Experimental studies on affinity chromatography in an electric field.

A multicompartment electrolyzer, which has been used for preparative electrophoresis [Z. Liu, Z. Huang, J.-Y. Cong, et al., Sep. Sci. Technol. 31 (1996) 427], is applied for carrying out affinity chromatography in an alternating electric field. The effect of electric field strength on the adsorption and desorption characteristics is experimentally examined with human serum albumin and Blue Sepharose Fast Flow as a model system. It is shown that the existence of an electric field leads to a significant change in the adsorption capacity of the blue dye, which may be used for establishing a preferential adsorption to achieve a high resolution. The adsorption speed increases slightly with respect to the increase of electric field strength, while adsorption capacity in the presence of an electric field is independent of the electric field strength. Different elution behavior is observed as function of adsorption condition and a high recovery of the adsorbed protein is obtained when the adsorption is carried out in the presence of an electric field.     

Multistimuli‐responsive hyperbranched poly(ether amine)s

Multistimuli‐responsive hyperbranched poly(ether amine)s (hPEAs) were successfully synthesized through nucleophilic addition/ring‐opening reaction of commercial diglycidyl ether and amine via one‐pot synthesis. In aqueous solution, these hPEAs exhibited very sharp response to temperature, pH, and ionic strength, with well‐tunable cloud point (CP). Through changing the poly(ethylene oxide) (PEO) chain content of hPEAs, pH, and ionic strength, the CP could be adjustable from 35 to 100 °C, and increased with the increasing of PEO content, the decreasing of pH and ionic strength. The CP of hPEAs aqueous solution presents a linear relationship to the PEO content in pH range from 6.6 to 8.0. Dynamic light scattering (DLS) investigation indicated that these hPEAs dispersed in aqueous solution to form the stable nanomicelles, whose aggregation can be controlled by temperature, pH, and ionic strength. Moreover, the obtained hPEAs contain reactive amino groups in periphery and hydroxyl groups inside, which can be further functionalized. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4252–4261, 2010     

Singularly Perturbed Switching Diffusions: Rapid Switchings and Fast Diffusions

Motivated by many problems in optimization and control, this paper is concerned with singularly perturbed systems involving both diffusions and pure jump processes. Two models are treated. In the first model, the jump process changes very rapidly by comparison with the diffusion processes. In the second model, the diffusions change rapidly in comparison with the jump process. Asymptotic expansions are developed for the transition density vectors via a constructive method; justification of the asymptotic expansions and analysis of the remainders are provided.     

Collectivity of plasmon excitations in small sodium clusters with planar structure

The collectivity of the electronic motion in small sodium clusters with planar structure is studied by the time-dependent density functional theory (TDDFT). The formation and development of collective resonances in the absorption spectra were obtained as the function of the size and shape of the plane. We find the symmetry plays an important role in the collective excitation. Resonance peaks increase with the reduction of the symmetries and, on the contrary, resonance peaks decrease with the increase of the symmetries. In the planar cluster, there are two main excitation modes: the higher-energy mode and the competitive mode, which is due to the coupling and competition of the quasi-lower-energy effect and the quasi-higher-energy effect. With the increase of the interatomic distance, peaks of the absorption spectra are all red-shifted and the evolutionary trend is also discussed.     

Stochastic Generalized Method of Moments

The generalized method of moments (GMM) is a very popular estimation and inference procedure based on moment conditions. When likelihood-based methods are difficult to implement, one can often derive various moment conditions and construct the GMM objective function. However, minimization of the objective function in the GMM may be challenging, especially over a large parameter space. Due to the special structure of the GMM, we propose a new sampling-based algorithm, the stochastic GMM sampler, which replaces the multivariate minimization problem by a series of conditional sampling procedures. We develop the theoretical properties of the proposed iterative Monte Carlo method, and demonstrate its superior performance over other GMM estimation procedures in simulation studies. As an illustration, we apply the stochastic GMM sampler to a Medfly life longevity study. Supplemental materials for the article are available online.     

The Syntheses of Triazinone and Pyrimidinone Biphenyltetrazoles as Angiotensin II Receptor Antagonists

A series of biphenylyltetrazole substituted triazinones and structure-related pyrimidinones are systhesized, and their binding affinities for angiotensin II receptor are reported.     

VAPOR PRESSURES OF FRAGRANCE COMPOUNDS DURING CONTROLLED EVAPORATION

The content of each of the three components in the vapor phase from a phenethyl alcohol, - limonene - decane solution was determined from the composition of the condensed phase during controlled evaporation with turbulent gas flow, with complete removal of the vapor phase once per second and the values compared to those from vapor pressures determined at equilibrium.

The results showed the vapor composition during rapid removal of the vapor to be surprisingly similar to the equilibrium values.     

Supramolecular nanostructures from self‐assembly of T‐shaped rod building block oligomers

T‐shaped coil–rod–coil oligomers, consisting of a dibenzo[a,c]phenazine unit and phenyl groups linked together with acetylenyl bonds at the 2,7‐position of dibenzo[a,c]phenazine as a rigid segment have been synthesized. The coil segments of these new molecules composed of poly(ethylene oxide) (PEO)–poly(propylene oxide) (PPO) incorporating lateral methyl groups between the rod and coil segment and two flexible alkyl groups connecting with the rigid segment at the 4,6‐position of dibenzo[a,c]phenazine, respectively. The experimental results reveal that the length of the flexible PEO coil chain influence construction of various supra‐nanostructures from lamellar structure to rectangular columnar structure. It is also shown that introduction of different length of alkyl side chain groups in the backbone of the T‐shaped molecules affect the self‐organization behavior to form hexagonal perforate layer or oblique columnar structures. In addition, lateral methyl groups attached to the surface of rod and coil segments, dramatically influence the self‐assembling behavior in the crystalline phase. T‐shaped molecules containing a lateral methyl group at the surface of rod and PEO coil segments, self‐assemble into 3D body‐centered tetragonal structures in the crystalline phase, while molecules without a lateral methyl group based on PEO coil chain self‐organize into 2D oblique columnar crystalline structures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5021–5028