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An inverse-electron-demand oxa-Diels-Alder reaction of 5-alkenyl thiazolones with β,γ-unsaturated carbonyl compounds enabled by quinine thiourea was studied, which allows the enantioselective synthesis of a broad range of highly functionalized pyranthiazoles bearing three continuous stereocenters. This protocol is adaptable to a wide scope of substrates and has great potential for scale-up synthesis and facile transformation.

A protocol for the chemically divergent synthesis of β-lactams and α-amino acid derivatives with isothiourea (ITU) catalysis by switching solvents was developed. The stereospecific Mannich reaction occurring between imine and C(1)-ammonium enolate generated zwitterionic intermediates, which underwent intramolecular lactamization and afforded β-lactam derivatives when DCM and CH

We have developed a metal-free, visible-light driven chiral phosphoric acid catalyzed asymmetric intermolecular, three-component radical-initiated dicarbofunctionalization and oxytrifluoromethylation of enamines.

Using diverse carbon-centered radical precursors and electron-rich (hetero)aromatics and alcohols as nucleophiles, a visible-light driven chiral phosphoric acid (CPA) catalyzed asymmetric intermolecular, three-component radical-initiated dicarbofunctionalization and oxytrifluoromethylation of enamines was developed, which provides a straightforward access to chiral arylmethylamines, aza-hemiacetals and γ-amino acid derivatives with excellent enantioselectivity. As far as we know, this is the first example of constructing a chiral C-O bond using simple alcohols

Black carbon (BC) has a significant impact on air quality and atmospheric light absorption due to its unique physical properties. In this study, a ten-wavelength black carbon monitor was used to measure BC concentrations continuously during winter in urban Beijing. A comparison of BC concentrations was carried out between the ten-wavelength black carbon monitor and a multi-angle absorption photometer (MAAP) and a thermal optical transmission method carbon analyzer. The results showed significant correlations between BC measured by the MAAP, the thermal optical transmission method carbon analyzer and BC measured at the 660 nm wavelength using the ten-wavelength black carbon monitor. Obvious differences in BC concentrations were recorded at the different wavelength ranges. The BC concentrations observed in the visible ranges, near-infrared ranges and near-ultraviolet ranges were on average 3.1, 2.6, and 4.6 μg m−3, respectively. The differences between the absorption coefficient of BC370 nm and BC880 nm increased with the enhancement of OC:TC (ratio of organic carbon to total carbon) and PM2.5, indicating that organic matter had strong light absorption at near-ultraviolet wavelength. BC concentrations had clear diurnal variations with maxima at 0300 and minima at 1400 (Local time). In addition, potential contribution source areas of BC were also analyzed. This is the first time that BC measurements have been conducted using the ten-wavelength BC monitor, which provided more information of BC at different wavelengths compared to other methods.

A directing group promoting the cyclopropanation of indoles with 2-furylcarbenoids has been developed. These carbenes are derived from enynones and cost-effective ZnI2 is employed as the catalyst for the efficient construction of various polycyclic compounds under mild reaction conditions.

A series of novel biselectrophilic β,γ-unsaturated α-ketoesters were designed and synthesized from rhodanine. Under the catalysis of chiral squaramides, the enantioselective [3 + 3] annulation reaction of these novel ketoesters with pyrazolones was developed. This reaction offers an efficient method for the synthesis of chiral 2'-thioxo-5,6-dihydrospiro[pyrano[2,3

In order to study the concentration and distribution characteristics of water-soluble inorganic ions in aerosol particles of the Beibei district of Chongqing, aerosol samples were collected with an Andersen cascade impactor between March 2014 and February 2015. Water-soluble inorganic ions, including Na

To study the pollution characteristics of atmospheric carbon aerosols, aerosol samples were collected via a cascade impactor (Andersen) from March 2014 to February 2015 in Beibei District, Chongqing. Organic carbon (OC) and element carbon (EC) were detected using a DRI 2001A carbon analyzer. The results showed that the annual average concentrations of OC and EC in PM

Most of the methods need to build a sophisticated classifier to detect the image tamper which leads the lower detection efficiency. For this problem, we propose a method based on artifacts detection techniques in the process produces of CFA, which includes one based on CFA pattern number estimation and the other noise analysis based on CFA. The techniques are based on computing a single feature and a simple threshold based on classifier, determine whether the mosaic artifacts of the CFA was changed. The experimental results show that, the proposed approach has higher performance.

Accurate measurement of organic carbon (OC) and elemental carbon (EC) in atmospheric fine particulate is an important scientific basis for studying the formation and source apportionment of carbonaceous aerosol. The selection of different analysis programs will lead to difference in the OC and EC concentrations, and further result in the misjudgment of the results. The OC and EC concentrations observed using three temperature protocols including RT-Quartz ( R) , NIOSH 5040 (N) and Fast-TC (F) were compared and analyzed in combination with the degree of air pollution in Beijing. The results showed that there was no significant difference in the TC (TC = OC + EC), OC and EC concentrations observed using R, N and F protocols and certain deviation was found among the TC (TC = OC + EC) , OC and EC concentrations. For TC, the results observed using R protocol were 5% lower than those using N protocol; hut 1% higher than those using F protocol. For OC, the results obtained using R were 9% lower than those using N protocol and 1% higher than those using F protocol. For EC, the results obtained using R were 20% higher than those using N protocol and 11% lower than those using F protocol. The variation coefficients for TC, OC and EC obtained based on R protocol were less than the other two temperature protocols under different air quality degrees. The slopes of regression curves of TC, OC and EC between on-line analysis using R protocol and off-line analysis were 1.21,1. 14 and 1.35, respectively. The correlation coefficients of TC, OC and EC were 0.99, 0.99 and 0.98, respectively. In contrast with the Black carbon ( BC) concentrations monitored by multi-angle absorption spectrophotometer (MAAP), the EC concentrations measured by on-line OC/EC analyzer using R protocol were obviously lower. When the BC concentrations were less than or equal to 8 gg*m3, the EC/BC ratio was 0.39. While the EC/BC ratio was 0.88, when the BC concentrations were greater than 8 ggm3. The variation trends of EC and BC concentrations were similar, while systematic error existed between the results obtained using those two instruments.

The closed hot precision forging process of a bevel gear with large cone angle was studied. According to the structure features of the bevel gear, two types of relief forging processes were proposed. First, simulations based on thermal-mechanical coupling finite element model were performed with Deform3D. Then the corresponding experiments were conducted and the results perfectly matched the simulation results. The advantages and deficiencies of two processes were discussed and a reliable basis for selecting the optimal process was proposed.

The production method of a driving axles used in gearbox is presented in this paper. A five-stage cold extrusion technology for forming the driving axle was made. First, simulations based on thermal-mechanical coupling finite element model were performed with Deform_2D. During the forming process, the concave appeared at the shaft end. And its formation mechanism was studied. Then the forming rules were obtained. Corresponding experiments were carried out and quality forging was achieved. Simulation and experimental results both indicate that the five-stage cold extrusion technology was feasible.

It is not optimistic about current air quality in Nanjing northern suburb, an area with the agglomeration of heavy industry such as steel-making and petrochemical industry. Measurement of ozone and its precursors conducted from May 18th to August 31st, with the Meteorological data recorded simultaneously, were analyzed to characterize the local photochemical pollution in summertime. The results showed that the average volume fraction of ozone (O3), nitrogen oxide (NO(x)) and volatile organic compounds (VOCs) in Nanjing northern suburb was about (32.01 ± 15.20) x 10(-9), (21.50 ± 14.02) x 10(-9) and (33.16 ± 25.20) x 10(-9), respectively, and carbon monoxide (CO) was (0.66 ± 0.44) x 10(-6). For O3, the maximum value reached 146.42 x 10(-9), exceeding the National Ambient Air Quality Standard II by a rate of 14.1%. The background level of O3, NO(x), VOCs and CO were estimated to be (5.71 ± 2.51) x 10(-9), (12.20 ± 0.36) x 10(-9), (22.44 ± 0.38) x 10(-9) and (0.28 ± 0.01) x 10(-6), respectively, from the frequency distribution of their hourly averaged volume fraction. Pollutants were significantly affected by local emission sources near the site. When affected by the southwest wind with the speed of 2-3 m x s(-1), active species of VOCs were easy to reach high level, accompanied by an increased concentration of O3; Under the influence of easterly winds, NO(x), CO and VOCs, mainly emitted from industrial sources and traffic sources, were prone to reach high level. The regulation and control measures were taken on industrial production and some vehicles during the Nanjing Asian Youth Games, but the concentration of O3 was not significantly reduced, and there were 4 days exceeding the National Ambient Air Quality Standard II.

In order to study the composition and distribution of VOCs (Volatile Organic Compounds) in the atmosphere in the urban area of Beibei district, Chongqing, atmospheric samples were collected from March 2012 to February 2013 with special stainless steel cylinders, and analyzed with a three-stage preconcentration method coupled with GC-MS. 78 species of VOCs were detected in this study, of which there were 25 species of alkanes, 15 species of olefins, 28 species of aromatic hydrocarbons and 10 species of halogenated hydrocarbons. The results showed that the top seven species of VOCs according to the order of annual average concentration in the atmosphere of Beibei were: Dichloromethane (3. 08 x 10(-9) ) , Benzene (2. 09 x 10-9) , Isopentane (1. 85 x 10 -9) , Toluene (1. 51 x 10(-9)) , Propane (1. 51 x 10(-9)), m/p-xylene (1.43 x 10(-9)) and Styrene (1. 39 x 10-9). The concentration of TVOCs (Total Volatile Organic Compounds) in the atmosphere of Beibei was 33. 89 x 10 -9 during the measuring period, and the seasonal variation was obvious with the order of spring (42. 57 x 10 -9)autumn (33.89 x 10-9)winter (31.91 x 10 -9)summer (27.04 x 10(-9)). In the composition of TVOCs, alkanes and aromatic hydrocarbons provided the largest contribution to TVOCs (31.5% and 30.7% ) , followed by halogenated hydrocarbon, accounting for 27.4% , and the last one was olefins, with only 10.4%. By means of ozone formation potential, the analysis results showed that olefins and aromatic hydrocarbon compounds were the two important materials which made the biggest contribution to the formation of ozone in the atmosphere of Beibei. We further analyzed the sources of VOCs in atmosphere of Beibei by the method of Principal Component Analysis (PCA). Vehicle exhaust was the biggest source and its contribution to VOCs was 50. 41%. The calculated results with T/B value also confirmed that traffic was the biggest source contributing to the VOCs in atmosphere of Beibei.

To study the characteristics of atmospheric pollutants in the urban area of Beibei district of Chongqing, the concentrations of the atmospheric pollutants were measured by automatic on-line continuous monitoring equipments from Jan. 2012 to Feb. 2013. The results showed that the concentrations of the pollutants often exceeded the corresponding values of the new National Ambient Air Quality Standards (GB 3095-2012) except SO2. Of these pollutants, PM2.5 was the most serious in this area. The concentrations of the atmospheric pollutants had significant seasonal variation. The concentrations of O3 and O(x) were both the highest in summer and the lowest in winter. The average concentrations of O3 were (36.1 +/- 19.2), (48.8 +/- 32.6), (29.8 +/- 28.6) and (18.2 +/- 15.8) microg x m(-3), and the average O(x) concentrations were (77.6 +/- 20.6), (91.3 +/- 37.6), (77.5 +/- 30.6) and (69.4 +/- 18.2) microg x m(-3) in spring, summer, autumn and winter in 2012, respectively. The concentrations of NO(x) appeared higher in winter and lower in summer, the average concentrations of NO, NO2 and NO(x) were (11.8 +/- 9.4), (42.3 +/- 13.1) and (54.1 +/- 20.8) microg x m(-3) in spring, (8.2 +/- 4.9), (40.5 +/- 9.9) and (48.7 +/- 12.6) microg x m(-3) in summer, (20.7 +/-17.1), (47.2 +/- 14.1) and (67.9 +/- 25.5) microg x m(-3) in autumn, and (30.4 +/- 25.1), (51.2 +/- 15.9), (81.6 +/- 37.9) microg x m(-3) in winter. The concentrations of SO2 appeared higher in spring and winter, and lower in summer and autumn. The concentrations of SO2 were (50.5 +/- 23.3), (26.3 +/- 16.7), (38.8 +/- 18.4) and (53.7 +/- 23.4) microg x m(-3) in spring, summer, autumn and winter, respectively. The concentrations of PM2.5 appeared higher in winter and changed smoothly in other seasons, with the average concentration of (61.4 +/- 28.5), (68.1 +/- 32.5), (61.9 +/- 27.1) and (89.6 +/- 44.2) microg x m(-3) in spring, summer, autumn and winter, respectively. The curves of diurnal variations of O3, O(x), NO, NO(x) and SO2 all showed single peak. However, the time of the peak values varied for different pollutants, 16:00 for O3 and O(x), and 8:00-11:00 for NO, NO(x) and SO2. The diurnal variations of NO2 and PM2.5 were similar to the two peaks that appeared in the morning and at night, respectively. Moreover, the diurnal ranges of O3 and O(x) concentrations were much wider in summer, while the wider ranges were observed in winter for NO, NO2, NO(x), SO2 and PM2.5. There was no difference in the diurnal pattern of NO between weekends and weekdays, the concentrations of N2O in weekdays were much higher than those on weekends, but with O3 the situation was the opposite. Correlation analysis indicated that the O3 concentration was positively correlated with temperature and wind speed, while negatively correlated with relative humidity. However, the situation of NO(x) was the opposite. PM2.5 concentration was negatively correlated with temperature and wind speed, while positively correlated with relative humidity. SO2 concentration had different correlations with the meteorological parameters in different seasons. In addition, wind direction was an important factor affecting the concentrations of the atmospheric pollutants.

To illuminate the air pollution situation of the tourist city of Qinhuangdao, the atmospheric pollutants were measured from autumn 2009 to summer 2010. The results showed that the mean average concentration of NO, NO2, SO2, O3 and PM10 during the observation period reached (18 +/- 18), (45 +/- 18), (42 +/- 46), (44 +/- 25) and (128 +/- 77) microg x m(-3), respectively. The particulate matter pollution was serious, and the rate of the annual mean value exceeded the National Ambient Air Quality Standard II by 28%. The average daily concentration and average max hourly O3 concentration were (64 +/- 21)microg x m(-3) and (126 +/- 42) microg x m(-3) in summer, and the air masses from the southern ocean aggravated the O3 pollution. The concentrations of NO(x) SO2 and PM10 in the heating period were 1.5, 4.9 and 1.5 times more than those in the period without heating and the daily average concentration of SO2 and PM10 exceeded the National Ambient Air Quality Standard II by 53% and 11% in the heating period, respectively. The superimposition effect of regional transport in the Beijing-Tianjin-Hebei region and industrial area surrounding the Bohai Bay and local harbor emission led to an increase of 17% (NO(x)), 27% (SO2) and 12% (PM10), resulting in average concentrations of up to (100 +/- 49), (110 +/- 84) and (215 +/- 108) microg x m(-3) in winter. The winds from northern inland and southern ocean can effectively remove the air pollutants.

In order to understand the change of background concentration of air pollutants with the development of economy in the region of North China, the concentrations of NO(x), O3 and PM2.5 were monitored during the summer of 2008 to 2011 at Xinglong station, which is the regional background station of North China. The results indicated that the average concentration of NO(x) in the summer of the four years was (9.1 +/- 5.1), (5.9 +/- 2.6), (12.2 +/- 4.6) and (14.1 +/- 5.0) microg x m(-3), respectively, the daily maximum hourly concentration of O3 was (163.3 +/- 42.7), (175.2 +/- 48.8), (199.6 +/- 52.6) and (207.2 +/- 62.1) microg x m(-3), respectively, and the average concentration of PM2.5 was (59.8 +/- 44.6), (44.4 +/- 28.0), (58.1 +/- 34.2) and (52.5 +/- 36.7) microg x m(-3), respectively; in which, the concentrations of atmospheric pollutants had increased most significantly in 2010, especially the concentration of NO(x). The average concentrations of NO(x), O3 and PM2.5 increased by 106%, 14% and 31%, respectively, compared to those in the summer of 2009. Because of the increase in the number of motor vehicle and the fast development of industry in the region of North China in 2010, the background concentrations of atmospheric pollutants were increasing obviously. The atmospheric oxidizer has also increased, the concentration of O(x) reached (155.3 +/- 40.2) microg x m(-3) and has increased by 20% compared to the average concentration of the period during the summer of 2009, the compound pollution of high concentration of ozone and fine particles becomes more and more serious in North China.

In order to evaluate the potential impact of the atmospheric pollution in Beijing by those cities which located southwest of it, the observations of PM10, NO(x) and O3 were conducted during the period of summer-autumn (Jul. 16-Oct. 15, 2009) in Beijing, Zhuozhou, Baoding and Shijiazhuang online, with the automated instruments which conform to international standards. The results showed that the principal pollutant was PM10, and the average concentration was (99 +/- 88), (121 +/- 74), (141 +/- 92) and (180 +/- 107) microg/m3, respectively. The concentration of NO(x) was (66 +/- 48), (23 +/- 14), (47 +/- 35) and (52 +/- 32) microg/m3, respectively. Ozone, the photochemical pollutant, the daily maximum concentration hourly was (107 +/- 60), (128 +/- 55), (164 +/- 61) and (120 +/- 54) microg/m3, respectively. Owing to the emission of local sources, the atmospheric PM10 pollution of Shijiazhuang was the most serious in 4 cities, in order was Baoding, Zhuozhou and Beijing. However, the average concentration of O3 in Baoding was the highest for the dual influence of Beijing and Shijiazhuang. Two episodes of heavy regional atmospheric pollution in July 2009 were analyzed with the surface meteorological data and backward trajectory model. The results suggested that the air quality in Beijing and the surrounding areas was significant influenced by the three cities of Hebei province in summer-autumn.

To illuminate the air pollution situation of the new Tangshan industrial area in the heating period, the observation of atmospheric pollutants was conducted in Tangshan City, Qianan City and Caofeidian Town from Oct. 2009 to Apr. 2010. The result showed that air pollution was serious in the area in winter. The regional mean concentration of NO, NO2, SO2, CO, PM2.5 and PM10 reached (26 +/- 28), (52 +/- 27), (72 +/- 53), (3 500 +/- 3 600), (82 +/- 65), (164 +/- 121) microg x m(-3) in the heating period, respectively. The concentration of NO and SO2 was 2.5 times in the heating period more than in the non-heating period. The concentration of NO2 and PM10 increased by -30%. The rates that CO and PM10 exceeded the National Ambient Air Quality Standard II were 27% and 40%; and the rate that PM2.5 exceeded the WHO IT1 Standard was 38%. The typical diurnal variations of NO, NO2, SO2, PM2.5 and PM10 were similar with peaking at 08:00 and 18:00, but the diurnal variation of CO was single peak at 08:00 with accumulating in evening. The peaks of NO, CO and SO2 were very high in morning because of the rush hours and the heating, which were 50, 90, and 5100 microg x m(-3), respectively. The peaks of NO2, PM2.5 and PM10 were relatively gentle, which were 56, 105, and 202 microg x m(-3), respectively. The cluster analysis of backward trajectories showed only the northerwinds, the cold airs can wash away the air pollution, while the southerwinds and easternwinds can easily accumulate the pollutants or transport the pollutants to the Beijing-Tianjin region.

In order to study regional air quality, evaluate the interaction of air quality among Beijing and four cities and assess the effects of regional collaborative emission abatement in Beijing and surrounding areas for the Olympic Games period on regional air quality, and seek an effective means of early warning of air pollution, a monitoring network on observation of atmospheric pollutants in Beijing and four nearby cities which were Zhuozhou, Langfang, Xianghe and Yanjiao, was established to measure concentrations of NO(x), O3 and particulate matter in June 2008. The results show that the primary pollutants in Beijing and nearly surrounding areas are particulates during the study periods. The average mass concentrations of PM10 were (114 +/- 66) microg/m3 and (128 +/- 59) microg/m3 in Beijing and nearby cities, respectively, while the average mass concentrations of PM2.5 were (77 +/- 47) microg/m3 and (81 +/- 51) microg/m3, respectively. The average maximum hourly mass concentrations of O3 were (164 +/- 52) microg/m3 and (165 +/- 55) microg/m3, as well as the average mass concentrations of NO(x) were (58 +/- 23) microg/m3 and (25 +/- 14) microg/m3 in Beijing and nearby cities, respectively. Compared to June, concentrations of PM10, PM2.5, O3, NO(x) decreased by 69%, 62%, 18% and 41% during the Olympic period (from August 8 to 24) and 56%, 49%, 17% and 16% during the Paralympic Games period (from September 6 to 17) in Beijing. The mass concentration of PM2.5 was affected by the surrounding areas of Beijing seriously. The relative high concentrations of NO(x) in Beijing implied NO(x) had the potential tendency to be transported to the surrounding areas. Ozone showed regional pollution characteristics in summer. It shows that the monitoring network on observation of atmospheric pollutants in Beijing and nearly surrounding areas is significant in early warning of air pollution, and could provide scientific support for interregional cooperation of air pollution control.

Atmospheric pollutants and their concentration change characteristics during Beijing Olympics in Shijiazhuang were studied. Air quality was measured by automatic on-line continuous monitoring equipments in summer and autumn of 2007 and 2008. The objectives of this study were to identify the effect of pollutants decrease on atmospheric environment, and develop the potential influence to Beijing and surrounding areas. The results show that the pollutants concentration often exceeds state criterion except nitrogen oxides, O3 concentration in summer and autumn is higher, averaged hourly maximum concentration (O3-Max) is (177.2 +/- 63.0) and (105.8 +/- 61.7) microg x m(-3), the concentrations of NO and NO2 are (4.5 +/- 4.0), (32.7 +/- 12.4) microg x m(-3) and (21.5 +/- 16.9), (60.5 +/- 16.9) microg x m(-3) respectively, SO2 concentration is (72.0 +/- 27.5) and (92.0 +/- 44.4) microg x m(-3), PM2.5 and PM10 concentrations reach to (102.3 +/- 47.6), (153.3 +/- 58.3) microg x m(-3) and (95.8 +/- 50.0), (147.4 +/- 67.0) microg x m(-3). Generally, pollutants declined obviously in Olympics period, the concentrations of NOx, O3-Max, SO2, PM2.5 and PM10 are (43.8 +/- 15.0), (142.0 +/- 54.9), (52.4 +/- 18.8), (76.7 +/- 35.1) and (116.5 +/- 38.8) microg x m(-3), and the reduction ratio of SO2, PM2.5 and PM10 are 34.6%, 22.8% and 21.0% compared with the whole monitoring period in 2008. The actuality of atmospheric pollution in summer and autumn was analyzed systemically, and which provided scientific evidences for evaluating the control measures of pollutants emission.