Chemical structure of sulfated polysaccharides from brown seaweed (Turbinaria turbinata)

The chemical structure of three sulfated polysaccharides fractions (TtF1, TtF2, and TtF3) obtained from anion-exchange separation of aqueous extracts of brown seaweed (Turbinaria turbinate) were studied. The infrared spectra patterns showed that the fractions possess functional groups similar to that of sulfated polysaccharides. The sulfated polysaccharides fractions exhibited molecular weights of 223.5, 495.5, and 326.05 kDa, respectively, for TtF1, TtF2, and TtF3. ¹H NMR spectra of TtF2 and TtF3 contain α-anomeric protons (5–5.6 ppm), ring protons (3.4–4.4), and methyl protons (1–1.3 ppm) while that of TtF1 only exhibited ring protons and methyl protons. Rheological data were fitted to power law which revealed that the fractions were Newtonian and/or presented weak pseudoplastic behavior. Consistency values increased with concentration in all fractions. Consistency values of TtF2 were the highest, followed by TtF1 and then TtF3. Thermal degradation patterns of TtF1 and TtF2 were similar but different from that of TtF3. This study confirmed that chemical and physical characteristics of sulfated polysaccharides fractions are interrelated and provided in-depth understanding of sulfated polysaccharides of brown algae.     

The cause, prevention, and treatment of recurrent groin hernia

At present, groin hernia repair is associated with a 10% recurrence rate. Despite innumerable modifications of the Bassini technique, this depressing figure remains essentially unimproved. This article documents the two major reasons for failure and presents techniques that are simple, can be performed under local anesthesia in an outpatient setting, allow patients to return home within hours of their surgery, encourage rapid return to unrestricted activity, and are associated with a recurrence rate approaching 0%.     

Endothelial cell culture model for replication of physiological profiles of pressure, flow, stretch, and shear stress in vitro

The phenotype and function of vascular cells in vivo are influenced by complex mechanical signals generated by pulsatile hemodynamic loading. Physiologically relevant in vitro studies of vascular cells therefore require realistic environments where in vivo mechanical loading conditions can be accurately reproduced. To accomplish a realistic in vivo-like loading environment, we designed and fabricated an Endothelial Cell Culture Model (ECCM) to generate physiological pressure, stretch, and shear stress profiles associated with normal and pathological cardiac flow states. Cells within this system were cultured on a stretchable, thin (～500 μm) planar membrane within a rectangular flow channel and subject to constant fluid flow. Under pressure, the thin planar membrane assumed a concave shape, representing a segment of the blood vessel wall. Pulsatility was introduced using a programmable pneumatically controlled collapsible chamber. Human aortic endothelial cells (HAECs) were cultured within this system under normal conditions and compared to HAECs cultured under static and "flow only" (13 dyn/cm(2)) control conditions using microscopy. Cells cultured within the ECCM were larger than both controls and assumed an ellipsoidal shape. In contrast to static control control cells, ECCM-cultured cells exhibited alignment of cytoskeletal actin filaments and high and continuous expression levels of β-catenin indicating an in vivo-like phenotype. In conclusion, design, fabrication, testing, and validation of the ECCM for culture of ECs under realistic pressure, flow, strain, and shear loading seen in normal and pathological conditions was accomplished. The ECCM therefore is an enabling technology that allows for study of ECs under physiologically relevant biomechanical loading conditions in vitro.     

Preparation and Characterization of Carvacrol Loaded Polyhydroxybutyrate Nanoparticles by Nanoprecipitation and Dialysis Methods

In this investigation, preparation of carvacrol loaded polyhydroxybutyrate (PHB) nanoparticles was performed by nanoprecipitation and dialysis methods. PHB particles were obtained by nanoprecipitation method without and with low concentration of Tween 80 or pluronic as surfactant. Nano‐ and micro‐sized particles were formed with trimodal distribution and large aggregates. Size and distribution of nanoparticles were decreased when concentration of Tween 80 was increased to 1% (v/v) in water as polar phase. PHB nanoparticles had narrow size (157 nm) with monomodal distribution. Nanoparticles, which were prepared by dialysis method had 140 nm in diameter with monomodal distribution. Carvacrol was used as a lipophilic drug and entrapped in optimized nanoparticles formulation by nanoprecipitation and dialysis methods. Entrapment efficacy was 21% and 11%, respectively. Morphology of PHB nanoparticles was spherical. The results of kinetic release study showed that carvacrol was released for at least 3 days. Release kinetic parameters showed a simple Fickian diffusion behavior for both formulations. Carvacrol loaded PHB nanoparticles had good dispersion into the agar medium and antimicrobial activity against Escherichia coli. This study describes the 1st work on loading of carvacrol into the PHB nanoparticles by nanoprecipitation and dialysis methods.     

Layer-wise finite element analysis of functionally graded cylindrical shell under dynamic load

In this paper, a layer-wise finite element formulation is developed for the analysis of a functionally graded material (FGM) cylindrical shell with finite length under dynamic load. For this purpose, FGM cylinder is divided into many sub-layers and then the general layerwise laminate theory is formulated by introducing piecewise continuous approximations through the thickness for each state In this model the radial displacement is approximated linearly through each “mathematical” layer. The properties are controlled by volume fraction that is an exponential function of radius. The governing equations are derived from virtual work statement and solved by finite element method. The main contribution of the present study is to develop a discrete layerwise finite element for a 2-dimensional thick FGM cylindrical shell. Results are obtained for the time history of the displacement and stress components with different exponent “n” of functionally graded material. In addition, natural frequency and mean velocity of the radial wave propagation for different exponent “n” of functionally graded material (FGM) are studied and compared with similar ones currently obtained for FGM cylindrical shell of infinite length.