Development and characterization of a novel, antimicrobial, sterile hydrogel dressing for burn wounds : single-step production with gamma irradiation creates silver nanoparticles and radical polymerization

Patients with burn wounds are susceptible to wound infection and sepsis. This research introduces a novel burn wound dressing that contains silver nanoparticles (SNPs) to treat infection in a 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS-Na(+) ) hydrogel. Silver nitrate was dissolved in AMPS-Na(+) solution and then exposed to gamma irradiation to form SNP-infused hydrogels. The gamma irradiation results in a cross-linked polymeric network of sterile hydrogel dressing and a reduction of silver ions to form SNPs infused in the hydrogel in a one-step process. About 80% of the total silver was released from the hydrogels after 72 h immersion in simulated body fluid solution; therefore, they could be used on wounds for up to 3 days. All the hydrogels were found to be nontoxic to normal human dermal fibroblast cells. The silver-loaded hydrogels had good inhibitory action against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. Results from a pilot study on a porcine burn model showed that the 5-mM silver hydrogel was efficient at preventing bacterial colonization of wounds, and the results were comparable to the commercially available silver dressings (Acticoat(TM) , PolyMem Silver(®) ). These results support its use as a potential burn wound dressing.

Utilizing reactive capability of PV inverters and battery systems to improve voltage profile of a residential distribution feeder

Significant increase in installation of rooftop Photovoltaic (PV) in the Low-Voltage (LV) residential distribution network has resulted in over voltage problems. Moreover, increasing peak demand creates voltage dip problems and make voltage profile even worse. Utilizing the reactive power capability of PV inverter (RCPVI) can improve the voltage profile to some extent. Resistive caharcteristic (higher R/X ratio) limits the effectiveness of reactive power to provide voltage support in distribution network. Battery Energy Storage (BES), whereas, can store the excess PV generation during high solar insolation time and supply the stored energy back to the grid during peak demand. A coordinated algorithm is developed in this paper to use the reactive capability of PV inverter and BES with droop control. Proposed algorithm is capable to cater the severe voltage violation problem using RCPVI and BES. A signal flow is also mentioned in this research work to ensure smooth communication between all the equipments. Finally the developed algorithm is validated in a test distribution network.

The harnessing of peptide-monolith constructs for single step plasmid DNA purification

The availability of synthetic peptides has paved the way for their use in tailor-made interactions with biomolecules. In this study, a 16mer LacI-based peptide was used as an affinity ligand to examine the scale up feasibility for plasmid DNA purification. First, the peptide was designed and characterized for the affinity purification of lacO containing plasmid DNA, to be employed as a high affinity ligand for the potential capturing of plasmid DNA in a single unit operation. It was found there were no discernible interactions with a control plasmid that did not encode the lacO nucleotide sequence. The dissociation equilibrium constant of the binding between the 16mer peptide and target pUC19 was 5.0 ± 0.5 × 10-8 M as assessed by surface plasmon resonance. This selectivity and moderated affinity indicate that the 16mer is suitable for the adsorption and chromatographic purification of plasmid DNA. The suitability of this peptide was then evaluated using a chromatography system with the 16mer peptide immobilized to a customized monolith to purify plasmid DNA, obtaining preferential purification of supercoiled pUC19. The results demonstrate the applicability of peptide-monolith supports to scale up the purification process for plasmid DNA using designed ligands via a biomimetic approach.

Single step purification of plasmid DNA using peptide ligand affinity chromatography

Single step affinity chromatography was employed for the purification of plasmid DNA (pDNA), thus eliminating several steps compared with current commercial purification methods for pDNA. Significant reduction in pDNA production time and cost was obtained. This chromatographic operation employed a peptide-monolith construct to isolate pDNA from Escherichia coli (E. coli) impurities present in a clarified lysate feedstock. Mild conditions were applied to avoid any degradation of pDNA. The effect of some important parameters on pDNA yield was also evaluated with the aim of optimising the affinity purification of pDNA. The results demonstrate that 81% of pDNA was recovered and contaminating gDNA, RNA and protein were removed below detectable levels. © 2008 Elsevier B.V. All rights reserved.

Endotoxin removal : a critical step in vaccine production

A major drawback to the immunological potency of conventional vaccines, resulting in reduced level of immune responses, tissue injury, shock and high cytotoxicity, thus making their applications contraindicated in immunodeficiency diseases, is the presence of high contaminant concentrations in vaccine titers. Vaccine contamination arises from the simultaneous occurrence of competitive pathways resulting in the formation of other bio-products during cellular metabolism aside the pathways necessary for the production of vaccine molecules. One of such vaccine contaminating molecules is endotoxins which are mainly lipopolysaccharides (LPS) complexes found in the membrane of bacterial cell wall. The structural dynamics of these molecules make their removal from vaccine titers problematic, thus making vaccine endotoxin removal a major research endeavour. This presentation will discuss a novel technique for reducing the endotoxin level of vaccines. The technique commences with the disentanglement of endotoxin-vaccine molecular bonding and then capturing the vaccine molecules on an affinity monolith to separate the vaccine molecules from the endotoxins.

Segmenting Australian high school students : two-step cluster analysis preliminary results

A one size fits all approach dominates alcohol programs in school settings (Botvin et al., 2007), which may limit program effectiveness (Snyder et al., 2004). Programs tailored to the meet the needs and wants of adolescent groups may be more effective. Limited attention has been directed towards employing a full segmentation process. Where segmentation has been examined, the focus has remained on socio-demographic characteristics and more recently psychographic variables (Mathijssen et al., 2012). The current study aimed to identify whether the addition of behaviour could be used to identify segments. Variables included attitudes towards binge drinking (α = 0.86), behavioral intentions’ (α = 0.97), perceived behavioral control (PBC), injunctive norms (α = 0.94); descriptive norms (α = 0.87), knowledge and reported behaviour. Data was collected from five schools, n = 625 (32.96% girls). Two-Step cluster analysis produced a sample (n = 625) with a silhouette measure of cohesion and separation of 0.4. The intention measure and whether students reported previously consuming alcohol were the most distinguishing characteristics - predictor importance scores of (1.0). A four segment solution emerged. The first segment (“Male abstainers” – 37.2%) featured the highest knowledge score (M: 5.9) along with the lowest-risk drinking attitudes and intentions to drink excessively. Segment 2 (“At risk drinkers” - 11.2%) were characterised by their high-risk attitudes and high-risk drinking intentions. Injunctive (M: 4.1) and descriptive norms (M: 4.9) may indicate a social environment where drinking is the norm. Segment 3 (”Female abstainers” – 25.9%) represents young girls, who have the lowest-risk attitudes and low intentions to drink excessively. The fourth and final segment (boys = 67.4%) (“Moderate drinkers” – 25.7%) all report previously drinking alcohol yet their attitudes and intentions towards excessive alcohol consumption are lower than other segments. Segmentation focuses on identifying groups of individuals who feature similar characteristics. The current study illustrates the importance of including reported behaviour in addition to psychographic and demographic characteristics to identify unique groups to inform intervention planning and design. Key messages The principle of segmentation has received limited attention in the context of school-based alcohol education programs. This research identified four segments amongst 14-16 year high school students, each of which can be targeted with a unique, tailored program to meet the needs and wants of the target audience.

Reactive reaching and grasping on a humanoid: Towards closing the action-perception loop on the iCub

We propose a system incorporating a tight integration between computer vision and robot control modules on a complex, high-DOF humanoid robot. Its functionality is showcased by having our iCub humanoid robot pick-up objects from a table in front of it. An important feature is that the system can avoid obstacles - other objects detected in the visual stream - while reaching for the intended target object. Our integration also allows for non-static environments, i.e. the reaching is adapted on-the-fly from the visual feedback received, e.g. when an obstacle is moved into the trajectory. Furthermore we show that this system can be used both in autonomous and tele-operation scenarios.

One step closer into the design of fall protective device for individuals fitted with a bone-anchored prosthesis

The consequences of falls are often dreadful for individuals with lower limb amputation using bone-anchored prosthesis.[1-5] Typically, the impact on the fixation is responsible for bending the intercutaneous piece that could lead to a complete breakage over time. .[3, 5-8] The surgical replacement of this piece is possible but complex and expensive. Clearly, there is a need for solid data enabling an evidence-based design of protective devices limiting impact forces and torsion applied during a fall. The impact on the fixation during an actual fall is obviously difficult to record during a scientific experiment.[6, 8-13] Consequently, Schwartze and colleagues opted for one of the next best options science has to offer: simulation with an able-bodied participant. They recorded body movements and knee impacts on the floor while mimicking several plausible falling scenarios. Then, they calculated the forces and moments that would be applied at four levels along the femur corresponding to amputation heights.[6, 8-11, 14-25] The overall forces applied during the falls were similar regardless of the amputation height indicating that the impact forces were simply translated along the femur. As expected, they showed that overall moments generally increased with amputation height due to changes in lever arm. This work demonstrates that devices preventing only against force overload do not require considering amputation height while those protecting against bending moments should. Another significant contribution is to provide, for the time, the magnitude of the impact load during different falls. This loading range is crucial to the overall design and, more precisely, the triggering threshold of protective devices. Unfortunately, the analysis of only a single able-bodied participant replicating falls limits greatly the generalisation of the findings. Nonetheless, this case study is an important milestone contributing to a better understanding of load impact during a fall. This new knowledge will improve the treatment, the safe ambulation and, ultimately, the quality of life of individuals fitted with bone-anchored prosthesis.