bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Aggregation of a Merocyanine Dye in Solution and Film
Authors: Mizutani Fumio , Iijima Sei-ichiro , Tsuda Keishiro 
Published: July 2006

Abstract
Two low-energy bands, one near 595 nm and the other near 630 nm, were observed in the visible absorption spectra of a merocyanine dye (3-carboxymethyl-5-[2-(3-octadecyl-2-benzothiazolinylidene)ethylidene]-2-thioxo-4-thiazolidinone) dissolved in methanol–water mixtures containing KOH and Triton X-100. From the dye-concentration dependence on the spectra, the band near 595 nm was assigned to the tetramer, and the one near 630 nm, (probably) to the hexamer of the carboxylate form of the dye. The same bands were observed in the dye films when they were soaked in aqueous solutions of pH≥5.5. The relative intensities of the two bands were strongly affected by the ionic strength of the aqueous solution.
The Reduction of Cobalt(III) Complexes by Ascorbic Acid. II. The Kinetics and Mechanisms of the Reactions of Diaqua and Aquahydroxo Macrocyclic N4 Complexes
Authors: Tsukahara Keiichi , Izumitani Tatsuo , Yamamoto Yasuo 
Published: July 2006

Abstract
The kinetics of the reductions of several macrocyclic N4 cobalt(III) complexes by l-ascorbic acid (H2A, have been studied at 25.0 °C, at an ionic strength of 0.10 mol dm−3 (LiClO4), and over the pH range from 1.64 to 3.47. The second-order rate constants in dm3 mol−1 s−1 are 3.4±0.6 (Me6[14]4,11-dieneN4), (4.2±0.2)×10 (Me4[14]tetraeneN4), and (4.2±0.1)×10 (ms-Me6[14]aneN4) for the reactions of [Co(N4)(H2O)2]3+ with HA− ions and (1.1±0.1)×102 (Me6[14]4,11-dieneN4), (1.3±0.1)×103 (Me4[14]tetraeneN4), (5.5±0.1)×10 (ms-Me6[14]aneN4), and (2.9±0.6)×10 ([14]aneN4) for the reactions of [Co(OH)(N4)(H2O)]2+ with HA− ions. The mechanisms of these reactions are discussed, and it is concluded that the lack of saturation of macrocyclic ligands facilitates the electron-transfer reaction between cobalt(III) and ascorbic acid.
Mechanism of Copper Transport through a Diaphragm-type Liquid Membrane
Authors: Kataoka Takeshi , Nishiki Tadaaki , Ueyama Koretsune 
Published: July 2006

Abstract
The permeation mechanism of copper with a liquid membrane process was studied by measuring the permeation rate of copper, which was allowed to permeate through a diaphragm-type liquid membrane with LIX64N as a mobile carrier at various concentrations of carrier and acid. The permeation rate is explained approximately by the diffusional process in the membrane for a chelating complex between copper and carrier and by the succeeding stripping reaction at the interface between the membrane and stripping phase.
Photodimerization of Indeno[2,1-a]indene
Authors: Shim Sang Chul , Chae Jeong Seok 
Published: July 2006

Abstract
Indeno[2,1-a]indene, a trans-stilbene analogue with fixed planar configuration, yielded a head-to-head and a head-to-tail C4-cyclodimer on direct irradiation with 300 nm UV light. The fluorescence quenching and sensitization studies indicated the reaction to proceed through excited singlet state, very likely through the singlet excimer intermediate.
Spectral Changes in X-Ray K Emission Lines of Potassium in Various Compounds
Authors: Yasuda Seiji , Kakiyama Hitoo 
Published: July 2006

Abstract
The chemical shifts and profile changes in the Kα1,2, Kβ1,3 and their satellite lines of potassium from 21 chemical compounds were measured with a two-crystal X-ray spectrometer. The data obtained are discussed qualitatively and related to the nature of the surrounding groups.
A New Efficient and Stereoselective Synthesis of Ubiquinone-10
Authors: Fujita Yoshiji , Ishiguro Michihiro , Onishi Takashi , Nishida Takashi 
Published: July 2006

Abstract
Coupling reaction of 6-cupro-2,3-dimethoxy-5-methylhydroquinone bis(2-methoxyethoxymethyl) ether with (2E)-1-(phenylsulfonyl)-2-methyl-4-chloro-2-butene afforded the sulfone-functionalized prenylhydro quinone (6) in 82% yield. Stereoselective synthesis of ubiquinone-10 was achieved by the condensation of 6 and solanesyl bromide (yield 92%), reductive elimination of the sulfone group by sodium–ethyl alcohol in THF (yield 80%), and followed by air oxidation of the hydroquinone.
Reduction of α,β-Unsaturated Carbonyl Compounds to the Saturated Alcohols Using Hydridocarbonyliron Complexes
Authors: Yamashita Masakazu , Miyoshi Kanako , Okada Yasuhiro , Suemitsu Rikisaku 
Published: July 2006

Abstract
Tetracarbonylhydridoferrate was found to be effective for the selective reduction of α,β-unsaturated carbonyl compounds to the corresponding saturated alcohols. The reactions proceeded stereospecifically and (−)- and (+)-neodihydrocarveol were obtained exclusively from (+)- and (−)-carvone respectively. The reaction mechanism is briefly discussed.
Pressure Effect on Reaction Rate of Cycloaddition of Tetracyanoethylene with α-Methylstyrene in Some Aprotic Solvents
Authors: Tsuzuki Hideaki , Uosaki Yasuhiro , Nakahara Masaru , Sasaki Muneo , Osugi Jiro 
Published: July 2006

Abstract
The high-pressure kinetic study of the title reaction was carried out at 25 °C up to 1500 bar in carbon tetrachloride, chloroform, 1,2-dichloroethane, and acetonitrile, taking into account the role of the EDA complex formation. The dipole moment at the transition state is as large as 8.5±0.5 debye by Kirkwood’s electrostatic model. The solvent effect is also ascribable to the polarity change upon activation. The intrinsic volume of activation is −27±3 cm3/mol for the cycloadding process and −3.3±3 cm3/mol for the reverse reaction.
The Structure of the Cyclodextrin Complex. XII. Crystal Structure of α-Cyclodextrin-1-Phenylethanol (1:1) Tetrahydrate
Authors: Harata Kazuaki 
Published: July 2006

Abstract
The crystal structure of the α-cyclodextrin-1-phenylethanol (1:1) tetrahydrate, C36H60O30·C8H10O·4H2O, was determined by the X-ray method. The crystal is monoclinic, the space group being P21 with Z=2; the cell dimensions are a=8.176(1), b=23.930(2), c=13.853(1) Å, and β=106.69(1)°. The structure was solved by means of the Patterson map and the trial-and-error method combined with the rigid-body least-squares technique. Refinement was carried out by the block-diagonal least-squares method to the final R-value of 0.040 for 3565 reflections. α-Cyclodextrin molecules are stacked along the a axis in the head-to-tail fashion to form a channel-type structure, and are tilted by 17.0° against the channel axis. Owing to the lateral shift of α-cyclodextrin ring parallel to the molecular plane, neighboring α-cyclodextrin molecules along the channel are linked by only one weak hydrogen bond. The 1-phenylethanol molecule is sandwiched between stacked α-cyclodextrin molecules. S-(−) and R-(+) isomers of 1-phenylethanol are each located at the same position with the statistical disorder of the hydroxyl group with the occupancy of 0.5. Columns formed by the stack of α-cyclodextrin are closely packed, being linked with one another by many hydrogen bonds. Water molecules are located in two kinds of intermolecular spaces between α-cyclodextrin columns.
A Polarographic Study of Bis(benzoylacetonato)nickel(II) in Dimethyl Sulfoxide
Authors: Kudo Setsuko , Iwase Akio , Mogi Iwao , Tanaka Nobuyuki 
Published: July 2006

Abstract
The chemical equilibria of bis(benzoylacetonato)nickel(II) in dimethyl sulfoxide solutions were investigated, mainly by means of d.c. polarography. In 0.05–0.1 mol dm−3 NaClO4, TMAP, and TBAP solutions, the following chemical equilibria were found: Ni(bi-bzac)2\ightleftharpoonsNi(bi-bzac)(uni-bzac)\ightleftharpoonsNi(bi-bzac)+\ightleftharpoonsNi(uni-bzac)+ where bi- and uni- are the abbreviations of bidentate and unidentate respectively. The species of Ni(bi-bzac)2 and Ni(bi-bzac)(uni-bzac) comprised 35% and 57% respectively of the total complex of 1 mmol dm−3 in a TMAP or TBAP solution, while they accounted for 15% and 77% respectively in a NaClO4 solution. Such a difference in the equilibrium distribution was explained on the basis of the interaction between π electrons of the ligand and cations of the supporting electrolytes. The tris-complex was formed by the addition of excess benzoylacetonate to the complex solution.
Reactions of Thiols with Phenylglyoxal to Give Thiomandelic S-Esters. Formation of Hemithioacetals and Their Rearrangement
Authors: Okuyama Tadashi , Kimura Kazumasa , Fueno Takayuki 
Published: July 2006

Abstract
Equilibrium constants Kh for the addition of 2-mercaptoethanol and glutathione to phenylglyoxal to form hemithioacetals were determined spectrophotometrically over the pH range 7–10. The observed Kh values decrease sigmoidally with pH as the thiol ionizes. Rearrangement of hemithioacetals formed from phenylglyoxal and various thiols was kinetically investigated. The rates increase with thiol concentration following a saturation curve to give Kh identical with the spectrophotometric value. The rearrangement is subject to general base catalysis. The solvent isotope effect on the rate of the rearrangement, kH2O/kD2O, is nearly 1.0; that on the equilibrium, KhH2O/KhD2O, is 0.38. The results strongly support the mechanism involving proton transfers through an enediol intermediate.
Unusual Reaction of Azoxybenzenes with p-Toluenesulfonic Acid in Acetic Anhydride
Authors: Shimao Ichiro , Fujimori Ken , Oae Shigeru 
Published: July 2006

Abstract
Treatment of azoxybenzene with p-toluenesulfonic acid in acetic anhydride gave tosylates of 4- and 2-(phenylazo)phenols, and the corresponding acetates as by-product, besides azobenzene. However, a similar reaction of 4,4′-difluoroazoxybenzene gave 2-tosyloxy-4,4′-difluoroazobenzene as rearrangement product, besides 4-fluorophenyl tosylate and 4-fluorophenyl acetate. Meanwhile, the reaction of 4,4′-diacetoxyazoxybenzene afforded 4-acetoxyphenyl tosylate and hydroquinone diacetate in high yields. These unique reactions involve C–N bond cleavage, and may proceed through a pathway involving formation of benzenediazonium ion as the key intermediate.
A Stereoselective One-stage α-Glucosylation with 2,3,4,6-Tetra-O-benzyl-α-d-glucopyranose and a Mixture of Methanesulfonic Acid, Cobalt(II) Bromide, and Tetraethylammonium Perchlorate
Authors: Koto Shinkiti , Morishima Naohiko , Zen Shonosuke 
Published: July 2006

Abstract
A one-stage procedure for the stereoselective α-glucosylation of alcohol with 2,3,4,6-tetra-O-benzyl-α-d-glucopyranose and a mixture of methanesulfonic acid, cobalt(II) bromide, and tetraethylammonium perchlorate is described. The mechanism of the glucosylation reaction is discussed.
Solid-phase Synthesis of Substrate Model Peptides and Their Hydroxylation with Collagen Lysyl Hydroxylase
Authors: Kikuchi Yasuo , Tamiya Nobuo 
Published: July 2006

Abstract
The peptides, (Ala–Lys–Gly)10–Phe, (Ile–Lys–Gly)3–Phe, and (Ile–Lys–Gly)5–Phe, were synthesized by solid-phase fragment condensation method. The contaminating shorter peptides and branched chain peptides were removed by CM-cellulose column chromatography. The peptides were useful as synthetic model substrates for collagen lysyl hydroxylase. The –Ile–Lys–Gly– units in (Ile–Lys–Gly)5–Phe showed a higher affinity to the enzyme than those in (Ile–Lys–Gly)3–Phe. A strong substrate inhibition was observed with highly basic peptide, (Ala–Lys–Gly)10–Phe.
Six New Sesquiterpenoids from the Red Alga Laurencia nipponica Yamada
Authors: Suzuki Teruaki , Kikuchi Hajime , Kurosawa Etsuro 
Published: July 2006

Abstract
Six new laurane-type sesquiterpenoids were isolated from the red alga Laurencia nipponica Yamada and their structures were established on the basis of spectral and chemical evidence.
Infrared Spectra and Intramolecular Hydrogen Bonding of Some Salicylanilides of Pharmaceutical Interest
Authors: Endo Hiroko , Hirota Minoru , Ito Yoshio , Takeuchi Isao , Hamada Yoshiki 
Published: July 2006

Abstract
Intramolecular hydrogen bonding of the title compounds was investigated by measuring their infrared spectra in the OH, NH, and C=O stretching regions. The results showed that the intramolecular hydrogen bonding in the salicyloyl moiety plays an important role in the antibacterial activities of these salicylanilides.
Pyrene-cation Formation on Reactions of Pyrene Triplet State with Metal Ions in Caffeine-solubilized Aqueous Solution
Authors: Nosaka Yoshio , Kira Akira , Imamura Masashi 
Published: July 2006

Abstract
Quenching of triplet states of pyrene and other aromatic hydrocarbons by metal ions in caffeine-solubilized aqueous solution was investigated. The concomitant formation of aromatic cations was observed on quenching of triplet pyrene by Hg2+ and Fe3+ and triplet phenanthrene and benz[a]anthracene by Hg2+.
Apparent Molar Volumes of Water in Methanol and Tetrahydrofuran at 298.15 K
Authors: Sakurai Masao , Nakagawa Tsurutaro 
Published: July 2006

Abstract
The densities of water–methanol(MeOH) and water–tetrahydrofuran(THF) mixtures have been measured at 298.15 K. The apparent molar volumes of water, Vφ,w, have been derived as a function of concentration. The values of Vφ,w in MeOH increase monotonously with the concentration, while for THF solutions the Vφ,w curve passes through a minimum at low mole fraction of water. These are interpreted in terms of the formation of water–organic solvent and water–water hydrogen bonding.
Photo- and Thermally-induced Radical Rearrangements of 6-Methyl- and 4,4,6-Trimethylcholest-5-en-3β-ol
Authors: Suginome Hiroshi , Maeda Norio , Seki Yoshikatsu , Orito Kazuhiko 
Published: July 2006

Abstract
The irradiation of 6-methylcholest-5-en-3β-ol in benzene containing mercury(II) oxide and iodine gave 3α,5-epoxy-6-methylene-A-homo-4-oxa-5α-cholestane (23%) and 2-iodo-6-methyl-A-nor-2,3-secocholest-5-en-3-yl formate (32%). The thermally-induced reaction at 55–60 °C gave the former in a 16% yield. The corresponding photo-reaction of 4,4,6-trimethylcholest-5-en-3β-ol, however, gave 4,6-dimethyl-4-methylene-3,4-secocholest-5-en-3-al.
The Racemization of Glutamic Acid Induced by Aliphatic Aldehydes
Authors: Yamamoto Mihoko , Ozaki Hiroshi , Tai Akira , Izumi Yoshiharu 
Published: July 2006

Abstract
The real catalytic species in the racemization of glutamic acid induced by acetaldehyde was investigated and found to be 2-butenal produced in situ from acetaldehyde.
An MO Study of the Photochemical Electrocyclic Isomerization between Vinylketene and Cyclobutenone
Authors: Kikuchi Osamu 
Published: July 2006

Abstract
The MINDO/3 CI potential energy surfaces of the vinylketene–cyclobutenone system suggest that the cyclization of vinylketene occurs from the π→π* state via the zwitterion, in which the negative charge is located on the 90°-twisted methylene carbon atom, while the reverse reaction proceeds via a diradical structure.
Stereochemistry of Friedel-Crafts Reaction of Benzene with Optically Active 2-Methyloxetane
Authors: Segi Masahito , Takebe Masaki , Masuda Shinji , Nakajima Tadashi , Suga Sohei 
Published: July 2006

Abstract
The Friedel-Crafts alkylation of benzene with (+)-2-methyloxetane in the presence of Lewis acids (AlCl3, SnCl4, and TiCl4) gave 3-phenyl-1-butanol with 20–60% inversion of configuration at the reaction center and a mixture of 4-chloro-2-butanol and 3-chloro-1-butanol in optically active form as the by-products. These by products were formed by the attack of the chlorine atom in Lewis acid. The stereochemical course of the reaction to 3-chloro-1-butanol varied with the kind of catalyst, i.e., inversion with AlCl3 or TiCl4 and retention with SnCl4. The addition of nitromethane to the reaction system promoted the retentive ring-opening to 3-chloro-1-butanol.
ESR Studies of Cobalt(II) in [TMPD+]2[Ni(mnt)2] and [TMPD+]2[Pt(mnt)2](TMPD+: N,N,N′,N′-Tetramethyl-p-phenylenediamine Cation, mnt: 1,2-Dicyano-1,2-ethylenedithiolato)
Authors: Setoi Tomoyoshi , Inoue Motomich , Nakamura Daiyu 
Published: July 2006

Abstract
The Co(II) and triplet exciton ESR spectra of Co(II)-doped [TMPD+]2[Ni(mnt)2] and [TMPD+]2[Pt(mnt)2] were observed at different temperatures. The triplet exciton signals of the solid solutions yielded practically the same ESR parameters as those of the pure Ni(II) and Pt(II) complexes. The Co(II) spectra showed a wellresolved hyperfine structure, each component line of which became broad with increasing temperature. This can be interpreted in terms of exciton transfer from TMPD+ lattices to the metal ions.
The Insertion Reaction of NH Singlet Radicals into the C–H Bonds of Cyclopropane and Isobutane in the Liquid Phase
Authors: Hamada Jun-ich , Tsunashima Shigeru , Sato Shin 
Published: July 2006

Abstract
Hydrogen azide was photolyzed in liquid cyclopropane at the temperature of Dry Ice–methanol. The main products observed were nitrogen, cyclopropylamine, and ammonia. The relative yields of the products depended slightly on the concentration of hydrogen azide. The results were then compared with those obtained with paraffin and olefin. The isobutane solution of hydrogen azide was photolyzed at 0 °C. The products observed were the same as those obtained at the temperature of Dry Ice-methanol. The relative yields of the products and the concentration dependence, however, were different.
Solvent Effects on the Fluorescence Quantum Yields and Lifetimes of 1- and 2-Acetyl- or Benzoylanthracenes
Authors: Tamaki Takashi 
Published: July 2006

Abstract
The fluorescence quantum yields and lifetimes of 1- and 2-acetyl- or benzoylanthracenes were measured in various degassed solvents at room temperature. The natural fluorescence lifetime was evaluated to be 30–40 ns, depending a little on the compounds, but little on the solvent. This strongly supports the recent finding that the lowest excited singlet state of the acylanthracenes is of a ππ* character. On the basis of triplet-yield measurements, it was also confirmed that the low fluorescence yield in nonpolar solvents is due to an efficient intersystem crossing to an upper triplet state.
The Photoassociation of 1- and 2-Acetylanthracenes with Methanol
Authors: Tamaki Takashi 
Published: July 2006

Abstract
The effect of small amounts of methanol (≤0.34 mol dm−3) upon the absorption and fluorescence spectra of 1- and 2-acetylanthracenes in hexane was investigated. While the formation of a 1 : 1 hydrogen-bonded complex in the ground state was revealed by the isosbestic points of the absorption spectra, the change in the fluorescence spectra was indicative of the photogeneration of a highly associated complex which includes at least two alcohol molecules. On the assumption that the excited 1 : 1 complex further associates with an alcohol molecule, the computer simulation by the least-squares method provided a good fit of the observed concentration dependence of methanol upon the fluorescence quantum yield. The photokinetic parameters and the thermodynamic quantities were evaluated from the parameter values.
Correlation between Critical Solution Phenomena and Ultralow Interfacial Tensions in a Surfactant/Water/Oil System
Authors: Kunieda Hironobu , Shinoda K\={o}z\={o} 
Published: July 2006

Abstract
A three-phase region consisting of surfactant (D), water (W), and oil (O) phases appeared due to the superposition of two critical phenomena of D–W and O–D in a nonionic surfactant/water/oil system. Three interfacial tensions, γO–W, γO–D and γD–W, among the three phases were determined at various temperatures. The generalized Antonoff’s rule (γO–W=γO–D+γD–W) holds approximately in the three-phase region. γO–D and γD–W disappear at the respective critical solution temperatures, and ultralow interfacial tensions are attained in the vicinity of both critical temperatures. The oil–water interfacial tension, γO–W, reaches its minimum in the midst of the temperature range of the three-phase region, and the narrower the temperature range of the three-phase region, the lower the interfacial tension. The correlation between the interfacial tensions and the types of emulsions is also discussed.
A Proton Magnetic Resonance Study of Dialkyl Terephthalate Dianions
Authors: Hirayama Masatoshi , Kaneko Mitsuo 
Published: July 2006

Abstract
NMR spectra were observed for green solutions formed from dimethyl, diethyl, and diisopropyl terephthalates in contact with sodium metal in THF-d8 in vacua at ambient probe temperature. A comparison of proton chemical shifts with excess charge densities calculated by the CNDO MO method supports that the green species are disodium salts of π-dianions.
Anion Exchange Separation of Hard Acid-metals Using HF–H3BO3 Media
Authors: Adachi Takeo 
Published: July 2006

Abstract
The properties of HF–H3BO3 media and the distribution coefficients of eighteen metals have been investigated to achieve the separation of hard acid-metals by the anion exchange method. As the addition of boric acid to hydrofluoric acid solution reduces the free fluoride ion concentration to about one hundredth, it is possible to control the formation of metal fluoride complexes in a way favorable for the separation. The BF4− and BF3OH− produced in this media are adsorbed strongly to the resin and reduce the relative adsorbabilities of metal fluoride complexes remarkably. Using these properties of HF–H3BO3 media and the adsorbabilities of other anions, a new anion exchange method for the separation of hard acid-metals has been proposed. The new method is especially useful for the separation of titanium, zirconium, niobium, and tantalum. Distribution coefficients and elution behaviors of metal ions are not affected by the increase of the amount of metals because of the buffer action relating to the fluoride in HF–H3BO3 media.
Influences of the Lanthanoid Contraction on the Thermal Dehydration Reactions of Lanthanoid(III) Malonate Hydrates
Authors: Muraishi Kazuo , Nagase Kenzo , Kikuchi Masae , Sone Kozo , Tanaka Nobuyuki 
Published: July 2006

Abstract
The thermal dehydration reactions of lanthanoid(III) malonate hydrates Ln2mal3·nH2O (Ln=Ce–Lu; mal=CH2(COO)2; n=6 for Ce–Eu and 8 for Gd–Lu) were investigated mainly by the thermogravimetries under conventional conditions and in atmosphere of water vapor at a constant reduced pressure and a superslow heating rate. The latter conditions were useful especially to detect the formation of new intermediate hydrates, and to determine the dehydration temperatures with accuracy. The main features of the results could be reasonably understood in view of the effects of the lanthanoid contraction.
The Preparation of Protoheme Mono-N-[5-(2-methyl-1-imidazolyl)pentyl]amide and Its Oxygenation
Authors: Tsuchida Eishun , Nishide Hiroyuki , Sato Yoshinori , Kaneda Manabu 
Published: July 2006

Abstract
Iron(II)protoporphyrin IX N-[5-(2-methyl-1-imidazolyl)pentyl]amide ethyl ester (1) and its derivatives (2–4) were prepared. They predominantly form pentacoordinate heme complexes in organic and aqueous solutions, based on their 2-methylimidazole-ligand and spacer N-pentylamide groups. Oxygen adducts of 1–4 were rapidly formed on exposure to oxygen in N,N-dimethylformamide (DMF) at −30 °C, and their life-times were more than 30 min.
The Effect of Polyhydric Alcohols on the Thermal Denaturation of Lysozyme as Measured by Differential Scanning Calorimetry
Authors: Fujita Yukihisa , Iwasa Yasuchika , Noda Yukinao 
Published: July 2006

Abstract
The thermal denaturation of lysozyme in aqueous solutions of polyhydric alcohols at pH 2 was investigated by differential scanning calorimetry (DSC). The polyhydric alcohols employed were inositol, sorbitol, xylitol, erythritol, glycerol, and ethylene glycol. These alcohols tended to enhance the thermal stability of lysozyme; both the temperature and the enthalpy of denaturation increased almost linearly with increasing alcohol concentration. The increase in denaturation temperature at a given alcohol concentration was a linearly increasing function of the number of hydroxyl groups per alcohol molecule. The denaturation enthalpy at identical temperature increased only slightly by the addition of polyhydric alcohol. The hypothesis may be supported that the dominant mechanism by which polyhydric alcohols stabilize proteins to thermal denaturation is through their effect on the water structure, which determines the strength of the hydrophobic interactions between the nonpolar groups of the protein.