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Morphological features of melt crystallized poly(9,9-di-n-octyl-2,7-fluorene) (PFO) were examined by means of polarized light microscopy, scanning electron microscopy, and transmission electron mic...

Self-assembled monolayers (SAMs) of triethyl phosphate (TEP) and the mixed SAMs of TEP with cetyltrimethyl ammonium bromide (CTAB) were prepared on copper surfaces. The protection abilities of these films against copper corrosion in 0.2 M NaCl aqueous solution were investigated using electrochemical impedance spectroscopy (EIS) and polarization techniques. Results showed that the inhibition efficiency (IE) increased with an increase in the immersion time of copper in the TEP-containing solutions. When the TEP films were modified with CTAB, the ability of the corrosion inhibition of the mixed films improved markedly. Furthermore, the influence of an external magnetic field on the formation of SAMs was studied. Ab initio calculations were performed to provide some theoretical studies for our experiment.

The conditioning and dewatering of phosphorus-rich biological sludge, obtained from a pilot-scale biological phosphorus removal plant, was investigated. Dual conditioning utilizing a polyampholyte (AC4601) in combination with aluminum chloride (AlCl3), ferric chloride (FeCl3), and calcium chloride (CaCl2) was studied. Capillary suction time (CST) and specific resistance to filtration (SRF) were utilized to assess sludge dewaterability. The dewaterability and removal of dissolved phosphorus from the phosphorus-rich sludge were examined. Compared with conditioning with only AC 4601, dual conditioning by adding 49 kg/ton of AlCl3 prior to addition of AC4601 resulted in formation of large flocs, better dewaterability, and removal of 50% of soluble phosphorus. Better dewaterability, even larger flocs (> 1 cm), and 75% removal of soluble phosphorus were found when dosage of AlCl3 increased to 189.2 kg/ton. The use of alumina (Al2O3) in combination with AC4601 could achieve equivalent dewaterability. However, on...

In a previous paper we combined calorimetric, diffraction and high-resolution quasi-elastic neutron scattering data to show that after exhibiting a glass transition at 165 K, interfacial water experiences a first order liquid-liquid transition at 240 K from a low-density to a high-density liquid. Here we present further evidence of these transitions obtained by high-energy inelastic neutron scattering.

In this work, a simplified model for on-chip spiral inductors was developed to accurately predict key parameters in the giga hertz range, i.e., peak quality factor Qpeak, frequency at peak quality factor fpeak, and self-resonance frequency fSR. To save area on the test-key layout, inductors were laid out with a ground-signal-ground-signal-ground (GSGSG) pad structure. In addition, we used two conventional ground-signal-ground (GSG) probes to measure the inductors with the GSGSG pad structures to save the cost of GSGSG probes. Very good fits between the predicted and the measured data indicate the suitability of the model and the new pad structure.

Standing Alfvén waves of 1.1 mHz (~15 min in period) were observed by the Cluster satellites in the mid-tail during 06:00-07:00UT on 8August 2003. Pulsations with the same frequency were also observed at several ground stations near Cluster's footpoint. The standing wave properties were determined from the electric and magnetic field measurements of Cluster. Data from the ground magnetometers indicated a latitudinal amplitude and phase structure consistent with the driven field line resonance (FLR) at 1.1 mHz. Simultaneously, quasi-periodic oscillations at different frequencies were observed in the post-midnight/early morning sector by GOES12 (l0≈8.7), Polar (l0≈11-14) and Geotail (l0≈9.8). The 8August 2003 event yields rare and interesting datasets. It provides, for the first time, coordinated in situ and ground-based observations of a very low frequency FLR in the mid-tail on stretched field lines.

At ambient pressure, bulk liquid water shows an anomalous increase of thermodynamic quantities and apparent divergences of dynamic properties on approaching a temperature Ts of 228 K. At normal pressure, supercooled water spontaneously freezes below the homogeneous nucleation temperature, TH = 235 K. Upon heating, the two forms of Amorphous Solid Water (ASW), LDA (Low Density Amorphous Ice) and HDA (High Density Amorphous Ice), crystallise above TX = 150 K. As a consequence, up to now no experiment has been able to explore the properties of liquid water in this very interesting temperature range between 150 and 235 K. We present nanosecond-time-scale measurements of local rotational and translational dynamics of interfacial, non-crystalline, water from 77 to 280 K. These experimental dynamic results are combined with calorimetric and diffraction data to show that after exhibiting a glass transition at 165 K, interfacial water experiences a first-order liquid-liquid transition at 240 K from a low-density to a high-density liquid. This is the first direct evidence of the existence of a liquid-liquid transition involving water.

Structural characteristics of optical quality poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phen- ylenevinylene) (MEH-PPV) films drop-cast from toluene solutions have been examined by use of wide- angle (WAXS) and small-angle X-ray scattering (SAXS) as well as field-emission scanning electron microscopy. For the as-cast film SAXS and WAXS patterns clearly suggest existence of nanodomains of mesomorphic order. Under grazing incidence, both SAXS and WAXS patterns of the as-cast film exhibit impressive uniaxial symmetry with strong scattering along the film normal; however, the corresponding normal-incidence patterns are circularly isotropic, implying in-plane random orientation. A structural model consisting of preferentially uniaxial-oriented nanodomains and disordered matrix is therefore proposed for the as-cast film. Annealing at 210 °C results in disorientation of nanodomains: this decrease in structural asymmetry upon heat treatment correlates well with concomitant changes in charge transport behavior determined from time-of-flight measurements, manifesting dramatically decreased charge mobility as well as transition from nondispersive to dispersive modes.

We synthesized dialkoxy-substituted poly[phenylene vinylene]s (dROPPV-1/1, 0.2/1, and 0/1) consisting of two repeating units with different side-chain lengths (methoxy and 3,7-dimethyloctyloxy). These polymers can serve as a model system to clarify roles of aggregates (the sites with ground-state interchain interactions) and the independent chain segments in the well-packed chains (the chain segments that are compactly packed without interaction) in the emission mechanism of conjugated polymers. Due to the packing of polymer chains, films of all of these polymers are accessible to interchain excitations, after which excitons can re-form to result in delayed luminescence. Besides, some chains form aggregates so that the delayed luminescence is no more the ordinary single-chain emission but red-shifted and less structured. Not only the re-formation of these indirect excitons but also the aggregation of chains are facilitated in the polymers with short methoxy side groups, revealing that both packing and aggregation of chain segments require a short spacing between polymer chains. However, the incorporation of other side chains such as the 3,7-dimethyloctyloxy group to dROPPVs is necessary for the formation of aggregates because these long branched side chains can reduce the intrachain order imposed by the short methoxy groups, which accounts for the absence of aggregate emission in the well-studied poly[2,5-dimethoxy-1,4-phenylene vinylene]. This study reveals that the well-packed chains do not necessarily form aggregates. We also show that the photophysical properties and the film morphology of conjugated polymers can be deliberately controlled by fine-tuning of the copolymer compositions, without altering the optical properties of single polymer chains (e.g., as in dilute solutions).

In this paper, a total of 60 concrete cylinders 30 cm in diameter and 60 cm in length confined by steel jackets of different thicknesses and different types of lateral steel reinforcements are tested to obtain the stress–strain curves of the cylinders. A constitutive model is proposed to describe the behavior of concrete confined by steel reinforcement, steel jackets, and both steel reinforcement and steel jackets used to retrofit and strengthen reinforced concrete structures. The confined concrete stress–strain curve of the proposed model is divided into two regions: the curve in the first region is approximated using a second-order polynomial equation, and that in the second region using an nth-order power-law equation, where n is a function of the unconfined concrete strength and the lateral confining stress. The results of the experiments show that different types of lateral steel reinforcement contribute greatly to the compressive strength of concrete cylinders confined by the reinforcement. Comparing the stress–strain curves of the uniaxial test with that from the proposed model, we conclude that the proposed model for concrete confined by a steel jacket and lateral steel reinforcement can predict the experimental results very well.Key words: constitutive model, steel jacket, confined concrete.

Direct and non-intrusive observations of crystallization and melting behavior of α and β polymorphs in bulk syndiotactic polystyrene were made by means of temperature-programmed x-ray diffraction. Results indicated that the highest sustainable temperature identifiable via wide-angle x-ray diffraction using stepwise annealing at increasingly higher temperatures (T a) for the perfected (with the initial crystallization temperature T c = 245 °C, followed by annealing at stepwise increased T a above 250 °C) α″ phase may be at least 286 °C. In a similar manner, the highest sustainable temperature of the perfected (with T c = 265 °C, followed by annealing at stepwise increased T a above 275 °C) β′ phase may be at least 280 °C. These observations suggest complete melting should occur only above the respective sustainable temperatures. It thus follows that equilibrium melting of the α and the β phases should occur at temperatures higher than 286 and 280 °C, respectively. Perfection of the less ordered α′ form into the better ordered α″ form within the α family is observed to occur in the vicinity of 270 °C; no evidence of transformation between α and β phases is identified.

By means of transmission electron microscopy (TEM) and X-ray diffraction (XRD) we demonstrate the presence of a previously unspecified modification (α‘) of the crystalline (α) phase in poly(9,9-di-...

We review our incoherent quasielastic neutron scattering (QENS) studies of the dynamics of supercooled water confined in nanoporous silica materials. QENS data were analysed by using the relaxing cage model (RCM) previously developed by us. We first use molecular dynamics (MD) simulation of the extended simple point charge model (SPC/E) for bulk supercooled water to establish the validity of the RCM, which applies to both the translational and rotational motion of water molecules. We then assume that the dynamics of water molecules in the vicinity of a hydrophilic surface is similar to a bulk water at an equivalent lower supercooled temperature. This analogy was experimentally demonstrated in previous investigations of water in Vycor glasses and near hydrophilic protein surfaces. Studies were made of supercooled water in MCM-41-S (pore sizes 25, 18, and 14 A) and MCM-48-S (pore size 22 A) using three QENS spectrometers of respective energy resolutions 1, 30, and 60 µeV, covering the temperature range from 325 to 200 K. Five quantities are extracted from the analysis: they are β, the stretch exponent characterizing the α-relaxation; βγ, the exponent determining the power-law dependence of the relaxation time on Q; , the Q-independent pre-factor for the average translational relaxation time; , the relaxation time for the first-order rotational correlation function; and , the relaxation time for the second-order rotational correlation function. We discuss the temperature dependence of these parameters and note that, in particular, the dynamics is rapidly slowing down at temperature around 220 K, signalling the onset of a structural arrest transition of liquid water into an amorphous solid water.

The effect of pH and different anions of sodium salts on concentrated solutions of cytochrome C protein have been investigated by means of small angle neutron scattering and viscosity measurements. The control and a fine tuning of protein–protein interactions leads to the formation of protein clusters that eventually evolve into a structural arrested state. The appearance of a low Q peak in the small angle neutron scattering intensity distributions is also accompanied by a strong increase in the relative viscosity. These phenomena taken together can be considered as the signature of the gelation process. This structural arrest is induced by salt addition and specifically depends on the nature of anions, according to the Hofmeister series.

Elevated temperature true stress – strain curves have been determined for the isothermal deformation of a TC6 titanium alloy using hot compression testing in the deformation temperature range 800 – 1040°C, strain rate range 0.001 – 50 s-1 and reduction in height of 30 – 50%. The experimental results show that the flow stress of TC6 titanium alloy is strongly dependent on process parameters, especially on the deformation temperature and strain rate. The peak stress and steady stress of such an alloy have the same characterisation, which increases with higher strain rate and lower deformation temperature. During isothermal forging, microstructural characterisation, including volume fraction, grain size, and grain pattern of prior α phase, varies with different temperatures, height reductions, and strain rates.

Presented are transmission electron microscopic observations of micron-sized single crystals of poly(9,9-di-n-octyl-2,7-fluorene) (PFO) prepared from thin films in the melt state. A preliminary determination of unit cell dimensions and molecular packing (orthorhombic, a = 2.56 nm, b = 2.34 nm, c = 3.32 nm, 8 chains, with space group P212121 and density 1.041 g mL-1) was made via combined considerations of the selected-area electron diffraction (SAED) pattern obtained along the [00l] zone of the single crystals, the SAED “fiber” pattern obtained from shear-oriented films, and the “powder” pattern from X-ray diffraction of melt-crystallized thick films in the absence of preferred orientation. In this model, PFO backbones are generally separated by transversely extended alkyl side chains, consistent with the dominance of single-chromophore emissions and the general lack of interbackbone delocalization of PFO chains in this ordered state as indicated by earlier photophysical studies. In addition, microscopic ...

Recent mode coupling theory (MCT) calculations show that in attractive colloids one may observe a new type of glass originating from clustering effects, as a result of the attractive interaction. This happens in addition to the known glass-forming mechanism due to cage effects in the hard sphere system. MCT also indicates that, within a certain volume fraction range, varying the external control parameter, the effective temperature, makes the glass-to-liquid-to-glass re-entrance and the glass-to-glass transitions possible. Here we present experimental evidence and details on this complex phase behavior in a three-block copolymer micellar system.

Proteins in concentrated solutions behave like colloidal system whose interaction potential can be finely tuned by changing temperature, pH, salt content and ion species. An anion-driven formation of protein clusters has been encountered eventually evolving in a structural arrested state as testified by both the appearance of a low Q peak in the small angle neutron scattering spectra and a strong increase in the relative viscosity of the samples. These phenomena, taken together, can be considered as the signature of a gelation process that specifically depends on the nature of anions, according to the Hofmeister series.

Thiol-derivatised cubic Ag nanoparticles were prepared by adding an AgNO3 solution containing a trace amount of alkanethiol into a solution of NaBH4 and sodium oleate. Their preparation and character were compared with randomly shaped Ag nanoparticles. The thiol was used purposely as orientation agent instead of protective agent. Transfer of cubic Ag nanoparticles from aqueous phase into organic phase or to the interface of aqueous/organic phase has resulted in self-assembled films on the surface of microscope slides and of many other substrates. Transmission electron microscope and UV-vis spectra were used to characterize the cubic Ag nanoparticles. The nanoparticle films were also observed using conventional optical and scanning electron microscope. The mechanisms of the nanoparticles phase-transfer and the formation of the self-assembled nanoparticle films are discussed. (C) 2004 Elsevier B.V. All rights reserved.

This paper investigates the stability robustness of linear output feedback systems with actuator saturation as well as both time-varying structured (elemental) and unstructured (norm-bounded) parameter uncertainties by directly considering the mixed quadratically coupled uncertainties in the problem formulation. Based on the Lyapunov approach and some essential properties of matrix measures, a new sufficient condition is proposed for ensuring that the linear output feedback systems with actuator saturation as well as both time-varying structured and unstructured parameter uncertainties are robustly stable. A numerical example is given to illustrate the application of the presented sufficient condition.

Structural evolution and its effect on the optical absorption/emission behavior of poly(2,5,2',5'-tetrahexyloxy-8,7'-dicyano-di-p-phenylenevinylene) (DH-CNPPV) upon short-term isothermal heat treatment at elevated temperatures were studied by means of a combination of X-ray diffraction, transmission electron microscopy, UV-vis spectroscopy, and photoluminescence spectroscopy. Results indicated kinetic preference for mesomorphic order in bulk DH-CNPPV, with the isotropization temperature (T i ) located in the vicinity of 210 °C. Upon heat treatment at elevated temperatures (T a ) below T i , supramolecular self-assembly of DH-CNPPV chains results in lamellar structure ca. 2.0 nm in layer spacing. This lamellar phase exists in the form of nanodomains (ca. 10-20 nm in diameter) that agglomerate into wormlike features with DH-CNPPV backbones and the mesomorphic lamellae lying transverse to the worm's long axis. Details in the selected-area electron diffraction pattern of shear-oriented specimens prescribe a short intraboard spacing of 0.38 nm and longitudinal displacement by one-third of the repeating unit between neighboring backbones, such that adequate interaction between the cyano group and the phenylene ring is allowed for. Accompanying the thermally induced morphological changes, UV-vis light absorption behavior varies consistently with improvement or disruption of the lamellar order whereas the major emission in the photoexcited spectrum shifts from 590 to 640 nm upon emergence of mesomorphic order, which is directly excitable and hence attributable to either extended backbone conjugation or enhanced interchain delocalization in the mesomorphic state. This is in dramatic contrast to the closely related case of poly(2,5-di-n-octyl-oxy-1,4-phenylenevinylene) (DO-PPV) without cyano substitutions in the backbone (for which excimer emission is the preferred mode upon morphological aggregation), signifying the role of specific cyano-phenylene interaction in the ground state of aggregated chains in the mesomorphic phase.

Flip chip package is the most important technology in IC package in terms of scale, velocity and cost in the development of semiconductor technology and the innovation of computer product. It has the advantage of low cost, low interface and small volume in IC package. This paper describes the analysis package of the solder ball and microchip for mold flow simulation (3D, midplane) and experiment. The numerical simulation of mold filling process is based on the concept of control volume finite element method. The injection point uses the corner, 1/4 side and central injection location. The injection process uses different parameters (mold temperature, injection temperature, injection pressure and injection time). For processing situation, the best result is from central injection, then 1/4 side injection and then corner injection. The results also show that the filling situation for 3D numerical simulation is closer to experiment.

Small angle neutron scattering (SANS) and rheological measurements have been used to study horse heart cytochrome C, a globular protein characterized by approximately spherical shape (a × b × b = 15 × 17 × 17 A3) with a molecular weight of 12 384 Da and a pI = 10.2. Two series of very concentrated protein solutions have been investigated at pD 5.4 and 11.0, respectively, the volume fraction of the protein spanning from 0.1 to 0.5. The Krieger–Dougherty model was applied to describe the relation between relative high shear viscosity of the solution and volume fraction of the protein at both pD in order to elucidate the charge effect on the interaction potential. The SANS intensity distributions at pD 5.4 were fitted using the GOCM model with an excellent agreement between the theory and experiments up to the volume fraction ϕ of 0.4. At pD 11.0 the intensity distribution at ϕ = 0.1 can be fitted with a pure form factor (oblate ellipsoid), suggesting that under this condition the cytochrome C molecules are almost uncharged and preserve the native molecular size. Addition of salt induces the transformation from liquid to a gel. This is a result of formation of ordered fractal clusters internally as evident from appearance of a second interaction peak at very low Q (magnitude of the scattering vector). The appearance of the low Q peak is also accompanied by a strong increase in the relative viscosity. These phenomena taken together can be considered as the signature of the gelation process.

Structural development in cast films of poly(2,5-di-n-octyloxy-1,4-phenylenevinylene) (DO-PPV) upon heat treatment was studied by means of polarized light microscopy, X-ray diffraction, ultraviolet−visible spectroscopy, and photoluminescence spectroscopy as well as scanning and transmission electron microscopy. Results indicated the dominance of a lamellar phase of biaxially refringent nematic-like texture upon short-term heat treatments at elevated temperatures (Ta) between 160 and 240 °C. A further increase in Ta results in dissipation of the mesomorphic order near the isotropization temperature Ti = ca. 300 °C. This lamellar phase, 1.8 nm in layer spacing at room temperature, typically consists of beads or grains approximately 10−20 nm in diameter that agglomerate into wormlike features in the absence of external stress. Mechanical shear right after high-temperature annealing results in disintegration of worms formed in the tranquil state; the constituent beads nevertheless reagglomerate into new worml...

The effect of nitrate on the general corrosion and pitting corrosion of iron was investigated in sulfate-based solutions with different pH values. Nitrate greatly accelerates the general corrosion of iron in acidic solutions, but has slight influence on the general corrosion in neutral solutions. The pitting inhibition of nitrate is dependent on the pH value of solutions, and nitrate is able to prevent the passivated iron surface from pitting attack only in acidic solutions. This pitting inhibition effect is probably associated with the competition between the passivating action of nitrate and depassivating action of chloride at passivated iron surfaces. The current oscillation characteristics for the iron in pure sulfuric acid (H2SO4) solution and in H2SO4 + NaNO3 + NaCl (sulfuric acid + sodium nitrate + sodium chloride) mixed solution were compared, and the relations between the oscillatory behavior and pitting susceptibility of iron were interpreted.

We report a set of viscoelastic measurements in aqueous solutions of a copolymer micellar system with attractive interactions, a system characterized by a percolation line (PT), and a structural arrest (SA) in the particle diffusion motions of a kinetic glass transition (KGT). We observe, in both transitions, dramatic variations in both the elastic (or storage G ′( ω )) and loss components ( G ″( ω )) of the shear moduli. At the PT, rheological data are characterized by a scaling behavior, whereas at the SA G ′ and G ″ develop a plateau and a marked minimum, respectively. These behaviors are described in the frame of percolation models and mode coupling theory (MCT).

Using three different quasielastic neutron spectrometers with widely different resolutions, we have been able to study the microscopic translational and rotational dynamics of water, in a mesoporous silica matrix MCM-48-S, from T=300 K to 220 K, with a single consistent model. We formulated our fitting routine using the relaxing cage model. Thus, from the fit of the experimental data, we extracted the fraction of water bound to the surface of the pore, the characteristic relaxation times of the long-time translational and rotational decays, the stretch exponent describing the shape of the relaxation processes, and the power exponent determining the Q-dependence of the translational relaxation time. A tremendous slowing down of the rotational relaxation time, as compared to the translational one, has been observed.

Using molecular dynamic simulations of an extended-simple-point-charge model of water, we investigated the effect of translation–rotation coupling on the motion of the hydrogen atom in a water molecule in low temperature water. We introduce a translation–rotation probability distribution PCM,Ω(r,θR,t), where r(t) is the scalar displacement of the center of mass from origin at time t starting from the origin at t=0; and θR(t)=arccos[b(t)⋅b(0)/b2] is the angle of rotation of the vector, b, connecting the center of mass of the water molecule to the hydrogen atom position. We developed a procedure to determine PCM,Ω(r,θR,t) starting from the van Hove self-correlation function of the center of mass, GsCM(r,t), taking into account the translation–rotation coupling effect. In the long time region, we use a translation–rotation coupling parameter, Q*, to determine the angular dependence of PCM,Ω(r,θR,t) from GsCM(r,t). Thus, the dynamics of the hydrogen atoms in a water molecule is fully determined by the van Hove self-correlation function of the center of mass and by the value of the translation–rotation coupling parameter. In particular, we show that the self intermediate scattering function of the hydrogen atom can be calculated with a better accuracy than using the traditional decoupling approximation. The model can be used to analyze incoherent quasielastic neutron scattering spectra of water in the future.

Mutations of receptor tyrosine kinases are implicated in the constitutive activation and development of human hematologic malignancies. An internal tandem duplication (ITD) of the juxtamembrane domain-coding sequence of the FLT3 gene (FLT3-ITD) is found in 20-25% of adult acute myeloid leukemia (AML) and at a lower frequency in childhood AML. FLT3-ITD is associated with leukocytosis and a poor prognosis, especially in patients with normal karyotype. Recently, there have been three reports on point mutations at codon 835 of the FLT3 gene (D835 mutations) in adult AML. These mutations are located in the activation loop of the second tyrosine kinase domain (TKD) of FLT3 (FLT3-TKD). The clinical and prognostic relevance of the TKD mutations is less clear. To the best of our knowledge, there has been no report to describe FLT3-TKD mutations in childhood AML. In this pediatric series, FLT3-TKD mutations occurred in three of 91 patients (3.3%), an incidence significantly lower than that of FLT3-ITD (14 of 91 patients, 15.4%) in the same cohort of patients. None of them had both FLT3-TKD and FLT3-ITD mutations. Sequence analysis showed one each of D835 Y, D835 V, and D835 H. Of the three patients carrying FLT3-TKD, two had AML-M3 with one each of L- and V-type PML-RARalpha, and another one had AML-M2 with AML1-ETO. None of our patients with FLT3-TKD had leukocytosis at diagnosis. At bone marrow relapse, one of the four patients examined acquired FLT3-ITD mutation and none gained FLT3-TKD mutation.

The robust stability problem of linear discrete singular time-delay systems with structured (elemental) parameter uncertainties is investigated. Under the assumptions that the nominal discrete singular time-delay system is regular, impulse-free and asymptotically stable, some new sufficient conditions are proposed to preserve the assumed properties when structured (elemental) parameter uncertainties are added into the nominal discrete singular time-delay system. Further new sufficient conditions are also proposed for guaranteeing that the linear discrete singular time-delay system with both structured (elemental) and unstructured (norm-bounded) parameter uncertainties has the properties of regularity, impulse-immunity and asymptotic stability. Four examples are given to demonstrate the applicability of the proposed sufficient conditions.

Self-assembled films of carbazole (CZ) and N-vinylcarbazole (NVC) were prepared on copper surfaces. The corrosion protection abilities of the films were evaluated in an air-saturated 0.5 mol dm(-3) NaCl solution using electrochemical impedance spectroscopy ( EIS), polarization and cyclic voltammetry. The results indicate that CZ and NVC form dense protective films on copper. Fourier transform infrared ( FTIR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the film. It was found that the NVC molecules are tilted at an angle to the copper surface. The theoretical ab initio calculations support the experimental results.

The domain orientations and lamellar interfaces play a critical role in the mechanical properties of TiAl based alloys. An umambiguous experimental determination of all six domain orientation in lamellar structure and the interfaces between neighboring γ laths in a (α 2 +γ) two-phase TiAl alloy containing Mn and Nb were analyzed by means of convergent-beam electron diffraction. The frequency of different interface types are reported.

Introduction. Electroluminescence (EL) properties of conjugated polymers have received widespread interest since 1990.1 A vast amount of effort was made on modification of chemical structure for purposes of color tuning or improvement of device performance.2 More recently, morphological effects in the light-emitting behavior of a representative conjugated polymer, poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV), have attracted some attention. This polymer has been considered as amorphous, with a glass transition (Tg) in the vicinity of 65 °C.3,4 A growing number of evidences have generally suggested the presence of “aggregate emission” (at wavelength λem ) ca. 640 nm) in solution-cast MEH-PPV films, which competes with single-chromophore exciton emission (λem ) ca. 580 nm) and low-efficiency excimer emissions (λem ) ca. 700 nm or higher).4-11 The term “excimer” refers to a neutral excited state shared between multichain segments in the absence of ground-state electron orbital overlap whereas “aggregates” have both the ground state and the excited state delocalized between multichain segments. These “aggregates”, already in existence in solutions above a moderate concentration threshold (on the order of 1% or less), may survive the film forming process (typically spin-coating) and affect significantly the light emission4,7,8 by the generation of interchain species that compete with the single-chain exciton.5-9 The “aggregation” in solution has previously been rationalized in terms of solvency power,7 although its exact physical identity is still a subject of controversy.11 Nevertheless, as emission from interchain species may be strongly enhanced after long-term annealing at an elevated temperature (i.e., several hours at 215 °C) after film formation,6 there arises a distinct possibility for the existence of a thermodynamically favored way of molecular packing in the bulk state. This would also be consistent with recent observations of increased optical heterogeneity in the submicron scale and decreased hole mobility upon heat treatment.10 Reported in this communication are our experimental findings that MEH-PPV is in fact mesomorphic in nature, with the tendency to form supramolecular assemblies with primitively layered structure (i.e., of smectic order) and yet maintaining its nematic-like optical texture upon heat treatment in the temperature range of 200-260 °C. Similarities in ultraviolet-visible light absorption and photoexcited emission behavior of heat-treated MEH-PPV as compared to reported aggregation effects in solution processed films appear to imply that the aggregates formed in solutions and the thermally induced supramolecular assemblies in the bulk state are structurally similar in terms of spatial arrangement of chain segments. Experimental Section. Poly(2-methoxy-5(2′-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV, chemical structure given as inset in Figure 4a) was synthesized via the Gilch method following in general the procedure reported by Wudl et al.12 Polarized light microscopic (PLM) observations were made by use of a Nikon Optiphot-Pol microscope equipped with a temperaturecontrolled stage. A Siemens D5000 diffractometer equipped with a copper target (KR line, with wavelength λ ) 0.154 nm), a graphite collimator, and a standard sample holder was used to obtain 1-D (“powder” ) X-ray diffraction (XRD) profiles at room temperature under a step-scan rate of 0.05° per 2 s in the scattering angle range of 2θ ) 1°-41°. Transmission electron microscopic (TEM) studies were performed using a JEOL 3010 instrument under an acceleration voltage of 150 kV. Optical absorption (UV-vis) and photoluminescence (PL) spectra of the film specimens were obtained by use of a LabGuide USB2000 instrument. Film specimens were drop-cast from toluene solutions on a quartz or glass substrate. Routine drying (ca. 4 h at 80 °C under vacuum) and heat-treatment (5 min at an elevated temperature under a protective stream of nitrogen, followed by fast cooling to room temperature) procedures were typically adopted to follow the thermally induced structural change or its effects on absorption/emission behavior. Oriented films were obtained via manual shearing at ca. 230 °C, followed by fast cooling to room temperature. For TEM studies, specimens were detached from the substrate using aqueous HF solutions and shadowed with platinum. Results and Discussion. Given in Figure 1 is a series of optical micrographs taken during heating and subsequent cooling of MEH-PPV. The optical texture is clearly nematic-like, with reversible thermochromic changes (from orange-red to orange-yellow) upon heating toward or cooling from its isotropization temperature (Ti) around 290 °C. For poly(9,9-dihexyl2,7fluorene) (PdHF) with comparable level of side-chain Figure 1. Polarized light micrographs of solution-cast MEHPPV film at a fixed heating/cooling rate of 20 °C/min in the temperature range of ambient to 300 °C: (a) as-cast film at room temperature; (b) heated to 100 °C, (c) 180 °C, and (d) 260 °C before passing the isotropization temperature of 290 °C. During cooling from 300 °C, the optical texture and the thermochromism were reversibly observed. 4229 Macromolecules 2002, 35, 4229-4232

Self-assembled monolayers (SAM) of a Schiff base were prepared on a copper surface under different conditions, and the quality and protection ability of resulting films against aqueous corrosion of copper were evaluated by alternating current (AC) impedance technique. Some factors, including surface treatment and applied potentials during and after self-assembly, were investigated. The results indicate that nitric acid (HNO3) etching of the copper prior to adsorption can improve the quality and corrosion inhibition ability of SAM significantly. An appropriately applied potential during self-assembly contributed to the improvement of the quality of SAM, and the long hydrocarbon chain in the molecular structure of the Schiff base enhanced the protection of SAM. Fourier transform infrared (FTIR) reflection spectroscopy and x-ray photoelectron spectroscopy (XPS) were used in the analysis of SAM.

A clipped random wave model (CRW) with an inverse 8th-order polynomial spectral density function (SDF) is proposed for the analysis of small-angle neutron scattering intensities from isometric bicontinuous microemulsions. The spectral density function contains three basic length scales which are essential in describing mesoscopic scale structures of porous materials. The scattering intensities from ionic and non-ionic bicontinuous microemulsions were analyzed using the model to obtain the average Gaussian and square mean curvatures, the specific interfacial area and the bending rigidity constant.

We propose a new method for the analysis of high-resolution incoherent quasi-elastic neutron scattering spectra of water in porous media and apply it, in particular, to a case of water in hydrated tricalcium silicate. We plot the normalized frequency-dependent susceptibility as a function of a scaling variable ω/ωp, where ωp is the peak position of the α-relaxation. In this way, we are able to scale QENS data from a range of Q into a single master curve. We then fit this master curve with an empirical formula for the susceptibility proposed by Bergman (J. Appl. Phys. 88 (2000) 1356) to obtain three independent parameters previously introduced by us to describe the dynamic state of hydration water in a curing cement paste. Specifically, we extract q, β, and τ where, q is the fraction of glassy water, and β and τ the two parameters associated with the α-relaxation of the glassy water.

shandong univ, dept chem, jinan 250100, peoples r china. state key lab corros & protect, shenyang 110015, peoples r china.;chen, sh (reprint author), shandong univ, dept chem, jinan 250100, peoples r china

Compared to conventional thermal imprinting using a flat mold, roll-to-roll (R2R) thermal imprinting using a roller mold is a high-speed, high through-put process. In an R2R thermal imprinting process, however, the contact duration between a mold and a thermoplastic substrate is extremely short. This results in insufficient heating and pressing, leading to low fidelity of the imprinted microstructures. We have developed an R2R thermal imprinting system, which allows us to extend the contact duration between the mold and substrate. This system consists of two continuous, seamless belts that are made of metal foil. Each belt is driven by an individual hot roller; at least one belt is used as an imprinting mold, another as a carrier belt. A thermoplastic film to be imprinted is sandwiched between the two belts that provide preheating, heating and pressing, holding, and cooling for demolding during imprinting, leading to extended mold-substrate contact duration and enhanced heat transfer from the belt mold to the polymer film. R2R thermal imprinting has been performed successfully and promising results have been demonstrated.

Article history: The effect on the selection of different plasma chemistries for simulating a typical dielectric barrier discharge (DBD) driven by quasi-pulsed power source (20 kHz) is investigated. The numerical simulation was performed by using the one-dimensional self-consistent fluid modeling solver. Our simulation result indicates that the computed temporal current density can be significantly improved by using a complex version of plasma chemistry module rather than the simple one and demonstrates an excellent agreement with the experimental data. The result suggests the metastable, excited and ionic helium related reaction channels, which are important in simulating a DBD, should be taken into account. Furthermore, it also reveals that the power absorption of ions is considerably higher than that of the electron.

In order to maximize Cu volume and reduce via resistance, barrier thickness reduction is a strong option. Alternative barriers for next-generation BEOL were evaluated in terms of barrier performance to O 2 and Cu diffusion, and effects on reliability. A clear correlation of O 2 barrier performance to electromigration was observed, suggesting that the key role of the barrier layer is to prevent oxidation of Cu or the Cu/barrier interface. Long-throw PVD-TaN showed superior O 2 barrier performance to alternative metals such as PEALD-TaN, thermal ALD-TaN, -TaN(Mn) and - MnN and MnSiO3 self-forming barrier.

We investigated genetic susceptibility to coronary artery disease (CAD) by studying the association of MKL1 gene polymorphisms with CAD in the Chinese Han population. We performed a case-control study with 476 unrelated CAD patients and 325 non-CAD controls. All SNPs were genotyped with a TaqMan SNP genotyping assay. The distribution of MKL1-184CT gene polymorphism in each group was in Hardy-Weinberg equilibrium. The frequency of the MKL1 T allele in the CAD group was significantly higher than in the control group (38.6 vs 30.8%). After logistic regression models adjusted for CAD risk factors, the risk of CAD among CT genotypes was 1.765 times higher than among the CC genotypes [odds ration (OR) = 1.765, 95% confidence interval (CI) = 1.246-2.5], and for TT genotypes it was 1.806 times higher than for the CC genotypes (OR = 1.806, 95%CI = 1.203-2.71). In summary, genotypes with at least one T allele (CT or TT genotypes) had a significantly increased CAD risk than the CC genotypes, with a ratio of 1.78 to 1 (OR = 1.780, 95%CI = 1.311-2.418). There was a close association between -184 T allele and 3VD (OR = 1.614, 95%CI = 1.259-2.07, P0.05). We conclude that the -184CT of MKL1 is an important susceptibility factor for CAD in the Han Chinese in Henan Province. Homozygosity for the T allele is not only associated with an increased risk for CAD, it is also correlated with severity of stenosis in the Chinese Han population.

The aim of this study was to determine the potency and molecular mechanism of action of YM155, a first-in-class survivin inhibitor that is currently under phase I/II clinical investigations, in various drug-resistant breast cancers including the oestrogen receptor positive (ER(+) ) tamoxifen-resistant breast cancer and the caspase-3-deficient breast cancer.The potency of YM155 in SK-BR-3, MDA-MB-231, MCF7 and its tamoxifen-resistant sublines, TamR6, TamR7, TamR8, TamC3 and TamC6, were determined by MTT assay. Western blot analysis, flow cytometric analysis, reverse transcription-PCR, fluorescent microscopy and comet assay were used to determine the molecular mechanism of action of YM155 in different breast cancer cell lines.YM155 was equally potent towards the parental ER(+) /caspase-3-deficient MCF7 breast cancer cells and its tamoxifen-resistant sublines in vitro. The ER(-) /HER2(+) SK-BR-3 breast cancer cells and the triple-negative/caspase-3-expressing metastatic aggressive MDA-MB-231 breast cancer cells were also sensitive to YM155 with IC50 values in the low nanomolar range. Targeting survivin by YM155 modulated autophagy, induced autophagy-dependent caspase-7 activation and autophagy-dependent DNA damage in breast cancer cells. Interestingly, YM155 also induced XIAP degradation and the degradation of XIAP might play an important role in YM155-induced autophagy in breast cancer cells.YM155 is a potent survivin inhibitor that has potential for the management of various breast cancer subtypes regardless of the expression of ER, HER2 and caspase-3. Importantly, this study provides new insights into YM155's molecular mechanism of action and therapeutic potential in the treatment of tamoxifen-resistant breast cancer.

In this work, we study a copolymer-micellar system characterized by clustering processes due to a short-range attractive interaction. This originates a percolation process and a new type of kinetic glass transition. We have studied these intriguing dynamical situations by means of an extensive set of light scattering and viscoelasticity experiments. Obtained data, in both the phenomena, are accounted for by considering in a proper way fractal clustering processes and the related scaling concepts. Near the percolation line the main role in the system structure and dynamics is played by the cluster's partial screening of hydrodynamic interaction, that behaves, on approaching the percolation threshold, dramatic effects on the rheological properties and on the density decay relaxations. The ergodic–nonergodic transition line (glass transition) is studied in terms of the intermediate scattering functions (ISF) in the frame of the mode coupling theory. The measured ISF gives evidence of a logarithmic decay on the density fluctuation followed by a power law behavior. This latter phenomenon is the signature of a high-order glass transition of the A3 type (cusp-like singularity).

Some interesting magnetic properties were observed after Ag ultrathin films were deposited on Co/Pt(1 1 1). The spin reversal of Co can be prevented when Ag atoms cap Co on Pt(1 1 1). The out-of-plane magnetization has a significant enhancement after annealing at high temperature. The Curie temperature increases from 625 to 710 K as 1 ML of Ag is deposited on 1 ML Co/Pt(1 1 1). The change of surface anisotropy and the formation of a Co–Pt alloy are possible mechanisms for the magnetization enhancement.