Titrimetric monitoring of a completely autotrophic nitrogen removal process.

Fully autotrophic nitrogen removal processes, such as the combined SHARON-Anammox process, help to improve the sustainability of wastewater treatment. Successful operation of such a completely autotrophic system is, among others, based on the strict control of the SHARON reactor in order to produce an Anammox-suited influent with a 1:1 ammonium:nitrite ratio. The high quality and high frequency measurements provided by a titrimetric set-up measuring the total ammonium (TAN) and total nitrite (TNO2) concentrations facilitate this control considerably. In this study, the use of a titrimetric set-up for monitoring the combined SHARON-Anammox process is investigated. The technique that interprets on-line collected titration curves was applied to a lab-scale system. Comparison with classic colorimetric results gave statistically indistinguishable results for TAN and TNO2 concentrations in the SHARON reactor. In the Anammox reactor, only TAN could be determined by the investigated method due to the very low TNO2 concentrations. Phosphate, a potential inhibitor of the Anammox process, is available as an additional measurement in the effluent of the SHARON reactor. Three measurements are thus combined in one single instrument. The proposed measuring technique holds different advantages over the other TAN and TNO2 measurement techniques such as on-site availability, easy automation, the absence of the need for high dilutions and cost reduction.     

Superfluid density and critical current of3He in confined geometries

Superfluid³He in severely confined geometries is studied in the Ginzburg-Landau limit. Both A and B phases are analyzed in narrow slabs and in small cylinders. Physically measurable quantities include the superfluid density and the critical current, which are significantly suppressed by the boundaries. Related alterations in the phase diagram are also considered. For small lateral dimensions, the A phase can be favored even well below the polycritical pressure.     

Characterization of glass-ceramic corrosion and durability

The chemical durability of some selected glass-ceramic materials based on the Li₂O- (MnO, CaO)MgO---Al₂O₃---SiO₂ glass composition, has been determined by HCl, using the powder test.

The leachability of the glass-ceramic was gradually increased by replacing MgO with MnO, while it was decreased by addition of MnO instead of CaO. Calcium oxide had a retarding effect on the durability of the material when it was added instead of MgO and/or MnO. However, on the addition of Al₂O₃ in replacing Li₂O, the durability of the material was markedly improved. The leaching data were found to be dependent mainly on the proportion of the glass oxide constituents i.e. MgO/MnO, CaO/MnO and Li₂O/Al₂O₃ ratios present in the glasses.

The results were correlated to different views concerning the effect of various ions on the rate of interdiffusion between the crystalline-glass materials and leaching solution, the type, and proportions of the crystalline phases developed in glass-ceramics and residual glass phase.     

Cottonseed colour fixed pigments. Part II. Role of hexane isomers on oil quality

The nature of disturbed thinking is explained from two different psychological perspectives and six major types of thought disorder are presented, classified, and discussed. The overlap between these different types of thought disturbance and some possible functions of disturbed thinking are outlined. A heuristic model for detecting thought disorder is presented; and, in addition, some complex conceptual and research issues involved with investigating and systematizing knowledge about disturbed thinking are explained.     

Solid solution phases from thermally crystallized Li2O-MgO-Al2O3-SiO2 glasses

Phase transformations have been studied in glasses related in composition to Li₂O-MgO-SiO₂ (930° C) eutectic glass modified by $\text{Al}{}_2\text{O}{}_3\text{Li}{}_2\text{O}$ replacement on a cation per cation basis. Crystallization processes and changes in the solid solutions of the mineral phases developed during the controlled heating of the glasses have been followed using X-ray and microscopic techniques.Solid solutions of lithia aluminosilicate phases (B-eucryptite and/or B-spodumene s.s.) are the essential minerals that crystallize in glasses through most of the heat treatment applied. Lithium metasilicate, disilicate, clinoenstatite and cordierite are also encountered.B-eucryptite s.s. is formed in early stage of crystallization of the glass which transforms into B-spodumene s.s. at higher temperature (800° C). However, in some cases, it persists at temperatures as high as 1000° C.Metastable B-eucryptite-B-quartz s.s. can accomodate considerable amounts of Mg²⁺ and Al³⁺ ions in its lattice especially at lower temperature. At higher temperature for long duration, a redistribution of the elements takes place, and the cordierite phase then developed.     

Novel design for accurate alignment of high voltage electrodes assembly

A design is described which enables the accurate alignment of high voltage plane parallel electrodes used in an ultra-high vacuum assembly. The main features of this design are that it effectively overcomes the eccentricities which are present in both the glass-to-metal graded seal used in the housing envelope and in the linear motion drives employed to vary the gap separation between the electrodes, as well as being relatively simple to fabricate. The present design has been successfully tested in two large chambers at applied voltages of up to 100 kV and at a background pressure of better than 10^?9 torr.     

On the formation of Taylor bubbles in small tubes

The formation of Taylor bubbles and resulting bubble lengths were studied in a ID vertical tube for air-water and air-octane systems. In the co-flow tube/nozzle arrangement two nozzle sizes were used as gas inlets. Superficial velocities varied between 0.001- for the liquid and 0.002- for the gas. Three different mechanisms of initial bubble formation were observed. Of the three mechanisms, mechanism 3 is periodic (with period consisting of a bubble and a liquid slug), reproducible and can be simply modelled. After initial bubble formation further modifications may occur in the formed bubble size by coalescence or pairing. Bubble pairing is encouraged by smaller nozzles and liquid flow rates, while coalescence is observed only for cases where non-Taylor bubbles form initially.Two simple models have been proposed, the first predicts the size of the Taylor bubbles formed by mechanism 3 while the second attempts to predict the condition for bubble pairing to occur. Reasonable agreement with experimental results validates the predictions of the first model for a strong dependence of the volume of Taylor bubbles formed on the gas and liquid flow rates, a moderate dependence on nozzle diameter and a weak dependence (if at all) on the surface tension of the liquid used. Mismatch with the experimental results is caused (at least in part) by the experimental setup where there was no perfect axial alignment of the gas inlet. The experiments also suffered from problems at the outlet at low flow rates where smooth bubble disengagement could not be ensured for long Taylor bubbles. The second model for pairing predicts its occurrence for concentric tube/nozzle arrangements as a function of flow rates and channel diameters. The model over-predicted the range of liquid flow rates at which pairing was observed experimentally, but it captured the form of the boundary between different bubble volume modification mechanisms when represented on superficial velocity graphs.     

Methodology for Efficient Substrate Noise Analysis in Large-Scale Mixed-Signal Circuits

A methodology is proposed to efficiently analyze substrate noise coupled to a sensitive block due to an aggressor digital block in large-scale mixed-signal circuits. The methodology is based on identifying voltage domains on the substrate by exploiting the small spatial voltage differences on the ground distribution network of the aggressor circuit. Specifically, similarly biased regions on the substrate short-circuited by the ground network are determined, and each of these regions is represented by a single equivalent input port to the substrate. The remaining ports within that domain are ignored to reduce the computational complexity of the extraction process. An algorithm with linear time complexity is proposed to merge those substrate contacts exhibiting a voltage difference smaller than a specified value, identifying a voltage domain. An equivalent contact is placed at the geometric mean of the merged contacts, ignoring all of the remaining ports such as the source/drain junctions of the devices. The ground network impedance is updated for each merged contact based on the proposed algorithm to maintain sufficient accuracy of the noise voltage. The substrate with reduced input ports is extracted using an existing extraction tool to analyze the noise at the sense node. As compared to the full extraction of an aggressor circuit, the methodology achieves a reduction of more than four orders of magnitude in the number of extracted substrate resistors with a peak-to-peak error of 24%.     

Optical and electrical properties of electrochemically deposited polyaniline-CeO2 hybrid nanocomposite film

This paper reports the optical and electrical properties of electrochemically deposited polyaniline (PANI)-cerium oxide (CeO2) hybrid nano-composite film onto indium-tin-oxide (ITO) glass substrate. UV–visible spectroscopy and I-V characteristic were performed to study the optical and electrical parameters of the electrochemically deposited film. The film exhibited a strong absorption below 400 nm (3.10 eV) with a well defined absorbance peak at around 285nm (4.35 eV). The estimated band gap of the CeO2 sample was 3.44 eV and this value is higher than bulk CeO2 powder (Eg = 3.19 eV) due to quantum confinement effect.     

Characteristics of heat transfer of impingement system with swap swirl generator

This article presents the computational fluid dynamic simulation of the heat transfer characteristics induced by a swap swirl air‐jet generator on the impingement surface. The study was carried out for conventional and swap twist tape inserts of twisted ratio y = 2.93 with various swap angles (α = 30°, 60°, 90°) at a constant distance of nozzle diameter impingement plate (L = 2D). The results show that the Nusselt number of the swirl impingement air‐jet depends on the twisted tape swap angles and airflow rate. The results also showed that the swap angle of 90° gave notable uniform local heat transfer distribution compared with the typical twist tape and other swap twist tapes (α = 30°, 60°). In addition, the predicted results of the local heat transfer coefficient help explain the local turbulence intensity and generation to assist the industrial applications of swirl impingement air‐cooling jet.