凝固科学技术与材料

从凝固科学与实践发展的角度介绍了当前凝固材料体系的基本框架和凝固科学主要发展阶段的基本理论。作为材料科学与工程的基本组成，凝固科学技术正在现代科学理论的基础上针对传统材料的改性提高和新材料的发展需求，以控形、控构、控性为目标开展优质铸件的定向、晶体生长、快凝、深过冷及各种新型和超常领域凝固过程的研究，并介绍了其中某些方面和展望了可能的发展趋势。     

The shape and stability of wall-bound and wall-edge-bound drops and bubbles

The behavior of wall-bound drops and bubbles is fundamental to many natural and industrial processes. Key characteristics of such capillary systems include interface shape and stability for a variety of gravity levels and orientations. Significant solutions are in hand for axisymmetric pendent drops for a variety of uniform boundary conditions along the contact line with gravity acting normal to a planar wall. The special case of a wall-bound drop or bubble that is also pinned at an edge (i.e. a ‘wall-edge-bound’ drop) is considered here where numerical solutions are obtained for interface shape and stability as functions of drop volume, contact angle, fluid properties, and uniform gravity vector. For a semi-infinite zero-thickness planar wall (plate), a critical contact angle is identified below which wall-edge-bound drops are always stable. The critical contact angle is computed as a function of the gravity vector. The numerical procedure, which makes no account for contact angle hysteresis, predicts that such wall-edge-bound drops are unconditionally unstable for any gravity field with a component that is tangent to the wall while inwardly normal to the edge. Select experiments are conducted that support the conclusions drawn from the numerical results.     

Synthesis and luminescent properties of alkali-metal and ammonium fluorosulfatozirconates and fluorosulfatohafnates

We have synthesized a variety of alkali-metal and ammonium fluorosulfatometallates (titanates, zirconates, and hafnates). The alkali fluorosulfatozirconates and fluorosulfatohafnates have been shown to exhibit efficient roentgenoluminescence (RL) in the UV through visible spectral region, with a maximum at 390–440 nm. Their RL spectra depend significantly on their composition (cation, anion, and water content), coordination of KF and K₂SO₄, and relative amounts of fluorine and SO₄ groups. We have examined the effect of heat treatment on the RL of these compounds. The rubidium and cesium fluorosulfatozirconates Rb₃Zr₂F₉SO₄ · 2H₂O, Cs₂ZrF₂(SO₄)₂ · 2H₂O, Cs₈Zr₄F₂(SO₄)₁₁ · 16H₂O, and Cs₂ZrF₄SO₄ offer the most efficient RL.     

Heat and Mass Transfer and Modeling and Prediction of Environmental Catastrophes

Basic definitions and concepts of the physicomathematical theory of natural catastrophes are given. Possibilities of mathematical modeling of natural and technogenic catastrophes are discussed in the context of the theory of heat and mass transfer and the mechanics of reacting media. The importance of taking into account conjugate heat and mass exchange in modeling catastrophes is emphasized. A formula for evaluating the probability of a collisional catastrophe is given.     

CellML and associated tools and techniques

We have, in the last few years, witnessed the development and availability of an ever increasing number of computer models that describe complex biological structures and processes. The multi-scale and multi-physics nature of these models makes their development particularly challenging, not only from a biological or biophysical viewpoint but also from a mathematical and computational perspective. In addition, the issue of sharing and reusing such models has proved to be particularly problematic, with the published models often lacking information that is required to accurately reproduce the published results. The International Union of Physiological Sciences Physiome Project was launched in 1997 with the aim of tackling the aforementioned issues by providing a framework for the modelling of the human body. As part of this initiative, the specifications of the CellML mark-up language were released in 2001. Now, more than 7 years later, the time has come to assess the situation, in particular with regard to the tools and techniques that are now available to the modelling community. Thus, after introducing CellML, we review and discuss existing editors, validators, online repository, code generators and simulation environments, as well as the CellML Application Program Interface. We also address possible future directions including the need for additional mark-up languages.     

Multi-ferroic and magnetoelectric materials and interfaces

The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions.     

Development and challenges of planning and scheduling for petroleum and petrochemical production

Production planning and scheduling are becoming the core of production management, which support the decision of a petrochemical company. The optimization of production planning and scheduling is attempted by every refinery because it gains additional profit and stabilizes the daily production. The optimization problem considered in industry and academic research is of different levels of realism and complexity, thus increasing the gap. Operation research with mathematical programming is a conventional approach used to address the planning and scheduling problem. Additionally, modeling the processes, objectives, and constraints and developing the optimization algorithms are significant for industry and research. This paper introduces the perspective of production planning and scheduling from the development viewpoint.     

Preparation,properties and chemistry of glass- and glass-ceramic-to-metal seals and coatings

An overview is given outlining the materials and technologies that have been employed in the preparation of glass- and glass-ceramic-to-metal seals and coatings. Metal/non-metal bonding theories are summarized, and the conditions required for the formation of strong chemical bonding are described and discussed. Particular reference is given to the interfacial chemistry involved for individual glass/metal and glass-ceramic/metal combinations. The major factors responsible for the preparation of high-quality seals and coatings, free from porosity and other undesirable defects, are also outlined and discussed. In addition, a number of applications for seals and coatings are briefly described.     

江澳两地高校文创设计的协同研究与商业实践

目的 探索江门世遗文化的传承、发展和转化的新思路,践行国家在《粤港澳大湾区发展规划》纲要中要求江门承担与港澳地区文化创意合作与开发任务的分工。方法 与澳门高校紧密合作,开展专业培训课程,以开平碉楼为例,从人文视角开展设计研究,梳理开平碉楼的文化脉络,把世遗文化的元素和其背后的文化融入文创产品中,提升文创产品的附加值,推动当地文创产业结构的变革。结果 两地高校构建了稳定的科研团队,开设长期有效的设计培训课程,与景区建立了研究协作关系,帮助景区构建了一套产销研的商业模式。结论 以跨区域高校合作为平台,以文创产品为抓手,依托江澳两地的资源优势,可以构建江门世遗文化全新的品牌形象,最终推动开平世遗文化的活化。     

Electronic and magnetic properties and structural stability of BeO sheet and nanoribbons

The novel electronic and magnetic properties of BeO nanoribbons (BeO NRs) as well as their stability are investigated through extensive density functional theory calculations. Different from semiconducting graphene nanoribbons and insulating BN ribbons, all zigzag edged BeO NRs are revealed to display ferromagnetic and metallic natures independent of the ribbon width and edge passivation. The polarized electron spins in H-passivated zigzag BeO NRs are from the unpaired electrons around the weakly formed Be-H bonds, while those of bare zigzag BeO NRs are due to the 2p states of edge O atoms. In sharp contrast, all armchair BeO NRs are nonmagnetic insulators regardless of the edge passivation. In particular, all bare armchair BeO NRs have a nearly constant band gap due to a peculiar edge localization effect. Interestingly, the band gaps of all armchair BeO NRs can be markedly reduced by an applied transverse electric field and even completely closed at a critical field. The critical electric field required for gap closing decreases with increasing ribbon width, thus the results have practical importance. Further stability analysis shows that bare BeO NRs are more stable than H-passivated BeO NRs of similar ribbon widths and bare armchair BeO NRs are energetically the most favorable among all the nanoribbons.     

Male and female electronics engineers and electronic engineering:attitudes and influences

This study reports on attitudes, backgrounds and perceived sources of influence of applicant and professional engineers with reference to electronic engineering. In general, both groups held positive attitudes and regarded electronic engineering as a varied, stimulating, creative and intellectually challenging profession. The study also investigated the backgrounds of engineers and revealed significant gender differences. Women engineers were more likely to have attended a single sex school and to report a family structure which contained another engineer. In addition, perceived sources of influence on the decision to become an engineer were different for men and women. These results are discussed in terms of some of their potential implications for recruitment into electronic engineering     

Interleukin-6 and C-Reactive Protein Production and Interaction in CRF and Dialysis

Some authors suggest that inflammation can be one of the reasons of erythropoietin (EPO) resistance. The purpose of the study was to follow-up some laboratory markers of inflammation in 21 dialysis patients, all treated with adequate anaemia doses EPO, divided in 2 groups: first one adequately responding to EPO treatment (with Hb higher than 9 g/L) and second one resistant to it (with Hb lower than 9 g/L). Some acute phase proteins and markers of inflammation were measured as follow: C-reactive protein (CRP), α1-AGT, α1-antitrypsine, and haptoglobine (HP), as some anti-acute phase proteins, transferrin (TF). WBC count, some enzymes: ASAT, ALAT, and substrates: urea, creatinine, albumins (Albs), lipid profile, glucose, phosphate, iron, electrolytes, and parathyroid hormone were tested as well. The study found significant higher CRP, HP, Tg, P, and Alb in the second group than in the first. TF was lower in all patients, which may be connected to the chronic inflammatory status (uremia), and there was no iron deficit or severe parathyroid hyperfunction to be convinced for EPO resistance. The study suggests that EPO resistance may be related to some inflammatory factors and treatment of the inflammation possibly will overcome the problem.     

Ferromagnetism and ferromagnetic resonance in Mn and As co-implanted Si and GaAs

Ferromagnetism persisting above 375 K and anisotropic ferromagnetic resonance (FMR) spectra have been detected for the first time in Si co-implanted with Mn and As and annealed under appropriate conditions. For comparison, semi-insulating GaAs samples have been implanted with the same ions and subsequently annealed. They also exhibit ferromagnetism with a Curie temperature well in excess of 375 K. High-resolution transmission electron microscopy (HR TEM) performed on the samples with the best magnetic characteristics has shown the presence of nanoclusters due to the segregation of the implanted species in both Si and GaAs. The angular dependence of the FMR spectra reveals the existence of magnetic entities with the hard magnetization axes aligned along the four equivalent 〈1 1 1〉 crystal axes. The spectra are very similar in Si and GaAs, indicating that hexagonal MnAs clusters might be formed in Si.     

语境与语义判断和选择

文章从翻译过程中语义的判断和选择行为入手，探讨语境的定义和种类，通过分类举例着重说明语境对语义的制约，并以此证明语境作为语义判断和选择的依据，是具体的、可操作的范畴。     

Synthesis and systematic investigations of Al and Cu-doped ZnO nanoparticles and its structural,optical and photo-catalytic properties

Here we report, copper (Cu) and Aluminum (Al) doped zinc oxide (ZnO) nanoparticles by a novel one step microwave irradiation method for the first time. Powder X-ray diffraction (XRD) reveals that both pure and doped samples assigned to hexagonal wurtzite type structure. The calculated average crystalline size decreases from 24 to 11 nm for pure and doped (Al and Cu) ZnO respectively, which is in good agreement with the particles size observed from Transmission Electron Microscope (TEM) analyses. A considerable red shift in the absorption edge and the reduction in the energy gap from 3.35 to 2.95 eV reveal the substitution of Al³⁺ and Cu²⁺ ions into the ZnO lattice analyzed by UV–Vis transmission spectra. The photocatalytic degradation of Methyl Violet (MV), Phenol and Rhodamine B (RHB) was investigated by using pure, Al and Cu doped ZnO catalyst under UV light irradiation. The results showed that the photocatalytic property is significantly improved by Cu doping concentration. This could be attributed to extended visible light absorption, inhibition of the electronehole pair’s recombination and enhanced adsorptivity of dye molecule on the surface of Cu–ZnO nanopowders. The samples were further characterized by photoluminescence spectra and Fourier Infrared Spectra (FTIR) analysis.     

Morphology and lattice distortions of nitrided iron and iron-chromium alloys and steels

Specimens prepared from iron, iron-chromium alloys (0 to 4 wt% Cr) and commercial steels (C45, 41Cr4, 15CrNi6 and 24CrMo13) were powder nitrided at 818 K for 0.25 to 32 h. After cooling to room temperature the resulting morphology, lattice distortions and compositional variations were determined by X-ray diffraction analysis, metallographic methods and electron microprobe analysis. In the diffusion zone of iron and iron-chromium (0.54 wt% Cr), -(Fe₁₆N₂)- and -(Fe₄N)-nitrides were observed, whereas specimens of the iron-chromium alloys with a higher chromium content showed a finely dispersed submicroscopical precipitation of CrN in the matrix and precipitates of Cr₂N at the grain boundaries. With increasing nitriding times for the iron-chromium alloy with the highest chromium content (3.82 wt% Cr) a discontinuous precipitation starting from the grain boundaries occurred. For the first time recrystallization phenomena in the diffusion zone were observed, indicating that the inward diffusion of nitrogen introduces large lattice distortions. Large distortions were determined from X-ray diffraction line shift and line broadening respectively. The behaviour of macro- and micro-strain as a function of nitriding time was interpreted in terms of the volume changes caused by nitriding and subsequent precipitation. The residual surface stresses were calculated from the macrostrains applying the Voigt-Reuss-mean model. The experimentally determined ratio of the macrostrains in the (100) and the (110) directions was in good agreement with the value predicted from the model. The corresponding ratio of the microstrains was significantly larger than this theoretical prediction, which can be attributed to precipitates growing along (100) planes in the matrix (such as -nitride and CrN). In contrast with the macrostrain, a strong relation was found between the microstrain and the chromium content of the specimen.     

Error and uncertainty in modeling and simulation

This article develops a general framework for identifying error and uncertainty in computational simulations that deal with the numerical solution of a set of partial differential equations (PDEs). A comprehensive, new view of the general phases of modeling and simulation is proposed, consisting of the following phases: conceptual modeling of the physical system, mathematical modeling of the conceptual model, discretization and algorithm selection for the mathematical model, computer programming of the discrete model, numerical solution of the computer program model, and representation of the numerical solution. Our view incorporates the modeling and simulation phases that are recognized in the systems engineering and operations research communities, but it adds phases that are specific to the numerical solution of PDEs. In each of these phases, general sources of uncertainty, both aleatory and epistemic, and error are identified. Our general framework is applicable to any numerical discretization procedure for solving ODEs or PDEs. To demonstrate this framework, we describe a system-level example: the flight of an unguided, rocket-boosted, aircraft-launched missile. This example is discussed in detail at each of the six phases of modeling and simulation. Two alternative models of the flight dynamics are considered, along with aleatory uncertainty of the initial mass of the missile and epistemic uncertainty in the thrust of the rocket motor. We also investigate the interaction of modeling uncertainties and numerical integration error in the solution of the ordinary differential equations for the flight dynamics.     

Cymbal and BB underwater transducers and arrays

The cymbal is a miniaturized class V flextensional transducer that was developed for use as a shallow water sound projector and receiver. Single elements are characterized by high Q, low efficiency, and medium power output capability. Its low cost and thin profile allow the transducer to be assembled into large flexible arrays. Efforts were made to model both single elements and arrays using the ATILA code and the integral equation formulation (EQI). Millimeter size microprobe hydrophones (BBs) have been designed and fabricated from miniature piezoelectric hollow ceramic spheres for underwater applications such as mapping acoustic fields of projectors, and flow noise sensors for complex underwater structures. Green spheres are prepared from soft lead zirconate titanate powders using a coaxial nozzle slurry process. A compact hydrophone with a radially-poled sphere is investigated using inside and outside electrodes. Characterization of these hydrophones is done through measurement of hydrostatic piezoelectric charge coefficients, free field voltage sensitivities and directivity beam patterns. Electronic Publication     

Photostability and toxicity of pentachlorophenol and phenanthrene

Fate of organic contaminants under UV irradiation as environmental variable was studied. Aqueous solutions of pentachlorophenol and phenanthrene were subjected to simulated solar radiation and monitored during ≤ 93 h. Immobilization tests were conducted using Daphnia magna neonates in pre-irradiated water for the assessment of photoproduct-mediated toxicity. We observed a time-dependent decrease in exposure concentrations following irradiation, which correlated positively with reduced immobilization of the animals. A complete disappearance of the lowest and highest concentrations of pentachlorophenol was noted after 25 h and 75 h, respectively. Survivorship of the animals increased until 100% and correlated positively with irradiation time. However, phenanthrene was rather persistent under irradiation, with less than 25% decline in exposure concentrations after 93 h. Neonates were not immobilized at maximum aqueous solubility of phenanthrene. Rate constants (k) for the photodegradation of pentachlorophenol at 0.41, 0.59, 1.1, and 2.1 mg l(-1) were in the range of 7.2 × 10(-2) and 4.9 × 10(-2)h(-1), showing a slight decrease with increasing initial pentachlorophenol concentration. Nonetheless, pentachlorophenol degradation in the studied concentration range could still be described by the pseudo-first-order kinetics. K values for phenanthrene at 0.12 and 0.22 mg l(-1) were 2.9 × 10(-3)h(-1) and 4.2 × 10(-3)h(-1), respectively.