Generating Signals with Multiscale Time Irreversibility: The Asymmetric Weierstrass Function

Time irreversibility (asymmetry with respect to time reversal) is an important property of many time series derived from processes in nature. Some time series (e.g., healthy heart rate dynamics) demonstrate even more complex, multiscale irreversibility, such that not only the original but also coarse-grained time series are asymmetric over a wide range of scales. Several indices to quantify multiscale asymmetry have been introduced. However, there has been no simple generator of model time series with "tunable" multiscale asymmetry to test such indices. We introduce an asymmetric Weierstrass function W(A) (constructed from asymmetric sawtooth functions instead of cosine waves) that can be used to construct time series with any given value of the multiscale asymmetry. We show that multiscale asymmetry appears to be independent of other multiscale complexity indices, such as fractal dimension and multiscale entropy. We further generalize the concept of multiscale asymmetry by introducing time-dependent (local) multiscale asymmetry and provide examples of such time series. The W(A) function combines two essential features of complex fluctuations, namely fractality (self-similarity) and irreversibility (multiscale time asymmetry); moreover, each of these features can be tuned independently. The proposed family of functions can be used to compare and refine multiscale measures of time series asymmetry.     

UV/TiO2 Photocatalytic Degradation of Xanthene Dyes

UV/titanium dioxide (TiO₂) degradation of two xanthene dyes, erythrosine B (Ery) and eosin Y (Eos), was studied in a photocatalytic reactor. Photocatalysis was able to degrade 98% of Ery and 73% of Eos and led to 65% of chemical oxygen demand removal. Experiments in buffered solutions at different initial pH values reveal the pH dependence of the process, with better results obtained under acidic conditions due to the electrostatic attraction caused by the opposite charges of TiO₂ (positive) and of anionic dyes (negative). Batch activity tests under methanogenic conditions showed the high toxicity exerted by the dyes even at low concentrations (~85% with initial concentration of 0.3 mmol L^?1), but the end products of photocatalytic treatment were much less toxic toward methanogenic bacteria, as detoxification of 85 ± 5% for Eos and 64 ± 7% for Ery were obtained. In contrast, the dyes had no inhibitory effect on the biogenic‐carbon biodegradation activity of aerobic biomass, obtained by respirometry. The results demonstrate that photocatalysis combining UV/TiO₂ as a pretreatment followed by an anaerobic biological process may be promising for the treatment of wastewaters produced by many industries.     

Molecular motions in amorphous ibuprofen as studied by broadband dielectric spectroscopy

The molecular mobility of amorphous ibuprofen has been investigated by broadband dielectric relaxation spectroscopy (DRS) covering a temperature range of more than 200 K. Four different relaxation processes, labeled as alpha, beta, gamma, and D, were detected and characterized, and a complete relaxation map was given for the first time. The gamma-process has activation energy E a = 31 kJ.mol (-1), typical for local mobility. The weak beta-relaxation, observed in the glassy state as well as in the supercooled state was identified as the genuine Johari-Goldstein process. The temperature dependence of the relaxation time of the alpha-process (dynamic glass transition) does not obey a single VFTH law. Instead two VFTH regimes are observed separated by a crossover temperature, T B = 265 K. From the low temperature VFTH regime, a T g (diel) (tau =100 s) = 226 K was estimated, and a fragility or steepness index m = 93, was calculated showing that ibuprofen is a fragile glass former. The D-process has a Debye-like relaxation function but the temperature dependence of relaxation time also follows the VFTH behavior, with a Vogel temperature and a pre-exponential factor which seem to indicate that its dynamics is governed by the alpha-process. It has similar features as the Debye-type process observed in a variety of associating liquids, related to hydrogen bonding dynamics. The strong tendency of ibuprofen to form hydrogen bonded aggregates such as dimers and trimers either cyclic or linear which seems to control in particular the molecular mobility of ibuprofen was confirmed by IR spectroscopy, electrospray ionization mass spectrometry, and MD simulations.     

A New Chalcone Derivative with Promising Antiproliferative and Anti-Invasion Activities in Glioblastoma Cells

Glioblastoma (GBM) is the most common and most deadly primary malignant brain tumor. Current therapies are not effective, the average survival of GBM patients after diagnosis being limited to few months. Therefore, the discovery of new treatments for this highly aggressive brain cancer is urgently needed. Chalcones are synthetic and naturally occurring compounds that have been widely investigated as anticancer agents. In this work, three chalcone derivatives were tested regarding their inhibitory activity and selectivity towards GBM cell lines (human and mouse) and a non-cancerous mouse brain cell line. The chalcone 1 showed the most potent and selective cytotoxic effects in the GBM cell lines, being further investigated regarding its ability to reduce critical hallmark features of GBM and to induce apoptosis and cell cycle arrest. This derivative showed to successfully reduce the invasion and proliferation capacity of tumor cells, both key targets for cancer treatment. Moreover, to overcome potential systemic side effects and its poor water solubility, this compound was encapsulated into liposomes. Therapeutic concentrations were incorporated retaining the potent in vitro growth inhibitory effect of the selected compound. In conclusion, our results demonstrated that this new formulation can be a promising starting point for the discovery of new and more effective drug treatments for GBM.     

Development and validation of a stability-indicating LC method for the assay of lodenafil carbonate in tablets

A stability-indicating liquid chromatographic method has been developed for the quantitative determination of lodenafil carbonate in tablets. The method employs a Synergi Fusion C18 column (250 × 4.6 mm, i.d., 4 μm particle size), with mobile phase consisting of a mixture of methanol-acetic acid 0.1% pH 4.0 (65:35, v/v) and UV detection at 290 nm, using a photodiode array detector. A linear response (r = 0.9999) was observed in the range of 10-80 μg/mL. The method showed good recoveries (average 100.3%) and also intra and inter-day precision (RSD < 2.0%). Validation parameters as specificity and robustness were also determined. Specificity analysis showed that no impurities or degradation products were co-eluting with the lodenafil carbonate peak. The method was found to be stability-indicating and due to its simplicity and accuracy can be applied for routine quality control analysis of lodenafil carbonate in tablets.     

Non-isothermal crystallization of PVDF/PMMA blends processed in low and high shear mixers

The morphological, thermal and non-isothermal crystallization behavior of poly(vinylidene fluoride) (PVDF) and its blends with poly(methyl methacrylate) (PMMA) processed in low (LSM) and high (HSM) shear mixers were studied by differential scanning calorimetry (DSC). The processing effect on the PVDF melt and crystallization kinetics was described and the effect of PMMA on the PVDF crystallization was also investigated. The addition of PMMA into PVDF increases of relative B phase content independent of the processing conditions. The validity of the modified Avrami and Kolmogorov–Johnson–Mehl–Avrami (KJMA) models for the non-isothermal crystallization of PVDF/PMMA blends are discussed. The KJMA method described accurately the non-isothermal crystallization behavior. The results showed a shift in the PVDF crystallization/fusion peak to lower temperatures. The activation energies for crystallization of PVDF and its blends evaluated through the isoconversional method using Friedman's approximation were higher for samples processed in the LSM. Differences in the activation energies were related to the ability of the molecular segments to crystallize when reaching the growing crystallization front, confirming that the mixing process has some effect on the interaction between the polymers. On the other hand, the isoconversional methods in combination with the KJMA equation provide better understanding of the kinetics of the crystallization process demonstrated by a strongly dependence of activation energy (Ea), relative crystalline fraction (XT), and global and local Avrami exponents (n and n (XT)).     

Difructose anhydride-forming bacterial inulinase II and fructogenic fungal inulinase I

The reserve polymeric inulin from dahlia tuber (>12% or >60% yield, wet or dry basis, respectively) follows as an attractive source for both free fructose or difructofuranose anhydride (DFA III). Although DFA biological activity is not completely understood, there is interest in characterizing other DFA III-producers besidesArthrobacter ureafaciens. The inulinolytic bacterial isolate named “YLW,” owing to the yellow hue in agar slants, is such a producer. Its biochemical characterization showed the presence of galactosylated and mannosylated glycolipids associated with the bacterial cells. Immobilization of fungal inulinase I and bacterial inulinase II, the respective enzymatic catalysts for the production of fructose and DFA III by inulin hydrolysis, was attempted using controlled-pore silica (CPS). The effects of pH, temperature, and incubation time was analyzed and compared for both enzymes in the free and immobilized forms.

     

PCR protocol- and inulin catabolism-based differentiation of inulinolytic soil bacteria

Applied Biochemistry and Biotechnology - Bacteria collected from rotting dahlia tubers, instead of degrading inulin to D-fructose, preferentially formed the known DFA III (Β-2.1′:...     

Microbial inulinase secretion using chemically modified inulins

Applied Biochemistry and Biotechnology - Caproyl and cholesteryl derivatives of native dahlia inulin were prepared from the respective chloride donors, and the light derivatization was monitored...     

Screening ofBothrops snake venoms forl-amino acid oxidase activity

Applied Biochemistry and Biotechnology - Toxins, enzymes, and biologically active peptides are the main components of snake venoms from the genusBothrops. Following the venom inoculation, the local...