Fatigue Life Prediction under Random Loading Conditions in 7475-T7351 Aluminum Alloy using the RMS Model

ABSTRACT: This article is concerned with the fatigue life prediction in specimens of 7475-T7351 high strength aluminum alloy subjected to random fatigue loading. Fatigue life predictions are made using the root mean square model. This model is chosen because it has been defined as the most simple and effective one for fatigue life prediction in the components subjected to random loading by the authors of this article. The analysis procedure used in this study is relatively simple. The loading history for each specimen is analyzed to determine the root mean square maximum and minimum stresses and predictions are then made by assuming that the tests have been conducted under constant amplitude loading at the root mean square maximum and minimum stresses. The ratios of the predicted lives range from 3.22 to 1.52. These ratios are fairly good considering that the normal scatter in fatigue crack growth rates may range from a factor of two to four under identical load conditions. Moreover, an attempt has been made to improve prediction procedure using Forman's equation applied in the root mean square model. While using the improved prediction procedure, the ratios of the predicted lives range from 1.35 to 0.62 (e.g., error bound is reduced almost five times: from 222 to 48). Only relatively simple computer programs (Microsoft Excel for load history analysis and Mathematica for performing calculations) and a desktop computer are employed to make predictions. Improved prediction procedure allows more precise prediction of fatigue life as well as helps to obtain better prediction ratios but further experimental work should be performed to verify the validity of the attempt. KEY WORDS: 7475-T7351 aluminum alloy, RMS model, fatigue crack growth prediction under random loading, fatigue of materials

Increasing the Durability of Piezoelectric Impact-based Micro Wind Generator in Real Application

AbstractThe purpose of this study is to increase the durability of piezoelectric impact-based micro wind generator (PIMWG) in real application. Using new PIMWG design, numerical simulation, and experimental comparison analysis, we improved the durability of PIMWGs in real application. The experimental results show that the optimized PIMWG generated 2.4 mW (RMS value), and it did not crack within 40h. In this study, we improved the durability of PIMWGs for real application

Prevalence of sarcopenia and sarcopenic obesity in Korean adults: The Korean Sarcopenic Obesity Study (KSOS)

*Context:* Sarcopenic obesity (SO), a combination of excess weight and reduced muscle mass and/or strength, is suggested to be associated with an increased risk of adverse health outcomes. 
*Objectives:* To examine the prevalence and characteristics of Sarcopenic and SO defined by using different indices such as Appendicular Skeletal muscle Mass (ASM)/height^2^ and Skeletal Muscle Index (SMI (%): skeletal muscle mass (kg)/weight (kg) × 100) for Korean adults. 
*Methods:* 591 participants were recruited from the Korean Sarcopenic Obesity Study (KSOS) which is an ongoing prospective observational cohort study. Analysis was conducted in 526 participants (328 women, 198 men) who had complete data on body composition using Dual X-ray absorptiometry and computed tomography. 
*Results:* The prevalence of sarcopenia and SO increases with aging. Using two or more standard deviations (SD) of ASM/height^2^ below reference values from young, healthy adults as a definition of sarcopenia, the prevalence of sarcopenia and SO was 6.3% and 1.3% in men and 4.1% and 1.7% in women over 60 years of age. However, using two or more SD of SMI, the prevalence of sarcopenia and SO was 5.1% and 5.1% respectively in men and 14.2% and 12.5% respectively in women. As defined by SMI, subjects with SO had 3 times the risk of metabolic syndrome (OR = 3.03, 95% confidence interval (CI) = 1.26-7.26) and subjects with non-sarcopenic obesity had approximately 2 times the risk of metabolic syndrome (OR = 1.89, 95% CI = 1.18-3.02) compared with normal subjects. 
*Conclusion:* Obese subjects with relative sarcopenia were associated with a greater likelihood for metabolic syndrome. As Koreans were more obese and aging, the prevalence of SO and its impact on health outcomes are estimated to be rapidly grow. Further research is requested to establish the definition, cause and consequences of SO.
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Nontuberculous mycobacterial infection in a clinical presentation of Fitz-Hugh-Curtis syndrome: a case report with multigene diagnostic approach

BACKGROUND: Fitz-Hugh-Curtis syndrome (FHCS) is caused by inflammation of perihepatic capsules associated with pelvic inflammatory disease. In recent years, infections with nontuberculous mycobacteria (NTM) have been increasingly occurring in immunocompromised and immunocompetent patients. However, NTM has never been reported in patients with FHCS. We present the first case of a patient with extrapulmonary NTM infection in a clinical presentation of FHCS. CASE PRESENTATION: A 26-year-old Korean woman presented with right upper quadrant and suprapubic pain. She was initially suspected to have FHCS. However, she was refractory to conventional antibiotic therapy. Laparoscopy revealed multiple violin-string adhesions of the parietal peritoneum to the liver and miliary-like nodules on the peritoneal surfaces. Diagnosis of NTM was confirmed by the polymerase chain reaction analysis results of biopsy specimens that showed caseating granulomas with positive acid-fast bacilli. Treatment with anti-NTM medications was initiated, and the patient’s symptoms were considerably ameliorated. CONCLUSIONS: An awareness of NTM as potential pathogens, even in previously healthy adults, and efforts to exclude other confounding diseases are important to establish the diagnosis of NTM disease. NTM infection can cause various clinical manifestations, which in the present case, overlapped with the symptoms of perihepatic inflammation seen in FHCS

Enhanced Electrokinetic Transport of Sulfate in Saline Soil

The electrokinetic transport of sulfate was investigated as a means of treating and restoring a sulfate-accumulating saline soil. The electrokinetic treatment decreased the electrical conductivity of the soil, an indicator of soil salinity, to 58.6%, 73.1%, and 83.5% for 7, 14 and 21 days, respectively. More than 96% of the chloride and nitrate were removed within 7 days. However, the removal of sulfate was highly influenced by the anode material. An iron anode removed sulfate effectively, whereas, sulfate was hyper-accumulated in the anodic region when an inert anode was used. The iron anode was oxidized in a sacrificial anodic reaction, which competed with the electrolysis reaction of water at the anode, and finally the reaction prevented the severe acidification of the soil in the anodic region. However, the competing reactions produced hydrogen ions at the anode, and the ions were transported toward the cathode, which, in turn, acidified the soil, especially, in the anodic region. The acidification switched the surface charge of the soil from negative to positive, increasing the interaction between the soil surface and sulfate, and thus inhibiting the transport of sulfate under the electric field. The zeta potential analysis of the soil provided an explanation. The results indicate that preventing severe acidification is an important factor which influences the transport of anions and iron anode for the enhanced removal of anionic pollutants by electrokinetic remediation

Stepwise surface regeneration of electrochemical immunosensors working on biocatalyzed precipitation, Analyst 127

A new strategy of stepwise surface regeneration for electrochemical immunosensors, working on a biocatalyzed precipitation reaction, has been developed. The strategy is based on the combination of deposited product thin-film dissolution and bound-protein displacement reactions from the modified sensor surfaces. As a model system, surfaces functionalized with biotin groups and their affinity recognition/ displacement reactions with antibiotin antibody molecules were chosen and investigated for affinity-sensing and stepwise regeneration reactions

Oxygen Partial Pressure during Pulsed Laser Deposition: Deterministic Role on Thermodynamic Stability of Atomic Termination Sequence at SrRuO3/BaTiO3 Interface

With recent trends on miniaturizing oxide-based devices, the need for atomic-scale control of surface/interface structures by pulsed laser deposition (PLD) has increased. In particular, realizing uniform atomic termination at the surface/interface is highly desirable. However, a lack of understanding on the surface formation mechanism in PLD has limited a deliberate control of surface/interface atomic stacking sequences. Here, taking the prototypical SrRuO3/BaTiO3/SrRuO3 (SRO/BTO/SRO) heterostructure as a model system, we investigated the formation of different interfacial termination sequences (BaO-RuO2 or TiO2-SrO) with oxygen partial pressure (PO2) during PLD. We found that a uniform SrO-TiO2 termination sequence at the SRO/BTO interface can be achieved by lowering the PO2 to 5 mTorr, regardless of the total background gas pressure (Ptotal), growth mode, or growth rate. Our results indicate that the thermodynamic stability of the BTO surface at the low-energy kinetics stage of PLD can play an important role in surface/interface termination formation. This work paves the way for realizing termination engineering in functional oxide heterostructures.Comment: 27 pages, 6 figures, Supporting Informatio

Hemispheric asymmetry in hand preference of right-handers for passive vibrotactile perception: an fNIRS study

Hemispheric asymmetry in hand preference for passive cutaneous perception compared to active haptic perception is not well known. A functional near-infrared spectroscopy was used to evaluate the laterality of cortical facilitation when 31 normal right-handed participants were involved in 205 Hz passive vibrotactile cutaneous stimuli on their index fingers of preferred and less-preferred hand. Passive cutaneous perception resulted that preferred (right) hand stimulation was strongly leftward lateralized, whereas less-preferred (left) hand stimulation was less lateralized. This confirms that other manual haptic exploration studies described a higher hemispheric asymmetry in right-handers. Stronger cortical facilitation was found in the right primary somatosensory cortex (S1) and right somatosensory association area (SA) during left-hand stimulation but not right-hand stimulation. This finding suggests that the asymmetric activation in the S1 and SA for less-preferred (left) hand stimulation might contribute to considerably reinforce sensorimotor network just with passive vibrotactile cutaneous stimulation. © 2020, The Author(s).1