bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Requirements for gp80 Independence of Human Herpesvirus 8 Interleukin-6 (vIL-6) and Evidence for gp80 Stabilization of gp130 Signaling Complexes Inducedby vIL-6
Authors: Chen Daming , Nicholas John
Published: September 2006

Human herpesvirus 8 interleukin-6 (vIL-6) displays 25% amino acid identity
with human IL-6 (hIL-6) and shares an overall four-helix-bundle
structure and gp130-mediated STAT/mitogen-activated protein kinase
signaling with its cellular counterpart. However, vIL-6 is distinct in
that it can signal through gp130 alone, in the absence of the
nonsignaling gp80 α-subunit of the IL-6 receptor. To
investigate the structural requirements for gp80 independence of vIL-6,
a series of expression vectors encoding vIL-6/hIL-6 chimeric and
site-mutated IL-6 proteins was generated. The replacement of hIL-6
residues with three vIL-6-specific tryptophans implicated in gp80
independence from crystallographic studies or the A and C helices
containing these residues did not confer gp80 independence to hIL-6.
The N- and C-terminal regions of vIL-6 could be substituted with hIL-6
sequences with the retention of gp80-independent signaling, but
substitutions of other regions of vIL-6 (helix A, A/B loop, helix B,
helix C, and proximal half of helix D) with equivalent sequences of
hIL-6 abolished gp80 independence. Interestingly, the B helix of vIL-6
was absolutely required for gp80 independence, despite the fact that
this region contains no receptor-binding residues. Point mutational
analysis of helix C, which contains residues involved in physical and
functional interactions with gp130 domains 2 and 3 (cytokine-binding
homology region), identified a variant, VI
120
EE, that was
able to signal and dimerize gp130 only in the presence of gp80. gp80
was also found to stabilize gp130:g130 dimers induced by a distal D
helix variant of vIL-6 that was nonetheless able to signal
independently of gp80. Together, our data reveal the crucial importance
of overall vIL-6 structure and conformation for gp80-independent
signaling and provide functional and physical evidence of the
stabilization of vIL-6-induced gp130 signaling complexes by
gp80.
The 37/67-Kilodalton Laminin Receptor Is a Receptor for Adeno-Associated Virus Serotypes 8, 2, 3, and 9
Authors: Akache Bassel , Grimm Dirk , Pandey Kusum , Yant Stephen R. , Xu Hui , Kay Mark A.
Published: September 2006

Adeno-associated virus serotype 8 (AAV8) is currently emerging as a powerful gene transfer vector, owing to its capability to efficiently transduce many different tissues in vivo. While this is believed to be in part due to its ability to uncoat more readily than other AAV serotypes such as AAV2, understanding all the processes behind AAV8 transduction is important for its application and optimal use in human gene therapy. Here, we provide the first report of a cellular receptor for AAV8, the 37/67-kDa laminin receptor (LamR). We document binding of LamR to AAV8 capsid proteins and intact virions in vitro and demonstrate its contribution to AAV8 transduction of cultured cells and mouse liver in vivo. We also show that LamR plays a role in transduction by three other closely related serotypes (AAV2, -3, and -9). Sequence and deletion analysis allowed us to map LamR binding to two protein subdomains predicted to be exposed on the AAV capsid exterior. Use of LamR, which is constitutively expressed in many clinically relevant tissues and is overexpressed in numerous cancers, provides a molecular explanation for AAV8's broad tissue tropism. Along with its robust transduction efficiency, our findings support the continued development of AAV8-based vectors for clinical applications in humans, especially for tumor gene therapy.
Cross-Protection against Marburg Virus Strains by Using a Live, Attenuated Recombinant Vaccine
Authors: Daddario-DiCaprio Kathleen M. , Geisbert Thomas W. , Geisbert Joan B. , Ströher Ute , Hensley Lisa E. , Grolla Allen , Fritz Elizabeth A. , Feldmann Friederike , Feldmann Heinz , Jones Steven M.
Published: September 2006

Marburg virus (MARV) has been associated with sporadic episodes of hemorrhagic fever, including a recent highly publicized outbreak in Angola that produced severe disease and significant mortality in infected patients. MARV is also considered to have potential as a biological weapon. Recently, we reported the development of a promising attenuated, replication-competent vaccine against MARV based on recombinant vesicular stomatitis virus (VSV) expressing the glycoprotein of the Musoke strain of MARV (VSVΔG/MARVGP-Musoke). We used this vaccine to demonstrate complete protection of cynomolgus monkeys against a homologous MARV challenge. While these results are highly encouraging, an effective vaccine would need to confer protection against all relevant strains of MARV. Here, we evaluated the protective efficacy of the VSVΔG/MARVGP-Musoke vaccine against two heterologous MARV strains, the seemingly more pathogenic Angola strain and the more distantly related Ravn strain. In this study, seven cynomolgus monkeys were vaccinated with the VSVΔG/MARVGP-Musoke vector. Three of these animals were challenged with the Angola strain, three with the Ravn strain, and a single animal with the Musoke strain of MARV. Two animals served as controls and were each injected with a nonspecific VSV vector; these controls were challenged with the Angola and Ravn strains, respectively. Both controls succumbed to challenge by day 8. However, none of the specifically vaccinated animals showed any evidence of illness either from the vaccination or from the MARV challenges and all of these animals survived. These data suggest that the VSVΔG/MARVGP-Musoke vaccine should be sufficient to protect against all known MARV strains.
Peripheral Blood B-Cell Death Compensates for Excessive Proliferation in Lymphoid Tissues and Maintains Homeostasis in Bovine Leukemia Virus-InfectedSheep
Authors: Debacq Christophe , Gillet Nicolas , Asquith Becca , Sanchez-Alcaraz Maria Teresa , Florins Arnaud , Boxus Mathieu , Schwartz-Cornil Isabelle , Bonneau Michel , Jean Geneviève , Kerkhofs Pierre , Hay Jack , Théwis André , Kettmann Richard , Willems Luc
Published: September 2006

The size of a lymphocyte population is primarily determined by a dynamic equilibrium between cell proliferation and death. Hence, lymphocyte recirculation between the peripheral blood and lymphoid tissues is a key determinant in the maintenance of cell homeostasis. Insights into these mechanisms can be gathered from large-animal models, where lymphatic cannulation from individual lymph nodes is possible. In this study, we assessed in vivo lymphocyte trafficking in bovine leukemia virus (BLV)-infected sheep. With a carboxyfluorescein diacetate succinimidyl ester labeling technique, we demonstrate that the dynamics of lymphocyte recirculation is unaltered but that accelerated proliferation in the lymphoid tissues is compensated for by increased death in the peripheral blood cell population. Lymphocyte homeostasis is thus maintained by biphasic kinetics in two distinct tissues, emphasizing a very dynamic process during BLV infection.
Mapping and Functional Role of the Self-Association Domain of Vesicular Stomatitis Virus Phosphoprotein
Authors: Chen Mingzhou , Ogino Tomoaki , Banerjee Amiya K.
Published: September 2006

The phosphoprotein (P protein) of vesicular stomatitis virus (VSV) is an essential subunit of the viral RNA-dependent RNA polymerase complex and plays a central role in viral transcription and replication. Using both the yeast two-hybrid system and coimmunoprecipitation assays, we confirmed the self-association of the P protein of Indiana serotype (Pind) and heterotypic interaction between Pind and the P protein of New Jersey serotype (Pnj). Furthermore, by using various truncation and deletion mutants of Pind, the self-association domain of the Pind protein was mapped to amino acids 161 to 210 within the hinge region. The self-association domain of Pind protein is not required for its binding to nucleocapsid and large proteins. We further demonstrated that the self-association domain of Pind protein is essential for VSV transcription in a minireplicon system and that a synthetic peptide spanning amino acids 191 to 210 in the self-association domain of Pind protein strongly inhibited the transcription of the VSV genome in vitro in a dose-dependent manner. These results indicated that the self-association domain of Pind protein plays a critical role in VSV transcription.
Human ESCRT-II Complex and Its Role in Human Immunodeficiency Virus Type 1 Release
Authors: Langelier Charles , von Schwedler Uta K. , Fisher Robert D. , De Domenico Ivana , White Paul L. , Hill Christopher P. , Kaplan Jerry , Ward Diane , Sundquist Wesley I.
Published: September 2006

The budding of many enveloped RNA viruses, including human immunodeficiency virus type 1 (HIV-1), requires some of the same cellular machinery as vesicle formation at the multivesicular body (MVB). In
Saccharomyces cerevisiae
, the ESCRT-II complex performs a central role in MVB protein sorting and vesicle formation, as it is recruited by the upstream ESCRT-I complex and nucleates assembly of the downstream ESCRT-III complex. Here, we report that the three subunits of human ESCRT-II, EAP20, EAP30, and EAP45, have a number of properties in common with their yeast orthologs. Specifically, EAP45 bound ubiquitin via its N-terminal GRAM-like ubiquitin-binding in EAP45 (GLUE) domain, both EAP45 and EAP30 bound the C-terminal domain of TSG101/ESCRT-I, and EAP20 bound the N-terminal half of CHMP6/ESCRT-III. Consistent with its expected role in MVB vesicle formation, (i) human ESCRT-II localized to endosomal membranes in a VPS4-dependent fashion and (ii) depletion of EAP20/ESCRT-II and CHMP6/ESCRT-III inhibited lysosomal targeting and downregulation of the epidermal growth factor receptor, albeit to a lesser extent than depletion of TSG101/ESCRT-I. Nevertheless, HIV-1 release and infectivity were not reduced by efficient small interfering RNA depletion of EAP20/ESCRT-II or CHMP6/ESCRT-III. These observations indicate that there are probably multiple pathways for protein sorting/MVB vesicle formation in human cells and that HIV-1 does not utilize an ESCRT-II-dependent pathway to leave the cell.
Site-Directed Antibodies against the Stem Region Reveal Low pH-Induced Conformational Changes of the Semliki Forest Virus Fusion Protein
Authors: Liao Maofu , Kielian Margaret
Published: September 2006

The E1 envelope protein of the alphavirus Semliki Forest virus (SFV) is a class II fusion protein that mediates low pH-triggered membrane fusion during virus infection. Like other class I and class II fusion proteins, during fusion E1 inserts into the target membrane and rearranges to form a trimeric hairpin structure. The postfusion structures of the alphavirus and flavivirus fusion proteins suggest that the “stem” region connecting the fusion protein domain III to the transmembrane domain interacts along the trimer core during the low pH-induced conformational change. However, the location of the E1 stem in the SFV particle and its rearrangement and functional importance during fusion are not known. We developed site-directed polyclonal antibodies to the N- or C-terminal regions of the SFV E1 stem and used them to study the stem during fusion. The E1 stem was hidden on neutral pH virus but became accessible after low pH-triggered dissociation of the E2/E1 heterodimer. The stem packed onto the trimer core in the postfusion conformation and became inaccessible to antibody binding. Generation of the E1 homotrimer on fusion-incompetent membranes identified an intermediate conformation in which domain III had folded back but stem packing was incomplete. Our data suggest that E1 hairpin formation occurs by the sequential packing of domain III and the stem onto the trimer core and indicate a tight correlation between stem packing and membrane merger.
Brd4 Is Required for E2-Mediated Transcriptional Activation but Not Genome Partitioning of All Papillomaviruses
Authors: McPhillips M. G. , Oliveira J. G. , Spindler J. E. , Mitra R. , McBride A. A.
Published: September 2006

Bromodomain protein 4 (Brd4) has been identified as the cellular binding target through which the E2 protein of bovine papillomavirus type 1 links the viral genome to mitotic chromosomes. This tethering ensures retention and efficient partitioning of genomes to daughter cells following cell division. E2 is also a regulator of viral gene expression and a replication factor, in association with the viral E1 protein. In this study, we show that E2 proteins from a wide range of papillomaviruses interact with Brd4, albeit with variations in efficiency. Moreover, disruption of the E2-Brd4 interaction abrogates the transactivation function of E2, indicating that Brd4 is required for E2-mediated transactivation of all papillomaviruses. However, the interaction of E2 and Brd4 is not required for genome partitioning of all papillomaviruses since a number of papillomavirus E2 proteins associate with mitotic chromosomes independently of Brd4 binding. Furthermore, mutations in E2 that disrupt the interaction with Brd4 do not affect the ability of these E2s to associate with chromosomes. Thus, while all papillomaviruses attach their genomes to cellular chromosomes to facilitate genome segregation, they target different cellular binding partners. In summary, the E2 proteins from many papillomaviruses, including the clinically important alpha genus human papillomaviruses, interact with Brd4 to mediate transcriptional activation function but not all depend on this interaction to efficiently associate with mitotic chromosomes.
Proteolytic Activation of Influenza Viruses by Serine Proteases TMPRSS2 and HAT from Human Airway Epithelium
Authors: Böttcher Eva , Matrosovich Tatyana , Beyerle Michaela , Klenk Hans-Dieter , Garten Wolfgang , Matrosovich Mikhail
Published: September 2006

Host cell proteases that cleave the hemagglutinin (HA) of influenza viruses in the human respiratory tract are still not identified. Here we cloned two human type II transmembrane serine proteases with known airway localization, TMPRSS2 and HAT, into mammalian expression vector. Cotransfection of mammalian cells with plasmids encoding HA and either protease resulted in HA cleavage in situ. Transient expression of either protease in MDCK cells enabled multicycle replication of influenza viruses in these cells in the absence of exogenous trypsin. These data suggest that TMPRSS2 and HAT are candidates for proteolytic activation of influenza viruses in vivo.
Herpes Simplex Virus ICP27 Is Required for Virus-Induced Stabilization of the ARE-Containing IEX-1 mRNA Encoded by the Human IER3 Gene
Authors: Corcoran Jennifer A. , Hsu Wei-Li , Smiley James R.
Published: September 2006

Herpes simplex virus (HSV) stifles cellular gene expression during productive infection of permissive cells, thereby diminishing host responses to infection. Host shutoff is achieved largely through the complementary actions of two viral proteins, ICP27 and virion host shutoff (vhs), that inhibit cellular mRNA biogenesis and trigger global mRNA decay, respectively. Although most cellular mRNAs are thus depleted, some instead increase in abundance after infection; perhaps surprisingly, some of these contain AU-rich instability elements (AREs) in their 3′-untranslated regions. ARE-containing mRNAs normally undergo rapid decay; however, their stability can increase in response to signals such as cytokines and virus infection that activate the p38/MK2 mitogen-activated protein kinase (MAPK) pathway. We and others have shown that HSV infection stabilizes the ARE mRNA encoding the stress-inducible IEX-1 mRNA, and a previous report from another laboratory has suggested vhs is responsible for this effect. However, we now report that ICP27 is essential for IEX-1 mRNA stabilization whereas vhs plays little if any role. A recent report has documented that ICP27 activates the p38 MAPK pathway, and we detected a strong correlation between this activity and stabilization of IEX-1 mRNA by using a panel of HSV type 1 (HSV-1) isolates bearing an array of previously characterized ICP27 mutations. Furthermore, IEX-1 mRNA stabilization was abrogated by the p38 inhibitor SB203580. Taken together, these data indicate that the HSV-1 immediate-early protein ICP27 alters turnover of the ARE-containing message IEX-1 by activating p38. As many ARE mRNAs encode proinflammatory cytokines or other immediate-early response proteins, some of which may limit viral replication, it will be of great interest to determine if ICP27 mediates stabilization of many or all ARE-containing mRNAs.
Induction of Cell-Cell Fusion from Without by Human Herpesvirus 6B
Authors: Pedersen Simon Metz , Øster Bodil , Bundgaard Bettina , Höllsberg Per
Published: September 2006

Human herpesvirus (HHV) 6A induce fusion from without (FFWO), whereas HHV-6B is believed to be ineffective in this process. Here, we demonstrate that HHV-6B induces rapid fusion in both epithelial cells and lymphocytes. The fusion was identified 1 h postinfection, could be inhibited by antibodies to HHV-6B gH and to the cellular receptor CD46, and was dependent on virus titer but independent of de novo protein synthesis and UV inactivation of the virus. Comparisons indicate that HHV-6A is only 10-fold more effective in inducing FFWO than HHV-6B. These data demonstrate that HHV-6B can induce FFWO in epithelial cells and lymphocytes.
Terbium Binding in Highly Luminescent Polymer Complexes
Authors: Kukla Stanislav , Cimrová Věra , Výprachtický Drahomír
Published: September 2006

Polymer ligands containing a covalently bonded quinolinone fluorophore and COOH (L1) or COONa (L2) binding sites were synthesized by the reaction of high-molecular-weight poly[styrene-alt-(maleic anhydride)] with 7-amino-4-methylquinolin-2(1H)-one and methanol and subsequent neutralization. The ligand-to-metal energy transfer and ligand binding properties in a series of [Tb(III)-ligand] complexes were investigated by steady-state and time-resolved luminescence spectroscopy in methanol or deuterated methanol. The intensity of the long-lived terbium(III) ion emission at 490, 545, 585 and 620 nm was greatly enhanced upon addition of L1 or L2. Based on the differences in luminescence data obtained for [Tb(III)-L1] and [Tb(III)-L2] complexes, a qualitative model for the interaction of terbium(III) ion with L1 and L2 is put forward. The experimental luminescence decay curves were double-exponential (τ1, τ2) with predominating longer component (rel B1 > 85%) for both [Tb(III)-L1] and [Tb(III)-L2] complexes. About 2.5 or 2 methanol molecules were coordinated to Tb3+ in [Tb(III)-L1] or [Tb(III)-L2] complexes, respectively, whereas ca. 6.5 methanol molecules were coordinated to Tb3+ in methanol.
Solid-Liquid and Liquid-Liquid Equilibrium in the Formamide-Acetophenone System
Authors: Sedláková Zuzana , Malijevská Ivona , Řehák Karel , Vrbka Pavel
Published: September 2006

Solid-liquid (s-l) and liquid-liquid (l-l) equilibrium was determined in the binary system formamide-acetophenone. The s-l equilibrium was measured by recording time-temperature cooling and warming curves. The l-l equilibrium was obtained in a wide range of temperatures by the turbidity method. A considerable supercooling preceding solidification made it possible to examine metastable l-l equilibrium yet at temperatures lower than the solidus ones. Activity coefficients evaluated from the stable region of l-l equilibrium were correlated by Novák's modification of the Wilson equation. Calculation of the s-l equilibrium was performed with the obtained parameters. Heat capacity of solid and liquid acetophenone was measured and its dependence on temperature is given. The transition enthalpy betwen two solid modifications of acetophenone is also given.
Charge Transfer Molecular Complexes of 4-(Dimethylamino)pyridine with Some Conventional and Unconventional Acceptors Involving Fluoroarenes
Authors: Rabie Usama M.
Published: September 2006

Charge transfer (CT) complexes of 4-(dimethylamino)pyridine (DMAP) with iodine as a typical σ-type acceptor and with typical π-type acceptor, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), have been synthesized and characterized. Octafluorotoluene (OFT), octafluoronaphthalene (OFN), perfluorophenanthrene (PFP), and 2,3,5,6-tetrafluoropyridine-4-carbonitrile (TFP) were also used as acceptors for interaction with DMAP. Properties of such CT complexes were investigated by UV/VIS and IR spectra, and elemental analyses of the isolated complexes. The systems DMAP-iodine and DMAP-DDQ are characterized by formation of triiodide ions (I3-) and DDQ•- anion radicals, respectively, which is proposed to occur via initial formation of outer-sphere CT complexes. The systems (DMAP-OFT, DMAP-OFN, DMAP-PFP and DMAP-TFP) are characterized by the appearance of new UV/VIS spectral bands assigned as CT bands; they also furnished the corresponding solid complexes with the stoichiometric ratio 1:1. 1H and 19F NMR spectra were used on confirming the formation of the DMAP-PFP CT complexes. The formation constants (KCT) and molar absorption coefficients (εCT) of the latter complex were obtained.
Synthesis, Self-Assembling and Redox Properties of 2-[(ω-Sulfanylalkyl)amino]-1,4-naphthoquinones
Authors: Kažemekaite Maryte , Railaite Vilma , Bulovas Arunas , Talaikyte Zita , Niaura Gediminas , Razumas Valdemaras , Butkus Eugenijus
Published: September 2006

The newly synthesized 1,4-naphthoquinones linked via nitrogen atom to a short chain with terminal sulfanyl group form self-assembled monolayers on gold. The main electrochemical parameters of the monolayers were determined by cyclic voltammetry. Combined voltammetric and in situ Fourier-transform surface-enhanced Raman spectroscopic studies of the Au electrode modified with the title compounds clearly evidence that naphthoquinone group transforms into naphthalenediol during a reduction process.
Comparative strength analyses of structural concrete columns
Authors: Mirza Sher Ali
Published: September 2006

A comparative study was undertaken of selected computational methods for predicting the strength determined from more than 500 physical tests of rectangular, tied structural concrete columns available in the literature. The study included 354 reinforced concrete and 150 composite steel–concrete columns. The computational methods compared were those of CSA A23.3-94 and Eurocode 2 for reinforced concrete and those of CSA A23.3-94 and Eurocode 4 for composite columns. The physical tests used for comparison were conducted on columns that were braced, pinned at both ends, subjected to short-term loads, and constructed using normal-density concrete with a compressive strength between approximately 17 and 57 MPa. Major variables included the concrete strength, the end eccentricity ratio, the slenderness ratio, the longitudinal reinforcing steel index for reinforced concrete or the structural steel index for composite columns, and the transverse reinforcement (tie/hoop) volumetric ratio. The study provided insights into the reliability of the computational methods examined. Recommendations for improving the CSA A23.3-94 procedure for the design of reinforced concrete and composite steel–concrete columns are also presented.Key words: columns, composite construction, computations, physical tests, reinforced concrete, reliability, strength.
Effects of driving forces and bending fatigue on structural performance of a novel concrete-filled fibre-reinforced-polymer tube flexural pile
Authors: Helmi Karim , Fam Amir , Mufti Aftab , Hall J Michael
Published: September 2006

The effects of driving forces and high-cycle fatigue on the flexural performance of a novel pile consisting of a concrete-filled glass-fibre-reinforced polymer (GFRP) tube (CFFT) are investigated. A 367 mm diameter CFFT pile was driven and then extracted from the ground. Two 6 m segments cut from the upper and lower ends of the pile were tested to failure under monotonic bending and compared with a similar undriven CFFT pile. In addition, a 625 mm diameter CFFT and a conventional 508 mm square prestressed concrete pile of similar moment capacities, both 13.1 m long, were driven, tested in the field under lateral loads, and compared. It was found that driving forces have a marginal effect (about 5% reduction) on the flexural strength of CFFT piles. Also, CFFT piles have larger deflections than prestressed piles do. Because the GFRP tube is the sole reinforcement for the CFFT system, a comprehensive fatigue test program was conducted: coupons cut from the tube were tested under cyclic loading at various stress levels (20%–60% of ultimate) to establish the S–N curve and stiffness-degradation characteristics of the tube. A full-scale 367 mm diameter and 6 m long CFFT pile was tested under reversed cyclic bending at 60% of ultimate moment to validate the coupon test results. It is recommended that the service moment be limited to 20%–30% of ultimate moment to achieve at least 1 million cycles.Key words: composite pile, CFFT, driving, bending, fatigue, cyclic, FRP, tension.
Creep of frozen slopes and ice-filled rock joints under temperature variation
Authors: Ladanyi Branko
Published: September 2006

Owing to climate warming trends, there has been an increasing interest in recent years in the accelerating creep of rock glaciers and frozen slopes. In the field of glaciology, the creep of glaciers has been extensively studied, observed, and analyzed for more than 100 years. Many valuable and detailed theoretical models have been proposed through the years for simulating the creep behavior of glaciers. This synthesis paper has no intention of proposing another one. Its purpose is only to supply to these models a potential geotechnical background, borrowed from the connected fields of frozen ground mechanics, rock mechanics, and the mechanics of mixtures. In particular, this paper attempts to extend some known models of mechanical behavior of unfrozen soil and rock masses to masses containing ice and to apply these models to large-scale creep of ice–rock mixtures and ice–rock interface problems under variable temperature and stress conditions.Key words: ice, rock, mixture, rock joints, slope stability, creep, temperature.
Shear strength of reinforced concrete beams with a fiber concrete matrix
Authors: Majdzadeh Fariborz , Soleimani Sayed Mohamad , Banthia Nemkumar
Published: September 2006

The purpose of this study was to investigate the influence of fiber reinforcement on the shear capacity of reinforced concrete (RC) beams. Both steel and synthetic fibers at variable volume fractions were investigated. Two series of tests were performed: structural tests, where RC beams were tested to failure under an applied four-point load; and materials tests, where companion fiber-reinforced concrete (FRC) prisms were tested under direct shear to obtain material properties such as shear strength and shear toughness. FRC test results indicated an almost linear increase in the shear strength of concrete with an increase in the fiber volume fraction. Fiber reinforcement enhanced the shear load capacity and shear deformation capacity of RC beams, but 1% fiber volume fraction was seen as optimal; no benefits were noted when the fiber volume fraction was increased beyond 1%. Finally, an equation is proposed to predict the shear capacity of RC beams.Key words: shear strength, fiber-reinforced concrete, RC beam, stirrups, energy absorption capacity, steel fiber, synthetic fiber.
Advanced modelling of concrete deterioration due to reinforcement corrosion
Authors: Isgor O Burkan , Razaqpur A Ghani
Published: September 2006

A comprehensive model is presented for predicting the rate of steel corrosion in concrete structures and the consequent formation and propagation of cracks around the steel reinforcement. The corrosion model considers both the initiation and the propagation stages of corrosion. Processes commencing in the initiation stage, such as the transport of chloride ions and oxygen within the concrete and variation in temperature and moisture, are assumed to continue in the propagation stage while active corrosion is occurring contemporaneously. This allows the model to include the effects of changes in exposure conditions on the corrosion rate and the effects of the corrosion reactions on the transport properties of concrete. The corrosion rates are calculated by applying the finite-element solution of the Laplace equation for electrochemical potential, with appropriate boundary conditions. Because these boundary conditions are nonlinear, a nonlinear solution algorithm is used. The results of the analysis are compared with available test data, and the comparison is found to be satisfactory. Key words: reinforced concrete, steel corrosion, finite-element modelling, durability.
Integration of stochastic deterioration models with multicriteria decision theory for optimizing maintenance of bridge decks
Authors: Morcous George , Lounis Zoubir
Published: September 2006

This paper presents a new approach to optimizing the maintenance of concrete bridge decks. This approach combines a stochastic deterioration model and a multiobjective optimization model. The stochastic deterioration model is based on the first-order Markov chain, which predicts the probabilistic time variation of bridge deck conditions. The multiobjective optimization model takes into account two important and conflicting criteria: the minimization of maintenance costs and the maximization of the network condition. This approach achieves the best compromise between these competing criteria while considering the uncertainty in bridge deck deterioration. The feasibility and capability of the proposed approach are demonstrated with field data for a sample network of bridge decks obtained from the Ministère des Transports du Québec database. This example illustrates the effectiveness of the proposed approach in determining the optimal set of maintenance alternatives for reinforced concrete bridge decks when two or more relevant optimization criteria are taken into consideration.Key words: concrete bridge deck, maintenance management, multicriteria optimization, Markov chain, deterioration model.
Use of wet cellulose to cure shotcrete repairs on bridge soffits. Part 1: Field trial and observations
Authors: Shehata Medhat , Navarra Mike , Klement Tom , Lachemi Mohamed , Schell Hannah
Published: September 2006

This paper presents the results obtained from a research project that focused on investigating the feasibility of using cellulose fibers to cure bridge soffit repairs. The use of cellulose as a curing method involves spraying wet cellulose on the freshly applied shotcrete. By adhering to the shotcrete, the wet cellulose maintains the relative humidity within the shotcrete above the level required to sustain hydration of the cementing materials. Twelve 1000 mm × 1000 mm × 130 mm panels were prepared using two types of shotcrete materials and cured using either air curing, curing compound, misting and curing compound, or cellulose. The results showed that the cellulose could be applied to shotcrete in an overhead position and remained adhered to the shotcrete for 28 days. At the end of the curing period, the cellulose was easily removed from the shotcrete surface by means of a hand shovel. Cellulose-cured panels showed the least evidence of surface cracking. Also, the use of cellulose did not have any negative effects on the temperature of the shotcrete.Key words: bridge repair, shotcrete, silica fume, accelerator, polypropylene fibers, curing, cellulose, heat of hydration, adhesion.
Use of wet cellulose to cure shotcrete repairs on bridge soffits. Part 2: Laboratory testing and analysis
Authors: Shehata Medhat , Navarra Mike , Klement Tom , Lachemi Mohamed , Schell Hannah
Published: September 2006

This paper reports results of an experimental program conducted to investigate the quality of shotcrete cured by wet, sprayed-on cellulose fibers. The program also investigated the quality of shotcrete containing accelerator. Both field and laboratory samples were prepared and cured using air-curing, curing compound, misting and curing compound, or cellulose. At the end of the curing period, cores were collected from the test panels and tested. The results showed that the effects of curing are noticeable mainly at the top 15 mm of the shotcrete surface. Within this part of the shotcrete, cellulose-cured panels showed an enhanced pore structure compared to samples cured using traditional curing methods, as reflected by mercury intrusion porosimetry and sorptivity test results. The quality of the surface of cellulose-cured shotcrete was significantly enhanced when the additives added to commercially available cellulose to improve its fire resistance were eliminated. Adhesive added to improve bonding of cellulose fibers to the shotcrete surface did not have a negative effect on the surface of the shotcrete. Laboratory-prepared samples showed evidence that cellulose curing reduces shrinkage cracking. The use of accelerator was found to adversely affect the strength and durability of the shotcrete.Key words: bridge repair, shotcrete, accelerator, salt scaling, curing, cellulose, permeability, sorptivity, pore structure, degree of hydration.
Behavior of branch-rotated T joints with cold-formed square hollow sections
Authors: Bae Kyu-Woong , Park Keum-Sung , Choi Young-Hwan , Moon Tae-Sup , Stiemer S F
Published: September 2006

An experimental investigation of branch-rotated T joints was carried out in which the branch was rotated by 45° with respect to its longitudinal axis. The main experimental parameters were the ratio of the width of the branch to the width of the chord, β′, with 0.38 ≤ β′ ≤ 1.00, and the ratio of the width of the chord to the thickness of the chord, 2γ, with 16.7 ≤ 2γ ≤ 33.3. Experimental results from 27 specimens showed that the ultimate strength increases and the failure mode changes under compression loading due to the rotated branch. The failure modes were out-of-plane bending yielding of the upper flange of the chord for β′ ≤ 0.85 and buckling of the chord web for 0.85 < β′ ≤ 1.00. Theoretical analysis was then carried out to compute the ultimate strength using a yield-line model for β′ ≤ 0.85 and web buckling model for β′ =  1.00. Linear interpolation was used for 0.85 < β′ < 1.00. Design formulas are presented for estimating the strength of T joints with a rotated branch.Key words: hollow structural section, truss T joint connections, yield-line instability, chord web instability, design equations.
An experimental study of flow into orifices and grating inlets on streets
Authors: Mustaffa Z , Rajaratnam N , Zhu David Z
Published: September 2006

Findings are described from a laboratory-scale model of flow through orifices on manhole covers and through three types of grating inlets used by the City of Edmonton. The results demonstrated that the flow through these orifices can be calculated using an orifice equation with a coefficient of discharge equal to 0.616 in a ponding situation but decreasing with an increase in the Froude number of the flow. The roughness of the manhole cover was found to slow down this reduction. For the three gratings, the inflow can be calculated with an orifice type of equation when the gratings are submerged. The discharge coefficient in this equation is approximately constant for two of the gratings and decreases somewhat with an increase in the Froude number of the flow for the third grating if the specific energy of the approaching flow is used as the length scale.Key words: street inlet, street hydraulics, grating inlet, orifice flows.
Light-gauge steel-frame  wood structural panel shear wall design method
Authors: Branston A E , Boudreault F A , Chen C Y , Rogers C A
Published: September 2006

Design guidelines for laterally loaded (wind and seismic) light-gauge steel-frame  wood structural panel shear walls are currently unavailable in Canadian standards and codes. A research project was initiated at McGill University in 2001 with the objective of developing a shear wall design method that could be used in conjunction with the 2005 National Building Code of Canada (NBCC). An extensive program of tests was first carried out to establish a database of shear wall information. The equivalent energy elasticplastic (EEEP) analysis approach was then chosen to derive key design parameters for the shear walls, including nominal shear strength, elastic stiffness, overstrength, and ductility. This paper presents the development of the proposed design method, the resulting nominal strength and unit elastic stiffness values according to typical perimeter fastener schedules and sheathing type, and the calibration of a resistance factor to the 2005 NBCC wind loads. Overstrength values used for a capacity-based seismic design approach and factors of safety for wind loading are also provided.Key words: shear wall, light-gauge steel, wood structural panel, earthquake, wind, design.
Determination of transport parameters for heavy metal in residual compacted soil using two methodologies
Authors: Azevedo Izabel Christina Duarte , Nascentes Cleidimar Rejane , Matos Antonio Teixeira de , Azevedo Roberto Francisco de
Published: September 2006

Values of the hydrodynamic dispersion coefficient and retardation factor obtained using the traditional and cumulative mass methods of column test analysis for zinc, manganese, and cadmium in a compacted soil are compared. The soil under study is from the B horizon of a residual gneissic tropical soil used for construction of the liner for the sanitary landfill in the District of Visconde do Rio Branco, Minas Gerais (MG), Brazil. To evaluate the behavior of landfill leachate heavy metals through the soil, soil column tests were performed on samples of compacted soil. A computational program that uses an optimization procedure to generate values of the hydrodynamic dispersion coefficient and retardation factor was developed to facilitate interpretation of the results obtained by the cumulative mass method. Values of the retardation factor and hydrodynamic dispersion coefficient were not influenced by the method of determination, even when a reduced number of effluent samples was used by the cumulative mass method. The use of the cumulative mass method, based on a reduced number of pore volumes, reduces the time and cost involved in the tests.Key words: heavy metals, column test, cumulative mass method.
Durability and sustainability of infrastructure — a state-of-the-art report
Authors: Mirza Saeed
Published: September 2006

This paper discusses the basic concepts involved in infrastructure, durability, and sustainability. At present, infrastructure facilities are designed and constructed on the basis of direct costs only, without explicit consideration of maintenance and depreciation over its service life as in other industries. Proper design, operation, and management of infrastructure must deal with every facet of its service life, ranging from conception, feasibility studies, design, construction, operation, maintenance, repair and rehabilitation, and finally decommissioning and disposal of the system after it has outlived its useful life. Every step of these considerations must be guided by overall socioeconomic and environmental concerns; in summary, they must be guided by the principles of sustainable development, which embrace the issue of embodied energy in the materials, construction, and both initial and recurring maintenance. The degradation of the performance of Canada's infrastructure over the past few decades is reviewed, along with the consequences of proper or deferred maintenance and their impact on Canada's infrastructure deficit. The roles of the civil engineering profession, including education and training, and those of the public and private sectors are discussed briefly.Key words: depreciation, design, deterioration assessment, durability, durability audits, infrastructure surveys, maintenance, life-cycle performance and costs, repair and rehabilitation, sustainability.
Passive treatment of municipal landfill leachate in a granular drainage layer
Authors: Ruiz E , Fleming I R , Putz G J
Published: September 2006

This paper describes a laboratory investigation that simulates in situ treatment of leachate representative of that generated by a municipal solid waste (MSW) landfill. The objective of the investigation is to demonstrate that recycle of leachate and treatment within a leachate collection system (LCS) coupled with a nitrification reactor can provide significant decreases in leachate chemical oxygen demand (COD) and ammonia concentration. In the investigation five 15 cm (6 in.) diameter polyvinyl chloride (PVC) columns were packed with drainage media of various sizes consisting of natural gravel and (or) crushed concrete (washed and screened). Geotextiles were placed between the various media as filterseparators and to promote bacterial growth. Synthetic leachate was continuously fed into the top of each column and recirculated from the bottom at rates representative of operating field conditions. For each column, effluent was discharged to a nitrification reactor before recirculation. The tests were conducted under anaerobic and unsaturated conditions in the columns. The results obtained from the experiment show that in situ treatment at landfills using this approach is viable. A 97% decrease in COD and about 98% conversion of the ammonia to nitrogen gas was observed. The denitrification process did not significantly inhibit COD depletion or methane production. Further, the biogas produced contained only a small fraction of CO2, which could suggest a potential benefit in terms of decreasing the potential of clogging in the LCS and extending the service life of a landfill gas (LFG) collection network by generating a less corrosive environment.Key words: leachate treatment, chemical oxygen demand (COD) removal, nitrification, denitrification, biogas production, sanitary landfill.
Long-term prevention of organics dissolution from wastewater sludge treated with coal fly ash
Authors: Kuchar Dalibor , Bednarik Vratislav , Vondruska Milan , Kojima Yoshihiro , Onyango Maurice S , Matsuda Hitoki
Published: September 2006

The present study is concerned with stabilization of wastewater sludge mixed with coal fly ash and carbon black for a treatment period ranging from 28 d to 2.5 years. To evaluate the stabilization degree of treated sludge, the dissolved organic carbon (DOC) of leachate from the sludge was measured. Results demonstrated that after 28 d of treatment, the DOC of the leachate was reduced from 2320 to 86 mg/L, when sludge was mixed with 45 wt% coal fly ash and 3 wt% carbon black. The DOC of the leachate after 1 year was higher than that after 28 d of treatment, which might be caused by decomposition of organic materials in the initial sludge. However, there was no appreciable difference in DOC values between 1 and 2.5 years treatment. It was concluded that organic materials were prevented from leaching out from the sludge by hydration products formed by coal fly ash and by carbon black adsorption. Key words: coal fly ash, wastewater sludge, carbon black, dissolved organic carbon, long-term stabilization.
Direct detection of methylphenylgermylene and 1,2-dimethyl-1,2-diphenyldigermene — Kinetic studies of their reactivities in solution
Authors: Leigh William J , Dumbrava Ileana G , Lollmahomed Farahnaz
Published: September 2006

Photolysis of 1,3,4-trimethyl-1-phenylgermacyclopent-3-ene (5) in hydrocarbon solvents containing isoprene, methanol, or acetic acid affords 2,3-dimethyl-1,3-butadiene (DMB) and the expected trapping products of methyl phenylgermylene (GeMePh) in chemical yields exceeding 90%. The germylene has been detected in hexane solution by laser flash photolysis as a short-lived species (τ ~ 2 µs) exhibiting a UV-vis absorption spectrum centered at λmax = 490 nm. It decays with second-order kinetics and a rate constant close to the diffusion-controlled limit, with the concomitant growth of a second longer-lived transient (λmax = 420 nm) that is assigned to a mixture of (E)- and (Z)-1,2-dimethyl-1,2-diphenyldigermene (4). Absolute rate constants have been determined for the reactions of the germylene with primary and tertiary amines (n-BuNH2 and Et3N, respectively), acetic acid (AcOH), a terminal alkyne and alkene, isoprene, DMB, CCl4, and the group 14 hydrides Et3SiH and Bu3SnH. GeMePh is slightly more reactive than GePh2 towards all the reagents studied in this work; both are significantly less reactive than GeMe2 toward the same substrates. Absolute rate constants for the reactions of 4 have also been measured or assigned upper limits in every case and are compared to previously reported values for tetraphenyl- and tetramethyl-digermene with the same reagents.Key words: germylene, digermene, kinetics, laser flash photolysis, germirane, germirene, vinylgermirane, complex, UV–vis spectrum, insertion, addition.
Tris(biimidazolato)chromium(III) as a building block for hydrogen-bonded supramolecular assemblies
Authors: Gruia Letitia M , Rochon Fernande D , Beauchamp André L
Published: September 2006

The trischelate [Cr(H2biim)3](NO3)3complex of 2,2′-biimidazole (H2biim) was obtained by reacting CrCl3·3THF with [Ag(H2biim)](NO3) in methanol. In the solvent-free material, each ligand forms two N-H···O bonds to a nitrate ion and generates locally neutral [Cr(H2biim)3](NO3)3units. A methanol solvate was also obtained in which intermolecular interactions involve optimal use of the hydrogen-bonding ability of the [Cr(H2biim)3]3+cations, NO3–anions, and methanol molecules. In both cases, there is no long-range regular organization of the complex units. Deprotonation of [Cr(H2biim)3](NO3)3with NaOCH3yielded neutral Cr(Hbiim)3. Its powder pattern is similar to that of Ru(Hbiim)3, suggesting that it also consists of mutually perpendicular interlocked honeycomb sheets. Recrystallization by slow diffusion of diisopropyl ether into a methanol solution yielded a porous material of composition Cr(Hbiim)3·2.6C6H14O in which superposed honeycomb sheets create infinite channels (~13 Å diameter) filled with disordered solvent molecules. A totally different structure is adopted by the solvate Cr(Hbiim)3·C6H6·2H2O, where the benzene molecule is encapsulated in a cavity created by five complex molecules.Key words: chromium, biimidazole, supramolecular, crystal structure, hydrogen bonding.
Chemicals and energy from biomass
Authors: Lucia Lucian A , Argyropoulos Dimitris S , Adamopoulos Lambrini , Gaspar Armindo R
Published: September 2006

Approximately 89 million metric tonnes of organic chemicals and lubricants are produced annually in the United States (T.M. Carole, J. Pellegrino, and M.D. Paster. Appl. Biochem. Biotechnol. 115, 871 (2004)). The majority of these materials are fossil fuel based and may load the environment during use and at the end of their life cycle. Issues, such as disposal, pollution, and degradation, must be considered and weighed. As a result, the need to decrease pollution caused by petrochemical usage is currently impelling the development of green technologies. It is virtually inarguable that the dwindling hydrocarbon economy will eventually become unsustainable. The cost of crude oil continues to increase, while agricultural products see dramatic decreases in world market prices. These trends provide sufficient basis for renewed interest in the use of biomass as a feedstock and for the development of a carbohydrate-based economy as the logical alternative to fossil fuel resources.Key words: biomass, biochemicals, natural products, bioenergy.