Effects Of The Flash Welding Process On Mechanical And Microstructural Properties Of Structural Steel Joints Assessed Using Dest

ASTM A529 carbon¿manganese steel angle specimens were joined by flash butt welding and the effects of varying process parameter settings on the resulting welds were investigated. The weld metal and heat affected zones were examined and tested using tensile testing, ultrasonic scanning, Rockwell hardness testing, optical microscopy, and scanning electron microscopy with energy dispersive spectroscopy in order to quantify the effect of process variables on weld quality. Statistical analysis of experimental tensile and ultrasonic scanning data highlighted the sensitivity of weld strength and the presence of weld zone inclusions and interfacial defects to the process factors of upset current, flashing time duration, and upset dimension. Subsequent microstructural analysis revealed various phases within the weld and heat affected zone, including acicular ferrite, Widmanstätten or side-plate ferrite, and grain boundary ferrite. Inspection of the fracture surfaces of multiple tensile specimens, with scanning electron microscopy, displayed evidence of brittle cleavage fracture within the weld zone for certain factor combinations. Test results also indicated that hardness was increased in the weld zone for all specimens, which can be attributed to the extensive deformation of the upset operation. The significance of weld process factor levels on microstructure, fracture characteristics, and weld zone strength was analyzed. The relationships between significant flash welding process variables and weld quality metrics as applied to ASTM A529-Grade 50 steel angle were formalized in empirical process models.

Mental Health and Aging at the 2005 White House Conference on Aging: Two Steps Forward, One Step Back

Success! At the 2005 White House Conference on Aging, three-quarters of the 1,200 national delegates voted to improve “recognition, assessment, and treatment of mental illness and depression among older Americans.” This resulted in mental health being ranked as #8 of the final 50 WHCoA policy resolutions resulting from the conference. Joining this resolution in the “top ten” were two resolutions intimately tied to hopes for addressing the mental health needs of older adults—at #6 “Support Geriatric Education and Training for Health Care Professionals, Paraprofessionals, Health Profession Students and Direct Care Workers,” and #9 “Attain Adequate Numbers of Healthcare Personnel in All Professions Who are Skilled, Culturally Competent, and Specialized in Geriatrics.”

Polymerization of Styrene and Cyclization to Macrocyclic Polystyrene in a One-Pot, Two-Step Sequence

Dibrominated polystyrene (BrPStBr) was produced by atom transfer radical polymerization (ATRP) at 80 degrees C, using the bifunctional initiator benzal bromide to afford the telechelic precursor. The ATRP reaction was stopped around 40% monomer conversion and directly converted into an radical trap-assisted atom transfer radical coupling (RTA-ATRC) reaction by lowering the temperature to 50 degrees C, and adding the radical trap 2-methyl-2-nitrosopropane (MNP) along with additional catalyst, reducing agent, and ligand to match ATRC-type reaction conditions. In an attempt to induce intramolecular coupling, rather than solely intermolecular coupling and elongation, the total reaction volume was increased by the addition of varying amounts of THF. Cyclization, along with intermolecular coupling and elongation, occurred in all cases, with the extent of ring closure a function of the total reaction volume. The cyclic portion of the coupled product was found to have a (G) value around 0.8 by GPC analysis, consistent with the reduction in hydrodynamic volume of a cyclic polymer compared to its linear analog. Analysis of the sequence by H-1 NMR confirmed that propagation was suppressed nearly completely during the RTA-ATRC phase, with percent monomer conversion remaining constant after the ATRP phase. (C) 2013 Elsevier Ltd. All rights reserved.

First-day step-down to oral outpatient treatment versus continued standard treatment in children with cancer and low-risk fever in neutropenia. A randomized controlled trial within the multicenter SPOG 2003 FN study

The standard treatment of fever in chemotherapy-induced neutropenia (FN) includes emergency hospitalization and empirical intravenous antimicrobial therapy. This study determined if first-day step-down to oral outpatient treatment is not inferior to continued standard regarding safety and efficacy in children with low-risk FN.

Ethnosciences - A step towards the integration of scientific and non-scientific forms of knowledge in the management of natural resources for the future

Integration of indigenous knowledge and ethnoscientific approaches into contemporary frameworks for conservation and sustainable management of natural resources will become increasingly important in policies on an international and national level. We set the scene on how this can be done by exploring the key conditions and dimensions of a dialogue between ‘ontologies’ and the roles, which ethnosciences could play in this process. First, the roles which ethnosciences in the context of sustainable development were analysed, placing emphasis on the implications arising when western sciences aspire to relate to indigenous forms of knowledge. Secondly, the contributions of ethnosciences to such an ‘inter-ontological dialogue’ were explored, based on an ethnoecological study of the encounter of sciences and indigenous knowledge in the Andes of Bolivia, and reviewed experiences from mangrove systems in Kenya, India and Sri Lanka, and from case-studies in other ecosystems world-wide.

ANKLE IMPEDANCE AND ANKLE ANGLES DURING STEP TURN AND STRAIGHT WALK: IMPLICATIONS FOR THE DESIGN OF A STEERABLE ANKLE-FOOT PROSTHETIC ROBOT

During locomotion, turning is a common and recurring event which is largely neglected in the current state-of-the-art ankle-foot prostheses, forcing amputees to use different steering mechanisms for turning, compared to non-amputees. A better understanding of the complexities surrounding lower limb prostheses will lead to increased health and well-being of amputees. The aim of this research is to develop a steerable ankle-foot prosthesis that mimics the human ankle mechanical properties. Experiments were developed to estimate the mechanical impedance of the ankle and the ankles angles during straight walk and step turn. Next, this information was used in the design of a prototype, powered steerable ankle-foot prosthesis with two controllable degrees of freedom. One of the possible approaches in design of the prosthetic robots is to use the human joints’ parameters, especially their impedance. A series of experiments were conducted to estimate the stochastic mechanical impedance of the human ankle when muscles were fully relaxed and co-contracting antagonistically. A rehabilitation robot for the ankle, Anklebot, was employed to provide torque perturbations to the ankle. The experiments were performed in two different configurations, one with relaxed muscles, and one with 10% of maximum voluntary contraction (MVC). Surface electromyography (sEMG) was used to monitor muscle activation levels and these sEMG signals were displayed to subjects who attempted to maintain them constant. Time histories of ankle torques and angles in the lateral/medial (LM) directions, inversion-eversion (IE), and dorsiflexionplantarflexion (DP) were recorded. Linear time-invariant transfer functions between the measured torques and angles were estimated providing an estimate of ankle mechanical impedance. High coherence was observed over a frequency range up to 30 Hz. The main effect of muscle activation was to increase the magnitude of ankle mechanical impedance in all degrees of freedom of the ankle. Another experiment compared the three-dimensional angles of the ankle during step turn and straight walking. These angles were measured to be used for developing the control strategy of the ankle-foot prosthesis. An infrared camera system was used to track the trajectories and angles of the foot and leg. The combined phases of heel strike and loading response, mid stance, and terminal stance and pre-swing were determined and used to measure the average angles at each combined phase. The Range of motion (ROM) in IE increased during turning while ML rotation decreased and DP changed the least. During the turning step, ankle displacement in DP started with similar angles to straight walk and progressively showed less plantarflexion. In IE, the ankle showed increased inversion leaning the body toward the inside of the turn. ML rotation initiated with an increased medial rotation during the step turn relative to the straight walk transitioning to increased lateral rotation at the toe off. A prototype ankle-foot prosthesis capable of controlling both DP and IE using a cable driven mechanism was developed and assessed as part of a feasibility study. The design is capable of reproducing the angles required for straight walk and step turn; generates 712N of lifting force in plantarflexion, and shows passive stiffness comparable to a nonload bearing ankle impedance. To evaluate the performance of the ankle-foot prosthesis, a circular treadmill was developed to mimic human gait during steering. Preliminary results show that the device can appropriately simulate human gait with loading and unloading the ankle joint during the gait in circular paths.

Nanofabrication of Surface-Enhanced Raman Scattering Device by an Integrated Block-Copolymer and Nanoimprint Lithography Method

The integration of block-copolymers and nanoimprint lithography presents a novel and cost-effective approach to achieving nanoscale patterning capabilities. The authors demonstrate the fabrication of a surface-enhanced Raman scattering device using templates created by the block-copolymers nanoimprint lithography integrated method.

Tax-Optimal Step-Up and Imperfect Loss Offset

In the field of mergers and acquisitions, German and international tax law allow for several opportunities to step up a firm's assets, i.e., to revaluate the assets at fair market values. When a step-up is performed the taxpayer recognizes a taxable gain, but also obtains tax benefits in the form of higher future depreciation allowances associated with stepping up the tax base of the assets. This tax-planning problem is well known in taxation literature and can also be applied to firm valuation in the presence of taxation. However, the known models usually assume a perfect loss offset. If this assumption is abandoned, the depreciation allowances may lose value as they become tax effective at a later point in time, or even never if there are not enough cash flows to be offset against. This aspect is especiallyrelevant if future cash flows are assumed to be uncertain. This paper shows that a step-up may be disadvantageous or a firm overvalued if these aspects are not integrated into the basic calculus. Compared to the standard approach, assets should be stepped up only in a few cases and - under specific conditions - at a later point in time. Firm values may be considerably lower under imperfect loss offset.

Hemozoin formation in malaria: a two-step process involving histidine-rich proteins and lipids

Major blood stage antimalarial drugs like chloroquine and artemisinin target the heme detoxification process of the malaria parasite. Hemozoin formation reactions in vitro using the Plasmodium falciparum histidine-rich protein-2 (Pfhrp-2), lipids, and auto-catalysis are slow and could not explain the speed of detoxification needed for parasite survival. Here, we show that malarial hemozoin formation is a coordinated two component process involving both lipids and histidine-rich proteins. Hemozoin formation efficiency in vitro is 1-2% with Pfhrp-2 and 0.25-0.5% with lipids. We added lipids after 9h in a 12h Pfhrp-2 mediated reaction that resulted in sixfold increase in hemozoin formation. However, a lipid mediated reaction in which Pfhrp-2 was added after 9h produced only twofold increase in hemozoin production compared to the reaction with Pfhrp-2 alone. Synthetic peptides corresponding to the Pfhrp-2 heme binding sequences, based on repeats of AHHAAD, neither alone nor in combination with lipids were able to generate hemozoin in vitro. These results indicate that hemozoin formation in malaria parasite involves both the lipids and the scaffolding proteins. Histidine-rich proteins might facilitate hemozoin formation by binding with a large number of heme molecules, and facilitating the dimer formation involving iron-carboxylate bond between two heme molecules, and lipids may then subsequently assist the mechanism of long chain formation, held together by hydrogen bonds or through extensive networking of hydrogen bonds.

Reconstruction of a flash flood with large wood transport and its influence on hazard patterns in an ungauged mountain basin

The reconstruction of past flash floods in ungauged basins leads to a high level of uncertainty, which increases if other processes are involved such as the transport of large wood material. An important flash flood occurred in 1997 in Venero Claro (Central Spain), causing significant economic losses. The wood material clogged bridge sections, raising the water level upstream. The aim of this study was to reconstruct this event, analysing the influence of woody debris transport on the flood hazard pattern. Because the reach in question was affected by backwater effects due to bridge clogging, using only high water mark or palaeostage indicators may overestimate discharges, and so other methods are required to estimate peak flows. Therefore, the peak discharge was estimated (123 ± 18 m3 s–1) using indirect methods, but one-dimensional hydraulic simulation was also used to validate these indirect estimates through an iterative process (127 ± 33 m3 s–1) and reconstruct the bridge obstruction to obtain the blockage ratio during the 1997 event (~48%) and the bridge clogging curves. Rainfall–Runoff modelling with stochastic simulation of different rainfall field configurations also helped to confirm that a peak discharge greater than 150 m3 s–1 is very unlikely to occur and that the estimated discharge range is consistent with the estimated rainfall amount (233 ± 27 mm). It was observed that the backwater effect due to the obstruction (water level ~7 m) made the 1997 flood (~35-year return period) equivalent to the 50-year flood. This allowed the equivalent return period to be defined as the recurrence interval of an event of specified magnitude, which, where large woody debris is present, is equivalent in water depth and extent of flooded area to a more extreme event of greater magnitude. These results highlight the need to include obstruction phenomena in flood hazard analysis.