Residual Stresses Induced by Dry and Cryogenic Cooling during Machining of AZ31B Magnesium Alloy

The major challenge of the Mg alloys has been their unsatisfactory corrosion resistance, which can be enhanced by improving the surface integrity. Cryogenic machining, where liquid nitrogen was used during machining, has been reported to improve the surface integrity of machined components, including compressive residual stresses. This paper analyses the influence of several cutting parameters, tool geometry and cryogenic conditions on the surface and subsurface residual stresses distribution

Potential use of Erica andevalensis and Erica australis in phytoremediation of sulphide mine environments: São Domingos, Portugal

The area around the São Domingos copper mine (Iberian Pyrite Belt) is subject of great environmental concern as acid mine water occurs several kilometres downstream of the mine. In addition thousands of tons of mine waste are present. Erica australis and Erica andevalensis, which are two spontaneous plant species of this area, have been studied with regard to their potential for phytostabilization. Soils and plants from São Domingos and from a reference site (Moreanes) were analysed for soil characteristics, chemical element content in soils (total and AB-DTPA bioavailable fraction) and in plants. Superficial and seepage water as well as waste material leachates were also analysed. Seepage water showed high redox potential (mean 481 mV), high conductivity (mean 4337 μS cm−1) and low pH values (mean 2.6), being classified as mining water. Leachate solutions possessed mainly high levels of Fe, Al and SO42−. Soils in the mining area were highly contaminated in Pb, As and Sb. Locally also high values of Cu and Zn were encountered and the soil available fraction of the majority of the elements showed also quite high values. E. andevalensis grows in soils with pH between 3 and 4, whereas E. australis was only found in soils with pH above 3.5. Both species grow spontaneously in soils, highly contaminated with Pb, As and Sb. These plants, even in the non contaminated soils, are Al-tolerant and Mn-accumulators. In contaminated soils these species are also As-tolerant. Considering the tolerant behaviour in extreme environmental conditions, these Erica species may be of major importance for the recovery of the sulphide mining areas, with climate conditions compatible with its breeding and growing, by physical and chemical stabilization of contaminated soils and even waste material

Reducing social inequalities in the oral health of an adult population

The objective of this study was to evaluate the association between social inequality indicators and oral health conditions in an adult population. This prospective cohort study assessed a probabilistic sampling of adults (aged 20-64 years) living in Piracicaba, São Paulo, Brazil. Oral examinations were performed in 2011 and 2015, conducted at home, and used the decay-missing-filled (DMFT) index of permanent teeth, the Community Periodontal Index (CPI), and the visible biofilm criterion. A questionnaire was administered to determine demographic and socioeconomic aspects and dental services used, and collect oral health-related quality of life (OHRQoL) data. Social inequality indicators were evaluated according to social class (high, middle or low) and type of dental service used (public, health insurance or private), and compared with oral health conditions (visible biofilm, DMFT and incidence of tooth loss, periodontal pockets and bleeding, and OHRQoL), evaluated between 2011 and 2015. Analysis using chi-squared or Fisher tests (p < 0.05) and Cochran's Q test was conducted separately for each category analyzed between 2011 and 2015 (p < 0.05). A total of 143 adults who participated in an earlier study were examined after four years of follow-up. Although the occurrence of oral disease did not decrease over the study period (4 years), there was a reduction in inequality among lower social classes in regard to presence of tooth decay and oral health impact on self-perceived quality of life between 2011 and 2015 (p < 0.05). These results suggest that the Brazilian National Oral Health Policy has achieved its principles, especially that of greater equity33COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2014/15184-22009/16560-0; 2011/00545-

Impact of sense of coherence on oral health-related quality of life among brazilian adults

It has been postulated that oral health-related quality of life (OHRQoL) may be affected by the sense of coherence (SOC), but there are no epidemiological studies investigating this association in Brazilian adults. The present study was conducted among adults of a mid-sized Brazilian city, with the aim of looking into this association. The probability sampling consisted of 342 adults aged 35-44 years old, from a mid-sized Brazilian city, who were examined at their homes for caries (Decayed, Missing and Filled Teeth [DMFT] Index) and periodontal disease (Community Periodontal Index - CPI), according to WHO criteria. The questionnaire applied included demographic factors, socioeconomic information, use of dental services, behavior, SOC and the Oral Health Impact Profile (OHIP). The OHIP outcome, measured by prevalence of the impact, was analyzed by binary logistic regression using a hierarchical approach, a conceptual model, and a 5% significance level. A total of 67.9% of the respondents had one or more impacts on OHRQoL, and 54.4% showed a high SOC. The impact on OHRQoL was more prevalent in adults who had a manual occupation (PR = 2.47, 95%CI 1.24-4.93), those who perceived the need for dental treatment (PR = 2.93, 95%CI 1.67-5.14), and those who had untreated caries (PR = 1.93, 95%CI 1.07-3.47). Those with a low SOC had a twofold higher prevalence of impact on OHRQoL (PR = 2.19, 95%CI 1.29-3.71). This impact on OHRQoL was associated with a low SOC, even after adjusted by socioeconomic, behavioral and clinical factors. Future studies should consider the SOC in determining the oral health impact on quality of life3

Quantum cosmological perfect fluid model and its classical analogue

The quantization of gravity coupled to a perfect fluid model leads to a Schr\"odinger-like equation, where the matter variable plays the role of time. The wave function can be determined, in the flat case, for an arbitrary barotropic equation of state $p = \alpha\rho$; solutions can also be found for the radiative non-flat case. The wave packets are constructed, from which the expectation value for the scale factor is determined. The quantum scenarios reveal a bouncing Universe, free from singularity. We show that such quantum cosmological perfect fluid models admit a universal classical analogue, represented by the addition, to the ordinary classical model, of a repulsive stiff matter fluid. The meaning of the existence of this universal classical analogue is discussed. The quantum cosmological perfect fluid model is, for a flat spatial section, formally equivalent to a free particle in ordinary quantum mechanics, for any value of $\alpha$, while the radiative non-flat case is equivalent to the harmonic oscillator. The repulsive fluid needed to reproduce the quantum results is the same in both cases.Comment: Latex file, 13 page

Superconductivity from correlated hopping

We consider a chain described by a next-nearest-neighbor hopping combined with a nearest-neighbor spin flip. In two dimensions this three-body term arises from a mapping of the three-band Hubbard model for CuO$_2$ planes to a generalized $t-J$ model and for large O-O hopping favors resonance-valence-bond superconductivity of predominantly $d$-wave symmetry. Solving the ground state and low-energy excitations by analytical and numerical methods we find that the chain is a Luther-Emery liquid with correlation exponent $K_{\rho} = (2-n)^2/2$, where $n$ is the particle density.Comment: 10 pages, RevTeX 3.0 + 2 PostScript figs. Accepted for publication in Phys.Rev.

Conception, development and validation of a software interface to assess human’s horizontal intra-cyclic velocity with a mechanical speedo-meter

The aim of this paper was to: (i) calibrate the Swimsportec® speedo-meter; (ii) concept and develop a software’s interface for it (iii) validate the full system. Calibration was done with an industrial robot. The robot arm’s performed a linear and horizontal path at a uniform movement for a set of wide range of velocities (0.5<v<4.5m/s) being the tension data acquire for each specific linear velocity. Software’s interface was developed in LabVIEW® to acquire, display and process pair wises velocity-time data on-line during the subject’s locomotion bout. To transfer data from speedo-meter to the software an acquisition card is used. System validation was done for a set of land-based human locomotion techniques (from slow walk to maximal running) in four subjects and comparing it with a Doppler radar gun. Linear regression models between speedo-meter system and radar gun where very high for both the coefficient of variation of the subject’s velocity within the full gait cycle and his maximal velocity. The 95% of interval confidence agreement limits were very close together in both variables. More than 80% of the Bland- Altman plots were with the 1.96 standard-deviation criteria used on regular basis as rule thumb for techniques validation

Tin distribution in soils and plants, Cistus ladanifer L., in Neves Corvo mining area

The Neves Corvo mining area includes the Mina de Neves Corvo (MNC) that started exploitation in 1988 for Cu and Sn and six abandoned Mn and Cu mines. The Volcano Sedimentary Complex (VSC) which hosts the massive sulphide deposits and the Flysch formations of schist and greywacke dominates the regional geology. The aim of this study was to evaluate tin distribution in soils as well as the capacity to absorb and translocate this element for plants (Cistus ladanifer L.) growing in the MNC area. Samples were collected in two campaigns: the first, for soils, in 1971-72 before MNC existence; and the second campaign (1998), 10 years after mining exploitation began in MNC, for soils and plants in the same places sampled in the first campaign. Soil and plant samples were digested with four acids for total elements extraction and analysed by ICP-AES. The soils developed from Flysch formations have the same average Sn concentrations in both campaigns (2.9 mg kg-1). In contrast, the Sn concentration in soils developed on VSC in the second campaign were twice those (10.4 mg kg-1) from soils of the first campaign (4.5 mg kg-1), reflecting mining. However, tin content in soils developed on both lithologies was considered as a background concentration. Generally, plant roots have higher Sn concentrations than leaves. C. ladanifer plants presented highest Sn concentration than soils suggesting tin accumulation by these plants. The soil pH and solid phases where tin was present were determinant factors for tin uptake and translocation from roots to shoots in C. ladanifer plants

Evaluation of trace elements mobility from soils to sediments between the Iberian pyrite belt and the Atlantic Ocean

An environmental study was conducted in 193 stream sediments and 355 soil samples collected in the lower section of Guadiana River Basin to evaluate the trace elements transfer from one compartment into another. The objective was to evaluate the dispersion of Pb, Cu, Zn and other chemical elements resulting from upstream mines into the lower N-S sector of the Guadiana River Basin to the Atlantic Ocean. The area partly includes the Iberian Pyrite Belt, a known volcanogenic massive sulphide (VMS) province with important mining activity history. Median concentrations of the elements Cu, Pb, Zn, Al, As, Ba, Br, Ca, Mg, Mn and Na are generally higher in the studied sediments than in soils. Soils are normally acidic and mobility of elements is in these conditions higher. When the relations between upstream soils and downstream sediments were established, median values were higher in the upstream soils only for elements such as Co, Ni, K, Pb, Mn and Ti, probably the less mobile, and the Cu, Zn, Al, As, Ba, Br, Ca, Cr, Fe, Mg and Na have highest concentrations in the downstream sediments. Lead was considered the less mobile element and Zn the highly mobile of the base metals in the mining area of the lower Guadiana River. Dispersion of the metals, considering the studied soil and sediment samples is partially restricted to the mining areas or downstream sediments but close to the mine sources, where ore tailings and acid waters occur. Near the mouth, concentrations of As, Cu, Pb and Zn increase in relation with mining and other pollution sources. Interaction with salt water forces chemical elements precipitation from water and subsequent increase of their concentration in sediments. This may be the reason for the increase of those chemical elements concentrations in the sediment

Complex transitions to synchronization in delay-coupled networks of logistic maps

A network of delay-coupled logistic maps exhibits two different synchronization regimes, depending on the distribution of the coupling delay times. When the delays are homogeneous throughout the network, the network synchronizes to a time-dependent state [Atay et al., Phys. Rev. Lett. 92, 144101 (2004)], which may be periodic or chaotic depending on the delay; when the delays are sufficiently heterogeneous, the synchronization proceeds to a steady-state, which is unstable for the uncoupled map [Masoller and Marti, Phys. Rev. Lett. 94, 134102 (2005)]. Here we characterize the transition from time-dependent to steady-state synchronization as the width of the delay distribution increases. We also compare the two transitions to synchronization as the coupling strength increases. We use transition probabilities calculated via symbolic analysis and ordinal patterns. We find that, as the coupling strength increases, before the onset of steady-state synchronization the network splits into two clusters which are in anti-phase relation with each other. On the other hand, with increasing delay heterogeneity, no cluster formation is seen at the onset of steady-state synchronization; however, a rather complex unsynchronized state is detected, revealed by a diversity of transition probabilities in the network nodes