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Electrical, thermal and mechanical properties of conductive polymer composites were investigated in the present work. The composites were polyamide-6 (PA6)/stainless steel fibre (SSF) (PA6 matrix filled by SSFs) and PA6/SSF/CNT (PA6 matrix filled by SSFs and carbon nanotubes) systems. The distribution of fillers in the composites was observed by scanning electron microscopy. The relation between the resistivity of the composites and the mass fraction of fillers was determined, and the conductive percolation threshold value was approximately evaluated according to the sudden dropping of the resistivity. Thermal and mechanical properties of the composites were investigated by means of dynamic mechanical analysis, thermogravimetric analysis and differential scanning calorimeter analysis.

This paper reports a theoretical and experimental study for thermal transport in a thin slice of human tooth induced by a 120 fs, 800 nm pulse laser at a repetition rate of 1 kHz. The surface reflectivity of enamel and the convection heat transfer coefficient were determined using an inverse heat transfer analysis. Instead of a fully three-dimensional modeling, two simplified two-dimensional (2D) planar and axisymmetric heat conduction models were proposed to simulate the temperature fields. The temperature responses obtained from the 2D planar and axisymmetric model agree well with the experimental measurements. On the other hand, the one-dimensional (1D) result significantly differs from the 2D axisymmetric one, suggesting that care should be taken when a 1D thermal model is considered for estimating temperature response.

This study presents the findings from a scoping review of recent, original research investigating changes in brain structure andor function following pediatric concussion or mild traumatic brain injury (mTBI) using MRI and functional MRI techniques.

ABSTRACTThe temporal/spatial evolution processes of the flow pattern, velocity distribution, and wall shear stress of pulsatile water flows in the arch of 180o turn-around tubes with/without stenosis were experimentally studied by using the particle image velocimetry (PIV). Three transparent tubes made of glass were used: A tube without stenosis in the arch, a tube with a 25% stenosis at the inner wall of arch, and a tube with a 50% stenosis at the inner wall of arch. Here the percentage of stensis denoted the ratio between the stenosis height to inner diameter of arch in the diametral cross section across mid-arch of the central plane. The flow was provided by a pump which approximately simulated the pulsatile pressure waves of human heart beats. The systole to diastole time period ratio is set at 35%:65%. The Womersley parameter, Dean number, and time-averaged Reynolds number were 14, 2348, and 3500, respectively. In the arch of the turn-around tube without stenosis, no boundary layer separation was found during the systolic phase. The reverse flow and recirculation bubble appeared in the arch only during the diastolic phase. The inner wall of the arch experienced lower wall shear stress during the diastolic phase due to the formation of recirculation bubble and secondary flow. In the arch with stenosis, the boundary layer separated from the inner wall and formed a recirculation bubble downstream the stenosis during the systolic phase. Lower stenosis (25%) did not cause drastic variation of the wall shear stresses. At higher stenosis (50%), however, the wall shear stress around the inner wall downstream the stenosis became extraordinarily low, whereas the wall shear stress around the upstream region of the outer wall of the downstream branch of the tube became anomalously large.

Zwitter polymers are defined as polymers that undergo transformation from a linear to a crosslinked structure under electron‐beam irradiation. A resist polymer may be either linear or crosslinked, depending on electron‐beam dosage. The structural transformation of acrylic resin make it suitable for applications in positive and negative resists in the semiconductor field. The contrast ratio and threshold dose both increase with increasing resist thickness for both the positive and negative resists, while the positive resist exhibits better contrast than the negative. The intensity of the characteristic Fourier‐transform infrared absorption band at 1612 cm–1(vinyl group) is used to explain the phenomena behind these resist transformations. We evaluate the effects of two important processing conditions: the soft baking and post‐exposure baking temperatures. Pattern resolution decreases upon increasing the baking temperature, except for soft baking of the negative resist. The effect of electron dose on the pattern resolution is also discussed in detail for both resists. High electron‐beam exposure does not improve the etching resistance of the resist because of the porous nature of the resist that develops after high‐dosage irradiation.

Vigorous exercise transiently increases the risk of primary cardiac arrest. The reciprocal modulation of platelet and polymorphonuclear leukocyte (PMN) activities is important in the pathogenesis of thrombosis. This study investigates how strenuous, acute exercise affects platelet–PMN reciprocal modulation by closely examining 18 sedentary men who exercised strenuously on a bicycle ergometer. Shear-induced platelet activation, PMN interaction with surface-adherent platelets under shear flow, and PMN-dependent inhibition of platelet activation were measured both before and immediately after exercise. Analytical results can be summarized as follows: (i) shear-induced platelet adhesion on fibronectin-coated surface as well as ADP-induced release of platelet soluble P-selectin release and elevation of [Ca2+]isignificantly increases after strenuous exercise; (ii) strenuous exercise is associated with higher velocity and percentage of rolling PMNs and lower numbers of PMNs remaining bound to surface-adherent platelets under shear flow than at rest; (iii) PMN-dependent inhibition of platelet [Ca2+]ielevation and soluble P-selectin release after strenuous exercise is much greater than that at rest; and (iv) strenuous exercise increases PMN-derived nitric oxide metabolite level and reduces oxidized low-density lipoprotein-promoted interaction between platelets and PMNs. Therefore, we conclude that platelet activity may be sensitized by strenuous exercise. However, strenuous exercise can also simultaneously enhance the antiplatelet effect of PMNs. The finding provides a new insight into the negative feedback of PMNs against exercise-evoked platelet-related thrombotic risk.

AbstractPurpose: To study the expression of TIMP-4 in cultured corneal cells and in corneal neovascularization. Methods: Human limbo-corneal epithelial cells, fibroblasts, and endothelial cells were cultured in serum-free, PMA- or basic fibroblast growth factor (bFGF)-treated condition. Neovascularization in rat cornea was induced by suturing. The expression of TIMP-4 was examined by immunohistochemistry, Western blot and RT-PCR. Results: TIMP-4 was constitutively expressed in cultured human corneal cells. The expression was only mildly enhanced after mitogen treatment. TIMP-4 immunoreactivity was predominantly expressed in normal rat corneal epithelium, and also in ingrowing blood vessels following suturing, which persisted up to day 28. Increased staining in corneal epithelium and blood vessels were also noted in vascularized human corneas. Conclusions: TIMP-4 is expressed in the cornea, which may play a role in modulating extracellular matrix remodeling associated with corneal wound healing and angiogenesis.

Caveolae are vesicular invaginations of the plasma membranes that regulate signal transduction and transcytosis, as well as cellular cholesterol homeostasis. Our previous studies indicated that the removal of cholesterol from aortic endothelial cells and smooth muscle cells in the presence of HDL is associated with plasmalemmal invaginations and plasmalemmal vesicles. The goal of the present study was to investigate the location and distribution of caveolin-1, the main structural protein component of caveolae, in cholesterol-loaded aortic endothelial cells after HDL incubation. Confocal microscopic analysis demonstrated that the caveolin-1 appeared to colocalize with HDL-fluorescein 1,1'-dioctadecyl 3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) conjugates on the cell surface. No free HDL-DiI conjugates were revealed in the cytoplasm. Immunoelectron microscopy further demonstrated that caveolin-1 gold (15 nm) conjugates colocalized with HDL gold (10 nm) conjugates in the plasmalemmal invaginations. These morphological results indicated that caveolae are the major membrane domains facilitating the transport of excess cholesterol to HDL on the cell surface of aortic endothelial cells.

The nature of phase transformations and phase equilibria in the Ti- V - N system with about 20 at.-%V and 11 -15 at.-%N has been studied at 1200°C. The results obtained for the titanium rich corner of the Ti - V- N phase diagram provide new information on phase coexistence and the composition of particular phases in this system. Thermodynamic calculations, based on the use of thermodynamic parameters from the three binary subsystems, together with newly assessed thermodynamic parameters published previously, were carried out. Reasonable agreement was obtained between the experiment and the calculations.

Abstract:  An incremental approach is presented to model transient, elastoplastic dynamic problems using the corrective smoothed particle method. It uses the corrective first- and second-derivative approximations to solve the nonlinear momentum equations, which is described in terms of displacement increments entirely. This algorithm not only satisfies the nodal completeness condition but also exhibits no integrablity problem. Several 2D examples, including forced vibration, stress wave propagation, and rigid wall impact, are investigated to demonstrate the numerical stability and accuracy of the proposed method.

Glass beads, non‐modified and modified separately with two different coupling agents, were incorporated in high density polyethylene to prepare composite materials with different interfacial adhesion strengths. Tensile tests show that the mechanical behaviour of the materials is sensitive to the strain rates. The strong interfacial adhesion can delay the occurrence of damage and so increase the load‐bearing ability under both monotonic and cyclic loading. In situ tensile tests give damage mechanisms mainly induced by the interfacial debonding. The stronger the interfacial adhesion, the lower the number of glass beads debonded from the matrix under a given stress. The degree of microdamage defined as the percentage of debonded particles is obtained as a function of the applied load.© 2001 Society of Chemical Industry

We have previously reported that 14,15-epoxyeicosatrienoic acid (14, 15-EET) is a potent mitogen for the renal epithelial cell line, LLCPKcl4. This mitogenic effect is dependent upon activation of a protein-tyrosine kinase cascade that results in activation of mitogen-activated protein kinase and phosphatidylinositol 3-kinase. Because of suggestive evidence that 14,15-EET also activated Src in these cells, we stably transfected LLCPKcl4 with an expression construct of the C-terminal Src kinase (CSK), which inhibits Src family kinase activity. In vitro Src kinase activity assays confirmed that in empty vector-transfected cells (Vector cells), 14, 15-EET increased Src kinase activity, while in clones overexpressing CSK mRNA and immunoreactive protein (CSK cells), 14,15-EET-induced activation of Src was almost completely blocked (94% inhibition). Of interest, epidermal growth factor (EGF) and fetal bovine serum (FBS) also increased Src activity in Vector cells, but not in CSK cells, further confirming the ability of CSK overexpression to prevent Src activation. CSK cells failed to increase [(3)H]thymidine incorporation in response to exogenous 14,15-EET. In contrast, both EGF and FBS significantly increased [(3)H]thymidine incorporation in CSK cells. Immunoprecipitation with anti-phosphotyrosine antibodies and immunoblotting with an antibody against extracellular signal-regulated kinase (ERK) indicated that in CSK cells, 14,15-EET failed to activate ERK1 and ERK2; however, EGF- and FBS-induced activation of ERKs was not different from that seen in Vector cells. In Vector cells, the 14,15-EET-stimulated tyrosine phosphorylation of ERKs was blocked by pretreatment with 1 microm PP2, a selective inhibitor of Src kinases. The present study demonstrates that 14, 15-EET exerts its mitogenic effects predominantly through a Src kinase-mediated pathway, which is the most upstream signaling step determined to date in the 14,15-EET-activated tyrosine kinase cascade in renal epithelial cells.

AbstractGrowth factor receptors activate tyrosine kinases and undergo endocytosis. Recent data suggest that tyrosine kinase inhibition can affect growth factor receptor internalization. The type 1 angiotensin II receptor (AT1R) which is a G-protein-coupled receptor, also activates tyrosine kinases and undergoes endocytosis. Thus, we examined whether tyrosine kinase inhibition affected AT1R internalization. To verify protein tyrosine phosphorylation, both LLCPKCI4 cells expressing rabbit AT1R (LLCPKAT1R) and cultured rat mesangial cells (MSC) were treated with angiotensin II (Ang II) [1–100 nM] then solubilized and immunoprecipitated with antiphosphotyrosine antisera. Immunoblots of these samples demonstrated that Ang II stimulated protein tyrosine phosphorylation in both cell types. Losartan [1 M], an AT1R antagonist, inhibited Ang II-stimulated protein tyrosine phosphorylation. LLCPKAT1Rcells displayed specific 125I-Ang II binding at apical (AP) and basolateral (BL) membranes, and both AP and BL AT1R activated tyrosine phosphorylation. LLCPKAT1Rcells, incubated with genistein (Gen) [200 M] or tyrphostin B-48 (TB-48) [50 M], were assayed for acid-resistant specific 125I-Ang II binding, a measure of Ang II internalization. Both Gen (n=7) and TB-48 (n=3) inhibited AP 125I-Ang II internalization (80 ± 7 inhibition; p < 0.025 vs. control). Neither compound affected BL internalization. TB-1, a non-tyrosine kinase-inhibiting tyrphostin, did not affect AP 125I-Ang II endocytosis (n=3), suggesting that the TB-48 effect was specific for tyrosine kinase inhibition. Incubating MSC with Gen (n=5) or herbimycin A [150 ng/ml] (n=4) also inhibited MSC 125I-Ang II internalization (82 ± 11 inhibition; p < 0.005 vs. control). Thus, tyrosine kinase inhibition prevented Ang II internalization in MSC and selectively decreased AP Ang II internalization in LLCPKAT1Rcells suggesting that AP AT1R in LLCPKAT1Rcells and MSC AT1R have similar endocytic phenotypes, and tyrosine kinase activity may play a role in AT1R internalization.

A common feature of most isolated cell systems is low or undetectable levels of bioactive cytochrome P450. We therefore developed stable transfectants of the renal epithelial cell line, LLCPKcl4, that expressed an active regio- and enantioselective arachidonic acid (AA) epoxygenase. Site-specific mutagenesis was used to convert bacterial P450 BM-3 into an active regio- and stereoselective 14S,15R-epoxygenase (F87V BM-3). In clones expressing F87V BM-3 (F87V BM-3 cells), exogenous AA induced significant 14S,15R-epoxyeicosatrienoic acid (EET) production (241. 82 ng/10(8) cells, >97% of total EETs), whereas no detectable EETs were seen in cells transfected with vector alone. In F87V BM-3 cells, AA stimulated [3H]thymidine incorporation and increased cell proliferation, which was blocked by the tyrosine kinase inhibitor, genistein, by the phosphatidylinositol 3 (PI-3) kinase inhibitors, wortmannin and LY294002, and by the mitogen-activated protein kinase kinase inhibitor, PD98059. AA also induced tyrosine phosphorylation of extracellular signal-regulated kinase (ERK) and PI-3 kinase that was inhibited by the cytochrome P450 BM-3 inhibitor, 17-ODYA. Epidermal growth factor (EGF) increased EET production in F87V BM-3 cells, which was completely abolished by pretreatment with either 17-ODYA or the phospholipase A2 (PLA2) inhibitor, quinacrine. Compared with vector-transfected cells, F87 BM-3 transfected cells demonstrated marked increases in both the extent and sensitivity of DNA synthesis in response to EGF. These changes occurred in the absence of significant differences in EGF receptor expression. As seen with exogenous AA, EGF increased ERK tyrosine phosphorylation to a significantly greater extent in F87V BM-3 cells than in vector-transfected cells. Furthermore, in these control cells, neither 17-ODYA nor quinacrine inhibited EGF-induced ERK tyrosine phosphorylation. On the other hand, in F87V BM-3 cells, both inhibitors reduced ERK tyrosine phosphorylation to levels indistinguishable from that seen in cells transfected with vector alone. These studies provide the first unequivocal evidence for a role for the AA epoxygenase pathway and endogenous EET synthesis in EGF-mediated signaling and mitogenesis and provide compelling evidence for the PLA2-AA-EET pathway as an important intracellular-signaling pathway in cells expressing high levels of cytochrome P450 epoxygenase.

Abstract:  Two different solution algorithms of the corrective smoothed particle method (CSPM) are developed and examined with linear elastodynamic problems. One is to use the corrective first derivative approximations to solve the stress-based momentum equations, with stresses evaluated from the strains. This is an approach that has widely been adopted in smoothed particle hydrodynamics (SPH) methods. The other is new, in which the corrective second derivative approximations are used to directly solve the displacement-based Navier equations. The former satisfies the nodal completeness condition but lacks integrability; on the contrary, the latter is truly complete. Numerical tests show that the latter outperforms the former as well as other existing SPH methods, as expected.

Combining the kernel estimate with the Taylor series expansion is proposed to develop a Corrective Smoothed Particle Method (CSPM). This algorithm resolves the general problem of particle deficiency at boundaries, which is a shortcoming in Standard Smoothed Particle Hydrodynamics (SSPH). In addition, the method’s ability to model derivatives of any order could make it applicable for any time-dependent boundary value problems. An example of the applications studied in this paper is unsteady heat conduction, which is governed by second-order derivatives. Numerical results demonstrate that besides the capability of directly imposing boundary conditions, the present method enhances the solution accuracy not only near or on the boundary but also inside the domain. Published in 1999 by John Wiley & Sons, Ltd. This article is a U.S. government work and is in the public domain in the United States.

Based on the assumption that uniform dilatation has negligible effect on the yield point, a high-order yield function of non-equal stress exponents in conjunction with a non-associated flow rule is proposed to formulate 3-D plastic constitutive equations for fibrous metal matrix composites (MMC). The involved nine plastic parameters, six for the yield criterion and three for the plastic potential, can be easily calibrated with the macro stress-strain data of simple tension, pure shear, and bi-axial tension tests. It is demonstrated numerically that this theory describes anisotropic plasticity of boron-aluminum (B/Al) composites very well. It is also shown that the uniform dilatation assumption is adequate for other fiber composites. By properly selecting the plastic parameters, the present model can reduce to the nine-parameter quadratic yield function developed for graphite fiber/organic matrix composites [1], Hill's quadratic yield model [2], and von Mises and Tresca isotropic yield criteria.

In this two centre study, the efficacy of 200 mg mifepristone orally followed 48 h later by 0.4 mg misoprostol orally for menstrual regulation was investigated. The dose of mifepristone was taken the day before the expected day of menstruation. Each volunteer was planned to participate for up to 6 months. A plasma beta human chorionic gonadotrophin (HCG) was measured on the day of mifepristone intake. The study was disrupted prematurely due to low efficacy. In 125 treatment cycles the overall pregnancy rate was 17.6% (22 pregnancies) and the rate of continuing pregnancies (failure) was 4.0%. Eight women discontinued the study due to bleeding irregularities which were seen in 15 cycles (12%). These effects on bleeding pattern made the timing of treatment day difficult. Late luteal phase treatment with a combination of mifepristone and misoprostol is not adequately effective for menstrual regulation.

Abstract: A corrective Smoothed-Particle Method (CSPM) is proposed to address the tensile instability and, boundary deficiency problems that have hampered full exploitation of standard smoothed particle hydrodynamics (SPH). The results from applying this algorithm to the 1-D bar and 2-D plane stress problems are promising. In addition to the advantage of being a gridless Lagrangian approach, improving the above two major obstacles in standard SPH makes it attractive for applications in computational mechanics.

A simple, 3-D yield function that is quadratic in stresses was proposed to describe the plastic behavior of fiber composites. It relaxes the two usually used assumptions that hydrostatic stress does not influence plastic deformation and that the total plastic dilatation is incompressible. It is also general in nature to allow for composites with various fiber volume fractions and different fiber arrays. The applicability of this quadratic yield function to fiber composites was examined, and the accuracy of the elasto-plasticity model was verified by using the macro stress-strain data generated by a 3-D nonlinear micromechanics model. Because this anisotropic plasticity model is simple and is in the general form of those widely used in existing numerical plasticity codes, it can easily be incorporated into the existing codes with little effort.

We report the observation of coherent uv emission at 330.2±0.5 nm when sodium vapor in a heatpipe is irradiated with a pulsed visible dye laser with output wavelength in the 570–595 nm region. It is found that intense uv emission can be produced from Na atoms as well as from Na2 molecules. The excitation functions and their dependence on vapor density and laser power density are presented and the mechanisms for producing the emission are discussed.

Causes are investigated for the changes in precipitate crystal structure (fcc to 9R) and in morphology (degenerate plate to plate), which are observed to take place in Cr-Ni alloys as the reaction temperature decreases. Transmission electron microscopy (TEM) study is performed to determine the matrix/precipitate orientation relationship, habit plane, and growth ledge spacing. O-lattice modeling is used to show that it is likely that the metastable 9R phase forms as a transition phase at lower reaction temperatures because lattice matching at the bcc/9R habit plane is better than the matching at the bcc/fcc habit plane. The ability of the phenomenological theory of martensite crystallography (PTMC) to predict the habit plane of 9R plates precipitated by a diffusional mechanism is explained by the small lattice invariant deformation required to produce an invariant plane in Cr-Ni. Under this circumstance, the PTMC habit plane nearly coincides with the best-matching interface that presumably appears and is predicted by O-lattice theory.

A description is given of the design and operation of a new infrared spectroscopy sampling technique that permits real-time, Simultaneous MAss and Temperature CHange (SMATCH)/FT-IR measurements to be made on samples heated at high rates (up to 320°C/s) to about 600°C. The technique is illustrated with 13.4%N nitrocellulose.

The existence of two components of human leukocyte interferon has been recently reported. In the present study, the nature of this molecular heterogeneity was explored by affinity chromatography on immobilized micro- and macroligands, ion-exchange chromatography, and molecular sieving. Chromatography on a series of alkyl-agarose adsorbents shows, for the first time, the intrinsic hydrophobicity of human leukocyte interferon. Additionally, the separation of two interferon components is achieved by use of the alkyl-agarose as well as by the omega-aminoalkyl-agarose adsorbents. Clear-cut separation of the two components was also achieved by chromatography on BSA-CH-Sepharose and on DEAE-Bio Gel A. An important feature of these separations is that they do not require the use of denaturing conditions. The molecular weights of the leukocyte interferon components, as determined on Sephadex G-75, are quite similar or identical, approximately 26,000. Thus, the molecular heterogeneity of human leukocyte interferon can be attributed, at least in part, to differences in the hydrophobicity and ionic properties of its two components.

Synthetic oligonucleotides and their analogs have attracted considerable interest recently. These compounds may lead to highly specific therapeutic agents, as well as to powerful diagnostic tools. Here, we present the synthesis of uniformly modified oligodeoxyribonucleotide N3'-->P5' phosphoramidates containing 3'-NHP(O)(O-)O-5' internucleoside linkages and the study of their hybridization properties. Thermal dissociation experiments show that these compounds form very stable duplexes with single-stranded DNA, RNA, and with themselves following Watson-Crick base pairing. The duplex thermal stability was enhanced by 2.2-2.6 degrees C per modified linkage compared with phosphodiesters. The structure of complexes formed by phosphoramidates closely resembles that of RNA oligomers and corresponds to an A form, as judged by CD spectroscopy. N3'-->P5' phosphoramidates also form stable triplexes with double-stranded DNA under near-physiological conditions when natural phosphodiesters fail to do so. Physicochemical characteristics of the amidates are similar to those of RNA oligomers, even though they are composed of 2'-deoxyfuranose-based nucleosides.

Studies were performed to examine the mutational pattern of K-ras exons 1 and 2 and p53 exons 5-8 in lung cancer tissues from 27 Chinese patients (10 smokers, 17 non-smokers) using single-stranded conformational polymorphism and DNA sequencing. K-ras mutations were found in 13/27 tumors (48%); all mutations were clustered in exon 1 and distributed between codons 9 and 32. The frequency and number of patients with K-ras mutations between smokers and non-smokers were not different, except that a high frequency of G --> A transitions (11/11) was found in non-smokers. Among cell types, K-ras mutations were found in 7/13 (54%) squamous cell carcinoma (SC) and 5/12 (42%) adenocarcinoma (AC) patients. A --> T transversions (all six transversions) were present only in SC. In p53, 18/27 (67%) tumors contained mutations in exons 7 and 8, frequently at codons 226, 270, 275 and 281. The number of tumors with p53 mutations in smokers (70%) and in non-smokers (65%) was similar, and the mutation frequency did not differ except for a higher number of G --> A (6/7) and T --> C (5/6) transitions in non-smokers. Among cell types, the number of tumors with p53 mutations was 9/13 (69%) in SC and 8/12 (67%) in AC. The A --> G (11/16) transitions and A --> C (4/4) transversions in p53 were more frequent in SC than in AC (P < 0.04 for A --> G; P < 0.02 for A --> C). The varying mutation patterns in both the K-ras and p53 genes between smokers and non-smokers and among cell types suggest that other than cigarette smoke, environmental and dietary factors may also be involved in the genesis of lung cancer among these patients.

Myo-intimal proteoglycan metabolism is thought to be important in blood vessel homeostasis, blood clotting, atherogenesis, and atherosclerosis. Human platelet-derived transforming growth factor type beta (TGF-beta) specifically stimulated synthesis of at least two types of chondroitin sulfate proteoglycans in nonproliferating human adult arterial smooth muscle cells in culture. Stimulation of smooth muscle cell proteoglycan synthesis by smooth muscle cell growth promoters (epidermal growth factor, platelet-derived growth factor, and heparin-binding growth factors) was less than 20% of that elicited by TGF-beta. TGF-beta neither significantly stimulated proliferation of quiescent smooth muscle cells nor inhibited proliferating cells. The extent of TGF-beta stimulation of smooth muscle cell proteoglycan synthesis was similar in both nonproliferating and growth-stimulated cells. TGF-beta, which is a reversible inhibitor of endothelial cell proliferation, had no comparable effect on endothelial cell proteoglycan synthesis. These results are consistent with the hypothesis that TGF-beta is a cell-type-specific regulator of proteoglycan synthesis in human blood vessels and may contribute to the myo-intimal accumulation of proteoglycan in atherosclerotic lesions.

An efficient approach using the analytically decoupled near-tip displacement solution for bimaterial interface cracks presented in this paper involves: (1) the calculation of the decoupled strain energy release rates GI and GII associated respectively with the decoupled stress intensity factors KI and KII and (2) the extension of Rice's displacement derivative representation of Bueckner's weight function vectors beyond the homogeneous media. It is shown that the stress intensity factors for a bimaterial interface crack predicted by the present approach agree very well with those solutions available in the literature. The computational efficiency is enhanced through the use of singular elements in the crack-tip neighborhood.

Oligonucleotide analogs with N3'-->P5' phosphoramidate linkages bind to the major groove of double-helical DNA at specific oligopurine.oligopyrimidine sequences. These triple-helical complexes are much more stable than those formed by oligonucleotides with natural phosphodiester linkages. Oligonucleotide phosphoramidates containing thymine and cytosine or thymine, cytosine, and guanine bind strongly to the polypurine tract of human immunodeficiency virus proviral DNA under physiological conditions. Site-specific cleavage by the Dra I restriction enzyme at the 5' end of the polypurine sequence was inhibited by triplex formation. A eukaryotic transcription assay was used to investigate the effect of oligophosphoramidate binding to the polypurine tract sequence on transcription of the type 1 human immunodeficiency virus nef gene under the control of a cytomegalovirus promoter. An efficient arrest of RNA polymerase II was observed at the specific triplex site at submicromolar concentrations.

The kinetics of austenite decomposition were studied in high-purity Fe-0.1C-0.4Mn-0.3Si-X(concentrations in weight percent;Xrepresents 3Ni, 1Cr, or 0.5Mo) steels at temperatures between 500 °C and 675 °C. The transformation stasis phenomenon was found in the Fe-C-Mn-Si-Mo and Fe-C-Mn-Si-Ni alloys isothermally transformed at 650 °C and 675 °C but not in the Fe-C-Mn-Si and Fe-C-Mn-Si-Cr alloys at any of the temperatures investigated. The occurrence of transformation stasis was explained by synergistic interactions among alloying elements. The paraequilibrium model was applied to calculate the metastable fraction of ferrite in each alloy. This fraction was shown to coincide with cessation of transformation in the Mo alloy transformed at 600 °C. Transformation stasis was found in both the Ni and the Mo alloys isothermally reacted at 650 °C and 675 °C. The interactions among Mn, Si, and Mo, as well as interactions among Mn, Si, and Ni, appear to decrease the threshold concentrations for transformation stasis in Fe-C-Mn-Si systems. Segregation of Mn and Mo to the α/yγ boundary, assisted by the presence of Si, was suggested to enhance the solute draglike effect (SDLE) and lead to transformation stasis. In the Ni alloy, a lower driving force for ferrite formation resulting from the Ni addition could be responsible for the occurrence of transformation stasis.