The effects of pure multiplicative noise on stochastic resonance in an anti-tumor system modulated by a seasonal external field are investigated by using theoretical analyses of the generalized potential and numerical simulations. For optimally selected values of the multiplicative noise intensity quasisymmetry of two potential minima and stochastic resonance are observed. Theoretical results and numerical simulations are in good quantitative agreement. Chemotherapy remains a traditional option for most advanced cancer. Immunotherapy, however, is a less conventional treatment modality. Usually, chemotherapy and immunotherapy have been regarded as unrelated, so relatively little research has investigated the relationship between these two therapies. Chemotherapy kills tumor cells in a special way periodically, but immunotherapy restrains the growth of tumor cells in a more likely linear way [1,2]. Since these different responses of tumor cells to chemotherapy and immunotherapy, when taken together, they imply that there is an interesting and significative case for combining chemotherapy and immunotherapy in tumor treatment.More than ever, cancer research is now an interdisciplinary effort which requires a basic knowledge of commonly used terms, facts, issues, and concepts. In the past decade, many studies have focused on the growth law of tumor cells via dynamics approach, specially using noise dynamics [3][4][5][6][7][8][9]. Phase transition of tumor growth induced by noises is one of the most novel foundations in recent years. Another phenomenon-known as stochastic resonance (SR) -shows that adding noise to a system can sometimes improve its ability to transfer information. The basic three ingredients of stochastic resonance are a threshold, a noise source and a weak input, it is clear that stochastic resonance is a common case and generic enough to be observable in a large variety of nonlinear dynamical systems [10,11]. Thus, it is reasonable to believe that SR can also occur in a tumor dynamical system.The mean field approximate analysis is a conventional theory for SR. It is originally proposed for symmetrical bistable systems with additive noise source [12]. The improvements of the theory of SR have included monostable systems [13,14], asymmetrical systems [15] and double-noises systems [16][17], but in all these studies the system has an additive noise source and an independent external field. To pure multiplicative noise systems, especially to many complex dynamical systems, it is still far difficult to solve them exactly, thus numerical methods are comparatively convenient options to solve these complex dynamical systems [18,19].In this letter, chemotherapy and immunotherapy are joined by an anti-tumor model with three elements, which are (1) a fluctuation of growth rate, (2) an immune form, and (3) a weak seasonal modulability induced by chemotherapy. Based on the analyses on its unique stochastic differential equation and relevant Fokker-Planck equation, we investigate a new type of SR phenomenon of an...

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Monoclinic Gd2O3:Eu(3+) nanoparticles (NPs) possess favorable magnetic and optical properties for biomedical application. However, how to obtain small enough NPs still remains a challenge. Here we combined the standard solid-state reaction with the laser ablation in liquids (LAL) technique to fabricate sub-10 nm monoclinic Gd2O3:Eu(3+) NPs and explained their formation mechanism. The obtained Gd2O3:Eu(3+) NPs exhibit bright red fluorescence emission and can be successfully used as fluorescence probe for cells imaging. In vitro and in vivo magnetic resonance imaging (MRI) studies show that the product can also serve as MRI good contrast agent. Then, we systematically investigated the nanotoxicity including cell viability, apoptosis in vitro, as well as the immunotoxicity and pharmacokinetics assays in vivo. This investigation provides a platform for the fabrication of ultrafine monoclinic Gd2O3:Eu(3+) NPs and evaluation of their efficiency and safety in preclinical application.

Manipulation of upconversion (UC) emission is of particular importance for multiplexed bioimaging. Here, we precisely manipulate the UC color output by utilizing the phonon-assisted energy back transfer (EBT) process in ultra-small (sub-10 nm) Gd2O3:Yb(3+)/Er(3+) UC nanoparticles (UCNPs). We synthesized the Gd2O3:Yb(3+)/Er(3+) UCNPs by adopting the laser ablation in liquid (LAL) technique. The synthesized Gd2O3:Yb(3+)/Er(3+) UCNPs are small spherical and monoclinic structures. Continuous color-tunable (from green to red) UC fluorescence emission is achieved by increasing the concentration of Yb(3+) ions from 0 to 15 mol%. A phonon-assisted energy back transfer (EBT) process from Er(3+) ((4)S3/2 → (4)I13/2) to nearby Yb(3+) ((2)F7/2 → (2)F5/2), which can significantly enhance red emission at 672 nm and decrease green emission, is responsible for the color-tunable UC emission by increasing the Yb(3+) concentration in Gd2O3:Yb(3+)/Er(3+) UC nanoparticles.

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