Adequate Lifetime Research Articles

Modified carbon paste electrodes for Cu(II) determination

A new Cu2+ carbon paste electrode (CPE) using 2,2′-(1E,1′E)-1,1′-(2,2′-azanediylbis (ethane-2,1-diyl)bis(azan-1-yl-1-ylidene))bis(ethan-1-yl-1-ylidene)diphenol (ADEZEDP) has been prepared. The influence of variables including sodium tetraphenylborate (NaTPB), ionophore, and amount of multiwalled carbon nanotubes (MWCNT), CdO nanowires, CdS nanoparticles and palladium nanoparticles loaded on ADEZEDP and Nujol on the electrodes response were studied and optimized. At optimum values of all variables, for each nanomaterial the electrode response was linear in concentration range of 1.0×10−8 to 1.0×10−1molL−1 for ADEZEDP with Nernstian slope. The good performance of electrode viz. Wide applicable pH range (2.0–5.0), fast response time (≈6s), and adequate life time (3months) indicate the utility of the proposed electrodes for evaluation of Cu2+ ion content in various situations. Finally, these electrodes have been successfully applied for the determination of Cu2+ ions content in various real samples. The selectivity of proposed electrode was evaluated by separation solution method and fixed interference method.

Novel multi walled carbon nanotubes/β-cyclodextrin based carbon paste electrode for flow injection potentiometric determination of piroxicam

A novel carbon paste electrode based on functionlized multi-walled carbon nanotubes/β-cyclodextrin composite (FMWCNTs/β-CD-CPE) is described for potentiometric determination of piroxicam (PXM). Improved sensitivity and selectivity was achieved by application of CDs as molecular host–guest recognition elements and MWCNTs. The electrochemical performance of carbon paste electrodes incroporated with FMWCNTs/β-CD composite was compared to those incroporated with MWCNTs and free CDs. Matrices compositions of each electrode are optimized on the basis of nature and content of the modifier, ionic sites and selected plasticizer. CPEs containing FMWCNTs/β-CD composite, hyamine (Hy) and 2-fluorophenyl 2-nitrophenyl ether (f-NPE) as electrode plasticizer, work satisfactory in the concentration range from 10−6 to 10−2molL−1 with Nernstain compliance (58.7±0.9mVdecade−1 activity) with fast response time of about 2s and exhibit adequate operational lifetime (16 weeks). The developed electrodes have been applied for the potentiometric determination of PXM in pharmaceutical formulation under batch and flow injection analysis (FIA). FIA allows the analysis of 120samplesh−1 with the advantage of simplicity, accuracy and automation feasibility.

Integration of batteries with ultracapacitors for a fuel cell hybrid transit bus

Battery electric vehicles and hybrid electric vehicles require electric energy storage systems that exhibit high energy and power density, as well as good cycle life. Batteries possess good energy density, whereas ultracapacitors possess high power density and cycle life. The complementary features of batteries and ultracapacitors can be advantageously combined to create an integrated system that exhibits high performance with low weight and adequate battery lifetime, at an affordable cost. This paper presents simulation studies on the benefits of adding ultracapacitors to a fuel cell battery hybrid transit bus operating on two standardized driving schedules (Manhattan Bus Cycle and UDDS). Simulations were conducted using our LFM powertrain simulator which was developed in MATLAB/SIMULINK. The energy storage systems considered here include battery only, as well as various combinations of batteries and ultracapacitors. Simulation results show that the addition of ultracapacitors greatly improves performance parameters such as battery C-rates, energy throughput, and energy storage heat generation at comparable cost and weight.

Novel PVC-membrane electrode for flow injection potentiometric determination of Biperiden in pharmaceutical preparations

The construction and performance characteristics of Biperiden (BP) polyvinyl chloride (PVC) electrodes are described. Different methods for electrode fabrication are tested including; incorporation of BP-ion pairs (BP-IPs), incorporation of ion pairing agents, or soaking the plain electrode in BP-ion pairs suspension solution. Electrode matrices were optimized referring to the effect of modifier content and nature, plasticizer and the method of modification. The proposed electrodes work satisfactorily in the BP concentration range from 10−5 to 10−2molL−1, with fast response time (7s) and adequate operational lifetime (28 days). The electrode potential is pH independent within the range 2.0–7.0, with good selectivity towards BP in presence of various interfering species. The developed electrodes have been applied for potentiometric determination of BP in pharmaceutical formulation under batch and flow injection analysis (FIA) conditions. FIA offers the advantages of accuracy and automation feasibility with high sampling frequency. The dissolution profile for Akineton tablets (2mg BP/tablet) was studied using the proposed electrode in comparison with the official methods.

Gd3Ga5O12:Cr—a phosphor for two-dimensional thermometry in internal combustion engines

The lifetime of thermographic phosphors needs to be short enough to resolve the temperature time scales and long enough to be properly resolved by the respective detector. Up until now, there has not been a thermographic phosphor that exhibits an adequate temperature lifetime characteristic for two-dimensional thermometry inside internal combustion engines using high speed cameras. Hence, this study suggests the material Gd3Ga5O12:Cr for this purpose. The emission spectra and the temperature lifetime characteristics were determined and the lifetime is shown to be independent of the composition and the absolute pressure of the surrounding gas phase.

Recent developments in the preparation, characterization and applications of glass- and glass–ceramic-to-metal seals and coatings

There has, in recent years, been a major revival of interest in glass- and glass–ceramic-to-metal seals and coatings for new applications. Experience dictates that many factors need to be taken into consideration in the successful design and manufacture of high-quality seals, particularly if an adequate component lifetime is to be achieved. For example, during their preparation, undesirable reactions may occur between diffusing metal species and glass constituents, and these can lead to the formation of highly localized internal stresses, which can initiate failure of a seal either during manufacture or, more seriously, whilst in service due to the influence of static fatigue. In the case of high-temperature systems, reactions under hostile operating conditions also need to be taken into consideration. In this review, the factors learnt from past experience that influence the formation and lifetime behaviour of glass and glass–ceramic/metal systems are briefly introduced, and their relevance to the newer applications including solid oxide fuel cell sealants and coatings on titanium for biomedical applications is discussed.

A técnica de dopagem no tratamento da zona de interface: ligações entre concreto novo e velho

Para que as estruturas de concreto alcancem uma vida útil adequada é necessário avaliar a durabilidade e considerar a manutenção das mesmas. Isso tem estimulado o desenvolvimento de tecnologias destinadas a solucionar a problemática de peças deterioradas ou danificadas. Este trabalho analisa o comportamento da zona de interface entre concreto novo e velho após a escarificação do concreto velho (tratamento físico) e o emprego da técnica de dopagem (tratamento químico). A técnica de dopagem consiste na impregnação de pó por via seca ou pasta de alto desempenho, seguida do lançamento de concreto novo, ou no lançamento direto de um concreto novo com características de alto desempenho. O desempenho dessa ligação foi avaliado por meio de ensaios de tração na flexão, até a ruptura, em corpos de prova prismáticos de concreto simples (fck = 20 MPa) e em seguida remoldados. A partir dos resultados, verificou-se que a ruptura dos corpos de prova recuperados ocorreu fora da região de interface e que as resistências à flexão desse concreto foram mantidas tais quais as originais, demonstrando a eficácia do procedimento na ligação entre concreto novo e velho.

Radiation Transport Analyses for Design Optimisation of the ITER Core LIDAR Diagnostic

Systematic analysis of the radiation fields throughout the ITER core LIDAR diagnostic system were performed to support the design optimisation and assessment process, aiming at achieving the required performance in terms of reliability, occupational safety and interface with neighboring systems. Neutron, photon, nuclear heat and material activation responses were estimated for a variety of configurations, and improved using a combination of analytical “rules of thumb” and numerical computations with the ATTILA™ and FISPACT codes. The neutron flux at the backplate of the port plug was significantly reduced (to ∼2x107 n/cm2-s) by fine-tuning the reference geometry of the laser labyrinth, and guidelines were provided for quick estimation of the effect of future design changes. The current design has adequate lifetime of essential optical components, in particular absorption in collection windows below ∼1%, and reduced dose to workers during maintenance according to the ALARA principle.

Nitrate-Selective Electrodes Based on the Trinuclear Chromium(III) Pivalates

The paper describes the analytical potentialities of the trinuclear chromium(III) complexes as potentiometric ionophores for the construction of electrodes sensitive to the presence of nitrate anion. The electroactive material containing 4,4’-bipyridil was synthesized in situ. The membrane was prepared using dioctylphthalate as a solvent mediator and poly (vinyl chloride) as a polymeric matrix. The electrodes presented a slope of 56 mV/decade, a low limit of detection (3,2.10-6 mol/l), an adequate lifetime (4 months), and suitable selectivity characteristics when compared with other nitrate electrodes. The good parameters of this electrode made possible its application to the determination of nitrate in different types of fertilizers.

Laser Fusion Chamber Design

A laser fusion chamber must absorb the energy emitted by the target in such a way that the plant can achieve a commercially viable power conversion efficiency. This must be accomplished with a design that can reliably withstand on the order of a billion shots. For a dry chamber wall, the key lifetime issues are thermo-mechanical effects resulting from the rapid heating, ion effects, such as blistering and sputtering, and radiation effects. These issues define the chamber size by providing flux limits for the various threats. In cases where a dry, unprotected wall cannot provide an adequate lifetime, measures must be taken to reduce the threat to the wall. Previously proposed approaches include filling the chamber with sufficient gas to stop the majority of the ions before they reach the wall or redirection of the ions by a cusp field. Other design trade-offs that must be addressed include the need to reduce heating of the target during injection and the need for adequate clearing of the chamber between shots. In this paper we provide a review of the chamber design approaches required for commercially viable laser fusion power plants, the issues driving those designs, and some system-level analyses that provide insight into the implications of these design issues for the overall economics of a commercial plant.

The association between non-melanoma skin cancer and osteoporotic fractures—a population-based record linkage study

We studied the association between osteoporotic fractures and prior non-melanoma skin cancer (NMSC, a biomarker for cumulative sun exposure). The risk of prior NMSC in our fracture cohort was significantly reduced (standardised incidence ratio 0.69, 95% CI 0.61, 0.78). Adequate lifetime sun exposure may be necessary to protect against osteoporotic fractures in later life. The relationship between cumulative sun exposure and osteoporotic fractures is uncertain. We aimed to study the association between non-melanoma skin cancer (NMSC), a marker of cumulative sun exposure, and osteoporotic fractures in an older cohort. A retrospective cohort study in southern Tasmania in people aged at least 50 years with incident radiographic fracture (n = 2,283) was carried out. By record linkage to the Tasmanian Cancer Registry the cohort was followed backwards through time until the occurrence of NMSC or end-of follow-up. Relative risk was estimated by the standardised incidence ratio (SIR) using sex-, age- and calendar year-specific cancer incidence rates in southern Tasmania as reference. The incidence of prior NMSC in the fracture cohort was 31% lower than for the general population (SIR 0.69, 95% CI 0.61, 0.78). This effect was significant for most fracture subtypes except pelvic and wrist fractures and observed for both NMSC subtypes, squamous cell carcinoma and basal cell carcinoma. Older people with osteoporotic fractures may have had lifestyles linked to lower cumulative sunlight exposure. Achieving a balance between adequate lifetime sun exposure and protection against its adverse effects (such as fractures and skin cancer) may require assessment of individual risks.

Evolution of Drift-Free, High Power 4H-SiC PiN Diodes

The PiN diode is an attractive device to exploit the high power material advantages of 4H-SiC. The combination of high critical field and adequate minority carrier lifetime has enabled devices that block up to 20 kV and carry 25 A. Furthermore, these devices exhibit fast switching with less reverse recovery charge than commercially available Si PiN diodes. The path to commercialization of the 4H-SiC PiN diode technology, however, has been hampered by a fundamental problem with the forward voltage stability resulting from stacking fault growth emanating from basal plane screw dislocations (BPD). In this contribution, we highlight the progress toward producing stable high power devices with sufficient yield to promote commercial interest. Two independent processes, LBPD1 and LBPD2, have been shown to be effective in reducing the BPD density and enhancing the forward voltage stability while being compatible with conventional power device fabrication. Applying the LBPD1 and LBPD2 processes to 10 kV (20 A and 50 A) 4H-SiC PiN diode technology has resulted in a dramatic improvement in the total device yield (forward, reverse, and forward drift yields) from 0% to >20%. The LBPD1 process appears to be more robust in terms of long term forward voltage stability.

Amorphous Metallic Plastic

We report cerium-based bulk metallic glasses with an exceptionally low glass transition temperature Tg, similar to or lower than that of many polymers. We demonstrate that, in near-boiling water, these materials can be repeatedly shaped, and can thus be regarded as metallic plastics. Their resistance to crystallization permits extended forming times above Tg and ensures an adequate lifetime at room temperature. Such materials, combining polymerlike thermoplastic behavior with the distinctive properties of metallic glasses, are highly unusual for metallic alloys and have great potential in applications and can also facilitate studies of the supercooled liquid state.

Lifetime estimation of a covered overhead line conductor

The paper presents results of studies concerning wind-induced aeolian vibration and fatigue of a 110 kV covered conductor overhead line. Self-damping measurement techniques are discussed: power method is found to be the most reliable technique. A method for compensating tension variations during the self-damping test is presented. Generally used empirical self-damping power models are enhanced and the different models are compared with each other. The Energy Balance Analysis (EBR) is used to calculate the aeolian vibration amplitudes, which thereafter are converted to bending stress for the calculation of conductor lifetime estimate. The results of EBA are compared with field measurements, Results indicate that adequate lifetime estimates are produced by EBA as well as field measurements. Generally the EBA gives more conservative lifetime expectancy. This is believed to result from the additional damping existing in true suspension structures not taken into account by EBA. Finally, the correctness of the line design is verified using Cigre`s safe design tension approach.

A constitutive model for anisotropic materials based on Neuber’s rule

Phenomenological approaches to fatigue damage prediction often rely on the assessment of local stress–strain concentrations in structural components. To avoid complex plastic analysis in fatigue assessment, approximate constitutive models have been developed to evaluate the local inelastic response of the material and which allow for an adequate lifetime prediction in a competitive time. One of these approximate methods is the Neuber rule, which has originally been elaborated for the uniaxial loading state of isotropic materials. This paper addresses an approximate method for multiaxial loading of anisotropic materials. The proposed approach is based on a tensorial formulation of the Ramberg–Osgood equation and a generalization of the uniaxial Neuber hypothesis by assuming the equivalence of the deviatoric strain energy density for the elastic and inelastic solution in the notch region. After a decomposition of the stress tensor into a normalized direction tensor and a stress invariant, a nonlinear expression is obtained which can be iterated for the unknown inelastic stress state. It is shown that the proposed anisotropic Neuber rule includes the multiaxial isotropic and the classical uniaxial formulation as special cases. Furthermore, aspects of parameter identification are discussed for directionally solidified Nickel-based superalloys with transverse isotropic properties and single crystal materials with cubic anisotropy. Two numerical examples demonstrate the applicability of the proposed approach.

Erosion Resistance of Carbon-Carbon Ion Optics

A principal consideration in the design of ion thrusters for spacecraft propulsion is erosion of the downstream grid in the ion optics. Achieving adequate lifetime (10,000 h or more for many potential missions) without grid wear-through can impose signiŽ cant constraints on thruster performance. The conventional material for making ion thruster grids is molybdenum. It is predicted that the wear rate of grids made of carbon–carbon composite should be one-eighth to one-ninth that of molybdenum grids. A pair of tests of carbon–carbon and molybdenum grids were conducted under nearly identical operating conditions to determine if carbon–carbon would exhibit the expected resistance to erosion.The result matched theprediction. Someuncertainty in thedata,however, precluded a fully deŽ nitive veriŽ cation. Also, a procedural investigation showed that presence of oxygen, water vapor, and nitrogen greatly increases the carbon–carbon erosion rate.

Spectroscopic evaluation of n-type CdZnTe gamma-ray spectrometers

This work focuses on the evaluation of the spectroscopic performance of n-type CdZnTe gamma-ray spectrometers, grown by a modified horizontal Bridgman Technique developed at IMARAD Imaging Systems Ltd. Two types of devices are studied: (i) detector arrays grown and produced by IMARAD and employing ohmic indium contacts and (ii) detectors and arrays fabricated at Technion in crystals provided by IMARAD, employing different types of contacts. Alpha particle spectroscopy as well as gamma-ray spectroscopy is used to evaluate and characterize the energy resolution of gamma-ray spectrometers fabricated on n-type CdZnTe grown by a modified horizontal Bridgman and doped with indium. The electron and hole mobility lifetime products of the n-type CdZnTe material grown by IMARAD are estimated by measuring the dependence of charge collection efficiency upon the bias voltage, using a calibrated multichannel analyzer. The measured results indicate that the average electron and hole mobility-lifetime products are, respectively, of the order of μnτn=(1–2)·10−3 cm2/V and μpτp=6·10−6 cm2/V. The measured energy resolution of 122 keV photons is −(5–6)% when the source is not collimated and is reduced to −4.5% when the source is collimated. These results are obtained with ohmic cathode as well as with a rectifying cathode. A statistical model for the calculation of the pulse height spectra as a function of photon energy, electron and hole mobility-lifetime products and applied electric field, which has been recently reported in Applied Physical Letters, is used to determine the role of incomplete charge collection in the spectral performance of the n-type CdZnTe spectrometers. The comparison between the measured and modeled results indicates that the dark noise, cross talk and non-uniformity are the main limiting factors of the spectral performance of the n-type spectrometers rather than incomplete charge collection. The good spectroscopic performance of the arrays under study is attributed to an adequate hole mobility lifetime for the geometry of the pixilated arrays. The study indicates that the n-type CdZnTe spectrometers are useful for a wide range of imaging applications.

Development path of low aspect ratio tokamak power plants

Recent advances in tokamak physics indicate that a spherical tokamak may offer a magnetic fusion development path that can be started with a small size pilot plant and progress smoothly to larger power plants. Full calculations of stability to kink and ballooning modes show the possibility of greater than 50% β-toroidal with the normalized β [ β N= β T/(I/aβ)] as high as 10 and fully aligned 100% bootstrap current. Such β-values coupled with 2–3 T toroidal fields imply a pilot plant about the size of the present DIII-D tokamak could produce ∼800 MW thermal, 160 MW net electric, and would have a ratio of gross electric power over recirculating power ( Q PLANT) of 1.9. The high β values in the ST mean that E×B shear stabilization of turbulence should be ten times more effective in the ST than in present tokamaks, implying that the required high quality of confinement needed to support such high beta values will be obtained. The anticipated β values are so high that the allowable neutron flux at the blanket sets the device size, not the physics constraints. The ST has a favorable size scaling so that at 2–3 times the pilot plant size the Q PLANT rises to 4–5, an economic range and 4 GW thermal power plants result. Current drive power requirements for 10% of the plasma current are consistent with the plant efficiencies quoted. The unshielded copper centerpost should have an adequate lifetime against nuclear transmutation-induced resistance change and the low voltage, high current power supplies needed for the 12-turn TF coil appear reasonable. The favorable size scaling of the ST and the high β mean that in large sizes, if the copper TF coil is replaced with a superconducting TF coil and a shield, the advanced fuel D-He 3 could be burned in a device with Q PLANT∼4. If the anticipated physics of the ST regime can be proven in near-term experiments and engineering challenges (such as the high power density to be exhausted and centerpost neutronics issues) can be met, then the ST offers the possibility of a magnetic fusion development path with a minimal cost initial step and exciting further possibilities.

Point of Use HF Purification for Silicon Surface Preparation by Ion Exchange

The point of use (POU) HF purification performance of an ion exchange membrane (IEM) is evaluated in this paper. First, no cationic extractable (i.e., Cu, Fe, and Ni) from two IEMs was detected in HF 0.5% which makes these membranes compatible with sub‐ppb grade HF. The IEM purification performance was evaluated with 0.5% HF spiked with 10 ppb of Fe, Ni, and Cu nitrates. The results show that after less than five turnovers through an IEM, the impurity concentration drops below 1 ppb. The decrease rate can be fitted to a model assuming the experimental tanks to be continuously stirred tank reactors and that the impurity concentration after the membrane is a function of the single‐pass purification efficiency of the IEM, the concentration before purification, and the metals desorbed from the IEM. The concentration after purification was investigated up to a cumulative Fe loading of 300 ppb in the 23 liter recirculated loop. It increases linearly vs. cumulative loading and can be explained by the Langmuir theory resulting in a purification efficiency at the equilibrium of close to 99.5% in this loading regime. This suggests that the capacity of the membrane is high enough to ensure an adequate lifetime. Finally, a POU IEM can reduce the Cu concentration in the bath resulting in less Cu outplating. No impact was noticed on particle and organic deposition, on surface roughness, and on 5 nm gate oxide integrity.

Engineering and design aspects related to the development of the ITER divertor

The adaptation of the high-recycling divertor concept for ITER is not possible because, owing to the increase in fusion power to 1.5 GW, the resulting loads on the divertor target plates are in excess of 35 MW m−2. Therefore a novel concept is proposed, based on observations of power reduction by about one order of magnitude in existing tokamaks at high-density operation. It will allow for a viable approach to the problems of energy and particle exhaust, helium pumping and impurity control at an adequate lifetime of the divertor. The concept is based on radiation and momentum exhaust along the divertor channel, and relies on the fact that a substantial fraction of the incoming power can be radiated as long as the plasma pressure is balanced not only by plasma and neutral particles in front of the target plates but also dynamically by high fluxes of recycling particles. Therefore this operating regime is called the dynamic gas target divertor. This paper describes the design and the development of the ITER divertor and shows how the physics requirements have been translated into engineering solutions, and how the additionally existing constraints (such as the space limitations, neutron effects, electromagnetic loads, compatibility with other components, easy maintainability, etc.) have been taken into account.