Temperature-induced Increase Research Articles

Thermal transport in C6N7 monolayer: a machine learning based molecular dynamics study

The successful synthesis of a novel C6N7carbon nitride monolayer offers expansive prospects for applications in the fields of semiconductors, sensors, and gas separation technologies, in which the thermal transport properties of C6N7are crucial for optimizing the functionality and reliability of these applications. In this work, based on our developed machine learning potential (MLP), molecular dynamics (MD) simulations including homogeneous non-equilibrium, non-equilibrium, and their respective spectral decomposition methods are performed to investigate the effects of phonon transport, temperature, and length on the thermal conductivity of C6N7monolayer. Our results reveal that low-frequency and in-plane phonon modes dominate the thermal conductivity. Notably, thermal conductivity decreases with an increase in temperature due to temperature-induced increase in phonon-phonon scattering of in-plane phonon modes, while it increases with an extension in sample length. Our findings based on MD simulations with MLP contribute new insights into the lattice thermal conductivity of holey carbon nitride compounds, which is helpful for the development of next-generation electronic and photonic devices.

Multiple-model based simulation of urban atmospheric methane concentration and the attributions to its seasonal variations: A case study in Hangzhou megacity, China

Cities are treated as global methane (CH4) emission hotspots and the monitoring of atmospheric CH4 concentration in cities is necessary to evaluate anthropogenic CH4 emissions. However, the continuous and in-situ observation sites within cities are still sparsely distributed in the largest CH4 emitter as of China, and although obvious seasonal variations of atmospheric CH4 concentrations have been observed in cities worldwide, questions regarding the drivers for their temporal variations still have not been well addressed. Therefore, to quantify the contributions to seasonal variations of atmospheric CH4 concentrations, year-round CH4 concentration observations from 1st December 2020 to 30th November 2021 were conducted in Hangzhou megacity, China, and three models were chosen to simulate urban atmospheric CH4 concentration and partition its drivers including machine learning based Random Forest (RF) model, atmospheric transport processes based numerical model (WRF-STILT), and regression analysis based Multiple Linear Regression (MLR) model. The findings are as follows: (1) the atmospheric CH4 concentration showed obvious seasonal variations and were different with previous observations in other cities, the seasonality were 5.8 ppb, 21.1 ppb, and 50.1 ppb between spring-winter, summer-winter and autumn-winter, respectively, where the CH4 background contributed by −8.1 ppb, −44.6 ppb, and −1.0 ppb, respectively, and the CH4 enhancements contributed by 13.9 ppb, 65.7 ppb, and 51.1 ppb. (2) The RF model showed the highest accuracy in simulating CH4 concentrations, followed by MLR model and WRF-STILT model. (3) We further partition contributions from different factors, results showed the largest contribution was from temperature-induced increase in microbial process based CH4 emissions including waste treatment and wetland, which ranged from 38.1 to 76.3 ppb when comparing different seasons with winter. The second largest contribution was from seasonal boundary layer height (BLH) variations, which ranged from −13.4 to −6.3 ppb. And the temperature induced seasonal CH4 emission and enhancement variations were overwhelming BLH changes and other meteorological parameters.

Neurotransmitter metabolites in milk ferments of Leuconostoc mesenteroides regulate temperature-sensitive heartbeats in an ex ovo model

Accumulated evidence has supported the probiotic activity of Leuconostoc mesenteroides (L. mesenteroides) which can yield beneficial metabolites via fermentation. Here, bovine milk rich in phenylalanine（PHE) was used as a source for fermentation of L. mesenteroides. The complexes of PHE with bacterial phenylalanine hydroxylase (PheH) at two temperatures were revealed via molecular dynamics simulation. Two carbon hydrogen bonds and a Pi-Alkyl T-shaped interaction were newly formed at an active site of the PheH-PHE complex. The PheH interacted with two different hydrogen atoms in an amine of PHE via conventional hydrogen bonds at 37 °C, a temperature that accelerated the milk fermentation of L. mesenteroides. Twenty-eight metabolites including various neurotransmitters in fermented milk were identified and quantified by liquid chromatography coupled to quadrupole ion trap (Q-Trap) tandem mass spectrometry. Ex ovo injection of milk ferments into the yolk sac of chicken embryos enhanced a rising temperature-induced increase in heartbeats towards the normal resting level. The neurotransmitter-rich milk ferments hold potential for using to adjust energy metabolism, referred from heart rates, during fluctuating temperature conditions.

Interfacial negative magnetization in Ni encapsulated layer-tunable nested MoS2 nanostructure with robust memory applications.

Combining interfacial interactions and layer-number tunability, the evolution of magnetism in low-dimensional diamagnetic systems like MoS2 is indeed an interesting area of research. To explore this, Ni nanophases with an average size of 12 nm were encapsulated in MoS2 and the magnetization dynamics were studied over the temperature range of 2-300 K. Surprisingly, the newly formed hybrid nanostructure was found to have a negative magnetization state with giant exchange bias that showed a reversible temperature-induced increase in both spin magnetic moment and coercivity. Density functional theory calculations proved an interfacial charge transfer interaction with a spin-polarized density of states. The magnetization state, along with giant exchange correlation among the magnetic clusters, suggested the possibility of robust thermomagnetic memory. The dc magnetization and relaxation, investigated with different measurement protocols, unveiled robust thermoremanent magnetization as a memory effect. The time-dependent magnetization study indicated that contributions from the negative magnetization state along with charge transfer induced spin states are responsible for the memory effect, which can be controlled by both temperature and external field.

Dynamic tensile fracture of iron: Molecular dynamics simulations and micromechanical model based on dislocation plasticity

Molecular dynamics (MD) shows a difference in the mechanisms of fracture of iron under uniaxial and isotropic tension. Uniaxial tension leads to the formation of a complex dislocation structure in the bulk of material, which reduces the pore formation threshold and spall strength. Increase in temperature up to about 900 K suppresses increase in dislocation density during uniaxial tension, which leads to increase in the spall strength to the level close to the case of hydrostatic (isotropic) tension. This temperature-induced increase in dynamic tensile strength is rather unusual. Preliminary compression of material mimicking the shock compression prior to tension creates a defect structure, which reduces the spall strength during the following tension. The MD results of isotropic tension are used to model the material fracture dynamics on continuum level. The Bayesian approach to model calibration is used to identify the parameters of the fracture model. The parameterized fracture model describes well the MD results in the considered temperature range 300–1100 K. The fracture model with additional accounting of void initiation on initial defects of material is used to describe the experimental observations of the spall strength of iron over a wide range of strain rates. The simulation results for undeformed iron are in good agreement with the experimental values of the spall strength at strain rates greater than 4 × 105 s-1 and give overestimated values at lower strain rates. The results of calculations for precompressed iron describe well the spall strength over the entire range of strain rates indicating that accounting for the defect structure created by the shock compression prior to tension is critical for moderate strain rates.

Effect of temperature-induced contact quality evolution on nanoscale friction

Multiple subcontacts formation/rupture and puckering the evolution of contact quality play crucial roles in modulating friction on two-dimensional lamellar materials but have up to now been studied separately in the field of nanotribology. In this work, by using variable temperature friction force microscopy in ultrahigh-vacuum conditions, we investigate friction on graphite surfaces with different numbers of free edges as a function of temperature from 295.0 to 100.0 K. We introduce subcontacts formation/rupture simply by changing temperature and tune the out-of-plane deformation compliance by changing the number of free edges. It is found that friction on a plane with large deformation compliance is constantly larger than that with small deformation compliance at cryogenic temperatures. While appearing to be influenced secondly by deformation compliance, the coefficients of friction increase, however, linearly with temperature. By performing systematic stick-slip measurements, the aforementioned separate friction mechanisms have been linked, where the temperature-induced increase of subcontacts rupture force can give rise to the frictional contact quality which additionally becomes more prominent on a plane with large deformation compliance at cryogenic temperatures. These results emphasize a way to vary the contact quality via temperature and demonstrate that the subcontacts formation/rupture and the contact quality must be correlatively accounted for.

Metabolic rates, feed intake, appetite control, and gut transit of clownfish Amphiprion ocellaris exposed to increased temperature and limited feed availability

Episodes of elevated temperature, combined with lower feed availability, are among the predicted scenarios of climate change representing a challenge for coral reef fish. We investigated the response of clownfish (Amphiprion ocellaris) to a scenario in which it received a single meal to satiety after 48 h fasting at 32 °C (climate change scenario) and 28 °C (control). We analysed the metabolic rate (MR), feed intake, gut transit, and expression of selected brain neuropeptides and one receptor believed to be involved in appetite control. Fish at 32 °C ingested 17.9% less feed and had a faster gut transit than did fish at 28 °C. MR in the unfed fish was 31% higher at 32 °C compared to 28 °C. In the fed fish, postprandial MR at 28 °C was 30% higher compared to that of unfed fish, while at 32 °C it was only 15% higher. The expression of agrp1 did not differ between unfed and refed fish. The levels of both pomca and mc4r increased immediately after the meal and subsequently declined, suggesting a possible anorexic role for these genes. Notably, this pattern was accelerated in fish kept at 32 °C compared with that in fish kept at 28 °C. The dynamics of these changes in expression correspond to a faster gut transition of ingested feed at elevated temperatures. For both agrp2 and pomcb there was an increase in expression following feeding in fish maintained at 32 °C, which was not observed in fish kept at 28 °C. These results suggest that low feed availability and elevated temperature stimulate anorexigenic pathways in clownfish, resulting in significantly lower feed intake despite the temperature-induced increase in metabolic rate. This may be a mechanism to ameliorate the decrease in aerobic scope that results from higher temperatures.

Hydrogen Bonding Sequence Directed Coil-Globule Transition in Water Soluble Thermoresponsive Polymers.

The origin of the coil-globule transition for water-soluble thermoresponsive polymers frequently used in nanomaterials remains elusive. Using polypropylene oxide as an example we demonstrate by means of atomistic molecular dynamics simulations that temperature-induced increase in the sequence length of monomers that are not hydrogen bonded to water drives the coil-globule transition. Longer chains statistically exhibit longer sequences which serve as nucleation sites for hydrophobic cluster formation, facilitating chain collapse at lower temperature in agreement with experimental data.

In-situ 4D visualization and analysis of temperature-driven creep in an oil shale propped fracture

The proppant embedment due to creep in shales is a known issue affecting the useable lifetime of wells in unconventional oil and gas recovery. One of the factors influencing creep is the presence of organics, whose properties can be very sensitive to temperature. In this work we investigated for the first time the role of temperature-induced creep increase in proppant embedment in an organics-rich Green River oil shale sample via in-situ synchrotron X-ray micro-computed tomography. We observed that temperatures as low as 75 °C already induce fast creep, with a fracture aperture closing rate of 13 μm/h and a loss of fracture conductivity rate of 8.7%/h, due only to proppant embedment, in the measured interval at the first heating stage. Local displacement data analysis provided evidence for markedly plastic deformation around the proppant-shale contacts, in contrast with the brittle proppant embedment observed on more cemented and less organics-rich shales at room temperature. The results highlight how the problem of temperature-dependent mechanical behavior might be more important than previously thought, in shales with a high content in organics, and that in-situ micro-imaging techniques can play a key role in understanding the underlying mechanisms, contributing to solve creep-related problems associated with hydraulic fracturing in complex scenarios.

Ocean warming and hypoxia affect embryonic growth, fitness and survival of small‐spotted catsharks, Scyliorhinus canicula

Elasmobranchs are key to a healthy marine ecosystem but are under threat from human activities, such as destructive fisheries and shark finning. Embryos of oviparous elasmobranchs may be further challenged during development by rising temperatures and falling dissolved oxygen concentrations in their intertidal environment. However, the impact of climate change on survival and growth of oviparous elasmobranchs is still poorly understood. Here, we investigate the effects of temperature and hypoxia on the growth and survival of small-spotted catshark (Scyliorhinus canicula) embryos by incubating eggs in normoxia 15°C, normoxia 20°C, hypoxia 15°C, or hypoxia 20°C. Incubation under the elevated temperature increased the embryonic growth rate, yolk consumption rate and Fulton's condition factor at hatching, whilst decreasing the total length and body mass of newly hatched sharks. Under low oxygen conditions (50% air saturation) the survival rate of S. canicula embryos dropped significantly and the temperature-induced increase in Fulton's condition factor was reversed. Together, these data demonstrate both the individual and compound effects of elevated temperature and hypoxia on the survival and growth during early ontogeny of a ubiquitous, coastal elasmobranch, S. canicula.

Strength development of cemented tailings materials containing polycarboxylate ether-based superplasticizer: experimental results on the effect of time and temperature

Superplasticizers are widely used in the backfill industry for the improvement of the flow ability of cemented paste backfill (CPB) while keeping water content low. However, the coupled effects of temperature and curing time on the mechanical strength of CPB with superplasticizers are poorly understood. This paper presents new findings of research conducted to experimentally assess the effects of a polycarboxylate-based superplasticizer on the strength of CPB subjected to varying curing time (1, 3, 7, and 28 days) and temperature (2 °C, 20 °C, and 35 °C). The binders used were Portland cement type I, fly ash, and blast furnace slag. Superplasticizer contents of 0, 0.125, and 0.25 percent of the total weight of the CPB were added. Various microstructural analyses and monitoring programs were also conducted to understand the principles behind the patterns in the strength of different CPB samples. The results obtained show that the unconfined compressive strength (UCS) of the CPB containing polycarboxylate-based superplasticizer increases with time. Moreover, the increase in superplasticizer content was observed to improve the UCS of the CPB (0.25% > 0.125% > 0%). The temperature was also observed to play an important role in strength development as the UCS increases with the rise in the curing temperature for all samples. It is also found that the temperature-induced strength increase is more significant for the CPBs that contain the superplasticizer than for those without superplasticizer. It was also observed that the CPB containing superplasticizer maintained a relatively similar strength upon replacing the cement with 50% slag while showing a sharp decline with fly ash. The findings from this study will be useful towards a cost-effective design of backfill structures.

Effects of Temperature and Nutrient Supply on Resource Allocation, Photosynthetic Strategy, and Metabolic Rates of Synechococcus sp.

Temperature and nutrient supply are key factors that control phytoplankton ecophysiology, but theirrole is commonly investigated in isolation. Their combined effect on resource allocation, photosynthetic strategy, and metabolism remains poorly understood. To characterize the photosynthetic strategy and resource allocation under different conditions, we analyzed the responses of a marine cyanobacterium (Synechococcus PCC 7002) to multiple combinations of temperature and nutrient supply. We measured the abundance of proteins involved in the dark (RuBisCO, rbcL) and light (Photosystem II, psbA) photosynthetic reactions, the content of chlorophyll a, carbon and nitrogen, and the rates of photosynthesis, respiration, and growth. We found that rbcL and psbA abundance increased with nutrient supply, whereas a temperature-induced increase in psbA occurred only in nutrient-replete treatments. Low temperature and abundant nutrients caused increased RuBisCO abundance, a pattern we observed also in natural phytoplankton assemblages across a wide latitudinal range. Photosynthesis and respiration increased with temperature only under nutrient-sufficient conditions. These results suggest that nutrient supply exerts a stronger effect than temperature upon both photosynthetic protein abundance and metabolic rates in Synechococcus sp. and that the temperature effect on photosynthetic physiology and metabolism is nutrient dependent. The preferential resource allocation into the light instead of the dark reactions of photosynthesis as temperature rises is likely related to the different temperature dependence of dark-reaction enzymatic rates versus photochemistry. These findings contribute to our understanding of the strategies for photosynthetic energy allocation in phytoplankton inhabiting contrasting environments.

High‐temperature electrical performances and physics‐based analysis of p‐GaN HEMT device

High-temperature electrical performances of enhancement-mode (E-mode) high electron mobility transistor with p-type Gallium Nitride (GaN) gate cap are evaluated here. The physics-based mechanisms behind the behaviours are also analysed by the simulations and analytical models. For static electrical performances, the changes of GaN bandgap and the interface states or traps are considered to be influential factors for the little variations of threshold voltage (VT). Meanwhile, the on-state resistance increases and trans-conductance decreases at high temperatures due to the reduction in electron mobility (µeff). As for blocking characteristic, high temperature-induced increase of leakage current may result from multi-reasons, such as the increase of intrinsic carrier concentration and lowering of trap barrier. In addition, a segmental method is presented to understand the gate leakage current at high temperatures. For capacitance characteristics, the increase of channel resistance makes the measured gate capacitance lower than the intrinsic value. For dynamic electrical performances, the high temperature-induced decrease of µeff leads to the increase of plateau voltage, bringing the decreases of total switching time and total switching energy loss, which are quite different from those of the devices with traditional metal-oxide-semiconductor structures.

High-temperature extensional rheology of linear, branched, and hyper-branched polycarbonates

The high-temperature extensional viscosity of three commercially available linear, branched and hyper-branched polycarbonates (PCs) were measured using a high-temperature capillary breakup extensional rheometer (CaBER) in both air and nitrogen. The experiments were performed at temperatures ranging from T = 250 to 370 °C to a maximum Hencky strain of ten. At lower end of the temperature range, no significant degradation of the linear and branched PC was observed either in the shear or extensional measurements. Beyond, T > 300 °C degradation of the three different PCs was observed. Changes to the molecular structure of the PC were observed which resulted in a dramatic increase in the extensional viscosity. The rate of growth in the extensional viscosity was found to increase with temperature, time at temperature, and, in the case of the linear and branched PC, the presence of air. For the hyper-branched case, changes to the molecular structure of the PC were found to occur more quickly under nitrogen. At these high temperatures, the increase in extensional viscosity was found to grow large enough to stop the breakup of the fluid filament all together, essentially stopping all capillary drainage. This temperature-induced cross-linking and increase in the extensional viscosity of the PC can improve the anti-dripping properties of the polycarbonate by slowing and even restricting dripping from polymeric components near high heat surges. Through these experiments, we have demonstrated measurement of the extensional viscosity to be several orders of magnitude more sensitive to temperature-induced changes to the molecular structure than measurements of shear rheology.

EjHAT1 Participates in Heat Alleviation of Loquat Fruit Lignification by Suppressing the Promoter Activity of Key Lignin Monomer Synthesis Gene EjCAD5.

Texture attributes such as firmness and lignification are important for fruit quality. Lignification has been widely studied in model plants and energy crops, but fruit lignification has rarely been investigated, despite having an adverse effect on fruit quality and consumer preference. Chilling-induced loquat fruit lignification that occurs after harvest can be alleviated by heat treatment (HT) applied prior to low temperature storage. Enzyme activity assay showed that HT treatment could retard the low temperature-induced increase in cinnamyl alcohol dehydrogenase (CAD) activity. Transcript analysis and substrate activity assays of recombinant CAD proteins highlighted the key role of EjCAD5 in chilling-induced lignin biosynthesis. A novel homeobox-leucine zipper protein ( EjHAT1) was identified as a negative regulator of EjCAD5. Therefore, the effect of HT treatment on lignification may be partially due to the suppression of the EjCAD5 promoter activity by EjHAT1.

Equilibrium and Kinetic Unfolding of GB1: Stabilization of the Native State by Pressure.

NMR spectroscopy allows an all-atom view on pressure-induced protein folding, separate detection of different folding states, determination of their population, and the measurement of the folding kinetics at equilibrium. Here, we studied the folding of protein GB1 at pH 2 in a temperature and pressure dependent way. We find that the midpoints of temperature-induced unfolding increase with higher pressure. NMR relaxation dispersion experiments disclosed that the unfolding kinetics slow down at elevated pressure while the folding kinetics stay virtually the same. Therefore, pressure is stabilizing the native state of GB1. These findings extend the knowledge of the influence of pressure on protein folding kinetics, where so far typically a destabilization by increased activation volumes of folding was observed. Our findings thus point toward an exceptional section in the pressure-temperature phase diagram of protein unfolding. The stabilization of the native state could potentially be caused by a shift of p Ka values of glutamates and aspartates in favor of the negatively charged state as judged from pH sensitive chemical shifts.

Low Flow Regimes of the Tarim River Basin, China: Probabilistic Behavior, Causes and Implications

Droughts are a frequent occurrence in Xinjiang, China, and therefore fundamental to determining their hydrologic characteristics is low flow analysis. To that end, 11 probability distribution functions and 26 copulas functions were employed to analyze the changing characteristics of low flow regime (defined as seven-day low flow) of the Tarim River Basin. Results indicated that: (1) The Wakeby distribution satisfactorily described the probabilistic behavior of the low flow regime. According to Akaike Information Criterion (AIC), Bayesian Information Criterions (BIC), maximum likelihood, and other residual-based metrics, Tawn copula, Farlie–Gumbel–Morgenstern copula and Frank copula were the best choice and used in this current study. (2) After 1987, hydrological droughts of longer return periods were prone to higher occurrence frequency. (3) The low flow volume has been increasing in recent years due to the temperature-induced increase of snowmelt and increasing precipitation. However, hydrological droughts can be expected to occur due to the massive increase in water demand from the development of irrigated agriculture, increasing arable land and livestock farming. As a result, the water shortage in the lower Tarim River Basin will be increasingly severe under the influence of climate change and human activities. To alleviate the shortage would call for the development of water-saving agricultural irrigation, water-saving technology, conservation of eco-environment and sustainable development of local socio-economy.

Inferring changes in soil organic matter in post-wildfire soil burn severity levels in a temperate climate

Simple, rapid and reliable methods of assessing soil burn severity (SBS) are required in order to prioritize post-fire emergency stabilization actions. SBS proxies based on visual identification and changes in soil organic matter (SOM) content and quality can be related to other soil properties in order to determine the extent to which soil is perturbed following fire. This task is addressed in the present study by an approach involving the use of differential scanning calorimetry-thermogravimetric analysis (DSC-TGA) to determine changes in SOM generated in soils subjected to different levels of SBS.Intact topsoil monoliths comprising the organic horizons and the surface mineral soil (alumic-humic umbrisols) were collected from a representative P. pinaster stand in NW Spain. The monoliths were experimentally burned in a combustion wind tunnel to simulate different fire conditions (fuel bed comprising forest pine litter and wood; air flow, 0.6 m s−1). Changes in OM properties in the soil organic layer and mineral soils samples (0–2 cm) at the different temperatures and SBS levels were identified.For both duff and mineral soil, the data revealed a temperature-induced increase in aromatic compounds and a concomitant decrease of carbohydrates and alkyl products. However, for a given temperature, the degree of carbonization/aromatization was lower in the mineral soil than in the duff, possibly due to the different composition of the OM and to the different combustion conditions. The low degree of aromatization of the organic matter suggests that this soil component could undergo subsequent biological degradation. SOM content and thermal recalcitrance (measured as T50) discriminated the SBS levels. Use of visual identification of SBS levels in combination with DSC-TGA enables rapid evaluation of the spatial variability of the effects of fire on SOM properties. This information is useful to predict soil degradation process and implement emergency soil stabilization techniques.

Effect of carrier transfer process between two kinds of localized potential traps on the spectral properties of InGaN/GaN multiple quantum wells

Two InGaN/GaN multiple-quantum-well (MQW) samples with identical epitaxial structures are grown at different growth rates via metal-organic chemical vapor deposition system. The room temperature photoluminescence intensity of the fast-grown sample is much stronger than that of the slow-grown one. In addition, the fast-grown sample has two luminescence peaks at low temperatures, and the height of main peak anomalously increases with increasing temperature below 100 K. Such improved emission efficiency and the untypical temperature-induced increase of peak height can be attributed to the carrier's transferring between two kinds of localized traps with different potential depth in the fast-grown sample, where the distribution of indium is seriously inhomogeneous. The enhanced fluctuation of indium is caused by the reduced migration time of adsorbed atoms due to the increased growth rate during the epitaxial growth of MQW region.

Permeability and Selectivity of PPO/Graphene Composites as Mixed Matrix Membranes for CO₂ Capture and Gas Separation.

We fabricated novel composite (mixed matrix) membranes based on a permeable glassy polymer, Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), and variable loadings of few-layer graphene, to test their potential in gas separation and CO2 capture applications. The permeability, selectivity and diffusivity of different gases as a function of graphene loading, from 0.3 to 15 wt %, was measured at 35 and 65 °C. Samples with small loadings of graphene show a higher permeability and He/CO2 selectivity than pure PPO, due to a favorable effect of the nanofillers on the polymer morphology. Higher amounts of graphene lower the permeability of the polymer, due to the prevailing effect of increased tortuosity of the gas molecules in the membrane. Graphene also allows dramatically reducing the increase of permeability with temperature, acting as a “stabilizer” for the polymer matrix. Such effect reduces the temperature-induced loss of size-selectivity for He/N2 and CO2/N2, and enhances the temperature-induced increase of selectivity for He/CO2. The study confirms that, as observed in the case of other graphene-based mixed matrix glassy membranes, the optimal concentration of graphene in the polymer is below 1 wt %. Below such threshold, the morphology of the nanoscopic filler added in solution affects positively the glassy chains packing, enhancing permeability and selectivity, and improving the selectivity of the membrane at increasing temperatures. These results suggest that small additions of graphene to polymers can enhance their permselectivity and stabilize their properties.