bluuebunny/crossref_metadata_2025 huggingface dataset:
Dietary phytase increases the true absorption and endogenous fecal excretion of zinc in growing pigs given a corn‐soybean meal based diet
Authors: CHU Gyo‐Moon , KOMORI Motoharu , HATTORI Ryota , MATSUI Tohru
Published: October 2008

We investigated the effect of dietary phytase on the true absorption and endogenous fecal excretion of zinc (Zn) using 67Zn in growing pigs given a corn‐soybean meal based diet. Ten crossbred barrows were fed the control diet containing 90‐mg/kg Zn, 2.3‐g/kg phytate‐phosphorus and 3.7‐g/kg non‐phytate‐phosphorus or the phytase diet containing similar amounts of Zn and phytate‐phosphorus, and 1.4‐g/kg non‐phytate‐phosphorus with 750‐PU/kg phytase for 12 h/day. On day 6, the pigs were given 200 g of the corresponding diet labeled by 67Zn for 2 h. We measured feed intake, fecal Zn concentration and 67Zn abundance for the determination of apparent absorption, true absorption and endogenous fecal excretion of Zn. Although the apparent absorption of Zn did not significantly differ between the dietary groups, the phytase group had significantly more (P < 0.05) true absorption of Zn than the control group. The endogenous fecal excretion of Zn tended to be more (P = 0.07) in the phytase group than in the control group. These results suggest that dietary phytase improves Zn bioavailability through increasing the true absorption of Zn in growing pigs, which results in stimulating the endogenous fecal excretion of Zn when dietary Zn satisfies its requirement.
Characterization of bacteriocin produced by Streptococcus bovis J2 40‐2 isolated from traditional fermented milk ‘Dahi’
Authors: RASHID Harun‐ur , TOGO Kaname , UEDA Minoru , MIYAMOTO Taku
Published: October 2008

A bacteriocin‐producing strain Streptococcus bovis J2 40‐2 was isolated from traditional fermented milk ‘Dahi’ in Bangladesh. Despite its narrow antimicrobial spectrum, it showed strong antimicrobial activity against extremely challenging and problematic organisms in foods, such as Listeria monocytogenes. Bacteriocin was sensitive to several proteolytic enzymes and showed antimicrobial activity over a wide pH range of 2.0–10.0. It was stable when heated to 110°C for 20 min, but lost 25% of its activity when heated to 121°C for 15 or 20 min. Optimum bacteriocin production (5600 AU/mL) was achieved when the strain was cultured at 37°C for 24 h in MRS medium rather than in TYLG, GM17, or skim milk medium. Bacteriocin was partially purified by ammonium sulfate precipitation (80% saturation), dialysis (cut‐off MW: 3500) and gel filtration chromatography. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis revealed that bacteriocin had a molecular weight of approximately 4.5 kDa.
Effect of monomer treatment and polymerisation methods on the bond strength of resin teeth to denture base material
Authors: Barbosa Debora Barros , Monteiro Douglas Roberto , Barão Valentim Adelino Ricardo , Pero Ana Carolina , Compagnoni Marco Antonio
Published: October 2008

Background:  The fracture between acrylic denture base material and artificial teeth is a common clinical occurrence in dental prosthodontic practice.

Objective:  To evaluate the bond strength between acrylic resins and resin denture teeth when submitted by two protocols of monomer liquid application on the tooth surface and using different polymerisation methods.

Material and methods:  Microwave‐polymerised (Onda‐Cryl), heat‐polymerised (Clássico) and autopolymerising (Jet) acrylic resins and a brand of resin denture teeth (Biotone) were used. The acrylic resins were polymerised according to the cycles: (A) microwave – fast cycle, Onda‐Cryl; (B) microwave – long cycle, Onda‐Cryl; (C) microwave – manufacturer’s cycle, Onda‐Cryl; (T) water bath – long cycle, Clássico and (Q) bench polymerisation cycle, Jet. Thirty specimens were prepared for each polymerisation method; 10 were packed with acrylic resin after 60 s of monomer liquid application on the tooth surface, 10 after 180 s and 10 without any monomer liquid application. For the purpose of the study, a shear test was used. anova and Tukey tests were performed to identify significant differences (α = 0.05).

Results:  The highest bond strength values were found for monomer surface treatments, regardless of the polymerisation cycles. The highest significant values were found for cycles B (15.4 ± 1.8 MPa), C (11.9 ± 4.9 MPa) and T (15.4 ± 2.6 MPa) for non‐treated and 60 s methylmethacrylate treated groups. Comparing the monomer liquid treatment, they did not differ significantly (p > 0.05), except for cycle A (p < 0.05).

Conclusion:  Chemical treatment using monomer on the tooth surface prior to the acrylic resin packing improved the bond strength between resin denture tooth and acrylic resin, regardless of monomer liquid treatment protocols. The microwavable resin, polymerised by fast cycle and autopolymerising resin should be avoided for processing denture and denture repairs, respectively.
Gonadotropin‐releasing hormone: regulation of theGnRHgene
Authors: Lee Vien H. Y. , Lee Leo T. O. , Chow Billy K. C.
Published: October 2008

As the key regulator of reproduction, gonadotropin‐releasing hormone (GnRH) is released by neurons in the hypothalamus, and transported via the hypothalamo‐hypophyseal portal circulation to the anterior pituitary to trigger gonadotropin release for gonadal steroidogenesis and gametogenesis. To achieve appropriate reproductive function, mammals have precise regulatory mechanisms; one of these is the control of GnRH synthesis and release. In the past, the scarcity of GnRH neurons and their widespread distribution in the brain hindered the study ofGnRHgene expression. Until recently, the development ofGnRH‐expressing cell lines with properties similar to those ofin vivoGnRH neurons and also transgenic mice facilitatedGnRHgene regulation research. This minireview provides a summary of the molecular mechanisms for the control ofGnRH‐IandGnRH‐IIgene expression. These include basal transcription regulation, which involves essentialcis‐acting elements in theGnRH‐IandGnRH‐IIpromoters and interacting transcription factors, and also feedback control by gonadotropins and gonadal sex steroids. Other physiological stimuli, e.g. insulin and melatonin, will also be discussed.
Gonadotropin‐releasing hormone: GnRH receptor signaling in extrapituitary tissues
Authors: Cheung Lydia W. T. , Wong Alice S. T.
Published: October 2008

Gonadotropin‐releasing hormone (GnRH) has historically been known as a pituitary hormone; however, in the past few years, interest has been raised in locally produced, extrapituitary GnRH. GnRH receptor (GnRHR) was found to be expressed in normal human reproductive tissues (e.g. breast, endometrium, ovary, and prostate) and tumors derived from these tissues. Numerous studies have provided evidence for a role of GnRH in cell proliferation. More recently, we and others have reported a novel role for GnRH in other aspects of tumor progression, such as metastasis and angiogenesis. The multiple actions of GnRH could be linked to the divergence of signaling pathways that are activated by GnRHR. Recent observations also demonstrate cross‐talk between GnRHR and growth factor receptors. Intriguingly, the classical Gαq–11‐phospholipase C signal transduction pathway, known to function in pituitary gonadotropes, is not involved in GnRH actions at nonpituitary targets. Herein, we review the key findings on the role of GnRH in the control of tumor growth, progression, and dissemination. The emerging role of GnRHR in actin cytoskeleton remodeling (small Rho GTPases), expression and/or activity of adhesion molecules (integrins), proteolytic enzymes (matrix metalloproteinases) and angiogenic factors is explored. The signal transduction mechanisms of GnRHR in mediating these activities is described. Finally, we discuss how a common GnRHR may mediate different, even opposite, responses to GnRH in the same tissue/cell type and whether an additional receptor(s) for GnRH exists.
Gonadotropin‐releasing hormone and ovarian cancer: a functional and mechanistic overview
Authors: So Wai‐Kin , Cheng Jung‐Chien , Poon Song‐Ling , Leung Peter C. K.
Published: October 2008

The hypothalamic decapeptide gonadotropin‐releasing hormone (GnRH) is well known for its role in the control of pituitary gonadotropin secretion, but the hormone and receptor are also expressed in extrapituitary tissues and tumor cells, including epithelial ovarian cancers. It is hypothesized that they may function as a local autocrine regulatory system in nonpituitary contexts. Numerous studies have demonstrated a direct antiproliferative effect on ovarian cancer cell lines of GnRH and its synthetic analogs. This effect appears to be attributable to multiple steps in the GnRH signaling cascade, such as cell cycle arrest at G0/G1. In contrast to GnRH signaling in pituitary gonadotropes, the involvement of Gαq, protein kinase C and mitogen‐activated protein kinases is less apparent in neoplastic cells. Instead, in ovarian cancer cells, GnRH receptors appear to couple to the pertussis toxin‐sensitive protein Gαi, leading to the activation of protein phosphatase, which in turn interferes with growth factor‐induced mitogenic signals. Apoptotic involvement is still controversial, although GnRH analogs have been shown to protect cancer cells from doxorubicin‐induced apoptosis. Recently, data supporting a regulatory role of GnRH analogs in ovarian cancer cell migration/invasion have started to emerge. In this minireview, we summarize the current understanding of the antiproliferative actions of GnRH analogs, as well as the recent observations of GnRH effects on ovarian cancer cell apoptosis and motogenesis. The molecular mechanisms that mediate GnRH actions and the clinical applications of GnRH analogs in ovarian cancer patients are also discussed.
Fatty Acid Composition of California Grown Almonds
Authors: Sathe S.K. , Seeram N.P. , Kshirsagar H.H. , Heber D. , Lapsley K.A.
Published: October 2008

ABSTRACT:  Eight almond (Prunus dulcis L.) cultivars from 12 different California counties, collected during crop years 2004 to 2005 and 2005 to 2006, were extracted with petroleum ether. The extracts were subjected to GC‐MS analyses to determine fatty acid composition of soluble lipids. Results indicated palmitic (C16:0), oleic (C18:1), linoleic (C18:2), and α‐linolenic (C18:3) acid, respectively, accounted for 5.07% to 6.78%, 57.54% to 73.94%, 19.32% to 35.18%, and 0.04% to 0.10%; of the total lipids. Oleic and linoleic acid were inversely correlated (r=–0.99, P= 0.05) and together accounted for 91.16% to 94.29% of the total soluble lipids. Statistically, fatty acid composition was significantly affected by cultivar and county.
Evaluation and donor site morbidity of tibial bone graft in sinus lift operation
Authors: Miranda S.L. , Fonseca A.P.Z. , Guarnieri M.
Published: October 2008

Aim:  The use of autologous bone is a good option for bone grafts in implantology. The purpose of this study was to present advantages in harvesting the proximal tibial cancellous bone as an alternative in the sinus floor lifting procedure, seeking future installation of osseointegraded implants.

Materials and methods:  Between 2002 and 2006, 19 patients were attended, with age between 41 and 77, being 9 males and 10 females, in order to lift the maxillary sinus floor. The approach to the donor site was medial, because of the fact that this method brings minor risk of injury to anatomical structures.

Results:  All cases allowed the installation of osseointegraded implants. Only minor complications occurred, such as local ecchymosis and ecchymosis extending to foot. In all cases, ambulation was immediate.

Conclusions:  A good amount of bone could be harvested; scarce pain symptomatology was detected, and risk of complications could be considered very low in the donor site.
Presentation of a plasmablastic lymphoma in a human immunodeficiency virus‐positive patient after administration of an inferior alveolar dental block
Authors: McKenna Gerald , Manton Sarah
Published: October 2008

Human immunodeficiency virus (HIV) is a serious worldwide healthcare problem with implications for all healthcare workers. The reported oral manifestations of the disease are numerous and have been categorised according to the strength of their association with HIV infection. Oral non‐Hodgkin's lymphoma is strongly associated with HIV infection, and an increased incidence of such neoplasms is widely reported. This case report details the presentation of a rare subcategory of plasmablastic lymphoma in an HIV‐positive patient after administration of an inferior alveolar dental block to facilitate extraction of mandibular teeth. This highly aggressive neoplasm is a large B‐cell lymphoma with a predilection for the oral cavity. Unfortunately, the prognosis for such a tumour is poor as detailed in this case.
Palatal mucormycosis: a rare clinical dilemma
Authors: Shetty S.R. , Punnya V.A.
Published: October 2008

Mucormycosis, caused by saprophytic fungi of class zygomycetes, is a rare opportunistic, fungal infection which has a rapidly progressive and fulminant course with fatal outcome. Rarity of the disease frequently impairs diagnosis leading to worsened prognosis for patients. The present article describes a case of mucormycosis affecting the palate in a patient with uncontrolled diabetes mellitus which was successfully treated with combined therapy. The aim of this article was to emphasise the occurrence of this entity in oral cavity especially in a background of immunosuppresion and to discuss the importance of its early diagnosis to allow prompt and aggressive therapy.
Replacement of congenically missing maxillary permanent canine with a zirconium oxide dental implant and crown. A case report from an ongoing clinical study
Authors: Oliva X. , Oliva J. , Oliva J.D.
Published: October 2008

This article describes a case report of an ongoing clinical investigation with zirconium oxide (ZrO2) dental implants. The patient was a young female who was missing an upper right canine. A one‐piece (implant + abutment) ZrO2 implant (CeraRoot) with acid‐etched surface (ICE surface®) was implanted. The preoperative situation was ideal in terms of soft tissue and bone preservation, and the surgery was done transmucosally without having to raise a flap. The soft tissue healed successfully around the implants within few days. The case was finally restored with a ZrO2 crown (CeraCrown) and ceramic characterisation.
Osteodystrophy and brown tumour causing localised jaw enlargement
Authors: De Lacerda Júlio César Tanos , Gomes Carolina Cavaliéri , E Oliveira Carla da Silveira , Gomez Ricardo Santiago
Published: October 2008

Chronic renal disease is characterised by progressive and irreversible loss of renal function. A number of systemic and oral complications are associated with chronic renal disease. We report a rare case of jaw enlargement caused by the simultaneous presence of osteitis fibrosis and brown tumour secondary to hyperparathyroidism. Both conditions are related to increased levels of parathyroid hormone and dental surgeons should be aware of this important complication associated with chronic renal disease.
A classification system of mandibular prognathism
Authors: Cho H.J. , Nguyen T.
Published: October 2008

Aim:  To provide a classification system of mandibular prognathism (MP) as a guide for proper diagnosis and treatment planning of the various forms of skeletal discrepancies seen in mandibular prognathism and to a communication tool among orthodontists and surgeons.

Materials and Methods:  Six different types of MP were presented. Recommended surgical procedures for each MP categories were presented. Twenty‐three consecutive MP patients were evaluated by a panel of three orthodontists. The panel categorized each patient according to Cho's MP classification system. The recommended surgery by the MP classification system and actual surgery performed for each were compared.

Result:  The recommended surgical procedure(s) respective to the MP category of each individual corresponded to the actual surgery performed with exception of a few individuals.

Conclusion:  This MP classification system proved to be a good diagnostic tool and led to an appropriate orthodontic and surgical treatment plan.
Different topoisomerase IIa protein expression patterns affect prognosis in tongue squamous cell carcinoma: a quantitative digital image analysis study
Authors: Machaira A. , Tsiambas E. , Goula K. , Chrysomali E. , Nikolatou O. , Manaios L. , Rapidis A.D. , Karameris A. , Patsouris E.
Published: October 2008

Aim:  Topoisomerases represent a class of nucleic enzymes involved in the DNA replication, transcription and also chromosome topological formation. Topoisomerase IIa (Topo Iia – gene location 17q21) inhibition promotes cell death and for this reason, it is a target for specific chemotherapy (anthracyclines, podophyllotoxines). Our aim was to investigate the potential prognostic significance of its protein expression in squamous cell carcinomas of the tongue (TSCCs) based on a quantitative, digital image analysis method.

Materials and methods:  We analysed immunohistochemically eighty‐seven (n = 87) archival, primary TSCCs using a monoclonal anti‐Topo IIa antibody. A computerised image analysis assay was applied for the evaluation of the results [nuclear labelling index (NLI)]. Survival analysis was also performed.

Results:  Topo IIa protein was overexpressed in 48/87 (55.1%) cases. High NLI values were detected in 17/48 (35.4%), whereas moderate levels of expression were detected in 31/48 (64.6%) cases. Statistical significance was not assessed correlating overall protein expression to grade or stage of the examined tumours (P = 0.88, P = 0.73, respectively), but only to the anatomical region (P = 0.04). Cox regression analysis showed that Topo IIa and also the size of the tumours were strongly associated to the survival of the patients (P = 0.01, P = 0.02, respectively).

Conclusions:  Topo IIa protein overexpression is a frequent event in TSCCs. Topo IIa may be used as a prognostic factor and also as a basis for targeted chemotherapy strategies in TSCCs. Furthermore, digital image analysis improves the quantification of immunohistochemical stains in an accurate and fast way.
Development of 14 minisatellite markers for the citrus canker bacterium, Xanthomonas citri pv. citri
Authors: NGOC L. BUI THI , VERNIERE C. , VITAL K. , GUERIN F. , GAGNEVIN L. , BRISSE S. , AH‐YOU N. , PRUVOST O.
Published: October 2008

We screened the genome of Xanthomonas citri pv. citri strain 306 for tandem repeats. A multiplex polymerase chain reaction protocol was used to assess the genetic diversity of 239 strains of X. citri pv. citri from Asia. The total number of alleles per locus ranged from three to 20. Using pooled data sets, 223 different haplotypes were identified. Successful amplifications were obtained at most loci for seven other X. citri pathovars. This typing scheme is expected to be useful at different spatial scales for population studies of pathovars of X. citri, several of which cause plant diseases of economic importance.
Characterization of microsatellite loci in the subsocial spider Stegodyphus lineatus (Araneae: Eresidae)
Authors: BILDE T. , TUNI C. , CARIANI A. , SANTINI A. , TABARRONI C. , GAROIA F. , GOODACRE S. L.
Published: October 2008

Stegodyphus lineatus spiders live in groups consisting of closely related individuals. There appears to be no discrimination against related individuals as mates but females mate multiply, despite the fact that matings are shown to carry a cost. We have developed eight polymorphic dinucleotide microsatellite markers that allow us to assess levels of heterozygosity and relatedness among individuals of this species. These molecular markers are likely to prove highly effective tools for estimating levels of inbreeding and thus allow us to test hypotheses about the relationships between social structure, mating strategies and inbreeding avoidance.
Development and characterization of 12 polymorphic microsatellite loci in the American dog tick (Dermacentor variabilis)
Authors: DHARMARAJAN GUHA , FIKE JENNIFER A. , BEASLEY JAMES C. , RHODES JR OLIN E.
Published: October 2008

Twelve polymorphic microsatellite loci were developed for the American dog tick (Dermacentor variabilis), an important vector of infectious diseases in humans and animals. Four multiplexed panels comprising the loci were developed and 45 ticks collected from two raccoons (Procyon lotor) were genotyped. The number of alleles per locus ranged from nine to 30, and single locus heterozygosities ranged from 0.18 to 0.93. Data generated using these markers will further our understanding of factors affecting gene flow in D. variabilis, thus helping to elucidate the transmission dynamics of diseases associated with this vector.
Characterization of 13 microsatellites for Lahontan cutthroat trout (Oncorhynchus clarki henshawi) and cross‐amplification in six other salmonids
Authors: ROBINSON M. L. , KIRCHOFF V. S. , PEACOCK M. M.
Published: October 2008

Thirteen newly developed tri‐ and tetranucleotide repeat microsatellite markers were developed for Lahontan cutthroat trout (Oncorhynchus clarki henshawi), a threatened subspecies endemic to the Lahontan hydrographic basin in the western USA. These loci are highly polymorphic with five to 30 alleles per locus and observed heterozygosities ranging from 0.4 to 0.7. Cross‐species amplification of these markers was most successful in the closely related rainbow trout, Oncorhynchus mykiss, with only three loci amplifying in brown trout, Salmo trutta. Nonoverlapping allelic distributions for many of these loci among the six salmonid species screened suggest these markers may be useful for hybrid determination.
Identification and characterization of microsatellite markers from the starfish Asterina pectinifera expressed sequence tags
Authors: LI QI , NI GANG , LIU JUN , LI JINGJING , KONG LINGFENG
Published: October 2008

The starfish (Asterina pectinifera) is a common species widely distributed along the coasts of East Asia. Nevertheless, little information is currently available about the genetic characteristics of native populations. In this survey, the first set of 14 microsatellite markers for the starfish was developed from expressed sequence tag databases. They were characterized using 40 samples. Number of alleles per locus ranged from three to 14. The observed and expected heterozygosities ranged from 0.300 to 0.825 and from 0.479 to 0.919, respectively. These informative microsatellite markers will be useful in studies of population genetic structure for this species.
Three-Dimensional Large Amplitude Body Motions in Waves
Authors: Zhang Xinshu , Beck Robert F.
Published: October 2008

Three-dimensional, time-domain, wave-body interactions are studied in this paper for cases with and without forward speed. In the present approach, an exact body boundary condition and linearized free surface boundary conditions are used. By distributing desingularized sources above the calm water surface and using constant-strength flat panels on the exact wetted body surface, the boundary integral equations are numerically solved at each time step. Once the fluid velocities on the free surface are computed, the free surface elevation and potential are updated by integrating the free surface boundary conditions. After each time step, the body surface and free surface are regrided due to the instantaneous wetted body geometry. The desingularized method applied on the free surface produces nonsingular kernels in the integral equations by moving the fundamental singularities a small distance outside of the fluid domain. Constant-strength flat panels are used for bodies with any arbitrary shape. Extensive results are presented to validate the efficiency of the present method. These results include the added mass and damping computations for a hemisphere. The calm water wave resistance for a submerged spheroid and a Wigley hull are also presented. All the computations with forward speed are started from rest and proceeded until a steady state is reached. Finally, the time-domain forced motion results for a modified Wigley hull with forward speed are shown and compared to the experiments for both linear computations and body-exact computations.
Certification of Marine Energy Converters: The Experience so Far
Authors: Ferreira Claudio Bittencourt
Published: October 2008

In the past few years, DNV has been involved in a variety of projects related to marine energy converters. All projects have been characterized for the handling of technical uncertainties due to the application of new technology or proven technology in different areas of application. A systematic approach based on the DNV RP-A203 Qualification of New Technology was applied combined with the Guidelines for Design and Operation of Wave Energy Converters (May 2005—work carried out by DNV under Commission of Carbon Trust as part of Marine Energy Challenge) to steer the third party activity, but, more importantly, to allow developers to systematically identify and deal with the risks in a rational manner with traceability of decisions throughout the development of the energy converter. From the very start of our engagement, it was clear that the handling of technical uncertainties was affected, not only by the technical barriers, but also by financial and time constraints. The establishment of the safety and functional targets to be achieved by the energy converter are to be based, not only on the safety and asset integrity aspects, but also on the financial∕business model. The experience of using the qualification process and the guidelines on these projects, achieving the right balance between the constraints, handling of uncertainties, financial targets, and safety and functional requirements, are briefly described in this paper as well as the future steps to be taken to improve the process and consolidate the experience so far. In this paper, the use of the DNV OSS-312 (Certification of Wave and Tidal Energy Converters) on the certification process of marine energy converters is also addressed.
A Finite Element Analysis for Unbonded Flexible Risers Under Torsion
Authors: Bahtui A. , Bahai H. , Alfano G.
Published: October 2008

This paper presents a detailed finite-element analysis of unbonded flexible risers. The numerical results are compared to the analytical solutions for various load cases. In the finite-element model, all layers are modeled separately with contact interfaces between each layer. The finite-element model includes the main features of the riser geometry with very little simplifying assumptions made. The numerical model was solved using a fully explicit time-integration scheme implemented in a parallel environment on a 16-processor cluster. The very good agreement found from numerical and analytical comparisons validates the use of our numerical model to provide benchmark solutions against which further detailed investigation will be made.
A Monte Carlo Approach to Prediction of Extreme Response Statistics of Drag Dominated Offshore Structures
Authors: Naess Arvid , Gaidai Oleg
Published: October 2008

The focus of the present paper is the extreme response statistics of drag dominated offshore structures subjected to harsh weather conditions. More specifically, severe sea states both with and without strong current are considered. The nature of the hydrodynamic forces acting on the structure becomes highly nonlinear. In addition to the drag forces, the so called inundation effect due to the wave elevation, corrected to include second order waves, is also taken into account. In the present paper, the Monte Carlo method along with a special extrapolation technique is applied. The proposed method opens up for the possibility to predict simply and efficiently long-term extreme response statistics, which is an important issue for the design of offshore structures.
Influence of Catalyst Properties and Reactor Configuration on the Photocatalytic Degradation of Trichloroethylene Under Sunlight Irradiation
Authors: Coronado Juan M. , Sánchez Benigno , Fresno Fernando , Suárez Silvia , Portela Raquel
Published: October 2008

In this work, the influence of the reactor configuration and the characteristics of the catalysts on the photodegradation of trichloroethylene (TCE) vapors are studied under sunlight illumination. The photocatalytic activity tests were carried out using two types of continuous flow reactors: (i) a compound parabolic collector (CPC) and (ii) a simple flat reactor. Three different photocatalysts based on TiO2 were utilized: (i) commercial powders calcined at 500°C (ii) a TiO2−xNx sample synthesized by treating the commercial sample at 500°C in an NH3 gas flow, and (iii) TiO2 thin film coatings on differently shaped borosilicate glass supports prepared by a sol-gel procedure. The obtained data reveal that the photonic efficiency for the removal of TCE is quite high but slightly decreases with increasing the light intensity. The commercial TiO2 sample presents the highest efficiency while nitrogen doping seems to be slightly detrimental for photoactivity, despite the fact that certain photoresponse in the visible can be envisaged. In contrast, transparent sol-gel TiO2 coatings present the highest TCE degradation rate per mass of catalyst. Regarding the type of reactor, it is found that the use of CPCs can be advantageous, especially when dealing with high volumes of effluent and elevated concentration of TCE, although flat reactor also shows a considerable efficiency.
Comparative Study of Phenolics Degradation Between Biological and Photocatalytic Systems
Authors: Herrera Melián J. A. , Araña J. , Ortega J. A. , Martín Muñoz F. , Tello Rendón E. , Pérez Peña J.
Published: October 2008

Phenol and phenol compounds are toxic organics that can be found in many industrial wastewaters. Biological wastewater treatments are considered to be the most convenient methods owing to their efficiency and low economic cost. Nonetheless, many organic pollutants are refractory to bacterial degradation. Photocatalytic methods can be an interesting alternative as pretreatment to improve biodegradability and reduce toxicity of industrial effluents. The goal of this study was to compare and combine TiO2-photocatalysis with constructed wetlands to obtain a low-cost method for the treatment of phenolic wastewater. The degradation of phenol was studied by means of TiO2-photocatalysis (solar and UV-lamp) in batch reactors. The degradations of phenol and two of its photocatalytic degradation intermediates, catechol and hydroquinone, were studied in wetland reactors with and without two wetland plants: common reed (Phragmites australis) and papyrus (Cyperus alternifolius). The application of pseudo first-order kinetics to the elimination of phenol in the wetland reactors provided high correlation coefficients (R2=0.85–0.99), allowing the comparison of the biological and photocatalytic methods. Although higher concentrations of phenol (250–400mg∕l) could be treated, the elimination of 50ppm was usually accomplished in batch experiments in less than 15h, the time in which low or nil solar radiation is available for TiO2-photocatalysis. As a consequence, this concentration can be considered to be the upper limit for the wetland influent. The degradations of catechol and hydroquinone showed higher rate constants (0.2–0.4h−1) than that of phenol (about 0.15h−1), particularly in the reactor with common reed (1–2h−1). The degradation of phenol by the photocatalytic methods was three to four times faster than those obtained with the wetland reactors. By using solar TiO2-photocatalysis, concentrations of phenol up to 100ppm were reduced down to 16ppm and 27ppm of phenol and hydroquinone, respectively, in about 7h. However, it was toxic. When this sample was continuously (38ml∕min) added to wetland reactors with common reed, phenol and hydroquinone concentrations were below their detection limits (1ppm and 2ppm, respectively). Solar TiO2-photocatalysis is a promising technique for the treatment of phenol but its application is limited to daytime periods with appropriate weather conditions. Constructed wetlands can also eliminate phenol and phenolic compounds without these limitations, but the toxicity of the influent must be as low as possible. The combination of both methods can provide a low-cost method for the treatment of phenolic wastewater.
Photocatalytic Degradation of Dibutyl Phthalate: Effect of Catalyst Immobilization
Authors: Bajt O. , Zita J. , Novotná P. , Krýsa J. , Jirkovský J.
Published: October 2008

The degradation processes of dibutyl phthalate (DBP), an important pollutant, are rather slow and do not lead to the complete decomposition. In the present work the photocatalytic degradation of dibutyl phthalate in the presence of TiO2 was studied. Experiments were carried out in suspensions and with immobilized layers, prepared from powder suspensions and by sol-gel technique. Two different polychromatic light sources (band maxima at 350nm and 365nm) were used for irradiation. The results confirmed that the photocatalytic degradation of DBP using TiO2 is an efficient degradation process and proceeds even at very low concentration of photocatalyst (0.001gdm−3). Reaction rates were significantly higher in the case of the lamp with the maximum at 365nm, which is due to the higher light intensity of this lamp. At comparable TiO2 amount P25 layers exhibit about 50% of photoactivity using TiO2 suspension.
Study of Fluorine-Doped TiO2 Sol-Gel Thin Coatings
Authors: Giannakopoulou T. , Todorova N. , Vaimakis T. , Ladas S. , Trapalis C.
Published: October 2008

Ti O 2 is an excellent material for degradation of many environmental contaminants. Its photocatalytic activity is restricted by UV spectral region that can be extended to visible region using different doping techniques. Effect of fluorine-doping on the optical properties of sol-gel prepared TiO2 thin films is reported. Trifluoroacetic acid (CF3COOH) was used as fluorine source with starting concentrations of 5at.%, 10at.%, and 20at.% F to Ti. Gel films were deposited on SiO2∕soda lime glass substrates by dip-coating technique. After thermal treatment at 450°C fluorine containing TiO2 thin films were obtained. The crystallinity of the films was determined by X-ray diffraction (XRD). The X-ray photoemission spectrometry (XPS) was applied to determine valence state of the dopant and bonding element. The optical constants, namely, refractive index and the extinction coefficient, were obtained by fitting UV-visible theoretical transmittance curves to experimental ones. The simulated transmittance was calculated in the frames of the Forouhi–Bloomer (FB) dispersion model. The values of the FB energy band gap determined as onset of the absorption were compared with Tauc band gap values received by extrapolation of the linear part of the absorption edge. The XRD patterns reflect beginning of the anatase crystallization process. The XPS analysis reveals the presence of fluorine in the films in the form of titanium fluoride, titanium oxyfluorides, and nonstoichiometric TiO2−xFx. The linear part of the absorption edge of TiO2 films for mentioned fluorine concentrations gives slightly increased values of Tauc band gap (∼3.7eV) than that for bulk TiO2(∼3.2eV). Also, its broadening at lower frequencies with a FB band gap ∼2.7eV is observed. The results show that, although the fluorine is incorporated in the TiO2 lattice, it does not affect the crystallinity and band gap of the formed TiO2 film for the F∕Ti ratios used in the starting sols.
Preparation and Characterization of Nanocrystalline Pt/TCG Counterelectrodes for Dye-Sensitized Solar Cells
Authors: Katsanaki Antigoni V. , Tsoukleris Dimitris S. , Falaras Polycarpos , Karayianni Haido S. , Bernard Marie-Claude
Published: October 2008

Transparent counter electrodes were prepared on transparent conductive glass (TCG) substrates from a hexachloroplatinic acid (H2PtCl6) solution applying the thermal decomposition method in combination with the spin-coating deposition technique. The effect of the precursor concentration and the number of deposited platinum layers on the surface characteristics of the Pt films was examined, and the relation between those surface characteristics and the electrochemical properties of the corresponding modified Pt/TCG electrodes was defined. Four types of counterelectrodes were prepared, differing in the concentration of the H2PtCl6 solution (0.03M and 0.15M) and in the number of Pt layers (one or two Pt layers); their performance as counterelectrodes was evaluated after their incorporation into dye-sensitized solar cells (DSSCs) employing a solid state redox electrolyte. The obtained results show that solar cells using counterelectrodes prepared from the 0.03MH2PtCl6 solution and consisting of two Pt layers (Pt032 electrode) exhibited the best performance characteristics (diffusion coefficient D*I3−=1.58×10−5cm2s−1, conversion efficiency η=2.16%, fill factor ff=62.14%, and short circuit photocurrent Isc=4.71mAcm−2). The electrochemical behavior of the modified counterelectrodes is consistent with the surface characteristics of the Pt film that formed on the conductive glass substrate, which seems to be significantly affected by the adopted method and the adjusted experimental parameters (Pt concentration and number of Pt layers). Specifically, this type of electrodes beside their low roughness (Rq=11.5nm), also presents a high complexity (Df=2.3). As a result, for this kind of solid state DSSCs, the less rough but the more complex the Pt/TCG electrode surface, the higher the efficiency of the corresponding solar cells.
Modeling of a Solar Seawater Desalination Plant for Automatic Operation Purposes
Authors: Roca Lidia , Yebra Luis J. , Berenguel Manuel , Alarcón-Padilla Diego C.
Published: October 2008

Desalination plants play a fundamental role in the fight against fresh water shortage in places with seawater availability. On the other hand, optimization of industrial processes is an important goal in order to increase operation efficiency and to minimize costs. This paper deals with an experimental hybrid solar-gas desalination system designed, built, and operated at the Plataforma Solar de Almería (Spain) under the framework of a European R&D project. This desalination system, based on a multieffect distillation process, is partially powered by a low temperature static solar collector field of a compound parabolic concentrator type. With the aim of performing an optimal operation of the plant working with the solar resource, process dynamics have to be studied and modeled. This paper shows control-oriented low complexity models for the solar field and thermal storage subsystems as well as a model of the distillate production rate depending on process temperature. These models are validated with real data with the objective of being useful in the evaluation of optimal operating points, the design of operational procedures, and the establishment of adequate control references to maximize the use of the solar resource and to improve process efficiency.
Two-Step Water Splitting Process With Solid Solution of YSZ and Ni-Ferrite for Solar Hydrogen Production (ISEC 2005-76151)
Authors: Ishihara Hideyuki , Kaneko Hiroshi , Hasegawa Noriko , Tamaura Yutaka
Published: October 2008

Ni-ferrite (NiFe2O4) is a promising reactive ceramics of the ferrite for the solar hydrogen production by a two-step water splitting process using concentrated solar energy. However, it should be pretreated before H2-generation reaction by grinding the Ni-ferrite sintered after the O2-releasing reaction to make a fine powder. If the Ni-ferrite and yttria stabilized zirconia (YSZ) form a solid solution between these oxides (YSZ∕NiFe2O4 solid solution=YSZ(Ni,Fe)), it is expected that the two-step water splitting process with the Ni-ferrite system can proceed without treatment of the reduced product because of the high thermal stability of the YSZ∕NiFe2O4 solid solution. The YSZ∕NiFe2O4 solid solution was prepared by calcination of the mixture of the YSZ balls and NiFe2O4 powder at T=1823K for 1h, and its reactivity and thermal stability were examined for the two-step water splitting process. During the ten times repetition of the two-step water splitting reaction (T=1773K for O2-releasing, and 1473K for H2-generation) with the YSZ∕NiFe2O4 solid solution using infrared imaging furnace, the reactivity for O2-releasing and H2-generation was kept constant. The molar ratio of the released O2 gas volume (the average O2 gas, 1.9cm3∕g) and the generated H2 gas volume (the average H2 gas, 3.8cm3∕g) was nearly 1:2, indicating that the water decomposition process via two steps proceeds. The X-ray diffractometry (XRD) measurement showed that the YSZ(Ni,Fe) keeps the YSZ phase structure during the ten times repetition of the two-step water splitting process. The successive H2 gas production by the two-step water splitting process was performed (ten times repetition of the two-step water splitting process). From comparative study on the reactivity and the thermal stability for the two-step water splitting reaction among the YSZ∕NiFe2O4 solid solution, NiFe2O4 and ZnFe2O4, it is concluded that the YSZ∕NiFe2O4 solid solution is superior to the others.
Concentrating PV: An Alternative to Calorimeters for Measuring High Solar Flux Densities
Authors: Fernández-Reche Jesús , Sánchez Marcelino , Alonso Miguel , Cañadas Inmaculada , Chenlo Faustino , Rodríguez José , Ballestrín Jesús
Published: October 2008

Gardon calorimetric transducers are widely used to measure concentrated solar radiation flux on solar thermal areas. These measurements need some correction to adapt their response from thermal to solar irradiance measurement. The authors propose the use of concentrating photovoltaic PV-cells to measure concentrated solar radiation flux. This paper shows the results obtained from a comparative test carried out in a solar furnace measuring concentrated solar irradiance with calorimetric and photovoltaic sensors, Gardon, and PV-Cells, respectively.
Analyzing Solar Power Plant Performance Through Data Mining
Authors: Maciejewski Henryk , Valenzuela Loreto , Berenguel Manuel , Fernández-Reche Jesús , Adamus Konrad , Jarnicki Michal
Published: October 2008

This work is devoted to application of data mining methods for monitoring of state of a solar thermal plant. The methods discussed are illustrated by example of a study performed for the DISS direct steam generation facility at the Plataforma Solar de Almeria (Spain). In order to deal with the problems of large dimensionality and high correlation among the data the methods of latent variables, principal component analysis and partial least squares, were applied. Results showed that normal and abnormal states during plant operation could be identified.
Computer Aided Synthesis of Piecewise Rational Motions for Spherical 2R and 3R Robot Arms
Authors: Purwar Anurag , Jin Zhe , Ge Q. J.
Published: October 2008

This paper deals with the problem of synthesizing smooth piecewise rational spherical motions of an object that satisfies the kinematic constraints imposed by a spherical robot arm with revolute joints. This paper brings together the kinematics of spherical robot arms and recently developed freeform rational motions to study the problem of synthesizing constrained rational motions for Cartesian motion planning. The kinematic constraints under consideration are workspace related constraints that limit the orientation of the end link of robot arms. This paper extends our previous work on synthesis of rational motions under the kinematic constraints of planar robot arms. Using quaternion kinematics of spherical arms, it is shown that the problem of synthesizing the Cartesian rational motion of a 2R arm can be reduced to that of circular interpolation in two separate planes. Furthermore, the problem of synthesizing the Cartesian rational motion of a spherical 3R arm can be reduced to that of constrained spline interpolation in two separate planes. We present algorithms for the generation of C1 and C2 continuous rational motion of spherical 2R and 3R robot arms.
New Considerations on the Theory of Type Synthesis of Fully Parallel Platforms
Authors: Rico José M. , Cervantes-Sánchez J. Jesús , Tadeo-Chávez Alejandro , Pérez-Soto Gerardo Israel , Rocha-Chavarría Juan
Published: October 2008

This contribution presents new considerations on the theory of type synthesis of fully parallel platforms. These considerations prove that the theory of type synthesis of fully parallel platforms can be dealt with by analyzing two types of fully parallel platforms, where the displacements of the moving platform generate a subgroup of the Euclidean group, SE(3), including in this type, 6DOF parallel platforms and lower mobility platforms or, more precisely, parallel platforms where the displacements of the moving platforms generate only a subset of the Euclidean group. The theory is based on an analysis of the subsets and subgroups of the Euclidean group, SE(3), and their intersections. The contribution shows that the different types of parallel platforms are determined by the intersections of the subgroups or subsets, of the Euclidean group, generated by the serial connecting chains or limbs of the parallel platform. From an analysis of the intersections of subgroups and subsets of the Euclidean group, this contribution presents three possibilities for the type synthesis of fully parallel platforms where the displacements of the moving platform generate a subgroup of the Euclidean group, and two possibilities for the type synthesis of fully parallel platforms where the displacements of the moving platforms generate only a subset of the Euclidean group. An example is provided for each one of these possibilities. Thus, once these possible types of synthesis are elucidated, the type synthesis of fully parallel platforms is just reduced to the synthesis of the serial connecting chains or limbs that generate the required subgroups or subsets of the Euclidean group.
A New Variable-Fidelity Optimization Framework Based on Model Fusion and Objective-Oriented Sequential Sampling
Authors: Xiong Ying , Chen Wei , Tsui Kwok-Leung
Published: October 2008

Computational models with variable fidelity have been widely used in engineering design. To alleviate the computational burden, surrogate models are used for optimization without directly invoking expensive high-fidelity simulations. In this work, a model fusion technique based on the Bayesian–Gaussian process modeling is employed to construct cheap surrogate models to integrate information from both low-fidelity and high-fidelity models, while the interpolation uncertainty of the surrogate model due to the lack of sufficient high-fidelity simulations is quantified. In contrast to space filling, the sequential sampling of a high-fidelity simulation model in our proposed framework is objective-oriented, aiming for improving a design objective. Strategy based on periodical switching criteria is studied, which is shown to be effective in guiding the sequential sampling of a high-fidelity model toward improving a design objective as well as reducing the interpolation uncertainty. A design confidence metric is proposed as the stopping criterion to facilitate design decision making against the interpolation uncertainty. Examples are provided to illustrate the key ideas and features of model fusion, sequential sampling, and design confidence—the three key elements in the proposed variable-fidelity optimization framework.