Diffusion Experiments Research Articles

Ion bombardment induced surface microstructural modification of aluminum alloy

Surface microstructural modifications of 2A12 aluminum alloy exposed to 60 keV Ar ion bombardment with the dose of 1 × 1017 ions/cm2 under vacuum were studied in detail. The amorphous layer with the thickness of ∼130 nm accompanied with polycrystalline aluminum was formed at the surface after Ar ion bombardment. Beneath the amorphous layer, Al2CuMg precipitates were observed. Dynamic recrystallization(DRX)and grain growth were observed with the increment of texture intensity. Surface residual compressive stress and strain were enhanced characterized by electron back-scattered diffraction. After ion bombardment, the contact angles of diiodomethane and DI water on aluminum alloy were increased, and a notable decrement of surface energy of aluminum alloy was measured from 32.5 mJ/m2 to 23.4 mJ/m2. The diffusion experiments indicated that the mutual diffusion of Cu and Al was inhibited due to the bombardment-induced amorphous layer at aluminum alloy surface, which is beneficial to its application as a structure material in aerospace field.

Al-26 and O-18 tracer diffusion in a titania-coated sodium aluminosilicate glass

Although TiO2 is a common nucleating agent in the production of aluminosilicate glass-ceramics, its role as a catalyst for the nucleation of the functional crystal remains unclear. Therefore, the Ti, Al and O mobility was studied in situ using 26Al and 18O tracer diffusion and Ti chemical diffusion experiments in an aluminosilicate melt of albite composition. The albite glass serves as a surrogate for lithium and magnesium aluminosilicate glass-ceramic compositions, as it allows to study atomic mobilities free of crystallisation artefacts. The depth profiles showed that Al mobility increased significantly and became comparable to that of oxygen when Ti simultaneously diffused into the glass. In the absence of Ti, the diffusivity of Al was two orders of magnitude lower than that of oxygen. The co-diffusion coefficients of Ti and Al seem to confirm a proposed preferential structural linkage between Al and Ti species in the network structure of aluminosilicate melts.

Chloride binding and diffusion of slag blended concrete mixtures

Ground granulated blast furnace slags (GGBFS/slag) can have a range of chemical compositions, especially in alumina content that could potentially affect several concrete properties including chloride binding capacity and chloride penetration. Chloride binding capacity and diffusivity of several cement-slag combinations were assessed using two slags of 8% and 17% alumina contents and four cements, ASTM C150 Type I, ASTM C150 Type I (high alkali), ASTM C150 Type II(MH) and ASTM C595 Type IL(14) at a cement replacement level of 60%. The findings indicate slag addition improved chloride binding and lowered chloride diffusivity. Between the two slags, chloride binding capacity was higher in high alumina slag. Type I cement mixtures had the highest binding capacity while it was the lowest in Type IL cement mixtures due to lower C3A, C3S and clinker factor. Chloride diffusivity experiments showed that plain Type IL mixture had the highest chloride ion penetration while it was the lowest when blended with high alumina slag due to carboaluminate formation. Therefore, chemical, mineralogical, and physical characteristics of cement-slag combination should be considered in service life analysis of slag blended concrete mixtures.

Effect of Chitosan as Active Bio-colloidal Constituent on the Diffusion of Dyes in Agarose Hydrogel.

Agarose hydrogel was enriched by chitosan as an active substance for the interactions with dyes. Direct blue 1, Sirius red F3B, and Reactive blue 49 were chosen as representative dyes for the study of the effect of their interaction with chitosan on their diffusion in hydrogel. Effective diffusion coefficients were determined and compared with the value obtained for pure agarose hydrogel. Simultaneously, sorption experiments were realized. The sorption ability of enriched hydrogel was several times higher in comparison with pure agarose hydrogel. Determined diffusion coefficients decreased with the addition of chitosan. Their values included the effects of hydrogel pore structure and interactions between chitosan and dyes. Diffusion experiments were realized at pH 3, 7, and 11. The effect of pH on the diffusivity of dyes in pure agarose hydrogel was negligible. Effective diffusion coefficients obtained for hydrogels enriched by chitosan increased gradually with increasing pH value. Electrostatic interactions between amino group of chitosan and sulfonic group of dyes resulted in the formation of zones with a sharp boundary between coloured and transparent hydrogel (mainly at lower pH values). A concentration jump was observed at a given distance from the interface between hydrogel and the donor dye solution.

Zinc Oxide Nanoparticles as The Anti-Bacterial Tool: In Vitro Study

A new class of metal oxide nanoparticles has recently been found to be widely used in various health-related research. In particular, Zinc Oxide (ZnO) nanoparticles have occupied a prominent status due to their unique chemical and electrical properties. In our study, we aim to reveal the anti-bacterial effect of these nanoparticles. The antibacterial activity of zinc oxide (ZnO) nanoparticles against isolated pathogenic Escherichia coli (strain MTCC 723) was determined from our study. The antimicrobial properties of ZnO were also determined by adjusting the concentration of ZnO nanoparticles. By sonicating ZnO nanoparticles in water, a homogenized suspension was created, and the infusion was made at 50 – 150g/ml concentrations. Anaerobic conditions were used to culture the pathogenic strain of microbial species, and DNA was extracted using an extraction kit. For testing, equalized standard dilutions of cultivated bacteria were utilized. The anti-bacterial capabilities of zinc oxide (ZnO) nanoparticles against bacteria were measured using spectroscopic and diffusion experiments. ZnO nanoparticles with a diameter of 50 nm and a concentration of 150 g/ml lysed Escherichia coli DNA and cells. According to the findings, ZnO nanoparticles with a concentration of 150 g/ml had significantly more vigorous activity against Escherichia coli. The agar diffusion method was used to quantify the anti-bacterial activity of zinc oxide (ZnO) and the quality and amount of DNA extraction in the presence of ZnO nanoparticles (ZnO). The pathogenic Escherichia coli cells and the gene DNA are killed at the optimal dose. This study aims to know the anti-bacterial properties of ZnO nanoparticles against pathogenic Escherichia coli cells. The optimization of ZnO nanoparticles concentration against its effect on Escherichia coli cells is the next aim of this study.

Effects of Phytoncide Extracts on Antibacterial Activity, Immune Responses, and Stress in Dogs

Background and objective: Phytoncides are volatile and antibacterial organic compounds emitted by plants. In humans, these compounds are known to confer anti-bacterial, antioxidative, anti-inflammatory, immune-response-enhancing, and stress-reducing benefits. However, it remains largely unknown if phytoncides have parallel effects on dogs. Therefore, the aim of this study is to determine if phytoncides exhibit antibacterial activity, initiate an immune response, or alter stress hormone dynamics in dogs.Methods: Phytoncide extracts used in the study were obtained from Hinoki cypress (<i>Chamaecyparis obtuse</i>) and Korean red pine (<i>Pinus densiflora</i>). To examine the effectiveness of the extracts at initiating and sustaining anti-microbial activity in dogs, we conducted a disc diffusion experiment on bacteria that cause skin diseases in the dog. Furthermore, we evaluated the effects of phytoncides on the immune response and stress hormone levels of dogs by spraying the phytoncide extract on the skin of the beagle twice a day for eight weeks.Results: In this study, we investigated the effectiveness of phytoncides in eliminating bacteria cause skin infections in dogs. Our results confirm that mixed phytoncide extract was more effective than either phytoncide extract alone. After eight weeks, blood was collected from the common carotid artery of the beagle; we then measured the levels of immune response factors and cortisol. We found that with regards to the composition of white blood cells (WBCs), phytoncides significantly increased the proportion of lymphocytes and mononucleotides. They also increased the levels of immunoglobulin G and interferon-γ, while decreasing cortisol levels. Effects on several other immune markers were not significant.Conclusion: We suggest that mixed phytoncide extracts have antibacterial effects in dogs. Additionally, these compounds seem to enhance immunity and reduce stress in dogs.

Lecithin as an Effective Modifier of the Transport Properties of Variously Crosslinked Hydrogels.

Transport properties are one of the most crucial assets of hydrogel samples, influencing their main application potential, i.e., as drug carriers. Depending on the type of drug or the application itself, it is very important to be able to control these transport properties in an appropriate manner. This study seeks to modify these properties by adding amphiphiles, specifically lecithin. Through its self-assembly, lecithin modifies the inner structure of the hydrogel, which affects its properties, especially the transport ones. In the proposed paper, these properties are studied mainly using various probes (organic dyes) to effectively simulate drugs in simple release diffusion experiments controlled by UV-Vis spectrophotometry. Scanning electron microscopy was used to help characterize the diffusion systems. The effects of lecithin and its concentrations, as well as the effects of variously charged model drugs, were discussed. Lecithin decreases the values of the diffusion coefficient independently of the dye used and the type of crosslinking. The ability to influence transport properties is better observed in xerogel samples. The results, complementing previously published conclusions, showed that lecithin can alter a hydrogel's structure and therefore its transport properties.

The effects of growth modifiers on the catalytic performance of hierarchical Pd/ZSM-23 bifunctional catalysts for n-hexadecane hydroisomerization

Hydroisomerization of n-alkanes catalyzed by metal-zeolite bifunctional catalysts is an important process to produce clean biofuels. The employment of appropriate growth modifiers during the synthesis of hierarchical zeolites to increase the iso-alkane yield has captured much attention. In this work, cetyltrimethylammonium bromide (CTAB) and polydiallyl dimethyl ammonium chloride (PDDA), representatives of cationic surfactants and cationic polyelectrolytes, are added to the initial gel to one-pot synthesize hierarchical ZSM-23 zeolites (Z23-xPC and Z23-yPP) via the bottom-up strategy. The corresponding Pd/ZSM-23 catalysts are prepared by loading 0.5 wt% Pd on microporous and hierarchical ZSM-23 and tested for the hydroisomerization of n-hexadecane. Due to the cationic adsorption of CTAB or steric hindrance effect of PDDA, Z23-xPC and Z23-yPP samples all demonstrate enhanced mesoporosity compared with the conventional microporous Z23-P sample. The diffusivity experiments indicates that the D/L2 values decrease in the order of Pd/Z23-5PP > Pd/Z23-3PC > Pd/Z23-P, suggesting that the hydrocarbons diffusion in the channel of hierarchical ZSM-23 samples is evidently improved. In addition, the Brønsted acid densities of the Z23-xPC and Z23-yPP samples are also evidently reduced compared to that of the microporous Z23-P sample because of the proportion decreases of framework Al atoms at T2-T5 sites. Compared with the microporous Pd/Z23-P catalyst, the appropriate addition amount of growth modifiers can evidently improve the yield of iso-hexadecane products and limit the cracking process. Especially for the Pd/Z23-5PP catalyst, the cracking process is effectively limited and the maximum iso-hexadecane yield of 75.4% is obtained at an n-hexadecane conversion of 88.8% at 290 °C, which is the highest among all catalysts. Therefore, this work has provided an effective method for the simple preparation of bifunctional catalysts with improved diffusion performance and more favorable metal–acid balance.

Measuring dissolved He diffusion coefficients and 3He and 4He fractionation during diffusion through sandstone

The He concentration in groundwater has been used as a tracer for groundwater age in numerous studies and this requires an understanding of He provenance and accumulation in the target aquifer. Few studies of dissolved He diffusion through rocks have been performed even though He diffusion into or out of adjacent aquitards can strongly affect the He concentration in groundwater. Additionally, little information about 3He and 4He fractionation during diffusion is available. Information about 3He fractionation may improve our understanding of the migration history (diffusion and/or advection) of He in groundwater, but this will require our understanding of 3He and 4He fractionation during diffusion processes to be improved. A new system for performing diffusion experiments was developed in this study. Dissolved He in a downstream cell was separated from the bulk solution using a silicon tube coil and measurements were made using a sample loop directly connected to a gas chromatograph. The system minimizes He degassing and contamination by air because sampling and analysis are performed while keeping the system closed. Dissolved He diffusion coefficients (DHe) for three types of sandstone (Tako, Kimachi, and Izumi sandstone) were determined, and the values were 18 × 10−11, 10 × 10−11, and 1.6 × 10−11 m2/s, respectively. Cl− diffusion coefficients (DCl) and D2O diffusion coefficients (DD2O) were also determined and compared with the DHe values. Formation factors were calculated from the coefficients for diffusion through the rocks and in free water. The He and D2O formation factors agreed well for all three sandstones, indicating that dissolved He and water diffused through similar rock pore paths. The Cl− formation factors were lower than the He and D2O formation factors, possibly because of anion exclusion. It was inferred that DHe for sandstone can be roughly predicted from DD2O. 3He and 4He fractionation was assessed by comparing the 3He/4He ratios before and after diffusion through rock pores. The D3He to D4He ratios for Tako, Kimachi, and Izumi sandstone were 1.137, 1.139, and 1.179, respectively. The Tako and Kimachi sandstone D3He/D4He ratios were similar to the D3He/D4He ratio for free water. The D3He/D4He ratio was markedly higher for Izumi sandstone than free water, indicating that collisions with pore walls may affect 3He and 4He fractionation during diffusion through some rock pores.

Bayesian calibration with summary statistics for the prediction of xenon diffusion in UO2 nuclear fuel

The evolution and release of fission gas impacts the performance of UO2 nuclear fuel. We have created a Bayesian framework to calibrate a novel model for fission gas transport that predicts diffusion rates of uranium and xenon in UO2 under both thermal equilibrium and irradiation conditions. Data sets are taken from historical diffusion, gas release, and thermodynamic experiments. These data sets consist invariably of summary statistics, including a measurement value with an associated uncertainty. Our calibration strategy uses synthetic data sets in order to estimate the parameters in the model, such that the resulting model predictions agree with the reported summary statistics. In doing so, the reported uncertainties are effectively reflected in the inferred uncertain parameters. Furthermore, to keep our approach computationally tractable, we replace the fission gas evolution model by a polynomial surrogate model with a reduced number of parameters, which are identified using global sensitivity analysis. We discuss the efficacy of our calibration strategy, and investigate how the contribution of the different data sets, taken from multiple sources in the literature, can be weighted in the likelihood function constructed as part of our Bayesian calibration setup, in order to account for the different number of data points in each set of data summaries. Our results indicate a good match between the calibrated diffusivity and non-stoichiometry predictions and the given data summaries. We demonstrate a good agreement between the calibrated xenon diffusivity and the established fit from Turnbull et al. (1982), indicating that the dominant uranium vacancy diffusion mechanism in the model is able to capture the trends in the data.

Direct dating of overprinting fluid systems in the Martabe epithermal gold deposit using highly retentive alunite

Abstract. The Martabe gold deposits in Sumatra formed in a shallow crustal epithermal environment associated with intermediate mafic intrusions adjacent to an active right-lateral wrench system. Gas/fluid temperatures reached 200–350 ∘C. The structural geology suggests episodic switches in stress orientations during a Plio-Pleistocene seismotectonic evolution. Different mineralisation events may have been associated with oscillations in this earthquake cycle, so samples containing alunite were collected for 40Ar / 39Ar geochronology to constrain the timing. 39Ar diffusion experiments were performed to constrain variation in argon retentivity. The age spectra were produced by incremental step-heating with heating times chosen so similar percentages of 39Ar gas release occurred during as many steps as possible. This ensured the detail necessary for analysis of the complex morphology of these spectra by applying the method of asymptotes and limits, which enabled recognition of different growth events of alunite in overprinting fluid systems. It was possible to provide estimates as to the frequency of individual events and their duration. The heating schedule also ensured that Arrhenius data populated the inverse temperature axis with sufficient detail to allow modelling. Activation energies were between 370–660 kJ mol−1. Application of Dodson's recursion determined closure temperatures that range from 400–560 ∘C for a cooling rate of 100 ∘C Ma−1. Such estimates are higher than any temperature to be expected in the natural system, giving confidence that the ages represent the timing of growth during periods of active fluid movement and alteration: a hypothesis confirmed by modelling age spectra using the MacArgon program. We conclude that gold in the Purnama pit resulted from overprinting fluid rock interactions during very short mineralisation episodes at ∼2.25 and ∼2.00 Ma.

A Turn-On and Colorimetric Probe Based on Isophorone Skeleton for Detecting Nerve Agent Mimic Diethyl Chlorophosphite

A new turn-on probe (SWJT-20) based on isophorone fluorophore for the detection of nerve agent mimic diethyl chlorophosphite (DCP) was designed and synthesized. SWJT-20 could rapidly respond to DCP within 2 s using UV-Vis or fluorescent spectra, accompanied by a significant change in the solution color under visible light or UV light, which could be observed by the naked eyes. The detection limit of SWJT-20 to DCP was as low as 8.3 nM, which is lower than those of most reported fluorescent probes for DCP detection. Additionally, SWJT-20 could quantitatively measure DCP using ratio changes in A427/A645 in absorption spectra. Furthermore, facile paper as sensors with the visualization of colorimetric/fluorometric responses based on SWJT-20 has been fabricated. Notably, this probe could detect DCP vapor through gas diffusion experiments.

Hyperloop-like diffusion of long-chain molecules under confinement

The ultrafast transport of adsorbates in confined spaces is a goal pursued by scientists. However, diffusion will be generally slower in nano-channels, as confined spaces inhibit motion. Here we show that the movement of long-chain molecules increase with a decrease in pore size, indicating that confined spaces promote transport. Inspired by a hyperloop running on a railway, we established a superfast pathway for molecules in zeolites with nano-channels. Rapid diffusion is achieved when the long-chain molecules keep moving linearly, as well as when they run along the center of the channel, while this phenomenon do not exist for short-chain molecules. This hyperloop-like diffusion is unique for long-chain molecules in a confined space and is further verified by diffusion experiments. These results offer special insights into molecule diffusion under confinement, providing a reference for the selection of efficient catalysts with rapid transport in the industrial field.

Transcriptomic Changes and satP Gene Function Analysis in Pasteurella multocida with Different Levels of Resistance to Enrofloxacin

Pasteurella multocida (Pm) is one of the major pathogens of bovine respiratory disease (BRD), which can develop drug resistance to many of the commonly used antibiotics. Our earlier research group found that with clinical use of enrofloxacin, Pm was more likely to develop drug resistance to enrofloxacin. In order to better understand the resistance mechanism of Pm to enrofloxacin, we isolated PmS and PmR strains with the same PFGE typing in vitro, and artificially induced PmR to obtain the highly resistant phenotype, PmHR. Then transcriptome sequencing of clinically isolated sensitive strains, resistant and highly drug-resistant strains, treated with enrofloxacin at sub-inhibitory concentrations, were performed. The satP gene, of which the expression changed significantly with the increase in drug resistance, was screened. In order to further confirm the function of this gene, we constructed a satP deletion (ΔPm) strain using suicide vector plasmid pRE112, and constructed the C-Pm strain using pBBR1-MCS, and further analyzed the function of the satP gene. Through a continuously induced resistance test, it was found that the resistance rate of ΔPm was obviously lower than that of Pm in vitro. MDK99, agar diffusion and mutation frequency experiments showed significantly lower tolerance of ΔPm than the wild-type strains. The pathogenicity of ΔPm and Pm was measured by an acute pathogenicity test in mice, and it was found that the pathogenicity of ΔPm was reduced by about 400 times. Therefore, this study found that the satP gene was related to the tolerance and pathogenicity of Pm, and may be used as a target of enrofloxacin synergistic effect.

Mechanomemory in protein diffusivity of chromatin and nucleoplasm after force cessation

It is known that external mechanical forces can regulate structures and functions of living cells and tissues in physiology and diseases. However, after cessation of the force, how structures are altered in response to the dynamics of the chromatin and molecules in the nucleoplasm remains elusive. Here, using single-molecule imaging approaches, we show that exogenous local forces via integrins applied for 2 to 10 min decondensed the chromatin and increased chromatin and nucleoplasm protein mobility inside the nucleus, leading to elevated diffusivity of single protein molecules in the nucleoplasm, tens of minutes after the cessation of force. Diffusion experiments with fluorescence correlation spectroscopy in live single cells show that the mechanomemory in chromatin and nucleoplasm protein diffusivity was regulated by nuclear pore complexes. Protein molecular dynamics simulation recapitulated the experimental findings in live cells and showed that nucleoplasm protein diffusivity was regulated by the number of nuclear pore complexes. The mechanomemory in elevated protein diffusivity of the nucleoplasm after force cessation represents a physical process that reverses protein-protein condensation in phase separation via unjamming of the chromatin. Our findings of mechanomemory in chromatin and nucleoplasm protein diffusivity suggest that the effect of force on the nucleus remains tens of minutes after force cessation and thus is more far-reaching than previously anticipated.

Bumblebees acquire alternative puzzle-box solutions via social learning.

The astonishing behavioural repertoires of social insects have been thought largely innate, but these insects have repeatedly demonstrated remarkable capacities for both individual and social learning. Using the bumblebee Bombus terrestris as a model, we developed a two-option puzzle box task and used open diffusion paradigms to observe the transmission of novel, nonnatural foraging behaviours through populations. Box-opening behaviour spread through colonies seeded with a demonstrator trained to perform 1 of the 2 possible behavioural variants, and the observers acquired the demonstrated variant. This preference persisted among observers even when the alternative technique was discovered. In control diffusion experiments that lacked a demonstrator, some bees spontaneously opened the puzzle boxes but were significantly less proficient than those that learned in the presence of a demonstrator. This suggested that social learning was crucial to proper acquisition of box opening. Additional open diffusion experiments where 2 behavioural variants were initially present in similar proportions ended with a single variant becoming dominant, due to stochastic processes. We discuss whether these results, which replicate those found in primates and birds, might indicate a capacity for culture in bumblebees.

Influence of pseudoboehmite on the performance of shaped mordenite catalyst for dimethyl ether carbonylation

As a key step of indirect production of ethanol from syngas, the carbonylation of dimethyl ether (DME) has attracted much attention. It is of great importance to develop shaped catalyst with high efficiency and strong mechanical properties to promote the process industrialization. Extruded mordenite (MOR) has been used as the catalyst for industrial DME carbonylation. In this work, the effect of properties and content of pseudoboehmite as a binder on mechanical strength and catalytic performance of the extruded MOR were systematically studied. Combining TG, XRD, N2 adsorption, and rheological property analysis etc., we found that the interlayer water content of pseudoboehmite affect peptization process, which leads to the difference in mechanical strength and pore structure. Then, the DME carbonylation performance of the extruded MOR was discussed based on textural parameters and acidic properties. Further, DME diffusion experiments were conducted and analyzed by using standard and the time-fractional diffusion models respectively. As a result, the influence of pseudoboehmite on mass transfer performance was quantitatively analyzed. The results will provide important guidance for the development of shaped zeolite catalysts in industry.

Locating the source of self-potential using few-shot learning

Self-potential method has the advantages of convenience, rapidity and sensitivity. It has many applications in geophysical exploration. Therefore, the inversion problem of self-potential is very important. In order to obtain the location of the source, we propose a new self-potential inversion method based on few-shot learning. Firstly, a fully-connected neural network is used to extract the features of self-potential data and the data of well-surface pole–pole device method, and then the cosine distance is used to calculate the similarity between them. So, we can transform the positioning problem on the two-dimensional (2D) profile into the classification problem in two directions. In order to verify the feasibility of this method, we carried out a simulated landfill leakage experiment and a field saline water diffusion experiment, and both achieved good results. Compared with self-potential tomography method, the positioning accuracy of our method is increased by about 10.42%. Compared with traditional deep learning methods, we combine multimodal data to make the results more interpretable. In addition, the results of the two experiments also prove that our method has strong generalization ability, which provides a new idea to solve the differences between the simulation model and the actual field.

Experiment of N2O4 Leakage and Diffusion in A Closed Space

The paper, by experiment of physical simulation, researched the leakage and diffusion law of N2O4 in a specific closed space. To simulate N2O4 leakage, the experiment pumped a certain amount of N2O4 gas into a specific space from a simulated leak point. And some electrochemical sensors were used to detect the concentration of N2O4 gas in some places in the space. The result showed that N2O4 diffused in the space, and the sensors facing to and near to the leak point sensed N2O4 gas at first. In the beginning, N2O4 diffused faster in the places below than above, and the bigger the leakage amount, the higher the concentration. After a while, N2O4 gas got even by diffusion, and the bigger the leaked amount was, the bigger the even concentration. If the environmental temperature was high, the even concentration in the lower part was higher a bit than that in the upper part. And the specific distribution of concentration was decided by the shape of the space.

CO2 diffusion in dry and hydrous leucititic melt

Abstract. Using the diffusion couple technique, diffusion of CO2 in a leucititic melt from the Colli Albani Volcanic District in Italy was investigated at temperatures between 1200 and 1350 ∘C in an internally heated pressure vessel at 300 MPa. To examine the effect of dissolved H2O in the melt, experiments were performed for a nominally dry melt (0.18 ± 0.03 wt % H2O) and for a hydrous melt containing 3.36 ± 0.28 wt % H2O. Diffusion experiments were run for 40 to 120 min and terminated by rapid quench. CO2 concentration profiles were subsequently measured via attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and fitted with error functions to obtain individual diffusion coefficients. For the anhydrous and hydrous sample series, seven diffusion coefficients were determined each. Diffusivity was found to increase exponentially with temperature for both melts following an Arrhenius behaviour. The Arrhenius equation for the nominally dry leucititic melt is described by log⁡DCO2=-1.44(±0.24)⋅10000T-1.95(±1.59), where DCO2 is the diffusion coefficient in m2 s−1 and T is the temperature in K. In the experimental temperature range, H2O has an accelerating effect on CO2 diffusion. At 1200 ∘C, diffusivity increases from 1.94 × 10−12 m2 s−1 in the dry melt to 1.54 × 10−11 m2 s−1 in the hydrous melt. The Arrhenius equation for the leucititic melt containing 3.36±0.28 wt % H2O is given by log⁡DCO2=-1.09(±0.30)⋅10000T-3.41(±1.99). The activation energies for CO2 were determined to be 275 ± 47 kJ mol−1 for the anhydrous melt and 209 ± 58 kJ mol−1 for the hydrous melt. The high CO2 activation energy in the leucititic melt indicates that the diffusion might be partly attributed to the carbonate species. At high magmatic temperatures above 1200 ∘C, CO2 diffusivity in the leucititic melt is only slightly lower than CO2 diffusion in rhyolitic and basaltic melts, suggesting that CO2 diffusion in natural melts is relatively independent from the bulk melt composition at such temperatures. CO2 diffuses slower than other volatile components such as halogens and H2O in depolymerized silicate melts. Thus, a fractionation of volatiles can occur during magma ascent and degassing. The experimental data on CO2 diffusion can be used for modelling the degassing mechanisms of ultrapotassic mafic melts.