Which mechanism underlies the water-like anomalies in core-softened potentials?

Using molecular dynamics simulations we investigate the thermodynamic of particles interacting with a continuous and a discrete versions of a core-softened (CS) intermolecular potential composed by a repulsive shoulder. Dynamic and structural properties are also analyzed by the simulations. We show that in the continuous version of the CS potential the density at constant pressure has a maximum for a certain temperature. Similarly the diffusion constant, $D$, at a constant temperature has a maximum at a density $\rho_{\mathrm{max}}$ and a minimum at a density $\rho_{\mathrm{min}}<\rho_{\mathrm{max}}$, and structural properties are also anomalous. For the discrete CS potential none of these anomalies are observed. The absence of anomalies in the discrete case and its presence in the continuous CS potential are discussed in the framework of the excess entropy.Comment: 8 page

Non-adiabatic collapse of a quasi-spherical radiating star

A model is proposed of a collapsing quasi-spherical radiating star with matter content as shear-free isotropic fluid undergoing radial heat-flow with outgoing radiation. To describe the radiation of the system, we have considered both plane symmetric and spherical Vaidya solutions. Physical conditions and thermodynamical relations are studied using local conservation of momentum and surface red-shift. We have found that for existence of radiation on the boundary, pressure on the boundary is not necessary.Comment: 8 Latex pages, No figures, Revtex styl

Assessing the effect of pharmaceutical excipients on the DNA extraction from plant food supplements

in the EU market as ingredients in formulations, which are sold as plant food supplements (PFS). Among the several issues that may affect the safety of PFS, the most relevant concerns aduÍterations by the illegal addition of pharmaceutical drugs and/or the swap/ misidentification ofplant material, with cases of acate toxicity already reported [l]. Owing to the high similarity and distinct therapeutic uses ofseveral medicinal plants, accurate and fast methodologies allowing their distincüon are required. For that purpose, DNA-based methods are considered fast, sensitive and highly specific tools, allowing the unequivocal identification of plant species. Up to date, most of DNA methodologies reporting the identification of plant species essentially concern medicinal plants [2], with few works being developed for the authentication of PFS.This work was supported by the projects EXPL/DTP-SAP/1438/2013 (4SaferPFS) and Pest-C/EQB/LA0006/2013 financed by FCT (Fundação para a Ciência e Tecnologia) (FEDER funds through COMPETE). Teimo J.R. Fernandes is grateful to FCT PhD grant (SFRH/BD/93711/2013) financed by POPH-QREN (subsidised by FSE and MCTES).info:eu-repo/semantics/publishedVersio

Soybean DNA extraction from blended refined vegetable oils

The major genetically modified (GM) crop species is soybean (Glycine max), accounting for 53% of the total world’s GM planted area and 70% of the soybean annual production in 2008 [1]. Since the approval of Roundup Ready® (RR) soybean in EU, the production of soybean oil using GM seeds has been increasing. In EU, the doubts raised by the use of genetically modified organisms (GMO) lead to the mandatory labelling for food products containing more than 0.9% of authorised GMO. In blended edible oils prepared with mixtures of two or more different oils, it is important to verify the labelling statements concerning their constituents and the presence of GM material, since soybean oil is frequently used. The analysis of DNA coupled with polymerase chain reaction (PCR) has been the technique of choice to monitor the presence of GMO in food. However, it is very difficult to obtain amplifiable DNA from oil since most vegetable oils, like crude soybean oil, must be refined prior to its consumption

A survey on genetically modified maize in foods commercialised in Portugal

Maize, the second most important genetically modified (GM) crop, has the highest number of authorised GM events for food and feed in the EU. To provide consumer’s information, labelling for food products containing more than 0.9% of GM material is demanded by the actual EU legislation. Analysis of foods is then essential to detect and quantify GM maize material and verify the compliance with labelling information. The aim of the present work was to assess the presence of GM maize in a range of processed foods commercialised in Portugal between 2007 and 2010. For this purpose, screening of GM material was carried out by qualitative PCR targeting the 35S promoter and the NOS terminator, followed by the specific detection of Bt11, MON810, Bt176, GA21, MON863, NK603, TC1507 (also known as DAS1507), DAS59122 and MIR604 events. The identified maize events were confirmed and quantified by real-time PCR with hydrolysis probes. The overall results of GMO screening were 30% for 35S promoter, 10% for NOS terminator and 25% for identified events. The most frequently detected events were MON810, TC1507 and NK603, with one sample containing GA21, while the other events were not detected in any of the analysed foods. The quantitative results suggest the need for a more severe control since 4% of the analysed foods contained more than the threshold for labelling and none of them declared the presence of GMO

A small universe after all?

The cosmic microwave background radiation allows us to measure both the geometry and topology of the universe. It has been argued that the COBE-DMR data already rule out models that are multiply connected on scales smaller than the particle horizon. Here we show the opposite is true: compact (small) hyperbolic universes are favoured over their infinite counterparts. For a density parameter of Omega_o=0.3, the compact models are a better fit to COBE-DMR (relative likelihood ~20) and the large-scale structure data (sigma_8 increases by ~25%).Comment: 4 pages, RevTeX, 7 Figure

DNA extraction from plant food supplements: Influence of different pharmaceutical excipients

The consumption of plant food supplements (PFS) has been growing globally, with an increase of misleading labeling and fraudulent practices also being reported. Recently, the use of molecular biology techniques has been proposed to detect botanical adulterations, one of the possible frauds in PFS. However, difficulties in recovering DNA from some PFS samples have been described. Aiming at using DNA-based methods for the unequivocal identification of plant species in PFS, adequate DNA isolation is required. However, PFS often contain pharmaceutical excipients known to have adsorbent properties that might interfere with DNA extraction. Thus, the aim of this work was to assess the effect of different excipients (talc, silica, iron oxide and titanium dioxide) on the recovery/amplification of DNA. For that purpose, known amounts of template maize DNA were spiked either to PFS or to model mixtures of excipients and quantified by real-time PCR. The tested excipients evidenced clear adsorption phenomena that justify the hampering effect on DNA extraction from PFS. The use of either 10% talc or 0.5% dyes completely adsorbed DNA, resulting in negative PCR amplifications. For the first time, pharmaceutical excipients were shown to affect DNA extraction explaining the inability of recovering DNA from some PFS samples in previous studies.This work received financial support from the European Union (FEDER funds through COMPETE) and National Funds (FCT, Fundaç~ao para a Ci^encia e Tecnologia) through project EXPL/DTPSAP/ 1438/2013 (Safety of plant food supplements: searching for adulterant pharmaceutical drugs and plants) and UID/QUI/50006/ 2013. Joana Costa and Telmo J.R. Fernandes are grateful to FCT grants SFRH/BPD/102404/2014 and SFRH/BD/93711/2013, respectively, financed by POPH-QREN (subsidized by FSE and MCTES).This work received financial support from the European Union (FEDER funds through COMPETE) and National Funds (FCT, Fundaç~ao para a Ci^encia e Tecnologia) through project EXPL/DTPSAP/ 1438/2013 (Safety of plant food supplements: searching for adulterant pharmaceutical drugs and plants) and UID/QUI/50006/ 2013. Joana Costa and Telmo J.R. Fernandes are grateful to FCT grants SFRH/BPD/102404/2014 and SFRH/BD/93711/2013, respectively, financed by POPH-QREN (subsidized by FSE and MCTES).info:eu-repo/semantics/publishedVersio

Nature of singularity formed by the gravitational collapse in Husain space-time with electromagnetic field and scalar field

In this work, we have investigated the outcome of gravitational collapse in Husain space-time in the presence of electro-magnetic and a scalar field with potential. In order to study the nature of the singularity, global behavior of radial null geodesics have been taken into account. The nature of singularities formed has been thoroughly studied for all possible variations of the parameters. These choices of parameters has been presented in tabular form in various dimensions. It is seen that irrespective of whatever values of the parameters chosen, the collapse always results in a naked singularity in all dimensions. There is less possibility of formation of a black hole. Hence this work is a significant counterexample of the cosmic censorship hypothesis.Comment: 9 pages, 19 figure

Gravitational Collapse in Higher Dimensional Husain Space-Time

We investigate exact solution in higher dimensional Husain model for a null fluid source with pressure $p$ and density $\rho$ are related by the following relations (i) $p=k\rho$, (ii) $p=k\rho-\frac{B(v)}{\rho^{\alpha}}$ (variable modified Chaplygin) and (iii) $p=k\rho^{\alpha}$ (polytropic). We have studied the nature of singularity in gravitational collapse for the above equations of state and also for different choices of the of the parameters $k$ and $B$ namely, (i) $k=0$, $B=$ constant (generalized Chaplygin), (ii) $B=$ constant (modified Chaplygin). It is found that the nature of singularity is independent of these choices of different equation of state except for variable Chaplygin model. Choices of various parameters are shown in tabular form. Finally, matching of Szekeres model with exterior Husain space-time is done.Comment: 12 latex pages, No figure, RevTex styl

An alternative order parameter for the 4-state Potts model

We have investigated the dynamic critical behavior of the two-dimensional 4-state Potts model using an alternative order parameter first used by Vanderzande [J. Phys. A: Math. Gen. \textbf{20}, L549 (1987)] in the study of the Z(5) model. We have estimated the global persistence exponent $\theta_g$ by following the time evolution of the probability $P(t)$ that the considered order parameter does not change its sign up to time $t$. We have also obtained the critical exponents $\theta$, $z$, $\nu$, and $\beta$ using this alternative definition of the order parameter and our results are in complete agreement with available values found in literature.Comment: 6 pages, 6 figure