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SynopsisPolycarbonate blends with poly(e-caprolactone) were prepared by both melt-blending and solution-blending techniques, and the properties of these blends were studied by thermal analytical and dynamic mechanical testing methods. Each blend composition was found to have a single glass transition temperature, and the temperature location of this transition was found to be a function only of blend composition and to be independent of the blending technique employed. This behavior led to the conclusions that these two polymers form blends containing a single amorphous phase comprised of the two materials and that this miscible phase results primarily from physical rather than chemical interactions between the two polymers. A reversible liquid-liquid-type phase separation was found to occur when the blend system was heated to high melt temperatures. The temperature required for phase separation, the lower critical solution temperature, was found to vary with blend composition and component molecular weight in the manner expected from thermodynamic considerations. The level of crystallinity of poly(c-caprolactone) was affected by the presence of the polycarbonate. The polycarbonate also crystallized to an appreciable extent in many of the blends.

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BackgroundChronic refractory angina is a challenging clinical problem with limited treatment options. The results of early cardiovascular stem cell trials using ABMMC have been promising but have utilized intracoronary or intramyocardial delivery. The goal of the study was to evaluate the safety and early efficacy of autologous bone marrow derived mononuclear cells (ABMMC) delivered via percutaneous retrograde coronary sinus perfusion (PRCSP) to treat chronic refractory angina (CRA).MethodsFrom May 2005 to October 2006, 14 patients, age 68 +/- 20 years old, with CRA and ischemic stress-induced myocardial segments assessed by SPECT received a median 8.19*108 ± 4.3*108 mononuclear and 1.65*107 ± 1.42*107 CD34+ cells by PRCSP..ResultsABMMC delivery was successful in all patients with no arrhythmias, elevated cardiac enzymes or complications related to the delivery. All but one patient improved by at least one Canadian Cardiovascular Society class at 2 year follow-up compared to baseline (p < 0.001). The median baseline area of ischemic myocardium by SPECT of 38.2% was reduced to 26.5% at one year and 23.5% at two years (p = 0.001). The median rest left ventricular ejection fraction by SPECT at baseline was 31.2% and improved to 35.5% at 2 year follow up (p = 0.019).ConclusionsPRCSP should be considered as an alternative method of delivery for cell therapy with the ability to safely deliver large number of cells regardless of coronary anatomy, valvular disease or myocardial dysfunction. The clinical improvement in angina, myocardial perfusion and function in this phase 1 study is encouraging and needs to be confirmed in randomized placebo controlled trials.

BackgroundHemoglobin is a rich source of biologically active peptides, some of which are potent antimicrobials (hemocidins). A few hemocidins have been purified from the midgut contents of ticks. Nonetheless, how antimicrobials are generated in the tick midgut and their role in immunity is still poorly understood. Here we report, for the first time, the contribution of two midgut proteinases to the generation of hemocidins.ResultsAn aspartic proteinase, designated BmAP, was isolated from the midgut of Rhipicephalus (Boophilus) microplus using three chromatographic steps. Reverse transcription-quantitative polymerase chain reaction revealed that BmAP is restricted to the midgut. The other enzyme is a previously characterized midgut cathepsin L-like cysteine proteinase designated BmCL1. Substrate specificities of native BmAP and recombinant BmCL1 were mapped using a synthetic combinatorial peptide library and bovine hemoglobin. BmCL1 preferred substrates containing non-polar residues at P2 subsite and polar residues at P1, whereas BmAP hydrolysed substrates containing non-polar amino acids at P1 and P1'.ConclusionsBmAP and BmCL1 generate hemocidins from hemoglobin alpha and beta chains in vitro. We postulate that hemocidins may be important for the control of tick pathogens and midgut flora.

Fourier‐transform infrared (FTIR) spectroscopy was used to examine the interactions in miscible blends of a styrene (92%)/acrylic acid (8%) copolymer (SAA8) with poly(methyl methacrylate) (PMMA). From the residue or interaction spectra and shifts of carbonyl and carboxylic acid stretching bands, it is concluded that there is a significant specific interaction involving hydrogen bonding between the carbonyl groups of the PMMA and the carboxylic groups of the SAA8. Similar FTIR spectra of some low‐molecular‐weight liquid analogs for the various monomer units of these polymers do not indicate a comparable interaction. This explains why direct calorimetry with these compounds fails to model correctly the expected exothermic mixing of the blends. Furthermore, the role of the aromatic moiety in the SAA polymer appears to reduce the degree of self‐association of the carboxylic acid groups based on results for the model compounds. Coupled with molecular rigidity, the above mechanism makes the carboxylic acid units in SAA8 more available for interaction with the PMMA carbonyls.

Commonly isolated carbon nanotubes in suspension have been modelled as a perfectly straight structure. Nevertheless, single-wall carbon nanotubes (SWNTs) contain naturally side-wall defects and, in consequence, natural bent configurations. Hence, a semi-flexile filament model with a natural bent configuration was proposed to represent physically the SWNT structure. This continuous model was discretized as a non-freely jointed multi-bead-rod system with a natural bent configuration. Using a Brownian dynamics algorithm the dynamical mechanical contribution to the linear viscoelastic response of naturally bent SWNTs in dilute suspension was simulated. The dynamics of such system shows the apparition of new relaxation processes at intermediate frequencies characterized mainly by the activation of a mild elasticity. Storage modulus evolution at those intermediate frequencies strongly depends on the flexibility of the system, given by the rigidity constant of the bending potential and the number of constitutive rods.

Advanced macroscopic fiber orientation models depend on a variety of phenomenological parameters. The aim of this work is to identify a fiber orientation model for concentrated short fiber reinforced polymers, which depends on a minimum number of parameters. A sliding plate experiment with repeatable initial conditions and a couette experiment, to cover high strains, are used to define an experimental validation curve. The major fiber orientation models (Folgar and Tucker, nematic, reduced strain closure [RSC], anisotropic rotary diffusion, ARD‐RSC) are fitted to the validation curve. Since a slow evolution can be observed, the RSC model is necessary to fit the measured fiber orientation evolution. The dependency of the RSC model on the initial fiber orientation state and the influence of closure approximations are evaluated. Two validation cases show that the obtained parameters give good results in shear dominant parts, but are not able to predict fiber orientation in other flow regimes accurately.