DNA-directed magnetic network formations with ferromagnetic nanoparticles

We formed a DNA network embedding ferromagnetic cobalt nanoparticles with a 12-nm diameter through a nanoscale self-assembly of DNA molecules on large-scale mica surfaces (12 mm x 12 mm); we then confirmed its structural characteristics with an atomic force microscope. Moreover, noncontact magnetic force microscope measurement revealed that some embedded cobalt nanoparticles have different directions of magnetization, similar to "bits" in magnetic data storage devices.     

The optical properties of long-lived luminous formations

Luminous formations initiated by electric discharge appear differently depending on the intrinsic luminosity, external illumination, and the background color. These formations simultaneously exhibit four colors: red, yellow, violet, and blue. These colors are known to be typical of the ball lightning (BL) possessing, according to the available statistics [1], a short lifetime. At the same time, it was stated [2] that there is BL of two types: short-and long-lived. Based on the results obtained, it is suggested that the short-lived BL must also exhibit all four colors simultaneously.     

The possibility of influencing vortex atmospheric formations

Video filming is used to investigate the possibility of influencing the characteristics of free concentrated vortexes generated under laboratory conditions over a heated underlying surface. The method of influencing consists in arranging obstacles in the form of vertical nets of different geometries in the path of air vortex.     

Interfacial formations in extraction systems with HDEHP and TBP

The kinetics of the accumulation of Er(III), Ho(III), Pr(III), Nd(III), and Yb(III) in the interfacial layer of the extraction system with HDEHP or TBP in a nonaqueous diluent (heptane, toluene, tetrachloromethane), responsible for the appearance of interfacial formations, was studied, and the process mechanism was suggested. Up to 30% of the initial amount of the extractable element in the aqueous phase can be accumulated in the dynamic interfacial layer (DIL) when using HDEHP as extractant, and up to 15%, in the systems with TBP. The time dependences of the accumulation of lanthanide di(2-ethylhexyl) phosphates are characterized by the presence of a horizontal plot, i.e., the process in this period is steady-state. The accumulation in DIL depends on the initial concentration of the extractable element, extraction reagent, and solution acidity. In systems with the more polar diluent, the accumulation of the rare earth element in DIL is smaller.     

Un extensomètre à béton éliminant l'influence des déformations transversales sur la mesure des déformations longitudinales

Résumé L'extensomètre présenté ici se distingue des matériels équivalents habituellement rencontrés par le fait qu'il a été introduit un degré de liberté entre le système de fixation sur l'éprouvette et le système de mesure de déformation longitudinale, ceci afin de permettre la libre dilatation du cylindre de béton. Le souci permanent lors de la conception de l'appareil a été d'en faire un instrument très facile et très rapide à mettre en place sans exiger de préparation particulière de l'éprouvette tout en donnant des résultats aussi fiables qu'avec des mesures par jauges résistives. Cet appareil doit permettre des analyses très fines en chargement cyclique et dans le domaine des grandes déformations.

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Summary This strain gauge differs from equipment normally used, since it allows a degree of freedom between the test piece fixing system and the longitudinal deformation measuring system, thus ensuring free expansion of the concrete cylinder. The designers constant concern was to provide an instrument for easy and quick installation without requiring special test piece preparation, yet ensuring results as reliable as those obtained with resistive gauges. With this apparatus it is possible to undertake very close analyses in cyclic loading and in the field of large deformations.

     

Microscopic observations of unreported crystalline formations in polycarbonate and polysulphone

Apparent crystalline entities, not previously reported, have been observed in both polycarbonate and polysulphone; these are described and compared to similar entities reported for other polymers.     

An inverse-source problem for maximization of pore-fluid oscillation within poroelastic formations

This paper discusses a mathematical and numerical modeling approach for identification of an unknown optimal loading time signal of a wave source, atop the ground surface, that can maximize the relative wave motion of a single-phase pore fluid within fluid-saturated porous permeable (poroelastic) rock formations, surrounded by non-permeable semi-infinite elastic solid rock formations, in a one-dimensional setting. The motivation stems from a set of field observations, following seismic events and vibrational tests, suggesting that shaking an oil reservoir is likely to improve oil production rates. This maximization problem is cast into an inverse-source problem, seeking an optimal loading signal that minimizes an objective functional – the reciprocal of kinetic energy in terms of relative pore-fluid wave motion within target poroelastic layers. We use the finite element method to obtain the solution of the governing wave physics of a multi-layered system, where the wave equations for the target poroelastic layers and the elastic wave equation for the surrounding non-permeable layers are coupled with each other. We use a partial-differential-equation-constrained-optimization framework (a state-adjoint-control problem approach) to tackle the minimization problem. The numerical results show that the numerical optimizer recovers optimal loading signals, whose dominant frequencies correspond to amplification frequencies, which can also be obtained by a frequency sweep, leading to larger amplitudes of relative pore-fluid wave motion within the target hydrocarbon formation than other signals.     

海底声学探测与底质识别技术的新进展

文章介绍了海底声学探测与底质识别技术的现状及最新进展。重点介绍线性调频声呐（CHIRP）技术和非线性调频声呐技术（参量阵声呐）在海底沉积层结构、海底地形地貌探测及其在海底沉积物的底质属性分类识别方面的应用。并简要介绍国内外在线性和非线性调频声呐技术及用于沉积物属性识别方面的最新专利技术或最新进展。     

Elastic instabilities,microstructure transformations,and pattern formations in soft materials

Large deformations of soft materials can give rise to the development of various elastic instabilities. The phenomenon is associated with a sudden and dramatic change in structure morphologies. The underlying mechanism is crucial for the formation of complex morphologies in biology. Moreover, the concept of instability-induced pattern transformations is promising for designing novel materials with switchable functions and properties. In this paper, we review the state of the art in elastic instability phenomena in soft materials. We start by considering the classical buckling in beam-based structure lattice designs. Then, we discuss the instability-induced microstructure transformations in soft porous materials, and heterogeneous multiphase and fiber composites. Next, the mechanisms – often involving the post-buckling consideration – leading to the wrinkling and folding, creasing, fringe, and fingering are discussed.     

Irradiance formations in hollow straight light pipes with square and circular shapes

We investigated, both analytically and numerically, the irradiance formation of an asymmetrically located Lambertian light source in hollow straight light pipes with square and circular shapes. The uniform irradiance distribution in a square light pipe and hot-spot localization in a circular light pipe were examined and determined semianalytically. Typical factors of influence, such as light-pipe length, width, and source size, were identified with extensive simulation. When the ratio of light-pipe length and width was less than 0.5, the deviation from uniformity could be more than 20%. But once the source size was large enough (approximately half of the incident port), such that the Lambertian characteristics of the source dominated the irradiance distribution, the uniformity deviation was reduced. Furthermore, a quantity of root-mean-square circular differences was defined in order to identify the shape deformation of the light pipe; it was found that the peak value of the hot spot decreased exponentially with the deformation scale. The influence of nonperfect reflectivity of the pipe wall on irradiance formation was also examined for a square light pipe; when the reflectivity is larger than 90%, the difference in uniformity is less than 10% and uniform irradiance remains, provided that the ratio of light-pipe length and width is larger than 1; even the source is located asymmetrically.     

Irradiance formations of on-axis Lambertian pointlike sources in polygonal total-internal-reflection straight light pipes

Different geometric shapes of light pipes cause different irradiance distributions. We analytically explore the irradiance distributions of on-axis Lambertian pointlike sources in polygonal total-internal-reflection (TIR) straight light pipes. It is analytically shown that the irradiance of pentagonal light pipes concentrates on the center of the exit plane. Numerical verifications are also provided, and experimental explorations with different shapes of acrylic light pipes are carried out for comparison. We also analyze the influence of light-pipe length on distribution uniformity and deduce the smallest uniform-mixing length/circumradius ratios for polygonal light pipes.     

Mesure des déformations du béton au jeune âge

Résumé Les déformations du béton au jeune age peuvent être à l’origine de désordres importants. Leur modélisation nécessite une expérimentation sur éprouvette liée à certaines difficultés propres aux caractéristiques du béton jeune. Le capteur à inclure dans le béton frais utilisé dans cette étude se trouve dans le commerce. Celui-ci, ainsi que le moule utilisé pour confectionner l’éprouvette, ne doivent pas trop perturber les déformations du béton jeune. Une modélisation par éléments finis de ce système capteur éprouvette est présentée. Celle-ci montre comment est modifié le champ de déformation, ce qui permet certaines corrections des mesures délivrées par ce type de capteur. Deux cas sont considérés: l’étude des déformations, sans charge extérieure, sous l’effet de variations de température (les éprouvettes sont alors confectionnées dans un moule souple en PVC en forme de soufflet) et l’étude des déformations d’un cylindre de béton sous un chargement uniaxial.

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Summary Strains in concrete at an early age can cause major damage. Modelling them calls for experiments on specimens, with attendant difficulties specific to the characteristics of young concrete. The sensor embedded in the fresh concrete in this study is commercially available. It and the mould used to make the specimen must not perturb the strains of the young concrete too much. A finite-element model of this sensor-specimen system is presented. It shows how the strain field is modified, making possible some corrections of the measurements delivered by this type of sensor. Two cases are examined: study of the strains, without external loads, resulting from temperature variations (for which the specimens are made in a bellows-shaped flexible PVC mould), and study of the strains of a concrete cylinder under uniaxial loading.

     

Measurements of the suitability of large rock salt formations for radio detection of high-energy neutrinos

We have investigated the possibility that large rock salt formations might be suitable as target masses for detection of neutrinos of energies about 10 PeV and above. In neutrino interactions at these energies, the secondary electromagnetic cascade produces a coherent radio pulse well above ambient thermal noise via the Askaryan effect. We describe measurements of radio-frequency attenuation lengths and ambient thermal noise in two salt formations. Measurements in the Waste Isolation Pilot Plant, located in an evaporite salt bed in Carlsbad, NM yielded short attenuation lengths, 3–7 m over 150–300 MHz. However, measurements at United Salt's Hockley mine, located in a salt dome near Houston, Texas yielded attenuation lengths in excess of 250 m at similar frequencies. We have also analyzed early ground-penetrating radar data at Hockley mine and have found additional evidence for attenuation lengths in excess of several hundred meters at 440 MHz. We conclude that salt domes, which may individually contain several hundred cubic kilometer water-equivalent mass, provide attractive sites for next-generation high-energy neutrino detectors.     

Simulating the implications of oxide scale formations in austenitic steels of ultra-supercritical fossil power plants

Formation of steam-side oxide scale that can cause major failures in boilers is a large concern in fossil-fueled power plant operation. In this work, we attempt to simulate the implications of oxide scale formation and subsequently assumed exfoliation in the given length of an austenitic tube of ultra-supercritical (USC) fossil power plants under different presumed service conditions. The incremental procedures used to determine the average metal temperature and scale thickness over a period of time in superheater/reheater tubes at a specified steam temperature are presented. A number of simulation results for both formation and subsequent exfoliation of the oxide scales are presented and discussed. Based on the simulation results, the estimated scale growth and presumed exfoliation rate in austenitic steels at 650 °C seemed to be allowable. However, to run USC power plants with steam condition of around 650 °C, more detailed studies are required.     

Effect of gas phase on SiC and Si3N4 formations from SiO2

During the synthesis of SiC, Si₃N₄ and sialon whiskers by carbothermal reduction of SiO₂, a localized formation of amorphous phases or Si₂N₂O powders was observed beneath these whiskers. Because these whiskers were formed by the vapour/solid mechanism, the controlling gas phase was of primary importance to obtain whiskers of tailored morphology and chemistry. To elucidate the effect of the gas phase composition on the reaction mechanisms of SiC and Si₃N₄, the oxygen partial pressure was measured during the synthesis with a ZrO₂ solid electrolyte. The carbothermal reduction of SiO₂, as well as evolution of gases, were accelerated by a formation of a molten fluorosilicate with an auxiliary halide bath. The oxygen partial pressure steadily increased with increasing temperature and reached a maximum level of 10^–1110^–12 atm in the early stage of reaction at 1623 K, then decreased again towards the end of reaction in both cases. Effects of the gas phase on the SiC and Si₃N₄ formations were not the same: p _CO and and their ratio were important factors in the SiC formation, while the higher formed an oxynitride phase in the Si₃N₄ formation.