bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of a sustained inflation on regional distribution of gas and perfluorocarbon during partial liquid ventilation
Authors: Morris Kevin , Cox Peter , Frndova Helena , Holowka Stephanie , Babyn Paul
Published: January 2007

Objective

To study the effect of a sustained inflation (SI) maneuver on the regional distribution of gas and perfluorocarbon (PFC) during partial liquid ventilation (PLV) in normal pigs using computerized densitometry.

Study Design

Observational study.

Setting

Animal research laboratory.

Participants

Three healthy anaesthetized pigs.

Interventions

Partial liquid ventilation, lung recruitment, CT densitometry.

Methodology

Lungs were filled with PFC to “liquid functional residual capacity (FRC)” (35–41 ml/kg) and CT images were recorded at a series of predetermined airway pressure levels (0, 20, 30, 40 cm H2O) both before and after SI to an airway pressure of 40 cm H2O for 30 sec. Anterior, middle, and posterior regions from upper (apical lung) to lower (basal lung) CT slices were analyzed at each pressure level for Hounsfield units to describe the relative distribution of gas and PFC before and after SI. Using an occlusion technique true gas volume above FRC was determined at each pressure level, before and after SI, and a pressure‐volume (gas) envelope determined for each animal.

Results

At low airway pressures (<20 cm H2O) gas was distributed predominantly to the anterior (non‐dependent) part of the lung and PFC predominantly to the posterior (dependent) lung. Gas and liquid were more uniformly distributed throughout the lung at airway pressures >20 cm H2O. Generation of a pressure‐volume (gas) envelope for each animal demonstrated an increase in total gas volume above FRC at each pressure level following recruitment of the lung with SI. However, marked regional differences were evident with the greatest effects of SI seen at higher airway pressures in posterior and basal regions.

Conclusion

The healthy PFC filled lung demonstrates an increase in total gas volume following SI. CT densitometry suggests marked heterogeneity of gas/PFC distribution between different regions of lung and heterogeneity of response to SI. Pediatr Pulmonol. 2007; 42:204–209. © 2007 Wiley‐Liss, Inc.
The relationship of clinical and inflammatory markers to outcome in stable patients with cystic fibrosis
Authors: Downey Damian G. , Martin S. Lorraine , Dempster Martin , Moore John E. , Keogan Mary T. , Starcher Barry , Edgar Julia , Bilton Diana , Elborn J. Stuart
Published: January 2007

Decreased survival in patients with cystic fibrosis has been related to FEV1, BMI, and infection with Burkholderia cepacia complex (BCC). We have assessed the relationship of blood, sputum, and urine inflammatory markers to lung function, BMI, colonization with B cenocepacia (Bc), and patient survival. Thirty‐nine stable cystic fibrosis (CF) patients (10 with Bc) were enrolled in a study to determine the effect of alpha‐1‐antitrypsin on airways inflammation. Pre‐treatment measurements were used in this study. Demographics, sputum microbiology, heart rate, oxygen saturation, lung function were recorded. Blood samples were obtained for white blood count (WBC), C‐Reactive Protein (CRP), and plasma neutrophil elastase/AAT complexes (pNEC). Neutrophil elastase (NE), neutrophil elastase/AAT complexes (sNEC), interleukin‐8 (IL‐8), TNF‐receptor 1 (sTNFr), and myeloperoxidase (MPO) were measured in sputum and urinary desmosine concentration determined. Patients with Bc had significantly higher levels of pNEC, 332 ± 91.4 ng/ml (mean ± SEM) versus 106 ± 18.2 ng/ml (P = 0.0005) and sNEC, 369 ± 76.6 ng/ml versus 197 ± 36.0 ng/ml compared to those who were not. Five deaths were reported at the end of 1 year, (four with Bc) (P = 0.011). Patients who subsequently died had significantly lower lung function FEV1, 1.2 ± 0.2 L versus 2.0 ± 0.1 L (P = 0.03) and FVC, 2 ± 0.3 L versus 3.1 ± 0.2 L (P = 0.01), compared to those that survived. There was significantly higher NE activity, 3.6 ± 1.6 U/ml versus 1.5 ± 0.6 U/ml (P = 0.03), pNEC, 274 ± 99 ng/ml versus 142 ± 30 ng/ml (P = 0.05), MPO, 163 ± 62 mcg/ml versus 54 ± 6.9 mcg/ml (P = 0.03), and urinary desmosines 108 ± 19.9 pM/mg creatinine versus 51.1 ± 3.3 pM/mg creatinine (P = 0.001), in those patients who subsequently died compared to those that survived. These data suggest there is increased neutrophil degranulation in patients infected with Bc and these patients have a poor outcome. Pediatr Pulmonol. 2007; 42:216–220. © 2007 Wiley‐Liss, Inc.
Incidence and outcome of scoliosis in children with pleural infection
Authors: Mukherjee S. , Langroudi B. , Rosenthal M. , Balfour‐Lynn I.M.
Published: January 2007

Aims

To ascertain the incidence and outcome of secondary scoliosis associated with parapneumonic effusions/empyema.

Methods

Retrospective review of case notes of children with pleural effusions over a 3‐year period. Review of digitalized erect chest radiographs by two observers with serial measurements of Cobb angles. Scoliosis defined as lateral curvature of the spine ≥10°.

Results

Of 122 children (median age 4.3 years), 103 (84%) required chest drains of whom 83/103 (81%) received urokinase; 5 (4%) required surgical decortication. On admission, 56 (46%) had a scoliosis, 68 (62%) on the 2nd radiograph, and 68 (59%) at discharge; overall 87 (71%) had a scoliosis at some stage. In all cases, there was a single thoracic curve with the direction towards the side of the effusion. There was no association between scoliosis and size or type of effusion, nor inflammatory markers. There was a statistically significant but small effect from duration of illness prior to admission. At follow‐up, 6 (5%) had a mild residual scoliosis but all subsequently resolved. Intraobserver variability for measurement of Cobb angles was ±4.6° and interobserver variability was ±5.8°.

Conclusions

Scoliosis was common but always resolved so therapy is unnecessary; follow up is recommended to exclude coincidental idiopathic scoliosis. Pediatr Pulmonol. 2007; 42:221–224. © 2007 Wiley‐Liss, Inc.
Unilateral lung agenesis—detrimental roles of surrounding vessels
Authors: Chou An‐Kou , Huang Shu‐Chien , Chen Shyh‐Jye , Huang Pei‐Ming , Wang Jou‐Kou , Wu Mei‐Hwan , Chen Yih‐Sharng , Chang Chung‐I , Chiu Ing‐Sh , Wu En‐Ting
Published: January 2007

Unilateral lung agenesis is a rare congenital defect and could be associated with multiple abnormalities. The patients usually have poor long‐term outcomes especially in those with right lung agenesis. We reviewed the 10‐year experience in our hospital to describe special clinical features and try to delineate the causes of poor outcomes. From 1995 to 2005, 14 patients less than 18 years of age with unilateral lung agenesis (4 with left agenesis, 10 with right agenesis) were enrolled. Medical records reviewed included diagnosis, presentation, chromosome anomalies, cardiovascular anomalies and interventions, outcomes. We found that the mechanisms of severe airway disease in right lung agenesis included (1) trachea compression by the aortic arch, (2) the presence of “pseudo–ring‐sling complex,” (3) distended pulmonary artery due to left to right shunt which impinged the only bronchus, and finally (4) the persistent LSVC that restricts the growth of trachea. The etiologies of airway complication in left lung agenesis included anomalous aortic arch compression on trachea and the coexisting heart disease with significant left to right shunt, which impinged on the bronchus. In conclusion, unilateral lung agenesis has frequently associated airway problems due to its surrounding vessels. Satisfactory airway intervention remains challenging. This disease still requires great effort to improve patient outcomes. Pediatr Pulmonol. 2007; 42:242–248. © 2007 Wiley‐Liss, Inc.
Abiotic influences on the biomass of Vallisneria americana Michx. in the Upper Mississippi River
Authors: Kreiling Rebecca M. , Yin Yao , Gerber D. Timothy
Published: January 2007

American wildcelery, Vallisneria americana Michx. is an ecologically important component of aquatic communities in the Upper Mississippi River (UMR). We conducted a study in 2002 to determine the association of several abiotic factors on the vegetative growth of Vallisneria in Navigation Pool 8 (Pool 8) of the UMR. We measured turbidity, percent light absorbance, surface water ammonium, surface water nitrate, current velocity, conductivity, pH and water depth throughout one growing season at 56 stratified sites based on where Vallisneria occurred in previous years. Sediment and aboveground biomass samples were collected during peak growth. Sediment was analysed for organic content, particle size, pore water nitrate and pore water ammonium. Vallisneria biomass samples were dried to constant mass. Because some sites were without water for much of the growing season, only data from 52 sites were reported. Biomass was associated with depth, percent light absorbance, turbidity and wind fetch. Vallisneria was abundant in the depth range of 0.55 to 1.03 m, in areas receiving at least 38% of surface light and in areas exposed to greater wind fetch (>2000 m). Our results suggest that the primary abiotic variable associated with Vallisneria americana in the UMR is light, not nutrients. Published in 2007 John Wiley & Sons, Ltd.
Defining and developing measures of lean production
Authors: Shah Rachna , Ward Peter T.
Published: January 2007

Our research addresses the confusion and inconsistency associated with “lean production.” We attempt to clarify the semantic confusion surrounding lean production by conducting an extensive literature review using a historical evolutionary perspective in tracing its main components. We identify a key set of measurement items by charting the linkages between measurement instruments that have been used to measure its various components from the past literature, and using a rigorous, two‐stage empirical method and data from a large set of manufacturing firms, we narrow the list of items selected to represent lean production to 48 items, empirically identifying 10 underlying components. In doing so, we map the operational space corresponding to conceptual space surrounding lean production. Configuration theory provides the theoretical underpinnings and helps to explain the synergistic relationships among its underlying components.
A programme for teaching social skills to socially inept adolescents: description and evaluation
Authors: Lindsay William R. , Symons Ruth S. , Sweet Tony
Published: January 2007

The authors have adapted the techniques of social skills training to suit group work with adolescents. This paper presents a programme which enables working with teenagers on areas such as initiating conversations, joining conversation groups, assertion skills, dealing with authority figures, interviewing skills, keeping out of trouble and heterosexual interaction. Although the programme is divided into sections it is not time limited and each section is worked through until both therapists and patients feel comfortable with the behaviours involved. Some outcome data is presented which indicates that the programme is successful in producing improvements in rated social skill, self reports of social behaviour and social aspects of personality. We find the programme useful not only because it produces improvements in social ability but also because the adolescents themselves seem to regard the treatment as both practical and supportive.
The conditioning treatment of bed‐wetting in secondary school aged children
Authors: Brooksbank Donald J.
Published: January 2007

A study is reported of 25 cases aged 11 to 15 years, referred to a special clinic and treated on a conditioning programme using the auditory alarm technique followed by a period of ‘over‐learning”, found to be effective in reducing relapse rates. The management is described in detail and potential problems for the individual are considered as well as the results obtained for the group as a whole.
Anorexia nervosa—A clinical study of ten patients and their family systems
Authors: Norris D.L. , Jones E.
Published: January 2007

An in‐depth clinical evaluation of ten anorexia nervosa patients and their families is reported. Structural and process pathology found in common within all ten family systems is analysed according to “systems” criteria. A model is constructed in which anorexia nervosa is seen as a compromise solution for three primary, conflicting pathological processes which are identified as “the idealised family myth”, “an enmeshed family dyad” and “a process barrier within the patient”. It is the view of the authors that this model may have significant implications both for diagnosis and therapy.
Reactions to a psychiatric service for adolescents: a survey of professional referrers
Authors: Raven Faith
Published: January 2007

An investigation to discover what factors underlay the referrers' overall reaction to the service provided by an adolescent unit is described. In particular, the part played by unfamiliar features of the unit's admission procedure is explored.

The survey covers 102 referrers who could be traced after their contact with the unit.

The referrer's satisfaction correlated with perceived improvements in the adolescents and the increased degree of contact with the unit and with the involvement of the referrer in decisions about the patient.
Life cycles in transition: a family systems perspective on counselling the college student
Authors: Fulmer R.H. , Medalie J. , Lord D.A.
Published: January 2007

Many of the psychological problems of college students can be viewed from the perspective of family systems theory in addition to the intrapsychic and interpersonal viewpoints. We have attempted to detail the way in which the college student's leaving home affects his family. We have also shown how the current situation of the other family members (their own developmental stages, their reaction to their child's departure and their ongoing relationships with each other) affects the adaptation and development of the college student. We have suggested that the way in which mothers and fathers are passing through their respective stages of adult development contribute substantially to the student's adjustment to his new context. A case example illustrating the addition of this systemic approach has been presented. Finally, the implications of a systems viewpoint for individual treatment have been presented, both in a case example and by the description of specific techniques.
The family and adolescence: a conceptual and experimental approach
Authors: Shulman S. , Klein M.M.
Published: January 2007

Adolescence represents developmental demands that require one to be able to act independently of the family. Conceiving adolescence as a process of separation means that the entire family has to deal with the demands for separation. The optimal family helps its adolescent to reach this goal. There are types of families that counteract the process of separation, either by preventing the adolescent from leaving the family system or by pushing for premature independence. In this research it was found that families having an adolescent referred for treatment belonged to one of these family types. These pathological family systems were characterized in the study according to Reiss's and Wynne's theories.
Representations of the future among Senegalese secondary school students
Authors: D'Hondt W. , Vandewiele M.
Published: January 2007

This study investigated future perspectives of young Senegalese by administering a questionnaire to 1044 secondary school students (282 girls and 762 boys, age range 11–22 years). This amounted to only two questions: (1) how do you imagine yourself in 20 years' time and (2) how do you figure out the world in the year 2000?

Concerning their own future, the students' main preoccupation was about their role as a father/mother of a family and their assistance to their parents. A majority nourished great professional ambitions and paid most particular attention to the material aspects of their careers. Over half of them expected a definite change in the evolution of their personality. As to the world's future, they were slightly more pessimistic than optimistic (boys and older students above all). A portion of the sample expressed fear of war and concern over the moral degradation of the times while some others still believed in peace and a better world.
Antecedents of affective role‐taking behaviour: adolescent perceptions of parental socialization styles*
Authors: Adams Gerald R. , Jones Randy M. , Schvaneveldt Jay D. , Jenson Glen O.
Published: January 2007

Previous research has suggested early parental socialization experiences may be associated with adolescents' affective role‐taking development. To test this assumption adolescent males' (n=58) and females' (n=57) empathy and social sensitivity behaviours were correlated with perceived paternal and maternal childrearing behaviours. Paternal support and rejection‐control and maternal support and physical affection were found to be significantly correlated with empathy and social sensitivity roletaking in males. No relationship was observed between parental socialization styles and female adolescents' empathy and social sensitivity scores. Females scored, on the average, higher on both role‐making measures than did males.
Group work with adolescents in a girls' conprehensive school
Authors: Rushton Andrée
Published: January 2007

This is a descriptive study of groups run by social workers and youth workers for fourth‐year girls in a comprehensive school. For the last six years, the project, organized by the school counsellor, has involved all the girls in turn in small discussion groups, lasting six weeks. This paper presents the results of a survey of the leaders' and members' perceptions of the groups during one academic year. It describes the aims of the project, broadly to provide the girls with an opportunity to acquire the skills necessary to effective group discussion on topics of their choice and explains the aims and method of the research. The results show that the leaders consider their aims are met to some extent, but a number of problems are identified which centre on the willingness of the girls to participate. The girls' responses show a very mixed reaction to the project, but clearly some are able to make use of it.
Communication therapy
Authors: Lucas Tina
Published: January 2007

This paper describes by method of working with delinquent adolescent boys in a psychiatric Borstal who have been referred with problems concerning communication. I concentrate here on work with boys who stammer, and give a case history of one such boy.
Similarity and attraction: the relationship between personality, beliefs, skills, needs and friendship choice
Authors: Henderson Monika , Furnham Adrian
Published: January 2007

Eighty‐six female students in a single lecture group were asked to completesix commonly used self‐report scales. Three months later they were asked to nominate their friends, close friends or acquaintances from the class. Another three months later they were asked to predict their own scores on each of the self‐report scales plus those of a close friend or well known acquaintance in the class. Scores on each measure were correlated across categories of friendship nomination, using both actual and predicted scores. Results show that measures of needs, social skills and beliefs were more highly correlated between individuals nominating each other than personality measures when examining actual scores. Predicted scores showed less consistency. Results were discussed in relation to the similarity‐attraction hypothesis of friendship formation.
Adolescents, violence and crime*
Authors: Williams Arthur Hyatt
Published: January 2007

This article is concerned with automatic, unconscious reality testingmechanisms—a series of steps whereby a mini mourning process related to aggressive or delinquent fantasies is undertaken that leaves the self clear without persecutory feelings, and without the delinquent urges protesting against the civilized restrictions.
Declarative modelling in the ecological and environmental sciences
Authors: Muetzelfeldt Robert
Published: January 2007

Most simulation models in ecological and environmental research are implemented as computer programs in a conventional programming language. This brief paper argues for a radically different approach, based on the representation of the model structure, relationships and equations in a declarative format (e.g. XML). Simulation code can then be generated from this, but in addition the model can be displayed and processed in a wide range of useful ways, greatly increasing the efficiency and effectiveness of the modelling process.
Environmental modelling and Web 2.0 - using Connotea to share XML-represented information
Authors: Muetzelfeldt Robert
Published: January 2007

Much academic information can be represented in a structured way and published on the web as XML documents. Such information can then be displayed in a wide variety of ways, using different XSLT stylesheets. This presentation presents MultiGuise, a Web application which allows any of several XML documents to be displayed using any of several stylesheets. Both the documents and the stylesheets are bookmarked in Connotea, from where MultiGuise retrieves them using a special tag. This approach means that anyone can add documents and stylesheets, simply by bookmarking them in Connotea.The approach is illustrated primarily with environmental models represented in XML, but also with examples from SBML (Systems Biology Markup Language) and philosophical arguments marked up in XML.
Globular structures of a helix-coil copolymer: Self-consistent treatment
Authors: Nowak C. , Rostiashvili V. G. , Vilgis T. A.
Published: January 2007

A self-consistent-field theory was developed in the grand canonical ensemble formulation to study transitions in a helix-coil multiblock globule. Helical and coil parts are treated as stiff rods and self-avoiding walks of variable lengths correspondingly. The resulting field theory takes, in addition to the conventional Zimm-Bragg, [J. Chem. Phys. 31, 526 (1959)] parameters, also three-dimensional interaction terms into account. The appropriate differential equations which determine the self-consistent fields were solved numerically with finite element method. Three different phase states are found: open chain, amorphous globule, and nematic liquid-crystalline (LC) globule. The LC-globule formation is driven by the interplay between the hydrophobic helical segment attraction and the anisotropic globule surface energy of an entropic nature. The full phase diagram of the helix-coil copolymer was calculated and thoroughly discussed. The suggested theory shows a clear interplay between secondary and tertiary structures in globular homopolypeptides.
Effect of screw dislocation density on optical properties in n-type wurtzite GaN
Authors: You Jeong Ho , Johnson H. T.
Published: January 2007

The effect of open-core screw dislocations on photoluminescence in n-doped wurtzite GaN epilayer is studied computationally and compared with experimental data. A k•p Hamiltonian calculation domain is set up to contain a dipole of open-core screw dislocations, and its size is varied according to the desired dislocation density. Using the finite element method, energy levels and wave functions for conduction and valence states are determined in three-dimensional real space; the emission spectrum is then evaluated. The void associated with the dislocation core and the deformation potential due to the strain surrounding the core perturb the density of states and reduce the photoluminescence (PL) spectrum intensity accordingly. For dislocation densities below a transition density of around 108cm−2, the deformation potential effect dominates in reducing the PL intensity; above this dislocation density the effect of the missing material at the core dominates. The calculated photoluminescence results agree with experimental near-band edge PL intensity data well. Both the experimental and calculated PL spectra indicate a significant reduction in the optical response for a dislocation density larger than 107cm−2.
Relaxations and nano-phase-separation in ultraviscous heptanol-alkyl halide mixture
Authors: Power G. , Vij J. K. , Johari G. P.
Published: January 2007

To gain insight into the effects of liquid-liquid phase separation on molecular relaxation behavior we have studied an apparently homogeneous mixture of 5-methyl-2-hexanol and isoamylbromide by dielectric spectroscopy over a broad temperature range. It shows two relaxation regions, widely separated in frequency and temperature, with the low-frequency relaxation due to the alcohol and the high-frequency relaxation due to the halide. In the mixture, the equilibrium dielectric permittivity εs of the alcohol is 41% of the pure state at 155.7K and εs of isoamylbromide is ∼86% of the pure state at 128.7K. The difference decreases for the alcohol component with decreasing temperature and increases for the isoamylbromide component. The relaxation time τ of 5-methyl-2-hexanol in the mixture at 155.7K is over five orders of magnitude less than in the pure state, and this difference increases with decreasing temperature, but τ of isoamylbromide in the mixture is marginally higher than in the pure liquid. This shows that the mixture would have two Tg’s corresponding to its τ of 103s, with values of ∼121K for its 5-methyl-2-hexanol component and ∼108K for its isoamylbromide component. It is concluded that the mixture phase separates in submicron or nanometer-size aggregates of the alcohol in isoamylbromide, without affecting the latter’s relaxation kinetics, while its own εs and τ decrease markedly.
Initial stage of spinodal decomposition in a rigid-rod system
Authors: Green Micah J. , Brown Robert A. , Armstrong Robert C.
Published: January 2007

The initial stage of spinodal decomposition is investigated for a rigid-rod system. Spinodal decomposition proceeds through either of two mechanisms: (1) The randomly aligned rods rotate toward a common director with no inherent length scale. (2) The rods diffuse axially and segregate into regions of common alignment with a selected length scale ℓ. Previous studies on spinodal decomposition yielded radically different conclusions about which mechanism is dominant. A computational method is employed to analyze the growth rate and properties of the dominant fluctuation mode through an eigenvalue analysis of the linearized Doi diffusion equation in Fourier space. The linearized operator is discretized in Fourier mode and orientation space (k,θ,ϕ) space, and the maximum eigenvalue and corresponding eigenvector of the operator are calculated. Our analysis generalizes the results of previous studies and shows that the conflicts seen in those studies are due to differences in the diffusivities for rotational motion, motion perpendicular to the rod axis, and motion along the rod axis. For a given system density, a plot of the dominant perturbation wave number kmax as a function of the diffusivity ratios shows two separate regions corresponding to mechanisms (1) and (2). High rotational diffusivity corresponds to mechanism (1), whereas high axial diffusivity corresponds to mechanism (2). The transition between the two mechanisms depends on the ratio of diffusivities and on system density. Also, the dominant wave number increases with increasing density indicating that a deeper quench into the spinodal regime leads to a smaller characteristic length scale.
Giant magnetoimpedance in Ag-doped La0.7Sr0.3MnO3
Authors: Ghatak S. K. , Kaviraj B. , Dey T. K.
Published: January 2007

The resistive and reactive parts of the magnetoimpedance of sintered ferromagnetic samples of La0.7Sr0.3−xAgxMnO3 (x=0.05,0.25) have been measured at room temperature (<Tc) over a frequency interval from 1kHzto15MHz and in the presence of magnetic field up to 4kOe. The field dependence of relative change in resistance [ΔR∕R(0)] is small in the kilohertz region but increases strongly for higher frequency of excitation. The maximum value of [ΔR∕R(0)] at H=4kOe and for ω=15MHz is around 70%. On the contrary the corresponding change in reactance [ΔX∕X(0)] has less frequency sensitivity, and the maximum occurs at ω≈1MHz. The magnetoimpedance is negative for all frequencies. The normalized magnetoimpedance δZ as defined by [Z(H)−Z(0)]∕[Z(0)−Z(4kOe)] when plotted against scaled field H∕H1∕2 is found to be frequency independent; H1∕2 is the field where δZ is reduced to half its maximum. A phenomenological formula for magnetoimpedance, Z(H), in a ferromagnetic material, is proposed based on the Padé approximant. The formula for Z(H) predicts the scaled behavior of δZ.
Theoretical and numerical analysis of very high harmonic superconducting tunnel junction mixers
Authors: Kittara P. , Withington S. , Yassin G.
Published: January 2007

We describe a procedure for modeling the nonlinear, quantum-mechanical behavior of very high harmonic superconductor-insulator-superconductor (SIS) mixers. A typical mixer is pumped by a strong microwave source at 10–15GHz, which causes high-harmonic (20–40) currents to flow, any one of which can be used as a local oscillator to downconvert a submillimeter-wave signal to a low microwave frequency, 1–8GHz. This mode of operation is attractive for measuring the beam patterns of conventional SIS mixers, because only a single submillimeter-wave source is needed. We conducted simulations using the 20th harmonic of a 13.5GHz microwave source, downconverting a 271.4GHz signal to a 1.4GHz intermediate frequency. These simulations clearly show that linear downconversion can be achieved even for relatively high levels of rf signal power; although, care is needed when choosing the operating point. The patterns of behavior seen in the simulations are in remarkable agreement with recently published experimental results.
The comparison of the growth models of silicon nitride ultrathin films fabricated using atmospheric pressure plasma and radio frequency plasma
Authors: Nakae Mari , Hayakawa Ryoma , Yoshimura Takeshi , Fujimura Norifumi , Kunugi Shunsuke , Uehara Tsuyoshi
Published: January 2007

The reaction process model during initial nitridation of Si (111) using atmospheric pressure plasma source was constructed and it was compared to that using a radio frequency plasma source. In atmospheric pressure plasma, emission lines from the N2 second positive system were dominantly observed. By exposing the atmospheric pressure plasma to Si substrate at the temperature ranging from 25to500°C, silicon nitride films with a thickness below 1.8nm were formed. In order to study the nitridation process, the changes in the film thickness against the substrate temperature and nitridation time were systematically studied at a pressure ranging from 50to700Torr. The film thickness increases with increasing the nitridation pressure below 400Torr and it saturates above 500Torr. It was completely regardless of the substrate temperature. From the time dependence of the film thickness at various nitridation pressures, it was revealed that these experimental results were well fitted to a Langmuir-type adsorption model. In the case of nitridation using atmospheric pressure (AP) plasma, molecular species play an important role for nitridation without thermal diffusion. The difference of silicon nitride films fabricated using AP plasma and rf plasma originates from the difference in the active species.
Transport of nonequilibrium carriers in bipolar semiconductors
Authors: Gurevich Yu. G. , Velázquez-Pérez J. E. , Espejo-López G. , Volovichev I. N. , Titov O. Yu.
Published: January 2007

In this work we present results concerning the fundamental equations of charge-carrier transport in semiconductor structures. We discuss a correct modeling of the recombination terms that does not violate the charge conservation law. We obtained that under stationary conditions and equal generation rates of electrons and holes the recombination rates of both kinds of carriers must be matched. Under low excitation conditions (linear regime) the recombination rate can be expressed as a linear combination of the excess concentrations of electrons and holes, and only in very precise situations can a lifetime be defined. Explicit calculation of the charge variation was carried out within the framework of the band-to-band and Shockley-Read-Hall statistics. It is shown that the bulk space charge established on distances of the order of Debye’s length cannot influence the current-voltage characteristics of a device in a linear regime. It was also shown that metal-p-type semiconductor contacts are essentially different from those made on n-type semiconductors. The former should be considered as having a bipolar semiconductor structure and recombination cannot be neglected. The boundary conditions for the Poisson equation are presented.
Aging phenomena in ferrofluids suitable for magnetic biosensor applications
Authors: Strömberg M. , Gunnarsson K. , Valizadeh S. , Svedlindh P. , Strømme M.
Published: January 2007

Aging phenomena were investigated in three different ferrofluids containing submicron sized magnetic beads consisting of a cluster of iron oxide nanoparticles embedded in a dextrane matrix with primary amine groups on the surface (one fresh sample and one sample aged during three months) and with a plain surface (only dextrane on the surface, aged for three months), suitable for magnetic biosensor applications. The main characterization technique used was measurement of the frequency dependent complex magnetization using a superconducting quantum interference device. The experimental factors considered were the effect of ultrasonication, temperature, dc bias magnetic field, and addition of sodium dodecyl sulphate surfactant. The stability against aging was found to depend strongly on the bead surface, and the reproducibility of a refreshing procedure involving addition of surfactant in combination with ultrasonication was shown to be low. Aggregation was shown to be strongly affected by the presence of even a small bias magnetic field. Applying a dc bias field caused the formation of more or less stable chainlike aggregates with various lengths.
The temperature dependence of the isothermal bulk modulus at 1bar pressure
Authors: Garai J. , Laugier A.
Published: January 2007

It is well established that the product of the volume coefficient of thermal expansion and the bulk modulus is nearly constant at temperatures higher than the Debye temperature. Using this approximation allows predicting the values of the bulk modulus. The derived analytical solution for the temperature dependence of the isothermal bulk modulus has been applied to ten substances. The good correlations to the experiments indicate that the expression may be useful for substances for which bulk modulus data are lacking.
Correlations among size, defects, and photoluminescence in ZnO nanoparticles
Authors: Xiong Gang , Pal U. , Serrano J. Garcia
Published: January 2007

We studied the correlations among size, defects, and photoluminescence emissions in ZnO nanoparticles of sizes ranging from 25 to 73 nm. The impurities and defects were characterized by Fourier-transform infrared spectroscopy and Raman spectroscopy. Particles of larger size revealed fewer surface impurities and enhanced E2 mode of hexagonal ZnO crystals, while the oxygen vacancy centers did not vary significantly with particle size. A simultaneous increase of excitonic luminescence and defect luminescence intensities with the increase of particle size is shown, indicating both emissions are subjected to nonradiative quenching by near surface defects. The study on the size-dependent green luminescence in our samples suggests that the emission might be a bulk property instead of having a surface origin in nanostructured ZnO. Two different radiative recombination processes are involved in the excitonic emission of ZnO. While the slow decay component (370 ps) did not depend on particle size, the fast component varied from 56 to 96 ps. We attribute the slow component to free exciton recombination, while the fast component is attributed to near surface exciton recombination.
Effect of surface wettability on liquid density, structure, and diffusion near a solid surface
Authors: Thomas J. A. , McGaughey A. J. H.
Published: January 2007

Molecular dynamics and Langevin dynamics simulations are used to elucidate the behavior of liquid atoms near a solid boundary. Correlations between the surface wettability and spatial variations in liquid density and structure are identified. The self-diffusion coefficient tensor is predicted, revealing highly anisotropic and spatially varying mass transfer phenomena near the solid boundary. This behavior affects self-diffusion at a range of time scales. Near a more-wetting surface, self-diffusion is impeded by strong solid-liquid interactions that induce sharp liquid density gradients and enhanced liquid structure. Conversely, near a less-wetting surface, where solid-liquid interactions are weaker, the liquid density is low, the atoms are disordered, and diffusion is enhanced. These findings suggest that altering the wettability of a micro- or nanochannel may provide a passive means for controlling the diffusion of select targets towards a functionalized surface and controlling the reaction rate in diffusion-limited reactions.
Tunneling current at the interface of silicon and silicon dioxide partly embedded with silicon nanocrystals in metal oxide semiconductor structures
Authors: Chakraborty G. , Chattopadhyay S. , Sarkar C. K. , Pramanik C.
Published: January 2007

A model has been developed to study the tunneling current at the interface of silicon and silicon dioxide (SiO2), partly pure and partly embedded with the silicon nanocrystallites (nc-Si) in a metal oxide semiconductor structure. Two types of tunneling, high field (Fowler-Nordheim) and low field (direct), have been investigated, in particular, their dependence on the barrier height, the effective mass, and the dielectric constant. The presence of the nanocrystallites confined in a narrow layer in the gate dielectric enhances the Fowler-Nordheim (FN) tunneling due to the barrier lowering. The gate current voltage characteristic shows that the total current is a combination of both direct and FN tunneling currents. It is also observed that the onset voltage of the FN tunneling is somewhat reduced in the present case due to the SiO2 layer embedded with the silicon nanocrystallites, compared to the pure SiO2 layer without any nanocrystallites present. The FN tunneling current has also been found to be enhanced with the increase of the volume fraction and the crystallite size of the nanocrystalline silicon.
Br
2
molecular elimination in 248nm photolysis of CHBr2Cl by using cavity ring-down absorption spectroscopy
Authors: Wei Pei-Ying , Chang Yuan-Ping , Lee Yu-Shan , Lee Wei-Bin , Lin King-Chuen , Chen K. T. , Chang A. H. H.
Published: January 2007

Elimination of molecular bromine is probed in the BΠou+3←XΣg+1 transition following photodissociation of CHBr2Cl at 248nm by using cavity ring-down absorption spectroscopy. The quantum yield for the Br2 elimination reaction is determined to be 0.05±0.03. The nascent vibrational population ratio of Br2(v=1)∕Br2(v=0) is obtained to be 0.5±0.2. A supersonic beam of CHBr2Cl is similarly photofragmented and the resulting Br atoms are monitored with a velocity map ion-imaging detection, yielding spatial anisotropy parameters of 1.5 and 1.1 with photolyzing wavelengths of 234 and 267nm, respectively. The results justify that the excited state promoted by 248nm should have an A″ symmetry. Nevertheless, when CHBr2Cl is prepared in a supersonic molecular beam under a cold temperature, photofragmentation gives no Br2 detectable in a time-of-flight mass spectrometer. A plausible pathway via internal conversion is proposed with the aid of ab initio potential energy calculations. Temperature dependence measurements lend support to the proposed pathway. The production rates of Br2 between CHBr2Cl and CH2Br2 are also compared to examine the chlorine-substituted effect.
Hierarchy of effective modes for the dynamics through conical intersections in macrosystems
Authors: Gindensperger Etienne , Köppel Horst , Cederbaum Lorenz S.
Published: January 2007

An extension of the effective-mode theory for the short-time dynamics through conical intersections in macrosystems [L. S. Cederbaum et al., Phys. Rev. Lett. 94, 113003 (2005)] is proposed. The macrosystem, containing a vast number of nuclear degrees of freedom (modes), is decomposed into a system part and an environment part. Only three effective modes are needed—together with the system’s modes—to accurately calculate low resolution spectra and the short-time dynamics of the entire macrosystem. Here, the authors propose an iterative scheme to construct a hierarchy of additional triplets of effective modes. This naturally extends the effective-mode formulation. By taking into account more and more triplets, the dynamics are accurately predicted for longer and longer times, and more resolved spectra can be calculated. Numerical examples are presented, computed using various numbers of additional effective modes.
Investigation of the interaction of a laser pulse with a preformed Gaussian Sn plume for an extreme ultraviolet lithography source
Authors: Tao Y. , Tillack M. S. , Harilal S. S. , Sequoia K. L. , Najmabadi F.
Published: January 2007

The interaction of a laser pulse with a Sn preplasma formed by a low energy prepulse was investigated for an extreme ultraviolet (EUV) lithography light source. A much lower ion kinetic energy and nearly the same conversion efficiency from laser to in-band (2% bandwidth) 13.5nm EUV light were simultaneously observed as compared with those from the direct interaction with a solid surface. The reason comes from the interaction of the laser pulse with a smooth preplume induced by the prepulse. The density profile of the preplume was measured with time-resolved shadowgraphy and could be fitted with a Gaussian function. The energy of the ions located at the flux peak Ep scales with the length of the preplume ls as Ep∝1∕ls. Laser absorption in the low-density preplume and ion acceleration during plasma expansion are discussed. This result provides a general way to control particle energy from a laser plasma interaction.
Calculation of ozone generation by positive dc corona discharge in coaxial wire-cylinder reactors
Authors: Yehia Ashraf
Published: January 2007

A theoretical equation has been derived in this paper for calculation of ozone generation by positive dc corona discharge in coaxial wire-cylinder reactors. The derived equation has been based on the theories of the positive dc coronas reported in the literature and extended to account the ozone destruction within the corona discharge plasma generated in the reactor. The equation has been investigated with experimental results for ozone generated in a coaxial wire-cylinder reactor under different discharge conditions. The reactor was stressed with a positive dc voltage and fed by dry air flowing with constant rates at atmospheric pressure and room temperature. The theoretical results calculated by the derived equation have shown good agreement with the experimental results over the whole range of the investigated parameters. Subsequently, the derived equation is valid to predict the ozone concentration generated in the investigated reactor under any discharge conditions.
Influence of oxygen content on the structural and electrical characteristics of thin neodymium oxide gate dielectrics
Authors: Pan Tung-Ming , Lee Jian-Der , Yeh Wen-Wei
Published: January 2007

The structural properties and electrical characteristics of thin Nd2O3 gate oxides were deposited on silicon substrates by reactive rf sputtering. The structural and morphological features of these films were studied, as a function of the growth conditions (three various argon-to-oxygen flow ratios: 20∕5, 15∕10, and 12.5∕12.5 and temperature from 600to800°C), by x-ray diffraction, atomic force microscopy, and x-ray photoelectron spectroscopy. It is found that Nd2O3 dielectrics with a 12.5∕12.5 ratio condition annealed at 700°C exhibit a thinner capacitance equivalent thickness and excellent electrical properties, including the electric breakdown field, the interface trap density, the hysteresis, and frequency dispersion in the capacitance-voltage curves. This condition is suggested to the reduction of the interfacial SiO2 and silicate formation, and the small of surface roughness due to the optimization of oxygen in the metal oxide film.
Microstructure and high frequency properties of nanogranular CoAlO thin films
Authors: Liu Yan , Tan C. Y. , Liu Z. W. , Ong C. K.
Published: January 2007

Nanogranular CoAlO thin films were fabricated by rf magnetron sputtering using Co target partially covered by Al2O3 chips in argon atmosphere. The films consist of Co nanograins with a mean diameter of 5–30nm surrounded by an amorphous Al–O phase. It was found that Co grains of face-centered-cubic and hexagonal-close-packed structures coexist in the films with relatively low (Al,O) content, whereas Co grains of face-centered-cubic structure are preferentially formed in the films with higher (Al,O) content. Due to the microstructure changes with increasing (Al,O) content in the films, coercivity and magnetization decrease but the anisotropy field increases. The high frequency properties of the CoAlO films were experimentally characterized, and the effects of magnetization, anisotropy field, and damping factor on the permeability spectrum are also analyzed using the Landau-Lifshitz-Gilbert equation. The ferromagnetic resonance frequency was found to increase from 2.1to2.8GHz with the microstructure change in the films.
Schottky mechanism for Ni∕Au contact with chlorine-treated n-type GaN layer
Authors: Chen Po-Sung , Lee Tsung-Hsin , Lai Li-Wen , Lee Ching-Ting
Published: January 2007

To investigate the function of chlorination treatment, Schottky diodes with Ni∕Au contact and chlorine-treated n-type GaN were fabricated. The resultant Schottky barrier height and ideality factor of the chlorine-treated Schottky diodes were improved. The corresponding increase in photoluminescence intensity and carrier lifetime of the chlorine-treated n-type GaN was achieved using photoluminescence and time-resolved photoluminescence measurements. The improved performance of chlorine-treated Schottky diodes was attributed to the reduction of surface states as a result of reduced Ga dangling bonds and the N vacancies being passivated by the formation of GaOx on the surface of n-type GaN.
He induced nanovoids for point-defect engineering in B-implanted crystalline Si
Authors: Bruno E. , Mirabella S. , Priolo F. , Napolitani E. , Bongiorno C. , Raineri V.
Published: January 2007

In this paper we present a systematic study on the formation of He ion implantation induced nanovoids in Si and how they influence the self-interstitial (Is) supersaturation, thus affecting the diffusion and electrical activation of implanted boron in crystalline silicon. We implanted He ions into (100)-oriented Si wafers, with doses ranging from 5×1015to8×1016Heions∕cm2 and energies ranging from 25to110keV. Then, we implanted B ions (12keV, 5×1014ions∕cm2). All samples were annealed at 800°C in N2 atmosphere. We demonstrated the role of nanovoids in reducing B diffusion already at the first stages of postimplantation annealing. The effect has been attributed to the Is trapping by the nanovoids that forces B to assume a boxlike profile. Moreover, we studied the nanovoid distribution as a function of He-implanted dose and energy, demonstrating, by means of Cu gettering experiments, the beneficial effect of increasing dose or decreasing energy of He implantation on the B diffusion and electrical activation. In fact, if the nanovoid density is high in the proximity of implanted B, implantation-related damage can annihilate at the internal dangling bonds of nanovoids, thus consuming the nanovoid layer. The potential of He coimplantation as a method for controlling point-defect distributions in crystalline Si is presented and critically discussed.