Rh/Al_(2)O_(3)催化剂在丙烷脱氢反应中的表面变化

丙烯是一种重要的化工原料,需求量较大且逐年增加.丙烷脱氢(PDH)是一种高效的生产丙烯过程,正逐步取代石脑油裂解成为重要的丙烯生产工艺.开发高效且稳定的PDH催化剂将对PDH工业发展起到积极的推动作用.Rh因其较好的C-H键活化能力,展现出作为PDH催化剂的巨大潜力,但关于Rh应用于PDH的报道较少.明确Rh物种尺寸对PDH产物选择性的影响,对后续设计高效且稳定的Rh基PDH催化剂至关重要.多相催化反应主要发生在催化剂的表面,因此,催化剂的表面状态对其催化性能具有重要的影响.在催化反应过程中,一些催化剂的表面状态会发生显著变化,这些变化会导致活性、产物选择性明显变化.通过采用(准)原位表面研究手段,能够清晰地了解催化剂在反应过程中的表面变化,这对于建立催化剂结构与反应性能之间的构效关系具有非常重要的意义.本文通过沉积-沉淀法制备了不同负载量的Rh/Al_(2)O_(3)催化剂,旨在探究Rh物种尺寸对PDH产物选择性的影响.球差电镜(AC-HAADF-STEM)观察显示,Rh物种以团簇和单原子的形式共存于Al_(2)O_(3)载体上.进一步通过准原位X射线光电子能谱(XPS)证实了不同化学态的Rh物种.通过固定床反应器对Rh/Al_(2)O_(3)催化剂的PDH性能进行测试,结果表明,催化剂在反应初始阶段需要经历诱导期.在此期间,甲烷的选择性显著降低,而丙烯的选择性显著升高,同时,丙烷的转化率显著降低.碳平衡计算表明,诱导期内产生了大量积碳.采用准原位XPS、低能离子散射谱(LEIS)和CO吸附红外光谱(CO-FTIR)研究了Rh/Al_(2)O_(3)催化剂在诱导期的表面变化.结果表明,在反应初始阶段,催化剂表面有大量积碳产生,这些积碳主要聚集在Rh物种表面,覆盖了Rh团簇,而Rh单原子则保持暴露状态,并作为PDH反应的活性中心.AC-HAADF-STEM结果表明,PDH反应4 h后,仍有Rh单原子存在于催化剂表面.结合Rh/Al_(2)O_(3)催化剂的PDH性能和准原位表征结果认为,丙烷在Rh团簇表面发生C-C键断裂反应,生成甲烷和积碳.积碳对Rh团簇的覆盖抑制了丙烷裂解反应,导致甲烷的选择性在诱导期显著降低;而Rh单原子则仍然暴露,具有催化PDH反应活性,并且是高选择性地生成丙烯的位点.该选择性的差异由丙烯在不同尺寸Rh物种上的吸附方式不同引起的,在Rh团簇表面以di-σ键吸附方式为主,吸附强度较强,丙烯不易脱附,并进一步发生裂解产生甲烷和积碳;而在Rh单原子上,丙烯以π键吸附方式存在,吸附强度较弱,不易发生副反应.对反应后的Rh/Al_(2)O_(3)催化剂进行分析,发现积碳主要为碳氢化合物和石墨碳,且随着反应进行,积碳从Rh团簇表面向Al_(2)O_(3)载体上转移.综上所述,本文通过使用准原位XPS,LEIS和CO-FTIR等技术探究了Rh/Al_(2)O_(3)催化剂在PDH反应中的表面变化,揭示了Rh物种尺寸对PDH产物选择性的影响.结果表明,Rh单原子对丙烯选择性有利,而在Rh团簇表面PDH产物主要为甲烷并产生积碳,同时积碳导致了催化剂在反应初始阶段的快速失活.本工作为后续高效Rh基PDH催化剂的设计提供参考.

Durable Ru Nanocrystal with HfO_(2)Modification for Acidic Overall Water Splitting

Durable and efficient bi-functional catalyst,that is capable of both oxygen evolution reaction and hydrogen evolution reaction under acidic condition,are highly desired for the commercialization of proton exchange membrane water electrolysis.Herein,we report a robust L-Ru/HfO_(2)heterostructure constructed via confining crystalline Ru nanodomains by HfO_(2)matrix.When assembled with a proton exchange membrane,the bi-functional L-Ru/HfO_(2)catalyst-based electrolyzer presents a voltage of 1.57 and 1.67 V to reach 100 and 300 mA cm^(-2)current density,prevailing most of previously reported Ru-based materials as well as commercial Pt/C||RuO_(2)electrolyzer.It is revealed that the synergistic effect of HfO_(2)modification and small crystalline domain formation significantly alleviates the over-oxidation of Ru.More importantly,this synergistic effect facilitates a dual-site oxide path during the oxygen evolution procedure via optimization of the binding configurations of oxygenated adsorbates.As a result,the Ru active sites maintain the metallic state along with reduced energy barrier for the rate-determining step(^(*)O→^(*)OOH).Both of water adsorption and dissociation(Volmer step)are strengthened,while a moderate hydrogen binding is achieved to accelerate the hydrogen desorption procedure(Tafel step).Consequently,the activity and stability of acidic overall water splitting are simultaneously enhanced.

Unsaturated bi-heterometal clusters in metal-vacancy sites of 2D MoS2 for efficient hydrogen evolution

The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation strategies.Hence,a robust method is proposed to form unsaturated heteroatom clusters via the metal-vacancy restraint mechanism,which can precisely regulate the bonding and valence state of heterometal atoms doped in 2D molybdenum disulfide.The unsaturated valence state of heterometal Pt and Ru cluster atoms form a spatial coordination structure with Pt–S and Ru–O–S as catalytically active sites.Among them,the strong binding energy of negatively charged suspended S and O sites for H+,as well as the weak adsorption of positively charged unsaturated heterometal atoms for H*,reduces the energy barrier of the hydrogen evolution reaction proved by theoretical calculation.Whereupon,the electrocatalytic hydrogen evolution performance is markedly improved by the ensemble effect of unsaturated heterometal atoms and highlighted with an overpotential of 84 mV and Tafel slope of 68.5 mV dec^(−1).In brief,this metal vacancy-induced valence state regulation of heterometal can manipulate the coordination structure and catalytic activity of heterometal atoms doped in the 2D atomic lattice but not limited to 2D nanomaterials.

Engineering electrolyte additives for stable zinc-based aqueous batteries:Insights and prospects

Zn-based aqueous batteries(ZABs) are gaining widespread popularity due to their low cost and high safety profile. However, the application of ZABs faces significant challenges, such as dendrite growth and parasitic reactions of metallic Zn anodes. Therefore, achieving high-energy–density ZABs necessitates addressing the fundamental thermodynamics and kinetics of Zn anodes. Various strategies are available to mitigate these challenges, with electrolyte additive engineering emerging as one of the most efficient and promising approaches. Despite considerable research in this field, a comprehensive understanding of the intrinsic mechanisms behind the high performance of electrolyte additives remains limited. This review aims to provide a detailed introduction to functional electrolyte additives and thoroughly explore their underlying mechanisms. Additionally, it discusses potential directions and perspectives in additive engineering for ZABs, offering insights into future development and guidelines for achieving high-performance ZABs.

Structural characteristics of phenylboronic acid-modified astaxanthin ester and its effect on DSS-induced ulcerative colitis by blocking reactive oxygen species and maintaining intestinal homeostasis

A novel and reactive oxygen species(ROS)responsive astaxanthin phenylboronic acid derivative(AstaDPBA)was constructed by grafting phenylboronic acid(PBA)onto astaxanthin succinate diester(AstaD),and its chemical structure and physicochemical property were identified.AstaD-PBA could effectively improve the ROS quenching ability in the lipopolysaccharide(LPS)-induced RAW264.7 cell inflammation model.Then,the bioactivity of AstaD-PBA was studied by 4 zebrafish ROS-responsive infl ammatory models induced by LPS,copper(Cu^(2+)),high-fat diet,and dextran sodium sulfate(DSS).The results suggest that AstaD-PBA might have high biosafety and the best effect on ulcerative colitis(UC)induced by DSS.Furtherly,AstaDPBA significantly alleviated and treated weight loss and colonic shrinkage,inhibited infl ammatory cytokines,and maintained microbiota homeostasis to improve UC in C57BL/6J mice.Alistipes and Oscillibacter were expected to be considered UC marker fl ora according to the Metastats analysis and Pearson correlation Mantel test(P<0.01)of 16S rRNA gene sequencing data.In conclusion,AstaD-PBA has been promised to be a functional compound to improve UC and maintain intestinal microbiota homeostasis.

Mapping the antiparallel aligned domain rotation by microwave excitation

The evolution process of magnetic domains in response to external fields is crucial for the modern understanding and application of spintronics.In this study,we investigated the domain rotation in stripe domain films of varying thicknesses by examining their response to microwave excitation in four different orientations.The resonance spectra indicate that the rotation field of stripe domain film under an applied magnetic field approaches the field where the resonance mode of sample changes.The saturation field of the stripe domain film corresponds to the field where the resonance mode disappears when measured in the stripe direction parallel to the microwave magnetic field.The results are reproducible and consistent with micromagnetic simulations,providing additional approaches and techniques for comprehending the microscopic mechanisms of magnetic domains and characterizing their rotation.

A perspective on the key factors of safety for rechargeable magnesium batteries

Rechargeable Mg batteries(RMBs)have become one of the best subsitutes for lithium-ion batteries due to the high volumetric capacity,abundant resources,and uniform plating behavior of Mg metal anode.However,the safety hazard induced by the formation of high-modulue Mg dendrites under a high current density(10 mA cm^(-1))was still revealed in recent years.It has forced researchers to re-examine the safety of RMBs.In this review,the intrinsic safety factors of key components in RMBs,such as uneven plating,pitting and flammability of Mg anode,heat release and crystalline water decomposition of cathode,strong corrosion,low oxidition stability and flammability of electrolytes,and soforth,are systematacially summarized.Their origins,formation mechanisms,and possible safety hazards are deeply discussed.To develop high-performance Mg anode,current strategies including designing artificial SEI,three-dimensional substrates,and Mg alloys are summarized.For practical electrolytes,the configurations of boron-centered anions and simple Mg salts and the functionalized solvent with high boiling point and low flammability are suggested to comprehensively design.In addition,the future study should more focus on the investigation on the thermal runaway and decomposition of cathode materials and separa-tors.This review aims to provide fundamental insights into the relationship between electrochemistry and safety,further promoting the sustainable development of RMBs.

Intelligent architecture modeling for multilevel fluvial reservoirs based on architecture interface and elements

At present,the architecture modeling method of fluvial reservoirs are still developing.Traditional methods usually use grids to characterize architecture interbeds within the reservoir.Due to the thin thickness of this type of the interlayers,the number of the model grids must be greatly expanded.The number of grids in the tens of millions often makes an expensive computation;however,upscaling the model will generate a misleading model.The above confusion is the major reason that restricts the largescale industrialization of fluvial reservoir architecture models in oilfield development and production.Therefore,this paper explores an intelligent architecture modeling method for multilevel fluvial reservoirs based on architecture interface and element.Based on the superpositional relationship of different architectural elements within the fluvial reservoir,this method uses a combination of multilevel interface constraints and non-uniform grid techniques to build a high-resolution 3D geological model for reservoir architecture.Through the grid upscaling technology of heterogeneous architecture elements,different upscaling densities are given to the lateral-accretion bedding and lateral-accretion bodies to simplify the model gridding.This new method greatly reduces the number of model grids while ensuring the accuracy of lateral-accretion bedding models,laying a foundation for large-scale numerical simulation of the subsequent industrialization of the architecture model.This method has been validated in A layer of X oilfield with meandering fluvial channel sands as reservoirs and B layer of Y oilfield with braided river sands as reservoirs.The simulation results show that it has a higher accuracy of production history matching and remaining oil distribution forecast of the targeted sand body.The numerical simulation results show that in the actual development process of oilfield,the injected water will not displace oil in a uniform diffusive manner as traditionally assumed,but in a more complex pattern with oil in upper part of sand body being left behind as residual oil due to the influences of different levels of architecture interfaces.This investigation is important to guiding reservoir evaluation,remaining oil analysis,profile control and potential tapping and well pattern adjustment.

新生儿眼底病变筛查及视网膜出血的影响因素

目的:筛查统计新生儿眼底病变的基本情况,并探讨新生儿视网膜出血的影响因素。方法:收集2016-01-01/2018-05-31于我院产科病房及新生儿重症监护病房采用儿童数字化广域成像系统(RetcamⅢ)进行眼底筛查的新生儿,记录其性别、胎龄、分娩方式、窒息史、母孕史等临床资料,并对筛查结果进行统计分析。结果:本研究纳入新生儿289例,其中早产儿97例,足月儿192例。检出眼底病变者64例(22. 1%),其中视网膜出血者34例(11. 8%)、早产儿视网膜病变者23例(8. 0%)。单因素分析发现,胎龄、分娩方式、经阴产情况、有无窒息史、有无母孕期妊高征史、分娩史是新生儿视网膜出血的影响因素。多因素Logistic回归分析显示,早产儿、经阴道分娩、有窒息史、母孕期妊高征史是新生儿视网膜出血的高危因素。结论:新生儿视网膜出血发生率较高,其与胎龄、分娩方式、窒息史、母孕期妊高征史等多种因素相关,临床诊疗中应高度重视新生儿眼底病变的筛查。

骨来源恶性肿瘤临床疗效的评估

目的:通过现有实体瘤临床评估体系,对骨来源恶性肿瘤术前化疗前后的影像学资料进行总结,对比病理学评估结果,进一步提出并完善适合骨来源恶性肿瘤疗效的临床评估体系。方法:回顾性分析自2014年6月至2017年3月就诊于北京大学人民医院的190例连续病例,最后纳入研究157例,通过病理学Huvos分级将病例进行分组,对术前化疗前后的临床资料(肿瘤最大径变化、代谢参数的变化,以及一些公认的描述性参数)进行差异性检验及通过受试者工作曲线(receiver operating characteristic curve,ROC)计算肿瘤各项参数的变化率对术前化疗病理反应的ROC曲线下面积,并判断病理学分级的截点。结果:对原发肢体骨包含软组织包块的病例,判断坏死率为100%、90%及50%的最大径变化率截点分别为86%、50.7%和0.02%,骨扫描的T/B值变化率对坏死率预测效果不好,而PET/CT的SUVmax变化率对应坏死率为90%和50%的截点分别为60.7%和31.4%;而骨性边界变清晰及骨性密度增高为90%以上的病理学特异性表现形式。对不含软组织包块的原发纯骨内病变的病例,尚未发现有意义的临床评估指标。对中轴骨(包括颌面骨、脊柱及骨盆等)的病灶,由于病例数少,临床评估的截点目前区分度不大。结论:本研究对骨来源肿瘤的疗效临床评估提出了更具体的定义和不同病理学分级的界值,该临床评估体系的完善需通过前瞻、多中心、大宗数据进一步验证和讨论。

Analgesic Effect of Combined Spinal-Epidural Anesthesia and its Effect on TNF-α and CRP Levels in Elderly Patients with Hip Fracture During Surgical Treatment

Objective:To observe the analgesic effect of combined spinal and epidural anesthesia on older patients undergoing hip fracture surgery.Method:One hundred and twenty elderly hip fracture surgery patients treated in our hospital from January 2021 to December 2022 were selected and randomly divided into two groups,with 60 cases in the experimental group and 60 in the control group.The experimental group was given combined spinal-epidural anesthesia intervention measures,while the control group was given epidural anesthesia intervention measures.The analgesic effect,tumor necrosis factor-alpha(TNF-α),C-reactive protein(CRP)levels,and other observation indicators were analyzed after anesthesia intervention.Result:After the intervention,the analgesic effect and the evaluation results of the subjects in the experimental group were better than those in the control group(P<0.05);the obtained values of TNF-αand CRP levels in the experimental group were higher than those of the control group(P<0.05).Conclusion:The combined spinal-epidural anesthesia intervention demonstrated positive outcomes.The analgesic effect of patients during surgery and their inflammatory factor levels improved,which makes this intervention worthy of clinical application and promotion.

输尿管镜下输尿管长段撕脱的处理和思考

目的探讨输尿管镜手术致输尿管长段撕脱的处理方法。方法对3例输尿管长段分别为18、20和21 cm撕脱患者进行诊治,1例行膀胱瓣管残端吻合术,1例行膀胱瓣管肾盂吻合术,1例行回肠代输尿管术,均于腔内放置双J管。结果行膀胱瓣管输尿管残端吻合术的患者于术后7个月取出双J管,1个月后复查无肾积水,无其他并发症,恢复良好。行膀胱瓣管肾盂吻合术的患者,术后3个月取出双J管,1个月后复查,出现吻合口旁边囊肿,后期行自体肾移植术。行回肠代输尿管术的患者,于术后6个月取出双J管,1个月后复查无肾积水,恢复良好。结论输尿管镜下输尿管长段撕脱需及时行膀胱瓣管代输尿管术、回肠代输尿管术或自体肾移植术,需在术后6个月以后考虑取出双J管,使输尿管损伤得到最佳处理效果。

A Generalization of NTRUEncrypt —Cryptosystem Based on Ideal Lattice

The purpose of this article is to extend the theory of circulant matrix to general ideal matrix, and to construct more general NTRU cryptosystem combined with the φ-cyclic code. To understand our construction, first we discuss a more general form of the ordinary cyclic code, namely φ-cyclic code, which firstly appeared in [1] and [2], thus we give a more generalized NTRUEncrypt by replacing finite field with real number field R.

Study on Pulp Grade of Iron Ore Concentrate by Monte Carlo

When energy distribution X-ray fluorescence analysis method (EDXRF) is used to measure the pulp grade of iron concentrate, the parameters such as the location of radioactive source, detector, the particle size of the iron concentrate, and the concentration of the iron concentrate slurry, etc. have a greater influence on the measurement results. In order to more accurately measure the grade of iron ore pulp, the Monte Carlo method was used to study the different pulp grades of samples of the iron ore concentrate under different conditions such as the location of radioactive source, detector, the particle size of the iron concentrate, and the concentration of the iron concentrate slurry. By studying the relationship between different influencing factors and counting rate, the error of the actual measurement time and the pulp grade of iron concentrate can be reduced. The pulp grade of iron concentrate is improved, and the in-situ EDXRF analysis of iron concentrate slurry is more in line with the actual grade.

Overview of Industrial Materials Detection Based on Prompt Gamma Neutron Activation Analysis Technology

Prompt gamma neutron activation analysis (PGNAA) is a non-destructive online measurement nuclear analysis method. With its unique advantages, it has been widely used in online analysis of industrial materials such as coal, cement, and minerals in recent years. However, there are many kinds of literature on PGNAA in the field of industrial materials detection, and there are still a few concluding articles. To this end, based on the principle of PGNAA online analysis, the status quo and development of the real-time online detection of industrial material components in the field are reviewed and discussed by consulting a large number of domestic and foreign PGNAA related literature and data, to facilitate the reference of relevant scientific researchers.

腹腔镜辅助消化道重建对胃癌患者的应用及患者CyclinD1蛋白表达的影响

背景目前我国胃癌(gastric cancer, GC)的发病率较高且呈逐年上升的趋势,且对GC患者最有效的治疗手段就是胃大部切除或者胃全切,那么患者术中就要面临消化道重建的问题.随着腔镜技术的不断发展, GC患者术中使用腔镜技术进行消化道重建已经十分常见.但是对于腔镜辅助消化道重建是否能达到传统消化道重建的疗效,并不十分确切,故针对腔镜辅助消化道重建的疗效做出研究.目的探讨腹腔镜辅助消化道重建对GC患者的应用及患者Cyclin D1蛋白表达的影响.方法选取2015-05/2018-05天津市第五中心医院收治的行择期腹腔镜下全胃切除术的GC患者120例,随机分为两组,各组60例,研究组应用"P"形空肠袢空肠食管Roux-en-Y吻合术进行消化道重建,对照组应用空肠食管Roux-en-Y吻合术治疗.将两组患者手术时间、术中出血量、术后患者营养状况、并发症发生率以及CyclinD1蛋白表达情况进行对比.从而探究腹腔镜辅助消化道重建对GC患者的应用及其临床价值.结果两组患者术中出血量无差异(P>0.05),就手术时间、肠功能恢复时间方面,研究组低于对照组(P <0.05);研究组患者白蛋白、总蛋白、血红蛋白水平皆高于对照组(P<0.05);研究组上腹饱胀的发生率与倾倒综合征发生率较对照组(P<0.05),而腹泻、反流性食管炎、吻合口狭窄、吻合口出血以及肺部感染发生率两组间无明显差异(P>0.05);两组患者术后7 d,检测CyclinD1蛋白表达,所有患者皆为阴性,两组间无明显差异(P>0.05).结论全GC切除术后进行腹腔镜下消化道重建,有利于患者消化功能的恢复,提高患者术后营养水平,且不增加CyclinD1蛋白表达水平,临床上应当进一步推广应用.

Low-Density Parity-Check Codes: Research Status and Development Direction

In this paper, we conclude five kinds of methods for construction of the regular low-density parity matrix H and three kinds of methods for the construction of irregular low-density parity-check matrix H. Through the analysis of the code rate and parameters of these eight kinds of structures, we find that the construction of low-density parity-check matrix tends to be more flexible and the parameter variability is enhanced. We propose that the current development cost should be lower with the progress of electronic technology and we need research on more practical Low-Density Parity-Check Codes (LDPC). Combined with the application of the quantum distribution key, we urgently need to explore the research direction of relevant theories and technologies of LDPC codes in other fields of quantum information in the future.

中国尤小粪蝇属修订(双翅目:小粪蝇科)

修订了中国尤小粪蝇属Eulimosina的种类,记述1新种:刺尤小粪蝇Eulimosina squamospina sp.nov.,并提出1新组合:瘤微小粪蝇Minilimosina(Minilimosina)prominulata(Su,2013)comb.nov.,还提供了该属分种检索表。

东平湖水化学特征及成因分析

地表水化学参数特征及其成因分析是地表水资源评价与管理的重要组成部分。为研究泰安市东平湖水化学特征及成因,采用空间插值、Piper三线图、Gibbs图以及相关性分析等方法,探讨了研究区不同月份、不同类型东平湖地表水水化学组份特征及影响因素、各离子的来源等问题。结果显示,东平湖湖水属于碱性水体,TDS时空分布差异显著,10月份总体浓度最高,8月份最低;6月湖区TDS含量从湖区东南向西北逐渐递增,10月从湖心向南北两侧逐渐递增。研究区湖水主要水化学类型由SO_(4)-Na→SO_(4)-Na·Ca·Mg→SO_(4)-Ca型转变,该地区地表水的水化学类型易多变;水体中阳离子以Na^(+)为主,Ca^(2+)稍次之,阴离子以SO_(4)^(2−)为主;水体中K^(+)和Na^(+)来源于大气环流所携带的海盐,HCO−3和Mg^(2+)可能来自白云岩等碳酸盐岩或黑云母的风化溶解,SO_(4)^(2−)则主要来源于人类活动,少量来自石膏溶解,Ca^(2+)则来源于钙长石的风化以及石膏的溶解。由此可见,东平湖水体离子组分基本来源于蒸发结晶,部分组分来源于岩石风化,大气降水的输入作用十分微弱。

聚L-乳酸泡沫材料制备及油水分离应用

以聚L-乳酸(PLLA)/四氢呋喃为淬火溶液,通过热致相分离法得到PLLA泡沫材料。泡沫由直径为(45±13)μm的多孔微球组成。以PLLA泡沫材料为油水分离材料,研究其对十二醇、机油、石蜡油和硅油的吸附和油水分离性能。实验结果表明,PLLA泡沫材料的比表面积和孔隙率分别高达13.9m^2/g和97.5%,水接触角(WCA)为141.8°,与普通PLLA流延膜相比水接触角约增加了70°。PLLA泡沫材料对4种油的吸附容量均大于12g/g,为流延膜的14~19倍。吸油容量的增加主要与泡沫材料的高孔隙率和大比表面积,及材料表面和内部的微/纳结构有关。由于超疏水性、亲油性和毛细管效应,PLLA泡沫材料可以快速吸收漂浮在水面上的油层,可作为一种理想的油水分离材料。