bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Initial Temperature and Tempering Medium on Thermal Tempering of Dental Porcelains
Authors: Hojjatie B. , Anusavice K.J. 
Published: November 2010

The objective of this study was to test the hypothesis that quenching of porcelain in silicone oil rather than in compressed air will significantly increase the flexure strength by reducing the potential for crack formation during transient cooling. A secondary hypothesis to be tested is that the initial tempering temperature can be reduced significantly below the porcelain maturing temperature of 982°C but well above Tg without a decrease in strength. Opaque-body porcelain disks, 16 mm in diameter and 2 mm in thickness, with a thermal contraction mismatch (Δα) of -1.5,0, and +3.2 ppm/°C were tempered from initial temperatures of 650, 750, 850, and 982°C in silicone oil with kinematic viscosities of 50,1000, and 5000 centistokes. Porcelain disks were also subjected to three cooling procedures in air: slow cooling in a furnace (SC), free convective cooling in a laboratory bench (FC), and tempering (T) by blasting the surface of body porcelain with air. The crack size induced by a Vickers microhardness indenter was measured within one minute after crack development. For determination of the influence of initial cooling temperature on biaxial flexure strength, six body porcelain disks (Δα = 0) were tempered in air from initial temperatures of 650, 750, 850, and 982°C. The mean crack size of specimens tempered in oil was significantly smaller (p ≤ 0.001) than that of specimens that were slowly-cooled or fast-cooled in air for all thermal contraction mismatch cases. For the same initial temperature, the compatible system (Δα = 0) yielded a smaller crack size compared with the other mismatch levels. For specimens tempered in air, an increase in initial tempering temperature from 650°C to 850°C produced a 34% increase in flexure strength (80.2 MPa to 107.6 MPa). However, increasing the initial tempering temperature from 850°C to 982°C resulted in only a 7% increase in the mean flexure strength. The results of this study indicate that tempering of dental porcelains in air or in silicone oil from an initial temperature ranging from 650 to 850°C improved the resistance to crack initiation and failure. However, compared with oil quenching, tempering in air was associated with a smaller risk of thermal shock failure.
A Histological Study of the Exfoliation of Human Deciduous Teeth
Authors: Sahara N. , Okafuji N. , Toyoki A. , Ashizawa Y. , Yagasaki H. , Deguchi T. , Suzuki K. 
Published: November 2010

For clarification of the histological details of the shedding of human deciduous teeth, exfoliated and extracted deciduous teeth were examined by light and electron microscopy. After the roots were completely resorbed, the dento-gingival junction migrated along the inner resorbing surface and finally reached the pulpal surface of the crown. At the same time, the gingival epithelium also proliferated and migrated under the crown of the deciduous tooth in such a way that part of it lined the residue of the pulp and another part lined the surface overlying the erupting successional tooth. This phenomenon took place from various sides of the tooth surface. Therefore, just before exfoliation, the migrated gingival epithelium formed narrow necks of tissue, and the crown was only superficially attached to the gingiva by them. The final shedding of the tooth appeared to occur by a tearing of these narrow tissue regions. The results of the present study suggest that the dento-gingival junction as well as gingival epithelium play important roles in the process of exfoliation of human deciduous teeth.
An in vitro and in vivo Study of the Release of Mercury Vapor from Different Types of Amalgam Alloys
Authors: Berglund A. 
Published: November 2010

The aim of the in vitro part of the study was to measure the rate of release of mercury vapor from different types of dental amalgam in air, and in air during cyclic dipping into isotonic saline solution or Fusayama solution. The measurements were carried out by means of the Mercollector/Mercometer system, based on atomic absorption spectrophotometry. Both new (age ∼ 2 months) and old (age ∼ 1.5 years) amalgam specimens were studied. The variations in the rate of release of mercury vapor in air during cyclic dipping into aqueous media were most pronounced during the first day of the 10-day period studied. In air during cyclic dipping into the aqueous media, the conventional amalgam specimens released mercury vapor at lower rates over the whole period than did the dispersed and single-composition types studied. The aim of the in vivo part of the study was to determine the daily release of mercury vapor from amalgam restorations made of alloys of the same types and batches as those used in the in vitro part of the study. A series of measurements was carried out on each of eight subjects before and after amalgam therapy. None of the subjects was occupationally exposed to mercury. The subjects had to follow a standardized schedule for 24 h, where they ate, drank, and brushed their teeth at predetermined times (Berglund, 1990). The amount of mercury vapor released per time unit was measured at intervals of 30-45 min. Samples of urine and saliva were analyzed for mercury. The average frequency of fish meals per month was noted. The amalgam therapy— i.e ., from 3 to 6 occlusal amalgam surfaces and from 3 to 10 surfaces in total-had very little influence on the intra-oral release of mercury vapor, regardless of amalgam type used, nor were any effects found on mercury levels in urine and saliva.
An in vitro and in vivo Study of Toothbrush Bristle Splaying
Authors: Rawls H.R. , Casella R. , Mkwayi-Tulloch N.J. 
Published: November 2010

The extent to which a toothbrush is worn out, as evidenced by bristle splaying, is an important determinant of cleaning efficacy. In order for this aspect of oral hygiene to be studied, an accelerated means of producing a life-like pattern of bristle splaying was investigated and compared with splaying induced by a human test-panel. Porcelain denture teeth were brushed under a static applied load in a slurry of dentifrice, by means of a revolving "figure 8" motion, for up to 12,000 revolutions. This was found to induce an increase in the degree of splaying (as measured by "wear index") that was well-fitted (R2 = 0.96) by a second-order expression of the form: where WI = wear index, WIi = initial wear index, Ri = initial rate of increase in WI, tj = brushing time measured in either machine revolutions (tr) or weeks of human use (tw), and C = a separate constant for each brushing mode (machine or human panel). The rate of splaying was found to be strongly influenced by the quality of the bristle filament, but not by small differences in toothbrush design. The splaying pattern induced by the machine could not be distinguished visually from that in a set of brushes used at home by human volunteers. A strong correlation was found between the splaying produced by machine-brushing and by a panel who brushed free-style at home for 13 weeks. The data fit a linear correlation function: These results demonstrate that an accelerated brushing method can mimic the human process involved in toothbrush splaying, that a quantitative relationship exists between the two, and that it is sensitive to brush-construction factors known to affect splaying. This method is therefore suitable for use in investigations concerning toothbrush durability and the effects of toothbrush design and use on various aspects of oral health.
The Effect of the Electrode Potential on the Release of Mercury from Dental Amalgam
Authors: Marek M. 
Published: November 2010

The effect of the electrode potential on the rate of mercury dissolution from the matrix phase (γ1) of dental amalgam was investigated. Specimens of the Ag-Hg phase, with and without dissolved tin, were exposed to synthetic saliva and maintained at various potentials by means of a potentiostat. The amount of dissolved mercury was determined after 24 h by cold-vapor Atomic Absorption Spectrophotometry. Anodic polarization curves for the γ1 specimens and pure silver and mercury were also recorded. The results for the Ag-Hg phase showed a potential-independent dissolution rate between -0.6 and -0.1 V (SCE), followed by a sharp increase. Mercury dissolution from the Ag-Hg-Sn phase was much slower than from the tin-free γ 1 phase, and potential-independent to +0.05 V (SCE); a sharp increase in mercury dissolution was observed at +0.1 V (SCE). The anodic polarization curves for the Ag-Hg-Sn phase indicated passivity between -0.67 V and +0.1 V (SCE), but no clear passivation for the Ag-Hg specimen, silver, or mercury. The results show that in the potential-independent region, mercury dissolved in the atomic form from both the tin-free and tin-containing γ1 phase. The increase in dissolution in the upper range of potentials was tentatively attributed to selective anodic dissolution of silver and an onset of electrochemical dissolution. The results indicate that the rate of mercury release from the γ 1 phase of dental amalgam was not affected by potential changes due to alloying or galvanic contacts unless the potential exceeded some critical value.
Enhanced Chemical Strengthening of Feldspathic Dental Porcelain
Authors: Denry I.L. , Rosenstiel S.F. , Holloway J.A. , Niemiec M.S. 
Published: November 2010

Previous studies on ion exchange of dental ceramics have shown that the biaxial flexural strength can be improved by exchanging potassium for sodium ions at temperatures below the strain point. The rubidium ion is bigger than the potassium ion and can also be considered as a candidate for replacing smaller ions, i.e., sodium or potassium, although it has not been used for dental ceramics. The double-step method uses the exchange of a small ion for a large ion (Li for Na) above the strain point, and the further exchange of a large ion for a small ion (K for Li) below the strain point. The purpose of this study was to compare the effect of rubidium-for-potassium ion exchange with that of potassium-for-sodium exchange (Tuf-Coat, G-C International Corp., Japan) on the flexural strength of a feldspathic dental porcelain and to test the hypothesis that a double-step ion exchange can lead to greater strengthening than potassium ion exchange alone. Weight measurements were performed before and after treatment. Qualitative chemical analyses allowed the rubidium, potassium, and sodium concentration profiles to be determined along cross-sections of the specimens. The maximum biaxial stresses were calculated after specimens were fractured in water on a ball-on-ring fixture at 0.5 mm/min. Relative to the untreated control group, the flexural strength of the potassium-exchanged groups was significantly increased, except for those treated at 400 or 500°C. All the groups treated with RbNO3 exhibited a significant increase in flexural strength, with a maximum for the group treated at 450°C. The group submitted to a double-step exchange showed a statistically significant increase in the mean flexural strength compared with the group treated with Tuf-Coat at 450°C.
Electronic Structures of Tungsten and Molybdenum Carbides as a Fuel Cell Anode Catalyst
Authors: Tominaga Hiroyuki , Nagai Masatoshi 
Published: November 2010

Abstract
The band structures of W2C(001), WC(001), β-Mo2C(001), and Pt(111) slabs as an anode catalyst with two adsorbed hydrogen molecules using periodic DFT calculations revealed the anode performance of the carbides.
Cyclic and Linear Structures Constructed by Ionic Bonds between Alkali Ion and Pinwheel Pentanuclear [GdIII(CuIIL)4] Core of M[GdIII(CuIIL)4] (M+ = Na+, K+, and Cs+; H3L = N-(4-Methyl-6-oxo-3-azahept-4-enyl)oxamic Acid)
Authors: Maruno Yuji , Yabe Kazuya , Hagiwara Hiroaki , Fujinami Takeshi , Matsumoto Naohide , Re Nazzareno , Mrozinski Jerzy 
Published: November 2010

Abstract
Three copper(II)–gadolinium(III) complexes M[Gd(CuL)4] with M+ = Na+, K+, and Cs+ have been synthesized, where H3L denotes N-(4-methyl-6-oxo-3-azahept-4-enyl)oxamic acid. The anionic part [Gd(CuL)4]− assumes a pinwheel-like pentanuclear GdCu4 core and the central GdIII ion is coordinated by eight oxygen atoms of four “(CuL),” where each “(CuL)” assumes a square-planar N2O2 coordination geometry and functions as a bidentate chelate ligand to GdIII ion. The sodium and potassium salts assume a one-dimensional (1D) chain structure bridged by Na+ or K+ ions, while the cesium salt assumes a cyclic dimeric structure bridged by Cs+ ions. For the assembly structures, the cation acts as a connector between adjacent [Ln(CuL)4]− cores. The magnetic data demonstrated an intracluster ferromagnetic interaction between GdIII and CuII ions within a GdCu4 core and an intercluster antiferromagnetic interaction through the cation. The magnetic susceptibilities can be reproduced by the spin Hamiltonian based on the pentanuclear GdCu4 structure, = βH(4gCuSCu + gGdSGd) − 2JSGd(SCu1 + SCu2 + SCu3 + SCu4). The best-fit parameters are gGd = 2.00, gCu = 2.12, JGd–Cu = +1.11 cm−1, zJ′ = −0.065 cm−1, and 0.4% of monomeric CuII impurity for the Na+ salt,; gGd = 2.00, gCu = 2.13, JGd–Cu = +1.03 cm−1, zJ′ = −0.038 cm−1, and 0.2% of monomeric CuII impurity for the K+ salt,; and gGd = 2.00, gCu = 2.14, JGd–Cu = +0.67 cm−1, zJ′ = −0.025 cm−1, 0.2% of monomeric CuII impurity for the Cs+ salt. The Gd–Cu coupling constant J is very similar in the Na+ and K+ salts (+1.11 and +1.03 cm−1) but is slightly smaller for the Cs+ salt (+0.67 cm−1), probably due to the different packing of the GdCu4 clusters in the latter salt (cyclic dimers instead of an infinite chain); (2) the intercluster antiferromagnetic interaction, responsible for the low temperature decrease of χMT, significantly decreases when the ionic radius of the alkali cation increases (Na+ &lt; K+ &lt; Cs+) thus keeping the pentanuclear units further apart.
Development of Highly Selective Organic Reactions Catalyzed by Designed Amine Organocatalysts
Authors: Kano Taichi , Maruoka Keiji 
Published: November 2010

Abstract
A series of chiral amines with conceptually new design have been developed as chiral organocatalysts. These chiral amine organocatalysts have been successfully applied to several asymmetric reactions via iminium and enamine intermediates and exhibited unique reactivity and selectivity in comparison with previous amine organocatalysts derived from naturally occurring amino acids. The synthetic utility of these asymmetric organocatalytic reactions has also been demonstrated in their application to the synthesis of versatile chiral building blocks.
Eine fluidisch angetriebene anthropomorphe Roboterhand
Authors: Werner Tino , Kargov Artem , Gaiser Immanuel , Bierbaum Alexander , Schill Julian , Schulz Stefan , Bretthauer Georg 
Published: November 2010

Zusammenfassung
In diesem Artikel wird eine fluidisch angetriebene Roboterhand vorgestellt, deren flexible Aktuatoren adaptives Greifen sowie die weiche Handhabung von Gegenständen ermöglichen. Der mechanische Aufbau vereinigt die anthropomorphe Erscheinung mit einer präzisen DreiPunkt-Kinematik eines Greifers. Es werden Designmerkmale, das Antriebskonzept, die Steuerungskomponenten, technische Eigenschaften und ein Anwendungsbeispiel für die Service-Robotik beschrieben.
Algorithmen zum Automatischen Erlernen von Motorfähigkeiten
Authors: Peters Jan , Kober Jens , Schaal Stefan 
Published: November 2010

Zusammenfassung
Das automatische Erlernen von Motorfähigkeiten würde es einem autonomen Roboter ermöglichen, sich an neuartige Situationen anzupassen. Dieses Ziel ist seit langem eine Vision der Robotik, Künstlichen Intelligenz und Kognitionswissenschaft. Allerdings kann dieses Vorhaben mit heutigen Techniken nicht erreicht werden, da nur wenige der Methoden in der Lage sind, mit der Komplexität moderner Manipulatoren oder von humanoiden Robotern umzugehen. Dieser Artikel beschreibt allgemeine Ansätze für textslPolicy Learning mit einem Schwerpunkt auf Motorstrategien. Das Ziel ist es, die Grundlagen zu schaffen, um motorische Fähigkeiten zu erlernen und sich selber automatisch zu verbessern. Hierfür werden zwei bedeutende Bereiche für einen solchen Ansatz betrachtet: einerseits Policy-Learning-Algorithmen, die den Anforderungen des Erwerbens motorischer Fähigkeiten gerecht werden, andererseits theoretisch fundierte, allgemeine Strukturen, welche für Aufgabendarstellung und -ausführung benötigt werden.
Early Risk Factors for Persistent Anemia After Kidney Transplantation
Authors: Schonder Kristine S. , Corman Shelby L. , Hung Whitney 
Published: November 2010

Study Objective. To identify predictors of persistent posttransplant anemia that appear within the first week after kidney transplantation in order to determine the high‐risk patients who might receive the most benefit from erythropoiesis‐stimulating agents.Study Design. Retrospective cohort study.Setting. University‐affiliated hospital and outpatient clinic.Patients. One hundred sixty‐four adult kidney transplant recipients (January 1, 2002‐June 30, 2007) with anemia on posttransplant day 7 who were followed at the clinic for at least 2 months after transplantation.Measurements and Main Results. Data from deidentified electronic medical records of the kidney transplant recipients were collected and included demographic characteristics, primary cause of renal failure, pertinent laboratory data, and donor information. To detect early predictors of persistent anemia, patients with persistent posttransplant anemia, defined as a hemoglobin level below 11 g/dl for 2 months (day 60) after transplantation, were compared with those who had nonpersistent posttransplant anemia, defined as a hemoglobin level below 11 g/dl on day 7 but 11 g/dl or greater on day 60. Of the 164 patients classified as having anemia on posttransplant day 7, 39 (23.8%) had persistent posttransplant anemia on day 60. In univariate analyses, hemoglobin level of 9 g/dl or below on day 7, donor age younger than 10 years, and female sex were variables associated with increased risk of persistent posttransplant anemia. In a multivariate analysis, donor age younger than 10 years was the most significant predictor of persistent posttransplant anemia, followed by hemoglobin level of 9 g/dl or below.Conclusion. Patients receiving transplants from donors younger than 10 years and those with hemoglobin levels of 9 g/dl or below on postoperative day 7 were found to be at highest risk for persistent posttransplant anemia and may receive the most benefit from early initiation of erythropoiesis‐stimulating agent therapy. In most of the kidney transplant recipients, posttransplant anemia resolved without the use of these agents.
Differences in Clinical Outcomes in Patients with Vancomycin‐Resistant Enterococci According to Linezolid Susceptibility
Authors: Scheetz Marc H. , Knechtel Stephanie A. , Postelnick Michael J. , Malczynski Michael , Qi Chao 
Published: November 2010

Study Objective. To evaluate the differences in clinical outcomes in patients with linezolid‐intermediate or ‐resistant vancomycin‐resistant enterococci (LIRVRE) isolates, as defined by the presence of the G2576T mutation, compared with patients who had linezolid‐susceptible VRE (LSVRE) isolates in order to further discern the clinical relevance of linezolid resistance associated with this mutation.Design. Retrospective cohort study.Setting. Large tertiary care academic medical center.Patients. Eighteen adults (mean age 55.4 yrs) with LIRVRE (case patients) who were frequency matched to 54 adults (mean age 58.1 yrs) with LSVRE (control patients) in a 1:3 ratio based on site of culture and VRE species.Measurements and Main Results. Linezolid resistance was determined by phenotype and genotype (G2576T mutation by polymerase chain reaction). Patients with LIRVRE received more linezolid before isolation of the organism than did those with LSVRE (mean 8.6 vs 0.2 days, p<0.001). No difference in mortality was found; however, compared with controls, patients with LIRVRE were more likely to be transferred to the intensive care unit (56% vs 28%, p=0.032), had more surgical procedures for VRE (39% vs 15%, p=0.029), and had more echocardiograms performed (44% vs 19%, p=0.028) as a result of their VRE. Multivariate analysis revealed that surviving case patients had an increased duration of culture positivity of approximately 1.5 days (p=0.049) and a near statistically significant increase of postculture length of stay of approximately 2 days (p=0.053).Conclusion. The clinical relevance of the G2576T mutation among enterococci remains unclear; however, the increased morbidity and resource utilization among patients with LIRVRE is a finding of concern. Careful monitoring of genotypically confirmed LIRVRE emergence and ongoing epidemiologic studies will be critical to better characterize the clinical relevance of linezolid resistance.
Psychological Distress as a Negative Survival Factor for Patients with Hematologic Malignancies Who Underwent Allogeneic Hematopoietic Stem Cell Transplantation
Authors: Park Ji Eun , Kim Kyung Im , Yoon Sung Soo , Hahm Bong Jin , Lee Sang Min , Yoon Jeong Hyun , Shin Wan Gyoon , Lee Hye Suk , Oh Jung Mi 
Published: November 2010

Study Objective. To evaluate the influence of distress on overall survival of patients with hematologic malignancies who underwent allogeneic stem cell transplantation (allo‐SCT) and to analyze the possible risk factors for death.Design. Retrospective cohort study.Setting. Large tertiary care teaching hospital.Patients. Seventy‐seven patients (aged ≥ 15 yrs) with hematologic malignancies who underwent allo‐SCT between January 2000 and August 2007; 20 patients with distress history were matched in a 1:3 ratio with 57 patients without distress history.Measurements and Main Results. The primary outcome was overall survival, defined as the time from allo‐SCT to disease‐related death or last date of follow‐up. Secondary outcomes were time to hematologic recovery (absolute neutrophil count ≥ 500 cells/mm3) from day of allo‐SCT, length of hospital stay, and opioid usage. Sociodemographic information and clinical characteristics were analyzed for possible risk factors. Patient history of psychological distress resulted in a significantly higher mortality rate in the first year after allo‐SCT (hazard ratio [HR] 3.05, 95% confidence interval [CI] 1.48–6.28, p=0.001) and led to a shorter overall survival rate (HR 1.63, 95% CI 0.86–3.10, p=0.133). However, psychological distress had no effect on hospital length of stay, hematologic recovery time, opioid usage status, or dose of opioid analgesics used. Factors associated with death after allo‐SCT in the univariate analysis (p<0.05) were high‐relapse risk disease, umbilical cord blood SCT, total‐body irradiation‐containing conditioning regimen, and higher educational background. In the multivariate analysis, high relapse risk (HR 3.85, 95% CI 1.81–8.20, p<0.001) and total‐body irradiation‐containing conditioning regimen (HR 3.50, 95% CI 1.29–9.51, p=0.01) were identified as risk factors for death.Conclusion. A history of psychological distress before allo‐SCT, after adjusting for other patient‐ and disease‐related prognostic factors, had a significant influence on early death in the first year after transplantation.