831 research outputs found
Temperature-dependent structural changes on DDAB surfactant assemblies evidenced by energy dispersive X-ray diffraction and dynamic light scattering
No full textCationic amphiphile DDAB (dimethyl-dioctadecyl-ammonium-bromide) can spontaneously form water-dispersed and solid supported mimicking biomembrane structures as well as valuable DNA delivery vehicles whose shape, stability and transfection efficiency can be easily optimized on varying temperature, water content and chemical composition. In this framework, disclosing the thermotropic behavior of DDAB assemblies can be considered as an essential step in conceiving and developing new non-viral vector systems.Our work has been focused primarily on understanding the mesophase structure of silicon supported DDAB thin film on varying temperature at constant relative humidity by energy dispersive X-ray diffraction (EDXD). Diffraction results have then been employed in providing a more comprehensive dynamic light scattering (DLS) analysis of corresponding thermotropic water dispersed vesicles made up of DDAB alone and in combination with helper lecithin DOPC (1,2-dioleoyl-sn-glycero-3-phosphatidylcholine) liposomes.We found that above 55 degrees C silicon-supported DDAB films undergo a significant thinning effect, whilst DDAB-water vesicles exhibit a reduction in size polydispersity. Upon cooling to 25 degrees C a distinct silicon supported DDAB mesophase, exhibiting a relative humidity-dependent spacing, has been pointed out, and modeled in terms of a lyotropic metastable gel-crystalline phase.DDAB/DOPC-water vesicles show a temperature-dependent switching in size distribution, leading to promising biomedical applications. (C) 2012 Elsevier B.V. All rights reserved
L’istruzione politico-ideologica in Cina. Il difficile rapporto tra il partito e gli studenti
No full textPeople and heritage in low-urbanized settings. An onging study of accessibility to the iglesiente area (Italy)
No full textMorphometric analysis of osteonal architecture in bones from healthy young human male subjects using scanning electron microscopy.
No full textThe shape and structure of bones is a topic that has been studied for a long time by morphologists and biologists with the goal of explaining the laws governing their development, aging and pathology. The osteonal architecture of tibial and femoral mid-diaphyses was examined morphometrically with scanning electron microscopy in four healthy young male subjects. In transverse sections of the mid-diaphysis, the total area of the anterior, posterior, lateral and medial cortex sectors was measured and analysed for osteonal parameters including osteon number and density, osteon total and bone area and vascular space area. Osteons were grouped into four classes including cutting heads (A), transversely cut osteons (B), longitudinally cut osteons (C) and sealed osteons (D). The morphometric parameters were compared between the inner (endosteal) and outer (periosteal) half of the cortex. Of 5927 examined osteons, 24.4% cutting heads, 71.1% transversely cut osteons, 2.3% longitudinally cut osteons and 2.2% sealed osteons were found. The interosteonic bone (measured as the area in a lamellar system that has lost contact with its own central canal) corresponded to 51.2% of the endosteal and 52.4% of the periosteal half-cortex. The mean number of class A cutting heads and class B osteons was significantly higher in the periosteal than in the endosteal half-cortex (P < 0.001 and P < 0.05, respectively), whereas there was no significant difference in density. The mean osteon total area, osteon bone area and vascular space area of both classes A and B were significantly higher (P < 0.001 for all three parameters) in the endosteal than in the periosteal half-cortex. The significant differences between the two layers of the cortex suggest that the osteoclast activity is distributed throughout the whole cortical thickness, with more numerous excavations in the external layer, but larger resorption lacunae closer to the marrow canal. A randomly selected population of 109 intact class B osteons was examined at higher magnification (350×) to count osteocyte lacuna and to analyse their relationship with osteon size parameters. The distribution frequency of the mean number of osteocyte lacunae increased with the increment in the sub-classes of osteon bone area, whereas the density did not show significant differences. The number of osteocyte lacunae had a direct correlation with the osteon bone area and the mean osteon wall thickness, as well as the mean number of lamellae. The osteocyte lacunae density showed an inverse relationship. These data suggest a biological regulation of osteoblast activity with a limit to the volume of matrix produced by each cell and proportionality with the number of available cells in the space of the cutting cone (total osteon area). The collected data can be useful as a set of control parameters in healthy human bone for studies on bone aging and metabolic bone diseases
132) Silicon supported lipid–DNA thin film structures at varying temperature studied by energy dispersive X-ray diffraction and neutron reflectivity
No full textNon-viral gene transfection by means of lipid-based nanosystems, such as solid supported lipid assemblies,
is often limited due to their lack of stability and the consequent loss of efficiency. Therefore not only a detailed thermo-lyotropic study of these DNA–lipid complexes is necessary to understand their
interaction mechanisms, but it can also be considered as a first step in conceiving and developing new transfection biosystems.
The aim of our study is a structural characterization of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine
(DOPC)–dimethyl-dioctadecyl-ammonium bromide (DDAB)–DNA complex at varying temperature using the energy dispersive X-ray diffraction (EDXD) and neutron reflectivity (NR) techniques.
We have shown the formation of a novel thermo-lyotropic structure of DOPC/DDAB thin film selforganized in multi-lamellar planes on (1 0 0)-oriented silicon support by spin coating, thus enlightening its ability to include DNA strands. Our NR measurements indicate that the DOPC/DDAB/DNA complex forms temperature-dependent structures. At 65 ◦C and relative humidity of 100% DNA fragments are buried between single lamellar leaflets constituting the hydrocarbon core of the lipid bilayers. This finding supports the consistency of the hydrophobic interaction model, which implies that the coupling between
lipid tails and hypo-hydrated DNA single strands could be the driving force of DNA–lipid complexation.
Upon cooling to 25 ◦C, EDXD analysis points out that full-hydrated DOPC–DDAB–DNA can switch in a different metastable complex supposed to be driven by lipid heads–DNA electrostatic interaction. Thermotropic
response analysis also clarifies that DOPC has a pivotal role in promoting the formation of our observed thermophylic silicon supported lipids–DNA assembly
Cocco, M.T., Congiu, C., Maccioni, A., Onnis, V Convenient synthesis of 4-amino-7-(dialkylamino)pyrido[2,3-d]pyrimidines from polysubstituted pyridines
No full textA convenient synthesis of 4-amino-7-(dialkylamino)pyrido[2,3-d]pyrimidines via cyclization of functionalized pyridines is reported. The preparation of the starting pyridines from 3-amino-3-(dialkylaraino)propene-nitriles and ethoxymethylenemalononitrile is described
Regulation, Innovation, and Systems Integration: Evidence from the EU
No full textEnergy systems integration (ESI) provides a holistic view of the electricity, gas, and heat sectors, which allows the identification and delivery of system solutions that lead to an overall cost efficiency while granting the reliability of the energy system. In this paper, we search for evidence of investments in ESI in the EU to assess whether policymakers are incentivizing its adoption adequately. To do so, we examine how innovation is being fostered in the energy sector in six EU countries by looking at the incentives provided by each country’s regulatory system. We look for
evidence on investments in ESI-enabling technologies or ESI projects. We find a variety of approaches towards incentivizing innovation, which range from regulation-driven to government-driven ones. Preferences for different technologies emerge on a per-country basis. Nevertheless, what appears as most striking is the low level of investments throughout the six countries, both for ESI-enabling technologies and ESI projects. Although ESI’s role in the EU’s green transition has been recognized, there is still a need for technological and policy solutions to foster its adoption
PROGETTAZIONE, SINTESI, STUDI SAR E VALUTAZIONE BIOLOGICA DI NUOVIINIBITORI DELL’ENZIMA FAAH
No full text
Green infrastructure as a tool of urban regeneration, for an equitable and sustainable planning. An application case at l'Eixample, Barcelona
No full textGreen infrastructure concept, as a possible solution to tackle some territorial challenges, is mainly applied on a territorial scale, while on the urban one it’s still little explored. This study questions the green infrastructure value as a spatial device in urban regeneration processes, proposing a reinterpretation and an operative method of project action. The proposed green infrastructure model incorporates and combines the environmental and sustainable components, with those of urban life organization (activities and services, transport, quality of open and built-up area, ...) and helps to improve their quality and mutual relationships. The description of specific requirements and the definition of indicators by which to measure the context starting conditions and the transformation effects, guide the decision-maker in carrying out the interventions, mainly through the requirements of multi-scalarity, accessibility, environmental sustainability, spaces and services quality and comfort and urban resilience.
The model is applied to the districts of L'Esquerra de l'Eixample in Barcelona, characterized by high population density, pollution problems and lack of greenery.
It acts on three interconnected different scales: urban, through linear interventions that build connections and continuity; neighborhood, with smaller but distributed interventions on block interiors; local, linking the scattered elements in the territory portions through paths.
An integrated system of public spaces, services and green areas is thus outlined, guaranteeing access to urban opportunities by developing a system of connections alternative to motorized traffic able to connect the population with natural and anthropic resources and with the urban settlement new life centers
- …
