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英语作文对比评价语Title: Comparative Evaluation of English Essays。
In the realm of English composition, assessing and contrasting essays involves a meticulous examination of various aspects such as structure, coherence, language proficiency, and argumentative prowess. This comparative evaluation aims to dissect two distinct essays without divulging the prompt provided.Essay A。
Strengths:1. Structural Coherence: Essay A demonstrates a clear and logical structure, with each paragraph seamlessly transitioning to the next. The introduction sets the stage by providing context and a succinct thesis statement, followed by well-developed body paragraphs that support the main argument. The conclusion effectively summarizes keypoints without introducing new information.2. Language Proficiency: The language used in Essay A is sophisticated and appropriate for the intended audience. The writer employs a diverse vocabulary, varied sentence structures, and precise terminology to convey ideas effectively. Moreover, the essay showcases a strong command of grammar and mechanics, enhancing readability.3. Argumentative Depth: This essay excels in presentinga nuanced argument supported by relevant evidence and analysis. Each claim is substantiated with examples, quotations, or data, demonstrating thorough research and critical thinking skills. Additionally, the writer anticipates counterarguments and addresses them thoughtfully, further strengthening the overall argumentative framework.Weaknesses:1. Lack of Originality: While Essay A effectively synthesizes existing research and opinions, it lacksoriginal insights or unique perspectives. The arguments presented are somewhat conventional and fail to offer innovative solutions or fresh interpretations of the topic.2. Limited Engagement: Despite its coherent structure and well-developed arguments, Essay A could benefit from deeper engagement with opposing viewpoints or alternative perspectives. The writer tends to prioritize supporting evidence that aligns with their thesis, potentially overlooking contradictory evidence that could enrich the discourse.Essay B。
CURRICULUM VITAEFIRST NAME: MasoumehFAMILY NAME:AlbooghobeishGENDER:FemaleNATIONALITY:IranianADDRESS:No. 43, Anesthesiology Department, First Floor, ParamedicalSchool, Ahwaz Jundishapur University of Medical Sciences ,Ahwaz, Iran.E-mail:******************PHONE NUMBER:0098-611-3791698PLACE OF BIRTH:Abadan, IranMARITAL STATUS:MarridEDUCATION2005- 2006 Ph.D.Student in Delhi University, India.1989-1992Received Master of Sciences in Anesthesia from Shiraz MedicalSciences University, Shiraz, Iran, Feb. 1992.1986-1989 Received Bachelor in Nursing from Shiraz Medical SciencesUniversity, Shiraz, Iran, Feb.1989.1983-1986 Received Associate of sciences in Nursing from Shiraz MedicalSciences University, Shiraz, July 1986.Special Courses:1.A course of instructions in Acupuncture.2. Iranian Traditional Medicine Workshop.3. Recearch Methods Workshop.4. Teaching Methods Workshop.5. Writing Articles Workshop.6. Curriculum Planning Workshop.7. Problem Base Learning Workshop.8. Questionnaire Design Workshop.9. Introductory Medical Education Workshop.10. Teaching Plan Workshop.11. Student Assessment Workshop.12. Time Management Workshop.13. Medical Article Writing Workshop.14. Feed Back to Students (Educational Workshop)15. Counsel Professor Educational Workshop.16. Education Principles & Right Behavior with Children Workshop.17. Internal Assessment (Educational Workshop)18. Internal Assessment of Internal Department Workshop.EXPERIENCE2007 to date Lecturer and Head of Department of Anesthesiology in ParamedicalSciences School,Ahwaz Jondishapur University of MedicalSciences,Ahwaz, Iran.2001-2007Lecturer at Anesthesia Department, Paramedical Sciences School,Ahwaz Jondishapur University of Medical Sciences,Ahwaz, Iran.1993-2001Lecturer and Dean of educational&research affairs,Abadan Nursing School, Ahwaz Jondishapur University of MedicalSciences,Abadan, Iran.1992-1993As a Nurse Anesthesia at Shahid beheshti Hospital,Abadan, Iran.THACHING SUBJECTSPRACTICAL COURCES:1.The training of methods of anesthesia.2.The training of methods of working in operation room.3.The training of community health nursing (2)&(3).4.The training of medical –surgical nursing (1).5.The training in the field (internship) of community health nursing (2) & (3).6.The training in the field (internship) of medical –surgical nursing.7.The training of fundamental nursingTHEORITICAL COURCES:1.Basic of Anesthesia.2.Intensive Care Principles.3.Principles and routes of management in pain.4.Medical Terminology.5.English for Anesthesia.6.Nursing Principles & Working in Operation Room.7.Medical –Surgical Diseases Nursing (Respiratory Diseases).8.Individual Health (personal Health).9.Methods of Anesthesia(2)TITLE OF RESEARCHS1.Survey of environmental health in operation rooms in Abadan's hospitals.2. Pervalence rate of nosocomial infection in operation rooms in Abadan's hospitals.3. Effectiveness of face –to face teaching in rate of using contraceptive instruments, Zolfaghary area,Abadan.4. Need of blood transfusion in cesarean section.5. Survey of compliance with hand hygiene in ICU health care workers.6. Comparative evaluation of the effect of Acupuncture and Metoclopramide on the postoperative nauseaand vomiting in Gynecological laparoscopy.7. Visible and occult blood prevalence on anesthesia and monitoring equipment in operation room8. Comparison of BP variation in patient under spinal and general anesthesia in PACU.。
The contemporary cement cycle of the United StatesIntroductionHydraulic cement is one of the most important construction materials in modern society in terms of both value and volume. Portland cement, the most common type of hydraulic cement, is produced by heating limestone and other raw materials in a rotary kiln to produce an intermediate product called clinker. The clinker is then ground, along with about 5% (by weight) of gypsum, into a fine powder. When combined with water, cement forms a paste that binds sand and gravel (or other coarse aggregates) into a solid compound material known as concrete. Concrete usually contains about 11%–14% by weight of (dry) cement powder. Concrete is the most widely used manufactured material in buildings, bridges, streets, and highways.Cement production, especially to form clinker, is highly energy intensive；in the United States the average unit energy consumption for cement plants in 2000 was about 5.2 GJ per metric ton of cement. The critical environmental concerns associated with cement production are the large amount of raw materials required to make clinker, and the particulate and gaseous emissions (especially carbon dioxide which is a major greenhouse gas) from the clinker kilns. With respect to carbon dioxide, the cement industry is one of the two largest manufacturing industry sources in the United States, the other being the iron and steel industry.Concrete use in the United States reflects population growth and urbanization trends. Much of the concrete in use today (within buildings, roads, bridges, and other infrastructure) was installed several decades ago during early phases of growth and urbanization, and there are growing concerns about the condition and performance of this concrete. Various categories of infrastructure in the United States scored an overall grade of D (i.e., poor) in a recent assessment, and it was estimated that necessary replacement, rehabilitation, or both of infrastructure will require an investment of US$1.6 trillion by 2010.This work wil increase demand for cement. Apart from the environmental issues related to producing this extra cement, repair, replacement, or both of deteriorated infrastructure also commonly results in societal inconveniences and secondary environmental effects. For example, repair of transportation infra structure commonly causes delays and detours for vehicular traffic that may lead to greater fuel use and increased vehicular exhaust.To enhance the performance of concrete infrastructure in the United States and reduce environmental and economic impacts associated with deteriorating infrastructure, efforts are underway to develop advanced composite materials or concretes with greater strength and durability. A comparative evaluation of life-cycle costs and environmental management issues for conventional concrete and alternative materials can aid in the selection of the best building materials for repairing or replacing existing infrastructure. Material flow analysis of the cement cycle is a critical c omponent of such a comparative assessment and provides an understanding of resource supply, use, recovery, and recycling at a regional or national scale. Cement is chosen for the direct analysis instead of concrete itself because data on cement production and use are far more abundant and complete than those for concrete.This article undertakes a preliminary material flow anaysis of the contemporary cement cycle of the United State The objective is to characterize stocks and flows of cement(as a proxy for concrete) over its life cycle and to analyze the underlying environmental and resource use implictions. Material flow analysis is based on the universalla of mass conservation and is used to assess the current an future state of material flows and accumulation in the economy and in the environment. Many examples of material flow analysis models can be found in the literature.The present study is a component of the National Science Foundation MUSES Sustainable Concrete Infrastructure Materials and Systems project at the Center for Sustainable Systems, University of Michigan. This study provides an assessment of the flows of cement in the United States over the complete life cycle as characterized by three stages：production, use, and end-of-life disposal (see below for a detailed description of each life cycle stage). The intended purpose of this study to quantify cement flows is to understand the type and amount of raw materials extracted and consumed to produce cement and to estimate how much cement is added as new in-use stock every year, how much is discarded, and how much is disposed of in landfills. Previous material flow studies analyzing cement flows in the United Stateshave mainly focused on production-relatedflows, whereas this study provides a more integrated assess-ment, emphasizing the material flows for cement at the “end of life” of infrastructure systems.Production of cementRaw materials for the manufacture of cement are selected to provide the compositional requirements for modern portland cement clinker. Clinker is composed mainly of four oxides：calcium oxide (CaO – about 65% by weight), silica (SiO2 – about 22%), alumina (Al2O3 – about 6%), and iron oxide (Fe2O3 – about 3%). Raw materials for cement manufacture are mostly products from the mining industry. The calcium oxide is provided mostly by calcareous rocks such as limestone and marble. The alumina and silica are commonly provided by clay or shale；iron oxide by shale, iron ore, or mill scale；and silica sand is commonly used to remedy any remaining silica shortfalls in the other raw materials. Increasingly, industrial by-products such as ferrous slag and coal combustion fly ash are also being used as raw materials. The contemporary nonfuel raw materials consumption for the manufacture of cement and clinker in the United States is summarized in Table 1. Although Table does not distinguish between raw materials used to make clinker and those used subsequently in the finish mill to make finished cement, overall, about 1.7 metric tons of raw materials are required to produce 1 metric ton of clinker or portland cement. The majority of the apparent loss in mass is due to the emission of carbon dioxide, as will be discussed later. Not shown in Table 1 is the fact that about 0.2 metric tons of (mainly fossil) fuels are consumed per metric ton of clinker manufactured. Overall, cement manufacture also consumes about 100–160 kWh of electricity per metric ton of cement；in the United States, the vast majority of this electricity is purchased from the national grid.To minimize transportation costs, cement plants are generally located close to their limestone quarries. The limestone is transported from the quarry to the mill of the cement plant, where it is crushed and ground and then proportioned and mixed with vari ous other ground raw materials (as needed) to form the raw mix or feed for the kiln. At the high temperatures reached in the kiln, the rawmaterials react to produce several cement minerals, chiefly tricalcium silicate and dicalcium silicate, within a semifused nodular intermediate product called clinker.From an environmental standpoint, and that of the mass balance, the key reaction in the kiln is the highly energy intensive calcination (typically at about 750°–1000°C) break-down of the calcium carbonate (CaCO3) in the limestone to form calcium oxide (CaO) plus carbon dioxide (CO2). The subsequent formation of the actual clinker minerals and the clinker nodules typically requires yet higher temperatures, but the reactions actually require less thermal energy than does calcination, and there is little further change to the mass balance.The resulting clinker is interground with gypsum in the finishing mill to produce portland cement；the gypsum is added to control the setting rate of the concrete during cement hydration. More detailed descriptions of cement manufacture are given in the literature.In order to improve the performance of concrete and, increasingly, to minimize the environmental impacts of the manufacture of concrete, supplementary cementitious ma terials (SCM), such as fly ash, ground granulated blast furnace slag, silica fume, and pozzolana (a reactive volcanic ash), may be substituted for some of the portland cement in the finished cement (i.e., to make a blended cement) or in concrete. The extent to which SCM can substitute for portland cement depends mainly on the desired strength, durability, and other properties of the concrete, but substi-tution rates of 10%–30% or more are common. Apart from potentially improving the quality of the concrete, reducing the portland cement component of the concrete through incorporation of industrial by-products (fly ash and slag) as SCM also reduces the demand for virgin raw materials and the emissions associated with a given volume or mass of concrete. Likewise, the use of industrial by-product SCM in concrete decreases the need for disposal of these by-products, which conserves landfill space.Use of cementMost of the cement produced in the United States is portland cement (approximately 87 million metric tons per year). Portland cement is primarily utilized to make concrete, which has a wide spectrum of uses, including construction storage tanks. Compared to that of portland cement, the cement is primarily used in the construction of buildings. Detailed cement usage data are available only from the United States Geological Survey (USGS)and from the Portland Cement Association (PCA)；the former provides data on the distribution of portland cement shipments to different customer types, and the latter provides data on the end uses of cement. During the period 2000–2004, approximately 90% of portland cement shipments were made to ready-mixed concrete and concrete product producers, The data from the PCA averaged over the period 2000–2004 show that the cement end-use market was dominated by buildings (residential – 33%, commercial – 7%, public – 8%, and industrial – 4%) and streets and highways (29%), followed by water and waste management (6%) and other miscellaneous uses (12%).End-of-life management of cementConcrete in each of its uses has a certain useful lifespan. For example, streets and highways in the United States are expected to last 45 years, whereas residential buildings have an average lifetime of 80 years. The difference reflects thefact that streets and highways deteriorate more rapidly owing to their high degree of environmental exposure (to moisture, freezing and thawing, and chemicals such salt and sulfate) and the exposure to vehicular traffic. During the lifespan of each concrete structure, there are typically several cycles of repair and renovation. At their end of life, concrete structures are usually demolished. The further reuse of concrete construction and demolition debris depends on a number of factors such as its physical characteristics (porosity, density), the economic viability, and construction and material standards. The average material composition of construction and demolition debris fraction is higher in nonresidential buildings because the wall material in many of the residential bu ildings in the United States is not concrete. The amount of concrete debris from construction of new buildings is low because the amount of concrete to be poured is usually closely estimated using standard mix designs, and the amount of losses onsite are relatively small.In terms of reuse, it is more difficult to recover and recycle individual C&D materials from the demolition of buildings than from streets and highways because the debris from buildings is more heterogeneous. There are a number of advantages of in-place recycling of crushed concrete aggregate at highway sites, and a number of States in the United States are promoting such recycling. The reuse of crushed concrete aggregate from the existing pavement simplifies construction of new pavement at existing grade on highways. However,the specifications for construction materials do not promote reuse of materials already in use in the infrastructure.The concepts of material flow analysis were used to construct the contemporary cement cycle. The spatial boundary chosen for this study was the United States excluding Puerto Rico (so as to maintain data consistency as per USGS data). For the cement cycle, annual flow magnitudes for the production reservoir were averaged for the period 2000–2004 (data for use and end-of-life reservoirs are for 2002). The net cement flow can also be called the apparent consumption of cement. The flows to and from the production reservoir were broken down to three subreservoirs (mine mill complex, kiln, and finishing mill) to characterize the production and net trade (= import–export) flows of raw materials, clinker, and cement. Within the production reservoir, there could be net depletion or addition of material to clinker and cement stockpiles, depending on changes in inventory over the calendar year.Production residues consist of mine overburden (generally minor)；crushed limestone screenings (also known as stone dust or fines and are commonly used as a raw material for clinker production)；cement kiln dust (CKD)；carbon dioxide emissions from the calcination phase of the clinker production process；and other, volumetrically lesser, amounts of gaseous emissions from the kiln such as nitrogen oxides, sulfur oxides, and water vapor. In addition, there are carbon dioxide emissions from fuel combustion during clinker production. Mine overburden is the material moved during the extraction of the cement raw materials that is not used either for cement manufacture or for other purposes (e.g., sold as aggregates). Rock fines are materia l that passes through the smallest screen used in the raw materials processing circuits；of issue here are any fines not used as a raw material. CKD comprises fine particulate matter or dust that is generated in the kiln line；the material is essentially captured, but it may or may not be recycled to the kiln. If CKD is not recycled, it is generally land filled, although it can be used as a soil liming agent or as a fill material.This material flow analysis accounts for the flows and transformation of only the nonfuel materials used to make clinker and cement；the flows of energy resources and emissions related to fuel combustion are not evaluated in this study. Fuel tonnages and carbon dioxide emissions related to fuel combustion are discussed by van Oss andPado vani. Integrated assessment of energy and material flows are more data intensive and methodologically challenging and therefore the scope of this study is limited to material flows only.Estimates for cement cycle flow parametersFor this study, mine overbur den and (unused) stone fines were estimated as 6% and 1%, respectively, of crushed rock production from limestone quarries, following the findings of Matthews et al. Output of CKD was estimated at 0.2 metric ton per metric ton of clinker, based on the discussion by van Oss and Padovani；as noted by these authors, CKD data are subject to high uncertainties. Carbon dioxide emissions from calcination were estimated to be 0.51 metric ton of carbon dioxide per metric ton of clinker and are based on straightforward stoichiometric considerations. The data on production, imports, exports, and changes in stockpiles of clinker and cement are from USGS assessment of the cement industry and official trade data；The cement produced in the United States, as well as the net imports of cement, enter the use reservoir, and the cement flow within the use reservoir is divided into subflows：additions to stock (i.e., new construction)；repair/renovation；and retirement. Direct data on the breakout of cement sales (consumption) into new construction and repair/renovation are not available from USGS data on cement consumption；however, the PCA has developed indices that relate the tonnage of cement to the dollars spent, but mostly in terms of types of construction. The PCA’s tonnage rat io for new versus renovation residential construction (for the 5-year average of the period 2000–2004) is 75%–25%. Alternatively, this breakout between new and renovation construction can also be estimated by using the real dollar value of construction data and estimates of the cement intensity (tons per million dollars of spending) of different types of construction (Sullivan 2006, personal communication). The Construction Expenditures Branch of the U.S. Census Bureau (USCB) reports the annual total value of construction. However, only the data for private residential construction (current US$2200 billion total over the period 2000–2004) has any breakout for repair or renovation, i.e., new housing units (new single family current US$1400 billion；new multi family – current US$200 billion) and improvements (currentUS$600 billion). As part of its annual highway finance statistics, the FederalHighway Administration (FHWA) reported Federal and State funding for highways and bridges as totaling current US$279 billion for the period 2000–2004, split out as about 60% for new construction (current US$162 billion over 2000–2004) and about 40% for repair and rehabilitation (current US$117 billion over 2000–2004). Based on the weighted average of the USCB and FHWA data over the period 2000–2004, 70% of the total consumption tonnage of cement in the United States is estimated to have been used for new construction and the remaining 30% for repair and renovation activities. Although adoption of PCA or USCB/FHWA breakout ratios of cement consumption for new and renovation construction are significantly different, the likely error in using any one of the approximations would be in the range 5%–10%. Therefore, for this study, we assume that the breakout ratio between new and renovation construction is 65 ：35. It also can be anticipated the repair and rehabilitation of deteriorating highways currently in use would push the renovation component o cement consumption to a higher value. It is important to note that new construction projects are expected to consume more concrete overall than repair and renovation work, andthat unit prices for concrete will generally be lower for large.New construction, repair/renovation activities, and demolition of old infrastructure all generate C&D debris. Estimates of C&D debris from residential and nonresidential buildings were derived from a U.S. Environmental Protection Agency (USEPA) reportand modeling by Kapur et al.；the latter study also models roads, bridges, highways, and other civil infrastructure. The in-use cement stock was estimated as the difference between cement entering the use reservoir and cement discards in the form of C&D debris exiting the use reservoir. The net trade flows of cement within finished products (e.g., concrete tiles) were excluded owing to the lack of data on the cement content of these products.In the end-of-life reservoir, concrete can be either recycled to the use reservoir or disposed of to the environment (landfills). There also could be net import–export flows (likely minor) of C&D debris containing cement discards. Data on recycling of C&D debris are limited. The USGS reports that 9.5 million metric tons of concrete were recycled in the United States in 2000, but these data are likely to be incomplete. For ons ite C&D debris, the Associated General Contractors of America (AGC) conducted in 2004 a survey on the recycling practices of about 300 contractors. This survey showed that, depending onthe type of the project (building, highway, utility, or demolition), t he recycling rate for the concrete fraction of the C&D debris generated varied from 33% to 100% 。
班组比较管理英文Team comparative management refers to the practice of managing different teams within an organization and comparing their performance, efficiency, and effectiveness. It involves evaluating the performance of different teams, identifying best practices, and implementing strategies to enhance overall team performance and achieve organizational goals. In this article, we will discuss the importance of team comparative management and some strategies to effectively manage and compare teams within an organization.Importance of Team Comparative Management:1. Performance Evaluation: Team comparative management allows organizations to evaluate the performance of different teams and identify areas of improvement. By comparing teams, organizations can understand the strengths and weaknesses of each team and take necessary actions to enhance performance.2. Knowledge Sharing: Comparative management facilitates knowledge sharing among teams. It allows teams to learn from each other's experiences, best practices, and success stories. This helps in promoting a culture of collaboration and continuous learning within the organization.3. Goal Alignment: Comparative management ensures that all teams are aligned with the organization's goals and objectives. By comparingteams, organizations can identify if any team is lagging behind in achieving the set targets and take corrective actions to align them with the organizational goals.4. Resource Allocation: Comparative management helps in effective resource allocation. By comparing the performance and resource requirements of different teams, organizations can allocate resources more efficiently and effectively. This prevents wastage of resources and ensures their optimal utilization.Strategies for Effective Team Comparative Management:1. Clearly Define Evaluation Criteria: It is essential to establish clear and objective evaluation criteria to compare teams. These criteria can include factors like productivity, efficiency, quality, customer satisfaction, and team dynamics. Ensure that the evaluation criteria are aligned with the organization's goals and objectives.2. Regular Performance Reviews: Conduct regular performance reviews for each team to evaluate their progress and performance. Use a combination of quantitative and qualitative performance metrics to assess team performance. Provide constructive feedback and suggestions to help teams improve their performance.3. Identify Best Practices: Compare the practices and strategies adopted by different teams and identify the ones that produce the best results. Encourage teams to share their best practices and success storieswith other teams. Implement these best practices across different teams to enhance overall performance.4. Encourage Collaboration: Foster a culture of collaboration among different teams. Encourage teams to interact, share knowledge, and collaborate on projects. This promotes cross-functional teamwork and allows teams to learn from each other's experiences.5. Provide Training and Development: Identify skill gaps and training needs of different teams. Provide relevant training and development programs to enhance team members' skills and knowledge. This will help teams perform better and contribute more effectively towards the organization's goals.6. Recognize and Reward: Recognize and reward teams for their achievements and contributions. Implement a system of rewards and incentives to motivate teams and encourage healthy competition. This will create a positive and competitive environment, leading to improved team performance.In conclusion, team comparative management is crucial for organizations to evaluate team performance, identify best practices, and enhance overall performance. By implementing effective strategies and evaluation criteria, organizations can compare and manage their teams more efficiently. This will lead to improved productivity, collaboration, and goal alignment within the organization.。
骨代谢生化指标对骨质疏松的诊断价值陕西省结核病防治院（710100）王智存施婕邹远妩王卓中国正迈入老龄化社会，均统计，老年人群已占据全国人口约8.3%，且仍有不断上涨的趋势。
随着年龄增长，骨质疏松症的发病率呈直线上升趋势。
骨质疏松症是以骨量减少、骨的微观结构退变为特征，导致骨的脆性增加而容易发生骨折的一种全身性代谢性骨骼疾病。
骨密度（BMD）的测定是目前诊断骨质疏松症的主要方法。
双能X线骨密度测定仪（DEXA）具有精确度好、准确度高、测量范围广、速度快、辐射量少等优点，在临床上广为应用，已成为骨质疏松症诊断的有效手段和金标准[1，2]。
骨代谢生化指标是用于评估骨转换率有效的方法，具有简便、快速、无创伤性的特点。
本研究以电化学发光免疫分析法测定血清Ⅰ型前胶原氨基端前肽（PINP）、β-胶原降解产物（β-CTX）及N端骨钙素（N-MID）以及DEXA测定BMD，分析BMD与骨代谢生化指标之间的关系，探讨骨代谢生化指标对骨质疏松症的诊断价值。
1资料与方法1.1临床资料：215例骨质疏松老年患者均于2013年3月至2015年3月来我院就诊，排除影响骨代谢的急慢性疾病及药物后，诊断标准参照世界卫生组织（WHO）骨质疏松症诊断标准[3]。
采用美国GE公司生产的Lunar prodigy DEXA检测各部位BMD。
215例经BMD诊断为骨质疏松症患者中，以年龄对其分组，<70岁组106例，年龄55～70岁，平均（64±10）岁；≥70岁组109例，年龄70～91岁，平均（79±12）岁。
对照组110名，均为来我院进行健康体检的健康研究对象，均经BMD诊断为非骨质疏松症，年龄56～73岁，平均（63±7）岁。
1.2骨代谢指标的检测：采集所有研究对象的空腹静脉血，测量仪器为德国罗氏cobase601全自动电化学发光免疫分析仪，检测指标为PINP、β-CTX及N-MID。
1.3统计学处理：数据分析均采用SPSS13.0统计学软件包，计量资料用x±s表示，多组间比较采用方差分析，组间两两比较采用t检验，以P<0.05为差异有统计学意义。
牛分枝杆菌esat6和cfp10蛋白的表达及在临床检测中的应用解晓莉;韩猛;刘来兴;王基隆;杨美;张云飞;丁家波;张亮;杨宏军【摘要】本研究以牛分枝杆菌H37Rv基因组DNA为模板,扩增esat6和cfp10基因,构建重组表达载体pET-32a(+)-esat6和pET-32a(+)-cfp10,并通过原核表达系统分别表达重组esat6和cfp10蛋白,经Ni-NTA亲和层析法纯化后,对目的蛋白进行SDS-PAGE和Western blot验证,BCA法测定目的蛋白浓度,最后将east6和cfp10蛋白混合后用于牛结核病临床检测,并对检测数据进行分析.结果表明,牛分枝杆菌esat6和cfp10蛋白在大肠杆菌系统中获得高效表达;其混合蛋白应用于结核病检测具有较高的特异性,且在皮肤变态反应和IFN-γ释放试验两种检测方法中具有较高的符合率.说明相较于提纯结核菌素(PPD),esat6和cfp10混合蛋白具有较高的特异性和稳定性,将有希望替代PPD用于牛结核病检测.%In this study,the esat6 and cfp10 gene were cloned with genomic DNA of Mycobacterium bovis strain H37Rv as template.Recombinant expression vectors pET-32a (+)-esat6 and pET-32a (+)-cfp10 were constructed to express esat6 and cfp10 protein through the prokaryotic expression system.The recombinant proteins were purified by Ni-NTA affinity chromatography and verified with SDS-PAGE and Western blot.Furthermore,the protein concentrations were determined with BCA method.Then the two proteins were mixed to detect the BTB (bovine tuberculosis) and the results were analyzed.The results showed that esat6 and cfp10 protein were highly expressed inE.coli.There were high specificity and coincidence rate in skin allergic reaction and IFN-γrelease test using mixed protein as stimulator.This studyconfirmed that compared with PPD,esat6 and cfp10 mixed protein had higher specificity and stability and was a promising alternative in BTB detection.【期刊名称】《山东农业科学》【年(卷),期】2017(049)011【总页数】4页(P120-123)【关键词】牛分枝杆菌;esat6和cfp10蛋白;皮肤变态反应;IFN-γ释放试验【作者】解晓莉;韩猛;刘来兴;王基隆;杨美;张云飞;丁家波;张亮;杨宏军【作者单位】山东省农业科学院奶牛研究中心,山东济南 250000;山东省农业科学院奶牛研究中心,山东济南 250000;山东省农业科学院奶牛研究中心,山东济南250000;山东省农业科学院奶牛研究中心,山东济南 250000;山东省农业科学院奶牛研究中心,山东济南 250000;山东省农业科学院奶牛研究中心,山东济南 250000;中国兽医药品监察所,北京 100081;山东省农业科学院奶牛研究中心,山东济南250000;山东省农业科学院奶牛研究中心,山东济南 250000【正文语种】中文【中图分类】S858.23牛结核病(bovine tuberculosis)是由牛型分枝杆菌引起的一种人畜共患慢性消耗性传染病，在世界各国均有发生[1]。
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Comparative evaluation of 11essential oils of different origin as functional antioxidants,antiradicals and antimicrobials in foodsGianni Sacchetti a ,Silvia Maietti a ,Mariavittoria Muzzoli a ,Martina Scaglianti b ,Stefano Manfredini b ,Matteo Radice c ,Renato Bruni d,*aDipartimento delle Risorse Naturali e Culturali,Lab.Biologia farmaceutica &Biotrasformazioni,Universita`degli Studi di Ferrara,C.so Porta Mare 2,I-44100Ferrara,ItalybDipartimento di Scienze Farmaceutiche,Universita`degli Studi di Ferrara,via Fossato di Mortara 17–19,I-44100Ferrara,Italy cFundacion Chankuap Õ,Macas,EcuadordDipartimento di Biologia Evolutiva e Funzionale,Sez.Biologia Vegetale e Orto Botanico,Universita`degli Studi di Parma,Parco Area delle Scienze 11A,43100Parma,ItalyReceived 15March 2004;received in revised form 22June 2004;accepted 22June 2004AbstractEleven essential oils,namely,Cananga odorata (Annonaceae),Cupressus sempervirens (Cupressaceae),Curcuma longa (Zingiber-aceae),Cymbopogon citratus (Poaceae),Eucalyptus globulus (Myrtaceae),Pinus radiata (Pinaceae),Piper crassinervium (Piperaceae),Psidium guayava (Myrtaceae),Rosmarinus officinalis (Lamiaceae),Thymus x citriodorus (Lamiaceae)and Zingiber officinale (Zingib-eraceae),were characterized by means of GC and GC–MS and evaluated for their food functional ingredient related properties.These properties were compared to those of Thymus vulgaris essential oil,used as a reference ingredient.Antioxidant and radi-cal-scavenging properties were tested by means of 1,1-diphenyl-2-picrylhydrazyl (DPPH)assay,b -carotene bleaching test and lumi-nol-photochemiluminescence (PCL)assay.In the DPPH assay,C.odorata ,C.citratus ,R.officinalis and C.longa showed major effectiveness,with a radical inhibition ranging from 59.6±0.42–64.3±0.45%.In the b -carotene bleaching test, C.odorata (75.5±0.53%),R.officinalis (81.1±0.57%)and C.longa (72.4±0.51%)gave the best inhibition results.Similar results were obtained for the same essential oils in the PCL assay.Antimicrobial properties were obtained on five food-spoilage yeasts:Candida albicans ATCC 48274,Rhodotorula glutinis ATCC 16740,Schizosaccharomyces pomb e ATCC 60232,Saccharomyces cerevisiae ATCC 2365,Yarrowia lypolitica ATCC 16617.C.citratus and T.x citriodorus were the most effective against the tested strains.Suggestions on relationships between chemical composition and biological activities are outlined.Ó2004Elsevier Ltd.All rights reserved.Keywords:Cananga odorata ;Cupressus sempervirens ;Curcuma longa ;Cymbopogon citratus ;Eucalyptus globulus ;Pinus radiata ;Piper crassinervium ;Psidium guayava ;Rosmarinus officinalis ;Thymus x citriodorus ;Zingiber officinale ;Thymus vulgaris ;Antioxidant activity;Photochemiluminescence;Antimicrobial activity1.IntroductionThe use of essential oils as functional ingredients in foods,drinks,toiletries and cosmetics is gaining momen-tum ,both for the growing interest of consumers in ingre-dients from natural sources and also because of increasing concern about potentially harmful synthetic additives (Reische,Lillard,&Eitenmiller,1998).Within the wide range of the above-mentioned products,a com-mon need is availability of natural extracts with a pleas-ant taste or smell combined with a preservative action,aimed to avoid lipid deterioration,oxidation and spoil-age by microorganisms.Those undesired phenomena0308-8146/$-see front matter Ó2004Elsevier Ltd.All rights reserved.doi:10.1016/j.foodchem.2004.06.031*Corresponding author.Fax:+00390521905403.E-mail address:bruni@biol.unipr.it (R.Bruni)./locate/foodchemFood Chemistry 91(2005)621–632Food Chemistryare not an exclusive concern of the food industry,but a common risk wherever a lipid or perishable organic sub-strate is present.In fact,they induce the development of undesirable off-flavours,create toxicity and severely af-fect the shelf-life of many goods(Farag,Ali,&Taha, 1990;Hirasa&Takemasa,1998).Until recently,essential oils have been studied most from the viewpoint of theirflavour and fragrance chem-istry only forflavouring foods,drinks and other goods. Actually,however,essential oils and their components are gaining increasing interest because of their relatively safe status,their wide acceptance by consumers,and their exploitation for potential multi-purpose functional use(Ormancey,Sisalli,&Coutiere,2001;Sawamura, 2000).Many authors,in fact,have reported antimicro-bial,antifungal,antioxidant and radical-scavenging properties(Hirasa&Takemasa,1998)by spices and essential oils and,in some cases,a direct food-related application has been tested(Madsen&Bertelsen,1995).The literature outlines different approaches within this trend and both the biological screening of new essential oils and the evaluation of new properties of al-ready marketed oils have been done.In both cases,dif-ferent methodological approaches lead to scattered results,which are hardly comparable and often conflict-ing(Koleva,van Beek,Linssen,de Groot,&Evstatieva, 2002;Mantle et al.,1998;Ruberto&Baratta,2000;Zy-gadlo,Lamarque,Maestri,&Grosso,1995).A plethora of different antioxidant assays is available and,because results rely on different mechanisms,they strictly depend on the oxidant/antioxidant models employed and on lipophilic/hydrophilic balance(Frankel,Huang,Kan-ner,&German,1994).A single-substance/single-assay produces relative results and it is perceived as a reduc-tive approach whenever a phytocomplex is involved. Therefore,a multiple-test and a simultaneous chemical characterization must be taken into account whenever assays of essential oils are performed to allow a balance between the sensory acceptability and functional properties.In the present paper,we report the results of a study aimed to define and compare functional antioxidant, antiradical and antimicrobial properties of11essential oils with some peculiarities related to chemical composi-tion.Study oils were:Cananga odorata(Annonaceae), Ylang–Ylang oil,Cupressus sempervirens(Cupressa-ceae),cupressus oil,Curcuma longa(Zingiberaceae), turmeric oil,Cymbopogon citratus(Poaceae),lemongrass oil,Eucalyptus globulus(Myrtaceae),eucalyptus oil, Pinus radiata(Pinaceae),Monterey pine oil,Piper crass-inervium(Piperaceae),guavidoca leaves oil,Psidium guayava(Myrtaceae),guayaba leaves oil,Rosmarinus officinalis(Lamiaceae),rosemary oil,Thymus x citriodo-rus(Lamiaceae),lemon thyme oil,and Zingiber officinale (Zingiberaceae),ginger oil.Thymus vulgaris essential oil was used as a reference ingredient.2.Materials and methods2.1.Essential oilsSamples were obtained via steam distillation as pure essential oils from a number of commercial sources and specimen samples have been kept for future refer-ence at the University of Ferrara,Dip.delle Risorse Naturali e Culturali.Cananga odorata essential oil was purchased from CTM,Verona,Italy;Cupressus semper-virens,Curcuma longa,Cymbopogon citratus,Eucalyptus globulus,Pinus radiata,Piper crassinervium,Psidium guayava and Zingiber officinale essential oils were pur-chased from Fundacion Chankuap,Macas,Ecuador, and came from locally cultivated plants.Rosmarinus officinalis and Thymus x citriodorus were purchased from Sorgeva,Ferrara,Italy,and came from plants cul-tivated in Sardinia,Italy,Thymus vulgaris essential oil, thymol chemotype,employed as reference,was purchased from Extrasynthese(Genay,France).The essential oil samples were stored in glass vials with tef-lon-sealed caps atÀ18±0.5°C in the absence of light.2.2.Gas chromatographyEssential oil samples were analyzed and the relative peak areas for individual constituents averaged.Quanti-fication was computed as the percentage contribution of each compound to the total amount present.The relative percentages were determined using a Fisons (Rodano,Milano,Italy)9130–9000series gas-chroma-tograph equipped with a Fisons EL980processor,a FID detector and a MEGA SE52(Mega,Legnano, Italy)5%poly diphenyl95%dimethylsiloxane bonded phase column(i.d.=0.32mm,length30m,film thick-ness=0.15mm).Operating conditions were as follows: injector temperature,280°C;FID temperature,280°C;carrier gas(Helium),flow rate2ml/min and split injection with split ratio1:40.Oven temperature was ini-tially45°C and then raised to100°C at a rate of1°C/ min,then raised to250°C at a rate of5°C/min andfi-nally held at that temperature for10min.1l l of each sample,dissolved in CH2Cl2(1:100v/v),was injected. The percentage composition of the oils was computed by the normalization method from the GC peak areas, calculated by means of three injections from each oil, without using correction factors.2.3.Gas chromatography/mass spectrometry analysisEssential oil constituents were analyzed by a Hewlett Packard HP5890series II plus gas chromatograph equipped with a HPMS5989b mass spectrometer using electron impact.The gas-chromatographic(GC)condi-tions were the same as reported for GC analysis and the same column was used.The mass spectrometry622G.Sacchetti et al./Food Chemistry91(2005)621–632(MS)conditions were as follows:ionization voltage,70 eV;emission current,40mA;scan rate,1scan/s;mass range,35–300Da;ion source temperature,200°C. The MS fragmentation pattern was checked with those of other essential oils of known composition,with pure compounds and by matching the MS fragmentation pat-terns with NIST NBS75K mass spectra libraries and with those in the literature(Adams,2001).The relative amounts of the individual components were obtained from GC analysis,based on peak areas without FID fac-tor correction.The constituents of the volatile oils were also identified by comparing their GC retention indices.A mixture of aliphatic hydrocarbons(C8–C24)in hexane (Sigma–Aldrich,St.Louis,USA)was injected as under the above-mentioned temperature programme to calcu-late the retention indices using the generalized equation of Van den Dool and Kratz(1963).2.4.Biological activities2.4.1.GeneralAll the biological activities of the tested essential oils were compared to those achieved from a commercial essential oil of Thymus vulgaris in order to have a ref-erence with a product reputed for its antioxidant (Dang,Takacsova,Nguyen,&Kristianova,2000), and antimicrobial properties(Dorman&Deans,2000; Zambonelli,Zechini DÕAulerio,Bianchi,&Albasini, 1996).Antioxidant activity was assessed by1,1-diphe-nyl-2-picrylhydrazyl(DPPH),b-carotene bleaching tests and luminol-photochemiluminescence(PCL)as-say,while antimicrobial activities were determined on five American Type Culture Collections(ATCC)yeast strains.The culture media and conditions employed were in accordance with ATCC protocols().All the data collected for each assay are the averages of three determinations of three independent experiments.2.4.2.Free radical-scavenging activity:DPPH testFree radical-scavenging activity of essential oils was measured according to the procedure of Choi,Song, Ukeda,and Sawamura(2000).An aliquot of essential oil(10l l)was mixed with900l l of100mM Tris–HCl buffer(pH7.4),40l l of ethanol and50l l of0.5% (w/w)Tween20(Sigma–Aldrich)solution and then added to1l l of0.5mM DPPH(Sigma–Aldrich)in eth-anol.Tween20was used as an oil-in-water emulsifier. The mixture was shaken vigorously and then immedi-ately placed in a UV–Vis spectrophotometer(Thermo-Spectronic Helios c,Cambridge,UK)to monitor the decrease in absorbance at517nm.Monitoring was con-tinued for70min until the reaction reached a plateau. The control sample was prepared using water instead of essential oils(blank sample).Trolox(1mM)(Sig-ma–Aldrich),a stable antioxidant,was used as a synthetic reference.The radical-scavenging activities of samples,expressed as percentage inhibition of DPPHÆ, were calculated according to the formula:Inhibition percentage(Ip)=[(A BÀA A)/A B]·100(Yen&Duh, 1994)where A B and A A are the absorbance values–checked after70min–of the the blank sample and of essential oil solutions,respectively.2.4.3.Antioxidant activity:b-carotene bleaching testAntioxidant activity of essential oils was determined using b-carotene bleaching test(Taga,Miller,&Pratt, 1984).Approximately10mg of b-carotene(type I syn-thetic,Sigma–Aldrich)was dissolved in10ml of chloro-form.The carotene-chloroform solution,0.2ml,was pipetted into a boilingflask containing20mg linoleic acid(Sigma–Aldrich)and200mg Tween40(Sigma–Aldrich).Chloroform was removed using a rotary evap-orator(Bu¨chi461Switzerland)at40°C for5min and, to the residue,50ml of distilled water were added, slowly with vigorous agitation,to form an emulsion. Five ml of the emulsion were added to a tube containing 0.2ml of essential oils solution prepared according to Choi et al.(2000)and the absorbance was immediately measured at470nm against a blank,consisting of an emulsion without b-carotene.The tubes were placed in a water bath at50°C and the oxidation of the emulsion was monitored spectrophotometrically by measuring absorbance at470nm over a60min period.Control samples contained10l l of water instead of essential oils.Butylated hydroxy anisole(BHA;Sigma–Aldrich), a stable antioxidant,was used as a synthetic reference. The antioxidant activity was expressed as inhibition percentage with reference to the control after a60min incubation using the following equation:AA= 100(DR CÀDR S)/DR C,where AA=antioxidant activ-ity;DR C=degradation rate of the control=[ln(a/b)/ 60];DR S=degradation rate in presence of the sam-ple=[ln(a/b)/60];a=absorbance at time0;b=absorb-ance at60min.2.4.4.PhotochemiluminescenceThe luminol-photochemiluminescence assay was car-ried out with the procedure described by Popov and Le-win(1999)and adapting the standard protocol.The essential oils were measured in the PhotochemÒwith the ACL kit(AnalytikJena,Jena,Germany).A2.30 ml portion of reagent1(solvent and dilution reagent), 200l of reagent2(buffer solution),25l l of reagent3 (photosensitizer),and10l l of standard(trolox solution in reagent1)or sample(essential oil in methanol)solu-tion were mixed and measured.A light emission curve was recorded over130s,using inhibition as the param-eter to evaluate antioxidant potential.The antioxidant capacity was then determined by using the integral un-der the curve and was expressed as mmol/l of trolox used as standard to obtain a calibration curve.DetailedG.Sacchetti et al./Food Chemistry91(2005)621–632623description of the method is given elsewhere(Popov& Lewin,1999).2.4.5.Antimicrobial activityThe biological activity against yeasts was determined by employing the standard discs diffusion technique (Benson,1990;Okeke,Iroegbu,Eze,Okoli,&Esimone, 2001).Antifungal activity was assessed on the yeasts Candida albicans ATCC48274,Rhodotorula glutinis ATCC16740,Schizosaccharomyces pombe ATCC 60232,Saccharomyces cerevisiae ATCC2365,and Yarr-owia lypolitica ATCC16617.Mother cultures of each micro-organism were set up24h before the assays in or-der to reach the stationary phase of growth.The tests were assessed by inoculating Petri dishes from the mother cultures with proper sterile media,with the aim of obtaining the micro-organism concentration of 105colony forming units(CFU)/ml.An aliquot of dimethylsulfoxide(DMSO;Sigma–Aldrich)was added to the essential oils in order to obtain a0.01–0.75mg/ ml concentration range.Serial dilutions of the DMSO/ essential oil solution were deposited on sterile paper discs(6mm diameter,Difco)which were subsequently placed in the centre of the inoculated Petri dishes.There-fore,the Petri dishes were then incubated at37°C for 24h and the growth inhibition zone diameter(IZD) was measured to the nearest mm.The lowest concentra-tion of each DMSO/essential oil solution deposited on the sterile paper disc showing a clear zone of inhibition was taken as the minimum inhibitory concentration (MIC)(Okeke et al.,2001).Controls were set up with DMSO in amounts corresponding to the highest quan-tity present in the test solution.2.5.Statistical analysisRelative standard deviation was obtained as appro-priate.Analyses of variance(Anova),followed by LSD post hoc determinations,were performed.All computa-tions were done using the statistical software STATIS-TICA6.0(StatSoft Italia srl).3.Results and discussion3.1.Chemical compositionDifferent kinds of essential oils were tested,from those with a typical monoterpene hydrocarbon pattern (Psidium guayava,Pinus radiata,Cupressus sempervi-rens,Piper crassinervium,Eucalyptus globulus)to those characterized by the presence of aldehydes(Cymbopo-gon citratus),benzyl esters(Cananga odorata),phenyl-propanoids(Curcuma longa,Zingiber officinale), phenolics(Thymus vulgaris),alcohols(Thymus x citriod-orus)and ketones(Rosmarinus officinalis).Their percent composition is shown in Table1.The most abundant components in P.crassinervium essential oil,which has not been investigated before,were limonene(26.6%), a-and b-pinene(10.0%and15.2%,respectively);smaller amounts of piperitone,safrole and a-terpinyl acetate and,notably,carvotacetone acetate(8.15%)content were also detected.Some of the essential oils–C.citra-tus,C.sempervirens,E.globulus,C.odorata showed only minor differences in composition with respect to data re-ported in the literature(Gaydou,Randriamiharisoa, Bianchini,&Llinas,1988;Menut et al.,2000;Milos, Radonic,&Mastelic,2002;Weiss,1997).On the other-hand,Psidium guayava leaves essential oil,obtained from plants grown in Amazonian Ecuador,was found to be rich in limonene(33.3%),in accordance with pre-vious reports(Ogunwande,Olawore,Adeleke,Ekun-dayo,&Koenig,2003),but also rich in a-pinene (29.5%)instead of b-caryophyllene and with sesquiterp-enic content as elsewhere reported(Pino,Aguero,Mar-bot,&Fuentes,2001).The scarcely investigated P. radiata essential oil,extracted from plants grown in Sal-inas de Guaranda in Andean Ecuador,was consituted of a-and b-pinene(20.9%and35.2%),b-phellandrene (12.6%)and almost lacking in sesquiterpenes(1.18%). These data are in agreement with those obtained by Petrakis et al.(2001)for Greek plants.Both C.longa and Z.officinale oils are derived from plants cultivated in Amazonian Ecuador.Thefirst showed a notable amount of a-and b-turmerone(19.8and7.35%)and was found to be rich in monoterpenes,such as a-phel-landrene(20.4%),1,8cineole(10.3%)and terpinolene (6.19%).On the otherhand,in the case of Z.officinale oil,only minor amounts of hydrocarbons were detected. Major components were zingiberene(23.9%),b-bisabo-lene(11.4%)and b-sesquiphellandrene(10.9%).The principal components detected in European hybrid T. x citriodorus were geraniol(36.4%)and geranil acetate (22.4%).It is interesting to note that such a pattern of abundance of the latter was not reported previously (Stahl-Biskup&Holthuijzen,1995;Zani et al.,1991). Rosmarinus officinalis,Sardinian ecotype,was rich in verbenone(21.8%)and borneol(10.4%)and its compo-sition was rather different from that of rosemary oils produced in other Mediterranean countries(Baratta, Dorman,Deans,Biondi,&Ruberto,1998;Svoboda& Deans,1992;Tuberoso,Satta,Cabras,&Garau,1998).3.2.Antioxidant activityIn light of the differences among the wide number of test systems available,the results of a single-assay can give only a reductive suggestion of the antioxidant prop-erties of essential oils toward food matrices and must be interpreted with some caution.Moreover,the chemical complexity of essential oils,often a mixture of dozens of compounds with different functional groups,polarity624G.Sacchetti et al./Food Chemistry91(2005)621–632and chemical behaviour,could lead to scattered results, depending on the test employed.Therefore,an approach with multiple assays in screening work is highly advisa-ble.Among the plethora of methods that can be used for the evaluation of the antioxidant activity(TEAC, TRAP,LDL,DMPD,FRAP,ORAC,DPPH,PCL, and b-carotene bleaching),very few of them(TEAC, DPPH,PCL)are useful for determining the activity of both hydrophilic and lipophilic species,thus ensuring a better comparison of the results and covering a wider range of possible applications.Taking this into account, the in vitro antioxidant activity of the11essential oils tested,compared to that of Thymus vulgaris essential oil,was assessed by three different tests:the DPPH test, the b-carotene bleaching test and the PCL assay,which allow both the primary and the secondary step of oxida-tion(Mantle et al.,1998)and the lipid soluble antioxi-dant capacity to be followed.The DPPH radical-scavenging activities of the11 essential oils and of references are shown in Fig.1.C. odorata,C.citratus,R.officinalis and C.longa essential oils notably reduced the concentration of DPPH free radical,with an efficacy slightly lower than that of refer-ence oil T.vulgaris(75.6±0.53%inhibition).Their val-ues,in fact,ranged from63.8±0.45%to59.6±0.42% and were twice higher than that of trolox (28.2±0.20%).The performance of the peculiar rose-mary oil chemotype was better than those reported by Baratta et al.(1998)for samples obtained from R.offici-nalis of the a-pinene/1,8cineole/camphor chemotype.It must be pointed out that C.citratus essential oil,ex-tracted from Ecuadorian-grown plants performed better than essential oils of the same botanical source but of diffent geographical origin(Menut et al.,2000).How-ever,given the fact that citral isomers(neral,32.3%;ger-anial,41.28%)are the most abundant compounds in C. citratus essential oil,the results achieved seem to be compliant with citral radical-scavenging efficacy re-ported by Choi et al.(2000).P.crassinervium oil activity (43.0±0.30%)was clearly lower than that expressed by T.vulgaris,but comparable to that of trolox.Other essential oils performed poorly,with an average inhibi-tion percentage lower than25%.Oils with a higher monoterpenic abundance,such as C.sempervirens,P.ni-gra,E.globulus and P.guayava,were almost ineffective. This result is in agreement with the poor performance given by other oils with similar patterns and by single monoterpenic hydrocarbons(Ruberto&Baratta,2000).We assessed the lipid peroxidation inhibitory activity of the essential oils by the b-carotene bleaching test (Fig.2).Results were consistent with data obtained from the DPPH test,as C.odorata(75.5±0.53%inhibition), R.officinalis(81.1±0.57%)and C.longa(72.4±0.51%) performed almost as well as T.vulgaris(90.9±0.64%) and BHA(86.74±0.61%).P.crassinervium,along with E.globulus,C.citratus and C.sempervirens,provided intermediate results,with inhibition percentages ranging from65.9±0.46to48.6±0.34%.Overall results were better than those provided by the radical-scavenging activity and some of the oils with highterpenicG.Sacchetti et al./Food Chemistry91(2005)621–632629percentages were more effective,probably as a conse-quence of a higher specificity of the assay for lypophilic compounds.The PCL method is based on the photo-induced aut-oxidation inhibition of luminol by antioxidants medi-ated from the radical anion superoxideðOÅÀ2Þ.Becausethis latter is a deleterious by-product of oxygen metabo-lism,responsible for the most important damage related to reperfusion injuries,the values obtained by the PCL method directly relate to health properties of a given ingredient or food.This method is easy and rapid to per-form,and presents numerous advantages:it does not re-quire high temperatures to generate radicals and it is more sensitive,measuring,in a few minutes,and in the nanomolar range,the scavenging activity of antioxi-dants against the superoxide radical.Moreover,the PCL assay,conducted under the ACL protocol,is par-ticularly suitable for determining the radical-scavenging activity of lipid-soluble antioxidants such as essential oils.Data obtained from PCL testing(Table2)were consistent with those obtained in the previous tests.Ref-erence oil,T.vulgaris,was the most potent(342±21.8 mmol trolox/l)while C.odorata,C.longa,C.citratus and R.officinalis confirmed the good results achieved in the DPPH and b-carotene bleaching assays.They provided values ranging from23.3±0.30to66±4.2 mmol trolox/l.As previously reported,P.crassinervium efficacy was still considerable(10.2±0.44mmol trolox/ l),while the other oils were almost ineffective.3.3.Antimicrobial activityResults from the antimicrobial disc-diffusion assay are summarized in Table3.Most of the essential oils showed a moderate inhibiting activity against the tested yeasts.In particular,the oils of C.citratus and T.x citriodorus showed very good effectiveness and the most broad-spectrum activity,with MIC comparable to,or even better than,those provided by the reference oil, T.vulgaris.Even though the antifungal activity of lem-ongrass oil has been reported several times,mostly against phytopathogens and dermatophytes,its activity against food-spoilage yeasts was scarcely investigated. Geraniol and citral isomers should probably account for such efficacy(Abe et al.,2003;Tawil&Yousef, 1988).On the otherhand,C.odorata,P.crassinervium and C.longa were the worst performers,with MIC5 or10times higher than those of T.vulgaris.P.radiata essential oil displayed specific narrow-spectrum activity only against S.cerevisiae with a0.02mg/ml MIC.Sim-ilar behaviour was observed for C.odorata oil against Yarrowia lypolitica(0.03mg/ml).S.pombe and S.cere-visiae were the most sensitive strains,as their MIC were the lowest in most cases.On the otherhand,Y.lypoli-tica showed strong resistance against many monoter-pene-rich oils,such as C.sempervirens,P.guayava,P. radiata,and E.globulus,and a higher sensitivity for those oils with good phenolic,alcoholic or aldehydicTable2Photochemiluminescence(PCL)of11essential oils and reference oil(Thymus vulgaris)expressed as mmol equivalents of trolox per litre ofsample±standard deviationEssential oils mmol trolox/lCananga odorata31.7±0.3Cupressus sempervirens0.79±0.04Curcuma longa28.1±1.45Cymbopogon citratus23.3±0.30Eucalyptus globulus0.50±0.033Pinus radiata0.85±0.005Piper crassinervium10.2±0.44Psidium guayava0.84±0.02Rosmarinus officinalis66.0±4.2Thymus·citriodorus 1.54±0.05Zingiber officinale0.94±0.02Thymus vulgaris342±21.8Table3Antimicrobial activity expressed as minimum inhibitory concentration(MIC a)against some yeast strains of11essential oils and reference oil (Thymus vulgaris)C.albicans R.glutinis S.cerevisiae S.pombe Y.lypolitica Essential oils mg/mlCananga odorata0.170.230.540.270.03 Cupressus sempervirens0.080.080.060.060.23 Curcuma longa0.360.180.180.060.15 Cymbopogon citratus0.030.030.020.020.03 Eucalyptus globulus0.090.090.090.120.24Pinus radiata0.140.090.020.060.29Piper crassinervium0.240.090.300.120.12 Psidium guayava0.140.090.090.060.23 Rosmarinus officinalis0.090.120.060.180.12 Thymus·citriodorus0.060.090.060.060.03 Zingiber officinale0.150.150.090.060.18 Thymus vulgaris0.060.060.060.030.03a MIC was considered as the lowest concentration of each essential oil showing a clear zone of inhibition.630G.Sacchetti et al./Food Chemistry91(2005)621–632contents.The different performances offered by essen-tial oils,in fact,can be linked to their different chemical compositions.As previously reported,yeasts and fungi are markedly inhibited by oils rich in phenolics,alde-hydes and alcohols(Bruni et al.,2003;and references therein).4.ConclusionNatural extracts are in increasing demand from the manufacturers of foods,cosmetics and pharmaceuticals. Thus the importance of conducing studies on essential oils,lies not only in the chemical characterization but also in the possibility of linking the chemical contents with particular functional properties.In this regard,it is advisable to use methods for the assessment of biolog-ical activities that not only highlight aromatic or pre-servative activities but also correlate with functional properties potentially useful for pharmaceuticals,nutri-ceuticals and cosmetic applications.Following this idea, we have used a convergent approach that has taken into account the use of complementary methods to assess radical-scavenging and antioxidant properties(b-caro-tene bleaching,DPPH,PCL),which are a very impor-tant for health claims in nutriceutical products.In particular,we make use of PCL that measures the abil-ity,of a given substance or mixture,to quench OÅÀ2,oneof the most dangerous reactive oxygen species(ROS)for human health.Moreover,all the tested oils were also investigated for their 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