Direct Imaging of Tunable Crystal Surface Structures of MOF MIL-101 Using High-Resolution Electron Microscopy.

Metal-organic frameworks (MOFs) are often synthesized using various additives to modulate the crystallization. Here, we report the direct imaging of the crystal surface of MOF MIL-101 synthesized with different additives, using low-dose high-resolution transmission electron microscopy (HRTEM), and identify three distinct surface structures, at subunit cell resolution. We find that the mesoporous cages at the outermost surface of MIL-101 can be opened up by vacuum heating treatment at different temperatures, depending on the MIL-101 samples. We monitor the structural evolution of MIL-101 upon vacuum heating, using in situ X-ray diffraction, and find the results to be in good agreement with HRTEM observations, which leads us to speculate that additives have an influence not only on the surface structure but also on the stability of framework. In addition, we observe solid-solid phase transformation from MIL-101 to MIL-53 taking place in the sample synthesized with hydrofluoric acid.

The Impact of Ambient Air Pollution on Allergic Rhinitis Symptoms: A Prospective Follow-Up Study.

Air pollution has become a serious public health problem and there is evidence that air pollution affects the incidence of allergic rhinitis. To further investigate the effect of ambient air pollutants on the severity of allergic rhinitis symptoms, a prospective follow-up study in patients with allergic rhinitis was conducted. A total of 167 allergic rhinitis patients with a mean age of 35.4 years, who were visiting the hospital, were enrolled. The daily symptom severity of allergic rhinitis and the concentrations of six air pollutants, including PM2.5, PM10, SO2, CO, O3 and NO2, were collected through follow-up investigations. The impact of ambient air pollutants on symptom severity was assessed via multi-pollutant models. Among several typical ambient air pollutants, we observed correlations of allergic rhinitis symptoms with PM2.5, PM10, CO, SO2 and NO2, whereas O3 showed no such correlation. Specifically, PM2.5 and PM10 were significantly associated with sneezing and nasal blockage. NO2 was significantly correlated with symptoms of rhinorrhea, itchy nose and itchy eyes. CO was significantly linked to sneezing and nasal blockage symptoms. These air pollutants not only had a direct impact on allergic rhinitis symptoms but also exhibited a lagging effect. This study indicates that short-term exposure to air pollutants is associated with exacerbation of nasal symptoms in patients with allergic rhinitis, leading to a decline in their quality of life.

Development and testing of a deep learning algorithm to detect lung consolidation among children with pneumonia using hand-held ultrasound.

BACKGROUND AND OBJECTIVES: Severe pneumonia is the leading cause of death among young children worldwide, disproportionately impacting children who lack access to advanced diagnostic imaging. Here our objectives were to develop and test the accuracy of an artificial intelligence algorithm for detecting features of pulmonary consolidation on point-of-care lung ultrasounds among hospitalized children. METHODS: This was a prospective, multicenter center study conducted at academic Emergency Department and Pediatric inpatient or intensive care units between 2018-2020. Pediatric participants from 18 months to 17 years old with suspicion of lower respiratory tract infection were enrolled. Bedside lung ultrasounds were performed using a Philips handheld Lumify C5-2 transducer and standardized protocol to collect video loops from twelve lung zones, and lung features at both the video and frame levels annotated. Data from both affected and unaffected lung fields were split at the participant level into training, tuning, and holdout sets used to train, tune hyperparameters, and test an algorithm for detection of consolidation features. Data collected from adults with lower respiratory tract disease were added to enrich the training set. Algorithm performance at the video level to detect consolidation on lung ultrasound was determined using reference standard diagnosis of positive or negative pneumonia derived from clinical data. RESULTS: Data from 107 pediatric participants yielded 117 unique exams and contributed 604 positive and 589 negative videos for consolidation that were utilized for the algorithm development process. Overall accuracy for the model for identification and localization of consolidation was 88.5%, with sensitivity 88%, specificity 89%, positive predictive value 89%, and negative predictive value 87%. CONCLUSIONS: Our algorithm demonstrated high accuracy for identification of consolidation features on pediatric chest ultrasound in children with pneumonia. Automated diagnostic support on an ultraportable point-of-care device has important implications for global health, particularly in austere settings.

Visual Multimedia Intelligent Computing System for Seismic Performance of Bridge Structure Based on Object-Oriented Technology.

In order to further promote the standardization of seismic performance design of bridge structures, one must ensure the quality of bridge design and improve design efficiency. First, based on the basic principle of the probabilistic pushover method, the randomness of the structural pushover curve is attributed to the randomness of plastic hinges. Second, the visualization of seismic performance of bridge structures based on the object-oriented technology is adopted. So that the randomness of seismic action can be considered in the analysis of seismic performance. Finally, the limit state equation of the seismic performance of the structure is used to evaluate the reliability of the seismic performance of the bridge in each limit state conveniently. The results show that the failure probability of the structure in each limit state is less than 0.5 under different basic accelerations from 0 to 0.4 g. The software method is simple in calculation and has a strong adaptability, avoiding the difficulty of seismic reliability analysis caused by large-scale simulation and large amount of calculation of traditional structures. Therefore, this method can be easily applied to the probabilistic analysis of seismic behavior of bridge structures under large earthquakes without evaporative deformation failure criterion.

Ultrathin and Highly Crumpled/Porous CoP Nanosheet Arrays Anchored on Graphene Boosts the Capacitance and Their Synergistic Effect toward High-Performance Battery-Type Hybrid Supercapacitors.

Constructing novel electrode materials with supernal specific capacitance and cycle stability is important for the practical applications of supercapacitors. Herein, ultrathin and highly crumpled CoP/reduced graphene oxide (rGO) nanosheet arrays are grown on nickel foam (NF) through a hydrothermal-phosphidation route. Benefitting from the synergistic effects of CoP with large specific capacity and rGO with high conductivity and ultrathin nanosheet arrays structure, CoP/rGO shows extraordinary electrochemical performance. The CoP/rGO electrode possesses a superior specific capacity of 1438.0 C g-1 (3595.0 F g-1) at 1 A g-1, which is 3.43, 2.05, and 2.26 times larger than those of Co(OH)2/rGO, Co3O4/rGO, and bare CoP. In particular, the CoP/rGO nanosheet arrays show the highest specific capacities among the monometallic phosphide-based nanostructures reported so far. The CoP/rGO retains 1198.9 C g-1 (2997.2 F g-1) at 10 A g-1, revealing the outstanding rate capability of 83%. Theoretical calculations reveal that rGO can adequately reduce the absorption energy of OH- on CoP, which makes CoP/rGO have strong adsorption capacity of OH-, resulting in boosting electrochemical performance. A hybrid supercapacitor of CoP/rGO/NF//AC was designed, which presents a superior energy density of 43.2 Wh kg-1 at a power density of 1010.5 W kg-1. After 10 000 cycles, the CoP/rGO/NF//AC supercapacitor reveals excellent cycling durability with a capacitance retention of 89%. This work provides a new insight into the design of high-performance electrode materials by combining high capacitive metal phosphides with conductive carbon, which is of great significance for energy storage systems.

MoSe2 nanoflakes-decorated vertically aligned carbon nanotube film on nickel foam as a binder-free supercapacitor electrode with high rate capability.

A new type of composite electrode material, MoSe2 nanoflakes grown on the vertically aligned carbon nanotube array film (VACNTF) with binder-free nickel foam as current collector (VACNTF@MoSe2/NF), was fabricated by a simple spraying chemical vapor deposition method combined with the solvothermal technique. Owing to the introduction of the VACNTF with ordered channels and appropriate intertube spacing, which facilitate electrolyte ions quickly transferring and alleviate the volume changes in the electrochemical measurements, the VACNTF@MoSe2/NF sample presents superior electrochemical performance compared to pure MoSe2/NF sample. The VACNTF@MoSe2/NF sample exhibits high specific capacitance of 435 F·g-1 at 1 A·g-1, remarkable cycling stability (92% of the original capacitance maintaining over 5000 cycles) and especially excellent rate capability (84.1% capacitance retention with the current density changed from 1 to 15 A·g-1). Moreover, the VACNTF@MoSe2/NF based asymmetric supercapacitor exhibits a high energy density with 22 Wh·kg-1 for a power density of 330 W·kg-1. This paper offers a new strategy to prepare transition metal dichalcogenides based electrode materials with high rate performance.

Doping effect and oxygen defects boost room temperature ferromagnetism of Co-doped ZnO nanoparticles: experimental and theoretical studies.

Co-doped ZnO nanoparticles with different dosage concentrations were fabricated by a thermal decomposition method. The nanoparticles show a pure wurtzite structure without the formation of a secondary phase or Co clusters, in which Co ions present as Co2+ and occupy Zn2+ tetrahedral sites within the ZnO matrix. All the samples show ferromagnetic properties at room temperature with nonzero coercivity and remanence magnetization. Besides, the magnetic data is also fitted by the model of bound magnetic polarons (BMP). By increasing the Co2+ doping concentration, the saturation magnetization values of Co-doped ZnO nanoparticles increase first and then decreases, which is related to the variation tendency of oxygen defects on the surface and the number of BMPs. This phenomenon can be ascribed to the formation of defect-induced BMPs, in which ferromagnetic coupling occurs at lower Co2+ concentration and Co2+-O2--Co2+ antiferromagnetic coupling arises at higher Co2+ concentration. Air annealing experiments further demonstrate this result, in which the saturation magnetization of Co-doped ZnO nanoparticles is reduced after annealing in Air. The doping effect and oxygen defects on the magnetic ordering of Co-doped ZnO were calculated using density functional theory. The calculation results reveal that stable long-range magnetic ordering in Co-doped ZnO nanoparticles is mainly attributed to the localized spin moments from 3d electrons of Co2+ ions. Both the experimental and theoretical studies demonstrate that the ferromagnetism in Co-doped ZnO nanoparticles is originated from the combined effects of Co doping and oxygen vacancies. These results provide an experimental and theoretical view to understand the magnetic origination and tune the magnetic properties of diluted magnetic semiconductors, which is of great significance for spintronics.

Hierarchical NiCo2S4@NiCoP core-shell nanocolumn arrays on nickel foam as a binder-free supercapacitor electrode with enhanced electrochemical performance.

A novel hierarchical core-shell nanocolumn array, with NiCo2S4 hollow nanowire (NiCo2S4 H-NW) as the core and NiCoP nanosheet (NiCoP NS) as the shell, has been directly synthesized on nickel foam (NF) as self-supported, binder-free electrode for high-performance supercapacitors. The morphological characterizations reveal that the diameter of NiCo2S4 H-NW core is ∼100 nm and the diameter of single NiCo2S4@NiCoP core-shell nanocolumn is ∼250 nm. Through a series of electrochemical tests and the analysis of charge storage kinetics, hierarchical NiCo2S4@NiCoP/NF electrode presents high areal specific capacitance of 5.98 F/cm2 at 1 mA/cm2, outstanding rate capability (70.29% capacitance retention with the current density increased from 1 to 50 mA/cm2) and superior cycling stability (92.94% of original capacity is retained after 5000 cycles at 10 mA/cm2). The prominent performance of NiCo2S4@NiCoP/NF electrode could be resulted from their unique hierarchical core-shell nanocolumn structure, which could offer abundant active sites near the interface for fast electrochemical reaction, and validly avoid the collapse of internal structure for the stability of whole structure in the repeated electrochemical measurement. The novel NiCo2S4@NiCoP/NF electrode offers a new method for future electrochemical energy storage devices with high-stability.

Crystalline-Amorphous Permalloy@Iron Oxide Core-Shell Nanoparticles Decorated on Graphene as High-Efficiency, Lightweight, and Hydrophobic Microwave Absorbents.

The exploration of high-efficiency microwave absorption materials with lightweight and hydrophobic features is highly expected to reduce or eliminate the electromagnetic pollution. Graphene-based nanocomposites are universally acknowledged as promising candidates for absorbing microwaves due to their remarkable dielectric properties and lightweight characteristic. However, the hydrophilicity of graphene may reduce their stability and restrict the applications in moist environment. Herein, a well-designed heterostructure composed of crystalline permalloy core and amorphous iron oxide shell was uniformly adhered on oleylamine-modified graphene nanosheets by a one-pot thermal decomposition method. Compared with the recognized hydrophilic graphene-based hybrid materials, the permalloy@iron oxide/graphene nanocomposites show excellent hydrophobic and water-resistant features with a water contact angle of 136.5°. Besides, the nanocomposites show high-efficiency microwave absorption performance, benefiting from the tunneling effect, polarization, interface interaction, impedance matching condition, and synergistic effect between core-shell permalloy@iron oxide nanoparticles and graphene nanosheets. A broad effective absorption bandwidth with reflection loss (RL) value exceeding -10 dB can be obtained from 4.25 to 18 GHz, covering about 86% measured frequency range when the absorber thickness is 2.0-5.0 mm. Also, the microwave absorption performance of nanocomposites can be tuned by changing the amount of graphene. More importantly, a greatly improved microwave absorption effectiveness of -71.1 dB can be achieved for the nanocomposites in comparison with the bare permalloy@iron oxide nanoparticles (-5.6 dB) and oleylamine-modified GO nanosheets (-3.56 dB). The lightweight and hydrophobic permalloy@iron oxide/graphene nanocomposites with high-efficiency microwave absorption performance are highly promising to improve the environmental adaptability of electric devices, especially in the wet environment.

Phosphorization boosts the capacitance of mixed metal nanosheet arrays for high performance supercapacitor electrodes.

Binary transition metal phosphides hold immense potential as innovative electrode materials for constructing high-performance energy storage devices. Herein, porous binary nickel-cobalt phosphide (NiCoP) nanosheet arrays anchored on nickel foam (NF) were rationally designed as self-supported binder-free electrodes with high supercapacitance performance. Taking the combined advantages of compositional features and array architectures, the nickel foam supported NiCoP nanosheet array (NiCoP@NF) electrode possesses superior electrochemical performance in comparison with Ni-Co LDH@NF and NiCoO2@NF electrodes. The NiCoP@NF electrode shows an ultrahigh specific capacitance of 2143 F g-1 at 1 A g-1 and retained 1615 F g-1 even at 20 A g-1, showing excellent rate performance. Furthermore, a binder-free all-solid-state asymmetric supercapacitor device is designed, which exhibits a high energy density of 27 W h kg-1 at a power density of 647 W kg-1. The hierarchical binary nickel-cobalt phosphide nanosheet arrays hold great promise as advanced electrode materials for supercapacitors with high electrochemical performance.

Synthesis and loading-dependent characteristics of nitrogen-doped graphene foam/carbon nanotube/manganese oxide ternary composite electrodes for high performance supercapacitors.

The ternary composite electrodes, nitrogen-doped graphene foam/carbon nanotube/manganese dioxide (NGF/CNT/MnO2), have been successfully fabricated via chemical vapor deposition (CVD) and facile hydrothermal method. The morphologies of the MnO2 nanoflakes presented the loading-dependent characteristics and the nanoflake thickness could also be tuned by MnO2 mass loading in the fabrication process. The correlation between their morphology and electrochemical performance was systematically investigated by controlling MnO2 mass loading in the ternary composite electrodes. The electrochemical properties of the flexible ternary electrode (MnO2 mass loading of 70%) exhibited a high areal capacitance of 3.03F/cm2 and a high specific capacitance of 284F/g at the scan rate of 2mV/s. Moreover, it was interesting to find that the capacitance of the NGF/CNT/MnO2 composite electrodes showed a 51.6% increase after 15,000 cycles. The gradual increase in specific capacitance was due to the formation of defective regions in the MnO2 nanostructures during the electrochemical cycles of the electrodes, which further resulted in increased porosity, surface area, and consequently increased electrochemical capacity. This work demonstrates a rarely reported conclusion about loading-dependent characteristics for the NGF/CNT/MnO2 ternary composite electrodes. It will bring new perspectives on designing novel ternary or multi-structure for various energy storage applications.

Well-defined flowerlike NdOCl nanostructures: nonaqueous sol-gel synthesis, nanoscale characterization and their magnetic and photoluminescence properties.

A facile nonaqueous solution route for the fabrication of NdOCl nanostructures based on a ligand-exchange protocol and further thermal decomposition in organic medium, using only chloride salt as the neodymium source, is reported and the formation mechanism is proposed. The morphology, crystal structure, and chemical compositions of the sample were characterized at the nanoscale. XRD results and selected-area electron diffraction patterns show that the sample is purely tetragonal NdOCl without any other impurity phases. TEM results show that the NdOCl nanostructures have a well-defined flowerlike shape, which looks like a chrysanthemum just about to bloom. Magnetization measurements reveal that the NdOCl nanoflowers show room-temperature ferromagnetism. The photoluminescence properties were also studied. These results are significant for fundamental research and promising applications of rare-earth-based nanostructures.

Effects of gas pockets on high-intensity focused ultrasound field.

The paper describes experimental and numerical studies of the effects of gas pockets on a high-intensity focused ultrasound (HIFU) field. Air bubbles ranging from 0.8 to 2.4 mm in radius were produced in transparent polyacrylamide tissue-mimicking gels. A single-element 3.5-MHz HIFU transducer was used to sonicate the gel phantoms. The changes in the HIFU beam pattern for air bubbles at different positions were visualized by the Schlieren method. Quantitative measurements of pressure at the HIFU focus by a calibrated needle hydrophone showed considerable reduction in the focal pressure with the presence of an air pocket. The presence of a single 1.2-mm-radius air bubble, at a 5 mm axial pre-focal position, reduced the focal intensity by 50% and increased the lateral focal dimension by 50%. For air bubbles at pre-focal position close to the focus, lesion formation was observed not at the theoretical focus, but in front of the air bubble and the air bubble became a barrier for the post-focal ultrasound propagation. The effects of reflection were simulated numerically and were compared with the experiments. The results can be used as guidelines for evaluation of potential safety concerns produced by trapped gas-pockets in various HIFU therapies.

A targeting method based on acoustic backscatter for treatment planning in tissue ablation using focused ultrasound.

High-intensity focused ultrasound (HIFU) is a therapeutic modality that can produce coagulative necrosis in biological tissue, noninvasively. This technique requires the determination of the focus of a HIFU transducer before treatment. We investigated a method to localize the focus based on the change in radio-frequency (RF) signal at HIFU intensity levels below the threshold for tissue damage. 2-D RF data were collected during the HIFU exposure at subablative intensity levels in ex vivo chicken tissue. The HIFU intensity was then increased to induce necrotic lesions in tissue, visualized as hyperecho in B-mode images, and the location of hyperecho was used to represent physical lesions, as established in our prior studies. Results showed that focal RF amplitude increased immediately after HIFU started at subablative intensity. The focus was clearly visualized in a 2-D map of the average rate of change (ARC) of RF amplitude. The 2-D difference between focus locations based on RF data and hyperecho was 1.92 +/- 1.02 mm (mean +/- standard deviation), with no statistically significant difference (axial: p = 0.50, lateral: p = 0.07, paired t -test). Histological analysis was also performed to examine structural change in tissue after HIFU exposure. The results indicated that ARC map could be used to determine the focus of a HIFU transducer at subablative intensity, and it has the potential to be used for HIFU treatment targeting.

An acoustic backscatter-based method for localization of lesions induced by high-intensity focused ultrasound.

Ultrasound B-mode visualization of lesions produced in soft tissues using high-intensity focused ultrasound (HIFU) has been shown to be challenging when there is no cavitation activity and, therefore, no hyperechogenecity in the focal region. We investigated a method for the visualization and localization of HIFU-induced lesions after HIFU delivery was complete based on the change in backscattered radio-frequency (RF) signals. A HIFU transducer was used with focal dimension of 8 mm by 2 mm working at 5 MHz. HIFU was applied at different intensities to produce lesions in ex vivo chicken breast, with or without the generation of hyperecho in B-mode images. We compared lesion locations obtained from our RF-processing method, from measurement of physical lesions after exposure and from the B-mode images, if exposures had resulted in hyperecho. The results showed that the RF amplitude decreased as a function of time immediately after stopping the HIFU exposure. The lesions were clearly visualized in two-dimensional (2-D) images of the decay rate of RF amplitude, no matter with or without hyperecho. In experiments with hyperecho, when comparing to physical lesion locations, there was no statistically significant difference in the localization accuracy between the RF-based and the hyperecho-based method (p = 0.76). In cases without hyperecho, the distance between RF-based locations and measured lesion locations was 3.37 +/- 1.59 mm (mean +/- standard deviation). The axial and lateral difference were 2.00 +/- 2.31 mm and 0.85 +/- 2.15 mm, respectively, and no statistically significant difference was found between lesion coordinates (axial: p = 0.37 and lateral: p = 0.15). We demonstrated the feasibility of our proposed RF-based method for the localization of HIFU-induced lesions immediately after HIFU treatment. Using the decay rate in RF amplitude as the signature of lesion formation, our method can detect lesion locations even without the appearance of hyperecho.

A localization method of lesions induced by High Intensity Focused Ultrasound based on acoustic backscatter change.

High Intensity Focused Ultrasound (HIFU) has been investigated as a therapeutic modality for many medical applications. We investigated a noninvasive technique for the localization of HIFU-induced lesions based on the change in backscattered radio frequency (RF) signals. HIFU was applied to chicken breast tissue and we compared lesion locations obtained from RF data with our processing method, from the dissected tissues after exposure, and from B-mode images if exposures had resulted in hyperecho. RF amplitude of the focal spot was found to decrease, even without hyperecho in B-mode images. No significant difference was found on localization accuracy between the RF-based and the hyperecho-based method (p=0.76). In cases without hyperecho, the distance between RF-based locations and measured physical lesion locations was 3.37 +/- 1.59 mm. The axial and lateral difference was 2.00 +/- 2.31 mm and 0.85 +/- 2.15 mm, respectively, and no statistically significant difference was found between lesion coordinates in the axial (p=0.37) and lateral (p=0.15) directions. Based on the ex vivo tissue experiments, we have demonstrated the feasibility of the proposed RF-based method for the localization of the center of HIFU-induced lesions.