Reabilitação Oral: prótese livre de metal, Removível e implantes. Um caso de 12 anos de acompanhamento

The literature has suggested that the association of removable partial dentures with dental implants can improve the quality of life of patients. Thus, the purpose of this study was to present a case report. This case report describes the development of a removable partial denture associated with dental implants bilaterally been monitored for 12 years, and the efficacy of the proposed treatment. The radiographic controls demonstrated no changes on bone tissue. The maxillary arch was rehabilitated with metal-free crowns. The patient was fully satisfied with this technique providing stability, esthetics, and proper function. It was concluded that the technique of using removable partial dentures associated with dental implants is viable and show the advantages of improved function, aesthetics and cost reductions in rehabilitation treatment.

Design and characterization of α-melanotropin peptide analogs cyclized through rhenium and technetium metal coordination

α-Melanocyte stimulating hormone (α-MSH) analogs, cyclized through site-specific rhenium (Re) and technetium (Tc) metal coordination, were structurally characterized and analyzed for their abilities to bind α-MSH receptors present on melanoma cells and in tumor-bearing mice. Results from receptor-binding assays conducted with B16 F1 murine melanoma cells indicated that receptor-binding affinity was reduced to approximately 1% of its original levels after Re incorporation into the cyclic Cys4,10, d-Phe7–α-MSH4-13 analog. Structural analysis of the Re–peptide complex showed that the disulfide bond of the original peptide was replaced by thiolate–metal–thiolate cyclization. A comparison of the metal-bound and metal-free structures indicated that metal complexation dramatically altered the structure of the receptor-binding core sequence. Redesign of the metal binding site resulted in a second-generation Re–peptide complex (ReCCMSH) that displayed a receptor-binding affinity of 2.9 nM, 25-fold higher than the initial Re–α-MSH analog. Characterization of the second-generation Re–peptide complex indicated that the peptide was still cyclized through Re coordination, but the structure of the receptor-binding sequence was no longer constrained. The corresponding 99mTc- and 188ReCCMSH complexes were synthesized and shown to be stable in phosphate-buffered saline and to challenges from diethylenetriaminepentaacetic acid (DTPA) and free cysteine. In vivo, the 99mTcCCMSH complex exhibited significant tumor uptake and retention and was effective in imaging melanoma in a murine-tumor model system. Cyclization of α-MSH analogs via 99mTc and 188Re yields chemically stable and biologically active molecules with potential melanoma-imaging and therapeutic properties.

Chemically modified ribbon edge stimulated H2 dissociation: A first-principles computational study

First-principles computational studies indicate that (B, N, or O)-doped graphene ribbon edges can substantially reduce the energy barrier for H2 dissociative adsorption. The low barrier is competitive with many widely used metal or metal oxide catalysts. This suggests that suitably functionalized graphene architectures are promising metal-free alternatives for low-cost catalytic processes.

Taguchi optimized synthesis of graphene films by copper catalyzed ethanol decomposition

Taguchi method is for the first time applied to optimize the synthesis of graphene films by copper-catalyzed decomposition of ethanol. In order to find the most appropriate experimental conditions for the realization of thin high-grade films, six experiments suitably designed and performed. The influence of temperature (1000–1070 °C) and synthesis duration (1–30 min) and hydrogen flow (0–100 sccm) on the number of graphene layers and defect density in the graphitic lattice was ranked by monitoring the intensity of the 2D- and D-bands relative to the G-band in the Raman spectra. After critical examination and adjusting of the conditions predicted to give optimal results, a continuous film consisting of 2–4 nearly defect-free graphene layers was obtained.

Design of redox/radical sensing molecules via Nitrile Imine-Mediated Tetrazole-ene Cycloaddition (NITEC)

The current study introduces a novel synthetic avenue for the preparation of profluorescent nitroxides via nitrile imine-mediated tetrazole-ene cycloaddition (NITEC). The photoinduced cycloaddition was performed under metal-free, mild conditions allowing the preparation of a library of the nitroxide functionalized pyrazolines and corresponding methoxyamines. High reaction rates and full conversion were observed, with the presence of the nitroxide having no significant impact on the cycloaddition performance. The formed products were investigated with respect to their photophysical properties in order to quantify their “switch on/off” behavior. The fluorescence quenching performance is strongly dependent on the distance between the chromophore and the free radical spin as demonstrated theoretically and experimentally. Highest levels of fluorescence quenching were achieved for pyrazolines with the nitroxide directly fused to the chromophore. Importantly, the pyrazoline profluorescent nitroxides were shown to efficiently act as sensors for redox/radical processes.

Carbon nanodot decorated graphitic carbon nitride: New insights into the enhanced photocatalytic water splitting from ab initio studies

Interfacing carbon nanodots (C-dots) with graphitic carbon nitride (g-C3N4) produces a metal-free system that has recently demonstrated significant enhancement of photo-catalytic performance for water splitting into hydrogen [Science, 2015, 347, 970–974]. However, the underlying photo-catalytic mechanism is not fully established. Herein, we have carried out density functional theory (DFT) calculations to study the interactions between g-C3N4 and trigonal/hexagonal shaped C-dots. We find that hybrid C-dots/g-C3N4 can form a type-II van der Waals heterojunction, leading to significant reduction of band gap. The C-dot decorated g-C3N4 enhances the separation of photogenerated electron and hole pairs and the composite's visible light response. Interestingly, the band alignment of C-dots and g-C3N4 calculated by the hybrid functional method indicates that C-dots act as a spectral sensitizer in hybrid C-dots/g-C3N4 for water splitting. Our results offer new theoretical insights into this metal-free photocatalyst for water splitting.

Closo versus Hypercloso Metallaboranes: A DFT Study

The structures and electronic relationship of 9-, 10-, 11-, and 12-vertex closo and hypercloso (isocloso) etallaboranes are explored using OFT calculations. The role of the transition metal in stabilizing the hypercloso borane structures is explained using the concept of orbital compatibility. The hypercloso structures, C6H6MBn-1Hn-1 (n = 9-12; M = Fe, Ru, and Os) are taken as model complexes. Calculations on metal free polyhedral borane BnHn suggest that n vertex hypercloso structures need only n skeleton electron pairs (SEPs), but the structure will have one or more six-degree vertices, whereas the corresponding closo structures with n + 1 SEPs have only four- and five-degree vertices. This high-degree vertex of hypercloso structures can be effectively occupied by transition metal fragments with their highly diffused orbitals. Calculations further show that a heavy transition metal with more diffused orbitals prefers over a light transition metal to form hypercloso geometry, This is in accordance with the fact that there are more experimentally characterized hypercloso structures with the heavy transition metals. The size of the exohedral ligands attached to the metal atom also plays a role in deciding the stability of the hypercloso structure. The interaction between the borane and the metal fragments in the hypercloso geometry is analyzed using the fragment molecular orbital approach. The interconversion of the closo and hypercloso structures by the addition and removal of the electrons is also discussed in terms of the correlation diagrams.

Probing the mechanism of benzaldehyde reduction to chiral hydrobenzoin on the CNT surface under near-UV light irradiation

Metal-free CNTs exhibit high activity (conversion rate 99.6%, 6 h) towards the synthesis of chiral hydrobenzoin from benzaldehyde under near-UV light irradiation (320–400 nm). The CNT structure before and after the reaction, the interaction between the molecule and the CNT surface, the intermediate products, the substitution effect and the influence of light on the reaction were examined using various techniques. A photo-excited conduction electron transfer (PECET) mechanism for the photocatalytic reduction using CNTs has been proposed. This finding provides a green photocatalytic route for the production of hydrobenzoin and highlights a potential photocatalytic application of CNTs.

Elevated CDCP1 predicts poor patient outcome and mediates ovarian clear cell carcinoma by promoting tumor spheroid formation, cell migration and chemoresistance

Hematogenous metastases are rarely present at diagnosis of ovarian clear cell carcinoma (OCC). Instead dissemination of these tumors is characteristically via direct extension of the primary tumor into nearby organs and the spread of exfoliated tumor cells throughout the peritoneum, initially via the peritoneal fluid, and later via ascites that accumulates as a result of disruption of the lymphatic system. The molecular mechanisms orchestrating these processes are uncertain. In particular, the signaling pathways used by malignant cells to survive the stresses of anchorage-free growth in peritoneal fluid and ascites, and to colonize remote sites, are poorly defined. We demonstrate that the transmembrane glycoprotein CUB-domain-containing protein 1 (CDCP1) has important and inhibitable roles in these processes. In vitro assays indicate that CDCP1 mediates formation and survival of OCC spheroids, as well as cell migration and chemoresistance. Disruption of CDCP1 via silencing and antibody-mediated inhibition markedly reduce the ability of TOV21G OCC cells to form intraperitoneal tumors and induce accumulation of ascites in mice. Mechanistically our data suggest that CDCP1 effects are mediated via a novel mechanism of protein kinase B (Akt) activation. Immunohistochemical analysis also suggested that CDCP1 is functionally important in OCC, with its expression elevated in 90% of 198 OCC tumors and increased CDCP1 expression correlating with poor patient disease-free and overall survival. This analysis also showed that CDCP1 is largely restricted to the surface of malignant cells where it is accessible to therapeutic antibodies. Importantly, antibody-mediated blockade of CDCP1 in vivo significantly increased the anti-tumor efficacy of carboplatin, the chemotherapy most commonly used to treat OCC. In summary, our data indicate that CDCP1 is important in the progression of OCC and that targeting pathways mediated by this protein may be useful for the management of OCC, potentially in combination with chemotherapies and agents targeting the Akt pathway.

Crystal Structure of Staphylococcus aureus Metallopeptidase (Sapep) Reveals Large Domain Motions between the Manganese-bound and Apo-states

Proteases belonging to the M20 family are characterized by diverse substrate specificity and participate in several metabolic pathways. The Staphylococcus aureus metallopeptidase, Sapep, is a member of the aminoacylase-I/M20 protein family. This protein is a Mn2+-dependent dipeptidase. The crystal structure of this protein in the Mn2+-bound form and in the open, metal-free state suggests that large interdomain movements could potentially regulate the activity of this enzyme. We note that the extended inactive conformation is stabilized by a disulfide bond in the vicinity of the active site. Although these cysteines, Cys(155) and Cys(178), are not active site residues, the reduced form of this enzyme is substantially more active as a dipeptidase. These findings acquire further relevance given a recent observation that this enzyme is only active in methicillin-resistant S. aureus. The structural and biochemical features of this enzyme provide a template for the design of novel methicillin-resistant S. aureus-specific therapeutics.

A Versatile C-H Functionalization of Tetrahydroisoquinolines Catalyzed by Iodine at Aerobic Conditions

A versatile aerobic catalytic system (I-2 and O-2/TBHP) for C-H functionalization is reported. This CDC (cross-dehydrogentive coupling) reaction is compatible with a large number of nucleophiles and is performed under ambient reaction conditions. The scope of the metal-free CDC is illustrated by synthesizing a variety of functionalized tetrahydroisoquinolines and N,N-dimethylaniline. The highlight of the method is a Friedel-Crafts reaction of phenols and indole with tertiary amines.

Facile hydrothermal synthesis of carbon nanoparticles and possible application as white light phosphors and catalysts for the reduction of nitrophenol

We report a simple hydrothermal synthesis of highly reproducible carbon nanoparticles in a size range between 2 and 7 nmfroma single precursor sucrose without either surface passivating agents or acids and bases. The carbon nanoparticles can be used as white light phosphors, especially for ultraviolet light emitting diodes and metal-free catalyst for the reduction of nitrophenol.

A 3.8-V earth-abundant sodium battery electrode

Rechargeable lithium batteries have ushered the wireless revolution over last two decades and are now matured to enable green automobiles. However, the growing concern on scarcity and large-scale applications of lithium resources have steered effort to realize sustainable sodium-ion batteries, Na and Fe being abundant and low-cost charge carrier and redox centre, respectively. However, their performance is limited owing to low operating voltage and sluggish kinetics. Here we report a hitherto-unknown material with entirely new composition and structure with the first alluaudite-type sulphate framework, Na2Fe2(SO4)(3), registering the highest-ever Fe3+/ Fe2+ redox potential at 3.8V (versus Na, and hence 4.1V versus Li) along with fast rate kinetics. Rare-metal-free Na-ion rechargeable battery system compatible with the present Li-ion battery is now in realistic scope without sacrificing high energy density and high power, and paves way for discovery of new earth-abundant sustainable cathodes for large-scale batteries.

Regioselective Thiolation of Arenes and Heteroarenes: C-H Functionalization Strategy for C-S Bond Formation

A facile transition-metal-free oxidative cross-dehydrogenative coupling reaction involving selective formation of a C-S bond leading to the synthesis of arylthiobenzoxazoles, heteroarylthiobenzoxazoles, and arylthiobenzothiazoles has been described. This highly regioselective C-H functionalization reaction with electron-rich aromatic systems including heteroaromatics is achieved by reversing the reactivity of sulfur in the presence of a suitable oxidant and strong acid.

Regioselective Synthesis of Vinyl Halides, Vinyl Sulfones, and Alkynes: A Tandem Intermolecular Nucleophilic and Electrophilic Vinylation of Tosylhydrazones

A diazo species is trapped in an intermolecular fashion by two independent ion species in tandem at the carbene center to install an electrophile and a nucleophile on the same carbon. This metal-free concept, which is unprecedented, has been illustrated by regioselective synthesis of a variety of vinyl halides, vinyl sulfones, and alkyne derivatives.