Simulation of deformation of layered sheet during micro powder imprinting process

This paper reports simulation of deformation during micro powder imprinting process, which is a newly developed process to form micro patterned surface on ceramic sheets. The process is proposed as a combined process of traditional hot-embossing and powder metallurgy. A compound sheet of powder material and polymer binder is pressed by a mold to be transcribed a micro-pattern on its surface. After pressing, the binder is removed by heating, and the sheet is sintered. Finally dense ceramic sheet with fine pattern can be obtained. This process can be used also for layered sheet of two different materials. By using this layered sheet, we can make a pattern not only on the surface of the upper layer but also along the interface between each layer. Of course, the same pattern with the mold’s shape can be transcribed on the surface, while, there can be found another micro pattern along the interface. These two patterns of the surface and the interface are useful to fabricate ceramic sheet with patterns on its both surfaces. For example, if a compound sheet was used as an upper layer and a pure organic sheet as a lower, the lower organic layer can act as a sacrificed layer. After debinding and sintering, only the upper layer remains, which has micro-patterns on the both sides. The shape of interface between layers can be controlled by changing properties of layers. It could be also influenced by the imprinting conditions, such as temperature and pressure. In order to design the shape of the interface, finite element analysis was employed in the present paper. Mooney-Rivlin’s deformation model was used to express deformation of materials during imprinting. In this paper, we compared the simulated results with experimental data to show effectiveness of the present simulation method

Anti-Apoptotic Effect of Chrysophanol Isolated from <i>Cassia tora</i> Seed Extract on Blue-Light-Induced A2E-Loaded Human Retinal Pigment Epithelial Cells

The seeds of Cassia tora (C. tora) species mainly contain anthraquinone, anthraquinone glycoside, and naphthalene derivatives. We investigated the anti-apoptotic effects of C. tora seed extract and its isolated compounds on blue-light-induced lipofuscin (A2E)-loaded human retinal pigment epithelial (RPE) cells. For analysis of the C. tora extract, high-performance liquid chromatography method was used. A2E-loaded human retinal pigment epithelial cells and blue light were used to create excessive photo-oxidation to induce cell death. Lactate dehydrogenase (LDH) assay was used to measure cell cytotoxicity, and the mRNA expression of genes involved in apoptosis was examined to evaluate the mechanism of cell death. C. tora extract, n-hexane fraction, and chrysophanol were found to inhibit apoptotic cell death. Additionally, C. tora extract, n-hexane fraction, and chrysophanol reduced the mRNA expression of genes involved in the apoptosis pathway. C. tora and chrysophanol were considered to inhibit apoptosis and oxidative stress response. The major component of C. tora has a protective effect against apoptosis. The ingredients of C. tora can be used as therapeutic substances or to prevent diseases caused by the excessive oxidation of A2E substances in the retina, such as in age-related macular degeneration

Automatic compensation enhances the orientation perception in chronic astigmatism

© 2022. The Author(s).Astigmatism is a prevalent optical problem in which two or more focal points blur the retinal image at a particular meridian. Although many features of astigmatic vision, including orientation perception, are impaired at the retinal image level, the visual system appears to partly restore perceptual impairment after an extended period of astigmatism. However, the mechanism of orientation perception restoration in chronic astigmatism has not yet been clarified. We investigated the notable reduction of perceptual error in chronic astigmatism by comparing the orientation perception of a chronic astigmatism group with the perception of a normal-vision group, in which astigmatism was transiently induced. We found that orientation perception in the chronic group was more accurate than in the normal vision group. Interestingly, the reduction of perceptual errors was automatic; it remained even after the optical refractive errors were fully corrected, and the orientation perception was much more stable across different orientations, despite the uneven noise levels of the retinal images across meridians. We provide here a mechanistic explanation for how the compensation of astigmatic orientation perception occurred, using neural adaptation to the biased distribution of orientations.11Nsciescopu

Simulation of deformation of layered sheet during micro powder imprinting process

This paper reports simulation of deformation during micro powder imprinting process, which is a newly developed process to form micro patterned surface on ceramic sheets. The process is proposed as a combined process of traditional hot-embossing and powder metallurgy. A compound sheet of powder material and polymer binder is pressed by a mold to be transcribed a micro-pattern on its surface. After pressing, the binder is removed by heating, and the sheet is sintered. Finally dense ceramic sheet with fine pattern can be obtained. This process can be used also for layered sheet of two different materials. By using this layered sheet, we can make a pattern not only on the surface of the upper layer but also along the interface between each layer. Of course, the same pattern with the mold’s shape can be transcribed on the surface, while, there can be found another micro pattern along the interface. These two patterns of the surface and the interface are useful to fabricate ceramic sheet with patterns on its both surfaces. For example, if a compound sheet was used as an upper layer and a pure organic sheet as a lower, the lower organic layer can act as a sacrificed layer. After debinding and sintering, only the upper layer remains, which has micro-patterns on the both sides. The shape of interface between layers can be controlled by changing properties of layers. It could be also influenced by the imprinting conditions, such as temperature and pressure. In order to design the shape of the interface, finite element analysis was employed in the present paper. Mooney-Rivlin’s deformation model was used to express deformation of materials during imprinting. In this paper, we compared the simulated results with experimental data to show effectiveness of the present simulation method

Induced astigmatism biases the orientation information represented in multivariate electroencephalogram activities

© 2021 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.A small physical change in the eye influences the entire neural information process along the visual pathway, causing perceptual errors and behavioral changes. Astigmatism, a refractive error in which visual images do not evenly focus on the retina, modulates visual perception, and the accompanying neural processes in the brain. However, studies on the neural representation of visual stimuli in astigmatism are scarce. We investigated the relationship between retinal input distortions and neural bias in astigmatism and how modulated neural information causes a perceptual error. We induced astigmatism by placing a cylindrical lens on the dominant eye of human participants, while they reported the orientations of the presented Gabor patches. The simultaneously recorded electroencephalogram activity revealed that stimulus orientation information estimated from the multivariate electroencephalogram activity was biased away from the neural representation of the astigmatic axis and predictive of behavioral bias. The representational neural dynamics underlying the perceptual error revealed the temporal state transition; it was transiently dynamic and unstable (approximately 350 ms from stimulus onset) that soon stabilized. The biased stimulus orientation information represented by the spatially distributed electroencephalogram activity mediated the distorted retinal images and biased orientation perception in induced astigmatism.11Nsciescopu

Introduction of Infection Prevention Tracheal Intubation Protocol during the COVID-19 Pandemic Is Not Associated with First-Pass Success Rates of Endotracheal Intubation in the Emergency Department: A Before-and-After Comparative Study

Aerosols and droplets have put healthcare workers performing airway management at high risk of contracting coronavirus disease 2019 (COVID-19). Experts have developed endotracheal intubation (ETI) guidelines and protocols to protect intubators from infection. We aimed to determine whether changes in the emergency department (ED) intubation protocol to prevent COVID-19 infection were associated with first-pass success (FPS) rates in ETI. We used data from the airway management registries in two academic EDs. The study was divided into pre-pandemic (January 2018 to January 2020) and pandemic (February 2020 to February 2022) periods. We selected 2476 intubation cases, including 1151 and 1325 cases recorded before and during the pandemic, respectively. During the pandemic, the FPS rate was 92.2%, which did not change significantly, and major complications increased slightly but not significantly compared with the pre-pandemic period. The OR for the FPS of applying infection prevention intubation protocols was 0.72 (p = 0.069) in a subgroup analysis, junior emergency physicians (PGY1 residents) had an FPS of less than 80% regardless of pandemic protocol implementation. The FPS rate of senior emergency physicians in physiologically difficult airways decreased significantly during the pandemic (98.0% to 88.5%). In conclusion, the FPS rate and complications for adult ETI performed by emergency physicians using COVID-19 infection prevention intubation protocols were similar to pre-pandemic conditions

Development and validation of a scoring system for mortality prediction and application of standardized W statistics to assess the performance of emergency departments

Abstract Background In-hospital mortality and short-term mortality are indicators that are commonly used to evaluate the outcome of emergency department (ED) treatment. Although several scoring systems and machine learning-based approaches have been suggested to grade the severity of the condition of ED patients, methods for comparing severity-adjusted mortality in general ED patients between different systems have yet to be developed. The aim of the present study was to develop a scoring system to predict mortality in ED patients using data collected at the initial evaluation and to validate the usefulness of the scoring system for comparing severity-adjusted mortality between institutions with different severity distributions. Methods The study was based on the registry of the National Emergency Department Information System, which is maintained by the National Emergency Medical Center of the Republic of Korea. Data from 2016 were used to construct the prediction model, and data from 2017 were used for validation. Logistic regression was used to build the mortality prediction model. Receiver operating characteristic curves were used to evaluate the performance of the prediction model. We calculated the standardized W statistic and its 95% confidence intervals using the newly developed mortality prediction model. Results The area under the receiver operating characteristic curve of the developed scoring system for the prediction of mortality was 0.883 (95% confidence interval [CI]: 0.882–0.884). The Ws score calculated from the 2016 dataset was 0.000 (95% CI: − 0.021 – 0.021). The Ws score calculated from the 2017 dataset was 0.049 (95% CI: 0.030–0.069). Conclusions The scoring system developed in the present study utilizing the parameters gathered in initial ED evaluations has acceptable performance for the prediction of in-hospital mortality. Standardized W statistics based on this scoring system can be used to compare the performance of an ED with the reference data or with the performance of other institutions

The Prognostic Value of Optic Nerve Sheath Diameter/Eyeball Transverse Diameter Ratio in the Neurological Outcomes of Out-of-Hospital Cardiac Arrest Patients

Background and objectives: The optic nerve sheath diameter (ONSD) is indicative of elevated intracranial pressure. However, the usefulness of the ONSD for predicting neurologic outcomes in cardiac arrest survivals has been debatable. Reportedly, the ONSD/eyeball transverse diameter (ETD) ratio is a more reliable marker for identifying intracranial pressure than sole use of ONSD. Materials and Methods: This retrospective study aimed to investigate the prognostic value of the ONSD/ETD ratio in out-of-hospital cardiac arrest (OHCA) patients. We studied the brain computed tomography scans of adult OHCA patients with return of spontaneous circulation, who visited a single hospital connected with a Korean university between January 2015 and September 2020. We collected baseline characteristics and patient information from electronic medical records and ONSD and ETD were measured by two physicians with a pre-defined protocol. According to their neurologic outcome upon hospital discharge, patients were divided into good neurologic outcome (GNO; cerebral performance category [CPC] 1&ndash;2) and poor neurologic outcome (PNO; CPC 3&ndash;5) groups. We evaluated the ONSD/ETD ratio between the GNO and PNO groups to establish its prognostic value for neurologic outcomes. Results: Of the 100 included patients, 28 had GNO. Both the ONSD and ETD were not significantly different between the two groups (ONSD, 5.48 mm vs. 5.66 mm, p = 0.054; ETD, 22.98 mm vs. 22.61 mm, p = 0.204). However, the ONSD/ETD ratio was significantly higher in the PNO group in the univariate analysis (0.239 vs. 0.255, p = 0.014). The area under the receiver operating characteristic curve of ONSD/ETD ratio for predicting PNO was 0.66 (95% confidence interval, 0.56&ndash;0.75; p = 0.006). There was no independent relationship between the ONSD/ETD ratio and PNO in multivariate analysis (aOR = 0.000; p = 0.173). Conclusions: The ONSD/ETD ratio was more reliable than sole use of ONSD and might be used to predict neurologic outcomes in OHCA survivors

Endotracheal Intubation Using a Direct Laryngoscope and the Protective Performances of Respirators: A Randomized Trial

Purpose. Emergency physicians are at risk for infection during invasive procedures, and the respirators can reduce this risk. This study aimed to determine whether endotracheal intubation using direct laryngoscopes affected protection performances of respirators. Methods. A randomized crossover study of 24 emergency physicians was performed. We performed quantitative fit tests using respirators (cup type, fold type without a valve, and fold type with a valve) before and during intubation. The primary outcome was respirators’ fit factors (FF), and secondary outcomes were acceptable protection (percentage of scores above 100 FF [FF%]). Results. 24 pieces of data were analyzed. Compared to fold-type respirator without a valve, FF and FF% values were lower when participants wore a cup-type respirator (200 FF [200-200] versus 200 FF [102.75–200], 100% [78.61–100] versus 74.16% [36.1–98.9]; all P<0.05) or fold-type respirator with a valve (200 FF [200-200] versus 142.5 FF [63.50–200], 100% [76.10–100] versus 62.50% [8.13–100]; all P<0.05). There were no significant differences in intubation time and success rate according to respirator types. Conclusions. Motion during endotracheal intubation using direct laryngoscopes influenced the protective performance of some respirators. Therefore, emergency physicians should identify and wear respirators that provide the best personalized fit for intended tasks