Search results for " engineering"
showing 10 items of 38291 documents
Polypropylene/polyhedral oligomeric silsesquioxane nanocomposites – study of free volumes, crystallinity degree and mass flow rate
2016
Nanokompozyty polipropylen/poliedryczne oligomeryczne silseskwioksany (PP/POSS) przygotowano metodą mieszania w stanie stopionym polimeru. Wpływ struktury oraz ilości zastosowanych nanonapełniaczy POSS na objętości swobodne w polipropylenie określono z zastosowaniem spektroskopii czasów życia pozytonów (PALS). Ustalono zależności pomiędzy parametrami PALS: czasem życia o-Ps (τ3) i natężeniem (I3) składowej o-Ps oraz wartościami stopnia krystaliczności (Xc ) i masowego wskaźnika szybkości płynięcia (MFR) badanych materiałów. Obecność nanonapełniaczy POSS wpłynęła na liczbę i rozmiary objętości swobodnych w polimerze, co spowodowało zmianę mikrostruktury osnowy polipropylenowej. Wraz ze zwięk…
Platformed Interactions: How Social Media Platforms Relate to Candidate–Constituent Interaction During Finnish 2015 Election Campaigning
2020
Interaction between candidates and constituents via social media is a well-studied domain. The article takes this research further through a synthesis with platform studies, emerging scholarship that applies a critical perspective to the role of digital platforms in society. Examination of candidate–constituent interaction via Twitter and Facebook during the 2015 Finnish parliamentary elections revealed that the types of interaction differ between the two platforms: Facebook was used for formal campaigning and for praising and expressing support, while Twitter was utilized for information and for seeking and sharing opinions. An additional finding is that interaction approaches may be plat…
Knowledge Management in the Project Life Cycle - Initial Research on Polish Smes
2014
Abstract Contemporary organizations run their activities in an environment, which might be defined as fully uncertain and turbulent. Due to variations that occur in the surrounding environment, an increased attention of management practitioners and theoreticians is paid to new management concepts frequently in an integrated version. The authors express a deep belief that consolidation of approaches to project management and knowledge management constitutes a response to challenge for modern organizations. Research into the issue was based on an attempt to determine significance of the knowledge management issue in a life of projects performed by Polish small and medium-sized enterprises (SM…
La territorialisation des politiques scolaires : l'exemple des collèges du bassin de Gap
2006
ACL; International audience; Le bassin de Gap connaît un accroissement démographique en milieu périurbain, ce qui nécessite l'analyse de la carte scolaire afin de créer de nouveaux collèges. Ce bassin de population, marqué par des contraintes fortes, est un véritable espace vécu dans le sens où il est structuré par des aires de recrutement résultant des pratiques spatiales des élèves et de leurs familles. Une étude approfondie des structures et des dynamiques spatiales de ce bassin permet de tirer quelques leçons quant au fonctionnement d'un territoire scolaire.
Sustainable urban transport policy in emerging countries – case study of Mexico
2015
Negatywne efekty zewnętrzne transportu stanowią bolączkę współczesnych miast, niekorzystnie oddziałując na procesy rozwoju społeczno-gospodarczego. Problemy te są widoczne nie tylko w krajach wysoko czy średnio rozwiniętych – w ogromnym stopniu borykają się z nimi wielomilionowe i wielkopowierzchniowe metropolie, które z kolei są charakterystyczne głównie dla krajów wschodzących, jak np. Chiny, Indie, Brazylia czy Meksyk. Celem artykułu jest przedstawienie wybranych aspektów polityki zrównoważonego rozwoju transportu w stolicy jednego z tych krajów – Meksyku. Autorka starała się również odpowiedzieć na pytanie, w jaki sposób specyficzne uwarunkowania lokalne o różnym charakterze determinują…
Effects of Polyacrylic Acid Pre-Treatment on Bonded-Dentine Interfaces Created with a Modern Bioactive Resin-Modified Glass Ionomer Cement and Subjec…
2018
Objectives: Resin-modified glass ionomer cements (RMGIC) are considered excellent restorative materials with unique therapeutic and anti-cariogenic activity. However, concerns exist regarding the use of polyacrylic acid as a dentine conditioner as it may influence the bonding performance of RMGIC. The aim of this study was to evaluate the effect of different protocols for cycling mechanical stress on the bond durability and interfacial ultramorphology of a modern RMGIC applied to dentine pre-treated with/without polyacrylic acid conditioner (PAA). Methods: The RMGIC was applied onto human dentine specimens prepared with silicon-carbide (SiC) abrasive paper with or without the use of a PAA c…
Design of New Polyaspartamide Copolymers for siRNA Delivery in Antiasthmatic Therapy
2020
Here, a novel protonable copolymer was realized for the production of polyplexes with a siRNA (inhibitor of STAT6 expression in asthma), with the aim of a pulmonary administration. The polycation was synthesized by derivatization of &alpha
Acid-Labile Surfactants Based on Poly(ethylene glycol), Carbon Dioxide and Propylene Oxide: Miniemulsion Polymerization and Degradation Studies
2017
Partially degradable, nonionic AB and ABA type di- and triblock copolymers based on poly(propylene carbonate) and poly(ethylene glycol) blocks were synthesized via immortal copolymerization of carbon dioxide and propylene oxide, using mPEG or PEG as a macroinitiator, and (R,R)-(salcy)-CoOBzF5 as a catalyst in a solvent-free one-pot procedure. The amphiphilic surfactants were prepared with molecular weights (Mn) between 2800 and 10,000 g·mol−1 with narrow molecular weight distributions (1.03–1.09). The copolymers were characterized using 1H-, 13C- and DOSY-NMR spectroscopy and size exclusion chromatography (SEC). Surface-active properties were determined by surface tension measurements (crit…
Improvements in Rational Design Strategies of Inulin Derivative Polycation for siRNA Delivery.
2016
The advances of short interfering RNA (siRNA)-mediated therapy provide a powerful option for the treatment of many diseases, including cancer, by silencing the expression of targeted genes involved in the progression of the pathology. On this regard, a new pH-responsive polycation derived from inulin, Inulin-g-imidazole-g-diethylenetriamine (INU-IMI-DETA), was designed and employed to produce INU-IMI-DETA/siRNA "Inulin COmplex Nanoaggregates" (ICONs). The experimental results showed that INU-IMI-DETA exhibited strong cationic characteristics and high solubility in the pH range 3-5 and self-aggregation triggered by pH increase and physiological salt concentration. INU-IMI-DETA showed as well…
Halogen-Bonded Co-Crystals of Aromatic N-oxides : Polydentate Acceptors for Halogen and Hydrogen Bonds
2017
The C-ethyl-2-methylresorcinarene (1) forms 1:1 in-cavity complexes with aromatic N,N′-dioxides, only if each of the aromatic rings has an N−O group. The structurally different C-shaped 2,2′-bipyridine N,N′-dioxide (2,2′-BiPyNO) and the linear rod-shaped 4,4′-bipyridine N,N′-dioxide (4,4′-BiPyNO) both form 1:1 in-cavity complexes with the host resorcinarene in C4v crown and C2v conformations, respectively. In the solid state, the host–guest interactions between the 1,3-bis(4-pyridyl)propane N,N′-dioxide (BiPyPNO) and the host 1 stabilize the unfavorable anti-gauche conformation. Contrary to the N,N′-dioxide guests, the mono-N-oxide guest, 4-phenylpyridine N-oxide (4PhPyNO), does not form an…