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Yielding and fracturing of concentrated emulsions in narrow gaps
No full textWe used rheology and confocal microscopy techniques to characterise the flow of emulsions as the droplets were confined by increasing the drop volume fraction and reducing the distance between the shearing surfaces. Slip was minimised by matching the density of the oil and water phases. Attractive interactions between the drops caused them to flocculate. The contribution of the emulsion microstructure to its shear response becomes significant when the oil drop flocs almost span the distance between the surfaces. We found that confining the flow of droplet flocs causes a transition from a fluid phase with shear thinning flow behaviour into a jammed, solid-like material. The large deformations caused by flow at the maximum drop packing fraction induce droplet coalescence within highly localised regions of the emulsion.
Applications of modern sensors and wireless technology in effective wound management
No full textThe management of chronic wounds has emerged as a major health care challenge during the 21st century consuming, significant portions of health care budgets. Chronic wounds such as diabetic foot ulcers, leg ulcers, and pressure sores have a significant negative impact on the quality of life of affected individuals. Covering wounds with suitable dressings facilitates the healing process and is common practice in wound management plans. However, standard dressings do not provide insights into the status of the wound underneath. Parameters such as moisture, pressure, temperature and pH inside the dressings are indicative of the healing rate, infection, and wound healing phase. But owing to the lack of information available from within the dressings, these are often changed to inspect the wound, disturbing the normal healing process of wounds in addition to causing pain to the patient. Sensors embedded in the dressing would provide clinicians and nurses with important information that would aid in wound care decision making, improve patient comfort, and reduce the frequency of dressing changes. The potential benefits of this enabling technology would be seen in terms of a reduction in hospitalization time and health care cost. Modern sensing technology along with wireless radio frequency communication technology is poised to make significant advances in wound management. This review discusses issues related to the design and implementation of sensor technology and telemetry systems both incorporated in wound dressings to devise an automated wound monitoring technology, and also surveys the literature available on current sensor and wireless telemetry systems.
Rapid high-throughput analysis of ochratoxin A by the self-assembly of DNAzyme-aptamer conjugates in wine
No full textWe report a new label-free colorimetric aptasensor based on DNAzyme–aptamer conjugate for rapid and high-throughput detection of Ochratoxin A (OTA, a possible human carcinogen, group 2B) in wine. Two oligonucleotides were designed for this detection. One is N1 for biorecognition, which includes two adjacent sequences: the OTA-specific aptamer sequence and the horseradish peroxidase (HRP)-mimicking DNAzyme sequence. The other is a blocking DNA (B2), which is partially complementary to a part of the OTA aptamer and partially complementary to a part of the DNAzyme. The existence of OTA reduces the hybridization between N1 and B2. Thus, the activity of the non-hybridized DNAzyme is linearly correlated with the concentration of OTA up to 30 nM with a limit of detection of 4 nM (3σ). Meanwhile, a double liquid–liquid extraction (LLE) method is accordingly developed to purify OTA from wine. Compared with the existing HPLC-FD or immunoassay methods, the proposed strategy presents the most appropriate balance between accuracy and facility, resulting in a considerable improvement of real-time quality control, and thereby, preventing chronic poisoning caused by OTA contained red wine.
Application of MicroResp™ for soil ecotoxicology
No full textMicroResp™ is a miniaturised method for measuring substrate induced respiration (SIR) in soil. We modified the MicroResp™ method to develop a rapid tool for quantifying the ecotoxicological impact of contaminants. The method is based on reduction in SIR across a gradient of contaminant, allowing for determination of doseeresponse curves EC-values. Contaminants are mixed into soil samples at a range of concentrations; each sample is then dispensed into a column of eight wells in 96 well format (deep) plates. Moisture and glucose are added to the samples at levels to provide maximum response. Released CO2 from the soils is then measured using colorimetric gel-traps, following the standard MicroResp™ methodology. Examination revealed that this method works over a range of soil types and is insensitive to minor variations in assay length (2-7 h), alteration of moisture content (± 20 mL from optimum), and soil storage conditions (4° C versus fresh).
Enzyme responsive hyaluronic acid nanocapsules containing polyhexanide and their exposure to bacteria to prevent infection
No full textAntibacterial nanodevices could bring coatings of plastic materials and wound dressings a big step forward if the release of the antibacterial agents could be triggered by the presence of the bacteria themselves. Here, we show that novel hyaluronic acid (HA)-based nanocapsules containing the antimicrobial agent polyhexanide are specifically cleaved in the presence of hyaluronidase, a factor of pathogenicity and invasion for bacteria like Staphylococcus aureus and Escherichia coli. This resulted in an efficient killing of the pathogenic bacteria by the antimicrobial agent. The formation of different polymeric nanocapsules was achieved through a polyaddition reaction in inverse miniemulsion. After the synthesis, the nanocapsules were transferred to an aqueous medium and investigated in terms of size, size distribution, functionality, and morphology using dynamic light scattering, zeta potential measurements and scanning electron microscopy. The enzyme triggered release of a model dye and the antimicrobial polyhexanide was monitored using fluorescence and UV spectroscopy. The stability of the nanocapsules in several biological media was tested and the interaction of nanocapsules with human serum protein was studied using isothermal titration calorimetry. The antibacterial effectiveness is demonstrated by determination of the antibacterial activity and determination of the minimal bactericidal concentration (MBC).
Characterization and predicting DOM treatability by enhanced coagulation
No full textThe dissolved organic matter (DOM) plays significant role in water safety due to not only the natural occurrence but also man-induced pollution. To characterize and predict DOM treatability becomes therefore a very important and hot topic. In this paper, enhanced coagulation by four typical coagulants (FeCl3, Al2(SO4)3, polyaluminum chloride (PAC) and high performance polyaluminum chloride (HPAC)) without pH control was characterized using the chemical fractionation (resin adsorption, RA) and physical fractionation (high performance size exclusion chromatography (HPSEC) combined with peak fitting technique). The results show that the DOM removal can be separated into two stages, rapid removal and continual slow removal. The PAC exhibits efficient removal in the rapid part while the traditional salts are more efficient in the latter part. It is also very important for pH control to improve DOM removal by the traditional coagulants. DOM treatability per unit dosage (1 × 10−4 mol/l) for the four coagulants was then calculated in the order of HPAC (26.0%) > PAC (17.3%) > FeCl3 (14.3%) > Al2(SO4)3 (12.0%). Two sets of DOM treatability models, i.e. removal efficiency, for enhanced coagulation of the four coagulants were developed by combining the chemical and physical DOM fractions based on the quantitative analysis of the removal state of raw water. The two sets of models could be transformed to each other. The composition of the removable DOM by enhanced coagulation of the four coagulants was revealed and validated using 29 raw waters (in 13 source waters in three seasons), and as a result the low deviation indicated that the predicted data matched well with the actual data. It provided the possibility for the application in practical operation of water plant.
Chemometric approaches to data assessment for a long-term case study of MIEX pretreatment performance
No full textA specifically designed pilot plant facility located at the Mount Pleasant Water Treatment Plant in South Australia was used to investigate the efficiencies of several drinking water treatment processes, including (1) magnetic ion exchange (MIEX) as a pretreatment followed by conventional coagulation treatment, (2) conventional coagulation at pilot the plant alone, (3) MIEX followed by microfiltration (MF), and (4) MF alone. Dissolved organic matter (DOM) removal efficiency of the treatment processes and more importantly the treated water quality was assessed using dissolved organic carbon (DOC) measurement and together with the changes in the chromophoric organics character based on their molecular weight profiles determined by high-performance size exclusion chromatography (HPSEC) were also reported. Cluster analyses (CAs) were performed using the HPSEC peak area (after separated by peak fitting), and supported by DOC, UV absorbance at 254 nm, and SUVA in order to compare treatment efficiencies of these technologies. It was a novel way of applying CA as a data mining tool to interpret and assess DOM removal results. From the results of these CA, it was found that the MIEX process provided consistent treatment performance and highest removal of DOM, as well as removal of a broad range of molecular weight organics. In comparison coagulation with alum tended to remove the high molecular weight (>1000 Da) compounds. This statistical approach provided improved understanding of the performances of the treatment processes, investigated at a molecular level, for the removal of DOM.
Limb-specific autonomic dysfunction in complex regional pain syndrome modulated by wearing prism glasses
No full textIn unilateral upper-limb complex regional pain syndrome (CRPS), the temperature of the hands is modulated by where the arms are located relative to the body midline. We hypothesized that this effect depends on the perceived location of the hands, not on their actual location, nor on their anatomical alignment. In 2 separate cross-sectional randomized experiments, 10 (6 female) unilateral CRPS patients wore prism glasses that laterally shifted the visual field by 20 . Skin temperature was measured before and after 9-minute periods in which the position of one hand was changed. Placing the affected hand on the healthy side of the body midline increased its temperature (D C = +0.47 ± 0.14 C), but not if prism glasses made the hand appear to be on the body midline (D C = +0.07 ± 0.06 C). Similarly, when prism glasses made the affected hand appear to be on the healthy side of the body midline, even though it was not, the affected hand warmed up (D C = +0.28 ± 0.14 C). When prism glasses made the healthy hand appear to be on the affected side of the body midline, even though it was not, the healthy hand cooled down (D C = 0.30 ± 0.15 C). Friedman’s analysis of variance and Wilcoxon pairs tests upheld the results (P < 0.01 for all). We conclude that, in CRPS, cortical mechanisms responsible for encoding the perceived location of the limbs in space modulate the temperature of the hands.
Penetration of nanoparticles into human skin
No full textExposure of human skin to nanoparticles (NPs) is increasing with the development of nanotechnology and new applications of NPs in medicine. Safety concerns have sparked debate on the capacity of NPs to penetrate through skin and enter into the body. This article attempts to summarize the recent evidence on whether NPs penetrate human skin and the factors that may affect the penetration. Skin structure and penetration mechanisms are reviewed to provide background information. Size, shape, formulation, surface properties and application methods and their effects on skin penetration are specifically discussed. Finally, the relationship between skin penetration and nanotoxicity is reviewed to further emphasise the importance of the research in this area.
A simple mechanism for mid-crustal shear zones to record surface-derived fluid signatures
No full textIon microprobe analyses of garnet porphyroblasts from three separate splays of the mid-crustal Walter-Outalpa shear zone, Curnamona Province, South Australia, indicate homogeneous δ18O values of <3‰. Integrated Lu-Hf geochronology and electron microprobe compositional mapping demonstrate that closed-system growth of these isotopically light garnets initiated as early as 531 Ma, prior to peak metamorphism and deformation during the Delamerian Orogeny (514–490 Ma). We attribute this to the prograde burial and dehydration of altered fault panels under thick sedimentary sequences during pre-orogenic basin formation. Contrary to established fluid transport models, surficial fluid signatures were not imposed at depth by large fluxes of downward-penetrating fluids, but rather by the exposure and meteoric alteration of fault rocks that were subsequently buried and reactivated as ductile shear zones. The existence of low δ18O values in deeply exhumed shear zones may therefore be indicative of fault structures that have a prior history of surface exposure, weathering, burial and re-exposure.