Nanofiltration applications of tough MWNT buckypaper membranes containing biopolymers

© 2017 Elsevier B.V. The ability of biopolymers (bovine serum albumin, lysozyme, chitosan, gellan gum and DNA) to facilitate formation of aqueous dispersions of MWNTs was investigated using a combination of absorption spectrophotometry and optical microscopy. Subsequently, self-supporting carbon nanotube membranes, known as buckypapers (BPs), were prepared by vacuum filtration of the dispersions. Microanalytical data obtained from the BPs confirmed the retention of biopolymers within their structures. Tensile test measurements performed on the BPs showed that incorporation of the biopolymers resulted in significant improvements in mechanical properties, compared to analogous BPs containing MWNTs and the low molecular mass dispersant Triton X-100. For example, MWNT/CHT BPs (CHT=chitosan) exhibited values for tensile strength, ductility, Young's modulus and toughness of 28±2 MPa, 5.3±2.7%, 0.9±0.3 GPa and 1.7±0.3 J g−1, respectively. Each of these values are significantly greater than those obtained for MWNT/Trix BPs, prepared using a low molecular weight dispersant (6±3 MPa, 1.3±0.2%, 0.6±0.3 GPa and 0.10±0.06 J g−1, respectively). This significant improvement in mechanical properties is attributed to the ability of the long biopolymer molecules to act as flexible bridges between the short CNTs. All BPs possessed hydrophilic surfaces, with contact angles ranging from 29±2° to 57±5°. Nitrogen gas porosimetry showed that the BPs have highly porous internal structures, while scanning electron microscopy (SEM) showed their surface morphologies have numerous pore openings. The permeability of the BPs towards water, inorganic salts, and dissolved trace organic contaminants (TrOCs), such as pharmaceuticals, personal care products, and pesticides, was investigated through filtration experiments. Of the twelve TrOCs investigated in this study, nine were rejected by more than 95% by BPs composed of MWNTs and chitosan. The latter BPs also demonstrated good rejection of both NaCl (30–55%) and MgSO4(40–70%)

Accidental finding of a toothpick in the porta hepatis during laparoscopic cholecystectomy: a case report

<p>Abstract</p> <p>Introduction</p> <p>Unintentional ingestion of a toothpick is not an uncommon event. Often the ingested toothpicks spontaneously pass through the gut without sequelae. However, serious complications can happen when these sharp objects migrate through the gastrointestinal wall.</p> <p>Case presentation</p> <p>In the current report, we describe the case of a 37-year-old Caucasian woman with an incidental finding of a toothpick in the porta hepatis during laparoscopic cholecystectomy for symptomatic gall stones.</p> <p>Conclusion</p> <p>Toothpick ingestion is not an uncommon event and can predispose patients to serious complications. In this particular case, the toothpick was only discovered at the time of unrelated surgery. Therefore, it was important during surgery to exclude any related or missed injury to the adjacent structures by this sharp object.</p

Comparative genomics of isolates of a pseudomonas aeruginosa epidemic strain associated with chronic lung infections of cystic fibrosis patients

Pseudomonas aeruginosa is the main cause of fatal chronic lung infections among individuals suffering from cystic fibrosis (CF). During the past 15 years, particularly aggressive strains transmitted among CF patients have been identified, initially in Europe and more recently in Canada. The aim of this study was to generate high-quality genome sequences for 7 isolates of the Liverpool epidemic strain (LES) from the United Kingdom and Canada representing different virulence characteristics in order to: (1) associate comparative genomics results with virulence factor variability and (2) identify genomic and/or phenotypic divergence between the two geographical locations. We performed phenotypic characterization of pyoverdine, pyocyanin, motility, biofilm formation, and proteolytic activity. We also assessed the degree of virulence using the Dictyostelium discoideum amoeba model. Comparative genomics analysis revealed at least one large deletion (40-50 kb) in 6 out of the 7 isolates compared to the reference genome of LESB58. These deletions correspond to prophages, which are known to increase the competitiveness of LESB58 in chronic lung infection. We also identified 308 non-synonymous polymorphisms, of which 28 were associated with virulence determinants and 52 with regulatory proteins. At the phenotypic level, isolates showed extensive variability in production of pyocyanin, pyoverdine, proteases and biofilm as well as in swimming motility, while being predominantly avirulent in the amoeba model. Isolates from the two continents were phylogenetically and phenotypically undistinguishable. Most regulatory mutations were isolate-specific and 29% of them were predicted to have high functional impact. Therefore, polymorphism in regulatory genes is likely to be an important basis for phenotypic diversity among LES isolates, which in turn might contribute to this strain's adaptability to varying conditions in the CF lung

Strengthening the research to policy and practice interface: exploring strategies used by research organisations working on sexual and reproductive health and HIV/AIDS

This commentary introduces the HARPS supplement on getting research into policy and practice in sexual and reproductive health (SRH). The papers in this supplement have been produced by the Sexual Health and HIV Evidence into Practice (SHHEP) collaboration of international research, practitioner and advocacy organizations based in research programmes funded by the UK Department for International Development

Identification of NAD interacting residues in proteins

Background: Small molecular cofactors or ligands play a crucial role in the proper functioning of cells. Accurate annotation of their target proteins and binding sites is required for the complete understanding of reaction mechanisms. Nicotinamide adenine dinucleotide (NAD+ or NAD) is one of the most commonly used organic cofactors in living cells, which plays a critical role in cellular metabolism, storage and regulatory processes. In the past, several NAD binding proteins (NADBP) have been reported in the literature, which are responsible for a wide-range of activities in the cell. Attempts have been made to derive a rule for the binding of NAD+ to its target proteins. However, so far an efficient model could not be derived due to the time consuming process of structure determination, and limitations of similarity based approaches. Thus a sequence and non-similarity based method is needed to characterize the NAD binding sites to help in the annotation. In this study attempts have been made to predict NAD binding proteins and their interacting residues (NIRs) from amino acid sequence using bioinformatics tools. Results: We extracted 1556 proteins chains from 555 NAD binding proteins whose structure is available in Protein Data Bank. Then we removed all redundant protein chains and finally obtained 195 non-redundant NAD binding protein chains, where no two chains have more than 40% sequence identity. In this study all models were developed and evaluated using five-fold cross validation technique on the above dataset of 195 NAD binding proteins. While certain type of residues are preferred (e.g. Gly, Tyr, Thr, His) in NAD interaction, residues like Ala, Glu, Leu, Lys are not preferred. A support vector machine (SVM) based method has been developed using various window lengths of amino acid sequence for predicting NAD interacting residues and obtained maximum Matthew's correlation coefficient (MCC) 0.47 with accuracy 74.13% at window length 17. We also developed a SVM based method using evolutionary information in the form of position specific scoring matrix (PSSM) and obtained maximum MCC 0.75 with accuracy 87.25%. Conclusion: For the first time a sequence-based method has been developed for the prediction of NAD binding proteins and their interacting residues, in the absence of any prior structural information. The present model will aid in the understanding of NAD+ dependent mechanisms of action in the cell. To provide service to the scientific community, we have developed a user-friendly web server, which is available from URL http://www.imtech.res.in/raghava/nadbinder/

Identification of Mannose Interacting Residues Using Local Composition

BACKGROUND: Mannose binding proteins (MBPs) play a vital role in several biological functions such as defense mechanisms. These proteins bind to mannose on the surface of a wide range of pathogens and help in eliminating these pathogens from our body. Thus, it is important to identify mannose interacting residues (MIRs) in order to understand mechanism of recognition of pathogens by MBPs. RESULTS: This paper describes modules developed for predicting MIRs in a protein. Support vector machine (SVM) based models have been developed on 120 mannose binding protein chains, where no two chains have more than 25% sequence similarity. SVM models were developed on two types of datasets: 1) main dataset consists of 1029 mannose interacting and 1029 non-interacting residues, 2) realistic dataset consists of 1029 mannose interacting and 10320 non-interacting residues. In this study, firstly, we developed standard modules using binary and PSSM profile of patterns and got maximum MCC around 0.32. Secondly, we developed SVM modules using composition profile of patterns and achieved maximum MCC around 0.74 with accuracy 86.64% on main dataset. Thirdly, we developed a model on a realistic dataset and achieved maximum MCC of 0.62 with accuracy 93.08%. Based on this study, a standalone program and web server have been developed for predicting mannose interacting residues in proteins (http://www.imtech.res.in/raghava/premier/). CONCLUSIONS: Compositional analysis of mannose interacting and non-interacting residues shows that certain types of residues are preferred in mannose interaction. It was also observed that residues around mannose interacting residues have a preference for certain types of residues. Composition of patterns/peptide/segment has been used for predicting MIRs and achieved reasonable high accuracy. It is possible that this novel strategy may be effective to predict other types of interacting residues. This study will be useful in annotating the function of protein as well as in understanding the role of mannose in the immune system

"Who am I? Where am I?" Experiences of married young women in a slum in Islamabad, Pakistan

Background: According to the cultural tradition in Pakistan, young women belonging to poor families should marry shortly after menarche. However, existing data show that young people, especially women, are not prepared for sexual life and have poor knowledge about sexuality and reproductive health. Many of the difficulties young women experience are related to beliefs and expectations in the society related to their reproductive roles making them more vulnerable to reproductive ill health. Aim: The study explores the preparedness of young women for married life (communicating with spouse, initiation of sexual activity and child bearing) and ability to negotiate in marriage with spouse on number of children to have and on contraceptive use. Methods: In order to obtain an in-depth understanding of young women’s lives qualitative and quantitative approaches were used. Three qualitative studies using narrative and content analysis were carried out in a slum setting in the outskirts of Islamabad city in Pakistan. Married young women (I), unmarried young women (II) and parents (III) were selected with the help of a community worker. Young married women were interviewed three times at different occasions. Narrative structuring was used to explore how the participants represented their situation. In addition twenty qualitative interviews and three focus group discussions were conducted with young unmarried women (II). Twenty-five parents participated in four gender specific focus group discussions (III). Content analysis was used for analysis of study II and III. For the quantitative study (IV), a subset of 1803 married young women aged 15-24 years was drawn from a nationally representative adolescent and youth survey conducted in Pakistan in 2001-2002 by the Population Council. Regression models were used for analysing the following outcomes: reported agreement with spouse on the number of children to have, current use of contraceptives, intention to use contraceptives in the future and the time elapsed between marriage and the first contraceptive use. Key co-variates of interest were variables that measure the involvement of young women in their marriage as having a say in selection of spouse, mobility outside the household, social role and decision making in their homes. Results: The main theme in all the qualitative studies was ‘socialisation of young women into submissiveness’. For the married young women two themes were identified a) submissive-accepting and b) submissive-victims. The married young women who belonged to the accepting group lived under compromised conditions but described themselves as satisfied with their situation. Women belonging to the victimized group experienced physical and verbal abuse for their inability to cope with the duties of a wife, caretaker of the home and bearer of children. Their situation was compounded by the power dynamics within the household (I). For the unmarried young women the main theme identified was security lies in obedience. The two sub-themes contributing to the main theme were socialisation into submissiveness and transition into adulthood in silence (II). The theme and the sub-themes illustrate the situation of young women in a poor setting in Pakistan. The main theme identified in the study with the parents was ‘Good parents’ strive to raise ‘innocent daughters’. The three sub-themes contributing to the main theme were: a daughter - a responsibility and a burden, social and sexual innocence and parents’ roles in the preparation for marriage. The theme and the sub-themes illustrate how the parents saw themselves as responsible for raising ‘innocent daughters’ and arranging good marriages (III). The quantitative study on the married young women showed that having a say in the selection of spouse at the time of marriage was significantly associated with agreeing with spouse over the number of children to have, intention to use contraceptives and the time between marriage and first contraceptive use. These relationships existed after controlling for education, socioeconomic status, mobility outside of house and decision making in the home (IV). Conclusions: In a culture of silence around sexuality, young women’s socialisation into submissiveness lays the foundation for the lack of control over their future reproductive health (I and II). The parents realised, though, that bringing up daughters for marriage requires not only obedience, but also building confidence and knowledge during their childhood (III). Women who had decision making freedom in their parental home carried this ability with them into marriage in their new home and were better able to negotiate about their fertility (IV). Knowledge about reproductive life could prepare young women better for the future life and give them more control of their fertility. Innovative interventions targeting women need to challenge current societal norms of womanhood to promote the upbringing of confident and knowledgeable young women

'We Have the Internet in Our Hands’: Bangladeshi College Students’ Use of ICTs For Health Information

Information and Communications Technologies (ICTs) which enable people to access, use and promote health information through digital technology, promise important health systems innovations which can challenge gatekeepers’ control of information, through processes of disintermediation. College students, in pursuit of sexual and reproductive health (SRH) information, are particularly affected by gatekeeping as strong social and cultural norms restrict their access to information and services. This paper examines mobile phone usage for obtaining health information in Mirzapur, Bangladesh. It contrasts college students’ usage with that of the general population, asks whether students are using digital technologies for health information in innovative ways, and examines how gender affects this