On the catalytic hydrogenation of polycyclic aromatic hydrocarbons into less toxic compounds by a facile recoverable catalyst

Here we present the catalytic hydrogenation of polycyclic aromatic hydrocarbons (PAHs) to less toxic mixtures of saturated and partial unsaturated polycyclic hydrocarbons under mild reaction conditions using a magnetically recoverable rhodium catalyst and molecular hydrogen as the exclusive H source. The catalyst is easily recovered after each reaction by placing a permanent magnet on the reactor wall and it can be reused in successive runs without any significant loss of catalytic activity. As an example, anthracene was totally converted into the saturated polycyclic hydrocarbon form (ca. 60%) and the partially hydrogenated form, 1,2,3,4,5,6,7,8-octahydroanthracene (ca. 40%). The catalyst operates in a broad range of temperature and H(2) pressure in both organic and aqueous/organic solutions of anthracene and it also exhibits significant activity at low substrate concentrations (20 ppm). This can be an efficient recycling process for hydrogenation of PAHs present in contaminated fluid waste streams. (C) 2009 Elsevier B.V. All rights reserved.

Microstructure and Mineral Composition of Dental Enamel of Permanent and Deciduous Teeth

Purpose: This study evaluated and compared in vitro the microstructure and mineral composition of permanent and deciduous teeth`s dental enamel. Methods: Sound third molars (n = 12) and second primary molars (n = 12) were selected and randomly assigned to the following groups, according to the analysis method performed (n = 4): Scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Energy dispersive X-ray spectrometer (EDS). Qualitative and quantitative comparisons of the dental enamel were done. The microscopic findings were analyzed statistically by a nonparametric test (Kruskal-Wallis). The measurements of the prisms number and thickness were done in SEM photomicrographs. The relative amounts of calcium (Ca) and phosphorus (P) were determined by EDS investigation. Chemical phases present in both types of teeth were observed by the XRD analysis. Results: The mean thickness measurements observed in the deciduous teeth enamel was 1.14 mm and in the permanent teeth enamel was 2.58 mm. The mean rod head diameter in deciduous teeth was statistically similar to that of permanent teeth enamel, and a slightly decrease from the outer enamel surface to the region next to the enamel-dentine junction was assessed. The numerical density of enamel rods was higher in the deciduous teeth, mainly near EDJ, that showed statistically significant difference. The percentage of Ca and P was higher in the permanent teeth enamel. Conclusions: The primary enamel structure showed a lower level of Ca and P, thinner thickness and higher numerical density of rods. Microsc. Res. Tech. 73:572-577, 2010. (C) 2009 Wiley-Liss. Inc.

Scanning Electron Microscopic Preliminary Study of the Efficacy of SmearClear and EDTA for Smear Layer Removal after Root Canal Instrumentation in Permanent Teeth

This study aimed to evaluate the efficacy of SmearClear (SybronEndo, Orange, CA) and EDTA for smear layer removal from root canals of permanent teeth after instrumentation. Thirty extracted human permanent teeth (n = 10) were randomly assigned to the following groups: group 1 = 14.3% EDTA, group 2 = SmearClear, and group 3 = no smear layer removal procedure was undertaken (control). The specimens were submitted to scanning electron microscopy analysis. Magnifications of 200x and 750x were used to evaluate cleaning at the apical, middle, and cervical thirds according to a three-point scoring system. Data were analyzed statistically by the Mann-Whitney U test (5% significance level). Groups 1 and 2 differed significantly from group 3 (p < 0.01). However, there was no statistically significant difference (p > 0.05) between groups 1 and 2. In conclusion, SmearClear was able to remove the smear layer from the root canals of permanent teeth similarly as 14.3% EDTA, suggesting that both solutions may be indicated for such purpose. (J Endod 2008,34:1541-1544)

Arrest of root formation in a permanent maxillary central incisor subsequent to trauma and pulp necrosis to the primary predecessor

This paper reports a case in which a previous traumatic injury at the age of 2 and pulp necrosis to a primary incisor resulted in a rare injury to the permanent successor tooth. The radiographic examination at the age of 9 showed the arrest of root formation of the permanent maxillary right central incisor, which did not erupt. Tooth 11 was extracted and a functional removable space maintainer was prepared. At the age of 17, the patient received an anterior fixed prosthesis for re-establishment of the esthetics, phonetics and deglutition.

Tooth Abnormalities of Number and Position in the Permanent Dentition of Patients With Complete Bilateral Cleft Lip and Palate

Objective: To radiographically evaluate the prevalence of tooth abnormalities of number and position in the permanent dentition of individuals with complete bilateral cleft lip and palate. Design: Cross-sectional retrospective. Setting: Hospital for Rehabilitation of Craniofacial Anomalies, University of Sao Paulo, Bauru, Brazil. Patients: Two hundred five individuals with complete bilateral cleft lip and palate. Interventions: Analysis of patient records and panoramic radiographs. Main outcome measures: Evaluation of hypodontia and supernumerary teeth and analysis of the position of the permanent maxillary lateral incisor in relation to the alveolar cleft. Results: Hypodontia was observed in 144 patients (70.2%), and the highest prevalence was observed for the maxillary lateral incisor. When both lateral incisors were present (43%), they were primarily located on the distal side of the cleft (25%). Supernumerary teeth were observed in 11.7% of individuals. Conclusion: Patients with cleft lip and palate presented high prevalence of hypodontia and supernumerary teeth. The prevailing characteristics of their location may suggest the presence of a similar genetic component for the occurrence of hypodontia and cleft.

Dental anomalies of number in the permanent dentition of patients with bilateral cleft lip: Radiographic study

Objective: To radiographically evaluate the prevalence of dental anomalies in patients with complete and incomplete bilateral cleft lip, comparing the prevalence of anomalies between genders and cleft types. Setting: Hospital for Rehabilitation of Craniofacial Anomalies, University of Sao Paulo (HRAC/USP), Bauru, Sao Paulo, Brazil. Participants: 150 randomly selected panoramic radiographs of individuals with complete or incomplete bilateral cleft lip; patient age 12 to 25 years (mean age 13.8 years). Results: Data were statistically analyzed to compare the possible association between presence of hypodontia and supernumerary teeth, according to gender and cleft type. Among the 150 patients evaluated, 80 (53.3%) were male and 70 (46.6%) were female. Since no statistically significant difference was found in hypodontia between genders, data were grouped for analysis, revealing prevalence of 31.6% for complete clefts and 26.8% for incomplete clefts. Concerning supernumerary teeth, the prevalence for the male patients was 28.2% for complete cleft lip and 29.2% for incomplete cleft lip. For female patients, the prevalence was significantly (p = .006) lower for complete cleft lip (17.5%) than for incomplete cleft lip (46.6%). Conclusions: The present results suggest that the prevalence of hypodontia was higher in patients with complete cleft lip, and the prevalence of supernumerary teeth was higher in patients with incomplete cleft lip, in agreement with previous studies.

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 May 2009-31 July 2009

This article documents the addition of 512 microsatellite marker loci and nine pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Alcippe morrisonia morrisonia, Bashania fangiana, Bashania fargesii, Chaetodon vagabundus, Colletes floralis, Coluber constrictor flaviventris, Coptotermes gestroi, Crotophaga major, Cyprinella lutrensis, Danaus plexippus, Fagus grandifolia, Falco tinnunculus, Fletcherimyia fletcheri, Hydrilla verticillata, Laterallus jamaicensis coturniculus, Leavenworthia alabamica, Marmosops incanus, Miichthys miiuy, Nasua nasua, Noturus exilis, Odontesthes bonariensis, Quadrula fragosa, Pinctada maxima, Pseudaletia separata, Pseudoperonospora cubensis, Podocarpus elatus, Portunus trituberculatus, Rhagoletis cerasi, Rhinella schneideri, Sarracenia alata, Skeletonema marinoi, Sminthurus viridis, Syngnathus abaster, Uroteuthis (Photololigo) chinensis, Verticillium dahliae, Wasmannia auropunctata, and Zygochlamys patagonica. These loci were cross-tested on the following species: Chaetodon baronessa, Falco columbarius, Falco eleonorae, Falco naumanni, Falco peregrinus, Falco subbuteo, Didelphis aurita, Gracilinanus microtarsus, Marmosops paulensis, Monodelphis Americana, Odontesthes hatcheri, Podocarpus grayi, Podocarpus lawrencei, Podocarpus smithii, Portunus pelagicus, Syngnathus acus, Syngnathus typhle,Uroteuthis (Photololigo) edulis, Uroteuthis (Photololigo) duvauceli and Verticillium albo-atrum. This article also documents the addition of nine sequencing primer pairs and sixteen allele specific primers or probes for Oncorhynchus mykiss and Oncorhynchus tshawytscha; these primers and assays were cross-tested in both species.

A Hopping Mechanism for Cargo Transport by Molecular Motors on Crowded Microtubules

Most models designed to study the bidirectional movement of cargos as they are driven by molecular motors rely on the idea that motors of different polarities can be coordinated by external agents if arranged into a motor-cargo complex to perform the necessary work Gross, Hither and yon: a review of bidirectional microtubule-based transport (Gross in Phys. Biol. 1:R1-R11, 2004). Although these models have provided us with important insights into these phenomena, there are still many unanswered questions regarding the mechanisms through which the movement of the complex takes place on crowded microtubules. For example (i) how does cargo-binding affect motor motility? and in connection with that-(ii) how does the presence of other motors (and also other cargos) on the microtubule affect the motility of the motor-cargo complex? We discuss these questions from a different perspective. The movement of a cargo is conceived here as a hopping process resulting from the transference of cargo between neighboring motors. In the light of this, we examine the conditions under which cargo might display bidirectional movement even if directed by motors of a single polarity. The global properties of the model in the long-time regime are obtained by mapping the dynamics of the collection of interacting motors and cargos into an asymmetric simple exclusion process (ASEP) which can be resolved using the matrix ansatz introduced by Derrida (Derrida and Evans in Nonequilibrium Statistical Mechanics in One Dimension, pp. 277-304, 1997; Derrida et al. in J. Phys. A 26: 1493-1517, 1993).

The dynamics of cargo driven by molecular motors in the context of asymmetric simple exclusion processes

We consider the dynamics of cargo driven by a collection of interacting molecular motors in the context of ail asymmetric simple exclusion process (ASEP). The model is formulated to account for (i) excluded-volume interactions, (ii) the observed asymmetry of the stochastic movement of individual motors and (iii) interactions between motors and cargo. Items (i) and (ii) form the basis of ASEP models and have already been considered to study the behavior of motor density profile [A. Parmeggiani. T. Franosch, E. Frey, Phase Coexistence in driven one-dimensional transport, Phys. Rev. Lett. 90 (2003) 086601-1-086601-4]. Item (iii) is new. It is introduced here as an attempt to describe explicitly the dependence of cargo movement on the dynamics of motors in this context. The steady-state Solutions Of the model indicate that the system undergoes a phase transition of condensation type as the motor density varies. We study the consequences of this transition to the behavior of the average cargo velocity. (C) 2009 Elsevier B.V. All rights reserved.

First-order-reversal-curve analysis of Pr-Fe-B-based nanocomposites

Ribbons of nominal composition (Pr(9.5)Fe(84.5)B(6))(0.96)Cr(0.01)(TiC)(0.03) were produced by arc-melting and melt-spinning the alloys on a Cu wheel. X-ray diffraction reveals two main phases, one based upon alpha-Fe and the other upon Pr(2)Fe(14)B. The ribbons show exchange spring behavior with H(c)=12.5 kOe and (BH)(max)= 13.6 MGOe when these two phases are well coupled. Transmission electron microscopy revealed that the coupled behavior is observed when the microstructure consists predominantly of alpha-Fe grains(diameter similar to 100 nm.) surrounded by hard material containing Pr(2)Fe(14)B. A first-order-reversal-curve (FORC) analysis was performed for both a well-coupled sample and a partially-coupled sample. The FORC diagrams show two strong peaks for both the partially-coupled sample and for the well coupled material. In both cases, the localization of the FORC probability suggests demagnetizing interactions between particles. Switching field distributions were calculated and are consistent with the sample microstructure. (C) 2009 Elsevier B.V. All rights reserved.