Proportion Of Ethanol Research Articles

Optimization of antioxidants and tyrosinase inhibitory activity in mango peels using response surface methodology

The aim of this study is to use a Response Surface Methodology (RSM) to optimize the ethanolic extraction of polyphenol compounds from mango peels. The Nam-Dokmai peel (NDP) showed significantly higher phenolic compounds and tyrosinase inhibitory activity than that of the Tong-Dam peel (TDP) (p < 0.05). A solid-to-liquid ratio of 1:30 was fixed for the RSM. The independent processing variables applied to the RSM were the ethanol concentrations, temperatures, and extraction times. The results show that the second-order polynomial models derived from the responses correlated well with the experimental data (R2 > 0.80). The ethanol concentrations and temperature variables significantly affected antioxidant activities (p < 0.05). A low ethanol concentration and a high temperature produced an increased yield while high ethanol concentration and high temperature was the most effective for increasing extractable phenolic content (EPC) and antioxidative activities. Therefore, the optimal conditions that maximized the extraction yields, EPC, and the antioxidant activities for NDP were ethanol proportion of 49%, a temperature of 61 °C, and an extraction time of 221 min.

Development and characterization of dialdehyde xanthan gum crosslinked gelatin based edible films incorporated with amino-functionalized montmorillonite

The amino-functionalized montmorillonite (NH2-MMT) with different amino content is successfully prepared by adjusting the solvents proportion of anhydrous ethanol and toluene. Then NH2-MMT is incorporated into gelatin to prepare composite edible films using dialdehyde xanthan gum (DXG) as the crosslinking agent. The XRD studies indicate that the amino-functionalization is beneficial for MMT to disperse and exfoliate in gelatin matrix and the incorporation of NH2-MMT can induce gelatin molecules to renature into triple-helix structure. The amino-functionalization of MMT provides active sites for the crosslinking by Schiff's base reaction to produce compact networks among gelatin, NH2-MMT and DXG. Moreover, the increase of amino content of NH2-MMT consequentially improves the crosslinking density of the composite films. Hence, the UV light barrier property, water resistance, mechanical property and thermal stability of the composite films are improved with the addition of NH2-MMT and increase along with the increase of amino content of NH2-MMT. The study demonstrates that NH2-MMT is an ideal filler for gelatin based composite edible films.

A Means of Establishing and Justifying Binary Ethanol/Water Mixtures as Simulating Solvents in Extractables Studies.

Ethanol/water mixtures are frequently used as simulating solvents in extractables studies. However, the basis for determining and justifying the right ethanol proportion in a simulating solvent for a particular drug product or solution has not been previously established.A solvent strength model has been developed in this study, based on the correlation between the levels of a model compound, di-(2-ethylhexyl) phthalate (DEHP), extracted from a reference source material, plasticized poly-(vinyl chloride) (PVC) resin, and the proportion of ethanol in ethanol/water extractions solvents. This model was established by experimentally investigating DEHP leaching and takes the form: [Formula: see text] If the level of DEHP extracted from the standard source PVC resin by a drug product is measured, then the level can be input into the above equation and the proper ethanol content of the appropriate simulating solvent can be determined.The model has been applied to certain drug products and additives used in drug products, and the proper ethanol/simulating solvents for these products have been established. Additionally, the leaching behavior revealed in this study has been established to be consistent with previously published research and a mechanism for the observed behavior has been proposed. Although ethanol/water mixtures are frequently used as simulating solvents in extractables studies, it is difficult to establish and justify what the right proportion of ethanol is for a particular drug product. A solvent strength model has been developed based on the leaching behavior of a model compound, di-(2-ethylhexyl) phthalate (DEHP), from a reference source material, plasticized poly-(vinyl chloride) (PVC). By measuring the level of DEHP leached into a drug product from the reference source material, one can use the model to calculate the correct ethanol proportion in the simulating solvent.Using this approach, ethanol/water proportions have been obtained for certain drug products. Additionally, the leaching profiles for DEHP obtained in this study were noted to be consistent with such profiles for other extractables from the PVC reference source material and with other investigations of ethanol/water as model stimulants.

Life cycle environmental sustainability of lignocellulosic ethanol produced in integrated thermo‐chemical biorefineries

AbstractThere is a growing interest in producing biofuels and bio‐chemicals from lignocellulosic feedstocks in integrated biorefineries. However, the sustainability implications of integrated biorefineries are still poorly understood. Using a life cycle approach, this paper examines environmental impacts of second‐generation ethanol produced in thermo‐chemical refineries together with chemicals and energy. Four feedstocks are considered: wheat straw, poplar, Miscanthus and forest residue. The results suggest that the production of ethanol from these feedstocks offers significant savings in eight out of 12 environmental impacts when the system is credited for the avoided impacts from producing the co‐products from fossil resources. Ethanol from forest residue is the best and wheat straw the worst option for most impacts. Land use change has a significant effect on the global warming potential (GWP) of ethanol. For example, conversion of forest to grow Miscanthus increases the GWP from –234 to 6685 g CO2 eq./l of ethanol. The effect is opposite when grassland is converted to grow poplar: the GWP is reduced by two times because of carbon sequestration by poplar. The thermo‐chemical route for producing ethanol from poplar and forest residue is more sustainable for most impacts than the bio‐chemical conversion with the same feedstocks. Although ethanol saves up to 83% of GHG emissions per MJ of fuel compared to petrol, the savings are much smaller (~3%) for current ethanol blends of 5%. Therefore, unless a much higher proportion of ethanol was used, the contribution of second‐generation ethanol to climate change mitigation would be small. © 2015 The Authors. Biofuels, Bioproducts, Biorefining published by Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

(Invited) Electrochemical CO2 Reduction to Formic Acid on Crystalline SnO2 Nanosphere Catalyst

In this work, the morphology controlled SnO2 nanosphere catalyst has been successfully synthesized and applied to electrochemical CO2 reduction to formic acid in 0.5 M KHCO3. The catalysts were synthesized by a simple hydrothermal method under controlling the different proportions of ethanol to distilled water as mixed solvent. The obtained catalysts were then coated on gas diffusion electrode (SnO2/GDE) as working electrode. It was found that the catalyst prepared from 50% content of ethanol gives the best catalytic activity towards CO2 reduction, where the onset potential was found to be 300 mV more anodic than that of hydrogen evolution. Meanwhile, the SnO2/GDE-50 showed the most stable property for CO2 reduction. The current density and faradaic efficiency increased as the potential increased, reaching a maximum at -1.7 V vs. SHE. At this stage, the maximum faradaic efficiency of 68% with a current density of 6 mA cm-2 was obtained. Moreover, the production rate of format exhibits a maximum value of 518.2 mg L-1 at the cathode potential of -1.9 V vs. SHE.

Spray-dried amikacin sulphate powder for inhalation in cystic fibrosis patients: The role of ethanol in particle formation

A Central Composite Design (CCD) was applied in order to identify positive combinations of the production parameters of amikacin sulphate spray-dried powders for inhalation, with the intent to expand the experimental space defined in a previous half-fractional factorial design. Three factors, namely drying temperature, feed rate and ethanol proportion, have been selected out of the initial five. In addition, the levels of these factors were increased from two to three and their effect on amikacin respirability was evaluated. In particular, focus was given on the role of ethanol presence on the formation of the microparticles for inhalation.The overall outcome of the CCD was that amikacin respirability was not substantially improved, as the optimum region coincided with areas already explored with the fractional factorial design. However, expanding the design space towards smaller ethanol levels, including its complete absence, revealed the crucial role of this solvent on the morphology of the produced particles. Peclet number and drug solubility in the spraying solution helped to understand the formation mechanism of these amikacin sulphate spray-dried particles.

Optimization of Total Phenolic from &lt;i&gt;Cleistocalyx nervosum&lt;/i&gt; by Microwave-Assisted Extraction

The objective of this research was to extract phenolic compounds from Makiang (Cleistocalyx nervosum) seeds waste obtained from the elaboration of makiang beverages using the microwave assisted extraction method. The optimal conditions of microwave assisted extraction of total phenolics from makiang seeds were determined using response surface method. The variables of microwave power, extraction time and ethanol proportion on effect of total phenolic were designed the experiment by Box Behnken design. The estimation of the mathematical model indicated that the second-order polynomial model was appropriate to determine optimal conditions of microwave assisted extraction of total phenolics from makiang seeds. The highest yield of total phenolic from makiang seed and antioxidant activity were obtained when the extraction process was set at a microwave power, 450 W, an extraction time of 213 second and an ethanol proportion of 51%(v/v). Under these optimal conditions, the predicted and experimental values of total phenolic from makiang seeds were the 75.659 mgGAE/gDW and 75.132±0.576 mgGAE/gDW, respectively. The research showed that total phenolics from makiang seeds by microwave assisted extraction have the high efficiency in terms of high yield and antioxidant activity within short time extraction which can apply to use in cosmetic product, health food and pharmaceutical industry.

Improving surface and mechanical properties of alginate films by using ethanol as a co-solvent during external gelation

Alginate films were prepared by solution casting method and further ionically crosslinked in a calcium chloride (CaCl2) water solution containing different proportions (0–40% v/v) of ethanol as the co-solvent. The addition of ethanol into the CaCl2 water solution was found to improve the visual appearance, thickness, surface homogeneity, and mechanical properties of the films, which can be attributed to the reduced swelling degree of films during crosslinking process. Furthermore, Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDS) analysis indicated that the incorporation of ethanol into the crosslinking solution did not detract from the uniformity of crosslinking throughout the film matrix. However, the swelling degree and calcium content determination indicated that the Ca2+ crosslinking degree decreased when the ethanol proportion exceeded 30% v/v. Consequently, this study introduces a green, efficient, and simple technique for the preparation of calcium alginate films with excellent surface appearance and mechanical properties for pharmaceutical products.

A Facile Method for Controllable Fabrication of Porous Anodic Aluminum Oxide Templates with Multiple-Scale Structures

Porous anodic aluminum oxide (AAO) templates with diverse nano/submicron/micron multiple-scale structures have been fabricated by a facile and controllable two-step anodization process. The first step anodization has been achieved by using a simple competitive growth process with high anodization voltage (Ua) in ethanol-oxalic acid mixture electrolytes. The effects of Ua (300–600 V), anodization current density (Ja, 100–200 A m−2), and the proportion of ethanol adding (0.3 M oxalic acid : ethanol = 1 : 1, 3 : 2, V/V) on the submicron/micron structures of AAO templates have been investigated in detail. The second step anodization has been conducted under relatively lower Ua of 30 V and 40 V, respectively. The effects of Ua, etching process, and anodization time on the nanostructures of as-fabricated porous AAO templates have been studied carefully. In addition, related intrinsic formation mechanisms have also been investigated. Based on these quantitative experimental results, the fabrication of multiple-scale porous AAO films with diverse nano/submicron/micron structures can be more controllable and designable, facilitating their practical applications in simple template synthesis of complex multiple-scale functional materials.

Modification of Diesohol Fuel Properties by Using Cashew Nut Shell Liquid and Biodiesel as Additives

AbstractIn this research, modified diesohol blends were characterized with cashew nut shell liquid (CNSL) and biodiesel as additives. Different proportions of CNSL, diesel, and ethanol were prepared to study the properties of the fuel blends such as viscosity, heating value, acid value, and cetane index. The minimum threshold limit of 6 % by volume of CNSL provided a stable mixture. The viscosity increased slightly with increasing CNSL content whereas the heating value was not significantly affected. All of the fuel blends did not meet the fuel standard in terms of the acid value. Biodiesel was used as a substitute for a fraction of CNSL to lower the acid value. The final fuel blend was DE20 (diesohol with 20 % ethanol content) with 0.5 % CNSL and 12 % biodiesel (by volume). The acid value, viscosity, and heating value were 0.78 mg(KOH) g−1, 2.69 cSt, and 40.11 MJ kg−1, respectively. The economic analysis showed that the ex‐refinery and retail prices of the fuel blend were 22.83 and 28.32 baht L−1, respectively (≈32 Thai baht=$1 US, with the current exchange rates).

Maturation of biomass‐to‐biofuels conversion technology pathways for rapid expansion of biofuels production: a system dynamics perspective

AbstractThe Biomass Scenario Model (BSM) is a system‐dynamics simulation model intended to explore the potential for rapid expansion of the biofuels industry. The model is not predictive — it uses scenario assumptions based on various types of data to simulate industry development, emphasizing how incentives and technological learning‐by‐doing might accelerate industry growth. The BSM simulates major sectors of the biofuels industry, including feedstock production and logistics, conversion, distribution, and end uses, as well as interactions among sectors. The model represents conversion of biomass to biofuels as a set of technology pathways, each of which has allowable feedstocks, capital and operating costs, allowable products, and other defined characteristics. This study and the BSM address bioenergy modeling analytic needs that were identified in recent literature reviews. Simulations indicate that investments are most effective at expanding biofuels production through learning‐by‐doing when they are coordinated with respect to timing, pathway, and target sector within the biofuels industry. Effectiveness metrics include timing and magnitude of increased production, incentive cost and cost effectiveness, and avoidance of windfall profits. Investment costs and optimal investment targets have inherent risks and uncertainties, such as the relative value of investment in more‐mature versus less mature pathways. These can be explored through scenarios, but cannot be precisely predicted. Dynamic competition, including competition for cellulosic feedstocks and ethanol market shares, intensifies during times of rapid growth. Ethanol production increases rapidly, even up to Renewable Fuel Standards‐targeted volumes of biofuel, in simulations that allow higher blending proportions of ethanol in gasoline‐fueled vehicles. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. Biofuels, Bioproducts, Biorefining published by John Wiley &amp; Sons, Ltd on behalf of Society of Chemical Industry.

Mesoporous silica-coating of gold nanorods by a templated method

Mesoporous silica with tunable morphology, pore architecture and crystallinity was successfully coated on gold nanorods by a template method based on the self-assembly of anionic surfactants with inorganic precursors. Varying the molar ratio of acid to surfactant or the volume ratio of ethanol to water resulted in products with different shapes, ranging from rods to spherical particles. A phase transformation of the mesoporous silica shell from 2D hexagonal to 3D cubic occurred due to an increased acid/surfactant ratio. Increasing the proportion of ethanol also gradually caused the disappear of 2D hexagonal symmetry of silica. The charge density matching relationship and solution polarity induced by varied reaction composition are believed to be the driving forces for the change of morphology and mesostructure.

Optimized microwave-assisted extraction of 6-gingerol from Zingiber officinale Roscoeand evaluation of antioxidant activity in vitro.

6-Gingerol is one of the most pharmacologically active and abundant components in ginger, which has a wide array of biochemical and pharmacologic activities. In recent years, the application of microwave-assisted extraction (MAE) for obtaining bioactive compounds from plant materials has shown tremendous research interest and potential. In this study, an efficient microwave-assisted extraction (MAE) technique was developed to extract 6-gingerol from ginger. The extraction efficiency of MAE was also compared with conventional extraction techniques. Fresh gingers (Zingiber officinale Rose.) were harvested at commercial maturity (originally from Shandong, laiwu, China). In single-factor experiments for the recovery of 6-gingerol, proper ranges of ratio of liquid to solid, ethanol proportion, microwave power, extraction time were determined. Based on the values obtained in single-factor experiments, a Box-Behnken design (BBD) was applied to determine the best combination of extraction variables on the yield of 6-gingerol. The optimum extraction conditions were as follows: microwave power 528 W, ratio of liquid to solid 26 mL·g(-1), extraction time 31 s and ethanol proportion 78%. Furthermore, more 6-gingerol and total polyphenols contents were extracted by MAE than conventional methods including Maceration (MAC), Stirring Extraction (SE), Heat reflux extraction (HRE), Ultrasound-assisted extraction (UAE), as well as the antioxidant capacity. Microwave-assisted extraction showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract within shortest extraction time. Scanning electron microscopy (SEM) images of ginger powder materials after different extractions were obtained to provide visual evidence of the disruption effect. To our best knowledge, this is the first report about usage of MAE of 6-gingerol extraction from ginger, which could be referenced for the extraction of other active compounds from herbal plants.

Characteristics of wheat straw lignins from ethanol-based organosolv treatment

Non-purified lignins resulting from ethanol-based organosolv fractionation of wheat straw were characterized for the presence of impurities (carbohydrates and ash), functional groups (hydroxyl, carboxyl and methoxyl), phenyl-propanoid structural moieties, molar mass distribution and thermal behavior. In accordance with its herbaceous nature, the syringyl/guaiacyl-ratio of the wheat straw lignins was substantially lower than of Alcell lignin. In addition, the content of p-hydroxyphenyl and carboxyl groups is substantially higher for the wheat straw lignins. The non-purified organosolv lignins had a high purity with 0.4–5.2% carbohydrate impurities, both originating from lignin to carbohydrate complexes and residual organosolv liquor. The use of H2SO4 in the organosolv process improved the lignin yield, but at low acid doses increased the carbohydrate impurities. For applications where a low amount of carbohydrates is important, lignin from a high-temperature autocatalytic organosolv process was found to be preferred. The highest content of total hydroxyl groups was determined when lignins were produced using 30mM H2SO4 as catalyst or 50% w/w aqueous ethanol as solvent for the organosolv process. Aliphatic hydroxyl groups, the most predominant type of hydroxyl groups present originating for a substantial part from residual carbohydrates, were found to decrease with reaction time and ethanol proportion of the organosolv solvent. The correlations between organosolv process conditions and lignin characteristics determined can facilitate the use of organosolv lignins in value-added applications such as in polymers and resins and as a feedstock for bio-based aromatics.

Solvent, drying time, and substrate affect the responses of lone star ticks (Acari: Ixodidae) to the repellents deet and picaridin.

Behavioral bioassays remain a standard tool in the discovery, development, and registration of arthropod repellents. Tick repellent bioassays are generally uncomplicated, but their results can be affected by basic variables (e.g., dimensions of testing materials, substrate, timing, temperature) of the assay. Using lone star tick, Amblyomma americanum (L.), nymphs in climbing bioassays, we tested for the effects of substrate, solvent, and drying time on tick responses. In dose-response tests, the widely used repellents N,N-diethyl-3-methyl benzamide (deet) and 1-methyl-propyl-2-(hydroxyethyl)-1-piperidinecarboxylate (picaridin) were applied to filter paper strips and challenged by ticks at 10, 20, 30, 40, and 120 min after application. At 10-min drying time, repellency at the intermediate concentration 500 nmol repellent/cm2 filter paper was significantly lower for ethanol solutions of deet and picaridin (0 and 10% ticks repelled, respectively) than for solutions of deet and picaridin in acetone (96.7 and 76.7% ticks repelled, respectively). Repellency was greatest for both the acetone and ethanol solutions of deet and picaridin when challenged 120 min after application, and at shorter drying times at the highest concentration tested (2,000 nmol compound/ cm2). The repellency of picaridin relative to deet differed at some combinations of solvent and drying time but not others. In dose-response tests using different paper substrates and a drying time of 10 min, both ethanol and acetone solutions of deet differed in repellency, depending on both the paper substrate and the solvent. However, there were no differences in repellency between ethanol and acetone solutions of deet applied to nylon organdy in an in vitro and in an in vivo (fingertip) bioassay. When deet in solution with various proportions of ethanol:water was applied at 2,000 nmol deet/cm2 filter paper, the proportion of ticks repelled decreased as the proportion of water in the test solutions increased. Somewhat similar results were seen for solutions of deet in an acetone solvent. Water absorbed from the atmosphere may affect the efficacy of repellents in solution with anhydrous ethanol. Overall, results obtained from bioassays that differ in seemingly minor ways can be surprisingly different, diminishing the value of comparing studies that used similar, but not identical, methods. Nylon organdy or another similar thin cloth may be preferable to filter papers and copier paper for minimizing solvent-related differences. When a paper substrate is used, acetone may be the more suitable solvent if the solubility of the test compound and other factors allow.

Determination of antioxidant activity and phenolic content of extracts from in vivo plants and in vitro materials of Passiflora alata Curtis

Passiflora alata Curtis, commonly known as sweet passion fruit, is one of the commercially cultivated species of the genus Passiflora, whose fruits can be consumed in natura due to their sweet taste. It is also used worldwide as an ornamental and in folk medicine. The goal of this work was the evaluation of the antioxidant potential of extracts from in vivo plants, and in vitro-derived materials of P. alata. Leaves from in vivo plants were used for the optimization of parameters that affect the efficiency of extraction of antioxidant compounds (proportions of ethanol:water, maceration period, solvent:plant tissue ratio, and number of extraction stages), by employing the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The antioxidant activity and the extract yields were significantly influenced by the proportion of ethanol:water and maceration period. The optimized protocol was applied to obtain the extracts of in vitro-derived materials. Total phenolic content was determined using the Folin–Ciocalteu method. Higher antioxidant activities and phenolic contents were observed in extracts from leaves of in vivo-seed derived and from acclimatized plants when compared to in vitro plants, calluses and suspension cultures. Differences in the reaction kinetics of DPPH scavenging activity were also observed.

Jojoba ethyl ester production and properties of ethanol blends

This research aims to study the possibility of using jojoba ethyl ester (JEE), and its blends with ethanol in diesel engines. The physical and chemical properties of the jojoba ethyl ester and its blends with ethanol in different ratios (5%, 10%, 15% and 20% ethanol by volume) have been measured. The following properties have been measured for the tested fuels: viscosity, density, low calorific value, flash point, pour point, cetane index, total acid number, total base number, sulfur content, and ash content. The method of preparation of JEE by transesterification process is optimized to find the lowest proportion of ethanol that gives the best properties of ester. It has been shown that using 7% ethanol gives the highest yield of ester, taking into account the cost. Blending more ethanol with JEE resulted in the decrease of density, pour point, and low calorific value. There is a need for future researches to reduce the pour point of (JEE) and its blends with ethanol. JEE and its blends with ethanol is a promising biofuel, which can be used in diesel engines.

Experimental Investigation on Biodiesel-Ethanol-Diesel Blends Operating with a Diesel Engine

Biodiesel is an alternative, decomposable and biological-processed fuel that has similar characteristics with mineral diesel which can be used directly into diesel engines. However, biodiesel has its drawbacks which are more density and viscosity compared to mineral diesel. Alcohol additives implementation such as ethanol could reduce significantly the density and viscosity of the biodiesel. In this study, biodiesel (20%)-ethanol (5%)-diesel (75%), biodiesel (20%)-methanol (10%)-diesel (70%), biodiesel (20%)-ethanol (15%)-diesel (65%), biodiesel (20%)-ethanol (20%)-diesel (60%) and standard mineral diesel as a baseline fuel are tested in a Mitsubishi 4D68 diesel engine. Those test fuels are investigated under the same operating conditions at three different engine loads; 20%, 40% and 60% at a constant engine speed of 2500 rpm to determine the engine performance, combustion and emission of the diesel engine. Overall, biodiesel-ethanol-diesel blends show higher brake specific fuel consumption than mineral diesel especially at higher ethanol concentration. As ethanol proportions in blends increase, CO emissions increase, while NO emissions are reduced. Also, biodiesel-ethanol blend with 5% ethanol is more effective than other biodiesel-ethanol blends for reducing CO emissions and improve the combustion.

Effects of Ethanol-n butanol-diesel Oxygenated Fuel on Performance of Diesel Engine

The experiments of the economy performance and emissions of diesel engine fueled with ethanol-n butanol-diesel were performed on a dual-cylinder direct injection diesel engine. The results show that without modification on the engine, while the mixed proportion of ethanol getting larger, the equivalent brake specific fuel consumption decreases and effective thermal efficiency increases when the diesel engine work on medium and high loads condition, NOX emissions and smoke decreased obviously. But the smoke increased when the proportion of ethanol is 20%. And the results also indicate that it is beneficial for decreasing the smoke and NOX emissions to reduce suitably fuel supply advance angle when the diesel engine fueled with blend fuel mixed high proportion of ethanol.

Kinetic study of specific base catalyzed hydrolysis of ethyl acrylate in water-ethanol binary system

Kinetic study of hydroxide anion catalyzed hydrolysis of ethyl acrylate has been carried in ethanol-water (10–50% v/v) binary systems at the temperature range 30 ± 0.1, 35 ± 0.1, 40 ± 0.1, and 45 ± 0.1°C. Calculated specific rate constant values decreases with increasing proportion of ethanol at all temperatures. The observed retardation of a base catalyzed hydrolysis reaction is explained on the basis of fact that the formation of polarized transition state is disfavored with increase in % of ethanol. The relation between the change in dielectric constant due to variation in binary mixtures and change in specific rate constant are explained on the basis of electrostatic and non electrostatic contributions of solvent mixtures. The variation of ΔG*, ΔH*, ΔS* with solvent composition and the specific effect of water on the reaction rate kinetics are also discussed.