bluuebunny/crossref_metadata_2025 huggingface dataset:
Testosterone Increases Blood Flow and Expression of Androgen and Estrogen Receptors in the Rat Vagina
Authors: Traish Abdulmaged M. , Kim Soo Woong , Stankovic Miljan , Goldstein Irwin , Kim Noel N.
Published: May 2007

Introduction

The mechanisms by which testosterone modulates female genital sexual arousal responses are poorly understood.

Aim

To investigate the effects of testosterone on vaginal blood flow and the expression of estrogen and androgen receptor proteins in the rat vagina.

Methods

Mature female Sprague-Dawley rats were sham-operated (intact) or ovariectomized. Fourteen days after ovariectomy, animals were continuously infused with vehicle or varying doses of testosterone (5.5–55 μg/day). After 2 weeks of treatment, vaginal blood flow in response to pelvic nerve stimulation was measured by laser Doppler flowmetry. Plasma levels of testosterone and estradiol were determined by radioimmunoassay and epithelial thickness was examined in fixed vaginal tissue sections. Androgen and estrogen receptor levels were assessed by equilibrium radioligand binding and by Western blot analyses.

Results

Vaginal blood flow responses were significantly reduced in ovariectomized rats and normalized in animals infused with testosterone. Ovariectomy increased the expression of estrogen receptors and reduced the expression of androgen receptors with no change in receptor-ligand affinity. Testosterone increased the expression of both androgen and estrogen receptors in the vagina. While physiological (11 μg/day) and supraphysiological (55 μg/day) concentrations of testosterone normalized vaginal tissue weight, uterine tissue and whole body weights were not significantly different from ovariectomized rats infused with vehicle. Testosterone infusion, even at supraphysiological concentrations, did not change plasma estradiol levels when compared to vehicle-infused, ovariectomized rats. Likewise, the vaginal epithelium of testosterone-infused rats remained atrophic, similar to vehicle-infused, ovariectomized rats, indicating that testosterone is not aromatized to estrogens at significant levels in the vagina.

Conclusion

Our data suggest that testosterone regulates androgen and estrogen receptor protein expression in the vagina and enhances vaginal perfusion by an androgen-dependent mechanism. We conclude that testosterone plays an important role in modulating the physiology of the vagina and contributes to improvement of genital sexual arousal responses.
Micropropagation through excised root culture of Clitoria ternatea and comparison between in vitro–regenerated plants and seedlings
Authors: Shahzad A. , Faisal M. , Anis M.
Published: May 2007

An efficient protocol has been developed for high‐frequency shoot regeneration and plant establishment of Clitoria ternatea – a potential medicinal legume. Adventitious shoots were regenerated from young excised root segments of aseptic seedlings on Murashige and Skoog (MS) medium supplemented with various concentrations of 6‐benzyladenine (BA), kinetin, α‐naphthalene acetic acid (NAA) or 2,4‐dichlorophenoxy acetic acid (2,4‐D) either singly or in various combinations. The highest frequency (100%) of shoot regeneration and maximum number (16.4 ± 0.24) of shoots per explant was obtained on MS medium supplemented with 20 μm BA and 2.0 μm NAA. Organogenic calli were produced on a medium containing 2,4‐D (10 or 20 μm) and BA (5.0 μm). The calli were differentiated into multiple shoots on MS medium supplemented with 2.5–10 μm BA and 2.0 μm NAA. The microshoots were rooted on half‐strength MS medium supplemented with 5.0 μm indole‐3‐butyric acid and transplanted successfully in field conditions. After 12 months of transfer to ex vitro conditions, the performance of micropropagated plants were evaluated on the basis of some physiological and biochemical parameters and compared with the in vivo–grown plants of the same age. The sodium dodecyl sulphate polyacrylamide gel electrophoresis protein profile was same between regenerated and naturally growing shoots. Total soluble protein in aerial part as well as in seeds of in vitro–regenerated and in vivo–grown plants was almost the same. The mitotic study showed normal chromosomal movement and numbers (2x = 16).
Holey Aroids: Circular Trenching Behavior by a Leaf Beetle in Vietnam
Authors: Darling D. Christopher
Published: May 2007

The leaf beetle Aplosonyx ancora cuts circular trenches on the underside of leaves of their aroid host plants before feeding. Latex is exuded from these cuts and the beetles feed intermittently on these isolated tissues, apparently avoiding the latex. Circular feeding holes occur only in Araceae in which latex is contained in cells or vessels with cells bridging adjacent files (“anastomosing laticifers”). The phylogeny of Araceae and the restricted host records suggest a coevolutionary arms race and parallel phylogenesis between Aplosonyx and its aroid hosts.
Efficacy of Granulocyte and Monocyte Adsorption Apheresis for Three Cases of Refractory Pyoderma Gangrenosum
Authors: Seishima Mariko , Mizutani Yoko , Shibuya Yoshinao , Nagasawa Chikako , Aoki Takahiko
Published: May 2007

Abstract:  Pyoderma gangrenosum presents with chronic skin ulcers and is histologically characterized by neutrophil infiltration throughout the dermis. It is also occasionally associated with ulcerative colitis, a type of inflammatory bowel disease, against which granulocyte and monocyte adsorption apheresis (GCAP) has recently shown remarkable efficacy. We performed GCAP on three refractory cases of pyoderma gangrenosum with painful bilateral leg ulcers and hereby report the results obtained. Patient 1 was a 43‐year‐old woman with a four‐year history of recurrent painful skin ulcers treated with prednisolone and cyclosporine. Patient 2 was a 29‐year‐old woman who had been suffering from pyoderma gangrenosum with severe pain for two weeks, associated with an 11‐year history of ulcerative colitis treated with prednisolone and salazosulfapyridine. Patient 3 was a 63‐year‐old man with a three‐year history of recurrent ulcers with pain, suffering from rheumatoid arthritis treated with prednisolone and cyclophosphamide. The sizes of the lesions were reduced in all three patients following a weekly GCAP treatment for 10 or 11 consecutive weeks, and the re‐epithelialization of ulcers were additionally observed in two patients. The pain disappeared dramatically in all three patients following two sessions of GCAP therapy. No adverse effects were observed for up to at least eight months after treatment. We therefore considered GCAP as one effective alternative to currently existing therapies, with regards to refractory cases of pyoderma gangrenosum.
Darbepoetin Alfa Effectively Maintains Hemoglobin Concentrations at Extended Dose Intervals Relative to Intravenous rHuEPO in Japanese Dialysis Patients
Authors: Akizawa Tadao , Koshikawa Shozo , Iwasaki Manabu ,   KRN321 A08 Study Group
Published: May 2007

Abstract:  Darbepoetin alfa (KRN321) is a novel molecule that stimulates erythropoiesis by the same mechanism as endogenous erythropoietin. Due to its three‐fold longer half‐life and greater biological activity than recombinant human erythropoietin (rHuEPO), KRN321 maintains an effective hemoglobin (Hb) level at extended dose intervals compared with rHuEPO. In this multicenter, open‐label study, 513 dialysis patients maintained on stable rHuEPO therapy were switched to KRN321 at extended dose intervals. Those receiving rHuEPO two (n = 144, 28.1%) or three times (n = 305, 59.5%) per week were switched to KRN321 once per week, and those receiving rHuEPO once per week (n = 64, 12.5%) were switched to KRN321 once every two weeks. The doses of KRN321 (10–120 μg) were titrated to maintain Hb concentrations at 10–13 g/dL and, if possible, within 11–12 g/dL for up to 52 weeks. If the Hb concentration remained between 10.5 and 12 g/dL, conversion of the dosing frequency from once per week to once every two weeks was allowed. Hemoglobin concentrations were maintained regardless of the dosing interval. The percentage of patients with Hb values within 11–12 g/dL was 23.6% at week 0, 41.3% at week 7, 46.1%−51.9% between weeks 11 and 22 and 45.6% at week 52. KRN321 was well tolerated and the safety profile was consistent with previous trials conducted for KRN321. KRN321, when administered at extended dose intervals, is well tolerated and effective Hb concentrations are attained in Japanese hemodialysis patients.
Iron Status and the Use of Non‐Steroidal Anti‐Inflammatory Drugs in Hemodialysis Patients
Authors: Wang Xiaoxia , Uzu Takashi , Isshiki Keiji , Kanasaki Masami , Hirata Kunio , Soumura Mariko , Nakazawa Jun , Kashiwagi Atsunori , Takaya Kiho , Isono Motohide , Nishimura Masataka , Shikano Tsutomu , Nishio Toshiji , Tomita Kobin , Arimura Tetsuro ,   Lake Biwa Clinical Dialysis Meeting
Published: May 2007

Abstract:  We examined whether the use of non‐steroidal anti‐inflammatory drugs (NSAIDs) can affect the anemia and iron status of hemodialysis patients. We recruited patients from six dialysis centers who had undergone maintenance hemodialysis for at least four months. We examined the use of NSAIDs during the past three months based on their medical records and assigned the patients to three groups (group A, non‐NSAID group; group B, aspirin group; and group C, non‐aspirin NSAID group). Of the 446 patients, 95 (21.3%) were treated with aspirin and 103 (23.1%) were treated with non‐aspirin NSAIDs. The serum iron level and transferrin saturation (TSAT) were significantly lower in group C patients than those in group A. However, the ratio of the patients who were administrated iron preparations during the past three months was significantly higher than that in the other two groups. The incidences of positive fecal occult blood tests did not differ substantially between the three groups. The ratios of the patients who were administrated recombinant human erythropoietin were the same between three groups. Using a multiple regression analysis, the administration of non‐aspirin NSAIDs was identified as an independent factor for the decreased serum iron and the decreased TSAT levels. A multiple logistic regression analysis revealed that the patients using non‐aspirin NSAIDs had an increased the requirement for iron preparation therapy (OR 2.03, 95% CI, 1.28‐3.22). The use of non‐aspirin NSAIDs may therefore increase the risk of the iron deficiency in patients undergoing hemodialysis.
L and T dwarfs in the Hyades and Ursa Major moving groups
Authors: Bannister N. P. , Jameson R. F.
Published: May 2007

We have used the moving cluster method to identify three L dwarfs and one T dwarf in the Ursa Major/Sirius moving group (age 400 Myr). Five L dwarfs and two T dwarfs are found to belong to the Hyades moving group (age 625 Myr). These L and T dwarfs define 400- and 625-Myr empirical isochrones, assuming that they have the same age. Moving group membership does not guarantee coevality.
Defining and Evaluating Models of Cognition Used in Educational Measurement to Make Inferences About Examinees' Thinking Processes
Authors: Leighton Jacqueline P. , Gierl Mark J.
Published: May 2007

The purpose of this paper is to define and evaluate the categories of cognitive models underlying at least three types of educational tests. We argue that while all educational tests may be based—explicitly or implicitly—on a cognitive model, the categories of cognitive models underlying tests often range in their development and in the psychological evidence gathered to support their value. For researchers and practitioners, awareness of different cognitive models may facilitate the evaluation of educational measures for the purpose of generating diagnostic inferences, especially about examinees' thinking processes, including misconceptions, strengths, and/or abilities. We think a discussion of the types of cognitive models underlying educational measures is useful not only for taxonomic ends, but also for becoming increasingly aware of evidentiary claims in educational assessment and for promoting the explicit identification of cognitive models in test development. We begin our discussion by defining the term cognitive model in educational measurement. Next, we review and evaluate three categories of cognitive models that have been identified for educational testing purposes using examples from the literature. Finally, we highlight the practical implications of “blending” models for the purpose of improving educational measures.
The Science and Practice of Environmental Flows and the Role of Hydrogeologists
Authors: Sophocleous Marios
Published: May 2007

Conflicts between ecosystems and human needs for fresh water are increasing. The purpose of this paper is to raise awareness in the hydrogeologic community of environmental flows (EFs) and to address the major challenges involved in their protection. Ground water is a key component of EFs, and therefore hydrogeologists are called upon to get involved in the ongoing debates about maintaining healthy riverine ecosystems. Promising opportunities for achieving EFs in both underallocated and overallocated basins as well as new methods for protecting fresh water ecosystems developed in different countries are outlined. EF protection measures include private water trusts, “upside‐down instream flow water rights,” the “public trust” doctrine, and water markets, among other measures. A number of knowledge gaps are identified, to which hydrogeologists could contribute, such as our rudimentary knowledge about ground water–dependent ecosystems, aspects of stream‐aquifer interactions, and the impacts of land‐use changes. The values that society places on the different uses of water ultimately determine where the water is allocated. EF requirements can be legitimately recognized and addressed by basing the environmental needs of hydrologic systems on robust science, focusing on increasing the productivity of water use, engaging society in understanding the benefits and costs of decisions that affect ecosystems, and taking advantage of various opportunities for achieving EF goals.
Heterogeneity and Thermal Modeling of Ground Water
Authors: Ferguson Grant
Published: May 2007

Heat transport in aquifers is becoming an increasingly important topic due to recent growth in the use of ground water in thermal applications. However, the effect of heterogeneity on heat transport in aquifers has yet to be examined in the same detail as it has been for solute transport, and it is unclear what effect this may have on our ability to create accurate models. This study examines this issue through stochastic modeling using the geostatistics for two aquifers with low and high degrees of heterogeneity. The results indicate that there is considerable uncertainty in the distribution of heat associated with injection of warm water into an aquifer. Heterogeneity in the permeability field was also found to slightly reduce the ability to recover this introduced heat at a later time. These simulations also reveal that hydrodynamic macrodispersion is an important consideration in some heat flow problems.
Using patient‐centered interviewing skills to manage complex patient encounters in primary care
Authors: Lein Catherine , Wills Celia E.
Published: May 2007

Purpose: To describe effective and efficient patient‐centered interviewing strategies to enhance the management of complex primary care patient encounters.

Data sources: Research literature and applied case study analysis.

Conclusions: Patient‐centered interviewing can enhance effectiveness of care in complex patient encounters. A relatively small investment of time and energy has positive yields in regard to improvements in longer term physiological status, treatment adherence, quality of life, patient–provider working relationship, and patient and nurse practitioner satisfaction.

Implications for practice: Use of patient‐centered interviewing strategies can enhance effectiveness of patient care processes and outcomes while retaining efficiency of patient management.
Promoting self‐care through symptom management: A theory‐based approach for nurse practitioners
Authors: Fowler Christopher , Kirschner Michelle , Van Kuiken Debra , Baas Linda
Published: May 2007

Purpose: To present a theory of illness representation useful in clinical practice along with two case studies as examples of theory implementation.

Data sources: Literature review of relevant theory and associated literature, case studies from clinical practice.

Conclusions: An individual asks several questions when experiencing a physical sensation: “Am I sick, stressed, or is this a sign of aging? If I’m sick, is the symptom connected with a disease label?” After asking these questions, the individual develops a cognitive and emotional illness representation that includes the dimensions of identity, cause, consequences, control, and timeline. This representation is guided by personal, cultural, and environmental contexts and determines coping strategies. By assessing the individual’s cognitive and emotional representations of the illness, the nurse practitioner (NP) can use the common sense model of illness representation (CSM) to establish interventions and action plans helpful in decreasing distress in the management of symptoms.

Implications for practice: NPs frequently care for patients who present with very severe symptoms related to their health problem. This becomes a major challenge in effective disease management. Leventhal’s CSM can be used as a framework to identify the cognitive and emotional illness representations individuals develop when acute and chronic symptoms are presented. By assessing the individual’s cognitive and emotional representations of the illness, the NP will be able to use the CSM to establish interventions and action plans that will be helpful in decreasing the patient’s distress in the management of symptoms.
Use of bioelectrical impedance analysis in the evaluation, treatment, and prevention of overweight and obesity
Authors: Ricciardi Richard , Talbot Laura A
Published: May 2007

Purpose: To present an overview of bioelectrical impedance analysis (BIA) and to familiarize nurse practitioners (NPs) with the potential benefits of using BIA in prevention, monitoring, and long‐term follow‐up of healthy individuals and those with chronic conditions (e.g., obesity).

Data sources: Original research articles and comprehensive review articles identified through Medline, CINAHL, OVID, and electrical engineering databases.

Conclusions: Obtaining serial measurements of percent body fat using BIA can identify patients at greatest health risk and gives NPs an additional tool to assess treatment response in patients seeking to lose or maintain body weight and/or increase muscle mass.

Implications for practice: Traditionally, height/weight tables and body mass index have been used to assess body composition and diagnose overweight and obesity. More recently, BIA has emerged as a portable and simple‐to‐operate instrument to evaluate body composition in the clinical setting.
Impact of academic nurse‐managed centers on communities served
Authors: Pohl Joanne M. , Barkauskas Violet H. , Benkert Ramona , Breer Lynn , Bostrom Andrea
Published: May 2007

Purpose: This paper presents findings from six community focus groups that addressed the impact of academic nurse‐managed centers (ANMCs) on the overall community being served as well as the quality of care provided in the centers.

Data sources: Experts in focus group methodology from a public health institute conducted the six focus groups at ANMCs from four universities in the Midwest. Discussions were guided by nine questions presented to each group. All groups were tape‐recorded and transcribed. A total of 37 participants were recruited from the ANMCs and included patients and families, advisory board members, and local community organizations.

Conclusions: Four themes were identified across the six focus groups: valuing patient‐centered care, which included two subthemes—continuous specific provider and specific aspects of care; quality of care; increasing access to care/addressing the safety net; and evidence of outreach.

Implications for practice: Findings from these focus groups verify that community members do “get it” in terms of the unique aspects of ANMCs. Participants were able to articulate the differences between nurse‐managed care and other types of ambulatory primary care. The unique strengths of nurse practitioners were repeatedly articulated as well as the centers’ outreach into the community.
Inactivation of Shigella boydii 18 IDPH and Listeria monocytogenes Scott A with Power Ultrasound at Different Acoustic Energy Densities and Temperatures
Authors: Ugarte‐Romero Edgar , Feng Hao , Martin Scott E.
Published: May 2007

ABSTRACT:  The effect of acoustic energy density (AED) on inactivation of Shigella boydii 18 IDPH and Listeria monocytogenes Scott A in a cell suspension was studied at sublethal temperatures and at AEDs of 0.49, 0.85, and 1.43 W/mL. The effect of temperature on ultrasonic inactivation of L. monocytogenes Scott A at 35, 50, and 65 °C was examined at an AED of 1.43 W/mL. Increasing AED increased the rate of inactivation for both S. boydii and L. monocytogenes. The destruction of S. boydii and L. monocytogenes followed 1st order kinetics in a 20‐min treatment, except for S. boydii inactivation at 1.43 W/mL where a tailing effect was observed after 15 min. At sublethal temperatures, the D‐values of S. boydii were 8.8, 4.3, and 2.5 min for AEDs of 0.49, 0.85, and 1.43 W/mL, whereas those for L. monocytogenes at the 3 AED levels were 31.5, 13.5, and 7.3 min, respectively. Ultrasonic treatment of L. monocytogenes at 35 and 50 °C enhanced inactivation. However, at 65 °C, application of ultrasound did not result in additional inactivation compared to thermal treatment alone at the same temperature. With the experimental conditions and the ultrasound system used in this study, an upper temperature limit for thermosonication was evident above which no added killing due to ultrasound was observed.
Quality Changes in Beef Gluteus Medius, Infraspinatus, Psoas Major, Rectus Femoris, and Teres Major Enhanced Prior to Aging
Authors: Stetzer A.J. , Tucker E. , McKeith F.K. , Brewer M.S.
Published: May 2007

ABSTRACT:  The objective of this study was to evaluate the effects of enhancement and aging on quality characteristics of the gluteus medius (round), rectus femoris (round), teres major (chuck), infraspinatus (chuck), and psoas major (loin). Muscles were enhanced, vacuum packaged, and aged for 7 or 14 d. Aging affected enhanced compared with nonenhanced beef differently. After 7 d of aging, enhanced beef experienced more cook loss and was less red (higher hue angle, lower a* values, and chroma) than did nonenhanced beef; after 14 d of aging, these differences were lost. Enhancement increased tenderness and brown color of the gluteus medius (round); however, it decreased visual green and red colors. Enhanced gluteus medius experienced 3.1% lower purge losses, lower L* values, and chroma than their nonenhanced counterparts. Enhancement increased infraspinatus (chuck) tenderness and visual brown color, and decreased visual red and green colors, purge loss, L* value, a* value, and chroma. The enhanced infraspinatus was substantially more tender than the other muscles evaluated, other than the gluteus medius; however, it was also substantially more visually brown. Enhancement decreased purge loss of the psoas major. Enhancement increased L* and a* values, hue angles, and chroma than other enhanced muscles. After enhancement the tenderness of the rectus femoris increased by 10%, decreased purge losses from 4.5% to 1.7%, and decreased green color by 18%. It reduced L* and a* values and chroma. Aging increased tenderness. Overall, muscles from the chuck (infraspinatus and teres major) appeared to benefit the most from enhancement.
The Study of β‐Lactoglobulin Adsorption on Polyethersulfone Thin Film Surface Using QCM‐D and AFM
Authors: Kim J.T. , Weber N. , Shin G.H. , Huang Q. , Liu S.X.
Published: May 2007

ABSTRACT:  The adsorption process of β‐lactoglobulin on the polyethersulfone‐coated surface has been investigated using a quartz crystal microbalance with dissipation monitoring (QCM‐D), which allowed simultaneous measurements of frequency and energy dissipation changes caused by the formation of a β‐lactoglobulin layer during the protein adsorption process. The results showed that the protein adsorption on the spin‐coated polyethersulfone surface consisted of reversible and irreversible adsorption processes, and the irreversible adsorption was the principal factor to cause the permanent protein adsorption onto the polymer surface. The amount of irreversible adsorption of β‐lactoglobulin increased significantly, from 380.5 ± 23.2 to 745.5 ± 29.7 ng/cm2, when the concentration of β‐lactoglobulin solution varied from 0.1% to 2.0% (w/v). The pH also played an important role in the protein adsorption. When the pH of the solution varied from 7.0 to 3.0, the amount of irreversible adsorption of β‐lactoglobulin increased from 427.1 ± 80.7 to 741.2 ± 135.1 ng/cm2.
Design Process Sequencing With Competent Genetic Algorithms
Authors: Meier Christoph , Yassine Ali A. , Browning Tyson R.
Published: May 2007

In product design, it is critical to perform project activities in an appropriate sequence. Otherwise, essential information will not be available when it is needed, and activities that depend on it will proceed using assumptions instead. Later, when the real information is finally available, comparing it with the assumptions made often precipitates a cascade of rework, and thus cost and schedule overruns for the project. Information flow models have been used to sequence the engineering design process to minimize feedback and iteration, i.e., to maximize the availability of real information where assumptions might otherwise be made instead. In this paper, we apply Genetic Algorithms (GAs) to an information flow model to find an optimized sequence for a set of design activities. The optimality of a solution depends on the objective of rearrangement. In an activity sequencing context, objectives vary: reducing iteration/feedback, increasing concurrency, reducing development lead-time and cost, or some combination of these. We adopt a matrix-based representation scheme, the design structure matrix (DSM), for the information flow models. Our tests indicate that certain DSM characteristics (e.g., size, sparseness, and sequencing objective) cause serious problems for simple Genetic Algorithm (SGA) designs. To cope with the SGA deficiency, we investigate the use of a competent GA: the ordering messy GA (OmeGA). Tests confirm the superiority of the OmeGA over a SGA for hard DSM problems. Extensions enhancing the efficiency of both a SGA and the OmeGA, in particular, niching and hybridization with a local search method, are also investigated.
Type Synthesis of Parallel Mechanisms With Multiple Operation Modes
Authors: Kong Xianwen , Gosselin Clément M. , Richard Pierre-Luc
Published: May 2007

There are usually several motion patterns having the same degrees of freedom (DOF). For example, planar motion, spherical motion, and spatial translation are motion patterns with 3 DOF. An f-DOF parallel mechanism with multiple operation modes is a parallel mechanism that can generate different motion patterns with f DOF. Up to now, no method has been proposed for the type synthesis of parallel mechanisms with multiple operation modes. This paper presents a general method for the type synthesis of parallel mechanisms with multiple operation modes. Using the proposed approach, 3-DOF parallel mechanisms with both spherical and translational modes, i.e., parallel mechanism generating both a spherical motion pattern and a spatial translational motion pattern, are generated systematically. A large number of parallel mechanisms with both spherical and translational modes are obtained.
Kinematic Investigation of the Deployable Bennett Loop
Authors: Eddie Baker J.
Published: May 2007

Despite the many studies devoted to it and its value as a learning tool, the Bennett linkage has never been employed as a working mechanism. It has recently found favor, however, among structural analysts as a possible unit in deployable networks owing to the potential for true spatial displacement without flexure. Although the loop can be analyzed in this application by means of purely geometrical methods, a wealth of kinematic examinations is available for more efficient treatment. The particular form that the chain must adopt as a deployable object and the special case of the linkage demanded by the purpose constitute the subject of the present exposition, which takes full advantage of prior analyses of the chain’s kinematic characteristics.
Characteristics of Beam-Based Flexure Modules
Authors: Awtar Shorya , Slocum Alexander H. , Sevincer Edip
Published: May 2007

The beam flexure is an important constraint element in flexure mechanism design. Nonlinearities arising from the force equilibrium conditions in a beam significantly affect its properties as a constraint element. Consequently, beam-based flexure mechanisms suffer from performance tradeoffs in terms of motion range, accuracy and stiffness, while benefiting from elastic averaging. This paper presents simple yet accurate approximations that capture the effects of load-stiffening and elastokinematic nonlinearities in beams. A general analytical framework is developed that enables a designer to parametrically predict the performance characteristics such as mobility, over-constraint, stiffness variation, and error motions, of beam-based flexure mechanisms without resorting to tedious numerical or computational methods. To illustrate their effectiveness, these approximations and analysis approach are used in deriving the force–displacement relationships of several important beam-based flexure constraint modules, and the results are validated using finite element analysis. Effects of variations in shape and geometry are also analytically quantified.
Study on Hydraulic Energy-Recovering Workover Rig and the Simulation for Lifting the Pipestring
Authors: Lujun Zhang
Published: May 2007

In this paper, an advanced energy-saving petroleum machinery, the hydraulic energy-recovering workover rig, is researched. The equipped power of this rig is only one third of an ordinary rig, and this rig can also recover and reuse the potential energy which is released by the pipestring when lowered. The special working theory of this rig is introduced. An energy-saving analysis is conducted. Analysis shows that when lowering the pipestring which weighs 260kN, the energy recovered by this rig is about 240×106J. The mathematical model of lifting the pipestring is established and a simulation analysis is conducted. Through simulation, some conclusions are obtained: (1) the lighter the pipestring the shorter the pipestring lifting time; (2) the smaller the throttle valve path area the longer the pipestring lifting time; (3) the smaller the air vessel volume the shorter the pipestring lifting time. The actual measurement results prove that the simulation results are right.
Performance Evaluation of a Gas Turbine Operating Noncontinuously with its Inlet Air Cooled Through an Aquifer Thermal Energy Storage
Authors: Behafarid Farhad , Bahadori Mehdi N.
Published: May 2007

The power output of gas turbines (GT) reduces greatly with the increase of the inlet air temperature. This is a serious problem because gas turbines have been used traditionally to provide electricity during the peak power demands, and the peak power demands in many areas occur on summer afternoons. An aquifer thermal energy storage (ATES) was employed for cooling of the inlet air of the GT. Water from a confined aquifer was cooled in winter and was injected back into the aquifer. The stored chilled water was withdrawn in summer to cool the GT inlet air. The heated water was then injected back into the aquifer. A 20MW GT power plant with 6 and 12h of operation per day, along with a two-well aquifer, was considered for analysis. The purpose of this investigation was to estimate the GT performance improvement. The conventional inlet air cooling methods such as evaporative cooling, fogging and absorption refrigeration were studied and compared with the ATES system. It was shown that for 6h of operation per day, the power output and efficiency of the GT on the warmest day of the year could be increased from 16.5 to 19.7MW and from 31.8% to 34.2%, respectively. The performance of the ATES system was the best among the cooling methods considered on the warmest day of the year. The use of ATES is a viable option for the increase of gas turbines power output and efficiency, provided that suitable confined aquifers are available at their sites. Air cooling in ATES is not dependent on the wet-bulb temperature and therefore can be used in humid areas. This system can also be used in combined cycle power plants.
Performance Analysis and Optimization of Double-Flash Geothermal Power Plants
Authors: Dagdas Ahmet
Published: May 2007

One of the most important cycles for electricity generation from geothermal energy is the double-flash cycle. Approximately 25% of the total geothermal based electricity generation all over the world comes from double-flash geothermal power plants. In this paper, performance analysis of a hypothetical double-flash geothermal power plant is performed and variations of fundamental characteristics of the plant are examined. In the performance analysis, initially, optimum flashing pressures are determined, and energy and exergy values of the base points of the plant are calculated. In addition, first and second law efficiencies of the power plant are calculated. Main exergy destruction locations are determined and these losses are illustrated in an exergy flow diagram. For these purposes, it is assumed that a hypothetical double-flash geothermal power plant is constructed in the conditions of western Turkey. The geothermal field where the power plant will be built produces geofluid at a temperature of 210°C and a mass flow rate of 200kg∕s. According to simulation results, it is possible to produce 11,488kWe electrical power output in this field. Optimum first and second flashing pressures are determined to be 530kPa and 95kPa, respectively. Based on the exergy of the geothermal fluid at reservoir, overall first and second law efficiencies of the power plant are also calculated to be 6.88% and 28.55%, respectively.
Effect of Fuel Properties on the Bottom Ash Generation Rate by a Laboratory Fluidized Bed Combustor
Authors: Rozelle Peter L. , Pisupati Sarma V. , Scaroni Alan W.
Published: May 2007

The fluidized bed combustion (FBC) process, used in power generation, can handle a variety of fuels. However, the range of fuels that can be accommodated by an FBC boiler system is affected by the ability of the fuel, sorbent, and ash-handling equipment to move the required solids through the boiler. Of specific interest is the bottom ash handling equipment, which must have sufficient capacity to remove ash from the system in order to maintain a constant bed inventory level, and must have sufficient capability to cool the ash well below the bed temperature. Quantification of a fuel’s bottom ash removal requirements can be useful for plant design. The effect of fuel properties, on the rate of bottom ash production in a laboratory FBC test system was examined. The work used coal products ranging in ash content from 20to40+wt.%. The system’s classification of solids by particle size into flyash and bottom ash was characterized using a partition curve. Fuel sizing was compared to the partition curve, and fuels were fractionated by particle size. Fuel fractions in the size range characteristic of bottom ash were further analyzed for distributions of ash content with respect to specific gravity, using float sink tests. The fuel fractions were then ashed in a fixed bed. In each case, the highest ash content fraction produced ash with the coarsest size consist (characteristic of bottom ash). The lower ash content fractions were found to produce ash in the size range characteristic of flyash, suggesting that the high ash content fractions were largely responsible for the production of bottom ash. The contributions of the specific gravity fractions to the composite ash in the fuels were quantified. The fuels were fired in the laboratory test system. Fuels with higher amounts of high specific gravity particles, in the size ranges characteristic of bottom ash, were found to produce more bottom ash, indicating the potential utility of float sink methods in the prediction of bottom ash removal requirements.
SURFACE STRUCTURES ON CLEAVED SILICON BY CLEAVAGE LUMINESCENCE DETECTION
Authors: LI DONGGUANG
Published: May 2007

This paper reports on further research into the structure and properties of the cleaved surfaces of silicon, using vacuum cleavage luminescence detection methods.

Results show resistance partially recovers during the cleavage process through "crack healing". When the elasticity of the parts transmitting the applied stress temporarily absorbs the initial rupture stress, the crack stops and partially re-closes until the applied force "catches up" and reapplies stress. The high resistance created by the two Schottky barriers prevents resistance recovery from mere surfaces re-contact. Instead, resistance recovery from the atom-to-atom re-closure surface healing is more likely, as expected from a Three Bond Scission Model (TBS) silicon surface structure.
SURFACE BEHAVIOR OF BIOACTIVE GLASS OF Si–Na–Ca–P SYSTEM IN SIMULATED BODY FLUID
Authors: MA JIE , CHEN CHUANZHONG , WANG DIANGANG , DANG XING , BAO RUILIANG , YAO LIANG
Published: May 2007

Glass of the Si – Na – Ca – P system has been synthesized by normal melting and annealing technique. The obtained glass powders and annealed blocks were showed to be amorphous by X-ray diffraction (XRD). The thermal properties of glasses were analyzed by differential scanning calorimetry (DSC), it showed that the glass transformation temperature (Tg) was 556.3°C. The behavior of annealed glass discs in simulated body fluid solution (SBF) was studied in polyethylene containers at a constant temperature of 37°C for different time up to 14 days. The changes in the surface morphology and composition were observed by electronic probe microanalyzer (EPMA) associated with energy dispersive spectroscopy (EDS). Glass surface changed quickly as soon as immersion took place, and after longer soaking time, it showed different superimposed internal and external layers, which were identified as SiO 2-rich and CaO – P 2 O 5-rich layers, and on the external layer, spherical particles were also discovered.
ENHANCED CALCIUM PHOSPHATE PRECIPITATION ON THE SURFACE OF Mg-ION-IMPLANTED ZrO2 BIOCERAMIC
Authors: LIANG H. , HUANG Y. , HE F. , DING H. F. , WAN Y. Z.
Published: May 2007

Modification of bioceramics by ion implantation of magnesium ( Mg ) is of interest as Mg is the fourth abundant cation in the human body. In this work, magnesium was ion-implanted into a ZrO 2 based bioceramic stabilized with Y 2 O 3 and Al 2 O 3. Both Mg -implanted and unimplanted samples were soaked in a simulated body fluid (SBF) for a period of time. The deposits on the surface of various samples were characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). We find that the Mg -implanted ZrO 2 shows better bioactivity than the plain bioceramic. These results indicate that Mg -implantation can improve the bioactivity of the ZrO 2 based bioceramic. Mechanisms governing the improvement are discussed in this paper.
THE ELECTROCHEMICAL STUDY OF SELF-ASSEMBLED 1,3-PROPANEDITHIOL ON GOLD
Authors: MIAO YUQING , CHEN JIANRONG , WU XIAOHUA , FANG KEMING
Published: May 2007

The electrochemical behaviors of bare/dithiol-modified gold electrode were studied in the PBS solution with/without dithiols. A pair of current peaks between -1.4 and -0.5 V is related to dithiol adsorption or re-adsorption. An oxidative peak at 0.37 V accompanied by a slight peak at 0.03 V is observed between -0.5 and 0.7 V for the bare gold electrode in the thiol solution, which is due to the formation of bilayer. When the potential is scanned to a very positive value at 1.2 V, a new oxidative peak at 1.07 V appears for the bare gold electrode in the dithiol solution or the PBS solution. The assembled dithiols are desorbed, and gold surface is exposed. The study indicates that the 1,3-propanedithiol modified electrodes should be used during the potential range of -0.8 to 0.8 V to keep the assembled layer stable.
STRUCTURAL CHARACTERISTICS OF (Ba,Sr)TiO3 THIN FILMS BY RAPID THERMAL ANNEALING
Authors: ZHANG Q. Y. , JIANG S. W. , LI Y. R.
Published: May 2007

The rapid thermal annealing (RTA) process was adapted to crystallize the amorphous ( Ba,Sr ) TiO 3 thin films prepared on Si (111) substrates by RF magnetic sputtering deposition. The effect of annealing temperature, heating rate and duration time on crystallization was studied through X-ray diffraction and atomic force microscopy. The result shows that the crystallinity and grain size were strongly dependent on the temperature, heating rate, and duration time. Higher heating rate leads to smaller grain size. In high heating rate, the grain size shows different dependence of temperature from that of low heating rate. For a heating rate of 50°C/s, the grain size decreased with temperature increasing below 700°C, while after that temperature, the grain size increased slightly with the temperature increasing. At a certain temperature, the crystallinity and surface roughness improved with increase in annealing time, while grain size changed little. The effect of rapid heating rate on the nucleation and grain growth has been discussed, which contributes to the limited grain size of the annealed ( Ba,Sr ) TiO 3 thin films.
EFFECT OF ACETYLENE FLOW RATE ON ELECTROSORPTION CAPACITY OF CARBON NANOTUBE AND NANOFIBER COMPOSITE FILM ELECTRODES
Authors: WANG X. Z. , PAN L. K. , LI M. G. , CHEN Y. W. , CHENG R. M. , HUANG S. M. , SUN Z.
Published: May 2007

Electrosorption of carbon nanotube and nanofiber (CNT–CNF) composite film electrodes was studied as a new desalination technology. The CNT–CNF composite film electrodes were grown on nickel sheets by low pressure thermal chemical vapor deposition. Different growth conditions at different acetylene flow rates of CNT–CNF composite film electrodes have been performed to obtain different crystallinities. The electrosorption experiments and Raman spectra analysis show the successful removal of ions with CNT–CNF composite film electrodes, depending on the optimal degree of crystalline perfection. In our work, optimal electrosorption was realized for the CNT–CNF composite film electrodes growing at 550°C with the acetylene and hydrogen flow rates of 30 and 200 sccm.
Muscle Na+-K+-ATPase response during 16 h of heavy intermittent cycle exercise
Authors: Green H. J. , Duhamel T. A. , Holloway G. P. , Moule J. W. , Ouyang J. , Ranney D. , Tupling A. R.
Published: May 2007

This study investigated the effects of a 16-h protocol of heavy intermittent exercise on the intrinsic activity and protein and isoform content of skeletal muscle Na+-K+-ATPase. The protocol consisted of 6 min of exercise performed once per hour at ∼91% peak aerobic power (V̇o2 peak) with tissue sampling from vastus lateralis before (B) and immediately after repetitions 1 (R1), 2 (R2), 9 (R9), and 16 (R16). Eleven untrained volunteers with a V̇o2 peakof 44.3 ± 2.3 ml·kg−1·min−1participated in the study. Maximal Na+-K+-ATPase activity ( Vmax, in nmol·mg protein−1·h−1) as measured by the 3- O-methylfluorescein K+-stimulated phosphatase assay was reduced ( P < 0.05) by ∼15% with exercise regardless of the number of repetitions performed. In addition, Vmaxat R9 and R16 was lower ( P < 0.05) than at R1 and R2. Vanadate-facilitated [3H]ouabain determination of Na+-K+-ATPase content (maximum binding capacity, pmol/g wet wt), although unaltered by exercise, increased ( P < 0.05) 8.3% by R9 with no further increase observed at R16. Assessment of relative changes in isoform abundance measured at B as determined by quantitative immunoblotting showed a 26% increase ( P < 0.05) in the α2-isoform by R2 and a 29% increase in α3by R9. At R16, β3was lower ( P < 0.05) than at R2 and R9. No changes were observed in α1, β1, or β2. It is concluded that repeated sessions of heavy exercise, although resulting in increases in the α2- and α3-isoforms and decreases in β3-isoform, also result in depression in maximal catalytic activity.
Enhanced adiponectin multimer ratio and skeletal muscle adiponectin receptor expression following exercise training and diet in older insulin-resistant adults
Authors: O'Leary Valerie B. , Jorett Ashley E. , Marchetti Christine M. , Gonzalez Frank , Phillips Susan A. , Ciaraldi Theodore P. , Kirwan John P.
Published: May 2007

Circulating adiponectin is reduced in disorders associated with insulin resistance. This study was conducted to determine whether an exercise/diet intervention would alter adiponectin multimer distribution and adiponectin receptor expression in skeletal muscle. Impaired glucose-tolerant older (>60 yr) obese (BMI 30–40 kg/m2) men ( n = 7) and women ( n = 14) were randomly assigned to 12 wk of supervised aerobic exercise combined with either a hypocaloric (ExHypo, ∼500 kcal reduction, n = 11) or eucaloric diet (ExEu, n = 10). Insulin sensitivity was determined by the euglycemic (5.0 mM) hyperinsulinemic (40 mU·m−2·min−1) clamp. Adiponectin multimers [high (HMW), middle (MMW), and low molecular weight (LMW)] were measured by nondenaturing Western blot analysis. Relative quantification of adiponectin receptor expression through RT-PCR was determined from skeletal muscle biopsy samples. Greater weight loss occurred in ExHypo compared with ExEu subjects (8.0 ± 0.6 vs. 3.2 ± 0.6%, P < 0.0001). Insulin sensitivity improved postintervention in both groups (ExHypo: 2.5 ± 0.3 vs. 4.4 ± 0.5 mg·kg FFM−1·min−1, and ExEu: 2.9 ± 0.4 vs. 4.1 ± 0.4 mg·kg FFM−1·min−1, P < 0.0001). Comparison of multimer isoforms revealed a decreased percentage in MMW relative to HMW and LMW ( P < 0.03). The adiponectin SA ratio (HMW/total) was increased following both interventions ( P < 0.05) and correlated with the percent change in insulin sensitivity ( P < 0.03). Postintervention adiponectin receptor mRNA expression was also significantly increased (AdipoR1 P < 0.03, AdipoR2 P < 0.02). These data suggest that part of the improvement in insulin sensitivity following exercise and diet may be due to changes in the adiponectin oligomeric distribution and enhanced membrane receptor expression.
Temporal Limitations in Object Processing Across the Human Ventral Visual Pathway
Authors: McKeeff Thomas J. , Remus David A. , Tong Frank
Published: May 2007

Behavioral studies have shown that object recognition becomes severely impaired at fast presentation rates, indicating a limitation in temporal processing capacity. Here, we studied whether this behavioral limit in object recognition reflects limitations in the temporal processing capacity of early visual areas tuned to basic features or high-level areas tuned to complex objects. We used functional MRI (fMRI) to measure the temporal processing capacity of multiple areas along the ventral visual pathway progressing from the primary visual cortex (V1) to high-level object-selective regions, specifically the fusiform face area (FFA) and parahippocampal place area (PPA). Subjects viewed successive images of faces or houses at presentation rates varying from 2.3 to 37.5 items/s while performing an object discrimination task. Measures of the temporal frequency response profile of each visual area revealed a systematic decline in peak tuning across the visual hierarchy. Areas V1–V3 showed peak activity at rapid presentation rates of 18–25 items/s, area V4v peaked at intermediate rates (9 items/s), and the FFA and PPA peaked at the slowest temporal rates (4–5 items/s). Our results reveal a progressive loss in the temporal processing capacity of the human visual system as information is transferred from early visual areas to higher areas. These data suggest that temporal limitations in object recognition likely result from the limited processing capacity of high-level object-selective areas rather than that of earlier stages of visual processing.