Characterization of doxycycline-loaded calcium phosphate cement: implications for treatment of aneurysmal bone cysts

Percutaneous doxycycline for treatment for aneurysmal bone cysts (ABCs) has been shown to decrease recurrence rates, however, this requires multiple procedures, includes the risks soft tissue necrosis, and does not provide structural support. We propose utilizing curettage with doxycycline-loaded calcium phosphate cement. This study aimed to evaluate the elution profile of doxycycline from calcium phosphate cement. Calcium phosphate cement underwent an in vitro elution protocol evaluating doxycycline concentrations of 0, 5, 10, and 15?mg/mL. Eluted concentrations were quantified utilizing high performance liquid chromatography at predetermined time points over 96?h. Compressive strength was evaluated both pre- and post-elution and micro-computed tomography was utilized to assess changes in cement porosity. Cement with 15?mg/mL of doxycycline maintained a higher average concentration (mean, 95% confidence intervals) (14.5?µg/mL [9.2–19.9?µg/mL]) compared to both 5?mg/mL (5.8?µg/mL [3.1–8.6?µg/mL]; P?<?0.001) and 10?mg/mL (8.4?±?µg/mL [6.0–10.9?µg/mL]; P?<?0.001). Ultimate stress significantly decreased between pre- and post-elution samples for 10?mg/mL (P=?0.001) and 15?mg/mL (P?=?0.004) groups. This study demonstrated a dose-dependent response in ultimate strength and compressive modulus with addition of doxycycline to calcium phosphate cement.     

Microscopic Determination of Carrier Density and Mobility in Working Organic Electrochemical Transistors

A comprehensive understanding of electrochemical and physical phenomena originating the response of electrolyte‐gated transistors is crucial for improved handling and design of these devices. However, the lack of suitable tools for direct investigation of microscale effects has hindered the possibility to bridge the gap between experiments and theoretical models. In this contribution, a scanning probe setup is used to explore the operation mechanisms of organic electrochemical transistors by probing the local electrochemical potential of the organic film composing the device channel. Moreover, an interpretative model is developed in order to highlight the meaning of electrochemical doping and to show how the experimental data can give direct access to fundamental device parameters, such as local charge carrier concentration and mobility. This approach is versatile and provides insight into the organic semiconductor/electrolyte interface and useful information for materials characterization, device scaling, and sensing optimization.     

Diffusivity of propolis compounds in Polylactic acid polymer for the development of anti-microbial packaging films

A major research gap is the lack of packaging materials that can provide the release of active compounds at rates suitable for a wide range of food packaging applications. For this reason an anti-microbial/antioxidant release system for food packaging applications was realized by incorporation of propolis into Polylactic acid (PLA) film. The composition of the films was modified by adding polyethylene glycol (PEG) and calcium bentonite (CB) to the initial PLA casting solution; dispersed structures in fact open the molecular network and increase migration rates. The presence of the anti-microbial compound is required essentially at the food surface where the microorganisms are numerous and where they are intended to grow. The diffusivity of four polyphenols was measured in water and ethanol as food simulating liquids (FSL) and the concentration of additives at the interface PLA/Food Simulant was calculated using Fickian models. The external mass transfer coefficient at the interface polymer/FSL could be neglected (with Bi number higher than 200). This is due to the low diffusivity values of propolis polyphenols in the PLA matrix (0.03–0.83 × 10–13 m²/s) which lead to a predominant internal mass transfer phenomenon compared to the external one in the system PLA/water. The concentration at interface at equilibrium was different for each substance and depended of the thermodynamical parameter K. Such a delivery system for direct contact with liquid aqueous medium would be a very efficient delivery system because some active agents (polyphenols acids) would be released in relevant quantity in the food whereas others (flavonoids) would remain in the polymer to act at the polymer/food interface.     

Droplet Buildup and Water Retention Prediction in Condensation Processes

A numerical model for the prediction of the buildup of a moist air condensate layer is presented. The model simulates the process of birth, growth, coalescence, and possible motion of each individual condensate droplet. Due to its computational intensity, such an approach is not feasible for the simulation of complex configurations of industrial interest, but allows for the identification of the major parameters influencing the water layer build up process. In particular, the model requires, as input data, the values of droplet advancing and receding contact angles, and computes the unsteady evolution of the droplet distribution. The droplet movement, as well as the moving droplet velocity, is detected by a force balance. Proper average values of practical interest, such as wetted area and water retention, are evaluated and compared with published experimental data. Such average data can be used as calibration values for global integral parameters usually required in order to incorporate the water layer effect within CFD computations in more complex geometries. The results show a good agreement with the experimental data and confirm that our model, although based on a small number of independent parameters (essentially the contact angles) and a relatively simple schematization of the complex physics behind the droplet history, predicts the water retention well within engineering accuracy. In particular, the hysteresis between advancing and receding angles seems the dominant effect.     

Transformation of multi-walled carbon nanotubes to amorphous nano-spheres,micron-size rods and flakes by oxidative sulfation reaction

This study unveils a chemical functionalization provoked phase transformation in the naphthalene modified multi-walled carbon nanotubes (MWCNTs) and the associated formation of amorphous carbonaceous particles of various size and morphology. Functionalized nanotubes were prepared by a sulfonation-oxidization and a highly corrosive oxidative sulfation reaction then characterized by means of thermogravimetry/mass spectrometry, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy and Raman spectroscopy. In spite of the small change in the composition of sulfonation and sulfation reaction mixtures, conventional sulfonation with oleum resulted in lower sulfonation and higher oxidative conversion of MWCNTs accompanied with a mediated exohedral amorphization of the nanotubes, induced by the yield of sp³ hybridization defect introduction. On the other hand, the newly applied oxidative sulfation reaction provided severe oxidative etching, cutting and shortening of MWCNTs with a subsequent high conversion of sulfate derivatisation of oxidized functionalities, which induced complete collapse and phase transformation of the nanotubes. Amorphization and phase transformation of oxidative sulfated MWCNTs have led to the formation of highly dispersed nano- and micron-size amorphous carbon spheres, rods and flake-like structures. Water based colloidal systems of excellent stability were prepared from the oxidative sulfated carbonaceous material. Consequently, the employed highly corrosive sulfation reaction is capable to provide highly functionalized carbonaceous nano and micro-size particles from MWCNTs.     

Fine milling in applied mechanochemistry

This review paper is devoted to application of mechanochemistry in extractive metallurgy, crystal engineering, materials engineering, coal industry, building industry, agriculture, pharmacy and waste treatment. In extractive metallurgy the most commercially attractive potential applications using fine milling (Activox, Melt) will be illustrated. Mechanochemical approach in crystal and materials engineering will focus on the non-equilibrium processing of materials and their current and potential applications. In agriculture the technological advantages of mechanochemical methods over traditional methods for improving the solubility of natural phosphates will be documented. In pharmacy, the selected examples of fine milling application will show the improved bioavailability of drugs. The examples of fine milling utilization in coal industry, building industry and waste treatment are also given. Simplification of the processes, ecological safety and the product extraordinariness characterize the application of fine milling in mechanochemistry.     

Aromatic hydroxylation is a major metabolic pathway of the mycotoxin zearalenone in vitro

Zearalenone (ZEN) is a common mycotoxin, for which only reductive metabolites have been identified so far. We now report that ZEN is extensively monohydroxylated by microsomes from human liver in vitro. Two of the major oxidative metabolites arise through aromatic hydroxylation and are catechols. Their chemical structures have been unambiguously determined by using deuterium‐labeled ZEN and by comparison with authentic reference compounds. Moreover, both catechol metabolites of ZEN were substrates of the enzyme catechol‐O‐methyl transferase. One of the monomethyl ethers represented the major metabolite when ZEN was incubated with rat liver slices, thus demonstrating that catechol formation also takes place under in vivo‐like conditions. Out of ten major human cytochrome P450 (hCYP) isoforms only hCYP1A2 was able to hydroxylate ZEN to its catechols with high activity. Catechol formation represents a novel pathway in the metabolism of ZEN and may be of toxicological relevance.     

Determination of antioxidant compounds and antioxidant activity in commercial oilseeds for food use

Different commercial edible oilseed samples were analyzed in order to evaluate the compounds involved in antioxidant activity. Fatty acids, triacylglycerols, tocopherols, chlorophylls, β-carotene, squalene, phenolic compounds and CIE L^∗a^∗b^∗ coordinates were assayed. Strong chemical variability depending on the oilseed variety was observed. Antioxidant activity was evaluated for the oils, both for their methanol-soluble phase and the fraction insoluble in methanol. DPPH radical scavenging activity expressed in TEAC ranged between 0.45 and 2.30 mmol/l in peanut and maize oils, respectively. Free radical scavenging activity was mainly influenced by tocopherols content (r = +0.70) in oils and polyunsaturated fatty acids (r = +0.61) in the fraction nonsoluble in methanol. Variability of the correlation between the antioxidant activity and the composition of the oilseeds could be attributed to the differences in the squalene, chlorophylls, carotenoids, and phenols contents of the oils and their mutual interactions.     

Effects of milling on co-precipitated 3Y-PSZ powders

The present research compares properties and behaviour of co-precipitated 3Y-PSZ powders submitted, after co-precipitation, to different milling treatments. The characteristics of the different products were evaluated by measurement of particle size distribution, thermogravimetric analysis, X-ray diffraction, specific surface area and scanning electron microscopy analysis. It has been demonstrated that 1 h of attrition milling enables the production of powders containing soft agglomerates of nanometric particles: the dispersing liquid used on milling has little influence. Crystallisation into a cryptocrystalline structure of the amorphous powder is achieved after 1 h of high energetic milling, avoiding thermal treatments.