka , Siri Paola , Cappelletti Daniele , Lente Gábor , Bibbona Enrico
Published: July 2024

We explore the large-scale behavior of a stochastic model for nanoparticle growth in an unusual parameter regime. This model encompasses two types of reactions: nucleation, where n monomers aggregate to form a nanoparticle, and growth, where a nanoparticle increases its size by consuming a monomer. Reverse reactions are disregarded. We delve into a previously unexplored parameter regime. Specifically, we consider a scenario where the growth rate of the first newly formed particle is of the same order of magnitude as the nucleation rate, in contrast to the classical scenario where, in the initial stage, nucleation dominates over growth. In this regime, we investigate the final size distribution as the initial number of monomers tends to infinity through extensive simulation studies utilizing state-of-the-art stochastic simulation methods with an efficient implementation and supported by high-performance computing infrastructure. We observe the emergence of a deterministic limit for the particle’s final size density. To scale up the initial number of monomers to approximate the magnitudes encountered in real experiments, we introduce a novel approximation process aimed at faster simulation. Remarkably, this approximating process yields a final size distribution that becomes very close to that of the original process when the available monomers approach infinity. Simulations of the approximating process further support the conjecture of the emergence of a deterministic limit.
Parametric investigation of aerodynamic performance degradation due to icing on a symmetrical airfoil
Authors: Nath Pranav , Lokanathan Nipin , Wang Jeremy , Benmeddour Ali , Nichman Leonid , Ranjbar Keyvan , Hickey Jean-Pierre
Published: July 2024

Ice accretion on lifting surfaces induces an aerodynamic penalty in lift and drag on an aircraft. This performance degradation depends on the geometric features, type, and surface characteristics of the accreted ice on the airfoil. In the present work, we propose a set of two-parameter, low-order models to represent some of the typical ice topologies: glaze, rime, and horn. The parametric space is swept for all types of ice to isolate the aerodynamic changes causing performance degradation on a canonical symmetrical airfoil, which is the representative airfoil used by the National Research Council of Canada's platform for ice accretion and coatings tests with ultrasonic readings platform for in-flight icing tests. The three ice topologies show a self-similar trend between the stall angle of attack and the ice thickness, with the horn-type of ice imparting the greatest drag and lift penalty due to strong boundary layer separation. The relative effect of ice roughness plays a secondary role in performance degradation, and in some cases, the roughness causes a thicker and more resilient boundary layer, which can, under very specific icing conditions, enhance the aerodynamic performance.
Natural Language Processing for Ancient Greek
Authors: Stopponi Silvia , Pedrazzini Nilo , Peels-Matthey Saskia , McGillivray Barbara , Nissim Malvina
Published: July 2024

Computational methods have produced meaningful and usable results to study word semantics, including semantic
change. These methods, belonging to the field of Natural Language Processing, have recently been applied to ancient languages; in
particular, language modelling has been applied to Ancient Greek, the language on which we focus. In this contribution we explain
how vector representations can be computed from word co-occurrences in a corpus and can be used to locate words in a semantic space,
and what kind of semantic information can be extracted from language models. We compare three different kinds of language models
that can be used to study Ancient Greek semantics: a count-based model, a word embedding model and a syntactic embedding model;
and we show examples of how the quality of their representations can be assessed. We highlight the advantages and potential of
these methods, especially for the study of semantic change, together with their limitations.
Discourse and transformation
Authors: Jiang Xiangyi , Zhang Chenxia
Published: July 2024

This paper sets out to investigate the representation of energy in China’s diplomatic discourse in a context where
power structures within and among nation-states are shifting and energy is becoming more politicized. To do this, this research
adopts corpus-assisted discourse-historical analysis to examine discursive strategies and investigates the way energy is
constructed in China’s diplomacy. Results show a dichotomy of an active ingroup and an indifferent outgroup, revealing a reversal
of power in the fierce competition of discourse in the international energy sector, which serves as a catalyst for the creation of
demand for new energy sources and the development of new energy industries. The analysis of grounded linguistic evidences also
signifies that discourse is the site where power is not only enacted and performed, but also negotiated and contested.
Shape and parameter identification by the linear sampling method for a restricted Fourier integral operator
Authors: Audibert Lorenzo , Meng Shixu
Published: July 2024

In this paper we provide a new linear sampling method based on the same data but a different definition of the data operator for two inverse problems: the multi-frequency inverse source problem for a fixed observation direction and the Born inverse scattering problems. We show that the associated regularized linear sampling indicator converges to the average of the unknown in a small neighborhood as the regularization parameter approaches to zero. We develop both a shape identification theory and a parameter identification theory which are stimulated, analyzed, and implemented with the help of the prolate spheroidal wave functions and their generalizations. We further propose a prolate-based implementation of the linear sampling method and provide numerical experiments to demonstrate how this linear sampling method is capable of reconstructing both the shape and the parameter.
Large stroke electromagnetic redundant actuated six degrees-of-freedom parallel compliant micropositioning stage
Authors: Xie Chao , Lai Leijie , Chen Yunzhuang , Zhu Limin
Published: July 2024

In this paper, a novel large stroke six degrees-of-freedom (6-DOF) electromagnetic redundant actuated micropositioning stage is proposed. The 6-DOF stage adopts a configuration that is composed of eight parallel driving branch chains. Each branch chain is driven by a voice coil motor and incorporates a parallelogram flexure mechanism and a decoupling mechanism for guidance and decoupling. The positioning stage is symmetrically arranged and possesses the advantages of simple structure and easy assembly. As a result, assembly errors are significantly reduced and positioning accuracy is enhanced. The decoupling mechanism uses a large stroke flexible ball joint that increases the motion range of the positioning stage and decouples the coupled motion, thereby enhancing the stability and accuracy of the stage. To evaluate the performance of the stage, static and dynamic analytical models of the 6-DOF stage are derived based on the compliance matrix method and the Lagrangian dynamic modeling method. Additionally, the accuracy of the analytical models and the static and dynamic performances of the positioning stage are verified through finite element analysis (FEA) and experimental testing. The experimental results demonstrate that the stage realizes a workspace of 2.06 mm × 2.02 mm × 3.1 mm × 23.4 mrad × 23.1 mrad × 14.9 mrad. Finally, to verify the tracking performance trajectory of the 6-DOF positioning stage, tracking experiments are performed using a controller that combines a proportional-integral controller and a notch filter.
Influence of orbital angular momentum of light on random spin-split modes in disordered anisotropic optical media
Authors: Panda Anwesha , Dey Sneha , Panda Yogishree Arabinda , Dash Aditya Anurag , Jana Aloke , Ghosh Nirmalya
Published: July 2024

Spin–orbit interaction of light in a disordered anisotropic medium is known to yield spin split modes in the momentum domain because of the random spatial gradient of the geometric phase of light. Here, we have studied the statistics of such spin-split modes for beams carrying intrinsic orbital angular momentum through the quantification of momentum domain entropy and investigated its dependence on various beam parameters. The influence of the spatial structure of the beam and the phase vortex on the statistics of the spin split modes were separately investigated using input Laguerre–Gaussian and Perfect Vortex beams passing through a disordered anisotropic medium with controlled input disorder parameter, which was realized by modulating the pixels of a liquid crystal-based spatial light modulator. The results of systematic investigations on the impact of beam waist, spot size and topological charge of the vortex beam show that the influence of the spot size on the emergence of the random spin split modes is much more significant as compared to the other beam parameters.
Formation of {111} oriented domains during the sputtering epitaxy growth of (001) oriented Iridium films
Authors: Weippert Jürgen , Kirste Lutz , Straňák Patrik , Sundarapandian Balasubramanian , Engels Jan , Oeser Sabine , Graff Andreas , Lebedev Vadim
Published: July 2024

In the wafer-scale growth of Ir(001) on yttria-stabilized zirconia (YSZ) by magnetron sputtering epitaxy two kinds of {111} oriented domains are observed. One consists of sharp ‘fjord’-shaped features in which four 90° alternated rotational variants of {111} are possible and the second one consists of islands with less defined shapes in which eight 45° alternated rotational variants can be found. Their formation occurs directly at the Ir/YSZ interface along incoherent grain boundaries, likely nucleating at local defects of the YSZ surface. In order to avoid these misoriented domains, process separation and proper etching pretreatment of the wafers both before and between the sputtering processes have been found to be the key strategy for achieving reproducibility and overall better material quality.
Spin–wave dynamics in perpendicularly magnetized antidot multilayers
Authors: De Anulekha , Pal Semanti , Hellwig Olav , Barman Anjan
Published: July 2024

Using all-optical time-resolved magneto-optical Kerr effect measurements we demonstrate an efficient modulation of the spin–wave (SW) dynamics via the bias magnetic field orientation around nanoscale diamond shaped antidots that are arranged on a square lattice within a [Co(0.75 nm)/Pd(0.9 nm)]8 multilayer with perpendicular magnetic anisotropy (PMA). Micromagnetic modeling of the experimental results reveals that the SW modes in the lower frequency regime are related to narrow shell regions around the antidots, where in-plane (IP) domain structures are formed due to the reduced PMA, caused by Ga+ ion irradiation during the focused ion beam milling process of antidot fabrication. The IP direction of the shell magnetization undergoes a striking change with magnetic field orientation, leading to the sharp variation of the edge localized (shell) SW modes. Nevertheless, the coupling between such edge localized and bulk SWs for different orientations of bias field in PMA systems gives rise to interesting Physics and attests to new prospects for developing energy efficient and hybrid-system-based next-generation nanoscale magnonic devices.
Temperature calibration of sample rods for neutron diffraction apparatus in the range of 6–473 K
Authors: Zhang Kai , Su Yulei , Zhou Jiayi , Wang Dongdong , Ding Huaikuang , Zhang Huabiao
Published: July 2024

Internal stresses play a crucial part in determining a material’s properties, which emphasizes the significance of accurate stress measurement and analysis. Neutron diffraction technology is a very promising approach to studying the complex microstructural properties of many materials, especially with the growing demand for cryogenic studies. This new device has a robust load capacity of 50 kN and works smoothly in a wide temperature range of 6 K–473 K. Furthermore, the diffraction angle is 47 degrees broader. Regardless of the samples, we observed that a thermal balance point existed close to 180 K. Importantly, thermal resistance was eliminated by the use of an analytical method, which has an extraordinarily small error of 2%. Using this exact calibration methodology ensures that the sample temperature is accurate during the experiments. This work presents a crucial apparatus for investigating the complexity of internal stresses in materials and offers an effective method for estimating and managing sample temperatures while doing research.
Compositional effects of hybrid MoS2–GO active layer on the performance of unipolar, low-power and multistate RRAM device
Authors: R Manikandan , Raina Gargi
Published: July 2024

Currently, 2D nanomaterials-based resistive random access memory (RRAMs) are explored on account of their tunable material properties enabling fabrication of low power and flexible RRAM devices. In this work, hybrid MoS2–GO based active layer RRAM devices are investigated. A facile hydrothermal co-synthesis approach is used to obtain the hybrid materials and a cost-effective spin coating method adopted for the fabrication of Ag/MoS2–GO/ITO RRAM devices. The performance of the fabricated hybrid active layer RRAM device is analysed with respect to change in material properties of the synthesized hybrid material. The progressive addition of 0.5, 1.5, 2.5 and 4.5 weight % of GO to MoS2, results in a hybrid active layer with higher intermolecular interaction, in the case of Ag/MoS2–GO4.5/ITO RRAM device, resulting in a unipolar resistive switching RRAM behavior with low SET voltage of 1.37 V and high I
on/I
off of 200 with multilevel resistance states. A space charge limited conduction mechanism is obtained during switching, which may be attributed to the trap states present due to functional groups of GO. The increased number of conduction pathways on account of both Ag+ ions and oxygen vacancies (Vo
2+), participating in the formation of conducting filament, results in higher I
on/I
off. This is the first report of unipolar Ag/MoS2–GO/ITO RRAM devices, which are particularly important in realizing high density crossbar memories for neuromorphic and in-memory computing as well as enabling flexible 2D nanomaterials-based memristor applications.
Nanostructure engineering in organic semiconductor devices toward interface matching
Authors: Bok Moonjeong , Jeong Jun-Ho , Lim Eunju
Published: July 2024

The performance of organic semiconductor devices with heterojunctions between the organic semiconductors and electrodes can be improved by reducing the contact resistance. In this study, we have developed nanopatterned electrodes that gradually change the impedance at the interface between the metal and organic semiconductor in organic devices, which were fabricated in periodic patterns using nanoimprint lithography. The imprint pattern spacing was changed to control the interface between the metal and organic semiconductor to ensure smooth carrier injection. We analyzed the carrier injection based on the pattern spacing of the electrode interface using electrical current–voltage and capacitance–frequency measurements in the diode. Subsequently, we analyzed the improved current mechanism through numerical simulation. Therefore, this study suggests the possibility of designing the interface of an organic device using the nanostructure between the organic semiconductor and carrier injection electrode.
Multi-wavelength and broadband plasmonic switching with V-shaped plasmonic nanostructures on a VO2 coated plasmonic substrate
Authors: Dalal Kirti , Sharma Yashna
Published: July 2024

In this paper, periodic arrays of identical V-shaped gold nanostructures and variable V-shaped gold nanostructures are designed on top of a gold-coated silicon dioxide (SiO2) substrate with a thin spacer layer of vanadium dioxide (VO2) to realize multi-wavelength and broadband plasmonic switches, respectively. The periodic array of identical V-shaped nanostructures (IVNSs) with small inter-particle separation leads to coupled interactions of the elementary plasmons of a V-shaped nanostructure (VNS), resulting in a hybridized plasmon response with two longitudinal plasmonic modes in the reflectance spectra of the proposed switches when the incident light is polarized in the x-direction. The x-direction is oriented along the axis that joins the V-junctions of all VNSs in one unit cell of the periodic array. On exposure to temperature, electric field, or optical stimulus, the VO2 layer transforms from its monoclinic semiconducting state to its rutile metallic state, leading to an overall change in the reflectance spectra obtained from the proposed nanostructures and resulting in an efficient multi-wavelength switching action. Finite difference time domain modelling is employed to demonstrate that an extinction ratio (ER) >12 dB at two wavelengths can be achieved by employing the proposed switches based on periodic arrays of IVNSs. Further, plasmonic switches based on variable V-shaped nanostructures—i.e. multiple VNSs with variable arm lengths in one unit cell of a periodic array—are proposed for broadband switching. In the broadband operation mode, we report an ER >5 dB over an operational wavelength range >1400 nm in the near-IR spectral range spanning over all optical communication bands, i.e. the O, E, S, C, L and U bands. Further, it is also demonstrated that the wavelength of operation for these switches can be tuned by varying the geometrical parameters of the proposed switches. These switches have the potential to be employed in communication networks where ultrasmall and ultrafast switches with multi-wavelength operation or switching over a wide operational bandwidth are inevitably required.
Study of temperature-dependent copper iodide thin film by thermal evaporation system
Authors: Biswal Sameer Ranjan , Pradhan Diana , Gartia Anurag , Sahoo Kiran Kumar , Sabat Somesh , Kar Jyoti Prakash
Published: July 2024

The development of heterostructure devices has gained significant attention towards scientific communities in the present time. This article reports on the effective use of the horizontal thermal evaporation (TE) method to successfully fabricate copper iodide (CuI) films on silicon (Si) substrates. By using the TE technique, CuI-based heterojunctions have been fabricated in this research . CuI exhibits semiconductor qualities of the p-type, making it a promising option for optoelectronic devices in the future. The temperature was varied from room temperature (RT) to 230 °C to synthesise the CuI/Si heterojunction. The structural, morphological, optical, and electrical analyses have been carried out with various substrate temperatures. The x-ray diffraction (XRD) data shows that the CuI films have demonstrated a polycrystalline character and have lattice parameters of 6.03 Å. The Raman spectroscopy study shows the microstructural analysis of CuI films. The field emission scanning electron microscopy (FESEM) study reveals the variation of grain size and shape with synthesis temperature. The atomic force microscope (AFM) was used to estimate the surface roughness. The CuI films were found to be p-type by the Hall effect measurement. The sample synthesised at 130 °C shows the highest mobility of 83.12 cm2 V−1 s−1 with a carrier concentration of 1019 cm−3. The UV-visible (UV–vis) spectroscopy measurements show good absorption of UV light by the CuI thin films. The CuI/Si heterojunctions are rectifying, as demonstrated by the I-V measurements, and those respond well to UV light irradiation.
BDS-3 full-frequency precise point positioning: models and performance comparison
Authors: Wang Cancan , Pan Lin
Published: July 2024

With the BDS-3 six-frequency integration, there are more choices to implement the precise point positioning (PPP) technology. To take full advantage of the multi-frequency combination, six typical BDS-3 six-frequency PPP models using uncombined observation (UC), five dual-frequency ionospheric-free (IF) combinations (IF2), four triple-frequency IF combinations (IF3), three four-frequency IF combinations (IF4), two five-frequency IF combinations (IF5), and a single six-frequency IF combination (IF6) were constructed and compared. The results indicate that the positioning accuracies of the six models are similar. The static positioning accuracies reach 4, 3–5, and 12–14 mm in the east, north, and up directions, respectively, while the kinematic positioning accuracies are 24–26, 16–17, and 42–43 mm, respectively. Regarding the convergence times, the UC model is slightly worse than the five IF combined models, except for some cases in the up direction. In the static mode, benefiting from the smallest noise amplification factor, the average convergence times of the IF6 model are the shortest, reaching 12.1, 5.5, and 13.4 min in the three directions, respectively, and are 7%, 15%, and 6% shorter than those of the UC model. In the kinematic mode, with the combination of more signals into a single IF combination, the noise level of the IF combined observables gradually decreases, but the convergence times gradually increase. The kinematic average convergence times of the IF2 model are 15.3, 3.6, and 18.0 min in the three directions, which are 6%, 22%, and 10% and 1%, 16%, and 20% shorter than those of the UC and IF6 models, respectively. In addition, the observation residuals, and the estimates of inter-frequency bias, tropospheric zenith wet delay, and receiver clock offsets from different models were compared and analyzed. The specific selection of the model should be based on actual situations.
A surface and corrosion characterisation of micro arc oxidation treated friction stir welded ZM21 and ZE41 magnesium alloy: a comparison study
Authors: Monish P , Hari Krishna KL , Rajkumar K
Published: July 2024

Magnesium alloys have gained attention as promising materials in industrial applications, for their high specific strength and low density. Magnesium alloys have desirable mechanical properties, but their poor corrosion resistance prevents their safe implementation. Alloys such as ZM21 and ZE41, possess unique properties that provide improved machinability and increased red-hot strength, respectively, while remaining prone to corrosion. To improve corrosion resistance, surface treatments and coating processes are employed. Comparing the corrosion characteristics of ZM21 and ZE41 is vital for aerospace and automotive applications, directly affecting component durability, reliability, and performance against corrosion. Magnesium alloys are frequently joined through friction stir welding (FSW), hence, similar importance is provided to studying the corrosion performance of welds, since FSW introduces microstructural changes that alter corrosion performance of welded joints. The paper discusses electrochemical corrosion mechanisms and analyzes the effect of Micro Arc Oxidation (MAO) coating on electrode potential, passivity, and electrical resistance of ZM21 and ZE41 plates welded through FSW. MAO treatments were performed on both base material and FSW joints. The corrosion performance of MAO-coated FSWed ZM21 and ZE41 alloys was compared through the Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarisation (PDP) tests. The PDP test revealed that MAO treatment enhanced the corrosion resistance of both base and FSWed ZM21 and ZE41 magnesium alloys. There was an improvement in potential polarization (Rp) values from 565 Ω cm2 to 11245 Ω cm2 for ZM21 and from 1184.4 Ω cm2 to 11435.69 Ω cm2 for ZE41 alloys. While exhibiting improvements in corrosion resistance, MAO-treated ZE41 performed better than MAO-treated ZM21. PDP results were verified through confirmatory EIS results. Therefore, MAO treatments are effective methods to improve the corrosion performance of Mg alloys. Evaluation of MAO coating performance on various FSW Mg alloys and studying their corrosion performance is crucial for engineering material selection.
Visually secure encryption embedded with multiple types of images using semi-tensor product compressed sensing
Authors: Fu Jianzhao , Guo Peilian
Published: July 2024

An image encryption scheme with visual security is designed by combining the semi-tensor product compressed sensing (STP-CS) with multi-embedding strategy. Specifically, the optimized measurement matrix is firstly generated by chaotic system and singular value decomposition (SVD), and the optimized measurement matrix is used to obtain the measurement value matrix by STP-CS operation on the color image. Next, the reorganized measurement value matrix is scrambled and diffused with the key matrix generated by 2D Logistic-Sine-coupling map (2D-LSCM) to obtain the noise-like encrypted image. Finally, an image embedding method is introduced to embed the compressed noise-like encrypted image into a color or grayscale carrier image to obtain a visually secure color or grayscale encrypted image. SHA-256 is used to generate the initial values of chaotic systems, which are embedded into the carrier image to effectively reduce transmission and storage. The simulation results show that the visually secure encryption scheme is more reliable and outperforms other encryption algorithms.
Dynamics of a restricted (6 + 1)-vortex problem
Authors: Liu Qihuai , Chen Yufei , Xie An
Published: July 2024

This paper investigates the dynamics of a restricted (6 + 1)-vortex problem. The existence of nested equilateral triangle configurations depends on the position of two triangles, which can be divided into two situations: staggered arrangement and symmetrical arrangement. Firstly, we provide the existence conditions for the configuration and further discuss the stability of the configuration numerically. Secondly, we have established the global dynamics of the restricted point-vortex problem with configurations under different arrangements, including the dynamic behavior of equilibrium points, periodic orbits, homoclinic orbits, and heteroclinic orbits.
Quantum effects on the evaporation of PBHs: contributions to dark matter
Authors: Haque Md Riajul , Maity Suvashis , Maity Debaprasad , Mambrini Yann
Published: July 2024

We compute the relic abundance of dark matter in the presence of Primordial Black Holes (PBHs) beyond the semiclassical approximation. We take into account the quantum corrections due to the memory burden effect, which is assumed to suppress the black hole evaporation rate by the inverse power of its own entropy. Such quantum effect significantly enhances the lifetime, rendering the possibility of PBH mass ≲ 109g being the sole dark matter (DM) candidate. However, Nature can not rule out the existence of fundamental particles such as DM. We, therefore, include the possibility of populating the dark sector by the decay of PBHs to those fundamental particles, adding the contribution to stable PBH whose lifetime is extended due to the quantum corrections. Depending on the strength of the burden effect, we show that a wide range of parameter space opens up in the initial PBH mass and fundamental dark matter mass plane that respects the correct relic abundance.
Feedback in the dark: a critical examination of CMB bounds on primordial black holes
Authors: Agius Dominic , Essig Rouven , Gaggero Daniele , Scarcella Francesca , Suczewski Gregory , Valli Mauro
Published: July 2024

If present in the early universe, primordial black holes (PBHs) would have accreted matter and emitted high-energy photons, altering the statistical properties of the Cosmic Microwave Background (CMB). This mechanism has been used to constrain the fraction of dark matter that is in the form of PBHs to be much smaller than unity for PBH masses well above one solar mass. Moreover, the presence of dense dark matter mini-halos around the PBHs has been used to set even more stringent constraints, as these would boost the accretion rates.
In this work, we critically revisit CMB constraints on PBHs taking into account the role of the local ionization of the gas around them. We discuss how the local increase in temperature around PBHs can prevent the dark matter mini-halos from strongly enhancing the accretion process, in some cases significantly weakening previously derived CMB constraints. We explore in detail the key ingredients of the CMB bound and derive a conservative limit on the cosmological abundance of massive PBHs.
Computationally efficient adaptive optimization of vector-method parameters for phase-sensitive strain estimation in optical coherence elastography
Authors: Zykov Alexey A , Matveyev Alexander L , Matveev Lev A , Assaad Maher , Zaitsev Vladimir Y
Published: July 2024

A new method for automatic adaptive optimization of strain estimation in phase-sensitive optical coherence tomography (OCT) is introduced. More specifically, this paper focuses on optimizing the estimation of strain using the vector method, in which OCT signals are treated as vectors in the complex plane. In phase-sensitive optical coherence elastography, the tissue strain is extracted from the interframe phase variation between the complex-valued scans acquired for the initial and deformed tissue. This phase variation is proportional to interframe displacements of scatterers and corresponds to the argument of the pixel-by-pixel product of the initial OCT scan and complex-conjugate deformed scan. Measurement noises and the so-called ‘speckle noise’ that are intrinsic to OCT scans cause degradation of the derived scan obtained by such multiplication. To mitigate the noise influence, complex-valued pixel amplitudes in the derived scan are usually averaged over a certain window. The interframe strain is found by estimating the gradient of the interframe phase difference. The noise influence on the strain estimation can also be reduced by increasing the scale over which the phase-variation gradient is estimated. However, choosing a too large window for preliminary averaging may significantly distort the reconstructed strain distribution. Similarly, a too large scale for gradient estimation may also cause errors in the estimated-strain magnitude and even its sign (because of possible phase wrapping). Therefore, appropriately performed adaptive choice of the strain-estimation parameters can greatly improve the quality of strain estimation. Here, we present a unified approach for adaptive choice of both the averaging-window size and gradient-estimation scale that were initially considered separately. The new method is computationally simplified but enables approximately the same strain-estimation quality, as demonstrated using both simulated and experimental OCT data.
Leading-edge curvature effect on aerodynamic performance of flapping wings in hover and forward flight
Authors: Addo-Akoto Reynolds , Han Jong-Seob , Han Jae-Hung
Published: July 2024

This study investigates the role of leading-edge (LE) curvature in flapping wing aerodynamics considering hovering and forward flight conditions. A scaled-up robotic model is towed along its longitudinal axis by a rack gear carriage system. The forward velocity of the robotic model is changed by varying the advance ratio J from 0 (hovering) to 1.0. The study reveals that the LE curvature has insignificant influence on the cycle-average aerodynamic lift and drag. However, the time-history lift coefficient shows that the curvature can enhance the lift around the middle of downstroke. This enhanced lift is reduced from 5% to 1.2% as J changed from 0 to 1.0. Further flow examinations reveal that the LE curvature is beneficial by enhancing circulation only at the outboard wing sections. The enhanced outboard circulation is found to emanate from the less stretched leading-edge vortices (LEVs), weakened trailing-edge vortices (TEVs), and the coherent merging of the tip vortices (TVs) with the minor LEVs as observed from the phase-lock planar digital particle image velocimetry measurements. The far-wake observation shows that the LE curvature enhances the vorticity within the TV, helping to reduce the overall flow fluctuations in the far field. These findings can be extended to explain the predominantly straight LE wing shape with a small amount of curvature only observed near the wing tip for flapping fliers with Re from 103 to 104.