bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuing Medical Education: Regulation of Epididymal Contractility During Semen Emission, the First Part of the Ejaculatory Process: A Role for Estrogen (CME)
Authors: Vignozzi Linda , Filippi Sandra , Morelli Annamaria , Luconi Michaela , Jannini Emmanuele , Forti Gianni , Maggi Mario
Published: October 2008

Introduction

Ejaculation is an important step of the male sexual response, and consists of three separate phases: emission, ejection, and orgasm. In contrast to the erectile process, whose neurological and vascular mechanisms have been well elucidated, the pathophysiology of the ejaculatory process remains yet to be completely investigated. In humans, the emission and the ejection phases are regulated by an integrated and time-coordinated activity of the parasympathetic and sympathetic systems, which finally leads to sperm propulsion from the urethra. The first step in the ejaculatory process involves the epididymis, where a series of contractile waves begins, allowing sperm progression throughout the duct and toward the vas deferens.

Interestingly, along with the complex neurological pathways, some non-neuronal factors (oxytocin [OT] and endothelin-1 [ET-1]) and sex hormones (estrogen) have been demonstrated to take part in the peripheral regulation of epididymal contractility.

Aim

This article reviews some of the physiological non-neuronal mechanisms underlying the epididymal contractility, and reports evidences of an estrogenic regulation.

Methods

We reviewed here our and other groups' publications on the role of ET-1/OT and estrogens in modulating the epididymal contractility.

Main Outcome Measure

Data were obtained by an extensive examination of the published peer-reviewed literature on this topic.

Results

Evidences support that, although the epididymis has a rich innervation, other local, non-neuronal factors participate in the nerve-independent epididymal contractility. ET-1 and OT, along with their cognate receptors, have been demonstrated to act, in an estrogen-dependent autocrine and paracrine loop, to regulate epididymal contractile activity in rabbit, and at least partially, in humans.

Conclusion

Ejaculation is the result of the complex, and today still not fully elucidated, interplay between neuronal and non-neuronal, sex-steroid-dependent factors.
ORIGINAL RESEARCH—BASIC SCIENCE: The Associations among GNB3 C825T Polymorphism, Erectile Dysfunction, and Related Risk Factors
Authors: Lee Yung-Chin , Lin Hui-Hui , Wang Chii-Jye , Liu Chia-Chu , Wu Wen-Jeng , Huang Chun-Hsiung , Chang Lin-Li
Published: October 2008

Introduction

Vascular etiologies are the most common risk factors for erectile dysfunction (ED). Published studies have reported the associations of GNB3 C825T polymorphism with many vascular diseases. However, there are few reports about the association between this gene polymorphism and ED.

Aim

To investigate the associations among GNB3 C825T polymorphism, ED, and related risk factors in Taiwanese subjects.

Methods

A total of 155 patients with ED and 81 healthy controls were enrolled. All men had complete clinical histories taken. The 5-item International Index of Erectile Function (IIEF-5) was used to assess erectile conditions. The GNB3 C825T polymorphisms were determined using the polymerase chain reaction-restriction fragment length polymorphism method.

Main Outcome Measures

Patients with ED were defined as those having an IIEF-5 of <21.

Results

Two hundred thirty-six men were enrolled with a mean (standard deviation) age of 59.0 (10.2) years. Diabetes mellitus (DM), hypertension, and age were the three most significant independent risk factors for ED in a multiple logistic regression analysis (P = 0.008, 0.003, and 0.007, respectively). The prevalence of DM, hypertension, and body mass index (BMI) was significantly higher in GNB3 825T allele (CT/TT) carriers (P = 0.023, 0.049, and 0.035, respectively). There was no significant difference of ED prevalence between T and C allele carriers (69.1% vs. 56.2%, P = 0.07). However, the T allele carriers had significantly lower IIEF-5 scores (P = 0.02) associated with an increment of the T allele number (16.4[CC] vs. 14.4[CT] vs. 13.2[TT], P = 0.04).

Conclusions

In the present study, DM, hypertension, and BMI had significant associations with GNB3 825T allele carriers. Our results failed to show a significant association of the GNB3 C825T polymorphisms with ED prevalence. However, we cannot exclude that the presence of the T allele might influence the risk for ED severity indirectly through an increased risk for some vascular diseases.
Telemetric Intracavernosal and Intraspongiosal Pressure Monitoring
Authors: Shamloul Rany
Published: October 2008

Introduction

Despite the major breakthroughs basic research in erectile physiology experienced in the last, most of the methods used for quantitative assessment of erectile function in longitudinal studies suffer many drawbacks.

Objective

This review will focus on radiotelemetric assessment of intracavernosal (ICP) and intraspongiosal (ISP) regarding the technique, data collection, interpretation, and overall benefits.

Results

Telemetric recording of ICP and ISP allows for qualitative and quantitative assessment of erectile responses in experimental animals, a characteristic that is not possible using other techniques. This technique has many advantages that can collectively lead to production of high quality data regarding erection. The system suffers two drawbacks, its high cost and the need for surgical implantation of the transmitter.

Conclusion

The use of telemetric monitoring of ICP and ISP carries many advantages that will, hopefully, establish this technique as the gold standard method for assessment of erectile responses in the near future.
STRUCTURAL EMBEDDEDNESS AND SUPPLIER MANAGEMENT: A NETWORK PERSPECTIVE*
Authors: CHOI THOMAS Y. , KIM YUSOON
Published: October 2008

The concept of structural embeddedness refers to the importance of framing suppliers as being embedded in larger supply networks rather than in isolation. Such framing helps buying companies create more realistic policies and strategies when managing their suppliers. Simply put, the performance of a supplier is dependent on its own supply networks. By adopting the concept of structural embeddedness, we learn that a buying company needs to look at a supplier's extended supply network to arrive at a more complete evaluation of that supplier's performance. By doing so, a buying company may do a better job of selecting suppliers for long‐term relationships and may also find value in maintaining relationships with poorly performing suppliers who may potentially act as a conduit to other companies with technological and innovative resources.
STRATEGIC ALIGNMENT AND PURCHASING EFFICACY: AN EXPLORATORY ANALYSIS OF THEIR IMPACT ON FINANCIAL PERFORMANCE
Authors: BAIER CHRISTIAN , HARTMANN EVI , MOSER ROGER
Published: October 2008

Purchasing and supply management (PSM) has become a discipline of major strategic importance for effectively competing in today's global marketplace. Literature recognizes that the full value‐creation potential of the purchasing function can only be realized if its decisions and activities are aligned with the organization's overall strategic orientation. Despite general agreement on this matter, research and practice lacks knowledge on how exactly such an alignment can be achieved and what performance implications it has. Therefore, this article empirically investigates the alignment–performance link in PSM in a comprehensive manner. Drawing on the theory of production competence, we suggest that the relative fit between business strategy and purchasing strategy, labeled as strategic alignment, and between purchasing strategy and purchasing practices, referred to as purchasing efficacy, is key to achieving superior financial performance. Results from profile deviation analysis on data collected globally from 141 strategic business units (SBUs) with revenues greater than US$S3 billion support our hypotheses. Findings provide clear guidance to managers on how to design their purchasing strategies and practices to achieve maximum alignment and thus to effectively contribute to the SBU's financial success.
BUYER DEPENDENCY AND RELATIONAL CAPITAL FORMATION: THE MEDIATING EFFECTS OF SOCIALIZATION PROCESSES AND SUPPLIER INTEGRATION
Authors: PETERSEN KENNETH J. , HANDFIELD ROBERT B. , LAWSON BENN , COUSINS PAUL D.
Published: October 2008

Effective supply chain configurations are increasingly cited as a key driver of value creation. However, many supplier relationships are characterized by differing levels of dependence between the parties, which has the potential to influence the outcomes achieved. We build and test an empirical model to examine how buyer firms respond to dependency on a supplier by undertaking either socialization processes or closer integration in order to achieve relational capital. Using empirical data collected from 111 UK purchasing executives, a structural equation model is used to test the theoretical framework. The results provide support for four of the five hypotheses developed. Buyer firms facing high supplier dependency are found to undertake socialization processes to mitigate the dependency and generate relational capital. However, buyer dependency did not, in isolation, lead to increased levels of supplier integration. The study extends our understanding of how firms deal with asymmetric power within their supplier relationships and suggests important implications for both research and practice.
Online communities and the sharing of extraordinary restaurant experiences
Authors: Watson Pamela , Morgan Michael , Hemmington Nigel
Published: October 2008

The use of an experiential, postmodernist approach to studying hospitality markets opens many opportunities for research with an emphasis on the consumer, not on the product. This paper uses virtual ethnography to explore how a community of foodies creates meaning, understanding and identity as a consumer ‘tribe’, through nuances in communications on an Internet blog. These foodie customers derive added value from their ‘skilled consumption’, and this is evident in their knowledgeable contributions to discussion and sharing of their experiences of restaurants. The existence of the community to whom the experience will be reported alters the nature of the experience before, during and after the act of consumption, and gives additional meaning, as a symbol of shared values and identity.
The prognostic influence of prevertebral space involvement in nasopharyngeal carcinoma
Authors: Lee C.‐C. , Chu S.‐T. , Chou P. , Lee C.‐C. , Chen L.‐F.
Published: October 2008

Objectives:  The purpose of this study was to evaluate the effect of prevetebral space involvement on treatment outcomes in patients with nasopharyngeal carcinoma (NPC) who were treated with radiotherapy/concurrent chemoradiotherpy or concurrent chemoradiotherpy with adjuvant chemotherapy.

Design:  A retrospective review of case notes from the Kaohsiung Veterans General Hospital archives was performed.

Setting:  A medical centre in Taiwan.

Participants:  There were 145 newly diagnosed cases of NPC. Thirty‐nine patients were excluded because of the presence of distant metastasis at the time of presentation, loss of follow‐up and incomplete image information.

Main outcome measures:  Pearson’s chi‐square tests were used to analyse correlation between tumour invasion and prevetebral space involvement during univariate analysis and logistic regression was applied during multivariate analysis. Kaplan–Meier survival curves were constructed. Multivariate analysis was performed to examine the impact of various prognostic factors. Pearson’s chi‐square and Fisher’s exact test were also used to evaluate the correlation between failure patterns and treatment modality.

Results:  A total of 106 patients with newly diagnosed NPC were enrolled in this study. Forty‐three patients (41%) in this series were found to have prevertebral space involvement. Patients with prevertebral space involvement conferred a poor overall survival rate and metastasis‐free survival rate compared with those without prevertebral space invasion (P = 0.04 and 0.02 respectively). Multivariate analysis showed that prevertebral space invasion was associated with an increased risk for distant metastasis [hazard ratio (HR) 14, 95% confidence interval (CI) 1.0–17.4; P = 0.03)] and overall survival (HR 7, 95% CI 1.1–135; P = 0.04). In patients with prevertebral space involvement, their metastasis‐free survival rate, with and without adjuvant chemotherapy, was 100% and 72.7% (P = 0.047). This phenomenon was not observed in NPC patients without prevertebral space invasion.

Conclusions:  The present data revealed that prevertebral space involvement has a close relationship with survival rates and recurrence rates of patients with NPC. Nasopharyngeal carcinoma patients with prevertebral space involvement have more recurrence and poorer survival rates and should be the group to benefit from concurrent chemoradiotherapy followed by adjuvant chemotherapy. Inclusion of prevertebral space involvement may be needed to predict prognosis of NPC and help us to identify the high‐risk group.
Subsidiaries of Multinational Companies: Foreign Locations Gaining Competencies?
Authors: Fuchs Martina
Published: October 2008

In order to better understand the competitiveness of companies and with this their surrounding regions, economic geography and their related disciplines focus on topics, such as knowledge and learning. The article spotlights the acquisition of ‘competencies’ in foreign subsidiaries of multinational manufacturing companies and the necessary preconditions for such acquisition to take place. This topic is one of the most vibrant areas of research in economic geography and more specifically the debate on knowledge and learning, not least because such corporations have become exceptionally important actors in the world economy and thus extraordinarily significant for various regions.
Effect of UVR on Lake Water and Macrophyte Leachates in Shallow Andean‐Patagonian Lakes: Bacterial Response to Changes in Optical Features
Authors: Bastidas Navarro M. , Balseiro E. , Modenutti B.
Published: October 2008

The aim of this study was to identify bacterial responses in two shallow lakes from Patagonia to UV‐irradiated dissolved organic matter (DOM) coming from different sources. We carried out laboratory experiments in which natural lake water and Potamogeton linguatus leachates were irradiated (UVA‐340 fluorescent tubes Q‐Panel) or kept in darkness. Natural bacterial assemblages were then incubated in four treatments: natural lake water, irradiated lake water, macrophyte leachate and irradiated macrophyte leachate. We estimated bacterial abundance, composition and activity, and changes in the optical features of DOM. Our results showed that the addition of leachates caused an increase in the DOM mean molecular size. After UV exposure, a high bacterial activity was observed in lake water treatments. On the contrary, carbon uptake by bacteria was reduced in the irradiated leachate treatment. The degree of aromatization in the leachate treatments increased and thus may contribute to a dissolved carbon less available for bacterial activity. Regarding the bacteria assemblage we observed that β‐Proteobacteria outcompete the other groups in the leachate treatments, this group being more efficient at utilizing the high molecular weight DOM. These results highlight the importance of UVR interacting with different DOM sources in bacteria responses of shallow lakes.
Nanoscale Hydroxyl Radical Generation from Multiphoton Ionization of Tryptophan
Authors: Bisby Roger H. , Crisostomo Ana G. , Botchway Stanley W. , Parker Anthony W.
Published: October 2008

Exposure of solutions containing both tryptophan and hydrogen peroxide to a pulsed (∼180 fs) laser beam at 750 nm induces luminescence characteristic of 5‐hydroxytryptophan. The results indicate that 3‐photon excitation of tryptophan results in photoionization within the focal volume of the laser beam. The resulting hydrated electron is scavenged by hydrogen peroxide to produce the hydroxyl radical. The latter subsequently reacts with tryptophan to form 5‐hydroxytryptophan. The involvement of hydroxyl radicals is confirmed by the use of ethanol and nitrous oxide as scavengers and their effects on the fluorescence yield in this system. It is postulated that such multiphoton ionization of tryptophanyl residues in cellular proteins may contribute to the photodamage observed during imaging of cells and tissues using multiphoton microscopy.
Removal of the PsaF Polypeptide Biases Electron Transfer in Favor of the PsaB Branch of Cofactors in Triton X‐100 Photosystem I Complexes from Synechococcus sp. PCC 7002†
Authors: Agalarov Rufat , Byrdin Martin , Rappaport Fabrice , Shen Gaozhong , Bryant Donald A. , Van Der Est Art , Golbeck John H.
Published: October 2008

Continuous wave (CW) and transient electron paramagnetic resonance studies have implied that when PsaF is removed genetically, the double reduction of A1A is facile, the lifetime of A1A− is shorter and the ratio of fast to slow kinetic phases increases in PS I complexes isolated with Triton X‐100 (Van der Est, A., A. I. Valieva, Y. E. Kandrashkin, G. Shen, D. A. Bryant and J. H. Golbeck [2004] Biochemistry43, 1264–1275). Changes in the lifetimes of A1A− and A1B− are characteristic of mutants involving the quinone binding sites, but changes in the relative amplitudes of A1A− and A1B− are characteristic of mutants involving the primary electron acceptors, A0A and A0B. Here, we measured the fast and slow phases of electron transfer from A1B− and A1A− to FX in psaF and psaE psaF null mutants using time‐resolved CW and pump‐probe optical absorption spectroscopy. The lifetime of the fast kinetic phase was found to be unaltered, but the lifetime of the slow kinetic phase was shorter in the psaF null mutant and even more so in the psaE psaF null mutant. Concomitantly, the amplitude of the fast kinetic phase increased by a factor of 1.8 and 2.0 in the psaF and psaE psaF null mutants, respectively, at the expense of the slow kinetic phase. The change in ratio of the fast to slow kinetic phases is explained as either a redirection of electron transfer through A1B at the expense of A1A, or a shortening of the lifetime of A1A− to become identical to that of A1B−. The constant lifetime and the characteristics of the near‐UV spectrum of the fast kinetic phase favor the former explanation. A unified hypothesis is presented of a displacement of the A‐jk(1) α‐helix and switchback loop, which would weaken the H‐bond from Leu722 to A1A, accounting for the acceleration of the slow kinetic phase, as well as weaken the H‐bond from Tyr696 to A0A, accounting for the bias of electron transfer in favor of the PsaB branch of cofactors.
Immunophenotypic analysis of cerebrospinal fluid cell populations with the Cell‐Dyn Sapphire haematology analyser: method feasibility and preliminary observations
Authors: ADAM P. , SOBEK O. , SCOTT C. S. , DOLEZIL D. , KASIK J. , HAJDUKOVA L. , ADAM D.
Published: October 2008

Cerebrospinal fluid (CSF) samples (n = 50) from patients with neurological disease (bacterial infection, viral infection, neuroborreliosis and multiple sclerosis) were analysed to characterize cell populations by fluorescent immunocytometry with the CD‐Sapphire haematology analyser. Reagent combinations applied to all CSF samples comprised CD3/CD19/HLA‐DR and CD4/CD8, with some being further analysed using CD3/CD4, CD3/CD16 and CD3/CD25 protocols. Of the 50 samples, 11 were excluded because of high proportions of nonviable cells (n = 2) or insufficient cell numbers (n = 9). Apart from bacterial infection with granulocytosis, all diagnostic groups showed high proportions (51.4–77.0%) of CD3+ T cells. There was a modest association between T‐cell and B‐cell counts, but absolute B‐cell numbers exceeded 5 cells/μl in only 7/39 cases (neuroborreliosis, n = 6; bacterial meningitis, n = 1). CD3/Ia antigen (activation) co‐expression was low and only exceeded 5% in 7/39 samples with no diagnostic correlation. Primary CD4+ and CD8+ T‐cell subsets showed similar quantitative trends and CD4/CD8 co‐analysis revealed the presence in all diagnostic groups (neuroborreliosis and multiple sclerosis in particular) of a CD4+ CD8int fraction that was predominantly CD3+ and CD16− and had a morphological profile consistent with small lymphoid cells. Supplementary CD‐Sapphire cellular immunological analysis of most CSF samples is feasible using the procedure detailed in this communication.
Indole and 7‐hydroxyindole diminish Pseudomonas aeruginosa virulence
Authors: Lee Jintae , Attila Can , Cirillo Suat L. G. , Cirillo Jeffrey D. , Wood Thomas K.
Published: October 2008

Indole is an extracellular biofilm signal for Escherichia coli, and many bacterial oxygenases readily convert indole to various oxidized compounds including 7‐hydroxyindole (7HI). Here we investigate the impact of indole and 7HI on Pseudomonas aeruginosa PAO1 virulence and quorum sensing (QS)‐regulated phenotypes; this strain does not synthesize these compounds but degrades them rapidly. Indole and 7HI both altered extensively gene expression in a manner opposite that of acylhomoserine lactones; the most repressed genes encode the mexGHI‐opmD multidrug efflux pump and genes involved in the synthesis of QS‐regulated virulence factors including pyocyanin (phz operon), 2‐heptyl‐3‐hydroxy‐4(1H)‐quinolone (PQS) signal (pqs operon), pyochelin (pch operon) and pyoverdine (pvd operon). Corroborating these microarray results, indole and 7HI decreased production of pyocyanin, rhamnolipid, PQS and pyoverdine and enhanced antibiotic resistance. In addition, indole affected the utilization of carbon, nitrogen and phosphorus, and 7HI abolished swarming motility. Furthermore, 7HI reduced pulmonary colonization of P. aeruginosa in guinea pigs and increased clearance in lungs. Hence, indole‐related compounds have potential as a novel antivirulence approach for the recalcitrant pathogen P. aeruginosa.
Domestic and International Transracial Adoption: A Synopsis of the Literature
Authors: Tuan Mia
Published: October 2008

While adoptions are as ‘old as humanity itself’, transracial adoptions are a fairly recent phenomenon, particularly in the United States. This article reviews the state of transracial adoption research through an examination of the domestic and international transracial adoption literatures. Special attention is paid to the controversy that erupted in the 1970s over Black–White adoption placements and to the emergence of international adoption as the dominant form of transracial adoption.
Cybersex: The Impact of a Contemporary Problem on the Practices of Marriage and Family Therapists
Authors: Goldberg Peter D. , Peterson Brennan D. , Rosen Karen H. , Sara Mary Linda
Published: October 2008

The number of people accessing the Internet for sexual purposes (cybersex) has increased dramatically over the last 10 years. However, little research has been conducted to determine how frequently clients present for treatment with cybersex‐related issues. One hundred sixty‐four clinical members of the American Association for Marriage and Family Therapy participated in the current study, which was conducted to identify the impacts of cybersex on MFTs’ practices. Most respondents report seeing clients with cybersex‐related issues, with client numbers increasing over the past 2 years. Although most respondents felt prepared to diagnose and treat adults with cybersex problems, half felt unprepared to diagnose and treat children. Lastly, most respondents reported that their required college courses were not helpful in preparing them to diagnose and treat cybersex‐related problems. The implications of study findings are discussed.
Assisting A Concerned Person to Motivate Someone Experiencing Cybersex Into Treatment
Authors: Landau Judith , Garrett James , Webb Robert
Published: October 2008

Cybersex and Internet pornography addiction are new problem areas confronting couples and families. A most significant experience inducing family members to reach out to a therapist or an Interventionist for help with their addicted member is the realization that the individual they are living with has become a stranger. This article focuses on the changes in the attitude, emotions, and behaviors of the addicted individual from compulsive Internet pornography use and cybersex. Identifying these changes for the family members validates their experience of now living with a stranger. This article then presents the three‐level empirically based, manual‐driven method of Invitational Intervention, A Relational Intervention Sequence for Engagement (ARISE) as an effective tool for helping families to get their loved ones into treatment.
Regulation of smooth muscle contractility by the epithelium in rat vas deferens: role of ATP‐induced release of PGE2
Authors: Ruan Ye Chun , Wang Zhe , Du Jian Yang , Zuo Wu Lin , Guo Jing Hui , Zhang Jie , Wu Zhong Luan , Wong Hau Yin , Chung Yiu Wa , Chan Hsiao Chang , Zhou Wen Liang
Published: October 2008

Recent studies suggest that the epithelium might modulate the contractility of smooth muscle. However, the mechanisms underlying this regulation are unknown. The present study investigated the regulation of smooth muscle contraction by the epithelium in rat vas deferens and the possible factor(s) involved. Exogenously applied ATP inhibited electrical field stimulation (EFS)‐evoked smooth muscle contraction in an epithelium‐dependent manner. As the effects of ATP on smooth muscle contractility were abrogated by inhibitors of prostaglandin synthesis, but not by those of nitric oxide synthesis, prostaglandins might mediate the effects of ATP. Consistent with this idea, PGE2inhibited EFS‐evoked smooth muscle contraction independent of the epithelium, while ATP and UTP induced the release of PGE2from cultured rat vas deferens epithelial cells, but not smooth muscle cells. The ATP‐induced PGE2release from vas deferens epithelial cells was abolished by U73122, an inhibitor of phospholipase C (PLC) and BAPTA AM, a Ca2+chelator. ATP also transiently increased [Ca2+]iin vas deferens epithelial cells. This effect of ATP on [Ca2+]iwas independent of extracellular Ca2+, but abolished by the P2 receptor antagonist RB2 and U73122. In membrane potential measurements using a voltage‐sensitive dye, PGE2, but not ATP, hyperpolarized vas deferens smooth muscle cells and this effect of PGE2was blocked by MDL12330A, an adenylate cyclase inhibitor, and the chromanol 293B, a blocker of cAMP‐dependent K+channels. Taken together, our results suggest that ATP inhibition of vas deferens smooth muscle contraction is epithelium dependent. The data also suggest that ATP activates P2Y receptor‐coupled Ca2+mobilization leading to the release of PGE2from epithelial cells, which in turn activates cAMP‐dependent K+channels in smooth muscle cells leading to the hyperpolarization of membrane voltage and the inhibition of vas deferens contraction. Thus, the present findings suggest a novel regulatory mechanism by which the epithelium regulates the contractility of smooth muscle.
Modulation of murine gastric antrum smooth muscle STOC activity and excitability by phospholamban
Authors: Kim Minkyung , Hennig Grant W. , Park Kyungsik , Han In Soo , Smith Terence K. , Koh Sang Don , Perrino Brian A.
Published: October 2008

We investigated intracellular Ca2+waves, spontaneous transient outward currents (STOCs), and membrane potentials of gastric antrum smooth muscle cells from wild‐type and phospholamban‐knockout mice. The NO donor sodium nitroprusside (SNP) increased intracellular Ca2+wave activity in wild‐type antrum smooth muscle cells, but had no effect on the constitutively elevated intracellular Ca2+wave activity of phospholamban‐knockout cells. STOC activity was also constitutively elevated in phospholamban‐knockout antrum smooth muscle cells relative to wild‐type cells. SNP or 8‐bromo‐cGMP increased the STOC activity of wild‐type antrum smooth muscle cells, but had no effect on STOC activity of phospholamban‐knockout cells. Iberiotoxin, but not apamin, inhibited STOC activity in wild‐type and phospholamban‐knockout antrum smooth muscle cells. In the presence of SNP, STOC activity in wild‐type and phospholamban‐knockout antrum smooth muscle cells was inhibited by ryanodine, but not 2‐APB. The cGMP‐dependent protein kinase inhibitor KT5823 reversed the increase in STOC activity evoked by SNP in wild‐type antrum smooth muscle cells, but had no effect on STOC activity in phospholamban‐knockout cells. The resting membrane potential of phospholamban‐knockout antrum smooth muscle cells was hyperpolarized by approximately −6 mV compared to wild‐type cells. SNP hyperpolarized the resting membrane potential of wild‐type antrum smooth muscle cells to a greater extent than phospholamban‐knockout antrum smooth muscles. Despite the hyperpolarized membrane potential, slow wave activity was significantly increased in phospholamban‐knockout antrum smooth muscles compared to wild‐type smooth muscles. These results suggest that phospholamban is an important component of the mechanisms regulating the electrical properties of gastric antrum smooth muscles.
Electrophysiological events recorded at presynaptic terminals of the crayfish neuromuscular junction with a voltage indicator
Authors: Lin Jen‐Wei
Published: October 2008

The water‐soluble voltage indicator JPW1114 was used to stain thin axons and terminal varicosities of the crayfish neuromuscular junction. A slow, overnight injection protocol was developed to brightly stain fine structures without cytotoxicity. Fluorescence transients filtered at 2 kHz showed that the duration of terminal action potentials was shorter than that of those recorded in the main trunk of the axons. In addition, the repolarization phases of the terminal and axonal action potentials overlapped in time, suggesting that the entire axonal arborization repolarizes simultaneously. Manipulating resting membrane potential, ±15–20 mV, did not alter the peak level or duration of action potentials if they fired in isolation. A prolongation of action potential, by 23%, could be induced if a 10‐spike burst at 100 Hz was fired from depolarized membrane potential. No such change was observed when the high frequency train was fired from resting or hyperpolarized levels. Microelectrodes in the main trunk of axons typically recorded a depolarizing after‐potential (DAP) following an action potential initiated from resting membrane potential. The DAP could be inverted and enlarged by depolarization and hyperpolarization, respectively. Fluorescence transients recorded from terminals exhibited similar DAP characteristics. The ratio of DAP to action potential amplitude recorded from terminals was similar to that recorded from the main axon. Thus, the entire axonal arborization returned to resting level in a spatially uniform manner during the DAP. The functional significance of DAP is discussed in the light of these observations.
Structural Integrity Assessment of Steam Generator Tube by the Use of Heterogeneous Finite Element Method
Authors: Duan Xinjian , Kozluk Michael J. , Pagan Sandra , Mills Brian
Published: October 2008

Aging steam generator tubes have been experiencing a variety of degradations such as pitting, fretting wear, erosion-corrosion, thinning, cracking, and denting. To assist with steam generator life cycle management, some defect-specific flaw models have been developed from burst pressure testing results. In this work, an alternative approach; heterogeneous finite element model (HFEM), is explored. The HFEM is first validated by comparing the predicted failure modes and failure pressure with experimental measurements of several tubes. Several issues related to the finite element analyses such as temporal convergence, mesh size effect, and the determination of critical failure parameters are detailed. The HFEM is then applied to predict the failure pressure for use in a fitness-for-service condition monitoring assessment of one removed steam generator tube. HFEM not only calculates the correct failure pressure for a variety of defects, but also predicts the correct change of failure mode. The Taguchi experimental design method is also applied to prioritize the flaw dimensions that affect the integrity of degraded steam generator tubes such as the defect length, depth, and width. It has been shown that the defect depth is the dominant parameter controlling the failure pressure. The failure pressure varies almost linearly with defect depth when the defect length is greater than two times the tube diameter. An axial slot specific flaw model is finally developed.
Study of Parameter Effects on Residual Stresses and Thermal Deformation of Brazed Plate-Fin Structure Using Finite Element Method
Authors: Chen Hu , Gong Jian-Ming , Tu Shan-Tung , Geng Lu-Yang
Published: October 2008

The brazed plate-fin structure is the key component of a compact plate-fin heat exchanger. The residual stresses and thermal deformation induced by vacuum brazing may bring negative effects on the quality and the life of the plate-fin structure. Thus, it is important to optimize the brazing parameters in order to minimize such effects. This paper presents a three-dimensional finite element analysis for determining the residual stresses and thermal deformation of a three layered stainless steel plate-fin structure fabricated by nickel-based brazing. The features of residual stresses and thermal deformation distribution are discussed. The effects of three major brazing parameters including brazing temperature, clamping pressure load, and filler metal on the residual stresses and thermal deformation are investigated, respectively.
A 3-D Model for Evaluating the Residual Stress Field Due to Swage Autofrettage
Authors: Perry J. , Perl M.
Published: October 2008

In order to maximize the performance of modern gun barrels in terms of strength-to-weight ratio and total fatigue life, favorable compressive residual stresses are introduced to the inner portion of the barrel, commonly by the autofrettage process. There are two major autofrettage processes for overstraining the tube: the hydrostatic and the swage. There are several theoretical solutions for hydrostatic autofrettage based on Lamé’s solution and the von Mises or Tresca yield criteria. The residual stress field due to hydraulic autofrettage is treated as an axisymmetric two-dimensional problem solved in terms of the radial displacement solely. Once the Bauschinger effect was included in these models they yield very realistic results. Unlike in the case of hydraulic autofrettage, swage autofrettage needs to be modeled by a three-dimensional model. The present analysis suggests a new 3-D axisymmetric model for solving the residual stress field due to swage autofrettage in terms of both the radial and the axial displacements. The axisymmetric equilibrium equations are approximated by finite differences and solved then by Gauss–Seidel method. Using the new computer code the stresses, the strains, the displacements, and the forces are determined. A full-scale instrumented swage autofrettage test was conducted and the numerical results were validated against the experimental findings. The calculated strains, the permanent bore enlargement, and the mandrel pushing force were found to be in very good agreement with the measured values.
Harmonic Analysis of a Cylinder Cluster in Square Confinement With Position-Dependent Fluid Damping
Authors: Pomirleanu Radu
Published: October 2008

The vibration of cylinder clusters in axial flow is a classical engineering problem, with applications to nuclear fuel rods and steam generator tubes. The classical method of solution to this problem consists in development of modal analysis of the entire cluster including structural characteristics and fluid-elastic effects due to the presence of the dense medium in the space between cylinders, followed by a forced-vibration analysis. It is shown here that the out-of-phase fluid-elastic effects (added damping) are dependent on the position of cylinders within the bundle, not unlike the already proven in-phase effects (added mass). A two-dimensional arbitrary Lagrangian Eulerian (ALE) finite-element analysis is used to compute the hydrodynamic coupling effects in a 5×5 rod cluster subject to single-phase parallel flow. These motion-dependent effects are subsequently embedded into the equations of motion for scaled-down array of nuclear fuel rods, which are structurally modeled as variable-mass Euler–Bernoulli beams on elastic supports. The modal and harmonic analyses developed on the basis of these equations shows that the rod response is affected by the rod position within the cluster, relative to the confinement.
Elastoplastic Analysis of a Miniature Circular Disk Bending Specimen
Authors: Verma Vishnu , Ghosh A. K. , Behera G. , Sharma Kamal , Singh R. K.
Published: October 2008

The miniature disk bending test is used to evaluate the mechanical behavior of irradiated materials and their properties (e.g., yield stress and strain hardening exponent) to determine mainly ductility loss in steel due to irradiation from the load-deflection behavior of the disk specimen. In the miniature disk bending machine the specimen is firmly held between the two horizontal jaws of punch, and an indentor with a spherical ball travels vertically. Analytical solutions for large amplitude plastic deformation become rather unwieldy. Hence, a finite element analysis has been carried out. The finite element model considers contact between the indentor and test specimen, friction between various pairs of surfaces, and elastic plastic behavior. This paper presents the load versus deflection results of a parametric study where the values of various parameters defining the material properties have been varied by ±10% around the base values. Some well-known analytical solutions to this problem have also been considered. It is seen that the deflection obtained by analytical elastic bending theory is significantly lower than that obtained by the elastoplastic finite element solution at relatively small values of load. The finite element solution has been compared with one experimental result and values are in reasonably good agreement. With these results it will be possible to determine the material properties from the experimentally obtained values of load and deflection.
Characteristics of the Suppression of Sloshing in a Vessel by a Bulkhead
Authors: Kobayashi Nobuyuki , Watanabe Masahiro , Honda Tomokazu , Ohno Katsunori
Published: October 2008

This paper investigates the characteristics of the suppression of sloshing in a vessel by a bulkhead that divides the vessel vertically into two sections but allows communication between two sections at the lower part of the vessel. The sloshing behavior is thus separated into a U-tube sloshing mode and a sloshing mode confined to each of the separated compartments. The effect of the aperture height beneath the bulkhead and the amplitude of the excitation on the characteristics of the suppression of the U-tube sloshing mode is investigated experimentally. As a result, the following phenomena are clarified. Three types of flow patterns were observed: flow pattern A, with unsteady vortices, flow pattern B, with a single swirl and a vortex, and flow pattern C, with twin swirls. The flow pattern changes from A to B or C as the amplitude of the excitation increases. The damping ratio with the bulkhead is much larger than that without the bulkhead. The damping generated by the bulkhead depends on the amplitude of the excitation. The flow pattern plays an important role in the dissipation of the energy of the sloshing. In particular, the vortices and swirls increase the rate of energy dissipation of the sloshing.
A Novel and Simple Approach for Predicting Creep Life Based on Tertiary Creep Behavior
Authors: Zarrabi Khosrow , Ng Lawrence
Published: October 2008

The creep of materials is a research topic of major significance in the life assessment and design of many modern engineering components of advanced technology such as power generation plant, chemical plant, gas turbines, jet engines, spacecrafts, and components made of plastics and polymers. To predict the creep life of such components, one necessary ingredient is a creep damage model. The current creep damage models are either too cumbersome to be readily employed and/or not sufficiently accurate for practical applications. This paper describes a new multiaxial creep damage model that alleviates the major shortcomings of the existing models. Yet it is relatively simple and accurate and is readily applicable to industrial cases.
Failure Modes of Perforated Material Under Finite Deformation
Authors: Duan Xinjian , Weck Arnaud , Wilkinson David S. , Metzger Don R.
Published: October 2008

Local deformation due to the interaction of small scale features such as voids or hard particles is expected to have a significant influence on the failure mode of a material. To this end, the fracture pattern of a perforated aluminum sheet is studied experimentally and numerically using finite element models on two different length scales: a full-scale structural model and a local cell model based on large deformation theory. Through the appropriate application of boundary conditions, the more efficient local cell model is shown to produce almost the same results as the full structural model. It is also found that the failure path is significantly affected by the loading conditions (uniaxial versus biaxial) and the hole distribution pattern. By plotting the instantaneous contours of the plastic strain rate, the fracture path can clearly be distinguished by the time that the overall engineering strain reaches approximately 3%. This model developed here has great potential to assess the integrity of high pressure components such as tubesheet.
Comparative study of thermally cured and electron-beam-exposed hydrogen silsesquioxane resists
Authors: Choi Sookyung , Word Michael J. , Kumar Vipan , Adesida Ilesanmi
Published: October 2008

A comparative study of the changes in the chemical structure and properties of hydrogen silsesquioxane (HSQ) resists induced by thermal curing and electron-beam exposure has been conducted. Studies using Fourier transform infrared (FTIR) spectroscopy suggested similar behavior in the redistribution of bonds for both processes. Quantitative analysis of both spectra revealed the existence of a critical temperature and electron dose for the achievement of development for pattern generation. As a complementary technique, x-ray reflectivity measurements were performed to monitor changes in the film density. Notwithstanding the similar changes in bond redistribution observed from the FTIR spectra for both thermal curing and electron-beam exposure, the film densification processes seem to occur in quite distinctive fashions. This was confirmed through dry etching experiments; the results of which were consistent for both Freon and Cl2∕Ar reactive ion etching. While effective film densification occurred only at curing temperatures above 400°C, insignificant changes in density and etch durability were observed for electron-beam-exposed HSQ resists at electron doses commonly used for pattern generation. Wet etching characteristics engendered by hydrofluoric acid showed that both chemical bond redistribution and densification lead to decreases in etch rates.
Plasma etch removal of poly(methyl methacrylate) in block copolymer lithography
Authors: Ting Yuk-Hong , Park Sang-Min , Liu Chi-Chun , Liu Xiaosong , Himpsel F. J. , Nealey Paul F. , Wendt Amy E.
Published: October 2008

Polystyrene-block-poly(methyl methacrylate), (PS-b-PMMA) diblock copolymer is a promising lithography alternative for nanometer scale features. The two components segregate into nanoscale domains when the polymer solution is spun on to form a thin film and annealed above the glass transition temperatures of both components. Preferential removal of PMMA domains through plasma etching to leave behind a PS mask for subsequent etching of underlying layers is the focus of this work. The quality of the PS mask is characterized by the thickness and lateral dimension of the PS structures after removal of the PMMA, as well as the smoothness of their surfaces. The effects of different plasma chemistries including O2, Ar/O2, Ar, CF4, and CHF3/O2 on etch selectivity and surface/sidewall roughness for PS and PMMA have been characterized. Ar/O2 produced the overall best results for the range of conditions studied.
Study of substrate-directed ordering of long double-stranded DNA molecules on bare highly oriented pyrolytic graphite surface based on atomic force microscopy relocation imaging
Authors: Wang Huabin , An Hongjie , Zhang Feng , Zhang Zhixiang , Ye Ming , Xiu Peng , Zhang Yi , Hu Jun
Published: October 2008

Usually, long double-stranded DNA molecules exhibit an aggregated or a random spreading behavior when deposited on a highly ordered pyrolytic graphite (HOPG) substrate. In this article, the authors report a novel phenomenon where randomly oriented DNA strands can gradually be rearranged into two-dimensional ordered nanostructures under the operation of repeatedly rotating a water droplet on the DNA sample. The process of DNA rearrangement was traced by using atomic force microscopy relocation imaging. The orientation of the ordered DNA strands shows a threefold symmetry consistent with the underlying atomic lattice of the HOPG substrate, signifying a substrate-directed ordering process. The relevant mechanism is discussed.
Growth of nitrogen doped ZnO films through a nitrogen diffusion process from WN films formed by a cosputtering technique
Authors: Lee Jonghyun , Ha Jaehwan , Hong Jinpyo , Cha Seungnam , Paik Ungyu
Published: October 2008

High quality nitrogen doped ZnO films were fabricated on glass substrates by allowing nitrogen atoms from a pregrown tungsten nitride (WN) to be activated and diffused into a pure ZnO film during an in situ post-thermal annealing process. The N doped ZnO film exhibited reproducible electrical properties including a Hall concentration of 3.69×1018 cm−3, a mobility of 1.35 cm2/Vs , and a resistivity of 10 Ω cm at room temperature, along with corresponding structural results. Further investigation using ZnO p-n homojunctions, which displayed good I-V characteristics with a turn-on voltage of about 3 V, demonstrated that the p-type ZnO growth process can simply form p-type ZnO:N.
Optical properties and critical-point energies of BaTiO3 (001) from 1.5to5.2eV
Authors: Choi S. G. , Dattelbaum A. M. , Picraux S. T. , Srivastava S. K. , Palmstrøm C. J.
Published: October 2008

The authors report optical properties and interband-transition critical-point energies of bulk BaTiO3 (001). Room-temperature pseudodielectric function spectrum ⟨ε(E)⟩=⟨ε1(E)⟩+i⟨ε2(E)⟩ from 1.5to5.2eV has been measured by spectroscopic ellipsometry. In order to obtain the best approximation to the intrinsic dielectric response ε(E), the artifacts from surface overlayer in the measured ⟨ε⟩ have been minimized by the premeasurement surface treatments as well as the postmeasurement modeling procedure. The measured spectrum exhibited the critical-point structures for four interband transitions and their accurate energy values were obtained by applying the critical-point parabolic band model to the numerically calculated second-energy derivatives of the experimental data. The critical points at 3.27, 3.92, and 4.90eV were identified as the E1, A1, and A2 interband transitions from early optical reflectance studies. We also report a new critical-point structure at 3.63eV.