Isotactic and syndiotactic polypropylene/multi-wall carbon nanotube composites: synthesis and properties

Isotactic polypropylene (iPP) and syndiotactic polypropylene (sPP) nanocomposites containing 0.1–3.5 wt.% multi-wall carbon nanotubes (MWCNTs) have been synthesized via in situ polymerization method with the use of C₂- and C_s- symmetry zirconocenes activated by methylaluminoxane (MAO) in liquid propylene medium. Fracture morphology studies by SEM reveal different MWCNT dispersion efficiency in various polymer matrices, which arises from the catalytic peculiarities of the composite synthesis. Considerable Young’s modulus enhancement of iPP and sPP (25–66%) takes place even at low MWCNT loadings (below 0.5 wt.%). The obtained nanocomposites can find use as efficient electromagnetic shielding materials and microwave absorbing filters due to relatively low permittivity values and considerable dielectric losses in microwave range. Calorimetry data demonstrate that MWCNTs exert evident influence as nucleating agents causing the rise of iPP and sPP crystallization temperature. Considerable retardation effect on iPP thermal oxidative degradation has been observed: the temperature of maximal weight loss rate rises by ~52 °C upon incorporating only 1.4 wt.% MWCNTs.     

Acylated and hydroxylated polyamides derived from l-tartaric acid

A series of polyamides 6,4 were prepared from 1,6-hexanediamine and active esters of 2,3-di-O-acylated l-tartaric acid by polycondensation in solution. Both O-alkoyl and O-benzoyl esters were used as hydroxyl protecting groups. The resulting acylated polytartaramides were found to be semicrystalline polymers with T_m between 100 and 200 °C and T_g slightly above 100 °C. Controlled hydrolysis of the ester side group led to the preparation of poly(hexamethylene l-tartaramide)s with different content in free hydroxyl groups. These polyamides continue being crystalline but their properties largely differ from those displayed by their parent acylated polymers.     

Removal of Phorbol Ester from Jatropha Seedcake Using Ozonation and Solar Irradiation

Jatropha curcas is a well-known source of non-edible vegetable oil that is being promoted as an energy source and high quality feedstock in biodiesel production, especially in developing countries. The potential that the resulting seedcake by-product from jatropha oil extraction (?70% by volume) could also be used as a component in animal feed raises the prospect that a commercially viable jatropha-based industry could be developed. To date, however, the use of jatropha seedcake in livestock feed formulation has been constrained by the presence of phorbol esters (PE), which are known promutagenic and toxic compounds, and by the inability to eliminate PE by cost-effective means. Using seedcake by-product collected from a commercial facility in West Africa that processes jatropha biodiesel, this study demonstrates cost-effective measures of eliminating PE from jatropha seedcake using a combination of solar irradiation and ozonation.     

Poly(butylene succinate) ionomers and their use as compatibilizers in nanocomposites

A series of low‐molecular‐weight poly(butylene succinate‐co‐glutarate‐co−2‐trimethylammonium chloride glutarate) terpolyester ionomers containing 35% mol of total glutarate units but varying in the content of charged units were synthesized by polycondensation at mild temperatures using a scandium catalyst. The terpolyester ionomers started to decompose at the temperatures of >175°C and all of them were semicrystalline and have glass transition temperature similar to poly(butylene succinate) (PBS). These terpolyesters were used to compatibilize the nanocomposites made of PBS‐cloisite (CL) prepared by melt extrusion. X‐ray diffraction revealed that an intercalated structure was present in these nanocomposites. The thermal properties of the three‐component mixtures did not differ substantially from those of PBS–CL but the mechanical properties were significantly improved by the addition of the ionomer, in particular tenacity. The beneficial effect afforded by the terpolyester ionomer was attributed to its ability for strengthening the binding between the PBS and the nanoclay. POLYM. COMPOS., 37:2603–2610, 2016. © 2015 Society of Plastics Engineers     

Marked osteoblastopenia and reduced bone formation in a model of multiple myeloma bone disease in severe combined immunodeficiency mice

Increased generation of reactive oxygen species (ROS) and low levels of antioxidants may cause morbidity in premature infants on supplemental oxygen. Glutathione (GSH)-dependent antioxidant systems protect against ROS, and regenerating GSH from GSH disulfide (GSSG) by the flavoenzyme GSH reductase (GR) is essential for the optimal function of this system. Previously, we have observed enhanced resistance to t-butyl hydroperoxide (t-BuOOH) in Chinese hamster ovary cells stably transfected with a vector (leader sequence GR [LGR]) for human GR cDNA that contained a functional synthetic mitochondrial targeting signal. The present studies were designed to investigate adenovirus-mediated gene transfer of LGR to H441 cells and resistance of such cells to t-BuOOH. Adenovirus-mediated transfection of H441 cells with LGR increased total GR activities more than 11-fold (mitochondria more than 10-fold and cytosolic more than 7-fold) and protected against t-BuOOH cytotoxicity, as indicated by lower fractional release of cellular lactate dehydrogenase (LDH) than was observed in wild-type untransfected cells (CON) or in cells transfected with a control gene (human manganese superoxide dismutase in the antisense orientation [DOS]) (*LGR 6.6 +/- 1.7; DOS 16 +/- 1.8; CON 16.6 +/- 0.7% LDH release). In addition, cells transfected with LGR retained higher GSH/GSSG ratios (*LGR 66 +/- 0.4; DOS 47 +/- 1; CON 52.6 +/- 2.3) and released less GSH + GSSG to the media in response to challenge with t-BuOOH (*LGR 0.05 +/- 0.01; DOS 0.08 +/- 0.01; CON 0.07 +/- 0.01 nmol/mg of protein) than did wild-type cells or cells transfected with a control vector, indicating an enhanced ability of the LGR cells to reduce GSSG formed in response to exposure to t-BuOOH. In conclusion, adenovirus-mediated gene transfer of LGR enhanced cellular GR activities and protected H441 cells from oxidant stresses.     

Interactions between Polymeric Dispersants and Calcium Silicate Hydrates

To better understand the mechanism of interaction between hydrating silicate-based cements and polymeric dispersants of the type used as "superplasticizers" in modern construction concretes, two different types of polymeric dispersant were added (at concentrations of 1 and 10 g/L) during the synthesis of calcium silicate hydrate (C-S-H) via the "pozzolanic reaction" in dilute slurries of lime and reactive silica, at Ca/Si ratios in the range of 0.66–1.50. Although both polymers gave degrees of adsorption of >79% in all cases studied, no significant structural modifications of the resulting C-S-H products were observed via X-ray diffraction or ²⁹Si magic angle spinning–nuclear magnetic resonance. These results differ from recent work in which it was shown that similar types of polymer could intercalate into the interlayers of C-S-H that was made using an alternative process. It is suggested that the process by which the C-S-H is formed may have a strong influence on whether C-S-H can intercalate polymers. This observation is relevant to understanding the fate of such polymers in concrete.     

Effect of combining the equal-channel angular hydroextrusion,direct hydroextrusion and drawing on properties of copper wire

Effect of combined processing by the equal-channel angular hydroextrusion (ECAH), direct hydroextrusion (HE) and drawing (D) on properties of copper wire is discussed in the paper. The technique has been for the first time employed for hardening lengthy copper rods and wire and reaching the ultimate tensile strength σ = 686 MPa and the elongation to failure δ = 2% in the 0.5 mm diameter copper wire. These contrast with σ = 556 MPa and δ = 1.4% resulted from processing without ECAH. Electrical conductivity of the highest strength wire produced with ECAH and conductivity of a hardened wire produced without ECAH differ negligibly.     

Experimental antitumour activity of S 16020-2 in a panel of human tumours

OBJECTIVE: To compare the effects of inhaled nitric oxide (NO) and extracorporeal membrane oxygenation (ECMO) on oxygenation, hemodynamics, and lymphatic drainage in an oleic acid lung injury model in sheep. DESIGN: Prospective, randomized study. SETTING: Animal research laboratory. ANIMALS: Thirty female sheep, weighing 35 to 40 kg. INTERVENTIONS: Acute lung injury was induced by central venous injection of oleic acid (0.5 mL/kg body weight). A chronic lymph fistula had been prepared through a right thoracotomy 3 days before the experiment. Animals were assigned randomly to the NO group (n = 14) or the ECMO group (n = 16). When a lung injury score of > 2.5 was achieved, the animals were given NO in dosage increments of 2, 5, 10, 20, and 40 parts per million (ppm), or placed on ECMO with an FIO2 of 0.21 (ECMO-21) and then 1.0 (ECMO-100) at the oxygenator. Mechanical ventilator parameters were kept constant to isolate the effects of NO and ECMO on systemic and pulmonary hemodynamics, cardiac output, oxygenation parameters, lymph/plasma protein ratio, and lymph flow. Measurements and calculations were performed after 1 hr at each individual step of NO concentration or FIO2. MEASUREMENTS AND MAIN RESULTS: In the ECMO group, PVRI and MPAP did not change and were significantly different from the NO group. In the NO group, there was a dose-dependent decrease in venous admixture, maximal at 10 ppm NO and decreasing from 40 +/- 6% to 23 +/- 10% (p < .05). This decrease was significantly different from the ECMO group, where there was no change. There was a significant increase in PaO2/FIO2 in the NO group, maximal at 10 ppm NO (84 +/- 11 to 210 +/- 90, p < .05), but a greater increase in PaO2/FIO2 on ECMO-21 (81 +/- 14 to 265 +/- 63) and a further increase on ECMO-100 (398 +/- 100) (p < .05). The lymph/plasma protein ratio remained unchanged in both groups after induction of lung injury by oleic acid. However, lymph flow decreased by 11 +/- 6% in the NO group, whereas it increased by 14 +/- 17% in the ECMO group (p < .05). CONCLUSIONS: In an oleic acid-induced sheep model of acute lung injury, there were significant differences between the effects of NO and ECMO on acute pulmonary hypertension, hypoxemia, hypercarbia, and lymph flow. NO significantly decreases pulmonary hypertension, whereas pulmonary hemodynamics were not substantially affected by ECMO. Both interventions reversed hypoxemia, but ECMO did so to a greater degree, and only ECMO improved hypercarbia. Only NO decreased lymph flow, possibly as an effect of decreased microvascular filtration pressure. This study did not attempt to evaluate the impact of these interventions on ventilatory requirements, barotrauma, or outcome. However, this model suggests that NO therapy may moderate pulmonary hypertension and improve lymph flow in acute lung injury. Clinical studies are needed to assess whether NO therapy might be beneficial in treatment of severe acute lung injury in older children and adults.