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)

Preparation of carbon dioxide adsorbents from the chemical activation of urea–formaldehyde and melamine–formaldehyde resins

10 pages, 4 figures, 3 tables.-- Available online Aug 14, 2006.Adsorption is considered to be one of the more promising technologies for the capture of CO2 from flue gases. In general, nitrogen enrichment is reported to be effective in enhancing the specific adsorbent–adsorbate interaction for CO2. Nitrogen enriched carbons were produced from urea–formaldehyde and melamine–formaldehyde resins polymerised in the presence of K2CO3 as a chemical activation agent, with activation undertaken over a range of temperatures. CO2 adsorption capacity was determined to be dependent upon both textural properties and more importantly nitrogen functionality. Adsorbents capable of capturing above 8 wt.% CO2 at 25°C were produced from the chemical activation of urea–formaldehyde resin at 500°C. Chemical activation seems to produce more effective adsorbents than CO2 activation.The authors are grateful for support for this work provided by the Research Fund for Coal and Steel (RFC-CR-03008) and for CP a grant from Plan I + D + I Gobierno del Principado de Asturias.Peer reviewe

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

Experimental and Simulation Study of Adsorption in Postcombustion Conditions Using a Microporous Biochar. 1. CO2 and N2 Adsorption

The influence of N2 on CO2 adsorption was evaluated using a microporous biochar with a narrow pore size distribution. The adsorption isotherms of pure CO2 and N2 were measured at 0, 30, 50, and 70 °C up to 120 kPa and fitted to the Toth adsorption model. Dynamic breakthrough experiments were carried out in a fixed-bed adsorption unit using binary mixtures with compositions representative of different postcombustion streams (8–30% CO2) from ambient temperature to 70 °C. Dynamic adsorption experiments were simulated to validate the mathematical model of the adsorption process, as a necessary step for its later use for process design. The Ideal Adsorption Solution (IAS) theory, based on the pure component adsorption models, was used to account for competitive adsorption with satisfactory results. The information gathered in the present work will be used to extend the validity of the model to the adsorption of postcombustion streams containing H2O in part 2.Work was carried out with financial support from the HiPerCap Project of the European Union 7th Framework Programme FP7 (2007-2013; Grant Agreement number: 60855). M.G.P. acknowledges funding from the CSIC (JAE-Doc program cofinanced by the European Social Fund). N.Q. acknowledges funding from the Government of the Principado de Asturias (Severo Ochoa Program). The authors also appreciate the support from the technical consultants of AspenTechnology Inc., M.M. and E.L.Peer reviewe

Adjunctive liraglutide treatment in patients with persistent or recurrent type 2 diabetes after metabolic surgery (GRAVITAS): a randomised, double-blind, placebo-controlled trial

Background Many patients with type 2 diabetes do not achieve sustained diabetes remission after metabolic (bariatric) surgery for the treatment of obesity. Liraglutide, a glucagon-like peptide-1 analogue, improves glycaemic control and reduces bodyweight in patients with type 2 diabetes. Our aim was to assess the safety and efficacy of liraglutide 1·8 mg in patients with persistent or recurrent type 2 diabetes after metabolic surgery. Methods In the GRAVITAS randomised double-blind, placebo-controlled trial, we enrolled adults who had undergone Roux-en-Y gastric bypass or vertical sleeve gastrectomy and had persistent or recurrent type 2 diabetes with HbA1c levels higher than 48 mmol/mol (6·5%) at least 1 year after surgery from five hospitals in London, UK. Participants were randomly assigned (2:1) via a computer-generated sequence to either subcutaneous liraglutide 1·8 mg once daily or placebo, both given together with a reduced-calorie diet, aiming for a 500 kcal per day deficit from baseline energy intake, and increased physical activity. The primary outcome was the change in HbA1c from baseline to the end of the study period at 26 weeks, assessed in patients who completed the trial. Safety was assessed in the safety analysis population, consisting of all participants who received either liraglutide or placebo. This trial is registered with EudraCT, number 2014-003923-23, and the ISRCTN registry, number ISRCTN13643081. Findings Between Jan 29, 2016, and May 2, 2018, we assigned 80 patients to receive either liraglutide (n=53) or placebo (n=27). 71 (89%) participants completed the study and were included in the principal complete-cases analysis. In a multivariable linear regression analysis, with baseline HbA1c levels and surgery type as covariates, liraglutide treatment was associated with a difference of −13·3 mmol/mol (−1·22%, 95% CI −19·7 to −7·0; p=0·0001) in HbA1c change from baseline to 26 weeks, compared with placebo. Type of surgery had no significant effect on the outcome. 24 (45%) of 53 patients assigned to liraglutide and 11 (41%) of 27 assigned to placebo reported adverse effects: these were mainly gastrointestinal and in line with previous experience with liraglutide. There was one death during the study in a patient assigned to the placebo group, which was considered unrelated to study treatment. Interpretation These findings support the use of adjunctive liraglutide treatment in patients with persistent or recurrent type 2 diabetes after metabolic surgery

Design of a precision compactor for use in guided bone regeneration in the area of oral surgery

During the processes of guided bone regeneration in the maxillary bones, which aim to recover or preserve support tissue for the placement of implants on which dental prostheses are retained, the use of various particulate graft biomaterials from different sources (animal or synthetic) is standardized. At present, the pressure of compaction of this material in the recipient bone is manual, dependent on the clinician, although there is some scientific evidence on the effects of different compressive forces on angiogenesis and prognosis of the regeneration of the grafted areas. The aim of the present study is to design, calibrate and verify in vitro a compaction instrument for clinical use, which allows a controlled and precise compaction pressure of the particulate graft biomaterial and standardize the procedure. The designed instrument is a precision compactor of adequate size for proper intra and extraoral clinical manageability and manufactured in a sterilizable material by autoclaving. The range of compression that allows (0 -1, 82 Newton), is within the forces that are commonly applied in surgery and that have been determined by a specific test on 8 oral surgeons. Instrument calibration has been performed by an independent accredited company. The testing of the instrument was carried out by an in vitro test where the biomaterial was compacted at different forces (0, 80 and 1, 82 Newton) and was observed by a computerized micro-tomography that when increasing the compression force, decreased the space between particles provided for the migration and proliferation of new blood vessels and cells. Durante los procedimientos de regeneración ósea guiada en los huesos maxilares, que tienen como objetivo recuperar o preservar tejido de soporte para la colocación de implantes sobre los que se retienen las prótesis dentales, está estandarizado el uso de diversos biomateriales de injerto particulado de diferente procedencia (animal o sintético). En la actualidad la presión de compactación de dicho material en el hueso receptor es manual, clínico dependiente, pese a que existe cierta evidencia científica sobre los efectos de las diferentes fuerzas de compresión en la angiogénesis y pronóstico de la regeneración de las zonas injertadas. El objetivo del presente estudio es el de diseñar, calibrar y comprobar in vitro un instrumento de compactación para uso clínico, que permita una presión de compactación controlada y precisa del biomaterial de injerto particulado y estandarizar el procedimiento. El instrumento diseñado es un compactador de precisión de tamaño adecuado para una correcta manejabilidad clínica intra y extraoral y fabricado en un material esterilizable por autoclavado. El rango de compresión que permite (0 – 1, 82 Newton), está dentro de las fuerzas que se aplican comúnmente en cirugía y que se han determinado mediante una prueba específica sobre 8 cirujanos orales. La calibración del instrumento se ha realizado por una empresa acreditada independiente. La comprobación del instrumento se ha realizado mediante un ensayo in vitro donde se compactó el biomaterial a diferentes fuerzas (0, 80 y 1, 82 Newton) y se observó mediante micro-tomografía computerizada que al aumentar la fuerza de compresión disminuía el espacio entre partículas provisto para la migración y proliferación de los nuevos vasos sanguíneos y células

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

The Aguablanca Ni–(Cu) sulfide deposit, SW Spain: geologic and geochemical controls and the relationship with a midcrustal layered mafic complex

The Aguablanca Ni–(Cu) sulfide deposit is hosted by a breccia pipe within a gabbro–diorite pluton. The deposit probably formed due to the disruption of a partially crystallized layered mafic complex at about 12– 19 km depth and the subsequent emplacement of melts and breccias at shallow levels (<2 km). The ore-hosting breccias are interpreted as fragments of an ultramafic cumulate, which were transported to the near surface along with a molten sulfide melt. Phlogopite Ar–Ar ages are 341– 332 Ma in the breccia pipe, and 338–334 Ma in the layered mafic complex, and are similar to recently reported U–Pb ages of the host Aguablanca Stock and other nearby calcalkaline metaluminous intrusions (ca. 350–330 Ma). Ore deposition resulted from the combination of two critical factors, the emplacement of a layered mafic complex deep in the continental crust and the development of small dilational structures along transcrustal strike-slip faults that triggered the forceful intrusion of magmas to shallow levels. The emplacement of basaltic magmas in the lower middle crust was accompanied by major interaction with the host rocks, immiscibility of a sulfide melt, and the formation of a magma chamber with ultramafic cumulates and sulfide melt at the bottom and a vertically zoned mafic to intermediate magmas above. Dismembered bodies of mafic/ultramafic rocks thought to be parts of the complex crop out about 50 km southwest of the deposit in a tectonically uplifted block (Cortegana Igneous Complex, Aracena Massif). Reactivation of Variscan structures that merged at the depth of the mafic complex led to sequential extraction of melts, cumulates, and sulfide magma. Lithogeochemistry and Sr and Nd isotope data of the Aguablanca Stock reflect the mixing from two distinct reservoirs, i.e., an evolved siliciclastic middle-upper continental crust and a primitive tholeiitic melt. Crustal contamination in the deep magma chamber was so intense that orthopyroxene replaced olivine as the main mineral phase controlling the early fractional crystallization of the melt. Geochemical evidence includes enrichment in SiO2 and incompatible elements, and Sr and Nd isotope compositions (87Sr/86Sri 0.708–0.710; 143Nd/144Ndi 0.512–0.513). However, rocks of the Cortegana Igneous Complex have low initial 87Sr/86Sr and high initial 143Nd/144Nd values suggesting contamination by lower crustal rocks. Comparison of the geochemical and geological features of igneous rocks in the Aguablanca deposit and the Cortegana Igneous Complex indicates that, although probably part of the same magmatic system, they are rather different and the rocks of the Cortegana Igneous Complex were not the direct source of the Aguablanca deposit. Crust–magma interaction was a complex process, and the generation of orebodies was controlled by local but highly variable factors. The model for the formation of the Aguablanca deposit presented in this study implies that dense sulfide melts can effectively travel long distances through the continental crust and that dilational zones within compressional belts can effectively focus such melt transport into shallow environments