Synthesis and characterization of hybrid organic-inorganic materials based on sulphonated polyamideimide and silica

The preparation of hybrid organic–inorganic membrane materials based on a sulphonated polyamideimide resin and silica filler has been studied. The method allows the sol–gel process to proceed in the presence of a high molecular weight polyamideimide, resulting in well dispersed silica nanoparticles (<50 nm) within the polymer matrix with chemical bonding between the organic and inorganic phases. Tetraethoxysilane (TEOS) was used as the silica precursor and the organosilicate networks were bonded to the polymer matrix via a coupling agent aminopropyltriethoxysilane (APTrEOS). The structure and properties of these hybrid materials were characterized via a range of techniques including FTIR, TGA, DSC, SEM and contact angle analysis. It was found that the compatibility between organic and inorganic phases has been greatly enhanced by the incorporation of APTrEOS. The thermal stability and hydrophilic properties of hybrid materials have also been significantly improved

Function Annotation of an SBP-box Gene in Arabidopsis Based on Analysis of Co-expression Networks and Promoters

The SQUAMOSA PROMOTER BINDING PROTEIN–LIKE (SPL) gene family is an SBP-box transcription family in Arabidopsis. While several physiological responses to SPL genes have been reported, their biological role remains elusive. Here, we use a combined analysis of expression correlation, the interactome, and promoter content to infer the biological role of the SPL genes in Arabidopsis thaliana. Analysis of the SPL-correlated gene network reveals multiple functions for SPL genes. Network analysis shows that SPL genes function by controlling other transcription factor families and have relatives with membrane protein transport activity. The interactome analysis of the correlation genes suggests that SPL genes also take part in metabolism of glucose, inorganic salts, and ATP production. Furthermore, the promoters of the correlated genes contain a core binding cis-element (GTAC). All of these analyses suggest that SPL genes have varied functions in Arabidopsis

Controllability and stabilization of unstable LTI systems with input saturation

In this paper, we study the controllable region of a general unstable continuous-time LTI system with input saturation and we also study the stabilization of such a system by a saturated linear state feedback. We give simple exact descriptions of the controllable regions for certain classes of unstable systems. The study on stabilization is quite preliminary. We only deal with anti-stable planar systems. We conjecture that for such a system its asymptotic stability region (domain of attraction) under a saturated linear state feedback can be easily obtained from a stable limit cycle of its time-reversed system. We conjecture with convincing arguments that for such a system a saturated linear state feedback can be designed so that the asymptotic stability region is arbitrarily close to its controllable region

Stabilization of LTI systems with planar anti-stable dynamics using saturated linear feedback

In this paper, we first, study the stabilization of an LTI anti-stable planar system with a saturated linear state feedback. We show that the domain of attraction of such a system under any saturated linear stabilizing feedback can be obtained easily by simulating the time-reversed closed-loop system. We then show that a saturated linear state feedback can be designed for such a system so that the equilibrium of the closed-loop system has a domain of attraction that is arbitrarily close to the null controllable region. Finally we present an extension of this result to general LTI systems with planar anti-stable dynamics

Dynamic analysis of fractional-order memristive chaotic system with time delay and its application in color image encryption based on DNA encoding

This paper proposes a fractional-order delayed memristive chaotic system and studies its dynamic analysis, and then a color image is encrypted based on the chaotic system and DNA encoding. First, the stability and bifurcation behaviors of the fractional-order memristive chaotic system with time delay are investigated and some sufficient conditions of the stability are obtained. Second, the Largest Lyapunov exponent, bifurcation diagram and K of the 0–1 test of the novel system are calculated, and they are shown by coexisting bifurcation, coexisting attractors, coexisting plot of $$p-q$$ and so on. All of these indicate that the novel system exists the abundant dynamic characteristics. Finally, a color image encryption scheme based on the proposed system is introduced, and the security is evaluated by statistical analysis and different attacks. Numerical simulation proves the validity of the theoretical analysis and high security of the proposed image encryption scheme

Stability regions for saturated linear systems via conjugate lyapunov functions

Abstract — We use a recently developed duality theory for linear differential inclusions (LDIs) to enhance the stability analysis of systems with saturation. Based on the duality theory, the condition of stability for a LDI in terms of one Lyapunov function can be easily derived from that in terms of a Lyapunov function conjugate to the original one in the sense of convex analysis. This paper uses a particular conjugate pair, the convex hull of quadratics and the maximum of quadratics, along with their dual relationship, for the purpose of estimating the domain of attraction for systems with saturation nonlinearities. To this end, the nonlinear system is locally transformed into a LDI system with an effective approach which enables optimization on the local LDI description. The optimization problems are derived for both the convex hull and the max functions, and the domain of attraction is estimated with both the convex hull of ellipsoids and the intersection of ellipsoids. A numerical example demonstrates that the estimation of the domain of attraction by this paper’s methods drastically improve those by the earlier methods

Human neutrophil peptide 3 could be functionally expressed in Rhodobacter sphaeroides

Human neutrophil peptides (HNPs) possess high antimicrobial activities against a broad spectrum of microorganisms. Rhodobacter sphaeroides is the best-characterized photosynthetic bacterium and exhibits potential as a novel expression system. Up to date, no literature has been reported regarding expression of HNP3 in Rb. sphaeroides. In the present study, the HNP3 gene fragment was amplified by SOE PCR and ligated into photosynthetic bacteria light-harvesting complex 2 (LH2) expression vector leading to HNP3 fusion protein expression vector. The HNP3 fusion protein was successfully expressed as rapidly evaluated by the LH2 characteristic peaks at ~800 nm and ~850 nm before purification and SDS/PAGE. Subsequently, the HNP3 fusion protein was purified by one-step affinity chromatography, and could be rapidly detected by the color and the spectral absorption at ~800 nm and ~850 nm before SDS/PAGE. Antimicrobial activity assay suggested that the HNP3 fusion protein exhibited high antimicrobial activity towards E. coli. The present study may supply an insight into employing the novel Rb. sphaeroides expression system, exhibiting dramatic advantages over currently used commercial expression system, to heterologously express human neutrophil peptides