Recently, a number of fast iteration methods for the solution of the structured linear system arising from the incompressible Navier-Stokes equations have been proposed by some authors. In order to ...evaluate the strong stability of these numerical algorithms, in this paper we deal with the structured backward error analysis for this type of structured linear system and present the explicit formula of the structured backward error. Based on the structured backward error, we perform some numerical experiments to compare the availability of some existing numerical algorithms.
A chestnut-like aroma is widely considered an important indicator of an excellent-quality green tea; however, the key odorants responsible for chestnut-like aroma have never been systematically ...studied and remain unknown. In this study, the aroma components of green teas and Chinese chestnuts were analyzed using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS), and 58 compounds were identified as common aroma components among green teas, boiled Chinese chestnuts, roasted Chinese chestnuts and raw Chinese chestnuts. Subsequently, 17 volatiles, including 3-methylbutanal, (E)-3-penten-2-one, ethylbenzene, heptanal, benzaldehyde, 2-pentylfuran, octanal, benzeneacetaldehyde, (E)-2-octenal, (E,E)-3,5-octadien-2-one, linalool, nonanal, (E)-2-nonenal, decanal, (Z)-hex-3-en-1-yl hexanoate, trans-β-ionone and (E)-nerolidol, were identified as the key odorants responsible for chestnut-like aroma based on the odor activity value (OAV) calculation method. Besides, the comparison of OAVs of key odorants between fresh tea leaves and finished teas indicated that all key odorants were present in fresh tea leaves and that their contents increased or decreased during tea processing. Moreover, the comparison between results of OAV and gas chromatography-olfactometry (GC-O) methods showed that ethylbenzene, heptanal, benzaldehyde, 2-pentylfuran, (E,E)-3,5-octadien-2-one, linalool, (Z)-hex-3-en-1-yl hexanoate and trans-β-ionone were the common identified compounds between the two methods. The identification of chestnut-like aroma in green teas will provide a theoretical basis for further research on the directional adjustment and control of tea aroma quality.
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•Volatiles of green teas and Chinese chestnuts were analyzed by GC × GC-TOFMS.•58 Compounds were identified as potential key odorants by statistical comparison.•17 Key odorants were determined by OAV calculation and validation analysis.•Key odorants showed different variation trends of contents during processing.•The GC-O analysis of green tea with chestnut-like aroma was performed.
Underwater autonomous navigation technology is a key link for AUV to complete various underwater missions successfully. In this paper, we have proposed a position correction model based on hybrid ...gated RNN, which does not need to establish a motion model like typical navigation algorithms, to avoid modeling errors in the navigation process. According to the low update rate of GPS and the slip data caused by the coverage of GPS antenna during the process of floating and diving, it does not meet the actual requirements of navigation and control. We proposed to use improved EKF and iSAM as the output of the training dataset to filter out GPS slips, then the position error is corrected at the same time. First, the normalized input sequence is fed to the two-layer hybrid gated RNN with BiLSTM output mode as sequence and LSTM output mode as last, and then the processed data is fed to the two fully connected layers with a dropout layer added in the middle. After that, the output of the position correction model can be obtained through the regression layer. To confirm the validity of the proposed model, we conducted sea trials to compare the proposed model with EKF and iSAM. The experimental results prove that the proposed position correction model performs better than EKF and iSAM in all aspects, and the correction model trained with iSAM is more effective than that trained with EKF.
The unprecedented coronavirus disease 2019 (COVID-19) epidemic has created a worldwide public health emergency, and there is an urgent need to develop an effective vaccine to control this severe ...infectious disease. Here, we find that a single vaccination with a replication-defective human type 5 adenovirus encoding the SARS-CoV-2 spike protein (Ad5-nCoV) protect mice completely against mouse-adapted SARS-CoV-2 infection in the upper and lower respiratory tracts. Additionally, a single vaccination with Ad5-nCoV protects ferrets from wild-type SARS-CoV-2 infection in the upper respiratory tract. This study suggests that the mucosal vaccination may provide a desirable protective efficacy and this delivery mode is worth further investigation in human clinical trials.
Abstract
The clinical applications of magnetic hyperthermia therapy (MHT) have been largely hindered by the poor magnetic-to-thermal conversion efficiency of MHT agents. Herein, we develop a facile ...and efficient strategy for engineering encapsulin-produced magnetic iron oxide nanocomposites (eMIONs) via a green biomineralization procedure. We demonstrate that eMIONs have excellent magnetic saturation and remnant magnetization properties, featuring superior magnetic-to-thermal conversion efficiency with an ultrahigh specific absorption rate of 2390 W/g to overcome the critical issues of MHT. We also show that eMIONs act as a nanozyme and have enhanced catalase-like activity in the presence of an alternative magnetic field, leading to tumor angiogenesis inhibition with a corresponding sharp decrease in the expression of HIF-1α. The inherent excellent magnetic-heat capability, coupled with catalysis-triggered tumor suppression, allows eMIONs to provide an MRI-guided magneto-catalytic combination therapy, which may open up a new avenue for bench-to-bed translational research of MHT.
Biological tissues, such as tendons or cartilage, possess high strength and toughness with very low plastic deformations. In contrast, current strategies to prepare tough hydrogels commonly utilize ...energy dissipation mechanisms based on physical bonds that lead to irreversible large plastic deformations, thus limiting their load‐bearing applications. This article reports a strategy to toughen hydrogels using fibrillar connected double networks (fc‐DN), which consist of two distinct but chemically interconnected polymer networks, that is, a polyacrylamide network and an acrylated agarose fibril network. The fc‐DN design allows efficient stress transfer between the two networks and high fibril alignment during deformation, both contributing to high strength and toughness, while the chemical crosslinking ensures low plastic deformations after undergoing high strains. The mechanical properties of the fc‐DN network can be readily tuned to reach an ultimate tensile strength of 8 MPa and a toughness of above 55 MJ m−3, which is 3 and 3.5 times more than that of fibrillar double network hydrogels without chemical connections, respectively. The application potential of the fc‐DN hydrogel is demonstrated as load‐bearing damping material for a jointed robotic lander. The fc‐DN design provides a new toughening mechanism for hydrogels that can be used for soft robotics or bioelectronic applications.
Tough hydrogels with low plastic deformations based on fibrillar connected double networks (fc‐DN) are presented. The efficient transfer of stress between the polyacrylamide and agarose fibril networks via chemical crosslinks and better fibril alignment under stretch result in high fracture strength and toughness (55 MJ m−3). The fc‐DN provides a new toughening strategy and application potential for load‐bearing soft devices.
Ultrasound (US)-driven sonodynamic therapy (SDT) has demonstrated wide application prospects in the eradication of deep-seated bacterial infections due to its noninvasiveness, site-confined ...irradiation, and high-tissue-penetrating capability. However, the ineffective accumulation of sonosensitizers at the infection site, the hypoxic microenvironment, as well as rapid depletion of oxygen during SDT greatly hamper the therapeutic efficacy of SDT. Herein, an US-switchable nanozyme system was proposed for the controllable generation of catalytic oxygen and sonosensitizer-mediated reactive oxygen species during ultrasound activation, thereby alleviating the hypoxia-associated barrier and augmenting SDT efficacy. This nanoplatform (Pd@Pt-T790) was easily prepared by bridging enzyme-catalytic Pd@Pt nanoplates with the organic sonosensitizer meso-tetra(4-carboxyphenyl)porphine (T790). It was really interesting to find that the modification of T790 onto Pd@Pt could significantly block the catalase-like activity of Pd@Pt, whereas upon US irradiation, the nanozyme activity was effectively recovered to catalyze the decomposition of endogenous H2O2 into O2. Such “blocking and activating” enzyme activity was particularly important for decreasing the potential toxicity and side effects of nanozymes on normal tissues and has potential to realize active, controllable, and disease-loci-specific nanozyme catalytic behavior. Taking advantage of this US-switchable enzyme activity, outstanding accumulation in infection sites, as well as excellent biocompatibility, the Pd@Pt-T790-based SDT nanosystem was successfully applied to eradicate methicillin-resistant Staphylococcus aureus (MRSA)-induced myositis, and the sonodynamic therapeutic progression was noninvasively monitored by photoacoustic imaging and magnetic resonance imaging. The developed US-switchable nanoenzyme system provides a promising strategy for augmenting sonodynamic eradication of deep-seated bacterial infection actively, controllably, and precisely.
Structural transformations and lattice expansion of oleate‐capped iron oxide nanocube superlattices are studied by time‐resolved small‐angle X‐ray scattering (SAXS) during solvent removal. The ...combination of conductor‐like screening model for real solvents (COSMO‐RS) theory with computational fluid dynamics (CFD) modeling provides information on the solvent composition and polarity during droplet evaporation. Evaporation‐driven poor‐solvent enrichment in the presence of free oleic acid results in the formation of superlattices with a tilted face‐centered cubic (fcc) structure when the polarity reaches its maximum. The tilted fcc lattice expands subsequently during the removal of the poor solvent and eventually transforms to a regular simple cubic (sc) lattice during the final evaporation stage when only free oleic acid remains. Comparative studies show that both the increase in polarity as the poor solvent is enriched and the presence of a sufficient amount of added oleic acid is required to promote the formation of structurally diverse superlattices with large domain sizes.
Time‐resolved small‐angle X‐ray scattering (SAXS) measurements of nanocube superlattices in evaporating droplets and the correlated experimental data to multi‐scale simulations are performed. With the presence of poor‐solvent and free oleic acid, a tilted face‐centered‐cubic (fcc) superlattice forms at maximum polarity. An unusual tilted face‐centered cubic to regular simple‐cubic (sc) lattice transformation with a 10% droplet volume increase occurs when only free oleic acid remains.
Under control: Controlled assemblies of gold nanorods in a poly(vinyl alcohol) (PVA) nanofiber matrix with tunable optical properties can be achieved by using electrospinning. The resultant ...assemblies can be used as substrates for surface‐enhanced Raman spectroscopy (SERS). This work provides a facile way to control alignment of anisotropic nanostructures in a polymer nanofiber matrix and generates new assemblies with interesting properties.
The strategy of combining a vaccine with immune checkpoint inhibitors has been widely investigated in cancer management, but the complete response rate for this strategy is still unresolved. We ...describe a genetically engineered cell membrane nanovesicle that integrates antigen self-presentation and immunosuppression reversal (ASPIRE) for cancer immunotherapy. The ASPIRE nanovaccine is derived from recombinant adenovirus-infected dendritic cells in which specific peptide-major histocompatibility complex class I (pMHC-I), anti-PD1 antibody and B7 co-stimulatory molecules are simultaneously anchored by a programmed process. ASPIRE can markedly improve antigen delivery to lymphoid organs and generate broad-spectrum T-cell responses that eliminate established tumours. This work presents a powerful vaccine formula that can directly activate both native T cells and exhausted T cells, and suggests a general strategy for personalized cancer immunotherapy.
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