Chemical Aging Research Articles

Aging of α-Pinene Secondary Organic Aerosol by Hydroxyl Radicals in the Aqueous Phase: Kinetics and Products.

The reaction of hydroxyl radicals (OH) with a water-soluble fraction of the α-pinene secondary organic aerosol (SOA) was investigated using liquid chromatography coupled with negative electrospray ionization mass spectrometry. The SOA was generated by the dark ozonolysis of α-pinene, extracted into the water, and subjected to chemical aging by the OH. Bimolecular reaction rate coefficients (kOH) for the oxidation of terpenoic acids by the OH were measured using the relative rate method. The unaged SOA was dominated by the cyclobutyl-ring-retaining compounds, primarily cis-pinonic, cis-pinic, and hydroxy-pinonic acids. Aqueous oxidation by the OH resulted in the removal of early-stage products and dimers, including well-known oligomers with MW = 358 and 368 Da. Furthermore, a 2- to 5-fold increase in the concentration of cyclobutyl-ring-opening products was observed, including terpenylic and diaterpenylic acids and diaterpenylic acid acetate as well as some of the newly identified OH aging markers. At the same time, results obtained from the kinetic box model showed a high degree of SOA fragmentation following the reaction with the OH, which indicates that non-radical reactions occurring during the evaporation of water likely contribute to the high yields of terpenoic aqSOAs reported previously. The estimated atmospheric lifetimes showed that in clouds, terpenoic acids react with the OH exclusively in the aqueous phase. Aqueous OH aging of the α-pinene SOA results in a 10% increase of the average O/C ratio and a 3-fold decrease in the average kOH value, which is likely to affect the cloud condensation nuclei activity of the aqSOA formed after the evaporation of water.

Late Paleoproterozoic deposition and Mesoproterozoic metamorphism of detrital material in the southernmost Baltic Sea region (Gdańsk IG1 borehole): monazite versus zircon and chemical versus isotopic age record

ABSTRACT The SHRIMP ion microprobe zircon and monazite U–Th–Pb isotope geochronology of a biotite-sillimanite paragneiss derived from the Gdańsk IG1 borehole that penetrated the Precambrian basement in the southernmost Baltic Sea area, northern Poland, has constrained the ages of detrital zircon cores and metamorphic overgrowths. In addition, monazites have been dated by electron beam chemical technique either as a grain separate or in thin sections. The metasediments show a specific provenance pattern with a dominant input from the late Paleoproterozoic sources. The ages range from 2749 to 1643 Ma with peaks at 1779, 1815, 1840 and 1870 Ma. The maximum depositional age, defined by the youngest detrital zircons, was determined at 1643 Ma. Zircon rims and monazite isotope analyses record a metamorphic event at 1485, and 1498 Ma, respectively, whereas Th–U–Pb chemical dating on monazite revealed an age of 1494 Ma. These ages correspond with the time of the AMCG magmatism in the basement of northern Poland. The metamorphic monazite predates the age of the zircon rims by over 10 m.y. This discrepancy is likely caused by the different behavior of the two accessories since the zircon metamorphic crystallization requires fluid/melt-related support. Thus, zircon is not expected to record the time of peak metamorphism. In consequence, monazite tends to be a more sensitive metamorphic geochronometer. Moreover, the EPMA method provides greater spatial resolution. Additional older fragments, with ages of 1539, 1596, 1600 and 1620 Ma, were identified within monazites reflecting earlier stages of metamorphic evolution.

A new point to correlate the multi-dimensional assessment for the aging process of microfibers

Fiber, the most prevalent plastic type, can be weathered and eroded easily in the natural environment. Although a variety of techniques have been applied to characterize the aging characteristics of plastics, a comprehensive understanding was critically essential to correlate the multi-dimensional assessment of the weathering process of microfibers and their environmental behavior. Therefore, in this study, microfibers were prepared from the face masks and Pb2+ was selected as a typical metal pollutant. The weathering process was simulated by xenon aging and chemical aging, and then subjected to Pb2+adsorption to examine the effect of weathering processes. The changes in fiber property and structure were detected by using various characterization techniques, with the development of several aging indices to quantify the changes. The two-dimensional Fourier transform infrared correlation spectroscopy analysis (2D‐FTIR‐COS) and Raman mapping were also performed to understand the order of changes in the surface functional groups of the fiber. The results showed that both aging processes altered the surface morphology, physicochemical properties, and polypropylene chain conformations of the microfibers, with stronger effect after chemical aging. The aging process also enhanced the affinity of microfiber to Pb2+. Moreover, the changes and correlation of the aging indices were analyzed, showing that the maximum adsorption capacity (Qmax) was positively related to carbonyl index (CI), oxygen-to-carbon atom (O/C) ratio and intensity ratio of the Raman peaks (I841/808), but negatively related to contact angle and the temperature at the maximum weight loss rate (Tm). The O/C ratio was more suitable to quantify the surface changes with lower aging degree while the CI value explained the chemical aging process better. Overall, this study discussed the weathering processes of microfibers based on a multi-dimensional investigation, and attempted to correlate the aging characteristics of the microfibers and their environmental behavior.

Future Directions for Applications of Bio-Oils in the Asphalt Industry: A Step to Sequester Carbon in Roadway Infrastructure

The global emphasis on sustainability and net zero carbon roads combined with the increased cost of crude oil has necessitated the application of new environmentally friendly alternatives to the bitumen used in asphalt by the pavement industry. Physical aging, chemical aging, and moisture damage are three important matters encountered in the pavement industry that are harmful for asphalt; bio-oils can decelerate the rates of physical aging and chemical aging in virgin bitumen, and bio-oils can substantially improve virgin bitumen’s resistance to moisture damage. Bio-oils can also restore properties in environmentally damaged asphalt up to a certain limit of aging. The main goal of this review is a comprehensive analysis of the literature about the potential of bio-oils produced from different biomass sources to influence the physical aging, chemical aging, and moisture damage of asphalt. Considering that bitumen’s physical aging is highly impacted by the bitumen’s wax content, this review also covers the effect of wax inherently present in bitumen or wax added to bitumen as a modifier. It is concluded that the chemical composition of a bio-oil has a significant impact on the bio-oil’s ability to protect or recover the bitumen’s original properties. Phenolic compounds found in bio-oils have antiaging effects while bio-oils’ acidic compounds may lead to moisture susceptibility.According to the literature, most bio-oils have positive effects only in a specific range of temperatures: low, intermediate, or high. Complete miscibility and dispersion of a bio-oil in the asphalt matrix also have a significant influence on making a bio-oil an effective modifier. Generally, bio-oils are promising as sustainable, carbon-neutral, cost-effective alternatives to replace or modify conventional bitumen in the pavement industry. This review has identified the following critical research gaps: (1) the lack of standard methods for evaluating and reporting the performance characteristics of each bio-oil in bitumen; (2) the lack of long-term field performance data on bio-oils to support comprehensive life-cycle assessments and life-cycle analyses; (3) high variation among bio-oils made from the same feedstock through different processing methods, leading to variation in performance characteristics; (4) the lack of accurate technoeconomic analysis on industrial bio-oils to facilitate entry of bio-oils into the asphalt market.

New sight of microplastics aging: Reducing agents promote rapid aging of microplastics under anoxic conditions

The aging of microplastics (MPs) occurs extensively in the environment, and understanding the aging mechanisms of MPs is essential to study the properties, fate and environmental impact of MPs. We proposed a creative hypothesis that polyethylene terephthalate (PET) can be aged by reducing reactions with reducing agents. Simulation experiments based on the principle of reduction of carbonyl by NaBH4 were conducted to test the correctness of this hypothesis. The results showed that after 7 days of experiments, physical damage and chemical transformation occurred in the PET-MPs. The particle size of MPs was reduced by 34.95–55.93 %, and the C/O ratio was increased by 2.97–24.14 %. The changing order of surface functional groups (CO > C-O > C-H > C-C) was obtained. The occurrence of reductive aging and electron transfer of MPs was further supported by electrochemical characterization experiments. These results together reveal the reductive aging mechanism of PET-MPs: CO is firstly reduced to C-O by BH4- attack, and then further reduced to ·R. The resulting ·R recombines to form new C-H and C-C. This study is beneficial to deepen the understanding of the chemical aging of MPs, and can provide a theoretical basis for further research on the reactivity of oxygenated MPs with reducing agents.

Effect of different aging treatments on the transport of nano-biochar in saturated porous media

Widely used for soil amendment, carbon sequestration, and remediation of contaminated soils, biochars (BCs) inevitably produce a large number of nanoparticles with relatively high mobility. Geochemical aging alters chemical structure of these nanoparticles and thus affect their colloidal aggregation and transport behavior. In this study, the transport of ramie derived nano-BCs (after ball-milling) was investigated by different aging treatments (i.e., photo (PBC) and chemical aging (NBC)) as well as the managing BC under different physicochemical factors (i.e., flow rates, ionic strengths (IS), pH, and coexisting cations). Consequences of the column experiments indicated aging promoted the mobility of the nano-BCs. Compared to the nonaging BC, consequences of spectroscopic analysis demonstrated the aging BCs exhibited a number of tiny corrosion pores. Both of these aging treatments contribute to a more negative zeta potential and a higher dispersion stability of the nano-BCs, which is caused by the abundance of O-functional groups. Also the specific surface area and mesoporous volume of both aging BCs increased significantly, with the increase being more pronounced for NBC. The breakthrough curves (BTCs) obtained for the three nano-BCs were modelled by the advection-dispersion equation (ADE), which included first-order deposition and release terms. The ADE revealed high mobility of aging BCs, which meant their retention in saturated porous media was reduced. This work contributes to a comprehensive understanding of the transport of aging nano-BCs in the environment.

The Environmental Conditions, Treatments, and Exposures Ontology (ECTO): connecting toxicology and exposure to human health and beyond

BackgroundEvaluating the impact of environmental exposures on organism health is a key goal of modern biomedicine and is critically important in an age of greater pollution and chemicals in our environment. Environmental health utilizes many different research methods and generates a variety of data types. However, to date, no comprehensive database represents the full spectrum of environmental health data. Due to a lack of interoperability between databases, tools for integrating these resources are needed. In this manuscript we present the Environmental Conditions, Treatments, and Exposures Ontology (ECTO), a species-agnostic ontology focused on exposure events that occur as a result of natural and experimental processes, such as diet, work, or research activities. ECTO is intended for use in harmonizing environmental health data resources to support cross-study integration and inference for mechanism discovery.Methods and findingsECTO is an ontology designed for describing organismal exposures such as toxicological research, environmental variables, dietary features, and patient-reported data from surveys. ECTO utilizes the base model established within the Exposure Ontology (ExO). ECTO is developed using a combination of manual curation and Dead Simple OWL Design Patterns (DOSDP), and contains over 2700 environmental exposure terms, and incorporates chemical and environmental ontologies. ECTO is an Open Biological and Biomedical Ontology (OBO) Foundry ontology that is designed for interoperability, reuse, and axiomatization with other ontologies. ECTO terms have been utilized in axioms within the Mondo Disease Ontology to represent diseases caused or influenced by environmental factors, as well as for survey encoding for the Personalized Environment and Genes Study (PEGS).ConclusionsWe constructed ECTO to meet Open Biological and Biomedical Ontology (OBO) Foundry principles to increase translation opportunities between environmental health and other areas of biology. ECTO has a growing community of contributors consisting of toxicologists, public health epidemiologists, and health care providers to provide the necessary expertise for areas that have been identified previously as gaps.

Evaluating the ageing degrees of bitumen by rheological and chemical indices

The ageing of bitumen is an inevitable phenomenon which is still challenging to be characterised. This paper aims at evaluating the ageing degrees of bitumen comprehensively. There were six types of bitumen being aged to five levels for comparing purposes and multiple rheological tests by a DSR as well as chemical test for the SARA (saturates, aromatics, resins and asphaltenes) properties of bitumen were carried out. The critical temperatures, G-R parameter and nonrecoverable-compliance-based ageing indices were proposed to evaluate the ageing degrees of bitumen in terms of low-, intermediate- and high-temperature performance of bitumen, respectively. Also, a novel ageing evaluation index based on the integration of modulus of master curves was employed and modified, which can evaluate the ageing degrees of bitumen accurately in terms of the whole range of temperature. Finally, the chemical ageing index were analysed and was confirmed to have strong linear relationship with rheological indices of bitumen.

Biaxial flexural strength of different provisional restorative materials under chemo-mechanical aging: An in vitro study.

Durability is a critical factor for the success of long-term provisional restorations. This study evaluated the effect of different storage media and cyclic loading on the biaxial flexural strength of different types of provisional materials. Discs (N=360, 10×2mm) were prepared from different provisional materials; conventional (Protemp 4, Tuff-Temp, Tempron), CAD-CAM milled (VITA CAD-Temp, breCAM.multiCOM), and 3D-printed (Nextdent C&B MFH) (n=60). Each material group was subdivided into four subgroups according to the storage media (n=15): nonaged, artificial saliva, mouthwash, and coffee. The specimens in storage media were placed in an incubator at 37°C for 4 weeks followed by 60,000 simulated chewing cycles. Biaxial flexural strength test was done. Data were analyzed using two-way ANOVA. Weibull distribution parameters were estimated. Both the material and aging protocol showed a significant effect on the biaxial flexural strength. Both Protemp 4 and Nextdent C&B MFH showed a significantly higher biaxial flexural strength before and after aging compared to all other materials. Protemp 4 and Tuff Temp showed a significant decrease in strength with aging. CAD-CAM materials showed higher Weibull moduli. The 3D-printed polymethylmethacrylateprovisional material presents with both greater biaxial flexural strength and increased durability against chemical and mechanical aging compared to conventional and CAD-CAM milled provisional materials tested.

Characterizing the binding interactions between virgin/aged microplastics and catalase in vitro

Microplastics (MPs) undergo physical, chemical, and biological aging in the environment, leading to changes in their physicochemical properties, affecting migration characteristics and toxicity. Oxidative stress effects induced by MPs in vivo have been extensively studied, but the toxicity difference between virgin and aged MPs and the interactions between antioxidant enzymes and MPs in vitro have not been reported yet. This study investigated the structural and functional changes of catalase (CAT) induced by virgin and aged PVC-MPs. It was shown that light irradiation aged the PVC-MPs, and the aging mechanism was photooxidation, resulting in a rough surface and appearing holes and pits. Because of the changes in physicochemical properties, aged MPs had more binding sites than virgin MPs. Fluorescence and synchronous fluorescence spectra results suggested that MPs quenched the endogenous fluorescence of CAT and interacted with tryptophane and tyrosine residues. The virgin MPs had no significant effect on the skeleton of CAT, while the skeleton and the polypeptide chains of CAT became loosened and unfolded after binding with the aged MPs. Moreover, the interactions of CAT with virgin/aged MPs increased the α-helix and decreased the β-sheet contents, destroyed the solvent shell, and resulted in a dispersion of CAT. Due to the large size, MPs cannot enter the interior of CAT and have no effects on the heme groups and activity of CAT. The interaction mechanism between MPs and CAT may be that MPs adsorb CAT to form the protein corona, and aged MPs had more binding sites. This study is the first comprehensive investigation of the effect of aging on the interaction between MPs and biomacromolecules and highlights the potential negative effects of MPs on antioxidant enzymes.

Chemical aging of sealing gasket of proton exchange membrane fuel cell

AbstractAs the key sealing part of proton exchange membrane fuel cell (PEMFC), the gasket is easily damaged in acidic solution and wet air for a long time in PEMFC, resulting in unsafe and unstable operation of PEMFC. In this paper, the regular solution (RS) and accelerated durability test (ADT) solution in PEMFC were prepared to study the aging damage process of silicone rubber gasket, and the attenuated total reflection Fourier transform infrared spectrometer (ATR‐FTIR) was used to analyze the surface changes of gaskets soaked in solutions. The results showed that the weight loss of samples increased with the soaking time in both ADT solution and RS solution, and the damage of samples in ADT solution was faster and more serious than that in RS solution. Meanwhile, the microstructure diagram also indicated that the damage of the samples in ADT solution was more serious than that in the RS solution. The ATR‐FTIR analysis results showed that the intensity of characteristic wave peaks of samples at 706, 787, 867, 1006, 1071, 1260, and 2961cm−1 in ADT solution decreased faster than that in RS solution, which was consistent with the results of weight analysis and microstructure analysis.

Antiaging Effects of Linear Alkyl Benzene Sulfonic Acid Utilization on Bitumen Modification

The manufacture of asphalt pavements causes various environmental problems due to bitumen’s hazardous nature. Aging of bitumen yields undesirable properties, which may cause several adverse effects on asphalt performance. Use of antiaging agents for bitumen modification results in improved aging resistance, hence such agents confer environmental benefits by reducing the consumption of bitumen owing to lower maintenance requirements and the reduced volume that needs to be produced. Therefore, it is important to develop new antiaging agents and investigate their benefits to the asphalt industry. This study investigated the use of different rates (1%, 2%, and 3%) of linear alkyl benzene sulfonic acid (LABSA) as a bitumen antiaging agent through chemical and rheological characterization on unaged, short-term-aged, and long-term-aged samples using Fourier transform infrared spectroscopy and dynamic shear rheometer (DSR). A chemical aging index (CAI) and various rheological aging indexes, obtained by the construction of master curves and crossover temperatures were calculated to evaluate the variation of aging effects by LABSA addition. The detailed experiments showed that LABSA-modified samples exhibited better aging resistance compared to neat (base) bitumen. Additionally, the statistical analyses of all aging indexes were investigated to obtain the relationship between chemical and rheological aging indexes. The determination coefficient (R2) and scatter index (SI) results showed that the rheological behavior of bitumen against aging could be evaluated based on chemical behavior and vice versa. Moreover, it was concluded that short-term aging and long-term aging effects should be evaluated separately to determine the relationship between different aging characteristics of samples.

Investigation of the Functional Ageing of Conductive Coated Fabrics under Simulated Washing Conditions.

Conductive textiles play an important role in recent electronics development; however, one of the major challenges remains their machine-washing durability. For the investigation of the basic wash ageing mechanisms, we used copper-plated polyamide 66 and cellulose fabrics and developed a wet and dry operable flex tester with online resistance recording. The evaluation was supported by abrasion tests, cyclic elongation tests and tribological investigation of dry and wet textile-textile friction. It was found that the contribution of mechanical and chemical ageing to wash ageing strongly depends on the substrate material. A bad adhesion of copper on polyamide 66 leads to early fatigue while better stability of the copper on cellulose leads to a stronger resistance against ageing. For both substrates, the delamination of the copper layer was the root cause of the fatigue, which is facilitated by the washing solution. Finally, a cumulative fatigue model was developed and the determination of the end of lifetime by the intended use is discussed.

The importance of outlier rejection and significant explanatory variable selection for pinot noir wine soft sensor development

Sensory attributes are essential factors in determining the quality of wines. However, it can be challenging for consumers, even experts, to differentiate and quantify wines' sensory attributes for quality control. Soft sensors based on rapid chemical analysis offer a potential solution to overcome this challenge. However, the current limitation in developing soft sensors for wines is the need for a significant number of input parameters, at least 12, necessitating costly and time-consuming analyses. While such a comprehensive approach provides high accuracy in sensory quality mapping, the expensive and time-consuming studies required do not lend themselves to the industry's routine quality control activities. In this work, Box plots, Tucker-1 plots, and Principal Component Analysis (PCA) score plots were used to deal with output data (sensory attributes) to improve the model quality. More importantly, this work has identified that the number of analyses required to fully quantify by regression models and qualify by classification models can be significantly reduced. Based on regression models, only four key chemical parameters (total flavanols, total tannins, A520nmHCl, and pH) were required to accurately predict 35 sensory attributes of a wine with R2 values above 0.6 simultaneously. In addition, for classification models to accurately predict 35 sensory attributes of a wine at once with prediction accuracy above 70%, only four key chemical parameters (A280nmHCl, A520nmHCl, chemical age and pH) were required. These models with reduced chemical parameters complement each other in sensory quality mapping and provide acceptable accuracy. The application of the soft sensor based on these reduced sets of key chemical parameters translated to a potential reduction in analytical cost and labour cost of 56% for the regression model and 83% for the classification model, respectively, making these models suitable for routine quality control use.

Heat loss effect on bitumen ageing in tanks

The article is devoted to laboratory research on the influence of convective motion as a result of thermal losses and their compensation in tanks on the physical and chemical ageing of bitumen BND 60/90 and BND 90/130. Laboratory tests of bitumen samples confirmed the hypothesis about the key role of free movement of bitumen in tanks on its degradation under conditions of maintaining operating temperatures and free air access. Thus, bitumen degradation has a functional relationship with thermal losses from the tank surface and the total energy input for bitumen heating.

Preferential destruction of NH2-bearing complex interstellar molecules via gas-phase proton-transfer reactions.

Complex, nitrogen-bearing interstellar molecules, especially amines, are targets of particular interest for detection in star- and planet-forming regions, due to their possible relevance to prebiotic chemistry. However, these NH2-bearing molecules are not universally detected in sources where other, oxygen-bearing complex organic molecules (COMs) are often plentiful. Nevertheless, recent astrochemical models have often predicted large abundances for NH2-bearing complex organics, based on their putative production on dust grains. Here we investigate a range of new gas-phase proton-transfer reactions and their influence on the destruction of COMs. As in past studies, reactions between protonated COMs and ammonia (NH3) are found to be important in prolonging gas-phase COM lifetimes. However, for molecules with proton affinities (PA) greater than that of ammonia, proton-transfer reactions result in drastic reductions in abundances and lifetimes. Ammonia acts as a sink for proton transfer from low-PA COMs, while passing on protons to high-PA species; dissociative recombination with electrons then destroys the resulting ions. Species strongly affected include methylamine (CH3NH2), urea (NH2C(O)NH2) and others bearing the NH2 group. The abundances of these species show a sharp time dependence, indicating that their detectability may rest on the precise chemical age of the source. Rapid gas-phase destruction of glycine (NH2CH2COOH) in the models suggests that its future detection may be yet more challenging than previously hoped.

Durability Evaluation of Outdoor Scrimbers Fabricated from Superheated Steam-Treated Bamboo Fibrous Mats

With natural texture and high performance, bamboo scrimber is one of the artificial lignocellulosic composites widely used in construction, furniture and other structural applications. However, it is vulnerable to the actions of water, ultraviolet radiation and fungus, which affect its durability, especially in the open. Here, bamboo was treated with superheated steam in an attempt to improve the durability of bamboo scrimbers. The chemical composition, mechanical properties, dimensional stability, aging resistance, decay resistance and anti-mildew properties were investigated at different temperatures (160~200 °C). After superheated steam treatment, the relative contents of holocellulose and α-cellulose in bamboo decreased. The bending strength and short-beam shearing strength slightly decreased as the temperature was raised while the modulus was essentially retained. The aging resistance in terms of thickness swelling rate (≤9.38%) was substantially improved. The decay resistance reached to the level of Grade I and can be dramatically enhanced by elevating temperature. The anti-mildew properties were also improved. To take together, superheated steam treatment remarkably improves the resistance of bamboo scrimbers to water, ultraviolet radiation, rot fungi and mildew with some concomitant reduction in mechanical properties. The results will permit outdoor construction using bamboo scrimbers more resistant to environmental damage.

Effect of chemical ageing on fatigue life of short glass fiber-reinforced Polyamide 6,6

In this study, the effect of hydrolysis and oxidation on fatigue life of Polyamide 6,6 reinforced with 30 wt% glass fibers has been studied systematically for the first time. The chemical changes due to these two chemical processes were monitored, especially the molar mass decrease over ageing time, homogeneous throughout the sample for hydrolysis and localized in a near-surface layer for oxidized samples. In both cases the fatigue life was significantly decreased with ageing. For homogeneously aged samples, the maximal applied stress at a given number of cycles to failure was correlated to the decrease of the molar mass of the matrix using a Flory-based model. This leads to the definition of a critical molar mass around 13 kg/mol which can be linked to the molar mass between entanglements, suggesting that fatigue is governed by fracture occurring in the glassy amorphous phase. To explain the decrease in fatigue life for oxidized heterogeneous samples, we proposed that a brittle layer, smaller than the oxidized layer itself, is considered as not sustaining any stress. The existence of this brittle layer was confirmed by fracture surface analysis and found in good agreement with the values extracted from the analytical model proposed.

New Horizons for Estimating the Time Since Deposition of Fingermarks: Combining Label-Free Physical Visualization and Electrochemical Characterization.

The time since deposition (TSD) of latent fingermarks (LFMs) serves as "witnesses" for crime scene reconstructions. Nevertheless, existing TSD prediction approaches focused on either physical or chemical aging parameters leading to inaccurate estimation. A novel label-free protocol has been developed, where both physical ridge patterns and lipid oxide (LipOx) degradation kinetics are realized using optical microscopy and scanning electrochemical microscopy (SECM) and combined for TSD prediction. Specifically, the surface interrogation (SI)-SECM titration was utilized to monitor the LipOx degradation in LFM arrays aligned by hole array masks, through which we derived the LipOx degradation function. After establishing the relationship between several titration parameters and titrated area by experimental and numerical simulation methods, the titrated area could be reasonably estimated and subsequently used to calculate the surface coverage of LipOx. Results demonstrated that the tip transient revealed the LipOx coverage of deposited LFMs. Notably, LipOx coverage was found to increase during the first day and then decrease over time, whose degradation rate was susceptible to light. Thus, TSD candidates of an LFM could be limited to two values through the established function. Due to the nonmonotonic trend of LipOx aging, a physical parameter "the gray value ratio (GVR) of furrows to ridges" was proposed to exclude irrelevant TSD through support vector machine (SVM) classification. Ultimately, we predicted TSDs of seven LFMs with estimation errors of 2.2-26.8%. Overall, our strategy, with the outperformed capability of gleaning physical and electrochemical information on LFMs, can provide a truly label-free way of studying LFMs and hold great promise for multidimensional fingerprint information analysis.

Effects of physical and chemical ageing on 3D printed poly (ether ether ketone)/poly (ether imide) [PEEK/PEI] blend for aerospace applications

Effects of physical and chemical ageing on 3D printed poly (ether ether ketone)/poly (ether imide) [PEEK/PEI] blend for aerospace applications