Sustainability and cost-effectiveness of steel truss pedestrian bridges - A case study focusing on truss optimisation, deck systems and materials

ABSTRACT The interest to design more durable steel bridges has increased in the last few decades. This is mainly to minimize extra costs associated with steel corrosion that requires cumbersome preventive measures, such as painting and airtightness of welded closed-sections, and extensive repair and maintenance work. For the case of pedestrian bridges, it is fairly common to utilize steel trusses made with standard hollow profiles in carbon steel as primary load-bearing elements of the structure, thus posing a high risk for corrosion. Such risks, and consequently extra costs, could be significantly reduced by implementing stainless steel instead of carbon steel. Moreover, the deck could also be replaced by more lightweight and durable materials such as fiber reinforced polymer (FRP) deck systems. Both stainless steel and FRP would lower the amount of reparation work which decreases the future costs over the service life of a bridge. The initial cost could, however, be higher than for the conventional alternatives. This dilemma is investigated through a case study comparing five different truss bridge solutions made in either carbon steel, stainless steel or FRP, showing the effect on material-, cost- and environmental parameters when optimising the bridge designs. The aim is to compare and evaluate the outcome when using these new approaches, with the main objective to show differences gathered from the case study. The results show that the initial costs increase as the corrosion steel is replaced with stainless steel. This upgrade of material cost more than twice as much, while FRP as a substitute to the steel deck has similar investment price. But for the total cost over a 50-year long service life, these implementations are more cost efficient for this specific bridge. The overall cause for this outcome is mainly the expensive corrosion paint that’s required to be added to the carbon steel periodically. However, the carbon dioxide emissions are increased when looking at the production of stainless steel, but decreased for FRP due to the much lower weight compared to an ordinary steel deck. Also the investigated truss optimisation were shown to contribute to the material efficiency of the bridge with a truss configuration of different profiles between chords and diagonals. It is also shown that together with the new materials and design concepts, it is possible to achieve lighter, more durable and less costly pedestrian bridges

Grundvattenkemin tre år efter askgödsling på djupa torvmarker i Norrland

Askgödsling på torvmarker kan vara ett effektivt verktyg för att: i) öka trädens tillväxt, ii) tillföra näringsämnen och iii) motverka försurning. Föreliggande studie är inriktad mot kemiska effekter på grundvattnet. Syra/bas egenskaper, lösta näringsämnen, löst organiskt kol och halter av metylkvicksilver, studerades. Hur askgödsling påverkar koncentrationen av metylkvicksilver i grundvattnet inte tidigare undersökt och är därför ytterligare ett syfte med denna studie. I denna studie samlades totalt 44 grundvattenprover in från fem olika dränerade och beskogade torvmarker, belägna i norra mellan Sverige. Tre av torvmarkerna är näringsfattiga och två karaktäriseras som näringsrika. Prover från askgödslade ytor jämfördes med prover från kontrollytor, tre år efter askgödsling. De vattenkemiska parametrar som analyserades var: pH-värde, ANC, dominerande katjoner, ammonium, fosfat, anjoner till starka syror (inkl. nitrat), DOC och MeHg. Inga signifikanta skillnader fanns mellan ytor gödslade med 0, 5 och 10 ton aska, med avseende på: pH-värdet, ANC, dominerande katjoner, nitrat, fosfat, anjoner, DOC och MeHg. En svag signifikant skillnad återfanns för ammonium koncentrationen mellan askgödslade ytor och kontrollytor. Ammonium koncentrationen var lägre på ask gödslade ytor på tre av de fem torvmarkerna.Ash fertilization in peat lands can be an effective tool in order to: i) increase tree growth, ii) supplying nutrients and iii) counteract acidification. This study focus on effects of ash fertilization on groundwater quality. Acid/base properties, dissolved nutrients, dissolved organic carbon and concentrations of methyl mercury, were studied. How ash fertilization affect the concentrations of methyl mercury in the groundwater is not previously examined and are therefore a further object of this study. In this study 44 groundwater samples were collected from five different drained peat lands, situated in North Sweden and North Central Sweden. Three of the peatlands are considered to be nutrient poor and two are characterized as nutrient rich. The data was used to examine if groundwater quality from ash fertilized plots where different from control plots, three years after ash fertilization. The following water chemistry parameters where analyzed: pH-value, acid neutralizing capacity (ANC), major cations, ammonium, phosphate, strong acids anions inclusive nitrate, dissolved organic matter (DOC) and methyl mercury (MeHg). No significant differences were found between plots fertilized with 0, 5 and 10 ton ash, with respect to: the pH-value, the ANC, major cations, nitrate, phosphate, anions, DOC, MeHg. A weak significant difference where found in ammonium concentration between ash fertilized plots and control plots. Ammonium concentration was lower in ash fertilized plots at three of the five peatlands

Methylmercury in outlet from wetlands

Antropogen utsläpp av metylkvicksilver har i flera århundranden skett till atmosfären och vattensystem. I Sverige har ansträngningar för att minska kvicksilverutsläpp pågått sedan 1970-talet, men problem med kvicksilverförgiftad fisk kvarstår. Problemen med kvicksilver uppstår när grundformen syntetiseras till en organiskform, metylkvicksilver. Metylkvicksilver kan ta sig över cellmembran och stanna kvar i biologiskvävnad där den påverkar enzymatiska funktioner negativt. Studier för att utreda var omvandlingen till metylkvicksilver sker har identifierat våtmarker som källor. Tjerngren I. har samlat in data från åtta olika våtmarkstyper i hela Sverige och kom fram till att sju av de åtta våtmarkerna hade en nettoproduktion av metylkvicksilver. I samband med Tjerngrens våtmarksstudie samlades data från våtmarkernas utlopp in vid olika tidpunkter på året. Syftet med föreliggande studie är att utreda säsongsvariationerna för metylkvicksilver och andra vattenkemiska variabler i utloppsvattnet, samt undersöka om mätningar i våtmarkers utlopp säger något om metyleringsprocessen som sker i omgivande våtmark. Metylkvicksilverhalten i våtmarkernas utlopp var signifikant korrelerad till halterna i markens porvatten. Årscykeln för metylkvicksilverhalt och årscykeln för lufttemperatur följde varandra mycket nära under året, förutom under vintern. Det fanns ingen uppenbar tidsfördröjning mellan de två kurvorna. Halterna av metylkvicksilver och löst organiskt material (DOC) var starkt korrelerade och haltkurvorna följdes åt tämligen väl under perioden vår till höst. Sulfathaltens utveckling under vår och sommar var negativt korrelerad med metylkvicksilverhalten, sulfatet minskade när metylkvicksilvret ökade. Sammantaget tyder utvärderingen av vattenanalyserna på att processer som sker i våtmarken syns i dess utlopp.The problem of mercury occurs when the basic form is synthesized into an organic form, methylmercury. Methylmercury can cross the cell membrane where it affects the enzymatic functions negatively. Studies to investigate the conversion to methylmercury have identified wetlands as sources. Tjerngren. I collected data from eight different wetland types in Sweden and found that seven out of eight wetlands had a net production of methylmercury. In connection with Tjerngrens wetland study, data were collected from wetland outlets at different times of the year. The aim of the present study is to investigate the seasonality of methylmercury and other water chemistry variables in the wetland outlets and examine whether measurements of wetland outlet say something about the methylation reaction that is going on in the surrounding wetlands. Methylmercury concentrations in wetland outlets were significantly correlated with concentrations in soil pore water. Annual cycle for methylmercury concentrations and annual cycle of air temperature followed each other very closely during the year, except during the winter. There was no apparent time delay between the two curves. Concentrations of methylmercury and dissolved organic matter (DOC) were highly correlated and concentration curves followed each other fairly well during the period from spring to autumn. The development of the sulfate concentrations in spring and summer were negatively correlated with methylmercury, sulfate levels decreased when methylmercury levels increased. Overall, the evaluation of the water analyzes tells us that processes occurring in the wetland is visible in the outlet

Presence of CD8+ T Cells in the Ectocervical Mucosa Correlates with Genital Viral Shedding in HIV-Infected Women despite a Low Prevalence of HIV RNA–Expressing Cells in the Tissue

The female genital tract is a portal of entry for sexual HIV transmission and a possible viral reservoir. In this study, the ectocervical CD8+ T cell distribution was explored in situ and was related to expression of CD3 and HLA-DR and presence of HIV RNA. For this purpose, ectocervical tissue samples and genital secretions were collected from HIV-seropositive (HIV+) Kenyan female sex workers (FSWs) (n = 20), HIV-seronegative (HIV−) FSWs (n = 17), and HIV− lower-risk women (n = 21). Cell markers were assessed by in situ staining and by quantitative PCR. HIV RNA expression in tissue was analyzed by in situ hybridization, and viral shedding was assessed by quantitative PCR. The HIV+FSW group had a higher amount of total cells and CD8+, CD3+, and HLA-DR+ cells compared with the HIV−FSW group and HIV− lower-risk women. The majority of CD8+ cells were CD3+ T cells, and the numbers of CD8+ cells correlated significantly with plasma and cervical viral load. HIV RNA expression in situ was found in 4 of the 20 HIV+FSW women but did not correlate with cervical or plasma viral load. Thus, the HIV+ women displayed high numbers of CD8+, CD3+, and HLA-DR+ cells, as well as a limited number of HIV RNA+ cells, in their ectocervical mucosa; hence, this localization cannot be neglected as a potential viral reservoir. The elevated levels of CD8+ T cells may play a role in the immunopathogenesis of HIV in the female genital tract

Presence of CD8+ T Cells in the Ectocervical Mucosa Correlates with Genital Viral Shedding in HIV-Infected Women despite a Low Prevalence of HIV RNA–Expressing Cells in the Tissue

The female genital tract is a portal of entry for sexual HIV transmission and a possible viral reservoir. In this study, the ectocervical CD8+ T cell distribution was explored in situ and was related to expression of CD3 and HLA-DR and presence of HIV RNA. For this purpose, ectocervical tissue samples and genital secretions were collected from HIV-seropositive (HIV+) Kenyan female sex workers (FSWs) (n = 20), HIV-seronegative (HIV−) FSWs (n = 17), and HIV− lower-risk women (n = 21). Cell markers were assessed by in situ staining and by quantitative PCR. HIV RNA expression in tissue was analyzed by in situ hybridization, and viral shedding was assessed by quantitative PCR. The HIV+FSW group had a higher amount of total cells and CD8+, CD3+, and HLA-DR+ cells compared with the HIV−FSW group and HIV− lower-risk women. The majority of CD8+ cells were CD3+ T cells, and the numbers of CD8+ cells correlated significantly with plasma and cervical viral load. HIV RNA expression in situ was found in 4 of the 20 HIV+FSW women but did not correlate with cervical or plasma viral load. Thus, the HIV+ women displayed high numbers of CD8+, CD3+, and HLA-DR+ cells, as well as a limited number of HIV RNA+ cells, in their ectocervical mucosa; hence, this localization cannot be neglected as a potential viral reservoir. The elevated levels of CD8+ T cells may play a role in the immunopathogenesis of HIV in the female genital tract

In situ detection of Gag-specific CD8+ cells in the GI tract of SIV infected Rhesus macaques

<p>Abstract</p> <p>Background</p> <p>SIV and HIV predominantly replicate in lymphoid tissue, but the study of virus specific CD8⁺T cells in intact lymphoid tissue is difficult, as traditional <it>in situ </it>tetramer staining requires fresh tissue.</p> <p>Results</p> <p>In this report, we demonstrate a novel technique using Qdot 655-conjugated peptide-MHC multimers to directly visualize SIV specific cells in cryopreserved tissue biopsies from chronically SIVmac239 infected Rhesus macaques. Qdot 655 multimers showed similar sensitivity and specificity to APC-conjugated tetramers by flow cytometry analysis, but yielded ten-fold higher signal intensity when imaged by fluorescence microscopy. Using this technique, we detected CD8⁺T cells which recognize an immunodominant epitope (Gag CM9) in the spleen, lymph nodes, ileum and colon. In all these tissues, the Gag CM9 positive cells were mainly located in the extra follicular T cell zone. In the ileum and colon, we found Gag CM9 positive cells concentrated in Peyer's patches and solitary lymphoid follicles, a pattern of localization not previously described.</p> <p>Conclusions</p> <p>The use of Qdot multimers provide an anatomic and quantitative evaluation of SIV specific CD8⁺T cell responses in SIV pathogenesis, and may prove useful to studies of SIV specific CD8⁺T cell responses elicited by vaccines and other immunotherapies in the non-human primate model.</p

Gamma interferon induces different keratinocyte cellular patterns of expression of HLA-DR and DQ and intercellular adhesion molecule-I (ICAM-I) antigens

With indirect immunofluorescence techniques we demonstrated that recombinant gamma-interferon induced the expression of the class II antigens HLA-DR and HLA-DQ as well as intercellular adhesion molecule-1 (ICAM-1) on normal, cultured human keratinocytes grown in low-calcium, serum-free medium. Each antigen displayed a distinctive cellular staining pattern. HLA-DR was strongly localized to perinuclear zones with intense cell surface expression; HLA-DQ displayed a perinuclear accentuation, but with minimal cell surface staining, and ICAM-1 was strongly expressed in a diffuse cytoplasmic pattern with intense cell surface expression. Keratinocytes grown in medium supplemented with 10% fetal calf serum underwent differentiation, with a diminished expression of all three antigens as compared to those grown in low-calcium, serum-free medium. These results confirm that gamma interferon can differentially regulate HLA-DR nd HLA-DQ expression; that there are probably different biochemical metabolic pathways by which these three molecules are expressed on keratinocytes, and that the expression is also a function of the degree of keratinocyte differentiation. The strong cell surface expression of ICAM-1 is suggested to be of major importance as the recognition molecule, by which T cells bind to gamma interferon exposed keratinocytes, and suggests and integral role for this molecule in epidermal lymphocyte trafficking.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74686/1/j.1365-2133.1989.tb07759.x.pd

CD49a Expression Defines Tissue-Resident CD8+ T Cells Poised for Cytotoxic Function in Human Skin

Tissue-resident memory T (Trm) cells form a heterogeneous population that provides localized protection against pathogens. Here, we identify CD49a as a marker that differentiates CD8(+) Trm cells on a compartmental and functional basis. In human skin epithelia, CD8(+)CD49a(+) Trm cells produced interferon-γ, whereas CD8(+)CD49a(−) Trm cells produced interleukin-17 (IL-17). In addition, CD8(+)CD49a(+) Trm cells from healthy skin rapidly induced the expression of the effector molecules perforin and granzyme B when stimulated with IL-15, thereby promoting a strong cytotoxic response. In skin from patients with vitiligo, where melanocytes are eradicated locally, CD8(+)CD49a(+) Trm cells that constitutively expressed perforin and granzyme B accumulated both in the epidermis and dermis. Conversely, CD8(+)CD49a(–) Trm cells from psoriasis lesions predominantly generated IL-17 responses that promote local inflammation in this skin disease. Overall, CD49a expression delineates CD8(+) Trm cell specialization in human epithelial barriers and correlates with the effector cell balance found in distinct inflammatory skin diseases

Interplay between HIV-1 infection and host microRNAs

Using microRNA array analyses of in vitro HIV-1-infected CD4+ cells, we find that several host microRNAs are significantly up- or downregulated around the time HIV-1 infection peaks in vitro. While microRNA-223 levels were significantly enriched in HIV-1-infected CD4+CD8− PBMCs, microRNA-29a/b, microRNA-155 and microRNA-21 levels were significantly reduced. Based on the potential for microRNA binding sites in a conserved sequence of the Nef-3′-LTR, several host microRNAs potentially could affect HIV-1 gene expression. Among those microRNAs, the microRNA-29 family has seed complementarity in the HIV-1 3′-UTR, but the potential suppressive effect of microRNA-29 on HIV-1 is severely blocked by the secondary structure of the target region. Our data support a possible regulatory circuit at the peak of HIV-1 replication which involves downregulation of microRNA-29, expression of Nef, the apoptosis of host CD4 cells and upregulation of microRNA-223