Global Electrical Charge Research Articles

Surface and curvature properties of charged strangelets in compact objects

Droplets of absolutely stable strange quark matter (strangelets) immersed in a lepton background may be the energetically preferred composition of strange star crusts and may also constitute the interior of a new class of stellar objects known as strangelet dwarfs. In this work we calculate the surface tension $\ensuremath{\sigma}$ and the curvature coefficient $\ensuremath{\gamma}$ of charged strangelets as a function of the baryon number density, the temperature, the chemical potential of trapped neutrinos, the strangelet size, the electric potential, and the electric charge at their boundary. Strange quark matter in chemical equilibrium and with global electric charge neutrality is described within the MIT bag model. We focus on three different astrophysical scenarios, namely, cold strange stars, protostrange stars, and postmerger strange stars, characterized by the temperature and the amount of neutrinos trapped in the system. Finite-size effects are implemented within the multiple reflection expansion framework. We find that $\ensuremath{\sigma}$ decreases significantly as the strangelet's boundary becomes more positively charged. This occurs because $\ensuremath{\sigma}$ is dominated by the contribution of $s$ quarks which are the most massive particles in the system. Negatively charged $s$-quarks are suppressed in strangelets with a large positive electric charge, diminishing their contribution to $\ensuremath{\sigma}$ and resulting in smaller values of the total surface tension. We also verify that the more extreme astrophysical scenarios, with higher temperatures and higher neutrino chemical potentials, allow higher positive values of the strangelet's electric charge at the boundary and consequently smaller values of $\ensuremath{\sigma}$. In contrast, $\ensuremath{\gamma}$ is strongly dominated by the density of light ($u$ and $d$) quarks and is quite independent of the charge-per-baryon ratio, the temperature and neutrino trapping. We discuss the relative importance of surface and curvature effects as well as some astrophysical consequences of these results.

Basic Steps in Chemical Dissociation of Gaseous Molecules Using an Even-Odd Rule, a Specifically Adapted Periodic Table and a Covalent Bonding Rule

When writing equations of chemical dissociation, students and scholars are taught two fundamental rules to balance the equation. On both sides of the equation, the types of elements and their quantity are conserved, as well as the global electrical charge. This paper introduces additional methods during dissociation of gaseous compounds, to precisely describe how electrical charges locally move and how bonding structures are modified. Specific rules revolving around electrons pairs displacements are developed and applied to about 150 dissociations of small gaseous molecules using atoms from the three first rows of the periodic table. Results obtained tend to demonstrate the relevance of these tools for chemists.

Gravitational collapse of charged scalar fields

In order to study the gravitational collapse of charged matter we analyze the simple model of an self-gravitating massless scalar field coupled to the electromagnetic field in spherical symmetry. The evolution equations for the Maxwell-Klein-Gordon sector are derived in the 3+1 formalism, and coupled to gravity by means of the stress-energy tensor of these fields. To solve consistently the full system we employ a generalized Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulation of General Relativity that is adapted to spherical symmetry. We consider two sets of initial data that represent a time symmetric spherical thick shell of charged scalar field, and differ by the fact that one set has zero global electrical charge while the other has non-zero global charge. For compact enough initial shells we find that the configuration doesn't disperse and approaches a final state corresponding to a sub-extremal Reissner-N\"ordstrom black hole with $|Q|<M$. By increasing the fundamental charge of the scalar field $q$ we find that the final black hole tends to become more and more neutral. Our results support the cosmic censorship conjecture for the case of charged matter.

Quark–hadron mixed phases in protoneutron stars

We consider the possible formation of the quark–hadron mixed phase in protoneutron stars. We discuss two cases. The first one, corresponding to a vanishingly small value of the surface tension of quark matter, is the well-known mixed phase in which the global electric charge neutrality condition is imposed. In turn, this produces a non-constant pressure mixed phase. In the second case, corresponding to very large values of the surface tension, the charge neutrality condition holds only locally. However, the existence in protoneutron star matter of an additional globally conserved charge, the lepton number, allows for a new type of non-constant pressure mixed phase. We discuss the properties of the new mixed phase and the possible effects of its formation during the evolution of protoneutron stars.

Surface physicochemical analysis of natural Lactococcus lactis strains reveals the existence of hydrophobic and low charged strains with altered adhesive properties

The cell surface physicochemical properties of 50 Lactococcus lactis strains of different subspecies and isolated from different origins (dairy, vegetal and animal) were examined. Cell surface hydrophobicity and Lewis acid–base properties were evaluated by affinity measurements to solvents in a partitioning test, while the global electrical charge of the cells was assessed by micro-electrophoresis using a laser zeta-meter. A global multivariate analysis of the results revealed a high natural diversity of L. lactis cell surface properties. While 52% of the strains present a hydrophilic and electronegative cell wall surface, a group of strikingly hydrophobic strains (12% of the strains) and a group of strains with unusual low charged surface (18%) were identified. Adhesion on polystyrene microtitre plates was evaluated for twelve strains selected from the multivariate analysis as representatives of the various observed cell wall surface physicochemical patterns. A significant correlation between adhesion, hydrophobicity and low electronegativity was observed when adhesion was performed in a low ionic strength suspending medium. The most adhesive strains were hydrophobic or low charged. The presence of repulsive electrostatic interactions led to a decrease in adhesion of the most negatively charged hydrophilic strains. The present study highlights the diversity of L. lactis cell surface physicochemical properties, diversity that could not be connected to the origin or to the subspecies of the strains.

Capillary electrophoresis using copolymers of different composition as physical coatings: A comparative study

In this work, a comparative study on the use of different polymers as physically adsorbed coatings for CE is presented. It is demonstrated that the use of ad hoc synthesized polymers as coatings allows tailoring the EOF in CE increasing the flexibility of this analytical technique. Namely, different polymers were synthesized at our laboratory using different percentages of ethylpyrrolidine methacrylate (EpyM) and N,N-dimethylacrylamide (DMA). Thus, by modifying the percentage of EpyM and DMA monomers it is possible to manipulate the positive charge of the copolymer, varying the global electrical charge on the capillary wall and with that the EOF. These coated capillaries are obtained by simply flushing a given EpyM-DMA aqueous solution into bare silica capillaries. It is shown that by using these coated capillaries at adequate pHs, faster or more resolved CE separations can be achieved depending on the requirements of each analysis. Moreover, it is demonstrated that these coated capillaries reduce the electrostatic adsorption of basic proteins onto the capillary wall. Furthermore, EpyM-DMA coatings allow the reproducible chiral separation of enantiomers through the partial filling technique (PFT). The EpyM-DMA coated capillaries are demonstrated to provide reproducible EOF values independently of the pH and polymer composition with%RSD values lower than 2% for the same day. It is also demonstrated that the coating procedure is reproducible between capillaries. The compatibility of this coating protocol with CE in microchips is discussed.

Toward New Organic/Inorganic Superlattices: Keggin Polyoxometalates in Langmuir and Langmuir−Blodgett Films

The effect of Keggin heteropolyoxotungstates (XW12O40n- with X = H2, P, Si, B or Co) on Langmuir films has been studied for monolayers of DODA (dimethyldioctadecylammonium) and DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine). Marked modifications of the compression isotherms have been observed when the Keggin anions were dissolved in the subphase: this demonstrates that the polyanions interact with the monolayer. Langmuir−Blodgett (LB) films have been readily obtained from these systems (even with DPPC) for a particular range in polyanion concentration. X-ray diffraction and infrared dichroism experiments have shown a well-defined lamellar structure for these built-up films as well as the presence within the LB films of polyoxometalates organized in monolayers. Control of the Keggin polyanion amount in the multilayers is made possible by mixing DODA with a negatively charged lipid, which modifies the global electrical charge of the Langmuir film. Such an organic−inorganic system leads to new ultrathin materials having various properties related to the selected polyanions.

Mixed monolayers of phosphatidylethanolamine and (laurylamido)-N,N'-dimethylpropylamine oxide at the air/water interface. Lateral proton conduction along a mixed structure of conducting and nonconducting entities

A localized lateral proton pathway is present along the phospholipid polar heads and bound water molecules when the lipids are spread in monolayers at the air/water interface. Mixed films of (laurylamino)-N-N'-dimethylpropylamine oxide (LAPOA) and phosphatidylethanolamine (PE) are studied by surface pressure and fluorescene measurements. The polar head of this amphiphilic detergent shows no global electric charge but a N + ←O - dipole. The localization of this detergent at the air/water interface changes when the mixed monolayer is compressed