84 research outputs found
Unusual Behavior of Donor-Acceptor Stenhouse Adducts in Confined Space of a Water-Soluble Pd-8(II) Molecular Vessel
No full textDonor-acceptor Stenhouse adducts (DASA) are new-generation photochromic compounds discovered recently. DASA exist normally in open form (blue/violet) and readily convert to cyclic (light yellow/colorless) zwitterionic form reversibly in the presence of green light in toluene/dioxane. In aqueous medium, the open form is not stable and converts to the cyclic zwitterionic form irreversibly. We report here a new self assembled Pd8 molecular vessel (MV) that can stabilize and store the open form of DASA even in aqueous medium. Reaction of the 90 acceptor cis-(tmeda)Pd(NO3)(2) (M) tmeda = N,N,N',N'tetramethylethane-1,2-diamine] with a symmetric tetraimidazole donor (L, 3,3',5,5'-tetra(1H-imidazol-1-y1)-1,1'-biphenyl) in a 2:1 molar ratio yielded a water-soluble 8+4] self-assembled M8L4 molecular barrel (MV). This barrel (MV) is found to be a potential molecular vessel to store and stabilize the open forms of DASA in aqueous medium over the more stable zwitterionic cyclic form, while in the absence of the barrel the same DASA exist in cyclic zwitterionic form in aqueous medium. The hydrophobic interaction between the cavity and the open form of DASA molecules benefits reaching an out-of-equilibrium or reverse equilibrium state in aqueous medium. The presence of excess MV could even drive the conversion of the stable cyclic form to the open form in aqueous medium. The host guest complex is stable upon irradiating with green light. To the best of our knowledge, this is the first successful attempt to stabilize the open form of DASA molecules in aqueous medium and the first report on the fate of DASA in a confined space discrete molecular architecture. Furthermore, the molecular vessel has been utilized for catalytic Michael addition reactions of a series of nitrostyrene derivatives with 1,3-indandione in aqueous medium
Design and Implementation of an Authentication and Authorization Framework for a Nomadic Service Delivery System
No full textInternet has changed our lives. It has made the true distributed computing paradigm a reality. It has opened up a lot of opportunities both in the research domain and in business domain. One can now think of developing software and make it available to the large community of users. Hyper Text Transfer Protocol (HTTP), which was originally developed for the purpose of requesting/transferring content (text, images, etc.), is now a standard for remotely invoking services and getting back results.
The wireless technologies have also matured. 802.11 is the existing standard for wireless communication in a LAN environment. Today, even the small computers like the Personal Digital Assistants (PDA) is wireless enabled. This makes access to information and computing significantly much more convenient.
Hotspot! server has been designed to provide connectivity and services in public places (called hotspots). It acts as a wireless Network Access Server (NAS) to users who want to obtain connectivity and services at public places. We believe that the primary applications that have importance and relevance in public places are Internet Access, and specific context-based or location specific services. These services are deployed by Internet Service Providers. Secure access is one of the primary concerns in public networks. We designed, developed and tested a framework for secure access to HTTP-based services through the Hotspot! server. Internet Access is a special case of a HTTP-based Proxy service
The unusual case of child tantrum - a case report
No full textThis is an amazing case report about an eight years old child that displayed child tantrum more synonym of the younger age group. This case also entails how the author managed to uncover the true reasons for his tantrum that left his guardian truly amazed at the ability of physicians to solve a seemingly difficult behavioural problem
Randomized controlled trial about pain medication flupirtine ignores recent pharmacovigilance warnings
No full textLivia Puljak1,2 1Laboratory for Pain Research, University of Split School of Medicine, Split, Croatia; 2Department for Development, Research and Health Technology Assessment, Agency for Quality and Accreditation in Health Care and Social Welfare, Zagreb, CroatiaOn October 16, 2017 in the Journal of Pain Research, a randomized controlled trial (RCT) comparing efficacy and safety of flupirtine versus piroxicam in postoperative pain in patients undergoing lower limb surgery was published.1 However, this paper fails to report important information. Author’s reply Sowmya Chinnaiyan,1 Narayana Sarala,1 Heddur Shanthappa Arun21Department of Pharmacology, 2Department of Orthopedics, Sri Devaraj Urs Medical College, Sri Devaraj Urs Academy of Higher Education and Research, Kolar, Karnataka, India We thank Livia Puljak for the valuable insights on the article titled “A comparative study of efficacy and safety of flupirtine versus piroxicam in postoperative pain in patients undergoing lower limb surgery” published in the Journal of Pain Research. The concerns highlighted in the Letter to the Editor have been answered.View the original paper by Chinnaiyan and colleagues. 
SEAMERS: A Semi-partitioned Energy-Aware scheduler for heterogeneous MulticorE Real-time Systems
No full textOver the years, the nature of processing platforms is witnessing a significant shift in most of the battery supported real-time systems, which now support a combination of specialized multicores to meet the demands of modern applications. Devising energy-efficient schedulers has become a critical issue for such kinds of devices. Hence, this research presents a low-overhead heuristic strategy named SEAMERS, for DVFS based energy-aware scheduling for a set of real-time periodic tasks on a heterogeneous multicore platform. The presented strategy operates in four phases, namely Deadline Partitioning, Core Clustering, Task Allocation and Energy-Aware Scheduling. Our experimental analysis shows that the presented strategy improves upon the state-of-the-art in terms of energy savings (16% to 47% on average) and enables significant improvement in resource utilization
<span style="font-size:16.0pt;line-height:115%; font-family:"Times New Roman","serif";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">Antidiarrhoeal effects of methanolic root extract of <i>Hemidesmus indicus </i>(Indian sarsaparilla) - An <i>in vitro </i>and <i>in vivo </i>study</span>
No full text363-366Methanolic extract of H. indicus
root (MHI) was screened for its antimicrobial activity against S. typhimurium,
E. coli and S. flexneri, in vitro and in experimentally induced
diarrhoea in albino rats, in vivo. MHI had an anti enterobacteriae effect
as evident from agar well diffusion method and decrease in CFU/ml in MHI
treated LB broth culture. MHI inhibited the castor oil induced diarrhoea in
rats as judged by a decrease in the amount of wet faeces in MHI-pretreated rats
at a dose of 500-1500 mg/kg. The results indicated that MHI was more active
than standard antidiarrhoeal drug, lomotil, Phytochemical tests revealed the
main constituents as tannins, steroids, triterpenoids and carbohydrates.
Present findings suggested that MHI might elicit an antidiarrhoeal effect by
inhibition of intestinal motility and by its bacteriocidal activity
THREE TANK MODEL: A Top down or bottom up dominance analysis
No full text<p>(An old paper published in the Journal of Theoretics)</p>
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<p>The author proposes a simple mechanical model of biomass flow in an ecosystem using a hydrological model. Three tanks representing three trophic levels to determine which form of control is predominantly effective and under what conditions. The model shows that in the question of which is the dominant control, the cascade processes of control from top (predator control) or from bottom (Prey control), Top down control is predominant when the system is predator efficient, where mortality due to intraspecific competition is steady and bottom up control is predominant in systems where the predators are inefficient and mortality due to intraspecific competition is varying dependent on resource levels. The behavior of trophic levels under each type of control is also discussed.</p
Convergência ou divergência das políticas de aprendizagem e educação de adultos?
No full textIn this paper we draw on the theoretical perspective of new institutionalism, particularly on that of world culture and world polity, and discuss the influence of policies of three selected international intergovernmental organisations (IIOs) concerning the recognition of prior learning (RPL) on adult learning and education (ALE) policies, of which RPL is a part, in one developing country from the global South (India) and one developed country from the global North (Germany). Based on a comparative analysis of two country cases, we show that there is evidence of a worldwide convergence of ALE policies as IIOs play a crucial role in the formation and dissemination of European and/or global RPL policies that are based on similar standards. However, it is also evident that this does not indicate a wholesale implementation and adoption of policies, especially in local environments.Neste artigo, inspiramo-nos na perspetiva teórica do novo institucionalismo, particularmente na da cultura mundial e da constituição política mundial, discutindo a influência das políticas de três organizações internacionais governamentais (OI) escolhidas relativamente ao reconhecimento de aprendizagens experienciais (RAE) nas políticas de aprendizagem e educação de adultos (AEA), das quais o RAE faz parte, num país em desenvolvimento do hemisfério sul (Índia) e num país desenvolvido do hemisfério norte (Alemanha). Com base na análise comparativa dos casos de dois países, mostramos que existem provas de uma convergência mundial das políticas de AEA enquanto as OI têm um papel fundamental na formação e divulgação de políticas de RAE europeias e/ou globais que se baseiam-se em standards semelhantes. No entanto, também é evidente que isto não indica uma implementação e adoção generalizada de políticas, principalmente em contextos locais
Extensão de sítios electroquimicamente ativos em PCOSs e EOSs
No full textDoutoramento em Nanociências e NanotecnologiaSolid oxide fuel (SOFCs) and electrolyzer (SOECs) cells have been
promoted as promising technologies for the stabilization of fuel supply
and usage in future green energy systems. SOFCs are devices that
produce electricity by the oxidation of hydrogen or hydrocarbon fuels
with high efficiency. Conversely, SOECs can offer the reverse reaction,
where synthetic fuels can be generated by the input of renewable
electricity. Due to this similar but inverse nature of SOFCs and SOECs,
these devices have traditionally been constructed from comparable
materials.
Nonetheless, several limitations have hindered the entry of SOFCs and
SOECs into the marketplace. One of the most debilitating is associated
with chemical interreactions between cell components that can lead to
poor longevities at high working temperatures and/or depleted
electrochemcial performance. Normally such interreactions are
countered by the introduction of thin, purely ionic conducting, buffer
layers between the electrode and electrolyte interface. The objective of
this thesis is to assess if possible improvements in electrode kinetics can
also be obtained by modifying the transport properties of these buffer
layers by the introduction of multivalent cations.
The introduction of minor electronic conductivity in the surface of the
electrolyte material has previously been shown to radically enhance the
electrochemically active area for oxygen exchange, reducing polarization
resistance losses. Hence, the current thesis aims to extend this
knowledge to tailor a bi-functional buffer layer that can prevent chemical
interreaction while also enhancing electrode kinetics.The thesis selects a typical scenario of an yttria stabilized zirconia
electrolyte combined with a lanthanide containing oxygen electrode.
Gadolinium, terbium and praseodymium doped cerium oxide materials
have been investigated as potential buffer layers. The mixed ionic
electronic conducting (MIEC) properties of the doped-cerium materials
have been analyzed and collated. A detailed analysis is further presented
of the impact of the buffer layers on the kinetics of the oxygen electrode
in SOFC and SOEC devices. Special focus is made to assess for
potential links between the transport properties of the buffer layer and
subsequent electrode performance. The work also evaluates the
electrochemical performance of different K2NiF4 structure cathodes
deposited onto a peak performing Pr doped-cerium buffer layer, the
influence of buffer layer thickness and the Pr content of the ceria buffer
layer. It is shown that dramatic increases in electrode performance can
be obtained by the introduction of MIEC buffer layers, where the best
performances are shown to be offered by buffer layers of highest
ambipolar conductivity. These buffer layers are also shown to continue
to offer the bifunctional role to protect from unwanted chemical
interactions at the electrode/electrolyte interface.As pilhas de combustível e eletrolisadores de óxido sólido (PCOSs e
EOSs) têm sido promovidas a tecnologias promissoras para estabelecer o
abastecimento de combustível e sua utilização futura em sistemas de
energia limpa. As PCOSs são dispositivos que produzem energia elétrica
pela oxidação de combustíveis como o hidrogénio ou de hidrocarbonetos
de elevada eficiência. Alternativamente, as EOSs funcionam de maneira
inversa, na qual podem ser gerados combustíveis sintéticos ao fornecer
energia eléctrica renovável ao sistema. É, pois, devido a esta natureza
semelhante e ainda que inversa, que estes dispositivos têm sido
tradicionalmente construídos a partir de materiais compatíveis.
No entanto, a entrada no mercado destas tecnologias encontra-se ainda
condicionada por diversos factores. Um dos mais limitantes, está
associado a problemas de estabilidade química entre os constituintes da
célula, que podem reduzir a longevidade a elevadas temperaturas de
operação e/ou a um desempenho eletroquímico insuficiente.
Normalmente, tais problemas de compatibilidade são minimizados pela
introdução de uma camada de proteção muito fina constituída por um
material condutor puramente iónico, na interface elétrodo/eletrólito.
Deste modo, o objetivo deste trabalho é avaliar se modificando as
propriedades de transporte destas camadas de proteção se pode conduzir
ao aumento das propriedades de cinética do elétrodo, através da
introdução de catiões polivalentes.
A introdução de condutividade eletrónica menor na superfície do
electrólito foi anteriormente relatada apresentando uma melhoria muito
considerável das zonas eletroquimicamente activas para a permuta de
oxigénio, reduzindo, desta forma, as perdas de resistência de polarização. Assim, esta dissertação tem por objetivo desenvolver este conhecimento
para adaptar uma camada de proteção bifuncional que consiga evitar os
problemas de interação química e ao mesmo tempo aumentar a cinética
dos elétrodos.
Esta dissertação apresenta um cenário típico de um eletrólito à base de
zircónia estabilizada com ítrio combinado com um elétrodo de oxigénio
contendo lantanídeos. Foram investigados como materiais de proteção,
os sistemas de céria dopada com gadolínio, térbio e praseodímio. As
propriedades inerentes à condução eletrónica e iónica mista (MIEC) dos
materiais dopados foram analisadas e agrupadas. Posteriormente, foi
realizada uma análise detalhada sobre o impacto das camadas de
proteção na cinética do elétrodo de oxigénio em dispositivos PCOS e
EOS. Foi dada especial atenção às potenciais relações entre as
propriedades de transporte da camada proteção e subsequente
desempenho do elétrodo. O trabalho também avalia o desempenho
eletroquímico de cátodos de K2NiF4 com diferentes estruturas,
depositadas sobre a camada de proteção que apresentou melhor
desempenho, isto é, a céria dopada com praseodímio, assim como a
influência da espessura da camada e da fração de Pr presente na céria.
Demonstrou-se que a introdução de camadas de proteção à base de
MIECs levou a um aumento drástico no desempenho do elétrodo,
nomeadamente pelos MIECs de maior condutividade ambipolar. Estas
camadas de proteção utlizadas provaram ser também eficazes em manter
o papel de inibidores de interactividade química na interface
elétrodo/eletrólito
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