SARS-CoV-2 variants could induce immune escape by mutations on the receptor-binding domain (RBD) and N-terminal domain (NTD). Here we report the humoral immune response to circulating SARS-CoV-2 ...variants, such as 501Y.V2 (B.1.351), of the plasma and neutralizing antibodies (NAbs) elicited by CoronaVac (inactivated vaccine), ZF2001 (RBD-subunit vaccine) and natural infection. Among 86 potent NAbs identified by high-throughput single-cell VDJ sequencing of peripheral blood mononuclear cells from vaccinees and convalescents, near half anti-RBD NAbs showed major neutralization reductions against the K417N/E484K/N501Y mutation combination, with E484K being the dominant cause. VH3-53/VH3-66 recurrent antibodies respond differently to RBD variants, and K417N compromises the majority of neutralizing activity through reduced polar contacts with complementarity determining regions. In contrast, the 242-244 deletion (242-244Δ) would abolish most neutralization activity of anti-NTD NAbs by interrupting the conformation of NTD antigenic supersite, indicating a much less diversity of anti-NTD NAbs than anti-RBD NAbs. Plasma of convalescents and CoronaVac vaccinees displayed comparable neutralization reductions against pseudo- and authentic 501Y.V2 variants, mainly caused by E484K/N501Y and 242-244Δ, with the effects being additive. Importantly, RBD-subunit vaccinees exhibit markedly higher tolerance to 501Y.V2 than convalescents, since the elicited anti-RBD NAbs display a high diversity and are unaffected by NTD mutations. Moreover, an extended gap between the third and second doses of ZF2001 leads to better neutralizing activity and tolerance to 501Y.V2 than the standard three-dose administration. Together, these results suggest that the deployment of RBD-vaccines, through a third-dose boost, may be ideal for combating SARS-CoV-2 variants when necessary, especially for those carrying mutations that disrupt the NTD supersite.
Microstructures with superior surface quality have been becoming more and more important in many fields. Various methods have been exploited to fabricate high quality microstructures. Among those ...approaches, wire electrochemical micromachining (WEMM) is an effective and efficient way to manufacture micro components. Generating passive film on the workpiece is an alternative to improve surface quality in WEMM, which necessitates a delicate selection of electrolyte. NaNO
3
solution as a passive electrolyte is beneficial to obtain good surface quality, but it barely takes effect in WEMM. Herein, an attempt is made to combine ethylene glycol (solvent) and NaNO
3
(solute) to investigate its influences on surface quality in WEMM of stainless steel (304 SS). Electrochemical measurements reveal that 304 SS is subjected to secondary passivation in 1 mol/L NaNO
3
-ethylene glycol. X-ray photoelectron spectroscopy analysis indicates that the compositions of the passive films formed at various potentials are not exactly the same. Both the secondary passivation and the passive films make dramatic contributions to the improvement of the machined surface quality. Experimental results demonstrate that surface roughness achieved with ethylene glycol is Ra = 0.034 μm, noticeably smaller than that with traditional acid solutions. Finally, microstructures with ultra-smooth surfaces are fabricated on the 304 SS plate.
In this study, water soluble CuO nanostructures having nanobelt, nanorod, or spindle morphologies were synthesized using aqueous solutions of Cu(NO
3
)
2
·3H
2
O and NaOH by adjusting the type of ...surface modifier and reaction temperature. The effect of morphologies of these various CuO nanostructures as water-based lubricant additives on tribological properties was evaluated on a UMT-2 micro-friction tester, and the mechanisms underlying these properties are discussed. The three different morphologies of CuO nanostructures exhibited excellent friction-reducing and anti-wear properties. Tribological mechanisms differed in the initial stage of frictional interactions, but in the stable stage, a tribochemical reaction film and adsorbed lubricious film on the rubbing surfaces played important roles in hindering direct contact between friction pairs, leading to improved tribological properties.
Abstract
The titanium alloy Ti-6Al-4V is used in many industries including aviation, automobile manufacturing, and medical equipment, because of its low density, extraordinary corrosion resistance ...and high specific strength. Electrochemical machining (ECM) is a non-traditional machining method that allows applications to all kinds of metallic materials in regardless of their mechanical properties. It is widely applied to the machining of Ti-6Al-4V components, which usually takes place in a multicomponent electrolyte solution. In this study, a 10% NaNO
3
solution was used to make multiple holes in Ti-6Al-4V sheets by through-mask electrochemical machining (TMECM). The polarization curve and current efficiency curve of this alloy were measured to understand the electrical properties of Ti-6Al-4V in a 10% NaNO
3
solution. The measurements show that in a 10% NaNO
3
solution, when the current density was above 6.56 A·cm
−2
, the current efficiency exceeded 100%. According to polarization curve and current efficiency curve, an orthogonal TMECM experiment was conducted on Ti-6Al-4V. The experimental results suggest that with appropriate process parameters, high-quality holes can be obtained in a 10% NaNO
3
solution. Using the optimized process parameters, an array of micro-holes with an aperture of 2.52 mm to 2.57 mm and maximum roundness of 9 μm were produced using TMECM.
The formation of a tribo-film on the counterface plays an important role on the tribological performances of polymer subjected to mixed and boundary lubrication conditions. However, when freshwater ...is used as a lubricant, the formation of a tribo-film usually is hindered. In order to overcome this disadvantage, PEEK/α-FeOOH nanocomposites were developed and their tribological performances were studied under water lubrication conditions in the present work. It was demonstrated that the inclusion of α-FeOOH nanoparticles (NPs) into the PEEK matrix improves significantly the tribological performance of the matrix. The nanostructures and properties of the tribo-films formed on the steel counterface were comprehensively studied. It was identified that the addition of α-FeOOH NPs promotes the formation of a lubricating tribo-film which covers the entire counterface. Based on the investigations on tribo-films, we deem that the α-FeOOH NPs act as precursors for the dehydration reaction promoting the formation of a tribo-film which consists of α-Fe
2
O
3
and transferred PEEK. It is assumed that the enhanced tribological performance is related to the possibly high load-bearing capability and "easy-to-shear" characteristic of the tribo-film.
Addition of α-FeOOH nanoparticles into PEEK matrix promotes the formation of a lubricating tribo-film on the sliding counterface exposed to water-lubrication and thereby, the tribological performance is greatly improved.
This detailed the tribological and tribochemical properties of magnetite（Fe3O4） nanoflakes used as additives in #40 base oil in a four-ball tribo-tester.The average friction coefficient of the ...friction pair for lubricant containing the Fe3O4 nanoflakes of 1.5 wt%as a lubricant additive in the base oil is decreased by18.06%compared to that of solely base oil.The chemical composition of base oil with the Fe3O4 nanoflake additives did not change during the 48-h friction assessment.The decreased saturation magnetization and increased coercivity of magnetite nanoflakes occurred due to the distortion of the basal planes and the presence of hematite（α-Fe3O4） generated by the tribochemical reactions during the friction process.The multi-layer low-shear-stress tribochemical lubrication films on the surface of the friction pair could form because the nanoflake particles arrange and adhere onto the surface of the friction pair in an orderly manner,and the tribochemical reactions of the friction pair in the presence of the nanoflakes occur as Fe→FeO→Fe3O4→γ-FeOOH →γ-Fe2O3→α-Fe2O3.The formation of the films can improve the tribological properties.
Objective
To evaluate the efficacy of the CT-based intratumoral, peritumoral, and combined radiomics signatures in predicting progression-free survival (PFS) of patients with chondrosarcoma (CS).
...Methods
In this study, patients diagnosed with CS between January 2009 and January 2022 were retrospectively screened, and 214 patients with CS from two centers were respectively enrolled into the training cohorts (institution 1,
n
= 113) and test cohorts (institution 2,
n
= 101). The intratumoral and peritumoral radiomics features were extracted from CT images. The intratumoral, peritumoral, and combined radiomics signatures were constructed respectively, and their radiomics scores (Rad-score) were calculated. The performance of intratumoral, peritumoral, and combined radiomics signatures in PFS prediction in patients with CS was evaluated by C-index, time-dependent area under the receiver operating characteristics curve (time-AUC), and time-dependent C-index (time C-index).
Results
Eleven, 7, and 16 features were used to construct the intratumoral, peritumoral, and combined radiomics signatures, respectively. The combined radiomics signature showed the best prediction ability in the training cohort (C-index, 0.835; 95%; confidence interval CI, 0.764–0.905) and the test cohort (C-index, 0.800; 95% CI, 0.681–0.920). Time-AUC and time C-index showed that the combined signature outperformed the intratumoral and peritumoral radiomics signatures in the prediction of PFS.
Conclusion
The CT-based combined signature incorporating intratumoral and peritumoral radiomics features can predict PFS in patients with CS, which might assist clinicians in selecting individualized surveillance and treatment plans for CS patients.
Critical relevance statement
Develop and validate CT-based intratumoral, peritumoral, and combined radiomics signatures to evaluate the efficacy in predicting prognosis of patients with CS.
Key points
• Reliable prognostic models for preoperative chondrosarcoma are lacking.
• Combined radiomics signature incorporating intratumoral and peritumoral features can predict progression-free survival in patients with chondrosarcoma.
• Combined radiomics signature may facilitate individualized stratification and management of patients with chondrosarcoma.
Graphical Abstract
The aim of this paper was to investigate the tribological properties of magnetite (Fe
3
O
4
) nanoparticles (NPs) with various morphologies (i.e., hexagonal, octahedral, and irregular morphologies) ...utilized as lubricating additives on a four-ball tribo-tester. The diameters of wear scar and the friction coefficients were measured using a scanning electron microscope (SEM) and a statistical software, respectively. The properties of the friction pair surfaces were examined by a SEM, atomic force microscope, energy dispersive X-ray spectroscope, and X-ray photoelectron spectroscope. The results show that the Fe
3
O
4
NPs, especially the NPs with hexagonal morphology, have superior antifriction properties as lubricating additives. In addition, the antifriction mechanism of the Fe
3
O
4
NPs as lubricating additives was also discussed.
In order to avoid occurrence of severe seizure of motion components exposed to mixed and boundary lubrication, e.g., in engine and transmission systems, to replace metal–metal friction pairs by ...polymer–metal pairs provides a potential solution. In the present work, the tribological behaviors of short carbon fiber (SCF)-reinforced epoxy (EP) composites when lubricated with polyalphaolefin base oil were investigated. It was identified that the running-in tendency and friction coefficient of the composites show a close dependence on the lubrication regimes. SCF improves greatly the wear resistance of EP although they increase slightly the friction coefficient. It was demonstrated that further addition of monodispersed SiO
2
nanoparticles into the EP composite filled with SCF and graphite leads to higher wear resistance. The reinforcement of SCF and the formation of a high-performance tribofilm on the surface of steel counterpart play an important role on the tribological properties of EP-based materials.
Superhydrophilicity has been widely used in industrial applications. Superhydrophilic metal surfaces are subject to becoming superhydrophobic when exposed in air, which is due to the accumulation of ...airborne organics on the surfaces. This wettability transition disables the desired functions and causes dramatic inconvenience in industrial applications. Therefore, a nondestructive treatment method is needed to recover the original superhydrophilicity. Herein, an electrolysis-assisted method is proposed to realize the recovery of wettability in which the metal surfaces are used as cathode in the electrolysis processing system. Bubbles resulted from electrolysis can effectively and efficiently remove the airborne organics absorbed on the surfaces, resulting in the recovery of superhydrophilicity. In addition, it is experimentally verified that this method can also be used to get rid of the low energy substances such as fluoroalkylsilaneis, from the chemically-treated superhydrophobic surfaces. What's more, the hierarchical microstructures and substrates are free of damage. The method can be repeatedly employed for the recovery of superhydrphilicity whenever the superhydrophilic surfaces are superhydrophobized. Notably, as far as we have investigated, this approach can be applied to metal materials such as Al, Ni, W, Ti, Cu and stainless steel.
•Electrolysis can recover the original superhydrophilicity.•The method can remove low energy substances from superhydrophobized surfaces.•It can be applied to many metal materials including Al, Fe, Cu, Ni, W and Ti.
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