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81.
Schmidt S Liu T Rütten S Phan KH Möller M Richtering W 《Langmuir : the ACS journal of surfaces and colloids》2011,27(16):9801-9806
Charged poly(N-isopropylacrylamide-co-methacrylic acid) [P(NiPAM-co-MAA)] microgels can stabilize thermo- and pH-sensitive emulsions. By placing charged units at different locations in the microgels and comparing the emulsion properties, we demonstrate that their behaviors as emulsion stabilizers are very different from molecular surfactants and rigid Pickering stabilizers. The results show that the stabilization of the emulsions is independent of electrostatic repulsion although the presence and location of charges are relevant. Apparently, the charges facilitate emulsion stabilization via the extent of swelling and deformability of the microgels. The stabilization of these emulsions is linked to the swelling and structure of the microgels at the oil-water interface, which depends not only on the presence of charged moieties and on solvent polarity but also on the microgel (core-shell) morphology. Therefore, the internal soft and porous structure of microgels is important, and these features make microgel-stabilized emulsions characteristically different from classical, rigid-particle-stabilized Pickering emulsions, the stability of which depends on the surface properties of the particles. 相似文献
82.
Droplet synthesis of well-defined block copolymers using solvent-resistant microfluidic device 总被引:1,自引:0,他引:1
Well-defined diblock copolymers were synthesized via an exothermic RAFT route by a droplet microfluidic process using a solvent-resistant and thermally stable fluoropolymer microreactor fabricated by a non-lithographic embedded template method. The resulting polymers were compared to products obtained from continuous flow capillary reactor and conventional bulk synthesis. The droplet based microreactor demonstrated superior molecular weight distribution control by synthesizing a higher molecular weight product with higher conversion and narrow polydispersity in a much shorter reaction time. The high quality of the as-synthesized block copolymer PMMA-b-PS led to a generation of micelles with a narrow size distribution that could be used as a template for well-ordered mesoporous silica with regular frameworks and high surface areas. 相似文献
83.
An accurate estimation of binding free energy of a ligand to receptor ΔG(bind) is one of the most important problems in drug design. The success of solution of this problem is expected to depend on force fields used for modeling a ligand-receptor complex. In this paper, we consider the impact of four main force fields, AMBER99SB, CHARMM27, GROMOS96 43a1, and OPLS-AA/L, on the binding affinity of Oseltamivir carboxylate to the wild-type and Y252H, N294S, and H274Y mutants of glycoprotein neuraminidase from the pandemic A/H5N1 virus. Having used the molecular mechanic-Poisson-Boltzmann surface area method, we have shown that ΔG(bind), obtained by AMBER99SB, OPLS-AA/L, and CHARMM27, shows the high correlation with the available experimental data. They correctly capture the binding ranking Y252H → WT → N294S → H274Y observed in experiments (Collins, P. J. et al. Nature 2008, 453, 1258). In terms of absolute values of binding scores, results obtained by AMBER99SB are in the nearest range with experiments, while OPLS-AA/L, which is applied to study binding of Oseltamivir to the influenza virus for the first time, gives rather big negative values for ΔG(bind). GROMOS96 43a1 provides a lower correlation as it supports Oseltamivir to be more resistant to N294S than H274Y. Our study suggests that force fields have pronounced influence on theoretical estimations of binding free energy of a ligand to receptor. The effect of all-atom models on dynamics of the binding pocket as well as on the hydrogen-bond network between Oseltamivir and receptors is studied in detail. The hydrogen network, obtained by GROMOS, is weakest among four studied force fields. 相似文献
84.
Determination of the structure of heparin-derived oligosaccharides by 1H NMR is challenging because resonances for all but the anomeric protons cover less than 2 ppm. By taking advantage of increased
dispersion of resonances for the anomeric H1 protons at low pD and the superior resolution of band-selective, homonuclear-decoupled (BASHD) two-dimensional 1H NMR, the primary structure of the heparin-derived octasaccharide ∆UA(2S)-[(1 → 4)-GlcNS(6S)-(1 → 4)-IdoA(2S)-]3-(1 → 4)-GlcNS(6S) has been determined, where ∆UA(2S) is 2-O-sulfated ∆4,5-unsaturated uronic acid, GlcNS(6S) is 6-O-sulfated, N-sulfated β-d-glucosamine and IdoA(2S) is 2-O-sulfated α-l-iduronic acid. The spectrum was assigned, and the sites of N- and O-sulfation and the conformation of each uronic acid residue were established, with chemical shift data obtained from BASHD-TOCSY
spectra, while the sequence of the monosaccharide residues in the octasaccharide was determined from inter-residue NOEs in
BASHD-NOESY spectra. Acid dissociation constants were determined for each carboxylic acid group of the octasaccharide, as
well as for related tetra- and hexasaccharides, from chemical shift–pD titration curves. Chemical shift–pD titration curves
were obtained for each carboxylic acid group from sub-spectra taken from BASHD-TOCSY spectra that were measured as a function
of pD. The pK
As of the carboxylic acid groups of the ∆UA(2S) residues are less than those of the IdoA(2S) residues, and the pK
As of the carboxylic acid groups of the IdoA(2S) residues for a given oligosaccharide are similar in magnitude. Relative acidities
of the carboxylic acid groups of each oligosaccharide were calculated from chemical shift data by a pH-independent method. 相似文献
85.
In this paper, we give an affirmative answer to the problem posed by S. Lin (2002, 2007) in [7] and [8], and give another answer to the question posed by Y. Ikeda, C. Liu and Y. Tanaka (2002) in [5]. 相似文献
86.
Nguyen Le Hoang Anh Phan Quoc Khanh 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(6):2358-2379
We develop elements of calculus of variational sets for set-valued mappings, which were recently introduced in Khanh and Tuan (2008) [1] and [2] to replace generalized derivatives in establishing optimality conditions in nonsmooth optimization. Most of the usual calculus rules, from chain and sum rules to rules for unions, intersections, products and other operations on mappings, are established. Direct applications in stability and optimality conditions for various vector optimization problems are provided. 相似文献
87.
In this paper, we show that the ring of finite integral adeles, together with its Borel field and its normalized Haar measure,
is an appropriate probability space where limit-periodic arithmetical functions can be extended to random variables. The natural
extensions of additive and multiplicative functions are studied. Besides, the convergence of Fourier expansions of limit-periodic
functions is proved. 相似文献
88.
Partially consonant belief functions (pcb), studied by Walley, are the only class of Dempster-Shafer belief functions that are consistent with the likelihood principle of statistics. Structurally, the set of foci of a pcb is partitioned into non-overlapping groups and within each group, foci are nested. The pcb class includes both probability function and Zadeh’s possibility function as special cases. This paper studies decision making under uncertainty described by pcb. We prove a representation theorem for preference relation over pcb lotteries to satisfy an axiomatic system that is similar in spirit to von Neumann and Morgenstern’s axioms of the linear utility theory. The closed-form expression of utility of a pcb lottery is a combination of linear utility for probabilistic lottery and two-component (binary) utility for possibilistic lottery. In our model, the uncertainty information, risk attitude and ambiguity attitude are separately represented. A tractable technique to extract ambiguity attitude from a decision maker behavior is also discussed. 相似文献
89.
Jongsung Kim Jaechul Sung Ermaliza Razali Raphael C.-W. Phan Marc Joye 《Designs, Codes and Cryptography》2011,60(1):15-35
The theory of designing block ciphers is mature, having seen significant progress since the early 1990s for over two decades,
especially during the AES development effort. Nevertheless, interesting directions exist, in particular in the study of the
provable security of block ciphers along similar veins as public-key primitives, i.e. the notion of pseudorandomness (PRP)
and indistinguishability (IND). Furthermore, recent cryptanalytic progress has shown that block ciphers well designed against
known cryptanalysis techniques including related-key attacks (RKA) may turn out to be less secure against RKA than expected.
The notion of provable security of block ciphers against RKA was initiated by Bellare and Kohno, and subsequently treated
by Lucks. Concrete block cipher constructions were proposed therein with provable security guarantees. In this paper, we are
interested in the security notions for RKA-secure block ciphers. In the first part of the paper, we show that secure tweakable
permutation families in the sense of strong pseudorandom permutation (SPRP) can be transformed into secure permutation families
in the sense of SPRP against some classes of RKA (SPRP–RKA). This fact allows us to construct a secure SPRP–RKA cipher which
is faster than the Bellare–Kohno PRP–RKA cipher. We also show that function families of a certain form secure in the sense
of a pseudorandom function (PRF) can be transformed into secure permutation families in the sense of PRP against some classes
of RKA (PRP–RKA). We can exploit it to get various constructions secure against some classes of RKA from known MAC algorithms.
Furthermore, we discuss how the key recovery (KR) security of the Bellare–Kohno PRP–RKA, the Lucks PRP–RKA and our SPRP–RKA
ciphers relates to existing types of attacks on block ciphers like meet-in-the-middle and slide attacks. In the second part
of the paper, we define other security notions for RKA-secure block ciphers, namely in the sense of indistinguishability (IND) and non-malleability, and show the relations between these security notions. In particular, we show that secure tweakable permutation families
in the sense of IND (resp. non-malleability) can be transformed into RKA-secure permutation families in the sense of IND (resp.
non-malleability). 相似文献
90.
Nguyen HT Tran HQ Nguyen TT Chau VM Bui KA Pham QL Nguyen MC Kim YH 《Chemical & pharmaceutical bulletin》2011,59(11):1417-1420
Ten oleanane-type saponins (1-10), including three new compounds, namely bifinosides A-C (1-3), were isolated from the roots of Panax bipinnatifidus SEEM. Their structures were elucidated on the basis of chemical and spectroscopic methods. 相似文献