Degradation of lignin by ozone. I. The kinetics of lignin degradation of ozone

The ozonolysis of spruce periodate and cuoxam lignins and protolignin in spruce wood has been studied in 45% aqueous acetic acid at room temperature. Stirring affected the rate of reaction and a tentative explanation is given. Degradation followed first-order kinetics characterized by a rate constant K with values of 6.96 × 10^?4s^?1 for periodate lignin, 5.10 × 10^?4s^?1 for cuoxam lignin, and 5.09 × 10^?4s^?1 for protolignin in spruce wood. The similarity of the rate constants shows (1) that periodate and cuoxam lignins are good models for wood lignin and (2) that the carbohydrate matrix has an insignificant effect on the rate of delignification of the protolignin by ozone. The average rate of ozone consumption per C₉ unit for periodate lignin was determined as 0.12 mol/min and 0.08 mol/min for cuoxam lignin. The implications of the various results are discussed.     

Rapid Characterization of Wood Pulp Lignin by Fourier Transform Raman Spectroscopy

FT-Raman spectroscopy is used for the rapid measurement of wood pulp lignin. A total of 23 western softwood pulp samples with known kappa numbers (10–38) are used. Each sample is divided into three portions and scanned separately. The integrated area of the lignin band at approximately 1600 cm⁻¹is ratioed against the integrated area of the cellulose bands in the 1200–1010 cm⁻¹region and correlated to known kappa numbers. The measured ratios behave linearly with the kappa number (r= 0.99) and can be reproducibly determined with an error of approximately 2% or less. The data are presented and discussed in view of the potential for at-line analysis of lignin associated with chemical delignification of wood pulp.     

Efficacy of selected triorganotin(IV) compounds on leaves against Phytophthora palmivora (Butler) Butler isolated from black pepper and cocoa

Several triorganotin(IV) compounds and Terrazole® 35 WP were screened for their in vitro antifungal activity against three isolates of Phytophthora palmivora. Two isolates (isolates Phy. 2 and Phy. 334) were obtained from black pepper (Piper nigrum L.) and one isolate (isolate Phy. 56) from cocoa leaves (Cacao theobromae). ED₅₀ values for radial growth of the isolates ranged from 0.09 to 1,700 μg cm^?3 for the triorganotin(IV) compounds and from 3.46 to 1 227 000 μg cm^?3 for Terrazole®. Diphenylbutyltin bromide exhibited the highest antifungal activity against the three isolates of P. palmivora with ED₅₀ values ranging from 0.30 to 0.73 μg cm^?3. Diphenylbutyltin bromide was equally effective against a freshly isolated virulent culture of P. palmivora (isolate Phy. 346) from black pepper leaves in Sarawak, East Malaysia, yielding an ED₅₀ value for radial growth of 0.87 μg cm^?3 and a probit-log concentration regression line slope value of 1.04. In vitro efficacy of diphenylbutyltin bromide against isolate Phy. 346 using detached healthy pepper leaves showed 40–75% infection of leaves at 100 μg cm^?3 and no infection at 500 μg cm^?3. Diphenylbutyltin bromide at 100 μg cm^?3, however, inhibited the diameter of lesion by 43.3–73.7% compared with the untreated controls. Black pepper leaves treated with Terrazole® at 778 μg cm^?3 exhibited 5.3–33.3% inhibition of lesion diameter compared with the untreated controls, where 90–100% of the leaves were infected. Concentrations of diphenylbutyltin bromide of 1000–2500 μg cm^?3 caused some injury lesions on the leaves. From the results obtained, it appears that diphenylbutyltin bromide could be used as a protective spray or drench against P. palmivora infection of black pepper at 100–500 μg cm^?3.     

Theoretical and experimental infrared spectra of hydrated and dehydrated Nafion

The time‐dependent IR spectra during dehydration of fully hydrated Nafion show the reversible disappearance of the 1061 cm^?1 and 969 cm^?1 concurrent with the emergence of peaks at ～928 cm^?1 and ～1408 cm^?1. The first pair of group modes is associated with a dissociated exchange group (sulfonate) with a local C_3V symmetry. The C_3V group modes shift with state‐of‐hydration: The 969 cm^?1 peak completely vanishes and the 1061 cm^?1 is reduced to a small shoulder at 1070 cm^?1 at end of dehydration. The C_3V group modes are replaced by the pair of group modes of an associated exchange group (sulfonic acid) with C₁ local symmetry. The density functional theory normal mode analysis confirms that the sulfonic acid/sulfonate site plays a dominant role in the C₁ and C_3V group modes, respectively. This work clarifies the importance of assigning fluoropolymers peaks as group modes rather than traditional single functional group assignments as is often the case with the ～1061 cm^?1 and ～969 cm^?1 C_3V group modes. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1329–1334     

Comparative study of photodegradation of wood by a UV laser and a xenon light source

A detailed study of photodegradation of wood surfaces by xenon light source and a UV laser has been carried out. Silver birch, rubberwood, Scots pine and chir pine wood veneers were irradiated with a xenon light source or a 244 nm argon ion laser. The changes in chemical structure of wood surfaces were monitored by UV resonance Raman (UVRR), photoacoustic Fourier transform infrared (FTIR-PAS) and UV-vis reflectance spectroscopies. The depth profile of xenon lamp irradiated wood surfaces was carried out by measuring FTIR-PAS spectra at different moving mirror velocities. The UVRR and FTIR-PAS spectra of irradiated wood surfaces showed degradation of aromatic structure in lignin combined with strong formation of carbonyl structures. The FTIR-PAS spectra measured from xenon irradiated wood surfaces indicate that hardwood lignin degrades at a faster rate than softwood lignin. The UVRR spectra of xenon irradiated wood show a significant decrease in the intensities of aromatic structures at 1602 cm⁻¹. This is accompanied by a significant band broadening and notable shift towards longer wavenumbers, which has been attributed to the formation of o- and p-quinone structures as degradation products. The formation of quinone structures was also supported by the generation of a broad absorption band between 350 and 600 nm in UV-vis reflectance spectra of irradiated wood surfaces. There was a significant broadening in the region of 1500-1000 cm⁻¹ in UVRR spectra due to the formation of unsaturated structures as a result of lignin degradation. The UVRR spectra of laser irradiated wood showed similar behaviour i.e., overall broadening and a rapid reduction in the intensity of lignin aromatic structure. The rate of degradation by laser was very high. However, the extent of band broadening was higher in xenon irradiated wood indicating the generation of several different types of structures as compared to laser irradiation, which produces only particular type of structures. UVRR spectra of laser irradiated Whatman paper showed significant photodegradation of cellulose by UV laser. The UV degradation rate of lignin was much higher than cellulose.     

Determination of airborne wood dust in Button samples by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)

Emerging concerns regarding the toxicity of inhaled wood dust support the need for techniques to quantitate wood content of mixed industrial dusts. The diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis technique was applied to the determination of wood content of 181 inhalable dust samples (geometric mean concentration: 0.895?mg/m³; geometric standard deviation: 2.73) collected from six wood product industry factories using 25?mm glass fibre filters with the Button aerosol sampler. Prior to direct DRIFTS analysis the filter samples were treated with ethyl acetate and re-deposited uniformly. Standards ranging from 125?µg to 4000?µg were prepared for red oak, southern yellow pine, and red cedar and used for quantitation of samples depending upon the wood materials present at a given factory. The oak standards spectra were quantitated by linear regression of response in Kubelka-Munk units at 1736?cm^?1, whereas the pine standards and the cedar standards spectra were quantitated by polynomial regression of response in log 1/R units at 1734?cm^?1, with the selected wavenumbers corresponding to stretching vibration of free C=O from cellulose and hemicelluloses. For one factory which used both soft- and hard-woods, a separate polynomial standard curve was created by proportionally combining the oak and pine standards polynomial regression equations based on response (log 1/R) at 1734?cm^?1. The analytical limits of detection were approximately 52?µg of oak, 20?µg of pine, 30?µg of cedar, and 16?µg of mixed oak and pine for the factory with mixed woods. Overall, the average of dry wood dust percentage of inhalable dust was approximately 56% and the average dry wood dust weight was 0.572?mg for the Button samples. Across factories, there were statistically significant differences (p?<?0.001) for the percentage of dry wood dust in inhalable dust with factory averages ranging from 33.5 to 97.6%.     

Investigation of the chemical modifications of beech wood lignin during heat treatment

Holocellulose, Klason lignin and milled wood lignin (MWL) of beech wood were extracted before and after heat treatment and analysed using CP MAS ¹³C NMR, ¹³C NMR, ³¹P NMR and size exclusion chromatography (SEC). Experimental results showed that the thermal treatment degrades hemicelluloses and affects lignin polymer through depolymerisation due mainly to cleavage of β-aryl-ether linkages and recondensation reactions. The spectroscopic analysis of MWL demonstrated that these recondensation reactions involved mainly guaiacyl units through formation of 5,5′-biphenolic and diarylmethane structures.Analysis of molecular weight distribution of MWL by SEC indicated that average molecular weights of heat treated milled wood lignin were lower than those of native milled wood lignin.     

Structure of Alkali Lignins Fractionated from Ricinus communis and Bagasse. 3. IR Spectra

Abstract

The lignin fractions isolated by one- and multistage soda and sulfate cookings showed almost identical IR spectra, indicating the similarity of the lignin skeletal structure throughout the plant. However, the absorbances reveal some differences. Similarity of the spectra includes: 1) chelation and bonding of the hydroxyl groups. 2) Stretching vibration of C-H bonds in methyl, methoxyl, and methylene groups. 3) Stretching vibration of C≡N. 4) Carbonyl unconjugated β-ketone, conjugated acids, or esters at 1725 cm^?1. There is no change in the intensity of absorption at this band from that at 1515 cm^?1 with the cooking stage. 5) Aromatic skeletal vibration at 1610 and 1515 cm^?1, affected by ring substituents at 1425 cm^?1. 6) The band at 1465 cm^?1 showed a higher intensity for soda and soluble kraft lignins than for insoluble kraft ones. 7) The band at 1370 cm^?1, assigned to phenolic OH bending, is affected by the methoxyl group. 8) The absence of condensed guaiacyl and the presence of syringyl and uncondensed guaiacyl. Assignments for hardwood lignin are shown for soda and soluble kraft lignins of bagasse, while those for softwood lignin are shown for soda, soluble, and insoluble kraft lignins of Ricinus communis and for insoluble kraft lignin of bagasse. A relation exists between the carbohydrate's lignin and the band at 920 cm^?1. Lignins from Ricinus communis are of higher guaiacyl to syringyl ratios than those from bagasse. The presence of C—S vibration and the absence of thiol groups for kraft lignins are indicated.     

X‐ray photoelectron spectroscopy study of red oak‐ (Quercus rubra), black cherry‐ (Prunus serotina) and red pine‐ (Pinus resinosa) extracted wood surfaces

The X‐ray photoelectron spectroscopy (XPS) study of black cherry (Prunus serotina), red oak (Quercus rubra), and red pine (Pinus resinosa) wood samples extracted with ethanol, ethanol—toluene, and water was conducted to evaluate chemical modifications occurring on the wood surface due to wood extractives, and derive possible implications for wood utilization. Results obtained indicate an increase in the O/C values following extraction treatments due to the partial removal of high carbon content extractives. The C 1s peaks indicated a decrease in the area of the C1 peak, known to originate from lignin and extractives following extraction. At the same time, a rise in the C₂ peak (mainly originating from cellulose and hemicelluloses) was observed, indicating that more cellulose was exposed on the wood surface following extraction. The O 1s peaks showed an increase in the O₁ peak originating from cellulose, therefore confirming the trend observed for C 1s peaks. These results suggest that extracted wood is more wettable because of the increased exposure of high‐oxygen‐content cellulose molecules, known to be more hydrophilic than lignin and high carbon content extractives. Copyright © 2005 John Wiley & Sons, Ltd.     

Realtime Monitoring of Xylitol Fermentation by Micro-Raman Spectroscopy

The fermentation of xylitol is a promising alternative to conventional chemical processes. Micro-Raman spectroscopy was used to monitor the process involving Candida tropicalis, including the medium and yeast cells during xylitol fermentation. The spectra of the fermentation medium showed that the characteristic xylitol peak at 866 cm^?1 was enhanced from 18 h and that the characteristic xylose peak at 901 cm^?1 gradually diminished as the reaction progressed. The characteristic ethanol peak at 880 cm^?1 indicated the production of by-products. Intracellular biological macromolecules, such as nucleic acids, proteins, lipids, and carbohydrates, were identified in the spectra of yeast cells. The intensity of nucleic acids at 783 cm^?1 reached the highest value after 3 h. The xylose band at 901 cm^?1 and the peaks in the carbohydrate region reached a maximum in the logarithmic phase, indicating the carbohydrate metabolism was the most active. The amide I band located at 1658 cm^?1 indicated the major secondary structure of proteins was α-helix; its intensity gradually reduced during the fermentation. The 853 cm^?1 band due to buried tyrosine was predominant at 21 h. In addition, the 1275 cm^?1 band corresponded to the presence of a random coil only at 27 h. These results provided a perspective to understand fermentation and verified the applicability of Raman spectroscopy in xylitol fermentation.     

Side‐chain effects on phenothiazine‐based donor–acceptor copolymer properties in organic photovoltaic devices

A series of new phenothiazine‐based donor–acceptor copolymers, P1 and P2, were synthesized via a Suzuki coupling reaction. The weight‐averaged molecular weights (M_w) of P1 and P2 were found to be 16,700 and 16,100, with polydispersity indices of 1.74 and 1.39, respectively. The UV–visible absorption spectra of the polymer thin films contained three strong absorption bands in the ranges 318–320 nm, 430–436 nm, and 527–568 nm. The absorption peaks at 320 and 430 nm originated mainly from the phenothiazine‐based monomer units, and the longer wavelength absorption band at 527–568 nm was attributed to the increased effective conjugation length of the polymer backbones. Solution‐processed field‐effect transistors fabricated with these polymers exhibited p‐type organic thin film transistor characteristics. The field‐effect mobilities of P1 and P2 were measured to be 1.0 × 10^?4 and 7.5 × 10^?5 cm² V^?1 s^?1, respectively, with on/off ratios in the order of 10⁴ for all polymers. A photovoltaic device in which a P2/PC₇₁BM (1/3) blend film was used as the active layer exhibited an open‐circuit voltage (V_OC) of 0.70 V, a short‐circuit current (J_SC) of 6.79 mA cm⁽², a fill factor of 0.39, and a power conversion efficiency of 1.86% under AM 1.5 G (100 mW cm^?2) illumination. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Beech Lignin—Proposal of a Constitutional Scheme

The high molecular weight material lignin consists of phenylpropane units linked together by a variety of bond types. During the past eight years, two newly developed degradation procedures have permitted the first direct determinations of the nature of these bonds. The first procedure affords a very mild partial hydrolysis of benzyl ether bonds. Eleven dimeric, trimeric, and tetrameric degradation products were obtained in this way from spruce and beech lignin: they exhibited three different kinds of bonds between the C₉ structural units, and their structures have all been elucidated. In the second procedure, the most important kind of bond in lignin, i. e. the arylglycerol-β-aryl ether bond, can be subjected to directed cleavage under mild conditions after introduction of a suitable neighboring group. On application to beech lignin, 91 % of the material was degraded giving monomeric to tetrameric phenols. Complete structural elucidation of the twenty dimeric phenols isolated and a knowledge of their relative yields and the yields of the other fractions obtained by gel filtration permitted a structural scheme to be set up for beech lignin in which the C₉ structural units are linked together by no less then ten different kinds of bonds. The structural scheme, which can be readily explained biogenetically, has the same elemental composition as natural beech lignin. Further support for the structural scheme comes from a comparison of the ¹³C-NMR spectrum of natural beech lignin and a ¹³C-NMR spectrum calculated for the proposed structure on the basis of about fifty lignin model substances.     

Synthesis of SET–LRP‐induced galactoglucomannan‐diblock copolymers

Polysaccharides are biorenewable and biodegradable starting materials for the development of functional materials. The synthesis of a monofunctional macroinitiator for single electron transfer‐living radical polymerization was successfully developed from a wood polysaccharide‐O‐acetyl galactoglucomannan (GGM) using a beforehand synthesized amino‐functional α‐bromoisobutyryl derivative applying reductive amination. The GGM macroinitiator was employed to initiate a controlled radical polymerization of [2‐(methacryloyloxy)ethyl]trimethylammonium chloride (MeDMA), methyl methacrylate (MMA), and N‐isopropylacrylamide (NIPAM) using Cu⁰/Me₆‐Tren as a catalyst. The either charged or amphiphilic GGM‐b‐copolymers with different chain lengths of the synthetic block were successfully synthesized without prior hydrophobization of the GGM chain and dimethyl sulfoxide (DMSO) or DMSO/water mixtures were used as solvents. This novel synthetic approach may find untapped potentials particularly for the development of polysaccharide‐based amphiphilic additives for cosmetics or paints and for the design of novel temperature or pH responsive polymers with such potential applications as in drug delivery systems or in biocomposites. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5100–5110     

Differentiation of Rhizoma Curcumas Longae and Radix Curcumae by a Multistep Infrared Macro-Fingerprint Method

A multistep infrared macro-fingerprint method was applied to identify two Chinese herbal drugs, Rhizoma Curcumas Longae (RCL) and Radix Curcumae (RC). Fourier transform infrared (FT-IR) spectra of the two were similar to each other and consistent with the 11 peaks of the spectrum of starch. RCL had a characteristic absorption peak at approximately 1514 cm^?1 that correlated to the strong peak near 1509 cm^?1 of curcumin. Between 900 cm^?1–1700 cm^?1 of the second derivative infrared (SD-IR) spectra, with higher resolution, RCL, and curcumin had 10 common peaks. In the FT-IR and SD-IR spectra of the ethanol extract, the spectra of the RCL extract and curcumin were similar, but RC was different. According to the fingerprint characteristics of the infrared spectra for RC and its extracts, the strongest peak at 1055 cm^?1; the C-O absorption peaks at 1124 cm^?1, 1106 cm^?1, and 996 cm^?1; and the strong methylene peaks at 2925 cm^?1 and 2853 cm^?1 suggest that RC contains more saccharides. In the range of 1350 cm^?1–1700 cm^?1, RCL and RC had similar two-dimensional infrared (2D-IR) correlation spectra. Both of them had three autopeaks, but the autopeaks were located at 1458 cm^?1, 1560 cm^?1, and 1641 cm^?1 for RCL and 1458 cm^?1, 1560 cm^?1, and 1669 cm^?1 for RC, suggested that the aromatic components of the two were not identical. The average correlation for the 18 RCL and 18 RC samples were 0.9906 and 0.9878, respectively, and this method achieves a good classification of the sample type.     

Enzymatic degradation of Lignin-Carbohydrate complex (part I)

Initial steps in an early metabolic pathway of biodegradation of lignin by white-rot fungus are very important for application of biotechnology to the utilization of biomass; for example, enzymatic pretreatment for ethanol production from plant resources and biological pulping. Lignins in woody plants exist as giant high molecular weight compounds bounded with carbohydrates, mainly hemicelluloses at middle lamella and in secondary cell wall, and show resistance against the invasion of general microorganisms other than wood-rotting fungi and also against enzymatic digestion of cellulose. We assumed that white-rot fungi first attack the lignin-carbohydrate complex (LCC) and then decompose to some degree into oligomers of lignin and hemicellulose by an unknown enzymatic reaction. The study began with a screening of the fungus, which grew well on the LCC medium. LCCs were prepared from wood meal ofPicea jezoensis that had been extracted MWL, by the method of Koshijima (1). Six fungi (2) that grew well on the media containing decayed lignin were inoculated on agar media of LCC. After 3 d cultivation, the fungiGanoderma sp. andPoria subacida showed most growth on the medium. Crude enzyme preparations were made from decayed wood meal media with each fungus. Chromatographic detection of decomposed compounds from LCC, which is soluble in hot water, by each enzyme and Meicelase fromTricoderma viride, suggest that the wood-rotting fungus may contain another enzyme able to liberate a phenolic compound from LCC besides the enzymes ofTricoderma viride.     

Kinetics of the reactions of CH3 with O(3P) and O2 at 295 K

The reactions of CH₃ radicals with O(³P) and O₂ have been studied at 295 K in a gas flow reactor sampled by a mass spectrometer. For the reaction between CH₃ and O, conditions were such that [O] » [CH₃] and the methyl radicals decayed under pseudo-first-order conditions giving a rate coefficient of (1.14 ± 0.29) × 10^?10 cm³/s. The reaction between CH₃ and O₂ was studied in separate experiments in which CH₃ decayed under pseudo-first-order conditions. In this case, the rate coefficient obtained increased with increasing concentration of the helium carrier gas. This was varied over the range of 2.5–25 × 10¹⁶ cm^?3, resulting in values for the apparent two-body rate coefficient ranging from 1 × 10^?14 to 5.2 × 10^?14 cm³/s. No evidence was found for the production of HCHO by a direct two-body process involving CH₃ + O₂, and an upper limit of 3 × 10^?16 cm³/s was placed on the rate coefficient for this reaction. The experimental results for the apparent two-body rate coefficient exhibit the curvature one would expect for an association reaction in the fall-off region. Calculations used to extrapolate these measurements to the low-pressure limit yield a value for k₀ of (3.4 ± 1.1) × 10^?31 cm⁶/s, which is more than a factor of 2 higher than previous estimates.     

TG-FTIR studies on lignin-based polycaprolactones

Thermal degradation behaviour of alcoholysis lignin-based polycaprolactones (ALPCL's) with various molar ratios of β-caprolactone monomer to each hydroxyl group of lignin (CL/OH ratios) was studied by TG-FTIR. The temperature was varied from 20 to 800°C. Thermal degradation temperatures (T_d's) of alcoholysis lignin (AL) and ALPCL's were determined using TG curves. T_d increased with increasing CL/OH ratio, suggesting that AL becomes thermally stable after the derivatization with PCL chains. Mass residue (MR) at 500°C was also determined using TG curves. MR values decreased with increasing CL/OH ratios. The evolved gases formed by thermal degradation of ALPCL's at various temperatures were simultaneously analyzed by FTIR. The main peaks observed for the samples are as follows: wavenumber (assignment): 1160 cm^-1 (vC-O-), 1260 cm^-1(-C(=O)-O-C-), 1517 and 1617 cm^-1 (vC=C), 1770 cm^-1 (vC=O), 2345 cm^-1 (vCO2), 2945 cm^-1 (vC-H) and 3700 cm^-1 (vOH). It was found that the peak intensities for C=O, CH, C-O-C, OH peaks, which were observed for evolved gases at 430°C, increased with increasing CL/OH ratios, suggesting that the evolved gases at 430°C are mainly formed by thermal degradation of PCL chains in ALPCL's. This revised version was published online in July 2006 with corrections to the Cover Date.     

Changes in lignin and cellulose by irradiation

The effect of high-energy radiation on wood and cellulose was investigated. By irradiation of beech wood, changes in lignin, in carbohydrates and in wood structure take place. Furthermore, new lignin carbohydrate complexes are formed. A way is shown to prevent undesirable reactions. Irradiated pulp possesses a lower degree of polymerization and a higher accessibility for chemical reactions. Processing irradiated pulp to viscose fibres will be more efficient.     

Development of a Carbon Paste Electrode Modified with Reduced Graphene Oxide and an Imidazole Derivative for Simultaneous Determination of Biological Species of N‐acetyl‐L‐cysteine,Uric Acid and Dopamine

In this work, the modified carbon paste electrode (CPE) with an imidazole derivative 2‐(2,3 dihydroxy phenyl) 4‐methyl benzimidazole (DHPMB) and reduced graphene oxide (RGO) was used as an electrochemical sensor for electrocatalytic oxidation of N‐acetyl‐L‐cysteine (NAC). The electrocatalytic oxidation of N‐acetyl‐L‐cysteine on the modified electrode surface was then investigated, indicating a reduction in oxidative over voltage and an intensive increase in the current of analyte. The scan rate potential, the percentages of DHPMB and RGO, and the pH solution were optimized. Under the optimum conditions, some parameters such as the electron transfer coefficient (α) between electrode and modifier, and the electron transfer rate constant) k_s) in a 0.1 M phosphate buffer solution (pH=7.0) were obtained by cyclic voltammetry method. The diffusion coefficient of species (D) 3.96×10^?5 cm² s^?1 was calculated by chronoamperometeric technique and the Tafel plot was used to calculate α (0.46) for N‐ acetyl‐L‐cysteine. Also, by using differential pulse voltammetric (DPV) technique, two linear dynamic ranges of 2–18 µM and 18–1000 µM with the detection limit of 61.0 nM for N‐acetyl‐L‐cysteine (NAC) were achieved. In the co‐existence system of N‐acetyl‐L‐cysteine (NAC), uric acid (UA) and dopamine (DA), the linear response ranges for NAC, UA, and DA are 6.0–400.0 µM, 5.0–50.0 µM and 2.0–20.0 µM, respectively and the detection limits based on (C=3s_b/m) are 0.067 µM, 0.246 µM and 0.136 µM, respectively. The obtained results indicated that DHPMB/RGO/CPE is applicable to separate NAC, uric acid (UA) and dopamine (DA) oxidative peaks, simultaneously. For analytic performance, the mentioned modified electrode was used for determination of NAC in the drug samples with acceptable results, and the simultaneous determination of NAC, UA and DA oxidative peaks was investigated in the serum solutions, too.     

Preparation of a solution‐processable,nanostructured ionic polyacetylene

Polymerization of a self‐assembled 1‐dodecyl‐3‐propargylimidazolium bromide ionic liquid (IL) yields a nanostructured ionic polyacetylene. A 1:1 aqueous mixture of the amphiphilic IL produces an ordered lyotropic mesophase that adopts a hexagonal perforated lamellar structure. Rh (I)‐mediated polymerization of the assembled mixture yields a hexagonal modulated lamellar structured polymer. FTIR spectroscopy reveals that the polymer was self n‐doped. The polymer was fractioned into three components with the majority product, possessing an intermediate molecular weight that is soluble in polar organic solvents. In methanol, the optical band gap of the main fraction was determined to be 2.38 eV and was nonemissive. The solution‐processable polymer was airbrush sprayed onto glass substrates to give a liquid‐crystalline, lamellar structured semiconductive film (7.02 × 10^?5 S cm^?1). The polymer resisted oxidation (degradation) upon storage in air as monitored by vibrational spectroscopy. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1215–1227