Effect of carbon black nanoparticle intrinsic properties on the self-monitoring performance of glass fibre reinforced composite rods

Self-monitoring composite rods, made of an internal conductive core surrounded by an external structural skin, were manufactured and tested. Both parts were made of glass fibre-epoxy. Electrical conductivity was achieved in the inner core by incorporating as an alternative high surface area or low surface area carbon black in the resin. Self-monitoring performance was assessed by simultaneous mechanical and electrical resistance measurements. The aim was to correlate the electrical resistance variation to stress. Only one type of material showed appropriate self-monitoring properties, since increase of electrical resistance was recorded at increasing loading (both monothonic and cyclic tensile loading), while electrical resistance recovery at high loads was found in the other case. Calorimetric analysis, rheological measurements and SEM observations were carried out to explain this result. Filler dispersion seems to be the key feature affecting the self-monitoring properties. Only high surface area nanoparticles can ensure self-monitoring reliability.     

Post-transplant proteinuria associated with everolimus: Definition of main features with proteomics

Little is known on both the composition and mechanism(s) of proteinuria associated with the use of mTOR inhibitors, in particular of Everolimus (E). We characterized urinary proteins utilizing an integrated proteomics approach (quantitative essays, 2‐DE, MALDI‐TOF, Western blot) in 48 renal transplant recipients who were alternatively treated with E (n = 31) or with enteric coated mycophenolic acid (EC‐MPA) (n = 17). Twelve E patients (39%) developed high (>3 g/day) or intermediate proteinuria (1–3 g) compared to four (23%) of the EC‐MPA group. Urinary proteins (p<0.001), β2 microglobulin (p<0.001) and α1microglobulin (p<0.025) were higher in E than in EC‐MPA, appeared more rapidly and were inversely correlated with the day of treatment. Proteomics showed a marked increase of all urinary components in E and EC‐MPA patients, major changes involving typical components of glomerular damage (albumin, α1‐Zn glycoprotein, α2HS glycoprotein, leucin‐richα2‐glycoprotein) and specific bio‐markers for E (clusters of α1‐antitrypsin fragments and monoclonal λ chains). Finally, inter‐α‐trypsin‐inhibitor heavy chain H4 precursor was decreased in E and EC‐MPA urine compared to normal urine. In conclusion, E induced massive and generalized proteinuria of mixed glomerular and tubular origin that was correlated with the start of treatment and reached a nephrotic range in few cases. Specific urinary markers reflect renal alterations related to the transplant or specific alterations associated with the drug.     

Proteins and protein fragments in nephrotic syndrome: Clusters, specificity and mechanisms

Proteinuria is the hallmark of renal diseases and the characterization of the urinary protein composition may become an important source of information for diagnosis and research. So far, protein analysis in urine has been utilized for a generic individuation of site-specific defects (glomerular vs. tubular) but there is a need for an extension of proteomics to specific urinary biomarkers in selected clinical conditions. The identification of fragments of proteins in plasma and urine may increase the spectrum of urinary biomarkers. The unique speculative application so far proposed for protein fragments is nephrotic syndrome, and specifically focal segmental glomerulosclerosis, in which case they reflect intrinsic proteolysis occurring in plasma and represent surrogate biomarkers of the disease activity. Albumin is probably the most studied protein. Several of the albumin fragments present a peculiar distribution of the fingerprint peptide pattern containing both the N-terminal region and the C-terminal domain with a complete lack of any MS signals for the internal sequence region. Their characterization utilizing new strategies based on 2-D nondenaturing electrophoresis is now in progress. Studies on a direct characterization of proteases in plasma and urine will also define the participation of proteases to the genesis of renal diseases.     

Alan Turing and the Mathematical Objection

This paper concerns Alan Turing's ideas about machines, mathematical methods of proof, and intelligence. By the late 1930s, Kurt Gödel and other logicians, including Turing himself, had shown that no finite set of rules could be used to generate all true mathematical statements. Yet according to Turing, there was no upper bound to the number of mathematical truths provable by intelligent human beings, for they could invent new rules and methods of proof. So, the output of a human mathematician, for Turing, was not a computable sequence (i.e., one that could be generated by a Turing machine). Since computers only contained a finite number of instructions (or programs), one might argue, they could not reproduce human intelligence. Turing called this the ``mathematical objection' to his view that machines can think. Logico-mathematical reasons, stemming from his own work, helped to convince Turing that it should be possible to reproduce human intelligence, and eventually compete with it, by developing the appropriate kind of digital computer. He felt it should be possible to program a computer so that it could learn or discover new rules, overcoming the limitations imposed by the incompleteness and undecidability results in the same way that human mathematicians presumably do.     

Electrospun poly(ε-caprolactone)/Ca-deficient hydroxyapatite nanohybrids: Microstructure,mechanical properties and cell response by murine embryonic stem cells

Nanohybrid scaffolds mimicking extracellular matrix are promising experimental models to study stem cell behaviour, in terms of adhesion and proliferation. In the present study, the structural characterization of a novel electrospun nanohybrid and the analysis of cell response by a highly sensitive cell type, embryonic stem (ES) cells, are investigated. Ca-deficient hydroxyapatite nanocrystals (d-HAp) were synthesized by precipitation. Fibrous PCL/d-HAp nanohybrids were obtained by electrospinning, d-HAp content ranging between 2 and 55 wt.%. Electrospun mats showed a non-woven architecture, average fiber size was 1.5 ±0.5 μm, porosity 80–90%, and specific surface area 16 m² g^? 1. Up to 6.4 wt.% d-HAp content, the nanohybrids displayed comparable microstructural, mechanical and dynamo-mechanical properties. Murine ES cell response to neat PCL and to nanohybrid PCL/d-HAp (6.4 wt.%) mats was evaluated by analyzing morphological, metabolic and functional markers. Cells growing on either scaffold proliferated and maintained pluripotency markers at essentially the same rate as cells growing on standard tissue culture plates with no detectable signs of cytotoxicity, despite a lower cell adhesion at the beginning of culture. These results indicate that electrospun PCL scaffolds may provide adequate supports for murine ES cell proliferation in a pluripotent state, and that the presence of d-HAp within the mat does not interfere with their growth.     

Chronic renal replacement therapy in children: which index is best for adequacy?

BACKGROUND: The dialysis dose, Kt/V, and Solute Removal Index (SRI) have been proposed as tools to measure and compare adequacy of different renal replacement therapies in adults. The aim of our study was to elucidate whether the Kt/V and SRI could be appropriate parameters to compare different treatments and define adequacy targets in children. METHODS: Twenty-two pediatric chronic dialysis patients (2 to 17 years) were prospectively studied. Six patients were on continuous ambulatory peritoneal dialysis (CAPD), 7 patients were on automatic nightly peritoneal dialysis (ANPD), and 9 were on hemodialysis (HD). Patients had no peritonitis and were not hospitalized during the previous two months and, as proved by growth and subjective well being, were in steady state condition at the initiation of the protocol. As a consequence, the treatment delivered was assumed to be adequate and the prospective analysis was carried out within one month. Urea levels in dialysate, plasma and urine were measured to determine urea kinetics and measure adequacy parameters. RESULTS: Instantaneous urea clearance was much higher when hemodialysis was used (124.67 +/- 32.04 ml/min) compared to CAPD (2.79 +/- 0.29 ml/min) and ANPD (6.60 +/- 1.42 ml/min), as expected. The Urea dialytic clearance per week was greater in HD (67320 +/- 17299 ml) than in CAPD(28144 +/- 2895 ml) and ANPD (29910 +/- 4234 ml). Residual renal function contributed to the overall weekly clearance by 47% in CAPD, while it was only by 19% in HD and 26% in ANPD. The overall weekly clearance was therefore 79,842 ml/week in HD, 53,340 ml/week in CAPD and 41,012 ml/week in ANPD. Weekly dialytic Kt/V results were much higher in HD (3.75) than in CAPD (1.78) and ANPD (2.37). To these values, the renal Kt/V was added, reaching the values of overall (dialytic + renal) weekly Kt/V of 4.53 in HD, 3.41 in CAPD and 3.41 in ANPD. Although higher Kt/V values were observed in HD, when the SRI % was considered, HD appeared to be less efficient compared with the other two techniques. Since postdialytic rebound in HD patients averaged 22.5%, we may speculate that hemodialysis in children is less efficient than continuous or daily peritoneal dialysis because of a remarkable cardipulmonary recirculation and solute sequestration. CONCLUSION: In the global evaluation, dialysis SRI% appears to be more reliable as an index of adequacy compared to Kt/V in children. At least an integration between the two indices is strongly recommended.     

Synthesis and characterization of poly(ε-caprolactone) reinforced with aligned hybrid electrospun PMMA/nano-Al2O3 fibre mats by film stacking

PMMA and PMMA/10 wt% nano-Al₂O₃ fibre mats were produced by means of electrospinning and used as reinforcing phase of poly(ε-caprolactone) matrix. The composite films were fabricated by means of film-stacking technique. SEM observations showed good wettability of PMMA-based fibres by the PCL matrix, confirming that a strong interface was formed. The Al₂O₃ nanoparticles were well-distributed along the polymeric fibres. The introduction of PMMA fibres as a reinforcement led to a clear benefit in terms of the mechanical strength (11.5 ± 0.5 MPa), the value for neat PCL being 8.2 ± 2.2 MPa. The tensile strength was further increased when the fibres were loaded with nano-Al₂O₃ (14.4 ± 0.6 MPa) due to both the presence of the ceramic filler and the smaller diameter of the composite fibres. A less marked improvement was instead found on stiffness.     

Jean-Pierre Dupuy,The Mechanization of Mind: On the Origins of Cognitive Science

Minds and Machines -     

Eu-doped titania nanofibers: processing, thermal behaviour and luminescent properties

Undoped and Europium-doped titania nanofibers have been fabricated by electrospinning technique, using a single multielement Titanium/Europium source. In this communication we present the synthesis, structural and spectroscopic characterisation of Eu-doped TiO2 nanofibers starting from polyvinylpyrrolidone, titanium tetraisopropoxide (Ti(OiPr)4) and Eu(hfa)3 x diglyme (Hhfa = 1,1,1,5,5,5-hexafluoroacetyacetone, diglyme = CH3O(CH2CH2O)2CH3). The chosen system allowed to investigate a wide compositional range, i.e., from 3 to 10% mol of Eu3+. Microstructure was studied by means of scanning electron microscopy (SEM), thermal behaviour followed by thermogravimetric and differential thermal analysis (TG-DTA). Phase analysis was performed by means of X-ray diffraction (XRD) and high temperature X-ray diffraction analysis (HT-XRD) up to 1100 degrees C. Luminescence properties were investigated by means of luminescence spectroscopy, using a laser excitation source at 395 nm. All electrospun materials consisted of randomly oriented nanofibers of fairly uniform diameter. The average fiber size was 80-100 nm and 40 nm for, respectively, Eu-doped and undoped TiO2 calcinated at 500 degrees C. The presence of Europium shifted toward higher values either the crystallization temperature of anatase and the anatase to rutile phase transition, the latter being accompanied by the formation of the Eu2Ti2O7 phase. The doped samples showed a strong luminescence of Eu3+ ions. The emission spectra were dominated by the 5D0 --> 7F2 emission, suggesting a notable distortion around the Eu3+ ions. The broadening of the bands pointed to the presence of a relevant inhomogeneous disorder around the Eu3+ sites. The Eu3+ doped TiO2 nanofibers showed a higher emission intensity with respect to the PVP/TiO2 ones.     

Design of Ceramic Materials for Chemical Sensors: SmFeO3 Thick Films Sensitive to NO2

Ultrafine SmFeO₃ powders were prepared by the thermal decomposition at 700°C of the corresponding hexacyanocomplex, Sm[Fe(CN)₆]·4H₂O. These powders were used for the preparation of pastes which were deposited as thick films on alumina substrates with comb-type Au electrodes. The films were fired at different temperatures in the 800-1000°C range. The content of α-terpineol, a component of the organic vehicle, was varied in the range 0.0046-4 wt%. The microstructure, the chemical composition at the surface, the electrical conductivity, and the NO₂ sensing properties of the films were investigated. The content of α-terpineol strongly influenced the electrical conductivity and its activation energy. A significant reduction in the NO₂ response was observed for the films containing smaller amounts of α-terpineol, together with an increase in conductivity. On the other hand, the largest NO₂ response was observed for the films fired at 1000°C when 4 wt% of α-terpineol was used. Such increase in conductivity is attributed to a different oxygen surface layer on the SmFeO₃ surface, which is induced by the decomposition reaction of α-terpineol during sintering. The materials processing parameters are thus of primary concern for the NO₂ sensing properties of the SmFeO₃ thick films. The correlations found between activation energy, NO₂ sensitivity, and materials characteristics (influenced by the preparation parameters) are reported. These correlations can be used to design the gas-sensing properties of SmFeO₃ thick films for the optimization of their sensing characteristics.