Graphite Loading Research Articles

One-Step Fabrication of Semi-Transparent Nanofibrous Lithium-Ion Battery

Flexibility and transparency of batteries greatly expand their application and offer new opportunities to electronic devices making them foldable, bendable, and not obstracting. Herein was proposed a facile and beneficial strategy to solve “hot” issues of such type of batteries by providing a uniform and stable framework for bendable, portable and semi-transparent "all-in-one" lithium-ion batteries (LIBs). The “all-in-one” flexible LIB was fabricated by one-stage electrospinning of PEO and PVDF-HFP-based precursor solution loaded with active materials. The electrochemical performance of the anode and cathode membranes was investigated in lithium half cells. To improve the electron-conductivity, CNTs were introduced inside the nanofibers in anode and cathode parts. The nanofibers containing active materials were successfully fabricated with the use of pre-synthesized nanosized LFP/C and graphite powders and loading them into the electrospinning solutions of the cathode and anode, respectively. The use of the same polymer to produce all three parts of the battery (anode, separator and cathode), as well as optimized electrospinning conditions, made it possible to obtain all-in-one flexible solo membrane. The concept was based on the application of nanofibers containing pre-synthesized active materials without carbonization, sintering or any other post-treatment. The developed “all-in-one” membrane assembled within copper and nickel meshes acting as anodic and cathodic current collectors demonstrated semi-transparency as can be seen from the figure. It is enabled by the swollen polymer fibers network, which provides transparent substrate for nano-sized particles of active materials. Additionally, the thin metallic mesh used as current collectors could maintain the overall transparency of the cell. Alternatively ITO glass and/or membrane with high content of CNT were used as a current collectors to provideimproved transparency and flexibility. Acknowledgment This research is funded by the Committee of Science of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. BR21882402) Figure 1

Optimised graphite/carbon black loading of recycled PLA for the production of low-cost conductive filament and its application to the detection of β-estradiol in environmental samples

The production, optimisation, physicochemical, and electroanalytical characterisation of a low-cost electrically conductive additive manufacturing filament made with recycled poly(lactic acid) (rPLA), castor oil, carbon black, and graphite (CB-G/PLA) is reported. Through optimising the carbon black and graphite loading, the best ratio for conductivity, low material cost, and printability was found to be 60% carbon black to 40% graphite. The maximum composition within the rPLA with 10 wt% castor oil was found to be an overall nanocarbon loading of 35 wt% which produced a price of less than £0.01 per electrode whilst still offering excellent low-temperature flexibility and reproducible printing. The additive manufactured electrodes produced from this filament offered excellent electrochemical performance, with a heterogeneous electron (charge) transfer rate constant, k0 calculated to be (2.6 ± 0.1) × 10−3 cm s−1 compared to (0.46 ± 0.03) × 10−3 cm s−1 for the commercial PLA benchmark. The additive manufactured electrodes were applied to the determination of β-estradiol, achieving a sensitivity of 400 nA µM−1, a limit of quantification of 70 nM, and a limit of detection of 21 nM, which compared excellently to other reports in the literature. The system was then applied to the detection of ß-estradiol within four real water samples, including tap, bottled, river, and lake water, where recoveries between 95 and 109% were obtained. Due to the ability to create high-performance filament at a low material cost (£0.06 per gram) and through the use of more sustainable materials such as recycled polymers, bio-based plasticisers, and naturally occurring graphite, additive manufacturing will have a permanent place within the electroanalysis arsenal in the future.Graphical abstract

An experimental study on the effect of graphite microparticles on the mechanical and tribological properties of epoxy matrix composites

This article comprehensively discusses the mechanical and tribological properties of epoxy matrix composites filled with 100μm graphite particulates, at loadings ranging from 0 to 1wt%. The investigation also focuses on the effects of the graphite filler on the wear surface of the specimens, utilizing an optical microscope for analysis. The results revealed a significant decrease in the tensile strength of the composite, with a reduction of more than 50% observed at 1wt% graphite loading. However, the flexural strength exhibited an initial sharp increase at 0.1wt% graphite loading, followed by a decline at higher graphite contents. Moreover, both impact and hardness values demonstrated improvement as the graphite content increased. The addition of graphite particles led to a reduction in the friction coefficient, attributed to the solid lubrication capabilities of graphite. Furthermore, the wear rate exhibited a sharp decrease with an increase in graphite content due to the formation of a lubrication layer at the contact surface, effectively reducing the break-off of the specimen.

Electrically Conductive Natural Rubber Composite Films Reinforced with Graphite Platelets.

Green natural rubber (NR) composites reinforced with synthetic graphite platelets, using alginate as a thickening and dispersing agent, were successfully developed to improve mechanical properties, chemical resistance, and electrical conductivity. The fabrication was performed using a latex aqueous microdispersion process. The research demonstrated the effective incorporation of graphite platelets into the NR matrix up to 60 parts per hundred rubbers (phr) without causing agglomeration or phase separation. Graphite incorporation significantly improved the mechanical strength of the composite films. NR with 60 phr of graphite exhibited the highest Young's modulus of 12.3 MPa, roughly 100 times that of the neat NR film. The reinforcement also strongly improved the hydrophilicity of the composite films, resulting in a higher initial water absorption rate compared to the neat NR film. Moreover, the incorporation of graphite significantly improved the chemical resistance of the composite films against nonpolar solvents, such as toluene. The composite films exhibited biodegradability at about 21% to 30% after 90 days in soil. The electrical conductivity of the composite films was considerably enhanced up to 2.18 × 10-4 S/cm at a graphite loading of 60 phr. According to the improved properties, the developed composites have potential applications in electronic substrates.

Aminated silver nanowires as current collectors and binders for the preparation of multilayer graphite loading high-performance silk fiber electrodes

The rapid development of wearable electronic devices has put forward high requirements for their energy storage devices. Currently, fiber supercapacitors have attracted widespread attention owing to their miniature sizes and high flexibility, but an improvement in their electrochemical performance is often limited by the loading of conductive energy storage materials. Herein, a multilayer graphene loading strategy based on amino silver nanowires (NH2-AgNWs) was developed to prepare silk electrodes, wherein NH2-AgNWs were used as current collectors and binders to increase the conductivity of silk electrodes and achieve multilayer loading graphene on silk. The prepared silk electrode exhibited a high specific capacitance of 37.14 mF/cm because of the multilayer loading of the conductive energy storage material. The generality of this method is further demonstrated with a cotton thread substrate electrode, which exhibited a specific capacitance of 69.45 mF/cm. Additionally, a parallel fiber-shaped supercapacitor (PFSS) was assembled, at the maximum power density of 74.48 mW/m2, the energy density reaches 1468.87 mWh/m2. The PFSS exhibited a capacitance retention rate of 93.01 % when the bending degree was 90°. This study proposes a multilayer graphene loading strategy based on NH2-AgNWs for the preparation of fiber electrodes and a flexible fiber supercapacitor was assembled.

STUDY OF THE PROCESS OF OBTAINING A COMPOSITE MATERIAL "SPHERICAL GRAPHITE – Fe2O3"

In this article, a study was conducted on the process of obtaining a composite material “spherical graphite – iron oxide”, with the aim of its further use as an anode material for lithium-ion batteries. The composite was obtained by depositing iron oxide nanoparticles on the surface of spherical graphite. The influence of the deposition process parameters on the physico-chemical properties of the composite has been studied. It was found that the following factors have a significant effect on the final properties of the composite: the nature of the precipitator, the density of graphite loading of the precipitation working solution, the aging time of the system, the ratio of di- and trivalent iron in solution. Solutions of ammonia and urea were studied as precipitators. In the case of using urea, the formation of iron oxide particles with smaller coherent scattering regions, that is, with smaller crystallite sizes, was noted. Amorphous Fe2O3 precipitates are more preferable in terms of using them as an anode material. With an increase in the loading density of the graphite deposition solution, an increase in the yield of iron oxide nanoparticles was observed, however, at loading densities above 15 g/l, large iron oxide aggregates were formed. With an increase in the aging time of the deposition system, an improvement in the distribution of iron oxide nanoparticles over the surface of spherical graphite and a decrease in nanoparticle aggregates were noted. An increase in the molar fraction of Fe2+ in the precipitation solution has a similar effect. Based on the experimental data obtained, the optimal modes of the iron oxide deposition process were determined. Under these conditions, a sample of spherical graphite coated with Fe2O3 nanoparticles with average particle sizes of 30-50 nm was obtained. The oxide content in the sample was 3.7%. Electrochemical studies of the lithium-ion battery layout have shown that spherical graphite modified with iron oxide shows a reversible capacity increased to 370 mA∙h/g and greater stability of work.

High Performance Anode Binder

Binders are inactive but necessary component of the electrodes and without using a proper binder, the performance of LIBs would prematurely degrade. A well-designed binder allows to increase the electrode energy density by reducing the binder demand, as well as increasing the cycle-life by maintaining an adequate mechanical integrity and ionic mobility within the electrode.This poster will present a newly designed high-performance anode binder by Arkema. IncellionTM EL 1061 is a high purity WB binder, could overcome the limitations of traditional binders, and allows to maximizing the performance of conventional anodes –including graphite loading of > 97%, first cycle efficiency of > 93%, high C-rate capability of 2C/0.2C of > 96.5%, and capacity retention of > 92% after 500-cycles in 18650 cells- without a need to change the anode design. Moreover, double-sided anodes of > 35 mg/cm2 loadings were successfully fabricated using this high-performance binder and tested in 75 Ah high energy density pouch cells needed for demanding applications.

Recyclable ammonia uptake of CuCl2/graphite composite adsorbents with high adsorption capacity

Ammonia is considered a good hydrogen storage material due to its advantages of high hydrogen content density. At the same time, the characteristic of efficient heat transfer of ammonia makes it develop rapidly in many energy industries. However, unutilized NH3 can cause corrosion and poisoning, therefore, NH3 must be captured in time. Metal chloride is a green, efficient and sustainably utilized material for NH3 adsorption and capture. In this paper, a novel composite adsorbent was proposed by loading graphite to CuCl2 to enhance the NH3 adsorption·NH3 adsorption–desorption experiments of composite adsorbents were performed on the fixed bed. The results showed that the optimal loading of graphite on CuCl2 was 20 wt% and the optimal adsorption temperature was 25 ℃. The optimal adsorption of CuCl2-G (20) was 0.64 g NH3/g adsorbent. Moreover, the composite adsorbents showed good stability in NH3 adsorption properties during long-term cycling. The cumulative NH3 adsorption capacity of CuCl2-G (20) in the 10 cycles was up to 5.8 g NH3/g adsorbent, which was 0.07 g NH3/g adsorbent higher than that of CuCl2. Notably, all graphite-loaded composite adsorbents showed a stronger NH3 adsorption capacity than a single CuCl2 in the 2nd and subsequent cycles. Thus, CuCl2-G (20) is a promising adsorbent with potential application in the removal and enrichment of excess NH3 produced in industrial processes.

Rate capability and Ragone plots for designing battery thermal management system based on phase change material

Phase change material (PCM), as a passive thermal regulation technology, is anticipated to mitigate the thermal challenges associated with anomalous temperature in lithium-ion batteries (LIBs). Nevertheless, the examination of its performance, i.e., energy and power density, has received limited attention in applications of battery thermal management system (BTMS). The primary aim of this work is to concentrate on the parametric optimization and performance assessment of BTMS utilizing PCM. Initially, a numerical model integrated paraffin/expanded composite and pouch battery is built and validated. Subsequently, a series of parametric studies are conducted to explore several aspects, including PCM type, expanded graphite loading, packing density, and PCM thickness. The thermal rate capability and Ragone plots are used to describe the specific energy and specific power of PCM. Based on that, the effects of PCM properties, geometry, and operating conditions can be effectively clarified. Furthermore, a multi-attribute decision making (MADM) method is introduced to aid variable selection. From analysis, the composite with PCM type of RT28, expanded graphite loading of 1–5 wt%, packing density of 700 kg m−3, and thickness of 3 mm is regarded as a suitable choice to achieve good performance. The present framework is helpful to provide guidance for PCM-based BTMS design.

Fabrication, characterization, and mechanical properties and wear characteristics of graphite nanoplatelets incorporated nanotwinned Cu composites

The present research is focused on the study of microstructural evolution and mechanical behaviour of graphite nanoplatelet (xGnP, where x = multiple layers of graphene) (a graphene isotope) incorporated Cu composites. The limited excellence of Cu in the mechanical field is enhanced by the incorporation of xGnP nanoreinforcement. A dispersion extent of nanoplatelets over the matrix via ultrasonication is reported. The ex-situ fabrication is carried out through powder metallurgy followed by particle fusion via furnace sintering and spark plasma (SP) sintering. Results of characterization showed the homogeneous distribution of graphite nanoplatelet throughout the Cu matrix at lower graphite nanoplatelet loading concentrations. It is also recognized that both furnace sintered and SP sintered Cu composites showed a remarkable enhancement in mechanical properties and wear behaviour with respect to that of similarly fabricated monolithic pure Cu samples. Cu twins are evident in the optical micrographs. The higher incorporation concentration of the graphite nanoplatelet limits the optimum values thus resulting in the non-uniform distribution of the graphite nanoplatelet, formation of relatively bigger conglomerates, and generation of pores. This in turn limited the mechanical performance at higher graphite nanoplatelet loading concentrations due to uneven hardness, poor densification, formation of cracks, and bigger delamination on the surface during the wear of the samples.

Effect of graphite on flax/E-glass/epoxy hybrid polymer composites for its tensile properties: Hybrid polymer composites

In their quest to develop lightweight biodegradable materials for automobile applications, researchers have been pushed to go from synthetic to natural fibres to a large extent. As a result, an experimental study is conducted to assess the implications of stacking configuration, secondary reinforcement and graphite loading on the mechanical properties of hybrid composites (i.e., e-glass/flax/graphite epoxy composite). Different laminates of various loadings of graphite particles are fabricated by hand layup vacuum bagging method of four plies, one group of composites are fabricated by flax fiber as skin layer, E-Glass fiber as core layer and other group of composites are vice versa. The obtained specimens are subjected to a tensile test as per the ASTM standards. The interval plots, probability plots, pareto charts are plotted using Minitab statistical tool to understand the effect of graphite along with the interaction of other parameters. Regression analysis is carried out to develop an empirical equation with a 95% confidence limit for all intervals which fits linearly. According to the findings, the characteristics of hybrid polymer composites are slightly improved with the addition of graphite particulate as one of the reinforcements from 3 wt% to 9 wt% for tensile strength. When comes to stacking sequence, E-Glass utilized as skin layer and treated flax employed as the core layer, showing improved tensile strength of 187.45 MPa. Then the laminates with Flax/E-Glass/Graphite reinforced epoxy composites are serving good enough for medium load structural applications, hence hybridization is recommended.

Effects of tensile and compressive stresses on damage evolution law of nuclear graphite

Nuclear graphite, a quasi-brittle material containing microdefects, is essential for constructing the neutron moderators, reflectors, and cores in very-high-temperature gas-cooled reactors. Such reactors are prone to damage during loading, resulting in the failure of nuclear graphite materials or structures and possibly affecting the integrity of the entire core structure. Therefore, the damage evolution law of nuclear graphite should be studied while assessing the safety of the core. In addition, considering the different mechanical characteristics of quasi-brittle materials under tensile and compressive stresses as well as the complex stress states of quasi-brittle nuclear graphite structures in the core, the effects of stress states on the damage evolution law of nuclear graphite should be unveiled. These aspects are difficult to evaluate owing to the complexity of damage characterisation and measurement throughout the test loading of nuclear graphite under different stress states. Therefore, we propose damage measurement tests of nuclear graphite under unidirectional tensile and compressive stress states based on digital image correlation to obtain damage evolution laws under different stress states. By analysing the effects of different stress states on the damage evolution laws of nuclear graphite, we found that the damage properties under unidirectional tensile and compressive stresses show variations and that damage more likely occurs under tensile stress.

Fully Printed pH Sensor based on Polyaniline/Graphite Nanocomposites

Recently, there is an exceptional growth in research related to the development of flexible sensors for health analysis. pH measurements can be done non-invasively and continuously, making it an excellent parameter for monitoring different stages of wound healing. Here, we report pH functionality of a polyaniline/graphite (PANI/G) composite in a fully-printed potentiometric pH sensor and the effect of graphite loading on sensor functionality. PANI/G composites in different ratios were aerosol-jet printed on Ag/AgCl with and without a graphite layer as the working electrode in a two-electrode potentiometric sensor on a flexible substrate. The role of graphite layer on working electrode in functionality of the sensor has been investigated. The PANI/G composites were prepared by a solution processing method using a graphite paste and polyaniline emeraldine salt powder. Samples were characterized by XRD, SEM, and FTIR analysis to investigate the relations between the physical and chemical relations and the performance of the sensors. The sensors were tested in the pH range from 3 to 10, exhibiting a linear, stable and near-Nernstian sensitivity of 53 mV pH−1 and a response time of 15 s.

Emerging dual carbon fiber batteries

Dual graphite battery emerges as a promising renewable energy storage system with merits of a high working voltage, low cost and environment-friendliness. However, energy density is limited because of a low packing density of graphite. We propose for the first time dual carbon fiber batteries (DCFBs) in which carbon fiber functions as both cathode and anode. With a graphite mass loading of ∼30 mg cm−2 at pitch-based carbon fiber (PCF) cloth, the reversible discharge capacity of PCF-PCF type DCFBs (with PCF cloth cathodes/anodes) can reach 72 mAh g−1 at 0.1 C (1 C corresponding to 80 mAh g−1), resulting in an unprecedentedly high areal capacity of ∼2.2 mAh cm−2. Unlike the general applicability of commercialized carbon fiber as DCFBs anode, only PCF out of five kinds of commercialized carbon fibers can function as DCFBs cathode. Meanwhile, PCF-PCF type DCFB enables investigation into distinct electrochemical behaviors of Li+/PF6−intercalation/deintercalation in PCF. Morphological difference of PCF brought about by Li+/PF6− ions, as found out by ex-situ X-ray diffraction (XRD) and ex-situ scanning electronic microscopy/energy dispersive spectroscopy (SEM/EDS) characterizations, facilitates comprehensive understanding of electrochemical behavior of graphite. This work lays good foundations for future exploration into a new arena of dual ion batteries.

Polyvinylidene fluoride‐poly(vinyl acetate)‐natural graphite blend nanocomposites: Investigations of electroactive phase formation, electrical, thermal, and wetting properties

AbstractSolution blended polyvinylidene fluoride (PVDF)‐20 wt% poly(vinyl acetate) (PVAc)‐natural graphite (NtGr) blend nanocomposites exhibit a very low electrical percolation threshold of less than 0.5 wt% NtGr due to the formation of graphite nanosheets. The electroactive gamma phase induced with and without NtGr in PVDF‐20 wt% PVAc blend film is confirmed by X‐ray diffraction, fourier transform infrared spectroscopy, and differential scanning calorimetry analyzes. The onset degradation temperature corresponding to PVDF in PVDF‐20 wt% PVAc blend nanocomposites is increased by 27°C when 1 wt% NtGr is incorporated into the blend, suggesting enhanced thermal stability of blend nanocomposites. Due to an increase in surface roughness of PVDF‐20 wt% PVAc‐3 wt% NtGr as evidence by field emission scanning electron microscopy analysis, the water contact angle increases to 141.6° from 83.44° for PVDF‐20 wt% PVAc blend. AC conductivity analysis suggests hopping conduction in PVDF‐20 wt% PVAc‐x wt% NtGr (x = 1, 3, 5) blend nanocomposites. The interjunction capacitance increases with graphite loading in the blend.

Experimental investigations on effect of graphite loading on melt flow behaviour of ABS-Gr composite for fused filament fabrication (FFF) process

ABSTRACT In FFF process, the melt flow rate (MFR) of the polymer matrix composite material is an important factor in selecting the appropriate process parameters for printing parts. Concerning FFF, MFR and the extrusion temperature (ET) are important parameters due to their influence on the degree of layer adhesion and strength. The current study aims to investigate the MFR of ABS composite by varying the proportion of graphite (Gr) powder. The effects of Gr loading (5, 10, and 20 wt%) on MFR of composite and suitability for FFF process were investigated using MFI machine under different extrusion temperatures and extrusion loads. ANOVA and S/N ratio analysis were used to determine the significance of each process parameter and percentage of error involved in experiments. The experiments were performed three times at set of levels to find optimum response and reduces the error. The results shows that ETmost influential parameter among others, error was less than 1% in the experimental study. A signal-to-noise (S/N) ratio analysis is performed to optimise process parameters, with ‘larger is the better’ criterion. The combination ET3-EL3-FL1 i.e. ET 240°C, EL 5 kg and FL 5 wt% is observed as optimal process parameters values to get optimal MFR.

Latent heat of molten salt transport across graphite induced anisotropic interface

The supported phase change of molten salt is a promising approach for thermal energy storage. Here we reveal a diffusion-controlled latent heat transportation by a controllable graphite induced anisotropic interface. It focus on salt crystallization processes across the interfaces during phase changing, and underling relationship between interfacial anisotropy and latent heat transport was understood: The anisotropic interface induced by graphite tends to compete with the driving force of crystallization in confinement, releasing the transport limitation for the latent heat. The sharp density gap with a large loading of graphite could not contribute to release the transport limitation but serves as a layer for driving the crystallization, leading to the failure of graphite anisotropic interface for diffusion control over latent heat. This work considered is the microscopic kinetics of salt crystallization and latent heat transfer in confinement, so clarification of the interdependences has far-reaching implications for understanding material design strategies.

The Effect of Graphite Loading as Reinforcement on Carbon Foam from Natural Resources

This study is to determine the effect of graphite as reinforcement material on natural resources carbon foam on the mechanical and physical properties. Sucrose is used as carbon precursor and graphite with various concentration from 0 wt% to 0.3 wt% was added into the carbon foam. Carbon foam was prepared by using template method followed by pre curing and carbonization process. Pre curing process was take place at 250°C and carbonization process was carried out at 900°C under inert atmosphere. The morphology, porosity, density and compressive strength were characterised in this experiment. Through Scanning Electron Microscope (SEM), graphite can be seen clearly embedded into the ‘window’ and fill the void space. Porosity of carbon foam decrease when the concentration of graphite increase and the density of carbon foam increase when the concentration of graphite increase. Carbon foam with 0.3 wt% graphite added shows the highest compressive strength (1.84 N/mm2) compared with carbon foam without graphite added (0.95 N/mm2). The properties of carbon foam are significantly influenced by the addition of graphite loading.

Production of aromatic hydrocarbons from microwave-assisted pyrolysis of municipal solid waste (MSW)

The microwave-assisted conversion of municipal solid waste (MSW) into value-added products would be a promising option to tackle MSW piles. The present work was intended to understand the effect of microwave power (300, 450, and 600 W) and graphite susceptor loading (10, 30, and 50 g) on MSW valorization. Response surface methodology was used to analyze the impact of input variables on product yields and energy consumption. The heating rate increased, and microwave energy consumption decreased with the increase in microwave power. An increase in susceptor quantity resulted in a reduction in heating rates and also energy consumption. Nearly 84–88 wt% of MSW was converted into gases (42–60%), oil (26–42%), and char (12–16%) products. The carbon number distribution of oil fraction is in the range of C5 to C20 with a high yield of carbon content (74–91%). A high yield of aromatic hydrocarbons (84.5%) was obtained at 600 W microwave power and 30 g of the susceptor. The char fraction is rich in carbon content (80–90%) with a reasonable pore area (111–152 m2/g). This work demonstrated the feasibility of MSW upgradation into value-added chemicals, materials, and energy-rich fuel products.

Manipulating the self-assembly behavior of graphene nanosheets via adenine-functionalized biodegradable polymers

Electrically conductive supramolecular polymer composites, based on a combination of natural graphite and the adenine-functionalized biodegradable oligomer 3A-PCL, are able to directly exfoliate crystalline graphite into highly disordered graphene nanosheets with well-tailored structural and physical properties. Herein, we discover 3A-PCL can self-assemble into well-ordered lamellar nanostructures on the surface of graphite due to the strong affinity between 3A-PCL and graphite, and thus lead to direct exfoliation of graphite into well-suspended graphene nanosheets in an organic solvent. Furthermore, after drying, the resulting graphite/3A-PCL composites exhibit stable thermoreversible phase transition behavior between viscous and elastic states, and the number of graphene layers exfoliated can be controlled by tuning the content of 3A-PCL within the composites. Importantly, these newly developed graphene composites possess a low electrical resistivity of 1.5 ± 0.7 mΩ·cm at a graphite loading of 23 wt%, which is more than an order of magnitude lower than that of pristine graphite. Given the simplicity of the production process, well-tailored physical properties and excellent conductive performance, this development offers a highly efficient process for the fabrication of multifunctional supramolecular graphene nanosheets that holds great potential for conductive device applications.