The Economics of Competing Water Uses under a FERC Licensing Agreement: Estimation of Property Value, Recreation, and Hydroelectric Impacts

Reservoirs provide a variety of services with economic values across multiple sectors. As demands for reservoir services continue to grow and precipitation patterns evolve, it becomes ever more important to consider the integrated suite of values and tradeoffs that attend changes in water uses and availability. Section 316 (b) of the Clean Water Act requires that owners of certain water cooled power plants evaluate technologies and operational measures that can reduce their impacts to aquatic organisms. The studies must discuss the social costs and benefits of alternative technologies including cooling towers (79 Fed. Reg. 158, 48300 - 48439). Cooling towers achieve their effect through evaporation. This manuscript estimates the property value, recreation, and hydroelectric generation impacts that could result from the evaporative water loss associated with installing cooling towers at the McGuire Nuclear Generating Station (McGuire) located on Lake Norman, North Carolina. Although this study specifically evaluates the effects of evaporative water loss from cooling towers, its methods are applicable to estimating the economic benefits and costs of a new water user or reduced water input in any complex reservoir system that supports steam electric generation, hydroelectric generation, residential properties, recreation, irrigation, and municipal water use.

Recreational Behavior and Spatial Characteristics of Urban Parks Based on Multi-Source Information: A Case Study of Xiaohong Stone Carving Park in Nanjing

Urban parks are an important part of urban recreational spaces,and the development of analysis framework of recreational behavior and space is helpful for the design of urban parks to better meet the activity and usage requirements of visitors.In this paper,Xiaohong Stone Carving Park in Nanjing was taken as the research object to explore the relationship between landscape space and user behavior for design feedback.The orthographic image technology of unmanned aerial vehicle(UAV)and machine deep learning were used to analyze users behavior activities in the park,and the spatial characteristics of each node in the park were evaluated by semantic differential scale to explore the potential causes of behavior activities.The results showed that①there were significant differences in the number of visitors on holidays and working days,and young people and children were the main users.②The users activity of the park differed greatly on the inner and outer tour roads,and the users showed stronger willingness to stay on the inner tour roads.Recreational activities received more attention than cultural ones.③The overall distribution of users was significantly affected by hydrophilicity,and the recreational behavior and activity type were affected by multiple factors which include the hydrophilicity,safety,accessibility of cultural relics and the amount of recreational facilities.Finally,the enhanced strategies such as improving the cultural tour system,establishing hydrophilic safety belts and optimizing recreational facilities were put forward.

盆底超声检查和Green分型诊断产妇产后早期盆底结构及压力性尿失禁

目的:探究盆底超声检查和Green分型在产妇产后早期盆底结构及压力性尿失禁(SUI)诊断中的价值。方法:选取2021年3月-2023年3月本院就诊经产妇204例,根据产后早期(6~8周)SUI发生情况分为SUI组(82例)和非SUI组(122例)。检查产妇静息和Valsalva动作状态下膀胱颈距耻骨联合下缘的距离(BSD)、膀胱尿道后角(PUA)、膀胱颈移动度(BND)和尿道旋转角(UR),对比Green分型;采用受试者工作特征(ROC)曲线分析相关参数诊断SUI价值。结果:静息状态下,两组盆底超声参数无差异(P>0.05);SUI组Valsalva动作状态下的BSD、PUA、BND和UR值均大于非SUI组,Green分型Ι型占比(25.6%)低于非SUI组(59.8%)(均P<0.05)。ROC曲线分析,Green分型曲线下面积(AUC)0.579,对SUI诊断价值不佳(P=0.057),Valsalva动作状态下BSD(AUC=0.758)、PUA(AUC=0.743)、BND(AUC=0.769)和UR(AUC=0.705)对SUI诊断价值良好(均P<0.05)。结论:盆底超声检查和Green分型能有效评估经产妇早期盆底结构状况,前者可诊断SUI。

水禽细小病毒SYBR Green Ⅰ荧光定量PCR检测方法的建立与应用

为了建立水禽细小病毒(WPV)快速检测方法,根据序列比对结果在水禽细小病毒NS基因SF3保守区域内设计特异性引物,建立SYBR Green Ⅰ荧光定量PCR通用检测方法。该方法的扩增效率(E)为90.0%,相关系数(R~2)=0.99,标准曲线方程为y=-3.607x+38.77;除WPV出现S形扩增曲线外,新城疫病毒(NDV)、H9亚型禽流感病毒(H9 AIV)、鸭坦布苏病毒(DTMUV)、鸭肝炎病毒(DHAV)、鸭肠炎病毒(DEV)、鸭呼肠孤病毒(DRV)样品均未出现S形阳性扩增曲线;批内变异系数(CV)为0.15%~0.23%,批间变异系数为0.09%~0.28%。结果表明,SYBR Green Ⅰ荧光定量PCR检测方法重复性好、灵敏度高和特异性强。临床样品检测结果表明,SYBR Green Ⅰ荧光定量PCR与普通PCR的符合率达98.4%,灵敏度是普通PCR的1 000倍。SYBR Green Ⅰ荧光定量PCR检测方法不仅能定性检测WPV,还可以进行定量检测,可用于种鸭场、种鹅场的WPV净化检测,也可用于WPV临床大量样品的快速检测。

约束Green函数与非线性地基梁模态分析

在生物和医学领域,微机电系统(MEMS)中的微梁结构在植入人体的使用时,由于体内的细胞环境类似于水凝胶,在这种环境下工作,设备和仪器的精度和稳定性很大程度上受到细胞弹性的影响.为了分析此类地基梁的动力学问题,本文建立了非线性基础上的梁振动模型,研究了任意位置弹簧和非线性弹簧基础上的梁模态.通过Laplace变换和线性叠加原理,得到了一种约束Green函数,利用数值计算验证方案的有效性,并研究了各种重要物理参数的影响,发现弹簧位置向跨中移动时,模态对称性被打破,弹簧刚度增加,模态阶数改变.

美洲鳗鲡腺瘤病毒(AEAdoV)普通PCR和SYBR Green I实时荧光定量PCR检测方法的建立及应用

为建立美洲鳗鲡腺瘤病毒(AEAdoV)的检测方法,根据AEAdoV福建株(AEAdoVFJ)的superfamily 3 helicases(S3H)序列,设计引物,建立了AEAdoV的普通PCR和qPCR检测方法;进一步评价检测方法的灵敏性、特异性及重复性,利用2种方法对美洲鳗鲡“出血性烂鳃”病料进行了检测,并对美洲鳗鲡体内不同组织的病毒含量进行分析。结果显示,普通PCR扩增的目的片段长度约300 bp,利用其构建的qPCR质粒标准品,其拷贝数与qPCR阈值循环数(C_(t))线性关系良好,线性范围广,标准曲线相关系数(R2)达到0.999,扩增效率为105.067%。建立的普通PCR法和qPCR的最低检测AEAdoV拷贝数分别为100个和10个。2种方法均可特异性检测AEAdoV,而对蛙虹彩病毒(RGV)、鳗鲡疱疹病毒(AngHV)、鲤疱疹病毒(KHV)、对虾白斑综合征病毒(WSSV)、日本鳗鲡内皮细胞坏死病毒(JEAdoV)和花鳗鲡腺瘤病毒(MEAdoV)均无扩增反应。qPCR法的组内和组间变异系数均小于2%,表明其重复性良好。临床应用结果显示,35份美洲鳗鲡“出血性烂鳃”病料,采用普通PCR法的AEAdoV检出率为82.8%,而qPCR法的AEAdoV检出率为97%。对美洲鳗鲡不同组织的病毒含量分析结果显示,心脏、肝脏、鳃、鳍的AEAdoV相对含量较高,而黏液、皮肤和脾脏的病毒含量相对较低。研究表明,建立的AEAdoV的灵敏度高、特异性强的普通PCR和qPCR检测方法,证实AEAdoV与美洲鳗鲡“出血性烂鳃”病密切相关,且在感染鳗鲡主要组织中都存在。实验结果对于研究AEAdoV的致病性,开展其流行情况和病原学情况分析具有重要意义。

3型哺乳动物正呼肠孤病毒SYBR Green I荧光定量PCR方法的建立及应用

哺乳动物正呼肠孤病毒(MRV)是双链RNA病毒,可以感染自然宿主的哺乳动物和脊椎动物。为建立一种针对3型哺乳动物正呼肠孤病毒(MRV-3)的特异且快速的检测方法,本研究根据Genbank登录的MRV-3(OQ627746-OQ627755)S1基因保守区设计1对特异性引物,并从MRV-3中扩增S1基因,构建重组质粒p MD18-S1,经PCR和测序鉴定正确后作为质粒标准品,经反应体系及反应条件优化后首次初步建立了检测MRV-3的SYBR Green I荧光定量PCR(q PCR)方法。将质粒标准品10倍倍比稀释后作为模板经该q PCR扩增,建立标准曲线,结果显示,质粒标准品在1.3×10~8拷贝/μL~1.3×10~3拷贝/μL与各自的Ct值均呈良好的线性关系,斜率为-3.1706,R~2为0.9999,熔解曲线为单峰。以牛病毒性腹泻病毒(BVDV)、牛肠道病毒(BEV)、水牛匈爱病毒(Buf Hu V)、牛冠状病毒(BCo V)、牛细小病毒(BPV)和MRV-3的基因组DNA/c DNA为模板,利用本研究建立的q PCR方法检测,评估该方法的特异性;将质粒标准品10倍倍比稀释至1.3×10~2拷贝/μL~1.3×10~8拷贝/μL后作为模板,分别利用本研究建立的q PCR和常规PCR检测,比较两种方法的检测结果,评估本研究建立q PCR方法的敏感性;以1.3×10~3拷贝/μL~1.3×10~7拷贝/μL 5个不同浓度的质粒标准品为模板,利用该方法分别进行批内和批间的重复性试验,评估该方法的重复性。结果显示,该方法只能检测出MRV-3,其他相关病原的检测结果均为阴性;该q PCR对质粒标准品的检测限为1.3×10~3拷贝/μL,比常规PCR敏感性高10 000倍;批内和批间重复性试验的变异系数均小于或等于1.0%,表明该q PCR方法特异性强、敏感性高、重复性好。利用该方法检测220份牛粪便样品,结果显示MRV-3的检出率(3.64%,8/220)高于常规PCR的检出率(1.36%,3/220),两种检测方法的阳性符合率达100%,阴性符合率为97.75%,总符合率为97.78%。综上所述,本研究首次建立的检测MRV-3的SYBR Green I q PCR方法可以用于临床牛腹泻病原的检测,为MRV-3尤其是牛源MRV-3提供了一种快速灵敏的检测手段,也为MRV-3的后续研究奠定了基础。

猪流行性腹泻病毒SYBR Green I实时荧光定量PCR检测方法的建立

为了建立高效、灵敏的猪流行性腹泻病毒(PEDV)检测方法,本研究从GenBank数据库中获取PEDV N基因序列,扩增出PEDV N基因标准质粒,并在N基因的保守区域内设计了一对特异性荧光定量引物,成功建立了SYBR Green I实时荧光定量PCR检测方法。经过一系列试验表明,该检测方法线性关系良好,R^(2)值为0.99;特异性强,敏感性高,最低可检测至2.23 copies/μL,比普通PCR灵敏约100倍;重复性好,组内变异系数为0.25%~0.43%,组间变异系数为0.67%~0.97%;对于各地区96份临床样品检测出PEDV阳性率为25%。本研究建立的实时荧光定量PCR检测方法为PEDV的临床诊断、流行病学调查以及定量研究提供了有效的检测工具。

三疣梭子蟹十足目虹彩病毒1 SYBR Green I荧光定量PCR检测方法的建立及初步应用

为建立十足目虹彩病毒1(decapod iridescent virus 1,DIV1)的SYBR GreenⅠ荧光定量PCR检测方法,根据DIV1的MCP和ATPase基因序列,设计并筛选出引物,以制备的DIV1阳性质粒标准品为模板构建标准曲线,建立DIV1的SYBR Green I qPCR方法,并对该方法进行临床初步应用。结果显示,建立的qPCR方法阈值循环数(cycle threshold value,Ct)与标准品拷贝数的对数线性关系良好,标准曲线相关系数(R^(2))为0.999;对DIV1阳性的虾蟹核酸样本能够进行特异性扩增,但对传染性脾肾坏死病毒(infectious spleen and kidney necrosis virus,ISKNV)和白斑综合征病毒(white spot syndrome virus,WSSV)阳性核酸样本均无扩增;最低检测限为9.77 copies/μL;Ct值的组内和组间变异系数均小于1%。运用该方法对70份疑似感染DIV1的虾蟹类样本进行DIV1检测,该方法阳性率为48.57%,与套式PCR检测方法的阳性率一致;利用建立的方法对DIV1阳性三疣梭子蟹的血淋巴、肝胰腺及心脏等组织进行定量检测分析,结果显示各组织中均存在DIV1,其中血淋巴中DIV1平均拷贝数最高。研究表明,建立的SYBR GreenⅠ荧光定量PCR方法特异性强、灵敏度高、重复性好,可用于对DIV1的快速、定量检测,对十足目虹彩病毒病的诊断和防控具有重要意义。

香辛料SYBR GREENⅠ染料实时聚合酶链式反应检测方法的建立及应用

目的:本研究致力于建立香辛料真实性成分的分子鉴定方法,为香辛料的掺假提供有效的鉴定和检测方法,在不同的使用条件下分别实现定性或半定量分析,为建立相关标准提供一定的基础技术支撑。方法:研究采用SYBR GREENⅠ染料实时聚合酶链式反应(polymerase chain reaction,PCR)方法,通过设计特异性引物成功建立了特异性检测八角、茴香、胡椒和花椒的分析技术。结果:该方法能够特异性检测出八角、茴香、胡椒、花椒,Ct值在标准品体积分数0.001%~10%范围内线性关系良好。针对八角标准品,检测限为1%;针对茴香、花椒、胡椒标准品,最检测限均为0.001%。利用该方法对5份实际样本进行检测,分别在样本1中未检测出八角、茴香、胡椒、花椒;样本2、3、5中检测出八角、茴香、胡椒;样本4中检测出八角、茴香、胡椒、花椒。结论:本实验建立的SYBR GREENⅠ染料实时PCR方法灵敏度高、重复性好,可应用于实际样品的检测。

SYBR GreenⅠ染料-实时荧光定量聚合酶链式反应法检测发酵乳中的霉菌和酵母含量

目的建立一种应用SYBR GreenⅠ染料的实时荧光定量聚合酶链式反应法快速检测发酵乳中的霉菌和酵母菌。方法本研究针对霉菌与酵母菌的保守序列设计引物,确定最优反应体系与反应条件。通过熔解曲线以及非目标菌株的检测验证该方法的特异性;通过菌悬液的梯度稀释检测确定该方法的灵敏度;通过菌悬液与发酵乳样品混合后进行检测,确定该方法的检出限,并得到标准曲线。结果该方法能够特异性的检测发酵乳中的霉菌、酵母菌,无交叉反应。该方法检测霉菌、酵母菌的灵敏度均为10^(2) CFU/mL,并且当菌悬液与发酵乳样品混合后,并没有降低该方法的检出限。在10^(2)~10^(6) CFU/mL浓度范围内,菌液浓度的对数值与循环阈值(cyclethreshold,Ct)具有良好的线性关系,可以在市售样品的检测中通过Ct值计算样品中目标菌的含量,更快的判断发酵乳是否被霉菌、酵母菌污染。结论该方法可用于发酵乳中霉菌和酵母菌的快速检测,为发酵乳的食品安全提供了技术保障。

Evaluation of Recreation Service Quality of Slow Traffic Space in Urban Parks Based on IPA-Space Syntax Model

To build an“ecological and livable city”,it is important to figure out the relationship between human activity and urban park space and create a high-quality urban park through the integration of“people”and“park”.Taking Longhu Park in Huainan Province as an example,the study quantitatively analyzed and evaluated the characteristics and service quality of slow traffic space using importance-performance analysis(IPA)and space syntax,clarified the key indexes and areas to be optimized,and put forward corresponding design countermeasures and suggestions in combination with human activity demand.The results suggest that:①The mean performance of park recreation service quality is 3.63,less than the mean importance(3.95).Tourists pay special attention to the safety and convenience of slow traffic space,and the diversity and identiability of site functions is the focus“to be improved”.②The accessibility of Longhu Park shows a strong irregular shape in the southwest.The dead-end roads in the far lake area and the flora and fauna area on the northwest side have weak spatial perception,and the composite function carrying potential of slow traffic space is better reflected in a small range.Therefore,an optimization strategy for slow traffic space is proposed to enhance the continuity of road network,site identifiability,and functional diversification.The results will provide new thoughts of governance based on spatial humanism for the high-quality renewal of urban parks in the new era.

鸡圆环病毒SYBR GreenⅠ实时荧光定量PCR检测方法的建立

为快速准确检测鸡圆环病毒(CCV),试验根据CCV Rep基因设计特异性引物,以CCV阳性病料提取的DNA为模板进行PCR扩增,构建CCV重组质粒,建立检测CCV的SYBR GreenⅠ实时荧光定量PCR方法。结果显示:试验建立的方法对2.87×10^(8)~2.87×10^(1)copies/μL浓度范围的CCV重组质粒标准品呈现良好的线性关系,相关系数(R^(2))为0.9936,灵敏度比常规PCR高100倍;该方法对鸡传染性贫血病毒、新城疫病毒、传染性支气管炎病毒等常见鸡病毒性病原以及多杀性巴氏杆菌、禽致病性大肠杆菌、鸡白痢沙门氏菌无特异性扩增,批内和批间变异系数均不超过1%;该方法对60份疑似CCV感染临床样品检测结果显示,CCV阳性检出率(16.67%)高于常规PCR。上述结果表明,研究建立的CCV SYBR GreenⅠ实时荧光定量PCR方法具有良好的敏感性、特异性和重复性,检出限为2.87×10^(1)copies/μL,可以用于CCV的快速定量检测。

Laparoscopic left hemihepatectomy guided by indocyanine green fluorescence: A cranial-dorsal approach

BACKGROUND Advancements in laparoscopic technology and a deeper understanding of intra-hepatic anatomy have led to the establishment of more precise laparoscopic hepatectomy(LH)techniques.The indocyanine green(ICG)fluorescence navi-gation technique has emerged as the most effective method for identifying hepatic regions,potentially overcoming the limitations of LH.While laparoscopic left hemihepatectomy(LLH)is a standardized procedure,there is a need for innova-tive strategies to enhance its outcomes.important anatomical markers,surgical skills,and ICG staining methods.METHODS Thirty-seven patients who underwent ICG fluorescence-guided LLH at Qujing Second People's Hospital between January 2019 and February 2022 were retrospectively analyzed.The cranial-dorsal approach was performed which involves dissecting the left hepatic vein cephalad,isolating the Arantius ligament,exposing the middle hepatic vein,and dissecting the parenchyma from the dorsal to the foot in order to complete the anatomical LLH.The surgical methods,as well as intra-and post-surgical data,were recorded and analyzed.Our hospital’s Medical Ethics Committee approved this study(Ethical review:2022-019-01).RESULTS Intraoperative blood loss during LLH was 335.68±99.869 mL and the rates of transfusion and conversion to laparotomy were 13.5%and 0%,respectively.The overall incidence of complications throughout the follow-up(median of 18 months;range 1-36 months)was 21.6%.No mortality or severe complications(level IV)were reported.CONCLUSION LLH has the potential to become a novel,standardized approach that can effectively,safely,and simply expose the middle hepatic vein and meet the requirements of precision surgery.

和美乡村视角下的苏南农田“GREEN”水环境治理模式应用研究

随着中国宜居宜业和美乡村建设的不断深入,乡村水环境的治理与保护作为乡村生态文明建设的重要组成部分日益受到社会的重视和关注。在以往大规模灰色基础设施建设的背景下,乡村忽略了对于水生态绿色基础设施的构建,生态格局趋于破碎。农田空间作为农业面源污染的重要源头,结合多学科视角探索农田水环境污染治理新模式具有高度的必要性。立足于苏南地区独特的农田水网体系,紧密结合农业空间生产属性,研究现有农田水环境治理理论方法与实际建设,提炼以“源头绿色—过程净化—末端吸收—生态保育—循环回用”的苏南农田“GREEN”水环境治理模式,探索风景园林学科水治理方法在农田沟渠、河道及湿地等乡村空间的运用路径,并以常州市中天黄金大农场总体规划为例进行实践应用。推动风景园林学科于乡村生产空间的应用模式探索,为未来农业面源污染防治提供参考借鉴。

Does Green Food Certification promote agri-food export quality?Evidence from China

The construction of a food certification system plays a vital role in upgrading export quality, which previous studies have largely overlooked. We match China's industry-level data of Green Food Certification with its HS6-digit export data of agri-food products to quantify the impact of Green Food Certification on export quality. We identify the significant and positive effect of Green Food Certification on export quality. The 2SLS estimation based on instrumental variables and a range of robustness checks confirm the validity and robustness of the benchmark conclusions. Further analysis discloses that Green Food Certification improves export quality by raising agricultural production efficiency and brand premiums. Heterogeneity analysis shows that the effect of Green Food Certification varies across regions, notably improving the quality of agri-food products exported to developed regions and regions with high levels of import supervision. Furthermore, among various product types, Green Food Certification significantly improves the export quality of primary products and products vulnerable to non-tariff measures. The above findings could guide the future development of agri-food quality certification systems, potentially leading to a transformation and promotion of the agri-food trade.

Butterfly taxonomic and functional diversity in the urban green spaces of Hefei city

Urbanization has profound impacts on ecological environments.Green spaces are a vital component of urban ecosystems and play a crucial role in maintaining ecologi-cal balance and enhancing sustainability.This study aimed to investigate the community composition characteristics of butterflies in urban green spaces within the context of rapid urbanization.Simultaneously,it explored the status and dif-ferences in butterfly taxonomic diversity,functional diver-sity,and functional traits among different types of urban green spaces,regions,and urban gradients to provide rel-evant insights for further improving urban green space qual-ity and promoting biodiversity conservation.We conducted a year-long survey of 80 green spaces across different urban Project funding:This work was funded by the National Non Profit Research Institutions of the Chinese Academy of Forestry(CAFYBB2020ZB008),National Natural Science Foundation of China(32371936),and the Research Projects in Anhui Universities in 2022(n atural sciences)(2022AH051874).regions and ring roads within Hefei City,Anhui Province,with monthly sampling intervals over 187 transects.A total of 4822 butterflies,belonging to 5 families,17 subfamilies,40 genera,and 55 species were identified.The species rich-ness,Shannon,Simpson,functional richness,and Rao’s quadratic entropy indices of butterflies in urban park green spaces were all significantly higher than those in residential and street green spaces(P<0.05).Differences in butterfly diversity and functional traits among different urban regions and ring roads were relatively minor,and small-sized,multi-voltine,and long flying duration butterflies dominated urban green spaces.Overall,these spaces offer more favorable hab-itats for butterflies.However,some residential green spaces and street green spaces demonstrate potential for butterfly conservation.

Effect of a Commercial Extract of Green Tea and a Pure Catechin on Two Veillonella strains

The catechin Epigallocatechin-3-O-Gallate (EGCG) which is found in of Green Tea extracts (GTE), displays a variety of microbicidal properties. It is largely believed that EGCG inhibits the growth of cariogenic and periodontopathic bacteria. Objective: In this paper we compared the inhibitory activity of EGCG and a commercial GTE on the growth of Veillonella parvula. Chlorhexidine was used as positive control. Methodology: V. parvula ATCC 10790 and a clinical isolate obtained from a periodontal disease patient were cultured in the presence of EGCG or a commercial GTE, and the measurements of bacterial growth inhibition were compared to the values obtained with 0.12 and 0.2% chlorhexidine. Results: Chlorhexidine inhibited bacterial growth, however in contrast to a previous report, neither EGCG nor the GTE showed any effect on bacterial growth. Conclusions: The data show and confirm that chlorhexidine is a growth inhibitor of V. parvula while EGCG and GTE do not display such effect.

Tourists’Willingness to Pay for Recreation Services in Nyerere National Park,Tanzania:Are We Overvaluing or Undervaluing Our Nature Recreation Resources?

This study estimated tourists’Willingness to Pay(WTP)per day for recreation services in Nyerere National Park(NNP)and compared these values with daily travel costs that are incurred by tourists to visit NNP in order to inform whether recreation resources in the park are overvalued or undervalued.The study revealed that tourists’WTP per day for recreation services was estimated at$237.4 and$1521 for resident and non-resident tourists,respectively.The estimated tourists’WTP values exceed the daily travel costs currently incurred by tourists,which are$201.04 and$1517.97 for resident and non-resident tourists,respectively.This indicates that tourists are willing to spend more to enjoy recreation services in NNP,which signifies that recreation resources in NNP are slightly undervalued.In addi­tion,the findings disclosed that the largest share of tourist daily travel expenses is allocated to transportation services,and very little is paid to the park as a conservation fee.It was revealed that out of the daily travel expenses incurred by non-resident and resident tourists,only 4.62%and 2.23%are respectively paid directly to NNP as conservation fees.This study considers that allocation is not very fair;thus,NNP,in collaboration with TANAPA,needs to adjust the current entrance or conservation fee and reduce the transportation costs charged by tourist companies.The travel costs incurred by tourists,age,education,monthly income,site visited,substitute site,and quality of park were identified as significant factors in influencing tourists’WTP for recreation services in NNP.Thus,policies oriented to reduce tour­ists’transportation costs and improve the quality of national parks would attract more tourists to NNP.

Green Synthesis of Iron(Ⅱ,Ⅲ)-polyphenol Nanoparticles and Their Adsorption of Malachite Green

Three kinds of iron nanoparticles(FeNPs)were prepared via green route based on pomegranate(PG),green tea(GT),and mulberry(ML)extracts under ambient conditions.The obtained materials were characterized by scanning electron microscopy(SEM),transmission electronic microscopy(TEM),X-ray energy-dispersive spectrometer(EDS),X-ray diffraction(XRD),fourier transform infrared spectroscopy(FTIR),and X-ray photoelectron spectroscopy(XPS)techniques.The experimental results show that FeNPs were in the form of amorphous iron(Ⅱ,Ⅲ)-polyphenol complex with different dispersity and morphologies.GT-Fe has the smallest size range of 25-35 nm,PG-Fe has a moderate size-distribution of 30-40 nm,while ML-Fe formed a tuberous net-type with a sheeting structure.PG-Fe displays the highest removal efficiency of 90.2%in 20 min towards cationic dye of malachite green(16.6%by ML-Fe and 69.3%by GT-Fe),which is attributed to its highest polyphenol content,lowest zeta potential,as well as the most Fe^(2+)on the surface of FeNPs.The removal mechanism was mainly induced by electrostatic adsorption based on pH and zeta potential tests.