Complexation of Ni(II) by Dimethylglyoxime for Rapid Removal and Monitoring of Ni(II) in Water

The complexation of Ni(II) with dimethylglyoxime (DMG) entrapped within a Nafion membrane and a DMG–sol–gel matrix was studied and compared for different solutions. First and pseudo-second order kinetic models, Elovich, intra-particle, and liquid film diffusion models were applied to evaluate sorption kinetics. Complexation of Ni(II) by DMG entrapped in the polymeric materials followed a pseudo-second order kinetic model; moreover, DMG in Nafion also allowed diffusion-controlled uptake. The pseudo-second order rate constant was significantly higher for the free ligand in solution than for Ni(II) accumulation in the surface-attached DMG-Nafion. The DMG–sol–gel removal ability of Ni(II) was tested using actual mine water. The presence of interferences only insignificantly decreased the removal percentage of Ni(II), thus confirming the high selectivity of DMG towards Ni(II). Also, an electrochemical sensor modified with DMG in Nafion was investigated further for direct electrochemical determination of Ni(II) in untreated mine water. Determination errors and interference effects were low. Thus, this approach represents an effective potential solution for selective Ni(II) removal from mine water as well as a rapid and cheap sensor for on-site monitoring of Ni(II) in mine and environmental waters.     

Electrochemical Monitoring of Nickel(II) in Mine Water

This paper presents preliminary results in the development of a method for rapid real-time monitoring of Ni(II) in mine water. A simple electrochemical approach using a differential pulse voltammetry was developed and demonstrated by analysis of real samples.     

Quantitative Insight into the Design of Compounds Recognized by the L‐Type Amino Acid Transporter 1 (LAT1)

L ‐Type amino acid transporter 1 (LAT1) is a transmembrane protein expressed abundantly at the blood–brain barrier (BBB), where it ensures the transport of hydrophobic acids from the blood to the brain. Due to its unique substrate specificity and high expression at the BBB, LAT1 is an intriguing target for carrier‐mediated transport of drugs into the brain. In this study, a comparative molecular field analysis (CoMFA) model with considerable statistical quality (Q²=0.53, R²=0.75, Q² SE=0.77, R² SE=0.57) and good external predictivity (CCC=0.91) was generated. The model was used to guide the synthesis of eight new prodrugs whose affinity for LAT1 was tested by using an in situ rat brain perfusion technique. This resulted in the creation of a novel LAT1 prodrug with L ‐tryptophan as the promoiety; it also provided a better understanding of the molecular features of LAT1‐targeted high‐affinity prodrugs, as well as their promoiety and parent drug. The results obtained will be beneficial in the rational design of novel LAT1‐binding prodrugs and other compounds that bind to LAT1.     

Engaging the public with online discussion and spatial annotations: The generation and transformation of public knowledge

Online discussion with spatial annotations has been proposed as a method of facilitating public participation in spatial planning. It has been assumed that it will widen the knowledge base behind decisions by bringing local, first-hand knowledge into planning. However, what type of knowledge will be generated by such a geographically referenced public discussion in the planning process? This article addresses this question by tracing how an online discussion that allowed spatial annotations was implemented in a real-life land-use planning process in Tampere, Finland. The analysis focuses on two distinct phases of knowledge production. First, discussion focuses on how establishing this particular technology as a public forum impacts on the type of knowledge that is provided by the participants. The second part of the study addresses how planners assimilate information from geo-referenced public discussion. The article suggests that the interplay between (1) the site of knowledge production that was at the same time the arena of public discussion, (2) the issues that were deemed necessary to be cared for publicly, and (3) the people who were willing and able to enter the public arena and address issues in the way that the public arena afforded was crucial in shaping the type of knowledge that was generated. Furthermore, the results suggest that the constraints set by the local planning procedures and practical work of planners effectively guide the transformation of this knowledge into the domain of planning. The article starts to unravel contingencies of knowledge production related to public participation methods which use online discussion and spatial annotations.     

Alternative mechanisms of increased eggshell hardness of avian brood parasites relative to host species

Obligate brood parasitic birds lay their eggs in nests of other species and parasite eggs typically have evolved greater structural strength relative to host eggs. Increased mechanical strength of the parasite eggshell is an adaptation that can interfere with puncture ejection behaviours of discriminating hosts. We investigated whether hardness of eggshells is related to differences between physical and chemical traits from three different races of the parasitic common cuckoo Cuculus canorus, and their respective hosts. Using tools developed for materials science, we discovered a novel correlate of increased strength of parasite eggs: the common cuckoo''s egg exhibits a greater microhardness, especially in the inner region of the shell matrix, relative to its host and sympatric non-host species. We then tested predictions of four potential mechanisms of shell strength: (i) increased relative thickness overall, (ii) greater proportion of the structurally harder shell layers, (iii) higher concentration of inorganic components in the shell matrix, and (iv) elevated deposition of a high density compound, MgCO₃, in the shell matrix. We confirmed support only for hypothesis (i). Eggshell characteristics did not differ between parasite eggs sampled from different host nests in distant geographical sites, suggesting an evolutionarily shared microstructural mechanism of stronger parasite eggshells across diverse host-races of brood parasitic cuckoos.     

Input selection and shrinkage in multiresponse linear regression

The regression problem of modeling several response variables using the same set of input variables is considered. The model is linearly parameterized and the parameters are estimated by minimizing the error sum of squares subject to a sparsity constraint. The constraint has the effect of eliminating useless inputs and constraining the parameters of the remaining inputs in the model. Two algorithms for solving the resulting convex cone programming problem are proposed. The first algorithm gives a pointwise solution, while the second one computes the entire path of solutions as a function of the constraint parameter. Based on experiments with real data sets, the proposed method has a similar performance to existing methods. In simulation experiments, the proposed method is competitive both in terms of prediction accuracy and correctness of input selection. The advantages become more apparent when many correlated inputs are available for model construction.     

A density based segmentation method to determine the coordination number of a particulate system

The coordination number is an important parameter for understanding the particulate systems, especially when agglomerated particles are present. However, experimental determination of the coordination number is not trivial. In this study, we describe a 3D classification method, which is based on the revised DBSCAN (Density-Based Spatial Clustering of Applications with Noise) and its application to X-ray micro-tomographic (XMT) images to determine the coordination number distribution. Pellets of micro-crystalline cellulose were used as model particles. The validity of the segmentation was checked by comparing the particle size distribution (PSD) obtained by XMT-DBSCAN with PSD obtained by optical microscopy. The results were found to be in good agreement, demonstrating the suitability of the DBSCAN method. The means and standard deviations of coordination numbers were (8.2±1.7, n=994 particles), (8.1±1.5, n=904) and (6.2±1.2, n=159) for pellets with length based mean sizes of 157, 307 and 437 μm, respectively. The coordination number distribution was in line with previous finding in mono-sized acrylic beads.     

On the power of L-systems in image generation

Image generation with DOL-systems is discussed. It is shown that, if either the vector or the turtle geometry interpretation is used, DOL-systems can produce step-by-step all images that can be generated by regular languages (or by equivalent Iterative Matrix Homomorphisms of Shallit and Stolfi). An extension of turtle geometry interpretation is introduced that enables L-systems to generate gray-tone images. It is shown that with our extension every Weighted Finite Automaton can be simulated step-by-step by a DOL-system.An abbreviated version of this paper was presented at the conference Developments in Formal Languages, Turku, July 1993.Research supported by the NSF Grant No. CCR-9202396This article was processed by the author using the LATEX style file pljourl from Springer-Verlag.