bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Type V Staphylococcal Cassette Chromosome
mec
Driven by a Novel Cassette Chromosome Recombinase,
ccrC
Authors: Ito Teruyo , Ma Xiao Xue , Takeuchi Fumihiko , Okuma Keiko , Yuzawa Harumi , Hiramatsu Keiichi
Published: June 2004

Staphylococcal cassette chromosome
mec
(SCC
mec
) is a mobile genetic element composed of the
mec
gene complex, which encodes methicillin resistance, and the
ccr
gene complex, which encodes the recombinases responsible for its mobility. The
mec
gene complex has been classified into four classes, and the
ccr
gene complex has been classified into three allotypes. Different combinations of
mec
gene complex classes and
ccr
gene complex types have so far defined four types of SCC
mec
elements. Now we introduce the fifth allotype of SCC
mec
, which was found on the chromosome of a community-acquired methicillin-resistant
Staphylococcus aureus
strain (strain WIS [WBG8318]) isolated in Australia. The element shared the same chromosomal integration site with the four extant types of SCC
mec
and the characteristic nucleotide sequences at the chromosome-SCC
mec
junction regions. The novel SCC
mec
carried
mecA
bracketed by IS
431
(IS
431
-
mecA
-Δ
mecR1-
IS
431
), which is designated the class C2
mec
gene complex; and instead of
ccrA
and
ccrB
genes, it carried a single copy of a gene homologue that encoded cassette chromosome recombinase. Since the open reading frame (ORF) was found to encode an enzyme which catalyzes the precise excision as well as site- and orientation-specific integration of the element, we designated the ORF cassette chromosome recombinase C (
ccrC
), and we designated the element type V SCC
mec
. Type V SCC
mec
is a small SCC
mec
element (28 kb) and does not carry any antibiotic resistance genes besides
mecA
. Unlike the extant SCC
mec
types, it carries a set of foreign genes encoding a restriction-modification system that might play a role in the stabilization of the element on the chromosome.
Inhibitor-Sensitive AmpC β-Lactamase Variant Produced by an
Escherichia coli
Clinical Isolate Resistant to Oxyiminocephalosporins and Cephamycins
Authors: Doi Yohei , Wachino Jun-ichi , Ishiguro Masaji , Kurokawa Hiroshi , Yamane Kunikazu , Shibata Naohiro , Shibayama Keigo , Yokoyama Keiko , Kato Haru , Yagi Tetsuya , Arakawa Yoshichika
Published: June 2004

Escherichia coli
HKY28, a ceftazidime-resistant strain isolated from a urine specimen in Japan, produced an inhibitor-sensitive AmpC β-lactamase variant. The deduced amino acid sequence of the enzyme contained a number of substitutions and a tripeptide deletion (Gly286-Ser287-Asp288) compared with the sequence of native AmpC of
E. coli
. When the deletion was reverted by a 9-base insertion at the relevant site of
ampC
in the clone, the typical inhibitor-resistant phenotype of AmpC was restored, while at the same time the levels of resistance to ceftazidime, cefpirome, and cefepime were reduced eightfold or more. Molecular modeling studies indicated that a structural change took place in the H-10 helix as a result of the deletion, and this change caused an alteration of the substrate binding site, leading to a unique phenotype analogous to that of inhibitor-sensitive class A extended-spectrum β-lactamases. The degree of inhibition was greater with sulbactam and tazobactam than with clavulanic acid. To our knowledge, this is the first report to have characterized an
E. coli ampC
that encodes chromosomal AmpC β-lactamase sensitive to the available β-lactamase inhibitors.
Oxygen Limitation Contributes to Antibiotic Tolerance of
Pseudomonas aeruginosa
in Biofilms
Authors: Borriello Giorgia , Werner Erin , Roe Frank , Kim Aana M. , Ehrlich Garth D. , Stewart Philip S.
Published: June 2004

The role of oxygen limitation in protecting
Pseudomonas aeruginosa
strains growing in biofilms from killing by antibiotics was investigated in vitro. Bacteria in mature (48-h-old) colony biofilms were poorly killed when they were exposed to tobramycin, ciprofloxacin, carbenicillin, ceftazidime, chloramphenicol, or tetracycline for 12 h. It was shown with oxygen microelectrodes that these biofilms contain large anoxic regions. Oxygen penetrated about 50 μm into the biofilms, which averaged 210 μm thick. The region of active protein synthesis was visualized by using an inducible green fluorescent protein. This zone was also limited to a narrow band , approximately 30 μm wide, adjacent to the air interface of the biofilm. The bacteria in mature biofilms exhibited a specific growth rate of only 0.02 h
−1
. These results show that 48-h-old colony biofilms are physiologically heterogeneous and that most of the cells in the biofilm occupy an oxygen-limited, stationary-phase state. In contrast, bacteria in 4-h-old colony biofilms were still growing, active, and susceptible to antibiotics when they were challenged in air. When 4-h-old colony biofilms were challenged under anaerobic conditions, the level of killing by antibiotics was reduced compared to that for the controls grown aerobically. Oxygen limitation could explain 70% or more of the protection afforded to 48-h-old colony biofilms for all antibiotics tested. Nitrate amendment stimulated the growth of untreated control
P. aeruginosa
isolates grown under anaerobic conditions but decreased the susceptibilities of the organisms to antibiotics. Local oxygen limitation and the presence of nitrate may contribute to the reduced susceptibilities of
P. aeruginosa
biofilms causing infections in vivo.
Active Efflux of Ciprofloxacin from J774 Macrophages through an MRP-Like Transporter
Authors: Michot Jean-Michel , Van Bambeke Françoise , Mingeot-Leclercq Marie-Paule , Tulkens Paul M.
Published: June 2004

The accumulation and efflux kinetics of ciprofloxacin have been examined by using murine J774 macrophages. Accumulation (at equilibrium) was increased (three- to fourfold) (i) when cells were incubated with high extracellular drug concentrations (typically 200 mg/liter) as opposed to clinically meaningful concentrations (10 mg/liter or lower), (ii) during ATP- depletion and at acid pH, and (iii) during coincubation with probenecid, gemfibrozil and the preferential multidrug resistance-related protein (MRP) inhibitor MK571. All these conditions were also associated with a marked decrease in ciprofloxacin efflux (half-lives increased from <2 min in controls to up to 10 min). Monensin (a proton ionophore), verapamil, and the preferential P-glycoprotein (P-gp) inhibitor GF120918 had no or only minimal effect, while cyclosporin A, which is not specific for P-gp but also acts on MRP, had an intermediate effect. Short-term uptake studies showed that the influence of the modulators on the apparent drug influx was almost immediate (delay of ≤1 min). Cells made resistant to probenecid and showing a marked overexpression of MRP1 (by Western blot analysis and confocal microscopy) accumulated ciprofloxacin to almost the same extent as did control cells, but efflux was inhibited less by probenecid, gemfibrozil, and MK571. We conclude that ciprofloxacin is subject to constitutive efflux in J774 macrophages through the activity of an MRP-related transporter which is probably distinct from MRP1. We also suggest that the cellular accumulation of ciprofloxacin in wild-type cells is constitutively impaired at therapeutically meaningful concentrations.
Purification and Characterization of Recombinant
Staphylococcus haemolyticus
DNA Gyrase and Topoisomerase IV Expressed in
Escherichia coli
Authors: Bronstein Joel C. , Olson Stacey L. , LeVier Kristin , Tomilo Mark , Weber Peter C.
Published: June 2004

The subunits of DNA gyrase and topoisomerase IV from
Staphylococcus haemolyticus
were expressed in
Escherichia coli
, purified to homogeneity, and used to reconstitute active enzymes that were sensitive to known topoisomerase inhibitors. This represents the first description of a method for isolating type II topoisomerases of a coagulase-negative staphylococcal species.
FACTOR MAPS OF LAMBDA-GRAPH SYSTEMS AND INCLUSIONS OF C*-ALGEBRAS
Authors: MATSUMOTO KENGO
Published: June 2004

A λ-graph system is a labeled Bratteli diagram with shift transformation. It is a generalization of finite labeled graphs and presents a subshift. In [Doc. Math. 7 (2002), 1–30], the author introduced a C*-algebra [Formula: see text] associated with a λ-graph system [Formula: see text] as a generalization of the Cuntz–Krieger algebras. In this paper, we study a functorial property between factor maps of λ-graph systems and inclusions of the associated C*-algebras with gauge actions. We prove that if there exists a surjective left-covering λ-graph system homomorphism [Formula: see text], there exists a unital embedding of the C*-algebra [Formula: see text] into the C*-algebra [Formula: see text] compatible to its gauge actions. We also show that a sequence of left-covering graph homomorphisms of finite labeled graphs gives rise to a λ-graph system such that the associated C*-algebra is an inductive limit of the Cuntz–Krieger algebras for the finite labeled graphs.
Neuronal Activation in the Medulla Oblongata During Selective Elicitation of the Laryngeal Adductor Response
Authors: Ambalavanar Ranjinidevi , Tanaka Yasumasa , Selbie W. Scott , Ludlow Christy L.
Published: June 2004

Swallow and cough are complex motor patterns elicited by rapid and intense electrical stimulation of the internal branch of the superior laryngeal nerve (ISLN). The laryngeal adductor response (LAR) includes only a laryngeal response, is elicited by single stimuli to the ISLN, and is thought to represent the brain stem pathway involved in laryngospasm. To identify which regions in the medulla are activated during elicitation of the LAR alone, single electrical stimuli were presented once every 2 s to the ISLN. Two groups of five cats each were studied; an experimental group with unilateral ISLN stimulation at 0.5 Hz and a surgical control group. Three additional cats were studied to evaluate whether other oral, pharyngeal, or respiratory muscles were activated during ISLN stimulation eliciting LAR. We quantified ≤22 sections for each of 14 structures in the medulla to determine if regions had increased Fos-like immunoreactive neurons in the experimental group. Significant increases ( P < 0.0033) occurred with unilateral ISLN stimulation in the interstitial subnucleus, the ventrolateral subnucleus, the commissural subnucleus of the nucleus tractus solitarius, the lateral tegmental field of the reticular formation, the area postrema, and the nucleus ambiguus. Neither the dorsal motor nucleus of the vagus, usually active for swallow, nor the nucleus retroambiguus, retrofacial nucleus, and the lateral reticular nucleus, usually active for cough, were active with elicitation of the laryngeal adductor response alone. The results demonstrate that the laryngeal adductor pathway is contained within the broader pathways for cough and swallow in the medulla.
shockedGene Is Required for the Function of a Premotor Network in the Zebrafish CNS
Authors: Cui Wilson W. , Saint-Amant Louis , Kuwada John Y.
Published: June 2004

The analysis of behavioral mutations in zebrafish can be a powerful strategy for identifying genes that regulate the function and development of neural circuits in the vertebrate CNS. A neurophysiological analysis of the shocked ( sho) mutation that affects the initiation of swimming after mechanosensory stimulation was undertaken to identify the function of the sho gene product in the developing motor circuitry. The cutaneous Rohon-Beard (RB) mechanosensory neurons responded normally to stimulation, and muscle fibers were unaffected in sho embryos, suggesting that the output of the CNS is abnormal. Indeed whole cell patch recordings from mutant muscle cells showed normal spontaneous miniature endplate potentials, but abnormal touch-evoked endplate potentials. Furthermore, motor neuron recordings showed that bursts of rhythmic action potentials from synaptically dependent depolarizations are initiated in wild-type motor neurons after sensory stimulation or bath application of N-methyl-d-aspartate. These bursts presumably correspond to bouts of swimming. In sho motor neurons, the touch-evoked depolarizations were not sustained, resulting in an abbreviated burst of action potentials. The defective responses were not due to any obvious defect in sho motor neurons because their basic properties were normal. These results suggest that in sho embryos, there is aberrant motor processing within the CNS and that normal motor processing requires the sho gene product.
Function and survival of dendritic cells depend on endothelin-1 and endothelin receptor autocrine loops
Authors: Guruli Georgi , Pflug Beth R. , Pecher Stefana , Makarenkova Valeria , Shurin Michael R. , Nelson Joel B.
Published: June 2004

The biologic effects of endothelin-1 (ET-1) are not limited to its potent vasoconstricting activity. The endothelin receptors, ETA and ETB, have differential tissue and functional distributions. Here we showed that dendritic cells (DCs), the major antigen-presenting cells in the adaptive limb of the immune system, produce large amounts of ET-1 and significantly increase the expression of endothelin receptors upon maturation. Selective blockade of the ETA receptor significantly reduced expression of the mature DC marker CD83, decreased the production of the immunostimulatory cytokine interleukin-12, down-regulated DC ability to stimulate T cells, and promoted DC apoptosis. Selective ETB receptor blockade, on the other hand, resulted in increased expression of CD83 and improved DC survival. Therefore, ET-1/ETA/ETB autocrine/paracrine loops on DCs appear to be essential for the normal maturation and function of human DCs, presenting a unique target for immunomodulatory therapies. (Blood. 2004;104:2107-2115)
A new anti-idiotype antibody capable of binding rituximab on the surface of lymphoma cells
Authors: Cragg Mark S. , Bayne Mike B. , Tutt Alison L. , French Ruth R. , Beers Stephen , Glennie Martin J. , Illidge Timothy M.
Published: June 2004

The chimeric anti-CD20 monoclonal antibody (mAb), rituximab, is an established part of the management of many non-Hodgkin lymphomas. The in vivo action of rituximab remains elusive, and this partially reflects a lack of highly specific reagents to detect rituximab binding at the cell surface. Here we report a new high-affinity mAb (MB2A4) with fine specificity for the idiotype of rituximab. It is able to detect rituximab in vitro, in the presence of high levels of human immunoglobulin G (IgG), in the serum of patients receiving rituximab therapy, and, surprisingly, when rituximab is bound to CD20 on the cell surface. We propose that the anti–idiotype (Id) binds to rituximab molecules bound univalently at the cell surface, facilitated by the relatively high off-rate of rituximab. This reagent provides new insights into the binding of rituximab at the cell surface and demonstrates a mode of binding that could be exploited for the surface detection of other mAbs with clinical and biologic applications.
High-Frequency Stimulation Induces Ethanol-Sensitive Long-Term Potentiation at Glutamatergic Synapses in the Dorsolateral Bed Nucleus of the Stria Terminalis
Authors: Weitlauf Carl , Egli Regula E. , Grueter Brad A. , Winder Danny G.
Published: June 2004

Anatomical and functional data support a critical role for the bed nucleus of the stria terminalis (BNST) in the interaction between stress and alcohol/substance abuse. We report here that neurons of the dorsal anterolateral BNST respond to glutamatergic synaptic input in a synchronized way, such that an interpretable extracellular synaptic field potential can be readily measured. High-frequency stimulation of these glutamatergic inputs evoked NMDA receptor (NMDAR)-dependent long-term potentiation (LTP). We found that an early portion of this LTP is reduced by acute exposure to ethanol in a GABAAreceptor-dependent manner. This effect of ethanol is accompanied by a significant and reversible dose-dependent attenuation of isolated NMDAR signaling and is mimicked by incomplete NMDAR blockade.
Primitive Roles for Inhibitory Interneurons in Developing Frog Spinal Cord
Authors: Li W.-C. , Higashijima Shin-ichi , Parry D. M. , Roberts Alan , Soffe S. R.
Published: June 2004

Understanding the neuronal networks in the mammal spinal cord is hampered by the diversity of neurons and their connections. The simpler networks in developing lower vertebrates may offer insights into basic organization. To investigate the function of spinal inhibitory interneurons inXenopustadpoles, paired whole-cell recordings were used. We show directly that one class of interneuron, with distinctive anatomy, produces glycinergic, negative feedback inhibition that can limit firing in motoneurons and interneurons of the central pattern generator during swimming. These same neurons also produce inhibitory gating of sensory pathways during swimming. This discovery raises the possibility that some classes of interneuron, with distinct functions later in development, may differentiate from an earlier class in which these functions are shared. Preliminary evidence suggests that these inhibitory interneurons express the transcription factor engrailed, supporting a probable homology with interneurons in developing zebrafish that also express engrailed and have very similar anatomy and functions.
Engrailed-1 Expression Marks a Primitive Class of Inhibitory Spinal Interneuron
Authors: Higashijima Shin-ichi , Masino Mark A. , Mandel Gail , Fetcho Joseph R.
Published: June 2004

Studies in chicks and mice have suggested that transcription factors mark functional subtypes of interneurons in the developing spinal cord. We used genetic, morphological, and physiological studies to test this proposed association in zebrafish. We found that Engrailed-1 expression uniquely marks a class of ascending interneurons, called circumferential ascending (CiA) interneurons, with ipsilateral axonal projections in both motor and sensory regions of spinal cord. These cells express the glycine transporter 2 gene and are the only known ipsilateral interneurons positive for this marker of inhibitory transmission. Patch recordings show that the CiA neurons are rhythmically active during swimming. Pairwise recordings from the CiA interneurons and postsynaptic cells reveal that the Engrailed-1 neurons produce monosynaptic, strychnine-sensitive inhibition of dorsal sensory interneurons and also inhibit more ventral neurons, including motoneurons and descending interneurons. We conclude that Engrailed-1 expression marks a class of inhibitory interneuron that seems to provide all of the ipsilateral glycinergic inhibition in the spinal cord of embryonic and larval fish. Individual Engrailed-1-positive cells are multifunctional, playing roles in both sensory gating and motor pattern generation. This primitive cell type may have given rise to several, more specialized glycinergic inhibitory interneurons in birds and mammals. Our data support the view that the subdivision of spinal cord into different regions by transcription factors defines a primitive functional organization of spinal interneurons that formed a developmental and evolutionary foundation on which more complex systems were built.
Agentensysteme für die Logistik im Schienenverkehr (Multi Agent Systems for Logistics in Rail Transport)
Authors: Braun Imma , König Stefan , Schnieder Eckehard
Published: June 2004

Der makrologistische Strukturwandel des Güterverkehrsmarkts, hervorgerufen durch Substitutions-, Güterstruktur-, Logistik- und Integrationseffekte, führt infolge veränderter Anforderungen an die Strukturen und Prozesse des Güterverkehrs zu zunehmenden Verlusten an Marktanteilen des Schienengüterverkehrs am Gesamtgüterverkehrsmarkt. Ursache hierfür ist eine mangelnde Übereinstimmung von gewandelten Kundenanforderungen mit dem Leistungsangebot des Schienenverkehrs. Der Beitrag stellt ein neues Logistikkonzept für den Bahnbereich vor, das die Flexibilität im Schienengüterverkehr durch die Verschränkung von Organisations- und Betriebsprozessen erhöht. In Kombination mit dem Einsatz kleiner, autonomer Transporteinheiten trägt es dazu bei, den veränderten Marktanforderungen an den Güterverkehr gerecht zu werden.
Phase equilibria in systems with ethylene above its critical temperature
Authors: Todd David B. , Elgin Joseph C.
Published: June 2004

A study was made of the mutual solubility of ethylene with various polar and nonpolar relatively high‐molecular‐weight organic compounds at temperatures 1° and 10° C. respectively above the critical temperature of ethylene and at pressures up to 1,500 Ib./sq.in.abs. For many compounds Henry's law was found to be applicable for the liquid phase up to approximately two thirds of the critical pressure of ethylene. In the critical region the solubility of ethylene was extremely sensitive to small changes in both temperature and pressure. The various types of phase behavior encountered were classified according to the nonideality involved. The results of this investigation indicate that a gas near its critical conditions is often capable of dissolving relatively nonvolatile materials in sufficient concentrations to warrant consideration of a separation process using such a gas as the extracting medium, namely fluid‐liquid extraction.
The fall of single liquid drops through water
Authors: Hu Shegen , Kinter R. C.
Published: June 2004

The steady motion of single drops of ten organic liquids falling through a stationary water field is discussed. A correlation is presented for nine systems with the exception of the aniline‐water system, in the form of a single curve relating the drag coefficient, Weber number, Reynolds number, and a physical property group. The curve can be used directly to predict the terminal velocity, drag coefficient, Reynolds number, and Weber number for any given equivalent drop size.

A break point in the curve serves to predict the peak velocity and its related quantities. The critical drop size is predicted from the pertinent physical properties alone. All these estimations were accurate within 10% for the systems used. The interfacial tensions ranged from 24 to 45 dynes/cm. and the drop densities from 1.100 to 2.947g./ml., the latter resulting in a twentyfold range of density differences. The drop viscosities had no apparent effect.
Absorption of ethylene oxide in a packed column with various solvents
Authors: Bonilla C F. , Baron S.
Published: June 2004

Data were obtained on the solubility of ethylene oxide gas in a number of aqueous and nonaqueous solvents at various temperatures and gas concentrations. Its absorption from high concentrations in air was studied in a packed column with a cooling jacket for removal of the heat evolved. The results can be correlated with adequate accuracy in terms of the conditions at the top or dilute end of the column. The values of (H.T.U.)G and (H.T.U.)L agree approximately with known values for other systems. For the solvents tested, the liquid‐film resistance is controlling at room temperatures.
Transport of momentum and energy in a ducted jet: I. Experimental study of a nonisothermal jet of air discharging into a duct
Authors: Alexander L. G. , Kivnick Arnold , Comings E. W. , Henze E. D.
Published: June 2004

A heated jet of air from an 0.898‐in. standard A.S.M.E. nozzle was discharged into a 4‐in. steel duct, well insulated over its entire 10‐ft. length. Air from the region surrounding the nozzle was entrained into the duct. At a number of points along the duct, radial profiles of air velocity and temperature were obtained by means of a probe which combined an impact tube and a thermocouple. The temperature at each of several points along the duct wall was indicated by thermocouples imbedded in the wall.

In the experiments reported here the velocity at the jet was 585 ft./sec.; the temperature of the jet was about 220°F. and that of the entrained air was about 88°F. The total air flow rate through the duct was 0.67 lb./sec., and the heat flux was 4.9 B.t.u./sec., with the temperature of the entrained air taken as the datum.

The radial and axial profiles of velocity and temperature are compared and discussed; the temperatures of the stream near the duct wall and of the duct wall itself are given. Conservation of mass and heat was checked by graphical integration of the radial profiles.
Use of the redlich and kwong equation of state in calculating thermodynamic properties of gases from experimental compressibility data
Authors: Van Ness Hendrick C.
Published: June 2004

Convenient and accurate methods of calculating the thermodynamic properties of gases from experimental compressibility‐factor data through the use of the Redlich and Kwong equation of state are presented. Analytical and graphical methods are combined. As an example, fugacity and activity coefficients are calculated for the nitrogen‐ethylene system at 50°C. for pressures up to 500 atm.
Kinetics of the catalyzed and uncatalyzed liquid‐phase hydration of propylene oxide
Authors: Benham A. L. , Kurata Fred
Published: June 2004

The kinetics of the catalytic and noncatalytic hydration of propylene oxide were studied in a continuous reactor. Both the catalytic and noncatalytic reaction were studied over a temperature range of 100° to 300°F. The feed ratios ranged from 2.5 to 10 lb. water/lb. propylene oxide. In the case catalytic reaction, the catalyst concentration of sulfuric acid ranged up to 0.25 wt. % of the total feed.

The study showed the noncatalytic reaction to be pseudo first order with respect to propylene oxide, and an equation was found for the rate constant. The catalytic reaction was found to be pseudo second order with respect to propylene oxide, and the effect of the catalyst concentration is shown graphically.
Critical constants of unsaturated aliphatic hydrocarbons
Authors: Thodos George
Published: June 2004

The van der Waals' constanta a andb evaluated from structural considerations of the unsaturated aliphatic hydrocarbons are used to calculate the critical constants for these types of compounds. For these unsaturated hydrocarbons, both van der Waals' constants are calculated through the additive contribution of unsaturated bonds to the van der Waals' constants of the corresponding saturated aliphatic hydrocarbons calculated according to a method previously proposed (6).

With both van der Waals' constants available, the critical temperatures, pressures, and volumes for these types of compounds can be obtained.

By use of this approach, the critical temperatures, pressures, and volumes of several olefins, diolefins, and acetylenes have been calculated. These calculated values have been compared whenever possible with values reported in the literature to produce an average percentage deviation of 1.3 for the critical temperature, 3.0 for the critical pressure, and 1.5 for the critical volume. In this comparison questionable literature values have been included, and consequently the reported deviations present the worst possible expectation.
Gas absorption in beds of rings and saddles
Authors: Leva Max
Published: June 2004

New data are presented for the system carbon dioxide—sodium hydroxide. The effect of CO3= build‐up upon KGa values was investigated first and the data were then used to construct a curve by means of which all data were corrected to an arbitrarily chosen reference state of 25% CO3= concentration. KGa values increased with increasing liquid rate but were not dependent on gas rate if the packings were operated below loading. For some packings examined in the loading range, however, KGa values increased with increasing gas rate.

KGa values examined in relation to specific surface area were found to be very irregular in connection with rings. The surface‐area utilization pattern of the saddles was considerably more uniform. The ring and saddle data for the carbon dioxide‐sodium hydroxide system were in good qualitative agreement with the ammonia absorption data of Fellinger and the water‐water vapor data of Mehta and Parekh.
Total pressure method for vapor‐liquid equilibria at low absolute pressures: Aniline‐nitrobenzene systems
Authors: Holzlander G. W. , Riggle J. W.
Published: June 2004

Binary vapor‐liquid equilibrium data for use in the successful design and operation of mass transfer equipment at pressures down to approximately 5 mm. Hg may be advantageously obtained by the method of total pressures. In this method the desired equilibrium data are derived from pressure vs. temperature measurements on a convnient number of made‐up solutions covering the entire composition range.

With a modified Smith and Menzies isoteniscope, it is possible to measure accurately the data required for making the equilibrium calculations down to 2 mm. abs. pressure without the “bumping,” supercooling, and superheating encountered with equilibrium stills. The isoteniscope is simple to construct and operate from 1 atm. to 2 mm. abs.

The use of the total pressure method and the isoteniscope is illustrated by the determination of the vapor‐liquid equilibrium in the aniline‐nitrobenzene system at 5 and 10 mm. abs. In nineteen out of twenty instances the vapor compositions for a given liquid composition are precise to within ± 0.9% and the relative volatility, which varied between 2.54 and 1.85 over the composition and temperature ranges, is precise within ± 1.5%.
Effect of drying conditions on drying rate and physical properties of a porous solid
Authors: Lebeis E. H. , Burtis T. A.
Published: June 2004

Rate data are presented for both the constant ‐ and the falling‐rate drying of closely sized spheres of silica‐alumina hydrogel. This hydrogel, which contains a fine powder, is the starting material from which petroleum cracking catalysts may be prepared. During the constant‐rate period the drying rate is directly proportional to the difference between the dry‐ and wet‐bulb temperatures of the air. In the falling‐rate period the rate is proportional to the free water content, the proportionality factor being an undetermined function of the dry‐bulb‐wet‐bulb differential.

Drying severity during the falling‐rate period is shown to be the major determinant of the final pellet density. At constant wet‐bulb temperature, density is inversely related to the dry‐bulb‐wet‐bulb differential. If this differential is held constant, density is directly related to the wet‐bulb temperature.

The variation in drying rate with position in the bed for through‐circulation constant‐rate drying of deep beds of particles is analyzed for the case where the direction of air flow is periodically reversed for equal time intervals. It is indicated that uniformity of drying should increase with an increase in air velocity, but decrease as bed depth is increased. At constant conditions and bed depth, large particles should dry more uniformly than small. Within normal operating ranges, air temperature and humidity should have little effect on drying uniformity.
Analysis of gas‐fluidized solid systems by x‐ray absorption
Authors: Grohse E. W.
Published: June 2004

X‐ray absorption is presented as a unique tool for the study of the fundamentals of gas fludization. For example, bed‐density profiles, valuable indexes of the quality of fluidization, are readily determined by means of X‐ray absorption. No internal probes, to interfere with the normal action within a fluidized bed, are involved.

As an initial application of X‐ray absorption to fluidization, the results of a study of the effect of mode of distribution of gas to a fluidized bed are presented. The importance of this variable, only superficially discussed in previous literature, is clearly shown by these results. Application of X‐ray absorption to other chemical engineering operations is readily conceivable.
Mechanism of heat transfer to fluidized beds
Authors: Mickley H. S. , Fairbanks D. F.
Published: June 2004

In order to determine the nature of the resistance controlling heat transfer between fluidized beds and surfaces in contact with them, heat transfer measurements were made on the same solid constituents with several different fluidizing gases. The heat transfer coefficients obtained with fluidized beds are found to be proportional to the square root of the thermal conductivity of the quiescent beds. This result indicates that the process controlling fluidized heat transfer may be considered to be an unsteady‐state diffusion of heat into mobile elements of quiescent bed material.

This picture is analyzed mathematically to yield an equation for the heat transfer coefficient h = h \documentclass{article}\pagestyle{empty}\begin{document}$ h = \sqrt {{\rm K}_{\rm m} \rho _{\rm m} cS} $\end{document} wherein the effects of the bed thermal properties are separated from the effects of the stirring factor S, which accounts for bed motion and geometry. The mass transfer analogue is also derived and shown to correlate existing mass and heat transfer data reasonably well.

It is concluded that the proposed mechanism yields a satisfactory picture of the fluidized heat transfer process and may provide the beginnings of a rational approach to the correlation and prediction of fluidized heat transfer in engineering work.
Continuous stirred tank reactors: A new graphical method for complex reaction and reflux designs
Authors: Bilous Olegh , Piret Edgar L.
Published: June 2004

The usual graphical CSTR design methods are not adequate for the case of complex reactions involving competing or consecutive steps; therefore graphical design method based on the representation of batch data on a triangular diagram is given and illustrated by several examples. This method does not require a complete analysis of the kinetics of the reaction. Since material balances are easily represented on concentration spaces, the method is especially useful when the design includes recycling, or feed additions along reactor chain.
Kinetics of the liquid‐phase oxidation of ethanol
Authors: Klassen John , Kirk R. S.
Published: June 2004

A study was made of the rate of liquid‐phase oxidation of ethanol to acetic acid. An aqueous, basic solution of ethanol was allowed to trickle over a palladium‐onalumina catalyst in a packed tower while oxygen‐containing gas was blown upward. The observed rates are described by an equation including a kinetic term and a mass transfer term for the diffusion of oxygen. Kinetic rate constants and gas‐ and liquid‐film mass transfer coefficients are reported.
Numerical solution of two‐dimensional heat‐flow problems
Authors: Douglas Jim , Peaceman D. W.
Published: June 2004

Two‐dimensional heat flow frequently leads to problems not amenable to the methods of classical mathematical physics; thus, procedures for obtaining approximate solutions are desirable. A recently introduced finite‐difference method, known to be applicable to problems in a rectangular region and involving much less calculation than previous methods, is extended by example to cases of more practical interest. Although all three examples given are steady state, unsteady state problems may also be attacked successfully by the method. The first example is that of flow around a corner and indicates that a more complicated region than a rectangle can be treated. Then a problem involving a radiation‐boundray condition is given; as this condition is nonlinear, the method is extended to more general equations. The last example involves point heat sources and sinks in an elliptical region and so extends the method to treat curved boundaries (as distinguished from polygonal domains) and singular points. It is believed that materially less calculation is necessary by this method than for previous procedures.
Plant performance of a 13‐ft.‐diameter extractive‐distillation column
Authors: Gerster J. A. , Mizushina Tokuro , Marks T. N. , Catanach A. W.
Published: June 2004

Plant performance data are presented for a 13‐ft.‐diam., 100‐tray furfural extractive‐distillation column separating iso‐ and n‐butane from 1‐ and 2‐butene. In addition to composition, temperature, pressure, and flow rate of the external streams, values are presented for vapor and liquid compositions and flow rates at a number of different locations within the tower. With the exception of the vapor compositions, which were determined experimentally, the internal conditions were determined by heat and material balances. These data permitted calculation of plate efficiency over various small sections of the column. In the 50‐tray rectifying section, plate efficiency for the isobutane—1‐butene separation was constant at 20%, and in the stripping section the plate efficiency varied from 25 to 45%. The average for the entire column was 25%.

The furfural‐column plate efficiencies compare favorably with those predicted from laboratory tests made before the construction of the column to evaluate the performance of the tray design to be employed. The laboratory plate efficiencies were obtained for the desorption of oxygen from oxygen‐rich water with air at the same conditions of volumetric gas and liquid rates to be encountered in the furfural column. When these values were suitably corrected for physical property differences between the two systems, the point efficiencies predicted from the laboratory data for the furfural column ranged from 35% near the top of the column to 25% near the bottom of the column, the average value being 29%.
An algebraic approach to calculating the solvent extraction of complex mixtures
Authors: Hopp Harry F. , Smith R. B.
Published: June 2004

In the usual method of calculating the solvent extraction of complex mixtures it is assumed that the complex mixture behaves like a binary mixture. However, the hypothetical binary composition of the mixture is never explicitly used; rather, an additive property of the mixture is used as an indication of its composition. The calculation must be done graphically on a triangular diagram or its equivalent.

On the assumption that the complex mixture consists of only two hypothetical components, empirical equations have been arrived at relating the distribution coefficients of these two components and of the solvent to the phase compositions. These equations contain three arbitrary constants. By use of the data from a minimum of three simple laboratory batch extractions of a given complex mixture, the three constants, plus the hypothetical binary composition of the original complex mixture, can be determined.

With the equations for the distribution coefficients, the equilibrium curve and tie lines for the system can be calculated. Properties of the raffinates and extracts can be measured and related to the hypothetical binary compositions of these mixtures.

The use of the method is demonstrated by comparing calculated results with laboratory yields and properties. The calculated results show good agreement with the experimental results. Calculations can be carried out not only on the triangular diagram, but by any of the other graphical methods that have been developed for the solvent extraction of binary mixtures. Equally important, calculations can be done analytically, and therefore the use of automatic computers is feasible.
Determination of relative permeability under simulated reservoir conditions
Authors: Wilson J. W.
Published: June 2004

An apparatus for the determination of relative permeability under simulated reservoir conditions has been designed, constructed, and operated successfully. Complete water‐oil relative‐permeability data, with kerosene and simulated reservoir brine have been taken on four natural‐sandstone cores at fluid pressures to 5,000 1b./sq. in. and overburden pressures to 10,000 1b./sq. in. One run was made at low pressure at a temperature of 160°F. for comparison with the results at low temperature. The apparatus is now being expanded so that gas‐oil relative‐permeability data may be taken, and crude oil containing gas in solution may be employed as the oil phase.

The results indicate that essentially the same water‐oil relative‐permeability data are obtained at fluid pressures of 5,000 1b./sq. in. as at 30 1b./sq. in. gauge. The application of overburden pressure causes a reduction in both water and oil effective permeability in about the same proportion as it affects the single‐phase permeability. Consequently the calculated relative permeabilities are affected to only a moderate extent. The results of the one run at 160°F. were in good agreement with the values obtained at room temperature.
Properties of evaporated metal films related to their use for surface temperature measurements
Authors: Simpson Theodore B. , Winding Charles C.
Published: June 2004

Extension of the understanding of properties of films of metals produced on glass surfaces by vacuum evaporation has permitted the fabrication of film‐resistance thermometers that with simple instrumentation accurately measure surface or average surface temperatures without altering the geography of that surface. Formerly unknown and unstabled related properties of such films have been classified and may be anticipated or eliminated by recommended experimental procedures. Films of several of the most chemically inert and refractory metals 300 to 3,000 Å. thick have been shown to attain accuracies as high as 0.01°C. for practical periods of time. Their use, which is described, is developing satisfactorily, and the technique and equipment for their preparation are relatively simple.
Effect of gamma radiation on aqueous ethylene‐oxygen solutions
Authors: Henley Ernest J. , Schiffries Wesley P. , Barr Nathaniel F.
Published: June 2004

Mixtures of ethylene and oxygen dissolved in water under pressures ranging from 200 to 700 lb./sq. in. were irradiated with Co60 gamma rays at a dose rate of 180,000 r./hr. G values (molecules/100 ev.) for aldehyde production as high as 200 were observed. Increasing total pressure and dose were found to decrease these G values. Alcohol, acids, hydrogen peroxide, and organic peroxide are also products of the reaction; however, the yields are much smaller.
Heat transfer to water flowing parallel to a rod bundle
Authors: Miller Philip , Byrnes James J. , Benforado David M.
Published: June 2004

Heat transfer was measured for water flowing parallel to 5/8‐in. rods in a triangular lattice (0.914‐in. spacing). Velocity was varied from 5 to 20 ft./sec., temperature from 150° to 325°F., and heat flux from 50,000 to 200,000 B.t.u./(hr.)(sq. ft.). Reynolds numbers ranged from 70,000 to 700,000. Coefficients were 40% higher than predicted from the Colburn equation for flow in pipes by use of the equivalent diameter. The effect of heated length was studied. No variation in local coefficient around the rod periphery was found. Pressure drops were 65% higher than predicted by the Fanning equation (by use of De).
Factorial experiments in sequence: The attainment of optimum conditions for a decontamination process
Authors: Barnett M. K. , Hamilton P. M. , Mead F. C.
Published: June 2004

The advantages of factorial design are first illustrated by a simple experiment devoted to the effect of two pH factors and an iron‐concentration factor on the efficiency of a decontamination process employing iron sulfide as a scavenging agent. The broadening of the base of an investigation by the expansion of a factorial is illustrated by addition of the sulfide concentration as a factor. Finally the principle of expanded factorials is further utilized in the later phases of the study, in which additional levels are assigned to the pH factors in order to arrive at a closer estimate of the optimum conditions for the process.
A common basis for the correlation of forced and natural convection to horizontal cylinders
Authors: Lemlich Robert , Hoke Ronald
Published: June 2004

Natual and forced convection have always been correlated on different bases although the two phenomena have much in common. Accordingly, a method for correlating both types of convection on the same basis, at least for heat transfer outside horizontal cylinders, would be of interest.

A tentative method of accomplishing this for transverse convection is presented, involving certain simplifying assumptions relating to drag and buoyancy, from which an “effective velocity” for natural convection is calculated (by means of the well‐known drag correlation) and incorporated in a Reynolds number. The Nusselt number for natural convection is then correlated in terms of the Prandtl number and this Reynolds number in much the same manner as that for McAdams's well‐known correlation for forced convection. For 150 different combinations of independent variables covering seven different fluids and wide ranges of diameter, surface temperature, and bulk fluid temperature, the transformed natural‐convection data agree with Douglas and Churchill's recent refinement of McAdams's relationship for forced convection with an average deviation of about ±10%.
A semiempirical solution for local heat transfer coefficients for flow in nonparallel passageways
Authors: Stevens P. N. , Obert E. F.
Published: June 2004

A method, based upon the pertinent flat‐plate heat transfer equation, is presented for computing the local heat transfer coefficients for a boundary layer subjected to streamwise velocity and pressure gradients. No extensive mathematical background is required as the complexity of a rigorous solution for this type of problem is avoided. The validity of the method for gases is demonstrated by comparison of the predicted coeffcients with the experimental data for two widely different problems.
Application of Bernoulli's equation to buoyant systems
Authors: Ruth B. F. , Boylan D. R.
Published: June 2004

The various forms of Bernoulli's equation as customarily written express static pressure energy in terms of absolute pressure, thereby restricting their direct application to systems situated in vacuo. It is shown here that recognition (1) of the universal presence of a fluid outside all systems over which Bernoulli's equation is written, and (2) of the practical necessity of measuring pressure within such systems as gauge pressures relative to the pressure of the exterior fluid leads to a more general set of equations and to a concept of buoyant static pressure and potential energies, as opposed to strictly abslute values.

Failure properly to distinguish between these two types of energy quantities may result in error and confusion in the application of the various forms of Bernoulli's equation.
Operating characteristics of a centrifugal extractor
Authors: Jacobsen F. M. , Beyer G. H.
Published: June 2004

The operating characteristics of a Podbielniak model 5,000 centrifugal extractor, having a combined‐stream capacity of 450 cc./min. at 5,000 rev./min. and a rotor holdup of 529 cc., were investigated. Variables studied were density difference, rotor speed, light‐liquid‐out pressure, flow rates, holdup, and number of stages.

A technique for holdup determination that comprises displacing either phase in the extractor with the other phase is described and experimentally demonstrated. An equation useful in predicting flooding limits is verified. It is suggested that the effective values of the rotor dimensions in this equation be determined by the behavior of the extractor.

A relationship among number of stages, light‐liquid‐out pressure, and flow‐rate ratio is demonstrated by extracting boric acid from isoamyl alcohol with water. With only a few runs this relationship should permit one to map in a family of curves for a particular system and thus rapidly to estimate optimum operating conditions.

A procedure is outlined for applying the methods to other systems using similar extractors. First the constants in an equation are estimated from holdup measurements in order to predict flooding limits. Then a few extraction runs are made to estimate optimum operating conditions.