Hydromorphological,hydraulic and ecological effects of restored wood: findings and reflections from an academic partnership approach

Large wood (re)introduction can deliver multiple benefits in river restoration, but there is a dearth of the detailed and longer‐term post‐project monitoring and evaluation required for improving best practice. We present findings from an academic partnership approach to post‐project evaluation, based on successive MSc research projects on restored large wood in the Loddon catchment, UK. Field and modelling data reveal: (i) key differences in large wood features between restored and natural reaches; (ii) increased hydraulic retention and changes to mesohabitats associated with large wood; (iii) differences in macroinvertebrate community composition around large wood but a lack of site‐level effects; (iv) interactions between macrophytes and large wood that may be specific to restored reaches; (v) a need for further field and modelling studies to inform the accurate representation of large wood in hydraulic models. Some key challenges in partnership working are identified to aid planning and effectiveness of future collaborations.     

设计资本

UN设计六步法(或多或少)现如今,建筑学科敞开大门接受彻底变革的可能性.那些关于收益和增长的叙述曾在过去几十年中,阐释并大力推进建筑学的发展,并为其提供了合理的依据;如今这些叙述已被打断.现在的焦点在于,如何对建筑核心领域内的一切可能的重要因素提炼阐明新的概念.一切事,是的,所有一切事都可以进行改变,整个世界需要共同面临的问题和需求如此之大.意识到这一挑战还需要了解其有益的潜力;新颖引领建筑学蓬勃发展.如果缺乏连续的物质、文化和意识上的创新,行业便失去其特殊性,而成为建筑行业中平淡无奇的一部分.通过UNStudio,我们早就意识到了这一点,这就是为什么我们在许多不同的方向上推动自己,不断应对新的挑战和问题.但与此同时,这一实验态度也使我们有意识地致力于尽可能多的建造.在全球化经济的背景下,脱离建筑行业的危险性从来就不是我们的首选方案.     

Bolted tension flanges joining square hollow section members

Tests and theoretical analysis on the maximum strength of high strength bolted tension flanges joining square hollow section members have been carried out. Yield line theory has been applied in a similar way to that presented in a previous paper. Correlation between test results and theoretical predictions is quite satisfactory. Based on this study, a simple design formula has been proposed.     

碳纤维增强卷边槽形钢柱的非线性性能和承载力

对碳纤维增强卷边槽形钢柱的试验结果、非线性性能的数值分析以及承载力进行研究。基于GBT的基础研究,涉及柱弹性抗弯性能的研究集中在下列方面:i)布的位置(腹板、翼缘、卷边);ii)碳纤维的方向(纵向、横向或倾斜)以便对加固效果(性能价格比)进行优化。对19个端固定的短、长卷边槽形钢柱的试验过程进行描述。采用碳纤维布对钢柱的不同部位(腹板、翼缘、卷边)进行加固,纤维的方向包括纵向和横向:因为研究的目标是评估碳纤维加固对柱的结构响应的影响,对未加固钢试件也进行了试验。基于壳有限单元模型并采用Abaqus规定,由包含非线性平衡路径(荷载与轴向压缩的比值)和极限强度(大部分与局部/屈曲失稳破坏机理相关)组成的试验结果被用于校准和验证几何及物理非线性数值分析。最后,根据试验和数值结果,对于受到局部/屈曲失稳影响的卷边槽形钢柱,得出碳纤维布加固的有效位置和纤维方向的相关结论。     

Effects of transverse welds on aluminum alloy columns

This paper investigates the effects of transverse welds on aluminum alloy columns. The materials of the specimens were 6063-T5 and 6061-T6 heat-treated aluminum alloys. Various coupon tests were performed to obtain the non-welded and welded material properties of aluminum alloys. An accurate and reliable finite element model (FEM) was used for the simulation of aluminum alloy stub columns of square and circular hollow sections (SHS, CHS) in this study. The stress–strain relationships obtained from the coupon tests were incorporated in the FEM. A parametric study was conducted that included 48 columns of different section shapes with and without transverse welds at the ends of the columns. This study focused on the effects of transverse welds on column strengths with respect to the section slenderness. Hence, the parametric study was performed on stub columns of SHS and CHS in constant column length. The European Code for aluminum structures uses the heat-affected zone (HAZ) softening factor to consider the weakening effects of transverse welds on column strength. The HAZ softening factors obtained from the parametric study were compared with the corresponding values specified in the European Code. HAZ softening factors were proposed in this study.     

RURAL-URBAN MIGRATION AND SELF-SELECTION IN TUNISIA

This article presents a model of returns to rural-urban migration accounting for self-selection of migrants using survey data from Tunisia. Of particular interest in this research is the sign and significance of the selectivity terms in the mover and the stayer group. The model focuses on the importance of human capital investment incentives and personal characteristics. This article is organized as follows. Section 2 presents the Tunisian context. Section 3 describes a simple model of migrant behavior in which the decision to migrate, viewed in the context of investment in human capital, results as the solution to an optimal control problem. Section 4 provides details of a simultaneous equation model, which incorporates the decision to migrate, returns to migration, and self-selection. The results of the research lead to the conclusion that by purely statistical assessment the expected monetary gain effect is significantly different from zero. Although by economic considerations, it is small. This low effect is a result of the omission of other relevant variables from the analysis of rural-urban migration in Tunisia. In the migration-earning equations the selectivity variable is not significant, whereas there is a strong evidence of positive self-selection in the earnings of nonmigrants.     

CFD and experimental investigation of the gas–liquid flow in the distributor of a compact heat exchanger

High performance of compact heat exchangers is conditioned by correct fluid distribution. This is especially true for gas–liquid heat exchangers where a uniform distribution is particularly delicate to obtain and where maldistribution entails significant performance deterioration. Several phenomena can lead to phase distribution problems: the fins may be subject to manufacturing defects or fouling, leading to shortcuts or dead zones. But the first source of maldistribution may be a poor distribution at the outlet of the entrance distributor. This distributor aims at mixing the phases and distributing them across the channels.     

The Synthesis and Biological Evaluation of Multifunctionalised Derivatives of Noscapine as Cytotoxic Agents

Noscapine, a phthalideisoquinoline alkaloid derived from Papaver somniferum, is a well‐known antitussive drug that has a relatively safe in vitro toxicity profile. Noscapine is also known to possess weak anticancer efficacy, and since its discovery, efforts have been made to design derivatives with improved potency. Herein, the synthesis of a series of noscapine analogues, which have been modified in the 6′, 9′, 1 and 7‐positions, is described. In a previous study, replacement of the naturally occurring N‐methyl group in the 6′‐position with an N‐ethylaminocarbonyl was shown to promote cell‐cycle arrest and cytotoxicity against three cancer cell lines. Here, this modification has been combined with other structural changes that have previously been shown to improve anticancer activity, namely halo substitution in the 9′‐position, regioselective O‐demethylation to reveal a free phenol in the 7‐position, and reduction of the lactone to the corresponding cyclic ether in the 1‐position. The incorporation of new aryl substituents in the 9′‐position was also investigated. The study identified interesting new compounds able to induce G2/M cell‐cycle arrest and that possess cytotoxic activity against the human prostate carcinoma cell line PC3, the human breast adenocarcinoma cell line MCF‐7, and the human pancreatic epithelioid carcinoma cell line PANC‐1. In particular, the ethyl urea cyclic ether noscapinoids and a compound containing a 6′‐ethylaminocarbonyl along with 9′‐chloro, 7‐hydroxy and lactone moieties exhibited the most promising biological activities, with EC₅₀ values in the low micromolar range against all three cancer cell lines, and these derivatives warrant further investigation.     

Acrylate–vinylidene chloride copolymers derived from corresponding water‐borne latexes: Influence of acrylate units on their potential as heavy‐duty anticorrosive coating materials

A series of aqueous latexes with solid contents of 56%–59% were synthesized by binary emulsion copolymerization of vinylidene chloride (VDC) with an acrylate, namely methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), hexyl acrylate (HA), or 2‐ethylhexyl acrylate (EHA). Differential scanning calorimetry (DSC) and Fourier‐transform infrared (FTIR) spectroscopy showed that the acrylate units with short ester side‐chains, such as MA and EA, made the copolymers hard and the crystallization tendency of their PVDC segments was reduced. Hydrophobic acrylates with relatively long ester groups, such as HA and EHA, gave flexible copolymers, and favored the crystallization of their PVDC segments. BA endowed the copolymers with medium flexibility and crystallization tendency. As coating materials, the copolymers bearing MA and EA adhered poorly to the tinplate before or after 100 hr of salt‐spray corrosion, whereas those bearing BA, HA, or EHA showed good adhesion to tinplate when they had little or no crystallinity. After 100 hr of salt‐spray corrosion, only BA–VDC80, containing 80% VDC, retained both excellent adhesion to metal and excellent barrier performance. Further study demonstrated that BA–VDC80 could protect tinplate from rusting for at least 250 hr under harsh salt‐spray corrosion. Scanning electron microscopy, FTIR‐attenuated total reflectance spectroscopy and DSC were used to evaluate the corroded BA–VDC80 film. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40192.