Solubility enhancement of miconazole nitrate: binary and ternary mixture approach

Context: Enhancement of aqueous solubility of very slightly soluble Miconazole Nitrate (MN) is required to widen its application from topical formulation to oral/mucoadhesive formulations.

Objective: Aim of the present investigation was to enhance the aqueous solubility of MN using binary and ternary mixture approach.

Materials and methods: Binary mixtures such as solvent deposition, inclusion complexation and solid dispersion were adopted to enhance solubility using different polymers like lactose, beta-cyclodextrin (β-CD) and polyethylene-glycol 6000 (PEG 6000), respectively. Batches of binary mixtures with highest solubility enhancement potentials were further mixed to form ternary mixture by a simple kneading method. Drug polymer interaction and mixture morphology was studied using the Fourier transform infrared spectroscopy and the scanning electron microscopy, respectively along with their saturation solubility studies and drug release.

Results: An excellent solubility enhancement, i.e. up to 72 folds and 316 folds of MN was seen by binary and ternary mixture, respectively. Up to 99.5% drug was released in 2?h from the mixtures of MN and polymers.

Discussion: Results revealed that solubility enhancement by binary mixtures is achieved due to surface modification and by increasing wettability of MN. Tremendous increase in solubility of MN by ternary mixture could possibly be due to blending of water soluble polymers, i.e. lactose and PEG 6000 with β-CD which was found to enhance the solubilizing nature of β-CD.

Conclusion: Owing to the excellent solubility enhancement potential of ternary mixtures in enhancing MN solubility from 110.4?μg/ml to 57?640.0?μg/ml, ternary mixture approach could prove to be promising in the development of oral/mucoadhesive formulations.     

Revealing characteristics of mixed consortia for azo dye decolorization: Lotka-Volterra model and game theory

This study provides a novel explanation to put forward, in Lotka-Volterra competition model and game theory, interspecific competition in bioaugmentation using constructed mixed consortia for azo dye decolorization. As mixed cultures are regularly used in industrial dye-laden wastewater treatment, understanding species competition of mixed consortia is apparently of great importance to azo dye decolorization. In aerobic growth conditions, Escherichia coli DH5alpha owned a growth advantage to out-compete Pseudomonas luteola due to preferential growth rate of DH5alpha. However, in static decolorization conditions DH5alpha surrendered some proportion of its advantage (i.e., a decrease in its competitive power for metabolite stimulation) to enhance color removal of P. luteola for total coexistence. In aerobic growth, DH5alpha had its growth advantage to exclude P. luteola for dominance (i.e, conflict strategy) according to competitive exclusion principle. In static decolorization conditions, as the removal of a common dye threat was crucial to both species for survival, both species selected cooperation strategy through metabolite stimulation of DH5alpha to enhance effective decolorization of P. luteola for long-term sustainable management. This analysis of game theory clearly unlocked unsolved mysteries in previous studies.     

D-optimal mixture design: optimization of ternary matrix blends for controlled zero-order drug release from oral dosage forms

The objective of the present study was to develop a tablet formulation with a zero-order drug release profile based on a balanced blend of three matrix ingredients. To accomplish this goal, a 17-run, three-factor, two-level D-Optimal mixture design was employed to evaluate the effect of Polyox^™ (X₁), Carbopol® (X₂), and lactose (X₃) concentrations on the release rate of theophylline from the matrices. Tablets were prepared by direct compression and were subjected to an in vitro dissolution study in phosphate buffer at pH 7.2. Polynomial models were generated for the responses Y₄ (percent released in 8 h) and Y₆ (similarity factor or f₂). Fitted models were used to predict the composition of a formulation that would have a similar dissolution profile to an ideal zero-order release at a rate of 8.33% per hour. When tested, dissolution profile of the optimized formulation was comparable to the reference profile (f₂ was 74.2, and n [release exponent] was 0.9). This study demonstrated that a balanced blend of matrix ingredients could be used to attain a zero-order release profile. Optimization was feasible by the application of response surface methodology, which proved efficient in designing controlled-release dosage forms.     

A statistical experiment design approach for advanced oxidation of Direct Red azo-dye by photo-Fenton treatment

Advanced oxidation of an azo-dye, Direct Red 28 (DR 28) by photo-Fenton treatment was investigated in batch experiments using Box-Behnken statistical experiment design and the response surface analysis. Dyestuff (DR 28), H(2)O(2) and Fe(II) concentrations were selected as independent variables in Box-Behnken design while color and total organic carbon (TOC) removal (mineralization) were considered as the response functions. Color removal increased with increasing H(2)O(2) and Fe(II) concentrations up to a certain level. High concentrations of H(2)O(2) and Fe(II) adversely affected the color and TOC removals due to hydroxyl radical scavenging effects of high oxidant and catalyst concentrations. Both H(2)O(2) and Fe(II) concentration had profound effects on decolorization. Percent color removal was higher than TOC removal indicating formation of colorless organic intermediates. Complete color removal was achieved within 5min while complete mineralization took nearly 15min. The optimal reagent doses varied depending on the initial dyestuff dose. For the highest dyestuff concentration tested, the optimal H(2)O(2)/Fe(II)/dyestuff ratio resulting in the maximum color removal (100%) was predicted to be 715/71/250 (mgL(-1)), while this ratio was 1550/96.5/250 for maximum mineralization (97.5%).     

3D numerical simulations of thermodiffusion experiment for a ternary mixture on-board foton

The phenomenon of mass flux in a mixture due to a temperature gradient is known as the Soret effect. Accurate experimental and theoretical models are needed for a better understanding and effective characterisation of situations involving coupled transport processes as in hydrocarbon reservoirs. This requires precise knowledge of the transport coefficients particularly the Fick and Soret diffusion coefficients. We have investigated the effect of residual-g and (very) low-frequency g-jitters encountered on-board spacecraft FOTON on mass-thermo-fluid dynamics in the presence of Soret effect. Results revealed that the diffusion process is slightly affected by the g-jitter on board the FOTON platform, which indicates that FOTON is a good platform to conduct near perfect microgravity environment.     

High-energy sensitivity enhancement in panchromatic photopolymers for holography using a mixture of visiblelight photoinitiators

Abstract

A new aqueous photopolymer containing the monomers acrylamide, N,N'-methylenbisacrylamide and zinc acrylate, the initiators 4,5-diiodosuccinylfluorescein (2ISF) and methylene blue (MB), and the coinitiator sodium p-toluenesulphinate is described. This formulation exhibits a clear enhancement of the high-energy sensitivity upon irradiation with 514 or 633 nm light (Ar⁺ laser or He–Ne laser respectively), with respect to the same mixture but with only one of the two dyes, reaching maximum diffraction efficiencies of 15–20% with 15–60 mJ cm^?2. This enhancement is explained by the more efficient photogeneration of initiator radicals by the ground-state formation of an ion-pair complex between cationic (MB) and anionic (2ISF) chromophores. This must compensate the observed decrease in the absorbance of the mixture of the two dyes at 514 nm, with respect to the absorbance of the same medium but with only 2ISF (maximum absorption at 490 nm). A clear absorbance increase at 633 nm, with respect to the absorbance of this system with only MB (maximum absorption at 660 nm), must also favour photopolymerization.     

Optimization of process variables for decolorization of Disperse Yellow 211 by Bacillus subtilis using Box-Behnken design

Decolorization of textile azo dye Disperse Yellow 211 (DY 211) was carried out from simulated aqueous solution by bacterial strain Bacillus subtilis. Response surface methodology (RSM), involving Box-Behnken design matrix in three most important operating variables; temperature, pH and initial dye concentration was successfully employed for the study and optimization of decolorization process. The total 17 experiments were conducted in the study towards the construction of a quadratic model. According to analysis of variance (ANOVA) results, the proposed model can be used to navigate the design space. Under optimized conditions the bacterial strain was able to decolorize DY 211 up to 80%. Model indicated that initial dye concentration of 100 mgl(-1), pH 7 and a temperature of 32.5 degrees C were found optimum for maximum % decolorization. Very high regression coefficient between the variables and the response (R(2)=0.9930) indicated excellent evaluation of experimental data by polynomial regression model. The combination of the three variables predicted through RSM was confirmed through confirmatory experiments, hence the bacterial strain holds a great potential for the treatment of colored textile effluents.     

Use of ejectors in a multi-evaporator refrigeration system for performance enhancement

In this study, an improved cooling cycle for a conventional multi-evaporators simple compression system utilizing ejector for vapour precompression is analyzed. The ejector-enhanced refrigeration cycle consists of multi-evaporators that operate at different pressure and temperature levels. A one-dimensional mathematical model of the ejector was developed using the equations governing the flow and thermodynamics based on the constant-area ejector flow model. The model includes effects of friction at the constant-area mixing chamber. The energy efficiency and the performance characteristics of the novel cycle are theoretically investigated. The comparison between the novel and conventional system was made under the same operating conditions. Also, a comparison of the system performances with environment friendly refrigerants (R290, R600a, R717, R134a, R152a, and R141b) is made. The theoretical results show that the COP of the novel cycle is better than the conventional system.     

主动减振器结构参数优化设计

主动减振系统由3个以上减振器构成,其固有频率直接决定了系统隔振带宽,且减振器水平向隔振广泛采用摆机构。柔性杆直径及杆长是影响摆机构水平向刚度的主要几何参数。根据材料弹性变形理论建立了摆机构的水平向刚度模型及最大拉应力模型。在给定的负载质量范围内,以主动减振系统水平向固有频率与目标值的均方差最小作为优化目标,将许用拉应力和最大尺寸作为设计约束,应用序列二次规划法求解该非线性优化模型,得出摆机构的最优设计参数及对应的均方差。基于3σ准则,可估计主动减振系统的水平向固有频率分布范围。在许用固有频率范围约束下,得到摆机构参数的允许范围。实验结果表明:减振系统固有频率的测试值与理论分析值的差异小于10%;加入主动控制后,振动传递率的共振峰小于0dB,大于6Hz的振动传递率小于-20dB。     

Mortar fatigue model for meso-mechanistic mixture design of ravelling resistant porous asphalt concrete

This paper presents the development of a practical mortar fatigue model on the basis of the dissipated energy concept. A specially designed test setup was developed for characterization of mortar fatigue at meso-scale by means of dynamic shear rheometer. Test results showed that mortar fatigue models based on the dissipated energy concept can be developed for the purpose of life predictions under complicated loading conditions. The dissipated energy per cycle in the initial phase of fatigue tests is a practical indicator for fatigue life determination purposes than the total energy dissipated during a fatigue test. Since a mortar fatigue model based on the initial dissipated energy per cycle was adopted, effects of random stress and strain signals on mortar fatigue can be taken into account.     

Feasibility study to control fiber distribution for enhancement of composite properties via three-dimensional printing

The distribution of fibers in the composite (which takes into account both their locations and orientations) is one of the important factors that affect the mechanical properties of FRCs. However, this parameter depends on various factors during composite fabrication, and controlling the distribution of fibers in the produced material represents a significant challenge. In this study, the applicability of three-dimensional (3D) printing technique for controlling fiber distributions was evaluated. The fibers fabricated using a 3D printer were placed inside a mold to produce cementitious composites. Three-point bending tests were conducted and the results of the experiment were discussed.     

Kinetic study approach of remazol black-B use for the development of two-stage anoxic-oxic reactor for decolorization/biodegradation of azo dyes by activated bacterial consortium

The laboratory-isolated strains Pseudomonas aeruginosa, Rhodobacter sphaeroides, Proteus mirabilis, Bacillus circulance, NAD 1 and NAD 6 were observed to be predominant in the bacterial consortium responsible for effective decolorization of the azo dyes. The kinetic characteristics of azo dye decolorization by bacterial consortium were determined quantitatively using reactive vinyl sulfonated diazo dye, remazol black-B (RB-B) as a model substrate. Effects of substrate (RB-B) concentration as well as different substrates (azo dyes), environmental parameters (temperature and pH), glucose and other electron donor/co-substrate on the rate of decolorization were investigated to reveal the key factor that determines the performance of dye decolorization. The activation energy (E(a)) and frequency factor (K(0)) based on the Arrhenius equation was calculated as 11.67 kcal mol(-1) and 1.57 x 10(7)mg lg MLSS(-1)h(-1), respectively. The Double-reciprocal or Lineweaver-Burk plot was used to evaluate V(max), 15.97 h(-1) and K(m), 85.66 mg l(-1). The two-stage anoxic-oxic reactor system has proved to be successful in achieving significant decolorization and degradation of azo dyes by specific developed bacterial consortium with a removal of 84% color and 80% COD for real textile effluents vis-à-vis >or=90% color and COD removal for synthetic dye solution.     

Shape design of cerium oxide nanoparticles for enhancement of enzyme mimetic activity in therapeutic applications

Cerium oxide nanoparticles (CONPs), widely used in catalytic applications owing to their robust redox reaction, are now being considered in therapeutic applications based on their enzyme mimetic properties such as catalase and super oxide dismutase (SOD) mimetic activities. In therapeutic applications, the emerging demand for CONPs with low cytotoxicity, high cost efficiency, and high enzyme mimetic capability necessitates the exploration of alternative synthesis and effective material design. This study presents a room temperature aqueous synthesis for low-cost production of shape-selective CONPs without potentially harmful organic substances, and additionally, investigates cell viability and catalase and SOD mimetic activities. This synthesis, at room temperature, produced CONPs with particular planes: {111}/{100} nanopolyhedra, {100} nano/submicron cubes, and {111}/{100} nanorods that grew in [110] longitudinal direction. Enzymatic activity assays indicated that nanopolyhedra with a high concentration of Ce⁴⁺ ions promoted catalase mimetic activity, while nanocubes and nanorods with high Ce³⁺ ion concentrations enhanced SOD mimetic activity. This is the first study indicating that shape and facet configuration design of CONPs, coupled with the retention of dominant, specific Ce valence states, potentiates enzyme mimetic activities. These findings may be utilized for CONP design aimed at enhancing enzyme mimetic activities in therapeutic applications.

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Biomimetic design of a bacterial cellulose/hydroxyapatite nanocomposite for bone healing applications

This study describes the design and synthesis of bacterial cellulose/hydroxyapatite nanocomposites for bone healing applications using a biomimetic approach. Bacterial cellulose (BC) with various surface morphologies (pellicles and tubes) was negatively charged by the adsorption of carboxymethyl cellulose (CMC) to initiate nucleation of calcium-deficient hydroxyapatite (cdHAp). The cdHAp was grown in vitro via dynamic simulated body fluid (SBF) treatments over a one week period. Characterization of the mineralized samples was done with X-ray Photoelectron Spectroscopy (XPS) and Field Emission Scanning Electron Microscopy (FESEM) with Energy Dispersive Spectroscopy (EDS). The amount of cdHAp observed varied among different samples. XPS demonstrated that the atomic presence of calcium and phosphorus ranged from 0.44 at.% to 7.71 at.% Ca and 0.27 at.% to 11.18 at.% P. The Ca/P overall ratio ranged from 1.22 to 1.92. FESEM images showed that the cdHAp crystal size increased with increasing nanocellulose fibril density. To determine the viability of the scaffolds in vitro, the morphology and differentiation of osteoprogenitor cells was analyzed using fluorescence microscopy and alkaline phosphatase gene expression. The presence of cdHAp crystals on BC surfaces resulted in increased cell attachment.     

Molecular design of TiO2 for gigantic red shift via sublattice substitution

The effects of 3d transition metal doping in TiO2 phases have been simulated in detail. The results of modelling indicate that Mn has the biggest potential among 3d transition metals, for the reduction of energy gap and the introduction of effective intermediate bands to allow multi-band optical absorption. On the basis of theoretical formulation, we have incorporated considerable amount of Mn in nano-crystalline TiO2 materials. Mn doped samples demonstrate significant red shift in the optical absorption edge, with a secondary absorption edge corresponding to theoretically predicted intermediate bands/states. The gigantic red shift achievable in Mn-doped TiO2 is expected to extend the useful TiO2 functionalities well beyond the UV threshold via the optical absorption of both visible and infrared photon irradiance.     

Split-plot design optimization for trace determination of lead by anodic stripping voltammetry in a homogeneous ternary solvent system

A split-plot design has been used to simultaneously optimize reagent conditions and solvent medium for Pb²⁺ determination by anodic stripping voltammetry (ASV). Three mixture components, N,N-dimethylformamide (DMF), ethanol and water, and two process variable levels, ammonium acetate (supporting electrolyte) and hydrochloric acid concentrations, were varied. The calculations of main-plot, subplot and main-subplot interaction ANOVA sums of squares for regression and lack of fit are illustrated. These values are shown to be useful for model development. Six different models were evaluated. The bilinear-special cubic model has only a very slight lack of fit and is preferred. Standard error estimates were calculated using a method described in the literature by Cornell, and approximate critical values for t-tests on the model coefficients were investigated. Normal probability graphs seem appropriate for this analysis. The significant terms in this model are capable of describing how the mixture response surfaces change as process level conditions are varied. Optimized mixture proportions for each factorial design level are determined. Optimum conditions in the (− −) main-plot quadrant for the determination of lead by ASV in the homogeneous ternary solvent system were achieved with a solvent composition of 8.0 g of N,N-dimethylformamide (DMF), 7.0 g of ethanol and 5.0 g of water, corresponding to 40% m/m of DMF, 35% n/m of ethanol and 25% m/m of water. Water is essential since the sample and the buffer (0.1 mol kg⁻¹ ammonium acetate containing 0.00880 mol kg⁻¹ HCl) are added to the system as aqueous solutions. The other three main-plot quadrants presented optimum analytical signals for 95% aqueous solutions. The split-plot design seems to be especially appropriate for simultaneously optimizing process and mixture variables of this chemical system facilitating operational procedures by means of block randomization.     

Model-based design of low-temperature carbon nanotube synthesis via catalytic oxidation for supercapacitor application

Novel electrochemical double layer capacitors with carbon nanotube (CNT) electrode, often referred to as supercapacitors, have a potential to bridge a power and energy gap between traditional dielectric capacitors and chemical batteries. However, their future is uncertain because current fabrication technologies involve difficult-to-control post-growth manipulations of CNTs. This paper addresses this problem by introducing model-based design of low-temperature CNT synthesis that is suitable for in-situ fabrication of CNT-based supercapacitor electrode. The insight to the surface kinetics during low-temperature CNT synthesis via catalytic oxidation was obtained via coupled Molecular Dynamics and Quantum Semiempirical Hamiltonian simulations. It was determined that the presence of oxygen on the surface of catalyst increases, by several times, the time necessary for the decomposition of hydrocarbons as well as shifts the reaction zone from the surface of catalyst to the catalyst underlayer. Theoretical trends were confirmed by CNT growth experiments. A contact between conducting CNTs and zinc oxide binding layer was analyzed in detail since its properties strongly affect the performance of CNT electrode. It was demonstrated that the formed CNT-zinc oxide interface was free from unbonded oxygen atoms and/or clusters of zinc atoms and was weakly affected by defects in CNTs.     

Catalysis stability enhancement of Fe/Co dual-atom site via phosphorus coordination for proton exchange membrane fuel cell

Non-precious metal catalysts(NPMCs)are promising low-cost alternatives of Pt/C for oxygen reduction reaction(ORR),which however suffer from serious stability ch...