bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of the Diffusion of Doxorubicin (DOX) in Polymer Pores for a Multiscale Nanodiamond Based Drug Delivery System
Authors: Arendt Paul D. , Chen Wei , Liu Wing Kam
Published: January 2011

A drug delivery system utilizing nanodiamonds has been proposed for the controlled release of the chemotherapeutic doxorubicin (DOX) [1,2]. The drug delivery system consists of a patch which is envisioned to be implanted immediately after a tumor removal surgery to target residual cancerous cells such that tumor reoccurrence can be effectively prevented. Therefore, long release times are desired for the patch to prevent any new cancerous tissue from forming. The patch is to be assembled in three different layers beginning with a bottom layer comprised of nonporous parylene. A layer of DOX loaded nanodimonds is deposited onto the base layer. Then a porous layer of parylene is accumulated on top of the nanodimonds. Nanodimonds are utilized because their release rates are based on pH, which changes near cancerous cells. Due to the complexity of the drug delivery system, models are created at several different scales.
Enhanced Tumor Cell Separation by Surfaces Functionalized With Combinations of Bioadhesive Proteins
Authors: Myung Ja Hye , Launiere Cari A. , Gajjar Khyati A. , Eddington David T. , Hong Seungpyo
Published: January 2011

Effective detection of circulating tumor cells (CTCs) can provide important diagnostic and prognostic information of metastatic cancer. However, CTCs are extremely rare and estimated to be only in the range of one tumor cell in the background of 106–109 normal blood cells, hindering clinically significant detection.[1–2] The specific capturing and potential enrichment of CTCs using anti-epithelial cell adhesion molecule (anti-EpCAM)[3] and selectin, respectively, inspire a biofunctionalized surface that mimics biological complexity may detect and isolate target cells at a greater sensitivity and specificity. This concept is supported by the initial physiological interactions between CTCs and endothelium in the bloodstream, which include concurrent rolling and stationary binding steps. Towards this aim, we investigated the following: i) two proteins with distinct biofunctions (selectin to induce rolling and anti-EpCAM to statically capture target cells) can be co-immobilized; ii) a combined rolling and stationary binding can be induced by the mixture of the proteins; and iii) the biomimetic combination enhances overall capture efficiency of the surface. As a proof-of-concept study for the hypothesis of enhanced separation capacity and capture efficiency using protein mixtures, the surfaces are tested using in vitro cell lines (MCF-7 cells as a CTC model and HL-60 cells as a leukocyte model) under flow conditions. The effects of the combination of rolling (E-selectin) and stationary binding (anti-EpCAM) on capture efficiency are compared to a surface functionalized solely with anti-EpCAM.
DNA: Not Merely the Secret of Life
Authors: Seeman Nadrian C.
Published: January 2011

DNA is well-known as the genetic material of living organisms. Its most prominent feature is that it contains information that enables it to replicate itself. This information is contained in the well-known Watson-Crick base pairing interactions, adenine with thymine and guanine with cytosine. The double helical structure that results from this complementarity has become a cultural icon of our era. To produce species more diverse than the DNA double helix, we use the notion of reciprocal exchange, which leads to branched molecules. The topologies of these species are readily programmed through sequence selection; in many cases, it is also possible to program their structures. Branched species can be connected to one another using the same interactions that genetic engineers use to produce their constructs, cohesion by molecules tailed in complementary single-stranded overhangs, known as ‘sticky ends.’ Such sticky-ended cohesion is used to produce N-connected objects and lattices [1]. This notion is shown in the drawing, which shows cohesion between sticky-ended branched species.
Highly Paramagnetic Tumor-Targeted Contrast Agents
Authors: Tsourkas Andrew
Published: January 2011

The noninvasive imaging of cell surface markers could provide a powerful technique for the early identification of cancer as well as allow for repetitive measurements to monitor the efficacy of therapeutic treatments. Magnetic resonance (MR) is a particularly attractive platform for molecular imaging due to the ability to acquire high-resolution anatomical images in conjunction with measures of biomarker expression; however, the sensitivity of MR contrast agents is often too low to detect the relatively low number of cell receptors per imaging voxel at the targeted site. To generate the level of sensitivity required for imaging molecular markers of disease, novel approaches must be established to amplify the MR signal. In this talk, we will describe how nanoparticulate carriers can be designed to carry extremely high gadolinium (Gd) payloads in order to compensate for the low MR signal enhancement generated by individual Gd ions. Further, we will show that Gd-labeled nanoparticles that have been functionalized with targeting ligands can be used for the highly sensitive detection of human tumor xenografts in mice.
Knockdown of SHP-1 Enhances Endothelial Cell Retention for Vascular Regeneration
Authors: Tefft Brandon J. , Kopacz Adrian M. , Liu Wing Kam , Liu Shu Q.
Published: January 2011

Atherosclerosis is the leading cause of morbidity and mortality in the developed world. A common treatment option is arterial bypass surgery, which requires the use of a vascular graft. Autologous vein is the current gold standard for use as a vascular graft; however, donor site morbidity and inconsistent availability have provided an impetus to explore alternative graft sources.
Integrated Diagnostics for Rapid Quantitation of Biomarkers in Human Fluids
Authors: Hou Chenlu , Karns Kelly , Herr Amy E.
Published: January 2011

A fast, accurate differential diagnosis is a tremendous challenge in clinical medicine. For example, in emergency settings differential diagnosis of infection from inflammation is needed, as a timely and actionable diagnosis is critical. Consequently, diagnostics capable of measuring multiple biomarkers would support clinical decision-making related to diagnosis, containment, and treatment. Microfluidic assays are exceptionally well-suited for near-patient clinical diagnostics (i.e., ambulance, emergency room, field hospital). We present spectrally multiplexed homogeneous electrophoretic immunoassays for specific protein disease biomarkers. Biomarkers are resolved quickly (< 60 s), in ultra-short separation lengths (< 1 mm), and at clinically relevant concentrations (nM). On-going work will be presented and centers on endogenous protein measurements in clinical samples in support of near-patient assessment.
Unnatural Amino Acids Modified Clays for Design of Scaffolds for Bone Tissue Engineering
Authors: Katti Kalpana S. , Katti Dinesh R. , Ambre Avinash H.
Published: January 2011

Here, we incorporate the results of our new “altered phase theory” (Sikdar et al. 2008a) into design of new polymer clay nanocomposites (PCNs) for bone biomaterials applications. Montmorillonite (MMT) clay was modified using unnatural amino acids as potentially new biocompatible modifiers. The longer carbon chain structures of the unnatural amino acids are expected to enhance non bonded interactions with clay as well as maintaining the usefulness of functional groups of natural amino acids. The specific choice of amino acids is based on both the antibacterial activity reported in literature and also our previous studies on role of chain length, functional groups etc of modifiers in influencing mechanical behavior in PCNs. Biocompatibility studies using cell culture experiments as well as mechanical behavior is evaluated for the PCNs. FTIR spectroscopy is used to compare changes to molecular structure. The increase in d001 spacing of modified clay compared to pure clay obtained from XRD experiments confirms successful intercalation of modifier. The osteoblast cells were found to grow and proliferate over the substrates. The major contribution of this work is the design of novel amino acid biopolymer-clay nanocomposites for biomaterials applications. Porous scaffold structures were also designed and fabricated.
Factors Affecting the Assembly of Carbon Nanostructures With Cells and Enzymes
Authors: Mazumder Sonal , Ghosh Suvojit , Falkinham Joseph O. , Puri Ishwar K.
Published: January 2011

Carbon nanostructures were synthesized and deposited through flame synthesis on stainless steel grids and foils, and on bare and ferrofluid-painted silicon wafers at different nonpremixed flame locations to produce hydrophobic surfaces. The hydrophobicity is characterized through the contact angle for water droplets placed on the surface. The surface morphology of the nanoparticles is obtained from high-resolution FESEM images. Following synthesis and deposition the adherence, activity, and stability of bacterial cells, antibodies, and enzymes on the carbon nanostructures can be studied.
Structure and Surface Properties of Nanodiamonds: A First-Principles Multiscale Approach
Authors: Datta Aditi , Fu Yao , Kirca Mesut , To Albert
Published: January 2011

The goal of this work is to gain fundamental understanding of the surface structure of functionalized detonation nanodiamonds (NDs) using quantum mechanics (QM) based multiscale modeling and simulation. The study entails a multiscale approach to bridge the length scale between the real sizes of ND being fabricated (∼4 nm) and the size allowed by employing first-principles based modeling (< 1 nm). At first, the structure of NDs of technologically relevant size (∼4 nm) was optimized using classical mechanics based molecular mechanics simulations. QM based density functional theory (DFT) was then employed to simulate the structure and analyze the properties of relevant parts of the optimized cluster. This work is extended to NDs functionalized with carboxylic acid (-COOH) and carbonyl oxygen (=O), which help to guide further experiments on functionalization of NDs and their use as carriers of drug molecules to the desired site.
Nanomechanics of Electrospun Fibers for Tissue Engineering
Authors: Baker Stephen , Sigley Justin , Carlisle Christine , Stitzel Joel , Berry Joel , Bonin Keith , Guthold Martin
Published: January 2011

Understanding the material properties of the nanofibers comprising electrospun scaffolds for tissue engineering will elucidate the mechanotransduction of cells seeded onto and attached those scaffolds. The overall mechanical properties of any structure built from fibers depend on 1) the architecture, 2) the properties of the constituent single fibers, and 3) the junctions between fibers. All three must be known to design a structure with predictable mechanical properties. We hypothesize that a basic understanding of the nanolevel mechanical properties of individual electrospun fibers will enable accurate prediction of the overall cellular response and bulk mechanical behavior of electrospun tissue scaffolds.
‘ONCOSENSOR’ for Noninvasive High-Specificity Breast Cancer Diagnosis by Carbogen-Enhanced Neutron Femto-Oximetry
Authors: Maglich Bogdan C. , Nalcioglu Orhan
Published: January 2011

Based on the first experiment on Differential Femto Oximetry (Paper 13270), we conducted a computer simulated study of the feasibility of conceptual design for our noninvasive malignancy probe, Oncosensor, to diagnose hypoxia of malignancy M = −0.90, measured by pO2 — which correspond to volume averaged hypoxia M′ = −0.09 — in 1cm, 3 cm and 5 cm DIA tumors embedded in the middle of a 10 cm DIA breast. M′ is further masked by background γ’s from the in vivo tissue by factor x = 4.4–7 for subcutaneous and central tumor, respectively, to apparent M″ = M′/X which, in turn, renders hypoxia non-diagnosable for 1 cm tumors; marginally so for 3 cm ones with specificity S = 75%, and fully diagnosable with S = 95% in 5 cm ones. To diagnose 1–3 cm and smaller tumors, we propose to enhance M″ by a factor of ≈ 3 by replacing air breathing with that of Carbogen (O2 95%, CO2 5%). With carbogen breathing, simulations predict hypoxia detection in 1 cm subcutaneous tumor with S = 68%, and in 3 cm ones with S = 95–99.9%. Carbogen renders possible 2 additional diagnostic tests for redundancy. Significant improvements of the above measurement accuracies are projected. Oncosensor will be tested in vivo with R3230 tumors in Fischer rats at UCI’s Center for Functional Onco-Imaging. Oncosensor requires imaging guidance.
Electrospun Polycaprolactone-Nanodiamond Composite Scaffolds for Bone Tissue Engineering
Authors: Salaam Amanee D. , Dean Derrick
Published: January 2011

Every year, there are roughly 8 million bone fractures in United States [1]. In addition, approximately 2300 new cases of primary bone cancer are diagnosed each year [2]. Yet, the number of people suffering from bone disease is significantly greater; about 10 million people in the U.S. alone suffer from osteoporosis [3]. Consequently, surgeons perform nearly 500,000 bone graft operations annually making bone grafts the second most frequently transplanted materials [4]. Although there is an extremely high demand for treatment of bone abnormalities, the current grafting methods fail to meet these demands due to several limitations. Autografting has the fewest problems with rejection and pathogen transmission, however in some cases the availability may be limited or not be possible (e.g., genetic diseases). With other methods of transplantation such as allogafting and xenografting where tissue is acquired from other humans or species, respectively, the receptor’s immune system causes an increased risk of chronic rejection [5]. Notably, the major drawback with all these methods is that they often require multiple painful and invasive surgeries.
Design and Optimization of a Nanotip Sensor via Immersed Molecular Electrokinetic Finite Element Method
Authors: Kopacz Adrian M. , Liu Wing K. , Chung Jae-Hyun
Published: January 2011

A critical challenge in the field of medicine is to develop a low cost sensor competent of detecting specific bacterial pathogens via a precise deoxyribonucleic acid (DNA) sequence. In order to identify such biological agents in a patient’s blood or other bodily fluids at the onset of infection, detection of specific pathogen genomic DNA is considered a reliable approach. Current techniques involving multiplex DNA/RNA detection arrays or immunoassays [1] require cumbersome sample preparation, aggressive nucleic acid amplification protocols and must be operated by trained personnel. To overcome the aforementioned obstacles, a time-dependent dielectrophoretic force driven sensor consisting of nanostructured tip is being developed.
A Microfluidic Assay for Metastasis Potential Analysis
Authors: Rao Smitha M. N. , Tata Uday , Lin Victor K. , Hsieh Jer-Tsong , Nguyen Kytai , Chiao J. -C.
Published: January 2011

We have designed and characterized a poly-dimethyl-siloxane (PDMS) based microfluidic device called MiMiC™ that enables time-lapse study of cell migration. Cell migration is a key step of malignant metastasis during cancer progression. The device mimics the narrow confines the cells need to traverse and the microenvironments that are similar to the ones inside human body. Photolithography and soft lithography processes were used to fabricate the microfluidic devices. The device consists of two separate chambers connected by microfluidic channels allowing introduction of cells in one chamber and chemoattractants in the other. The response of lung-metastasized prostate cancer (PC-3-ML) cells and their migration response to chemoattractants were observed and analyzed. The numbers of cells under migration were determined from time-lapse images and compared to control groups. Our microfluidic assays provide advantages over the traditional Boyden chambers such as time-lapse observation, use of smaller amounts of reagents and direct assessment of cells under migration.
Multimodality and Advanced Biomedical Imaging for Clinical and Research Applications
Authors: Bidaut Luc
Published: January 2011

Driven in particular by the availability of ever more refined imaging modalities — such as faster and higher resolution CT and MR, or hybrid PET/CT and SPECT/CT — and by a marked increase in computing power, advanced biomedical imaging — e.g. through its multidimensional and multimodal paradigms — is taking an ever bigger place in both research and clinical routine, and for both diagnostic applications and therapy management. While human modalities are widely publicized, there is a similar plethora of imaging systems for small animals, which permits relatively fast translation of successful image-based protocols from research evaluation to the clinic. Because of their characteristics and the need for more detailed information about normal vs. diseased tissues, modern modalities produce huge amounts of information and images. The only way to digest these is through advanced paradigms that combine or reduce the complexity of the information so that it can be interpreted by normal human beings. This presentation will introduce techniques and research or clinical applications of advanced imaging for both animals and humans.
Fabrication of Single-Crystal Nanospherical Hydroxyapatite Powder for Biomedical Applications
Authors: Honarmandi Peyman
Published: January 2011

The competence and compatibility of biomaterials is always challenging and demanding in biotech industries. Hydroxyapatite (HAp) is a useful biomaterial for biological applications due to its especial properties. In this paper, a dry mechanochemical process is introduced to produce hydroxyapatite nanoparticles. Structural and morphological properties of HAp powder are studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the single-crystal HAp nanospherical particles are successfully produced during milling process. Two different metallic and polymeric vials are applied and the results are compared for both vials. The results verify that the HAp nanoparticles are single crystal and their sizes are in the ranges of 12–24 nm.
Novel Biomimetic Scaffold for Tendon/Ligament Tissue Engineering
Authors: Allee Tyler J. , Li Wan-Ju
Published: January 2011

An emerging approach to repair and replace a great number of the ligament and tendon injuries that occur each year is the use of tissue engineering principles to fabricate replacement tissues. One of the current challenges in tendon/ligament tissue engineering is fabricating scaffolds that possess both the proper mechanical and biological properties. A promising strategy to produce such scaffolds is electrospinning. Electrospinning uses a high-voltage power supply to draw viscous polymer solutions into ultra-fine fibers with nanometer-scale diameters, thus structurally mimicking native extracellular matrix components, such as collagen fibrils. Nano-scale fibers have been previously shown to enhance cellular proliferation, as well as stimulate cells to maintain morphology and phenotype when compared to scaffolds composed of larger fibers [1]. Furthermore, electrospinning provides researchers the flexibility of fabricating aligned scaffolds with isotropic mechanical properties to mimic native tissue mechanics [2]. However, scaffolds composed of aligned electrospun nanofibers often do not possess the elasticity and tensile strength required to properly carry out the mechanical function of tendon/ligament tissues. One approach that has been used to enhance mechanical properties of fibrous scaffolds is to weave multiple fibrous bundles into a braided scaffold. [3]. In this study, we fabricated a novel tendon/ligament tissue engineering scaffold that combines enhanced biological properties of electrospun scaffolds with enhanced mechanical properties through braiding. Furthermore, our approach offers the versatility to tailor tensile strength and elasticity of the braided scaffolds simply by varying the pattern of braiding, making it possible for researchers to construct tendon/ligament scaffolds with various mechanical properties.
Functional Nanodiamond Internalization Mechanisms and Kinetics
Authors: Lam Robert , Zhang Xueqing , Chen Mark , Ho Dean
Published: January 2011

Several reports have described the relationship between size, aspect ratio, surface modification and internalization for a variety of nanoparticles (i.e. gold, polymer, carbon nanotubes). Nanodiamonds (NDs) in particular have recently been implicated in a variety of biomedical applications. One of the most promising is in utilizing NDs as drug delivery carriers where successful internalization is of utmost importance. A few reports recently have demonstrated the energy dependent internalization of bare NDs. In this report, we investigate the internalization mechanism and kinetics of functional ND-conjugate translocation.
Engineering Dense Connective Tissues via Anisotropic Nanofibrous Scaffolds With High Sacrificial Fiber Content
Authors: Baker Brendon M. , Silverstein Amy M. , Mauck Robert L.
Published: January 2011

Given their ability to dictate initial cell alignment and subsequent matrix organization, aligned electrospun scaffolds are a fitting means for engineering fiber-reinforced, anisotropic tissues such as tendon, ligament, the knee meniscus, and the annulus fibrosus [1–4]. However, one commonly observed limitation of such scaffolds is the relatively slow infiltration rates of surface-seeded cells, where the central thicknesses of constructs cultured for 10 weeks remain devoid of cells [3]. This limitation arises from the tight packing of fibers which yields small pore sizes, thereby hampering cell migration. Towards accelerating cell ingress, we have recently reported on two-polymer composite scaffolds containing both slow eroding poly(ε-caprolactone) (PCL) fibers as well as water-soluble poly(ethylene oxide) (PEO) fibers that serve as space holders during scaffold formation [5]. Removal of these PEO fibers prior to seeding resulted in improved cell infiltration after 3 weeks, but the long-term maturation of such constructs has yet to be characterized. To assess the effect of sacrificial PEO fiber content on construct growth, a triple-jet electrospinning device was employed to generate PCL/PEO scaffolds with PEO fiber fractions ranging from 0 to 60%. After seeding with human meniscus fibrochondrocytes (hMFCs), constructs were clamped in custom grips to maintain strip morphology. The mechanical and biochemical maturation of constructs was assessed over 12 weeks of free swelling culture in a chemically defined medium (CDM), along with cell infiltration and matrix distribution. We hypothesized that enhanced pore size in dual-fiber constructs would lead to not only to a better distribution of cells, but also to larger increases in stiffness resulting from enhanced matrix production and distribution.
An Electrochemical Dopamine Sensor Based on a Flexible Conductive Film of Single-Wall Carbon Nanotubes (SWCNT) on PET
Authors: Hamdi Naser , Tolosa Vanessa , Monbouquette Harold , Rahy Abdelaziz , Yang Duck Joon
Published: January 2011

This study investigates the potential application of a non-conventional substrate, a polyethylene terephthalate (PET) film treated with single-wall carbon nanotubes (SWCNT), as a dopamine sensor. The flexible and conductive SWCNT/PET substrate proved to be a sensitive dopamine sensor; it exhibited an excellent S/N ratio, good resistance to fouling, and rapid response characteristics. This approach may potentially be combined with screen-printing technologies for the production of conductive and flexible micro-electrode arrays with a multitude of biomedical sensing and point-of-care diagnostic applications.
A New Platform for Profiling Active Proteases With Single-Molecule Sensitivity
Authors: Satog˘lu Dog˘an M. Yu¨sra , Revyakin Andrey , Park Sang , Pertsinidis Alexandros , Brown Christopher , Chu Steven , Craik Charles S. , Majumdar Arun
Published: January 2011

Proteases, such as urokinase plasminogen activator (uPA) and prostate specific antigen (PSA), have been used extensively as biomarkers for cancer. A necessary improvement in diagnostics with proteomics is to use the activity levels of proteases as a signal, as opposed to the total protease content. This will provide a better functional insight into the propagation of cancer, and ultimately could allow us to diagnose cancer at earlier stages. Here, we propose a new platform to capture and measure activity of specific proteases in patient samples, with single-molecule sensitivity.
Bull Run Fossil Plant: Technical Design Methods for Superheat Pendant Outlet Headers Replacement
Authors: Azzazy Salah E. , Cochran Russell D. , Cox Larry Sam
Published: January 2011

Bull Run Unit 1, rated at 950 MW, is the first of four fossil supercritical power plants at Tennessee Valley Authority (TVA). The unit went into commercial operation in 1967. The boiler (consists of two furnaces) built by Combustion Engineering (CE) has a radiant reheat twin divided furnace with tangential-fired coal burners. The unit’s maximum continuous rating (MCR) is 6,400,000 lbs/hr of main steam flow, with a design temperature of 1003°F and pressure of 3840 psig. Through the end of 2008, the unit had a total of approximately 670 cumulative starts and 333,185 operating hours. After years of numerous tube cracks at the Superheat Pendant Outlet Header/Tube Nozzles resulting in repetitive forced plant shutdowns, TVA decided to replace the two Outlet Headers (one for each furnace) in Fall 2008 during a reliability outage. Since the entire Main Steam piping system was installed with cold pull at almost every longitudinal pipe segment, the main challenge from the engineering mechanics point of view was how to restrain the piping system especially at the Crossover Outlet Links inside each furnace Penthouse. Further constructability reviews indicated that there were not enough adjacent steel frames inside each furnace to restrain the four Crossover Outlet Links in the three global directions during the Outlet Headers replacement inside each Penthouse. The only existing steel above the Crossover Outlet Links is embedded in asbestos insulation, and the removal of the insulation to provide access for the temporary restraints was determined to be costly and time consuming. The insulation removal would have also caused the scheduled outage to be extended significantly and unrealistically. After careful assessment, technical evaluation, and several constructability reviews; it was decided to take an unconventional approach for relieving the inherent cold pull in three global directions by cutting the four Mixing Headers outside each furnace. In addition, the concept of installing several temporary restraints was utilized for the vertical and lateral directions inside the furnace Penthouse, as well as several others outside the Boiler to control the piping configuration of the four Mixing Headers. This approach achieved two purposes: 1- relieving the inherent cold pulls in three global directions and 2- controlling the four Outlet Links pipe end positions with respect to the new Superheat Pendant Outlet Header nozzles. This unconventional method used to relieve the piping cold pull from outside the Boilers, to control the Outlet Links movements inside the Boiler Penthouses, and to restrain the entire Main Steam piping system was successfully developed and implemented in the Fall 2008 reliability outage to replace the two Superheat Pendant Outlet Headers. This unconventional method is described in this paper.
Features and Benefits of Gamma Level and Density Measurement in the Power Industry
Authors: Riley Keith
Published: January 2011

This paper will address the application of Gamma Level and Density measurement in the Power Industry. The primary focus of our discussion will be on Coal/Biomass bins and mills. Both continuous and point level applications will be discussed as well as the basic principle behind Gamma technology.
Experimental Characterization of Two-Phase Flow Centrifugal Pumps
Authors: Campo Antonio , Chisely Eugene A.
Published: January 2011

In this experimental work, the pressure distribution was measured in a rotating, partially shrouded, open, radial impeller, inlet diffuser and volute under a wide range of air-water two-phase flow conditions. To obtain these pressure measurements, small-diameter pressure-tap holes were drilled through the casing of the radial pump. High speed photography was the vehicle to determine the flow regime of the air-water mixture through the vane and in the volute. An analytical model was developed to predict the radial pump single- and two-phase flow pressure distributions. The distribution for the latter was compared with the test data for different suction void fractions. The physical mechanism responsible for pump performance degradation was also investigated.
Developing Optimum Condenser Tube Life-Cycle Economics
Authors: Janikowski Daniel S.
Published: January 2011

A steam surface condenser can operate very reliably for many years. However, much of the tubing will spend a good portion of its life in a most demanding environment of high stresses, mechanical vibration, temperature variations causing thermal stresses, and exposure to corrosive chemicals and waters. Traditionally used copper alloys and lower performance 300 series stainless steel alloys may, at some point during the operating life of the plant, require replacement. The challenge for the plant operations staff is to understand the possible material failure mechanisms, and once they impact profitable performance, develop a long term cost analysis to determine the lowest cost replacement solution. This paper identifies the potential causes of condenser and heat exchanger tube failures and their alternative solutions, the impact of metal transport and provides tools to assign costs to help develop an economic justification for the replacement using a life-cycle analysis. In addition to the cost for treatment chemicals, the paper identifies the impact of forced outages and derates, reduction of generation, and other operation related costs, including the future potential of CO2 charges. Using HEI criteria, the thermal and mechanical performance of various tube materials are compared and used to build a model to justify the retube payback.
Combustion Turbine Fuel Flexibility From Plant Designer’s Perspective
Authors: Serbetci Walter I.
Published: January 2011

Industrial combustion turbines offer plant owners the flexibility of generating power typically either from natural gas or distillate oil # 2. This paper, from the power plant designer’s perspective, expands upon fuel variability and flexibility in combustion turbines based on the author’s past project experience. For various alternate fuels, issues such as additional fuel treatment requirements, fuel system design, ignition reliability, flame stability, emissions, impact on parts life and impact on power output are discussed. Initially, a generic combustion envelope is defined for gaseous fuels largely based on turbine manufacturers’ requirements. Then specific project experience addressing the fuel treatment systems and gas turbine modifications are presented for the following fuels: a) Medium Btu well-head gas, b) Vaporized LPG-natural gas mixture, c) Landfill gas, d) Syngas from gasification. Similarly, a generic combustion envelope is defined for liquid fuels and the specific requirements to burn the following alternate liquid fuels are discussed: a) Crude oil, b) Naphtha, c) Bio-diesel. Finally, due to its “green energy” potential, feasibility of burning coal bed methane (CBM) and coal mine ventilation air methane (VAM) in gas turbines is investigated.
The Considerations for Reviewing the Effects of Power Uprates, Including Repowering, on Existing Steam Surface Condensers
Authors: Nightingale Darren M.
Published: January 2011

Steam Surface Condensers are typically custom designed for each application based on specified design and expected performance criteria defined during the design phase of the power plant. Over the life of a plant, subsequent design improvements and performance enhancements in prime movers such as boilers, reactors, steam & gas turbines, etc. have enabled many plants to seriously consider a power uprate which would be in excess of the original design capabilities of the plant. However, power uprate evaluations, including repowering projects, often reveal that (given its fixed surface area nature) the Steam Surface Condenser is often a ‘limitation’ to any proposed power uprate or repowering heat balance.
Setting Up Pipe Hanger Survey Programs at New Power Plants
Authors: Kimball Lange , Mize Vernon
Published: January 2011

The ASME piping Code has long recognized the need to perform regular monitoring of pipe hangers at power plants. This is true not only of existing power plants but also of new power plants, including HRSGs and “conventional” steam generating plants. Pipe hanger condition is an external barometer of hidden problems with the piping and attached equipment. Recognizing pipe hanger distress can help prioritize pipe inspections and equipment maintenance. The first part of such a surveillance program is setting up the program. This should include: a.) defining the piping systems that will be monitored, b.) collecting survey documents, c.) setting up a schedule to perform the work, d.) training plant personnel who will be performing such a program and e.) obtaining a commitment by the plant/owners to maintain the program through the life of the plant. This paper discusses experiences and lessons learned setting up such programs at new “conventional” lignite and HRSG plants.
Biomass Attributes, Handling, and Processing Issues for Large Power Plants
Authors: Mahr Daniel
Published: January 2011

The power industry is confronting challenges with seemingly conflicting goals. Large, solid fuel power plants provide the reliability and flexibility utilities require for baseload, cycling, and on-demand situations. They provide the economy of scale needed to minimize the cost of production. Consumers/industry rely on affordable, dependable electrical energy. It’s an important part of our economy and our daily lifestyle. Reducing emission levels and conserving our finite resources are key components for achieving a sustainable environment.
Generator Fan Test Facility to Quantify Axial Flow Fan Aerodynamic Performance
Authors: Hunter A. I. C. , Scarton H. A. , Wilt K. R. , Salamah S. A. , Story D.
Published: January 2011

The General Electric fan test facility has been re-installed and commissioned in the Laboratory for Noise and Vibration Control Research, located on the second floor of the Jonsson Engineering Center (JEC 2110) in the Department of Mechanical, Aerospace and Nuclear Engineering at Rensselaer Polytechnic Institute, Troy NY. RPI provides a unique venue to have a fully dedicated facility with access to experts and graduate students specializing in different fields. A congruence of new interested RPI investigators, generator aerodynamic experts, the return of old collaborators, and the need to reduce cost and losses in generator components, conspired to re-commission an improved version of the original setup. The results presented show good correlation between CFD and measured performance.
Performance Testing of Combined Cycle Power Plant in Phased Construction
Authors: Jin Hugh , Sullivan Terrence B. , Friedman Jeffrey R.
Published: January 2011

Gas turbines in combined cycle (CC) power plants, in phased construction situations, usually operate for several months in the simple cycle (SC) mode while the steam portion of the plant is being constructed. At the time of commissioning the combined cycle phase, the gas turbines typically have accumulated a considerable number of operating hours and have possibly experienced some degradation, especially on turbines that have run on dual fuels. To determine the combined cycle new and clean performance, it is necessary to employ a phased testing approach. The phased testing approach involves testing the gas turbines when they are in new and clean condition and combining those results with the measured new and clean steam turbine cycle performance. The method of the phased testing has been introduced in ASME PTC 46 (1996) “Performance Test Code on Overall Plant Performance”. This paper will discuss in detail the test protocol, fundamental equations, corrections, and uncertainty analysis of phased testing. This paper will also discuss performance degradation and engine setting changes between the phases.
Study of Nitrogen Injection to Enhance Forced Convection for GFR Demonstrator ALLEGRO
Authors: Tauveron N. , Dor I. , Bentivoglio F.
Published: January 2011

In the frame of the international forum GenIV, the Gas Fast Reactor is considered as a promising concept, combining the benefits of fast spectrum and high temperature, using helium as coolant. In the Gas Fast Reactor development plan, ALLEGRO is the first necessary step towards the electricity generating prototype GFR. ALLEGRO is a low power Gas Cooled Fast Reactor studied in the European R&D framework. It is a loop type, non electricity generating reactor. In the current preliminary viability studies ALLEGRO safety system relies on centrifugal blowers in case of depressurised conditions. The present study concerns the use of blowers in case of nitrogen injection. It is a well-known fact that heavier gases (than helium) enhance natural circulation. The use of such gases (nitrogen is considered) can also enhance forced convection. A specific work on the impact of the use of alternative gas on blower behaviour is presented. Transient behaviours in depressurised situations are computed with the CATHARE2 code and analyzed. Applications to GFR concept are also described.
In-Situ Measurement of 3-Dimensional Fluid Flow and Temperature in a Geometrically Complex Duct for Characterization of Heavy-Duty Gas Turbine Inlet Air Compressor Bleed Heat Systems
Authors: Daigle Evan E. , Schmitt Thomas P.
Published: January 2011

As demands for increased operational flexibility are placed on heavy-duty gas turbines, the usage of inlet air compressor bleed heating devices has been expanded to increase the emissions-compliant operating envelope. To ensure that these devices maintain acceptable flow-field characteristics at the compressor face, a method to accurately determine the flow field characteristics at the compressor face is required. In the past, Computational Fluid Dynamics (CFD) analysis has been used to predict flow field characteristics at the compressor face. As a means by which to make a comparison between analytical predictions and empirically determined characteristics, a scale model direct measurement arrangement was devised and tested. Given the high flow speed and complex geometry in the vicinity of the compressor face, accurate in-situ measurement of the flow profile presents many challenges. The measurement arrangement must provide sufficient data density such that flow-field gradients are fully captured, while simultaneously maintaining a minimum level of obstruction attributable to the sensors. One of the end goals is to ensure that the measured flow is representative of the system in its final configuration. Measurement systems of sufficiently small size to minimally influence the flow, but of sufficiently high accuracy must be employed. Advances in the design and usage of a measurement system to empirically determine the flow field characteristics in the inlet air system of a heavy-duty industrial gas turbine are presented. This system was used to characterize a number of competing inlet air compressor bleed heating systems. The results of this characterization are compared qualitatively and quantitatively, with a specific focus on the technology of the measurement system and measurement techniques.
Use of CFD Modeling for Designing Intake and Discharge Structures in a Discharge Canal
Authors: Lin Fangbiao , Pigg George , Schohl Gerald
Published: January 2011

This paper presents a computational fluid dynamics (CFD) modeling approach for designing intake and discharge structures in a discharge canal for nuclear and fossil power plants. It discusses how the CFD models are developed, what types of results can be obtained from the CFD modeling study and how the results are used for developing designs of the intake and discharge structures. The pros and cons of the CFD modeling method for this type of application are also discussed. Intake and discharge structures for a “Helper Cooling Tower South” will be added to the discharge canal of the Crystal River Energy Complex (CREC). The CFD modeling was used to confirm suitable locations for the new intake and discharge structures to minimize potential recirculation and potential loss of cooling tower efficiency, and to evaluate the erosion of the banks on the north and south side of the canal due to the flow from the discharge structure. The CFD model was developed using FLUENT for the existing and future configurations of the discharge canal that consists of the existing intake, discharges, and the new intake and discharge structures. The CFD modeling runs were performed to investigate three-dimensional flow patterns, velocities and temperatures in the discharge canal under current and future operating conditions. Current and future conditions refer to those before and after installation of the Helper Cooling Tower South Intake and Discharge structures, respectively. Comparing the CFD results (streamlines, temperature and velocity distributions, etc.) for the future conditions to those for the existing conditions, the locations and designs of the new intake and discharge structures were assessed and developed. This study demonstrates that the new intake is not impacted by the new and existing discharge structures, and the existing intake will perform similarly as it performs before the construction of the new intake and discharges. The study also identifies some sections of the canal banks and bottom that may need to be protected from erosion due to the impacts of the high velocity water from the discharge structures.
Manage the Risk of Turbine Rotor Failure
Authors: Yates David , Tarantino Angelo , Kraijesteijn Joop
Published: January 2011

Turbine rotors failure has resulted in a broad spectrum of events ranging from catastrophic burst to prolonged forced outages that ultimately have significant economic costs for affected utilities. Avoiding turbine rotor failure and its associated cost requires a detailed understanding of the operational reliability of power generation equipment. Nearly all large body turbine and generator rotors manufactured in the United States typically have a central bore hole that provides suitable access from which to conduct various material inspections. The term “boresonics” has become synonymous with the procedure for performing ultrasonic examination of turbine rotor material as conducted from the surface of a central bore cavity. Boresonics is now a fairly common and accepted practice throughout the utility industry. In general, boresonics involves passing ultrasonic transducers through the rotor bore to search a given volume of material for flaws at different locations and orientations within a rotor forging. Each individual ultrasonic transducer has specific inherent performance characteristics based on known wave physics that governs the art of ultrasonic testing. The results of boresonic inspections offer utility engineers a basis for making intelligent decisions on the condition of turbine and generator rotors. This paper describes how boresonic inspections are typically performed in the industry. Furthermore, the paper will give a description of the equipment and required skills of the system operators and will present examples of findings based on KEMA’s experience in this field.
Numerical Study of the Flow and Temperature Distributions in a 350 MW Utility Boiler
Authors: Galindo-Garci´a Iva´n F. , Va´zquez Barraga´n Ana Karenina , Rossano Roma´n Miguel
Published: January 2011

A computational model is developed in order to analyze flow, temperature and species distributions inside a 350 MW utility boiler. It is assumed that identification of high temperature or high velocity zones will help in the prevention of failures in the boiler walls, superheaters, reheaters and economizers. For the analysis of these failures the modeling of the chemical and physical phenomena inside the boiler is important, because one of the known causes of tube failure is the non-uniform heating of the tubes, which strongly depends on the combustion gases flow and temperature distributions. The 3-D computational fluid dynamics (CFD) codes provide an effective tool for this type of calculations. CFD calculations were performed for the condition of 100% of total load for a 350 MW utility boiler using either pulverized coal or heavy oil as fuels. The CFD calculations adopt a 3D-formulation of the mean flow equations in combination with the standard high-Reynolds-number k-epsilon turbulence model and a probability density function to model fuel combustion. The tube banks are represented by a porous media model. Comparisons between calculations and key global parameters from the power plant show relatively good agreement. Velocity profiles show a very complex flow in the boiler, especially in the lower part of the boiler, where the injected streams form a cyclone at the center of the boiler.
Applying Acoustic Pulse Reflectometry in a Geothermal Energy Plant: A Case Study
Authors: Amir Noam , Bobrow Daniel , Pechter Tal
Published: January 2011

One major type of heat exchanger in geothermal power-plants acts to condense an organic vapor driving the generating turbines. Routine inspection carried out at such a plant in the spring of 2008 detected several leaking tubes in one of the condensers. The condenser consists of 11 banks, each with 284 tubes. The tubes in this condenser are 1″ in diameter and 18m in length. A sample of tubes was investigated by a metallurgical laboratory which determined that the failure mechanism was corrosion. This was eventually traced to a faulty maintenance procedure which left water traces after pressure hydro testing. Several NDT methods were considered in order to screen the tubes for leaks, so the unit could be brought up to standard performance levels. Eventually AcousticEye’s APR equipment was selected, based on the very short cycle time it offered, which could dramatically shorten plant downtime. After an initial feasibility test of one of the tube banks, the remaining 2840 tubes were inspected in 2 days. Four percent of the tubes were found either leaking or deteriorated above a predefined maximum acceptable damage level (pinholes and tube wall thickness reduction) and plugged. Benefits were prevention of a continued loss of 70 Kg/day of organic fluid (which is not only wasteful but also infringes on environmental legislation) and an increase of 1.5% in plant performance. Based on this experience, the operator decided to adopt APR based inspection as a standard procedure in its plants.