Pressureless Sintering and Reaction Mechanisms of Ti3SiC2 Ceramics

Easy sinterable Ti₃SiC₂ powder was synthesized from a powder mixture with a molar ratio of 1.0 Ti, 0.3 Al, 1.2 Si, and 2.0 TiC by heating at 1200°C in the flowing Ar. Here, the Al powder acts as a deoxidation agent and provides a liquid phase for the reaction. The powder compacts subjected to pressureless sintering at 1300°C in Ar had a relative density up to 99%. The results of chemical analysis and the measured lattice constant suggest that the Al–Si liquid phase was formed at approximately 1200°C and that liquid‐phase sintering was promoted by the 0.1 molar ratio of Al and the 0.2 molar ratio of Si remaining in excess. The three‐point bending strength, fracture toughness, and electrical resistivity of the sintered samples were 380 MPa, 4.1 MPa m^1/2, and 0.34μΩm, respectively.     

Efficient phenol removal of wastewater from phenolic resin plants using crosslinked cyclodextrin particles

Removal of phenolic compounds from a raw industrial wastewater from phenolic resin processing, of which the components are phenol (8.9 wt%), m‐ and p‐cresols (0.33 wt%), and xylenols (0.044 wt%), was carried out by using crosslinked cyclodextrin particles as a sorbent. A series of sorbents was prepared by varying the combination of cyclodextrin (CyD), β‐CyD, γ‐CyD, Mix‐CyD (α‐CyD:β‐CyD:γ‐CyD:dextrin = 30:10:10:50 wt/wt), the crosslinker, hexamethylene diisocyanate (HDI) or toluene‐2,6‐diisocyanate, and their molar ratio in the reaction batch. The removal of the phenolic compounds from raw industrial wastewater was an instantaneous process and was completed within about 5 min. The best removal efficiency was obtained by the crosslinked β‐CyD with HDI in a 1:8 molar ratio or the crosslinked Mix‐CyD with HDI, also in a 1:8 molar ratio. The prepared sorbents were efficiently regenerated by elution of the adsorbed phenols from the crosslinked polymers with methanol. Copyright © 2006 Society of Chemical Industry     

The effect of manganese on the precipitation of Mg17Al12 phase in magnesium alloy AZ 91

Non-uniform continuous precipitation of the β-phase is known to occur within the solution-treated grains of AZ91 alloys during aging. In the present study, the segregation profiles of solute elements in the as-cast, solution heat-treated, and aged specimens of AZ91E were examined by electron probe micro analysis. The results were correlated with optical and SEM observations of the microstructures. It was found that the dendrite cores of the cast structure were richer in manganese concentration and these manganese-rich regions remained unchanged even after solution heat-treatment for 24 h at 410 °C, while the segregated aluminum and zinc in the interdendritic regions of the cast structure diffused homogeneously into the matrix grains. It was also found that the regions of grains that were richer in manganese were a source of preferential nucleation for β-precipitates. Thus, the cause of the non-uniform distribution of β-phase precipitates during aging is attributed to the solute segregation of manganese during solidification.     

Relation of serum total cholesterol, serum triglycerides and fasting plasma glucose to colorectal carcinoma in situ

BACKGROUND: No one has previously examined the relation of serum total cholesterol, serum triglycerides and fasting plasma glucose to colorectal carcinoma in situ. METHODS: A case-control study was performed with 129 cases of colorectal carcinoma in situ and 258 matched controls among examinees undergoing a health check-up in Tokyo from January 1991 to March 1993. RESULTS: There was a significant, positive association between serum total cholesterol levels and the risk of colorectal carcinoma in situ after adjustment for age, sex, body mass index, smoking status and alcohol consumption. Serum triglyceride levels were significantly and positively associated with colorectal carcinoma in situ risk regardless of adjustment for the above covariates. Although there was no clear relation between colorectal carcinoma in situ and fasting plasma glucose levels, a modest increase of colorectal carcinoma in situ risk was observed in the highest category (> or =116 mg/dl) of fasting plasma glucose levels. CONCLUSIONS: The findings suggest a positive association between serum total cholesterol levels and the risk of colorectal cancer, rather than an inverse relation. The strong association with serum triglyceride levels and the weak association with fasting plasma glucose levels support the hypothesis that hyperinsulinaemia may play an important role in colorectal carcinogenesis.     

Results of radiation therapy for limited small-cell lung cancer

Results of radiotherapy were reviewed in 68 patients with limited small-cell lung cancer from the aspect of local control. Thirty-one patients achieved CR (46%), while the other 31 remained at PR. The 1-, 2-, 3-, and 5-year cumulative survival rates were 57%, 28%, 21%, and 16%, respectively, for 15 months in MST. Thirty-six patients developed local recurrence (53%) and 46 had distant metastasis (68%). The thirty-one patients with CR had a 43% 2-year-survival rate and 23 months in MST. The remaining 37 patients (PR + NC) had respective figures of 13% and 13 months (p < 0.025). There was no statistically significant difference between radiation dose and local thoracic failure among the patients. Of the 31 patients with CR, 28 had achieved CR at 45Gy (17 received 55Gy or more, and 11 less than 55Gy). In the former, the local control rate, 2-year-survival and MST were 94%, 53% and 44 months, while in the latter these were 45%, 27% and 17 months, respectively. Thirty-five patients were irradiated by the shrinking field technique according to tumor reduction; however, this technique did not influence the treatment results. To obtain better results, it is first necessary to achieve CR at initial chemo-radiotherapy. As to irradiation, randomized trials between 50Gy and 60Gy would require patients with CR at 45Gy.     

Estimation of fatigue crack propagation life of steel plates and of structural member model of ship hull

The authors carried out experimental and analytical investigation for the purpose of finding out a method of estimating the fatigue crack propagation life of large flat steel plate and of ship hull structure model quantitatively.We theoretically derived a formula indicating that fatigue crack propagation rate is in proportion to the $\text{m-}\text{th}$ power of the plastic displacement of the tip of a crack based on a B.C.S. dislocation model. The crack propagation rate is proportional to $\text{2m-}\text{th}$ power of stress intensity factor in the case stress is small.We proved experimentally that this relation holds generally, from fatigue crack propagation tests for flat plates with a center notch (mild steel, high tensile strength steel), large flat plate with an edge notch and ship hull corner model (mild steel), and from the $\text{K-}\text{value}$ calculation by the finite element method for these specimens. The fatigue crack propagation life is obtained by integrating the reciprocal number of crack propagation rate from the initial crack length to the final crack length. The life calculated agreed well with the one observed. But for the two stress level test, the life calculated was smaller than the experimental value due to slackened progress of crack. We also stated the general characteristics of the rate curve.