Search

David Marks’ previous book about the paranormal (Marks, 2000) and other earlier writings established his reputation as a firm skeptic. He wrote the current book in order to learn about new developments in paranormal research during the past 20 years. The overall conclusion in this book is that Marks now believes that spontaneous paranormal phenomena may occur, but psi is a spontaneous process that cannot be controlled and demonstrated in laboratory experiments. His belief that instances of spontaneous psi may occur is based largely on a personal experience of synchronicity that had layers of meaning for him. The experience is described and evaluated in chapter four. He rates the probability as 75% that the experience had a paranormal component.

The lessons and recommendations described here were developed from conducting a research audit of the Transparent Psi Project (TPP). The TPP was intended as a potential model and learning experience for optimal research practices. The topics discussed here are among the potential lessons from the TPP. The recommendations are: (1) Validation of data collection software is essential. (2) Evaluation of power or operating characteristics (inferential errors) is essential, including for sequential Bayesian analyses. (3) An online repository copy of data is very valuable, but easy-to-use, reliable, secure processes remain to be developed. (4) A good research audit is much more extensive than current peer review for publication, including Registered Reports. (5) Quality control (QC) comes before auditing. (6) Good research practice guidelines and/or standard operating procedures (SOPs) for general use would be very valuable for confirmatory psychological research. (7) It is time to implement routine measures to prevent experimenter fraud. (8) Git appears to be not optimal for software tracking to prevent programming fraud.

Information processing underlies all life and is a defining characteristic of life. Concepts of information are also increasingly proposed as underlying or having a role in the mysteries of quantum physics. However, scientific progress is hindered by different concepts, terminology, and assumptions about information in different branches of science and technology. The purpose of this paper is to identify and explore fundamental concepts of information that are applicable throughout the wide spectrum of uses of the term. The terms symbolic information and physical information are used here to distinguish between two fundamentally different concepts of information. Symbolic information is based on symbols created by living entities as part of processes for perception, memory, communication, purposeful action, or planning. Symbolic information has three components: symbolic representation, media, and interpretational infrastructure. Symbolic information is the mechanism for living entities to generate variability, adaptability, and creativity from the fixed, relatively deterministic forces of physics. Symbolic information processing is the fundamental reason that living systems have properties that are categorically different from the properties of nonliving matter. Living systems have layer upon layer of interacting symbolic information processing, from reproduction to imagination, creativity, and culture. The term physical information is used here for the concept that any physical non-uniformity, difference, or distinction is information. Physical information is a descriptive property of the distribution of matter and energy. Physical information is conceptually related to entropy in physics and does not consider whether different physical states have meaning for living beings or were created by living entities for use as symbols. The failure to distinguish between symbolic information and physical information often results in ambiguous, misleading concepts that (a) imply nonliving processes have properties of life, (b) undervalue the essential role of interpretation for symbolic information, and (c) do not recognize the creative potential of symbolic information processing. If the term information is proposed as an explanatory factor in physics, any implications that nonliving processes encode or interpret information must be carefully justified in context of the differences between symbolic and physical information.

The addition of nanoclay within polymer matrix is anticipate to enhance the properties of the polymer system. Nonetheless, one of the key elements in property enhancements of a polymer nanocomposites is the surface modifications of the nanoclay. This is due to the affinity between polymer matrix and nanoclay is of important factors should be considered. In this study, amorphous polyamide were melt blended with different nanoclay grades with different surface modifications in order to evaluate the best clay grade for the polymer system. The thermal analysis carried out on the amorphous polyamide nanocomposites were carried out by means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) whereas the mechanical properties were investigated using tensile testing. It was observed that there were changes in the glass transition temperature (Tg) of the nanocomposites due to clay additions. Further, the storage modulus was found to increase as a result of nanoclay incorporation. The type of clay grades significantly affects the mechanical properties of the amorphous polyamide nanocomposites.

The problem of dispersion of nano-additives in thermoplastic elastomers using continuous processing techniques still prevails in scientific and engineering applications. To address this, supercritical fluid (SCF) assisted extrusion was utilised to develop elastic, isotropic and electrically superior materials, which contain elastomeric microphases of Poly(styrene-ethylene-butylene-styrene [SEBS] with homogeneously dispersed conductive nano-additives of carbon black [CB]. SEBS-SCF/CB 5 wt% extrudates showed 46% and 14% higher storage modulus compared to their counterparts in transverse and longitudinal direction respectively. Similarly, piezo-resistive properties of SEBS-SCF/CB composites were found to have a superior strain gauge factor with linear decrease in conductivity with increasing strain, compared to nonlinear increase/decrease in piezoresistive behaviour of SEBS/CB composites. Piezo-resistivity of SEBS-SCF/CB 5 wt% nanocomposites were found to be highly sensitive in both bending (3.6% change in resistance per degree for 1.7 cm thick sample) and tensile strain conditions (gauge factor ca. 9) for smart applications.

Graphical abstract, Engineering of self-disinfecting surfaces to constrain the spread of SARS-CoV-2 is a challenging task for the scientific community, because the human coronavirus spreads through respiratory droplets. Titania (TiO2) nanocomposite antimicrobial coatings is one of the ideal remedies to disinfect pathogens (virus, bacteria, fungi) from common surfaces under light illumination. The photocatalytic disinfection efficiency of recent TiO2 nanocomposite antimicrobial coatings for surfaces, dental and orthopaedic implants are emphasized in this review. Mostly, inorganic metals (e.g. copper (Cu), silver (Ag), manganese (Mn), etc), non-metals (e.g. fluorine (F), calcium (Ca), phosphorus (P)) and two-dimensional materials (e.g. MXenes, MOF, graphdiyne) were incorporated with TiO2 to regulate the charge transfer mechanism, surface porosity, crystallinity, and the microbial disinfection efficiency. The antimicrobial activity of TiO2 coatings was evaluated against the most crucial pathogenic microbes such as Escherichia coli, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Legionella pneumophila, Staphylococcus aureus, Streptococcus mutans, T2 bacteriophage, H1N1, HCoV-NL63, vesicular stomatitis virus, bovine coronavirus. Silane functionalizing agents and polymers were used to coat the titanium (Ti) metal implants to introduce superhydrophobic features to avoid the microbial adhesion. TiO2 nanocomposite coatings in dental and orthopaedic metal implants disclosed an exceptional bio-corrosion resistance, durability, biocompatibility, bone-formation capability, and long-term antimicrobial efficiency. Moreover, the commercial trend, techno-economics, challenges, and prospects of antimicrobial nanocomposite coatings are also discussed briefly.

Biomedical polymers are an integral component in a wide range of medical devices because of their many desirable properties. However, extensive use of polymer materials in medical devices has been associated with an increasing incidence of patient infections. Efforts to address this issue have included incorporating antimicrobial additives to develop novel antimicrobial polymeric materials. Silver, with its high toxicity towards bacteria, oligodynamic effect and good thermal stability, has been employed as an additive for polymeric medical devices. In the present study, commercially available elemental (Biogate) and ionic (Ultrafresh 16) silver additives were incorporated into a Polyamide 11 (PA 11) matrix using a compression press. These polymer composites were evaluated for their antimicrobial and ion-release properties. Elemental silver composites were shown to retain their antimicrobial properties for extended periods and actively released silver ions for 84 days; whereas ionic silver composites lost their ion-release activity and, therefore, their antibacterial activity after 56 days. Bacterial log reduction units of 3.87 for ionic silver and 2.41 for elemental silver were identified within 24 h, when tested in accordance with the ISO 22196 test standard; this indicates that ionic silver is more efficient for short-term applications than elemental silver.

Dielectric nanocomposite elastomers based on poly(styrene-ethylene/butylene-styrene) (SEBS) and SEBS-grafted-maleic anhydride (SEBS-g-MA) with barium titanate (BT) suitable for electroactive applications were successfully manufactured by using two corotating twin extrusion systems. The main purpose of the work was to investigate the thermal, mechanical, dielectric, and morphological effects of additives on SEBS and SEBS-g-MA to widen their applications for electroactive applications using fast and more cost-effective simple production process. The morphological characterization showed a good and bad dispersion of BT into SEBS-g-MA and SEBS with 34.9% and −3% dielectric permittivity change in SEBS-g-MA and SEBS upon addition of 10 wt% BT. In addition, dielectric permittivity change, thermal change (enthalpy relaxation and thermal transitions), and mechanical (Young’s modulus, hysteresis loss under multiple stress cycles, storage modulus, loss modulus, and tan δ) properties of elastomers were found to be a function of additive concentration, compatibility and interaction between elastomers and additive type, orientation of additives, and reinforcing factors of additives in elastomers. A simple and effective modeling technique was used to demonstrate the effects of dielectric properties on nanocomposites due to poor dispersion of additives.

This study investigates the effect of supercritical fluid carbon dioxide (scCO2) assisted extrusion on the thermal, mechanical, electrical, and morphological properties of microphase separated Poly(styrene-ethylene/butylene-styrene) [SEBS] triblock at various critical pressures. Thermal degradation analysis reveals 50 °C enhancement in thermal stability of SEBS when extruded with scCO2 compared to SEBS extruded without scCO2. Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) show improved phase separation due to the breakdown of domain size between the hard and soft block and damping losses represented by tan delta. It was found that SEBS processed with scCO2 has low elastic modulus because of foaming as well as restructuring of hard phase around the soft component. Fourier Transform Infrared Spectroscopy (FTIR) shows the interaction of scCO2 in aromatic phenyl rings of S-rich domain in SEBS. Dielectric spectroscopy analysis also confirms scCO2 results in the difference in relaxation of soft and hard blocks within triblock.

Direct incorporation of antimicrobial additive into the polymer matrix is a cost effective approach for the development of polymer/metal antimicrobial composites. Application of these antimicrobial composite systems for manufacturing medical devices addresses the issue of device related infections. In the present study, commercially available inorganic copper based additive, Plasticopper, was incorporated into a Polyamide 11(PA 11) matrix during the polymer processing stage. These polymer composites were evaluated for their morphological, mechanical, antimicrobial and ion release properties. Isothermal crystallisation studies showed that the copper additive acted as a nucleating agent and promoted faster crystallisation. Short term mechanical studies confirmed that the incorporation of copper has reinforcing effect on the composites with 5 and 10% copper loadings and did not adversely affect the short-term mechanical performance of the polymer composites. These composite systems were shown to be active against Escherichia coli ATCC 8739 with > 99.99% reduction in bacterial population. Corresponding ion release profiles for these composites indicated long term antimicrobial activity.

Physician certification boards are an intrinsic part of medical professionalism, and the public is their key stakeholder. A decade ago, the 24 boards of the American Board of Medical Specialties committed to moving beyond the summative evaluation of physicians to a process of continuously evaluating and improving the care they deliver. The American Board of Family Medicine (ABFM) has been a leader in this change and is making strategic investments in the next major evolution of continuous certification. Physicians are frustrated with the pace of change, inability to reliably assess and change their practices, and the perceived risk to both income and professional autonomy. Certifying boards are natural targets for that frustration. Certifying boards have an opportunity to support physicians in improving the quality and safety of healthcare and appeal to physicians' intrinsic motivation for doing so. The ABFM is not retreating from that challenge but is instead listening carefully to family physici...

The primary objective of this research was the biomechanical analysis of a salt-modified polyvinyl alcohol hydrogel, in order to assess its potential for use as an artificial meniscal implant. Aqueous polyvinyl alcohol (PVA) was treated with a sodium sulphate (Na2SO4) solution to precipitate out the polyvinyl alcohol resulting in a pliable hydrogel. The freeze-thaw process, a strictly physical method of crosslinking, was employed to crosslink the hydrogel. Development of a meniscal shaped mould and sample housing unit allowed the production of meniscal shaped hydrogels for direct comparison to human meniscal tissue. Results obtained show that compressive responses were slightly higher in PVA/Na2SO4 menisci, displaying maximum compressive loads of 2472N, 2482N and 2476N for samples having undergone 1, 3 and 5 freeze-thaw cycles respectively. When compared to the human meniscal tissue tested under the same conditions, an average maximum load of 2467.5N was observed. This suggests that the PVA/Na2SO4 menisci are mechanically comparable to the human meniscus. Biocompatibility analysis of PVA/Na2SO4 hydrogels revealed no acute cytotoxicity. The work described herein has innovative potential in load bearing applications, specifically as an alternative to meniscectomy as replacement of critically damaged meniscal tissue in the knee joint where repair is not viable.

Gingival augmentation surgical procedures are commonly used to restore gingival tissues at sites where gingival recession is problematic for the patient or where gingival augmentation/manipulation is required to achieve optimal dental therapeutic results. The goals of this chapter are first to review the types of gingival augmentation procedures commonly used today and next, to summarize the principles and techniques for performing traditional gingival augmentation surgical procedures. Also summarized in this chapter are modifications of gingival augmentation procedures to achieve secondary benefits such as increased vestibule depth, removal of a high frenum attachments, or augmentation of keratinized gingival tissue adjacent to implants. These examples provide a rationale to enhance therapeutic outcomes by adapting the surgical principles of gingival augmentation surgery to specific dental problems.

Silver and silver nanoparticles (AgNPs) exhibit antimicrobial properties against some bacteria, fungi and viruses, however, the ever-increasing application of nanosilver in consumer products, water disinfection and healthcare settings, have raised concerns over the public health/environmental safety of this nanomaterial. The current ubiquity of nanosilver may result in repeated exposure through various routes (skin, inhalation, or ingestion) which may lead to health complications. While there are a number of review articles and case studies published to date on the subject, an updated coherent review that clearly delineates thresholds and safe doses is lacking. Thus, it is plausible to have an overview of the most recent findings on the threshold limits, safe doses of silver and its related nanoscale forms, and the needed actions to ensure the safety and health of human, terrestrial and aquatic lives. This review provides an account of the effects of nanosilver in our daily lives. STATEMENT OF SIGNIFICANCE: This manuscripts is a review of the toxicity of nanosized silver. With respect to the existing literature, it goes beyond stating that there is a knowledge gap, drawing the attention of a wider readership to the ever-growing evidence of nanosilver toxicity to human and nature, and outlining the dose thresholds based on comprehensive data mining and visualisation. There are nearly 500 consumer products that claim to contain nanosilver. Thus, we trust a review of recent conclusive findings is timely. This manuscript is in line with the scope of the Journal, enabling a better understanding of the biological response to a widely-used bionanomaterial. Moreover, it provides a bigger picture of the link between surface properties and biocompatibility of nanosilver in different forms.

Tapered Fiber Optic Sensors (TFOS) are typically interrogated using an Optical Spectrum Analyzer (OSA) or a spectrometer. As a result, multiple TFOS with similar operating wavelengths cannot be interrogated simultaneously. This paper is an extension to the previously published work on “Interrogation of Fiber Bragg Grating Arrays by Illumination using a Low Coherence Interferogram” [1]. In this paper, the ability of the system to simultaneously interrogate multiple TFOS in a single interferometric scan is demonstrated. Varying concentrations of glucose solutions were used to determine the system's sensing capability. Of the two TFOS used, the one with the larger FSR was found to yield a linear resolution of $\mathbf{\sim 2.96\mathbf{e}-3\Delta \mathrm{Rad}/1000\mathbf{ppm}}$ and the other sensor with a smaller FSR yielded a linear resolution of $\mathbf{\sim 5.23\mathbf{e}-3\Delta \mathbf{Rad}/1000\mathbf{ppm}}$ .

To examine the effect of prolonged standing on gluteus medius coactivation and to observe whether the changes in gluteus medius coactivation over time were related to the development of low back pain in elite female field hockey players.Prospective cohort design.Participants were 39 elite female field hockey players (14 with a history of low back pain). Before the prolonged stand, maximal hip abduction strength, side bridge hold endurance and hip abduction range of motion were measured bilaterally. Surface electromyography was collected from the gluteus medius for coactivation analysis during a prolonged stand for 70 min. Low back pain was rated every 10 min on a visual analogue scale.Fourteen of 39 participants developed low back pain. The Time effect was significant for gluteus medius coactivation response (p = 0.003) and visual analogue scale score (p 0.001). There were no significant group × time interactions. Yet athletes who developed pain had higher coactivation for the majority of the stand task.While female field hockey players have high agonist-antagonist coactivation patterns during prolonged standing, stand task is a useful tool to predict low back pain occurrence in players with and without history of pain.

The application of microcrystalline waxes to the bases of art objects is an inexpensive method to provide protection from earthquakes and other ground-borne vibrations. In this paper, four microcrystalline waxes that were developed and/or marketed for art object protection are analysed using Fourier transformed infrared spectroscopy, X-ray diffraction, confocal laser scanning microscopy, differential scanning calorimetry, and dynamic rheological analysis. Results from each analysis are compared for each wax and from previously published sources. Findings are considered with respect to previously published mechanical testing performance, in regards to their potential appropriateness for art object protection. In particular, the glass transition temperatures of two of the waxes, as determined by dynamic rheological analysis, are approximately 35°C. This indicates that these two waxes may be unsuitable for museum usage, if ambient temperatures reach these levels.

Radiosterilisation can induce modifications and/or degradation to transpire in poly(ether-block-amide) (PEBA) following irradiation. The current investigation utilises combined synergistic mixtures of stabilisers to minimise these effects, by melt blending them with the PEBA material. Hindered amine stabilisers (HAS), primary antioxidants and secondary antioxidants were the stabilisers incorporate to reduce/eliminate the effects of 50 kGy electron beam irradiation dose on the material. Results were discussed by comparing the stabilising efficiency of mixtures on the PEBA material in contrast to the control sample. Dynamic frequency sweeps demonstrated the formation of crosslinks, where the degree of crosslinking was dependent on the combination of stabilisers mixed in the base material (PEBA). The storage modulus displayed that PEBA blended with Irganox 565 had very slight changes in contrast to all other samples following irradiation. However, since this sample is a phenol containing system, severe discolouration was observed in comparison to other samples due to the oxidation of the hindered phenol. Overall, this study provides compelling evidence that a combined synergistic mixture of Irganox 565 (multifunctional phenolic antioxidant) and Tinuvin 783 (hindered amide light stabiliser) with PEBA, resulted in the best radiation stability.

Nano-structured dielectric thermoplastic elastomers (DTEs) such as poly(styrene-co-ethylene-co-butylene-styrene) [SEBS] and poly(styrene-co-ethylene-co-butylene-styrene) –grafted- maleic anhydride[SEBS-g-MA] triblock co-polymers have been shown to have superior mechanical performances relative to conventional dielectric elastomers such as silicones because of their morphology; which comprises of continuous hard and soft block copolymers and physical cross-linking between same. However, historically their use in capacitive energy harvesting and sensing applications has been constrained by their relatively low dielectric permittivity. In this work, novel method for increasing the dielectric permittivity of DTE’s while maintaining their mechanical performance by using electrically active modifiers was evaluated. Preliminary results showed a 110% and 99% increase in the dielectric permittivity, and a 787% and 300% increase in the storage modulus, of SEBS and SEBS-g-MA respectively upon addition of 10% carbon black. The storage modulus will be decreased if the materials are pre-strained. These results also indicate that relative changes in the electrical properties of polymer-additive composites is polymer-additive compatibility dependent (i.e. 1.20% decrease in the dielectric permittivity of SEBS and a 32.72% increase in the dielectric permittivity of SEBS-g-MA was observed upon addition of 10% BaTiO3). yes

Hot melt extrusion (HME) is considered an efficient technique in developing solid molecular dispersions, and has been demonstrated to provide sustained, modified and targeted drug delivery resulting in improved bioavailability. However, most commercial enteric or pH-responsive polymers are relatively difficult to process or have high Glass Transition Temperature (Tg) values, making their use with temperature-sensitive drugs, probiotics or biologics not viable. Shellac is a natural thermoplastic, and after a review of current literature on the pharmaceutical HME process, a possible gap in the knowledge of the use of shellac to produce dosage forms by means of HME was identified. This work explores the possibility of SSB® 55 pharmaceutical-grade shellac as a melt-extrudable encapsulation polymer to entrap freeze-dried probiotic powder and to determine bacterial cell viability post-processing. Well-defined strands were produced from the physical mixture of shellac and Biocare® Bifidobacterium Probiotic. FTIR clarified that there are no significant interactions between the probiotic and polymer. All of the samples demonstrated less than 5% degradation over 24 h at pH of both 1.2 and 6.8. At pH 7.4, both loaded samples gave a similar dissolution trend with complete degradation achieved after 10–11 h. Following five-month storage, 57.8% reduction in viability was observed. yes

Radical science and innovation in farming is vital to produce the food that the world will need by 2050. To feed an estimated world population of nine billion people in 2050, 70 % to 100 % increase in food production will be required if it continues rising at the current rate. The aim of this project is to develop novel revolutionary super absorbent hydrogel coatings for agricultural use. Hydrogel seed coatings improve the rate of seed germination and emergence and enhance seed survival during critical development periods, especially under less than optimal conditions. Preliminary work withι-carrageenan hydrogel showed a promising results including higher seed germination rates, faster plant emergence, lower water requirement, enhanced root development and potential carrier of nutrients. Two hydrogel blends – agar/ι-carrageenan and xanthan/κ-carrageenan/ι-carrageenan – were synthesised and characterised in this project as potential seed coating materials based on their biodegradable, non-toxic sugar based natural polymers and their excellent water absorbing/holding capability. The newly formulated hydrogels were characterised by swelling studies, rheological measurements and infrared spectroscopy. It was found that the addition of xanthan/κ-carrageenan intoι-carrageenan hydrogel improved the water absorbing capacity from 117.90 % to 139.05 %, the life-span of the hydrogel from 6 hr to 24 hr in excess water and the gel strength from 108.4 Pa to 267.98 Pa. The addition of agar intoι-carrageenan showed an increase in gel strength and a greater improvement in water holding capacity giving 67.33 % water content whileι-carrageenan on its own had only 39.64 % after 72 hr of incubation at 30 °C, which showed higher potential to be used in drought conditions. The ATR-FTIR results proved that the hydrogels were physically cross-linked. A further evaluation such as the germination profile test is required to test the effectiveness of the hydrogel coatings on seeds. It is anticipated that this work will be extended to coating different seed varieties in the future with these newly developed hydrogels.

The radiation stability of Poly (ether-block-amide) (PEBA) blended with a multifunctional phenolic antioxidant and a hindered amide light stabiliser was examined under various temperatures, packaging and electron beam processing conditions. FTIR revealed that there were slight alterations to the PEBA before irradiation; however, these became more pronounced following irradiation. The effect of varying the temperature, packaging and processing conditions on the resultant PEBA properties was apparent. For example, rheology demonstrated that the structural properties could be enhanced by manipulating the aforementioned criteria. Mechanical testing exhibited less radiation resistance when the PEBA samples were vacuum packed and exposed to irradiation. MFI and AFM confirmed that the melting strength and surface topography could be reduced/increased depending on the conditions employed. From this study it was concluded that virgin PEBA submerged in dry ice with non-vacuum packaging during the irradiation process, provided excellent radiation resistance (20.9% improvement) in contrast to the traditional method.

Miscanthus × giganteus (M × G) was torrefied to improve its thermal and physical properties prior to thermal conversion. Torrefaction was undertaken at a series of temperatures from 230 to 290 °C for residence times varying from 10 to 30 min and the product biomass was characterized in terms of it is suitability as a feedstock for gasification. The properties of the torrefied M × G were improved following treatment. In particular the terrified biomass showed reduced moisture and hemicellulose content a lower ratio of O/C, a more porous structure with larger specific surface area as well as higher content of alkali metals. All these features have positive effect on gasification reactivity suggesting that the torrefaction process is promising pretreatment method for biomass to combine with gasification or co-firing.

High energy electron beam irradiation of Poly (ether-block-amide) (Pebax) can induce modifications and/or degradation to transpire in the material subsequent to treatment. To minimise this, Pebax was blended with three stabilisers where each formulation was subjected to electron beam radiation at doses of 25, 50 and 75 kGy. Mechanical testing revealed that the virgin Pebax and the Pebax blended with Irganox B215 provided the best radiation resistance in terms of the tensile strength, elongation at break and Young's modulus. Upon increase in radiation dose from 25 to 75 kGy, a gradual diminution was observed for the melt flow index (MFI) of the virgin Pebax, whereas Pebax blended with Irganox B215 had a minute effect on the properties post irradiation. This study provides evidence that the stabilisers used can either promote undesirable effects or enhance the radiation resistance of Pebax material following radiation exposure.

With increased demands on catheter balloon functionality, there is an emphasis to blend new materials which can improve mechanical performance. Polymer nanocomposites were prepared by melt blending polyamide 11 (PA 11) with organically modified montmorillonite nanoclay. The effects of incorporating the nanoclay on the short-term mechanical properties of PA 11 were assessed using a design of experiments (DoEs) approach. X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis techniques (DMA) were used to characterise the morphology of the nanocomposites. Design of experiments studies revealed that the optimum nanocomposites properties can be achieved by carefully controlling the melt compounding parameters. XRD and TEM data proved that exfoliated clay morphologies existed within the matrix at low clay loading (2%). Whereas the interaction between the polymer matrix and nanoclay was quantified in the DMA spectra, showed a significant increase in storage modulus (up to 80%). The reinforcing effect of nanoclay within the PA 11 was further investigated using mechanical testing, where significant increases in the ultimate tensile strength and strain at break of reinforced tri-layer balloon tubing were observed.

It is well known that polyurethane (PU) provides good irradiation resistance; however, extremely high irradiation doses can alter the structure and/or function of macromolecules, resulting in oxidation, chain scission and crosslinking. In this present study, modifications to the material characteristics resulting from irradiation were extensively examined through a broad array of analytical techniques. Fourier transform infrared spectroscopy (FTIR) revealed that there were a number of changes to the chemical structure after electron beam irradiation while dynamic frequency sweeps identified an occurrence of crosslinking particularly in the higher irradiation doses. The degree of crosslinking was further analysed by implementing the crosslink density experiment, which illustrated a high level of crosslinking at 200 kGy only. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) identified an increase in phase segregation and as a consequence it could lead to soft segment mobility. This increase in mobility could be responsible for an increase in the degree of chain orientation. Surface morphology of the electron beam irradiated material was determined using scanning electron microscope (SEM) imagery and this provided evidence that the surface of the material had clearly transformed with the development of additional ridges. The influence of such modifications initiated a significant reduction in the contact angle at the upper irradiation dose regime. Overall, this study demonstrated that the medical grade PU was highly affected by radiation exposure, particularly at high irradiation doses.

The response of low density polyethylene (LDPE) to high energy electron beam irradiation in air (10 MeV) between 25 and 400 kGy was examined and compared to non-irradiated polyethylene in terms of the mechanical and structural properties. To quantify the degree of crosslinking, swelling studies were performed and from this it was observed that the crosslink density increased as the irradiation dose increased. Furthermore, a reduction was observed in the numerical data for molar mass between adjacent crosslinks and the number of monomeric units between adjacent crosslinks as the irradiation dose was conducted incrementally. Accelerated aging provided evidence that radicals became trapped in the polymer matrix of LDPE and this in turn initiated further reactions to transpire as time elapsed, leading to additional alteration in the structural properties. Fourier transform infrared spectroscopy (FTIR) was implemented to provide insight into this. This technique established that the aging process had increased the oxidative degradation products due to oxygen permeation into the polymer and double bonds within the material. Mechanical testing revealed an increase in the tensile strength and a decrease in the elongation at break. Accelerated aging caused additional modifications to occur in the mechanical properties which are further elucidated throughout this study. Dynamic frequency sweeps investigated the effects of irradiation on the structural properties of LDPE. The effect of varying the irradiation dose concentration was apparent as this controlled the level of crosslinking within the material. Maxwell and Kelvin or Voigt models were employed in this analytical technique to define the reaction procedure of the frequency sweep test with regards to non-crosslinked and crosslinked LDPE.

The accuracy of treatment monitoring and planning is instrumental to the acceptance of HIFU surgery. The ability to locate, analyze and track a feature of interest during treatment will be affected by patient motion. Additionally, statistical analysis and temperature monitoring algorithms would benefit from the registration of successive frames. In this work two registration algorithms, which have had extensive trials in other imaging applications, are investigated. Their ability to reduce patient respiratory and cardiac motion is within ultrasound sequences, taken during HIFU treatments, is compared. The first algorithm is based on an intensity block matching approach with a similarity measure that incorporates speckle statistics explicitly. The second method registers phase representations of the image with a more general similarity measure. These methods would be expected to succeed on different aspects of the image: phase measurements give weight to features and are rotation and contrast invariant, whereas methods to track speckle are successful in images that lack strong features. In general phase based methods of registration are more robust and have the potential to be extended to multimodality registration (such as MRI to Ultrasound), however in this case tracking speckle may produce better results due to the low signal to noise ratio in ultrasound images taken during HIFU treatments. Numerous examples from HIFU surgery are presented to highlight the performance of each method under a various motion constraints. It is shown that the phase based algorithm is generally superior, except in the close proximity to the skin. © 2007 American Institute of Physics.

High-intensity focused ultrasound (HIFU) has been investigated as a tool for the treatment of cancer for many decades, but is only now beginning to emerge as a potential alternative to conventional therapies. In recent years, clinical trials have evaluated the clinical efficacy of a number of devices worldwide. In Oxford, UK, we have been using the JC HIFU system (HAIFU Technology Company, Chongqing, PR China) in clinical trials since November 2002. This is the first report of its clinical use outside mainland China. The device is non-invasive, and employs an extracorporeal transducer operating at 0.8-1.6 MHz (aperture 12-15 cm, focal length 9-15 cm), operating clinically at Isp (free field) of 5-15 KWcm(-2). The aims of the trials are to evaluate the safety and performance of the device. Performance is being evaluated through two parallel protocols. One employs radiological assessment of response with the use of follow-up magnetic resonance imaging and microbubble-contrast ultrasound. In the other, histological assessment will be made following elective surgical resection of the HIFU treated tumours. Eleven patients with liver tumours have been treated with HIFU to date. Adverse events include transient pain and minor skin burns. Observed response from the various assessment modalities is discussed.

High-intensity focused ultrasound (HIFU) provides a potentially non-invasive alternative to conventional therapies. We have been using the extracorporeal ultrasound-guided Model-JC Tumor Therapy System (HAIFU™ Technology Co, China) in clinical trials to evaluate the safety and feasibility of treating renal and liver tumours. 30 patients have been treated (22 liver and 8 kidney tumours), all of whom were available for adverse event reporting. Of the 22 liver tumours, 20 are evaluable for response to treatment; 14 were followed up with magnetic resonance imaging (MRI) alone, and 6 with both MRI and histological resection. Evidence of ablation was seen in 20/20 (100%) cases radiologically, and 6/6 (100%) cases histologically. Of the 8 kidney tumours treated, 7 are evaluable; 2 were followed up with MRI alone, and 5 with both MRI and histological resection. Evidence of ablation was seen in 4/7 (57%) radiologically and 1/5 (20%) histologically. Mild, moderate or severe transient pain was reported by 16 (53%), 7 (23%) and 1 (3%) patients, respectively. Superficial skin toxicity was seen in 7 patients (23%). Renal function was unaffected, and all patients were fit for discharge from hospital the day after treatment. Early results show that this technique is feasible, and carries a low morbidity. © 2005 American Institute of Physics.

Radiation is currently being exploited to modify polyethylene in order to improve properties for various applications such as hip replacements. This paper thoroughly examines the effects of high energy electron beam irradiation (10 MeV) on low density polyethylene (LDPE) material. ASTM (American Society for Testing and Materials) testing specimens were manufactured from LDPE and subjected to a broad range of doses ranging between 25 and 400 kGy at room temperature in an air atmosphere. Extensive characterisation techniques such as modulated differential scanning calorimetry (MDSC) and the Fourier transform infrared spectroscopy (FTIR) were conducted on the non-irradiated and irradiated samples. While considering the semicrystalline nature of LDPE during the MDSC experiment, the melting temperature ( T m ) and the temperature crystallinity ( T c ) were calculated. This revealed that the T m and the T c decreased in temperature as the irradiation dose increased. The FTIR analysis was implemented to evaluate the presence of polar species such as carbonyl groups and trans-vinylene double bond groups. The IR spectra illustrated that the concentration of characteristic bands for trans-vinylene bonds increased with increasing radiation dose indicating the formation of carbonyl bond groups. Furthermore, the results demonstrated an occurrence of oxidative degradation due to the formation of carbonyl groups at 1718 cm −1 .

Hydrogels formulated from single polymers are often insufficient in terms of their mechanical properties for use as bone substitute materials. Hence, hydrogels synthesised from combinations of polymers have been investigated to optimise the performance of such materials. In the current study, polypropylene glycol dimethacrylate was added to polyethylene glycol dimethacrylate of a variety of molecular weights and photopolymerised to form a series of hydrogels. Polyethylene glycol and polypropylene glycol have the same chemical structure with the exception of a methyl group on the later. Herein, the influence of the methyl group of polypropylene glycol on the mechanical properties of hydrogels for bone regeneration applications is reported. For both unconfined and cyclic compression testing, results demonstrated that the incorporation of PEGDMA into the precursor improves the compression strength of the hydrogels. For example, in unconfined compression tests the Young’s modulus varied between 6.62 ± 0.31 MPa and 8.08 ± 0.81 MPa with the incorporation of PEGDMA 400.

It is desirable to produce cryopreservable cell-laden tissue-engineering scaffolds whose final properties can be adjusted during the thawing process immediately prior to use. Polyvinyl alcohol (PVA)-based solutions provide platforms in which cryoprotected cell suspensions can be turned into a ready-to-use, cell-laden scaffold by a process of cryogelation. In this study, such a PVA system, with DMSO as the cryoprotectant, was successfully developed. Vascular smooth muscle cell (vSMC)-encapsulated cryogels were investigated under conditions of cyclic strain and in co-culture with vascular endothelial cells to mimic the environment these cells experience in vivo in a vascular tissue-engineering setting. In view of the cytotoxicity DMSO imposes with respect to the production procedure, carboxylated poly-L-lysine (COOH-PLL) was substituted as a non-cytotoxic cryoprotectant to allow longer, slower thawing periods to generate more stable cryogels. Encapsulated vSMC with DMSO as a cryoprotectant responded to 10% cyclic strain with increased alignment and proliferation. Cells were stored frozen for 1 month without loss of viability compared to immediate thawing. SMC-encapsulated cryogels also successfully supported functional endothelial cell co-culture. Substitution of COOH-PLL in place of DMSO resulted in a significant increase in cell viability in encapsulated cryogels for a range of thawing periods. We conclude that incorporation of COOH-PLL during cryogelation preserved cell functionality while retaining fundamental cryogel physical properties, thereby making it a promising platform for tissue-engineering scaffolds, particularly for vascular tissue engineering, or cell preservation within microgels.

The current contribution investigates the potential use of styrene butadiene styrene (SBS) block copolymer grafted with N-vinyl-2-pyrrolidinone (NVP) for use as a novel biomaterial. SBS-g-NVP was synthesised using UV polymerisation and analytical techniques such as differential scanning calorimetry (DSC), attenuated total reflectance infrared Fourier transform spectrometry (ATR-FTIR), dynamic thermal mechanical analysis (DMTA) and goniometry were used to characterise the grafted copolymers. The ATR-FTIR spectrum for grafted SBS-g-NVP copolymer exhibits a shoulder at 1714 cm −1 , which is associated with carbonyl stretching of NVP. DSC analysis showed the grafted copolymers had broader thermographs within the butadiene rich domain resulting in increased T g values, suggesting that grafting occurred. Confirmation of this was established by the use of DMTA, where the T g (−90 °C) which represents the butadiene domain increased to −76 °C, thus proving grafting. The surface chemistries of the grafted copolymers have also been altered which is reflected in the goniometry results which show a dramatic reduction in contact angles (113° to 7°), which is a desired property for biomedical polymers.

The term ‘nanoclay’ generically refers to the natural clay mineral, montmorillonite, with silica and alumina as the dominant constituents. The incorporation of nanoclays into polymeric systems dramatically enhances their barrier properties as well as their thermal and mechanical resistance. Consequently, nanoclays are employed in a wide range of industrial applications with recent studies reporting potential use in the modulation of drug release. With the increase in manufacturing of nanoclay-containing products, information on the toxicological and health effects of nanoclay exposure is warranted. Thus, the objective of the present study was to evaluate the cytotoxicity of two different nanoclays: the unmodified nanoclay, Cloisite Na+®, and the organically modified nanoclay, Cloisite 93A®, in human hepatoma HepG2 cells. Following 24 h exposure the nanoclays significantly decreased cell viability. Cloisite Na+ induced intracellular reactive oxygen species (ROS) formation which coincided with increased cell membrane damage, whilst ROS generation did not play a role in Cloisite 93A-induced cell death. Neither of the nanoclays induced caspase-3/7 activation. Moreover, in the cell culture medium the nanoclays aggregated differently and this appeared to have an effect on their mechanisms of toxicity. Taken together, our data demonstrate that nanoclays are highly cytotoxic and as a result pose a possible risk to human health. Copyright © 2010 John Wiley & Sons, Ltd.

The body of work described in this research article outlines the use of titanium microparticles as fillers in the production of a polyether-block-amide (Pebax 5533) based composite for medical applications. Virgin polyether-block-amide was compared with titanium filled composites with loadings of 40 and 60% by weight prepared using twin screw extrusion and compression moulding. The materials were characterised using a range of mechanical, thermal, toxicological and surface analysis techniques. Fourier transform infrared spectroscopy indicated that no chemical interaction occurred between the filler particles and the host polymer matrix. Thermal analysis of the composites indicated that as the blend composition varied, so too did the melting behaviour. The inclusion of the titanium microparticles was observed to increase the flow viscosity, tensile strength, hardness and Young’s modulus of the composites whilst also resulting in a rougher surface with lower surface energy.

Hydrogels fabricated from single polymers have been extensively investigated for wound healing applications. However, in many cases a single polymer cannot meet divergent demands in terms of both properties and performance. In this work, a two phase hydrogel was prepared by physically imbedding a xerogel in the core of a freeze thawed hydrogel. The outer hydrogel was prepared by freeze thawing poly (vinyl alcohol) (PVA) and poly (acrylic acid) (PAA) while the xerogels were prepared by UV polymerisation of 1-vinyl-2-pyrrolidinone (NVP). The rheological results indicated that the two phase hydrogels over a period of 2 weeks formed a strong interface and demonstrated greater physical strength. This suggested that the inner gel containing PVP diffused into the PVA/PAA hydrogel, which in turn increased hydrogen bonding, resulting in the overall increase in the stiffness of the gel. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) confirmed hydrogen bonding had occurred between the constituents of the two phase hydrogels. Thermal analysis suggested that T g of each of the samples was above 80 °C, which indicated no impact on the behaviour of the gel at body temperature, but did however, give an indication of the stiffness of the dry polymer.

The work undertaken investigates the mechanical and thermal properties of a styrene butadiene styrene (SBS) grafted with N-isopropylacrylamide (NIPAAm) for potential use in the field of biomaterials. SBS-g-NIPAAm was synthesised using UV polymerisation and analytical techniques such as differential scanning calorimetry (DSC), attenuated total reflectance Fourier transform spectrometry (ATR-FTIR), dynamic mechanical thermal analysis (DMTA) and tensile tests were used to characterise the grafted copolymers. The ATR-FTIR spectrum for NIPAAm illustrates bands corresponding to C=O stretching and NH bending for secondary amides at 1655 and 1544 cm−1, respectively. These bands are represented as shoulders in SBS-g-NIPAAm copolymers. In relation to the thermal analysis, the butadiene domain present in the SBS and the grafted SBS copolymers were analysed using DSC. It was evident that all of the grafted samples have a broad thermal transition when compared to the PB domain present in SBS, suggesting that grafting had occurred within each of the SBS-g-NIPAAm copolymers. This was confirmed by the use of DMTA, where the results showed an increase in Tg values from −92 to −74 °C for SBS-g-NIPAAm copolymers.

The current study involves the development of a hydrogel carrier for a H(2)O(2) delivery system. In this work poly (vinyl alcohol) (PVA) and poly (acrylic acid) (PAA) based hydrogels were prepared, and their mechanical and physical properties examined. The novel aspect of this research is the differing functionality created by varying the concentration of H(2)O(2). The mechanical and thermal properties were determined by parallel plate rheometry and modulated differential scanning calorimetry (MDSC) respectively. The results indicated that the hydrogels containing H(2)O(2) are significantly weaker than those synthesised using water alone at test temperatures of 30 and 45 degrees C. MDSC analysis suggested that thermal transitions occur at temperatures that may make these hydrogels useful as temperature sensitive drug delivery systems. The chemical structure of the hydrogels was confirmed by means of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), while swelling experiments in distilled water indicate that the swelling of the gels is temperature dependent.

The work undertaken investigates the mechanical and thermal properties of styrene butadiene styrene (SBS) grafted with acrylic acid (AA) for use as a potential biomedical material. SBS-g-AA was synthesised by UV polymerisation and analytical techniques such as differential scanning calorimetry (DSC), attenuated total reflectance infrared Fourier transform spectrometry (ATR-FTIR), dynamic mechanical thermal analysis (DMTA) and tensile tests were used to characterise the grafted copolymers. From the DSC analysis, the glass transitions of polystyrene (PS) and polybutadiene (PB) domains present in the SBS copolymer were detected at 67 °C and − 90 °C respectively. ATR-FTIR spectral analysis was used in conjunction with the DSC thermographs to analyse the grafted copolymers. The peak (1711 cm − 1 ) associated with C O stretching in poly acrylic acid was located at 1725 cm − 1 on the grafted SBS-g-AA copolymer which confirmed grafting took place. Mechanical testing was carried out to analyse the physical attributes of the grafted copolymers. It was found that a decrease in Young's modulus and stress at break occurred for SBS-g-AA copolymers which were soxhlet extracted using chloroform (washed). It was evident from the DMTA results that the glass transition values for each of the washed grafted samples increased, thus establishing that grafting had occurred onto the various butadiene segments along the SBS backbone. The results showed that the hydrophilic monomer was successfully grafted onto a hydrophobic polymer and the mechanical and thermal properties were in the useful range for biomedical applications.

The work undertaken investigates the spectral, thermal and surface characteristics of a random styrene butadiene rubber (SBR) with monomeric graft(s) of acrylic acid (AA), N-vinyl-2-pyrrolidinone (NVP) or N-isopropylacrylamide (NIPAAm) synthesised using UV polymerisation. The grafted materials were characterised by differential scanning calorimetry (DSC), modulated differential scanning calorimetry (MDSC), attenuated total reflectance infrared Fourier transform spectrometry (ATR-FTIR) and atomic force microscopy (AFM). Thermograph analysis has shown an endothermic transition occurring at ~75 °C for all random SB-g-NVP copolymers, whereas the T g value for random SB copolymer was found at 60 °C, thus suggesting that a chemical reaction between styrene and NVP had occurred. Similar thermal profiles to that of random SB-g-NVP copolymers were evident when random SB was UV polymerised with AA. When NIPAAm was grafted onto random SB, a notable exothermic transition was evident in all samples tested using DSC. It was established using MDSC that this exothermic transition was caused by the breakdown of crosslinks as a result of UV polymerisation.

Hydrogel based devices belong to the group of swelling controlled drug delivery systems. Temperature responsive poly(N-isopropylacrylamide)-poly(vinylpyrrolidinone) random copolymers were produced by free radical polymerisation, using 1-hydroxycyclohexylphenyketone as an ultraviolet-light sensitive initiator, and poly(ethylene glycol) dimethacrylate as the crosslinking agent (where appropriate). The hydrogels were synthesised to have lower critical solution temperatures (LCST) near body temperature, which is favourable particularly for 'smart' drug delivery applications. Two model drugs (diclofenac sodium and procaine HCl) were entrapped within these xerogels, by incorporating the active agents prior to photopolymerisation. The properties of the placebo samples were contrasted with the drug-loaded copolymers at low levels of drug integration. Modulated differential scanning calorimetry (MDSC), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and atomic force microscopy (AFM) were used to investigate the influence of the drugs incorporated on the solid-state properties of the xerogels. MDSC and swelling studies were carried out to ascertain their effects on the LCST and swelling behaviour of the hydrated samples. In all cases, drug dissolution analysis showed that the active agent was released at a slower rate at temperatures above the phase transition temperature. Finally, preliminary in vitro cytotoxicity evaluations were performed to establish the toxicological pattern of the gels.