A new acylated and oleanane-type triterpenoid saponin from Gypsophila arrostii roots

A new acylated and triterpenoidal saponin, named GS1, was isolated from the roots of Gypsophila arrostii Guss. On the basis of acid hydrolysis, comprehensive spectroscopic analyses and comparison with spectral data of known compounds, its structure was established as 3-O-β-D-xylopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-{21-O-[(E)-3,4,5trimethoxycinnamoyl]}21-hydroxygypsogenin 28-O-β-D-glucopyranosyl-(1→2)- [β-D-arabinopyranosyl-(1→3)]-β-D-xylopyranosyl-(1→3]-α-L-rhamnopyranosyl ester. This article deals with the isolation and structural elucidation of new acylated and oleanane-type saponin.     

Hemodialysis‐related headache

Headache is one of the most frequently encountered neurological symptoms during hemodialysis. According to International Classification of Headache criteria dialysis‐related headache was defined as the headache occurring during hemodialysis with no specific characteristic. It resolves spontaneously within 72 hours after the hemodialysis session ends. There are few studies in the literature investigating the clinical features of dialysis headache. The pathophysiology of hemodialysis‐related headache is not known, but various triggering factors have been identified, including changes in blood pressure, serum sodium and magnesium levels during hemodialysis sessions, caffeine deprivation and stress. The aim of this article is to evaluate and analyze features of headache in patients undergoing hemodialysis.     

On an iterative deadlock prevention approach for automated manufacturing systems

In Hu (Transactions of the Institute of Measurement and Control 33:59–76, 2011), Petri nets are utilized to describe, analyse and control automated manufacturing systems (AMS). In order to suppress deadlock occurrences in AMS, a method to derive the bad markings iteratively using a mixed integer programming-based algorithm is proposed. To validate the effectiveness and efficiency of the proposed approach, two examples were demonstrated in Hu (Transactions of the Institute of Measurement and Control 33:59–76, 2011). This paper shows that the uncontrolled Petri net model in one of the examples is incorrect. It is also shown that the structural complexity of the computed monitors for both examples can be reduced with the same or more permissive system behaviours.     

Polymers for medical and tissue engineering applications

Recent decades have seen great advancements in medical research into materials, both natural and synthetic, that facilitate the repair and regeneration of compromised tissues through the delivery and support of cells and/or biomolecules. Biocompatible polymeric materials have become the most heavily investigated materials used for such purposes. Naturally‐occurring and synthetic polymers, including their various composites and blends, have been successful in a range of medical applications, proving to be particularly suitable for tissue engineering (TE) approaches. The increasing advances in polymeric biomaterial research combined with the developments in manufacturing techniques have expanded capabilities in tissue engineering and other medical applications of these materials. This review will present an overview of the major classes of polymeric biomaterials, highlight their key properties, advantages, limitations and discuss their applications. © 2014 Society of Chemical Industry     

Fracture load and microcrack comparison of crowns manufactured from tooth‐shaped and traditional blocks

This study intended to analyze microcracks and fractographic markings on the surface of all ceramic crowns after milling and compare the fracture loads. 90 crowns were manufactured from two feldspathic (Priticrown‐Pr and Vita Mark II‐Vi) and a lithium disilicate (EmaxCAD‐Em) blocks (n = 30). Two groups (n = 15) were prepared for each ceramic. In the first group, crowns were analyzed twice via the fluorescent penetrant method for microcrack detection, after the manufacturing process and thermal cycles. The load to fracture test was applied at a crosshead speed of 0.5 mm/min until catastrophic failure. Second group crowns were directly cemented onto the Co‐Cr dies following the manufacturing process and loaded to fracture. Fractographic markings were analyzed through scanning electron microscope. Spearman correlation analysis, Kruskal–Wallis H test, Mann–Whitney U test, and Wilcoxon Signed Rank test were applied (α = .05). Fracture loads of Em crowns were higher than other groups (p < .05), with and without the aging procedure. Except for second group Pr (r = ?.532), no significant relationship was found between microcrack numbers and fracture loads (p > .05). Thermal cycling did not affect microcrack numbers and fracture loads (p > .05). Tooth‐shaped multilayered Pr blocks did not provide an advantage in terms of microcrack and fracture loads.     

Revised stratigraphy of the Tertiary deposits of Istanbul and their engineering properties

For over 50 years, the Upper Oligocene–Upper Miocene sedimentary sequence in Istanbul has been considered to be formed of two distinct sequences separated by an unconformity. However, recent field observations and an analysis of numerous borehole data indicate the Gürp?nar, Çukurçe?me and Güngören Formations are in fact a single sequence of alternating clay–sand/sandstone beds/lenses, here named the Avc?lar Formation. The Bak?rköy Formation, which is typically composed of carbonate rocks, conformably overlies the Avc?lar Formation. The paper provides the geotechnical parameters of the units within the Avc?lar Formation which it is hoped will facilitate selecting suitable geotechnical and engineering geological parameters to represent the deposits and minimize errors in the interpretation/evaluation of in-situ conditions.     

Long-term microleakage trends in access cavities conditioned with phosphoric acid and deproteinizing agent for root-canal-treated teeth: an investigation of fluid filtration and microscopy analysis

This study evaluated the long-term microleakage of access cavities conditioned with phosphoric acid and deproteinizing agents for root-canal-treated teeth using fluid filtration and microscopical analysis. Occlusal surfaces of extracted human mandibular premolars (N = 90) were removed leaving a 4 mm coronal length from the cemento-enamel junction. After root canal treatment, the specimens were randomly divided into four experimental groups (n = 21) and the remaining teeth were used for positive control group (n = 6): SB: 35% H₃PO₄ + Adper Single Bond 2; SSB: 35% H₃PO₄ + 5.25% NaOCl + 10% Sodium ascorbate (C₆H₇NaO₆) + Adper Single Bond 2; XP: 35% H₃PO₄₊XP Bond; SXP: 35% H₃PO₄₊5.25% NaOCl + 10% Sodium ascorbate + XP Bond. All cavities were restored with a resin composite (Filtek Z250). After removing the root filling from the apical side, teeth were subjected to fluid filtration test for 1 week, 6 and 12 months followed by ×2500 thermocycling after 1st week and 6th months each. Data were analyzed using one-way ANOVA and Dunnet T3 tests (α = 0.05). SEM analyses were carried out after each microleakage evaluation in two random teeth from all groups. Microleakage values in groups SB and XP presented no significant difference in any of the evaluated period (p > 0.05). Microleakage results of SXP (0.01665) group showed significant difference compared to XP (0.03377) and SB (0.03049) groups after 12 months. SSB group (0.00901) showed significantly less microleakage among all other groups (0.01665–0.03377) (p < 0.05). Prior to endodontic treatment, in access cavities, acid etching with 35% H₃PO₄ followed by the application of NaOCl and sodium ascorbate completely destroyed the collagen layer, reducing the microleakage and resin–dentin interface degradation up to 12 months.     

Capacitor Applications of Nanocomposite Films for Poly(3,4-ethylenedioxythiophene-co-pyrrole)/Multi-Walled Carbon Nanotubes and Poly(3,4-ethylenedioxythiophene-co-pyrrole)/Copper Oxide

Polypyrrole/multi-walled carbon nanotube, poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotube and their nanocomposites P(EDOT-co-Py)/multi-walled carbon nanotube and P(EDOT-co-Py)/copper (II) oxide, (CuO) in the initial feed ratio of [EDOT]₀/[Py]₀ = 1/5 were electrosynthesized on glassy carbon electrode by cyclic voltammetric method. Their characterizations were performed by cyclic voltammetric, Fourier transform infrared-attenuated total reflectance, scanning electron microscopy, energy dispersion X-ray analysis, and electrochemical impedance spectroscopy. To the best of authors’ knowledge, the first report on polypyrrole/multi-walled carbon nanotube, PEDOT/multi-walled carbon nanotube, P(EDOT-co-Py)/multi-walled carbon nanotube and P(EDOT-co-Py)/CuO nanocomposite films were comparatively examined in 0.1 M NaClO₄/CH₃CN and in 0.1 M sodium dodecyl sulfate solutions. The highest specific capacitance for PEDOT/multi-walled carbon nanotube and polypyrrole/multi-walled carbon nanotube composite films were obtained as C_sp = 306 mF × cm^?2 for 3% multi-walled carbon nanotube and C_sp = 804 mF × cm^?2 for 1% multi-walled carbon nanotube, respectively. The highest specific capacitances were obtained as C_sp = 27.40 mF × cm^?2 and C_sp = 26.90 mF × cm^?2 for P(EDOT-co-Py)/multi-walled carbon nanotube includes the wt percent of 1% multi-walled carbon nanotube and P(EDOT-co-Py)/CuO includes the wt percent of 3% CuO, respectively. The C_sp of P(EDOT-co-Py)/CNT composite films were calculated as 9.43 and 11.49 mF × cm^?2 for 3 and 5% multi-walled carbon nanotube, respectively. In addition, The EIS results were simulated with the equivalent circuit model of R_s(C_dl1(R₁(QR₂)))(C_dl2R₃).     

Synthesis,characterization and,swelling behavior of semi‐IPN nanocomposite hydrogels of alginate with poly(N‐isopropylacrylamide) crosslinked by nanoclay

pH and temperature responsive nanocomposite hydrogels were synthesized with sodium alginate (NaAlg), N‐isopropylacrylamide (NIPA), and nanoclay. The structure, morphology, thermal behavior, and swelling and deswelling behaviors of the hydrogels were studied. The NaAlgm/PNIPA/Clayn hydrogels revealed a highly porous structure in which the pore sizes decreased and the amount of pores increased with increasing the nanoclay content in the hydrogels. PNIPA retained its own characteristics regardless of the amount of NaAlg and nanoclay. The effect of pH and nanoclay content on the swelling and effect of temperature on the deswelling behavior were investigated. The equilibrium swelling ratios of the nanocomposite hydrogels increased with increasing the pH from 2 to 6. The maximum swelling was attained at pH 6. Deswelling increased with increasing the nanoclay content in the hydrogels. The hydrogels were found to be pH and temperature responsive. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43222.