Condensation reactions of phenolic resins VII: catalytic effect of sodium bicarbonate for the condensation of hydroxymethylphenols

This article describes the catalytic effect of NaHCO₃ on condensation reactions of monomeric hydroxymethylphenols (HMPs) to elucidate the cure-acceleration mechanism. By comparison of the kinetics of self-condensations of HMPs, NaHCO₃ was proved to increase the reactivity of para-hydroxymethyl groups. The changes of ¹³C nuclear magnetic resonance (NMR) chemical shifts on each HMP system with the additive indicated that the addition of NaHCO₃ enhanced some molecular interactions between HMPs and NaHCO₃, facilitating a resonance effect that might play a similar role in dissociation of the phenolic hydroxyl groups of HMPs. In addition, computational modeling by molecular orbital calculations elucidated that hydrogen carbonate anion (HCO ₃ ⁻ ) forms an interaction between either the para-hydroxymethyl group and the phenolic hydroxyl group or between the two para-hydroxymethyl groups of HMPs by hydrogen bonds. From the experimental results, the authors proposed the mechanism of the catalytic action of NaHCO₃: it appears to be due to the delocalization of an electron initiated by the interaction of the para-hydroxymethyl groups and the phenolic hydroxyl of HMPs with HCO ₃ ⁻ through hydrogen bonds, which results in facilitating the formation of active species.     

Revisiting the mechanism of <Emphasis Type="Italic">β-O</Emphasis>-4 bond cleavage during acidolysis of lignin IV: dependence of acidolysis reaction on the type of acid

The dependence of the acidolysis reaction of a C₆-C₃ dimeric nonphenolic β-O-4 type lignin model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl) propane-1,3-diol (veratrylglycerol-β-guaiacyl ether, VG), on the type of acid applied was examined using three different acids [0.2 mol/l HCl, 0.2 mol/l HBr, and 0.1 mol/l (0.2 N) H₂SO₄ in 82% aqueous 1,4-dioxane at 85°C]. In the HCl system, the major reaction modes of the corresponding benzyl cation-type intermediate (BC), which is produced by protonation of the α-hydroxyl group of VG and successive release of the water molecule, are the abstraction of the β-proton and hydride transfer from the β-to the α-position. The liberation of formaldehyde from the γ-hydroxymethyl group of BC is the predominant reaction mode in the H₂SO₄ system. Apparently, an unknown reaction mode or modes is operative in the early stage of the HBr system that causes rapid disappearance of VG accompanied by the quantitative formation of 2-methoxyphenol without affording the common counterpart of a Hibbert’s ketone, 1-hydroxy-3-(3,4-dimethoxyphenyl) propan-2-one. The reaction mode in the HBr system changes with the progress of the reaction and is the same as that in the HCl system after the early stage.     

Improvement of softening treatment technology of bamboo

In order to improve the efficiency of softening bamboo block when manufacturing bamboo veneer, chemistry reagents such as NaHCO₃ are often adopted during bamboo softening treatment. But the results of Fourier transform infrared spectroscopy (FTIR) showed that the band intensity at 1,733 cm⁻¹, assigned to C=O stretching vibration in xylan, was reduced in the spectrum of softening-treated bamboo with NaHCO₃ compared with that of not softening-treated bamboo and softening treatment of bamboo without NaHCO₃. That is to say, that the hemicellulose of bamboo was destroyed after softening treatment with NaHCO₃, which meant that softening treatment of bamboo with NaHCO₃, is not a perfect softening treatment method. Thus, in this paper a softening technology at 120°C for 30 min in a closed container was adopted. The results of FTIR show that there was almost no difference in FTIR spectra between no softening treatment of bamboo and softening treatment of bamboo at 120°C for 30 min, which meant that softening treatment at 120°C for 30 min had no effect on the composition of bamboo. The results of dynamic mechanical analysis (DMA) show that T _g of not softening-treated bamboo was 120°C, while T _g of softening-treated bamboo at 120°C for 30 min was 88°C. T _g of softening-treated bamboo at 120°C for 30 min decreased by 26.7% compared with that of not softening-treated bamboo. The results of hardness show that the hardness of bamboo strip after a softening treatment for 30 min at 120°C decreased by 42.0–54.6% compared with that of not softening-treated bamboo. The results of hardness and DMA show that the effect of softening treatment of bamboo at 120°C for 30 min was resultful.     

Coniferyl aldehyde dimers in dehydrogenative polymerization: model of abnormal lignin formation in cinnamyl alcohol dehydrogenase-deficient plants

The enzymatically dehydrogenative polymerization of coniferyl aldehyde and coniferyl alcohol was studied to understand lignins in cinnamyl alcohol dehydrogenase (CAD)-downregulated plants. The sample dimers were prepared by polymerization under three reaction systems (coniferyl alcohol, coniferyl aldehyde, and their combination) with horseradish peroxidase/H₂O₂ under the conditions of limited reaction time. In addition, the residual amount of substrate in each reaction was determined at specified time intervals. In the reaction system of coniferyl aldehyde, the 5-5-type dimer was formed in preference to- and-5 dimers; in the reaction system of coniferyl alcohol the-5 dimer was preferentially formed. Furthermore, it was revealed when quantifying dimers among reaction systems that the total dimer formation capability of coniferyl alcohol clearly surpassed that of coniferyl aldehyde. However, the dimers cross-coupled with coniferyl alcohol and coniferyl aldehyde were formed in amounts not accounted for by the difference seen in dimer formation abilities with the two substrates.Part of this paper was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

Effects of side-chain hydroxyl groups on pyrolytic <Emphasis Type="Italic">β</Emphasis>-ether cleavage of phenolic lignin model dimer

Effects of side chain hydroxyl groups on pyrolytic β-ether cleavage of phenolic model dimers were studied with various deoxygenated dimers under pyrolysis conditions of N₂/400°C/1 min. Although phenolic dimer with hydroxyl groups at the C _α ⁻ and C _γ ⁻positions was much more reactive than the corresponding nonphenolic type, deoxygenation at the C _γ -position substantially reduced the reactivity up to the level of the nonphenolic type. These results are discussed with the cleavage mechanism via quinone methide intermediate formation, which is activated through intramolecular hydrogen bonds between C _α ⁻ and C _γ ⁻ hydroxyl groups.     

Changes in soil P chemistry as affected by conversion of natural secondary forests to larch plantations

To assess the impact of conversion of native forests to monocultural larch plantations on soil chemical properties, we compared the total and various fractions of soil phosphorus (P) and acid phosphatase activity (APA) between natural secondary forests (NSF) and Larix olgensis plantations (LOP) on a montane forest site in eastern Liaoning Province, Northeast China. We found that the concentrations of total P (TP), inorganic P, and iron-bound P (Fe-P) were significantly higher, and the concentrations of microbial biomass P (MBP), sodium bicarbonate-extractable organic P (NaHCO₃-Po), and APA were significantly lower, in the LOP stands than in the NSF stands; whilst organic P, sodium bicarbonate-extractable inorganic P (NaHCO₃-Pi), aluminum-bound P (Al-P) and calcium-bound P (Ca-P) were comparable between the two forest types. Our study also showed that the ratios of MBP/TP, NaHCO₃-Pi/TP, NaHCO₃-Po/TP, and APA significantly varied with time during the growing season. Moreover, the concentrations of NaHCO₃-Pi, NaHCO₃-Po, and MBP had significant (P < 0.01) and positive linear relationships with APA. Overall, results from this study suggest that conversion of native forests to larch plantations in the region is more likely to cause compositional change in soil P than to result in reduction in overall P availability.     

Study of hydration behavior of wood cement-based composite II: effect of chemical additives on the hydration characteristics and strengths of wood-cement composites

The influence of the 30 chemical additives on the hydration characteristics of birch wood-cement-water mixture was determined by measuring the maximum hydration temperature (T _max) and the time (t _max) required to reach the temperature. The chemical additives were tested and divided into two types depending on the pattern of exothermic reaction peak within the 24-h observation period. The wood-cement-water mixtures with additions of each of the 11 type I chemical additives showed a two-peak temperature-time curve similar to that for neat cement. CaCl₂, FeCl₃, and SnCl₂ reached the highestT _max above 50°C. When the 19 type II chemical additives were included, the mixtures offered only one peak hydration temperature-time curve. Among them, the 10 chemical additives caused an obvious temperature increase at the beginning of the hydration reaction. The most significant effect was with the addition of diethanolamine, where the mixture produced aT _max above 50°C. The strength values (modulus of rupture, internal bond strength) of word-cement board were tested with separate additions of the 10 chemical additives arranged by the highestT _max. There was a good positive correlation betweenT _max and the strength values. In addition, the composite chemical additives were preliminarily examined to determine if they accelerated the hydration reaction of blast-furnace slag cement. The results revealed that composite chemical additives evidently accelerated the hydration reaction and the setting of blast-furnace slag cement mixed with wood. Blast-furnace slag cement can thus be considered for use as an acceptable inorganic bonding material for wood-cement panel manufacture.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

Condensation reactions of phenolic resins IV: self-condensation of 2,4-dihydroxymethylphenol and 2,4,6-trihydroxymethylphenol (2)

Kinetics of the self-condensation of 2,4-dihydroxymethylphenol (2,4-DHMP) and 2,4,6-trihydroxymethylphenol (THMP) were investigated to elucidate the mechanisms of the condensation of hydroxymethylphenols (HMPs). Rate equations were derived on the assumptions of the formation of quinone methide intermediates as unimolecular reactions and the occurrence of bimolecular reactions between undissociated HMPs, between undissociated HMP and dissociated HMP, and between dissociated HMPs. Rate constants were determined numerically by comparing the calculated reaction rates with observed ones. The results of analyses are as follows: (1) Both unimolecular and bimolecular reactions occur as the rate-determining steps during the self-condensation of 2,4-DHMP and THMP with low concentrations. (2) Nothing but bimolecular reactions occur as the rate-determining steps during the self-condensation of THMP with high concentrations. (3) Differences in the activation energy and the reaction rate due to the unimolecular process between 2,4-DHMP and THMP are small. (4) Rates of bimolecular reactions of THMP are about five times as large as those of 2,4-DHMP. (5) The values of the rate constants and the activation energy for the bimolecular reactions of THMP of low concentrations differ from those of THMP of high concentrations, indicating the difference in reaction mechanisms.     

Assessing toxicity of post-emergence herbicides to the Spilarctia obliqua Walker (Lepidoptera: Arctiidae)

The lethal and sublethal effects of three post-emergence herbicides, 2,4-D ethyl ester (Weedkill 80WP), imazethapyr (Pursuit 10EC) and quizalofop ethyl (Tergasuper 5EC) fortified with artificial diets were studied on larvae of Spilarctia obliqua Walker (Lepidoptera: Arctiidae). Quizalofop ethyl and imazethapyr caused significant reduction of pest survival at almost all levels; however, 2,4-D ethyl ester was nontoxic. Interestingly, LC₅₀ data (0.230 and 0.855% for quizalofop ethyl and imazethapyr, respectively) obtained from probit analysis were almost equal to labeled doses (x) of quizalofop ethyl (x = 0.16%) and imazethapyr (x = 0.625%), which shows the high toxicity of these compounds against S. obliqua larvae. Among the three herbicides, imazethapyr caused sublethal effects on this pest, increasing the larval period at almost all concentrations tested in the artificial diet. Considering the markedly significant effect of quizalofop ethyl on pest survivorship with no sublethal effect, we suggest incorporating it into the integrated pest management module for S. obliqua in legumes or oilseed crops with other biorational insecticides. Based on toxicity, imazethapyr can be a potential candidate for integrated management of S. obliqua. However, because of its sublethal effects, we advocate caution while using it in the presence of pest infestations.     

Phosphorus pools in Oxisols under shaded and unshaded coffee systems on farmers' fields in Brazil

Phosphorus (P) is a primary limiting nutrient for crop production in weathered tropical soils. The deficiency is mainly caused by sorption of phosphate onto Al- and Fe- (hydr)oxides. We hypothesise that the distribution of soil P among various pools is influenced by land use. Our objective was to characterise the soil inorganic (Pi) and organic P (Po) pools and to compare the various pools at different depths in agroforestry (shaded) and monocultural (unshaded) coffee cultivation systems. The study was carried out in the Atlantic Coastal Rainforest domain, Brazil, with Oxisols as the dominant soil type. Soils were collected from four farmers' coffee (Coffea arabica L.) fields, two agroforestry and two monocultural systems. Three profiles were sampled per field, at depths of 2–3, 10–15 and 40–60 cm. A simplified sequential P fractionation was carried out, using resin, 0.5 M NaHCO₃, 0.1 M NaOH, 1 M HCl and concentrated HCl as extractants. Sum-P (resin, NaHCO₃ NaOH, 1 M HCl and concentrated HCl) ranged from 370 to 830 mg kg^–1. Concentrated HCl extracted the largest portion (74%), followed by NaOH (22.5%). Labile (sum of resin, NaHCO₃ and NaOH) P ranged from 13 to 40% of Sum-P. The major part (62%) of the labile fraction was Po. In the agroforestry fields, the amount of Po decreased less with depth and the percentage of Po in labile pools was higher than in monocultural fields. This suggests that agroforestry maintains larger fractions of P available to agricultural crops by influencing the dynamics of P through the conversion of part of the Pi into Po, thereby reducing P losses to the unavailable pools.This revised version was published online in November 2005 with corrections to the Cover Date.     

Reactivity of green tea catechins with formaldehyde

In the reaction of green tea catechins with formaldehyde at room temperature (25°C), tea catechins were found to have reactivity. In particular, (-)-epicatechin gallate and (-)-epigallocatechin gallate, which have a galloyl moiety at the C-3 position, showed higher reactivity than (+)-catechin, (-)-epicatechin, or (-)-epigallocatechin. Reactivity of various kinds of simple phenolic compounds and flavonoids with formaldehyde was also examined. Among these compounds, only phloroglucinol showed reactivity to the same degree as that of nongalloylated catechins. These results suggest that factors for reactivity with formaldehyde at room temperature may be the presence of a phloroglucinolic A-ring structure and the absence of the electron-attractive group such as a carbonyl group in Cring. The comparison of the reactivity of 3-O-acylated catechins with that of 3-O-galloylated catechins indicated that only a galloyl group effectively enhanced reactivity with formaldehyde.     

Electropolymerization of coniferyl alcohol

Electropolymerization of coniferyl alcohol was carried out in an aqueous system (0.2 M NaOH) and in an organic solvent system [CH₂Cl₂/methanol (4:1 v/v) in the presence of 0.2 M LiClO₄] to produce a dehydrogenation polymer (DHP) - artificial lignin. In both systems, the polymerization of coniferyl alcohol was visually confi rmed. In the aqueous system, no dimer was detected in the reaction medium after electropolymerization, suggesting that endwise polymerization occurred on the electrode surface. Thioacidolysis degradation revealed that the obtained polymers had numerous 8-O-4′ linkages. The electropolymerization products obtained in the organic solvent system also had numerous 8-O-4′ linkages; in particular, the polymers obtained in the initial polymerization stage. This was probably because of the limited area available for reaction and the orientation of coniferyl alcohol on the electrode surface controlled the polymerization.     

Effect of salt stress on activity of superoxide dismutase （SOD） in Ulmus pumila L.

The injury tolerance of cell plasma membrane and the correlative enzymes activities of plasma-membrane protection system in the Ulmuspumila leaves treated by nine concentrations （0.3%, 0.6%, 0,9%, 1,2%, 1.5%, 1.8%, 2,1%, 2.4%, 3.0%） of Na2CO3 and NaHCO3 mixtures were studied in a greenhouse of Northeast Forestry University, Harbin, China. The rate of electrolyte leakage （REL） and SOD （Superoxide dismutase） activity in leaves of different samples were determined. Results showed that the REL in leaves of U. pumila presented a slowly increasing trend at the salt concentrations less than 1.5%, which indicated that cell plasma membrane of U. pumila leaves had rather strong resistance to the injury of salt ion, and had a significant increase at the salt concentrations more than 1.5%. The SOD activities in leaves of U, pumila presented an increased trend at salt concentrations less than 1.5%, the growth of seedlings did not decline, and tress and leaves had no symptom of injury, while the salt concentrations exceeded 1.5%, SOD activities sharply decreased and REL increased promptly.     

二甲基—1,6—辛二烯的环化水合反应研究

３，７－二甲基－１，６－辛二烯（１）在固体酸（分子筛，离子膜和离子交换树脂）作用下与甲酸发生环化水合反应，生成１－（３，３－二甲基环己基）乙醇甲酸酯（４ａ）和３，７，７－三甲基环庚醇甲酸酯（５ａ）的混合物，经皂化反应得到相应的醇（４ｂ和５ｂ）。５，７－二甲基－１，６－辛二烯（２）在同样条件下发生类似的反应，生成３，３，５－三甲基环庚醇甲酸酯（６ａ）经皂化生成３，３，５－三甲基环庚醇（６ｂ）。     

Ethanol production with <Emphasis Type="Italic">β</Emphasis>-xylosidase,xylose isomerase,and <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> from the hydrolysate of Japanese beech after hot-compressed water treatment

Ethanol was produced from the hydrolysate collected as the water-soluble (WS) portion after hot-compressed water (HCW) treatment of Japanese beech. The process involved saccharification with β-xylosidase followed by isomerization with xylose isomerase and fermentation with Saccharomyces cerevisiae. Several process schemes were compared to investigate the effect of process integration of saccharification, isomerization, and fermentation. Higher ethanol yields were obtained for the processes that integrated isomerization and fermentation or saccharification and isomerization. Integration of isomerization and fermentation was effective in converting xylose into ethanol. Similarly, integration of saccharification and isomerization was effective in converting xylooligosaccharides into xylulose. It is presumed that the saccharification reaction toward xylose and the isomerization reaction toward xylulose were linked and therefore each reaction was enhanced.     

Synthesis of dihydroxyphenacyl glycosides for biological and medicinal study: β-oxoacteoside from Paulownia tomentosa

The protected structure of -oxoacteoside (tomentoside A), 2-oxo-2-(3,4-dihydroxyphenyl)ethyl 3-O-(2,3,4-tri-O-acetyl--l-rhamnopyranosyl)-4-O-caffeoyl--d-glucopyranoside 14 was synthesized in 14% overall yield in 11 steps, starting from d-glucose for biological and medicinal studies of phenylpropanoid glycosides. The first step was the preparation of a 3-O-rhamnopyranosyl disaccharide sugar core 2 from a suitably protected rhamnosyl trichloroacetimidate 10 and glucose derivative (diacetone-d-glucose 1) in 71% yield. To the glucose moiety of this sugar core, several protection/deprotection procedures were performed sequentially to obtain a fully acetylated sugar core 7 with a 4-OH group on the glucose moiety, in 57% yield in five steps. Thereafter, to the 4-OH group of the glucose moiety, selective 4-O-caffeoylation was achieved by proton-transfer esterification with 3,4-di-O-allylcaffeic acid 16 to give the caffeoyl disaccharide 11 in 97% yield. Then, it was converted to trichloroacetimidate 13 for a glycosylation donor in 90% in two steps. Finally, anomeric glycosylation was conducted with 2-oxo-2-(3,4-di-allyloxyphenyl)ethyl alcohol 19 with catalytic amounts of BF₃·Et₂O to give 2-oxo-2-(3,4-di-allyloxyphenyl)ethyl 2,6-di-O-acetyl-3-O-(2,3,4-tri-O-acetyl--l-rhamnopyranosyl)-4-O-(3,4-di-allyloxycaffeoyl)--d-glucopyranoside 14 in 60% yield. Deprotected intermediates of compounds 2, 11, 14, and 19 which were obtained in high yield would be useful for biological and medicinal studies of phenylpropanoid glycosides.Part of this study was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April, 2002     

Inhibition of flower bud formation inBetula platyphylla andBetula pendula by gibberellin (GA3) application

Birch (Betula) trees produce a large amount of pollen, which is a cause of serious pollinosis. To control the pollen scattering, we examined the inhibitory effect of gibberellin (GA₃) on flower bud formation of birch. Field-grown trees ofBetula pendula, nine years of age, were treated with a foliar spray of GA₃ (1, 10, and 100 mg L⁻¹),Betula platyphylla trees, 17–23 years of age, were treated with a stem injection of GA₃ (5, 50, and 500 mg per plant) in June or July, 1998. Male flower buds were not observed at the top of new shoots in June, but were observed in July. The number of inflorescence that emerged from randomly sampled branches was counted the next spring. The foliar spray of GA₃ in June at the dose of 10 or 100 mg L⁻¹ decreased the number of inflorescence. Stem injection in June at a dose higher than 50 mg per plant completely inhibited flower bud formation, although it increased bud mortality in some trees. The most effective dose of GA₃ for stem injection to inhibit flower bud formation was between 0.04 and 0.44 mg per cm² of stem cross-section area at breast height. These results indicate that GA₃ applied during the period of floral differentiation markedly inhibits flower bud formation in birch.     

Reactivity of a condensed–type lignin model compound in the Mannich reaction and preparation of cationic surfactant from sulfuric acid lignin

 The chemical conversion of phenolized sulfuric acid lignin (P-SAL), prepared from sulfuric acid lignin (SAL) by phenolation with sulfuric acid catalyst, to novel cationic surfactant was investigated. To elucidate the chemical reactivity of the P-SAL to a Mannich reaction, 1-guaiacyl-1-p-hydroxyphenylethane (I) as a simple phenolized sulfuric acid lignin model compound was reacted with dimethylamine and formaldehyde. Quantitative analysis of the products by gas-liquid chromatography suggested that the p-hydroxyphenyl nucleus was more reactive than the guaiacyl nucleus. The Mannich reaction of SAL with dimethylamine did not yield a soluble cationic surfactant, but P-SAL produced water-soluble cationic surfactant in a quantitative yield. The Mannich reaction products (MP-SAL) of P-SAL had 1,3-dimethylaminomethyl groups/C₉-C₆. The results of the surface tension measurements showed that the decrease in surface tension of MP-SAL was much larger than that of lignosulfonate as a commercial surfactant from lignin.     

Substituent effects of 3,5-disubstituted p-coumaryl alcohols on their oxidation using horseradish peroxidase–H2O2 as the oxidant

The consumption rates of three monolignols (p-coumaryl, coniferyl, and sinapyl alcohols) and eight analogues using horseradish peroxidase (HRP)–H₂O₂ as an oxidant were measured and compared with the anodic peak potentials thereof measured with cyclic voltammetry. 3-Monosubstituted p-coumaryl alcohols, i.e., 3-methoxy-, 3-ethoxy-, 3-n-propoxy-, and 3-n-butoxy-p-coumaryl alcohols, had faster reaction rates than p-coumaryl alcohol. This is most probably due to the electron-donating effect of alkoxyl groups. However, the reaction rates gradually decreased with an increase in the molecular weight of the alkoxyl groups. Furthermore, t-butoxyl group, which is a very bulky substituent, caused an extreme reduction in the reaction rate, even though its electron-donating effect was almost the same as that of other alkoxyl groups. The reaction rates of 3,5-disubstituted p-coumaryl alcohols, especially 3,5-dimethyl-p-coumaryl alcohol, were very low compared with 3-monosubstituted p-coumaryl alcohols. These results suggest that there are three main factors of hindrance during the approach of monolignols to the active site of HRP. First, from the results of 3-monoalkoxy-p-coumaryl alcohols, it was suggested that the volume of substituents could decrease their oxidation rates. Second, from the results of 3,5-disubstituted p-coumaryl alcohols, it was suggested that local steric hindrance by the amino residues quite near the heme decreased the oxidation rates. Third, from the results of the substrates with hydrophobic substituents at their 3,5-positions, we suggested that hydrophilicity near heme would decrease their oxidation rates.     

Effect of pressure on organic acid production from Japanese beech treated in supercritical water

The effect of pressure as described by density was studied on organic acid production from Japanese beech (Fagus crenata) treated in supercritical water. At a reaction temperature of 380°C, the maximum yield of organic acids was 35% at a pressure of 30 MPa (density of water: 0.53 g/ml) for 1 min in a batch-type system. Furthermore, the yield of organic acids decreased with increasing reaction pressure. It was also found that fragmented products from sugars such as methylglyoxal and glycolaldehyde could be more easily converted to organic acids than dehydrated products such as furfural and 5-hydroxymethyl furfural. This result suggests that organic acids can be mainly derived from fragmented products. Part of this article was presented at the 55th Annual Meeting of the Japan Wood Research Society (2005), and at the 17th Annual Meeting of Japan Institute of Energy (2007)