Micro and nanoscale mobile agents capable of self-propulsion in low Reynolds number fluids would have a great technological impact in many fields. Few known mechanisms are able to propel such devices. Here we describe helical nanobelt (HNB) swimmers actuated by an electric field-generated electro-osmotic force. These HNB swimmers are designed with a head and a tail, similar to natural micro-org...

It is well known that the plasma membranes of mammalian spermatozoa undergo extensive remodeling during maturation in the epididymal duct. In this investigation, we have used fluorescence recovery after photobleaching (FRAP) techniques to: 1) measure rates of lipid diffusion in the plasma membrane of mouse spermatozoa at different stages of maturation; 2) examine the effects of varying external...

Microtubules (MTs) are hollow cylindrical polymers composed of alphabeta-tubulin heterodimers that align head-to-tail in the MT wall, forming linear protofilaments that interact laterally. We introduce a probe of the interprotofilament interactions within MTs and show that this technique gives insight into the mechanisms by which MT-associated proteins (MAPs) and taxol stabilize MTs. In additio...

We propose a model for the liquid-liquid (L(alpha)-->L(alpha(') )) phase transition observed in osmotic pressure measurements of certain charged lamellae-forming amphiphiles. The model free energy combines mean-field electrostatic and phenomenological nonelectrostatic interactions, while the number of dissociated counterions is treated as a variable degree of freedom that is determined self-con...

A model for self-propulsion of a colloidal particle--the osmotic motor--immersed in a dispersion of "bath" particles is presented. The nonequilibrium concentration of bath particles induced by a surface chemical reaction creates an osmotic pressure imbalance on the motor causing it to move. The ratio of the speed of reaction to that of diffusion governs the bath particle distribution which is e...

background: recurrent abortion is defined as three or more consecutive pregnancy losses. we aimed to determine the relationship between male sperm parameters and hypo-osmotic swelling score and recurrent abortion. we also studied whether washing of spermatozoa and intrauterine insemination in patients with recurrent miscarriage and low score hypo-osmotic swelling test in male partners could imp...

BACKGROUND Although the effects of opioids on intracranial pressure (ICP) have long been a subject of controversy, they are frequently administered to patients with severe head trauma. We present a patient with an uncommon paradoxical response to opioids. CASE REPORT A patient with refractory intracranial hypertension after closed head injury was managed with standard medical therapy with onl...

Iran is located in a hot and dry region. As a result of low precipitation and a vast area of salty and alkali soil, osmotic pressure is very high in most parts of the country (i.e., osmotic potential is more negative). In the present study four levels of osmotic pressure (-0.25, -0.35, -0.45, -0.50 MPa) were created artificially, by polyethylene glycol (PEG) and treatment of three seed types, n...