Poincar\'e's polyhedron theorem for cocompact groups in dimension 4

We prove a version of Poincar\'e's polyhedron theorem whose requirements are as local as possible. New techniques such as the use of discrete groupoids of isometries are introduced. The theorem may have a wide range of applications and can be generalized to the case of higher dimension and other geometric structures. It is planned as a first step in a program of constructing compact $\mathbb C$-surfaces of general type satisfying $c_1^2=3c_2$.Comment: 15 pages, 1 figure, 9 references. Introduction revised. Example 3.16 adde

ASPECTOS SUBJETIVOS DO CONSUMO E IMPLICAÇÕES NO IMPACTO AMBIENTAL

Qualquer objeto possui funções e apelos que ultrapassam e se somam à sua função nominal, significados subjetivos, que enriquecem sua relação com o usuário. Entretanto, os significados subjetivos também são manipulados pelo setor produtivo com o objetivo de estimular o descarte prematuro e nova venda, a obsolescência programada. As estratégias de ecodesign em geral são viáveis tecnicamente, mas enfrentam o desafio da falta de interesse por parte do setor produtivo e a resistência cultural à sua implantação. A dificuldade de introdução dessas propostas ocorre pela cultura do desperdício e manipulação dos aspectos subjetivos, que desenvolveram uma sociedade com forte desejo de posse, fascínio pelo novo e a valorização da virgindade dos produtos

O USO DE ESTRATÉGIAS DE ECODESIGN POR PROJETISTAS BRASILEIROS

Este artigo tece considerações sobre a percepção que designers brasileiros têm do Ecodesign, da busca de informações ambientais e as dificuldades que encontram para aplicar as estratégias de Ecodesign em seus projetos. As informações foram levantadas a partir de uma pesquisa realizada junto a alguns projetistas de diversos estados do país

Root canal disinfection and maintenance of the remnant tooth tissues by using grape seed and cranberry extracts

The purpose of this study was to perform an integrative review on the effects of cranberry and grape seed extracts concerning the disinfection of root canals maintaining the strength of the remnant tooth tissues' structure. A bibliographical search was carried out on the PubMed electronic platform using the following key terms: cranberry, grape seed, vaccinium macrocarpon, proanthocyanidin, antibacterial, antimicrobial, decontamination, disinfection, bacteria removal, bacteria eradication, bacteria elimination, endodontic, root canal, faecalis, and strength. The inclusion criteria involved articles published in the English language, until March, 2022, reporting the antibacterial effect of grape seed and cranberry extracts. Of 185 studies identified, 13 studies were selected for the present review. The grape seed extract (GSE), composed of proanthocyanidins, showed an antioxidant activity against the main bacteria found in endodontic secondary infection. The percentage of bacteria removal was recorded at around 96.97% by using GSE. Studies on cranberry extracts, which are composed of proanthocyanidins, revealed antimicrobial effects against bacteria related to periodontitis and dental caries. Additionally, GSE or cranberry allowed the dentin collagen cross-linking that preserved the 3D collagen network leading to the maintenance of the strength of the remnant tooth structure. However, the contaminated smear layer could not be removed by using only GSE or cranberry. Cranberry extracts and GSE revealed a significant antimicrobial activity in endodontic disinfection without changing the mechanical properties of the remnant dentin tissues. Furthermore, those components can be associated with traditional compounds to enhance their antimicrobial effects and eliminate the smear layer

Low-resolution structural studies of human Stanniocalcin-1

Background: Stanniocalcins (STCs) represent small glycoprotein hormones, found in all vertebrates, which have been functionally implicated in Calcium homeostasis. However, recent data from mammalian systems indicated that they may be also involved in embryogenesis, tumorigenesis and in the context of the latter especially in angiogenesis. Human STCI is a 247 amino acids protein with a predicted molecular mass of 27 kDa, but preliminary data suggested its di- or multimerization. The latter in conjunction with alternative splicing and/or post-translational modification gives rise to forms described as STC(50) and "big STC", which molecular weights range from 56 to 135 kDa. Results: In this study we performed a biochemical and structural analysis of STCI with the aim of obtaining low resolution structural information about the human STCI, since structural information in this protein family is scarce. We expressed STCI in both E. coli and insect cells using the baculo virus system with a C-terminal 6 x His fusion tag. From the latter we obtained reasonable amounts of soluble protein. Circular dichroism analysis showed STCI as a well structured protein with 52% of alpha-helical content. Mass spectroscopy analysis of the recombinant protein allowed to assign the five intramolecular disulfide bridges as well as the dimerization Cys202, thereby confirming the conservation of the disulfide pattern previously described for fish STCI. SAXS data also clearly demonstrated that STCI adopts a dimeric, slightly elongated structure in solution. Conclusion: Our data reveal the first low resolution, structural information for human STCI. Theoretical predictions and circular dichroism spectroscopy both suggested that STCI has a high content of alpha-helices and SAXS experiments revealed that STCI is a dimer of slightly elongated shape in solution. The dimerization was confirmed by mass spectrometry as was the highly conserved disulfide pattern, which is identical to that found in fish STCI

Laser-texturing and traditional surface modification to improve the adhesion of glass fiber-reinforced composite posts to resin cements

Objectives The aim of this study was to perform experimental evaluation of the synergistic effects of laser-texturing and different traditional surface modification approaches to improve the push-out bond strength of glass fiber-reinforced composite (GFRC) posts to resin-matrix cements used in endodontically treated teeth rehabilitation. Methods One hundred and ten freshly extracted mandibular single-rooted premolars were endodontically treated and groups of specimens were divided according to the GFRC cementation after different surface treatment, as follow (n = 10): silane-based conditioning (SIL); 9.7 % HF acid-etching (HF); 35 % H2O2 etching (H2O2); grit-blasting (GB); HF plus H2O2 etching (HFH2O2); 6 W Nd:YAG laser-texturing (L6W); 4.5 W Nd:YAG laser-texturing (L4.5W); 3 W Nd:YAG laser-texturing (L3W); 3 W Nd:YAG plus 35 % H2O2 (L3WH2O2); 3 W Nd:YAG plus SIL (L3WSIL); and no-treatment (C). GFRC posts were cemented into the tooth root canals using a dual-cured resin cement. Then, specimens were cross-sectioned and mechanically assessed by push-out bond strength tests. Specimens were inspected by optical microscopy and scanning electron microscopy at magnification from × 30 up to × 2000. Data were analyzed using one-way analysis of variance and Tukey post hoc test (p = 0.05). Results Surface analyses of the GFRC posts showed a rough and retentive morphological aspect with a removal of the outer epoxy matrix layer and exposure of glass fibers after laser-texturing, grit-blasting or etching under 35 % H2O2. The highest bond strength values at 21.8 MPa was recorded for GFRC posts after laser-texturing on 3W plus silane-based conditioning followed by the group etched with 35 % H2O2 (20.5 MPa). The failure mode was characterized as cohesive and mixed pathways. The lowest bond strength values around 5 and 9 MPa were recorded for untreated GFRC surfaces or specimens etched with HF that was noticeable by adhesive failure pathways. Conclusions The combination of acidic etching and silane conditioning with laser-texturing at medium intensity promoted an adequate surface modification of GFRC posts and increased adhesion to a resin-matrix cement. Such combination of physicochemical approaches can enhance the long-term mechanical behavior of the restorative interface at endodontically treated teeth. Clinical relevance Combining traditional and novel physicochemical approaches can provide promising adhesion pathways for glass fiber-reinforced composite posts to resin-matrix cements. A high mechanical interlocking of the resin-matrix cements and stable retention of the teeth root intracanal posts can decrease the risks of clinical failures by fracture and detachment of the adhesive interface.info:eu-repo/semantics/acceptedVersio

Flexural response of HSC girders strengthened with non- and prestressed CFRP laminates

An experimental programme was carried out to characterise the flexural response of prestressed highstrength concrete (HSC) girders strengthened with CFRP laminates. For that purpose, four beams with 20 m span were subjected to four-point bending loads and the effectiveness of two distinct strengthening strategies was analysed. The following testing situations have been considered: one girder was externally strengthened with CFRP laminates, whereas one was externally strengthened with prestressed CFRP laminates; the two remaining girders were left unstrengthened and were used as control. The monitoring system included the measurement of deflections at critical sections, strains in pre-selected points of the concrete girder and CFRP laminates and the applied loading, respectively using displacement transducers, strain gages and load cells. Herein, the tests are thoroughly described and the most relevant results and conclusions are presented