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A transient model of frost growth on a flat plate was developed, taking the surface characteristics of the plate into consideration. Five regression models were applied, three traditional (Multiple Linear, LASSO, Ridge) and two machine-learning (Artificial Neural Network, Support Vector Machine) regression models. The training database was established using data extracted from previously published experimental studies. The experimental data consisted of forced convection (1067 data points) and natural convection data (992 data points). The model outputs were then evaluated using common statistical indicators and the best performing model was selected. The highest R2 values for the artificial neural network were 0.9899 and 0.9944 for forced and natural convection, respectively, after removal of outliers. The frost thickness was predicted for various conditions, including different surface characteristics. The model produced good predictions despite the occurrence of nonlinear complex growth mechanism dependent on various conditions in the dataset obtained.

Our objective was to analyze functional outcomes and prognostic factors in patients suffering from angiogram-negative non-perimesencephalic subarachnoid hemorrhage (non-PMH). In total, 1601 patients presenting with spontaneous SAH between January 2009 to December 2019 admitted to our institution were reviewed. Among them, 51 patients with angiogram negative non-perimesencephalic subarachnoid hemorrhage were analyzed. We divided patients into groups according to hemorrhage pattern and duration. Prognostic factors were assessed according to initial neurologic grade, early hydrocephalus, fisher grade, and duration of hemorrhage. Outcomes were assessed according to the modified Rankin Scale after 6 months. Overall, 41 patients (80.3%) with angiogram-negative non-PMH achieved a favorable outcome. In univariate analysis, good initial neurologic grade, absence of early hydrocephalus, non-Fisher-type 3 bleeding pattern, and short term hemorrhage (blood wash out7 days after onset) duration were significantly associated with a favorable outcome. In multivariate analysis, a non-Fisher-type 3 hemorrhagic pattern (p 0.05) and good initial neurologic state (p 0.01) were independent predictors of favorable outcomes in angiogram-negative non-PMH patients. Patients with angiogram-negative non-PMH generally had favorable outcomes. A non-Fisher-type 3 hemorrhagic pattern and good initial neurologic state were prognostic factors of a favorable outcome in non-PMH. Furthermore, patients with long-term SAH were more likely to develop hydrocephalus. Evaluating the pattern and duration of subarachnoid hemorrhage may allow better prediction of outcomes in patients with angiogram negative and non-PMH.

Objective The aim of this study was to analyze serum levels of vascular endothelial growth factor (VEGF) and endostatin in patients with cerebral treated by stereotactic radiosurgery (SRS), and to assess their association with radiological radiation-induced changes (RICs). Methods To measure serum biomarkers, peripheral venous blood was collected before SRS and 1 week, 1 month, 3 months, and 6 months after SRS. To evaluate RICs, clinical and neuroimaging follow-up were performed concurrently every 6 months after SRS. Results Twenty-seven patients were enrolled (11 in the group with RIC, 16 in the group without RIC). Serum VEGF and endostatin levels were positively correlated (P = 0.036, r = 0.405). In the group with RIC, the median serum VEGF 6 months after SRS (58.98 pg/mL) was significantly higher than that of the group without RIC (15.17 pg/mL) (P = 0.001). Multivariate analysis revealed that higher VEGF 6 months after SRS (P = 0.001, hazard ratio, 1.032; 95% confidence interval, 1.012–1.052) and lower endostatin 1 month after SRS (P = 0.007, hazard ratio, 0.964; 95% confidence interval, 0.935–0.993) were significantly associated with RICs. Conclusions Our results show that serum levels of VEGF 6 months after SRS were higher in the group with RIC. Serum levels of VEGF 6 months and endostatin 1 month after SRS were associated with the radiological RICs. Thus, serial measurements of serum VEGF and endostatin after SRS might help predict RICs in patients with arteriovenous malformation treated by SRS.

An hydroxythiophene-conjugated benzothiazole (T2(OH)B) was synthesized as a pH sensitive fluorescent probe. T2(OH)B displayed dual emission behavior due to the excited state intramolecular proton transfer (ESIPT) process, while the methoxy analogs, T2(OMe)B, did not. T2(OH)B showed strong fluorescence enhancement above physiological pHs. The applicability of T2(OH)B as a biological pH indicator was demonstrated by its use for staining mitochondrial compartment and H. pylori. Owing to its strong fluorescence emission with a large stokes shift and its effective response to pH, T2(OH)B serves as a platform for the design of new types of fluorescent probes.

Human pluripotent stem cell (hPSC)-derived myogenic progenitor cell (MPC) transplantation is a promising therapeutic approach for a variety of degenerative muscle disorders. Here, using an MPC-specific fluorescent reporter system (PAX7::GFP), we demonstrate that hPSC-derived MPCs can contribute to the regeneration of myofibers in mice following local injury and in mice deficient of dystrophin (mdx). We also demonstrate that a subset of PAX7::GFP MPCs engraft within the basal lamina of regenerated myofibers, adopt a quiescent state, and contribute to regeneration upon reinjury and in mdx mouse models. This subset of PAX7::GFP MPCs undergo a maturation process and remodel their molecular characteristics to resemble those of late-stage fetal MPCs/adult satellite cells following in vivo engraftment. These in-vivo-matured PAX7::GFP MPCs retain a cell-autonomous ability to regenerate and can repopulate in the niche of secondary recipient mice, providing a proof of principle for future hPSC-based cell therapy for muscle disorders.

In a numerical investigation of the thermal energy storage performance of a latent heat thermal energy storage system with three angled fins, the enthalpy-porosity model was used to simulate the phase-change process. To analyze the effect of the angle of inclination of the fin (θf) on the heat transfer characteristics and energy storage performance, a parametric study was performed in which θf was varied over the range −40∘≤θf≤40∘. The variation in energy storage performance according to fin angle is also analysed, in order to obtain an optimal fin angle for maximum energy storage performance for the geometric shape of interest. The results reveal that both the heat transfer characteristics and the energy storage performance are affected significantly by variations in θf. For cases where the fins are angled downwards, the upward flow is hampered, and where the fins are angled upwards, natural convection is intensified prior to the onset of thermal stratification. During the final stage of the charging process, the quantity of the remaining solid phase change material in the lower region increases, which delays the melting time. In order to evaluate the energy storage performance, the melting time, the total stored energy, and the mean power were calculated. For θf in the range −30∘≤θf≤−10∘, the energy storage performance can exceed that for the case of θf=0∘. The case of θf=−20∘ shows the best thermal energy storage performance as the average power is up to 19.3% higher than that for the case of θf=0∘ among all cases considered in present study.

A numerical investigation of a design modification of a two-dimensional supersonic gas ejector was undertaken via an adjoint method, with a focus on enhancing the performance of the ejector. Maximization of the secondary mass flow rate was used as an objective function. The entrance geometry and throat height of the primary nozzle were fixed, but the other geometries were allowed to vary during the design modification. The shape of the divergence of the primary nozzle, the nozzle exit position (NXP), and the entrance region of the mixing chamber were modified simultaneously using the adjoint method. The height of divergent section of primary nozzle (Hne), NXP, and the inlet height of the mixing chamber (Hmi) were enlarged by about 13.33%, 27%, and 49%, respectively, resulting in an entrainment ratio (ER) that was enhanced by about 37.17% compared to that obtained for the baseline geometry. Two simplified geometries from the adjoint modification were suggested, and have the same performance with the adjoint-modified geometry. Further investigation was performed by varying the height of the straight section of the mixing chamber of the simplified geometry. The results show that the ER increased by about 46.77% compared with that obtained using the simplified geometry.

In this study, an ultrasound generation and sensing system using a femtosecond laser is developed specifically for noncontact inspection of a moving object. In the developed femtosecond laser ultrasonic system, a laser pulse source is divided into pump and probe laser pulses. Using a pump laser pulse with a subpicosecond duration, ultrasounds with ultrashort wavelengths (micrometer to tens of nanometers) are generated up to THz. Then, the resulting ultrasounds are measured using a probe laser pulse based on reflectometry at a sampling frequency of up to 1.5 THz. The developed system is used to generate and measure ultrasounds from a silicon wafer while the wafer is moving in a horizontal direction. Because of the ultrashort pulse duration of the probe and pump laser pulses, the contact time of these pluses with respect to a moving object is extremely short (subpicosecond), and the distortion of ultrasounds due to object motion is minimized. Ultrasounds are measured from the silicon wafer in both pulse-echo and pitch-catch modes, and it is validated that the ultrasounds acquired from a moving condition of the silicon wafer are in good agreement with those obtained from a stationary condition. Then, the thickness of a submicrometer coating layer deposited on the silicon wafer was successfully estimated while the silicon wafer was moving up to 20 mm/s.

This paper numerically investigates the two-dimensional natural convection in a square enclosure with a vertical array of a hot elliptical cylinder and a hot circular cylinder with Rayleigh numbers in the range of 10 4 ⩽ Ra ⩽ 10 6 . An immersed boundary method was used to capture the wall boundary of the cylinders. The effects of the position and inclination angle ϕ of the elliptical cylinder were investigated. When the Rayleigh number increases to Ra = 106, the numerical solutions reach an unsteady state for all cases of the lower elliptical cylinder and the cases of the upper elliptical cylinder except at ϕ = 90 ° . The transition of the flow regime from unsteady state to steady state depends on the flow direction and the space between the upper cylinder and top wall of the enclosure due to the changes in the inclination angle of the elliptical cylinder. At Ra = 106 in the case of upper elliptical cylinder at ϕ = 0 ° , the time- and surface-averaged Nusselt numbers for the walls of the enclosure increase by about 1.99% compared to the case of two circular cylinders. The thermal performance and flow stability were influenced by the position and inclination angle of the elliptical cylinder.

Objective To analyze serum levels of S100 calcium-binding protein B (S100B), neuron-specific enolase (NSE), and interleukin (IL)-6 in pediatric patients with traumatic brain injury (TBI) and to assess their relationship with clinical outcome. Methods To measure biomarkers, peripheral venous blood was collected within 6 hours and 1 week after TBI. Initial Glasgow Coma Scale (GCS) scores and Glasgow Outcome Scale scores 6 months after the trauma were used to evaluate clinical outcome. Results Median serum levels of S100B (178.12 pg/mL), NSE (16.54 ng/mL), and IL-6 (15.48 pg/mL) at admission decreased significantly 1 week after TBI to 40.86 pg/mL, 5.85 ng/mL, and 8.63 pg/mL. In the group with poor GCS scores, serum S100B and NSE levels both at admission and 1 week after TBI were significantly higher than levels in the group with good GCS scores. Serum S100B and NSE levels 1 week after injury in patients with unfavorable 6-month outcomes were significantly higher than levels 1 week after injury in patients with favorable outcomes. Conclusions Serum levels of S100B, NSE, and IL-6 decreased 1 week after injury. Serum levels of S100B and NSE at admission were related to initial GCS scores, and these levels 1 week after TBI were related to 6-month Glasgow Outcome Scale scores. Thus, serial measurements of serum S100B and NSE, but not IL-6, may help assess brain damage and clinical outcome of pediatric patients with TBI.

This paper discusses the effect of the hole location in the fan case on the thermal performance of a gas oven range. A computational fluid dynamics (CFD) study was carried out in ANSYS FLUENT. A DO model was used to include the effect of thermal radiation in the oven cavity. A test geometry was developed by referencing a real product, including the oven cavity, external walls, fan cases, fans, and burners. The simulation was validated with experimental data and showed that the maximum difference in temperature is 2.5%, while the difference in average temperature is 0.44%. A total of 15 cases were examined using different hole locations in the fan case. The direction of the velocity vector at the holes was changed by the different hole locations, and the flow pattern and temperature distribution inside the oven cavity also changed dramatically as a result. The thermal performance was evaluated based on the average temperature and temperature uniformity inside the oven cavity.

Experimental and numerical investigations were carried out for a system including the thermoelectric modules with heat sinks inside a square duct. A thermoelectric module model was developed using the commercial computational fluid dynamics code FLUENT and user-defined functions (UDF). The performance of a thermoelectric module was analyzed by a visualization technique of temperature variation over time. In this study, UDFs are employed to specify the heat flux terms of the cooling capacity and the heat generation of thermoelectric modules. As a result, the data obtained with the numerical method was generally in good agreement with those obtained by the experiments over time at each inlet temperature. Detailed effects of the various parameters of heat sinks attached the thermoelectric module were discussed, and consequently these parameters had a great influence upon the performance of the thermoelectric module.

Additive manufacturing (AM), commonly known as 3D printing, is an emerging technology for manufacturing metal parts. Recently, micro-oxide inclusions, which are inevitably generated during AM processes owing to the high-temperature environment, have been noted to enhance the mechanical strength of AM metal parts. However, an explicit nondestructive testing (NDT) method to assess the micro-oxide inclusions of AM metal parts has not been reported yet owing to the difficulty of sensing micro-inclusions. In this study, the micro-oxide inclusions of AM metal parts were evaluated nondestructively using a nonlinear ultrasonic technique. The uniqueness and advantages of this study are (1) the development of a micro-oxide inclusion evaluation technique for AM metal parts, (2) superior evaluation ability for micro-inclusions compared to conventional NDT; (3) applicability of the proposed method in assessing the strengthening of the mechanical properties of the AM parts by the inclusions; and (4) potential for nondestructive online monitoring. The performance of the proposed method was validated using specimens fabricated under various 3D printing conditions. The results of the micro-oxide inclusions assessed by the proposed method were consistent with the metallography and tensile testing results. Furthermore, the performance of the proposed method was better than that of conventional NDT.

This study numerically investigated the melting phenomena of a phase change material (PCM) in a latent heat thermal storage system with a finned elliptical inner cylinder. The enthalpy–porosity model was used to simulate the phase change process of the PCM. A parametric study was performed by varying the length of the fin in the range of 5, 6.5, and 8 mm and at temperatures of 56.15, 69.16, and 92.22°C, considering three different geometric types. The distributions of the liquid fraction, temperature, and velocity vector were numerically investigated to analyze the effects of these variables on the melting performance of the latent thermal energy storage system. The results indicate that the heat and mass transfer characteristics can be significantly affected by changes in the geometric types, length of the fin, and temperature of the inner cylinder. Based on the results from the numerical simulations, the multilayer perceptron neural network model was trained to estimate the melting time of the PCM with respect to the changes in the main variables considered. It was found that a multi-layer perceptron neural network model can estimate the melting time more accurately than the least square regression method.

Directed energy deposition (DED), also known as laser cladding, is one type of additive manufacturing where a high-power laser combined with a coaxial powder delivery system is used to produce metal components layer-by-layer. Despite many advancements in DED, little work has been accomplished in online estimation of mechanical properties, such as Young's modulus and Poisson's ratio, during the DED process. In this study, an online mechanical properties estimation technique was developed for the DED process using femtosecond laser ultrasonics and laser polishing. The unique contributions of this study are the following: (1) the development of a fully noncontact and nondestructive technique for the estimation of Young's modulus and Poisson's ratio using a femtosecond laser, (2) layer-by-layer estimation of mechanical properties accomplished by achieving micrometer-level spatial resolution, (3) laser ultrasonic measurement from a deposited metal layer using laser polishing instead of mechanical polishing, and (4) potential for online operation during the DED process. The performance of the proposed technique was examined using specimens fabricated under various DED operation conditions. The Young's modulus and Poisson's ratio values estimated by the proposed technique were consistent with those obtained from independent tensile tests performed after the completion of the DED process.

Objective We reviewed our 7-year experience to assess the efficacy of stereotactic radiosurgery (SRS) for dural carotid cavernous fistulas (DCCFs). We analyzed the clinical outcome, complications and angiographic results. Methods We performed a retrospective analysis of 18 consecutive patients with DCCF treated by SRS alone using Gamma Knife between 2009 and 2015. Median target volume was 2.6 cm 3 (range, 0.6–11.6 cm 3 ) and median radiation dose to the target was 17 Gy (range, 14–19 Gy). Median follow-up period was 30 months (range, 6-65 months). Results Fifteen patients (83%) achieved a total obliteration of the DCCF and a subtotal obliteration of the DCCF was achieved in three patients (17%). Total obliteration rates after SRS were 53% at 1 year and 90% at 2 years. Twelve patients (67%) showed complete recovery from symptoms or signs and six patients (33%) showed incomplete recovery. Improvement rates of neurological function after SRS were 56% at 1 month, 72% at 3 months, and 94% at 6 months. None of the patients experienced radiation-related complications. A univariate analysis revealed that absence of hypertension (p = 0.025), seizure (p = 0.025), and cortical venous drainage (p = 0.013) were significantly associated with symptoms improvement. Conclusion SRS for DCCFs offered a high obliteration rate with low risk of radiation-induced complications. In patients with benign DCCFs that are not amenable to embolization or microsurgery, SRS is a safe and effective treatment for complete obliteration of the arteriovenous shunt and for improving the quality of life.

In this study, a low-velocity impact test of glass fiber-reinforced polypropylene (GFPP) composites was simulated considering interlaminar fracture toughness. In the simulation, intralaminar and interlaminar damage were modeled using the continuum damage mechanics (CDM) and cohesive zone method (CZM) models, respectively. The B-K criterion was used for the interlaminar damage model along with experimental results, which were obtained from fracture toughness tests of modes I and II and the mixed mode. Low-velocity impact tests were performed to verify the developed damage model, and various characteristics such as delamination and the force–displacement were evaluated. Finally, it was found that the developed damage model with interlaminar fracture toughness can be used to accurately predict the impact behavior of GF/PP composites, including interlaminar delamination.

This study numerically investigates the effect of the number and arrangement of tubes on the melting performance of a phase change material (PCM) in a multi-tube shell-and-tube latent heat thermal energy storage (LHTES) system. An enthalpy-porosity model was used to simulate the phase change process. Eight arrangements of tubes were examined. The melting characteristics, energy density, distributions of the liquid fraction and temperature, heat transfer rate, and melting time were analyzed. The melting performance and energy density were influenced by both the number and arrangement of tubes. An increase in the number of tubes enhanced the melting rate in the initial stage and the energy density. The tube arrangement affected the required melting time. Two vertically arranged tubes resulted in the lowest melting time, and eight tubes resulted in the highest energy density. A correlation is proposed to estimate the total melting time with respect to the number and arrangement of tubes in LHTES.

Objective The purpose of this study was to evaluate the efficacy and safety of gamma knife radiosurgery (GKRS) for the treatment of symptomatic brainstem intra-axial cavernous malformations (CMs) associated with high surgical morbidity. Methods Twenty-one patients with symptomatic brainstem intra-axial CMs were treated by GKRS between 2005 and 2010. One patient was lost to follow-up. The median age of the patients was 39.5 years (range, 24−69 years). All patients had experienced 1 or more symptomatic hemorrhages before GKRS (range, 1−3). The median marginal radiation dose was 13 Gy, and the median volume of the malformation was 0.56 mL. The median follow-up period after radiosurgery was 32 months (range, 12−82 months; mean, 38.9 months). Results Before GKRS, 31 hemorrhages (1.55 per patient) were observed. The annual hemorrhage rate before GKRS was 39.5%, excluding the first hemorrhage. After GKRS, 1 hemorrhage (0.05 per patient) was identified. It occurred 6 months after radiosurgery. The patient showed complete recovery to a premorbid status with steroid medication. The annual hemorrhage rate after GKRS was 8.2% for the first 2 years. After the expected latency period, no hemorrhages were identified. One patient (5%) exhibited permanent paresthesia, which was a new neurologic symptom in absence of any hemorrhagic event, after the radiosurgery. Conclusions GKRS seems to be relatively effective and safe for reducing the rebleeding rate of brainstem intra-axial CMs that have high surgical risk. Careful selection of a low marginal dose and an optimal radiosurgical technique are helpful to achieve good outcomes.

We investigated the relationship between fibrinolytic factors and computed tomography (CT) findings in patients with chronic subdural hematomas (CSDHs).Thirty-one patients with CSDHs were divided on the basis of CT findings into heterogeneous and homogeneous groups. A sample from the subdural hematoma was obtained at surgery to measure the concentrations of fibrinogen and D-dimer.The mean level of fibrinogen in the heterogeneous group, including the layering (n=4) and mixed (n=10) type, was 88.2±121.2 mg/dL, whereas in the homogeneous group, including high density (n=2), isodensity (n=9), and low density (n=6) types, it was25 mg/dL. The concentration of fibrinogen was significantly higher in the heterogeneous group than in the homogeneous group (p=0.006). The mean level of D-dimer in the heterogeneous group was 35,407.9±16,325.5 μg/L, whereas for the homogeneous group it was 1476.4±2091.4 μg/L. The concentration of D-dimer was significantly higher in the heterogeneous group than in the homogeneous group (p0.001).The layering and mixed types of CSDH exhibited higher concentrations of fibrinogen and D-dimer in subdural hematoma than the homogeneous types. These fibrinolytic factors appear to be associated with evolution in CSDHs with heterogeneous density.

The aim of this study was to compare the effectiveness of gamma knife radiosurgery (GKS) for the treatment of multiple brain metastases from lung cancer with that of whole brain radiation therapy (WBRT). Patients with multiple (2-20) brain metastases were divided into two groups for initial brain tumor management: a GKS group (14 patients) and a WBRT group (19 patients). The patients were stratified by gender, age, initial Karnofsky performance status score, control of the primary site, known extracranial metastases, number of brain metastases, diameter of the maximal lesion, chemotherapy, and recursive partitioning analysis (RPA) Class. The 6-month and 1-year overall survival rates were 64.3% and 47.7%, respectively, in the GKS group, and 42.1% and 10.5%, respectively, in the WBRT group. The median survival time was 32 weeks in the GKS group and 24 weeks in the WBRT group. The overall survival time in the GKS group was significantly longer than in the WBRT group (p = 0.04). The univariate analysis suggests that survival was increased in both patients with a controlled primary tumor site and in the GKS group (p = 0.03, 0.04). The use of GKS in patients with multiple brain metastases significantly improved patient survival compared to the employment of WBRT. When we assessed the subgroups, systemic disease control and GKS were significant variables by univariate analysis.

Background Surgical exposure of the upper cervical spine is challenging, and optima approaches are subjects of debate. The high anterior cervical approach to the upper cervical spine is a favorable method that provides direct and wide exposure for fusion and anterior decompression of the upper cervical spine. The authors present their experiences with 15 patients in whom fusion and instrumentation on the upper cervical spine were performed via the prevascular extraoral retropharyngeal approach. Methods A series of 15 patients who were surgically treated using the high anterior cervical retropharyngeal approach was reviewed. These cases involved a C2 hangman's fracture with significant angulation and translation (11 patients), C2 EDH (1 patient), C2 chordoma (1 patient), C3-4 metastasis (1 patient), and C2-3-4 OPLL (1 patient). Results Twelve patients underwent C2-3 fusion followed by instrumentation. C2-5 fusion with instrumentation was performed in 2 patients. One patient experienced occipitocervical fusion after anterior removal of a C2 chordoma. A solid fusion was achieved in 13 patients. However, 1 patient needed additional posterior fusion because of fusion failure, and the other died due to ischemic heart disease. There was 1 patient who developed permanent dysphagia related to the hypoglossal nerve and 2 who had transient dysphagia. No complications occurred related to the marginal branch of the facial nerve or submandibular gland. Conclusions The high anterior cervical approach is a useful surgical technique for an upper cervical lesion without severe morbidity, which allows direct anterior access to C2 and C3 while allowing extension to the lower cervical spine.

Hearing loss in patients who have undergone shunt placement for a hydrocephalus is perhaps an underestimated complication rather than a rare event. There appears to be a correlation between the occurrence of hearing loss and patient characteristics consistent with excessive drainage of cerebrospinal fluid (CSF) and patent cochlear aqueduct (CA). We present the case of a 77-year-old man with unilateral dominant sensorineural hearing loss after a shunt placement for normal pressure hydrocephalus (NPH) combined with a patent cochlear aqueduct. Based on our experience and a review of the literature, we suggest an early restoration of the reduced CSF pressure using a programmable valve as a treatment strategy, which might prevent the persistent hearing loss.