Direct observation of continuous electric dipole rotation in flux-closure domains in ferroelectric Pb(Zr,Ti)O₃

Low-dimensional ferroelectric structures are a promising basis for the next generation of ultrahigh-density nonvolatile memory devices. Depolarization fields, created by incompletely compensated charges at the surfaces and interfaces, depress the polarization of such structures. Theory suggests that under conditions of uncompensated surface charges, local dipoles can organize in flux-closure structures in thin films and vortex structures in nano-sized ferroelectrics, reducing depolarization fields. However, the continuous rotation of the dipoles required in vortex structures and the behavior of unit cell dipoles in flux-closure structures have never been experimentally established. By aberration-corrected transmission electron microscopy, we obtained experimental evidence for continuous rotation of the dipoles closing the flux of 180° domains in a ferroelectric perovskite thin film.     

Paired-end mapping reveals extensive structural variation in the human genome

Structural variation of the genome involves kilobase- to megabase-sized deletions, duplications, insertions, inversions, and complex combinations of rearrangements. We introduce high-throughput and massive paired-end mapping (PEM), a large-scale genome-sequencing method to identify structural variants (SVs) approximately 3 kilobases (kb) or larger that combines the rescue and capture of paired ends of 3-kb fragments, massive 454 sequencing, and a computational approach to map DNA reads onto a reference genome. PEM was used to map SVs in an African and in a putatively European individual and identified shared and divergent SVs relative to the reference genome. Overall, we fine-mapped more than 1000 SVs and documented that the number of SVs among humans is much larger than initially hypothesized; many of the SVs potentially affect gene function. The breakpoint junction sequences of more than 200 SVs were determined with a novel pooling strategy and computational analysis. Our analysis provided insights into the mechanisms of SV formation in humans.     

Leaf-to-fruit ratio affects water and dry-matter content of mango fruit

Summary

Changes in water and dry-matter content of developing mango fruit (Mangifera indica L. ‘Lirfa’) were investigated over a single season in Réunion Island, along with the effects of leaf:fruit ratio (10, 25, 50, 100 and 150 leaves per fruit on girdled branches). As the fruit developed, about 8–13% of fruit water weight was in the peel compared with 78–86% in the pulp and 6–9% in the stone. When the data were expressed on a dry-weight basis, 12–20% was in the peel, 60–70% was in the pulp and 18–20% in the stone. At harvest, larger fruit, on treatment 100, had a higher proportion of weight in the pulp. Good relationships between water and dry weight of each fruit component were found, regardless of the treatment. They showed that the rate of water accumulation decreased when the dry weight increased and that the dry-matter content increased as the fruit developed as well. Increasing leaf:fruit ratio to 100 leaves per fruit improved fruit yield by 300 g and pulp dry-matter content by 6%, for a total of 550 g and 20% at harvest. Fruit quality as estimated by pulp dry-matter content could be calculated easily during the changes in fruit weight over the season. Moreover, this indicator could be useful to assess the maturity of mango fruit.     

埋地油气管道并行敷设技术发展现状

国内几个大型管道工程项目相继采用并行敷设技术施工。介绍了中亚天然气管道、西部原油成品油管道、大连新港-大连石化原油管道的工程概况。一些学者基于现有标准和规范,分别从工程、经济、安全、设计等角度探讨了油气管道并行敷设管间距的确定原则;一些学者则借助数值模拟计算方法,分析了成品油管道对与其同沟敷设的加热输送原油管道的热力影响规律;另有工程技术人员针对并行敷设技术在具体实施和运用过程中存在的施工、防腐、维修等难题,对施工工艺进行了有益的探索。而综合考虑多种因素对管间距的影响,输气管道与输油管道、输气管道的同沟敷设,以及同沟敷设管道工艺系统和站场设置的优化,将成为油气管道同沟敷设技术领域的新课题。     

Chemical Profiling (HPLC-NMR & HPLC-MS), Isolation,and Identification of Bioactive Meroditerpenoids from the Southern Australian Marine Brown Alga Sargassum paradoxum

A phytochemical investigation of a southern Australian marine brown alga, Sargassum paradoxum, resulted in the isolation and identification of four new (5, 9, 10, and 15) and nine previously reported (1, 2, 6–8, and 11–14) bioactive meroditerpenoids. HPLC-NMR and HPLC-MS were central to the identification of a new unstable compound, sargahydroquinal (9), and pivotal in the deconvolution of eight (1, 2, 5–7, and 10–12) other meroditerpenoids. In particular, the complete characterization and identification of the two main constituents (1 and 2) in the crude dichloromethane extract was achieved using stop-flow HPLC-NMR and HPLC-MS. This study resulted in the first acquisition of gHMBCAD NMR spectra in the stop-flow HPLC-NMR mode for a system solely equipped with a 60 μL HPLC-NMR flow cell without the use of a cold probe, microcoil, or any pre-concentration.     

How timing of stem girdling affects needle xylem structure in Scots pine

While needles represent a proportionally large fraction of whole-plant hydraulic resistance, no studies to date have investigated how source–sink disturbances affect needle xylem structure. In this study, we evaluated structural changes in xylem in current-year needles of Scots pine 227 and 411 days after stem girdling (hereafter referred to as DAG). Maximum and minimum tracheid lumen diameters and therefore also the size of tracheid lumen areas increased in needles 227 DAG compared to control needles. In contrast, tracheid dimensions were similar in needles 411 DAG as in the control needles, but smaller xylem area and lower number of tracheids resulted in the lower theoretical needle hydraulic conductivity of those needles. Several needle xylem parameters were intercorrelated in both control and girdled trees. These observed changes provide a new understanding of the processes that occur following a source–sink disturbance. Considering anatomical parameters such as the number of tracheids, tracheid dimension, or needle xylem area, which are rarely described in physiological studies, could be helpful, for example, in understanding to tree hydraulic systems or for modeling gas exchange. Finally, empirical equations were developed to calculate needle theoretical hydraulic conductivity and the number of tracheids in needles using an easily measurable parameter of needle xylem area.