bluuebunny/crossref_metadata_2025 huggingface dataset:
A pilot examination of social context and everyday physical activity among adults receiving Community Mental Health Services
Authors: McCormick B. P. , Frey G. C. , Lee C.‐T. , Gajic T. , Stamatovic‐Gajic B. , Maksimovic M.
Published: January 2009

Objective:  Community mental health center (CMHC) clients include a variety of people with moderate to severe mental illnesses who also report a number of physical health problems. Physical activity (PA) has been identified as one intervention to improve health among this population; however, little is known about the role of social context in PA. The purpose of this study was to examine the role of social context in everyday PA among CMHC clients.

Method:  Data were collected from CMHC clients in two cultures using accelerometery and experience sampling methods. Data were analyzed using hierarchical linear modeling.

Results:  Independence in housing nor culture was significantly associated with levels of PA. Being alone was significantly negatively related to PA level.

Conclusion:  Social isolation appears to be negatively related to PA at the level of everyday life. Physical activity interventions with this population should consider including social components as a part of PA.
Cognition as predictor of current and follow‐up depressive symptoms in the general population
Authors: Simons C. J. P. , Jacobs N. , Derom C. , Thiery E. , Jolles J. , Van Os J. , Krabbendam L.
Published: January 2009

Objective:  Previous studies have reported an association between depression and poor cognitive functioning. Unknown is to what degree such associations are merely state‐related or reflect an enduring depression vulnerability. This study examined whether cognitive deficits predict current and/or follow‐up (sub)clinical depressive symptoms in the general population.

Method:  A population‐based sample of 569 female twins and 43 of their sisters completed a neuropsychological battery. Cross‐sectional and prospective associations between depressive symptoms measured at the subclinical [Symptom Checklist‐90 (SCL‐90)] and clinical level (Structured Clinical Interview for DSM‐IV disorders) and neuropsychological factors (episodic memory and information processing speed) were examined.

Results:  Structured Clinical Interview for DSM‐IV disorders baseline depressive symptoms were significantly associated with information processing speed but not with episodic memory. Episodic memory was significantly associated with follow‐up SCL‐90 depressive symptoms.

Conclusion:  Being depressed is accompanied by slower information processing. Poor memory functioning may be a predictor for the onset of subclinical depressive symptoms.
Effect of ultraviolet radiation on the expression of pp38MAPK and furin in human keratinocyte‐derived cell lines
Authors: Huynh Tien T. , Chan Kasey S. , Piva Terrence J.
Published: January 2009

Background: Ultraviolet radiation (UVR) is known to induce the activation of stress‐inflammation signal transduction pathways, and to induce the activity of many proteases in skin cells. It is unknown whether the activation of proteases such as furin is related to changes in the phosphorylation status of p38MAPK.

Methods: The effect of UVR on immortalized keratinocyte (HaCaT) and squamous cell carcinoma (Colo16) cells was investigated with respect to cell survival, phosphorylation of p38MAPK, and the proprotein convertase, furin. The cells were exposed to either a low or a high dose of UVA and/or UVB and the viability was monitored over 48 h, along with changes in the intracellular expression of p38MAPK and furin.

Results: Low‐dose UVA (2 kJ/m2) and/or UVB (0.2 kJ/m2) radiation had no effect on cell viability, except in UVA‐irradiated Colo16 cells. High UVA (20 kJ/m2) caused a loss of cell viability in HaCaT cells, but not in Colo16 cells. The opposite effect was seen in cells exposed to a high UVB dose (2 kJ/m2). The viability of both cell cultures decreased when exposed to high‐dose UVA+B radiation. UV irradiation downregulated the expression of phosphorylated p38 (pp38) in HaCaT cells irrespective of the UV dose and type. In Colo16 cells, UV radiation induced pp38 expression in the cells following exposure, with the highest increase in cells exposed to high‐dose UVA. The expression of furin in UV‐irradiated HaCaT cells was similar to that seen for pp38 expression. In Colo16 cells, UV radiation induced furin expression, with the highest increase seen in cells 24 h after exposure to both high‐dose UVB and UVA+B radiation.

Conclusion: The results show that there are differences between the effect of UV types and doses on cell function in the keratinocyte‐derived cell lines examined in this study. The level of furin expression in Colo16 cells correlated to changes in pp38 levels in the cells following exposure to UV radiation, but not in HaCaT cells. From an improved understanding of the signalling pathways and their downstream events and how these may differ as a result of tumorigenesis, it may enable the development of inhibitors, which may have therapeutic applications.
The development of a filter to enhance the efficacy and safety of excimer light (308 nm) therapy
Authors: Kobayashi Keiko , Yasuda Yoko , Shintani Yoichi , Sumitomo Taku , Saga Takashi , Kimura Makoto , Yamamoto Aya , Mori Toshio , Maeda Akira , Yamaguchi Yuji , Morita Akimichi
Published: January 2009

Background: Excimer light (308 nm) therapy is a new ultraviolet (UV) B phototherapy for which the efficacy and resulting DNA damage are not well established.

Purpose: To develop an effective and safe phototherapy using the excimer lamp, we studied the effects of different light cut‐off filters, A and B.

Methods: Efficacy was evaluated by measuring apoptosis using fluorescence‐activated cell sorting analysis. DNA damage was evaluated by measuring cyclobutane pyrimidine dimers (CPDs). Light sources, including normal wave and short wave (SW) excimer light, broad‐band (BB) UVB, and narrow‐band (NB) UVB, were examined using the filters. A human skin equivalent model was also examined.

Results: The ratio of positive apoptosis to CPD formation normalized to the mean induced by NB‐UVB was 5.7 using the excimer lamp without a filter, 6.3 using the excimer lamp with the A filter, 6.4 using the SW excimer lamp without a filter, and 4.2 using the BB‐UVB. The A filter reduced CPD formation induced by the normal wave and SW excimer lamp. In the human skin equivalent model, the use of filters significantly decreased the amount of CPD‐positive cells.

Conclusions: These findings suggest that using the A filter with the excimer lamp increases the efficacy and safety of excimer light therapy.
Feasibility and accuracy of a newly developed hand‐held device with a flat‐type fluorescent lamp for measuring the minimal erythema dose for narrow‐band UVB therapy
Authors: Morita Akimichi , Shintani Yoichi , Nishida Emi , Kato Hiroshi , Yoshida Hisashi , Minamoto Maki , Yamaguchi Yuji , Maeda Akira
Published: January 2009

Background: Narrow‐band ultraviolet B (NB‐UVB) for the treatment of refractory skin diseases, such as psoriasis and atopic dermatitis, requires an adequate irradiation protocol based on the minimal erythema dose (MED) to establish an optimal dosage schedule. Although MED can be measured using a systemic‐type irradiation unit, there are difficulties associated with this device. There is no standardized device available to determine the MED for NB‐UVB. Here, we compared a conventional device with a newly developed device for measuring MED.

Method: MED was measured in 16 psoriasis patients using both a conventional measuring device and the newly developed device, which comprised a hand‐held NB‐UVB (311–313 nm) flat‐type fluorescent lamp with neutral density filters having different transmittances ranging from 10% to 90%. This device was designed to be stably maintained on the skin surface and to provide a highly accurate measurement with only one UV irradiation exposure while also preventing UV radiation from leaking to nonirradiated areas.

Results: The MED values obtained from each patient were the same using both devices.

Conclusion: One‐time irradiation using the new hand‐held device with the NB‐UVB flat‐type fluorescent lamp is feasible and accurate for determining the MED to use in calculating the UV irradiation treatment dose.
Pathways involved in testicular germ cell apoptosis induced by H2O2in vitro
Authors: Maheshwari Ankur , Misro Man M. , Aggarwal Archana , Sharma Rajnesh K. , Nandan Deoki
Published: January 2009

H2O2 induces apoptosis in variety of cells; however, the sensitivities of testicular germ cells to H2O2 are not known. In the present study, H2O2, at concentrations in the range 1–10 μm, was found to induce apoptosis in testicular germ cells in vitro. Following 1 h of treatment with 10 μm H2O2, a 10‐fold rise in the percentage of apoptotic cells was observed. Induction of germ cell apoptosis was directly associated with a significant (P < 0.01) increase in lipid peroxidation and a concomitant decrease in superoxide dismutase and catalase activity. Examination of apoptotic signalling pathways revealed an increased expression of extrinsic (Fas, FasL and caspase‐8) and intrinsic (Bid, Bak, Bad, Bax and caspase‐9) markers, as well as p53, along with a simultaneous decrease in the Bcl‐2 protein at the highest concentration of H2O2 exposure. Both, c‐jun N‐terminal kinase and p38 phosphorylated forms were found to be up‐regulated. Interestingly, up‐regulation of the nuclear transcription factor kappa B was also observed. The respective transcripts for many of the above proteins followed an identical trend. Caspase‐3 activity was also estimated to be 30‐fold higher. Taken together, the above data indicate that testicular germ cells are prone to apoptosis at very low concentrations of H2O2, the mechanism of which involves extrinsic and intrinsic as well other regulatory pathways.
In Men with Erectile Dysfunction, Satisfaction with Quality of Erections Correlates with Erection Hardness, Treatment Satisfaction, and Emotional Well-Being
Authors: Kaminetsky Jed C. , Depko Andrzej J. , Ströberg Peter , Buvat Jacques , Tseng Li-Jung , Stecher Vera J.
Published: January 2009

Introduction

The validated Quality of Erection Questionnaire (QEQ) evaluates satisfaction with erection quality.

Aim

To collate QEQ data, including correlations between QEQ outcomes and outcomes assessing emotional well-being, treatment satisfaction, and erection hardness after sildenafil citrate treatment.

Methods

In four trials, men older than 18 years and with erectile dysfunction, a stable sexual partner, and no recent phosphodiesterase type 5 inhibitor use were randomized to double-blind flexible-dose sildenafil or placebo (1:1 ratio) for 6 or 10 weeks (two trials), fixed-dose 50 mg, 100 mg, and placebo (1:1:1 ratio) for 8 weeks (one trial), and 50 mg and 100 mg (1:1 ratio) for 4 weeks after 4 weeks of single-blind sildenafil 50 mg. Exclusion criteria included recent significant cardiovascular disease, use of nitrates, nitric oxide donors, cytochrome P450 3A4 inhibitors, or other erectile dysfunction treatment, and sildenafil hypersensitivity or previous severe or serious treatment-related adverse event.

Main Outcomes Measures

Scores on the QEQ, QEQ Question 5 (satisfaction with erection hardness), the Self-Esteem and Relationship Questionnaire, and the Erectile Dysfunction Inventory of Treatment Satisfaction; the percentage of occasions with Erection Hardness Score 3 (EHS 3, hard enough for penetration but not completely hard) and/or EHS 4 (completely hard and fully rigid); and Pearson correlation coefficients.

Results

1,296 men (18–80 years) were randomized. Except for the percentage of occasions with EHS 3, all outcomes improved in men treated with sildenafil and correlated positively with the change in QEQ scores in all trials.

Conclusions

Satisfaction with the quality of erections, which is easily monitored with the QEQ, correlated positively with measures of emotional well-being and treatment satisfaction and with the change in percentage of erections that were completely hard and fully rigid, but not with the change in percentage of erections that were hard enough for penetration but not completely hard.
ORIGINAL ARTICLE: Genomic sister‐disorders of neurodevelopment: an evolutionary approach
Authors: Crespi Bernard , Summers Kyle , Dorus Steve
Published: January 2009

Genomic sister‐disorders are defined here as diseases mediated by duplications versus deletions of the same region. Such disorders can provide unique information concerning the genomic underpinnings of human neurodevelopment because effects of diametric variation in gene copy number on cognitive and behavioral phenotypes can be inferred. We describe evidence from the literature on deletions versus duplications for the regions underlying the best‐known human neurogenetic sister‐disorders, including Williams syndrome, Velocardiofacial syndrome, and Smith–Magenis syndrome, as well as the X‐chromosomal conditions Klinefelter and Turner syndromes. These data suggest that diametric copy‐number alterations can, like diametric alterations to imprinted genes, generate contrasting phenotypes associated with autistic‐spectrum and psychotic‐spectrum conditions. Genomically based perturbations to the development of the human social brain are thus apparently mediated to a notable degree by effects of variation in gene copy number. We also conducted the first analyses of positive selection for genes in the regions affected by these disorders. We found evidence consistent with adaptive evolution of protein‐coding genes, or selective sweeps, for three of the four sets of sister‐syndromes analyzed. These studies of selection facilitate identification of candidate genes for the phenotypes observed and lend a novel evolutionary dimension to the analysis of human cognitive architecture and neurogenetic disorders.
Special Care Dentistry Association consensus statement on sedation, anesthesia, and alternative techniques for people with special needs
Authors: Glassman Paul , Caputo Anthony , Dougherty Nancy , Lyons Ray , Messieha Zakaria , Miller Christine , Peltier Bruce , Romer Maureen
Published: January 2009

Many people with special needs (PSN) have difficulty having good oral health or accessing oral health services because of a disability or medical condition. The number of people with these conditions living in community settings and needing oral health services is increasing dramatically due to advances in medical care, deinstitutionalization, and changing societal values. Many of these individuals require additional supports beyond local anesthesia in order to receive dental treatment services. The purpose of this consensus statement is to focus on the decision‐making process for choosing a method of treatment or a combination of methods for facilitating dental treatment for these individuals. These guidelines are intended to assist oral health professionals and other interested parties in planning and carrying out oral health treatment for PSN. Considerations for planning treatment and considerations for each of several alternative modalities are listed. Also discussed are considerations for the use of combinations of modalities and considerations for the repeated or frequent use of these modalities. Finally, the need to advocate for adequate education and reimbursement for the full range of support alternatives is addressed. The Special Care Dentistry Association (SCDA) is dedicated to improving oral health and well being of PSN. The SCDA hopes that these guidelines can help oral health professionals and other interested individuals and groups to work together to ensure that PSN can achieve a “lifetime of oral health.”
A review of guidelines for sedation, anesthesia,and alternative interventions for people with special needs
Authors: Glassman Paul
Published: January 2009

There are significant numbers of people in our society with disabilities or other special needs. Their number and percentage are growing, in some cases, dramatically. Many of these individuals need special support in order to receive dental treatment. Modalities that can be used to provide dental treatment include pharmacological approaches to produce various levels of sedation or anesthesia. In addition to the use of medications, there are also techniques that employ behavioral or psychological interventions. In some circumstances, physical support or protective stabilization is used. There are also social supports and prevention strategies that can impact the individual's preparation for and need for dental treatment.

This review of the numerous guidelines, which have been published for the use of sedation and anesthesia to facilitate the delivery of dental treatment, indicates that there are fewer guidelines for the inclusion of behavioral or psychological interventions or for the incorporation of social supports or prevention strategies. In addition, most published guidelines do not include considerations for people with special needs. There is a need for increased research and documentation of combined treatment modalities, and these combined approaches need to be incorporated into guidelines for patient care for people with special needs.

There is also a need to advocate for reimbursement systems that support all appropriate treatment options so that practitioners can be free to recommend treatment options based on the efficacy and safety of each option.
Providing deep sedation and general anesthesia for patients with special needs in the dental office‐based setting
Authors: Caputo Anthony Charles
Published: January 2009

This article discusses the issues of morbidity and mortality associated with deep sedation and general anesthesia specifically in the dental office‐based setting for patients with special needs (PSN). A focused review of a particular environment and patient population was challenging as it was difficult to identify articles that discuss the unique scope of this subject. During the review of the literature, no article was identified that discussed this exact topic. There were articles that discussed the delivery of general anesthesia for PSN in an outpatient setting and associated issues of morbidity and mortality. There were also articles and sources of information that discussed the delivery of general anesthesia for other patient populations in the office‐based setting. In an effort to support the scope of this article, some of these articles are discussed as they pertain to the subject of this article. In addition, an analysis of the author's practice over a 4‐year period is discussed in an effort to present relevant data per the scope of this article. After reviewing the literature and the author's clinical practice, it appears that the incidence of mortality for PSN in the dental office‐based setting is minimal and the incidence of morbidity for this same population is limited to relatively minor events. Ultimately, it was concluded that the delivery of general anesthesia for PSN in the dental office‐based setting can be considered a very safe and successful procedure.
Social supports and prevention strategies as adjuncts and alternatives to sedation and anesthesia for people with special needs
Authors: Glassman Paul , Miller Christine
Published: January 2009

People with special needs are assuming a more prominent place in our society. The number of people living in communities with medical, physical, and psychological conditions is increasing dramatically. In spite of the advances that people with special needs have made in recognition of their right to live in society and access services open to other people, their oral health is still significantly poorer than that of other groups.

There are a number of modalities that can complement or replace pharmacological interventions and allow individuals to have dental treatment in a dental office or clinic. These include behavioral or psychological interventions and social support and prevention strategies. Social supports include care management and integration of oral health services with general health and social service systems.

Preventive programs using modern “medical model” oral health prevention strategies also have the potential to reduce the burden of disease among people with special needs and therefore reduce the need for dental procedures. A social support system using community‐based Dental Hygienists acting as Dental Coordinators, is described along with outcomes demonstrating improved oral health for people with special needs living in community residential care facilities. Combined social support systems and community prevention strategies have the potential to reduce the need for pharmacological interventions in order to maintain oral health in populations of people with special needs. Social supports and modern preventive strategies must be included in the range of options available in communities in order to improve and maintain oral health for people with special needs.
Understanding basic behavioral support techniques as an alternative to sedation and anesthesia
Authors: Lyons Ray A.
Published: January 2009

Patients with special needs often present a challenge for the dental care team. The exacting and surgical nature of dental procedures requires significant patient cooperation to ensure the safe delivery of care. Some individuals who have special care needs have difficulty cooperating during treatment, thus creating a potentially harmful situation. Modern dentistry, particularly pediatric dentistry, provides the dental team with a variety of strategies designed to enable the team to safely provide comprehensive care in the least restrictive manner. These techniques range from tell‐show‐do, to medical stabilization, to general anesthesia. The effective use of noninvasive, nonpharmacologic behavioral guidance/support techniques cannot only avoid the need for sedation or general anesthesia, they can teach the patient to develop coping skills that may enable them to receive comprehensive care in a traditional dental setting over a lifetime. Unfortunately, many providers are inadequately trained in behavioral support strategies. This paper presents a review of noninvasive, nonpharmacologic behavioral support techniques with discussion regarding their application to persons with special care needs.
Psychological treatment of fearful and phobic special needs patients
Authors: Peltier Bruce
Published: January 2009

Dental fears and phobias trouble patients with and without special needs, and they are a problem for dentists, as well. This article reviews current research and literature related to methods used to alleviate dental fear and concludes that while some important psychological methods are available, much work is left to be done in this area. It is clear that there is an important role for psychological and behavioral input to the dentist–patient interaction. While dental phobia represents a class of special needs itself, patients with other important disabilities (e.g., physical or cognitive impairments) are sometimes comorbidly phobic, a condition often missed or misdiagnosed by treating practitioners. Office‐based techniques that focus on relaxation, breathing, imagery, hypnosis, and effective use of operatory language are described. The methods advocated here can be used with patients having mild or moderate cognitive impairments.

Readings are recommended for the dentist or auxiliary practitioner interested in learning these techniques.
Consent,restraint,and people with special needs:a review
Authors: Romer Maureen
Published: January 2009

Dentists providing treatment to individuals with developmental disabilities are often faced with unique medical/legal issues. Obtaining informed consent when a patient does not have capacity can be an involved process. Issues regarding therapeutic aides used for immobilization (i.e., restraint) during treatment may further complicate the situation. This area is controversial and has even resulted in legal difficulties for some dentists. Several topics related to the use of restraint are addressed in this article. A review of the literature and applicable laws pertaining to consent issues for people with special needs is presented and appropriate use of medical immobilization is discussed.

Existing guidelines are reviewed. Informed consent and the use of restraint should be incorporated into overall guidelines for the use of anesthesia, sedation, and alternative behavior management techniques in providing dental care to patients with special needs.
Effect of Pimobendan on Echocardiographic Values in Dogs with Asymptomatic Mitral Valve Disease
Authors: Ouellet M. , Bélanger M.C. , DiFruscia R. , Beauchamp G.
Published: January 2009

Background:Pimobendan (PIMO) is a novel inodilator that has shown promising results in the treatment of advanced mitral valve disease (MVD), but little is known about its hemodynamic effects, especially regarding the mitral regurgitant volume in naturally occurring MVD.

Hypothesis:The addition of pimobendan to treatment decreases the regurgitant fraction (RF) in dogs with asymptomatic MVD.

Animals:Twenty‐four client‐owned dogs affected by International Small Animal Cardiac Health Council class Ib MVD.

Methods:Prospective, blinded, and controlled clinical trial. Dogs were assigned to a PIMO treatment group (n = 19) (0.2–0.3 mg/kg q12h) or a control group (n = 5). Echocardiographic evaluations were performed over a 6‐month period.

Results:The addition of PIMO to treatment did not decrease the RF of dogs affected by asymptomatic class 1b MVD over the study period (P= .85). There was a significant increase in the ejection fraction of the PIMO treated dogs at 30 days (80.8 ± 1.42 versus 69.0 ± 2.76, correctedP= .0064), and a decrease in systolic left ventricular diameter (correctedP= .011) within the PIMO group compared with baseline. However, this improvement in systolic function was not sustained over the 6‐month trial period.

Conclusion and Clinical Importance:This study did not identify beneficial long‐term changes in the severity of mitral regurgitation after addition of PIMO to angiotensin converting enzyme inhibitor treatment of dogs with asymptomatic MVD.
Forced Response Prediction of Constrained and Unconstrained Structures Coupled Through Frictional Contacts
Authors: Cigeroglu Ender , An Ning , Menq Chia-Hsiang
Published: January 2009

In this paper, a forced response prediction method for the analysis of constrained and unconstrained structures coupled through frictional contacts is presented. This type of frictional contact problem arises in vibration damping of turbine blades, in which dampers and blades constitute the unconstrained and constrained structures, respectively. The model of the unconstrained/free structure includes six rigid body modes and several elastic modes, the number of which depends on the excitation frequency. In other words, the motion of the free structure is not artificially constrained. When modeling the contact surfaces between the constrained and free structure, discrete contact points along with contact stiffnesses are distributed on the friction interfaces. At each contact point, contact stiffness is determined and employed in order to take into account the effects of higher frequency modes that are omitted in the dynamic analysis. Depending on the normal force acting on the contact interfaces, quasistatic contact analysis is initially employed to determine the contact area as well as the initial preload or gap at each contact point due to the normal load. A friction model is employed to determine the three-dimensional nonlinear contact forces, and the relationship between the contact forces and the relative motion is utilized by the harmonic balance method. As the relative motion is expressed as a modal superposition, the unknown variables, and thus the resulting nonlinear algebraic equations in the harmonic balance method, are in proportion to the number of modes employed. Therefore the number of contact points used is irrelevant. The developed method is applied to a bladed-disk system with wedge dampers where the dampers constitute the unconstrained structure, and the effects of normal load on the rigid body motion of the damper are investigated. It is shown that the effect of rotational motion is significant, particularly for the in-phase vibration modes. Moreover, the effect of partial slip in the forced response analysis and the effect of the number of harmonics employed by the harmonic balance method are examined. Finally, the prediction for a test case is compared with the test data to verify the developed method.
Misalignment in Gas Foil Journal Bearings: An Experimental Study
Authors: Howard Samuel A.
Published: January 2009

As gas foil journal bearings become more prevalent in production machines, such as small gas turbine propulsion systems and microturbines, system level performance issues must be identified and quantified in order to provide for successful design practices. Several examples of system level design parameters that are not fully understood in foil bearing systems are thermal management schemes, alignment requirements, balance requirements, thrust load balancing, and others. In order to address some of these deficiencies and begin to develop guidelines, this paper presents a preliminary experimental investigation of the misalignment tolerance of gas foil journal bearing systems. Using a notional gas foil bearing supported rotor and a laser-based shaft alignment system, increasing levels of misalignment are imparted to the bearing supports while monitoring temperature at the bearing edges. The amount of misalignment that induces bearing failure is identified and compared with other conventional bearing types such as cylindrical roller bearings and angular contact ball bearings. Additionally, the dynamic response of the rotor indicates that the gas foil bearing force coefficients may be affected by misalignment.
Asymptotic Description of Maximum Mistuning Amplification of Bladed Disk Forced Response
Authors: Martel Carlos , Corral Roque
Published: January 2009

The problem of determining the maximum forced response vibration amplification that can be produced just by the addition of a small mistuning to a perfectly cyclical bladed disk still remains not completely clear. In this paper we apply a recently introduced perturbation methodology, the asymptotic mistuning model (AMM), to determine which are the key ingredients of this amplification process and to evaluate the maximum mistuning amplification factor that a given modal family with a particular distribution of tuned frequencies can exhibit. A more accurate upper bound for the maximum forced response amplification of a mistuned bladed disk is obtained from this description, and the results of the AMM are validated numerically using a simple mass-spring model.
Experimental Study on Impeller Blade Vibration During Resonance—Part I: Blade Vibration Due to Inlet Flow Distortion
Authors: Kammerer Albert , Abhari Reza S.
Published: January 2009

Forming the first part of a two-part paper, the experimental approach to acquire resonant vibration data is presented here. Part II deals with the estimation of damping. During the design process of turbomachinery components, mechanical integrity has to be guaranteed with respect to high cycle fatigue of blades subject to forced response or flutter. This requires the determination of stress levels within the blade, which in turn depend on the forcing function and damping. The vast majority of experimental research in this field has been performed on axial configurations for both compressors and turbines. This experimental study aims to gain insight into forced response vibration at resonance for a radial compressor. For this purpose, a research impeller was instrumented with dynamic strain gauges and operated under resonant conditions. Modal properties were analyzed using finite element method and verified using an optical method termed electronic-speckle-pattern-correlation-interferometry. During the experiment, unsteady forces acting on the blades were generated by grid installations upstream of the impeller, which created a distorted inlet flow pattern. The associated flow properties were measured using an aerodynamic probe. The resultant pressure fluctuations on the blade surface and the corresponding frequency content were assessed using unsteady computational fluid dynamics. The response of the blades was measured for three resonant crossings, which could be distinguished by the excitation order and the natural frequency of the blades. Measurements were undertaken for a number of inlet pressure settings starting at near vacuum and then increasing. The overall results showed that the installed distortion screens generated harmonics in addition to the fundamental frequency. The resonant response of the first and the second blade mode showed that the underlying dynamics support a single-degree-of-freedom model.
Experimental Study on Impeller Blade Vibration During Resonance—Part II: Blade Damping
Authors: Kammerer Albert , Abhari Reza S.
Published: January 2009

Forming the second part of a two-part paper, the estimation of damping is presented here. Part I discusses the experimental approach and the results on blade resonant response measurements. In the study of forced response, damping is a crucial parameter, which is measured to quantify the ability of a vibrating system to dissipate vibratory energy in response to a given excitation source. The blading of turbomachinery components is particularly prone to forced response excitation, which is one of the major causes of high cycle fatigue failure during operation. In turbocharging applications, forced response cannot be avoided due to a number of factors, i.e., change in speed, inlet bends, or obstructions in the flow field. This study aims to quantify the damping parameter for the lightly damped blades of a centrifugal compressor. The impeller geometry is typical of turbocharging applications. As a first step, the nonrotating impeller was excited using piezos, and the transfer function was derived for a number of pressure settings. Both circle-fit and curve-fit procedures were used to derive material damping. In the second step, measurements were taken in the test facility where forced response conditions were generated using distortion screens upstream of the impeller. The main blade strain response was measured by sweeping through a number of resonant points. A curve-fit procedure was applied to estimate the critical damping ratio. The contributions of material and aerodynamic dampings were derived from a linear curve-fit applied to the damping data as a function of inlet pressure. Overall, it will be shown that aerodynamic damping dominates the dissipation process for applications with an inlet pressure of 1 bar. Damping was found to depend on the throttle setting of the compressor, and where applicable computational fluid dynamics results were used to point toward the possible causes of this effect.
Flow Field and Combustion Characterization of Premixed Gas Turbine Flames by Planar Laser Techniques
Authors: Stopper Ulrich , Aigner Manfred , Meier Wolfgang , Sadanandan Rajesh , Stöhr Michael , Kim Ik Soo
Published: January 2009

Lean premixed natural gas/air flames produced by an industrial gas turbine burner were analyzed using laser diagnostic methods. For this purpose, the burner was equipped with an optical combustion chamber and operated with preheated air at various thermal powers P, equivalence ratios Φ, and pressures up to p=6 bars. For the visualization of the flame emissions OH∗ chemiluminescence imaging was applied. Absolute flow velocities were measured using particle image velocimetry (PIV), and the reaction zones as well as regions of burnt gas were characterized by planar laser-induced fluorescence (PLIF) of OH. Using these techniques, the combustion behavior was characterized in detail. The mean flow field could be divided into different regimes: the inflow, a central and an outer recirculation zone, and the outgoing exhaust flow. Single-shot PIV images demonstrated that the instantaneous flow field was composed of small and medium sized vortices, mainly located along the shear layers. The chemiluminescence images reflected the regions of heat release. From the PLIF images it was seen that the primary reactions are located in the shear layers between the inflow and the recirculation zones and that the appearance of the reaction zones changed with flame parameters.
A Simple Mathematical Approach to Data Reconciliation in a Single-Shaft Combined Cycle System
Authors: Gülen S. Can , Smith Raub W.
Published: January 2009

The ultimate proof of the soundness and viability of a novel technology is a full-scale demonstration test in which actual components are run successfully over the entire operating envelope. Consequently, the collection of accurate and meaningful test data is of utmost importance to the success of the test. An analysis of such data will validate the original design concepts and will lead to paths of further improvement for the next generations thereof. Statistical fundamentals to determine the accuracy and precision of measured data are amply documented and readily available in well-established standards. The yardstick that should be used for the “meaningfulness” of the measured test data is the satisfaction of the fundamental laws of conservation. While it is known that the “true” values of the sensor data when inserted into the governing equations for the tested component will result in perfect balances, “actual” measured values will always result in “imbalances.” Therefore, reconciliation of the individual measurements with the governing conservation equations is a must prior to the actual analysis of the data. Reconciliation in this context is an estimation of the true values of the sensor data from the actual sensor data by using statistical concepts. This paper describes the development of a data reconciliation concept that is universally applicable to any process or power plant system where sensor data are used. The usefulness and power of the technique are demonstrated by its application to a single-shaft combined cycle with both gas turbine and steam turbine driving a common generator. In the absence of a reliable and accurate measuring system to individually determine gas and steam turbine shaft outputs, data reconciliation is vital to an accurate analysis of the data.
Effect of Time and Temperature on Thermal Barrier Coating Failure Mode Under Oxidizing Environment
Authors: Cheruvu N. S. , Chan K. S. , Gandy D. W.
Published: January 2009

Thermal barrier coatings (TBCs) have been recently introduced to hot section components, such as transition pieces and the first two stages of turbine blades and vanes of advanced F, G, and H class land-based turbine engines. The TBC is typically applied on metallic-coated components. The metallic bond coat provides oxidation and/or corrosion protection. It is generally believed that the primary failure mode of TBCs is delamination and fracture of the top ceramic coating parallel to the bond coat in the proximity of the thermally grown oxide (TGO) between coatings. One of the concerns associated with the use of a TBC as a prime reliant coating is its long-term stability. The effect of long-term operation at typical land based turbine operating temperatures of below 1010°C (1850°F) of the failure mode of TBCs is unknown. Long-term isothermal tests were conducted on the thermal barrier-coated specimens at three temperatures, 1010°C (1850°F), 1038°C (1900°F), and 1066°C (1950°F), to determine the effects of long term exposure on the TBC failure location (mode). Following the isothermal testing, the samples were destructively examined to characterize the degradation of the TBC and determine the extent of TGO cracking, TGO growth, bond coat oxidation, and TBC failure location after long term exposure for up to 18,000h. Optical microscopy and a scanning electron microscope (SEM) attached with an energy dispersive spectroscopy (EDS) system were used to study the degradation of the TBC and bond coatings. The results showed that long term isothermal exposure leads to a change in the TBC failure mode from the delamination of the TBC at the TGO∕TBC interface to the internal oxidation of the bond coat and bond coat delamination. In this paper, the effect of long-term exposure on the delamination of TBC and the bond coat failure mode is discussed.
Performance and Cost Analysis of Advanced Gas Turbine Cycles With Precombustion CO2 Capture
Authors: Hoffmann Stéphanie , Bartlett Michael , Finkenrath Matthias , Evulet Andrei , Ursin Tord Peter
Published: January 2009

This paper presents the results of an evaluation of advanced combined cycle gas turbine plants with precombustion capture of CO2 from natural gas. In particular, the designs are carried out with the objectives of high efficiency, low capital cost, and low emissions of carbon dioxide to the atmosphere. The novel cycles introduced in this paper are comprised of a high-pressure syngas generation island, in which an air-blown partial oxidation reformer is used to generate syngas from natural gas, and a power island, in which a CO2-lean syngas is burnt in a large frame machine. In order to reduce the efficiency penalty of natural gas reforming, a significant effort is spent evaluating and optimizing alternatives to recover the heat released during the process. CO2 is removed from the shifted syngas using either CO2 absorbing solvents or a CO2 membrane. CO2 separation membranes, in particular, have the potential for considerable cost or energy savings compared with conventional solvent-based separation and benefit from the high-pressure level of the syngas generation island. A feasibility analysis and a cycle performance evaluation are carried out for large frame gas turbines such as the 9FB. Both short-term and long-term solutions have been investigated. An analysis of the cost of CO2 avoided is presented, including an evaluation of the cost of modifying the combined cycle due to CO2 separation. The paper describes a power plant reaching the performance targets of 50% net cycle efficiency and 80% CO2 capture, as well as the cost target of 30$ per ton of CO2 avoided (2006 Q1 basis). This paper indicates a development path to this power plant that minimizes technical risks by incremental implementation of new technology.
On the Use of Actively Controlled Auxiliary Bearings in Magnetic Bearing Systems
Authors: Cade Iain S. , Sahinkaya M. Necip , Burrows Clifford R. , Keogh Patrick S.
Published: January 2009

Auxiliary bearings are used to prevent rotor/stator contact in active magnetic bearing systems. They are sacrificial components providing a physical limit on the rotor displacement. During rotor/auxiliary bearing contact significant forces normal to the contact zone may occur. Furthermore, rotor slip and rub can lead to localized frictional heating. Linear control strategies may also become ineffective or induce instability due to changes in rotordynamic characteristics during contact periods. This work considers the concept of using actively controlled auxiliary bearings in magnetic bearing systems. Auxiliary bearing controller design is focused on attenuating bearing vibration resulting from contact and reducing the contact forces. Controller optimization is based on the H∞ norm with appropriate weighting functions applied to the error and control signals. The controller is assessed using a simulated rotor/magnetic bearing system. Comparison of the performance of an actively controlled auxiliary bearing is made with that of a resiliently mounted auxiliary bearing. Rotor drop tests, repeated contact tests, and sudden rotor unbalance resulting in trapped contact modes are considered.
Ultrahigh-frequency microplasma jet as a low-power, high-density, and localized ions/radicals source
Authors: Miyazoe Hiroyuki , Sai Masaki , Stauss Sven , Terashima Kazuo
Published: January 2009

An ultrahigh-frequency (450 MHz) microplasma jet was stably generated at a chamber pressure as low as 10−3 Pa. Electron and gas temperatures of this microplasma as estimated by optical-emission spectroscopy measurements were ∼7000 and 1000 K, respectively. The atomic oxygen flux at the torch exit was revealed to be of the order of 1019 atoms/cm2 s, which is 102–104 times higher than that obtained by other conventional plasma sources. This microplasma jet was also applied as an ion source for in situ neutralization of electron charging-up effects in a scanning-electron microscopy observation of insulating materials.
Numerical study of the sputtering in a dc magnetron
Authors: Kolev Ivan , Bogaerts Annemie
Published: January 2009

In this article, the process of sputtering and the behaviour of the sputtered atoms in a dc magnetron is studied by means of numerical simulations. The proposed model is a self-consistent approach, based on the particle-in-cell-Monte Carlo collision method. In this way, the process of sputtering is treated self-consistently with respect to the other processes in the magnetron plasma. The studied pressure range is 1–100mtorr. The effects of the target-substrate distance and the choice of the scattering angle in the collisions between sputtered atoms and background gas atoms are also discussed.
Growth and characterization of TiAlN∕CrAlN superlattices prepared by reactive direct current magnetron sputtering
Authors: Barshilia Harish C. , Deepthi B. , Rajam K. S. , Bhatti Kanwal Preet , Chaudhary Sujeet
Published: January 2009

TiAlN and CrAlN coatings were prepared using a reactive direct current magnetron sputtering system from TiAl and CrAl targets. Structural characterization of the coatings using x-ray diffraction (XRD) revealed the B1 NaCl structure of TiAlN and CrAlN coatings with a prominent reflection along the (111) plane. The XPS data confirmed the bonding structures of TiAlN and CrAlN single layer coatings. Subsequently, nanolayered multilayer coatings of TiAlN∕CrAlN were deposited on silicon and mild steel (MS) substrates at different modulation wavelengths (Λ) with a total thickness of approximately 1.0μm. The modulation wavelengths were calculated from the x-ray reflectivity data using modified Bragg’s law. TiAlN∕CrAlN multilayer coatings were textured along (111) for Λ<200Å and the XRD patterns showed the formation of superlattice structure for coatings deposited at Λ=102Å. The x-ray reflectivity data showed reflections of fifth and seventh orders for multilayer coatings deposited at Λ=102 and 138Å, respectively, indicating the formation of sharp interfaces between TiAlN and CrAlN layers. The cross-sectional scanning electron microscopy image of TiAlN∕CrAlN multilayer coatings indicated a noncolumnar and dense microstructure. A maximum hardness of 39GPa was observed for TiAlN∕CrAlN multilayer coatings deposited at Λ=93Å, which was higher than the rule-of-mixture value (30GPa) for TiAlN and CrAlN. Study of thermal stability of the coatings in air using micro-Raman spectroscopy indicated that the TiAlN∕CrAlN multilayer coatings were stable up to 900°C in air. TiAlN∕CrAlN multilayer coatings also exhibited improved corrosion resistance when compared to the MS substrate.
Plasma atomic layer etching using conventional plasma equipment
Authors: Agarwal Ankur , Kushner Mark J.
Published: January 2009

The decrease in feature sizes in microelectronics fabrication will soon require plasma etching processes having atomic layer resolution. The basis of plasma atomic layer etching (PALE) is forming a layer of passivation that allows the underlying substrate material to be etched with lower activation energy than in the absence of the passivation. The subsequent removal of the passivation with carefully tailored activation energy then removes a single layer of the underlying material. If these goals are met, the process is self-limiting. A challenge of PALE is the high cost of specialized equipment and slow processing speed. In this work, results from a computational investigation of PALE will be discussed with the goal of demonstrating the potential of using conventional plasma etching equipment having acceptable processing speeds. Results will be discussed using inductively coupled and magnetically enhanced capacitively coupled plasmas in which nonsinusoidal waveforms are used to regulate ion energies to optimize the passivation and etch steps. This strategy may also enable the use of a single gas mixture, as opposed to changing gas mixtures between steps.