bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Iron Oxide Nanotubes and Their Neuronal Applications
Authors: Xie Jining , Chen Linfeng , Varadan Vijay K. , Srivastan Malathi
Published: January 2011

Due to their unique structural and magnetic properties, magnetic nanotubes could be used in the field of neuroscience. In this study, hematite and maghemite nanotubes were synthesized and characterized. These magnetic nanotubes with coupled proteins such as albumin or laminin were used to investigate the interaction of nanotubes and their influence on somatosensory neurons from the dorsal root ganglion of rat. Our results indicated differential effects of magnetic nanotubes on neuronal growth based on the nanomaterial.
Alkanethiol Self-Assembled Monolayers on Microcantilever Biosensor
Authors: Chou Chia-Ching , Chang Shu-Wei , Chen Chuin-Shan
Published: January 2011

Microcantilever-based biosensors are rapidly becoming an enabling sensing technology for a variety of label-free biological applications due to their wide applicability, versatility and low cost. It is thus imperative for us to reveal the physical origin of adsorption-induced deformation, and to further analyze its implication of microscopic mechanisms on macroscopic deformation. In the paper, we study adsorption-induced surface stresses and microcantilever motion in alkanethiolate SAMs on Au surface. We develop a multiscale method that can analyze deformation of micro-cantilever beam subjected to bio-adsorption mechanisms calculated by ab-initio simulation and classical molecular dynamics. The adsorption mechanisms of different SAMs adsorbed on Au(111) surface, in the dry and liquid phase, are studied by ab-initio simulation and the adsorption-induced stresses are calculated through the multiscale method. The results give insight into the atomic forces and positions that play a key role in producing adsorption-induced surface stresses and resultant mechanical bending of microcantilevers.
Using Actuated Cilia to Regulate Motion of Microscopic Particles
Authors: Alexeev Alexander , Ghosh Rajat , Buxton Gavin A. , Usta O. Berk , Balazs Anna C.
Published: January 2011

Marine animals use microscopic elastic filaments, or cilia, to capture food particles that are suspended in the surrounding solution [1, 2]. In the respiratory tract, active cilial layers facilitate the transport of particulates such as dust or mucous. These motile cilia experience the surrounding fluid as a highly viscous, low Reynolds number environment, where the effects of inertia are negligible [2]. Nevertheless, by oscillating in a periodic, time-irreversible manner, the elastic cilia can generate net currents within the fluid and thereby, effectively transport and direct microscopic particles. The behavior of these biological cilia provides a useful design concept for creating microfluidic devices where actuated “synthetic cilia” would regulate the movement of micrometer-sized particles, such as biological cells and polymeric microcapsules.
A Hybrid Model for Nanoparticle Targeted Delivery in Blood Flow
Authors: Liu Yaling , Tan Jifu , Shah Samar
Published: January 2011

Nanoparticle targeted delivery in vascular system involves the interplay of transport, hydrodynamic force, and multivalent interactions with targeted biosurfaces. Current theoretical studies in nanoparticle therapeutic delivery are limited to nanoparticle suspensions in a Newtonian fluid without blood cells [1–3]. However, blood is a complex biological fluid made of components such as red blood cells (RBC), monocytes, platelets, proteins, etc. The existence of blood cells in the core region of blood streams might change the nanoparticle dispersion and binding through cell-nanoparticle interaction. It is thus important to understand how blood cells influence nanoparticles motion and binding.
Dynamic Manipulation and Precision Localization of Nanoparticles Internal to Cells
Authors: Tseng Peter , Judy Jack W. , Di Carlo Dino
Published: January 2011

Spatial localization of signals is commonplace within cells and allows for a variety of integral biological processes, including cell migration and polarization in development, neural synapse strengthening in learning, and correct cell division to avoid cancer development and progression. Despite the importance, few general tools have been developed to understand and probe spatial localization. We present a technique that translates the centimeter scale motions of an external magnet into nanometer scale motions of superparamagnetic nanoparticles internalized within cells growing on specially patterned “nano-active” substrates. In this way, localization of mechanical forces, or localization of nanoparticle-bound biomolecules can be controlled in real time.
Intracellular Trafficking of Nano-Carriers
Authors: Ferrati Silvia , Serda Rita E. , Bean Andrew , Ferrari Mauro
Published: January 2011

A multistage delivery system based on biodegradable mesoporous silicon particles loaded with one or multiple second stage nano-particles is likely to be useful for drug delivery. Upon intravenous injection the silicon nano-carriers will travel through the blood stream and migrate to the vessel wall. Vascular endothelial cells have been shown to be promising candidates for drug delivery as they represent both an anchor point and target.[1] It has been shown that human endothelial cells can act as nonprofessional phagocytes internalizing our silicon micron-sized nano-carriers.[2] The complete understanding of the molecular mechanisms required for the internalization of the particles into cells, as well as their fate once internalized, is crucial for the choice and formulation of appropriate second stage particles to be loaded in the silicon carrier. For example, different types of coatings or functionalization for both silicon nano-carriers and nano-particles could favor different trafficking pathways or promote endosomal escape following cellular uptake. In this study the uptake and trafficking of silicon nano-carriers in Human Microvascular Vein Endothelia Cells (HMVECs) was monitored using TEM, confocal microscopy and immunofluorescence.
PLLA-Nanodiamond Composites and Their Application in Bone Tissue Engineering
Authors: Zhang Qingwei , Neitzel Ioannis , Mochalin Vadym N. , Knoke Isabel , Wootton David M. , Gogotsi Yury , Lelkes Peter I. , Zhou Jack G.
Published: January 2011

Nanodiamond (ND) is an attractive nanomaterial for reinforcement of polymers [1] due to the ND’s superior mechanical and chemical properties, and low biotoxicity. A novel composite material has been produced for bone scaffolds utilizing the biodegradable polymer, poly(L-lactic acid) (PLLA), and octadecylamine-functionalized nanodiamond (ND-ODA) [2]. Composites were prepared by admixing to a PLLA/chloroform solution chloroform suspensions of ND-ODA at concentrations of 0, 1, 3, 5, 7, and 10 (w/w). Dispersion of ND-ODA in the composites was studied by transmission electron microscopy (TEM). The lower-resolution TEM micrograph of 1% wt ND-ODA/PLLA film (Fig. 1a) shows nanodiamond particles dispersed in PLLA film on amorphous carbon support. Due to long hydrocarbon chains of ODA the ND-ODA particles have good wettability with the PLLA so there is no segregation of ND-ODA and PLLA, and the polymer completely surrounds the particles. The high-resolution TEM image (Fig. 1b) shows ND crystals with attached organic material that can be ODA or PLLA. Nanoindentation tests show that the mechanical strength of ND-ODA/PLLA composites improves upon addition of ND (Table 1). Even at low concentrations (1% wt) the ND-ODA increased the hardness of the composite by 60% and Young’s modulus by 20% over neat PLLA. Based on our preliminary observations, we conclude that further additions of ND-ODA resulted in smaller changes with subsequent saturation in the mechanical properties at ∼7% wt (see Table 1). ND is relatively novel nanomaterial. Establishing its biocompatibility requires further studies, especially for modified ND. We studied the biocompatibility of 5–10nm ND and ND-ODA in experiments with a murine osteoblast cell line (7F2, from ATCC). Incubation of a cultured osteoblasts with 1–100μg/ml of ND or ND-ODA particles for 4 hours did not show much influence on the cell viability (Fig. 2), as inferred from an alamarBlue™ assay. To test the feasibility of ND-ODA/PLLA as a matrix material supporting cell growth, osteoblasts were cultured on the composites for 6 days. The attactment and proliferation of 7F2 cells on the scaffolds were assessed, respectively, by fluorescent nuclear staining with Hoechst 33258 and the alamarBlueTM assay. Our results showed that the addition of ND-ODA had only a negligibly small effect on cell proliferation, which is indicative of good biocompatibility of the composites (Fig. 3). The morphology of 7F2 cells growing on all ND-ODA/PLLA composite scaffolds was assessed by SEM. The data (not shown) confirm that the osteoblasts spread on the scaffolds similar to their spreading on TCP (tissue culture plastic). To summarize, the improved mechanical properties of the PLLA/ND-ODA composites and their good biocompatibility suggest that these materials may be suitable for applications in musculoskeletal tissue engineering.
A Platform Approach to Gene Delivery via Surface Modified Nanodiamonds
Authors: Zhang Xue-Qing , Chen Mark , Lam Robert , Xu Xiaoyang , Osawa Eiji , Ho Dean
Published: January 2011

The purpose of gene therapy is to introduce foreign genetic material into host cells to either supplement aberrant genes or to endow additional biological functions. To date, however, there has been only modest progress towards this goal, mainly due to the lack of safe, effective and broadly applicable delivery methods. Functional nanodiamonds (NDs) are rapidly emerging as promising platform carriers for next-generation therapeutics due to their innate biocompatibility, scalability, precise particle distribution, high surface area-to-volume ratio, near-spherical aspect ratio, and easily adaptable carbon surface for bioagent attachment. NDs have been functionalized with a range of therapeutics, proteins, antibodies, DNA, polymers, and other assorted biological agents. Furthermore, NDs are stable and dispersible in water, making them a promising and clinically important modality in improving the efficacy of the treatment of diseases and even some cancers at the molecular level. Mitochondrial function (MTT) and luminescent ATP production assays have demonstrated that NDs are not toxic to a wide variety of cell types. In this study, we functionalized NDs with amine groups via either covalent attachment of (3-aminopropyl) trimethoxysilane or surface immobilization of 800 Da low molecular weight polyethyleneimine (LMW PEI800) for plasmid DNA delivery. The latter delivery approach combines complementary characteristics of PEI800 and NDs to create a hybrid material that exhibits the high transfection efficiency of high molecular weight PEI, but without the inherent high cytotoxicity.
Bi-Directional AC Electroosmosis Micropump for Medical Applications
Authors: Islam Nazmul
Published: January 2011

The design, fabrication and control unit of a novel medical implant silicon micropump based on AC electroosmosis is presented in this research. The advent of microfabrication and integrated miniature pumps has applications on devices like implantable glucose sensors. These micropumps find their greatest applications in biomedical devices requiring the transport of small, accurately measured liquid quantities. Such types of micropumps can be programmed to administer insulin at a constant rate throughout the day, thus eliminating any surges or deficits of the drug in the patient’s bloodstream [1]. These micropumps can also be integrated with the lab-on-a-chip and can provide inexpensive, disposable devices. The strict performance requirements of medical devices call out for highly reliable micropump designs. To demonstrate the fluid manipulation in glucose sensor applications, an optimized and well-controlled biased AC electroosmotic micropump is developed using symmetrical electrode array. Experimental results also show that this kind of miniature pump has potential applications in portable infusion/suction systems.
Interactive Computer Aided Preliminary Design of Shell and Tube Heat Exchangers
Authors: Omar Hossin
Published: January 2011

The objective of this work is to develop an interactive computer aided preliminary design program for shell and tube heat exchanger based on the Bell (Delaware) method with internal evaluation of all required physical properties utilizing the best methods in the open literature known for their accuracy and reliability. FORTRAN90 is the program language used in this work. All mechanical and geometrical required data are internally evaluated. This program will be used to study the performance of Bell (Delaware) method by comparing the results obtained via this program with experimental data from industry. Cost estimates are to be generated by the program for all components, using very well known cost estimate techniques. Finally, the developed program was tested for accuracy and consistency against existing design cases from industry. The program was tested with other six experimental samples, and it was found that the program work accurately and the percentage of error in most parameters are in the allowable.
Oxyfuel PFBC-CC Power Generation Process
Authors: Deng Shimin , Hynes Rory
Published: January 2011

In this paper, a new power generation process based on oxyfuel and PFBC-CC is proposed, which has advantages in thermal performance, emissions and footprint. Five cases in total are modeled by using Aspen Plus™ and GateCycle™. The simulation indicates that the efficiency of the new process is 4% higher than existing ambient oxyfuel power generation process. The performance of the base case is compared with two existing oxyfuel cases to identify the potentials of the new process. Thermodynamic benefit of the new process is reasonably explained by introducing a concept of “non-stack combined cycle”. The waste heat recovery from gas turbine exhaust gas is discussed and compared. In addition, impacts on performance of key parameters are investigated.
Simultaneous Energy and Water Minimization: Approach for Systems With Optimum Regeneration of Wastewater
Authors: Karbassian Samira , Panjeshahi Mohamad Hassan
Published: January 2011

Water and energy are key commodities utilized in the process industries. In this work, a new systematic design methodology has been developed for the simultaneous management of energy and water systems that also feature optimum regeneration of wastewater. In addition to allowing regeneration of wastewater, issues about heat losses inside unit operations have also been incorporated in the simultaneous management of water and energy. To implement such a design, two new design aspects are introduced; new method for “Non-isothermal Mixing” points identification and new “Separate System” generation. The first aspect involves “non-isothermal mixing”, which enables direct heat recovery between water streams, and therefore allows the reduction of the number of heat transfer units. An NLP model is formulated to identify feasible non-isothermal mixing points in the network regarding minimum operation cost, which satisfy minimum freshwater and utility requirements. The other aspect is the generation of “separate system” in heat exchanger network design. The flexibility of mixing and splitting of water streams allows separate systems to be created as a cost-efficient series of heat exchanger units between freshwater and wastewater streams. The new design aspects have been illustrated with a case study. The results show 60% of total cost saving relevant to the conventional design method.
Retrofit of Tehran City Gate Station (C.G.S.No.2) by Using Turboexpander
Authors: Taheri Seresht Ramin , Khodaei Jalalabadi Hassan , Rashidian Babak
Published: January 2011

Worldwide energy crisis makes it necessary to optimize consumption. One of the fundamental ways to reduce energy consumption is recovery from wasted energy. This can be applied in oil, gas and petrochemical industries in which large amounts of energy waste occur. We can refer to gas transportation when there is a pressure reduction at natural gas pressure reducing stations. In common classic methods, this reduction is accomplished through regulators or throttle valves which the great amount of energy existing in pipelines lost by them. In this paper, it has been suggested to use expansion turbine for achieving pressure reduction, as well as energy recovery goals. In this regard, Tehran City Gate Station No.2 which is one of the large natural gas pressure reducing stations in Iran (both from capacity and inlet pressure perspectives), has been selected as a case study. In first step waste of energy was calculated by using exergy analysis and in second step, by using expansion turbines that are used parallel in the station for achieving the goals of gas reduction pressure and power recovery was simulated in four scenarios by Thermoflow1 software. The results show undeniable fact that the Energy loss at this station has been 38,443,578 KWhr for a year. As a result of using turboexpander, the exergy recovery will be 96%. At the final step, one scenario was selected as the best which its period of payback was about 2 years.
Influence of the Constraint Equations in the Thermo-Mechanics Stress Analysis in Blades of Gas Turbine
Authors: Pe´rez Garci´a Vicente , Gallegos Mun˜oz Armando , Rodri´guez Cruz Rafael A. , Belman-Flores Juan M. , Campos Amezcua Alfonso , Mazur Z.
Published: January 2011

The thermo-mechanical stresses analysis in an internally cooled first stage bucket, applying the finite element analysis (FEA) and computational fluid dynamics (CFD) is presented. In this analysis two cases are considered; first one where the model is solved using constraint equations in two zones, blade-platform and platform-root, obtaining the distribution of stresses which is in agreement with the physical problem, nevertheless due to the application of the constraint equations it was observed that the model has numerical limitations to obtain results. For the second case, without constraint equations, a geometry that include all the zones of the blade is achieved, generating a new mesh on which the same analysis was realized (thermo-mechanic) obtaining similar magnitudes of stresses like the first one model, but without numerical limitations. In both cases, the analysis was done using a complete model in 3D including the internal cooling channels. To carry out this analysis it was necessary to apply an interface FLUENT-ANSYS (FAI) to transfer the temperature data from an analysis obtained with a CFD model in steady state to the finite element model. A methodology was developed to eliminate to constraint equations in the finite element model across skills of union elements to achieve a uniform mesh in the whole model. The results show that an analysis without constraint equations, to avoid geometric simplifications and numerical limitations, permitting to obtain better results in the analysis of thermo-mechanics stress in blades of a gas turbine.
Wind Integration: System and Generation Issues
Authors: Danneman Eugene R. , Beuning Stephen J.
Published: January 2011

Intermittent availability of wind and solar power will require increased dispatch flexibility of conventional power plants to supply voltage support, frequency control, regulation and spinning reserves (ancillary services for regulation). Deep load follow ramp cycling and on/off state cycling will cause irreversible damage to conventional coal power plants. That damage must be managed to optimize unit reliability, fuel, variable O&M, emissions and maintenance capital investment costs. Wind Resources will play an important role in Xcel Energy’s future resource portfolio. The high levels of wind energy forecasted to be on line by 2020 will likely lead our utility to back down operations at some base load resources and require greater unit dispatch flexibility. These studies helped identify and estimate costs due to wear-and-tear caused by varying generating unit operation. The next step will involve optimizing total system costs using several solutions.
Change Your Maintenance Philosophy When You Convert a Base Loaded Unit to Cycling Operation
Authors: Palakodeti S. Rao , Doelger Gregory
Published: January 2011

With the fuel prices going up and many states mandating use of more renewable energy, a number of utilities are forced to convert some of their base loaded units to cycling operation. This change in operation requires a departure from the standard maintenance practices established for a given unit. This includes changes to Preventative Maintenance (PM), Predictive Maintenance (PdM), Planning and Scheduling and Key Performance Indicators (KPIs). When a unit is cycled — either minimum load to maximum load or two shift operation — it goes through stress cycles and its expected life decreases relative to the severity of cycling. When a decision is made to cycle a base loaded unit, the impact of the cycling has to be analyzed and the PM and PdM procedures need to be modified in order to maintain the expected life of the components. Cycling affects different components to different degrees and appropriate inspection and maintenance schedules need to be developed. The Key Performance Indicators (KPIs) have to be modified to monitor the effectiveness of the inspections and maintenance performed on the equipment. For example, Maintenance Basis Violation (MBV) is an important KPI for a cycling unit. Similarly, more attention has to be paid to the Planning and Scheduling activities as there are many uncertainties in the availability of the unit for preventative maintenance. The paradigm of performing PMs on a time basis should be changed to a throughput or hours of operation basis. This paper reviews the impact and severity of different cycling modes on a unit, vulnerability of common components adapting to the new mode, and discusses — in general terms — the required changes which need to be made in the inspection and maintenance practices. Also the paper reviews various KPIs that can be put in place for monitoring the impact of these procedures.
Rotating Drum Raw Water Strainer Fluid Mechanics and Debris Cleanout
Authors: Haber Ludwig C. , Smith James
Published: January 2011

McGuire nuclear station and Alden have completed an extensive computational and experimental study characterizing the operating fluid mechanics and debris clean out behavior of a rotating drum strainer. The raw water strainer is installed on the suction side of the nuclear service water (RN) system pump. The strainer consists of a cylindrical shell inside of which a rotating drum is installed that is equipped with approximately 1500 filter media openings. Process supply water spills through the rotating drum openings on its way to the RN pump suction inlet, thus removing debris greater than approximately 3/16″. As the drum loads with debris, the operating pressure drop through the drum increases. At a preset drum pressure drop level, the backwash supply system is activated and sprays water through two supply shoes into backwash exit channels from which the debris laden water can be evacuated. The study was initiated to determine fluid dynamics and debris clean-out performance under various conditions. With definitive operating mechanics identified, an improved drum clean-out procedure and system was developed. The study combined the strengths of analytical CFD modeling with extensive experimental validation and debris testing. The study has proven to be valuable to the plant engineering team to help reduce required backwash supply flow, backwash channel exit flow (and hence horsepower) and to conclusively demonstrate the cleaning capabilities of the installed rotating drum strainer design.
Design of an Experimental System for Cryogenic Compact Exchanger
Authors: Tang Jiancheng , Xie Yingbai
Published: January 2011

Heat exchanger is one of the most important devices in thermal system. An experimental system is developed for testing the heat-exchange performance of cryogenic compact exchangers. This system mainly consists of a regenerator, a cold box, a liquid nitrogen dewar, two cryogenic transfer lines and other devices. The features of the main components are described in this paper. A measurement system based on PC is developed for this system. All of these make this system more reliable, convenient, and energy-saving.
A Scalable, Economical, Uninterrupted Solar Thermal Power System
Authors: Bartlett Brent R. , McGeoch Bruce , Whitaker Edward , Torrey David A.
Published: January 2011

Recent years have seen a surge of interest in renewable energy sources. Most renewable energy sources are intermittent in their production of power. One solution is to store the energy and draw from that stored energy in a controlled fashion. Recent advances have been made in solar thermal storage that would allow a solar thermal power system to operate year round and around the clock at nearly constant levels of electrical power production. This paper outlines how this can be accomplished.
Preliminary Research of a Zero CO2 Emission Power Generation System
Authors: Ran Jing-yu , Qin Chang-lei
Published: January 2011

CO2 is a main greenhouse gas fazing the Earth. So countries around the world are actively studying the methods of capturing CO2 to reduce emission. In this paper, firstly a brief review was carried out on the research development and technical problems of three typical near-zero CO2 emission power generation systems. Focus was made on the construction of one possible commercially applied zero emission system, which has new principle but relatively conservative sections. Preliminary analysis and calculation of energy and mass flow have been finished to evaluate its performance. The results showed that apart from zero CO2 emission, a relatively tempting efficiency could be sustained. Theoretically, higher than 90% purity of CO2 and 63% generation efficiency of the whole system can be achieved.
Implementation of Fourier Series in the Seismic Response Spectrum Analysis of Ground Supported Tanks
Authors: Antaal Bikramjit Singh , Hari Yogeshwar , Williams Dennis K.
Published: January 2011

This paper describes the finite element considerations employed in a seismic response spectrum analysis of a ground supported, liquid containing tank. Like many axisymmetric cylindrical vessels, the gross seismic response to an input response spectrum can be categorized by a simplified lumped mass model that includes both the mass of the tank proper in combination with the associated mass of multiple fluid levels. This simplified response may be utilized to determine the initial sizing of the supporting configuration, but lacks the ability to properly address the fluid-structure interaction that creates sloshing loads on the tank walls. The most obvious method to address the fluid-structure interaction when considering the finite element method is to build a three-dimensional model of the tank, including, but not limited to the shell courses, the top and bottom heads (for a vertical vessel), and any tank supports. The inclusion of the fluid effects may now be incorporated with “contained fluid” finite elements, however, for tanks of any significant volume, the number of finite elements can easily exceed 100,000 and the number of degrees of freedom can sore from as few as 300,000 to as many as 500,000 or more. While these types of finite element analysis problems can be solved with today’s computer hardware and software, it is not desirable in any analysis to have that volume of information that has to be subjected to the nuclear QA environment (if at all possible). With these items in mind, the methodology described in this paper seeks to minimize the number of degrees of freedom associated with a response spectrum analysis of a liquid filled, vertical cylindrical tank. The input response spectra are almost always provided in Cartesian coordinates, while many, if not most liquid containing pressure tanks are almost always axisymmetric in geometry without having benefit of being subjected to an axisymmetric load (acceleration in this case) due to the specified seismic event. The use of harmonic finite elements for both the tank structure and the contained fluid medium permit the efficiencies associated with an axisymmetric geometry to be leveraged when the seismic response spectrum is formulated in terms of a Fourier series and combined to regain the effects of the two orthogonal, horizontally applied accelerations as a function of frequency. The end result as discussed and shown in this paper is a finite element model that permits a dense mesh of both the fluid and the structure, while economizing on the number of simultaneous equations required to be solved during the chosen finite element analysis.
SGT-400 Industrial Gas Turbine Power Enhancement to 15MW Design and Product Validation
Authors: Ward S. A. , Johnson-Hirt M.
Published: January 2011

The SGT-400 industrial gas turbine was launched in 1997 and is now a proven and mature product in the market place for both power generation and mechanical drive applications. Rated at a nominal power of 12.9MW (electrical) and 13.4MW (shaft), this gas turbine has achieved sales of more than 180 units and exceeded 1,300,000 fleet operational hours. The natural progression for the SGT-400 was to build on this experience by developing a power enhancement from the current rating to a 15MW class of engine. This paper describes the key design features of the power enhancement along with the steps taken to validate the product in a risk controlled manner. Existing proven product design complemented by new technological advancements has enabled a 12% increase in gross power output for the core engine. The latest design tools and methods result in a 15MW engine offering the highest efficiency in its class. The design upgrades to the existing gas turbine are predominantly in the compressor section which has been given an increased inlet annulus area to accommodate the extra massflow through the core. The 15MW gas turbine core maintains common interfaces with the package as the current rating, so can be retrofitted in earlier installations if required.
Using CFD to Improve the Thermal Characteristic Analysis Methodology of Dry Storage System for Chinshan Nuclear Power Plant
Authors: Tseng Yung-Shin , Wang Jong-Rong , Lin Chi-Hung , Shin Chunkuan , Tsai F. Peter
Published: January 2011

Chinshan Nuclear Power Plant (CSNPP) is a two-unit BWR4 plant with 1804MWt power per unit. Taipower Co., the owner of the plant is preparing the life extension procedure to extend the CSNPP operation time. In order to meet the life extension requirement, many issues need to be solved before life extension licensing, such as the spent nuclear fuel management, structure aging etc. For the spent nuclear fuel management, ROC Atomic Energy Council (ROCAEC) certified method is employed to analyze the thermal behaviors of Dry Storage System (DSS). This method uses ANSYS coupled with RELAP5-3D to solve the thermal characteristic and successfully accomplish the licensing procedure of the Chinshan Nuclear Dry Storage Project. However, further validation results demonstrate that the coupled method still exists uncertainty and deficiency. In this study, a new Computational Fluid Dynamics (CFD) numerical model for spend nuclear fuel (NSF) dry storage system (DSS) has been developed to improve the accuracy of DSS thermal analysis results. Its accuracy has been validated by comparing the temperature predictions with the experimental results of VSC-17 DSS. It has been found that the thermal behaviors and physical phenomena in the DSS could be predicted with good agreement for the measurements. Moreover, the uncertainty and reasonableness of results in previous method can be improved by the new thermal analyses methodology.
Colorless Distributed Combustion (CDC) With Swirl for Gas Turbine Application
Authors: Khalil Ahmed E. E. , Arghode Vaibhav K. , Gupta Ashwani K.
Published: January 2011

Colorless Distributed Combustion (CDC) can provide significant improvement in gas turbine combustor performance. CDC is characterized by uniform thermal field in the entire combustion chamber, thus avoiding hot-spot regions for low NOx emissions (thermal NOx) and significantly improved pattern factor. In this paper, colorless distributed combustion with swirl is investigated in detail to seek the beneficial aspects of CDC and swirl flows with focus on developing ultra low emissions of NO and CO, and much improved pattern factor. Experimental investigations have been performed using a cylindrical combustor with different modes of fuel injection, swirling air injection and gas exit stream location of the combustor. Air was injected tangentially to impart swirl to the flow inside the combustor. Results showed very low levels of NO (∼3PPM) and CO (∼70PPM) emissions at equivalence ratio of 0.7 at a high heat release intensity of 36MW/m3atm with non-premixed mode of combustion. Results have also been obtained on lean stability limit and OH* chemiluminescence under both premixed and non-premixed conditions.
Boiler Cleaning Using ISB (Intelligent Soot Blowing) System Integration: Recent Developments and Case Study
Authors: Breeding Charlie , Tandra Danny , Shah Sandeep
Published: January 2011

Ash and slag deposits in coal fired boilers contribute to boiler in-efficiency, capacity reductions, and overheated tubes, which lead to tube failures. Typical on-line cleaning systems are not automated and do not optimize the removal of ash and slag deposits. The paper describes the development and implementation of an Intelligent Sootblowing (ISB) system which monitors data such as heat transfer rate and pendant weight and operates the boiler cleaning devises in an automatic mode. The system operates cleaning equipment to only clean what needs to be cleaned, thus reducing tube erosion and clinker formation. The Intelligent Sootblowing (ISB) system uses the process data, algorithms, thermodynamic models, and ash weight to derive a supervisory sequence control to initiate most effective sootblowing device, when and where necessary. Unique strain gage ash weight measurement feedback is utilized in the system. The system is modular and built with an Open Architecture off the shelf components. It comprises PLC Panels, Data Acquisition Panels and HMI (Human Machine Interface) / EWS (Engineering Work Station) using distributed controls architecture. This system also supports industry standard communication protocols, which provides seamless integration between the ISB system and the plant’s DCS. This protocol can be Ethernet, Modbus, Modbus TCP, DH+ or Serial. The Case Studies will describe existing installations where the integrated system controls the entire boiler cleaning system. One installation is in Texas for an 850 MW, supercritical Combustion Engineering tangential fired pulverized coal unit. The boiler burns Texas lignite coal with as much as 15% Powder River Basin coal blended. The soot blowing system consists of 50 retractable soot blowers and 8 water cannons plus air heater cleaners. Testing for this unit was supervised by EPRI. A second installation is in Louisiana where the system improved overall plant efficiency as much as 1% with a resulting high return on investment. Improvements also included improved heat rate, boiler efficiency, a reduction in spray flow and a reduction in soot blowing events.
Critical review: Plasma-surface reactions and the spinning wall method
Authors: Donnelly V. M. , Guha J. , Stafford L.
Published: January 2011

This article reviews methods for studying reactions of atoms and small molecules on substrates and chamber walls that are immersed in a plasma, a relatively unexplored, yet very important area of plasma science and technology. Emphasis is placed on the “spinning wall” technique. With this method, a cylindrical section of the wall of the plasma reactor is rotated, and the surface is periodically exposed to the plasma and then to a differentially pumped mass spectrometer, to an Auger electron spectrometer, and, optionally, to a beam of additional reactants or surface coatings. Reactants impinging on the surface can stick and react over time scales that are comparable to the substrate rotation period, which can be varied from ∼0.5 to 40 ms. Langmuir–Hinshelwood reaction probabilities can be derived from a measurement of the absolute desorption product yields as a function of the substrate rotation frequency. Auger electron spectroscopy allows the plasma-immersed surface to be monitored during plasma operation. This measurement is critical, since wall “conditioning” in the plasma changes the reaction probabilities. Mass spectrometer cracking patterns are used to identify simple desorption products such as Cl2, O2, ClO, and ClO2. Desorption products also produce a measurable pressure rise in the second differentially pumped chamber that can be used to obtain absolute desorption yields. The surface can also be coated with films that can be deposited by sputtering a target in the plasma or by evaporating material from a Knudsen cell in the differentially pumped wall chamber. Here, the authors review this new spinning wall technique in detail, describing both experimental issues and data analysis methods and interpretations. The authors have used the spinning wall method to study the recombination of Cl and O on plasma-conditioned anodized aluminum and stainless steel surfaces. In oxygen or chlorine plasmas, these surfaces become coated with a layer containing Si, Al, and O, due to slow erosion of the reactor materials, in addition to Cl in chlorine plasmas. Similar, low recombination probabilities were found for Cl and O on anodized Al versus stainless steel surfaces, consistent with the similar chemical composition of the layer that forms on these surfaces after long exposure to the plasma. In chlorine plasmas, weakly adsorbed Cl2 was found to inhibit Cl recombination, hence the Cl recombination probability decreases with increasing Cl2-to-Cl number density ratios in the plasma. In mixed Cl2/O2 plasmas, Cl and O recombine to form Cl2 and O2 with probabilities that are similar to those in pure chlorine or oxygen plasmas, but in addition, ClO and ClO2 form on the surface and desorb from the wall. These and other results, including the catalytic enhancement of O recombination by monolayer amounts of Cu, are reviewed.
Effect of vacuum ultraviolet and ultraviolet irradiation on mobile charges in the bandgap of low-k-porous organosilicate dielectrics
Authors: Sinha H. , Nichols M. T. , Sehgal A. , Tomoyasu M. , Russell N. M. , Antonelli G. A. , Nishi Y. , Shohet J. L.
Published: January 2011

Capacitance-voltage (C-V) measurements are used to determine the effect of vacuum ultraviolet (VUV) and ultraviolet irradiation on mobile charges in porous low-k organosilicate (SiCOH) dielectrics. Hysteresis in the C-V characteristics shows that VUV irradiation increases the number of mobile charges in the dielectric. This is because VUV photons excite the trapped electrons from defect states to make them mobile carriers. Conversely UV reverses this effect by reducing the mobile charges through photoemission of free electrons and repopulation of trap states. Thus UV irradiation can be used to improve the electrical properties of plasma-processed dielectrics that are subjected to VUV irradiation.
Synchrotron photoemission studies on reconstructed strained surfaces
Authors: Kim Hidong , Li Huiting , Duvjir Ganbat , Seo Jae M.
Published: January 2011

Recently, based on scanning tunneling microscopy studies of the reconstructed Si(5 5 12)−2×1 surface, it has been suggested that its unit cell simply consists of four kinds of one-dimensional (1D) structures: π-bonded (π) chain, honeycomb (H) chain, tetramer (T) row, and dimer-adatom (D-A) row. In the present study, by angle-resolved ultraviolet photoelectron spectroscopy, it has been found out that the Si(5 5 12)−2×1 surface has two kinds of surface states, one with a negligible dispersion originating from row structures (T/D-A) and the other with a strong dispersion originating from chain structures (π/H). Also, the Si 2p core-level spectrum shows at least two kinds of surface components, one with 0.23 eV higher binding energy originating from upward-relaxed surface atoms and subsurface atoms, and the other with 0.52 eV lower binding energy originating from downward-relaxed surface atoms. It can be realized that these spectroscopic results quantitively match with the structural model of Si(5 5 12)−2×1 having four kinds of 1D structures.
Structure and properties of ZrN coatings deposited by high power impulse magnetron sputtering technology
Authors: Purandare Y. P. , Ehiasarian A. P. , Hovsepian P. Eh.
Published: January 2011

Monolayer ZrN coatings were deposited exclusively by the novel high power impulse magnetron sputtering (HIPIMS) technology in an industrial scale physical vapour deposition (PVD) machine (HTC-1000-4 target system). Coatings were deposited on 1 μm polished M2 high speed steel, on 304L stainless steel (SS), and on Si (100) specimens. Prior to deposition, HIPIMS plasma sustained on a zirconium (Zr) target was utilized to pretreat the specimens. Coatings were deposited at 400 °C in a mixed N2 and Ar atmosphere using 2 magnetrons in HIPIMS mode and at three different substrate bias voltages (Ubias) keeping all other process parameters constant. The thicknesses of the coatings measured by the ball cratering technique were in the ranges of 1.84, 1.96, and 2.13 μm at bias voltages of −95, −75, and −65 V, respectively, where the difference in thickness can be attributed to the resputtering effect. X-ray diffraction experiments on SS specimens revealed a dominating 111 texture for all three coatings irrespective of the bias voltage. Cross-sectional transmission electron microscopy revealed extremely dense coating structures at all bias voltages, similar to the transition zone structure (zone T) reported by Thornton. The −95 bias voltage coatings appeared extremely smooth on the top and with no dome shaped structures often associated with low ion bombardment during deposition. HIPIMS pretreatment leads to high adhesion (LC) of the coatings to the substrate. A continuous ductile perforation of the coating was observed at progressive loads greater than 65 N; however, no spallation of the coating was observed up to loads of 100 N. High values of hardness (40.4 GPa), Young’s modulus (424 GPa), and compressive stress (10 GPa) were recorded for coatings deposited at −95 BV. The hardness and internal stress of the coating were found increasing with more negative bias voltages. All the coatings exhibited high dry sliding wear resistance (KC) in the range 6×10−15 m3 N−1 m−1. Cross-sectional transmission electron microscopy and atomic force microscopy analyses have been used to study the effect of ion bombardment obtained from HIPIMS on the structure of the coatings.
Spatially resolved measurements of ion density and electron temperature in a dual-frequency capacitively coupled plasma by complete floating double probe technique
Authors: Jiang Xiang-Zhan , Liu Yong-Xin , Yang Shuo , Lu Wen-Qi , Bi Zhen-Hua , Li Xiao-Song , Wang You-Nian
Published: January 2011

Spatially resolved measurements of the ion density and electron temperature in a dual-frequency capacitively coupled Ar discharge plasma are performed with a newly developed complete floating double probe. Axial and radial distributions of the ion density and electron temperature under various high-frequency (HF) power and gas pressure were studied in detail. Both the ion density and the electron temperature increased with increasing HF power. With increasing gas pressure from 1.3 to 9.3 Pa, the radial profile of ion density below the driven electrode experienced a change from “bimodal” to “unimodal” shape, with better uniformity being achieved at the optimal pressure of about 5 Pa. In addition, changing the axial profile of ion density was also observed with the peak shift toward the powered electrode at higher pressures. The measured results showed satisfying consistency with that of improved two dimensional fluid simulations.
Design and fabrication of a novel microgripper with four-point contact fingers
Authors: Zheng Xiaohu , Kim Ji-Kwan , Lee Dong-Weon
Published: January 2011

A novel microgripper with four-point contact fingers is introduced. It consists of four fingers suspended on the diagonal lines of a square frame in the end of the main cantilever structure located on the silicon substrate. The initial gap between the tips is 20 μm and can be decreased depending on the fabrication techniques. Lightly doped silicon works as the electric-thermal resistor to make the fingers deflect according to the different expansions between the metal layer covered on the top surface and the silicon substrate. The V-grooved pattern on the finger surface could help the finger to generate a larger vertical displacement. The finger tip could move from a “closed” position to an open one by regulating the driven voltage so as to grip and elevate the micro-object. A mathematical model of heat transfer is built up to analyze the temperature contribution of the finger. The displacement and temperature distribution on the finger was simulated by using finite element method software. Then the key fabrication process and its working performance were experimentally evaluated. A satisfactory match between experimental test and finite element simulations was obtained. The results indicate that the new microgripper has a good performance and further potential application in micromanipulation.
Selective Advantage of Resistant Strains at Trace Levels of Antibiotics: a Simple and Ultrasensitive Color Test for Detection of Antibiotics and Genotoxic Agents
Authors: Liu Anne , Fong Amie , Becket Elinne , Yuan Jessica , Tamae Cindy , Medrano Leah , Maiz Maria , Wahba Christine , Lee Catherine , Lee Kim , Tran Katherine P. , Yang Hanjing , Hoffman Robert M. , Salih Anya , Miller Jeffrey H.
Published: January 2011

Many studies have examined the evolution of bacterial mutants that are resistant to specific antibiotics, and many of these focus on concentrations at and above the MIC. Here we ask for the minimum concentration at which existing resistant mutants can outgrow sensitive wild-type strains in competition experiments at antibiotic levels significantly below the MIC, and we define a minimum selective concentration (MSC) in
Escherichia coli
for two antibiotics, which is near 1/5 of the MIC for ciprofloxacin and 1/20 of the MIC for tetracycline. Because of the prevalence of resistant mutants already in the human microbiome, allowable levels of antibiotics to which we are exposed should be below the MSC. Since this concentration often corresponds to low or trace levels of antibiotics, it is helpful to have simple tests to detect such trace levels. We describe a simple ultrasensitive test for detecting the presence of antibiotics and genotoxic agents. The test is based on the use of chromogenic proteins as color markers and the use of single and multiple mutants of
Escherichia coli
that have greatly increased sensitivity to either a wide range of antibiotics or specific antibiotics, antibiotic families, and genotoxic agents. This test can detect ciprofloxacin at 1/75 of the MIC.