Gallium oxide(Ga_(2)O_(3))is an ultra-wide bandgap semiconductor with excellent potential for high-power and ultraviolet optoelectronic device applications.High-performance Ga_(2)O_(3)-based high-power devices rely he...Gallium oxide(Ga_(2)O_(3))is an ultra-wide bandgap semiconductor with excellent potential for high-power and ultraviolet optoelectronic device applications.High-performance Ga_(2)O_(3)-based high-power devices rely heavily on precise processing,especially in wafer dicing.Laser stealth dicing(LSD)is an innova-tive laser technology that utilizes a focused laser to create subsurface modifications in the wafer without surface damage.LSD has broad application prospects in the field of semiconductor precision processing.In this work,the idea of achieving high-quality dicing ofβ-Ga_(2)O_(3) wafers via LSD was proposed.A com-bination of atomistic simulations and experiments was used to understand the underlying mechanism of LSD ofβ-Ga_(2)O_(3) wafers.On the one hand,the laser loading and fracture process ofβ-Ga_(2)O_(3) wafers were simulated using molecular dynamics(MD)methods as well as a machine learning potential.The effects of single-pulse energy on LSD were analyzed through the lattice residual pressure,the final total energy of the system,the internal atomic strain,and the maximum stress value during uniaxial tension.On the other hand,based on the MD simulations,LSD was successfully performed onβ-Ga_(2)O_(3) wafers along three main crystal planes in the laboratory,resulting in good surface quality.This work not only provides profound optimization strategies for the LSD process ofβ-Ga_(2)O_(3),establishing the foundation for high-quality dicing ofβ-Ga_(2)O_(3) wafers,but also verifies the accuracy of MD simulations in predict-ing trends related to the LSD,offering a potential approach for high-quality dicing of other materials in future research.展开更多
Chemical vapor deposition(CVD)-grown diamond films have been developed as irradiation-resistant materials to replace or upgrade current detectors for use in extreme radiation environments. However, their sensitivity i...Chemical vapor deposition(CVD)-grown diamond films have been developed as irradiation-resistant materials to replace or upgrade current detectors for use in extreme radiation environments. However, their sensitivity in practical applications has been inhibited by space charge stability issues caused by defects and impurities in pure diamond crystal materials. In this study, two high-quality CVD-grown single-crystal diamond(SCD) detectors with low content of nitrogen impurities were fabricated and characterized. The intrinsic properties of the SCD samples were characterized using Raman spectroscopy, stereomicroscopy, and X-ray diffraction with the rocking curve mode, cathode luminescence(CL), and infrared and ultraviolet-visible-near infrared spectroscopies. After packaging the detectors, the dark current and energy resolution under α particle irradiation were investigated. Dark currents of less than 5 pA at 100 V were obtained after annealing the electrodes, which is comparable with the optimal value previously reported. The detector that uses a diamond film with higher nitrogen content showed poor energy resolution, whereas the detector with more dislocations showed poor charge collection efficiency(CCE). This demonstrates that the nitrogen content in diamond has a significant effect on the energy resolution of detectors, while the dislocations in diamond largely contribute to the poor CCE of detectors.展开更多
In this article, we report the results of our detailed investigations of the growth kinetics of zero-dimensional nanocrystals as well as one-dimensional nanorods by the combined use of small angel X-ray scattering （S...In this article, we report the results of our detailed investigations of the growth kinetics of zero-dimensional nanocrystals as well as one-dimensional nanorods by the combined use of small angel X-ray scattering （SAXS）, transmission electron microscopy （TEM） along with other physical techniques. The study includes growth kinetics of gold nanocrystals formed by the reduction of HAuCl4 by tetrakis（hydroxymethyl） phosphonium chloride in aqueous solution, of CdSe nanocrystals formed by the reaction of cadmium stearate and selenium under solvothermal conditions, and of ZnO nanorods formed by the reaction of zinc acetate with sodium hydroxide under solvothermal conditions in the absence and presence of capping agents. The growth of gold nanocrystals does not follow the diffusion-limited Ostwald ripening, and instead follows a Sigmoidal rate curve. The heat change associated with the growth determined by isothermal titration calorimetry is about 10 kcal·mol^-1 per I nm increase in the diameter of the nanocrystals. In the case of CdSe nanocrystals also, the growth mechanism deviates from diffusion-limited growth and follows a combined model containing both diffusion and surface reaction terms. Our study of the growth kinetics of uncapped and poly（vinyl pyrollidone） （PVP）-capped ZnO nanorods has yielded interesting insights. We observe small nanocrystals next to the ZnO nanorods after a lapse of time in addition to periodic focusing and defocusing of the width of the length distribution. These observations lend support to the diffusion-limited growth model for the growth of uncapped ZnO nanorods. Accordingly, the time dependence on the length of uncapped nanorods follows the L3 law as required for diffusion-limited Ostwald ripening. The PVP-capped nanorods, however, show a time dependence, which is best described by a combination of diffusion （L^3） and surface reaction （L^2） terms.展开更多
To improve the industrialization of the process,the study of a thixoforming line stability was proposed.The thixoforming line is fully automated to optimize the repeatability of the experiments.Parameters of the heati...To improve the industrialization of the process,the study of a thixoforming line stability was proposed.The thixoforming line is fully automated to optimize the repeatability of the experiments.Parameters of the heating cycle,the slug temperature,the tool temperature and the forming speed were studied.For each of them,a range of the expected variations in a steady-state process as well as the effects of these variations on the process itself(forming load and parts quality) were given.These variations are shown to be acceptable.Three different tools were used in the experiments.Some mathematical simulations were realized on the finite elements code Forge2008with a semi-solid constitutive law.The capacity of the model to represent the process stability was discussed.The simulation results are in agreement with the experiment results.展开更多
This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients （TECs）, when zirconia ceramics were coloured at green stage. Z...This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients （TECs）, when zirconia ceramics were coloured at green stage. Zirconia blocks （N=240; 6 mm x 7 mm x 7 mm） were manufactured from two materials namely, ICE Zirconia （Group 1） and Prettau Zirconia （Group 2）. In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid （shade A2）, Three different veneering ceramics with different TEC （ICE Ceramic, GC Initial Zr and IPS e.max Ceram） were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys （Esteticor Plus） veneered with ceramic （VM 13） （n= 16） acted as the control group. Core-veneer interface of the specimens were subjected to shear force in the Universal Testing Machine （0.5 mm-min-1）. Neither the zirconia core material （P=0.318） nor colouring （P=0.188） significantly affected the results （three-way analysis of variance, Tukey＇s test）. But the results were significantly affected by the veneering ceramic （P=0.000）. Control group exhibited significantly higher mean bond strength values （45.7__.8） MPa than all other tested groups （（27.1__.4.1）-（39.7__.4.7） and （27.4__.5.6）-（35.9___4.7） MPa with and without colouring, respectively） （P^0.001）. While in zirconia-veneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering ~ 1/3 of the substrate surface, in the metal-ceramic group, veneering ceramic was left adhered 1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core-veneer adhesion. Metal-ceramic adhesion was more reliable than all zirconia-veneer ceramics tested.展开更多
The characteristics of the LB films of Schiff base aluminium(Ⅲ), tris(2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium(Ⅲ)[Al(TA12)_3], were studied. The surface pressure-area(π-A) isotherm of Al(TA12)_3 in...The characteristics of the LB films of Schiff base aluminium(Ⅲ), tris(2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium(Ⅲ)[Al(TA12)_3], were studied. The surface pressure-area(π-A) isotherm of Al(TA12)_3 in the pure water subphase was investigated. The molecular area, 0.48 nm^2, is one-third of the expected value that indicates the formation of an aggregate. The Langmuir-Blodgett(LB) films of Al(TA12)_3 were transferred and characterized. The UV-Vis spectra and the AFM image both confirmed that the J-aggregates formed. The polarized UV-Vis spectra indicated that the complex plane had to be oriented with an angle of about 30° to the substrate surface. The IR spectra suggested that the complexation took place between aluminium ions and the oxygen atoms of the ligand rather than the nitrogen atom.展开更多
The surface pressure-area (pi -A) isotherm of Schiff base aluminium (III), tris (2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium (III) (denoted as Al(TAl2)(3)), on pure water subphase was investigated. The m...The surface pressure-area (pi -A) isotherm of Schiff base aluminium (III), tris (2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium (III) (denoted as Al(TAl2)(3)), on pure water subphase was investigated. The molecular area, 0.48 nm(2), is one-third of expected value that indicated the aggregation took place. The Langmuir-Blodgett (LB) films of Al(TAl2), was transferred and characterized. The AFM image confirmed the formation of aggregates.展开更多
This work describes the development of a process to produce zeolite X from mined kaolin clay from Kono-Boue and Chokocho, Rivers State, Nigeria. The procedures involved the beneficiation of the raw kaolin and calcinat...This work describes the development of a process to produce zeolite X from mined kaolin clay from Kono-Boue and Chokocho, Rivers State, Nigeria. The procedures involved the beneficiation of the raw kaolin and calcinations at 850<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C, to transform the kaolin to a more reactive metakaolin. Afterwards, the extremely reactive metakaolin was purge with sulphuric acid to obtain the much needed silica-alumina ratio for zeolite X synthesis. An alkaline fusion stage was then carried out to transform the metakaolin into zeolite by mixing with aqueous NaOH to form gel then allowed to stay for a duration of seven days at room temperature. The samples were then charged into a propylene container and placed in an oven at a temperature of 100<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C for the reaction to take place for 6 h. Identification of the crystalline phases by X-ray Diffraction (XRD), chemical/elemental compositions by X-ray Fluorescence (XRF)/Energy Dispersive Spectroscopic analyses (EDS), surface morphology by Scanning Electron Microscopy (SEM) and molecular vibration of units by Fourier Transform Infrared Spectrophotometry (FT-IR) were done. The results showed that the zeolite synthesized from Chokocho kaolin (CK) was more crystalline/larger with sharper peaks on both XRD and FTIR than that from Kono-Boue. This was also supported by slightly rougher surface morphology of CK over KK on SEM. XRF Si:Al ratios of 10.73 and 14.36 were obtained for KK and CK respectively. EDS results supported the XRF ratios. Sharper zeolitic characteristic O-H stretching bands at 3488 and 3755 cm<sup>-1</sup> were recorded for CK than KK. However, both results showed that zeolite X have been produced from both Kono-Boue and Chokocho kaolin clays respectively.展开更多
A simple layer-by-layer deposition technique was used to fabricate the multilayer thin films of unmodified silver triangular nanoplates （AgTNPs）. The multilayer of AgTNPs thin films were fabricated by alternate depo...A simple layer-by-layer deposition technique was used to fabricate the multilayer thin films of unmodified silver triangular nanoplates （AgTNPs）. The multilayer of AgTNPs thin films were fabricated by alternate deposition of each anionic sodium citrate stabilized AgTNPs and cationic poly（diallyldimethylammonium chloride）. All prepared AgTNPs multilayer thin films were exhibited a strong plasmon band at the wavelength of 667 rim, which confirmed the formation of AgTNPs onto the substrate. The characteristics of the multilayer thin films were investigated using contact angle measurement, UV-visible spectroscopy, X-ray diffraction analysis （XRD）, atomic force microscope （AFM） and field emission scanning electron microscope （FESEM）. As these films are to be used as a mercury （Ⅱ） colorimetric sensor, the changes in optical properties of the films were evaluated for various mercury （Ⅱ） concentrations. AgTNPs assembled into thin films showed a strong color shift from blue to mauve and colorless when exposed to mercury （Ⅱ）. The constructed multilayer thin films exhibited excellent color changes of mercury （Ⅱ） with a linear range between 0.5 and 20 ppm. The limit of detection （LOD） and limit of quantitation （LOQ） were 0.45 ± 0.002 and 1.52 - 0.002 ppm, respectively. The recovery values of AgTNPs multilayer thin films are satisfactory in the range of 100.1%-106.4% when applied to determining mercury （Ⅱ） in water samt）les.展开更多
A low-molecular-weight polylactide-poly(butylene succinate)(PLA-PBS)copolymer was synthesized and incorporated into polylactide(PLA)as a novel toughening agent by solvent casting.The copolymer had the same chemical st...A low-molecular-weight polylactide-poly(butylene succinate)(PLA-PBS)copolymer was synthesized and incorporated into polylactide(PLA)as a novel toughening agent by solvent casting.The copolymer had the same chemical structure and function as PLA and it was used as a plasticizer to PLA.The copolymer was blended with PLA at a weight ratio from 2 to 10 wt%.Phase separation between PLA and PLA-PBS was not observed from their scanning electron microscopy(SEM)images and the crystal structure of PLA almost remained unchanged based on the X-ray diffraction(XRD)measurement.The melt flow index(MFI)of the blends was higher as the amount of PLA-PBS increased,indicating that the block copolymer did improve the mobility of the PLA chains.Moreover,tensile tests revealed that PLA with greater PLA-PBS copolymer exhibited higher elongation at break and it reached the maximum at 8 wt%of PLA-PBS in PLA,which was around 6 times higher than that of pure PLA.Furthermore,the glass transition temperature,measured by differential scanning calorimetry(DSC),markedly decreased with an increasing amount of the copolymer as it decreased from 61.2℃ for pure PLA to 41.3℃when it was blended with 10 wt%PLA-PBS copolymer.Therefore,the PLA-PBS copolymer was shown to be a promising plasticizer for fully biobased and toughened PLA.展开更多
Nonlinear shock wave structures in unmagnetized collisionless viscous plasmas composed fluid of positive(negative) ions and nonthermally electron distribution are examined. For ion shock formation, a reductive perturb...Nonlinear shock wave structures in unmagnetized collisionless viscous plasmas composed fluid of positive(negative) ions and nonthermally electron distribution are examined. For ion shock formation, a reductive perturbation technique applied to derive Burgers equation for lowest-order potential. As the shock amplitude decreasing or enlarging,its steepness and velocity deviate from Burger equation. Burgers type equation with higher order dissipation must be obtained to avoid this deviation. Solution for the compined two equations has been derived using renormalization analysis. Effects of higher-order, positive- negative mass ratio Q, electron nonthermal parameter δ and kinematic viscosities coefficient of positive(negative) ions η1 and η2 on the electrostatic shocks in Earth's ionosphere are also argued.展开更多
In the last decade,North Africa has witnessed significant population growth,particularly those bordering the Mediterranean Sea.This led to increased demand for groundwater,which is an essential source for various wate...In the last decade,North Africa has witnessed significant population growth,particularly those bordering the Mediterranean Sea.This led to increased demand for groundwater,which is an essential source for various water uses such as drinking water supplies and irrigation.Generally,human activities play a crucial role in the different quantitative and qualitative changes in groundwater.Now,climate changes such as a decrease in precipitation have also led to a shortage of water resources and a decline in the groundwater table.This paper presents the impact of climate changes on groundwater resources in the Ain Azel region,Setif,northeastern Algeria.The analysis of longterm spatiotemporal variability in rainfall over 63 years(1958–2021)revealed a significant decline in groundwater recharge,especially after 2013.In contrast,the Pettitt and Mann–Kendall tests show increased temperatures with breaks between 1984 and 1986.A piezometric analysis of the alluvial aquifer demonstrated a significant decline in groundwater levels in the last 20 years.Hydrochemical analysis showed that groundwater in the region is dominated by Ca–Mg–Cl water type,which indicates the presence of water salinity phenomenon.Water Quality Index(WQI)analysis showed the deterioration of groundwater in the area,which may be caused by several factors:brine intrusion from the Salt Lake(Sebkha)in the north;the dissolution of evaporites(Triassic)and/or anthropogenic sources of agricultural and industrial origin.Our findings provide an overview summarizing the state of groundwater,which will help improve groundwater resource management in the region in the coming years.展开更多
In low carbon steels, dissolution and precipitation of the second phases such as carbides and nitrides during annealing cycles can affect the final structure and properties of the materials. The interaction of above p...In low carbon steels, dissolution and precipitation of the second phases such as carbides and nitrides during annealing cycles can affect the final structure and properties of the materials. The interaction of above processes depends on parameters such as reheating temperature, heating rate, annealing temperature, soaking time and finishing temperature in hot rolling stage before cold rolling. The effects of heating rate and annealing temperature on the microstructure and hardness were investigated. Two heating rates for annealing temperatures of 550, 610 and 720℃ were applied on cold-rolled specimens and St-14 low carbon steel, which were immediately quenched after isothermal annealing. The intercept method was used tO measure average grain sizes. However, resulted microstructures are dif- ferent for the two heating rates. While pancaked structures were observed in specimens annealed with low heating rate, in samples annealed with high heating rate, equiaxed microstructures were observed. Vickers micro-hardness values decreased at all temperatures, which were more significant at higher temperatures. At longer annealing time, signs of increase of hardness values were detected. All results and observations consistently suggest that a precipitati- on process has occurred concurrently with restoration processes during annealing. In addition, the energy dispersive spectroscopy analysis resulted from transmission electron microscopic micrographs have proved that the nano particles precipitated in grain boundaries are AlN.展开更多
In the present study, multiwalled carbon nanotubes（MWCNTs）, gold nanoparticles（AuN Ps）, and glutathione（GSH） were used to fabricate multilayer nanoscale thin films. The composite thin films were fabricated by la...In the present study, multiwalled carbon nanotubes（MWCNTs）, gold nanoparticles（AuN Ps）, and glutathione（GSH） were used to fabricate multilayer nanoscale thin films. The composite thin films were fabricated by layer-by-layer technique as the films were constructed by the alternate deposition of cationic and anionic polyelectrolytes. The MWCNTs were modified via a noncovalent surface modification method using poly（diallydimethylammonium chloride） to form a cationic polyelectrolyte. An anionic polyelectrolyte was prepared by the chemical reduction of HAuCl_4 using sodium citrate as both the stabilizing and reducing agent to form anionic AuN Ps. GSH was used as an electrocatalyst toward the electro-oxidation of dopamine. The constructed composite electrode exhibits excellent electrocatalytic activity toward dopamine with a short response time and a wide linear range from 1 to 100 mmol/L. The limits of detection and quantitation of dopamine are（0.316 ± 0.081） mmol/L and（1.054 ± 0.081） mmol/L, respectively. The method is satisfactorily applied for the determination of dopamine in plasma and urine samples to obtain the recovery in the range from 97.90% to 105.00%.展开更多
Combinations of metal and lanthanide oxides have been done through casted films for potential medical applications. In this regard, samarium(Ⅲ) oxide/chromium(Ⅲ) oxide/graphene oxide(GO)/polycaprolactone(PCL) based ...Combinations of metal and lanthanide oxides have been done through casted films for potential medical applications. In this regard, samarium(Ⅲ) oxide/chromium(Ⅲ) oxide/graphene oxide(GO)/polycaprolactone(PCL) based films nano-composites(NCs) were fabricated, pointing their utilization as a biological scaffold for wound dressing purposes. Also, samarium(Ⅲ) oxide and chromium(Ⅲ) oxide have been merged as promising optical constituents due to their unique optical behavior. The structural and compositional examination of the studied NCs was executed by X-ray diffraction(XRD), Raman, and field emission scanning electron microscopy(FESEM). The Sm_(2)O_(3)/Cr_(2)O_(3)/GO/PCL NC exhibits a surface with a lower roughness degree owing to the presence of GO. Cr_(2)O_(3)shows size reduction upon GO insertion to reach 1.2 μm as the average grain size, whilst Sm_(2)O_(3)records an average grain size of less than 1 μm. As well, the polymeric nano-compositions exhibit variation in contact angle values that hit 29.76°± 3.52°for Sm_(2)O_(3)/PCL, and 48.62°± 1.37°for Sm_(2)O_(3)/Cr_(2)O_(3)/GO/PCL as the second lowest contact angle. The optical behavior contributes to absorption edge relocation along the x-axis from 1.7 eV for pure PCL, to 2.65 eV for Sm_(2)O_(3)/Cr_(2)O_(3)/GO/PCL. Regarding biological responses, the cell exposed to 2.5 μg/m L of Sm_(2)O_(3)/Cr_(2)O_(3)/GO/PCL shows cell viability of 119.31%, while 5 μg/m L hits 99.6%. Additionally, the resulting cell attachment micrographs show layers of fibroblast tissue, besides the proliferation and growth of cultivated cells. Thus, the Sm_(2)O_(3)/Cr_(2)O_(3)/GO/PCL scaffold provides 3D proliferation of fibroblast cells endorsing the wound healing process.展开更多
Developing a biomaterial for wound healing applications is still a challenge.Herein,dysprosium oxide(Dy_(2)O_(3)),aluminum oxide(Al_(2)O_(3)),and graphene oxide(GO)were embedded in cast films based on polycaprolactone...Developing a biomaterial for wound healing applications is still a challenge.Herein,dysprosium oxide(Dy_(2)O_(3)),aluminum oxide(Al_(2)O_(3)),and graphene oxide(GO)were embedded in cast films based on polycaprolactone(PCL)to be examined for wound dressing usage.Different techniques were used to characterize the fabricated films including X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),Raman,and scanning electron microscopy(SEM),besides their biological activity.The thermogravimetric analysis(TGA)exhibits high thermal stability as the scaffold weight decreases slightly to 98.6%after raising the temperature from room temperature to 280℃.The cell viability was investigated and it is shown that the viable cells grow up to approximately 93%at 75μg/mL.Meanwhile,the cell attachment shows excellent behavior as the cells attach on most of the surface of the modified PCL which shows high biocompatibility.展开更多
The tribovoltaic nanogenerator(TVNG)has evolved in recent years as a novel type of nanogenerator designed to address the limitations of the standard triboelectric nanogenerator in terms of output signal and charge gen...The tribovoltaic nanogenerator(TVNG)has evolved in recent years as a novel type of nanogenerator designed to address the limitations of the standard triboelectric nanogenerator in terms of output signal and charge generation.Besides the outstanding characteristics,the tribovoltaic effect can also well be coupled with another effect to further boost the output performance.In this work,we proposed firstly a frictional heat-assisted performance enhancement in dynamic Schottky contact from the rubbing between n-type silver selenide(Ag_(2)Se)and aluminum.The chemical composition and physical characteristics of the Ag_(2)Se ceramic were analyzed using X-ray diffraction,scanning electron microscopy,and Synchrotron X-ray tomography techniques.UVeVis spectroscopy and UPS were also utilized in order to validate the semiconducting property of the n-type Ag_(2)Se ceramic.Moreover,the presence of the Schottky junction was demonstrated through the analysis of the current-bias voltage characteristic curve of the Ag_(2)Se/aluminum(Al)contact under varying stress and temperature conditions.The built-in electric field plays a crucial part in the tribovoltaic effect by efficiently transferring the excited carriers to an external load through sliding contact between Ag_(2)Se and Al.Demonstrating the synergy between tribovoltaic and thermoelectric effects becomes achievable through the excellent thermoelectric property of Ag_(2)Se.Herein,the proposed TVNG generated a peak output voltage and current of around 0.7 V and 24.8 nA,respectively,achieving a maximum output power of 12.6 nW at a load resistance of 10 kU.The influence of frictional heat on the output performance of the proposed TVNG was well demonstrated by the thermal-induced voltage and enhanced electrical output from continuous sliding.The concepts given in this study establish the basis for the progress of effective energy collection employing semiconducting materials and the advancement of flexible harvesting and sensing device development in the future.展开更多
High quantum yield carbon dot(CD)was synthesized from water hyacinth leaves(WH)through ionizing gamma radiation,eliminating the need for heat or chemical treatments.The study investigated the effects of different gamm...High quantum yield carbon dot(CD)was synthesized from water hyacinth leaves(WH)through ionizing gamma radiation,eliminating the need for heat or chemical treatments.The study investigated the effects of different gamma doses(50,100,150 kGy)on the resulting CD’s optical properties,particle sizes,and surface chemistry.The 50 kGy dose produced CD(CD50)with a remarkable quantum yield of 48.3%.Polyvinyl alcohol(PVA)-CD50 composite films demonstrated enhanced root growth in Chinese convolvulus by 19%and were non-toxic to human cells.These composites also proved effective for food packaging applications,as evidenced by the reduced color changes in strawberries under UV light exposure.This study introduces a green synthesis approach for transforming invasive water hyacinth into a high-value CD,with promising applications in electronics,catalysis,and sensing.展开更多
Bipolar electrochemistry is a high-throughput corrosion testing method capable of applying a quasi-linear potential gradient across test specimens.This study employs-bipolar electrochemistry corrosion testing to inves...Bipolar electrochemistry is a high-throughput corrosion testing method capable of applying a quasi-linear potential gradient across test specimens.This study employs-bipolar electrochemistry corrosion testing to investigate the influence of gravity on pitting corrosion of type 304L and 420 stainless steel across a broad range of applied potentials.Gravity modifies the distribution of current density on the bipolar electrode without altering the potential distribution.The impact of gravity on pitting corrosion is achieved through its effects on the dilution of the electrolyte and the removal of the salt film within the pits.Pits oriented in a face up position demonstrate smoother morphologies,larger cross-sectional areas and pit volumes.In contrast,pits oriented in perpendicular and facedown positions exhibit pit shape.Under conditions governed by diffusion and activation control,pits can up to over 100μm.Additionally,crystallographic pits are observed to form in areas subjected to high applied potentials.展开更多
基金financially supported by the National Nat-ural Science Foundation of China(Nos.92473102,62004141,and 52202045)the Knowledge Innovation Program of Wuhan-Shuguang(Nos.2023010201020243,and 2023010201020255)+4 种基金the Major Program(JD)of Hubei Province(No.2023BAA009)the Shenzhen Science and Technology Program(No.JCYJ20240813175906008)the Fundamental Research Funds for the Central Universities(Nos.2042023kf0112,and 2042022kf1028)the Open Fund of Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration(Wuhan University)(Nos.EMPI2024014,EMPI2024021,and EMPI2023027)the China Scholarship Council(No.202206275005).
文摘Gallium oxide(Ga_(2)O_(3))is an ultra-wide bandgap semiconductor with excellent potential for high-power and ultraviolet optoelectronic device applications.High-performance Ga_(2)O_(3)-based high-power devices rely heavily on precise processing,especially in wafer dicing.Laser stealth dicing(LSD)is an innova-tive laser technology that utilizes a focused laser to create subsurface modifications in the wafer without surface damage.LSD has broad application prospects in the field of semiconductor precision processing.In this work,the idea of achieving high-quality dicing ofβ-Ga_(2)O_(3) wafers via LSD was proposed.A com-bination of atomistic simulations and experiments was used to understand the underlying mechanism of LSD ofβ-Ga_(2)O_(3) wafers.On the one hand,the laser loading and fracture process ofβ-Ga_(2)O_(3) wafers were simulated using molecular dynamics(MD)methods as well as a machine learning potential.The effects of single-pulse energy on LSD were analyzed through the lattice residual pressure,the final total energy of the system,the internal atomic strain,and the maximum stress value during uniaxial tension.On the other hand,based on the MD simulations,LSD was successfully performed onβ-Ga_(2)O_(3) wafers along three main crystal planes in the laboratory,resulting in good surface quality.This work not only provides profound optimization strategies for the LSD process ofβ-Ga_(2)O_(3),establishing the foundation for high-quality dicing ofβ-Ga_(2)O_(3) wafers,but also verifies the accuracy of MD simulations in predict-ing trends related to the LSD,offering a potential approach for high-quality dicing of other materials in future research.
基金This work was financially supported by the Natural Science Foundation of Beijing,China(No.4192038)National Key Research and Development Program of China(Nos.2016YFE0133200 and 2018YFB0406501)European Union’s Horizon 2020 Research and Innovation Staff Exchange Scheme(No.734578).
文摘Chemical vapor deposition(CVD)-grown diamond films have been developed as irradiation-resistant materials to replace or upgrade current detectors for use in extreme radiation environments. However, their sensitivity in practical applications has been inhibited by space charge stability issues caused by defects and impurities in pure diamond crystal materials. In this study, two high-quality CVD-grown single-crystal diamond(SCD) detectors with low content of nitrogen impurities were fabricated and characterized. The intrinsic properties of the SCD samples were characterized using Raman spectroscopy, stereomicroscopy, and X-ray diffraction with the rocking curve mode, cathode luminescence(CL), and infrared and ultraviolet-visible-near infrared spectroscopies. After packaging the detectors, the dark current and energy resolution under α particle irradiation were investigated. Dark currents of less than 5 pA at 100 V were obtained after annealing the electrodes, which is comparable with the optimal value previously reported. The detector that uses a diamond film with higher nitrogen content showed poor energy resolution, whereas the detector with more dislocations showed poor charge collection efficiency(CCE). This demonstrates that the nitrogen content in diamond has a significant effect on the energy resolution of detectors, while the dislocations in diamond largely contribute to the poor CCE of detectors.
文摘In this article, we report the results of our detailed investigations of the growth kinetics of zero-dimensional nanocrystals as well as one-dimensional nanorods by the combined use of small angel X-ray scattering （SAXS）, transmission electron microscopy （TEM） along with other physical techniques. The study includes growth kinetics of gold nanocrystals formed by the reduction of HAuCl4 by tetrakis（hydroxymethyl） phosphonium chloride in aqueous solution, of CdSe nanocrystals formed by the reaction of cadmium stearate and selenium under solvothermal conditions, and of ZnO nanorods formed by the reaction of zinc acetate with sodium hydroxide under solvothermal conditions in the absence and presence of capping agents. The growth of gold nanocrystals does not follow the diffusion-limited Ostwald ripening, and instead follows a Sigmoidal rate curve. The heat change associated with the growth determined by isothermal titration calorimetry is about 10 kcal·mol^-1 per I nm increase in the diameter of the nanocrystals. In the case of CdSe nanocrystals also, the growth mechanism deviates from diffusion-limited growth and follows a combined model containing both diffusion and surface reaction terms. Our study of the growth kinetics of uncapped and poly（vinyl pyrollidone） （PVP）-capped ZnO nanorods has yielded interesting insights. We observe small nanocrystals next to the ZnO nanorods after a lapse of time in addition to periodic focusing and defocusing of the width of the length distribution. These observations lend support to the diffusion-limited growth model for the growth of uncapped ZnO nanorods. Accordingly, the time dependence on the length of uncapped nanorods follows the L3 law as required for diffusion-limited Ostwald ripening. The PVP-capped nanorods, however, show a time dependence, which is best described by a combination of diffusion （L^3） and surface reaction （L^2） terms.
基金Project (415814) supported by the FIRST Europe,THIXOFROR
文摘To improve the industrialization of the process,the study of a thixoforming line stability was proposed.The thixoforming line is fully automated to optimize the repeatability of the experiments.Parameters of the heating cycle,the slug temperature,the tool temperature and the forming speed were studied.For each of them,a range of the expected variations in a steady-state process as well as the effects of these variations on the process itself(forming load and parts quality) were given.These variations are shown to be acceptable.Three different tools were used in the experiments.Some mathematical simulations were realized on the finite elements code Forge2008with a semi-solid constitutive law.The capacity of the model to represent the process stability was discussed.The simulation results are in agreement with the experiment results.
文摘This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients （TECs）, when zirconia ceramics were coloured at green stage. Zirconia blocks （N=240; 6 mm x 7 mm x 7 mm） were manufactured from two materials namely, ICE Zirconia （Group 1） and Prettau Zirconia （Group 2）. In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid （shade A2）, Three different veneering ceramics with different TEC （ICE Ceramic, GC Initial Zr and IPS e.max Ceram） were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys （Esteticor Plus） veneered with ceramic （VM 13） （n= 16） acted as the control group. Core-veneer interface of the specimens were subjected to shear force in the Universal Testing Machine （0.5 mm-min-1）. Neither the zirconia core material （P=0.318） nor colouring （P=0.188） significantly affected the results （three-way analysis of variance, Tukey＇s test）. But the results were significantly affected by the veneering ceramic （P=0.000）. Control group exhibited significantly higher mean bond strength values （45.7__.8） MPa than all other tested groups （（27.1__.4.1）-（39.7__.4.7） and （27.4__.5.6）-（35.9___4.7） MPa with and without colouring, respectively） （P^0.001）. While in zirconia-veneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering ~ 1/3 of the substrate surface, in the metal-ceramic group, veneering ceramic was left adhered 1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core-veneer adhesion. Metal-ceramic adhesion was more reliable than all zirconia-veneer ceramics tested.
基金Supported by the National Natural Science Foundation of China(No. 29973026, 20073016).
文摘The characteristics of the LB films of Schiff base aluminium(Ⅲ), tris(2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium(Ⅲ)[Al(TA12)_3], were studied. The surface pressure-area(π-A) isotherm of Al(TA12)_3 in the pure water subphase was investigated. The molecular area, 0.48 nm^2, is one-third of the expected value that indicates the formation of an aggregate. The Langmuir-Blodgett(LB) films of Al(TA12)_3 were transferred and characterized. The UV-Vis spectra and the AFM image both confirmed that the J-aggregates formed. The polarized UV-Vis spectra indicated that the complex plane had to be oriented with an angle of about 30° to the substrate surface. The IR spectra suggested that the complexation took place between aluminium ions and the oxygen atoms of the ligand rather than the nitrogen atom.
基金the NSFC (29973026, 29773017) and Beijing Natural Science Foundation (2992007) for the provision of financial support.
文摘The surface pressure-area (pi -A) isotherm of Schiff base aluminium (III), tris (2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium (III) (denoted as Al(TAl2)(3)), on pure water subphase was investigated. The molecular area, 0.48 nm(2), is one-third of expected value that indicated the aggregation took place. The Langmuir-Blodgett (LB) films of Al(TAl2), was transferred and characterized. The AFM image confirmed the formation of aggregates.
文摘This work describes the development of a process to produce zeolite X from mined kaolin clay from Kono-Boue and Chokocho, Rivers State, Nigeria. The procedures involved the beneficiation of the raw kaolin and calcinations at 850<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C, to transform the kaolin to a more reactive metakaolin. Afterwards, the extremely reactive metakaolin was purge with sulphuric acid to obtain the much needed silica-alumina ratio for zeolite X synthesis. An alkaline fusion stage was then carried out to transform the metakaolin into zeolite by mixing with aqueous NaOH to form gel then allowed to stay for a duration of seven days at room temperature. The samples were then charged into a propylene container and placed in an oven at a temperature of 100<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C for the reaction to take place for 6 h. Identification of the crystalline phases by X-ray Diffraction (XRD), chemical/elemental compositions by X-ray Fluorescence (XRF)/Energy Dispersive Spectroscopic analyses (EDS), surface morphology by Scanning Electron Microscopy (SEM) and molecular vibration of units by Fourier Transform Infrared Spectrophotometry (FT-IR) were done. The results showed that the zeolite synthesized from Chokocho kaolin (CK) was more crystalline/larger with sharper peaks on both XRD and FTIR than that from Kono-Boue. This was also supported by slightly rougher surface morphology of CK over KK on SEM. XRF Si:Al ratios of 10.73 and 14.36 were obtained for KK and CK respectively. EDS results supported the XRF ratios. Sharper zeolitic characteristic O-H stretching bands at 3488 and 3755 cm<sup>-1</sup> were recorded for CK than KK. However, both results showed that zeolite X have been produced from both Kono-Boue and Chokocho kaolin clays respectively.
基金supported by Faculty of Science,King Mongkut's Institute of Technology Ladkrabang,Bangkok,Thailand(No.2559-01-05-033)
文摘A simple layer-by-layer deposition technique was used to fabricate the multilayer thin films of unmodified silver triangular nanoplates （AgTNPs）. The multilayer of AgTNPs thin films were fabricated by alternate deposition of each anionic sodium citrate stabilized AgTNPs and cationic poly（diallyldimethylammonium chloride）. All prepared AgTNPs multilayer thin films were exhibited a strong plasmon band at the wavelength of 667 rim, which confirmed the formation of AgTNPs onto the substrate. The characteristics of the multilayer thin films were investigated using contact angle measurement, UV-visible spectroscopy, X-ray diffraction analysis （XRD）, atomic force microscope （AFM） and field emission scanning electron microscope （FESEM）. As these films are to be used as a mercury （Ⅱ） colorimetric sensor, the changes in optical properties of the films were evaluated for various mercury （Ⅱ） concentrations. AgTNPs assembled into thin films showed a strong color shift from blue to mauve and colorless when exposed to mercury （Ⅱ）. The constructed multilayer thin films exhibited excellent color changes of mercury （Ⅱ） with a linear range between 0.5 and 20 ppm. The limit of detection （LOD） and limit of quantitation （LOQ） were 0.45 ± 0.002 and 1.52 - 0.002 ppm, respectively. The recovery values of AgTNPs multilayer thin films are satisfactory in the range of 100.1%-106.4% when applied to determining mercury （Ⅱ） in water samt）les.
文摘A low-molecular-weight polylactide-poly(butylene succinate)(PLA-PBS)copolymer was synthesized and incorporated into polylactide(PLA)as a novel toughening agent by solvent casting.The copolymer had the same chemical structure and function as PLA and it was used as a plasticizer to PLA.The copolymer was blended with PLA at a weight ratio from 2 to 10 wt%.Phase separation between PLA and PLA-PBS was not observed from their scanning electron microscopy(SEM)images and the crystal structure of PLA almost remained unchanged based on the X-ray diffraction(XRD)measurement.The melt flow index(MFI)of the blends was higher as the amount of PLA-PBS increased,indicating that the block copolymer did improve the mobility of the PLA chains.Moreover,tensile tests revealed that PLA with greater PLA-PBS copolymer exhibited higher elongation at break and it reached the maximum at 8 wt%of PLA-PBS in PLA,which was around 6 times higher than that of pure PLA.Furthermore,the glass transition temperature,measured by differential scanning calorimetry(DSC),markedly decreased with an increasing amount of the copolymer as it decreased from 61.2℃ for pure PLA to 41.3℃when it was blended with 10 wt%PLA-PBS copolymer.Therefore,the PLA-PBS copolymer was shown to be a promising plasticizer for fully biobased and toughened PLA.
基金Supported by the Deanship of Scientific Research at Prince Sattam Bin Abdulaziz University under the Research Project No.2015/01/4787
文摘Nonlinear shock wave structures in unmagnetized collisionless viscous plasmas composed fluid of positive(negative) ions and nonthermally electron distribution are examined. For ion shock formation, a reductive perturbation technique applied to derive Burgers equation for lowest-order potential. As the shock amplitude decreasing or enlarging,its steepness and velocity deviate from Burger equation. Burgers type equation with higher order dissipation must be obtained to avoid this deviation. Solution for the compined two equations has been derived using renormalization analysis. Effects of higher-order, positive- negative mass ratio Q, electron nonthermal parameter δ and kinematic viscosities coefficient of positive(negative) ions η1 and η2 on the electrostatic shocks in Earth's ionosphere are also argued.
文摘In the last decade,North Africa has witnessed significant population growth,particularly those bordering the Mediterranean Sea.This led to increased demand for groundwater,which is an essential source for various water uses such as drinking water supplies and irrigation.Generally,human activities play a crucial role in the different quantitative and qualitative changes in groundwater.Now,climate changes such as a decrease in precipitation have also led to a shortage of water resources and a decline in the groundwater table.This paper presents the impact of climate changes on groundwater resources in the Ain Azel region,Setif,northeastern Algeria.The analysis of longterm spatiotemporal variability in rainfall over 63 years(1958–2021)revealed a significant decline in groundwater recharge,especially after 2013.In contrast,the Pettitt and Mann–Kendall tests show increased temperatures with breaks between 1984 and 1986.A piezometric analysis of the alluvial aquifer demonstrated a significant decline in groundwater levels in the last 20 years.Hydrochemical analysis showed that groundwater in the region is dominated by Ca–Mg–Cl water type,which indicates the presence of water salinity phenomenon.Water Quality Index(WQI)analysis showed the deterioration of groundwater in the area,which may be caused by several factors:brine intrusion from the Salt Lake(Sebkha)in the north;the dissolution of evaporites(Triassic)and/or anthropogenic sources of agricultural and industrial origin.Our findings provide an overview summarizing the state of groundwater,which will help improve groundwater resource management in the region in the coming years.
文摘In low carbon steels, dissolution and precipitation of the second phases such as carbides and nitrides during annealing cycles can affect the final structure and properties of the materials. The interaction of above processes depends on parameters such as reheating temperature, heating rate, annealing temperature, soaking time and finishing temperature in hot rolling stage before cold rolling. The effects of heating rate and annealing temperature on the microstructure and hardness were investigated. Two heating rates for annealing temperatures of 550, 610 and 720℃ were applied on cold-rolled specimens and St-14 low carbon steel, which were immediately quenched after isothermal annealing. The intercept method was used tO measure average grain sizes. However, resulted microstructures are dif- ferent for the two heating rates. While pancaked structures were observed in specimens annealed with low heating rate, in samples annealed with high heating rate, equiaxed microstructures were observed. Vickers micro-hardness values decreased at all temperatures, which were more significant at higher temperatures. At longer annealing time, signs of increase of hardness values were detected. All results and observations consistently suggest that a precipitati- on process has occurred concurrently with restoration processes during annealing. In addition, the energy dispersive spectroscopy analysis resulted from transmission electron microscopic micrographs have proved that the nano particles precipitated in grain boundaries are AlN.
基金financially supported by the Faculty of Science,King Mongkut’s Institute of Technology Ladkrabang,Bangkok,Thailand(No.2558-02050067)
文摘In the present study, multiwalled carbon nanotubes（MWCNTs）, gold nanoparticles（AuN Ps）, and glutathione（GSH） were used to fabricate multilayer nanoscale thin films. The composite thin films were fabricated by layer-by-layer technique as the films were constructed by the alternate deposition of cationic and anionic polyelectrolytes. The MWCNTs were modified via a noncovalent surface modification method using poly（diallydimethylammonium chloride） to form a cationic polyelectrolyte. An anionic polyelectrolyte was prepared by the chemical reduction of HAuCl_4 using sodium citrate as both the stabilizing and reducing agent to form anionic AuN Ps. GSH was used as an electrocatalyst toward the electro-oxidation of dopamine. The constructed composite electrode exhibits excellent electrocatalytic activity toward dopamine with a short response time and a wide linear range from 1 to 100 mmol/L. The limits of detection and quantitation of dopamine are（0.316 ± 0.081） mmol/L and（1.054 ± 0.081） mmol/L, respectively. The method is satisfactorily applied for the determination of dopamine in plasma and urine samples to obtain the recovery in the range from 97.90% to 105.00%.
基金funded by the Scientific Research Deanship at University of Ha'il,Saudi Arabia through project number RG-21169。
文摘Combinations of metal and lanthanide oxides have been done through casted films for potential medical applications. In this regard, samarium(Ⅲ) oxide/chromium(Ⅲ) oxide/graphene oxide(GO)/polycaprolactone(PCL) based films nano-composites(NCs) were fabricated, pointing their utilization as a biological scaffold for wound dressing purposes. Also, samarium(Ⅲ) oxide and chromium(Ⅲ) oxide have been merged as promising optical constituents due to their unique optical behavior. The structural and compositional examination of the studied NCs was executed by X-ray diffraction(XRD), Raman, and field emission scanning electron microscopy(FESEM). The Sm_(2)O_(3)/Cr_(2)O_(3)/GO/PCL NC exhibits a surface with a lower roughness degree owing to the presence of GO. Cr_(2)O_(3)shows size reduction upon GO insertion to reach 1.2 μm as the average grain size, whilst Sm_(2)O_(3)records an average grain size of less than 1 μm. As well, the polymeric nano-compositions exhibit variation in contact angle values that hit 29.76°± 3.52°for Sm_(2)O_(3)/PCL, and 48.62°± 1.37°for Sm_(2)O_(3)/Cr_(2)O_(3)/GO/PCL as the second lowest contact angle. The optical behavior contributes to absorption edge relocation along the x-axis from 1.7 eV for pure PCL, to 2.65 eV for Sm_(2)O_(3)/Cr_(2)O_(3)/GO/PCL. Regarding biological responses, the cell exposed to 2.5 μg/m L of Sm_(2)O_(3)/Cr_(2)O_(3)/GO/PCL shows cell viability of 119.31%, while 5 μg/m L hits 99.6%. Additionally, the resulting cell attachment micrographs show layers of fibroblast tissue, besides the proliferation and growth of cultivated cells. Thus, the Sm_(2)O_(3)/Cr_(2)O_(3)/GO/PCL scaffold provides 3D proliferation of fibroblast cells endorsing the wound healing process.
基金funded by the Scientific Research Deanship at University of Ha'il,Saudi Arabia through project number RG-20-222。
文摘Developing a biomaterial for wound healing applications is still a challenge.Herein,dysprosium oxide(Dy_(2)O_(3)),aluminum oxide(Al_(2)O_(3)),and graphene oxide(GO)were embedded in cast films based on polycaprolactone(PCL)to be examined for wound dressing usage.Different techniques were used to characterize the fabricated films including X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),Raman,and scanning electron microscopy(SEM),besides their biological activity.The thermogravimetric analysis(TGA)exhibits high thermal stability as the scaffold weight decreases slightly to 98.6%after raising the temperature from room temperature to 280℃.The cell viability was investigated and it is shown that the viable cells grow up to approximately 93%at 75μg/mL.Meanwhile,the cell attachment shows excellent behavior as the cells attach on most of the surface of the modified PCL which shows high biocompatibility.
基金funded by King Mongkut’s University of Technology North Bangkok,Contract no.KMUTNB-67-KNOW-02by National Science,Research and Innovation Fund(NSRF)+1 种基金King Mongkut’s University of Technology North Bangkok(Project no.KMUTNBeFFe67-B-35)supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)(2021R1C1C1011588).
文摘The tribovoltaic nanogenerator(TVNG)has evolved in recent years as a novel type of nanogenerator designed to address the limitations of the standard triboelectric nanogenerator in terms of output signal and charge generation.Besides the outstanding characteristics,the tribovoltaic effect can also well be coupled with another effect to further boost the output performance.In this work,we proposed firstly a frictional heat-assisted performance enhancement in dynamic Schottky contact from the rubbing between n-type silver selenide(Ag_(2)Se)and aluminum.The chemical composition and physical characteristics of the Ag_(2)Se ceramic were analyzed using X-ray diffraction,scanning electron microscopy,and Synchrotron X-ray tomography techniques.UVeVis spectroscopy and UPS were also utilized in order to validate the semiconducting property of the n-type Ag_(2)Se ceramic.Moreover,the presence of the Schottky junction was demonstrated through the analysis of the current-bias voltage characteristic curve of the Ag_(2)Se/aluminum(Al)contact under varying stress and temperature conditions.The built-in electric field plays a crucial part in the tribovoltaic effect by efficiently transferring the excited carriers to an external load through sliding contact between Ag_(2)Se and Al.Demonstrating the synergy between tribovoltaic and thermoelectric effects becomes achievable through the excellent thermoelectric property of Ag_(2)Se.Herein,the proposed TVNG generated a peak output voltage and current of around 0.7 V and 24.8 nA,respectively,achieving a maximum output power of 12.6 nW at a load resistance of 10 kU.The influence of frictional heat on the output performance of the proposed TVNG was well demonstrated by the thermal-induced voltage and enhanced electrical output from continuous sliding.The concepts given in this study establish the basis for the progress of effective energy collection employing semiconducting materials and the advancement of flexible harvesting and sensing device development in the future.
基金supported by IAEA(Coordinated Research Project,F22081)Thailand Institute of Nuclear Technology(Public organization)+1 种基金Thailand Science Research and Innovation(TSRI)National Science,Research and Innovation Fund(NSRF).
文摘High quantum yield carbon dot(CD)was synthesized from water hyacinth leaves(WH)through ionizing gamma radiation,eliminating the need for heat or chemical treatments.The study investigated the effects of different gamma doses(50,100,150 kGy)on the resulting CD’s optical properties,particle sizes,and surface chemistry.The 50 kGy dose produced CD(CD50)with a remarkable quantum yield of 48.3%.Polyvinyl alcohol(PVA)-CD50 composite films demonstrated enhanced root growth in Chinese convolvulus by 19%and were non-toxic to human cells.These composites also proved effective for food packaging applications,as evidenced by the reduced color changes in strawberries under UV light exposure.This study introduces a green synthesis approach for transforming invasive water hyacinth into a high-value CD,with promising applications in electronics,catalysis,and sensing.
基金Science&Technology Fundamental resources investigation program(Grant No.2022FY101300)Guangdong Basic and Applied Basic Research Foundation(Grant 2023A1515110926).
文摘Bipolar electrochemistry is a high-throughput corrosion testing method capable of applying a quasi-linear potential gradient across test specimens.This study employs-bipolar electrochemistry corrosion testing to investigate the influence of gravity on pitting corrosion of type 304L and 420 stainless steel across a broad range of applied potentials.Gravity modifies the distribution of current density on the bipolar electrode without altering the potential distribution.The impact of gravity on pitting corrosion is achieved through its effects on the dilution of the electrolyte and the removal of the salt film within the pits.Pits oriented in a face up position demonstrate smoother morphologies,larger cross-sectional areas and pit volumes.In contrast,pits oriented in perpendicular and facedown positions exhibit pit shape.Under conditions governed by diffusion and activation control,pits can up to over 100μm.Additionally,crystallographic pits are observed to form in areas subjected to high applied potentials.
