In situ observations and crystallographic analysis of martensitic transformation in steel

The development of a martensitic structure in a low-carbon and low-alloy steel was characterized using in situ confocal laser microscopy, high-speed photography and crystallographic analysis, including the nature of variant selection. The initial stage of transformation involves the partitioning of the austenite grain into packets, after which the rate of transformation is gradual. The crystallographic orientation of the plates that form is not random, but involves selection determined by the relationship between the shape deformation direction and the free surface. The vicinity of austenite grain and twin boundaries, and martensite/austenite interfaces also affect variant selection.     

A Novel Chemoenzymatic Synthesis of Sulfated Type 2 Tumor‐Associated Carbohydrate Antigens by Transglycosylation of Sulfated Lewis X Oxazoline Catalyzed by Keratanase II

Sulfated type 2 carbohydrate chains are known tumor‐associated carbohydrate antigens (TACAs). Many reports on cancer vaccines employing TACAs as specific antigens have been published, but structurally specified sulfated TACAs have not been used because of the low natural abundance and difficulties in chemical synthesis. We demonstrate for the first time the synthesis of the sulfated type 2 TACAs with an l ‐fucose branch by keratanase‐II‐catalyzed transglycosylation of the sulfated Lewis X (Galβ(1→4)[Fucα(1→3)]GlcNAc(6‐OSO₃^?); su‐Le^x) oxazoline derivative. Two keratanase IIs (from Bacillus sp. Ks36 and Bacillus circulans KsT202) efficiently catalyzed the transglycosylation reaction of the su‐Le^x oxazoline derivative, thereby giving the su‐Le^x dimer as the main product in good yields. Structural analysis of the oligomers confirmed exclusive formation of the β(1→3) glycosidic bond.     

Risk assessment on processing facility of raw organic garbage

To investigate the cause of an explosion during disposal processing of raw garbage, the property of the raw garbage was primarily examined by a thermo gravimetry-differential thermal analyzer. With mutable oil concentration, the results showed variable onset temperatures of the exothermal reaction for the samples, for example, decreasing from 150 degrees C in the samples typically containing 10.9-14.1% oil to 114 degrees C when the oil content was raised to 40%. The disposal process was then simulated in a laboratory-scale facility being heated by hot air of 150 degrees C, which was blown into the bottom through nozzles. In the case of the dried garbage containing 14.1% oil, white smoke emitted after several hours, accompanying with an abrupt rise of the temperatures in particular at the bottom of the facility. The maximum temperature reached to 1070 degrees C. Meanwhile, gases, including flammable ones, whose amounts were CO2 approximately CO>H2>methane>ethane in order, were yielded. It indicated that smoldering developed from the zones near the hot air supply nozzle and propagated along the pathway of the imposed air. The continuously released gases possibly induced the transition of smoldering to flame or explosion after accumulating for hours.     

Deformation structure in ductile B2-type Zr–Co–Ni alloys with martensitic transformation

Microstructural evolution during tensile deformation in ternary Zr–Co–Ni alloys were investigated using transmission electron microscopy to clarify the mechanism of the enhancement of ductility observed in these alloys. In Zr₅₀Co₃₉Ni₁₁ alloy deformed at room temperature, lenticular martensite is observed in the B2 parent phase immediately after yielding, in addition to dislocations with the <100>_B2-type Burgers vector. The orientation relationship between the B2 parent phase and B33 martensite is determined to be [001]_B2//[100]_B33, (010)_B2//(021)_B33, and (110)_B2//(010)_B33. A midrib-like contrast is observed at the center of the lenticular martensite variant, and it is found to be a (021)_B33 twin. A trace analysis indicates that this contrast is nearly parallel to the {100}_B2, which may correspond to the habit plane of the martensite. The martensite variants grow into the B2 parent phase along the {100}_B2 with increasing tensile loading, and then grid-shaped martensite variants are formed at the failure of the specimen. The martensite would be dominantly formed and grow in the regions where the stress concentration occurs during tensile deformation. It is likely that the plastic deformation mainly proceeds in the untransformed B2 parent phase because this martensite is harder than the B2 parent phase. Consequently, the authors conclude that the remarkable enhancement of ductility can be attributed to a transformation-induced plasticity associated with deformation-induced martensite.     

Analysis of an optical resonator formed by a pair of specially shaped axicons

We propose a design for an optical resonator suited to using large-bore active media. The resonator consists of a pair of waxicons, so we call it a "wwaxicon optical resonator." The resonator is considered a conventional (solid) resonator surrounded by coaxial annular resonators. A numerical simulation of the resonator designed for use in a commercial CO2 laser is performed. It is found that parasitic oscillation modes can be suppressed by the use of an spatial-frequency filter. The resonator exhibits oscillation in the TEM*01 transverse mode and produces twice as much output power as a sevenfold multipass stable optical resonator.     

Risk evaluation on the basis of pressure rate measured by automatic pressure tracking adiabatic calorimeter

An automatic pressure tracking adiabatic calorimeter (APTAC) had been employed to obtain the thermokinetic and the vapor pressure data during runaway reactions. The APTAC is an adiabatic calorimeter with a large-scale sample mass and low thermal inertia, and is an extremely useful tool for assessing thermal hazards of reactive chemicals. The data obtained by the APTAC are important information for the design of the safe industrial process. The thermodynamics parameters and the gas production were discussed on the basis of the experimental data of various concentrations and weights of di-tert-butyl peroxide (DTBP)/toluene solution for the purpose of investigating the properties of the APTAC data. The thermal decomposition of DTBP was studied on the basis of the temperature data and the pressure data obtained by the APTAC. The activation energy and the frequency factor of DTBP are nearly constant and the same as the literature values in the concentrations between 20 and 60 wt.%. The pressure rise due to gas production is important data for designing the relief vent of a reactor. The time history of the gas production was investigated with various weights and concentrations. The total gas production index, which had the vapor pressure correction, was 1.0 in the decomposition of DTBP.     

The effect of diameter on the burning of crude oil pool fires

In order to understand the combustion characteristics of crude oil pool fires, an experimental study was carried out at the Fire Research Institute (FRI) large scale test facility. The radiative output, burning rate, and the concentrations of CO, CO₂, and smoke (above the flame tip) were measured during the burning of Arabian light crude oil, heptane, toluene, and kerosene floating on water. The effect of scale was studied by using steel pans ranging from 0.6 to 3 meters in diameter.Crude oil burned less rapidly and gave off less thermal radiation compared with heptane, but when water boiling, i.e., boilover, occurred, the burning rate increased by a factor of two or more. The intensity of boilover is related to pan diameter and initial fuel layer thickness.     

Mechanism of reduction of fretting fatigue limit caused by hydrogen gas in SUS304 austenitic stainless steel

The fretting fatigue strength of pre-strained SUS304 is reduced in hydrogen gas. The mechanism of the reduction is discussed. In hydrogen gas, local adhesion between contacting surfaces occurred and many small cracks were formed at the adhered spots. The major crack propagated from one of the small cracks. The roles of the adhesion in relation to the initiation and propagation of the small cracks were examined by a two-step environment test. When adhesion was prevented by an oxidized film, no failure of the specimen occurred. It can be presumed that the stress conditions were more severe in hydrogen gas than that in air due to local adhesion.