In this work, silica nanoparticles covered with an initiator silane were grafted with novel biocompatible and functionalizable zwitterionic poly[[3-(acryloylamino)propyl](2-carboxyethyl)dimethylammonium] (polyCBAA) via atomic transfer radical polymerization. The stability of these particles in protein solutions and their functionalization were investigated. Dynamic light scattering and transmission electron microscopy were employed to characterize these particles. Results indicate that the polyCBAA-modified nanoparticles are stable for at least 72 h in both negative and positive protein solutions. The size distribution remains the same before and after protein incubation. Moreover, our results show that polyCBAA-modified silica nanoparticles can be easily functionalized. This makes these particles ideal candidates for future applications in targeted drug delivery and diagnostics in complex media.

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Surficial slope failures in residual soils are common in tropical and subtropical regions as a result of rainfall infiltration. This study develops an analytical solution for simulating rainfall infiltration into an infinite unsaturated soil slope. The analytical solution is based on the general partial differential equation for water flow through unsaturated soils. It can accept soil-water characteristic curve and unsaturated permeability function of the exponential form into account. Numerical simulations are conducted to verify the assumptions of the analytical solution and demonstrate that the proposed analytical solution is acceptable for the coarse soils with low air entry values. The pore-water pressure (pwp) distributions obtained from the analytical solution can be incorporated into a limit equilibrium method to do infinite slope stability analysis for a rain-induced shallow slip. The analysis method takes into account the influence of the water content change on unit weight and hence on factor of safety. A series of analytical parametric analyses have been performed using the developed model. The analyses indicate that when the residual soil slope, consisting of a completely decomposed granite layer underlain by a less permeable layer, is subjected to a continuous heavy rainfall, the loss of negative pwp and the reduction in factor of safety were found to be most significant for the shallow soil layer and during the first 12 h. The antecedent and subsequent rainfall intensity, depth of a less permeable layer and slope angle all have a significant influence on the pwp response and hence the slope stability.

Background The deviation of the observed frequency of a word w from its expected frequency in a given sequence x is used to determine whether or not the word is avoided. This concept is particularly useful in DNA linguistic analysis. The value of the deviation of w, denoted by , effectively characterises the extent of a word by its edge contrast in the context in which it occurs. A word w of length is a -avoided word in x if , for a given threshold . Notice that such a word may be completely absent from x. Hence, computing all such words naïvely can be a very time-consuming procedure, in particular for large k.Results In this article, we propose an -time and -space algorithm to compute all -avoided words of length k in a given sequence of length n over a fixed-sized alphabet. We also present a time-optimal -time algorithm to compute all -avoided words (of any length) in a sequence of length n over an integer alphabet of size . In addition, we provide a tight asymptotic upper bound for the number of -avoided words over an integer alphabet and the expected length of the longest one. We make available an implementation of our algorithm. Experimental results, using both real and synthetic data, show the efficiency and applicability of our implementation in biological sequence analysis.ConclusionsThe systematic search for avoided words is particularly useful for biological sequence analysis. We present a linear-time and linear-space algorithm for the computation of avoided words of length k in a given sequence x. We suggest a modification to this algorithm so that it computes all avoided words of x, irrespective of their length, within the same time complexity. We also present combinatorial results with regards to avoided words and absent words.

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Two-dimensional (2D) multiferroics attract intensive investigations because of underlying science and their potential applications. Although many 2D systems have been observed/predicted to be ferroelectric or ferromagnetic, 2D materials with both ferroic properties are still scarce. By using first-principles calculations, we predict that hole-doping can induce robust ferromagnetism in 2D ferroelectric α-In2Se3 due to its unique flat band structure, and the Curie temperature (TC) can be much higher than room temperature. Moreover, the doping concentration, strain, and number of layers can effectively modulate the magnetic moment and the TC of the material. Interestingly, strong magnetoelectric coupling is found at the surface of hole doped multilayer α-In2Se3, which allows non-volatile electric control of magnetization. Our work provides a feasible approach for designing/searching 2D multiferroics with great potential in future device applications, such as memory devices and sensors.

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