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11.
This paper investigates the use of electrochemical techniques for the removal of a common herbicide, bentazone, from water
streams using a carbon-based electrode. Activated carbon cloth with high surface area and narrow micropores was used as electrode.
For a better understanding of the process, adsorption was investigated under both open circuit and controlled polarization
conditions, the latter in anodic and cathodic directions. It was found that anodic polarization enhances the kinetics of adsorption
of the herbicide on the carbon cloth, the extent of which is strongly related to the applied current value. At converse, cathodic
polarization induces the reversible desorption of the compound. Moreover, in-situ UV spectra recording on the solution did
not show any structural change of the herbicide upon polarization, demonstrating the reversibility of the process for the
regeneration of the adsorbent and the recovery of the compound. Based on these experiments, a mechanism is proposed to interpret
the reversible sorption of bentazone under polarization. 相似文献
12.
S.?Henning G.?H.?MichlerEmail author F.?Ania F.?J.?Baltá-Calleja 《Colloid and polymer science》2005,283(5):486-495
The microindentation hardness,H, of uniaxially deformed isotactic polypropylene samples was determined near the neck region, as a function of the draw ratio. The microhardness technique appears to be a valuable tool to describe mechanical properties in localized regions within a material and is capable of following changes in the semicrystalline structure during deformation. Differences in the microhardness behaviour of the two types of polymorphic forms, and , of isotactic polypropylene are discussed in terms of the two specific types of morphology, i.e. the cross-hatched arrangement of the crystalline lamellae for the form and the parallel lamellar stacking for the form. The changes of H as a function of are shown to be in accordance with the transformation in the neck from the spherulitic into the fibre structure. The steep H-decrease observed in the neck region is discussed in the light of the nanomechanical processes as revealed by scanning electron microscopy. These include lamellar separation, micro-void formation and fibrillation. Finally, microindentation experiments carried out in the neck allow an estimation of the local draw ratio at which the maximum pore content in the polypropylene samples occurs. 相似文献
13.
Ania Alik Chafiaa Bouguechtouli Manon Julien Dr. Wolfgang Bermel Rania Ghouil Dr. Sophie Zinn-Justin Dr. Francois-Xavier Theillet 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(26):10497-10501
Abundant phosphorylation events control the activity of nuclear proteins involved in gene regulation and DNA repair. These occur mostly on disordered regions of proteins, which often contain multiple phosphosites. Comprehensive and quantitative monitoring of phosphorylation reactions is theoretically achievable at a residue-specific level using 1H-15N NMR spectroscopy, but is often limited by low signal-to-noise at pH>7 and T>293 K. We have developed an improved 13Cα-13CO correlation NMR experiment that works equally at any pH or temperature, that is, also under conditions at which kinases are active. This allows us to obtain atomic-resolution information in physiological conditions down to 25 μm . We demonstrate the potential of this approach by monitoring phosphorylation reactions, in the presence of purified kinases or in cell extracts, on a range of previously problematic targets, namely Mdm2, BRCA2, and Oct4. 相似文献
14.
Ebrahim H. Ghazvini Zadeh Nader E. Abo-Dya Ania C. Sotuyo Ion Ghiviriga C. Dennis Hall 《Tetrahedron letters》2013
A convenient method toward the synthesis of α-amino acid-derived unsymmetrical ureas 2 is described herein. This route involves an interesting rearrangement of amides of N-Cbz-α-amino acids 1, which presumably entails the intermediacy of hydantoins that is followed by hydrolysis to afford unsymmetrical ureas 2 in quantitative yields and high purity. 相似文献
15.
Carboni D Flavin K Servant A Gouverneur V Resmini M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(23):7059-7065
The molecular-imprinting approach was used to obtain a nanogel preparation capable of catalysing the cross-aldol reaction between 4-nitrobenzaldehyde and acetone. A polymerisable proline derivative was used as the functional monomer to mimic the enamine-based mechanism of aldolase type I enzymes. The diketone template used to create the cavity was designed to imitate the intermediate of the aldol reaction and was bound to the functional monomer using a reversible covalent interaction prior to polymerisation. By using a high-dilution polymerisation method, soluble imprinted nanogels were prepared with dimensions similar to those of an enzyme and with the advantage of solubility and flexibility previously unattainable with monolithic polymers. Following template removal and estimation of active-site concentrations, the kinetic characterisation of both imprinted and non-imprinted nanogels was carried out with catalyst concentrations between 0.7 and 3.5 mol %. Imprinted nanogel AS147 was found to have a k(cat) value of 0.25 x 10(-2) min(-1), the highest value ever achieved with imprinted polymers catalysing C--C bond formation. Comparison of the catalytic constants for both imprinted nanogel AS147 and non-imprinted nanogel AS133 gave a ratio of k(cat 147)/k(cat 133)=18.8, which is indicative of good imprinting efficiency and highlights the significance of the template during the imprinting process. This work represents a significant demonstration of the superiority of nanogels, when the molecular-imprinting approach is used, over "bulk" polymers for the generation of catalysts. 相似文献
16.
Lucia Fernandez‐Ballester Tim Gough Florian Meneau Wim Bras Fernando Ania Francisco Jose Balta‐Calleja Julia A. Kornfield 《Journal of synchrotron radiation》2008,15(2):185-190
An experimental configuration that combines the powerful capabilities of a short‐term shearing apparatus with simultaneous optical and X‐ray scattering techniques is demonstrated, connecting the earliest events that occur during shear‐induced crystallization of a polymer melt with the subsequent kinetics and morphology development. Oriented precursors are at the heart of the great effects that flow can produce on polymer crystallization (strongly enhanced kinetics and formation of highly oriented crystallites), and their creation is highly dependent on material properties and the level of stress applied. The sensitivity of rheo‐optics enables the detection of these dilute shear‐induced precursors as they form during flow, before X‐ray techniques are able to reveal them. Then, as crystallization occurs from these precursors, X‐ray scattering allows detailed quantification of the characteristics and kinetics of growth of the crystallites nucleated by the flow‐induced precursors. This simultaneous combination of techniques allows unambiguous correlation between the early events that occur during shear and the evolution of crystallization after flow has stopped, eliminating uncertainties that result from the extreme sensitivity of flow‐induced crystallization to small changes in the imposed stress and the material. Experimental data on a bimodal blend of isotactic polypropylenes are presented. 相似文献
17.
E. García-Pérez J. B. Parra C. O. Ania A. García-Sánchez J. M. van Baten R. Krishna D. Dubbeldam S. Calero 《Adsorption》2007,13(5-6):469-476
The adsorption properties of CO2, N2 and CH4 in all-silica zeolites were studied using molecular simulations. Adsorption isotherms for single components in MFI were both
measured and computed showing good agreement. In addition simulations in other all silica structures were performed for a
wide range of pressures and temperatures and for single components as well as binary and ternary mixtures with varying bulk
compositions. The adsorption selectivity was analyzed for mixtures with bulk composition of 50:50 CO2/CH4, 50:50 CO2/N2, 10:90 CO2/N2 and 5:90:5 CO2/N2/CH4 in MFI, MOR, ISV, ITE, CHA and DDR showing high selectivity of adsorption of CO2 over N2 and CH4 that varies with the type of crystal and with the mixture bulk composition. 相似文献
18.
H. G. Kilian W. Schrodi F. Ania R. K. Bayer F. J. Baltá Calleja 《Colloid and polymer science》1991,269(9):859-866
The compressive stress-strain behavior of biaxially oriented polyethylene (PE), obtained by pressing uniaxially oriented samples, is described with the aid of the van der Waals equation of state. Results are discussed in terms of two parameters: the biaxiality (B) and the biaxial draw ratio (), which offer a measure of the strain along the two principal directions and of the average draw ratio on the film plane, respectively. Comparison of experimental and calculated data indicates that after compression up to very large deformations the maximum average strain (
m
), which is proportional to the square root of the chain length of the network, remains constant. This result supports the view that the network of entanglements is not destroyed after compression. Experiments carried out on isotropic melt crystallized PE show the presence of a network having a not very different chain length. Finally, it is shown that the segment length of this network is close to the X-ray long period of the initial structure. This result implies the existence of a high density of entanglements (two entanglements every three adjacent lamellae), which are rejected into the defective layer of the crystals. 相似文献
19.
The hydrophobic-hydrophilic character of a series of microporous activated carbons was explored as a key factor in competitive
adsorption of a non-polar compound from liquid phase. The selectivity of the carbon surface towards naphthalene was explored
by performing the adsorption isotherms in water, cyclohexane and heptane. Solvent polarity and adsorbent hydrophobic character
were found to strongly influence the adsorption capacity of naphthalene. In aqueous media, despite the non-polar character
of the adsorbate, surface acidity lowered adsorption capacity. This is attributed to the competition of water from the adsorption
sites, via H-bonding with surface functionalities and the formation of hydration clusters that reduce the accessibility and
affinity of naphthalene to the inner pore structure. In organic media the uptake decreased due to competition of the hydrophobic
solvent for the active sites of the carbon and to solvation effects. This competitive effect of the solvent is minimized in
oxidized carbons as opposed to the trend obtained in aqueous solutions. The results confirmed that although adsorption of
naphthalene strongly depends on the narrow microporosity of the adsorbent, competitive adsorption of the solvent for the active
sites becomes important. 相似文献
20.
McGovern DA Selmi A O'Brien JE Kelly JM Long C 《Chemical communications (Cambridge, England)》2005,(11):1402-1404
Photolysis of dipyrido-[3,2-a:2',3'-c]-phenazine (dppz) (1) in ethanol solution leads to the formation of 9,14-dihydrodipyridophenazine (2), which has been characterised by detailed NMR analysis, UV/VIS absorption spectroscopy, and theoretical calculations which reveal that its red colour is due to a low-lying intramolecular charge transfer state. 相似文献