Micelles of polyisobutylene-block-poly(methacrylic acid) diblock copolymers and their water-soluble interpolyelectrolyte complexes formed with quaternized poly(4-vinylpyridine)

The micellization of ionic amphiphilic diblock copolymers, polyisobutylene-block-poly(methacrylic acid) (PIB-b-PMAA), with a constant degree of polymerization of the non-ionic block and various degrees of polymerization of the polyelectrolyte block was examined in aqueous media by means of fluorescence spectroscopy using pyrene as a polarity probe. The molar values of the critical micellization concentration (cmc) were found to be around 2×10⁻⁶ mol/l, being nearly independent of the length of the polyelectrolyte block as well as pH (in the range 6-9) and ionic strength (≤0.5 M NaCl) while the specific cmc values varied from 20 to 100 mg/l. Small-angle neutron scattering (SANS) and dynamic light scattering (DLS) experiments provided evidence that aggregation numbers and hydrodynamic radii of the formed copolymer micelles are sensitive to variations of pH and ionic strength, indicating that these micelles might be ‘dynamic’ rather than ‘frozen’ ones. It was also shown by means of a combination of turbidimetry, analytical ultracentrifugation, fluorescence spectroscopy, SANS, and DLS that the formed copolymer micelles mixed with a strong cationic polyelectrolyte, poly(N-ethyl-4-vinylpyridinium bromide) at charge ratio Z=[+]/[−] not exceeding a certain critical value Z_M<1, generate peculiar water-soluble micellar complex onion-like species, each containing a two-phase hydrophobic nucleus and a hydrophilic corona. The nucleus consists of a PIB core and a shell assembled from the fragments of water-insoluble interpolyelectrolyte complex. The corona is formed by the excess fragments of poly(sodium methacrylate) blocks not involved in complexation with poly(N-ethyl-4-vinylpyridinium bromide).     

模拟CO_2埋藏不同煤级煤孔隙结构变化实验研究

使用高压超临界CO2地球化学反应器在实验室模拟CO2在地下煤层的埋藏过程,反应器中的温度为40℃,压力为9.8MPa,反应时间为72h,通过氦比重仪和压汞仪对不同煤级煤的孔隙结构变化进行了研究.结果表明:经过超临界CO2-H2O的作用后,无烟煤的真密度从1.51g/cm3增加到1.59g/cm3,其余几种煤真密度变化不大,视密度均有减小趋势,其中褐煤和瘦煤减小幅度为0.1g/cm3;褐煤总孔容变化最大,增加主要表现在大孔阶段,增幅为85%,孔隙度增幅达118%,其余煤种的总孔容和孔隙度也有不同程度增高.CO2的埋藏过程对中低煤级的影响主要是其大中孔,而对高煤级主要影响其微孔发育,无烟煤微孔孔容的增大使得煤的表面积进一步增大,从未处理的24.3m2/g增加到27.6m2/g,从而对气体的吸附能力将越来越强;对退汞曲线的滞后性分析表明,CO2的埋藏过程对"墨水瓶"孔隙度将产生一定的影响.     

Development of Fine Scale PZT Ceramic Fiber/Polymer Shell Composite Transducers

The relic processing technique was used to fabricate fine-scale piezoelectric lead zirconate titanate (PZT) ceramic fiber/polymer shell composites. In this technique sacrificial activated carbon fabrics were soaked in a PZT precursor solution, dried, and heat treated to form piezoceramic relics. Relics were embedded with polymer, which was allowed to cure, and the resulting composites were polished, electroded, and poled. Different facets of the composite- forming process were examined: structural modifications, soaking, firing, and polymer impregnation. The physical and electromechanical properties of the unique resulting composite were evaluated. Optimized PZT shell composites with 39 vol% ceramic exhibited the following property values: K ε200, tan δε5.5%, d ₃₃ε290 pC/N, d _hε100 pC/N, d _h g _hε6000 ± 10^-15 m²N, k _pε0.19, and k _tε0.28.     

Alarm response by a plethodontid salamander (Desmognathus ochrophaeus): Conspecific and heterospecific “Schreckstoff”

The detection of chemical alarm cues plays an important role for predator avoidance in many taxonomic groups, but little is known about the presence of such chemical cues in adult or caudate amphibians. We investigated the response (i.e., aversion or nonaversion) to chemical cues from damaged salamander skin and mealworms (Tenebrio molitor) in the plethodontid salamander,Desmognathus ochrophaeus. Avoidance responses were demonstrated to skin extracts of both conspecific and heterospecific salamanders. However, salamanders (D. ochrophaeus) did not avoid heated conspecific skin, fresh conspecific viscera, fresh mealworm, or freshPlethodon richmondi skin extracts. These results indicate that chemical alarm cues are: (1) present in the skin ofDesmognathus salamanders, (2) not present in mealworm or the viscera ofDesmognathus salamanders, and (3) denatured or deactivated by heating. These results also suggest that an avoidance response to chemical cues from damaged conspecifics has adaptive value in predator avoidance in terrestrial as well as aquatic vertebrates.     

Phosphorus Loss in Tile Drains from a Reclaimed Marsh Soil Amended with Manure and Phosphogypsum

Reclamation of Guadalquivir river marshes (SW Spain) constitutes a representative example of wetland reclamation in Southern Europe. Nowadays, this is an important area of tile-drained soils (40,000 ha) with an intensive irrigated agricultural production where high fertilizer rates are usually applied. In tile-drained soils, flow through macropores or cracks, which connect the nutrient rich topsoil with drain lines, can be an important pathway for nutrient transfer from soil. In order to study P loss in these soils and how it is affected by soil amendment usually applied in the zone (phosphogypsum and manure) an experiment was performed during two consecutive growing seasons on a reclaimed marsh soil from the Guadalquivir Valley. In the first season (1998–1999), sugar beet (Beta vulgaris L.) was grown under sprinkler irrigation at a rate of 2.5 mm h⁻¹; in the second (2000), cotton (Gossypium hirsutum L.) was grown under furrow irrigation at 8–10 mm h⁻¹. The amendments applied included manure (30 Mg ha⁻¹), and phosphogypsum (13 and 26 Mg ha⁻¹). Drainage events were recorded, and water samples collected and analyzed for total P (TP), dissolved total P (DTP), and dissolved reactive P (DRP). Total P in drainflow ranged from 0 to 0.818 mg l⁻¹ in the 1998–1999 season and from 0 to 0.565 mg l⁻¹ in the 2000 season. The major P form in drainflow was DRP, which accounted for about 50% of TP in the two growing seasons (the mean DRP concentration was 0.068 mg l⁻¹ in 1998–1999 and 0.043 mg l⁻¹ in 2000). Dissolved organic P accounted for a higher portion of DTP in the first season (37%) than in the second (13%). A larger load of phosphorus was observed on plots receiving manure. This treatment significantly increased (P<0.05) the cumulative drainflow during the 1998–1999 growing season (sprinkler irrigation, low drainflow rates). This is consistent with the increased losses of TP, DTP, DAHP, and DRP resulting from this treatment in this growing season. In the following season, DTP loading were significantly increased by manure (P<0.05). This seems to be related mainly to significantly increased DOP losses (P<0.01), particularly during the first drainage event. The higher fraction of applied water was lost by drainage under furrow irrigation (high drainflow rates) is consistent with the high TP load during the 2000 growing season (199–285 g ha⁻¹) relative to the 1998–1999 season (20–59 g ha⁻¹). This difference in P losses was much greater than those resulting from amendment of the soil.     

A new approach to obtain mesoporous-activated carbon via hydrothermal carbonization of Brazilian Cerrado biomass combined with physical activation for bisphenol-A removal

Abstract

The worrying hydric crisis and the increasing water contamination by emerging pollutants around the world stimulate the development of activated carbons (AC) for the removal of endocrine disruptors, including bisphenol-A (BPA). For this reason, a new approach for the synthesis of AC from hydrochar produced through hydrothermal carbonization (HTC) of Brazilian Cerrado biomass (Magonia pubescens–Sapindaceae) and physical activation using water vapor is highlighted. Compared to the traditional method of physical activation after pyrolysis, HTC was found to be better option to develop the specific surface area, porosity, and yield of the ACs, which presented mesoporous structure and carbon content higher than 80%. The BPA adsorption was evaluated by varying the contact time, BPA concentration, and pH. The Langmuir, Freundlich, and Redlich–Peterson isotherms were used to model the adsorption behavior. In the preliminary test to verify the adsorption efficiency, the AC obtained from hydrochar treated at 180?°C presented better results compared to commercial AC. The BPA adsorption data of the best treated hydrochar correlated well with the pseudo first-order model and the Langmuir isotherm (Q_max = 21.26?mg g^?1). The results of the studies indicated the combination of HTC and physical activation with steam to be an efficient way to prepare an ecologically sound adsorbent for removal of Bisphenol-A from water with lower temperature and without chemical reagents. The ACs obtained can also be potential materials for other applications, such as in the field of catalysis and environmental remediation.     

PdCl2(P(OPh)3)2 Catalyzed Coupling and Carbonylative Coupling of Phenylacetylenes with Aryl Iodides in Organic Solvents and in Ionic Liquids

Efficient cross-coupling and carbonylative coupling of terminal alkynes with aryl iodides catalyzed by PdCl₂(P(OPh)₃)₂ in the presence of NEt₃ in toluene and in ionic liquids is described. In imidazolium ionic liquids, [bmim]PF₆ or [mokt]PF₆ (bmim = 1-butyl-3-methyl imidazolium cation, mokt = 1-methyl-3-octyl imidazolium cation) catalyst was recycled and used in four concecutive catalytic cycles with high activity. In the absence of aryl iodide the same catalytic system catalyzed head-to-tail dimerization of phenylacetylene to the 1,3-diphenyl enyne, trans-PhC ≡ C–C(Ph)=CH₂, with a yield of 85%.     

Generation of novel landomycins M and O through targeted gene disruption

Two genes from Streptomyces cyanogenous S136 that encode the reductase LanZ4 and the hydroxylase LanZ5, which are involved in landomycin A biosynthesis, were characterized by targeted gene inactivation. Analyses of the corresponding mutants as well as complementation experiments have allowed us to show that LanZ4 and LanZ5 are responsible for the unique C-11-hydroxylation that occurs during landomycin biosynthesis. Compounds accumulated by the lanZ4/Z5 mutants are the previously described landomycin F and the new landomycins M and O.     

Thermodynamic studies on hydrogen adsorption on the zeolites Na-ZSM-5 and K-ZSM-5

Adsorption of dihydrogen onto the zeolites Na-ZSM-5 and K-ZSM-5 renders the fundamental H–H stretching mode infrared active. The corresponding infrared absorption bands were found at 4101 and 4112 cm⁻¹ for H₂/Na-ZSM-5 and H₂/K-ZSM-5, respectively. Thermodynamic characterization of the adsorbed state was carried out by means of variable-temperature infrared spectroscopy; simultaneously measuring integrated band intensity, temperature and equilibrium pressure of the gas phase. For the H₂/Na-ZSM-5 system, the standard adsorption enthalpy and entropy resulted to be ΔH° = −10.3 (±0.5) kJ mol⁻¹ and ΔS° = −121 (±10) J mol⁻¹ K⁻¹. For H₂/K-ZSM-5 corresponding values were −9.1 (±0.5) kJ mol⁻¹ and −124 (±10) J mol⁻¹ K⁻¹, respectively.