The loading strategy of cocatalysts affects its activity exerting and atom utilization.Here,a novel strategy for loading precious metal(Pt)cocatalysts by means of ultrathin N-doped carbon layer is reported.The strateg...The loading strategy of cocatalysts affects its activity exerting and atom utilization.Here,a novel strategy for loading precious metal(Pt)cocatalysts by means of ultrathin N-doped carbon layer is reported.The strategy is based on a pyrolysis process of predesigned N-containing polymers and Pt complexes on hard-template surface,during which Pt can be reduced by carbon from pyrolysis at high temperatures.Finally,the hollow TiO_(2)composite with stable and dispersed Pt on its inner surface was prepared.It shows an ultrahigh photocatalytic H_(2)production activity as high as 25.7 mmol h^(-1)g^(-1)with methanol as sacrificial regent,and displays an apparent quantum yield as 13.2%.The improved photocatalytic activity and stability can be attributed to the highly dispersed and ultrafine Pt nanoparticles,enhanced interaction between Pt-species and carbon support,fast photo-excited electron transport from the high graphitization degree of NC layers,ample oxygen vacancies/defects,as well as the manipulated local charge distribution of Pt/NC-layer configuration.Additionally,the universality of the proposed strategy was demonstrated by replacing metal sources(such as,Ru and Pd).This work presented a promising strategy for the design and development of novel photocatalysts,which shows a broad application prospect.展开更多
Reducing a Pt loading with improved power output and durability is essential to promote the large-scale application of proton exchange membrane fuel cells(PEMFCs).To achieve this goal,constructing optimized structure ...Reducing a Pt loading with improved power output and durability is essential to promote the large-scale application of proton exchange membrane fuel cells(PEMFCs).To achieve this goal,constructing optimized structure of catalyst layers with efficient mass transportation channels plays a vital role.Herein,PEMFCs with order-structured cathodic electrodes were fabricated by depositing Pt nanoparticles by Ebeam onto vertically aligned carbon nanotubes(VACNTs)growth on Al foil via plasma-enhanced chemical vapor deposition.Results demonstrate that the proportion of hydrophilic Pt-deposited region along VACNTs and residual hydrophobic region of VANCTs without Pt strongly influences the cell performance,in particular at high current densities.When Pt nanoparticles deposit on the top depth of around 600 nm on VACNTs with a length of 4.6μm,the cell shows the highest performance,compared with others with various lengths of VACNTs.It delivers a maximum power output of 1.61 W cm^(-2)(H_(2)/O_(2),150 k Pa)and 0.79 W cm^(-2)(H_(2)/Air,150 k Pa)at Pt loading of 50μg cm^(-2),exceeding most of previously reported PEMFCs with Pt loading of<100μg cm^(-2).Even though the Pt loading is down to 30μg cm^(-2)(1.36 W cm^(-2)),the performance is also better than 100μg cm^(-2)(1.24 W cm^(-2))of commercial Pt/C,and presents better stability.This excellent performance is critical attributed to the ordered hydrophobic region providing sufficient mass passages to facilitate the fast water drainage at high current densities.This work gives a new understanding for oxygen reduction reaction occurred in VACNTs-based ordered electrodes,demonstrating the most possibility to achieve a substantial reduction in Pt loading<100μg cm^(-2) without sacrificing in performance.展开更多
The National Health Service(NHS)is a term used to describe the publicly funded healthcare delivery system providing quality healthcare services in the United Kingdom.There are several challenges militating against the...The National Health Service(NHS)is a term used to describe the publicly funded healthcare delivery system providing quality healthcare services in the United Kingdom.There are several challenges militating against the effective laboratory service delivery in the NHS in England.Biomedical scientists work in healthcare to diagnose disease and evaluate the effectiveness of treatment through the analysis of body fluids and tissue samples from patients.They provide the"engine room"of modern medicine with 70%of diagnosis based on the laboratory results generated by them.This review involved the search of literature for information on working condition of biomedical scientist in the NHS in England.Laboratory service delivery in the NHS in England faces numerous daunting challenges;staffing levels in the last few years have become dangerously low,less remunerated,relatively less experienced and predominantly band 5's,multidisciplinary rather than specialty based,associated with working more unsocial hours without adequate recovery time,de-banding of staff,high staff turnaround,profit and cost driven rather than quality.These factors has resulted in burn out,low morale,high sickness absences,increased error rate,poor team spirit,diminished productivity and suboptimal laboratory service delivery.There is the urgent need to retract our steps on unpopular policies to ensure that patient care is not compromised by ensuring adequate staffing level and mix,ensuring adequate remuneralion of laboratory staff,implementing evidenced-based specialty oriented service,determining the root cause/s for the high staff turnover and implementing corrective action,identifying other potential sources of waste in the system rather than pruning the already dangerously low staffing levels and promoting a quality delivery side by side cost effectiveness.展开更多
Microwave-absorbing polymeric composites based on single-walled carbon nanotubes （SWNTs） are fabricated via a simple yet versatile method, and these SWNT-epoxy composites exhibit very impressive microwave absorption...Microwave-absorbing polymeric composites based on single-walled carbon nanotubes （SWNTs） are fabricated via a simple yet versatile method, and these SWNT-epoxy composites exhibit very impressive microwave absorption perfor- mances in a range of 2 GHz-18 GHz. For instance, a maximum absorbing value as high as 28 dB can be achieved for each of these SWNT-epoxy composites （1.3-mm thickness） with only 1 wt% loading of SWNTs, and about 4.8 GHz bandwidth, corresponding to a microwave absorption performance higher than 10 dB, is obtained. Furthermore, such low and appro- priate loadings of SWNTs also enhance the mechanical strength of the composite. It is suggested that these remarkable results are mainly attributable to the excellent intrinsic properties of SWNTs and their homogeneous dispersion state in the polymer matrix.展开更多
This standard specifies the definitions, theory, apparatus, specimens, procedures, test results and disposal, test error and report of test method for refractoriness under load of refractory products （non-differentia...This standard specifies the definitions, theory, apparatus, specimens, procedures, test results and disposal, test error and report of test method for refractoriness under load of refractory products （non-differential, with rising temperature）.展开更多
为提高基于行驶工况预测油耗的准确性,创新性地提出针对重型商用车细分市场构建行驶工况的研究思路。为验证此研究思路的必要性与合理性,以日用工业品市场为例,对国六商用车行驶工况进行大数据分析。依托车载天行健智能网联系统采集了...为提高基于行驶工况预测油耗的准确性,创新性地提出针对重型商用车细分市场构建行驶工况的研究思路。为验证此研究思路的必要性与合理性,以日用工业品市场为例,对国六商用车行驶工况进行大数据分析。依托车载天行健智能网联系统采集了该市场中3000辆国六系列半挂牵引车的用户行驶数据,通过数据清洗、运动学片段切分、数据降维、工况合成等一系列步骤,构建了3条代表性工况。以此为基础,采用AVL Cruise软件构建仿真模型,基于所构建工况预测目标市场的用户油耗,并与基于中国重型商用车瞬态工况(China world transient vehicle cycle,C-WTVC)和中国重型半牵引车行驶工况(China heavy-duty commercial vehicle test cycle for tractor-trailer,CHTC-TT)的预测结果进行对比。结果表明,与同车型国家标准工况(C-WTVC和CHTC-TT)相比,构建的日用工业品细分市场工况与目标市场下大数据统计的实际运行特征更接近,特征参数平均相对误差分别减少32.97个百分点和18.67个百分点,且能够更精确地预测用户使用油耗,预测精度分别提高7%和4%。针对重型商用车细分市场构建行驶工况能更精确地刻画目标市场用户的车辆使用特征,提高了用户油耗的预测精度。展开更多
基金supported by the Natural Science Foundation of the Shanxi Province of China(No.201801D121069)Graduate Education Innovation Foundation of Province Shanxi of China(No.2020SY359)。
文摘The loading strategy of cocatalysts affects its activity exerting and atom utilization.Here,a novel strategy for loading precious metal(Pt)cocatalysts by means of ultrathin N-doped carbon layer is reported.The strategy is based on a pyrolysis process of predesigned N-containing polymers and Pt complexes on hard-template surface,during which Pt can be reduced by carbon from pyrolysis at high temperatures.Finally,the hollow TiO_(2)composite with stable and dispersed Pt on its inner surface was prepared.It shows an ultrahigh photocatalytic H_(2)production activity as high as 25.7 mmol h^(-1)g^(-1)with methanol as sacrificial regent,and displays an apparent quantum yield as 13.2%.The improved photocatalytic activity and stability can be attributed to the highly dispersed and ultrafine Pt nanoparticles,enhanced interaction between Pt-species and carbon support,fast photo-excited electron transport from the high graphitization degree of NC layers,ample oxygen vacancies/defects,as well as the manipulated local charge distribution of Pt/NC-layer configuration.Additionally,the universality of the proposed strategy was demonstrated by replacing metal sources(such as,Ru and Pd).This work presented a promising strategy for the design and development of novel photocatalysts,which shows a broad application prospect.
基金finically supported by the National Natural Science Foundation of China(22075055)the Guangxi Science and Technology Project(AB16380030)the Innovation Project of Guangxi Graduate Education(YCSW2020052)。
文摘Reducing a Pt loading with improved power output and durability is essential to promote the large-scale application of proton exchange membrane fuel cells(PEMFCs).To achieve this goal,constructing optimized structure of catalyst layers with efficient mass transportation channels plays a vital role.Herein,PEMFCs with order-structured cathodic electrodes were fabricated by depositing Pt nanoparticles by Ebeam onto vertically aligned carbon nanotubes(VACNTs)growth on Al foil via plasma-enhanced chemical vapor deposition.Results demonstrate that the proportion of hydrophilic Pt-deposited region along VACNTs and residual hydrophobic region of VANCTs without Pt strongly influences the cell performance,in particular at high current densities.When Pt nanoparticles deposit on the top depth of around 600 nm on VACNTs with a length of 4.6μm,the cell shows the highest performance,compared with others with various lengths of VACNTs.It delivers a maximum power output of 1.61 W cm^(-2)(H_(2)/O_(2),150 k Pa)and 0.79 W cm^(-2)(H_(2)/Air,150 k Pa)at Pt loading of 50μg cm^(-2),exceeding most of previously reported PEMFCs with Pt loading of<100μg cm^(-2).Even though the Pt loading is down to 30μg cm^(-2)(1.36 W cm^(-2)),the performance is also better than 100μg cm^(-2)(1.24 W cm^(-2))of commercial Pt/C,and presents better stability.This excellent performance is critical attributed to the ordered hydrophobic region providing sufficient mass passages to facilitate the fast water drainage at high current densities.This work gives a new understanding for oxygen reduction reaction occurred in VACNTs-based ordered electrodes,demonstrating the most possibility to achieve a substantial reduction in Pt loading<100μg cm^(-2) without sacrificing in performance.
基金Supported by grant(NEI001)from the management of Nelson Biomedical Limited UK
文摘The National Health Service(NHS)is a term used to describe the publicly funded healthcare delivery system providing quality healthcare services in the United Kingdom.There are several challenges militating against the effective laboratory service delivery in the NHS in England.Biomedical scientists work in healthcare to diagnose disease and evaluate the effectiveness of treatment through the analysis of body fluids and tissue samples from patients.They provide the"engine room"of modern medicine with 70%of diagnosis based on the laboratory results generated by them.This review involved the search of literature for information on working condition of biomedical scientist in the NHS in England.Laboratory service delivery in the NHS in England faces numerous daunting challenges;staffing levels in the last few years have become dangerously low,less remunerated,relatively less experienced and predominantly band 5's,multidisciplinary rather than specialty based,associated with working more unsocial hours without adequate recovery time,de-banding of staff,high staff turnaround,profit and cost driven rather than quality.These factors has resulted in burn out,low morale,high sickness absences,increased error rate,poor team spirit,diminished productivity and suboptimal laboratory service delivery.There is the urgent need to retract our steps on unpopular policies to ensure that patient care is not compromised by ensuring adequate staffing level and mix,ensuring adequate remuneralion of laboratory staff,implementing evidenced-based specialty oriented service,determining the root cause/s for the high staff turnover and implementing corrective action,identifying other potential sources of waste in the system rather than pruning the already dangerously low staffing levels and promoting a quality delivery side by side cost effectiveness.
基金Project supported by the National Basic Research Program of China(Grant Nos.2012CB933401 and 2014CB643502)the National Natural Science Foundation of China(Grant Nos.21374050,51273093,and 51373078)
文摘Microwave-absorbing polymeric composites based on single-walled carbon nanotubes （SWNTs） are fabricated via a simple yet versatile method, and these SWNT-epoxy composites exhibit very impressive microwave absorption perfor- mances in a range of 2 GHz-18 GHz. For instance, a maximum absorbing value as high as 28 dB can be achieved for each of these SWNT-epoxy composites （1.3-mm thickness） with only 1 wt% loading of SWNTs, and about 4.8 GHz bandwidth, corresponding to a microwave absorption performance higher than 10 dB, is obtained. Furthermore, such low and appro- priate loadings of SWNTs also enhance the mechanical strength of the composite. It is suggested that these remarkable results are mainly attributable to the excellent intrinsic properties of SWNTs and their homogeneous dispersion state in the polymer matrix.
文摘This standard specifies the definitions, theory, apparatus, specimens, procedures, test results and disposal, test error and report of test method for refractoriness under load of refractory products （non-differential, with rising temperature）.
文摘为提高基于行驶工况预测油耗的准确性,创新性地提出针对重型商用车细分市场构建行驶工况的研究思路。为验证此研究思路的必要性与合理性,以日用工业品市场为例,对国六商用车行驶工况进行大数据分析。依托车载天行健智能网联系统采集了该市场中3000辆国六系列半挂牵引车的用户行驶数据,通过数据清洗、运动学片段切分、数据降维、工况合成等一系列步骤,构建了3条代表性工况。以此为基础,采用AVL Cruise软件构建仿真模型,基于所构建工况预测目标市场的用户油耗,并与基于中国重型商用车瞬态工况(China world transient vehicle cycle,C-WTVC)和中国重型半牵引车行驶工况(China heavy-duty commercial vehicle test cycle for tractor-trailer,CHTC-TT)的预测结果进行对比。结果表明,与同车型国家标准工况(C-WTVC和CHTC-TT)相比,构建的日用工业品细分市场工况与目标市场下大数据统计的实际运行特征更接近,特征参数平均相对误差分别减少32.97个百分点和18.67个百分点,且能够更精确地预测用户使用油耗,预测精度分别提高7%和4%。针对重型商用车细分市场构建行驶工况能更精确地刻画目标市场用户的车辆使用特征,提高了用户油耗的预测精度。
