Characterization of selected paper documents from the archives of Palazzo Ducale (Venice), Italy using various analytical techniques

The paper manufacturing process remained unchanged for many centuries, until, in the nineteenth century, the crisis of rags led industrialized countries to patent new production processes with different raw materials. This study deals with this period of transition by analyzing four samples stored at the archives of Superintendency Beni Architettonici per il Paesaggio e per il Patrimonio Storico Artistico ed Etnoantropologico (BAPPDAD) of Venice Lagoon, based in the Palazzo Ducale.The samples were analyzed by FT-IR (ATR), SEM-EDS, HPLC-MS/MS and Py-GC/MS. These techniques allow the characterization of various raw materials and adhesives used in various stages of paper production.These analyses have found a gradual introduction of ground wood in the composition of papers from the mid-nineteenth century, and the use of rosin as glue only in more recent documents.     

一种考虑剪切变形的平行四边形厚/薄板通用单元

根据Timoshenko二广义位移梁理论，构造了深梁位移场的插值函数。利用斜坐标系与直角坐标系的变换关系、有限条带思想和深梁位移插值函数，构造了一种考虑剪切变形的平行四边形厚／薄板弯曲通用单元的位移(曲率、剪应变、转角、横向位移)插值函数，导出了刚度矩阵和非结点荷载等效力。并对简支阍支方板、Razzaque斜板、四边简支斜交板弯曲进行了数值计算。算例表明此单元有较好的精度，对于薄板不出现剪切闭锁，可适应于目前桥梁建设中大量采用的斜交板桥结构分析。     

Ballistic and numerical simulation of impacting goods on conveyor belt rubber

Impact loading is an important process in the transport industry as it causes wear and failure of critical components. Conveyor belts are of particular importance as they are used in practically every industry where large quantities of goods are moved over short (<10 m) or long distances (>1 km). To investigate stress levels inside the material during impact loading, a gas gun was utilized to shoot 9 mm spherical steel balls onto the surface of a rubber conveyor belt. A high speed video recording system was employed in order to determine penetration depth and dissipated energy of the steel ball. Maximal penetration depths of up to 3.9 mm and maximal dissipated energies of up to 86.8 % were measured. Additionally, a numerical simulation using smooth particle applied mechanics was conducted and compared to the experimental results obtained with the gas gun. The calculated von Mises stresses affected the conveyor belts up to a maximum depth of 8.8 mm with at least 20 MPa. Maximum von Mises stresses were calculated to reach 60 MPa.     

纸质包装材料中甲醛、乙醛向食品模拟物改性聚苯醚的迁移行为

为了解纸质包装材料中甲醛、乙醛向食品模拟物改性聚苯醚( Tenax)中的迁移行为,建立了一步提取衍生化、超高效液相色谱测定纸质包装材料和Tenax中的甲醛和乙醛的方法。本方法在甲醛和乙醛的测定范围内,线性相关系数R2>0.9999,甲醛检出限为0.03 mg/m2,乙醛检出限为0.04 mg/m2,测定纸样和Tenax的加标回收率为90.1%~108.6%。采用本方法研究不同温度和时间下两种纸质包装材料中甲醛、乙醛向Tenax中的迁移规律。研究表明,甲醛、乙醛迁移行为随时间变化趋势大致相同,均呈现迁移率随迁移时间延长先迅速增大,后又减小达到一个常数;甲醛和乙醛迁移率受温度的影响不同,达到平衡后,甲醛在30℃下迁移率最高,乙醛在70℃和50℃下迁移率高;甲醛和乙醛向Tenax中的迁移率差异较大,达到平衡后,乙醛的迁移率远高于甲醛。     

Dynamic behaviour of an axially moving plate undergoing small cylindrical deformation submerged in axially flowing ideal fluid

The out-of-plane dynamic response of a moving plate, travelling between two rollers at a constant velocity, is studied, taking into account the mutual interaction between the vibrating plate and the surrounding, axially flowing ideal fluid. Transverse displacement of the plate (assumed cylindrical) is described by an integro-differential equation that includes a local inertia term, Coriolis and centrifugal forces, the aerodynamic reaction of the external medium, the vertical projection of membrane tension, the bending resistance, and external perturbation forces. In the two-dimensional model thus set up, the aerodynamic reaction is found analytically as a functional of the cylindrical displacement, using the techniques of complex analysis. The resulting integro-differential problem is discretized in space with the Fourier-Galerkin method, and integrated in time with the diagonalization method. Examples are computed with physical parameters corresponding to air and some paper materials. The effects of the surrounding fluid on the critical velocity and first natural frequency are investigated, for stationary air, for an air mass moving with the plate, and for some arbitrary axial fluid velocities. The obtained results are applicable for both an ideal membrane and a plate with nonzero bending rigidity.     

Recombinant cellulose crosslinking protein: a novel paper-modification biomaterial

Cellulose-binding domains have been isolated from various cellulases, and proteins, which lack hydrolytic activity. The hypothesis that a cellulose-binding domain can be used to alter surface and mechanical properties of paper was tested. Two cellulose-binding domains from Clostriium cellulovorans were fused to form a cellulose crosslinking protein (CCP). The recombinant bifunctional cellulose-binding protein was expressed in E. coli, appliedby immersion onto Whatman cellulose filter paper, and its mechanical properties were tested. The purified protein improved the treated paper's mechanical properties (tensile strength, brittleness, Young's modulus and energy to break). In addition, cellulose crosslinking protein treatment was shown to transform filter paper into a more water-repellent paper. The binding of cellulose-binding domains to cellulose under a wide range of envi-ronmentalconditions, without the need for chemical reactions, and its biodegradability make them attractive moieties for the design of a new class of paper-modification materials.p>     

用半波带法讨论单缝夫琅和费衍射的课件演示与制作

根据半波带法的思路，介绍了利用计算机课件演示对单缝夫琅和费衍射的条纹光强与衍射角之间的关系，以便有效地化解教学难点，帮助学生对该知识点形成清晰的认识和深化理解，同时对课件制作要点作了简要说明。     

Dynamics of coupled systems

A survey in the form of a review of the author’s research results in the area of dynamics of coupled rotations and coupled systems is presented. The theorem on the existence of a trigger of the coupled singularities and the separatrix in the form of the number eight is presented with a few examples of coupled rotations of the simple systems with debalances. Also, a survey of models and dynamics of coupled systems composed of a number of deformable bodies (plates, beams or belts) with different properties of materials and discrete layer properties is presented and mathematically described. The constitutive stress–strain relations for materials of the coupled sandwich structure elements are presented for different properties: elastic, viscoelastic and creeping. The characteristic modes of the coupled system vibrations are obtained and analyzed for different kinds of materials and structure composition. The visualization of the characteristic numbers and modes and eigenamplitude forms are presented. Structural analysis of sandwich structure vibrations is done.     

Analytical methods to determine cocaine contamination of banknotes from around the world

The presence of cocaine in a significant number of UK pounds (Xxxx), Euros (€) and North American banknotes ($) in general circulation requires appropriate tools to do determinations. This article discusses the-state-of-the-art in the analysis of cocaine on banknotes. We summarize the usual extraction methods of currency samples and compare them, especially with respect to avoiding sample damage. We critically discuss analytical methods, namely gas chromatography (GC) and liquid chromatography (LC), capillary electrophoresis (CE), immunoassay, thermal desorption tandem mass spectrometry (TD-MS²) and ion-mobility spectrometry (IMS). We also review cocaine levels on banknotes around the world and their possible relationship with drug consumption.     

Thermodynamic characteristics of the activity of selected chromatographic sorbents

Summary The possibility of comparing various chromatographic sorbents in respect of their activity is discussed utilizing a simple thermodynamic approach presented earlier.