State Ethanol Research Articles

Tribological Behavior of Ti3SiC2 against Si3N4 and Al2O3 in Flowing and Nonflowing Ethanol

This study is a continuation of our previous work. It aims to characterize the tribomechanical and tribochemical behaviors of Ti3SiC2 in low-viscosity liquids. We found an interesting phenomenon in which the flowing and nonflowing states of ethanol are related to the tribological behavior of Ti3SiC2. Low friction and wear were obtained in flowing ethanol, which is due to the lubrication of the products of tribochemical reactions, especially the oxide scales on worn surfaces. Friction and wear are worse in nonflowing ethanol than in flowing ethanol, with a complicated evolution of coefficient of friction and high wear rate. Three stages of a tribo-oxidation evolution process contribute to the complicated evolution of the coefficient of friction. First, the formation of oxide scales contributes to low friction. Second, the breakup of oxide scales results in an abrupt increase in the coefficient of friction. Finally, scratches and abrasive wear from cumulated debris in nonflowing ethanol lead to a continuous increase in friction and wear.

Synthesis and spectroscopic characterization of a photo-stable tetrazinc(II)–Schiff base cluster: A rare case of ligand centric phenoxazinone synthase activity

Herein, the synthesis, structural characterization and catalytic activity of a novel tetranuclear zinc(II)–Schiff base complex, [Zn4(L)2(µ3-OCH3)2(CH3OH)2]·2CH3OH (1), [L = N,N′-bis(3-methoxysalicylidene)-1,3-diamino-2-propanol] was presented. Single crystal X-ray diffraction structural analysis revealed that the tetra-zinc(II) cluster crystallized in a monoclinic system with P21/c space group. Interestingly, three different molecular bridges (methoxido-, alkoxido- and phenoxido-) simultaneously co-existed in assembling tetra-zinc(II) core, which was a very rare observation. To the best of our knowledge, this compound would be the first compound where a diverse coordination aspect was covered by a single solvent as terminal coordinator (CH3OH), bridging (µ3-CH3OH) and solvent for crystallization in the existing scientific literature. The compound showed good photo-stability and excellent luminescence property with higher lifetime at transition state in ethanol. This zinc(II) complex revealed crucial role as an effective catalytic system towards oxidation of 2-aminophenol (2-AP) in ethanol. Additionally, the tetra-zinc(II) complex displayed potential phenoxazinone synthase like activity with momentous turn over number, kcat (h−1) = 6.19 × 102 in ethanol under aerobic condition. ESI-MS and EPR spectral analysis of the reaction mixture between Zn(II) complex and 2-AP recommended that the course of catalysis proceeded through substrate–catalyst adduct formation and authenticated the radical mechanistic pathway in favor of oxidative coupling product. This tetranuclear zinc(II)–Schiff base complex would be considered as the first example that catalyzed the oxidative coupling of 2-aminophenol to aminophenoxazino compound under usual aerobic condition. As complementary, detailed quantum chemical computations, performed with density functional theory (DFT) were well corroborated with the experimental results. This was the first and rarest example where a tetrazinc(II)–Schiff base cluster exhibited catalytic oxidation of 2-AP through ligand centered radical activity.

Market, welfare and land-use implications of lignocellulosic bioethanol in Hawai'i

This article examines land-use, market and welfare implications of lignocellulosic bioethanol production in Hawai'i to satisfy 10% and 20% of the State's gasoline demand in line with the State's ethanol blending mandate and Alternative Fuels Standard (AFS). A static computable general equilibrium (CGE) model is used to evaluate four alternative support mechanisms for bioethanol. Namely: i) a federal blending tax credit, ii) a long-term purchase contract, iii) a state production subsidy financed by a lump-sum tax and iv) a state production subsidy financed by an ad valorem gasoline tax. We find that because Hawaii-produced bioethanol is relatively costly, all scenarios are welfare reducing for Hawaii residents: estimated between −0.14% and −0.32%. Unsurprisingly, Hawaii's economy and its residents fair best under the federal blending tax credit scenario, with a positive impact to gross state product of $49 million. Otherwise, impacts to gross state product are negative (up to −$63 million). We additionally find that Hawaii-based bioethanol is not likely to offer substantial greenhouse gas emissions savings in comparison to imported biofuel, and as such the policy cost per tonne of emissions displaced ranges between $130 and $2100/tonne of CO2e. The policies serve to increase the value of agricultural lands, where we estimate that the value of pasture land could as well.

Solvation dynamics in the plastic crystal and supercooled liquid state ofethanol

The dynamics of ethanol in its plastic crystalline and supercooled liquid state hasbeen measured using triplet state solvation dynamics techniques. This studyfocuses on temperatures near the respective glass transitions Tgof the two distinct phases, where the structural relaxation times are between 1ms and 10 s. In the plastic crystal, the correlation times of the Stokesshift dynamics match the longitudinal time constants of the system asderived from dielectric relaxation data. Additionally, a maximum of thetime resolved optical linewidths is indicative of heterogeneous dynamicsin the plastic crystal. The supercooled liquid state is obtained afterquenching the liquid from room temperature to below Tgand displays relaxation times that are a factor of 100 faster compared withthe plastic crystal at the same temperature. The results do not revealdifferent translational contributions to solvation for the two phases.

Low-temperature thermal properties of molecular glasses and crystals

We have developed two instrumental arrangements for the measurement of low-temperature specific heat and thermal conductivity of molecular glasses and crystals, which are liquid at ambient temperature. We present measurements carried out with ethanol (CH3CH2OH). Ethanol is an organic low-molecular-weight substance, which exhibits polymorphism. There are three different phases at low temperature: a stable monoclinic crystal, a conventional structural glass, and an orientational glass produced by supercooling a plastic crystalline state. Fully-deuterated ethanol (CD3CD2OD) has also been studied. The specific heat C p(T) and the thermal conductivity κ(T) of several crystalline and glassy states of ethanol have been measured in the temperature range from around 2 K up to 30 K. All structural and orientational glassy states show the so-called “anomalous” thermal properties of common inorganic glasses.

Drastic changes of photoluminescence and X-ray diffraction associating with volume instability of poly(3-alkylthiophene) gel

Photoluminescence of poly(3-alkylthiophene) gel in the expanded state in chloroform is much enhanced compared with that in the shrunken state in ethanol. Enhancement of photoluminescence is more remarkable in the gel with larger volume change. That is, the change of the luminescence intensity associating with volume instability is interpreted to be due to the change of the inter-chain distance but not simply the environmental solvent effect. From the in-situ X-ray diffraction measurement of poly(3-alkylthiophene) the inter-chain distance of the gel is confirmed to increase accompanying with volume increase. These results suggest that the volume change of poly(3-alkylthiophene) gel and their luminescence change associating with the volume instability are originated in the changes of inter-chain interaction and the probability of the radiative recombination of photo-excited species depending on the inter-chain distance.

Gel chromism and anomalous luminescence in poly(3-alkylthiophene)

The absorption spectrum of poly(3-alkylthiophene) gel changes drastically in association with a volume instability upon changing the solvent composition and also the temperature. In the expanded state in chloroform and at high temperature, the photoluminescence is much enhanced compared with the shrunken state in ethanol and at low temperature. This gel chromism and anomalous luminescence are discussed in terms of the change of effective conjugation length induced by the steric hindrance and the dynamics of the photoexcited species.

Spectroscopic and photophysical properties of some biological antioxidants: structural and solvent effects

The absorption and fluorescence spectral and photophysical properties (fluorescence quantum yields nd lifetimes) of a number of biological antioxidants were examined in three typical solvents at 298 K:3-methylpentane, acetonitrile and ethanol. Resonance charge transfer induced by the OH group in the antioxidants is the main factor contributing to the observed red shifts of the absorption spectra as compared with those of the non-hydroxylated parent compounds. The dihedral angle θ between the aromatic ring and the 2p-type lone pair of the 1-oxygen atom plays a minor role in the stabilization of the ground electronic states. Steric factors around the OH group are the main contributors. The antioxidants studied can be divided into two classes of hydrogen bonding ground state complexes: those whose OH group acts as a proton donor (γ-tocopherol (γ-toc), δ-tocopherol (δ-toc), 2[3]- t-butyl-4-hydroxyanisole (BHA) and 2,4,6-trimethylphenol (TMP) and those whose OH group acts as a proton acceptor 6-hydroxy-2,2,5,7,8-pentamethylchromane (PMHC), α-tocopherol or vitamin E (α-toc), 6-hydroxy-2,5,7,8-tetramethyl-2,3-dihydrobenzofurane (DHBF), 6-hydroxy-1-ethyl-5,7,8-trimethyl-1,2,3,4-tetrahydroquinoline (THQ) and 2,3,5,6-tetramethyl-4-methoxyphenol (TMMP). The stereoelectronic factors around the OH group are entirely responsible for the type of hydrogen bonding encountered by a particular antioxidant molecule in its ground electronic state. There is a difference between the ground and first excited singlet state geometries in all the antioxidants. The extent of charge delocalization between the ground and first excited singlet states of these molecules is at a maximum for THQ and at a minimum for TMP, emphasizing the importance of the dihedral angle θ between the 1-oxygen atom and the aromatic ring in the stabilization of the S 1 electronic states in the antioxidants. Only one type of hydrogen bonding, where the OH group acts as a proton donor, stabilizes the excited singlet state in ethanol for all the antioxidants. A concomitant decrease in the non-radiative decay rate constants in ethanol is observed and is discussed.

Divergence from statistical independence in specified clusters of adjacent neuronal spike train intervals before and after ethanol state changes.

In order to test the influence of drug-induced state changes on serial ordering of interaction potential intervals, we evaluated divergence from statistical independence of specific "clusters" of various numbers of adjacent intervals. Such divergence, which was highly significant statistically, was noted using two different methods, one based on relative interval duration, and the other based on categorizing intervals as to short, medium, or long. Before ethanol, significant divergence was seen for clusters of as many as 5-6 adjacent intervals, and this same degree of serial ordering was seen after ethanol. While the apparent cluster length remained unchanged by ethanol, the specific clusters which contributed most to the statistical significance, were generally not the same after ethanol. This suggests that neurons process intervals as "clusters" of a given length but that specific "clusters" may be important "information carriers" in the nervous system. The methodology outlined herein may allow us to identify these important "clusters."

Molecular motions in polymorphic forms of ethanol as studied by nuclear magnetic resonance

Measurements were made of the temperature dependence of the N.M.R. lineshape between 32 and 159 K and the spin-lattice relaxation time T 1 between 56 and 190 K at 10 MHz to study the molecular motion in various states of ethanol and ethanol-D. The methyl group reorientation about C 3 axis is the main relaxation mechanism in the stable crystalline phase, having an activation energy of 12·6 kJ mol-1 and τc 0 = 3·3 × 10-13 s. The molecular tumbling together with rapid methyl rotation is responsible for the dominant relaxation mechanism in the undercooled liquid and the metastable plastic phase. On the other hand, T 1 in the glassy liquid and the glassy crystal may be described by a quantum picture, i.e. the tunnelling rotation of the methyl group. The slope of the T 1 curve for these glassy states corresponds to the separation between the ground and the first excited torsional levels, which is 1·9 kJ mol-1. The tunnelling splitting was deduced to be 15 ± 5 MHz and the barrier height 8 ± 1 kJ mol-1.

The effect of external stimulus change on ethanol-produced dissociation

Rats which were subjected to aversive Pavlovian conditioning while in a state of ethanol-produced intoxication showed significantly less conditioned suppression of water drinking in the non-drugged state only if the external stimulus situation was also changed between conditioning and testing. This interaction between internal and external stimulus change supports a generalization-decrement explanation of drug-produced dissociation of memory. The number of conditioning trials was also manipulated, but this variable had no significant effect on the conditioned responses. In a second experiment, ethanol injections were given again shortly before testing. This treatment caused a normal degree of conditioned drinking suppression in rats conditioned in the ethanol state, indicating that state-dependent learning was responsible for the conditioned response deficit seen in the first experiment. The dissociation was asymmetrical since rats injected with ethanol before testing only showed a high degree of conditioned suppression.

ChemInform Abstract: SPECTROSCOPIC STUDY OF MICHLER′S KETONE. PART 1. ABSORPTION

It is shown that the near ultraviolet absorption band of Michler's ketone covers three electronic transitions. There are two ππ* transitions, an intense one polarized perpendicular to the dipole moment and a weaker one at higher energy polarized parallel to the dipole moment, and an nπ* transition polarized parallel to the dipole moment. For the ππ* transitions the change of dipole moment upon excitation has been determined as 5.8 ± 0.5 and 3 ± 1 Debye, respectively. Whereas the nπ* state appears to be the first excited singlet state in non-polar media, it becomes the third excited singlet state in ethanol. The change of the absorption spectrum with temperature is discussed.

Spectroscopic study of Michler's ketone. Part 1.—Absorption

It is shown that the near ultraviolet absorption band of Michler's ketone covers three electronic transitions. There are two ππ* transitions, an intense one polarized perpendicular to the dipole moment and a weaker one at higher energy polarized parallel to the dipole moment, and an nπ* transition polarized parallel to the dipole moment. For the ππ* transitions the change of dipole moment upon excitation has been determined as 5.8 ± 0.5 and 3 ± 1 Debye, respectively. Whereas the nπ* state appears to be the first excited singlet state in non-polar media, it becomes the third excited singlet state in ethanol. The change of the absorption spectrum with temperature is discussed.

Volume Viscosity and Structure of Ethanol by Ultrasonics

A modified two-state model has been assumed in order to investigate the temperature dependence of adiabatic volume viscosities ${\ensuremath{\eta}}_{v}$,${\ensuremath{\eta}}_{v}^{\ensuremath{'}}$, and mole fraction ${x}_{2}$ in the antiparallel dipole state in ethanol. The results show that about 90% of ethanol molecules are in the higher free-energy state.