努尔苏丹2030年规划(2)——策略性干预

本文介绍了英国空间句法公司于2020年为哈萨克斯坦首都努尔苏丹市制定的规划设计方案,着重介绍了为实现2030年规划愿景所需要的战略性设计干预内容。具体包括:(1)宜居性,改善关键社会基础设施的可达性;(2)可持续性,通过翻新现有建筑物来减少能源消耗;(3)健康,鼓励步行与非机动车出行,改善医疗、公共交通和体育设施的易得性;减少城市对汽车的依赖,并创建舒适、有吸引力的城市空间网络。     

The Use of Porous Palladium(II)‐polyimine in Cooperatively‐ catalyzed Highly Enantioselective Cascade Transformations

Porous organic polymers have prospects as functional substrates for catalysis, with quite different molecular properties from inorganic substrates. Here we disclose for the first time that porous palladium(II)‐polyimines are excellent catalysts for cooperatively catalyzed and enantioselective cascade reactions. In synergy with a chiral amine co‐catalyst, polysubstituted cyclopentenes and spirocyclic oxindoles, including the all‐carbon quaternary stereocenter, were synthesized in high yields. High diastereo‐ and enantioselectivities were achieved for these dynamic kinetic asymmetric transformations (DYKAT) of enals with propargylic nucleophiles.

     

Performance of carbon-supported PtPd as catalyst for hydrogen oxidation in the anodes of proton exchange membrane fuel cells

In this work, the replacement of platinum by palladium in carbon-supported catalysts as anodes for hydrogen oxidation reaction (HOR), in proton exchange membrane fuel cells (PEMFCs), has been studied. Anodes with carbon-supported Pt, Pd, and equiatomic Pt:Pd, with various Nafion^® contents, were prepared and tested in H₂|O₂ (air) PEMFCs fed with pure or CO-contaminated hydrogen. An electrochemical study of the prepared anodes has been carried out in situ, in membrane electrode assemblies, by cyclic voltammetry and CO electrooxidation voltammetry. The analyses of the corresponding voltammograms indicate that the anode composition influences the cell performance. Single cell experiments have shown that platinum could be replaced, at least partially, saving cost with still good performance, by palladium in the hydrogen diffusion anodes of PEMFCs. The performance of the PtPd catalyst fed with CO-contaminated H₂ used in this work is comparable to Pt, thus justifying further work varying the CO concentration in the H₂ fuel to assert its CO tolerance and to study the effect of the Pt:Pd atomic ratio.     

Extrapolation of a predictive model for growth of a low inoculum size of Salmonella Typhimurium DT104 on chicken skin to higher inoculum sizes

Validation of model predictions for independent variables not included during model development can save time and money by identifying conditions for which new models are not needed. A single strain of Salmonella Typhimurium DT104 was used to develop a general regression neural network (GRNN) model for growth of a low inoculum size (0.9 log) on chicken skin with native microflora as a function of time (0 to 8 h) and temperature (20 to 45°C). The ability of the GRNN model to predict growth of higher inoculum sizes (2, 3, or 4.1 log) was evaluated. When the proportion of residuals in an acceptable prediction zone (pAPZ) from -1 log (fail-safe) to 0.5 log (fail-dangerous) was ≥0.7, the GRNN model was classified as providing acceptable predictions of the test data. The pAPZ for dependent data was 0.93 and for independent data for interpolation was 0.88. The pAPZs for extrapolation to higher inoculum sizes of 2, 3, or 4.1 log were 0.92, 0.73, and 0.77, respectively. However, residual plots indicated local prediction problems with pAPZs of < 0.7 for an inoculum size of 3 log at 30, 35, and 40°C and for an inoculum size of 4.1 log at 35 and 40°C where predictions were fail-dangerous, indicating faster growth at higher inoculum sizes. The model provided valid predictions of Salmonella Typhimurium DT104 growth on chicken skin from inoculum sizes of 0.9 and 2 log at all temperatures investigated and from inoculum sizes of 3 and 4.1 log at some but not all temperatures investigated. Thus, the model can be improved by including inoculum size as an independent variable.     

Single-Phase Inverter Synchronized to the Grid by Linear Kalman Filter in Microgrids

This paper presents the analysis and implementation of a synchronizer to the grid using a linear Kalman filter. The synchronizer is used in a single-phase inverter, which is applied in an environment of microgrids. The inverter converts the energy that comes from renewable energy sources （photovoltaic, wind, fuel cell, etc.）. The main objective of obtaining the phase of the grid is to achieve a power factor close to unity in the inverter. For this reason it is vital that the phase difference between the synchronizer and the grid zero. To obtain synchronizer algorithm using LKF （linear Kalman filter） is necessary to know the EKF （extended Kalman filter）. This allows to analyze the operation of the filter, which allows to reach reduce linear Kalman filter or also known as simplified Kalman filter. It is necessary to generate an orthogonal signal in order to obtain a stationary reference frame from a single-phase grid because the linear Kalman filter works with a stationary reference frame. Orthogonal signal is created with an all-pass filter.     

Detection of Salmonella Senftenberg associated with high saline environments in mussel processing facilities

A contamination by Salmonella Senftenberg in frozen mussels was detected in 1998 during a routine analytical surveillance. From June 1998 to December 2001, a total of 3,410 samples of steamed frozen mussels and items related to their manufacture were analyzed for the presence of Salmonella. Salmonella Senftenberg was isolated in 573 (16.8%) samples, and no other serovar was detected. The contamination episodes extended for several months. Salmonella Senftenberg colonies from the first contamination events showed a rugose morphology on agar with a shiny crystalline layer and limited colony formation on microbiological media. These contaminations were mainly associated with brine (300 g of NaCl per liter), while the live molluscs that were being processed were free of Salmonella. When the brine contaminations were nearly controlled, new episodes were detected that were associated with live mussels. In the new episodes, colonies showed the typical characteristics of Salmonella and normal growth on agar. Salmonella Senftenberg presented a high resistance to unfavorable environments and showed a preference for clean environments. While Salmonella Senftenberg could be isolated from mussels after steam treatment, it could not survive after immersion in water at 80 degrees C for 1 min. This fact was used to develop a process to remove contamination from products, minimizing the health risk associated with frozen mussel consumption. The general incidence of Salmonella Senftenberg in facilities and mussels was reduced from 31.2% in 1998 to 2.5% in 2001. During this study, no cases of illness from consumption of frozen mussels were reported, indicating a possible lack of virulence of Salmonella Senftenberg in these contamination events.     

Phytoremediation of mercury and organomercurials in chloroplast transgenic plants: enhanced root uptake, translocation to shoots, and volatilization

Transgenic tobacco plants engineered with bacterial merA and merB genes via the chloroplast genome were investigated to study the uptake, translocation of different forms of mercury (Hg) from roots to shoots, and their volatilization. Untransformed plants, regardless of the form of Hg supplied, reached a saturation point at 200 microM of phenylmercuric acetate (PMA) or HgCl2, accumulating Hg concentrations up to 500 microg g(-1) with significant reduction in growth. In contrast, chloroplast transgenic lines continued to grow well with Hg concentrations in root tissues up to 2000 microg g(-1). Chloroplasttransgenic lines accumulated both the organic and inorganic Hg forms to levels surpassing the concentrations found in the soil. The organic-Hg form was absorbed and translocated more efficiently than the inorganic-Hg form in transgenic lines, whereas no such difference was observed in untransformed plants. Chloroplast-transgenic lines showed about 100-fold increase in the efficiency of Hg accumulation in shoots compared to untransformed plants. This is the first report of such high levels of Hg accumulation in green leaves or tissues. Transgenic plants attained a maximum rate of elemental-Hg volatilization in two days when supplied with PMA and in three days when supplied with inorganic-Hg, attaining complete volatilization within a week. The combined expression of merAB via the chloroplast genome enhanced conversion of Hg2+ into Hg,0 conferred tolerance by rapid volatilization and increased uptake of different forms of mercury, surpassing the concentrations found in the soil. These investigations provide novel insights for improvement of plant tolerance and detoxification of mercury.     

A bio-economic ‘war game’ model to simulate plant disease incursions and test response strategies at the landscape scale

Loss of area freedom from invasive alien species can have serious food security implications and place huge responsibility on incursion response managers. They make critical decisions despite profound uncertainty surrounding invasion ecology, surveillance and control technology effectiveness and human behaviour. We propose a spatially-explicit model that can aid response managers in devising and testing management strategies in a virtual world where the costs of failure are negligible. We apply the model in a group-based decision setting in which participants practise responding to fictional disease incursions in a pome fruit production area in Australia. Using the model, the response management group was able to develop mutually satisfactory rules of thumb for the use of quarantine and destruction zones and for when to withdraw resources from eradication efforts.