Characteristics of effluents from healthcare waste treatment with alkaline hydrolysis

Although alkaline hydrolysis emerges as an alternative process to treat healthcare waste (HCW), information about its emissions is scarce, namely as regards effluents production. This work aims to characterize the effluents from alkaline hydrolysis tests with samples of components usually present in HCW, under a temperature of 110°C and with 1 M NaOH aqueous solutions. Some of the regulatory parameters for discharging effluents were determined; also, tests for assessing aerobic and anaerobic biodegradation of those effluents were carried out. The effluents showed values lower than threshold values for almost all the parameters except pH, total nitrogen, TOC, COD and BOD₅. Although with high organic load, the effluents from discarded medical components (DMC) and animal tissues (AT) showed a percentage of aerobic biodegradation of 50.5 and 52.9%, respectively. The anaerobic biodegradability obtained for the effluents from DMC were 22.3 and 42.2% for those with AT.     

Freshwater molluscs from volcanic areas as model organisms to assess adaptation to metal chronic pollution

Cellular biomarkers of exposure and biological effects were measured in digestive gland of snails (Physa acuta) sampled in sites with and without active volcanism in S?o Miguel Island (Azores). Metal content in digestive cell lysosomes was determined by image analysis after autometallography (AMG) as volume density of autometallographed black silver deposits (Vv(BSD)). Lysosomal structural changes (lysosomal volume, surface and numerical densities - Vv(LYS,) Sv(LYS) and Nv(LYS-), and surface-to-volume ratio - S/V(LYS)-) were quantified by image analysis, after demonstration of beta-glucuronidase activity, on digestive gland cryotome sections. Additional chemical analyses (atomic absorption spectrophotometry) were done in the digestive gland of snails. The highest metal concentrations were found in snails from the active volcanic site, which agreed with high intralysomal Vv(BSD). Digestive cell lysosomes in snails inhabiting sites with active volcanism resembled a typical stress situation (enlarged and less numerous lysosomes). In conclusion, the biomarkers used in this work can be applied to detect changes in metal bioavailability due to chronic exposure to metals (volcanism), in combination with chemical analyses.     

Envelope index evaluation model of existing buildings

An evaluation methodology to estimate the envelope's degradation level (DL) of social housing buildings was developed. The DL of each of the principal faults was determined as well as the building envelope's evaluation index (EI). Degradation assessment results were obtained through visual survey and were aggregated by a method developed in the research. With the aim of discovering the visual phenomena's underlying mechanism, models have been constructed to analyse the behaviour of each dependent variable (faults), according to the independent ones: building age, covering type, last repair action and proximity to sea, trees, main roads, industrial zones and collective buildings. After obtaining the building's EI, models were developed to estimate the influence of the predictor variables in this index. The aim of this paper is to present the models for obtaining the envelope EI of a set of social residence buildings in Aveiro District, Portugal. This was achieved in the scope of a research project on prioritising refurbishment interventions in the Portuguese social housing stock [Rodrigues, M.F.S., 2008. Social Housing Conservation State. Evaluation index and methodology. PhD Thesis, Universidade de Aveiro, Aveiro (in Portuguese)].     

Impact of medical waste incineration in the atmospheric PCDD/F levels of Porto, Portugal

As a consequence of a monitoring program of a new municipal waste incinerator initiated in 1998, a large data-base of dioxin and furan concentrations in the atmosphere of the metropolitan area of Porto, in northern Portugal, has been collected. The existence of this data coincides with the shutdown in January 2001 of two medical waste incinerators that were under operation in the inner city of Porto. Dioxin emissions from these facilities were measured indicating emissions 100 to 1000 times larger than recent European Union directive limits. Data show that the shutdown of these two units had a clear effect on the improvement of air quality in the region that was observed either on the overall level of dioxins and furans or as in subtle alterations of the homolog pattern of these compounds in the atmosphere.     

Nuclear microscopy of rat colon epithelial cells

Using Nuclear microscopy, we have investigated iron distributions in the colons of Sprague Dawley rats, in order to elucidate heme uptake. Four groups of five Sprague Dawley rats (mean weight 180 g) were fed different purified diets containing either heme diet (2.5% w/w hemoglobin), high fat diet (HFD) (18% w/w fat, 1% w/w cholesterol), ‘western’ diet (combination of hemoglobin 2.5% and 18% fat, 1% cholesterol) or control diet (7% w/w fat). After 4 weeks, animals were sacrificed by exsanguination after anaesthesia.Thin sections of frozen colon tissue were taken, freeze dried and scanned using nuclear microscopy utilising the techniques PIXE, RBS and STIM. The new data acquisition system (IonDaq) developed in CIBA was used to obtain high resolution images and line scans were used to map the iron distributions across the colon boundaries.The nuclear microscope results indicate that when HFD is given in addition to heme, the iron content of the epithelial cells that line the colon decreases, and the zinc in the smooth muscle wall increases. This implies that the level of heme and fat in diet has an important role in colon health, possibly by influencing epithelial cells directly or changing luminal composition such as bacterial flora or levels of metabolites and cytotoxins.     

Analysis of a rate-based feedback control strategy for long haul data transport

Digital communication has become fast enough so that the speed of light has become a bottleneck. For example, the round trip transcontinental [USA] delay through a fiber link is approximately 0.04 s; at 150 Megabit/s, a source needs to transmit approximately 8,000,000 bits during one round trip time to utilize the bandwidth fully. As the service rates of queues get large, the time scales of congestion in those queues decrease relative to the round trip time, making the dual goals of keeping buffers small and utilizations high even more difficult to achieve. In this paper we analyze a class of delayed feedback schemes that achieve these goals despite propagation delays and regardless of network rates. We analyze the delayed feedback schemes as a system of delay-differential equations, in which we model the queue-length process and the rate at which a source transmits data as fluids. We assume that a stream of acknowledgements carries information about the state of a bottleneck queue back to the source, which adapts its transmission rate according to any monotone function of that state. We show stability for this class of schemes, in that their rate of transmission and queue length rapidly converge to a small neighborhood of the designed operating point. We identify the appropriate scaling of the model's parameters, as a function of network speed, for the system to perform optimally: with a deterministic service rate of μ at the bottleneck queue, the steady state utilization of the queue is and steady state delay is . We also describe the transient of behavior of the system as another source suddenly starts competing for the bandwidth resources at the bottleneck queue. This work directly applies to the adaptive control of Frame Relay and ATM networks, both of which provide feedback to users on congestion.     

Calcium silicate cements obtained from rice hull ash: A comparative study

This work describes the utilization of rice hull as raw-material for the preparation of two calcium silicates namely, β-Ca_1.91Ba_0.04SiO₄ and β-Ca_1.96Ba_0.04SiO₄. The synthesis was completed at 800°C. Hydration rate and compressive strength of mortars prepared with the two calcium silicates were studied and compared to mortars prepared with commercial Portland cement. Hydration rates for both silicates, studied by thermogravimetric and FTIR analysis are very similar; after 60 days the hydration rates are around 42–43% and reaches 75% after 270 days. Compressive strength experiments were performed using test specimen prepared with commercial Portland cement as reference, and blends of Portland cement and the two calcium silicates, at replacement levels of 10 and 20%. Results have shown that after a 90 days curing period, the compressive strength of the reference and the blends containing 10% of each of the calcium silicates show the same behavior. Using a replacement level of 20% there is a small decrease in compressive strength. This behavior is attributed to the lower hydration rate of these calcium silicates.     

Diffusion of Water through Poly(styrenesulfonate) membranes produced from the sulfonation of wasted PS plastic cups

Summary Two urethane carbazolyldiacetylenes, 6-(N-Carbazolyl)hexa-2,4-diyn-1-ol-1acetate buthyl urethane and 9-(N-carbazolyl)nona-5,7-diyn-1-ol-acetate buthyl urethane (hereafter named CHBU and CNBU, respectively), which present methylene spacers with different length between the urethane and diacetylene moieties, have been synthesized in order to obtain a conjugated polymer for non linear optics. The UV polymerization is studied by UV-Vis spectroscopy in polymeric films prepared by mechanical alignment of the monomer powder on hot substrates followed by UV polymerization. PolyCHBU films containing residual monomer exhibit thermochromic properties from blue to red form while no spectroscopic changes are observed for the polyCNBU films upon temperature. For polyCHBU, both blue and red films present also optical dichroism as observed by polarized UV-Vis spectroscopy, polarized microscopy and AFM.