Glycerol Suspension Research Articles

The Role of the Interface of PLA with Thermoplastic Starch in the Nonisothermal Crystallization Behavior of PLA in PLA/Thermoplastic Starch/SiO2 Composites

Corn starch was plasticized by glycerol suspension in a twin-screw extruder, in which the glycerol suspension was the pre-dispersion mixture of glycerol with nano-SiO2. Polylactide (PLA)/thermoplastic starch/SiO2 composites were obtained through melt-blending of PLA with thermoplastic starch/SiO2 in a twin-screw extruder. The nonisothermal crystallization behavior of PLA in the composites was investigated by differential scanning calorimetry. An interface of PLA with thermoplastic starch was proven to exist in the composites, and its interfacial bonding characteristics were analyzed. The interfacial binding energy stemming from PLA with thermoplastic starch exerts a significant influence on the segmental mobility of PLA at the interface. The segmental mobility of PLA is gradually improved by increasing interfacial binding energy, and consequently, the relative crystallinity on the interface exhibits progressive promotion. The Jeziorny model could well describe the primary crystallization of PLA in the composites. The extracted Avrami exponents based on the Jeziorny model indicate that the primary crystallization of PLA follows heterogeneous nucleation and three-dimensional growth. This study has revealed the intrinsic effect of the interfacial segmental mobility on the nonisothermal crystallization behavior of PLA in composites, which is of technological significance for its blow molding.

Altering Terahertz Sound Propagation in a Liquid upon Nanoparticle Immersion.

One of the grand challenges of new generation Condensed Matter physicists is the development of novel devices enabling the control of sound propagation at terahertz frequency. Indeed, phonon excitations in this frequency window are the leading conveyor of heat transfer in insulators. Their manipulation is thus critical to implementing heat management based on the structural design. To explore the possibility of controlling the damping of sound waves, we used high spectral contrast Inelastic X-ray Scattering (IXS) to comparatively study terahertz acoustic damping in a dilute suspension of 50 nm nanospheres in glycerol and on pure glycerol. Bayesian inference-based modeling of measured spectra indicates that, at sufficiently large distances, the spectral contribution of collective modes in the glycerol suspension becomes barely detectable due to the enhanced damping, the weakening, and the slight softening of the dominant acoustic mode.

Терапевтический эффект наноалмазов взрывного синтеза при кобальтиндуцированном дерматите

The aim of the research. To evaluate the therapeutic eff ect of modifi ed nanodiamonds (MND) of explosive synthesis for treatment of allergic contact dermatitis induced by cobalt ions. Material and methods. Th e study was performed on guinea pigs. Th e animals were divided into 3 groups (6 animals in each group). Allergic contact dermatitis was initiated using 2% aqueous solution of cobalt nitrate applied to the animals’ skin for 14 days according to the common procedure. For allergic contact dermatitis treatment, glycerol and MND suspension with the nanoparticle concentration of 5g · l-1 prepared in glycerol were used. MND with high colloidal stability in water suspensions and the average nanoparticle cluster size of d50 = 50nm was used in the work. Th e animals of group I were controls: aft er allergic contact dermatitis development, their skin was not treated by any means for 7 days. Th e animals in groups II and III were experimental: aft er allergic contact dermatitis initiation, their skin was treated for 7 days using glycerol and MND suspension, respectively. Upon experiment completion, biopsy of skin sample was performed on all animals for histological and spectral examination. The content of cobalt in skin samples was determined through atomic adsorption spectroscopy. Results. The results of histological and morphometric analysis indicate that, in the case with dermatitis modelled in guinea pigs using cobalt ions, treatment of the animals’ skin with MND suspension reduces allergic inflammation intensity. Th e therapeutic effect of MND is caused by adsorption of cobalt ions onto nanoparticles and their subsequent elimination from the skin, which complies with the atomic adsorption spectroscopy data. Conclusion. Th e prospects of MND as a new therapeutic agent for binding and elimination of chemical allergens (particularly, cobalt ions inducing the allergic contact dermatitis development) are discussed.

The antimicrobial spectrum of Xeroform®

Introduction/backgroundXeroform® is a petrolatum-based fine mesh gauze containing 3% bismuth tribromophenate. Bismuth, similar to other metals, has antimicrobial properties. Xeroform® has been used for decades in burn and plastic surgery as a donor site dressing and as a covering for wounds or partial thickness burns. Despite this, the antimicrobial spectrum of Xeroform® remains largely unknown. We examined the in-vitro efficacy of Xeroform® against common burn pathogens using zone-of-inhibition methodology in a commercial research facility. Methods/designPure strains of 15 common burn pathogens including Methicillin-resistant Staphylococcus aureus (MRSA), Methicillin-sensitive Staphylococcus aureus (MSSA), Staphylococcus epidermidis, Pseudomonas aeruginosa, Enterobacter cloacae, Escherichia coli, Candida albicans, Vancomycin resistant Enterococcus, Acinetobacter baumennii, Klebsiella pneumonia, Extended spectrum beta-lactamase producing Klebsiella, Beta hemolytic Streptococcus pyogenes, Proteus mirabilis, Serratia marcescens, and Salmonella enterica ssp. Enterica were inoculated at a strength of 106–1010 CFU/ml onto appropriate agar plates. A sterile 1 in2 Xeroform® square was placed in the center of each plate, and the Zone of Inhibition (ZOI) was measured following 18–24h of incubation at 37°C.A second bismuth pharmaceutical (bismuth subsalicylate, Pepto-Bismol®) was then tested using the same methodology against the same strains of MRSA, MSSA, E. coli, K. pneumonia and S. marcescens. Finally, 3% w/v bismuth tribromophenate in glycerol suspension was tested against 13 burn pathogens for antimicrobial activity independent of the Xeroform® dressing by measure of Zone of Inhibition. Results/findingsFor Xeroform®, none of the fifteen pathogens had a measurable zone of inhibition on any plate. Bismuth subsalicylate showed a zone of inhibition for MSSA in 3 plates (mean of 47.2mm), in one of three plates for MRSA (13.8mm), and in one of three plates for S. marcesens (89.6mm). There was no zone of inhibition seen for K. pneumonia or E. coli. Bismuth tribromophenate, when not bound to Xeroform® showed activity against 12 of 13 pathogens. Conclusions/implicationsWhile bismuth subsalicylate, and bismuth tribromophenate unbound to Xeroform® demonstrate antimicrobial activity, it appears that Xeroform® dressings do not. The utility of Xeroform® in burn medicine may relate more to use as an impervious dressing than to antimicrobial effect. Donor sites are clean surgical wounds and clean partial thickness burns may have minimal colonization present. In such circumstances, an inactive and impervious dressing may be all that is necessary to promote wound healing.

Multifunctional Cu/Ag quantum dots on TiO2 nanotubes as highly efficient photocatalysts for enhanced solar hydrogen evolution

Metallic Cu/Ag quantum dots on TiO2 nanotubes (Cu/Ag@TNT) have been prepared by a photodeposition method. The structural, optical, and morphological properties of the nanostructured composites have been characterized by a series of techniques, including X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance ultraviolet–visible light (DRS UV–vis) spectroscopy, high-resolution transmission electron microscopy (HR-TEM), HR-TEM elemental mapping, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The hydrogen (H2) generation performance of Cu/Ag@TNT catalyst was carried out in aqueous glycerol suspension under natural solar light. Optimized Cu/Ag@TNT (CAT-2.0) showed enhanced photocatalytic H2 evolution rate compared with monometallic Cu@TNT (CT-2.0), Ag@TNT (AT-2.0), and TNT. Furthermore, the role of Cu and Ag quantum dots present in Cu/Ag@TNT photocatalysts was elucidated by illuminating the reaction system under visible and UV–visible light. The superior photocatalytic H2 evolution rate of CAT-2.0 was claimed due to the localized surface plasmon resonance (LSPR) effect of Ag-injected visible-light-generated charge carriers into the conduction band (CB) of the TiO2 catalyst, while the Cu co-catalyst acts as an electron acceptor from TiO2 for reduction of H+ ions in solution into H2 gas. In this way, the synthesized photocatalyst was activated by the UV and visible region of solar light and the charge carriers’ lifetime was prolonged, and thus the electron–hole pairs were effectively utilized for H2 generation. A plausible reaction mechanism of the Cu/Ag@TNT photocatalyst was suggested by explaining the beneficial effects, namely the LSPR effect of Ag and the co-catalytic role of Cu for enhanced H2 evolution.

Wheat gluten based percolating emulsion gels as simple strategy for structuring liquid oil

Structuring liquid oils into solid fats without partially hydrogenated oils (PHOs) can decrease trans fats intakes, now become emergent technical challenge and demanding task. This paper presented a simple and economic strategy for structuring liquid oils by using wheat gluten (WG) stabilized oil-in-glycerol emulsion gels. The WG was firstly dissolved in edible glycerol at 130 °C, and emulsion gels were then prepared through homogenization of high corn oil volume fraction (φoil = 60%) with the glycerol suspension of WG at room temperature. Both WG and edible glycerol are widely available low-cost food ingredients. Confocal laser scanning microscopy (CLSM) images clearly indicated the formation of WG protein percolating oil-in-glycerol emulsion gels. Gel trapping technology (GTT) and interfacial tension decay were applied to characterize the adsorbed monolayer and the absorption behavior of wheat proteins (WG, gliadin-rich fraction, and glutenin-rich fraction) at the oil-glycerol interface. The results revealed that gliadin played a dominant role in the formation of interfacial architecture, but the synergistic interfacial effects of glutenin and gliadin were also observed. The WG based emulsion gels exhibited higher elastic, shear thinning behavior, good thixotropic recovery, and heat stability, which showed the potential application in alternatives for plastic fat, such as spreads, and other delivery systems for functional ingredients without PHOs.

The incorporation of polar monomers in copolymers based on styrene and divinylbenzene obtained from glycerol suspension polymerization

Porous copolymer networks based on styrene (STY) and divinylbenzene (DVB) containing polar monomer (methacrylamide — MAM, methacrylic acid — MAA or acrylonitrile — ACN) were prepared by suspension polymerization using glycerol as a dispersant medium. Poly(styrene-co-methacrylamide-co-divinylbenzene), poly(styrene-co-methacrylic acid-co-divinylbenzene) and poly(styrene-co-acrylonitrile-co-divinylbenzene) were synthesized using mixtures of toluene with 2-butanone, toluene and 2-butanone and n-heptane with ethylacetate, respectively at different dilutions: 50%, 100% and 120% (v/v). The copolymers were characterized by bulk density, infrared spectrometry (FTIR) and elemental analysis (CHN). Morphological features of the copolymer pearls were evaluated by microscopic analysis and correlations between porous structure and parameters of reaction were found. The copolymers presented high incorporation of polar monomers. The pearl porosities and visual appearances had a strict relation with the monomer type and the dilution degree employed in synthesizing them.

Residues Distant from the Active Site Influence Protein-tyrosine Phosphatase 1B Inhibitor Binding

Regions of protein-tyrosine phosphatase (PTP) 1B that are distant from the active site yet affect inhibitor binding were identified by a novel library screen. This screen was based on the observation that expression of v-Src in yeast leads to lethality, which can be rescued by the coexpression of PTP1B. However, this rescue is lost when yeast are grown in the presence of PTP1B inhibitors. To identify regions of PTP1B (amino acids 1-400, catalytic domain plus 80-amino acid C-terminal tail) that can affect the binding of the difluoromethyl phosphonate (DFMP) inhibitor 7-bromo-6-difluoromethylphosphonate 3-naphthalenenitrile, a library coexpressing PTP1B mutants and v-Src was generated, and the ability of yeast to grow in the presence of the inhibitor was evaluated. PTP1B inhibitor-resistant mutations were found to concentrate on helix alpha7 and its surrounding region, but not in the active site. No resistant amino acid substitutions were found to occur in the C-terminal tail, suggesting that this region has little effect on active-site inhibitor binding. An in-depth characterization of a resistant substitution localizing to region alpha7 (S295F) revealed that this change minimally affected enzyme catalytic activity, but significantly reduced the potency of a panel of structurally diverse DFMP PTP1B inhibitors. This loss of inhibitor potency was found to be due to the difluoro moiety of these inhibitors because only the difluoro inhibitors were shifted. For example, the inhibitor potency of a monofluorinated or non-fluorinated analog of one of these DFMP inhibitors was only minimally affected. Using this type of library screen, which can scan the nearly full-length PTP1B sequence (catalytic domain and C-terminal tail) for effects on inhibitor binding, we have been able to identify novel regions of PTP1B that specifically affect the binding of DFMP inhibitors.

Emulsions Which Appear Brightly Colored upon Illumination with White Light

Particular emulsion compositions of divinylbenzene, octane, and methyl methacrylate, dispersed with sodium dodecyl sulfate surfactant into a glycerol suspension medium, exhibit bright colors upon illumination with white light. The colors shift across the visible spectrum as a function of temperature and emulsion composition. As described in this paper, the “colored” emulsions are the consequence of an exact matching of the refractive index of the droplet phase with that of the continuous phase over a narrow range of wavelengths of light. Other wavelengths of light scatter. Light extinction spectra measure the wavelength at which the refractive index of droplet and continuum match and allow calculation of the refractive index of the droplet phase. The Rayleigh−Gans−Debye model of light scattering semiquantitatively describes the trends in color as a function of temperature and emulsion composition.

Polymerization of brightly colored emulsions in a glycerol suspension medium

Upon emulsification of a mixture of methyl methacrylate or methacrylic acid monomer, along with divinylbenzene crosslinker and octane porogen into a glycerol suspension medium, brightly colored emulsions form. The bright colors of the emulsion originate from an exact matching of the refractive index of the emulsion droplets with that of the glycerol medium only at certain wavelengths of light – other wavelengths of light scatter. Polymerization of the brightly colored emulsions yields three different latex morphologies depending upon the polymerization temperature and the type of emulsifier, monomer, initiator, or hydrocarbon applied. The latex morphologies obtained range from large porous latex (1–10 µm in size) to medium-sized porous latex (0.1–1 µm in size) to small latex (up to 0.1 µm in size).

The M Intermediate of Pharaonis Phoborhodopsin Is Photoactive

The retinal protein phoborhodopsin (pR) (also called sensory rhodopsin II) is a specialized photoreceptor pigment used for negative phototaxis in halobacteria. Upon absorption of light, the pigment is transformed into a short-wavelength intermediate, M, that most likely is the signaling state (or its precursor) that triggers the motility response of the cell. The M intermediate thermally decays into the initial pigment, completing the cycle of transformations. In this study we attempted to determine whether M can be converted into the initial state by light. The M intermediate was trapped by the illumination of a water glycerol suspension of phoborhodopsin from Natronobacterium pharaonis called pharaonis phoborhodopsin ( ppR) with yellow light (>450 nm) at −50°C. The M intermediate absorbing at 390 nm is stable in the dark at this temperature. We found, however, that M is converted into the initial (or spectrally similar) state with an absorption maximum at 501 nm upon illumination with 380-nm light at −60°C. The reversible transformations ppR ⇔ M are accompanied by the perturbation of tryptophan(s) and probably tyrosine(s) residues, as reflected by changes in the UV absorption band. Illumination at lower temperature (−160°C) reveals two intermediates in the photoconversion of M, which we termed M′ (or M′ 404) and ppR′ (or ppR′ 496). A third photoproduct, ppR′ 504, is formed at −110°C during thermal transformations of M′ 404 and ppR′ 496. The absorption spectrum of M′ 404 (maximum at 404 nm) consists of distinct vibronic bands at 362, 382, 404, and 420 nm that are different from the vibronic bands of M at 348, 368, 390, and 415 nm. ppR′ 496 has an absorption band that is shifted to shorter wavelengths by 5 nm compared to the initial ppR, whereas ppR′ 504 is redshifted by at least 3 nm. As in bacteriorhodopsin, photoexcitation of the M intermediate of ppR and, presumably, photoisomerization of the chromophore during the M → M′ transition result in a dramatic increase in the proton affinity of the Schiff base, followed by its reprotonation during the M′ → ppR′ transition. Because the latter reaction occurs at very low temperature, the proton is most likely taken from the counterion (Asp 75) rather than from the bulk. The phototransformation of M reveals a certain heterogeneity of the pigment, which probably reflects different populations of M or its photoproduct M′. Photoconversion of the M intermediate provides a possible pathway for photoreception in halobacteria and a useful tool for studying the mechanisms of signal transduction by phoborhodopsin (sensory rhodopsin II).

Surface roughness of cellulose hollow fiber dialysis membranes and platelet adhesion.

A great deal of research has been conducted focusing on membrane materials with reference to their blood compatibility, but blood compatibility is influenced both by the material used in membranes and their structure, and by the flow conditions at the membrane surface. Accordingly, the relationship between membrane surface roughness and hemocompatibility has been evaluated using five types of membranes of differing surface roughness by evaluating the inner surfaces of the hollow fibers by atomic force microscopy (AFM) and by measuring platelet adhesion ratios using bovine blood. The yield stress, which equates to flow characteristics, was also evaluated using a glycerol suspension of polymethylmethacrylate (PMMA), a Bingham fluid. It was found that membranes having rough surfaces had high platelet adhesion ratios and poor hemocompatibility, whereas those with smoother surfaces had lower platelet adhesion ratios and better hemocompatibility. Measurement of the yield stresses for these membranes revealed higher values for those with rough surfaces, and lower values for those with smoother polyethylene glycol (PEG) grafted surfaces. This suggests that flow conditions at the membrane surface differ according to its surface roughness, and that this difference in flow conditions also influences hemocompatibility.

Examination of whole milk powder by confocal laser scanning microscopy

Confocal laser scanning microscopy was used to examine components of whole milk powder. Powder was dispersed in a glycerol suspension containing a fat-soluble fluorescent dye which was excited by laser light to produce images of the fat at the surface of and inside the whole milk powder particle. Lactose crystals, produced in the milk prior to spray drying, were seen to be in the diamond-like, α-hydrate form. The surface coverage and the stability of a wetting agent sprayed on to the surface of whole milk powder particles were examined. The wetting agent was shown to be located as a thin surface layer that partly migrated into creases and folds on the particle surface during storage at 37°C.

The Accuracy of a Paediatric Dosing Device

A device commonly supplied by pharmacies for measuring paediatric oral liquid medicines was examined for accuracy in the hands of different operators and with liquid medicines of different characteristics. The device provided acceptable accuracy with water, but not with glycerol or paracetamol suspension. It may not be suitable for use with viscous liquids.

Biotin assay using lyophilized and glycerol-suspended cultures

An improved instant and convenient biotin bioassay method using lyophilized cells of Lactobacillus plantarum and glycerol-suspended cells of Saccharomyces cerevisiae were established. In addition, a new biotin bioassay method with a bioB − mutant strain (C 162) of Escherichia coli was established. Polyvinyl pyrrolidone solution was effective as the suspending medium for lyophilization or glycerol suspension of the cells. Satisfactory standard curves were obtained by the paper disk method and turbidimetric method with lyophilized cells of L. plantarum and E. coli C 162 and glycerol-suspended cells of S. cerevisiae. These lyophilized or glycerol-suspended cells, which were preserved at −20°C, could be used for the assay for more than one year.

The disinfectant action of glycerol in varying concentrations

Previous studies of the disinfectant action of glycerol have for the most part been conducted in relation to its supposed destructive action on invading organisms in vaccine virus. M. J. Rosenau made an exhaustive investigation of the subject in 1903 and concluded that “Glycerol has distinct but very feeble germicidal and antiseptic properties.” F. R. Blaxall reported a similar study in 1902-3. his work including only one concentration of glycerol, 50 per cent. More recently G. Mathers and G. H. Weaver have noted the remarkable viability (14 to 30 days) of various micrococci and streptococci in 50 per cent. glycerol suspension, and the persistence of the organisms for 90 days on blood agar lightly covered with 50 per cent. glycerol. Our own work was undertaken in connection with the study of the specific effects of salt solutions upon the permeability of bacterial cells, and in connection with this investigation the effect of glycerol in concentrations varying from 9.2 per cent. to 100 per cent. has been determined, Bacillus coli being the test organism. The glycerol used was an analyzed commercial preparation (Merck) with maximum limits of foreign substances .1814 per cent. The analysis showed absence of carbonizable matters, and heavy metals. Pure, ammonia free water was used in making solutions, and for the controls. Glycerol solutions of varying concelitrations (9.2, 27.6, 46.0, 64.4, 82.8, 100 per cent.) were made up in 50 and 100 c.c. portions. Young cultures of B. coli (16-20 hours) were washed from agar slants with 2-3 c.c. of the test solution. One c.c. of this suspension was added to the bottles of the solution, and after dilution, agar plates were made. The solutions were incubated at 37°, one c.c. portions being removed at definite time intervals and plated after dilution.