Amount Of Carboxymethyl Cellulose Research Articles

Preparation of fully physically crosslinked double-network gel and its fire prevention mechanism

It is important to gain an in-depth understanding of the structure of fire prevention and extinguishing materials during self-heating of coal. In this paper, an Al3+-CMC/PAM-MMT fire prevention and extinguishing gel with double-network was prepared using sodium carboxymethyl cellulose (CMC) and polyacrylamide (PAM) as raw materials, and aluminum citrate (AlCit) and sodium montmorillonite (Na-MMT) as auxiliary materials, by introducing the fully physically crosslinking effect. The optimal amounts of CMC, PAM, AlCit and MMT were determined to be 2 %, 3 %, 8 %, and 3 %, respectively, based on gelation time, stability, and resistance of the gel. The micromorphological image of the double-network gel exhibited a laminar structure of parallel-aligned fibrous networks, where the pores and channels exhibited more complex shapes and became smaller in size, highlighting the superiority of the double-network architecture. The rheological tests showed that the double-network gel had superior structural stability and viscosity under varying shear rates, making it more effective in covering the fire source, enhancing extinguishing efficiency. Additionally, its higher storage and loss moduli indicated stronger elasticity and mechanical properties compared to the single-network gel, emphasizing its advantages in energy storage and recovery. The characterization of active functional groups showed that there was an effective suppression of reactions involving hydroxyl, hydrocarbon, and carbonyl functional groups, during the spontaneous combustion process of coal, following treatment with the gel. Additionally, a proposed mechanism for the gel formation was presented. In the sealing performance test, the pressure-bearing capacity of the double-network gel was approximately twice that of the single-network gel. It indicated that the multi-level structure formed by the gel led to higher density of physical cross-linking points, which provided better sealing performance. Thermogravimetric analysis showed significant decrease in total calorific value and increase in activation energy of coal, after treatment with the gel, rendering it more difficult for spontaneous coal combustion. In the small-scale fire extinguishing performance test, the double network of Al3+-CMC/PAM-MMT gel demonstrated effective suppression of spontaneous combustion of coal and reduced the susceptibility to re-ignition. The fire prevention mechanism of the gel was further explored experimentally.

The Production of Coating Film with Sweet Potato Starch and Carboxymethylcellulose from Water Hyacinth on Storage Life Extension of Mango (Mangifera indica L.)

The objective of this research was to study the production of coating films with sweet potato starch (SPS) and carboxymethyl cellulose (CMC) from water hyacinth and to study the effect of the coating on the storage life extension of mangoes. The coating film was prepared by dissolving sweet potato starch in water at a concentration of 5 % w/v and adding CMC from water hyacinth at 5 different concentrations: 0, 5, 10, 15, and 20 % based on the weight of the starch. Glycerol was added as a plasticizer at 20 % of the weight of the starch solution. The mixture was then dried at 65 °C for 18 h. The study found that the thickness of the film decreased with higher concentrations of CMC from water hyacinth. The water activity (aw) ranged from 0.35 to 0.42, and the solubility and water vapor permeability of the film decreased with increasing CMC concentration. In the degradation study, it was observed that the films could biodegrade from 42 to 100 % for 8 weeks, with degradation rates decreasing as the amount of CMC from water hyacinth increased. Coating Mango with 10 % w/w CMC helped delay weight loss, skin color changes, and extended the shelf life of mango for up to 18 days at room temperature (28 ± 2 °C, 65 ± 2 % RH), compared to the control group with a shelf life of 12 days. These results indicate that films made from SPS/CMC from water hyacinth, with glycerol as the plasticizer, can effectively be used for preserving fruits and creating biodegradable films. HIGHLIGHTS The coating film of sweet potato starch (SPS) and Carboxymethylcellulose (CMC) from Water Hyacinth was prepared The effect of adding different CMC concentrations in SPS films was investigated This coating film is cost-effective and biodegradable The coating film of SPS and CMC from water hyacinth enhances the shelf-life of perishable fruit GRAPHICAL ABSTRACT

Synthesis of Hydrogel Based on Poly (Acrylic Acid–Co‐Vinyl Acetate) Grafted on Modified Recycled Cellulose for Use in Fertilizer Slow‐Release System

The aim of this work is a synthesis of suitable hydrogel to produce slow‐release fertilizer using recycled cellulose which is obtained from waste paper. For this purpose, initially, we extracted alpha cellulose from waste paper and modified it to obtain carboxymethyl cellulose (CMC). Then, the CMC was converted to a suitable hydrogel through in situ graft copolymerization of acrylic acid and vinyl acetate in the presence of methylene bisacrylamide as a crosslinker. The various factors that affect hydrogel synthesis, such as the amounts of CMC, monomers, initiator, and crosslinker, were evaluated. In the optimized formulation, the weight ratio of monomers to CMC is 7, the molar ratio of monomers to each other is 1, and the crosslinker is used as 3 molar percent of monomers. The products were characterized using Fourier transform infrared, thermal gravimetric analysis, and scanning electron microscope analyses. The swelling behavior of the synthesized hydrogels was evaluated in different environments, such as distilled water, tap water, salt water, and different pH levels. The swelling ratio increases with an increase in pH level. Between the synthesized hydrogels, the best one was selected for slow‐release fertilizer production and loaded with 20‐20‐20 fertilizer (NPK), and the release behavior was evaluated. In an alkaline pH, there was a long time for NPK release within a slow‐release medium and even after 361 h, the release process was continued. Also, the performance of the fertilizer‐loaded hydrogel in soil using water holding capacity and water retention ratio tests were evaluated.

Optimization of carboxymethyl cellulose-gum Arab-based hydrogel beads for anticancer drugs delivery

Response surface methodology was successfully utilized to optimize the amounts of carboxymethyl cellulose (CMC) and gum Arab (GA) to fabricate hydrogel beads for the delivery of anticancer drugs. Drug encapsulation efficiency process (%DEE) and cumulative release (%R8h) of hydrogel beads were investigated with different amounts of CMC and GA with Fe (III) cross-linker. The numerical validation resulted in an optimized nanocomposite of CMC (99.61 mg) and GA (77.84 mg) with a DEE of 55.70 ± 2.15 % and R8h of 44.78 ± 0.27 %. The characterization approaches indicated the successful formation of this nanocomposite. The swelling behavior of the beads was triggered by pH change, and the drug release profile showed prolonged sustainable release that followed the Higuchi model with a non-Fickian mechanism. This nanocomposite could be a promising nanocarrier for drug loading and its controlled delivery.

Multi-characteristic tannic acid-reinforced polyacrylamide/sodium carboxymethyl cellulose ionic hydrogel strain sensor for human-machine interaction

Big data and cloud computing are propelling research in human-computer interface within academia. However, the potential of wearable human-machine interaction (HMI) devices utilizing multiperformance ionic hydrogels remains largely unexplored. Here, we present a motion recognition-based HMI system that enhances movement training. We engineered dual-network PAM/CMC/TA (PCT) hydrogels by reinforcing polyacrylamide (PAM) and sodium carboxymethyl cellulose (CMC) polymers with tannic acid (TA). These hydrogels possess exceptional transparency, adhesion, and remodelling features. By combining an elastic PAM backbone with tunable amounts of CMC and TA, the PCT hydrogels achieve optimal electromechanical performance. As strain sensors, they demonstrate higher sensitivity (GF = 4.03), low detection limit (0.5 %), and good linearity (0.997). Furthermore, we developed a highly accurate (97.85 %) motion recognition system using machine learning and hydrogel-based wearable sensors. This system enables contactless real-time training monitoring and wireless control of trolley operations. Our research underscores the effectiveness of PCT hydrogels for real-time HMI, thus advancing next-generation HMI systems.

Stability properties of slurry based on coal-to-liquid gasification ash slag

ABSTRACT The coal-to-liquid gasification ash and slag (GAS) is a solid waste with high yield, difficult degradation and environmental hazards. In this study, a novel extinguishing grouting material was made in the light of GAS, and carboxymethyl cellulose (CMC) was introduced as a dispersant for GAS slurry for easy blockage and bursting of pipes during the transportation of grouting material. Zeta-potential measurement, X-ray fluorescence and water separation experiment were utilized to discuss the mechanism and suspension stability of GAS slurry with different water-cement ratios and amount of CMC addition. The fire extinguishing material and the optimal mixing ratios were also obtained. The content of SiO2, Fe2O3, CaO and Al2O3 in GAS accounted for more than 80% of the total composition, and the main substances were gypsum, quartz and calcite. CMC had a prominent improvement effect on the suspension stability of slurry, and the more the added dosage, the stronger the suspension stability. The slurry suspension stability was maintained by steric hindrance and electrostatic repulsion; when the water-cement ratios were 1: 0.8, 1: 1.0 and 1:1.4, the optimal addition amounts of CMC were 1.5%, 1.25% and 0.75%, respectively.

Effects of sodium carboxymethyl cellulose and poly (acrylic acid) on the agglomeration behavior of aqueous silicon suspensions

We investigate the effects of carboxymethyl cellulose (CMC) and poly (acrylic acid) (PAA) on the dispersion state of silicon particles and the mechanism thereof. Here, we report severe agglomeration of silicon particles induced by the hydrophobic interaction arising from CMC(degree of substitution; DS 0.7). Although the adsorption amount of CMC (DS 0.7) onto the silicon surface is comparable to that of PAA, its effect on particle dispersion is significantly different. The agglomeration mechanism is systematically explored in terms of polymer-polymer and particle-polymer interactions by varying the DS of CMC and the pH of the suspensions. We demonstrate that the attraction between polymers adsorbed on the silicon surface and the affinity between the particle and polymer determine the degree of silicon agglomeration. The hydrophobic attraction of CMC(DS 0.7) promotes silicon agglomeration significantly, whereas CMC(DS 1.2) deficient in attraction disperses silicon particles well. Silicon particles weakly agglomerate in Si/PAA suspensions due to hydrogen bonding between PAA chains and due to the high affinity between PAA and the silicon surface. The dispersion of Si/CMC(DS 0.7 or 1.2)/PAA suspensions is primarily dominated by PAA through its high affinity with silicon and corresponding favorable adsorption on the silicon surface. This is the first attempt to quantitatively assess and compare the impact of CMC and PAA on the agglomeration behavior of silicon particles and reveal the underlying mechanism. This paper provides a fundamental understanding to control the dispersion homogeneity and stability of silicon-containing electrodes.

Temperature-responsive hydrogel prepared from carboxymethyl cellulose-stabilized N-vinylcaprolactam with potential for fertilizer delivery

The growth of plants is highly dependent on sufficient water and suitable fertilizer nutrients, but the soil often loses moisture and the fertilizers are low efficiency. To address this issue, the temperature-responsive hydrogels were developed using the N-vinylcaprolactam (NVCL) dispersed in water through the emulsification of carboxymethyl cellulose (CMC) and acrylamide (AM), and urea was loaded into the hydrogel as a fertilizer. The amount of CMC and monomer have an effect on the structure, mechanical properties, swelling ability, and temperature sensitivity of the hydrogel. Therefore, the maximum swelling ratio of the hydrogel can reach 2056 % with the increasing hydrophilic groups, and the hydrogel exhibits a deswelling behavior as the temperature rises to higher than LCST due to the temperature responsiveness. Moreover, the fertilizer can rapidly release when the temperature is higher than LSCT, and exhibits similar release behavior in water and soil. Thus, the temperature-responsive hydrogel shows a great potential application for the controlled release of water and fertilizer in agriculture and forestry.

Delivery of curcumin in a carboxymethyl cellulose and hydroxypropyl methyl cellulose carrier: Physicochemical properties and biological activity

Curcumin solid dispersions (Cur SDs) were prepared using hydroxypropyl methyl cellulose (HPMC) and sodium carboxymethyl cellulose (CMC) at different dosages. The results of Fourier transform infrared spectroscopy and Raman spectroscopy showed that the characteristic peak of curcumin shifted, and the addition of CMC enhanced this phenomenon. The addition of CMC reduced the contact angle, increased the surface free energy, and improved the solubility of Cur SDs. These changes were positively correlated with the amount of CMC. The surface morphology of Cur SDs changed from needle-like to sheet-like as observed by scanning electron microscopy. Cur SDs prepared by CMC and HPMC retained good biological activity. HT-29 human colon cancer cell analysis showed that the addition of CMC significantly improved the anti-proliferation effect of Cur SDs, thus enhancing the bioavailability of curcumin. Solid dispersions made with CMC and HPMC will be a promising hydrocolloid carrier to improve oral bioavailability and efficacy of curcumin.

Effect of carboxymethyl cellulose (CMC) on some physico-chemical and mechanical properties of unrinsed surimi gels

The objective of this study was to evaluate the effect of the carboxymethyl cellulose (CMC) on the physico-chemical and mechanical properties of unrinsed surimi gels during heat treatment. The results revealed that the addition of CMC could significantly (p < 0.05) improve the gel strength, texture properties of unrinsed surimi gels and imparted better color perception compared with the control group showing lower gel strength and poorer water-holding capacity. The addition of 0.5 and 1.5 g/100 g CMC also promoted the formation of a more uniform and compact gel network structure of the unrinsed surimi gels, locking more water in the gel network, significantly improved the water holding capacity of the gels and enhancing their viscoelastic properties (p < 0.05). In conclusion, an appropriate amount of CMC can be added to unrinsed surimi as a food additive, and 1.5 g/100 g was the optimal addition amount obtained in this study, which provides important information for improved the gel properties of unrinsed surimi.

Influence of carboxy methyl cellulose (CMC) colloid on irrigation frequency of planting material with a closed root system

This article discusses the impact of different amounts of carboxymethyl cellulose (CMC) colloid on the frequency of watering seedlings with a closed root system in containers. The study found that increasing the CMC dose from 0.05% to 2.0% of the dry soil mass resulted in a decrease in the number of irrigations per month during summer from 5-6 to 2-3, an increase in the frequency from 5-6 to 11-16 days, and a reduction in the volume of irrigation water per container from 3700 cm3 to 2250 cm3 during the growing season. However, it should be noted that doses higher than 0.4% resulted in the formation of a thick soil crust in the containers, which negatively affected seed germination and plant growth.

Investigation into a conductive artificial muscle based on sodium alginate/cellulose with good response characteristics

Artificial muscle is a research topic that combines new driving methods, intelligent materials and bionics. To overcome the weaknesses of the electric actuator made of bio-gel materials, e.g. poor driving effect and short working life, the working mechanism of artificial muscle based on sodium alginate/cellulose (SCAM) and how to improve its performance have explored in this study. First of all, the basic process of preparing conductive artificial muscle with sodium alginate and carboxymethyl cellulose (CMC) as the main materials were defined. Secondly, the addition amount of CMC was optimized based on parameters such as the single-cycle output force, working life and curvature. Thirdly, the electrochemical and microscopic testing methods were applied to expound the internal reaction mechanism of improving the response characteristics of samples based on the FITR. The results show that the addition of CMC enables SCAM to have better response characteristics in the electric field, which is applicable to the practical application of flexible machinery and bio-gel artificial muscle.

Effects of Zeolites and Carboxymethyl Cellulose Molecular Weights on the Quality of Coating Color and Inkjet Paper

The study aim was to develop a technology that can improve the quality of inkjet paper while reducing the production cost. Silica has so far been the most promising and suitable pigment for inkjet paper. However silica has limitations such as high price, high viscosity and flow characteristics that prevent high-speed drying. A previous study reported that zeolites can partially replace silica to produce inkjet paper. The drawback of replacing silica with zelolites is that the viscosity of the coating color is lowered, which generates other issues in the coating color and manufacture of inkjet paper. For this reason, carboxymethyl cellulose (CMC) was used as a thickener to control the coating color viscosity. the effect of molecular weight and addition amount of CMC added to the coating color using zeolites on the rheological behavior of the coating color with zeolite. Addition of CMC improved the viscosity and flow characteristics of the coating color. Additionally, the physical properties excluding optical properties, and smoothness of the manufactured inkjet paper were improved.

Investigation of Polycaprolactone/Carboxymethyl Cellulose Scaffolds by Mechanical and Thermal Analysis

The objective of this work was to learn more about three-dimensional porous scaffolds made from biomaterial based on polycaprolactone (PCL) containing different amounts of carboxymethyl cellulose (CMC) nanoparticles. Composite material samples containing 0, 2, 6.5, 11, 15.5, and 20% w/w of CMC and PCL/CMC scaffolds were prepared with the use of the salt particle leached technique. The mechanical properties were evaluated with the compressive strength analysis method. The studied temperature range started at very low temperatures and ended at crosslinking temperatures. It was evaluated using the thermal analysis methods of Differential Scanning Calorimetry (DSC) in the range 0ºC-200ºC. The results revealed that the compressive modulus of blended PCL/CMC scaffold was higher than the one of pure PCL scaffold (582.2±106.2 kPa for pure PCL scaffold and 612.2±296 kPa for blended scaffold which contained 20% of CMC). For DSC analysis, in addition to the 15.5% w/w CMC PCL/CMC composite scaffold, other proportions of composite materials showed a decrease in crystallization temperature. The crystallinity of PCL-20% CMC was higher than that of PCL scaffolds.

Dual-functional porous and cisplatin-loaded polymethylmethacrylate cement for reconstruction of load-bearing bone defect kills bone tumor cells

Malignant bone tumors are usually treated by resection of tumor tissue followed by filling of the bone defect with bone graft substitutes. Polymethylmethacrylate (PMMA) cement is the most commonly used bone substitute in clinical orthopedics in view of its reliability. However, the dense nature of PMMA renders this biomaterial unsuitable for local delivery of chemotherapeutic drugs to limit the recurrence of bone tumors. Here, we introduce porosity into PMMA cement by adding carboxymethylcellulose (CMC) to facilitate such local delivery of chemotherapeutic drugs, while retaining sufficient mechanical properties for bone reconstruction in load-bearing sites. Our results show that the mechanical strength of PMMA-based cements gradually decreases with increasing CMC content. Upon incorporation of ≥3% CMC, the PMMA-based cements released up to 18% of the loaded cisplatin, in contrast to cements containing lower amounts of CMC which only released less than 2% of the cisplatin over 28 days. This release of cisplatin efficiently killed osteosarcoma cells in vitro and the fraction of dead cells increased to 91.3% at day 7, which confirms the retained chemotherapeutic activity of released cisplatin from these PMMA-based cements. Additionally, tibias filled with PMMA-based cements containing up to 3% of CMC exhibit comparable compressive strengths as compared to intact tibias. In conclusion, we demonstrate that PMMA cements can be rendered therapeutically active by introducing porosity using CMC to allow for release of cisplatin without compromising mechanical properties beyond critical levels. As such, these data suggest that our dual-functional PMMA-based cements represent a viable treatment option for filling bone defects after bone tumor resection in load-bearing sites.

Experimental Investigation of Heat Transfer with Natural Convection of Non-Newtonian Fluid Inside the Enclosure with Hot Obstacle

In this study, heat transfer utilizing non-Newtonian fluids with a power-law model in a rectangular enclosure containing a hot obstacle was verified experimentally. The impact of aspect proportion (AR) on fluid flow characteristics and heat transfer, obstacle shapes, and various amounts of carboxymethylcellulose was explored with distilled water which in turn controls the index of powers-law (n). The findings show that the increases in the Number of Rayleigh, lead to the greater the Number of Nusselt, and the greater the non-Newtonian behavior, increased the heat transfer. There is also a noticeable impact when changing the shape of an obstacle on heat transfer as the cylindrical shape enhances heat transfer greater than the cuboid shape. As for aspect proportion, it also affects heat transfer inversely.

Biodegradable film of black mulberry pulp pectin/chlorophyll of black mulberry leaf encapsulated with carboxymethylcellulose/silica nanoparticles: Investigation of physicochemical and antimicrobial properties

In this study, pectin was extracted from black mulberry fruit pulp and chlorophyll was extracted from black mulberry leaves. The extracted chlorophyll was encapsulated with carboxymethylcellulose (CMC). Black mulberry pectin/chlorophyll of black mulberry leaf encapsulated with carboxymethylcellulose/silica nanoparticles was prepared (Pec/Ch-CMC/SiO2). The physicochemical, mechanical and antimicrobial properties of the prepared films were investigated. SEM, FTIR, TGA and XRD techniques were used to study the structure of the films. According to the results, silica increased the thickness and decreased the moisture and solubility of the films. Increasing the amount of CMC in the capsules used in the film increased the thickness, moisture and solubility of the films. Silica increased the tensile strength of the film and reduced the flexibility of the film, while CMC reduced the tensile strength and increased the flexibility of the film. Chlorophyll and silica greatly increased the antioxidant properties of the film. Encapsulated chlorophyll and silica increased the antibacterial properties of the film against Escherichia coli and Staphylococcus aureus. SEM images showed that by simultaneously adding encapsulated chlorophyll and silica to the pectin structure, almost all gaps in the pectin surface were filled. According to the FTIR spectra, electrostatic interactions between pectin polymer chains with encapsulated chlorophyll and silica were confirmed. According to TGA results, the simultaneous addition of encapsulated chlorophyll and silica to the film increases the thermal stability of the film. According to the results, the pure pectin film has a semi-crystalline structure that the addition of silica and encapsulated reduces its crystalline structure.

Quality of Emulsions Containing Fat Blends Modified by Enzymatic Catalysis

The purpose of this study was to evaluate the effect of the enzymatic modification of muton tallow and hemp seed oil fat blends. An attempt of application of these fat blends as fat phases in emulsion systems with various amount of carboxymethylcellulose was made. Fat blends before and after enzymatic catalysis were assessed in the context of polar and non-polar fractions content, antioxidant activity, oxidative stability and texture. Emulsions were investigated in the terms of their stability, color, microstructure, droplets diameter, and viscosity. The study revealed that emulsions containing as a fat phases modified blends with greater share of mutton tallow showed more favorable properties, and greater stability. The presented emulsions are a model dispersion system, after adjustment of the additives they could be used as chemical, food or cosmetic products.

Fabrication of Bioplastic from Rice Straw

&lt;p&gt;&lt;strong&gt;Abstract.&lt;/strong&gt; Oil based plastics have been proven as severe pollutants for the environments as they required years to be degraded. Thus, bioplastics are very attractive as the solution of this problem as they easier to be degraded in soil. This work was aimed to fabricate bioplastics from rice straw, with addition of carboxymethyl cellulose (CMC) and glycerol. Prior to the bioplastic fabrication, cellulose was extracted from rice straw through digestion process using ethanol solution (50% w/w) and sodium hydroxide solution (8% w/w) as catalyst. Digestion process was held for 60 minutes at temperature of 120 &lt;sup&gt;o&lt;/sup&gt;C. Bioplastics were produced by blending dried pulp, carboxymethyl cellulose, and glycerol. Five grams of dried cellulose was dissolved in 100 ml of water. The amount of CMC and glycerol added to the pulp solution were varied from 1 ml to 2 ml and 0.5 to 1.5 grams, respectively. Swelling test (both in water and oil) and biodegradability test were conducted to study the performance of the bioplastics. Results showed that bioplactic dissolved easily in water. During oil swelling test, it showed that higher glycerol content increases the oil proof characteristic of the bioplastic. Meanwhile, the CMC content has no impact during the oil swelling test. The best composition of the bioplastic was achieved with the CMC and glycerol contents of 1.382% (w/w) and 1,843% (w/w), respectively, with the lowest oil swelling test result of 55%. Biodegradability of the bioplactics were lower in higher CMC and glycerol contents. The best composition with maximum weight reduction of the bioplastics was achieved by the bioplastic with 0.469% (w/w) of CMC content and 0.939% (w/w) of glycerol.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords:&lt;/strong&gt; Bioplastic, Rice Straw, CMC, Glycerol, Swelling, Biodegradability&lt;/p&gt;

Effect of NaCl concentration on the dispersion, stability and rheological properties of MWNTs by CMC

A detailed study of the dispersion, rheological and adsorption behaviors between multi-walled carbon nanotubes (MWNTs) and sodium carboxymethylcellulose (CMC) at different NaCl concentration were presented. The experimental results suggested that NaCl concentration governed the dispersion and stability of MWNTs. A small amount of NaCl was contributed to the dispersion and stability of MWNTs, while as the NaCl concentration increased, the MWNTs formed aggregates and the MWNTs suspension became unstable. Adsorption amount, Raman spectroscopy, zeta potential, and adsorption conformation were investigated systematically to elucidate the mechanism of this interesting phenomenon. Surprisingly, results from thermogravimetric analysis (TGA) shown that adsorption amount of CMC on MWNTs didn’t change under any circumstances. The value of zeta potential increased slightly at first and then dropped sharply as the increasing of NaCl concentration. The microstructures were measured by TEM. It was found that uniform CMC adsorption layers were formed on the surface of MWNTs at low NaCl concentrations. However, for the high-salt solution, the MWNTs were wrapped by CMC agglomerates, resulting in poor dispersion stability.