Minimal forbidden subwords

Motivated by a study of similar problems stated for factors of words, we study forbidden subwords of a language or a word. A procedure for obtaining the set of all words avoiding a given set of subwords is presented. On the other hand, an algorithm for computing the set of minimal forbidden subwords for a word is given. The case of a two-letter alphabet appears to be particularly interesting and it is considered separately.     

Pretreatment of Highly Polluted Pharmaceutical Waste Broth by Wet Air Oxidation

The preoxidation of a highly polluted waste pharmaceutical fermentation broth using wet air oxidation (WAO) has been studied as a possible method for the effective removal of organics. The applied (pre)treatment method should enhance the biotreatability of the pharmaceutical fermentation broth in terms of reduced initial toxicity and higher biodegradability. Preliminary experiments in the pilot biological treatment plant were successful only at low organic loads, whereas the system collapses at higher ones. The characterization of the fermentation broth was started by common physicochemical analysis, whereas several bioassays were used to determine its impact on biological treatment plants and the environment. Toxicity prior to and after WAO was determined using the acute Vibrio fischeri test, measurement of inhibition of O2 consumption, and the Daphnia magna acute test. Ready biodegradability of the treated and untreated broth has also been assessed. WAO experiments were accomplished in the 2?L batch reactor at different temperatures (240/280°C) and operating pressures. WAO experiments confirmed reduction of the toxicity toward microorganisms, whereas oxidized wastewater was more toxic to daphnids. Biodegradability of the oxidized broth has also been enhanced. Further work has been focused on designing appropriate combination of WAO and biological processes.     

Effect of low‐temperature plasma and chitosan treatment on wool dyeing with Acid Red 27

This study examines in detail the influence of low‐temperature plasma and biopolymer chitosan treatments on wool dyeability. Wool knitted fabrics were treated and characterized by whiteness and shrink‐resistance measurements. Surface modification was assessed by contact‐angle measurements of human hair fibers, which were used as a model to study the wetting properties of the treated wool knitted fabrics. The dyeing behavior was assessed from the diffusion mechanism point of view. The dyeing kinetics were measured at two different pHs (4.2 and 6.5) and three different temperatures (60, 85, and 100°C) to gain information about the contribution of the surface modification treatment to the dyeing mechanism. The exhaustion and reflectance data were compared, and the apparent diffusion coefficients were calculated. On the basis of the obtained results, a model for the dyeing mechanism of the chitosan treated wool was proposed. When treated with chitosan, the polymer sheath spread on the surface of the fibers acted as a predominant dyeing site in very short dyeing times, thus interacting with the dye and in later stages imparting the dye to the wool fiber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2204–2214, 2005     

Characterization of bimetallic NaY-supported Pt-Pd catalyst by EXAFS,TEM and TPR

NaY-supported bimetallic Pt-Pd catalysts have been studied by TEM, TPR and EXAFS. Small, randomly mixed particles are formed in the zeolite cages. When the Pt content is increased, a Pt core structure appears and the dispersion increases. Particle diameters are about 1–2 nm for bimetallic samples.     

Low-frequency quadrature mode birdcage resonator

The birdcage resonator is frequently used in conventional MRI because of its excellent attributes. Its use in low-field MRI is restricted to field strengths higher than, for example, 0.1 T, dependent on the size of the coil. This is because of the intrinsically low inductance value of the birdcage coils. Furthermore, the sensitivity of the birdcage at low field strengths is significantly lower when compared to, for example, the solenoid. Both problems can be overcome with the multiturn technique and a novel wound birdcage coil. The quadrature mode wound birdcage coil presented in this paper can be used at frequencies as low as 100 kHz. Its sensitivity is also increased when compared to the conventional strip-ring birdcage. Homogeneity effective volume, and methods to increase the resonator bandwidth to match the signal bandwidth are left intact. The latter is a typical low-field problem.     

Design of an Ultrafast G Protein Switch Based on a Mouse Melanopsin Variant

The primary goal of optogenetics is the light-controlled noninvasive and specific manipulation of various cellular processes. Herein, we present a hybrid strategy for targeted protein engineering combining computational techniques with electrophysiological and UV/visible spectroscopic experiments. We validated our concept for channelrhodopsin-2 and applied it to modify the less-well-studied vertebrate opsin melanopsin. Melanopsin is a promising optogenetic tool that functions as a selective molecular light switch for G protein-coupled receptor pathways. Thus, we constructed a model of the melanopsin G_q protein complex and predicted an absorption maximum shift of the Y211F variant. This variant displays a narrow blue-shifted action spectrum and twofold faster deactivation kinetics compared to wild-type melanopsin on G protein-coupled inward rectifying K⁺ (GIRK) channels in HEK293 cells. Furthermore, we verified the in vivo activity and optogenetic potential for the variant in mice. Thus, we propose that our developed concept will be generally applicable to designing optogenetic tools.     

The Effect of Titanium, Zirconium and Tin on the Growth of Diatom Synedra Acus and Morphology of Its Silica Valves

The effect of three Group IV metals (titanium, zirconium and tin) on the growth, morphology and chemical composition of the freshwater diatom Synedra acus subsp. radians (Kützing) Skabichevsky was studied and compared with germanium. The elements in their highest oxidation states were introduced into the culture medium in the form of hydroxides. Germanium was found to be toxic at ??5?mol. % of the total Ge-Si content in the culture medium. In the presence of other elements, a slight decrease in the cell division rate was observed independent of the element within 1?C15% content interval. The analysis of the obtained biomass and silica valves revealed the presence of all the added elements within the cells. However, only germanium was incorporated into the valves in considerable amounts. S. acus cultivation with the addition of 5% Group IV elements resulted in cells having the following aberrations in the structure of the silica valves: changes in valve shape, thickening of valves, alterations of the areolae rows, irregularity or absence of the areolae and a decrease in the mechanical strength of valves. Moreover, the effect of Group IV elements on silica formation was simulated in vitro using a synthetic polymer bearing polyamine and phosphate groups found in silaffines (proteins from diatom frustules). The studied elements were observed to provoke the formation of unstable silica particles in solution. We propose that the observed effects of germanium, titanium, zirconium and tin on diatom growth and structure are due to uncontrollable silica condensation.     

Energetically optimal running requires torques about the centre of mass

Bipedal animals experience ground reaction forces (GRFs) that pass close to the centre of mass (CoM) throughout stance, first decelerating the body, then re-accelerating it during the second half of stance. This results in fluctuations in kinetic energy, requiring mechanical work from the muscles. However, here we show analytically that, in extreme cases (with a very large body pitch moment of inertia), continuous alignment of the GRF through the CoM requires greater mechanical work than a maintained vertical force; we show numerically that GRFs passing between CoM and vertical throughout stance are energetically favourable under realistic conditions; and demonstrate that the magnitude, if not the precise form, of actual CoM-torque profiles in running is broadly consistent with simple mechanical work minimization for humans with appropriate pitch moment of inertia. While the potential energetic savings of CoM-torque support strategies are small (a few per cent) over the range of human running, their importance increases dramatically at high speeds and stance angles. Fast, compliant runners or hoppers would benefit considerably from GRFs more vertical than the zero-CoM-torque strategy, especially with bodies of high pitch moment of inertia—suggesting a novel advantage to kangaroos of their peculiar long-head/long-tail structure.