Differences in attributes between color difference and color appearance (chroma and hue) for near‐neutral colors

Chroma‐step perception and its corresponding color difference in the same hue direction are the different attributes on color perception. The differences between them are different for different hues. Hue‐appearance step and its corresponding color difference along the same hue circle also have completely different concepts. The causes of the above two facts are clarified. The information based on various experiments and theoretical considerations are given for supporting the facts. In addition, it is clarified that the relationship on color‐appearance step and color difference has completely different characteristics between the quantitative (chroma) and the qualitative (hue) attributes of object colors. The importance of chromatic strength (CS) on hue is clarified in each of the three color attributes hue, value, and chroma. © 2004 Wiley Periodicals, Inc. Col Res Appl, 30, 42–52, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20073     

Preparation and evaluation of self-healing microcapsules for asphalt based on response surface optimization

The purpose of this study is to explore the best preparation process of asphalt self-healing microcapsules. Response surface design and single factor design were used to optimize the preparation process parameters of asphalt self-healing microcapsules, and the prediction model of core content was established. The optimal preparation process was determined. The results of response surface design showed that the interaction among emulsifier concentration/reaction temperature, core-shell ratio/reaction temperature, and pH/reaction temperature had significant effect on the core content of microcapsules; the microcapsules prepared by the optimal process were spherical with an average particle size of 90.19 μm. The results of thermogravimetric analysis (TGA) and heating simulation test showed that the microcapsule can delay the damage of the core in high temperature environment; the results of nanoindentation test showed that the young's modulus and hardness of the microcapsules were about 2.50 and 0.28 GPa, respectively. Finally, the improvement mechanism of self-healing performance of asphalt by microcapsules was revealed by fluorescence microscope.     

Supercritical fluid extraction and convergence chromatographic determination of parthenolide in Tanacetum parthenium L.: Experimental design,modeling and optimization

Feverfew (Tanacetum parthenium L., Asteraceae) is a perennial medicinal plant which has been used to alleviate the symptoms of migraines, headaches and rheumatoid arthritis. The herb contains various potentially active constituents such as sesquiterpene-γ-lactones, flavonoids and volatile oil. The main sesquiterpene-lactone in feverfew is parthenolide which is considered to be responsible for the therapeutical effects. Supercritical CO₂ extraction was carried out at different pressures (10–30 MPa), temperatures (40–80 °C) and co-solvent contents (0–10% ethanol) in order to study the extraction yield and the parthenolide recovery of the extracts. Leaves collected before and during flowering and flower heads were investigated. A factorial experiment using a full 3³ design was followed during the experiments and response surface methodology was implemented to analyze the influence of the variables and optimize the extraction. The critical values of parthenolide content were found to be 7% EtOH, 22 MPa and 64 °C in case of all three samples. It was determined, that the optimal conditions of the extraction, where the maximum parthenolide content and extract yield can be reached, do not coincide. The highest yield of parthenolide was obtained in the flower heads (0.604 wt.%).     

Supercritical carbon dioxide extraction of oil from Mexican chia seed (Salvia hispanica L.): Characterization and process optimization

Supercritical carbon dioxide (SC-CO₂) was employed to extract oil rich in omega-3 fatty acids (FAs) from chia seeds, and the physicochemical properties of the oil were determined. A central composite rotatable design was used to analyze the impact of temperature (40 °C, 60 °C and 80 °C), pressure (250 bar, 350 bar and 450 bar) and time (60 min, 150 min and 240 min) on oil extraction yield, and a response surface methodology (RSM) was applied. The extraction time and pressure had the greatest effects on oil. The highest oil yield was 92.8% after 300 min of extraction time at 450 bar. The FA composition varied depending on operating conditions but had a high content of α-linolenic acid (44.4-63.4%) and linoleic acid (19.6-35.0%). The rheological evaluation of the oils indicated a Newtonian behavior. The viscosity of the oil decreased with the increase in temperature following an Arrhenius-type relationship.     

Optimization and analysis of nickel adsorption on microwave irradiated rice husk using response surface methodology (RSM)

BACKGROUND: The removal of heavy metals using adsorption techniques with low cost biosorbents is being extensively investigated. The improved adsorption is essentially due to the pores present in the adsorbent. One way of improving the porosity of the material is by irradiation of the precursor using microwaves. In the present study, the adsorption characteristics of nickel onto microwave‐irradiated rice husks were studied and the process variables were optimized through response surface methodology (RSM). RESULT: The adsorption of nickel onto microwave‐irradiated rice husk (MIRH) was found to be better than that of the raw rice husk (RRH). The kinetics of the adsorption of Ni(II) from aqueous solution onto MIRH was found to follow a pseudo‐second‐order model. Thermodynamic parameters such as standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) were also evaluated. The thermodynamics of Ni(II) adsorption onto MIRH indicates that it is spontaneous and endothermic in nature. The response surface methodology (RSM) was employed to optimize the design parameters for the present process. CONCLUSION: Microwave‐irradiated rice husk was found to be a suitable adsorbent for the removal of nickel(II) ions from aqueous solutions. The adsorption capacity of the rice husk was found to be 1.17 mg g^?1. The optimized parameters for the current process were found as follows: adsorbent loading 2.8 g (100 mL)^?1; Initial adsorbate concentration 6 mg L^?1; adsorption time 210 min.; and adsorption temperature 35 °C. Copyright © 2008 Society of Chemical Industry     

Modeling,prediction, and multifactorial optimization of radiation‐induced grafting of 4‐vinylpyridine onto poly(vinylidene fluoride) films using statistical simulator

The traditional method for obtaining best combination of reaction parameters for graft copolymerization of 4‐vinylpyridine onto poly(vinylidene fluoride) films was modified using Box‐Behnken factorial design available in the response surface method (RSM). A computer‐assisted statistical simulator was used to obtain the optimum absorbed dose, monomer concentration, grafting time and reaction temperature to achieve the highest degree of grafting (G%) based a quadratic model. The validity of the developed model was confirmed by experimental data, which only deviated by a 2% from the predicted value of G% confirming the effectiveness of RSM in optimization of the reaction parameters in the present grafting system. A comparison was also made between the obtained model and that of 1‐vinylimidazole/poly(ethylene‐co‐tetrafluoroethylene) grafting system. The chemical structure, morphology and thermal stability of the obtained graft copolymers was investigated by means of Fourier transform infrared, filed emission scanning electron microscope, and thermogravimetric analysis, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Modeling and optimization of the process parameters in vacuum drying of culinary banana (Musa ABB) slices by application of artificial neural network and genetic algorithm

The influence of drying temperature, sample slice thickness, and pretreatment on quality attributes like rehydration ratio, scavenging activity, color (in terms of nonenzymatic browning), and texture (in terms of hardness) of culinary banana (Musa ABB) has been evaluated in the present study. A comparative approach was made between artificial neural network (ANN) and response surface methodology (RSM) to predict various parameters for vacuum drying of culinary banana. The effect of process variables on responses during dehydration were investigated using general factorial experimental design. This design was used to train feed-forward back-propagation ANN. The predictive capabilities of these two methodologies for optimization of process parameters were compared in terms of relative deviation (R_d). Results revealed that a properly trained ANN model is found to be more accurate in prediction as compared to RSM. The optimum condition selected from ANN/GA responses on the basis of highest fitness value revealed that culinary banana slices of 6 mm thickness pretreated with 1% citric acid and dried at 76°C resulted in a maximum rehydration ratio of 6.20, scavenging activity of 48.63% with minimum nonenzymatic browning of 25%, and hardness of 43.63 N. Results further revealed that, in the case of rehydration ratio, temperature and pretreatment showed a positive effect while thickness had a negative effect. On the contrary, for scavenging activity, temperature showed the highest negative effect followed by slice thickness and positive effect with pretreatment. For nonenzymatic browning, thickness showed the highest negative effect but temperature and pretreatment showed a positive effect. Similarly, for hardness, all three parameters showed a negative effect.     

Global Identification and Characterization of C2 Domain-Containing Proteins Associated with Abiotic Stress Response in Rice (Oryza sativa L.)

C2 domain-containing proteins (C2DPs) have been identified in different genomes that contain single or multiple C2 domains in their C- or N-terminal. It possesses higher functional activity in the transmembrane regions. The identification of C2 domains were reported in a previous study, such as multiple C2 domains and transmembrane-region proteins (MCTPs) and N-terminal-TM-C2 domain proteins (NTMC2s) of rice, Arabidopsis thaliana, and cotton, whereas the C2DP gene family in rice has not been comprehensively studied, and the role of the C2DP gene in rice in response to abiotic stress is not yet fully understood. In this study, we identified 82 C2DPs in the rice genome and divided them into seven groups through phylogenetic analysis. The synteny analysis revealed that duplication events were either exhibited within the genome of rice or between the genomes of rice and other species. Through the analysis of cis-acting elements in promoters, expression profiles, and qRT-PCR results, the functions of OsC2DPs were found to be widely distributed in diverse tissues and were extensively involved in phytohormones-related and abiotic stresses response in rice. The prediction of the microRNA (miRNA) targets of OsC2DPs revealed the possibility of regulation by consistent miRNAs. Notably, OsC2DP50/51/52 as a co-tandem duplication exhibited similar expression variations and involved the coincident miRNA-regulation pathway. Moreover, the results of the genotypic variation and haplotype analysis revealed that OsC2DP17, OsC2DP29, and OsC2DP49 were associated with cold stress responses. These findings provided comprehensive insights for characterizations of OsC2DPs in rice as well as for their roles for abiotic stress.     

Parameter optimization for the oxidative coupling of methane in a fixed bed reactor by combination of response surface methodology and computational fluid dynamics

A resource and time saving method is introduced for optimizing fixed bed reactors by the combination of response surface methodology (RSM) and CFD simulation. This is demonstrated for the oxidative coupling of methane (OCM) based on the reaction kinetics by Stansch et al. (1997). Firstly, a parameter screening is performed to identify the power factors modified reaction time, heating temperature and CH₄ to O₂ ratio. Secondly, utilizing Central Composite Design, meta models for the most interesting responses are developed, i.e. C₂ selectivity and yield as well as CH₄ conversion. The statistical models describe the characteristics of the responses over a wide range. Thirdly, an optimization of C₂ yield is carried out using RSM. The maximum is detected to be approx. 14% and validated by three dimensional CFD simulations. In the investigated parameter space the optimized parameter conditions are found for a feed composition of 20% nitrogen, 26.7% oxygen, 53.3% methane (CH₄ to O₂ ratio of 2), a modified reaction time of 61 kg s/m³ and a heating temperature of 801.5 °C.     

Enhancement of Palmarumycins C12 and C13 Production in Liquid Culture of Endophytic Fungus Berkleasmium sp. Dzf12 after Treatments with Metal Ions

The influences of eight metal ions (i.e., Na⁺, Ca²⁺, Ag⁺, Co²⁺, Cu²⁺, Al³⁺, Zn²⁺, and Mn⁴⁺) on mycelia growth and palmarumycins C₁₂ and C₁₃ production in liquid culture of the endophytic fungus Berkleasmium sp. Dzf12 were investigated. Three metal ions, Ca²⁺, Cu²⁺ and Al³⁺ were exhibited as the most effective to enhance mycelia growth and palmarumycin production. When calcium ion (Ca²⁺) was applied to the medium at 10.0 mmol/L on day 3, copper ion (Cu²⁺) to the medium at 1.0 mmol/L on day 3, aluminum ion (Al³⁺) to the medium at 2.0 mmol/L on day 6, the maximal yields of palmarumycins C₁₂ plus C₁₃ were obtained as 137.57 mg/L, 146.28 mg/L and 156.77 mg/L, which were 3.94-fold, 4.19-fold and 4.49-fold in comparison with that (34.91 mg/L) of the control, respectively. Al³⁺ favored palmarumycin C₁₂ production when its concentration was higher than 4 mmol/L. Ca²⁺ had an improving effect on mycelia growth of Berkleasmium sp. Dzf12. The combination effects of Ca²⁺, Cu²⁺ and Al³⁺ on palmarumycin C₁₃ production were further studied by employing a statistical method based on the central composite design (CCD) and response surface methodology (RSM). By solving the quadratic regression equation between palmarumycin C₁₃ and three metal ions, the optimal concentrations of Ca²⁺, Cu²⁺ and Al³⁺ in medium for palmarumycin C₁₃ production were determined as 7.58, 1.36 and 2.05 mmol/L, respectively. Under the optimum conditions, the predicted maximum palmarumycin C₁₃ yield reached 208.49 mg/L. By optimizing the combination of Ca²⁺, Cu²⁺ and Al³⁺ in medium, palmarumycin C₁₃ yield was increased to 203.85 mg/L, which was 6.00-fold in comparison with that (33.98 mg/L) in the original basal medium. The results indicate that appropriate metal ions (i.e., Ca²⁺, Cu²⁺ and Al³⁺) could enhance palmarumycin production. Application of the metal ions should be an effective strategy for palmarumycin production in liquid culture of the endophytic fungus Berkleasmium sp. Dzf12.