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The cycling endurance of phase-change memory is one of the last hurdles to overcome to enable its adoption in the larger market for persistent memory products. Phase-change memory cycling endurance failures, whether they are stuck-SET (caused by elemental segregation) or stuck-RESET (caused by void formation), are caused by atomic migration. Various driving forces responsible for the atomic migration have been identified, such as hole-wind force, electrostatic force, and crystallization-induced segregation. We introduce several strategies to improve cycling endurance based on an understanding of driving forces and interactions among them. Utilizing some of these endurance-improving techniques, record-high phase-change memory cycling endurance at around 1012 cycles has been recently reported using a confined phase-change memory cell with a metallic liner.
The choice of materials that constitute electrodes and the way they are interconnected, i.e., the microstructure, influences the performance of lithium-ion batteries. For batteries with high energy and power densities, the microstructure of the electrodes must be controlled during their manufacturing process. Moreover, understanding the microstructure helps in designing a high-performance, yet low-cost battery. In this study, we propose a systematic algorithm workflow for the images of the microstructure of anodes obtained from a focused ion beam scanning electron microscope (FIB-SEM). Here, we discuss the typical issues that arise in the raw FIB-SEM images and the corresponding preprocessing methods that resolve them. Next, we propose a Fourier transform-based filter that effectively reduces curtain artifacts. Also, we propose a simple, yet an effective, global-thresholding method to identify active materials and pores in the microstructure. Finally, we reconstruct the three-dimensional structures by concatenating the segmented images. The whole algorithm workflow used in this study is not fully automated and requires user interactions such as choosing the values of parameters and removing shine-through artifacts manually. However, it should be emphasized that the proposed global-thresholding method is deterministic and stable, which results in high segmentation performance for all sectioning images.
Nanocrystalline (NC) and ultrafine-grained (UFG) CoCrCuFeNi high-entropy alloy (HEA) with grain size ranging between 59 and 386 nm was produced via powder metallurgy and heat treatment. The as-sintered HEA exhibited two face-centered cubic (FCC) phases (CoCrFeNi-rich and Cu-rich phases) and a small grain size (59 nm), whereas the alloy after heat treatment at 1000 °C exhibited a CoCuFeNi-rich phase with FCC structure and relatively larger grain size (386 nm). Moreover, the yield strength decreased from 1930 to 883 MPa, and plastic strain to failure increased by 8–32%. In terms of microstructural evolution, grain boundary strengthening coupled with lattice distortion was the dominant strengthening mechanism for NC HEAs. Furthermore, the coefficient for boundary strengthening was higher in the HEAs than in the corresponding pure elemental metals with FCC structure, possibly because of significant lattice distortion. The UFG HEAs exhibited high strength and good ductility because of the activation of dislocation.
In Democratic People's Republic of Korea, only Plasmodium vivax malaria is prevalent, which is divided into two forms – long incubation form and short form. Among malaria cases reported in a year, long form accounts for 69% and short form 31%. Incubation period of short form ranges from 10 to 29 days (average 17 days) and long from 5·5 to 16 months (average 8–13 months). The most relapses (90%) were reported from May to September – malaria transmission season in the country. Result from preliminary mass chemoprevention in small size of population before transmission season to find appropriate method showed high protective efficacy in two regimens – one regimen given primaquine 0·25 mg base kg−1 day−1 for 14 days (95%) and another 0·5 mg base kg−1 day−1 for 7 days (94%). During the mass chemoprevention with primaquine, some adverse effects were reported but transient. We consider that mass chemoprevention with primaquine before transmission season is of great significance in disturbing the vivax malaria transmission, in which long incubation form is predominant in countries prevailing seasonal malaria.
This study aimed to investigate associations among spirituality, coping strategies, quality of life (QOL), and the effects of depression and anxiety thereon in cancer patients.
In total, 237 cancer patients referred to a psycho-oncology clinic at a university hospital in Korea were enrolled. After identifying predictors of patient QOL in a stepwise regression model, we developed a hypothetical path model wherein interpersonal coping was considered as a mediating variable between spirituality (meaning/peace) and QOL and wherein depression and anxiety affected each of these three variables.
The direct effect of spirituality (meaning/peace) on QOL was 36.7%. In an indirect model, interpersonal coping significantly mediated the relationship between spirituality (meaning/peace) and QOL. Depression exerted the largest negative effect on spirituality (meaning/peace), interpersonal coping, and QOL. Anxiety had negative effects on spirituality (meaning/peace) and QOL, but a positive effect on interpersonal coping.
Significance of results
Interpersonal coping strategies work as a partial mediator of the relationship between meaning/peace subscales of spirituality and QOL. Effective management of depression may help in achieving better outcomes associated therewith. Greater attention and efforts to improve social connectedness and meaning of life in spiritual well-being may improve the QOL of cancer patients.
The white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera, Delphacidae), has emerged as a serious rice pest in Asia. In the present study, 12 microsatellite markers were employed to investigate the genetic structure, diversity and migration route of 43 populations sampled from seven Asian countries (Bangladesh, China, Korea, Laos, Nepal, Thailand, and Vietnam). According to the isolation by distance analysis, a significant positive correlation was observed between genetic and geographic distances by the Mantel test (r2 = 0.4585, P = 0.01), indicating the role of geographic isolation in the genetic structure of S. furcifera. A population assignment test using the first-generation migrants detection method (thresholds a = 0.01) revealed southern China and northern Vietnam as the main sources of S. furcifera in Korea. Nepal and Bangladesh might be additional potential sources via interconnection with Vietnam populations. This paper provides useful data for the migration route and origin of S. furcifera in Korea and will contribute to planthopper resistance management.
Polymer composites of Polylactic acid (PLA) and poly-ε-caprolactone (PCL), containing small amounts of titanium oxide (TiO2) were developed for biomedical applications. These composite materials were prepared, and then printed using Fused Deposition Modeling (FDM). 3D printed structures were characterized to determine their mechanical properties and biocompatibility. DSC analysis yielded useful information regarding the immiscibility of the different polymers, and it was observed that the particles of TiO2 improved the stability of the polymers. The ultimate tensile strength and the fracture strain increased by adding TiO2 as a filler, resulting in values of approximately 45 MPa and 5.5 % elongation. The printed composites show excellent in vitro biocompatibility including cell proliferation and adhesion, and are therefore promising candidates to be used in the biomedical field for bone replacement procedures, due to their properties similar to those of cancellous bone.
Carbon-coated silicon nanowires (C-Si NWs) were prepared as anodes for lithium-ion batteries (LIBs). The C-Si NWs were synthesized using a simple and effective fabrication strategy via magnesiothermic reduction. The synthesis sequence of carbon coating before the chemical etching of the reduced Si NWs/MgO composite was found to be critical for improved battery performance. In addition, carbon coating was found to help to stabilize the solid electrolyte interphase layer during battery cycling, which is important to realize the benefits of Si-based LIBs. This synthesis method provides an efficient route to synthesizing high-performance Si electrodes via magnesiothermic reduction.
When a flat plate is withdrawn from a liquid pool, a liquid film is deposited on the plate. This simple process is called dip coating. In the case of vertically upward withdrawal, gravity competes with the surface tension and viscous drag, and the balance between those determine the meniscus shape and hence the film thickness. Most of the previous studies on dip coating assumed that the pool is sufficiently large so that the stationary container wall does not affect the film thickness. However, the cases where the stationary wall affects the entrained film have not been examined thoroughly so far. In this confined dip coating, the film thickness deviates from that of unconfined dip coating under the same conditions such as the withdrawal speed and the physical properties of the liquid. The meniscus in a confined pool is more curved than that in an unconfined pool owing to wetting on the stationary wall, which is parallel to the plate. Besides, a channel between the moving plate and the stationary wall appears; therefore, the flow inside the channel should be included in an analysis of confined dip coating. In the present study, we analyse the mechanism that determines the film thickness, both theoretically and numerically.
This study aimed to identify the effect of lateral neck dissection on voice change in thyroidectomised patients.
Medical records from 264 patients who underwent thyroidectomy with (n = 65) or without (n = 199) lateral neck dissection were reviewed. Clinical and voice evaluation data were compared between the two groups.
Patients who underwent surgery that included lateral neck dissection had lower fundamental frequencies and speaking fundamental frequencies. They also had a higher incidence of asymmetric mucosal wave and vocal fold oedema on videostroboscopy during the first month after surgery, with the incidence of vocal fold oedema remaining significantly higher at three months. Self-assessed voice quality scores were significantly higher in lateral neck dissection patients at both one and three months after surgery.
In thyroidectomised patients, lateral neck dissection lowers the vocal pitch in the initial period after surgery and induces vocal fold oedema that persists for several months. Although most objective parameters improved within a month, subjective symptoms lasted for longer.
Data from archaeology and paleoanthropology directly challenge the validity of the basic assumptions of the CLASH model. By not incorporating a “deep time” perspective, the hypothesis lacks the evolutionary baseline the authors seek to infer in validating the model.
Our objective was to evaluate long-term altered appearance, distress, and body image in posttreatment breast cancer patients and compare them with those of patients undergoing active treatment and with general population controls.
We conducted a cross-sectional survey between May and December of 2010. We studied 138 breast cancer patients undergoing active treatment and 128 posttreatment patients from 23 Korean hospitals and 315 age- and area-matched subjects drawn from the general population. Breast, hair, and skin changes, distress, and body image were assessed using visual analogue scales and the EORTC BR–23. Average levels of distress were compared across groups, and linear regression was utilized to identify the factors associated with body image.
Compared to active-treatment patients, posttreatment patients reported similar breast changes (6.6 vs. 6.2), hair loss (7.7 vs. 6.7), and skin changes (5.8 vs. 5.4), and both groups had significantly more severe changes than those of the general population controls (p < 0.01). For a similar level of altered appearance, however, breast cancer patients experienced significantly higher levels of distress than the general population. In multivariate analysis, patients with high altered appearance distress reported significantly poorer body image (–20.7, CI95% = –28.3 to –13.1) than patients with low distress.
Significance of results:
Posttreatment breast cancer patients experienced similar levels of altered appearance, distress, and body-image disturbance relative to patients undergoing active treatment but significantly higher distress and poorer body image than members of the general population. Healthcare professionals should acknowledge the possible long-term effects of altered appearance among breast cancer survivors and help them to manage the associated distress and psychological consequences.
This study investigates the relationship between insomnia and cognitive dysfunctions including, subjective memory impairment (SMI), mild cognitive impairment (MCI), and dementia, by considering depression in a community sample of elderly individuals.
Data for 1,740 elderly individuals aged 65 years and over were obtained from a nationwide dementia epidemiological study conducted in South Korea. Cognitive functional status was assessed by the Mini-Mental State Examination and the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet Clinical Assessment Battery. Insomnia was defined as the presence of at least one of the four sleep complaints (difficulty in initiating sleep, difficulty in maintaining sleep, early morning awakening, and non-restorative sleep), accompanied by moderate to severe daytime consequences. Depression was evaluated using the Geriatric Depression Scale.
The prevalence of insomnia in the patients with SMI, MCI, and dementia was found to be 23.2%, 19.6%, and 31.0%, respectively. The patients with SMI, MCI, and dementia were significantly more likely to have insomnia and the four sleep complaints than the normal comparison patients. After adjusting for sociodemographic factors, the significant relationships between cognitive dysfunctional status and insomnia remained. However, after adjusting for sociodemographic factors and depression, no significant relationships with any of the sleep complaints or insomnia remained.
Insomnia is a very common complaint in the elderly with SMI, MCI, and dementia. Depression might play an important factor in the relationship between insomnia and cognitive dysfunctional status in the elderly.
A new approach is proposed to analyze Bremsstrahlung X-rays that are emitted from laser-produced plasmas (LPP) and are measured by a stack type spectrometer. This new method is based on a spectral tomographic reconstruction concept with the variational principle for optimization, without referring to the electron energy distribution of a plasma. This approach is applied to the analysis of some experimental data obtained at a few major laser facilities to demonstrate the applicability of the method. Slope temperatures of X-rays from LPP are determined with a two-temperature model, showing different spectral characteristics of X-rays depending on laser properties used in the experiments.
Timed grammaticality judgment tests (TGJT) and oral elicited imitation tests (OEIT) are considered reliable and valid measures of implicit linguistic knowledge, but studies consistently observe better performances on the TGJT than the OEIT due to the different types of processing they require: comprehension for the TGJT and production for the OEIT. This study examines whether degree of access to implicit knowledge is a function of processing type. Results from a series of factor analyses suggest that the OEIT requires greater access to implicit knowledge—implying that it measures stronger implicit knowledge—than the TGJT. Furthermore, the study examines effects on construct validity of time pressure in the OEIT (uncontrolled vs. controlled) and modality in the TGJT (written vs. aural). The results indicate that the tests reached higher construct validity, or measured stronger implicit knowledge, when the OEIT employed controlled time pressure and the TGJT used aural stimuli.
Iron is an essential trace element that plays important roles in the cellular function of all organs and systems. However, the function of Fe(II) in mammalian embryo development is unknown. In this study, we investigated the role of Fe(II) during preimplantation embryo development. Depletion of Fe(II) using thiosemicarbazone-24 (TSC24), a specific Fe(II) chelator, rescued quenching of the Fe(II)-sensitive fluorophore phen green-SK. After in vitro fertilization, TSC24 significantly reduced the cleavage rate as well as blastocyst formation. The hatch rate of blastocysts was also reduced with 1 pM TSC24 treatment (20.25±1.86 versus 42.28±12.96%, p<0.05). Blastocysts were cultured in leukemia inhibitory factor-free mouse embryonic stem cell culture medium with or without TSC24, and those with depleted Fe(II) displayed delayed attachment and lost the ability to induce embryoid body formation. To further explore the mechanism of Fe(II) in embryo development, we assessed the expression of 5-hydroxymethylcytosine (5hmC) and OCT4 in the pronuclear and blastocyst stages, respectively. We observed that Fe(II) reduced 5hmC and OCT4 expression, which could be explained by low ten-eleven translocation (TET) enzyme activity induced by TSC24 treatment. These findings demonstrate that Fe(II) is required for mammalian embryo development and that it facilitates the process via regulation of TET activity.
In this paper we prove the local existence and uniqueness of C1+γ solutions of the Boussinesq equations with initial data υ0, θ0 ∈ C1+γ, ω0, ∇θ0 ∈ Lq for 0 < γ < 1 and 1 < q < 2. We also obtain a blow-up criterion for this local solutions. More precisely we show that the gradient of the passive scalar θ controls the breakdown of C1+γ solutions of the Boussinesq equations.
Human tissues are sophisticated ensembles of various cell types embedded in the complex but defined structures of the extracellular matrix (ECM). ECM is configured in a hierarchical structure from nano- to microscale, with many biological molecules forming large scale configurations and textures with feature sizes up to macroscopic scale (several hundred microns). The physicochemical, biological and mechanostructural properties of native ECM play a critical role in constructing a microenvironment for cells and tissues. In conjunction with the rapid evolution of material science and its fabrication techniques, studies of the topography and elasticity of ECM and other materials have allowed advanced interrogation of cellular mechanotransduction and cellular responses to mechanostructural cues. By learning from and mimicking the highly organized ECM structures found in vivo, topography-guided approaches to regulate cell function and fate have been widely investigated in the last several decades. Here, we review recent efforts in mimicking the micro- and nanotopography of the native ECM in vitro for the regulation of cellular behaviors. We also discuss how these biomimetic topographical surfaces have been applied to fundamental cell mechanobiology studies into cell adhesions, migrations, and differentiation as well as toward efforts in tissue engineering.