Impact of gonadectomy on blood pressure regulation in ageing male and female rats

Sexual dimorphism in blood pressure has been associated with differential expression of the angiotensin II (AII) receptors and with activity of the nervous system. It is generally accepted that aging affects kidney function as well as autonomic nervous system and hormonal balance. Given that hypertension is more prevalent in men than women until women reach their seventh decade we hypothesised that females would be relatively protected from adverse effects of ageing compared to males, and that this would be mediated by the protective effect of ovarian steroids. Intact and gonadectomised male and female normotensive Wistar rats aged 6, 12 and 18 months were used to study renal function, blood pressure, heart rate and blood pressure variability. We observed that intact females had lower levels of proteinuria and higher (12.5%) creatinine clearance compared to intact males, and that this difference was abolished by castration but not by ovariectomy. Ovariectomy resulted in a change by 9% in heart rate, resulting in similar cardiovascular parameters to those observed in males or gonadectomised males. Spectral analysis of systolic blood pressure revealed that high frequency power spectra were significantly elevated in the females vs. males and were reduced by ovariectomy. Taken altogether the results show that females are protected from age-related declining renal function and to a lesser extent from rising blood pressure in comparison to males. Whilst ovariectomy had some deleterious effects in females, the strongest effects were associated with gonadectomy in males, suggesting a damaging effect of male hormones

Nucleation of amorphous precursor in magnesium phosphate cements: Clues to the reaction pathway

In-situ X-ray techniques indicated that in its early stages, the reaction pathway of magnesium phosphate cements involves the formation of an amorphous precursor, first detected as nanoparticles which organize themselves into larger domains. Crystallization occurs from this precursor (already containing the structural motives of the crystalline counterpart) by increasing the long-range order through relatively minor structural rearrangements. The process is compatible with multi-steps nucleation involving non-classical mechanisms, as observed in Ca-carbonates and phosphates, therefore, indicating ways to control the transformation to improve cement design

Influence of additions of synthetic anhydrous calcium carbonate polymorphs on nanolime carbonation

The influence of synthetic anhydrous calcium carbonate polymorphs, calcite, vaterite and aragonite, on carbonation of nanolime suspension, has been investigated. The higher rates of carbonation observed after 7 days in mixtures containing vaterite and aragonite particles, found explanation in the control exerted by heterogeneous nucleation on the water-mediated reaction mechanism and in the enhanced carbon dioxide diffusivity in the sample volume, both facilitated by the higher specific surface of the powders and the microporous sample fabric. Introduction of synthetic calcium carbonate allowed for exerting control on formed polymorphs, subverting the order of their (meta-)stability. The peculiar microstructure obtained by adding aragonite rod-like particles, mitigates the propagation of desiccation cracks (which impair continuity of the carbonated nanolime film). The mechanism, although still not completely understood, likely involves the regulation of evaporation of liquid fraction and redistribution of the tensional stresses during drying and nanolime crystallization. The obtained results provide new insights into the crystallization of carbonates from nanolime particles and may help in the design of innovative compatible products for consolidation of lime-based materials and carbon dioxide sequestration

Physical-chemical-mechanical quantitative assessment of the microstructural evolution in Portland-limestone cement pastes exposed to magnesium sulfate attack at low temperature

The changes in structural integrity and microstructure of Portland-limestone cement pastes were investigated in the course of magnesium sulfate attack at low temperature. A deterioration front, consisting of three distinct layers (brucite, gypsum, leached cement matrix), swelled in time due to the expansive nature of the deterioration products, generating cracks and subsequently detaching from the sound cement matrix, continuously promoting the process. Gypsum and thaumasite characterized the leached matrix, which experienced extensive cross-linking of the aluminosilicate structures, as a result of decalcification and dealumination of the calcium silicate hydrates (C[sbnd](A[sbnd])S[sbnd]H), impairing the overall mechanical performance. C[sbnd]S[sbnd]H of low packing density was most severely affected by the process, as confirmed by the significant drop in nano-mechanical properties. The increased rate of deterioration with limestone content was tentatively attributed to the prevalent morphology of the C[sbnd]S[sbnd]H phase. Results were validated by thermodynamic simulations, indicating that the real systems did not reach equilibrium

Biofiltration of wastewater treatment plant effluent: Effective removal of pharmaceuticals and personal care products and reduction of toxicity

This study investigates biofiltration for the removal of dissolved organic carbon (DOC), pharmaceuticals and personal care products (PPCPs), and for the reduction of non-specific toxicity expressed as baseline toxicity equivalent concentration (baseline-TEQ). Two filtering media, sand and granular activated carbon, were tested. The influence of pre-ozonation and empty-bed contact time (EBCT, from 30 to 120 min) was determined. The experiments were performed at a pilot-scale with real WWTP effluent. A previous study showed that biological activity had developed on the filtering media and dissolved organic removal had reached a steady state before sampling commenced. The results show that biological activated carbon (BAC) has a good potential for the removal of DOC (35–60%), PPCPs (>90%) and baseline-TEQ (28–68%) even without pre-ozonation. On the contrary, the sand shows limited improvement of effluent quality. Varying the EBCT does not influence the performance of the BAC filters; however, dissolved oxygen concentration could be a limiting factor. The performances of the BAC filters were stable for over two years suggesting that the main mechanism of organic matter and PPCPs removal is biodegradation. It is concluded that BAC filtration without pre-ozonation could be implemented as a low cost advanced treatment option to improve WWTP effluent chemical quality

Magnezowo-fosforanowe wyroby ceramiczne wytwarzane z produktów termicznej transformacji cementu - azbestów

According to recent European directives, the need for environmentally friendly alternative solutions to landfill disposal of hazardous wastes, such as asbestos-containing materials, prompts their recycling as secondary raw materials. In this work, magnesium phosphate ceramics were prepared using the product of inertization of cement-asbestos. Magnesium phosphate ceramics show interesting properties like good water resistance and high strength that make them attractive materials for several applications. Asbestos containing materials were mixed with magnesium carbonate and annealed at two different temperatures (1100 and 1300 ºC). During thermal treatment complete destruction of asbestos minerals with their transformation into new phases, and crystallization of MgO from magnesium carbonate decomposition, occurs. Upon addition of potassium di-hydrogen phosphate and water, the magnesium oxide in the product of thermal treatment, contributes to the onset of a setting reaction whose product is magnesium potassium phosphate hydrate. The reactivity of periclase was found to be dependent on the calcination temperature. Lower reaction rates were observed for the MgO obtained at lower temperature. The setting reaction of the magnesium phosphate ceramic has been followed in time up to 6 months by means of the X-rays powder diffraction trechnique. Quantitative phase analysis was performed using the Rietveld method and both crystalline and amorphous phases were quantified. The amount of magnesium potassium phosphate was found to increase with time, and was accompained by a decrease in the amount of the amorphous fraction. This fact supports the hypothesis of the formation of an amorphous precursor of the crystalline MKP during the hydration reaction. SEM images showing elongated magnesium potassium phosphate hydrate crystals emerging from what appears as an amorphous matrix, further confirms this view. Since the mechanical properties of magnesium phosphate ceramics are known to increase with time, we can conclude that the main contribution to the development of strenght comes from the crystalline magnesium potassium phosphate hydrate. In this work, we describe a procedure for simultaneous destruction of asbestos minerals and formation of cementitious compounds, which represents a recycling opportunity for this class of hazardous wastes, bringing benefits in terms of energy requirements and preservation of natural resources in cement manufacturing.Zgodnie z niedawnymi dyrektywami europejskimi, potrzeba przyjaznego dla środowiska alternatywnego rozwiązania usuwania odpadów niebezpiecznych, takich jak materiałów zawierających azbest, pobudza ich ponowne wykorzystanie jako surowców wtórnych. W tej pracy, magnezowo fosforanowe wyroby ceramiczne zostały wytworzone z użyciem produktów inertyzacji cementu – azbestu. Magnezowo fosforanowe wyroby ceramiczne wykazują interesujące właściwości takie jak dobry opór wodny oraz duża wytrzymałość, co sprawia, że są atrakcyjnym materiałem dla wielu aplikacji. Materiały zawierające azbest zostały zmieszanie w węglanem magnezu i wyżarzone w dwóch różnych temperaturach (1100°C i 1300°C). Podczas obróbki cieplnej następuje całkowite zniszczenie minerałów azbestu wraz z ich transformacją w nowe fazy, oraz krystalizacja MgO z rozpadu węglanu magnezu. Podczas dodawania diwodorofosforanu magnezu do wody, tlenek magnezu jako produkt obróbki cieplnej, przyczynia się do rozpoczęcia reakcji wiązania, której produktem jest hydrat fosforanu magnezu i potasu. Odkryto, że reaktywność peryklazu zależy od temperatury kalcynacji. Niższa szybkość reakcji została zaobserwowana dla MgO uzyskanego w niższej temperaturze. Reakcja wiązania wyrobów ceramicznych magnezowo fosforanowych została przeprowadzona w czasie do 6 miesięcy za pomocą techniki rentgenowskiej dyfrakcji proszkowej. Ilościowe analizy fazowe zostały wykonane z użyciem metody Rietvelda i obliczono zarówno fazę krystaliczną jak i amorficzną. Zauważono, że ilość fosforanu magnezowo potasowego zwiększa się w czasie, i że towarzyszy jej spadek ilości części amorficznej. Fakt ten potwierdza hipotezę powstawania amorficznego prekursora krystalicznego fosforanu magnezowo potasowego podczas reakcji hydracji. Obrazy SEM przedstawiają wydłużone kryształy hydratu fosforanu magnezowo potasowego wyłaniające się, z wyglądającej na amorficzną, macierzy, następnie ten wygląd się potwierdza. Ponieważ wiadomo, że właściwości mechaniczne fosforanu magnezu zwiększają się z czasem, możemy wnioskować, że główny wpływ na zwiększenie się wytrzymałości ma krystaliczny hydrat fosforanu magnezowo potasowego. W pracy tej opisano procedurę jednoczesnego rozpadu minerałów azbestu i tworzenia się związków cementytowych, co wskazuje na możliwość powtórnego przetworzenia tego rodzaju odpadów niebezpiecznych, co przynosi korzyści w kategoriach zapotrzebowania energetycznego i ochrony zasobów naturalnych w przetwórstwie cementu

Characterization of by-products from the combustion of solid fuels with SEM/EDS and micro-Raman spectroscopy

Coal is still one of the main sources of energy for producing electricity. The environmental impact of the solid products resulting from coal combustion (fly ashes) is mitigated by employing them as secondary raw materials. Their chemical and physical properties are strongly dependent upon the type of coal and the burning plant technology, making their characterization an essential prerequisite for recycling. In recent years, there has been also a concomitant increase in the amount of ashes produced from biomass combustion. Structurally and chemically different, they pose different problems in terms of ecological impact: one of the most relevant is the concentration of heavy metals. In this work, two samples from the combustion of coal and lignite, and two samples from the combustion of biomass, namely straw and hay, have been investigated by means of scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) and micro-Raman spectroscopy (with laser wavelength 532 nm). Raman spectroscopy, with the aid of the optical microscope, allowed for addressing the laser beam on specific crystals for phase identification at the micrometric scale [1]. X-ray diffraction (XRD) was employed for bulk qualitative analysis of the crystalline fraction. Due to the operating temperatures above 1400 °C, fly ashes from coal combustion showed the presence of partly glassy spherical bodies (around 10 μm in diameter) with alumino-silicate composition. Crystallization of mullite (ideal Al6Si2O13) from the mass was documented. Euhedral to pseudoeuhedral iron oxide crystals were found as a ’coating’ on some these particles, suggesting ’condensation’ at the grain surface. Their presence in the mass is also an indication of their crystallization from the glass during cooling. These findings are in agreement with XRD results, showing mainly mullite, hematite (Fe2O3) and quartz. Ashes from the combustion of biomass consist mainly of unburned fuel residues, that represent up to 25% in weight. Silica is about 40% in weight and is mainly concentrated in spherical glassy-like particles from nanometric to micrometric in size. Both types of ashes from biomass are high in potassium and phosphates. Typical phases detected by XRD are Arcanite (K2SO4) and Monetite Ca(HPO4). Implications for the use of these by-product as secondary raw materials will be discussed

Recovery of a freshwater wetland from chemical contamination after an oil spill

In March 2009, a cargo ship spilled 250 tons of heavy fuel oil off the Queensland coast of Australia. The pristine National Park Moreton Island, seven nautical miles to the east of the spill site, was most affected by the oil slick. Contamination of the island's shoreline was widespread, with freshwater wetlands particularly slow to recover as clean-up needed to be carefully managed to avoid damage to this sensitive ecosystem. During the clean-up process on Moreton Island a monitoring program was initiated using traditional chemical analysis in combination with bioanalytical techniques to assess the extent and variability in contamination at sites on the shoreline and freshwater wetlands. Water accommodated fractions (WAF) of oil residues from samples taken directly after the spill on the shoreline showed the same level of toxic potency as samples from the wetland while baseline-toxicity equivalent concentrations (baseline-TEQ) and 2,3,7,8-tetrachlorodibenzodioxin equivalent concentrations (TCDDEQ) were much lower in oil collected from the sandy beach. The umuC assay for genotoxicity and the E-SCREEN assay for estrogenic effects indicated the extracts were not genotoxic or estrogenic. PAH concentrations and toxicity in grab water samples were below detectable levels, however, extracts from time integrated silicone passive samplers deployed for several weeks at the contaminated sites gave measurable responses in the bioassays with TCDDEQ levels increased relative to the control site. The low levels of baseline-TEQ and TCDDEQ present after 8 months had further decreased 6 months later indicating satisfactory recovery of this pristine ecosystem after an oil spill. © 2011 The Royal Society of Chemistry