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A study is conducted which demonstrates that the films absorb a substantial amount of solvent (CHCL3) to which they are exposed. Organic solutes have high permeability in the films compared to the penetrants of similar size in gas permeation, as a result of this.

A black box approach is used to identify the core regions of the two subunits, PecE and PecF, and several critical amino acid residues within that are responsible for the complete reaction sequence by which phycocyanobilin (PCB) is attached to apoprotein of alpha-phycoerythrobilin (PecA) and isomerized to phycoviolobilin (PVB). The findings indicate that PecF alone is capable of the complete reaction sequence, although with low yield.

Chromophore attachment to phytochrome AlphA of the cyanobacterium Anabaena sp.PCC 7120, as well as to N-and C-terminally truncated AphA is reported. Several methods of phytochrome reconstitution are addressed, including the autocatalytic assembly of apo phytochrome with free phycocyanobilin (PCB) and the chromophore transfer from phycocyanin (CPC) to apo phytochrome autocatalytically and in the presence of PCB:CpcA lyase (CpcE/F).

Research has been conducted on the phycocyanobilin (PCB). The purification of the overexpressed lyase subunits and their interactions with PCB, the detail of the products of the PCB addition/isomerization and the pigment specificity of the phycoerythrocyanin-Cys-alpha84 PCB lyase/isomerase have been investigated and discussed.

It was shown that the acylation of the 20-OH group of camptothecin (CPT) with PEG yielded water soluble derivatives in which the lactone structure (E-ring) remained stable under physiological conditions (PH7.4, 37 degrees C). UV and NMR spectrophotometry and HPCL analysis were used for the experiment.

The homochiral inorganic-organic hybrid compound (H(sub 3)NHPA)-(SnCl(sub 3))(sub 2)(H(sub 2)O)(sub 3) has a TGS (triglycine sulfate)-like structure. Preliminary investigations suggest a possible ferroelectric behavior with a saturation spontaneous polarization, which is slightly greater than that of TGS.

Cylindrical micelles are produced by extruding spherical micelles through nanoscale pores. The cylindrical micelles and their transformation back into the spherical micelles are characterized and the extrusion process is shown to be continuous and simple.

A combination of spectral analysis and X-ray crystallographic analysis was performed to establish the molecular structure of marine metabolite carbon skeleton, aberrarone as a natural product from the Caribbean sea whip, Pseudopterogorgia elisabethae. Aberrarone showed in vitro antimalarial activity against a chloroquine-resistant strain of the protozoan parasite Plasmodium falciparum.

The addition of thiol and imidazole to phycocyanobilin is used for proposing a generalized lyase reaction mechanism. The adducts possess isomerized phycocyanobilin that are transferred by the lyase to apoproteins by either back-isomerization, generating phycocyanobilin-containing proteins, or direct transfer, generating phycoviolobilin-containing proteins.

The study results of an extensive human thioesterase superfamily member 2 (hTHEM2) substrate screens, the structural characterization of hTHEM2 complexed with the inert substrate analogue undecan-2-one-CoA and the kinetic analysis of active site mutants is presented. The results obtained for the structure-function analysis of hTHEM2 offer insight into the physiological role of hTHEM2, which involves catalysis of the hydrolysis of cytosolic medium-to-long-chain acyl-CoA thioesters.

A study was conducted to examine the biochemical and biological function of the hot dog fold thioesterase YciA (EcYciA) from Escherichia coli and its close sequence homologue HI0827 from Haemophilus influenzae (HiYciA). The results provide insight into significant role of YciA for efficient CoA-regulated hydrolysis of cellular acyl-CoA thioesters in a wide range of bacteria.

X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) are used to investigate the Co chemisorption on the metallic molybdenum nanoparticles supported on the thin alumina film. The formation of the [Mo.sub.x][(CO).sub.y] species has implied that the property of the metallic molybdenum nanoparticles on the thin alumina film is much different from that of the bulk molybdenum, thereby implying a significant nanometer size effect.

The reaction of Cu(I) with 2-pyridylacrylic acid (2-HPYA) is studied, which affords an unusual mixed-valence Cu(I)-Cu(III) 3-dimensional (3-D) framework. The results provide encouragement that the use of ligands combining carboxylate and pyridyl groups as building blocks in coordination polymers may provide access to a novel range of extended structures.

Three novel highly stable 3-D copper(I)- olefin dimers were yielded by the UV irradiation of 2-, 3-, and 4-pyridylacrylic acid with CuICl at 230 nm in 4 N HCl for 1week and subsequent hydrothermal reactions. Copper(I)-olefin complexes are used extensively in a variety of stress responses and developmental processes.

Research has been conducted on (S)-3-cyanophenylalanine. The authors describe the reactions of this compound with NaN (sub)3 in the presence of Lewis acids and H (sub) O, and report that these reactions produce 3D homochiral networks.

Research has been conducted on Cu(I)(CH (sub)3 CN) (sub)4 BF (sub)4. The authors describe the reaction of this compound with 4-pyridylacrylic acid whic leads to 8-fold diamondoid-like coordination polymer network.

Research has been conducted on reactions of 2-, 3- and 4-cyanopyridine with NaN (sub)3. Results demonstrate that these reactions carried out in the presence of Lewis acid and H (sub)2 O lead to discrete monomer and 2D layered network, and that their nature and structure help to understand the Sharpless reaction of 5-substituted 1H-tetrazole.

A study is conducted to investigate poly(2,2-bis(trifluoro-methyl)-4,5-difluoro-1,3-doxide-co-tetrafluoroethylene (Teflon AF), a stable fluorous polymer, as a transport/extraction medium for solutes. Teflon AF contains 13 mol percent tetrafluoroethylene and is moderately soluble in some fluorinated solvents at room temperature, which allows thin and dimensionally stable films to be cast easily.

Monodispersed chitosan/silica core-shell microspheres-supported Pd catalysts were prepared by a simple and affordable microfluidic device. Merely 5 mg of supported Pd catalyst (1 wt %) showed superior capability in Sonogashira coupling reactions between various aryl iodides and terminal alkynes in a mild environment (ligand-free, copper-free, amine-free, water-ethanol as solvent at 65 °C) even after eight cycles of use. These novel porous composite microspheres provide a new carrier to reduce the loading, enhance the activity, and increase the stability of noble metal catalyst. [ABSTRACT FROM AUTHOR]

[RuCl2(p-cymene)]2 in a mixture of poly(ethylene glycol) (PEG-400) and water is shown to be an extremely efficient catalyst for the cross-dehydrogenative C-H bond alkenylation reaction between benzoic acids and alkenes. The reaction could be conducted at 80 °C using Cu(OAc)2⋅H2O as oxidant, yielding a variety of phthalide derivatives in good to excellent yields. More importantly, both [RuCl2(p-cymene)]2 and Cu(OAc)2 in the PEG-400/H2O system could be easily recycled and reused six times without any loss of catalytic activity. [ABSTRACT FROM AUTHOR]

High concentrations of copper chloride solutions (in the molar range) are used in several industrial applications. In this work, we investigated the species distribution of copper chloride complexes and how to measure the copper concentration precisely at high concentrations using electrochemical methods, by including migrational effects. The latter, in fact, can be useful in determining the nature of the species in solution undergoing electron transfer at the electrode. The study indicates that the main species of Cu(II) complexes in high chloride concentration is CuCl42- and the main species of Cu(I) complexes are CuCl2- and CuCl32-. However insoluble CuCl is an intermediate in the process and can deactivate the electrode surface. This can be ameliorated by increasing the temperature or Cl- concentration. Under these conditions, voltammetry with an ultramicroelectrode (UME) can measure copper concentration with good precision even at 1 M Cu(II) concentrations in a few molar chloride. The main charge of the species can be determined by fitting to a migration model. [ABSTRACT FROM AUTHOR]

Thin films of poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (C14–PBTTT) exhibit a monolayer-terraced morphology that indicates a pronounced lamellar order with π-stacks of extended polymer chains. Previously this remarkable state of order was thought to be promoted by the interdigitation of alkyl side chains between the lamellae during cooling from the liquid-crystalline (LC) phase. Here we establish that the key to this ordering in fact is the formation of unentangled π-stacks of extended polymer chains in dilute solutions of chlorobenzene (CB) or 1,2-dichlorobenzene (o-DCB), which though routinely used as the “best” solvents are in fact borderline solvents. Film formation causes these π-stacks to deposit substantially oriented in the film plane, while the subsequent anneal and cool from LC phase accentuates this incipient order to develop the monolayer-terraced morphology. This mechanism is supported by the following lines of evidence. (i) Hydrodynamic and viscometry measurements respectively of the Kuhn segment length and Mark–Houwink–Sakurada exponent of PBTTT reveal that CB is a near-Θ solvent, and PBTTT is significantly stiffer than regioregular polythiophene. (ii) Solution-state UV–vis spectroscopy reveals an early coil → rod transition in highly dilute solutions, which gives rise to unentangled π-stacks. (iii) Solid-state UV–vis spectroscopy, atomic force microscopy and variable-angle spectroscopic ellipsometry together reveal the as-deposited π-stacks are already substantially oriented in the film plane. We further demonstrate that this monolayer-terraced morphology can also be induced in regioregular poly(3-hexylthiophene) films using a borderline solvent mixture of chlorobenzene and mesitylene, and in very dilute CB where the incipient π-stacks do not entangle. Therefore, this dilute π-stacking mechanism is general. Processing with a borderline solvent or solvent additive thus provides a general route to obtain superior supramolecular order in π-stackable conjugated polymers. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of organic–inorganic hybrid materials that selectively capture sugars from model biomass hydrolysis mixtures are reported. 3-Aminophenylboronic acid (PBA) groups that can reversibly form cyclic esters with 1,2-diols, and 1,3-diols including sugars are attached to mesoporous SBA-15 via different synthetic protocols. In the first route, a coupling agent is used to link PBA and SBA-15, while in the second route poly(acrylic acid) brushes are first grafted from the surface of SBA-15 by surface-initiated atom transfer radical polymerization and PBA is then immobilized. The changes in pore structure, porosity, and pore size due to the loading of organic content are measured by powder X-ray diffraction and nitrogen porosimetry. The increase in organic content after each synthesis step is monitored by thermal gravimetric analysis. Fourier transform infrared spectroscopy and elemental analysis are used to characterize the chemical compositions of the hybrid materials synthesized. d-(+)-Glucose and d-(+)-xylose, being the most commonly present sugars in biomass, are chosen to evaluate the sugar adsorption capacity of the hybrid materials. It is found that the sugar adsorption capacity is determined by the loading of boronic acid groups on the hybrid materials, and the hybrid material synthesized via route two is much better than that through route one for sugar adsorption. Mathematical modeling of the adsorption data indicates that the Langmuir model best describes the sugar adsorption behavior of the hybrid material synthesized through route one, while the Freundlich model fits the data most satisfactorily for the hybrid material prepared via route two. The adsorption kinetics, reusability, and selectivity toward some typical chemicals in cellulose acidic hydrolysis mixtures are also investigated. [ABSTRACT FROM AUTHOR]

Inspired by the superhydrophobic effect displayed in nature, we set out to mimic the interplay between the chemistry and physics in the lotus leaf to see if the same design principle can be applied to control wetting and adhesion between toners and inks on various printing surfaces. Since toners and inks are organic materials, superoleophobicity has become our design target. In this work, we report the design and fabrication of a model superoleophobic surface on silicon wafer. The model surface was created by photolithography, consisting of texture made of arrays of ∼3 μm diameter pillars, ∼7 μm in height with a center-to-center spacing of 6 μm. The surface was then made oleophobic with a fluorosilane coating, FOTS, synthesized by the molecular vapor deposition technique with tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane. Contact angle measurement shows that the surface exhibits super repellency toward water and oil (hexadecane) with a water and hexadecane contact angles at 156° and 158°, respectively. Since the sliding angles for both liquids are also very small (∼10°), we conclude that the model surface is both superhydrophobic and superoleophobic. By comparing with the contact angle data of the bare silicon surfaces (both smooth and textured), we also conclude that the superoleophobicity is a result of both surface texturing and fluorination. Results from investigations of the effects of surface modification and pillar geometry indicate that both surface oleophobicity and pillar geometry are contributors to the superoleophobicity. More specifically, we found that superoleophobicity can only be attained on our model textured surface when the flat surface coating has a relatively high oleophobicity (i.e., with a hexadecane contact angle of >73°). SEM examination of the pillars with higher magnification reveals that the side wall in each pillar is not smooth; rather it consists of a ∼300 nm wavy structure (due to the Bosch etching process) from top to bottom. Comparable textured surfaces with (a) smooth straight side wall pillars and (b) straight side wall pillars with a 500 nm re-entrant structure made of SiO2were fabricated and the surfaces were made oleophobic with FOTS analogously. Contact angle data indicate that only the textured surfaces with the re-entrant pillar structure are both superoleophobic and superhydrophobic. The result suggests that the wavy structure at the top of each pillar is the main geometrical contributor to the superoleophobic property observed in the model surface. [ABSTRACT FROM AUTHOR]

Variable-temperature single-crystal X-ray diffraction, DSC (differential scanning calorimetry), and dielectric measurements show that the co-crystal system (D-HMTA)(DNBA)(0.5D2O) (1) (HMTA = hexamethylenetetramine, H-DNBA = 3,5-dinitrobenzoic acid) easily undergoes phase transitions because the H-bonds (or D-bonds) in the high-temperature phase are on the average weaker than those in the low-temperature phase; the high-temperature phase also exhibits striking isotopic effects. [ABSTRACT FROM AUTHOR]

Budesonide, as one of the inhaled glucocorticosteroids, is widely used in the treatment of asthma by pulmonary delivery. The purpose of this study was to prepare ultra-fine budesonide particles by antisolvent precipitation for dry powder inhalation. Both methanol and acetone were used to make the budesonide solution, and water was chosen as the antisolvent to induce precipitation. Hydroxypropyl cellulose and tyloxapol were added as the stabilizers. The results revealed that crystals of rectangular shape could be obtained from an acetone−water system while elliptic particles were obtained from a methanol−water system. They both had a flaky morphology, no more than 5 µm in length and 300 nm in thickness, and were formed into agglomerates. When the stabilizers were present, uniform spindle or ellipsoidal particles less than 5 µm in diameter could be prepared. All the prepared particles had the same crystalline structure as the commercial budesonide product, as assessed by X-ray diffraction. In vitroevaluation with an Aerolizer inhaler and a multistage liquid impinger (MSLI) showed that the flaky particles had better aerosol performance, because they both achieved a FPFemittedvalue of over 69%. However, the spindle or ellipsoidal particles had poor dispersibility, because of FPFemittedvalues of 23 ± 2% and 26 ± 3%, respectively. [ABSTRACT FROM AUTHOR]