Effects of maturation and aging on the pressure‐bearing region of the plantaris longus tendon of the bullfrog (Lithobates catesbeianus)

The plantaris longus tendon (PLT) in bullfrog develops a fibrocartilage‐like tissue in the area that is functionally subject to compressive forces. The aim of this study was to analyze the modifications of the pressure‐bearing region in bullfrog PLT with different ages (7, 180, and 1,080 days after the end of metamorphosis) using histomorphometric, ultrastructural and biochemical methods. Weak basophilia and cells with a fibroblastic phenotype were observed in the compression region at 7 days of age. On the other hand, a large area of intense tissue basophilia associated with a chondroblast‐like cell population was noted at the other ages. Collagen fibers exhibited a three‐dimensional network‐like arrangement at all ages. The number of connective tissue cells increased between 7 and 180 days of age and was reduced in older animals. The 180‐day‐old animals presented a well‐developed pericellular matrix rich in proteoglycans. The mean diameter of collagen fibrils increased from 7 to 180 days and was the same at 1,080 days. Glycosaminoglycan content was higher in 7‐day‐old animals. A higher amount of hydroxyproline was observed at 180 and 1,080 days. The swelling test showed a significant increase of wet weight in 7‐day‐old animals. In conclusion, the alterations that occur in the pressure‐bearing of bullfrog PLT are the result of physiological alterations of the animal with the maturation and aging. Microsc. Res. Tech. 77:797–805, 2014. © 2014 Wiley Periodicals, Inc.     

Effect of Aloe vera application on the content and molecular arrangement of glycosaminoglycans during calcaneal tendon healing

Although several treatments for tendon lesions have been proposed, successful tendon repair remains a great challenge for orthopedics, especially considering the high incidence of re‐rupture of injured tendons. Our aim was to evaluate the pharmacological potential of Aloe vera on the content and arrangement of glycosaminoglycans (GAGs) during tendon healing, which was based on the effectiveness of A. vera on collagen organization previously observed by our group. In rats, a partial calcaneal tendon transection was performed with subsequent topical A. vera application at the injury site. The tendons were treated with A. vera ointment for 7 days and excised on the 7^th, 14^th, or 21^st day post‐surgery. Control rats received ointment without A. vera. A higher content of GAGs and a lower amount of dermatan sulfate were detected in the A. vera‐treated group on the 14^th day compared with the control. Also at 14 days post‐surgery, a lower dichroic ratio in toluidine blue stained sections was observed in A. vera‐treated tendons compared with the control. No differences were observed in the chondroitin‐6‐sulfate and TGF‐β1 levels between the groups, and higher amount of non‐collagenous proteins was detected in the A. vera‐treated group on the 21^st day, compared with the control group. No differences were observed in the number of fibroblasts, inflammatory cells and blood vessels between the groups. The application of A. vera during tendon healing modified the arrangement of GAGs and increased the content of GAGs and non‐collagenous proteins. Microsc. Res. Tech. 77:964–973, 2014. © 2014 Wiley Periodicals, Inc.     

Synergistic Effect on Wettability of Mixtures of Amine Oxides,Alkylpolyglucosides, and Ethoxylated Fatty Alcohols

The mixture proportions of three surfactants, i.e. an alkylpolyglucoside (APG), an ethoxylated fatty alcohol, and an amine oxide (AO), were optimized by applying Response Surface Methodology in order to achieve the surfactant ratio that produces the highest wetting power. The synergistic effect of the binary samples of AO with the other surfactants was firstly verified. An improvement in this synergistic effect on wettability was found in the ternary mixture. In the experimental range analyzed, the surfactant concentration ratio that produced the highest wettability was a composition with 19.3 % APG, 30.1 % ethoxylated alcohol, and 50.6 % lauramine oxide.     

Dissipative effects and detonation in dusty media

The influence of phase interaction on the spatial structure of the detonation wave in dusty media is discussed. It is shown that dissipation of the energy of low-frequency acoustic perturbations in the gas phase may be drastically enhanced by the presence of minor fractions of small-size chemically inert solid particles and affect stability of perturbations with a scale comparable with the cell size of the gas detonation wave. A hypothesis is proposed that there exists an additional (dissipative) mechanism assisting in detonation suppression in the gas suspension owing to intense momentum transfer between the phases in an unsteady acoustic field in the reaction zone. Under certain conditions, this mechanism can substantially change the spectrum of unstable perturbations and attenuate spatial nonhomogeneity of the detonation wave at small energy expenses for acceleration and heating of particles. Owing to this fact, perturbation energy dissipation can affect the parameters and conditions of existence of the self-sustained detonation regime in the gas suspension.     

Collagen-based hydrogel films as drug-delivery devices with antimicrobial properties

Collagen (coll)-containing hydrogel films were prepared by mixing degraded collagen with monomers such as acrylamide (AAm), and 2-hydroxy ethylmethacrylate (HEMA) before the polymerization/cross-linking of composites as p(coll-co-AAm), and p(coll-co-HEMA), respectively. These materials were used as drug-delivery devices for potential wound dressing materials by loading and releasing of model drugs such as gallic acid (GA) and naproxen (NP). A linear release profile was obtained up to 32-h release from GA-loaded p(coll-co-AAm) interpenetrating polymeric networks films, and 36-h linear release profile of NP for p(coll-co-HEMA). Furthermore, metal nanoparticles such as Ag and Cu prepared within these hydrogel films offered antimicrobial characteristic against known common bacteria such as Escherichia coli, Bacillus subtilis, and Staphylococcus aureus.     

Experience in the Development and Production of Thermal-Neutron Detectors at the IBR-2 DSC (Review)

Instruments and Experimental Techniques - One of the most important activities of the IBR-2 DSC is the development of detector technologies, which will be used as a basis in designing detectors for...     

Hybrid Technology for Surface Hardening of Structural Steel

Russian Engineering Research - Hybrid surface hardening consisting of quenching with inductive heating by high-frequency current and subsequent ultrasonic surface plastic deformation is considered....     

Assessing External Defects at Manufacturing Enterprises

Russian Engineering Research - A method is outlined for calculating the components responsible for external defects in manufacturing. A classical quality-control tool is employed to analyze the...