Benzyl 3-dehydr­oxy-1,2,5-oxadiazolo[3′,4′:2,3]oleanolate

The title compound, C37H50N2O3, is a benzyl ester derivative of oleanolic acid, a penta­cyclic triterpene, with a five-membered oxadiazole ring fused to the ring A. The triterpene A and C rings adopt slightly distorted half-chair conformations, whereas the remaining three six-membered rings are in chair forms

Observed trends of heating and cooling degree-days in Xinjiang Province, China

Global warming has the potential to impact various aspects of human society such as agriculture, construction, transportation, water resources management, power generation, and phenology. The impact on energy, especially energy consumption for heating and cooling of buildings, is very important. These influences are different in terms of space and time due to spatial and temporal variations of temperature. In this study, daily data of minimum and maximum temperature of 51 stations for 1959-2004 were used to detect annual and seasonal variations of heating and cooling degree-days in Xinjiang, China, by using the Mann-Kendall trend test and linear regression techniques. The results indicate that: (1) taking 18A degrees C as the base temperature, annual mean heating degree-days (HDD) ranged between 2,700 and 7,973A degrees C, and annual mean cooling degree-days (CDD) (the base temperature is 24A degrees C) ranged between 0.4 and 792A degrees C. CDDs are relatively low in Xinjiang; (2) autumn, winter, and annual HDDs show significant decreasing trends. Annual CDD at 23 out of 51 stations present significant increasing trends, while no remarkable positive trends can be observed at the other stations; and (3) with respect to spatial variations, Xinjiang was characterized by significant decreasing annual, winter, and autumn HDDs, and it was particularly true for the northern Xinjiang. The annual and summer CDDs in the western parts of northern Xinjiang (the edges of the Tarim Basin and the Turpan-Hami Basin) were characterized by significant increasing trends. However, no fixed spatial patterns can be identified in the variations of annual and summer CDDs. The results of this study could be useful for energy management in Xinjiang and are also helpful for better understanding of impacts of global warming on energy consumption in other countries of the world

1,2,5-Oxadiazolo[3,4-b]glycyrrhetinic acid

The title compound [systematic name: 11-oxo-2,3-(oxydinitrilo)olean-12-en-29-oic acid], C30H42N2O4, contains a linear array of five six-membered rings and a five-membered heterocyclic ring. The C ring, containing an α,β-unsaturated ketone, has a slightly distorted half-chair conformation, as does the A ring, with N—C—C angles 125.3 (5), 111.2 (4), 124.9 (5) and 109.2 (5)°, while the other three six-membered rings adopt chair conformations. The enantiomer has been assigned by reference to unchanging chiral centres in the synthetic procedure. An intramolecular C—H...O interaction is present. In the crystal structure, intermolecular O—H...O hydrogen bonds link the molecules

Variations and trends of the freezing and thawing index along the Qinghai-Xizang Railway for 1966-2004

Annual freezing and thawing index of 7 meteorological stations along the Qinghai-Xizang Railway were calculated based on daily maximum and minimum temperature records for 1966-2004. Trends of annual freezing and thawing index were analyzed using the Mann-Kendall test and a simple linear regression method. The results show that: 1) The mean annual freezing indices range from 95 to 2300 degrees C.d and the mean annual thawing indices range from 630 to 3250 degrees C.d. The mean annual freezing index of the 7 stations exhibited decreasing trends with decreasing rate of -16.6- -59.1 degrees C center dot d/10a. The mean annual thawing index of these 7 stations showed increasing trends with the related decreasing rate is 19.83-45.6 degrees C center dot d/10a. 2) The MK trend test indicated the significant decreasing trends (significant at < 0.05 significant level) in the annual freezing index for most stations except for Golmud. The significant increasing trends can be observed in the annual thawing index for 4 stations except Golmud and Tuotuohe. Golmud was the only station with no trends in both annual freezing and annual thawing index

Recent and future climate change in northwest china

As a consequence of global warming and an enhanced water cycle, the climate changed in northwest China, most notably in the Xinjiang area in the year 1987. Precipitation, glacial melt water and river runoff and air temperature increased continuously during the last decades, as did also the water level of inland lakes and the frequency of flood disasters. As a result, the vegetation cover is improved, number of days with sand-dust storms reduced. From the end of the 19th century to the 1970s, the climate was warm and dry, and then changed to warm and wet. The effects on northwest China can be classified into three classes by using the relation between precipitation and evaporation increase. If precipitation increases more than evaporation, runoff increases and lake water levels rise. We identify regions with: (1) notable change, (2) slight change and (3) no change. The future climate for doubled CO2 concentration is simulated in a nested approach with the regional climate model-RegCM2. The annual temperature will increase by 2.7 degrees C and annual precipitation by 25%. The cooling effect of aerosols and natural factors will reduce this increase to 2.0 degrees C and 19% of precipitation. As a consequence, annual runoff may increase by more than 10%