Effect of sample pre-cracking method and notch geometry in plane strain fracture toughness tests as applied to a PMMA resin

The influence of test method factors (notch shape, square or angular, and pre-cracking method, by tapping onto or pressing a razor blade) on the results obtained in plane strain fracture toughness test according to standard ASTM D5045 using SENB specimens made of a commercial PMMA resin were investigated. Results were analyzed quantitatively by comparing the obtained K-IC values and qualitatively by observing their effect on the Moire fringes observed using photoelasticity, showing that, at 95% significance level, the K-IC values are affected by the pre-cracking method, with the most conservative value being obtained when natural pre-cracks were introduced by tapping onto a razor blade (K-IC = 1.15 +/- 0.11 MPa.m(0.5)). This correlates with a perturbation in the stress field close to the pre-crack tip observed in the photoelasticity test sample when it was introduced by pressing the razor blade. Surprisingly, notch geometry only slightly affects the results. (C) 2012 Elsevier Ltd. All rights reserved.

Growth and nitrogen fixation in soybean treated with doses of composted sewage sludge

The use of sewage sludge is a highly promising practice for the development of sustainable agricultural systems. The objective of this study was to evaluate doses of sewage sludge composted with and without Rhizobium inoculation in leaf N content, nodule number, nodule dry weight and plant during flowering. The experiment was conducted in the greenhouse of the Department of Soil Science and Natural Resources College of Agricultural Sciences of Botucatu, using as substrate used in vessels of 30 liters a Red Yelow Latosol sandy texture with experimental design adopted was randomized blocks constituted for 10 treatments and five doses of composted sewage sludge (0, 10, 20, 30, 40 t ha(-1)) with or without inoculation Bradyrhizobium japonic with three replications. There was an increase in the number and dry weight of nodules and shoot dry mass of soybeans due to the increase of the dose of sludge up to a dose of 20 t ha(-1) and after this dose there was a decrease of these parameters. At a dose of 10 t ha(-1) sludge compost inoculated seeds showed higher for foliar concentrations of N and number of nodules compared with uninoculated seeds. At a dose of 30 t ha(-1) inoculated seeds were higher compared to uninoculated in all parameters.

Probabilistic crack growth analyses using a boundary element model: Applications in linear elastic fracture and fatigue problems

This paper addresses the numerical solution of random crack propagation problems using the coupling boundary element method (BEM) and reliability algorithms. Crack propagation phenomenon is efficiently modelled using BEM, due to its mesh reduction features. The BEM model is based on the dual BEM formulation, in which singular and hyper-singular integral equations are adopted to construct the system of algebraic equations. Two reliability algorithms are coupled with BEM model. The first is the well known response surface method, in which local, adaptive polynomial approximations of the mechanical response are constructed in search of the design point. Different experiment designs and adaptive schemes are considered. The alternative approach direct coupling, in which the limit state function remains implicit and its gradients are calculated directly from the numerical mechanical response, is also considered. The performance of both coupling methods is compared in application to some crack propagation problems. The investigation shows that direct coupling scheme converged for all problems studied, irrespective of the problem nonlinearity. The computational cost of direct coupling has shown to be a fraction of the cost of response surface solutions, regardless of experiment design or adaptive scheme considered. (C) 2012 Elsevier Ltd. All rights reserved.

Influence of Fixation Products Used in the Histological Processing in the FTIR Spectra of Lung Cells

The aim of the present study is to evaluate the differences on FTIR spectra of the normal lung cell (noncancerous mice lung epithelial cell line e10) due to different fixation protocols for histological processing. The results shown that formalin and methacarn (normally used in fixation) did cause many changes on the FTIR spectra of mice lung cells e10, mainly in the organic compounds (800-1800 cm(-1)) in lipids, DNA, and proteins, and the alcohol 70% fixation protocol caused almost no changes on the FTIR spectra compared to unfixed cells spectra (in PBS). It can be concluded that histological processing with alcohol 70% fixation protocol can be used in the FTIR study of mice lung cell line e10.

Tomographic, Histological, and Immunohistochemical Evidences on the Use of N-Butyl-2-Cyanoacrilate for Onlay Graft Fixation in Rabbits

Background: The bone tissue responses to Cyanoacrylate have been described in the literature, but none used N-butyl-2-cyanoacrilate (NB-Cn) for bone graft fixation. Purpose: The aims of the study were: (a) to analyze the bone grafts volume maintenance fixed either with NB-Cn or titanium screw; (b) to assess the incorporation of onlay grafts on perforated recipient bed; and (c) the differences of expression level of tartrate-resistant acid phosphatase (TRAP) protein involved in bone resorption. Materials and Methods: Eighteen New Zealand White rabbits were submitted to calvaria onlay grafting on both sides of the mandible. On one side, the graft was fixed with NB-Cn, while on the other hand the bone graft was secured with an osteosynthesis screw. The computed tomography (CT) was performed just after surgery and at animals sacrifice, after 1 (n = 9) and 6 weeks (n = 9), in order to estimate the bone grafts volume along the experiments. Histological sections of the grafted areas were prepared to evaluate the healing of bone grafts and to assess the expression of TRAP protein. Results: The CT scan showed better volume maintenance of bone grafts fixed with NB-Cn (p = 0.05) compared with those fixed with screws, in both experimental times (analysis of variance). The immunohistochemical evaluation showed that the TRAP expression in a 6-week period was significantly higher compared with the 1-week period, without showing significant difference between the groups (Wilcoxon and MannWhitney). Histological analysis revealed that the NB-Cn caused periosteum damage, but provided bone graft stabilization and incorporation similar to the control group. Conclusion: The perforation provided by screw insertion into the graft during fixation may have triggered early revascularization and remodeling to render increased volume loss compared with the experimental group. These results indicate that the NB-Cn possesses equivalent properties to titanium screw to be used as bone fixation material in osteosynthesis.

Fracture resistance of endodontically treated teeth restored with different intraradicular posts with different lengths

Aim: This study compared the resistance to fracture of endodontically treated teeth restored with different intraradicular posts with different lengths and full coverage metallic crowns. Methods: Sixty extracted human canine teeth were randomly divided into 6 groups. Groups CP5, CP75 and CP10 were restored using custom cast post and core (CP) and groups PF5, PF75 and PF10 were restored with provisional pre-fabricated tin post (PF) and composite resin core at 5 mm, 7.5 mm and 10 mm of intraradicular length, respectively. The specimens were submitted to dynamic cyclic loading and those that resisted to this load were submitted to load compression using a universal testing machine. Compressive load was applied at a 45-degree angle to the long axis of the tooth until failure. Results: Kruskal-Wallis one-way analysis of variance by ranks showed statistically significant differences among the groups (p<0.0001). However, when the means were compared using the Tukey’s test, significant differences were noted between groups CP5 and CP10 and between groups CP10 and PF5. All groups presented root fractures and post displacements during mechanical cycling. All teeth in groups CP5 and PF5 failed the dynamic cycling test. Conclusions: This study showed that increasing intraradicular post length also increases resistance to fracture of endodontically treated teeth. On the other hand, most endodontically treated teeth restored with pre-fabricated tin posts (provisional posts) failed in the dynamic cycling test

Distribution of nitrogen fixation and nitrogenase-like sequences amongst microbial genomes

Abstract Background The metabolic capacity for nitrogen fixation is known to be present in several prokaryotic species scattered across taxonomic groups. Experimental detection of nitrogen fixation in microbes requires species-specific conditions, making it difficult to obtain a comprehensive census of this trait. The recent and rapid increase in the availability of microbial genome sequences affords novel opportunities to re-examine the occurrence and distribution of nitrogen fixation genes. The current practice for computational prediction of nitrogen fixation is to use the presence of the nifH and/or nifD genes. Results Based on a careful comparison of the repertoire of nitrogen fixation genes in known diazotroph species we propose a new criterion for computational prediction of nitrogen fixation: the presence of a minimum set of six genes coding for structural and biosynthetic components, namely NifHDK and NifENB. Using this criterion, we conducted a comprehensive search in fully sequenced genomes and identified 149 diazotrophic species, including 82 known diazotrophs and 67 species not known to fix nitrogen. The taxonomic distribution of nitrogen fixation in Archaea was limited to the Euryarchaeota phylum; within the Bacteria domain we predict that nitrogen fixation occurs in 13 different phyla. Of these, seven phyla had not hitherto been known to contain species capable of nitrogen fixation. Our analyses also identified protein sequences that are similar to nitrogenase in organisms that do not meet the minimum-gene-set criteria. The existence of nitrogenase-like proteins lacking conserved co-factor ligands in both diazotrophs and non-diazotrophs suggests their potential for performing other, as yet unidentified, metabolic functions. Conclusions Our predictions expand the known phylogenetic diversity of nitrogen fixation, and suggest that this trait may be much more common in nature than it is currently thought. The diverse phylogenetic distribution of nitrogenase-like proteins indicates potential new roles for anciently duplicated and divergent members of this group of enzymes.

Increased vertebral morphometric fracture in patients with postsurgical hypoparathyroidism despite normal bone mineral density

Background In human malaria, the naturally-acquired immune response can result in either the elimination of the parasite or a persistent response mediated by cytokines that leads to immunopathology. The cytokines are responsible for all the symptoms, pathological alterations and the outcome of the infection depends on the reciprocal regulation of the pro and anti-inflammatory cytokines. IL-10 and IFN-gamma are able to mediate this process and their production can be affected by single nucleotide polymorphisms (SNPs) on gene of these cytokines. In this study, the relationship between cytokine IL-10/IFN-gamma levels, parasitaemia, and their gene polymorphisms was examined and the participation of pro-inflammatory and regulatory balance during a natural immune response in Plasmodium vivax-infected individuals was observed. Methods The serum levels of the cytokines IL-4, IL-12, IFN-gamma and IL-10 from 132 patients were evaluated by indirect enzyme-linked immunosorbent assays (ELISA). The polymorphism at position +874 of the IFN-gamma gene was identified by allele-specific polymerase chain reaction (ASO-PCR) method, and the polymorphism at position -1082 of the IL-10 gene was analysed by PCR-RFLP (PCR-Restriction Fragment Length Polymorphism). Results The levels of a pro- (IFN-gamma) and an anti-inflammatory cytokine (IL-10) were significantly higher in P. vivax-infected individuals as compared to healthy controls. The IFN-gamma levels in primoinfected patients were significantly higher than in patients who had suffered only one and more than one previous episode. The mutant alleles of both IFN-gamma and IL-10 genes were more frequent than the wild allele. In the case of the IFNG+874 polymorphism (IFN-gamma) the frequencies of the mutant (A) and wild (T) alleles were 70.13% and 29.87%, respectively. Similar frequencies were recorded in IL-10-1082, with the mutant (A) allele returning a frequency of 70.78%, and the wild (G) allele a frequency of 29.22%. The frequencies of the alleles associated with reduced production of both IFN-gamma and IL-10 were high, but this effect was only observed in the production of IFN-gamma. Conclusions This study has shown evidence of reciprocal regulation of the levels of IL-10 and IFN-gamma cytokines in P. vivax malaria, which is not altered by the presence of polymorphism in the IL-10 gene.

In vitro fracture resistance of glass-fiber and cast metal posts with different designs

PURPOSE: To evaluate the in vitro fracture resistance of roots with glass-fiber and metal dowels with different designs. METHODS: Fifty-endodontically treated maxillary central incisors were embedded in acrylic resin. Ten of them received only the coronary preparation, and the remaining forty were embedded (except for 4mm of the cervical area) after removing the clinical crowns. Specimens were divided into five groups (n=10): control (teeth with only coronary preparation), cylindrical cast dowel, conical cast dowel, cylindrical glass-fiber dowel and conical glass-fiber dowel. Specimens were subjected to an increasing compressive load (N) until fracture. RESULTS: ANOVA indicated significant difference (P<.05) among the groups, and the Tukey-Kramer´s test identified these differences. The control group (867±243 N) presented the highest values and was statistically similar to cylindrical glass-fiber dowel group (711±180 N). There is no significant difference among the metal dowel cylindrical (435±245 N) or conical (585±164 N) group and conical glass-fiber dowel (453±112 N). Cylindrical glass-fiber dowel (711±180 N) and conical cast dowel and core (585±164 N) groups had intermediate values and did not differ from each other. CONCLUSIONS: Cylindrical glass fiber dowels represent a viable alternative to the cast-metal dowel cylindrical or conical. Cylindrical glass fiber dowels also increase endodontically treated incisors' resistance to fracture.

Database of diazotrophs in global ocean: abundances, biomass and nitrogen fixation rates

[EN] Marine N2 fixing microorganisms, termed diazotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N2) to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems 5 and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic cell counts or qPCR 10 assays targeting the nifH genes) and N2 fixation rates. Biomass conversion factors are estimated based on cell sizes to convert  abundance data to diazotrophic biomass. The database is limited spatially, lacking large regions of the ocean especially in the Indian Ocean. The data are approximately log-normal distributed, and large variances exist in most sub-databases with non-zero values differing 5 to 8 orders of magnitude. 15 Lower mean N2 fixation rate was found in the North Atlantic Ocean than the Pacific Ocean. Reporting the geometric mean and the range of one geometric standard error below and above the geometric mean, the pelagic N2 fixation rate in the global ocean is estimated to be 62 (53–73) TgNyr−1 and the pelagic diazotrophic biomass in the global ocean is estimated to be 4.7 (2.3–9.6) TgC from cell counts and to 89 (40–20 200) TgC from nifH-based abundances. Uncertainties related to biomass conversion factors can change the estimate of geometric mean pelagic diazotrophic biomass in the global ocean by about ±70 %. This evolving database can be used to study spatial and temporal distributions and variations of marine N2 fixation, to validate geochemical estimates and to parameterize and validate biogeochemical models. The database is 25 stored in PANGAEA (http://doi.pangaea.de/10.1594/PANGAEA.774851).

Magnitude and controls of N2 fixation in the subtropical Northeast Atlantic

Programa de doctorado en Oceanografía

Significance of non‐sinking particulate organic carbon and dark CO2 fixation to heterotrophic carbon demand in the mesopelagic northeast Atlantic

[EN] It is generally assumed that sinking particulate organic carbon (POC) constitutes the main source of organic carbon supply to the deep ocean's food webs. However, a major discrepancy between the rates of sinking POC supply (collected with sediment traps) and the prokaryotic organic carbon demand (the total amount of carbon required to sustain the heterotrophic metabolism of the prokaryotes; i.e., production plus respiration, PCD) of deep-water communities has been consistently reported for the dark realm of the global ocean. While the amount of sinking POC flux declines exponentially with depth, the concentration of suspended, buoyant non-sinking POC (nsPOC; obtained with oceanographic bottles) exhibits only small variations with depth in the (sub)tropical Northeast Atlantic. Based on available data for the North Atlantic we show here that the sinking POC flux would contribute only 4–12% of the PCD in the mesopelagic realm (depending on the primary production rate in surface waters). The amount of nsPOC potentially available to heterotrophic prokaryotes in the mesopelagic realm can be partly replenished by dark dissolved inorganic carbon fixation contributing between 12% to 72% to the PCD daily. Taken together, there is evidence that the mesopelagic microheterotrophic biota is more dependent on the nsPOC pool than on the sinking POC supply. Hence, the enigmatic major mismatch between the organic carbon demand of the deep-water heterotrophic microbiota and the POC supply rates might be substantially smaller by including the potentially available nsPOC and its autochthonous production in oceanic carbon cycling models.

Funzionalizzazione della mandibola dopo ricostruzione con lembo libero rivascolarizzato di fibula "single strut". Al di là del deficit di verticalità.

Obiettivi: Valutare la modalità  più efficace per la riabilitazione funzionale del limbo libero di fibula "single strut", dopo ampie resezioni per patologia neoplastica maligna del cavo orale. Metodi: Da una casistica di 62 ricostruzioni microvascolari con limbo libero di fibula, 11 casi sono stati selezionati per essere riabilitati mediante protesi dentale a supporto implantare. 6 casi sono stati trattati senza ulteriori procedure chirurgiche ad eccezione dell'implantologia (gruppo 1), affrontando il deficit di verticalità  della fibula attraverso la protesi dentaria, mentre i restanti casi sono stati trattati con la distrazione osteogenetica (DO) della fibula prima della riabilitazione protesica (gruppo 2). Il deficit di verticalità  fibula/mandibola è stato misurato. I criteri di valutazione utilizzati includono la misurazione clinica e radiografica del livello osseo e dei tessuti molli peri-implantari, ed il livello di soddisfazione del paziente attraverso un questionario appositamente redatto. Risultati: Tutte le riabilitazioni protesiche sono costituite da protesi dentali avvitate su impianti. L'età  media è di 52 anni, il rapporto uomini/donne è di 6/5. Il numero medio di impianti inseriti nelle fibule è di 5. Il periodo massimo di follow-up dopo il carico masticatorio è stato di 30 mesi per il gruppo 1 e di 38.5 mesi (17-81) di media per il gruppo 2. Non abbiamo riportato complicazioni chirurgiche. Nessun impianto è stato rimosso dai pazienti del gruppo 1, la perdita media di osso peri-implantare registrata è stata di 1,5 mm. Nel gruppo 2 sono stati riportati un caso di tipping linguale del vettore di distrazione durante la fase di consolidazione e un caso di frattura della corticale basale in assenza di formazione di nuovo osso. L'incremento medio di osso in verticalità è stato di 13,6 mm (12-15). 4 impianti su 32 (12.5%) sono andati persi dopo il periodo di follow-up. Il riassorbimento medio peri-implantare, è stato di 2,5 mm. Conclusioni: Le soluzioni più utilizzate per superare il deficit di verticalità  del limbo libero di fibula consistono nell'allestimento del lembo libero di cresta iliaca, nel posizionare la fibula in posizione ideale da un punto di vista protesico a discapito del profilo osseo basale, l'utilizzo del lembo di fibula nella versione descritta come "double barrel", nella distrazione osteogenetica della fibula. La nostra esperienza concerne il lembo libero di fibula che nella patologia neoplastica maligna utilizziamo nella versione "single strut", per mantenere disponibili tutte le potenzialità  di lunghezza del peduncolo vascolare, senza necessità  di innesti di vena. Entrambe le soluzioni, la protesi dentale ortopedica e la distrazione osteogenetica seguita da protesi, entrambe avvitate su impianti, costituiscono soluzioni soddisfacenti per la riabilitazione funzionale della fibula al di là  del suo deficit di verticalità . La prima soluzione ha preso spunto dall'osservazione dei buoni risultati della protesi dentale su impianti corti, avendo un paragonabile rapporto corona/radice, la DO applicata alla fibula, sebbene sia risultata una metodica con un numero di complicazioni più elevato ed un maggior livello di riassorbimento di osso peri-implantare, costituisce in ogni caso una valida opzione riabilitativa, specialmente in caso di notevole discrepanza mandibulo/fibulare. Decisiva è la scelta del percorso terapeutico dopo una accurata valutazione di ogni singolo caso. Vengono illustrati i criteri di selezione provenienti dalla nostra esperienza.

Il trattamento delle fratture e lussazioni vertebrali nei piccoli animali

Treatment of spinal fracture and luxation in small animals Traumatic spinal injuries usually result from a mechanic trauma. Spinal facture and luxations generally occur in the junction between and more mobile parts of the spinal column: close to the skull, thorax and pelvis. Fractures may occur alone or in combination with luxation as fracture/luxation. When the fractures are not stable the best solution is the surgical fixation. Internal and external fixation are the surgical methods for the treatment of vertebral fractures and luxations. The authors report the treatment of 12 cases of thoracic and lumbar vertebral fractures and luxations in small animals using the screws/pins and Polymethylmethacrylate technique. The analysis of results is a contribute I the valutation of surgical technique and complications in the post-surgical period.