bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential modulation of interleukin 8 by interleukin 4 and interleukin 10 in HepG2 cells treated with acetaldehyde
Authors: Gómez‐Quiroz Luis Enrique , Paris Raquel , María Lluis José , Bucio Leticia , Souza Verónica , Hernández Elizabeth , Gutiérrez Mario , Santiago Mariana , García‐Ruiz Carmen , Fernández‐Checa José C. , Kershenobich David , Gutiérrez‐Ruiz Ma. Concepción
Published: February 2005

Abstract: Background/Aim: Pro‐inflammatory cytokines and chemokines, such as interleukin (IL) 8, are important mediators of hepatic injury and repair following an insult. The purpose of this work was to study the regulation of IL‐8 by IL‐10 and IL‐4 in HepG2 cells treated with acetaldehyde (Ac). Methods: HepG2 cells were pretreated with IL‐10 or IL‐4 before exposure to Ac, examining IL‐8 expression by reverse transcription polymerase chain reaction and Western blot.

Results: Ac treatment produced an increment in IL‐8 induction and secretion that was prevented by IL‐4 pretreatment, while IL‐10 pretreatment failed to decrease Ac‐induced IL‐8 production. Consistent with these findings Ac increased NF‐κB and AP‐1 activation that were prevented by IL‐4 but not by IL‐10, findings accompanied by greater IκB‐α levels in IL‐4 but not IL‐10 pretreated cells. In contrast to the pro‐inflammatory role of IL‐10 in HepG2, IL‐10 did not show any change in the activation of NF‐κB by Ac in WRL‐68 cells, a human fetal hepatic cell line. Moreover, IL‐10 did not induce the degradation of IκB‐α in cellular extract from rat primary cultured cells.

Conclusions: While the present findings demonstrate the anti‐inflammatory role of IL‐4 in preventing the expression of IL‐8 by Ac, the regulation of chemokines by anti‐inflammatory cytokines is complex and depends on the cellular lineage.
Hemosiderosis is associated with accelerated decompensation and decreased survival in patients with cirrhosis
Authors: Kayali Zeid , Ranguelov Rostislav , Mitros Frank , Shufelt Chrisandra , Elmi Farshad , Rayhill Stephen C. , Schmidt Warren N. , Brown Kyle E.
Published: February 2005

Abstract: Aim: Although hepatic iron deposition unrelated to hereditary hemochromatosis is commonly observed in cirrhosis, its clinical significance is unclear. The aim of this study was to examine the outcomes of cirrhotic patients with and without hemosiderosis.

Methods: Patients with an initial liver biopsy demonstrating cirrhosis between January 1993 and December 1997 were identified using the Department of Pathology database. Based on iron staining, patients were characterized as siderotic or nonsiderotic. Charts were reviewed to determine outcomes.

Results: Siderotic patients had significantly higher Child–Pugh (CP) and model for end‐stage liver disease (MELD) scores. Their median survival without transplant was 23 months vs. 85 months in the nonsiderotics (P<0.0001, confidence interval: 95%). On univariate analysis, siderosis was associated with a hazard ratio of 2.74 (P<0.0001). On multivariate analysis, the effect of siderosis was reduced but remained significant after correction for the CP or MELD score (hazard ratios 1.82 and 2.06, P=0.05 and 0.02, respectively). Child's A cirrhotics with hemosiderosis decompensated more rapidly and had shorter median survival than those without siderosis (P=0.007 and P=0.01, respectively).

Conclusions: The presence of siderosis is associated with more advanced liver dysfunction. Even when the effects of baseline liver function are taken into account, siderosis is associated with decreased survival and more rapid decompensation in cirrhosis.
Raloxifene improves bone mass in osteopenic women with primary biliary cirrhosis: results of a pilot study
Authors: Levy Cynthia , Harnois Denise M. , Angulo Paul , Jorgensen Roberta , Lindor Keith D.
Published: February 2005

Abstract: Background/Aims: Bone disease is common in patients with primary biliary cirrhosis (PBC). Our aim was to evaluate safety and efficacy of raloxifene in this population.

Methods: Nine postmenopausal women with PBC were enrolled and seven completed the study. Subjects received raloxifene 60 mg daily for 1 year. Each patient on raloxifene was age‐matched to three controls. Liver biochemistries were monitored periodically; bone mineral density (BMD) of the lumbar spine (LS) and femoral neck (FN) was measured at baseline and at 1 year.

Results: No significant adverse effects were reported. Liver biochemistries remained unchanged. Baseline LS‐BMD was similar in the treatment group and controls [median 0.720 g/cm2 (range 0.620–0.867) vs. 0.740 g/cm2 (0.570–1.040), P=0.5].

Conclusion: Compared with baseline, LS‐BMD improved significantly with 1 year of therapy [0.72 g/cm2 (0.62–0.87) vs. 0.74 g/cm2 (0.63–0.97), P=0.02]. FN‐BMD remained stable [0.53 g/cm2 (0.50–0.60) vs. 0.54 g/cm2 (0.49–0.63), P=0.6]. Improvement in LS BMD was seen in patients on raloxifene but not in matched controls [0.02 g/cm2 (0.01–0.10) vs. 0.00 g/cm2 (−0.120–0.040), P=0.06)]. In conclusion, raloxifene appears safe and of benefit in preventing bone loss in patients with PBC. Larger studies with longer follow‐up are warranted.
Combination of interferon‐β and angiotensin‐converting enzyme inhibitor, perindopril, attenuates the murine liver fibrosis development
Authors: Yoshiji Hitoshi , Kuriyama Shigeki , Noguchi Ryuichi , Yoshii Junichi , Ikenaka Yasuhide , Yanase Koji , Namisaki Tadashi , Kitade Mitsuteru , Yamazaki Masaharu , Tsujinoue Hirohisa , Fukui Hiroshi
Published: February 2005

Abstract:Recent studies have revealed that both interferon (IFN) and angiotensin‐converting enzyme inhibitor (ACE‐I) exert an anti‐fibrotic effect. The aim of this study was to examine the combined effect of the ACE‐I and IFN on the murine hepatic fibrosis development. A model of CCl4‐induced hepatic fibrosis was used to assess the effect of the clinically used ACE‐I, perindopril (PE), and IFN‐β. The PE and IFN were administered after 2‐week treatment with CCl4, and the hepatic indices of fibrosis were assessed at 8 weeks. Single treatment with either PE or IFN at the clinically available comparable doses significantly attenuated liver fibrogenesis associated with suppression of the hepatic hydroxyproline and serum fibrosis markers. The number of α‐smooth muscle actin‐positive cells, and the hepatic α1(I)‐procollagen mRNA were also markedly inhibited. The inhibitory effect of PE was more potent than IFN, and the combination treatment with PE and IFN almost completely attenuated liver fibrosis development.In vitro, the angiotensin‐II (AT‐II) type 1 receptor blocker and IFN suppressed the AT‐II‐induced proliferation and α1(I)‐procollagen mRNA expression of the activated hepatic stellate cells. The combination treatment of the clinically used PE and IFN may provide a new strategy for anti‐liver fibrosis therapy.
Hyperhomocysteinaemia in chronic liver diseases: role of disease stage, vitamin status and methylenetetrahydrofolate reductase genetics
Authors: Ventura Paolo , Rosa Maria Cristina , Abbati Gianluca , Marchini Stefano , Grandone Elvira , Vergura Patrizia , Tremosini Silvia , Zeneroli Maria Luisa
Published: February 2005

Abstract: Background/Aims: The liver plays a key role in sulphur aminoacid metabolism hence, homocysteine metabolism may be impaired in chronic liver diseases. The aim of this study was to investigate, in patients affected by chronic liver diseases, (1) the prevalence of hyperhomocysteinaemia and (2) the role of its determinants such as the stage and the aetiology of disease, vitamin status, genetic documented alterations (methylenetetrahydrofolate reductase deficiency) and presence/absence of documented malignant evolution (hepatocellular carcinoma).

Material and Methods: One hundred and thirty patients with chronic liver disease (34 with chronic active hepatitis, 12 with fatty liver and 88 with liver cirrhosis) and 50 healthy age‐matched control subjects were included into the study.

Results: Hyperhomocysteinaemia was defined as homocysteine plasma levels greater than 12.6 μmol/l. Hyperhomocysteinaemia prevalence in liver cirrhosis group was 40.9%, significantly higher (all P<0.01) with respect to controls (12%), chronic active hepatitis (14.7%) and fatty liver (25%) groups and increased with Child–Pugh stage [Child A: 22.2%, Child B (50%); Child C (58.3%)]. In chronic‐active hepatitis and liver cirrhosis, the prevalence of subjects with methylenetetrahydrofolate reductase C677→T mutation (both as CT and as TT) and hyperhomocysteinaemia results in significantly higher levels with respect to controls. Methylenetetrahydrofolate reductase C677→T mutation and disease stage showed to be the most important predictive factors of hyperhomocysteinaemia in liver cirrhosis whereas the influence of homocysteine‐related vitamin status seems to have a secondary role.

Conclusions: In conclusion hyperhomocysteinaemia is highly prevalent in liver cirrhosis but not in other chronic liver diseases; it may contribute to fibrogenesis and vascular complication of liver cirrhosis.
Early hepatitis C virus changes and sustained response in patients with chronic hepatitis C treated with peginterferon α‐2b and ribavirin
Authors: Gallegos‐Orozco J. F. , Loaeza‐del Castillo A. , Fuentes A. P. , García‐Sandoval M. , Soto L. , Rodríguez R. , Gutiérrez‐Ruíz M. C. , Gutiérrez‐Reyes G. , Bonder A. , Olivera M. A. , Kershenobich D.
Published: February 2005

Abstract: Background: Interferon‐based therapy induces changes in viral dynamics in chronic hepatitis C (CHC) patients.

Aims: The aim of this study was to assess early hepatitis C virus (HCV)‐RNA changes and evaluate its predictive value to achieve sustained viral response (SVR) in patients with CHC treated with peginterferon α‐2b weekly plus ribavirin daily for 48 weeks.

Methods: HCV‐RNA was measured at baseline, 48 h, 4, 12, 24 and 48 weeks of treatment and 24 weeks after treatment.

Results: Eighteen HCV genotype 1 patients were included (13 male, five female) with a mean age of 44.4±11.9 years. Nine patients achieved SVR (50%). Viral decline occurred as early as 48 h; the magnitude of decline was statistically different between both groups (P<0.01). Responders had a ≥1 log10 drop in HCV‐RNA at 48 h (positive predictive value (PPV) of 89% to achieve SVR) that persisted at week 4. By week 12, serum HCV‐RNA was undetectable (PPV 100%).

Conclusions: Our data indicate that peginterferon α‐2b plus ribavirin treatment produces significant changes in HCV dynamics that can be detected as early as 48 h after the first dose of peginterferon α‐2b and that these changes are useful in predicting response to therapy in CHC patients.
A STUDY OF THE SEXUAL REPRODUCTION AND DETERMINATION OF MATING TYPE OF GYMNODINIUM NOLLERI (DINOPHYCEAE) IN CULTURE1
Authors: Figueroa Rosa Isabel , Bravo Isabel
Published: February 2005

Sexual reproduction of Gymnodinium nolleri (Ellegaard & Moestrup 1999) was studied by intercrossing experiments in all combinations of six clonal strains and backcrossing of five clonal F1 offspring. The results indicated that the conjugation of G. nolleri responded to the existence of more than two sexual types (complex heterothallism) and that compatibility between progeny of one cyst (inbreeding) was the rule. Sexual fusion, planozygote formation and development, cyst formation, and germination and planomeiocyte division were followed using time‐lapse photography. This study revealed many similarities between the sexual stages and life cycle pattern of G. nolleri and the related G. catenatum and the existence under culture conditions of an alternative cycle between vegetative cells and zygotes without a hypnozygote stage. The fate of zygotes, division or encystment, was influenced by the nutritional status of the external medium. The division of G. nolleri planozygotes was promoted by high levels of external nutrients, whereas the maximum percentage of encystment was recorded when phosphates were reduced in the isolation medium. The division of zygotes might be different from both vegetative and planomeiocyte division because it resulted in two‐cell chains with the cells not oriented in parallel.
MOLECULAR AND PHYLOGENETIC CHARACTERIZATION OF PHORMIDIUM SPECIES (CYANOPROKARYOTA) USING THE CPCB‐IGS‐CPCA LOCUS1
Authors: Teneva Ivanka , Dzhambazov Balik , Mladenov Rumen , Schirmer Kristin
Published: February 2005

The accurate determination of species of Cyanoprokaryota/Cyanophyceae has many important applications. These include the assessment of risk with regard to blooms in water reservoirs as well as the identification of species capable of producing valuable bioactive compounds. Commonly, Cyanoprokaryota are classified based on their morphology. However, morphological criteria are not always reliable because they may change, for example, due to environmental factors. Thus, genetic and molecular analyses are a promising additional approach, but their application has so far been limited to relatively few genera. In light of this, we present here the first characterization of species and strains of the genus Phormidium Kütz. based on the cpcB‐IGS‐cpcA locus of the phycocyanin operon. In phylogenetic analyses using deduced amino acid sequences of the cpcB‐cpcA regions, Phormidium was found to be polyphyletic. This analysis appeared to be dominated by the cpcB region, which is characterized by a relatively high percentage of informative substitutions. The percentage of variable positions within the cpcB‐IGS‐cpcA locus overall was 16.5%, thereby indicating a level of divergence remarkably higher than that reported for Nodularia and Arthrospira in previous studies relying on cpcB‐IGS‐cpcA. Further, alignment of informative nucleotide substitutions in the cpcB‐IGS‐cpcA sequences revealed a mosaic distribution, which may be indicative of genetic recombination events. Finally, the length and sequences of the IGS region alone proved useful as markers to differentiate the cyanobacterial genus Phormidium. However, whether the IGS region per se is sufficiently discriminatory to differentiate between Phormidium species or even strains requires further investigation using newly identified Phormidium sequence data.
DIVERSITY IN THE GENUS SKELETONEMA (BACILLARIOPHYCEAE). II. AN ASSESSMENT OF THE TAXONOMY OF S. COSTATUM‐LIKE SPECIES WITH THE DESCRIPTION OF FOUR NEW SPECIES1
Authors: Sarno Diana , Kooistra Wiebe H. C. F. , Medlin Linda K. , Percopo Isabella , Zingone Adriana
Published: February 2005

The morphology of strains of Skeletonema Greville emend Sarno et Zingone was examined in LM, TEM, and SEM and compared with sequence data from nuclear small subunit rDNA and partial large subunit rDNA. Eight distinct entities were identified, of which four were known: S. menzelii Guillard, Carpenter et Reimann; S. pseudocostatum Medlin emend. Zingone et Sarno; S. subsalsum (Cleve) Bethge; and S. tropicum Cleve. The other four species were new: S. dohrnii Sarno et Kooistra sp. nov., S. grethae Zingone et Sarno sp. nov., S. japonicum Zingone et Sarno sp. nov., and S. marinoi Sarno et Zingone sp. nov. Skeletonema species fell into four morphologically distinct groups corresponding to four lineages in the small subunit and large subunit trees. Lineage I included S. pseudocostatum, S. tropicum, S. grethae, and S. japonicum. All have external processes of the fultoportulae with narrow tips that connect with those of sibling cells via fork‐, knot‐, or knuckle‐ like junctions. Lineage II included only the solitary species S. menzelii. Lineage III comprised S. dohrnii and S. marinoi. This latter pair have flattened and flared extremities of the processes of the fultoportulae, which interdigitate with those of contiguous valves without forming knots or knuckles. Lineage IV only contained the brackish water species S. subsalsum. Some species also differ in their distribution and seasonal occurrence. These findings challenge the concept of S. costatum as a single cosmopolitan and opportunistic species and calls for reinterpretation of the vast body of research data based on this species.
EFFECT OF SALINITY ON PSEUDO‐NITZSCHIA SPECIES (BACILLARIOPHYCEAE) GROWTH AND DISTRIBUTION1
Authors: Thessen Anne E. , Dortch Quay , Parsons Michael L. , Morrison Wendy
Published: February 2005

Salinity varies widely in coastal areas that often have a high abundance of Pseudo‐nitzschia H. Peragallo. Pseudo‐nitzschia is abundant in Louisiana waters, and high cellular domoic acid has been observed in natural samples but no human illness has been reported. To assess the threat of amnesic shellfish poisoning (ASP), we examined the effect of salinity on Pseudo‐nitzschia occurrence in the field and growth in the laboratory with special emphasis on the salinity range where oysters are harvested (10–20 psu). In Louisiana coastal waters, Pseudo‐nitzschia spp. occurred over a salinity range of 1 to >35 psu, but they occurred more frequently at higher rather than lower salinities. Seven species were identified, including toxigenic species occurring at low salinities. In culture studies, seven clones of three species grew over a salinity range of 15 to 40 psu, some grew at salinities down to 6.25 psu, and most grew at salinities up to 45 psu. Tolerance of low salinities decreased from Pseudo‐nitzschia delicatissima (Cleve) Heiden to P. multiseries (Hasle) Hasle to P. pseudodelicatissima (Hasle) Hasle emend. Lundholm, Hasle et Moestrup. In conclusion, although Pseudo‐nitzschia was more prevalent in the field and grew better in the laboratory at higher salinities, it grew and has been observed at low salinities. Therefore, the probability of ASP from consumption of oysters harvested from the low salinity estuaries of the northern Gulf of Mexico is low but not zero; animal mortality events from toxin vectors other than oysters at higher salinity on the shelf are more likely.
TAXONOMIC REEXAMINATION OF 17 SPECIES OFNITELLASUBGENUSTIEFFALLENIA(CHARALES, CHAROPHYCEAE) BASED ON INTERNAL MORPHOLOGY OF THE OOSPORE WALL AND MULTIPLE DNA MARKER SEQUENCES1
Authors: Sakayama Hidetoshi , Miyaji Kazuyuki , Nagumo Tamotsu , Kato Masahiro , Hara Yoshiaki , Nozaki Hisayoshi
Published: February 2005

In an attempt to reconstruct the natural taxonomic system forNitella, 17 species ofNitellasubgenusTieffalleniawere reexamined using SEM observations of the internal morphology of the oospore wall (IMOW) and phylogenetic analyses of 4553 base pairs from multiple DNA markers (atpB,rbcL,psaB, and ITS‐5.8S rRNA genes). Our SEM observations identified three types of IMOW: homogeneous (HG), weakly spongy (W‐SG), and strongly spongy (S‐SG) types. Based on differences in the IMOW, species with reticulate or tuberculate oospore wall ornamentation in the external morphology of the oospore wall (EMOW) were subdivided into two distinct groups (characterized by the HG or S‐SG types of IMOW, respectively), which were robustly separated from each other in our molecular phylogenetic analyses. In our molecular phylogeny, the subgenusTieffalleniaconsisted of four robust monophyletic groups—three clades of the HG type and a spongy (S‐SG and W‐SG) type clade—that were characterized by differences in the IMOW and EMOW. In addition, our SEM observations and sequence data verified the distinct status of five species (N.japonicaAllen,N.oligospiraA. Braun,N.vieillardiistat. nov.,N.imperialisstat. nov., andN.morongiiAllen) that R. D. Wood had assigned as infraspecific taxa. Moreover, our SEM observations of the IMOW also suggested thatN.megaspora(J. Groves) Sakayama originally identified by LM includes at least two distinct species, characterized by W‐SG and S‐SG types of IMOW, respectively.
Influences of flame configurations on flame properties and NO emissions in combustion with high‐temperature air
Authors: Yang Weihong , Mörtberg Magnus , Blasiak Wlodzimierz
Published: February 2005

High‐temperature air combustion using the high‐cycle generator is attracting great interest in mettalurgical industries. Flame configurations play a very important role when a modern regenerative burner system is adopted in an industrial furnace because multi‐burners are required. Numerical studies of combustion in a semi‐industrial scale test furnace equipped with two sets of two‐flame high‐cycle regenerative system have been performed and results were compared with experimental values. Influences of flame configurations on combustion properties and NO emissions of LPG with high‐temperature air were numerical studies as well as excess air ratio. The flame volume and size were figured out by a parameter named as oxidation mixture ratio. It is found that the flame configurations have strong influences on the combustion and flame properties as well as NO emission. Increasing the excess air ratio leads to increasing of NO emission. Lesser the ratio of fuel/air injection momentum larger is the NO production.
Solidification microstructure and heterogeneous nucleation phenomena in cast SiCp‐reinforced hypereutectic Al–Si alloy composites
Authors: Skolianos Stefanos M. , Mavropoulos Azarias A.
Published: February 2005

The microstructure and heterogeneous nucleation phenomena in cast SiCp‐reinforced hypereutectic Al–Si/alloy composites have been studied. Composite specimens were prepared using the compocasting technique and followed by remelting at 1023 K. The microstructure evolution of the composite has been investigated by water quenching the composite specimens at different stages of solidification. It has been observed that SiC particles can serve as substrate for the primary Si particles but not for α‐Al dendrites. Instead primary α‐Al dendrites push SiC particles into the last solidified liquid.

In the presence of SiC particles, the eutectic silicon morphology changes from plate and needle shape of the unreinforced alloy to just plate shape. Globularisation of primary α‐Al dendrites occurs at the eutectic temperature while primary Si crystals tend to agglomerate as solidification proceeds. As a result both the average size and the average volume fraction of the primary Si crystals increases. A significant refinement in the size of eutectic silicon can also be observed but only in the regions where SiC particles are present.
Process model of inclusion separation in a stirred steel ladle
Authors: Hallberg M. , Jönsson P. G. , Jonsson T. L. I. , Eriksson R.
Published: February 2005

A mathematical model, which can be used as a process model in production, was developed to predict total oxygen content and size distribution of non‐metallic inclusions in an agitated steel melt. Using a given pre‐deoxidation total‐oxygen‐content value and calculated velocity and turbulence data (induction or gas stirring), model output can be generated as a function of stirring time. Predicted initial inclusion size distributions were in good agreement with inclusion size distributions quantitatively determined by light optical microscopy and classification according to the Swedish standard SS 11 11 16. Results from simulations carried out for the two types of stirring indicated that the model can predict total oxygen content and inclusion size distribution as a function of time for induction and gas stirring in an acceptable way.
Dry comminution and liberation with microwave assistance
Authors: Wang Yanmin , Forssberg Eric
Published: February 2005

This paper presents the experimental results obtained from microwave‐assisted comminution/liberation tests on various minerals. The effects of microwave energy intensity and exposure time on microwave heating behaviour and grind‐ability of materials are discussed. The experimental results indicated that particle size has a significant effect. The coarser particles (−9.50 + 4.75 mm) of some minerals (limestone and quartz) were affected by microwave heating to varying degrees, resulting in an increased fineness of the ground product in a subsequent dry ball milling. It was observed that the silicate and carbonate minerals are difficult to heat at lower microwave energy intensities (<7 kW) during a short exposure (<30 min) due to their principally transparent or reflection to microwave energy. The thermal stress fractures in a copper ore in microwave exposure occurred readily, resulting in a better and cleaner liberation of sulphide minerals from the ore matrix.
FATTY ACID, TOCOPHEROL AND STEROL COMPOSITION AS WELL AS OXIDATIVE STABILITY OF THREE UNUSUAL SUDANESE OILS
Authors: MARIOD ABDALBASIT , MATTHÄUS BERTRAND , EICHNER K.
Published: February 2005

Three unusual oils, obtained from Sclerocarya birrea (Marula), Aspongopus viduatus (melon bug) and Agonoscelis pubescens (sorghum bug), collected in Sudan from Abu Gibaiha, Ghibaish and Rahad agricultural areas, respectively, were investigated. In addition to the oil content, the fatty acid as well as sterol composition was determined by capillary gas chromatography and the tocopherols were evaluated by high‐performance liquid chromatography. Oxidative stability of the oils was investigated by the Rancimat method. The oil content of seeds from S. birrea amounted to 53.5%, whereas bugs of A. viduatus and A. pubescens came to 45 and 60%, respectively. The oils contained 67.2, 46.5 and 40.9% oleic acid, 5.9, 3.4 and 34.5% linoleic acid, 14.1, 44.2 and 12.1% palmitic acid and traces of linolenic acid, respectively. The tocopherol content of these oils amounted to 13.7, 0.3 and 34.0 mg/100 g oil, respectively. Gamma‐tocopherol was the predominant tocopherol in the oil of S. birrea and A. pubescens. The total content of sterols in the three oils was 287, 17 and 450 mg/100 g oil, respectively, whereas β‐sitosterol was determined as the main compound in all oils with about 60% of the total sterols. In the oil of S. birrea higher amounts of 5‐avenasterol (4.8 mg/100 g) were found. The oxidative stability of the oils, as measured by the Rancimat test at 120C, was 43, 38 and 5.1 h, respectively.
GROUND MEAT BROWNING/DRAINING EFFECTS ON FATTY ACID PROFILES
Authors: RHEE KI SOON , ZIPRIN YOLANDA A.
Published: February 2005

Recipes using ground meat as a major ingredient often suggest browning the meat and draining the cookout before adding other ingredients. When such brown‐and‐drain process was evaluated on ground pork with 10%, 20% and 30% fat and ground beef with 10% and 20% fat, retention percentages of saturated, monounsaturated and polyunsaturated fatty acids decreased with increasing initial fat levels. However, the amounts of fatty acids in the browned‐and‐drained meat from a given amount of raw meat were still higher for samples with higher initial fat levels, regardless of the fatty acid class. At the fat level of 10%, retention of each class of fatty acids was less for ground pork than for ground beef, whereas the opposite was observed at 20% fat. Particle size of the raw meat had little effect on fatty acid profiles of the browned‐drained meat and fat drip and the retention of individual fatty acids.
RIE-Texturing of Industrial Multicrystalline Silicon Solar Cells
Authors: Ruby Douglas S. , Zaidi Saleem , Narayanan S. , Yamanaka Satoshi , Balanga Ruben
Published: February 2005

We developed a maskless plasma texturing technique for multicrystalline Si (mc-Si) cells using Reactive Ion Etching (RIE) that results in higher cell performance than that of standard untextured cells. Elimination of plasma damage has been achieved while keeping front reflectance to low levels. Internal quantum efficiencies higher than those on planar and wet-textured cells have been obtained, boosting cell currents and efficiencies by up to 6% on tricrystalline Si cells.
Third Body Influence on Thermal Friction Contact Problems: Application to Braking
Authors: Majcherczak Didier , Dufre´noy Philippe , Nai¨t-Abdelaziz Moussa
Published: February 2005

The aim of this study is to evaluate the temperature and the heat distribution into the two components of a disc brake system by combining macroscopic and microscopic effects. The major difficulty of the thermal problem is to determine how the heat is generated and how it is distributed in the two components in contact during transient state. Contrary to classical approaches assuming equal temperature at the contact surfaces, a contact interface is introduced in the model as a thin layer of third body with uniform volumic heat generation. This micro-macro model gives original indications on the temperatures near the contact surfaces, on the thermal gradients between the two components and on the heat partition between the two bodies during the braking time. Comparison with classical thermal models is discussed.
Radiative Heat Transfer Across Glass Coated With Gold Nano-Particles
Authors: Chowdhury Humayer , Xu Xiaoda , Huynh Phuoc , Cortie Michael B.
Published: February 2005

Solar glazing based on reflective or absorptive coatings of noble metals or dielectric compounds respectively is well-known. However, the use of gold nano-particles in an absorptive role has hardly been considered. The performance of such coatings was assessed using an array of incandescent lamps as radiation source, and the results ranked against commercial glazing systems. The nanoparticle coatings attenuated the radiation by 40%. An additional 15% of the incoming energy was convected off the inside surface of the glass. The neutral color and simple manufacture of the coatings suggests that they might have applications on architectural glass.
Modeling and Experimental Evaluation of Passive Heat Sinks for Miniature High-Flux Photovoltaic Concentrators
Authors: Sun Jian , Israeli Tomer , Reddy T. Agami , Scoles Kevin , Gordon Jeffrey M. , Feuermann Daniel
Published: February 2005

An important consideration in the practical realization of high-concentration photovoltaic devices is the heat rejection at high power densities to the environment. Recently, optical designs for generating solar flux in excess of 1000 suns on advanced solar cells–while respecting flux homogeneity and system compactness–were suggested with the introduction of solar fiber-optic mini-dish concentrators, tailored specifically to high-flux photovoltaic devices [1]. At the core of the design is the miniaturization of the smallest building block in the system–the concentrator and the cell–permitting low-cost mass production and reliance on passive heat rejection of solar energy that is not converted to electricity. First, this paper proposes a relatively simple 1-D axi-symmetric model for predicting the thermal and electrical performance of such mini-dish high-flux concentrators. Experimental measurements were performed with a real-sun solar simulator, indoors under controllable conditions, at flux levels up to 5,000 suns. A CFD (Computational Fluid Dynamics) model was also developed for model-validation. Both the modeling approaches predict heat sink temperatures within experimental uncertainty of a couple of degrees. Next, the 1-D axi-symmetric model is used to evaluate the sensitivity of different solar cell model assumptions, environmental effects (such as outdoor temperature, and the wind speed), heat sink size and geometry, thermal contact resistance, etc. It was confirmed that the miniaturization of the solar cell module permits passive heat rejection, such that solar cell temperatures should not reach more than 80 °C at peak insolation and stagnation conditions. Though the cell rated efficiency degrades by only 1-2% in absolute terms, higher cell temperatures may compromise the integrity of the cell circuitry and of the encapsulation. The 1-D axi-symmetric model also allows optimization of the heat sink geometric dimensions for a given volume. Hour-by-hour performance simulation results for such an optimized design configuration were performed for one month in summer and one month in winter for two locations namely Philadelphia, PA and Phoenix, AZ. The insight gained from this study is important for the proper design of the various components and materials to be used in PV mini-dishes. Equally important is that it allows similar types of analyses to be performed and well-informed design choices to be made for mini-dishes that have to operate under different climatic conditions with cells of different performance and concentration ratios.© 2005 American Institute of Physics.
Design of Commercial Solar Updraft Tower Systems—Utilization of Solar Induced Convective Flows for Power Generation
Authors: Schlaich Jo¨rg , Bergermann Rudolf , Schiel Wolfgang , Weinrebe Gerhard
Published: February 2005

A solar updraft tower power plant—sometimes also called “solar chimney” or just “solar tower”—is a solar thermal power plant utilizing a combination of solar air collector and central updraft tube to generate a solar induced convective flow which drives pressure staged turbines to generate electricity. The paper presents theory, practical experience, and economy of solar updraft towers: First a simplified theory of the solar tower is described. Then results from designing, building and operating a small scale prototype in Spain are presented. Eventually technical issues and basic economic data for future commercial solar tower systems like the one being planned for Australia are discussed.
The Carbon Content of Hydrogen Vehicle Fuel Produced by Hydrogen Electrolysis
Authors: Stavy Michael
Published: February 2005

This paper discusses the four points in the Kreith and Isler August, 2002 Journal of Solar Energy Engineering Discussion Note, “Comments Dealing with Fuel Cell Energy Policy and Renewable Energy”. The paper compares the carbon emissions (gm-CO2/mi) of the current US passenger gasoline vehicle (GV) fleet with a proposed US passenger hydrogen vehicle (HV) fleet. The paper uses the efficiency method to compute the carbon content (gm-CO2/gal-H2) of hydrogen vehicle fuel (HVF) produced by a hydrogen electrolyzer (HE). The carbon content of the electricity (gm-CO2/kWh) used to power a HE is used to compute the carbon content of the HVF. The fuel efficiency (mpg) of the current US GV fleet and of the proposed HV fleet are used to compute the carbon emissions of the two fleets. The four points of Kreith and Isler are demonstrated for H2 from a HE. Equations and a list of abbreviations are provided.
The Tracking of the Sun for Solar Paraboloidal Dish Concentrators
Authors: Shanmugam S. , Christraj W.
Published: February 2005

Paraboloidal dish concentrators need tracking the sun in the east-west and north-south direction continuously throughout the year. But this paper explains the method of intermittent tracking of the sun in the north-south direction with no tracking in the east-west direction for less energy yield. The frequency of tracking in the north-south direction is determined by the relationship between the variation in solar altitude angle and the size of the absorber in the Paraboloidal dish concentrator. A computer program in Visual BASIC is written to enable the detailed calculations of data for the analysis.© 2004 American Institute of Physics.
Testing of Thermocline Filler Materials and Molten-Salt Heat Transfer Fluids for Thermal Energy Storage Systems in Parabolic Trough Power Plants
Authors: Brosseau Doug , Kelton John W. , Ray Daniel , Edgar Mike , Chisman Kye , Emms Blaine
Published: February 2005

Parabolic trough power systems that utilize concentrated solar energy to generate electricity are a proven technology. Industry and laboratory research efforts are now focusing on integration of thermal energy storage as a viable means to enhance dispatchability of concentrated solar energy. One option to significantly reduce costs is to use thermocline storage systems, low-cost filler materials as the primary thermal storage medium, and molten nitrate salts as the direct heat transfer fluid. Prior thermocline evaluations and thermal cycling tests at the Sandia National Laboratories’ National Solar Thermal Test Facility identified quartzite rock and silica sand as potential filler materials. An expanded series of isothermal and thermal cycling experiments were planned and implemented to extend those studies in order to demonstrate the durability of these filler materials in molten nitrate salts over a range of operating temperatures for extended time frames. Upon test completion, careful analyses of filler material samples, as well as the molten salt, were conducted to assess long-term durability and degradation mechanisms in these test conditions. Analysis results demonstrate that the quartzite rock and silica sand appear able to withstand the molten salt environment quite well. No significant deterioration that would impact the performance or operability of a thermocline thermal energy storage system was evident. Therefore, additional studies of the thermocline concept can continue armed with confidence that appropriate filler materials have been identified for the intended application.
Two-Dimensional Axi-Symmetric Model of a Solar-Thermal Fluid-Wall Aerosol Flow Reactor
Authors: Dahl Jaimee K. , Weimer Alan W. , Z’Graggen Andreas , Steinfeld Aldo
Published: February 2005

A solar-thermal fluid-wall reactor consisting of three concentric vertical tubes is constructed to dissociate methane to hydrogen and carbon black using concentrated solar power. Several aspects of the design are modeled for scaling the system up: the heat transfer and its effect on the integrity of the materials, and the fluid flow of all gas streams within the reactor. It is determined that the inlet gas temperatures, mass flow rates, and permeability of the porous wall affect the gas flow profile through the porous tube wall. By increasing the inlet gas temperature and/or the tube permeability in the hot zone section of the reactor, a more uniform flow profile can be obtained along the length of the tube.
Surface Temperature in Oscillating Sliding Interfaces
Authors: Mansouri M. , Khonsari M. M.
Published: February 2005

A model is developed to predict the behavior of two sliding bodies undergoing oscillatory motion. A set of four dimensionless groups is introduced to characterize the transient dimensionless surface temperature rise. They are: the Peclet number Pe, the Biot number Bi, the amplitude of oscillation A, and the Hertzian semi-contact width α. Also considered in the analysis is the effect of the ratio β=A/α of the amplitude to the semi-contact width. The results of a series of simulations, covering a range of these independent parameters, are presented, and examples are provided to illuminate the utility of the model.
A Material Removal Rate Model Considering Interfacial Micro-Contact Wear Behavior for Chemical Mechanical Polishing
Authors: Jeng Yeau-Ren , Huang Pay-Yau
Published: February 2005

Chemical Mechanical Polishing (CMP) is a highly effective technique for planarizing wafer surfaces. Consequently, considerable research has been conducted into its associated material removal mechanisms. The present study proposes a CMP material removal rate model based upon a micro-contact model which considers the effects of the abrasive particles located between the polishing interfaces, thereby the down force applied on the wafer is carried both by the deformation of the polishing pad asperities and by the penetration of the abrasive particles. It is shown that the current theoretical results are in good agreement with the experimental data published previously. In addition to such operational parameters as the applied down force, the present study also considers consumable parameters rarely investigated by previous models based on the Preston equation, including wafer surface hardness, slurry particle size, and slurry concentration. This study also provides physical insights into the interfacial phenomena not discussed by previous models, which ignored the effects of abrasive particles between the polishing interfaces during force balancing.
State of the Art in Laser Surface Texturing
Authors: Etsion Izhak
Published: February 2005

Surface texturing has emerged in the last decade as a viable option of surface engineering resulting in significant improvement in load capacity, wear resistance, friction coefficient etc. of tribological mechanical components. Various techniques can be employed for surface texturing but Laser Surface Texturing (LST) is probably the most advanced so far. LST produces a very large number of micro-dimples on the surface and each of these micro-dimples can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication, a micro-reservoir for lubricant in cases of starved lubrication conditions, or a micro-trap for wear debris in either lubricated or dry sliding. The present paper reviews the current effort being made world wide on surface texturing in general and on laser surface texturing in particular. It presents the state of the art in LST and the potential of this technology in various lubricated applications like mechanical seals, piston rings and thrust bearings. The paper also describes some fundamental on going research around the world with LST.
Dynamic Characteristics of Sealed Squeeze Film Damper With a Central Feeding Groove
Authors: Kim Keun-Joo , Lee Chong-Won
Published: February 2005

In this paper, the dynamic characteristics of an oil-lubricated, sealed squeeze film damper (SFD) with a central feeding groove are analytically derived based on an enhanced dynamic pressure field analysis, accounting for the effect of the seal and feeding grooves, and its validity is experimentally verified. A test rig using an active magnetic bearing system as an exciter is introduced to identify the dynamic characteristics of SFDs with high accuracy and efficiency. Experiments are conducted with the seal gap varied, in order to investigate its effect on the dynamic characteristics of the SFD. The estimated and analytical damping and inertia coefficients for the sealed SFD with a groove are compared and it is found that the pressure field analysis, when neglecting the effect of the seal groove, tends to far underestimate the SFD dynamic coefficients.
Simulation of Wear Through Mass Balance in a Dry Contact
Authors: Fillot Nicolas , Iordanoff Ivan , Berthier Yves
Published: February 2005

Numerical investigations are carried out to simulate wear and the analysis of these simulations leads to proposing an original new wear law that takes into account interfacial particles in the contact. A 3D Discrete Element Model is presented that simulates the detachment of particles, their flow in the contact and their ejection. It shows that a layer of detached particles can be formed at the interface, separating the solids in contact. The simulations show how influential the contact geometry and the properties of the interfacial particles are in studying wear. The processes of material degradation and particle ejection are then studied separately. Their physical behavior is analyzed and simple analytical expressions are proposed. Consideration of the mass balance of the contact provides an analytical law for wear, involving the fate of the detached particles. Classical wear laws (such as Archard’s law), assuming that no particle stays in the contact, appear to be a limit case of this model.
Numerical Analysis of a Coupled Porous Journal and Thrust Bearing System
Authors: Kobayashi Takuji , Yabe Hiroshi
Published: February 2005

A numerical model has been developed to analyze both static and dynamic characteristics of a coupled porous journal and thrust bearing system that is used to support a rotating shaft in a magnetic hard disk drive. The analyzed system is composed of a porous sleeve, a herringbone-grooved solid thrust plate and a flanged shaft, where the bottom end is closed to form a cantilever spindle. The inner surface and the bottom face of the porous sleeve operate as a herringbone-grooved journal and thrust bearing, respectively. The model is based on the narrow groove theory for the bearing oil film, and Darcy’s law for the internal flow in the porous sleeve. The pressure distribution, static equilibrium position of the shaft and dynamic coefficients are obtained under a given external axial load. There exists a window of permeability of the porous sleeve that presents significant advantage to prevent the creation of a sub-ambient condition and to maintain a large thrust bearing film thickness at the expense of some loss of dynamic performance.
A Modified Turbulence Model for Low Reynolds Numbers: Application to Hydrostatic Seals
Authors: Brunetie`re Noe¨l
Published: February 2005

A modification of the Elrod and Ng turbulence model is presented. The order of magnitude of the Reynolds number in thin lubricant films varies between 102 and 105. For Reynolds numbers higher than 103, the fluid flow becomes turbulent. It is well accepted in lubrication to use a zero-equation turbulence model of the type developed by Constantinescu (1962, ASME J. Basic Eng., 84(1), pp. 139–151), Ng (1964, ASLE Trans., 7, pp. 311–321), Ng and Pan (1965, ASME J. Basic Eng., 87, pp. 675–688), Elrod and Ng (1967, ASME J. Lubr. Technol., 89, pp. 346–362), or Hirs (1973, ASME J. Lubr. Technol., 95, pp. 137–146). The Elrod and Ng approach is certainly the most efficient for combined pressure and shear flows where the Reynolds number is above 104. This paper proposes a modification of the Elrod and Ng model in order to ensure a good correlation with experimental data obtained with low Reynolds number turbulent flows. The present model, coupled with a scaling factor for taking into account the transition to turbulence, is therefore accurate for all of the typical Reynolds number values recorded in lubrication. The model is then applied to hydrostatic noncontacting face seals, which usually operate at Reynolds numbers varying from 103 to 104. The accuracy of the model is shown for this particular application of radial rotating flow. A special study is made of the transition to turbulence. The results are compared with those obtained using the initial Elrod and Ng model. The axial stiffness coefficient and the stability threshold are significantly affected by the turbulence model.
Non-Newtonian Thermal Analyses of Point EHL Contacts Using the Eyring Model
Authors: Liu Xiaoling , Jiang Ming , Yang Peiran , Kaneta Motohiro
Published: February 2005

A non-Newtonian numerical solution system for the thermal elastohydrodynamic lubrication (EHL) problems in point contacts has been developed. The Eyring rheology model has been used to describe the non-Newtonian flow of the lubricant. An effective viscosity has been defined for the Eyring fluid. The Newtonian solver can be applied easily to the non-Newtonian problems when the viscosity of the Newtonian fluid is replaced by the effective viscosity. A novel technique for the determination of the effective viscosity is proposed. Numerical solutions for the conventional point contact and normally crossing cylinders contact problems are presented and the effects of the entraining velocity, the load, the slide-roll ratio, and the characteristic shear stress of the Eyring fluid on the lubricating performance are discussed. The results indicate that the non-Newtonian thermal EHL theory predicts more realistic film temperatures and traction coefficients.
Wear Analysis of Head-Disk Interface During Contact
Authors: Peng Wei , Kiely James , Hsia Yiao-Tee
Published: February 2005

To achieve a higher storage density in a hard disk drive, the fly height of the air bearing slider, as part of the magnetic spacing, has to be minimized. At an ultralow fly height, the intermittent–continuous contact at the head–disk interface (HDI) is unavoidable and directly affects the mechanical and magnetic performance of the hard disk drive, and is of great interest. The HDI wear has a nonlinear and time-varying nature due to the change of contact force and roughness. To predict the HDI wear evolution, an iterative model of Coupled Head And Disk (CHAD) wear, is developed based on the contact mechanics. In this model, a composite transient wear coefficient is adopted and multiple phases of the wear evolution are established. A comprehensive contact stiffness is derived to characterize the contact at the HDI. The abrasive and adhesive wear is calculated based on the extended Archard’s wear law. The plastic and elastic contact areas are calculated with a three-dimensional (3D) sliding contact model. Based on the CHAD wear model, for the first time, the coupling between head and disk wear evolutions is thoroughly investigated. Accelerated wear tests have also been performed to verify the disk wear effect on the slider wear. A wear coefficient drop with time is observed during the tests and it is attributed to a wear mechanism shift from abrasive to adhesive wear. A shift in the type of contact from plastic to elastic accounts for the wear mechanism change.