Time-resolved in-situ analysis of phase evolution for the directional solidification of carbon steel weld metal

Kinetic information about the phase transformation, during solidification process and solid-state transformation is essential to the material processing, such as welding. In our research group, in-situ phase identification system consisting of undulator beam and imaging plate have recently been used. The welding torch is driven by stepping-motor in the system. Those make possible that phase transformation can be identified in real-time under the condition of directional solidification and the spatial resolution of 100 × 500 μm. The time-resolution is 0.3125 seconds. In the present work, combination of analyzing method: the in-situ phase identification system, morphological observation by high-temperature laser scanning confocal microscopy and observation of microstructure at room temperature by OM, SEM and micro diffraction-system, is suggested to analyze the phase transformation during welding process. Phase transformation process of hypereutectoid carbon steel, during welding was analyzed as an example of combination observation.     

Magnetic field stability of PrFeB magnets developed by GBD for cryogenic permanent magnet undulators

The magnetic field stability of the PrFeB magnets is one of the key points which affect its application in such devices as cryogenic permanent magnet undulators. In this study, the magnetic properties and microstructure of PrFeB magnets, which were developed by the grain boundary diffusion, were examined. The demagnetizing field distribution of the cryogenic permanent magnet undulator made using the PrFeB magnets was simulated by Radia, and the change mechanism of the irreversible demagnetization following treatments at high temperatures was experimentally studied. The results show that the intrinsic coercivity of the PrFeB magnets can be increased by diffusion of Tb. Meanwhile, the remanence of the magnets displays almost no loss, and the increasing range is closely related to the orientation thickness of the PrFeB magnet. Therefore, the PrFeB magnets developed using grain boundary diffusion are found to have extremely high comprehensive magnetic properties. The irreversible demagnetization of the PrFeB magnets developed by grain boundary diffusion for the CPMU is determined to be significantly improved following high-temperature treatments.     

MAD analysis of FHIT, a putative human tumor suppressor from the HIT protein family

BACKGROUND: The fragile histidine triad (FHIT) protein is a member of the large and ubiquitous histidine triad (HIT) family of proteins. It is expressed from a gene located at a fragile site on human chromosome 3, which is commonly disrupted in association with certain cancers. On the basis of the genetic evidence, it has been postulated that the FHIT protein may function as a tumor suppressor, implying a role for the FHIT protein in carcinogenesis. The FHIT protein has dinucleoside polyphosphate hydrolase activity in vitro, thus suggesting that its role in vivo may involve the hydrolysis of a phosphoanhydride bond. The structural analysis of FHIT will identify critical residues involved in substrate binding and catalysis, and will provide insights into the in vivo function of HIT proteins. RESULTS: The three-dimensional crystal structures of free and nucleoside complexed FHIT have been determined from multiwavelength anomalous diffraction (MAD) data, and they represent some of the first successful structures to be measured with undulator radiation at the Advanced Photon Source. The structures of FHIT reveal that this protein exists as an intimate homodimer, which is based on a core structure observed previously in another human HIT homolog, protein kinase C interacting protein (PKCI), but has distinctive elaborations at both the N and C termini. Conserved residues within the HIT family, which are involved in the interactions of the proteins with nucleoside and phosphate groups, appear to be relevant for the catalytic activity of this protein. CONCLUSIONS: The structure of FHIT, a divergent HIT protein family member, in complex with a nucleotide analog suggests a metal-independent catalytic mechanism for the HIT family of proteins. A structural comparison of FHIT with PKCI and galactose-1-phosphate uridylyltransferase (GaIT) reveals additional implications for the structural and functional evolution of the ubiquitous HIT family of proteins.     

Virus-specific interaction between the human cytomegalovirus major capsid protein and the C terminus of the assembly protein precursor

We previously identified a minimal 12-amino-acid domain in the C terminus of the herpes simplex virus type 1 (HSV-1) scaffolding protein which is required for interaction with the HSV-1 major capsid protein. An alpha-helical structure which maximizes the hydropathicity of the minimal domain is required for the interaction. To address whether cytomegalovirus (CMV) utilizes the same strategy for capsid assembly, several glutathione S-transferase fusion proteins to the C terminus of the CMV assembly protein precursor were produced and purified from bacterial cells. The study showed that the glutathione S-transferase fusion containing 16 amino acids near the C-terminal end was sufficient to interact with the major capsid protein. Interestingly, no cross-interaction between HSV-1 and CMV could be detected. Mutation analysis revealed that a three-amino-acid region at the N-terminal side of the central Phe residue of the CMV interaction domain played a role in determining the viral specificity of the interaction. When this region was converted so as to correspond to that of HSV-1, the CMV assembly protein domain lost its ability to interact with the CMV major capsid protein but gained full interaction with the HSV-1 major capsid protein. To address whether the minimal interaction domain of the CMV assembly protein forms an alpha-helical structure similar to that in HSV-1, peptide competition experiments were carried out. The results showed that a cyclic peptide derived from the interaction domain with a constrained (alpha-helical structure competed for interaction with the major capsid protein much more efficiently than the unconstrained linear peptide. In contrast, a cyclic peptide containing an Ala substitution for the critical Phe residue did not compete for the interaction at all. The results of this study suggest that (i) CMV may have developed a strategy similar to that of HSV-1 for capsid assembly; (ii) the minimal interaction motif in the CMV assembly protein requires an alpha-helix for efficient interaction with the major capsid protein; and (iii) the Phe residue in the CMV minimal interaction domain is critical for interaction with the major capsid protein.     

On the conformation of tiazofurin analogues

Tiazofurin, an important inhibitor of inosine 5'-monophosphate dehydrogenase, has been argued to possess a restricted glycosylic bond due to an energetically favorable intramolecular (1-4) electrostatic interaction between the partial positive sulfur and the negative oxygen of the ribose. This rigidity has been appointed as a plausible cause that leads to activity in the sulfur containing compounds as opposed to the inactive oxazofurin-like analogues (i.e. S is replaced by an oxygen) that lack this favorable interaction. We reinvestigated this notion by using computational methods to report that although the above interaction (or its lack) is likely to contribute to the low-energy conformation of these classes of molecules, the flexibility of the glycosylic bond is ultimately determined by steric interaction of the heteroatoms with the C2'-H and O4' of the ribose. Application of this theory in the design of new analogues is presented as well.     

The effect of ignoring item interactions on the estimated discrimination parameters in item response theory.

Most item response theory models assume conditional independence, and it is known that interactions between items affect the estimated item discrimination. In this article, this effect is further investigated from a theoretical perspective and by means of simulation studies. To this end, a parametric model for item interactions is introduced. Next, it is shown that ignoring a positive interaction results in an overestimation of the discrimination parameter in the two-parameter logistic model (2PLM), whereas ignoring a negative interaction leads to an underestimation of the parameter. Furthermore, it is demonstrated that in some cases the item characteristic curves of the 2PLM and of an item involved in an interaction are quite similar, indicating that the 2PLM can provide a good fit to data with interactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lateral Walking-Induced Forces on Footbridges

In the last several years many cases of large amplitude horizontal vibrations of footbridges have been observed, due to dynamic interaction between the walkers and the footbridge, which may occur when some conditions on the bridge mass, frequency and damping, as well as on the crowd density are met. Such interaction is an intriguing phenomenon, as it is associated with the dynamics of a complex system made of a structure and a number of walkers, the dynamics of the latter being governed by physiology and psychology. Provided this complexity, in this paper a preliminary step is made toward the modeling of the interaction forces exerted by a crowd to a footbridge. The results of an experimental investigation of the lateral forces exerted by one walker to a fixed floor are presented, and used to calibrate a deterministic and stochastic lateral loading models of footbridges, to be used in the case in which no interaction takes place. The results presented are also the background data for more sophisticated dynamic models allowing for bridge-crowd interaction.     

Type IV errors and interactions.

Extends L. A. Marascuilo and J. R. Levin's notion of Type IV errors, emphasizing the interpretation of interactions in factorial analysis of variance (ANOVA) designs. To help clarify what an interaction is and what it is not in terms of the ANOVA model, it is emphasized that (a) comparisons designed to explain an interaction are acceptable only if they reduce to comparisons involving interaction parameters exclusively; and (b) such comparisons may be both specified and directional, i.e., they may be defined to test an E's a priori hypotheses. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of Soil–Multiple Contaminant Retention Parameters on Contaminant Fate Prediction

Determination of contaminant interaction with soil is essential for predicting its fate in geoenvironments. Several studies have appraised contaminant fate prediction based on the results of single contaminant-soil interaction. Although a few studies deal with multiple contaminant-soil interaction, its influence on contaminant fate prediction is not discussed in detail. Therefore, the present study will investigate the influence of multiple contaminant-soil interaction results about contaminant fate prediction. The influence of different ranges of contaminant concentration on fate prediction has also been studied. Results indicate that contaminant fate prediction based on multiple contaminant-soil interaction is higher than single contaminant interaction. Contaminant fate prediction based on linear isotherms is influenced by the range of concentration for single and multiple contaminants. For a lower range of concentration, contaminant fate prediction based on the Freundlich isotherm is greater than that of Langmuir, and vice versa for higher concentration ranges. Furthermore, the difference in contaminant fate prediction based on Freundlich and Langmuir nonlinear isotherms decreases with an increase in concentration.     

Semantic effects in naming perceptual identification but not in delayed naming: Implications for models and tasks.

Previous research has demonstrated that the subjective danger and usefulness of words affect lexical decision times. Usually, an interaction is found: Increasing danger predicts faster reaction times (RTs) for words low on usefulness, but increasing danger predicts slower RTs for words high on usefulness. The authors show the same interaction with immediate auditory naming. The interaction disappeared with a delayed auditory naming control experiment, suggesting that it has a perceptual basis. In an attempt to separate input (signal to ear) from output (brain to muscle) processes in word recognition, the authors ran 2 auditory perceptual identification experiments. The interaction was again significant, but performance was best for words high on both danger and usefulness. This suggests that initial demonstrations of the interaction were reflecting an output approach/withdraw response conflict induced by stimuli that are both dangerous and useful. The interaction cannot be characterized as a tradeoff of speed versus accuracy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social transmission of food preference in mice: Methodology and application to galanin-overexpressing transgenic mice.

Social transmission of food preference (STFP) is a test of olfactory memory that can be used in mice. Confounds in STFP that can lead to misinterpretation of an STFP deficit as a memory impairment include changes in social interaction and olfaction. The issue of changes in social interaction was addressed by evaluating an observer-centric and a demonstrator-centric method for scoring the interaction phase of STFP in mice. The demonstrator-centric method was applied to a line of STFP-impaired, galanin-overexpressing transgenic (GAL-tg). GAL-tg mice were impaired in STFP without deficits in social interaction. In tests of olfactory ability, GAL-tg mice were unimpaired on buried-food and habituation-dishabituation tasks. The current studies describe an expanded method for using STFP in mice and confirm a deficit in olfactory memory in GAL-tg mice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiple spatial correspondence effects on dual-task performance.

Three dual-task experiments were conducted to examine whether the underadditive interaction of the Simon effect and stimulus onset asynchrony (SOA) on Task 2 performance is due to decay. The experiments tested whether the reverse Simon effect obtained with an incompatible stimulus–response (S-R) mapping would show an overadditive interaction with SOA, as predicted by R. De Jong, C.-C. Liang, and E. Lauber's (1994) dual-process model. Tone or letter identification tasks with vocal or keypress responses were used as Task 1. Task 2 was keypresses to arrow direction (or letter identity in Experiment 1). For all experiments, the normal Simon effect showed an underadditive interaction with SOA, but the reverse Simon effect did not show an overadditive interaction. The results imply that the dual-process model is not applicable to the dual-task context. Multiple correspondence effects across tasks implicate an explanation in terms of automatic S-R translation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Elastic interaction energy of two spherical precipitates in an anisotropic matrix

Following the difference method of Eshelby, the elastic interaction energy between two spherical precipitates embedded in an infinite matrix of cubic anisotropy is studied as a function of their distance of separation and alignment direction. When the precipitates are positioned along the [100] direction of the matrix phase, the elastic interaction is found to be attractive and often to exhibit a maximum value at an intercenter distance of two to three radii. For the [110] and [111] alignments, the results depend on the sign of the anisotropic factor,H=2C₄₄+C₁₂−C₁₁, of the matrix phase. When it is positive as in Cu and Ni, the interaction is found to be repulsive. In the reverse case, the situation is substantially different; for the [111] alignment with a Mo matrix, the interaction is found to be of an attractive nature.     

高炉内天然块矿与烧结矿高温交互反应研究

单一块矿的冶金性能是高炉选择使用块矿的重要技术指标.在实验室分别研究块矿、烧结矿及其混合炉料软化特征的基础上,研究了块矿在高炉高温区与烧结矿之间的交互作用情况,提出了高炉高温区内天然块矿与烧结矿交互反应性的新概念,同时给出了它的测定及评价方法,并结合综合炉料的熔滴性能考察了天然块矿高温反应的影响.     

Mechanisms of inhibition of amido phosphoribosyltransferase from mouse L1210 leukemia cells

Amido phosphoribosyltransferase (amido PRTase) catalyses the first step of the pathway for de novo biosynthesis of purine nucleotides. The enzyme is subject to inhibition by purine nucleoside 5'-monophosphates (AMP, IMP, and GMP), by dihydrofolate polyglutamates, and by the antifolate piritrexim [Sant, M. E., Lyons, S. D., Phillips, L., & Christopherson, R. I. (1992) J. Biol. Chem. 267, 11038-11045). Using a coupled radioassay, we have determined the substrate dissociation constants as 80.4 +/- 13.2 microM for 5-phosphoribosyl 1-pyrophosphate (P-Rib-PP) and 421 +/- 193 microM for L-glutamine with P-Rib-PP bound first with positive cooperativity for interaction with a second site on the catalytically active dimer (interaction factor of 0.247 +/- 0.042). Analysis of inhibition patterns for amido PRTase shows that the antifolate piritrexim is a noncompetitive inhibitor bound with positive cooperativity at two allosteric sites of an inactive dimer with a dissociation constant of 66.0 +/- 17.8 microM for interaction with the free enzyme and an interaction factor of 0.187 +/- 0.113 with P-Rib-PP as the varied substrate. With L-glutamine as the varied substrate, a dissociation constant of 62.3 +/- 15.6 microM for interaction with the enzyme-P-Rib-PP complex and an interaction factor of 0.0958 +/- 0.0585 microM were obtained. AMP binds as a competitive inhibitor with respect to P-Rib-PP with a dissociation constant of 40.0 +/- 8.1 microM for interaction with the free enzyme and as a noncompetitive inhibitor with respect to L-glutamine with a dissociation constant of 16.4 +/- 5.2 mM for interaction with the enzyme-P-Rib-PP complex. Sucrose density gradient centrifugation of partially purified amido PRTase showed three molecular forms of the enzyme: an inactive tetramer (10.2 S) formed in the presence of AMP, an active dimer (6.7 S) formed with P-Rib-PP, and an inactive dimer (7.2 S) with piritrexim. The latter species may predominate in cells containing high levels of dihydrofolate polyglutamates.     

Domains mediating intramolecular folding and oligomerization of MxA GTPase

MxA is an interferon-induced GTPase of human cells that inhibits the multiplication of several RNA viruses by a still poorly understood mechanism. Previous biochemical studies indicated that the C terminus of MxA folds back to form a functional GTP-binding pocket, and that an internal fragment contains a domain required for oligomerization. Using the yeast two-hybrid system, we have now mapped these domains. MxA sequences located downstream of amino acid 564 were found to strongly interact with an internal domain that includes amino acids 372 to 540. This interaction was abolished by mutating phenylalanine 382 or leucine 612, which is part of a leucine zipper motif. Neither the C-terminal nor the internal MxA fragments formed homo-oligomers. Using a mammalian nuclear transport assay that can detect protein-protein interactions, we further found that full-length MxA forms complexes with MxA fragments that include amino acids 372 to 540. This interaction was not observed when phenylalanine 382 was exchanged for alanine or arginine. Furthermore, interaction of two full-length MxA molecules occurred only if at least one of them carried a functional C-terminal leucine zipper motif. These results suggest that C-terminal back-folding and oligomerization are two alternative outcomes of the same type of interaction between the C-terminal and the internal domains of MxA. Intramolecular interaction is believed to result in the formation of MxA monomers, whereas intermolecular interaction may induce the formation of large MxA oligomers.     

Angular dependences of the hysteretic characteristics and the magnetization reversal of high-coercivity co-based alloy films

The relation is studied between the structural characteristics and the magnetic intercrystallite interaction and the magnetization reversal processes in films of Co-W alloys and Co-containing nanostructures on the anodic aluminum oxide surface. It is shown that the magnetostatic interaction of crystallites in the Co-W films provides a deviation of experimental H _c (φ) curves from the model of noninteracting crystallites; in this case, an increase in the magnetostatic interaction leads to an increase in the fraction of rotational processes during magnetization reversal.     

Grain boundary segregation in a low alloy steel under tensile loading conditions

The influence of tensile stress on the grain boundary segregation behaviour in a NiCrMoV steel is elucidated through the measurement of grain boundary segregation isotherms and the determination of interaction processes amongst trace and alloying elements. The application of tensile stress accelerates and enhances the grain boundary coverage of elements P, N and S presumably through a stress-induced-diffusion process. The qualitative nature of the interaction processes which are operative in the absence of any applied stress remain unaltered on the application of the tensile stress. However, there is an enhancement of the interaction processes, in the presence of the applied stress; site-competitive, P + S, interaction process is particularly activated in the presence of a tensile stress.     

Potential interaction between warfarin and fluvastatin

OBJECTIVE: To report three cases of a suspected interaction between warfarin and fluvastatin. CASE SUMMARIES: Three patients receiving stable warfarin dosages with therapeutic international normalized ratios (INRs) exhibited increased INRs when fluvastatin was added to their maintenance regimens. While none of the patients experienced a bleeding episode, they did require a reduction in their weekly warfarin dosage to achieve an appropriate level of anticoagulation. DISCUSSION: Reports of an interaction between warfarin and lovastatin have been described previously; however, to our knowledge, this is the first published report of a possible interaction between warfarin and fluvastatin. These cases were chosen because other factors that could potentially increase the INR were ruled out as significant contributors. CONCLUSIONS: The exact mechanism for the potential interaction between warfarin and fluvastatin is unknown. Until more is known, it is advisable to monitor patients more frequently when fluvastatin is initiated, discontinued, or adjusted in patients taking warfarin.