High-temperature oxidation of yttrium silicides

Current silicon melt-infiltrated (SMI) ceramic matrix composites (CMCs) are limited by the melting temperature of silicon (1414 °C) and the volatility of the thermally grown SiO₂ scale in high-temperature water vapor environments. Replacement of the melt-infiltrated (MI) silicon with a rare-earth silicide offers the potential to address both limitations of SMI CMCs. This study focuses on the ability of yttrium silicides to form yttrium silicates (phases with greater stability in high-temperature water vapor than SiO₂) in high-temperature oxidizing environments. Yttrium silicides with compositions of 41, 67 and 95 at.% Si–Y were fabricated using arc melting and oxidized in air at 1000 and 1200 °C for up to 24 h. Oxidation resulted in the rapid formation of a non-protective Y₂O₃ scale and rejected Si. Additional minor oxide phases of Y–Si–O, Y₂SiO₅, Y₂Si₂O₇ and SiO₂ were observed to form on and beneath the specimen surface. Characterization of the microstructural evolution with time and temperature helped elucidate the diffusion mechanisms that control oxide growth rates. Replacement of MI silicon with a MI yttrium silicide would significantly compromise the high-temperature performance of a CMC due to Y₂O₃ CTE mismatch with SiC, high oxygen permeability and the large volume change associated with its rapid subsurface formation. Results are utilized to examine the viability of other rare-earth silicides as MI materials for CMCs.     

MTPKM: Multipart Trust Based Public Key Management Technique to Reduce Security Vulnerability in Mobile Ad-Hoc Networks

Wireless Personal Communications - In distributed real time database management system (DRT-DBMS), QoS aware replication control strategy is necessary to ensure availability and to improve the...     

PSOBLAP: Particle Swarm Optimization-Based Bandwidth and Link Availability Prediction Algorithm for Multipath Routing in Mobile Ad Hoc Networks

Wireless Personal Communications - In mobile ad hoc network (MANET), optimal path identification is the main problem for implementing the Multipath routing technique. MANET desires an efficient...     

Design of a Buffer Enabled Ad hoc On-demand Multipath Distance Vector Routing Protocol for Improving Throughput in Mobile Ad hoc Networks

Wireless Personal Communications - The buffering in Mobile Ad hoc Networks (MANETs) will depend on end-to-end delay of every user’s information from the arrival time of the resource node...     

Enhanced Energy Proficient Encoding Algorithm for Reducing Medium Time in Wireless Networks

Wireless Personal Communications - Providing increased network coding gain is one of the optimum-based medium time problems in wireless networks. This problem is identified using non-linear...     

Decarbonization of electricity requires market-based demand flexibility

To effectively decarbonize the electric sector, utilities will need to address the growing load shape challenges driven by the variability of many renewable resources. Behind-the-meter solutions, such as energy efficiency, demand response, electrification and storage, will play an important role in grid stability, but only if they can deliver changes in demand that meet the time and locational needs of the grid. This article will discuss how smart meter interval data, combined with open source methods and software, provide transparent measurement of savings load shapes (resource curves) that enable the integration of demand flexibility into energy, capacity and carbon markets, and as a transmission and distribution resource. This allows utilities to procure demand flexibility in the same way they procure other resources by leveraging a price signal and pay-for-performance to drive innovation and attract private investment.     

Conjugated linoleic acid content of beef differs by feeding regime and muscle

The project objective was to determine the CLA content of three muscles (Longissimus lumborum, LD; Semimembranosus, SM; Triceps brachii, TB), in both raw and cooked states, in cattle finished on pasture or with grain supplements. Cattle were randomly assigned to one of four finishing regimens; pasture (n=11), pasture with grain supplement (n=11), pasture with grain supplement containing soyoil (n=12), and feedlot (n=12). In the raw state, TB had higher (P<0.05) CLA than LD or SM on a mg/g sample basis. Total CLA was higher (P<0.05) in the soyoil diet when compared to the other three feeding regimes on a mg/g sample basis and when expressed as mg/g fat in both raw and cooked analyses. Pasture inclusion produced higher levels (P<0.05) of total CLA than the feedlot diet on a mg/g fat basis for cooked samples while maintaining acceptable eating quality.     

Influence of modified atmospheric storage, lactic acid, and NaCl on survival of sublethally heat-injured Listeria monocytogenes

The effect of package atmosphere on survival of uninjured and sublethally heat-injured Listeria monocytogenes, inoculated onto tryptose phosphate agar containing 0.85% lactic acid and 2% NaCl (TPALAS) was investigated. Inoculated TPALAS plates were packaged in air, 100% N2 (N2), 30% CO2-70% N2 (CO2-N2), and vacuum and stored at 4 and 20 degrees C for up to 31 days. Recovery of L. monocytogenes from TPALAS was influenced by the injury status (i.e., injured and uninjured) of the inoculum, storage atmosphere (air, N2, CO2-N2, and vacuum), storage temperature (4 and 20 degrees C), and recovery media [tryptose phosphate agar (TPA) and modified Oxford agar (MOX)] (P <0.05). Overall, storage at 4 degrees C supported greater survival than storage at 20 degrees C (P< 0.05). Uninjured L. monocytogenes stored at 4 degrees C was recovered on TPA better than sublethally heat-injured L. monocytogenes stored at 40 degrees C (P < 0.05). Recovery of sublethally heat-injured L. monocytogenes stored at 4 degrees C followed the order N2 > CO2-N2 > air > vacuum (P < 0.05), whereas recovery of uninjured L. monocyrogenes stored at 4 degrees C followed the order N2 > CO2-N2 > vacuum > air (P < 0.05). Air and vacuum atmospheres supported greater survival of uninjured and heat-injured L. monocytogenes than N2 and CO2-N2 atmospheres at 20 degrees C (P < 0.05). Recovery of sublethally heat-injured L. monocytogenes stored at 20 degrees C followed the order vacuum > air> CO2-N2 = N2 (P <0.05), whereas recovery of uninjured L. monocytogenes stored at 20 degrees C followed the order vacuum > air> CO2-N2 > N2 (P<0.05). Uninjured L. monocytogenes stored under N2 at 4 degrees C was recovered best, whereas sublethally heat-injured L. monocytogenes stored under N2 at 20 degrees C was recovered poorest (P < 0.05). Factors such as package atmosphere and storage temperature, involved in the production, storage, and distribution of fermented foods must be thoroughly evaluated when determining strategies for control and detection of L. monocytogenes in such products.     

Reading and arithmetic in adolescents with autism spectrum disorders: Peaks and dips in attainment.

In describing academic attainment in autism spectrum disorders (ASD), results are typically reported at the group mean level. This may mask subgroups of individuals for whom academic achievement is incommensurate with intellectual ability. The authors tested the IQ, literacy, and mathematical abilities of a large group (N = 100) of adolescents (14–16 years old) with ASD. Seventy-three percent of the sample had at least one area of literacy or mathematical achievement that was highly discrepant (approximately 14 standard score points) from full-scale IQ (FSIQ). The authors focused on four subgroups with either word reading (“Reading Peak” and “Reading Dip”) or arithmetic (“Arithmetic Peak” and “Arithmetic Dip”) higher or lower than FSIQ. These subgroups were largely mutually exclusive and were characterized by distinct intellectual profiles. The largest was the “Arithmetic Peak” subgroup of participants, who presented with average intellectual ability alongside superior arithmetic skills and who were predominantly in a mainstream educational setting. Overall, the most pervasive profile was discrepantly poor reading comprehension, which associated with severity of social and communication difficulties. The high rate of uneven academic attainment in ASD has implications for educational practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development or a Korotkov Sound Processor for Automatic Identification of Auscultatory Events?Part II Decision Logic Specifications and Operational Verification

An electronic Korotkov sound processor has been developed for the automatic identification of the systolic and diastolic Korotkov sound transitions. This processor incorporates separate circuitry for systolic and diastolic decisions, each with its own defined preprocessing bandpass filter. The decision logic is designed to provide amplitude normalization both within and between subjects, and physiological testing was performed, to optimize the required critical-decision logic parameters. The accuracy of this processor design was evaluated using 32 normal subjects at rest and under orthostatic and ergometric stress conditions. The processor was shown to be quite accurate in its identification of the auscultatory systolic or diastolic event for passive subject conditions; processor accuracy was reduced for subjects participating in ergometric stress.