Transitional metal alloy and compounds have been developed as the low cost and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,a high mass loading o...Transitional metal alloy and compounds have been developed as the low cost and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,a high mass loading of these catalysts is commonly needed to achieve acceptable catalytic performance,which could cause such problems as battery weight gain,mass transport blocking,and catalyst loss.We report herein the preparation of fine CoNi nanoparticles(5-6 nm)anchored inside a nitrogendoped defective carbon nanotube network(CoNi@N-DCNT)by a transient Joule heating method.When utilized as an electrocatalyst for oxygen reduction and evolution in alkaline media,the CoNi@N-DCNT film catalyst with a very low mass loading of 0.06 mg cm^(-2) showed excellent bifunctional catalytic performance.For ORR,the onset potential(Eonset)and the half-wave potential(E_(1/2))were 0.92 V versus reversible hydrogen electrode(vs.RHE)and 0.83 V(vs.RHE),respectively.For OER,the potential at the current density(J)of 10 mA cm^(-2)(E_(10))was 1.53 V,resulting in an overpotential of 300 mV much lower than that of the commercial RuO_(2) catalyst(320 mV).The potential gap between E_(1/2) and E_(10) was as small as 0.7 V.Considering the low mass loading,the mass activity at E_(10) reached at 123.2 A g^(-1),much larger than that of the RuO_(2) catalyst and literature results of transitional metal-based bifunctional catalysts.Moreover,the CoNi@N-DCNT film catalyst showed very good long-term stability during the ORR and OER test.The excellent bifunctional catalytic performance could be attributed to the synergistic effect of the bimetal alloy.展开更多
The hydroarylation reaction of terminal alkynes with arylboronic acids catalyzed by low(400 ppm) loadings of palladium has been developed. The reaction is broad in scope and high-yielding, even on multigram scale. It ...The hydroarylation reaction of terminal alkynes with arylboronic acids catalyzed by low(400 ppm) loadings of palladium has been developed. The reaction is broad in scope and high-yielding, even on multigram scale. It is suitable for the synthesis of alkenes labeled with deuterium, and for the late-stage modification of bioactive molecules.展开更多
The very long tradition of the activated sludge treatment model within the water industry has demonstrated very versatile possibilities to adopt the operation mode for different enhancements. By looking into other tre...The very long tradition of the activated sludge treatment model within the water industry has demonstrated very versatile possibilities to adopt the operation mode for different enhancements. By looking into other treatment models within the activated sludge family it is possible to find alternatives for the operation. This paper concentrates on the possibilities to improve even small WWTP with respect to energy savings. The small plant in Northern Sweden, called Rosvik WWTP, is given as an example. Some important findings related to the intermittent aeration mode may be summarized as follows: 1) An energy savings for the operation of the small WWTP with respect to aeration needs that resulted in a decrease of the energy power supply by more than 35%, as compared with the previous operation based on continuous aeration;2) The up to date effluent levels with respect to the main pollutants have remained at very good levels in 2020, P-level averages 0.16 mg P/l versus consent level <</span><span> </span><span style="font-family:Verdana;">0.5 mg P/l;COD-level 40 versus <</span><span> </span><span><span style="font-family:Verdana;">70 mg/l and BOD</span><sub><span style="font-family:Verdana;">7</span></sub><span style="font-family:Verdana;"> 9 versus <</span></span><span> </span><span><span style="font-family:Verdana;">15 mg/l;3) Sometimes, also improved sludge settling characteristics have been observed, thus providing improved discharge figures;4) The potential to develop an enhanced biological phosphorus removal. There are however </span><span style="font-family:Verdana;">some needed conditions to accomplish these improvements: 1) Reliable</span><span style="font-family:Verdana;"> on-line probes for both oxygen control, SS-concentration control and optionally also for nitrogen control;2) A flexible automation system that allows the needed process modifications to take place;3) And finally, very important dedicated and competent plant operators, with the needed curiosity for operation improvements.展开更多
The Sri Lankan national water authority, that is The National Water Supply and Drainage Board (NWS&DB) has taken a new wastewater treatment plant into operation at Ja Ela, North of Colombo. The plant has been in o...The Sri Lankan national water authority, that is The National Water Supply and Drainage Board (NWS&DB) has taken a new wastewater treatment plant into operation at Ja Ela, North of Colombo. The plant has been in operation since September 2011. In April 2012, it was concluded how a test of the aeration efficiency and a performance test should be carried out. The tests have been based on the actual loading of the plant and the analysis results from the daily process control. The evaluation of the aeration efficiency is not reported in this paper. The paper presents the overall performance of the water treatment part of the plant during start-up conditions, from fall 2011 through the first five months of 2012. The results from the operation are found in Table 1. An important circumstance at the plant is the current very low loading in comparison with the design load. This fact has resulted in an introduction of an intermittent mode of the aeration (nitrification) reactor. Based on operation figures, during more than a month (May 2012), it has been possible to give a realistic assessment of the overall performance. The most striking results are summarized as follows: 1) The intermittent operation has enabled an energy efficient operation of the plant. By the introduction of the intermittent aeration, the energy consumption has been reduced by around 75%, compared with the continuous operation mode;2) The plant performance during the intermittent operation has been improved with respect to virtually all important pollution variables. The most striking improvement is the discharge total P level, reflecting that a substantial enhanced biological phosphorus removal takes. The typical discharge levels found during May 2012, were compared with the earlier obtained values. It is important to underline that the loading on the plant has slightly increased during May as compared with the previous operation period.展开更多
Tests of nine angle-steel concrete column （ASCC） specimens under low cyclic loading are described in a companion paper （Zheng and Ji, 2008）. In this paper, the skeleton curves from the numerical simulation are pre...Tests of nine angle-steel concrete column （ASCC） specimens under low cyclic loading are described in a companion paper （Zheng and Ji, 2008）. In this paper, the skeleton curves from the numerical simulation are presented, and show good agreement with the test results. Furthermore, parametric studies are conducted to explore the influence of factors such as the axial compression ratio, shear steel plate ratio, steel ratio, prismatic concrete compression strength, yield strength of angle steel and shear span ratio, etc., on the monotonic load-displacement curves of the ASCCs. Based on a statistical analysis of the calculated results, hysteretic models for load-displacement and moment-curvature are proposed, which agree well with the test results. Finally, some suggestions concerning the conformation of ASCCs are proposed, which could be useful in engineering practice.展开更多
The ballistic properties of a low solid loading composite solid propellant family （Butalites） was studied experimentally by using propellant formulations based on hydroxy-terminated polybutadiene pre-polymer （HTPB...The ballistic properties of a low solid loading composite solid propellant family （Butalites） was studied experimentally by using propellant formulations based on hydroxy-terminated polybutadiene pre-polymer （HTPB） as fuel binder main backbone, mono and bi-modal system ammonium perchlorate oxidizer （AP）, copper chromite （CC） as burning rate accelerator and aluminum powder （A1） as metallic fuel. Higher pressures and AP contents as well as smaller AP particle size were found to increase burning rate. The same behavior verified with AI and CC addition. A significant increase of burning rate was recorded when CC added to the aluminized formulations compared with the non-aluminized of the same oxidizer solid loading and particle size.展开更多
There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to u...There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to use high performance lightweight materials.The former method takes very few considerations on the structural strengthening effects caused by the massive small loads in service.In order to ensure safety,the design is usually conservative,but the strength potential of the component is not fully exerted.In the latter method,cost is the biggest obstacle to lightweight materials in automotive applications.For the purpose of light weighting design on a fuel cell vehicle,the new design method is applied on drive shafts.The method is based on the low amplitude load strengthening characteristics of the material,and allows the stress,corresponding to test load,to enter into the strengthened range of the material.Under this condition,the light weighting design should assure that the reliability of the shaft is not impaired,even maximizes the strength potential of machine part in order to achieve the weight reduction and eventually to reduce the cost.At last,the feasibility of the design is verified by means of strength analysis and modal analysis based on the CAD model of light weighted shaft.The design applies to the load case of half shaft in independent axle,also provides technological reference for the structural lightweight design of vehicles and other machineries.展开更多
Tests with middle-crack tension （M（T）） specimens made of Al 2324-T39 and Al 7050-T7451 are conducted to investigate the influence of low load truncation level on fatigue crack growth. The six different truncated s...Tests with middle-crack tension （M（T）） specimens made of Al 2324-T39 and Al 7050-T7451 are conducted to investigate the influence of low load truncation level on fatigue crack growth. The six different truncated spectra are obtained by removing the small cycles of which amplitudes are less than the specified percentages of the maximum amplitude in the basic flight-by-flight loading spectrum and the remainder of the spectrum is untouched. The tests indicate that the mean level of fatigue crack growth life （FCGL） increases as the load truncation level is enhanced. Considering both the time saving and the influence on FCGL, there is an applicable choice （i.e. spectrum S2 or spectrum S3 in this investigation） for full scale fatigue test. The scatter of FCGL becomes much larger than that under the basic spectrum when the load truncation level is increased to a specified high level, mainly due to the occurrence of crack slanting and branching under the high level truncated loading spectra.展开更多
AIM:To assess the efficacy and advantages of 4-wk pegylated interferon a-2a(peg-IFN-a2a) monotherapy for chronic hepatitis C patients with strong predictors of sustained virologic response(SVR).METHODS:Patients(n = 33...AIM:To assess the efficacy and advantages of 4-wk pegylated interferon a-2a(peg-IFN-a2a) monotherapy for chronic hepatitis C patients with strong predictors of sustained virologic response(SVR).METHODS:Patients(n = 33) with genotype 2 and low viral load(< 100 KIU/mL),who became HCV RNA negative after 1 wk of IFN treatment,were randomly allocated to receive a 4-or 12-wk treatment course at a ratio of 2:1,respectively,with a subsequent 24-wk follow-up period.Peg-IFN-a2a was administered subcutaneously at a dose of 180 μg or 90 μg once weekly.SVR was defined as absence of serum HCV RNA at the end of the follow-up period.RESULTS:All patients completed the treatment schedule,and more than half were symptom-free during the treatment.In the 4-wk treatment group,20 of 22(91%) patients achieved SVR.Two patients relapsed,but achieved SVR following re-treatment with peg-IFN-a2a alone.In the 12-wk treatment group,11 of 11(100%) patients attained SVR.CONCLUSION:Our results show that a 4-wk course of peg-IFN-a2a monotherapy can achieve a high SVR rate in "IFN-sensitive" patients,without negatively affecting outcome.展开更多
A palladium catalytic system incorporating novel Fc-JosiPhos ligands enables efficient C–N bond formation with diverse(hetero)aryl halides under low palladium loading(0.1 mol%).We rationally designed novel ferrocenyl...A palladium catalytic system incorporating novel Fc-JosiPhos ligands enables efficient C–N bond formation with diverse(hetero)aryl halides under low palladium loading(0.1 mol%).We rationally designed novel ferrocenyl phosphine-derived JosiPhos ligands(L1–L3).These ligands incorporate a ferrocenyl group providing greater steric bulk than tert-butyl or cyclohexyl and superior electron donation to cyclohexyl,along with a tunable side chain.They delivered excellent yields in the catalytic coupling of challenging(hetero)aryl chlorides with hydrazine.The scalable synthesis of arylhydrazines(5mmol scale)and subsequent cyclization to pyrazoles(65%–91%yields)highlights their potential for industrial conversion.Furthermore,the modularity of this strategy supports late-stage pharmaceutical functionalization,exemplified by TRPC inhibitor intermediate.展开更多
Highly efficient catalysts for electrolysis of water are crucial to the development of hydrogen energy which is helpful to carbon neutralization.Recently,high temperature shock(HTS),with advantage of rapid speed,unive...Highly efficient catalysts for electrolysis of water are crucial to the development of hydrogen energy which is helpful to carbon neutralization.Recently,high temperature shock(HTS),with advantage of rapid speed,universality and scalable production,has been a promising method in synthesis of nanomaterials.In this paper,HST was used to treat low Pt loading Mo_(6)S_(8)for enhanced water splitting performance.Impressively,the optimized MoS_(2)/MoO_(2)/Mo_(6)S_(8)nano-composite with low Pt mass loading(~4%)displays well hydrogen evolution reaction(HER)electrochemical performance.The overpotential is 124 mV to reach 10 mA/cm^(2)and the corresponding Tafel slope is 88 mV/dec in acidic electrolyte.Its mass activity is 6.2 mA/μg_(Pt)at-124 mV vs.RHE,which is almost 2 times relative to 20%Pt/C.Moreover,it presents distinguished stability even after 2000 cycles.This work will broaden the way of catalysts preparation and the application of hydrogen evolution.展开更多
Objective To analyze the clinical characteristics of HBeAg-negative chronic hepatitis B virus(HBV)infection in indeterminate phase with a low viral load.Methods Onehundredd and thirty-nine cases with persistent normal...Objective To analyze the clinical characteristics of HBeAg-negative chronic hepatitis B virus(HBV)infection in indeterminate phase with a low viral load.Methods Onehundredd and thirty-nine cases with persistent normal alanine aminotransferase(ALT)and HBeAg-negative chronic HBV infection with low viral load who visited the Department of Infectious Diseases of the Affiliated Hospital of Yan'an University from September 2013to July 2021 wereretrospectively collected.Patients were divided into low hepatitis B surface antigen(HBsAg)group(n=59)and high HBsAg group(n=80)according to the baseline hepatitis B surface antigen(HBsAg)level.The changes of various indicators at baseline and follow-up endpoints were analyzed between the two groups.The rate of HBsAg decrease≥0.5 logio IU/ml,HBV DNA negative conversion rate,ALT persistently normal rate,and liver stiffness measurement(LSM)persistently normal rate at the end of the follow-up were compared.The t-test,or non-parametric Mann-Whitney U test,and Wilcoxon signed rank test were used for comparison of continuous data between the two groups.The x^(2)test,or Fisher's exact probability method,was used for comparing count data between the two groups.ResultsThere were statistically significant differences in age,gender,and HBsAg at baseline,but therewasnostatistically significant difference in terms of family history of hepatitis B,follow-up time,anti-HBe,anti-HBc,HBV DNA,ALT,aspartate aminotransferase(AST),albumin(Alb),and LSM between the two groups.There were statistically significant differences in HBsAg,anti-HBc,and ALT levels before and after follow-up in the low HBsAg group,but no statistically significant differences in anti-HBe,HBV DNA,AST,Alb,and LSM levels.There were statistically significant differences in HBsAg and anti-HBc before and after follow-up in the high HBsAg group,but no statistically significant differences in anti-HBe,HBV DNA,ALT,AST,Alb,and LSM.A liver biopsy was performed in 66 patients during followup,and 27.27%of the patients had moderate liver damage.In the low HBsAg group,45.76%of patients had a HBsAg decrease rate of≥0.5 logioIU/ml,10.17%of patients had HBV DNA negative conversion,88.14%of patients had a persistently normal ALT,and 96.61%of patients had a persistently normal LSM at the end of follow-up.In the high HBsAg group,3.75%of patients had a HBsAg decrease of≥0.5 logio IU/ml,no patient had a HBV DNA negative conversion,90%of patients had a persistently normal ALT,and 98.75%of patients had a persistently normal LSM.There were statistically significant differences in the HBsAg decreaserate(45.76%vs.3.75%,X^(2)=32.975,P<0.001)and HBV DNA negative conversion rate(10.17%vs.0,X^(2)=6.219,P=0.013)between the two groups at the end of follow-up,but there were no statistically significant differences in the persistently normal ALT and LSM rates.Conclusion The vast majority of patients with HBeAg-negative chronicHI BV infectioninthe indeterminate phase with low viral load have persistent hypoviremia over the long term.Some patients have liver tissue damage and may progress to cirrhosis and liver cancer as a result of HBV DNA positivity,so antiviral treatment should be initiated in all.展开更多
Substantial progress has been made over recent years in visible light-driven dual photoredox/copper catalyzed atom transfer radical polymerization (photo-ATRP) through the design of photocatalysts (PCs) and the optimi...Substantial progress has been made over recent years in visible light-driven dual photoredox/copper catalyzed atom transfer radical polymerization (photo-ATRP) through the design of photocatalysts (PCs) and the optimization of reaction conditions. However, it remains challenging to achieve efficient photo-ATRP with low loadings of both photocatalyst and copper(II). In this study, two donor-acceptor organic PCs based on pyrazino[2,3-f][1,10]phenanthroline were successfully used to achieve efficient Cu(II)-mediated photo-ATRP. These organic PCs exhibit excellent visible light absorption capabilities and thermally activated delayed fluorescence (TADF) properties. Under blue light irradiation, the PCs facilitated highly efficient and oxygen-tolerant polymerization with an extremely low catalyst loading (50 ppb). This system demonstrated a broad applicability to various monomers, achieving successful polymerization of methacrylates, acrylates, and styrene. Additionally, efficient photo-ATRP on a large scale (250 mL) was achieved, resulting in narrow molecular weight polymers with high monomer conversions and high chain-end fidelity. This work provides an in-depth investigation into the regulatory process of photo-ATRP, offering new insights into the intricate mechanism of oxygen tolerance.展开更多
Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomi...Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability.In this study,we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO_(2)reduction.N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers.The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride(Pt Cu-cr CN)exhibited high selectivity and activity for CO_(2)conversion without the addition of any cocatalyst or sacrificial agent.In particular,we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH_(4)generation.The mechanism of CO_(2)photoreduction for Pt Cu-cr CN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images,in situ irradiated X-ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fourier transform spectroscopy.The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.展开更多
The effects of fire exposure,reinforcement ratio and the presence of axial load under fire on the seismic behavior of reinforced concrete(RC) shear walls were investigated.Five RC shear walls were tested under low cyc...The effects of fire exposure,reinforcement ratio and the presence of axial load under fire on the seismic behavior of reinforced concrete(RC) shear walls were investigated.Five RC shear walls were tested under low cyclic loading.Prior to the cyclic test,three specimens were exposed to fire and two of them were also subjected to a constant axial load.Test results indicate that the ultimate load of the specimen with lower reinforcement ratio is reduced by 15.8%after exposure to elevated temperatures.While the reductions in the energy dissipation and initial stiffness are 59.2%and 51.8%,respectively,which are much higher than those in the ultimate load.However,this deterioration can be slowed down by properly increasing reinforcement due to the strength and stiffness recovery of steel bars after cooling.In addition,the combined action of elevated temperatures and axial load results in more energy dissipation than the action of fire exposure alone.展开更多
To investigate the seismic behavior of specially shaped column joints with X-shaped reinforcement,two groups of specimens with or without X-shaped reinforcement in joint core region were tested under constant axial co...To investigate the seismic behavior of specially shaped column joints with X-shaped reinforcement,two groups of specimens with or without X-shaped reinforcement in joint core region were tested under constant axial compression load and low reversed cyclic loading,which imitated low to moderate earthquake force.The seismic behavior of specially shaped column joints with X-shaped reinforcement in terms of bearing capacity,displacement,ductility,hysteretic curve,stiffness degradation and energy dissipation was studied and compared to that without Xshaped reinforcement in joint core region.With the damage estimation model,the accumulated damage was analyzed.The shearing capacity formula of specially shaped column joints reinforced by X-shaped reinforcement was proposed with a simple form.The test results show that X-shaped reinforcement is an effective measure for improving the seismic behavior of specially shaped column joints including deformation behavior,ductility and hysteretic characteristic.All specimens were damaged with gradual stiffness degeneration.In addition,X-shaped reinforcement in the joint core region is an effective way to lighten the degree of cumulated damage.The good seismic performance obtained from the specially shaped column joint with X-shaped reinforcement can be used in engineering applications.The test value is higher than the calculated value,which indicates that the formula is safe for the design of specially shaped column joints.展开更多
An effective oxygen evolution electrode with Ir0.6Sn0.4O2 was designed for proton exchange membrane(PEM)water electrolyzers.The anode catalyst layer exhibits a jagged structure with smaller particles and pores,which p...An effective oxygen evolution electrode with Ir0.6Sn0.4O2 was designed for proton exchange membrane(PEM)water electrolyzers.The anode catalyst layer exhibits a jagged structure with smaller particles and pores,which provide more active sites and mass transportation channels.The prepared IrSn electrode showed a cell voltage of 1.96 V at 2.0 A cm^-2 with Ir loading as low as 0.294 mg cm^-2.Furthermore,Ir Sn electrode with different anode catalyst loadings was investigated.The IrS n electrode indicates higher mass current and more stable cell voltage than the commercial Ir Black electrode at low loading.展开更多
The low-cycle loading test of two staggered slab-column-boundary beam joints was carried out to study their seismic performance.The crack development,load-displacement relationship,displacement ductility,and energy di...The low-cycle loading test of two staggered slab-column-boundary beam joints was carried out to study their seismic performance.The crack development,load-displacement relationship,displacement ductility,and energy dissipation performance of the staggered slab-column joints(SSCJ)were studied.Experimental results reveal that both specimens present short-column brittle shear failure.Furthermore,an obvious hysteretic curve pinching phenomenon occurred.Thus,it can be concluded that the seismic performance of the joints is insufficient.These results suggest that the anchorage of the longitudinal reinforcement of the slab in the joint’s core area should be improved,and attention should be paid to the short-column stirrup configuration of the SSCJ.These results can provide a research basis for the design of such joints in future applications.展开更多
In this paper a novel method to generate high-precision and continuously adjustable digital time-delay by utilizing the linear phase of a FIR filter is presented. The generated time-delay can be continuously changed b...In this paper a novel method to generate high-precision and continuously adjustable digital time-delay by utilizing the linear phase of a FIR filter is presented. The generated time-delay can be continuously changed by adjusting the filter weights. The time-delay is pre cise and valid for wide-band, while the computational load is low. The proposed approach can find applications in wide-band digital beamforming, adaptive delay estimation, temporal analy sis of reflected waveform, etc.. In the paper, the basic principle, design steps and simulation re sults are given. Also shown are some typical practical applications.展开更多
Improving the performance of proton exchange membrane fuel cells(PEMFCs)requires deep understanding of the reac-tive transport processes inside the catalyst layers(CLs).In this study,a particle-overlapping model is de...Improving the performance of proton exchange membrane fuel cells(PEMFCs)requires deep understanding of the reac-tive transport processes inside the catalyst layers(CLs).In this study,a particle-overlapping model is developed for accu-rately describing the hierarchical structures and oxygen reactive transport processes in CLs.The analytical solutions derived from this model indicate that carbon particle overlap increases ionomer thickness,reduces specific surface areas of ionomer and carbon,and further intensifies the local oxygen transport resistance(R_(other)).The relationship between Rother and roughness factor predicted by the model in the range of 800-1600 sm^(-1) agrees well with the experiments.Then,a multiscale model is developed by coupling the particle-overlapping model with cell-scale models,which is validated by comparing with the polarization curves and local current density distribution obtained in experiments.The relative error of local current density distribution is below 15%in the ohmic polarization region.Finally,the multiscale model is employed to explore effects of CL structural parameters including Pt loading,I/C,ionomer coverage and carbon particle radius on the cell performance as well as the phase-change-induced(PCI)flow and capillary-driven(CD)flow in CL.The result demonstrates that the CL structural parameters have significant effects on the cell performance as well as the PCI and CD flows.Optimizing the CL structure can increase the current density and further enhance the heat-pipe effect within the CL,leading to overall higher PCI and CD rates.The maximum increase of PCI and CD rates can exceed 145%.Besides,the enhanced heat-pipe effect causes the reverse flow regions of PCI and CD near the CL/PEM interface,which can occupy about 30%of the CL.The multiscale model significantly contributes to a deep understanding of reactive trans-port and multiphase heat transfer processes inside PEMFCs.展开更多
基金the financial supports from the National Natural Science Foundation of China(21975281,21773293,21603264)CAS Pioneer Hundred Talents Program+2 种基金the National Key Research and Development Program of China(2016YFA0203301)Jiangsu Planned Projects for Postdoctoral Research Funds(2019K048)Suzhou Science and Technology Plan Project(SYG201926)。
文摘Transitional metal alloy and compounds have been developed as the low cost and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,a high mass loading of these catalysts is commonly needed to achieve acceptable catalytic performance,which could cause such problems as battery weight gain,mass transport blocking,and catalyst loss.We report herein the preparation of fine CoNi nanoparticles(5-6 nm)anchored inside a nitrogendoped defective carbon nanotube network(CoNi@N-DCNT)by a transient Joule heating method.When utilized as an electrocatalyst for oxygen reduction and evolution in alkaline media,the CoNi@N-DCNT film catalyst with a very low mass loading of 0.06 mg cm^(-2) showed excellent bifunctional catalytic performance.For ORR,the onset potential(Eonset)and the half-wave potential(E_(1/2))were 0.92 V versus reversible hydrogen electrode(vs.RHE)and 0.83 V(vs.RHE),respectively.For OER,the potential at the current density(J)of 10 mA cm^(-2)(E_(10))was 1.53 V,resulting in an overpotential of 300 mV much lower than that of the commercial RuO_(2) catalyst(320 mV).The potential gap between E_(1/2) and E_(10) was as small as 0.7 V.Considering the low mass loading,the mass activity at E_(10) reached at 123.2 A g^(-1),much larger than that of the RuO_(2) catalyst and literature results of transitional metal-based bifunctional catalysts.Moreover,the CoNi@N-DCNT film catalyst showed very good long-term stability during the ORR and OER test.The excellent bifunctional catalytic performance could be attributed to the synergistic effect of the bimetal alloy.
基金financial support from the National Natural Science Foundation of China (No. 21472033)the National Key R&D Program of China (No. 2018YFB1501604)the Fundamental Research Funds for the Central Universities (No. PA2020GDKC0021)。
文摘The hydroarylation reaction of terminal alkynes with arylboronic acids catalyzed by low(400 ppm) loadings of palladium has been developed. The reaction is broad in scope and high-yielding, even on multigram scale. It is suitable for the synthesis of alkenes labeled with deuterium, and for the late-stage modification of bioactive molecules.
文摘The very long tradition of the activated sludge treatment model within the water industry has demonstrated very versatile possibilities to adopt the operation mode for different enhancements. By looking into other treatment models within the activated sludge family it is possible to find alternatives for the operation. This paper concentrates on the possibilities to improve even small WWTP with respect to energy savings. The small plant in Northern Sweden, called Rosvik WWTP, is given as an example. Some important findings related to the intermittent aeration mode may be summarized as follows: 1) An energy savings for the operation of the small WWTP with respect to aeration needs that resulted in a decrease of the energy power supply by more than 35%, as compared with the previous operation based on continuous aeration;2) The up to date effluent levels with respect to the main pollutants have remained at very good levels in 2020, P-level averages 0.16 mg P/l versus consent level <</span><span> </span><span style="font-family:Verdana;">0.5 mg P/l;COD-level 40 versus <</span><span> </span><span><span style="font-family:Verdana;">70 mg/l and BOD</span><sub><span style="font-family:Verdana;">7</span></sub><span style="font-family:Verdana;"> 9 versus <</span></span><span> </span><span><span style="font-family:Verdana;">15 mg/l;3) Sometimes, also improved sludge settling characteristics have been observed, thus providing improved discharge figures;4) The potential to develop an enhanced biological phosphorus removal. There are however </span><span style="font-family:Verdana;">some needed conditions to accomplish these improvements: 1) Reliable</span><span style="font-family:Verdana;"> on-line probes for both oxygen control, SS-concentration control and optionally also for nitrogen control;2) A flexible automation system that allows the needed process modifications to take place;3) And finally, very important dedicated and competent plant operators, with the needed curiosity for operation improvements.
文摘The Sri Lankan national water authority, that is The National Water Supply and Drainage Board (NWS&DB) has taken a new wastewater treatment plant into operation at Ja Ela, North of Colombo. The plant has been in operation since September 2011. In April 2012, it was concluded how a test of the aeration efficiency and a performance test should be carried out. The tests have been based on the actual loading of the plant and the analysis results from the daily process control. The evaluation of the aeration efficiency is not reported in this paper. The paper presents the overall performance of the water treatment part of the plant during start-up conditions, from fall 2011 through the first five months of 2012. The results from the operation are found in Table 1. An important circumstance at the plant is the current very low loading in comparison with the design load. This fact has resulted in an introduction of an intermittent mode of the aeration (nitrification) reactor. Based on operation figures, during more than a month (May 2012), it has been possible to give a realistic assessment of the overall performance. The most striking results are summarized as follows: 1) The intermittent operation has enabled an energy efficient operation of the plant. By the introduction of the intermittent aeration, the energy consumption has been reduced by around 75%, compared with the continuous operation mode;2) The plant performance during the intermittent operation has been improved with respect to virtually all important pollution variables. The most striking improvement is the discharge total P level, reflecting that a substantial enhanced biological phosphorus removal takes. The typical discharge levels found during May 2012, were compared with the earlier obtained values. It is important to underline that the loading on the plant has slightly increased during May as compared with the previous operation period.
基金the New Century Excellent Talents in University Under Grant No.290Heilongjiang Key Program on Science and Technology Under Grant No. GC04A609arbin Key Program on Science and Technology Under Grant No. 2004AA9CS187.
文摘Tests of nine angle-steel concrete column （ASCC） specimens under low cyclic loading are described in a companion paper （Zheng and Ji, 2008）. In this paper, the skeleton curves from the numerical simulation are presented, and show good agreement with the test results. Furthermore, parametric studies are conducted to explore the influence of factors such as the axial compression ratio, shear steel plate ratio, steel ratio, prismatic concrete compression strength, yield strength of angle steel and shear span ratio, etc., on the monotonic load-displacement curves of the ASCCs. Based on a statistical analysis of the calculated results, hysteretic models for load-displacement and moment-curvature are proposed, which agree well with the test results. Finally, some suggestions concerning the conformation of ASCCs are proposed, which could be useful in engineering practice.
文摘The ballistic properties of a low solid loading composite solid propellant family （Butalites） was studied experimentally by using propellant formulations based on hydroxy-terminated polybutadiene pre-polymer （HTPB） as fuel binder main backbone, mono and bi-modal system ammonium perchlorate oxidizer （AP）, copper chromite （CC） as burning rate accelerator and aluminum powder （A1） as metallic fuel. Higher pressures and AP contents as well as smaller AP particle size were found to increase burning rate. The same behavior verified with AI and CC addition. A significant increase of burning rate was recorded when CC added to the aluminized formulations compared with the non-aluminized of the same oxidizer solid loading and particle size.
基金supported by National Natural Science Foundation of China (Grant No. 50875173)Shanghai Municipal Education Commission Key Foundation of China (Grant No. 09ZZ157)Shanghai Leading Academic Discipline Project of China (Grant No. J50503)
文摘There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to use high performance lightweight materials.The former method takes very few considerations on the structural strengthening effects caused by the massive small loads in service.In order to ensure safety,the design is usually conservative,but the strength potential of the component is not fully exerted.In the latter method,cost is the biggest obstacle to lightweight materials in automotive applications.For the purpose of light weighting design on a fuel cell vehicle,the new design method is applied on drive shafts.The method is based on the low amplitude load strengthening characteristics of the material,and allows the stress,corresponding to test load,to enter into the strengthened range of the material.Under this condition,the light weighting design should assure that the reliability of the shaft is not impaired,even maximizes the strength potential of machine part in order to achieve the weight reduction and eventually to reduce the cost.At last,the feasibility of the design is verified by means of strength analysis and modal analysis based on the CAD model of light weighted shaft.The design applies to the load case of half shaft in independent axle,also provides technological reference for the structural lightweight design of vehicles and other machineries.
基金National Natural Science Foundation of China (10802003)
文摘Tests with middle-crack tension （M（T）） specimens made of Al 2324-T39 and Al 7050-T7451 are conducted to investigate the influence of low load truncation level on fatigue crack growth. The six different truncated spectra are obtained by removing the small cycles of which amplitudes are less than the specified percentages of the maximum amplitude in the basic flight-by-flight loading spectrum and the remainder of the spectrum is untouched. The tests indicate that the mean level of fatigue crack growth life （FCGL） increases as the load truncation level is enhanced. Considering both the time saving and the influence on FCGL, there is an applicable choice （i.e. spectrum S2 or spectrum S3 in this investigation） for full scale fatigue test. The scatter of FCGL becomes much larger than that under the basic spectrum when the load truncation level is increased to a specified high level, mainly due to the occurrence of crack slanting and branching under the high level truncated loading spectra.
基金Supported by Clinical Research Funds from Department of Gastroenterology and Hepatology,Kashiwa Hospital,Jikei University School of Medicine
文摘AIM:To assess the efficacy and advantages of 4-wk pegylated interferon a-2a(peg-IFN-a2a) monotherapy for chronic hepatitis C patients with strong predictors of sustained virologic response(SVR).METHODS:Patients(n = 33) with genotype 2 and low viral load(< 100 KIU/mL),who became HCV RNA negative after 1 wk of IFN treatment,were randomly allocated to receive a 4-or 12-wk treatment course at a ratio of 2:1,respectively,with a subsequent 24-wk follow-up period.Peg-IFN-a2a was administered subcutaneously at a dose of 180 μg or 90 μg once weekly.SVR was defined as absence of serum HCV RNA at the end of the follow-up period.RESULTS:All patients completed the treatment schedule,and more than half were symptom-free during the treatment.In the 4-wk treatment group,20 of 22(91%) patients achieved SVR.Two patients relapsed,but achieved SVR following re-treatment with peg-IFN-a2a alone.In the 12-wk treatment group,11 of 11(100%) patients attained SVR.CONCLUSION:Our results show that a 4-wk course of peg-IFN-a2a monotherapy can achieve a high SVR rate in "IFN-sensitive" patients,without negatively affecting outcome.
基金supported by the National Natural Science Foundation of China(2210829)We thank Analysis&Testing Laboratory for Life Sciences and Medicine of Air Force Medical University for HR MS analysis.
文摘A palladium catalytic system incorporating novel Fc-JosiPhos ligands enables efficient C–N bond formation with diverse(hetero)aryl halides under low palladium loading(0.1 mol%).We rationally designed novel ferrocenyl phosphine-derived JosiPhos ligands(L1–L3).These ligands incorporate a ferrocenyl group providing greater steric bulk than tert-butyl or cyclohexyl and superior electron donation to cyclohexyl,along with a tunable side chain.They delivered excellent yields in the catalytic coupling of challenging(hetero)aryl chlorides with hydrazine.The scalable synthesis of arylhydrazines(5mmol scale)and subsequent cyclization to pyrazoles(65%–91%yields)highlights their potential for industrial conversion.Furthermore,the modularity of this strategy supports late-stage pharmaceutical functionalization,exemplified by TRPC inhibitor intermediate.
基金supported by Beijing Natural Science Foundation(No.2232062)National Natural Science Foundation of China(No.21875223)。
文摘Highly efficient catalysts for electrolysis of water are crucial to the development of hydrogen energy which is helpful to carbon neutralization.Recently,high temperature shock(HTS),with advantage of rapid speed,universality and scalable production,has been a promising method in synthesis of nanomaterials.In this paper,HST was used to treat low Pt loading Mo_(6)S_(8)for enhanced water splitting performance.Impressively,the optimized MoS_(2)/MoO_(2)/Mo_(6)S_(8)nano-composite with low Pt mass loading(~4%)displays well hydrogen evolution reaction(HER)electrochemical performance.The overpotential is 124 mV to reach 10 mA/cm^(2)and the corresponding Tafel slope is 88 mV/dec in acidic electrolyte.Its mass activity is 6.2 mA/μg_(Pt)at-124 mV vs.RHE,which is almost 2 times relative to 20%Pt/C.Moreover,it presents distinguished stability even after 2000 cycles.This work will broaden the way of catalysts preparation and the application of hydrogen evolution.
文摘Objective To analyze the clinical characteristics of HBeAg-negative chronic hepatitis B virus(HBV)infection in indeterminate phase with a low viral load.Methods Onehundredd and thirty-nine cases with persistent normal alanine aminotransferase(ALT)and HBeAg-negative chronic HBV infection with low viral load who visited the Department of Infectious Diseases of the Affiliated Hospital of Yan'an University from September 2013to July 2021 wereretrospectively collected.Patients were divided into low hepatitis B surface antigen(HBsAg)group(n=59)and high HBsAg group(n=80)according to the baseline hepatitis B surface antigen(HBsAg)level.The changes of various indicators at baseline and follow-up endpoints were analyzed between the two groups.The rate of HBsAg decrease≥0.5 logio IU/ml,HBV DNA negative conversion rate,ALT persistently normal rate,and liver stiffness measurement(LSM)persistently normal rate at the end of the follow-up were compared.The t-test,or non-parametric Mann-Whitney U test,and Wilcoxon signed rank test were used for comparison of continuous data between the two groups.The x^(2)test,or Fisher's exact probability method,was used for comparing count data between the two groups.ResultsThere were statistically significant differences in age,gender,and HBsAg at baseline,but therewasnostatistically significant difference in terms of family history of hepatitis B,follow-up time,anti-HBe,anti-HBc,HBV DNA,ALT,aspartate aminotransferase(AST),albumin(Alb),and LSM between the two groups.There were statistically significant differences in HBsAg,anti-HBc,and ALT levels before and after follow-up in the low HBsAg group,but no statistically significant differences in anti-HBe,HBV DNA,AST,Alb,and LSM levels.There were statistically significant differences in HBsAg and anti-HBc before and after follow-up in the high HBsAg group,but no statistically significant differences in anti-HBe,HBV DNA,ALT,AST,Alb,and LSM.A liver biopsy was performed in 66 patients during followup,and 27.27%of the patients had moderate liver damage.In the low HBsAg group,45.76%of patients had a HBsAg decrease rate of≥0.5 logioIU/ml,10.17%of patients had HBV DNA negative conversion,88.14%of patients had a persistently normal ALT,and 96.61%of patients had a persistently normal LSM at the end of follow-up.In the high HBsAg group,3.75%of patients had a HBsAg decrease of≥0.5 logio IU/ml,no patient had a HBV DNA negative conversion,90%of patients had a persistently normal ALT,and 98.75%of patients had a persistently normal LSM.There were statistically significant differences in the HBsAg decreaserate(45.76%vs.3.75%,X^(2)=32.975,P<0.001)and HBV DNA negative conversion rate(10.17%vs.0,X^(2)=6.219,P=0.013)between the two groups at the end of follow-up,but there were no statistically significant differences in the persistently normal ALT and LSM rates.Conclusion The vast majority of patients with HBeAg-negative chronicHI BV infectioninthe indeterminate phase with low viral load have persistent hypoviremia over the long term.Some patients have liver tissue damage and may progress to cirrhosis and liver cancer as a result of HBV DNA positivity,so antiviral treatment should be initiated in all.
基金financial support of the National Natural Science Foundation of China(No.22271044).
文摘Substantial progress has been made over recent years in visible light-driven dual photoredox/copper catalyzed atom transfer radical polymerization (photo-ATRP) through the design of photocatalysts (PCs) and the optimization of reaction conditions. However, it remains challenging to achieve efficient photo-ATRP with low loadings of both photocatalyst and copper(II). In this study, two donor-acceptor organic PCs based on pyrazino[2,3-f][1,10]phenanthroline were successfully used to achieve efficient Cu(II)-mediated photo-ATRP. These organic PCs exhibit excellent visible light absorption capabilities and thermally activated delayed fluorescence (TADF) properties. Under blue light irradiation, the PCs facilitated highly efficient and oxygen-tolerant polymerization with an extremely low catalyst loading (50 ppb). This system demonstrated a broad applicability to various monomers, achieving successful polymerization of methacrylates, acrylates, and styrene. Additionally, efficient photo-ATRP on a large scale (250 mL) was achieved, resulting in narrow molecular weight polymers with high monomer conversions and high chain-end fidelity. This work provides an in-depth investigation into the regulatory process of photo-ATRP, offering new insights into the intricate mechanism of oxygen tolerance.
文摘Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability.In this study,we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO_(2)reduction.N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers.The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride(Pt Cu-cr CN)exhibited high selectivity and activity for CO_(2)conversion without the addition of any cocatalyst or sacrificial agent.In particular,we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH_(4)generation.The mechanism of CO_(2)photoreduction for Pt Cu-cr CN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images,in situ irradiated X-ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fourier transform spectroscopy.The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.
基金Project(200801410005) supported by Doctoral Foundation of Ministry of Education of China
文摘The effects of fire exposure,reinforcement ratio and the presence of axial load under fire on the seismic behavior of reinforced concrete(RC) shear walls were investigated.Five RC shear walls were tested under low cyclic loading.Prior to the cyclic test,three specimens were exposed to fire and two of them were also subjected to a constant axial load.Test results indicate that the ultimate load of the specimen with lower reinforcement ratio is reduced by 15.8%after exposure to elevated temperatures.While the reductions in the energy dissipation and initial stiffness are 59.2%and 51.8%,respectively,which are much higher than those in the ultimate load.However,this deterioration can be slowed down by properly increasing reinforcement due to the strength and stiffness recovery of steel bars after cooling.In addition,the combined action of elevated temperatures and axial load results in more energy dissipation than the action of fire exposure alone.
基金Supported by National Natural Science Foundation of China (No. 50878141)Hebei Natural Science Foundation,China (No. E2011202013)High School of Hebei Science and Technology Research Youth Foundation,China(No. Q2012083)
文摘To investigate the seismic behavior of specially shaped column joints with X-shaped reinforcement,two groups of specimens with or without X-shaped reinforcement in joint core region were tested under constant axial compression load and low reversed cyclic loading,which imitated low to moderate earthquake force.The seismic behavior of specially shaped column joints with X-shaped reinforcement in terms of bearing capacity,displacement,ductility,hysteretic curve,stiffness degradation and energy dissipation was studied and compared to that without Xshaped reinforcement in joint core region.With the damage estimation model,the accumulated damage was analyzed.The shearing capacity formula of specially shaped column joints reinforced by X-shaped reinforcement was proposed with a simple form.The test results show that X-shaped reinforcement is an effective measure for improving the seismic behavior of specially shaped column joints including deformation behavior,ductility and hysteretic characteristic.All specimens were damaged with gradual stiffness degeneration.In addition,X-shaped reinforcement in the joint core region is an effective way to lighten the degree of cumulated damage.The good seismic performance obtained from the specially shaped column joint with X-shaped reinforcement can be used in engineering applications.The test value is higher than the calculated value,which indicates that the formula is safe for the design of specially shaped column joints.
基金financially supported by the National Natural Science Foundation of China(U1664259)State Grid Corporation of China(No.SGTYHT/15-JS-191,PEMWE MEA Preparation and degradation mechanism)
文摘An effective oxygen evolution electrode with Ir0.6Sn0.4O2 was designed for proton exchange membrane(PEM)water electrolyzers.The anode catalyst layer exhibits a jagged structure with smaller particles and pores,which provide more active sites and mass transportation channels.The prepared IrSn electrode showed a cell voltage of 1.96 V at 2.0 A cm^-2 with Ir loading as low as 0.294 mg cm^-2.Furthermore,Ir Sn electrode with different anode catalyst loadings was investigated.The IrS n electrode indicates higher mass current and more stable cell voltage than the commercial Ir Black electrode at low loading.
基金The National Natural Science Foundation of China(No.59878013).
文摘The low-cycle loading test of two staggered slab-column-boundary beam joints was carried out to study their seismic performance.The crack development,load-displacement relationship,displacement ductility,and energy dissipation performance of the staggered slab-column joints(SSCJ)were studied.Experimental results reveal that both specimens present short-column brittle shear failure.Furthermore,an obvious hysteretic curve pinching phenomenon occurred.Thus,it can be concluded that the seismic performance of the joints is insufficient.These results suggest that the anchorage of the longitudinal reinforcement of the slab in the joint’s core area should be improved,and attention should be paid to the short-column stirrup configuration of the SSCJ.These results can provide a research basis for the design of such joints in future applications.
文摘In this paper a novel method to generate high-precision and continuously adjustable digital time-delay by utilizing the linear phase of a FIR filter is presented. The generated time-delay can be continuously changed by adjusting the filter weights. The time-delay is pre cise and valid for wide-band, while the computational load is low. The proposed approach can find applications in wide-band digital beamforming, adaptive delay estimation, temporal analy sis of reflected waveform, etc.. In the paper, the basic principle, design steps and simulation re sults are given. Also shown are some typical practical applications.
基金supported by the National Key Research and Development Program(2021YFB4001701)National Nature Science Foundation of China(52376074)the Fundamental Research Funds for the Central Universities.
文摘Improving the performance of proton exchange membrane fuel cells(PEMFCs)requires deep understanding of the reac-tive transport processes inside the catalyst layers(CLs).In this study,a particle-overlapping model is developed for accu-rately describing the hierarchical structures and oxygen reactive transport processes in CLs.The analytical solutions derived from this model indicate that carbon particle overlap increases ionomer thickness,reduces specific surface areas of ionomer and carbon,and further intensifies the local oxygen transport resistance(R_(other)).The relationship between Rother and roughness factor predicted by the model in the range of 800-1600 sm^(-1) agrees well with the experiments.Then,a multiscale model is developed by coupling the particle-overlapping model with cell-scale models,which is validated by comparing with the polarization curves and local current density distribution obtained in experiments.The relative error of local current density distribution is below 15%in the ohmic polarization region.Finally,the multiscale model is employed to explore effects of CL structural parameters including Pt loading,I/C,ionomer coverage and carbon particle radius on the cell performance as well as the phase-change-induced(PCI)flow and capillary-driven(CD)flow in CL.The result demonstrates that the CL structural parameters have significant effects on the cell performance as well as the PCI and CD flows.Optimizing the CL structure can increase the current density and further enhance the heat-pipe effect within the CL,leading to overall higher PCI and CD rates.The maximum increase of PCI and CD rates can exceed 145%.Besides,the enhanced heat-pipe effect causes the reverse flow regions of PCI and CD near the CL/PEM interface,which can occupy about 30%of the CL.The multiscale model significantly contributes to a deep understanding of reactive trans-port and multiphase heat transfer processes inside PEMFCs.
