22 research outputs found
Dehydration and ionic conductance quantization in nanopores
There has been tremendous experimental progress in the last decade in
identifying the structure and function of biological pores (ion channels) and
fabricating synthetic pores. Despite this progress, many questions still remain
about the mechanisms and universal features of ionic transport in these
systems. In this paper, we examine the use of nanopores to probe ion transport
and to construct functional nanoscale devices. Specifically, we focus on the
newly predicted phenomenon of quantized ionic conductance in nanopores as a
function of the effective pore radius - a prediction that yields a particularly
transparent way to probe the contribution of dehydration to ionic transport. We
study the role of ionic species in the formation of hydration layers inside and
outside of pores. We find that the ion type plays only a minor role in the
radial positions of the predicted steps in the ion conductance. However, ions
with higher valency form stronger hydration shells, and thus, provide even more
pronounced, and therefore, more easily detected, drops in the ionic current.
Measuring this phenomenon directly, or from the resulting noise, with synthetic
nanopores would provide evidence of the deviation from macroscopic (continuum)
dielectric behavior due to microscopic features at the nanoscale and may shed
light on the behavior of ions in more complex biological channels.Comment: 13 pages, 10 figure
Nutrition and cancer: A review of the evidence for an anti-cancer diet
It has been estimated that 30–40 percent of all cancers can be prevented by lifestyle and dietary measures alone. Obesity, nutrient sparse foods such as concentrated sugars and refined flour products that contribute to impaired glucose metabolism (which leads to diabetes), low fiber intake, consumption of red meat, and imbalance of omega 3 and omega 6 fats all contribute to excess cancer risk. Intake of flax seed, especially its lignan fraction, and abundant portions of fruits and vegetables will lower cancer risk. Allium and cruciferous vegetables are especially beneficial, with broccoli sprouts being the densest source of sulforophane. Protective elements in a cancer prevention diet include selenium, folic acid, vitamin B-12, vitamin D, chlorophyll, and antioxidants such as the carotenoids (α-carotene, β-carotene, lycopene, lutein, cryptoxanthin). Ascorbic acid has limited benefits orally, but could be very beneficial intravenously. Supplementary use of oral digestive enzymes and probiotics also has merit as anticancer dietary measures. When a diet is compiled according to the guidelines here it is likely that there would be at least a 60–70 percent decrease in breast, colorectal, and prostate cancers, and even a 40–50 percent decrease in lung cancer, along with similar reductions in cancers at other sites. Such a diet would be conducive to preventing cancer and would favor recovery from cancer as well