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Notes: Phase transition in the aperiodic quantum Ising models were studied, in which the transverse magnetic fields are uniform and the couplings are arranged according to the aperiodic sequences that are generated by two types of two-tile inflation rules with initial condition {ApBq}: A → A′=Am11Bm12, B →B′=Am21Bm22, m12, m21≠0, and A → A′=Am11Bm12, B → B′=Bm21Am22, m12, m22≠0. When the inflation rules have the Pisot–Vijayaraghavan (PV) property in number theory, the generated aperiodic systems undergo phase transition at the critical points. When the inflation rules do not have the PV property, it is found that only by changing the initial conditions, the inflation rules can produce aperiodic systems exhibiting phase transition as well as aperiodic systems which do not exhibit any phase transition.

Notes: We have recently shown that both interferon gamma (γ) and interferon alpha-2b (α-2b) markedly depress the expression of messenger RNA for type I procollagen and fibronectin in postburn hypertrophic scar and normal dermal fibroblasts. In this article we examine the effects of these cytokines on the expression of mRNA for collagenase and its natural inhibitor, tissue inhibitor of metalloproteinase-1. Twelve different fibroblast cell strains, six from postburn hypertrophic scar and six from the normal dermis of the same patients, were established in cell culture. The results of a dose response experiment showed increases in collagenase mRNA up to 4000 U/ml of interferon-α-2b, but maximal increases in tissue inhibitor of metalloproteinase mRNA expression and maximal decrease in mRNA for type I procollagen at 2000 U/ml. For subsequent experiments cells were treated with either interferon-α-2b (2000 U/ml) or -γ (1000 U/ml) for 96 hours. Quantitative analysis showed increases in tissue inhibitor of metalloproteinase-1 and collagenase mRNA (81% and 54%, respectively) in interferon-α-2b-treated hypertrophic scar fibroblasts. Under the same experimental conditions, interferon-α-2b had similar effects on normal dermal fibroblasts; however, interferon-γ had a differential effect on the expression of mRNA for collagenase and tissue inhibitor of metalloproteinase-1. Cells treated with interferon-γ showed increases in tissue inhibitor of metalloproteinase-1 mRNA (78% in hypertrophic scar and 56% in normal dermal fibroblasts) but decreases (59% and 42%, respectively) in collagenase mRNA. These effects appear to be selective because rehybridization of blots with a complementary DNA for tissue inhibitor of metalloproteinase-2 mRNA showed no marked alteration in the abundance of this transcript. Significantly greater collagenase activity was found in conditioned medium from interferon-α-2b-treated hypertrophic scar cells compared with that from interferon-γ-treated cells. These findings suggest that interferon α-2b would have some advantages over interferon-γ for the treatment of dermal fibroproliferative disorders, such as postburn hypertrophic scar.

Notes: After severe thermal injury, hypertrophic scarring which is associated with accumulation of extracellular matrix proteins including fibronectin, frequently develops. We have recently demonstrated that interferon alfa-2b significantly reduces the level of type 1 procollagen messenger RNA expressed by both hypertrophic and normal dermal fibroblasts. In this report, we provide evidence that this cytokine also significantly decreases the expression of fibronectin messenger RNA in human hypertrophic scar and normal dermal fibroblasts. Four dermal fibroblast cell strains were established in cell culture from four human postburn hypertrophic scar tissues with the use of normal dermal fibroblasts from the same patients as controls. These cells were then treated with 2000 U/ml interferon alfa-2b in culture medium at various times. The results of Northern analysis of interferon-treated dermal fibroblasts indicate that this cytokine reduced the expression of fibronectin messenger RNA as early as 12 hours after treatment and reached its lowest level (24% relative to untreated fibroblasts) after 96 hours. When the expression of fibronectin messenger RNA was quantified by densitometry for each individual paired cell strain, a differential response to interferon treatment was found among cell strains. The level of fibronectin messenger RNA expression decreased from 17.2% to 69% in hypertrophic scar fibroblasts and 47% to 83.7% in normal fibroblasts relative to that of untreated control values. Although this decrease was less pronounced in normal fibroblasts than in hypertrophic scar fibroblasts, this reduction was significant in both interferon alfa-2b treated hypertrophic scar fibroblasts (6.39 ± 0.71 versus 2.88 ± 0.9, n = 4, p 〈 0.05) and normal cells compared with untreated controls (5.47 ± 0.89 versus 3.64 ± 0.99, n = 4, p 〈 0.05) as assessed with Student's paired t test. Rehybridization of the RNA blot prepared from interferon alfa-2b treated and untreated hypertrophic scar fibroblasts with a complementary DNA for the tissue inhibitor of metalloproteinase type 2 gelatinase inhibitor showed no significant changes in abundance of this transcript. This result suggests that this cytokine selectively suppresses the expression of fibronectin messenger RNA and that this reduction is not due to RNA loading. A dot blot analysis of total RNA extracted from these tissues was carried out to compare the expression of fibronectin messenger RNA between human hypertrophic scar tissues and normal dermis obtained from the same patients. The blot was initially hybridized with fibronectin complementary DNA and subsequently with a complementary DNA for the tissue inhibitor of metalloproteinase type 2 to correct for RNA loading. When the ratio of fibronectin to tissue inhibitor or metalloproteinase type 2 messenger RNA expression for each hypertrophic scar tissue was compared with its normal control, this ratio was fourfold higher in human hypertrophic scar tissues relative to normal controls. In contrast, the expression of this message in cultured hypertrophic scar fibroblasts was not significantly different from that in normal fibroblasts. The results of this study suggest that hypertrophic scarring developing after thermal injury is associated with an overexpression of fibronectin messenger RNA, and interferon alfa-2b may be of therapeutic value to down-regulate the expression of this transcript.

Notes: Amorphic diamond films can be grown in an ultrahigh vacuum environment free from hydrogen with a laser plasma discharge source. This technique produces films that adhere more readily to materials for which there are important applications as protective coatings. In this work adhesion and mechanical properties of amorphic diamond films have been examined. A beam bending method has been used to measure the internal stress and a relatively low value of compressive stress was found. The dependence of stress on the laser intensities at the graphite ablation target has been studied. Analyses of these films on silicon, SiO2, ZnS, and TiAl6V4 by Rutherford backscattering spectrometry show significant interfacial layers with compositions of SiC, C0.5SiO2, C2.5ZnS, and C0.62Ti0.35Al0.05V0.02, respectively. Adhesion properties on ZnS and other substrates have also been examined for harsh environments. The mechanical properties of hardness, Young's modulus, and stiffness have been obtained with a nanoindentation technique. These results together with the minimal amount of hydrogen in our process, make amorphic diamond an excellent candidate for direct deposition on several substrates including ZnS.

Notes: It has been previously reported that layers of amorphic diamond can be grown in a UHV environment free from hydrogen with a laser plasma source. Some advantages are offered by this technique which produces films that adhere more readily to materials for which there are important applications. Theory has recently suggested a structure for amorphic diamond that comprises nodules of carbon atoms linked by sp3 bonds in a matrix of other polytypes and the purpose of this article is to communicate strong evidence in support of that hypothesis. Extensive examinations of a variety of films with a scanning tunneling microscope show a clearly prevalent structure composed of dense nodules. Grain size is about 1000 A(ring) and the diamond character is attested by the agreement of morphology, high density, optical properties, soft x-ray spectroscopy, hardness, and lack of appreciable hydrogen. Measurements agree in supporting a fraction of about 75% diamond contents. The principal conclusion is that this material prepared with a laser plasma source has the structure expected for amorphic diamond.

Notes: Recent experiments have identified the microstructure of amorphic diamond with a model of packed nodules of amorphous diamond expected theoretically. However, this success has left in doubt the relationship of amorphic diamond to other noncrystalline forms of carbon. This work reports the comparative examinations of the microstructures of samples of amorphic diamond, i-C, and amorphous carbon. Four distinct morphologies were found that correlated closely with the energy densities used in preparing the different materials.

Notes: Films of amorphic diamond can be deposited from laser plasma ions without the use of catalysts such as hydrogen or fluorine. Prepared without columnar patterns of growth, the layers of this material have been reported to have "bulk'' values of mechanical properties that have suggested their usage as protective coatings for metals. Described here is a study of the bonding and properties realized in one such example, the deposition of amorphic diamond on titanium. Measurements with Rutherford backscattering spectrometry and transmission electron microscopy showed that the diamond coatings deposited from laser plasmas were chemically bonded to Ti substrates in 100–200-A(ring)-thick interfacial layers containing some crystalline precipitates of TiC. Resistance to wear was estimated with a modified sand blaster and in all cases the coating was worn away without any rupture or deterioration of the bonding layer. Such wear was greatly reduced and lifetimes of the coated samples were increased by a factor of better than 300 with only 2.7 μm of amorphic diamond.

Notes: The evolution equation governing the positions of two interacting nonpropagating solitons is found by using the variational principle approach. Furthermore, the potential which characterizes the interaction between solitons is derived, from which some important results are obtained: (1) Two solitons with the same polarity always attract each other, while those with opposite polarity repel. (2) The repulsion is much weaker than the attraction and both attraction and repulsion are of short distance. (3) The period of mutual oscillation caused by interaction between two solitons with the same polarity increases as the drive amplitude rises; especially, the period can spread from zero to infinity as the initial distance between solitons increases. All the above results are well coincident with experiments.

Notes: Background : Studies on the use of low-dose proton pump inhibitor for the maintenance therapy of gastro-oesophageal reflux disease have shown that it might be comparable with standard-dose proton pump inhibitor treatment and superior to standard-dose histamine-2 receptor antagonist therapy.Aim : To compare the impact of standard-dose histamine-2 receptor antagonist, low-dose proton pump inhibitor and standard-dose proton pump inhibitor treatment for the maintenance therapy of gastro-oesophageal reflux disease on symptom control and health care resource utilization from the perspective of a public health organization in Hong Kong.Methods : A Markov model was designed to simulate, over 12 months, the economic and clinical outcomes of gastro-oesophageal reflux disease patients treated with standard-dose histamine-2 receptor antagonist, low-dose proton pump inhibitor and standard-dose proton pump inhibitor. The transition probabilities were derived from the literature. Resource utilization was retrieved from a group of gastro-oesophageal reflux disease patients in Hong Kong. Sensitivity analysis was conducted to examine the robustness of the model.Results : The standard-dose proton pump inhibitor strategy was associated with the highest numbers of symptom-free patient-years (0.954 years) and quality-adjusted life-years gained (0.999 years), followed by low-dose proton pump inhibitor and standard-dose histamine-2 receptor antagonist. The direct medical cost per patient in the standard-dose proton pump inhibitor group (US$904) was lower than those of the low-dose proton pump inhibitor and standard-dose histamine-2 receptor antagonist groups.Conclusions : The standard-dose proton pump inhibitor strategy appears to be the most effective and least costly for the maintenance management of patients with gastro-oesophageal reflux disease in Hong Kong.