Nonlinear Absorption and Low-threshold Two-photon Pumped Amplified Stimulated Emission from FAPbBr_(3) Nanocrystals

Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.However,two-photon pumped amplified spontaneous emission(ASE)and the corresponding nonlinear optical properties of FAPbBr_(3) NCs are scarcely revealed.Herein,we synthesized colloidal FAPbBr_(3) NCs with different sizes by changing the molar ratio of FABr/PbBr_(2) in the precursor solution,using ligand assisted precipitation(LARP)technology at room temperature.Photoluminescence(PL)and time resolved photoluminescence(TRPL)spectroscopy were measured to characterize their ASE properties.And their nonlinear optical properties were studied through the Zscan technique and the two-photon excited fluorescence method.The stimulated emission properties including oneand two-photon pumped ASE have been realized from FAPbBr_(3) NCs.With large two-photon absorption coefficient(0.27 cm/GW)and high non-linear absorption cross-section(7.52×10^(5) GM),ASE with threshold as low as 9.8μJ/cm^(2) and 487μJ/cm^(2) have been obtained from colloidal FAPbBr_(3) NCs using one-and two-photon excitations.These results indicate that as a new possible green-emitting frequency-upconversion material with low thresholds,FAPbBr_(3) NCs hold great potential in the development of high-performance two-photon pump lasers.

Prospects for green steelmaking technology with low carbon emissions in China

The steel industry is a major source of CO_(2) emissions,and thus,the mitigation of carbon emissions is the most pressing challenge in this sector.In this paper,international environmental governance in the steel industry is reviewed,and the current state of development of low-carbon technologies is discussed.Additionally,low-carbon pathways for the steel industry at the current time are proposed,emphasizing prevention and treatment strategies.Furthermore,the prospects of low-carbon technologies are explored from the perspective of transitioning the energy structure to a“carbon-electricity-hydrogen”relationship.Overall,steel enterprises should adopt hydrogen-rich metallurgical technologies that are compatible with current needs and process flows in the short term,based on the carbon substitution with hydrogen(prevention)and the CCU(CO_(2) capture and utilization)concepts(treatment).Additionally,the capture and utilization of CO_(2) for steelmaking,which can assist in achieving short-term emission reduction targets but is not a long-term solution,is discussed.In conclusion,in the long term,the carbon metallurgical process should be gradually supplanted by a hydrogen-electric synergistic approach,thus transforming the energy structure of existing steelmaking processes and attaining near-zero carbon emission steelmaking technology.

Numerical modeling techniques for noise emission of free railway wheels

In this article,we consider the numerical prediction of the noise emission from a wheelset in laboratory conditions.We focus on the fluid-structure interaction leading to sound emission in the fluid domain by analyzing three different methods to account for acoustic sources.These are a discretized baffled piston using the discrete calculation method(DCM),a closed cylindrical volume using the boundary element method(BEM)and radiating elastic disks in a cubic enclosure solved with the finite element method(FEM).We provide the validation of the baffled piston and the BEM using measurements of the noise emission of a railway wheel by considering ground reflections in the numerical models.Selected space-resolved waveforms are compared with experimental results as well as with a fluid-structure interaction finite element model.The computational advantage of a discretized disk mounted on a baffle and BEM compared to FEM is highlighted,and the baffled pistons limitations caused by a lack of edge radiation effects are investigated.

Shear band evolution and acoustic emission characteristics of sandstone containing non-persistent flaws

Direct shear tests were conducted on sandstone specimens under different constant normal stresses to study the coalescence of cracks between non-persistent flaws and the shear sliding characteristics of the shear-formed fault.Digital image correlation and acoustic emission(AE)techniques were used to monitor the evolution of shear bands at the rock bridge area and microcracking behaviors.The experimental results revealed that the shear stresses corresponding to the peak and sub-peak in the stressdisplacement curve are significantly affected by the normal stress.Strain localization bands emerged at both the tip of joints and the rock bridge,and their extension and interaction near the peak stress caused a surge in the AE hit rate and a significant decrease in the AE b value.Short and curvilinear strain bands were detected at low normal stress,while high normal stress generally led to more microcracking events and longer coplanar cracks at the rock bridge area.Furthermore,an increase in normal stress resulted in a higher AE count rate and more energetic AE events during friction sliding along the shearformed fault.It was observed that the elastic energy released during the crack coalescence at the prepeak stage was much greater than that released during friction sliding at the post-peak stage.More than 75%of AE events were located in the low-frequency band(0e100 kHz),and this proportion continued to rise with increasing normal stress.Moreover,more AE events of low AF value and high RA value were observed in specimens subjected to high normal stress,indicating that greater normal stress led to more microcracks of shear nature.

Synergistic dance of digital economy and green finance on carbon emissions:Insights from China

China has recently implemented a dual-carbon strategy to combat climate change and other environmental issues and is committed to modernizing it sustainably.This paper supports these goals and explores how the digital economy and green finance intersect and impact carbon emissions.Using panel data from 30 Chinese provinces over the period 2011-2021,this paper finds that the digital economy and green finance can together reduce carbon emissions,and conducts several robustness tests supporting this conclusion.A heterogeneity analysis shows that these synergistic effects are more important in regions with low levels of social consumption Meanwhile,in the spatial dimension,the synergistic effect of the local digital economy and green finance adversely impacts the level of carbon emissions in surrounding areas.The findings of this paper provide insights for policymakers in guiding capital flow and implementing carbon-reduction policies while fostering the growth of China’s digital economy and environmental sustainability.

Rim^(18)F-fluorodeoxyglucose uptake of hepatic cavernous hemangioma on positron emission tomography/computed tomography:A case report

BACKGROUND Peripheral FDG accumulation in a hepatic hemangioma presenting in a patient with prolonged fever is rare.Therefore,clinicians should pay close attention to patients with hepatic mass.CASE SUMMARY A 54-year-old woman with a 4-wk history of daily fevers was admitted to our hospital.A whole body^(18)-Fluordesoxyglucose(PET-FDG)positron emission tomography/computed tomography(PET/CT)was performed to elucidate the source of the fever.However,whole body^(18)-FDG PET/CT raised the suspicion of a malignant lesion because of peripheral FDG accumulation(SUVmax 3.5 g/mL)higher than that of the normal liver parenchyma(SUVmax 1.6 g/mL)surrounding a hypoactive area,and no other abnormalities were showed.Subsequently,the patient underwent liver mass resection.Histopathology showed a hepatic cavernous hemangioma with fatty infiltration around the lesion.The fever disappeared four days after surgery and the patient did not present any complications during follow-up.CONCLUSION Fatty infiltration in the peripheral parts of hepatic cavernous hemangioma may lead to subacute inflammation which further activate the Kupffer cells.This may cause prolonged fever and peripheral rim FDG accumulation on PET/CT.

A dual-route optical emission spectroscopy diagnostic with wide spectral range and high wavelength resolution on HL-2A tokamak

A dual-route optical emission spectroscopy(D-OES)diagnostic is newly developed to monitor the optical emission from the X-point plasma region on the HL-2 A tokamak.This diagnostic is composed of an imaging system,a beam-splitting system for dual-route measurements,fiber bundles,a spectrometer system,and a control and acquisition system.One route is used to obtain wide-spectral-range spectra,and the other route is used to acquire high-wavelengthresolution line shapes.The spectral resolution of the wide-range spectrometers is 0.8 nm with a coverage of 800 nm(@200-1000 nm).The spectral resolution of the high-resolution spectrometer is 0.01 nm with a coverage of 6 nm(@200-660 nm).The spatial resolution of each route of D-OES is about 4 cm with 11 channels.The temporal resolution is 16 ms at maximum in the single-channel mode.Wide-range spectra(containing Balmer series and a Fulcher band)and highly resolved Ha line shapes are obtained by D-OES in the hydrogen glow discharge in the lab.D-OES measurements are carried out in the high-density deuterium experiments of HL-2A.The electron density n_(e)and deuterium temperature T_(D) in the X-point multifaceted asymmetric radiation from the edge(MARFE)region are derived simultaneously by fitting the measured D_(a) shape.The density n_(e)is observed to increase from~8.7×10^(18)m^(-3)to~7.8×10^(19)m^(-3),and the temperature T_(D)drops from~14.4 eV to~2.3 eV after the onset of MARFE in the discharge#38260.

Exploring the impact of economic growth and energy consumption on SO_(2) emissions in China based on the Environmental Kuznets Curve hypothesis

This study aims to analysis the influence of economic growth(EG)and energy consumption(EC)on sulfur dioxide emissions(SE)in China.Accordingly,this study explores the link between EG,EC,and SE for 30 provinces in China over the span of 2000-2019.This study also analyzes cross-sectional dependence tests,panel unit root tests,Westerlund panel cointegration tests,Dumitrescu-Hurlin(D-H)causality tests.According to the test results,there is an inverted U-shaped association between EG and SE,and the assumption of the Environmental Kuznets Curve(EKC)is verified.The signs of EG and EC in the fixed effect(FE)and random effect(RE)methods are in line with those in the dynamic ordinary least squares(DOLS),fully modified ordinary least squares(FMOLS)and autoregressive distributed lag(ARDL)estimators.Moreover,the results verified that EC can obviously positive impact the SE.To reduce SE in China,government and policymakers can improve air quality by developing cleaner energy sources and improving energy efficiency.This requires the comprehensive use of policies,regulations,economic incentives,and public participation to promote sustainable development.

Design of the electron cyclotron emission diagnostic on EXL-50 spherical torus

The electron cyclotron emission(ECE)diagnostic system has been developed on the ENN spherical torus(EXL-50).The ECE system is designed to detect radiation emitted by energetic electrons,rather than conventional 1D electron temperature profile measurement,in the frequency range of 4-40 GHz.The system is composed of five subsystems,each covering a different frequency band,including the C-band(4-8 GHz),X-band(8-12 GHz),Ku-band(12-18 GHz),K-band(18-26.5 GHz)and Kα-band(26.4-40 GHz).The system uses heterodyne detection to analyze the received signals.The K-band and Kα-band subsystems are located horizontally in the equatorial plane of the EXL-50,while the C-band,X-band and Ku-band subsystems are located under the vacuum vessel of the EXL-50.To direct the microwaves from the plasma to the antennas for the horizontal detection subsystems,a quasi-optical system has been developed.For the vertical detection subsystems,the antennas are directly attached to the port located beneath the torus at R=700 mm,which is also the magnetic axis of the torus.The system integration,bench testing and initial experimental results will be thoroughly discussed,providing a comprehensive understanding of the ECE system s performance and capabilities.

Nonlinear change of ion-induced secondary electron emission in theκ-Al_(2)O_(3) surface charging from first-principle modelling

Secondary electron emission(SEE)induced by the positive ion is an essential physical process to influence the dynamics of gas discharge which relies on the specific surface material.Surface charging has a significant impact on the material properties,thereby affecting the SEE in the plasma-surface interactions.However,it does not attract enough attention in the previous studies.In this paper,SEE dependent on the charged surface of specific materials is described with the computational method combining a density functional theory(DFT)model from the first-principle theory and the theory of Auger neutralization.The effect ofκ-Al2O3 surface charge,as an example,on the ion-induced secondary electron emission coefficient(SEEC)is investigated by analyzing the defect energy level and band structure on the charged surface.Simulation results indicate that,with the surface charge from negative to positive,the SEEC of a part of low ionization energy ions(such as Ei=12.6 eV)increases first and then decreases,exhibiting a nonlinear changing trend.This is quite different from the monotonic decreasing tendency observed in the previous model which simplifies the electronic structure.This irregular increase of the SEEC can be attributed to the lower escaped probability of orbital energy.The results further illustrate that the excessive charge could cause the bottom of the conduction band close to the valence band,thus leading to the decrease of the orbital energy occupied by the excited electrons.The nonlinear change of SEEC demonstrates a more realistic situation of how the electronic structure of material surface influences the SEE process.This work provides an accurate method of calculating SEEC from specific materials,which is urgent in widespread physical scenarios sensitive to surface materials,such as increasingly growing practical applications concerning plasma-surface interactions.

Guiding function of positron emission tomographycomputed tomography examination in the diagnosis and treatment of ocular adnexal mucosa associated lymphoid tissue lymphoma

AIM:To explore the role of positron emission tomographycomputed tomography(PET-CT)examination in the diagnosis and treatment of ocular adnexal mucosa associated lymphoid tissue lymphoma(OAML).METHODS:The general clinical data,postoperative PET-CT results,treatment regimens,and the prognosis of 21 histopathologically confirmed OAML patients between October 2017 and September 2021 were collected.Among the 21 patients,five patients underwent surgical treatment alone,13 patients underwent surgical treatment combined with radiotherapy,and three patients underwent surgical treatment combined with chemotherapy.RESULTS:The follow-up period ranged from 8 to 79mo,with four cases of recurrence and no deaths.Through PETCT examination,two patients exhibited both local ocular metabolic elevation and systemic metastasis,and one of these patients had cervical lymph node metastasis,while the other had submandibular and parotid gland metastasis.Nine patients showed only local ocular metabolic elevation,while 10 patients had no abnormal metabolic activity locally.CONCLUSION:PET-CT examination plays a crucial role in detecting residual lesions and recurrence following tumor resection,aiding in precise disease staging,and facilitating the development of personalized treatment plans,ultimately improving patient prognosis.

Highly stable Ga-doped ZnO/polystyrene nanocomposite film with narrow-band cyan emission

In the present study,a simple method for the preparation of a luminescent flexible gallium doped zinc oxide(GZO)/polystyrene nanocomposite film was developed.The prepared GZO powder was characterized through different optical and structural techniques.The XRD study revealed the existence of a wurtzite structure with no extra oxide peaks.Elemental-mapping,EDX,FTIR and XPS analyses were used to confirm the presence of elements and the several groups present in the structure.Under excitations of UV,the prepared hybrid nanocomposite showed a strong cyan emission with narrow full width at half the maximum value(20 nm)that has not been reported before.X-ray and laser-induced luminescence results of the hy-brid film revealed novel blue-green emission at room temperature.The prepared composite film showed a strong scintillation re-sponse to ionizing radiation.The strong emissions,very weak deep-level emissions,and low FWHM of composite indicate the de-sirable optical properties with low-density structural defects in the GZO composite structure.Therefore,the prepared hybrid film can be considered to be a suitable candidate for the fabrication of optoelectronic devices.

Influence of Pretreatment Conditions of Stainless Steel Substrates on Field Emission Properties of Carbon Nanotubes Films

Carbon nanotubes (CNTs) are synthesized from methane and hydrogen gas mixture directly on stainless steel plates by microwave plasma chemical vapor deposition (MWPCVD).By varying pretreatment conditions of the substrates such as mechanically polishing and acid washing,it is found the polishing and acid washing can lower the turn-on field and improve the emission current density.The current density of the un-pretreated sample attains 1.2mA/cm 2,but the polished sample and polished acidly washed sample attain 3.2 and 2.75mA/cm 2,respectively,at the electric field of 6.25V/μm.

Field Emission from a Mixture of Amorphous Carbon and Carbon Nanotubes Films

A mixture of amorphous carbon and carbon nanotubes films was synthesized on stainless steel plates by a micro- wave plasma enhanced chemical vapor deposition system. The source gases were hydrogen and methane with flow rates of 100 and 16sccm,respectively,with a total pressure of 5.0kPa. The surface morphology and the structure of the films were characterized by field emission scanning electron microscopy （SEM） and Raman scattering spectroscopy. Field emission properties of as-deposited film were measured in a vacuum room below 5 ×10^ 5 Pa. The experimental results show that the initial turn-on field is 0. 9V/μm; The current density is 4.0mA/cm2 and the emission sites are dense and uniform at an electric field of 3.7V/μm. These results indicate that such a mixture of amorphous carbon and carbon nanotubes films is a promising material for field emission applications.

Effects of Reduced Nitrogen Fertilization and Biochar Application on CO_2 and N_2O Emissions from a Summer Maize-Winter Wheat Rotation Field in North China

This experiment was conducted in Xinxiang, Henan from June 2013 to June 2014. Total four treatments were designed including farmers ’ common practice （F, 250 kg/hm^2）, 80% F （LF, 200 kg/hm^2）, 80% F＋biochar （LFC） and no fertilizer （CK） to measure the dynamic emissions of CO2 and N2O from a summer maize-winter wheat field by static chamber-gas chromatography method. The results showed that the soil CO2 emission was 21.8-1 022.7 mg/（m^2·h）, and was mainly influenced by soil temperature and moisture content. During the growth of summer maize, the soil CO2 emission was more significantly affected by soil moisture con-tent; and in winter wheat growing season, it was more significantly affected by soil temperature in the top 5 cm. The LF and LFC treatments significantly reduced the soil cumulative CO2 emission, especial y during the growth of winter wheat. Fertiliza-tion and irrigation were the main factors influencing the soil N2O emission. The soil N2O emission during the fertilization period accounted for 73.9%-74.5% and 40.5%-43.6% of the soil cumulative N2O emission during the summer maize-and winter wheat-growing season, respectively. The peak of emission fluxes was determined by fertilization amount, while the occurrence time of emission peak and emission re-duction effect were influenced by irrigation. The LF treatment reduced the soil cu-mulative N2O emission by 15.7%-16.8% and 18.1%-18.5% during the growth period of summer maize and winter wheat, respectively. Reduced nitrogen fertilization is an effective way for reducing N2O emission in intensive high-yielding farmland. Under a suitable nitrogen level （200 kg/hm^2）, the application of biochar showed no significant effect on the soil N2O emission in a short term. The N2O emission factors of the L and LF treatments were 0.60% and 0.56%, respectively. ln the intensive high-yield-ing farmland of North China, reducing the nitrogen application amount is an appro-priate measure to mitigate greenhouse gas emissions without crop yield loss.

Non-cropping period accounting for over a half of annual nitric oxide releases from cultivated calcareous-soil alpine ecosystems with marginally low emission factors

Nitric oxide(NO)emissions from alpine ecosystems conventionally being long-term cultivated with feed crops are not well quantified.The authors attempted to address this knowledge gap by performing a year-round experimental campaign in the northeastern Tibetan Plateau.Fertilized(F)and unfertilized(UF)treatments were established within a flat calcareous-soil site for the long-term cultivation of feed oats.NO fluxes and five soil variables were simultaneously measured.A single plow tillage accounted for approximately 54%–73%of the NO releases during the cropping period(CP);and the non-cropping period(NCP)contributed to 51%–58%of the annual emissions.The direct NO emissions factor(EFd)was 0.021%±0.021%.Significantly lower Q10 values(p<0.01)occurred in the F treatment during the CP(approximately 3.6)compared to those during the other period or in the other treatment(approximately 4.9?5.1),indicating a fertilizer-induced reduction in the temperature sensitivity.The selected soil variables jointly accounted for up to 72%(p<0.01)of the variance for all the fluxes across both treatments.This finding suggests that temporally and/or spatially distributed fluxes from alpine calcareous-soil ecosystems for feed crop production may be easily predicted if data on these soil variables are available.Further studies are needed to test the hypothesis that the EFd is larger in alpine feed-oat fields than those in this study if the soil moisture content is higher during the period following the basal application of ammoniumor urea-based fertilizer.

Fabrication and Field Emission of Silicon Nano-Crystalline Film

The silicon nano-crystalline (nc-Si) film is fabricated on <100> orientation,0.01Ω·cm resistivity,and p-type boron-doped silicon wafer by the anodic etching.The microstructure and the orientation of nc-Si are examined by the scanning electron microscopy,transmission electron microscopy,and X-ray diffraction spectroscopy,respectively.The average size of particle is estimated by Raman spectroscopy.The results show that the particle size of nc-Si film is scattered from 10nm to 20nm,the alignment is compact,the orientation is uniform,the expansion of lattice constant is negligible,and mechanical robustness and stability are good.The correlations between film structure and the experiment parameters such as etching time,HF concentration,and etching current density are discussed.As a potential application,efficient field emission is observed from the nc-Si film,and the turn-on field is about 3V/μm at 0.1μA/cm 2 of current density,which is close to carbon nanotube film's.

Methane and Nitrous Oxide Emissions from Rice-Duck and Rice-Fish Complex Ecosystems and the Evaluation of Their Economic Significance

Rice-duck （RD） and rice-fish （RF） ecological systems are major complex planting and breeding models of rice paddy fields in southern China. Studying the methane （CH4） and nitrous oxide （N2O） emissions and their economic value from these two ecosystems can provide theoretical and practical basis for further development and utilization of these classical agricultural techniques. CH4 and N2O emissions from RD and RF ecological systems were measured in situ by using static chambers technique. Using global warming potentials （GWPs）, we assessed the greenhouse effect of CH4 and N2O and their economic value. Results showed that the peaks of CH4 emission fluxes from RD and RF appeared at full tillering stage and at heading stage, and the average emission fluxes were significantly （P〈 0.05） lower than that from CK. N2O fluxes remained low when the field is flooded and high after draining the water. Compared with CK, the total amount of N2O emissions was significantly （P〈0.05） higher and slightly lower than those from RD and RF, respectively. In 2006 and 2007, the total greenhouse effect of CH4 and N20 from RD and RF were 4 728.3 and 4 611 kg CO2 ha^-1, 4 545 and 4 754.3 kg CO2 ha^-1, respectively. The costs of greenhouse effect were 970.89 and 946.81 RMB yuan ha^-1, and 933.25 and 976.23 RMB yuan ha^-1, respectively, which were significant lower than those from CK （5 997.6 and 5 391.5 RMB yuan ha^-1）. Except for the environment cost of CH4 and N2O, the economic benefits from RD and RF were 2 210.64 and 4 881.92 RMB yuan ha^-1; 3 798.37 and 5 310.64 RMB yuan ha^-1, respectively, higher than those from CK. Therefore, RD and RF complex ecological planting and breeding models can effectively decrease and control CH4 and N2O emissions, and they are two of the effective strategies to reduce greenhouse gases from rice paddy fields and contribute in alleviating global warming. Thus, their adoption is important to the environment together with their economy benefits.

Advanced Technologies for Volatile Organic Compound (VOC) Emission Treatment: An Overview

This paper presents a comprehensive overview of various advanced technologies employed in the treatment of volatile organic compounds(VOCs),which are crucial pollutants in industrial emissions.The study explores different methods,including direct combustion,thermal combustion,catalytic combustion,low-temperature plasma purification,photocatalytic purification,membrane separation,and adsorption methods.Each technology is critically analyzed for its operational principles,efficiency,and applicability under different conditions.Special attention is given to adsorption concentration and catalytic combustion parallel method,highlighting its efficiency in treating low-concentration,high-volume VOC emissions.The paper also delves into the advantages and limitations of each method,providing insights into their effectiveness in various industrial scenarios.The study aims to offer a detailed guide for selecting appropriate VOC treatment technologies,contributing to enhanced environmental protection and sustainable industrial practices.

Studies on Technique of Reducing Methane Emission in a Rice-Duck Ecological System and the Evaluation of Its Economic Significance

The rice-duck ecological system is one of the major practices of the traditional Chinese agriculture. A study on the effect of reducing methane emission using this practice provided theoretical and practical basis for further development and utilization of this classical agricultural technique. The effect of reducing methane emission and the economic benefits of rice-duck ecological system were studied by carrying out a field experiment and by using economic methodology. The daily variation of CH4 emission in late rice paddy field was basically consistent with the daily variation of atmospheric temperature. The highest emission occurred at the full tillering stage of late rice with a rate of 24.1 or 32.2 or 40.5 mg m^-2 h^-1 in no-tillage area with duck and no-tillage area without duck and conventional-tillage area without duck, respectively. The inhibition of methane emission was apparently effective in the rice-duck ecological system during the initial tillering stage and the full tillering stage. Compared to the no-tillage area without duck, methane emission decreased by 2.333 g m^-2. Compared to the conventional-tillage area without duck, methane emission decreased by 4.723 g m^-2. During the production period of late rice, the amount of methane emission in no-tillage area with duck was 3.373 g m^-2 lesser than that of no-tillage area without duck, and 5.59 g m^-2 less than that of conventional-tillage without duck area. The economic significance was analyzed. Farmers adopting the rice-duck ecological system obtained 2 166 and 4 207 RMB yuan ha^-1 more income than those who adopted a no-tillage without duck technique or conventional-tillage without duck technique, respectively. In addition to the reduction of the environmental pollution by methane emission, the farmers who adopted the rice-duck ecological system achieved economic benefits of 5 000 RMB yuan ha^-1, which was 2 206 and 4 274 RMB yuan ha^-1 more than those who adopted a no-tillage without duck technique and a conventional-tillage without duck technique, respectively. The rice-duck ecological system not only increased the economic benefits for farmers, but also reduced methane emission in rice paddy field. A sustainable agricultural production mode was formed.