Study by optical spectroscopy and molecular dynamics of the interaction of acridine-spermine conjugate with DNA

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A new hybrid: Artesunate-Tumacona B

In recent years, the emergence of Plasmodium strains resistant to artemisinin derivatives, such as the commercial antimalarial Artesunate, has been detected. For this reason, in the search for new strategies to malaria control, we used the antiplasmodial activity of natural products from plant Solanum nudum, such as Tumacona B (SN2), to synthesize a new hybrid Artesunate-Tumacona B. The antiplasmodial activity and cytotoxicity of this hybrid was evaluated in vitro. We found a potent activity with IC50 = 0.0044μM in the strain 3D7 (chloroquine sensitive) and IC50= 0.0059 μM for the strain FCR3 (chloroquine resistant) and low cytotoxicity in HepG2 human liver cells with a CC50 = 12.6 μM. This makes the hybrid a new and promising compound

On the Influence of Stochastic Moments in the Solution of the Neutron Point Kinetics Equation

On the Influence of Stochastic Moments in the Solution of the Neutron Point Kinetics EquationComment: 12 pages, 2 figure

Solving nonlinear problems by Ostrowski Chun type parametric families

In this paper, by using a generalization of Ostrowski' and Chun's methods two bi-parametric families of predictor-corrector iterative schemes, with order of convergence four for solving system of nonlinear equations, are presented. The predictor of the first family is Newton's method, and the predictor of the second one is Steffensen's scheme. One of them is extended to the multidimensional case. Some numerical tests are performed to compare proposed methods with existing ones and to confirm the theoretical results. We check the obtained results by solving the molecular interaction problem.This research was supported by Ministerio de Ciencia y Tecnologia MTM2011-28636-C02-02 and FONDOCYT, Republica Dominicana.Cordero Barbero, A.; Maimo, J.; Torregrosa Sánchez, JR.; Vassileva, M. (2015). Solving nonlinear problems by Ostrowski Chun type parametric families. Journal of Mathematical Chemistry. 53(1):430-449. https://doi.org/10.1007/s10910-014-0432-zS430449531M.S. Petkovic̀, B. Neta, L.D. Petkovic̀, J. Dz̆unic̀, Multipoint Methods for Solving Nonlinear Equations (Academic, New York, 2013)M. Mahalakshmi, G. Hariharan, K. Kannan, The wavelet methods to linear and nonlinear reaction–diffusion model arising in mathematical chemistry. J. Math. Chem. 51(9), 2361–2385 (2013)P.G. Logrado, J.D.M. Vianna, Partitioning technique procedure revisited: Formalism and first application to atomic problems. J. Math. Chem. 22, 107–116 (1997)C.G. Jesudason, I. Numerical nonlinear analysis: differential methods and optimization applied to chemical reaction rate determination. J. Math. Chem. 49, 1384–1415 (2011)K. Maleknejad, M. Alizadeh, An efficient numerical scheme for solving hammerstein integral equation arisen in chemical phenomenon. Procedia Comput. Sci. 3, 361–364 (2011)R.C. Rach, J.S. Duan, A.M. Wazwaz, Solving coupled Lane–Emden boundary value problems in catalytic diffusion reactions by the Adomian decomposition method. J. Math. Chem. 52, 255–267 (2014)J.F. Steffensen, Remarks on iteration. Skand. Aktuar Tidskr. 16, 64–72 (1933)J.M. Ortega, W.C. Rheinboldt, Iterative Solution of Nonlinear Equations in Several Variables (Academic, New York, 1970)H.T. Kung, J.F. Traub, Optimal order of one-point and multipoint iteration. J. ACM 21, 643–651 (1974)J.R. Sharma, R.K. Guha, R. Sharma, An efficient fourth order weighted-Newton method for systems of nonlinear equations. Numer. Algorithms 62, 307–323 (2013)J.R. Sharma, H. Arora, On efficient weighted-Newton methods for solving systems of nonlinear equations. Appl. Math. Comput. 222, 497–506 (2013)M. Abad, A. Cordero, J.R. Torregrosa, Fourth- and fifth-order methods for solving nonlinear systems of equations: an application to the Global positioning system. Abstr. Appl. Anal.(2013) Article ID:586708. doi: 10.1155/2013/586708F. Soleymani, T. Lotfi, P. Bakhtiari, A multi-step class of iterative methods for nonlinear systems. Optim. Lett. 8, 1001–1015 (2014)M.T. Darvishi, N. Darvishi, SOR-Steffensen-Newton method to solve systems of nonlinear equations. Appl. Math. 2(2), 21–27 (2012). doi: 10.5923/j.am.20120202.05F. Awawdeh, On new iterative method for solving systems of nonlinear equations. Numer. Algorithms 5(3), 395–409 (2010)D.K.R. Babajee, A. Cordero, F. Soleymani, J.R. Torregrosa, On a novel fourth-order algorithm for solving systems of nonlinear equations. J. Appl. Math. (2012) Article ID:165452. doi: 10.1155/2012/165452A. Cordero, J.R. Torregrosa, M.P. Vassileva, Pseudocomposition: a technique to design predictor–corrector methods for systems of nonlinear equations. Appl. Math. Comput. 218(23), 1496–1504 (2012)A. Cordero, J.R. Torregrosa, M.P. Vassileva, Increasing the order of convergence of iterative schemes for solving nonlinear systems. J. Comput. Appl. Math. 252, 86–94 (2013)A.M. Ostrowski, Solution of Equations and System of Equations (Academic, New York, 1966)C. Chun, Construction of Newton-like iterative methods for solving nonlinear equations. Numer. Math. 104, 297–315 (2006)R. King, A family of fourth order methods for nonlinear equations. SIAM J. Numer. Anal. 10, 876–879 (1973)A. Cordero, J.R. Torregrosa, Low-complexity root-finding iteration functions with no derivatives of any order of convergence. J. Comput. Appl. Math. (2014). doi: 10.1016/j.cam.2014.01.024A. Cordero, J.L. Hueso, E. Martínez, J.R. Torregrosa, A modified Newton Jarratts composition. Numer. Algorithms 55, 87–99 (2010)P. Jarratt, Some fourth order multipoint methods for solving equations. Math. Comput. 20, 434–437 (1966)A. Cordero, J.R. Torregrosa, Variants of Newtons method using fifth-order quadrature formulas. Appl. Math. Comput. 190, 686–698 (2007)Z. Liu, Q. Zheng, P. Zhao, A variant of Steffensens method of fourth-order convergence and its applications. Appl. Math. Comput. 216, 1978–1983 (2010)A. Cordero, J.R. Torregrosa, A class of Steffensen type methods with optimal order of convergence. Appl. Math. Comput. 217, 7653–7659 (2011)L.B. Rall, New York, Computational Solution of Nonlinear Operator Equations (Robert E. Krieger Publishing Company Inc, New York, 1969

Some viable models for digital public-interest journalism

The supply of public interest journalism that serves the needs of citizens in a democratic society has always been scarce in the media marketplace when compared with sensationalism, gossip, entertainment, propaganda, and misinformation. This scarce commodity, whose market value lies in its credibility and depends on costly investments of time and money in professional research, has frequently required a subsidy, which for more than a century was provided by advertising. Now that this subsidy has mostly been devoured by technological platforms such as Google and Facebook, the industry and profession are developing new models focused on user needs and wants with a trend toward public service rather than profit. This paper uses deductive and critical methodologies to identify the most promising business models used by media companies to counteract the decline in public-interest journalism. Our proposal is that an appropriate business model can be the best way to revitalize media companies. The research is based on Chesbrough’s business model framework applied to 20 leading digital news publications from 16 countries. In addition, we analyze how Covid-19 has impacted those business models

Parnassius apollo nevadensis: identification of recent population structure and source–sink dynamics

Population persistence depends in many cases on gene flow between local populations. Parnassius apollo nevadensis is an endemic subspecies of Apollo butterfly in the Sierra Nevada (southern Spain), whose populations are distributed in discrete patches at altitudes between 1850 and 2700 m. In this paper, we use 13 microsatellite loci to examine the genetic structure of this P. apollo subspecies. We revealed both a strong pattern of isolation by distance (which was stronger when calculated with realistic travel distances that accounted for topography) and source–sink dynamics. The observed population genetic structure is consistent with strongly asymmetrical gene flow, leading to constant directional migration and differential connectivity among the populations. The apparently contradictory results from the clustering algorithms (Structure and Geneland) are also consistent with a recent (<100 ya) reduction in the distribution range. The results point to global warming as a possible cause of this reduction, as in other populations of this species. We identify some natural and anthropogenic barriers to gene flow that may be the cause of the recent population structure and source–sink dynamics

Comparative pan-genome analysis of Piscirickettsia salmonis reveals genomic divergences within genogroups

Indexación: Scopus.Piscirickettsia salmonis is the etiological agent of salmonid rickettsial septicemia, a disease that seriously affects the salmonid industry. Despite efforts to genomically characterize P. salmonis, functional information on the life cycle, pathogenesis mechanisms, diagnosis, treatment, and control of this fish pathogen remain lacking. To address this knowledge gap, the present study conducted an in silico pan-genome analysis of 19 P. salmonis strains from distinct geographic locations and genogroups. Results revealed an expected open pan-genome of 3,463 genes and a core-genome of 1,732 genes. Two marked genogroups were identified, as confirmed by phylogenetic and phylogenomic relationships to the LF-89 and EM-90 reference strains, as well as by assessments of genomic structures. Different structural configurations were found for the six identified copies of the ribosomal operon in the P. salmonis genome, indicating translocation throughout the genetic material. Chromosomal divergences in genomic localization and quantity of genetic cassettes were also found for the Dot/Icm type IVB secretion system. To determine divergences between core-genomes, additional pan-genome descriptions were compiled for the so-termed LF and EM genogroups. Open pan-genomes composed of 2,924 and 2,778 genes and core-genomes composed of 2,170 and 2,228 genes were respectively found for the LF and EM genogroups. The core-genomes were functionally annotated using the Gene Ontology, KEGG, and Virulence Factor databases, revealing the presence of several shared groups of genes related to basic function of intracellular survival and bacterial pathogenesis. Additionally, the specific pan-genomes for the LF and EM genogroups were defined, resulting in the identification of 148 and 273 exclusive proteins, respectively. Notably, specific virulence factors linked to adherence, colonization, invasion factors, and endotoxins were established. The obtained data suggest that these genes could be directly associated with inter-genogroup differences in pathogenesis and host-pathogen interactions, information that could be useful in designing novel strategies for diagnosing and controlling P. salmonis infection. © 2017 Nourdin-Galindo, Sánchez, Molina, Espinoza-Rojas, Oliver, Ruiz, Vargas-Chacoff, Cárcamo, Figueroa, Mancilla, Maracaja-Coutinho and Yañez.https://www.frontiersin.org/articles/10.3389/fcimb.2017.00459/ful

Effect of temperature on product performance of a high ash biomass during fast pyrolysis and its bio-oil storage evaluation

Bio-oil from the fast pyrolysis of agro-residues still needs to contemplate different production scenarios to look for its feasibility. For this reason, in this work the effect of a range of fast pyrolysis temperature (450, 480, 510 and 550 °C) processing rape straw biomass (with high K content) has been studied in a continuous bubbling fluidised bed reactor. It was found that the catalytic effect of the inorganic content was different at each fast pyrolysis temperature, with the lower temperatures resulting in the highest yield of bio-oil due to minor catalytic effect (up to 41.39 wt%). It was also found that at 480 °C the bio-oil presented the best combination of physico-chemical features such as non-separation phase and the lowest water content; yield (39.65 wt%) and HHV (19.23 MJ/kg), containing a high concentration of phenolic compounds. At the fast pyrolysis temperature of 510 °C and 550 °C, the conjunction effect of temperature and the catalytic effect provoked bio-oil separation into two phases and a higher gas yield than was expected. Then, the higher temperatures are not suitable for bio-oil production. Char is also an interesting co-product for all pyrolysis temperatures

Short communication: Effects of the addition of a marigold extract to diets fed to channel catfish (Ictalurus punctatus) on growth parameters

The expansion of aquaculture in the last 10 years has made it an important source of protein worldwide. However, increased production, and the culture intensification it carries, results in higher risk of infectious disease due to poor water quality and high stocking densities. ... Marigold (Tagetes erecta L.) is a plant native to Mexico whose flowers accumulate carotenoids. Natural carotenoids extracted from marigold have been used in aquaculture to help in the survival of fish juvenile stages by strengthening their immunological system, thus reducing mortality rates. The effect of carotenoids in fish health may exert a positive effect on fish growth indices; however, these effects on growth parameters have not been studied in channel catfish (Ictalurus punctatus), which is the most cultured fish species in north-eastern Mexico, and one of the most cultured on the southern United States. Consequently, the aim of this study was to investigate if there were significant differences in growth among channel catfish juveniles when fed diets containing various carotenoid doses from a natural source