新形势下中国与中亚油气合作面临的挑战和前景展望（增刊）

中亚地区油气资源丰富,中国与中亚国家的油气合作已近20年,合作成果丰硕。在油价持续低迷的情况下,中亚国家对能源策略和油气政策做出了相应调整。新形势下,中国与中亚油气合作面临着地缘政治形势更加复杂、大国博弈和竞争激烈、合作思路需要调整等多重挑战。在“一带一路”战略背景下,我国要全面推进与中亚国家的油气合作,并在此基础上进一步推动能源综合发展,实现与中亚国家的协同发展。     

本土文化在丹麦现代园林中的传承

本土文化是地域景观生成的重要来源。除历史文化之外,生成本土文化的元素还有其他的可能吗?20世纪丹麦园林的发展例证了农业景观和专业传统的可能。文中将从特别限定的历史文化、农业景观和专业传统三个方面,探讨本土文化在丹麦现代园林中的传承。     

城市更新概念下的棕地转变为绿地

简要回顾了棕地的背景和概念,以及其改造利用的主要原则。在当代城市更新的背景下,将棕地改造为绿地成了可持续利用土地的重要途径之一。分别以柏林萨基兰德自然公园和巴塞罗那泊布诺公园为例,讨论了在不同的城市更新条件下棕地转化为绿地的工作框架。     

Invertebrate mercury bioaccumulation in permanent, seasonal, and flooded rice wetlands within California's Central Valley

We examined methylmercury (MeHg) bioavailability in four of the most predominant wetland habitats in California's Central Valley agricultural region during the spring and summer: white rice, wild rice, permanent wetlands, and shallowly-flooded fallow fields. We sampled MeHg and total mercury (THg) concentrations in two aquatic macroinvertebrate taxa at the inlets, centers, and outlets of four replicated wetland habitats (8 wetlands total) during two time periods bounding the rice growing season and corresponding to flood-up and pre-harvest (96 total samples). In general, THg concentrations (mean ± standard error) in Notonectidae (Notonecta, back swimmers; 1.18 ± 0.08 µg g^− 1 dry weight [dw]) were higher than in Corixidae (Corisella, water boatmen; 0.89 ± 0.06 µg g^− 1 dw, MeHg: 0.74 ± 0.05 µg g^− 1 dw). MeHg concentrations were correlated with THg concentrations in Corixidae (R² = 0.80) and 88% of THg was in the MeHg form. Wetland habitat type had an important influence on THg concentrations in aquatic invertebrates, but this effect depended on the sampling time period and taxa. In particular, THg concentrations in Notonectidae, but not Corixidae, were higher in permanent wetlands than in white rice, wild rice, or shallowly-flooded fallow fields. THg concentrations in Notonectidae were higher at the end of the rice growing season than near the time of flood-up, whereas THg concentrations in Corixidae did not differ between time periods. The effect of wetland habitat type was more prevalent near the end of the rice growing season, when Notonectidae THg concentrations were highest in permanent wetlands. Additionally, invertebrate THg concentrations were higher at water outlets than at inlets of wetlands. Our results indicate that although invertebrate THg concentrations increased from the time of flood-up to draw-down of wetlands, temporarily flooded habitats such as white rice, wild rice, and shallowly-flooded fallow fields did not have higher THg or MeHg concentrations in invertebrates than permanent wetlands.     

浅谈变频器在中央空调系统节能改造中的运用

随着中国经济的快速发展,中央空调系统已在社会广泛应用,在为人们提供舒适的工作和生活环境的同时,中央空调系统也成为建筑的能耗大户。在全球推进低碳经济,节能减排的大趋势下,如何节能、高效地解决中央空调系统的节能减排问题,已经成为社会研究的热点。据国家能源局统计,我国建筑能耗约占全国总能耗的30%左右,而空调能耗又约占建筑总能耗的50%~65%,降低空调系统能耗对我国完成节能减排目标与推动建设为节约型社会具有非常重要的作用。     

港岛城市剖面

文章借用建筑学上的剖面概念,将其应用到城市尺度的形态分析和空间解读上。作者选取香港中环地区的中环至半山由自动扶梯系统覆盖的城市区域,作为诠释这一概念的具体案例。建筑剖面的传统意义被移植至城市剖面中,即在某一方向上剖切实体之后,通过观察剖切面上空间元素之间的关系,探寻彼此的内在结构,乃至这种城市结构空间背后的特殊历史过程和社会推力。香港岛的地理特征和100多年来城市化过程所形成的带状城市分布使得港岛具有剖面性格,而中环至半山的自动扶梯系统提供了一条重要的剖切线索。通过剖面方法解析,作者希望在城市形态学的分析方法上有新的突破。     

区域性中心城市CBD建设的动因及发展策略

结合中央商务区（CBD）的概念,从全球经济一体化的趋势和国家发展战略入手,阐述了大连CBD建设的背景,探讨了适合大连的CBD发展思路,提出了大连CBD建设的目标及策略,为国内其他城市CBD建设提供了指导。     

Combination of warm water and hydrogen peroxide to reduce the numbers of Salmonella Typhimurium and Listeria innocua on field salad (Valerianella locusta)

The optimal conditions of decontamination of field salad by treatment with warm water containing hydrogen peroxide were determined with the aid of a central composite design. It was the aim to improve the hygienic status while keeping the sensory quality at the highest level possible. Two series of experiments were performed to study the effects of the following parameters: temperature (45–50 °C), H₂O₂ (1–4%) and treatment time (60–210 s). In series 1 the effect on sensory properties and reduction of total aerobic counts was investigated. To determine sensory quality, treated samples stored at 4 °C for 7 days were subjected to evaluation by 15 panelists. Overall visual quality (OVQ), color, texture and odor correlated well with product acceptability (R²=0.934, 0.946, 0.945 and 0.956, respectively), and OVQ was the most sensitive criterion. An acceptability of 75% in OVQ was chosen as the limit and an acceptance area was defined to deduce permitted conditions for decontamination. Within that area a reduction of total counts by 2.64–3.22 and 1.9–3.48 log₁₀ cfu/g was achieved after treatment and storage at 4 °C for 7 days, respectively. In series 2 field salad was inoculated with Listeria innocua and Salmonella Typhimurium and it was observed that within the area of acceptability a reduction of the numbers of the challenge organisms by 1.27–3.26 and 0.79–3.05 log₁₀ cfu/g, respectively, was achieved immediately after treatment, and by 1.64–3.09 (L. innocua) and 1.1–2.63 log₁₀ cfu/g (S. Typhimurium) after storage. The initial decontaminating effect on L. innocua and S. Typhimurium was sustained or even increased after storage, when the salad was treated below 48.9 °C for more than 68 s. Three independent experiments confirmed the reliability of the models of the count reduction of L. innocua and S. Typhimurium.     

Assessment of iron bioavailability from twenty elite late‐maturing tropical maize varieties using an in vitro digestion/Caco‐2 cell model

An in vitro digestion/Caco‐2 cell model was used to assess iron bioavailability of twenty elite late‐maturing tropical maize varieties grown in three diverse agroecologies in West and Central Africa (WCA). Kernel‐iron concentration of the varieties, averaged across locations, varied from 19.2 to 24.4 mg kg^?1, while mean kernel‐zinc concentration ranged between 19.4 and 24.6 mg kg^?1. Significant differences in iron bioavailability were observed among varieties, but the environment had no significant effect. Mean bioavailable iron ranged between 14% below and 43% above the reference control variety, TZB‐SR. Variety DMR‐LSR‐Y with the highest concentrations of kernel‐iron and ‐zinc of 24–25 mg kg^?1 across the three locations had a similar quantity of bioavailable iron as the reference control, TZB‐SR. In the long run this variety could be potentially effective in reducing iron deficiency because of its high kernel‐iron. The most promising varieties were Mid‐altitude STR synthetic and ACR91SUWAN‐1‐SRC1. They had kernel‐iron and ‐zinc levels of 22–24 mg kg^?1 and bioavailable iron 24–36% higher than the reference control, TZB‐SR. Additional research is necessary to determine if the increases in kernel‐iron concentration and bioavailable iron observed in this study can significantly improve the iron status of individuals in WCA at risk for iron deficiency. Copyright © 2004 Society of Chemical Industry     

青藏直流投运后藏中电网稳定特性研究

藏中电网规模较小,网架结构相对较弱,青藏直流联网工程投运后给藏中电网的安全稳定运行带来诸多挑战,交直流系统稳定问题突出。从联网工程投运前藏中电网的电源特性、大机小网等固有特性出发,结合青藏直流联网以来青藏直流以及藏中电网运行中存在的各种稳定问题,深入分析了青藏直流投运后藏中电网的电源特性变化、稳定特性转化、虎曲线功率送出、直流换相失败、以及交直流影响等安全稳定问题。同时针对西藏电网的运行特性,分析并指出了青藏直流几个重要而特殊的安全稳定运行特性。