Characteristics Of Microspheres Research Articles

Facile hydrothermal synthesis and characteristics of B-doped TiO2 hybrid hollow microspheres with higher photo-catalytic activity

The boron doped titanium oxide hybrid hollow microspheres were easily prepared by hydrothermal method. The scanning and transmission electron microscopy images demonstrated that the hybrid hollow microspheres possessed smooth outer shell and hollow interior. Their crystal structure, chemical state, amount of surface active groups and spectral response region were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, infrared spectra and UV–Vis diffuse reflection spectra, respectively. Methylene blue aqueous solution served as a target pollutant to evaluate the photo-catalytic activity under simulated sunlight. It turned out a higher photo-catalytic activity of boron doped hybrid hollow microspheres, comparing with the undoped ones.

Silk fibroin microspheres prepared by the water-in-oil emulsion solvent diffusion method for protein delivery

Silk fibroin (SF) microspheres were prepared by the simple water-in-oil emulsion solvent diffusion method without any surfactants. Aqueous SF solution and dichloromethane were used as water and oil phases, respectively. Influence of water: oil phase ratios on SF microsphere characteristics was investigated. From FTIR spectra, the resulting SF microspheres showed predominantly random coil SF conformation. SF microspheres observed from SEM images were spherical with deflated surfaces in some cases. Particle sizes of the SF microspheres were in the range 45–92 μm. Finally, bovine serum albumin (BSA) was used as a model protein for entrapment within the SF microspheres. The BSA-loaded SF microspheres were larger than unloaded SF microspheres. In vitro release tests indicate that BSA release from the SF microspheres was influenced by BSA content.

PEGylated TNF-related apoptosis-inducing ligand (TRAIL)-loaded sustained release PLGA microspheres for enhanced stability and antitumor activity

The purpose of this work was to develop an effective PEGylated TNF-related apoptosis-inducing ligand (PEG-TRAIL) delivery system for antitumor therapy based on local injection to tumor sites that has a sustained effect without protein aggregation or an initial release burst. The authors designed poly (lactic-co-glycolic) acid (PLGA) microspheres that deliver PEG-TRAIL locally and continuously at tumor sites with sustained biological activity and compared its performance with that of TRAIL microspheres. TRAIL or PEG-TRAIL was microencapsulated into PLGA microspheres using a double-emulsion solvent extraction method. Prepared TRAIL and PEG-TRAIL microspheres showed entirely spherical, smooth surfaces. However, PEG-TRAIL microspheres exhibited a 2.07-fold higher encapsulation efficiency than TRAIL microspheres, and exhibited a tri-phasic in vitro release profile with a lower initial burst (15.8%) than TRAIL microspheres (42.7%). Furthermore, released PEG-TRAIL showed a continued ability to induce apoptosis over 14 days. In vivo pharmacokinetic studies also demonstrated that PEG-TRAIL microspheres had a sustained release profile (18 days), and that the steady-state concentration of PEG-TRAIL in rat plasma was reached at day 3 and maintained until day 15; its steady-state concentration in rat plasma changed from 1444.3 ± 338.4 to 2697.7 ± 419.7 pg/ml. However, TRAIL microspheres were released out within 2 days after administration. Finally, in vivo antitumor tests revealed that tumor growths were significantly more inhibited by a single dose of PEG-TRAIL microspheres than TRAIL microspheres when delivered at 300 μg of TRAIL/mouse. Tumors taken from mouse treated with PEG-TRAIL microspheres showed 78.3% tumor suppression at 24 days, and this was 3.02-fold higher than that observed for TRAIL microspheres (25.9% tumor inhibition). Furthermore, these improved pharmaceutical characteristics of PEG-TRAIL microspheres resulted in superior therapeutic effects without detectable side effects. These findings strongly suggest that PEG-TRAIL microspheres offer a new therapeutic strategy for the treatment of cancers.

Effect of Additives on Characteristics of Poly(3-Hydroxybutyrate) Microspheres

Poly(3-hydroxybutyrate) (PHB) based microspheres were prepared via double emulsion solvent evaporation using polyethylene glycol (PEG), poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV), polylactide (PLA), poly(dl-lactic-co-glycolic acid) (PLGA) or chitosan (CTS) as the additive of wall polymers. It was found that additives had distinct effect on the properties of microspheres, such as the yield, drug loading, average diameter, crystallization states microstructure and surface morphological characters. PHB based microspheres using PEG as the additive had the lowest yield, the smallest average diameter, and the highest drug loading which reached 12.2% thereinto. At the same time it had the lowest crystallinity of PHB, and the diameter of the crystal particles was only 11.44 nm. It was feasible to prepare PHB based microspheres using PEG and PHBV as additives, which had relatively high protein loading but different microstructures and surface morphologies, and they were anticipated to have a good effect of controlled release.

Preparation and Fluorescence Characteristics of Amido-Functionalized Dual-Fluorescent Microspheres with Core/Shell Structure

A novel two-step modified seeded polymerization method for the preparation of AFDFMs with a core/shell structure is developed. Their morphology is characterized by means of TEM and SEM, further characteristics are studied using FT-IR, fluorescence microscopy, laser confocal fluorescence microscopy, and fluorescence spectroscopy. TEM and SEM images provide clear proof of a core/shell structure. Fluorescence spectroscopy shows that AFDFMs exhibit tunable fluorescence characteristics with one or two emission wavelengths (515 and 575 nm) depending on the excitation wavelengths. Amido and carboxy groups on the AFDFM shell layer allow the formation of linkages with biomolecules for biological imaging or molecule detection, opening opportunities for biomedical applications.

Anti-Tumor Necrosis Factor-Alpha–Loaded Microspheres as a Prospective Novel Treatment for Crohn's Disease Fistulae

Antibodies to tumor necrosis factor alpha (TNF-α) have been successful in treating perianal fistulae in Crohn's disease, but current modes of delivery are limited. Microspheres are currently being assessed as scaffolds for tissue engineering and drug delivery devices. The aim of this study was to produce anti-TNF-α antibody-encapsulated microspheres using thermally induced phase separation (TIPS) and to characterize their behavior. Anti-TNF-α antibody was encapsulated into the microspheres (100 mg infliximab/g poly[lactide-co-glycolide] w/w) using a novel technique combining a vibration encapsulator unit with a TIPS process, using either lyophilized particulate antibody or an aqueous solution of antibody. Microspheres were incubated in phosphate-buffered saline for collection of supernatant and assessment of degradation. The amount and biological activity of the encapsulated antibody released from the microspheres was assessed by enzyme-linked immunosorbent assay and its ability to neutralize recombinant human (rh)TNF-α in vitro with a cytotoxicity assay. An in vitro wound scratch assay was used to assess the effect of released antibody on fibroblast migration. Ultrastructural characteristics of the different microspheres were characterized by scanning electron microscopy. Highly porous microspheres released anti-TNF-α antibody under zero-order kinetics and inhibited the cytotoxic activity of rhTNF-α, producing a significant increase in cell viability compared with cells treated with rhTNF-α alone. This effect was most pronounced with microspheres fabricated by blending lyophilized particulate anti-TNF-α antibody into the polymer solution, which also significantly reduced the release of lactate dehydrogenase. Anti-TNF-α antibody encapsulated into highly porous microspheres was released in a controlled manner and exhibited biological activity against TNF-α. The technique used to produce TIPS microspheres is rapid and provides high encapsulation efficiency. This technique could also be applied to other therapeutic peptides where rapid fabrication and high yields are required.

Effect of hydrophobic/hydrophilic characteristics of magnetic microspheres on the immobilization of BSA

Core-shell magnetic poly(styrene-acrylamide-acrylic acid) microspheres with carboxyl groups were successfully synthesized via dispersion copolymerization in the presence of nano-particle of Fe 3O 4. The microspheres were characterized by FTIR spectra. They were used as carrier to immobilize bovine serum albumin (BSA). To investigate the effect of the microsphere surface properties on the immobilization of BSA, a series of microspheres with different hydrophobic/hydrophilic surface characteristics were prepared by adjusting molar percentages of monomers. The results showed that microspheres with different hydrophobicities/hydrophilicities had different immobilized ratios of BSA. In comparison with microspheres having hydrophilic characteristics those with hydrophobic characteristics had a much higher immobilized ratio. The possible reasons for these observations are discussed. In addition, ester activation and coupling times were optimized with respect to immobilized ratio.

A simple method for the preparation of monodisperse protein-loaded microspheres with high encapsulation efficiencies

A simple method for the preparation of monodisperse protein-loaded polymer microspheres is presented in this paper. The method is based on the co-extrusion of an internal phase of an aqueous protein solution and an external phase of an organic polymer solution through a 200-micron-sized hole. Controlled in the correct flow region, this process produces a core–shell-structured laminar liquid jet, which breaks to form monodisperse compound liquid droplets. Stabilized in a dilute aqueous polyvinyl alcohol (PVA) solution, the droplets are converted into solid protein-loaded polymer microspheres through evaporation of the organic solvent. Results show that preparation parameters such as polymer concentration, total flow rate, flow rate ratio of the aqueous to organic phase have significant effects on the mean particle size, particle morphology and protein encapsulation efficiency (EE). The results of biodegradation and the protein release characteristics of the polymer microspheres are also presented.

Direct electrochemistry of hemoglobin in a nafion and CuS microsphere modified carbon ionic liquid electrode and its electrocatalytic behavior

Direct electrochemistry of hemoglobin (Hb) was realized on a Nafion and CuS microsphere composite film modified carbon ionic liquid electrode (CILE) with N-butylpyridinium hexafluorophosphate (BPPF6) as binder. Scanning electron microscopy (SEM), UV-Vis absorption spectroscopy and cyclic voltammetry were used to characterize the fabricated Nafion/CuS/Hb/CILE. Experimental results showed that a pair of well-defined quasi-reversible redox peaks appeared with the formal potential as -0.386 V (vs. SCE) in pH 7.0 Britton-Robinson (B-R) buffer solution, which was attributed to the Hb heme Fe(III)/Fe(II) redox couples. The electrochemical parameters of Hb in the composite film were carefully investigated with the charge transfer coefficient (α), the electron transfer number (n) and the electron transfer rate constant (ks) as 0.505, 1.196 and 0.610 s -1 , respectively. The composite film provided a favorable microenvironment for retaining the native structure of Hb. The presence of CuS microspheres showed great improvement on the electron transfer rate of Hb with the CILE, which maybe due to the contribution of specific characteristics of CuS microspheres and the inherent advantages of ionic liquid on the modified electrode. The fabricated Hb modified electrode showed good electrocatalytic ability in the reduction of H2O2. The proposed bioelectrode can be used as a new third generation H2O2 biosensor.

Effect of ethanol as a processing co-solvent on the PLGA microsphere characteristics

The effect of ethanol, as an organic phase co-solvent, on the characteristics of dexamethasone containing poly(lactide-co-glycolide) (PLGA) microspheres prepared via the emulsion–solvent evaporation/extraction process has been evaluated. This study allowed determination of the maximum amount of ethanol that can be used to prepare radio-labeled dexamethasone microspheres without affecting their performance. Different ethanol co-solvent concentrations (0–43.75% (v/v)) were investigated and changes in the physicochemical properties and in vitro release profiles were determined. A significant decrease in particle size and drug loading was observed at 12.50% and 25% (v/v) ethanol concentrations, respectively. Morphological evaluation revealed the presence of drug crystals on the microsphere surfaces prepared using ethanol co-solvent concentrations of 18.75% (v/v) and higher. A high burst release was observed with these formulations due to the presence of drug crystals on microsphere surfaces. Various competing factors such as interfacial tension between methylene chloride and water, solubility of drug in the organic phase and the viscosity of the polymer phase contributed to the changes observed in microspheres characteristics at different ethanol co-solvent concentrations. It was determined that radio-labeled dexamethasone solution (in ethanol) can be used at concentrations up to 12.5% (v/v) of organic phase without any significant change in microsphere characteristics.

Prednisolone-loaded PLGA microspheres. in vitro characterization and in vivo application in adjuvant-induced arthritis in mice.

This study aimed at preparation of a sustained-release steroidal treatment for chronic inflammatory conditions, such as rheumatoid arthritis. To achieve such a goal, biodegradable poly-lactide-co-glycolide prednisolone-loaded microspheres were prepared using o/w emulsion solvent evaporation method. Formulation parameters were adjusted so as to optimize the microsphere characteristics. The prepared microspheres exhibited smooth and intact surfaces, with average size range not exceeding 65 microm. The encapsulation efficiency percent of most microsphere formulations fell within the range of 25-68%. Drug release from these microspheres took place over 4 weeks, with near-to-zero-order patterns. Two successful formulations were chosen for the treatment of unilateral arthritis, induced in mice using Freund's complete adjuvant (FCA). Inflammatory signs of adjuvant arthritis included severe swelling of the FCA-injected limbs, in addition to many histopathological lesions. These included inflammatory cell infiltration, synovial hyperplasia, cartilage, and bone erosion. Parenteral administration of the selected formulae dramatically reduced the swelling of the FCA-injected limbs. In addition, histological examination revealed that the microsphere treatment protocol efficiently protected cartilages and bones of mice, injected with FCA initial and booster doses, from erosion. These results could not be achieved by a single prednisolone dose of 5 mg/kg.

Ondansetron-loaded biodegradable microspheres as a nasal sustained delivery system: In vitro/in vivo studies

The aim of this study was to prepare ondansetron-loaded biodegradable microspheres as a nasal delivery system. Microspheres were prepared with emulsification/spray-drying technique using poly(d,l-lactide) (PLA) and two different types of poly(d,l-lactide-co-glycolide) (PLGA). The effect of the type of organic solvent (dichloromethane (DCM) or a mixture of DCM and ethyl acetate) on the microsphere characteristics was also examined. The prepared microspheres were evaluated with respect to the morphological properties, particle size, zeta potential, drug loading efficiency, and in vitro drug release. The mean particle size (d50) of microsphere formulations was ranged from 11.67–25.54 μm, indicating suitable particle size for nasal administration. All microspheres had low drug loading efficiency in the range of 12.28–21.04%. The results indicated that particle size of microspheres were affected by both type of polymer and organic solvent, however drug loading efficiency of microspheres were affected by only the type of organic solvent used. All microspheres were negatively charged due to the polymers (PLA or PLGA) used. A prolonged in vitro drug release profile was observed for 96 h. Based on in vitro data, the selected microsphere formulation has been applied via nasal route to rats in vivo. Following nasal administration of ondansetron-loaded microsphere to rats, ondansetron plasma levels were within a range of 30–48 ng/mL during 96 h, indicating a sustained drug delivery pattern and relatively a constant plasma drug concentration level. The results suggested that biodegradable microspheres prepared with emulsification/spray-drying technique could be considered to deliver ondansetron via nasal route to obtain a prolonged release.

Effect of the molecular weight of poly(ethylene glycol) used as emulsifier on α-chymotrypsin stability upon encapsulation in PLGA microspheres

Poly(ethylene glycol) (PEG) was used as emulsifier to prepare alpha-chymotrypsin-loaded poly(lactic-co-glycolic) acid (PLGA) microspheres by a solid-in-oil-in-water (s/o/w) technique. The effect of the molecular weight of PEG on protein stability was assessed by the determination of the amount of insoluble aggregates, the activity loss and the magnitude of structural perturbations. In addition, the effect of the molecular weight of PEG on the encapsulation efficiency, microsphere characteristics and release kinetics was investigated. X-ray photoelectron spectroscopy (XPS) was employed to characterize the surface chemistry of the microspheres. Microspheres were prepared using PEG with molecular weight of 6,000, 8,000, 10,000, 12,000 and 20,000. The results indicate that PEG 20,000 was the most effective emulsifier when producing alpha-chymotrypsin-loaded microspheres with respect to protein stability. The aggregate formation was decreased from 18% to 3%; the protein inactivation and the encapsulation-induced structural perturbations were largely prevented. XPS confirmed that PEG was largely located on the surface of microspheres. The molecular weight of PEG affected the microspheres' characteristics and release kinetics. Microspheres prepared with PEG 20,000 showed improved encapsulation efficiency (80%) and a continuous release (for 50 days) with the lowest amount of initial release. It is demonstrated that the selection of the optimum molecular weight of PEG when used as emulsifier in the preparation of microspheres is a critical factor in the development of sustained-release formulations for the delivery of proteins.

Inhibition of serum angiotensin-converting enzyme in rabbits after intravenous administration of enalaprilat-loaded intact erythrocytes.

Encapsulation of drugs in intact erythrocytes, because of the profound characteristics of these natural microspheres, has gained considerable attention in recent years. In this study, the inhibition time courses of serum angiotensin-converting enzyme (ACE) activity after intravenous administration of enalaprilat encapsulated in intact erythrocytes was evaluated and compared with free drug, in a rabbit model. Three groups of animals each received free drug, drug-loaded erythrocytes or sham-encapsulated erythrocytes. Serum ACE activity was determined in each case using the synthetic substrate hippuryl-histidyl-leucine and quantitation of the hippuric acid released by a developed and validated HPLC method. The serum ACE inhibition profiles in the three groups showed that the encapsulated drug inhibited the serum ACE more slowly, more efficiently, over a considerably longer time and in a more reproducible manner, than the free drug or sham-encapsulated erythrocytes. We conclude that the erythrocytes can serve as efficacious slow-release drug carriers for enalaprilat in circulation.

Uniform polyaniline microspheres: A novel adsorbent for dye removal from aqueous solution

Uniform polyaniline (PANI) microspheres were synthesized by a facile polymerization of aniline monomer in the acidic medium. The structure and morphology of PANI microspheres were characterized by means of FTIR spectrometer, X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). Adsorption characteristics of PANI microspheres were examined using methyl orange (MO) as adsorbate. Batch adsorption experiments were carried out to investigate adsorption kinetics and isotherms of PANI microspheres. Adsorption equilibrium studies showed that MO adsorption followed Freundlich model. The adsorption kinetics was best described by pseudo-second-order model. The results indicated that PANI microspheres can be used as a novel, effective and low-cost adsorbent material for dye removal.

Preparation and characteristics of porous CuS microspheres consisted of polycrystalline nanoslices

This paper presents a facile method to fabricate CuS porous microspheres, which were formed by the intergrowth of CuS polycrystalline nanoslices. The obtained sample has been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electronic diffraction (SAED), X-ray diffraction (XRD), UV–vis diffusion reflection and Laser Raman. On the basis of the experimental results, we proposed a self-assemble mechanism to elucidate the formation of CuS nanoslice structure. The current–voltage characteristic under different gas atmospheres shows that the as prepared CuS polycrystalline nanoslices are sensitive to ammonia at ppm level and the electrical conductivity is found to be weaker in ammonia than that in air.

Formulation and Evaluation of Propranolol Hydrochloride-Loaded Carbopol-934P/Ethyl Cellulose Mucoadhesive Microspheres.

The purpose of this research was to formulate and systemically evaluate in-vitro and in-vivo performances of mucoadhesive propranolol hydrochloride microspheres for its potential use in the treatment of hypertension, myocardial infraction and cardiac arrhythmias. Propranolol hydrochloride mucoadhesive microspheres, containing carbopol-934P as mucoadhesive polymer and ethyl cellulose as carrier polymer, were prepared by an emulsion-solvent evaporation technique. Results of preliminary trials indicated that the quantity of emulsifying agent, time for stirring, drug-to-polymers ratio, and speed of rotation affected various characteristics of microspheres. Microspheres were discrete, spherical, free-flowing and showed a good percentage of drug entrapment efficiency. An in-vitro mucoadhesive test showed that propranolol hydrochloride mucoadhesive microspheres adhered more strongly to the gastric mucous layer and could be retained in the gastrointestinal tract for an extended period of time. A 3(2) full factorial design was employed to study the effect of independent variables, drug-to-polymer-to-polymer ratio (propranolol hydrochloride-ethyl cellulose-carbopol-934P) (X 1), and stirring speed (X 2) on dependent variables, i.e. percentage of mucoadhesion, drug entrapment efficiency, particle size and t80. The best batch exhibited a high drug entrapment efficiency of 54 %; 82% mucoadhesion after 1 h and particle size of 110 μm. A sustained pattern of drug release was obtained for more than 12 h. The drug-to-polymer-to-polymer ratio had a more significant effect on the dependent variables. The morphological characteristics of the mucoadhesive microspheres were studied under a scanning electron microscope. In-vivo evaluation studies on propranolol hydrochloride mucoadhesive microspheres and propranolol hydrochloride powder were performed on normal healthy rabbits. The results showed a sustained anti-hypertensive effect over a longer period of time in case of mucoadhesive microspheres, compared to the powder. In conclusion, the prolonged gastrointestinal residence time and slow release of propranolol hydrochloride resulting from the mucoadhesive microspheres, could contribute to the provision of a sustained anti-hypertensive effect.

Preparation and In-vitro Evaluation of Controlled Release PLGA Microparticles Containing Triptoreline.

Triptoreline is a potent agonist of luteinizing hormone-releasing hormone, currently used in the treatment of prostatic cancer where therapy may be required over months or years. Frequent injection of drug decreases patients' compliance. The present study describes the formulation of a sustained release microparticulate drug delivery system containing triptoreline acetate, using poly (D,L lactide-co-glycolide) (PLGA). Biodegradable microspheres were prepared using 50 : 50 PLGA by a water in-oil-in-water (w/o/w) double emulsion-solvent evaporation procedure and characterized for drug content and drug release rate using the a HPLC method, particle size distribution using the laser diffraction method, and surface morphology using scanning electron microscopy and drug release rate. Effect of critical process parameters and formulation variables; i.e. volume of inner water phase, addition of NaCl to the outer aqueous phase (W2), addition of different types and amounts of emulsifying agents on microsphere characteristics; were investigated. Microspheres prepared were spherical with a smooth surface, but addition of poloxamer to the first emulsion produced microspheres with large pores. Size of microparticles was dependent on the type, as well as the amount of co-encapsulated surfactants. Increasing the inner water phase volume resulted in larger particles with a lower encapsulation efficiency. Low concentrations of Span 20 decreased triptoreline release rate, whereas the addition of poloxamer or high concentrations of Span 20 increased the drug release rateit. In conclusion, by selecting an appropriate level of the investigated parameters, spherical microparticles with encapsulation efficiencies higher than 90% and a prolonged triptoreline release over 45 days were obtained.

Effect of formulation and processing variables on the characteristics of tolmetin microspheres prepared by double emulsion solvent diffusion method

The aim of this study was to evaluate microencapsulated controlled release preparations of tolmetin sodium using ethylcellulose as a retardant material. Microspheres were prepared by using water-in-oil-in-oil (W/O1/O2) double-emulsion solvent diffusion method, using different ratios of ethylcellulose to tolmetin sodium. Span 80 was used as the droplet stabilizer and n-hexane was added to harden the microspheres. The prepared microspheres were characterized for their micromeritic properties, drug content, loading efficiency, production yield, and particle size. Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray powder diffractometry and scanning electron microscopy were used to characterize microparticles. The in vitro release studies were performed in pH 1.2 and 7.4. The prepared microspheres were spherical in shape. The drug-loaded microspheres showed near to the theoretical of entrapment and release was extended up to 24. The X-ray diffractogram and differential scanning thermographs showed amorphous state of the drug in the microspheres. It was shown that the drug: polymer ratio, stirring rate, volume of dispersing medium and surfactant influenced the drug loading, particle size and drug release behavior of the formed microparticles. The results showed that, generally, an increase in the ratio of drug: polymer (0.5:1) resulted in a reduction in the release rate of the drug which may be attributed to the hydrophobic nature of the polymer. The in vitro release profile could be modified by changing various processing and formulation parameters to give a controlled release of drug from the microparticules. The release of tolmetin was influenced by the drug to polymer ratio and particle size and was found to be diffusion and erosion controlled. The best-fit release kinetic was achieved with Peppas model.

Thermonuclear burn characteristics of compressed deuterium-tritium microspheres

The thermonuclear burn characteristics of compressed deuterium-tritium microspheres are simulated with LARED-S code based on the isochoric and isobaric models. Two examples of the isochoric model are simulated and compared with the other present data for validating the LARED-S code. For the isobaric model, numerical results characterizing the thermonuclear burn for a broad range of initial conditions are presenteal. It is shown that the yield and burn-up fraction increase with the total fuel mass, pressure and main-fuel density. It is necessary for the hot-spot to reach temperatures up to 70 to 80 MK and areal density 3 to 4 kg· m-2 to obtain considerable fusion energy. If the main-fuel density is increased high enough, the hot-spot condition for ignition could be broadened to a lower limit. Finally, the results of the isobaric model are compared with those of the actual ignition targets simulated with the LARED-S code.