Elastic and electrical properties of graphite and talc filler reinforced polypropylene (PP) composites

Graphite filler reinforced polypropylene (PP) composites and talc filler reinforced (PP) composites were prepared by compression molding at 160 ºC. Mechanical and electrical properties were studied. The tensile strength of the composites decreases with the increase of filler addition and also with the increase of wt.% of filler. But, a slight improvement of the Young's modulus of the filaments reinforced with different wt.% of filler is observed. It was found that the Bulk density of test materials increased with the fillers content. Capacitance decreases with the increase of both frequency and voltage which suggest good electrical properties of PP-graphite composites and PP-talc composites. All of these results indicated that PP-graphite composites are better than the PP-talc composites

A novel fluorescein-bisphosphonate based diagnostic tool for the detection of hydroxyapatite in both cell and tissue models

Abstract A rapid and efficient method for the detection of hydroxyapatite (HAP) has been developed which shows superiority to existing well-established methods. This fluorescein-bisphosphonate probe is highly selective for HAP over other calcium minerals and is capable of detecting lower levels of calcification in cellular models than either hydrochloric acid-based calcium leaching assays or the Alizarin S stain. The probe has been shown to be effective in both in vitro vascular calcification models and in vitro bone calcification models. Moreover we have demonstrated binding of this probe to vascular calcification in rat aorta and to areas of microcalcification, in human vascular tissue, beyond the resolution of computed tomography in human atherosclerotic plaques. Fluorescein-BP is therefore a highly sensitive and specific imaging probe for the detection of vascular calcification, with the potential to improve not only ex vivo assessments of HAP deposition but also the detection of vascular microcalcification in humans

Mutation analysis of 18 nephronophthisis associated ciliopathy disease genes using a DNA pooling and next generation sequencing strategy

Background Nephronophthisis associated ciliopathies (NPHP-AC) comprise a group of autosomal recessive cystic kidney diseases that includes nephronophthisis (NPHP), Senior-Loken syndrome (SLS), Joubert syndrome (JBTS), and Meckel-Gruber syndrome (MKS). To date, causative mutations in NPHP-AC have been described for 18 different genes, rendering mutation analysis tedious and expensive. To overcome the broad genetic locus heterogeneity, a strategy of DNA pooling with consecutive massively parallel resequencing (MPR) was devised.Methods In 120 patients with severe NPHP-AC phenotypes, five pools of genomic DNA with 24 patients each were prepared which were used as templates in order to PCR amplify all 376 exons of 18 NPHP-AC genes (NPHP1, INVS, NPHP3, NPHP4, IQCB1, CEP290, GLIS2, RPGRIP1L, NEK8, TMEM67, INPP5E, TMEM216, AHI1, ARL13B, CC2D2A, TTC21B, MKS1, and XPNPEP3). PCR products were then subjected to MPR on an Illumina Genome-Analyser and mutations were subsequently assigned to their respective mutation carrier via CEL I endonuclease based heteroduplex screening and confirmed by Sanger sequencing.Results For proof of principle, DNA from patients with known mutations was used and detection of 22 out of 24 different alleles (92% sensitivity) was demonstrated. MPR led to the molecular diagnosis in 30/120 patients (25%) and 54 pathogenic mutations (27 novel) were identified in seven different NPHP-AC genes. Additionally, in 24 patients only single heterozygous variants of unknown significance were found.Conclusions The combined approach of DNA pooling followed by MPR strongly facilitates mutation analysis in broadly heterogeneous single gene disorders. The lack of mutations in 75% of patients in this cohort indicates further extensive heterogeneity in NPHP-AC

Phase transitions in the system poly(N-isopropylacrylamide)/water and swelling behaviour of the corresponding networks.

The phase behaviour of linear poly(N-isopropylacrylamide) (PNIPA) and chemically cross-linked PNIPA in water has been determined by calorimetric and optical techniques. Experiments for the linear polymer were conducted for three different molar masses and encompassed the whole accessible concentration range. In addition the binodal of the ‘monomer’ N-(isopropyl)propionamide (NIPPA) was determined by cloud point measurements. The phase behaviour was analysed in terms of the Flory–Huggins–Staverman theory amended with a strong concentration dependent interaction function. The analysis established that PNIPA/water is exemplar of Type II phase behaviour, indicating that the system does not fit the classic Flory–Huggins scheme. Distinctive of Type II behaviour is the existence of an off-zero liquid–liquid critical composition for a hypothetical polymer of infinite molar mass and the absence of the classic FH T-critical state. The Type II phase behaviour of the linear polymer is also found in the network and is shown to be responsible for the discontinuous volume response of the PNIPA gel. The peculiar swelling behaviour is a direct consequence of the invariant interference of the swelling curve with the liquid–liquid miscibility gap. Finally, the dependence of the enthalpy of melting of water in the polymer solution is not related to the formation of a strong complex between the polymer and the water molecules. Instead, the crystallisation and melting of water are impeded by the vitrification of the aqueous polymer solution

Phase transitions in the system poly(N-isopropylacrylamide)/water and swelling behaviour of the corresponding networks.

The phase behaviour of linear poly(N-isopropylacrylamide) (PNIPA) and chemically cross-linked PNIPA in water has been determined by calorimetric and optical techniques. Experiments for the linear polymer were conducted for three different molar masses and encompassed the whole accessible concentration range. In addition the binodal of the ‘monomer’ N-(isopropyl)propionamide (NIPPA) was determined by cloud point measurements. The phase behaviour was analysed in terms of the Flory–Huggins–Staverman theory amended with a strong concentration dependent interaction function. The analysis established that PNIPA/water is exemplar of Type II phase behaviour, indicating that the system does not fit the classic Flory–Huggins scheme. Distinctive of Type II behaviour is the existence of an off-zero liquid–liquid critical composition for a hypothetical polymer of infinite molar mass and the absence of the classic FH T-critical state. The Type II phase behaviour of the linear polymer is also found in the network and is shown to be responsible for the discontinuous volume response of the PNIPA gel. The peculiar swelling behaviour is a direct consequence of the invariant interference of the swelling curve with the liquid–liquid miscibility gap. Finally, the dependence of the enthalpy of melting of water in the polymer solution is not related to the formation of a strong complex between the polymer and the water molecules. Instead, the crystallisation and melting of water are impeded by the vitrification of the aqueous polymer solution

Phase transitions in the system poly(N-isopropylacrylamide)/water and swelling behaviour of the corresponding networks.

The phase behaviour of linear poly(N-isopropylacrylamide) (PNIPA) and chemically cross-linked PNIPA in water has been determined by calorimetric and optical techniques. Experiments for the linear polymer were conducted for three different molar masses and encompassed the whole accessible concentration range. In addition the binodal of the ‘monomer’ N-(isopropyl)propionamide (NIPPA) was determined by cloud point measurements. The phase behaviour was analysed in terms of the Flory–Huggins–Staverman theory amended with a strong concentration dependent interaction function. The analysis established that PNIPA/water is exemplar of Type II phase behaviour, indicating that the system does not fit the classic Flory–Huggins scheme. Distinctive of Type II behaviour is the existence of an off-zero liquid–liquid critical composition for a hypothetical polymer of infinite molar mass and the absence of the classic FH T-critical state. The Type II phase behaviour of the linear polymer is also found in the network and is shown to be responsible for the discontinuous volume response of the PNIPA gel. The peculiar swelling behaviour is a direct consequence of the invariant interference of the swelling curve with the liquid–liquid miscibility gap. Finally, the dependence of the enthalpy of melting of water in the polymer solution is not related to the formation of a strong complex between the polymer and the water molecules. Instead, the crystallisation and melting of water are impeded by the vitrification of the aqueous polymer solution

Physical, optical and thermal properties of graphite and talc filler reinforced polypropylene (PP) composites

Graphite filler reinforced polypropylene (PP) composites and talc filler reinforced PP composites were prepared by compression molding at 160⁰ C. Physical, optical and thermal properties were studied. Bulk density of test materials increased with the fillers content. The composites show good optical properties. Absorbance decreases with the increase of wavelength and the highest absorbance peak was found near about 200 nm. Their thermal stability has also been studied. The results reveal that the addition of 5 wt.% of graphite or talc improves the thermal stability. There is an initial DTA peak for both PP-graphite and PP-talc composites. Thermal analysis of PP-graphite filler composites and PP-talc filler composites show that thermal degradation of PP sheet starts ahead of composites. Dynamic mechanical analysis shows high elasticity and low energy loss both for 5% of PP-graphite and PP-talc composites. All of these results indicated that PP-graphite composites are better than the PP-talc composites