Ammonia effects on proton conductivity properties of coordination polymers

Crystalline metal phosphonates are referred to as a type of structurally versatile coordination polymers [1]. Many of them contain guest molecules (H2O, heterocyclics, etc.), acidic sites and, furthermore, their structure can be also amenable for post‐synthesis modifications in order to enhance desired properties [2]. In the present work, we examine the relationships between crystal structure and proton conductivity for several metal phosphonates derive from multifunctional ligands, such as 5-(dihydroxyphosphoryl)isophthalic acid (PiPhtA) [3] and 2-hydroxyphosphonoacetic acid (H3HPAA). Crystalline divalent metal derivatives show a great structural diversity, from 1D to 3D open-frameworks, possessing hydrogen-bonded water molecules and acid groups. These solids present a proton conductivity range between 7.2·10-6 and 1.3·10−3 S·cm-1. Upon exposure to ammonia vapor, from an aqueous solution, solid state transformations are observed accompanied of enhance proton conductivities. The stability of these solids under different environment conditions (temperature and relative humidities) as well as the influence of the ammonia adsorption on the proton conduction properties of the resulting solids will be discussed.

Ecologia do fitoplâncton em áreas de cultivo de Tilápia do Nilo, Oreochromis niloticus, em tanques-rede no açude Ministro João Alves, Parelhas, Rio Grande do Norte

The dams are limnic ecosystems of great importance for its multiple uses, among them, water supply for the public and to culture of artisanal fish are most relevant. The aim of the present study is to evaluate the physical-chemical characteristics and the phytoplankton community in two chosen sites (Point 1 littoral zone of point source; Point 2 pelagic zone of non-point source) of the Minister João Alves dam, which is also known as Boqueirão de Parelhas/RN. This represents the spatial distribution of the phytoplankton species in order to understand any possible alterations of the water quality and the phytoplankton composition in relation to the water quality originating from the impact of the tilapia, Oreochromis niloticus, culture. The study period also encompasses temporal variations exhibited in two seasons of an annual cycle, one during the dry season (Oct, Nov and Dec of 2008 and Jan of 2009), and the other rainy season (Mar, Apr, May and June of 2008) to extend the observation. The physicalchemical parameters, such as pH, temperature, electrical conductivity, concentration of dissolved oxygen were measured in situ and the values of the inorganic nutrients (nitrate, ammonium and orto-phosfato) and chlorophyll in the laboratory. The quali-quantitative analyses of the phytoplankton had been carried through sedimentation technique and the enumeration of the random of 400 cells, colonies and filaments counted using Sedgwick-Rafter counting chamber. The results of pH varied widely from the acidic to alkaline range with the minimum of 5.8 (± 0.8) and the maximum of 9.2 (± 0.7-0.8), at point 1 and 2. The dissolved oxygen content was higher in the rainy period than that in the dry period. The maximum electrical conductivity was of 1409 μScm-1 in point 1 and 431 minim of μScm-1, in point 2. There was a considerable alteration in the levels of inorganic nutrients such as nitrate-nitrogen, ammoniacal nitrogen and orthophosphate during the two cycles of study period. Phytoplankton assemblages presented a picture of alternate dominance among species Cyanobacteria, Bacillariophyceae and Chlorophyceae. The trophic state index diagnosed to the category of mesotrophic, which is based on the values of chlorophyll, total phosphorus and Secchi-disc measurements. The wind driven turbulence of the water column and the fresh inflow of water (flushing and dilution) during rainy season acted as constraint and did-not allow an exaggerated growth of the species of cyanobacteria. On the basis of the present we conclude that the culture of tilapias in cage-culture fails to produce pollution load that could compromise the quality of the water of the dam, probably be due to small dimension of the culture in relation to the size, volume of the water and the reservoir capacity support its own environment

Durability in concrete : new instruments : new opportunities

New infrastructure, particularly in the developing countries, demands substantial capital investment and a loss of durability of the concrete means a waste of oportunity. Improving durability of concrete structures is a non-trivial task. The durability of concrete has been related to its ability to resist the transport of water and the potentail imporvements to concrete durability using supplementary cementitious materials (SCM) has been well documented. With access to neutron and synchrotron facilities it has become possible to; (a) measure the ability of SCM to inhibit transport of water in concrete (b) measure particle size increase of hydrating cements (with and without SCM) by ultra-small angle neutron scattering (c) use neutron tomography combined with x-ray tomography to determine the three dimensional flaws in the structure of concretes that enable water ingress into structures, and (d) determine the amount of curing or degree of hydration on the durability of SCM/OPC blends. This review will detail preliminary results on cement and concrete obtained using the newly available neutron, synchrotron and other facilities in Australia and Brazil and highlights their ability to estimate factors which determine the service life of concrete

Barriers to implementing reverse logistics in South Australian construction organisations

Purpose - This paper aims to present a survey of the perceptions of the barriers to implementing reverse logistics (RL) practices in South Australian (SA) construction organisations. Despite the extensive research on forward logistics and RL, there is a paucity of studies that examine the barriers to implementing RL particularly within the Australian construction industry. This study builds on the ongoing research being undertaken by the authors, entitled “Designing for reverse logistics (DfRL) within the building life cycle: practices, drivers and barriers”, which is examining the best practices and drivers that could be used as a “road map” for developing appropriate solutions for the successful implementation of RL. Design/methodology/approach - Data were collected by utilising a triangulated data collection approach, a literature review and 49 questionnaires. The review of the literature identified 16 barriers to implementing RL. The quantitative survey data were subjected to descriptive and inferential statistics with correlation analysis to examine the relationships between different pairs of variables comprising RL’s critical barriers. Findings - The following barriers were indicated as most significant: lack of incorporation of salvaged materials by designers; regulation restrictions to usage of recovered materials and components; potential legal liabilities; higher costs; and longer-time association with deconstructing buildings. The least ranked barriers were mostly drawn from the operational and industrial categories as being: organisational lack of support for deconstruction due to incompatible design; lack of organisational support for deconstructing buildings due to higher health and safety risks; and inadequate skills and experience for deconstruction (operational). The industrial barrier was related to “higher costs of salvaged materials in comparison to virgin products”. Research limitations/implications - First, the reported findings are focussed on one study that used questionnaire surveys within the construction industry; therefore, the results may not be generalisable to other contexts. Further, studies should be conducted and extended to other industrial sectors beyond the construction industry. Second, the quantitative study (n 49) used a smaller sample, and the survey items were based on the review of the literature. Practical implications - The identified barriers could be used as a “road map” for the development of appropriate solutions for the successful implementation of RL, and to improve the environment-related decision-making processes of contractors. Originality/value - This study makes a contribution to the body of knowledge on the subject of RL within a previously unexplored SA context. In addition, the study provides some insights on the contributory effects of the barriers to the implementation of RL. It is the first work undertaken to determine the barriers to the adoption of RL within the SA construction industry.

Drivers for adopting reverse logistics in the construction industry : a qualitative study

Purpose - The purpose of this paper is to investigate and analyse the perceptions of South Australian construction practitioners on drivers affecting the implementation of reverse logistics (RL). In this context, RL is defined as the process of moving goods from their typical final destination for the purpose of capturing value or ensuring proper disposal.

Design/methodology/approach - Semi-structured interviews were conducted with eight practitioners to collect data and the interview transcripts were analysed using the NVivo (version 10) package. Cluster analysis was used to cross-validate the findings and provide an in-depth insight into the findings.

Findings - The findings indicate that most of the drivers identified in earlier research are relevant for the construction industry. In addition, the study identified some new drivers that are categorised as "targeted demands by an exclusive clientele". These drivers were found to be complementary to the economic, environmental and social drivers as previously conceptualised. In addition, a set of factors affecting the strength of drivers that had been overlooked in previous studies emanated from the interview analysis. These include the type of project and the attributes of clients, both of which strongly affect the drivers of RL implementation in construction.

Research limitations/implications - The major limitations are the relatively small size of the sample of interviewees and having interviewees from one geographic area with specific socio-economic characteristics.

Practical implications - The identified drivers and the clustering of RL themes could be used by practitioners as a "road map" for the development of appropriate solutions to successfully promote RL within the construction industry. Organisational energies could thus be channelled towards the drivers that need the most improvement.

Originality/value - The study contributes to this research sphere by employing cluster analysis to customise and contextualise the drivers that were previously identified. The study goes beyond the extant literature by discovering the prominent effects of these drivers on the impact of targeted demands by an exclusive clientele. This could be of great value in terms of creating avenues for future investigations on the topic.

Unmasking of the trigemino-accessory reflex in accessory facial anastomosis

To evaluate the possible blink reflex responses in facial muscles reinnervated by the accessory nerve. Method: Eleven patients with a complete facial palsy were submitted to a surgical repair by an accessory facial nerve anastomosis (AFA). In this pathological group, blink reflex was studied by means of percutaneous electrical stimulation of the supraorbital nerve and recording from the orbicularis oculi muscle. A control group comprised seven normal people and seven patients with a complete Bell's facial palsy; in this group, responses on the sternocleidomastoideus (SCM) muscles were studied after supraorbital nerve stimulation. Results: All the patients with AFA showed a consistent degree of facial reinnervation. Ten out of the 11 patients with AFA showed reflex responses; in six, responses were configured by a double component pattern, resembling the R1 and R2 components of the blink reflex; three patients had an R1-like response and one patient showed a unique R2 component. Mean values of latencies were 15.2 (SD 4.6) ms for the R1 and 85.3 (SD 9.6) ms for the R2. In the control group, eight out of 14 people had evidence of reflex responses in the SCM muscles; these were almost exclusively configured by a bilateral late component (mean latency 63.5 (SD 15.9) ms) and only one of the subjects showed an early response at 11 ms. Conclusion: The trigemino-accessory reflex response in the pathological group was more complex and of a significantly higher incidence than in the control group. These differences could be tentatively explained by a mechanism of synaptic plasticity induced by the impairment of the efferent portion of the reflex. This could unmask the central linking between the trigeminal and the accessory limbs of the reflex. The findings described could be a demonstration of neurobionomic function in the repairing process of the nervous system.

The Power of the Synthetic Control Method

The synthetic control method (SCM) is a new, popular method developed for the purpose of estimating the effect of an intervention when only one single unit has been exposed. Other similar, unexposed units are combined into a synthetic control unit intended to mimic the evolution in the exposed unit, had it not been subject to exposure. As the inference relies on only a single observational unit, the statistical inferential issue is a challenge. In this paper, we examine the statistical properties of the estimator, study a number of features potentially yielding uncertainty in the estimator, discuss the rationale for statistical inference in relation to SCM, and provide a Web-app for researchers to aid in their decision of whether SCM is powerful for a specific case study. We conclude that SCM is powerful with a limited number of controls in the donor pool and a fairly short pre-intervention time period. This holds as long as the parameter of interest is a parametric specification of the intervention effect, and the duration of post-intervention period is reasonably long, and the fit of the synthetic control unit to the exposed unit in the pre-intervention period is good.

Synthetic portfolio for event studies: Estimating the effects of volatility call auctions

We propose a method denoted as synthetic portfolio for event studies in market microstructure that is particularly interesting to use with high frequency data and thinly traded markets. The method is based on Synthetic Control Method and provides a robust data driven method to build a counterfactual for evaluating the effects of the volatility call auctions. We find that SMC could be used if the loss function is defined as the difference between the returns of the asset and the returns of a synthetic portfolio. We apply SCM to test the performance of the volatility call auction as a circuit breaker in the context of an event study. We find that for Colombian Stock Market securities, the asynchronicity of intraday data reduces the analysis to a selected group of stocks, however it is possible to build a tracking portfolio. The realized volatility increases after the auction, indicating that the mechanism is not enhancing the price discovery process.