bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long‐Term Diffusive Samplers for the Indoor Air Quality Evaluation
Authors: Bertoni Giuliano , Ciuchini Carla , Tappa Remo 
Published: September 2004

AbstractThree kinds of diffusion samplers, conceived to perform long‐term samplings in indoor sites are illustrated in this work. Two of them, in part deriving from the previous “Analyst for VOC” device, extend the field of application up to the semi‐volatile organic compounds (SVOC), PAHs and nicotine in particular. A third device, which employs a basic barium hydroxide solution as an absorbing medium, is proposed for the determination of carbon dioxide levels which indicate the air change quality in the indoor sites. Laboratory and field experiments, performed in order to assess the reliability of the proposed devices, are shown. A monthly monitoring campaign, performed at three private apartments in Rome and its outskirts highlights that the indoor pollution levels are a complex function of various concurrent and opposite factors, like external air pollution, internal sources, air change rate and sink effect of surfaces, which contribute to depletion phenomena through adsorption and/or decomposition processes.
GC—MS in Space Research: Decoding Complex Isothermal Chromatograms Recovered from Space Missions
Authors: Pietrogrande Maria Chiara , Zampolli Maria Grazia , Dondi Francesco 
Published: September 2004

AbstractAn analytical procedure is described to study GC—MS isothermal chromatograms simulating those recovered from space missions: in fact GC plays a predominant role in space missions devoted to characterizing the chemical composition of extraterrestrial atmospheres. SIM (selected ion monitoring) detection was used for monitoring selected chemical classes: a simplified chromatogram can be obtained giving information on the chemical composition of the complex mixture. Since only isothermal GC chromatograms are allowed by flight constraints, a time axis transformation is required to make them homogeneous: i.e., constant retention increments for CH2 additions in terms of a homologous series. The order in the linearized chromatogram can be simply singled out with a chemometric approach based on the study of the Autocovariance Function (ACVF) computed on the digitized chromatogram: the plot of the experimental autocorrelation function (EACF) shows wellshaped peaks if constant interdistances are repeated in different regions of the chromatogram. The method was applied to standard mixtures representative of planetary atmospheres — hydrocarbons, nitriles and oxygenated compounds with between 3 and 12 carbon atoms — analyzed in flight simulating conditions. The coupling of the selectivity of SIM detection with the interpretation power of the EACF procedure proves to be a powerful tool for interpreting data recovered from space missions: the chemical composition of the mixture can be identified by handling the raw SIM chromatograms.
Characterization of Polycyclic Aromatic Hydrocarbons and Carbonyl Compounds in Diesel Exhaust Emissions
Authors: Mabilia Rosanna , Cecinato Angelo , Tomasi Scianò Maria Concetta , di Palo Vincenzo , Possanzini Massimiliano 
Published: September 2004

AbstractExhaust emissions from a recent model heavyduty diesel vehicle (city bus) in a chassis dynamometer were measured during a transient driving cycle. Particlebound polycyclic aromatic hydrocarbons (PAHs) and gaseous carbonyls, substances that create health hazards and are, as yet, unregulated were collected, the former on filters and the latter on dinitrophenylhydrazine (DNPH)�coated silica cartridges and analysed by GC—MS and HP—LC, respectively. PAH emission rates decreased with the number of benzene fused rings. They averaged 0.2 mg km—1 for a total of 11 PAHs ranging from fluoranthene to benzo(ghi)perylene. Fluoranthene and pyrene accounted for 90% of total PAHs. The sum of emission rates of C1∼C6 carbonyls averaged 174 mg km—1, even if formaldehyde alone represented ∼ 70% of the total carbonyl mass, followed by acetaldehyde (13%). Results obtained were compared with emission data reported in previous studies.
Silicon Inverse Opal—A Platform for Photonic Bandgap Research
Authors: Tétreault N. , Míguez H. , Ozin G. A. 
Published: September 2004

AbstractThis article focuses attention on recent research on the silicon inverse opal, the first self‐assembled or bottom–up synthetic photonic crystal to exhibit a complete photonic bandgap (PBG) at 1.5 μm[1] in accordance with theoretical predictions.[2] The silicon inverse opal has since proven to be a useful platform for assembling on‐chip films[3] and in‐chip patterns,[4] engineering extrinsic defects,[5] mapping photon density of states,[6] switching light with light, and inhibiting spontaneous emission.[7] Also, new and exciting colloidal‐crystal‐based structures are being developed based on experimental and theoretical knowledge acquired for the synthesis of inverted silicon photonic crystals.[8–10] It has also inspired the idea of the silicon inverse opal heterostructure, a theoretical construct that could enable an all‐optical microchip for single mode diffractionless waveguiding of light in air throughout a bandwidth of more than 70 nm at 1.5 μm.[11]
Equilibrium theory analysis of dual reflux PSA for separation of a binary mixture
Authors: Ebner Armin D. , Ritter James A. 
Published: September 2004

AbstractA dual reflux (DR) PSA cycle that combines the features of a conventional (stripping reflux) PSA cycle with those of a new enriching reflux PSA cycle is analyzed to show its potential for separating gas mixtures. On the basis of isothermal equilibrium theory applied to linear isotherms, the ultimate separation is carried out where the binary feed is separated into two pure components with 100% recovery of each component. This very idealized analysis reveals that such a separation is possible over a wide range of conditions, even with pressure ratios as low as 1.1. This analysis also reveals that low throughputs and high heavy component recycle ratios are inherently associated with DR PSA cycles, both of which may be detrimental to the process economics. High throughputs and low heavy product recycle ratios are indeed achievable, but only when using low pressure ratios and less selective adsorbents, both counterintuitive results that make sense when considering the perfect separation is always being achieved. Although these trends may not carry over to actual practice, because the model developed here is overly simplified and invalid under certain conditions, this analysis shows that it may indeed be entirely feasible to separate a binary gas mixture into two relatively pure components with very high recoveries using a DR PSA cycle operating with a very low pressure ratio and, hence, expenditure of energy. © 2004 American Institute of Chemical Engineers AIChE J, 50: 2418–2429, 2004
Macroinstability uncovered in a Rushton turbine stirred tank by means of LES
Authors: Hartmann H. , Derksen J. J. , van den Akker H. E. A. 
Published: September 2004

AbstractLow‐frequency mean flow variations, identified experimentally in various stirred‐tank geometries, are studied by means of large eddy simulations in a Rushton turbine stirred tank. The focus is on flow structures, and the spectral characteristics of the velocity components. The lattice‐Boltzmann Navier‐Stokes solver, and the Smagorinsky subgrid‐scale model, are adopted for solving the stirred tank flow, and boundary conditions are imposed by means of an adaptive force‐field technique. Simulations performed at Reynolds numbers 20,000 and 30,000 on grid sizes of 1203, 1803, and 2403 grid nodes confirm the experimentally found flow variations at various monitoring points in the bulk flow. The period of the flow variations found in the bulk of the tank corresponds to approximately 250 blade passage periods. A simulation performed at a Reynolds number of 12,500 showed pronounced flow variations with a timescale of about 65 blade passage periods, which is consistent with experimental observations. Transient flow field results in the bulk flow of the tank uncover a whirlpool type of precessing vortex, of which the impact on the kinetic energy of the velocity fluctuations is further analyzed. © 2004 American Institute of Chemical Engineers AIChE J, 50: 2383–2393, 2004
Role of polyelectrolyte charge density in tuning colloidal forces
Authors: Abraham T. , Christendat D. , Xu Z. , Masliyah J. , Gohy J. F. , Jérôme R. 
Published: September 2004

AbstractAn atomic force microscope was used to study the effects of polymer charge density on surface interactions between similarly charged silica surfaces. Copolymers of acrylamide and acrylic acid of three different charge densities (fp = 15, 40, and 70%) were used. The dynamic light‐scattering technique was used to obtain the characteristic size of these polymers in solution. Flocculation tests were performed to complement force–distance measurement. At 20 mM KCl and pH ∼ 8.0, the low charge density copolymer (fp = 15%) caused a purely repulsive force profile between silica surfaces irrespective of the added polymer concentration, suggesting a strong adsorption of the copolymer on the surface. The medium (fp = 40%) and high (fp = 70%) charge density copolymers, on the other hand, provided an adhesive bridging attraction at low polymer concentrations, but a purely repulsive force at higher polymer concentrations. The range of these repulsive forces, however, was significantly smaller than that measured for the low charge density polymer. The medium and high charge densities exhibit nearly an identical behavior in controlling the intersurface forces, although the forces are different with respect to magnitude. The flocculation tests follow the same trend as that of force–distance data, where a complete, a partial, and no flocculation observed with high, medium, and low charge density polymers, respectively. In all the cases, the range of surface interactions can be correlated with the polymer chain dimension corresponding to the fast diffusion process (individual chains) obtained from dynamic light‐scattering measurements. Mean‐field models proposed for charged polymers can qualitatively explain both the dependency of bridging interactions on polymer charge density and the dependency of force–distance profiles on added polymer concentrations. Finally, a mean‐field model was used quantitatively to account for the measured electrosteric interactions and their dependency on polymer charge density. © 2004 American Institute of Chemical Engineers AIChE J, 50: 2613–2626, 2004
Adolescent impulsivity predicts adult dominance attainment in male vervet monkeys
Authors: Fairbanks Lynn A. , Jorgensen Matthew J. , Huff Adriana , Blau Karin , Hung Yung‐Yu , Mann J. John 
Published: September 2004

AbstractAdolescence is characterized by behavioral and physiological changes that prepare individuals for the transition to adulthood. The purpose of this study was to evaluate the effects of behavioral, morphological, neurobiological, and developmental characteristics of adolescent male vervets in predicting later dominance attainment. Thirty‐six adolescent male vervets were tested for social impulsivity by means of the Intruder Challenge test while they were still living in their natal groups. Body weight and cerebrospinal fluid (CSF) metabolites of serotonin, dopamine, and norepinephrine were measured before they were introduced into new matrilineal breeding groups at age 5. Stable adult dominance rank was determined at age 6, 1 year following introduction. The results indicated that body weight, adolescent impulsivity, and levels of 5‐hydroxyindoleacetic acid (5‐HIAA) and homovanillic acid (HVA) in CSF predicted adult dominance attainment. As expected, males that were above average in body weight prior to introduction were significantly more likely to become dominant. Males that were high in impulsivity as adolescents, and low in 5‐HIAA prior to introduction were more likely to achieve stable alpha male status 1 year following introduction. The combination of these three factors resulted in correct prediction of rank attainment for 92% (33/36) of the males. Two other factors–maternal dominance rank and a measure of social anxiety from the Intruder Challenge test–were not related to adult dominance attainment in this sample. These results support the idea that there are benefits of a high‐risk, high‐gain strategy is beneficial for adolescent and young adult male vervets. They also demonstrate that adolescent impulsivity is age‐limited. Males that achieved high rank moderated their behavior as adults, and no longer scored high in impulsivity relative to their age peers. Am. J. Primatol. 64:1;–17, 2004. © 2004 Wiley‐Liss, Inc.
Reproductive output, maternal age, and survivorship in captive common marmoset females (Callithrix jacchus)
Authors: Smucny Darlene A. , Abbott David H. , Mansfield Keith G. , Schultz‐Darken Nancy J. , Yamamoto M. Emilia , Alencar Anuska Irene , Tardif Suzette D. 
Published: September 2004

AbstractCommon marmosets (Callithrix jacchus) demonstrate significant variation in reproductive output on both a yearly and lifetime basis in comparison to other anthropoid primates. We explore the factors that may be most important in determining reproductive variation in captive common marmosets. Studies have found that maternal age, maternal condition, and dam survivorship are related to reproductive output; however, these reports are not in agreement and are far from conclusive. With the use of a large, multicolony, demographic database pooling data across five marmoset colonies, we examined litter information for 1,649 litters, and reproductive summaries for 400 dams to assess 1) how reproductive output variation (total production, total weaned production) is determined by litter size, interbirth interval (IBI), age at first birth, and dam survival age; 2) the relationship between maternal age and reproductive output variables; and 3) relationship between the reproductive output variables and survival. We used stepwise regression procedures to describe the amount of variation in lifetime reproductive output among dams, and found that mean litter size accounted for 18% of the variance in total production, survival age accounted for 10.6%, age at first birth accounted for 8.8%, and mean IBI accounted for 5%. For total (nonzero) weaned production, survival age accounted for 7.6% of variance, age at first birth accounted for 7.2%, mean IBI accounted for 2%, and mean litter size accounted for 1.6%. We identified significant effects (P<0.05) of maternal age on litter size and IBI length, but no effect of dam age on weaned litter size. Cox proportional hazards regression analyses revealed significant effects (P<0.01) of number of litters, age at first birth, and site on dam survivorship. Dams that produced more litters showed higher survivorship. Age at first birth showed a positive relationship with dam survivorship, i.e., dams that delayed first reproduction had higher survival. Our findings about reproductive variation in marmosets may have practical applications for the management of marmoset breeding colonies. Am. J. Primatol. 64:107–121, 2004 © 2004 Wiley‐Liss, Inc.
Investigation of shear effects on styrene free radical polymerization using a narrow channel reactor
Authors: Leveson P. , Dunk W. A. E. , Jachuck R. J. 
Published: September 2004

AbstractSpinning disc reactor technology has been demonstrated to achieve significant enhancements in the rates of free radical polymerization. It is believed that these enhancements are related to the centrifugal and shear conditions that exist on the disk and it is the objective of this study to elucidate the role of shear in thin films in a plug flow regime. Polymerizing systems have been subjected to shear fields in the range of 0.4 to 2,173 s−1 and comparisons between conversion profiles and polymer product properties have been made. It has been found that shear fields have little or no effect on these systems while the reaction is in the kinetically controlled regime and it is concluded that the observed rate enhancements of free radical polymerization on a spinning disk are not largely attributable to the high rates of shear experienced by the thin film as it traverses the disk. Our studies therefore continue to assess the role of flow divergence and centrifugal extension in the kinetics of polymerization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94:1365–1369, 2004
Characterization of the formation and degradation of a polyacrylamide microgel
Authors: Chen Fangeng , Wang Hongjuan , Zhu Chuanfeng , Ren Lingling , Li Jing 
Published: September 2004

AbstractThe morphology of polyacrylamide microgel in gelation and degelation procedures is characterized by atomic force microscopy. The polymer concentration, the cross‐linker concentration, and the type of cross‐linker have significant influence on the microstructure of polyacrylamide. The changes in aggregation status result in changes in the rheological properties of the polymer solution and microgel. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94:1375–1380, 2004
New polymer syntheses XXVIII. Synthesis and thermal behavior of new organometallic polyketones and copolyketones based on diferrocenylidenecyclohexanone
Authors: Aly Kamal I. 
Published: September 2004

AbstractA new interesting category of organometallic polyketones and copolyketones were synthesized via the Friedel–Crafts reaction through the polymerization of 2,6‐[bis (2‐ferrocenyl)methylene] cyclohexanone (II) with different diacid chlorides. The model compound was synthesized by reacting the monomer (II) with benzoyl chloride and characterized by 1H‐NMR, IR, and elemental analyses. The polyketones and copolyketones were insoluble in most organic solvents but easily soluble in protic solvents. The thermal properties of these polyketones and copolyketones were evaluated and correlated to their structural units by thermogravimetric analysis and DSC measurements, and they had inherent viscosity of 0.29–0.52 dI g−1. Moreover, the electrical conductivity of one of the polyketones, as a selected example, namely poly [carbonyl‐terephthaloyloxy‐ (2‐oxo‐1,3‐cyclohexanediylidene)methylidyne‐ferrocenyl], Va, and copolyketone, VI, was investigated above the temperature range (300–500 K) and it followed an Arrhenius equation with activation energy 2.09 eV. The morphological properties of selected example of polyketones were determined by scanning electron microscopy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1440–1448, 2004
Synthesis and characterization of poly(glycidyl methacrylate)/Na‐montmorillonite nanocomposites
Authors: Çelik Meltem , Önal Müşerref 
Published: September 2004

AbstractPoly(glycidyl methacrylate)/Na–montmorillonite nanocomposites were synthesized by free‐radical polymerization of glycidyl methacrylate containing dispersed montmorillonite. By changing the concentration of glycidyl methacrylate several polymer–clay nanocomposites were prepared and the resulting nanocomposites were characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The results indicated that the properties of the composite were significantly improved. The thermogravimetric analysis results revealed that the degradation temperatures of nanocomposites were higher than that of pure polymer and the thermal degradation rates decreased. Examination of these materials by scanning electron microscopy showed that the clay layers are dispersed homogenously in the polymer matrix and the formation of intercalation nanostructure. Furthermore, adsorptive, moisture regain, and water uptake properties of nanocomposites were also investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1532–1538, 2004
Methods to determine solubility parameters of polymers at high temperature using inverse gas chromatography
Authors: Huang Jan‐Chan 
Published: September 2004

AbstractExperimental values of Flory–Huggins parameters, χ, between polymers and probes, are frequently used to determine the solubility parameters of the polymers by the method of DiPaola–Baranyi and Guillet. The solubility parameters of probes were usually estimated by using heat of vaporization. When χ is measured at a temperature near the critical temperature of the probes and used to determine the solubility parameter of polymers, the departure of enthalpy of the probe vapor from the ideal gas state should be considered. This study discussed the method to make the correction and its effect on the determination solubility parameter of polymers. Without correction in the vapor phase enthalpy, the solubility parameters of the probes and polymer tend to be underestimated and the error increases when the critical temperature is approaching. Analytical expressions for the effect of correction on the solubility parameter of probes and parameters of polymers were derived. By use of probes with a range of solubility parameters on both sides of the solubility parameter of polymers, the correlation between parameters of polymers was shown to be reduced. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1547–1555, 2004
U1 RNA induces innate immunity signaling
Authors: Hoffman Robert W. , Gazitt Tal , Foecking Mark F. , Ortmann Robert A. , Misfeldt Michael , Jorgenson Rebecca , Young Steven L. , Greidinger Eric L. 
Published: September 2004

AbstractObjectiveThe U1–70‐kd RNP is a prominent target of autoimmunity in connective tissue diseases. In this study, we explored whether its endogenous ligand, U1 RNA, mediates a proimmune signal and may be immunogenic.MethodsWe assayed the proliferation of control and MyD88‐knockout splenocytes in response to in vitro–synthesized U1 RNA, and measured interleukin‐6 (IL‐6) and IL‐8 secretion induced by U1 RNA in a human cell line competent for signaling through Toll‐like receptor 3 (TLR‐3) and TLR‐5.ResultsTreatment with U1 RNA or with poly(I‐C), a known agonist of TLR‐3, induced approximately twice as much control splenocyte proliferation as did treatment with RNase‐digested U1 RNA. Proliferation in response to either poly(I‐C) or U1 RNA by MyD88‐knockout splenocytes was similarly attenuated. Similar to poly(I‐C), U1 RNA induced significant secretion of both IL‐6 and IL‐8 from a TLR‐3–expressing human cell line; in contrast, the TLR‐5 agonist flagellin induced predominantly IL‐8 secretion. Pretreatment of U1 RNA with RNase abolished IL‐6 and IL‐8 secretion.ConclusionU1 RNA is capable of inducing manifestations consistent with TLR‐3 activation. The ability of U1 RNA (which has a substantial double‐stranded secondary structure) to activate TLR‐3 may contribute to the immunogenicity of the U1–70‐kd autoantigen. Stimulation of innate immunity by native RNA molecules with a double‐stranded secondary structure may help explain the high prevalence of autoimmunity to RNA binding proteins.