Imaging of nuclear magnetic resonance spin–lattice relaxation activation energy in cartilage

Samples of human and bovine cartilage have been examined using magnetic resonance imaging to determine the proton nuclear magnetic resonance spin–lattice relaxation time, T1, as a function of depth within through the cartilage tissue. T1 was measured at five to seven temperatures between 8 and 38°C. From this, it is shown that the T1 relaxation time is well described by Arrhenius-type behaviour and the activation energy of the relaxation process is quantified. The activation energy within the cartilage is approximately 11 ± 2 kJ mol−1 with this notably being less than that for both pure water (16.6 ± 0.4 kJ mol−1) and the phosphate-buffered solution in which the cartilage was immersed (14.7 ± 1.0 kJ mol−1). It is shown that this activation energy increases as a function of depth in the cartilage. It is known that cartilage composition varies with depth, and hence, these results have been interpreted in terms of the structure within the cartilage tissue and the association of the water with the macromolecular constituents of the cartilage

Dissolution of hemp yarns by 1-ethyl-3-methylimidazolium acetate studied with time-temperature superposition

This study investigated the dissolution of hemp yarns in the ionic liquid 1-ethyl-3-methylimidazolium acetate. The yarns were submerged in the ionic liquid at various temperatures and times, then coagulated in water. This resulted in the formation of a composite yarn where two optical microscopy methods were employed to track the growth of the coagulated matrix. In the first, the submerged yarns within water were measured from a side view. In the second, the yarns were dried then analysed by encapsulating in epoxy resin. In both methods, the growth of the swollen ring thickness and the coagulated fraction was tracked as a function of time and temperature. It was found to obey time-temperature superposition, giving a dissolution activation energy of . In water the yarn is swollen; the swelling ratios of the different regions were calculated to be for the outer dissolved ring and the undissolved core, respectively. A novel finding in this study was that the growth of the coagulated region follows a diffusion process, increasing with the square root of time, and so could be modelled to give a diffusion coefficient for the ionic liquid of . This compared well with previously published NMR data for a saturated cellulose solution (23.5%). This strongly suggests that the diffusion of the ions through a saturated layer of cellulose solution controls the dissolution of the yarn. This finding has significant implications for cellulose-based composite production and thus the recycling of cellulose textiles

Time–Temperature Superposition of the Dissolution of Wool Yarns in the Ionic Liquid 1-Ethyl-3-methylimidazolium Acetate

The dissolution of wool yarns in the ionic liquid 1-ethyl-3-methyl-imidazolium acetate [C2mim][OAc] has been investigated. Wool yarns were submerged into [C2mim][OAc] and dissolved for various times and temperatures before coagulating with water. Optical microscopy was used to track the yarn’s cross-sectional area. We propose that there are two competing dissolution processes, one rate-limited by disulfide bonds at low temperatures (LTs), and a second by hydrogen bonds at high temperatures (HTs), with a crossover point between the two regimes at 70 ℃. The corresponding activation energies were ELT = 127 ± 9 kJ/mol and EHT = 34 ± 1 kJ/mol. The remaining area of the dissolved wool yarn could be shifted via time–temperature superposition to plot a single master curve of area against time for both regions. Finally, the dissolution could be modelled by a diffusion process, giving self-diffusion coefficients for the [C2mim][OAc] ions (0.64–15.31 × 10−13 m2/s)

Effect of water on the dissolution of flax fiber bundles in the ionic liquid 1-ethyl-3-methylimidazolium acetate

This work investigated the dissolution rate of flax fibers in the ionic liquid 1-ethyl-3-methylimidazolium acetate [C2mim] [OAc] with the addition of a cellulose anti-solvent, water. The dissolution process was studied as a function of time, temperature and water concentration. Optical microscopy is used to analyse the resultant partially dissolved fibers. Distilled water was added to the solvent bath at the concentrations of 1%, 2% and 4% by weight in order to understand its influence on the dissolution process. The effect of the addition of even small amounts of water was found to significantly decrease the speed of dissolution, decreasing exponentially as a function of water concentration. The resulting data of both pure (as received from the manufacturers) ionic liquid and ionic liquid/anti-solvent mixtures showed the growth of the coagulated fraction as a function of both dissolution time and temperature followed time temperature superposition. An Arrhenius behavior was found, enabling the measurement of the activation energy for the dissolution of flax fiber. The activation energy of the IL as received (0.2% water) was found to be 64 ± 5 kJ/mol. For 1%, 2% and 4% water systems, the activation energies were found to be 74 ± 7 kJ/mol, 97 ± 3 kJ/mol and 116 ± 0.6 kJ/mol respectively. Extrapolating these results to zero water concentration gave a value for the hypothetical dry IL (0% water) of 58 ± 4 kJ/mol. The hypothetical dry ionic liquid is predicted to dissolve cellulose 23% faster than the IL as received (0.2% water)

Design of experiments in the optimization of all-cellulose composites

In this work, statistical design of experiments (DoE) was applied to the optimization of all cellulose composites (ACCs) using cotton textile and interleaf films under applied heat and pressure. The effects of dissolution temperature, pressure and time on ACC mechanical properties were explored through a full factorial design (23) and later optimized using Response Surface Methodology. It was found that the experimental design was effective at revealing the underlying relationship between Young’s modulus and processing conditions, identifying optimum temperature and time settings of 101 °C and 96.8 min respectively, to yield a predicted Young’s modulus of 3.3 GPa. This was subsequently validated through the preparation of in-lab test samples which were found to exhibit a very similar Young’s modulus of 3.4 ± 0.2 GPa, confirming the adequacy of the predictive model. Additionally, the optimized samples had an average tensile strength and peel strength of 72 ± 2 MPa and 811 ± 160 N/m respectively, as well as a favorable density resulting from excellent consolidation within the material microstructure. This work highlights the potential of DoE for future ACC process understanding and optimization, helping to bring ACCs to the marketplace as feasible material alternatives

Mechanical and Thermal Evaluation of Carrageenan/Hydroxypropyl Methyl Cellulose Biocomposite Incorporated with Modified Starch Corroborated by Molecular Interaction Recognition

Vegetarian hard capsule has attracted surging demand as an alternative to gelatin; however, only few have been commercialized. Carrageenan extracted from seaweed has the potential to be utilized as a hard capsule material. Improving the mechanical and thermal properties of carrageenan biocomposite is therefore of great importance for future use in the drug delivery system. Hence, carboxymethyl sago starch (CMSS) was incorporated to strengthen the carrageenan biocomposite in a concentration range from 0 to 1.0% w/v. The intermolecular hydrogen bonding formed between carrageenan and CMSS was revealed via density functional theory (DFT) calculations and substantiated by 1H NMR and FTIR spectra. The result showed that the hydrogen bond is established between hydroxyl (carrageenan)–carbonyl (CMSS) groups at a distance of 1.87 Å. The bond formation subsequently increased the tensile strength of the biocomposite film and the loop strength of the hard capsule by 20.6 and 7.7%, respectively. The glass transition temperature of the film was increased from 37.8 to 47.8 °C, increasing the thermal stability. The activation energy upon decomposition of the film is 74.4 kJ·mol–1, representing a 26.2% increase over the control carrageenan. These findings demonstrate that incorporation of CMSS increases the properties of carrageenan biocomposite and provides a promising alternative to animal-based hard capsules

Social Entrepreneurship and Broader Theories: Shedding New Light on the “Bigger Picture”

This article documents the results of a research workshop bringing together six perspectives on social entrepreneurship. The idea was to challenge existing concepts of the economy, the firm, and entrepreneurship in order to shed new light on social entrepreneurship and on our existing theoretical frameworks. The first two contributions use a macro-perspective and discuss the notion of adaptive societies and the tragedies of disharmonization, respectively. Taking a management perspective, the next two focus on the limits of conventional assumptions in management theory, particularly human capital theory and resource-based view. The final two contributions follow an entrepreneurship perspective highlighting the usefulness of mobilization theory and the business model lens to social entrepreneurship. Despite this diversity, all contributions share the fact that they challenge narrow definitions of the unit of analysis in social entrepreneurship; they illustrate the aspect of social embeddedness, and they argue for an open-but-disciplined diversity of theories in social entrepreneurship research

ERS statement on standardisation of cardiopulmonary exercise testing in chronic lung diseases

The objective of this document was to standardise published cardiopulmonary exercise testing (CPET) protocols for improved interpretation in clinical settings and multicentre research projects. This document: 1) summarises the protocols and procedures used in published studies focusing on incremental CPET in chronic lung conditions; 2) presents standard incremental protocols for CPET on a stationary cycle ergometer and a treadmill; and 3) provides patients’ perspectives on CPET obtained through an online survey supported by the European Lung Foundation. We systematically reviewed published studies obtained from EMBASE, Medline, Scopus, Web of Science and the Cochrane Library from inception to January 2017. Of 7914 identified studies, 595 studies with 26 523 subjects were included. The literature supports a test protocol with a resting phase lasting at least 3 min, a 3-min unloaded phase, and an 8- to 12-min incremental phase with work rate increased linearly at least every minute, followed by a recovery phase of at least 2–3 min. Patients responding to the survey (n=295) perceived CPET as highly beneficial for their diagnostic assessment and informed the Task Force consensus. Future research should focus on the individualised estimation of optimal work rate increments across different lung diseases, and the collection of robust normative data.The document facilitates standardisation of conducting, reporting and interpreting cardiopulmonary exercise tests in chronic lung diseases for comparison of reference data, multi-centre studies and assessment of interventional efficacy. http://bit.ly/31SXeB

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

14 p.Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change