Six New Diterpene Glycosides from the Soft Coral Lemnalia bournei

A chemical study on the extracts of soft coral Lemnalia bournei resulted in the isolation and identification of six new bicyclic diterpene glycosides including three new lemnaboursides E–G (1–3), and three new lemnadiolboursides A–C (4–6), along with three known lemnaboursides (7–9). Their structures were elucidated by detailed spectroscopic analysis, ECD analysis, chemical methods, and comparison with the literature data. Lemnadiolboursides A–C (4–6) contained a lemnal-1(10)-ene-7,12-diol moiety compared with the lemnaboursides. All these compounds were evaluated for antibacterial activity; cell growth inhibition of A549, Hela, HepG2, and CCRF-CEM cancer cell lines; and inhibition of LPS-induced NO production in RAW264.7 macrophages. The results indicated that compounds 1, 2, and 4–6 exhibited antibacterial activity against Staphylococcus aureus and Bacillus subtilis (MIC 4–16 μg/mL); compounds 1–9 displayed low cytotoxicity on the CCRF-CEM cell lines (IC₅₀ 10.44–27.40 µM); and compounds 1, 2, and 5 showed weak inhibition against LPS-induced NO production (IC₅₀ 21.56–28.06 μM).     

Coherent spin transfer between molecularly bridged quantum dots

Femtosecond time-resolved Faraday rotation spectroscopy reveals the instantaneous transfer of spin coherence through conjugated molecular bridges spanning quantum dots of different size over a broad range of temperature. The room-temperature spin-transfer efficiency is approximately 20%, showing that conjugated molecules can be used not only as interconnections for the hierarchical assembly of functional networks but also as efficient spin channels. The results suggest that this class of structures may be useful as two-spin quantum devices operating at ambient temperatures and may offer promising opportunities for future versatile molecule-based spintronic technologies.     

一种具有实用价值的螺旋线

介绍了一条新型螺旋线，该线有理论推导，可广泛应用于通风机，水泵壳体的型线设计上，有很高的实用价值。该螺旋线能够直接用仪器绘出，可以近似替代其它螺旋线。     

The growth of roots of perennial, Italian, hybrid and annual ryegrasses through a high-strength root medium

Abstract A test for root penetration through a wax disc of known hardness was developed and used with twenty‐five cultivars and twenty‐one breeding lines of perennial, Italian, hybrid and annual ryegrasses. After 42 days, the number of roots reaching the wax disc and the number penetrating the disc were counted. Root diameters were measured using image analysis. The proportion of root penetrations ranged from 0·06 to 0·39 across the cultivars and breeding lines, with substantial variation between replicates and cultivars. Diploid perennial cultivars had the thinnest roots, and there were no consistent differences in root diameter between perennial breeding lines, hybrid ryegrasses and Italian ryegrasses. Roots that penetrated the wax disc increased in diameter, by 0·60 on average, a few millimetres above the wax, and through the wax disc. Diameters below the wax disc were the same as those above the zone of impeded root growth. The increase was caused by an increase in size of the parenchyma cells of the root cortex. An experiment with partially and completely impeded root growth showed that impedance did not change root diameter of new roots, or the distribution of root mass between impeded and unimpeded halves of a root system for plants up to 10 weeks old.     

人乳腺癌细胞、结肠癌细胞和宫颈癌细胞生长曲线测定

为检测比较人乳腺细胞(MDA-MB-231、MCF-7、HBL-100)、人结肠癌细胞(HCT-8)和人宫颈癌细胞(HeLa)生长曲线的差异性.本实验首先常规培养MDA-MB-231、MCF-7、HBL-100、HCT-8和HeLa细胞,然后应用MTT方法测定这几种细胞的生长曲线.在本实验条件下,这几种细胞生长速度从高...     

Factors Affecting Sensory Quality of Cooked japonica Rice

The sensory quality of cooked rice is an important factor in determining its market price, as well as consumer acceptance and breeding efforts aimed at improvement of rice grain quality. In this study,the sensory quality and physicochemical properties of three japonica rice varieties harvested in two different growing locations(Xiangshui and Hangzhou of China) were compared to determine the most important factors affecting the sensory quality. All the three varieties had higher scores for overall sensory quality in Xiangshui than in Hangzhou, indicating that the growing location is a key factor in determining the sensory quality of cooked japonica rice. In addition to growing location, variety(genotype) also had an important effect. Longdao 18 scored the highest for overall sensory quality in the two locations, whereas Longdao 30 had the lowest score in Xiangshui, and both Longdao 20 and Longdao 30 had the lowest scores in Hangzhou. Many physicochemical properties, such as apparent amylose content, protein content, thermal properties and free amino acid contents, showed significant differences between the two locations. Correlation analysis showed that apparent amylose content and protein content had contrasting effects on all the sensory attributes. The overall sensory quality was negatively correlated with protein content(r =-0.89, P 0.01) and positively correlated with gel hardness(r = 0.91, P 0.01),indicating that the protein content and hardness are important physicochemical properties for predicting the sensory quality of japonica rice. These findings will provide guidance for selection from the diverse genotypes available to develop new varieties with the desired eating and cooking quality.     

Ecological degradation in protected areas: the case of Wolong Nature Reserve for giant pandas

It is generally perceived that biodiversity is better protected from human activities after an area is designated as a protected area. However, we found that this common perception was not true in Wolong Nature Reserve (southwestern China), which was established in 1975 as a "flagship" protected area for the world-renowned endangered giant pandas. Analyses of remote sensing data from pre- and post-establishment periods indicate that the reserve has become more fragmented and less suitable for giant panda habitation. The rate of loss of high-quality habitat after the reserve's establishment was much higher than before the reserve was created, and the fragmentation of high-quality habitat became far more severe. After the creation of the reserve, rates of habitat loss and fragmentation inside the reserve unexpectedly increased to levels that were similar to or higher than those outside the reserve, in contrast to the situation before the reserve was created.     

亚热带典型森林凋落物及细根的生物量和碳储量研究

细根和地上凋落物分解和周转,是建模和预测土壤碳汇需要测量的2个关键生态过程,通过对亚热带典型常绿阔叶林、杉木、马尾松林和毛竹林110个样地内凋落物和细根的生物量和碳储量进行研究,分析了森林细根和地上凋落物的生物量和碳储量以及彼此之间的差异和相互关系。结果表明：杉木林凋落物生物量 （4415 ± 0390） t/hm2最大,毛竹林 （2918 ± 0310） t/hm2最小,且与其他森林差异显著;凋落物碳储量毛竹林 （1176 ± 0260） t/hm2最小,与其他森林碳储量差异显著,最大的是常绿阔叶林 (1725 ± 016) t/hm2;4种不同森林类型细根生物量和碳储量差异显著,同一森林类型不同土层活和死细根生物量差异显著;从活/死根值中可知,常绿阔叶林细根周转要比针叶林 (杉木、马尾松) 快。     

Atomically resolved single-walled carbon nanotube intramolecular junctions

Intramolecular junctions in single-walled carbon nanotubes are potentially ideal structures for building robust, molecular-scale electronics but have only been studied theoretically at the atomic level. Scanning tunneling microscopy was used to determine the atomic structure and electronic properties of such junctions in single-walled nanotube samples. Metal-semiconductor junctions are found to exhibit an electronically sharp interface without localized junction states, whereas a more diffuse interface and low-energy states are found in metal-metal junctions. Tight-binding calculations for models based on observed atomic structures show good agreement with spectroscopy and provide insight into the topological defects forming intramolecular junctions. These studies have important implications for applications of present materials and provide a means for assessing efforts designed to tailor intramolecular junctions for nanoelectronics.