Showing papers by "Wrocław University of Technology published in 2015"
TL;DR: In this paper, a review compiles the work conducted by various researchers over the last few decades on the use of various agricultural waste peels as adsorbents for the water and wastewater treatment.
570 citations
15 Jul 2015-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: The microstructural and mechanical properties of Inconel 718 were determined on the specimens manufactured by selective laser melting (SLM) of prealloyed powder as mentioned in this paper, showing that columnar grains of supersaturated solid solution with internal microsegregation of Nb and Mo, demonstrated by fractions of Laves eutectic or its divorced form in interdendritic regions.
Abstract: The microstructural and mechanical properties of Inconel 718 were determined on the specimens manufactured by selective laser melting (SLM) of prealloyed powder. High- density (99.8%) cylindrical specimens were built with four orientations (0°, 45°, 45°×45° and 90°) in relation to the building and scanning directions. Because of directional, dendritic-cellular grain growth, microstructure of the as-built specimens was characterized by columnar grains of supersaturated solid solution with internal microsegregation of Nb and Mo, demonstrated by fractions of Laves eutectic or its divorced form in interdendritic regions. Such a heterogeneous microstructure is unsuitable for direct post-process aging and makes the alloy sensitive to subsolidus liquation during rapid heating to the homogenizing temperature. In homogenized and aged condition, the alloy received a very good set of mechanical properties in comparison with the wrought material. In heat-treated condition, like in as-built condition, weak anisotropy of properties was found, manifested by lower Young's modulus, yield strength and tensile strength of the specimens extended along the build direction in comparison to the values for the other variants of the specimens. This is attributed to the fact that the grains maintained their geometric and crystallographic texture obtained during solidification.
512 citations
TL;DR: The properties of biologically active compounds extracted from the biomass of algae reported in the literature are presented in a structured way and a list of applications of algal extracts in different developing branches of agriculture (biostimulants, bioregulators, feed additives) and in pharmaceutical industry is assembled.
Abstract: Algal extracts are gaining increasing interest due to their unique composition and possibilities of wide industrial applications. Various extraction techniques are used for conversion of algal biomass into extracts. Recently, attention of scientists has been paid to novel methods, such as enzyme-assisted extraction, microwave-assisted extraction, pressurized liquid extraction, supercritical fluid extraction, and ultrasound-assisted extraction, which enable the extraction of biologically active compounds without their degradation. In this review, the properties of biologically active compounds extracted from the biomass of algae reported in the literature are presented in a structured way. Algal extracts contain compounds such as carbohydrates, proteins, minerals, oil, fats, polyunsaturated fatty acids as well as bioactive compounds such as antioxidants (polyphenols, tocopherols [vitamin E], vitamin C, mycosporine-like amino acids), and pigments, such as carotenoids (carotene xanthophyll), chlorophylls, and phycobilins (phycocyanin, phycoerythrin), which possess antibacterial, antiviral, antifungal, antioxidative, anti-inflammatory, and antitumor properties. Finally, we assemble a list of applications of algal extracts in different developing branches of agriculture (biostimulants, bioregulators, feed additives) and in pharmaceutical industry.
354 citations
TL;DR: It is experimentally shown that BP exhibits saturable absorption in the 2 μm wavelength range and supports ultrashort pulse generation and might be considered as a universal broadband saturable absorber that could successfully compete with graphene or other low-dimension nanomaterials.
Abstract: We report, for the first time to our knowledge, the usage of black phosphorus (BP) as a saturable absorber for the mode locking of a thulium-doped fiber laser. We have experimentally shown that BP exhibits saturable absorption in the 2 μm wavelength range and supports ultrashort pulse generation. The saturable absorber was based on mechanically exfoliated BP deposited on a fiber connector tip. The laser was capable of generating 739 fs pulses centered at 1910 nm. Our results show that BP might be considered as a universal broadband saturable absorber that could successfully compete with graphene or other low-dimension nanomaterials.
318 citations
TL;DR: SLOPE as mentioned in this paper is the solution to the sorted L-one penalized estimator, where the regularizer is a sorted l1 norm, which penalizes the regression coefficients according to their rank: the higher the rank, stronger the signal, the larger the penalty.
Abstract: We introduce a new estimator for the vector of coefficients β in the linear model y = Xβ + z, where X has dimensions n × p with p possibly larger than n. SLOPE, short for Sorted L-One Penalized Estimation, is the solution to [Formula: see text]where λ1 ≥ λ2 ≥ … ≥ λ p ≥ 0 and [Formula: see text] are the decreasing absolute values of the entries of b. This is a convex program and we demonstrate a solution algorithm whose computational complexity is roughly comparable to that of classical l1 procedures such as the Lasso. Here, the regularizer is a sorted l1 norm, which penalizes the regression coefficients according to their rank: the higher the rank-that is, stronger the signal-the larger the penalty. This is similar to the Benjamini and Hochberg [J. Roy. Statist. Soc. Ser. B57 (1995) 289-300] procedure (BH) which compares more significant p-values with more stringent thresholds. One notable choice of the sequence {λ i } is given by the BH critical values [Formula: see text], where q ∈ (0, 1) and z(α) is the quantile of a standard normal distribution. SLOPE aims to provide finite sample guarantees on the selected model; of special interest is the false discovery rate (FDR), defined as the expected proportion of irrelevant regressors among all selected predictors. Under orthogonal designs, SLOPE with λBH provably controls FDR at level q. Moreover, it also appears to have appreciable inferential properties under more general designs X while having substantial power, as demonstrated in a series of experiments running on both simulated and real data.
303 citations
TL;DR: In this article, the authors demonstrate that black phosphorus can serve as a broadband saturable absorber and can be used for ultrashort optical pulse generation with performances similar or even better than currently used graphene or carbon nanotubes.
Abstract: Low-dimensional materials, due to their unique and versatile properties, are very interesting for numerous applications in electronics and optoelectronics. Recently rediscovered black phosphorus, with a graphite-like layered structure, can be effectively exfoliated up to the single atomic layer called phosphorene. Contrary to graphene, it possesses a direct band gap controllable by the number of stacked atomic layers. For those reasons, black phosphorus is now intensively investigated and can complement or replace graphene in various photonics and electronics applications. Here, we demonstrate that black phosphorus can serve as a broadband saturable absorber and can be used for ultrashort optical pulse generation. The mechanically exfoliated ∼300 nm thick layers of black phosphorus were transferred onto the fiber core, and under pulsed excitation at 1560 nm wavelength, its transmission increases by 4.6%. We have demonstrated that the saturable absorption of black phosphorus is polarization sensitive. The fabricated device was used to mode-lock an Er-doped fiber laser. The generated optical solitons with the 10.2 nm bandwidth and 272 fs duration were centered at 1550 nm. The obtained results unambiguously show that black phosphorus can be effectively used for ultrashort pulse generation with performances similar or even better than currently used graphene or carbon nanotubes. This application of black phosphorus proves its great potential to future practical use in photonics.
288 citations
TL;DR: In this paper, a broadband saturable absorber of black phosphorus was used for ultrashort optical pulse generation, where the mechanically exfoliated ~300 nm thick layers were transferred onto the fiber core and under pulsed excitation at 1560 nm wavelength its transmission increases by 4.4%.
Abstract: Low-dimensional materials, due to their versatile properties are very interesting for numerous electronics and optoelectronics applications. Recently rediscovered black phosphorus, with a graphite-like structure can be exfoliated up to the single atomic layer. In contrary to graphene it possesses a direct band gap controllable by the number of stacked atomic layers. For those reasons, it is now intensively investigated. Here we demonstrate, that black phosphorus can serve as a broadband saturable absorber and can be used for ultrashort optical pulse generation. The mechanically exfoliated ~300 nm thick layers of black phosphorus were transferred onto the fiber core and under pulsed excitation at 1560 nm wavelength its transmission increases by 4.4%. It was used to generate 272 fs-short pulses at 1550 nm and 739 fs at 1910 nm. The obtained results shows that black phosphorus can be effectively used for ultrashort pulse generation and proves its great potential to future applications.
241 citations
TL;DR: A review of techniques used for ABE recovery, such as distillation, adsorption, gas stripping, liquid-liquid extraction, pertraction, membrane distillation and sweeping gas pervaporation, thermopervaporation and vacuum pervapsoration, can be found in this paper.
Abstract: Butanol has a great potential as a biofuel and to date a lot of research has been done both in terms of more efficient butanol production as well as in developing product recovery methods. Many of them deal with separation techniques which can be used for selective recovery of acetone, n-butanol and ethanol from model solutions and fermentation broths. This work is a review of techniques used for ABE recovery, such as distillation, adsorption, gas stripping, liquid–liquid extraction, pertraction, membrane distillation, sweeping gas pervaporation, thermopervaporation and vacuum pervaporation. Advantages and disadvantages of using particular methods, examples of applications and integrated processes are also described.
216 citations
TL;DR: It is found that the mammalian-host response to infecting bacteria causes the concomitant removal of phage from the system, and a universal schema of innate and adaptive immunity impact on phage pharmacokinetics is proposed, based on the results of the numerical simulations.
Abstract: Emerging bacterial antibiotic resistance draws attention to bacteriophages as a therapeutic alternative to treat bacterial infection. Examples of phage that combat bacteria abound. However, despite careful testing of antibacterial activity in vitro, failures nevertheless commonly occur. We investigated immunological response of phage antibacterial potency in vivo. Anti-phage activity of phagocytes, antibodies, and serum complement were identified by direct testing and by high-resolution fluorescent microscopy. We accommodated the experimental data into a mathematical model. We propose a universal schema of innate and adaptive immunity impact on phage pharmacokinetics, based on the results of our numerical simulations. We found that the mammalian-host response to infecting bacteria causes the concomitant removal of phage from the system. We propose the notion that this effect as an indirect pathway of phage inhibition by bacteria with significant relevance for the clinical outcome of phage therapy.
182 citations
TL;DR: In this paper, two types of lignin obtained from softwood (LB) and hardwood (LO) were employed for manufacturing polylactic acid (PLA) based composites.
Abstract: Two types of lignin obtained from softwood (LB) and hardwood (LO) were employed for manufacturing polylactic acid (PLA) – based composites. The morphological changes, mechanical and thermal properties, as well as water uptake of composites were evaluated before and after accelerated weathering. The chemical structure of lignin has an important influence on the composite properties. The addition of lignins to PLA matrix determined an increase of the impact strength and thermal stability of PLA, a good adhesion being observed in SEM micrographs. After accelerated weathering, tensile and impact strength decreased for all samples, but slightly for PLA/lignin composites, while all composites recorded an increase of water sorption capacity, especially for PLA/LB material. The free surface energy increased after weathering for all materials. The obtained results offer an opportunity to design environmentally friendly materials containing lignin that present higher values than the raw material itself.
177 citations
TL;DR: A new class of point defects in single-layer transition metal dichalcogenides that can be created through 60° rotations of metal–chalcogen bonds in the trigonal prismatic lattice are reported, with the simplest among them being a three-fold symmetric trefoil-like defect.
Abstract: As defects frequently govern the properties of crystalline solids, the precise microscopic knowledge of defect atomic structure is of fundamental importance. We report a new class of point defects in single-layer transition metal dichalcogenides that can be created through 60° rotations of metal-chalcogen bonds in the trigonal prismatic lattice, with the simplest among them being a three-fold symmetric trefoil-like defect. The defects, which are inherently related to the crystal symmetry of transition metal dichalcogenides, can expand through sequential bond rotations, as evident from in situ scanning transmission electron microscopy experiments, and eventually form larger linear defects consisting of aligned 8-5-5-8 membered rings. First-principles calculations provide insights into the evolution of rotational defects and show that they give rise to p-type doping and local magnetic moments, but weakly affect mechanical characteristics of transition metal dichalcogenides. Thus, controllable introduction of rotational defects can be used to engineer the properties of these materials.
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TL;DR: In this paper, the authors proposed a probabilistic load forecasting method based on Quantile Regression Averaging (QRA) on a set of sister point forecasts, which can leverage the development in the point load forecasting literature over the past several decades.
Abstract: Majority of the load forecasting literature has been on point forecasting, which provides the expected value for each step throughout the forecast horizon. In the smart grid era, the electricity demand is more active and less predictable than ever before. As a result, probabilistic load forecasting, which provides additional information on the variability and uncertainty of future load values, is becoming of great importance to power systems planning and operations. This paper proposes a practical methodology to generate probabilistic load forecasts by performing Quantile Regression Averaging (QRA) on a set of sister point forecasts. There are two major benefits of the proposed approach: 1) it can leverage the development in the point load forecasting literature over the past several decades; and 2) it does not rely so much on high quality expert forecasts, which are rarely achievable in load forecasting practice. To demonstrate the effectiveness of the proposed approach and make the results reproducible to the load forecasting community, we construct a case study using the publicly available data from the Global Energy Forecasting Competition 2014. Comparing with the benchmark methods that utilize the variability of a selected individual forecast, the proposed approach leads to dominantly better performance as measured by the pinball loss function and the Winkler score.
TL;DR: An empirical evaluation in which several process metrics were investigated in order to identify the ones which significantly improve the defect prediction models based on product metrics, and it is reasonable to recommend the NDC process metric in building the defects prediction models.
Abstract: The knowledge about the software metrics which serve as defect indicators is vital for the efficient allocation of resources for quality assurance. It is the process metrics, although sometimes difficult to collect, which have recently become popular with regard to defect prediction. However, in order to identify rightly the process metrics which are actually worth collecting, we need the evidence validating their ability to improve the product metric-based defect prediction models. This paper presents an empirical evaluation in which several process metrics were investigated in order to identify the ones which significantly improve the defect prediction models based on product metrics. Data from a wide range of software projects (both, industrial and open source) were collected. The predictions of the models that use only product metrics (simple models) were compared with the predictions of the models which used product metrics, as well as one of the process metrics under scrutiny (advanced models). To decide whether the improvements were significant or not, statistical tests were performed and effect sizes were calculated. The advanced defect prediction models trained on a data set containing product metrics and additionally Number of Distinct Committers (NDC) were significantly better than the simple models without NDC, while the effect size was medium and the probability of superiority (PS) of the advanced models over simple ones was high ( $$p=.016$$ p = . 016 , $$r=-.29$$ r = - . 29 , $$\hbox {PS}=.76$$ PS = . 76 ), which is a substantial finding useful in defect prediction. A similar result with slightly smaller PS was achieved by the advanced models trained on a data set containing product metrics and additionally all of the investigated process metrics ( $$p=.038$$ p = . 038 , $$r=-.29$$ r = - . 29 , $$\hbox {PS}=.68$$ PS = . 68 ). The advanced models trained on a data set containing product metrics and additionally Number of Modified Lines (NML) were significantly better than the simple models without NML, but the effect size was small ( $$p=.038$$ p = . 038 , $$r=.06$$ r = . 06 ). Hence, it is reasonable to recommend the NDC process metric in building the defect prediction models.
TL;DR: In this paper, a high-pressure assisted hydrothermal treatment is proposed as a facile, green and efficient route for the reduction of aqueous dispersions of graphene oxide.
Abstract: A high-pressure assisted hydrothermal treatment is proposed as a facile, green and efficient route for the reduction of aqueous dispersions of graphene oxide. Reactions were performed in an autoclave at mild temperature (180 °C) using only water and nitrogen or hydrogen gas. No further separation or purification of the reduced products was required. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis revealed that the application of high pressure significantly enhanced oxygen removal. The C/O atomic ratio of the graphene oxide sheets increased from 1.65 to 5.29 upon conventional hydrothermal treatment using autogenous pressure. Higher C/O ratios of 6.35 and 7.93 were obtained for graphene oxides that were reduced under high-pressure of nitrogen and hydrogen, respectively. Specifically, the use of high-pressure hydrogen improved the removal of oxygen double-bonded to carbon. The introduction of covalently bonded heteroatoms, which is commonly observed for the use of reductants such as hydrazine, was not detected. Furthermore, high-pressure reduction led to a better restoration of the sp2 conjugation than was obtained by conventional hydrothermal treatment, as determined by XPS and Raman spectroscopies. These findings illustrate the promise of high-pressure hydrothermal treatments for the eco-friendly mass production of reduced graphene oxide.
TL;DR: This work attempts to extract practical guidelines for the estimation of anomalous time averaged MSDs through the simulation of multiple scenarios with fractional Brownian motion as a representative of a large class of fractional ergodic processes.
Abstract: Single particle tracking is an essential tool in the study of complex systems and biophysics and it is commonly analyzed by the time-averaged mean square displacement (MSD) of the diffusive trajectories. However, past work has shown that MSDs are susceptible to significant errors and biases, preventing the comparison and assessment of experimental studies. Here, we attempt to extract practical guidelines for the estimation of anomalous time averaged MSDs through the simulation of multiple scenarios with fractional Brownian motion as a representative of a large class of fractional ergodic processes. We extract the precision and accuracy of the fitted MSD for various anomalous exponents and measurement errors with respect to measurement length and maximum time lags. Based on the calculated precision maps, we present guidelines to improve accuracy in single particle studies. Importantly, we find that in some experimental conditions, the time averaged MSD should not be used as an estimator.
TL;DR: This paper reviews recent developments in the formation of polyelectrolyte oil-core nanocarriers by subsequent multilayer adsorption at micellar structures, their imaging, physical state and stability, drug encapsulation and applications, in vitro release profiles and in vitro biological evaluation.
TL;DR: While the empirical PI from combined forecasts do not provide significant gains, the QRA-based PI are found to be more accurate than those of the best individual model—the smoothed nonparametric autoregressive model.
Abstract: We examine possible accuracy gains from forecast averaging in the context of interval forecasts of electricity spot prices. First, we test whether constructing empirical prediction intervals (PI) from combined electricity spot price forecasts leads to better forecasts than those obtained from individual methods. Next, we propose a new method for constructing PI--Quantile Regression Averaging (QRA)--which utilizes the concept of quantile regression and a pool of point forecasts of individual (i.e. not combined) models. While the empirical PI from combined forecasts do not provide significant gains, the QRA-based PI are found to be more accurate than those of the best individual model--the smoothed nonparametric autoregressive model.
TL;DR: In this article, Wieslaw Strek et al. showed that the broadband emission is centred at 650 nm and has an intensity that is strongly influenced by the excitation laser power with a clear threshold.
Abstract: Graphene ceramics can have their band gaps opened and emit white light when excited by visible or infrared light, report scientists in Poland. Wieslaw Strek and co-workers from the Polish Academy of Sciences and Wroclaw University of Technology say that the broadband emission is centred at 650 nm and has an intensity that is strongly influenced by the excitation laser power with a clear threshold. Their analysis suggests that the origin of the emission is entirely electronic in nature and is not related to incandescence or blackbody radiation. White-light emission is observed for cryogenically cooled samples with temperatures as low as 10 K. The graphene ceramic was fabricated by placing graphene flakes in a calcium carbonate toroid and subjecting them to a high temperature (550 °C) and a pressure of 8 GPa for 1 min.
TL;DR: The present study provides new insight into the performance of linear-response CC2 and polarization-propagator ADC methods for molecular electronic spectroscopy and applications in computational photochemistry.
Abstract: As a minimal model of the chromophore of rhodopsin proteins, the penta-2,4-dieniminium cation (PSB3) poses a challenging test system for the assessment of electronic-structure methods for the exploration of ground- and excited-state potential-energy surfaces, the topography of conical intersections, and the dimensionality (topology) of the branching space. Herein, we report on the performance of the approximate linear-response coupled-cluster method of second order (CC2) and the algebraic-diagrammatic-construction scheme of the polarization propagator of second and third orders (ADC(2) and ADC(3)). For the ADC(2) method, we considered both the strict and extended variants (ADC(2)-s and ADC(2)-x). For both CC2 and ADC methods, we also tested the spin-component-scaled (SCS) and spin-opposite-scaled (SOS) variants. We have explored several ground- and excited-state reaction paths, a circular path centered around the S1/S0 surface crossing, and a 2D scan of the potential-energy surfaces along the branching sp...
TL;DR: In this paper, a low temperature hydrothermal method was used to grow zinc oxide nanorods (ZnONR) on a p-type silicon surface, where the thickness of the ZnO layer was optimized to increase the light-trapping effect and thus the photovoltaic response.
TL;DR: Synthetic applications of the oxidation reactions mediated by selenium(IV) oxide, areneseleninic acids, their anhydrides, selenides, diselenides, benzisoselenazol-3(2H)-ones and other less often used other organoselenium compounds are devoted.
Abstract: A variety of selenium compounds were proven to be useful reagents and catalysts for organic synthesis over the past several decades. The most interesting aspect, which emerged in recent years, concerns application of hydroperoxide/selenium(IV) oxide and hydroperoxide/organoselenium catalyst systems, as "green reagents" for the oxidation of different organic functional groups. The topic of oxidations catalyzed by organoselenium derivatives has rapidly expanded in the last fifteen years This paper is devoted to the synthetic applications of the oxidation reactions mediated by selenium compounds such as selenium(IV) oxide, areneseleninic acids, their anhydrides, selenides, diselenides, benzisoselenazol-3(2H)-ones and other less often used other organoselenium compounds. All these compounds have been successfully applied for various oxidations useful in practical organic syntheses such as epoxidation, 1,2-dihydroxylation, and α-oxyfunctionalization of alkenes, as well as for ring contraction of cycloalkanones, conversion of halomethyl, hydroxymethyl or active methylene groups into formyl groups, oxidation of carbonyl compounds into carboxylic acids and/or lactones, sulfides into sulfoxides, and secondary amines into nitrones and regeneration of parent carbonyl compounds from their azomethine derivatives. Other reactions such as dehydrogenation and aromatization, active carbon-carbon bond cleavage, oxidative amidation, bromolactonization and oxidation of bromide for subsequent reactions with alkenes are also successfully mediated by selenium (IV) oxide or organoselenium compounds. The oxidation mechanisms of ionic or free radical character depending on the substrate and oxidant are discussed. Coverage of the literature up to early 2015 is provided. Links have been made to reviews that summarize earlier literature and to the methods of preparation of organoselenium reagents and catalysts.
TL;DR: In this paper, a feed-forward neural network with a topology optimized by response surface methodology was applied successfully for prediction of biosorption performance for the removal of Cu 2+ ions by waste flax meal.
TL;DR: An email detection system that is designed based on an improvement in the negative selection algorithm and the proposed model with the best accuracy is used to differentiate between spam and non-spam in a network that is developed based on a client–server network for spam detection.
TL;DR: In this article, the metal-ligand cooperative properties of a bis-N-heterocyclic carbene ruthenium CNC pincer catalyst and its activity in CO2 hydrogenation to formates were studied by DFT calculations complemented by NMR spectroscopy.
Abstract: Metal–ligand cooperative properties of a bis-N-heterocyclic carbene ruthenium CNC pincer catalyst and its activity in CO2 hydrogenation to formates were studied by DFT calculations complemented by NMR spectroscopy and kinetic measurements. The dearomatized Ru–CNC* pincer (1*) is significantly more reactive toward metal–ligand cooperative activation of H2 and CO2 than the structurally related phosphine-based Ru–PNP complex. The enhanced reactivity of Ru–CNC* stems from the combination of electronic properties of this system and the reduced geometric constraints imposed onto the Ru center by the large and flexible CNC chelate. Heterolytic dissociation of H2 by 1* results in the bis-hydrido complex 2 that is active in hydrogenation of CO2. However, under commonly applied reaction conditions, the catalyst rapidly deactivates via metal–ligand cooperative paths. The transient formation of the dearomatized complex Ru–CNC* (1*) in the course of the reaction leads to the irreversible cooperative activation of CO2,...
TL;DR: In this article, the authors discuss the importance of diversity in the context of cyber bullying and cyber bullying, and propose a method to improve the safety of cyberbullying in cyber bullying.
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TL;DR: In this paper, a numerical study of heat and mass transfer in indirect evaporative air coolers with four air flow patterns: parallel flow, counter-flow, cross-flow and regenerative is presented.
TL;DR: In this paper, a mathematical simulation of heat and mass transfer in eight different types of the Maisotsenko Cycle (M-Cycle) heat-and mass exchangers (HMXs) used for indirect evaporative air cooling is presented.
01 Dec 2015
TL;DR: In this article, a hybrid ant colony optimization (HAntCO) approach in solving multi-skill resource-constrained project scheduling problem (MS-RCPSP) has been presented.
Abstract: In this paper, hybrid ant colony optimization (HAntCO) approach in solving multi-skill resource-constrained project scheduling problem (MS-RCPSP) has been presented. We have proposed hybrid approach that links classical heuristic priority rules for project scheduling with ant colony optimization (ACO). Furthermore, a novel approach for updating pheromone value has been proposed based on both the best and worst solutions stored by ants. The objective of this paper is to research the usability and robustness of ACO and its hybrids with priority rules in solving MS-RCPSP. Experiments have been performed using artificially created dataset instances based on real-world ones. We published those instances that can be used as a benchmark. Presented results show that ACO-based hybrid method is an efficient approach. More directed search process by hybrids makes this approach more stable and provides mostly better results than classical ACO.
TL;DR: In this paper, upper and lower estimates of densities of convolution semigroups of probability measures under explicit assumptions on the corresponding Levy measure and the Levy-Khinchin exponent are given.
TL;DR: Analysis of the data revealed that methanogens are able to grow from 0 to 122 °C, and there is no clear correlation between the optimal growth temperature and the DNA G+C content.
Abstract: The methanogenic archaea are a group of micro-organisms that have developed a unique metabolic pathway for obtaining energy. There are 150 characterized species in this group; however, novel species continue to be discovered. Since methanogens are considered a crucial part of the carbon cycle in the anaerobic ecosystem, characterization of these micro-organisms is important for understanding anaerobic ecology. A methanogens database (MDB; http://metanogen.biotech.uni.wroc.pl/), including physiological and biochemical characteristics of methanogens, was constructed based on the descriptions of isolated type strains. Analysis of the data revealed that methanogens are able to grow from 0 to 122 °C. Methanogens growing at the same temperature may have very different growth rates. There is no clear correlation between the optimal growth temperature and the DNA G+C content. The following substrate preferences are observed in the database: 74.5 % of archaea species utilize H2+CO2, 33 % utilize methyl compounds and 8.5 % utilize acetate. Utilization of methyl compounds (mainly micro-organisms belonging to the genera Methanosarcina and Methanolobus ) is seldom accompanied by an ability to utilize H2+CO2. Very often, data for described species are incomplete, especially substrate preferences. Additional research leading to completion of missing information and development of standards, especially for substrate utilization, would be very helpful.