Biocompatibility of New Calcium Aluminate Cement (Endo Binder)

Introduction: The purpose of this study was to evaluate the biocompatibility of calcium aluminate cement (EndoBinder) in subcutaneous tissue of rats. Methods: Fifteen rats, weighing 300 g, were separated into 3 groups (n = 5) in accordance with the time of death (7, 21, 42 days). Two incisions were made in the dorsal subcutaneous tissue of each rat in which were implanted 2 polyethylene tubes filled with the test materials, Endo Binder (EB) and Grey MTA (GMTA). The external tube walls were considered the negative control group (CG). After 7, 21, and 42 days, animals were killed, obtaining 5 samples per group, at each time interval of analysis. Results: From the morphologic and morphometric analyses by using a score of (0-3) (50, 100, and 400x), results showed absence of inflammatory reaction (0) for EB after 42 days. However, for GMTA, a slight inflammatory reaction (1) was observed after 42 days, which means the persistence of a chronic inflammatory process. When compared with CG, tissue reaction ranging from discrete (1-7 days) to absent (0-42 days) was observed. Conclusions: EndoBinder presented satisfactory tissue reaction; it was biocompatible when tested in subcutaneous tissue of rats. (J Endod 2012;38:367-371)

Rice husk derived waste materials as partial cement replacement in lightweight concrete

In this study rice husk ash (RHA) and broiler bed ash from rice husk (BBA), two agricultural waste materials, have been assessed for use as partial cement replacement materials for application in lightweight concrete. Physical and chemical characteristics of RHA and BBA were first analyzed. Three similar types of lightweight concrete were produced, a control type in which the binder was just CEMI cement (CTL) and two other types with 10% cement replacement with, respectively, RHA and BBA. All types of similar lightweight concrete were prepared to present the same workability by adjusting the amount of superplasticizer. Properties of concrete investigated were compressive and flexural strength at different ages, absorption by capillarity, resistivity and resistance to chloride ion penetration (CTH method) and accelerated carbonation. Test results obtained for 10% cement replacement level in lightweight concrete indicate that although the addition of BBA conducted to lower performance in terms of the degradation indicative tests, RHA led to the enhancement of mechanical properties, especially early strength and also fast ageing related results, further contributing to sustainable construction with energy saver lightweight concrete.

Lanthanum carbonate, like sevelamer-HCl, retards the progression of vascular calcification and atherosclerosis in uremic apolipoprotein E-deficient mice

Atherosclerosis and vascular calcification (VC) progression in chronic kidney disease is favored by disturbances of mineral metabolism. We compared the effect of phosphate binder lanthanum (La) carbonate with sevelamer-HCl on atherosclerosis, VC and bone structure and function in mice with chronic renal failure (CRF). Apolipoprotein E-deficient (apoE(-/-)) mice were randomized to one non-CRF and three CRF groups, fed with standard diet (one non-CRF and one CRF) or diet supplemented with either 3% lanthanum carbonate (La3%) or 3% sevelamer-HCl (Sev3%). Both La3% and Sev3% supplemented CRF mice displayed a decrease of serum phosphorus, calcification at both intimal and medial aortic sites and atherosclerosis. This was associated with a reduction of plaque Type I collagen expression by both binders and of positive nitrotyrosine staining in response to sevelamer-HCl only. Increased mineral apposition and bone formation rates in unsupplemented CRF mice were reduced by Sev3% but not by La3%. The beneficial effects of La carbonate and sevelamer-HCl on the progression of VC and atherosclerosis in CRF mice could be mainly due to a decrease in phosphate retention and likewise a reduction of arterial Type I collagen expression. The effect of La carbonate differed from that of sevelamer-HCl in that it did not appear to exert its vascular effects via changes in oxidative stress or bone remodeling in the present model.

Comparison of the n-Alkanes and Polycyclic Aromatic Hydrocarbons Concentrations in the Atmosphere during the Preparation of Warm and Hot Mixtures Asphalt for Pavements

Asphalt binder is used in the production of hot mixes asphalt (HMA) for paving and, due to the high temperatures used, generates fumes thatcontainn-alkanes and polycyclic aromatic hydrocarbons (PAH). Asphalt mixes prepared at lower temperatures, such as warm mixes asphalt (WMA), may contribute to reduce the emissions of those compounds and save energy. This paper investigatesn-alkanes and PAH in the total suspended particles during the preparation of WMA, in comparison with HMA, in laboratory. The results showed that the n-alkanes of the WMA and HMA presented C-max at n-C-26 and n-C-28, respectively; also, the total content of n-alkanes was higher for the HMA than forthe WMA. Besides, benzo[b]fluoranthene and benzo[a]anthracene were the major PAH in the WMA, while the higher temperatures of the HMA were observed to volatilize all larger PAH, demonstrating higher potential of inhalation exposure.

Novel properties of melanins include promotion of DNA strand breaks, impairment of repair, and reduced ability to damage DNA after quenching of singlet oxygen

Melanins have been associated with the development of melanoma and its resistance to photodynamic therapy (PDT). Singlet molecular oxygen (102), which is produced by ultraviolet A solar radiation and the PDT system, is also involved. Here, we investigated the effects that these factors have on DNA damage and repair. Our results show that both types of melanin (eumelanin and pheomelanin) lead to DNA breakage in the absence of light irradiation and that eumelanin is more harmful than pheomelanin. Interestingly, melanins were found to bind to the minor grooves of DNA, guaranteeing close proximity to DNA and potentially causing the observed high levels of strand breaks. We also show that the interaction of melanins with DNA can impair the access of repair enzymes to lesions, contributing to the perpetuation of DNA damage. Moreover, we found that after melanins interact with 102, they exhibit a lower ability to induce DNA breakage; we propose that these effects are due to modifications of their structure. Together, our data highlight the different modes of action of the two types of melanin. Our results may have profound implications for cellular redox homeostasis, under conditions of induced melanin synthesis and irradiation with solar light. These results may also be applied to the development of protocols to sensitize melanoma cells to PDT. (c) 2012 Elsevier Inc. All rights reserved.

Poli (metil azoteto de glicidila) - GAP. I: síntese e caracterização

O poli (metil azoteto de glicidila) - GAP - é um material energético que pode ser utilizado como aglutinante (binder) e como plastificante energético em compostos explosivos e propulsores de foguetes. Neste trabalho, foi abordada a síntese do (GAP) através da conversão direta da epicloridrina (ECH) a GAP. Os reagentes utilizados foram azida de sódio, epicloridrina e vários álcoois extensores de cadeias, o etanodiol, o 1,4-butanodiol, o dietilenoglicol e o glicerol. Alguns parâmetros de operação foram avaliados, como o tempo de reação, a proporção entre os reagentes, dois tipos de solvente e a ordem de adição dos reagentes. A variável observada para a análise foi a massa molecular do GAP. Todos os materiais sintetizados também foram caracterizados por análises de FTIR, UV, RMN, DSC, análise elementar e TGA. Uma maior massa molecular, maior rendimento e uma melhor conversão do grupo azida a GAP foram obtidos com a adição de epicloridrina sobre a azida de sódio e usando DMF como solvente.

Poli (metil azoteto de glicidila) - GAP. II: mecanismo de reação

O poli (metil azoteto de glicidila) - GAP - é um material energético que pode ser utilizado como aglutinante (binder) e como plastificante energético em compostos explosivos e propulsores de foguetes. O GAP de baixo peso molecular pode ser obtido pela conversão direta da epicloridrina (ECH) a GAP. Neste trabalho, é proposto um possível mecanismo para esta conversão direta, fundamentado em análises de infravermelho de espécies intermediárias.

Rice husk derived waste materials as partial cement replacement in lightweight concrete

In this study rice husk ash (RHA) and broiler bed ash from rice husk (BBA), two agricultural waste materials, have been assessed for use as partial cement replacement materials for application in lightweight concrete. Physical and chemical characteristics of RHA and BBA were first analyzed. Three similar types of lightweight concrete were produced, a control type in which the binder was just CEMI cement (CTL) and two other types with 10% cement replacement with, respectively, RHA and BBA. All types of similar lightweight concrete were prepared to present the same workability by adjusting the amount of superplasticizer. Properties of concrete investigated were compressive and flexural strength at different ages, absorption by capillarity, resistivity and resistance to chloride ion penetration (CTH method) and accelerated carbonation. Test results obtained for 10% cement replacement level in lightweight concrete indicate that although the addition of BBA conducted to lower performance in terms of the degradation indicative tests, RHA led to the enhancement of mechanical properties, especially early strength and also fast ageing related results, further contributing to sustainable construction with energy saver lightweight concrete.