Poly(lactic acid), PLA, is a polyester that can be produced from lactic acid derived from renewable resources. This polymer offers attracting uses in packaging industry due to its biodegradability ...and high tensile strength. However, PLA is quite brittle, which limits its applications. To overcome this drawback, PLA was plasticized with epoxy-type plasticizer derived from a fatty acid, octyl epoxy stearate (OES) at different loadings (1, 3, 5, 10, 15, and 20 phr). The addition of OES decreases the glass transition temperature and provides a remarkable increase in elongation at break and impact-absorbed energy. Plasticizer saturation occurs at relatively low concentrations of about 5 phr OES; higher concentration leads to phase separation as observed by field emission scanning electron microscopy (FESEM). Optimum balanced mechanical properties are obtained at relatively low concentrations of OES (5 phr), thus indicating the usefulness of this material as environmentally friendly plasticizer for PLA industrial formulations.
•Thermoplastic starch offers partial miscibility with PLA as evidenced by FESEM.•The addition of 4–6phr MLO leads to an elongation at break of 140–160%.•MLO also provides a compatibilization effect.
...In this work, poly(lactic acid), PLA and thermoplastic starch, TPS blends (with a fixed content of 30wt.% TPS) were prepared by melt extrusion process to increase the low ductile properties of PLA. The TPS used contains an aliphatic/aromatic biodegradable polyester (AAPE) that provides good resistance to aging and moisture. This blend provides slightly improved ductile properties with an increase in elongation at break of 21.5% but phase separation is observed due to the lack of strong interactions between the two polymers. Small amounts of maleinized linseed oil (MLO) can positively contribute to improve the ductile properties of these blends by a combined plasticizing-compatibilizing effect. The elongation at break increases over 160% with the only addition of 6phr MLO. One of the evidence of the plasticizing-compatibilizing effect provided by MLO is the change in the glass transition temperature (Tg) with a decrease of about 10°C. Field emission scanning electron microscopy (FESEM) of PLA-TPS blends with varying amounts of maleinized linseed oil also suggests an increase in compatibility.
Schizophrenia (SZ) is a severe neuropsychiatric disorder associated with disrupted connectivity within the thalamic-cortico-cerebellar network. Resting-state functional connectivity studies have ...reported thalamic hypoconnectivity with the cerebellum and prefrontal cortex as well as thalamic hyperconnectivity with sensory cortical regions in SZ patients compared with healthy comparison participants (HCs). However, fundamental questions remain regarding the clinical significance of these connectivity abnormalities.
Resting state seed-based functional connectivity was used to investigate thalamus to whole brain connectivity using multi-site data including 183 SZ patients and 178 matched HCs. Statistical significance was based on a voxel-level FWE-corrected height threshold of p < 0.001. The relationships between positive and negative symptoms of SZ and regions of the brain demonstrating group differences in thalamic connectivity were examined.
HC and SZ participants both demonstrated widespread positive connectivity between the thalamus and cortical regions. Compared with HCs, SZ patients had reduced thalamic connectivity with bilateral cerebellum and anterior cingulate cortex. In contrast, SZ patients had greater thalamic connectivity with multiple sensory-motor regions, including bilateral pre- and post-central gyrus, middle/inferior occipital gyrus, and middle/superior temporal gyrus. Thalamus to middle temporal gyrus connectivity was positively correlated with hallucinations and delusions, while thalamus to cerebellar connectivity was negatively correlated with delusions and bizarre behavior.
Thalamic hyperconnectivity with sensory regions and hypoconnectivity with cerebellar regions in combination with their relationship to clinical features of SZ suggest that thalamic dysconnectivity may be a core neurobiological feature of SZ that underpins positive symptoms.
Apolipoprotein E (APOE) dependent lifetime risks (LTRs) for Alzheimer Disease (AD) are currently not accurately known and odds ratios alone are insufficient to assess these risks. We calculated AD ...LTR in 7351 cases and 10 132 controls from Caucasian ancestry using Rochester (USA) incidence data. At the age of 85 the LTR of AD without reference to APOE genotype was 11% in males and 14% in females. At the same age, this risk ranged from 51% for APOE44 male carriers to 60% for APOE44 female carriers, and from 23% for APOE34 male carriers to 30% for APOE34 female carriers, consistent with semi-dominant inheritance of a moderately penetrant gene. Using PAQUID (France) incidence data, estimates were globally similar except that at age 85 the LTRs reached 68 and 35% for APOE 44 and APOE 34 female carriers, respectively. These risks are more similar to those of major genes in Mendelian diseases, such as BRCA1 in breast cancer, than those of low-risk common alleles identified by recent GWAS in complex diseases. In addition, stratification of our data by age groups clearly demonstrates that APOE4 is a risk factor not only for late-onset but for early-onset AD as well. Together, these results urge a reappraisal of the impact of APOE in Alzheimer disease.
The nanoscale piezoelectric and ferroelectric behavior of barium titanate/poly(vinylidene fluoride) (BT/PVDF) nanocomposite films has been investigated by means of atomic force microscopy (AFM). An ...uniaxial stretching step was first carried out to promote the polar β crystal phase of the PVDF matrix, as confirmed by infrared spectroscopy and piezoelectric force microscopy (PFM) analysis. Fragmentation of the original polymer crystalline structure upon drawing, as evidenced by the presence of nanometric crystalline blocks did not damage the composite film, thanks to the strong interfacial cohesion between ceramic and polymer brought by nitrodopamine functionalization of the BT inclusions. By scanning the composite surface using PFM, highly piezo-active regions were evidenced and attributed to the BT nanoparticles that could not be identified on the AFM topography images. The precise manipulation of the ferroelectric polarization states in these individual BT grains embedded into the PVDF matrix has been successfully achieved, confirmed by the local electromechanical deformation simultaneously detected. Reversible switching of the out-of-plane polarization orientation spatially confined into the particles was evidenced. The ability of the contact PFM tool to both directly visualize individual piezoelectric nanofillers dispersed into a polymer matrix and monitor the polarization states is demonstrated, thus highlighting the versatility of PFM for the advanced characterization of electroactive nanocomposites.
The present work is focused on the development of binary blends from poly(hydroxybutyrate) (PHB) and poly(caprolactone) (PCL). Miscibility, mechanical and thermal properties as well as blends ...morphology are evaluated in terms of the blend composition. Binary PHB–PCL blends were manufactured by melt compounding in a twin screw co-rotating extruder and injection molded. The composition of PHB–PCL covered the full range between individual polymers at 25 wt% increments. The obtained results show that PCL acts as an impact modifier, thus leading to an increase in flexibility and ductility as the PCL content in the PHB–PCL blends increases with a noticeable increase in elongation at break and on the energy absorption in impact conditions. The tensile strength and the elastic modulus decrease with increasing PCL content in the PHB–PCL blends; nevertheless, the flexural strength and the flexural modulus reach the highest values for the PHB–PCL blends containing 25 wt% PCL, with a remarkable decrease over this composition. The analysis of fractured surfaces by field emission scanning electron microscopy and thermal properties obtained by differential scanning calorimetry (DSC) and TGA give clear evidences of the immiscibility of these two biodegradable polymers. Additionally, DSC results showed an increase in crystallinity of both PHB and PCL with regard to individual polymers for PHB–PCL blends containing 25 wt% PCL. Furthermore, an increase in the degradation onset (
T
0
) of about 30 °C higher was detected for the same blends. Dynamic mechanical thermal analysis showed slightly shifted glass transition temperatures of each individual polymer, thus indicating that although both PHB and PCL are not fully miscible, some interactions between them occur.
The aim of this study was to evaluate the association between diabetes and cognitive performance in a nationally representative study in Brazil. We also aimed to investigate the interaction between ...frailty and diabetes on cognitive performance. A cross-sectional analysis of the Brazilian Longitudinal Study of Aging (ELSI-Brazil) baseline data that included adults aged 50 years and older was conducted. Linear regression models were used to study the association between diabetes and cognitive performance. A total of 8,149 participants were included, and a subgroup analysis was performed in 1,768 with hemoglobin A1c data. Diabetes and hemoglobin A1c levels were not associated with cognitive performance. Interaction of hemoglobin A1c levels with frailty status was found on global cognitive z-score (P-value for interaction=0.038). These results suggested an association between higher hemoglobin A1c levels and lower cognitive performance only in non-frail participants. Additionally, undiagnosed diabetes with higher hemoglobin A1c levels was associated with both poor global cognitive (β=-0.36; 95%CI: -0.62; -0.10, P=0.008) and semantic verbal fluency performance (β=-0.47; 95%CI: -0.73; -0.21, P=0.001). In conclusion, higher hemoglobin A1c levels were associated with lower cognitive performance among non-frail participants. Higher hemoglobin A1c levels without a previous diagnosis of diabetes were also related to poor cognitive performance. Future longitudinal analyses of the ELSI-Brazil study will provide further information on the role of frailty in the association of diabetes and glycemic control with cognitive decline.
This works aims at the development thermosetting resins derived from epoxidized linseed oil (ELO) of high biobased content, by using a mixture of crosslinking agents, i.e. methyl nadic anhydride ...(MNA) and maleinized linseed oil (MLO). By using only MNA as crosslinking agent, the obtained resins are characterized by high stiffness and, consequently, high fragility. When MLO content increasing in the crosslinking mixture, up to 25 wt%, a decrease in mechanical resistant and thermomechanical is detected, thus indicating that MLO can provide flexibility to ELO-based thermosetting resins which is an interesting issue to obtain tailored properties by selecting the appropriate mixture composition. In general, the thermosetting resin crosslinked with 10 wt% MLO and 40 wt% MNA gives balanced properties together with noticeable biobased content, thus broadening the potential of these materials for uses in green composites and coatings.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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