This paper reports the effect of sol size on nanofiltration performances of sol–gel derived microporous zirconia membranes. Microstructure, pure water flux, molecular weight cut-off(MWCO) and salt retention of zircon...This paper reports the effect of sol size on nanofiltration performances of sol–gel derived microporous zirconia membranes. Microstructure, pure water flux, molecular weight cut-off(MWCO) and salt retention of zirconia membranes derived from zirconia sols with different sizes were characterized. Thermal evolution, phase composition, microstructure and chemical stability of unsupported zirconia membranes(powder) were determined by thermogravimetric and differential thermal analysis, X-ray diffraction, nitrogen adsorption–desorption and static solubility measurements. Results show that nanofiltration performance of zirconia membranes is highly dependent on sol size. The sol with an average size of 3.8 nm, which is smaller than the pore size of the γ-Al2O3support(pore size: 5–6 nm), forms a discontinuous zirconia separation layer because of excessive penetration of sol into the support. This zirconia membrane displays a MWCO value towards polyethylene glycol higher than 4000 Da. A smooth and defect-free zirconia membrane with a MWCO value of 1195 Da(pore size: 1.75 nm) and relative high retention rates towards Mg Cl2(76%) and Ca Cl2(64%) was successfully fabricated by dip-coating the sol with an appropriate size of 8.6 nm. Zirconia sol with an average size of 12 nm exhibits colloidal nature and forms a zirconia membrane with a MWCO value of 2332 Da(pore size: 2.47 nm). This promising microporous zirconia membrane presents sufficiently high chemical stability in a wide p H range of 1–12.展开更多
The post-modernist concerning with identity and subjectivity posits that identity is multi-faceted and constantly gets re-constructed by choice. This results in increasingly fragmented and unstable identities leading ...The post-modernist concerning with identity and subjectivity posits that identity is multi-faceted and constantly gets re-constructed by choice. This results in increasingly fragmented and unstable identities leading to an inevitable breakdown in social relationships and sanity. A limited and dependable set of coherent identities began to fragment into a diverse and unstable series of competing identities. Post-modernism stifled the idea of nation, religion, family, and identity as bedrocks of stability and security. Disillusioned post-modernist world has deconstructed the well-defined boundaries that governed the life, otherwise, transition and transgression through and across these domains became the norm that allowed negotiation in daily lives. Where the subject became a terminal of multiple networks, consciously enacting the repetitions through which identity was getting produced and changed, demonstrating identity＇s ＂performativity＂. Establishing that what we believe to be true is only a construction or an interpretation of reality, shaped by our own socially constructed bias, thereby putting to scrutiny the idea of reality and real itself, which removed any sense of objective reality and with it the notion of an objective self. Identity is constantly changing and transitioning, the idea of the self which is entangled with multiplicity, heterogeneity, difference and ceaselessly becoming caught between the present and future, real and unreal, death and life. This research paper will carry out an analysis on evidential aspects in the selected novel and will further interpret the episodes of transition and transgressions that inform this novel.展开更多
In this paper, a differential equation with piecewise constant arguments modeling an early brain tumor growth is considered. The discretization process in the interval t ∈ [n, n＋1） leads to two-dimensional discrete...In this paper, a differential equation with piecewise constant arguments modeling an early brain tumor growth is considered. The discretization process in the interval t ∈ [n, n＋1） leads to two-dimensional discrete dynamical system. By using the Schur-Cohn criterion, stability conditions of the positive equilibrium point of the system are obtained. Choosing appropriate bifurcation parameter, the existence of Neimark-Sacker and flip bifurcations is verified. In addition, the direction and stability of the Neimark-Sacker and flip bifurcations are determined by using the normal form and center manifold theory. Finally, the Lyapunov exponents are numerically computed to characterize the complexity of the dynamical behaviors of the system.展开更多
基金Supported by the National Natural Science Foundation of China(20906047,21276123)the National High Technology Research and Development Program of China(2012AA03A606)+3 种基金State Key Laboratory of Materials-Oriented Chemical Engineering(ZK201002)the Natural Science Research Plan of Jiangsu Universities(11KJB530006)the"Summit of the Six Top Talents"Program of Jiangsu Provincea Project Funded by the Priority Academic Program development of Jiangsu Higher Education Institutions(PAPD)
文摘This paper reports the effect of sol size on nanofiltration performances of sol–gel derived microporous zirconia membranes. Microstructure, pure water flux, molecular weight cut-off(MWCO) and salt retention of zirconia membranes derived from zirconia sols with different sizes were characterized. Thermal evolution, phase composition, microstructure and chemical stability of unsupported zirconia membranes(powder) were determined by thermogravimetric and differential thermal analysis, X-ray diffraction, nitrogen adsorption–desorption and static solubility measurements. Results show that nanofiltration performance of zirconia membranes is highly dependent on sol size. The sol with an average size of 3.8 nm, which is smaller than the pore size of the γ-Al2O3support(pore size: 5–6 nm), forms a discontinuous zirconia separation layer because of excessive penetration of sol into the support. This zirconia membrane displays a MWCO value towards polyethylene glycol higher than 4000 Da. A smooth and defect-free zirconia membrane with a MWCO value of 1195 Da(pore size: 1.75 nm) and relative high retention rates towards Mg Cl2(76%) and Ca Cl2(64%) was successfully fabricated by dip-coating the sol with an appropriate size of 8.6 nm. Zirconia sol with an average size of 12 nm exhibits colloidal nature and forms a zirconia membrane with a MWCO value of 2332 Da(pore size: 2.47 nm). This promising microporous zirconia membrane presents sufficiently high chemical stability in a wide p H range of 1–12.
文摘The post-modernist concerning with identity and subjectivity posits that identity is multi-faceted and constantly gets re-constructed by choice. This results in increasingly fragmented and unstable identities leading to an inevitable breakdown in social relationships and sanity. A limited and dependable set of coherent identities began to fragment into a diverse and unstable series of competing identities. Post-modernism stifled the idea of nation, religion, family, and identity as bedrocks of stability and security. Disillusioned post-modernist world has deconstructed the well-defined boundaries that governed the life, otherwise, transition and transgression through and across these domains became the norm that allowed negotiation in daily lives. Where the subject became a terminal of multiple networks, consciously enacting the repetitions through which identity was getting produced and changed, demonstrating identity＇s ＂performativity＂. Establishing that what we believe to be true is only a construction or an interpretation of reality, shaped by our own socially constructed bias, thereby putting to scrutiny the idea of reality and real itself, which removed any sense of objective reality and with it the notion of an objective self. Identity is constantly changing and transitioning, the idea of the self which is entangled with multiplicity, heterogeneity, difference and ceaselessly becoming caught between the present and future, real and unreal, death and life. This research paper will carry out an analysis on evidential aspects in the selected novel and will further interpret the episodes of transition and transgressions that inform this novel.
文摘In this paper, a differential equation with piecewise constant arguments modeling an early brain tumor growth is considered. The discretization process in the interval t ∈ [n, n＋1） leads to two-dimensional discrete dynamical system. By using the Schur-Cohn criterion, stability conditions of the positive equilibrium point of the system are obtained. Choosing appropriate bifurcation parameter, the existence of Neimark-Sacker and flip bifurcations is verified. In addition, the direction and stability of the Neimark-Sacker and flip bifurcations are determined by using the normal form and center manifold theory. Finally, the Lyapunov exponents are numerically computed to characterize the complexity of the dynamical behaviors of the system.
