Effect of implantoplasty on the elastic limit of dental implants of different diameters

Background Implantoplasty reduces both implant diameter and the thickness of its walls, subsequently reducing the ability of the implant to resist fracture in response to functional load. In combination with an increase in the crown-implant ratio due to bone loss, this could increase the lever effect, which in presence of high masticatory forces or parafunctional habits, could lead to complications such as fracture of the implant or loosening of the prosthetic screw. Objectives To determine the elastic limits of internal connection, dental implants of different designs and diameters after an implantoplasty. Materials and methods This in vitro study included 315 tapered internal connection titanium dental implants, the threads of which were removed with an industrial milling machine-for standardized implantoplasty (IMP1; n = 105)-or with the conventional approach-manually, using high-speed burs (IMP2; n = 105). The remaining 105 implants were used as controls. The final implant diameters were recorded. The quality of the newly polished surfaces was assessed by scanning electron microscopy. All implants were subjected to a mechanical pressure resistance test. A Tukey''s test for multiple comparisons was used to detect differences in the elastic limit and final implant diameters between the implant groups. Results There were statistically significant differences in the elastic limit between the IMP1, IMP2, and control groups (p < 0.05). Furthermore, the implant diameter was significantly smaller in the IMP1 and IMP2 groups (p < 0.05). Scanning electron microscopy revealed smooth implant surfaces in the IMP1 and IMP2 groups, with some titanium particles visible in the IMP1 group. Conclusions Implantoplasty significantly decreased the elastic limit of internal connection titanium dental implants, especially in those with a smaller diameter (3-3.5 mm)

Characterization of IHF Binding to DNA Four-Way Junctions and Forks

The objective of the study is to characterise the mechanical properties of Ti-15Zr binary alloy dental implants and to describe their biomechanical behaviour as well as their osseointegration capacity compared with the conventional Ti-6Al-4V (TAV) alloy implants. The mechanical properties of Ti-15Zr binary alloy were characterised using Roxoli

Final Pre-40S Maturation Depends on the Functional Integrity of the 60S Subunit Ribosomal Protein L3

Ribosomal protein L3 is an evolutionarily conserved protein that participates in the assembly of early pre-60S particles. We report that the rpl3[W255C] allele, which affects the affinity and function of translation elongation factors, impairs cytoplasmic maturation of 20S pre-rRNA. This was not seen for other mutations in or depletion of L3 or other 60S ribosomal proteins. Surprisingly, pre-40S particles containing 20S pre-rRNA form translation-competent 80S ribosomes, and translation inhibition partially suppresses 20S pre-rRNA accumulation. The GTP-dependent translation initiation factor Fun12 (yeast eIF5B) shows similar in vivo binding to ribosomal particles from wild-type and rpl3[W255C] cells. However, the GTPase activity of eIF5B failed to stimulate processing of 20S pre-rRNA when assayed with ribosomal particles purified from rpl3[W255C] cells. We conclude that L3 plays an important role in the function of eIF5B in stimulating 3′ end processing of 18S rRNA in the context of 80S ribosomes that have not yet engaged in translation. These findings indicate that the correct conformation of the GTPase activation region is assessed in a quality control step during maturation of cytoplasmic pre-ribosomal particles

Presencia de los inmigrantes españoles en la economía de la región de Santiago de Cuba (1902- 1940)

Los inmigrantes españoles tuvieron una activa participación en la economía de la región de Santiago de Cuba aunque no pudieron competir con los monopolios norteamericanos en sectores claves como la industria azucarera, la minería, las finanzas y los ferrocarriles; por lo que concentraron sus inversiones en el comercio, las manufacturas y la producción de bebidas, alimentos, confituras y otros artículos

Carbon adsorbents for CO2 capture from bio-hydrogen and biogas streams: Breakthrough adsorption study

The biological production of H2 by dark fermentation is being extensively investigated due to the great potential of the two-phase hydrogen/methane fermentation process for recovering energy from carbohydrate-rich wastes. However, the purification of the bio-hydrogen and biogas obtained is needed to produce high-purity H2 and CH4 streams appropriate for industrial application. In this study, the performance of three activated carbons (No1KCla-600, No1KClb-1000 and No2OS-1000), synthesized from phenol–formaldehyde resins, as potential adsorbents for CO2 capture from bio-hydrogen and biogas streams has been evaluated under dynamic conditions. Adsorption–desorption cycles by means of temperature swings were conducted at ambient temperature and atmospheric pressure with CO2/H2 (40/60 and 70/30 vol.%) and CO2/CH4 (50/50 vol.%) binary gas mixtures in a purpose-built fixed-bed set-up. The performance of the resin-derived carbons to separate CO2 was superior to that of reference commercial carbons in terms of CO2 uptake, breakthrough time and column efficiency. These adsorbents presented high CO2/H2 and CO2/CH4 selectivity values, were easily completely regenerated and did not show capacity decay after multiple cycling. Breakthrough capacities reached 2.11 and 2.03 mmol g−1 at 25 °C for 70/30 CO2/H2 and 50/50 CO2/CH4, respectively. The No2OS-1000 adsorbent, produced from phenol–formaldehyde resin and olive stones (20:80 wt.), gave the greatest values of CO2 capture capacity on a volumetric basis and CO2/CH4 selectivity, which may be advantageous to biogas purification applications because it reduces the size of the necessary equipment.This work was carried out with financial support from the Spanish MINECO (Project ENE2011-23467), co-financed by the European Regional Development Fund (ERDF). N.A.-G. acknowledges a FPI Predoctoral fellowship from the Spanish MINECO, co-financed by the European Social Fund.Peer reviewe

CFD modeling of oxy-coal combustion: Prediction of burnout, volatile and NO precursors release

The devolatilisation step of coal is a vital stage in both air–coal and oxy-coal combustion and there is interest in whether methods of estimating the reaction parameters are similar for both cases. A network pyrolysis model, the FG-DVC (Functional Group-Depolymerisation Vaporisation Cross-linking) code was employed to evaluate the effect of temperature (1273–1773 K) and heating rate (104–106 K/s) on the devolatilisation parameters of two coals of different rank. The products distribution between char and volatiles, and volatiles and NH3/HCN release kinetics were also determined. In order to assess the accuracy of the FG-DVC predictions, the values for nitrogen distribution and devolatilisation kinetics obtained for a temperature of 1273 K and a heating rate of 105 K/s were included as inputs in a Computational Fluid Dynamics (CFD) model for oxy-coal combustion in an entrained flow reactor (EFR). CFD simulations with the programme default devolatilisation kinetics were performed. The oxygen content in oxy-firing conditions ranged between 21% and 35%, and air-firing conditions were also employed as a reference. The experimental coals burnouts and oxygen concentrations from the EFR experiments were employed to test the accuracy of the CFD model. The temperature profiles, burning rates, char burnout and NO emissions during coal combustion in both air and O2/CO2 atmospheres were predicted. The predictions obtained when using the CFD model with FG-DVC coal devolatilisation kinetics were much closer to the experimental values than the predictions obtained with the ANSYS Fluent (version 12) program default kinetics. The predicted NO emissions under oxy-firing conditions were in good agreement with the experimental values.The present study was carried out with financial support from the Spanish MICINN (Project PS-120000-2005-2) co-financed by the European Regional Development Fund. L.A. and J.R. acknowledge funding from the CSIC JAE program, which was cofinanced by the European Social Fund, and the Asturias Regional Government (PCTI program), respectively. MG acknowledges financial support from E.ON UK, and for an EPSRC Dorothy Hodgkin Postgraduate Award. We also thank Dr L Ma for helpful discussions.Peer reviewe