Aiming to highly efficient capture and analysis of circulating tumor cells, a micropillar device decorated with graphite oxide-coated magnetic nanoparticles is developed for magneto-controllable capture and release of cancer cells. Graphite oxide-coated, Fe3 O4 magnetic nanoparticles (MNPs) are synthesized by solution mixing and functionalized with a specific antibody, following by the immobilization of such modified MNPs on our designed micropillar device. For the proof-of-concept study, a HCT116 colorectal cancer cell line is employed to exam the capture efficiency. Under magnetic field manipulation, the high density packing of antibody-modified MNPs on the micropillars increases the local concentration of antibody, as well as the topographic interactions between cancer cells and micropillar surfaces. The flow rate and the micropillar geometry are optimized by studying their effects on capture efficiency. Then, a different number of HCT116 cells spiked in two kinds of cell suspension are investigated, yielding capture efficiency >70% in culture medium and >40% in blood sample, respectively. Moreover, the captured HCT116 cells are able to be released from the micropillars with a saturated efficiency of 92.9% upon the removal of applied magnetic field and it is found that 78% of the released cancer cells are viable, making them suitable for subsequent biological analysis.

The separation and removal of oil or organic pollutants from water is highly imperative. The oil phases in surfactant-free oil-in-water emulsions or in free oil/water mixtures can be smartly enriched and transported by using superhydrophobic/superoleophilic iron particles (SHIPs) under a magnetic field. For water-in-oil emulsion, SHIPs-based composite membranes selectively allow the oil to pass through. Their convenient and scalable preparation, excellent separation performance, and good reusability are of great advantages for practical applications in wastewater treatment, the cleanup of oil spills, emulsion concentration, and fuel purification.

Abstract. Bacteria-algae interaction in the epilimnion is modeled with the explicit consideration of carbon (energy) and phosphorus (nutrient). Global qualitative analysis and bifurcation diagrams of this model are presented. We hypothesize that there are three dynamical scenarios determined by the basic reproductive numbers of bacteria and algae. Effects of key environmental conditions are examined through these scenarios and from systematic and extensive simulations. It is also shown that excessive sunlight will destroy bacterial communities. Bifurcation diagrams for the depth of epilimnion mimic the profile of Lake Biwa, Japan. Competition of bacterial strains are modeled to examine Nishimura's hypothesis that in severely P-limited environments such as Lake Biwa, P limitation exerts more severe constraints on the growth of bacterial groups with higher nucleic acid (HNA) contents, which allows low nucleic acid (LNA) bacteria to be competitive.Key words. Stoichiometry, bacteria, cell quota, persistence, competitive system 1. Introduction. Stoichiometry is the accounting behind chemistry. It deals with the balance of multiple chemical elements in chemical reactions. Many chemical processes are effectively studied and modeled with the applications of some simple yet powerful stoichiometric constraints. Since biomass growth is a biochemical process, ubiquitous and natural stoichiometric constraints may also be useful for modeling species growth and interactions ([15, 23, 27, 28]). This concept forms the framework of the newly emerging research area of ecological stoichiometry, the study of the balance of energy and multiple chemical elements in ecological interactions ([37]).It is observed that plant quality can dramatically affect the growth rate of herbivorous grazers and may even lead to their extinction. Specifically, if the quantity of an essential element in plant biomass is lower than the minimum threshold for its consumer, then the consumer's growth rate may suffer. This has been shown for both aquatic ([30, 37]), and terrestrial systems ([31]). Stoichiometry-based population models explicitly model the highly varying nutritional quality of plant resources for consumer-resource dynamics.Solar energy (for producing organic carbon) and nutrients (phosphorus, nitrogen, etc) are important factors regulating ecosystem characteristics and species density. Phosphorus is often a limiting nutrient for algal production in lakes ([11]). For example, in Lake Biwa, phosphorus is an extremely limiting element for both algal and bacterial growth. Lake Biwa is a large (surface area, 674km2 ) and deep (maximum depth, 104m) lake located in the central part of Honshu Island, Japan. Nishimura et al. (2005) used flow cytometry to examine seasonal variations in vertical distributions of bacterioplankton in Lake Biwa. They hypothesized that in severely P-limited environments such as Lake Biwa, P limitation exerts more severe constraints on the