Photoelastic stress analysis of splinted and unitary implant-supported prostheses

The aim of this study was to evaluate the effects that splinting and different lengths of implants have on the stress distribution in implant-supported prostheses by photoelastic analysis. A total of five photoelastic resin models were made with different proposed situations, and 400 load applications were performed for the analysis. Compared with the unitary prosthesis, the splinted implant-supported prosthesis acted favorably in the distribution of stresses and strains to the implant (p < 0.001). The increase in length was a significant factor in the stress distribution (p < 0.05) and, ultimately, the overall reduction in stress. It was concluded that the splinted implant-supported prosthesis behaved better biomechanically compared with the unitary prosthesis.     

Real‐time mechanistic monitoring of an acetal hydrolysis using ultrafast 2D NMR

Ultrafast (UF) 2D NMR makes it possible to obtain a 2D NMR spectrum in less than a second. Here, UF‐HSQC experiments are used for the real‐time mechanistic study of an acetal hydrolysis at ¹³C natural abundance, and it is possible to characterize the presence of the hemiacetal, an intermediate with a well‐known short lifetime. The assignments are confirmed and rationalized by quantum calculations of ¹H and ¹³C NMR chemical shifts and natural bonding orbital analysis. Copyright © 2012 John Wiley & Sons, Ltd.     

Rational Design,Synthesis and Evaluation of Indole Nitrogen Hybrids as Photosystem II Inhibitors

We report the synthesis of twelve indole derivatives bearing nitro or amide groups via Fischer indole methodology followed by reduction/acetylation and amidation reactions. After thorough characterization, these indoles were subjected to a number of studies in order to evaluate their bioactive potential as photosynthesis and plant growth inhibitors. Firstly, these molecular hybrids were evaluated as photosystem II (PSII) inhibitors through chlorophyll a (Chl a) fluorescence measurement. In this study, 6-chloro-8-nitro-2,3,4,9-tetrahydro-1H-carbazole ( 15a ) and 5-chloro-2,3-dimethyl-7-nitro-1H-indole ( 15b ) showed the best results by reducing the phenomenological parameters of reaction centers ABS/RC, TR₀/RC and ET₀/RC of PSII. Electron chain blockage by these compounds may lead to diminished ATP synthesis and CO₂ fixation which interrupt the plant development. The compounds 15a and 15b both act as postemergent herbicides, reducing the dry biomass of Ipomoea grandifolia and Senna alata weeds by an average of 40% and 37%, respectively, corroborating the fluorescence results. Additionally, the molecular docking study revealed that the presence of strong electron-withdrawing groups at the indole phenyl ring is important for the ligand’s interaction with the binding pocket of protein D1 on PSII. The optimization of these molecular features is the goal of our research group in further understanding and development of new potent herbicides.     

Loading of 5-aminosalicylic in solid lipid microparticles (SLM)

5-Aminosalicylic acid (5-ASA), the active moiety of sulphasalazine, is the most commonly used drug for treating patients with inflammatory bowel disease (IBD). Its bioavailability is low, i.e. 20–30% upon oral administration and 10–35% by rectal administration. As the extent of 5-ASA absorption is very much dependent on the time-length, the drug is retained in the colon, a way to increase drug retention is the use of orally administered sustained released formulations. Solid lipid microparticles (SLM) are a viable option for site-specific targeted delivery in compressed tablets produced by direct compaction. In this study, we describe the development and characterization of 5-ASA-loaded SLM for sustained release. The solubility of 5-ASA in different types of solid lipids (e.g. cetyl palmitate, cetyl alcohol, and cetearyl alcohol) was evaluated to select the best lipid as the inert matrix-forming agent to control the release of the drug. SLM dispersions were prepared using the hot emulsification method employing the selected solid lipid, lecithin (Lipoid^®) as surfactant, dimethyl sulphoxide, and acetone stabilized with Arlacel^®. The characterization was performed by differential scanning calorimetry, thermogravimetric analysis, wide-angle x-ray diffraction, Fourier transform infrared spectroscopy measurements, optical microscopy, and scanning electron microscopy. Results show that the best lipid for dissolving the 5-ASA was cetyl palmitate and that the melting process did not affect the chemical stability of the materials. The thermal analysis suggests that 5-ASA was successfully encapsulated with the microparticles, of spherical shape and uniform size distribution.

     

Quasilinear elliptic system in exterior domains with dependence on the gradient

In this paper, we deal with a quasilinear elliptic system in exterior domains with dependence on the gradient and coupling of the equations not only inside of the domain, but also on the boundary. We prove the existence of positive, negative or sign changing weak solutions. Our approach relies on an aproximation argument and an adequate elliptic “a priori” estimate.     

Dereplication of Streptomyces sp. AMC 23 polyether ionophore antibiotics by accurate‐mass electrospray tandem mass spectrometry

Actinomycetes, especially those belonging to the genus Streptomyces, are economically important from a biotechnological standpoint: they produce antibiotics, anticancer compounds and a variety of bioactive substances that are potentially applicable in the agrochemical and pharmaceutical industries. This paper combined accurate‐mass electrospray tandem mass spectrometry in the full scan and product ion scan modes with compounds library data to identify the major compounds in the crude extract produced by Streptomyces sp. AMC 23; it also investigated how sodiated nonactin ([M + Na]⁺) fragmented. Most product ions resulted from elimination of 184 mass units due to consecutive McLafferty‐type rearrangements. The data allowed identification of four macrotetrolides homologous to nonactin (monactin, isodinactin, isotrinactin/trinactin and tetranactin) as well as three related linear dimer compounds (nonactyl nonactoate, nonactyl homononactoate and homononactyl homononactoate). The major product ions of the sodiated molecules of these compounds also originated from elimination of 184 and 198 mass units. UPLC‐MS/MS in the neutral loss scan mode helped to identify these compounds on the basis of the elimination of 184 and 198 mass units. This method aided monitoring of the relative production of these compounds for 32 days and revealed that the biosynthetic process began with increased production of linear dimers as compared with macrotetrolides. These data could facilitate dereplication and identification of these compounds in other microbial crude extracts. Copyright © 2014 John Wiley & Sons, Ltd.     

Modified carbon paste electrode for the electrochemical sensing of 3,5,6-trichloro-2-pyridinol

An electrochemical sensor for the determination of 3,5,6-trichloro-2-pyridinol (TCP), the main metabolite of the pesticide chlorpyrifos, was herein developed. TCP has greater solubility than the source pesticide, and its occurrence in ground and surface water is more frequent and more dangerous. The sensor was fabricated using carbon paste modified with the inorganic complex chloro-5,10,15,20-tetrakis-(pentafluorophenyl)-21 H,23 H-porphyrin iron(III) (FeTPPCl); this metallic complex has a chemical core structure similar to the heme cofactor of the cytochrome P450 (CYPs). Measurements were performed with square-wave voltammetry. Using the optimised voltammetric parameters and without any sample preparation, the sensor showed a limit of detection of 2.8 mg L^?1 (14 μmol L^?1), recoveries ca. 102%, suitable selectivity and long durability (over 1 month).     

Global chaotic parameters of heart rate variability during mental task

We aimed to evaluate the novel chaotic global techniques of heart rate variability (HRV) analysis during a specific autonomic test, the mental arithmetic overload test. These are spectral detrended fluctuation analysis and spectral multi‐taper method; in addition to spectral entropy. We analyzed 24 healthy male students—all nonsmokers, aged between 18 and 22 years old. HRV was analyzed in the following periods: control protocol—the 10‐min periods before the performance of the task and the 5‐min periods during the performance of the test. Following tests for normality; Kruskal–Wallis technique and principal component analysis—it was decided that this type of mental stimulation did not lead to significant changes in any of the seven combinations of chaotic globals. In conclusion, it was suggested that the time‐series be increased to 1000 RR intervals (at least 20 min of electrocardiographic data) and standard nonlinear methods be introduced in combination with spectral factors as a way of increasing the statistical significance. © 2015 Wiley Periodicals, Inc. Complexity 21: 300–307, 2016