Adsorption and photocatalysed destruction of cationic and anionic dyes on mesoporous titania films: Reactions at the air-solid interface

Cationic dyes, such as methylene blue (MB), Thionine (TH) and Basic Fuschin (BF), but not anionic dyes, such as Acid Orange 7 (AO7), Acid Blue 9 (AB9) and Acid Fuschin (AF), are readily adsorbed onto mesoporous titania films at high pH (pH 11), i.e. well above the pzc of titania (pH 6.5), due to electrostatic forces of attraction and repulsion, respectively. The same anionic dyes, but not the cationic dyes, are readily adsorbed on the same titania films at low pH (pH 3), i.e. well below titania's pzc. MB appears to adsorb on mesoporous titania films at pH 11 as the trimer (lambda(max) = 570 nm) but, upon drying, although the trimer still dominates, there is an absorption peak at 665 nm, especially notable at low [MB], which may be due to the monomer, but more likely MB J-aggregates. In contrast, the absorption spectrum of AO7 adsorbed onto the mesoporous titania film at low pH is very similar to the dye monomer. For both MB and AO7 the kinetics of adsorption are first order and yield high rate constants (3.71 and 1.481 g(-1) min(-1)), indicative of a strong adsorption process. Indeed, both MB and AO7 stained films retained much of their colour when left overnight in dye-free pH 11 and 3 solutions, respectively, indicating the strong nature of the adsorption. The kinetics of the photocatalytic bleaching of the MB-titania films at high pH are complex and not well-described by the Julson-Ollis kinetic model [A.J. Julson, D.F. Ollis, Appl. Catal. B. 65 (2006) 315]. Instead, there appears to be an initial fast but not simple demethylation step, followed by a zero-order bleaching and further demethylation steps. In contrast, the kinetics of photocatalytic bleaching of the AO7-titania film give a good fit to the Julson-Ollis kinetic model, yielding values for the various fitting parameters not too dissimilar to those reported for AO7 adsorbed on P25 titania powder. (C) 2008 Elsevier B.V. All rights reserved.

Functional and biochemical characterisation of the Escherichia coli major facilitator superfamily multidrug transporter MdtM

Multidrug resistance (MDR) occurs when bacteria simultaneously acquire resistance to a broad spectrum of structurally dissimilar compounds to which they have not previously been exposed. MDR is principally a consequence of the active transport of drugs out of the cell by proteins that are integral membrane transporters. We characterised and purified the putative Escherichia coli MDR transporter, MdtM, a 410 amino acid residue protein that belongs to the large and ubiquitous major facilitator superfamily. Functional characterisation of MdtM using growth inhibition and whole cell transport assays revealed its role in intrinsic resistance of E. coli cells to the antimicrobials ethidium bromide and chloramphenicol. Site-directed mutagenesis studies implied that the MdtM aspartate 22 residue and the highly conserved arginine at position 108 play a role in proton recognition. MdtM was homologously overexpressed and purified to homogeneity in dodecyl maltopyranoside detergent solution and the oligomeric state and stability of the protein in a variety of detergent solutions was investigated using size-exclusion HPLC. Purified MdtM is monomeric and stable in dodecyl maltopyranoside solution and binds chloramphenicol with nanomolar affinity in the same detergent. This work provides a firm foundation for structural studies on this class of multidrug transporter protein.

COMPARISON OF THE GROWTH INHIBITORY AND BACTERIOCIDAL EFFECTS OF TAUROLIDINE AND TAURULTAM ON A CLINICAL ISOLATE OF ESCHERICHIA-COLI

To investigate the mode of action of Taurolin, an antimicrobial preparation, the growth inhibitory and bacteriocidal effects of taurolidine and taurultam solutions on Escherichia coli isolated from a diagnosed urinary tract infection were examined at 37-degrees-C. The inhibitory effects of taurolidine solutions were observed to be greater than those of taurultam solutions at comparative concentrations; however, the presence of sublethal concentrations of formaldehyde (methylene glycol) associated with taurolidine was sufficient to account for this. The bacteriocidal activity of taurolidine (2.0% w/v) was greater than that of taurultam (4.5% w/v). Both compounds produced biphasic death rates with dissimilar initial slopes, suggested to be due to the presence of formaldehyde in taurolidine solutions. These observations indicate that the growth inhibitory and bacteriocidal effects of Taurolin solutions are primarily due to taurultam, however, the presence of sublethal concentrations of formaldehyde is significant in the expression of this activity.

The pmrF polymyxin-resistance operon of Yersinia pseudotuberculosis is upregulated by the PhoP-PhoQ two-component system but not by PmrA-PmrB, and is not required for virulence

The Yersinia pseudotuberculosis chromosome contains a seven-gene polycistronic unit (the pmrF operon) whose products share extensive homologies with their pmrF counterparts in Salmonella enterica serovar Typhimurium (S. typhimurium), another Gram-negative bacterial enteropathogen. This gene cluster is essential for addition of 4-aminoarabinose to the lipid moiety of LPS, as demonstrated by MALDI-TOF mass spectrometry of lipid A from both wild-type and pmrF-mutated strains. As in S. typhimurium, 4-aminoarabinose substitution of lipid A contributes to in vitro resistance of Y. pseudotuberculosis to the antimicrobial peptide polymyxin B. Whereas pmrF expression in S. typhimurium is mediated by both the PhoP-PhoQ and PmrA-PmrB two-component regulatory systems, it appears to be PmrA-PmrB-independent in Y. pseudotuberculosis, with the response regulator PhoP interacting directly with the pmrF operon promoter region. This result reveals that the ubiquitous PmrA-PmrB regulatory system controls different regulons in distinct bacterial species. In addition, pmrF inactivation in Y. pseudotuberculosis has no effect on bacterial virulence in the mouse, again in contrast to the situation in S. typhimurium. The marked differences in pmrF operon regulation in these two phylogenetically close bacterial species may be related to their dissimilar lifestyles.

Protecting group and switchable pore-discriminating adsorption properties of a hydrophilic-hydrophobic metal-organic framework

Formed by linking metals or metal clusters through organic linkers, metal-organic frameworks are a class of solids with structural and chemical properties that mark them out as candidates for many emerging gas storage, separation, catalysis and biomedical applications. Important features of these materials include their high porosity and their flexibility in response to chemical or physical stimuli. Here, a copper-based metal-organic framework has been prepared in which the starting linker (benzene-1,3,5-tricarboxylic acid) undergoes selective monoesterification during synthesis to produce a solid with two different channel systems, lined by hydrophilic and hydrophobic surfaces, respectively. The material reacts differently to gases or vapours of dissimilar chemistry, some stimulating subtle framework flexibility or showing kinetic adsorption effects. Adsorption can be switched between the two channels by judicious choice of the conditions. The monoesterified linker is recoverable in quantitative yield, demonstrating possible uses of metal-organic frameworks in molecular synthetic chemistry as 'protecting groups' to accomplish selective transformations that are difficult using standard chemistry techniques.

Compositional Divergence and Convergence in Local Communities and Spatially Structured Landscapes

Community structure depends on both deterministic and stochastic processes. However, patterns of community dissimilarity (e.g. difference in species composition) are difficult to interpret in terms of the relative roles of these processes. Local communities can be more dissimilar (divergence) than, less dissimilar (convergence) than, or as dissimilar as a hypothetical control based on either null or neutral models. However, several mechanisms may result in the same pattern, or act concurrently to generate a pattern, and much research has recently been focusing on unravelling these mechanisms and their relative contributions. Using a simulation approach, we addressed the effect of a complex but realistic spatial structure in the distribution of the niche axis and we analysed patterns of species co-occurrence and beta diversity as measured by dissimilarity indices (e.g. Jaccard index) using either expectations under a null model or neutral dynamics (i.e., based on switching off the niche effect). The strength of niche processes, dispersal, and environmental noise strongly interacted so that niche-driven dynamics may result in local communities that either diverge or converge depending on the combination of these factors. Thus, a fundamental result is that, in real systems, interacting processes of community assembly can be disentangled only by measuring traits such as niche breadth and dispersal. The ability to detect the signal of the niche was also dependent on the spatial resolution of the sampling strategy, which must account for the multiple scale spatial patterns in the niche axis. Notably, some of the patterns we observed correspond to patterns of community dissimilarities previously observed in the field and suggest mechanistic explanations for them or the data required to solve them. Our framework offers a synthesis of the patterns of community dissimilarity produced by the interaction of deterministic and stochastic determinants of community assembly in a spatially explicit and complex context.

Aspasing Out Metacaspases and Caspases: Proteases of Many Trades

Execution of programmed cell death (PCD) in nonmetazoan organisms is morphologically different from apoptotic PCD in animals and lacks a number of key molecular components of apoptotic machinery, including caspases. Yet protozoan, fungal, and plant cells exhibit caspase-like proteolytic activities, which increase in a PCD-dependent manner. This poses a question whether nonmetazoan organisms contain structurally dissimilar proteases that functionally substitute for caspases. Putative ancestors of caspases, metacaspases, are candidates for this role; however, their distinct substrate specificity raises doubts. The identification of a common biological target of caspases and metacaspases and previously unknown functions unrelated to cell death of metacaspases provide new food for thought.

'Translated Verse': Milton's Latin Poetry in the Long Eighteenth Century

This chapter assesses ways in which the emergence in the long eighteenth century of a cluster of verse translations of Milton’s Poemata engendered an intellectual discourse and debate on translation itself, not dissimilar to the magazine warfare of the day. It argues that poetical renderings of Milton’s Latin verse, and the biographical and literary contexts in which they appeared, facilitated the interrogation of key issues that are still being debated by modern translation theorists: the nature and function of translation; the viability of rendering a source text in a target language that is also in this instance a poetic language; the potential ‘fetters’ which, in Drydenesque terms, might constrain ‘the verbal copier’; or by contrast the quasi-liberating fluency, the ‘fluent strategy’, attendant upon recourse to verse as translational medium; canonicity, amplification and omission; the much-debated issue of authorial equivalence, evinced here, it is suggested, by the editorial showcasing of the translator; and not least, the perennial question of translation as reading and critical interpretation. In short, verse renderings of Milton’s Latin poetry and the debates that they engendered assume a not inconsequential place in the history of translation theory, which, as Venuti notes, is forever concerned with ‘the changing relationships between the relative autonomy of the translated text and two other categories: equivalence and function.’

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Novel hydrolysis-probe based qPCR assay to detect saxitoxin transcripts of dinoflagellates in environmental samples

Paralytic Shellfish Poisoning (PSP) is a serious human illness caused by ingestion of seafood enriched with paralytic shellfish toxins (PSTs). PSTs are neurotoxic compounds produced by marine dinoflagellates, specifically by Alexandrium spp., Gymnodinium catenatum and Pyrodinium bahamense. Every year, massive monitoring of PSTs and their producers is undertaken worldwide to avoid PSP incidences. Here we developed a sensitive, hydrolysis probe-based quantitative PCR (qPCR) assay to detect a gene essential for PST synthesis across different dinoflagellate species and genera and tested it on cDNA generated from environmental samples spiked with Alexandrium minutum or Alexandrium fundyense cells. The assay was then applied to two environmental sample series from Norway and Spain and the results were complemented with cell counts, LSU-based microarray data and toxin measurements (enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) biosensor method). The overall agreement between the results of the qPCR assay and the complementary data was good. The assay reliably detected sxtA transcripts from Alexandrium spp. and G. catenatum, even though Alexandrium spp. cell concentrations were mostly so low that they could not be quantified microscopically. Agreement between the novel assay and toxin measurements or cell counts was generally good; the few inconsistencies observed were most likely due to disparate residence times of sxtA transcripts and PSTs in seawater, or, in the case of cell counts, to dissimilar sxtA4 transcript numbers per cell in different dinoflagellate strains or species. © 2013 Elsevier B.V.

Further refinement of the nature of the communication impairment in Cornelia de Lange syndrome

Purpose – Research into the communication skills of individuals with Cornelia de Lange syndrome (CdLS) is extremely limited. This paper aims to evaluate the nature of these skills and impairments in CdLS using a detailed informant assessment of pre-verbal communication skills.
Design/methodology/approach – The study used the Pre-verbal Communication Schedule to evaluate communication skills in individuals with CdLS (n ¼ 14), aged five to14 years. The group was compared with a contrast group of individuals with Cri du Chat syndrome (CdCS; n ¼ 14) who were matched for age and intellectual ability.
Findings – A significant difference was identified in understanding non-vocal communication (p , 0.005), with the CdLS group showing a greater deficit. These findings indicate the presence of a syndrome-specific deficit in understanding non-verbal communication in individuals with CdLS and suggest that there may be a dissociation between the processing of verbal and non-verbal communication.
Originality/value – The findings indicate that, in many ways, these two syndrome groups are not dissimilar in terms of their communication skills. However, individuals with CdLS show a syndrome-specific deficit in understanding non-vocal communication relative to the CdCS group.

Selective High Impedance Surface Active Region Loading of Archimedean Spiral Antenna

We show that a significant increase in the gain and front-to-back ratio is obtained when different high impedance surface (HIS) sections are placed below the active regions of an Archimedean spiral antenna. The principle of operation is demonstrated at 3, 6, and 9 GHz for an antenna design that employs a ground plane composed of two dissimilar HISs. The unit cells of the HISs are collocated and resonant at the same frequency as the 3- and 6-GHz active regions of the wideband spiral. It is shown that the former HIS must also be designed to resonate at 9 GHz to avoid the generation of a boresight null that occurs because the structure is physically large enough to support higher-order modes. The improvement that is obtained at each of the three frequencies investigated is shown by comparing the predicted and measured radiation patterns for the free space and HIS-backed antenna.

Stability of 71 degrees stripe domains in epitaxial BiFeO3 films upon repeated electrical switching

The 71 degrees stripe domain patterns of epitaxial BiFeO3 thin films are frequently being explored to achieve new functional properties, dissimilar from the BiFeO3 bulk properties. We show that in-plane switching and out-of-plane switching of these domains behave very differently. In the in-plane configuration the domains are very stable, whereas in the out-of-plane configuration the domains change their size and patterns, depending on the applied switching voltage frequency.

Physical Layer Secrecy Performance over Rayleigh/Rician Fading Channels

In this paper, we investigate the physical layer secrecy performance of a single-input single-output system that consists of single antenna devices and operates in the presence of a single antenna passive eavesdropper over dissimilar fading channels. In particular, we consider two scenarios in terms of dissimilar fading channel arrangements: the legal/illegal channels are subject to Rayleigh/Rician fading, respectively; and the legal/illegal channels are subject to Rician/Rayleigh fading, respectively. Specifically, analytical expressions for the probability of the existence of a non-zero secrecy capacity and the secrecy outage probability are derived by using statistical characteristics of the signal-to-noise ratio. Numerical results are provided for selected scenarios to illustrate applications of the developed analytical expressions.

A systematic review of midwife led interventions to address post traumatic stress syndrome

Objective
to systematically identify interventions that midwives could introduce to address post-traumatic stress in women following childbirth.

Methods
a search strategy was developed and relevant papers were identified from databases including Cinahl, Cochrane Library, EMBASE, Maternity and Infant Care, MEDLINE, PsycINFO, and Web of Science. Key search terms used were post-traumatic stress, post partum, intervention, controlled trial and review. Papers eligible for inclusion were primary studies and reviews of research published from 2002–2012, focusing on interventions which could be implemented by midwives for the prevention and/or management of PTSD. For primary studies, RCTs, controlled clinical trials, and cohort studies with a control group were eligible. Eligible reviews were those with a specified search strategy and inclusion/exclusion criteria. Methodological quality was assessed using recognised frameworks.

Findings
six primary studies and eight reviews were eligible for inclusion. The majority of included studies or reviews focused on debriefing and/or counselling interventions; however the results were not consistent due to significant variation in methodological quality and use of dissimilar interventions. Two of the reviews considered the general management of post partum PTSD and one broadly covered anxiety during pregnancy and the post partum, incorporating a section on PTSD. The majority of women reported that the opportunity to discuss their childbirth experience was subjectively beneficial.

Conclusions and implications for practice
no evidence-based midwifery interventions were identified from this systematic review that can be recommended for introduction into practice to address PTSD. It is recommended that future research in this area should incorporate standardised interventions with similar outcome measures to facilitate synthesis of results. Further research on interventions used in non-maternity populations is needed in order to confirm their usefulness in addressing post partum PTSD.

Combinatorial Frequency Generation in Quasi-Periodic Stacks of Nonlinear Dielectric Layers

Three-wave mixing in quasi-periodic structures (QPSs) composed of nonlinear anisotropic dielectric layers, stacked in Fibonacci and Thue-Morse sequences, has been explored at illumination by a pair of pump waves with dissimilar frequencies and incidence angles. A new formulation of the nonlinear scattering problem has enabled the QPS analysis as a perturbed periodic structure with defects. The obtained solutions have revealed the effects of stack composition and constituent layer parameters, including losses, on the properties of combinatorial frequency generation (CFG). The CFG features illustrated by the simulation results are discussed. It is demonstrated that quasi-periodic stacks can achieve a higher efficiency of CFG than regular periodic multilayers.