Ecological niches and blood sources of sand fly in an endemic focus of visceral leishmaniasis in Jiuzhaigou,Sichuan,China

Background:Sand fly Phlebotomus chinensis is a principle vector for the visceral leishmaniasis(VL)in China with a wide geographic distribution.Jiuzhaigou,Sichuan is a mountain type endemic area of VL in China.Long term effective control efforts in the region have successfully reduced VL transmission.To assess the current status of the sand flies and their ecological aspects in the region,a survey was conducted in the summer of 2014 and 2015.Methods:Sand fly specimens were collected by light traps in a village and blood sources were identified by PCR and sequencing of the mitochondrial cytochrome b gene.Results:In a rock cave,65.2%–79.8%of collected sand flies were male.On a rabbit farm,92.9%–98.8%of specimens were female.In pig pens,61.1%of specimens were female.Some females had visible blood residues.The feeding rate was 49.4%from the pig pens,12.3%from the cave,and only 1.7%from the rabbit farm.Pig,rabbit,chicken,dog,and human blood were detected in the fed specimens.Swine blood,present in all tested samples,was a preferred blood source,while chicken and dog blood were present in a third of the samples.Conclusions:In Jiuzhaigou County,Sichuan Province of China,the considerable sandfly density and the peridomestic feeding behavior all increases the risk of VL transmission,and insecticide spraying in animal sheds could be exploited to reduce sand fly populations in human surroundings.

Population dynamics, pathogen detection and insecticide resistance of mosquito and sand fly in refugee camps, Greece

Background:As of 2015 thousands of refugees are being hosted in temporary refugee camps in Greece.Displaced populations,travelling and living under poor conditions with limited access to healthcare are at a high risk of exposure to vector borne disease(VBD).This study sought to evaluate the risk for VBD transmission within refugee camps in Greece by analyzing the mosquito and sand fly populations present,in light of designing effective and efficient context specific vector and disease control programs.Methods:A vector/pathogen surveillance network targeting mosquitoes and sand flies was deployed in four temporary refugee camps in Greece.Sample collections were conducted bi-weekly during June-September 2017 with the use of Centers for Disease Control(CDC)light traps and oviposition traps.Using conventional and molecular diagnostic tools we investigated the mosquito/sand fly species composition,population dynamics,pathogen infection rates,and insecticide resistance status in the major vector species.Results:Important disease vectors including Anopheles sacharovi,Culex pipiens,Aedes albopictus and the Leishmania vectors Phlebotomus neglectus,P.perfiliewi and P.tobbi were recorded in the study refugee camps.No mosquito pathogens(Plasmodium parasites,flaviviruses)were detected in the analysed samples yet high sand fly Leishmania infection rates are reported.Culex pipiens mosquitoes displayed relatively high knock down resistance(kdr)mutation allelic frequencies(ranging from 41.0 to 63.3%)while kdr mutations were also detected in Ae.albopictus populations,but not in Anopheles and sand fly specimens.No diflubenzuron(DFB)mutations were detected in any of the mosquito species analysed.Conclusions:Important disease vectors and pathogens in vectors(Leishmania spp.)were recorded in the refugee camps indicating a situational risk factor for disease transmission.The Cx.pipiens and Ae.albopictus kdr mutation frequencies recorded pose a potential threat against the effectiveness of pyrethroid insecticides in these settings.In contrast,pyrethroids appear suitable for the control of Anopheles mosquitoes and sand flies and DFB for Cx.pipiens and Ae.albopictus larvicide applications.Targeted actions ensuring adequate living conditions and the establishment of integrated vector-borne disease surveillance programs in refugee settlements are essential for protecting refugee populations against VBDs.

Spatial distribution of sand flies(Diptera: Psychodidae; Larroussius group), the vectors of visceral leishmaniasis in Northwest of Iran

Objective: To determine spatial distribution of sand flies(Diptera: Psychodidae; Larroussius group), the vectors of visceral leishmaniasis in Ardabil province, Northwest of Iran.Methods: Sand flies were collected using sticky traps from the 30 selected points in Ardabil province, during May-November 2017.The MaxEnt model in GIS software was used for modeling.Results: A total of 2 794 specimens of sand flies were collected, of which 33% were Larroussius subgenus sand flies.Phlebotomus kandelakii and Phlebotomus wenyoni were the highest and lowest collected species respectively.Based on the modeling, four areas in the province were identified with more than 70% probability of the presence of Larroussius group vectors which were at risk of visceral leishmaniasis disease transmission.Conclusions: The distribution of Larroussius subgenus sand flies was observed in all parts of Ardabil.But the northern parts of the province(Germi and Bilesavar counties) as well as central part(Ardabil and Meshkinshahr counties) were of great importance in terms of the presence of Larroussius subgenus sand flies and the possibility of transmission of the visceral leishmaniasis.

黄河沉积砂对粉煤灰混凝土力学性能及耐久性能的影响研究

黄河三角洲区域长期累积产生的大量沉积砂,对下游地区的生态环境和防洪安全产生了恶劣影响。利用黄河沉积砂部分取代机制砂制备大体积粉煤灰混凝土,改善粉煤灰混凝土的宏观性能,对于减少环境污染、实现资源化利用具有重要意义。研究了黄河沉积砂不同取代率对大体积粉煤灰混凝土力学性能和耐久性能的影响。结果表明,随着黄河沉积砂取代率的增加,混凝土力学性能呈现先增加后降低的趋势,在10%取代率时强度达到最高,在20%取代率时能够达到天然骨料粉煤灰混凝土强度水平。同时,黄河沉积砂取代率超过20%时,粉煤灰混凝土的收缩率增加,相对动弹模量显著降低,过量的黄河沉积砂会对混凝土的抗收缩和抗冻性能产生负面影响,结果可为黄河沉积砂在粉煤灰混凝土中的应用提供理论依据和科学支撑。

Genetic variation of sand flies(Diptera:Psychodidae)in Gampaha and Kurunegala districts of Sri Lanka:Complementing the morphological identification

Objective:To identity the variation of sand flies in the Gampaha and Kurunegala districts of Sri Lanka and to assess DNA barcoding as a complementing method for morphological identification.Methods:A total of 38441 sand flies were collected from selected localities in Gampaha and Kurunegala districts using standard entomological techniques from May 2017 to December 2018.Specimens were identified using morphological features and compared with mitochondrial cytochrome C oxidase subunitⅠgene-based DNA barcoding as an alternative tool.Results:Morphological and molecular identification confirmed the presence of four species under two genera(Phlebotomus and Sergentomyia).Phlebotomus argentipes was the predominant species,followed by Sergentomyia(S.)punjabensis,S.babu insularis,and an unidentified Sergentomyia sp.Phlebotomus argentipes showed a clear genetic differentiation from other species.S.babu insularis and S.punjabensis showed a higher genetic affinity to each other than the unidentified species.The unidentified Sergentomyia species is morphologically similar to S.zeylanica,but differs only in clavate gonostyle.Conclusions:DNA barcoding is an effective technique for the identification of sand flies.Further studies using molecular techniques will improve the knowledge of the cryptic diversity of Sri Lankan sand fly fauna.Establishing a reliable and standardized identification system for sand fly species in Sri Lanka is recommended.

Optimization of green sand mould system using Taguchi based grey relational analysis

The strength of the mould cavity in sand casting is very much significant to attain high-quality castings. Optimization of green sand process parameters plays a vital role in minimizing casting defects. In the present research work, the effect of process parameters such as AFS grain fineness number, water, molasses, bentonite, fly ash, and ramming, and their levels on the resultant mould properties were investigated and optimized using Taguchi based grey relational analysis. The Taguchi L18 orthogonal array and analysis of variance(ANOVA) were used. The quality characteristics viz., green compression strength, permeability, bulk density, mould hardness and shatter index of green sand mould were optimized using grey relational grade, based on the experiments designed using Taguchi's Design of Experiments. ANOVA analysis indicated that water content is the most influential parameter followed by bentonite, and degree of ramming that contributes to the quality characteristics. The results are confirmed by calculating confidence intervals, which lies within the interval limits. Finally, microstructure observations and X-ray diffraction analysis have been performed for the optimal sand parametric combination. Results show that presence of maximum amount of SiO_2, which might be the reason for enhancement of the physical properties of the sand.

Distribution and ecological aspects of sand flies(Diptera:Psychodidae) species in Northeastern Iran

Objective:To determine both the distribution and the ecological characteristics of sand flies in Golestan Province,northeast of Iran in 2016.Methods:In this study,34 villages were selected based on their geographical conditions.Sticky paper traps were used for collecting the sand flies.Sampling was carried out in each of villages from May to November.In each village,60 traps for indoors and 60 for outdoors were monthly installed.The species of all collected sand flies were determined using approved morphological keys.Pearson coefficient correlation was used to find the relationship between the number of collected Phlebotomus papatasi from different villages and incidence rate of zoonotic cutaneous leishmaniasis as well as the number of positive cases of the disease.The altitude of the studied villages was extracted from digital elevation model of the area using GIS and vegetation cover density index of the province was extracted from Modis satellite imagery and distribution map of sand flies drown up.Results:Overall,5 428 sand flies were collected and identified,belonging to 18 species.Phlebotomus wenyoni was reported for the first time from the area in this study.The frequency of sand flies in the villages located in northeast of the Golestan province(the plateau area,lower altitude,arid and semi-arid climates,and lower vegetation cover density),were more than other villages in this province.There was a significant correlation between the number of collected Phlebotomus papatasi and incidence rate of the zoonotic cutaneous leishmaniasis cases in different villages(r=0.837,P=0.019) as well as the number of positive cases of the disease(r=0.688,P<0.001).Conclusions:In the northeaster areas of Golestan Province which is known as the endemic foci of zoonotic cutaneous leishmaniasis,the abundance of sand flies were more and the conditions for their growth and development were more appropriate.

Phenology and population dynamics of sand flies in a new focus of visceral leishmaniasis in Eastern Azarbaijan Province,North western of Iran

Objective:To investigate species composition,density,accumulated degree-day and diversity of sand flies during April to October 2010 in Azarshahr district,a new focus of visceral leishmaniasis in north western Iran.Methods:Sand flies were collected using sticky traps biweekly and were stored in 96%ethanol.All specimens were mounted in Puri’s medium for species identification using valid keys of sandflies.The density was calculated by the formula: number of specimens/m of sticky traps and number of specimens/ number of traps.Degree-day was calculated as follows:(Maximum temperature + Minimum temperature)/2—Minimum threshold.Diversity indices of the collected sand flies within different villages were estimated by the Shannon- weaver formula(H’=sum form(i=1) to s Pi log_e Pi ).Results:Totally 5 557 specimens comprising 16 Species(14 Phlebotomus,and 2 Sergentomyia) were indentified.The activity of the species extended from April to October.Common sand-flies in resting places were Phlebotomus papatasi, Phlebotomus sergenti and Phlebotomus mongolensis.The monthly average density was 37.6.41.1, 40.23,30.38 and 30.67 for Almalodash,Jaragil,Segaiesh,Amirdizaj and Germezgol villages, respectively.Accumulated degree-day from early January to late May was approximately 289 degree days.The minimum threshold temperature for calculating of accumulated degree-day was 17.32℃.According on the Shannon-weaver(H’),diversity of sand flies within area study were estimated as 0.917,1.867,1.339,1.673,and 1.562 in Almalodash,Jaragil,Segaiesh,Amirdizaj and Germezgol villages,respectively.Conclusions:This study is the first detailed research in terms of species composition,density,accumulated degree-day and diversity of sand flies in an endemic focus of visceral leishamaniasis in Azarshahr district.The population dynamics of sand flies in Azarshahr district were greatly affected by climatic factors.According to this study the highest activity of the collected sand fly species occurs at the teritary week of August.It could help health authorities to predicate period of maximum risk of visceral leishamaniasis transmission and implement control program.

Spatiotemporal Distribution of Phlebotomine Sand Flies （Diptera： Psychodidae） in a Focus of Cutaneous Leishmaniasis in Foum Jamaa （Azilal, Atlas of Morocco）

An entomological survey of Phlebotomine sand flies （Diptera： Psychodidae） was carried out in three sectors of Foum Jamgta region （province of Azilal, Morocco） during the year 2010. Morphological identification was performed on a total of 1,152 sand flies （23% females and 77% males） collected by sticky paper traps. 80% of the total collected flies were identified as Phlebotomus （Paraphlebotomus） sergenti （Parrot） （57%） and Phlebotomus （Larroussius） longicuspis （Nitzulescu） （23%）. In addition to these dominant species, four other species were found, Phlebotomus （Phlebotomus） papatasi （Scopoli）, Sergentomyia （Sergentomyia） minuta （Rondani）, Phlebotomus （Larroussius） perniciosus （Newstead） and Phlebotomus （Paraphlebotomus） chabaudi （Croset）. Overall, the population dynamics show a yearly bimodal pattern related to rainfall and temperature, and with high density around human dwellings. The spatiotemporal distribution of sand fly species was helpful to discuss strategies that might be useful in controlling cutaneous leishmaniasis transmission in this endemic focus.

沙漠砂混凝土与钢筋黏结性能试验研究

在我国西部沙漠砂资源丰富的背景下,探究沙漠砂对钢筋与混凝土黏结性能的影响,制作中心拉拔试验,通过对不同沙漠砂取代率和不同粉煤灰掺量下的钢筋与混凝土的黏结强度进行试验研究。根据黏结滑移曲线,分析沙漠砂取代率和粉煤灰掺量对钢筋和混凝土黏结强度、极限位移、破坏模式的影响。研究结果表明:直径16 mm钢筋混凝土试件在锚固长度较短导致脆性劈裂破坏的情况下,钢筋与混凝土的黏结强度随沙漠砂取代率的增加呈先上升后下降的趋势;粉煤灰掺量为20%时,对两者的黏结强度提升最大。

Sustainable Fly Ash Based Roof Tiles with Waste Polythene Fibre: An Experimental Study

The compressive stress-strain behavior and other characteristics of treated fly ash based roof tiles have been studied by several experimental tests. This paper attempts to presents the results and observations of a study and comparison based on the past reported experimental data. Based on the results and observations of the comprehensive experimental study, five “control points” have been identified. The new sets of experiment have been carried out to investigate whether it might be possible the use of fly ash in fly ash based roof tiles for residential construction. In the present study, treated fly ash (TFA) of C category was used with different materials as a replacement of clay for making treated fly ash stone dust roof tiles (TFASDRT). Treated fly ash stone dust roof tiles (TFASDRT) were studied at varying percentages of cement, coarse sand, and radish stone dust (RSD) along with the constant percentage of waste polythene fibre (WPF). A research program was undertaken to evaluate the suitability of such test for assessing the properties of treated fly ash stone dust roof tiles (TFASDRT). The result of this study recommends that the fly ash based roof tiles provides a sustainable supplement to the traditional clay roof tiles, they increase the efficiency of traditional roof tiles and significantly help to reduce the environmental issues associated with the disposal of these waste materials.

基体材料对铁路沿线风积沙ECC性能影响研究

为解决沙漠戈壁地区河砂资源紧缺、运输成本高等问题,同时减轻沙漠铁路风沙灾害,开展沙漠铁路沿线原状风积沙制备地域性工程水泥基复合材料(ECC)的试验研究。通过正交试验探究了不同风积沙掺量(S/C)、粉煤灰掺量(FA/C)和水胶比对ECC性能的影响,对三点弯曲试验的试件进行了开裂形态及荷载-挠度曲线的比较,并对流动度、表观密度、力学性能以及韧性进行了极差分析,结合微观分析初步确定出合理的基体配合比;在此基础上进一步探究了不同粉煤灰掺量对ECC抗压性能、弯曲性能、拉伸性能和变形能力的影响。研究结果表明:风积沙对流动度、弯曲性能影响最显著,粉煤灰对表观密度、抗压性能影响最显著;当风积沙掺量为0.75、粉煤灰掺量为1.50、水胶比为0.34时材料的综合性能最好,即流动度、抗压抗折强度分别为:151 mm、50.1 MPa和17.3 MPa;粉煤灰掺量从1.50增加到3.50时,材料极限拉应变在2%~3.5%范围内波动,掺量为2.50时极限拉应变出现最大值3.5%;当掺量为3.0时轴拉试件裂缝宽度最小为100μm,此时裂缝数量最多、间距最小。风积沙掺量为0.75、粉煤灰掺量为1.5时纤维表面有明显划痕且附着水化产物,纤维在基体中能较好地发挥桥联作用;水胶比为0.36时基体密实度较低,对纤维的锚固作用会被削弱。研究为风积沙在沙漠地区铁路工程中制备高延性混凝土提供了一定的理论依据。

黑水虻虫沙对矿区土壤中新银合欢与豌豆生长的影响

探究黑水虻虫沙作为一种有机肥料,以0%、5%、10%、20%和30%的比例与矿区土壤混合后,对新银合欢和豌豆的发芽和生长状况产生的影响.通过对比不同施肥处理下新银合欢和豌豆的发芽数量、株高及干重发现,添加20%黑水虻虫沙可显著促进新银合欢在矿区土壤中的生长,而对豌豆生长则产生了抑制效果.结果表明,黑水虻虫沙有潜力作为一种新型有机肥,有效改善新银合欢在矿区土壤中的生长条件;然而对于豌豆而言,黑水虻虫沙并不适合作为肥料使用.故需要进一步研究以确定豌豆适宜的土壤改良方法,以促进其在矿区土壤中的生长.

基于灰关联理论的混凝土抗压强度影响因素分析

基于灰色关联分析具备的发现系统中各因素对系统结果影响差别的特性,运用灰色关联分析方法,分析了粉煤灰掺量、砂率和水灰比等因素对混凝土抗压强度影响的显著程度。结果表明,粉煤灰掺量对混凝土抗压强度的影响最为显著,与实际实验结果基本一致。分析得出,灰关联分析方法具备一定的结果分析优势,对于现场混凝土试配具有较好的参考意义。

粉煤灰对高强混凝土力学性能及孔隙结构影响

为探究粉煤灰替代水泥比例对机制砂高强混凝土(MSC)和天然砂高强混凝土(NSC)的强度影响以及内部孔隙结构变化,设计粉煤灰替代水泥比例分别为0,10%,15%,20%和25%配制C80高强混凝土,借助核磁共振技术(NMR)分析混凝土孔隙演变规律,利用X射线衍射(XRD)、差热-热重综合仪、场发射扫描电镜(SEM)技术分析胶凝材料水化产物形态和微观形貌.结果表明:MSC工作性能略低于NSC,各龄期下MSC强度均高于NSC,前期强度随粉煤灰掺量的增加而降低,后期10%粉煤灰混凝土强度最高;10%粉煤灰促进水泥水化进程,填充凝胶孔隙,降低裂隙生成,从而优化混凝土内部结构孔隙,提升混凝土整体密实度;考虑细骨料形貌参数及粉煤灰掺量对混凝土强度的影响,基于可压缩堆积理论建立了粉煤灰混凝土28 d抗压强度预测模型,模型精度良好.研究可为粉煤灰高强混凝土高质量应用提供一定参考.

天然沙漠砂混凝土配合比优化研究

为充分利用新疆地区自然资源,达到“就地取材”“以灾制灾”的目的,采用天然沙漠砂替代混凝土骨料并在胶凝材料中加入粉煤灰、硅灰进行混凝土配合比优化研究。首先,通过正交试验,研究粉煤灰掺量、水胶比、灰砂比和减水剂掺量四个因素对沙漠砂混凝土性能的影响,结合天然沙漠砂混凝土抗压及劈裂抗拉强度进行了极差、因素指标和方差分析。随后,采用单因素试验法探究了硅灰掺量对天然沙漠砂混凝土力学性能和工作性能的影响。结果表明,天然沙漠砂混凝土最优配合比为粉煤灰掺量20%(质量分数,下同)、水灰比0.33、灰砂比1∶2、减水剂掺量0.8%。硅灰的加入能显著提升沙漠砂混凝土的抗压强度,但会降低沙漠砂混凝土的工作性能,加入10%硅灰时,沙漠砂混凝土的力学性能和工作性能最佳。

粉煤灰掺量对隧道机制砂喷射混凝土性能的影响

为了提高以机制砂为细骨料配制的喷射混凝土工作性能,同时进一步节约机制砂喷射混凝土的施工成本,本文以重庆渝湘高速公路复线彭水隧道施工为背景,在喷射混凝土胶凝材料中掺入适量的粉煤灰代替部分普通硅酸盐水泥,通过室内试验及现场试验对比分析开展粉煤灰掺量对机制砂喷射混凝土工作性能、抗压强度的影响,为粉煤灰在机制砂喷射混凝土中的应用提供参考。

冲击荷载下高强混凝土动力特性及破碎特征研究

为探究粉煤灰替代率和细集料类型对高强混凝土冲击压缩性能的影响,以粉煤灰替代水泥比例为0、10%、15%、20%、25%为胶凝材料,玄武岩机制砂和天然砂为细集料配制C80高强混凝土,利用分离式霍普金森杆对其开展冲击压缩试验,计算破碎体分形维数量化混凝土破碎特征,并借助扫描电镜(SEM)分析混凝土微观形貌。结果表明:机制砂混凝土(MSC)的峰值应力和韧性均高于天然砂混凝土(NSC);随着粉煤灰替代率增加,混凝土峰值应变逐渐降低;当粉煤灰替代率10%时,混凝土的峰值应力和韧性均达到最高值,且破碎体分形维数最小、平均块径最大、综合表现的破碎特征最简单;与未掺粉煤灰组混凝土相比,粉煤灰替代率10%时混凝土的微观形貌致密,孔隙数量减少,整体密实度提升。

基于响应面分析胶凝砂砾石材料渗透性能研究

为研究不同配合比对胶凝砂砾石渗透性能的影响,选取3个因素(粉煤灰掺量、水胶比、砂率),利用响应面法对试验结果进行影响因素的显著性分析,得出胶凝砂砾石渗透系数对单因素和两两因素交互作用的敏感程度。结果表明:粉煤灰、砂率对渗透系数呈现出极强敏感强度,水胶比对渗透系数敏感强度最低;另外因素之间的两两交互作用对渗透性能的影响从高到低依次为水胶比和砂率、粉煤灰和砂率、粉煤灰和水胶比;通过响应面数学模型得出最优配合比为粉煤灰掺量为22 kg/m^(3)、砂率为20%、水胶比为1.0。

水玻璃对粉煤灰海水海砂混凝土氯离子固化能力的影响

本研究以粉煤灰、海水和海砂为原料,制备了粉煤灰海水海砂混凝土,在模拟海水环境下测定了其总氯离子和自由氯离子含量,探讨了水玻璃掺量对粉煤灰海水海砂混凝土氯离子固化能力的影响。采用X射线衍射仪(XRD)、热分析(TG-DSC)、扫描电镜(SEM)等技术手段分析了海水海砂混凝土水化产物和微观形貌的变化。研究结果表明:随着水玻璃掺量的增加,氯离子固化能力呈现先增大后减小的趋势。当水玻璃掺入量为3%时,最大氯离子固化能力值可达到0.943。氯离子的固化主要来源于C-S-H凝胶的物理吸附和Friedel盐的化学结合作用。