Nonisothermal Crystallization Kinetics of an Ethylene‐Vinyl‐Acetate: I Calorimetry Versus Rheology

The knowledge of the thermo‐mechanical response of polymers during crystallization is of seminal importance for process control and modeling. Among the other subtle findings, the crystallinity‐rheological simplicity, resembling the thermo‐rheological one, was frequently reported, based on the observation that the same amount of crystallinity induces the same rheological hardening to the polymer, regardless the crystallization conditions. The crystallization kinetics, which is a fundamental issue in polymer science, is investigated with differential scanning calorimetry (DSC) measurements. However, the poor agreement of calorimetric data with data coming from rheological investigation remains a debated issue. The crystallization kinetics of a commercial poly‐ethylene‐vinyl‐acetate copolymer (EVA) is here investigated both with DSC and rheological measurements. EVA is a nice model system since its melting point is below 100°C, thus allowing avoiding all the experimental shortcomings related to thermal degradation. We show that DSC and rheological crystallization data satisfactorily agree for the investigated copolymer and thus we conclude that all the discrepancies found in the literature must be principally due to experimental artifacts. Moreover, the observed agreement between DSC and rheological data confirms that the rheological hardening is proportional to the volume of crystallites only and not to the modality in which the crystallization takes place. POLYM. ENG. SCI., 59:2557–2563, 2019. © 2019 Society of Plastics Engineers     

Finding minimum and equitable risk routes for hazmat shipments

This paper deals with the generation of minimal risk paths for the road transportation of hazardous materials between an origin–destination pair of a given regional area. The main considered issue is the selection of paths that minimize the total risk of hazmat shipments while spreading the risk induced on the population in an equitable way. The problem is mathematically formulated, and two heuristic algorithms are proposed for its solution. Substantially, these procedures are modified versions of Yen's algorithm for the k-shortest path problem, which take into due consideration the risk propagation resulting from close paths and spread the risk equitably among zones of the geographical region in which the transportation network is embedded. Furthermore, a lower bound based on a Lagrangean relaxation of the given mathematical formulation is also provided. Finally, a series of computational tests, referring to a regional area is reported.     

Fractal Analysis and Simulation of Surface Roughness of Ceramic Particles for Composite Materials

An analytical model is presented for the determination of the fractal dimensions of particles which are widely used as reinforcement in nanocomposites. The model is used to characterize the surface irregularity or roughness. It was found that fractal dimensions of both the contour and surface of particles depend only on the relative particles size ratio between secondary particles and subunits. It is proposed that, in practical applications, the fractal dimension of a certain reinforcement particle can be obtained by a combination of this model and a state-of-the-art instrument that can determine the sizes of primary and secondary particles by image analysis. It is possible to relate the fractal dimension with the adhesion and other physical and chemical properties at the interface between particles and matrix.     

Myelodysplastic transformation in a case of essential thrombocythemia treated with pipobroman

A report of an 87-year-old Caucasian female with an extensive sebaceous carcinoma of the parotid gland is presented. The computed tomographic characteristics of this rare neoplasm are reported for the first time.     

Long-term results from MOPPEBVCAD chemotherapy with optional limited radiotherapy in advanced Hodgkin's disease

The purpose was to verify the 5-year results of the MOPPEBVCAD chemotherapy regimen with limited radiotherapy in relation to the promising preliminary data. Mechlorethamine, vincristine, procarbazine, prednisone, epidoxorubicin, bleomycin, vinblastine, lomustine, melphalan, and vindesine were delivered according to a schedule derived through hybridization, intensification, and shortening of the corresponding alternating CAD/MOPP/ABV regimen. Radiotherapy was restricted to sites of bulky involvement or to areas that responded incompletely to chemotherapy. This multicenter, controlled, nonrandomized trial involved 145 eligible patients. Radiotherapy was administered to 47 patients, 46 of whom were in complete remission after chemotherapy. Remissions were complete in 137 patients (94%), partial in 4 (3%), and null in the remaining 4. Tumor-specific, overall, relapse-free, and failure-free survival at 5 years were 0.89, 0.86, 0.82, and 0.78, respectively. Hematologic toxicity was considerable, whereas nonhematologic side effects were fully acceptable. Most of the unfavorable prognostic factors lost their clinical weight. Only age and lymphocyte depletion histologic type were statistically correlated with major follow-up endpoints; performance status and bone marrow involvement were subordinate to age. Seven patients developed a second cancer (including 3 myelodysplasias). MOPPEBVCAD with selected radiotherapy is a highly effective regimen in advanced Hodgkin's disease. Early and late toxicity are no more severe than what would be expected with other alternating or hybrid regimens. A comparison with ABVD, which is currently considered the standard regimen for advanced Hodgkin's disease, is needed.     

Opposite Modulation of Cell Migration by Distinct Subregions of Urokinase Connecting Peptide

Functional analysis of isolated protein domains may uncover cryptic activities otherwise missed. The serine protease urokinase (uPA) has a clear‐cut motogen activity that is catalytically independent and resides in its amino‐terminal growth factor domain (GFD, residues 1‐49) and connecting peptide region (CP, residues 132–158). To functionally dissect the CP region, we analysed the biological activity of two synthetic peptides corresponding to the N‐terminal [uPA‐(135–143), residues 135–143] and C‐terminal [uPA‐(144–158), residues 144–158] CP subregions. Most of the chemotactic activity of connecting peptide‐derived peptide (CPp, [uPA‐(135–158)]) for embryonic kidney HEK293/uPAR‐25 cells is retained by uPA‐(144–158) at nanomolar concentrations. In contrast, uPA‐(135–143) inhibits basal, CPp ‐, vitronectin‐ and fibronectin‐induced cell migration. Radioreceptor binding assays on intact HEK293 cells revealed that uPA‐(135–143) and uPA‐(144–158) are both able to compete with [¹²⁵I]‐CPp, albeit with different binding affinities. The consequences of phospho‐mimicking, S138E substitution, were studied using [138E]uPA‐(135–158) and [138E]uPA‐(135–143) peptides. Unlike CPp, [138E]uPA‐(135–158) and [138E]uPA‐(135–143) exhibit remarkable inhibitory properties. Finally, analysis of the conformational preferences of the peptides allowed to identify secondary structure elements exclusively characterising the stimulatory CPp and uPA‐(144–158) versus the inhibitory uPA‐(135–143), [138E]uPA‐(135–158) and [138E]uPA‐(135–143) peptides. In conclusion, these data shed light on the cryptic activities of uPA connecting peptide, revealing the occurrence of two adjacent regions, both competing for binding to cell surface but conveying opposite signalling on cell migration.     

Synthesis and characterization of electrically conductive polyethylene-supported graphene films

We describe a simple mechanical approach for low-density polyethylene film coating by multilayer graphene. The technique is based on the exfoliation of nanocrystalline graphite (few-layer graphene) by application of shear stress and allows to obtain thin graphene layers on the plastic substrate. We report on the temperature dependence of electrical resistance behaviors in films of different thickness. The experimental results suggest that the semiconducting behavior observed at low temperature can be described in the framework of the Efros-Shklovskii variable-range-hopping model. The obtained films exhibit good electrical conductivity and transparency in the visible spectral region.

PACS

72.80.Vp; 78.67.Wj; 78.66.Qn; 85.40.Hp