bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a correlation to study parameters affecting nitrification in a domestic wastewater treatment plant
Authors: Coskuner Gulnur , Jassim Majeed S 
Published: December 2007

AbstractBACKGROUND: Nitrification performance of an activated sludge reactor treating weak domestic wastewater was investigated for 11 months. Ammonia nitrogen removals were investigated as a function of wastewater composition and operational conditions. Backward elimination experimental design was used to determine the influence of the most important independent variables on NH3‐N removal efficiencies. Influent ammonia and biological oxygen demand (BOD5) concentrations, hydraulic retention time (HRT), mixed liquid suspended solids (MLSS), temperature, pH and dissolved oxygen (DO) concentration were considered as independent variables. This study aimed to find the most important parameters to describe nitrification performance.RESULTS: The presence of nitrification was confirmed by ammonia and nitrate variations throughout the reactor; ammonia oxidizing bacteria (AOB) populations were determined using a fluorescence in situ hybridization (FISH) method. MLSS concentration, influent BOD5 concentration and temperature were found to be the most influential factors on nitrification performance. The empirical correlation using multiple linear regressions was statistically significant and produced an adjusted coefficient of multiple determinations (R2adj) of 92.5%.CONCLUSION: Correlation provides a good understanding of the various parameters that affect the nitrification process, and could be extended to other case studies. Using these results, operators can apply proper operational strategies to maintain nitrification in wastewater treatment plants. Copyright © 2007 Society of Chemical Industry
Treatment of coking wastewater by a UBF‐BAF combined process
Authors: Zhu Shunni , Ni Jinren 
Published: December 2007

AbstractBACKGROUND: Coking wastewater is a major pollutant, produced in large quantities in many countries worldwide. This study investigates the performance of a combined system for treating coking wastewater. The system is based on an upflow blanket filter (UBF) with a biological aerated filter (BAF). Efficiency is assessed according to organic pollutants and nitrogen removal.RESULTS: It was found that hydraulic retention time (HRT) had a greater influence on the removal efficiency of NH3‐N than chemical oxygen demand (COD). The BAF facilitated simultaneous carbonaceous removal and nitrification, depending on the reactor height. The system removed 81.5% of COD and 96.4% of NH3‐N when the total HRT was 46.7 h (15.4 h for UBF and 31.3 h for BAF). Gas chromatography/mass spectrometry analysis indicated that the main components of the coking wastewater were phenols and nitrogenous heterocyclic compounds. Certain refractory compounds decomposed in the anaerobic section, resulting in the production of intermediates. Although most organics present in the influent were absent from the final effluent, a few residual contaminants could not be fully eliminated by the system.CONCLUSION: The experimental results show that the present system is feasible for the treatment of coking wastewater. Copyright © 2007 Society of Chemical Industry
Design strategies for integrated protein purification processes: challenges, progress and outlook
Authors: Nfor Beckley K , Ahamed Tangir , van Dedem Gijs WK , van der Wielen Luuk AM , van de Sandt Emile JAX , Eppink Michel HM , Ottens Marcel 
Published: December 2007

AbstractThe key to successful and efficient protein purification is the selection of the most appropriate purification techniques and their combination in a logical way to obtain the desired purification in the minimum number of steps. However, the rationalization of protein purification process development is faced with a number of challenges. In this paper, the challenges in protein purification process development are captured. The state‐of‐the‐art in protein purification process synthesis and design is reviewed and the strengths and weaknesses of the current strategies highlighted. Finally, views on the future directions of protein purification process development are presented. Copyright © 2007 Society of Chemical Industry
Ozonation of humic acid in water
Authors: Miao Hengfeng , Tao Wenyi 
Published: December 2007

AbstractBACKGROUND: Humic acids (HAs) are heterogeneous macromolecules widely dispersed in natural waters, which display significant resistance to biodegradation. Removal of HA by ozone and its related reaction mechanisms are investigated.RESULTS: Ozonation of HA showed a significant reduction of UV254, Color436 and had the capability of mineralizing the TOC to CO2 and improving the biodegradability. Fourier trandform infrared (FT‐IR) spectra, elemental composition analysis and high performance size exclusion chromatography (HPSEC) revealed that ozonation could not only change the structure characteristics but modify the molecular size distribution of HA. Volatile compounds detected by gas chromatography‐mass spectroscopy (GC‐MS) showed that ozonation brought out 43 different organics, which were identified as mainly: aldehydes, ketones, aromatics, carboxylic acids and alcohols.CONCLUSION: Ozonation of HA could be elucidated by the followed mechanism: ozonation with its direct and indirect pathway hydroxylated the HA in water, and polyhydroxy HA was further oxidized to bond rupture leading to the change of molecular structure and size distribution of HA, trimming out a series of small molecular volatile compounds. The volatile compounds with electron denoting group could be further oxidized to acids and esters, and even totally mineralized to CO2. Copyright © 2007 Society of Chemical Industry
Role of OH− in the low temperature hydrothermal synthesis of ZnO nanorods
Authors: Song Jaejin , Baek Seonghoon , Lee Jonghyuck , Lim Sangwoo 
Published: December 2007

AbstractBACKGROUND: ZnO nanorods, which have a wide range of applications, were grown on a Si substrate by low temperature hydrothermal synthesis. An understanding of the reaction mechanism of ZnO nanorods is crucial to control their growth kinetics. Therefore, the effect of OH− concentration in a zinc sulfate solution on the growth of ZnO nanorods was investigated in order to better understand the growth mechanism of ZnO nanorods.RESULTS: The growth rate and diameter of ZnO nanorods were increased by increasing the pH of the zinc sulfate solution from 10.4 to 10.6, and the highest growth rate, 850 nm h−1, was observed when the nanorods were grown in a solution with a pH of 10.6. However, further increase in the pH of the solution decreased the growth rate, due to the simultaneous dissolution of ZnO nanorods by OH−. The amount of OH− consumed by the dissolution of ZnO and other subreactions was minimized in a solution with a pH of 10.6. The intensity of c‐axis (0001) orientation was the highest in the solution with a pH of 10.6.CONCLUSION: It is concluded that the concentration of OH− plays a critical role in the hydrothermal synthesis of ZnO nanorods, and that the suppression of OH− subreactions increases the growth rate of ZnO nanorods. From the changes in the length and diameter of ZnO nanorods with synthesis time, it is suggested that the nucleation of ZnO nanocrystals occurs in the first 30 min, from which the growth of nanorods then proceeds. Copyright © 2007 Society of Chemical Industry
Cross‐cultural development of an abridged job insecurity measure
Authors: Lee Cynthia , Bobko Philip , Ashford Susan , Chen Zhen Xiong , Ren Xiaopeng 
Published: December 2007

AbstractUsing four samples from the United States and China, we developed two theoretically based abridged job insecurity (JI) scales to address researcher concerns with the length of the original 57‐item scale. These two scales contained all the components of the scale originally developed and validated by Ashford et al., 1989. Our abridged scale has 37 items (18 items for job features, 16 items for total job, and 3 items for powerlessness). We further developed a bare‐bones scale with only 25 items (10 items for job features, 12 items for total job, and 3 items for powerlessness). Results show that the content and construct validities of both the abridged and the bare‐bones scales are highly similar to the original JI scale. Our results provide support for the use of either the abridged or the bare‐bones JI scales. Copyright © 2007 John Wiley & Sons, Ltd.
Getting to the core of core self‐evaluation: a review and recommendations
Authors: Johnson Russell E. , Rosen Christopher C. , Levy Paul E. 
Published: December 2007

AbstractThe theory of core self‐evaluation (CSE) has provided organizational scholars with a framework for describing disposition‐based effects on work attitudes and behaviors. Although the CSE construct has been useful for predicting various phenomena, there are potential weaknesses concerning how it is conceptualized and used. We review limitations regarding CSE theory, its measurement, and specific traits, and provide recommendations for addressing them. Key recommendations include strengthening the theory underlying CSE, specifying CSE as an aggregate construct with causal indicators, representing CSE as a multidimensional construct rather than a scale score, and incorporating a trait that reflects approach motivation. Theoretical and empirical evidence that relate to our recommendations are presented. Copyright © 2007 John Wiley & Sons, Ltd.
Extraction, separation, and detection methods for phenolic acids and flavonoids
Authors: Stalikas Constantine D. 
Published: December 2007

AbstractThe impetus for developing analytical methods for phenolic compounds in natural products has proved to be multifaceted. Hundreds of publications on the analysis of this category of compounds have appeared over the past two decades. Traditional and more advanced techniques have come to prominence for sample preparation, separation, detection, and identification. This review provides an updated and extensive overview of methods and their applications in natural product matrices and samples of biological origin. In addition, it critically appraises recent developments and trends, and provides selected representative bibliographic examples.
Validation of a capillary zone electrophoresis method for the comparative determination of etoricoxib in pharmaceutical formulations
Authors: Dalmora Sérgio Luiz , da Silva Sangoi Maximiliano , da Silva Lucélia Magalhães , Oliveira Macedo Rui , Barth Thiago 
Published: December 2007

AbstractA CZE method was developed and validated for the analysis of etoricoxib in pharmaceutical dosage forms, using prilocaine as an internal standard. The CZE method was carried out on a fused‐silica capillary (50 μm id, effective length 40 cm). The BGE consisted of 25 mM tris‐phosphate solution at pH 2.5. The capillary temperature was maintained at 35°C, the applied voltage was 25 kV, the injection was performed using the pressure mode at 50 mbar for 5 s, with detection at 234 nm using a photodiode array detector. The method was linear in the range of 2–150 μg/mL (r2= 0.9999). The specificity and stability‐indicating capability were proven through the degradation studies and showing also that there was no interference of the excipients of the formulation. The accuracy was 99.49% with RSD of 0.66%. The limits of quantitation and detection were 2 and 0.58 μg/mL, respectively. Moreover, method validation demonstrated acceptable results for the precision, sensitivity, and robustness. The proposed method was successfully applied for the quantitative analysis of etoricoxib pharmaceutical formulations, and the results compared to the HPLC and LC‐MS/MS methods, showing nonsignificant difference (p>0.05).
Simultaneous determination of 15 marker constituents in various Radix Astragali preparations by solid‐phase extraction and high‐performance liquid chromatography
Authors: Qi Lian‐Wen , Yu Qing‐Tao , Yi Ling , Ren Mei‐Ting , Wen Xiao‐Dong , Wang Yu‐Xia , Li Ping 
Published: December 2007

AbstractAn improved quality control method was developed to simultaneously determine 15 major constituents (eight flavonoids and seven saponins) in various Radix Astragali preparations, using SPE for pretreatment of samples, HPLC with diode‐array and evaporative light scattering detectors (DAD‐ELSD) for quantification in one run, and HPLC‐ESI‐TOF/MS for definite identification of compounds in preparations. Optimum separations were obtained with a ZORBAX C18 column, using a gradient elution with 0.3% aqueous formic acid and ACN. This established method was fully validated with respect to linearity, precision, repeatability, and accuracy, and was successfully applied to quantify the 15 compounds in 19 commercial samples, including 3 dosage forms, i. e., oral solution, injection, concentrated granule, and its processed products of Radix Astragali. The results demonstrated that many factors might result in significant differences in quality of the final preparations, including crude drugs, pretreatment processes, manufacturing procedure, storage conditions, etc. Then the developed method provided a reasonable and powerful manner to ensure the efficacy, safety, and batch‐to‐batch uniformity of Radix Astragali products by standardizing each procedure, and thus should be proposed as quality control for the clinical use and modernization of herbal preparations.
Solid‐phase microextraction for the determination of benzoylureas in orange juice using liquid chromatography combined with post‐column photochemically induced fluorimetry derivatization and fluorescence detection
Authors: Parrilla Vázquez Piedad , Mughari Ahmed R. , Martínez Galera María 
Published: December 2007

AbstractA solid‐phase microextraction (SPME) method has been developed for the determination of six benzoylureas (diflubenzuron, triflumuron, hexaflumuron, teflubenzuron, lufenuron, and flufenoxuron) in natural orange juice based on the direct immersion mode of a 60 μm polydimethylsiloxane/divinylbenzene fiber. An orange juice was obtained from blended, homogenized, and diluted ecological natural orange juice samples. An aliquot of 3 mL of a spiked sample was extracted under optimum SPME conditions. The determination of benzoylureas was carried out using HPLC combined with post‐column photochemically induced fluorimetry derivatization and fluorescence detection. The limits of quantification obtained in matrix were within the range of 0.02 to 0.04 mg/kg and these limits are lower than the maximum residue levels established in Spanish regulations for all pesticides in this study. Recoveries in juice samples ranged between 85 and 110% and relative standard deviations between 1.8 and 7.4%.
GC/MS of terpenes in walnut‐tree leaves after accelerated solvent extraction
Authors: Fojtová Jitka , Lojková Lea , Kubáň Vlastimil 
Published: December 2007

AbstractTerpenes,e. g.(+)‐α‐pinene, (–)‐camphene, (–)‐(‐pinene, myrcene,R‐(+)‐limonene, eucalyptol, (±)‐linalool, (–)‐bornyl acetate, (–)‐trans‐caryophyllene, and α‐humulene were determined in leaves of walnut trees from the Juglandaceae family (walnut tree, royal (J. regiaL.), black (J. nigraL.), and Siebold (J. sieboldiana, var. Cordiformis Lam.) using gas chromatography with mass spectrometric detection. Terpenes were repeatedly (3 cycles, 5 min each) extracted from leaves of walnut trees by accelerated (pressurized) solvent extraction (ASE) 150 bar and 120°C. The efficiency of ASE extraction was superior to that of steam distillation, solvent extraction according to Soxhlet, sonication, and extraction by agitation. Differences in relative concentrations and distribution of terpenes were studied in dependence on the species of walnut tree and on different locations.
The impact of singlet oxygen on lipid oxidation
Authors: Van Dyck Stefaan 
Published: December 2007

AbstractOxidation plays a fundamental role in the reduction of the quality of fats, oils and many other principal ingredients in food or animal feed. A significant amount of research data is available on the impact of autoxidation caused by the most abundant and stable form of oxygen: triplet oxygen (3O2). An alternative oxidation process occurs when lipids are exposed to a light source, even at low temperatures. Many molecules are able to absorb energy from light after which this energy is transferred to an oxygen molecule. This process leads to the conversion of the most abundant triplet oxygen into the more reactive singlet oxygen (1O2). Both types of oxygen react very differently with lipids and other nutrients due to the dissimilarity in their fundamental chemical structure. This allows researchers to study the different possible oxidation pathways and consequently to develop potential strategies to delay oxidation for the improvement of shelf life.
Structural Changes of Casein Micelles in a Calcium Gradient Film
Authors: Gebhardt Ronald , Burghammer Manfred , Riekel Christian , Roth Stephan Volkher , Müller‐Buschbaum Peter 
Published: December 2007

AbstractCalcium gradients are prepared by sequentially filling a micropipette with casein solutions of varying calcium concentration and spreading them on glass slides. The casein film is formed by a solution casting process, which results in a macroscopically rough surface. Microbeam grazing incidence small‐angle X‐ray scattering (µGISAXS) is used to investigate the lateral size distribution of three main components in casein films: casein micelles, casein mini‐micelles, and micellar calcium phosphate. At length scales within the beam size the film surface is flat and detection of size distribution in a macroscopic casein gradient becomes accessible. The model used to analyze the data is based on a set of three log‐normal distributed particle sizes. Increasing calcium concentration causes a decrease in casein micelle diameter while the size of casein mini‐micelles increases and micellar calcium phosphate particles remain unchanged.magnified image
Measurement of Spin Diffusion Coefficients in Glassy Polymers: Failure of a Simple Scaling Law
Authors: Meurer Bernard , Weill Gilbert 
Published: December 2007

AbstractFor a series of polymers, the spin diffusion coefficients D do not scale as predicted from a simple expression based on regularly spaced nuclei. We compare D for PVA and polystyrene with their side group either protonated or deuterated. For polystyrene, D is considerably reduced from 600–800 to 65 nm2 · s−1. For PVA, D is already small for the fully protonated chain and is only slightly reduced from 170 to 130 nm2 · s−1. This indicates that the rapidly rotating methyl group does not contribute appreciably to spin diffusion between neighboring chains and confirms that the mean proton density is not the pertinent parameter to control D.magnified image
Copolyesters Containing Terephthalic and Bio‐Based Furanic Units by Melt‐Polycondensation
Authors: Abid Majdi , Kamoun Wided , Gharbi Rachid El , Fradet Alain 
Published: December 2007

Abstract5,5′‐Isopropylidene‐bis(ethyl 2‐furoate), a monomer prepared from bio‐based ethyl 2‐furoate, was reacted with dimethyl terephthalate and ethan‐1,2‐diol (ED) by melt polycondensation in order to obtain copolyesters containing both terephthalate and furoate units. The conventional two‐step method involving (i) the formation of a hydroxyethyl‐terminated oligomer by reaction of starting diester mixture with excess ED and (ii) a polycondensation step with elimination of ED was used to obtain high molar mass copolyesters. Copolymers of various compositions were synthesized and characterized by 1H NMR, DSC, and TGA. For all compositions, the degree of randomness, determined by 1H NMR, was close to 1, reflecting a random distribution of terephthalic and furanic ester units in polymer chains. The resulting materials are amorphous polymers (Tg = 70–80 °C) with good thermal stability.magnified image
A Smart Polymer with Ion‐Induced Negative Shift of the Lower Critical Solution Temperature for Phase Transition
Authors: Mi Peng , Chu Liang‐Yin , Ju Xiao‐Jie , Niu Catherine Hui 
Published: December 2007

AbstractA novel thermo‐responsive smart copolymer that can selectively respond to specific ions, poly[(N‐isopropylacrylamide)‐co‐(benzo‐15‐crown‐5‐acrylamide)], has been synthesized and characterized. The copolymer exhibits a negative shift of the lower critical solution temperature (LCST) for phase transition that is specifically responsive to certain alkali metal ions. The order of significance of the LCST shift that is induced by ions is K+ > Cs+ > Na+ > Li+. The greater the number of crown ether units in the copolymer, or the larger the ion concentration, the higher the sensitivity and selectivity of the copolymer for cation recognition. Because of its novel ion‐responsive characteristics, the proposed smart copolymer is a promising new candidate material for sensors, actuators, switches, and so on.magnified image
Surface‐Active Gold Nanoparticles with Mixed Polymer Brushes as Surfactants in the Preparation of Polystyrene Colloid Particles
Authors: Liu Li , Zhang Jian , Wu Chenglin , Zhao Hanying 
Published: December 2007

AbstractGold nanoparticles with hydrophobic polystyrene (PS) and hydrophilic poly[poly(ethylene glycol) methyl ether methacrylate] (PPEGMA) mixed polymer brushes are prepared. Different morphologies of the nanoparticles can be observed in chloroform (a common solvent for both of the polymers) and water (a precipitant for PS and a good solvent for PPEGMA). The nanoparticles can be used as surfactants in Pickering suspension polymerization. Upon addition of nanoparticles to a mixture of oil and water, the nanoparticles locate at the interface and the size of the oil droplets gets smaller. After polymerization of styrene oil droplets PS colloid particles with gold nanoparticles on the surface can be obtained.magnified image
Modification of Polymer Substrates with Low Surface Free Energy Material by Low‐Temperature Cured Polybenzoxazine
Authors: Liao Chun‐Syong , Wu Jiann‐Shing , Wang Chih‐Feng , Chang Feng‐Chih 
Published: December 2007

AbstractThe B‐ala/AIBN PBZ system has a high extent of ring‐opening of oxazine because phenol‐containing oligomers are formed at the early stage of the curing process. As a result, the B‐ala/AIBN PBZ system possesses a relatively stronger intramolecular hydrogen bonding and lower surface energy than the pure B‐ala system at low temperature curing. In this context, poly(4‐vinyl pyridine), poly(4‐vinyl phenol) thin films and polycarbonate substrates, which lack liquid resistance, possess low surface free energy after modification with B‐ala/AIBN = 5/1 PBZ.magnified image
Acid‐Degradable Core‐Crosslinked Micelles Prepared from Thermosensitive Glycopolymers Synthesized via RAFT Polymerization
Authors: Zhang Ling , Bernard Julien , Davis Thomas P. , Barner‐Kowollik Christopher , Stenzel Martina H. 
Published: December 2007

AbstractA thermoresponsive block copolymer, namely poly(acryloyl glucosamine)‐block‐poly(N‐isopropylacryamide) (PAGA180‐b‐PNIPAAM350) was simultaneously self‐assembled and crosslinked in aqueous medium via RAFT polymerization at 60 °C to afford core‐crosslinked micelles exhibiting a glycopolymer corona and a PNIPAAM stimuli‐responsive core. An acid‐labile crosslinking agent, 3,9‐divinyl‐2,4,8,10‐tetraoxaspiro[5.5]undecane, was employed to generate thermosensitive and acid‐degradable core‐shell nanoparticles. Stable against degradation at pH = 6 and 8.2, the resulting core crosslinked micelles readily hydrolyzed into well‐defined free block copolymers at lower pH (30 min and 12 h respectively at pH = 2 and 4).magnified image