bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoreactions of 3,4,5,6-Tetrafluoro-N-methylphthalimide with Alkenes. Effect of Fluoro Substituents on Photoreaction Pathway
Authors: Kubo Yasuo , Umehara Tomoka 
Published: August 2006

Abstract
Photoreactions of 3,4,5,6-tetrafluoro-N-methylphthalimide (7) with styrene (8), α-methylstyrene (2), and 1,1-diphenylethylene (11) have been investigated in order to clarify the effect of fluoro substituents on the reaction pathway. The irradiation of 7 with 2, 8, and 11 in benzene under N2 gave oxetanes as exclusive products. The irradiation of 7 with 11 under O2 afforded benzophenone (13) together with the oxetane. The methanol-incorporated addition of 2 and 8 to 7 proceeded in photoreactions of 7 with 2 and 8 in methanol. A consideration of the energy levels of the excited triplet states of 7 and the alkenes, the quenching of the fluorescence of 7 by 8, and the concentration effects of the alkenes indicate that all of the reactions occur from the singlet excited state of 7. The difference between the exclusive oxetane formation of 7 and the preferred insertion of alkenes into the C–N bond of phthalimides is discussed regarding the nature of the singlet excited states of the imides. The methanol-incorporated addition and formation of 13 are rationalized in terms of mechanisms involving electron-transfer. The calculated ΔGet values associated with electron-transfer support the electron-transfer process.
Interaction between Copper Chlorophyllin and Poly(vinyl alcohol)
Authors: Enmanji Koe 
Published: August 2006

Abstract
The difference spectrum between copper chlorophyllin (Cu-chln) plus poly(vinyl alcohol) (PVA) and Cu-chln alone exhibits a maximum at 652 nm in water. The Benesi-Hildebrand plots give equilibrium constants of 833 mol−1 dm3 for UMR-20H (degree of saponification: 81.7%) and 1820 mol−1 dm3 for UMR-20M (degree of saponification: 63.8%). The Scatchard plot of these data shows the existence of a cooperative binding.
A Convenient Synthesis of Amides with 2-Halo-2,3-dihydro-1,3,4,2-oxadiazaphospholes as New Condensing Agents
Authors: Kimura Hiroshi , Konno Hidetoshi , Takahashi Naomichi 
Published: August 2006

Abstract
Various amides, including some with bulky substituents, are prepared in good yields from free carboxylic acids and amines under mild conditions by a one-step method using new condensing agents 2-halo-2,3-dihydro-1,3,4,2-oxadiazaphospholes, especially 5-methyl-2-chloro-3-phenyl-2,3-dihydro-1,3,4,2-oxadiazaphosphole.
Steric Effects in Photochemical Cycloadditions of 9-Phenanthrenecarboxylates
Authors: Itoh Hiroki , Shibata Hirofumi , Wagatsuma Marie , Nanjoh Mari , Senda Yasuhisa , Sakuragi Hirochika , Tokumaru Katsumi 
Published: August 2006

Abstract
Efficiency of photochemical intramolecular and intermolecular cycloaddition of 9-phenanthrenecarboxylate-anethole systems is dependent on the structure of anethole moiety. Reduction in reactivity of the anethole moiety by steric effects is explained in terms of decrease in coefficients of frontier orbitals on the double bond due to twisting of the anisyl moiety.
Correlation of Vibrational Zero-Point Energy Shifts of Hydrides upon H/D Isotope Substitutions with Electronegativity
Authors: Oi Takao , Ishida Takanobu 
Published: August 2006

Abstract
Correlation of the contribution of the stretching motion (δ(ZPE)str) to the zero-point energy shift upon H/D mono isotope substitution in HnA (n = 1—4) type hydrides with the electronegativity (χ) of the –Hn−1A moiety was investigated. It is possible to represent all the δ(ZPE)str-χ data by a single crude linear line. The line, however, is too crude to make precise estimation of the δ(ZPE)str value of a hydride from the χ value or to make precise estimation of the χ value from the δ(ZPE)str value. Much more accurate linear relation between δ(ZPE)str and χ can be obtained for each of HA, H2A, H3A, and H4A groups.
Picosecond LIF Studies on the Base-Catalyzed Proton-Transfer Reactions of Some Aminopyridines in Aqueous Solutions
Authors: Fujimoto Akira , Ando Hiroshi , Inuzuka Kozo , Nakamura Junko 
Published: August 2006

Abstract
Fluorescence quenching phenomena for systems of 2-aminopyridine (2-AP), 2,6-diaminopyridine (2,6-DAP), and 3,4-diaminopyridine (3,4-DAP) with sodium hydroxide in aqueous solutions were investigated by means of picosecond laser-induced fluorescence time-profile measurements. A comparison with the steady state fluorescence spectra of these systems showed that the former two amino compounds are successively catalyzed with sodium hydroxide in the excited state to form hydrogen-bonded exciplexes and anions, while 3,4-DAP showed normal fluorescence. The relations among the reaction rate constants for three aminopyridines are discussed.
Preparation and Metal Extraction Behavior of Macrocyclic Complexing Agent Bearing Trifluoromethanesulfonamide Deprotonating Groups
Authors: Kido Hirotsugu , Maeda Mizuo , Takagi Makoto 
Published: August 2006

Abstract
A diaza-18-crown-6 derivative bearing two trifluoromethanesulfonamide groups on N,N′-sites (1(H2L)) extracted divalent metal ions (M2+: Hg, Cu, Pb, Ca, Sr, Ba) into dichloromethane according to the reaction, M2+(aq) + H2L(org) ML(org) + 2H+(aq), Kex = [ML][H+]2/[H2L][M2+]. The magnitude of Kex values followed the order Hg &gt; Pb &gt; Cu &gt;&gt; Sr &gt; Ca &gt; Ba. This paralleled the selectivity obtained with the corresponding phenolic reagent, but the affinity to “soft” metal ions was enhanced for 1, reflecting the N,N,N−,N−-coordinating nature of 1. Moreover, 1 formed a 1 : 2 complex with Cu(II) by the reaction, M2+(aq) + 2H2L(org) M(HL)2(org) + 2H+(aq). This suggests that the 1 : 1 complex of Cu(II) was sterically hindered due to the coordination by the bulky sulfonamido groups.
ESR Spin-Trapping Study of Active Oxygen Radicals from Photoexcited Semiconductors in Aqueous H2O2 Solutions
Authors: Noda Hiroyuki , Oikawa Kazuo , Kamada Hitoshi 
Published: August 2006

Abstract
Experiments were carried out concerning the relation between the production of active oxygen radicals from three semiconductors [TiO2 (anatase and rutile) and WO3] and the concentration of H2O2 by the ESR spin-trapping technique using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trap. Two natures of hydroxyl radicals were produced from photoexcited semiconductors in aqueous H2O2 solutions. These originated in the reduction of H2O2 and the oxidation of water, which were confirmed using 17O-labeled water. The mechanism for the generation of active oxygen radicals is discussed regarding the energy band structures of the semiconductors, the redox potentials of the oxygen radicals, and the surface acidity and basicity of semiconductors.
Unusual Mesogenic Behavior of Laterally Di- and Tri-Substituted Schiff Bases
Authors: Gupta Renu , Vora R A 
Published: August 2006

Abstract
Three homologous Schiff base series, with basic skeleton of N-[4-(4′-n-alkoxybenzoyloxy)-3-methoxybenzylidene]aniline have been synthesized. The position and nature of the substitutent on the aniline moiety have been changed to find out their effects on the mesomorphism. Series I, with a 3-chloro substitutent do not exhibit mesomorphism. Series II, with a 2-methyl substituent in the aniline moiety exhibit monotropic smectic phase from the middle members of the series. However, Series III, having 5-chloro-2-methyl substituents behave like a normal nematogenic series.
The Effect of Solvent on the Synthesis of Pyridazinones and Some Reactions of the New Compounds
Authors: Sayed Galal Hosni , Radwan Azza , Hamed Ashraf Ahmed , Boraie Waleed El-Sayed 
Published: August 2006

Abstract
The reaction of 4-aryl-4-oxo-2-(5-oxo-1,3-diphenyl-2-pyrazolin-4-yl) butanoic acids with hydrazine hydrate in ethanol afforded the 4-(5-oxo-2-pyrazolin-4-yl)-3(2H)-pyridazinones and in 1-butanol a pyrazolo[3,4-c]pyridazino[4,3-e]pyridazine derivative was obtained while in acetic acid the 6-aryl-3(2H)-pyridazinone was the product. Probable mechanism has been proposed. The behavior of the 4-(5-oxo-2-pyrazolin-4-yl)-3(2H)-pyridazinones towards dimethyl sulfate, diethyl sulfate, ethyl bromoacetate, p-anisaldehyde, phosphoryl chloride and phosphorus pentasulfide has been studied.
The Estimation of the β-Sheet-Structure Stability of Protected Peptides in Organic Solvents
Authors: Narita Mitsuaki , Lee Jin-Shik , Hayashi Shizue , Hitomi Mitsuo 
Published: August 2006

Abstract
The β-sheet-structure stability in organic solvents was examined for protected tri- to heptapeptide fragments of E. coli ribosomal protein L7/L12. This was evaluated by monitoring the peptide IR absorption band around 1630 cm−1, assigned to a β-sheet structure, in CH2Cl2 alone or CH2Cl2 containing various concentrations of DMSO. For each peptide with a chain length up to a heptapeptide, the &lt;SPβ&gt; values, defined in a previous paper, of a protected peptide were in harmony with their β-sheet-structure stability almost regardless of their amino acid sequences. This fact indicates that the &lt;SPβ&gt; value is useful for the estimation of the β-sheet-structure stability of protected peptides in organic solvents. It also supports the assumption that the β-sheet-structure stability of protected peptides is strongly dependent on their amino acid compositions and weakly dependent on their amino acid sequences. Furthermore, it was shown that the &lt;SPβ&gt; value of a protected peptide can provide a basis for the choice of reaction solvent. The significance of the present study in the design of synthetic routes for peptides and proteins is briefly discussed.
Lipase YS-Catalyzed Enantioselective Transesterification of Alcohols of Bicarbocyclic Compounds
Authors: Naemura Koichiro , Ida Hirotsugu , Fukuda Ritsuko 
Published: August 2006

Abstract
Lipase YS-catalyzed enantioselective acylations of (1RS, 2RS, 4RS, 5RS)-bicyclo[2.2.1]heptane-2,5-diol, (1RS, 2SR, 4RS, 5SR)-bicyclo[2.2.2]octane-2,5-diol, (1RS, 2RS, 4RS, 5RS)-bicyclo[2.2.2]octane-2,5-diol, and (1RS, 2SR, 5RS, 6SR)-bicyclo[3.3.1]nonane-2,6-diol with aryl acetates such as phenyl acetate, 1-naphthyl acetate, and 2-naphthyl acetate gave the monoacetates and the diols in optically active forms. The optical purities of (+)-(2R, 5R)-2-acetoxybicyclo[2.2.1]heptan-5-ol, (−)-(1S, 2R, 4S, 5R)-2-acetoxybicyclo[2.2.2]octan-5-ol, and (+)-(2R, 6R)-2-acetoxybicyclo[3.3.1]nonan-6-ol obtained using phenyl acetate were higher than those of the monoacetates which have been resolved by PLE-catalyzed hydrolysis of the corresponding racemic diacetates. Enzymic acylations of the diols using phenyl esters such as phenyl propanoate, phenyl butanoate, and phenyl octanoate as acylating agents gave the corresponding monoesters, which showed nearly the same enantiomeric excess value as the acetates. A simple model for predicting which enantiomer of racemic alcohols is acylated preferentially by lipase YS-catalyzed enantioselective transesterification is proposed on the basis of the results obtained here.
Reactivities of Stable Rotamers. XXXI. Bromine Addition to the Olefinic Moiety of Rotameric 1-(9-Fluorenyl)-2-(1-methylethenyl)naphthalenes
Authors: Oki Michinori , Shionoiri Katsumi , Otake Katsumasa , Ono Masaru , Toyota Shinji 
Published: August 2006

Abstract
Reaction of bromine with the ap form of the title compound afforded a normal addition compound, whereas the same with the sp form did no addition compound but a pair of bromo-olefins and a cyclized product, formation of which can be rationalized by deprotonation from and by attack of the π-system of the fluorene group on the intervening cation. The abnormal reactions of the sp form are the consequence of the steric effects of the fluorene moiety that prohibits the formation of the tetrahedral carbon at the reaction site. The stereochemistry of the cyclized product was determined both by NOE experiments and by X-ray crystallography. The stereoselective formation of only one isomer was rationalized by the structure of the starting material, of which stereodynamics was studied by the dynamic NMR method, and the direction of the attack of the bromine cation. For comparison of the fate of the intervening cation, the adduct from the ap form was treated with silver p-toluenesulfonate. It was found that the ratios of olefin formation were different from one rotamer to another. The results are discussed on the basis of different degree of openness of the intervening bromonium cation with reference to the same reaction for (1,2-dibromo-1-methylethyl)benzene.
Effects of the Linkage Length and Substituents on the Photocycloaddition of Bis(vinylnaphthyl)alkanes toward Naphthalenophanes
Authors: Nishimura Jun , Takeuchi Motoharu , Koike Masayuki , Sakamura Hideki , Yamashita Osamu , Okada Joji , Takaishi Naotake 
Published: August 2006

Abstract
Many naphtalenophanes, including a dicarbomethoxy-substituted one, a di-4-pyridyl-substituted one, and a bis(trimethylsilyl)-substituted one, were synthesized by applying intramolecular [2+2] photocycloaddition of α,ω-bis(1-vinylnaphthyl) alkanes. The effect of the linkage and substituents at the α and/or β positions of the vinyl groups was investigated concerning this photocycloaddition. From the results of the investigation, the limitation and scope of the photocycloaddition toward naphthalenophanes has been established.
In addition to this preparative study, an anomalous transannular photoproduct, which was formed from cis, exo-1,2-ethano-syn-[2.3](1,4)naphthalenophane and analyzed by X-ray crystallography, was found to undergo thermal cycloreversion through diene and tetraene intermediates. The kinetics of this reversion were studied. Moreover, some obtained naphthalenophanes showed an interesting tendency to form 1 : 1 mixed crystals with small flat-shaped recrystallization solvents having donor substituents. This nature is also briefly reported.
Application of Macroporous Glucomannan Hard Gel to High Performance Liquid Chromatographic Preparation of Coagulation Factor VIII
Authors: Yamaguchi Masato , Yamamoto Tetsuro , Tomoda Takashi , Motozato Yoshiaki 
Published: August 2006

Abstract
Glucomannan spherical hard gels with macroporous nature were 2-diethylaminoethylated (DEAE–) and evaluated for the applicability to preparation of blood coagulation factor VIII.
Adsorption capacity measured by a batch-wise method, of various kinds of DEAE-spherical gels to factor VIII in plasma cryoprecipitate fraction was apparently dependent on Mlim of the gels. DEAE-GM gel (Mlim 1 × 107) possessed the capacity at least 2 to 3 fold higher than those of EMD DEAE-650®, DEAE-Toyopearl 650® and DEAE-Cellulofine A-800®. DEAE-GM gel (Mlim 1 × 107) was applied to high performance liquid chromatographic (HPLC) preparation of factor VIII from plasma cryoprecipitate fraction under high flow rates as rapid as 1 to 4 m h−1 in linear velocity. DEAE-GM gel columns in HPLC possessed the high adsorption capacity (30 to 60 U/ml–gel) and good elution recovery from column (51—83%) accompanied by the resulting specific activity as good as 22-113 U/mg–protein. DEAE-GM gel must be a suitable tool in column chromatographic separation of factor VIII and other large proteins in manufacture scale.
Preparation of Niobia/Alumina as a Mixed Oxide Aerogel
Authors: Maurer Scott M , Ko Edmond I 
Published: August 2006

Abstract
A niobia (Nb2O5)/alumina (Al2O3) mixed oxide, containing 25 weight percent niobia, was synthesized as an aerogel by using alkoxides as precursors and supercritical carbon dioxide in the drying step. After calcination at 773 K for two hours, this sample had a BET surface area of 450 m2 g−1 and was X-ray amorphous, and contained primarily Lewis acid sites.
Effect of Trifluoperazine-Binding on Aggregates of S-100 Proteins
Authors: Matsuda Sadayuki 
Published: August 2006

Abstract
Aggregates (oligomers) of both S-100b and a mixture of S-100a and S-100a′ (S-100a.a′) were characterized using HPLC of gel filtration. The addition of trifluoperazine to S-100a.a′ resulted in the disappearance of the aggregates irrespective of zinc ion binding. The aggregates of S-100b dissociated into dimeric form of S-100b only in the presence of EDTA.
Relative Reactivities of Some Polycyclic Aromatic Hydrocarbons in Catalytic Hydrogenation over Raney Nickel
Authors: Minabe Masahiro , Urushibara Shuuichi , Mishina Fumihiko , Kimura Takao , Tsubota Motohiro 
Published: August 2006

Abstract
Catalytic hydrogenation of 9H-fluorene (1), phenanthrene (2), 4H-cyclopenta[def ]phenanthrene (3), pyrene (4), and fluoranthene (5) was carried out over Raney nickel (W-7) at 323 K under 608 kPa of hydrogen. The order of the reaction rate was 5 &gt; 4 &gt; 3 &gt; 2 &gt; 1. The adsorption equilibrium constant of the substrates decreased in the order 4 ≥ 5 &gt;&gt; 2 &gt; 3 &gt;&gt; 1.
Effect of Ether Oxygen in Isomeric Alcohols on Water Structure Estimated from Ultrasonic Absorption and Velocity Data
Authors: Nishikawa Sadakatsu , Matsumura Kenichi , Ueda Masayuki 
Published: August 2006

Abstract
4-Methoxy-1-butanol was synthesized form 1,4-butanediol through potassium 4-hydroxy-1-butoxide. The ultrasonic absorption coefficients in the frequency range from 9.5 to 220 MHz and the sound velocity at 2.5 and 1.92 MHz were measured in aqueous solutions as a function of the concentration. A single relaxational absorption was observed, the cause of which was attributed to the perturbation of an equlibrium associated with a solute–solvent interaction. The rate and thermodynamic parameters associated with the interacion were determined from the concentration dependence of the relaxation frequency. The results were compared with those for other isomeric alcohol solutions, and the effect of the alcohols on the water structure was considered in relation to the molecular structures of the solutes. It has been found that the position of the ether oxygen in the alcohol molecules gives rise to a considerable change in the solution properties.
A Revised MM2 Force Field for the Normal Mode Vibrational Analysis of Glucopyranose
Authors: Murata Masashi , Yoshie Naoko , Sakurai Minoru , Inoue Yoshio 
Published: August 2006

Abstract
A revised MM2 force field is developed for the study of normal mode dynamics of glucopyranose. The revised potential function is found to reproduce the vibrational spectrum and equilibrium structure of d-glucopyranose better than the original parameter set.
High Affinity of a Macrobicyclic Cu(II) Complex to Halide Ions and Application of the Complex in Kinetics of the Menschutkin Reaction
Authors: Kang Shin-Geol , Jung Soo-Kyung , Kim Mi-Seon , Park Jong-Hwan , Yoh Soo-Dong 
Published: August 2006

Abstract
The equilibrium constants (K) for the reaction [Cu(A)]2+ + X− [Cu(A)X]+ (A = 1,3,6,9,12-pentaazabicyclo[10.2.1] pentadecane; X− = Br− or Cl−) in acetonitrile, DMF, and DMSO have been determined at 25 °C. The large K values (&gt;8.8 × 104) and other results show that the copper(II) complex can be used as a probe for kinetic study of the Menschutkin reaction even in the basic solvents.
Convenient Synthesis of Some Styrylpyridinium Dyes Containing Methylenebis[benzenamine] Moiety
Authors: Peesapati Venkateswarlu , Rao Ummaneni Narasimha , Pethrick Richard A 
Published: August 2006

Abstract
Condensation of 4-vinylpyridine with 4,4′-[(4-bromophenyl) methylene]bis[benzenamine] and its N-ethyl analogue adopting Heck's reaction yielded corresponding new styrylpyridines which were converted into their pyridinium bromides. All the compounds reported were characterized by analytical and spectral data.
X-ray Structures and Dipole Moments of Tropones Annulated with Furan, Benzene, and Oxepin
Authors: Kudoh Mitsutaka , Sudoh Susumu , Katagiri Shigeyoshi , Nakazawa Tomoo , Ishihara Mariko , Jinguji Mamoru , Higashi Miwako , Yamaguchi Hiroyuki , Miyatake Ryuta , Sugihara Yoshikazu , Kabuto Chizuko 
Published: August 2006

Abstract
The precise X-ray structures of furo[3,4-d]tropone (2), 2,4-dimethyl-8H-3-oxaheptalen-8-one (5), and 4,5-benzotropone (6) were determined. Their tropone rings show definite bond alternation and nearly planar conformation, though slightly boat-shaped like polycyclic tropone. The ground-state dipole moments of 2, 5, and 6, and also 8H-3-oxaheptalen-8-one (3) and 2-methyl-8H-3-oxaheptalen-8-one (4) were measured in benzene at 25 °C. Analyses of the ground-state dipole moments by means of ab initio calculations demonstrate that the polar structures of 2 and 6 having an annulated aromatic ring are based on the local dipoles of penta-1,4-dien-3-one and the induced dipole of the annulated ring, whereas those of 3 and 5 are based not only on the local dipoles but also on the partial intramolecular CT interaction from the olefinic oxepin ring to the pentadienone moiety. According to the McRae equation, the dipole moments of the two lowest excited states of 2, 3, 5, and 6 were evaluated by using the frequency shifts of the absorption maxima in a number of polar and nonpolar solvents. They are all oriented in the same direction as that of the ground state, but are greater in magnitude.
Inclusion Properties of 11b-Substituted 2,3,5,6,11,11b-Hexahydro-3-oxo-1H-indolizino[8,7-b]indole-5-carboxylic Acid Esters. New Chiral Host Compounds Derived from l-Tryptophan
Authors: Morinaga Masanori , Taniguchi Masahiro , Sonogi Tsuyoshi , Watanabe Gou , Kitawaki Takaya , Kondo Mitsuru , Irikawa Hajime 
Published: August 2006

Abstract
New chiral host compounds have been prepared from l-tryptophan and 3-aroylpropionic acids. These hosts show broad inclusion and sorption abilities toward solvent and racemic molecules, and are characterized by X-ray crystallographic analysis, which clarify the one-dimensional channel structures of the hosts, the helical arrangements of the guests, and the occurrence of weak interactions such as C–H···O and C–H···Cl between the hosts and the guests. The TG and DTA data show the high cohesion of the hosts, and the PXRD patterns indicate that the crystal structures of the hosts remain ordered after removal of the guest molecules. These hosts have potential usefulness in the optical resolution of racemic guest molecules such as s-butyl chloride and 4-methylcyclohexene.
Diels–Alder Reaction of Cyclopentadienone Acetal with Pyrrole and Indole
Authors: Sato Sota , Fujino Tomoko , Isobe Hiroyuki , Nakamura Eiichi 
Published: August 2006

Abstract
Diels–Alder reactions of a cyclopentadienone acetal with aromatic heterocycles, such as pyrrole or indole, took place with the latter acting as a 2π dienophile. The reaction gave a polycyclic heterocycle in good yield regioselectively. Analysis of the frontier molecular orbitals showed that inverse electron demand interactions control the regioselectivity.
A simple linear sweep voltammetric method for the determination of double-stranded DNA with malachite green
Authors: Sun W. , You J. , Hu X. , Jiao K. 
Published: August 2006

AbstractIn pH 3.5 Britton—Robinson buffer solution double-stranded (ds) DNA can react with malachite green (MG) to form an interaction complex, which resulted in the decrease of the electrochemical response of MG, MG had a well-defined second-order derivative linear sweep voltammetric peak at −0.73 V (vs. SCE). After the addition of dsDNA into MG solution, the reductive peak current decreased with the positive shift of peak potential, which was the typical characteristic of intercalation. Based on the interaction, an indirect electrochemical determination method for dsDNA was established. The optimum conditions for the reaction were investigated and there were little or no interferences from the commonly coexisting substances. The decrease of peak current was linear with the concentration of dsDNA over the range of 0.8–12.0 µg cm−3 with the linear regression equation as ΔI p″/nA = 91.70 C/(µg cm−3) + 74.55 (n = 10, γ = 0.990). The detection limit was calculated as 0.46 µg cm−3 (3σ). The method had high sensitivity and was further applied to the dsDNA synthetic samples with satisfactory result. The interaction mechanism was discussed with the intercalation of DNA-MG to form a supramolecular complex and the stoichiometry of the supramolecular complex was calculated by electrochemical method with the binding number 3 and the binding constant 2.35 × 1015 (mol dm−3)−3.