Response Surface Modeling of Processing Parameters for the Preparation of Phytosterol Nanodispersions Using an Emulsification–Evaporation Technique

The purpose of this study was to optimize the production parameters for water-soluble phytosterol nanodispersions. Response surface methodology (RSM) was employed to model and optimize three of the processing parameters: mixing time (t) by conventional homogenizer (1–20 min), mixing speed (v) by conventional homogenizer (1,000–9,000 rpm) and homogenization pressure (P) by high-pressure homogenizer (0.1–80 MPa). All responses [i.e., mean particle size (PS), polydispersity index (PDI) and phytosterols concentration (Phyto, mg/l)] fitted well to a reduced quadratic model by multiple regressions after manual elimination. For PS, PDI and Phyto, the coefficients of determination (R ²) were 0.9902, 0.9065 and 0.8878, respectively. The optimized processing parameters were 15.25 min mixing time, 7,000 rpm mixing speed and homogenization pressure 42.4 MPa. In the produced nanodispersions, the corresponding responses for the optimized preparation conditions were a PS of 52 nm, PDI of 0.3390 and a Phyto of 336 mg/l.     

Process Optimization,Physical Properties,and Environmental Stability of an α-Tocopherol Nanocapsule Preparation Using Complex Coacervation Method and Full Factorial Design

α-Tocopherol (α-Toc) has valuable biological activity, but its activity is limited when exposed to environmental factors. Nanocapsules can be used to overcome this problem. Using nanocapsules in the range of 100–200 nm is more beneficial. A 2⁴ full factorial design was carried out to optimize the size of nanocapsules using the complex coacervation method. The four factors were the amount of the wall material, the ratio of core material to wall material, the pH of the solution, and the speed of the homogenizer. The smallest nanocapsules (176 nm) were obtained at a wall content (gelatine and pectin) of 0.8 mg, a percentage of core material (α-Toc) to wall material of 20%, a pH = 4.5, and a homogenizer speed of 12,000 rpm. The encapsulation efficiency was 90.6 ± 1.1%, and the encapsulation yield was 83.4 ± 1.6%. Assessment of the stability of α-Toc after 1 month showed that encapsulation could improve its stability in the presence of three influential factors: humidity, light, and temperature.     

Optimization of the Spray Drying Operating Parameters—A Quick Trial-and-Error Method

This short communication reports an optimization approach to effectively determine suitable spray drying operating parameters for a pilot-scale dryer. The proposed optimization approach is essential, as pilot-scale investigations and medium-scale contract productions often involve usage of standard spray dryer units which is not specifically designed for the feed material used. This optimization approach was developed based on past studies on the effect and relationship of the many spray drying operating parameters and highlights two factors which has to be solved (or considered) chronologically: dripping problem, followed by product caking problem. Based on this proposed approach, an algorithm was developed in a case study to optimize an available spray dryer for our future experimental study on wall deposition. In this case, the operating parameters were determined under minimal experimental runs. This proposed optimization approach will be a useful tool for operators and experimenters utilizing spray dryers of similar type, particularly in exploring new feed materials. Depending on the optimization objectives and experimental limitations, different algorithms can be developed. Apart from that, interesting deposition pattern was also observed in the case study. This short communication also reported on the design of an internal rig for further studies on wall deposition.     

Physico-Chemical Features and Catalytic Activity of Sulfated Zirconia Prepared by Sol–Gel Method. The Role of the Solvent Evaporation Step

ZrO₂–SO₄ powders have been prepared by following a single-step sol–gel preparative route using zirconium propoxide as the starting compound. Sulfuric acid was employed both as the sulfating agent and as the catalyst of the polycondensation reaction in the gel formation. Two different series of dried precursors were obtained by either evaporating the solvent in an oven at 100°C (xerogels) or in supercritical conditions (aerogels). All the samples were calcined at three temperatures (470, 550, and 630°C) for the same time length (5 h). The powders were characterized for phase composition–crystallinity, surface area–porosity, sulfur content and surface state (XPS). The catalytic activity of the calcined samples was tested in the isomerization of n-butane in a continuous system at 150°C in absence of H₂ and 250°C in presence of H₂. The role played by the conditions of the solvent elimination, at the end of the sol–gel reaction, in affecting the physico-chemical and catalytic properties of the powders is discussed.     

Optimization of temperature swing strategy for selective cooling crystallization of α-form l-glutamic acid crystals

l-glutamic acid can be crystallized as metastable α-form and stable β-form crystal. The α-form is desired because of its prismatic shape. Production of α-form of l-glutamic acid by cooling crystallization is not well-defined and α-form solid is commercially not available. In this study, an optimal cooling strategy to selectively produce large and narrowly distributed α-crystals is found by modeling and optimizing the crystallization and polymorphic transformation of l-glutamic acid. The optimal temperature profile is found to be cooling-heating-cooling concept where short nucleation period is followed by growth period in metastable zone. The obtained α-form of L-glutamic acid by optimal strategy had improved mean size, distribution, and purity compared to constant cooling.     

Optimization of nano spray drying parameters for production of α-amylase nanopowder for biotheraputic applications using factorial design

Abstract

This study was designed to optimize the effect of operating conditions and formulation parameters using various additives to develop α-amylase nanoparticles. α-Amylase was chosen due to its importance in the substantial number of industrial processing with emphasis on pharmaceutical industry. Factorial statistical design was adopted to effectively optimize the size, yield value, residual enzyme activity, and morphology of α-amylase nanoparticles using Nano Spray Dryer BÜCHI B-90. The physicochemical characterization of the prepared nanopowder was carried out using zetasizer and scanning electron microscopy (SEM) and enzyme activity assay. Results showed that the type of additive and mesh size significantly influenced the particles size and yield value. SEM images showed three different structure patterns where particle morphology was influenced by Tween^® 80 or sucrose at low concentration (0.05%). Optimized spherical nanoparticles (600?nm) was obtained using 7 µm mesh cap size, sucrose (0.15%), 95% yield value, drying flow rate (100?L/min), and inlet temperature of 80?°C. Higher storage stability was detected for enzyme spray-dried using larger cap size. It was concluded that nano spray drying of aqueous enzyme solution under determined operating conditions produced stable α-amylase powders. This would extend the application of the enzyme in a variety of pharmaceutical products.     

Tissue Distribution of α- and γ-Tocotrienol and γ-Tocopherol in Rats and Interference with Their Accumulation by α-Tocopherol

The aim of this study was to evaluate tissue distribution of vitamin E isoforms such as α- and γ-tocotrienol and γ-tocopherol and interference with their tissue accumulation by α-tocopherol. Rats were fed a diet containing a tocotrienol mixture or γ-tocopherol with or without α-tocopherol, or were administered by gavage an emulsion containing tocotrienol mixture or γ-tocopherol with or without α-tocopherol. There were high levels of α-tocotrienol in the adipose tissue and adrenal gland, γ-tocotrienol in the adipose tissue, and γ-tocopherol in the adrenal gland of rats fed tocotrienol mixture or γ-tocopherol for 7 weeks. Dietary α-tocopherol decreased the α-tocotrienol and γ-tocopherol but not γ-tocotrienol concentrations in tissues. In the oral administration study, both tocopherol and tocotrienol quickly accumulated in the adrenal gland; however, their accumulation in adipose tissue was slow. In contrast to the dietary intake, α-tocopherol, which has the highest affinity for α-tocopherol transfer protein (αTTP), inhibited uptake of γ-tocotrienol to tissues including adipose tissue after oral administration, suggesting that the affinities of tocopherol and tocotrienol for αTTP in the liver were the critical determinants of their uptake to peripheral tissues. Vitamin E deficiency for 4 weeks depleted tocopherol and tocotrienol stores in the liver but not in adipose tissue. These results indicate that dietary vitamin E slowly accumulates in adipose tissue but the levels are kept without degradation. The property of adipose tissue as vitamin E store causes adipose tissue-specific accumulation of dietary tocotrienol.     

Solvent effect on the equilibrium polymerization of α-methylstyrene

The Flory-Huggins interaction parameter χ has been determined from static vapour-pressure measurements for four binary mixtures: α-methylstyrene in p-dioxane or cyclohexane, and poly(α-methylstyrene) in p-dioxane or cyclohexane. For the first system, measurements were carried out at 25 and 40°C, yielding values between 0.12 and 0.18 for χ. The second one was investigated at 30, 35 and 40°C leading to χ values between 0.50 and 0.58. The values at 40°C for the third system lie between 0.40 and 0.46 when the polymer volume fraction varies from 0.10 to 0.35. The last system, also at 40°C, has χ values of 0.49 and 0.60 for polymer volume fraction of 0.10 and 0.27, respectively. These parameters were used to compute the equilibrium compositions of monomer and polymer, at any solvent concentration, for the polymerization of α-methylstyrene in different solvents.     

A Modified Method for Determining Tannin–Protein Precipitation Capacity Using Accelerated Solvent Extraction (ASE) and Microplate Gel Filtration

The protein precipitation assay used by Robbins et al., (1987) Ecology 68:98–107 has been shown to predict successfully the reduction in protein availability to some ruminants due to tannins. The procedure, however, is expensive and laborious, which limits its utility, especially for quantitative ecological or nutritional applications where large numbers of assays may be required. We have modified the method to decrease its cost and increase laboratory efficiency by: (1) automating the extraction by using Accelerated Solvent Extraction (ASE); and (2) by scaling and automating the precipitation reaction, chromatography, and spectrometry with microplate gel filtration and an automated UV–VIS microplate spectrometer. ASE extraction is shown to be as effective at extracting tannins as the hot methanol technique. Additionally, the microplate assay is sensitive and precise. We show that the results from the new technique correspond in a nearly 1:1 relationship to the results of the previous technique. Hence, this method could reliably replace the older method with no loss in relevance to herbivore protein digestion. Moreover, the ASE extraction technique should be applicable to other tannin–protein precipitation assays and possibly other phenolic assays.     

Intensification of Freeze-Drying Rate of Bacillus subtilis MTCC 2396 Using Tungsten Halogen Radiation: Optimization of Moisture Content and α-Amylase Activity

A novel freeze-drying protocol has been explored to render fast and cost-effective freeze drying of hyperamylase producing Bacillus subtilis MTCC2396 employing a tungsten halogen lamp radiator (THLR) as a heat source. Response surface methodology assessed the maximum reduction in moisture content (96.07%) and minimum reduction in α-amylase (EC 3.2.1.1) activity (1.02%) in 4 h drying time at 42.5°C radiation temperature. α-amylase activity (0.046 U) and final moisture content (3.93%) of the optimally freeze-dried bacterial strain appeared satisfactory. The freeze-drying time using THLR (4 h) is remarkably lower compared to that under a conventional conductive plate heater (CPH) (10 h) at otherwise identical conditions. The higher effective moisture diffusivity of 0.0052 to 0.0078 m ²/s under THLR compared to 0.00084 to 0.0015 m ²/s under CPH (corresponding to 20–50°C) advocated the superiority of the THLR heating protocol. The higher efficacy of THLR was also evidenced through lower activation energy (8.42 kJ/mol) of moisture diffusion compared to that (12.051 kJ/mol) of CPH. The optimally freeze-dried bacteria demonstrated the same growth rate in addition to exhibiting excellent retention of bioremedial (Hg²⁺ removal) activity to that of the control.     

Kinetic Study of the Prooxidant Effect of α-Tocopherol. Hydrogen Abstraction from Lipids by α-Tocopheroxyl Radical

A kinetic study of the prooxidant effect of α-tocopherol was performed. The rates of allylic hydrogen abstraction from various unsaturated fatty acid esters (ethyl stearate 1, ethyl oleate 2, ethyl linoleate 3, ethyl linolenate 4, and ethyl arachidonate 5) by α-tocopheroxyl radical in toluene were determined, using a double-mixing stopped-flow spectrophotometer. The second-order rate constants (k _p) obtained are <1 × 10⁻² M⁻¹ s⁻¹ for 1, 1.90 × 10⁻² M⁻¹ s⁻¹ for 2, 8.33 × 10⁻² M⁻¹ s⁻¹ for 3, 1.92 × 10⁻¹ M⁻¹ s⁻¹ for 4, and 2.43 × 10⁻¹ M⁻¹ s⁻¹ for 5 at 25.0 °C. Fatty acid esters 3, 4, and 5 contain two, four, and six –CH₂– hydrogen atoms activated by two π-electron systems (–C=C–CH₂–C=C–). On the other hand, fatty acid ester 2 has four –CH₂– hydrogen atoms activated by a single π-electron system (–CH₂–C=C–CH₂–). Thus, the rate constants, k _abstr/H, given on an available hydrogen basis are k _p/4 = 4.75 × 10⁻³ M⁻¹ s⁻¹ for 2, k _p/2 = 4.16 × 10⁻² M⁻¹ s⁻¹ for 3, k _p/4 = 4.79 × 10⁻² M⁻¹ s⁻¹ for 4, and k _p/6 = 4.05 × 10⁻² M⁻¹ s⁻¹ for 5. The k _abstr/H values obtained for 3, 4, and 5 are similar to each other, and are by about one order of magnitude higher than that for 2. From these results, it is suggested that the prooxidant effect of α-tocopherol in edible oils, fats, and low-density lipoproteins may be induced by the above hydrogen abstraction reaction.     

Development of Effective Solvent Modifiers for the Solvent Extraction of Cesium from Alkaline High‐Level Tank Waste

Abstract

A series of novel alkylphenoxy fluorinated alcohols were prepared and investigated for their effectiveness as modifiers in solvents containing calix[4]arene‐bis‐(tert‐octylbenzo)‐crown‐6 for the extraction of cesium from alkaline nitrate media. The structure of the fluorinated portion of the modifier influences the chemical stability, and a modifier that contained a terminal 1,1,2,2‐tetrafluoroethoxy group was found to decompose following long‐term exposure to warm alkaline solutions. However, replacement of the tetrafluoroethoxy group with a 2,2,3,3‐tetrafluoropropoxy group led to a series of modifiers that possessed the alkaline stability required for a solvent extraction process. Within this series of modifiers, the structure of the alkyl substituent (tert‐octyl, tert‐butyl, tert‐amyl, and sec‐butyl) of the alkylphenoxy moiety was found to have a profound impact on the phase behavior of the solvent in liquid–liquid contacting experiments, and hence on the overall suitability of the modifier for a solvent extraction process. The sec‐butyl derivative [1‐(2,2,3,3‐tetrafluoropropoxy)‐3‐(4‐sec‐butylphenoxy)‐2‐propanol] (Cs‐7SB) was found to possess the best overall balance of properties with respect to third phase and coalescence behavior, cleanup following degradation, resistance to solids formation, and cesium distribution behavior. Accordingly, this modifier was selected for use as a component of the solvent employed in the Caustic‐Side Solvent Extraction (CSSX) process designed for the removal of cesium from high‐level nuclear waste (HLW) at the U.S. Department of Energy's (DOE) Savannah River Site. In batch equilibrium experiments, this solvent has also been successfully shown to extract cesium from both simulated and actual solutions generated from caustic leaching of HLW tank sludge stored in tank B‐110 at the DOE's Hanford Site.     

Effects of Phosphatidylcholine on Interaction of α-Tocopherol and β-Carotene in Photosensitized Oxidation of Emulsions

The interaction between α‐tocopherol (500 mg/kg) and β‐carotene (10 mg/kg) during chlorophyll‐photosensitized oxidation of a sunflower oil emulsion was studied in the presence or absence of phosphatidylcholine (PC, 250 mg/kg) by determining peroxide (POV) and conjugated dienoic acid (CDA) values. Chlorophyll, α‐tocopherol, β‐carotene, and PC contents in the emulsion were also monitored. α‐Tocopherol and β‐carotene individually and interactively decreased the POV and CDA values of oil in the emulsion by singlet oxygen quenching. PC decreased the POV and CDA values of oil, however, the values of the emulsion with added α‐tocopherol, β‐carotene, and PC were not significantly different from those of the emulsion with added α‐tocopherol and β‐carotene without PC. Contents of α‐tocopherol did not change during 24‐h oxidation, whereas co‐present PC significantly caused α‐tocopherol and chlorophyll degradation. β‐Carotene and PC contents significantly decreased to 45.5 and 51.3 %, respectively, after 24 h, and α‐tocopherol protected β‐carotene from degradation. The results suggest that PC had no net effects on the interactive antioxidant activity of α‐tocopherol and β‐carotene during chlorophyll‐photosensitized oxidation of the emulsion through free radical generation, chlorophyll degradation, and lessening the potency of α‐tocopherol as a singlet oxygen quencher.     

An Amalgam of Mg-Doped TiO2 Nanoparticles Prepared by Sol–Gel Method for Effective Antimicrobial and Photocatalytic Activity

In this study, undoped and Magnesium doped TiO₂ nanoparticles (Mg-TiO₂ NPs) are successfully synthesized via a simple sol–gel method cost-effectively. The prepared Mg- TiO₂ NPs is characterized by UV–Vis, FTIR, PL, XRD, FESEM, TEM, and EDAX. UV–Visible Spectroscopy showed that an increase in the optical bandgap concerning the concentration of dopant Mg increases. The bandgap values were found to be 3.57–3.54 eV. FTIR spectra shows that the presence of the characteristic stretching and bending vibrational band of Ti–O bonding at 468 cm^?1 and shifts in vibrational bands were observed for Mg-TiO₂ NPs. PL spectra of Mg- TiO₂ NPs at different concentrations exhibit a strong UV emission band. X-ray diffraction confirmed the formation of the tetragonal anatase phase. The average crystallite size of synthesized samples was found to be 22–19 nm. The average crystallite size of Mg- TiO₂ NPs decreases with increasing the concentration of dopant Mg. The FESEM and TEM analysis confirmed that the spherical morphology for both TiO₂ and Mg-TiO₂ NPs. SAED pattern confirms the crystalline nature of prepared samples. EDAX spectra confirm the presence of Ti, O, and Mg and confirm that Mg²⁺ ions are present in the TiO₂ lattices. The prepared samples were investigated against gram-positive and gram-negative bacteria. The prepared samples exhibit potent antibacterial activity against gram-negative bacteria than the gram-positive bacteria. The prepared samples exhibit significant photocatalytic degradation for Methylene blue (MB).

     

Acquisition of Water Solubility Diagrams in Ternary Systems (AOT/Organic Solvent/Alcohol) and Extraction of α-Lactalbumin Using Reverse Micellar Systems

In this study water solubility curves were constructed and calorimetric measurements obtained for reverse micellar systems consisting of an alcohol (isopropanol or butanol), surfactant (AOT) and organic solvent (isooctane or hexane). Also evaluated were the effects of alcohol and solvent type and surfactant concentration on the extraction of the α-lactalbumin (α–la). From the obtained solubility diagrams for ternary systems, it was concluded that isooctane presented the highest water solubility capacity in the center of the micelle systems with hexane, since isooctane has greater molecular volume and greater effect of the surfactant aggregation number. With respect to the alcohols, it was observed that isopropanol and butanol act in the system as a co-surfactant, since they prefer to adsorb at the water/solvent interface. It was also verified that butanol improved water solubility inside the reverse micellar due to its contribution to increase the critical packing parameter. The amount of α-la extracted increased proportionally with the AOT concentration for systems with isooctane and hexane. However, for systems with the latter solvent, the concentration of extracted protein first increases and then decreases. The extraction power of reverse micellar systems with isooctane was influenced by the type of alcohol with butanol showing better results. For systems containing hexane there was no effect of the alcohol added to the system on extraction power of α-lactalbumin.     

Copper-Catalyzed α-Arylation of Sulfoxonium Ylides Using Hypervalent Iodine Compounds

A Cu(I)-catalyzed synthesis of α-arylated sulfoxonium ylides has been achieved from mesitylene-derived diaryliodonium salts and α-carbonyl sulfoxonium ylides. The reaction is believed to proceed via an electrophilic Cu(III)-aryl intermediate that can be trapped upon nucleophilic attack of the sulfoxonium ylide precursor. The reaction was tolerant to both α-keto and α-ester-derived sulfoxonium ylides, to drug-derived ylide motifs and to electronically-diverse arenes, and enabled the direct synthesis of 32 α-aryl-sulfoxonium ylides in 42–85% yield.     

Selective Growth of α-Sexithiophene by Using Silicon Oxides Patterns

A process for fabricating ordered organic films on large area is presented. The process allows growing sexithiophene ultra-thin films at precise locations on patterned Si/SiO(x) substrates by driving the orientation of growth. This process combines the parallel local anodic oxidation of Si/SiO(x) substrates with the selective arrangement of molecular ultra-thin film. The former is used to fabricate silicon oxide arrays of parallel lines of 400 nm in width over an area of 1 cm(2). Selective growth arises from the interplay between kinetic growth parameters and preferential interactions with the patterned surface. The result is an ultra-thin film of organic molecules that is conformal to the features of the fabricated motives.     

Determination of Main Parameters Affecting Ozone Bleaching of Wheat Straw Pulp Using Plackett–Burman Design

Laboratory-scale studies were carried out on ozone bleaching of wheat straw soda pulp. Effects of five variables—pH, consistency, time, temperature, and ozone dose—on three pulp parameters— kappa number, brightness, and viscosity–were determined using Plackett–Burman experimental design. Results showed that for the parameter kappa number of pulp, ozone dose is the most important factor followed by pH and consistency. Pulp parameter viscosity is affected by factor pH, followed by consistency and ozone dose. Brightness of the wheat straw pulp mostly depends on factor ozone dose, followed by pH.     

Autoxidation of Conjugated Linoleic Acid Methyl Ester in the Presence of α-Tocopherol: The Hydroperoxide Pathway

Autoxidation of conjugated linoleic acid (CLA) methyl ester follows at least partly Farmer's hydroperoxide theory. A mechanism for this hydroperoxide pathway has been proposed based on autoxidation of 9-cis,11-trans-CLA methyl ester. This investigation aims at confirming and further clarifying the mechanism by analyzing the hydroperoxides produced from 10-trans,12-cis-CLA methyl ester and by theoretical calculations. Five methyl hydroxyoctadecadienoates were isolated by HPLC and characterized by UV, GC-MS, and 1D- and 2D-NMR techniques. In addition, an HPLC method for the separation of the intact hydroperoxides was developed. The autoxidation of 10-trans,12-cis-CLA methyl ester in the presence of high amount of alpha-tocopherol (20%) was diastereoselective in favor of one geometric isomer, namely Me 9-OOH-10t,12c, and produced new positional isomers 10- and 14-hydroperoxides (Me 10-OOH-11t,13t; Me 14-OOH-10t,12c; and Me 14-OOH-10t,12t). Importantly, one of these new isomers, which was characterized as an intact hydroperoxide, had an unusual cis,trans geometry where the cis double bond is adjacent to the hydroperoxyl-bearing methine carbon. Further insight to the mechanism was provided by calculating the relative energies for different conformations of the precursor lipid, the allylic carbon-hydrogen bond dissociation enthalpies, and the spin distributions on the intermediate pentadienyl radicals. As a result, a better understanding of the isomeric distribution of the product hydroperoxides was achieved and a modified mechanism that accounts for these calculations is presented.