Red pigment-forming substances from autoxidized linolenate: Identification of prostaglandin-like substances

The chemical structures of lipid degradation products capable of reacting with amino acids and forming red pigments were investigated. The red pigment-forming substances (RPS's) derived from autoxidized linolenate in triglyceride of linseed oil were purified successively by gel chromatography on Sephadex LH-20, column chromatography and TLC on Silica gel 60, and HPLC on μ-Porasil. Consequently, three types of RPS's were isolated. IR spectra of RPS's were similar, except for slight differences in the fingerprint region (1300—650 cm⁻¹). These substances included the OH group (3500 cm⁻¹ region), conjugated aldehyde (νC=0 1688 cm⁻¹, νC=C 1635 cm⁻¹) and ketone (νC=0 1740 cm⁻¹) in their molecules. RPS's were analyzed by GLC and GC-MS after derivatization with dimethylhydrazine and/or trimethylsilyl reagents, before and after the reduction with NaBH₄ and/or hydrogenation with PtO₂. The fragmentation patterns indicated the presence of an ethyl group in addition to the functional groups described above, and the molecular formula was estimated to be C₁₀H₁₄O₃. Further elucidation of the structures was obtained by¹³C- and¹H-NMR analyses, and evidence was obtained for the presence of a hydroxypentanone ring, a PG-like structure. The sequence of the protons on the ring carbons was unequivocally deduced from the double resonance experiments. All the data taken together suggested that the RPS's were the stereoisomer of 3-(2-ethyl-5-hydroxy-3-oxo) cyclopentanyl-2-propenal. Presented at the General Meeting of JSSF held in Tokyo University of Fisheries, Tokyo, April 1983.     

Analysis of oxidation states of vanadium in vanadia–titania catalysts by the IR spectra of adsorbed NO

Adsorption of NO on vanadia–titania samples pre-subjected to different reduction treatments has been studied by FTIR spectroscopy. When the NO adsorption is performed at 85 K on oxidized samples, antisymmetric NONO species, typical for V⁵⁺ sites, are detected and characterized by bands at 1779 and 1686 cm⁻¹. At ambient temperature, however, adsorption is negligible and only with time reactive adsorption occurs producing NO⁺ (2120 cm⁻¹), nitro/nitrato species (bands in the 1650–1100 cm⁻¹ region) and weakly adsorbed NO (broad band at 1915 cm⁻¹). Adsorption of NO at ambient temperature on reduced samples results in the formation of two types of species: (i) V⁴⁺(NO)₂ dinitrosyls characterized by ν_s(NO) and ν_as(NO) at 1903–1880 and 1769–1753 cm⁻¹, respectively, and (ii) V³⁺(NO)₂ complexes, which give rise to ν_s(NO) at 1834–1822 cm⁻¹ and ν_as(NO) at 1697–1685 cm⁻¹. At low temperature the dinitrosyls are transformed into species in which more than one (NO)₂ dimer is attached to one cationic site. Addition of O₂ to NO, preadsorbed on reduced vanadia–titania samples, results in a fast oxidation of the V³⁺(NO)₂ species, whereas the V⁴⁺(NO)₂ complexes are more stable and do not disappear completely in the presence of oxygen. The results obtained suggest that NO is a convenient probe molecule for the analysis of the oxidation state of vanadium in vanadia–titania catalysts. To prevent oxidation of reduced vanadium sites, low equilibrium pressures of NO and registration of the IR spectrum soon after the NO admission are recommended. This revised version was published online in August 2006 with corrections to the Cover Date.     

An infrared absorption study of autoxidized methyl linoleate

Summary A study has been made of the infrared absorption spectra of autoxidized methyl linoleate in samples ranging from PV 1 to PV 940 m.e./kg. Principal changes occur in the frequency range 3400–3550 cm⁻¹ where bonded−OH groups absorb and at 1650–1775 cm⁻¹ where >c=0 groups absorb. Two maxima were observed in oxidized samples in the −OH absorption range: one sharp and distinct at 3467–70 cm⁻¹ which increased in intensity with increase in PV and a broad band which increased with increasing PV until it resolved into a true maximum at 3430 cm⁻¹. Reduction of typical oxidized samples with KI reagent resulted in disappearance of the 3430 cm⁻¹ band and appearance of a new band above 3500 cm⁻¹. The band at 3430 cm⁻¹ was attributed to −OOH groups associated by hydrogen bridging. The band at 3467 cm⁻¹ and the band appearing above 3500 cm⁻¹ were attributed to −OH groups, the band at the higher frequency resulting directly from reduction of a hydroperoxide. Absorption due to ketone and aldehyde carbonyl groups appeared only as an indefinite shoulder on the band due to the ester carbonyl. These were resolved by using the intensity of the sample with PV 1 as I_o and that for the oxidized samples as I. A plot of Log I_o/I then revealed three maxima. These indicate the presence of two and possibly three carbonyl containing substances other than the ester carbonyl in autoxidized methyl linoleate. Absorption in the two critical frequency ranges of fractions of autoxidized methyl linoleate eluted from an adsorption column correlate with interpretations made from ultraviolet absorption studies of the same substances. This paper reports research undertaken in cooperation with the Quartermaster Food and Container Institute for the Armed Forces and has been assigned number 211 in the series of papers approved for publication. The views or conclusions contained in this report are those of the authors. They are not to be construed as necessarily reflecting the views or indorsement of the Department of the Army. Presented at the Fall Meeting of the American Oil Chemists’ Society, New York, Nov. 17, 1948.     

A Novel Dinucleating Ligand-Containing Hexabenzimidazoles and Its Dinuclear Zinc Complex Bridged by a Carboxylate Group for the Hydrolysis of 2-Hydroxypropyl-p-nitrophenyl phosphate

A dinuclear zinc(II) complex with the ligand bis{tris[2-(1-methylbenzimidazole-2-yl)ethyl]-methylamine}nitrilotriacetic acid sodium salt, L, was synthesized and characterized. Complex formation of L with Zn²⁺ in aqueous acetone was studied by Zn²⁺ titration using ¹H NMR and UV–vis spectroscopies. Analysis of the titration data indicates the formation of a dizinc complex. The ν_as(COO⁻) and ν_s(COO⁻) stretches were observed at 1572 and 1450 cm⁻¹, respectively. The low separation of the stretches, Δ_exp = 115 cm⁻¹, is an indication of chelating coordination of the carboxylate group between the two zinc(II) ions. The catalytic activity of [LZn₂]³⁺ 1, as a model for phosphatase that catalyze chemical transformation of phosphate ester, in the hydrolysis of the RNA model, 2-hydroxypropyl p-nitrophenyl phosphate, was examined in aqueous acetone buffer solution, pH 7.0–9.5. The mechanism of the catalytic hydrolysis suggests that the rate of acceleration is due to what is called double Lewis acid activation.     

IRS study of ethylene polymerization catalyst SiO2/MAO/zirconocene

Summary Lewis acidic sites (LAS) of silica, modified with TMA and MAO samples differed by TMA content, have been characterized by IR spectroscopy (CO adsorption as probe molecule at 77 K). Two types of LAS were found on the surface of silica modified with MAO and TMA: M LAS of moderate strength (ν_CO= 2204−2212 cm⁻¹) and weak W LAS (ν_CO= 2194 cm⁻¹). The concentration of these acidic sites has been estimated. It was shown by IRS study Cp₂ZrMe₂ interacts both with W LAS and M LAS. Correlation between the amount of M LAS and the activity of ethylene polymerization has been found. Received: 13 October 1998/Revised version: 10 June 1999/Accepted: 10 June 1999     

FTIR study of CO adsorption on coked Pt–Sn/Al2O3 catalysts

Infrared spectra of adsorbed CO have been used as a probe to monitor changes in Pt site character induced by the coking of Pt/Al₂O₃ and Pt–Sn/Al₂O₃ catalysts by heat treatment in heptane/hydrogen. Four distinguishable types of Pt site for the linear adsorption of CO on Pt/Al₂O₃ were poisoned to different extents showing the heterogeneity of the exposed Pt atoms. The lowest coordination Pt atoms (ν(CO) < 2030 cm⁻¹) were unpoisoned whereas the highest coordination sites in large ensembles of Pt atoms (2080 cm⁻¹) were highly poisoned, as were sites of intermediate coordination (2030–2060 cm⁻¹). Sites in smaller two‐dimensional ensembles of Pt atoms (2060–2065 cm⁻¹) were partially poisoned, as were sites for the adsorption of CO in a bridging configuration. The addition of Sn blocked the lowest coordination sites and destroyed large ensembles of Pt by a geometric dilution effect. The poisoning of other sites by coke was impeded by Sn, this effect being magnified for Cl‐containing catalyst. Oxidation or oxychlorination of coked catalyst at 823 K followed by reduction completely removed coke from the catalyst surfaces. This revised version was published online in July 2006 with corrections to the Cover Date.     

Redox and transport behaviors of Cu(I) ions in TMHA-Tf<Subscript>2</Subscript>N ionic liquid solution

The redox and transport behavior of monovalent copper species in an ammonium imide-type ionic liquid, trimethyl-n-hexylammonium bis((trifluoromethyl)sulfonyl)amide (TMHA-Tf₂N) were examined with a micro-disc electrode to clarify its applicability to, for example, electroplating. It was found that the diffusion coefficient of Cu(I) ions in TMHA-Tf₂N containing 12 mmol dm⁻³ Cu(I) ions was 1.2 × 10⁻⁶ cm² s⁻¹ and the redox potential of Cu(I)/Cu was in the potential range 0.1–0.2 V vs. I ⁻/I ₃⁻ at 50 °C. The diffusion coefficient was one order smaller than that of Cu(II) ions in aqueous solution due to the high viscosity of the ionic liquid. The diffusion coefficient of Cu(I) ion increased with rising temperature and was 1.0 × 10⁻⁵ cm² s⁻¹ at 112 °C, which was comparable to that of Cu(II) ions in aqueous CuSO₄ solutions at ambient temperature. This is accounted for by the drastic decrease in the viscosity of the ionic liquid solution with increasing temperature. The activation energy of diffusion was estimated to be 39 kJ mol⁻¹ in the ionic liquid solution.     

Investigation of 12-Tungstophosphoric Acid Supported on Ce0.5Zr0.5O2 Solid Solution

The nature of the Keggin ions of tungstophosphoric acid interacting with Ce_0.5Zr_0.5O₂ solid solution has been investigated. The vibrational study shows additional IR features at 1051 and 957 cm⁻¹ which are correlated to the primary Keggin anions interacting with Lewis sites involving Ce⁴⁺ and Zr⁴⁺ ions, and thus affecting the P–O and W=O_terminal bonds. The IR study indicates the formation of interfacial Ce⁴⁺–O–W and Zr⁴⁺–O–W bonds. The chemisorbed Keggin molecular layers on Ce_0.5Zr_0.5O₂ show activity towards conversion of acetophenone to styrene by Meerwein–Ponndorf–Verley reduction followed by dehydration. The activity is correlated with the relative intensities of IR peaks at 1051 and 957 cm⁻¹ of the perturbed Keggin molecular layers.     

Synthesis and spectroscopic properties of long-chain aza,aziridine and azetidine fatty esters

Reaction of 1-mesyloxynonane with methyl 8-aminooctanoate gives methyl 9-azastearate (I, 20%); treatment of methyl 9(10),10(9)-azidohydroxyoctadecanoate and methyl 10-azido-12-hydroxyoctadecanoate with triphenylphosphine furnishes the corresponding aziridine derivative (II, 75%) and two geometric azetidine isomers (IIIa and IIIb, 37%), respectively. The aza function in compound I, the aziridine nucleus in compound II and the azetidine system in compounds IIIa, IIIb were characterized by¹H nuclear magnetic resonance (NMR) and¹³C NMR spectral analysis. The infrared spectral analyses of compounds (I), (II) and (IIIa,IIIb) showed characteristic absorption bands at 3200–3300 cm⁻¹ for the N-H stretching vibration.     

On the structure of glasses in the Ge-S-Br and Ge-Se-Br systems

The structure of the vitreous GeSBr₂ and GeSeBr₂ compounds has been investigated using Raman scattering spectroscopy. The Raman spectra of the GeSBr₂ compound contain bands at 235 and 113 cm⁻¹, which are attributed to vibrations in the GeBr₄ molecule, and bands at 288, 254, 161, and 147 cm⁻¹, which are absent in the Raman spectra of binary compounds. The Raman spectrum of the GeSeBr₂ glass has common features with the spectra of the GeSe₂ and GeBr₄ compounds but also involves a number of new bands intermediate in position between the bands at 265 cm⁻¹ for the GeSe₂ compound and the bands at 325 cm⁻¹ for the GeBr₄ compound. The spectra obtained confirm the existence of equilibria between the formation and dissociation of ternary structural units in melts of the thiobromide and selenobromide systems.     

Infrared absorption of branched-chain fatty acids and derivatives in the carbon-hydrogen stretching region

Summary An investigation of the lithium fluoride region makes it possible to characterize a number of structural isomers of branched-chain fatty acids. For example, 2-methyl, 3-methyl, and 5-methyl hexanoic acids may be distinguished. Similarly a number of isomers of octanoic acid may be identified ; 2-n-propyl and 2-isopropyl hexanoic acid may be differentiated. The isomers of 2-n-butyl hexanoic acid may also be identified. Absorption bands at 2960 cm⁻¹ and 2930 cm⁻¹ have been assigned, respectively, to asymmetrical methyl stretching modes and in-phase vibrations of the methylene group. Absorption at 2870 cm⁻¹ is associated with symmetrical stretching modes of the methyl group. The absorption at 2860 cm⁻¹ has been assigned to the out-of-phase vibrations of the methylene group. These assignments correspond to those of Fox and Martin and of Pozefsky and Coggeshall. The absorption bands at 2930 cm⁻¹ and 2860 cm⁻¹ are stronger than those at 2960 cm⁻¹ and 2870 cm⁻¹ when the ratio of methylene groups to methyl groups equals or exceeds three to one. The one exception to this rule is the case of 2-methyl hexanoic acid and the corresponding silver salt and di-soap. An interaction between the methyl group in the two-position and the acid group has been proposed as an explanation for this case. As the spectra of the fatty acids and their silver salt and aluminum di-soap derivatives are identical in the carbon-hydrogen region, it is obvious that other derivatives of these acids may be identified by reference to the spectra reported.     

Synthesis of deuterium labeled cholesterol and steroids and their use for metabolic studies

A simple method is described for the preparation of [6,7,7⁻²H₃] sterols and steroids. The synthesis starts with a Δ⁵-sterol or steroid and involves preparation of the 6-oxo-3α,5α-cyclosteroid, base exchange in the presence of deuterium oxide to introduce two deuteriums at the C-7 position and sodium borodeuteride reduction of the 6-oxo group to introduce the third deuterium atom at C-6. Rearrangement of the [6,7,7⁻²H₃]6α-hydroxy-3α,5α-cyclosteroid then gives the desired [6,7,7^-2H₃]-Δ⁵ sterol or steroid. [6,7,7⁻²H₃]Cholesterol, [6,7,7⁻²H₃]pregnenolone and [6,7,7⁻²H₃]3β-hydroxyandrost-5-en-17-one were synthesized in this fashion and [6,7,7⁻²H₃]progesterone was prepared from the [6,7,7⁻²H₃]pregnenolone. Three examples of the use of these deuchromatography-mass spectrometry. The chrysophyte alga,Ochromonas malhamensis, was shown to be capable of introducing an extra methyl or ethyl group at C-24 of the side chain of [6,7,7⁻²H₃]cholesterol to yield brassicasterol and poriferasterol, respectively. The ovary of the echinoderm,Asterias rubens, was demonstrated to metabolize [6,7,7⁻²H₃]progesterone to yield mainly the 5α-isomers of pregnane-3,20-dione and 3β-hydroxypregnan-20-one. However, the 5β-isomers of these compounds were also detected as minor products for the first time as progesterone metabolites in this animal. Isolated oocytes of the frog,Xenopus laevis, produced a number of metabolites of [6,7,7⁻²H₃]progesterone. In this report, two of them were shown to be 17α-hydroxy-pregn-4-en-3,20-dione and 20α-hydroxypregn-4-en-3-one. Presented at the “Sterol Symposium” of the American Oil Chemists' Annual International Conference, New Orleans, LA, May 1981.     

A new conjugated linoleic acid isomer, 7 trans, 9 cis-octadecadienoic acid, in cow milk, cheese, beef and human milk and adipose tissue

The identity of a previously unrecognized conjugated linoleic acid (CLA) isomer, 7 trans, 9 cis-octadecadienoic acid (18∶2) was confirmed in milk, cheese, beef, human milk, and human adipose tissue. The 7 trans, 9 cis-18∶2 isomer was resolved chromatographically as the methyl ester by silver ion-high-performance liquid chromatography (Ag⁺-HPLC); it eluted after the major 9 cis, 11 trans-18∶2 isomer (rumenic acid) in the natural products analyzed. In the biological matrices in-vestigated by Ag⁺-HPLC, the 7 trans, 9 cis-18∶2 peak was generally due to the most abundant minor CLA isomer, ranging in concentration from 3 to 16% of total CLA. By gas chromatography (GC) with long polar capillary columns, the methyl ester of 7 trans, 9 cis-18∶2 was shown to elute near the leading edge of the major 9 cis, 11 trans-18∶2 peak, while the 4,4-dimethyloxazoline (DMOX) derivative permitted partial resolution of these two CLA isomers. The DMOX derivative of this new CLA isomer was analyzed by gas chromatography-electron ionization mass spectrometry (GC-EIMS). The double bond positions were at Δ7 and Δ9 as indicated by the characteristic mass spectral fragment ions at m/z 168, 180, 194, and 206, and their allylic cleavages at m/z 154 and 234. The cis/trans double-bond configuration was established by GC-direct deposition-Fourier transform infrared as evidenced from the doublet at 988 and 949 cm⁻¹ and absorptions at 3020 and 3002 cm⁻¹. The 7 trans, 9 cis-18∶2 configuration was established by GC-EIMS for the DMOX derivative of the natural products examined, and by comparison to a similar product obtained from treatment of a mixture of methyl 8-hydroxy-and 11-hydroxyoctadec-9 cis enoates with BF₃, in methanol. Contribution number S010 from the Food Research Center, Guelph, Ontario, Canada.     

Quantitation of estolides by Fourier transform infrared spectroscopy

Estolides were produced from meadowfoam oil fatty acids, oleic, linoleic, petroselinic, andcis-5,cis-13 docosadienoic acids. Estolide reaction mixtures were quantitated by Fourier transform infrared spectroscopy and compared to the area percentages determined by high-performance liquid chromatography. The absorbance frequency of estolide carbonyl (1737 cm⁻¹) is different than the lactone carbonyl (1790 cm⁻¹) and the acid carbonyl (1712 cm⁻¹). Estolide standards were obtained by wiped-film molecular-still distillations and column chromatography.     

The metabolism of lithocholic acid-3α-sulfate by human intestinal microflora

Lithocholic acid-3α-sulfate is metabolized by human intestinal microflora to nonpolar metabolites which have been partially purified by Sephadex LH-20 chromatography. These metabolites were characterized by thin layer and gas liquid chromatography as well as combined gas liquid chromatography-mass spectrometry. The chromatographic properties of one of the metabolites are consistent with those described for a Δ²-or Δ³. The formation of cholenates by the microflora may represent a retoxification of the sulfate ester of lithocholic acid. The following names and abbreviations for chemicals and methods have been used throughout the text: lithocholic acid (LA)=3α-hydroxy-5β-cholan-24-oic acid; isolithocholic acid (ILA)=3β-hydroxy-5β-cholan-24-oic acid; 3-keto=3-keto-5β-cholan-24-oic acid; 5β=5β-cholan-24-oic acid; Δ²-cholenate; = 5β-chol-2-en-24-oate; Δ³-cholenate =5β-chol-3-en-24-oate LASO₄=lithocholic acid-3α-sulfate; methyl lithocholate (MLA)=methyl-3α-hydroxy-5β-cholan-24-oate; methyl isolithocholate (MIL)=methyl-3β-hydroxy-5β-cholan-24-oate; methyl-3-keto (Me-3-keto)=methyl-3-keto-5β-cholan-24-oate; methyl-5β (Me-5β)=methyl-5β-cholan-24-oate; methyl deoxycholate (MEDOXY)=methyl-3α12α-dihydroxy-5β-cholan-24-oate; GLC=gas liquid chromatography; GLC-MS=gas liquid chromatography-mass spectrometry; GFP=glass fiber paper; ITLC-SG=instant thin layer chromatography-silica gel; ITLC-SA=instant thin layer chromatography-silicic acid; BHI=brain heart infusion; MFC=mixed fecal culture.     

Structure and thermal properties of titanium dioxide-polyacrylate nanocomposites

Summary UV curable, transparent acrylic resin/titania organic–inorganic hybrid films were prepared by controlled hydrolysis of titanium tetrabutoxide (TTB) in Span85/Tweeen80 reverse micelles and subsequent in situ photopolymerization of acrylic monomers. The qualitative content of TiOTi group and TiOH was monitored by FTIR spectrum, and the thermal stability and film surface were characterized by TGA, DSC and AFM, respectively. TGA data show that TiO₂-hybrid films can upgrade the decomposition onset temperature and the temperature at which there is a maximum mass loss rate (T_max). DSC data show that prolonged exposure to UV light and post-thermal treatment can decrease the T_onset and T_peak of the exothermal peak and the condensation temperature between TiOH, and increase ΔH of the exothermal peak. FTIR spectra show the presence of two νs(COO^-) modes with the νa-νs splitting magnitude (Δν∼87 cm^-1 and 148 cm^-1, respectively), suggesting that acrylic acid acts as a bidentate coordination mode and therefore chemical linkages exist between inorganic and organic phases. AFM phase images showed the presence of inorganic domains, with mean size of 21.6 nm–28.8 nm, were uniformly dispersed in the polymeric networks.     

Synthesis and photoconductivities of bisazo charge generation materials

Six bisazo compounds were synthesized by coupling 2-(4′-aminophenyl)-6-aminobenzoxazole as diazo component with N-phenyl-N′-(2-hydroxy-3-naphthoyl)urea derivatives, and characterized by ultra-violet and visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA). Using these bisazo compounds as charge generation materials and CT-191(2-methyl-4-(N,N-dibenzyl) aminobenzoaldehyde-1,1-diphenylhydrazone) as charge transportation material, organic photoconductive devices were prepared. The result from photoconductivity measurement of the devices shows that the bisazo compound from N-(2-methylphenyl)-N′-(2-hydroxy-3-naphthoyl)urea has the best xerographic performance, V ₀=600 V, V _R=30 V, R _d=15 V·s⁻¹, E _1/2=3.5 lx·s. __________ Translated from Journal of Tianjin University, 2007, 40(11): 1295–1299 [译自: 天津大学学报]     

Fumigant and Contact Toxicities of Monoterpenes to <Emphasis Type="Italic">Sitophilus oryzae</Emphasis> (L.) and <Emphasis Type="Italic">Tribolium castaneum</Emphasis> (Herbst) and their Inhibitory Effects on Acetylcholinesterase Activity

A comparative study was conducted to assess the contact and fumigant toxicities of eleven monoterpenes on two important stored products insects—, Sitophilus oryzae, the rice weevil, and Tribolium castaneum, the rust red flour beetle. The monoterpenes included: camphene, (+)-camphor, (−)-carvone, 1-8-cineole, cuminaldehyde, (l)-fenchone, geraniol, (−)-limonene, (−)-linalool, (−)-menthol, and myrcene. The inhibitory effect of these compounds on acetylcholinesterase (AChE) activity also was examined to explore their possible mode(s) of toxic action. Although most of the compounds were toxic to S. oryzae and T. castaneum, their toxicity varied with insect species and with the bioassay test. In contact toxicity assays, (−)-carvone, geraniol, and cuminaldehyde showed the highest toxicity against S. oryzae with LC₅₀ values of 28.17, 28.76, and 42.08 μg/cm², respectively. (−)-Carvone (LC₅₀ = 19.80 μg/cm²) was the most effective compound against T. castaneum, followed by cuminaldehyde (LC₅₀ = 32.59 μg/cm²). In contrast, camphene, (+)-camphor, 1-8-cineole, and myrcene had weak activity against both insects (i.e., LC₅₀ values above 500 μg/cm²). In fumigant toxicity assays, 1-8-cineole was the most effective against S. oryzae and T. castaneum (LC₅₀ = 14.19 and 17.16 mg/l, respectively). Structure-toxicity investigations revealed that (−)-carvone—, a ketone—, had the highest contact toxicity against the both insects. 1-8-Cineole—, an ether—, was the most potent fumigant against both insects. In vitro inhibition studies of AChE from adults of S. oryzae showed that cuminaldehyde most effectively inhibited enzyme activity at the two tested concentrations (0.01 and 0.05 M) followed by 1-8-cineole, (−)-limonene, and (l)-fenchone. 1-8-Cineole was the most potent inhibitor of AChE activity from T. castaneum larvae followed by (−)-carvone and (−)-limonene. The results of the present study indicate that (−)-carvone, 1,8-cineole, cuminaldehyde, (l)-fenchone, and (−)-limonene could be effective biocontrol agents against S. oryzae and T. castaneum.     

Isotopic Oxygen Exchange and EPR Studies of Superoxide Species on the SrF2/La2O3 Catalyst

By using the in situ IR spectroscopy, the superoxide species (O₂⁻), characterized by the O–O stretching peak at 1130 cm⁻¹, was detected on the SrF₂/La₂O₃ catalyst at temperatures up to 973 K. The introduction of ¹⁸O₂ isotope caused the 1130 cm⁻¹ peak to shift to lower wavenumbers (1095 and 1064 cm⁻¹), consistent with the assignment of the spectra to the superoxide species. A good correlation between the rate of the disappearance of the O₂⁻ species and that of the formation of C₂H₄ was observed, suggesting that O₂⁻ was the active oxygen species responsible for the oxidative coupling of methane (OCM) on the SrF₂/La₂O₃ catalyst. This conclusion was reinforced by the EPR experiments (g_xx = 2.0001, g_yy = 2.0045, g_zz = 2.0685), showing that O₂⁻ was the only paramagnetic oxygen species detectable on the O₂-preadsorbed SrF₂/La₂O₃ catalyst. These results suggest that superoxide O₂⁻ can be a stable active oxygen species, whose role in the OCM reaction cannot be overlooked.     

Synthesis of a novel amphiphilic polymer containing nucleobases in the self-organized nanospheres

A simple strategy to achieve molecular recognition in water is to make the polymers self-organized into nanospheres which could incorporate the functional groups containing hydrogen bonding sites into hydrophobic-lipophilic regions. A novel amphiphilic polymer, Poly(polyoxyethylene-600)-oxy-5-(6-(1-thymine)hexyl)) isophthaloyl (PPETHI), has been synthesized. The PPETHI polymer could self-organize into nanospheres in dilute aqueous solution, which were 150–300 nm in diameter as estimated by SEM. The isophthaloyl with side hexyl thymine of the polymer self-organized into hydrophobic regions and the PEG surrounded it. Molecular recognition between thymine in PPETHI polymer and adenine substrate has been studied by FT-IR. The FT-IR studies demonstrate that C₄=O of thymine has recognized with N-H of adenine through complementary nucleobases. It shows that the typical characteristic band at 3,352 cm⁻¹ of N-H stretching vibration of adenine shifted to 3,373 cm⁻¹ and the band at 1,685 cm⁻¹ of C₄=O of thymine shifted to 1,680 cm⁻¹. To confirm the formation of hydrogen bonds, the N-H band at 3,373 cm⁻¹ and C₄=O band at 1,680 cm⁻¹ have retrieved to 3,312 cm⁻¹ and 1,685 cm⁻¹ respectively upon heating to 115 °C or higher by means of variable temperature FT-IR. The formations of hydrogen-bonds between thymine in the polymer and adenine substrate in nanospheres were confirmed. It could enhance their interaction and loading capacity.