Adrenocorticotropic hormone and ß-endorphin concentration as a prognostic factor in patients with subarachnoid hemorrhage due to aneurysmal rupture.

OBJECTIVE: Adrenocorticotropic hormone (ACTH) and ß-endorphin are pituitary neuro-peptides released by acute stress. We determined why the prognosis of patients with subarachnoid hemorrhages (SAH) due to aneurysmal rupture is not always dependent on the Hunt-Hess grading system (HHS) and delta-National Institutes of Health Stroke Scale (NIHSS), while studying endogenous neuropeptides, including ACTH and ß-endorphin. METHODS: We analyzed blood samples collected from patients with SAH (SAH group; n=37) and those with unruptured intracranial aneurysms (control group; n=37). Blood sampling was performed before any procedure or chemical agents administration. The results of ACTH and ß-endorphin measurements were compared using the delta-NIHSS and HHS. The data were analyzed using descriptive statistics, independent samples t-tests, and Pearson's correlations. RESULTS: Of the 18 patients with low-grade HHS, 13 had low delta-NIHSS and five showed high delta-NIHSS. Of the 19 patients with high-grade HHS, the delta-NIHSS was ≥14 in the other five patients. ACTH concentration was high (497.3 pg/mL) in five patients with high-grade HHS and high delta-NIHSS. ß-endorphin concentration was high (159.7 pg/mL) in 13 patients with low-grade HHS and low delta-NIHSS. CONCLUSIONS: High ACTH levels in patients with massive bleeding and poor neurological status suggests increasing ACTH secretion in response to bleeding stress, which may aggravate neurological status. Contrary to ACTH, high ß-endorphin levels in patients with low-grade HHS implied the involvement of additional factors in predicting fair outcomes related to low delta-NIHSS. These results may provide insight into the varying prognostic potential of HHS in SAH patients.

The influence of hydrogen concentration in amorphous carbon films on mechanical properties and fluorine penetration: a density functional theory and ab initio molecular dynamics study.

Amorphous carbon (a-C) films have attracted significant attention due to their reliable structures and superior mechanical, chemical and electronic properties, making them a strong candidate as an etch hard mask material for the fabrication of future integrated semiconductor devices. Density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations were performed to investigate the energetics, structure, and mechanical properties of the a-C films with an increasing sp3 content by adjusting the atomic density or hydrogen content. A drastic increase in the bulk modulus is observed by increasing the atomic density of the a-C films, which suggests that it would be difficult for the films hardened by high atomic density to relieve the stress of the individual layers within the overall stack in integrated semiconductor devices. However, the addition of hydrogen into the a-C films has little effect on increasing the bulk modulus even though the sp3 content increases. For the F blocking nature, the change in the sp3 content by both atomic density and H concentration makes the diffusion barrier against the F atom even higher and suppresses the F diffusion, indicating that the F atom would follow the diffusion path passing through the sp2 carbon and not the sp3 carbon due to the significantly high barrier. For the material design of a-C films with adequate doped characteristics, our results can provide a new straightforward strategy to tailor the a-C films with excellent mechanical and other novel physical and chemical properties.

First principles investigation on energetics, structure, and mechanical properties of amorphous carbon films doped with B, N, and Cl.

Amorphous carbon (a-C) films have received significant attention due to their reliable structures and superior mechanical, chemical and electronic properties, making them a strong candidate as a hard mask material. We investigated the energetics, structure, and electronic and mechanical properties of the B, N, and Cl doped a-C films based on density functional theory (DFT) calculation. Our DFT calculated results clearly show that introducing B and N atoms into a-C films makes the bulk modulus slightly reduced as a function of the concentration increases. Interestingly, it is noted that introducing Cl atom into a-C films makes the bulk modulus is drastically reduced, which suggests that the films softened by Cl doping would relieve residual stress of the individual layers within the overall stacks in integrated semiconductor devices. These requirements become more important and increasingly more challenging to meet as the device integrity grows. In the perspective of F blocking nature, B doping into a-C films pulls in and captures the F atom due to the strong bonding nature of B‒F bond than C-F bond. Unlike the B doping, for the N doped a-C film, F atom has extremely large diffusion barrier of 4.92 eV. This large diffusion barrier is attributed to the electrostatically repulsive force between both atoms. The Cl doped a-C film shows consistently the similar results with the N doped a-C film because both N and Cl atoms have large electro-negativity, which causes F atom to push out. If one notes the optimized designing with the suitable doped characteristics, our results could provide a new straightforward strategy to tailor the a-C films with excellent mechanical and other novel physical and chemical properties.

Early Phase of Achalasia Manifested as an Esophageal Subepithelial Tumor.

The Chicago classification (CC) defines an esophagogastric junction outflow obstruction (EGJOO) as the presence of several instances of intact or weak peristalsis, elevated median integrated relaxation pressure above 15 mmHg, and a discrepancy from the criteria of achalasia. The revised CC addresses the potential etiology of EGJOO, including the early forms of achalasia, mechanical obstruction, esophageal wall stiffness, or manifestation of hiatal hernia. A 58-year-old woman visited the Presbyterian Medical Center with swallowing difficulty. The patient underwent a high resolution manometry (HRM) examination and was diagnosed with EGJOO. Chest CT was performed to exclude a mechanical obstruction as a cause, and CT revealed a subepithelial tumor (SET) at the upper part of the esophagogastric junction. Therefore, laparoscopic surgery was performed and eccentric muscular hypertrophy of the distal esophagus was observed. Longitudinal myotomy and Dor fundoplication were also performed. The histology findings of the surgical specimens were consistent with achalasia. This paper reports a case of early achalasia that was finally diagnosed by the histology findings, but was initially diagnosed as EGJOO using HRM and misdiagnosed as SET in the image study.

Overall reaction mechanism for a full atomic layer deposition cycle of W films on TiN surfaces: first-principles study.

We investigated the overall ALD reaction mechanism for W deposition on TiN surfaces based on DFT calculation as well as the detailed dissociative reactions of WF6. Our calculated results suggest that the overall reactions of the WF6 on the B-covered TiN surfaces are energetically much more favorable than the one on the TiN surfaces, which means that the high reactivity of WF6 with the B-covered TiN surface is attributed to the presence of B-covered surface made by B2H6 molecules. As a result, an effect of the B2H6 flow serves as a catalyst to decompose WF6 molecules. Two additional reaction processes right after WF6 bond dissociation, such as W substitution and BF3 desorption, were also explored to clearly understand the detailed reactions that can occur by WF6 flow. At the first additional reaction process, W atoms can be substituted into B site and covered on the TiN surfaces due to the stronger bonding nature of W with the TiN surface than B atoms. At the second additional reaction process, remaining atoms, such as B and F, can be easily desorbed as by-product, that is, BF3 because BF3 desorption is an energetically favorable reaction with a low activation energy. Furthermore, we also investigated the effect of H2 post-treatment on W-covered TiN surface in order to remove residual F adatoms, which are known to cause severe problems that extremely degrade the characteristics of memory devices. It was found that both H2 dissociative reaction and HF desorption can occur sufficiently well under somewhat high temperature and H2 ambience, which is confirmed by our DFT results and previously reported experimental results. These results imply that the understanding of the role of gas molecules used for W deposition gives us insight into improving the W ALD process for future memory devices.