Formation and growth morphology of oxidation-induced ferrite layer in Fe-Mn-Al-Cr-C alloys

Three austenitic Fe-31 Mn-9Al-xCr-0.87C alloys (x=0, 3 and 6) have been oxidized in dry air at 800 to 1100 ° C. An oxidation-induced ferrite layer is observed between the oxide layer and the austenite matrix. The ferrite layer is formed due to the selective oxidation of manganese. Qualitative and quantitative electron microscopic techniques are employed to investigate the morphological development and elemental redistribution in the alloy system. The mechanism of the formation and growth of the ferrite layer and the diffusion path of the carbon due to austenitic decomposition are explored.     

Gene structure of the human MET proto-oncogene

By direct sequencing of cosmids using primers designed from the known cDNA sequence, we identified 19 exons in the human MET proto-oncogene, and sequenced the corresponding 5' and 3' exon-intron junctions. By homology search in the database of the Washington University Genome Sequence Center (GSC), we identified one additional exon. These 20 exons, together with a previously reported exon, bring the total exon number of MET to 21. Oligonucleotide primers were designed to amplify each exon and adjacent intronic sequences to permit examination of each exon for mutations. By restriction mapping, we assembled a 110 kb genomic contig that covered almost the entire MET proto-oncogene. This information is relevant for the screening of recently reported mutations of the MET gene which cause hereditary papillary renal carcinomas and for the search for additional mutations of the same gene which may play a role in the pathogenesis of common human carcinomas including carcinomas of the breast, ovary and pancreas.     

Design of high-power, high-efficiency 60-GHz MMICs using animproved nonlinear PHEMT model

This work describes the design and nonlinear modeling of two V-band monolithic microwave integrated circuit (MMIC) power amplifiers using a nonlinear high electron mobility transistor (HEMT) model developed specifically for very short gate length pseudomorphic HEMTs (PHEMTs). Both circuits advance the state-of-the-art of V-band power MMIC performance. The first, a single-ended design, produced 293 mW of output power with a record 26% power-added efficiency (PAE) and 9.9 dB of power gain at 62.5 GHz when measured on-wafer. The second MMIC, a balanced design with on-chip input and output Lange couplers for power combining, generated a record 564 mW of output power (27.5 dBm) with 21% PAE and 9.8 dB power gain. The MMIC's are passivated, thinned to 2 mils, and down-biased to 4.5 V for high reliability space applications. These excellent first-pass MMIC results are attributed to the use of an optimized 0.1-/μm PHEMT cell structure and a design based on millimeter-wave on-wafer device characterization, together with a new and very accurate large signal analytical FET model developed for 0.1-/μm PHEMTs     

Growth and invasion of differentiated thyroid gland carcinoma: importance of signal transduction

To define the long-term dental sequelae of therapy for childhood rhabdomyosarcoma of the head and neck, and to identify factors in their development, we retrospectively reviewed the serial panoramic radiographs and clinical records of 22 survivors of head or neck rhabdomyosarcoma who had been followed for at least 5 years. Patients were divided into four groups based upon age at the time of therapy and three groups based upon radiation doses. All patients had received similar multiagent chemotherapy. Dental sequelae of oncotherapy occurred in over half of the long-term survivors of head and neck rhabdomyosarcoma. The abnormalities comprised root stunting in 54%, microdontia in 23%, and hypodontia in 50% of patients; 36% had multiple abnormalities. Microdontia and multiple abnormalities were more prevalent in patients treated at the earliest age, and abnormalities tended to be more prevalent with increasing doses of radiation. Five patients (23%) developed severe cosmetic and/or functional sequelae necessitating surgical and/or orthodontic intervention. The high frequency of dental sequelae we observed suggests that meticulous long-term dental and radiographic follow-up are needed. Early detection and treatment of the complications of therapy will expedite their correction and minimize morbidity.     

Germline mutations in the von Hippel-Lindau disease tumor suppressor gene: correlations with phenotype

The efficacy of nonreamed nailing as the treatment of choice of unstable blunt tibial diaphyseal fractures was studied. From March 1, 1990, through August 31, 1991, 72 patients with 74 fractures that required fixation were treated. One patient died and six were lost to follow-up, leaving 65 patients with 67 fractures. Follow-up averaged 21 months (range 5-43). Fisher's exact and logistic regression analyses were used to compare grades of open fractures, comminution as classified by Winquist, and dynamic and static nailings. The failure rates of 51 titanium and 16 stainless steel nails were compared. Times to union were compared by the log rank statistic method. The average time to union was 32 weeks with 26 (39%) additional operations required to achieve union; 13 dynamizations (12 successful), 12 exchange nailings (11 successful), and one plate and bone graft. The rate of reconstructive procedures to achieve union was a more sensitive indicator of difficulties achieving union than was time to union. Reoperation rates were 33% for closed or grade I and II fractures compared with 46% for grade III fractures (NS). Among closed grade I and II static versus dynamic nailing, times to union were 36 versus 25 weeks (p < 0.01), and the reoperation rates were 44% versus 13% (p < 0.04). Winquist I and II fractures required a 24% reoperation rate versus 53% for grade III and IV and segmental fractures (p < 0.01). Static locked fractures required a 48% reoperation rate versus 12% for dynamic locked fractures (p < 0.01). A logistic regression analysis demonstrated that locking mode was the most important factor in determining reoperation rates. Fifteen additional reoperations for infection, broken or painful implants, or to remodel bones that united with an incomplete circumference of cortex were performed. With an additional 12 elective nail removals, the total reoperations numbered 53 (79%). Titanium alloy nails had a 2% failure rate versus 25% for stainless steel nails (p < 0.01). Two of 28 (7%) grade III fractures became infected. All fractures united within 10 degrees of normal alignment and 1 cm of length. Nine (13%) united with an incomplete cortical circumference, refractory to dynamization and full weight bearing. Thirteen of the 58 (22%) fractures available for an evaluation of ankle motion were symptomatic, with < 10 degrees of dorsiflexion.(ABSTRACT TRUNCATED AT 400 WORDS)     

Napiergrass (Pennisetum purpureum S.) protects oxidative damage of biomolecules and modulates antioxidant enzyme activity

The effects of water extract of napiergrass (Pennisetum purpureum S.) (WEN) on oxidative damage of biomolecules and modulation of antioxidant enzyme activity were investigated. The results showed that WEN displayed marked free radical scavenging, reducing power, as well as ferrous ions chelating effects. WEN has a dose-dependent response for protective action on oxidation of phospholipid, deoxyribose and low-density lipoprotein (LDL) in the range of 0–0.5 mg/ml, indicating that WEN had in vitro protective action on oxidative damage of biomolecules. Oxidative stress induced by H₂O₂ significantly decreased the viability of BNL cells. However, addition of WEN in the medium protected cells from H₂O₂-induced cytotoxicity. Furthermore, treatment of cells with WEN in the range of 0–0.2 mg/ml displayed protective effect from H₂O₂ induced oxidation in a concentration dependent manner. With respect to the effect of WEN on antioxidant enzymes, the results showed the WEN at 0.2 mg/ml enhanced activities of glutathione peroxidase (GPX), glutathione reductase (GR), glutathione transferase (GST) and catalase (CAT) in BNL cells by 2.93-, 35.8-, 4.23-, and 2.78-fold, respectively, compared to the control; WEN increased the GSH content by 3.2-fold, implying that WEN may up-regulate the levels of GSH and antioxidant enzymes in BNL cells. WEN scavenged NO generated by a NO donor, sodium nitroprusside (SNP) and suppressed NO production in lipopolysaccharide (LPS)-activated macrophage RAW 264.7 cells. The determination of ascorbic acid and total anthocyanins as well as HPLC analysis revealed that ascorbic acid, rutin, epicatechin, anthocyanins, p-coumaric acid, quercetin and catechin were present in WEN, which function as in vitro antioxidants by virtue of their ability to scavenge ROS and RNS. Overall, the results obtained showed that WEN is rich in antioxidant components and they can serve as an excellent potential for use as a natural phytochemicals source.     

Thermal and electrical stability of ZnO varistors with glass additives

Glasses in the PbO-B₂O₃-Al₂O₃-BaO-CaO-SiO₂ system were employed as the dopant to ZnO varistors. The thermal stability of the varistor is enhanced with glass additives. The temperature coefficient of threshold field for the sample doped with 1 w/o glass (65 w/o PbO - 23 w/o B₂O₃ - 12 w/o SiO₂) is 1 × 10^-4/K as compared to 3.3 × 10^-3/K for that of the undoped sample. The change in the temperature dependence of the field-current density characteristics is more related to the barrier height change than the refractory behavior of the glass employed. Heat treatment is very effective in recovering the degraded samples by providing the activation energy for the diffusion of Zn interstitials. The experimental results can be explained with a Schottky barrier model.     

The use of X-ray line profile analysis in the tetragonal to monoclinic phase transformation of ball milled, as-sintered and thermally aged zirconia powders

The martensitic tetragonal to monoclinic (t → m) transformation in zirconia plays an important role in determining the mechanical properties and low temperature degradation of this ceramic. The analysis of X-ray data using the Warren–Averbach procedure can supply reliable information about crystallite size and microstrain under various conditions. The X-ray line profile analysis results can shed light on the martensitic transformation and the microstructural evolution of the t and m phases. The presence of m plates causing the formation of partially transformed t crystals reduces the mean size of the t crystals. The ball milling process also affects the mean size of the produced monoclinic crystals. The microstrain of the t and m phases can also be influenced by the ball milling and also by matrix constraints. Zirconia powders doped with low contents of CeO₂ exhibit an isothermal type t → m transformation during thermal annealing which affects the subsequent athermal transformation upon cooling and thus a decrease in the mean size of the m crystals is produced. This revised version was published online in November 2006 with corrections to the Cover Date.     

Antioxidative activity of three herbal water extracts

The antioxidative activity of water extracts of three herbs, including the flower of Chrysanthemum morifolium Ramat (FCMR), the calyx of Hibiscus sabdariffa L. (CHSL) and roasted seed of Hordeum vulgare L. (RSHVL), which are commonly called Hang Chu, Lo Shen and Chao Mai in Taiwan, respectively, were investigated. FCMR, CHSL and RSHVL showed marked antioxidative activity, not only in linoleic acid but also in liposome model systems, indicating that the three herbal water extracts may protect the cell from damage by lipid peroxidation. FCMR, CHSL and RSHVL possessed high contents of phenolic compounds and exhibited reducing power, revealing that these herbal extracts may containreductones. The water extracts of the three herbs also showed good hydrogen-donating abilities, indicating that they had effective activities as radical scavengers. No mutagenicity in the water extracts of the three herbs was found in Salmonella typhimurium TA98 and TA100, either with or without S9 mix.