Effects of emulsifier on the bonding performance and freeze–thaw stability of starch-based wood adhesive

In this study, different emulsifiers were used to improve the bonding performance and freeze–thaw stability of renewable starch-based wood adhesive. The improved bonding performance and freeze–thaw stability were supported by the enhanced shear strength, grafted parameters, and viscosity stability after repeated freeze–thaw cycling. ζ-Potential determination, differential scanning calorimetry and pulsed nuclear magnetic resonance analysis indicated that the emulsifiers improve the grafting of vinyl acetate monomers into the starch bonds via free radical vinyl polymerization and hinder the aggregation of starch molecules. Among the emulsifiers tested, sodium dodecyl sulfate showed the highest improvement in the bonding performance and freeze–thaw stability of starch-based wood adhesives.     

Synthesis of a novel series of polymerizable surfactants and application in emulsion polymerization

A series of polymerization surfactants (surfmers) was synthesized, whose structures combined the characteristics of polyoxyethylene as nonionic group and quaternary ammonium a as cationic group. The structures of the product were confirmed by MS, and the content of cationic‐activity matter was determined by two‐phase titration. The surfmers were then used with constant addition profiles in semicontinuous polymerization of vinyl acetate–butyl acrylate–Veova 10–hexafluorobutyl methacrylate, and the polydispersity indexes (PDI) were lower than 0.1. The particle size, amount of coagulum, and stability against electrolyte and freeze/thaw were evaluated. As a reference, an unreactive surfactant cetyl trimethyl ammonium bromide (CTAB) was also used for the polymerization. Compared to CTAB, the surfmers behaved much better. Not only stabilities to electrolyte and water resistance were improved, but also freeze/thaw stability got a superior performance. Copyright © 2008 John Wiley & Sons, Ltd.     

Chromatographic method for the simultaneous quantification of dapsone and clofazimine in nanoformulations

The low bioavailability and nonspecific distribution of dapsone and clofazimine, commonly applied in combination for the treatment of leprosy, can produce toxic effects. Nanotechnological approaches enhance the delivery of these drugs. Therefore, a high‐performance liquid chromatography method was developed for the simultaneous determination of dapsone and clofazimine loaded in nanoformulations for quality control purposes. Chromatographic separation was achieved on a reversed‐phase Kinetex core‐shell C18 column, followed by spectrophotometric detection at 280 nm. Considering the different physicochemical properties of dapsone and clofazimine, elution was performed in gradient mode using an aqueous acetate buffer (50 mmol/L, pH 4.8) and an increasing acetonitrile content from 27 to 63% v/v at a flow rate of 1.0 mL/min with retention times of 6.2 and 14.0 min, respectively. The method was validated according to the European Medicines Agency guideline and it was found to be specific, accurate (99.6–114.0%), and precise for intra‐ (RSD ≤ 1.8%) and interday assays (RSD ≤ 12.5%). Both drugs showed stability after 24 h at room temperature and over three freeze–thaw cycles with recoveries ≥86.2%. Low temperature (4°C) in the autosampler caused the precipitation of clofazimine and must be avoided. The validated method was successfully applied in the quantification of both drugs in nanoformulations.     

Effect of Cactus (Opuntia ficus-indica) and Acacia (Acacia seyal) Gums on the Pasting,Thermal, Textural,and Rheological Properties of Corn,Sweet Potato,and Turkish Bean Starches

This study was planned to explore the locally available natural sources of gum hydrocolloids as a natural modifier of different starch properties. Corn (CS), sweet potato (SPS), and Turkish bean (TBS) starches were mixed with locally extracted native or acetylated cactus (CG) and acacia (AG) gums at 2 and 5% replacement levels. The binary mixtures (starch–gums) were prepared in water, freeze dried, ground to powder, and stored airtight. A rapid viscoanalyzer (RVA), differential scanning calorimeter (DSC), texture analyzer, and dynamic rheometer were used to explore their pasting, thermal, textural, and rheological properties. The presence of acetylated AG or CG increased the final viscosity (FV) in all three starches when compared to starch pastes containing native gums. Plain SPS dispersion had a higher pasting temperature (PT) than CS and TBS. The addition of AG or CG increased the PT of CS, SPS, and TBS. The thermograms revealed the overall enthalpy change of the starch and gum blends: TBS > SPS > CS. The peak temperature (T_p) of starches increased with increasing gum concentration from 2 to 5% for both AG and CG native and modified gums. When compared to the control gels, the addition of 2% CG, either native or modified, reduced the syneresis of starch gels. However, further addition (5% CG) increased the gels’ syneresis. Furthermore, the syneresis for the first cycle on the fourth day was higher than the second cycle on the eighth day for all starches. The addition of native and acetylated CG reduced the hardness of starch gels at all concentrations tested. All of the starch dispersions had higher G′ than G″ values, indicating that they were more elastic and less viscous with or without the gums. The apparent viscosity of all starch gels decreased as shear was increased, with profiles indicating time-dependent thixotropic behavior. All of the starch gels, with or without gums, showed a non-Newtonian shear thinning trend in the shear stress vs. shear rate graphs. The addition of acetylated CG gum to CS resulted in a higher activation energy (Ea) than the native counterparts and the control. More specifically, starch gels with a higher gum concentration (5%) provided greater Ea than their native counterparts.     

Development and validation of a sensitive assay for the quantification of imatinib using LC/LC‐MS/MS in human whole blood and cell culture

We developed and validated a semi‐automated LC/LC‐MS/MS assay for the quantification of imatinib in human whole blood and leukemia cells. After protein precipitation, samples were injected into the HPLC system and trapped onto the enrichment column (flow 5 mL/min); extracts were back‐flushed onto the analytical column. Ion transitions [M + H]⁺ of imatinib (m/z = 494.3 → 394.3) and its internal standard trazodone (372.5 → 176.3) were monitored. The range of reliable response was 0.03–75 ng/mL. The inter‐day precisions were: 8.4% (0.03 ng/mL), 7.2% (0.1 ng/mL), 6.5% (1 ng/mL), 8.2% (10 ng/mL) and 4.3% (75 ng/mL) with no interference from ion suppression. Autosampler stability was 24 hs and samples were stable over three freeze–thaw cycles. This semi‐automated method is simple with only one manual step, uses a commercially available internal standard, and has proven to be robust in larger studies. Copyright © 2009 John Wiley & Sons, Ltd.     

Conformational contribution to the heat capacity of the starch and water system

The heat capacities of starch and starch—water have been measured with adiabatic calorimetry and standard differential scanning calorimetry and are reported from 8 to 490 K. The amorphous starch containing 11–26 wt % (53–76 mol %) water shows a partial glass transition decreasing from 372 to 270 K, respectively. Even the dry amorphous starch gradually increases in heat capacity above 270 K beyond that set by the vibrational density of states. This gradual increase in the heat capacity is identified as part of the glass transition of dry starch that is, however, not completed at the decomposition temperature. The heat capacities of the glassy, dry starch are linked to an approximate group vibrational spectrum with 44 degrees of freedom. The Tarasov equation is used to estimate the heat capacity contribution due to skeletal vibrations with the parameters Θ₁ = 795.5 K, Θ₂ = 159 K, and Θ₃ = 58 K for 19 degrees of freedom. The calculated and experimental heat capacities agree better than ±3% between 8 and 250 K. Similarly, the vibrational heat capacity has been estimated for glassy water by being linked to an approximate group vibrational spectrum and the Tarasov equation (Θ₁ = 1105.5 K and Θ₃ = 72.4 K, with 6 degrees of freedom). Below the glass transition, the heat capacity of the solid starch—water system has been estimated from the appropriate sum of its components and also from a direct fitting to skeletal vibrations. Above the glass transition, the differences are interpreted as contributions of different conformational heat capacities from chains of the carbohydrates interacting with water. The conformational parts are estimated from the experimental heat capacities of dry starch and starch—water, decreased by the vibrational and external contributions to the heat capacity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 3038–3054, 2001     

Formulation and molecular docking simulation study of luliconazole nanosuspension–based nanogel for transdermal drug delivery using modified polymer

The purpose of study was to formulate nanosuspension-based nanogel of luliconazole (LLZ) for transdermal delivery to enhance its skin retention and effectiveness using modified starch ester. Nanosuspensions show promising results with size of 369.1–745.4 nm having PDI 0.193–0.344 and zeta potential 22–45 mV. These nanosuspensions form micelles and hydrophobic core of it provides the reservoir for LLZ with better drug loading and binding interaction. Drug loading was confirmed by percent drug entrapment efficiency (PDEE) and PDI. Molecular docking simulation (MDS) provides detail insight of LLZ polymer complexation at hydrophobic cavity of micelles and revealed that there was binding between drug and polymer in aqueous milieu having interaction energy ranges from ?7.1 to ?6.0 kcal/mol. Nanosuspensions so made were incorporated into gel by using Carbopol 934 ® and tested for % drug content, spreadability, pH, and viscosity with ranges of 101.62–97.71, 28.94–34.38 (gcm/s), 6.91–7.21, and 4802.62–9461.83 (cp), respectively. Nanogel also evaluated for stability and skin permeation study using human cadaver skin (HCS). In vitro skin permeation study indicated that the amount of LLZ permeated through skin from nanogel (71.042–83.818 μgcm ?2) was higher than standard cream (70.085 μgcm ?2). Nanogel increased the accumulation of LLZ in HCS ~3 times than standard cream. The transdermal flux was greater for standard cream (123.79 μgcm ?2), whereas smaller for nanogel (50.394–82.743 μgcm ?2) due to skin retention. Nanosuspension-based gel are able to especially favor LLZ accumulation into skin, provide better drug loading, improve stability, and efficacy. Thus, targeting older antibiotics such as LLZ and formulating into nanosystem utilized to expand its usefulness to physicians to treat illnesses caused by resistant fungal strains.     

Effect of Molar Substitution on the Properties of γ-Hydroxypropyl Starch

A new type of hydroxyalkyl starch, γ-hydroxypropyl starch (γ-HPS), was prepared by etherification of alkali-activated starch with 3-chloropropanol. The reaction efficiency, morphological change, thermodynamic and apparent viscosity properties, and other physicochemical characteristics were described. The molar substitution (MS) of modified whole starch was determined to be 0.008, 0.017, 0.053, 0.106, and 0.178, with a ratio of 5%, 15%, 25%, 35%, and 45% 3-chloropropanol to starch (v/w), respectively. Compared to native starch, the granular size and shape and the X-ray diffraction pattern of γ-HPS are not very different. For low-substituted γ-HPS, the implications may be less evident. Thermal stability measurements by means of thermogravimetric analyses and differential scanning calorimetry (TGA-DSC) proved that thermal stability was reduced and water retaining capacity was increased after hydroxypropylation. Furthermore, the findings also showed that the solubility, light transmittance, and retrogradation of γ-HPS pastes could be improved by etherification. The greater the MS of the γ-HPS, the more its freeze–thaw stability and acid resistivity increased. In this study, we provide relevant information for the application of γ-HPS in food and non-food industries.     

丙烯酸酯无皂乳液稳定性研究

研究了亲水性单体ＡＡ和引发剂Ｋ２Ｓ２Ｏ８用量对三元共聚物（ＭＭＡ／ＢＡ／ＡＡ）无皂乳液（ｐＨ＝８）的电解质稳定性、冻融稳定性和机械稳定性的影响。当乳液电解质稳定性最好时存在ＡＡ和Ｋ２Ｓ２Ｏ８用量最佳值,而乳液的机械稳定性则随ＡＡ和Ｋ２Ｓ２Ｏ８用量增大而迅速提高。乳液中加入丙酮可以改善其稳定性。     

Styrenic surfmer in emulsion copolymerization of acrylic monomers. II. Copolymerization and film properties

Polymerizable styrenic surfactants (surfmers) and nonreactive analogs, have been applied in emulsion copolymerization of acrylic monomers in a seeded semibatch process. Stable core-shell latexes with low levels of coagulum and controlled particle size have been obtained; some of them, with either steric or electrosteric stabilization, display excellent stability to electrolytes, freeze–thaw cycles, and shear flocculation. In addition, the reactive surfactants lead to films with superior performance due to reduced migration of surfactant to the surface (contact angle measurements) and dimensional stability when the films are dipped in water, as well as less water uptake. Some differences also appear in particle morphologies. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4205–4217, 1999     

Development,validation, and implementation of an UHPLC–MS/MS method for the quantitation of furosemide in infant urine samples

Furosemide is a diuretic drug used to increase urine flow in order to reduce the amount of salt and water in the body. It is commonly utilized to treat preterm infants with chronic lung disease of prematurity. There is a need for a simple and reliable quantitation of furosemide in human urine. We have developed and validated an ultra-high performance liquid chromatography–tandem mass spectrometry method for furosemide quantitation in human urine with an assay range of 0.100–50.0 μg/ml. Sample preparation involved solid-phase extraction with 10 μl of urine. Intra-day accuracies and precisions for the quality control samples were 94.5–106 and 1.86–10.2%, respectively, while inter-day accuracies and precision were 99.2–102 and 3.38–7.41%, respectively. Recovery for furosemide had an average of 23.8%, with an average matrix effect of 101%. Furosemide was stable in human urine under the assay conditions. Stability for furosemide was shown at 1 week (room temperature, 4, −20 and −78°C), 6 months (−78°C), and through three freeze–thaw cycles. This robust assay demonstrates accurate and precise quantitation of furosemide in a small volume (10 μl) of human urine. It is currently being implemented in an ongoing pediatric clinical study.     

Interactions between flaxseed gums and WPI-stabilized emulsion droplets assessed in situ using diffusing wave spectroscopy

Diffusing wave spectroscopy (DWS) was used to investigate the behavior of flaxseed gums when added to WPI-stabilized emulsions. The effect of different concentrations (0–0.33% (w/v)) of flaxseed gum, derived from two seed varieties, namely Emerson and McDuff, was studied at acidic and neutral pH. At pH 7.0 and low gum concentrations the dynamic and spatial characteristics of the system remained unchanged. While at gum concentrations from 0.075% to 0.20% a rapid phase separation was observed, at higher concentrations phase separation was retarded because of the increased background viscosity slowing down the mobility of the emulsion droplets. At pH 3.5, the difference in overall electrical charge between the gum (negative) and the protein on the emulsion surface (positive) led to electrostatic interactions. While at low concentration of flaxseed gum the general characteristics of the emulsions were not significantly different, at intermediate concentrations, bridging flocculation occurred. When sufficient flaxseed gum was present, the emulsion droplets mobility was arrested in a gel-like state. In spite of the compositional differences in the ratio of acidic and neutral fraction between the two polysaccharides extracted from different seed varieties, at both values of pH the behavior of the emulsions after addition of the polysaccharide was comparable.     

Physical stability of oil-in-water emulsions in the presence of gamma irradiated gum tragacanth

Gum tragacanth (GT) exuding from an Iranian Astragalus species was γ-irradiated at 0, 0.75, 1.5, 3, 5, 7, and 10?kGy and used to stabilize a model oil-in-water emulsion system. Stability and physicochemical properties of emulsion samples were investigated with respect to the effect of irradiation treatment on functional properties of gum tragacanth. Particle size distribution, interfacial tension, zeta potential, steady shear, and oscillatory rheological measurements were used to characterize and evaluate the emulsion samples and obtain more information about the possible stability mechanism. Emulsions were prepared by homogenizing 10% w/w sun flower oil with 90% w/w aqueous gum dispersions and stored quiescently at 25°C for 120 days. The results indicated that using 1.5?kGy irradiated GT was more effective in providing optimum values of apparent viscosity, number mean diameter, electrosteric repulsion, and structure strength for getting the maximum emulsion stability. GT significantly reduced the interfacial tension of the oil and water system, but no significant differences were observed among all irradiation treated and non-irradiated samples. This study revealed that GT acts as a bifunctional emulsifier and irradiation treatment has a great positive influence on its ability to reduce droplets’ collision frequency and stabilize the oil-in-water emulsion.     

Two quality and stability indicating imaged CIEF methods for mRNA vaccines

Two imaged capillary isoelectric focusing methods were developed to provide insight into the quality and stability of messenger ribonucleic acid (mRNA) vaccines, specifically, mRNA encapsulated in lipid nanoparticles (LNPs). A variety of stressed and lipid composition-modified samples were measured and detected by their UV absorption. The results were supported by the data of an encapsulation assay and particle sizing. One method, using 9 M urea as an additive, shows two broad and jagged peaks in which the peak shape offers detailed information. The summed peak area of both peaks showed RSDs from 2% to 8% when one batch was measured in triplicate and apparently depends on the size of the LNPs. In the second method, a combination of 5.5 M urea and 2 M N-ethylurea was used. This method is characterized by a high repeatability of the isoelectric point (pI, <0.5%). The repeatable peak area (RSD of 2%–7%) correlates linearly with the mRNA content, which also applies to the first method, and added stress is evident by the change in pI and peak area. Furthermore, experiments with the addition of a fluorescent dye were performed (fluorescence detection), which tremendously increased the sensitivity of the methods. Both methods can be used to characterize the stability of mRNA-loaded LNPs, for example, when investigating various storage times at different temperatures and freeze–thaw cycles, as well as the ability of the methods to distinguish lipid compositions and measure batch-to-batch variability.     

Investigation regarding the effect of viscosity modifying admixtures upon the Portland cement hydration using thermal analysis

The effect of 13 viscosity modifying admixtures (VMA) on the Portland cement hydration was studied in this paper. In this purpose, thermal analyses (DTA and TG) were performed after 1, 7 and 28 days of hydration on cement pastes containing 0.01–0.5 % from the following VMA: diutan gum, welan gum, polygalactomannane ether, natural cellulose fibres, modified polysaccharide, polyacrylamide, high-molecular mass synthetic copolymer, hydroxypropyl starch and a chemically modified starch. It was noticed that the proportion of Ca(OH)₂ from the samples containing polygalactomannane ether and modified polysaccharide was smaller than in the reference sample, which proved their effect of cement hydration delay. For the other VMA, this effect was not detected, on the contrary, the amount of Ca(OH)₂ was higher than in the reference sample.     

Effect of high-dose irradiation and autoclave treatment on microbial safety and quality of ready-to-eat Bulgogi sauce

In Korea, commercialized sauce for ready-to-eat (RTE) Bulgogi is usually manufactured using heat treatment to ensure that it has a long shelf-life. However, heat treatment may adversely affect the taste and flavor of the sauce, thus, the development of suitable sterilizing methods for RTE sauces is necessary to preserve the quality of the sauce during long storage periods. In this study, total bacterial growth, the viscosity, and the sensory properties of Bulgogi sauce were compared between sterilization with gamma irradiation (0–40 kGy) and autoclave treatment during storage at 35 °C for 90 days. No bacterial growth was observed following irradiation at more than 10 kGy or after autoclave treatment. However, the viscosity and sensory properties of samples gamma-irradiated at above 10 kGy or autoclave-treated were significantly changed, even though autoclave treatment induced a burnt taste and flavor. Therefore, a gamma irradiation of 10 kGy was effective to prepare ready-to-eat Bulgogi sauce with microbial safety and original sensory qualities.     

Development and validation of a rapid and sensitive HPLC method for the quantification of 5‐fluorocytosine and its metabolites

To study the intracellular metabolism of the prodrug 5‐fluorocytosine (5FC), we developed a novel reverse‐phase high‐performance liquid chromatography method to simultaneously detect 5FC and its four major anabolic metabolites: 5‐fluorouracil, 5‐fluorouridine, 5‐fluorouridine‐monophosphate and 5‐fluoro‐2′deoxyuridine‐5′‐monophosphate. Separation of each compound was accomplished under isocratic conditions using a C₁₈ column and mobile phase of formic acid–water (1 : 99 v/v). The method was validated for both accuracy and reproducibility in cell culture media. Additionally, metabolites were assessed for stability at ambient temperatures and following freeze–thaw cycles. Calibration curves were linear over a range of 1–200 μg/mL. Limit of quantification for four of the five compounds was 1 μg/mL in cell culture media (RSD < 11%). This method was successfully used to monitor intracellular conversion of 5FC to its metabolic products over a 24h period. Copyright © 2009 John Wiley & Sons, Ltd.     

Impact of Adding Polysaccharides on the Stability of Egg Yolk/Fish Oil Emulsions under Accelerated Shelf-Life Conditions

Polysaccharides can form interfacial complexes with proteins to form emulsions with enhanced stability. We assessed the effect of adding gum guar or gum arabic to egg yolk/fish oil emulsions. The emulsions were produced using simple or high-pressure homogenization, stored for up to 10 days at 45 °C, and characterized for their particle size and distribution, viscosity, encapsulation efficiency, oxidative stability, and cytotoxicity. Emulsions containing gum guar and/or triglycerides had the highest viscosity. There was no significant difference in the encapsulation efficiency of emulsions regardless of the polysaccharide used. However, emulsions containing gum arabic displayed a bridging flocculation effect, resulting in less stability over time compared to those using gum guar. Emulsions produced using high-pressure homogenization displayed a narrower size distribution and higher stability. The formation of peroxides and propanal was lower in emulsions containing gum guar and was attributed to the surface oil. No significant toxicity toward Caco-2 cells was found from the emulsions over time. On the other hand, after 10 days of storage, nonencapsulated fish oil reduced the cell viability to about 80%. The results showed that gum guar can increase the particle stability of egg yolk/fish oil emulsions and decrease the oxidation rate of omega-3 fatty acids.     

Characterization of a β-glucanase produced by Rhizopus microsporus var. microsporus, and its potential for application in the brewing industry

Background  

In the barley malting process, partial hydrolysis of β-glucans begins with seed germination. However, the endogenous 1,3-1,4-β-glucanases are heat inactivated, and the remaining high molecular weight β-glucans may cause severe problems such as increased brewer mash viscosity and turbidity. Increased viscosity impairs pumping and filtration, resulting in lower efficiency, reduced yields of extracts, and lower filtration rates, as well as the appearance of gelatinous precipitates in the finished beer. Therefore, the use of exogenous β-glucanases to reduce the β-glucans already present in the malt barley is highly desirable.     

Hydroalcoholic Extract of Encholirium spectabile Mart. (Bromeliaceae) in O/W Emulsions as an Additive against the UVB Radiation

The use of sunscreen is one of the photoprotection measures most used by the population, so these products must offer broad-spectrum protection against UVA and UVB radiation. Encholirium spectabile, popularly known as “macambira-de-flecha,” is a species characterized by its rocky outcrops and found in the Caatinga. This biome is known for extreme droughts and dry periods, and for this reason, its vegetation needed to develop resistance mechanisms. The aim of this work was to evaluate the use of E. spectabile incorporated in O/W emulsion as a potential photoprotective agent and their antioxidant activity. Four chemical constituents (ferulic acid, caffeic acid, p-coumaric acid and apigenin) were identified by HPLC-DAD analysis, and emulsions containing different concentrations (1%, 2.5% and 5%) of the extract without and with the addition of chemical filters (octyl methoxycinnamate and benzophenone-3) were prepared and submitted to the test of preliminary stability. The Q formulation demonstrated little variation in the preliminary stability test and was selected for estimated your protection against UVB and determination of in vitro protection factor UVA. The formulations remained stable during the freeze–thaw cycle; the extract despite maintaining the UVA-PF and decreasing the wavelength showed an increase in FPS from 14.4 (control) to 18.8 (control+ Es-HA80).