Spacer structure and hydrophobicity influences transfection activity of novel polycationic gemini amphiphiles

Three novel polycationic gemini amphiphiles with different spacers were developed and evaluated in terms of their physiochemical properties and transfection efficiencies. Cationic liposomes formed by these amphiphiles and the helper lipid DOPE were able to successfully condense DNA, as shown by gel mobility shift and ethidium bromide intercalation assays. Transfection activity of the liposomes was superior to Lipofectamine^® 2000 and was dependent on spacer structure, hydrophobicity, and nucleic acid type (pDNA or siRNA). We demonstrated that the cationic liposomes 2X6/DOPE and 2X7/DOPE are potential non-toxic vehicles for gene delivery.     

Role of electric discharges in the generation of atmospheric vortices

The existing thermohydrodynamic and hydroelectromagnetic models of tornado are considered. The potentialities of the humid atmosphere as a heat engine generating air vortices are analyzed in detail. The ability of long-term atmospheric electric discharges to form a tornado funnel and create an initial twist of up to 10^–3–10^–2 s^–1 in it are estimated. The possible effect of a lightning discharge on the initiation and evolution of the tornado is discussed. It is shown that the electric current flowing along the lightning channel can lead to helical instability and generation of a weak primary vortex. The channel formed in the atmosphere by a lightning discharge and the vortex motion of the parent thundercloud can enhance the primary vortex and promote its transformation into a tornado. Possible mechanisms of enhancement of the primary vortex created by a lightning discharge and the possibility of its transformation into a tornado in the postdischarge stage are discussed.     

“Enmity Rather Than a Competition”

The sorts of great minds capable of major scientific breakthroughs often come with oversized and confrontational personalities. Both Ivan Pavlov and Vladimir Bekhterev had such personalities. What started as reasoned contention between two talented scholars grew into a heated rivalry that boiled over into science and public life as outright enmity. Using memoirs of their contemporaries, this article examines Pavlov's and Bekhterev's personal and scientific relationships against the backdrop of Russian science of their day. Pavlov's possible role in the decision not to grant the 1912 Nobel Prize for science is also described.     

MHD Simulation of Physical Processes in Spherical Plasma-Focus Chambers with Allowance for Neutron Generation

Plasma Physics Reports - The results of the development of a two-dimensional MHD code for carrying out computational studies of the dynamics of plasma current sheath in spherical chambers with a...     

Diversity Waves in Collapse-Driven Population Dynamics

Populations of species in ecosystems are often constrained by availability of resources within their environment. In effect this means that a growth of one population, needs to be balanced by comparable reduction in populations of others. In neutral models of biodiversity all populations are assumed to change incrementally due to stochastic births and deaths of individuals. Here we propose and model another redistribution mechanism driven by abrupt and severe reduction in size of the population of a single species freeing up resources for the remaining ones. This mechanism may be relevant e.g. for communities of bacteria, with strain-specific collapses caused e.g. by invading bacteriophages, or for other ecosystems where infectious diseases play an important role. The emergent dynamics of our system is characterized by cyclic ‘‘diversity waves’’ triggered by collapses of globally dominating populations. The population diversity peaks at the beginning of each wave and exponentially decreases afterwards. Species abundances have bimodal time-aggregated distribution with the lower peak formed by populations of recently collapsed or newly introduced species while the upper peak - species that has not yet collapsed in the current wave. In most waves both upper and lower peaks are composed of several smaller peaks. This self-organized hierarchical peak structure has a long-term memory transmitted across several waves. It gives rise to a scale-free tail of the time-aggregated population distribution with a universal exponent of 1.7. We show that diversity wave dynamics is robust with respect to variations in the rules of our model such as diffusion between multiple environments, species-specific growth and extinction rates, and bet-hedging strategies.     

The Significance of NO-Synthase,Reactive Oxygen Species,Kinases and KATP-Channels in the Development of the Infarct-Limiting Effect of Adaptation to Hypoxia

Journal of Evolutionary Biochemistry and Physiology - The cardioprotective effect of chronic hypoxia (CH) is associated with the activation of inducible nitric oxide synthase (iNOS). Reactive...