bluuebunny/crossref_metadata_2025 huggingface dataset:
Sexual dimorphism in large‐bodied primates: The case of the subfossil lemurs
Authors: Godfrey Laurie R. , Lyon Sarah K. , Sutherland Michael R.
Published: August 2005

Large body size has evolved repeatedly in the order Primates, not merely among anthropoids but also among prosimians. Whereas high degrees of sexual size dimorphism characterize many of the large‐bodied anthropoids, this is not the case for extinct large‐bodied lemurs. This paper uses finite mixture analysis and other techniques to ascertain just how much skull length dimorphism might be embedded in the generally unimodal distributions of skull lengths of giant extinct lemurs from single localities, and then compares these results with known skull length dimorphisms in extant lemurs and large‐bodied catarrhines. We show that low levels of skull length sexual dimorphism (or none at all) characterize subfossil lemurs, and we explore several possible explanations for this phenomenon. Traditional explanations of sexual size dimorphism generally focus on body size or mating systems. These are not sufficient to explain the variation in sexual dimorphism that can be observed in the order Primates. © 1993 Wiley‐Liss, Inc.
Temporal craniometric changes from the Jomon to the Modern period in western Japan
Authors: Nakahashi Takahiro
Published: August 2005

Temporal changes in morphometric features of human cranial remains from the late Jomon period (1500 B.C.–300 B.C.) to the Modern period (1900–1950 A.D.) in western Japan are examined. The results of univariate and multivariate analysis indicate that the Yayoi people (300 B.C.–300 A.D.), characterized by high faces and tall stature, show morphological discontinuity with the earlier Jomon people, who exhibit lower faces and shorter stature. This discontinuity contrasts with the relatively continuous changes among populations after the Yayoi. Comparing these changes with those documented in the Kanto region of eastern Japan indicates there are significant regional differences in the degree and rate of transformation in certain cranial features, especially facial height, between the two regions. Differences in cranial shape between the two regions become apparent during the Yayoi period and these differences tend to diminish thereafter. The most plausible explanation for these observed changes is the introduction of new genes, coinciding with the arrival of new immigrants from the Asian continent in the northern Kyushu‐Yamaguchi region at the beginning of the Yayoi period. Further testing of this hypothesis will be necessary before definitive conclusions can be reached regarding the appearance of modern Japanese. © 1993 Wiley‐Liss, Inc.
New method of three‐dimensional analysis of bipedal locomotion for the study of displacements of the body and body‐parts centers of mass in man and non‐human primates: Evolutionary framework
Authors: Tardieu Christine , Aurengo André , Tardieu Bernard
Published: August 2005

The current biomechanical interpretation of the chimpanzee's bipedal walking argues that larger lateral and vertical displacements of the body center of mass occur in the chimpanzee's “side‐to‐side” gait than in the human striding gait. The evolutionary hypothesis underlying this study is the following: during the evolution of human bipedalism one of the necessary changes could have been the progressive reduction of these displacements of the body center of mass. In order to quantitatively test this hypothesis, it is necessary to obtain simultaneously the trajectories of the centers of mass of the whole body and of the different body parts. To solve this problem, a new method of three‐dimensional analysis of walking, associated with a volumetric modelling of the body, has been developed based on finite‐element modelling. An orthogonal synchrophotographic device yielding four synchronous pictures of the walking subject allows a qualitative analysis of the photographic sequences together with the results of their quantitative analysis. This method was applied to an adult man, a 3‐year‐old girl and a 9‐year‐old male chimpanzee.

Our results suggest that the trajectory of the body center of mass of the human is distinguished from that of the chimpanzee not by a lower movement amplitude but by the synchronization of the transverse and vertical displacements into two periodic curves in phase with one another. The non‐human primate uses its repertoire of arboreal movements in its bipedal terrestrial gait, provisionally referred to as a “rope‐walker” gait. We show that the interpretation of a “side‐to‐side” gait is not applicable to the chimpanzee. We argue that similarly this interpretation and the initial hypothesis presuppose a basic symmetric structure of the gait, in relation to the sagittal plane of progression, similar to the human one. This lateral symmetry of the right and left displacements of the center of gravity, in phase with the right and left single supports of walking, is probably a very derived feature of the human gait. We suggest that low lateral and vertical displacements of the body center of mass are not indicative of a progressive bipedal gait and we discuss the new evolutionary implications of our results. © 1993 Wiley‐Liss, Inc.
Nuclear DNA polymorphisms in a wild population of yellow baboons (Papio hamadryas cynocephalus) from Mikumi National Park, Tanzania
Authors: Rogers J. , Kidd K. K.
Published: August 2005

Yellow baboons (Papio hamadryas cynocephalus) from Mikumi National Park, Tanzania were studied for polymorphisms in nuclear DNA. The study population consists of four social groups that inhabit overlapping home ranges and exchange males. As a result, these groups are considered to be members of a single interbreeding population. Human DNA clones were used as probes to screen five loci (AT3, REN, HEXB, VIM, and APOB) for restriction fragment length polymorphisms (RFLP). A total of 14 polymorphisms, at least one at each locus, was detected in a panel of 27 baboons tested using six restriction enzymes for each locus. Eleven of these RFLP systems have average heterozygosity values greater than 0.40. This initial screening demonstrates that human DNA clones can be used to detect significant numbers of informative DNA polymorphisms in single‐copy nuclear genes of this species and suggests that the average proportion of nucleotides polymorphic across nuclear loci in this population may be between 1.0% and 1.3%. © 1993 Wiley‐Liss, Inc.
Gut morphology of Callithrix nigriceps and Saguinus labiatus from western Brazilian Amazonia
Authors: Ferrari Stephen F. , Lopes M. Aparecida , Krause E. Alexandra K.
Published: August 2005

Quantitative data on the gut proportions of the recently‐described black‐headed marmoset (Callithrix nigriceps) from western Brazilian Amazonian are presented. Like other marmosets, C. nigriceps exhibits a relatively large caecum and colon associated with adaptations for gummivory. The degree of gut specialisation recorded is greater than that for any other platyrrhine for which quantitative data are available. Gum was found in the stomach contents of all four individuals examined, although the fruit/seeds of as many as seven different plant taxa were also encountered, in addition to insects of six different orders. Gut proportions of two Saguinus labiatus from the same region were typical of the more frugivorous tamarins, and stomach contents included only fruit and insects. Relative gut proportions of both species were closely similar to those of congeners from the same region. © 1993 Wiley‐Liss, Inc.
Mitochondrial DNA analysis in Tibet: Implications for the origin of the Tibetan population and its adaptation to high altitude
Authors: Torroni Antonio , Miller Julie A. , Moore Lorna G. , Zamudio Stacy , Zhuang Jianguo , Droma Tarshi , Wallace Douglas C.
Published: August 2005

Mitochondrial DNAs (mtDNAs) of 54 Tibetans residing at altitudes ranging from 3,000–4,500 m were amplified by polymerase chain reaction (PCR), examined by high‐resolution restriction endonuclease analysis, and compared with those previously described in 10 other Asian and Siberian populations. This comparison revealed that more than 50% of Asian mtDNAs belong to a unique mtDNA lineage which is found only among Mongoloids, suggesting that this lineage most likely originated in Asia at an early stage of the human colonization of that continent. Within the Tibetan mtDNAs, sets of additional linked polymorphic sites defined seven minor lineages of related mtDNA haplotypes (haplogroups). The frequency and distribution of these haplogroups in modern Asian populations are supportive of previous genetic evidence that Tibetans, although located in southern Asia, share common ancestral origins with northern Mongoloid populations. This analysis of Tibetan mtDNAs also suggests that mtDNA mutations are unlikely to play a major role in the adaptation of Tibetans to high altitudes. © 1994 Wiley‐Liss, Inc.
Growth status of school‐age Mayan children in Belize, Central America
Authors: Crooks Deborah L.
Published: August 2005

This paper reports the growth status of a sample of Mopan Maya school children living in a rural village in Belize. These children exhibit a growth pattern typical of chronic undernutrition, in that a high percentage are stunted (66%), but virtually none are wasted by WHO criteria. The Belize Maya children are compared to four other Amerindian groups and found to be shorter and lighter than a semi‐urban group from Guatemala, but taller and heavier than three rural groups from Guatemala and Mexico. The Belize children exhibit the largest arm circumferences among all five groups. This pattern of growth is discussed in light of current ideas concerning the contribution of genetics vs. environment to childhood growth and population wellbeing. © 1994 Wiley‐Liss, Inc.
Mechanical and spatial determinants of Paranthropus facial form
Authors: McCollum Melanie A.
Published: August 2005

It is well documented in the anthropological literature that the distinctive morphology of the “robust” hominid facial skeleton reflects its dietary specialization. Rak (1983) has provided the most comprehensive evaluation of Paranthropus facial morphology and this important study concluded that bone strain generated during mastication was responsible for the scaling of measures of facial height and breadth. The present study evaluated Rak's analysis by examining the relationship between bizygomatic breadth and facial height in an ontogenetic series of Pan and Gorilla crania. Results of this analysis indicate that facial height and breadth dimensions were not mechanically scaled in the “robust” australopithecines. Structural analysis of African ape facial maturation was also used to examine alternative spatial methods of malar elongation in Paranthropus. It is concluded that the increased height of the malar region in these specimens is not related to either vertical expansion of the posterior facial skeleton or to expansion of the temporal fossa. Malar elongation is, however, consistent with a derived pattern of facial growth in crania possessing a thickened hard palate. © 1994 Wiley‐Liss, Inc.
Heterochrony and sexual dimorphism in the pigtailed macaque (Macaca nemestrina)
Authors: German R. Z. , Hertweck D. W. , Sirianni J. E. , Swindler D. R.
Published: August 2005

Somatic growth is not a simple linear process with a constant rate of growth. The most successful attempts to quantify growth as a function of age or size have employed nonlinear techniques. Sexual dimorphism of primate growth, weight vs. age, was examined using nonlinear models with Sirianni and Swindler's ([1985] Growth and Development of the Pigtailed Macaque, Boca Raton, FL: CRC Press) growth data on the pigtailed macaque (Macaca nemestrina). The best fit of several exponential growth models was the Gompertz curve:

Different multiple phase models were also fit, where each phase represents a distinct exponential component. The two‐phase models proved to be the best (R2 = .0.84 for females, 0.91 for males), suggesting that there are two growth spurts, one in infancy and one at puberty. The timing of the beginning and end of the first spurt is the same in males and females, but the rate, and value of the asymptote for this phase, is greater in males. The timing of the second spurt is earlier, and the rate of growth for this spurt is smaller in females than males. The sexual dimorphism in these species is not a simple rate change, but a complex interaction of timing and rate over the entire period of growth. It would be impossible to separate these entities with a linear, polynomial, or single‐phase model of the data. While these data and results complement much of the existing work on adult dimorphism, they also emphasize the vital role that ontogenetic data have in elucidating the underlying evolutionary mechanisms that generate sexual dimorphism. © 1994 Wiley‐Liss, Inc.
Pendular activity of human upper limbs during slow and normal walking
Authors: Webb David , Tuttle Russell H. , Baksh Michael
Published: August 2005

When walking at normal and fast speeds, humans swing their upper limbs in alternation, each upper limb swinging in phase with the contralateral lower limb. However, at slow and very slow speeds, the upper limbs swing forward and back in unison, at twice the stride frequency of the lower limbs. The change from “single swinging” (in alternation) to “double swinging” (in unison) occurs consistently at a certain stride frequency for agiven individual, though different individuals may change at different stride frequencies. To explain this change in the way we use our upper limbs and individual variations in the occurrence of the change, the upper limb is modelled as a compound pendulum. Based on the kinematic properties of pendulums, we hypothesize that the stride frequency at which the change from “single swinging” to “double swinging” occurs will be at or slightly below the natural pendular frequency (NPF) of the upper limbs.

Twenty‐seven subjects were measured and then filmed while walking at various speeds. The mathematically derived NPF of each subject's upper limbs was compared to the stride frequency at which the subject changed from “single swinging” to “double swinging.” The results of the study conform very closely to the hypothesis, even when the NPF is artificially altered by adding weights to the subjects' hands. These results indicate that the pendulum model of the upper limb will be useful in further investigations of the function of the upper limbs in human walking. © 1994 Wiley‐Liss, Inc.
Subvertical grooves of interproximal facets in neandertal posterior teeth
Authors: Villa Giuliano , Giacobini Giacomo
Published: August 2005

Subvertical grooves, located on the interproximal facets of most Neandertal posterior teeth, are less frequently noted on the teeth of other hominids, including modern humans. These grooves, 0.1–0.5 mm in width, are strictly localized within the facet area. Scanning electron microscopic (SEM) examination of grooves present on Neandertal teeth from Caverna delle Fate (Liguria, Italy) and Genay (Côte d'Or, France) demonstrated that they were produced during the life of these individuals. Characteristics of the groove surface suggest an erosion‐abrasion mechanism of formation.

These grooves, which developed in parts of the dentition exposed to marked stress, originated in areas characterized by changes in the orientation of enamel prism bundles (i.e., Hunter‐Schreger bands). Observations carried out on modern human molars showed a subvertical disposition of these bands near interproximal ridges facilitating subvertical microfractures. Possible correlations between enamel structure, masticatory stress, and interproximal groove formation in Neandertals are discussed. © 1995 Wiley‐Liss, Inc.
Sex determination in Miocene catarrhine primates
Authors: Kelley Jay
Published: August 2005

Canines of fossil hominoids and primitive catarrhines from several early, middle, and late Miocene sites were analyzed according to the shape indices described in Kelley (1995) and compared to those of males and females of extant great apes. In bivariate plots of the fossil canines utilizing the indices, 90% of the upper canines and 85% of the lower canines fell within or just outside the exclusively male or exclusively female territories delimited by the extant great apes. The remainder fell in the male‐female overlap zones. Sex assignments based on these distributions were nearly 100% concordant with classifications according to canine height, suggesting a high degree of accuracy. There were various taxon‐specific shifts in bivariate space among fossil genera, reflecting subtle differences in canine shape between taxa within the overall pattern of similarity to extant great apes as a whole. In many cases these shifts are matched by particular extant‐ape species and subspecies, while other fossil taxa have no exact analogue for canine shape among the extant great apes. However, the pattern of spatial segregation of canines identified as either male or female at each of the sites largely mirrors that of males and females within the extant‐ape sample, indicating that Miocene catarrhines shared with extant great apes a common pattern of shape differences between male and female canines, regardless of taxonspecific morphologies.

These observations demonstrate that the canines of fossil catarrhines can be sexed with a high degree of confidence based solely on intrinsic features of shape. This will permit more reliable characterizations of morphological sexual dimorphism among fossil species. It is also argued that canine shape is a more reliable indicator of sex in fossil taxa than are canine/molar size ratios. © 1995 Wiley‐Liss, Inc.
Cover Picture: Nanoparticle PCR: Nanogold‐Assisted PCR with Enhanced Specificity (Angew. Chem. Int. Ed. 32/2005)
Authors: Li Haikuo , Huang Jiehuan , Lv Junhong , An Hongjie , Zhang Xiaodong , Zhang Zhizhou , Fan Chunhai , Hu Jun
Published: August 2005

Favorable binding of gold nanoparticles to single‐stranded DNA decreases the likelihood of mispair formation during annealing and clearly increases the specificity and yield of PCR, one of the most important standard methods of molecular biology. In their Communication on pp. 5100 ff., Z. Zhang, C. Fan, J. Hu, and co‐workers report on this promising field of biotechnology. (Xiaobin Wang assisted in the production of this image.)
The status of host fish populations and fish species richness in European freshwater pearl mussel (Margaritifera margaritifera) streams
Authors: Geist Juergen , Porkka Markku , Kuehn Ralph
Published: August 2005

The status of host fish populations and fish species richness was investigated at 36 sites of 20 extant freshwater pearl mussel populations, including the drainages of the Elbe, Danube, Rhine, Weser, Aulne, Kemijoki and Tuuloma in Germany, the Czech Republic, France and Finland, by carrying out comparative electrofishings.

Brown trout (Salmo truttaf.fario) were found to be the available host fish for pearl mussels in all except one of the streams investigated with mean densities of 2861 ha−1(range 0–8710 ha−1) and a mean biomass of 119 kg ha−1(range 0–478 kg ha−1). Streams that had been frequently stocked with brown trout had higher trout biomass and densities of host fish than natural populations, but trout stocking had no positive effect in two of the streams investigated.

Fish species richness ranged from 2 to 16 species per stream and showed a negative correlation with host fish biomass and host fish densities. Undisturbed oligotrophic pearl mussel headwater streams usually only yielded a low number of fish species. Habitat degradation can reduce competitiveness of specialized trout and result in an increased abundance of ubiquitous or atypical species.

A link between the lack of juvenile pearl mussels and a lack of suitable host fish was only rarely observed. Functional pearl mussel populations with relatively high numbers of juveniles had significantly lower densities and biomass of host fish than pearl mussel populations without recent recruitment.

This study suggests that 0+ host fish are not necessarily required to sustain functional pearl mussel populations. Low densities of host fish can be compensated by the higher glochidia carrying capacity of older host fish with limited previous contact with pearl mussel glochidia, by the long reproductive period of mussels, and by low mortality rates of juvenile mussels during their post‐parasitic phase.

Copyright © 2005 John Wiley & Sons, Ltd.
Status of galaxiid fishes in Tasmania, Australia: conservation listings, threats and management issues
Authors: Hardie Scott A. , Jackson Jean E. , Barmuta Leon A. , White Robert W.G.
Published: August 2005

Fish of the family Galaxiidae are restricted to the southern hemisphere where they occupy a diverse array of habitats ranging from over 2000 m in elevation to sea level. Some species are diadromous and, hence, freshwater, estuarine and marine habitats are used during their life‐cycle; other species complete their entire life‐cycles in freshwater environments.

Tasmania has a diverse galaxiid fauna that accounts for 64% of native freshwater fish species found on the island. The Tasmanian galaxiid fauna is characterized by high species richness (5 genera and 16 species), endemism (11 species), restricted distributions, and non‐diadromous life histories (11 species).

The galaxiid fauna of Tasmania has significant conservation status with 69% of species considered ‘threatened’. The conservation status of the fauna is recognized at State, national and international levels.

The key threats to galaxiids in Tasmania are exotic species, hydrological manipulations, restricted distributions, general habitat degradation and exploitation of stocks.

Although work has recently been undertaken to conserve and manage Tasmanian galaxiid populations, the fauna is still thought to be imperilled. Knowledge gaps that need to be addressed include the biology and ecology of most species (e.g. reproductive biology, life histories, habitat use and requirements) and impacts of habitat manipulations, as well as mechanisms and impacts of interactions with exotic species. Techniques to monitor accurately the status of galaxiid species and their populations need to be developed and the coexistence of some galaxiids with introduced salmonids should also be examined.

Copyright © 2005 John Wiley & Sons, Ltd.
Narcissism, confidence, and risk attitude
Authors: Campbell W. Keith , Goodie Adam S. , Foster Joshua D.
Published: August 2005

The present research addresses whether narcissists are more overconfident than others and whether this overconfidence leads to deficits in decision making. In Study 1, narcissism predicted overconfidence. This was attributable to narcissists' greater confidence despite no greater accuracy. In Study 2, participants were offered fair bets on their answers. Narcissists lost significantly more points in this betting task than non‐narcissists, due both to their greater overconfidence and greater willingness to bet. Finally, in Study 3, narcissists' predictions of future performance were based on performance expectations rather than actual performance. This research extends the literature on betting on knowledge to the important personality dimension of narcissism. Copyright © 2004 John Wiley & Sons, Ltd.
Environmental considerations within manufacturing strategy: an international study
Authors: Crowe Déirdre , Brennan Louis
Published: August 2005

This paper examines the relative importance of environmental management in four key areas of manufacturing strategy: competitive priorities, action programmes, performance improvement and improvement goals. Its overall position in manufacturing strategy is measured through the creation of an original index using data from the 2001 International Manufacturing Strategy Survey (IMSS). Results show that in a minority of firms environmental management is positively positioned. The index's relationships with indicators of innovation and performance in manufacturing are examined. Some significant results include capabilities in the areas of strategy formalization, strategic fit and ISO14001 certification. While results are specific to the IMSS context, implications may be drawn for resource‐based view of the firm research on the application of resources and capabilities. An implication for policy makers is that the development of capabilities for strategy formalization and implementation should be incorporated into environmental policy. Copyright © 2005 John Wiley & Sons, Ltd and ERP Environment.
Tentative modelling of spray‐dry scrubbing of SO2
Authors: Karlsson Hans T. , Klingspor Jonas
Published: August 2005

A 0.5 MW spray‐dry scrubbing FGD pilot plant was used in the study of spray dryer performance over a wide range of operating conditions. Experimental findings were compared with a spray dryer model. During operation with large excesses of lime, the SO2 absorption was limited by gas phase diffusion. At operation with a shortage of lime, the rate limiting step was the dissolution rate of lime. In addition, the flow regime in a spray dryer can be best described as well mixed. The SO2 level in the flue gas was found to exert no direct effect on the efficiency of SO2 removal. The observed effects are attributed solely to the changes in the drying process, due to the inter‐dependence of slurry composition and SO2 concentration.
Calculation of reactive extraction in countercurrent columns
Authors: Bart Hans Jörg , Bauer Andreas , Marr Rolf
Published: August 2005

The kinetics of extraction processes with chemical reaction was studied experimentally on the system copper/Acorga PT 5050 and quantified according to meaningful kinetic models. These were coupled with other models describing the behaviour of dispersions in columns in order to permit a computer aided simultation of reactive extraction. Thus, a better prediction of column performance is achieved.
Density of desublimed layers
Authors: Wintermantel Klaus , Holzknecht Bernhard , Thoma Peter
Published: August 2005

Starting from the assumption that the growth of desublimed layers is governed mainly by heat and mass transfer, the authors present a model based on conditions in the diffusion boundary layer and suggest that the “hoarfrost”

Hereafter the term frost will be used instead of hoarfrost.

density depends on only one parameter. The discussion accounts for the process determining factors, i.e. the growth rate, mass transfer and gas concentration. The theoretical relationship is confirmed by the authors' own experiments on two systems and data from literature. The relationship can be established by a few laboratory experiments and permits the calculation of frost density and of associated variables, thus facilitating the optimization of desublimator design.
Homogeneous non‐equilibrium two‐phase critical flow model
Authors: Schröder Jens Jürgen , Vuxuan Nha
Published: August 2005

An important aspect of nuclear and chemical reactor safety is the ability to predict the maximum or critical mass flow rate from a break or leak in a pipe system. At the beginning of such a blowdown, if the stagnation condition of the fluid is subcooled or slightly saturated thermodynamic non‐equilibrium exists in the downstream, e.g. the fluid becomes superheated to a degree determined by the liquid pressure. A simplified non‐equilibrium model, explained in this report, is valid for rapidly decreasing pressure along the flow path. It presumes that fluid has to be superheated by an amount governed by physical principles before it starts to flash into steam. The flow is assumed to be homogeneous, i.e. the steam and liquid velocities are equal. An adiabatic flow calculation mode (Fanno lines) is employed to evaluate the critical flow rate for long pipes. The model is found to satisfactorily describe critical flow tests. Good agreement is obtained with the large scale Marviken tests as well as with small scale experiments.
Axial pressure profile in circulating fluidized beds
Authors: Wirth Karl‐Ernst
Published: August 2005

Design and operation of a circulating fluidized bed requires the knowledge of fluid mechanics. According to heat and mass transfer as well as chemical reactions, the effect of the set superficial gas velocity on the axial pressure profile is of particular interest. The axial pressure profile was measured for a variety of solids, as a function of the superficial gas velocity, in a cylindrical circulating fluidized bed with an inner diameter of 0.19 m and an overall height of 11.5 m. Depending on the solids content and superficial gas velocity, two or one sections can be observed in the plant where the pressure gradient is constant. A pressure profile with one pressure gradient exists only at high gas velocities, so long as the acceleration pressure drop immediately above the gas distributor is negligible. Comparison of measured pressure drops in circulating fluidized beds with those measured in vertical pneumatic conveying led to a state diagram for vertical gas‐solid flows. The operation behaviour of different types of circulating fluidized bed plants can be explained with the aid of this diagram.
Effect of chlorine on the selectivity of a fischer‐tropsch catalyst composed of iron/vanadium oxides
Authors: Jacobs Jochen , Baerns Manfred
Published: August 2005

Fischer‐Tropsch catalysts (Fe/V oxides with ZnO and K2CO3 as promoters) were exposed to CHCl3, thereby producing surface and bulk chlorides. The effect of this exposure on activity and selectivity was studied in a continuous recycle reactor at a total pressure of 10 bar (CO/H2 in most experiments: ca 1:1) in a temperature range between 200 and 343°C. CHCl3 was introduced in amounts of up to 1 × 10−2 mol chlorine per g catalyst. The catalyst samples were characterized by internal surface area, pore‐size distribution and adsorption capacities for CO, H2 and C2H4. Prior to synthesis, the catalysts were reduced by H2. Catalyst exposure to CHCl3 resulted in a decrease of activity and considerable changes in product distribution. Hydrogenation and isomerization of 1‐olefins were partly suppressed; the chain length of the products was slightly increased. Deactivation of the catalysts due to chlorine addition was partly reversible during operation, while olefin formation was not significantly altered with time‐on‐stream. The effect of chlorine on activity and selectivity is explained by dissociation of CO as the chain initiating step and CO insertion into a carbon/metal bond as a possible chain propagation step. Since adsorption capacity for H2 decreases on the addition of chlorine, this may also contribute to lower activity and change in selectivity, compared to the unexposed catalyst.
Derivation, selection, evaluation and use of asymptotes
Authors: Churchill Stuart W.
Published: August 2005

Asymptotes are known to be useful, but their potential in interpreting and correlating chemical and physical behaviour is seldom exploited fully. The derivation and selection of asymptotes for particular as well as limiting cases is described. The evaluation of the range of validity and applicability, if any, of asymptotes is also considered. Asymptotes are shown to be uniquely useful in the identification of groupings of variables which minimize parameteric variations, as upper and lower bounds, as trial functions in the method of weighted residuals, and most especially as components of correlating equations.
Relationship between residence time, fluid dynamics and efficiency in countercurrent flow equipment
Authors: Billet Reinhard
Published: August 2005

The suitability of any item of equipment for a given thermal separation process cannot always be judged solely in the light of efficient and loading range data. In vacuum rectification, involving a large number of theoretical stages, the vapour pressure drop per transfer unit exerts a considerable effect on the energy consumption and thus largely governs the choice of column fittings. Furthermore, the pressure drop per transfer unit determines the temperature at the bottom of a rectification column and, hence, the suitability of the equipment for the separation of heat‐sensitive products. It is also an important criterion for compressor requirements in absorption processes. Another factor of considerable importance in separating heat‐sensitive mixtures by distillation is the time during which the product, particularly the liquid phase, is exposed to a given temperature in the column. Therefore, a standardized liquid residence time has been adopted to evaluate the systems in their entirely. This residence time depends on the hydrodynamic conditions in the column and is thus closely related to pressure drop and efficiency. Further important factors, which may decide the selection of column internals, are the specific volume and mass of the column. Based on theoretical considerations, a flow model is derived for describing the main loading range of countercurrent packed columns; the relationships between the above mentioned parameters are presented.
Absorption of SO2 by aqueous NaOH solutions in the presence of a surfactant
Authors: Vázquez Gonzalo , Antorrena Gervasio , Chenlo Francisco , Paleo Francisco
Published: August 2005

A report is presented on the influence of liquid flow rate, NaOH concentration, column length and presence of 5 × 10‐3 wt‐% of the surfactant SLS on the rate of absorption of pure SO2 by aqueous NaOH solution in a sphere‐and‐cylinder column. The presence of sodium lauryl sulphate (SLS) prevented axial turbulence which increased mass transfer in longer columns and was almost independent of the flow rate. The enhancement factor due to the reaction between SO2 and NaOH with respect to the process of physical absorption was analyzed for the systems with excess OH‐ in the outflow. The results obtained in the presence of a surfactant are satisfactorily explained by film theory with a single reaction plane model. Those obtained in the absence of surfactant are best described by a two‐plane model using renewal theory.
A new fluid dynamic model for mixing of newtonian and power‐law liquids in the transient regime
Authors: Zeppenfeld Rolf , Mersmann Alfons B.
Published: August 2005

In the description of mixing processes influenced by viscosity in pseudoplastic (power‐law) fluids, a definition of representative viscosity is normally used which takes into account the variable flow behaviour of the stirred material as a result of different shear stresses. In this context, the Metzner and Otto concept, which postulates that a representative shear rate is proportional to stirring speed, has become widely know, although the power calculation is inaccurate, particularly in the transient regime between the laminar and turbulent flow. A new model of fluid dynamics in the mixing vessel is presented, based on the increase of the mean flow velocity standardized with the stirrer's tip velocity in the transition regime. It provides a physical explanation for the above deviations. A suitable definition of representative viscosity substantially improves the accuracy of calculations of the stirring power in power‐law fluids.
Organosolv delignification of southern pine – an alternative pulping process
Authors: Zargarian K. , Aravamuthan R. , April G. C.
Published: August 2005

Aqueous ethylenediamine‐ethanol‐anthraquinone (EDA‐EtOH‐AQ) pulping of Southern Yellow Pine was studied for lignin removal and pulp yield. Temperature, time and ethylenediamine concentration in the solvent solution were studied and equations for lignin content and lignin‐free yield were developed. Lignin content is decreased by an increase of temperature, time or EDA concentration. Lignin‐free yield of pulp decreased with an increase in temperature or time, but increased with increasing EDA concentration. Overall, the solvent is selective, that is, large quantities of lignin are removed while the retention of cellulose remains high.
Consistent scale‐up procedure for the power consumption in agitated non‐newtonian fluids
Authors: Böhme Gert , Stenger Matthias
Published: August 2005

It is shown how a consistent scale‐up rule for the power consumption in agitated non‐Newtonian liquids can be obtained. The new approach is based on the concept of including the real liquid in a set of liquids with similar rheological properties and of using, in a small scale laboratory system, a suitable member of that set instead of the original liquid. Considerations of similarity lead to simple unique selection rules for the actual test liquid and for the stirrer speed in the laboratory experiment as well as to a prediction of the power requirement in the real system. The theory is tested experimentally by means of different aqueous polyacrylamide solutions. The results are compared with predictions, according to Metzner and Otto as well as Rieger and Novák.
Bubble column research in Japan
Authors: Yoshida Fumitake
Published: August 2005

Many experimental studies on the bubble column have been reported by Japanese researchers since around 1960. They include studies of bubble behaviour, bubble size distribution, transition from the homogeneous bubbly flow regime to the heterogeneous liquid circulation regime, liquid velocity distribution, longitudinal liquid mixing, hydrodynamic modelling, the gas holdup, and the volumetric coefficient of gas‐liquid mass tranfer kLa. Studies covered various modified bubble columns, such as the airlift reactor with an external or internal loop, the packed bubble column, and others. Performance of three‐phase bubble columns, which deal with suspensions or emulsions, and their use as bioreactors or chemical reactors were also studied.
Application of modern packings in thermal separation processes
Authors: Billet Reinhard , Maćkowiak Jerzy
Published: August 2005

A report is presented on the performance of modern dumped and structured packings for application in the field of thermal separation processes. The evaluation of the results is based on extensive experimental investigations of rectification, absorption, and desorption systems. The following are indicated: the efficiency in terms of the number of theoretical stages per unit height or in terms of the height of transfer unit or volumetric mass transfer coefficient, the pressure drop per unit height as well as per theoretical stage or per gas phase transfer unit, and the liquid hold‐up, whereby either the gas capacity factor or the liquid load was adopted as influencing parameter, and finally the maximum gas capacity factor as a function of the flow parameter. The results are presented in diagrams and tables.
Thermal radiation of gas/solid mixtures
Authors: Elsner Thomas , Köneke Dieter , Weinspach Paul‐Michael
Published: August 2005

Thermal radiation of gas/solid mixtures in high‐temperature heat exchangers is of considerable importance for the design of heat exchange surfaces. Therefore, an experimental plant was constructed to measure solid particle emissivities, since there is a lack of relevant data in the existing literature. A theoretical equation was derived to describe the solid particle emissivity as a function of layer thickness, specific solid surface area, solid loading and absorption and scatter coefficients. Measurements were carried out for fluidized bed ash and quartz sand. The emissivities of these particle fractions increase with increasing layer thickness, slid loading, specific solid surface area and temperature. The description of these data by the derived model equation is very satisfactory. No dependence on wavelength was observed. The ash components do exert some influence which, for the present, cannot be described exactly.
Scale‐up of mechanically agitated extraction columns
Authors: Pilhofer Theo
Published: August 2005

The deterioration of mass transfer efficiency of an extraction column with increasing column diameter is the result of developing residence time distributions. These effects can be described by one‐dimensional dispersion model. However, it must be verified whether the requirements for its application are fulfilled in the different types of agitated extraction columns. For the columns for which the dispersion model can be applied, a relationship will be derived between the necessary increase of column height with column diameter. This is based on the equations for calculation of the dispersion coefficient of the continuous phase. If the dispersion model cannot be applied to given a type of column, an investigation will be made on the possible modifications of operation or changes in construction, in order to permit a scale‐up procedures as proposed here.
Subcooled boiling heat transfer to R 12 in an annular vertical channel
Authors: Bräuer Holger , Mayinger Franz
Published: August 2005

Detailed knowledge of the physical phenomena involved in subcooled boiling is of great importance for the design of liquid‐cooled heat generating systems with high heat fluxes. Experimental heat transfer data were obtained for forced convective boiling of dichloro‐difluoroethane (R 12). The flow is circulated upwards through a concentric annular vertical channel. The inner and outer diameters of the annulus are 0.016 m and 0.03 m respectively. The reduced pressures studied were 0.24 ≤ p/pcrit ≤ 0.8, inlet subcooling varied from 10 to 75 K and mass fluxes from 500 to 3000 kg/m2s, which corresponds to Re numbers from 30000 to 300000. The experiments, described in this study, demonstrate that liquid fluorocarbons show certain unusual boiling characteristics in the subcooled flow, such as hysteresis of the boiling curve. These characteristics are attributed to the properties of the fluid, mainly the Pr number and the very low surface tension. The pronounced boiling curve hysteresis can be explained by the fact that large nucleation sites may have been flooded prior to incipient boiling. A dimensionless regression formula is presented which predicts the onset of subcooled boiling as a function of reduced pressure (p/pcrit), Boiling‐(Bo), Reynolds‐(Re), and a modified Jacob number (Ja), over the whole range of parameters studied, with a good accuracy, including water data from literature.
The importance of corrosion prevention for the safety of chemical plants
Authors: Gräfen Hubert
Published: August 2005

One of the most important tasks to eliminate dangers in chemical plants is the prevention of corrosion. This implies the provision of safe enclosures and reaction spaces for the substances to be processed. The present contribution deals with the procedure in the selection of materials for equipment exposed to corrosion and stresses the difficulties connected with the elimination of local corrosion. The relevance of prevention of crack forming corrosion processes is emphasized. Problems to be solved in order to obtain results from investigations, suitable for a safe application of a materials under practical conditions, are indicated.
Evaporation and pervaporation of a binary mixture from an inert carrier liquid
Authors: Riede Thomas , Schlünder Ernst Ulrich
Published: August 2005

Bench‐Scale experiments were carried out with the ternary mixture 2‐propanol/water/glycerol. In a cylindrical vessel, the stirred and thermostated liquid was exposed to a preheated and either dry or humidified air stream. The mixture was evaporated either from a free surface or from the surface of a porous plate. On evaporating the mixture from a porous plate into a dry air stream, the less volatile component water escapes preferentially; in the case of evaporation from a free surface, water is retained in the mixture. In the former case, selectivity is liquid diffusion controlled, in the latter, the gas‐side mass transfer and the thermodynamic equilibrium are the controlling mechanisms. On reducing the gas flow rate, the more volatile alcohol evaporates preferentially in both cases; the selectivity is controlled only by thermodynamic equilibrium. Humidification of the air stream with water vapour causes preferential evaporation of the alcohol at an increased rate. Furthermore, instabilities in the liquid boundary layer due to density gradients and surface tension effects may affect the selectivity of evaporation. Experimental results show that the selectivity of evaporation can be manipulated by choosing appropriate evaporation conditions. The theory, which applies the generalized Stefan‐Maxwell equations to diffusion in the liquid, can describe these effects.
A new regenerable process for the recovery of SO2
Authors: Erga Olav
Published: August 2005

Increasing demand for regenerable processes with SO2 recovery is to be expected. Advantages and limitations of the earlier developed citrate and adipate absorption/ steam stripping process are compared with those of the Wellman‐Lord (sulphite) process. On the basis of comprehensive laboratory studies, a new process is proposed which supplements the citrate and adipate process. In this new process, the absorbent is a concentrated sodium phosphate buffer and the loaded buffer is regenerated by evaporation. The main buffer component is Na2HPO4, but NaH2PO4 is added in order to obtain a more complete stripping of SO2 during regeneration. The new process promises excellent absorption properties for SO2 with extremely low oxidation losses, regeneration with few incrustation problems and appreciable energy savings.
A new appraisal of mass transfer processes in zeolites by transient methods
Authors: Authelin Jean‐René , Schweich Daniel , Villermaux Jacques
Published: August 2005

Transient diffusion of inert gases into Zeolon 900 H, a zeolite of the mordenite type, was studied by the chromatographic method. Experiments were performed with argon and helium either as tracer or as carrier gas. The diffusion of argon was also studied in a carrier gas containing methanol at a low temperature (75°C, no reaction) and at higher temperatures (up to 130°C) when some dehydration of methanol to dimethyl ether takes place. The adsorption isotherm of argon is linear. In the absence of methanol, its penetration into microcrystals of zeolite is equally well represented either by an effective diffusion coefficient D′μ = 7.4 × 10−8exp(−2873/T)m2s−1 or by a mass transfer coefficient at the crystallite surface keμ = 1.9 × 10−4 exp(−1324/T) ms−1. A small amount of methanol in the carrier gas considerably slows down the transfer of argon (by a factor of 40 for D′μ and 550 for keμ) showing the “blocking” effect of adsorbed methanol. In addition, transient adsorption can no longer be accounted for by a single transfer time. The size distribution of microcrystals, determined from Scanning Electron Microscope photographs leads to a Transfer Time Distribution which account well for experimental breakthrough curves without any parameter fitting. This interpretation is supported by experiments under reaction conditions where transport of argon within crystallites increases faster with temperature than in the absence of reaction due to the transformation of methanol into dimethyl ether, which is less adsorbed and thus provides lesser hindrance to argon diffusion.
Coupled simulation of heat transfer and reaction in a steam reforming furnace
Authors: Plehiers Patrick M. , Froment Gilbert F.
Published: August 2005

For design and simulation of chemical process furnaces in accordance with present‐day standards, the temperature distributions in the firebox and in the reactors must be generated simultaneously. This calls for coupling of the simulations of the firebox and of the reactor. For the calculation of heat transfer in the firebox, a generalized furnace simulations program, based on the zone method, is applied. Monte Carlo simulation techniques are used to determine the view factors. The location of the burners is explicitly accounted for. Absorption and emission of radiation by the flue gas are calculated by considering band contributions for carbon dioxide and water. For the simulation of the steam reforming reactors, a one‐dimensional heterogeneous model, which accounts for the presence of intraparticle partial pressure gradients, is used. The simulated temperature distribution in the furnace is in excellent agreement with industrial results, as is the simulated product distribution.