Effect of ciprofloxacin incorporation in PVA and PVA bioactive glass composite scaffolds

International audienceScaffolds are implants used to deliver cells, drugs, and genes into the body in a local controlled release pattern which offers many advantages over systematic drug delivery. Composite scaffolds of polyvinyl alcohol (PVA) and quaternary bioactive glass (46S6 system) with different ratios of glass contents were prepared by the lyophilisation technique. The broad spectrum antibiotic ciprofloxacin (Cip) was impregnated to the scaffold during the fabrication in a concentration of 5, 10 and 20%. Biodegradation rate and in-vitro mineralization of the prepared scaffolds were performed by soaking the scaffolds in simulated body fluid (SBF). Phase identification, microstructure, porosity, bioactivity, mechanical properties and drug release pattern in PBS were characterized by XRD, SEM coupled with EDS, Hg-porosimeter, inductively coupled plasma-optical emission spectroscopy (ICP-OES), universal testing machine, fourier transform infrared (FTIR) and UV-spectrophotometer, respectively. A porous scaffold has been obtained with porosity up to 85%. By increasing the glass contents in the prepared scaffold the porosity and the degradation rate decrease however, the compressive strength was enhanced. A sustained drug release pattern was observed with a quasi-Fickian diffusion mechanism. The formulated ciprofloxacin loaded porous polyvinyl alcohol scaffold gave an acceptable physicochemical properties and was able to deliver the drug in a prolonged release pattern which offers a distinguish treatment for osteomylitis as well as local antibacterial effect

Comparative Study of Nanobioactive Glass Quaternary System 46S6

International audienceDifferent bioactive glass systems have been prepared by sol-gel. However, the production of Na2O-containing bioactive glasses by sol-gel methods has proved to be difficult as the sodium nitrate used in the preparation could be lost from the glass structure during filtration and washing. The aim of this study was to prepare the quaternary system 46S6 of bioactive glass by modified sol-gel techniques with a decrease in the time of gelation. In addition, compare the behaviour of the prepared sol-gel bioactive glass system by its corresponding prepared by melting. The obtained glasses were characterized by using several physicochemical techniques; XRD, FTIR, TEM and SEM beside the effect of the glass particles on the viability of osteoblast like cells (Saos-2). Results show that nanopowders 40-60 nm of 46S6 glass system had been prepared by modified sol-gel (acid-base reaction) method at 600°C in just three days at 600°C. Cell viability by MTT assay confirmed the effectiveness of the prepared nanobioactive glass

Evaluating the immediate and longer term impact of a refusal conversion strategy in a large scale longitudinal study

Refusal conversion is one of the fieldwork strategies commonly used to minimise non-response in surveys. There is, however, relatively little evidence about the effectiveness of this strategy, particularly for face-to-face longitudinal surveys. Moreover, much of the existing evidence is based on observational studies. This paper evaluates the effectiveness of a fieldwork strategy – intensive re-issuing - to convert refusals using evidence from an intervention on a random sub-sample of refusals implemented in wave four of a large scale longitudinal study in the UK: the Millennium Cohort Study. We show that intensive re-issuing is an effective way of reducing the refusal rate. We also show that refusal conversion led to a modest reduction in non-response bias in the survey estimates for several key variables. The longer term impact of refusal conversion is also a key concern in longitudinal surveys. We demonstrate that, although the majority of converted refusals go on to participate in the subsequent wave of the study, there is no overall effect of intensive re-issuing on sample size at this wave

Small size boundary effects on two-pion interferometry

The Bose-Einstein correlations of two identically charged pions are derived when these particles, the most abundantly produced in relativistic heavy ion collisions, are confined in finite volumes. Boundary effects on single pion spectrum are also studied. Numerical results emphasize that conventional formulation usually adopted to describe two-pion interferometry should not be used when the source size is small, since this is the most sensitive case to boundary effects. Specific examples are considered for better illustration.Comment: more discussion on Figure4 and diffuse boundar

Environmental life cycle assessment and techno-economic analysis of triboelectric nanogenerators

As the world economy grows and industrialization of the developing countries increases, the demand for energy continues to rise. Triboelectric nanogenerators (TENGs) have been touted as having great potential for low-carbon, non-fossil fuel energy generation. Mechanical energies from, amongst others, body motion, vibration, wind and waves are captured and converted by TENGs to harvest electricity, thereby minimizing global fossil fuel consumption. However, only by ascertaining performance efficiency along with low material and manufacturing costs as well as a favorable environmental profile in comparison with other energy harvesting technologies, can the true potential of TENGs be established. This paper presents a detailed techno-economic lifecycle assessment of two representative examples of TENG modules, one with a high performance efficiency (Module A) and the other with a lower efficiency (Module B) both fabricated using low-cost materials. The results are discussed across a number of sustainability metrics in the context of other energy harvesting technologies, notably photovoltaics. Module A possesses a better environmental profile, lower cost of production, lower CO2 emissions and shorter energy payback period (EPBP) compared to Module B. However, the environmental profile of Module B is slightly degraded due to the higher content of acrylic in its architecture and higher electrical energy consumption during fabrication. The end of life scenario of acrylic is environmentally viable given its recyclability and reuse potential and it does not generate toxic gases that are harmful to humans and the environment during combustion processes due to its stability during exposure to ultraviolet radiation. Despite the adoption of a less optimum laboratory manufacturing route, TENG modules generally have a better environmental profile than commercialized Si based and organic solar cells, but Module B has a slightly higher energy payback period than PV technology based on perovskite-structured methyl ammonium lead iodide. Overall, we recommend that future research into TENGs should focus on improving system performance, material optimization and more importantly improving their lifespan to realize their full potential

Géométrie de l'aquifère du Haouz oriental et Tassaout amont, Maroc occidental: approche géophysique et hydrogéologique

The aim of the present study is to improve the knowledge of the geometry and hydrogeology of the eastern Haouz aquifer and part of the Upper Tassaout aquifer, using the analysis and interpretation of boreholes, gravimetric analysis, seismic reflection and piezometric data. The examination of the gravity data shows that the Bouguer anomaly map is affected by a regional gradient increasing from the southeast to northwest. This gradient was determined and subtracted from the original data, to provide a residual gravity map which shows clearly highlighted anomalies. These anomalies generally reflect outcrop areas of the basement and the variation in thickness of the sedimentary cover across the study area. The seismic reflection profile confirms the gravity results, and shows that the region is formed by a horst which corresponds to the exposed bedrock of Jebilets in the north of Haouz basin, and a subsidence area where coverage is widespread in the south of the plain of Haouz. In this area, the large thickness of the cover allows the accumulation of water and provides the recharge of the groundwater reservoir. The rise of the basement in the north of the Haouz basin imposes a dividing line of two groundwater flow direction

Extremely large extinction efficiency and field enhancement in terahertz resonant dipole nanoantennas

The distinctive ability of nanometallic structures to manipulate light at the nanoscale has recently promoted their use for a spectacular set of applications in a wide range of areas of research including artificial optical materials, nano-imaging, biosensing, and nonlinear optics. Here we transfer this concept to the terahertz spectral region, demonstrating a metal nanostructure in shape of a dipole nanoantenna, which can efficiently resonate at terahertz frequencies, showing an effective cross section >100 times larger than its geometrical area, and a field enhancement factor of ~280, confined on a lateral section of ~λ/1,000. These results lead to immediate applications in terahertz artificial materials exhibiting giant dichroism, suggest the use of dipole nanoantennas in nanostructure-based terahertz metamaterials, and pave the way for nanoantenna-enhanced terahertz few-molecule spectroscopy and localized terahertz nonlinear optics

Viral population estimation using pyrosequencing

The diversity of virus populations within single infected hosts presents a major difficulty for the natural immune response as well as for vaccine design and antiviral drug therapy. Recently developed pyrophosphate based sequencing technologies (pyrosequencing) can be used for quantifying this diversity by ultra-deep sequencing of virus samples. We present computational methods for the analysis of such sequence data and apply these techniques to pyrosequencing data obtained from HIV populations within patients harboring drug resistant virus strains. Our main result is the estimation of the population structure of the sample from the pyrosequencing reads. This inference is based on a statistical approach to error correction, followed by a combinatorial algorithm for constructing a minimal set of haplotypes that explain the data. Using this set of explaining haplotypes, we apply a statistical model to infer the frequencies of the haplotypes in the population via an EM algorithm. We demonstrate that pyrosequencing reads allow for effective population reconstruction by extensive simulations and by comparison to 165 sequences obtained directly from clonal sequencing of four independent, diverse HIV populations. Thus, pyrosequencing can be used for cost-effective estimation of the structure of virus populations, promising new insights into viral evolutionary dynamics and disease control strategies.Comment: 23 pages, 13 figure

Cyber security fear appeals:unexpectedly complicated

Cyber security researchers are starting to experiment with fear appeals, with a wide variety of designs and reported efficaciousness. This makes it hard to derive recommendations for designing and deploying these interventions. We thus reviewed the wider fear appeal literature to arrive at a set of guidelines to assist cyber security researchers. Our review revealed a degree of dissent about whether or not fear appeals are indeed helpful and advisable. Our review also revealed a wide range of fear appeal experimental designs, in both cyber and other domains, which confirms the need for some standardized guidelines to inform practice in this respect. We propose a protocol for carrying out fear appeal experiments, and we review a sample of cyber security fear appeal studies, via this lens, to provide a snapshot of the current state of play. We hope the proposed experimental protocol will prove helpful to those who wish to engage in future cyber security fear appeal research