The Fusion of Temporal Sequence with Scene Priori Information in Deep Learning Object Recognition

For some important object recognition applications such as intelligent robots and unmanned driving, images are collected on a consecutive basis and associated among themselves, besides, the scenes have steady prior features. Yet existing technologies do not take full advantage of this information. In order to take object recognition further than existing algorithms in the above application, an object recognition method that fuses temporal sequence with scene priori information is proposed. This method first employs YOLOv3 as the basic algorithm to recognize objects in single-frame images, then the DeepSort algorithm to establish association among potential objects recognized in images of different moments, and finally the confidence fusion method and temporal boundary processing method designed herein to fuse, at the decision level, temporal sequence information with scene priori information. Experiments using public datasets and self-built industrial scene datasets show that due to the expansion of information sources, the quality of single-frame images has less impact on the recognition results, whereby the object recognition is greatly improved. It is presented herein as a widely applicable framework for the fusion of information under multiple classes. All the object recognition algorithms that output object class, location information and recognition confidence at the same time can be integrated into this information fusion framework to improve performance.

Engineering of Self-Supported Electrocatalysts on a Three-Dimensional Nickel Foam Platform for Efficient Water Electrolysis

Economical water electrolysis requires highly active non-noble electrocatalysts to overcome the sluggish kinetics of the two half-cell reactions,oxygen evolution reaction,and hydrogen evolution reaction.Although intensive efforts have been committed to achieve a hydrogen economy,the expensive noble metal-based catalysts remain under consideration.Therefore,the engineering of self-supported electrocatalysts prepared using a direct growth strategy on three-dimensional(3D)nickel foam(NF)as a conductive substrate has garnered significant interest.This is due to the large active surface area and 3D porous network offered by these electrocatalysts,which can enhance the synergistic eff ect between the catalyst and the substrate,as well as improve electrocatalytic performance.Hydrothermal-assisted growth,microwave heating,electrodeposition,and other physical methods(i.e.,chemical vapor deposition and plasma treatment)have been applied to NF to fabricate competitive electrocatalysts with low overpotential and high stability.In this review,recent advancements in the development of self-supported electrocatalysts on 3D NF are described.Finally,we provide future perspectives of self-supported electrode platforms in electrochemical water splitting.

The response of roots and the rhizosphere environment to integrative cultivation practices in paddy rice

Integrative cultivation practices(ICPs)are essential for enhancing cereal yield and resource use efficiency.However,the effects of ICP on the rhizosphere environment and roots of paddy rice are still poorly understood.In this study,four rice varieties were produced in the field.Each variety was treated with six different cultivation techniques,including zero nitrogen application(0 N),local farmers’practice(LFP),nitrogen reduction(NR),and three progressive ICP techniques comprised of enhanced fertilizer N practice and increased plant density(ICP1),a treatment similar to ICP1 but with alternate wetting and moderate drying instead of continuous flooding(ICP2),and the same practices as ICP2 with the application of organic fertilizer(ICP3).The ICPs had greater grain production and nitrogen use efficiency than the other three methods.Root length,dry weight,root diameter,activity of root oxidation,root bleeding rate,zeatin and zeatin riboside compositions,and total organic acids in root exudates were elevated with the introduction of the successive cultivation practices.ICPs enhanced nitrate nitrogen,the activities of urease and invertase,and the diversity of microbes(bacteria)in rhizosphere and non-rhizosphere soil,while reducing the ammonium nitrogen content.The nutrient contents(ammonium nitrogen,total nitrogen,total potassium,total phosphorus,nitrate,and available phosphorus)and urease activity in rhizosphere soil were reduced in all treatments in comparison with the non-rhizosphere soil,but the invertase activity and bacterial diversity were greater.The main root morphology and physiology,and the ammonium nitrogen contents in rhizosphere soil at the primary stages were closely correlated with grain yield and internal nitrogen use efficiency.These findings suggest that the coordinated enhancement of the root system and the environment of the rhizosphere under integrative cultivation approaches may lead to higher rice production.

Full-domain collaborative deployment method of multiple interference sources and evaluation of its deployment effect

This paper realizes the full-domain collaborative deployment of multiple interference sources of the global satellite navigation system(GNSS)and evaluates the deployment effect to enhance the ability to disturb the attacker and the capability to defend the GNSS during navigation countermeasures.Key evaluation indicators for the jamming effect of GNSS suppressive and deceptive jamming sources are first created,their evaluation models are built,and their detection procedures are sorted out,as the basis for determining the deployment principles.The principles for collaboratively deploying multi-jamming sources are developed to obtain the deployment structures(including the required number,structures in demand,and corresponding positions)of three single interference sources required by collaboratively deploying.Accordingly,simulation and hardware-in-loop testing results are presented to determine a rational configuration of the collaborative deployment of multi-jamming sources in the set situation and further realize the full-domain deployment of an interference network from ground,air to space.Varied evaluation indices for the deployment effect are finally developed to evaluate the deployment effect of the proposed configuration and further verify its reliability and rationality.

A Study on the Assessment and Integration of Multi-Source Evapotranspiration Products over the Tibetan Plateau

Evapotranspiration(ET)is a crucial variable in the terrestrial water,carbon,and energy cycles.At present,a large number of multi source ET products exist.Due to sparse observations,however,great challenges exist in the evaluation and integration of ET products in remote and complex areas such as the Tibetan Plateau(TP).In this paper,the applicability of the multiple collocation(MC)method over the TP is evaluated for the first time,and the uncertainty of multisource ET products(based on reanalysis,remote sensing,and land surface models)is further analyzed,which provides a theoretical basis for ET data fusion.The results show that 1)ET uncertainties quantified via the MC method are lower in RS-based ET products(5.95 vs.7.06 mm month^(-1))than in LSM ET products(10.22 vs.17.97 mm month^(-1))and reanalysis ET estimates(7.27 vs.12.26 mm month-1).2)A multisource evapotranspiration(MET)dataset is generated at a monthly temporal scale with a spatial resolution of 0.25°across the TP during 2005-15.MET has better performance than any individual product.3)Based on the fusion product,the total ET amount over the TP and its patterns of spatiotemporal variability are clearly identified.The annual total ET over the entire TP is approximately 380.60 mm.Additionally,an increasing trend of 1.59±0.85 mm yr^(-1)over the TP is shown during 2005-15.This study provides a basis for future studies on water and energy cycles and water resource management over the TP and surrounding regions.

Effectiveness and safety of early lens extraction during par plana vitrectomy for proliferative diabetes retinopathy with mild cataract:a randomized clinical trial

●AIM:To evaluate the effectiveness and safety of early lens extraction during pars plana vitrectomy(PPV)for proliferative diabetic retinopathy(PDR)compared to those of PPV with subsequent cataract surgery.●METHODS:This multicenter randomized controlled trial was conducted in three Chinese hospitals on patients with PDR,aged>45y,with mild cataracts.The participants were randomly assigned to the combined(PPV combined with simultaneously cataract surgery,i.e.,phacovitrectomy)or subsequent(PPV with subsequent cataract surgery 6mo later)group and followed up for 12mo.The primary outcome was the change in best-corrected visual acuity(BCVA)from baseline to 6mo,and the secondary outcomes included complication rates and medical expenses.●RESULTS:In total,129 patients with PDR were recruited and equally randomized(66 and 63 in the combined and subsequent groups respectively).The change in BCVA in the combined group[mean,36.90 letters;95%confidence interval(CI),30.35–43.45]was significantly better(adjusted difference,16.43;95%CI,8.77–24.08;P<0.001)than in the subsequent group(mean,22.40 letters;95%CI,15.55–29.24)6mo after the PPV,with no significant difference between the two groups at 12mo.The overall surgical risk of two sequential surgeries was significantly higher than that of the combined surgery for neovascular glaucoma(17.65%vs 3.77%,P=0.005).No significant differences were found in the photocoagulation spots,surgical time,and economic expenses between two groups.In the subsequent group,the duration of work incapacity(22.54±9.11d)was significantly longer(P<0.001)than that of the combined group(12.44±6.48d).●CONCLUSION:PDR patients aged over 45y with mild cataract can also benefit from early lens extraction during PPV with gratifying effectiveness,safety and convenience,compared to sequential surgeries.

Phase-Based Optical Flow Method with Optimized Parameter Settings for Enhancing Displacement Measurement Adaptability

To enhance the applicability and measurement accuracy of phase-based optical flow method using complex steerable pyramids in structural displacement measurement engineering applications, an improved method of optimizing parameter settings is proposed. The optimized parameters include the best measurement points of the Region of Interest (ROI) and the levels of pyramid filters. Additionally, to address the issue of updating reference frames in practical applications due to the difficulty in estimating the maximum effective measurement value, a mechanism for dynamically updating reference frames is introduced. Experimental results demonstrate that compared to representative image gradient-based displacement measurement methods, the proposed method exhibits higher measurement accuracy in engineering applications. This provides reliable data support for structural damage identification research based on vibration signals and is expected to broaden the engineering application prospects for structural health monitoring.

重塑位于火山曲线右支的弱吸附金属单原子位点的配位环境及电子结构

金属单原子位点独特的电子结构使其在燃料电池阴极氧还原催化反应(ORR)的应用引起广泛兴趣.金属单原子中心作为催化剂的活性位点遵循Sabatier原则,即位于火山型曲线右侧的金属中心与ORR中间产物的结合能力弱,使中间产物难以被位点活化,与之相反,左侧的位点则与中间产物的结合力太强,使中间产物难以脱附.因此,构建中间产物结合强度适中的位点可以提高催化剂活性.研究表明,通过改变金属中心的配位环境可以调控金属的电子结构,进而调节对ORR中间产物的吸附能力,提高催化剂活性.例如,对于位于火山曲线左侧的FeN4位点,通过在配位原子中引入高电负性的基团,如OH,S,Cl,减弱其对ORR中间产物的结合强度,使其活性向右侧活性顶点移动.然而,目前还没有提出有效的策略来改善火山曲线右侧位点的弱吸附能力.例如,Pd和Pt的纳米催化剂具有较高的ORR活性,而其单原子MN4位点却对ORR呈惰性,原因为高电负性的N使M具有较高的电荷密度,使其对中间产物的吸附能力太弱而位于火山曲线的最右边,具有较差的本征活性.为了缓解此类金属与配位N之间的不匹配的问题,我们提出通过利用电负性低的C(χp=2.55)代替N(χp=3.04)配位,以提升弱吸附位点的本征活性.本文制备了Ir-N-C,Pd-N-C,Pt-N-C,Ir-C,Pd-C和Pt-C六种催化剂;X射线衍射、透射电极和球差电镜结果表明,催化剂不含金属颗粒;同步辐射结果表明,催化剂呈M-N/C配位形式存在,且价态为氧化态.飞行时间二次离子质谱法(ToF-SIMS)测试可以检测到MNXCY和MCX的位点结构,结合同步辐射结果,认为活性位点分别是IrNXC((4-X)),IrC4,PdN_(2)CX和PdN3CX,PdC4,PtN3C1和PtN4,PtC4.电化学结果表明,相比N配位的催化剂,C配位的催化剂具有更高的半波电位、起始电位及本征活性,表明C配位更适合配位金属Ir,Pd和Pt,证明本文策略的可行性.为了进一步研究催化活性提升的原因,本文采用密度泛函理论计算探究催化机理,根据实验结果(X射线吸附光谱和ToF-SIMS)模拟了催化剂的活性位点结构,并计算反应中间产物的吸附能ΔGOH*.将ΔGOH*作为横坐标,反应的起始电位即催化活性作为纵坐标,绘制图谱得到火山型曲线.结果表明,相比N配位的金属位点,C配位的金属位点向强吸附端移动并靠近活性顶点,与实验结果一致,说明催化活性的提升是因为配位环境的改变改善了位点吸附能力.随后,通过计算活性位点的Bader电荷密度探究配位环境对电子结构的调控.结果显示,低电负性的C由于吸电子能力弱于高电负性的N,使MCX位点具有较低的Bader电荷密度,从而具有较强的中间产物吸附能力,进而提高催化活性.综上,本文提出了一个普遍性的原则,通过利用低电负性的元素配位调节具有弱结合能的金属(不仅是Ir,Pd,Pt)位点活性,为不同性质的金属匹配合适的配位环境,以实现高催化活性.

The decisive role of adsorbed OH^(*)in low‐potential CO electro‐oxidation on single‐atom catalytic sites

CO impurity-induced catalyst deactivation has long been one of the biggest challenges in proton-exchange membrane fuel cells,with the poisoning phenomenon mainly attributed to the overly strong adsorption on the catalytic site.Here,we present a mechanistic study that overturns this understanding by using Rh-based single-atom catalysis centers as model catalysts.We precisely modulated the chelation structure of the Rh catalyst by coordinating Rh with C or N atoms,and probed the reaction mechanism by surface-enhanced Raman spectroscopy.Direct spectroscopic evidence for intermediates indicates that the reactivity of adsorbed OH^(*),rather than the adsorption strength of CO^(*),dictates the CO electrocatalytic oxidation behavior.The RhN_(4)sites,which adsorb the OH^(*)intermediate more weakly than RhC4 sites,showed prominent CO oxidation activity that not only far exceeded the traditional Pt/C but also the RhC4 sites with similar CO adsorption strength.From this study,it is clear that a paradigm shift in future research should be considered to rationally design high-performance CO electro-oxidation reaction catalysts by sufficiently considering the water-related reaction intermediate during catalysis.

Therapeutic effects of isoquercetin on ovariectomy-induced osteoporosis in mice

Bone marrow mesenchymal stem cells(BMSCs)are non-hematopoietic multipotent stem cells capable of differentiating into mature cells.Isoquercetin,an extract from natural sources,has shown promise as a potential treatment for osteoporosis.To investigate the therapeutic effects of isoquercetin on osteoporosis,bone marrow mesenchymal stem cells(BMSCs)were cultured in vitro,and osteogenesis or adipogenesis was induced in the presence of isoquercetin for 14 days.We evaluated cell viability,osteogenic and adipogenic differentiation,as well as mRNA expression levels of Runx2,Alpl,and OCN in osteoblasts,and mRNA expression levels of Pparγ,Fabp4,and Cebpαin adipocytes.The results showed that isoquercetin dose-dependently increased cell viability and promoted osteogenic differentiation,as evidenced by Alizarin Red and alkaline phosphatase staining and mRNA expression levels of Runx2,Alpl,and OCN in osteoblasts(P<0.05).In contrast,isoquercetin inhibited adipogenic differentiation and decreased the mRNA expres-sion levels of Pparγ,Fabp4,and Cebpαin adipocytes(P<0.05).In vivo,isoquercetin treatment increased bone quan-tity and density in an osteoporosis model mice group,as determined byμCT scanning and immunohistochemistry(P<0.05).These findings suggest that isoquercetin may have therapeutic potential for osteoporosis by promoting the proliferation and differentiation of BMSCs towards osteoblasts while inhibiting adipogenic differentiation.

Network pharmacology and verification experiment-based prediction of active components and potential targets of Alpiniae Oxyphyllae Fructus-Saposhnikoviae Radix(Yizhiren-Fangfeng)for treatment of diabetic kidney disease

Background:In this study,we analyzed the potential active components,related crucial targets and possible signaling pathway mechanisms of Alpiniae Oxyphyllae Fructus and Saposhnikoviae Radix(AOF-SR)herb pairs in the treatment of diabetic kidney disease(DKD)using network pharmacology and verification experiments.Methods:The active compounds and potential targets of AOF-SR were derived from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform,The Encyclopedia of Traditional Chinese Medicine,and PubChem databases,and the potential therapeutic targets of DKD were derived from the OMIM,Drugbank,and DisGeNET databases.The“compounds-diseases-targets”network was constructed using Cytoscape 3.6.0.ClusterMaker functionality in Cytoscape is being used to screen important targets for AOF-SR treatment of DKD.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis of important targets were performed using DAVID database.In addition,according to the predicted results of network pharmacology,HK-2 cells were used to construct DKD model for verification experiment.HK-2 cells were divided into control group,high glucose(HG)group and AOF-SR(HG+AOF-SR)group to detect survival rate and expression of key proteins in NF-κB and PI3K/Akt signaling pathways.Results:A total of 38 compounds were selected from AOF-SR,of which 23 were Alpiniae Oxyphyllae Fructus and 15 were Saposhnikoviae Radix.Through enrichment analysis of 82 important targets,88 signaling pathways were identified;some of these pathways,such as the NF-κB,PI3K-Akt,IL-17,and JAK/STAT signaling pathways,regulate the pathological process of DKD.In verification experiment,the HK-2 cells survival rate was higher in the HG+AOF-SR group than in the HG group(P<0.05).Moreover,western blotting results showed that the expression levels of NF-κB,p-PI3K,and p-Akt in HG+AOF-SR group were significantly lower than those in HG group(P<0.05).Conclusion:Overall,this study revealed the active compounds,important targets and possible mechanisms of AOF-SR treatment for DKD,and conducted preliminary verification experiments on its correctness,provided novel insights into the treatment of DKD by AOF-SR.

去整合素金属蛋白酶8在食管鳞癌的表达及与病理特征的关系

目的探讨去整合素金属蛋白酶8(ADAM8)在食管鳞癌的表达及与病理分级和预后的关系。方法选取河南科技大学第一附属医院因食管鳞癌行手术治疗患者47例。免疫组织化学法检测ADAM8的表达;统计患者病理特征并进行术后随访,分析ADAM8与病理特征及预后的关系。结果食管鳞癌组织中ADAM8高表达比例与正常组织比较,差异有统计学意义(P<0.05),食管鳞癌组织中ADAM8高表达比例大于正常组。肿瘤高分级患者ADAM8表达高于低分级肿瘤患者,TNM分期Ⅲ、Ⅳ期患者ADAM8表达高于Ⅰ、Ⅱ期患者,淋巴结转移患者ADAM8表达高于无淋巴结转移患者,差异均有统计学意义(P<0.05)。癌组织中ADAM8高表达患者与ADAM8低表达患者,术后2年生存率的比较,差异有统计学意义(P<0.05)。结论ADAM8在食管鳞癌中表达上调,ADAM8表达水平对判断食管鳞癌病理特征与预后具有一定参考价值。

科学知识与科学精神的有机融合——以大学通识课程“走近诺贝尔化学奖(双语课程)”为例

以"走近诺贝尔化学奖(双语课程)"为例,探讨理工类大学通识教育课程的设计理念和实践探索。

采用薄层氮化碳促进的高性能钯基催化剂用于甲酸分解制氢

自第一次工业革命以来,传统的化石能源(煤炭,石油等)一直是能源消费的主体。但是,随着社会的进步和技术的发展,能耗不断增加。但是化石能源不仅储量有限,而且还会引起严重的环境问题(环境污染和温室效应)。因此,清洁和可持续能源的研究与开发尤为重要,氢能是研究的重点之一。由于氢具有高能量密度、清洁和可持续性的特点,因而成为了最有前景的能源载体。然而,氢气的储存和运输困难严重限制了其在质子交换膜燃料电池中的实际应用。作为液态氢存储材料之一,甲酸在催化剂存在下于室温下即可分解。另外,甲酸分解制氢的反应中不会释放有毒有害气体,对环境友好。用于甲酸分解(FAD)的高效催化剂是制氢的关键材料。本文制备了由薄层氮化碳促进的高性能钯(Pd)基催化剂,用于甲酸分解。首先,通过一步法直接煅烧三聚硫氰酸,以获得氮化碳(C_(3)N_(4)-S),然后制备以C_(3)N_(4)-S为载体的Pd基FAD催化剂(Pd/C_(3)N_(4)-S)。在三聚硫氰酸的热解过程中,―SH基团的溢出具有剥离作用,因此形成的C_(3)N_(4)为破碎的薄层,具有较大的比表面积和孔体积。由于改善的比表面积和孔体积以及大量的缺陷附着位点,C_(3)N_(4)-S载体可以有效地分散Pd纳米颗粒。此外,由于载体和金属之间的电子效应,该载体可以有效地调节催化剂表面上的Pd^(2+)含量。因此,Pd/C_(3)N_(4)-S表现优异的FAD性能。在30°C下,该催化剂可将甲酸有效分解为CO_(2)和H_(2),转换频率(TOF值)和质量比活性分别达到了2083 h−1和19.52 mol·g−1·h−1。并且气相色谱测试结果表明,气体产物中不含CO,表明Pd/C_(3)N_(4)-S催化剂具有优异的选择性。另外,Pd/C3N4-S催化剂也具有良好的稳定性。经过4次循环测试,催化性能仅下降了不到10%。该研究为研究高性价比、制备方法简单的甲酸制氢催化剂提供了一定的指导作用。

快充式经鼻湿化高流量通气在肥胖患者无痛胃镜检查中的应用效果

目的比较鼻导管纯吸氧和快充式经鼻湿化高流量通气在肥胖患者无痛胃镜检查中的应用效果。方法选取2019年1月-2021年1月该院行无痛胃镜检查的118例患者作为研究对象,所有患者体重指数(BMI)≥28 kg/m^(2),采用随机数表法将其分为两组,各59例。观察组和对照组分别给予快充式经鼻湿化高流量通气和鼻导管纯吸氧。比较两组患者无痛胃镜检查麻醉前(T_(0))、麻醉5 min(T_(1))、苏醒5 min(T_(2))的血流动力学水平、无痛胃镜检查情况、缺氧相关不良事件及干预情况、不良反应和患者满意度。结果观察组T_(1)和T_(2)时点平均动脉压(MAP)和经皮动脉血氧饱和度(SpO_(2))高于对照组,心率(HR)低于对照组,观察组T_(1)时点呼吸频率(RR)高于对照组,差异均有统计学意义(P<0.05)。观察组检查时间短于对照组,亚临床呼吸抑制和缺氧发生率低于对照组,开放通气、面罩通气和气管内插管机械通气使用率低于对照组,不良反应总发生率低于对照组,观察组对胃镜检查满意度为79.66%,明显高于对照组的57.63%,差异均有统计学意义(P<0.05)。结论快充式经鼻湿化高流量通气应用于肥胖患者无痛胃镜检查中,能够稳定患者的血流动力学水平,缩短检查时间,提高检查成功率,减少缺氧相关不良事件,降低不良反应发生率,提高患者的检查满意度。

Expression and significance of homeodomain protein Cdx2 in gastric carcinoma and precancerous lesions

AIM： To investigate the expression and significance of caudal-related homeobox transcription factor （Cdx2） in gastric carcinoma （GC） and precancerous lesions. METHODS： The expression of Cdx2 in GC, precancer- ous lesions and normal gastric mucosa were detected using immunohistochemical method. Hematoxylin and eosin staining, alcian blue/periodic acid-schiff and high iron diamine/alcian blue staining were used to classify intestinal metaplasia （IM） and GC. RESULTS： Cdx2 was not detected in normal gas- tric mucosa. Cdx2 expression was detected in 87.1% （101/116） of IM, 50% （36/72） of dysplasia and 48.2% （41/85） of GC. The Cdx2-expressing cells in IM were more prevalent than in dysplasia and carcinoma （P 〈 0.05）. There was no relationship between Cdx2 ex- pression and the classification of IM or the degree of dysplasia. Expression of Cdx2 was significantly higher in intestinal-type carcinoma than in diffuse and mixed- type carcinoma （P 〈 0.05）. Positive expression of Cdx2was mainly found in moderately to well differentiated GC. There was a negative association between nuclear Cdx2 expression and lymph node metastasis and tumor, nodes, metastasis stage of GC （P 〈 0.05）. The patients with Cdx2-positive expression showed a higher survival rate than those with Cdx2-negative expression （P = 0.038）. Multivariate analysis revealed that the expres- sion of Cdx2 and lymph node metastasis were indepen- dent prognostic indicators of GC （P 〈 0.05）.

低铱酸性氧析出电催化剂的研究进展

开发高性能、低成本的氧析出反应(OER)电催化剂是促进质子交换膜水电解(PEMWE)制氢规模化应用的关键。迄今为止,OER催化剂的最佳选项仍为贵金属铱(Ir),但其仍存在活性不足和储量稀缺的问题,进而增加了材料成本和电力成本。因此,开发低Ir载量、高活性和稳定性间距,且能够满足PEMWE设备中大电流密度和长期运行要求的OER催化剂是十分必要的。这些目标的实现需要深入理解酸性OER机制、明晰材料设计方法,并建立可靠的性能评估指标(特别是对耐久性的评估)。综上,本文首先系统总结了目前被广泛接受的酸性OER活性表达机制(即吸附析出机制、晶格氧氧化机制和多活性中心机制)和失活机制(即活性物种溶解、晶相和形态演化、催化剂脱落和活性位点阻塞),为催化剂的微观结构设计提供指导。其次,我们讨论了最近报道的几类低铱OER催化剂,包括多金属合金氧化物、负载型催化剂、具有特殊空间结构的催化剂和单位点催化剂,并重点描述低Ir催化剂中的性能如何得以调控以及其中潜在的构效关系。随后,我们介绍了常用的催化剂稳定性评价指标、催化剂失活表征技术以及模拟PEMWE实际操作条件的催化剂寿命测试方法,希望为催化剂筛选提供依据。最后,针对未来可用于PEMWE体系的低铱OER催化剂的探索提出了一些可行建议。

Tuning the selectivity of photoreduction of CO2 to syngas over Pd/layered double hydroxide nanosheets under visible light up to 600 nm

Photocatalytic reduction of CO2 with H2 O to syngas is an effective way for producing high value-added chemical feedstocks such as methanol and light olefins in industry.Nevertheless,the precise control of CO/H2 ratio from photocatalytic CO2 reduction reaction still poses a great challenge for the further application.Herein,we prepared a series of highly efficient heterostructure based on highly dispersed palladium supported on ultrathin Co Al-layered double hydroxide(LDH).In conjunction with a Ru-complex sensitizer,the molar ratios of CO/H2 can be tuned from 1:0.74 to 1:3 under visible-light irradiation(λ>400 nm).More interestingly,the syngas can be obtained under light irradiation atλ>600 nm.Structure characterization and density functional theory calculations revealed that the remarkable catalytic activity can be due to the supported palladium,which improved the charge transfer efficiency.Meanwhile,more H atoms were used to generate H2 on the supported palladium for further tunable CO/H2 ratio.This work demonstrates a new strategy for harnessing abundant solar-energy to produce syngas from a CO2 feedstock.

Surface interaction between Pd and nitrogen derived from hyperbranched polyamide towards highly effective formic acid dehydrogenation

Hydrogen production from formic acid decomposition(FAD)is a promising means of hydrogen energy storage and utilization in fuel cells.Development of efficient catalysts for dehydrogenation of formic acid is a challenging topic.The surface chemical and electronic structure of the active catalysis components is important in formic acid decomposition at room-temperature.Here,the pyrdinic-nitrogen doped catalysts from hyperbranched polyamide were prepared via in situ polymerization reaction process by using activated carbon as a support.Because of the introduction of the polymer,the particles of the catalysts were stabilized,and the average particle diameter was only 1.64 nm.Under mild conditions,the catalysts activities were evaluated for FAD.The optimized Pd-N30/C catalyst exhibited high performance achieving almost full conversion,with a turnover frequency of 3481 h^-1 at 30℃.

Quantitative‑Profling Method of Serum Steroid Hormones by Hydroxylamine‑Derivatization HPLC-MS

A sensitive and rapid high performance liquid chromatography-mass spectrometry(HPLC-MS)method was developed and validated for simultaneous quantifcation of ten steroid hormones,including estrogens,androgens,progesterones,and corticosteroids four classes of steroids.The following ten steroid hormones were analyzed:progesterone,21-deoxycortisol,estrone,4-androstenedione,testosterone,dihydro-testosterone,androstenone,dehydroepiandrosterone,corticosterone and cortisone.Stable deuterated isotopes were used as internal standards for quantifcation.Sample preparation with and without derivatization were performed after liquid-liquid extraction,and the corresponding results were compared according to sensitivity and selectivity.Hydroxylamine derivatization was found to improve the ionization efciency of the analytes for electrospray ionization MS analysis.The gradient of mobile phase and experimental parameters for HPLC separation were optimized.The lower limits of quantifcation were in the range of 0.05-5 ng mL^(−1) with wide linear range for the ten steroid hormones.The intra-day precision<11.1%and recovery of 84.5-120% with negligible matrix efect were achieved,where within the acceptance limits of the FDA guideline.Total HPLC-MS analysis time was 6 min.This method enables simultaneous quantifcation of steroids in human serum.It will be helpful for the serum steroid profling in order to understand various endocrinology diseases.