Challenges for integrated design (ID) in sustainable buildings

It is often argued that integrated design (ID) is a powerful way to enhance collaboration in construction projects. This collaboration is seen as a way of improving innovation to create more sustainable buildings. Contrary to the traditional silo-type and linear design process, ID is based on upfront stakeholder involvement and a holistic approach to project decision-making. Although ID’s premises are theoretically-founded, a close empirical look at its practices shows that numerous challenges compromise its results and efficiency. This study examines the ID process through an iterative process that includes the construction of a conceptual framework and its empirical validation. We examine three green construction projects in Canada. Based on the analysis of 26 interviews with key project stakeholders and more than 198 construction documents, the study assembles – and ultimately applies – a multi-lens framework based on four themes: the fragmented nature of construction; risk perception; stakeholders’ commitment; and efficiency in the design process. Results show that three tensions arise in ID practices: between collaboration and process efficiency, between short-term and long-term goals, and between integrated methods and traditional ones. The study sheds light on ID limits and reveals how stakeholders can improve their interactions to design more sustainable buildings.     

Qualitative analysis of files of four different rotary systems,before and after being used for the twelfth time

The aim of this study was to make a comparative evaluation of the surface topography of the cervical third and tip of four different rotary systems, before and after being used 12 times, in resin blocks with simulated root canals with standardized 45° curvatures, and analyzed by scanning electronic microscopy (SEM). A total of 1,440 resin blocks with simulated root canals and standardized curvatures were used. The blocks were divided into four groups and prepared by the crown down technique according to the manufacturers' recommendations: Group 1 (G1)—K3®, Group 2 (G2)—Protaper Universal®, Group 3 (G3)—Twisted Files®, and Group 4 (G4)—Biorace®. After each preparation, the instruments were washed and autoclaved. A total of 24 instruments were selected, being three new instruments and three after having been used for the 12th time, from each group. These instruments were analyzed by SEM. To perform the evaluation, 24 micrographs were observed by 12 evaluators who attributed a score to the images according to a template. In the qualitative analysis of the cervical region and tip of new instruments, it was observe that the files of Groups G4 and G2 were the least rough and those of G1, the roughest. In the same manner, the cervical region of the instruments was qualitatively analyzed after the 12th time of using them, and there was no statistically significant difference at a level of 1% (ANOVA P < 0.01) between G2 and G4 as well as between G1 and G3. As regards the tip, it was observed that there was no statistically significant difference, at a level of 1%, between the groups: G1 and G3, G1 and G4, and between G3 and G4, and there was statistically significant difference at a level of 1%, between group G2 and the other groups, with G3 having the greatest roughness (ANOVA P < 0.01). Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.     

Exodontia‐induced muscular hypofunction by itself or associated to chronic stress impairs masseter muscle morphology and its mitochondrial function

Stress is associated with orofacial pain sensitivity and is qualified as a temporomandibular disorder risk factor. During stressful periods, painful thresholds of masticatory muscles in individuals suffering muscle facial pain are significantly lower than in controls, but the exact physiologic mechanism underlying this relation remains unclear. Our hypothesis is that chronic unpredictable stress and masticatory hypofunction induce morphologic and metabolic masseter muscle changes in rats. For test this hypothesis, adult Wistar rats were submitted to chronic unpredictable stress and/or exodontia of left molars and the left masseter muscle was removed for analysis. The parameters evaluated included ultrastructure, oxidative level, metabolism activity and morphological analysis in this muscle. Our data show by histological analysis, that stress and exodontia promoted a variation on diameters and also angled contours in masseter fibers. The masticatory hypofunction increased oxidative metabolism as well as decreased reactive species of oxygen in masseter muscle. The ultrastructural analysis of muscle fibers showed disruption of the sarcoplasmic reticulum cisterns in certain regions of the fiber in stress group, and the disappearance of the sarcoplasmic reticulum membrane in group with association of stress and exodontia. Our findings clarify mechanisms by which chronic stress and masticatory hypofunction might be involved in the pathophysiology of muscular dysfunctions. Masticatory hypofunction influenced oxidative stress and induced oxidative metabolism on masseter muscle, as well as altered its fiber morphology. Chronic stress presented malefic effect on masseter morphology at micro and ultra structurally. When both stimuli were applied, there were atrophic fibers and a complete mitochondrial derangement.     

Connective Tissue Reaction of Rats to a New Zinc‐Oxide‐Eugenol Endodontic Sealer

The aim of this study was to evaluate the biocompatibility in rat subcutaneous connective tissue of a new zinc oxide endodontic sealer (Endomethasone N) compared to those provided by Endofill and Sealer 26. Polyethylene tubes containing the test materials were implanted into dorsal subcutaneous connective tissue of Wistar albino rats. After 7 and 42 days, the implants with the surrounding tissue were collected, fixed, and processed for histologic evaluation. Sections were evaluated for the presence of inflammatory cells (poly or monomorfonuclear), blood vessels, necrosis area, and thickness of fibrous capsule. Comparisons between groups and time‐periods were performed with Kruskal–Wallis and Mann–Whitney U non‐parametric tests for 5% significance level. No differences in the biocompatibility patterns among the materials for the 2 experimental periods were observed. Independently of the sealer, the tissue behavior showed a tendency to decrease the irritation effect over time. It can be concluded that all sealers are irritant, but its toxicity decreased with time. Endomethásone N showed biocompatible characteristics comparable with those provided by Endofill and Sealer 26. Microsc. Res. Tech. 76:1292–1296, 2013. © 2013 Wiley Periodicals, Inc.     

A SAXS study of the structure of gels formed by mixtures of polyoxyalkylene triblock copolymers

Small‐angle X‐ray scattering was used to characterise aqueous micellar gels of triblock copolymers E₁₃₇S₁₈E₁₃₇, E₈₂S₉E₈₂, E₇₆S₅E₇₆, E₆₂P₃₉E₆₂, and of two mixtures: E₁₃₇S₁₈E₁₃₇ and E₆₂P₃₉E₆₂ (Mix 1) and E₈₂S₉E₈₂ and E₆₂P₃₉E₆₂ (Mix 2), each 50/50 wt%. E = oxyethylene, CH₂CH₂O; S = oxyphenylethylene, OCH₂CH(C₆H₅); and P = oxypropylene, OCH₂CH(CH₃). Within the concentration and temperature ranges investigated (30–40 wt% copolymer, 20–80 °C), spherical micelles of copolymers E₁₃₇S₁₈E₁₃₇, E₈₂S₉E₈₂ and E₆₂P₃₉E₆₂ packed into body‐centred cubic (BCC) structures. Gels of E₇₆S₅E₇₆ were stable only at high concentrations and low temperatures, and a 70 wt% copolymer solution at T = 30 °C formed a hexagonal gel consistent with cylindrical micelles. It is likely that the mixed copolymers would form two distributions of micelles, and more complex structures were expected. However, gels of Mix 2 had well‐ordered BCC structures, while the less ordered gels of Mix 1 were also best characterised as BCC. Copyright © 2006 Society of Chemical Industry     

Modelling of Self-Induced Oscillations in the Mixing Head of a RIM Machine

In this paper, the self-induced oscillations in the mixing head of a RIM machine were modelled. An analytical and simple correlation was derived between the Strouhal number and the averaged pressure drop along the amplitude of the oscillation in the mixing chamber. This correlation theoretically identified that the frequency of the oscillations could be well correlated by the jet Reynolds number, Re_d, and the dimensionless distance between the two jets as proposed by Denshchikov et al., Fluid Dyn. 3 , 460-462 (1983). The flow field dynamics in the mixing head was simulated successfully by Fluent and the computed pressure fluctuations were used to calculate the frequencies of the oscillations in the mixing head. The calculated Strouhal numbers are in good agreement with the dominant frequency from the power spectra of the measured velocity component u_x (Santos, 2003). Finally, the effect of Re_d and Froude number, Fr, on the Strouhal number was investigated in the impingement region. The average Strouhal number showed a decrease with the Reynolds numbers, due to the increasing randomness of flow field in the impingement region. It was also found that the operations at lower values of Fr presented an increasing stability up to the point where the system is unable to present dynamic evolution. The model in this paper provides a theoretical starting point towards understanding of the quantities of the oscillatory flow in the mixing head, as well as a numerical approach to evaluate the dominant frequency in the mixing chamber.     

Residues of different gel formulations on dentinal walls: A SEM/EDS analysis

The aim of this study was to evaluate the presence of residues of sodium hypochlorite gel, chlorhexidine gel, and EDTA gel on dentinal walls after canal preparation through chemical SEM‐ elemental chemical microanalysis (EDS) analysis. Forty‐eight single‐rooted teeth were selected. They had their crowns sectioned and were instrumented with a reciprocating system. The canals were irrigated with 5 mL of saline solution during root canal preparation. After instrumentation, the root canals were irrigated with 3 mL 17% EDTA followed by 1 min of ultrasonic passive activation (3× 20 sec) to remove the smear layer, and then irrigated with 3 mL of saline solution. The specimens were randomized into three groups (n = 12) according to the chemical substance that filled the root canal for 30 min: GI: 5.5% sodium hypochlorite gel; GII: 2% chlorhexidine gel; GIII: 24% EDTA gel; Negative control group: no substance was used. Then, the root canals were irrigated with 6 mL of saline solution followed by 1 min of ultrasonic passive activation (3× 20 sec). After ultrasonic activation, the canals were irrigated with 2 mL saline. The roots were sectioned, and the percentage of each chemical element present in the samples was analyzed through chemical SEM‐EDS microanalysis. All experimental groups showed a significantly higher percentage of chemical elements (Na and/or Cl) than the control group (P < 0.03). This in vitro study has shown that, regardless of chemical solutions used even after the final irrigation protocol, chemical residues of different substances remained attached to the root canal walls. Microsc. Res. Tech. 78:495–499, 2015. © 2015 Wiley Periodicals, Inc.