甲烷在钯基催化剂上脱氢的分子模拟

为探明甲烷在钯基二聚体催化剂上脱氢反应过程的微观机理,对甲烷燃烧催化剂的设计与使用提供指导。在M06L/6-311++G(d,p)+SDD//M06L/6-311G(d,p)+LANL2DZ基组水平上,采用密度泛函理论(DFT)对甲烷在钯基二聚体催化剂(Pd_2、PdPt和PdNi)上的脱氢过程进行了研究。对比了甲烷在催化剂Pd_2、PdPt和PdNi上反应的能垒(E_b)、活化能(E_a)及反应速率常数(k),结果表明:CH_2→CH是甲烷在二聚体Pd_2反应的速率控制步骤(RDS),而CH_3→CH_2是催化剂PdPt和PdNi反应的RDS;钯基二聚体催化剂对甲烷脱氢的催化活性顺序为PdPtPd_2PdNi;抗积炭性能顺序为PdNiPd_2PdPt。PdPt适用于要求催化效率较高的项目,而抗积炭性能较好的PdNi催化剂可用于大型工业催化。     

面向技术问题的3D打印关键技术专利规避设计方法

在工程实践中,为了解决存在的技术问题,需要对现有产品进行创新设计,针对产品创新设计中普遍存在的专利规避需求,结合TRIZ建立了专利规避设计流程,包括规避问题的提出、规避对象的确定和规避设计;以FDM技术为例,对造成FDM技术成型精度低和打印速度慢的问题进行分析,并结合问题原因,专利检索到了在保证打印精度的前提下提高打印速度的技术方案,通过技术迁移,建立了迁移后的初始模型,并利用TRIZ中的功能裁剪进行了专利规避设计和侵权判定,可为企业及研究机构利用专利信息实施专利规避设计提供参考。     

中医学视角下城市物质空间的生命要素探析

通过借鉴中医学整体观和生命观的相关理论,从认识城市有机体的生命属性入手,发现并提炼能够产生和传递城市运营所需各种能量的生命要素:廊道和功能体。阐释了其多层级、多性质和多形态的特点,提出了功能体有动力、廊道成系统、敏感点有活力的疏通策略,旨在促进城市各种能量的有机循环,从而维护城市的健康与安全,提高城市生活的效率与质量。     

Theoretical study of the structural,elastic and thermodynamic properties of chalcopyrite ZnGeP2

The structural, elastic, and thermodynamic properties of ZnGeP₂ with chalcopyrite structure are investigated using the pseudo-potentials plane wave method based on the density functional theory with the generalized gradient approximation. The lattice parameters (a, c and u) are directly calculated and agree well with previous experimental and theoretical results. The obtained negative formation enthalpy shows that ZnGeP₂ crystal has strong structural stability. We have also calculated the bulk modulus B and the elastic parameters (C₁₁, C₁₂, C₁₃, C₃₃, C₄₄, and C₆₆) which have not been measured yet. The accuracy and reliability of the calculated elastic constants of ZnGeP₂ crystal are discussed. In addition, the pressure and temperature dependencies of the lattice parameters, bulk modulus, Debye temperature, Grüneisen parameter, entropy, volume thermal expansion coefficient, and specific heat capacity are obtained in the ranges of 0–20 GPa and 0–1200 K using the quasi-harmonic Debye model. To our knowledge this is the first quantitative theoretical prediction of the thermodynamic properties for ZnGeP₂ compound and still awaits experimental confirmations.     

A model- and simulation-based approach for tolerancing and verifying the functional capability of micro/nano-structured workpieces

The evaluation of functional features of manufactured workpieces is based on GO- and NO-GO-test results, which are obtained by comparing measured geometric characteristics with nominal dimensions and tolerances specified by the designer. These geometrical specifications are based on a tolerancing system, which was originally defined for the function mating capability. Against the background of upcoming lots of other new functions (like reduction of flow resistance, light absorption, reduction of friction, diffraction of light, self-cleaning or mass transmission) are to be realized with our products – particularly by micro- and nano scaled features. If the verification process will deliver the prediction of the achievable degree of functionality, the usability of a part can be assessed more accurately and in consequence quality and economics can be improved. So, a new principle for tolerancing and verifying turns out to be necessary. In this paper the fundamental deficit of the actual tolerancing and specification systems GPS and ASME Y14.5 is derived and the path for enlarging the system by preposing a functional model is shown. To verify the functional capability of the workpieces an approach based on simulations done with the parameterized mathematical–physical model of the function is suggested. Advantages of this approach will be discussed and demonstrated by examples with microstructured inking rolls, crankshafts and injection valves.     

Functional and conformational characterisation of walnut protein obtained through AOT reverse micelles

Walnut protein was extracted from defatted walnut flour by bis (2‐ethylhexyl) sodium sulfosuccinate (AOT) reverse micellar system and alkali solution with isoelectric precipitation. The functional and conformational characteristics of two proteins were investigated and compared. Walnut protein obtained through AOT reverse micelles was found to have higher extraction yield, solubility, emulsifying activity, foam capacities, water‐ and oil‐holding capacity compared to the protein from alkali solution along with isoelectric precipitation, while the surface hydrophobicity (H₀), contents of disulphide bond (SS) and sulfhydryl group (SH) were relatively lower. The differences of H₀, SS and SH contents could be due to the conformational changes of walnut proteins using two extraction methods. FTIR spectra and data showed that the reverse micelles caused the decrease in α‐helix, β‐sheet, random and β‐turn of walnut protein, the increase in the side‐chain structure content, which could be responsible for the modification of functional properties.     

Density functional theory study on dehydrogenation of methylcyclohexane on Ni–Pt(111)

Methylcyclohexane is a very promising liquid organic hydrogen carrier, but its dehydrogenation mechanism on Pt-based bimetallic catalysts is not yet clear. In order to understand the catalytic dehydrogenation of methylcyclohexane on Ni–Pt(111), DFT calculations were performed and the calculation results were compared with the corresponding values on Pt(111). It is shown that because the electronegativity of Ni atoms is less than that of Pt atoms, electrons transfer from Ni atoms to Pt atoms. Compared with Pt(111), the binding energy (the absolute value of the adsorption energy) of related species on Ni–Pt(111) surface was smaller, indicating that the binding strength between these species and the surface metal atoms on Ni–Pt(111) is weaker. In the stable adsorption configurations on Ni–Pt(111), almost all the metal atoms forming chemical bonds with the adsorbates were Pt atoms, indicating that Pt was the main active component. Although the actual catalytic reaction is more complicated, this study provided some insights into one of the important aspects.     

软件功能安全验证活动的应用

软件功能安全验证活动对提高安全关键系统的安全性具有重要作用,它贯穿于软件安全生命周期的各个阶段。通过对各阶段输出文档的审查和分析,可尽早发现软件问题,降低软件修复成本。完整的问题闭环处理流程可有效解决软件验证活动中发现的问题,给出各方均满意的处理结果。     

Characterisation,storage viabilit,and application of microspheres with Lactobacillus paracasei obtained by the extrusion technique

The objective of this study was to evaluate the influence of pH, bile salts and different storage conditions at two different temperatures (30 and 4 °C) on the viability of free and microencapsulated Lactobacillus paracasei. Microspheres encapsulating L. paracasei were obtained using an extrusion method. The efficiency was 87.6%, the diameter 70 µm and the zeta potential 7.22 ± 0.05 mV. Encapsulated L. paracasei showed higher resistance to stomach pH and bile salts compared to free cells. Microspheres were evaluated under four different storage conditions: fresh, suspended in a solution with a pH of 4, suspended in saline solution and lyophilised. The lyophilised microspheres presented the highest stability with 89.2% survival rate after six weeks of storage; however, free bacteria in saline solution (0.145 N) presented a 65.3% survival rate. Finally, a new product (a strawberry ice popsicle) with possible functional characteristics was obtained using microencapsulated L. paracasei.