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•The preparation of pristine MXenes and MXenes hybrids are systematically summarized.•Green, efficient, and widely available synthetic routes are specifically highlighted.•The ...structure, microstructure and electronic structure of MXene are clearly revealed.•Microwave dielectric properties and attenuation mechanism are objectively reviewed.•Numbers research works on MXenes for MA and EMI shielding are demonstrated.
MXene, a shining star of two-dimensional (2D) materials, perfectly showcases layered structure, outstanding electrical conductivity, tunable active surface, and excellent mechanical strength, all of which make it extremely attractive in various applications, in particular for the ever growing market of microwave absorption (MA) and electromagnetic interference (EMI) shielding technology. Herein, we introduce the synthetic strategies, structure and properties of MXene-based materials. The current research progresses on the dielectric properties of MXene are comprehensively summarized and analyzed. We objectively overview and evaluate the state-of-the-art in electromagnetic wave absorbing and shielding of MXene-based matrials and dissect the major problems and bottlenecks. In addition, prospective research opportunities are highlighted toward the development of advanced MXene-based materials for MA and EMI shielding.
Delaminated Ti3C2Tx (D-Ti3C2Tx) MXene films exhibit excellent electrochemical and electromagnetic interference (EMI) shielding performance. However, the low yield and easy oxidation of D-Ti3C2Tx ...nanosheet limit its commercial application. Herein, the flexible green multilayered Ti3C2Tx/hydroxyethyl cellulose (M-Ti3C2Tx/HEC) composite film was successfully fabricated through the filtration assisted self-assembly of M-Ti3C2Tx together with HEC. The film shows good cyclability as electrode materials for energy storage devices, which is mainly attributed to the construction of interconnected structures, where HEC was bonded to M-Ti3C2Tx. The electron migration and surface group play important roles in the process of charging and discharging. Meanwhile, the film shows excellent EMI shielding performance. Especially, dielectric loss analysis indicates that EM waves entering the film are mainly dissipated in the form of heat energy caused by electron migration. The effect of multilayer stacking indicates that the film present the trend of absorption-dominate green EMI shielding with the decrease of the stacking thickness. This work will provide new ideas for accelerating the utilization of the MXene-based energy storage and green EMI shielding materials.
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•We fabricate flexible green M-Ti3C2Tx MXene/HEC film that possesses excellent EMI shielding performance and good cyclability.•The conductive network constructed by M-Ti3C2Tx plays an important role in the process of charging and discharging.•Dielectric loss analysis indicates that EM waves entering the film are mainly dissipated in the form of heat energy.•The thicker the stacking thickness, the more contribution to EMI shielding will be from reflection.•A novel strategy is found to tune conductive network for energy storage and electromagnetic shielding.
A nickel-catalyzed benzylic substitution of secondary phosphine oxide was described, affording the dialkylated P-stereogenic tertiary phosphine oxides with high to excellent enantioselectivities. The ...reaction was performed under mild conditions with commercially available benzyl chlorides and bench stable secondary phosphine oxides, exhibiting broad functional group tolerance. It represented a practical example for the preparation of P-stereogenic phosphine compounds.
The phase-to-ground admittance in distribution networks is asymmetric. This asymmetry is aggravated by the arc suppression coil, resulting in zero-sequence overvoltage. The magnitude of zero-sequence ...overvoltage can exceed the line-to-ground voltage, endangering the operation of electrical equipment. Moreover, after the occurrence of a single-line-to-ground fault, the change law of the three-phase voltage is affected by the zero-sequence overvoltage, leading to misjudgment of the fault phase. Accordingly, this paper proposes a fault phase selection method based on active current injection that can adapt to asymmetric distribution networks. The fault phase is selected by injecting current and calculating the equivalent power supply voltage of the faulty line without increasing the ground-fault current. The high sensitivity of the proposed fault phase selection method was verified for high impedance faults through software simulations and prototype experiments. Moreover, the zero-sequence overvoltage can be suppressed by a single-phase flexible arc suppression device during the normal operation of distribution networks. The ground-fault current can be quickly suppressed at different ground-fault locations and resistance values, ensuring the extinguishment of the ground-fault arc.
•A simple method has been successfully applied to the preparation of MXene-CNT/PANI ternary composite.•MXene makes the CNT/PANI disperse uniformly, achieving good electrical conductivity and facile ...ion diffusion pathway.•MXene-CNT/PANI electrode has superior gravimetric capacity and cyclic stability.
MXene is considered a promising two-dimensional (2D) material with excellent conductivity, and it has been proved to be a potential material for supercapacitor electrode. However, the supercapacitive performances of the pristine MXene are always not satisfactory due to the innate re-stacking tendency of the MXene nanosheets. In this work, the carbon nanotubes/polyaniline (CNT/PANI) nanocomposite was introduced and obtained MXene-CNT/PANI ternary composite electrode. Thanks to the synergy between each component, MXene-CNT/PANI exhibited enhanced specific capacitance that reached 429.4 F/g at 1A/g, which is completely better than that of any single compound in the ternary material. Besides, this ternary composite electrode holds a high stable cycle performance with over 93% retention after 10,000 cycles. Furthermore, a quantitative analysis was also carried out to prove the relationship between the capacitive contribution and the scan rate of the MXene-CNT/PANI.
BACKGROUND
Sturgeon is popular for its nutritious value and its taste. However, sturgeon fillets are traditionally heated in 100 °C boiling water, resulting in unfavorable taste and with a negative ...effect on the quality. This study considered the effect of combinations of vacuum and low‐temperature treatments (LTVH groups) on sturgeon fillets compared with the traditional heat treatment (TC groups).
RESULTS
The results show that the LTVH groups had lower cooking‐loss rates. All LTVH fillets were changed to a white color, and appeared ‘done’, as did the TC fillets. The LTVH and TC methods gave rise to significant differences in texture: the springiness of the LTVH groups decreased with heating time, and decreased rapidly in the TC groups (P < 0.05); hardness and chewiness increased with time and temperature in the LTVH groups, but decreased in the TC groups. More compact and denser gaps were observed in LTVH70 groups and TC groups. Less protein and lipid oxidation was evident in LTVH groups, including more myofibril protein solubility; there was less protein aggregation, fewer thiobarbituric acid reactive substance, and Schiff base.
CONCLUSION
Vacuum and low‐temperature treated sturgeon fillets can be served as a good alternative. This treatment caused slight tissue damage and less proteolysis and lipid oxidation, which is beneficial for the quality of aquatic products.
Esophageal squamous cell carcinoma (ESCC) is among the most common malignancies, but little is known about its spatial intratumoral heterogeneity (ITH) and temporal clonal evolutionary processes. To ...address this, we performed multiregion whole-exome sequencing on 51 tumor regions from 13 ESCC cases and multiregion global methylation profiling for 3 of these 13 cases. We found an average of 35.8% heterogeneous somatic mutations with strong evidence of ITH. Half of the driver mutations located on the branches of tumor phylogenetic trees targeted oncogenes, including PIK3CA, NFE2L2 and MTOR, among others. By contrast, the majority of truncal and clonal driver mutations occurred in tumor-suppressor genes, including TP53, KMT2D and ZNF750, among others. Interestingly, phyloepigenetic trees robustly recapitulated the topological structures of the phylogenetic trees, indicating a possible relationship between genetic and epigenetic alterations. Our integrated investigations of spatial ITH and clonal evolution provide an important molecular foundation for enhanced understanding of tumorigenesis and progression in ESCC.
Due to the widespread use of broad-spectrum antibiotics, the morbidity of prostate abscesses (PA) has declined dramatically. However, under special circumstances, such as invasive procedures and ...immunosuppressive conditions, some patients are more likely to develop this disease. Here, we present the case of a 21-year-old man, diagnosed with PA, with a history of chronic steroid use and a long-term indwelling urinary catheter. The pathogen was confirmed as carbapenem-resistant Klebsiella pneumoniae, a rare bacterium. This case indicates that immunodeficiency and invasive catheter use may be risk factors for PA and opportunistic bacterial infections.
A 21-year-old young man presented with sudden onset of high fever (39.7°C). The patient had a history of long-term use of steroids and long-term indwelling urinary catheter. Digital rectal examination revealed obvious swelling and tenderness of the prostate. Subsequent pelvic magnetic resonance imaging showed a high signal lesion measuring 2.1 × 2.9 × 2.8 cm with T1 enhancement and T2 enhancement.
On the 8th day of hospitalization, the patient underwent a PA drainage procedure and a pus culture was conducted. Subsequent pus and urine cultures showed the presence of Klebsiella pneumoniae, which exhibited resistance to all injectable carbapenems, cephalosporins, aminoglycosides, piperacillin-tazobactam, and quinolone drugs.
On the 8th day of hospitalization, the patient underwent PA drainage surgery under general anesthesia to drain the abscess and relieve obstruction. After the surgery, the patient received a 2-week treatment of doxycycline.
Finally, the patient was discharged after recovery and did not experience recurrence during the 6-month follow-up period.
PA is not commonly found, but some patients are more susceptible to this disease under certain host conditions. Immunodeficiency and invasive catheter use may be risk factors for PA and opportunistic bacterial infections. The use of omadacycline for the treatment of carbapenem-resistant Klebsiella pneumoniae infections appears to be effective.
Spinel transition metal oxide is a promising pseudocapacitive materials but the instability gives it narrow practical application. It is shown herein, that an effective remedy for these problems can ...be achieved by introducing highly conductive two dimensional (2D) reduced graphene oxide (rGO) substrate on which NiFe2O4 nanoparticles are well distributed. The rGO-NiFe2O4 hybrids with different NiFe2O4 contents were tailored to explore the source of the improvement in capacitance performance. It is found that rGO nanosheets in the hybrid can be used as a conductive substrate to accelerate the electron transport. Moreover, NiFe2O4 nanoparticles with a certain volume can simultaneously prevent the restacking of rGO and increase the pseudocapacitance. The G-N3 (30 wt% NiFe2O4) hybrid holds enhanced specific capacitance up to 210.9 F g−1 at 0.5 A g−1 far above that of pristine NiFe2O4 (50 F g−1), and exhibits superior cycle stability with no obvious capacity loss even after 5000 cycles. This research indicates that a tailoring method can promote the electrochemical performance of NiFe2O4, and hopefully accelerate the commercialization of spinel transition metal oxides as electrode materials for supercapacitor.
•Precisely regulated structures of rGO-NiFe2O4 nanohybrids are successfully achieved.•Island-like distributed NiFe2O4 can avoid stacking of rGO and aggregation of NiFe2O4.•Good electron conductivity and facile ion diffusion were achieved simultaneously.•The gravimetric capacity of hybrids electrode is four times that of pure NiFe2O4.
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