The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible a...The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible approach is presented to repair TA15 forgings by employing Ti6Al4V-xTA15 mixed powders in this paper.The performance compatibility of Ti6Al4V-xTA15 powders from the aspects of microhardness,tensile property,heat capacity,thermal expansion coefficient and corrosion resistance with the TA15 forgings was fully investigated.The primaryαlaths were refined and the volume fraction of the secondaryαphase was increased by increasing the mass fraction of TA15 in the mixed Ti6Al4V-xTA15 powders,leading to varied performances.In conclusion,the mixed Ti6Al4V-70%TA15(x=70%)powders is the most suitable candidate and is recommended as the raw material for LAR of TA15 forgings based on overall consideration of the compatibility calculations of the laser repaired zone with the wrought substrate zone.展开更多
While the significant role of technological innovation in promoting renewable energy has been extensively explored in the literature,limited attention has been paid to the impact of energy patents,particularly clean e...While the significant role of technological innovation in promoting renewable energy has been extensively explored in the literature,limited attention has been paid to the impact of energy patents,particularly clean energy patents and fossil fuel patents.This study pioneers an investigation into the effects of energy patents and energy prices on renewable energy consumption.The study utilizes data from 2000Q1 to 2023Q4 and,due to the nonlinear nature of the series,applies wavelet quantile-based methods.Specifically,it introduces the wavelet quantile cointegration approach to evaluate cointegration across different quantiles and time horizons,along with the wavelet quantile-on-quantile regression method.The results confirm cointegration across different periods and quantiles,highlighting the significant relationships between energy patents,economic factors,and renewable energy consumption.Furthermore,we found that fossil energy patents negatively affect renewable energy consumption,while clean energy patents have a similar but weaker effect,especially in the short term.In addition,higher energy prices promote renewable energy adoption while economic growth positively influences renewable energy consumption,particularly in the short term.The study formulates specific policies based on these findings.展开更多
This study examines the impact of artificial intelligence(AI)on carbon inequality(CI)in 67 countries from 1995 to 2019.The results suggest that(i)AI significantly amplifies CI both between and within countries due to ...This study examines the impact of artificial intelligence(AI)on carbon inequality(CI)in 67 countries from 1995 to 2019.The results suggest that(i)AI significantly amplifies CI both between and within countries due to its energy requirements and uneven deployment;(ii)trade openness and global value chain(GVC)positioning mitigate AI’s effect on inter-country CI,while robust governance—marked by larger government size and institutional transparency—curtails intra-country disparities;(iii)specific thresholds(trade openness>4.74,GVC position>−1.07,government size>2.90,transparency>−0.22)shift the impact of AI from exacerbating to reducing CI.The adverse effects of AI can be reversed through enhanced trade,GVC integration,and strong governance.Key policy implications:Policymakers must prioritize exceeding these thresholds to leverage AI for sustainable and equitable outcomes.This requires(a)promoting trade liberalization to spread the benefits of AI globally,reducing inter-country CI;(b)strengthening GVC participation to offset the carbon-intensive use of AI;(c)building government capacity and transparency to ensure fair adoption of AI domestically;and(d)embedding these strategies in climate policies to align AI with the long-term goals of environmental justice and the SDGs,particularly climate action(SDG 13)and reducing inequalities(SDG 10).展开更多
Size reduction of the gas turbines(GT)by reducing the inlet S-shaped diffuser length increases the powerto-weight ratio.It improves the techno-economic features of the GT by lesser fuel consumption.However,this Length...Size reduction of the gas turbines(GT)by reducing the inlet S-shaped diffuser length increases the powerto-weight ratio.It improves the techno-economic features of the GT by lesser fuel consumption.However,this Length reduction of a bare S-shaped diffuser to an aggressive S-shaped diffuser would risk flow separation and performance reduction of the diffuser and the air intake of the GT.The objective of this research is to propose and assess fitted energy promoters(EPs)to enhance the S-shaped diffuser performance by controlling and modifying the flow in the high bending zone of the diffuser.After experimental assessment,the work has been extended to cover more cases by numerical investigations on bare,bare aggressive,and aggressive with energy promoters S-shaped diffusers.Three types of EPs,namely co-rotating low-profile,co-rotating streamline sheet,and trapezoidal submerged EPs were tested with various combinations over a range of Reynolds numbers from 40,000 to 75,000.The respective S-shaped diffusers were simulated by computational fluid dynamics(CFD)using ANSYS software adopting a steady,3D,standard k-εturbulence model to acquire the details of the flow structure,which cannot be visualized in the experiment.The diffuser performance has been evaluated by the performance indicators of static pressure recovery coefficient,total pressure loss coefficient,and distortion coefficient(DC(45°)).The enhancements in the static pressure recovery of the S-shaped aggressive diffuser with energy promoters are 19.5%,22.2%,and 24.5%with EPs at planes 3,4 and 5,respectively,compared to the aggressive bare diffuser.In addition,the installation of the EPs resulted in a DC(45°)reduction at the outlet plane of the diffuser of about 43%at Re=40,000.The enhancements in the performance parameters confirm that aggravating the internal flow eliminates the flow separation and enhances the GT intake efficiency.展开更多
The recent surge in global financial and patent innovations and rising CO_(2) emissions in the global energy sector have drawn significant attention to China’s transportation industry.This study examines how financia...The recent surge in global financial and patent innovations and rising CO_(2) emissions in the global energy sector have drawn significant attention to China’s transportation industry.This study examines how financial innovations(FINI),patent innovations(PTIN),and bioenergy(BIOE)affect CO_(2) emissions in China’s transportation sector(TBCO_(2))using quarterly data from 2000 to 2018.This study employed a novel wavelet local multiple correlation(WLMC)methodology,alongside the time-varying causality test,to examine the time–frequency nexus,addressing a critical gap in the current literature.The WLMC bivariate analyses revealed a negative long-term relationship between PTIN and FINI with TBCO_(2).At the same time,BIOE showed only a short-term mitigating effect,with PTIN playing a dominant role in this nexus at various frequency levels.Furthermore,the three-and four-variate assessments highlight the consistent positive influence of all included factors on TBCO_(2).A timevarying causality test also demonstrated significant causal relationships between FINI,PTIN,BIOE,and TBCO_(2) across different periods,confirming the robustness of our WLMC results.This study provides crucial insights,emphasizing the urgency of promoting FINIs,technological advancement,and bioenergy usage to reduce transportation emissions and pursue sustainable solutions to address China’s environmental challenges.展开更多
This study analyzes the influence of green bonds on carbon neutrality.It examines the daily data of sectoral CO_(2) emissions of the top five CO_(2)-emitting nations from January 2,2019 to December 30,2022 using wavel...This study analyzes the influence of green bonds on carbon neutrality.It examines the daily data of sectoral CO_(2) emissions of the top five CO_(2)-emitting nations from January 2,2019 to December 30,2022 using wavelet transform coherence,quantile-onquantile regression,Granger causality in quantiles,and quantile regression approaches.The results revealed that(i)green bonds are strongly related to sectoral CO_(2) emissions;(ii)green bonds reduce transport sector CO_(2) emissions in China,the US,and Japan while causing an upsurge in India and Russia;(iii)green bonds reduce industrial sector CO_(2) emissions only in the US;(iv)green bonds have a declining influence in energy sector CO_(2) emissions at lower quantiles in India,China,and the US,whereas the impact increases at higher quantiles;and(v)green bonds decrease residential sector CO_(2) emissions in the US,Russia,and Japan.The study revealed that green bonds help reduce CO_(2) emissions in the residential sector in various quantiles.Therefore,the US,Russia,and Japan should raise household awareness of green energy utilization by promoting them with green bonds.In addition,green bonds can effectively reduce transportation sector CO_(2) emissions in China and the US.Therefore,the policymakers of the two global powers should contribute to global CO_(2) reduction by promoting green transportation and clean energy transition in the transportation sector through green bonds.Thus,green bonds can play an effective role in the fight against global warming.展开更多
BACKGROUND Small-bowel disorders,including obscure gastrointestinal bleeding(OGIB),Crohn's disease,and tumors,require accurate diagnostic approaches for effective treatment.Video capsule endoscopy(VCE)and simple b...BACKGROUND Small-bowel disorders,including obscure gastrointestinal bleeding(OGIB),Crohn's disease,and tumors,require accurate diagnostic approaches for effective treatment.Video capsule endoscopy(VCE)and simple balloon enteroscopy(SBE)are widely used;however,each modality has limitations,particularly regarding therapeutic intervention and diagnostic yield.AIM To evaluate diagnostic yields of various modalities for small bowel bleeding,analyze factors affecting heterogeneity,and improve understanding of clinical outcomes associated with different diagnostic approaches.METHODS A comprehensive search of four databases(PubMed,Embase,Cochrane Library,and Scopus)revealed over 600 citations related to the use of capsule endoscopy and balloon enteroscopy for diagnosing small intestine disorders with wall thickening.Based on predetermined eligibility criteria,seven moderateto-high-quality retrospective studies were analyzed to evaluate the diagnostic performance of VCE and SBE in patients with small bowel disorders.Quality Assessment of Diagnostic Accuracy Studies was applied to evaluate the risk of bias and overall methodological quality.RESULTS Analysis of seven moderate-to-high-quality retrospective studies revealed comparable overall detection rates for small bowel lesions between VCE and SBE.VCE demonstrated superior performance in detecting vascular lesions.Conversely,SBE exhibited a higher efficacy in detecting ulcerative lesions.The overall diagnostic yield varied across studies,with VCE showing a range of 32%–83%for small bowel bleeding,whereas SBE demonstrated a higher overall detection rate of 69.7%compared to 57.6%for VCE(P<0.05).Notably,SBE showed superior performance in diagnosing Crohn's disease,with a detection rate of 35%,compared to 11.3%for VCE(P<0.001).The diagnostic concordance between VCE and SBE was influenced by the lesion type.Strong agreement was observed for inflammatory lesions(κ=0.82,95%CI:0.75-0.89),whereas moderate agreement was noted for tumors(κ=0.61,95%CI:0.52-0.70)and angiectasias(κ=0.58,95%CI:0.49-0.67).SBE demonstrated significant advantages in therapeutic interventions,particularly in overt bleeding.Patient tolerability was generally higher for VCE,with a completion rate of 95%(95%CI:92%-98%),compared to 85%for SBE(95%CI:80%-90%).However,the capsule retention rate for VCE was 1.4%(95%CI:0.8%-2.0%),necessitating subsequent intervention.CONCLUSION VCE and SBE are complementary techniques for evaluating small intestinal disorders.Although VCE remains the initial test of choice for patients with stable OGIB,SBE should be considered in patients requiring therapeutic intervention.Thus,combining both modalities enhances diagnostic accuracy and patient management.展开更多
BACKGROUND Chylous ascites(CA),which is characterized by lymphatic leakage into the peritoneal cavity,is a rare but significant complication of liver transplantation.Although dietary and pharmacological strategies hav...BACKGROUND Chylous ascites(CA),which is characterized by lymphatic leakage into the peritoneal cavity,is a rare but significant complication of liver transplantation.Although dietary and pharmacological strategies have shown effectiveness in managing CA,standardized treatment protocols have yet to be established.AIMTo evaluate the comparative effectiveness of low-fat diet (LFD) enriched with medium-chain triglycerides (MCTs)vs octreotide therapy in managing post-liver transplantation CA.METHODSA comprehensive literature review was conducted to analyze the outcomes of dietary interventions and octreotidetherapy. The key parameters examined included resolution rates, treatment duration, and recurrence.RESULTSA comprehensive literature search yielded 13 studies that met the inclusion criteria, comprising 4 retrospectivecohort studies and 8 case studies. The incidence of CA following liver transplantation ranges from 0.6% to 4.7%.The onset varied, with a median time to diagnosis of 10 days after transplantation. A LFD with MCT supplementationwas used as the first-line therapy in 83.3% of the studies, with resolution rates ranging from 62.5% to100%. Octreotide therapy was utilized in 66.7% of the studies, primarily as a second-line therapy, with resolutionrates of 83.3% to 100%. Combination therapy showed a significantly higher resolution rate than did dietarymanagement alone (97.8% vs 78.9%, P = 0.02). The time to resolution was significantly shorter with octreotidecontainingregimens than with dietary management alone (median, 7 days vs 14 days;P = 0.03).CONCLUSIONA stepwise approach to CA management is recommended, initiating dietary interventions and escalating tooctreotide when necessary. Further research through well-designed randomized controlled trials is essential toestablish standardized treatment protocols for optimizing patient outcomes.展开更多
This study emphasizes on the evaluation and comparison of the anticorrosive properties of sol-gel coatings with and without inhibitor loaded nanocontainers.In this case,naturally available clay nanotubes(halloysite)we...This study emphasizes on the evaluation and comparison of the anticorrosive properties of sol-gel coatings with and without inhibitor loaded nanocontainers.In this case,naturally available clay nanotubes(halloysite)were loaded with cationic corrosion inhibitors Ce 3+/Zr 4+.These nanocontainers were dispersed in hybrid organic-inorganic sol-gel matrix sol.Coating was applied on magnesium alloy AZ91D using the sols containing modified and unmodified nanocontainers employing the dip coating method and cured at 130℃for 1 h in air.Corrosion resistance of coated/uncoated substrates were analyzed using electrochemical impedance spectroscopy,potentiodynamic polarization and weight loss measurements after exposure to 3.5 wt%NaCl solution for varying time durations between 24 h to 120 h.Self-healing ability of coatings was evaluated by micro-Raman spectroscopy after 120 h exposure to 3.5 wt%NaCl solution.Coatings generated after dispersion of corrosion inhibitor loaded clay in hybrid sol-gel matrix have shown more promising corrosion resistance when compared to just the sol-gel matrix coatings,after prolonged exposure to corrosive environment.展开更多
The correlation of microstructure and magnetic properties in Sm(Co_(bal)Fe_(0.1)Cu_(0.1)Zr_(0.033))_(6.93) magnets solution-treated at different temperatures was systematically investigated. It is found that the magne...The correlation of microstructure and magnetic properties in Sm(Co_(bal)Fe_(0.1)Cu_(0.1)Zr_(0.033))_(6.93) magnets solution-treated at different temperatures was systematically investigated. It is found that the magnets solution-treated at 1219℃ possess a single 1:7 H phase, exhibiting the homogeneous cellular structure during further aging treatment, leading to the optimum magnetic properties. However, for the magnets solution-treated at 1211 and 1223℃,2:17 H or 1:5 H secondary phase will also form besides 1:7 H main phase, which cannot transform into cellular structure,thus deteriorating the magnetic properties greatly. The irreversible magnetization investigations with recoil loops also propose a non-uniform pinning in the magnets induced by the secondary precipitates. At proper solution temperature, Zr is supposed to occupy the Fe-Fe dumbbell sites in the form of Zr-vacancy pairs, leading to the minimum c/a ratio and thus stabilizing the 1:7 H phase. Finally,Sm(Co_(bal)Fe_(0.1)Cu_(0.1)Zr_(0.033))_(6.93) magnets with the maximum energy product and intrinsic coercivity at 550℃ up to 60.73 kJ·m^(-3) and 553.88 kA·m^(-1) were prepared by powder metallurgy method.展开更多
Alumina coating was formed on AA7075 aluminum alloy by micro arc oxidation（MAO） method and its corrosion and stress corrosion cracking（SCC） behaviors were examined in 3.5%（mass fraction） NaCl solution.Electroche...Alumina coating was formed on AA7075 aluminum alloy by micro arc oxidation（MAO） method and its corrosion and stress corrosion cracking（SCC） behaviors were examined in 3.5%（mass fraction） NaCl solution.Electrochemical impedance spectroscopy（EIS） was used to evaluate the degradation of the coating as a function of immersion time and was modeled with appropriate equivalent circuits.Constant load stress corrosion cracking（SCC） results followed by post-test metallographic observations demonstrated the usefulness of MAO coating to avoid the premature failure of the alloy due to severe localized corrosion initiated by Cu-and Fe-rich intermetallic phases.展开更多
Morphology controlled synthesis of nanoparticles of powerful high energetic compounds(HECs) such as l,3,5-trinitro-l,3,5-triazinane(RDX) and 1,3,5,7-tetranitro-l,3,5,7-tetrazocane(HMX) were achieved by a simple solven...Morphology controlled synthesis of nanoparticles of powerful high energetic compounds(HECs) such as l,3,5-trinitro-l,3,5-triazinane(RDX) and 1,3,5,7-tetranitro-l,3,5,7-tetrazocane(HMX) were achieved by a simple solvent—antisolvent interaction(SAI) method at 70 ℃.The effects of different solvents on particle size and morphology of the prepared nano-HECs were studied systematically.Particle size and morphology of the nano-HECs was characterized using field emission scanning electron microscopy(FE-SEM) imaging.X-ray diffraction(XRD) and Fourier transform infrared(FTIR) spectroscopy studies revealed that RDX and HMX were precipitated in their most stable polymorphic forms,i.e.a and P,respectively.Thermogravimetric analysis coupled with differential scanning calorimetry(TGA-DSC) studies showed that the thermal response of the nanoparticles was similar to the respective raw-HECs.HEC nanoparticles with spherical and rod shaped morphology were observed under different solvent conditions.The mean particle size also varied considerably with the use of different solvents.展开更多
The effects of different Zn contents in Al-Mg alloy on the microstructure characterizations were observed by advanced electron microscopy and the corrosion properties were investigated by the inter-granular corrosion ...The effects of different Zn contents in Al-Mg alloy on the microstructure characterizations were observed by advanced electron microscopy and the corrosion properties were investigated by the inter-granular corrosion tests,the exfoliation corrosion tests,and the Potentiodynamic polarizaion tests.The τ phase(Mg_(32)(Al,Zn)_(49)) forms on the pre-existing Mn-rich particles and at the grain boundaries.According to the theory of binding energy,the formation of τ phase is much easier than that of β phase(Al_3Mg_2),somehow replacing β phase and reducing the possibility of β phase precipitation.This change dramatically decreases the susceptibility of corrosion.The Zn addition increases the corrosion resistance of Al-Mg alloy with an optimal value of 0.31%.When the Zn addition is increased to 0.78%,however,the corrosion resistance of alloy decreases once again but it is still better than that of the alloy without Zn addition.展开更多
Researchers seldom study the optimum design of a mechanical connector for subsea oil-gas pipeline based upon the sealing performance. An optimal design method of a novel subsea pipeline mechanical connector is present...Researchers seldom study the optimum design of a mechanical connector for subsea oil-gas pipeline based upon the sealing performance. An optimal design method of a novel subsea pipeline mechanical connector is presented. By analyzing the static metal sealing mechanism, the critical condition of the sealing performance is established for this connector and the formulation method of the contact pressure on the sealing surface is created. By the method the minimum mean contact pressure of the 8.625 inch connector is calculated as 361 MPa, which is the constraint condition in the optimum design of connector.The finite element model is created in ANSYS Parametric Design Language(APDL) and the structure is optimized by the zero-order method, with variance of contact pressure as the objective function, and mean contact pressures and plastic strains as constraint variables. The optimization shows that variances of contact pressure on two sealing surfaces decrease by 72.41% and 89.33%, respectively, and mean contact pressures increase by 31.18% and 52.84%, respectively. The comparison of the optimal connectors and non-optimal connectors in the water pressure experiments and bending experiments shows that the sealing ability of optimized connectors is much higher than the rated pressure of 4.5 MPa, and the optimal connectors don’t leak under the bending moment of 52.2 kN·m.This research provides the formulation to solve contact pressure on the sealing surface and a structure optimization method to design the connectors with various dimensions.展开更多
Halloysite nanotubes were used as nanocontainers to hold corrosion inhibitors such as Ce^(3+)-Zr^(4+),2-mercaptobenzothiazole and 8-hydroxyquinoline in their lumen.An acid assisted etching of the nanotubes was carried...Halloysite nanotubes were used as nanocontainers to hold corrosion inhibitors such as Ce^(3+)-Zr^(4+),2-mercaptobenzothiazole and 8-hydroxyquinoline in their lumen.An acid assisted etching of the nanotubes was carried out with a view to increase the lumen diameter and thereby,increase the amount of loading of the corrosion inhibitor.The morphology of as-received and etched halloysite nanotubes was ob-served using TEM analysis.The loading of corrosion inhibitors was confirmed using SEM-EDS and BET analysis.Polymeric microcapsules were used as capping agents for the ends of the loaded HNTs following which,they were dispersed into a hybrid sol-gel silica matrix.Dip coating method was used to generate coatings on AZ91D substrates followed by heat treatment at 130℃ for 1 h.The release rate kinetics of corrosion inhibitors from as-received and etched nanotubes was investigated in buffer solutions of 3.5 wt%NaCl at different pH.The release mechanism of corrosion inhibitors from the HNT lumen was validated using various semi-empirical models.Coatings were also evaluated for their corrosion protection ability using electrochemical techniques after exposure to 3.5 wt%NaCl solution for 120 h.Coatings generated using Ce^(3+)-Zr^(4+)loaded into as-received halloysite nanotubes have shown more effective corrosion protection when compared to other corrosion inhibitors after 120 h exposure to the corrosive medium.展开更多
The neutral zinc sulfate solution obtained from hydrometallurgical process of Angouran zinc concentrate has cadmium, nickel and cobalt impurities, that must be purified before electrowinning. Therefore, cadmium and ni...The neutral zinc sulfate solution obtained from hydrometallurgical process of Angouran zinc concentrate has cadmium, nickel and cobalt impurities, that must be purified before electrowinning. Therefore, cadmium and nickel are usually cemented out by addition of zinc dust and remained nickel and cobalt cemented out at second stage with zinc powder and arsenic trioxide. In this research, a new approach is described for determination of effective parameters and optimization of zinc electrolyte hot purification process using statistical design of experiments. The Taguchi method based on orthogonal array design（OAD） has been used to arrange the experimental runs. The experimental conditions involved in the work are as follows： the temperature range of 70-90 ℃ for reaction temperature（T）, 30-90 min for reaction time（t）, 2-4 g/L for zinc powder mass concentration（M）, one to five series for zinc dust particle size distributions（S1-S5）, and 0.1-0.5 g/L（C） for arsenic trioxide mass concentration. Optimum conditions for hot purification obtained in this work are T4（85 ℃）, t4=75 min, M4=3.5 g/L, S4（Serie 4）, and C2=0.2 g/L.展开更多
Behavior of the coercivity of the high-temperature Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was investigated.It...Behavior of the coercivity of the high-temperature Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was investigated.It is shown that the growth rate of coercivity abruptly increases at the initial stage of annealing in the vicinity of the Curie temperature of the SmCo5 phase.The origin of the effect is the counter diffusion of Cu and Co atoms through dislocation tubes,which form because of enhanced stresses and a partial breakage of coherent coupling at the interface of the Sm2 Co17 and SmCo5 phases.Diffusive enrichment of the SmCo5 phase in Cu close to the interface with Sm2 Co17 leads to relaxation of stresses and increases in the gradient of the magnetic domain-wall energy and coercivity.展开更多
This study investigated the hot corrosion performance of a dissimilar weldment of Ni-based superalloy and stainless steel joined by CO2-laser welding and improved by high-velocity oxy-fuel(HVOF)coating in a Na2SO4-60w...This study investigated the hot corrosion performance of a dissimilar weldment of Ni-based superalloy and stainless steel joined by CO2-laser welding and improved by high-velocity oxy-fuel(HVOF)coating in a Na2SO4-60wt%V2O5 environment at 900℃.A dissimilar butt joint of AISI 321 and alloy 825 was fabricated by CO2-laser welding with low heat input after obtaining the optimum welding parameters by bead-on-plate trials.The metallurgical and mechanical properties of the laser weldment were evaluated.The tensile test results indicated the occurrence of fracture in the base metal AISI 321 side.The HVOF process was employed to coat Ni-20wt%Cr on the weldment.To evaluate the surface morphology of the corrosion products formed on the uncoated and Ni-20wt%Cr-coated weldments,scanning electron microscopy(SEM)analysis was performed.Energy-dispersive spectroscopy(EDS)was used to determine the different elements present on the surface scales.The existence of oxide phases on the weldments was determined by X-ray diffraction(XRD).The cross sections of the weldments were characterized by SEM with EDS line mapping analysis.The results indicated that the Ni-20wt%Cr-coated weldment exhibited superior hot corrosion resistance due to the development of Cr2O3 and NiCr2O4 protective oxide scales.展开更多
High-efficiency perovskite solar cells（PSCs） reported hitherto have been mostly prepared in a moisture and oxygen-free glove-box atmosphere, which hampers upscaling and real-time performance assessment of this excit...High-efficiency perovskite solar cells（PSCs） reported hitherto have been mostly prepared in a moisture and oxygen-free glove-box atmosphere, which hampers upscaling and real-time performance assessment of this exciting photovoltaic technology. In this work, we have systematically studied the feasibility of allambient-processing of PSCs and evaluated their photovoltaic performance. It has been shown that phasepure crystalline tetragonal MAPbI;perovskite films are instantly formed in ambient air at room temperature by a two-step spin coating process, undermining the need for dry atmosphere and post-annealing.All-ambient-processed PSCs with a configuration of FTO/TiO;/MAPbI;/Spiro-OMeTAD/Au achieve opencircuit voltage（990 mV） and short-circuit current density（20.31 mA/cm;） comparable to those of best reported glove-box processed devices. Nevertheless, device power conversion efficiency is still constrained at 5% by the unusually low fill-factor of 0.25. Dark current–voltage characteristics reveal poor conductivity of hole-transporting layer caused by lack of oxidized spiro-OMe TAD species, resulting in high seriesresistance and decreased fill-factor. The study also establishes that the above limitations can be readily overcome by employing an inorganic p-type semiconductor, copper thiocyanate, as ambient-processable hole-transporting layer to yield a fill-factor of 0.54 and a power conversion efficiency of 7.19%. The present findings can have important implications in industrially viable fabrication of large-area PSCs.展开更多
Multiwalled carbon nanotubes （MWCNTs） reinforced Cu-Sn alloy based nanocomposite was developed by powder metallurgy route. The mass fraction of CNTs was varied from 0 to 2% in a step of 0.5%. The developed nanocompo...Multiwalled carbon nanotubes （MWCNTs） reinforced Cu-Sn alloy based nanocomposite was developed by powder metallurgy route. The mass fraction of CNTs was varied from 0 to 2% in a step of 0.5%. The developed nanocomposites were subjected to density, hardness, electrical conductivity, and friction and wear tests. The results reveal that the density of nanocomposite decreases with the increase of the mass fraction of CNTs. A significant improvement in the hardness is noticed in the nanocomposite with the addition of CNTs. The developed nanocomposites show low coefficient of friction and improved wear resistance when compared with unreinforced alloy. At an applied load of 5 N, the coefficient of friction and wear loss of 2%CNTs reinforced Cu-Sn alloy nanocomposite decrease by 72% and 68%, respectively, compared with those of Cu-Sn alloy. The wear mechanisms of worn surfaces of the composites are reported. In addition, the electrical conductivity reduces with the increase of the content of CNTs.展开更多
基金Project(2019-00899-1-1)supported by the Ministry of Industry and Information Technology of ChinaProject(2021JM-060)supported by the Natural Science Foundation of Shaanxi Province,ChinaProject(3102019QD0409)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible approach is presented to repair TA15 forgings by employing Ti6Al4V-xTA15 mixed powders in this paper.The performance compatibility of Ti6Al4V-xTA15 powders from the aspects of microhardness,tensile property,heat capacity,thermal expansion coefficient and corrosion resistance with the TA15 forgings was fully investigated.The primaryαlaths were refined and the volume fraction of the secondaryαphase was increased by increasing the mass fraction of TA15 in the mixed Ti6Al4V-xTA15 powders,leading to varied performances.In conclusion,the mixed Ti6Al4V-70%TA15(x=70%)powders is the most suitable candidate and is recommended as the raw material for LAR of TA15 forgings based on overall consideration of the compatibility calculations of the laser repaired zone with the wrought substrate zone.
文摘While the significant role of technological innovation in promoting renewable energy has been extensively explored in the literature,limited attention has been paid to the impact of energy patents,particularly clean energy patents and fossil fuel patents.This study pioneers an investigation into the effects of energy patents and energy prices on renewable energy consumption.The study utilizes data from 2000Q1 to 2023Q4 and,due to the nonlinear nature of the series,applies wavelet quantile-based methods.Specifically,it introduces the wavelet quantile cointegration approach to evaluate cointegration across different quantiles and time horizons,along with the wavelet quantile-on-quantile regression method.The results confirm cointegration across different periods and quantiles,highlighting the significant relationships between energy patents,economic factors,and renewable energy consumption.Furthermore,we found that fossil energy patents negatively affect renewable energy consumption,while clean energy patents have a similar but weaker effect,especially in the short term.In addition,higher energy prices promote renewable energy adoption while economic growth positively influences renewable energy consumption,particularly in the short term.The study formulates specific policies based on these findings.
基金supported by National Natural Science Foundation of China(Grant No.72104246).
文摘This study examines the impact of artificial intelligence(AI)on carbon inequality(CI)in 67 countries from 1995 to 2019.The results suggest that(i)AI significantly amplifies CI both between and within countries due to its energy requirements and uneven deployment;(ii)trade openness and global value chain(GVC)positioning mitigate AI’s effect on inter-country CI,while robust governance—marked by larger government size and institutional transparency—curtails intra-country disparities;(iii)specific thresholds(trade openness>4.74,GVC position>−1.07,government size>2.90,transparency>−0.22)shift the impact of AI from exacerbating to reducing CI.The adverse effects of AI can be reversed through enhanced trade,GVC integration,and strong governance.Key policy implications:Policymakers must prioritize exceeding these thresholds to leverage AI for sustainable and equitable outcomes.This requires(a)promoting trade liberalization to spread the benefits of AI globally,reducing inter-country CI;(b)strengthening GVC participation to offset the carbon-intensive use of AI;(c)building government capacity and transparency to ensure fair adoption of AI domestically;and(d)embedding these strategies in climate policies to align AI with the long-term goals of environmental justice and the SDGs,particularly climate action(SDG 13)and reducing inequalities(SDG 10).
文摘Size reduction of the gas turbines(GT)by reducing the inlet S-shaped diffuser length increases the powerto-weight ratio.It improves the techno-economic features of the GT by lesser fuel consumption.However,this Length reduction of a bare S-shaped diffuser to an aggressive S-shaped diffuser would risk flow separation and performance reduction of the diffuser and the air intake of the GT.The objective of this research is to propose and assess fitted energy promoters(EPs)to enhance the S-shaped diffuser performance by controlling and modifying the flow in the high bending zone of the diffuser.After experimental assessment,the work has been extended to cover more cases by numerical investigations on bare,bare aggressive,and aggressive with energy promoters S-shaped diffusers.Three types of EPs,namely co-rotating low-profile,co-rotating streamline sheet,and trapezoidal submerged EPs were tested with various combinations over a range of Reynolds numbers from 40,000 to 75,000.The respective S-shaped diffusers were simulated by computational fluid dynamics(CFD)using ANSYS software adopting a steady,3D,standard k-εturbulence model to acquire the details of the flow structure,which cannot be visualized in the experiment.The diffuser performance has been evaluated by the performance indicators of static pressure recovery coefficient,total pressure loss coefficient,and distortion coefficient(DC(45°)).The enhancements in the static pressure recovery of the S-shaped aggressive diffuser with energy promoters are 19.5%,22.2%,and 24.5%with EPs at planes 3,4 and 5,respectively,compared to the aggressive bare diffuser.In addition,the installation of the EPs resulted in a DC(45°)reduction at the outlet plane of the diffuser of about 43%at Re=40,000.The enhancements in the performance parameters confirm that aggravating the internal flow eliminates the flow separation and enhances the GT intake efficiency.
基金supported by Key Project of National Social Fund of China(21AGL014).
文摘The recent surge in global financial and patent innovations and rising CO_(2) emissions in the global energy sector have drawn significant attention to China’s transportation industry.This study examines how financial innovations(FINI),patent innovations(PTIN),and bioenergy(BIOE)affect CO_(2) emissions in China’s transportation sector(TBCO_(2))using quarterly data from 2000 to 2018.This study employed a novel wavelet local multiple correlation(WLMC)methodology,alongside the time-varying causality test,to examine the time–frequency nexus,addressing a critical gap in the current literature.The WLMC bivariate analyses revealed a negative long-term relationship between PTIN and FINI with TBCO_(2).At the same time,BIOE showed only a short-term mitigating effect,with PTIN playing a dominant role in this nexus at various frequency levels.Furthermore,the three-and four-variate assessments highlight the consistent positive influence of all included factors on TBCO_(2).A timevarying causality test also demonstrated significant causal relationships between FINI,PTIN,BIOE,and TBCO_(2) across different periods,confirming the robustness of our WLMC results.This study provides crucial insights,emphasizing the urgency of promoting FINIs,technological advancement,and bioenergy usage to reduce transportation emissions and pursue sustainable solutions to address China’s environmental challenges.
文摘This study analyzes the influence of green bonds on carbon neutrality.It examines the daily data of sectoral CO_(2) emissions of the top five CO_(2)-emitting nations from January 2,2019 to December 30,2022 using wavelet transform coherence,quantile-onquantile regression,Granger causality in quantiles,and quantile regression approaches.The results revealed that(i)green bonds are strongly related to sectoral CO_(2) emissions;(ii)green bonds reduce transport sector CO_(2) emissions in China,the US,and Japan while causing an upsurge in India and Russia;(iii)green bonds reduce industrial sector CO_(2) emissions only in the US;(iv)green bonds have a declining influence in energy sector CO_(2) emissions at lower quantiles in India,China,and the US,whereas the impact increases at higher quantiles;and(v)green bonds decrease residential sector CO_(2) emissions in the US,Russia,and Japan.The study revealed that green bonds help reduce CO_(2) emissions in the residential sector in various quantiles.Therefore,the US,Russia,and Japan should raise household awareness of green energy utilization by promoting them with green bonds.In addition,green bonds can effectively reduce transportation sector CO_(2) emissions in China and the US.Therefore,the policymakers of the two global powers should contribute to global CO_(2) reduction by promoting green transportation and clean energy transition in the transportation sector through green bonds.Thus,green bonds can play an effective role in the fight against global warming.
文摘BACKGROUND Small-bowel disorders,including obscure gastrointestinal bleeding(OGIB),Crohn's disease,and tumors,require accurate diagnostic approaches for effective treatment.Video capsule endoscopy(VCE)and simple balloon enteroscopy(SBE)are widely used;however,each modality has limitations,particularly regarding therapeutic intervention and diagnostic yield.AIM To evaluate diagnostic yields of various modalities for small bowel bleeding,analyze factors affecting heterogeneity,and improve understanding of clinical outcomes associated with different diagnostic approaches.METHODS A comprehensive search of four databases(PubMed,Embase,Cochrane Library,and Scopus)revealed over 600 citations related to the use of capsule endoscopy and balloon enteroscopy for diagnosing small intestine disorders with wall thickening.Based on predetermined eligibility criteria,seven moderateto-high-quality retrospective studies were analyzed to evaluate the diagnostic performance of VCE and SBE in patients with small bowel disorders.Quality Assessment of Diagnostic Accuracy Studies was applied to evaluate the risk of bias and overall methodological quality.RESULTS Analysis of seven moderate-to-high-quality retrospective studies revealed comparable overall detection rates for small bowel lesions between VCE and SBE.VCE demonstrated superior performance in detecting vascular lesions.Conversely,SBE exhibited a higher efficacy in detecting ulcerative lesions.The overall diagnostic yield varied across studies,with VCE showing a range of 32%–83%for small bowel bleeding,whereas SBE demonstrated a higher overall detection rate of 69.7%compared to 57.6%for VCE(P<0.05).Notably,SBE showed superior performance in diagnosing Crohn's disease,with a detection rate of 35%,compared to 11.3%for VCE(P<0.001).The diagnostic concordance between VCE and SBE was influenced by the lesion type.Strong agreement was observed for inflammatory lesions(κ=0.82,95%CI:0.75-0.89),whereas moderate agreement was noted for tumors(κ=0.61,95%CI:0.52-0.70)and angiectasias(κ=0.58,95%CI:0.49-0.67).SBE demonstrated significant advantages in therapeutic interventions,particularly in overt bleeding.Patient tolerability was generally higher for VCE,with a completion rate of 95%(95%CI:92%-98%),compared to 85%for SBE(95%CI:80%-90%).However,the capsule retention rate for VCE was 1.4%(95%CI:0.8%-2.0%),necessitating subsequent intervention.CONCLUSION VCE and SBE are complementary techniques for evaluating small intestinal disorders.Although VCE remains the initial test of choice for patients with stable OGIB,SBE should be considered in patients requiring therapeutic intervention.Thus,combining both modalities enhances diagnostic accuracy and patient management.
文摘BACKGROUND Chylous ascites(CA),which is characterized by lymphatic leakage into the peritoneal cavity,is a rare but significant complication of liver transplantation.Although dietary and pharmacological strategies have shown effectiveness in managing CA,standardized treatment protocols have yet to be established.AIMTo evaluate the comparative effectiveness of low-fat diet (LFD) enriched with medium-chain triglycerides (MCTs)vs octreotide therapy in managing post-liver transplantation CA.METHODSA comprehensive literature review was conducted to analyze the outcomes of dietary interventions and octreotidetherapy. The key parameters examined included resolution rates, treatment duration, and recurrence.RESULTSA comprehensive literature search yielded 13 studies that met the inclusion criteria, comprising 4 retrospectivecohort studies and 8 case studies. The incidence of CA following liver transplantation ranges from 0.6% to 4.7%.The onset varied, with a median time to diagnosis of 10 days after transplantation. A LFD with MCT supplementationwas used as the first-line therapy in 83.3% of the studies, with resolution rates ranging from 62.5% to100%. Octreotide therapy was utilized in 66.7% of the studies, primarily as a second-line therapy, with resolutionrates of 83.3% to 100%. Combination therapy showed a significantly higher resolution rate than did dietarymanagement alone (97.8% vs 78.9%, P = 0.02). The time to resolution was significantly shorter with octreotidecontainingregimens than with dietary management alone (median, 7 days vs 14 days;P = 0.03).CONCLUSIONA stepwise approach to CA management is recommended, initiating dietary interventions and escalating tooctreotide when necessary. Further research through well-designed randomized controlled trials is essential toestablish standardized treatment protocols for optimizing patient outcomes.
基金financial sup-port from SERB,DST for the funding provided through grant number SB/S3/ME/007/2014.
文摘This study emphasizes on the evaluation and comparison of the anticorrosive properties of sol-gel coatings with and without inhibitor loaded nanocontainers.In this case,naturally available clay nanotubes(halloysite)were loaded with cationic corrosion inhibitors Ce 3+/Zr 4+.These nanocontainers were dispersed in hybrid organic-inorganic sol-gel matrix sol.Coating was applied on magnesium alloy AZ91D using the sols containing modified and unmodified nanocontainers employing the dip coating method and cured at 130℃for 1 h in air.Corrosion resistance of coated/uncoated substrates were analyzed using electrochemical impedance spectroscopy,potentiodynamic polarization and weight loss measurements after exposure to 3.5 wt%NaCl solution for varying time durations between 24 h to 120 h.Self-healing ability of coatings was evaluated by micro-Raman spectroscopy after 120 h exposure to 3.5 wt%NaCl solution.Coatings generated after dispersion of corrosion inhibitor loaded clay in hybrid sol-gel matrix have shown more promising corrosion resistance when compared to just the sol-gel matrix coatings,after prolonged exposure to corrosive environment.
基金financially supported by the National Natural Science Foundation of China(No. 51471016)the Natural Science Foundation of Beijing(No. 2151002)+1 种基金the BRICS STI Framework Program (Nos. 51761145026 and 17-52-80072)Department of Science and Technology,Govt of India, for supporting the work under DSTBRICS proposal reg.No 258
文摘The correlation of microstructure and magnetic properties in Sm(Co_(bal)Fe_(0.1)Cu_(0.1)Zr_(0.033))_(6.93) magnets solution-treated at different temperatures was systematically investigated. It is found that the magnets solution-treated at 1219℃ possess a single 1:7 H phase, exhibiting the homogeneous cellular structure during further aging treatment, leading to the optimum magnetic properties. However, for the magnets solution-treated at 1211 and 1223℃,2:17 H or 1:5 H secondary phase will also form besides 1:7 H main phase, which cannot transform into cellular structure,thus deteriorating the magnetic properties greatly. The irreversible magnetization investigations with recoil loops also propose a non-uniform pinning in the magnets induced by the secondary precipitates. At proper solution temperature, Zr is supposed to occupy the Fe-Fe dumbbell sites in the form of Zr-vacancy pairs, leading to the minimum c/a ratio and thus stabilizing the 1:7 H phase. Finally,Sm(Co_(bal)Fe_(0.1)Cu_(0.1)Zr_(0.033))_(6.93) magnets with the maximum energy product and intrinsic coercivity at 550℃ up to 60.73 kJ·m^(-3) and 553.88 kA·m^(-1) were prepared by powder metallurgy method.
文摘Alumina coating was formed on AA7075 aluminum alloy by micro arc oxidation（MAO） method and its corrosion and stress corrosion cracking（SCC） behaviors were examined in 3.5%（mass fraction） NaCl solution.Electrochemical impedance spectroscopy（EIS） was used to evaluate the degradation of the coating as a function of immersion time and was modeled with appropriate equivalent circuits.Constant load stress corrosion cracking（SCC） results followed by post-test metallographic observations demonstrated the usefulness of MAO coating to avoid the premature failure of the alloy due to severe localized corrosion initiated by Cu-and Fe-rich intermetallic phases.
基金Financial assistance from ARMREB(DRDO) under grant No.ARMREB/CDSW/2012/149
文摘Morphology controlled synthesis of nanoparticles of powerful high energetic compounds(HECs) such as l,3,5-trinitro-l,3,5-triazinane(RDX) and 1,3,5,7-tetranitro-l,3,5,7-tetrazocane(HMX) were achieved by a simple solvent—antisolvent interaction(SAI) method at 70 ℃.The effects of different solvents on particle size and morphology of the prepared nano-HECs were studied systematically.Particle size and morphology of the nano-HECs was characterized using field emission scanning electron microscopy(FE-SEM) imaging.X-ray diffraction(XRD) and Fourier transform infrared(FTIR) spectroscopy studies revealed that RDX and HMX were precipitated in their most stable polymorphic forms,i.e.a and P,respectively.Thermogravimetric analysis coupled with differential scanning calorimetry(TGA-DSC) studies showed that the thermal response of the nanoparticles was similar to the respective raw-HECs.HEC nanoparticles with spherical and rod shaped morphology were observed under different solvent conditions.The mean particle size also varied considerably with the use of different solvents.
基金Project(2011-006)supported by the State Administration of Science,Technology and Industry for National Defence,China
文摘The effects of different Zn contents in Al-Mg alloy on the microstructure characterizations were observed by advanced electron microscopy and the corrosion properties were investigated by the inter-granular corrosion tests,the exfoliation corrosion tests,and the Potentiodynamic polarizaion tests.The τ phase(Mg_(32)(Al,Zn)_(49)) forms on the pre-existing Mn-rich particles and at the grain boundaries.According to the theory of binding energy,the formation of τ phase is much easier than that of β phase(Al_3Mg_2),somehow replacing β phase and reducing the possibility of β phase precipitation.This change dramatically decreases the susceptibility of corrosion.The Zn addition increases the corrosion resistance of Al-Mg alloy with an optimal value of 0.31%.When the Zn addition is increased to 0.78%,however,the corrosion resistance of alloy decreases once again but it is still better than that of the alloy without Zn addition.
基金Supported by National Natural Science Foundation of China(Grant Nos.51279042,51105088)
文摘Researchers seldom study the optimum design of a mechanical connector for subsea oil-gas pipeline based upon the sealing performance. An optimal design method of a novel subsea pipeline mechanical connector is presented. By analyzing the static metal sealing mechanism, the critical condition of the sealing performance is established for this connector and the formulation method of the contact pressure on the sealing surface is created. By the method the minimum mean contact pressure of the 8.625 inch connector is calculated as 361 MPa, which is the constraint condition in the optimum design of connector.The finite element model is created in ANSYS Parametric Design Language(APDL) and the structure is optimized by the zero-order method, with variance of contact pressure as the objective function, and mean contact pressures and plastic strains as constraint variables. The optimization shows that variances of contact pressure on two sealing surfaces decrease by 72.41% and 89.33%, respectively, and mean contact pressures increase by 31.18% and 52.84%, respectively. The comparison of the optimal connectors and non-optimal connectors in the water pressure experiments and bending experiments shows that the sealing ability of optimized connectors is much higher than the rated pressure of 4.5 MPa, and the optimal connectors don’t leak under the bending moment of 52.2 kN·m.This research provides the formulation to solve contact pressure on the sealing surface and a structure optimization method to design the connectors with various dimensions.
文摘Halloysite nanotubes were used as nanocontainers to hold corrosion inhibitors such as Ce^(3+)-Zr^(4+),2-mercaptobenzothiazole and 8-hydroxyquinoline in their lumen.An acid assisted etching of the nanotubes was carried out with a view to increase the lumen diameter and thereby,increase the amount of loading of the corrosion inhibitor.The morphology of as-received and etched halloysite nanotubes was ob-served using TEM analysis.The loading of corrosion inhibitors was confirmed using SEM-EDS and BET analysis.Polymeric microcapsules were used as capping agents for the ends of the loaded HNTs following which,they were dispersed into a hybrid sol-gel silica matrix.Dip coating method was used to generate coatings on AZ91D substrates followed by heat treatment at 130℃ for 1 h.The release rate kinetics of corrosion inhibitors from as-received and etched nanotubes was investigated in buffer solutions of 3.5 wt%NaCl at different pH.The release mechanism of corrosion inhibitors from the HNT lumen was validated using various semi-empirical models.Coatings were also evaluated for their corrosion protection ability using electrochemical techniques after exposure to 3.5 wt%NaCl solution for 120 h.Coatings generated using Ce^(3+)-Zr^(4+)loaded into as-received halloysite nanotubes have shown more effective corrosion protection when compared to other corrosion inhibitors after 120 h exposure to the corrosive medium.
文摘The neutral zinc sulfate solution obtained from hydrometallurgical process of Angouran zinc concentrate has cadmium, nickel and cobalt impurities, that must be purified before electrowinning. Therefore, cadmium and nickel are usually cemented out by addition of zinc dust and remained nickel and cobalt cemented out at second stage with zinc powder and arsenic trioxide. In this research, a new approach is described for determination of effective parameters and optimization of zinc electrolyte hot purification process using statistical design of experiments. The Taguchi method based on orthogonal array design（OAD） has been used to arrange the experimental runs. The experimental conditions involved in the work are as follows： the temperature range of 70-90 ℃ for reaction temperature（T）, 30-90 min for reaction time（t）, 2-4 g/L for zinc powder mass concentration（M）, one to five series for zinc dust particle size distributions（S1-S5）, and 0.1-0.5 g/L（C） for arsenic trioxide mass concentration. Optimum conditions for hot purification obtained in this work are T4（85 ℃）, t4=75 min, M4=3.5 g/L, S4（Serie 4）, and C2=0.2 g/L.
基金Project supported by BRICSSTI Framework Program for Basic Research(RFBR-BRICS)(17-52-80072)DST-BRICS,and the State Assignment of Ministry of Science and Education of Russia(topic “Magnet)(AAAA-A18-118020290129-5)
文摘Behavior of the coercivity of the high-temperature Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was investigated.It is shown that the growth rate of coercivity abruptly increases at the initial stage of annealing in the vicinity of the Curie temperature of the SmCo5 phase.The origin of the effect is the counter diffusion of Cu and Co atoms through dislocation tubes,which form because of enhanced stresses and a partial breakage of coherent coupling at the interface of the Sm2 Co17 and SmCo5 phases.Diffusive enrichment of the SmCo5 phase in Cu close to the interface with Sm2 Co17 leads to relaxation of stresses and increases in the gradient of the magnetic domain-wall energy and coercivity.
文摘This study investigated the hot corrosion performance of a dissimilar weldment of Ni-based superalloy and stainless steel joined by CO2-laser welding and improved by high-velocity oxy-fuel(HVOF)coating in a Na2SO4-60wt%V2O5 environment at 900℃.A dissimilar butt joint of AISI 321 and alloy 825 was fabricated by CO2-laser welding with low heat input after obtaining the optimum welding parameters by bead-on-plate trials.The metallurgical and mechanical properties of the laser weldment were evaluated.The tensile test results indicated the occurrence of fracture in the base metal AISI 321 side.The HVOF process was employed to coat Ni-20wt%Cr on the weldment.To evaluate the surface morphology of the corrosion products formed on the uncoated and Ni-20wt%Cr-coated weldments,scanning electron microscopy(SEM)analysis was performed.Energy-dispersive spectroscopy(EDS)was used to determine the different elements present on the surface scales.The existence of oxide phases on the weldments was determined by X-ray diffraction(XRD).The cross sections of the weldments were characterized by SEM with EDS line mapping analysis.The results indicated that the Ni-20wt%Cr-coated weldment exhibited superior hot corrosion resistance due to the development of Cr2O3 and NiCr2O4 protective oxide scales.
文摘High-efficiency perovskite solar cells（PSCs） reported hitherto have been mostly prepared in a moisture and oxygen-free glove-box atmosphere, which hampers upscaling and real-time performance assessment of this exciting photovoltaic technology. In this work, we have systematically studied the feasibility of allambient-processing of PSCs and evaluated their photovoltaic performance. It has been shown that phasepure crystalline tetragonal MAPbI;perovskite films are instantly formed in ambient air at room temperature by a two-step spin coating process, undermining the need for dry atmosphere and post-annealing.All-ambient-processed PSCs with a configuration of FTO/TiO;/MAPbI;/Spiro-OMeTAD/Au achieve opencircuit voltage（990 mV） and short-circuit current density（20.31 mA/cm;） comparable to those of best reported glove-box processed devices. Nevertheless, device power conversion efficiency is still constrained at 5% by the unusually low fill-factor of 0.25. Dark current–voltage characteristics reveal poor conductivity of hole-transporting layer caused by lack of oxidized spiro-OMe TAD species, resulting in high seriesresistance and decreased fill-factor. The study also establishes that the above limitations can be readily overcome by employing an inorganic p-type semiconductor, copper thiocyanate, as ambient-processable hole-transporting layer to yield a fill-factor of 0.54 and a power conversion efficiency of 7.19%. The present findings can have important implications in industrially viable fabrication of large-area PSCs.
文摘Multiwalled carbon nanotubes （MWCNTs） reinforced Cu-Sn alloy based nanocomposite was developed by powder metallurgy route. The mass fraction of CNTs was varied from 0 to 2% in a step of 0.5%. The developed nanocomposites were subjected to density, hardness, electrical conductivity, and friction and wear tests. The results reveal that the density of nanocomposite decreases with the increase of the mass fraction of CNTs. A significant improvement in the hardness is noticed in the nanocomposite with the addition of CNTs. The developed nanocomposites show low coefficient of friction and improved wear resistance when compared with unreinforced alloy. At an applied load of 5 N, the coefficient of friction and wear loss of 2%CNTs reinforced Cu-Sn alloy nanocomposite decrease by 72% and 68%, respectively, compared with those of Cu-Sn alloy. The wear mechanisms of worn surfaces of the composites are reported. In addition, the electrical conductivity reduces with the increase of the content of CNTs.
