Inversion of DNA charge by a positive polymer via fractionalization of the polymer charge

Charge inversion of a DNA double helix by an oppositely charged flexible polyelectrolyte (PE) is widely used for gene delivery. It is considered here in terms of discrete charges of DNA. We concentrate on the worst scenario case when in the neutral state of the DNA-PE complex, each of the DNA charges is locally compensated by a PE charge and show that charge inversion exists even in this case. When an additional PE molecule is adsorbed by DNA, its charge gets fractionalized into monomer charges of defects (tails and arches) on the background of the perfectly neutralized DNA. These charges spread all over the DNA eliminating the self-energy of PE. Fractionalization leads to a substantial charge inversion of DNA. We show that fractionalization mechanism charge inversion works also for nonlinear polymers such as dendrimers. Remarkably, such fractionalization happens for adsorption of both PE or dendrimers on a two-dimensional charged lattice, as well. Relation of fractionalization to other mechanisms of charge inversion is discussed.Comment: Accepted for publication in Physica

Complexation of DNA with positive spheres: phase diagram of charge inversion and reentrant condensation

The phase diagram of a water solution of DNA and oppositely charged spherical macroions is studied. DNA winds around spheres to form beads-on-a-string complexes resembling the chromatin 10 nm fiber. At small enough concentration of spheres these "artificial chromatin" complexes are negative, while at large enough concentrations of spheres the charge of DNA is inverted by the adsorbed spheres. Charges of complexes stabilize their solutions. In the plane of concentrations of DNA and spheres the phases with positive and negative complexes are separated by another phase, which contains the condensate of neutral DNA-spheres complexes. Thus when the concentration of spheres grows, DNA-spheres complexes experience condensation and resolubilization (or reentrant condensation). Phenomenological theory of the phase diagram of reentrant condensation and charge inversion is suggested. Parameters of this theory are calculated by microscopic theory. It is shown that an important part of the effect of a monovalent salt on the phase diagram can be described by the nontrivial renormalization of the effective linear charge density of DNA wound around a sphere, due to the Onsager-Manning condensation. We argue that our phenomenological phase diagram or reentrant condensation is generic to a large class of strongly asymmetric electrolytes. Possible implication of these results for the natural chromatin are discussed.Comment: Many corrections to text. SUbmitted to J. Chem. Phy

An Investigation into Value Co-creation in Service Supply Chains

In service supply chains, customers select a service provider with whom value would be maximized through the interaction between the service provider and the customer. This study investigates the link between value co-creation and customers’ (re)purchasing intentions in the financial and professional services industry. This research was conducted via a case study of PricewaterhouseCoopers (PwC) and one of its clients, Jaguar Land Rover (JLR) and included in-depth interviews with senior managers. The findings underline that the financial and professional services industry is dominated by end of service results and that the only viable option in gaining competitive advantage is to stand out in today’s dynamic marketplace. It also reveals that there is a huge demand for outsourcing services and that most clients will choose to purchase one which offers the desired value at the right time. Lastly, it proposes a value co-creation framework derived from the study

Spherical Colloids: Effect of Discrete Macroion Charge Distribution and Counterion Valence

We report the coupled effects of macroion charge discretization and counterion valence in the primitive model for spherical colloids. Instead of considering a uniformly charged surface, as it is traditionally done, we consider a more realistic situation where \textit{discrete monovalent microscopic charges} are randomly distributed over the sphere. Monovalent or multivalent counterions ensure global electroneutrality. We use molecular dynamics simulations to study these effects at the ground state and for finite temperature. The ground state analysis concerns the counterion structure and \textit{charge inversion}. Results are discussed in terms of simple analytical models. For finite temperature, strong and weak Coulomb couplings are treated. In this situation of finite temperature, we considered and discussed the phenomena of ionic pairing (pinning) and unpairing (unpinning).Comment: 24 pages, 12 (main) figures (28 EPS files). To appear in Physica

Dichlorido[(R,R)-N 1,N 1,N 2-tribenzyl­cyclo­hexane-1,2-diamine-κ2 N 1,N 2]copper(II)

In the title compound, [CuCl2(C27H32N2)], which bears a chiral diamine ligand, viz (R,R)-N,N,N′′- tribenzyl­cyclo­hexane-1,2-diamine, the CuII ion is ligated by two N and two Cl atoms in a distorted square-planar geometry. The coordination of the ligands to the CuII ion results in the formation of a five-membered heterocyclic ring and a chiral center at the monosubstituted nitro­gen in an (S)-configuration. The catalytic capacity of the complex for the asymmetric nitro­aldol reaction is promising (49% ee)

Chevalier Jackson, M.D. (1865-1958): Il ne se repose jamais.

In the final year of the American Civil War, 1865, Chevalier Jackson was born on the 4th of November just outside Pittsburgh, Pennsylvania. The eldest of three sons of a poor, livestock-raising family, Jackson was raised in a period of social and political unrest. He was perhaps an even more unrestful boy. The description of his childhood days from his father’s father—Il ne se repose jamais, ‘‘He never rests’’—would ultimately reflect the man, doctor, and evangelist Jackson would later become.1 Indeed, he never did rest, Jackson would tirelessly pave the way for modern bronchoscopy and endoscopy as a whole; bringing international renown not only to himself, but also to his specialty

A new method for large time behavior of degenerate viscous Hamilton--Jacobi equations with convex Hamiltonians

We investigate large-time asymptotics for viscous Hamilton--Jacobi equations with possibly degenerate diffusion terms. We establish new results on the convergence, which are the first general ones concerning equations which are neither uniformly parabolic nor first order. Our method is based on the nonlinear adjoint method and the derivation of new estimates on long time averaging effects. It also extends to the case of weakly coupled systems

Supporting information needs of senior citizens in community aged care

To address the challenge of an ageing population in an information society, it is important to introduce information systems to assist the aged people in maintaining and improving their quality of life. An understanding of what information aged people need, how they seek and use information, and how they adopt Information and Communication Technology (ICT) is required. This paper reports the findings of an empirical study undertaken in Australia to understand the information needs of senior citizens who reside in the community. The study aims to understand how ICT can support the independent living of senior people in the community from both the social and health perspectives. We offer a new understanding of the information needs of aged people in the community and extend the information systems research in aged care. This research also contributes to the development of innovative ICT enabled aged care service solutions in community aged care.<br /