Adsorption assisted translocation of a chain molecule through a pore in a spherical vesicle

We analyze the free energy for translocation of a polymer from the outside of a spherical vesicle to the inside. The process is assumed to be driven by the adsorption of the polymer on the inner surface of the vesicle. We argue that in the case where the polymer is adsorbed on the outer surface too, the entropic barrier for translocation is absent. We analyze the adsorption energy and find the free energy profile for the process. We argue that the motion corresponds to a polymer crossing a region with a change in free energy per segment. Based upon our earlier analsis of the behaviour of kinks in such a problem, we conclude that the translocation can occur with a crossing time $t_{cross}\sim N$

Excitation energy transfer from dye molecules to doped graphene

Recently, we have reported theoretical studies (J. Chem. Phys. 129, 054703, 2008 and J. Chem. Phys. 130, 086101, 2009) on the rate of energy transfer from an electronically excited molecule to graphene. It was found that graphene is a very efficient quencher of the electronically excited states and that the rate $\propto$ $(distance)^{-4}$. The process was found to be effective up to $30\;nm$ which is well beyond the traditional FRET limit. In this report, we study the transfer of an amount of energy $\hbar \Omega$ from a dye molecule to doped graphene. We find a crossover of the distance dependence of the rate from $(distance)^{-4}$ to exponential as the Fermi level is increasingly shifted into the conduction band, with the crossover occurring at a shift of the Fermi level by an amount $\hbar \Omega/2$.Comment: This paper was submitted to J. Chem. Phys. on 20/05/201

The experiences of medical students and junior doctors with dyslexia: a survey study

Little research exists concerning dyslexia in medical education. A qualitative study highlighted issues such as bullying and a lack of support. This project aimed to quantify those findings. An online survey was sent to junior doctors in parts of the United Kingdom. Seventy-five participated. Most (53%) were diagnosed with dyslexia at university / medical school. Most reported that dyslexia impacted upon their self-image (59%) and self-esteem (73%). Nearly half (46%) felt it influenced their career pathway choices within medicine. Participants reported bullying at medical school-from peers (24%), from academic teachers (14%), and from clinical teachers (27%); and also at work-from peers (25%), from academic teachers (13%), and from clinical teachers (23%). 88% reported that foundation schools provided no support, 92% that NHS Trusts provided none, and 90% that their deaneries provided none. The sorts of supports which seemed to be lacking were "psychological" or "pastoral" supports

A simple model for the kinetics of packaging of DNA in to a capsid against an external force

We propose a simple model for the kinetics of packaging of viral DNA in to a capsid against an external force trying to prevent it. The model leads to a Butler-Volmer type dependence of the rate of packaging on the pulling force F

Theoretical design for a light-driven molecular motor based on rotaxanes

We suggest a design for a light-driven molecular motor, which is different from the existing designs. It is a rotaxane molecule, having identical 'stations' and an asymmetric 'shuttle'. We argue that the molecule would exhibit unidirectional rotational/translational motion continuously, upon shining with light of just one frequency. With this design, it should be possible to synthesizea light-driven single-molecular motor in the near future

Resonance energy transfer from a fluorescent dye molecule to plasmon and electron-hole excitations of a metal nanoparticle

We study the distance dependence of the rate of electronic excitation energy transfer from a dye molecule to a metal nanoparticle. Using the spherical jellium model, we evaluate the rates corresponding to the excitation of l = 1, 2, and 3 modes of the nanoparticle. Our calculation takes into account both the electron-hole pair and the plasmon excitations of the nanoparticle. The rate follows conventional R^-6 dependence at large distances while small deviations from this behavior are observed at shorter distances. Within the framework of the jellium model, it is not possible to attribute the experimentally observed d^-4 dependence of the rate to energy transfer to plasmons or e-h pair excitations.Comment: 4 figure

Molecular ratchets - verification of the principle of detailed balance

We argue that the recent experiments of Kelly et. al.(Angew. Chem. Int. Ed. Engl. 36, 1866 (1997)) on molecular ratchets, in addition to being in agreement with the second law of thermodynamics, is a test of the principle of detailed balance for the ratchet. We suggest new experiments, using an asymmetric ratchet, to further test the principle. We also point out methods involving a time variation of the temperature to to give it a directional motion