Simulated Laboratory Conditions Research Articles

Already a short-term soils exposure to the field-rate glufosinate concentration significantly influences soil bacterial communities

The early impact of glufosinate derived herbicide Basta® 15 on bacterial communities of two different soils never exposed to this herbicide was investigated using cultivation approach and non-cultivation based denaturing gradient gel electrophoresis (DGGE) analysis of amplified 16S rRNA genes. Under the simulated laboratory conditions glufosinate treatment increased numbers of total cultivable heterotrophic bacteria in both tested soils. Surprisingly even the lowest glufosinate concentration (1 mmol) significantly affected bacterial community composition in both tested soils and original populations were replaced by new ones upon the 2 days glufosinate treatment. In nutrient rich Haniska soil the effect was dose dependent and glufosinate treatment decreased genetic diversity of bacterial population. In nutrient poor KaÄžava soil the highest glufosinate concentration (16 mmol) increased the diversity of bacterial population probably as a result of carbon source supplementation. Glufosinate treatment selected Gram-negative bacteria in both soils. Two species of Enterobacter genus were found to be dominant in glufosinate treated Haniska soil and Pseudomonas beteli and Brevundimonas diminuta were found to be dominant in glufosinate treated KaÄžava soil using non-cultivation based DGGE method. Our data indicated that under the simulated soil conditions the soil bacterial community was significantly affected even by a short-term exposure to glufosinate.

Metabolism and dissipation kinetics of a novel protoporphyrinogen IX oxidase herbicide [oxadiargyl] in various buffered aqueous system under laboratory-simulated condition.

Present investigation was carried out using two commercial products Raft (oxadiargyl 6% EC) and Topstar (oxadiargyl 80% WP) of Oxadiargyl {5-tert-butyl-3[2,4-dichloro-5-(prop-2-ynyloxy)phenyl]-1,3,4-oxadiazol-2 (3H)-one} to investigate the persistence behavior and metabolism of the herbicide in various aqueous system under different pH condition. Half-life values revealed that alkaline hydrolysis played a dominant role in hydrolytic degradation of this compound. Q-ToF micromass study with the alkaline fractions of oxadiargyl indicated the formation of five metabolites, which was further characterized from their mass fragmentation data. The nature of metabolites formed indicated that heterocyclic oxadiazoline ring cleavage was found to be the main pathway of hydrolytic transformation of oxadiargyl.

Evaluation of zinc accumulation, allocation, and tolerance in Zea mays L. seedlings: implication for zinc phytoextraction.

This work investigated the accumulation, allocation, and impact of zinc (Zn; 1.0 μM-10 mM) in maize (Zea mays L.) seedlings under simulated laboratory conditions. Z. mays exhibited no significant change in its habitus (the physical characteristics of plants) up to 10-1000 μM of Zn (vs 5-10 mM Zn). Zn tolerance evaluation, based on the root test, indicated a high tolerance of Z. mays to both low and intermediate (or relatively high) concentrations of Zn, whereas this plant failed to tolerate 10 mM Zn and exhibited a 5-fold decrease in its Zn tolerance. Contingent to Zn treatment levels, Zn hampered the growth of axial organs and brought decreases in the leaf area, water regime, and biomass accumulation. Nevertheless, at elevated levels of Zn (10 mM), Zn(2+) was stored in the root cytoplasm and inhibited both axial organ growth and water regime. However, accumulation and allocation of Zn in Z. mays roots, studied herein employing X-ray fluorimeter and histochemical methods, were close to Zn accumulator plants. Overall, the study outcomes revealed Zn tolerance of Z. mays, and also implicate its potential role in Zn phytoextraction.

Influence of pore pressure on tensile fracture growth in rocks: a new explanation based on numerical testing

The diffusion of pore fluid pressures may create both spatial and temporal effective stress gradients that influence or control the development and evolution of fractures within rock masses. To better understand the controls on fracturing behavior, numerical simulations are performed using a progressive fracture modeling approach that shares many of the same natural kinematic features in rocks, such as fracture growth, nucleation, and termination. First, the pinch-off breaking test is numerically performed to investigate the tensile failure of a rock specimen in a uniform pore pressure field. In this numerical simulation, both mechanical and hydrological properties of a suite of rocks are measured under simulated laboratory conditions. The complete tensional failure process of the rock specimen under pore pressure was reproduced. Second, a double-notched specimen is numerically extended to investigate how the water flow direction or pore pressure gradient influences the fracture growth. An exhaustive sensitivity study is conducted that examines the effects of varying both hydrological and mechanical boundary conditions. The simulation results indicate that local fluid pressure gradients strongly influence the state of stress in the solids and, thereby, fracture growth. Fracture and strength behavior is influenced not only by the pore pressure magnitude on a local scale around the fracture tip, but also by the orientation and distribution of pore pressure gradients on a global scale. Increasing the fracture growth rate increases the local model permeability and decreases the sample strength. The results of this study may provide useful information concerning the degree of hydrological and mechanical coupling action under geologic conditions.

The efficiency, energy intensity and visual impact of the accent lighting in the retail grocery stores

Over the last few years, topics of displaying, presentation, lighting, energy saving and issues related to the environment while selling the fresh food (fruits, vegetable, bakery products, meat) are becoming an important matter among traders. However, just bigger companies with transnational capital have devoted their attention to this issue yet. Generally, the energy costs make up 70% of operating costs in retail stores where the cooling system and lighting are the most energy consuming. Accent lighting in modern retails is largely involved in the overall design and atmosphere in shops and plays a crucial role in presenting the goods as well. Using of accent lighting can draw the customer's attention to a specific part of the sales area and achieve the overall harmonization in the store. With the rational using of combination of energy saving and effective accent lighting retailers can achieve not only attractive presentation of displayed products but also appreciable savings in the operation of their stores. It is the only factor that can be exactly measured and controlled. Using a Colour and Lux Meters we found out the intensity and color temperature of accent lighting used in domestic and foreign retail chains for the different kinds of fresh food products. Based on the obtained values we have compiled graphs, which are showing visual comfort. We also identified different types of accent lighting, which we assigned to their impact on emotional involvement of consumers. The starting points were the tests we conducted in simulated laboratory conditions. While searching of a compromise between effective and energy efficient accent lighting we take into consideration consumers' emotional response as well as the annual electricity consumption of different types of light sources. At the end we recommend options for energy-efficient, effective and spectacular lighting while using the optimal number of light sources and their logical organization, automatic control as well as using energy-saving LED lights or practical skylights. Improvements in energy efficiency of technical equipments could reduce the operating costs for retailers as well as enhance the attractiveness of displayed goods and customer satisfaction and thereby increase their sales.

Prediction of the Static Modulus of Elasticity Using Four non Destructive Testing

The static modulus of elasticity (Es) is an important parameter in the analysis of hydraulic concrete structures, changes have been made to the regulation of construction; these changes require minimum values for the Es, so now, in addition to concrete compressive strength (f´c) also Es values should be ensured. A methodology to predict Es is proposed, specifically, the Es were modeled by testing: ultrasonic pulse velocity (UPV), electrical resistivity test (ERT), resonance frequency test (RFT), the Hammer Test Rebound (HTR) and f´c. In order to generate models multiple linear regression technique was used. Cylindrical specimens were prepared in two stages, in the first stage was simulated laboratory conditions in the second stage was simulated conditions of concrete made in situ. All cylinders were subjected to non-destructive and destructive tests at different ages. The research objective is to predict Es from the results of destructive tests (traditionally employed to obtain Es) and nondestructive testing. It was possible to obtain a model whose correlation coefficient indicates the good approximation in the generated predictions.

MOONLIGHT: A NEW LUNAR LASER RANGING RETROREFLECTOR AND THE LUNAR GEODETIC PRECESSION

Since the 1970s Lunar Laser Ranging (LLR) to the Apollo Cube Corner Retroreflector (CCR) arrays (developed by the University of Maryland, UMD) supplied almost all significant tests of General Relativity (Alley et al., 1970; Chang et al., 1971; Bender et al.,1973): possible changes in the gravitational constant, gravitational self-energy, weak equivalence principle, geodetic precession, inverse-square force-law. The LNF group, in fact, has just completed a new measurement of the lunar geodetic precession with Apollo array, with accuracy of 9 × 10−3, comparable to the best measurement to date. LLR has also provided significant information on the composition and origin of the moon. This is the only Apollo experiment still in operation. In the 1970s Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo CCR arrays dominate the error budget. With the project MoonLIGHT (Moon Laser Instrumentation for General relativity High-accuracy Tests), in 2006 INFN-LNF joined UMD in the development and test of a new-generation LLR payload made by a single, large CCR (100mm diameter) unaffected by the effect of librations. With MoonLIGHT CCRs the accuracy of the measurement of the lunar geodetic precession can be improved up to a factor 100 compared to Apollo arrays. From a technological point of view, INFN-LNF built and is operating a new experimental apparatus (Satellite/lunar laser ranging Characterization Facility, SCF) and created a new industry-standard test procedure (SCF-Test) to characterize and model the detailed thermal behavior and the optical performance of CCRs in accurately laboratory-simulated space conditions, for industrial and scientific applications. Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP) and the temperature distribution of retroreflector payloads under thermal conditions produced with a close-match solar simulator. The apparatus includes infrared cameras for non-invasive thermometry, thermal control and real-time payload movement to simulate satellite orientation on orbit with respect to solar illumination and laser interrogation beams. These capabilities provide: unique pre-launch performance validation of the space segment of LLR/SLR (Satellite Laser Ranging); retroreflector design optimization to maximize ranging efficiency and signal-to-noise conditions in daylight. Results of the SCF-Test of our CCR payload will be presented. Negotiations are underway to propose our payload and SCF-Test services for precision gravity and lunar science measurements with next robotic lunar landing missions. In particular, a scientific collaboration agreement was signed on Jan. 30, 2012, by D. Currie, S. Dell’Agnello and the Japanese PI team of the LLR instrument of the proposed SELENE-2 mission by JAXA (Registered with INFN Protocol n. 0000242-03/Feb/2012). The agreement foresees that, under no exchange of funds, the Japanese single, large, hollow LLR reflector will be SCF-Tested and that MoonLIGHT will be considered as backup instrument.

Observations of chloride ingress and calcium oxychloride formation in laboratory concrete and mortar at 5 °C

The combination of chloride deicer exposure and temperatures near the freezing point of water makes for an aggressive environment for many concrete pavements and bridge decks. In laboratory-simulated conditions, the formation of calcium oxychloride hydrate (3CaOCaCl215H2O or 3CaOCaCl212H2O) phases has been associated with the expansion and deterioration of concrete and mortar, but calcium oxychloride phases have yet to be observed in the field. A decomposition path from calcium oxychloride hydrate to CaCl2Ca(OH)22H2O to calcite CaCO3 is proposed here, and offered as an explanation for the lack to date of convincing field evidence for a calcium oxychloride hydrate deterioration mechanism.

Tribological behavior of sugar mill roller shaft in laboratory simulated conditions

Wear is often observed on top roll shaft journal surface. Sugar mill roller shafts are made up of carbon steel EN8. The friction and wear behavior of carbon steel EN8 was investigated under dry, lubricated, and contaminated sliding conditions. Sugar cane juice, bagasse, and water were used to simulate the contaminated service conditions. A reciprocating pin on disk tester was used to carry out friction and wear tests. EN8 was flat surface whereas E52100 bearing ball was counterface. The friction characteristics were examined at a constant applied load and sliding speed. It was observed that the coefficient of friction and wear volume increased when the shaft material was slid in contaminated test conditions. The volumetric wear was determined to analyze the wear resistance of the shaft material in the extreme service environment. Optical and scanning electron microscopy study showed sever wear in dry and contaminated test conditions. It was observed that the cracks initiated on the surface are consequences from the tribological phenomenon at the sliding interface.

An experimental determination of the H2S overall mass transfer coefficient from quiescent surfaces at wastewater treatment plants

This study has investigated overall mass transfer coefficients of hydrogen sulphide from quiescent liquid surfaces under simulated laboratory conditions. Wind flow (friction velocity) has been correlated with the overall mass transfer coefficient (KL) of hydrogen sulphide in the liquid phase using a wind tunnel study. The experimental values for this coefficient have been compared with predicted KL values obtained from three different emission models that are widely used to determine volatilization rates from the quiescent surfaces of wastewater treatment unit processes. Friction velocity (in a range of 0.11 and 0.27 m s−1) was found to have a negligible influence on the overall mass transfer coefficients for hydrogen sulphide but by contrast two of the models predicted a stronger influence of friction velocity and overestimate the KL values by up to a factor of 12.5, thus risking unnecessary expenditure on odour control measures. However, at low wind speeds or friction velocities, when more odour complaints might be expected due to poor atmospheric dispersion, a better agreement of emission rates with experimental data was found for all the models.

A comparative investigation of the degradation of pyrite and pyrrhotite under simulated laboratory conditions

The effect of the oxidation of iron sulfides contained in aggregates on concrete durability is well known. The mechanisms of formation of gypsum or ettringite have been well documented for a long time and also, for about 15years, the formation of thaumasite although there are some unanswered questions concerning this compound, such as whether the ettringite is always needed as a precursor to thaumasite.However, there are few studies on behavioral differences of different oxidizable sulfides in the process of oxidation with more or less harming effects on concrete durability. As a result there is some confusion in the various standards of aggregates for concrete. The American Standard ASTM C294-05 (Section No. 13) does not make any distinction between the different sulfide types: marcasite, pyrite or pyrrhotite. In contrast, the European standard EN 12620:2008 specifically in paragraph 6.3.2 says that it is necessary to take special precautions if it detects the presence of pyrrhotite (an unstable form of iron sulfide FeS). Once confirmed of their presence the maximum total sulfur content is less than 0.1%. This amount is 10 times lower than would be permitted for aggregates containing other iron sulfides. This fact is exaggerated from the point of view of many engineers and could result that in practice, suitable aggregates have been rejected unnecessarily on some sites.This technical note presents the findings of a first experimental set-up that serves to analyze the products of an aqueous solution with constant oxygen supply in two pyrite and pyrrhotite samples as well as the physicochemical pH and electrical potential values of the solutions. The results show the existence of significant differences regarding the nature of the alteration products proving that the pyrrhotite is degraded more than the pyrite. In a second experimental set-up, the oxidation of both iron sulfides has been analyzed but three aggregate types coming from three different rocks were added: a marlstone, a limestone and a shale. In all three cases reveal that pyrrhotite is degraded more than pyrite.Despite the limitations in the representativity of this study in such a huge context, the results of this study permit some first reflections to be made about the normative that rules the characterization and quantification of sulfur compounds in concrete aggregates.

Degradation dynamics of an oxime carbamate insecticide (methomyl) in aqueous medium of varying pH under laboratory simulated condition

Laboratory degradation studies were performed in water at pH 4.0, 7.0 and 9.2 using methomyl (Lannate 12.5 L) formulation at the rates of 1.0 (T1) and 2.0 (T2) µgmL-1. Water samples collected on 0 (2 h), 3, 7, 15, 30, 45, 60 and 90 days after treatments were processed for residue analysis of methomyl by HPLC equipped with Photo Diode Array Detector. In 60 days, dissipation was 84-87% at pH 4.0, 71-77% at pH 7.0, and 91-93% at pH 9.2 in both treatments showing very little effect of pH on dissipation. The half-life periods observed were 20.76 and 22.13 days at pH 4.0, 27.87 and 28.67 days at pH 7.0 and 15.84 and 16.54 days at pH 9.2 at T1 and T2 doses respectively.

Effect of pH on the fate of fenazaquin in soil and water under laboratory-simulated condition

The persistence of fenazaquin (4-t-butylphenylethyl quinazolin-4-yl ether) was studied in three different soils, namely, Gangetic alluvial (pH 6.9), laterite (pH 5.3), and terai (pH 5.1) soil and in water at three different pH values (4.0, 7.0, and 9.2) under laboratory-simulated condition and samples were analyzed upto 60 days at regular intervals. Fenazaquin was applied at 5 and 10 µg g−1 for each soil and at 0.2 and 0.4 µg mL−1 to each water sample. Dissipation of fenazaquin in soil and water followed first-order kinetics irrespective of any treatments. The half-life of fenazaquin was found in the range of 47–64 days in soils and 3.49–37.6 days in water irrespective of dose. The persistence of fenazaquin in soil significantly increased in the order of Gangetic alluvial soil (pH 6.9) > laterite soil (pH 5.3) > terai soil (pH 5.1), whereas in water the trend of persistence was pH 9.2 ≥ pH 7.0 > pH 4.0. The dissipation of fenazaquin in soil and water was found to be dependent on pH irrespective of doses.

Photolysis of the herbicide bispyribac sodium in aqueous medium under the influence of UV and sunlight in presence or absence of sensitizers

The photolysis of a rice herbicide Bispyribac sodium (Sodium 2, 6-bis [(4, 6-dimethoxypyrimidin-2-yl) oxy] benzoate) has been studied in different aqueous medium (distilled water, pond water and Irrigation water) under the influence of UV (λ max ≥ 250 nm) and sunlight in presence or absence of sensitizers (TiO2 and KNO3). The study was conducted under laboratory simulated condition which made it possible to evaluate the contribution of different factors viz. source of irradiation, solvent and sensitizers towards the photolysis of bispyribac sodium. The photodegradation proceeds via first order reaction Kinetics in all the cases. Five photo metabolites (M1-M5) were isolated in pure form by column chromatographic method from the irradiation system under UV influenced and TiO2 as sensitizer. From the different spectral data (IR, NMR, UV-VIS, Mass) the structure of these five metabolites were assigned as M1 (Phenol), M2 [2, 6-Dihydroxy benzoic acid], M3 [2, 6-bis [(4, 6 dimethoxypyrimidin-2yl) oxy] benzoic acid], M4 [2-(3-Hydroxy-phenoxy)-pyrimidine-4, 6-diol] and M5 as [2,4-Dihydroxy-3, 5-dimethoxy-6-(4-methoxy pyrimidine-2-yloxy)-benzoic acid]. Moreover, another six photometabolites (M6-M11) were identified from the different irradiation system on the basis of Micromass analysis. On the basis of MS/MS data analysis, the structure of these six photometabolites were assigned as M6 [2-(4, 6-Dimethoxy-pyrimidin-2-yloxy)-6-hydroxy-benzoic acid], M7 [2-Hydroxy-6-(4-hydroxy-6-methoxy-pyrimidin-2-yloxy)-benzoic acid], M8 [4, 6-Dimethoxy-pyrimidin-2-ol], M9 [6-Methoxy-pyrimidine-2, 4-diol], M10 [2-Hydroxy-6-(pyrimidin-2-yloxy)-benzoic acid] and M11 [2, 4, 6-Trimethoxy-pyrimidine]. The plausible Photodegradation pathways of bispyribac sodium in the present investigation were portrayed which proceeds via hydrolysis, hydrolytic cleavage, O-dealkylation, decarboxylation, dehydroxylation, O-alkylation and hydroxylation.

The behaviour of consolidated volcanic tuffs: weathering mechanisms under simulated laboratory conditions

Five volcanic tuffs ranging from dacitic tuffs of Hungary to rhyolite, phonolite and basaltic tuffs of Germany were consolidated under laboratory conditions. Prior to consolidation an anti-hygro, a hydrous consolidant, which reduces the swelling ability of clay minerals, was applied. The three consolidants, a silicic acid ester (SAE), an elastic silicic acid ester (eSAE) and an acrylate resin (PMMA) were applied on test specimens under vacuum. Petrographic characterisation (polarizing microscopy, XRD, SEM) provided data for fabric analyses and the mineral composition of the tuffs. Changes in fabric, effective porosity, density, tensile strength, ultrasonic wave velocity were evaluated after the treatment. Weathering simulation tests such as hygric dilatation and thermal dilatation aimed to prove the effectiveness of consolidation and the durability of consolidated tuff samples. More than 500 samples were analysed. The tests showed that SAE caused the highest increase in indirect tensile strength. The water absorption and the pore size distribution of the tuffs were modified by consolidation. The PMMA reduced the water absorption the most, whereas SAE modified it the least. All the tested consolidants increased the thermal dilatation of the tuffs. The changes in hygric dilatation were not uniform: for most tuffs SAE increased and PMMA decreased the hygric dilatation, although the clay-rich Habichtswald tuff showed the opposite trend. The changes in hygric and thermal behaviour of consolidated tuff require special care when specific consolidants are chosen. These products modify the physical properties of consolidated tuffs and change the behaviour of weathering.

Deformation analysis of large aerospace components during assembly

The civil aircraft industry often assembles large deformable aluminium components within the fuselage and wing structures. Part-to-part assembly of these compliant components regularly causes difficulties associated with dimensional variations. This paper describes a methodology to predict overall deformation between the alignment of the rib foot and the skin panel. The assembly operations and conditions encountered on the real production jigs were conducted under simulated laboratory conditions. A table method for prediction was developed to reduce uncertainties in positioning between the skin panel and rib foot. Finite element model of the rib was created to further enhance the prediction method. Results obtained from the predicted method were evaluated against real factory data. The validation performed against the assembly plant showed good performance of the prediction method in forecasting the positional variations occurring during the simulation of the assembly. The prediction method was, therefore, proven to be reliable.

Assessment of aliphatic–aromatic copolyester biodegradable mulch films. Part II: Laboratory simulated conditions

In a previous paper, we demonstrated that the main mechanism of degradation of poly(butylene adipate- co-terephthalate) (PBAT) biodegradable mulch films when exposed to field conditions was crosslinking due to the photodegradation from solar radiation. The aim of this work was to determine the effect of crosslinking on the biodegradability of PBAT samples. PBAT films were subjected to UV photodegradation in laboratory simulated conditions to investigate the effects of crosslinking and other major changes in the structure and mechanical properties of the films. Crosslinking caused the films to become more brittle and produced a reduction of the tensile strength and percent elongation. Besides the crosslinking degradation mechanism, chain scission also occurred in the samples. After 45 d of biodegradation test, the non-crosslinked PBAT sample reached 60% of mineralization. However, the percent mineralization was reduced when samples were crosslinked. The percent mineralization of samples with 10%, 30%, 50%, and 70% gel content was 36%, 43%, 21%, and 24%, respectively. Our results indicate that crosslinking is a key process underlying the degradation of the PBAT film and did affect the biodegradability of the films, since the samples with greater amount of gel content generally showed less percent mineralization in the biodegradation tests.

The Effect of High-Impact Sports on Total Knee Arthroplasties

Orthopedic surgeons continue to discourage high-impact sports after total knee arthroplasty because of the theoretical risk of polyethylene wear. However, increasing numbers of patients are seeking an active lifestyle after surgery, and many are choosing to participate in high-impact sports. Although simulated laboratory conditions have shown high-impact loading can have adverse effects on the durability of total knee arthroplasties, there are no known in vivo studies which specifically analyze conditions in patients participating in high-impact sports activity. The purpose of the present study was to analyze whether the clinical and radiographic results of total knee arthroplasties in patients returning to demanding, high-impact sports activity after surgery differed from those of patients who did not participate in these activities.

Change in expression of apoptosis genes after hyperthermia, chemotherapy and radiotherapy in human colon cancer transplanted into nude mice

To investigate the change in expression of p53, Bcl-2, and Bax genes in human colon cancer cells transplanted into nude mice after hyperthermia, chemotherapy, radiotherapy, thermochemotherapy, thermoradiotherapy and thermochemoradiotherapy. Human colon cancer cell line (HT29) was transplanted into the hind limbs of nude mice. Under laboratory simulated conditions of hyperthermia (43 centigrade, 60 min), the actual radiation doses and doses of mitomycin C (MMC) were calculated in reference to the clinical radiotherapy for human rectal cancer and chemotherapy prescription for colon cancer. The mice were divided into 6 groups according to the treatment approaches: hyperthermia, chemotherapy, radiotherapy, thermochemotherapy, thermoradiotherapy, and thermochemoradiotherapy. The mice were sacrificed at different time points and the tumor tissue was taken for further procedures. The morphologic changes in membrane, cytoplasm and nuclei of tumor cells of p53, Bcl-2, and Bax after treatment, were observed by immunohistochemistry staining. All of the six treatment modalities down-regulated the expression of p53, Bcl-2 and up-regulated the expression of Bax at different levels. The combined therapy of hyperthermia, with chemotherapy, and/or irradiation showed a greater effect on down-regulating the expression of p53 (0.208 +/- 0.009 vs 0.155 +/- 0.0115, P < 0.01) and Bcl-2 (0.086 +/- 0.010 vs 0.026 +/- 0.0170, P < 0.01) and up-regulating Bax expression (0.091 +/- 0.0013 vs 0.207 +/- 0.027, P < 0.01) compared with any single therapy. Hyperthermia enhances the effect of radio- and chemotherapy on tumors by changing the expression of apoptosis genes, such as p53, Bcl-2 and Bax.

Characterisation of high temperature oxide scales for plasma sprayed NiCrAlY coated Ni‐ and Fe‐based superalloys

PurposeTo characterise the high temperature oxide scales for some plasma sprayed NiCrAlY coated Ni‐ and Fe‐based superalloys.Design/methodology/approachNi‐22Cr‐10Al‐1Y metallic coatings were deposited on two Ni‐based superalloys; Superni 601 and Superni 718 and one Fe‐based superalloy; Superfer 800H by the shrouded plasma spray process. Oxidation studies were conducted on uncoated as well as plasma spray coated superalloys in air at 900°C under cyclic conditions for 50 cycles. Each cycle consisted of 1 h heating followed by 20 min of cooling in air. The thermogravimetric technique was used to approximate the kinetics of oxidation. X‐ray diffraction, SEM/EDAX and EPMA techniques were used to analyse the oxide scales.FindingsAll of the coated, as well as the uncoated, superalloys followed an alnost‐parabolic rate of oxidation. The NiCrAlY coating was found to be successful in maintaining its continuous contact with the superalloy substrates in all the cases. The oxide scales formed on the exposed NiCrAlY coated superalloys were found to be intact and spallation‐free. The main phases analysed for the coated superalloys were oxides of nickel, chromium and aluminium and spinel of nickel and chromium, which are expected to be useful for developing oxidation resistance at high temperatures.Practical implicationsThe coated superalloys showed remarkable cyclic oxidation resistance under simulated laboratory conditions. However, it is suggested that these coated superalloys also should be tested in actual industrial environments of boilers and gas turbines, etc. so as to obtain more practical and reliable oxidation data.Originality/valueThe knowledge of the reaction kinetics and the nature of the surface oxide scales formed during oxidation is important for evaluating the alloys for their use and degradation characteristics in high temperature applications such as steam boilers, furnace equipment, heat exchangers and piping in chemical industry, reformer, baffle plates/tubes in fertilizer plants, jet engines, pump bodies and parts.