When nanoparticle conductive ink is used for printing interconnects, cracks and pores are common defects that deteriorate the electrical conductivity of the printed circuits. Influences of the ink solvent, the solid f...
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When nanoparticle conductive ink is used for printing interconnects, cracks and pores are common defects that deteriorate the electrical conductivity of the printed circuits. Influences of the ink solvent, the solid fraction of the ink, the pre-printing treatment and the sintering parameters on the interconnect morphology and conductivity were investigated. It was found that the impacts of all these factors coupled with each other throughout the whole procedure, from the pre-printing to the post-printing processes, and led to a structure inheritance effect. An optimum process route was developed for producing crack-free interconnects by a single-run direct-writing approach using home-made nano-copper ink. A weak gel was promoted in the ink before printing in the presence of long-chain polymers and bridging molecules by mechanical agitation. The fully developed gel network prevented the phase separation during ink extrusion and crack formations during drying. With the reducing agents in the ink and slow evaporation of the ink solvent, compact packing and neck joining of copper nanoparticles were obtained after a two-step sintering process. The crack-free interconnects successfully produced have a surface roughness smaller than 1.5 m and the square resistances as low as 0.01 /.
Reverse transformation at 725-800 degrees C x 0-35 s from a ferrite/pearlite to austenite was investigated in spring steel 60Si2MnA with various pearlite fineness obtained by isothermal transformation. Then, its influ...
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Reverse transformation at 725-800 degrees C x 0-35 s from a ferrite/pearlite to austenite was investigated in spring steel 60Si2MnA with various pearlite fineness obtained by isothermal transformation. Then, its influence on the structure inheritance in the spring steel during heat treatment process was discussed. The results indicated that various pearlite fineness influences clearly start temperature of the reverse transformation. Austenite preferentially nucleates at the ferrite/cementite interface within pearlite, the neighboring pearlite colony boundary and the proeutectoid ferrite/pearlite boundary during the reverse transformation process. And the angle between pearlite lamellae and austenite growth direction has an important influence on austenite growth rate. Besides, the ferrite/pearlitic structure has structure inheritance phenomenon, because various hot-rolled microstructure affect the austenite nucleation and growth during heat treatment process.
Chemical reactions between oil-sands and injected steam or steam condensate during cyclic steam stimulation (CSS), commonly used to mobilize heavy oil and bitumen, result in decomposition of pre-existing minerals and ...
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Chemical reactions between oil-sands and injected steam or steam condensate during cyclic steam stimulation (CSS), commonly used to mobilize heavy oil and bitumen, result in decomposition of pre-existing minerals and formation of new phases including clay minerals. These changes can reduce reservoir permeability and limit hydrocarbon recovery. In this study, the chemical and stable isotope compositions of berthierine and smectitic clay minerals contained in pre-and post-steam Clearwater Formation oil-sands from Cold Lake, Alberta were analyzed to investigate how these phases were affected by CSS. Berthierine abundance in the injection-zone decreased after steaming whereas the abundance of smectitic clay minerals increased. Pre-and post-steam berthierine exhibited the same range of chemical compositions, while those of pre-and post-steam smectitic clay minerals commonly differed. Some post-steam smectitic clay minerals from the steam injection-zone, in particular, contain significantly more Fe and Si but less Al than pre-steam samples. It is proposed that that berthierine contributed to the formation of new smectitic clay minerals during CCS through partial inheritance of the berthierine 1:1 structure. This inheritance model approximates the unique chemical compositions of the post -steam smectitic clay minerals. The model also helps to explain the incomplete oxygen and hydrogen isotope exchange between injection fluids and smectitic clay minerals formed during CSS.
Loess structure plays a vital role in the evolution of loess landforms, which mainly involves water erosion and slope collapse processes. The existing literature on loess structure lacks a comprehensive and systematic...
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Loess structure plays a vital role in the evolution of loess landforms, which mainly involves water erosion and slope collapse processes. The existing literature on loess structure lacks a comprehensive and systematic overview covering structural characteristics and features at all relevant spatial scales and explaining how they underlie these processes. This paper presents a detailed discussion of loess structure from this perspective and proposes a structural classification over three contiguous ranges of spatial scales (micro-, meso- and macro-) in terms of nature of particles and pore patterns. Then it details how the initial loess structure is modified by various environmental processes, and outlines cross-scale relations of inheritance among the solid structural elements (microscopic particle assemblies, mesoscopic fragments and macroscopic blocks) and weak segments (pores, channels, pipes, biological pores, abiogenic joints and cracks) making up the present-day loess structure. The ascending impact of ubiquitous micro-scale structure is evidenced by similarity in shapes and spatial arrangement patterns of all features across the scale ranges. Vertically aligned strong units (particle assemblies) coupled with vertically aligned weak segments (pores) defining micro-scale loess structure set the stage for the formation of the structural elements at larger scales. This structure, named as "vertiloess", extends to field-scale landforms (>10 m) bounded and shaped with vertical features throughout the loess plateau.
Nanoporous metals show great potentials in various applications including catalysis, sensing, actuation and supercapacitors. The liquid Ga-assisted alloying/dealloying strategy is a feasible and scalable way to fabric...
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Nanoporous metals show great potentials in various applications including catalysis, sensing, actuation and supercapacitors. The liquid Ga-assisted alloying/dealloying strategy is a feasible and scalable way to fabricate substrate-supported nanoporous metals. However, the influence of intrinsic alloying mode and mechanism on the formation and modulation of nanoporous structure has not been thoroughly explored before. In this work, after painting liquid Ga on Ag foil, both the bulk-like Ag3Ga (in the Ag-rich zone) and wire-like Ag3Ga (in the liquid Ga-rich zone) form owing to the interdiffusion of Ag and Ga atoms. Correspondingly, the bimodal wire-like and unimodal bulk-like nanoporous Ag is obtained because of the structure inheritance during dealloying. In addition, the thickness of alloy layer (nanoporous layer) versus mass loading of liquid Ga follows a good linear relationship. The in-situ X-ray diffraction of dealloying from Ag3Ga to nanoporous Ag illustrates no other intermetallic phase appears and the dealloying process can be described by the dissolution-surface diffusion model. More importantly, the substrate-supported nanoporous Ag exhibits excellent mechanical properties which are of great importance to the future applications of nanoporous metals. (C) 2021 Elsevier B.V. All rights reserved.
The Piani Eterni karst system is one of the longest and deepest caves of Italy situated in the southern sector of the Dolomiti mountain range. The area where the cave was formed displays peculiar structural settings c...
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The Piani Eterni karst system is one of the longest and deepest caves of Italy situated in the southern sector of the Dolomiti mountain range. The area where the cave was formed displays peculiar structural settings confined in a tectonic transpressive corridor between two regional thrusts (Belluno and Valsugana). During Miocene uplift of the range the inheritance of Mesozoic structures led to the formation of a deep and wide upward-branching flower (or palm tree) structure cutting the carbonate sequence and exposing the surrounding surface to karst processes after erosion. The relative lowering of the hydrologic base level, due both to the uplift of the area and then to the carving of deep glacial valleys in the Quaternary, allowed the formation of paleo-phreatic conduits at subsequently deeper levels, interconnected by vadose shafts and canyons. This work gives a detailed tectonic interpretation of the transpressive structure and picks out the tectonic features most favorable to the karst development. A detailed statistical analysis of the distribution and orientation of the karat conduits was performed using 31 km of 3D surveys showing that the development of the cave was strictly guided by a few favorable surfaces of stratigraphic and tectonic origin. These features are known in the literature as inception horizons and tectonic inception features, respectively. Cave levels are usually related to lithologic favorable conditions associated with standings of the paleo-water table. Here we suggest that some tectonic surface geometries could have led to the opening of voids in the active tectonic phase leading to the formation of the original proto-conduit network. Different types of tectonic inception features identified in the cave were described in terms of geometry and kinematics. Tensional fractures, as well as fault plane undulations and flexural slip surfaces between beds, are described as the most favorable tectonic surfaces for the development of the conduit
In this paper we show how to compute the QR-factorization of a rank structured matrix in an efficient way by means of the Givens-weight representation. We also show how the QR-factorization can be used as a preprocess...
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In this paper we show how to compute the QR-factorization of a rank structured matrix in an efficient way by means of the Givens-weight representation. We also show how the QR-factorization can be used as a preprocessing step for the solution of linear systems. Provided the representation is chosen in an appropriate manner, the complexity of the QR-factorization is O((ar(2) + brs + cs(2))n) operations, where n is the matrix size, r is some measure for the average rank of the rank structure, s is some measure for the bandwidth of the unstructured matrix part around the main diagonal, and a, b, c is an element of R are certain weighting parameters. The complexity of the solution of the linear system with given QR-factorization is then only O((dr + es)n) operations for suitable d, e is an element of R. The performance of this scheme will be demonstrated by some numerical experiments.
The dependence of the binding energies in molecules and crystals on the interatomic distances near the equilibrium position was established in the framework of the Mie equation using the force constants of molecules a...
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The dependence of the binding energies in molecules and crystals on the interatomic distances near the equilibrium position was established in the framework of the Mie equation using the force constants of molecules and the elasticity moduli of solids. To evaluate the repulsion forces, we used the Morse function for molecules and the Born-Lande approach for ionic crystals.
In this paper, we show how to perform the Hessenberg reduction of a rank structured matrix under unitary similarity operations in an efficient way, using the Givens-weight representation. This reduction can be used as...
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In this paper, we show how to perform the Hessenberg reduction of a rank structured matrix under unitary similarity operations in an efficient way, using the Givens-weight representation. This reduction can be used as a first step for eigenvalue computation. We also show how the algorithm can be modified to compute the bidiagonal reduction of a rank structured matrix, this latter method being a preprocessing step for computing the singular values of the matrix. For the main cases of interest, the algorithms we describe in this paper are of complexity O((ar + bs) n(2)), where n is the matrix size, r is some measure for the average rank index of the rank structure, s is some measure for the bandwidth of the unstructured matrix part around the main diagonal, and a,b is an element of R are certain weighting parameters. Numerical experiments demonstrate the stability of this approach.
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