Thermal Cycling (thermal + cycling)

Distribution by Scientific Domains


Selected Abstracts


Anomalous Spin Transition Observed in Bis(2,6-bis(pyrazol-3-yl)pyridine)iron(II) Thiocyanate Dihydrate,

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2003
A. Bhattacharjee
Abstract Bis(2,6-bis(pyrazol-3-yl)pyridine)iron(II) thiocyanate dihydrate undergoes a two-step singlet (1A1) , quintet (5T2) transition in which both steps are associated with thermal hysteresis. Thermal cycling of the sample results in its conversion to a second phase which displays a single-step transition with a very narrow hysteresis loop. This second phase slowly reverts to the initial phase on standing at 300 K. The interconversions are completely reversible. The spin state changes have been monitored by measurement of magnetism and Mssbauer spectra and by differential scanning calorimetry (DSC) studies. [source]


Effectiveness of platinum and iridium in improving the resistance of Ni-Al to thermal cycling in air,steam mixtures

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 6 2008
R. Kartono
Abstract The aim of this work was to assess the value of platinum and iridium additions, with and without hafnium, to binary Ni-Al alloys, intended to act as models for aluminide coatings. Attention was focused on a (,,+,,,) Ni-22Al alloy, but comparisons were made with , -Ni-50Al. All compositions are given in at%. Alloys were exposed to flowing gases at a total pressure of 1 bar for one thousand 1 h cycles at 1200,C. Compared to binary Ni-Al alloys, the Pt-modified alloys performed much better (with or without Hf) in dry air. Thermal cycling in air,+,12% H2O led to more rapid weight losses, due to enhanced spalling. Again, the addition of Pt was beneficial, but weight losses were still significant in the absence of Hf additions. A Ni-22Al-15Pt,+,Hf alloy slowly lost weight by scale spallation over 1000 cycles, but a Ni-22Al-30Pt,+,Hf alloy resisted weight loss. Partial substitution of Ir for Pt was beneficial in both wet and dry air. However, in the case of wet air, Hf additions were necessary to prevent slow spallation losses. [source]


Influence of contamination on resin bond strength to nano-structured alumina-coated zirconia ceramic

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2010
Shanchuan Zhang
Zhang S, Kocjan A, Lehmann F, Kosma, T, Kern M. Influence of contamination on resin bond strength to nano-structured alumina-coated zirconia ceramic. Eur J Oral Sci 2010; 118: 396,403. 2010 The Authors. Journal compilation 2010 Eur J Oral Sci The purpose of this study was to evaluate the influence of contamination and subsequent cleaning on the bond strength and durability of an adhesive resin to nano-structured alumina-coated zirconia ceramic. Zirconia ceramic disks were coated with nano-structured alumina, utilizing the hydrolysis of aluminum nitride powder. After immersion in saliva or the use of a silicone disclosing agent, specimens were cleaned with phosphoric acid etching or with tap water rinsing only. Uncontaminated specimens served as controls. Plexiglas tubes filled with composite resin were bonded with a phosphate monomer [10-methacryloxydecyl-dihydrogenphosphate (MDP)]-containing resin (Panavia 21). Subgroups of eight specimens each were stored in distilled water at 37C, either for 3 d without thermal cycling (TC) or for 150 d with 37,500 thermal cycles from 5 to 55C. The tensile bond strength (TBS) was determined using a universal testing machine at a crosshead speed of 2 mm min,1. The topography of the debonded surface was scrutinized for fractographic features, utilizing both optical and scanning electron microscopy. The TBS to uncontaminated nano-structured alumina-coated zirconia ceramic was durable, while contamination significantly reduced the TBS. Phosphoric acid cleaning was effective in removal of saliva contamination from the coated bonding surface but was not effective in removal of the silicone disclosing agent. Nano-structured alumina coating improves resin bonding to zirconia ceramic and eliminates the need for air-abrasion before bonding. [source]


Load-bearing capacity of all-ceramic three-unit fixed partial dentures with different computer-aided design (CAD)/computer-aided manufacturing (CAM) fabricated framework materials

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2008
Florian Beuer
The purpose of this in vitro study was to compare the load-bearing capacity of posterior three-unit fixed dental prostheses (FDP) produced with three different all-ceramic framework materials: glass-infiltrated alumina (ICA), glass-infiltrated alumina strengthened with zirconia (ICZ), and yttria-stabilized polycrystalline zirconia (YZ). Additionally, the influence on aging of mechanical cyclic fatigue loading and thermal cycling in water were evaluated. A total of 20 frameworks each were fabricated from ICA, ICZ, and YZ by a computer-aided design (CAD)/computer-aided manufacturing (CAM) system. The framework designs were identical for all specimens. All frameworks were veneered with porcelain and cemented with glass,ionomer. Prior to fracture testing, 10 FDP of each experimental group were subjected to thermal and mechanical cycling. Additionally, fractographic analysis was performed. Statistical analysis showed that FDP made from YZ had significantly higher load to failure, whereas no difference was found between the other two materials. Aging did not have a significant effect on the fracture load. [source]


Identification of Quaternary Shape Memory Alloys with Near-Zero Thermal Hysteresis and Unprecedented Functional Stability

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2010
Robert Zarnetta
Abstract Improving the functional stability of shape memory alloys (SMAs), which undergo a reversible martensitic transformation, is critical for their applications and remains a central research theme driving advances in shape memory technology. By using a thin-film composition-spread technique and high-throughput characterization methods, the lattice parameters of quaternary Ti,Ni,Cu,Pd SMAs and the thermal hysteresis are tailored. Novel alloys with near-zero thermal hysteresis, as predicted by the geometric non-linear theory of martensite, are identified. The thin-film results are successfully transferred to bulk materials and near-zero thermal hysteresis is observed for the phase transformation in bulk alloys using the temperature-dependent alternating current potential drop method. A universal behavior of hysteresis versus the middle eigenvalue of the transformation stretch matrix is observed for different alloy systems. Furthermore, significantly improved functional stability, investigated by thermal cycling using differential scanning calorimetry, is found for the quaternary bulk alloy Ti50.2Ni34.4Cu12.3Pd3.1. [source]


The Influence of Alkyl-Chain Length on Beta-Phase Formation in Polyfluorenes

ADVANCED FUNCTIONAL MATERIALS, Issue 1 2009
Daniel W. Bright
Abstract Di- n -alkyl substituted polyfluorenes with alkyl chain lengths of 6, 7, 8, 9, and 10 carbon atoms (PF6, PF7, PF8, PF9, and PF10) are studied in dilute solution in MCH using optical spectroscopy. Beta-phase is formed upon cooling in solutions (, 7,g mL,1) of PF7, PF8, and PF9 only, which is observed as an equilibrium absorption peak at , 437,nm and strong changes in the emission spectra. Beta-phase is formed upon thermal cycling to low temperature in solutions (,7,g mL,1) of PF7, PF8, and PF9, which is observed as an equilibrium absorption peak at , 437,nm and strong changes in the emission spectra. Beta phase is found to occur more favorably in PF8 than in PF7 or PF9, which is attributed to a balance between two factors. The first is the dimer/aggregate formation efficiency, which is poorer for longer (more disordered) alkyl chain lengths, and the second is the Van der Waals bond energy available to overcome the steric repulsion and planarize the conjugated backbone, which is insufficient in the PF6 with a shorter alkyl chain. Beta phase formation is shown to be a result of aggregation, not a precursor to it. A tentative value of the energy required to planarize the fluorene backbone of (15.6,,2.5) kJ mol,1 monomer is suggested. Excitation spectra of PF6, PF7, PF8, and PF9 in extremely dilute (, 10,ng mL,1) solution show that beta phase can form reversibly in dilute solutions of PF7, PF8 and PF9, which is believed to be a result of chain collapse or well dispersed aggregates being present in solution from dilution of more concentrated solutions. PF7, PF8, and PF9 also form beta phase in thermally cycled solid films spin-cast from MCH. However, in the films the PF7 formed a larger fraction of beta phase than the PF9, in contrast to the case in solutions, because it is less likely that the close-packed chains in the solid state will allow the formation of planarized chains with the longer PF9 side chains. [source]


Bismuth,Ceramic Nanocomposites with Unusual Thermal Stability via High-Energy Ball Milling,

ADVANCED FUNCTIONAL MATERIALS, Issue 10 2003
M.A. Meitl
Abstract Electrically conducting nanocomposites of bismuth metal and insulating ceramic phases of SiO2 and MgO were generated via high-energy ball milling for 24 h using zirconia milling media. The resulting nanocomposites contain Bi nanoparticles with sizes down to 5 nm in diameter. The morphology is a strong function of the oxide phase: specifically, the Bi appears to wet MgO while it forms spherical nanoparticles on the SiO2. X-ray diffraction measurements indicate a nominal bismuth grain size of 50 nm, and peak fitting to a simple bidisperse model yields a mixture of approximately 57,% bulk bismuth and 43,% 27 nm diameter crystallites. Nanoparticles as small as 5 nm are observed in transmission electron microscopy (TEM), but may not constitute a significant volume fraction of the sample. Differential scanning calorimetry reveals dramatic broadening in the temperatures over which melting and freezing occur and a surprising persistence of nanostructure after thermal cycling above the melting point of the Bi phase. [source]


Fixed partial dentures: all-ceramics, fibre-reinforced composites and experimental systems

JOURNAL OF ORAL REHABILITATION, Issue 9 2003
M. Rosentritt
Summary, The aim of this in vitro study was to compare the fracture strength of three-unit FPDs (fixed partial dentures) and three-unit inlay FPDs after a simulated 5-year oral wearing period. The restorations were made of a pressable all-ceramic (Empress 2) and two specially designed, experimentally fixed partial dentures combining ceramics with dental composite. Three-unit FPDs and inlay FPDs were manufactured and were adhesively luted onto human molars. After thermal cycling and mechanical loading in an artificial environment, the fracture strength was determined. Zircon-based milled ceramic (Lava) three-unit FPDs were used as a control. The zircon ceramic and the fibre-based ceramic three-unit FPDs showed median fracture values between 1000 and 1400 N. For composite veneered zircon FPDs a fracture strength of about 800 N and for all-ceramic Empress 2 of about 350 N could be determined. The results for the inlay FPDs were between 1300 N and 1400 N for FRC/ceramic, 1000 N for zircon/composite and 500 N for all-ceramic restorations. The all-ceramic showed higher fracture resistance applied as inlay FPDs. The described hybrid techniques combining ceramics and composites could represent an interesting procedure for further investigations and, eventually, clinical implication. [source]


Anelastic Behavior of Plasma-Sprayed Zirconia Coatings

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2008
Yajie Liu
Low-temperature thermal cycling of plasma-sprayed zirconia coatings reveals unique mechanical responses in their curvature measurements, namely nonlinear and cyclic hysteresis, collectively termed as anelastic. These features arise from the inherent layered, porous, and cracked morphology of thermal-sprayed ceramic materials. In this paper, the mechanisms of anelasticity are characterized by crack closure and frictional sliding models, and stress,strain relations of various thermal-sprayed zirconia coatings were determined via an inverse analysis procedure. These results demonstrate process conditions such as powder morphology and spray parameters significantly influence the mechanical behaviors of coatings. The unique anelastic responses can be used as valuable parameters in identifying coating quality as well as process reliability in manufacturing. [source]


Thermal Stability of Lanthanum Zirconate Plasma-Sprayed Coating

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2001
X. Q. Cao
Lanthanum zirconate (La2Zr2O7, LZ) is a newly proposed material for thermal barrier coatings (TBCs). The thermal stability of LZ coating was studied in this work by long-term annealing and thermal cycling. After long-term annealing at 1400C or thermal cycling, both LZ powder and plasma-sprayed coating still kept the pyrochlore structure, and a preferred crystal growth direction in the coating was observed by X-ray diffraction. A considerable amount of La2O3 in the powder was evaporated in the plasma flame, resulting in a nonstoichiometric coating. Additionally, compared with the standard TBC material yttria-stabilized zirconia (YSZ), LZ coating has a lower thermal expansion coefficient, which leads to higher stress levels in a TBC system. [source]


Effectiveness of platinum and iridium in improving the resistance of Ni-Al to thermal cycling in air,steam mixtures

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 6 2008
R. Kartono
Abstract The aim of this work was to assess the value of platinum and iridium additions, with and without hafnium, to binary Ni-Al alloys, intended to act as models for aluminide coatings. Attention was focused on a (,,+,,,) Ni-22Al alloy, but comparisons were made with , -Ni-50Al. All compositions are given in at%. Alloys were exposed to flowing gases at a total pressure of 1 bar for one thousand 1 h cycles at 1200,C. Compared to binary Ni-Al alloys, the Pt-modified alloys performed much better (with or without Hf) in dry air. Thermal cycling in air,+,12% H2O led to more rapid weight losses, due to enhanced spalling. Again, the addition of Pt was beneficial, but weight losses were still significant in the absence of Hf additions. A Ni-22Al-15Pt,+,Hf alloy slowly lost weight by scale spallation over 1000 cycles, but a Ni-22Al-30Pt,+,Hf alloy resisted weight loss. Partial substitution of Ir for Pt was beneficial in both wet and dry air. However, in the case of wet air, Hf additions were necessary to prevent slow spallation losses. [source]


Oxidation behaviour of Fe-Cr-Al alloys during resistance and furnace heating

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 2 2006
H. Echsler
Abstract The behaviour of thin Fe-Cr-Al heating element strips was investigated with respect to the oxidation limited life times and geometrical changes during resistance and furnace heating. For this purpose, isothermal and cyclic oxidation tests varying in their total exposure time and cycle duration were performed in the temperature range 1050,1200 C. Specimens subjected to rapid cyclic, resistance heating revealed shorter life times than calculated for specimens subjected to isothermal exposure. The life times were found to increase with increasing cycle duration and hence decreasing number of cycles for a given time at temperature. This life time decrease is related to an "hour glass" waviness of the specimens, which develops during prolonged thermal cycling. The development of this plastic deformation also occurred during furnace heated, thermal cycling tests. A two-step mechanism is introduced combining an oxidation kinetics related time to the onset of significant waviness with an enhancement of this waviness as a result of a ratcheting effect. The latter seems to strongly depend on the number of cycles and on the plastic deformation generated during each cycle rather than on the total time at temperature. The development of an "hour glass" waviness leads to an enhanced aluminium depletion due to an increase of the specimen surface area. Additional deformation phenomena like "hot tube" or "corkscrew" behaviour occur during the resistance heating tests. These are related to a temperature gradient that develops over the specimen width due to the poor aspect ratio of the specimens. [source]


An investigation of the effect of thermal cycling on plasma-sprayed zirconia/NiCoCrAlY thermal barrier coating

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 1 2004
A. El-Turki
Abstract The microstructural change, crack initiation and spallation of a vacuum plasma sprayed (VPS) thermal barrier coating on an INCONEL-738 superalloy substrate were investigated after successive 300 h thermal cycles at 1050C. The coating was characterised using Raman spectroscopy, scanning electron microscopy (SEM) energy dispersive X-ray analysis (EDX) and Auger electron spectroscopy (AES). Localised micro-cracks at the yttrium (III) oxide stabilised zirconium (IV) oxide (YSZ) ceramic coating/thermally grown oxide (TGO) interface were observed after 8 cycles. Spallation of the YSZ coating occurred after approximately 21 cycles. Significant amounts of the elements titanium, tantalum and chromium were found within the TGO together with the formation of nickel, cobalt and chromium-rich oxides at this TGO/YSZ interface. [source]


Spatially and temporally resolved thermal imaging of cyclically heated interconnects by use of scanning thermal microscopy,,

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 8 2008
Nicholas Barbosa III
Abstract A scanning thermal microscope with a Wollaston probe was used to investigate the spatial distribution and temporal variation of temperature in interconnect structures subjected to thermal cycling. The probe, utilized in passive temperature sensing mode, was calibrated from 20C to 200C using a single-layer aluminum microdevice. Spatial measurements were performed on nonpassivated aluminum interconnects sinusoidally heated by a 6 MA/cm2 current at 200 Hz. The interconnects were determined to have temperatures that decreased with position from a maximum located at the center of both the interconnect length and width. Time-resolved temperature measurements were performed on the same structures sinusoidally heated by a 6 MA/cm2 current at 2 Hz. Both the peak-cycle temperature and average-cycle temperature were found to decrease with increasing distance from the center of the width of the interconnects. Microsc. Res. Tech., 2008. Published 2008 Wiley-Liss, Inc. [source]


Metastability in the resistance of polycrystalline La0.8Li0.2MnO3

PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 5 2009
J. C. Knott
Abstract Bulk polycrystalline La0.8Li0.2MnO3 is found to switch between a low-resistance state and a high-resistance state on thermal cycling. The low-temperature, high-resistance state exhibits strong electroresistance whereas the high-temperature, low-resistance state does not. The change in resistance between the two distinct states is of two orders of magnitude. It is proposed that the observed metastability may serve as the basis for resistive thermal-switching devices. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Highly efficient bismuth telluride doped p-type Pb0.13Ge0.87Te for thermoelectric applications

PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 6 2007
Yaniv Gelbstein
Abstract Bi2Te3 doped p-type Pb0.13Ge0.87Te samples were prepared by hot pressing. We report on very high power factor values of ,30 ,W/cm K2 at 500 C, as were determined from Seebeck coefficient and electrical resistivity measurements. From dilatometric characterization, the phase transition from the low temperature rhombohedral to the high temperature cubic NaCl structures, takes place at 373 C. This transition is accompanied by a continuous and gradual change of the lattice parameters, as was observed by hot stage XRD, suggesting a good mechanical durability upon thermal cycling and operating in large thermal gradients. Rhombohedral distortion of the cubic NaCl structure of Pb1,xGex Te upon cooling, characterized by changes in the interaxial angle , and the lattice parameter. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Effects of cell structure and density on the properties of high performance polyimide foams,,

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2-3 2005
Martha K. Williams
Abstract Activity at the NASA Langley Research Center (LaRC) has focused on developing low density polyimide foam and foam structures which are made using monomeric solutions or salt solutions formed from the reaction of a dianhydride and diamine dissolved in a mixture of foaming agents and alkyl alcohol at room temperature. Monomer blends may be used to make a variety of polyimide foams with varying properties. The first foaming process developed consisted of thermal cycling the polymer precursor residuum and allowing the inflation of the particles to interact to create the foam. This process has resulted in foam structures with higher percentages of open cell content. Another innovative foaming process has been developed that begins with partially inflated microspheres, "friable balloons", with incomplete polymer molecular weight gain, which when fully cured into a foam results in more closed cell structures. In a research study performed by NASA Kennedy Space Center (KSC) and LaRC, two closely related polyimide foams, TEEK-H series and TEEK-L series, (4,4,-oxydiphthalic anhydride/3,4,-oxydianiline and 3,3,,4,4,-benzophenonetetracarboxylic acid dianhydride/4,4,-oxydianiline) were investigated for density effects and closed versus open cell effects on the thermal, mechanical, and flammability properties. Thermal conductivity data under the full range of vacuum pressures indicate that these materials are effective insulators under cryogenic conditions. Contributing factors such as cell content, density, and surface area were studied to determine the effects on thermal conductivity. Cone calorimetry data indicated decreased peak heat release rates for the closed cell system, TEEK-H friable balloons, compared to the TEEK foams with higher open cell content. Mechanical properties including tensile strength and compressive strength indicated that the materials have good structural integrity. Foams with more open cell content resulted in greater tensile and compressive strengths than the closed cell foams. The maximum closed cell content achieved in the "friable balloon" system was 78% at a foam density of 0.048 gm/cm3. Published in 2005 by John Wiley & Sons, Ltd. [source]


Thin-film GaAs epitaxial lift-off solar cells for space applications

PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2005
J. J. Schermer
Abstract In the present work the space compatibility of thin-film GaAs solar cells is studied. These cells are separated from their GaAs substrate by the epitaxial lift-off (ELO) technique and mounted behind a CMG cover glass which at the same time serves as a stable carrier for the thin film cells. In the present initial stage of development these cells have an average efficiency of about 154% under AM0 illumination due to not yet optimized grid contacts and anti-reflection coatings. Inspection after irradiation by 1,MeV electrons, thermal vacuum and thermal cycling experiments reveal that degradation of the cells is largely due to delamination and micro-cracking. Based on these results, glass dehydration and adhesive degassing procedures are implemented in the ELO cell processing. As a consequence, even in this premature phase, newly produced cells show a radiation hardness comparable to or better than that of commercially available GaAs cells on Ge substrates and are virtually unaffected by severe thermal cycling. Copyright 2005 John Wiley & Sons, Ltd. [source]


Groupoid of orientational variants

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 1 2006
Cyril Cayron
Daughter crystals in orientation relationship with a parent crystal are called variants. They can be created by a structural phase transition (Landau or reconstructive), by twinning or by precipitation. Internal and external classes of transformations defined from the point groups of the parent and daughter phases and from a transformation matrix allow the orientations of the distinct variants to be determined. These are algebraically identified with left cosets and their number is given by the Lagrange formula. A simple equation links the numbers of variants of the direct and inverse transitions. The equivalence classes on the transformations between variants are isomorphic to the double cosets (operators) and their number is given by the Burnside formula. The orientational variants and the operators constitute a groupoid whose composition table acts as a crystallographic signature of the transition. A general method that determines if two daughter variants can be inherited from more than one parent crystal is also described. A computer program has been written to calculate all these properties for any structural transition; some results are given for Burgers transitions and for martensitic transitions in steels. The complexity, irreversibility and entropy of fractal systems constituted by orientational variants generated by thermal cycling are briefly discussed. [source]


Stabilization of Taq DNA Polymerase at High Temperature by Protein Folding Pathways From a Hyperthermophilic Archaeon, Pyrococcus furiosus

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2006
Pongpan Laksanalamai
Abstract Pyrococcus furiosus, a hyperthermophilic archaeon growing optimally at 100C, encodes three protein chaperones, a small heat shock protein (sHsp), a prefoldin (Pfd), and a chaperonin (Cpn). In this study, we report that the passive chaperones sHsp and Pfd from P. furiosus can boost the protein refolding activity of the ATP-dependent Cpn from the same hyperthermophile. The thermo-stability of Taq polymerase was significantly improved by combinations of P. furiosus chaperones, showing ongoing protein folding activity at elevated temperatures and during thermal cycling. Based on these results, we propose that the protein folding apparatus in the hyperthermophilic archaeon, P. furiosus can be utilized to enhance the durability and cost effectiveness of high temperature biocatalysts. 2005 Wiley Periodicals, Inc. [source]


Flow cytometric detection of ,- D -glucuronidase gene in wild-type bacterial cells using in-situ PCR

BIOTECHNOLOGY & BIOENGINEERING, Issue 2 2003
Ramaiah Sachidanandham
Abstract An in situ PCR-based flow cytometry method useful for monitoring the presence or absence of the ,- D -glucuronidase gene in Escherichia coli has been developed. A single-step fixation and permeabilization procedure, which maintained cell integrity at the elevated temperatures used during thermal cycling in the presence of PCR reagents, was demonstrated. We have chosen a shorter DNA sequence of length 147 bp for the PCR. Cells subjected to in situ PCR using fluorescein-12-dUTP as a label, showed the presence of uid both in epifluorescence microscopic examination and flow cytometric analysis. Multi-parametric analysis of flow cytometric profiles revealed that the efficiency of labeling was found to be high. The potential of in situ PCR for the detection of uid in intact coliform cells was then successfully tested with a fecal coliform isolated from the coastal waters of Singapore. 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 127,133, 2003. [source]