Effect of Deformation Height and Spacing on Bond Strength of Reinforcing Bars

The effect of deformation pattern on bond strength is studied using 1-in. (25-mm) diameter machined bars with deformation heights of 0.05, 0.075, and 0.10 in. (1.27, 1.91, and 2.54 mm) and deformation spacings ranging from 0.26 to 2.2 in. (6.7 to 56 mm). The combination of rib height and spacing produce relative rib areas (ratio of projected rib area normal to bar axis to product of nominal bar perimeter and center-to-center rib spacing) of 0.20, 0.10, and 0.95 for each deformation height. Conventional reinforcing bars, with a relative rib area of 0.07, are also studied. The effect of deformation pattern is evaluated using beam-end specimens with varying degrees of confinement provided to the test bars. Degrees of confinement are: 1) 2-in. (51-mm) cover without transverse stirrups, 2) 2-in. (51-mm) cover with confining transverse stirrups, and 3) 3-in. (76-mm) cover without confining transverse stirrups. Bars with 2-in. (51-mm) cover have an initial unbonded length of -1/2 in. (13 mm) and a bonded length of 12 in. (305 mm). Bars with 3-in. (76-mm) cover have an initial unbonded length of 4 in. (102 mm) and a bonded length of 8-1/2 in. (216 mm). The bond force-slip response of reinforcing bars is a function of the relative rib area of the bars, independent of the specific combination of rib height and rib spacing. Under all conditions of bar confinement, the initial stiffness of load-slip curves increases with an increase in the relative rib area. Under conditions of relatively low confinement, in which bond strength is governed by splitting of the concrete, bond strength is independent of deformation pattern. Under conditions in which additional bar confinement is provided by transverse reinforcement or higher cover, bond strength increases compared to the bond strength of bars with less confinement. The magnitude of the increase in bond strength increases with an increase in the relative rib area.Reinforced Concrete Research Counci

Effect of Deformation Height and Spacing on Bond Strength of Reinforcing Bars

The effect of deformation pattern on bond strength is studied using 1 in. diameter machined bars with deformation heights of 0.05, 0.075, and 0.10 in. and deformation spacings ranging from 0.26 in. to 2.2 in. The combinations of rib height and spacing produce relative rib areas (ratio of projected rib area normal to bar axis to product of nominal bar perimeter and center-to center rib spacing) of 0.20, 0.10, and 0.05 for each deformation height Conventional reinforcing bars, with a relative rib area of 0.07, are also studied. The effect of deformation pattern is evaluated using beam-end specimens with varying degrees of confinement provided to the test bars. Degrees of confinement are: 1) 2 in. cover without transverse stirrups, 2) 2 in. cover with confining transverse stirrups, and 3) 3 in. cover without confining transverse stirrups. Bars with 2 in. cover have an initial unbonded length of lh in. and a bonded length of 12 in. Bars with 3 in. cover have an initial unbonded length of 4 in. and a bonded length of 81h in. The bond force-slip response of reinforcing bars is a function of the relative "rib area of the bars, independent of the specific combination of rib height and rib spacing. Under all conditions of bar confmement, the initial stiffness of load-slip curves increases with an increase in the relative rib area. Under conditions of relatively low confinement, in which bond strength is governed by splitting of the concrete, bond strength is independent of deformation pattern. Under conditions in which additional bar confinement is provided by transverse reinforcement or higher cover, bond strength increases compared to the bond strength of bars with less confmement. The magnitude of the increase in bond strength increases with an increase in the relative rib area

RESPONSE OF FERRITIN TO OXIDATIVE STRESS IN RHEUMATOID ARTHRITIS

 Objective: Rheumatoid arthritis (RA) has been categorized as a disease of connective tissue and an autoimmune disease but was not, until recently recognized as a disease due to oxidative stress. Ferritin, an iron binding protein is involved in intracellular storage of iron pool, which play a central role in the maintenance of delicate intracellular iron balance. The ability of cells to induce rapid ferritin synthesis prevents the effect of free radical damages to cellular components. The objective of the current study is to evaluate the serum ferritin level and its response to oxidative stress in rheumatoid arthritis.                                                                                               Methods: The study group included 50 patients with RA and 50 age and sex matched healthy controls. The serum ferritin, albumin, hsCRP, Malondialdehyde (MDA) and Vitamin C levels were estimated.                                                                                                                             Result: Serum ferritin, hsCRP, and MDA levels were found to be significantly increased in RA patients, whereas Vitamin C level was significantly decreased in RA patients when compared to controls.                                                                                                                              Conclusion: The study conclude that rise in serum ferritin, an acute phase reactant is due to inflammatory response to the rising oxidative stress in RA.Key words: Rheumatoid arthritis, Ferritin, Malondialdehyde (MDA

Heavy Metals Accumulation by Indigenous Plants Growing in Contaminated Soil in a Gold Mining Area in Ghana

Phytoremediation is an environmentally friendly, low cost biotechnological process that is fast gaining prominence in the cleaning of contaminated soils in the tropics. The accumulative potential of indigenous or native plants for heavy metals in mine tailings at the Storage Facility of the Chirano Gold Mine Limited, Ghana was investigated. Plant species were sampled in five plots, each 32 m2. Samples of plants were harvested and separated into roots and shoots and the corresponding rhizospheric soil samples collected. They were analysed for the total concentrations of heavy metals; Arsenic (As), Cadmium (Cd) and Zinc (Zn) using Atomic Absorption Spectrophotometer. Bioavailable fractions of studied metals in the soil samples were determined with the formation of metal complex with Ethylenediaminetetraacetic acid and ammonium acetate reagents. The hyper-accumulation potential and mobility of heavy metals within the plants were determined from the bioaccumulation and translocation factors. Differences in mean concentrations of heavy metals in the plants (shoot, root and whole) were separated using Tukey B Analysis of Variance, SPSS version 20, at significant level of p < 0.05. The mean concentrations of total and bioavailable As, Cd, and Zn in the soil samples varied with Zinc being most predominant (13.20 mg/kg). However, As was the most available with 39% bioavailability. The soil elemental concentrations of As (3.0 mg/kg), Cd (0.29 mg/kg) and Zn (13.20 mg/kg) were below the WHO recommended standards of 12 mg/kg, 1.4 mg/kg and 200 mg/kg for As, Cd and Zn respectively. The concentrations of all metals in the plant organs varied between species. In all plant species Zinc was the most accumulated heavy metal, recording the highest level of accumulation (135.76 mg/kg) in the root of Euphorbia heterophylla. Bioaccumulation factor as expressed by total and bioavailable metal concentrations in soil indicate that all the plant species demonstrate good hyperaccumulation and phytostabilisation potential for Zn and Cd whilst 13 and 8 plant species demonstrate good phytoextraction potential for As. The translocation factor indicate that 8 plant species are good phytostabilisers for Zn, 7 plant species for Cd and 10 plant species for As. The accumulative and phytostabilisation potential of these plant species provide useful information about their selective exploitation for effective phytoremediation of the tailings dam at Chirano Gold Mine. Keywords: phytoremediation, heavy metal, hyperaccumulation, phytostabilisation, indigenous plants, bioavailable

Evaluation of Biochemical Toxicity and Antioxidant Properties of Pioglitazone on Albino Wistar Rats

Pioglitazone is one of the thiazolidinedione anti-diabetic drugs which have been used for the treatment of non-insulin dependent diabetes mellitus. This study aims at investigating the biochemical effects and safety of pioglitazone (PIO) at various concentrations in female Wistar rats. A total of 28 rats were randomly divided into four groups of seven animals each. Groups 1-4 were given 0.5 mL kgG1 b.wt., dayG1 of distilled water as normal control; 15, 30 and 45 mg kgG1 b.wt., dayG1 of PIO, respectively as treatment groups 2, 3 and 4, respectively for 28 days. Using standard biochemical kits and reported chemical procedures, plasma biochemical parameter and organ lipid peroxidation effects were determined in all the groups. There was significant increase (p<0.05) in plasma total protein concentration of group 3 and 4 in comparison with control. There was also significant (p<0.05) reduction in total and LDL cholesterols in PIO-treated groups and concentration of TBARS was reduced in the liver and heart of PIO-treated groups in comparison with normal control. There was no significant alteration in the concentrations and activities of liver and kidney function markers of PIO treated groups in comparison with normal control groups. Pioglitazone at highest concentration of 45 mg kgG1 b.wt., for the duration of 28 days did not elicit any measurable biochemical toxicity on non-diabetic rat mode

Phytochemical and Mineral Analysis of 12 Cultivated Oyster Mushrooms (Pleurotus Species)

Phytochemical analysis was conducted on methanolic extracts of 4 oyster mushrooms species (Pleurotus pulmonarius, P. ostreatus, P. sapidus and P. citrinopileatus) made up of 12 different strains. The study was carried out to determine the contents of total phenol and flavonoids, beta carotene and lycopene, antioxidant properties and concentrations of mineral elements and heavy metals in the macrofungi methanolic extracts. Total phenolic contents ranged from 1.48 µg GAE/g to 3.58 µg of GAE/g with a mean of 2.5 µg of GAE/g and 0.36 coefficient of variation. The 12 strains were statistically different from each other. Total flavonoid content varied from 0.20 µg of RE/g to 2.03 µg of RE/g of dry weight of extracts with a grand mean of 0.85 µg of RE/g and 9.89 coefficient of variation. There was significant difference among the 12 mushroom strains (P&lt;0.001). Beta carotene content varied from 0.60 to 11.46 µg/g and that of lycopene varied from 0.04 to 4.28 µg/g. The IC50 values ranged between 43.21 µg/ml and 52.03 µg/ml, the inhibition of DPPH radical by P. sapidus strain PSC-1 and P. ostreatus strain POA-5 exhibited the highest activity. Significant difference was observed among the strains. Mg content varied from 660.0 mg/kg to 1993.7 mg/kg, Fe content ranged from 349.0 mg/kg to 1374.0 mg/kg and could not be detected in P. ostreatus strain POA-7.  Ca content ranged from 22.0 mg/kg to 415.3 mg/kg, Mn content varied from 10.7 mg/ kg to 48.3 mg/kg and was below detection in the six strains of P. pulmonarius strain PPA-2, P. ostreatus strain POA-5, P. ostreatus strain POA-6, P. ostreatus strain POA-7, P. ostreatus strain POA-10 and P. ostreatus strain POA-13. Cu content ranged from 15.3 mg/kg to 23.7 mg/kg but below detection in two strains P. ostreatus strain POA-6 and P. ostreatus strain POA-10. Zn content varied from 189.7 mg/kg to 411.3 mg/kg. Ni content varied from 175 mg/kg to 296.7 mg/kg, Cd content ranged between 57.7 mg/kg and 106.3 mg/kg, Pb content varied from 13.0 mg/kg to 230.7 mg/kg. Cr content ranged between 17.7 mg/kg and 124 mg/kg. All the Pleurotus strains showed appreciable levels of antioxidant activities and can be promoted as natural antioxidant preference in food and pharmaceutical Keywords: 1,1-diphenyl-1-picrylhydrazyl (DPPH) assay, total flavonoids content, total phenolics content, beta carotene content, lycopene content, mineral elements, heavy metal

Palaces for the People: Mapping Public Libraries\u27 Capacity for Social Connection and Inclusion

Public libraries are trusted community hubs that foster connections with individuals of different socioeconomic statuses; ages; ethnic, linguistic, religious, and cultural backgrounds; and sexual and gender identities. Located in diverse settings, library branches offer resources and programs that meet the specific needs of their communities who are navigating the effects of our increasingly asocial society. Libraries have been shown to cater to individuals contending with higher levels of social isolation and loneliness, as well as increased rates of mental illnesses and antisocial behaviours. The shift to online environments during COVID-19 has exacerbated feelings of disconnection. During these times of change, public libraries facilitate resilience, helping communities withstand and adapt to difficult circumstances. While several individual studies have separately examined libraries’ outreach efforts, what remains unknown is the broader knowledge landscape regarding public library practices, spaces, and activities that collectively create and reinforce social connections in an increasingly asocial society. We examined scholarly literature to answer the following questions to to bridge existing knowledge gaps: How do public libraries help patrons create or maintain connections in their communities? What population groups are included in public library research and in what ways are they differently impacted by public library services, materials, and/or spaces? How are public library virtual programming and services (especially prominent during COVID-19) changing the ways in which patrons engage with public libraries? In what ways does the Canadian public library research landscape compare or differ from that in European and Australasia countries, and what lessons can we glean from these differences?Underlying a majority of the included articles is an acknowledgement that the role of public libraries is changing, from operating as information repositories to now also operating as community hubs. The ways in which public library systems and branches engage with their communities and patrons are therefore also shifting. Focusing in particular on the current state of public library-related research knowledge on issues related to growing feelings of disconnection, isolation and loneliness, articles explored the multiple ways in which public libraries afford connection for and among their patrons. Public libraries draw on their spaces, their staff, their collections and materials, their programs, and relationships with community organizations to bolster feelings of connection. Given the distribution of public libraries across the country, in urban and rural locales and in neighbourhoods of high and low poverty, the ways in which public libraries both connect with and provide connection manifest differently depending on their contexts. Research on this topic is indicative of the many different population groups that public libraries engage with and support on a daily basis. Research focuses on a myriad of population groups, including: children, youth, older adults, parents, unhoused populations, differently abled individuals, immigrants and non-permanent residents, among others. This breadth of population groups, each with their own unique circumstances, needs, and expectations, is indicative of the range of factors and contexts library workers need to consider and incorporate in their programs, collections, arrangement of physical and virtual spaces, and administration. Across published research, public libraries fostered connection through the following means: Encouraging feelings of belonging Creating connections through technology Reinforcing cultural identities Creating safe physical spaces Addressing issues of accessibility Creating new educational programming Creating new recreational/social programmin