bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

AbstractWe 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

Abstract
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

Abstract
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

Abstract
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.
Karanjin-loaded soya lecithin-based ethosomal nanogel for the therapeutic intervention of psoriasis: formulation development, factorial design based-optimization, in vitro and in vivo assessment
Authors: Mujtaba Md Ali , Gangane Purushottam , Ali Abuzer , Chaudhari Shubham , Kaleem Mohammed , More Sachin , Shahzad Naiyer , Elhassan Gamal Osman , Anwer Md Khalid 
Published: July 2024

Abstract
This study aimed to develop and optimize karanjin-loaded ethosomal nanogel formulation and evaluate its efficacy in alleviating symptoms of psoriasis in an animal model induced by imiquimod. These karanjin-loaded ethosomal nanogel, were formulated to enhance drug penetration into the skin and its epidermal retention. Karanjin was taken to formulate ethosomes due to its potential ani-psoriatic activity. Ethosomes were formulated using the cold method using 32 full factorial designs to optimize the formulation components. 9 batches were prepared using two independent variables X
1: concentration of ethanol and X
2: concentration of phospholipid whereas vesicle size (Y
1) and percentage entrapment efficiency (Y
2) were selected as dependent variables. All the dependent variables were found to be statistically significant. The optimized ethosomal suspension (B3) exhibited a vesicle size of 334 ± 2.89 nm with an entrapment efficiency of 94.88 ± 1.24% and showed good stability. The morphology of vesicles appeared spherical with smooth surfaces through transmission electron microscopy analysis. X-ray diffraction analysis confirmed that the drug existed in an amorphous state within the ethosomal formulation. The optimized ethosome was incorporated into carbopol 934 to develop nanogel for easy application on the skin. The nanogel underwent characterization for various parameters including spreadability, viscosity, pH, extrudability, and percentage drug content. The ethosomal formulation remarkably enhanced the skin permeation of karanjin and increased epidermal retention of the drug in psoriatic skin compared to marketed preparation and pure drug. A skin retention study showed that ethosomal nanogel formulation has 48.33% epidermal retention in 6 h. In vivo, the anti-psoriatic activity of karanjin ethosomal nanogel demonstrated significant improvement in psoriasis, indicated by a gradual decrease in skin thickness and scaling as reflected in the Psoriasis Severity Index grading. Therefore, the prepared ethosomal nanogel is a potential vehicle for improved topical delivery of karanjin for better treatment of psoriasis.
Carbon dioxide removal and net zero emissions in Africa: an integrated assessment modelling based on three different land-based negative emission solutions
Authors: Ampah Jeffrey Dankwa , Afrane Sandylove , Adun Humphrey , Dioha Michael O , Agyekum Ephraim Bonah , Yusuf Abdulfatah Abdu , Naseer Mudassar , Bamisile Olusola 
Published: July 2024

Abstract
As the remaining carbon budget for limiting warming to 1.5 °C rapidly diminishes, it is clear that, besides decarbonization, the world will need to remove 100–1000 GtCO2 from the atmosphere by the end of the century. Yet, Africa, where many carbon removal schemes are planned, remains a ‘blindspot’ in existing studies. There is limited understanding of the trade-offs and synergies associated with carbon removal within Africa’s energy-land-water system. To address this research gap, we model a stylized net-zero emissions (NZEs) in Africa by 2050, with focus on three land-based biological carbon removal approaches: afforestation/reforestation (AR), bioenergy with carbon capture and storage (BECCS), and biochar. We find that by 2050, the total gross carbon removal is projected to reach 1.2 GtCO2 yr−1 when all three carbon removal approaches are available, and 0.5 GtCO2 yr−1 when Africa relies solely on AR. Pursuing NZE with only AR or AR alongside biochar in Africa would be the most expensive mitigation option but they lead to the lowest residual fossil fuel and industry CO2 emissions. An NZE by 2050 in Africa could reduce cropland by 30%–40% from 2020 to 2050, depending on the carbon dioxide removal deployment strategy adopted. Southern Africa would be particularly affected, facing significant challenges in balancing food security with climate goals. The highest increase in staple food prices will occur under AR only, while the availability of AR-BECCS-biochar produces the lowest rise in staple food prices. Our findings highlight the need for balanced and region-specific carbon dioxide removal strategies to ensure climate and other sustainability goals are met.
Coagulation-flocculation process on a lattice: Monte Carlo simulations
Authors: Blavatska Viktoria , Ilnytskyi Jaroslav , Lähderanta Erkki 
Published: July 2024

Abstract
Coagulation-flocculation, the physicochemical process widely used for purification a wastewater, is affected both by chemical details of involved polymers and by the statistics of their conformations on a large scale. The latter aspect is covered in this study by employing a coarse-grained modeling approach based on a combination of two paradigms of statistical mechanics. One is the self-avoiding walk (SAW) which generates a range of conformations for a linear polymer of N
SAW monomers. Another one is a non-trivial diffusion limited aggregation (DLA) process of N
DLA impurities (referred thereafter as ‘particles’) which describes their coagulation occurring with the probability

0
<
p
⩽
1

(p = 1 recovers a standard DLA). DLA of diffusive particles is complemented by their irreversible adsorption on the SAW monomers occurring with the probability equal to one, both processes resulting in formation of the DLA-SAW agglomerates. The dynamics of formation of such agglomerates, as well as their fractal dimensions and internal structure are of practical interest. We consider a range of related characteristics, such as: (i) absolute Na
and relative na
adsorbing efficiencies of SAW; (ii) effective gyration radius

R

g
DLA-SAW

of the DLA-SAW agglomerates; and (iii) the fractal dimension

D

DLA-SAW

of these aggregates. These are studied within a wide range for each parameter from a set

{
p
,

N

DLA

,

N

SAW

}

.