Application of chemometric methods in modeling of competitive multidye biosorption from ternary system

Simultaneous biosorption properties of three cationic dyes (Methylene blue, Crystal violet and Safranin) on Sargassum glaucescens were studied. In the most of previous papers in the field of dye biosorption, one dye or dyes with nearly separate spectra were used and dye concentration was determined by Beer’s law at different λ _max. Significant of this study is application of dyes with highly overlapped spectra (as many real situations) that their concentrations can be determined by chemometric methods. Plackett–Burman design was applied to identify the most significant factors, Box–Behnken design was used to determine optimal conditions, and principal component-wavelet neural network was used for the simultaneous determination of dye concentrations in ternary solutions. The optimum biosorption conditions were determined as dye concentration 10^?4 mol L^?1, biosorbent dosage 0.1 g L^?1 and biosorbent particle size 0.188 µm. At this condition, maximum biosorption capacity was 0.80 mmol g^?1. The biosorption process was slightly slower in the ternary system comparing with single system which was related to competition phenomena between dyes. It was found that the overall biosorption data were described by the pseudo-second-order kinetic model. Fourteen isotherm models were applied to experimental data, and it was concluded that Hill model had the best correlation.     

Path-kipas Ramsey numbers

For two given graphs F and H, the Ramsey number R(F,H) is the smallest positive integer p such that for every graph G on p vertices the following holds: either G contains F as a subgraph or the complement of G contains H as a subgraph. In this paper, we study the Ramsey numbers , where P_n is a path on n vertices and is the graph obtained from the join of K₁ and P_m. We determine the exact values of for the following values of n and m: 1?n?5 and m?3; n?6 and (m is odd, 3?m?2n-1) or (m is even, 4?m?n+1); 6?n≤7 and m=2n-2 or m?2n; n?8 and m=2n-2 or m=2n or (q·n-2q+1?m?q·n-q+2 with 3?q?n-5) or m?(n-3)²; odd n?9 and (q·n-3q+1?m?q·n-2q with 3?q?(n-3)/2) or (q·n-q-n+4?m?q·n-2q with (n-1)/2?q?n-4). Moreover, we give lower bounds and upper bounds for for the other values of m and n.     

beta-NMR of isolated lithium in nearly ferromagnetic palladium

The temperature dependence of the frequency shift and spin-lattice relaxation rate of isolated, nonmagnetic (8)Li impurities implanted in a nearly ferromagnetic host (Pd) are measured by means of beta-detected nuclear magnetic resonance (beta-NMR). The shift is negative, very large, and increases monotonically with decreasing T in proportion to the bulk susceptibility of Pd for T > T* approximately 100 K. Below T*, an additional shift occurs which we attribute to the response of Pd to the defect. The relaxation rate is much slower than expected for the large shift and is linear with T below T*, showing no sign of additional relaxation mechanisms associated with the defect.     

Synthesis of novel steroidal oxazolo quinoxaline as antibacterial agents

Steroidal[oxazolo(4,5-b)quinoxaline-2-yl-hydrazone] derivative (7a–9a) (7b–9b) were prepared by the multi-step reactions of steroid. It is prepared via the reaction of steroidal semicarbazones with 2,3-dichloroquinoxaline at 80 °C in ethanol. The structures of the compounds were evident by IR, ¹H NMR and mass spectrometry and their purities were confirmed by elemental analyses. The antibacterial activity of these compounds was evaluated by the disk diffusion assay against two Gram-positive and two Gram-negative bacteria and then the minimum inhibitory concentration (MIC) of compounds was determined. The results showed that compounds (7a, 7b, 8a, 8b) are better antibacterial agent as compared with the standard drug amoxicillin.     

Nigella sativa extract as a potent antioxidant for petrochemical-induced oxidative stress

Various beneficial properties has been attributed to Nigella sativa, including its antioxidant potential. Previously, it was reported that supercritical fluid extraction (SFE) could be used to obtain N. sativa extract rich in antioxidants. In the present study, N. sativa extracts prepared using the previously optimized SFE as well as the traditional Soxhlet extraction approaches were analyzed for various known antioxidants. N. sativa extracts were found to prevent protein carbonyl formation as well as depletion of intracellular glutathione (GSH) in fibroblasts exposed to toluene. Furthermore, partially purified SFE and Soxhlet fractions could prevent loss of hepatic GSH in toluene-induced oxidative stressed Wistar rats as well as in L929 fibroblasts. The results showed that SFE-produced N. sativa extract is richer in antioxidants than the Soxhlet approach. It was also shown using preparative silica gel and reverse phase chromatography that different fractions of SFE-extracted or Soxhlet-extracted N. sativa had different levels of protective effects with regards to GSH depletion in vivo as well as in cell culture. Although fractions rich in thymoquinone were found to be most potent in terms of antioxidant capacity, the data indicates that the protective effects of N. sativa may not only be due to thymoquinone, but perhaps other antioxidants.     

Investigation of structure, vibrational and NMR spectra of oxycodone and naltrexone: a combined experimental and theoretical study

In this work, two important opioid antagonists, naltrexone and oxycodone, were prepared from thebaine and were characterized by IR, (1)H NMR and (13)C NMR spectroscopy. Moreover, computational NMR and IR parameters were obtained using density functional theory (DFT) at B3LYP/6-311++G** level of theory. Complete NMR and vibrational assignment were carried out using the observed and calculated spectra. The IR frequencies and NMR chemical shifts, determined experimentally, were compared with those obtained theoretically from DFT calculations, showed good agreements. The RMS errors observed between experimental and calculated data for the IR absorptions are 85 and 105 cm(-1), for the (1)H NMR peaks are 0.87 and 0.17 ppm and for those of (13)C NMR are 5.6 and 5.3 ppm, respectively for naltrexone and oxycodone.     

Tautomerism in Salicylidene Benzylamine

The UV spectra of substituted salicylidene benzylamine schiff bases were studied in four solvents. It was found that substituents which increase the electronic effect and not the steric compression effect in these compounds increase the percentage of the keto form. The intensity (i.e. % keto) of the keto band which occurs at > 400 nm in the UV spectra increases in polar solvents.     

Development of a Dewaxing Protocol for Tissue-Engineered Models of the Oral Mucosa Used for Raman Spectroscopic Analysis

Abstract: We demonstrate that wax-embedded models of tissue-engineered oral mucosa can be effectively dewaxed using xylene for Raman spectroscopic analysis. Tissue sections of 20 μm thickness were cut and mounted onto glass slides. Sections were placed in xylene for increasing lengths from 2 to 45 min. Acquired Raman spectra revealed the wax contribution in the fingerprint region until 28-min treatment in xylene. Good quality and wax-free spectra were recorded at 30, 35, 40, and 45 min in xylene with no significant differences among them. It is essential to collect uncontaminated Raman spectra in order to achieve authentic results because the fingerprint region of biological tissues holds extremely vital information that is of diagnostic significance in cancer.     

Detection of explosives and latent fingerprint residues utilizing laser pointer–based Raman spectroscopy

A modular, compact Raman spectrometer, based on a green laser pointer, an air cooled intensified charged coupled device and a x, y motorized translation stage was developed and applied for point detection. Its performance was tested for measurements of Raman spectra of liquids, trace amounts of explosives and individual particles, as well as for locating individual particles of interest and for chemical imaging of residues of latent human fingerprints. This system was found to be highly sensitive, identifying masses as low as ~1 ng in short times. The point and real-time detection capabilities of the spectrometer, together with the portability that it offers, make it a potential candidate for replacing existing Raman microscopes and for field applications.     

Hodge Structures Associated to SU(p, 1)

Let A be an abelian variety over ? such that the semisimple part of the Hodge group of A is a product of copies of SU(p, 1) for some p > 1. We show that any effective Tate twist of a Hodge structure occurring in the cohomology of A is isomorphic to a Hodge structure in the cohomology of some abelian variety.