bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Endothelial Glycocalyx Degradation and Surfactants on Air Embolism Adhesion
Authors: Eckmann David M. , Armstead Stephen C.
Published: November 2006

Background

Microbubble adherence to endothelial cells is enhanced after damage to the glycocalyx. The authors tested the hypothesis that exogenous surfactants delivered intravascularly have differential effects on the rate of restoration of blood flow after heparinase-induced degradation of the endothelial glycocalyx.

Methods

Air microbubbles were injected into the rat cremaster microcirculation after perfusion with heparinase or saline and intravascular administration of either saline or one of two surfactants. The surfactants were Pluronic F-127 (Molecular Probes, Eugene, OR) and Perftoran (OJSC SPC Perftoran, Moscow, Russia). Embolism dimensions and dynamics were observed using intravital microscopy.

Results

Significant results were that bubbles embolized the largest diameter vessels after glycocalyx degradation. Bubbles embolized smaller vessels in the surfactant treatment groups. The incidence of bubble dislodgement and the magnitude of distal displacement were smallest after glycocalyx degradation alone and largest after surfactant alone. The time to bubble clearance and restoration of blood flow was longest with heparinase alone and shortest with Pluronic F-127 alone.

Conclusions

Degradation of the glycocalyx causes air bubbles to adhere to the endothelium more proximally in the arteriolar microcirculation. Surfactants added after glycocalyx degradation and before gas embolization promotes bubble lodging in the distal microcirculation. Surfactants may have a clinical role in reducing embolism bubble adhesion to endothelial cells undergoing glycocalyx disruption.
Effect of High- and Low-molecular-weight Low-substituted Hydroxyethyl Starch on Blood Coagulation during Acute Normovolemic Hemodilution in Pigs
Authors: Thyes Caroline , Madjdpour Caveh , Frascarolo Philippe , Buclin Thierry , Bürki Marco , Fisch Andreas , Burmeister Marc-Alexander , Asmis Lars , Spahn Donat R.
Published: November 2006

Background

Hydroxyethyl starches (HES) with lower impact on blood coagulation but longer intravascular persistence are of clinical interest. The current study aimed to investigate in vivo the isolated effect of molecular weight on blood coagulation during progressive acute normovolemic hemodilution.

Methods

Twenty-four pigs were normovolemically hemodiluted up to a total exchange of 50 ml . kg . body weight of HES 650/0.42 or HES 130/0.42. Serial blood sampling was performed to measure HES plasma concentration and to assess blood coagulation. Concentration-effect relations were analyzed by linear regression, followed by the Student t test on regression parameters.

Results

Blood coagulation was increasingly compromised toward hypocoagulability by acute normovolemic hemodilution with both treatments (P < 0.01). Significantly greater impact on activated partial thromboplastin time (P = 0.04) and significantly stronger decrease of maximal amplitude (P = 0.04), angle alpha (P = 0.02), and coagulation index (P = 0.02) was seen after acute normovolemic hemodilution with HES 650/0.42 as compared with HES 130/0.42. Except for factor VIII (P = 0.04), no significant differences between both treatments were observed when relating antihemostatic effects to HES plasma concentrations (P > 0.05). A significantly lesser decrease of hemoglobin concentration has been found with HES 650/0.42 as compared with HES 130/0.42 (P < 0.01) in relation to HES plasma concentrations.

Conclusion

High-molecular-weight HES (650/0.42) shows a moderately greater antihemostatic effect than low-molecular-weight HES (130/0.42) during acute normovolemic hemodilution. However, similar effects on hemostasis were observed with both treatments when observed antihemostatic effects were related to measured HES plasma concentrations. In addition, HES 650/0.42 may have a lower efficacy in immediately restoring plasma volume.
Retropharyngeal Hematoma after Stellate Ganglion Block
Authors: Higa Kazuo , Hirata Kazuhiko , Hirota Kazunori , Nitahara Keiichi , Shono Shinjiro
Published: November 2006

Background

Retropharyngeal hematoma (RPH) is rare; however, it causes airway obstruction and can be fatal. Stellate ganglion block (SGB) can cause RPH. The authors analyzed reports of patients with RPH after SGB to clarify the initial symptoms and signs, and the urgency of airway management.

Methods

MEDLINE and Japana Centra Revuo Medicina were searched for reports of RPH after SGB using the following terms and key words: stellate ganglion block, complication, hematoma, and retropharyngeal hematoma.

Results

The authors found 27 patients with RPH after SGB in the past 40 yr. The initial symptoms included neck pain (n = 10), dyspnea (n = 10), neck swelling (n = 8), and hoarseness (n = 5). The symptoms occurred 2 h or more after SGB in 14 patients (52%). Emergency airway management was needed in 21 patients (78%) because of airway obstruction. Among the 21 patients, orotracheal intubation was attempted first in 17 patients; however, it was unsuccessful in 5 patients who immediately needed emergency tracheostomy. Tracheal intubation was impossible by distortion of the anatomy of the markedly edematous pharyngolarynx. Failed airway management caused one death. There were no statistically significant predictors of the initial symptoms or signs for later emergency airway management.

Conclusions

RPH after SGB necessitates emergency airway management. Because airway obstruction cannot be predicted by the initial symptoms or signs, emergency airway management tools should be at hand, and the patency of the airway should be continuously evaluated after onset of RPH after SGB.
Value of Preoperative Clinic Visits in Identifying Issues with Potential Impact on Operating Room Efficiency
Authors: Correll Darin J. , Bader Angela M. , Hull Melissa W. , Hsu Cindy , Tsen Lawrence C. , Hepner David L.
Published: November 2006

Background

Preoperative clinics have been shown to decrease operating room delays and cancellations. One mechanism for this positive economic impact is that medical issues are appropriately identified and necessary information is obtained, so that knowledge of the patients' status is complete before the day of surgery. In this study, the authors describe the identification and management of medical issues in the preoperative clinic.

Methods

All patients coming to the Preoperative Clinic during a 3-month period from November 1, 2003, through January 31, 2004, at the Brigham and Women's Hospital, Boston, Massachusetts, were studied. Data were collected as to the type of issue, information needed to resolve the issue, time to retrieve the information, cancellation and delay rates, and the effect on management.

Results

A total of 5,083 patients were seen in the preoperative clinic over the three-month period. A total of 647 patients had a total of 680 medical issues requiring further information or management. Of these issues, 565 were thought to require further information regarding known medical problems, and 115 were new medical problems first identified in the clinic. Most of the new problems required that a new test or consultation be done, whereas most of the old problems required retrieval of information existing from outside medical centers. New problems had a far greater probability of delay (10.7%) or cancellation (6.8%) than old problems (0.6% and 1.8%, respectively).

Conclusions

The preoperative evaluation can identify and resolve a number of medical issues that can impact efficient operating room resource use.
Improved Postoperative Outcomes Associated with Preoperative Statin Therapy
Authors: Hindler Katja , Shaw Andrew D. , Samuels Joshua , Fulton Stephanie , Collard Charles D. , Riedel Bernhard , Warltier David C.
Published: November 2006

Statin therapy is well established for prevention of cardiovascular disease. Statins may also reduce postoperative mortality and morbidity via a pleiotropic (non-lipid-lowering) effect. The authors conducted a meta-analysis to determine the influence of statin treatment on adverse postoperative outcomes in patients undergoing cardiac, vascular, or noncardiovascular surgery. Two independent authors abstracted data from 12 retrospective and 3 prospective trials (n = 223,010 patients). A meta-analysis was performed to evaluate the overall effect of preoperative statin therapy on postoperative outcomes. Preoperative statin therapy was associated with 38% and 59% reduction in the risk of mortality after cardiac (1.9% vs. 3.1%; P = 0.0001) and vascular (1.7% vs. 6.1%; P = 0.0001) surgery, respectively. When including noncardiac surgery, a 44% reduction in mortality (2.2% vs. 3.2%; P = 0.0001) was observed. Preoperative statin therapy may reduce postoperative mortality in patients undergoing surgical procedures. However, the statin associated effects on postoperative cardiovascular morbidity are too variable to draw any conclusion.
Wnt/β-catenin signaling regulates vertebrate limb regeneration
Authors: Kawakami Yasuhiko , Rodriguez Esteban Concepción , Raya Marina , Kawakami Hiroko , Martí Mercè , Dubova Ilir , Izpisúa Belmonte Juan Carlos
Published: November 2006

The cellular and molecular bases allowing tissue regeneration are not well understood. By performing gain- and loss-of-function experiments of specific members of the Wnt pathway during appendage regeneration, we demonstrate that this pathway is not only necessary for regeneration to occur, but it is also able to promote regeneration in axolotl, Xenopus, and zebrafish. Furthermore, we show that changes in the spatiotemporal distribution of β-catenin in the developing chick embryo elicit apical ectodermal ridge and limb regeneration in an organism previously thought not to regenerate. Our studies may provide valuable insights toward a better understanding of adult tissue regeneration.
A PHD finger protein involved in both the vernalization and photoperiod pathways in Arabidopsis
Authors: Sung Sibum , Schmitz Robert J. , Amasino Richard M.
Published: November 2006

The proper timing of flowering is critical for successful reproduction. The perception of the seasonal cues of day-length changes and exposure to cold influences flowering time in many plant species through the photoperiod and vernalization pathways, respectively. Here we show that a plant homeodomain (PHD) finger-containing protein, VIN3-LIKE 1 (VIL1), participates in both the photoperiod and vernalization pathways in Arabidopsis thaliana by regulating expression of the related floral repressors FLOWERING LOCUS C (FLC) and FLOWERING LOCUS M (FLM). In the vernalization pathway, VIL1, along with VERNALIZATION INSENSITIVE 3 (VIN3), is necessary for the modifications to FLC and FLM chromatin that are associated with an epigenetically silenced state and with acquisition of competence to flower. In addition, VIL1 regulates FLM independently of VIN3 in a photoperiod-dependent manner.
The Mechanical Diversity of Stomata and Its Significance in Gas-Exchange Control
Authors: Franks Peter J. , Farquhar Graham D.
Published: November 2006

Given that stomatal movement is ultimately a mechanical process and that stomata are morphologically and mechanically diverse, we explored the influence of stomatal mechanical diversity on leaf gas exchange and considered some of the constraints. Mechanical measurements were conducted on the guard cells of four different species exhibiting different stomatal morphologies, including three variants on the classical “kidney” form and one “dumb-bell” type; this information, together with gas-exchange measurements, was used to model and compare their respective operational characteristics. Based on evidence from scanning electron microscope images of cryo-sectioned leaves that were sampled under full sun and high humidity and from pressure probe measurements of the stomatal aperture versus guard cell turgor relationship at maximum and zero epidermal turgor, it was concluded that maximum stomatal apertures (and maximum leaf diffusive conductance) could not be obtained in at least one of the species (the grass Triticum aestivum) without a substantial reduction in subsidiary cell osmotic (and hence turgor) pressure during stomatal opening to overcome the large mechanical advantage of subsidiary cells. A mechanism for this is proposed, with a corollary being greatly accelerated stomatal opening and closure. Gas-exchange measurements on T. aestivum revealed the capability of very rapid stomatal movements, which may be explained by the unique morphology and mechanics of its dumb-bell-shaped stomata coupled with “see-sawing” of osmotic and turgor pressure between guard and subsidiary cells during stomatal opening or closure. Such properties might underlie the success of grasses.
Decreases in Stomatal Conductance of Soybean under Open-Air Elevation of [CO2] Are Closely Coupled with Decreases in Ecosystem Evapotranspiration
Authors: Bernacchi Carl J. , Kimball Bruce A. , Quarles Devin R. , Long Stephen P. , Ort Donald R.
Published: November 2006

Stomatal responses to atmospheric change have been well documented through a range of laboratory- and field-based experiments. Increases in atmospheric concentration of CO2 ([CO2]) have been shown to decrease stomatal conductance (g  s) for a wide range of species under numerous conditions. Less well understood, however, is the extent to which leaf-level responses translate to changes in ecosystem evapotranspiration (ET). Since many changes at the soil, plant, and canopy microclimate levels may feed back on ET, it is not certain that a decrease in g  s will decrease ET in rain-fed crops. To examine the scaling of the effect of elevated [CO2] on g  s at the leaf to ecosystem ET, soybean (Glycine max) was grown in field conditions under control (approximately 375 μmol CO2 mol−1 air) and elevated [CO2] (approximately 550 μmol mol−1) using free air CO2 enrichment. ET was determined from the time of canopy closure to crop senescence using a residual energy balance approach over four growing seasons. Elevated [CO2] caused ET to decrease between 9% and 16% depending on year and despite large increases in photosynthesis and seed yield. Ecosystem ET was linked with g  s of the upper canopy leaves when averaged across the growing seasons, such that a 10% decrease in g  s results in a 8.6% decrease in ET; this relationship was not altered by growth at elevated [CO2]. The findings are consistent with model and historical analyses that suggest that, despite system feedbacks, decreased g  s of upper canopy leaves at elevated [CO2] results in decreased transfer of water vapor to the atmosphere.
Short Vegetative Phase-Like MADS-Box Genes Inhibit Floral Meristem Identity in Barley
Authors: Trevaskis Ben , Tadege Million , Hemming Megan N. , Peacock W. James , Dennis Elizabeth S. , Sheldon Candice
Published: November 2006

Analysis of the functions of Short Vegetative Phase (SVP)-like MADS-box genes in barley (Hordeum vulgare) indicated a role in determining meristem identity. Three SVP-like genes are expressed in vegetative tissues of barley: Barley MADS1 (BM1), BM10, and Vegetative to Reproductive Transition gene 2. These genes are induced by cold but are repressed during floral development. Ectopic expression of BM1 inhibited spike development and caused floral reversion in barley, with florets at the base of the spike replaced by tillers. Head emergence was delayed in plants that ectopically express BM1, primarily by delayed development after the floral transition, but expression levels of the barley VRN1 gene (HvVRN1) were not affected. Ectopic expression of BM10 inhibited spike development and caused partial floral reversion, where florets at the base of the spike were replaced by inflorescence-like structures, but did not affect heading date. Floral reversion occurred more frequently when BM1 and BM10 ectopic expression lines were grown in short-day conditions. BM1 and BM10 also inhibited floral development and caused floral reversion when expressed in Arabidopsis (Arabidopsis thaliana). We conclude that SVP-like genes function to suppress floral meristem identity in winter cereals.
Cold Transiently Activates Calcium-Permeable Channels in Arabidopsis Mesophyll Cells
Authors: Carpaneto Armando , Ivashikina Natalya , Levchenko Victor , Krol Elzbieta , Jeworutzki Elena , Zhu Jian-Kang , Hedrich Rainer
Published: November 2006

Living organisms are capable of discriminating thermal stimuli from noxious cold to noxious heat. For more than 30 years, it has been known that plant cells respond to cold with a large and transient depolarization. Recently, using transgenic Arabidopsis (Arabidopsis thaliana) expressing the calcium-sensitive protein aequorin, an increase in cytosolic calcium following cold treatment was observed. Applying the patch-clamp technique to Arabidopsis mesophyll protoplasts, we could identify a transient plasma membrane conductance induced by rapid cooling. This cold-induced transient conductance was characterized as an outward rectifying 33 pS nonselective cation channel. The permeability ratio between calcium and cesium was 0.7, pointing to a permeation pore >3.34 Å (ø of cesium). Our experiments thus provide direct evidence for the predicted but not yet measured cold-activated calcium-permeable channel in plants.
Insights into the Role of Specific Lipids in the Formation and Delivery of Lipid Microdomains to the Plasma Membrane of Plant Cells
Authors: Laloi Maryse , Perret Anne-Marie , Chatre Laurent , Melser Su , Cantrel Catherine , Vaultier Marie-Noëlle , Zachowski Alain , Bathany Katell , Schmitter Jean-Marie , Vallet Myriam , Lessire René , Hartmann Marie-Andrée , Moreau Patrick
Published: November 2006

The existence of sphingolipid- and sterol-enriched microdomains, known as lipid rafts, in the plasma membrane (PM) of eukaryotic cells is well documented. To obtain more insight into the lipid molecular species required for the formation of microdomains in plants, we have isolated detergent (Triton X-100)-resistant membranes (DRMs) from the PM of Arabidopsis (Arabidopsis thaliana) and leek (Allium porrum) seedlings as well as from Arabidopsis cell cultures. Here, we show that all DRM preparations are enriched in sterols, sterylglucosides, and glucosylceramides (GluCer) and depleted in glycerophospholipids. The GluCer of DRMs from leek seedlings contain hydroxypalmitic acid. We investigated the role of sterols in DRM formation along the secretory pathway in leek seedlings. We present evidence for the presence of DRMs in both the PM and the Golgi apparatus but not in the endoplasmic reticulum. In leek seedlings treated with fenpropimorph, a sterol biosynthesis inhibitor, the usual Δ5-sterols are replaced by 9β,19-cyclopropylsterols. In these plants, sterols and hydroxypalmitic acid-containing GluCer do not reach the PM, and most DRMs are recovered from the Golgi apparatus, indicating that Δ5-sterols and GluCer play a crucial role in lipid microdomain formation and delivery to the PM. In addition, DRM formation in Arabidopsis cells is shown to depend on the unsaturation degree of fatty acyl chains as evidenced by the dramatic decrease in the amount of DRMs prepared from the Arabidopsis mutants, fad2 and Fad3+, affected in their fatty acid desaturases.
The Transcription Factors WRKY11 and WRKY17 Act as Negative Regulators of Basal Resistance inArabidopsis thaliana
Authors: Journot-Catalino Noëllie , Somssich Imre E. , Roby Dominique , Kroj Thomas
Published: November 2006

Transcription factors are believed to play a pivotal role in the activation and fine-tuning of plant defense responses, but little is known about the exact function of individual transcription factors in this process. We analyzed the role of the IId subfamily of WRKY transcription factors in the regulation of basal resistance to Pseudomonas syringae pv tomato (Pst). The expression of four members of the subfamily was induced upon challenge with virulent and avirulent strains of Pst. Mutant analyses revealed that loss of WRKY11 function increased resistance toward avirulent and virulent Pst strains and that resistance was further enhanced in wrky11 wrky17 double mutant plants. Thus, WRKY11 and WRKY17 act as negative regulators of basal resistance to Pst. Genome-wide expression analysis and expression studies of selected genes in single and double mutants demonstrated that both transcription factors modulate transcriptional changes in response to pathogen challenge. Depending on the target gene, WRKY11 and WRKY17 act either specifically or in a partially redundant manner. We demonstrate complex cross-regulation within the IId WRKY subfamily and provide evidence that both WRKY transcription factors are involved in the regulation of Pst-induced jasmonic acid–dependent responses. These results provide genetic evidence for the importance of WRKY11 and WRKY17 in plant defense.
Protein Polyubiquitination Plays a Role in Basal Host Resistance of Barley
Authors: Dong Wubei , Nowara Daniela , Schweizer Patrick
Published: November 2006

To study protein ubiquitination pathways in the interaction of barley (Hordeum vulgare) with the powdery mildew fungus (Blumeria graminis), we measured protein turnover and performed transient-induced gene silencing (TIGS) of ubiquitin and 26S proteasome subunit encoding genes in epidermal cells. Attack by B. graminis hyperdestabilized a novel unstable green fluorescent protein fusion that contains a destabilization domain of a putative barley 1-aminocyclopropane-1-carboxylate synthase, suggesting enhanced protein turnover. Partial depletion of cellular ubiquitin levels by TIGS induced extreme susceptibility of transformed cells toward the appropriate host pathogen B. graminis f. sp hordei, whereas papilla-based resistance to the nonhost pathogen B. graminis f. sp tritici and host resistance mediated by the mlo gene (for mildew resistance locus O) remained unaffected. Cells were rescued from TIGS-induced ubiquitin depletion by synthetic genes encoding wild-type or mutant barley monoubiquitin proteins. The strongest rescue was from a gene encoding a K63R mutant form of ubiquitin blocked in several ubiquitination pathways while still allowing Lys-48–dependent polyubiquitination required for proteasomal protein degradation. Systematic RNA interference of 40 genes encoding all 17 subunits of the proteasome 19S regulatory particle failed to induce hypersusceptibility against B. graminis f. sp hordei. This suggests a role for Lys-48–linked protein polyubiquitination, which is independent from the proteasome pathway, in basal host defense of barley.
ArabidopsisSLIM1 Is a Central Transcriptional Regulator of Plant Sulfur Response and Metabolism
Authors: Maruyama-Nakashita Akiko , Nakamura Yumiko , Tohge Takayuki , Saito Kazuki , Takahashi Hideki
Published: November 2006

Sulfur is an essential macronutrient required for plant growth. To identify key transcription factors regulating the sulfur assimilatory pathway, we screened Arabidopsis thaliana mutants using a fluorescent reporter gene construct consisting of the sulfur limitation-responsive promoter of the SULTR1;2 sulfate transporter and green fluorescent protein as a background indicator for monitoring plant sulfur responses. The isolated mutant, sulfur limitation1 (slim1), was unable to induce SULTR1;2 transcripts under low-sulfur (–S) conditions. Mutations causing the sulfur limitation responseless phenotypes of slim1 were identified in an EIL family transcription factor, ETHYLENE-INSENSITIVE3-LIKE3 (EIL3), whose functional identity with SLIM1 was confirmed by genetic complementation. Sulfate uptake and plant growth on –S were significantly reduced by slim1 mutations but recovered by overexpression of SLIM1. SLIM1 functioned as a central transcriptional regulator, which controlled both the activation of sulfate acquisition and degradation of glucosinolates under –S conditions. Metabolite analysis indicated stable accumulation of glucosinolates in slim1 mutants, even under –S conditions, particularly in the molecular species with methylsulfinylalkyl side chains beneficial to human health. Overexpression of SLIM1 and its rice (Oryza sativa) homologs, but no other EIL genes of Arabidopsis, restored the sulfur limitation responseless phenotypes of slim1 mutants, suggesting uniqueness of the SLIM1/EIL3 subgroup members as sulfur response regulators.
Arabidopsis Chromatin-Associated HMGA and HMGB Use Different Nuclear Targeting Signals and Display Highly Dynamic Localization within the Nucleus
Authors: Launholt Dorte , Merkle Thomas , Houben Andreas , Schulz Alexander , Grasser Klaus D.
Published: November 2006

In plants, the chromatin-associated high mobility group (HMG) proteins occur in two subfamilies termed HMGA and HMGB. The HMGA proteins are characterized by the presence of four AT-hook DNA binding motifs, and the HMGB proteins contain an HMG box DNA binding domain. As architectural factors, the HMG proteins appear to be involved in the regulation of transcription and other DNA-dependent processes. We have examined the subcellular localization of Arabidopsis thaliana HMGA, HMGB1, and HMGB5, revealing that they localize to the cell nucleus. They display a speckled distribution pattern throughout the chromatin of interphase nuclei, whereas none of the proteins associate with condensed mitotic chromosomes. HMGA is targeted to the nucleus by a monopartite nuclear localization signal, while efficient nuclear accumulation of HMGB1/5 requires large portions of the basic N-terminal part of the proteins. The acidic C-terminal domain interferes with nucleolar targeting of HMGB1. Fluorescence recovery after photobleaching experiments revealed that HMGA and HMGB proteins are extremely dynamic in the nucleus, indicating that they bind chromatin only transiently before moving on to the next site, thereby continuously scanning the genome for targets. By contrast, the majority of histone H2B is basically immobile within the nucleus, while linker histone H1.2 is relatively mobile.
The molecular composition of soil organic matter as determined by 13C NMR and elemental analyses and correlation with pesticide sorption
Authors: Ahmad R. , Nelson P. N. , Kookana R. S.
Published: November 2006

Although the chemical composition of soil organic matter (SOM) is known to significantly influence sorption of pesticides and other pollutants, it has been difficult to determine the molecular nature of SOM in situ. Here, using 13C nuclear magnetic resonance (NMR) data and elemental composition in a molecular mixing model, we estimated the molecular components of SOM in 24 soils from various agro‐ecological regions. Substantial variations were revealed in the molecular nature of SOM. As a proportion of soil carbon the proportion of the carbonyl component ranged from 0.006 to 0.05, charcoal from 0 to 0.15, protein from 0.09 to 0.29, aliphatic from 0.14 to 0.30, carbohydrate from 0.21 to 0.31, and lignin from 0.05 to 0.42. The relationships between Koc (sorption per unit mass of organic carbon) of carbaryl (1‐naphthyl methylcarbamate) and phosalone (S‐6‐chloro‐2,3‐dihydro‐2‐oxobenzoxazol‐3‐ylmethyl O,O‐diethyl phosphorodithioate) and the molecular nature of organic matter in the soils were significant. Of the molecular components estimated, lignin and charcoal contents correlated best with sorption of carbaryl and phosalone. Aliphatic, carbohydrate and protein contents were found to be negatively correlated with the Koc of both pesticides. The study highlights the importance of the molecular nature of SOM in determining sorption affinities of non‐ionic pesticides and presents an indirect method for sorption estimation of pesticides.
EFFECT OF CALCIUM AND PHOSPHORUS, RESIDUAL LACTOSE AND SALT‐TO‐MOISTURE RATIO ON TEXTURAL PROPERTIES OF CHEDDAR CHEESE DURING RIPENING
Authors: CHEVANAN N. , MUTHUKUMARAPPAN K. , UPRETI P. , METZGER L.E.
Published: November 2006

The texture profile analysis (TPA) parameters and meltability of Cheddar cheeses with varying levels of calcium (Ca) and phosphorus (P) content, residual lactose content and salt‐to‐moisture (S/M) ratio were studied at 0, 1, 2, 4, 6 and 8 months of ripening. The TPA hardness had an inverse relationship with the meltability of Cheddar cheese and at any given ripening time, lower TPA hardness corresponded to higher meltability of Cheddar cheese. Higher Ca and P content (0.67% Ca and 0.53% P) in Cheddar cheese resulted in up to 22.8, 5.7, 14.6, 13.5 and 35.2% increase in hardness, springiness, cohesiveness, resilience and chewiness values, respectively, and up to 23.5 and 27.7% decrease in meltability and adhesiveness values during ripening compared to the Cheddar cheese prepared with lower Ca and P content (0.53% Ca and 0.39% P). Higher residual lactose content (1.4%) in Cheddar cheese resulted in up to 24.6, 8.8 and 20.0% increase in hardness, cohesiveness and chewiness values, respectively, and up to 12.7% decrease in meltability value in the Cheddar cheese during ripening compared to the lower lactose content (0.78%). High S/M ratio (6.4) resulted in up to 29.4, 30.3 and 29.4% increase in hardness, adhesiveness and chewiness values, respectively, and up to 7.3% decrease in meltability value in Cheddar cheese compared to low S/M ratio (4.8) during ripening.
The Effects of Oblique Running and Ideal Motion on Stress Analysis of Bridge Crane Wheels
Authors: Demirsoy Mine
Published: November 2006

In this study, the effects of oblique running and ideal motion on the stresses of bridge crane wheels were examined. The stresses on the crane wheels were calculated using the rotation angles and the forces. The commercial finite element package I-DEAS was used for the solution of the problem. The technical values of two double girder bridge cranes with 32 and 50ton carrying capacities and 18m crane span were used. Finally, the stresses caused by the oblique running were compared with the ideal motion. The numerical results show that the stress values increase by the oblique running.
Topology Optimization Using a Hybrid Cellular Automaton Method With Local Control Rules
Authors: Tovar Andrés , Patel Neal M. , Niebur Glen L. , Sen Mihir , Renaud John E.
Published: November 2006

The hybrid cellular automaton (HCA) algorithm is a methodology developed to simulate the process of structural adaptation in bones. This methodology incorporates a distributed control loop within a structure in which ideally localized sensor cells activate local processes of the formation and resorption of material. With a proper control strategy, this process drives the overall structure to an optimal configuration. The controllers developed in this investigation include two-position, proportional, integral and derivative strategies. The HCA algorithm combines elements of the cellular automaton (CA) paradigm with finite element analysis (FEA). This methodology has proved to be computationally efficient to solve topology optimization problems. The resulting optimal structures are free of numerical instabilities such as the checkerboarding effect. This investigation presents the main features of the HCA algorithm and the influence of different parameters applied during the iterative optimization process.
Balancing Marketing and Manufacturing Objectives in Product Line Design
Authors: Michalek Jeremy J. , Ceryan Oben , Papalambros Panos Y. , Koren Yoram
Published: November 2006

The product development process involves communication and compromise among interacting and often competing objectives from marketing, design, and manufacturing perspectives. Methods for negotiating these perspectives play an important role in the process. For example, design for manufacturing (DFM) analyses aim to incorporate manufacturing requirements into product design decision making to reduce product complexity and cost, which generally increases profitability. However, when design characteristics have market consequences, it is important to quantify explicitly the tradeoffs between the reduced cost and reduced revenue resulting from designs that are less expensive to manufacture but also less desirable in the marketplace. In this article we leverage existing models for coordinating marketing and design perspectives by incorporating quantitative models of manufacturing investment and production allocation. The resulting methodology allows a quantitative assessment of tradeoffs among product functionality, market performance, and manufacturing costs to achieve product line solutions with optimal profitability.
Reduction of Stress Concentration in Bolt-Nut Connectors
Authors: Venkatesan Sriman , Kinzel Gary L.
Published: November 2006

Bolt-nut connectors play an important role in the safety and reliability of structural systems. Stress concentration due to unequal load distribution can cause fatigue failure in bolt-nut connectors. In this paper, the stress distribution in bolt-nut connectors is studied using an axisymmetric finite element model. Various geometric designs proposed in the literature were studied to determine the extent to which they reduce stress concentrations. Some well known modifications do significantly reduce the stress concentration factor (up to 85%) while other changes produce much more modest changes. The design modifications include things such as grooves and steps on the bolt and nut, and reducing the shank diameter of the bolt. All of the changes also result in a reduction in weight.
Velocity Effects on Robotic Manipulator Dynamic Performance
Authors: Bowling Alan P. , Kim ChangHwan
Published: November 2006

This article explores the effect that velocities have on a nonredundant robotic manipulator’s ability to accelerate its end-effector, as well as to apply forces/moments to the environment at the end-effector. This work considers velocity forces, including Coriolis forces, and the reduction of actuator torque with rotor velocity described by the speed-torque curve, at a particular configuration of a manipulator. The focus here is on nonredundant manipulators with as many actuators as degrees-of-freedom. Analysis of the velocity forces is accomplished using optimization techniques, where the optimization problem consists of an objective function and constraints which are all purely quadratic forms, yielding a nonconvex problem. Dialytic elimination is used to find the globally optimal solution to this problem. The proposed method does not use iterative numerical optimization methods. The PUMA 560 manipulator is used as an example to illustrate this methodology. The methodology provides an analytical analysis of the velocity forces which insures that the globally optimal solution to the associated optimization problem is found.
Integrating Target Costing Into Perception-Based Concept Evaluation of Complex and Large-Scale Systems Using Simultaneously Decomposed QFD
Authors: Takai Shun , Ishii Kosuke
Published: November 2006

In the conceptual design phase, engineers may need to perceptually screen and prioritize feasible design concepts by their potential to fulfill both customer and financial requirements. This paper presents a system design methodology that integrates perception-based concept evaluation and target costing of complex and large-scale systems. The methodology decomposes a system into modules and evaluates each module concept with its target requirements and cost. This method proposes the decomposition of quality function deployment matrices simultaneously for both requirements and structure in order to allocate the worth and target cost of the modules in a system. Developed from module concepts that satisfy their target requirements and cost, this new system should better satisfy both customer and financial requirements.
Application of Matroid Method in Kinematic Analysis of Parallel Axes Epicyclic Gear Trains
Authors: Talpasanu Ilie , Yih T. C. , Simionescu P. A.
Published: November 2006

A novel method for kinematic analysis of parallel-axes epicyclic gear trains is presented, called the incidence and transfer method, which uses the incidence matrices associated with the edge-oriented graph associated to the mechanism and the transfer joints (teeth contact joints). Relative to such joints, a set of independent equations can be generated for calculating the angular positions, velocities, and accelerations. Complete kinematic equations are obtained in matrix form using a base of circuits from a cycle matroid. The analysis uses the relationships between the number of mobile links, number of joints, and number of circuits in the base of circuits, together with the Latin matrix (whose entries are function of the absolute values of the partial gear ratios of the transmission). Calculating the rank of the Latin matrix can identify singularities, like groups of gears that rotate as a whole. Relationships between the output and input angular velocities and accelerations are then determined in a matrix-based approach without using any derivative operations. The proposed method has general applicability and can be employed for systems with any number of gears and degrees of freedom, as illustrated by the numerical examples presented.
Failure Surface Frontier for Reliability Assessment on Expensive Performance Function
Authors: Shan Songqing , Wang G. Gary
Published: November 2006

This work proposes a novel concept of failure surface frontier (FSF), which is a hyper-surface consisting of the set of non-dominated failure points on the limit states of a failure region. Assumptions, definitions, and benefits of FSF are described first in detail. It is believed that FSF better represents the limit states for reliability assessment (RA) than conventional linear or quadratic approximations on the most probable point. Then, a discriminative sampling based algorithm is proposed to identify FSF, based on which the reliability can be directly assessed for expensive performance functions. Though an approximation model is employed to approximate the limit states, it is only used as a guide for sampling and a supplementary tool for RA. Test results on well-known problems show that FSF-based RA on expensive performance functions achieves high accuracy and efficiency, when compared with the state-of-the-art results archived in literature. Moreover, the concept of FSF and proposed RA algorithm are proved to be applicable to problems of multiple failure regions, multiple most probable points, or failure regions of extremely small probability.
Production of Hydrogen With Low Carbon Monoxide Formation Via Catalytic Steam Reforming of Methanol
Authors: Patel Sanjay , Pant K. K.
Published: November 2006

The production of hydrogen was investigated in a fixed bed tubular reactor via steam reforming of methanol (SRM) using CuO∕ZnO∕Al2O3 catalysts prepared by wet impregnation method and characterized by measuring surface area, pore volume, x-ray diffraction patterns, and scanning electron microscopy photographs. The SRM was carried out at atmospheric pressure, temperature 493-573K, steam to methanol molar ratio 1–1.8 and contact-time (W/F) 3–15kg cat./(mol/s of methanol). Effects of reaction temperature, contact-time, steam to methanol molar ratio and zinc content of the catalyst on methanol conversion, selectivity, and product yields was evaluated. The addition of zinc enhanced the methanol conversion and hydrogen production. The excess steam promoted the methanol conversion and suppressed the carbon monoxide formation. Different strategies have been mentioned to minimize the carbon monoxide formation for the steam reforming of methanol to produce polymer electrolyte membrane (PEM) fuel cell grade hydrogen. Optimum operating conditions with appropriate composition of catalyst has been investigated to produce more selective hydrogen with minimum carbon monoxide. The experimental results were fitted well with the kinetic model available in literature.
Power Cycle Integration and Efficiency Increase of Molten Carbonate Fuel Cell Systems
Authors: Varbanov Petar , Klemeš Jiří , Shah Ramesh K. , Shihn Harmanjeet
Published: November 2006

A new view is presented on the concept of the combined cycle for power generation. Traditionally, the term “combined cycle” is associated with using a gas turbine in combination with steam turbines to better utilize the exergy potential of the burnt fuel. This concept can be broadened, however, to the utilization of any power-generating facility in combination with steam turbines, as long as this facility also provides a high-temperature waste heat. Such facilities are high temperature fuel cells. Fuel cells are especially advantageous for combined cycle applications since they feature a remarkably high efficiency—reaching an order of 45–50% and even close to 60%, compared to 30–35% for most gas turbines. The literature sources on combining fuel cells with gas and steam turbines clearly illustrate the potential to achieve high power and co-generation efficiencies. In the presented work, the extension to the concept of combined cycle is considered on the example of a molten carbonate fuel cell (MCFC) working under stationary conditions. An overview of the process for the MCFC is given, followed by the options for heat integration utilizing the waste heat for steam generation. The complete fuel cell combined cycle (FCCC) system is then analyzed to estimate the potential power cost levels that could be achieved. The results demonstrate that a properly designed FCCC system is capable of reaching significantly higher efficiency compared to the standalone fuel cell system. An important observation is that FCCC systems may result in economically competitive power production units, comparable with contemporary fossil power stations.
Development of Stabilized NiO Cathodes for Molten Carbonate Fuel Cell
Authors: Ryu B. H. , Jang I. G. , Moon K. H. , Han J. , Lim T.-H.
Published: November 2006

The stabilized NiO cathodes were fabricated by Li‐Co‐O coated Ni powder which was synthesized by hydrothermal treatment in 4-6MLiOH∙H2O. The morphology of Li‐Co‐O coating was characterized by spectroscopic techniques to investigate the optimal synthesis conditions such as temperature, reaction time, and reactant molarity. Li‐Co‐O coating was consisted of LiCoO2, Co(OH)2, and CoOOH, and the amount of LiCoO2 was increased with increasing time and molarity of LiOH∙H2O. The mechanical properties of the stabilized NiO cathodes were also measured to evaluate the stability in molten carbonate fuel cell (MCFC) applications. The bending strength of the stabilized cathode was significantly improved compared to the typical NiO cathode. The pores of the stabilized cathode showed typical bimodal distribution in size due to the micropores developed by coated materials, and the overall porosity was higher than 75% under optimal synthesis conditions, which is also promising for MCFC applications.
Dynamic Load and Temperature Behavior of a PEFC-Hybrid-System
Authors: Graf C. , Friedrich K. A. , Vath A. , Nicoloso N.
Published: November 2006

A dynamic model of a polymer electrolyte fuel cell hybrid system has been developed within MATLAB-SIMULINK. Components are modeled using electrochemical and mass transport as well as heat transfer equations. The implemented equations describe the steady-state as well as the dynamic operation of the system with sufficient accuracy, although considerable simplifications have been made for the stack and the peripheral components to keep model complexity and computing time low. Emphasis is given to the operation limits of the PEFC system, notably the conditions for trouble-free operation at different loads and high or low ambient temperature. The potential of the simulation as system optimization tool and efficient operation guide are demonstrated. Model validation was accomplished by experiments on a homemade 150W portable system including a Ni-MH accumulator for 300W peak power output.
Optimization and Economic Analysis of an Hybrid Fuel Cell, PhotoVoltaic and Battery Electric Power Generation System
Authors: Jemeï Samir , Hissel Daniel , Coince Anne-Sophie , Al-Nasrawi Boris
Published: November 2006

This paper presents a technical and economical study of a hybrid—fuel cell, photovoltaic, and battery—electric generation system. The system is installed on five different remote sites. These sites are family houses located in different regions in France beyond the reach of electrical power lines. The optimum system configuration is not often easily found and a lot of calculations and/or simulations are required in order to decide which combination gives the best technical and financial benefit. The aim of this study is to design each component of the remote generation system in order to get the best technical and financial combination. In this paper, a method is suggested to find the optimum combination for a hybrid power system dedicated to off-grid electricity users. Indeed, this project permits to save up to 25% of the initial cost.
Stable Single-Chamber Solid Oxide Fuel Cells Based on Doped Ceria Electrolytes and La0.5Sr0.5CoO3 as a New Cathode
Authors: Piñol Salvador
Published: November 2006

Several cathodes working in hydrocarbons diluted atmospheres have been proposed for single-chamber solid oxide fuel cells (SOFCs) fabrication. But, few cathodes work well in propane. In this work, we propose a new stable cathode of La0.5Sr0.5CoO3 (LSCO) for the single-chamber SOFCs, which works well in diluted propane atmospheres. For this purpose, powders of Ce0.8Gd0.2O1.9 (CGO) for electrolytes and powders of (LSCO) for cathodes were prepared by sol-gel related techniques as pentadionate methods. These methods consist of preparing a solution from the acetates or pentadionates followed by a jellification. Then, the decomposition of the organic molecules is initiated, obtaining nanometric powders of the abovementioned compounds. In this way, we have obtained high purity powders of CGO and LSCO as confirmed by x-ray diffraction powder analysis. Microstructure was analyzed by SEM and TEM microscopy, the analysis of the powders obtained by sol-gel techniques shows a nanometric size grain (∼30nm) and reactivity for sintering was studied in detail. Very high-density electrolytes (∼95-99% of theoretical density) were obtained with better power density currents than in samples prepared by solid-state reaction samples. Uniaxial pressing ceria based electrolytes were prepared from these powders and characterized in one chamber reactor using propane as fuel and LSCO+CGO as cathode. Anodes were prepared from Ni+CGO mixtures. Different gas mixtures of propane and air were prepared and tested at different flow rates in order to optimize electrical properties. Stable single-chamber fuel cells working in diluted propane atmospheres could be prepared with these materials.
A Feasibility Study of an Auxiliary Power Unit Based on a PEM Fuel Cell for On-Board Applications
Authors: Bagnoli Michele , Belvedere Bruno , Bianchi Michele , Borghetti Alberto , Pascale Andrea De , Paolone Mario
Published: November 2006

Proton exchange membrane (PEM) fuel cells show characteristics of high power density, low operating temperature, and fast start-up capability, which make them potentially suitable to replace conventional power sources (e.g., internal combustion engines) as auxiliary power units (APU) for on-board applications. This paper presents a methodology for a preliminary investigation on either sizing and operating management of the main components of an on-board power system composed by: (i) PEM fuel cell, (ii) hydrogen storage subsystem, (iii) battery, (iv) grid interface for the connection to an external electrical power source when available, and (v) electrical appliances and auxiliaries installed on the vehicle. A model able to reproduce the typical profiles of electric power requests of on-board appliances and auxiliaries has been implemented in a computer program. The proposed methodology helps also to define the sizing of the various system components and to identify the fuel cell operating sequence, on the basis of the above mentioned load profiles.