► Al–SiC surface composite was fabricated by ball collisions at room temperature. ► Structural formation was associated with strain accumulation induced by ball impacts over time. ► Composite ...formation was the result of mechanical mixing of the plasticized Al and SiC. ► Initial rolling texture of the Al plate was completely destroyed by 10min of ball collisions. ► Hardness of the composite became almost three times that of the initial Al plate.
An Al–SiC surface composite was fabricated on an Al surface precoated with SiC particles by ball collisions at room temperature in an ambient atmosphere. The formation of the composite was investigated at various treatment intervals between 5 and 30min. The structural formation was affected by the treatment time, which was associated with the accumulation of strains introduced by ball collisions. In the strained zone, Al became plasticized and flowed. The Al plastic flow trapped, occluded and transported the SiC particles. Ball collisions refined the coarse grains of the initial Al plate and the SiC particles. The initial rolling texture of the Al plate, consisting of {112}〈111〉 and {110}〈112〉 orientations, was completely destroyed by 10min of ball collisions. After 15-min treatment, the composite structure consisted of three phases: ultrafine-grained Al matrix, coarse SiC reinforcement and nanocrystalline Al–SiC composite interlayers. The hardness of the as-fabricated composite was increased almost threefold compared to that of the initial Al plate.
Nanostructured multicomponent Mo coatings were fabricated on Ti and Al substrates by ball impact cladding at room temperature in an ambient atmosphere. The process involved subjecting the substrate ...and Mo foil fixed at the top of a vibration chamber to high-energy collisions with balls. The coating formation was the result of a simultaneous process of mechanically induced plastic flow, nanocrystallization, and interdiffusion caused by the ball collisions. Plastic deformation refined the grains at the Mo foil/substrate interface to the nanometre scale. The size of nanocrystalline grains in the Mo coatings ranged between 2nm and 10nm. The ball collisions caused atomic level intermixing of different elements, introduced into the surface from the steel balls used for milling, and solid solubility improved remarkably. The hardness of the Mo coatings on the Al and Ti substrates was 552 and 1010 HV, respectively. The initial hardness of the Mo foil was 287 HV. The high hardness of the Mo claddings was attributed to the fine grain structure, formation of supersaturated solid solutions, and high residual compressive stresses.
Mechanical milling and ultrasonic mechanical coating and armouring (UMCA) were used for depositing of TiN coatings on different substrates. A powder and balls were placed in a vibration chamber. The ...substrate can be placed in the chamber with the powder or it can be fixed to the top of the chamber. During a mechano-activation process, the substrate surface is subjected to high-energy ball impacts. Powder particles trapped between the ball and surface cold weld to the surface. TiN coatings can be formed in a short time at room temperature under ambient atmosphere. The thickness, roughness and structure were found to depend on substrate hardness, milling intensity and size of initial TiN particles. Coatings having thicknesses up to 18
μm were fabricated through mechanical milling when the 7
mm balls and 50
nm particles were used. UMCA could be used to form smooth uniform coatings (thickness: ∼5
μm) after treatment for 6
min on 10
cm plates.
Summary
Background
The Kv1.3 voltage‐gated potassium channel is selectively upregulated upon activation in effector memory T (TEM) cells in inflamed tissue, and plays an important role in maintenance ...of T‐cell activation. Although Kv1.3 blockers have been shown to ameliorate allergic contact dermatitis (ACD) in a rat model, it remains unknown whether the effect of Kv1.3 blockers on ACD is mediated by suppressing TEM cell function and/or whether naive T‐cells or central memory T (TCM) cells are influenced.
Aim
To analyse the detailed mechanism of Kv1.3 blockers in a rat model of ACD.
Methods
We examined the effects of a Kv1.3 blocker on inflammation and production of the effector cytokine interferon (IFN)‐γ in inflamed tissue in rat ACD. Single‐cell suspensions were isolated from inflamed rat ears (TEM cells), and regional lymph nodes (naive T/TCM cells), and the effect of Kv1.3 blockers on anti‐CD3‐stimulated IFN‐γ production in vitro was measured.
Results
The Kv1.3 blocker significantly suppressed ear inflammation and IFN‐γ production at the protein level in vivo. It also suppressed in vitro IFN‐γ production from TEM cells from inflamed tissues, but did not suppress the function of naive T/TCM cells from lymph nodes.
Conclusions
We found that the Kv1.3 blocker ameliorated ACD by inhibiting TEM cell functions only, thus Kv1.3 blockers could be a potentially selective therapeutic agent for TEM cell‐mediated inflammatory skin diseases without producing harmful side‐effects.
Click here for the corresponding questions to this CME article.
The objectives of this work are to understand the details of the mechanism of dioxin formation in the part of a sintering bed termed the dry zone, and to obtain ideas on how to prevent their ...formation. Sinter mixtures of various composition types were heated in a packed bed reactor, and dioxins in the outlet gas and in the sinter mixture residue were measured. The dioxin formation potential of a simple sinter mixture composed of iron ore, coke and limestone was markedly lower than that of fly ash from a municipal solid waste incinerator (MSWI). In consideration of this result, a series of experiments were conducted using a sinter mixture impregnated with CuCl
2. Experimental results showed that dioxin formation was temperature-dependent in the range of 300–550 °C, with the maximum observed at around 300 °C, which was quite similar to that of fly ash from the MSWI. The homologue distribution of PCDD/Fs in gas and solid reflected the possible difference in carbonaceous materials in coke and activated coke. Gaseous hydrogen chloride acted as a chlorinating reagent for dioxin formation.
Ball impact cladding is a process in which solid-state welding of a foil and substrate is carried out in a vibration mill. The principle of the process is that a substrate and foil are fixed at the ...top of a vibration chamber. During the subsequent mechano-activation process, the materials are subjected to high-energy collision with balls. As a ball collides with the surface, the foil is cold welded to the substrate. This is a simple and effective method for joining materials, and it also results in the formation of nanostructures. For example, the welding of Cu and Al foils to Al, Ti, and steel substrates has been attempted. Diffusion and plastic flow of materials under ball collisions were the main joining mechanisms contributing to welding. Under the ball collisions a nanograin structure was formed across the foil and at the interface of the substrates. The cladding foils had a good adhesion to substrates.
A mechanical milling method was used for the deposition of TiN coatings. The principle of this method is that a substrate and powder were placed along with balls into the vibration chamber that was ...vibrated by a mechano-reactor. During mechanical milling process, the substrate surface was impacted by a large number of flying balls. The TiN particles trapped in between the balls and the substrate became cold welded to the surface. The repeated substrate-to-ball collisions forged TiN particles into a coating on the substrate surface. The process allowed the thick TiN coatings to be produced at room temperature in an ambient atmosphere. TEM study of the as-fabricated coatings was carried out. The coating formation depended on the size of the initial TiN particles. The 50-nm TiN nanoparticles were more easily cold welded than 1.5-μm microparticles. The nanoparticles had a tendency to consolidate and densify into the bulk material under the applied compressive loading. The TiN particles better consolidated and densified on the hard Ti surface than on the soft Al one.
By means of the mechanical alloying (MA) method, the Ti
+
Al coatings were deposited on Ti alloy substrates. The structural formation of the Ti–Al coatings as a function of the milling time was ...studied. The thickness of coatings and their structure depended on the milling duration. At initial stage Al covered the Ti substrate. Then Ti particles were embedded in the Al matrix. Gradually the composite coating was formed. Greater plastic deformation led to the formation of the layered coating structure. Prolonged milling resulted in refinement of the particles into the nanometer scale near surface region of the Ti–Al coating.
High-adhesion LaPO4 coatings were fabricated on steel substrates at temperatures of 150-400 deg C after a 10 min treatment using an ultrasonic-based coating process. The principle underlying this ...process is the collision of ultrasonically accelerated hard balls with the substrate surface that is covered by loosely adhered LaPO4 particles. The repeated substrate-to-ball collisions flatten the precoated LaPO4 particles, bond them together and cold weld them to the substrate. The coating thickness, roughness and structure were found to depend on the substrate temperature. The LaPO4 coatings produced at temperatures ranging from 150 to 250 deg C exhibited a granular and porous structure. The treatment at temperatures higher than 300 deg C enabled the production of rather dense coatings.
ABSTRACT
We present an improved measurement of the Hubble constant (H0) using the ‘inverse distance ladder’ method, which adds the information from 207 Type Ia supernovae (SNe Ia) from the Dark ...Energy Survey (DES) at redshift 0.018 < z < 0.85 to existing distance measurements of 122 low-redshift (z < 0.07) SNe Ia (Low-z) and measurements of Baryon Acoustic Oscillations (BAOs). Whereas traditional measurements of H0 with SNe Ia use a distance ladder of parallax and Cepheid variable stars, the inverse distance ladder relies on absolute distance measurements from the BAOs to calibrate the intrinsic magnitude of the SNe Ia. We find H0 = 67.8 ± 1.3 km s−1 Mpc−1 (statistical and systematic uncertainties, 68 per cent confidence). Our measurement makes minimal assumptions about the underlying cosmological model, and our analysis was blinded to reduce confirmation bias. We examine possible systematic uncertainties and all are below the statistical uncertainties. Our H0 value is consistent with estimates derived from the Cosmic Microwave Background assuming a ΛCDM universe.
PDF