Short-chain Alcohols Research Articles

Glycerol and Catalysis by Waste/Low-Cost Materials—A Review

The growing global demand for renewable energy sources can be reached using biofuels such as biodiesel, for example. The most used route to produce biodiesel is the transesterification reaction of oils or fats with short-chain alcohols, generating fatty acid esters (biodiesel) and a very important by-product, glycerol (Gly). Gly is widely used in different sectors of the industry, and in order to add value to this by-product, heterogeneous catalysis becomes a relevant tool, whether to transform glycerol into other chemical products of interest or even use it in the production of catalysts. Among the several studies found in the literature, the use of low-cost materials and/or wastes from the most diverse activities to prepare active catalytic materials for the transformation of Gly has been increasingly reported due to its valuable advantages, especially related to the cost of raw materials and environmental aspects. Thus, this brief review article presents the relationship between catalysis, low-cost materials, waste, and glycerol, through different studies that show glycerol being transformed through reactions catalyzed by materials produced from low-cost sources/waste or with the glycerol itself used as a catalyst.

Quantifying local pH changes in carbonate electrolyte during copper-catalysed hbox {CO}_2 electroreduction using in operando^{13}hbox {C} NMR

The electrochemical carbon dioxide reduction on copper attracted considerable attention within the last decade, since Cu is the only elemental transition metal that catalyses the formation of short-chain hydrocarbons and alcohols. Research in this field is mainly focused on understanding the reaction mechanism in terms of adsorbates and intermediates. Furthermore, dynamic changes in the micro-environment of the catalyst, i.e. local pH and hbox {CO}_2 concentration values, play an equivalently important role in the selectivity of product formation. In this study, we present an in operando^{13}hbox {C} nuclear magnetic resonance technique that enables the simultaneous measurement of pH and hbox {CO}_2 concentration in electrode vicinity during electroreduction. The influence of applied potential and buffer capacity of the electrolyte on the formation of formate is demonstrated. Theoretical considerations are confirmed experimentally and the importance of the interplay between catalyst and electrolyte is emphasised.

Design-Based Response Surface Methodology in Optimizing the Dry Washing Purification Process of Biodiesel from Waste Cooking Oil

Biodiesel is an alternative renewable energy source derived from plants or animals. It reduces greenhouse gas emissions mostly caused by fossil fuels and threatens the environment. Furthermore, biodiesel is clean energy from a mixture of fatty acids and short-chain alcohols, such as esters, produced from oil waste through the transesterification and purification of the dry washing process using magnesium silicate hydrate. This study designed the Response Surface Methodology with the Box Behnken Design consisting of 3 independent variables, namely magnesium silicate hydrate concentration, temperature, and production time required to predict the optimum conditions of biodiesel. This result showed that the biodiesel produced is 85-94.50% with a minimum yield of 85.171% at a 1.6748% adsorbent concentration, 65℃ operating temperature, and 10 minutes. Furthermore, the validation result with the T-Test is achieved by an average of 85.01%.

Specific Detection of Short-Chain Alcohols, with the Development of an Enzyme-Coated Microcantilever-Based Biosensor

Specific Detection of Short-Chain Alcohols, with the Development of an Enzyme-Coated Microcantilever-Based Biosensor

Tuning Contact Angles of Aqueous Droplets on Hydrophilic and Hydrophobic Surfaces by Surfactants.

Adsorption of small amphiphilic molecules occurs in various biological and technological processes, sometimes desired while other times unwanted (e.g., contamination). Surface-active molecules preferentially bind to interfaces and affect their wetting properties. We use molecular dynamics simulations to study the adsorption of short-chained alcohols (simple surfactants) to the water–vapor interface and solid surfaces of various polarities. With a theoretical analysis, we derive an equation for the adsorption coefficient, which scales exponentially with the molecular surface area and the surface wetting coefficient and is in good agreement with the simulation results. We apply the outcomes to aqueous sessile droplets containing surfactants, where the competition of surfactant adsorptions to both interfaces alters the contact angle in a nontrivial way. The influence of surfactants is the strongest on very hydrophilic and hydrophobic surfaces, whereas droplets on moderately hydrophilic surfaces are less affected.

Thermodynamic properties of binary systems containing 1-allyl-3-methylimidazolium dicyanamide [Amim][DCA] with short chain alcohols and prediction of surface tension based on molar surface Gibbs free energy

BackgroundAllyl functionalized ionic liquids (ILs) are widely used because of their excellent properties, to increase their applications in industry and academic community, preparing binary mixtures containing ILs and organic solvents is an effective way, and it is essential to further explore the thermodynamic properties of them. MethodsHere, we reported the synthesis and characterization of the ILs 1-allyl-3-methylimidazolium dicyanamide [Amim][DCA]. Then, in the temperature range of 288.15 K–318.15 K, the values of density and surface tension of 1-allyl-3-methylimidazolium dicyanamide, methanol, ethanol, propanol and corresponding binary systems were measured at every 5 K in the full molar concentration. The values of surface tension deviation Δγ, excess molar volume VE and molar surface Gibbs free energy gs of the mixtures were calculated. In addition, the modified Eӧtvӧs equation is derived based on gs, and the values of surface tension of binary mixtures are estimated. Significant findingsThe results show VE are negative, which is mainly due to the tight packing and hydrogen bond, the formation of hydrogen bond has been confirmed by infrared spectroscopy. The Δγ values of 1-allyl-3-methylimidazolium dicyanamide + methanol are positive, while that of the other two are negative. The modified Eӧtvӧs equation has a clear physical meaning. Moreover, the predicted values are in good agreement with the measured ones.

Enantiomeric separation of newly synthesized amino, thio, and oxy derivatives of monoterpene lactones, amides, and ester applying polysaccharide-based chiral stationary phases in normal-phase mode

New amino, thio, and oxy derivatives of monoterpene lactones, amides, and esters have been synthesized and their enantioselective separations were investigated on seven covalently immobilized polysaccharide-based chiral stationary phases. The effects of basic additives, different short-chain alcohols, and the influence of the temperature on the chromatographic behavior were studied. In addition, relationships between the structure of selector and selectand and the chromatographic parameters were explored to reveal mechanistic details of chiral recognition. Experiments were performed in the temperature range 10–50°C and thermodynamic parameters were calculated from plots of lnα versus 1/T. The separations were generally enthalpy-controlled, but entropy-driven separation was also observed. Special attention has been paid to the enantiomer elution order and several examples are shown how the structural characteristics of the selector, the nature, and the concentration of the polar modifier induce reversal of the enantiomer elution order in the case of the polysaccharide-based selectors.

Determining the double-bond positions of monounsaturated compounds in the alcohol fraction in seep carbonate

The unsaturation patterns of molecular fossils are critical in distinguishing their biological precursors and diagenetic processes. However, questions regarding the determination of double-bond positions of unsaturated dialkyl glycerol ethers (DAGEs) in submarine hydrocarbon seep ecosystems remain unsolved. To address this problem, a protocol for dimethyl disulfide (DMDS) derivative analysis using gas chromatography (GC)-mass spectrometry was optimised. Herein, the double-bond positions of monounsaturated short-chain alcohols, monoalkyl glycerol ethers (MAGEs), and DAGEs in seep carbonates were analysed. Among these compounds, the double-bond positions of trimethylsilyl (TMS) derivatives of the monounsaturated DAGE-DMDS adducts were determined for the first time, with mass spectra characterized by molecular ions (M+·) and two major diagnostic ions (ω+ and Δ+) cleaved at the double bonds. For both the MAGEs and DAGEs, the double-bond positions of the monounsaturated n-C16:1-alkyl moieties were identified at ω5 and ω7. Compared to monounsaturated short-chain alcohols and MAGEs, both ionization efficiency and relative sensitivity for the TMS derivatives of DAGE-DMDS adducts were low as indicated by the high limit of detection at a signal-to-noise ratio of 3. In addition, the appropriate injection parameters and oven temperature program during GC analyses may be crucial in determining the double-bond positions within monounsaturated DAGEs.

A Novel Approach for Monitoring the Volatile Metabolome in Biological Samples from Ruminants through Miniaturized Liquid-Liquid Extraction and Multiclass Gas Chromatography Analysis.

A straightforward and versatile methodology for the extraction of volatile metabolites in biological samples from ruminants for gas chromatography analysis is proposed. The methodology was applied in the determination of multiclass metabolites (short-chain fatty acids, aldehydes, alcohols, ketones, esters, phenols, and sulfides) in different analytical matrices (rumen fluid, urine, and feces) collected from Holstein cows. The 24 multiclass volatile metabolites reported in the different biological samples and their respective concentrations were critically discussed in the context of digestive physiology. Most detected compounds are derived from the rumen and lower gut fermentation of carbohydrates, proteins, and lipids or their metabolism, being consistent with the prior state of the art. The proposed method also takes advantage of the already existing tools in animal nutrition laboratories, providing a novel methodological ground that can generate relevant bioanalytical information with a significant impact on ruminant's nutritional studies.

Alkanes as Membrane Regulators of the Response of Early Membranes to Extreme Temperatures.

One of the first steps in the origin of life was the formation of a membrane, a physical boundary that allowed the retention of molecules in concentrated solutions. The proto-membrane was likely formed by self-assembly of simple readily available amphiphiles, such as short-chain fatty acids and alcohols. In the commonly accepted scenario that life originated near hydrothermal systems, how these very simple membrane bilayers could be stable enough in time remains a debated issue. We used various complementary techniques such as dynamic light scattering, small angle neutron scattering, neutron spin-echo spectroscopy, and Fourier-transform infrared spectroscopy to explore the stability of a novel protomembrane system in which the insertion of alkanes in the midplane is proposed to shift membrane stability to higher temperatures, pH, and hydrostatic pressures. We show that, in absence of alkanes, protomembranes transition into lipid droplets when temperature increases; while in presence of alkanes, membranes persist for longer times in a concentration-dependent manner. Proto-membranes containing alkanes are stable at higher temperatures and for longer times, have a higher bending rigidity, and can revert more easily to their initial state upon temperature variations. Hence, the presence of membrane intercalating alkanes could explain how the first membranes could resist the harsh and changing environment of the hydrothermal systems. Furthermore, modulating the quantity of alkanes in the first membranes appears as a possible strategy to adapt the proto-membrane behavior according to temperature fluctuations, and it offers a first glimpse into the evolution of the first membranes.

Critical role for isoprenoids in apicoplast biogenesis by malaria parasites.

Isopentenyl pyrophosphate (IPP) is an essential metabolic output of the apicoplast organelle in Plasmodium falciparum malaria parasites and is required for prenylation-dependent vesicular trafficking and other cellular processes. We have elucidated a critical and previously uncharacterized role for IPP in apicoplast biogenesis. Inhibiting IPP synthesis blocks apicoplast elongation and inheritance by daughter merozoites, and apicoplast biogenesis is rescued by exogenous IPP and polyprenols. Knockout of the only known isoprenoid-dependent apicoplast pathway, tRNA prenylation by MiaA, has no effect on blood-stage parasites and thus cannot explain apicoplast reliance on IPP. However, we have localized an annotated polyprenyl synthase (PPS) to the apicoplast. PPS knockdown is lethal to parasites, rescued by IPP and long- (C50) but not short-chain (≤C20) prenyl alcohols, and blocks apicoplast biogenesis, thus explaining apicoplast dependence on isoprenoid synthesis. We hypothesize that PPS synthesizes long-chain polyprenols critical for apicoplast membrane fluidity and biogenesis. This work critically expands the paradigm for isoprenoid utilization in malaria parasites and identifies a novel essential branch of apicoplast metabolism suitable for therapeutic targeting.

Short-chain alcohols inactivate an immobilized industrial lipase through two different mechanisms.

Broadly used in biocatalysis as acyl acceptors or (co)-solvents, short-chain alcohols often cause irreversible loss of enzyme activity. Understanding the mechanisms of inactivation is a necessary step toward the optimization of biocatalytic reactions and the design of enzyme-based sustainable processes. The functional and structural responses of an immobilized enzyme, Novozym 435 (N-435), exposed to methanol, ethanol, and tert-butanol, are explored in this work. N-435 consists of Candida antarctica lipase B (CALB) adsorbed on polymethacrylate beads and finds application in a variety of processes involving the presence of short-chain alcohols. The nature of the N-435 material required the development of an ad hoc method of structural analysis, based on Fourier transform infrared microspectroscopy, which was complemented by catalytic activity assays and by morphological observation by transmission electron microscopy. The inactivation of N-435 was found to be highly dependent on alcohol concentration and occurs through two different mechanisms. Short-chain alcohols induce conformational changes leading to CALB aggregation, which is only partially prevented by immobilization. Moreover, alcohol modifies the texture of the solid support promoting the enzyme release. Overall, knowledge of the molecular mechanisms underlying N-435 inactivation induced by short-chain alcohols promises to overcome the limitations that usually occur during industrial processes.

Competing esterification and oligomerization reactions of typical long-chain alcohols to secondary organic aerosol formation

Organosulfate (OSA) nanoparticles, as secondary organic aerosol (SOA) compositions, are ubiquitous in urban and rural environments. Hence, we systemically investigated the mechanisms and kinetics of aqueous-phase reactions of 1-butanol/1-decanol (BOL/DOL) and their roles in the formation of OSA nanoparticles by using quantum chemical and kinetic calculations. The mechanism results show that the aqueous-phase reactions of BOL/DOL start from initial protonation at alcoholic OH-groups to form carbenium ions (CBs), which engage in the subsequent esterification or oligomerization reactions to form OSAs/organosulfites (OSIs) or dimers. The kinetic results reveal that dehydration to form CBs for BOL and DOL reaction systems is the rate-limiting step. Subsequently, about 18% of CBs occur via oligomerization to dimers, which are difficult to further oligomerize because all reactive sites are occupied. The rate constant of BOL reaction system is one order of magnitude larger than that of DOL reaction system, implying that relative short-chain alcohols are more prone to contribute OSAs/OSIs than long-chain alcohols. Our results reveal that typical long-chain alcohols contribute SOA formation via esterification rather than oligomerization because OSA/OSI produced by esterification engages in nanoparticle growth through enhancing hygroscopicity.

Numerical investigation of droplet evaporation in high-pressure dual-fuel conditions using a tabulated real-fluid model

The substitution of diesel by cleaner renewable fuels such as short-chain alcohols in dual-fuel internal combustion engines is considered an attractive solution to reduce the pollutant emissions from internal combustion engines. In this context, two-phase flow models for multi-component mixtures considering the real-fluid thermodynamics are required for further understanding the evaporation and mixing processes in transcritical conditions. The present study proposes an efficient real-fluid model (RFM) based on a two-phase, fully compressible four-equation model under mechanical and thermal equilibrium assumptions with a diffused interface and closed by a thermodynamic equilibrium tabulation approach. Compared to previous research limited to binary mixtures tabulation, the proposed pre-tabulation approach can further handle ternary mixtures using a thermodynamic table that has been coupled to the CONVERGE CFD solver. The newly developed RFM model has been applied to investigate the evaporation of an n-dodecane droplet in a mixed ambient (methanol and nitrogen) relevant to dual-fuel configuration compared to pure nitrogen ambient. The four equation model is closed by a tabulated Cubic Plus Association (CPA) and Peng–Robinson (PR) equations of state for the droplet evaporation in a mixed and single component ambient, respectively. Numerical predictions show that the n-dodecane droplet lifetime decreases monotonically with increasing the methanol ambient concentration under the considered transcritical conditions. The performed thermodynamic analysis demonstrates that the droplet follows a different thermodynamic path as a function of the methanol ambient concentration. The different mechanisms contributing to the droplet lifetime behavior under varying ambient conditions are discussed.

Topical therapy of various dermatoses with ImpoyzTM (clobetasol propionate) cream 0.025%

The most widely prescribed drugs for the treatment of a variety of dermatoses are Topical corticosteroids (TC). These medications are approved for the treatment of inflammatory and pruritic manifestations of dermatologic disorders due to their powerful symptom-relieving impact. Clobetasol propionate (CP) is the most popular (TC) used to relieve itching, redness, and oedema caused by a variety of skin disorders. Anti-inflammatory, anti-pruritic, and vasoconstrictive characteristics are all present in it. CP works by binding to cytoplasmic glucocorticoid receptors and activating glucocorticoid receptor-mediated gene expression, resulting in the production of anti-inflammatory proteins while suppressing the production of inflammatory mediators. The formulation is free from known contact allergens, such as propylene glycol, short-chain alcohols, and sorbitol-based emulsifiers, and has demonstrated hypoallergenic effects. The efficacy, safety, and clinical experience of utilizing CP 0.025% cream for the treatment of various dermatologic disorders are discussed in this case series.

Effects of COVID-19 protective face masks and wearing durations on respiratory haemodynamic physiology and exhaled breath constituents.

BackgroundWhile assumed to protect against coronavirus transmission, face masks may have effects on respiratory–haemodynamic parameters. Within this pilot study, we investigated immediate and progressive effects of FFP2 and surgical masks on exhaled breath constituents and physiological attributes in 30 adults at rest.MethodsWe continuously monitored exhaled breath profiles within mask space in older (age 60–80 years) and young to middle-aged (age 20–59 years) adults over the period of 15 and 30 min by high-resolution real-time mass-spectrometry. Peripheral oxygen saturation (SpO2) and respiratory and haemodynamic parameters were measured (noninvasively) simultaneously.ResultsProfound, consistent and significant (p≤0.001) changes in SpO2 (≥60_FFP2-15 min: 5.8±1.3%↓, ≥60_surgical-15 min: 3.6±0.9%↓, <60_FFP2-30 min: 1.9±1.0%↓, <60_surgical-30 min: 0.9±0.6%↓) and end-tidal carbon dioxide tension (PETCO2) (≥60_FFP2-15 min: 19.1±8.0%↑, ≥60_surgical-15 min: 11.6±7.6%↑, <60_FFP2- 30 min: 12.1±4.5%↑, <60_surgical- 30 min: 9.3±4.1%↑) indicate ascending deoxygenation and hypercarbia. Secondary changes (p≤0.005) to haemodynamic parameters (e.g. mean arterial pressure (MAP) ≥60_FFP2-15 min: 9.8±10.4%↑) were found. Exhalation of bloodborne volatile metabolites, e.g. aldehydes, hemiterpene, organosulfur, short-chain fatty acids, alcohols, ketone, aromatics, nitrile and monoterpene mirrored behaviour of cardiac output, MAP, SpO2, respiratory rate and PETCO2. Exhaled humidity (e.g. ≥60_FFP2-15 min: 7.1±5.8%↑) and exhaled oxygen (e.g. ≥60_FFP2-15 min: 6.1±10.0%↓) changed significantly (p≤0.005) over time.ConclusionsBreathomics allows unique physiometabolic insights into immediate and transient effects of face mask wearing. Physiological parameters and breath profiles of endogenous and/or exogenous volatile metabolites indicated putative cross-talk between transient hypoxaemia, oxidative stress, hypercarbia, vasoconstriction, altered systemic microbial activity, energy homeostasis, compartmental storage and washout. FFP2 masks had a more pronounced effect than surgical masks. Older adults were more vulnerable to FFP2 mask-induced hypercarbia, arterial oxygen decline, blood pressure fluctuations and concomitant physiological and metabolic effects.

Synthesis and evaluation of alkyl methacrylate-norbornene anhydride copolymers with various pendants as pour point depressants for soybean biodiesel-diesel blends

Adding more biodiesel in petrochemical diesel is one of the effective methods to alleviate the global petrochemical energy shortage, but the high-proportional biodiesel-diesel blends are always limited by the poor cold flow properties. To address this issue, a series of alkyl methacrylate-norbornene anhydride copolymers (CnMC-NA, n = 12, 14, 16, 18) with different molar ratios were synthesized as pour point depressants for B30 (30 vol% biodiesel + 70 vol% diesel). Results showed that C14MC-NA (6:1) presented the best depressive effects at 0.2 wt% dosage, and the cloud point (CP), cold filter plugging point (CFPP) and pour point (PP) of B30 have reduced by 3, 9 and 10 °C, respectively. To further improve their depressive efficiency, nine kinds of alcohols were optimized and grafted modification with C14MC-NA (6:1). The effect of these alcoholysis modified copolymers on CP, CFPP and PP of B30 were systematic researched. Results indicated that long-chain alcohols modified C14MC-NA exhibited better depressive effects on B30 than that of aromatic alcohols and short-chain alcohols. Among that, C14MC-NA-C14 at 0.15 wt% dosage exhibited the best reduction on CP, CFPP and PP of B30 by 5, 12 and 15 °C, respectively. Additionally, the mechanism was discussed by polarizing optical microscopy, rheology analysis, differential scanning calorimeter and low-temperature x-ray diffractometer.

Potentiating Vγ9Vδ2 T cell proliferation and assessing their cytotoxicity towards adherent cancer cells at the single cell level.

ABSTRACTVγ9Vδ2 T cells is the dominant γδ T cell subset in human blood. They are cytotoxic and activated by phosphoantigens whose concentrations are increased in cancer cells, making the cancer cells targets for Vγ9Vδ2 T cell immunotherapy. For successful immunotherapy, it is important both to characterise Vγ9Vδ2 T cell proliferation and optimise the assessment of their cytotoxic potential, which is the aim of this study. We found that supplementation with freshly thawed human serum potentiated Vγ9Vδ2 T cell proliferation from peripheral mononuclear cells (PBMCs) stimulated with (E)-4-Hydroxy-3-methyl-but-2-enyl diphosphate (HMBPP) and consistently enabled Vγ9Vδ2 T cell proliferation from cryopreserved PBMCs. In cryopreserved PBMCs the proliferation was higher than in freshly prepared PBMCs. In a panel of short-chain prenyl alcohols, monophosphates and diphosphates, most diphosphates and also dimethylallyl monophosphate stimulated Vγ9Vδ2 T cell proliferation. We developed a method where the cytotoxicity of Vγ9Vδ2 T cells towards adherent cells is assessed at the single cell level using flow cytometry, which gives more clear-cut results than the traditional bulk release assays. Moreover, we found that HMBPP enhances the Vγ9Vδ2 T cell cytotoxicity towards colon cancer cells. In summary, we have developed an easily interpretable method to assess the cytotoxicity of Vγ9Vδ2 T cells towards adherent cells, found that Vγ9Vδ2 T cell proliferation can be potentiated by media-supplementation and how misclassification of non-responders may be avoided. Our findings will be useful in the further development of Vγ9Vδ2 T cell immunotherapy.

Enoyl-Coenzyme A Respiration via Formate Cycling in Syntrophic Bacteria.

ABSTRACTSyntrophic bacteria play a key role in the anaerobic conversion of biological matter to methane. They convert short-chain fatty acids or alcohols to H2, formate, and acetate that serve as substrates for methanogenic archaea. Many syntrophic bacteria can also grow with unsaturated fatty acids such as crotonate without a syntrophic partner, and the reducing equivalents derived from the oxidation of one crotonate to two acetate are regenerated by the reduction of a second crotonate. However, it has remained unresolved how the oxidative and reductive catabolic branches are interconnected and how energy may be conserved in the reductive branch. Here, we provide evidence that during axenic growth of the syntrophic model organism Syntrophus aciditrophicus with crotonate, the NAD+-dependent oxidation of 3-hydroxybutyryl-CoA to acetoacetyl-CoA is coupled to the reduction of crotonyl-CoA via formate cycling. In this process, the intracellular formate generated by a NAD+-regenerating CO2 reductase is taken up by a periplasmic, membrane-bound formate dehydrogenase that in concert with a membrane-bound electron-transferring flavoprotein (ETF):methylmenaquinone oxidoreductase, ETF, and an acyl-CoA dehydrogenase reduces intracellular enoyl-CoA to acyl-CoA. This novel type of energy metabolism, referred to as enoyl-CoA respiration, generates a proton motive force via a methylmenaquinone-dependent redox-loop. As a result, the beneficial syntrophic cooperation of fermenting bacteria and methanogenic archaea during growth with saturated fatty acids appears to turn into a competition for formate and/or H2 during growth with unsaturated fatty acids.

Fuel flexibility potential for isobaric combustion in a compression ignition engine: A computational study

This work numerically explored the potential of using various kinds of fuels for the isobaric combustion concept in a compression ignition engine. Primary reference fuels (PRFs) including PRF0, PRF20, PRF40, PRF60, PRF80, and PRF100 were employed at the same middle engine load. Different injection strategies ranging from single to four injections were studied. The results demonstrated that the tested PRFs showed significant differences when using a single injection method, due to the different fuel auto-ignition characteristics: the lower fuel reactivity led to the longer ignition delay and thus more premixed combustion heat release. Fuel flexibility was achieved by utilizing at least two injection events, under which condition various fuels shared similar engine combustion performance and emissions. Predicted in-cylinder distribution of temperature revealed that the first injection event generated initial high-temperature pockets downstream of the nozzle, which helped to ignite the upstream air–fuel mixture from the following injection events and resulted in a relatively stable spray-controlled heat release process. To reduce soot emissions, various amounts of three shorter-chain alcohols (methanol, ethanol, and n-butanol) were blended with the baseline fuel (n-heptane). The methanol-blended fuels yielded the lowest soot emissions, but the fuel economy suffered due to the highest heat transfer losses. By increasing the nozzle number and introducing an adequate amount of isochoric combustion, the fuel economy for pure methanol combustion was effectively improved.