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81.
Emanuela Tamburri Valeria Guglielmotti Silvia Orlanducci Maria Letizia Terranova Daniela Sordi Daniele Passeri Roberto Matassa Marco Rossi 《Polymer》2012,53(19):4045-4053
The detonation nanodiamond is a novel versatile nanomaterial with tunable properties and surface chemistry. In this work, we report on a template-free method to synthesize polyaniline based nanocomposite fibers during a chemical oxidative precipitation polymerization where the cooperative interactions between nanodiamond and polyaniline nucleates trigger the final morphology of the nanocomposite. FE–SEM and TEM observations evidence the prominent growth of fibril-like structures assembled in 2-D networks of tightly woven, partially oriented fibers. Optical and Raman spectroscopy and X-ray diffraction analyses reveal that the polymer chains are in a protonated emeraldine form and organize themselves in a highly ordered 3-D spatial arrangement. Conductivity measurements performed on isolated fibers by a conductive tip of an AFM apparatus highlight that the diamond filler does not affect the conductive properties of the polyaniline matrix while increases the thermal stability of the polymer as confirmed by TGA studies. 相似文献
82.
Daniela Ubiali Carla D. Serra Immacolata Serra Carlo F. Morelli Marco Terreni Alessandra M. Albertini Paolo Manitto Giovanna Speranza 《Advanced Synthesis \u0026amp; Catalysis》2012,354(1):96-104
Purine nucleoside phosphorylase (PNP) from Aeromonas hydrophila encoded by the deoD gene has been over‐expressed in Escherichia coli, purified, characterized about its substrate specificity and used for the preparative synthesis of some 6‐substituted purine‐9‐ribosides. Substrate specificity towards natural nucleosides showed that this PNP catalyzes the phosphorolysis of both 6‐oxo‐ and 6‐aminopurine (deoxy)ribonucleosides. A library of nucleoside analogues was synthesized and then submitted to enzymatic phosphorolysis as well. This assay revealed that 1‐, 2‐, 6‐ and 7‐modified nucleosides are accepted as substrates, whereas 8‐substituted nucleosides are not. A few transglycosylation reactions were carried out using 7‐methylguanosine iodide ( 4 ) as a D ‐ribose donor and 6‐substituted purines as acceptor. In particular, following this approach, 2‐amino‐6‐chloropurine‐9‐riboside ( 2c ), 6‐methoxypurine‐9‐riboside ( 2d ) and 2‐amino‐6‐(methylthio)purine‐9‐riboside ( 2g ) were synthesized in very high yield and purity. 相似文献
83.
Marindia Decol Wagner M. Pachekoski Elisa H. Segundo Luís Antônio Pinheiro Daniela Becker 《应用聚合物科学杂志》2020,137(20):48711
In this study, the effects of processing conditions through different mixing sequences were used to analyze the factors, which could influence the hybrid filler selective localization in an immiscible polymer blend and how localization can influence the rheological and thermal properties. Different selective localizations were observed depending on the mixing sequence used when the hybrid filler was added. Notably, nanoparticles can interact with each other, which favor a synergy between them and alters, besides the localization, the dispersion state, or can interact with one polymer phase, and also alter the nanoparticles' selective localization. An improvement in rheological properties was observed in the hybrid nanocomposite in which there was interaction between the nanoparticles, favoring the hexagonal boron nitride exfoliation. On the other hand, for the storage modulus and degree of crystallinity, the sharpest increase occurred in the hybrid nanocomposite in which the nanoparticles could interact preferably with one polymer phase. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48711. 相似文献
84.
Vanya B. Kurteva Liudmil M. Antonov Daniela V. NedeltchevaAurélien Crochet Katharina M. FrommRositsa P. Nikolova Boris L. ShivachevMaya S. Nikiforova 《Dyes and Pigments》2012,92(3):1266-1277
A series of azo dyes, possessing amide fragments with restricted flexibility tethered to 4-(phenyldiazenyl)naphthalen-1-ol, was obtained from 1-hydroxy-2-naphthoic acid by subsequent conversion to amides and diazo coupling. It was shown that the position of the tautomeric equilibrium in solution strongly depends on the solvent in both UV and NMR concentration scale. The compounds exist as pure enol forms in chloroform and hydrocarbons, while in polar solvents (acetone, acetonitrile, alcohols) a tautomeric mixture is observed. According to the quantum-chemical calculations the aggregation of the keto tautomer is the possible reason for this shift in the position of the tautomeric equilibrium. To support the theoretical predictions, it was found that from acetone the keto form crystallizes as a dimer with hydrogen bonding between N1-H in the one molecule and amide CO in the other forming a three-dimensional structure. The importance of the side-chain nitrogen atom on the dimer formation was confirmed by solution and solid state study of 4-(phenyldiazenyl)-2-acetylnaphthalen-1-ol. The results indicate that the new azo-dyes obtained could be suitable candidates for switching and sensing applications in non-polar solvents. 相似文献
85.
Letícia Helena Gasparini Paes Teresa Tromm Steffen Daniela Becker 《Polymer Engineering and Science》2020,60(6):1333-1342
Multiwall carbon nanotubes (CNT) or montmorillonite clay (MMT-30B) were added to a poly(hexamethylene isophthalamide-co-terephthalamine) (an amorphous polyamide - aPA) and styrene-ethylene/butylene-styrene graphitized with maleic anhydride (SEBS) blend, in different concentrations, in order to investigate the morphology, thermal properties and flammability behavior. Different nanoparticle localizations in the phase blend were observed through transmission electronic microscopy. CNT nanoparticles are localized in SEBS phase, and MMT-30B nanoparticles in aPA phase. No significant changes were observed on transition temperatures and thermal stability with both nanoparticle additions. However, a slight increase on storage modulus for clay nanocomposites and a slight reduction for carbon nanotube nanocomposites were observed, due to their different phase localizations. Regarding flammability, CNT nanocomposites showed better performance as a flame retardant when compared to samples with MMT-30B. Although the MMT-30B nanocomposites could not be classified according to the UL-94 criteria, no dripped flaming particles were observed, due to the a char barrier formation on the polymer surface. The CNT nanocomposites were classified according to the UL-94 criteria as V-2. The CNT's selective localization on the SEBS phase decreases its heat-release rate, but no interconnected network structure was formed in the matrix to suppress the dripping flaming particles. 相似文献
86.
Elisa Rumi Chiara Trotti Daniele Vanni Ilaria Carola Casetti Daniela Pietra Emanuela SantAntonio 《International journal of molecular sciences》2020,21(23)
Among classical BCR-ABL-negative myeloproliferative neoplasms (MPN), primary myelofibrosis (PMF) is the most aggressive subtype from a clinical standpoint, posing a great challenge to clinicians. Whilst the biological consequences of the three MPN driver gene mutations (JAK2, CALR, and MPL) have been well described, recent data has shed light on the complex and dynamic structure of PMF, that involves competing disease subclones, sequentially acquired genomic events, mostly in genes that are recurrently mutated in several myeloid neoplasms and in clonal hematopoiesis, and biological interactions between clonal hematopoietic stem cells and abnormal bone marrow niches. These observations may contribute to explain the wide heterogeneity in patients’ clinical presentation and prognosis, and support the recent effort to include molecular information in prognostic scoring systems used for therapeutic decision-making, leading to promising clinical translation. In this review, we aim to address the topic of PMF molecular genetics, focusing on four questions: (1) what is the role of mutations on disease pathogenesis? (2) what is their impact on patients’ clinical phenotype? (3) how do we integrate gene mutations in the risk stratification process? (4) how do we take advantage of molecular genetics when it comes to treatment decisions? 相似文献
87.
Stefano J. Mandriota Mirna Tenan Adeline Nicolle Julia D. Jankowska Paolo Ferrari Jean-Christophe Tille Mary-Anne Durin Catherine M. Green Sebastien Tabruyn Daniela Moralli Andr-Pascal Sappino 《International journal of molecular sciences》2020,21(23)
Genomic instability is generally considered as a hallmark of tumorigenesis and a prerequisite condition for malignant transformation. Aluminium salts are suspected environmental carcinogens that transform mammary epithelial cells in vitro through unknown mechanisms. We report here that long-term culture in the presence of aluminium chloride (AlCl3) enables HC11 normal mouse mammary epithelial cells to form tumours and metastases when injected into the syngeneic and immunocompetent BALB/cByJ strain. We demonstrate that AlCl3 rapidly increases chromosomal structural abnormalities in mammary epithelial cells, while we failed to detect direct modulation of specific mRNA pathways. Our observations provide evidence that clastogenic activity—a well-recognized inducer of genomic instability—might account in part for the transforming abilities of aluminium in mammary epithelial cells. 相似文献
88.
Norma Daniela González Enriquez Rosalba Patiño-Herrera Rafael Catarino-Centeno Gabriela Palestino Armando Almendárez Camarillo Elías Pérez 《Polymer Engineering and Science》2023,63(1):219-229
Concerned about environmental pollution, and aware of the comfort that polyethylene provides for daily human life, this work sought to replace a percentage of high-density polyethylene (HDPE) with human or bovine hair. Hair is natural, abundant, light weight, non-toxic, and disposed of as garbage. The main disadvantage of natural composites is the interfacial adhesion. To increase the interfacial adhesion between hair and HDPE, stearic acid or oleic acid was chemically anchored on the hair surface, which leads to an improved contact angle hysteresis and hydrophobicity. Dynamic-mechanical properties of the composites were investigated focusing on the type of carboxylic acid used (stearic or oleic acid), hair length, hair type (human or bovine) and amount of hair used in the composite. Taking 40°C as a reference, using 15% of hair with a length of 1 ± 0.15 mm, the highest storage modulus value was obtained with HDPE with human hair modified with oleic acid, exceeding the value of the storage modulus of HDPE by 67.64%. Increasing storage modulus on composites indicates of interfacial interaction and chemical affinity improvement between hair and polyethylene. 相似文献
89.
Daniela BianchiniKátia Messias Bichinho João Henrique Zimnoch dos Santos 《Polymer》2002,43(10):2937-2943
The effect of Al content on MAO-modified silicas was evaluated on catalyst activity, on polymer properties and on residual metal content in the resulting polyethylenes. MAO-modified silicas were prepared by impregnating MAO toluene solutions in concentration range between 0.5 and 20.0 wt% Al/SiO2. Commercial MAO-modified silica (Witco) containing 24.4 wt% Al/SiO2 was used for comparative reasons. The resulting modified-silicas were employed as supports for grafting (nBuCp)2ZrCl2. Using external MAO as cocatalyst (Al/Zr=2000) no difference in catalyst activity was observed. Nevertheless, for Al/Zr=500, catalyst activities were shown to be higher for supported zirconocene systems containing 0.0-2.0 wt% Al/SiO2 range. According to DSC analysis, one Tm peak was detected for polymer obtained with catalyst prepared with 0.5 wt% Al/SiO2 (135 °C), but two Tm peaks were observed for polymers obtained with catalysts prepared with 10.0 wt% Al/SiO2 (136 and 141 °C) and 20.0 wt% Al/SiO2 (133 and 141 °C). 相似文献
90.
Simonetta Tuti Franco Pepe Daniela Pietrogiacomi Valerio Indovina 《Catalysis Today》2002,75(1-4):373-378
FeOx/ZrO2 samples, prepared by impregnation with Fe(NO3)3, were characterised by means of DRS, XRD, FTIR, redox cycles and volumetric CO adsorption. Volumetric CO adsorption, combined with FTIR, showed that 45% of iron in the sample containing 2.8 Fe atoms nm−2 was capable of forming iron carbonyls. DRS evidenced Fe2O3 on samples with Fe-content≥2.8 atoms nm−2. The selective catalytic reduction of NO with C3H6 in the presence of O2 was studied with a reactant mixture containing NO=4000 ppm, C3H6=4000 ppm, O2=2%. The dependence on iron-content suggests that only isolated iron, prevailing in dilute FeOx/ZrO2, is active for NO reduction, whereas iron on the surface of small oxide particles, prevailing in concentrated FeOx/ZrO2, is active for C3H6 combustion. 相似文献