Chitosan-based fiber-sponge materials as a promising tool for microalgae harvesting from Lake Baikal

Mass eutrophication of microalgae and cyanobacteria is observed in Lake Baikal in the past decade. In this paper, the concept of replaceable adsorption filter material based on chitosan flocculant filler and chlorinated polyvinyl chloride polymer nonwoven material are proposed. Functional and mechanical properties and morphology of the material are investigated depending on a packing density and a degree of chitosan filling. The introduction of 45% chitosan increases the Young's modulus up to 10 times, and it makes the material more rigid in 2.8 times. The high efficiency of sorption and growth inhibition of cumulative biomass culture was shown. The biomass source is taken from the coast of Barguzinsky Bay of Lake Baikal. Dominant species is microalgae of Scenedesmus genus.     

Structural Consequences of the 1,2,3-Triazole as an Amide Bioisostere in Analogues of the Cystic Fibrosis Drugs VX-809 and VX-770

Although the 1,2,3-triazole is a commonly used amide bioisostere in medicinal chemistry, the structural implications of this replacement have not been fully studied. Employing X-ray crystallography and computational studies, we report the spatial and electronic consequences of replacing an amide with the triazole in analogues of cystic fibrosis drugs in the VX-770 and VX-809 series. Crystallographic analyses quantify subtle differences in the relative positions and conformational preferences of the R¹ and R² substituents attached to the amide and triazole bioisosteres. Computational studies derived from the X-ray data highlight the improved hydrogen bonding donor and acceptor capabilities of the amide in comparison to the triazole. This analysis of the spatial and electronic differences between the amide and 1,2,3-triazole will inform medicinal chemists as they consider using the triazole as an amide bioisostere.     

Bacterial secretion of the Fab fragment of a mouse monoclonal IgM that reacts with IgG variable regions

In this report, we describe the expression system that enabledus to produce in Escherichia coli the Fab fragment of a mouseIgM that has previously been shown to inhibit the binding ofIgG to autoantigens by interacting with their variable regions.In our system, both light chain and heavy chain fragments wereput under the control of the malE promoter. The light chainwas fused to the MalE signal sequence, while the heavy chainvariable and first constant region were fused to the alkalinephosphatase signal sequence. In this system, after inductionof the promoter with maltose, the Fab fragment could be detectedin a periplasmic extract of the bacteria by Western blottingand also by ELISA. This Fab fragment was purified on a goatanti-mouse immunoglobulin immunoadsorbent and biotinylated.The Fab fragment produced by E.coli reacted with the trinitrophenyl(TNP) hapten and F(ab')₂ fragments of mouse IgG and these reactivitiescould be specifically inhibited by the corresponding solubleantigens. The dissociation constants of this Fab were 1.65 x10^–6 M for TNP and 5 x 10^–6 M for IgG F(ab')₂ fragments,indicating that the affinity of the Fab fragment compared withthat of the whole IgM molecule was similar for TNP but was lowerfor IgG F(ab')₂ fragments     

Microbial partitioning to settleable particles in stormwater

The degree to which microbes in the water column associate with settleable particles has important implications for microbial transport in receiving waters, as well as for microbial removal via sedimentation (i.e. detention basins). The partitioning behavior of several bacterial, protozoan and viral indicator organisms is explored in three urban streams under both storm and dry weather conditions. The fraction of organisms associated with settleable particles in stormwater is estimated through use of a centrifugation technique which is calibrated using suspensions of standard particles (e.g., glass, latex). The fraction of organisms associated with settleable particles varies by type of microbe, and the partitioning behavior of each organism generally changes between dry weather and storm conditions. Bacterial indicator organisms (fecal coliforms, Escherichia coli, enterococci) exhibited relatively consistent behavior, with an average of 20-35% of organisms associated with these particles in background samples and 30-55% in storm samples. Clostridium perfringens spores exhibited the highest average level of particle association, with storm values varying from 50% to 70%. Results related to total coliphage partitioning were more variable, with 20-60% associated with particles during storms. These estimates should be valuable in surface water quality modeling efforts, many of which currently assume that all microbes exist as free (unattached) organisms.     

Enhancement of etch rate for preparation of nano-sized ion-track membranes of poly(vinylidene fluoride): Effect of pretreatment and high-LET beam irradiation

We investigated how pretreatment and high-LET beam irradiation affected the ion-track dissolution rate in poly(vinylidene fluoride) (PVDF) films by SEM observations and conductometric analysis in order to develop the preparation methodology of nano-sized ion-track membranes. PVDF thin films irradiated with four types of ion beams were exposed to a 9 mol/dm³ KOH aqueous solution after their storage in air at 120 °C. This heating treatment was found to enhance the etch rate in the latent track, both in the inner core and outer halo regions, without changing that in the bulk, probably due to the formation of parasitic oxidation products facilitating the introduction of the etching agent to improve the etchability. Additionally, the irradiation of heavier higher-LET ions, causing each track to more activated sites (like radicals), was preferable for achieving effective etching.     

All‐subsets regression under effect heredity restrictions for experimental designs with complex aliasing

We consider an all‐subsets regression method for models under effect heredity restrictions for experimental designs with complex aliasing, whose number of potential main effects and two‐factor interactions exceed the number of runs. In this paper, we present an algorithm that systematically attempts to fit all such models. We illustrate the algorithm with two published experiments. Copyright © 2009 John Wiley & Sons, Ltd.     

A decision support system for coating selection based on fuzzy logic and multi-criteria decision making

Wear and corrosion are the most important factors that the surface of the engineering parts must confront. The need for protection and improvement of the mechanical characteristics of the surface of engineering parts can be to some extent satisfied by coatings. Coatings are considered as an excellent solution when resistance to corrosion, oxidation or low friction is demanded, but due the complexity of selecting the appropriate one, engineers often avoid them. The need for simultaneous consideration of qualitative and quantitative properties, render the use of classic material selection theories inadequate. An expert system for coating selection is presented in this paper, which can handle both qualitative and quantitative variables. The mathematical model used combines the multi-criteria decision making theories (MCDM) together with the fuzzy sets theory. The “Max-Min set” method is applied to calculate the ordering value of the alternatives while the TOPSIS method is used to rank them. A numerical example is provided to illustrate the method. Finally, the process presented can be easily computerized, to create the relative software.     

Aging and task switching: A meta-analysis.

A meta-analysis of 26 published articles (with 36 independent participant groups) was conducted to analyze the relationship between task-switching effects and aging. Latency served as the dependent measure. Multilevel modeling was used to test for additive and multiplicative complexity effects in local and global switch costs. Global task switching was found to add 1 or more stages to processing and resulted in a marked age deficit. Local task-switching costs, on the other hand, showed a multiplicative complexity effect but no specific attention-related age deficits. Cueing or switch predictability did not affect age differences. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Are working memory deficits in bipolar disorder markers for psychosis?

Working memory deficits have been identified in bipolar disorder, but there is evidence suggesting that these deficits may be markers for psychosis rather than affective disorder. The current study examined this issue by comparing two groups of individuals with bipolar disorder, one with psychotic features and one without psychotic features, with a group of normal controls. Working memory was conceptualized as a multicomponent system that includes auditory and visuospatial short-term stores, executive control processes, and an episodic buffer that allows for communication between short- and long-term memory stores (Baddeley & Logie, 1999). Results indicated that only executive control processes significantly differentiated the psychotic and nonpsychotic bipolar groups, although visuospatial working memory differentiated both bipolar groups from controls. The results support the idea that some aspects of working memory performance are markers for psychosis, while others may be more general markers for bipolar disorders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)