2006
Abstract. The asym. unit of the title compd., [Au(C10H8S2)(C18H15P)2], consists of two independent mols. The Au
coordination environment can be described as a highly distorted tetrahedral arrangement (S2AuP2), but is more accurately described as a flattened trigonal pyramid defined by three normal covalent bonds (SAuP2), with a second S atom more distantly bonded to the Au atom.
Abstract. Samples of flood water were collected from the Dillard University pond in New Orleans and analyzed. The following data were obtained: dissolved org. carbon: 19.5 mg/L (based on 57 mg/L total carbon and 37.5 mg/L inorg. carbon), pH 6.5, and cond. 16 mS. The logistics of urban flood water sampling, sampling site selection, and sample acquisition and workup are discussed.
Abstract. Recent expts. reveal unusual nucleation behavior for seemingly simple mixts. that cannot be described by the classical theory. Mol. simulations using a combination of aggregation-vol.-bias Monte Carlo, umbrella sampling, and histogram reweighting methods were carried out to study the nucleation events involved in the water/ethanol, water/n-nonane, and n-nonane/ethanol mixts. These simulations reproduced their different nonideal behaviors obsd. by the expts. Furthermore, the finding of their strikingly distinct mechanisms, as implied from the calcd. free-energy maps, challenges the current theor. description of this phenomenon.
Abstract. The flow of non-Newtonian fluids in packed beds and other porous media is important in several applications such as polymer processing, filtration, and enhanced oil recovery. Expressions for flowrate vs. pressure gradient are desirable for a-priori prediction and for substitution into continuum models. In this work, phys. representative network models are used to model the flow of shear-thinning fluids, including power-law and Ellis fluids. The networks are used to investigate the effects of fluid rheol. and bed morphol. on flow. A simple macroscopic model is developed for the flow of power-law and Ellis fluids in packed beds using results from the network model. The model has the same general functionality as those developed using the popular bundle-of-tubes approach. The const. b, which appears in these models, is often directly derived from the tortuosity and a simple representation of the porous media. It is shown here that this can lead to incorrect and ambiguous values of the const. Furthermore, the const. is a weak function of the shear-thinning index, indicating that no single bundle-of-tubes could ever properly model flow for a wide variety of shear-thinning fluids. The macroscopic model is compared to exptl. data for shear-thinning fluids available in the literature. The model fits the data well when b is treated as an exptl. parameter. The best-fit values of b vary, which is expected because even the const. C in the Blake-Kozeny equation varies depending on the source consulted. Addnl., phys. effects, such as adsorption and filtration, as well as rheol. effects such as viscoelasticity may affect the value of b. We believe that in the absence of these effects, b equals approx. 1.46 for packed beds of uniform spheres at relatively moderate values of the shear-thinning index (> 0.3
2005
Abstract. The unusual structure of poly(ethylene oxide) (PEO) and Laponite clay in transparent nanocomposite films was studied using scanning electron, at. force, and optical microscopy, and x-ray scattering. Each method is sensitive to different aspects of structural features and together they measure the resulting morphol. and shear-induced orientation. On nanometer length scales, clay platelets were found to orient in bundles while polymer crystallinity was suppressed. Microscopy led to the observation of unexpected and highly oriented multilayers on the micron length scale.
Electrodeposition was used to fabricate metallic CoNiCu and Cu nanotubes in polycarbonate membranes. The tubes were obtained from a low-efficiency CoNiCu electrolyte, crit. to the evolution of tube formation. Tube wall thickness was assessed and alloy tubes filled with Cu metal demonstrated. A high-efficiency electrolyte was used to show the importance of the side reaction on the nanotube formation. Nanowires were obtained in the high-efficiency electrolyte while nanotubes were generated from the low-efficiency electrolyte. Both gas evolution, resulting from electrodeposition, and partial pore coverage on the bottom of the membranes accounted for the tube formation.Abstract.
Abstract. A novel electron microscopy specimen protocol shows that the presumed phospholipid bilayer membrane ribbons that wind helically to form the cylinders known as "tubules" are actually flattened tubes. These flattened tubes are alternatively found with a helical twist about the tube's long axis or occasionally flat with no winding or twist. Flat, cylindrically wound and axially twisted segments are routinely found along a single tube's length, and at the helically wound and axially twisted segment junctions, the chiral sense of the structure often, but not always, changes chiral sense.
Abstract. The formation of β-Amyloid peptide (Aβ1-40) aggregates was monitored by dynamic light scattering. Various sizes of materials may be present throughout the aggregation process, but small scatterers are difficult to detect in the presence of large ones. Fluorescence photobleaching recovery studies on 5-carboxyfluorescein-labeled Aβ1-40 peptide solutions readily confirmed the presence of large and small species simultaneously. The effects of dye substitution on the aggregation behavior of Aβ1-40 peptide are subtle, but should not prevent further investigations by fluorescence photobleaching recovery or other fluorescence methods.
Surface-induced aggregation of beta amyloid peptide by co-substituted alkanethiol monolayers supported on gold. McMasters Mariah J; Hammer Robert P; McCarley Robin L Choppin Laboratories of Chemistry, Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, Louisiana 70803-1804, USA Langmuir : ACS journal of surfaces and colloids (2005), 21(10), 4464-70. Journal code: 9882736. ISSN:0743-7463. United States. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 16032861 AN 2005375190 In-process for MEDLINE.
Abstract. The primary pathological characteristic of Alzheimer's disease is the presence in the brain of self-assembled beta amyloid (Abeta) protein fibrils, consisting of 35-43 amino acid residues. The toxicity of the aggregated protein structures has previously been proposed to be related to the interaction of Abeta fibrils with neuronal membranes (phospholipid bilayers). Here, surfaces consisting of self-assembled alkanethiol monolayers with different end groups--supported on Au--are used to test the effect of surface chemistry on the structure and morphology of aggregates formed from an active fragment (Abeta10-35) of the Abeta peptide. The influence of monolayer nature (end group) on the aggregation of Abeta10-35 was examined using reflection-absorption infrared spectroscopy (RAIRS) and scanning force microscopy (SFM). Evaluation of the SFM and RAIRS data reveals the presence of Abeta10-35 protein on the various monolayer surfaces, with the surface protein possessing predominantly beta-sheet and random-coil conformations. Time-dependent studies of the extent of Abeta10-35 aggregation and deposition on the various surfaces and the effect of the monolayers on seeding of Abeta10-35 aggregates in solution are also discussed.
Investigation into the kinetics of desorption of hydrophobic organic compounds from suspended geosorbents: A literature review. Birdwell, Justin; Thibodeaux, Louis J. Gordon A. and Mary Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA, USA. Preprints of Extended Abstracts presented at the ACS National Meeting, American Chemical Society, Division of Environmental Chemistry (2004), 44(2), 1227-1231. Publisher: American Chemical Society, Division of Environmental Chemistry, CODEN: PEACF2 ISSN: 1524-6434. Journal; General Review; Computer Optical Disk written in English. CAN 141:247945 AN 2004:613509 CAPLUS
Abstract. A review. The effect of various thermodn. and transport properties of hydrophobic org. compds. (HOCs) on desorption kinetics was examd. by collecting the values of these rate consts. from the literature and compared to contaminant and sediment properties. The hydrophobicity and low volatility of HOCs are the factors leading to their presence in soils and sediments. The release rates of HOCs are governed by some complex relation of the basic system properties or that the process could be independent of these properties. It could also be that the rate consts. in the two-mode desorption empirical algorithm are merely fitting parameters with no phys. significance and the lack of dependence on soly. is an artifact of the model.
2004
Modeling the steady flow of yield-stress fluids in packed beds. Balhoff, Matthew T.; Thompson, Karsten E. Gordon A. and Mary Cain Dept. of Chemical Engineering, Louisiana State University, Baton Rouge, LA, USA. AIChE Journal (2004), 50(12), 3034-3048. CODEN: AICEAC ISSN: 0001-1541. Journal written in English. CAN 142:25214 AN 2004:1062512 CAPLUS (Copyright 2005 ACS on SciFinder (R))
Abstract. Network modeling has been performed to obtain quant. and predictive results of the flow of yield-stress fluids in packed beds. Phys. representative networks were used as the basis for the modeling, which have a one-to-one correspondence to computer-generated packed beds of spheres. The networks are able to account for the interconnectivity, heterogeneity, and converging/diverging geometry that are inherent in porous media. The approach can be used to model a wide range of non-Newtonian fluids, but the emphasis is for yield-stress fluids that can be represented using a Bingham model. For these fluids, a threshold pressure gradient is required to initiate flow, and flow at low pressure gradients is characterized by crit. percolation behavior. Quant. results of superficial velocity vs. pressure gradient are presented, and are compared to traditional bundle-of-tubes models, as well as limited exptl. data available in the literature. Important differences are obsd. between the network model and the constitutive models. These are attributed mainly to heterogeneity and converging/diverging geometry, which are not accounted for in the semiempirical models. Comparison to exptl. data is good for certain fluids. In other cases, the modeling suggests that effects other than fluid rheol. may also have affected flow, such as adsorption or filtration.
Structural Changes and Aggregation of Human Influenza Virus. Campbell, Jason N.; Epand, Richard M.; Russo, Paul S. Department of Chemistry and Macromolecular Studies Group, Louisiana State University, Baton Rouge, LA, USA. Biomacromolecules (2004), 5(5), 1728-1735. CODEN: BOMAF6 ISSN: 1525-7797. Journal written in English. CAN 141:239732 AN 2004:559146 CAPLUS (Copyright 2005 ACS on SciFinder (R))
Abstract. The pH-induced change in the structure and aggregation state of the PR-8 and X-31 strains of intact human influenza virus has been studied in vitro. Reducing the pH from 7.4 to 5.0 produces a large increase in the intensity of light scattered to low angles. A modest increase in the polydispersity parameter from cumulants fits to the dynamic light scattering correlograms accompanies the increase, as does a change in how that parameter varies with scattering angle. These trends imply that the virus particles are not uniform, even at pH 7.4, and tend to aggregate as pH is reduced. The scattering profiles (angular dependence of intensity) never match those of isolated, spherical particles of uniform size, but the deviations from that simple model remain modest at pH 7.4. At pH 5.0, scattering profiles calcd. for aggregates of uniformly sized spheres come much closer to matching the exptl. data than those computed for isolated particles. Although these observations indicate that acid-induced aggregation develops over a period of minutes to hours after acidification, a nearly instantaneous increase in hydrodynamic size is the first response of intact virus particles to lower pH.
Evidence for shape selectivity in non-covalently imprinted polymers. Spivak, David A.; Simon, Ryan; Campbell, Jason. Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA. Analytica Chimica Acta (2004), 504(1), 23-30. CODEN: ACACAM ISSN: 0003-2670. Journal written in English. CAN 140:296543 AN 2004:74953 CAPLUS (Copyright 2005 ACS on SciFinder (R))
Abstract. The existence of shape selectivity in noncovalent molecularly imprinted polymers (MIPs) was proven using mol. probes. Twelve secondary amines with different sized side chains were imprinted, and enantioselectivity evaluated by HPLC for each amine on each imprinted polymer. Trends in the quant. structure-binding relations (QSBR) revealed two major contributions of cavity structure on selectivity afforded by molecularly imprinted polymers. First, sterics play a dominant role in cases where a mols. structure is too big too fit into an imprinted site formed from a smaller template mol.; e.g. on MIPs made with small templates, large analytes give sepn. factors (a) close to 1.0 (no selectivity), while small analytes give a values of 1.4. Second, mol. structures that are equal to or smaller than those of the template mol. are selected by maximizing Van der Waals interactions within the MIP binding site. Thus, MIPs made with large analytes give a values up to 2.5, while small analytes on the same MIPs give a values closer to 1.1. Template structure also has an effect on MIP enantioselectivity; e.g. branched structures exhibit a 1.7-fold improvement in sepn. factors (a) by MIPs made for iso-Pr vs. Pr derivs., and cyclohexyl vs. hexyl derivs. Full details of these trends are provided in the text.
Rotational and Translational Diffusion of Tobacco Mosaic Virus in Extended and Globular Polymer Solutions. Cush, Randy; Dorman, Derek; Russo, Paul S. Department of Chemistry and Macromolecular Studies Group, Louisiana State University, Baton Rouge, LA, USA. Macromolecules (2004), 37(25), 9577-9584. CODEN: MAMOBX ISSN: 0024-9297. Journal written in English. AN 2004:961701 CAPLUS (Copyright 2005 ACS on SciFinder (R))
Abstract. Depolarized dynamic light scattering is used to measure the translational and rotational diffusion of a rodlike probe, tobacco mosaic virus, in matrix solns. of dextran, an extended polymer with some branching, and globular Ficoll. Translation and rotation both decline almost exponentially as the concn. of either matrix rises. The ratio of rotational to translational diffusion is similar in dextran or Ficoll solns. and close to the values expected from continuum theories of the friction of rodlike particles. Reinforcing a continuum picture in which hydrodynamic effects surpass any due to topol. constraints, the declines in rotational and translational motion are almost inversely proportional to the soln. viscosity. Only modest and gradual deviations from Stokes-Einstein behavior are obsd., even at high matrix concns. This stands in stark contrast to an earlier study by this group [Macromols. 1997, 30, 4920-4926]. The difference may be traced to the subtle effects of optical rotation (dextran and Ficoll are chiral) on instrument alignment, coupled to the weak depolarization of the strongly scattering tobacco mosaic virus and the very slow rotations encountered at high matrix content. In optically inactive solns., and even in optically active ones studied with the correct and tedious alignment, a particle the shape and size of tobacco mosaic virus can serve as an effective microrheol. probe. Confirming this conclusion, the apparent microviscosity obtained by inverting rotational or translational diffusion coeffs. reflected the mol. wt. trend, at a particular concn., of shear viscosity measured in a cone and plate device.
Extreme free energy of stabilization of Taq DNA polymerase. Schoeffler Allyn J; Joubert Allison M; Peng Fenggang; Khan Farheen; Liu Chin-Chi; LiCata Vince J Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA Proteins (2004 Mar 1), 54(4), 616-21. Journal code: 8700181. ISSN:1097-0134. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14997557 AN 2004107031 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))
Abstract. We have examined the chemical denaturations of the Klentaq and Klenow large-fragment domains of the Type 1 DNA polymerases from Thermus aquaticus (Klentaq) and Escherichia coli (Klenow) under identical solution conditions in order to directly compare the stabilization energetics of the two proteins. The high temperature stability of Taq DNA polymerase is common knowledge, and is the basis of its use in the polymerase chain reaction. This study, however, is aimed at understanding the thermodynamic basis for this high-temperature stability. Chemical denaturations with guanidine hydrochloride report a folding free energy (DeltaG) for Klentaq that is over 20 kcal/mol more favorable than that for Klenow under the conditions examined. This difference between the stabilization free energies of a homologous mesophilic-thermophilic protein pair is significantly larger than generally observed. This is due in part to the fact that the stabilization free energy for Klentaq polymerase, at 27.5 kcal/mol, is one of the largest ever determined for a monomeric protein. Large differences in the chemical midpoints of the unfolding (Cm) and the dependences of the unfolding free energy on denaturant concentration in the transition region (m-value) between the two proteins are also observed. Measurements of the sedimentation coefficients of the two proteins in the native and denatured states report that both proteins approximately double in hydrodynamic size upon denaturation, but that Klentaq expands somewhat more than Klenow. Copyright 2004 Wiley-Liss, Inc.
Orientation and relaxation of polymer-clay solutions studied by rheology and small-angle neutron scattering. Malwitz, Matthew M.; Butler, Paul D.; Porcar, Lionel; Angelette, Drew P.; Schmidt, Gudrun. Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA. Journal of Polymer Science, Part B: Polymer Physics (2004), 42(17), 3102-3112. CODEN: JPBPEM ISSN: 0887-6266. Journal written in English. CAN 141:366866 AN 2004:717379 CAPLUS (Copyright 2005 ACS on SciFinder (R))
Abstract. The influence of shear on viscoelastic solns. of poly(ethylene oxide) (PEO) and clay [montmorillonite, i.e., Cloisite NA+ (CNA)] was investigated with rheol. and small-angle neutron scattering (SANS). The steady-state viscosity and SANS were used to measure the shear-induced orientation and relaxation of the polymer and clay platelets. Anisotropic scattering patterns developed at much lower shear rates than in pure clay solns. The scattering anisotropy satd. at low shear rates, and the CNA clay platelets aligned with the flow, with the surface normal parallel to the gradient direction. The cessation of shear led to partial and slow randomization of the CNA platelets, whereas extremely fast relaxation was obsd. for laponite (LRD) platelets. These PEO-CNA networklike solns. were compared with previously reported PEO-LRD networks, and the differences and similarities, with respect to the shear orientation, relaxation, and polymer-clay interactions, were examd.
Layered structures of shear-oriented and multilayered PEO/silicate nanocomposite films. Malwitz, Matthew M.; Dundigalla, Avinash; Ferreiro, Vincent; Butler, Paul D.; Henk, Margaret C.; Schmidt, Gudrun. Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA. Physical Chemistry Chemical Physics (2004), 6(11), 2977-2982. CODEN: PPCPFQ ISSN: 1463-9076. Journal written in English. CAN 141:146117 AN 2004:422831 CAPLUS (Copyright 2005 ACS on SciFinder (R))
Abstract. The structure and orientation of polymer and clay platelets in multilayered, micrometer-thick nanocomposite films was investigated by means of SEM (SEM), at. force microscopy (AFM), optical microscopy and small-angle neutron scattering (SANS). Microscopic and scattering methods complementarily measured the morphol. and shear-induced orientation of polymer and platelets in films when spread layer by layer from a network-like polymer clay soln. During the drying process, the polymer clay network collapsed and clay platelets oriented inside the network with the clay surface normal perpendicular to the spread direction (x-z plane). On nanometer length scales, SANS and AFM yielded structure and orientation of platelets and polymer in and perpendicular to the spread direction of the film. SEM investigations led to the observation of unexpected morphol. on the micron length scale. SEM did not detect boundaries between single spread, micron-thick film layers but, surprisingly, showed a highly ordered and layered structure of the film. Polarized light microscopy showed differences in birefringence in each plane.
2003 (updated Jan. 2003)
Salt Modulates the Stability and Lipid Binding Affinity of the Adipocyte Lipid-binding Proteins. Schoeffler, Allyn J.; Ruiz, Carmen R.; Joubert, Allison M.; Yang, Xuemei; LiCata, Vince J. Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA. Journal of Biological Chemistry (2003), 278(35), 33268-33275. CODEN: JBCHA3 ISSN: 0021-9258. Journal written in English. CAN 139:287875 AN 2003:662634 CAPLUS (Copyright 2004 ACS on SciFinder (R))
Abstract. Adipocyte lipid-binding protein (ALBP or aP2) is an intracellular fatty acid-binding protein that is found in adipocytes and macrophages and binds a large variety of intracellular lipids with high affinity. Although intracellular lipids are frequently charged, biochem. studies of lipid-binding proteins and their interactions often focus most heavily on the hydrophobic aspects of these proteins and their interactions. In this study, we have characterized the effects of KCl on the stability and lipid binding properties of ALBP. We find that added salt dramatically stabilizes ALBP, increasing its DG of unfolding by 3-5 kcal/mol. At 37 °C salt can more than double the stability of the protein. At the same time, salt inhibits the binding of the fluorescent lipid 1-anilinonaphthalene-8-sulfonate (ANS) to the protein and induces direct displacement of the lipid from the protein. Thermodn. linkage anal. of the salt inhibition of ANS binding shows a nearly 1:1 reciprocal linkage: i.e. one ion is released from ALBP when ANS binds, and vice versa. Kinetic expts. show that salt reduces the rate of assocn. between ANS and ALBP while simultaneously increasing the dissocn. rate of ANS from the protein. We depict and discuss the thermodn. linkages among stability, lipid binding, and salt effects for ALBP, including the use of these linkages to calc. the affinity of ANS for the denatured state of ALBP and its dependence on salt concn. We also discuss the potential mol. origins and potential intracellular consequences of the demonstrated salt linkages to stability and lipid binding in ALBP.
Global conformations, hydrodynamics, and x-ray scattering properties of Taq and Escherichia coli DNA polymerases in solution. Joubert, Allison M.; Byrd, Angela S.; LiCata, Vince J. Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA. Journal of Biological Chemistry (2003), 278(28), 25341-25347. CODEN: JBCHA3 ISSN: 0021-9258. Journal written in English. CAN 139:226421 AN 2003:524562 CAPLUS (Copyright 2004 ACS on SciFinder (R))
Abstract. E. coli polymerase 1 (Pol 1) and Thermus aquaticus Taq polymerase are homologous type I DNA polymerases, each comprised of a polymerase domain, a proofreading domain (inactive in Taq), and a 5' nuclease domain. "Klenow" and "Klentaq" are the large fragments of Pol 1 and Taq, resp., and are functional polymerases lacking the 5' nuclease domain. In the available crystal structures of full-length Taq, the 5' nuclease domain is positioned in 2 different orientations: in one structure, it is extended out into soln., whereas in the other, it is folded up against the polymerase domain in a more compact structure. Here, anal. ultracentrifugation expts. report s20,w values of 5.05 for Taq, 4.1 for Klentaq, 5.3 for E. coli Pol 1, and 4.6 for Klenow. The measured partial sp. vols. were all quite similar, indicating no significant differences in packing d. between the mesophilic and thermophilic proteins. Small angle x-ray scattering studies report radius of gyration values of 38.3 .ANG. for Taq, 30.7 .ANG. for Klentaq, and 30.5 .ANG. for Klenow. The hydrodynamic and x-ray scattering properties of the polymerases were also calcd. directly from the different crystal structures using computer programs HYDROPRO and CRYSOL, resp. The combined exptl. and computational characterizations indicated that the full-length polymerases in soln. were in a conformation where the 5' nuclease domain was extended into soln. Further, the radius of gyration, and hence the global conformation of Taq polymerase, was not altered by the binding of either matched primer template DNA or ddATP.
Factors Affecting the Size of Aqueous Poly(vinylphenol-co-potassium styrenesulfonate)/Poly(ethylene oxide) Complexes. Cong, Rongjuan; Pelton, Robert; Russo, Paul; Doucet, Garrett. Department of Chemical Engineering, McMaster University, Hamilton, ON, Can. Macromolecules (2003), 36(1), 204-209. CODEN: MAMOBX ISSN: 0024-9297. Journal written in English. CAN 138:154263 AN 2002:943033 CAPLUS (Copyright 2004 ACS on SciFinder (R))
Abstract. The diffusion properties of complexes formed between poly(ethylene oxide) (PEO) and poly(vinylphenol-co-styrenesulfonate) (PKS) in aq. medium were investigated by diffusion ordered NMR, fluorescence photobleaching recovery, and viscosity measurements. All 3 techniques showed that PEO/PKS complexes range from single PEO coils with bound PKS mols. to large complex species contg. many PEO chains. For a given PKS structure, there are 2 important transitional PEO mol. wts. The lowest one, .apprx.8000 Da, corresponds to the onset of PEO/PKS complex formation. The second transitional PEO mol. wt. is between 105 and 106 Da and corresponds to the onset of multi-PEO chain complex species which are important for flocculation. PKS functions as a phys. crosslinking agent for PEO. If there is too little PKS, multiple PEO chains are not bound together. Similarly, high concns. of PKS give small complexes because there are few opportunities for connecting multiple PEO chains together, since all the PEO chains are satd. with bound PKS.
Properties of polymer-nanoparticle composites. Schmidt, Gudrun; Malwitz, Matthew M.. Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA. Current Opinion in Colloid & Interface Science (2003), 8(1), 103-108. CODEN: COCSFL ISSN: 1359-0294. Journal; General Review written in English. CAN 139:324072 AN 2003:446060 CAPLUS (Copyright 2004 ACS on SciFinder (R))
Abstract. A review of properties of polymer-nanoparticle composites in bulk and in soln. is presented with stress on work performed during the last 3 yr. The review is particularly focused on org.-inorg. materials such as polymer-nanospheres, tubes, rods, fibers, and nanoplatelets. Fundamental studies on flow-induced structures in polymer-particle composites are emphasized. This relatively new area demands sophisticated expts. to augment pragmatic knowledge necessary to support theor. descriptions of composite structures and properties. The complexity of this area guarantees that this will remain an active field for some time to come.
2001
Systematic study of steric and spatial contributions to molecular recognition by non-covalent imprinted polymers. Spivak, David A.; Campbell, Jason. Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA. Analyst (Cambridge, United Kingdom) (2001), 126(6), 793-797. CODEN: ANALAO ISSN: 0003-2654. Journal written in English. CAN 135:211926 AN 2001:399463 CAPLUS (Copyright 2004 ACS on SciFinder (R))
Abstract. Although mol. imprinting is a widely accepted method for producing template specific polymers, the general rules for prediction and control of the binding and catalytic properties of these materials are still not fully understood. One reason for this is the problematic structural anal. of the active sites in the polymers, which are not amenable to X-ray crystallog. or microscopic techniques due to their amorphous and heterogeneous nature. Therefore, mol. probes have been the most informative agents for the anal. of the structure of active sites. This paper focuses on the steric and geometrical aspects of shape recognition in non-covalent imprinted polymers, with particular effort to minimize other factors contributing to mol. recognition by the polymers. Chiral amine compds. with systematic changes in spatial, distal and conformational components of sterically controlled mol. recognition were investigated for use as non-covalent imprinted polymers. Chromatog. studies revealed that steric and spatial interactions influence the selectivity properties of imprinted polymers in a predictable fashion.