Standard heat treatment (HT1) for Inconel 718 superalloy is solutionizing at 1095
°C, 1
h/AC, then aging at 955
°C, 1
h/AC
+
720
°C, 8
h/FC 57
K/h to 620
°C, 8
h/AC. In order to study the aging ...effects of the δ phase, two more conditions HT2 (no aging condition 955
°C) and HT3 (955
°C, 3.5
h/AC) were studied in this research. Lever arm creep tests were performed at 650
°C under constant stress 625
MPa. Since HT2 produces no δ phase, the stress rupture life, creep elongation to failure and steady state creep rate of HT2 are largest among these three aging conditions. However, increasing the 955
°C aging time, the stress rupture life, creep elongation and steady state creep rate raise slightly as compared to HT1, because platelet δ phase is more uniformly nucleated and more direction oriented at grain boundaries. Fractographs show ductile fracture patterns mostly and, small portion of inter-granular fracture in the HT2 specimens. Generally only inter-granular fracture is observed in the other two cases of HT1 and HT3. Besides twinning and dislocation mechanisms, grain boundary sliding is also activated, so that creep elongation to failure of HT2 specimens could reach 5.6%, whereas 1% for the other two schemes.
The antiferroelectricity in HfZrO 2 (HZO) annealed at 600 °C with an abrupt turn ON of FET characteristics with SSmin = 23 mV/dec and SSavg = 50 mV/dec over 4 decades of IDS is demonstrated. The near ...non-hysteresis is achieved with an antiferroelectric-like HZO due to a small remanent polarization and a coercive field. A feasible concept of coupling the antiferroelectric and ferroelectric type HZO are used for low-power electronics and the memory applications, respectively.
Somatic mutations in mitochondrial DNA (mtDNA) have been detected in hepatocellular carcinoma (HCC). However, it remains unclear whether mtDNA copy number and mitochondrial biogenesis are altered in ...HCC. In this study, we found that mtDNA copy number and the content of mitochondrial respiratory proteins were reduced in HCCs as compared with the corresponding non-tumorous livers. MtDNA copy number was significantly reduced in female HCC but not in male HCC. Expression of the peroxisome proliferator-activated receptor gamma coactivator-1 was significantly repressed in HCCs (P<0.005), while the expression of the mitochondrial single-strand DNA-binding protein was upregulated, indicating that the regulation of mitochondria biogenesis is disturbed in HCC. Moreover, 22% of HCCs carried a somatic mutation in the mtDNA D-loop region. The non-tumorous liver of the HCC patients with a long-term alcohol-drinking history contained reduced mtDNA copy number (P<0.05) and higher level of the 4977 bp-deleted mtDNA (P<0.05) as compared with non-alcohol patients. Our results suggest that reduced mtDNA copy number, impaired mitochondrial biogenesis and somatic mutations in mtDNA are important events during carcinogenesis of HCC, and the differential alterations in mtDNA of male and female HCC may contribute to the differences in the clinical manifestation between female and male HCC patients.
Low strain hardening has hitherto been considered an intrinsic behavior for most nanocrystalline (NC) metals, due to their perceived inability to accumulate dislocations. In this Letter, we show ...strong strain hardening in NC nickel with a grain size of approximately 20 nm under large plastic strains. Contrary to common belief, we have observed significant dislocation accumulation in the grain interior. This is enabled primarily by Lomer-Cottrell locks, which pin the lock-forming dislocations and obstruct dislocation motion. These observations may help with developing strong and ductile NC metals and alloys.
It is well attested that high socio‐economic status (SES) is associated with larger vocabulary size estimates in young children. This has led to growing interest in identifying associations and ...mechanisms that may contribute to this relationship. In this study, parent‐child reading behaviors were investigated in relation to vocabulary size in a large‐scale study of linguistically and socio‐economically diverse families. This study sampled 902 infants in Singapore, a multilingual society. Both single‐language (dominant and non‐dominant) and dual‐language vocabulary size estimates were obtained and related to family SES, demographic details, and home literacy activities. Results demonstrated that both single‐language (dominant and non‐dominant) and dual‐language infant vocabulary size estimates were predicted by parental education levels. Further analyses revealed that parent‐child book reading activities mediated the relationship between parental education and infant vocabulary size. Findings suggest that shared book reading may narrow effects of socio‐economic disparities on early language development.
Research Highlights
Socio‐economic status (SES) was examined in relation to infant vocabulary size in a linguistically and socio‐economically diverse setting.
Mediating effects of the home literacy environment on infant vocabulary size were measured.
Socio‐economic factors, notably parental education, had both direct and indirect effects on vocabulary size.
The home literacy environment mediated effects of SES on infant vocabulary size.
This study focuses on the relationship between parent‐child bookreading, socio‐economic status, and vocabulary development. Findings suggest that parent‐child bookreading may protect against against socio‐economic vulnerability in language development.
Using a conjunction of Cluster in the mid‐altitude dayside magnetosphere and Swarm in the low‐altitude ionosphere, we show, by employing multi‐spacecraft analysis, that matched, strong magnetic ...perturbations and the corresponding mesoscale field‐aligned current (FAC) structures are measured in the high latitude polar cusp region during the 7 October 2015 storm. Two pairs of opposite (positive/negative) FACs are observed by both Cluster and Swarm, which may relate to pulsed magnetic reconnection at the dayside magnetopause. Furthermore, the current intensity of these matched FACs decreases from high to low latitude, consistent with the time elapsed since reconnection. Corresponding geomagnetic disturbances are also observed by ground stations. Our observations provide direct evidence for the coupling of mesoscale FACs between the magnetosphere, ionosphere and ground in the polar cusp region, where the signatures are driven in this case by conditions suitable for inducing reconnection.
Plain Language Summary
Field‐aligned currents (FACs) are the key medium for the interaction between the distant space magnetosphere (a region filled with Earth's magnetic field) and the near‐Earth space ionosphere. Magnetic reconnection is the most important process to transfer solar wind energy from dayside magnetosphere to nightside, which is accompanied by the generation of FACs extending from the high latitude region of the ionosphere to the magnetosphere. For such structures, extending across different space regions, joint observations by multiple spacecraft are necessary. Using simultaneous measurements of Cluster in the magnetosphere, Swarm in the ionosphere and geomagnetic stations on the ground, coordinated mesoscale FAC structures could show matched signatures in the magnetosphere and the ionosphere and the corresponding geomagnetic disturbances on the ground. Our observations provide direct evidence for the magnetosphere‐ionosphere‐ground coupling during the pulsed magnetic reconnection process.
Key Points
Multi‐spacecraft Cluster and Swarm reveal matched magnetic perturbation and corresponding mesoscale field‐aligned currents (FACs) at different altitudes in the cusp region
Multiple pairs of opposite FACs associated with pulsed magnetic reconnection are dominant currents system at the dayside during storm time
Direct evidence for detailed dayside mesoscale FACs coupling between magnetosphere, ionosphere and ground is provided
Although near-field microscopy has allowed optical imaging with sub-20 nm resolution, the optical throughput of this technique is notoriously small. As a result, applications such as optical data ...storage have been impractical. However, with an optimized near-field transducer design, we show that optical energy can be transferred efficiently to a lossy metallic medium and yet remain confined in a spot that is much smaller than the diffraction limit. Such a transducer was integrated into a recording head and flown over a magnetic recording medium on a rotating disk. Optical power from a semiconductor laser at a wavelength of 830 nm was efficiently coupled by the transducer into the medium to heat a 70-nm track above the Curie point in nanoseconds and record data at an areal density of ∼375 Tb m-2 . This transducer design should scale to even smaller optical spots.
Abstract
In addition to serving as the power house of mammalian cells, mitochondria are crucial for the maintenance of cellular homeostasis in response to physiological or environmental changes. ...Several lines of evidence suggest that posttranslational modification (PTM) of proteins plays a pivotal role in the regulation of the bioenergetic function of mitochondria. Among them, reversible lysine acetylation of mitochondrial proteins has been established as one of the key mechanisms in cellular response to energy demand by modulating the flux of a number of key metabolic pathways. In this article, we focus on the role of Sirt3-mediated deacetylation in: (1) flexibility of energy metabolism, (2) activation of antioxidant defense, and (3) maintenance of cellular redox status in response to dietary challenge and oxidative stress. We suggest that oxidative stress-elicited down-regulation of Sirt3 plays a role in the pathophysiology of diabetes, cardiac hypotrophy, mitochondrial diseases, and age-related diseases. Besides, the physiological role of newly identified lysine acylation mediated by Sirt5 and its biochemical effects on oxidative metabolism are also discussed. Moreover, we have integrated the regulatory function of several protein kinases that are involved in the phosphorylation of mitochondrial enzymes during oxidative stress. Finally, the functional consequence of the synergistic regulation through diverse protein modifications is emphasized on the maintenance of the bioenergetic homeostasis and metabolic adaptation of the animal and human cells. Together, we have provided an updated review of PTM in mitochondrial biology and their implications in aging and human diseases through an intricate regulation of energy metabolism under oxidative stress.
PDF
