Topochemical modification of cotton fibres with carboxymethyl cellulose

Adsorption of carboxymethyl cellulose (CMC) as a method to introduce charged (ionizable) groups onto cellulose cotton fibre surfaces was investigated. The method was based on application of a previously published method used for wood fibres. The amount of adsorbed ionizable groups was determined indirectly by analysis of CMC in solution by the phenol–sulphuric acid method and directly by conductometric titration of the fibres. Results from the two methods correlated well. The molecular weight and purity of the CMC had an influence on its adsorption onto cotton; high molecular weight CMC was preferentially adsorbed. The adsorbed charge correlated linearly with the amount of CMC adsorbed. The total charge of the cotton fibres could be increased by more than 50% by adsorption of CMC. It is expected that this modification procedure can be used in a wide spectrum of practical applications. Lidija Fras Zemljič and Karin Stana-Kleinschek are the members of the European Polysaccharide Network of Excellence (EPNOE).     

Synthesis and properties of DNA complexes containing 2,2,6,6-tetramethyl-1-piperidinoxy (TEMPO) moieties as organic radical battery materials

We report here the first example of organic radical battery with DNA. Though there is a growing interest in DNA/cationic-lipid complexes as promising gene delivery vehicles, few efforts have been focused on the use of such complexes as advanced materials for organic optoelectronic applications. The present article describes how substitution of the sodium counter cation of DNA with cationic amphiphilic lipid(1-4) provided novel DNA-lipid complexes that contain TEMPO radicals, in which the actual mole ratio of phosphate to lipid was 1:0.84 to 1:0.16. All the TEMPO-containing DNA-lipid complexes displayed reversible two-stage charge/discharge processes, the discharge capacities of which were 40.5-60.0 A h kg(-1). In particular, the capacity of a DNA-lipid(3)-based cell reached 60.0 A h kg(-1), which corresponds to 192 % relative to its theoretical value for the single-electron one-stage process, indicating a two-electron process.     

Ultrafast excited state dynamics controlling photochemical isomerization of N-methyl-4-[trans-2-(4-pyridyl)ethenyl]pyridinium coordinated to a {Re I(CO)3(2,2'-bipyridine)} chromophore

Two multifunctional photoactive complexes [Re(Cl)(CO)(3)(MeDpe(+))(2)](2+) and [Re(MeDpe(+))(CO)(3)(bpy)](2+) (MeDpe(+)=N-methyl-4-[trans-2-(4-pyridyl)ethenyl]pyridinium, bpy=2,2'-bipyridine) were synthesized, characterized, and their redox and photonic properties were investigated by cyclic voltammetry; ultraviolet-visible-infrared (UV/Vis/IR) spectroelectrochemistry, stationary UV/Vis and resonance Raman spectroscopy; photolysis; picosecond time-resolved absorption spectroscopy in the visible and infrared regions; and time-resolved resonance Raman spectroscopy. The first reduction step of either complex occurs at about -1.1 V versus Fc/Fc(+) and is localized at MeDpe(+). Reduction alone does not induce a trans-->cis isomerization of MeDpe(+). [Re(Cl)(CO)(3)(MeDpe(+))(2)](2+) is photostable, while [Re(MeDpe(+))(CO)(3)(bpy)](2+) and free MeDpe(+) isomerize under near-UV irradiation. The lowest excited state of [Re(Cl)(CO)(3)(MeDpe(+))(2)](2+) has been identified as the Re(Cl)(CO)(3)-->MeDpe(+ 3)MLCT (MLCT=metal-to-ligand charge transfer), decaying directly to the ground state with lifetimes of approximately 42 (73 %) and approximately 430 ps (27 %). Optical excitation of [Re(MeDpe(+))(CO)(3)(bpy)](2+) leads to population of Re(CO)(3)-->MeDpe(+) and Re(CO)(3)-->bpy (3)MLCT states, from which a MeDpe(+) localized intraligand (3)pipi* excited state ((3)IL) is populated with lifetimes of approximately 0.6 and approximately 10 ps, respectively. The (3)IL state undergoes a approximately 21 ps internal rotation, which eventually produces the cis isomer on a much longer timescale. The different excited-state behavior of the two complexes and the absence of thermodynamically favorable interligand electron transfer in excited [Re(MeDpe(+))(CO)(3)(bpy)](2+) reflect the fine energetic balance between excited states of different orbital origin, which can be tuned by subtle structural variations. The complex [Re(MeDpe(+))(CO)(3)(bpy)](2+) emerges as a prototypical, multifunctional species with complementary redox and photonic behavior.     

Water-soluble, electroactive, and photoluminescent quaterthiophene-dinucleotide conjugates

Quaterthiophene-dinucleotide conjugates 5'TA3'-t4-3'AT5', 5'AA3'-t4-3'AA5', and 5'TT3'-t4-3'TT5' (TA: thymidine-adenosine, AA: adenosine-adenosine, TT: thymidine-thymidine) were synthesized and analyzed by a combination of spectroscopy and microscopy, electrical characterization, and theoretical calculations. Circular dichroism (CD) experiments demonstrated a transfer of chirality from the dinucleotides to quaterthiophene at high ionic strength and in cast films. The films were photoluminescent and electroactive. CD and photoluminescence spectra and current density/voltage plots (measured under dynamic vacuum) displayed significant variation on changing the dinucleotide scaffold. Molecular mechanics and molecular dynamics calculations indicated that the conformation and packing modes of the conjugates are the result of a balance between intra- and intermolecular nucleobase-thiophene stacking interactions and intramolecular hydrogen bonding between the nucleobases.     

A selective colorimetric chemosensor for thiols based on intramolecular charge transfer mechanism

Compound 1 as an electron donor-acceptor compound with N,N-dimethylaniline and quinone units was designed for a highly selective colorimetric determination of thiol-containing amino acids and peptides, by making use of the unique reactivity of thiol towards quinone. Compound 1 shows a strong intramolecular charge transfer (ICT) band around 582 nm; but, it decreased after addition of either cysteine (Cys) or glutathione (GSH). Moreover, the ICT band intensity at 582 nm decreased linearly with the increasing concentrations of Cys or GSH. The interference from other amino acids can be neglected. Therefore, compound 1 can be employed as a selective colorimetric visual chemosensor for thiol-containing amino acids and peptides.     

Localized electron traps on extended molecular surfaces

We have previously alluded to the fact that concentrated charge pockets can form on molecular surfaces that can act to stabilize excess electrons. These charge pockets are formed from systems, which posses a network of hydrogen bonded OH groups on one side of the surface and hydrogen atoms on the opposite side of the molecular surface. In this work, we have increased the size of our recently reported molecular surfaces (Jalbout and Adamowicz, Mol Phys, 2006, 19, 3101) while keeping the number of OH groups constant, to investigate localized charge concentration on extended frameworks. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

硫酸溶液中1,1'-硫代羰基二咪唑在碳钢上的吸附及缓蚀影响和碘离子的增强应

The inhibition effect of 1,1'-thiocarbonyldiimidazole (TCDI) on the corrosion behaviors of mild steel impedance spectroscopy(EIS),and linear polarization resistance(LPR)techniques.The effect of immersion time on the inhibition effect of TCDI was also investigated over 72 h.For the long.term tests.hydrogen evolution with immersion time(VH2-t)was measured in addition to the three techniques already mentioned.The thermodynamic parameters.such as adsorption equilibrium constant(Kads) and adsorption free energy(△Gads)values,were calculated and discussed.To clarify inhibition mechanism,the synergistic effect of iodide ion was also investigated.The potential of zero charge (PZC)of the MS was studied by electrochemical impedance spectroscopy method.and a mechanism of adsorption process was proposed.It was demonstrated that inhibition efficiency increased with the increase in TCDI concentration and synergistically increased in the presence of KI.The inhibition efficiency was discussed in terms ofadsorption of inhibitormolecules on the metal surface and protective film formation.     

Infection Microenvironment-Sensitive Photothermal Nanotherapeutic Platform to Inhibit Methicillin-Resistant Staphylococcus aureus Infection

Methicillin-resistant Staphylococcus aureus (MRSA) can induce multiple inflammations. The biofilm formed by MRSA is resistant to a variety of antibiotics and is extremely difficult to cure, which seriously threatens human health. Herein, a nanoparticle encapsulating berberine with polypyrrole core and pH-sensitive shell to provide chemo-photothermal dual therapy for MRSA infection is reported. By integrating photothermal agent polypyrrole, berberine, acid-degradable crosslinker, and acid-induced charge reversal polymer, the nanoparticle exhibited highly efficient MRSA infection treatment. In normal uninfected areas and bloodstream, nanoparticles showed negatively charged, demonstrating high biocompatibility and excellent hemocompatibility. However, once arriving at the MRSA infection site, the nanoparticle can penetrate and accumulate in the biofilm within 2 h. Simultaneously, berberine can be released into biofilm rapidly. Under the combined effect of photothermal response and berberine inhibition, 88.7% of the biofilm is removed at 1000 µg mL⁻¹. Moreover, the nanoparticles have an excellent inhibitory effect on biofilm formation, the biofilm inhibition capacity can reach up to 90.3%. Taken together, this pH-tunable nanoparticle can be employed as a new generation treatment strategy to fight against the fast-growing MRSA infection.     

Activation-induced layered structure in NiCoAl by atomic modulation for energy storage application

The surface activation of alloys favors their electrochemical interactions, ion diffusivity, and the rapid kinetics of ions and electrons, leading to the formation of self-supported layered double hydroxides (LDHs) in them. However, the formation of LDHs at different depths in the alloy upon activation, their electronic/atomic structures, and their electrochemical charge storage mechanism, have not been thoroughly explored. Herein, Ni ion-substituted CoAl alloys are prepared by arc melting and activated by KOH electrolyte, which is responsible for the modulation of the atomic configuration as confirmed by XRD. Raman depth mapping demonstrates how the LDHs vary with depth upon activation and that the octahedral and tetrahedral symmetry sites of CoO and Co₃O₄ are responsible for the formation of the layered structures of CoOOH and Co(OH)₂, respectively. The activated Ni₁₀Co₈₅Al₅ has a superior volumetric capacitance of 4.15 F/cm³ at 0.5 mA/g, which is 38.6 times that of an unactivated one, and excellent cyclic stability up to 5000 cycles, and a voltage of 0.54 V generated from a fabricated supercapacitor cell. X-ray Absorption Spectroscopy (XAS) analysis indicates greater charge transfer by Co than by Ni and the modulation of the local atomic structures facilitates electrochemical charge storage in Ni₁₀Co₈₅Al₅. This work presents an easy route for the development of advanced LDHs, and the mechanism of electrochemical charge storage in them.     

Effect of Antioxidant System on Aging Properties of Poly(1-butene) and the Aging Mechanism

The aging property of poly(1-butene) in which different antioxidant systems were added was characterized by its physical and mechanical properties before and after aging for 300 h in a hot air aging box. In addition, the oxidation induction time (OIT) of all designed samples was tested. The result demonstrated that the primary antioxidant pentaerythritol tetrakys 3-(3,5-ditert-butyl-4-hydroxyphenyl) propionate performed better than n-octadecyl-β-(4-hydroxy-3,5-di-tert -butyl-phenyl)-propionate. The anti-aging effect of the secondary antioxidant was ranked in the order bis-(2,4-di-tert-butyl-pheny)-phosphiterythritol diphosphite better than tns-(2.4-di-tert-butyl)-phosphite, with both better than distearyl thiodipropionic acid. Confirmation of oxidation of the polymer was made by IR analysis and a general oxidation mechanism scheme for poly(1-butene) is presented.