Progress in proton-conducting oxides as electrolytes for low-temperature solid oxide fuel cells: From materials to devices

Among various types of alternative energy devices, solid oxide fuel cells (SOFCs) operating at low temperatures (300-600°C) show the advantages for both stationary and mobile electricity production. Proton-conducting oxides as electrolyte materials play a critical role in the low-temperature SOFCs (LT-SOFCs). This review summarizes progress in proton-conducting solid oxide electrolytes for LT-SOFCs from materials to devices, with emphases on (1) strategies that have been proposed to tune the structures and properties of proton-conducting oxides and ceramics, (2) techniques that have been employed for improving the performance of the protonic ceramic-based SOFCs (known as PCFCs), and (3) challenges and opportunities in the development of proton-conducting electrolyte-based PCFCs

Facile one-pot synthesis of amoxicillin-coated gold nanoparticles and their antimicrobial activity

Nanomaterials have been the object of intense study due to promising applications in a number of different disciplines. In particular, medicine and biology have seen the potential of these novel materials with their nanoscale properties for use in diverse areas such as imaging, sensing and drug vectorisation. Gold nanoparticles (GNPs) are considered a very useful platform to create a valid and efficient drug delivery/carrier system due to their facile and well-studied synthesis, easy surface functionalization and biocompatibility. In the present study, stable antibiotic conjugated GNPs were synthesised by a one-step reaction using a poorly water soluble antibiotic, amoxicillin. Amoxicillin, a member of the penicillin family, reduces the chloroauric acid to form nanoparticles and at the same time coats them to afford the functionalised nanomaterial. A range of techniques including UV-vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) were used to ascertain the gold/drug molar ratio and the optimum temperature for synthesis of uniform monodisperse particles in the ca. 30-40 nm size range. Amoxicillin-conjugated gold showed an enhancement of antibacterial activity against Escherichia coli compared to the antibiotic alone

Antibiotic mediated synthesis of gold nanoparticles with potent antimicrobial activity and their application in antimicrobial coatings

We report a one-pot synthesis of spherical gold nanoparticles (52-22 nm) and their capping with cefaclor, a second-generation antibiotic, without use of other chemicals. The differently sized gold nanoparticles were fabricated by controlling the rate of reduction of gold ions in aqueous solution by varying the reaction temperature (20-70 C). The primary amine group of cefaclor acted as both the reducing and capping agent for the synthesis of gold nanoparticles leaving the b-lactam ring of cefaclor available for activity against microbes. Antimicrobial testing showed that cefaclor reduced gold nanoparticles have potent antimicrobial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria as compared to cefaclor or gold nanoparticles alone. The minimum inhibition concentrations (MICs) of cefaclor reduced gold nanoparticles were 10m gmL1 and 100m gmL1 for S. aureus and E. coli respectively. The cefaclor reduced gold nanoparticles were further coated onto poly(ethyleneimine) (PEI) modified glass surfaces to obtain antimicrobial coatings suitable for biomedical applications and were tested against E. coli as an exemplar of activity. The antimicrobial coatings were very robust under adverse conditions (pH 3 and 10), inhibited the growth of E. coli on their surfaces, and could be used many times with retained activity. Results from a combined spectroscopic (FTIR) and microscopic study (AFM) suggest that the action of these novel particles is through the combined action of cefaclor inhibiting the synthesis of the peptidoglycan layer and gold nanoparticles generating "holes" in bacterial cell walls thereby increasing the permeability of the cell wall, resulting in the leakage of cell contents and eventually cell death

Silver activation on thin films of Ag-ZrCN coatings for antimicrobial activity

Nowadays, with the increase of elderly population and related health problems, knee and hip joint prosthesis are being widely used worldwide. However, failure of these invasive devices occurs in a high percentage thus demanding the revision of the chirurgical procedure. Within the reasons of failure, microbial infections, either hospital or subsequently-acquired, contribute in high number to the statistics. Staphylococcus epidermidis (S. epidermidis) has emerged as one of the major nosocomial pathogens associated with these infections. Silver has a historic performance in medicine due to its potent antimicrobial activity, with a broad-spectrum on the activity of different types of microorganisms. Consequently, the main goal of this work was to produce Ag-ZrCN coatings with antimicrobial activity, for the surface modification of hip prostheses. Thin films of ZrCN with several silver concentrations were deposited onto stainless steel 316 L, by DC reactive magnetron sputtering, using two targets, Zr and Zr with silver pellets (Zr + Ag target), in an atmosphere containing Ar, C2H2 and N2. The antimicrobial activity of the modified surfaces was tested against S. epidermidis and the influence of an activation step of silver was assessed by testing samples after immersion in a 5 % (w/v) NaClO solution for 5 minutes. The activation procedure revealed to be essential for the antimicrobial activity, as observed by the presence of an inhibition halo on the surface with 11 at. % of Ag. The morphology analysis of the surface before and after the activation procedure revealed differences in silver distribution indicating segregation/diffusion of the metallic element to the films surface. Thus, the results indicate that the silver activation step is responsible for an antimicrobial effect of the coatings, due to silver oxidation and silver ion release.IF acknowledges the financial support of FCT-Fundacao para a Ciencia e a Tecnologia through grant SFRH/BD/71139/2010.This research is partially sponsored by FEDER funds through the program COMPETE-Programa Operacional Factores de Competitividade and by Portuguese national funds through FCT-Fundacao para a Ciencia e a Tecnologia, under the projects ANTIMICROBCOAT-PTDC/CTM/102853/2008 and in the framework of the Strategic Projects PEST-C/FIS/UI607/2011, and PEST-C/EME/UI0285/2011.The authors thank the FCT Strategic Project PEST-OE/EQB/LA0023/2013 and the Project "BioHealth-Biotechnology and Bioengineering approaches to improve health quality", Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, FEDER. The authors also acknowledge the project "Consolidating Research Expertise and Resources on Cellular and Molecular Biotechnology at CEB/IBB", Ref. FCOMP-01-0124-FEDER-027462

Bespoke cationic nano-objects via RAFT aqueous dispersion polymerisation

A range of cationic diblock copolymer nanoparticles are synthesised via polymerisation-induced self-assembly (PISA) using a RAFT aqueous dispersion polymerisation formulation. The cationic character of these nanoparticles can be systematically varied by utilising a binary mixture of two macro-CTAs, namely non-ionic poly(glycerol monomethacrylate) (PGMA) and cationic poly[2-(methacryloyloxy)ethyl]trimethylammonium chloride (PQDMA), with poly(2-hydroxypropyl methacrylate) (PHPMA) being selected as the hydrophobic core-forming block. Thus a series of cationic diblock copolymer nano-objects with the general formula ([1 - n] PGMAx + [n] PQDMAy) - PHPMAz were prepared at 20% w/w solids, where n is the mol fraction of the cationic block and x, y and z are the mean degrees of polymerisation of the non-ionic, cationic and hydrophobic blocks, respectively. These cationic diblock copolymer nanoparticles were analysed in terms of their chemical composition, particle size, morphology and cationic character using 1H NMR spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), and aqueous electrophoresis, respectively. Systematic variation of the above PISA formulation enabled the formation of spheres, worms or vesicles that remain cationic over a wide pH range. However, increasing the cationic character favors the formation of kinetically-trapped spheres, since it leads to more effective steric stabilisation which prevents sphere-sphere fusion. Furthermore, cationic worms form a soft free-standing gel at 25 °C that undergoes reversible degelation on cooling, as indicated by variable temperature oscillatory rheology studies. Finally, the antimicrobial activity of this thermo-responsive cationic worm gel towards the well-known pathogen Staphylococcus aureus is examined via direct contact assays

Antimicrobial polymers as synthetic mimics of host‐defense peptides

Antibiotic‐resistant bacteria ‘superbugs’ are an emerging threat to public health due to the decrease in effective antibiotics as well as the slowed pace of development of new antibiotics to replace those that become ineffective. The need for new antimicrobial agents is a well‐documented issue relating to world health. Tremendous efforts have been given to developing compounds that not only show high efficacy, but also those that are less susceptible to resistance development in the bacteria. However, the development of newer, stronger antibiotics which can overcome these acquired resistances is still a scientific challenge because a new mode of antimicrobial action is likely required. To that end, amphiphilic, cationic polymers have emerged as a promising candidate for further development as an antimicrobial agent with decreased potential for resistance development. These polymers are designed to mimic naturally occurring host‐defense antimicrobial peptides which act on bacterial cell walls or membranes. Antimicrobial‐peptide mimetic polymers display antibacterial activity against a broad spectrum of bacteria including drug‐resistant strains and are less susceptible to resistance development in bacteria. These polymers also showed selective activity to bacteria over mammalian cells. Antimicrobial polymers provide a new molecular framework for chemical modification and adaptation to tune their biological functions. The peptide‐mimetic design of antimicrobial polymers will be versatile, generating a new generation of antibiotics toward implementation of polymers in biomedical applications. WIREs Nanomed Nanobiotechnol 2013, 5:49–66. doi: 10.1002/wnan.1199 Conflict of interest: K. K. is a coinventor on a patent application filed by the University of Pennsylvania covering ‘Antimicrobial Copolymers and Uses Thereof’. The patent application has been licensed to PolyMedix Inc. (Radnor, PA). PolyMedix did not play a role in the design and conduct of this study; in the collection, analysis, or interpretation of the data; or in the preparation, review, or approval of the article. For further resources related to this article, please visit the WIREs website .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94848/1/1199_ftp.pd

Antimicrobial synergy of cationic grafted poly(para-phenylene ethynylene) and poly(para-phenylene vinylene) compounds with UV or metal ions against Enterococcus faecium

The rise in multidrug resistant bacteria is an area of growing concern and it is essential to identify new biocidal agents. Cationic grafted compounds were investigated for their antimicrobial properties using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests. Synergy testing was carried out using the compounds in the presence of ultraviolet (UV). Fractional inhibitory concentration (FIC) and fractional bactericidal concentration (FBC) tests were carried out using the cationic molecules in conjunction with metal ion solutions of gold, silver, palladium, platinum, rhodium, titanium, tin, vanadium and molybdenum. Individually, the cationic compounds containing quaternary amines, polyphenylene vinylene (PPV) with long polyacrylate grafts (PPV-g-PMETAC (HMw)), polyphenylene ethylene (PPE) with long polyacrylate grafts (PPE-g-PMETAC (HMw)), polyphenylene vinylene (PPV) with short polyacrylate grafts (PPV-g-PMETAC (LMw)) and polyphenylene ethylene (PPE) with short polyacrylate grafts (PPE-gPMETAC (LMw)) were effective against Enterococcus faecium. The most successful compound under UV was PPV-g-PMETAC (HMw). Following the FICs, palladium and rhodium ion solutions caused a synergistic reaction with all four tested compounds. The presence of conjugated bonds in the cationic molecules increased its antimicrobial activity. These results suggest that the chemical backbone of the compounds, alongside the chain lengths and chain attachment affect the antimicrobial efficacy of a compound. These factors should be taken into consideration when formulating new biocidal combinations

Study of Mobile Payment Services in India : Distribution of the roles, responsibilities and attitudes amongst actors of the payment systems

Information technology and payment systems have witnessed the introduction, acceptance and wide scale deployment of electronic payment systems. The payment system ecosystem has now witnessed the introduction of mobile payment systems and their associated services. Major actors involved in mobile payment systems include telecom operators, banks, merchants and consumers. They need to aggregate their resources and develop a coherent ecosystem which would help the individual actors while also benefiting the overall mobile payment ecosystem. Financial institutions and mobile carriers are becoming increasingly interested and have started collaborating in order to provide mobile payment capabilities which would pave the way for the migration of payment systems from card-based to phone-based. In a developing country like India, mobile payment systems have experienced rapid growth, deployment and acceptance in a very short span of time. However, these systems are still far from mature and need to be customized and refined further in order to replace or equal the deployment and acceptance of electronic payment systems. Mobile payment services are primarily centered on the unbanked population but also consider the existing population with active bank accounts especially in developing countries.   The thesis describes the rapid growth and development of payment systems in India and how there has been a slow shift from e-payment systems to m-payment systems. The key mobile payment systems described in the thesis includes but not limited to, the Nokia money, and Airtel money. The key findings of the thesis have been supplemented with SWOT analysis, ARA model analysis and Ansoff matrix models of the mobile payment systems in the Indian market. The business models described in the thesis have been analyzed by considering a few key factors and analysis results depicted that the biggest challenge of deploying mobile payment systems is initiated by uncertainties in the environment which result in lack of Acceptance Network, Interoperability and Accessibility for everyone in society (Including educated and un-educated).