Mechanism for the Peritectic Reaction and Growth of Aligned Grains in YBa2Cu3O6+x

It is experimentally observed that the peritectic reaction, 211 + liquid → 123, can be driven essentially to completion in 1 h at an undercooling of only ∽30°C. The kinetic data, together with the observed microstructures, are inconsistent with the normal mechanism of the peritectic reaction. It is proposed that the mechanism of the reaction involves dissolution of 211 particles into the liquid and precipitation of solid 123. The aligned grain structure is explained through sympathetic nucleation of new 123 grains on existing grains.     

50-nm Self-Aligned and “Standard” T-gate InP pHEMT Comparison: The Influence of Parasitics on Performance at the 50-nm Node

Continued research into the development of III-V high-electron mobility transistors (HEMTs), specifically the minimization of the device gate length, has yielded the fastest performance reported for any three terminal devices to date. In addition, more recent research has begun to focus on reducing the parasitic device elements such as access resistance and gate fringing capacitance, which become crucial for short gate length device performance maximization. Adopting a self-aligned T-gate architecture is one method used to reduce parasitic device access resistance, but at the cost of increasing parasitic gate fringing capacitances. As the device gate length is then reduced, the benefits of the self-aligned gate process come into question, as at these ultrashort-gate dimensions, the magnitude of the static fringing capacitances will have a greater impact on performance. To better understand the influence of these issues on the dc and RF performance of short gate length InP pHEMTs, the authors present a comparison between In_0.7Ga_0.3As channel 50-nm self-aligned and "standard" T-gate devices. Figures of merit for these devices include transconductance greater than 1.9 S/mm, drive current in the range 1.4 A/mm, and fT up to 490 GHz. Simulation of the parasitic capacitances associated with the self-aligned gate structure then leads a discussion concerning the realistic benefits of incorporating the self-aligned gate process into a sub-50-nm HEMT system     

Laser Induced Liquid Phase Reaction Synthesis Assisted Joining of Metal Matrix Composites

A Laser Induced Liquid Phase Reaction Synthesis Assisted Joining technique is employed for SiC-particulate/Al-alloy composite to produce joints. Joints in SiC/Al-alloy composite are produced by synthesis of suitable material product as a result of interaction between composite and Ti (or Ti-alloy) reactive filler material induced by laser energy in the joint region. Such reaction product minimizes or eliminates the formation of deleterious aluminum carbide phase in the joint region depending upon the type and nature of die interfacial reactive filler material and also the laser processing parameters. A laser beam is utilized to both synthesize the interfacial reactant mixture and to heat the base material adjacent to the joint region to minimize the thermal stresses. The technique along with suitable filler material, further can be extended to a variety of metal matrix composite systems including combinations of Gr/Al, B/Al, B₄C/Mg, Steel/Al, W/Al, Al₂ O₃ and Gr/Cu which are excellent for use in various automotive, aerospace and electronic applications. Preliminary observations describing the proof of concept of laser induced reaction joining of metal matrix composites are reported     

Contextual cues aid recovery from interruption: The role of associative activation.

A series of experiments introduced interruptions to the execution phase of simple Tower of London problems and found that the opportunity for preparation before the break in task reduced the time cost at resumption. Retrieval of the suspended goal was facilitated when participants were given the opportunity to encode retrieval cues during an "interruption lag" (the brief time before engaging in the interrupting task) but was impeded when these visual cues were subsequently altered following interruption. The results provide useful support for the goal-activation model (E. M. Altmann & G. J. Trafton, 2002), which assumes that context--at the points of both goal suspension and goal retrieval--is critical to efficient interruption recovery. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polycyclic Aromatic Hydrocarbons Activate the Aryl Hydrocarbon Receptor and the Constitutive Androstane Receptor to Regulate Xenobiotic Metabolism in Human Liver Cells

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants produced by incomplete combustion of organic matter. They induce their own metabolism by upregulating xenobiotic-metabolizing enzymes such as cytochrome P450 monooxygenase 1A1 (CYP1A1) by activating the aryl hydrocarbon receptor (AHR). However, previous studies showed that individual PAHs may also interact with the constitutive androstane receptor (CAR). Here, we studied ten PAHs, different in carcinogenicity classification, for their potential to activate AHR- and CAR-dependent luciferase reporter genes in human liver cells. The majority of investigated PAHs activated AHR, while non-carcinogenic PAHs tended to activate CAR. We further characterized gene expression, protein abundancies and activities of the AHR targets CYP1A1 and 1A2, and the CAR target CYP2B6 in human HepaRG hepatoma cells. Enzyme induction patterns strongly resembled the profiles obtained at the receptor level, with AHR-activating PAHs inducing CYP1A1/1A2 and CAR-activating PAHs inducing CYP2B6. In summary, this study provides evidence that beside well-known activation of AHR, some PAHs also activate CAR, followed by subsequent expression of respective target genes. Furthermore, we found that an increased PAH ring number is associated with AHR activation as well as the induction of DNA double-strand breaks, whereas smaller PAHs activated CAR but showed no DNA-damaging potential.     

Zeolite‐catalyzed isomerization of oleic acid to branched‐chain isomers

Branched‐chain (bc) saturated fatty acids (SFA) have potential as oleochemical intermediates since they have better oxidative stability than linear unsaturated fatty acids (UFA) and have better low‐temperature properties than linear SFA. Previous studies in converting UFA to bc‐FA using clay catalysts have resulted in only modest yields and conversions. Recent reports, however, have suggested that certain zeolites can be effective catalysts for converting UFA to bc‐FA in higher yields and conversions. In this work, we examined the scope and potential of the zeolite‐catalyzed synthesis of bc‐FA starting from readily available monounsaturated linear FA. Our results show that common UFA such as oleic acid can be converted to bc‐isomers using modified Ferrierite zeolite catalysts with high conversions (98%) and high selectivity (85%) and that the zeolite catalysts are reusable for at least three cycles. The positions of branching (methyl) on the FA chain were determined from the GC‐MS spectra of the picolinyl esters of the bc‐FA.     

Edible oil evaluation by room odor tests: A preliminary report

Room odors developed on heating edible fats in open vessels were evaluated and characterized by a 20 member odor panel. Edible fats tested were: special soybean salad and cooking oils, hydrogenated soybean oil and some commercial salad and cooking oils. Factors were investigated that affect reliability and reproducibility of the test and the acuity of the panel members. The effects of fry temperature and size of sample were investigated. The method has been applied to a study of hydrogenated and unhydrogenated soybean oil samples. Presented at the AOCS Meeting, Chicago, September 1970. No. Market. Nutr. Res. Div., ARS, USDA.     

Long term storage of soybean and cottonseed salad oils

Commercially prepared and packaged soybean and cottonseed salad oils from several different processors were evaluated periodically during storage for 12 months. Partially hydrogenated and winterized soybean oils, as well as unhydrogenated soybean salad oils, were stored in bottles and cans at 78 and 100 F. Control samples of all oils were held at 0 F during the entire test. Some lots in bottles and cans were packaged under nitrogen to improve storage stability. Agreement was good between organoleptic and oxidative evaluation of aged oils. After 26 weeks of storage at 100 F, the flavor of partially hydrogenated-winterized oils packaged under nitrogen showed a minimum loss. These same oils did not exhibit much, if any, reduction in their oxidative stability as indicated by storage peroxide values (active oxygen method). Soybean oil not protected with nitrogen demonstrated progressive flavor deterioration at 100 F. After 10 weeks of storage, the deterioration became marked and the flavor score was below 5. From limited observations, bottled oils appear to have a better stability than oils packaged in screw-cap tin cans. Hydrogenated oils packaged under nitrogen in cans had good oxidative stability, but some lowering of the flavor score was observed. Nonhydrogenated soybean oils packaged in tin cans not under nitrogen exhibited the most rapid flavor deterioration of all lots of oil investigated. Presented in part at the AOCS meeting, New York, October 1968 ARS, USDA     

Dual Verbal Elicitation: The Complementary Use of Concurrent and Retrospective Reporting Within a Usability Test

Verbal protocols are the primary tool for understanding users' task-solving behaviors during usability testing. A qualitative study that examined the utility of combining a concurrent and retrospective think-aloud within the same usability test is described. The results indicate that although there was significant overlap between the types of utterances produced during each think-aloud, the retrospective phase produced more verbalizations that were relevant to usability analysis, for example, helpful self-assessments of performance, yielding insights into the impact of encountered difficulties. However, a small number of less desirable utterance types emerged: hypothesising, rationalizing, and forgetting. When used together, both methods contributed to an understanding of usability issues; the concurrent phase yielded more usability issues overall, and the retrospective data improved the understanding of these by (a) reinforcement: users highlighted the impact of an issue on their experience, (b) elaboration: users would provide causal explanations of encountered difficulties, and (c) context: users provided information about the product's context of use.     

Protein profiling of low-density lipoprotein from obese subjects

Although obesity and high levels of low-density lipoprotein (LDL) are well-known risk factors for cardiovascular disease, the precise role(s) of different LDL constituents in obesity has not been explored. In the present study, we compared the LDL proteome of healthy control adults (body mass index<25) and obese subjects (body mass index>30). LDL was isolated by density-gradient ultracentrifugation and proteins were separated with 2-D PAGE, quantified, and identified by peptide mass fingerprinting using MALDI-TOF MS. A new LDL-associated protein was identified as transthyretin and found to be significantly more abundant in LDL from the obese subjects. In addition, LDL from the obese subjects contained relatively more α(1) -antitrypsin, apo J, apo C-II, than LDL from controls, and also more of an acidic isoform (pI/Mr; 5.2/23 100) of apo A-I. On the other hand, the relative amounts of apo A-IV and the major isoform of apo A-I (pI/Mr; 5.3/23 100) were significantly less in LDL from the obese subjects. Apo E was less and non-sialylated apo C-III more abundant in LDL from obese men than control men, while there were no such differences between LDL from obese and control women. These findings illustrate that obesity is not only associated with increased LDL-cholesterol levels but also with alterations in the LDL protein composition. The presence of transthyretin in LDL from obese subjects may reflect over-nutrition and affect the lipid metabolism in obesity.