Feasibility of using electrodialysis with bipolar membranes to deacidify acid whey

A nonreagent method for the regulation of the pH of acid whey was investigated at a laboratory scale. Acid whey and concentrated acid whey were subjected to electrodialysis with bipolar membranes in order to raise the pH value to 6.5. Demineralised whey underwent identical processing. The deacidification rate as per tonne of a dry matter was similar for acid whey and concentrated acid whey treatment at 70% and 90% degrees of demineralisation. We estimated the energy consumption of electrodialysis. The preliminary demineralisation of whey significantly increased the energy efficiency of whey pH correction. Additionally, we observed substantial fouling on the diluate side of bipolar membranes after whey treatment.     

A transient mathematical model for maximum respiration activity and oxygen diffusion coefficient estimation in non-steady-state biofilms

A transient mathematical model was established in order to evaluate oxygen diffusivity in non-steady-state biofilms. A submerged fixed bed biofilm system with efficient medium recirculation was investigated for p-toluenesulphonic acid degradation by Comamonas testosteroni T-2 in a multi-species biofilm. Static mixer elements (Sulzer Chemtech Ltd, Switzerland) were used as a support matrix for biofilm formation. Biofilm respiration was estimated using the dynamic gassing-out oxygen uptake method. Based on the dissolved oxygen concentration profiles, the oxygen diffusion coefficient and the maximum respiration activity were calculated. The values of the dissolved oxygen diffusion coefficient varied with biolfilm development and values reported here (2×10⁻¹⁰–1.2×10⁻⁹ m² s⁻¹) are in good agreement with literature data. Calculated oxygen consumption rates fit well with values obtained in respirometry tests with washed out biofilms. The knowledge of diffusivity changes in biofilms is particularly important for removal capacity estimation and appropriate reactor design. © 1998 Society of Chemical Industry     

Phase diagrams of advanced magnesium alloys containing Al,Ca, Sn,Sr, and Mn

In this paper an overview of the most relevant phase diagrams is given comprising the unconventional alloying elements Sn, Ca, and Sr, in reasonable combinations with Al and Mn in Mg alloys as a basis for advanced applications. The focus is on magnesium-rich partial projections of the liquidus surface of five ternary systems, relevant to technological applications for lightweight materials. All phase diagrams are calculated from a coherent thermodynamic multicomponent database for magnesium alloys. These calculations are validated by key samples in the pertinent subsystems, including extensive ternary assessments and also quaternary work. Isothermal sections of magnesium-rich phase diagrams of alloys with constant aluminum and manganese content at 500°C and 550°C are given for the two five-component systems: Mg-Al-Mn-Ca-Sr and Mg-Al-Mn-Ca-Sn.     

Requirements quality control: a unifying framework

Literature tends to discuss software (and system) requirements quality control, which includes validation and verification, as a heterogeneous process using a great variety of relatively independent techniques. Also, process-oriented thinking prevails. In this paper, we attempt to promote the point that this important activity must be studied as a coherent entity. It cannot be seen as a rather mechanical process of checking documents either. Validation, especially, is more an issue of communicating requirements, as constructed by the analysts, back to the stakeholders whose goals those requirements are supposed to meet, and to all those other stakeholders, with whose goals those requirements may conflict. The main problem, therefore, is that of achieving a sufficient level of understanding of the stated requirements by a particular stakeholder, which may be hindered by, for example, lack of technical expertise. In this paper, we develop a unifying framework for requirements quality control. We reorganize the existing knowledge around the issue of communicating requirements to all the different stakeholders, instead of just focusing on some techniques and processes. We hope that this framework could clarify thinking in the area, and make future research a little more focused.     

Double-doped YFeO3 as new electrodes for protonic ceramic fuel cells

Mixed ionic-electronic conductors (MIECs) based on YFeO₃ are positioned as one of the promising cathode materials for intermediate-temperature solid oxide fuel cells (so-called protonic ceramic fuel cells or PCFCs) based on proton-conducting electrolytes. Simultaneous modification of both basic cationic sublattices of YFeO₃ by calcium and iron was used to tailor the functionality of the obtained Y_0.9Ca_0.1Fe_1–хСo_хO_3–δ (x = 0.2, 0.3, 0.4 and 0.5) compounds. Following the successful synthesis of these oxides, such functional characteristics as structural, thermal, transport properties and electrochemical activity were extensively studied taking the composition (i.e. cobalt concentration, x) into account. The complex analysis carried out on the obtained data shows that Co-doping results in improved electrical conductivity and electrochemical polarisation resistance with no adverse effects on their thermal expansion, even at the highest cobalt content (x = 0.5). The performance of a single SOFC with the selected Y_0.9Ca_0.1Fe_0.5Сo_0.5O_3–δ electrode confirms the prospects of Y_0.9Ca_0.1Fe_1–хСo_хO_3–δ phases as modernized MIECs having good thermal properties and acceptable electrochemical activity.     

Effect of dispersed CdSe/ZnS quantum dots on optical and electrical characteristics of nematic liquid crystal cells

We have studied the electrical and optical characteristics of cells filled with nematic liquid crystal (NLC) based on cyanobiphenyls with positive dielectric anisotropy, containing dispersed 3.5-nm-sized CdSe/ZnS composite semiconductor nanoparticles (quantum dots, QDs) with a concentration of 0.1–0.2 wt %. In addition to a decrease in the threshold voltage of the electrooptical splay effect, the doping with QDs leads also to a decrease in the phase delay of light and the effective dielectric permittivity of NLC cells. These characteristics are reduced by half during the storage of NLC cells containing about 0.2 wt % QDs, which is related to the self-organization of QDs.     

Embedded TLS 1.2 Implementation for Smart Metering & Smart Grid Applications

Digital networked communications are the key to all Internet-of-Things applications, especially to smart metering systems and the smart grid. In order to ensure a safe operation of systems and the privacy of users, the transport layer security (TLS) protocol, a mature and well standardized solution for secure communications, may be used. We implemented the TLS protocol in its latest version in a way suitable for embedded and resource-constrained systems. This paper outlines the challenges and opportunities of deploying TLS in smart metering and smart grid applications and presents performance results of our TLS implementation. Our analysis shows that given an appropriate implementation and configuration, deploying TLS in constrained smart metering systems is possible with acceptable overhead.     

Connectivity of workflow nets: the foundations of stepwise verification

Behavioral models capture operational principles of real-world or designed systems. Formally, each behavioral model defines the state space of a system, i.e., its states and the principles of state transitions. Such a model is the basis for analysis of the system’s properties. In practice, state spaces of systems are immense, which results in huge computational complexity for their analysis. Behavioral models are typically described as executable graphs, whose execution semantics encodes a state space. The structure theory of behavioral models studies the relations between the structure of a model and the properties of its state space. In this article, we use the connectivity property of graphs to achieve an efficient and extensive discovery of the compositional structure of behavioral models; behavioral models get stepwise decomposed into components with clear structural characteristics and inter-component relations. At each decomposition step, the discovered compositional structure of a model is used for reasoning on properties of the whole state space of the system. The approach is exemplified by means of a concrete behavioral model and verification criterion. That is, we analyze workflow nets, a well-established tool for modeling behavior of distributed systems, with respect to the soundness property, a basic correctness property of workflow nets. Stepwise verification allows the detection of violations of the soundness property by inspecting small portions of a model, thereby considerably reducing the amount of work to be done to perform soundness checks. Besides formal results, we also report on findings from applying our approach to an industry model collection.     

New high-spin bis-o-semiquinonato cobalt(II) complexes with neutral donor ligands

Two novel bis-o-semiquinonato cobalt complexes Co(3,6-SQ)₂L (1, L¹ = 2,6-dimethyl-N-(pyridin-2-ylmethylene)benzenamine; 2, L² = 2,6-dimethyl-N-(thiophen-2-ylmethylene)benzenamine; 3,6-SQ is 3,6-di-tert-butyl-o-benzosemiquinonato radical-anion) were synthesized. According to X-ray analysis, complex 2 adopts square pyramidal geometry with N-coordinated neutral ligand L² in the apical site. According to magnetic susceptibility measurements and spectroscopic studies, both complexes contain high-spin cobalt(II) (d⁷, S = 3/2) and two radical-anionic o-semiquinonato ligands. There is antiferromagnetic metal–ligand and ligand–ligand coupling in 1, while complex 2 demonstrates weak antiferromagnetic ligand–ligand coupling at low temperature and ferromagnetic metal–ligand exchange at 150–300 K.     

The role of fear and expectancies in capture of covert attention by spiders.

Fear-related stimuli are often prioritized during visual selection but it remains unclear whether capture by salient objects is more likely to occur when individuals fear those objects. In this study, participants with high and low fear of spiders searched for a circle while on some trials a completely irrelevant fear-related (spider) or neutral distractor (butterfly/leaf) was presented simultaneously in the display. Our results show that when you fear spiders and you are not sure whether a spider is going to be present, then any salient distractor (i.e., a butterfly) grabs your attention, suggesting that mere expectation of a spider triggered compulsory monitoring of all irrelevant stimuli. However, neutral stimuli did not grab attention when high spider fearful people knew that a spider could not be present during a block of trials, treating the neutral stimuli just as the low spider fearful people do. Our results show that people that fear spiders inspect potential spider-containing locations in a compulsory fashion even though directing attention to this location is completely irrelevant for the task. Reduction of capture can only be accomplished when people that fear spiders do not expect a spider to be present. (PsycINFO Database Record (c) 2011 APA, all rights reserved)