Occurrence of Selected Metals in Wastewater Effluent and Surface Water in Ireland

Metals occur naturally in the environment and as constituents of the Earth’s crust. They have many uses, and metals such as iron, copper, and zinc are widely used in industries. Elevated levels of metals in the environment also occur as a result of human activities (municipal, residential, and traffic–related activities). A list of 15 metals chosen for this study included priority substances and those listed in the European Union Water Framework Directive 2000/60/EC. The concentrations of heavy metals in the environment are affected by several factors that must be taken into account when monitoring heavy metals released into the environment through wastewater treatment plants (WWPTs). This work examines the concentrations of metals found in WWPTs and the effects of treatment type on dissolved metal concentrations. Effluent samples were collected from the outflow of nine WWPTs in Dublin and Cork, Ireland from July 2009 to June 2011. All samples were found to contain priority metals that exceeded environmental quality standards in several cases. We present the frequency of occurrence and concentrations of metals in effluents of studied WWPTs and discuss relationships between the occurrence of heavy metals, the influence of factors such as industrial inputs, levels of treatment at WWPTs, and percentage urban area in an agglomeration. The results of this study are an indication that WWPTs may be contributing to the high levels of heavy metals found at discharge points back into river systems.     

A non-destructive internal nuclear forensic investigation at Argonne: discovery of a Pu planchet from 1948

A plutonium alpha standard dating from 1948 was discovered at Argonne National Laboratory and characterized using a number of non-destructive analytical techniques. The principle radioactive isotope was found to be ²³⁹Pu and unique ring structures were found across the surface of the deposition area. Due to chronological constraints on possible sources and its high isotopic purity, the plutonium in the sample was likely produced by the Oak Ridge National Lab X-10 Reactor. It is proposed that the rings are resultant through a combination of polishing and electrodeposition, though the hypothesis fails to address a few key features of the ring structures.

     

Binding of carboxylate and trimethylammonium salts to octa-acid and TEMOA deep-cavity cavitands

In participation of the fifth statistical assessment of modeling of proteins and ligands (SAMPL5), the strength of association of six guests (3–8) to two hosts (1 and 2) were measured by ¹H NMR and ITC. Each host possessed a unique and well-defined binding pocket, whilst the wide array of amphiphilic guests possessed binding moieties that included: a terminal alkyne, nitro-arene, alkyl halide and cyano-arene groups. Solubilizing head groups for the guests included both positively charged trimethylammonium and negatively charged carboxylate functionality. Measured association constants (K _a ) covered five orders of magnitude, ranging from 56 M^?1 for guest 6 binding with host 2 up to 7.43 × 10⁶ M^?1 for guest 6 binding to host 1.     

Well-posedness of Bayesian inverse problems in quasi-Banach spaces with stable priors

The Bayesian perspective on inverse problems has attracted much mathematical attention in recent years. Particular attention has been paid to Bayesian inverse problems (BIPs) in which the parameter to be inferred lies in an infinite-dimensional space, a typical example being a scalar or tensor field coupled to some observed data via an ODE or PDE. This article gives an introduction to the framework of well-posed BIPs in infinite-dimensional parameter spaces, as advocated by Stuart (Acta Numer. 19:451–559, 2010) and others. This framework has the advantage of ensuring uniformly well-posed inference problems independently of the finite-dimensional discretisation used for numerical solution. Recently, this framework has been extended to the case of a heavy-tailed prior measure in the family of stable distributions, such as an infinite-dimensional Cauchy distribution, for which polynomial moments are infinite or undefined. It is shown that analogues of the Karhunen–Loève expansion for square-integrable random variables can be used to sample such measures on quasi-Banach spaces. Furthermore, under weaker regularity assumptions than those used to date, the Bayesian posterior measure is shown to depend Lipschitz continuously in the Hellinger and total variation metrics upon perturbations of the misfit function and observed data. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Medium-high resolution electrochemical genotyping of HLA-DQ2/DQ8 for detection of predisposition to coeliac disease

Coeliac disease is a small intestinal disorder, induced by ingestion of gluten in genetically predisposed individuals. Coeliac disease has been strongly linked to human leukocyte antigens (HLA) located on chromosome 6, with almost 100 % of coeliac disease sufferers carrying either a HLA-DQ2 or HLA-DQ8 heterodimer, with the majority carrying HLA-DQ2 encoded by the DQA1*05:01/05:05, DQB1*02:01/02:02 alleles, whereas the remaining carry the HLA-DQ8 encoded by the DQA1*03:01, DQB1*03:02 alleles. In this work, we present the development of a multiplex electrochemical genosensor array of 36 electrodes, housed within a dedicated microfluidic platform and using a total of 10 sequence-specific probes for rapid medium-high resolution HLA-DQ2/DQ8 genotyping. An evaluation of the selectivity of the designed probes was carried out with the target sequences and 44 potentially interfering alleles, including single base mismatch differentiations; good selectivity was demonstrated. The performance of the electrochemical genosensor array was validated, analyzing real human samples for the presence of HLA-DQ2/DQ8 alleles, and compared with those obtained using laboratory-based HLA typing, and an excellent correlation was obtained.

Shear properties and a stress analysis obtained from vinyl-ester losipescu specimens

The use of losipescu specimens for the determination of the shear properties of a vinyl-ester resin was investigated. The antisymmetric four-point bend and the Adams and Walrath fixtures were studied for their suitability in loading these specimens. Photoelastic and strain-gage data in addition to published finite-element results show that the latter fixture distorts the stress field in the gage section. The antisymmetric four-point bend fixture is found to give the purest shear-stress field in the gage section and to yield the most reliable shear-modulus values. A refined photoelastic analysis shows that the shear-stress distribution between the notch roots is essentially uniform with a relative maximum or minimum at the centroid depending on the depths of the notches. Also, stress risers of up to 30 percent are observed near the notch roots. Except at the roots, finite-element predictions are presented which are in excellent agreement with photoelastic data. The failure mode of this vinyl-ester resin is tensile and the corresponding tensile stress calculated from the average shear stress in the gage section of the losipescu specimen is in excellent agreement with failure data acquired in tension.     

Visualization of jet mixing in a fluidic oscillator

The fluidic oscillator is a device that generates an oscillating jet when supplied with fluid at pressure. The oscillator has no moving parts — the creation of the unsteady jet is based solely on fluid-dynamic interactions. Fluidic oscillators can operate at frequencies ranging up to 20 kHz, and are useful for flow control applications. The fluidic oscillator evaluated in the current study is comprised of two fluid jets that interact in an internal mixing chamber, producing the oscillating jet at the exit. Both porous pressure-sensitive paint (PSP) and dye-colored water flow are used to visualize the internal and external fluid dynamics of the oscillator. Porous PSP formulations have been shown to have frequency responses on the order of 100 kHz, which is more than adequate for visualizing the fluidic oscillations. In order to provide high-contrast PSP data in these tests, one of the internal jets of the fluidic oscillator is supplied with oxygen, and the other with nitrogen. Results indicate that two counter-rotating vortices within the mixing chamber drive the oscillations. It is also shown that the fluidic oscillator possesses excellent mixing characteristics.     

Corrugated waveguide band edge filters for CMB experiments in the far infrared

Millimetre wave corrugated waveguide-horn structures are used as both single-moded and multi-moded bolometer feeds in a number of cosmic microwave background (CMB) experiments (e.g. PLANCK, Archeops, QUaD). Such horns tend to be employed over a relatively wide bandwidth and for single-moded horns the waveguide acts as the high pass filter. In this paper we report on our investigation on how the waveguide details determine the exact location of the low frequency band edge of such corrugated horns. A sharp step-like band edge, below which there is negligible propagation, is ideally required. Furthermore any leakage below the expected cut-off, possible in corrugated guides, could lead to non-idealised cross-polar effects. Typically deeper corrugations are required in the waveguide filter than at the horn aperture for wide bandwidth operation, thus necessitating a transition section over which the corrugation depth smoothly varies. An electromagnetic mode matching technique and a surface impedance hybrid mode model are used to compute the horn transmission characteristics. We have also undertaken laboratory measurements of the band edge of prototype corrugated horns in order to test the models.