Viscoelastic properties and morphological characteristics of polymer‐modified bitumen blends

The state of dispersion, the viscoelastic properties and the mechanical properties (such as Young's modulus, ductibility, penetration, and Fraas breaking point) of polymer‐modified bitumen are investigated. Bitumen was modified with low‐density polyethylene from processed bags (PE_bags) and styrene‐butadiene random block copolymer (SBR). The blends were characterized by optical microscopy, dynamic mechanical thermal analysis (DMTA), and other conventional methods. Photomicrographs indicated that different morphologies were obtained; PE_bags gave dispersions with almost spherical polymer particles; whereas in the case of SBR, fibrillar domains were observed. DMTA measurements indicated significant changes of the storage and loss moduli of modified bitumen; depending on the polymer content in the bitumen matrix, these values were three to four times higher compared with neat bitumen. Blends with SBR showed a significantly increased resistance to cracking at low temperatures due to decrease of the glass transition temperature from ?14 to ?34°C. Contrary, PE_bags gave better results at higher temperatures where as a result of the increased resistance to permanent deformation the softening point of modified bitumen was shifted from 52 to 73°C. It was also investigated the influence of mixtures of PE_bags/SBR on the properties of bitumen as function of the composition and ratio between PE_bags and SBR. It was found that the best improvement in deformation resistance, permanent deformation, and cracking of bitumen was achieved with the addition of PE_bags/SBR mixture as the rubber increased the bitumen properties at low temperatures and the polyolefin at high temperatures. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Evaluation of the Effectiveness of New Compatibilizers Based on EBAGMA‐LDPE and EBAGMA‐PET Masterbatches for LDPE/PET Blends

The present paper is aimed to evaluate the efficiency of two masterbatches, i.e., EBAGMA/LDPE (MB1) and EBAGMA/PET (MB2) with 50/50 w/w composition, prepared by melt mixing and used as new compatibilizers for blends of LDPE/PET. The morphology, the mechanical and the thermal properties of LDPE/PET/MB1 and LDPE/PET/MB2 ternary blends have been investigated. Morphological investigation by SEM of LDPE/PET/MB1 ternary blends showed a finer dispersion of PET in LDPE matrix with a better interfacial adhesion compared to those of both LDPE/PET/MB2 and binary LDPE/PET blends. The results also indicated a substantial improvement in both elongation at break and impact strength, while the Young's modulus decreased. Moreover, the thermal properties showed a decrease of the crystallization phenomena of PET in LDPE/PET/MB1 blend, thus confirming the good dispersion of PET particles into the continuous phase of LDPE matrix, leading to the conclusion that MB1 could be an efficient compatibilizer for LDPE/PET system.

     

Extracting High-Level Information from Location Data: The W4 Diary Example

Services for mobile and pervasive computing should extensively exploit contextual information both to adapt to user needs and to enable autonomic behavior. To fulfill this idea it is important to provide two key tools: a model supporting context-data representation and manipulation, and a set of algorithms relying on the model to perform application tasks. Following these lines, we first describe the W4 context model showing how it can represent a simple yet effective framework to enable flexible and general-purpose management of contextual information. In particular, we show the model suitability in describing user-centric situations, e.g., describing situations in terms of where a user is located and what he is doing. Then, we illustrate a set of algorithms to semantically enrich W4 represented data and to extract relevant information from it. In particular, starting from W4 data, such algorithms are able to identify the places that matter to the user and to describe them semantically. Overall, we show how the context-model and the algorithms allow to create an high-level, semantic and context-aware diary-based service. This service meaningfully collects and classifies the user whereabouts and the places that the user visited.

Cyclic RGD‐Containing Functionalized Azabicycloalkane Peptides as Potent Integrin Antagonists for Tumor Targeting

Vitronectin receptors α _v β ₃ and α _v β ₅ have emerged as potential therapeutic targets for the treatment of osteoporosis, restenosis, ocular disease, tumor‐induced angiogenesis, metastasis, and sickle‐cell anemia. Among a collection of compounds, a new potent integrin antagonist was synthesized, and its binding toward the α_vβ₃ and α_vβ₅ receptors was evaluated. This molecule is a suitable candidate as a vector for therapeutics and diagnostics.

     

Interaction of Artemisinins with Oxyhemoglobin Hb–FeII,Hb–FeII,CarboxyHb–FeII,Heme–FeII,and Carboxyheme FeII: Significance for Mode of Action and Implications for Therapy of Cerebral Malaria

In line with the enhancement of antimalarial activities of the current clinical artemisinins against parasites cultured under CO, the artemisinins are unaffected in vitro by carboxyhemoglobin (CO–Hb–Fe^II) or CO–heme–Fe^II, but are competitively decomposed by Hb–Fe^II or heme–Fe^II. In the latter case, the heme studies are greatly facilitated by solubilization of the heme in aqueous medium by use of arginine. None of the Hb species has an appreciable effect on artemisone, or on other aminoartemisinins, and antimalarial activities are either less affected or remain essentially unchanged against parasites cultured under standard microaerophilic conditions or under CO. The findings not only indicate that artemisinins do not require Hb–Fe^II or heme–Fe^II for promotion of antimalarial activity, but are also important in relation to the therapy of severe/complicated or cerebral malaria.     

Deciphering the Electroluminescence Behavior of Silver(I)‐Complexes in Light‐Emitting Electrochemical Cells: Limitations and Solutions toward Highly Stable Devices

Ionic transition‐metal complexes based on silver(I) metal core (Ag‐iTMCs) represent an appealing alternative to other iTMCs in solid‐state lighting owing to (i) their low cost and well‐known synthesis, (ii) the tunable bandgap, and (iii) the highly efficient photoluminescence. However, their electroluminescence behavior is barely studied. Herein, the archetypal green‐emitting Ag‐iTMCs, namely [Ag(4,4′‐dimethoxy‐2,2′‐bipyridine)(Xantphos)]X (X = BF₄, PF₆, and ClO₄), are thoughtfully investigated, revealing their electroluminescent features in light‐emitting electrochemical cells (LECs). Despite optimizing device fabrication and operation, luminance of 40 cd m^?2, efficacy of 0.2 cd A^?1, and a very poor stability of 30 s are achieved. This outcome encourages the comprehensive study of the degradation mechanism combining electrochemical impedance spectroscopy, X‐ray diffraction, and cyclic voltammetry techniques. These results point out the irreversible formation of silver nanoclusters under operation strongly limiting the device performance. As such, LECs are further optimized by (i) changing the counterions (PF₆^? and ClO₄^?) and (ii) decoupling electron injection and exciton formation using a double‐layered architecture. The synergy of both approaches leads to a broad exciplex‐like whitish electroluminescence emission (x/y CIE of 0.40/0.44 and color rendering index of 85) with an outstanding improved stability of ≈4 orders of magnitude (>80 h) without losing brightness (35 cd m^?2).     

Modifications in chromatin morphology and organization during sheep oogenesis

This research has been designed to study the major events of nuclear remodeling that characterize sheep oocytes during the early stage of folliculogenesis (transition from preantral to antral stage). In particular, the modifications in large-scale chromatin configuration, the global DNA methylation, and the process of telomere elongation have been investigated as crucial events of oocyte nuclear maturity. In addition, the spatio-temporal distribution of the major enzymes involved in DNA methylation, the DNA methyltransferase 1 (Dnmt1), and in telomere elongation, telomerase catalytic subunit (TERT), have been described. To these aims, the nuclei of isolated oocytes were investigated using immunocytochemistry and Q-FISH analyses. In absence of preliminary information, these nuclear determinants were compared with those of fully competent germ cells obtained from medium and preovulatory antral follicles. The nuclei of sheep oocytes acquired a condensed chromatin configuration, stable high levels of global DNA methylation, and a definitive telomere length already in the majority of late growing stage oocytes (110 microm) derived from early antral follicles. In addition, while the process of methylation resulted strictly related to oocyte diameter, the telomeric program appeared to be highly chromatin configuration-dependent. The translocation of Dnmt1 and TERT from the nucleus to the cytoplasm in the oocytes derived from early antral follicles seems to confirm the definitive chromatin asset of these germ cells. In conclusion, changes in large-scale chromatin structure, epigenesis, and telomere size in the sheep are established prior to oocyte acquires the ability to resume meiosis.     

Shape and orientation of revolution surfaces from contours and reflections

The reconstruction of shape and pose of a solid of revolution from a single image is addressed. When there is no cross section, whose contour can be extracted from the image, this problem is underdeterminate; therefore, a reflection from a point light source is used in addition to the contour information. Under the orthoperspective hypothesis, when axial-symmetric reflection model is applicable, the reflection appears along a meridian of the revolution surface. This fact is exploited in order to determine both the orientation of the revolution axis and the shape of the profile. Promising experimental results have been obtained.