414 research outputs found
Multivariate analysis of the effects of age, particle size and landfill depth on heavy metals pollution content of closed and active landfill precursors
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Multivariate analysis of a heavy metal pollution survey of closed and active landfill precursors was carried out in order to compare environmental risk levels in relation to age, particle size and depth of the precursors. Landfill precursors (77) were collected and analyzed for 15 USEPA toxic heavy metals using ICP-MS. Heavy metals concentrations in closed landfill precursors were significantly higher than those in the active landfill for 11 of 15 heavy metals investigated (closed landfill order: Fe > Al > Mn > Cu > Pb > Ba> Co > Cr > Ni > Cd > As > Se > Ti). Cluster analysis and correlation studies indicated the distribution of the metals was more influenced by landfill precursor size than by depth of the sample. Principal component analysis (PCA) showed that 10 of 15 of heavy metals of both landfill precursors were from similar anthropogenic sources. Heavy metals pollution indices (Igeo > 5, EF > 40 and CF > 7) of both active and closed landfill precursors exceeded limits in the order of Zn > Cd > Pb > Cu > Ag, indicating a major potential health risk influenced by age and particle size of precursor. Zn, Cd, Cu and Pb of both landfill precursors exceeded the USEPA set standard for assessment of human health risk for each of the metals (1Ă10 -4 to 1Ă 10-3). This study highlights the need for the integration of a clean-up process for precursors from both types of landfill to reduce possible environmental pollution during a reuse process
Conversion of solid waste to activated carbon to improve landfill sustainability
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Landfillsâ heterogeneous composites waste were evaluated as precursors for generation of activated carbon (AC). A single step chemical activation process was applied involving irradiation with microwave energy and impregnation with KOH. The average percentage yield of AC from active landfill precursor was higher than that from closed landfill for all depths sampled. Increase in impregnation ratio and irradiation power decreased the average percentage yield for both landfill precursors (Active: 38.1 to 33.1%) (Closed 42.1: to 33.3%). The optimum pH range for adsorption of methylene blue was pH 6-7, while adsorption increased with increase in temperature over the range 30 to 50oC. Carbonyl and hydroxyl groups were the major functional groups on the surface of AC. The properties of the AC are potentially suitable for the removal of cationic dyes and pollutants. AC generated from the landfill composite were comparable to that from some other biomass being managed through AC generation. This is the first report to demonstrate the possible reuse of landfill composite as AC. The reuse option of landfill composite could provide a means of sustainable management of landfilled municipal waste
Effect of Polymerization Conditions on Thermal and Mechanical Properties of Ethylene/1-Butene Copolymer Made with Ziegler-Natta Catalysts
The effect of polymerization conditions on thermal and mechanical properties of ethylene/1-butene copolymers synthesized through titanium-magnesium-supported Ziegler-Natta catalysts was studied. The increase in hydrogen pressure leads to a decrease in molecular weight (MW), storage modulus, and melting temperature. However, it yields an increase in molecular weight distribution (MWD), tan , % crystallinity, tensile modulus, yield stress, and strain at break. The effects of ethylene pressure and polymerization temperature on the copolymer MW, MWD and thermal and mechanical properties have been investigated. However, the impacts of ethylene pressure and polymerization temperature on copolymer modulus, tensile strength, % crystallinity, crystallization peak temperature, yield stress, strain at break, and yield strain are marginal. The hydrogen pressure plays a major role in controlling the copolymer properties because it acts as an efficient chain transfer agent during polymerization reaction. The MW is the key parameter that influences flow activation energy. However, the other mechanical, dynamic mechanical, and thermal properties not only depend on MW but are also influenced by other parameters
Pre-seismic, co-seismic and post-seismic displacements associated with the Bhuj 2001 earthquake derived from recent and historic geodetic data
The 26th January 2001 Bhuj earthquake occurred in the Kachchh Rift Basin which has a long history of major earthquakes. Great Triangulation Survey points (GTS) were first installed in the area in 1856-60 and some of these were measured using Global Positioning System (GPS) in the months of February and July 2001. Despite uncertainties associated with repairs and possible reconstruction of points in the past century, the re-measurements reveal pre-seismic, co-seismic and post-seismic deformation related to Bhuj earthquake. More than 25 M-strain contraction north of the epicenter appears to have occurred in the past 140 years corresponding to a linear convergence rate of approximately 10 mm/yr across the Rann of Kachchh. Motion of a single point at Jamnagar 150 km south of the epicenter in the 4 years prior to the earthquake, and GTS-GPS displacements in Kathiawar suggests that pre-seismic strain south of the epicenter was small and differs insignificantly from that measured elsewhere in India. Of the 20 points measured within 150 km of the epicenter, 12 were made at existing GTS points which revealed epicentral displacements of up to 1 m, and strain changes exceeding 30 M-strain. Observed displacements are consistent with reverse co-seismic slip. Re-measurements in July 2001 of one GTS point (Hathria) and eight new points established in February reveal post-seismic deformation consistent with continued slip on the Bhuj rupture zone
Harmonising the training of students within the EU to implement intervention programmes to protect the public in the aftermath of a HazMat incident
Lower bounds on the dilation of plane spanners
(I) We exhibit a set of 23 points in the plane that has dilation at least
, improving the previously best lower bound of for the
worst-case dilation of plane spanners.
(II) For every integer , there exists an -element point set
such that the degree 3 dilation of denoted by in the domain of plane geometric spanners. In the
same domain, we show that for every integer , there exists a an
-element point set such that the degree 4 dilation of denoted by
The
previous best lower bound of holds for any degree.
(III) For every integer , there exists an -element point set
such that the stretch factor of the greedy triangulation of is at least
.Comment: Revised definitions in the introduction; 23 pages, 15 figures; 2
table
Human biomonitoring research at De Montfort University: school and university participants' recruitment experience
Involving teachers in scientific research can increase schoolchildrenâs interest in studying science from an early stage which is critical to increase the numbers of high-school students studying scientific subjects. This will impact on the number of students enrolled in university science degrees to satisfy many basic human needs. A group of academics at De Montfort University (DMU, UK) have involved the Ravenhurst Primary School (RPS) in biomedical research, specifically a human biomonitoring (HBM) study involving schoolchildren (aged 6-9 years) and university students (aged 18-22 years) in Leicester (UK) to determine their nutritional status and exposure to metals. We have adopted a school-based approach to recruit participants from both educational arenas following the recommendations for executing HBM studies in Europe [1] with some modifications.
Permission from the school authorities was requested after gaining ethical approval from the DMU Research Ethics Committee (Ref. 1674). Parental/student consent was obtained by invitation and appointment letter, with the project details and ethical and data protection aspects written in simple language. Appropriately developed flyers, posters and information leaflets for each audience were also used to enhance the recruitment processes. Scheduling and facilitating flexible face-to-face appointments was critical for collecting the human samples needed for the project (urine and scalp hair) as well as comprehensive details about participantsâ diet and anthropometric measurements. The involvement of teachers and lecturers in conjunction with a registered general nurse (school nursing) was of paramount importance for achieving these goals, as they were encouraging participation throughout the process. During the appointments, parents and participants were debriefed in more detail about the project and the relevance of performing HBM to improve health in the community.
The school-based approach achieved the following results: a) the recruitment of a relevant number of participants (12 schoolchildren and 111 university students); b) the provision of a satisfying educational experience for parents, teachers/academics and participants in both educational arenas; c) the involvement of school-children in scientific research; d) the acquisition of awareness of the impact of environmental contamination by metals on human health; e) informing participants about their diets and body composition (e.g. percentage of body fat) promoting the necessity of adopting a healthy diet and lifestyle.
In conclusion, the project was successful in involving School teachers, University lecturers, schoolchildren, University students and community health workers in a research project. It provided an opportunity for educational development, promote staff motivation and studentsâ interest and involvement in scientific research. Teachers updated their biomedical knowledge and skills by participating in this research and learnt new methods to engage schoolchildren (by promoting healthy lifestyles, protect the environment, etc.). This could help increase studentsâ interest in studying science subjects at University and motivate them to embark on a future scientific career. Finally, the UK education system should do more to engage schools and teachers in performing scientific research and thereby make the scientific curriculum more practical that will facilitate studentsâ learning and engagement
Recommended from our members
Dairy consumption and cardiometabolic diseases: systematic review and updated meta-analyses of prospective cohort studies
Purpose of Review Dairy products contain both beneficial and harmful nutrients in relation to cardiometabolic diseases. Here, we
provide the latest scientific evidence regarding the relationship between dairy products and cardiometabolic diseases by
reviewing the literature and updating meta-analyses of observational studies.
Recent Findings We updated our previous meta-analyses of cohort studies on type 2 diabetes, coronary heart disease (CHD), and
stroke with nine studies and confirmed previous results. Total dairy and low-fat dairy (per 200 g/d) were inversely associated with
a 3â4% lower risk of diabetes. Yogurt was non-linearly inversely associatedwith diabetes (RR = 0.86, 95%CI: 0.83â0.90 at 80 g/
d). Total dairy and milk were not associated with CHD (RR~1.0). An increment of 200 g of daily milk intake was associated with
an 8% lower risk of stroke.
Summary The latest scientific evidence confirmed neutral or beneficial associations between dairy products and risk of cardiometabolic
diseases
Automated Reconstruction of Neuronal Morphology Based on Local Geometrical and Global Structural Models
Digital reconstruction of neurons from microscope images is an important and challenging problem in neuroscience. In this paper, we propose a model-based method to tackle this problem. We first formulate a model structure, then develop an algorithm for computing it by carefully taking into account morphological characteristics of neurons, as well as the image properties under typical imaging protocols. The method has been tested on the data sets used in the DIADEM competition and produced promising results for four out of the five data sets
Global sourcing of low-inorganic arsenic rice grain
Arsenic in rice grain is dominated by two species: the carcinogen inorganic arsenic (the sum of arsenate and arsenite) and dimethylarsinic acid (DMA). Rice is the dominant source of inorganic arsenic into the human diet. As such, there is a need to identify sources of low-inorganic arsenic rice globally. Here we surveyed polished (white) rice across representative regions of rice production globally for arsenic speciation. In total 1180 samples were analysed from 29 distinct sampling zones, across 6 continents. For inorganic arsenic the global x ~
x~
was 66 ÎŒg/kg, and for DMA this figure was 21 ÎŒg/kg. DMA was more variable, ranging from <â2 to 690 ÎŒg/kg, while inorganic arsenic ranged fromâ<â2 to 399 ÎŒg/kg. It was found that inorganic arsenic dominated when grain sum of species was <â100 ÎŒg/kg, with DMA dominating at higher concentrations. There was considerable regional variance in grain arsenic speciation, particularly in DMA where temperate production regions had higher concentrations. Inorganic arsenic concentrations were relatively consistent across temperate, subtropical and northern hemisphere tropical regions. It was only in southern hemisphere tropical regions, in the eastern hemisphere that low-grain inorganic arsenic is found, namely East Africa (x ~
x~
â<â10 ÎŒg/kg) and the Southern Indonesian islands (x ~
x~
â<â20 ÎŒg/kg). Southern hemisphere South American rice was universally high in inorganic arsenic, the reason for which needs further exploration
- âŠ