992 research outputs found
Lorentz-CPT violation, radiative corrections and finite temperature
In this work we investigate the radiatively induced Chern-Simons-like terms
in four-dimensions at zero and finite temperature. We use the approach of
rationalizing the fermion propagator up to the leading order in the
CPT-violating coupling . In this approach, we have shown that although
the coefficient of Chern-Simons term can be found unambiguously in different
regularization schemes at zero or finite temperature, it remains undetermined.
We observe a correspondence among results obtained at finite and zero
temperature.Comment: To appear in JHEP, 10 pages, 1 eps figure, minor changes and
references adde
Non-Anticoagulant Heparan Sulfate from the Ascidian Phallusia nigra Prevents Colon Carcinoma Metastasis in Mice by Disrupting Platelet-Tumor Cell Interaction
Although metastasis is the primary cause of death in patients with malignant solid tumors, efficient anti-metastatic therapies are not clinically available currently. Sulfated glycosaminoglycans from marine sources have shown promising pharmacological effects, acting on different steps of the metastatic process. Oversulfated dermatan sulfates from ascidians are effective in preventing metastasis by inhibition of P-selectin, a platelet surface protein involved in the platelet-tumor cell emboli formation. We report in this work that the heparan sulfate isolated from the viscera of the ascidian Phallusia nigra drastically attenuates metastases of colon carcinoma cells in mice. Our in vitro and in vivo assessments demonstrate that the P. nigra glycan has very low anticoagulant and antithrombotic activities and a reduced hypotension potential, although it efficiently prevented metastasis. Therefore, it may be a promising candidate for the development of a novel anti-metastatic drug
Effective cytocompatible nanovectors based on serine-derived gemini surfactants and monoolein for small interfering RNA delivery
Supplementary data to this article can be found online athttps://doi.org/10.1016/j.jcis.2020.09.077.Non-viral gene therapy based on gene silencing with small interfering RNA (siRNA) has attracted great interest over recent years. Among various types of cationic complexation agents, amino acid-based surfactants have been recently explored for nucleic acid delivery due to their low toxicity and high biocompatibility. Monoolein (MO), in turn, has been used as helper lipid in liposomal systems due to its ability to form inverted nonbilayer structures that enhance fusogenicity, thus contributing to higher transfection efficiency. In this work, we focused on the development of nanovectors for siRNA delivery based on three gemini amino acid-based surfactants derived from serine (12Ser)2N12, amine derivative; (12Ser)2COO12, ester derivative; and (12Ser)2CON12, amide derivative individually combined with MO as helper lipid. The inclusion of MO in the cationic surfactant system influences the morphology and size of the mixed aggregates. Furthermore, the gemini surfactant:MO systems showed the ability to efficiently complex siRNA, forming stable lipoplexes, in some cases clearly depending on the MO content, without inducing significant levels of cytotoxicity. High levels of gene silencing were achieved in comparison with a commercially available standard indicating that these gemini:MO systems are promising candidates as lipofection vectors for RNA interference (RNAi)-based therapies.The authors acknowledge Fundação para a CiĂȘncia e a Tecnolo-gia (FCT) for financial support through projects UIDB/00081/2020 and UIDB/50006/2020. This work was supported by theââContrato-Programaâ UIDB/04050/2020 funded by national fundsthrough the FCT I.P. Dr. Marisa Passos is gratefully acknowledged for help with the statistical analysis of cytotoxicity data. Fundingby the CCDR-N/NORTE2020/Portugal2020 through project DESign-BIOtechHealth (ref. Norte-01-0145-FEDER-000024) is also acknowledged. I. S. Oliveira and S.G. Silva also acknowledge finan-cial support from FCT through PhD grant SFRH/BD/108629/2015 and Individual Call to Scientific Employment Stimulus - CEEC Indi-vidual grant CEECIND/01932/2017, respectivelyinfo:eu-repo/semantics/publishedVersio
Structure, electronic properties, morphology evolution, and photocatalytic activity in PbMoO4 and Pb12xCaxSrxMoO4 (x = 0.1, 0.2, 0.3, 0.4 and 0.5) solid solutions
In this work PbMoO4 and Pb12xCaxSrxMoO4 (x = 0.1, 0.2, 0.3, 0.4 and 0.5) solid solutions have been
successfully prepared, for the first time, by a simple co-precipitation method and the as-synthesized
samples were subjected to a water-based reflux treatment. Structural characterization of these samples
was performed using X-ray diffraction with Rietveld refinement analysis and Raman spectroscopy. Their
optical properties were investigated by UV-Vis absorption spectroscopy and PL emissions, and the
photocatalytic activity of the as-synthesized samples for the degradation process of Rhodamine B has
been demonstrated. The surface structure and morphologies were characterized by field emission
scanning electron microscopy. To complement and rationalize the experimental results, the geometry,
electronic structures, and morphologies of as-synthesized samples were characterized by first-principles
quantum-mechanical calculations at the density functional theory level. By using Wulff construction,
based on the values of the surface energies for the (001), (100), (110), (111), (011) and (112) surfaces, a
complete map of the available morphologies for PbMoO4 was obtained and a good agreement between
the experimental and theoretical predicted morphologies was found. The structural and electronic
changes induced by the substitution of Pb by Ca and Sr allow us to find a relationship among
morphology, the electron-transfer process at the exposed surfaces, optical properties, and
photocatalytic activity. We believe that our results offer new insights regarding the local coordination of
superficial Pb/Ca/Sr and Mo cations (i.e., clusters) on each exposed surface of the corresponding
morphology, which dictate the photocatalytic activities of the as-synthesized samples, a field that has
so far remained unexplored. The present study, which combines multiple experimental methods and
first-principles calculations, provides a deep understanding of the local structures, bonding,
morphologies, band gaps, and electronic and optical properties, and opens the door to exploit the
electrical, optical and photocatalytic activity of this very promising family of materials
Women's refolution at work
The renowned Age of Revolution encompasses the period between the American
Revolution (1776) and the so-called Spring of Nations in 1848, this being the height
of the revolutionary movements in Europe in the 19th century, though it may be
considered just the tip of the iceberg as far as civil rights movements for people from
all walks of life are concerned. The changes that occurred throughout this timespan
intended to move from feudal and absolutist systems, considered old-fashioned and
ill-suited, to constitutionalist states and republics that would be able to heed the
new values, e.g. liberalism, nationalism and socialism, as well as the demands of the
working classes, enduring the harmful effects of industrialisation. Working people
had been flowing into large industrial cities for over a century since the onset of the
Industrial Revolution, leaving behind their home places and settling in overcrowded,
rundown dwellings in appalling living conditions. The shift from working at home to
working in factories brought along a number of issues that would be the motivation
for setting up trade unions, namely the long working hours (between 12 and 14 hours
per day), the low wages, the cruel discipline and the fierce system of fines that was
applied, and the numerous accidents and health issues that ensued. Despite the overall
negative conditions, women and children were among those who suffered the
most, especially because the formerâs wages were regarded as secondary earnings
and thus less important than menâs. Consequently, from 1850s onwards, trade unions
began to fight for better paid workers and women were initially excluded from these
structures be it as members or leaders, being supported by social reformers instead.
As a case in point, it is worth mentioning Clementina Black who, in 1888, set forth a
demand for equal pay between men and women in the UK and the Bryant and May
match factory strike which was held in the same year. Bearing in mind this social and
historical context, our aim with this paper is two-fold: not only do we seek to focus
on unionist movements in the last half of the 19th century in the European context
as a means to fight against conservative and slavery-like practices in the workplace
but we also wish to emphasise the place and importance of working-class women in
this general workersâ assertion, particularly in their attempt to gain equal pay, a true
refolution that would be the motivational beacon for 20th century movements, such
as that of the suffragettes.info:eu-repo/semantics/publishedVersio
Characterization of growth and metabolism of the haloalkaliphile Natronomonas pharaonis
Natronomonas pharaonis is an archaeon adapted to two extreme conditions: high salt concentration and alkaline pH. It has become one of the model organisms for the study of extremophilic life. Here, we present a genome-scale, manually curated metabolic reconstruction for the microorganism. The reconstruction itself represents a knowledge base of the haloalkaliphile's metabolism and, as such, would greatly assist further investigations on archaeal pathways. In addition, we experimentally determined several parameters relevant to growth, including a characterization of the biomass composition and a quantification of carbon and oxygen consumption. Using the metabolic reconstruction and the experimental data, we formulated a constraints-based model which we used to analyze the behavior of the archaeon when grown on a single carbon source. Results of the analysis include the finding that Natronomonas pharaonis, when grown aerobically on acetate, uses a carbon to oxygen consumption ratio that is theoretically near-optimal with respect to growth and energy production. This supports the hypothesis that, under simple conditions, the microorganism optimizes its metabolism with respect to the two objectives. We also found that the archaeon has a very low carbon efficiency of only about 35%. This inefficiency is probably due to a very low P/O ratio as well as to the other difficulties posed by its extreme environment
Laboratory Microprobe X-Ray Fluorescence in Plant Science: Emerging Applications and Case Studies
In vivo and micro chemical analytical methods have the potential to improve our understanding of plant metabolism and development. Benchtop microprobe X-ray fluorescence spectroscopy (Ό-XRF) presents a huge potential for facing this challenge. Excitation beams of 30 Όm and 1 mm in diameter were employed to address questions in seed technology, phytopathology, plant physiology, and bioremediation. Different elements were analyzed in several situations of agronomic interest: (i) Examples of Ό-XRF yielding quantitative maps that reveal the spatial distribution of zinc in common beans (Phaseolus vulgaris) primed seeds. (ii) Chemical images daily recorded at a soybean leaf (Glycine max) infected by anthracnose showed that phosphorus, sulfur, and calcium trended to concentrate in the disease spot. (iii) In vivo measurements at the stem of P. vulgaris showed that under root exposure, manganese is absorbed and transported nearly 10-fold faster than iron. (iv) Quantitative maps showed that the lead distribution in a leaf of Eucalyptus hybrid was not homogenous, this element accumulated mainly in the leaf border and midrib, the lead hotspots reached up to 13,400 mg lead kg-1 fresh tissue weight. These case studies highlight the ability of Ό-XRF in performing qualitative and quantitative elemental analysis of fresh and living plant tissues. Thus, it can probe dynamic biological phenomena non-destructively and in real time
Venom alkaloids against Chagas disease parasite: search for effective therapies
Chagas disease is an important disease affecting millions of patients in the New World and is caused by a protozoan transmitted by haematophagous kissing bugs. It can be treated with drugs during the early acute phase; however, effective therapy against the chronic form of Chagas disease has yet to be discovered and developed. We herein tested the activity of solenopsin alkaloids extracted from two species of fire ants against the protozoan parasite Trypanosoma cruzi, the aetiologic agent of Chagas disease. Although IC50 determinations showed that solenopsins are more toxic to the parasite than benznidazole, the drug of choice for Chagas disease treatment, the ant alkaloids presented a lower selectivity index. As a result of exposure to the alkaloids, the parasites became swollen and rounded in shape, with hypertrophied contractile vacuoles and intense cytoplasmic vacuolization, possibly resulting in osmotic stress; no accumulation of multiple kinetoplasts and/or nuclei was detected. Overexpressing phosphatidylinositol 3-kinaseâan enzyme essential for osmoregulation that is a known target of solenopsins in mammalian cellsâdid not prevent swelling and vacuolization, nor did it counteract the toxic effects of alkaloids on the parasites. Additional experimental results suggested that solenopsins induced a type of autophagic and programmed cell death in T. cruzi. Solenopsins also reduced the intracellular proliferation of T. cruzi amastigotes in infected macrophages in a concentration-dependent manner and demonstrated activity against Trypanosoma brucei rhodesiense bloodstream forms, which is another important aetiological kinetoplastid parasite. The results suggest the potential of solenopsins as novel natural drugs against neglected parasitic diseases caused by kinetoplastids.Fil: Silva, Rafael C. M. Costa. Universidade Federal do Rio de Janeiro; BrasilFil: Fox, Eduardo G. P.. Universidade Federal do Rio de Janeiro; Brasil. South China Agricultural University; ChinaFil: Gomes, Fabio M.. Universidade Federal do Rio de Janeiro; Brasil. National Institutes of Health; Estados UnidosFil: FeijĂł, Daniel F.. Universidade Federal do Rio de Janeiro; BrasilFil: Ramos, Isabela. Universidade Federal do Rio de Janeiro; BrasilFil: Koeller, Carolina M.. Universidade Federal do Rio de Janeiro; Brasil. University at Buffalo; Estados UnidosFil: Costa, Tatiana F. R.. Universidade Federal do Rio de Janeiro; BrasilFil: Rodrigues, Nathalia S.. Universidade Federal do Rio de Janeiro; BrasilFil: Lima, Ana P.. Universidade Federal do Rio de Janeiro; BrasilFil: Atella, Georgia C.. Universidade Federal do Rio de Janeiro; BrasilFil: Rocha de Miranda, Kildare. Universidade Federal do Rio de Janeiro; Brasil. Instituto Nacional de CiĂȘncia e Tecnologia em Biologia Estrutural e Bioimagem; BrasilFil: Schoijet, Alejandra Cecilia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Alonso, Guillermo Daniel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: de AlcĂąntara Machado, Ednildo. Universidade Federal do Rio de Janeiro; BrasilFil: Heise, Norton. Universidade Federal do Rio de Janeiro; Brasi
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