Prediction of high-cycle fatigue life reliability of aluminum cast alloy from statistical characteristics of defects at meso-scale

In this paper, a growth rate law of a small fatigue crack of an arbitrary metal and a method for predicting a size distribution of spheroidal defects cut by a specimen are proposed. And then, by combining the crack growth rate law and the prediction method for the surface defect size distribution, a method for predicting a high-cycle fatigue life reliability of a metal with defects is proposed. Rotating bending fatigue tests of plain specimens with/without a small blind hole (0.3 mm in diameter, 0.15 mm in depth) are carried out on an aluminum cast alloy JIS AC4B-T6 with eutectic Si, Fe compounds and porosities. By comparing analyzed results with experimental ones, the validity of the present method is examined.     

New Attractants for Males of the Solanaceous Fruit Fly <Emphasis Type="Italic">Bactrocera latifrons</Emphasis>

α-Ionone, α-ionol, and their mixtures with phenolic volatiles act as potential male lures for the solanaceous fruit fly Bactrocera latifrons (Hendel). However, the attractiveness of these compounds is not as strong as that of other well-known tephritid male lures, such as methyl eugenol for Bactrocera dorsalis. Isophorone and isophorol, which have a partial skeletal structure of α-ionone/α-ionol (i.e., trimethylcyclohexene), were attractive to B. latifrons males, and their mixtures with α-ionol exhibited stronger activity than any of the individual compounds. We also tested 3-oxo-α-ionone, 3-oxo-α-ionol, 3-hydroxy-α-ionone, and 3-hydroxy-α-ionol, hybrid compounds between isophorone/isophorol and α-ionone/α-ionol. 3-Oxo-α-ionone and 3-oxo-α-ionol were active both as attractants and phagostimulants for males. The results suggest that the introduction of an oxygen atom at the 3-position of the α-ionone/α-ionol molecule optimizes the specific chemosensory responses in B. latifrons males.     

Polymerization of alpha-hydroxy acids by ribosomes

Over 30 years ago, Fahnestock and Rich reported intriguing data showing the capability of the ribosome to polymerize phenyllactic acid. Although the polymerization was initiated and terminated randomly on polyuridic acids, the given data convincingly suggested that the generated polymer was composed of an approximately 7:3 mixture of phenyllactic acid and phenylalanine. Despite the fact that Fahnestock's conclusion was very likely correct, there have been no reports to follow up the ribosome-catalyzed polymerization of alpha-hydroxy acids until very recently. At the end of 2007, we reported messenger RNA (mRNA)-directed polyester synthesis by using the new emerging method of genetic-code reprogramming in which alpha-hydroxy acids with various kinds of side-chains are assigned to arbitrarily chosen codons. In this work, we have achieved the ribosomal synthesis of polyesters with the sequence composition and length in a fully controlled manner according to the sequence of mRNA. This Concept article describes the background of the method development and its application to the synthesis of polyesters.     

Differences of drivers' reaction times according to age and mental workload

This study was designed to examine differences in reaction times of drivers of various age groups and to assess the influence of mental workload on reaction times. Experiments were performed on a simulated street and under other conditions to identify drivers with long reaction times and drivers whose reaction times are affected strongly by mental workloads while driving on a public road. Reaction times after hearing a buzzer were measured under five conditions: (1) sitting in a stationary vehicle, (2) executing mental calculations in a stationary vehicle, (3) driving on a simulated street, (4) executing mental calculations while driving on a simulated street, and (5) driving on a public road. Subjects were 10 drivers each of three age groups. Each experiment was performed by these subjects under the five conditions. Results showed that mental calculations increased the average reaction time for each age group. Mental calculations increased differences among age groups and individuals, and increased differences in respective drivers' individual performance. Mental calculations influenced elderly drivers' reaction times remarkably. Results also demonstrated that an experiment on a simulated street identified drivers who showed long reaction times on a public road.     

Layer-by-layer self-assembled mutilayer films of gold nanoparticles for surface-assisted laser desorption/ionization mass spectrometry

Layer-by-layer (LBL) self-assembled multilayer films of gold nanoparticles (AuNPs) on a silicon wafer were demonstrated to be promising substrates for surface-assisted laser desorption/ionization (SALDI) mass spectrometry (MS) of peptides and environmental pollutants for the first time. LBL multilayer films, (AuNPs/PAHC)n, consisting of alternating layers of ammonium citrate capped AuNPs and poly(allylamine hydrochloride) (PAHC) were prepared on a silicon surface. Silicon plates with aggregated AuNPs were more suitable than those with dispersed AuNPs for the SALDI-MS of peptides. The number of particle layers had a significant effect on the laser desorption/ionization of angiotensin I; the peak intensity of the peptide (molecular ion amount) increased with an increase in the number of layers of AuNPs. As a result, the (AuNPs/PAHC)5 multilayer films increased the sensitivity of the angiotensin I to subfemtomoles and raised the useful analyte mass range, thus making it possible to detect small proteins (a 12 kDa cytochrome c). The signal enhancement when using (AuNPs/PAHC)5 may be due to (i) the high absorption of the UV laser light at 337 nm by the AuNP layers, (ii) the low thermal conductivity due to the AuNPs being covered with a thin monolayer of PAHC, and (iii) the increase in the surface roughness (approximately 100 nm) with the number of AuNP layers. Thus, laser-induced rapid high heating of AuNPs for effective desorption/ionization of peptides is possible. In addition, it was found that (AuNPs/PAHC)5 could be used to extract environmental pollutants (pyrene and dimethyldistearylammonium chloride) from very dilute aqueous solutions with concentrations less than 10(-10) mg/mL, and the analytes trapped in the LBL film could be identified by introducing the film directly into the SALDI mass spectrometer without needing to elute the analytes out of the film.     

Accurate phase-added stereogram to improve the coherent stereogram

We propose an "accurate" phase-added stereogram, which can be defined as an improved phase-added stereogram. Generally, the macroblock size transformed by the fast Fourier transform is the same as the segmentation size of the phase-added stereogram. However, the proposed method uses a lager macroblock size than does the conventional method to reduce quantization error in discrete spatial frequencies in the spatial frequency domain. Therefore, even when the fast Fourier transform is used for calculation, the quality of the reconstructed image can be improved to be as clear as the Fresnel hologram.     

Reflections on identifying the real ΔKeffective in the threshold region and beyond

The use of the crack tip stress intensity factor, K, has survived almost 50 years as the key parameter correlating fatigue crack growth. As time past the range of the stress intensity, ΔK, was recognized as causing alternating plasticity at the crack tip. The threshold level for ΔK was discovered. Further, the occurrence of crack closure was noted which affected the ΔK for different load ratios, R of cyclic loading. The ASTM method of counting the linear part of the load displacement for determining ΔK_open was found to understate the ΔK_effective, which correlates data for different load ratios. One approach to adjust for this problem is the “Partial Closure Model”, where the closure only occurs away from the crack tip. Here it will be discussed that such a model leads to a universal growth law. Moreover, this law shows application in estimating the order of magnitude of crack growth life (<10⁷ cycles) for example with very high cycle fatigue (>10⁹ cycles). Some advances in this application will also be cited.     

Microstructural evolution and mechanical property in dual two-phase intermetallic alloys composed of geometrically close-packed Ni3 X (X: Al and V) containing Nb

Dual two-phase intermetallic alloys composed of geometrically close-packed (GCP) structures of Ni₃Al (L1₂) and Ni₃V (D0₂₂) containing Nb were investigated in terms of microstructural evolution during low-temperature annealing (aging) and the related mechanical properties. The eutectoid region, i.e. the prior Al phase (Ni solid solution) is composed of the lamellar-like structure consisting of Ni₃Al (L1₂) and Ni₃V (D0₂₂) even at an early aging stage, and then coarsen with increasing aging time. The lamellar-like structure tend to align along direction and on {001} plane in the prior A1 phase (or the L1₂ phase). In a wide range of temperature, the dual two-phase intermetallic alloys showed high yield and tensile strength, and also reasonable tensile ductility, accompanied with ductile fracture mode. The observed mechanical properties were less sensitive to the microstructural evolution during low-temperature annealing (aging), meaning that the present dual two-phase intermetallic alloy is promising for a new type of high-temperature structural material.     

Optical characterization of vanadium-titanium oxide films

Composite films of titanium and vanadium oxides (TVO) with various compositional ratios were prepared by sputtering deposition. The optical properties, crystalline structure and film morphology were investigated as a function of the composition. The results of thermochromism and X-ray diffraction suggest that the TVO films at any compositional ratios form substitutional solid solution of Ti and V, that is, Ti_xV_1−xO₂, where 0 ≤ x ≤ 1. Dielectric constants of the TVO films at any compositions were consistently determined at photon energies between 0.75 to 3 eV by employing the Lorentz-oscillator formula. With wide variation in x, the dielectric constants at visible and near-infrared wavelengths monotonically decrease down to the values of TiO₂, which suggests that dielectric constants of the TVO film can be precisely controlled by adjusting rf power in co-sputtering deposition.