Poly(Ethylene Furanoate) along Its Life-Cycle from a Polycondensation Approach to High-Performance Yarn and Its Recyclate.

We report on the pilot scale synthesis and melt spinning of poly(ethylene furanoate) (PEF), a promising bio-based fiber polymer that can heave mechanical properties in the range of commercial poly(ethylene terephthalate) (PET) fibers. Catalyst optimization and solid state polycondensation (SSP) allowed for intrinsic viscosities of PEF of up to 0.85 dL·g-1. Melt-spun multifilament yarns reached a tensile strength of up to 65 cN·tex-1 with an elongation of 6% and a modulus of 1370 cN·tex-1. The crystallization behavior of PEF was investigated by differential scanning calorimetry (DSC) and XRD after each process step, i.e., after polymerization, SSP, melt spinning, drawing, and recycling. After SSP, the previously amorphous polymer showed a crystallinity of 47%, which was in accordance with literature. The corresponding XRD diffractograms showed signals attributable to α-PEF. Additional, clearly assignable signals at 2θ > 30° are discussed. A completely amorphous structure was observed by XRD for as-spun yarns, while a crystalline phase was detected on drawn yarns; however, it was less pronounced than for the granules and independent of the winding speed.

Melt-Spinning of an Intrinsically Flame-Retardant Polyacrylonitrile Copolymer.

Poly(acrylonitrile) (PAN) fibers have two essential drawbacks: they are usually processed by solution-spinning, which is inferior to melt spinning in terms of productivity and costs, and they are flammable in air. Here, we report on the synthesis and melt-spinning of an intrinsically flame-retardant PAN-copolymer with phosphorus-containing dimethylphosphonomethyl acrylate (DPA) as primary comonomer. Furthermore, the copolymerization parameters of the aqueous suspension polymerization of acrylonitrile (AN) and DPA were determined applying both the Fineman and Ross and Kelen and Tüdõs methods. For flame retardancy and melt-spinning tests, multiple PAN copolymers with different amounts of DPA and, in some cases, methyl acrylate (MA) have been synthesized. One of the synthesized PAN-copolymers has been melt-spun with propylene carbonate (PC) as plasticizer; the resulting PAN-fibers had a tenacity of 195 ± 40 MPa and a Young's modulus of 5.2 ± 0.7 GPa. The flame-retardant properties have been determined by Limiting Oxygen Index (LOI) flame tests. The LOI value of the melt-spinnable PAN was 25.1; it therefore meets the flame retardancy criteria for many applications. In short, the reported method shows that the disadvantage of high comonomer content necessary for flame retardation can be turned into an advantage by enabling melt spinning.

Depression moderates the associations between beliefs about medicines and medication adherence in patients with rheumatoid arthritis: Cross-sectional study.

The 'necessity-concerns framework' postulates that patients' adherence behaviour is influenced by beliefs about the necessity and the concerns patients have regarding their prescribed medicines. We hypothesized that depression moderates the associations between beliefs about medicines and medication adherence among people with rheumatoid arthritis. Using multivariate logistic regression, we observed that people experiencing more depressive symptoms showed stronger associations between necessity beliefs and adherence as well as attenuated associations between concerns and adherence, respectively, in a cross-sectional sample ( N = 361). Thus, depression moderates the associations postulated in the 'necessity-concerns framework' in a differential way in people with rheumatoid arthritis.

Pain, social support and depressive symptoms in patients with rheumatoid arthritis: testing the stress-buffering hypothesis.

This study investigated as to how social support influences health among people with rheumatoid arthritis (RA). We refer to the stress-buffering hypothesis of social support which suggests that the negative consequences of stressors on health outcomes can be buffered by social support. In this study, pain represents a stressor and depressive symptoms represent negative health outcomes. It was hypothesized that higher levels of social support should attenuate the association between pain and depression in RA. A cross-sectional study was conducted in 361 patients with RA. They completed questionnaires on social support, depression and perceived pain. Linear regression analysis was applied, with pain as the main explanatory variable, depression as a dependent variable, and an interaction term "social support × pain". Both pain and social support showed significant associations with depression, with more severe pain and lower social support going along with a higher depression score. However, the interaction term "social support × pain" was not significant, indicating that social support did not attenuate the association between pain and depression. Social support was inversely associated with the experience of depressive symptoms among people suffering from RA. However, it had no buffering effect in attenuating the postulated association between the stressor "pain" and the negative health outcomes assessed as depressive symptoms. The stress-buffering hypothesis of social support was not supported by data from this study among people suffering from RA.

Poly(phosphorodiamidate)s by Olefin Metathesis Polymerization with Precise Degradation.

Degradable polymers are a currently growing field of research for biomedical and materials science applications. The majority of such compounds are based on polyesters and polyamides. In contrast, their phosphorus-containing counterparts are much less studied, in spite of their potential precise degradation profile and biocompatibility. Herein, the first library of poly(phosphorodiamidate)s (PPDAs) with two P-N bonds forming the polymer backbone and a pendant P-OR group is prepared through acyclic diene metathesis polymerization. They are designed to vary in their hydrophilicity and are compared with the structural analogues poly(phosphoester)s (PPEs) with respect to their thermal properties and degradation profiles. The degradation of PPDAs can be controlled precisely by the pH: under acidic conditions the P-N linkages in the polymer backbone are cleaved, whereas under basic conditions the pendant ester is cleaved selectively and almost no backbone degradation occurs. The PPDAs exhibit distinctively higher thermal stability (from thermogravimetric analysis (TGA)) and higher glass transition and/or melting temperatures (from differential scanning calorimetry (DSC)) compared with analogous PPEs. This renders this exotic class of phosphorus-containing polymers as highly promising for the development of future drug carriers or tissue engineering scaffolds.

The pro-active payload strategy significantly increases selective release from mesoporous nanocapsules.

The controlled release of payloads from mesoporous silica nanocapsules (SiNCs) consisting of stimulus-responsive shells is of considerable interest in applications such as self-healing materials and drug delivery. However, the release of payloads from SiNCs before application of external triggers (i.e. non-selective release) remains a formidable challenge. In fact, the non-selective release of payloads from SiNCs occurs because of the mesoporous nature of the silica shell that cannot trap payloads in the core of SiNCs perfectly. We establish an efficient and straightforward strategy based on the encapsulation of a pro-active payload to hinder the non-selective release of small payloads from mesoporous capsules. A pro-active payload is defined as a compound that is converted to an active functional molecule in the environment where it is needed. In this sense, it is a generalization of a prodrug. Encapsulating a pro-active payload instead of a payload allowed hindering the non-selective release of the payload from SiNCs. A selective release of the payload could be achieved upon reduction of the encapsulated pro-active payload. Furthermore, the total amount of released substance is significantly enhanced by introducing responsive groups in the silica shell. These results show that the pro-active payload strategy combined with the use of stimulus-responsive materials can be successfully exploited to achieve selective release of cargo from mesoporous nanocapsules.

Isomer-directed structural diversity and its effect on the nanosheet exfoliation and magnetic properties of 2,3-dimethylsuccinate hybrid frameworks.

The structures of seven new transition metal frameworks featuring Mn, Co, or Zn and either the meso or chiral D and L isomers of the 2,3-dimethylsuccinate ligand are reported. Frameworks that exhibit two-dimensional covalently bonded layers with weak interlayer interactions can be made with all three cations by incorporation of the chiral isomers of the 2,3-dimethylsuccinate ligand. The formation of such structures, suitable for the creation of nanosheets via exfoliation, is, however, not as ubiquitous as is the case with the 2,2-dimethylsuccinate frameworks since frameworks that incorporate the meso-2,3-dimethylsuccinate ligand form three-dimensional structures. This clear distinction between the formation of structures with covalent connectivity in two and three dimensions, depending on the choice of 2,3-dimethylsuccinate isomer, is due to the different conformations adopted by the backbone of the ligand. The chiral isomer prefers to adopt an arrangement with its methyl and carboxylate groups gauche to the neighboring functional groups of the same type, while the meso-ligand prefers to adopt trans geometry. A gauche-arrangement of the methyl groups places them on the same side of the ligand, making this geometry ideal for the formation of layered structures; a trans-relationship leads to the methyl groups being further apart, reducing their steric hindrance and making it easier to accommodate them within a three-dimensional structure. The ease of exfoliation of the layered frameworks is examined and compared to those of known transition metal 2,2-dimethylsuccinate frameworks by means of UV-vis spectroscopy. It is suggested that layered frameworks with more corrugated surfaces exfoliate more rapidly. The size, structure, and morphology of the exfoliated nanosheets are also characterized. The magnetic properties of the paramagnetic frameworks reveal that only the three dimensionally covalently bonded phases containing meso-2,3-DMS in trans-arrangements order magnetically. These frameworks are antiferromagnets at low temperatures, although the Co compound undergoes an unusual antiferromagnetic to ferromagnetic transition with increasing applied magnetic field.

A novel anthropometric chart for craniofacial surgery.

Various indices and measurements of the growing cranial vault exist, but there is no single head-shape chart specific to craniofacial surgery. The authors have produced a reliable head-shape chart that will enable accurate charting of patients with craniosynostosis both in the preoperative and postoperative period.One thousand eighty-two participants were used to obtain normal anthropometric measurements, specifically the ear-to-ear measurement and the glabella-to-external occipital protuberance measurement. Both male and female participants aged 6 months to 25 years were used to obtain these measurements. These measurements were correlated with the cephalic index as described by Farkas according to the different age groups.A head-shape chart has been created for males and females using the normal ear-to-ear measurements and the cephalic index that define both qualitative and quantitative elements of the growing skull. Craniofacial surgeons may find this chart useful for managing patients with craniosynostosis. This chart is also useful in the assessment of how the skull grows after surgery.