Experimental Investigation on Engineering Properties of Concrete Incorporating Reclaimed Asphalt Pavement and Rice Husk Ash

Waste generation from agricultural and construction industries is growing at an upsetting rate that causes a heavy burden on landfill facilities. On the other hand, the construction industry is exhausting natural resources thereby posing environmental problems. This study investigates the potential use of agro-industrial waste such as rice husk ash (RHA) and construction waste like reclaimed asphalt pavement (RAP) as promising construction materials. The durability and physical and mechanical properties of concrete were assessed by partially replacing cement and virgin aggregates with RHA and RAP, up to 20% and 50%, respectively. A total of 22 mixes were studied, twelve of which were devoted to studying the collective effects of RHA and RAP on the engineering properties of concrete. Based on experimental results, RHA and RAP decreased slump, compacting factor, density, water absorption and sorptivity. RHA increased compressive and tensile splitting strength, whereas RAP decreased compressive and tensile splitting strength. Comparable strength and favorable sorptivity values were obtained when 15% RHA was combined with up to 20% RAP in the concrete mix. Thus, utilizing RHA and RAP as concrete ingredients can contribute to solid waste management, engineering and economic benefits

Successful treatment of human visceral leishmaniasis restores antigen-specific IFN-γ, but not IL-10 production

One of the key immunological characteristics of active visceral leishmaniasis (VL) is a profound immunosuppression and impaired production of Interferon-γ (IFN-γ). However, recent studies from Bihar in India showed using a whole blood assay, that whole blood cells have maintained the capacity to produce IFN-γ. Here we tested the hypothesis that a population of low-density granulocytes (LDG) might contribute to T cell responses hyporesponsiveness via the release of arginase. Our results show that this population is affected by the anticoagulant used to collect blood: the frequency of LDGs is significantly lower when the blood is collected with heparin as compared to EDTA; however, the anticoagulant does not impact on the levels of arginase released. Next, we assessed the capacity of whole blood cells from patients with active VL to produce IFN-γ and IL-10 in response to antigen-specific and polyclonal activation. Our results show that whole blood cells produce low or levels below detection limit of IFN-γ and IL-10, however, after successful treatment of VL patients, these cells gradually regain their capacity to produce IFN-γ, but not IL-10, in response to activation. These results suggest that in contrast to VL patients from Bihar, India, whole blood cells from VL patients from Gondar, Ethiopia, have lost their ability to produce IFN-γ during active VL and that active disease is not associated with sustained levels of IL-10 production following stimulation

Comparison of complete blood count.

<p>Comparison of complete blood count.</p

Intestinal parasite distribution amongst VL patients.

<p>Intestinal parasite distribution amongst VL patients.</p

Frequency of LDGs.

<p>Frequency of LDGs.</p

IFN-γ levels in plasma from activated whole blood cells.

<p>Blood from non-endemic healthy controls (n = 10) was collected with heparin and EDTA and was activated at 37°C with PHA or PBS (nil = unstimulated). 24 hours later, the plasma was collected and the levels of IFN-γ were measured by ELISA as described in materials and methods and in exactly the same conditions and in the same laboratory as the VL patients. The value obtained for the unstimulated cells (nil) was subtracted from the values obtained for PHA stimulations. Each symbol represents the value for one individual, the straight lines represent the median, and statistical differences were determined using a Mann-Whitney test. The dotted line represents the detection limit.</p

Clinical data.

<p>Clinical data.</p

Frequency of LDGs in blood collected with EDTA and heparin.

<p>Blood from VL patients (n = 23) and non-endemic healthy controls (n = 10) was collected with heparin and EDTA, PBMCs were isolated by Ficoll gradient and the frequencies of LDGS (= CD15+ arginase+ cells[<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004468#pntd.0004468.ref012" target="_blank">12</a>]) were determined by flow cytometry. Each symbol represents the value for one individual, the straight lines represent the median, and statistical differences were determined using a Mann-Whitney test. A) VL patients, B) controls.</p

Arginase Activity in plasma from whole blood assay.

<p>Arginase Activity in plasma from whole blood assay.</p

The plasma from VL patients without intestinal parasite co-infections (IP-) and in VL patients co-infected with intestinal parasites (IP+) was tested by ELISA (CRP, IL-6, IL-8, myeloperoxidase and elastase) or enzymatic activity (arginase) as described in Materials and Methods.

<p>Statistical significance was established using a Mann-Whitney test, ns = not significant (<i>p</i><0.05).</p