Identification of Novel Nucleocapsid Chimeric Proteins Inhibiting HIV-1 Replication.

The positive transcription elongation factor b (P-TEFb) is an essential factor that induces transcription elongation and is also negatively regulated by the cellular factor HEXIM1. Previously, the chimeric protein HEXIM1-Tat (HT) was demonstrated to inhibit human immunodeficiency virus-1 (HIV)-1 transcription. In this study, we attempted to develop an improved antiviral protein that specifically binds viral RNA (vRNA) by fusing HT to HIV-1 nucleocapsid (NC). Thus, we synthesized NC-HEXIM1-Tat (NHT) and HEXIM1-Tat-NC (HTN). NHT and HTN inhibited virus proliferation more effectively than HT, and they did not attenuate the function of HT. Notably, NHT and HTN inhibited the infectivity of the progeny virus, whereas HT had no such effect. NHT and HTN selectively and effectively interacted with vRNA and inhibited the proper packaging of the HIV-1 genome. Taken together, our results illustrated that the novel NC-fused chimeric proteins NHT and HTN display novel mechanisms of anti-HIV effects by inhibiting both HIV-1 transcription and packaging.

Dynamic Behavior of a Nanosized Water Droplet on the Stepped Surface with a Wetting Gradient.

The present study investigated the dynamic behavior of a nanosized water droplet on a flat and stepped surface using molecular dynamics simulations. The effects of a wetting gradient associated with the surface and the step height of a stepped surface on the dynamic behavior of the water droplet were considered in this study. The dynamic behaviors of the water droplet were described quantitatively upon analyzing the transient variation of the adhesion energy and the position of the water droplet along with the time required to climb the step. The water droplet moved smoothly along the surface with an increasing wetting gradient. On the other hand, the step obstructed the water droplet from climbing the step as the step height increases. The dynamic behavior of the water droplet depending on the variation of the normalized step height and the differences in adhesion energies between the different surfaces was classified into three types, namely, (1) fully climbing the step, (2) partially climbing the step, and (3) being blocked by the step. In the case in which the water droplet fully climbs the step, the time taken for the water droplet to fully climb the step showed a non-monotonic pattern as the step height increases.

Wetting Behavior of a Surface with Dual-Scale Structures.

Theoretical and numerical studies were conducted to investigate the transitional interpillar spacing for dual-scale structures, where wetting transition between the Wenzel and Cassie-Baxter states occurs in the primary and secondary pillars. A theoretical formula was derived for the transitional interpillar spacing based on the continuum picture of water. Molecular dynamics (MD) simulations were carried out by varying the interpillar spacing for the primary pillars for single- and dual-scale structures with various pillar heights. The results obtained from the theoretical formula agreed reasonably well with the results obtained from MD simulations, especially when the primary pillar height was relatively high. The transitional interpillar spacing increases as the pillar height and the number of secondary pillars increase. The effect of the secondary pillars on the transitional interpillar spacing was also evaluated using the difference in the grand potentials between the Wenzel and Cassie-Baxter states. These results show that the dual-scale structures increase the transitional interpillar spacing with an increase in the surface hydrophobicity.

Development of a Stereotactic Radiosurgery Frame Adapter for a Multichannel MRI Coil.

BACKGROUND: The usage of multichannel brain MRI coils, which have several advantages over single-channel brain coils used for stereotactic radiosurgery (SRS), requires a frame adapter device to fit the frames inside the multichannel brain coils. However, such a frame adapter has not been developed until now. OBJECTIVE: to develop an SRS frame adapter for multichannel MRI coils and verify the geometrical accuracy and signal-to-noise ratio (SNR) of the MR images obtained using multichannel MRI coils. METHODS: We fabricated an SRS frame adapter for a 48-channel MRI coil using a three-dimensional (3D) printer. Furthermore, we obtained phantom and human-brain MR images with a 3.0 Tesla MRI scanner using multi- and single-channel coils. Computed tomography (CT) phantom images were also obtained as reference. We compared the coordinate errors of the multi- and single-channel coils to evaluate the geometrical accuracy. Two neurosurgeons measured the coordinates. In addition, we compared the SNR differences between multi- and single-channel coils using the T1- and T2-weighted brain images. RESULTS: For the CT coordinate measurements, the correlation coefficient r = 1 and p < 0.001 with respect to the 3 axes (Δx, Δy, and Δz) and 3D errors (Δr) showed no interpersonal differences between the 2 neurosurgeons. The results obtained using the T1-weighted images showed that a multichannel coil had smaller coordinate errors in Δx, Δy, Δz, and Δr than that observed in case of a single-channel coil (p < 0.001). In case of the SNR measurements, most of the brain areas showed higher SNRs when using a multichannel coil compared with that observed when using a single-channel coil in the T1- and T2-weighted images. CONCLUSION: Compared with single-channel coils, the use of multichannel MRI coils with a newly developed frame adapter is expected to ensure successful SRS treatments with improved geometrical accuracy and SNR.

Clinical significance of vitamin D in idiopathic normal pressure hydrocephalus.

BACKGROUND: Although recent studies show vitamin D deficiency is associated with cognitive decline, urinary incontinence, and gait instability, there has been no study on the effect of vitamin D on idiopathic normal pressure hydrocephalus (iNPH) characterized by the classic symptom triad of cognitive decline, urinary incontinence, and gait instability. We investigated the clinical significance of vitamin D in patients with iNPH. METHODS: Between 2017 and 2020, 44 patients who underwent ventriculoperitoneal shunt surgery were divided into low (< 15 ng/mL) and high (≥ 15 ng/mL) vitamin D groups according to the concentration of 25(OH)D, an effective indicator of vitamin D status. They were respectively evaluated according to clinical and radiological findings. RESULTS: The low vitamin D group (n = 24) showed lower preoperative cognition compared to the high vitamin D group (n = 20) in terms of Korean-Mini Mental Status Examination (K-MMSE) and iNPH grading scale (iNPHGS) (K-MMSE: 20.5 ± 5.4 versus 24.0 ± 4.5, p = 0.041; iNPHGS cognitive score: 2 ± 0.9 versus 1 ± 0.6, p = 0.025). And the low vitamin D group showed pre- and postoperatively more severe urinary incontinence (preoperative iNPHGS urinary score: 1 ± 1.0 versus 0 ± 0.9, p = 0.012; postoperative iNPHGS urinary score:1 ± 1.0 versus 0 ± 0.9, p = 0.014). The score of narrow high-convexity sulci for the low vitamin D group was lower (low vitamin D group: 1 ± 0.7 versus high vitamin D group: 2 ± 0.4, p = 0.031). CONCLUSION: Lower concentration of vitamin D in iNPH may be related to lower preoperative cognition, pre- and postoperative urinary incontinence, and brain morphological change.

Evaluation of the Interaction between Bax and Hsp70 in Cells by Using a FRET System Consisting of a Fluorescent Amino Acid and YFP as a FRET Pair.

To gain insight into factors that lead to dissociation of Bax from a complex with Hsp70 during apoptosis, we recently constructed a fluorescence resonance energy transfer (FRET) system composed of the Hsp70-YFP (YFP=yellow fluorescent protein) fusion protein and fluorescent amino acid (ANAP=6-acetyl(naphthalen-2-ylamino)-2-aminopropanoic acid)-containing Bax (Bax-ANAP), which was produced by using the genetic code expansion technique. In the current study, the FRET system was employed to elucidate how brefeldin A (an endoplasmic reticulum stress inducer), chlorpromazine and apoptozole (lysosomal membrane destabilizers), bafilomycin A1 (an inhibitor of lysosomal acidification) as well as raptinal and Az-TPP-O3 (mitochondria-targeted apoptosis inducers) affect the interaction between Bax and Hsp70. Analyses of single live cell images together with results of co-immunoprecipitation assays reveal that brefeldin A, chlorpromazine, and apoptozole promote dissociation of the Bax/Hsp70 complex through activation of the activator BH3-only protein. However, the results show that bafilomycin A1, raptinal, and Az-TPP-O3 have no influence on the interaction of Bax with Hsp70. The combined observations made in the current and previous studies demonstrate that the FRET system consisting of Bax-ANAP and Hsp70-YFP is highly useful to understand apoptotic processes associated with the Bax-Hsp70 interaction.

Analysis of Protein-Protein Interaction in a Single Live Cell by Using a FRET System Based on Genetic Code Expansion Technology.

Hsp70 is known to directly bind to Bax for suppression of apoptosis. However, mechanisms on how Bax is dissociated from its complex with Hsp70 during apoptosis remain largely unknown. In the current study, we developed the efficient fluorescence resonance energy transfer (FRET) system which consisted of Hsp70-YFP and fluorescent amino acid (ANAP)-incorporated Bax, which was generated by using genetic code expansion technology, and applied the FRET system to elucidate mechanisms on how apoptosis-inducing substances dissociate Bax from Hsp70. Time-dependent analysis of single live cell images showed that Bax activators binding to Bax trigger sites inhibited the Bax-Hsp70 interaction but a Bax activator, which blocks phosphorylation of S184 via binding to the C-terminal S184 site, did not affect this interaction. Additionally, an inhibitor for Hsp70-Hsp40 interaction blocked the Bax-Hsp70 interaction. Furthermore, p53 activators promoted the dissociation of Bax from Hsp70 by reactivating p53 which disrupted the Bax-Hsp70 interaction. We also found that death ligands and a Bcl-2 inhibitor enhanced the dissociation of Bax from Hsp70 by activating activator BH3-only proteins. Results from this effort suggest that FRET systems consisting of the ANAP-incorporated protein and the YFP fusion protein will be valuable tools to gain an understanding of other types of protein-protein interactions.

Progressively enlarging childhood chronic subdural hematoma surgically treated 26 years after diagnosis.

Pediatric chronic subdural hematoma (CSDH) is a relatively common disorder. Treatment often requires burr hole drainage or subduroperitoneal shunt placement; some patients are managed conservatively. However, the long-term outcome of untreated pediatric CSDH is unknown. The authors report a case of a huge, progressively enlarging subdural granuloma that was surgically treated 26 years after the initial diagnosis of CSDH. This 30-year-old male patient presented with worsening intermittent atonic seizure-like movements, which had been noted since he was 4 years old. At that time, the patient was diagnosed with CSDH at an outside hospital, but an operation was refused by the parents. Magnetic resonance imaging (MRI) performed at 23 years of age showed a huge subdural mass on the right frontoparietal region and a smaller mass on the left side with a significant midline shift. Upon presentation at the age of 30, MRI revealed worsening of the right subdural mass and midline shift. Subsequently, the patient underwent craniotomy and subtotal removal of the mass and capsule. The volume of the content was approximately 430 cc. Untreated pediatric CSDH can grow progressively, even over several decades. Patients with CSDH, especially those managed conservatively, should be closely monitored for worsening symptoms over a long-term follow-up period.

Serial measurement of S100B and NSE in pediatric traumatic brain injury.

PURPOSE: Increased serum biomakers, such as S100 calcium-binding protein B (S100B) and neuron-specific enolase (NSE), are associated with traumatic brain injury (TBI). The purpose of this study is to investigate the serum levels of S100B and NSE in pediatric TBI patients and to predict a clinical outcome. METHODS: Peripheral venous blood was collected within 6 h of injury and at 1 week to measure S100B and NSE. The serum S100B and NSE levels were measured using commercially available enzyme-linked immunosorbent assay kits. The authors divided participants into two groups at admission: a favorable group (patients with Glasgow Coma Scale [GCS] scores of 10-15) and an unfavorable group (patients with GCS scores of less than 9). Both S100B and NSE levels were compared between the two groups at the time of admission and 1 week later. RESULTS: Ten pediatric patients were enrolled (5 in the favorable group, 5 in the unfavorable group). The median serum S100B level of 134.21 pg/ml (range, 51.00-789.65 pg/ml) in patients with TBI at admission dropped to 41.49 pg/ml (range, 25.65-260.93 pg/ml) after 1 week, with significant differences between the traumatic event and 1 week later (p = 0.007). The median serum NSE level of 14.76 ng/ml (range, 6.48-21.23 ng/ml) in patients with TBI at admission was higher than that after 1 week (4.96 ng/ml, range, 3.01-31.21 ng/ml), with significant differences (p = 0.015). A significant difference was observed in S100B after 1 week between patients in the favorable and unfavorable groups (p = 0.047). One patient whose serum S100B and NSE levels were elevated 1 week after TBI eventually died. CONCLUSIONS: Elevated serum S100B and NSE levels in pediatric TBI patients decreased 1 week after traumatic events. The serum S100B level 1 week after TBI was related to the severity of brain damage. These results indicated that serum S100B and NSE might play a role in predicting the prognosis and monitoring ongoing brain injury in pediatric TBI patients.

Carbohydrate Analogue Microarrays for Identification of Lectin-Selective Ligands.

Fifty-five mono- and disaccharide analogues were prepared and used for the construction of microarrays to uncover lectin-selective ligands. The microarray study showed that two disaccharide analogues, 28' and 44', selectively bind to Solanum tuberosum lectin (STL) and wheat germ agglutinin (WGA), respectively. Cell studies indicated that 28' and 44' selectively block the binding of STL and WGA to mammalian cells, unlike the natural ligand LacNAc, which suppresses binding of both STL and WGA to cells.

Stereotactic radiosurgery for intracranial dural arteriovenous fistulas: its clinical and angiographic perspectives.

BACKGROUND: To assess the efficacy of stereotactic radiosurgery (SRS) for intracranial dural arteriovenous fistulas (DAVFs), the authors retrospectively reviewed our 7-year experience. We evaluated the obliteration rate, improvement in clinical symptoms, and complications. METHODS: Thirty patients with DAVF underwent SRS using a Gamma Knife between 2009 and 2015. Twenty-three patients were treated with SRS alone, and seven patients underwent SRS for residual or recurrent DAVFs after embolization or surgery. Chemosis, diplopia, and pulsating tinnitus were the most common symptoms. Median target volume was 2.9 cm3 (range, 0.8-13.6 cm3), and median radiation dose to the target was 17 Gy (range, 12-20 Gy). Median follow-up period was 33 months (range, 6-82 months). RESULTS: At the last neuroimaging follow-up, DAVFs were totally obliterated in 23 patients (77%) and subtotally in 7 (23%). At the last clinical follow-up, 21 patients (70%) showed complete recovery, and 9 (30%) showed incomplete recovery in symptoms or signs. None experienced worsening symptoms or signs. Asymptomatic perilesional edema after SRS occurred in one patient (3%). Total obliteration rates after SRS were 43% at 1 year, 79% at 2 years, and 95% at 5 years. Improvement rates of neurological function after SRS were 12% at 1 month, 52% at 2 months, 72% at 3 months, and 96% at 6 months. A multivariate analysis revealed that Borden type 1 (p = 0.019, hazard ratio, 3.254, 95% confidence interval, 1.216-8.707) was significantly associated with symptom improvement. CONCLUSIONS: SRS for intracranial DAVFs provided a high obliteration rate and a relatively low risk of radiation-induced complications. In selected benign cases without cortical venous drainage, SRS is a safe and effective treatment for symptom relief and fistula obliteration, even though the time course of improvement is longer than those of embolization and surgery.

Screening of Pre-miRNA-155 Binding Peptides for Apoptosis Inducing Activity Using Peptide Microarrays.

MicroRNA-155, one of the most potent miRNAs that suppress apoptosis in human cancer, is overexpressed in numerous cancers, and it displays oncogenic activity. Peptide microarrays, constructed by immobilizing 185 peptides containing the C-terminal hydrazide onto epoxide-derivatized glass slides, were employed to evaluate peptide binding properties of pre-miRNA-155 and to identify its binding peptides. Two peptides, which were identified based on the results of peptide microarray and in vitro Dicer inhibition studies, were found to inhibit generation of mature miRNA-155 catalyzed by Dicer and to enhance expression of miRNA-155 target genes in cells. In addition, the results of cell experiments indicate that peptide inhibitors promote apoptotic cell death via a caspase-dependent pathway. Finally, observations made in NMR and molecular modeling studies suggest that a peptide inhibitor preferentially binds to the upper bulge and apical stem-loop region of pre-miRNA-155, thereby suppressing Dicer-mediated miRNA-155 processing.

The clinical significance of fascin expression in a newly diagnosed primary glioblastoma.

The actin-binding protein fascin has been associated with clinically aggressive tumors and poor prognosis. The purpose of this study was to investigate possibility of fascin expression as a prognostic factor in a newly diagnosed primary glioblastoma (GBM). Between July 2007 and December 2013, 37 out of 126 patients diagnosed with GBM satisfied the following inclusion criteria: (1) the presence of immunohistochemically-available tissue, (2) a new primary GBM, (3) gross-total resection, and (4) standardized adjuvant treatment, known as the Stupp regimen. The median follow-up period was 18 months (range 5-95). According to the staining intensity of fascin, progression-free survival (PFS) in the low-intensity fascin group (median PFS 9.0 months; 95 % CI 6.0-12.0) was longer than PFS in the high-intensity fascin group (median PFS 7.0 months; 95 % CI 5.6-10.4; p = 0.024). Overall survival (OS) in the low-intensity fascin group (median OS 20.0 months; 95 % CI 17.7-22.4) was longer than OS in the high-intensity fascin group (median OS 13.0 months; 95 % CI 8.2-17.8; p = 0.031). And, the staining intensity of fascin was a statistically significant factor in PFS and OS according to univariate and multivariate analyses (univariate analysis p = 0.043 and p = 0.043; multivariate analysis p = 0.041 and p = 0.044). Our clinical study showed that fascin expression intensity may be correlated with clinical outcomes of a newly diagnosed primary GBM, especially with regard to PFS and OS.

The efficacy of gamma knife radiosurgery alone as a primary treatment for intracranial dural arteriovenous fistulas.

BACKGROUND: The application of gamma knife radiosurgery (GKRS) alone has been expanded for dural arteriovenous fistulas (DAVFs). However, a standardized protocol delineating the appropriate circumstances for GKRS alone in cases of DAVF has yet to be determined. The purpose of this study was to report a single center's treatment algorithm for GKRS alone as a primary treatment for intracranial DAVFs and assess related clinical and radiological data. METHOD: Among 31 DAVF patients treated according to our institute's treatment algorithm between February 2009 and November 2014, 20 patients underwent GKRS alone. DAVF patients treated with GKRS alone fell in two main subgroups: DAVF patients without cortical venous reflux (CVR) but with symptoms (n = 8) and DAVF patients with CVR but without a high bleeding risk (defined as CVR with aggressive symptoms including hemorrhage or non-hemorrhagic neurological deficit, n = 11). One DAVF patient with a high bleeding risk had GKRS alone because of difficult endovascular access. Mean radiation volume was 4.8 cc (range, 0.7-14.2 cc), and mean maximal dose was 33.5 Gy (range, 28-38 Gy). RESULTS: At mean follow-up of 29.1 months (range, 8-69 months), radiological findings demonstrated complete cures in 18 patients (90 %) and subtotal cures in 2 patients (10 %). One patient had a transient complication, but no neurologic sign. All symptomatic patients showed complete resolution. CONCLUSIONS: Our treatment algorithm showed GKRS alone may serve as a primary treatment for patients with DAVFs regardless of location and presence of CVR, unless there is a high bleeding risk. However, a multicenter, prospective study is necessary to generalize our treatment algorithm.

Probing cell-surface carbohydrate binding proteins with dual-modal glycan-conjugated nanoparticles.

Dual-modal fluorescent magnetic glyconanoparticles have been prepared and shown to be powerful in probing lectins displayed on pathogenic and mammalian cell surfaces. Blood group H1- and Le(b)-conjugated nanoparticles were found to bind to BabA displaying Helicobacter pylori, and Le(a)- and Le(b)-modified nanoparticles are both recognized by and internalized into DC-SIGN and SIGN-R1 expressing mammalian cells via lectin-mediated endocytosis. In addition, glyconanoparticles block adhesion of H. pylori to mammalian cells, suggesting that they can serve as inhibitors of infection of host cells by this pathogen. It has been also shown that owing to their magnetic properties, glyconanoparticles are useful tools to enrich lectin expressing cells. The combined results indicate that dual-modal glyconanoparticles are biocompatible and that they can be employed in lectin-associated biological studies and biomedical applications.

Gamma Knife radiosurgery for meningiomas arising from the tentorium: a 22-year experience.

In order to evaluate long term clinical and imaging outcomes, the authors retrospectively reviewed our 22-year experience using stereotactic radiosurgery (SRS) for tentorial meningiomas. Thirty-nine patients with tentorial meningiomas underwent SRS using various Gamma Knife technologies between 1988 and 2010. The most common presenting symptoms were headache, dizziness or disequilibrium, and ataxia. The median tumor volume was 4.6 cm(3) (range 0.5-36.6 cm(3)) and the median radiation dose to the tumor margin was 14 Gy (range 8.9-18 Gy). The median follow-up period was 41 months (range 6-183 months). At the last imaging follow-up, tumor volumes decreased in 22 patients (57 %), remained stable in 13 patients (33 %), and increased in 4 patients (10 %). The progression-free survival after SRS was 97 % at 1 year, and 92 % at 5 years. At the last clinical follow-up, 35 patients (90 %) showed no change in symptoms, 1 patient (2 %) showed improvement of their neurologic symptom, and 3 patients (8 %) demonstrated worsening symptoms. The rate of symptom worsening after SRS was 5 % at 1 year, and 10 % at 5 years. Asymptomatic peritumoral edema after SRS occurred in 2 patients (5 %). Symptomatic adverse radiation effect developed in 2 patients (5 %). SRS for tentorial meningiomas provided long-term effective tumor control and a low risk of radiation related complications.

Pituitary carcinoma with fourth ventricle metastasis: treatment by excision and Gamma-knife radiosurgery.

Pituitary carcinomas, which are rare, generally present with craniospinal and systemic metastases. Although several treatments exist, the prognoses of patients with pituitary carcinomas are extremely poor to date. In this report, the authors describe the case of a 23-year-old male who had undergone trans-sphenoidal surgery and radiotherapy for an invasive prolactinoma. Seven years later, he presented with a new 4th ventricle metastasis from the pituitary lesion, and it was diagnosed with a pituitary carcinoma. He underwent resection and Gamma-knife radiosurgery (GKRS). The tumor has been well controlled for over 3 years. To our knowledge, there have been no reports of the effects of GKRS in patients with pituitary carcinomas. GKRS might have considerable effects in the treatment of pituitary carcinomas.

Border Zone Maybe Correlated with Radiation Necrosis After Radiosurgery in Metastatic Brain Tumor.

BACKGROUND: Radiation necrosis (RN) after stereotactic radiosurgery (SRS) in brain metastases has been extensively evaluated, and RN is correlated with various risk factors. However, no study comprehensively analyzed the correlation between RN and the border zones of the brain that are vulnerable to ischemia. We hypothesized that patients with tumors in the border zone are at high risk of RN. Hence, the current study aimed to assess the correlation between border zone lesions and RN, with consideration of other predetermined factors. METHODS: This retrospective study included 117 patients with 290 lesions who underwent Gamma Knife SRS. Radiological and clinical analyses were performed to identify factors possibly correlated with RN. Notably, the lesion location was classified into 2 groups (border zone and nonborder zone) based on the blood supply. RESULTS: In total, 22 (18.8%) patients with 22 (7.5%) lesions developed RN. Univariate analysis revealed a significant correlation between RN and external border zone lesions, second course of SRS administered at the same site of the previous SRS, prescribed dose, and tumor volume. Multivariate analysis showed that border zone lesions, second course of SRS at the same site of the previous SRS, and tumor volume were significantly correlated with RN. CONCLUSIONS: Patients with tumors in the border zone are at high risk of RN. The potential risks of RN can be attributed hypothetically to hypoperfusion. Hence, the association between RN and border zone lesions seems reasonable.

Chronic subdural hematoma associated with the middle fossa arachnoid cyst: pathogenesis and review of its management.

BACKGROUND: The pathogenesis of chronic subdural hematoma (CSDH) associated with an arachnoid cyst (AC) is still not clear. We propose an origin of initial bleeding of CSDH in patients with AC based on our experience and discuss the management of this disease. MATERIALS AND METHODS: The total number of operations included in this study was 23. Eleven cases were indicated because of associated CSDH (group 1), and the other cases were due to different reasons (group 2). The relationship of the AC and dura was evaluated in patients who did not have CSDH (group 2) because patients with CSDH would have had structural changes of AC due to hematoma. RESULTS: In group 1, the age distribution was from 8 to 61 years (mean 23.0). The development of CSDH was not related with Galassi types. The hematomas were located outside of the outer cyst membrane in six patients and both inside and outside in three patients. In two patients, the location could not be reviewed. After suspicion of the outer cyst membrane as the origin of the bleeding site, we found small bridging vessels between the dura and outer cyst membrane in three of five consecutive patients in group 2. CONCLUSIONS: Based on our surgical experience of AC cyst, we found small bridging vessels between the dura and outer membrane of the AC. We suggested that these small vessels are the source of initial bleeding leading to CSDH in AC.

Full-range stress-strain curve estimation of aluminum alloys using machine learning-aided ultrasound.

Full-range stress-strain (SS) curves are crucial in understanding mechanical properties of a material such as the yield strength, ultimate tensile strength, and elongation. In this study, a full-range SS-curve was nondestructively estimated by applying machine learning to the ultrasonic amplitude-scan signal propagated through the material. The performance of the developed technique was validated using five-hundred aluminum alloy specimens with a wide spectrum of mechanical properties. The analyses of various ultrasonic properties, including nonlinearity and attenuation, with respect to the elements in the SS curves revealed how ultrasonics can be used to predict the SS curves without conventional destructive tensile testing. The proposed technique has significant potential for new applications in the fields of materials science and engineering, such as inline SS curve estimation during manufacturing.