Extraction and characterization of hydroxyapatite-based materials from grey triggerfish skin and black scabbardfish bones

The conversion of food industry by-products to compounds with high added value is nowadays a significant topic, for social, environmental, and economic reasons. In this paper, calcium phosphate-based materials were obtained from black scabbardfish (Aphanopus carbo) bones and grey triggerfish (Balistes capriscus) skin, which are two of the most abundant fish by-products of Madeira Island. Different calcination temperatures between 400 and 1000°C were employed. Materials obtained from calcination of bones of black scabbard fish were composed by homogeneous mixtures of hydroxyapatite (Ca₁₀(PO4)₆(OH)₂, HAp) and β-tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP). Because of the high biocompatibility of HAp and the good resorbability of β-TCP, these natural biphasic materials could be very relevant in the field of biomaterials, as bone grafts. The ratio between HAp and β-TCP in the biphasic compound was dependent on the calcination temperature. Differently, the material obtained from skin of grey triggerfish contained HAp as the main phase, together with small amounts of other mineral phases, such as halite and rhenanite, which are known to enhance osteogenesis when used as bone substitutes. In both cases, the increase of calcination temperature led to an increase in the particles size with a consequent decrease in their specific surface area. These results demonstrate that from the fish by-products of the most consumed fishes in Madeira Island it is possible to obtain bioceramic materials with tunable composition and particle morphology, which could be promising materials for the biomedical field.     

Multi‐scale Approach to Hydrological Classification Provides Insight to Flow Structure in Altered River System

Rivers are hierarchical systems exhibiting processes and patterns across spatial and temporal scales principally driven by changes in flow. Hydrological indices estimated with mean or median daily flow data (i.e. daily scale) may be insensitive to anthropogenic alteration that imparts sub‐daily variation to flow. Therefore, indices developed at multiple temporal resolutions may provide additional insight into the presence of flow patterns masked by traditional techniques. We characterized the flow regime along the longitudinal gradient of the Platte River, a large Great Plains USA river, using hydrological indices derived with mean daily and sub‐daily flow data and a combination of multivariate statistical techniques. Three unique flow units were evident using daily scale flow data, whereas six unique flow units were evident at the sub‐daily scale. Flow units at both scales were not static, but rather the presence and extent of flow units across the riverscape depended on climate, tributary inflows and human influence. Anthropogenic alteration including hydropeaking was evident at the sub‐daily scale but not at the daily scale. The full complement of flow structure within regulated rivers, therefore, may not be captured using mean or median daily discharge values alone. Inductive river classification studies may benefit from assessing hydrological indices at multiple scales, particularly when investigating river systems with anthropogenic modification such as hydropeaking. Copyright © 2016 John Wiley & Sons, Ltd.     

闽江下游径流量和北港分流比变化及其对水龄的影响研究

利用闽江下游多年水文资料,分析了干流流量时空变化和北港分流比变化趋势,并借助EFDC模型研究水口水库下泄流量和北港分流比对闽江下游水体水龄的影响。分析表明:闽江干流径流量年际变化不均匀,北港分流比则经历了由小变大再变小的趋势。模拟的闽江水龄结果可知水龄与下泄流量成反比关系,北港分流比减小将增加北港水体交换时间,同时减少南港水体交换时间;水龄可以定量地描述污染物在北港河道的停留时间,为保障北港水源地水质安全,需要增大枯水期上游水口水库下泄流量和增大北港分流比。     

含植物明渠流动分区和特征尺度研究进展

植物是生态河流必不可少的要素之一。植物的存在,改变了水流的紊流结构。由于流动沿垂向具有较强的不均匀性,对于含植物明渠紊流统计特性的描述,至今未有公认的、统一的沿水深分布表达形式。因此,对含植物明渠流动分区和各区特征尺度的研究越来越受到重视。本文回顾了无植物明渠和含植物明渠流动分区及特征尺度研究的主要成果,重点对基于流速分布和紊流结构两种方法确定的分区和特征尺度进行了分析和总结。指出将涡结构与流动特性参数分布规律相结合进行流动分区,在各区确定合适的特征尺度,进一步探究分区界限及流动特征尺度的影响因素及具体影响,建立普适的紊流统计特性分布规律是今后含植物明渠紊流结构研究的重要内容和趋势。     

基于小波变换的开都河径流量多时间尺度分析

以开都河大山口站1956—2006年的年径流量资料为例,利用Morlet小波变换对其水文序列的多时间尺度演变特性进行了分析,并预测了开都河2006年以后的年径流量变化趋势。结果表明:开都河存在6 a、10 a、15 a和38 a等4个主周期,其中38 a和10 a分别为第一和第二主周期;2006年后的未来几年内开都河将处于偏枯期。     

不同规模地质体剩余油的形成与分布研究

针对非均质多层砂岩油田高含水期剩余油分布的复杂性,通过室内物理模拟实验、检查井资料分析、矿场剩余油综合分析,从宏观到微观对油藏规模级、油层规模级、层内规模级和孔隙规模级等4种不同规模地质体剩余油的影响因素进行分析,研究不同规模地质体剩余油的形成、分布特征及成因类型.针对不同规模地质体的剩余油类型,指出相应的挖潜方法.图4表2参39     

垂直激励圆柱形容器中的表面波结构

本文利用奇异摄动理论的两时间变量展开法，研究了垂直强迫圆柱形容器中的单一水表面驻波模式。假设流体是无粘、不可压且运动是无旋的，在忽略了表面张力的影响下，得到一个具有立方项以及底部驱动项影响的非线性振幅方程。对上述方程进行了数值计算，研究了特定(9，6)模式的表面驻波结构和特性，如驻波的节点分布及驻波随某些参数的变化规律等，从计算的等高线的图象来看，和以往的实验结果相当吻合。     

Comparison of oxidation behaviours among three Fe–Cr based alloys for solid oxide fuel cell interconnect

Abstract

Two metallic alloys, containing comparable amounts of Cr, underwent oxidation in hot air simulating (the solid oxide fuel cell cathode atmosphere) for various periods. The results demonstrated that the oxidation kinetics of Crofer22 APU and equivalent ZMG232 followed the parabolic rate law and oxidation rates increased with temperature. Typical oxidation rates of Crofer22 APU and ZMG232 upon annealing treatment are approximately 0·21 orders of magnitude lower than that of ZMG232. An oxide scale electron probe microanalyser, a scanning electron microscope and X-ray diffractometer were adopted to verify the applicability of Fe–Cr based alloys in the solid oxide fuel cell interconnect component. Two alloys contain comparable amount of Cr, Mn and Fe, and their surface oxides as analysed are indicated to be Cr₂O₃ and (Mn,Fe)Cr₂O₄ spinel compound. In summary, Crofer22 APU had the best oxidation resistance of any of the alloys of interest.     

小型亚热带半日潮河口中的湍流

在天然河口,污染物的输送是由湍流动量混合驱动的,而弥散的大小却难以被准确地预测。这是由于对河口的湍流结构缺乏基础的认识而造成的。介绍在一个小型的亚热带半日潮河口进行的高频率及连续50 h的湍流实地测量的情况。在研究的浅水(低潮水深小于0．5 m)小型河口中,使用了最适用于这种水体的声学多普勒流速仪进行测量,并进行了完整的后处理工作。河口水流是一个波动的过程,各种宏观流动参数随潮周期和其它大尺度的过程而波动,但是湍流特性是由即时局部流动特性所决定,它们基本不受流动历程的影响,其结构和瞬时变化受多种机理影响。这导致其只与水流剪切力引起的湍流边界层平衡相关。所有湍流特性在潮周期中均有大波动是本次研究数据的一个显著特征,这一特征在此前少有记载,但本次的测量数据与过往数据的一大差别是,数据连续测量的时间长且频率高。这将为波动特性的动量交换系数及积分时间和长尺度提供新的信息,这些湍流特性不应被视为不变的。     

Effects of free stream turbulence on a turbulent boundary layer on a flat plate with zero pressure gradient part IV: Calculation of the flow field

The effects of free stream turbulence on a turbulent boundary layer were calculated by using a k-ϵ two-equation model. The calculations were performed with respect to velocity profiles on a flat plate, wall shear stress, turbulence energy, integral length scales of turbulence, and decay of free stream turbulence, and the results were compared with the experimental results. The energy of the free stream turbulence and the dissipation values at the leading edge of the flat plate were used as the initial calculation conditions. These initial values of dissipation were determined from the integral length scales of the free stream turbulence at the leading edge. The calculated wall shear stress increased with the free stream turbulence and integral length scales of turbulence. The velocity profiles and turbulence energy agreed well with the experimental results, and the effects of free stream turbulence on the wall shear stress agreed fairly well with those observed in experiments. © 1997 Scripta Technica. Inc. Heat Trans Jpn Res. 25 (2): 65–75, 1996