公私合营(PPP)项目市场需求风险分担研究

对PPP项目市场需求风险的影响因素、分担偏好、参与者的管理能力等问题进行探讨,以实例提出PPP项目市场需求风险完全由政府承担、政府与私人投资者共同承担及私人投资者承担的三种模式。在此基础上提出风险分担中政府所应承担的责任,以及市场分担与项目竞争强度的关系等观点,以期为政府后续PPP项目市场需求风险的管理提供参考和借鉴。     

Seasonal variations and mass closure analysis of particulate matter in Hong Kong

The chemical characteristics of ambient particulate matters in urban and rural areas of Hong Kong were determined in this study. A monitoring program starting from November 2000 to February 2001 (winter) and June 2001 to August 2001 (summer) for PM10 and PM2.5 was performed at three monitoring stations in Hong Kong. Twenty-four-hour PM10 and PM2.5 samples were collected once every 6 days at two urban sites, PolyU and KT, and every 12 days at a background site, HT, with Hi-Vol samplers. High concentrations of OC, EC (except in PolyU), water-soluble ions and elements were observed in winter among the three sampling sites for PM10 and PM2.5 fractions. Seasonal variations were significant in background HT. Dilution effect due to the increase in mixing depth and precipitation in summer reduced the concentrations of particulate matters. Long-range transport could contribute to the higher concentrations of particulate matter in the winter. Chemical mass closure calculations were performed for PM10 and PM2.5 observed. Mass closure improved when separate factors (1.4 and 1.9 respectively) were used to convert water-soluble organic carbon (WSOC) and water-insoluble organic carbon (WINSOC) into corresponding organic masses. The urban sites showed high percentages of water-soluble ions in winter and high percentages of carbonaceous species in summer. Better results were obtained for the chemical mass closure analysis in winter than in summer. High temperature and solar radiation in summer increased the rate of the complex photochemical reaction in the atmosphere. Therefore the chemical mass closure analysis would underestimate the volatized species and secondary aerosols during summer.     

基于介尺度结构解聚-重组装的Beta分子筛的绿色合成及应用

Beta分子筛作为一种重要的催化材料,被广泛应用于石油化工、煤化工及环境保护等领域,但其常规的水热合成过程存在成本高、单釜产率低和废水排放量大等问题。本研究提出了一条基于天然矿物介尺度结构解聚-重组装的无溶剂绿色合成Beta分子筛的新路线,采用该路线所合成的Beta分子筛（Beta-Anhyd）含有丰富的介孔和大孔结构,且具有较商业Beta分子筛（Beta-Ref）更高的比表面积和更低的酸量,以其为载体,通过脱Al补Sn制备的Sn-Beta催化剂（Beta-Anhyd-Deal）在丙烷脱氢反应中表现出较参比催化剂（Beta-Ref-Deal）更加优异的催化性能。     

第二过渡周期金属单氧化物电子结构的DFT表征

文章采用九种密度泛函方法系统地研究了第二过渡周期金属单氧化物及其正负离子的键长,频率,电离能,电子亲和势及解离能。     

Copper‐Catalyzed Aerobic Formation of Unstable Sulfinyl Radicals for the Synthesis of Sulfinates and Thiosulfonates

Copper‐catalyzed aerobic coupling of thiols and alcohols affords sulfinates and thiosulfonates. These products are assumed to form via sulfinyl radicals which are not commonly found in oxidative coupling reactions of thiols. A reaction mechanism involving sulfinyl radicals is proposed, and mass and electron paramagnetic resonance (EPR) experimental results are provided.

     

Use of artificial neural network to evaluate the vibration mitigation performance of geofoam-filled trenches

Development activities in a city often generate ground vibration that can cause discomfort to the occupants in nearby buildings, disturbances to the activities undertaken in the buildings and possible damage to nearby structures. This ground vibration is caused by construction activities such as pile driving, ground compaction etc., and road and rail traffic. The use of trenches has been an effective way to mitigate the adverse effects of such ground vibration. The effectiveness of the trench depends on many parameters including the properties of the vibration source, soil medium and trench in-fill material, trench dimensions and the requirements of the receiver. The process of selecting an effective trench for vibration mitigation can therefore become complex due to the influence of a number of parameters and their wide range of values. This paper investigates the use of artificial neural network (ANN) as a smart and efficient tool to predict the effectiveness of geofoam-filled trenches to mitigate ground vibration. Towards this end, a database is developed from an extensive study on the effects of the controlling parameters through numerical simulations with a validated finite element (FE) model. At a certain distance from the vibration source, a geofoam-filled trench is introduced to evaluate the efficiency of vibration mitigation with changes in key parameters such as excitation frequency, amplitude of load, trench configuration (i.e. depth and width), soil shear wave velocity, soil density and damping ratio. These were selected as the input parameters for the ANN while amplitude reduction ratio and peak particle velocity (PPV) were considered as outputs. A multilayer feed forward network was used and trained with the Levenberg-Marquardt algorithm. Neural networks with different configurations were evaluated by comparing coefficient of determination (R²) and mean square error (MSE). The optimum architecture was then used to predict previous results, which revealed the accuracy and the effectiveness of the ANN approach. The findings of this study will provide useful information for vibration mitigation using geofoam-filed trenches.     

增进城市地区生物多样性——以新加坡模式为例

自 1963 年以来,新加坡开展实施了绿化计划,并经历了从“花园城市”到“花园中的亲生态城市”的演变。为了在新加坡实现生物多样性保护,国家公园局制定了自然保护蓝图,重点介绍该规划实施的关键是利用技术创新。新加坡城市生物多样性指数是一种评价生物多样性成效的自我评估工具,已在全球范围内的多个城市得到应用。     

Transcriptional Regulation of Programmed Hypertension by Melatonin: An Epigenetic Perspective

Melatonin is an endogenously produced indoleamine and secreted by the pineal gland. Melatonin has pleiotropic bioactivities and is involved in epigenetic regulation. Suboptimal conditions during maternal and perinatal phases can elicit epigenetic regulation of genes for nephrogenesis and reset physiological responses to develop programmed hypertension. This review discusses the early utility of melatonin to prevent programmed hypertension in later life by epigenetic regulation in the kidney, with an emphasis on: (1) the role of melatonin in epigenetic regulation; (2) the beneficial effects of melatonin on programmed hypertension; (3) epigenetic regulation of maternal melatonin therapy in different developmental windows of offspring kidneys analyzed by whole-genome RNA next-generation sequencing; and (4) current blocks in the application of melatonin in preventing programmed hypertension.     

Cytotoxic Effects of Dillapiole on Embryonic Development of Mouse Blastocysts in Vitro and in Vivo

We examined the cytotoxic effects of dillapiole, a phenylpropanoid with antileishmanial, anti-inflammatory, antifungal, and acaricidal activities, on the blastocyst stage of mouse embryos, subsequent embryonic attachment and outgrowth in vitro, and in vivo implantation via embryo transfer. Blastocysts treated with 2.5–10 μM dillapiole exhibited a significant increase in apoptosis and corresponding decrease in total cell number. Notably, the implantation success rates of blastocysts pretreated with dillapiole were lower than those of their control counterparts. Moreover, in vitro treatment with 2.5–10 μM dillapiole was associated with increased resorption of post-implantation embryos and decreased fetal weight. Our results collectively indicate that dillapiole induces apoptosis and retards early post-implantation development, both in vitro and in vivo. However, the extent to which this organic compound exerts teratogenic effects on early human development is not known at present. Further studies are required to establish effective protection strategies against the cytotoxic effects of dillapiole.     

FT-IR Microspectrometry Reveals the Variation of Membrane Polarizability due to Epigenomic Effect on Epithelial Ovarian Cancer

Ovarian cancer, as well as other cancers, is primarily caused by methylation at cytosines in CpG islands, but the current marker for ovarian cancer is low in sensitivity and failed in early-stage detection. Fourier transform infrared (FT-IR) spectroscopy is powerful in analysis of functional groups within molecules, and infrared microscopy illustrates the location of specific groups within single cells. In this study, we applied HPLC and FT-IR microspectrometry to study normal epithelial ovarian cell line immortalized ovarian surface epithelium (IOSE), two epithelial ovarian cell lines (A2780 and CP70) with distinct properties, and the effect of a cancer drug 5-aza-2''-deoxycytidine (5-aza) without labeling. Our results reveal that inhibition of methylation on cytosine with 5-aza initiates the protein expression. Furthermore, paraffin-adsorption kinetic study allows us to distinguish hypermethylated and hypomethyated cells, and this assay can be a potential diagnosis method for cancer screening.