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Notes: Using time-resolved photoluminescence (PL) measurements, we have studied the exciton localization effect in InGaAs/GaAs quantum wire (QWR) structures formed in corrugated narrow InGaAs/GaAs quantum wells (QWs) grown on (553)B GaAs substrate. The PL decay time in the QWR structure was found to be independent of the temperature for T〈70 K, showing a typical dynamical behavior of the localized excitons. This result is in striking contrast to the corresponding quantum well structures, where a linear increase of the PL decay time was observed. In addition, an increase of the exciton lifetime was observed at low temperature for the QWR structure as compared to a reference InGaAs/GaAs quantum well sample (1200 vs 400 ps). The observed longer decay time was attributed to the reduction in the spatial coherence of excitons in the QWR-like structure. In PL measurements, a significant polarization anisotropy was also found in our narrow InGaAs/GaAs QWs grown on (553)B GaAs. © 2001 American Institute of Physics.

Notes: Solid-state interfacial reaction in the Ni/Nb multilayers upon thermal annealing is investigated with molecular-dynamics simulation. The result shows that amorphization takes place at medium temperatures and the growth of the amorphous interlayer presents an asymmetric behavior due to faster consuming of the Ni layer than the Nb layer. Consequently, a Ni-enriched amorphous phase is formed together with some unreacted Nb before complete amorphization, which agrees well with the experimental observations. Moreover, it is revealed that the Nb lattice can accommodate a large number of Ni atoms and still retain crystalline structure, while a small amount of Nb atoms induce a spontaneous decay of the Ni lattice, which is essentially the physical origin of the asymmetric growth observed in not only the Ni–Nb system but also in the other systems studied so far. © 2000 American Institute of Physics.

Notes: By using molecular dynamics simulation with an n-body Ni–Mo potential, the relative stability of the Ni- and Mo-based solid solutions versus their amorphous counterparts is studied as a function of solute concentrations at 300 K. It is observed that the supersaturated terminal solid solutions have the maximum or critical solute concentrations of 21 at. % of Mo in Ni and 25 at. % of Ni in Mo, respectively, beyond which the solid solutions transform into an amorphous phase. As such, the glass-forming range of the Ni–Mo system is derived to be 21–75 at. % of Mo. The computed critical solute concentrations are compared with those predicted by the generalized Lindemann melting criterion as well as with those revealed by ion-beam mixing/solid-state interdiffusion reaction experiments of Ni–Mo multilayered films. © 2000 American Institute of Physics.

Notes: An unusual phase formation sequence of first quasicrystalline and then amorphous phases was observed in the Fe–Nb and Fe–Ta multilayers upon room temperature 200 keV xenon ion irradiation. The sequential structural evolution was attributed to the gradually destroying of order in the original crystalline lattices with increasing ion dose. © 2000 American Institute of Physics.

Notes: Anomalous structural evolution was induced by room-temperature 200 keV xenon ion irradiation and it results in the formation of various new metastable phases in the equilibrium immiscible Fe–Cu system. First, nanosized quasicrystals were formed in an amorphous matrix through a two-step transition of crystal to amorphous to quasicrystal in Fe70Cu30 multilayered films. The real compositions of the amorphous matrix and quasicrystals were determined to be close to Fe70Cu30 and Fe50Cu50, respectively. Moreover, the same icosahedral phase was also obtained in another similarly designed Fe50Cu50 multilayered sample upon 850 °C thermal annealing, confirming the existence of such a metastable state. Second, amorphous alloys were formed in a composition range of 30–50 at. % of Cu. Third, a Cu-based face-centered-cubic (fcc) solid solution was formed at an alloy composition of about Fe30Cu70 and, interestingly, another fcc structured metastable crystalline phase was obtained at a composition very close to that of Fe50Cu50. A Gibbs free energy diagram of the Fe–Cu system was calculated, with special consideration of excess interfacial free energy stored in the multilayered films, within the framework of Miedema's model and it gives a reasonable thermodynamic explanation to the metastable phase formation observed. The amorphous-to-quasicrystal transition is also discussed in terms of the similarity in the atomic configuration between the icosahedral and amorphous short-range orders. Furthermore, molecular dynamics study showed that Fe and Cu could be mixed on an atomic scale in the metastable phases observed. © 2000 American Institute of Physics.

Notes: In this letter, we present a proposed model for calculating the standard formation enthalpy of binary transition-metal systems by adding a prefactor S(c) to the well-documented formula developed by Miedema. The main idea is to take into account the significant effect of the atomic size difference on the contact surface while two dissimilar metals approaching together. Employing this model, the standard formation enthalpies of some 260 intermetallic compounds were calculated and compared with the experimentally measured data. It was found that the precision of the calculated values by the proposed model could be improved 13%–65% and that statistically, over 95% of the calculated values were in agreement with the experimental ones within an error of ±23 kJ/mol, while employing the Miedema's formula the agreement was about 80%. © 2002 American Institute of Physics.

Notes: According to a recently proposed criterion for solid-state amorphization to take place in a binary metal system, it is necessary to have a negative thermodynamic factor ΔF defined as a Gibbs free energy difference between an amorphous phase and the initial energetic state of the multilayers/or bilayer together with a relevantly large kinetic factor κ correlated to a diffusivity difference between the constituent metals of the system. The criterion is employed to discuss the possibility of solid-state amorphization in five representative Cu-based binary metal systems featuring either positive or negative heat of mixing. It turns out that the prediction based on the above argument for these Cu-based systems is in good agreement with the experimental results observed so far. © 2000 American Institute of Physics.

Notes: In this letter, we report on the integration of epitaxial ferroelectric Pb(Zr, Ti)O3 (PZT) thin films on Si [100] substrates using a SrTiO3 (STO) template layer and a conducting perovskite (La0.5Sr0.5)CoO3 electrode. X-ray diffraction studies reveal both in-plane and out-of-plane alignment of the heterostructure. The epitaxial films show extremely high remnant polarization as well as piezoelectric d33 coefficients compared to textured and untextured polycrystalline films. © 2002 American Institute of Physics.

Notes: Background: Previous studies have shown that the local and systemic upregulation of fibrogenic cytokines and downregulation of antifibrotic cytokine are central to the pathogenesis of oral submucous fibrosis (OSF). The milk from cows immunized with human intestinal bacteria (immune milk) contains an anti-inflammatory component that may suppress the inflammatory reaction and modulate cytokine production. Therefore, it was decided to test whether immune milk may have some beneficial effects on controlling the symptoms and signs in OSF patients.Methods: In this preliminary study, 26 OSF patients who received immune milk treatment (45 g of immune milk powder twice a day) for 3 months and oral habit intervention were included in the experimental group. Another 20 OSF patients who received only oral habit intervention served as the control group.Results: We found that the interincisor distance was significantly improved (≧3 mm of the baseline measurement) in 18 of the 26 (69.2%) OSF patients in the experimental group at exit. However, in the control group none of the OSF patients had an increase in interincisor distance greater than 2 mm. In addition, disappearance or significant improvement of symptoms at exit was observed in 80% (16/20) of the patients with intolerance to spicy foods (P〈0.001) and 72.2% (13/18) of the patients with xerostomia (P〈0.005) in the experimental group, compared with 17.6% (3/17) of the patients with improvement of intolerance to spicy foods and 15.4% (2/13) of the patients with improvement of xerostomia in the control group. Partial regression of concomitant oral leukoplakia or erythroplakia (judged from the size reduction of the lesions) at exit was noted in 71.4% (5/7) of the patients in the experimental group (P〈0.05), compared with none (0/5) of the patients with improvement in the control group.Conclusion: We conclude that oral administration of immune milk leads to significant improvements of symptoms and signs in OSF patients.

Notes: Background:  Previous study has shown a high incidence of autoantibodies including antinuclear (ANA), antismooth muscle (SMA), antigastric parietal cell (GPCA), antithyroid microsomal (TMA), and antireticulin antibodies in a small group of 26 patients with oral submucous fibrosis (OSF). The reasons why some of the OSF patients have high titers of autoantibodies in serum have not been completely explained and no further study on autoantibodies in OSF patients has been done in a large group of patients.Methods:  In this study, we determined the serum levels of ANA, SMA, GPCA, and TMA in a large group of 109 male Taiwanese patients with OSF by an indirect immunofluorescence technique (for ANA, SMA, and GPCA), and by a semiquantitative microtiter particle agglutination test (for TMA). The presence of serum autoantibodies in OSF patients was further correlated with patients' oral habits and the severity of OSF measured by maximum mouth opening (MMO) and sites of involvement.Results:  We found that the frequencies of presence of serum ANA (23.9%), SMA (23.9%), and GPCA (14.7%) in OSF patients were significantly higher than those (9.2, 7.3, and 5.5%, respectively) in healthy control subjects (P 〈 0.01, P 〈 0.005, and P 〈 0.05, respectively). Although the frequency of presence of TMA (5.5%) in OSF patients was also greater than that (2.8%) in healthy control subjects, the difference was not significant (P 〉 0.05). The presence of serum GPCA in OSF patients was significantly associated with daily areca quid (AQ) consumption (P 〈 0.05). The presence of serum ANA in OSF patients associated with daily AQ consumption was of borderline statistical significance (P = 0.066). However, no significant correlations were demonstrated between the presence of serum autoantibodies in OSF patients and other variables of oral habits, MMO, and sites of involvement.Conclusion:  In this study, all the 109 OSF patients had AQ chewing habit and 73.4% of the OSF patients swallowed the ‘juice’ of AQ during the chewing process. The presence of serum GPCA and ANA in OSF patients was associated with daily consumption of AQs. AQ chewing caused mucosal microtrauma, and ulcerations facilitated the diffusion of genotoxic and cytotoxic AQ ingredients into the oral and gastric tissues. Altered autoantigens released from AQ ingredients-damaged cells may induce autoantibody production. Higher frequencies of specific HLA-DR antigens in OSF patients may also help autoantibody production. Therefore, we conclude that the high incidence of autoantibodies in OSF patients may be due to AQ chewing habit, toxic AQ ingredients, and genetic susceptibility of the OSF patients.