Dinuclear zinc-catalyzed asymmetric Friedel-Crafts alkylation/cyclization of 3-aminophenols with α,α-dicyanoolefins.

An enantioselective Friedel-Crafts alkylation/cyclization tandem reaction of 3-aminophenols with α,α-dicyanoolefins has been performed successfully using a chiral dinuclear zinc catalyst, leading to a range of chiral 2-amino-4H-chromenes (up to 98% yield and >99% ee). To the best of our knowledge, this is the first asymmetric example of the dinuclear zinc-catalysed functionalization of aromatic C(sp2)-H bonds.

Direct Asymmetric α-Selective Mannich Reaction of ß,γ-Unsaturated Ketones with Cyclic α-Imino Ester: Divergent Synthesis of Cyclocanaline and Tetrahydro Pyridazinone Derivatives.

The first regio-, diastereo-, and enantioselective direct Mannich reaction of ß,γ,-unsaturated ketones with benzoxazinone cyclic imines was enabled by Lewis acid/Brønsted base cooperative catalysis. The dinuclear zinc complex catalyzed the reaction of a broad range of ß,γ-unsaturated ketones to proceed at the α-site exclusively, leading to corresponding adducts with two consecutive tertiary carbon stereocenters in diastereomeric ratios of up to >20:1 and enantioselectivities generally in the 90-99 % ee range. These products were used as general intermediates in the synthesis of multisubstituted cyclocanalines, tetrahydro pyridazinones, and 4H-furo[2,3-b][1,4]benzoxazine derivatives.

Characteristics of carbon dioxide emissions in response to local development: Empirical explanation of Zipf's law in Chinese cities.

Carbon emissions and city development are currently two major areas of interest worldwide. With the continuous development of cities, the problem of carbon emissions has received substantial attention. Analyzing the relationship between carbon emissions and city development is key to building low-carbon cities. This paper selects the revised Zipf's law to explore diverse carbon emission characteristics in different stages of city development and tries to verify the balance of city development and the rationality of key emitting sectors in China, thus filling a gap in this domain. Based on the analysis of different emitting sectors and diverse city categories, several discoveries are made. First, nearly 80% of Chinese cities have reached the ideal state of Zipf's law between carbon dioxide (CO2) emissions and city development. In general, carbon emissions and city development are basically matched at the present stage. Second, in cities, the carbon emissions of the agricultural and industrial processes sectors are relatively balanced and stable with the city development. In addition, only the traffic sector is in the stage of intensive development. Other sectors (industrial energy, rural household, urban household, services, and indirect emissions) need to be further optimized. Third, CO2 emissions in other type of cities are basically matched with the city development. Industrial cities, megalopolises and metropolises are in the stage of intensive development, while cities of other types (service-oriented cities and small-medium cities) need to be further optimized. Fourth, corresponding measures, such as adjusting energy and industrial structure, optimizing resource allocation, and promoting intensive production, need to be taken to optimize carbon emissions in cities of different types and in different emitting sectors. Our study provides a particular theoretical basis and practical value, for China and other countries in similar situations, to coordinate the matching correlation between city development and carbon emissions in the future.

Land use-based landscape planning and restoration in mine closure areas.

Landscape planning and restoration in mine closure areas is not only an inevitable choice to sustain mining areas but also an important path to maximize landscape resources and to improve ecological function in mine closure areas. The analysis of the present mine development shows that many mines are unavoidably facing closures in China. This paper analyzes the periodic impact of mining activities on landscapes and then proposes planning concepts and principles. According to the landscape characteristics in mine closure areas, this paper classifies available landscape resources in mine closure areas into the landscape for restoration, for limited restoration and for protection, and then summarizes directions for their uses. This paper establishes the framework of spatial control planning and design of landscape elements from "macro control, medium allocation and micro optimization" for the purpose of managing and using this kind of special landscape resources. Finally, this paper applies the theories and methods to a case study in Wu'an from two aspects: the construction of a sustainable land-use pattern on a large scale and the optimized allocation of typical mine landscape resources on a small scale.

Loop-mediated isothermal amplification method for rapid detection of the toxic dinoflagellate Alexandrium, which causes algal blooms and poisoning of shellfish.

The marine dinoflagellate genus Alexandrium includes a number of species that produce potent neurotoxins responsible for paralytic shellfish poisoning, which in humans may cause muscular paralysis, neurological symptoms and, in extreme cases, death. Because of the genetic diversity of different genera and species, molecular tools may help to detect the presence of target microorganisms in marine field samples. Here we employed a loop-mediated isothermal amplification (LAMP) method for the rapid and simple detection of toxic Alexandrium species. A set of four primers were designed based upon the conserved region of the 5.8S rRNA gene of members of the genus Alexandrium. Using this detection system, toxic Alexandrium genes were amplified and visualized as a ladder-like pattern of bands on agarose gels under isothermal condition within 60 min. The LAMP amplicons were also directly visualized by eye in the reaction tube by the addition of SYBR Green I. This LAMP assay was 10-fold more sensitive than a conventional PCR method with a detection limit of 5 cells per tube when targeting DNA from Alexandrium minutum. The LAMP assay reported here indicates the potential usefulness of the technique as a valuable simple, rapid alternative procedure for the detection of target toxic Alexandrium species during coastal water monitoring.

[FTIR analysis of the alcohol solution treated by high voltage electric field].

This paper studied the FTIR spectrum change of alcohol-water system after treated by high voltage electric field (2.0 kV.cm-1, 50 Hz). 4 kinds of systems were studied: pure water, 10% and 50% alcohol water solution and pure alcohol. Results showed that the position of nu (OH) in FTIR spectrum reflect the amount of hydrogen bonds in the alcohol-water system; when the solution treated by 1-30 min, the hydrogen bonds increased first and then decreased a lot. When the 50% alcohol solution and pure alcohol were treated more than 30 min by 2.0 kV.cm-1 electric field, peaks of nu (c-o) and nu (OH)(H2O) appeared in the spectrum. This indicated that alcohol might be oxidized by external physical field force and aldehyde and ester were formed. Test for the treated samples 7 days later found the FTIR spectra were almost the same. Some mechanisms were deduced.