Shape-dependent natural boundary condition of Lagrangian field

In the framework of the Lagrangian field theory, we derive the equations characterizing shape-dependent natural boundary conditions from the Hamilton’s principle. Of these equations, one exhibits mathematical pattern similar to general relativity. In this equation, one side of the sign of equality is the energy–momentum tensor of field and another side is the combination of mean curvature and Gaussian curvature of boundary surface. Meanwhile, we verify that the shape-dependent natural boundary condition can be simplified into the shape equation of lipid vesicle or the generalized Young–Laplace’s equation under different condition.     

Angular-based spatially resolved laser-induced breakdown spectroscopy: a new technique for the effective enhancement of signals without an external time delay system

In this study, we developed a novel angularbased spatially resolved laser-induced breakdown spectroscopy(ABSR-LIBS) technique. This new method allows the spatially resolved spectroscopic properties of laserinduced plasma to be investigated using different angles and polar distances with a spatially adjustable fiber optics probe. The experimental evaluations suggested that the intensity of the Al signal distributions in the ‘‘side-view'depended greatly on the angle of the collection probe. The location of a collection probe at 50° would facilitate efficient spectral collection and minimize the disturbance of the plasma plume. The spectral signals in the plasma emissions had different distribution at various polar distances using the same collection angle, and the highest signal intensity was observed between 15 and 35 mm polar distances. This ABSR-LIBS technique improved both the LIBS signal and the maximum emission intensity of Al atoms by several times at the best spatial position in our experimental conditions. Furthermore, we successfully obtained well-resolved line emission spectroscopy signals without any external time delay using a nongated spectrometer based on the ABSR-LIBS system. We consider that the ABSR-LIBS technique has great potential for obtaining new insights with laser-induced plasma instruments and it could facilitate the development of a low-cost instrument.     

Increase of characteristic X-ray production in a channelling direction

Abstract

Radiation in the Atmosphere. K. Ya. Kondratyev. Academic Press, 9 12 pages. $39.00

PrincipIes of Radiation Protection—A Textbook of Health Physics. Editors: K. Z. Morgan &; J. E. Turner Wiley, New York, 1967, 622 pages. dollar;13.95     

Detection of multiple elements in coal samples from Bangladesh by laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) was used to analyze the coal samples from the Barapukuria coal mine of Bangladesh and coal from eastern India. Besides the major elements carbon and silicon, a number of minor and trace elements, such as iron, titanium, aluminum, calcium, sodium, copper, zirconium, neodymium, ytterbium, cerium, samarium, dysprosium and gadolinium were identified. In earlier work some researchers identified the lines around 279 and 280 nm as due to Mg II rather than Yb III. The reasons for identifying these two lines as due to ytterbium in the present work are explained. The detection of multiple elements in one experiment in a commonly used fuel demonstrated the versatility and multi-elemental capability of LIBS.     

Bipolar model for electrical breakdown in polyethylene materials under dc high electrical fields

In this paper, we have applied our bipolar transport model for studying the charge dynamics in the insulating polyethylene materials, from nano to micro -scales and under dc high applied field. We have also applied the model for studying the electrical breakdown phenomenon for these mentioned scales. The principal results are dedicated to the evolution of the external current in low density polyethylene samples. Under notable dc high applied field, the electrical pre-breakdown phenomenon is indicated by an abrupt increase that occurs during the steady state of the external current.     

三区域膜泡相分离模式之间转变的研究

基于Helfrich弹性曲率模型，结合实验参数，用直接极小化方法对三区域膜泡的两种相分离模式的稳定形状，及其之间的相变进行了计算，得出相变点为φ_o^*=0.49，与实验结果φ_o^*=0.5很接近.用直接极小化方法还研究了三区域膜泡发生发芽的必要条件，指出只有当约化线张力系数足够大，并且膜泡内外溶剂能自由渗透时，才可能发生发芽形变，并对渗透的可能机制进行了探讨.     

Laser-induced breakdown spectroscopy in archeological science: a review of its application and future perspectives

Laser-induced breakdown spectroscopy (LIBS) in the last decades has become a promising analytical technique for a broad variety of archeological objects with great results obtained either alone or in combination with complementary techniques. It is mainly advantageous due to no sample preparation, minimally destructive, rapid analysis and depth profiling analysis spur LIBS technique to become a significant attractive technique for the characterization and conservation of archeological samples or artworks. The present paper describes in brief the basic principles and instrumentation of LIBS, and reviews several case studies on metallic alloys, ceramic, glass, painted artworks, historical buildings and biomaterials in the most recent 7 years (2011–2017) that demonstrate the applicability and prospects of LIBS in the field of archeological science.     

Triple hydrogen‐bonding block copolymers via RAFT polymerization: Synthesis,vesicle formation,and molecule‐recognition behavior

Reversible addition fragmentation chain transfer polymerization afforded triple hydrogen‐bonding block copolymers (PBA‐b‐PDAD) with well‐controlled molecular weight and molecular weight distributions (1.2–1.4). The complexation via specific hydrogen bonding between these block copolymers in CHCl₃ provided an unprecedented approach for the formation of spherical vesicles. Atomic force microscopy and dynamic light‐scattering measurements revealed that the resultant polymeric vesicles were about 100 nm in radius. Triple hydrogen‐bonding interactions between maleimide and PBA‐b‐PDAD resulted in the dissociation of these spherical vesicles, facilitating the guest molecule recognition. The hydrogen‐bonding interaction between maleimide and the PBA‐b‐PDAD was further confirmed by ¹H NMR and FTIR spectra. These results indicated that these vesicles of triple hydrogen‐bonding block copolymer could be a potential new vehicle for molecular recognition. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1633–1638     

A study of stalagmite samples from Baradla Cave (Hungary) by laser induced plasma spectrometry with automatic signal correction

In the present work, we studied the applicability of laser induced plasma/breakdown spectrometry (LIPS/LIBS) to speleothem analysis. Problems related to the use of time- and spatially integrating compact LIBS instrumentation, speleothem sample preparation, spectral line assignation and signal intensity correction have been addressed. A novel signal correction scheme, based on the total integrated spectral background, was developed and employed for the qualitative study of the lateral distribution profiles of major (Ca, Mg, C, O) and minor (Al, Si, Fe, Mn) elements detected in horizontally cut slices of stalagmite samples from Baradla Cave (Aggtelek, Hungary). Several new computer program modules were also developed to aid the spectral data evaluation. Correlations and trends found in the lateral distribution profiles were discussed, and based on their relations, tentative suggestions for the chemical compounds present in the samples were made.     

一种基于WBS的嵌入式软件估算方法

为确保嵌入式软件项目能够按照预定成本、进度顺利完成,提出一种基于WBS的嵌入式软件估算方法,并结合具体实例对规模/工作量估算、成本估算、进度估算、关键计算机资源估算和风险估算的内容进行了细致的描述.利用基于WBS的嵌入式软件估算方法进行估算,该结果与以往相类似软件实际结果比较,各项数值的误差均在±10%以内.该方法为有...