bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of Concentration Polarization in a Reverse Osmosis Channel with Parabolic Crossflow
Authors: Liu Cui , Morse Audra , Rainwater Ken , Song Lianfa 
Published: January 2014

ABSTRACT: Concentration polarization in narrow reverse osmosis channels with parabolic crossflow was numerically simulated with finite different equations related to permeate velocity, crossflow velocity, average salt concentration, and wall salt concentration. A significant new theoretical development was the determination of two correction functions, F2 and F3, in the governing equation for average salt concentration. Simulations of concentration polarization under various conditions were then presented to describe the features of the new model as well as discussions about the differences of concentration polarizations of the more realistic parabolic flow with those when plug flow or shear flow was assumed. The situations in which the simpler models based on shear or plug flow can be used were indicated. Concentration polarization was also simulated for various conditions to show the applicability of the model and general features of concentration polarization in a narrow, long reverse osmosis channel.
Biopower Generation from Kitchen Wastewater Using a Bioreactor
Authors: Khan Abdul M. , Naz Shamsa 
Published: January 2014

ABSTRACT: This research provides a comparative study of the power output from mediator‐less and mediator microbial fuel cells (MFCs) under aerobic and partially anaerobic conditions using kitchen wastewater (KWW) as a renewable energy source. The wastewater sample was subjected to different physical, chemical, biochemical, and microbial analysis. The chemical oxygen demand (COD), biochemical oxygen demand (BOD), and power output values were greater for the fermented samples than the non‐fermented samples. The power output of samples was compared through the development of MFCs by using sand‐salt bridge and agar‐salt bridge. The H2 that was produced was converted to atomic hydrogen by using the nickel‐coated zinc electrode. In addition, the power output was further enhanced by introducing air into the cathodic chamber, where oxygen reacts with the protons to form pure H2O. The study showed that the power output was increased with the increase in COD and BOD values.
Lead Biosorption Using a Dairy Sludge—Thermodynamic Study and Competition Effects
Authors: Sassi M. , Guibal E. , Bestani B. 
Published: January 2014

ABSTRACT: Local diary sludge as a biosorbent was used in this study for lead ion adsorption from aqueous solution. Batch experiments were carried out as a function of temperature, initial concentration, and ionic strength. Lead uptake was significantly enhanced from 149 to 224 mg/g of dairy sludge by a temperature increase at pH 5. Equilibrium data for metal ion adsorption were analyzed using model equations, namely Langmuir and Freundlich isotherms, and the best fit to the experimental data was provided by the first isotherm model. Brunauer–Emett–Teller and Fourier transform infrared analyses were also performed to characterize the biosorbent. Ionic strength using NaCl, NaNO3, and Ca(NO3)2 did not affect Pb+2 sorption, while there was a 20% decrease using CaCl2. A limited effect of Cd+2 ions present in the binary system on lead sorption was observed. This study shows that this local dairy sludge can be an alternative to the commercially available adsorbents for the removal of heavy metals from liquid effluents.
An Investigation of Moving Bed Biofilm Reactor Nitrification during Long‐Term Exposure to Cold Temperatures
Authors: Hoang Valerie , Delatolla Robert , Laflamme Edith , Gadbois Alain 
Published: January 2014

ABSTRACT: Biological treatment is the most common and economical means of ammonia removal in wastewater; however, nitrification rates can become completely impeded at cold temperatures. Attached growth processes and, specifically, moving bed biofilm reactors (MBBRs) have shown promise with respect to low‐temperature nitrification. In this study, two laboratory MBBRs were used to investigate MBBR nitrification rates at 20, 5, and 1 °C. Furthermore, the solids detached by the MBBR reactors were investigated and Arrhenius temperature correction models used to predict nitrification rates after long‐term low‐temperature exposure was evaluated. The nitrification rate at 5 °C was 66 ± 3.9% and 64 ± 3.7% compared to the rate measured at 20 °C for reactors 1 and 2, respectively. The nitrification rates at 1 °C over a 4‐month exposure period compared to the rate at 20 °C were 18.7 ± 5.5% and 15.7 ± 4.7% for the two reactors. The quantity of solids detached from the MBBR biocarriers was low and the mass of biofilm per carrier did not vary significantly at 20 °C compared to that after long‐term exposure at 1 °C. Lastly, a temperature correction model based on exposure time to cold temperatures showed a strong correlation to the calculated ammonia removal rates relative to 20 °C following a gradual acclimatization period to cold temperatures.
Effectiveness of Phytoremediation Technologies to Clean Up of Metalloids Using Three Plant Species in Iran
Authors: Nejatzadeh‐Barandozi Fatemeh , Gholami‐Borujeni Fathollah. 
Published: January 2014

ABSTRACT: Phytoremediation is a potential, innovative, and cost‐effective technology for non‐destructive remediation of heavy‐metal contaminated soils. A field trial was conducted to evaluate the phytoremediation efficiencies of three plants and the effects of ethylenediaminetetraacetic acid (EDTA) or ammonium addition [(NH4)2SO4 and NH4NO3] for assisting removal of heavy metals (Pb, Hg, and Cd) from contaminated soil. The tested plants include Amaranthus retroflexus, Sorghum bicolor, and Lolium perrene. Results showed that maximum concentration of Pb, Hg, and Cd were detected in shoots of A. retroflexus, S. bicolor, and L. perrene at high concentrations in pH=6.2. The application of EDTA as a chelating agent to soil was the most efficient to enhance the phytoavailability of Pb, Hg and Cd. The concentrations of Pb, Hg, and Cd in the shoots of A. retroflexus treated with EDTA were 57 mg/kg, 14.1 mg/kg, and 30 mg/kg, respectively. Results indicated that among the three plants, A. retroflexus had great potential in phytoremediation of contaminated soils.
Synthesis of TiO2 and TiO2‐Pt and Their Application in Photocatalytic Degradation of Humic Acid
Authors: Chen Wenzhao , Ran Xianqiang , Jiang Xu , Min Hongyang , Li Dandan , Zou Liyin , Fan Jianwei , Li Guangming 
Published: January 2014

ABSTRACT: The deposit of noble metal on titanium dioxide (TiO2) has been considered as an effective strategy to improve the activity of TiO2. In this study, TiO2 nanoparticles were prepared using a sol‐gel route followed by heat treatment at elevated temperatures (573 K, 773 K, and 973 K). TiO2‐Pt catalyst (1 wt%) was prepared by depositing Pt on the surface of the prepared TiO2 nanoparticles. TiO2 and TiO2‐Pt were used as heterogeneous catalysts to remove humic acid with UV‐light (120 W) illumination. TiO2 prepared at low temperature with smaller particle size and larger specific surface area had stronger activity on humic acid degradation. Deposit of Pt would favor separation of photogenerated charges and enhance the photocatalyst activity, but its coating of the active site also inhibited degradation of humic acid. The addition of H2O2 enhanced degradation of humic acid for more active oxygen produced. Low pH (pH = 4) was helpful to adsorb humic acid on the surface of TiO2 and, correspondingly, enhance degradation of humic acid (44.4%).
Removal of Refractory Pollutants from Landfill Leachate Using Two‐Phase System
Authors: Koc‐Jurczyk Justyna 
Published: January 2014

ABSTRACT: The study focused on the problem of removing refractory substances from leachate treated by means of activated sludge method and advanced oxidation process. Biological treatment was conducted in sequencing batch biofilm reactor. Biologically treated leachate was subject to further chemical treatment with the use of Fenton reagent. The permanent dosage of H2O2 amounting to 2 mg·L−1 was applied. Fe(II):H2O2 ratio was 1:10, 1:5 and 1:3. Biological treatment allowed for removing 97% of benzene and only 20% of ethylbenzene. There was a 25% decrease in the concentration of volatile organochlorine compounds. The concentration of benzene in chemically treated leachate increased in comparison with the value found in biologically treated leachate and the growth coincided with the decreasing Fe(II):H2O2 ratio. An analysis of polycyclic aromatic hydrocarbons showed that leachate subjected to advanced oxidation contained the sum of polycyclic aromatic hydrocarbons that was lower than in biologically treated leachate, irrespective of Fe(II):H2O2 ratio.
Removal of Effluent Dissolved Organic Matter of Different Molecular Sizes by Advanced Treatments and Soil Infiltration
Authors: Zhang Xue , Zhao Xuan , Gao Yutuan , Zhang Meng 
Published: January 2014

ABSTRACT: Removal of municipal effluent‐derived dissolved organic matter (DOM) of various apparent molecular weights (AMWs) was compared among ozonation, nanofiltration, ultrafiltration, and magnetic ion exchange (MIEX) resin coagulation. These advanced technologies were applied as pretreatments for soil aquifer treatment (SAT). Soil aquifer treatment alone removed 20 to 30% of dissolved organic carbon (DOC) and UV254. Soil aquifer treatment effectively removed 100% and 76% of DOM with AMWs of 21.3 to 31.6 kDa and 0.4 to 1.0 kDa, respectively. With pretreatments of ozonation, MIEX resin coagulation and nanofiltration, substantially higher removals (40 to 75%) were achieved for DOC and UV254. The removal efficiency of the entire system decreased as nanofiltration‐SAT > ozonation‐SAT > MIEX‐SAT > ultrafiltration‐SAT, which is positively related to the removal efficiency for medium AMW (1.8 to 7.7 kDa, mainly humic substances) DOM during pretreatments. Different pretreatments should, therefore, be chosen in accordance with the water quality of feed water and water products and SAT removal efficiency.
On the Optimality of Conservation Results for Local Reflection in Arithmetic
Authors: Cordón-Franco A. , Fernández-Margarit A. , Lara-Martín F. F. 
Published: January 2014

AbstractLetTbe a recursively enumerable theory extending Elementary Arithmetic EA. L. D. Beklemishev proved that the Σ2local reflection principle forT,(T), is conservative over the Σ1local reflection principle,(T), with respect to boolean combinations of Σ1-sentences; and asked whether this result is best possible. In this work we answer Beklemishev's question by showing that Π2-sentences are not conserved forT= EA + “f is total,” wherefis any nondecreasing computable function with elementary graph. We also discuss how this result generalizes ton> 0 and obtain as an application that forn> 0,is conservative overIΣnwith respect to Πn+2-sentences.
Decidability of Definability
Authors: Bodirsky Manuel , Pinsker Michael , Tsankov Todor 
Published: January 2014

AbstractFor a fixed countably infinite structure Γ with finite relational signature τ, we study the following computational problem: input are quantifier-free τ-formulas ϕ0, ϕ1, …, ϕn that define relations R0, R1, …, Rn over Γ. The question is whether the relation R0 is primitive positive definable from R1, …, Rn, i.e., definable by a first-order formula that uses only relation symbols for R1, …, Rn, equality, conjunctions, and existential quantification (disjunction, negation, and universal quantification are forbidden).We show decidability of this problem for all structures Γ that have a first-order definition in an ordered homogeneous structure Δ with a finite relational signature whose age is a Ramsey class and determined by finitely many forbidden substructures. Examples of structures Γ with this property are the order of the rationals, the random graph, the homogeneous universal poset, the random tournament, all homogeneous universal C-relations, and many more. We also obtain decidability of the problem when we replace primitive positive definability by existential positive, or existential definability. Our proof makes use of universal algebraic and model theoretic concepts, Ramsey theory, and a recent characterization of Ramsey classes in topological dynamics.
Computably Isometric Spaces
Authors: Melnikov Alexander G. 
Published: January 2014

AbstractWe say that an uncountable metric space is computably categorical if every two computable structures on this space are equivalent up to a computable isometry. We show that Cantor space, the Urysohn space, and every separable Hilbert space are computably categorical, but the space [0, 1] of continuous functions on the unit interval with the supremum metric is not. We also characterize computably categorical subspaces of ℝn, and give a sufficient condition for a space to be computably categorical. Our interest is motivated by classical and recent results in computable (countable) model theory and computable analysis.
Homology Groups of Types in Model Theory and the Computation of H2(p)
Authors: Goodrick John , Kim Byunghan , Kolesnikov Alexei 
Published: January 2014

AbstractWe present definitions of homology groups Hn (p), n ≥ 0, associated to a complete type p. We show that if the generalized amalgamation properties hold, then the homology groups are trivial. We compute the group H2(p) for strong types in stable theories and show that any profinite abelian group can occur as the group H2 (p).
The Determinacy of Context-Free Games
Authors: Finkel Olivier 
Published: January 2014

AbstractWe prove that the determinacy of Gale-Stewart games whose winning sets are accepted by realtime 1-counter Büchi automata is equivalent to the determinacy of (effective) analytic Gale-Stewart games which is known to be a large cardinal assumption. We show also that the determinacy of Wadge games between two players in charge ofω-languages accepted by 1-counter Büchi automata is equivalent to the (effective) analytic Wadge determinacy. Using some results of set theory we prove that one can effectively construct a 1-counter Büchi automatonand a Büchi automatonsuch that: (1) There exists a model of ZFC in which Player 2 has a winning strategy in the Wadge gameW(L(),L()); (2) There exists a model of ZFC in which the Wadge gameW(L(),L()) is not determined. Moreover these are the only two possibilities, i.e. there are no models of ZFC in which Player 1 has a winning strategy in the Wadge gameW(L(),L()).
Friedberg Numbering in Fragments of Peano Arithmetic andα-Recursion Theory
Authors: Li Wei 
Published: January 2014

AbstractIn this paper, we investigate the existence of a Friedberg numbering in fragments of Peano Arithmetic and initial segments of Gödel's constructible hierarchyLα, whereαis Σ1admissible. We prove that(1) OverP−+BΣ2, the existence of a Friedberg numbering is equivalent toIΣ2, and(2) ForLα, there is a Friedberg numbering if and only if the tame Σ2projectum ofαequals the Σ2cofinality ofα.
Mad Families Constructed from Perfect Almost Disjoint Families
Authors: Brendle Jörg , Khomskii Yurii 
Published: January 2014

AbstractWe prove the consistency of together with the existence of a -definable mad family, answering a question posed by Friedman and Zdomskyy in [7, Question 16]. For the proof we construct a mad family in L which is an ℵ1-union of perfect a.d. sets, such that this union remains mad in the iterated Hechler extension. The construction also leads us to isolate a new cardinal invariant, the Borel almost-disjointness number, defined as the least number of Borel a.d. sets whose union is a mad family. Our proof yields the consistency of (and hence, ).
Anomalous Vacillatory Learning
Authors: Beros Achilles A. 
Published: January 2014

AbstractIn 1986, Osherson, Stob and Weinstein asked whether two variants of anomalous vacillatory learning, TxtFex** and TxtFext**, could be distinguished [3]. In both, a machine is permitted to vacillate between a finite number of hypotheses and to make a finite number of errors. TxtFext**-learning requires that hypotheses output infinitely often must describe the same finite variant of the correct set, while TxtFex**-learning permits the learner to vacillate between finitely many different finite variants of the correct set. In this paper we show that TxtFex** ≠ TxtFext**, thereby answering the question posed by Osherson, et al. We prove this in a strong way by exhibiting a family in TxtFex*2 TxtFext**.
Spectra of Atomic Theories
Authors: Andrews Uri , Knight Julia F. 
Published: January 2014

AbstractFor a countable structure , the spectrum is the set of Turing degrees of isomorphic copies of . For a complete elementary first order theory T, the spectrum is the set of Turing degrees of models of T. We answer a question from [1] by showing that there is an atomic theory T whose spectrum does not match the spectrum of any structure.
Copyable Structures
Authors: Montalbán Antonio 
Published: January 2014

AbstractWe introduce the notions of copyable and diagonalizable classes of structures. We then show how these notions are connected to two other notions that had already been studied for some particular classes of structures, namely the listability property and the low property.The main result of this paper is the characterizations of the classes of structures with the low property, that is, the classes whose low members all have computable copies. We characterize these classes as the ones whose structural jumps are listable.
From Bi-Immunity to Absolute Undecidability
Authors: Bienvenu Laurent , Day Adam R. , Hölzl Rupert 
Published: January 2014

AbstractAn infinite binary sequence A is absolutely undecidable if it is impossible to compute A on a set of positions of positive upper density. Absolute undecidability is a weakening of bi-immunity. Downey, Jockusch and Schupp [2] asked whether, unlike the case for bi-immunity, there is an absolutely undecidable set in every non-zero Turing degree. We provide a positive answer to this question by applying techniques from coding theory. We show how to use Walsh–Hadamard codes to build a truth-table functional which maps any sequence A to a sequence B, such that given any restriction of B to a set of positive upper density, one can recover A. This implies that if A is non-computable, then B is absolutely undecidable. Using a forcing construction, we show that this result cannot be strengthened in any significant fashion.
A Perfect Set of Reals with Finite Self-Information
Authors: Herbert Ian 
Published: January 2014

AbstractWe examine a definition of the mutual information of two reals proposed by Levin in [5]. The mutual information iswhereK(·) is the prefix-free Kolmogorov complexity. A realAis said to have finite self-information ifI (A : A)is finite. We give a construction for a perfect Π10class of reals with this property, which settles some open questions posed by Hirschfeldt and Weber. The construction produces a perfect set of reals withK(σ)≤+KA(σ)+f (σ)for any given Δ20fwith a particularly nice approximation and for a specific choice of f it can also be used to produce a perfect Π10set of reals that are low for effective Hausdorff dimension and effective packing dimension. The construction can be further adapted to produce a single perfect set of reals that satisfyK(σ)≤+KA(σ)+f (σ)for allfin a ‘nice’ class of Δ20functions which includes all Δ20orders.
On the Structure of Finite Level and ω-Decomposable Borel Functions
Authors: Ros Luca Motto 
Published: January 2014

AbstractWe give a full description of the structure under inclusion of all finite level Borel classes of functions, and provide an elementary proof of the well-known fact that not every Borel function can be written as a countable union of Σα0-measurable functions (for every fixed 1 ≤ α < ω1). Moreover, we present some results concerning those Borel functions which are ω-decomposable into continuous functions (also called countably continuous functions in the literature): such results should be viewed as a contribution towards the goal of generalizing a remarkable theorem of Jayne and Rogers to all finite levels, and in fact they allow us to prove some restricted forms of such generalizations. We also analyze finite level Borel functions in terms of composition of simpler functions, and we finally present an application to Banach space theory.
Anti-Complex Sets and Reducibilities with Tiny Use
Authors: Franklin Johanna N. Y. , Greenberg Noam , Stephan Frank , Wu Guohua 
Published: January 2014

AbstractIn contrast with the notion of complexity, a setAis called anti-complex if the Kolmogorov complexity of the initial segments ofAchosen by a recursive function is always bounded by the identity function. We show that, as for complexity, the natural arena for examining anti-complexity is the weak-truth table degrees. In this context, we show the equivalence of anti-complexity and other lowness notions such as r.e. traceability or being weak truth-table reducible to a Schnorr trivial set. A setAis anti-complex if and only if it is reducible to another setBwithtiny use, whereby we mean that the use function for reducingAtoBcan be made to grow arbitrarily slowly, as gauged by unbounded nondecreasing recursive functions. This notion of reducibility is then studied in its own right, and we also investigate its range and the range of its uniform counterpart.
Isomorphism of Computable Structures and Vaught's Conjecture
Authors: Becker Howard 
Published: January 2014

AbstractThe following question is open: Does there exist a hyperarithmetic class of computable structures with exactly one non-hyperarithmetic isomorphism-type? Given any oracle α ∈ 2ω, we can ask the same question relativized to α. A negative answer for every α implies Vaught's Conjecture for Lω1ω.
Optimization of rapeseed oil fatty acid esterification with methanol in the presence of sulfuric acid
Authors: Brinks Janis , Malins Kristaps , Kampars Valdis , Prilucka Julija , Apseniece Lauma 
Published: January 2014

Abstract
The interest in biodiesel production from low cost feedstocks is still increasing. Such feedstocks usually contain large amounts of free fatty acids, which make the currently employed base catalysts inefficient, thereby promoting the use of acid catalysts. Due to the high activity and low cost, sulfuric acid could become the most widely used acid catalyst for biodiesel production. Research undertaken so far using sulfuric acid for esterifi cation of fatty acids has shown that the products obtained fail to meet the requirements of the standard EN 14214. This paper describes a systematic study of rapeseed oil fatty acids esterification in order to obtain a product complying with the standard EN 14214. The influence of sulfuric acid concentrations (0.1-3.0%), methanol molar ratios (1:1-20:1) and reaction time (0-360 min) was evaluated. Finally, a two-stage esterification process was developed, where in optimal conditions esterification yield of 97.8% and ester content of 99.6% were achieved.