Nonisothermal Crystallization Behavior of Polypropylene Grafted Silane and Styrene Using γ-Ray Irradiation

Polypropylene grafted silane and styrene (named PP-g-Si/St in this article) was successfully prepared by radical graft polymerization initiated by γ-ray irradiation. The influence of total absorbed dose on the graft ratio of vinyltrimethoxysilane onto PP and the melt flow rate (MFR) of the PP-g-Si/St product were studied. The effect of graft ratios of vinyltrimethoxysilane on the melting point and nonisothermal crystallization kinetics of PP-g-Si/St was investigated by the method of differential scanning calorimetry (DSC). With increasing vinyltrimethoxysilane and styrene (used as viscosity modifier and free radical source) grafted on PP, the melting point of PP-g-Si/St became lower. Several different analysis methods, including those of Avrami, Jeziorny, and Mo and colleagues, were employed to describe the nonisothermal crystallization process of the grafted samples. The results indicate that the peak temperature of crystallization of PP-g-Si/St sample was lower than that of virgin PP. Crystallization kinetics revealed that the rates of nucleation and growth were affected differently by the graft ratio of vinyltrimethoxysilane onto PP. The activation energy was calculated on the basis of the method of Kissinger, and the values were 253.6 and 215.7 kJ/mol for virgin PP and PP-g-Si/St, respectively.     

Effect of the ratio of transition dipole moments on few-cycle pulse propagation

Propagation of a few-cycle laser pulses in a dense V-type three-level atomic medium is investigated based on full-wave Maxwell-Bloch equations by taking the near dipole-dipole (NDD) interaction into account. We find that the ratio, γ, of the transition dipole moments has strong influence on the time evolution and split of the pulse: when γ≤ 1, the NDD interaction delays propagation and split of the pulse, and this phenomenon is more obvious when the value of γ is smaller; when γ = 2, the NDD interaction accelerates propagation and split of the pulse.     

用多面体测试分度误差研究

采用多面体和光电平行光管测试圆刻机分度误差，比较了１２、３６、７２面体的测试特点，从数据分析中可找到一些造成误差的因素     

Automatic analysis of three-dimensional displacement field using ESPI

Electronic speckle pattern interferometry (ESPI) has been used to study the in-plane and out-of-plane displacements of the object. In order to improve the accuracy, a Fourier filtration algorithm has been used to remove the speckle noise and get the holographic-quality ESPI fringe pattern. The processing steps of this method are described in detail in this paper. In addition, a phase shifter, which is easily used with simplified structure and high stability, is also presented. It can be applied to various coherent arrangements in experiments to obtain phase shifted fringe patterns. Experiments of determining the 3D displacement field of a circular fixed plate with a uniform load have been carried out using these methods. The results presented in this paper indicate that the accuracy of this method is satisfactory.     

Ein LIFO Branch and Bound Verfahren zur optimalen Altstoffbehälterallokation

Zusammenfassung In diesem Artikel wird auf ein Problem eingegangen, das sich im Rahmen einer abfallwirtschaftlichen Studie ergab, in der die Durchführbarkeit von Altstoffsammlungen im dichtverbauten Siedlungsgebiet untersucht wurde. Als wichtige Teilaufgabe war dabei eine platzminimale Altstoffbehälterkombination für jede Altstoffart und für jedes Haus des untersuchten Sammelgebietes zu ermitteln, wobei unter anderem die Zugänglichkeit des Behälterraumes für die Sammelmannschaft und dessen topographische Gegebenheiten zu beachten waren. Zur Lösung dieser Aufgabe, deren Formalisierung auf ein ganzzahliges LP führte, wurde ein LIFO Branch and Bound Verfahren entwickelt. Dieses wird an Hand der wesentlichen Bestandteile eines jeden Algorithmus vom Branch and Bound Typ: der Branching Strategie, der Bounding Strategie und der Search Strategie dargestellt. Der Algorithmus wurde in PL/I programmiert und hat seine Leistungsfähigkeit in zahlreichen Programmläufen unter Beweis gestellt.

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Summary In this article a problem is treated which rose in the course of a research into the suitability for reconditioning used materials. This study analyzes the feasibility of scrap collection in densily populated, urban areas. One major aspect was to provide for a space saving combination of containers for every kind of scrap and for each house of the test area, bearing in mind the constraints given by the topographical conditions of the container room and its accessibility to the collection personnel. The formulation of this problem led to an all integer program. To solve this program a LIFO branch and bound algorithm was developed. The algorithm is presented by discussing its branching strategy, its bounding strategy and its search strategy, which constitute the essential parts of each procedure of the branch and bound type. The algorithm was programmed in PL/I and proved its efficiency in numerous runs.

     

Electroless gold deposition on silicon(100) wafer based on a seed layer of silver

This article describes a method of electroless gold deposition on a Si(100) wafer having a silver surface as seed layer. The seed layer was firstly deposited onto the surface of an etched wafer in an acidic solution of 0.005 mol/L AgNO₃+0.06 mol/LHF. The electroless gold deposition is performed by immersing the Ag-activated wafer in an electroless bath with a composition of 1.27×10^-3 mol/L[AuCl₄]^-+2.00×10^-2 mol/LNaH₂PO₂+8.32×10^-2 mol/L NH₂CH₂CH₂NH₂ (pH = 9.0–9.5). The bath temperature is 50–70 °C. The morphology of the seed layer and the gold film were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS).PACS 82.45.Mp; 81.15.Pq; 81.10.Dn     

Issues on nanoimprint lithography with a single-layer resist structure

We summarize our key developments in nanoimprint lithography (NIL) that employs a single layer resist lift-off process: lowering of the imprint temperature (for thermal imprint) and pressure, achieving uniform resist thickness and low residual resist layer thickness in the trenches, and eliminating metal ‘rabbit ears’ for the single-layer lift-off. In thermal NIL, our requirements for lower operating temperature and pressure motivated us to develop an alternative resist that is a viscous fluid at room temperature and cures at a lower temperature of 70 °C than the operating temperature of the conventional thermal NIL (≈200 °C). For UV NIL, we devised a method to dispense the resist onto a hydrophobic mold and use the hydrophilic substrate surface to spread the resist via surface wetting to engineer a continuous and uniform film. We also explored the use of Si(110) substrates as molds to produce features with perfectly vertical side walls, and the use of aqua regia to directly etch away rabbit ears. PACS 86.65.+h; 81.16.Nd; 81.16.Rf     

Skyrmions from instantons inside domain walls

Some years ago, Atiyah and Manton described a method to construct approximate Skyrmion solutions from Yang-Mills instantons. Here we present a dynamical realization of this construction using domain walls in a five-dimensional gauge theory. The non-Abelian gauge symmetry is broken in each vacuum but restored in the core of the domain wall, allowing instantons to nestle inside the wall. We show that the world volume dynamics of the wall is given by the Skyrme model, including the four-derivative term, and the instantons appear as domain wall Skyrmions.     

Pulsed laser deposition of high-quality ZnO films using a high temperature deposited ZnO buffer layer

High-quality ZnO film growth on sapphire was achieved by pulsed laser deposition using a high temperature deposited ZnO buffer layer. This high temperature deposited buffer layer remarkably improves crystallinity of subsequent films. In particular, the full width at half-maximum of X-ray diffraction ω-rocking curves for ZnO films grown with the buffer layer is 0.0076° (27.36 arcsec) and 0.1242° (447.12 arcsec) for the out-of-plane (002) and in-plane (102) reflections, respectively. In addition, ZnO films grown with this buffer layer showed a carrier mobility of 88 cm²/V s, which is three times higher than that realized for ZnO films grown without the buffer layer. The room temperature photoluminescence spectra showed strong band edge emission with little or no defect-related visible emission. PACS 78.55.Et; 81.05.Dz