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ConspectusDespite advances in genome sequencing technology, the complete molecular interaction networks reflecting the biological functions of gene products have not been fully elucidated due to the lack of robust molecular interactome profiling techniques. Traditionally, molecular interactions have been investigated

Photo-caged benzaldehyde probes using o-nitrophenylethylene glycol were designed for photo-activated electrophile generation.

Aberrantly elevated steroid receptor coactivator-1 (SRC-1) expression and activity are strongly correlated with cancer progression and metastasis. Here we report, for the first time, the development of a proteolysis targeting chimera (PROTAC) that is composed of a selective SRC-1 binder linked to a specific ligand for UBR box, a unique class of E3 ligases recognizing N-degrons. We showed that the bifunctional molecule efficiently and selectively induced the degradation of SRC-1 in cells through the N-degron pathway. Importantly, given the ubiquitous expression of the UBR protein in most cells, PROTACs targeting the UBR box could degrade a protein of interest regardless of cell types. We also showed that the SRC-1 degrader significantly suppressed cancer cell invasion and migration in vitro and in vivo. Together, these results demonstrate that the SRC-1 degrader can be an invaluable chemical tool in the studies of SRC-1 functions. Moreover, our findings suggest PROTACs based on the N-degron pathway as a widely useful strategy to degrade disease-relevant proteins.

The high temperature requirement A (HTRA) family of serine proteases mediates protein quality control. These proteins process misfolded proteins in several diseases including Alzheimer's disease (AD) and Parkinson's disease (PD). While their structures and activation mechanisms have been studied, the precise details of the regulation of their activity under physiological conditions have not been completely elucidated, partly due to the lack of suitable chemical probes. In the present study, we developed novel activity-based probes (ABPs) targeting the HTRAs and demonstrated their utility in the monitoring and quantification of changes in enzyme activity in live cells. Using our probes, we found the activity of HTRA1 to be highly elevated in an AD-like cell-based model. We also observed the active HTRA2 in live cells by using a mitochondrion-targeted probe. We believe that our probes can serve as a useful tool to study the role of human HTRAs in neurodegenerative diseases.

Correction for ‘Temporal control of protein labeling by a photo-caged benzaldehyde motif and discovery of host cell factors of avian influenza virus infection’ by Nicholas Asiimwe et al., Chem. Commun., 2022, https://doi.org/10.1039/d2cc04091c.

Isothermal oxidation behavior of NbSi 2 coating grown on Nb substrate was investigated in air at 1000–1450 °C. Oxidation rate of NbSi 2 coating increased with temperature at 1000–1300 °C but opposite trend was observed at 1300–1450 °C. Maximum oxidation rate was obtained at 1300 °C due to the highest porosity of oxide scale. Lowest oxidation rate was observed at 1450 °C due to formation of dense oxide scale by combined effect of volatilization of Nb oxide phase, viscous flow and densification of c-SiO 2 . Oxidation resistance of NbSi 2 coating at these temperatures was governed by some inter-related factors.

Despite of many attractive properties of TiO2, the drawback of TiO2 ceramic is low fracture toughness for widely industrial application. The method to improve the fracture toughness and hardness has been reported by addition of reinforcing phase to fabricate a nanostructured composite. In this regard, graphene has been evaluated as an ideal second phase in ceramics. Nearly full density of nanostructured TiO2-graphene composite was achieved within one min using pulsed current activated sintering. The effect of graphene on microstructure, fracture toughness and hardness of TiO2-graphene composite was evaluated using Vickers hardness tester and field emission scanning electron microscopy. The grain size of TiO2 in the TiO2-x vol% (x = 0, 1, 3, and 5) graphene composite was greatly reduced with increase in addition of graphene. Both hardness and fracture toughness of TiO2-graphene composites simultaneously increased in the addition of graphene.

4YSZ is generally used as oxygen sensors, fuel cells, thermal barrier and hip and knee joint replacements as a result of these excellent properties with its high biocompatibility, low density, good resistance against corrosion, high ionic conductivity, hard phase and melting point. However, 4YTZ with coarse grain has low resistance to wear and abrasion because of low hardness and low fracture toughness at room temperature. The fracture toughness and hardness of a 4YTZ can be improved by forming nanostructured composites and addition of a second hard phase. In this study, nanostuctured 4YTZ-graphene composites with nearly full density were achieved using high-frequency induction heated sintering for one min at a pressure of 80 MPa. The rapid consolidation and addition of graphene to 4YTZ retained the nano-scale structure of the ceramic by inhibiting grain growth. The grain size of 4YTZ was reduced remarkably by the addition of graphene and the addition of graphene to 4YTZ greatly improved the fracture toughness without decrease of hardness.

The rapid sintering of ultra-fine WC–Al 2 O 3 composites in a short time was investigated with a focus on the mechanical properties and consolidation using pulsed current activated sintering. The advantage of this process is that it allows very quick densification to near theoretical density and prohibition of grain growth in nanomaterials. The addition of Al 2 O 3 to WC can facilitate consolidation and improve mechanical properties. The hardness and fracture toughness of WC–Al 2 O 3 composites outperform those of monolithic Al 2 O 3 .

Ti and CNT powders were milled by high energy ball milling. The milled powders were then simultaneously synthesized and consolidated using pulsed current activated sintering (PCAS) within one minute under the applied pressure of 80 MPa. The advantage of this process is not only rapid densification to near theoretical density but also to prevent grain growth in nano-structured materials The milling did not induce any reaction between the constituent powders. Meanwhile, PCAS of the Ti-CNT mixture produced a Ti-TiC composite according to the reaction (Ti + 0.06CNT --> 0.94Ti+0.06TiC, Ti+0.12CNT --> 0.88Ti+0.12TiC). Highly dense nanocrystalline Ti-TiC compos- ites with a relative density of up to 99.5% were obtained within one minute. The hardness and fracture toughness of the dense Ti-6mole% TiC and Ti-12 mole% TiC produced by PCAS were also investigated.

The ultra-small angle neutron scattering (USANS) measures the microscale structure of heterogeneity and the scattering from rough surfaces with small scattering volumes can be neglected. But this is not true in amorphous alloys. The small angle scattering from such surfaces is not negligible, regardless of scattering volume. However, we demonstrate that the unwanted rough surfaces can be utilized to determine the homogeneity and mass density of amorphous metallic glasses using the USANS and surface neutron contrast matching technique. The power law scattering of the homogeneous Cu50Zr50 amorphous alloy disappeared under the surface contrast-matched environment, a mixture of hydrogenated/deuterated ethanol having low surface tension against the metallic alloys, indicating that the scattering originated not from its internal structure but from the rough surface. This confirms the structural homogeneity not only at the atomic level but also on a larger scale of micrometer. On the other hand, the crystallized Cu50Zr50 alloy showed strong power-law scattering under the matching environment due to the structural heterogeneity inside the alloy. This technique can apply to the bulk samples when the transmission is high enough not causing multiple scattering that is easily detected with USANS and when the surface roughness is dominant source of scattering.

Metal-ceramic compositr can be obtained with an optimum combination of low density, high oxidation resistance, and high hardness of the ceramic and toughness of the metal. Therefore, metal matrix composites are recognized as candidates for aerospace, automotive, biomaterials, and defense applications. Despite its many attractive properties, the low fracture toughness of ZrO2 limits its wide application. One of the most obvious tactics to improve the mechanical properties has been to fabricate a nanostructured material and composite material. Nano-powders of Cu and ZrO2 were synthesized from 2CuO and Zr powders by high-energy ball milling. Nanocrystalline 2Cu-ZrO2 composite was consolidated within 5 minutes from mechanically synthesized powders of ZrO2 and 2Cu at low temperature, by a pulsed current activated sintering method. The relative density of the composite was 98.5%. The fracture toughness of 2Cu-ZrO2 composite in this study is higher than that of monolithic ZrO2, without great decrease of hardness.

Nanopowders of MgO, Al2O3 and SiO2 were made by high energy ball milling. The rapid sintering of nanostuctured Al2O3-MgSiO3 composites was investigated by the high-frequency induction heating sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibits grain growth. Highly dense nanostructured Al2O3-MgSiO3 composites were produced with the simultaneous application of 80 MPa pressure and the induced output current of total power capacity (15 kW) within 2 min. The sintering behavior, grain size and mechanical properties of Al2O3-MgSiO3 composites were investigated.

Nanopowders of Fe and ZrO2 were synthesized from Fe2O3 and Zr by high-energy ball milling. The powder sizes of Fe and ZrO2 were 70 nm and 12 nm, respectively. Highly dense nanostructured 4/3Fe-ZrO2 composite was consolidated by a pulsed current activated sintering method within 1 minute from the mechanically synthesized powders (Fe-ZrO2) and horizontal milled Fe2O3+Zr powders under the 1 GPa pressure. The grain sizes of Fe and ZrO2 in the composite were calculated. The average hardness and fracture toughness values of nanostuctured 4/3Fe-ZrO2 composite were investigated.

Highly ordered TiO2 nanotube arrays were prepared using a self-templating multi-step anodic oxidation process in a fluoride-containing electrolyte. The microstructures, chemical compositions, and phases of the self-organized TiO2 nanotube arrays were analyzed by FESEM, XPS, and XRD, respectively. Hexagonal packing density in TiO2 nanotube arrays significantly improved after the the multi-step anodic oxidation. The area densities of the hexagonal TiO2 nanotube arrays increased approximately 3 times from the first to second step in the anodic oxidation steps process (4.9 μm−2 to 16.4 μm−2), but there was no difference between the second and third step (16.4 μm−2 to 16.0 μm−2). The as-anodized TiO2 nanotube array had an amorphous structure and it transformed to an anatase phase during the annealing process at 450 °C for 1 h. The as-anodized TiO2 nanotube arrays adsorbed the fluoride, hydrocarbon groups (CH), hydroxyl groups (OH, C-OH), and carboxyl groups (O = C-OH) on their surfaces.

Growth behavior and microstructure of oxide scales formed on WSi 2 coating by isothermal oxidation between 800 and 1300 °C were investigated. At and below 1000 °C, lamellar WO 3 embedded in the amorphous SiO 2 matrix was formed from the direct oxidation of WSi 2 by inward diffusion of oxygen through short-circuit paths. At the intermediate temperatures between 1100 and 1200 °C, fastest oxidation rate was observed. The oxide scale consisted of the spheroidal WO 3 particles embedded in the amorphous SiO 2 matrix. WSi 2 was initially oxidized to form W 5 Si 3 and SiO 2 followed by the oxidation of W 5 Si 3 to form WO 3 and SiO 2 phases. At 1300 °C, oxide scale consisted of continuous cristobalite SiO 2 and W 5 Si 3 layer underneath, leading to the slowest isothermal oxidation behavior. It is concluded that the interplay of phase stability of WSi 2 , defect formation process, and viscosity of SiO 2 gives rise to unique and complex oxidation behavior especially at intermediate temperatures.

Ferritic steels have been candidate structural materials for first wall and blanket structures of fusion power plant since the late 1970’s, when the fast-reactor irradiation showed them to be more swelling resistant than austenitic stainless steels. In this investigation, the coarsening of MX nitrides during aging was studied for Cr-Mo-N-X(X=V, Nb, Ti) ferritic steels. During the aging, (V, Nb, Ti)nitrides were precipitated out. From TEM observation, particle size distribution was confirmed and size distribution follows a typical log-normal distribution. The coarsening rate of MX nitrides was correlated with the Oswald ripening equation.

An attempt was made to coat bio-active calcium phosphate on a titanium substrate by room temperature blasted-coating process as an alternative for conventional thermal spray or ion beam-assisted coating techniques. Thickness, surface roughness, crystallinity, and Ca and P-dissolution behavior of the coated layer were investigated as a function of pressure and time of the blasted coating process. The blasted coating process offered comparable coating characteristics with those of conventional techniques, including a thickness of 1.3 pm∼ 6.3 pm, and a surface roughness of 1.5∼ 2.3 μm. Furthermore, the blasted coating layer showed higher crystallinity and more favorable dissolution behavior (i.e., constant and long-lasting release of Ca and P) than those of the convention thermal processes. Based on the comparable or superior characteristics of the blasted coating process at room temperature, it was suggested as a useful technique for calcium phosphate coating on Ti-based medical device.

Dense nanostructured TiSi 2 –SiC composite was synthesized by high-frequency-induced heated combustion synthesis method within 1 min in one step from TiC and 3Si powders. Simultaneous combustion synthesis and densification were accomplished under the combined effects of an induced current and mechanical pressure. Highly dense TiSi 2 –SiC with relative density of up to 99% was produced under the simultaneous application of a 60 MPa pressure and the induced current. The mechanical properties of the composite were investigated.

Bulk metallic glasses are adequate for micro-forming because of the viscous flow in the supercooled liquid state. The deformation behavior of Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 alloy under compression in the supercooled liquid state were investigated by using DSC and TMA. Based on the deformation behavior, micro-forming process of Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 alloy was designed and carried out. The surface of the deformed specimens were analyzed by SEM, XRD, and AFM. The roughness of the specimen surface exhibited a correlation with the total deformation and a new parameter reflecting roughness evolution of the deformed surface was suggested as the relative comparison among different forming conditions.

The crystallization behavior of Cu and Zr-base Bulk Metallic Glass were investigated using the electrical resistivity measurements in isothermal annealing. Electrical resistivity evolutions exhibited one or two stage of resistivity reduction according to additional elements respectively. In order to analyze the electrical resistivity reduction, micro structure evolutions were analyzed using DSC, XRD, and TEM.

The microstructure and oxidation resistance of MSi2-SiC or MSi2-Si3N4 nanocomposite coatings (M = Mo, W, Nb, Ta) on M substrates formed by displacement reactions between M-carbides or M–nitrides and silicon, respectively, was investigated. Present study demonstrated that the crack density formed in the MSi2-base nanocomposite coatings due to mismatch in the coefficient of thermal expansion between nanocomposite coatings and M substrates could be controlled by adjusting the volume fraction of the SiC or Si3N4 reinforcing particles with the low CTE values. The high- and low-temperature oxidation resistance of nanocomposite coatings was superior to that of monolithic MSi2 coatings.

Plasma electrolytic oxidation (PEO) has drawn attention and been studied intensively all through the world. The thick ceramic coatings fabricated by the technique exhibit excellent properties, including hardness and wear resistance, thermal and electrical insulation, and corrosion resistance, due to the characteristic phase composition and microstructure of the coating layers. However, most of the studies have dealt with manufacturing process itself and the apparent properties of coating layers and researches on the microstructural basis including transmission electron microscopy analysis are limited so far. In this investigation, a basic approach to PEO process was tried, adapting time-potential behavior analysis under constant current mode (galvanostatic) oxidation, and microstructural analysis on the coating structure, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The time-potential behavior analysis under constant current DC was carried out, and the resultant evolution of the microstructure was characterized..

The crystallization behavior of Cu 43 Zr 43 Al 7 Ag 7 (numbers indicate at.%) bulk metallic glass was investigated using the isothermal electrical resistivity measurements at 450 °C in the supercooled liquid region. The crystallization process is a single step phase transformation. To analyze the electrical resistivity reduction, microstructure evolutions were analyzed using differential scanning calorimetry, X-ray diffraction, transmission electron microscopy and small-angle X-ray scattering. The Avrami parameter of the electrical resistivity reduction step was 1.73, indicating that the crystallization process is a diffusion-controlled growth of intermetallic compounds with decreasing nucleation rate.

By the high frequency induction heated combustion synthesis (HFIHCS) method, dense nanostructured TaSi2-SiC composite was synthesized within 2 minutes and in a single step from powders of TaC and 3Si. Simultaneous combustion synthesis and densification were accomplished under the combined effects of an induced current and mechanical pressure. Highly dense TaSi2-SiC with relative density of up to 97% were produced under a 60MPa pressure and induced current. The average grain size and mechanical properties (hardness and fracture toughness) of the composite were investigated.

Dense nanostructured NbSi 2 –SiC composite was synthesized by high-frequency induction heated combustion synthesis (HFIHCS) method within 2 min in one step from powders of NbC and 3Si. Simultaneous combustion synthesis and densification were accomplished under the combined effects of an induced current and mechanical pressure. Highly dense NbSi 2 –SiC with relative density of up to 99.8% were produced under simultaneous application of a 60 MPa pressure and the induced current. The average grain size and mechanical properties (hardness and fracture toughness) of the composite were investigated.

The low-temperature cyclic oxidation behavior of MoSi 2 /(12.9∼17.7) vol.% Si 3 N 4 nanocomposite coating formed on a Mo substrate in air at 500 °C was investigated and compared with that of the monolithic MoSi 2 coating using field-emission scanning electron microscopy (SEM) and cross-sectional transmission electron microscopy (XTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The nanocomposite coating was produced by a prior ammonia nitridation followed by chemical vapor deposition of Si on a Mo substrate. While the accelerated oxidation behavior was observed for the monolithic MoSi 2 coating after an incubation period, no pest oxidation but a fairly rapid rate of low-temperature oxidation was observed in the nanocomposite coating with increasing oxidation cycles. The good low-temperature cyclic oxidation resistance of the nanocomposite coating was attributed to the limited formation of massive MoO 3 precipitates by reducing the oxygen concentration in oxide scale through the preferential oxidation of Si 3 N 4 particles followed by oxidation of MoSi 2 phase. However, fairly rapid oxidation resulted from the crack formation that resulted from the evaporation of nitrogen gas released by oxidation of Si 3 N 4 particles at longer cycles.

The microstructure and oxidation property of NbSi2/α-Si3N4 nanocomposite coating formed on Nb substrate by a prior nitridation process followed by pack siliconizing process were investigated. The Nb-nitride layers formed by nitridation process at 1300 °C consisted of two layers, i.e. the outer layer of mixed nitrides of NbN and Nb4N3 and the inner layer of Nb2N. While the monolithic NbSi2 coating showed the typical columnar microstructure perpendicular to the Nb substrate, the NbSi2/α-Si3N4 nanocomposite coating formed by the solid-state displacement reaction of the outer Nb-nitride layer with Si was composed of the equiaxed NbSi2 grains and the α-Si3N4 particles with the oblate-spheroidal shape, which were mostly located at the grain boundaries of NbSi2. The average size of equiaxed NbSi2 grains and α-Si3N4 particles were about 44–125 and 33–45 nm, respectively. The nanocomposite coating formed by the solid-state displacement reaction of the inner Nb-nitride layer with Si showed the columnar microstructure. The average diameters of NbSi2 grains and the α-Si3N4 particles were about 255 and 43 nm, respectively. The volume percentage of α-Si3N4 particles ranged from 16.8 to 24.4% with respect to nitrogen concentration in Nb-nitride layers. No cracks were observed in the nanocomposite coating, indicating that its thermal expansion coefficient was close to that of Nb substrate. The isothermal oxidation resistance of NbSi2/α-Si3N4 nanocomposite coating in 80% Ar–20% O2 atmosphere at 1100 °C was superior to that of monolithic NbSi2 coating.

The crystallization behavior of the Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass was investigated using the isothermal electrical resistivity measurements at 390 °C in the super-cooled liquid region. The crystallization process is completed through two sequential phase transformations. The first phase transformation was the formation of icosahedral phases, which is followed by the formation of intermetallic compounds.

Growth kinetics of the W 5 Si 3 layer in the WSi 2 /W diffusion couple was investigated using optical microscopy, field-emission scanning electron microscopy, cross-sectional transmission electron microscopy, and X-ray diffraction. The 62 μm WSi 2 /0.3 μm–W 5 Si 3 /W diffusion couple was made by chemical vapor deposition (CVD) of Si on a W substrate. When the diffusion couple was annealed at temperatures between 1300 and 1500 °C in an argon atmosphere, the W 5 Si 3 layer was simultaneously formed both at the surface of the WSi 2 layer and at the interface between the WSi 2 layer and the W substrate. The W 5 Si 3 layer observed at the surface of WSi 2 layer was formed by loss of Si released from the decomposition of WSi 2 phase into the W 5 Si 3 and Si phases. The growth kinetics of W 5 Si 3 layer formed at the interface between the WSi 2 layer and the W substrate obeyed a parabolic rate law, indicating the diffusion-controlled growth. From the change of columnar diameter and texture of W 5 Si 3 grains, the dominant diffusion element and growth mechanism of the W 5 Si 3 layer was found. The integrated interdiffusion coefficients in the W 5 Si 3 phase were determined.

Growth behavior and microstructure of oxide scale formed on MoSi2 coating by cyclic oxidation testing in air at 500 °C were investigated using field emission scanning electron microscopy, cross-sectional transmission electron microscopy, glancing angle x-ray diffraction, and x-ray photoelectron spectroscopy. MoSi2 coating was prepared by chemical vapor deposition of Si on a Mo substrate at 1100 °C for 5 h using SiCl4–H2 precursor gas mixtures. After the incubation period of about 454 cycles, accelerated oxidation behavior was observed in MoSi2 coating and the weight gain increased linearly with increasing oxidation cycles. Microstructural analyses revealed that pest oxide scale was formed in three sequential processes. Initially, nanometer-sized crystalline Mo4O11 particles were formed with an amorphous SiO2 matrix at MoSi2 interface region. Inward diffusing oxygen reacted with Mo4O11 to form Mo9O26 nano-sized particles. At final stage of oxidation, MoO3 was formed from Mo9O26 with oxygen and growth of MoO3 took place forming massive precipitates with irregular and wavy shapes. The internal stress caused by the growth of massive MoO3 precipitates and the volatilization of MoO3 was attributed to the formation of many lateral cracks into the matrix leading to pest oxidation of MoSi2 coating.

The mechanically alloyed (Al + 12.5 at.% Cu) 3 Zr powders were consolidated by cold isostatic pressing (CIP) and subsequent sintering. Effects of CIP pressure and sintering temperature on the stability of metastable L1 2 phase and nanocrystalline structure were investigated. Before sintering, the powders were CIPed at 138, 207, 276, and 414 MPa. The relative densities of the CIP compacts were not greatly affected by the CIP pressure. However, the L1 2 phase of the specimen CIPed at pressures greater than 276 MPa was partially transformed into D0 23 . The optimum consolidation conditions for maintaining L1 2 phase and nanocrystalline microstructure were determined to be CIP at 207 MPa and sintering at 800 °C for 1 h for which the grain size was 34.2 nm and the relative density was 93.8%. Full density specimens could be prepared by sintering above 900 °C, however, these specimens consisted of L1 2 and D0 23 phases. The grain sizes of all the specimens were confirmed by TEM and XRD, and were found to be less than 40 nm. This is one of the smallest grain sizes ever reported in trialuminide intermetallic compounds.

Effects of Mn addition on microstructure, phase stability and mechanical properties of (Al+ x at.%Mn) 3 Ti intermetallic compounds fabricated by mechanical alloying and spark plasma sintering were investigated. As-milled ternary powders consist of homogeneous distribution of fine crystallites in amorphous matrix. (Al+0.08 Mn) 3 Ti showed the most stable thermal stability with average grain sizes of less than 60 and 100 nm after heat treatments at 900 and 1100 °C, respectively. The reduction of grain size down to nano-scale was not sufficient enough to increase the fracture toughness of trialuminide. Fracture toughness was also remained relatively constant and showed no significant dependence on Mn concentration. Microhardness was generally increased with increasing Mn concentration and decreased with increasing heat treatment temperatures due to the grain size effects. The formation of L1 2 phase played a major role in increased fracture toughness and (Al+0.08 Mn) 3 Ti showed the highest fracture toughness of 4.12 MPa m 1/2 with only L1 2 phase formation.

The low-temperature cyclic oxidation resistance of MoSi 2 /19.3 vol% SiC nanocomposite coating formed on a Mo substrate in air at 500°C was investigated and compared with that of the monolithic MoSi 2 coating using field emission-scanning electron microscopy (SEM) and crosssectional transmission electron microscopy (XTEM). The nanocomposite coating was produced by a prior carburizing process followed by chemical vapor deposition of Si on a Mo substrate. While the accelerated oxidation behavior was observed for the monolithic MoSi 2 coating after the incubation time of about 454 cycles, no pest oxidation was observed in the nanocomposite coating. The excellent low-temperature cyclic oxidation resistance of nanocomposite coating resulted from the deceleration of further inward diffusion of oxygen by formation of relatively dense SiO 2 and Mo 9 O 2 6 composite oxide scale through the preferential oxidation of SiC particles followed by oxidation of MoSi 2 phase.

In this paper, a modified Smith predictor in the presence of input and output disturbances as well as modeling uncertainty is investigated. The modified Smith predictor includes the feedforward Smith predictor and the compensator that approximates the inverse of time-delay. Assuming a multiplicative uncertainty, a robust stability criterion and a compensator design criterion are derived. The modified Smith predictor is applied to a reclaimer, which is used in the raw yard of a steel plant and has a large output time-delay. The system identification method is used to find out a nominal model. The uncertainty bound is quantified in the frequency domain through an uncertainty quantification method. Simulation results are provided.

The formation process of MoSi2/β-SiC composite coating by chemical vapor deposition of Si on the Mo2C layer formed in advance on a Mo substrate by a carburizing process was investigated using optical microscopy, field-emission scanning electron microscopy cross-sectional transmission electron microscopy and X-ray diffraction. The composite coating was composed of equiaxed MoSi2 grains with average size of 300 nm and the β-SiC particles with average size of 92 nm, which were mostly located at the grain boundaries of MoSi2. The morphology of β-SiC particles was oblate-spheroidal shape and volume percentage was approximately 19.3%. The number of cracks in the composite coating was smaller than that for the monolithic MoSi2 coating by the reduced mismatch of thermal expansion coefficient with the Mo substrate. The formation mechanism of MoSi2/β-SiC composite coating was suggested on the basis of microstructure observation.

A WSi2/(19.3–32.9) vol.% β-SiC nanocomposite coating was formed by chemical vapor deposition of Si on the W-carbide layers. The nanocomposite coating consisted of the equiaxed WSi2 grains with the average size of 88–153 nm and the β-SiC particles with the average size of 37–65 nm, which were mostly located at the grain boundaries of WSi2.

The kinetics of chemical vapor deposition (CVD) of Si on the Ni substrate at deposition temperatures between 850 and 1050 °C using hot-wall reactor and SiCl 4 –H 2 gas mixture was investigated. The deposition rate of Si on the Ni substrate obeyed a linear rate law. The activation energy for Si deposition was approximately 117 kJ/mol at low temperatures, indicating that the rate-limiting step for deposition of Si was the chemical reaction step to deposit Si on the surface of substrate. At high temperatures above 975 °C, activation energy was approximately 29 kJ/mol, indicating that that was the mass transport step of reactant gas species through a gas boundary layer from the main gas stream to the surface of Ni substrate. Under CVD conditions of Si limited by the mass transport step, there was a limit in the increase of the Cl/H input ratio to increase the deposition rate of Si on Ni substrate due to etching effect of Si.

Under chemical vapor deposition (CVD) conditions of Si on Mo substrate limited by mass transport of reactant gas species through a gas boundary layer, the effect of the Cl/H input ratio on the growth rate of MoSi 2 coating at 1200 °C was investigated using a horizontal hot-wall reactor and SiCl 4 –H 2 gas mixtures. The growth kinetic of the MoSi 2 coating obeyed a parabolic rate law irrespective of Cl/H input ratios. The growth rate of MoSi 2 coating initially increased with increasing Cl/H input ratio until the maximum growth rate was reached, and then decreased inversely proportional to the Cl/H input ratio at higher Cl/H input ratio. This suggests that there is a limit to the increase in growth rate for MoSi 2 coating due to the etching effect of Si with respect to the input ratio of Cl/H. The etching effect of the Cl/H input ratio on the growth rate of the MoSi 2 coating was explained by thermodynamic calculations based on the variation of silicon activity on the surface of the MoSi 2 coating. The mass balance between the Si flux supplied by the mass transport step and that consumed by solid-state diffusion to form MoSi 2 coating was considered to be responsible for the activity of silicon.

The microstructures and growth kinetics of the Mo 5 Si 3 and Mo 3 Si layers in the MoSi 2 /Mo diffusion couple was investigated using optical microscopy, field-emission scanning electron microscopy, electron probe microanalyzer, and cross-sectional transmission electron microscopy. The MoSi 2 /Mo diffusion couple was made by chemical vapor deposition CVD of Si on a Mo substrate at 1100 °C and annealed at temperatures between 1250 and 1600 °C in an Ar atmosphere. Simultaneous parabolic growth of the Mo 5 Si 3 and Mo 3 Si layers was observed at the early annealing stage of the MoSi 2 /Mo diffusion couple. From the marker experiments using ZrO 2 particles, the growth mechanism of the Mo 5 Si 3 and Mo 3 Si layers and the dominant diffusion element in each phase were revealed. The difference in the growth rates of Mo 3 Si layer between the MoSi 2 /Mo diffusion couple and the Mo 5 Si 3 /Mo diffusion couple was explained by a multiple layer growth model.