An ecological approach to landscape planning using geographic information system technology

This paper describes two research programs that are aimed at developing ecologically-based landscape planning models. The first of these models was developed as part of a more comprehensive landscape planning research program at the University of Massachusetts. The second is an on-going program in forest land planning at the University of Vermont. In addition to an emphasis on ecological values, both projects make extensive use of computerized geographic information systems (GIS) for data storage, analysis and display. The emphasis has been to develop a synthesis of planning procedures, ecological theories and quantitative techniques. Both research efforts were guided by a three-part methodological framework adapted from the work of Eugene Odum. The Massachusetts work generated a two-part classification system. The first part of the classification uses the statistical technique of discriminant analysis to place land uses into five groups, each having similar ecological characteristics. The second part of the classification is based on the physical and environmental characteristics of a site. The biological and denudational potentials of a site are determined from soil characteristics and slope. A comparison of the two classification schemes was made to determine ecological compatibility. The procedures were applied to two communities in Western Massachusetts. The Vermont study was aimed at integrating ecological values into forest land management and planning processes. The research utilized soils and topographic information in the development of an ecologically based forest land suitability model. Forest site index and soil erosion potential were determined using data stored in a computerized geographic information system. Forest site index estimates were made by utilizing an existing, well documented soil-site index regression equation applicable to the Green Mountains of Vermont. Soil erosion potential estimates were made by combining a soil erodability factor (K) with slope. The site index and soil erosion estimates were combined to produce land suitability classes for resource protection, forest management, multiple-use and trade-off. The procedure was applied in the Mad River Valley in Central Vermont. Both the Massachusetts and the Vermont studies are seen as significant contributions toward the integration of ecological factors into processes for landscape planning and resource management.     

Boronic Acid‐Catalyzed Selective Oxidation of 1,2‐Diols to α‐Hydroxy Ketones in Water

The activation of 1,2‐diols through formation of boronate esters was found to enhance the selective oxidation of 1,2‐diols to their corresponding α‐hydroxy ketones in aqueous medium. The oxidation step was accomplished using dibromoisocyanuric acid (DBI) as a terminal chemical oxidant or an electrochemical process. The electrochemical process was based on the use of platinum electrodes, methylboronic acid [MeB(OH)₂] as a catalyst and bromide ion as a mediator. Electro‐generated OH⁻ ions (EGB) at the cathode acted as a base and “Br⁺” ion generated at the anode acted as an oxidant. Various cyclic and acyclic 1,2‐diols as substrates were selectively oxidized to the corresponding α‐hydroxy ketones via their boronate esters by the two oxidative methods in good to excellent yields.

     

魏森霍夫

魏森霍夫住宅展作为20世纪20年代现代主义建筑的代表在建筑历史上占有很重要的地位,但其真正的意义是否有那么重要?德国建筑理论家尤利乌斯·波泽纳(Julius Posener)对此有自己的观点。他认为魏森霍夫最重要的作用是产生新的建筑形式,并不是强调功能。在文中,他解释了为什么在魏森霍夫中密斯、柯布西耶和奥德的设计被公认为最重要的建筑。最后,他借对穆特休斯的观点表达出对魏森霍夫的一些质疑。     

Visualizing resonance energy transfer in supramolecular surface patterns of β-CD-functionalized quantum dot hosts and organic dye guests by fluorescence lifetime imaging

Detection of an analyte via supramolecular host-guest binding and quantum dot (QD)-based fluorescence resonance energy transfer (FRET) signal transduction mechanism is demonstrated. Surface patterns consisting of CdSe/ZnS QDs functionalized at their periphery with β-cyclodextrin (β-CD) were obtained by immobilization of the QDs from solution onto glass substrates patterned with adamantyl-terminated poly(propylene imine) dendrimeric "glue." Subsequent formation of host-guest complexes between vacant β-CD on the QD surface and an adamantyl-functionalized lissamine rhodamine resulting in FRET was confirmed by fluorescence microscopy, spectroscopy, and fluorescence lifetime imaging microscopy (FLIM).     

A DNA Segregation Module for Synthetic Cells

The bottom-up construction of an artificial cell requires the realization of synthetic cell division. Significant progress has been made toward reliable compartment division, yet mechanisms to segregate the DNA-encoded informational content are still in their infancy. Herein, droplets of DNA Y-motifs are formed by liquid–liquid phase separation. DNA droplet segregation is obtained by cleaving the linking component between two populations of DNA Y-motifs. In addition to enzymatic cleavage, photolabile sites are introduced for spatio-temporally controlled DNA segregation in bulk as well as in cell-sized water-in-oil droplets and giant unilamellar lipid vesicles (GUVs). Notably, the segregation process is slower in confinement than in bulk. The ionic strength of the solution and the nucleobase sequences are employed to regulate the segregation dynamics. The experimental results are corroborated in a lattice-based theoretical model which mimics the interactions between the DNA Y-motif populations. Altogether, engineered DNA droplets, reconstituted in GUVs, can represent a strategy toward a DNA segregation module within bottom-up assembled synthetic cells.