Reducing traffic violations in the online food delivery industry-A case study in Xi'an City, China.

Online food delivery (OFD) is one of the top industries in the Online-to-offline (O2O) commerce sector. Deliverymen need to complete a large number of delivery orders in limited default time every day, which cause high working stress to them. Therefore, a high level of traffic violations and crashes by deliverymen and corresponding negative impact on public safety are observed. To reduce traffic violations by deliverymen and resulting crashes, a hierarchical online food delivery framework is proposed, which is based on data from questionnaire surveys conducted in Xi'an City, China. The study includes the analysis of the root cause correlated with traffic violations during online food delivery as part of an empirical study on the priority delivery fee by applying a conditional price sensitivity measurement (PSM) model. The feasibility and rationality of the framework are further investigated by using cross analysis of urban dwellers' occupation, income, and commuting cost. The results identify that, through rationally shunting the demand of online food delivery, prolonging the default delivery duration, and providing diversified delivery services, the proposed hierarchical online food delivery mechanism is able to relieve the stress of deliverymen during peak hours of food requests. This reduces the willingness of deliverymen to engage in traffic violations, and other risky behaviors during food delivery trips. All of which facilitate high-quality and timely online food delivery service while enabling improved safety of deliverymen and others as part of enhanced public safety and health.

[Pollution and Source Analysis of Heavy Metal in Surface Dust from Xi'an University Campuses].

Surface dust samples were collected from university campuses in Xi'an, and X-ray fluorescent spectrometry was used to determine the contents of nine heavy metals (Mn, As, Pb, Cr, Co, Ni, Cu, V, and Zn). Enrichment factors were subsequently used to determine the enrichment degree of each element and the preliminary determination of the pollution sources. The R programming language and SPSS were used for cluster analysis and principal components analysis to identify the pollution sources. The results showed that the average concentrations of all nine heavy metal elements were higher than their surface soil background values in Shaanxi Province; however, Mn, Co, As, V, and Ni exhibited relatively little enrichment and were less affected by human interference. Cr and Cu were moderately enriched, whereas Zn and Pb were significantly enriched, and human activities played a major role in the enrichment of these four elements. The main sources of Mn, Co, As, V, and Ni in surface dust samples from the university campuses were natural sources, whereas the accumulation of Zn, Cr, and Pb were mainly due to traffic sources, and Cu originated both from the auto repair industry and from paint coatings.

[Source Identification and Pollution Characteristics of Heavy Metals in Suspended Particles of Urban Road Dust from Xingtai City].

Fifty dust samples were collected from Xingtai City to study the source characteristics of heavy metals in suspended particles of urban road dust from industrial enterprise transformation cities. The contents of Cr, Mn, Co, Ni, Cu, Zn, As, and Pb in particles of urban road dust smaller than 100 µm were determined by X-ray fluorescence spectrometry, and their pollution levels were assessed by enrichment factor. The possible sources of heavy metals measured in the dust were identified by multivariate statistical analysis methods including correlation analysis, principal component analysis, and cluster analysis. The results indicated that in comparison to the element background values of local soil, the particles of urban road dust smaller than 100 µm from Xingtai City had higher Cr, Mn, Co, Cu, Zn, and Pb concentrations. The accumulation level of Co was the highest, followed by Zn, and Pb and Cu, whereas the other trace metals were deficient or showed minimal enrichment in the suspended road dust. The multivariate statistical analysis results showed that Cr, Mn, and Ni had significant positive correlation. These metals belong to both a principal component and a cluster, whereas Cu, Zn, and Pb belong to just a principal component. Considering the content characteristics and the results of multivariate statistical analysis of various heavy metal elements in the suspended samples, these results illustrated that the Cr, Mn, and Ni in the suspended particles of urban dust from Xingtai City roads mainly come from natural and industrial sources, whereas the Zn, Pb, and Cu originate from transportation and coal sources; As comes from natural sources, and Co is mainly affected by industrial activities.

[Contamination Levels and Source Analysis of Heavy Metals in the Finer Particles of Urban Road Dust from Xi'an, China].

Road dust samples were collected from four different functional areas in Xi'an City, i.e., an educational area, a residential area, a park area, and a traffic area, to study the influence of intensive human activities on local urban environmental quality. The contents of Cu, Pb, Zn, Cr, Co, V, Mn, and Ni in the smaller than 63 µm road dust particles were determined by X-ray fluorescence spectrometry, and the pollution levels of these metals were assessed by a geoaccumulation index and a pollution loading index. The possible sources of heavy metals measured in the dusts were identified by multivariate statistical analysis methods, including correlation analysis, principal component analysis, and cluster analysis, and the contributions of each source to heavy metals in the dusts were apportioned by a principal component analysis-multiple linear regression receptor model. The results showed that the contents of Cu, Pb, Zn, Cr, Co, V, Mn, and Ni in the smaller than 63 µm road dust particles of urban road dust from Xi'an ranged 14.2-96.9, 23.5-206.1, 20.0-899.4, 122.7-262.8, 7.9-14.2, 48.7-71.5, 274.0-448.9, and 22.4-62.5 mg·kg-1, respectively, with averages of 46.6, 97.4, 169.2, 177.5, 9.8, 57.1, 337.6, and 29.3 mg·kg-1. Compared to the element background values of Shaanxi soil, the finer particles of road dust from Xi'an had elevated contents of Cu, Pb, Zn, and Cr. The finer particles of road dust from Xi'an were unpolluted by Co, V, Mn, and Ni; unpolluted to moderately polluted by Cr, Cu, and Zn; and moderately polluted by Pb. The assessment results of comprehensive pollution indicated that the pollution levels of the heavy metals in the dusts were mainly unpolluted to moderately polluted. The multivariate statistical analysis results displayed that Cr, Cu, Pb, and Zn had significant positive correlation. These metals belong to a principal component and a cluster, whereas Mn, Ni, V, and Co belong to another principal component and cluster and have significant positive correlation. Considering the content characteristics of heavy metals in the dusts, these results illustrated that two kinds of sources for the heavy metals studied existed for the finer particles of road dust from Xi'an, i.e., Cu, Pb, Zn, and Cr mainly originated from traffic sources, whereas V, Co, Mn, and Ni were mainly from natural sources. The contributions of traffic sources and natural sources to the heavy metals in the finer particles of the road dust from Xi'an were respectively 56.7% and 43.3%.

Copper-Catalyzed Functionalizations of C60 with Amino Alcohols.

CuI-catalyzed diverse functionalizations of C60 with amino alcohols with aerobic oxygen as the sole oxidant have been explored. For 2-/3-amino alcohols, an aminooxygenation reaction occurs to generate fulleromorpholine and fullerooxazepane derivatives. When a tethered furan ring exists, a further intramolecular [4 + 2] reaction with the neighboring double bond occurs to furnish the cis-1 products. In the case of 4-/5-amino alcohols, methanofullerenes linking with cyclic amides are obtained through cyclic enamine intermediates.

[Source Apportionment of Soil Heavy Metals in City Residential Areas Based on the Receptor Model and Geostatistics].

The soils from residential areas of Xi'an city were selected as a case area. The absolute principal component scores-multivariate linear regression (APCS-MLR) model and the ordinary kriging interpolation were combined to identify and apportion the pollution sources of soil heavy metals (As, Ba, Co, Cu, Mn, Ni, Pb, Sr, Zn,V), the percentage of contribution of every source for every element, and the spatial distribution characteristics of contribution rates. Compared with the background values of cinnamon, which is the main soil type in Xi 'an, the accumulation levels of Pb, Cu, Sr, Co, Zn, Ba, Ni, As, Mn, V in soil of urban residential areas in Xi'an city decreased in turn. The standard-exceeding ratios of Ba, Co, Cu, Pb, Sr, Zn were higher than those of other studied elements. Three main pollution sources of soil heavy metals in residential areas were natural source, traffic sources, and fossil fuel combustion source, respectively. Natural source was the main source of As, Mn, Ni, V in studied residential areas. The average contribution rate of natural source for As, Mn, Ni, V was 69.63%, 74.28%, 68.65%, 77.09%, respectively. The fossil fuel combustion was the second largest contributor for their accumulation in these studied residential areas. Its contribution rate for As, Mn, Ni was 23.07%, 19.09%, 23.13%, respectively. The contribution of traffic emissions was lower. Their spatial distribution characteristics tended to be lower in west and higher in east. The average contribution rates of fossil fuel combustion source for Co, Pb, Sr, Zn were 59.84%, 42.22%, 44.50%, 44.44%, respectively. The performance of spatial distribution was increased gradually from the city center to the outside. The sources of Ba were given priority to natural source and fossil fuel combustion source, and the average contribution rates were 41.67% and 48.27%, respectively. The contribution rate of fossil fuel combustion source for Ba gradually decreased from the center of the city. The contribution rates of natural source, traffic source, and fossil fuel combustion source for Cu were 37.00%, 20.47% and 26.50%, respectively.

[Assessment of Pollution, Sources, and Risks of Polycyclic Aromatic Hydrocarbons in Soil from Urban Parks in Xi'an City, China].

A total of seventeen surface soil samples were collected from urban parks in Xi'an city. The concentration of sixteen priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by high performance liquid chromatography (HPLC). In addition, the composition, source, pollution level and a risk assessment of PAHs in surface soil of park were evaluated. The results showed that the total concentrations of sixteen PAHs ranged from 0.362 to 1.336 µg·g-1, with a mean value of 0.591 µg·g-1. The concentration of seven carcinogenic PAHs (Σ7CPAHs) ranged from 0.051 to 0.528 µg·g-1, with a mean value of 0.181 µg·g-1. Compared to the ΣPAHs levels of other cities of China, the ΣPAHs in park surface soils in Xi'an are relatively low. PAHs in the soil samples were dominated by low molecular weight PAHs with 2 and 3 rings. The results of source analysis showed that the PAHs in park surface soil mainly originated from the combustion of fossil fuels, however, the source of PAHs in some samples is complex and from mixed sources, such as oil spills, oil burning, and incomplete combustion of coal and biomass. The ecological risks of PAHs in the surface soil were evaluated according to the soil quality guidelines to be ERL (effects range low) and ERM (effects range median), and these results showed that all samples, in general, were polluted. However, the potential ecological risks of PAHs were at a low level. The incremental life cancer risk (ILCR) assessment indicated that health risks for children and adults were both in a permissible range, however, the risks for children exposed to the soil were considerably higher than for adults. Dermal contact was the main exposure pathway that resulted in the relatively higher risk, followed by ingestion.

[Distribution Characteristics and Source Analysis of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Dust of Xi'an City, China].

A total of 58 surface dust samples were collected from Xi'an city. The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography with a flame ionization detector (GC-FID). At the same time, the distribution and sources of PAHs in surface dust were studied. The results showed that the concentrations of individual PAH ranged from 14.69 to 6370. 48 microg x kg(-1), and the total concentrations of 16 PAHs (∑16 PAHs) ranged from 5039.67 to 47,738.50 microg x kg(-1), with a mean of 13,845.82 microg x kg(-1). Compared to the Y PAHs levels of other cities, the ∑16 PAHs in surface dust of Xi'an belonged to a relatively higher level. PAHs in surface dust were mainly dominated by high molecular weight PAHs with 4-6 rings and the concentration of 7 carcinogenic PAHs (1 CPAHs) accounted for 46.08% of 3 16PAHs. The mean of ∑16 PAHs in surface dust had the highest concentration at industrial area; followed by the educational area, traffic area, business and traffic area; residential area and parks showed relatively lower concentration. The average content of ∑16 PAHs in surface dust presented an increasing trend along the main urban area--the second ring road--the third ring road. ∑16 PAHs in surface dust had higher concentrations at the industrial areas of the east and west suburbs of Xi'an, the south suburb and the north section of the second ring road; ∑16 PAHs concentrations in the main urban area, north suburb and southeast part of Xi'an were relatively lower. The results of ratio, cluster analysis and principal component analysis showed that PAHs in surface dust were mainly originated from the combustion of fossil fuels and coal combustion. Among them, diesel combustion reached 36.07%, gasoline combustion accounted for 32.31%, and coal combustion was resposbe for 23.40%

[Distribution, Source and Human Exposure of Phthalic Acid Esters (PAEs) in Surface Dust in Urban Area of Xi'an City, China].

A total of 58 surface dust samples were collected in urban area of Xi'an City. High Performance Liquid Chromatography (HPLC) was used to analyze the concentrations of six phthalic acid esters (PAEs) listed as priority pollutants by United States Environmental Protection Agency (U.S. EPA). Composition, distribution, environmental sources and exposure characteristics of PAEs in the surface dust were further studied. All analyzed PAEs were detected in the surface dust. The concentration of individual PAE compounds varied from not detectable to 183.19 mg·kg-1 and their mean concentrations decreased in the order of DEHP>DnBP >>DEP >DMP >BBP >DnOP. The total concentration of six PAEs (∑6PAEs) ranged from 0.87 to 250.30 mg·kg-1 with an average of 40.48 mg·kg-1, and followed the order of parks >traffic area >mixed business and traffic area >residential area >educational area >industrial area. The ∑6PAEs presented the decreasing trend along the main urban area - the second ring road - the third ring road. The results of correlation analysis, principal component analysis and cluster analysis showed that PAEs in surface dust of Xi'an City were related to the application of plasticizers, the emission of cosmetics and personal care products along with building materials and home decoration materials. The dose order of human exposure to PAEs in surface dust was the direct ingestion by hand and mouth >>dermal adsorption >inhalation via mouth and nose. Meanwhile, the intake dose of children was higher than that of adults. However, the intake dose of DnBP, DEHP, DBP and BBP was lower than the tolerable daily intake (TDI) suggested by European Union Scientific Committee for Toxicity, Ecotoxicity and the Environment (EU CSTEE) and the reference doses (RfD) proposed by U.S. EPA.

Cu(OAc)2-promoted reaction of [60]fullerene with primary amines or diamines.

The Cu(OAc)2-promoted reaction of C60 with easily available primary amines allows the concise preparation of aziridinofullerenes. Both alkyl and aryl amines are suitable in this reaction. Moreover, the Cu(OAc)2-promoted reaction of C60 with diamines affords C60-fused cyclic 1,2-diaminated fullerenes.

Lewis base-catalyzed reaction of aziridinofullerene with ureas for the preparation of fulleroimidazolidinones.

The Lewis base-catalyzed double nucleophilic substitution reaction of N-tosylaziridinofullerene with various ureas allows the easy preparation of fulleroimidazolidinones with a high tolerance for functional groups. Alkyl-substituted ureas show better reactivity than aryl-substituted ureas.

BF3·Et2O- or DMAP-catalyzed double nucleophilic substitution reaction of aziridinofullerenes with sulfamides or amidines.

BF3·Et2O-catalyzed double nucleophilic substitution reaction of N-tosylaziridinofullerene with sulfamides has been exploited for the easy preparation of cyclic sulfamide-fused fullerene derivatives. Moreover, the Lewis base catalyzed double amination of N-tosylaziridinofullerene, with amidines as the diamine source, is demonstrated for the first time. The present methods provide new routes to cyclic 1,2-diaminated [60]fullerenes.

Hypervalent iodine reagent mediated diamination of [60]fullerene with sulfamides or phosphoryl diamides.

A hypervalent iodine-promoted intermolecular diamination reactions of C60 with sulfamides or phosphoryl diamides affords two classes of novel C60-fused cyclic sulfamide or phosphoryl diamide derivatives. The reaction between C60 and sulfamides can be effectively controlled to selectively synthesize diamination products or azafulleroids under PhIO/I2 or PhI(OAc)2/I2 conditions, respectively. Moreover, phosphoryl diamides were first used as an amine source in the diamination of alkenes.

[DNA aptamer selection in vitro for determining ketamine by FluMag-SELEX].

OBJECTIVE: To select specific DNA aptamer for determining ketamine by FluMag-SELEX. METHODS: Based on magnetic beads with tosyl surface modification as solid carrier and ketamine as target, a random ssDNA library with total length of 78 bp in vitro was compounded. After 13 rounds screening, DNA cloning and sequencing were done. Primary and secondary, structures were analyzed. The affinity, specificity and Kd values of selected aptamer were measured by monitoring the fluorescence intensity. RESULTS: Two ssDNA aptamers (Apt#4 and Apt#8) were successfully selected with high and specific abilities to bind ketamine as target with Kd value of 0.59 and 0.66 µmol/L. The prediction of secondary structure was main stem-loop and G-tetramer. The stem was the basis of stability of aptamer's structure. And loop and G-tetramer was the key of specific binding of ketamine. CONCLUSION: FluMag-SELEX can greatly improve the selection efficiency of the aptamer, obtain the ketamine-binding DNA aptamer, and develop a new method for rapid detection of ketamine.

Hypervalent iodine reagent mediated reaction of [60]fullerene with amines.

The hypervalent iodine reagent mediated reaction of C60 with various readily available amines for the easy preparation of iminofullerenes has been developed. The reaction between C60 and sulfonamides can be effectively controlled to selectively synthesize azafulleroids or aziridinofullerenes under PhI(OAc)2/I2 or PhIO/I2/CuCl/lutidine conditions, respectively. For phosphamide and urea, only one isomer is obtained. However, carbamate gives three kinds of products. Interestingly, the reaction of C60 with alkylamines allows the effective synthesis of aziridinofullerenes and regioselective cis-1-bisaziridinofullerenes.

I(2)-catalyzed direct α-hydroxylation of ß-dicarbonyl compounds with atmospheric oxygen under photoirradiation.

An I2-catalyzed hydroxylation of ß-dicarbonyl moieties using air as the oxidant under photoirradiation has been developed for the easy preparation of α-hydroxy-ß-dicarbonyl compounds. The transformation was completed with only 1 mol % of I2. With α-unsubstituted malonates, the hydroxylated dimerization product was afforded as the predominant product along with a minor product, α,α-dihydroxyl malonate.

[Correlativity study of the distribution of soil magnetic susceptibility and the heavy metal contents in Xi'an City].

The magnetic susceptibility and the concentrations of Co, Cr, Cu, Pb, Sn, Sr and Ba in topsoil samples from Xi'an City were measured to study their spatial distribution and their correlation in this study. The results show that the concentrations of all measured heavy metals are higher than their background values in Cinnamon topsoil, which is the main soil type of Xi'an City. The heavy metals concentrations and the magnetic susceptibility of the studied samples display moderate variance. Co, Cr, Cu, Pb, Sn, Sr and Ba are significantly positively correlated with low-frequency magnetic susceptibility, while are significantly negatively correlated with frequency susceptibility. The spatial distribution of low-frequency magnetic susceptibility is identical with the concentrations of Pb and Cu. However, the spatial variation of frequency magnetic susceptibility is different from the concentrations of Co, Cr and Ba. The pollution assessment results show that the heavy metal pollution in topsoil of Xi'an City is moderate. The spatial contribution of the pollution load index was significantly correlated with the magnetic susceptibility of topsoil in Xi'an City. Therefore, soil magnetic susceptibility can be used as an effective monitoring means for heavy metal pollution in urban soil.

[Sources and potential risk of heavy metals in roadside soils of Xi' an City].

Based on the X-Ray fluorescence spectroscopic measurement of heavy metals concentration in roadside soil samples from Xi' an City, and by the methods of principal component analysis, cluster analysis, and correlation analysis, this paper approached the possible sources of heavy metals in the roadside soils of the City. In the meantime, potential ecological risk index was used to assess the ecological risk of the heavy metals. In the roadside soils, the mean concentrations of Co, Cr, Cu, Mn, Ni, Pb, and Zn were higher than those of the Shaanxi soil background values. The As, Mn and Ni in roadside soils mainly came from natural source and transportation source, the Cu, Pb, and Zn mainly came from transportation source, and the Co and Cr mainly came from industry source. These heavy metals in the roadside soils belonged to medium pollution, and had medium potential ecological risk.

[Content, source and speciation of heavy metal elements of street dusts in Baoji City].

Heavy metal concentrations in street dust of Baoji City were investigated by using X-Ray fluorescence spectrometry (XRF) and atomic adsorption spectrometry (AAS). The results show that the mean concentrations of Cu, Pb, Zn, Mn, Co, Ni, Cr and Cd are 123.2, 408.4, 715.1, 804.2, 15.9, 48.8, 126.7 and 5.5 microg x g(-1), respectively, which are higher than those of the element background values of International, Chinese, and Shaanxi Soil, especially for Cu, Pb, Zn and Cd. The source of heavy metal elements in street dust of Baoji City was identifed by multivariate statistics analysis (correlation analysis, principal component analysis and cluster analysis), and the results show that Ni and Cr mainly originate from natural source (local soil); Cu, Pb, Mn and Co have mixed sources of human activities (industry and traffic) and nature (local soil); Zn and Cd represent traffic and industry sources. At the same time, the speciation characteristics of heavy metals in street dust of Baoji City were investigated by using the modified BCR sequential extraction procedure and ICP-MS. The results show that Mn, Co, Ni and Cr are dominated by residue (over 48.52%), Zn and Cd mainly exist in acetic acid extractable part (44.43% and 44.08%), Cu is rich in oxidizable (48.22%) and residual (37.65%) parts, Pb is mainly in reducible part (45.42%). The order of mobility of heavy metal elements is Cd (90.11%) > Pb (82.33%) > Zn (79.32%) > Cu (62.35%) > Mn (51.48%) > Co (29.02%) > Ni (23.62%) > Cr (18.68%), in which of them, Cd, Pb, Zn, Cu and Mn have stronger transformation (over 50%) and higher potential harm.

[Effects of Azone of different concentrations on percutaneous absorption of baicalin in vitro].

OBJECTIVE: To study the effects of azone on the percutaneous absorption of baicalin in vitro. METHODS: Using the skin of nude mice as the cutaneous barrier, the rate constants of percutaneous absorption of baicalin at various concentrations of Azone were determined. RESULTS: The rate constants were 76.07, 89.23, 167.36, 238.61, 200.45 and 171.49 microgram cm-2.h-1 respectively corresponding to the concentrations of Azone at 0, 2%, 4%, 6%, 8%, and 10%. CONCLUSION: C Azone can enhance percutaneous absorption of baicalin, exerting its maximum effect at the concentration of 6%.