Short Bridges Research Articles

Economic and environmental life cycle assessment of a short-span aluminium composite bridge deck in Canada

The costs to maintain Québec's infrastructure—most of which was built in the 1960s and 1970s—are considerable, and major maintenance and reconstruction will be required in the coming years. In recent years, aluminum associations promote the increase of aluminum use in infrastructure and especially in bridge construction. This research aims to investigate the advantages of using aluminum deck bridges, which require less maintenance than traditional materials due to the natural resistance to atmospheric corrosion of aluminum, despite their higher investment costs that may limit their deployment. More specifically, the study compares for the first time the life cycle costs and environmental impacts of an aluminum-steel composite deck with a more traditional concrete-steel composite deck and provides a parametrized model allowing practitioners and designers to perform screening life cycle assessment and cost of short span bridge based on our data and results. Results show that the initial cost of aluminum deck is double that of concrete deck, but the overall cost is actually four times lower over the entire life cycle. The environmental results demonstrate the benefits of aluminum deck. Our main recommendation for future decision making in road infrastructure management is therefore to systematically expand the scope of the analysis integrating a full life cycle thinking also including the effects from traffic diversion.

Voltage controllable superconducting state in the multiterminal superconductor–normal-metal bridge

We study voltage controllable superconducting state in multi-terminal bridge composed of the dirty superconductor/pure normal metal (SN) bilayer and pure normal metal. In the proposed system small control current $I_{ctrl}$ flows via normal bridge, creates voltage drop $V$ and modifies distribution function of electrons in connected SN bilayer. In case of long normal bridge the voltage induced nonequilibrium effects could be interpreted in terms of increased local electron temperature. In this limit we experimentally find large sensitivity of critical curent $I_c$ of Cu/MoN/Pt-Cu bridge to $I_{ctrl}$ and relatively large current gain which originate from steep dependence of $I_c$ on temperature and large $I_c$ (comparable with theoretical depairing current of superconducting bridge). In the short normal bridge deviation from equilibrium cannot be described by simple increase of local temperature but we also theoretically find large sensitivity of $I_c$ to control current/voltage. In this limit we predict existence at finite $V$ of so called in-plane Fulde-Ferrell state with spontaneous currents in SN bilayer. We argue that its appearance is connected with voltage induced paramagnetic response in N layer.

Catalytic Enantioselective Rotation of Watermill‐Shaped Dinuclear Pd Complexes

AbstractThe catalytic enantioselective rotation of double‐paddled, watermill‐shaped palladium complexes is described in this report. The achiral syn‐ and chiral anti‐forms of binuclear trans‐bis(salicylaldiminato)palladium(II) complexes doubly linked with polymethylene bridges (1) were synthesized and subsequently characterized by spectroscopic and single crystal XRD analyses. The heptamethylene‐linked complex 1 b undergoes highly controllable rotation between the achiral syn and chiral anti‐forms at ambient temperature, while the hexamethylene‐linked analogue 1 a does not exhibit this rotational motion under the same conditions, due to its shorter bridges, and 1 c (with octamethylene linkers) undergoes uncontrollable rapid rotation even at lower temperatures. The kinetics of the dynamic rotation of syn‐1 b to the anti‐isomer in solution were examined on the basis of 1H NMR analyses. The data showed that the rotational rate can be greatly modified by varying the solvent or adding a carboxylic acid. The enantioselective rotation of syn‐1 b can be induced using a catalytic amount of (2R,3R)‐2,3‐bis(3,5‐dimethylbenzoyl)tartaric acid (2 a) to afford (R)‐anti‐1 b, with an initial enantiomeric excess of 63 % ee and an equilibrium value of 27 % ee. Curve fitting of data for the parallel reversible transformations of syn‐1 b to (R) and (S)‐anti‐1 b gave the forward and reverse first‐order rate constants k1, k−1 (for syn to (R)‐anti), k2 and k−2 (syn‐ to (S)‐anti), and verified that the enantioselective nature of the present catalytic enantioselective rotation is controlled kinetically during the initial stage (k1>k2) and thermodynamically in the equilibrium state (k1/k−1>k2/k−2). The specific changes induced in the transition states in response to the use of various solvents and adducts are discussed herein on the basis of the activation parameters for the rotation of syn‐1 b, as determined from plots of the kinetic data as functions of time.

A computed tomography cadaveric study of the radiological anatomy of the patella: the size of the patella correlates with bone bridge between tunnels and R angles are introduced for safe tunnel drilling during MPFL reconstruction

PurposeTo measure the safe range of angles during tunnel drilling and map ideal patella tunnel placement with the use of preoperative computed tomography (CT) scan and compare results after medial patellofemoral ligament (MPFL) reconstruction using a hardware-free patellar fixation technique with two semi-patellar tunnels between a) a free-hand technique, and b) its modification with the use of an anterior cruciate ligament (ACL) tibia aiming device.MethodsCT scan was performed on 30 fresh-frozen cadaveric knees a) prior to any intervention and b) after MPFL reconstruction. For MPFL reconstruction, specimens were randomly allocated to 1) Group A, which consisted of knees operated with free-hand, hardware-free patellar fixation technique with two semi-patellar tunnels and 2) Group B, which consisted of knees operated on with a technique modification with the ACL tibia device.Patellar measurementsL1 was the maximal patellar length. L2 was the minimum possible distance of placement for the upper tunnel from the proximal pole of the patella. The maximum bone bridge between tunnels was calculated as half of L1 minus the L2 distance (L1/2-L2). We also measured R1 and R2 angles at the proximal and distal tunnel that represent safe angles at the entry point during tunnel drilling (without breaching the anterior cortex or articular cartilage).ResultsPreoperatively, mean L1 was 3.45 cm (range 3.05–4.52). Mean L2 was 0.62 cm (range 0.49–0.89). The mean maximum possible bone bridge between tunnels (L1/2-L2) was 1.1 cm (range 0.77–1.58).R1 was 6.050 (range 4.78–7.44), R2 was 6.640 (range 4.57–9.03), and their difference reached statistical significance (p = 0.03). Postoperatively, in group A, in 4 out of 15 patellas, multiple attempts were made during tunnel drilling in order to avoid anterior cortex or cartilage breaching. In group B, all tunnels were correctly drilled with the first attempt. Bone bridge between tunnels was significantly shorter postoperatively (0.93 cm, p < 0.01).ConclusionSmall-size patellae correlate with short maximum bone bridge between tunnels, which makes anatomic, double-bundle, hardware-free patella fixation, with two semi-patellar tunnels MPFL reconstruction challenging. Furthermore, R angles create a narrow window to avoid intraoperative breaching, rendering the use of the ACL tibia device an extremely useful instrument.Level of evidenceII

Chemical studies of some fused heterocyclic compounds containing oxygen with anticipated biological interests: Thesis Abstract

Thesis AbstractBackground: Heterocyclic are known to have multiple applications in particular biomedical settings. Aim: The present study reports a convenient protocol for the design and synthesis of new heterocyclic compounds incorporating 1- hydroxy-naphthyl and new angular chromones bearing allylnaphthyl fragments. Materials and Methods: The versatile precursor 2-acetyl-4- allyl-1-hydroxy naphthalene was subjected to Claisen-Schmidt condensation but the precursor 6-allyl-3-formyl-4H-benzo[h]chromone was prepared via Vilsmeier–Haack reaction of 4-allyl-1- hydroxy-2-acetonaphthone. Results: Some new compounds are considered as promising leads with dual biological activity as antibacterial and antioxidant. The isoalloxazine ring of the cofactor FAD is essential to the recognition of the compound that has proper antioxidant activity. Benzocoumarin ring is essential for the recognition of the amino acid residues. Allyl chain improves the p stacking interaction while the n-propyl chain attenuates the overall interaction. Naphthyl ring needs to be substituted with a short bridge to avid the ring extended away from the pocket. The antimicrobial and antiquorum-sensing activities of the newly synthesized compounds showed that many compounds have good and promising activities in comparison with the reference drugs. Conclusion: Based on the computational prediction of pharmacokinetics, drug-likeness properties, biological activity, and molecular docking suggested that formyl chromone and tetracarbonyl may be potent antimicrobial drugs

Chemical Studies on Some Chromone Derivatives with Anticipated Pharmaceutical Applications: Thesis Abstract

The present study reports a convenient protocol for the design and synthesis of new heterocyclic compounds incorporating 1- hydroxy-naphthyl and new angular chromones bearing allylnaphthyl fragments. The versatile precursor 2-acetyl-4- allyl-1-hydroxy naphthalene was subjected to Claisen-Schmidt condensation but The precursor 6-allyl-3-formyl-4H-benzo[h]chromone was prepared via Vilsmeier–Haack reaction of 4-allyl-1- hydroxy-2-acetonaphthone.Some new compounds are considered as promising leads with dual biological activity as antibacterial and antioxidant. The isoalloxazine ring of the cofactor FAD is essential to the recognition of the compound that has proper antioxidant activity. Benzocoumarin ring is essential for the recognition of the amino acid residues. Allyl chain improves the p stacking interaction while the n-propyl chain attenuates the overall interaction. Naphthyl ring needs to be substituted with a short bridge to avid the ring extended away from the pocket.The antimicrobial and antiquorum-sensing activities of the newly synthesized compounds showed that many compounds have good and promising activities in comparison with the reference drugs. Computational prediction of pharmacokinetics, drug-likeness properties, biological activity, and molecular docking suggested that formyl chromone and tetracarbonyl may be potent antimicrobial drugs.

Experimental investigation of unbonded ordinary steel reinforced elastomeric bearings as an isolation system in bridges

Reduction of large tensile stresses and cost-efficiency has made unbonded isolators an attractive option as an isolation system. Following this idea and the results obtained by various researchers, it is shown that unbonded steel-reinforced elastomeric bearings (SREBs), which are used and designed for non-seismic actions, have inherently acceptable characteristics in tolerating large shear deformations for a cost-effective isolation system and can provide improved structural performance. However, this capacity is neglected in the design process. The current article presents an experimental program to analyze the mechanical properties of steel-reinforced natural rubber bearings without the upper and lower endplates when subjected to large shear displacements and to assess how they can be used and what are the limitations. The overall behavior of the bearing is explained and the affecting variables including the level of axial load, rate of loading, and contact conditions are discussed. A full-scale test setup using a pair of bearings sandwiched between three concrete platens is utilized which considers the interaction of compressive and cyclic shear loading. Even though it is costly and difficult, this setup provides a realistic approach for testing bearings while they are in contact with concrete on both sides. The test results reveal that under different vertical loading levels, all bearings exhibited stable hysteretic response. In presence of adequate axial load, the specimens were capable of tolerating shear strains more than 125% without slippage of the bearings. It was shown that albeit demonstrating low damping characteristics, these bearings provide adequate flexibility and shear displacement capacity which indicates they can be a proper choice for substitution as costly isolators in low to moderate seismic zones or for low-risk short span bridges in developing countries.

The Surface Properties of Solutions of Dicationic Imidazolium Surfactants with Short Bridge Fragments

The pendant drop shape and oscillating pendant drop methods have been employed to study the surface tension and the dilatational rheological surface characteristics at the solution–air interface for aqueous solutions of dicationic imidazolium surfactants with extremely short bridge fragments. A high surface activity has been revealed for these surfactants. High values of the dilatational viscoelasticity modulus have been found for the surfactant solutions. The modulus values increase with a decrease in the length of bridge fragments and an increase in the length of hydrocarbon radicals in surfactant molecules.

Field Determined Live Load Distribution Factors for Modular Press-Brake-Formed Tub Girders

This paper is focused on the field performance of a modular press-brake-formed tub girder (PBFTG) system in short span bridge applications. The scope of this project to conduct a live load field test on West Virginia State Project no. S322-37-3.29 00, a bridge utilizing PBFTGs located near Ranger, West Virginia. The modular PBFTG is a shallow trapezoidal box girder cold-formed using press-brakes from standard mill plate widths and thicknesses. A technical working group within the Steel Market Development Institute’s Short Span Steel Bridge Alliance, led by the current authors, was charged with the development of this concept. Research of PBFTGs has included analyzing the flexural bending capacity using experimental testing and analytical methods. This paper presents the experimental testing procedures and performance of a composite PBFTG bridge.

Theoretical study on water adsorption and dissociation on the nickel surfaces.

Using density functional theory methods, H2O dissociation was investigated on the Ni(111), Ni(100), and Ni(110) surfaces. H and O atom as well as OH species adsorb stably at the high coordination sites. While on the Ni(110) surface, the OH species prefers at the twofold short bridge site because the adsorption on the fourfold hollow site is less feasible due to the increased distances between the nickel atoms. The amount of charge transfer is related to the adsorption stability. The more charge transfer, the more stable the adsorption. The charge transfer decreases in the order of O > OH > H. H2O molecule adsorbs at the top site in a configuration parallel to the surface. The final products are different for H2O dissociation due to the different mechanisms. On the Ni(111) surface, the final product is the O atom. On the Ni(100) and Ni(110) surfaces, the most abundant species are OH and H, but the reaction mechanisms were different. It is not necessary to linear BEP relationship for a given reaction on different surfaces. These results could provide fundamental insights into water behaviors and a favorable theoretical basis for further understanding and research on the interaction between water and metal surfaces.

Pushing the limits in photosensitizer-catalyst interaction via a short cyanide bridge for water oxidation

The realization of high-performance, precious-metal-free, stable, and robust photoanodes for water oxidation is one of the bottlenecks for dye-sensitized water splitting. Herein, we integrate an organic photosensitizer, which absorbs visible light above 500 nm, with a Prussian blue (PB) network to sensitize a visible-light-absorbing semiconductor, WO3. Through comprehensive steady-state and ultrafast transient absorption studies, we show that the coupling of a photosensitizer to a catalyst through a short cyanide bridging group in a PB structure generates appropriate energy levels for an efficient charge transfer from the photosensitizer to the visible-light-absorbing semiconductor. The photoanode retains its structural integrity and high photoelectrochemical activity for at least 2 h of solar irradiation under mildly acidic conditions (pH 3), which reaches around 1.30 mA/cm2 at 1.23 VRHE. This work provides a simple recipe with a toolbox that can be extended to a variety of organic photosensitizers and semiconductors.

Damage reduction countermeasures for short span bridges focusing on restorability of structural joints

Lying on one of the world's most active seismic faults, Japan faces the continuous threat of natural disasters. The earthquake that struck east Japan on 11 March 2011, and the devastating tsunami, raised many very serious questions about this country's land and its disaster prevention and disaster reduction strategies for resilience. Disaster-related losses cause short- as well as long-term adverse effects on economy, society, health, culture and the environment. In Japan, the events of 11 March 2011 highlighted the need for the related government agencies, municipalities, research organisations and universities to work together in formulating and implementing a holistic and comprehensive policy approach for damage reduction countermeasures. In this paper, damage reduction countermeasures for short span bridges are presented focusing on the restorability of structural joints, with a view to earthquakes, tsunamis, floods, and deterioration.

Unravelling the role of charge transfer state during ultrafast intersystem crossing in compact organic chromophores.

When organic electron donor (D) and acceptor (A) chromophores are linked together, an electron transfer (ET) state can take place. When a short bridge such as one Sigma bond is used to link the donor and the acceptor, complete charge separation is difficult to access and one usually observes an intramolecular charge transfer (CT) state instead. Due to the inevitable coupling between the donor and the acceptor in compact organic chromophores, the most common decay pathway for the CT state is charge recombination, which may lead to a distinct longer wavelength fluorescence emission or non-radiative dissipation of the excited state energy. However, recent studies have shown that unique excited state dynamics can be observed when the CT state is involved during both forward and backward intersystem crossing (ISC) from singlet excited states to triplet excited states in organic chromophores. Analysis of the mechanism for ISC involving the CT state has received much attention over the last decade. In this perspective, we present a collection of molecular design rationales, spectroscopy and theoretical investigations that provide insights into the mechanism of the ISC involving the CT state in compact organic chromophores. We hope that this perspective will prove beneficial for researchers to design novel compact organic chromophores with a predictable ISC property for future biochemical and optoelectronic applications.

Damage reduction countermeasures for short span bridges focusing on restorability of structural joints

Damage reduction countermeasures for short span bridges focusing on restorability of structural joints

Effect of Coverage on Adsorptions of CO on Ni(110) Surface

The adsorptions of CO on Ni(110) surface at different coverages have been investigated by first-principle calculations. The results show that CO will be bonded at short bridge site preferentially. And CO preferentially absorbs upright at short bridge sites and top sites at 1/6 monolayer coverage. With increasing coverage to 0.5 ML, the enhanced steric repulsion leads to the slope of CO. For 1/6 and 1/2 monolayer coverage, CO is mainly bonded at short bridge site and atop site simultaneously at a certain ratio. When CO coverage is 1 monolayer, CO absorbs at short bridge site and forms p2mg configuration. As the coverage of CO is increased to finally form the p2mg structure, there is a continuous frequency shift up to the value 1962.27 cm-1. The vibration frequencies we calculated are consistent with relative experimental results. DOS of CO molecules and Ni atoms are discussed too.

The nature of the hydrogen interaction on the unreconstructed platinum (110) surface: ab-initio study

The theoretical description of the interaction of the hydrogen atoms on the unreconstructed platinum surface Pt(110) was studied within the density functional theory (DFT) calculation. The most stable sites of the adsorbed hydrogen atom on the surface were confirmed: the H atom on the short bridge site (B), and the H atom on the top site (T). By performing the Monte Carlo (MC) simulation for the obtained gas model parameterized by the DFT method, the abundance of B over T was presented. The 5% underestimation of the hydrogen interaction energy in this work compared with the Cyclic Voltammetry experiment was shown. It can be caused by the omission of the hydration effect in the simulation calculation.

First stable (Z)-configuration of cyanostilbene derivative: An effective “turn-on“ fluorescent sensor for lysine in aqueous media

Due to the rapid E/Z isomerization of cyanostilbene under light or heating, the stable (Z)-configuration of cyanostilbene was hard to be obtained although many (E)-cyanostilbene derivatives had been reported as excellent fluorescence sensor. In this work, the first stable (Z)-configuration of cyanostilbene derivative (Z)-CS bridged by crown-ether chain was designed and synthesized under the irradiation of UV365 and heating. The stable (Z)-configuration was attributed to the short bridging crown-ether chain which restricted the E/Z isomerization of cyanostilbene. (Z)-CS exhibited the weak AIE effect in H2O/DMSO system, but showed the strong “turn-on” fluorescence enhancement after adding lysine. The detection limit of (Z)-CS for lysine attained 1.34 × 10−7 M. The selective sensing behavior for lysine was stable in pH = 6–9 and was little interfered by other species. The 1:1 sensing mechanism was proposed by the investigation of Job’s plot, 1H NMR and MS binding spectra. The sensing ability of (Z)-CS was successfully applied for analyzing lysine in urine samples of human body. (Z)-CS also displayed the good bioimaging performance with enhanced blue-purple fluorescence after detecting lysine. The work not only presented an effective fluorescence sensor for lysine in aqueous media, but also confirmed firstly the excellent application prospect of stable (Z)-configuration of cyanostilbene as fluorescence probe in complicated and living environment.

Icosahedral Cobalt Bis(dicarbollide) Ions with Bridge Linker and Their Electrochemistry in Aqueous Media

Boron cluster compounds (BCC) proved recently promising properties for use in drug design and molecular probes. Their applications in medicine are inherently connected with use of water-based environments. Up to now, the BCC were predominantly characterized in non-aqueous milieus. Therefore, we decided to perform electrochemical research of BCC in water-based electrolytes. We have focused on several boron clusters with structures that follow our previous study on icosahedral cobalt bis(dicarbollide) ions with a central coordination Co(III) atom in phosphate buffers, where we have found the best response for bridge type of exo-skeletal substituent. Therefore, in present study, we decided to focus on the promising structures, in which two 11 vertexes C2B9 dicarbollide ligands are interconnected via short bridge. Such structures may contain side chains usable for bioconjugation experiments.For our electrochemical experiments, we have used phosphate buffers of different pHs (2-10) and polished glassy carbon electrode. As the bridge structure served these exo-skeletal substituents: sulfur, amino group, tolylene, chlorpehenylene, phenylene, xylylene, byphenylene, phosphoric groups.The effect of various exo-skeletally substituted cobaltacarboranes (differing in type and length of the side chain) on the electrochemical response was studied. The results show that all parameters, the peak shape, the potential position and the peak current density height are significantly altered by the endo- and exo- skeletal substituents. Within the range of studied substitution, we were able to detect the signals in a broad potential range from E = -1.38 V to E = 1.73 V. From this follows clear possibilities to tune the position of two potential types in the electrochemical window that alternatively correspond either to the oxidation of the core structure of boron polyhedra or the central Co(III). The results also show that the electrochemical methods represent another tool for fast tracking the aggregation phenomena connected with non-classical amphiphilic behavior of boron clusters in aqueous solutions

Phonon investigation on the interaction of hydrogen on the missing row Pt (110)-(1x2) surface

The phonon calculations of hydrogen when adsorbed on the missing row Pt(110)-(1x2) surfaceusing the Ultrahigh Vacuum (UHV) model were studied. The calculations were based on a combinationof Density Functional Theory (DFT) and the approximation of hydrogen vibrations on thesurface. The harmonic vibration of H on the Pt surface was used for the calculation in this study. Atthe hydrogen coverage of 1ML for the model surface (when H completely covering the Pt surface),the interaction formed at the edge of the first layer (short bridge - R) was the most stable. The lessstable positions were recorded as the bridge position between two atoms on a horizontal row inthe second layer (trough - T), the top position of the second surface layer - fcc (F), the bridge positionof the second surface layer - hcp (F'), and the least stable position was the top position of thefirst layer (T'). When accounting the quantum calculation for the model, the adsorption energy ofhydrogen at the short bridge position increased by 90 meV, and the stable adsorption order of hydrogenchanged with the most stable positions ware R, T, T', F', F respectively. This demonstratesdthe significant influence of quantum effects on the adsorption model.

S1306 Outcomes of Enteroscopy-Assisted Direct Percutaneous Endoscopic Jejunostomy (DPEJ) Tube Placement – A Single Center Experience

INTRODUCTION: To study and report the clinical experience of direct percutaneous endoscopic jejunostomy (DPEJ) in a single tertiary care center. METHODS: Forty-eight (48) patients underwent DPEJ tube placement over the last 6 years (9/2013-10/2019) at a single tertiary care center. The main outcome measurements were a technical success in native and altered anatomy, and short- and long-term follow up. DPEJ was attempted in 48 patients – 63% females, age 52.5 ± 15.4 years, BMI 21.1 ± 6.8 kg/m2. Indications included gastroparesis (n = 12), Parkinson’s disease (n = 4), chronic pancreatitis (n = 7), chronic malnutrition with multiple abdominal surgeries (n = 12), intractable nausea and vomiting (n = 8) and others (n = 5). RESULTS: DPEJ was successful in 42/48 (87.5%) patients. It was placed using double-balloon enteroscopy (DBE) in 34 patients, single balloon enteroscopy in 1 patient, and push enteroscopy in 7 patients based on the endoscopist’s discretion and experience. Technical failures were due to lack of trans-illumination (n = 4), ventral hernia (n = 1), and previous adhesions hampering the advancement of the DBE (n = 1). All these patients underwent DBE to attempt the placement of DPEJ. Thirty-day complications were very few. There was no difference in the complications between altered and native anatomy (29% vs 20%, P = 0.32). There was no difference in the other outcomes (failure rates, tube removed, duration of PEJ tube) as well between the two groups. DPEJ was a short term bridge for 14 patients with a mean time to removal being 8 ± 7 months. Only one patient requested the DPEJ to be removed after 4 months due to discomfort and did not require any other supplemental nutrition. Patients who had DPEJ removed had a significant improvement in their serum albumin as compared to the patients who did not have their removed DPEJ removed (1 ± 0.6 g/dL vs 0.4 ± 0.5 g/dL, P = 0.05). 61% of all patients did not have the DPEJ removed. The mean duration of follow up in those patients was 23 ± 17 months with the first tube lasting for a mean duration of 12 ± 8 months and requiring exchanges of DPEJ. CONCLUSION: DPEJ is associated with a high technical success rate that is not influenced by altered anatomy and offers nutritional support with a low perioperative complication rate. It can often be used as a short term bridging therapy in some patients.Table 1.: Demographics of the 48 patients who underwent enteroscopy-assisted direct percutaneous endoscopic jejunostomy procedure