bluuebunny/crossref_metadata_2025 huggingface dataset:
Field Performance of Warm-Mix Asphalt at National Center for Asphalt Technology Test Track
Authors: Prowell Brian D. , Hurley Graham C. , Crews Everett
Published: December 2007

Warm-mix asphalt (WMA) mixes produced by an emulsion process were evaluated under accelerated loading in three total sections of the National Center for Asphalt Technology Test Track and used as the surface mix for two of the sections. Evotherm was incorporated into the same mixes used previously on the track. In-place densities of the WMA surface layers were equal to or better than the hot-mix asphalt (HMA) surface layers, even when compaction temperatures were reduced by 8°C to 42°C (15°F to 75°F). Laboratory rutting-susceptibility tests conducted in the asphalt pavement analyzer indicated similar performance for the WMA and HMA surface mixes with the PG 67-22 base asphalt. However, laboratory tests indicated an increased potential for moisture damage with the WMA mixes. The two WMA sections and the HMA section showed excellent rutting performance in the field after the application of 515,333 equivalent single-axle loads in a 43-day period. One of the WMA sections was also evaluated for quick turnover to traffic and showed good performance.
Investigation of Properties of Plant-Produced Reclaimed Asphalt Pavement Mixtures
Authors: Shah Ayesha , McDaniel Rebecca S. , Huber Gerald A. , Gallivan Victor L.
Published: December 2007

The influence of reclaimed asphalt pavement (RAP) content on the mixture and recovered binder properties of plant-produced hot-mix asphalt (HMA) was examined by studying the complex moduli of RAP mixtures and binders. RAP was added at 15%, 25%, and 40% levels to HMA with PG 64-22 and at 25% and 40% levels to HMA with PG 58-28 binder. In addition, control mixture samples with PG 64-22 and no RAP were also collected and tested for comparison. Compacted specimens were tested to determine the complex dynamic moduli (|E*|) at three temperatures. Complex shear moduli (|G*|) of the binders recovered from these HMA samples, RAP samples, and original binders were determined at the same test temperatures. Low-temperature creep compliance and indirect tensile strength of the mixtures were also determined, and these results were used to estimate the critical cracking temperature of the pavement. Statistical analysis indicated that there were no differences in mean strength and |E*| of the mixtures at the 15% and 25% RAP levels. Some differences between the control mixture and the 40% RAP mixtures were found only at the higher test temperatures.
Evaluation of N-Curve Methodology for Analysis of Complex Bottlenecks
Authors: Kurada Lakshmi , Öğüt K. Selçuk , Banks James H.
Published: December 2007

A complex bottleneck is a section that has several bottlenecks with varying patterns of activation in close proximity to one another; issues of concern are the number and location of individual bottlenecks and the events associated with their activation. The usefulness of N-curve methodology for analyzing complex freeway bottlenecks was evaluated by applying it in the reanalysis of a section of southbound I-5 near San Diego, California, that had been used in a previous study. The reanalysis was based on ordinary loop detector data and considered the relationship between changes in vehicular storage in individual sections (determined by N-curve analysis) and the time series of speeds. Information provided by the N-curve analysis contributed to improved understanding of the section by establishing the existence of multiple bottlenecks in two of the sections, but its contribution was modest when compared with what had already been learned from a careful analysis of speeds. A major difficulty in applying the N-curve technique was the uncertainty of the correction of accumulated errors resulting from count biases. A simple uniform correction proved inadequate in several cases because the biases appeared to be time-dependent; other approaches to bias correction led to plausible results in some of these cases but not others, and in all cases the uncertainty of the bias corrections leads to considerable uncertainty in the queue-size estimates.
Approximated Headway Distributions of Free-Flowing Traffic on Ohio Freeways for Work Zone Traffic Simulations
Authors: Zwahlen Helmut T. , Oner Erdinc , Suravaram Kiran R
Published: December 2007

Headway or interarrival time (IAT) data of successive vehicles in free-flowing traffic ahead of work zones for each lane on six different Ohio freeways (two with two lanes in one direction, three with three lanes, and one with four lanes) for 3 days were measured and analyzed. Approximated IAT distributions were generated as a function of the traffic volume for each lane, and relationships between traffic volumes and approximate cumulative IAT distributions were established; this allowed a direct conversion from hourly traffic counts to corresponding cumulative IAT distributions. On the basis of the validation of these IAT distributions with IAT data collected in an independent study, this conversion method produces fairly accurate cumulative IAT distributions for selected hourly traffic volumes. A set of cumulative IAT distribution spreadsheets may be downloaded at webce.ent.ohiou.edu/orite/cumulativeIATdistributions.html. It was also found that the same approximated cumulative IAT distribution can be used to model and simulate free-flowing traffic at other freeway locations in Ohio. It is not known whether these universal approximated IAT distributions would apply for freeways in other states.
Modeling Interdependence in Household Residence and Workplace Choices
Authors: Waddell Paul , Bhat Chandra , Eluru Naveen , Wang Liming , Pendyala Ram M.
Published: December 2007

Models of residential and workplace location choice prevalent in the literature often assume that one choice dimension is exogenous to the other. But a broad and uniform assumption that one choice dimension is exogenous and influences the other may be too strong to use as the foundation for current behavioral research or applied policy analysis. This paper examines the interdependence of residence and workplace choices and develops a novel approach to modeling these choice dependencies. Two problems related to such joint modeling efforts are addressed. First, through a latent market segment modeling approach, the paper offers a methodology for accommodating different sequential decision-making processes that may be present in the population–for example, residential location may be chosen first and may influence workplace location for one segment and vice versa. Second, the modeling approach offers a means of overcoming the exploding choice set problem when attempting to model multidimensional choice phenomena. The overall aim of the work is to model the structure of the interdependency between the choices that a household makes about residence location and the workplace choices of the workers in the household in the context of an integrated activity location and travel forecasting framework. This paper presents a joint model of residence location and workplace using activity-based travel survey data collected in the Puget Sound region of Washington state in 1999, with novel adaptation of recent methods for incorporating latent market segmentation within discrete choice models.
‘Cycle to cycle’ optimizing control of simulated moving beds
Authors: Grossmann Cristian , Amanullah Mohammad , Erdem Gültekin , Mazzotti Marco , Morbidelli Massimo , Morari Manfred
Published: December 2007

The novel feature of the presented simulated moving bed (SMB) controller is its capability to make use of the average outlet concentration of the product streams over a cycle as feedback information, i.e., ‘cycle to cycle’ control. Its effectiveness is confirmed experimentally on an eight‐column four‐section laboratory SMB unit, which is used to separate a binary mixture of the nucleosides, uridine and guanosine. The performance of the ‘cycle to cycle’ SMB control scheme is also demonstrated by several SMB simulation runs that are chosen to test the robustness of the controller. Furthermore, the case where measurements have a time delay is presented. The results illustrate that the ‘cycle to cycle’ controller is able to meet the products' purity specifications and operate the process optimally with minimal information about the system regardless of the disturbances that might take place during the operation. © 2007 American Institute of Chemical Engineers AIChE J, 2008
Micrometer‐sized monodispersed silica spheres with advanced adsorption properties
Authors: Chen Y. , Wang Y. J. , Yang L. M. , Luo G. S.
Published: December 2007

Micrometer‐sized monodispersed mesoporous silica spheres with adjustable particle diameter and adjustable pore structure were successfully prepared. Drops of a silica sol were injected by a microfluidic device into a heated oil bath where the droplets solidified during sedimentation. Drop size was varied by control of the rates of the oil flow past the silica sol injector. The silica sol was made by prehydrolysis of tetraethyl orthosilicate (TEOS) in an aqueous acidic solution using a triblock copolymer as the template. Acrylamide monomer was added in the sol after prehydrolysis to accelerate the solidification rate of drops in the oil bath. The amount of monomer was used to control the pore sizes in the silica particles. The effect of synthesis conditions on the morphology and pore structure of spheres was investigated. Silica spheres with different surface morphology and internal structure were obtained by changing the composition of sedimentation medium. Pore diameter and pore‐size distribution can be adjusted effectively by controlling the concentration of silica source, acid or polymeric monomer in the aqueous phase. The prepared silica spheres have high‐surface area (>550 m2/g), large pore volume (>1.1 cm3/g) and large amount of macropores. High‐protein adsorption capacity (520mg/g) was achieved in the adsorption experiments of bovine serum albumin (BSA). Pore structure of silica spheres was demonstrated to be a crucial factor to determine the protein adsorption capacity. © 2007 American Institute of Chemical Engineers AIChE J, 2008
Free surface flow in the mixing zone of an annular centrifugal contactor
Authors: Wardle Kent E. , Allen Todd R. , Anderson Mark H. , Swaney Ross E.
Published: December 2007

The annular centrifugal contactor has been developed as the central piece of equipment for advanced liquid–liquid extraction processes for use in recycling spent nuclear fuel. While a sufficient base of experience exists to support successful operation of current contactor technology, a more complete understanding of the fluid flow within the contactor would enable further advancements in design and operation of future units. In particular, an important characteristic of the flow that is not well understood and which significantly complicates computational modeling of the contactor is the complex free surface flow in the annular mixing zone. This study presents the results of time‐dependent, multiphase computational fluid dynamics (CFD) modeling using the volume‐of‐fluid (VOF) interface tracking method to characterize the mixing zone in a model centrifugal contactor. Laser doppler velocimetry (LDV) measurements of the actual flow velocities within the contactor were also performed. The experimental results were compared with simulations using various turbulence modeling schemes. The CFD model predictions using a coarse grid large eddy simulation (LES) method are in good agreement with the experimental measurements and observations. © 2007 American Institute of Chemical Engineers AIChE J, 2008
Structure and electrochemical properties of polyamide and polyaniline
Authors: Ding Shihai , Chao Danming , Zhang Min , Zhang Wanjin
Published: December 2007

Electrochemical properties of well‐defined molecular structured polyamide with amine‐capped aniline pentamer in the main chain and conventional polyaniline were investigated and discussed. CV results suggest that the synthesized polyamide shows a relatively complicated redox process than conventional polyaniline during potential cycling. Differences in ESI characterization revealed that the synthesized polyamide exhibits higher electronic conductivity and lower resistance than the conventional polyaniline. The analysis of molecular configuration based upon the quantum chemistry calculation reveal that the difference in electrochemical activity and conductivity should be ascribed to the influence of system energy, skeleton conjugation, and the Fermi energy of the bipolaron model in the polymer molecules. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Preparation of interfacially compatibilized PP‐EPDM thermoplastic vulcanizate/graphite nanocomposites: Effects of graphite microstructure upon morphology, electrical conductivity, and melt rheology
Authors: Katbab A. A. , Hrymak A. N. , Kasmadjian K.
Published: December 2007

Electrically conductive PP/EPDM dynamically crosslinked thermoplastic vulcanizate (TPV)/expanded graphite (EG) has been successfully prepared via melt compounding of maleic anhydride grafted polypropylene (PP‐g‐MA)/EG masterbatch and a commercially available TPV material. Correlation between graphite microstructure, and electrical conductivity as well as melt rheological behavior has been studied. Natural graphite flake (NGF), graphite intercalated compound (GIC), and exfoliated graphite (EG) have been employed and compared. Scanning electron microscopy (SEM) showed the presence of 100–200 nm nanolayers in the structure of PP‐g/EG masterbatches, whereas thinner platelets (1.5–2.5 nm) were revealed by transmission electron microscopy (TEM). Better dispersion of the graphite nanolayers in the microstructure of TPV/PP‐g‐MA/EG composite was verified, as the 7.3 Å spacing between the aggregated graphite nanolayers could not be observed in the XRD pattern of this material. TPV/PP‐g/EG nanocomposites exhibited much lower conductivity percolation threshold (φc) with increased conductivity to 10−5 S/cm at EG wt % of 10. Higher nonlinear and nonterminal melt rheological characteristics of dynamic elastic modulus (G′) at low frequency region was presented by the TPV/PP‐g/EG nanocomposites, indicating the formation of nanoscopic conducting multiple networks throughout the continuous TPV matrix. Maleated PP was found to be much more effective in separating EG nanolayers which is attributed to the higher interfacial interaction between PP‐g‐MAH and EG, synergized with its multiporous structure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effects of epoxidized sunflower oil on the mechanical and dynamical analysis of the plasticized poly(vinyl chloride)
Authors: Bouchareb Badra , Benaniba Mohamed Tahar
Published: December 2007

Epoxidized soybean oil (ESBO), is one of the most commonly used epoxides because of its typical combined roles as a plasticizer and heat stabilizer. In this study, a novel plasticizer of poly(vinyl chloride) (PVC) resins, epoxidized sunflower oil (ESO), was synthesized, and its performance was evaluated. ESO was designed to act as a coplasticizer and a heat stabilizer like ESBO. ESO is used as organic coplasticizer for plasticized PVC containing Ca and Zn stearates as primary stabilizers and stearic acid as lubricant. Di‐(2‐ethylhexyl) phthalate (DEHP), a conventional plasticizer for PVC, was partially replaced by ESO. Mechanical properties (tensile and shore D hardness) were investigated. The performance of ESO to ESB0 (20 g) for comparison, indicated that ESO could be used as secondary plasticizer for PVC in combination with DEHP. All mechanical and dynamical properties of plasticized PVC sheets varied with the oxirane oxygen of the ESO. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Influence of wood fiber size on extrusion foaming of wood fiber/HDPE composites
Authors: Guo G. , Lee Y. H. , Rizvi G. M. , Park C. B.
Published: December 2007

Foaming of wood fiber/plastic composites (WPC) with a fine‐celled structure can offer benefits such as improved ductility and impact strength, lowered material cost, and lowered weight, which can enhance their utility in many applications. Although a great deal of attention is now being focused on these composites in the scientific literature, there are still numerous aspects of WPC processing that need elucidation. In this context, this article investigates the effects of wood fiber (WF) size on fine‐celled extrusion foaming of WPC in terms of cell size, cell size distribution, and foam density. The effects of WF size and coupling agent content on the viscosity of WPC are also investigated. The experimental results revealed that the small‐sized WF provides a better cell morphology, a smaller cell size, and a better cell uniformity in WPC foams. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Organomodified kaolin as a reinforcing filler for natural rubber
Authors: Sukumar Rugmini , Menon A. R. R.
Published: December 2007

China clay (kaolin) has been modified with sodium salt of rubber seed oil (SRSO). SRSO was characterized using X‐ray diffraction (XRD), infrared spectroscopy (FTIR), and differential thermal analysis (DTA). XRD of the unmodified and SRSO‐modified kaolins showed an increase in the d‐(001) spacing of kaolin platelets from 7.15 to 14 Å. FTIR spectroscopy indicated possible grafting of the organic moiety of rubber seed oil (RSO) onto the clay surface. DTA of the SRSO‐modified kaolin indicated that the SRSO is more strongly bound in a constraint environment within the lamellae of kaolin. Natural rubber (NR) mix containing 10 phr of SRSO‐modified kaolin was found to cure faster than that of a similar mix containing unmodified kaolin. NR vulcanizates containing SRSO‐modified kaolin showed considerable increase in tensile modulus, tensile strength, and elongation at break indicating its potential as an organomodified nanofiller. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Kenaf fiber/poly(ε‐caprolactone) biocomposite with enhanced crystallization rate and mechanical properties
Authors: Pan Pengju , Zhu Bo , Dong Tungalag , Serizawa Shin , Iji Masatoshi , Inoue Yoshio
Published: December 2007

Plant‐derived kenaf fiber (KF)‐reinforced poly(ε‐caprolactone) (PCL) biocomposites were successfully fabricated by the melt mixing technique. The crystallization behavior, morphology, and mechanical and dynamic mechanical properties of PCL/KF composites with various KF weight contents were investigated. The crystallization rate, tensile and storage moduli significantly improved as compared to the virgin polymer. The half times of PCL/KF composite (20 wt % fiber content) in isothermal crystallization at 40°C and 45°C reduced to 31.6% and 42.0% of the neat PCL, respectively. Moreover, the tensile and storage modulus of the composite are improved by 146% and 223%, respectively, by the reinforcement with 30% KF. The morphology evaluated by SEM indicates good dispersion and adhesion between KF and PCL. Overall, these findings reveal that KF can be a potential reinforcement for the biodegradable polymer composites owing to its good ability to improve the mechanical properties as well as crystallization rate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Ground particle size influence on the swelling of a copolymer of AA/AMPS in water
Authors: Rosa Fátima , Bordado João , Casquilho Miguel
Published: December 2007

The influence of the ground particle size on the swelling behavior of a copolymer of AA/AMPS in water was observed to determine the best size considering water absorbency in view of fastest and highest equilibrium swelling. The copolymer gel, from acrylamide and 2‐acrylamido‐2‐methyl‐propanosulfonic acid and synthesized in the presence of N,N‐methylene‐bis‐acrylamide, was obtained by a radical solution technique, and identified by FTIR spectroscopy. By grinding, various particle diameters were obtained, and then separated by sieves. Studies of dynamic and equilibrium swelling in deionized water at 20°C showed the influence of the particle size on the kinetics of swelling and its equilibrium swelling capacity. A mathematical model for the absorption, including diffusion and relaxation modes, permitted to assess the absorption mechanism, and offered quantitative information about water diffusivity in the copolymer. The fastest swelling was obtained with diameters of 22.5–215 μm. Particle sizes ranging from 67.5 to 355 μm yielded the greatest equilibrium swelling, with mass ratios of about 1100. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Tensile behavior of polypropylene blended with bimodal distribution of styrene‐ethylene‐butadiene‐styrene particle size
Authors: Mae Hiroyuki , Omiya Masaki , Kishimoto Kikuo
Published: December 2007

The objective is to characterize the effects of the bimodal distribution of rubber particles and its blend ratio on the mechanical properties of the thermoplastic polypropylene blended with two different styrene‐ethylene‐butadiene‐styrene triblock copolymer at the intermediate and high strain rates. Tensile tests are conducted at the nominal strain rates from 3 × 10−1 to 102 (1/s). Phase morphology is investigated to estimate the bimodal rubber particle size distribution. In addition, the in situ observation is conducted during uniaxially stretching within transmission electron microscopy step by step to investigate the deformation events depending on the elongation of samples. The elastic modulus increased gradually as the blend ratio of large rubber particle increased. An increase in the rupture strain and the strain energy up to failure was found for the bimodal rubber particle distributed blend system where the blend ratios of small rubber particle and large rubber particle were same. This is because the smaller particles dominant blend systems show the bandlike craze deformation while the localized plastic deformation is taken place in the larger particles dominated blend systems. The synergistic effect of these rubber particles gives rise to a strong increase in the ductility of these bimodal rubber particle distributed polypropylene systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Structure and property characterization of nanograde core‐shell polyurethane/polyacrylate composite emulsion
Authors: Chai Shu Ling , Tan Hui Min
Published: December 2007

Anionic aqueous polyurethane dispersion was synthesized through self‐emulsifing method from cycloaliphatic isophorone diisocyanate (IPDI) and dimethylolpropionic acid (DMPA). The carboxyl acid group in DMPA was used to make the polyurethane dispersible. The polyurethane/polyacrylate (PU/PA) composite particles were also prepared by seeded surfactant‐free emulsion polymerization; the cycloaliphatic polyurethane aqueous dispersion was used as seed particles. The structures and properties of the composite emulsion as well as the physical mixture of polyurethane dispersion and polyacrylate emulsion were characterized by FTIR, DSC, dynamic light scattering, TEM, X‐ray photoelectron spectroscopy (ESCA), and electronic tensile machine. The results showed that the synthesized PU/PA composite emulsion was found to form inverted core‐shell structure with polyacrylate as the core and with polyurethane as the shell, and its diameter of particles is in the range of nanograde, the crosslinking reaction was existed in composite emulsion. The intimate molecular mixing of crosslinking polymers are also claims to result in a superior balance of properties compared to physical blends of polyurethane dispersion and acrylate emulsion. The crosslinking mechanism of PU/PA composite emulsion was also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Preparation and physical properties of photopolymer/SiO2 nanocomposite for rapid prototyping system
Authors: Chiu Shih‐Hsuan , Wu Dien‐Chi
Published: December 2007

A photopolymer material was applied in liquid rapid prototyping (RP) machine. The prototype fabricated from photopolymer was difficult for storage due to volumetric shrinkage and deformation during curing. The prototype fabricated from photopolymer suffers from the volumetric shrinkage during curing and the continuing deformation for a creeping period after curing. Therefore, we used nano‐SiO2 as a major additive to modify the physical properties of photopolymer. We also added appropriate dispersant to make nanoparticles distribute uniformly in order to reduce the phase separation in composite material. The experimental results showed that photopolymer/SiO2 nanocomposite can improve tensile strength and hardness by about 50% and offers better dimensional stability. Photopolymer/SiO2 nanocomposite can also increase the degradation temperature and shorten manufacturing time for RP processing. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Genetically Encoded Bioluminescent Indicator for ERK2 Dimer in Living Cells
Authors: Kaihara Asami , Umezawa Yoshio
Published: December 2007

In this study, a genetically encoded bioluminescent indicator for ERK2 dimer was developed with the split Renilla luciferase complementation method, in which the formation of ERK2 dimer induces a spontaneous emission of bioluminescence in living cells. In response to extracellular stimuli, such as epidermal growth factor (EGF) or 17β‐estradiol (E2), extracellular signal‐regulated kinase 2 (ERK2) is phosphorylated by its upstream kinase MEK, and also phosphorylates its substrates in various regions of the cell, including the nucleus. Phosphorylated ERK2 is led to form its dimer, thereby transporting itself into the nucleus. We demonstrated with the indicator that stimulation with EGF or E2 induces the formation of ERK2 dimer in living MCF‐7 cells. The dynamics of this dimer formation was examined and discussed.
Induction of Optical Activity in an Oligothiophene Synchronized with pH‐Sensitive Folding of Amylose
Authors: Sanji Takanobu , Kato Nobu , Tanaka Masato
Published: December 2007

Control of the helical sense in α‐sexithiophene (6T) through pH‐responsive wrapping with left‐handed‐helical amylose is demonstrated. A change in pH of the medium caused a significant conformational change in amylose as the host polymer, which resulted in either supramolecular complexation with 6T as the guest molecule to induce optical activity or decomplexation leading to loss of optical activity. Furthermore, we observed that chirality reversal in 6T does not require hosts of opposite helical chirality, but can be made possible simply by taking advantage of the pH sensitivity of the amylose folding, which is dependent on the pH history of the aqueous medium. In helical amylose, 6T assumes a clockwise‐twisted conformation when the pH is changed from acidic to neutral, but assumes an anticlockwise‐twisted conformation when the aqueous solution is acidified from very basic conditions.
Central venous catheterization—An anatomical review of a clinical skill, Part 2: Internal jugular vein via the supraclavicular approach
Authors: Boon J.M. , Van Schoor A.N. , Abrahams P.H. , Meiring J.H. , Welch T.
Published: December 2007

The safe and successful performance of a central venous catheterization (CVC) requires a specific knowledge of anatomy in addition to a working knowledge. Misunderstanding the anatomy may result in failure or complications. This review aims to aid understanding of the anatomical framework, pitfalls, and complications of CVC of the internal jugular veins. CVC is common practice amongst surgeons, anesthesiologists, and emergency room physicians during the preparations for major surgical procedures such as open‐heart surgery, as well as for intensive care monitoring and rapid restoration of blood volume. Associated with this technique are certain anatomical pitfalls and complications that can be successfully avoided if one possesses a thorough knowledge of the contraindications, regional anatomy, and rationale of the technique. Clin. Anat. 21:15–22, 2008. © 2007 Wiley‐Liss, Inc.
Evaluation of methods to reduce formaldehyde levels of cadavers in the dissection laboratory
Authors: Whitehead Mark C. , Savoia Maria C.
Published: December 2007

Dissection of conventionally embalmed cadavers exposes students, staff, and faculty to formaldehyde, a probable carcinogen. Therefore, prudent practices should seek to minimize formaldehyde exposure. In this study, we evaluated two commercially available chemicals, InfuTrace and Perfect Solution, for their effectiveness in reducing ambient formaldehyde levels. Four cadavers embalmed conventionally with formaldehyde and/or with the above agents were compared for their formaldehyde levels under conditions that strictly controlled for air circulation and for locations and methods of testing, and during activities that simulated student dissecting. For InfuTrace, one cadaver was reinfused with InfuTrace after initial standard perfusion with formaldehyde; a second cadaver had InfuTrace injected into the thoracic and abdominal body cavities after formaldehyde perfusion. For Perfect Solution, the product was used for embalming a third cadaver in lieu of formaldehyde. For a control, a fourth cadaver was embalmed with the standard formaldehyde solution. Testing of personal and ambient room air samples and of fluid obtained from the cadavers was performed and analyzed in a blinded fashion. Results indicated that both Perfect Solution, substituted for standard formaldehyde embalming, and InfuTrace infused through the vasculature after formaldehyde embalming, resulted in lower concentrations of formaldehyde than embalming with formaldehyde solution alone or in combination with body cavity injection of InfuTrace. These differences in formaldehyde concentrations are consistent across measuring methods, for example, of room air, of breathing zone air during cadaver handling and dissection, and of liquid samples obtained from the cadavers. Perfect Solution yielded suboptimum fixation and a different texture, color, and smell than the formaldehyde treatments. Clin. Anat. 21:75–81, 2008. © 2007 Wiley‐Liss, Inc.
Arterial supply to the sciatic nerve in the gluteal region
Authors: Georgakis Effrossyni , Soames Roger
Published: December 2007

The arterial supply to the sciatic nerve was investigated in 20 human lower limbs (10 right, 10 left) from 20 cadavers (14 females, aged 84 ± 9.6 years, range 66–95 years: 6 males, aged 80 ± 8.2 years, range 70–90 years). In all limbs examined at least 1 sciatic artery could be identified supplying the sciatic nerve in the gluteal region. In total 28 sciatic arteries were identified, of which 14 arose from the medial circumflex femoral artery, 11 from the inferior gluteal artery, 2 from the first perforating artery, and 1 from the internal pudendal artery. In 5 limbs, 2 sciatic arteries were observed, being independent branches from the medial circumflex femoral and inferior gluteal arteries in 4 limbs and separate branches of the medial circumflex femoral artery in 1 limb. In 1 limb, 4 sciatic arteries were observed: 1 from the inferior gluteal artery, 2 from the medial circumflex femoral artery, and 1 from the first perforating artery. In the remaining 14 limbs a single sciatic artery was observed, which in one case arose from the internal pudendal artery, a previously unreported observation. Clin. Anat. 21:62–65, 2008. © 2007 Wiley‐Liss, Inc.
A New Method for Determination of the Adsorption Isotherm of SDS on Polystyrene Latex Particles Using Conductometric Titrations
Authors: Nodehi A. , Moosavian M. A. , Haghighi M. N. , Sadr A.
Published: December 2007

Monodisperse polystyrene (PS) latex particles were prepared through a conventional batch emulsion polymerization procedure. After cleaning, the latex was subjected to a surfactant titration by sodium dodecyl sulfate (SDS) and the conductivity was monitored. Using the break point in the conductivity‐concentration curve, the adsorption area of the surfactant molecules at saturation, As, was determined as 46 Å2 per SDS molecule. In order to determine the contribution of the different ionic species to the conductivity, a simple model based on experimental conductivity measurements was developed. The degrees of counterion binding to the micelles and to the surfactant anions adsorbed onto polymer particles were calculated as 0.770 and 0.849, respectively. The Langmuir adsorption isotherm was determined for the adsorption of SDS onto PS latex particles with Γ∞ = 7.257 · 10–10 mol/cm2 and K = 1.208 · 105 cm3/mol.
Oxidation of Benzene to Maleic Anhydride in a Fluidized Bed Reactor
Authors: Uraz C. , Atalay S.
Published: December 2007

In this project, the selective oxidation of benzene to maleic anhydride (MAN) was studied. Gas phase catalytic oxidation of benzene was carried out in a laboratory scale fluidized bed reactor on six different types of catalysts, which have different compositions. Effects of temperature, flow rates of benzene and air and catalyst type on the reaction selectivity were investigated at atmospheric pressure. The experiments were performed over a temperature range of 325 to 400 °C, a space‐time (W/FA0) range from 11.28 × 105 to 31.9 × 105 g s mol–1, and benzene/air mole ratio changes between 0.0109 and 0.0477. It was seen that conversion of benzene to MAN increased with increasing temperature for the catalysts supported by silica gel, aluminum oxide and titanium oxide. From the results it was found that conversion increased with increasing flow rate of air. When the comparison of the catalysts were made, it could be said that catalysts supported by silica gel showed higher MAN conversions. So it can be concluded that catalysts supported by silica gel were more suitable catalysts for benzene oxidation to MAN in a fluidized bed reactor.
Simulation of Barium Sulfate Precipitation using CFD and FM‐PDF Modeling in a Continuous Stirred Tank
Authors: Wang Z. , Zhang Q. H. , Yang C. , Mao Z.‐S. , Shen X. Q.
Published: December 2007

A mixing‐precipitation model combining computational fluid dynamics (CFD), finite‐mode PDF (probability density function) model, population balance and kinetic modeling has been proposed to simulate the barium sulfate precipitation process in a continuous stirred tank agitated by a Rushton turbine. The effect of various operating conditions such as impeller speed, feed concentration, feed position and mean residence time on the barium sulfate precipitation process is clearly demonstrated. It is shown that the mean crystal size increases by increasing the impeller speed and mean residence time. However, when the feed concentration is increased, the mean crystal size decreases. The predictions are in reasonable agreement with the experimental data in the literature.
Determining Cyclone Particle Holdup by Pressure Drop for a CFB Boiler
Authors: Li S. H. , Zhang H. , Yang H. R. , Yang S. , Lu J. F. , Yue G. X.
Published: December 2007

An experimental study was conducted to assess the possibility of determining particle holdup by measuring the pressure drop of a conventional cyclone used in a circulating fluidized bed (CFB) boiler. It was found that within a wide range of inlet solid concentrations, i.e., 0.54–4.42 kg/kg‐gas, the cyclone pressure drop increased linearly with inlet solid concentration at a given gas velocity, while the pressure drop between the dust exit and the vortex finder of the cyclone remained almost constant. Since particle holdup increases virtually linearly with solid flow rate, the particle holdup in the cyclone can be derived from the cyclone pressure drop, and therefore, an equation set was proposed to calculate the particle holdup from the cyclone pressure drop.
Reaction Kinetics of Soybean Oil Transesterification Using Heterogeneous Metal Oxide Catalysts
Authors: Singh A. K. , Fernando S. D.
Published: December 2007

Homogeneous acid or base catalysts dissolve fully in the glycerol layer and partially in the fatty acid methyl ester (biodiesel) layer in the triglyceride transesterification process. Heterogeneous (solid) catalysts, on the other hand, can prevent catalyst contamination making product separation much simpler. In the present work, the transesterification kinetics of five different solid catalysts with soybean oil is presented. It is found that heterogeneous catalysts require much higher temperatures and pressures to achieve acceptable conversion levels compared to homogeneous catalysts. Subsequent to preliminary investigations, transesterifications were conducted for selected high performance solid catalysts, i.e., MgO, CaO, BaO, PbO, and MnO2 in a high pressure reactor up to a temperature of 215 °C. The yield of the fatty acid methyl esters and the kinetics (rate constant and order) of the reaction are estimated and are compared for each catalyst.
Radial Gas Mixing in a Fluidized Bed with a Multi‐Horizontal Nozzle Distributor using Response Surface Methodology
Authors: Chyang C.‐S. , Qian F.‐P. , Chiou H.‐Y.
Published: December 2007

The gas mixing in the radial direction within a fluidized bed equipped with a multi‐horizontal nozzle distributor was studied using response surface methodology (RSM), which enables the examination of parameters with a moderate number of experiments. All experiments were carried out in a circular fluidized bed of 0.29 m I.D. cold model fluidized bed. The distributor is placed beside twenty‐two horizontal nozzles that are arranged in three concentric circles with all existing discharge directed clockwise. The tracer gas (CO2) was discharged into the bed as a tracer gas and the analysis was performed with a gas chromatograph. In order to compare the different internal circulations, the tracer gas was discharged in the center area or annular area of the bed. In RSM, the static bed height, superficial velocity and the open area ratio of the distributor are chosen as the research variables, and the standard deviation of the time averaged radial tracer concentration is used as the objection function. A mathematical model for the gas mixing as a function of the operating parameters was empirically proposed. The results show that the standard deviation of time averaged radial tracer concentration is well correlated with the operating and geometry parameters, (U – Umf)/Umf, Hs/D and ψd, and that the tracer gas injected to the center position has a better dispersion than when injected to the annular position. This model can be used for optimizing the design of fluidized bed reactors at a required performance level.
Simulation and Analysis of a Single‐Effect Thermal Vapor‐Compression Desalination System at Variable Operation Conditions
Authors: Ji J. G. , Wang R. Z. , Li L. X. , Ni H.
Published: December 2007

A mathematical model is developed to analyze a single‐effect thermal vapor compression (TVC) desalination system. The effects of the variation of operation conditions such as the intake seawater temperature and the mass flow rate of cooling water on the system performance are investigated for a specific desalination unit. The system performance is found to decrease when the intake seawater temperature is different from the design value. By adjusting the mass flow rate of cooling water, a better system performance can be obtained when the intake seawater temperature differs from the design conditions. Decreasing the cooling water flow rate to values lower than the design value can lead to a better performance when the intake seawater temperature is lower than the design value, and the system performance reaches a peak point when the cooling water flow rate decreases to a definite level. A better performance can also be obtained by increasing the cooling water flow rate to values higher than design value, when the intake seawater temperature is higher than the design value and the system performance also reaches a peak point when the cooling water flow rate increases to a definite level.
A Digital Imaging Technique for the Analysis of Local Inhomogeneities from Agitated Vessels
Authors: Visuri O. , Laakkonen M. , Aittamaa J.
Published: December 2007

A novel, cheap and simple technique for the analysis of the mixing properties from a stirred vessel is introduced. The technique is based on a digital imaging technique and the analysis can be undertaken based on the properties of the image. Using this technique, it is easy to analyze mixing inhomogeneities. Test measurements with non‐Newtonian viscous, aqueous xanthan solutions and fluids as well as liquid‐particle suspensions showed that the developed method is a quick and quantitative tool for the analysis of local mixing inhomogeneities, mixing times and particle suspension speeds.
Microstructured Reactors in Heterogenous Catalysis
Authors: Klemm E. , Döring H. , Geisselmann A. , Schirrmeister S.
Published: December 2007

A number of heterogeneously catalyzed reactions, mainly gas‐phase reactions, have been performed previously at a laboratory scale and a successful proof of concept was achieved. Since the beginning of this century, there has been a shift in focus on the transfer from laboratory scale to production scale. In particular, this review deals with the technical concepts and economic aspects involved in such a shift. Heterogenously catalyzed gas‐phase and liquid‐phase processes are discussed separately. The preparation of wall catalysts is a key technology in both cases and is described in an additional subsection. Finally, an evaluation of the developmental status is given.
Determination of Mixing Times with Helical Ribbon Impeller for Non‐Newtonian Viscous Fluids Using an Advanced Imaging Method
Authors: Chhabra R. P. , Bouvier L. , Delaplace G. , Cuvelier G. , Domenek S. , André C.
Published: December 2007

New results on mixing times for viscous Newtonian and non‐Newtonian fluids being homogenized with a helical ribbon impeller are presented. In particular, a recently developed technique to determine the macromixing kinetics of an impeller in a transparent vessel was applied to investigate the effects of rheological properties on mixing times. Significant differences were observed in the mixing times for viscous Newtonian and non‐Newtonian fluids. Based on the new data obtained in this work, a correlation incorporating the elastic effects is proposed in terms of a Weissenberg number for predicting the mixing time as a function of the Reynolds number and the system geometry.
Multiperiod Investment Models for the Gradual Reconstruction of Chemical Processes
Authors: Novak‐Pintaric Z. , Kravanja Z.
Published: December 2007

A multiperiod mixed‐integer nonlinear programming (MINLP) model is presented for the planning of an optimal investment policy for the gradual retrofit of chemical plants over a specified time frame. This approach can be applied when the available funds are insufficient to perform the optimal reconstruction in one step. Through gradual improvements, the process progressively approaches its optimum with considerably lower requirements for new capital, while still exhibiting an attractive increase in economic performance. In the proposed multiperiod problem for gradual retrofit, certain amounts of capital enter into the time periods for the gradual increase of equipment in order to improve the performance of the process, e.g., to lead to an increase in conversion or energy recovery. This capital may arise from internal sources within the company or can be borrowed. The financial benefits resulting from the improvements at the end of the time period can be reinvested for the additional reconstruction over the next development phases. In this way, self‐sustained capital generation for future reconstruction is achieved, and any additional funds required are minimized. The objective function of the proposed problem is formulated as the net present worth of the gradually retrofitted system. This enables several techno‐economic analyses to be performed. The proposed multiperiod investment strategies are illustrated by an investment planning example for the retrofit of a heat‐exchanger network.
Precursor Approach to Lanthanide Dioxo Monocarbodiimides Ln2O2CN2 (Ln=Y, Ho, Er, Yb) by Insertion of CO2 into Organometallic Ln–N Compounds
Authors: Zeuner Martin , Pagano Sandro , Schnick Wolfgang
Published: December 2007

We present two organometallic precursor approaches leading to the hitherto‐unknown dioxo monocarbodiimides (Ln2O2CN2) of the late lanthanides Ho, Er, and Yb as well as yttrium. One involves insertion of CO2, and the other one is a straightforward route using a molecular single‐source precursor. To this end the reactivity of the activated amido lanthanide compound [(Cp2ErNH2)2] towards carbon dioxide absorption under supercritical conditions was studied. Selective insertion of CO2 into the amido complex yielded the single‐source precursor [Er2(O2CN2H4)Cp4], which was characterized by vibrational spectroscopy and thermal and elemental analyses. Ammonolysis of this amorphous compound at 700 °C affords Er2O2CN2. To gain deeper insight into the structural characteristics of the amorphous precursor, a similar molecular carbamato complex was synthesized and fully characterized. X‐ray structure analysis of the dimeric complex [Cp4Ho2{μ‐η1:η2‐OC(OtBu)NH}] shows an unusual bonding mode of the tert‐butylcarbamate ligand, which acts as both a bridging and side‐on chelating group. Ammonolysis of this compound also yielded dioxo monocarbodiimides, and therefore the crystalline carbamato complex turned out to be an alternative precursor for the straightforward synthesis of Ln2O2CN2. Analogously, the dioxo monocarbodiimides of Y, Ho, Er, and Yb were synthesized by this route. The crystal structures were determined from X‐ray powder diffraction data and refined by the Rietveld method (Ln=Ho, Er). Further spectroscopic characterization and elemental analysis evidenced the existence of phase‐pure products. The dioxo monocarbodiimides of holmium and erbium crystallize in the trigonal space group P$\bar 3$m1. According to X‐ray powder diffraction, they adopt the Ln2O2CN2 (Ln=Ce–Gd) structure type.
Zn[BPO4(OH)2]: A Zinc Borophosphate with the Rare Moganite‐Type Topology
Authors: Huang Ya‐Xi , Prots Yurii , Kniep Rüdiger
Published: December 2007

A novel zinc borophosphate Zn[BPO4(OH)2] with moganite‐type topology (a rare polymorph of silica) has been prepared from a mixture of ZnO, B2O3, and P2O5 by hydrothermal treatment at 443 K. The crystal structure was determined from single‐crystal X‐ray data (orthorhombic, Pbcn (no. 60), a=915.07(3), b=897.22(3), c=1059.19(3) pm, V=869.62(5)×106 pm3, Z=8, R1=0.028, wR2=0.075). The crystal structure comprises unbranched vierer‐single borophosphate chains running along [010] and interconnected via ZnO2(OH)2‐tetrahedra by sharing common vertices. The resulting topology of the three‐dimensional tetrahedral framework structure is described by the Schläfli symbol (42.62.82)(4.64.8)2. Although showing Zn in a tetrahedral coordination, the title compound does not belong to the group of zincoborophosphates but is a special case of a borophosphate containing vierer single rings of tetrahedra with the sequence Zn‐B‐Zn‐P.
The Local Crystal Chemistry and Dielectric Properties of the Cubic Pyrochlore Phase in the Bi2O3—M2+O—Nb2O5 (M2+: Ni2+ and Mg2+) Systems.
Authors: Nguyen Binh , Liu Yun , Withers Ray L.
Published: December 2007

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