bluuebunny/crossref_metadata_2025 huggingface dataset:
69.2: High Efficiency Red‐Emission Phosphorescent Polymer Lighting Emitting Diodes Based on Ir(piq)3 Derivatives
Authors: Huang Jinsong , Yang Yang , Watanabe Taiki , Ueno Kazunori
Published: August 2007

In this paper, several kinds Ir(piq)3 derivatives are used as dopants in polyfluorene to fabricate high performance pure red emission phosphorescent polymer light‐emitting‐diodes. Electron injection/hole blocking layer Cs2CO 3 is inserted between light emitting polymer layer and Al cathode. By modulating the electron injection ability from cathode using Cs2CO3 nano‐thick layer, electron current can be controlled precisely to balance hole current. Peak efficiencies of 16.9 cd/A and 17.6 lm/W at 220cd/m2 is achieved.
From Education to Occupation: The Story of Thomas Bessell Kidner
Authors: Friedland Judith , Davids-Brumer Naomi
Published: August 2007

Background. Thomas Bessell Kidner is well-known in the United States as a great contributor to occupational therapy. He is not well-known in Canada despite the fact that his first contributions to the profession were made here between 1900 and 1918. Purpose. To tell the story of Thomas Bessell Kidner and his impact on occupational therapy. Methods. Interpretive biography research methods using archival materials, published papers and family papers. Results. Kidner's work as an organizer of manual training in elementary schools in Nova Scotia and New Brunswick and as Director of Technical Education for Calgary prepared him for his work as Vocational Secretary of the Military Hospitals Commission during World War I. Kidner developed, implemented and oversaw the reeducation program for injured soldiers across Canada. It included bedside occupations, off-ward and curative workshop activities provided by ward aides, as well as industrial training and apprenticeships in the workplace. Practice Implications. Kidner's story stimulates us to revisit our profession's early emphasis on return-to-work. Knowing about our past helps occupational therapists to build a stronger identity.
How Consumers of Mental Health Services Come to Understand their Potential for Work: Doing and Becoming Revisited
Authors: Gewurtz Rebecca , Kirsh Bonnie
Published: August 2007

Background. Doing and becoming are fundamental constructs in occupational therapy. However, we have little understanding of how these concepts apply to the way that individuals develop ideas about their future in the realm of work. Purpose. This paper examines the doing-becoming interaction and applies it to our understanding of work potential among consumers of community mental health services. Methods. Using a grounded theory approach, 10 consumers were interviewed about their experiences with paid and unpaid work. Data were analyzed inductively according to the constant comparative approach. Results. The findings reveal that doing and becoming are essential to the process of how consumers develop ideas about their potential for work. Through doing work, consumers gain insight into their capacity for future work participation and become persons with possible work futures. Practice Implications. An occupational perspective on career development challenges occupational therapists to create opportunities for doing and becoming among consumers.
Initial Vertical and Horizontal Position of Palatally Impacted Maxillary Canine and Effect on Periodontal Status Following Surgical-Orthodontic Treatment
Authors: Zasciurinskiene Egle , Bjerklin Krister , Smailiene Dalia , Sidlauskas Antanas , Puisys Algirdas
Published: August 2007

Objective: To evaluate the impact of surgical-orthodontic treatment and the initial vertical and mesiodistal position of palatally impacted maxillary canines on the periodontal health of impacted canines and adjacent teeth.

Materials and Methods: The study group consisted of 32 patients with unilateral palatally impacted maxillary canines. The initial position of the impacted canines was assessed on panoramic images. The treatment protocol of the impacted canines included surgical exposure with the closed-eruption technique and fixed orthodontic appliances.

Results: A significant increase in pocket depth was found at the canine mesiopalatal point after surgical-orthodontic treatment. Also, a correlation was found between the initial mesiodistal and vertical position of the impacted canine and the posttreatment periodontal status of the impacted canine, the adjacent lateral incisor, and the first premolar.

Conclusions: A combined surgical-orthodontic approach in the treatment of impacted maxillary canines produces clinically acceptable periodontal conditions. The average increase in pocket depth was less than 4 mm and clinically unimportant for most patients.
Dentofacial Changes after Orthodontic Intervention with Eruption Guidance Appliance in the Early Mixed Dentition
Authors: Keski-Nisula Katri , Keski-Nisula Leo , Salo Hannu , Voipio Kati , Varrela Juha
Published: August 2007

Objective: To evaluate skeletal and dentoalveolar changes induced by the eruption guidance appliance in the early mixed dentition.

Materials and Methods: Pre- and posttreatment cephalometric radiographs of 115 consecutively treated children, 62 boys and 53 girls, were compared with those obtained from a control group of 104 children, 52 boys and 52 girls. Pretreatment radiographs were taken at the deciduous-mixed dentition interphase (T1) and after full eruption of all permanent incisors and first molars (T2). The mean age of the children in both groups was 5.1 years at T1 and 8.4 years at T2.

Results: A significant difference between the groups at T2 was found in the mandibular length, midfacial length, and maxillomandibular differential. The increase in mandibular length was 11.1 mm in the treatment group and 7.2 mm in the control group. No differences were found in measurements of maxillary position or size. There was a significant shift toward a Class I relationship in the treatment group. Labial tipping and linear protrusion of the mandibular incisors was evident in the treatment group at T2. There was no effect on the inclination or position of the maxillary incisors.

Conclusions: Occlusal correction was achieved mainly through changes in the dentoalveolar region of the mandible. In addition, the appliance enhanced condylar growth resulting in a clinically significant increase in mandibular length. No effect was observed on maxillary position, maxillary size, inclination or protrusion of the maxillary incisors, or facial height.
Bond Strength of an Amorphous Calcium Phosphate–Containing Orthodontic Adhesive
Authors: Foster Jeff A. , Berzins David W. , Bradley Thomas G.
Published: August 2007

Objective: To determine whether an amorphous calcium phosphate (ACP)-containing adhesive has an acceptable level of shear bond strength to be used as an orthodontic adhesive.

Materials and Methods: Sixty extracted premolars were randomly divided into three groups for orthodontic bonding. Group 1 used a composite resin adhesive (Transbond XT), group 2 was bonded with an ACP-containing adhesive (Aegis Ortho), and group 3 used a resin-modified glass ionomer (Fuji Ortho LC). All bonded teeth were stored in distilled water at 37°C for 40 ± 2 hours prior to debonding. Shear bond strength and adhesive remnant index (ARI) were recorded for each specimen.

Results: The mean shear bond strengths for the three test groups were: group 1 (15.2 ± 3.6 MPa), group 2 (6.6 ± 1.5 MPa), and group 3 (8.3 ± 2.8 MPa). A one-way analysis of variance showed a significant difference in bond strengths between the groups. A post hoc Tukey test showed group 1 to be significantly (P < .001) greater than groups 2 and 3. A Kruskal-Wallis test and a Mann-Whitney U-test showed groups 1 and 3 exhibited lower ARI scores than group 2, but a majority of specimens in each group had greater than 50% of the cement removed along with the bracket during debonding.

Conclusions: The ACP-containing adhesive demonstrated a low, but satisfactory bond strength needed to function as an orthodontic adhesive.
Rapid Maxillary Expansion Effects on Nocturnal Enuresis in Children
Authors: Schütz-Fransson Ulrike , Kurol Jüri
Published: August 2007

Objective: To assess the effects of 10–14 days of rapid maxillary expansion (RME) on nocturnal enuresis (NE) in children who have long-standing resistance to medical therapy and to evaluate the long-term success rate after 10 years.

Materials and Methods: Twenty-three children with NE, aged 6–15 years old (mean age = 10), who wet their bed almost every night and had never been dry were referred from pediatric specialists. Mean RME was 6.5 mm (range = 5–8), but only 7 of the 23 patients had lateral crossbites. Rhinomanometric measurements were taken before and after RME, and patients were interviewed 10 years after treatment.

Results: Positive effects of RME were observed in nearly 50% of the patients within 1 month of treatment: six were completely dry and five had notable improvements. Relapse in the overexpanded arches to a normal transversal occlusion was noted within 1 year. No correlation was found between success and improved airways, familial heritage, school performance, or other social factors. Younger children responded better to the treatment. Results were stable at the 10-year follow-up, and no adverse reactions were reported.

Conclusion: Orthodontic RME is a new option for treating children with NE who are resistant to medical therapy; the treatment has no adverse side effects.
Impacts on Daily Performances Attributed to Malocclusions Using the Condition-Specific Feature of the Oral Impacts on Daily Performances Index
Authors: Bernabé Eduardo , Tsakos Georgios , Messias de Oliveira Cesar , Sheiham Aubrey
Published: August 2007

Objective: To assess the prevalence, intensity, and extent of sociodental impacts attributed to malocclusions by sex, socioeconomic status, and normative orthodontic treatment need level.

Materials and Methods: One thousand sixty 15- to 16-year-old adolescents without history of previous or current orthodontic treatment were randomly selected from all secondary schools in Bauru, Brazil. Interviews were done to collect information about sociodemographic variables and sociodental impacts on quality of life attributed to malocclusions using the Oral Impacts on Daily Performances Index. Adolescents were also clinically examined using the Index of Orthodontic Treatment Need. Statistical comparison by covariables was performed using χ2 and Kruskal-Wallis tests.

Results: The prevalence of condition-specific impacts (CSIs) was 24.6%. Among adolescents with CSIs, 52.1% reported severe or very severe intensity and 77.4% reported impacts on only one daily performance, commonly, smiling. The prevalence, intensity, and extent of CSIs differed by level of normative orthodontic treatment need but not by sex or socioeconomic status. However, among adolescents with definite normative orthodontic treatment need, 24.5% reported CSIs of severe or very severe intensity, whereas among those with moderate or slight/no need, 13.0% and 7.9%, respectively, experienced CSIs of severe or very severe intensity.

Conclusions: Untreated malocclusions have physical, psychological, and social consequences on quality of life of Brazilian adolescents. However, because adolescents with a definite normative orthodontic need are considered by orthodontists as in need of care, these results raise the issue of whether all these adolescents should be considered for orthodontic attention since most had no perceived impacts on performing their daily life activities.
Class II Non-Extraction Patients Treated with the Forsus Fatigue Resistant Device Versus Intermaxillary Elastics
Authors: Jones Graham , Buschang Peter H. , Kim Ki Beom , Oliver Donald R.
Published: August 2007

Objective: To evaluate the Forsus Fatigue Resistant Device (FRD) as a compliance-free alternative to Class II elastics.

Materials and Methods: A sample of 34 (14 female, 20 male) consecutively treated nonextraction FRD patients (12.6 years of age) were matched with a sample of 34 (14 female, 20 male) consecutively treated nonextraction Class II elastics patients (12.2 years of age) based on four pretreatment variables (ANB, L1-GoMe, SN-GoMe, and treatment duration). Pretreatment and posttreatment cephalometric radiographs were traced and analyzed using the pitchfork analysis and a vertical cephalometric analysis. t-Tests were used to evaluate group differences. Group differences were evaluated using t-tests.

Results: No statistically significant differences were found in the treatment changes between the groups. There was a general trend for mesial movement of the maxilla, mandible, and dentition during treatment for both groups. The mandibular skeletal advancement and dental movements were greater than those in the maxilla, which accounted for the Class II correction. Lower incisor proclination was evident in both groups. Vertically, the maxillary and mandibular molars erupted during treatment in both groups, while lower incisors proclined. With the exception of lower molar mesial movements and total molar correction, which were significantly (P < .05) greater in the Forsus group, there were no statistically significant group differences in the treatment changes.

Conclusions: The Forsus FRD is an acceptable substitute for Class II elastics for noncompliant patients.
Displaced Premolars in Panoramic Radiography—Fact or Fallacy?
Authors: Nohadani Nasila , Pohl Yango , Ruf Sabine
Published: August 2007

Objective: To test the null hypothesis that there is no difference between premolar position visualized on panoramic radiographs (PRs) and lateral headfilms (LHs).

Materials and Methods: The prevalence of differences in the direction of crown angulation between PR and LH was assessed. Furthermore, brass wire markers with different sagittal and transverse angulations were placed in a dry skull. With the markers in place, LHs and PRs were taken.

Results: A difference in the direction of crown angulation of unerupted second premolars between PR and LH occurred in 19.5% of patients. The reason for the angulation differences is a buccolingual orientation of the tooth, which appears as a mesiodistal angulation on the PR.

Conclusion: The null hypothesis was rejected since in one-fifth of the patients premolar projection differs between the panoramic radiograph and the lateral headfilm.
Does Rapid Maxillary Expansion Affect the Eruption of Upper Third Molars?
Authors: Sökücü Oral , Öztürk Fırat , Babacan Hasan , Bıçakçı Ali Altuğ
Published: August 2007

Objective: To test the hypothesis that there is no difference in the movement of the upper third molars between rapid maxillary expansion (RME) and non-RME patients.

Materials and Methods: This study was performed on 30 patients divided into two groups. The study group included 20 patients who had maxillary narrowness and bilateral maxillary third molars and who had undergone RME application. The control group of 10 patients had a bilateral crossbite, had bilateral maxillary third molars, and did not receive orthodontic treatment. The records included lateral and frontal cephalometric films and maxillary plaster models. In the study group, records were taken before expansion (T1), after expansion (T2), and at the retention period (T3). T2 records were not taken in the control group because this period was too short to observe any changes. Friedman tests were used to observe within groups, and the Mann-Whitney U-test was used to see the differences between groups on films and casts.

Results: Frontal films showed that vertical eruption occurred after the retention period in the RME cases. Cephalometric films revealed that the angular eruption occurred immediately after expansion. However, the results were not significant with respect to the control group.

Conclusion: The hypothesis was rejected. Rapid maxillary expansion affects maxillary third molar movement during and after the RME procedure. RME may indicate upper third molar eruption, but the final position of third molar was not different compared to the normal growth pattern.
Immediate Skeletal and Dentoalveolar Effects of the Crown- or Banded Type Herbst Appliance on Class II division 1 Malocclusion
Authors: Barnett Gregory A. , Higgins Duncan W. , Major Paul W. , Flores-Mir Carlos
Published: August 2007

Objective: To evaluate the relative skeletal and dental changes produced by the crown- or banded-type Herbst appliance in growing Class II division 1 malocclusion cases.

Materials and Methods: Several electronic databases were searched with the help of a health sciences librarian, without language limitation. Abstracts that appeared to fulfill the initial selection criteria (Herbst use and clinical trial) were selected by consensus, and their original articles were then retrieved. Clinical trials were selected that used lateral cephalograms to assess immediate skeletal and dental changes from the use of either crown or banded Herbst appliances. Clinical trials that employed other simultaneous potentially growth-modifying appliances or surgery were excluded. A comparable untreated Class II division 1 malocclusion control group was required to factor out normal growth changes. References from the selected articles were also hand searched.

Results: Only three articles meet the selection criteria. Proclination and anterior movement of the lower incisors, overjet reduction, and improvement of first molar relationship thorough mesial movement of the first molars, reduction of ANB angle, and an increase in the mandibular plane angle were reported. There were mixed findings as to mandibular sagittal length and position and increases in lower face height, both anteriorly and posteriorly. No statistically significant changes were noted in the sagittal length or position of the skeletal maxilla.

Conclusions: Dental changes have more impact than skeletal changes in the correction of Class II division 1 malocclusions with the crown or banded Herbst appliance.
Clinical Effect of CO2 Laser in Reducing Pain in Orthodontics
Authors: Fujiyama Koji , Deguchi Toru , Murakami Takashi , Fujii Akihito , Kushima Kazuhiko , Takano-Yamamoto Teruko
Published: August 2007

Objective: To test the hypothesis that there is no difference in the pain associated with orthodontic force application after the application of local CO2 laser irradiation to the teeth involved.

Materials and Methods: Separation modules were placed at the distal contacts of the maxillary first molars in 90 patients in this single-blinded study. In 60 of these patients (42 females and 18 males; mean age = 19.22 years) this was immediately followed by laser therapy. The other 30 patients (18 females and 12 males; mean age = 18.8 years) did not receive active laser irradiation. Patients were then instructed to rate their levels of pain on a visual analog scale over time, and the amount of tooth movement was analyzed.

Results: Significant pain reductions were observed with laser treatment from immediately after insertion of separators through day 4, but no differences from the nonirradiated control side were noted thereafter. No significant difference was noted in the amount of tooth movement between the irradiated and nonirradiated group.

Conclusions: The hypothesis was rejected. The results suggest that local CO2 laser irradiation will reduce pain associated with orthodontic force application without interfering with the tooth movement.
Anterior Open Bite and Speech Disorders in Children with Down Syndrome
Authors: López-Pérez Rubén , Borges-Yáñez S. Aida , López-Morales Patricia
Published: August 2007

Objective: To estimate the prevalence and to determine if there is an association between anterior open bite and the presence of speech disorders in a group of Mexican children with Down syndrome (DS).

Materials and Methods: The subjects were a group of Mexican children with Down syndrome (DG) and a control group (CG) of Mexican pediatric patients without disabilities matched by age. The children in both groups came from families having children with anterior open bite and children without it. A parental questionnaire, dental study casts, and a speech test were used to measure the studied variables. Data were analyzed using the chi-square test (χ2 test), and one-way analyses of variance (ANOVA), followed by the Tukey post hoc test.

Results: Prevalence of anterior open bite was 31.6% in the DG and 22.8% in the CG. The total speech errors by omissions, substitutions, distortions, and additions indicated that there were significant differences between both groups (F = 31.68, P < .001). In general, no significant difference in speech disorders was observed between the DG and the CG regardless of the presence of anterior open bite.

Conclusions: No association existed between speech disorders and anterior open bite in the samples studied.
Witkop Tooth and Nail Syndrome and Orthodontics
Authors: Altug-Atac Ayse T. , Iseri Haluk
Published: August 2007

This case report presents the orthodontic treatment of a patient with Witkop syndrome, an autosomal dominant genetic disorder characterized by the absence of several teeth and abnormalities of the nails. The patient, a 6-year 4-month-old boy, was referred to our clinic for treatment of severe overjet and openbite. Radiographic and clinical evaluations showed peg-shaped maxillary lateral incisors and the congenital absence of three mandibular incisors as well as spoon-shaped fingernails. Treatment of openbite and overjet was initiated with functional appliances, and fixed orthodontic appliances were inserted at age 10 years 3 months. The edentulous spaces are being maintained for implants that will be provided once the patient's growth is complete. Evaluations of long-term treatment results to date have indicated improvements in both facial and dental esthetics.
Polarized Versus Nonpolarized Digital Images for the Measurement of Demineralization Surrounding Orthodontic Brackets
Authors: Benson Philip Edward , Ali Shah Anwar , Robert Willmot Derrick
Published: August 2007

Objective: To compare the assessment of demineralized white lesions surrounding orthodontic brackets using images produced with and without polarizing filters to reduce incidental flash reflection.

Materials and Methods: Thirty teeth with orthodontic brackets and a systematic arrangement of artificially induced demineralization were used. Standardized digital images of the teeth were taken with and without a cross-polarizing filter. These were repeated after 1 week. All the images were randomly numbered and assessed by an investigator, unaware as to the nature of the study. The presence or absence of demineralization was recorded and compared with the actual demineralization pattern. The lesion area and degree of whiteness (LI%) were measured using computerized image analysis. Twenty images from each group were randomly chosen and duplicated for an assessment of measurement error.

Results: The positive and negative predictive values were better from the polarized images (0.97 and 0.84, respectively) than from the nonpolarized images (0.90 and 0.74, respectively). The percentage agreements for the repeat assessments of the same slide were better for the polarized images (96%) than for the nonpolarized images (89%). The limits of agreement and intraclass correlation coefficients between measurements of repeated images were lower for lesion area from cross-polarized images, suggesting better reproducibility, but not for LI%.

Conclusion: A cross-polarization filter enhances the subjective assessment of demineralized lesions surrounding an orthodontic bracket and improves the reproducibility of measuring the lesion area. The filter did not improve the assessment of changes in enamel gray levels with demineralization.
Mathematical Analyses of Dental Arch Curvature in Normal Occlusion
Authors: AlHarbi Seba , Alkofide Eman A. , AlMadi Abdulaziz
Published: August 2007

Objective: To present a comprehensive mathematical analysis of dental arch curvature in subjects with normal occlusion.

Materials and Methods: The materials studied were 40 sets of upper and lower plaster dental casts of subjects presenting with normal occlusion. The sample was equally divided into casts from male and female subjects with an age range from 18 to 25 years. Curve-fitting analyses was carried out and four main categories of functions were considered: the beta function, natural cubic splines, polynomial equations, and Hermite cubic splines.

Results: The polynomial function (fourth order) was found to be a reasonable analysis when the objective is to describe the general smooth curvature of the dental arch, while a Hermite cubic spline is more appropriate when it is desired to track arch irregularities, such as evaluating treatment changes.

Conclusions: Due to its advantage in providing a more naturally smooth curve, the fourth-order polynomial function may be used as a guide to fabricate customized arch wires, or even an entire fixed orthodontic appliance system.
Thermocycling Effects on Shear Bond Strength of a Self-Etching Primer
Authors: Elekdag-Turk Selma , Turk Tamer , Isci Devrim , Ozkalayci Nurhat
Published: August 2007

Objective: To determine the effects of thermocycling on shear bond strengths (SBSs) of a self-etching primer (SEP) after 0, 2000, and 5000 thermal cycles.

Materials and Methods: Brackets were bonded to bovine incisors with two etching protocols. In the control group (conventional method) teeth were etched with 37% phosphoric acid. In the experimental group, an SEP (Transbond Plus) was applied as recommended by the manufacturer. Brackets were bonded with light-cure adhesive paste (Transbond XT) and light cured for 20 seconds in both groups. The SBSs were measured after water storage at 37°C for 24 hours, after 2000 and 5000 cycles of thermocycling between 5°C and 55°C. Bond failure location was determined with the Adhesive Remnant Index (ARI).

Results: In the control group, SBSs did not show any significant differences among 0, 2000, and 5000 thermal cycles. However, in group SEP, SBSs decreased with 2000 and 5000 thermal cycles, and these decreases were significantly different from no thermocyling (P < .001). A significant difference was observed between ARI scores of the control group with 5000 thermal cycles and group SEP with no thermal cycles (P < .003). In addition, a significant difference was found between group SEP with no thermocycling and with 5000 thermal cycles (P < .003).

Conclusion: The results of this study indicate that the SEP (Transbond Plus) provides clinically acceptable bond strength values compared with the conventional method after thermocycling.
The intensity of recent and distant life regrets: an integrated model and a large scale survey
Authors: Bonnefon Jean‐François , Zhang Jiehai
Published: August 2007

The research considers three predictors of the intensity of life regrets: (a) whether the regretted behaviour is an action or a failure to act, (b) the severity of its consequences and (c) the extent to which the behaviour was justified. It is hypothesised that the intensity of recent and distant regrets will be predicted by different combinations of these predictors. Regression analyses on regrets reported by 957 French adults support this hypothesis. The intensity of recent regrets is predicted by the consequences of the behaviour, and especially so for actions. The intensity of distant regrets is predicted by the consequences of the behaviour and by its justification, the effect of justification being stronger for actions than for inactions. These results are discussed in relation to both laboratory and field studies of regret. Copyright © 2007 John Wiley & Sons, Ltd.
Computer‐mediated communication: synchronicity and compensatory effort
Authors: Münzer Stefan , Borg Anna
Published: August 2007

Groups might perform compensatory communicative actions if media characteristics impede a particular communication process. The present study examined this hypothesis for the process of information integration, which is a sub‐task in collaborative problem‐solving. Synchronous media characteristics support the information integration process, while asynchronous media characteristics impede it. The synchronicity of the medium was varied by manipulating parallelism and the immediacy of feedback within real‐time, text‐based computer‐mediated communication. A Conversational Games Analysis (CGA) was performed in order to investigate the functional purposes of the task‐oriented contributions. All groups successfully solved the problem. However, groups interacting in the asynchronous communication mode produced significantly more functional contributions for the purpose of mutual task‐oriented understanding and clarification, compared to the synchronous groups. Moreover, members of asynchronous groups repeated unshared pieces of information more often. These differences are interpreted as communicative efforts that balance the hindering influence of asynchronous media characteristics on the process of information integration. Copyright © 2007 John Wiley & Sons, Ltd.
Safety verification and adaptive model predictive control of the hybrid dynamics of a fuel cell system
Authors: Fiacchini M. , Alamo T. , Alvarado I. , Camacho E. F.
Published: August 2007

The problem of safety verification of a fuel cell (FC) system is addressed in this paper. The aim of safety verification is to check whether the oxygen ratio can reach dangerous values or not. Assuming that the compressor voltage is controlled by means of a feedforward control, two algorithms for safety verification are formulated and applied to the PWA model of the FC. An improved behavior is obtained using an adaptive predictive controller to determine the voltage to be applied to the compressor. An admissible robust control invariant set for the PWA model of the system is computed. The control action of the predictive controller is obtained in such a way that the state is always included in the safe region provided by the admissible robust control invariant set. This guarantees that the proposed controller always provides safe evolutions of the system. Copyright © 2007 John Wiley & Sons, Ltd.
Adaptive hybrid predictive control for a combined cycle power plant optimization
Authors: Sáez D. , Zúñiga R. , Cipriano A.
Published: August 2007

The design and development of an adaptive hybrid predictive controller for the optimization of a real combined cycle power plant (CCPP) are presented. The real plant is modeled as a hybrid system, i.e. logical conditions and dynamic behavior are used in one single modeling framework. Start modes, minimum up/down times and other logical features are represented using mixed integer equations, and dynamic behavior is represented using special linear models: adaptive fuzzy models. This approach allows the tackling of special non‐linear characteristics, such as ambient temperature dependence on electrical power production (combined cycle) and gas exhaust temperature (gas turbine) properly to fit into a mixed integer dynamic (MLD) model. After defining the MLD model, an adaptive predictive control strategy is developed in order to economically optimize the operation of a real CCPP of the Central Interconnected System in Chile. The economic results obtained by simulation tests provide a 3% fuel consumption saving compared to conventional strategies at regulatory level. Copyright © 2007 John Wiley & Sons, Ltd.
Multiple robust track‐following controller design in hard disk drives
Authors: Choi Jongeun , Nagamune Ryozo , Horowitz Roberto
Published: August 2007

This paper presents a new technique for track‐following control in hard disk drives, in order to achieve high tracking precision of magnetic read–write headsuniformlyfor a huge number of disk drives. The basic idea in this technique is to classify the disk drives into several sets depending on dynamics properties, and to apply a robust controller to each set. The problem of designing the optimal classification of dynamics and the corresponding optimal robust controllers is formulated as a nonconvex optimization problem, for which sub‐optimal solutions are to be found numerically. A numerical simulation shows the usefulness of the proposed technique by illustrating a tracking performance improvement. Copyright © 2007 John Wiley & Sons, Ltd.
Application of model‐free LQG subspace predictive control to TCP congestion control
Authors: Chiera Belinda A. , White Langford B.
Published: August 2007

We investigate the application of a model‐free linear quadratic Gaussian (LQG) subspace‐based predictive controller to Internet congestion control. Specifically, we consider a classically designed LQG linear congestion controller with a non‐standard performance index and determine whether a model‐free controller is a viable alternative in this instance. We employ the model‐free subspace predictive controller methodology which we customize for end‐to‐end transmission control protocol (TCP) congestion control. A series of network simulations support the use of the more easily implementable model‐free controller over its classical analogue. We further demonstrate that the model‐free controller provides increased stability under transient network conditions when compared with the first feedback congestion controller, TCP Vegas. Copyright © 2007 John Wiley & Sons, Ltd.
Colloidal Photonic Crystals Doped with Gold Nanoparticles: Spectroscopy and Optical Switching Properties
Authors: Morandi V. , Marabelli F. , Amendola V. , Meneghetti M. , Comoretto D.
Published: August 2007

Polystyrene artificial opals with few gold nanoparticles (AuNp) embedded in the interstices (doping) are grown by using the meniscus technique starting from a mixed suspension of microspheres and AuNp. Samples having different sphere diameters and nanoparticle loads have been prepared. Their reflectance spectra clearly show a dramatic bathochromic shift of the photonic stop band (up to 1400 cm–1) and a reduction of its full width half maximum, due to an increase of the effective refractive index of about 8 % with respect to bare opals, which is accounted for by analytical theoretical models. Reflectance spectra do not show any direct evidence of AuNp absorption even at the higher AuNp doping level. Nanosecond transient absorption measurements on these systems indicate that a variation of transmission (optical switching) of about 150 % is observed for AuNp doped opals upon photoexcitation with 9 ns laser pulses at 532 nm. No switching is instead observed for bare opals.
Synthesis of NaYF4 Nanocrystals with Predictable Phase and Shape
Authors: Liang X. , Wang X. , Zhuang J. , Peng Q. , Li Y.
Published: August 2007

In this Full Paper, a water/alcohol/oleic acid system was developed to prepare NaYF4 nanocrystals with predictable size, shape and phase. The structural and kinetic factors that govern the phase and shape evolution of NaYF4 nanocrystals have been carefully studied, and the influence of NaF to Y3+ ratio, reaction time and temperature on the phase and shape evolution of the as‐prepared NaYF4 samples was systematically investigated and discussed. It was found that the NaF to Y3+ ratio was responsible for the shape evolution while temperature and reaction time was the key for the phase control of the NaYF4 nanocrystals. This study would be suggestive for the precisely controlled growth of inorganic nanocrystals, especially for those usually crystallizing in diverse crystal structures.
Polypyrrole Microtubule Actuators for Seizing and Transferring Microparticles
Authors: He X. M. , Li C. , Chen F. E. , Shi G. Q.
Published: August 2007

Bilayer actuators consisting of a layer of aligned PPy microtubules with the length of 15 μm and a layer of compact PPy film with the thickness of 15 μm have been fabricated. The actuators can bend to an angle much larger than 90° at an actuation rate of ∼ 100° s–1 under a driving potential of 0.8 V versus Ag/AgCl. The microtubule layers of both type actuators are “sticky”, and can capture or trap polystyrene microparticles from their dilute dispersions. Moreover, the captured particles can be extensively released by sonication or partly released by electrochemically reducing the actuators in the aqueous electrolytes. On the basis of extensive investigations including controlling the conditions of electrochemical actuation and the redox states of PPy microtubules, adjusting the particle size and composition, possible mechanisms for capturing and releasing microparticles were proposed.
Saccharide Blocking Layers in Solid State Dye Sensitized Solar Cells
Authors: Handa S. , Haque S. A. , Durrant J. R.
Published: August 2007

The adsorption of saccharides on dye sensitized, nanocrystalline metal oxide films is shown to improve the efficiency of solid state dye sensitized solar cells. The function of the saccharide treatment is evaluated by transient optical studies, and correlated with device photovoltaic performance. A range of saccharides, including cyclodextrins and their linear analogue amylose, are investigated. The saccharide blocking layer is shown to retard interfacial charge recombination losses, resulting in increased device open circuit voltage. Highest device performance is achieved with linear saccharide amylose, resulting in a 60 % improvement in device efficiency relative to the non‐treated control, with a device open circuit voltage of 1 V.
Mechanical Properties and Flame‐Retardant Behavior of Ethylene Vinyl Acetate/High‐Density Polyethylene Coated Carbon Nanotube Nanocomposites
Authors: Peeterbroeck S. , Laoutid F. , Taulemesse J.‐M. , Monteverde F. , Lopez‐Cuesta J.‐M. , Nagy J. B. , Alexandre M. , Dubois P.
Published: August 2007

High‐density polyethylene coated multiwalled carbon nanotubes (c‐MWNTs) and multiwalled carbon nanotubes (MWNTs) have been dispersed into an ethylene vinyl acetate (EVA) copolymer by mechanical kneading. The effect of c‐MWNTs on tensile properties, thermo‐oxidative degradation, and fire behavior has been studied in comparison with virgin EVA and EVA/MWNTs nanocomposites. Due to the better dispersion of the coated nanotubes, the incorporation of 3 wt % of c‐MWNTs leads to an increase of the Young's modulus, the cohesion of the combustion residues, and a decrease of the peak heat‐release rate.
Fluorescence Quenching upon Binding of Copper Ions in Dye‐Doped and Ligand‐Capped Polymer Nanoparticles: A Simple Way to Probe the Dye Accessibility in Nano‐Sized Templates
Authors: Gouanvé F. , Schuster T. , Allard E. , Méallet‐Renault R. , Larpent C.
Published: August 2007

The synthesis and properties of well‐defined core–shell type fluorescent metal‐chelating polymer nanoparticles NP, in the 15 nm diameter range, with a fluorophore (9,10‐diphenylanthracene: DPA) entrapped in the particle core and a selective ligand (1,4,8,11‐tetraazacyclotetradecane: Cyclam), grafted onto the surface are presented. NPs with different number of dye‐per‐particle are readily obtained by entrapment of the fluorophore within the polymer core. The ligand‐coated NPs exhibit a high affinity for Cu2+ ions in aqueous solution and quenching of the DPA fluorescence is observed upon binding of copper. The quenching of fluorescence arises through energy transfer (FRET) from the dye to the copper‐cyclam complexes that form at the NP surface with an operating distance (d) in the 2 nm range. A simple core–shell model accounts for the steady‐state and time‐resolved fluorescence titration experiments: dye molecules located in the outer sphere (thickness d) of the NPs are quenched while the fluorescence of dyes embedded more deeply is not affected by the binding of copper ions. The observed high quenching efficiency (60–65 %), which is tightly correlated to the volumic and microstructural features of the NPs, shed light on the enhanced accessibility inherent in nano‐sized templates. The response towards different metal ions was investigated and this confirmed the selectivity of the nanoparticle template‐assembled sensor for cupric ions.
Tough, Semiconducting Polyethylene‐poly(3‐hexylthiophene) Diblock Copolymers
Authors: Müller C. , Goffri S. , Breiby D. W. , Andreasen J. W. , Chanzy H. D. , Janssen R. A. J. , Nielsen M. M. , Radano C. P. , Sirringhaus H. , Smith P. , Stingelin‐Stutzmann N.
Published: August 2007

Semiconducting diblock copolymers of polyethylene (PE) and regioregular poly(3‐hexylthiophene) (P3HT) are demonstrated to exhibit a rich phase behaviour, judicious use of which permitted us to fabricate field‐effect transistors that show saturated charge carrier mobilities, μFET, as high as 2 × 10–2 cm2 V–1 s–1 and ON‐OFF ratios, Ion/Ioff ∼ 105 at contents of the insulating PE moiety as high as 90 wt %. In addition, the diblock copolymers display outstanding flexibility and toughness with elongations at break exceeding 600 % and true tensile strengths around 70 MPa, opening the path towards robust and truly flexible electronic components.
Electro‐Optical Study of Subphthalocyanine in a Bilayer Organic Solar Cell
Authors: Gommans H. H. P. , Cheyns D. , Aernouts T. , Girotto C. , Poortmans J. , Heremans P.
Published: August 2007

Ultra‐thin films of subphthalocyanine (SubPc) were grown onto Si/SiO2 substrates by organic molecular beam deposition and the complex refractive index has been characterized by spectroscopic ellipsometry. The peak maximum in the extinction coefficient is determined to be 1.6 at 590 nm and the dielectric constant equals 3.9 in the limit of long wavelength. These values are extraordinary high when compared to the well‐known metal‐phthalocyanines and will be beneficial for the performance in a photovoltaic cell. The amorphous SubPc structure on top of indium‐tin‐oxide (ITO) as well as quartz glass is imaged by atomic force microscopy and scanning electron microscopy and we have characterized the nearly flat surface topology. Next, subphthalocyanine films in combination with buckminsterfullerene (C60) have been studied in a planar bilayer donor/acceptor heterojunction by current density‐voltage characterization under AM 1.5 simulated illumination at various light intensities. A power conversion efficiency of 3.0 % under 1 sun was measured. Finally, the external and internal quantum efficiencies demonstrated peak maxima at 590 nm of 46 % and 55 %, respectively. Considering the abrupt junction at the donor/acceptor interface, the electron transfer from SubPc to the acceptor material is thus determined to be highly efficient.
Boron Nitride Nanotubes
Authors: Golberg D. , Bando Y. , Tang C. C. , Zhi C. Y.
Published: August 2007

The current status of research on boron nitride nanotubes (BNNTs)—carbon nanotube structural analogues—is discussed. Latest achievements in BNNT synthesis, morphology, and atomic structure analysis as well as physical, chemical, and functional property evaluations are reviewed. Similarities and differences between structural parameters and properties of BNNTs in comparison with conventional carbon nanotubes are particularly highlighted. Recent breakthroughs in BNNT filling, doping and functionalization, morphology, and electronic structure engineering are examined. Finally, prospective BNNT applications for fabricating field‐effect transistors, gas accumulators, and reinforcing polymer films are presented.
Inside Front Cover: Towards Understanding Why a Superhydrophobic Coating Is Needed by Water Striders (Adv. Mater. 17/2007)
Authors: Shi F. , Niu J. , Liu J. , Liu F. , Wang Z. , Feng X.‐Q. , Zhang X.
Published: August 2007

Gold threads modified with superhydrophobic or normal hydrophobic coatings are used as model system in the study of the contribution of a superhydrophobic coating of water striders to their floating and movement on water surfaces. After depositing Pt aggregates on one of its ends, the gold threads are able to move in the H2O2 aqueous solution. The superhydrophobic coating is proven to be able to decrease fluidic drag during motion, as described by Xi Zhang and co‐workers on p. 2257.
N‐Arylation of Heterocycles with Activated Chloro‐ and Fluoroarenes using Nanocrystalline Copper(II) Oxide
Authors: Kantam M. Lakshmi , Yadav Jagjit , Laha Soumi , Sreedhar Bojja , Jha Shailendra
Published: August 2007

Nanocrystalline copper oxide was found to be an effective heterogeneous catalyst for the N‐arylation of heterocycles with activated chloro‐ and fluoroarenes using potassium carbonate as base. N‐Arylated products were isolated in good to excellent yields. The catalyst can be used for five cycles with almost consistent activity.
A Practical Synthesis of Multifunctional Ketones through the Fukuyama Coupling Reaction
Authors: Mori Yoshikazu , Seki Masahiko
Published: August 2007

A highly efficient, robust and scalable protocol for the synthesis of multifunctional ketones through Fukuyama coupling, i.e., cross‐coupling of thiol esters with zinc reagents, has been developed. Treatment of thiol esters with alkylzinc iodides or dialkyl zincs in the presence of palladium on activated carbon (Pd/C) or palladium acetate [Pd(OAc)2] furnished the corresponding ketones in high yields. Evaluation of the properties‐activities relationship of the Pd/C‐catalyzed reaction has proven that oxidic Pd/C is much more potent than reduced Pd/C in the reaction of thiolactone1awith zinc reagent2a. Based on the dependence of the Pd/C‐catalyzed reaction on the nature of Pd/C in combination with the extent of the Pd leaching from Pd/C to the solution, a dual reaction mechanism for the Pd/C‐catalyzed Fukuyama coupling reaction, which includes heterogeneous and homogeneous catalytic cycles, was proposed. The marked reduction of the zinc reagents and the use of Pd(OAc)2in much smaller amounts were achieved when zinc bromide was added. This supports a hypothesis where a shift of the Schlenk equilibrium from inactive dialkylzincs (R2Zn) to active organozinc species, such as alkylzinc halides (RZnX) and three‐coordinate species [(RZnX2)−⋅ (ZnX)+], and generation of the stabilized monomeric Pd complexes during the reaction, may facilitate the reaction.
Incorporation of Primary Amines into a Polyester Chain by a Combination of Chemical and Lipase‐Catalyzed ε‐Caprolactone Ring‐Opening Processes
Authors: Marzorati Mattia , Hult Karl , Riva Sergio , Danieli Bruno
Published: August 2007

A simple chemoenzymatic strategy for the incorporation of bioactive and suitably functionalized molecules into a polyester chain has been developed. The protocol involves first the reaction of a primary amine with ε‐caprolactone to give an amide carrying a terminal primary hydroxy group, followed by the enzymatic growth of the polymeric chain triggered by Novozym 435. This method is versatile and easy to handle and is suitable for the incorporation of different amines into polyesters, as has been shown with the model compounds benzylamine and tryptamine, the bioactive compound N‐deacetylthiocolchicine and the functionalized propargylamine and tyramine .
Rhodium and Iridium Nanoparticles Entrapped in Aluminum Oxyhydroxide Nanofibers: Catalysts for Hydrogenations of Arenes and Ketones at Room Temperature with Hydrogen Balloon
Authors: Park In Soo , Kwon Min Serk , Kang Kyung Yeon , Lee Jae Sung , Park Jaiwook
Published: August 2007

The recyclable metal nanoparticle catalysts, rhodium in aluminum oxyhydroxide [Rh/AlO(OH)] and iridium in aluminum oxyhydroxide [Ir/AlO(OH)], were simply prepared from readily available reagents. The catalysts showed high activities in the hydrogenation of various arenes and ketones under mild conditions. Selective hydrogenation was possible for bicyclic and tricyclic arenes in high yields. The catalysts were active at room temperature even with a hydrogen balloon. Also, the catalysts showed high turnover frequency (TOF) values under solventless conditions at 75 °C under 4 atm hydrogen pressure: ca. 1700 h−1 in the hydrogenation of benzene. Furthermore, Rh/AlO(OH) can be reused for at least 10 times without activity loss. The catalysts were characterized by the transmission electron microscopy (TEM), powder X‐ray diffraction (XRD), inductively coupled plasma (ICP), energy dispersive X‐ray analysis (EDX), X‐ray photoelectron spectroscopy (XPS), nitrogen adsorption and hydrogen chemisorption experiments. The sizes of rhodium and iridium particles were estimated to be 3–4 nm and 2–3 nm, respectively. Aluminum oxyhydroxide nanofibers of these catalysts have surface areas of 500–600 m2 g−1.