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We report ordering of polymer drops that takes place when a thin polystyrene film confined by polydimethylsiloxane walls dewets on a silicon substrate. When annealed above the glass transition temperature, the thin polymer film dewets, resulting in the formation of a regular structure inside and outside the confinement. It is found that the ordering becomes strongly suppressed as the film thickness increases and the pattern size decreases due to the physical confinement of the mold. As a result, the ordering can take place only when the wavelength of the capillary wave is smaller than the characteristic length of the physical confinement. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Aging behavior of red, green, and blue photoluminescence from porous silicon formed by electrochemical etching aided with zinc has been studied over a 3 month time span. Time-resolved photoluminescence spectra and decay dynamics have revealed that there are two radiating states in Zn-aided porous silicon. One is the quantum confinement and the other is the oxygen-related defect. For green emission, the wavelength shifts from 520 to 420 nm and its photoluminescence spectra and decay behavior become very similar to those of blue emission. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report dewetting behavior of thermally annealed thin polymer strips of poly (styrene-b-butadiene-b-styrene) and polystyrene films that are laterally confined by polydimethylsiloxane walls on silicon substrate. Regularly spaced holes are initially nucleated on the polymer surface and then grow with the aid of the confining walls, resulting in the formation of distinctly observable, regularly spaced blocks of the strip. It is observed that the dependence of hole density on the film thickness severely deviates from the conventional capillary wave model. This anomaly may be related to the viscoleastic properties of the polymer film. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study which developed a theoretical model for the composition dependence of the activation energy in solid phase epitaxial growth of Si[sub1-x]Ge[subx] alloys. Description of the proposed models for the solid phase epitaxy mechanism (SPE); Requirements for the recrystallization in SPE; Comparison between the regrowth rate of stressed and stress-relaxed alloys.

The compensation effect, well known in catalytic reactions, is shown to apply equally well to the solid-phase epitaxial (SPE) growth of Si[sub 1-x]Ge[sub x] alloys. A linear relationship exists between the logarithm of the pre-exponential factor and the activation energy of the SPE growth rate. This linear relationship, together with the activation energy obtained earlier, enables one to completely describe the growth rate of Si[sub 1-x]Ge[sub x] alloys. The effect holds for both strained and unstrained SPE. The model is applicable to other binary alloys. © 1997 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In-vessel retention (IVR) of core melt is a key severe-accident-management strategy adopted by some operating nuclear power plants and proposed for some advanced light water reactors (LWRs). If there were inadequate cooling during a reactor accident, a significant amount of core material could become molten and relocate to the lower head of the reactor vessel, as happened in the Three Mile Island Unit 2 accident. If it is possible to ensure that the vessel head remains intact so that relocated core materials are retained within the vessel, the enhanced safety associated with these plants can reduce concerns about containment failure and associated risk. For example, the enhanced safety of the advanced 600 MW(electric) pressurized water reactor (AP600) designed by Westinghouse, which relied upon external re-actor vessel cooling (ERVC) for IVR, resulted in the U.S. Nuclear Regulatory Commission approving the design without requiring that certain features common to existing LWRs, such as containment sprays, be safety related. Clearly, ERVC offers the potential to reduce the AP6OO's construction and operating costs. However, it is not clear that the ERVC proposed for the AP600 could provide sufficient heat removal for higher-power reactors [up to 1500 MW(electric)] without additional enhancements. This paper reviews efforts made and results reported regarding the enhancement of IVR in LWRs. Where appropriate, the paper identifies what additional data or analyses are needed to demonstrate that there is sufficient margin for successful IVR in high-power thermal reactors. [ABSTRACT FROM AUTHOR]

The surface topography of a real lotus leaf was successfully replicated using a capillarity directed soft lithographic technique. The replication was carried out on poly(methyl methacrylate) (PMMA) film coated on a silicon wafer. The friction property of the patterned surfaces was investigated on a microscale. Its friction coefficient was almost six times lower than that of the PMMA thin film. The reduced real area of contact projected by the patterned surface appears to be the main reason for its superior friction property. [ABSTRACT FROM AUTHOR]

Detailed analyses of a late-phase melt progression in the advanced power reactor (APR)1400 were completed to identify the melt and the thermal-hydraulic states of the in-vessel materials in the reactor vessel lower plenum at the time of reactor vessel failure to evaluate the candidate strategies for an in-vessel corium retention (IVR). Initiating events considered included high-pressure transients of a total loss of feed water (LOFW) and a station blackout (SBO) and low-pressure transients of a 0.0009-m² small, 0.0093-m² medium, and 0.0465-m² large-break loss-of-coolant accident (LOCA) without safety injection. Best-estimate simulations for these low-probability events with conservative accident progression assumptions that lead to reactor vessel failure were performed by using the SCDAP/RELAP5/MOD3.3 computer code. The SCDAP/RELAP5/MOD3.3 results have shown that the pressurizer surge line failed before the reactor vessel failure, which results in a rapid decrease of the in-vessel pressure and a delay of the reactor vessel failure time of ∼40 rain in the high-pressure sequences of the total LOFW and the SBO transients. In all the sequences, ∼80 to 90% of the core material was melted and relocated to the lower plenum of the reactor vessel at the time of reactor vessel failure. The maximum value of the volumetric heat source in the corium pool was estimated as 1.9 to 3.7 MW/m³. The corium temperature was ∼2800 to 3400 K at the time of reactor vessel failure. The highest volumetric heat source sequence is predicted for the 0.0465-m² large-break LOCA without safety injection in the APR1400, because this sequence leads to an early reactor vessel failure. [ABSTRACT FROM AUTHOR]

In-vessel retention (IVR) of core melt that may relocate to the lower head of a reactor vessel is a key severe accident management strategy adopted by some operating nuclear power plants and proposed for several advanced light water reactors. A U.S.-Korean International Nuclear Energy Research Initiative project has been initiated to explore design enhancements that could increase the margin for IVR for advanced reactors with higher power levels [up to 1500 MW(electric)]. As part of this effort, an enhanced in-vessel core catcher is being designed and evaluated. To reduce cost and simplify manufacture and installation, this new core catcher design consists of several interlocking sections that are machined to fit together when inserted into the lower head. If needed, the core catcher can be manufactured with holes to accommodate lower head penetrations. Each section of the core catcher consists of two material layers with an option to add a third layer (if deemed necessary). The first is a base material that has the capability to support and contain the mass of core materials that may relocate during a severe accident; the second is an oxide coating on top of the base material, which resists interactions with high-temperature core materials; and the third is an optional coating on the bottom side of the base material to protect it from oxidation during the lifetime of the reactor. This paper summarizes results from the in-vessel core catcher design and evaluation efforts, focusing on recently obtained results from materials interaction tests and prototypic testing activities. [ABSTRACT FROM AUTHOR]

We have developed soft molding as a method for meso-scale-area fabrication of three-dimensional structures. The soft molding, which is a form of soft lithography, involves placing an elastomeric mold on the surface of a spin-coated polymer film with a slight pressure (<1 N/cm[sup 2]), allowing the mold to absorb solvent, releasing the pressure, and then letting the mold and the substrate remain undisturbed for a period of time. The three-dimensional structure thus formed is robust in that the pattern fidelity is preserved without any distortion or defects. For the soft molding to be successful, the rate of solvent absorption by the mold should be larger than the rate of solvent evaporation. The method is demonstrated with several three-dimensional structures. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present the effect of nanotopographically defined surfaces on adipocyte differentiation using various nanogroove patterns. Parallel nanogroove arrays with equal inter-groove distance (400, 550, 800 nm width) and varying distances (550 nm width with three different spacings of 550, 1100, and 2750 nm) were fabricated by UV-assisted capillary force lithography (CFL) on 18 mm diameter glass coverslips using biocompatible polyurethane (PU)-based material. After coating with fibronectin and subsequent culture of 3T3-L1 preadipocytes, the degree of adipocyte differentiation was determined by Oil Red O staining and adipogenic gene expression. We observed that adipocyte differentiation was slightly but substantially affected by culture on various nanogrooved surfaces. In particular, the cell crawling into nanogrooves contributed substantially to an enhanced level of differentiation with higher contact guidance, suggesting that cell-to-surface interactions would play a role for the adipocyte differentiation.

We present a simple solvent-assisted capillary molding method to fabricate zinc oxide (ZnO) nanostructures using an ultraviolet (UV) curable polyurethane acrylate (PUA) mold. A thin film of the ZnO sol-gel precursor solution in methyl alcohol was prepared by spin coating on a solid substrate and subsequently a nanopatterned PUA mold was brought into conformal contact with the substrate under slight physical pressure (∼3.5 bar). After annealing at 230 °C for 4 h, well-defined ZnO nanostructures formed with feature size down to ∼50 nm, aided by capillary rise and solvent evaporation. It was found that the height of capillary rise depended highly on the applied pressure. A simple experimental setup was devised to examine the effects of pressure, revealing that the optimum pressure ranged from 3.5 bar to 5 bar. Also, ZnO nanorods could be selectively grown on patterned regions using the seed layer as a pseudocatalyst when the width of the seed layer was larger than ∼200 nm.

A simple, one-step method is developed to fabricate various nanostructures such as nanoholes and nanolines based on the detachment of an organic polymer film in contact with a patterned polyurethane acrylate mould under a low physical pressure (1-2 bar) at ambient conditions. Calculation of the work of adhesion based on contact angle measurements indicates that the adhesion strength at the organic/mould interface is greater than that at the organic/substrate interface, resulting in a successful detachment without any surface modifications. 4,4(')-bis[N-1-napthyl-N-phenyl-amino]biphenyl (NPB) is used as the organic film owing to its low cohesion energy and stability in air. Nanoholes as small as 150 nm and nanolines as small as 50 nm have been fabricated using this approach. These nanostructures are used as a template for selective deposition of silver nanoparticles and a wet/dry etch resist for further pattern transfer.

A simple method was developed to fabricate polyethylene glycol (PEG) nanostructures using capillary lithography mediated by ultraviolet (UV) exposure. Acrylate-containing PEG monomers, such as PEG dimethacrylate (PEG-DMA, MW = 330), were photo-cross-linked under UV exposure to generate patterned structures. In comparison to unpatterned PEG films, hydrophobicity of PEG nanostructure modified surfaces was significantly enhanced. This could be attributed to trapped air in the nanostructures as supported by water contact angle measurements. Proteins (fibronectin, immunoglobulin, and albumin) and cells (fibroblasts and P19 EC cells) were examined on the modified surfaces to test for the level of protein adsorption and cell adhesion. It was found that proteins and cells preferred to adhere on nanostructured PEG surfaces in comparison to unpatterned PEG films; however, this level of adhesion was significantly lower than that of glass controls. These results suggest that capillary lithography can be used to fabricate PEG nanostructures capable of modifying protein and cell adhesive properties of surfaces.

We present a general criterion for determining the dynamic instability of a thin polymer film that is strongly confined to a substrate. When such a polymer film is heated above its glass transition temperature, it dewets from the substrate by a spinodal dewetting scenario, in which the onset of the instability is governed by dispersion force and residual thermal stress. It turns out that the thermal stress plays an important role when there is a special interaction between a polymer and a substrate.

RNA, extracted from peripheral blood mononuclear cells (PBMC) obtained from 81 Korean psychiatric patients (39 with schizophrenia, 33 with bipolar affective disorders and nine with major depression), was analyzed for a 391-nucleotide, highly conserved region of the p24 protein-encoding ORF II of Borna disease virus (BDV), using nested reverse transcription-polymerase chain reaction (RT-PCR). BDV genomic RNA was not detected in PBMC from any of the 81 Korean psychiatric patients. These data do not support an etiologic association between BDV infection and neuropsychiatric disorders in humans.

The effect of dexamethasone (DEX) on the activation of the inducible form of nitric oxide synthase (iNOS) and its relation to the formation of oxidation products of nitric oxide (NO2-+ NO3-, NOx) in infarcted heart muscle of rabbits was investigated. Myocardial infarction was produced by ligation of the first anterior branch of the left circumflex coronary artery. NOx was determined by chemiluminescence and iNOS by conversion of L-[14C]-arginine to L-[14C]-citrulline. The rise in myocardial iNOS production, which followed onset of myocardial ischemia, was suppressed by DEX. In addition, following coronary artery ligation, coronary arterial venous differences of NOx increased markedly; this effect was also partially abolished by DEX. Cardiac origin of NOx was confirmed by the linear relationship between coronary A-V NOx difference and myocardial formation of iNOS. This relationship was preserved after administration of DEX. Therefore glucocorticoids interfere with the myocardial NO production and thus diminish the concentration of its oxidative products in plasma.

The effect of Acetylsalicylic Acid (ASA, Aspirin) on the myocardial production of the inducible form of nitric oxide synthase (iNOS) and the oxidation products of nitric oxide (nitrite, NO-2 and nitrate, NO-3: NOx) were studied in the rabbit heart two days after ligation of a branch of the left circumflex coronary artery. ASA was administered intravenously as AspisolR, DL-Lysinmono(acetylsalicylate) which is soluble in water. Animals received a total dose of 250, 375, or 500 mg/kg of ASA in five divided doses intravenously. Significant inhibition of iNOS was noted in the infarcted portion of the myocardium at 375 and 500 mg/kg of ASA. The reduction in myocardial nitric oxide (NO) production was paralleled by a diminution in coronary arterial-venous difference of NOx, demonstrating that ASA inhibition extended also to the oxidation products of NO. ASA is an inhibitor of cyclooxygenase (COX). The inhibition of iNOS by ASA demonstrates the close relationship between COX and iNOS activity in the heart in situ. Whether activity of the infarcted heart is influenced by the diminution in the production of NO by ASA is not known., (Copyright 1998 Academic Press.)

We conducted a placebo-controlled, randomized, double-blind, 8-week trial of sertraline added to haloperidol treatment in patients with schizophrenia to evaluate changes in clinical measures and pharmacokinetic interactions with haloperidol. In addition to their haloperidol regimen, 36 inpatients with chronic schizophrenia were randomly assigned to receive capsulized sertraline (50 mg/day; N = 18) or identically capsulized placebo (N = 18) for 8 weeks. The results from the Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression (CGI) Scale, Simpson-Angus Extrapyramidal Effects (S-A) Scale, and plasma concentration levels of haloperidol and reduced haloperidol were examined at baseline and 2, 4, 6, and 8 weeks of treatment. No significant differences between the three PANSS factors (positive, negative, general psychopathology) scores, CGI Scale scores, or S-A Scale scores were recorded at any point during sertraline and placebo treatment. Neither plasma haloperidol or reduced haloperidol concentrations was changed significantly at any point during the sertraline and placebo treatments. In this study, the addition of sertraline 50 mg to the treatment regimen of inpatients did not differ significantly from the placebo effect on positive and negative symptoms and extrapyramidal side effects. The results further indicate that the pharmacokinetics of haloperidol are seemingly unaffected by sertraline.

Objectives: We sought to assess whether oxidation products of nitric oxide (NO), nitrite (NO2-) and nitrate (NO3-), referred to as NOx, are released by the heart of patients after acute myocardial infarction (AMI) and whether NOx can be determined in peripheral blood of these patients., Background: Previously we reported that in experimental myocardial infarction (rabbits) NOx is released mainly by inflammatory cells (macrophages) in the myocardium 3 days after onset of ischemia. NOx is formed in heart muscle from NO; NO originates through the activity of the inducible form of nitric oxide synthase (iNOS)., Methods: Eight patients with acute anterior MI and an equal number of controls were studied. Coronary venous blood was obtained by coronary sinus catheterization; NOx concentrations in coronary sinus, in arterial and peripheral venous plasma were measured. Left ventricular end-diastolic pressure was determined. Measurements were carried out 24, 48 and 72 h after onset of symptoms. The type and location of coronary arterial lesions were determined by coronary angiography. Plasma NO3- was reduced to NO2- by nitrate reductase before determination of NO2- concentration by chemiluminescence., Results: The results provided evidence that in patients with acute anterior MI, the myocardial production of nitrite and nitrate (NOx) was increased, as well as the coronary arterial-venous difference. Increased NOx production by the infarcted heart accounted for the increase of NOx concentration in arterial and the peripheral venous plasma. The peak elevation of NOx occurred on days 2 and 3 after onset of the symptoms, suggesting that NOx production was at least in part the result of production of NO by inflammatory cells (macrophages) in the heart., Conclusions: The appearance of oxidative products of NO (NO2- and NO3-) in peripheral blood of patients with acute MI is the result of their increased release from infarcted heart during the inflammatory phase of myocardial ischemia. Further studies are needed to define the clinical value of these observations.

Background: It has been postulated that autoimmune process may play a role in the pathogenesis of symptoms in some schizophrenic patients. Findings of altered interleukin (IL) regulation have been regarded as additional proof that schizophrenia has an autoimmunological background., Methods: Sixteen patients who fulfilled DSM-IV criteria for schizophrenia and who were drug free for at least six months and the same number of age- and sex-matched controls were recruited. The severity of symptoms in schizophrenia was assessed by BPRS. Phytohemagglutinin (PHA)-stimulated production and serum level of IL-1 beta, IL-2, and IL-6 were measured by enzyme-linked immunosorbent assay (ELISA)., Results: There was a significant decrease of IL-2 production (p < .01) in schizophrenic patients and a significant increase of IL-2 serum level (p < .01). No significant difference of IL-1 beta and IL-6 was found. Some patients and controls had measurable serum level of IL-1 beta and IL-6. No significant correlation between production and serum level of IL-1 beta, -2, -6 and age, duration of illness, and BPRS score in schizophrenics was found., Conclusions: This is the first study to describe a decrease of IL-2 production and increase of IL-2 serum level in non-Caucasian schizophrenic patients. These findings are further evidence that autoimmune process is present, regardless of ethnic origin, in some schizophrenic patients.

The neurotrophins are a class of signaling molecules known for their growth and survival-promoting activities during neuronal development. Recent studies suggest that the neurotrophins, including brain-derived neurotrophic factor (BDNF), can also dramatically influence synaptic transmission in the adult hippocampus. The experiments described in this paper indicate that ability of BDNF to potentiate synaptic transmission in the hippocampus relies on functional Trk B receptors. Moreover, the rate at which BDNF is applied to hippocampal synapses is also a potent determinant of whether synaptic potentiation will result. Hippocampal slices perfused with BDNF at a very slow flow rate (e.g., < or = 25 ml/hr) did not show synaptic potentiation. Increasing the rate of BDNF application resulted in synaptic potentiation in which the magnitude and onset kinetics of the potentiation were determined by the rate of BDNF delivery. Immunocytochemical analysis of BDNF detected with confocal microscopy confirmed these electrophysiological observations, indicating that the penetration of BDNF into hippocampal slices is influenced dramatically by the perfusion rate.