Mesomorphism of Lanthanide(Ⅲ) 4-Hexyloxybenzoates

The 4-alkoxybenzoic acids are well-known liquid crystals showing several mesophases (nematic, smectic C phase or both) depending on the alkoxy chain length and whereby the rigid core of the mesogen is formed by intermolecular hydrogen bonds. In this paper it is shown that the thermal behaviour of lanthanide salts of 4-hexyloxybenzoic acids depends on the lanthanide ion (Ln=La, Pr, Nd, Sm, Eu). The lanthanum(Ⅲ) and praseodymium(Ⅲ) 4-hexyloxybenzoates exhibit a smectic A mesophase. No mesophase is found for the corresponding compounds of heavier lanthanides. The thermal properties of the lanthanide(Ⅲ) 4-hexyloxybenzoates were investigated by differential scanning calorimetry (DSC), polarising thermo-optical microscopy and synchrotron X-ray radiation.

Linac Beam Dynamics Code Benchmarking

The code benchmarking for hadron linac using the 3D Particle-In-Cell (PIC) code is an important task in the European framework “High Intensity Pulsed Proton Injector” (HIPPI). PARMILA and HALODYN are two of the codes involved in this work. Both of these codes have been developed and used for linac design and beam dynamics studies. In this paper, the simulation results of the beam dynamics were compared and analyzed. As predicted by two codes, the simulation results show some agreements. The physical design strategy which was adopted in two codes was also discussed.

Synthesis and X-Ray Diffraction Analyses of Calcium Hydroxide Nanoparticles in Aqueous Suspension

Calcium hydroxide nanoparticles in aqueous suspensions (also called nanolime) were successfully employed in Cultural Heritage conservation thanks to the ability of favoring readhesion of the pictorial layer on original carbonatic substrates or allowing to a better superficial cohesion and protection of treated stones. In this work, we have synthesized nanolime particles in aqueous suspension by two different methods. The produced particles were characterized in the laboratory, in terms of structural and morphological features, by means of X-Ray diffraction powder (XRD) and by transmission electron microscopy (TEM), respectively. Nanoparticles were crystalline, regularly shaped, hexagonally plated and with side dimensions generally ranging from 300 nm to 30 nm or less. Crystal structure of nanolime particles directly in the aqueous suspension, has been also analyzed by synchrotron diffraction from X-ray synchrotron radiation (SR-XRD);data have been analyzed by means of the Rietveld method and we have investigated the structure of Ca(OH)2 particles in suspension in terms of cell parameters, atomic coordinates, bond lengths and angles.

Structure of the myenteric plexus in normal and diseased human ileum analyzed by X-ray virtual histology slices

BACKGROUND The enteric nervous system(ENS)is situated along the entire gastrointestinal tract and is divided into myenteric and submucosal plexuses in the small and large intestines.The ENS consists of neurons,glial cells,and nerves assembled into ganglia,surrounded by telocytes,interstitial cells of Cajal,and connective tissue.Owing to the complex spatial organization of several interconnections with nerve fascicles,the ENS is difficult to examine in conventional histological sections of 3-5μm.AIM To examine human ileum full-thickness biopsies using X-ray phase-contrast nanotomography without prior staining to visualize the ENS.METHODS Six patients were diagnosed with gastrointestinal dysmotility and neuropathy based on routine clinical and histopathological examinations.As controls,fullthickness biopsies were collected from healthy resection ileal regions after hemicolectomy for right colon malignancy.From the paraffin blocks,4-μm thick sections were prepared and stained with hematoxylin and eosin for localization of the myenteric ganglia under a light microscope.A 1-mm punch biopsy(up to 1 cm in length)centered on the myenteric plexus was taken and placed into a Kapton®tube for mounting in the subsequent investigation.X-ray phase-contrast tomography was performed using two custom-designed laboratory setups with micrometer resolution for overview scanning.Subsequently,selected regions of interest were scanned at a synchrotron-based end-station,and high-resolution slices were reported.In total,more than 6000 virtual slices were analyzed from nine samples.RESULTS In the overview scans,the general architecture and quality of the samples were studied,and the myenteric plexus was localized.High-resolution scans revealed details,including the ganglia,interganglional nerve fascicles,and surrounding tissue.The ganglia were irregular in shape and contained neurons and glial cells.Spindle-shaped cells with very thin cellular projections could be observed on the surface of the ganglia,which appeared to build a network.In the patients,there were no alterations in the general architecture of the myenteric ganglia.Nevertheless,several pathological changes were observed,including vacuolar degeneration,autophagic activity,the appearance of sequestosomes,chromatolysis,and apoptosis.Furthermore,possible expulsion of pyknotic neurons and defects in the covering cellular network could be observed in serial slices.These changes partly corresponded to previous light microscopy findings.CONCLUSION The analysis of serial virtual slices could provide new information that cannot be obtained by classical light microscopy.The advantages,disadvantages,and future possibilities of this method are also discussed.

<i>In</i>-<i>Situ</i>XAFS Characterization of PtPd Nanoparticles Synthesized by Galvanic Replacement

Platinum-palladium nanoparticles are synthesized and characterized with regard to their application in fuel cells due to their high (electro) catalytic activity. Different preparation times are applied leading to different structures, from Pd cubic to core-shell PtPd concave, and different chemical compositions. The resulting particles are studied via Transmission Electron Microscopy (TEM) and in-situ X-ray absorption fine structure (XAFS) measurements. The latter allows the investigation of the oxygen reduction reaction following the variations with varying applied potentials by analysis using the Iterative Transformation Factor Analysis (ITFA) and the creation of a two-component system that consists of metallic Pt-Pd and the related oxide. With the used model, the different concentrations of the oxide are linked to the consecutive chemical steps of the oxygen reduction reaction. Finally, the catalytic activity of the particles is determined via linear scanning voltammetry and reveals a dependence on the shape and the composition of the particles.

Evolution and impact of cellulose architecture during enzymatic hydrolysis by fungal cellulases

The enzymatic hydrolysis of cellulose is still considered as a main limiting step of the biological production of biofuels from ligno-cellulosic biomass. Glycoside hydrolases from Trichoderma reesei are currently used to produce fermentable glucose units from degradation of cellulose packed in a complex assembly of cellulose microfibrils. The present work describes the structural evolution of two prototypical samples of cellulose (a micro-crystalline cellulose and a bleached sulfite pulp) over 5 length scale orders of magnitude. The results were obtained through wide angle, small angle and ultra-small angles synchrotron X-ray scattering, completed by Small Angle Neutron Scattering and particle size analyzers. These structural evolutions were followed as a function of enzymatic conversion. The results show that whereas there is no change at the nanometer scale, drastic changes occur at micron. The observed decrease of the size of the cellulose particles is accompanied by a smoothing of the crystalline surfaces that can be explained by a two-step mechanism of the enzymatic hydrolysis.

铝合金熔焊微气孔的三维同步辐射X射线成像

基于同步辐射X射线成像技术,对激光复合焊7020-T651铝合金接头内部的微气孔进行了研究,对气孔的体积、圆整度、扁平度及气孔形心至自由表面的距离等三维特征参数进行了统计分析与拟合.结果表明,铝合金熔焊微气孔主要为近球形的冶金型气孔,圆整度在0.65以上,以焊缝中心近似呈现对称分布,且焊缝上部气孔尺寸较大,热影响区和下部气孔密集且尺寸较小.等效直径在20 mm范围内的气孔,在接头上部和下部的频率分别高达65%和85%,并且100 mm以上的大尺寸气孔较少见.此外,由于熔池的下塌倾向和快速凝固,残留于枝晶网络间液相导致焊缝下部形成垂直于焊缝且层叠分布的形状复杂的热裂纹,少部分气孔之间以及气孔和热裂纹之间存在着连通现象,从而使得下部微气孔的圆整度平均值变小.此外,焊接速率越大,整个接头内部气孔体积分数越小,但对气孔形貌和位置的分布影响并不明显.

Design of molecule-based magnetic conductors

在工艺的设备启用讲道理地设计的薄电影的使用是在材料科学的一个公认的目标。然而，与控制得好的尺寸和生长方向用高度订的超分子的体系结构构造如此的薄电影留下了一逃犯目标。这里，我们介绍一个 layer-by-layer 协议种包括 arachidic 酸和施主二度(ethylenedioxy ) 的基于分子的磁性的售票员的混合薄电影 tetrathiafulvalene (BEDO-TTF ) 作为器官的部件和 Cu/Gd 建筑群作为无机的部件。分层的混合薄电影的构造被采用 Langmuir-Blodgett 方法以周围的条件完成，它在电影厚度上提供好控制并且在单层分子收拾行李。是由 X 光检查衍射示威了，这些电影与不同器官、无机的 sublattices 是水晶的，在 BEDO-TTF 分子的层与无机的层被连接的地方。由于 Langmuir-Blodgett 免职技术的灵活性，这结果与各种各样的功能向秩序井然的电影的准备显示一条线路，自愿与 BEDO-TFF 的单位被相结合的无机的混合物的决定了。而且，在许多底层上扔电影的能力在便宜底层上为降低费用的设备制造建立潜力。

4D imaging of void nucleation,growth,and coalescence from large and small inclusions in steel under tensile deformation

Samples of SA508 grade 3 nuclear pressure vessel ferritic steel were subjected to tensile straining whilst being simultaneously imaged in 3D in real time using high resolution,high frame rate time-lapse synchrotron computed tomography(CT).This enabled direct observation of void development from nucleation,through growth to coalescence and final failure validating many inferences made post-mortem or by theoretical models,as well as raising new points.The sparse,large inclusions were found to nucleate voids at essentially zero plastic strain(consistent with zero interfacial strength);these became increasingly elongated with straining.In contrast,a high density of small spherical voids were found to nucleate from the sub-micron cementite particles at larger strains(>200%)only in the centre of the necked(high triaxiality)region.An interfacial strength approaching 2100 MPa was inferred and soon after their nucleation,these small voids coalesce to form internal microcracks that lead to the final failure of the specimen.Perhaps surprisingly,under these conditions of generally low triaxial constraint the large voids are simply cut across and appear to play no significant role in determining the final failure.The implications of these results are discussed in terms of ductile fracture behaviour and the Gurson model for ductile fracture.

Vasarely painting at the nanoscale on sapphire crystals

We demonstrate that convenient thermal treatment of a specific sapphire vicinal surface can induce the formation of a fully two-dimensional(2D)ordered surface made of a periodic assembly of(006)facets.The simiarity between the resuting surface topography and pattemns represented in the hexagon series"of paintings by Vasarely is really striking!We thus propose to call these surfaces as"nanoscaled Vasarely surfaces".We also show that the self-organization process,which is driven by the minimization of the free energy of a closed system,results in a quasi-linear isothermal growth of the facets'surface area over time.