The most attractive material properties and performance among glassy alloys are derived from microstructures based upon a high number density of nanocrystals dispersed within an amorphous matrix. The ...generation mechanism of these nanocrystal dispersions is still not clear; the present analyses point out that a nearly balanced kinetic competition between crystallization and vitrification is essential but indicate also the involvement of further mechanisms.
Sliding wear behavior of a copper-based bulk metallic glass (Cu sub(50)Hf sub(41.5)Al sub(8.5)) was investigated for both as-cast and annealed samples. The wear resistance increased during isothermal ...annealing near the glass transition temperature. Nanocrystals developed during the annealing for annealing times up to 300 min. A linear relation between hardness and wear resistance was observed during the early stages of devitrification, but at longer annealing times the wear resistance increased less than the hardness. For the as-cast sample and a sample that was structurally relaxed, nanocrystallites developed during sliding and the wear resistance improved for longer sliding distances when the nanocrystals developed. The transmission electron microscopy analysis of the annealed samples suggests that the deviation from the linear hardness vs. wear resistance relation occurs at a critical volume fraction of the nanocrystals. The improvement in wear resistance with sliding appears to result from an increased surface temperature rather than directly from the sliding-induced nanocrystal formation.
Sliding wear behavior of a copper-based bulk metallic glass (Cu
50Hf
41.5Al
8.5) was investigated for both as-cast and annealed samples. The wear resistance increased during isothermal annealing near ...the glass transition temperature. Nanocrystals developed during the annealing for annealing times up to 300
min. A linear relation between hardness and wear resistance was observed during the early stages of devitrification, but at longer annealing times the wear resistance increased less than the hardness. For the as-cast sample and a sample that was structurally relaxed, nanocrystallites developed during sliding and the wear resistance improved for longer sliding distances when the nanocrystals developed. The transmission electron microscopy analysis of the annealed samples suggests that the deviation from the linear hardness vs. wear resistance relation occurs at a critical volume fraction of the nanocrystals. The improvement in wear resistance with sliding appears to result from an increased surface temperature rather than directly from the sliding-induced nanocrystal formation.
Thesis (Ph. D.)--University of Wisconsin--Madison, 2003.
eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (p. 436-482).
The calcium-sensing receptor (CaSR) provides a fundamental mechanism for diverse cells to detect and respond to modulations in the ionic and nutrient compositions of their extracellular milieu. The ...roles for this receptor are largely unknown in the intestinal tract, where epithelial cells are normally exposed to large variations in extracellular solutes. Here, we show that colonic CaSR signaling stimulates the degradation of cyclic nucleotides by phosphodiesterases and describe the ability of receptor activation to reverse the fluid and electrolyte secretory actions of cAMP- and cGMP-generating secretagogues, including cholera toxin and heat stable Escherichia coli enterotoxin STa. Our results suggest a paradigm for regulation of intestinal fluid transport where fine tuning is accomplished by the counterbalancing effects of solute activation of the CaSR on neuronal and hormonal secretagogue actions. The reversal of cholera toxin- and STa endotoxin-induced fluid secretion by a small-molecule CaSR agonist suggests that these compounds may provide a unique therapy for secretory diarrheas.
Patients with ongoing seizures are usually not allowed to drive. The prognosis for seizure freedom is favorable in patients with autoimmune encephalitis (AIE) with antibodies against NMDA receptor ...(NMDAR), leucine-rich glioma-inactivated 1 (LGI1), contactin-associated protein-like 2 (CASPR2), and the gamma-aminobutyric-acid B receptor (GABABR). We hypothesized that after a seizure-free period of 3 months, patients with AIE have a seizure recurrence risk of <20% during the subsequent 12 months. This would render them eligible for noncommercial driving according to driving regulations in several countries.BACKGROUND AND OBJECTIVESPatients with ongoing seizures are usually not allowed to drive. The prognosis for seizure freedom is favorable in patients with autoimmune encephalitis (AIE) with antibodies against NMDA receptor (NMDAR), leucine-rich glioma-inactivated 1 (LGI1), contactin-associated protein-like 2 (CASPR2), and the gamma-aminobutyric-acid B receptor (GABABR). We hypothesized that after a seizure-free period of 3 months, patients with AIE have a seizure recurrence risk of <20% during the subsequent 12 months. This would render them eligible for noncommercial driving according to driving regulations in several countries.This retrospective multicenter cohort study analyzed follow-up data from patients aged 15 years or older with seizures resulting from NMDAR-, LGI1-, CASPR2-, or GABABR-AIE, who had been seizure-free for ≥3 months. We used Kaplan-Meier (KM) estimates for the seizure recurrence risk at 12 months for each antibody group and tested for the effects of potential covariates with regression models.METHODSThis retrospective multicenter cohort study analyzed follow-up data from patients aged 15 years or older with seizures resulting from NMDAR-, LGI1-, CASPR2-, or GABABR-AIE, who had been seizure-free for ≥3 months. We used Kaplan-Meier (KM) estimates for the seizure recurrence risk at 12 months for each antibody group and tested for the effects of potential covariates with regression models.We included 383 patients with NMDAR-, 440 with LGI1-, 114 with CASPR2-, and 44 with GABABR-AIE from 14 international centers. After being seizure-free for 3 months after an initial seizure period, we calculated the probability of remaining seizure-free for another 12 months (KM estimate) as 0.89 (95% confidence interval CI 0.85-0.92) for NMDAR, 0.84 (CI 0.80-0.88) for LGI1, 0.82 (CI 0.75-0.90) for CASPR2, and 0.76 (CI 0.62-0.93) for GABABR.RESULTSWe included 383 patients with NMDAR-, 440 with LGI1-, 114 with CASPR2-, and 44 with GABABR-AIE from 14 international centers. After being seizure-free for 3 months after an initial seizure period, we calculated the probability of remaining seizure-free for another 12 months (KM estimate) as 0.89 (95% confidence interval CI 0.85-0.92) for NMDAR, 0.84 (CI 0.80-0.88) for LGI1, 0.82 (CI 0.75-0.90) for CASPR2, and 0.76 (CI 0.62-0.93) for GABABR.Taking a <20% recurrence risk within 12 months as sufficient, patients with NMDAR-AIE and LGI1-AIE could be considered eligible for noncommercial driving after having been seizure-free for 3 months.DISCUSSIONTaking a <20% recurrence risk within 12 months as sufficient, patients with NMDAR-AIE and LGI1-AIE could be considered eligible for noncommercial driving after having been seizure-free for 3 months.
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