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Liquid-filled containers (LFC) are widely used to store and transport petroleum, chemical reagents, and other resources. As an important target of military strikes and terrorist bombings, LFC are vulnerable to blast waves and fragments. To explore the protective effect of polyurea elastomer on LFC, the damage characteristics of polyurea coated liquid-filled container (PLFC) under the combined loading of blast shock wave and fragments were studied experimentally. The microstructure of the polyurea layer was observed by scanning electron microscopy, and the fracture and self-healing phenomena were analyzed. The simulation approach was used to explain the combined blast- and fragments-induced on the PLFC in detail. Finally, the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively compared. Results showed that the polyurea reduces the perforation rate of the fragment to the LFC, and the self-healing phenomenon could also reduce the liquid loss rate inside the container. The polyurea reduces the degree of depression in the center of the LFC, resulting in a decrease in the distance between adjacent fragments penetrating the LFC, and an increase in the probability of transfixion and fracture between holes. Under the close-in blast, the detonation shock wave reached the LFC before the fragment. Polyurea does not all have an enhanced effect on the protection of LFC. The presence of internal water enhances the anti-blast performance of the container, and the hydrodynamic ram (HRAM) formed by the fragment impacting the water aggravated the plastic deformation of the container. The combined action has an enhancement effect on the deformation of the LFC. The depth of the container depression was 27% higher than that of the blast shock wave alone; thus, it cannot be simply summarized as linear superposition.

A density clustering-based health monitoring model for complex equipment is proposed for the complex equipment historical data which often has the characteristics of non-spherical shape. The local density and inter-class distance of each sample are estimated from the historical data, and the statistical properties of both are considered to determine the clustering center of the data. For the newly collected complex equipment health status monitoring data, if it is reachable with the density of the clustering center, the complex equipment is considered to be in a healthy state, otherwise it is in a non-healthy state. An actual complex equipment data set is analyzed by numerical simulation techniques, as well as visualization techniques such as scatter plots, box plots and parallel coordinate systems are used to verify the reliability of the calculated results, and the simulation results show that the proposed method can effectively monitor the health status of complex equipment.

The optimization of the contradiction between the toughness and strength of nacre has become a focus of attention for material researchers. In the present work, objective functions for several parameters, such as tablet shape (flat and wavy), dimensions (length, thickness, dovetail angle), mechanical properties (modulus of elasticity, shear modulus), overlap length of layers, and matrix thickness, were established from the three basic mechanical properties of the bionic mother-of-pearl structure (stiffness, strength, and toughness). Subsequently, the objective function was iteratively optimized using the non-dominated sorting genetic algorithm II (NSGA II) based on the constraint function. Finally, a numerical simulation model was developed using the key parameters derived from the structural optimization to investigate the penetration performance of a 12.7 mm projectile on different structures. Comparing the damage failure scenario, penetration resistance, ballistic performance, and energy absorption efficiency of different structures, it was found that after parameter optimization, wave-staggered composite plate reduced the penetration depth by 31.61 %, improved the ballistic limit by 27.21 %, and enhanced the energy absorption efficiency of ceramic by 8.30 % compared to the block plate.

Clay brick masonry unit (CBMU) walls are widely used in building structures, and its damage and protection under explosion loads have been a matter of concern in the field of engineering protection. In this paper, a series of full-scale experiments of the response characteristics of 24 cm CMBU walls unreinforced and reinforced with polyurea elastomer subjected to blast loading were carried out. Through setting 5.0 kg TNT charges at different stand-off distances, the damage characteristics of masonry walls at different scaled distances were obtained. The reinforcement effect of different polyurea coating thicknesses and methods on the blast resistance performance of masonry walls under single and repeated loads were also explored. Five failure grades were summarized according to the dynamic response features of masonry walls. Based on the stress wave propagation pattern in multi-media composite structures, the internal stress distribution of masonry walls were analyzed, and the division basis of the masonry walls’ failure grades was then quantified. Combined with Scanning Electron Microscope(SEM) images, the deformation characteristics of soft and hard segments of polyurea and effects of detonation products on microstructures were revealed respectively, which provides an important reference for the design and application of polyurea in the blast resistance of clay brick masonry walls.

Natural marine biological structures have evolved over a long period of time, and their comprehensive performance has huge advantages over artificial materials. In order to improve the overall strength of the artificial structure, inspired by the layered structure of nacre, a nacre-like steel-polyurea composite plate was designed as a new impact-resistant structure. On this basis, the damage deformation of three different layered steel-polyurea composite plates with nacre-like structure under different projectile velocities was simulated. The damage failure morphology of nacre-like composite plates with different layered numbers was analyzed, and consequently, five failure toughening mechanisms of nacre-like composite plates were summarized. Then, the fitted ballistic performance curves were used to compare the ballistic performance of nacre-like composite plates with different delamination, and it was found that the composite plates could reduce the residual ballistic velocity by 24.58% and increase the ballistic limit by 27.86%, and the energy dissipation mechanism of the composite plates was explained by the energy release of steel and polyurea layers. Finally, the theoretical analysis reveals that the increase in the delamination number can effectively increase the equivalent modulus of the nacre-like composite plate, thus enhancing the penetration resistance of the composite plate.

In this study, the anti-penetration performance of polyurea/ASTM1405-steel composite plate subjected to high velocity projectile was analyzed. Two kinds of modified polyurea material (AMMT-053 and AMMT-055) were selected and a ballistic impact testing system including speed measuring target system and high-speed camera was designed. This experiment was conducted with a rifle and 5.8 mm projectile to explore the effects by the polyurea coating thickness, the polyurea coating position and the glass-fiber cloth on the anti-penetration performance of polyurea/ASTM1405-steel composite plate. The result showed that the effects of polyurea coating position were different between two types of polyurea, and that the effects of glass-fiber position were disparate between two types of polyurea as well. For AMMT-053 polyurea material, it was better to be on front face than on rear face; whereas for AMMT-055 polyurea, it was better to be on rear surface although the difference was very subtle. Additionally, formulas had been given to describe the relationship between the effectiveness of polyurea and the thickness of polyurea coating. In general, AMMT-055 had better anti-penetration performance than AMMT-053. Furthermore, five typical damage modes including self-healing, crack, local bulge, spallation and local fragmentation were defined and the failure mechanism was analyzed with the results of SHPB test. Additionally, the bonding strength played an important role in the anti-penetration performance of polyurea/steel composite plate.

Objective: Community stroke education is a regulated, integral component of stroke systems of care. However, little is known about the types of activities conducted by hospitals. This study was designed to examine the annual requirement for community stroke education among New York State's 119 designated Primary Stroke Centres and identify areas for improvement that may have an implication on stroke outcomes. Design: Cross-sectional survey design Setting: All 119 New York State designated Primary Stroke Centres were invited to participate. Methods: Participating hospitals completed a 29-item online questionnaire assessing multiple domains related to community stroke education including hospital characteristics, allocated resources, implementation barriers, current community stroke education practices and willingness to adopt best practice guidelines. Data were analysed using univariate descriptive and chi-square statistics. Results: Eighty-eight percent of hospitals completed the survey (105/119). Respondents were mostly stroke coordinators and stroke directors. Stroke outreach education was conducted two to four times per year in 58% of the hospitals (n = 69). Community stroke education included behavioural risk factor modification, the detection of stroke risk through screening and stroke preparedness education at health fairs. Although 95% of hospitals (n = 98) reported using at least one best practice approach for these activities, evaluation was generally poor, with only about 23% (n = 24) implementing outcome-specific assessments. Major barriers to stroke outreach were inadequate staffing, time constraints and lack of funding. Conclusion: Hospital-driven community stroke education efforts occur infrequently and are poorly evaluated. This component of stroke systems of care would benefit from guidelines from regulatory agencies, which currently do not exist.

Coronavirus disease 2019 (COVID-19) is an acute respiratory infectious disease caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The US FDA has approved several therapeutics and vaccines worldwide through the emergency use authorization in response to the rapid spread of COVID-19. Nevertheless, the efficacies of these treatments are being challenged by viral escape mutations. There is an urgent need to develop effective treatments protecting against SARS-CoV-2 infection and to establish a stable effect-screening model to test potential drugs. Polyclonal antibodies (pAbs) have an intrinsic advantage in such developments because they can target rapidly mutating viral strains as a result of the complexity of their binding epitopes. In this study, we generated anti–receptor-binding domain (anti-RBD) pAbs from rabbit serum and tested their safety and efficacy in response to SARS-CoV-2 infection both in vivo and ex vivo. Primary human bronchial epithelial two-dimensional (2-D) organoids were cultured and differentiated to a mature morphology and subsequently employed for SARS-CoV-2 infection and drug screening. The pAbs protected the airway organoids from viral infection and tissue damage. Potential side effects were tested in mouse models for both inhalation and vein injection. The pAbs displayed effective viral neutralization effects without significant side effects. Thus, the use of animal immune serum–derived pAbs might be a potential therapy for protection against SARS-CoV-2 infection, with the strategy developed to produce these pAbs providing new insight into the treatment of respiratory tract infections, especially for infections with viruses undergoing rapid mutation.

Integral imaging is a type of true three‐dimensional (3D) display technology that uses a lens array to reconstruct vivid 3D images with full parallax and true color. In order to present a high‐quality 3D image, it's vital to correct the axial position error caused by the misalignment and deformation of the lens array which makes the reconstructed lights deviate from the correct directions, resulting in severe voxel drifting and image blurring. We proposed a sub‐pixel marking method to measure the axial position error of the lenses with great accuracy by addressing the sub‐pixels under each lens and forming a homologous sub‐pixel pair. The proposed measurement method relies on the geometric center alignment of image points, which makes the measurement accuracy high. Additionally, a depth‐based sub‐pixel correction method was proposed to eliminate the voxel drifting. The proposed correction method takes the voxel depth into consideration. The experimental results well confirmed that the proposed measuring and correction methods can greatly suppress the voxel drifting caused by the axial position error of the lenses, and greatly improve the 3D image quality. [ABSTRACT FROM AUTHOR]

In this study, the authors introduced energy entropy as a reference feature into the field of blast vibration recognition classification and achieved good results. On the basis of the previous experimental database, 4 kinds of typical vibration signals were selected to form the sample group (building collapse vibration, surface rock blast vibration, underground tunnel blast vibration, and natural gas pipeline explosion vibration). EEMD (ensemble empirical mode decomposition) algorithm was used to calculate the energy entropy of each signal. Taking eigenvector composed of CEE (components of energy entropy) as input, multiclassification SVM algorithm was used for training and prediction. Prediction accuracy was more than 80%. Compared with BP (backpropagation) neural network algorithm, SVM (support vector machine) algorithm has higher training efficiency. The research results can be used in urban vibration monitoring, identify the nature of vibration source in time, and provide technical support for rapid response of emergency rescue.

In this paper, the penetration resistance of 6061 aluminum plates to explosively formed projectiles (EFPs) at the incidence angles of 0°, 15°, 30°, and 45° was studied. The penetration process was roughly divided into three typical stages--the plastic flanging stage of the target, the righting stage of the projectile, and the plug formation stage of the target. Through the energy analysis, the energy consumption of the aluminum plate increased with the increase in the incidence angle during the entire penetration process. Through the microscopic analysis of the perforated wall surface of the aluminum plate, it was found that there were distinct boundaries and differences between the plastic reaming zone and the punching plug fracture zone.. Overall, four kinds of classification modes were proposed for the damage of the aftereffect plate, which provides a method to evaluate the aftereffect of EFP oblique penetration into 6061 aluminum plates. [ABSTRACT FROM AUTHOR]

The experimental investigations on the square tubes with various stand-off distances and wall thickness were helpful to understand the dynamic response of metal shell under single and double explosion. Therefore, the effect of stand-off distance, wall thickness, and amounts of explosion on the deformation and damage of the square tubes and the regular pattern of the fracture development was analyzed by dimensions of local plastic deformation, volume of the depression area, and crack type. The result reveals that the deformation and fracture mode of steel square tubes gradually transform from local deformation to rupture with the decrease of wall thickness and stand-off distance. Besides, the failure degrees of square tubes under a double explosion were relatively higher than those of square tubes under a single explosion. In addition, the experiment indicates that the side corners of the square tube are very vulnerable, and they are damaged easily by the stress concentration and shear effect. The conclusion provides an important scientific basis for the structural design of square-tube structures and calculation of engineering protection.

Objective: Patients with developmental disabilities (DD) are frequently excluded from acute ischemic stroke (AIS) randomized control trials. We sought to evaluate the impact of having DD on this patient cohort Methods: The National Inpatient Sample was analyzed to explore the impact of AIS and treatment on discharge dispositions in patients with DD. Clinical characteristics, treatments, and outcomes were compared to fully-abled patients with AIS. Results: 1,605,723 patients with AIS were identified from 2010–2019, of whom 4094 (0.30%) had a DD. AIS patients with DD were younger (60.31 vs 70.93 years, p < 0.01), less likely to be Caucasian (66.37%vs 68.09%, p = 0.01), and had higher AIS severity (0.63 vs 0.58, p < 0.01). Tissue plasminogen activator (tPA) was administered in 99,739 (6.2%) fully-abled patients and 196 (4.79%) of patients with DD (p < 0.01). Endovascular thrombectomy (EVT) was performed in 21,066 (1.31%) of fully-abled patients and 35 (0.85%) of patients with DD (p < 0.01). The presence of developmental disabilities were predictive of lower rates of tPA (OR:0.71,CI:0.56–0.87,p < 0.01) and EVT (OR:0.24,CI:0.16–0.36,p < 0.01). In a propensity score-matched cohort of all AIS patients who underwent EVT, there was no difference in functional outcome (p = 0.41), in-hospital mortality (0.10), and LOS (p = 0.79). Conclusion: AIS patients with DD were less likely to receive tPA and EVT compared to fully-abled patients. Individuals with DD had higher mortality and worse discharge disposition. There was no significant difference in post-EVT outcomes between fully-abled patients and patients with developmental disabilities. In the absence of prospective clinical trials, population based cross-sectional analyses such as the present study provide valuable clinical insight. [ABSTRACT FROM AUTHOR]

Background and Aims: Although intravenous thrombolysis (IVT) represents standard-of-care treatment for acute ischemic stroke (AIS) in eligible adult patients, definitive evidence-based guidelines and randomized clinical trial data evaluating its safety and efficacy in the pediatric population remain absent from the literature. We aimed to evaluate the utilization and outcomes of IVT for the treatment of pediatric AIS using a large national registry. Methods: Weighted hospitalizations for pediatric (<18 years of age) AIS patients were identified in the National Inpatient Sample during the period of 2001 to 2019. Complex sample statistical methods were performed to assess unadjusted and adjusted outcomes in patients treated with IVT or other medical management. Results: Among 13,901 pediatric AIS patients, 270 (1.9%) were treated with IVT monotherapy (median age 12.8 years). IVT-treated patients developed any intracranial hemorrhage (ICH) at a rate of 5.6% (n = 15), and 71.9% (n = 194) experienced favorable functional outcomes at discharge (to home or to acute rehabilitation). Following propensity-score adjustment for age, acute stroke severity, infarct location, and etiological/comorbid conditions, IVT was not associated with an increased risk of any ICH (5.6% vs 5.4%, p = 0.931; adjusted odds ratio (aOR) = 1.01, 95% confidence interval (CI) = 0.48–2.14, p = 0.971), nor with favorable functional outcome (71.9% vs 74.5%, p = 0.489; aOR = 0.88, 95% CI = 0.60–1.29, p = 0.511) in comparison with other medical therapy. Conclusions: Twenty years of population-level data in the United States demonstrate that pediatric AIS patients treated with IVT experienced high rates of favorable outcomes without an increased risk of hemorrhagic transformation. [ABSTRACT FROM AUTHOR]