Linear Hydrocarbons Research Articles

Volatile organic compound profiling to explore primary graft dysfunction after lung transplantation

Primary graft dysfunction (PGD) is a major determinant of morbidity and mortality following lung transplantation. Delineating basic mechanisms and molecular signatures of PGD remain a fundamental challenge. This pilot study examines if the pulmonary volatile organic compound (VOC) spectrum relate to PGD and postoperative outcomes. The VOC profiles of 58 bronchoalveolar lavage fluid (BALF) and blind bronchial aspirate samples from 35 transplant patients were extracted using solid-phase-microextraction and analyzed with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. The support vector machine algorithm was used to identify VOCs that could differentiate patients with severe from lower grade PGD. Using 20 statistically significant VOCs from the sample headspace collected immediately after transplantation (< 6 h), severe PGD was differentiable from low PGD with an AUROC of 0.90 and an accuracy of 0.83 on test set samples. The model was somewhat effective for later time points with an AUROC of 0.80. Three major chemical classes in the model were dominated by alkylated hydrocarbons, linear hydrocarbons, and aldehydes in severe PGD samples. These VOCs may have important clinical and mechanistic implications, therefore large-scale study and potential translation to breath analysis is recommended.

Tuning the (Chir)Optical Properties and Squeezing out the Inherent Chirality in Polyphenylene-Locked Helical Carbon Nanorings.

Distorting linear polyaromatic hydrocarbons (PAHs) out of planarity affects their physical properties and breaks their symmetry to induce inherent chirality. However, the chirality cannot be achieved in large distorted PAHs-based macrocycles due to a low racemization barrier for isomerization. Herein, we report the precise synthesis and tuning size-dependent (chir)optical properties of a new class of chiral PAHs-containing conjugated macrocycles (cyclo[n]paraphenylene-2,6-anthrylene, [n]CPPAn2,6 ; n=6-8). Their inherent chiralities were squeezed out in small anthrylene-based macrocycles. Efficient resolutions for chiral enantiomers with (P)/(M)-helicity of small [6-7]CPPAns were achieved by HPLC. Interestingly, these macrocycles showed enriched size-dependent physical, chiral, and (chir)optical properties. Theoretical calculations indicate that these macrocycles have high strain energy (Estrain =60.8 to 73.4 kcal/mol) and very small Egap (∼3.0 eV). Notably, these enantiomers showed strong chiroptical properties and dissymmetry factors (|gabs | and |glum |∼0.01 for an enantiomer of [6]CPPAn2,6 ), which can give them potential applications in optically active materials.

Simultaneous interaction of graphene nanoflakes with cations and anions: A cooperativity study

We have investigated the structure and the stability of ternary complexes, made up of an extended aromatic π-surface that simultaneously interacts with cation and anion on the opposite faces of the aromatic π-cloud. To understand the influence of the role of aromatic surfaces in the ternary complexes, we have considered various linear and circular polycyclic aromatic hydrocarbons (PAHs) as model systems for the extended π-electron surface. The interplay between the structure, stability, and cooperativity is studied using density functional theory (DFT) methods. Furthermore, the nature of the interaction, energetics, and origin of cooperative effects in the ternary complexes are characterized by using atoms in molecules (AIM), nucleus independent chemical shift (NICS), and energy decomposition analyses (EDA). Results obtained from these calculations unravel the cooperative effects present in the ternary complexes and the interplay between cation···π and anion···π interactions when they coexist in the same system.

Size-Dependent Order-Disorder Crossover in Hydrophobic Hydration: Comparison between Spherical Solutes and Linear Alcohols.

Theory and computer simulation studies have predicted that water molecules around hydrophobic molecules should undergo an order–disorder transition with increasing solute size around a 1 nm length scale. Some theories predict the formation of a clathrate-like ordered structure around smaller hydrophobic solutes (<1 nm) and the formation of disordered vapor–liquid interfaces around larger solutes (>1 nm) and surfaces. Experimental validation of these predictions has often been elusive and contradictory. High-resolution Raman spectroscopy has detected that water around small hydrophobic solutes shows a signature similar to that of bulk water at lower temperature (increased ordering and a stronger hydrogen-bonded network). Similarly, water around larger solutes shows an increasing population of dangling OH bonds very similar to higher temperature bulk water. Thus, the solute size dependence of the structure and dynamics of water around hydrophobic molecules seems to have an analogy with the temperature dependence in bulk water. In this work, using atomistic classical molecular dynamics (MD) simulations, we have systematically investigated this aspect and characterized this interesting analogy. Structural order parameters including the tetrahedral order parameter (Q), hydrogen bond distribution, and vibrational power spectrum highlight this similarity. However, in contrast to the experimental observations, we do not observe any length-dependent crossover for linear hydrophobic alcohols (n-alkanols) using classical MD simulations. This is in agreement with earlier findings that linear alkane chains do not demonstrate the length-dependent order–disorder transition due to the presence of a sub-nanometer length scale along the cross section of the chain. Moreover, the collapsed state of linear hydrocarbon chains is not significantly populated for smaller chains (number of carbons below 20). In the context of our computational results, we raise several pertinent questions related to the sensitivity of various structural and dynamical parameters toward capturing these complex phenomena of hydrophobic hydration.

ИССЛЕДОВАНИЕ ВЯЗКОСТИ БРОМСОДЕРЖАЩЕГО ПЛАСТИФИКАТОРА ИЗ ОТХОДОВ ПРОИЗВОДСТВА

The importance of studying the viscosity parameters of liquid ingredients of plastics and elastomers for solving a number of technological issues related to taking into account the energy costs required to perform basic and auxiliary production operations in the processing of polymer materials is noted. The influence of the degree of halogenation of unsaturated mixed plasticizer obtained from industrial waste on its viscosity in the temperature range corresponding to the technological parameters of processing polymer materials 273-393 K. It is shown, that with an increase in the degree of bromination at a constant temperature the viscosity of the bromine-containing plasticizer increases by 63.3%, 52.0% and 46.8%, respectively. With an increase in temperature to 353-393 K, a decrease in the maximum viscosity values for samples with a mass fraction of bromine of 14.4% by 26% was found. It is shown that in the studied range of the degree of bromination, the viscosity drop with an increase in temperature to 393 K is 96%. An equation is proposed to evaluate the effect of the degree of bromination and temperature on the viscosity of a mixed bromine-containing plasticizer of the phthalate type, obtained from production waste. The values of its coefficients in a given temperature range are established, which characterize the change in the intensity of intermolecular interaction with an increase in the bromine content in the plasticizer. It is shown that the activation energy of the viscous flow decreases by 12% with an increase in temperature and an increase in bromine content. The heat of evaporation of the plasticizer components within 100 kJ/mol was determined. The value of a complex indicator is obtained, taking into account the combined effect of bromine content and temperature on viscosity in the range of 25-26 kJ/mol, which confirms the provisions of the activation theory for linear low-molecular hydrocarbons. It was found that the degree of influence of the bromine content in the plasticizer on its viscosity in the established temperature range is 3.3 – 4.1%. It is shown that an increase in the degree of bromination of a phthalate-type plasticizer contributes to an additional intermolecular interaction that contributes to an increase in kinematic viscosity.

Computer generation of detailed reaction networks in hydrocracking of Fischer-Tropsch wax

Fischer-Tropsch synthesis (FTS) wax is a mixture of linear hydrocarbons with carbon number from C7 to C70+. Converting FTS wax into high-quality diesel (no sulfur and nitrogen contents) by hydrocracking technology is attractive in economy and practicability. Kinetic study of the hydrocracking of FTS wax in elementary step level is very challenging because of the huge amounts of reactions and species involved. Generation of reaction networks for hydrocracking of FTS wax in which the chain length goes up to C70 is described on the basis of Boolean adjacency matrixes. Each of the species (including paraffins, olefins and carbenium ions) involved in the elementary steps is represented digitally by using a ( N + 3) × N matrix, in which a group of standardized numbering rules are designed to guarantee the unique identity of the species. Subsequently, the elementary steps are expressed by computer-aided matrix transformations in terms of proposed reaction rules. Dynamic memory allocation is used in species storage and a characteristic vector with nine elements is designed to store the key information of a ( N + 3) × N matrix, which obviously reduces computer memory consumption and improves computing efficiency. The detailed reaction networks of FTS wax hydrocracking can be generated smoothly and accurately by the current method. The work is the basis of advanced elementary-step-level kinetic modeling.

Influence Mechanism of Magnetized Modified Kerosene on Flotation Behavior of Molybdenite

The effects and mechanism of magnetized kerosene on the flotation behaviors of molybdenite were studied by micro-flotation, ultraviolet spectrum, infrared spectrum, surface tension, and liquid viscosity. According to the results of micro-flotation, magnetized kerosene improved the flotation recovery of molybdenite, and the improvements were more obvious with smaller molybdenite particles. Spectral analysis showed that the magnetization did not change the chemical composition of kerosene, but transformed the linear aliphatic hydrocarbons in kerosene into linear isomers and reduced the lengths of the carbon chains. Moreover, the magnetization reduced the viscosity of kerosene and oil/water interfacial tension, and improved the dispersion of kerosene in the pulp. The external magnetic field transformed the disorder of the additional magnetic moment in the kerosene molecules into order, and reduced the compactness of the kerosene molecules. The experimental results provided a theoretical explanation for the role of magnetization in mineral flotation.

Radicals force stubborn C bond

Making molecules with quaternary carbon bonds—four carbons attached to a central C—is tricky but necessary for medicinal chemists. Quaternary C bonds have a discrete shape and fit “lock and key” into binding sites, Princeton University chemist David MacMillan says. But quaternary Cs are hard to synthesize because they’re so bulky. MacMillan and coworkers at Princeton and pharmaceutical firm Janssen-Cilag have figured out a fix using a radical reaction that scientists speculated wasn’t possible. In what’s called an S H 2 mechanism, the group used blue light and two catalysts to trigger the addition of a three-carbon radical to the end of a linear hydrocarbon ( Science 2021, DOI: 10.1126/science.abl4322 ). The reaction is highly selective and results in a new quaternary C bond. An S N 2 reaction, common in organic chemistry, is when one reactant attacks another, resulting in a new C bond. An S H 2 reaction is

Artificial Neural Network Modeling of Glass Transition Temperatures for Some Homopolymers with Saturated Carbon Chain Backbone.

The glass transition temperature (Tg) is an important decision parameter when synthesizing polymeric compounds or when selecting their applicability domain. In this work, the glass transition temperature of more than 100 homopolymers with saturated backbones was predicted using a neuro-evolutive technique combining Artificial Neural Networks with a modified Bacterial Foraging Optimization Algorithm. In most cases, the selected polymers have a vinyl-type backbone substituted with various groups. A few samples with an oxygen atom in a linear non-vinyl hydrocarbon main chain were also considered. Eight structural, thermophysical, and entanglement properties estimated by the quantitative structure–property relationship (QSPR) method, along with other molecular descriptors reflecting polymer composition, were considered as input data for Artificial Neural Networks. The Tg’s neural model has a 7.30% average absolute error for the training data and 12.89% for the testing one. From the sensitivity analysis, it was found that cohesive energy, from all independent parameters, has the highest influence on the modeled output.

The Synthesis of Renewable Hydrocarbons from Different Vegetable Oils and Soapstock by Hydrotreatment over High Metal Loading Supported Ni Catalyst

The catalytic hydrotreatment of sunflower (SO), linseed (LO), coconut (CO), rapeseed (RO), and its soapstock derived acid oil (RS) over commercial Ni65%/SiO2-Al2O3 catalyst was investigated to evaluate utilization feasibility of various vegetable oil feedstocks with different fatty acid content, composition, and saturation for marketable hydrocarbon production. The active metal loading of catalyst was characterized by XRF and its textural properties by N2 sorption analysis. The hydrotreatment tests of different vegetable oils were carried out in solvent free medium, under initial H2 pressure 10 MPa, at operating temperature 340 oC, and residence time 15 min using catalyst amount 5%. GC-FID and GC-MS analysis were used for estimation of dominant n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, and other hydrocarbon contents in obtained samples. Under studied hydrotreatment conditions complete conversion of different vegetable oils into marketable liquid renewable hydrocarbons without presence of oxygen containing substances was achieved. Highly active Ni65%/SiO2-Al2O3 has remarkable selectivity to hydrocarbons produced by reaction pathways, where elimination of carbonyl groups occurs. The saturation of fatty acids in feedstock determines H2 consumption, but influence on produced hydrocarbon production is insignificant. Depending on the fatty acid composition different saturated linear hydrocarbons with wide range of carbon chain length C5-C19 and similar calorific value 47.16-47.34 MJ/kg were produced in process. Overall liquid hydrocarbon yields were from 44.6 % to 78.1 %. The highest overall liquid saturated linear hydrocarbon yield was observed for feedstock with high amount of long chain fatty acids – SO, LO, RO and RS. Pure hydrocarbons obtained from vegetable oils depending on hydrocarbon composition can be used in various areas.

Pyrolysis of common plastics and their mixtures to produce valuable petroleum-like products

In the present study, polystyrene (PS), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), and their mixture undergo intermediate isothermal pyrolysis at 450 °C, 500 °C, 550 °C, and 600 °C inside a tubular semi-continuous reactor under an inert nitrogen atmosphere. The liquid pyrolytic oil samples recovered in each case were analyzed through gas chromatography-mass spectrometry (GC–MS) and flame ionization detector (GC-FID) to identify and quantify the different products formed. It was found that polyethylenes (HDPE and LDPE) behave similarly in these pyrolysis conditions. For instance, GC analysis showed consecutive triplet series of linear aliphatic hydrocarbons at each carbon number of the alkane, 1-alkene, 1,(N-1)-alkadiene where N is the carbon number. On the other hand, PP, LDPE, and HDPE pyrolytic oil were rich in olefinic compounds. However, the case was quite different for PS. The pyrolytic oil was constituted totally of aromatic compounds ranging from mono to tri aromatic hydrocarbons. Styrene was the main product, along with other products such as styrene dimer, styrene trimer, benzene, toluene, bibenzyl, and α-methylstyrene. Results showed an increase in lighter hydrocarbons as the temperature increased, especially for styrene, where the weight fraction in the oil increased from 40 wt.% to 60 wt.%. Ultimately, a synergistic effect was observed with mixed plastic pyrolysis, yielding lighter compounds with a lower liquid quantity. In addition, the quality of the oil seems to be improved by the increase of around 10 wt.% of both aromatic and light compounds from the expected value at the expense of the heavier fraction. The computed lower heating value (LHV) for gaseous and liquid products ranged between 40 MJ/kg and 51 MJ/kg. A quick glance at the possible end use of each oil was investigated along with a principal component analysis (PCA) on the pyrolytic oil.

Renewable Hydrocarbon Production via Rapeseed Oil Hydrotreatment Over Palladium Catalysts

The effect of SiO2-Al2O3 (Pd5%/SA), activated carbon (Pd5%/C) and Al2O3 (Pd5%/A) supported palladium (5%) catalysts on renewable hydrocarbon synthesis via rapeseed oil hydrotreatment was investigated. The hydrotreatment experiments were carried out in solvent free medium under initial H2 pressure 100 bar and at 340 °C temperature for 120 min using catalyst amount 5%. Gas chromatography-mass spectrometry (GC/MS) analysis were used for estimation of hydrocarbon content in the obtained samples. Pd5%/SA catalyst provided complete conversion of rapeseed oil into marketable liquid renewable hydrocarbons without presence of oxygen containing substances under studied hydrotreatment conditions. Moreover, all tested Pd catalysts gave narrow range of linear saturated hydrocarbons (n-C15-C19). Pd5%/C and Pd5%/A catalysts gave partial feedstock conversion into hydrocarbons even in long residence time. Overall liquid hydrocarbon yields were from 55.3% to 82.3%.

Кровозамінники з газотранспортною функцією: надії і реалії

Робота присвячена сучасному стану проблеми створення та клінічного використання кровозамінників із газотранспортною функцією. Описано технологічні напрямки розробок кровозамінників із газотранспортною функцією. Здійснено аналіз проведених досліджень кровозамінників на основі модифікованого гемоглобіну, перфторвуглеців, а також використання молекулярних, клітинних і нанотехнологій. Надано досвід широкого клінічного застосування кровозамінника з газотранспортною функцією на основі перфторвуглеців. Продемонстровані потенційні переваги використання кровозамінників із газотранспортною функцією порівняно з алогенною кров’ю.

Conformationally Controlled Linear and Helical Hydrocarbons Bearing Extended Side Chains.

Conformationally controlled flexible molecules are ideal for applications in medicine and materials, where shape matters but an ability to adapt to multiple and changing environments is often required. The conformation of flexible hydrocarbon chains bearing contiguous methyl substituents is controlled through the avoidance of syn-pentane interactions: alternating syn-anti isomers adopt a linear conformation while all-syn isomers adopt a helical conformation. From a simple diamond lattice analysis, larger substituents, which would be required for most potential applications, result in significant and unavoidable syn-pentane interactions, suggesting substantially reduced conformational control. Through a combination of computation, synthesis, and NMR analysis, we have identified a selection of substitution patterns that allow large groups to be incorporated on conformationally controlled linear and helical hydrocarbon chains. Surprisingly, when the methyl substituents of alternating syn-anti hydrocarbons are replaced with acetoxyethyl groups, the main chain of almost 95% of the population of molecules adopt a linear conformation. Here, the side chains adopt nonideal eclipsed conformations with the main chain, thus minimizing syn-pentane interactions. In the case of all-syn hydrocarbons, concurrent removal of some methyl groups on the main chain adjacent to the large substituents is required to maintain a high population of molecules adopting a helical conformation. This information can now be used to design flexible hydrocarbon chains displaying functional groups in a defined relative orientation for multivalent binding or cooperative reactivity, for example, in targeting the interfaces defined by disease-relevant protein-protein interactions.

Linear Hydrocarbon Chain Growth from a Molecular Diruthenium Carbide Platform.

The formation of linear hydrocarbon chains by sequential coupling of C1 units on the metal surface is the central part of the Fischer-Tropsch (F-T) synthesis. Organometallic complexes have provided numerous models of relevant individual C-C coupling events but have failed to reproduce the complete chain lengthening sequence that transforms a linear Cn hydrocarbon chain into its Cn+1 homologue in an iterative fashion. In this work, we demonstrate stepwise growth of linear Cn hydrocarbon chains and their conversion to their Cn+1 homologues via consecutive addition of CH2 units on a molecular diruthenium carbide platform. The chain growth sequence is initiated by the formation of a μ-η1:η1-C═CH2 ligand from a C + CH2 coupling between the μ-carbido complex [(Cp*Ru)2(η-NPh)(μ-C)] (1; Cp* = η5-C5Me5) and Ph2SCH2. Then, the chain propagates via a general C═CHR + CH2 coupling and subsequent hydrogen-assisted isomerization of the resulting allene ligand μ-η1:η3-H2C═C═CHR to a higher vinylidene homologue μ-η1:η1-C═CH(CH2)R. By repeating this reaction sequence, up to C6 chains have been synthesized in a stepwise fashion. The key step of this chain homologation sequence is the selective hydrogenation of the μ-η1:η3-allene unit to the corresponding μ-alkylidene ligand. Isotope labeling and computational studies indicate that this transformation proceeds via the hydrogenation of the allene ligand to a terminal alkene form and its isomerization to the μ-alkylidene ligand facilitated by the coordinatively unsaturated diruthenium platform.

Pore-mouth catalysis boosting the formation of iso-paraffins from syngas over bifunctional catalysts

Recent studies confirm that the emerging bifunctional catalysts consisting of metal oxide and zeolites can directly convert syngas into high-quality gasoline, however, the formation mechanism of iso-paraffins and the difference with the conventional FT/zeolite catalyst have not been investigated. Herein, three one-dimensional SAPO zeolites with diverse micropore sizes were synthesized and assembled with ZnAlOx with spinel structure. It was found that ZnAlOx/SAPO-41 and ZnAlOx/SAPO-11 with medium micropore sizes favored the formation of C5–C11 hydrocarbons with a high content of iso-paraffins. The characterizations pointed out that the formation of iso-paraffins over SAPO-11 followed a pore-mouth catalysis mechanism, which means the isomerization of linear hydrocarbons can only take place near the pore mouth region of zeolites. This mechanism only allows the formation of mono-branched iso-paraffins in the C5–C11 range, which are less prone to be cracked than their di-branched isomers. A careful comparative analysis between ZnAlOx/SAPO-11 and Co/H-meso-ZSM-5 was also made in terms of product distribution, activity, and stability.

Chemical Fingerprinting of Polymers Using Electron Energy-Loss Spectroscopy.

Electron energy-loss spectroscopy (EELS) is becoming an important tool in the characterization of polymeric materials. The sensitivity of EELS to changes in the chemical structure of polymeric materials dictates its applicability. In particular, it is important for compositional analysis to have reference spectra of pure components. Here, we report the spectra of the carbon K-edge of six polymers (polyethylene, polypropylene, polybutylene terephthalate, and polylactic acid) including copolymers (styrene acrylonitrile and acrylonitrile butadiene styrene), to be used as reference spectra for future EELS studies of polymers. We have successfully decomposed the carbon K-edge of each of the polymers and assigned the observed peaks to bonding transitions. The spectra have been acquired in standard experimental conditions, and electron beam damage has been taken into account during establishment of spectral–structural relationships. We found that the more commonly available low-energy resolution spectrometers are adequate to chemically fingerprint linear saturated hydrocarbons such as PE, PP, and PLA. We have thus moved a step closer toward creating an atlas of polymer EELS spectra, which can be subsequently used for chemical bond mapping of polymeric materials with nanoscale spatial resolution.

Comparison of Nutritional and Nutraceutical Properties of Burdock Roots Cultivated in Fengxian and Peixian of China.

This study aimed to analyze and compare the nutritional quality of powders of burdock root from Fengxian (FX) and Peixian (PX) in China. The nutrient composition including carbohydrates, protein, amino acids, vitamin C, carotenoids, as well as total phenols, total flavonoids and phenolic compounds were investigated in addition to in vitro antioxidant capacity. The results showed that the basic nutrients of burdock root powder (BRP) in both locations did not have significant differences (p > 0.05), although the in vitro antioxidant capacity of BRP of Fengxian (F-BRP) was greater than that of PX (p < 0.05). The burdock root peel powder (BRPP) possessed more phenolics and stronger in vitro antioxidant capacity than the burdock root powder (BRP) and peeled burdock root powder (PBRP) (p < 0.05). Moreover, better quality burdock root was obtained from FX. F-BRP was consequently analyzed by ultra-performance liquid chromatography tandem mass spectrometry for its phenolic composition. Seventeen phenolics, mainly caffeoylquinic acids, were detected. In addition, a total of 181 volatile compounds belonging to eight types were detected including alcohols, aldehydes, ketones, alkenes, esters, acids, linear or aromatic hydrocarbons, and others. The diverse compounds found in this study can provide a theoretical basis for the development and utilization of burdock in the food industry.

Inside Cover: Molecular Basis for Two Stereoselective Diels–Alderases that Produce Decalin Skeletons (Angew. Chem. Int. Ed. 41/2021)

A linear hydrocarbon chain containing a diene and a dienophile is folded and transformed into a decalin scaffold by intramolecular [4+2] cycloaddition. The substrates are folded oppositely but bind in the same orientation to the pockets of a pair of Diels–Alderases to yield enantiomeric decalin skeletons, as reported by Naoki Kato, Shunji Takahashi, Shingo Nagano, and co-workers in their Research Article on page 22401.

Appetitive olfactory learning suffers in ants when octopamine or dopamine receptors are blocked.

Associative learning relies on the detection of coincidence between a stimulus and a reward or punishment. In the insect brain, this process is carried out in the mushroom bodies under the control of octopaminergic and dopaminergic neurons. It was assumed that appetitive learning is governed by octopaminergic neurons, while dopamine is required for aversive learning. This view has recently been challenged: both neurotransmitters are involved in both types of learning in bees and flies. Here, we tested which neurotransmitters are required for appetitive learning in ants. We trained Lasius niger workers to discriminate two mixtures of linear hydrocarbons and to associate one of them with a sucrose reward. We analysed the walking paths of the ants using machine learning and found that the ants spent more time near the rewarded odour than near the other, a preference that was stable for at least 24 h. We then treated the ants before learning with either epinastine, an octopamine receptor blocker, or flupentixol, a dopamine receptor blocker. Ants with blocked octopamine receptors did not prefer the rewarded odour. Octopamine signalling is thus necessary for appetitive learning of olfactory cues, probably because it signals information about odours or reward to the mushroom body. In contrast, ants with blocked dopamine receptors initially learned the rewarded odour but failed to retrieve this memory 24 h later. Dopamine is thus probably required for long-term memory consolidation, independent of short-term memory formation. Our results show that appetitive olfactory learning depends on both octopamine and dopamine signalling in ants.