bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface functionalization of 3D printed poly-ε-caprolactone by ultrashort laser mirostructuring and ZnO nanolayer deposition
Authors: Filipov E , Delibaltov D , Stefanov R , Blagoev B S , Avdeev G , Terziyska P , Stoykov R , Daskalova A 
Published: February 2024

Abstract
Due to its mechanical properties and good biocompatibility, polycaprolactone (PCL) is a promising material for bone tissue regeneration. However, a major limitation to its use remains the lack of inherent antimicrobial properties and its susceptibility to bacterial colonisation and biofilm formation. A potent strategy for overcoming such issues is surface functionalisation at micro and nano level, which can have a great impact on cell-surface interaction without affecting the integrity of the material. This study presents a novel methodology for surface modification of polymers combining ultrashort laser microstructuring and atomic layer deposition of ZnO. For this purpose, the surface of 3D printed PCL scaffolds was treated with a femtosecond laser (λ=800 nm; τ=75 fs) in order to develop parallel microchannels onto which ZnO nanolayers were further deposited. The presence of ZnO on the laser structured and unstructured scaffolds was detected by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX). Both methods confirmed the successful layering as EDX further highlighted a trend that ZnO built up substantially more at the bottom of the microchannels rather than at the top of them. The obtained results would allow proceeding to the next step of the study – investigating the antimicrobial effect of the developed interfaces.
Characterization and antibacterial activity of co-sputtered Cu-doped TiO2 coatings deposited on Ti6Al4V alloy
Authors: Nikolova M P , Ilievska I , Handzhiyski Y , Ivanova V , Apostolova M D 
Published: February 2024

Abstract
Copper has gained increased interest because of its important role in metabolism and antimicrobial activity. In this study, composite target material of Ti and Cu was used to deposit TiO2 coatings doped with copper on Ti6Al4V alloy. The aim was to examine the influence of the applied bias during the deposition of Cu-doped TiO2 coating by sputtering in a glow-discharge in a pure O2 atmosphere for a deposition time of 240 min. Different substrate values, selected from 0 to -150 V, were used in the process. The increase in bias voltage from -50 to - 150 V decreased the thickness of the oxide coatings and improved their adhesion to the substrate while increasing the Cu2O phase at the expense of a CuO phase decrease. Simultaneously, the increase in bias voltage decreased Cu content from about 32 wt% for the -50 V biased down to around 11 wt% for the -150 V biased specimens. The antimicrobial efficacy against E. coli estimated by direct contact experiments on the top of the uncoated (control) and coated Ti6Al4V alloy revealed about 94% inhibition for the -50V biased down to around 37% for the -150 V biased coatings as opposed to the control.
Study of bonding parameters with Al and Au wires on Pd and Ag coatings
Authors: Tomov R , Kolev G , Dobrikov G , Aleksandrova M 
Published: February 2024

Abstract
The process of electrical connection with gold and aluminium wires to palladium and silver electrodes is studied. Parameters of the wire bonding, such as bond force, ultrasonic power, bond time and temperature of the layers, controlled by heating the substrate are varied to explore the reliability of the bonds in terms of mechanical strength, electrical conductivity and interdiffusion of particles between the electrode and functional material at different bonding conditions. The importance of this study is due to the need of electrical connectivity at the stage of wiring and packaging of gas sensors with a novel organic nanomaterial (carbyne), requiring different types of electrodes – Ohmic or Schottky - according to the measurement principle and sensor architecture. Pd and Ag are identified as the most suitable for Ohmic and Schottky contacts, respectively, because of their favourable energy level alignment at the organic/metal interface. The chosen method for bonds testing is measurement of the pull force causing bond failure. The results show that Pd coating was bondable by Au wire, and Ag coating by Al wire, as well as Au on Pd bonds have 4 times higher strength. It is found that the bonding procedure doesn’t affect negatively on the Au/Pd/carbyne interface in terms of diffusion and redistribution of metal particles, but Al/Ag/carbyne is characterized by poor adhesion and the bonds are peeled-off. The results give new knowledge for the fabrication of advanced gas sensors and for the interaction of the carbyne with different metals, which will serve as a base for further optimization of the manufacturing technology toward their commercialization.
Optical control of coherent magneto-optical resonances in potassium
Authors: Tsvetkov S , Gateva S 
Published: February 2024

Abstract
The influence of Light Induced Atomic Desorption (LIAD) on the potassium D2 line magneto-optical resonances in uncoated buffer-gas optical cell is investigated. LIAD effect reduces the drawbacks of conventional heating for achieving high atomic density that is essential for many spectroscopy-based applications. Another feature of LIAD is the impact on the dwelling time of the atoms when colliding with the surface of the cell. In this work we investigate LIAD from point of view to distinguish the influence of LIAD on the atomic density from the dwelling time as well as to control and improve the parameters of magneto-optical resonances in potassium vapor. The results are interesting for development of new precise optical sensors and devices for various applications.
Characterization of the TJ-II stellarator plasma by means of reciprocating Langmuir probes
Authors: Ivanova P , Hasan E , Vasileva E , Dimitrova M , Voldiner I , McCarthy K J , Hidalgo C , Popov Tsv K 
Published: February 2024

Abstract
Experiments were conducted in deuterium plasma in the TJ-II stellarator by means of swept Langmuir probes mounted on reciprocating probes manipulators. The results were processed using the four-parameter fit, as well as the triple-probe and the first-derivative probe techniques. The parameters determined were the floating potential, the ion saturation current density, the electron temperature and density, and the plasma potential. The results were obtained for two plasma heating techniques – electron cyclotron resonance heating (ECRH) and neutral beam injection (NBI) heating. In the case of ECRH, employing the first-derivative probe technique resulted in finding that the electron-energy distribution function (EEDF) was not Maxwellian, but rather a bi-Maxwellian one with thermal (14-25 eV) and cold (4-5 eV) electrons. In comparison, during NBI heating we found a Maxwellian EEDF with the electron temperature being around 5 eV and slightly increasing in the confined plasma, but always remaining below 15 eV. We present a detailed analysis and discussion of the data for the plasma parameters as acquired by different techniques of using the reciprocating probe manipulator.
Mn3O4/Vulcan XC-72R composites: preparation, physicochemical characterization and electrochemical study for purification of organic contaminants
Authors: Tsacheva Ivelina , Gigova Adriana , Dimitrov Ognian , Dimitrova Mariela , Stefanov Stefan , Uzun Dzhamal 
Published: February 2024

Abstract
The microwave-assisted technique was applied to the preparation of composites from manganese(II) acetate and Carbon-supported (Vulcan XC-72R). Composites were prepared by chemical deposition of manganese(II) acetate nanoparticles onto Vulcan XC-72R carbon black (catalytic mass) using microwave irradiation. The new composites were physicochemically characterized by Energy-dispersive X-ray spectroscopy (EDX) with scanning electron microscopy (SEM), BET surface area, pore size distribution and X-ray diffraction (XRD). BET analysis of Mn3O4/Vulcan XC-72R composites obtained by alkali method has shown specific surface area of 1135 m2/g. Novel composites were electrochemically studied as catalysts for the remediation of organic contaminants in industrial waters. From novel catalytic mass, double-sided coated electrodes on a Nickel mesh conductor were made by pressing and heating at 250 °C. The prepared electrodes have geometric area of 2.5 cm2. The electrodes were fabricated and studied regarding the amount of catalyst and 35 % Teflonized Vulcan XC-72R. Electrochemical studies were carried out for phenol oxidation in an aqueous solution in model electrolyte: phenol solution 200 mg.L-1 and supporting electrolyte: 18 g.L-1 NaCl and 2.6 mg.L-1 Na2SO4.
Investigation of the thermal gradients formed during the process of cooling of WAAM built Al99.7 specimen
Authors: Ormanova M , Kotlarski G , Kaisheva D , Nikitin A , Ossenbrink R , Doynov N , Valkov S , Michailov V 
Published: February 2024

Abstract
This work presents a preliminary experiment used to determine the possibility of developing a thermal model used to predict the thermal gradients formed during the process of wire and arc additive manufacturing (WAAM). For this purpose, an Al99.7 specimen was built using gas metal arc welding (GMAW) in the cold arc pulse mode. The temperature of both the substrate and each consecutive layer was measured using thermocouples and infrared thermometers and the experimental data was used for the calibration of the developed thermal model. The obtained results can be used for the further development of the thermal model.
Data mining techniques for quality improvement of electron beam welding process
Authors: Kolev G , Asenova-Robinzonova A , Koleva L , Koleva E 
Published: February 2024

Abstract
Besides the fulfilment of the technological requirements for the geometry of the obtained welded joints by electron beam welding, there is a necessity to avoid the conditions, which more probably will lead to defect appearance. It is assumed that the appearance of defects is more probable under some regime conditions. For the modelling of the dependence of bivariate quality characteristics (such as the defect appearance) on the process parameters two different modelling approaches are applied and compared – logistic regression and neural networks. The implemented model-based approaches are compared and applied for the prediction of the defect appearance, depending on the variation of the electron beam process parameters.
Colorful image reconstruction from neuromorphic event cameras with biologically inspired deep color fusion neural networks
Authors: Cohen-Duwek Hadar , Tsur Elishai Ezra 
Published: February 2024

Abstract
Neuromorphic event-based cameras communicate transients in luminance instead of frames, providing visual information with a fine temporal resolution, high dynamic range and high signal-to-noise ratio. Enriching event data with color information allows for the reconstruction of colorful frame-like intensity maps, supporting improved performance and visually appealing results in various computer vision tasks. In this work, we simulated a biologically inspired color fusion system featuring a three-stage convolutional neural network for reconstructing color intensity maps from event data and sparse color cues. While current approaches for color fusion use full RGB frames in high resolution, our design uses event data and low-spatial and tonal-resolution quantized color cues, providing a high-performing small model for efficient colorful image reconstruction. The proposed model outperforms existing coloring schemes in terms of SSIM, LPIPS, PSNR, and CIEDE2000 metrics. We demonstrate that auxiliary limited color information can be used in conjunction with event data to successfully reconstruct both color and intensity frames, paving the way for more efficient hardware designs.
Agrivoltaic system design tools for managing trade-offs between energy production, crop productivity and water consumption
Authors: Warmann Emily , Jenerette G Darrel , Barron-Gafford Greg A 
Published: February 2024

Abstract
Agrivoltaic systems that locate crop production and photovoltaic energy generation on the same land have the potential to aid the transition to renewable energy by reducing the competition between food, habitat, and energy needs for land while reducing irrigation requirements. Experimental efforts to date have not adequately developed an understanding of the interaction among local climate, array design and crop selection sufficient to manage trade-offs in system design. This study simulates the energy production, crop productivity and water consumption impacts of agrivoltaic array design choices in arid and semi-arid environments in the Southwestern region of the United States. Using the Penman–Monteith evapotranspiration model, we predict agrivoltaics can reduce crop water consumption by 30%–40% of the array coverage level, depending on local climate. A crop model simulating productivity based on both light level and temperature identifies afternoon shading provided by agrivoltaic arrays as potentially beneficial for shade tolerant plants in hot, dry settings. At the locations considered, several designs and crop combinations exceed land equivalence ratio values of 2, indicating a doubling of the output per acre for the land resource. These results highlight key design axes for agrivoltaic systems and point to a decision support tool for their development.
Sea surface temperature driven modulation of decadal co-variability in mean and extreme precipitation
Authors: Adamu Mustapha , McGregor Shayne , Gallant Ailie J E 
Published: February 2024

Abstract
This study investigates the role that sea surface temperature (SST) variability plays in modulating the relationship between decadal-scale mean precipitation and monthly-scale extreme precipitation using the Australian Community Climate and Earth System Simulator Earth System model (ACCESS ESM1.5) climate model. The model large ensemble successfully reproduces the observed strong co-variability between monthly mean rainfall and wet extreme rainfall, defined as monthly rainfall totals above the 95th percentile. Removing SST variability in the ACCESS ESM1.5 model significantly weakens the co-variability between mean and wet extremes over most of the globe, showing that SSTs play a key role in modulating this co-variability. The study identifies Pacific and Atlantic SST patterns as the main drivers of the decadal scale co-variability in mean and extreme wet precipitation. On the other hand, observations and model results show that co-variability between mean and dry extremes is generally weaker than for wet extremes, with highly regional signals. Model experiments also show that SST variability plays a weaker role in modulating the co-variability between the mean precipitation and dry extremes as compared to wet extremes. These results suggest that stochastic atmospheric variability plays a stronger role in generating dry precipitation extremes compared SST forcing.
The impacts of shipping emissions on lightning: roles of aerosol-radiation-interactions and aerosol-cloud-interactions
Authors: Sun Ruize , Lu Xiao , Gao Meng , Du Yu , Lin Haipeng , Wright Chris , He Cheng , Yin Ke 
Published: February 2024

Abstract
Long-term (2005–2021) observations from the World Wide Lightning Location Network reveal significantly larger flash counts over heavily trafficked shipping lanes in the northeastern Indian Ocean compared to nearby regions. Here, we use the online coupled meteorology-chemistry model WRF-Chem to examine the impact of aerosols from shipping emissions on lightning activity over one of the world’s busiest shipping lanes (5–7° N, 82–92° E). We conduct three case simulations in January 2013, 2015, and 2018 when frequent lightning activities were recorded. The WRF-Chem model with lightning parameterized based on convective cloud-top height captures the temporal evolution of lightning activities but overestimates the magnitude of lightning counts. We find that all three cases consistently show enhanced lightning flash counts due to shipping-induced aerosols by 6.2%–22.3%, accompanied by increased cloud droplet number, cloud water concentration, radar reflectivity, and cloud-top height. Sensitivity simulations show that aerosol-cloud-interactions from shipping aerosols consistently enhance the strength of convection and lightning frequency in all three cases, by increasing cloud condensation nuclei and cloud droplet numbers, delaying precipitation of cloud water, allowing the lift and accumulation of water vapor, increasing release of latent heat, and finally invigorating convections. In comparison, aerosol-radiation-interactions show inconsistent contributions to convection and lightning, which enhance lightning frequency in the 2013 and 2015 cases but decrease lightning frequency in the 2018 case. This inconsistency may be attributed to differences in the number and vertical structure of shipping aerosols and cloud droplet in the three cases. Our study thus approves the certain but complicated anthropogenic impacts on lightning activities through shipping-induced aerosols, which has important implications for understanding future trends in lightning and its impact on atmospheric chemistry and climate.
Magnetic and electronic properties of anisotropic magnetite nanoparticles
Authors: Mitra Arijit , Mohapatra Jeotikanta , Aslam M 
Published: February 2024

Abstract
Magnetic materials at the nanometer scale can demonstrate highly tunable properties as a result of their reduced dimensionality. While significant advancements have been made in the production of magnetic oxide nanoparticles over the past decades, maintaining the magnetic and electronic phase stabilities in the nanoscale regime continues to pose a critical challenge. Finite-size effects modify or even eliminate the strongly correlated magnetic and electronic properties through strain effects, altering density and intrinsic electronic correlations. In this review, we examine the influence of nanoparticle size, shape, and composition on magnetic and tunneling magnetoresistance (TMR) properties, using magnetite (Fe3O4) as an example. The magnetic and TMR properties of Fe3O4 nanoparticles are strongly related to their size, shape, and synthesis process. Remarkably, faceted nanoparticles exhibit bulk-like magnetic and TMR properties even at ultra-small size-scale. Moreover, it is crucial to comprehend that TMR can be tailored or enhanced through chemical and/or structural modifications, enabling the creation of ‘artificially engineered’ magnetic materials for innovative spintronic applications.
The influence of NaOH concentration on the strength and microstructure of ceramic binders prepared from coal gangue through geopolymerization
Authors: Zhu Boheng , Yu Ruien , Shang Jinyu , Xi Xuanye , Liu Yao , Zhu Xijing 
Published: February 2024

Abstract
The efficient utilization of coal gangue plays an indispensable role in reducing environmental pressure, improving resource utilization efficiency and promoting green development. As a kind of solid waste rich in silicon and aluminium, coal gangue can be used to prepare ceramic materials. Therefore, a new ceramic preparation process was proposed in this study to prepare ceramic binders for grinding wheels by geopolymerization. The SiO2-B2O3-Al2O3-RO-R2O ceramic binder, a green and low-cost material, was successfully prepared using this method. The effect of the concentration of NaOH on the mechanical properties and microstructure of the ceramic binder was also studied. The strength and microstructure of different ceramic binders were characterized by XRD, TG-DTG, SEM-EDS and FT-IR. The results show that the bending strength of the geopolymer ceramic binder increases proportionately with the increase of NaOH concentration. When the concentration of sodium hydroxide is 15 M, the bending strength reaches 19 MPa. N-A-S-H gel and zeolite formed in the geopolymerization reaction and the pores formed in the sintering process have a significant effect on the bending strength of the ceramic binder. This technology can significantly stimulate the chemical activity of coal gangue and provide innovative ideas for efficient utilization of coal gangue.
Phase composition, surface chemistry and electrochemical studies of electrodeposited AlMnFeCuNi high entropy alloy composite coatings incorporated with carbon nanotubes
Authors: Mohan Mansha , Pandel Upender , Kumar Krishna 
Published: February 2024

Abstract
AlMnFeCuNi high entropy alloy (HEA) coatings were electrodeposited onto mild steel substrate with and without incorporation of carbon nano tubes (CNT). This paper focused on the morphology, hardness, wear and corrosion behaviour for as deposited HEA and HEA-CNT coatings. Both the coatings constituted simple solid solution with face-centered cubic (FCC) structure. The addition of carbon nano tubes in the HEA coatings as revealed by scanning electron microscopy showed more smaller granules and compact morphology with least coating thickness value (5 ± 0.35 μm). Enhanced Anti-wear performance results in higher hardness and lower coefficient of friction. The presence of CNTs resulted improvised corrosion resistant properties in 3.5% NaCl corrosive media. The formation of more protective oxides such as Alox
+3, Mnox
+2 and Feox
+3 on passive oxide layer in HEA-CNT coatings acted as a barrier, protected it from corrosion.
Two distinct declining trend of autumn Arctic sea ice concentration before and after 2002
Authors: Li Yijiao , Jiang Zhina , Yao Yao , Ding Minghu , Zhang Lei 
Published: February 2024

Abstract
This study investigates the Arctic sea ice concentration trend during 1979–2021 and explores why the autumn Arctic sea ice loss is accelerated after 2002 and its trend declining center shifts from the Chukchi Sea to the Barents-Kara-Laptev Seas. Attribution analysis reveals that the enhanced summer sea ice concentration negative trend in large part explains the autumn sea ice concentration accelerating reduction, whereas it is the trend center shift of increased downward longwave radiation that accounts for mostly of the autumn sea ice concentration decline center shift. Further analysis suggests the downward longwave radiation trend is closely related to large-scale atmospheric circulation changes. A tendency towards a dipole structure with an anticyclonic circulation over Greenland and the Arctic Ocean and a cyclonic circulation over Barents-Kara Seas enhances (suppresses) the downward longwave radiation over Western (Eastern) Arctic by warming and moistening (cooling and drying) the lower troposphere during 1979–2001. In comparison, a tendency towards a stronger Ural anticyclone combined with positive phase of the North Atlantic Oscillation pattern significantly promotes the increase of downward longwave radiation over Barents-Kara-Laptev Seas during 2002–2021. Our results set new insights into the Arctic sea ice variability and deepen our understanding of the climate change.