Refinement of sensitive azides via in situ generated azole-based metal-organic frameworks towards stable energetic materials.

Energetic materials (EMs) have been widely employed in both military and civilian areas for nearly two centuries. The introduction of high-energy azide anions to assemble energetic metal-organic frameworks (EMOFs) is an efficient strategy to enhance energetic properties. However, azido-based EMOFs always suffer low stabilities to external mechanical stimulation. Herein, we employed an in situ hydrothermal reaction as a technique to refine azide anions with a neutral triazole-cyano-based ligand TrzAt (TrzAt = 2-(1H-1,2,4-triazol-1-yl)acetonitrile) to yield two tetrazole-based EMOFs, namely, [ZnBr(trmetz)]n1 and [Cd(trmetz)2]n2 (Htrmetz = 5-(1,2,4-triazol-1-ylmethyl)-1H-tetrazole). Compound 1 features a closely packed 2D layered network, while compound 2 exhibits a 3D architecture. With azide anions inlaid into a nitrogen-rich and chelating ligand in the EMOFs, compounds 1 and 2 present remarkable decomposition temperatures (Tdec ≥ 300 °C), low impact sensitivities (IS ≥ 32 J) and low friction sensitivities (FS ≥ 324 N). The calculated heat of detonation (ΔHdet) values of 1 and 2 are 3.496 and 4.112 kJ g-1, respectively. In particular, the ΔHdet value of 2 is higher than that of traditional secondary explosives such as 2,4,6-trinitrotoluene (TNT, ΔHdet = 3.720 kJ g-1). These results indicate that EMOFs 1 and 2 may serve as potential replacements for traditional secondary explosives. This work provides a simple and effective strategy to obtain two EMOFs with satisfactory energy densities and reliable stabilities through an in situ hydrothermal technique for desensitization of azide anions.

Coordination polymerization of nitrogen-rich linkers and dicyanamide anions toward energetic coordination polymers with low sensitivities.

The design and synthesis of energetic materials (EMs) with high energy and reliable stabilities has attracted much attention in the field of EMs. In this work, we employed a strategy of the coordination polymerization of mild dicyanamide ions (DCA-), two isomeric ligands 1-methyl-5-aminotetrazole (1-MAT) and 2-methyl-5-aminotetrazole (2-MAT) to construct energetic coordination polymers (ECPs). Four new ECPs {[Co(DCA)2(1-MAT)2]·H2O}n1, [Cu(DCA)2(1-MAT)]n2, [Cd(DCA)2(1-MAT)2]n3 and [Cd(DCA)2(2-MAT)2]n4 were successfully synthesized through solvent evaporation routes. Compounds 1 and 4 display 1D chains, while 2 and 3 exhibit 2D-layered structures. Compounds 1-3 with the 1-MAT ligand all exhibit reliable thermal stabilities (> 200 °C). The calculated heats of detonation (ΔHdet) of 1-3 are all higher than 1.4 kJ g-1, which are higher than traditional explosive TNT (1.22 kJ g-1) and the reported ECP AgMtta (HMtta = 5-methyl-1H-tetrazole, ΔHdet = 1.32 kJ g-1). Furthermore, sensitivity testing demonstrates that 1-4 features low mechanical sensitivity to external mechanical action in contrast with the extremely sensitive azide-based ECPs [Cu3(2-MAT)2(N3)6]n. In addition, compound 2 shows hypergolic properties via an 'oxidizer-fuel' drop experiment, demonstrating its application prospects in the field of propellants. This work details an approach of synthesizing multipurpose ECPs with reliable stabilities by introducing mild dicyanamide anions into nitrogen-rich skeletons.

Effects of strontium-incorporated micro/nano rough titanium surfaces on osseointegration via modulating polarization of macrophages.

Macrophages perform multiple functions in both inflammation and wound healing, and are one of the fore front cells during implant osseointegration that influence subsequent process. Essential trace element modification may effectively modulate titanium implant surface biological properties. In this work, strontium (Sr) incorporated micro/nano rough titanium surfaces (Sr-SLA) was fabricated by hydrothermal treatment, and immunoreaction of macrophages was further investigated. In vitro results revealed that Sr doping inhibited inflammatory response of macrophages, further attenuated the inhibitory effect on following bone marrow derived cells (BMSCs) osteogenic differentiation. The regulation of macrophages by Sr-SLA likely involved ERK signaling pathway. Consistently, the in vivo study showed that compared with titanium surface sand-blasted with large grit and double acid-etched (SLA) implants, Sr-SLA implants could enhance new bone formation accompanied with more alternatively activated M2 macrophages infiltration and less classically activated M1 macrophages infiltration. These results reveal the immunomodulatory ability of Sr-SLA of adjusting the functional status of macrophages through inhibiting M1 polarization while promoting M2 polarization.

Calcium-based efficient cathode-ray scintillating metal-organic frameworks constructed from π-conjugated luminescent motifs.

Efficient cathode-ray scintillating metal-organic frameworks are constructed from a π-conjugated luminescent motif and light Ca(ii) ions. The luminescence self-quenching pathway has been effectively hindered through coordination. In situ vacuum ultraviolet fluorescent spectra have shown the excitons recombining in the scintillation process for the first time.

Highly Stable Energetic Coordination Polymer Assembled with Co(II) and Tetrazole Derivatives.

A solvothermal reaction of Co(CH3COO)2·4H2O and 5-mercapto-1-methyl-tetrazole (Hmmtz) in methanol (MeOH) yielded a one-dimensional solvent-free energetic coordination polymer, namely, [Co(mmtz)2] n 1, which was structurally characterized. The enthalpy of formation (Δf H°) of 1 (907 kJ mol-1) is much larger than that of commercial 2,4,6-trinitrotoluene (-59 kJ mol-1). The impact sensitivity and the friction sensitivity are greater than 40 J and 360 N, respectively, indicating that compound 1 exhibits a potential application as a safe explosive. Temperature-dependent molar magnetic susceptibilities show that weak antiferromagnetic behavior exists in 1.

Efficient X-ray scintillating lead(ii)-based MOFs derived from rigid luminescent naphthalene motifs.

Solid-state X-ray scintillators are widely applied in medical imaging and space exploration. However, it is still a great challenge to probe into the intrinsic nature of scintillating behaviour due to the ambiguous structure-function relationship. Herein, four structure-defined X-ray scintillating Pb(ii)-based metal-organic frameworks (SMOFs) were successfully obtained under solvothermal conditions, [Pb(1,4-ndc)(DMF)]n (SMOF-1), [Pb(1,4-ndc)(DMA)]n (SMOF-2), [Pb2(2,6-ndc)2(H2O)]n·nDMF (SMOF-3) and [Pb4(2,6-ndc)3Cl2]n (SMOF-4), where 1,4-H2ndc = 1,4-naphthalene dicarboxylate, 2,6-H2ndc = 2,6-naphthalene dicarboxylate, DMF = N,N-dimethylformamide, and DMA = N,N-dimethylacetamide. SMOFs 1-4 show scintillating signals under X-rays triggered by a highly purified tungsten target. Compared with SMOFs 1-3, SMOF-4 exhibits excellent scintillating performance owing to its solvent-free and denser structure, which favours more efficient conversion ability of X-rays to visible light. X-ray stimulated luminescence (XSL) spectra present multiple emission peaks, which is further confirmed by wavelength-dependent luminescence spectra under UV-Vis light, and density of state and DFT calculations. The synergistic effects of heavy metal Pb(ii) centres as effective X-ray absorbers and organic ligands as luminescent motifs endow these Pb(ii)-based MOFs with application prospects in X-ray detection.

Efficacy of autologous conjunctival flap on repairing the late-onset filtering bleb leakage.

AIM: To evaluate the effectiveness of autologous conjunctival flap surgery for repairing the late-onset filtering bleb leakage after trabeculectomy. METHODS: This study retrospectively reviewed 106 eyes from 106 patients with late-onset filtering bleb leakage after trabeculectomy who received autologous conjunctival flap surgery at the Zhongshan Ophthalmic Centre from 2005 to 2015. The basic information was recorded, and the interval time between trabeculectomy and autologous conjunctival flap surgery as well as related risk factors, intraocular pressure (IOP), anterior chamber depth (ACD) and best corrected visual acuity (BCVA) were analysed. Moreover, 41 patients who completed the 1-year follow up were analysed to determine the IOP and BCVA changes and long-term success rates. RESULTS: The 50 male and 56 female subjects (average age 39.13±17.96y) included 47 (44.34%) and 33 (31.13%) cases of primary open angle and primary angle-closure glaucoma. The mean interval between trabeculectomy and repair surgery was 60.60±56.92 (3-264)mo. The mean mitomycin (MMC) concentration during trabeculectomy was 0.27±0.04 (0.12-0.4) mg/mL in the fornix-based conjunctival flap group (68 patients) and 0.28±0.04 (0.20-0.33) mg/mL in the limbal-based conjunctival flap group (11 patients). After bleb leakage, the patients' vision remained stable while the IOP decreased from 10.25±4.76 (3-20.86) to 9.44±4.33 (2-21) mm Hg (P<0.01). In the 41 analysed patients, the IOP was controlled at 15.68±5.11 (7-40) mm Hg in the 1st year after autologous conjunctival flap surgery and recurrence was not observed, for a long-term success rate of 100%. CONCLUSION: Autologous conjunctival flap repairing surgery is an effective technique for sealing filtering bleb leakages and controlling IOP postoperatively.

A nanowire array with two types of bromoplumbate chains and high anisotropic conductance.

Crystalline nanowire arrays would create great opportunity for novel electrical application. Herein, we report a metal halide-based crystalline nanowire array, which was the first example constructed from two types of bromoplumbate anion chains. The single crystal shows high anisotropic conductivity with semiconducting transport along the c axis and an insulating feature perpendicular to the c direction.

Longitudinal Cohort Study on the Incidence of Primary Open-Angle Glaucoma in Bai Chinese.

PURPOSE: The prevalence of primary open-angle glaucoma (POAG) in China has been reported previously, and was lower than that in white and black populations. However, the incidence of POAG in China has not been reported. Therefore, a longitudinal study was conducted to determine the 5-year cumulative incidence and predictors of POAG in China. DESIGN: Population-based cohort study. METHODS: A total of 1520 participants (71.3% of the subjects in the baseline survey) of Bai ethnicity were examined and followed for 5 years. Glaucoma was defined based on the International Society of Geographical and Epidemiological Ophthalmology Classification criteria. Multivariable logistic regression models were fitted to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs). RESULTS: A total of 19 new cases of POAG were detected. The 5-year cumulative incidence of POAG was 1.3% (95% CI, 0.7-1.9). In multivariate analyses, incident POAG was associated with baseline variables including increased age (OR, 4.3; 95% CI, 1.4-13.8; P = .02; 70 years or older vs 50-59 years), elevated IOP (OR, 3.5; 95% CI, 2.0-5.9; P < .001; per 10 mm Hg increase), lower education level (OR, 0.3; 95% CI, 0.1-0.8; P = .02; post-primary education vs no formal education), and the presence of myopia (OR, 3.4; 95% CI, 1.3-8.6; P < .01). CONCLUSIONS: The average annual incidence of POAG in Bai Chinese was lower than that in populations of African descent and white race. The results are important to elucidate the racial/ethnic difference in POAG incidence and for the clinical management and health resource allocation in China.

Nitrogen-Rich Tetranuclear Metal Complex as a New Structural Motif for Energetic Materials.

For designing energetic materials (EMs), the most challenging issue is to achieve a balance between energetic performance and reliable stability. In this work, we employed an efficient and convenient method to synthesize a new class of EMs: nitrogen-rich tetranuclear metal complexes [M(Hdtim)(H2O)2]4 (M = Zn 1, Mn 2; H3dtim = 1H-imidazol-4,5-tetrazole) with the N content of >46%. The structural analyses illustrate that isomorphous compounds 1 and 2 feature isolated hollow ellipsoid tetranuclear units, which are linked by both π-π interactions and hydrogen-bonding interactions to give a 3D supramolecular architecture. Compounds 1 and 2 exhibit prominent energetic characteristics: excellent detonation performances and reliable thermal, impact, and friction stabilities. Being nitrogen-rich tetrazolate compounds, the enthalpies of combustion of 1 (-11.570 kJ g-1) and 2 (-12.186 kJ g-1) are higher than those of classical EMs, RDX and HMX, and they possess high positive heats of formation. Sensitivity tests demonstrate that 1 and 2 are insensitive to external mechanical action. Excellent energetic performances and low sensitivities promote 1 and 2 to serve as a new class of promising EMs with a desirable level of safety.

Preparation and evaluation of HPMC-based pirfenidone solution in vivo.

CONTEXT: Pirfenidone (PFD) has exhibited therapeutic potential in the treatment of cell proliferative disorders. The previously developed 0.5% water-based PFD eye drops by our team exhibited antiscarring effectiveness and ocular safety but with a limit of short half-life and poor bioavailability. OBJECTIVE: To increase bioavailability of the water-based PFD eye drops, we prepared a viscous solution by adding hydroxypropyl methylcellulose (HPMC, F4M), which acted as a viscosity-enhancer. Subsequently, we compared the HPMC-based PFD solution with the water-based PFD eye drops. MATERIALS AND METHODS: PFD solution with 1% HPMC (w/v) was prepared, and the viscosities at different shear rates were measured to investigate its rheology. PFD concentrations in the tear, aqueous humor, conjunctiva, cornea, and sclerae of New Zealand rabbits were detected at different time points with high-performance liquid chromatography (HPLC) following single instillation of the 0.5% PFD (w/v) water-based eye drops or HPMC-based solution. RESULTS: Compared with the 0.5% water-based PFD eye drops, the HPMC-based solution increased the PFD levels in tears and prolonged the residence time from 10 to more than 20 min (p < .01). Consequently, the concentrations of PFD in aqueous humor, conjunctiva, cornea, and sclera were elevated to varying degrees until 90 min after topical administration. CONCLUSIONS: The developed formulation possesses a same readily administration and simple preparation as the PFD eye drops; however, the HPMC-based solution exhibited the higher bioavailability.

Grinding size-dependent mechanoresponsive luminescent Cd(ii) coordination polymer.

In this work, we report a new mechanoresponsive luminescent Cd(ii) coordination polymer that exhibits a sensitivity to mechanical stimulation. The luminescence colour changed gradually from weak yellowish-green to bright cyan in response to different grinding sizes, thereby showing interesting mechanochromic properties, namely a grinding-enhanced luminescence and good crystalline maintenance ability.

Prevalence, types and awareness of glaucoma in a multi-ethnic population in rural China: the Yunnan Minority Eye Study.

PURPOSE: To determine the prevalence, types and awareness of glaucoma in a rural community in China and to examine possible ethnic variations. METHODS: The Yunnan Minority Eye Study was a multi-ethnic community-based eye survey using random cluster sampling strategies. 2133 Bai, 2205 Han and 2208 Yi Chinese aged 50 years or older participated in this study. Glaucoma including primary open-angle glaucoma (POAG), primary angle-closure glaucoma (PACG) and secondary glaucoma was defined based on the International Society of Geographical and Epidemiological Ophthalmology criteria. RESULTS: The overall age-standardized prevalence of all glaucoma was 2.6% (95% confidence interval [CI]: 2.2-3.1%) in this population. It was 1.8% (95% CI: 1.1-1.9%) for POAG and 0.5% (95% CI: 0.9-1.6%) for PACG, respectively. Among 29 people with secondary glaucoma, 27 (93%) were blind in at least one eye. The presence of primary open-angle glaucoma was associated with male gender (odds ratio [OR] = 2.94; comparing men with women), Yi ethnicity (OR = 2.27; comparing Yi with Han people), higher IOP (OR = 1.09 per mmHg increase), and the presence of myopia (OR = 1.84). Of the 212 participants with glaucoma, only 38 (18%) were aware of the disease and had been diagnosed previously as having glaucoma or suspected glaucoma. Patients who were better educated tended to be aware of the disease. CONCLUSIONS: Significant ethnic difference in the prevalence of POAG was observed in this study. The low awareness of glaucoma highlights the pressing need to increase public awareness of this potentially blinding condition in rural China.

Intraocular Pressure-Lowering Potential of Subthreshold Selective Laser Trabeculoplasty in Patients with Primary Open-Angle Glaucoma.

Purpose. To compare the efficacy of subthreshold and conventional selective laser trabeculoplasty (SLT) in lowering intraocular pressure (IOP) in the patients with primary open-angle glaucoma (POAG). Methods. Fifty-two eyes from fifty-two POAG patients were randomized into two groups, one group treated with subthreshold SLT using two-thirds of the conventional energy and the other one treated with the conventional energy. IOP was measured with the Goldmann tonometer and the anterior chamber inflammation was determined using laser flare meter. Results. The initial energy dosage used in subthreshold SLT group was significantly lower than the amount of the energy used in conventional SLT group (0.4 ± 0.1 mJ versus 0.6 ± 0.1 mJ, P = 0.030). The total energy dosage was also significantly lower in subthreshold SLT group compared to the other group (37.6 ± 3.3 mJ versus 51.8 ± 5.7 mJ, P = 0.036). However, the level of inflammation in aqueous humor, amount of reduction in IOP, and the success rate in controlling IOP was the same in both groups. Conclusion. The efficacy of subthreshold SLT group in reducing IOP in POAG patients is comparable to the efficacy of conventional SLT group.

Human cytomegalovirus-encoded US28 may act as a tumor promoter in colorectal cancer.

AIM: To assess human cytomegalovirus-encoded US28 gene function in colorectal cancer (CRC) pathogenesis. METHODS: Immunohistochemical analysis was performed to determine US28 expression in 103 CRC patient samples and 98 corresponding adjacent noncancerous samples. Patient data were compared by age, sex, tumor location, histological grade, Dukes' stage, and overall mean survival time. In addition, the US28 gene was transiently transfected into the CRC LOVO cell line, and cell proliferation was assessed using a cell counting kit-8 assay. Cell cycle analysis by flow cytometry and a cell invasion transwell assay were also carried out. RESULTS: US28 levels were clearly higher in CRC tissues (38.8%) than in adjacent noncancerous samples (7.1%) (P = 0.000). Interestingly, elevated US28 amounts in CRC tissues were significantly associated with histological grade, metastasis, Dukes' stage, and overall survival (all P < 0.05); meanwhile, US28 expression was not significantly correlated with age, sex or tumor location. In addition, multivariate Cox regression data revealed US28 level as an independent CRC prognostic marker (P = 0.000). LOVO cells successfully transfected with the US28 gene exhibited higher viability, greater chemotherapy resistance, accelerated cell cycle progression, and increased invasion ability. CONCLUSION: US28 expression is predictive of poor prognosis and may promote CRC.

Color tunable and near white-light emission of two solvent-induced 2D lead(II) coordination networks based on a rigid ligand 1-tetrazole-4-imidazole-benzene.

Two new lead(II) coordination polymers, [Pb(NO3)(tzib)]n (1) and [Pb(tzib)2]n (2), were successfully synthesized from the reaction of a rigid ligand 1-tetrazole-4-imidazole-benzene (Htzib) and lead(II) nitrate in different solvents. The obtained polymers have been characterized by single-crystal X-ray diffraction analyses, which show that both polymers feature 2D layer structures. The inorganic anion nitrate in 1 shows a µ2-κO3:κO3 bridging mode to connect adjacent lead ions into a zigzag chain, and then the organic ligands tzib(-) join the neighboring chains into a 2D layer by a µ3-κN1:κN2:κN6 connection mode. In 2, there are two different bridging modes of the tzib(-) ligand: µ3-κN1:κN2:κN6 and µ3-κN1:κN6 to coordinate the lead ions into a 2D layer structure. Interestingly, both polymers displayed broadband emissions covering the entire visible spectra, which could be tunable to near white-light emission by varying excitation wavelengths.

Role of licochalcone A on thymic stromal lymphopoietin expression: implications for asthma.

Asthma is a common chronic inflammatory disease characterized by the infiltration and accumulation of memory-like Th2 cells and eosinophils. Viral infection has emerged as the most common cause of severe episodes of asthma. For the treatment of bronchial asthma, the root of liquorice (Glycyrrhiza glabra) has been used as a traditional medicine in the East and West. Licochalcone A is the predominant, characteristic chalcone in liquorice root. To determine whether licochalcone A possesses an anti-inflammatory effect, we tested its effect on the expression and production of thymic stromal lymphopoietin (TSLP) in BEAS 2B cells and primary bronchial epithelial cells. We found that polyinosinic-polycytidylic acid (poly-IC)-induced TSLP expression was suppressed by treatment with licochalcone A in a dose- and time-dependent manner. We also found that poly-IC-induced mRNA expression of other proinflammatory mediators such as MCP-1, RANTES, and IL-8 was suppressed by licochalcone A. Furthermore, licochalcone A suppressed poly-IC-induced nuclear factor kappa B (NF-κB) nuclear translocation and DNA-binding activity by suppressing the Iκß kinase (IKK) activity but not by direct phosphorylation of p65 at serine 276. Collectively, our findings suggest that licochalcone A suppresses poly-IC-induced TSLP expression and production by inhibiting the IKK/NF-κB signaling pathway, which might be involved in the pathogenesis of virus-exacerbated asthma. Further elucidation of the mechanisms underlying these observations can help develop therapeutic strategies for virally induced asthma.

[Optimization of urban green space spatial arrangement based on supply-demand analysis: a case study in Nanjing City, China].

Urban green space has the functions of ecological and social services, and the two services levels are decided by the supply-demand relationship. However, the supply-demand of green space not only involves in quantity, but also refers to spatial distribution. Therefore, only greening indicators can not wholly reflect the true levels of green space services. Based on the supply-demand analysis and supported by the ArcGIS, this paper examined the ecological and social services levels of the urban green spaces in Nanjing City by using the evenness indicator and the rate the people could enjoy the public green space in their accessible area. Accordingly, the ecological and social services levels of the green space in the City were investigated. The results showed that in the east of Nanjing City, green spaces were rich, but high accessible ones were lack, which resulted in a moderate social service level. In the center of the City, green spaces were lack and distributed unevenly, resulting in the low levels of ecological and social services. In Hexi area, due to the shortage in ecological green space and its uneven distribution, the green spaces had a high level social service but a low level ecological service. In the southern and northern areas of the City, green spaces were in deficiency, uneven distribution, and lack in high accessible.

[Coupling coordination measurement of urbanization and eco-environment system in Huaihe River Basin of China based on fuzzy matter element theory].

Based on the statistical data of urbanization and eco-environment of 35 cities in the Huaihe River Basin of China in 2010, an index system of urbanization-eco-environment system was established by using fuzzy matter element theory, and the weight of each indicator was calculated by entropy method. The improved function of the coupling coordination degree of urbanization and eco-environment was constructed to measure this coupling coordination degree in the Huaihe River Basin. In 2010, the development level of urbanization subsystem in the Basin was lower than that of the eco-environment subsystem, and the integrated coordination index of urbanization and eco-environment was 0.186, indicating that there was a gap between the two types of indicators. The average coupling degree of urbanization and eco-environment was 0.475, indicating that the urbanization-eco-environment system was at antagonistic stage. There was a greater difference in the development level of urbanization subsystem, but a smaller difference in the development level of eco-environment subsystem among the cities. The average value of the coordination degree of all the cities was 0.706, indicating that the Huaihe River Basin was at high coordination coupling stage, and the integrated coherence and synergistic effect of urbanization and eco-environment construction in the Huaihe River Basin was higher.

[Spatial heterogeneity and classified control of agricultural non-point source pollution in Huaihe River Basin].

Agricultural non-point source pollution is of importance in river deterioration. Thus identifying and concentrated controlling the key source-areas are the most effective approaches for non-point source pollution control. This study adopts inventory method to analysis four kinds of pollution sources and their emissions intensity of the chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) in 173 counties (cities, districts) in Huaihe River Basin. The four pollution sources include livestock breeding, rural life, farmland cultivation, aquacultures. The paper mainly addresses identification of non-point polluted sensitivity areas, key pollution sources and its spatial distribution characteristics through cluster, sensitivity evaluation and spatial analysis. A geographic information system (GIS) and SPSS were used to carry out this study. The results show that: the COD, TN and TP emissions of agricultural non-point sources were 206.74 x 10(4) t, 66.49 x 10(4) t, 8.74 x 10(4) t separately in Huaihe River Basin in 2009; the emission intensity were 7.69, 2.47, 0.32 t.hm-2; the proportions of COD, TN, TP emissions were 73%, 24%, 3%. The paper achieves that: the major pollution source of COD, TN and TP was livestock breeding and rural life; the sensitivity areas and priority pollution control areas among the river basin of non-point source pollution are some sub-basins of the upper branches in Huaihe River, such as Shahe River, Yinghe River, Beiru River, Jialu River and Qingyi River; livestock breeding is the key pollution source in the priority pollution control areas. Finally, the paper concludes that pollution type of rural life has the highest pollution contribution rate, while comprehensive pollution is one type which is hard to control.