Capacity Evaluation of a Severely Distressed and Deteriorated 50-Year-Old Box Beam with Limited Data

In 2005, 15 adjacent box-beam bridges were randomly selected and inspected to document their performance with consideration of the evolving design procedures. Longitudinal cracking along the soffit of several fascia beams was documented. After evaluating inspection data, the bridge engineer recommended the replacement of a severely distressed fascia beam from the Hawkins Road Bridge in Jackson County, Michigan. The beam was salvaged and the capacity was evaluated through load testing. The remaining prestress was 75% of the initial prestress, which is 5% less than the final prestress used for the design. Concrete modulus of elasticity was evaluated as 35.4?GPa and the nominal compressive strength as 54.4?MPa. Analysis of load test data indicated that a bridge with the beam in this distressed state is safe to operate. This is assuming that the transverse connectivity between the beams is sufficient for load distribution as envisioned in the design. The importance of identifying concealed corrosion, and quantifying material properties and load distribution is highlighted in this paper.     

Dynamic modelling of a proton exchange membrane (PEM) electrolyzer

This paper describes a dynamic model for PEM electrolyzer based on conservation of mole balance at the anode and the cathode. A further feature of the model is it includes water phenomena, electro-osmotic drag and diffusion, through the membrane. The model considers PEM electrolyzer to be composed of four ancillaries: anode, cathode, membrane and voltage ancillary. Additionally, hydrogen storage dynamics is presented. The developed model is suitable for determining control strategy that will ensure efficient and reliable operation of the electrolyzer. Moreover, the dynamic model can be integrated with renewable energy systems models to design, analyze and optimize sustainable energy systems. The study illustrates the dynamic interactions within a PEM electrolyzer and shows the necessity of the proposed approach of separate ancillaries.     

Voltammetric characterization of selective potassium ion transfer across micro-water/1,2-dichloroethane interface facilitated by a novel calix[4]arene derivative

In this study, transfer reactions of alkali and alkaline-earth metal ions across a micro-water/1,2-dichloroethane (1,2-DCE) interface facilitated by a novel calix[4]arene derivative, 5,11,17,23-tetra-tert-butyl-25,27-bis(2′amino-methylpyridine)-26,28-dihydroxy calix[4]arene (APHC4), were investigated by cyclic and differential pulse voltammetry techniques. Well-defined voltammetric behavior was obtained only for K⁺ ion among the used metal ions. The electrochemical data were used to determine the stoichiometry and the appropriate association constant of the occurring complex between K⁺ ion and APHC4. The obtained steady-state voltammograms indicated that the facilitated transfer process occurs with a TIC/TID mechanism according to 1:1 stoichiometry. The logarithm of the association constant () of K(APHC4)⁺ complex in the DCE phase was calculated to be 6.32. Also, the availability of the facilitated transfer for the design of an amperometric screening sensor for K⁺ ion was evaluated in the range of 50–500 μmol dm⁻³.     

Simultaneous evaluation of effective diffusion coefficients of the substrates in a biofilm with a novel experimental method

In this study, a pure culture of Zoogloea ramigera was grown as a film on active carbon particles in a differential fluidized bed biofilm reactor (DFBBR) as a novel experimental system for the application of diffusion-reaction models. The effective diffusion coefficients of the essential substrates; glucose, ammonium ion and oxygen in the active biofilm were simultaneously calculated. The values of effective diffusion coefficients in the active biofilm to those in water varied between 13–34, 48–96 and 28–48% for glucose, ammonium ion and oxygen, respectively, at different biofilm densities, which is in fair agreement with the literature.     

Prevention of brown discoloration in European oakwood occurring during kiln drying by a vacuum process: Colorimetric comparative study with a traditional process

The efficiency of two kiln drying processes on brown discoloration developments ofQuercus robus (L) andQuercus petraea (Lieb) was studied. A traditional atmospheric pressure system, was compared with other using vacuum and super heated steam. 103 green boards from three different trees were used. After each cycle (6), we analysed and compared the color of the boards using a spectrocolorimeter fitted with the CIELAB analysis. With the traditional system (in moist condition) we obtained 100% brown discoloration, in contrast to vacuum and super heating which did not develop brown discoloration. The brown discoloration is characterised by a decrease in lightness (-6 to-8 units) and color angle (-1 to-2 units) compared to non discolored wood. The discoloration is probably independent of wood origin and can be prevented by quick kiln drying without oxygen.     

ELECTROCHEMICAL IBTERACTIOS OF BEYPAZARI LIGNITE IS STROHG ACIDIC MED1A

Beypazari lignite was extracted with acetonltrile and acetonitrile/HClO₄ and electrochemical hydrogenation of the lignite in acetonltrile/LlC10₄ in the presence of HClO₄. was investigated. Controlled potential electrolysis experiments were carried out at -0.5 V vs a Ag/AgCl electrode. Infrared spectra of the products were measured and yields of extraction were determined. Extraction yields In acetonitrile and acetonitrile/HCIO₄ were 9 and 17.3 %, respectively. The yield of extractable material did not increased in the electrochemical environment. Acetonltrile extraction produced residual matter with less hydroxyl groups. Stirring the lignite in acetonitrile(HClO₄ for 7 hours oxidized both the extract and the residue. The residue seemed to contain less hydroxyl groups than that of the acetonltrile extraction residue and It has new carbonyl and etheric groups that were absent in the original lignite. It was found that the material extracted during electrochemical treatment by acetonitrile/HClO₄ was hydrogenated and the coal matrix remained intact. As the quantity of HClO₄ consumed in electrolysis was increased the amount of methyl groups in the extract also increased. Higher potentials are probably neccessary to hydrogenate the coal matrix by the electrochemlcally produced hydrogen atoms.     

Drawbacks in the use of the Biuret method for determination of the same protein in differently treated fish samples

There was a considerable difference in absorption (due to proteins) at 540 nm between fresh fish and frozen, thawed fish flesh using the Biuret method on the same raw material on the same day. This difference was increased after a day, giving lower results.     

Uranium immobilization by sulfate-reducing biofilms grown on hematite, dolomite, and calcite

Biofilms of sulfate-reducing bacteria Desulfovibrio desulfuricans G20 were used to reduce dissolved U(VI) and subsequently immobilize U(IV) in the presence of uranium-complexing carbonates. The biofilms were grown in three identically operated fixed bed reactors, filled with three types of minerals: one noncarbonate-bearing mineral (hematite) and two carbonate-bearing minerals (calcite and dolomite). The source of carbonates in the reactors filled with calcite and dolomite were the minerals, while in the reactor filled with hematite it was a 10 mM carbonate buffer, pH 7.2, which we added to the growth medium. Our five-month study demonstrated that the sulfate-reducing biofilms grown in all reactors were able to immobilize/reduce uranium efficiently, despite the presence of uranium-complexing carbonates.     

Immobilization of U(VI) from oxic groundwater by Hanford 300 Area sediments and effects of Columbia River water

Regions within the U.S. Department of Energy Hanford 300 Area (300 A) site experience periodic hydrologic influences from the nearby Columbia River as a result of changing river stage, which causes changes in groundwater elevation, flow direction and water chemistry. An important question is the extent to which the mixing of Columbia River water and groundwater impacts the speciation and mobility of uranium (U). In this study, we designed experiments to mimic interactions among U, oxic groundwater or Columbia River water, and 300 A sediments in the subsurface environment of Hanford 300 A. The goals were to investigate mechanisms of: 1) U immobilization in 300 A sediments under bulk oxic conditions and 2) U remobilization from U-immobilized 300 A sediments exposed to oxic Columbia River water. Initially, 300 A sediments in column reactors were fed with U(VI)-containing oxic 1) synthetic groundwater (SGW), 2) organic-amended SGW (OA-SGW), and 3) de-ionized (DI) water to investigate U immobilization processes. After that, the sediments were exposed to oxic Columbia River water for U remobilization studies. The results reveal that U was immobilized by 300 A sediments predominantly through reduction (80-85%) when the column reactor was fed with oxic OA-SGW. However, U was immobilized by 300 A sediments through adsorption (100%) when the column reactors were fed with oxic SGW or DI water. The reduced U in the 300 A sediments fed with OA-SGW was relatively resistant to remobilization by oxic Columbia River water. Oxic Columbia River water resulted in U remobilization (∼7%) through desorption, and most of the U that remained in the 300 A sediments fed with OA-SGW (∼93%) was in the form of uraninite nanoparticles. These results reveal that: 1) the reductive immobilization of U through OA-SGW stimulation of indigenous 300 A sediment microorganisms may be viable in the relatively oxic Hanford 300 A subsurface environments and 2) with the intrusion of Columbia River water, desorption may be the primary process resulting in U remobilization from OA-SGW-stimulated 300 A sediments at the subsurface of the Hanford 300 A site.     

Shape Memory Behavior of [111]-Oriented NiTi Single Crystals After Stress-Assisted Aging

The shape memory behavior of [111]-oriented Ni_(51)Ti_(49) (at.%) single crystals was investigated after stressassisted aging at 500 °C for 1.5 h under a compressive stress of-150 MPa.It was found that a single family of Ni_4Ti_3 precipitates with two crystallographically equivalent variants was formed after aging under compressive stress.Stressassisted aging resulted in tensile two-way shape memory effect strain of 1.56% under-5 MPa.Thermal cycling under-600 MPa resulted in a transformation strain of-2.15%,while the subsequent thermal cycling under-5 MPa resulted in a tensile two-way shape memory effect strain of 2.2%.