Synthesis, thermal behavior, and aggregation in aqueous solution of poly(methyl methacrylate)-b-poly(2-hydroxyethyl methacrylate)

Indexación: ScieloABSTRACT Amphiphilic block copolymers of poly(methyl methacrylate) PMMA and poly(2-hidroxyethyl methacrylate) PHEMA were synthesized by a two-step atom transfer radical polymerization (ATRP). Copolymers with various degrees of polymerization and different relative block sizes were obtained. The structure of the resulting polymers have been characterized and verified by FT-IR and 1H-NMR, molecular weight were determined by size exclusion chromatography analyses. The thermal properties of these polymers were investigated by differential scanning calorimetry DSC and thermogravimetric analysis TGA. The glass transition temperature of mono halogenated PMMA increases from 116 °C to 123 °C with increasing molecular weight, whereas the glass transition temperature of block copolymers depends slightly on polymer structure. The derivatives of TGA curves indicate that thermal degradation occurs in one stage. The self-assembly of PMMA-b-PHEMA in aqueous solution have been investigated by fluorescence probing methods. The critical micelle concentrations are in the range 10-6 - 10-7 M. The micropolarity sensed by pyrene is higher than in aggregates formed by block copolymers based on polystyrene. Keywords: Block copolymers, glass transition temperature, thermogravimetric analysis, critical micelle concentration, fluorescence probing methods

Gateway Modeling and Simulation Plan

This plan institutes direction across the Gateway Program and the Element Projects to ensure that Cross Program M&S are produced in a manner that (1) generate the artifacts required for NASA-STD-7009 compliance, (2) ensures interoperability of M&S exchanged and integrated across the program and, (3) drives integrated development efforts to provide cross-domain integrated simulation of the Gateway elements, space environment, and operational scenarios. This direction is flowed down via contractual enforcement to prime contractors and includes both the GMS requirements specified in this plan and the NASASTD- 7009 derived requirements necessary for compliance. Grounding principles for management of Gateway Models and Simulations (M&S) are derived from the Columbia Accident Investigation Board (CAIB) report and the Diaz team report, A Renewed Commitment to Excellence. As an outcome of these reports, and in response to Action 4 of the Diaz team report, the NASA Standard for Models and Simulations, NASA-STD-7009 was developed. The standard establishes M&S requirements for development and use activities to ensure proper capture and communication of M&S pedigree and credibility information to Gateway program decision makers. Through the course of the Gateway program life cycle M&S will be heavily relied upon to conduct analysis, test products, support operations activities, enable informed decision making and ultimately to certify the Gateway with an acceptable level of risk to crew and mission. To reduce risk associated with M&S influenced decisions, this plan applies the NASA-STD-7009 requirements to produce the artifacts that support credibility assessments and ensure the information is communicated to program management

Mean Dimension and Metric Mean Dimension for Non-autonomous Dynamical Systems

In this paper we extend the definitions of mean dimension and metric mean dimension for non-autonomous dynamical systems. We show some properties of this extension and furthermore some applications to the mean dimension and metric mean dimension of single continuous maps

Adjuvants : an essential component of neisseria vaccines

Adjuvants may be classified into delivery systems and immune potentiator or modulator molecules based on their mechanism of action. Neisseria vaccines containing traditional adjuvants such as aluminium salts have existed for long time, but meningitis caused by Neisseria meningitidis serogroups, particularly serogroup B, continues to be a global health problem. Novel strategies have applied in silico and recombinant technologies to develop "universal" antigens (e.g. proteins, peptides and plasmid DNA) for vaccines, but these antigens have been shown to be poorly immunogenic even when alum adjuvanted, implying a need for better vaccine design. In this work we review the use of natural, detoxified, or synthetic molecules in combination with antigens to activate the innate immune system and to modulate the adaptive immune responses. In the main, antigenic and imune potentiator signals are delivered using nano-, micro-particles, alum, or emulsions. The importance of interaction between adjuvants and antigens to activate and target dendritic cells, the bridge between the innate and adaptive immune systems, will be discussed. In addition, nasal vaccine strategies based on the development of mucosal adjuvants and Neisseria derivatives to eliminate the pathogen at the site of infection provide promising adjuvants effective not only against respiratory pathogens, but also against pathogens responsible for enteric and sexually transmitted diseases

Cochleates derived from Vibrio cholerae O1 proteoliposomes : The impact of structure transformation on mucosal immunisation

Cochleates are phospholipid-calcium precipitates derived from the interaction of anionic lipid vesicles with divalent cations. Proteoliposomes from bacteria may also be used as a source of negatively charged components, to induce calcium-cochleate formation. In this study, proteoliposomes from V. cholerae O1 (PLc) (sized 160.7±1.6 nm) were transformed into larger (16.3±4.6 µm) cochleate-like structures (named Adjuvant Finlay Cochleate 2, AFCo2) and evaluated by electron microscopy (EM). Measurements from transmission EM (TEM) showed the structures had a similar size to that previously reported using light microscopy, while observations from scanning electron microscopy (SEM) indicated that the structures were multilayered and of cochleate-like formation. The edges of the AFCo2 structures appeared to have spaces that allowed penetration of negative stain or Ovalbumin labeled with Texas Red (OVA-TR) observed by epi-fluorescence microscopy. In addition, freeze fracture electron microscopy confirmed that the AFCo2 structures consisted of multiple overlapping layers, which corresponds to previous descriptions of cochleates. TEM also showed that small vesicles co-existed with the larger cochleate structures, and in vitro treatment with a calcium chelator caused the AFCo2 to unfold and reassemble into small proteoliposome-like structures. Using OVA as a model antigen, we demonstrated the potential loading capacity of a heterologous antigen and in vivo studies showed that with simple admixing and administration via intragastric and intranasal routes AFCo2 provided enhanced adjuvant properties compared with PLc

Effect of the Target Size in the Calculation of the Energy Deposited Using PENELOPE Code

The specific and linear energy was calculated in target sizes of 10 μm, 5 μm, 1 μm, 60 nm, 40nm and 20 nm by taking into account the contribution of the primary photon beams and the electrons generated by them in LiF: Mg, Ti (TLD-100). The simulations were carried out by the code PENELOPE 2011. Using different histories of primary particles, for each energy beams the mean deposited energy is the same, but to achieve a statistical deviation lower than 1% the value of 108was fixed. We find that setting the values C1 = 0.1 C2 = 0.1 and Wcc = Wcr = 50 eV the time of simulation decreases around the 25%. The uncertainties (1 SD) in the specific energy increases with energy for all target sizes and decreases with target size, with values from 1.7 to 94% for 20 nm and between 0.1 and 0.8% for 10 μm. As expected, the specific and linear energies decrease with target size but not in a geometrical behavior

Association between agility and speed with changes of direction in young players

Identificar factores asociados al máximo rendimiento en el fútbol posibilitará mejorar el proceso de planificación deportiva en etapas tempranas. Este estudio tuvo como objetivo determinar la asociación entre la agilidad y la velocidad con cambios de dirección (VCD) en jóvenes futbolistas (JF). Participaron voluntariamente dieciocho hombres entre los 10 y 13 años los cuales aplicaron el test de 20 metros con cambios de dirección (T20CD) y el test de agilidad Illinois (TAI). El análisis estadístico se realizó en el IBM SPSS V.22 en el cual se fijó para la significancia un p0,05) y no normal en TAI (p<0,05), el coeficiente correlacional de Spearman (r = 0,06; p = 0,8) evidenció una relación poco significativa (p<0,05). Por lo tanto se concluye que no existe asociación significativa entre la agilidad y la VCD en JF

Rethinking education for sustainability in management education : going beyond metrics toward human virtues

Education for sustainable development (ESD) initially emerged around the 1990s, and it has opened the possibility to re-think areas such as management education. Although the original purpose of inclusiveness and creativity has been gradually replaced by metrics, while keeping the idea of “development as growth” largely unquestioned, drawing upon the work of organisational researchers like Heather Hopfl, this chapter presents a critique of the evolution of ESD in the UK revealing a rationale that transforms guiding principles into metrics, emphasising “efficiency” over “care.” The researchers relate to the principles of humanistic management, in its consideration of social value generation linked to financial success. The authors propose to enhance the notion of “values” by revisiting the concept of “virtues,” particularly in the consideration of sustainability. Finally, the authors draw upon interest in aesthetics and praxis to propose an “aesthetic education for sustainability,” as a critical and purposeful approach of questioning and imagining hopeful ways of living and learning

Detecção do vírus da bronquite infecciosa das galinhas e do metapneumovírus aviário utilizando uma reação de transcrição reversa com reação em cadeia pela polimerase duplex

A duplex RT-PCR assay is reported for the simultaneous detection of avian infectious bronchitis virus (IBV) and avian metapneumovirus (aMPV), the causative agents of major diseases in poultry. The duplex RT-PCR assay optimized showed a detection limit of 10-3 (101 EID50/50m L for IBV and 100.5 EID50/50m L for aMPV, respectively when two viruses were mixed and 10-1 for each one separated (103 EID50/50m L for IBV and 102.5 EID50/50m L for aMPV, respectively. It was specific, sensitive and applicable for the rapid detection of these viruses in clinical samples.  Descreve-se um ensaio de duplex RT-PCR assay para a detecção simultânea do vírus da bronquite infecciosa das galinhas (IBV) e do metapneumovirus aviário (aMPV), agentes etiológicos de doenças de elevada importância em avicultura. A duplex RT-PCR otimizada mostrou um limiar de detecção de 10-3 (101 EID50/50m L para IBV e 100.5 EID50/50m L para aMPV, respectivamente, quando da combinação dos dois vírus e 10-1 para cada um dos vírus em separado(103 EID50/50m L para IBV e 102.5 EID50/50m L para aMPV, respectivamente. O ensaio foi demonstrado como específico, sensível e aplicável à rápida detecção destes vírus em amostras clínicas.