1,755 research outputs found
Work hardening behavior in a steel with multiple TRIP mechanisms
Transformation induced plasticity (TRIP) behavior was studied in steel with
composition Fe-0.07C-2.85Si-15.3Mn-2.4Al-0.017N that exhibited two TRIP
mechanisms. The initial microstructure consisted of both {\epsilon}- and
{\alpha}-martensites with 27% retained austenite. TRIP behavior in the first 5%
strain was predominately austenite transforming to {\epsilon}-martensite (Stage
I), but upon saturation of Stage I, the {\epsilon}-martensite transformed to
{\alpha}-martensite (Stage II). Alloy segregation also affected the TRIP
behavior with alloy rich regions producing TRIP just prior to necking. This
behavior was explained by first principle calculations that revealed aluminum
significantly affected the stacking fault energy in Fe-Mn-Al-C steels by
decreasing the unstable stacking fault energy and promoting easy nucleation of
{\epsilon}-martensite. The addition of aluminum also raised the intrinsic
stacking fault energy and caused the {\epsilon}-martensite to be unstable and
transform to {\alpha}-martensite under further deformation. The two stage TRIP
behavior produced a high strain hardening exponent of 1.4 and led to ultimate
tensile strength of 1165 MPa and elongation to failure of 35%.Comment: submitted to Met. Mater. Trans. A manuscript E-TP-12-953-
Predicting young children's externalizing problems:Interactions among effortful control, parenting, and child sex
This study investigated interactions between observed temperamental effortful control and observed parenting in the prediction of externalizing problems. Child gender effects on these relations were examined. The relations were examined concurrently when the child was 3 years old and longitudinally at 4.5 years. The sample included 89 two-parent families and their firstborn children. Children with a low level of effortful control were most at risk of displaying externalizing problems. However, more parental positive control seemed to buffer this risk. Boys were at risk of displaying externalizing problems, but again this was buffered by parental positive control. Effortful control was more strongly related to concurrent externalizing problems in boys than in girls, but girls’ effortful control had a greater long-term effect on externalizing problems
Transthyretin levels in the vitreous correlate with change in visual acuity after vitrectomy
Background/aim: Little is known about biochemical markers related to change in visual acuity after vitrectomy. The potential use of transthyretin (TTR), a carrier of the retinol/retinol-binding protein, as a biochemical marker protein, was investigated.
Methods: TTR was measured using immunonephelometry in a group of patients (n = 77) in longstanding (> 1 week) retinal detachment (n = 29), fresh (< 1 week) retinal detachment (n = 17), macular holes (n = 20) or diabetic retinopathy (n = 11). Vitreous samples were taken at the start of every vitrectomy procedure. For reference values, cadaver specimens (n = 73) were used.
Results: Reference values for vitreous TTR (median 18 mg/l; IQR 4 to 24 mg/l) comprised 2.2% of reference values for vitreous protein levels (median 538 mg/l; IQR 269 to 987 mg/l). Vitreous TTR values of patients were comparable in all disorders. Vitreous TTR values were higher in phakic (median 22.5 mg/l; IQR 10 to 27 mg/l) than in pseudophakic patients (median 12 mg/l; IQR 8 to 19 mg/l; p = 0.06). Postoperative change in visual acuity correlated well with vitreous TTR values found peroperatively (r(s) = 0.408; p = 0.012). Both change in visual acuity and lens status were the only variables which proved to explain the variance of TTR (multiple correlation coefficient: 0.494; phakic status: t = 2.767; p = 0.0084; and change in visual acuity t = 2.924: p = 0.0056).
Conclusion: Vitreous fluid concentrations of TTR can be regarded as a biochemical marker for retinal function
Decadal and multi-decadal variability of Labrador Sea Water in the north-western North Atlantic Ocean derived from tracer distributions: Heat budget, ventilation, and advection
Time series of profiles of potential temperature, salinity, dissolved oxygen, and planetary potential vorticity at intermediate depths in the Labrador Sea, the Irminger Sea, and the Iceland Basin have been constructed by combining the hydrographic sections crossing the sub-arctic gyre of the North Atlantic Ocean from the coast of Labrador to Europe, occupied nearly annually since 1990, and historic hydrographic data from the preceding years since 1950. The temperature data of the last 60 years mainly reflect a multi-decadal variability, with a characteristic time scale of about 50 years. With the use of a highly simplified heat budget model it was shown that this long-term temperature variability in the Labrador Sea mainly reflects the long-term variation of the net heat flux to the atmosphere. However, the analysis of the data on dissolved oxygen and planetary potential vorticity show that convective ventilation events, during which successive classes of Labrador Sea Water (LSW) are formed, occurring on decadal or shorter time scales. These convective ventilation events have performed the role of vertical mixing in the heat budget model, homogenising the properties of the intermediate layers (e.g. temperature) for significant periods of time. Both the long-term and the near-decadal temperature signals at a pressure of 1500 dbar are connected with successive deep LSW classes, emphasising the leading role of Labrador Sea convection in running the variability of the intermediate depth layers of the North Atlantic. These signals are advected to the neighbouring Irminger Sea and Iceland Basin. Advection time scales, estimated from the 60 year time series, are slightly shorter or of the same order as most earlier estimates, which were mainly based on the feature tracking of the spreading of the LSW(94) class formed in the period 1989-1994 in the Labrador Sea
Ruddlesden-Popper faults in LaNiO3/LaAlO3 superlattices
Scanning transmission electron microscopy in combination with electron
energy-loss spectroscopy is used to study LaNiO3/LaAlO3 superlattices grown on
(La,Sr)AlO4 with varying single-layer thicknesses which are known to control
their electronic properties. The microstructure of the films is investigated on
the atomic level and the role of observed defects is discussed in the context
of the different properties. Two types of Ruddlesden-Popper faults are found
which are either two or three dimensional. The common planar Ruddlesden-Popper
fault is induced by steps on the substrate surface. In contrast, the
three-dimensionally arranged Ruddlesden-Popper fault, whose size is in the
nanometer range, is caused by the formation of local stacking faults during
film growth. Furthermore, the interfaces of the superlattices are found to show
different sharpness, but the microstructure does not depend substantially on
the single-layer thickness.Comment: 14 pages, 6 figure
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