Effect of water content on thermal and dynamic mechanical properties of xanthan powder: A comparison between standard and novel techniques

In this work, the sorption isotherms of xanthan powder obtained under static and dynamic conditions and their fitting with mathematical models were discussed. The transitions within xanthan-water systems have been investigated using a standard material characterization technique - Differential Scanning Calorimetry (DSC) - and two novel techniques - Dynamic Mechanical Thermal Analysis (DMTA) material pocket and Phase Transition Analysis (PTA). It was found that within water-xanthan systems, the onset temperature for the melting of freezable water obtained from DSC method was in agreement with freezable water melting peaks obtained via DMTA material pocket at levels of hydration when the freezable water was present. Also, low-temperature transitions, related to polysaccharide-water interactions, were observed by both techniques within xanthan systems which contained no freezable water. However, the use of the PTA technique was limited to xanthan systems with low water content.     

The compatibility of the polystyrene/acrylonitrile-butadiene-styrene grafted copolymer system

Summary The study of polystyrene (PS)/acrylonitrile-butadiene-styrene (ABS) grafted copolymer/cyclohexanone or methylene chloride system compatibility both in concentrated solutions and solid state has been carried out by phase separation, viscosimetrical measurements and thermal behaviour.Having in view the obtained data it has been ascertained that the systems present different degrees of compatibility depending on the mixtures composition. At higher temperatures, the compatibility of the components is changed.     

Study of the compatibility in the poly (vinyl-chloride) -poly (vinyl-alcohol) system

Summary Although poly (vinyl-chloride) — PVC — and poly (vinyl-alcohol) — PVA —mixtures are used in practice for coatings, containers, fibers, few studies are encounterd concerning their compatibility (7, 8).This paper establishes both the optimum compatibility ratio and the thermal behaviour of the mixtures.The compatibility study in solid state was realised using the methodes: optical microscopy, thermogravimetry, DSC, inverse gaschromatography and IR spectroscopy.     

Effect of hydrolyzed collagen on thermal,mechanical and biological properties of poly(lactic acid) bionanocomposites

Iranian Polymer Journal - Bionanocomposites based on poly(lactic acid) (PLA), plasticized with commercial tributyl o-acetyl citrate (ATBC) and containing hydrolyzed collagen (HC) up to...     

Increasing the folate content in Egyptian baladi bread using germinated wheat flour

The main objective of this study was to increase the folate content in Egyptian baladi bread using germinated wheat flour (GWF). The effect of germination temperature and drying conditions on the folate content of wheat grains was studied. Wheat flour was substituted with unsieved and sieved GWF at different levels and the effects on folate content and the rheological properties of dough were determined. Germination of wheat grains resulted in a 3- to 4-fold higher folate content depending on the germination temperature. Maximum folate content (61 μg/100 g dry matter (DM)) occurred at 30 °C. Drying did not affect folate content in germinated grains. After replacement with GWF, folate content in both flour and bread increased 1.5- to 4-fold depending on the level of replacement. Rheological properties of dough were adversely affected by increasing replacement level (as determined by farinograph). While the folate content in bread was as high as 66 μg/100 g DM at complete replacement of flour with sieved GWF, the bread was dark and layers were not separated. After replacement of half of the flour with sieved GWF (50 g/100 g), the baladi bread was acceptable with respect to colour and layer separation. The folate content in this bread was 50 μg/100 g DM, compared with 30 μg/100 g DM in bread without GWF (0 g/100 g).     

Solidification of hesperidin nanosuspension by spray drying optimized by design of experiment (DoE)

Objective: To accelerate the determination of optimal spray drying parameters, a “Design of Experiment” (DoE) software was applied to produce well redispersible hesperidin nanocrystals.

Significance: For final solid dosage forms, aqueous liquid nanosuspensions need to be solidified, whereas spray drying is a large-scale cost-effective industrial process.

Methods: A nanosuspension with 18% (w/w) of hesperidin stabilized by 1% (w/w) of poloxamer 188 was produced by wet bead milling. The sizes of original and redispersed spray-dried nanosuspensions were determined by laser diffractometry (LD) and photon correlation spectroscopy (PCS) and used as effect parameters. In addition, light microscopy was performed to judge the redispersion quality.

Results: After a two-step design of MODDE 9, screening model and response surface model (RSM), the inlet temperature of spray dryer and the concentration of protectant (polyvinylpyrrolidone, PVP K25) were identified as the most important factors affecting the redispersion of nanocrystals. As predicted in the RSM modeling, when 5% (w/w) of PVP K25 was added in an 18% (w/w) of hesperidin nanosuspension, subsequently spray-dried at an inlet temperature of 100?°C, well redispersed solid nanocrystals with an average particle size of 276?nm were obtained. By the use of PVP K25, the saturation solubility of the redispersed nanocrystals in water was improved to 86.81?µg/ml, about 2.5-fold of the original nanosuspension. In addition, the dissolution velocity was accelerated.

Conclusions: This was attributed to the additional effects of steric stabilization on the nanocrystals and solubilization by the PVP polymer from spray drying.     

Engineered Ferritin for Magnetogenetic Manipulation of Proteins and Organelles Inside Living Cells

Magnetogenetics is emerging as a novel approach for remote‐controlled manipulation of cellular functions in tissues and organisms with high spatial and temporal resolution. A critical, still challenging issue for these techniques is to conjugate target proteins with magnetic probes that can satisfy multiple colloidal and biofunctional constraints. Here, semisynthetic magnetic nanoparticles are tailored based on human ferritin coupled to monomeric enhanced green fluorescent protein (mEGFP) for magnetic manipulation of proteins inside living cells. This study demonstrates efficient delivery, intracellular stealth properties, and rapid subcellular targeting of those magnetic nanoparticles via GFP–nanobody interactions. By means of magnetic field gradients, rapid spatial reorganization in the cytosol of proteins captured to the nanoparticle surface is achieved. Moreover, exploiting efficient nanoparticle targeting to intracellular membranes, remote‐controlled arrest of mitochondrial dynamics using magnetic fields is demonstrated. The studies establish subcellular control of proteins and organelles with unprecedented spatial and temporal resolution, thus opening new prospects for magnetogenetic applications in fundamental cell biology and nanomedicine.     

Photopinking of white PVC products: A kind of magic

Short‐term photoeffects like photograying, photobluing, and photopinking are well‐known in the polyvinyl chloride (PVC) industry. While photobluing and photograying are well understood regarding their mechanisms of occurrences there are still some missing facts. Furthermore, there are three different types of pinking effects with three different mechanisms and consequently three different ways to avoid this discoloration of mainly white PVC products. The recent paper is focusing on one hand of the photopinking of PVC products, which are stabilized with nitrogen‐containing, organic stabilizer whose mechanism was not explained until today. In the past there was neither a method to analyze nor to simulate this type of photopinking. However, the discovery of a charge transfer complex between the nitrogen‐containing substance and nitric acid gave the basic idea to investigate this phenomenon by photo‐electromotive force investigations of titanium dioxide and the nitrogen‐containing substance and by cyclo voltammetry. On the other hand, the authors are attempting to supplement the findings regarding the mechanism of the photopinking of white window profiles which are lead stabilized and which were installed north‐facing in cooler areas with high humidity. Again, a simulation and the analysis of the color‐giving substance of the north‐faced photopinking were impossible in the past. The authors assumed that antioxidants might play an important rule for this type of discoloration. They supported their hypothesis by synthesis of quinoid structures based on antioxidants, spectroscopic investigations, artificial weathering, and electrochemical calculations. J. VINYL ADDIT. TECHNOL., 24:195–207, 2018. © 2016 Society of Plastics Engineers     

Native Chemical Ligation Directed by Photocleavable Peptide Nucleic Acid (PNA) Templates

A novel peptide–peptide ligation strategy is introduced that has the potential to provide peptide libraries of linearly or branched coupled fragments and will be suited to introduce simultaneous protein modifications at different ligation sites. Ligation is assisted by templating peptide nucleic acid (PNA) strands, and therefore, ligation specificity is solely encoded by the PNA sequence. PNA templating, in general, allows for various kinds of covalent ligation reactions. As a proof of principle, a native chemical ligation strategy was elaborated. This PNA‐templated ligation includes easy on‐resin procedures to couple linkers and PNA to the respective peptides, and a traceless photocleavage of the linker/PNA oligomer after the ligation step. A 4,5‐dimethoxy‐2‐nitrobenzaldehyde‐based linker that allowed the photocleavable linkage of two bio‐oligomers was developed.