Bauxite residue, the by-product produced in the alumina industry, is a potential low-cost adsorbent in the removal of phosphorus (P) from aqueous solution, due to its high composition of residual ...iron oxides such as hematite. Several studies have investigated the performance of bauxite residue in removing P; however, the majority have involved the use of laboratory “batch” tests, which may not accurately estimate its actual performance in filter systems. This study investigated the use of rapid, small-scale column tests to predict the dissolved reactive phosphorus (DRP) removal capacity of bauxite residue when treating two agricultural waters of low (forest run-off) and high (dairy soiled water) phosphorus content. Bauxite residue was successful in the removal of DRP from both waters, but was more efficient in treating the forest run-off. The estimated service time of the column media, based on the largest column studied, was 1.08 min g−1 media for the forest run-off and 0.28 min g−1 media for the dairy soiled water, before initial breakthrough time, which was taken to be when the column effluent reached approximately 5% of the influent concentration, occurred. Metal(loid) leaching from the bauxite residue, examined using ICP-OES, indicated that aluminium and iron were the dominant metals present in the treated effluent, both of which were above the EPA parametric values (0.2 mg L−1 for both Al and Fe) for drinking water.
•Bauxite residue was examined as an adsorbent for phosphorus using a column study.•The bauxite residue had a service time of 1.08 min g−1 media for the forest run-off.•The service time was 0.28 min g−1 media when treating dairy soiled water.•The bauxite residue was examined before and after the adsorption process.
We explored risk factors for myopia in 12- to 13-year-old children in Northern Ireland (NI).
Stratified random sampling was performed to obtain representation of schools and children. Cycloplegia was ...achieved using cyclopentolate hydrochloride 1%. Distance autorefraction was measured using the Shin-Nippon SRW-5000 device. Height and weight were measured. Parents and children completed a questionnaire, including questions on parental history of myopia, sociodemographic factors, childhood levels of near vision, and physical activity to identify potential risk factors for myopia. Myopia was defined as spherical equivalent ≤-0.50 diopters (D) in either eye.
Data from 661 white children aged 12- to 13-years showed that regular physical activity was associated with a lower estimated prevalence of myopia compared to sedentary lifestyles (odds ratio OR = 0.46 adjusted for age, sex, deprivation score, family size, school type, urbanicity; 95% confidence interval CI, 0.23-0.90; P for trend = 0.027). The odds of myopia were more than 2.5 times higher among children attending academically-selective schools (adjusted OR = 2.66; 95% CI, 1.48-4.78) compared to nonacademically-selective schools. There was no evidence of an effect of urban versus nonurban environment on the odds of myopia. Compared to children with no myopic parents, children with one or both parents being myopic were 2.91 times (95% CI, 1.54-5.52) and 7.79 times (95% CI, 2.93-20.67) more likely to have myopia, respectively.
In NI children, parental history of myopia and type of schooling are important determinants of myopia. The association between myopia and an environmental factor, such as physical activity levels, may provide insight into preventive strategies.
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Additive manufacturing (AM) is fundamentally different from traditional formative or subtractive manufacturing in that it is the closest to the ‘bottom up’ manufacturing where a ...structure can be built into its designed shape using a ‘layer-by-layer’ approach rather than casting or forming by technologies such as forging or machining. AM is versatile, flexible, highly customizable and, as such, can suite most sectors of industrial production. Materials to make these parts/objects can be of a widely varying type. These include metallic, ceramic and polymeric materials along with combinations in the form of composites, hybrid, or functionally graded materials (FGMs). The challenge remains, however, to transfer this ‘making’ shapes and structures into obtaining objects that are functional. A great deal of work is needed in AM in addressing the challenges related to its two key enabling technologies namely ‘materials’ and ‘metrology’ to achieve this functionality in a predictive and reproductive ways. The good news is that there is a significant interest in industry for taking up AM as one of the main production engineering route. Additive Manufacturing, in our opinion, is definitely at the cross-road from where this new, much-hyped but somewhat unproven manufacturing process must move towards a technology that can demonstrate the ability to produce real, innovative, complex and robust products.
We performed a prospective study of the changing profile of astigmatism in white school children in Northern Ireland.
Of the 399 6- to 7-year-old and 669 12- to 13-year-old participants in Phase 1 of ...the Northern Ireland Childhood Errors of Refraction (NICER) study, 302 (76%) of the younger and 436 (65%) of the older cohort were re-examined three years later (Phase 2). Stratified random cluster sampling was used. Following cycloplegia (cyclopentolate HCl 1%) refractive error was recorded by the Shin-Nippon-SRW-5000 autorefractor. Astigmatism is defined as ≥ 1.00 diopters cylinder (DC). Right eye data only are presented.
The prevalence of astigmatism was unchanged in both cohorts: younger cohort 17.1% (95% confidence intervals CIs, 13.3-21.6) were astigmatic at 9 to 10 years compared to 22.9% (95% CIs, 18.3-28.2) at 6 to 7 years; older cohort, 17.5% (95% CIs, 13.9-21.7) of participants were astigmatic at 15-16 years compared to 18.4% (95% CIs, 13.4-24.8) at age 12 to 13 years. Although prevalence remained unchanged, it was not necessarily the same children who had astigmatism at both phases. Some lost astigmatism (10.0%; CIs, 7.5-13.3 younger cohort and 17.4%; CIs, 13.5-22.2 older cohort); others became astigmatic (9.1%; CIs, 6.7-12.2 younger cohort and 11.6%; CIs, 8.4-15.8 older cohort).
This study presents novel data demonstrating that the astigmatic error of white children does not remain stable throughout childhood. Although prevalence of astigmatism is unchanged between ages 6 and 7 to 15 to 16 years; during this time period individual children are developing astigmatism while other children become nonastigmatic. It is difficult to predict from their refractive data who will demonstrate these changes, highlighting the importance of all children having regular eye examinations to ensure that their visual requirements are met.
To determine six-year spherical refractive error change among white children and young adults in the UK and evaluate differences in refractive profiles between contemporary Australian children and ...historical UK data.
Population-based prospective study.
The Northern Ireland Childhood Errors of Refraction (NICER) study Phase 1 examined 1068 children in two cohorts aged 6-7 years and 12-13 years. Prospective data for six-year follow-up (Phase 3) are available for 212 12-13 year olds and 226 18-20 year olds in each cohort respectively.
Cycloplegic refractive error was determined using binocular open-field autorefraction (Shin-Nippon NVision-K 5001, cyclopentolate 1%). Participants were defined by spherical equivalent refraction (SER) as myopic SER ≤-0.50D, emmetropic -0.50D<SER<+2.00 or hyperopic SER≥+2.00D.
Proportion and incidence of myopia.
The proportion of myopes significantly increased between 6-7 years (1.9%) and 12-13 years (14.6%) (p<0.001) but not between 12-13 and 18-20 years (16.4% to 18.6%, p = 0.51). The estimated annual incidence of myopia was 2.2% and 0.7% for the younger and older cohorts respectively. There were significantly more myopic children in the UK at age 12-13 years in the NICER study (16.4%) than reported in Australia (4.4%) (p<0.001). However by 17 years the proportion of myopia neared equivalence in the two populations (NICER 18.6%, Australia 17.7%, p = 0.75). The proportion of myopic children aged 12-13 years in the present study (2006-2008) was 16.4%, significantly greater than that reported for children aged 10-16 years in the 1960's (7.2%, p = 0.01). The proportion of hyperopes in the younger NICER cohort decreased significantly over the six year period (from 21.7% to 14.2%, p = 0.04). Hyperopes with SER ≥+3.50D in both NICER age cohorts demonstrated persistent hyperopia.
The incidence and proportion of myopia are relatively low in this contemporary white UK population in comparison to other worldwide studies. The proportion of myopes in the UK has more than doubled over the last 50 years in children aged between 10-16 years and children are becoming myopic at a younger age. Differences between the proportion of myopes in the UK and in Australia apparent at 12-13 years were eliminated by 17 years of age.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To investigate the utility of uncorrected visual acuity measures in screening for refractive error in white school children aged 6-7-years and 12-13-years.
The Northern Ireland Childhood Errors of ...Refraction (NICER) study used a stratified random cluster design to recruit children from schools in Northern Ireland. Detailed eye examinations included assessment of logMAR visual acuity and cycloplegic autorefraction. Spherical equivalent refractive data from the right eye were used to classify significant refractive error as myopia of at least 1DS, hyperopia as greater than +3.50DS and astigmatism as greater than 1.50DC, whether it occurred in isolation or in association with myopia or hyperopia.
Results are presented from 661 white 12-13-year-old and 392 white 6-7-year-old school-children. Using a cut-off of uncorrected visual acuity poorer than 0.20 logMAR to detect significant refractive error gave a sensitivity of 50% and specificity of 92% in 6-7-year-olds and 73% and 93% respectively in 12-13-year-olds. In 12-13-year-old children a cut-off of poorer than 0.20 logMAR had a sensitivity of 92% and a specificity of 91% in detecting myopia and a sensitivity of 41% and a specificity of 84% in detecting hyperopia.
Vision screening using logMAR acuity can reliably detect myopia, but not hyperopia or astigmatism in school-age children. Providers of vision screening programs should be cognisant that where detection of uncorrected hyperopic and/or astigmatic refractive error is an aspiration, current UK protocols will not effectively deliver.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Adsorption studies were carried out on a red mud modified sawdust biochar material to assess its capacity in the removal of vanadium (V) from aqueous solution. In this study, a number of parameters ...which can potentially influence V(V) adsorption were investigated including equilibrium V(V) solution concentration, contact time for effective V(V) removal, temperature of the adsorption process, solution pH and ionic strength. The uptake of V(V) was shown to be heavily influenced by solution pH with maximum uptake (16.45 mg g−1) achieved in the pH range of 3.5 - 5.5. The adsorption process was best described by the Langmuir model. The kinetics of the adsorption process indicated that V(V) uptake occurred within 60 min of contact and that pseudo-second order kinetics best described the kinetics of the overall adsorption process. There was a clear increase in V(V) uptake with increasing temperature (range 293–343 K) indicating an endothermic adsorption process and the level of uptake remained largely unchanged at solution salt concentrations of up to 0.1 M NaCl and competing cation concentrations of up to 2000 mg L-1 of sodium and 200 mg L-1 aluminium. The relatively weak interaction between V(V) and the modified biochar surface may indicate a possibility of recovery of the bound V(V) and subsequent regeneration of the adsorbent.
Bauxite residue, the byproduct of alumina production, may potentially be a valuable source of strategically important metals, e.g. Gallium. Ga is considered critical element for the EU. To ensure ...adequate supply of Ga for the future, secondary sources such as bauxite residue should be exploited with efficient extraction methods. Therefore, in this study, mineral acids (H
2
SO
4
, HCl, and HNO
3
) and an organic acid (H
2
C
2
O
4
—oxalic acid), were evaluated for their efficiencies to extract Ga from bauxite residue. Using H
2
C
2
O
4
, the highest Ga leaching efficiencies were achieved, compared to other acids. The achieved leaching experimental results were considered for the construction of a design of experiment (DOE) model to achieve optimal conditions for Ga extraction using H
2
C
2
O
4
. These values were validated by experiments which resulted in ~ 94% accuracy. In the second part of the study, using pure Ga solution, the adsorption of Ga onto zeolite HY was studied. The effects of adsorbent dosage, temperature, and contact time on the adsorption of Ga from solution by zeolite HY were studied. The obtained adsorption experimental results were used to construct a DOE model to achieve optimal conditions for Ga adsorption on to zeolite HY. The DOE-achieved optimal conditions were evaluated by experiments in pure Ga solution, which resulted in an efficiency of ~ 99.4 %. In the third stage, the bauxite residue was leached in H
2
C
2
O
4
under the optimal DOE conditions which resulted in 71% efficiency; thus the resulting bauxite residue solution was subjected to adsorption using zeolite HY under the optimal DOE conditions achieved. The Ga adsorption onto the zeolite was only 16% compared to the Ga adsorption of 99.4 % under the pure Ga solution, thus, representing the influences of the other leachates in the solution, which are minimizing the Ga adsorption onto the zeolite HY and providing an opportunity for future studies on the different mechanisms involved.
LCD screens are part of our daily life for entertainment, communications and networking. One of the key materials within an LCD screen is indium-Tin-Oxide (ITO). Although the ITO layer in LCDs is ...nano-meter thick, the volume of such screens produced is very large and thus accessing the required amounts of indium is important. Therefore recovering indium from discarded LCD screens is a potential opportunity to sustain future indium requirements. Efforts are being made by researchers to recover indium from LCD screens using conventional hydrometallurgical techniques where acids are used to leach indium. Very few studies reported non-conventional hydrometallurgical techniques such as use of sonication. In this study a comparison of conventional and non-conventional techniques is studied. Also the influence of the glass morphology on indium leaching was studied: as-leached LCD glass and ground LCD glass powder. It is found that, upon filtering, the ground LCD powder can concentrate indium in fine particle fraction and leave bulk of the glass ready for recycling. The sonication method was found to accelerate the indium leaching thus allowing for low volume acid usage. These studies also provided valuable results regarding the possibilities to vary acid concentration.
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