bluuebunny/crossref_metadata_2025 huggingface dataset:
Cholangiocyte proliferation and liver fibrosis
Authors: Glaser Shannon S. , Gaudio Eugenio , Miller Tim , Alvaro Domenico , Alpini Gianfranco
Published: February 2009

Cholangiocyte proliferation is triggered during extrahepatic bile duct obstruction induced by bile duct ligation, which is a common in vivo model used for the study of cholangiocyte proliferation and liver fibrosis. The proliferative response of cholangiocytes during cholestasis is regulated by the complex interaction of several factors, including gastrointestinal hormones, neuroendocrine hormones and autocrine or paracrine signalling mechanisms. Activation of biliary proliferation (ductular reaction) is thought to have a key role in the initiation and progression of liver fibrosis. The first part of this review provides an overview of the primary functions of cholangiocytes in terms of secretin-stimulated bicarbonate secretion – a functional index of cholangiocyte growth. In the second section, we explore the important regulators, both inhibitory and stimulatory, that regulate the cholangiocyte proliferative response during cholestasis. We discuss the role of proliferating cholangiocytes in the induction of fibrosis either directly via epithelial mesenchymal transition or indirectly via the activation of other liver cell types. The possibility of targeting cholangiocyte proliferation as potential therapy for reducing and/or preventing liver fibrosis, and future avenues for research into how cholangiocytes participate in the process of liver fibrogenesis are described.
Nursing in the Millennium
Authors: Clifford Collette , M Warner , M Longley , E Gould , A Picek
Published: February 2009

As we start out on our path into the millennium, there are a number of key issue we need to consider about our future in nursing. Whilst many readers may groan at such a statement it is worth remembering the difference between nursing at the beginning of the last century and today. Clearly nothing is static, change is inevitable and, if we want to be proactive in leading change, we need to consider the options open to us now so that we drive the agenda for nursing in this century rather than letting others do as has sometimes been the case in the past.
Meet The Committee
Authors: Chiswell Chris
Published: February 2009

I started my nursing career in Bristol as pupil nurse in 1979. On qualifying, I worked in an orthopaedic ward for a year, got hooked and went off to do the course. From there I moved to Poole, spent two happy years working on a trauma unit with great views of the bay and spent most of my spare time either lying on the beach or partying hard as you do when you are young and single. I met my other half and moved to London taking a five year break - what bliss. I decided to return to work in 1989, dabbling a little on the nursing bank before taking a permanent contract. There followed eight years at Farnborough in Kent. Six of these flew by working with an excellent team of nursing and medical staff on one of the few remaining, untouched ENT units that hasn't been swallowed into ‘general surgery’. Here I re entered the theatre world (Not visited since my training days) learned to do it properly and at the time gained a great deal of experience recovering patients with potential airway problems whilst keeping my fingers crossed that they did not actually develop any. I was also both supported and encouraged to undertake and complete the conversion course and decided I may as well get the ENB 998 over and done with soon after. Ward management skills come next - you know how it goes, the off duty, answering the phone, having your name called over and over again - that sort of thing. In 1997, we decided to move to the country for some fresh air and life out of the fast lane.
Multidisciplinary working and learning- the way forward
Authors: Rowbotham David J
Published: February 2009

After organising, chairing and teaching on a recent multidisciplinary workshop on postoperative pain in Munich, I was to attend a Beer Hall in the centre of this fine city. As I sat there, sipping the occasional aliquot of fine German lager, I found myself pondering over many things. As a result of tiredness and intellectual exhaustion, my recollection of my thoughts at that time is not complete.
The Recovery Room
Authors: Radford Mark
Published: February 2009

The speciality of anaesthetic and recovery nursing has grown from a foundation of hard evidence that the majority of anaesthetic complications occur in the post operative period, and there is a need for a highly trained and experienced nurse with skills and expertise in caring for patients during this critical period. This development during the late 60's and early 70's was shaped by anaesthetists and has over the years been continually developed and enhanced by nursing. Post Anaesthetic nursing practice is now an integral part of the perioperative process, with some suggesting that recovery nursing is largely distinct from the other perioperative skills and should be treated as such in terms of education and planning.
Thoughts by Agency Jane August 2000
Authors: Bovey J
Published: February 2009

Jane Bovey has long been a member of BARNA, and has recently left her job in the private sector as a recovery nurse to work with an agency. Jane decided to write a column in the journal to express concerns felt by many nurses working in anaesthetics and recovery. Jane also wanted to promote debate on some contentious issues, and welcomes replies to her column. If you have a reply, send an email: theeditor.bjarn@k-2.org.uk or BJARN, 6 Bromyard Avenue, Walmley, Sutton Coldfield, B76 IRQ. The views expressed in this column are entirely of the author, and do not necessarily reflect those held by the British Anaesthetic & Recovery Nurses Association.
A Nurse led Innovation in the Administration of Epidural Infusions
Authors: Wootton Heidi
Published: February 2009

Whilst there is a multitude of literature available on the efficacy of continuous epidural infusions following major surgery (Buggy & Smith 1999, Rawal 1998, Macintyre & Ready 1997), little attention is paid to the administration of these infusions. Some hospitals keep patients in HDU/ITU (Audit Commission, 1997) following surgery because of problems in administration of epidural infusions on the ward. This article describes an innovation in epidural administration which has been successfully implemented in two NHS Trusts. The system is safe, cost effective and allowed us to use our existing syringe pumps.
Students' Perceptions of Day Surgery
Authors: Cahill Heather
Published: February 2009

At departmental meetings, it has long been commonplace for staff to play ‘Lingo Bingo’. The rules of the game are simple; one can play alone, but it is much more fun in a team. First select one word from an apparently endless list of irritating and pompous terminology and then agree a number between 5 and 10. Then sit through the meeting, counting how many times people at the gathering use the selected term. When they reach the number selected, shout Bingo! And wait for the reaction. It seems to me that NHS managers, educational institutions and of course, health ministers are all playing the game.
Post Anaesthesia Care for the Obstetrics Patient
Authors: Radford Mark
Published: February 2009

In many ways anaesthesia has become a victim of its own success. In the eyes of many, both clinicians and patients alike, anaesthesia has become safe and predictable. The demands placed upon anaesthesia services in the hospitals is increasing. Anaesthesia provision has diversified into many fields, and the input of the anaesthesia team is noticeable in many areas of the hospital including A&E, wards, radiology and Coronary care units.
BARNA Conference 2001
Authors: Behar-Spicer Cina , Chiswell Chris
Published: February 2009

Tne 15th Annual BARNA Conference was held at the Clarendon Suites in Edgbaston, Birmingham on 26th & 27th June 2001.
An introduction to cardiac monitoring and rhythm interpretation
Authors: Spiers Christine , Stinchcombe Emma
Published: February 2009

This article is the first in a series which will explore the identification and management of cardiac arrhythmias within the peri-operative care setting. To improve patient safety, the number of patients who are monitored within the recovery room is rising, whilst cardiac monitoring remains a fundamental requirement for patient care during the anaesthetic phase. Therefore, the role of the peri-operative care nurse requires an ability to interpret cardiac arrhythmias and to subsequently instigate the appropriate management.

The purpose of this preliminary article is to establish the basic principles that underpin the identification and management of arrhythmias. Cardiac physiology is reviewed and then applied to the derivation of the waveforms of the normal ECG. The article continues with a summary of accurate electrode placement and some tips for troubleshooting in the presence of ‘artifact’. A systematic analysis tool, which can be easily applied to clinical practice, completes the article.
Care of the High Dependency Patient
Authors: Kent Elaine
Published: February 2009

Recent government changes to Critical Care in the Health Service have resulted in an increase in the numbers of critical care patients being nursed in Post Anaesthetic Care Units (PACU). Many recovery nurses have had to increase their knowledge and skills accordingly. This article will analyse the high dependency nursing care given to a patient in the PACU necessitated by the haemodynamic compromise of the patient's cardiovascular system following surgery. The need for admission to a high dependency bed will be discussed along with the assessment of shock, tissue perfusion, fluid replacement, and any pharmacological intervention. Psychological, social and ethical issues relating to the patient and family will also be identified. Concentrating on the first 24 hours post-operatively, a careful discussion and analysis of the clinical management given will be made, with reference to the clinical and physiological measurements. After an evaluation and reflection of the medical and nursing care given to the patient, this article will conclude with a brief reiteration of the key issues.
Arrhythmia Interpretation in the Perioperative Arena - Part 3 Ventricular Arrhythmias
Authors: Stinchcombe Emma
Published: February 2009

This article on the assessment and management of ventricular arrhythmias is the third in a series exploring cardiac monitoring in the perioperative care setting. Ventricular arrhythmias, which arise within the ventricular myocardium, can be potentially lifethreatening. Many of the causes of these arrhythmias can be found in the peri-operative setting and thus it is essential that practitioners are able to differentiate the rhythms and respond appropriately.
Research – A Systematic Approach for Nursing Specialities Part I
Authors: S Maura
Published: February 2009

This overview of the research process is for nurses who have either not had a formal course of study in the area, or have not thought about the process in some time. Using a systematic method of viewing the research process should improve understanding. By knowing how question type determines design, and ultimately how results are structured, nurses will be better able to engage in the process as knowledgeable participants. Using this framework should allow those, who wish to do so, to further study the numerous variations in designs and nuances within in each level
International Perianesthesia Collaboration A UK Circle of Influence
Authors: Brady Joni M.
Published: February 2009

It has been said that where one door closes, another opens. I experienced such a phenomenon in June. A humanitarian medical team mission, with which I was scheduled to participate in Romania, was unfortunately cancelled due to world events. Within days of the cancellation news the latest edition of the Journal of PeriAnesthesia Nursing (JoPAN) arrived in my mailbox.
NHS Modernisation Programme: A Guide with Links to Government NHS Web Sites for Further Information
Authors: Smedley Pat
Published: February 2009

The rapid pace of change in the National Health Service (NHS) over the last five years has resulted in significant alterations to the way health care is, and will be delivered in the UK. The essential aims are to cut down waiting times, put more money into the system &C use it more effectively to improve patient experience through setting practice standards/maximising on staff potential/empowering patients/funding more beds and much more.
The Impact of Culture on Anaesthetic Practice
Authors: Cowan David T.
Published: February 2009

IN debating the issue of whether or not nursing care should be perceived within a framework of cultural competence, this paper briefly describes the background of this approach to nursing, and as an exemplar, discusses how culture can impact on the practice of anaesthetics and peri–anaesthetic care. This is illustrated through drawing on my own transcultural experiences while employed for nearly five years as a non–physician anaesthetist in Saudi Arabia and may therefore be of interest to those practitioners involved in the delivery of anaesthetics and peri–anaesthetic care.
Lone Working in the Post Anaesthetic Care Unit is Patient Care Compromised?
Authors: Guyan P. G.
Published: February 2009

This article discusses staffing levels in the Post Anaesthetic Care Unit, following key recommendations that have been documented in response to the changing nature of both anaesthesia and surgery. An audit was carried out at the unit in York Hospital to determine whether the staff felt that patient care and staff vulnerability was compromised during times when the Recovery nurse worked alone.
Parental Presence within the Post-Anaesthetic Care Unit
Authors: Whitehurst Eric
Published: February 2009

As health care providers our philosophy is to deliver the very highest quality of care to our patients. However within many hospitals there are not firm policies to allow family members to see their loved ones in the immediate postoperative period. Thus parents are routinely not being encouraged to comfort and support their children within the Post Anaesthetic Care Unit. The evolution of ‘family centred’ care should result in parents being encouraged to be with and care for their children during hospitalisation. This has been found to be beneficial to all parties. Whilst parental presence in the anaesthetic room has become more accepted practice the same cannot be said of Post Anaesthetic Care Units despite the recommendations made by the Department of Health [1991] and ‘The Patients’ Charter [1996]. Why does this situation exist? Is it due to preconceived attitudes of the staff involved, parental ignorance or historical reasons? This article will examine available research and attempt to identify possible reasons why such situations exist within many Post Anaesthetic Care Units and suggest possible solutions.
Risk Assessment in the Post Anaesthetic Care Unit Using Critical Incident Analysis
Authors: Deann-Valentine Yvette
Published: February 2009

It is generally accepted that the theatre is a highly technical and complex environment where clinical risks need to be managed effectively to ensure safe practice and to limit liability and litigation. Although anaesthesia and post anaesthesia care has long been the focus of risk management, the potential for errors and adverse events remains high. When errors occur, it is important to analyse the causes, so that preventative measures can be taken and similar incidents do not reoccur. This article sets out to examine and evaluate the process of reflection using a critical incident approach. A model of reflective practice, as suggested by Johns [1996] has been used to structure this paper. A critical incident is described and key issues arising from it are discussed and reflected upon. This incident was chosen because important clinical and risk management issues were highlighted.
Post Anaesthetic Shaking
Authors: Brown Maria E.
Published: February 2009

Bastien (1950), cited by Horn et al (1998b) first described post anaesthetic shaking over fifty years ago. Although the existence of this phenomenon is well documented, definition, cause and the benefits of individual treatments remain open for debate (Fotheringham 1998). However the mechanism for Post Anaesthetic Shaking (PAS) remains unclear (Sessler and Sessler 1998b), although the literature does suggest hypothermia is a factor, as too might be pain and stress. There are many variables effecting whether a patient will develop PAS. As much controversy remains regarding this condition the rationale for undertaking this paper is to improve care by broadening knowledge and thus allowing rapid and effective treatment to reduce the discomfort and distress experienced by the patient. This article is presented as a critical incident. Implications, for practice arising from this work suggest that more frequent monitoring and early intervention would enhance the available treatments. Further to this it appears that warming patients preoperatively, particularly those groups known to be at risk would reduce the incidence of hypothermia and consequently post anaesthetic shaking. Recommendations for future research would be further investigation in to the suggestion that body temperature need only vary by 0.2°C to affect a bodily response (such as shivering).
Haemodynamic Monitoring in Theatre
Authors: Clinton Heidi
Published: February 2009

The number of devices available to monitor the haemodynamic status of patients is increasing. Practitioners need to be aware of the non-invasive and invasive methods available in order to care for their patients safely and effectively. This article reviews a number of noninvasive measurements of haemodynamic function, in addition to invasive methods such as arterial blood pressure, central venous pressure and pulmonary artery pressure monitoring. It is argued that using these methods in combination provides a comprehensive haemodynamic assessment.
Immediate Post Anaesthetic Recovery
Authors: Oakley Melanie
Published: February 2009

The Association of Anaesthetists approached BARNA for comment on this paper prior to its publication. This work will review the content of the document published in September 2002. The Association has published two similar documents prior to this in 1985 and 1993. They recognise that the post anaesthetic care of a patient has evolved rapidly since the last document was published. The current document is a response to the rapidly changing nature of anaesthesia and surgery and the direct impact that has on the post anaesthetic care unit, the patients and the staff who work within the unit. A summary of the key recommendations can be seen below and these will be expanded upon and discussed.
A randomized controlled trial to assess an anger management group programme
Authors: Naeem Farooq , Clarke Isabel , Kingdon David
Published: February 2009

We describe the results of a randomized controlled trial to assess effectiveness of an anger management group programme, employing a cognitive behavioural framework that was run by the Psychology Service. The treatment group was compared with a control group on a waiting list. The trial was performed at the Southampton CBT Service. The treatment group received a cognitive behavioural anger management programme, initially based on Novaco's approach, but with further development of the motivational components. The control group received no treatment and was on a waiting list. The Novaco Anger Assessment Scale (NAS), State-Trait Anger Expression Inventory (STAXI), Evaluative Beliefs Scale (EBS), Hospital Anxiety and Depression Scale (HAD) and the Clinical Outcomes in Routine Evaluations (CORE) were used to measure anger, belief about self and others, anxiety and depression, and physical and psychological wellbeing. Clients in the anger management group showed statistically significant changes on STAXI, NAS, CORE and EBS subscales at the end of the therapy. The change in depression and anxiety on HAD (depression and anxiety) was not statistically significant. It was not possible to carry out analyses at follow-up due to high dropout rates. We concluded that an anger management programme using CBT was helpful in reducing anger and overall psychopathology.
Schemas defined
Authors: James Ian , Todd Helen , Reichelt F. Katharina
Published: February 2009

A range of clinicians (n = 72) were asked to provide a definition of a schema. The participants were selected from different parts of the broad church of the CBT community, with all having received some training in CBT – although only 26.4% had a formal CBT qualification. Fourteen themes were identified, suggesting that the concept is perceived to be complex. However, the mean number of themes identified per clinician's definition was small: 2.86 (mode = 2). We consider this finding reflects a problem concerning a lack of clarity with respect to the use of one of the key concepts in CBT.
Using a structured treatment, Friends for Life, in Norwegian outpatient clinics: results from a pilot study
Authors: Martinsen Kristin D. , Aalberg Marianne , Gere Martina , Neumer Simon-Peter
Published: February 2009

CBT treatment programmes for children and adolescents with anxiety disorders are promising as indicated by efficacy research. Replicating this research in ordinary clinical care is crucial in order to establish the validity of these results and disseminate empirically based treatments to practitioners. This paper presents the first experiences of using a structured programme, the Friends for Life manual, in ordinary clinical care in Norway targeting anxiety problems in children aged between 7 and 12 years. The effects of the treatment are presented as multiple single-case studies. Clinical meaningful change is considered from two perspectives; diagnostic change and changes in self-report measures. At a statistical significance level the treatment effect can be characterized as modest. Independent of the symptom reduction, the children, families and therapist are in the main satisfied with the structured approach indicating the acceptability of the programme.
Uncertainty in early warning predictions of engineering ground motion parameters: What really matters?
Authors: Iervolino Iunio , Giorgio Massimiliano , Galasso Carmine , Manfredi Gaetano
Published: February 2009

From the engineering perspective, the effectiveness of earthquake early warning systems (EEWS) depends only on the possibility of immediately detecting the earthquake and estimating the expected loss at a location of interest, in order to undertake actions to manage/mitigate the risk before the strike. The simplest proxy for the earthquake's destructive potential is the peak ground acceleration (PGA), which is predicted through probabilistic seismic hazard analysis in the framework of EEW. In this paper, the effects of different sources of uncertainty on the prediction of PGA are assessed with reference to the ISNet (Irpinia Seismic Network) EEWS. First the analyses show how the uncertainty of the ground motion prediction equation (GMPE) dominates those of magnitude and distance, almost independently of the information available for the event. Secondly, based on these findings, information‐dependent lead‐time maps are provided for the Campania (southern Italy) region. Finally, different real‐time magnitude estimators are compared in terms of errors in the prediction of PGA, as a more efficient estimator may give additional lead‐time for risk reduction.
Alveolar ridge repair in a canine model using rhTGF‐β1 with barrier membranes
Authors: Ruskin James D. , Hardwick Ross , Buser Daniel , Dahlin Christer , Schenk Robert K.
Published: February 2009

In both normal and membrane‐assisted situations, healing events are modulated by the activity of endogenous protein molecules known as cytokines. Due to its mitogenic and chemotactic characteristics, the addition of rhTGF‐β1 should increase the rate of osteogenesis or increase the potential for bone regeneration in oral osseous defects. This study evaluates the effects of an osteoconductive biodegradable matrix incorporating human recombinant transforming growth factor beta 1 (rhTGF‐β1) in conjunction with barrier membranes on bone regeneration in canine alveolar ridge defects. A matrix of calcium carbonate and hydroxyethyl starch served as the carrier for test concentrations of 2.0 μg/0.8 ml and 20.0 μg/0.8 ml of rhTGF‐β1. One surgically prepared site in each of 13 adult male foxhounds received 1 of 4 experimental treatment regimens, with 6 sites utilizing barrier membranes. Four sites in each of 2 additional animals, two containing carrier matrix only and 2 with the additional barrier membrane, served as controls. Specimens were retrieved after 2 months of healing and processed for routine light microscopy. The quantity and composition of regenerated bone was examined. Analysis of variance revealed a statistically significant increase (P<0.05) in the development of bone with the use of rhTGF‐β1. Likewise, a statistically significant increase in regeneration was found in membrane‐protected sites over non‐membrane‐protected sites. No statistically significant difference was noted between the low and high dose treatments. The authors conclude that the use of rhTGF‐β1 in conjunction with a barrier membrane greatly enhances bone regeneration in osseous oral defects.
Dielectric relaxation of cytochrome c oxidase: Comparison of the microscopic and continuum models
Authors: Leontyev I. V. , Stuchebrukhov A. A.
Published: February 2009

We have studied a charge-insertion process that models the deprotonation of a histidine side chain in the active site of cytochrome c oxidase (CcO) using both the continuum electrostatic calculations and the microscopic simulations. The group of interest is a ligand to CuB center of CcO, which has been previously suggested to play the role of the proton pumping element in the enzyme; the group is located near a large internal water cavity in the protein. Using the nonpolarizable Amber-99 force field in molecular dynamics (MD) simulations, we have calculated the nuclear part of the reaction-field energy of charging of the His group and combined it with the electronic part, which we estimated in terms of the electronic continuum (EC) model, to obtain the total reaction-field energy of charging. The total free energy obtained in this MDEC approach was then compared with that calculated using pure continuum electrostatic model with variable dielectric parameters. The dielectric constant for the “dry” protein and that of the internal water cavity of CcO were determined as those parameters that provide best agreement between the continuum and microscopic MDEC model. The nuclear (MD) polarization alone (without electronic part) of a dry protein was found to correspond to an unphysically low dielectric constant of only about 1.3, whereas the inclusion of electronic polarizability increases the protein dielectric constant to 2.6–2.8. A detailed analysis is presented as to how the protein structure should be selected for the continuum calculations, as well as which probe and atomic radii should be used for cavity definition. The dielectric constant of the internal water cavity was found to be 80 or even higher using “standard” parameters of water probe radius, 1.4Å, and protein atomic radii from the MD force field for cavity description; such high values are ascribed to the fact that the standard procedure produces unphysically small cavities. Using x-ray data for internal water in CcO, we have explored optimization of the parameters and the algorithm of cavity description. For Amber radii, the optimal probe size was found to be 1.25Å; the dielectric of water cavity in this case is in the range of 10–16. The most satisfactory cavity description, however, was achieved with ProtOr atomic radii, while keeping the probe radius to be standard 1.4Å. In this case, the value of cavity dielectric constant was found to be in the range of 3–6. The obtained results are discussed in the context of recent calculations and experimental measurements of dielectric properties of proteins.
Relativistic two-component geometric approximation of the electron-positron contribution to magnetic properties in terms of Breit–Pauli spinors
Authors: Zaccari Daniel , Melo Juan I. , Ruiz de Azúa Martín C. , Giribet Claudia G.
Published: February 2009

An alternative approach for the calculation of the electron-positron (e-p) contribution to magnetic properties based on two-component Breit–Pauli spinors is presented. In it, the elimination of the small component scheme is applied to the inverse propagator matrix of e-p pairs. The effect of the positronic manifold is expressed as an operator acting on Breit–Pauli spinors. The operator form thus obtained sums up the relativistic correction as a geometric series and as a result a totally different behavior in the vicinity of a nucleus is obtained as compared to the one of the linear response approximation. This feature has deep influence in numerical values of the e-p contribution to the nuclear magnetic shielding of heavy atoms. Numerical calculations carried out for Kr, Xe, and I show that with this approach, the e-p contributions to this property are in good agreement with those of four-component methods.
Setup of a new Brillouin light scattering apparatus with submicrometric lateral resolution and its application to the study of spin modes in nanomagnets
Authors: Gubbiotti Gianluca , Carlotti Giovanni , Madami Marco , Tacchi Silvia , Vavassori Paolo , Socino Giovanni
Published: February 2009

A new microfocused Brillouin light scattering (BLS) apparatus has been setup using a microscope objective with large numerical aperture and achieving a submicrometric lateral resolution, as inferred by reflectivity measurements taken on a set of calibration arrays consisting of Al stripes with different spacings. The micro-BLS apparatus has been then used to investigate the magnetic normal modes of elliptical Permalloy nanorings. The superiority of micro-BLS over conventional BLS measurements in the detection of stationary modes, especially those localized close to the edges of the nanoring where the internal field is highly nonhomogeneous, is demonstrated. A satisfactory interpretation of the measured spectra in terms of dynamical magnetization distribution inside the rings was achieved by a comparison with the output of dynamical micromagnetic simulations.
Numerical modeling of the splitting of magnetic droplets by multiphase lattice Boltzmann equation
Authors: Clime L. , Brassard D. , Veres T.
Published: February 2009

A multiphase lattice Boltzmann numerical model driven by an isothermal interaction potential is applied for the splitting of magnetic droplets in electrowetting-on-dielectric devices. A hydrophilic magnetic plug is considered inside the liquid droplet and successive uniform force fields are applied in order to split this droplet. The numerical results are compared with experiments on water droplets containing plugs of superparamagnetic beads and good agreement is obtained.
Bulk nanocrystalline Sm(Co1−xFex)z with z up to 14.7% and 35% Co–Fe phase and the effect of fluorine inclusion
Authors: Chen C. H. , Higgins A. K. , Huang M. Q. , Horwath J. C. , Shen Y. , Liu S.
Published: February 2009

This paper reports the effort for searching new compounds and exploring feasible techniques that can make nanocomposite magnets. Bulk nanocrystalline magnets were made using mechanical alloying and hot compaction, whose compositions were Sm(Co1−xFex)z and Sm[(Co1−xFex)1−yFy]z with z=5.6–4.7, x=0–0.575, and y=0–0.08. For isotropic Sm(Co0.834Fe0.167)z series, the remanence Br increases from 6 to 9.1 kG as z increases from 5.6 to 14.7, and the energy product (BH)maxvalues range from 3 to 13.8 MGOe. Although the coercivity Hci decreased from 12 kOe at z=6 to 3.3 kOe at z=14.7, it is noticeably good for the material with up to 35% of soft phase, showing evidence of exhange ecoupling. Magnetic properties of of Sm(Co1−xFex)1−yFy)z series indicate some texture forming for y=0.04 and z<7.6. TEM and SEM /EDS analyses show (2:17) hard phase and Fe–Co soft phase coexisting in the specimens with z>8.5.
Magnetic field amplifier employing high-Tc bulk superconductor
Authors: Choi Seyong , Kiyoshi Tsukasa , Matsumoto Shinji
Published: February 2009

We propose a new device built from a bulk superconductor to enhance the magnetic flux density within a high-field superconducting magnet. The high-temperature superconductor (HTS) bulk application, named the magnetic field amplifier, was constructed from four pieces of Gd–Ba–Cu–O superconductor. The field amplifier has a unique configuration of the bulk superconductor, which suppresses the current on the periphery of the bulk induced by external field variation. We experimentally demonstrated that the field was effectively amplified at the center of the HTS bulk device. By increasing the background field from 12 to 13 T in field-cooling mode, a magnetic flux density of 14.76 T was obtained at the center of the amplifier. The observed multiplication factor was 2.76, corresponding to external field variation. A configuration to further improve efficiency and reduce size is also presented.
Magnetic flux oscillations in partially irradiated Bi2Sr2CaCu2O8+δ crystals
Authors: Barness D. , Sinvani M. , Shaulov A. , Trautmann C. , Tamegai T. , Yeshurun Y.
Published: February 2009

We report on generation of spatiotemporal oscillations of magnetic flux in a Bi2Sr2CaCu2O8+δ crystal irradiated in part with 2.2 GeV Au ions. Flux oscillations are spontaneously excited after exposing the sample to a steady magnetic field near the order-disorder vortex phase transition line. The oscillations originate at the border between the irradiated and nonirradiated parts of the sample and propagate into the nonirradiated region toward the sample edge. Previously reported flux oscillations were observed in the vicinity of undefined defects in as grown Bi2Sr2CaCu2O8+δ crystals. Observation of spontaneous oscillations in partially irradiated samples present the first attempt to generate such oscillations in a controlled manner.
Normal modes for large molecules with arbitrary link constraints in the mobile block Hessian approach
Authors: Ghysels A. , Van Neck D. , Brooks B. R. , Van Speybroeck V. , Waroquier M.
Published: February 2009

In a previous paper [Ghysels et al., J. Chem. Phys. 126, 224102 (2007)] the mobile block Hessian (MBH) approach was presented. The method was designed to accurately compute vibrational modes of partially optimized molecular structures. The key concept was the introduction of several blocks of atoms, which can move as rigid bodies with respect to a local, fully optimized subsystem. The choice of the blocks was restricted in the sense that none of them could be connected, and also linear blocks were not taken into consideration. In this paper an extended version of the MBH method is presented that is generally applicable and allows blocks to be adjoined by one or two common atoms. This extension to all possible block partitions of the molecule provides a structural flexibility varying from very rigid to extremely relaxed. The general MBH method is very well suited to study selected normal modes of large macromolecules (such as proteins and polymers) because the number of degrees of freedom can be greatly reduced while still keeping the essential motions of the molecular system. The reduction in the number of degrees of freedom due to the block linkages is imposed here directly using a constraint method, in contrast to restraint methods where stiff harmonic couplings are introduced to restrain the relative motion of the blocks. The computational cost of this constraint method is less than that of an implementation using a restraint method. This is illustrated for the α-helix conformation of an alanine-20-polypeptide.
High volume confinement in two-photon total-internal-reflection fluorescence correlation spectroscopy
Authors: Ivanov D. , Shcheslavskiy V. , Märki I. , Leutenegger M. , Lasser T.
Published: February 2009

We report results on two-photon total-internal-reflection fluorescence correlation spectroscopy with radially polarized light. The combination of liquid crystal spatial light modulator, providing radial polarization with ultrafast laser (picosecond Nd:GdVO4 laser), allowed us to take the advantage of nonlinear optical contrast mechanisms to suppress the side-lobe energy specific for radial polarization and reduce the effective excited volume twice compared to one-photon evanescent wave excitation in fluorescence correlation spectroscopy.
Efficient hierarchical Liouville space propagator to quantum dissipative dynamics
Authors: Shi Qiang , Chen Liping , Nan Guangjun , Xu Rui-Xue , Yan YiJing
Published: February 2009

We propose an efficient method to propagate the hierarchical quantum master equations based on a reformulation of the original formalism and the incorporation of a filtering algorithm that automatically truncates the hierarchy with a preselected tolerance. The new method is applied to calculate electron transfer dynamics in a spin-boson model and the absorption spectra of an excitonic dimmer. The proposed method significantly reduces the number of auxiliary density operators used in the hierarchical equation approach and thus provides an efficient way capable of studying real time dynamics of non-Markovian quantum dissipative systems in strong system-bath coupling and low temperature regimes.
Positron transport: The plasma-gas interface
Authors: Marler J. P. , Petrović Z. Lj. , Banković A. , Dujko S. , Šuvakov M. , Malović G. , Buckman S. J.
Published: February 2009

Motivated by an increasing number of applications, new techniques in the analysis of electron transport have been developed over the past 30 years or so, but similar methods had yet to be applied to positrons. Recently, an in-depth look at positron transport in pure argon gas has been performed using a recently established comprehensive set of cross sections and well-established Monte Carlo simulations. The key novelty as compared to electron transport is the effect of positronium formation which changes the number of particles and has a strong energy dependence. This coupled with spatial separation by energy of the positron swarm leads to counterintuitive behavior of some of the transport coefficients. Finally new results in how the presence of an applied magnetic field affects the transport coefficients are presented.
Quantum molecular lensing of femtosecond laser optical/plasma filaments
Authors: Varma S. , Chen Y.-H. , Milchberg H. M.
Published: February 2009

The long-range filamentary propagation of intense femtosecond pulses in atmosphere has been observed for the first time to be strongly effected by quantum rotational wave packets. A two-pulse experiment shows that a filamenting probe pulse can be steered and trapped in or destroyed by the rotational alignment wake following a pump filament.
White light emission from silicon oxycarbide films prepared by using atmospheric pressure microplasma jet
Authors: Ding Yi , Shirai Hajime
Published: February 2009

An atmospheric pressure microplasma jet was employed as a deposition tool to fabricate silicon oxycarbide films from tetraethoxysilane-argon (Ar) mixture gas at room temperature. Resultant films exhibit intense visible emission under a 325 nm excitation which appears white to naked eyes in the range from ∼1.75 to ∼3.5 eV at room temperature. The origin of photoluminescence is attributed to the electron-hole pair recombination through neutral oxygen vacancies (NOVs) in the film. The density of NOV defects was found in the range from 3.48×1015 to 2.23×1016 cm−3. The photoluminescence quantum efficiencies were estimated to be 1.48%–4.15%. Present experiment results demonstrate that the silicon oxycarbide films prepared by using atmospheric pressure microplasma jet would be a competitive candidate for the development of white light emission devices.
Great enhancement of pyroelectric properties for Ba0.65Sr0.35TiO3 films on Pt–Si substrates by inserting a self-buffered layer
Authors: Wu C. G. , Li Y. R. , Zhu J. , Liu X. Z. , Zhang W. L.
Published: February 2009

( 100 ) -Ba 0.65 Sr 0.35 TiO 3 (BST) films were deposited on Pt/Ti/SiO2/Si substrates using a low-temperature self-buffered layer. X-ray diffraction and atomic force microscope investigations show that the microstructure of BST films strongly depends on surface morphology of annealed self-buffered layer. The mechanism of nucleus formation and the growth initiation of BST films on self-buffered layers were proposed. It was found that the pyroelectric properties of BST films can be greatly enhanced. The pyroelectric coefficient and material merit figure of (100)-BST films are 1.16×104 μC m−2 K−1 and 2.18×10−4 Pa−1/2, respectively. The detectivity of 9.4×107 cm Hz1/2 W−1 was obtained in the (100)-BST film capacitors thermally isolated by 500 nm SiO2 films.
Crystallography of self-assembled DySi2 nanowires on a Si substrate
Authors: Qiu Dong , Zhang Ming-Xing , Kelly Patrick M.
Published: February 2009

A recently developed crystallographic model, edge-to-edge matching, has been used to interpret the crystallographic features of self-assembled DySi2 nanowires on Si substrates. All of the observed orientation relationships (ORs) and interface orientations of the DySi2 on Si(111), (001), and (110) were predicted by one criterion. The calculated results are fully consistent with the previous high-resolution transmission electron microscopy observations. The preference for each OR and interface was discussed in terms of the competition between thermodynamics and kinetic factors. This model can also be used in other epitaxy systems and has strong potential for future nanostructure design.
Strong and stable photoluminescence from the semiconducting inner tubes within double walled carbon nanotubes
Authors: Shimamoto Daisuke , Muramatsu Hiroyuki , Hayashi Takuya , Kim Yoong Ahm , Endo Morinobu , Park Jin Sung , Saito Riichiro , Terrones Mauricio , Dresselhaus Mildred S.
Published: February 2009

We examined the optical features of single wall carbon nanotubes (SWNTs) and the inner tubes within double walled carbon nanotubes (DWNTs) having the same (n,m) chirality. The brighter and more stable photoluminescence signals as well as the larger absorbance were observed for the semiconducting inner tubes within DWNTs and not for SWNTs. The outer layers of DWNTs maintain the high structural integrity of the inner tubes during both oxidative purification and strong sonication steps and are responsible in increasing the dielectric screening (due to weaker Coulomb interaction); thus leading to a redshift of the E11S and E22S excitonic transitions.
Unified explanation of the fluorescence decay and blinking characteristics of semiconductor nanocrystals
Authors: Tachiya M. , Seki Kazuhiko
Published: February 2009

Recently power law dynamics was observed in the fluorescence decay from semiconductor nanocrystals and a model was proposed and analyzed on the basis the of Monte Carlo simulation to clarify the relation between the power law fluorescence decay and the power law blinking. However, analysis of the model on the basis of the Monte Carlo simulation is not decisive. In this paper we present the analytical solution of the model. The analytical result is used to prove rigorously that the exponent of the power law blinking and that of the power law fluorescence decay are the same.
Dynamic ferroelectric hysteresis scaling of BaTiO3 single crystals
Authors: Wongdamnern N. , Ngamjarurojana A. , Laosiritaworn Y. , Ananta S. , Yimnirun R.
Published: February 2009

The scaling behavior of the dynamic hysteresis of ferroelectric BaTiO3 single crystals was investigated. Two sets of the scaling relation of hysteresis area ⟨A⟩ against frequency f and field amplitude E0 were clearly established. Above the coercive field, the scaling took a form of ⟨A⟩∝f−0.195E00.950. On the other hand, the scaling in the form of ⟨A⟩∝f1.667E0−2.804E04.157 was obtained under subcoercive field condition. While these scaling relations were generally comparable to previously reported ones, it was found that the f and E0 exponents depended on E0 and f, respectively, which was in contrast to the prior theoretical prediction and experimental investigations.
A low-temperature spin-polarized scanning tunneling microscope operating in a fully rotatable magnetic field
Authors: Meckler S. , Gyamfi M. , Pietzsch O. , Wiesendanger R.
Published: February 2009

A new scanning tunneling microscope for spin-polarized experiments has been developed. The microscope is operated at 4.7 K in a superconducting triple axis vector magnet providing the possibility for measurements depending on the direction of the magnetic field. In single axis mode the maximum field is 5 T perpendicular to the sample plane and 1.3 T in the sample plane, respectively. In cooperative mode fields are limited to 3.5 T perpendicular and 1 T in plane. The microscope is operated in an ultrahigh vacuum system providing optimized conditions for the self-assembled growth of magnetic structures at the atomic scale. The available temperature during growth ranges from 10 up to 1100 K. The performance of the new instrument is illustrated by spin-polarized measurements on 1.6 atomic layers Fe/W(110). It is demonstrated that the magnetization direction of ferromagnetic Fe and Gd tips can be adjusted using the external magnetic field. Atomic resolution is demonstrated by imaging an Fe monolayer on Ru(0001).
Current-voltage characteristics of poly(3-hexylthiophene) diodes at room temperature
Authors: Giulianini Michele , Waclawik Eric R. , Bell John M. , Motta Nunzio
Published: February 2009

We report on the analysis of current-voltage characteristics of regioregular poly(3-hexylthiophene) diodes. Experimental curves were fitted to two models, to take into account at low-moderate electric fields Schottky behavior mixed with space charge limited current (SCLC) regime and, at higher fields, trap-free SCLC. The results provide a description of IV curves over five decades, along with the determination of zero field and effective mobility and the field dependence prefactor. Forward and reverse IV measurements highlighted the presence of shallow and deep localized states inside the band gap. The latter enhance the current over time and have been modeled as an inductorlike element.
Optimized efficiency and angular emission characteristics of white top-emitting organic electroluminescent diodes
Authors: Thomschke Michael , Nitsche Robert , Furno Mauro , Leo Karl
Published: February 2009

The concept of an additional capping layer, which is deposited onto the semitransparent top contact, is applied to minimize microcavity effects for white light emission from top-emitting organic light emitting devices (OLEDs). The influence on the optical properties of such devices with silver as top electrode material is discussed using an analytical method and numerical simulations. The results of the theoretical findings are experimentally verified for inverted top emitting devices on opaque substrates, showing broad spectral bandwidth and angle-independent color coordinates.
Stabilization of lithium superionic conduction phase and enhancement of conductivity of LiBH4 by LiCl addition
Authors: Matsuo Motoaki , Takamura Hitoshi , Maekawa Hideki , Li Hai-Wen , Orimo Shin-ichi
Published: February 2009

LiBH 4 exhibits lithium superionic conduction accompanied by structural transition at around 390 K. Addition of LiCl to LiBH4 drastically affects both the transition and electrical conductivity: Transition from low-temperature (LT) to high-temperature (HT) phases in LiBH4 is observed at 370 K upon heating and the HT phase can be retained at 350–330 K upon cooling. Further, the conductivity in the LT phase is more than one or two orders of magnitude higher than that of pure LiBH4. These properties could be attributed to the dissolution of LiCl into LiBH4, suggested by in situ x-ray diffraction measurement.