检索结果-南通市图书馆

Fossil Stomatocysts in Upper Cretaceous Sedimentary Pyrite from Central Mexico

International Journal of Geosciences 2014年第2期5卷 214-221页

作者： Carlos Castaneda-Posadas Alberto Blanco-Pinon Juan Hernandez-Avila Silvia P.Ambrocio-Cruz Liliana Lizarraga-Mendiola Susana A.Angeles-Trigueros Laboratorio de Paleontologia-escuela de Biologia Benemerita Universidad Autonoma de PueblaPueblaMexico Area Academica de Ciencias de la Tierra y Materiales Universidad Autonoma del Estado de HidalgoHidalgoMexico Area Academica de ingenieria Universidad Autonoma del Estado de HidalgoHidalgoMexico Instituto de Geologia Universidad Autonoma de San Luis PotosiSan Luis PotosiMexico

In this paper six fossil forms of Chrysophycean stomatocysts are described. The material was collected from sedimentary pyrite embedded in well-laminated organic-rich limestone of the Upper Cretaceous Agua Nueva Formation at the locality of Xilitla, Central Mexico. The stomatocysts are represented by two spherical specimens with smooth surfaces lacking of ornamentation, three ovoid forms with rugose textures, one of them exposing presence of pore without collar, and one spherical specimen showing rugose texture and the presence of two short and rounded projections. The specimens here described showed affinity with some stomatocysts morphotypes described for brackish and fresh water, but not for known marine specimens. The presence of these microfossils in the Agua Nueva Formation represents the first formal description of fossil stomatocysts in Upper Cretaceous sedimentary pyrite in Mexico. The occurrence of both micro (planktonic foraminifera, calcispheres, radiolarians) and macrobiota (ammonites, inoceramid bivalves and fishes) and the presence of the specimens in sedimentary pyrite suggest that the stomatocysts were preserved under oxygen-deficiency conditions in a low energy environment. This event could have occurred in open marine waters in the Tampico-Misantla basin (Central Mexico) during the late Cenomanian throughout the early Turonian.

关键词： Fossil Stomatocysts Upper Cretaceous Agua Nueva Formation Mexico Sedimentary Pyrite

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Numerical Study of a Novel Procedure for Installing the Tower and Rotor Nacelle Assembly of Offshore Wind Turbines Based on the Inverted Pendulum Principle

引用

Journal of Marine Science and Application 2017年第3期16卷 243-260页

作者： Wilson Guachamin Acero Zhen Gao Torgeir Moan department of Marine Technology Norwegian University of Science and Technology Trondheim NO-7491 Norway departamento de ingenieria mecanica Escuela Politecnica Nacional Quito 17-01-2 759 Ecuador Centre for Ships and Ocean Structures Norwegian University of Science and Technology Trondheim NO-7491 Norway Centre for Autonomous Marine Operations and Systems Norwegian University of Science and Technology Trondheim NO-7491 Norway

Current installation costs of offshore wind turbines(OWTs) are high and profit margins in the offshore wind energy sector are low, it is thus necessary to develop installation methods that are more efficient and practical. This paper presents a numerical study(based on a global response analysis of marine operations) of a novel procedure for installing the tower and Rotor Nacelle Assemblies(RNAs) on bottom-fixed foundations of OWTs. The installation procedure is based on the inverted pendulum principle. A cargo barge is used to transport the OWT assembly in a horizontal position to the site, and a medium-size Heavy Lift Vessel(HLV) is then employed to lift and up-end the OWT assembly using a special upending frame. The main advantage of this novel procedure is that the need for a huge HLV(in terms of lifting height and capacity) is eliminated. This novel method requires that the cargo barge is in the leeward side of the HLV(which can be positioned with the best heading) during the entire installation. This is to benefit from shielding effects of the HLV on the motions of the cargo barge, so the foundations need to be installed with a specific heading based on wave direction statistics of the site and a typical installation season. Following a systematic approach based on numerical simulations of actual operations, potential critical installation activities, corresponding critical events, and limiting(response) parameters are identified. In addition, operational limits for some of the limiting parameters are established in terms of allowable limits of sea states. Following a preliminary assessment of these operational limits, the duration of the entire operation, the equipment used, and weather-and water depth-sensitivity, this novel procedure is demonstrated to be viable.

关键词： offshore wind turbine installation crane vessel shielding effects critical events limiting parameters inverted pendulum allowable sea states

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Nanotechnology in aquaculture: Applications, perspectives and regulatory challenges

引用

Aquaculture and Fisheries 2022年第2期7卷 185-200页

作者： Carlos Fajardo Gonzalo Martinez-Rodriguez Julian Blasco Juan Miguel Mancera Bolaji Thomas Marcos de Donato School of Tourism and Maritime Technology Polytechnic of Leiria(MARE-IPLeiria)Santuario de Nossa Senhora dos RemediosCampus 4Peniche2520-641Portugal department of Biology Faculty of Marine and Environmental SciencesInstituto Universitario de Investi-gaci´on Marina(INMAR)Campus de Excelencia Internacional del Mar(CEI⋅MAR)University of Cadiz(UCA)Puerto Real11519Spain Institute of Marine Sciences of Andalusia(ICMAN) Department of Marine Biology and AquacultureSpanish National Research Council(CSIC)Puerto Real11519Spain department of Biomedical Sciences Rochester Institute of TechnologyRochester14623USA Tecnologico de Monterrey Escuela de Ingenieria y CienciasQueretaro76130Mexico

Aquaculture is considered one of the most important food production systems both in terms of economic impact and food security,and the ongoing development of this industry is a key factor in the strategy to guarantee global nutritional ***,different types of nanotechnology-based systems have been employed to increase its production,efficiency and *** efforts have been made in the fields of health management,enhancement of fish and shellfish development by dietary supplementation with nutraceuticals,but also in the processing and preservation of seafood and water treatment,among ***,nanotechnology has a significant role to play in the improvement of the efficiency and the environmental impact of this *** this perspective,we propose to review the current situation of nanotechnology in the field of aquaculture and fisheries,emphasizing not only in current applications,and future prospects,but also in the ethical and governance aspects associated with this topic.

关键词： Health management Nano-regulation Nutraceuticals Preservation of seafood Risk assessment

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Sequential Injection Analysis of Ampicillin in Pharmaceuticals by Using Potentiometric detectors Based on PVC and Sol-Gel Membranes

引用

American Journal of Analytical Chemistry 2011年第4期2卷 491-499页

作者： Nestor Zarate Alberto N.Araujo M.Conceicao B.S.M.Montenegro Ricardo Perez-Olmos Dpto.Quimica Analítica Escuela Universitaria de Ingenieria Tecnica IndustrialUniversidad del Pais VascoPlaza de la Casilla 348012Bilbao REQUIMTE Dpto.de Quimica FisicaFaculdade de FarmaciaUniversidade do PortoRua Anibal Cunha 1644050 PortoPortugal

This work describes the construction and the evaluation of the general performance of new ampicilli-nate-selective electrodes based on manganese (III) tetraphenylporphyrin [Mn(III) TPP-Cl] as ionophore, incorporated in both PVC and sol-gel membranes and directly applied onto a conductive graphite/epoxy resin support. The units were constructed without inner reference solution adopting conventional configuration and in the case of PVC membrane the tubular configuration was also adopted. The good working characteristics of these electrodes, made possible its application to the determination of ampicillin in pharmaceuticals formulations, both in conventional batch analysis and in flow conditions, when the electrodes were coupled to a SIA system. In the last case the potentiometric sensors presented linear response towards ampicillin concentration between 5.0 × 10–4 and 5.0 × 10–2 mol?l–1 with slopes of –57.4 and –63.5 mV?dec–1 for the PVC and sol-gel membranes, respectively. The developed procedures enable mean relative standard deviations better than 3% for all the samples analysed. The obtained results do not statistically differ from those furnished by applying the HPLC reference method.

关键词： Ampicillin SIA Potentiometric detection Pharmaceutical Formulations

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Compliance Experimental determination in Nonstandard SEN Samples in API 5L Steel Pipe in the Short Radial Direction

引用

材料科学与工程：中英文版 2010年第5期4卷 27-32页

作者： Daniel Angeles Herrera Gonzailez Velaizquez Jorge Luis Morales Ramirez Angel de Jesus departamento de lngenieria y Materiales Instituto Polit~cnico Nacional Escuela Superior de Ingenieria Quimica e IndustriasExo-activas Mexico D.F 07738 Mexico

Compliance of nonstandard curved SEN samples was determined in the short radial direction of a 0.9144 m of diameter and 0.0254 of thickness in an API 5L steel pipeline. The experiment was carried out by means of an arc-bended sample with the same curvature radious of the pipe’s body. Compliance was determined by measuring the crack opening displacement (COD) at different crack lengths. The specimens were pre-cracked by a controlled fatigue in a servohydraulic machine by differential load, applying several load-unload cycles for different crack sizes. A compliance function could be obtained by means of the test: C = 0.138751 - 0.02783*(a ) + 0.001475*(a )2, on the basis of which an expression for the KI factor for the particular specimen’s geometry was obtained: K = PS/BW3/2*(13.914*a ’2 – 6.057*a ’ + 0.938). Furthermore, the mechanical behavior was completed by means of a study about the specimen deformation at different test points.

关键词：不锈钢管道实验测定 API 非标准径向教育样品裂纹长度

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Biosorption of Chlorothalonil on Fique＇s Bagasse （Furcraea sp.）： Equilibrium and Kinetic Studies

引用

材料科学与工程（中英文版） 2010年第6期4卷 1-8页

作者： Adriana Maria Quinchfa-Figueroa Margarita Enid Ramfrez-Carmona Geovanna Tafurt-Garcfa ingenieria Ambiental Escuela de lngenieria de Antioquia Medellin 7516 Colombia Centro de Estudio y de Investigacion en Biotecnologla Universidad Pontificia Bolivariana Medellin 56006 Colombia

The bagasse generated as residue during the process of fiber extraction of the fique or sisal (Furcraea sp.) has been evaluated in raw state, washed and thermally activated for the adsorption of chlorothalonil (CLT). The study was developed at 25 ℃ the effects of contact times, biomass dose and pH were investigated. The bagasse was characterized using Scanning electronic Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). A significant change in the signal spectroscopics was found in the thermally activated material. The experimental data obtained in this study shows that the fique’s bagasse is a material with potential to be used in adsorption of pollutants. The maximum uptake was 57.143 mg/g for the thermally activated material. This outcome constitutes a good contribution in environmental and technical terms.

关键词：甘蔗渣吸附百菌清动力学傅立叶变换红外光谱扫描电子显微镜平衡藻

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Tribological Properties and Corrosion Resistance Enhancement of H13 Hot Work Steel by Means of CrN/TiN Multilayers

引用

材料科学与工程（中英文版） 2010年第6期4卷 51-59页

作者： Bejarano Gaitan Gilberto Gomez Botero Maryory Osorio Alberto Jaime Caicedo Anguio Julio Aperador Chaparro William Grupo de Corrosion y Proteccion de la Universidad de Antioquia Calle 67 No 53-108 Medellin Colombia Grupo de Estado Solido de la Universidad de dntioquia Calle 67 No 53-108 Medellin Colombia Grupo de Peliculas delgadas Dpto de Fisica Universidad del Valle Calle 13 No 100-000 Cali Colombia lngenieria mecanica Escuela Colombiana de Ingenieria AK 45 No. 205-59 Bogota Colombia

Steel AISI H13 is used mainly for fabrication of hardened hot work tools; however life time of this steel is limited by its relatively low wear and corrosion resistance, if it would be exposed to an aggressive environment. It is widely known that the performance of tools and parts that undergo high mechanical load can be enhanced by the use of monolayer hard thin coatings. However, the use of such coatings as corrosion barriers is often unsatisfactory, since the deposition processes usually generate small pores and pinholes, which negatively affect the electrochemical behaviour of the coating/substrate system. On the other hand, if a hard thin film covers a less noble material, such as steel, small anodic areas could be generated and exposed to an aggressive environment a galvanic corrosion would take place. Therefore, it is also necessary to optimize the design of the coating system used in order to achieve the better relationship between mechanical and electrochemical properties for the whole system. The intention of the presented work was to enhance the tribological properties and corrosion resistance of steel AISI H13 through the use of a CrN/TiN multilayer coatings system, which were deposited by using the balanced magnetron sputtering technique.

关键词：热作模具钢摩擦学性能耐腐蚀性氮化钛 H13 性能增强多层膜 CrN

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Physico-Chemical Features and Catalytic Activity of ZrO2-MoO3

引用

材料科学与工程（中英文版） 2010年第9期4卷 1-9页

作者： Hernandez Juan Garcia Luz Cortez Luz Garcia Ricardo Handy Brent Cairdenas Maria Cueto Arturo Instituto Politecnico Nacional Escuela Superior de Ingenieria Textil Av. lnstituto Politecnico Nacional S/N Edificio # 8 Col. Linda Vista Mexico D.F. 07738. Mexico Instituto Tecnologico de Cd. Madero Division de Estudios de Posgrado e Investigacion Cd. Madero Tam. 89440 Mexico CIEP Facultad de Ciencias Qulmicas Universidad Aut6noma de San Luis Potosi San Luis Potosl 78210 Mdxico Universidad Autonoma Metropolitana-Azcapotzalco Av. San Pablo #180 Col. Reynosa Tamaulipas Delegacin Azcapotzalco Mexico D.F. 02200 oMexico

Zirconium hydroxide synthesized by sol-gel was impregnated with an aqueous solution of ammonium heptamolybdate in order to obtain 15 wt% of MoO3 on ZrO2. Pure and modified hydroxides were calcined at 400, 500, and 600 oC. In order to evaluate the catalytic activity for n-hexane isomerization, the materials were impregnated with 0.5 wt% of platinum and treated at 400 oC. For pure ZrO2 it was observed that the surface area decreases from 144 to 18 m2/g when the calcination temperature increases from 400 to 600 oC. The addition of Mo to zirconia increases the specific surface area (238-130 m2/g) in samples treated at the same temperatures. Pure zirconia transformed from tetragonal to monoclinic phase when calcined between 400 and 600 °C. However, this transformation did not occur in the ZrO2-MoO3 supports. The n-butylamine results showed that all the ZrO2-MoO3 supports presented a higher acidity (> 255 mV) than that corresponding to pure ZrO2 (- 48 mV), which presented only weakly acidic sites. Pt/ZrO2-MoO3 calcined at 600 oC proved to be the best catalyst for n-hexane isomerization, presenting a high selectivity to isomerization products (82%) at high conversion (72%).

关键词： MoO3 ZrO2 催化活性物理化学特征氢氧化锆焙烧温度比表面积浸渍材料

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：