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1.
Mol Phylogenet Evol ; 178: 107633, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36182051

RESUMO

Bolbitis is a pantropical fern genus of Dryopteridaceae with ca. 80 species mainly in tropical Asia. Earlier studies confirmed the monophyly of Bolbitis when Mickelia is excluded and identified three major clades in Bolbitis. However, earlier studies are based on relatively small sampling and the majority of Asian species are not sampled. In this study, DNA sequences of three plastid markers of 169 accessions representing ca. 68 (85 % of total) species of Bolbitis in nine out of the 10 series recognized by Hennipman (1977), and 54 accessions representing the five remaining bolbitidoid genera are used to infer a global phylogeny with a focus on Asian species. The major results include: (1) Bolbitis is strongly supported as monophyletic; (2) species of Bolbitis are resolved into four major clades and their relationships are: the Malagasy/Mascarene clade is sister to the rest, followed by the African clade which is sister to the American clade + the Asian clade; (3) six well-supported subclades are identified in the most speciose Asian clade; (4) the free-veined Egenolfia is embedded in Bolbitis and is paraphyletic in relation to species with anastomosing venation; (5) three series sensu Hennipman (1977), B. ser. Alienae, B. ser. Egenolfianae, and B. ser. Heteroclitae, are paraphyletic or polyphyletic; (6) evolution of six morphological characters is analyzed and free venation is found to have evolved from anastomosing venation and reversed to free venation in Bolbitis; and (7) biogeographical implications are drawn and it is shown that a single recent dispersal from Asia resulted in continental disjunction of closely related ferns of Bolbitis between Africa and America.


Assuntos
Dryopteridaceae , Gleiquênias , Filogenia , Plastídeos/genética , Sequência de Bases
2.
J Colloid Interface Sci ; 629(Pt A): 640-648, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36088706

RESUMO

Accelerating the sluggish anode reaction in a Zn-air battery can improve its energy efficiency, but the large-scale development of this battery is hindered by the lack of bifunctional catalysts. Herein, we designed a one-step carbonization strategy for synthesizing monodispersed Co nanoparticles supported on N-doped carbon nanotube (Co/CNT), which shows excellent bifunctional electrocatalytic performance with long-term durability for oxygen reduction reaction/oxygen evolution reaction. The formation of carbon substrates from the carbonization of nitrogenous organic molecules are benefit to capture more Co nanoparticles though strong metal-substrate interaction, then construct high-density effective active sites of the Lewis base for accelerating the electrocatalytic reaction process. To verify its superior performance, a rechargeable Zn-air battery with a Co/CNT air electrode was subsequently constructed. The battery exhibits an open-circuit voltage of 1.41 V and a specific discharge capacity of 835.2 mAh/gZn, which can be continuously charged and discharged with good cycle stability. Our study provides a new strategy for developing various practical carbon-based non-noble metallic bifunctional electrocatalysts with promising performance in electrocatalysis and batteries to achieve the target of carbon neutrality.

3.
Food Chem ; 401: 134140, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36108384

RESUMO

Commercial immunochromatographic assay (ICA) is a convenient tool for controlling antibiotic abuse. Although great efforts have been made to improve the detection performance and quantitative capabilities, simplify the manufacturing process of commercial ICA is rarely mentioned. Here, a proof-of-principle work are developed to solve the above problem. Inspired by dyestuff chemistry, we developed an instant immune-network label strategy by dynamic protonation capacity of neutral red (NR), achieving a desirable labeling efficiency (<1min), and applying for ICA detection of chloramphenicol (CAP). Benefits from the efficiently protonation of NR, lengthy probe production time and organic reagents can be avoided, displaying excellent strip production efficiency and detection performance. Eventually, this strategy presents a visual limit of detection (vLOD) at 3 ng/mL, cut-off value is 9 ng/mL. The assay recoveries in milk and honey were 74.45-107.15 %, with the total RSD of 1.62-6.90 %. We envision that this strategy raises the possibility of commercializing of laboratory prototype products.


Assuntos
Antibacterianos , Cloranfenicol , Cloranfenicol/análise , Vermelho Neutro , Cromatografia de Afinidade/métodos , Limite de Detecção , Antibacterianos/análise , Imunoensaio/métodos
4.
Food Chem ; 403: 134465, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36358082

RESUMO

This study investigated the impacts of individual emulsifiers on the physicochemical stability, antioxidant ability, and in vitro digestion behavior of lutein-loaded nanostructured lipid carriers (NLCs). NLCs particles stabilized by ethyl lauroyl arginate, rhamnolipid, or tea saponin were fabricated by high-pressure microfluidization method. Differential scanning calorimetry and X-ray diffraction results confirmed the regulatory effect of emulsifiers on the crystallization behavior of NLCs. NLCs stabilized by rhamnolipid presented higher encapsulation efficiency (94.73%) for lutein than those stabilized by tea saponin (90.39%) or ethyl lauroyl arginate (88.86%). Meanwhile, the stability of embedded lutein during storage or photothermal treatments was greatly enhanced. Individual emulsifiers, together with lutein, endowed NLCs with excellent antioxidant capacity. During in vitro digestion, rhamnolipid-stabilized NLCs showed the slowest release of free fatty acids (50.87%) and provided an optimal sustained release for lutein with relatively high bioaccessibility (23.01%).


Assuntos
Nanoestruturas , Saponinas , Antioxidantes , Portadores de Fármacos/química , Luteína , Lipídeos/química , Tamanho da Partícula , Nanoestruturas/química , Emulsificantes/química , Chá
5.
Drug Discov Today ; : 103436, 2022 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-36370993

RESUMO

Natural killer (NK) cell therapy is emerging as a cancer treatment. NK cells are innate cytotoxic lymphocytes that act as first-line responders to kill target cells without prior encounters. NK cells recognize cancer cells, virus-infected cells, and other types of stressed cell through a reservoir of germline-encoded receptors. NK cells are safe for allogeneic applications. Therefore, they are the ideal off-the-shelf cell, which overcome the low efficiency issue caused by the patient-by-patient nature of autologous cell therapy. Unlike T cells, NK cells cannot form a strong immune memory; therefore, they suffer from short in vivo persistence. However, different from T cells, NK cells have a reservoir of innate immune receptors targeting a variety of malignant cells. In addition, they can utilize antibody guidance in target recognition. With suitable engineering, NK cells can function as universal anticancer drugs that are not restricted to HLA and cancer types, which will benefit the large cohort of patients with rare cancer types and patients with no convenient drug targets for precision and personalized medicine. Here, we summarize and discuss the designs of current anticancer NK cell therapies.

6.
Front Plant Sci ; 13: 1022476, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36388555

RESUMO

Edeines are a group of non-ribosomal antibacterial peptides produced by Brevibacillus brevis. Due to the significant antibacterial properties of edeines, increasing edeine yield is of great interest in biomedical research. Herein, we identified that EdeB, a member of the ParB protein family, significantly improved edeine production in B. brevis. First, overexpression of edeB in B. brevis X23 increased edeine production by 92.27%. Second, in vitro bacteriostasis experiment showed that edeB-deletion mutant exhibited less antibacterial activity. Third, RT-qPCR assay demonstrated that the expression of edeA, edeQ, and edeK, which are key components of the edeine biosynthesis pathway, in edeB-deletion mutant X23(ΔedeB) was significantly lower than that in wild-type B. brevis strain X23. Finally, electrophoretic mobility shift assay (EMSA) showed that EdeB directly bound to the promoter region of the edeine biosynthetic gene cluster (ede BGC), suggesting that EdeB improves edeine production through interaction with ede BGC in B. brevis.

7.
Front Surg ; 9: 971030, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36386510

RESUMO

Background: As neoadjuvant chemotherapy is widely used in breast cancer patients, the lymph node ratio has not been fully validated as a prognostic indicator of breast cancer received neoadjuvant chemotherapy. This study was conducted to investigate the prognostic value of lymph node ratio in breast cancer patients received neoadjuvant chemotherapy. Methods: Systematic searches were performed in the PubMed, Embase, and Cochrane Library databases until 15 December 2021 for studies on the association between lymph node ratio and the prognosis of breast cancer after neoadjuvant chemotherapy. Overall survival and disease-free survival were used as outcome events, and hazard ratio was chosen as the parameter to evaluate the correlation. The dose-response relationship was assessed by restricted cubic splines. In the subgroup analyses, which were used to explore potential heterogeneity among the included studies according to study region and sample size. Sensitivity analysis was performed to assess the stability of individual studies, and publication bias was determined with funnel plots, Begg's test, and Egger's test. All statistical analyses were performed using Stata 15.1. Results: A total of 12 studies with 4,864 patients were included in this meta-analysis. In this study, high lymph node ratio was significantly associated with decreased overall survival (HR: 4.74; 95%CI: 3.36-6.67; P < 0.001) and disease-free survival (HR: 4.77; 95%CI: 3.69-6.17; P < 0.001). Moreover, the dose-response meta-analysis showed a linear association between higher lymph node ratio and shorter overall survival and disease-free survival in breast cancer patients after neoadjuvant chemotherapy. Conclusions: The meta-analysis suggested that high lymph node ratio was significantly associated with short overall survival and disease-free survival in breast cancer patients after neoadjuvant chemotherapy. Therefore, lymph node ratio is an independent predictive factor for the prognosis of breast cancer patients after neoadjuvant chemotherapy, which may better refine the cancer staging system.

8.
Front Oncol ; 12: 1025177, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36387209

RESUMO

Objective: The efficacy of High Intensity Focused Ultrasound Ablation(HIFU) combined with Transhepatic Arterial Chemotherapy And Embolization(TACE) versus TACE alone in the treatment of hepatoma was evaluated by meta-analysis and trial sequential analyses(TSA). Methods: Pubmed, Cochrane, Embase, Web of Science, Scoups and CNKI, CQVIP, Wanfang Data(China National Knowledge Infrastructure) databases were searched from database construction to April 2022, and randomized controlled trials were included. Revman and Stata software were used for meta-analysis of tumor changes, survival rate, laboratory indicators and adverse reactions in the included studies, and TSA0.9 was used for sequential analysis. Grade Pro was also used to evaluate the included indicators. Results: Twelve studies were included with a sample size of 1025 cases. Meta-analysis showed that the tumor response rate in the combined treatment group was 1.54 times higher than that in TACE alone (OR: 2.54; 95%CI:1.81-3.57) and the 6-month to 5-year survival rate was 1-4 times higher, with statistically significant differences (P<0.05). Subgroup analysis showed that country, pathological type and study type were the sources of heterogeneity. Egger results showed that there was no publication bias (95%CI: -1.333, 3.552; Ppublication=0.276), and the sensitivity analysis results were reliable. TSA results suggest that there may be false positive results, which need to be further confirmed by more studies. Grade evaluation results indicated that the quality of evidence for response rate and one-year survival was low. Conclusion: HIFU combined with TACE has better efficacy in the treatment of hepatoma, which is worthy of promotion. However, there may be false positive results in this study, which needs to be further verified by more extensive and more tests.

9.
Artigo em Inglês | MEDLINE | ID: mdl-36395137

RESUMO

Spectral clustering (SC) has been widely used in many applications and shows excellent performance. Its high computational cost limits its applications; many strategies including the anchor technique can partly alleviate the high computational cost problem. However, early methods ignore the fact that SC usually involves two stages: relaxation and postprocessing, i.e., it relaxes the discrete constraints to continuous constraints, and then conducts the postprocessing to get the discrete solution, which is time-consuming and deviates from directly solving the primal problem. In this article, we first adopt the bipartite graph strategy to reduce the time complexity of SC, and then an improved coordinate descent (CD) method is proposed to solve the primal problem directly without singular value decomposition (SVD) and postprocessing, i.e., directly solving the primal problem not approximately solving. Experiments on various real-world benchmark datasets show that the proposed method can get better solutions faster with better clustering performance than traditional optimization methods. Furthermore, it can jump out of local minima of traditional methods and continue to obtain better local solutions. Moreover, compared with other clustering methods, it also shows its superiority.

10.
Front Surg ; 9: 1049260, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36406348

RESUMO

Objective: To evaluate the efficacy, safety, feasibility and biomechanical stability of contralateral bridge fixation of freehand minimally invasive pedicle screws (Freehand MIPS) combined with unilateral minimally invasive surgery-transforaminal lumbar interbody fusion (MIS-TLIF) (smile-face surgery) and open TLIF for the treatment of multi-segmental lumbar degenerative diseases (LDDs). Methods: From January 2013 to January 2016, clinical data of multi-segmental (2- or 3-level) LDDs receiving smile-face surgery or open TLIF were retrospectively collected and analyzed. The back and leg pain VAS and ODI were used to assess clinical outcomes preoperatively and postoperatively. The MacNab criteria were used to evaluate the satisfaction of patient. The disc height (DH), lumbar lordosis (LL) and segmental lordosis angle (SLA) were measured before and after surgery. We used patient's CT data to establish the finite element model of smile-face surgery and open TLIF, and analyze biomechanical stability of two methods. Results: Smile-face surgery group showed shorter operation time, shorter incision, less blood loss, shorter hospital stay than open TLIF (P < 0.05). The back VAS in smile-face surgery group was significantly lower than that in open TLIF immediately and 3 months after surgery, and no significant difference was observed 1 year, 2 years and 5 years after surgery. There was no significant difference in the leg pain VAS and ODI between both groups after surgery. No significant difference was observed between two groups in the DH, LL and SLA. At 5-year follow-up, grade I or II fusion was achieved in 99.00% (100/101) segments of smile-face surgery group and 97.67% (84/86) segments of open TLIF group according to Bridwell system. The complication rate of open TLIF was higher than that of smile-face surgery (24.32% vs. 0%, P < 0.01). After verification, the established finite element model can accurately simulate the biological structure of lumbar spine and there was no significant difference in biomechanical stability between two methods. Conclusions: Smile-face surgery has some advantages over open TLIF including smaller aggression, less blood loss, and lower cost, indicating that it is a good choice of treatment for multi-segmental LDDs. Both methods can achieve good biomechanical stability.

11.
Nucleic Acids Res ; 2022 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-36401871

RESUMO

Many RNAs fold into multiple structures at equilibrium, and there is a need to sample these structures according to their probabilities in the ensemble. The conventional sampling algorithm suffers from two limitations: (i) the sampling phase is slow due to many repeated calculations; and (ii) the end-to-end runtime scales cubically with the sequence length. These issues make it difficult to be applied to long RNAs, such as the full genomes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To address these problems, we devise a new sampling algorithm, LazySampling, which eliminates redundant work via on-demand caching. Based on LazySampling, we further derive LinearSampling, an end-to-end linear time sampling algorithm. Benchmarking on nine diverse RNA families, the sampled structures from LinearSampling correlate better with the well-established secondary structures than Vienna RNAsubopt and RNAplfold. More importantly, LinearSampling is orders of magnitude faster than standard tools, being 428× faster (72 s versus 8.6 h) than RNAsubopt on the full genome of SARS-CoV-2 (29 903 nt). The resulting sample landscape correlates well with the experimentally guided secondary structure models, and is closer to the alternative conformations revealed by experimentally driven analysis. Finally, LinearSampling finds 23 regions of 15 nt with high accessibilities in the SARS-CoV-2 genome, which are potential targets for COVID-19 diagnostics and therapeutics.

12.
Biochem Genet ; 2022 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-36414922

RESUMO

Codon usage bias of coding sequences has been usually used for exploring the evolutionary factors that affect the variation of genes. We took 20 chloroplast genomes of Malus species into account to explore the codon usage patterns, including the composition, relationship between GC3s and effective number of codons, the parity rule two analyses, the relative synonymous codon usage, the codon adaptation index, the frequency of optimal codons, the codon bias index, etc., of their coding genes. The relationship between GC3 and the ENC values showed that when the separate genes are concerned, the distribution of their GC3 contents is relatively concentrated and the distribution of the ENC values are from 35 to 61 or so. The neutrality plot showed that the correlation coefficient between GC12 and GC3 is 0.095, revealing the mutation factor played a weak role in codon pattern formation. Correspondence analysis results revealed that the codon usage patterns in the chloroplast genomes of Malus species are similar. All these results showed that all Malus chloroplast genomes are AT rich ones, the third bases of the codons are affected by the natural selection pressure, the first two nucleotide base of the codon are affected by mutation pressure. Some genes, such as the rsp7, psbA and ycf2 are of lower codon usage divergences, while the rps12, rps16 and ndhD are of higher codon usage divergences. Codon usage bias exists in the Malus genomes could be used for exploring the evolutionary characteristics in chloroplast genomes and for further study on evolutionary phenomenon in other species.

13.
Psychophysiology ; : e14220, 2022 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-36416584

RESUMO

Fluctuation patterns of physiological response after acute stress might indicate one's coping potential with stress, yet this relationship has not been widely examined. The present study investigated how Locus of Control (LOC) can influence cortisol and HR responses in an uncontrollable stressful situation. Seventy-three participants were exposed to acute stress through the Trier Social Stress Test (TSST) after finishing the LOC measures. Multilevel regression results suggested that a curvilinear function best captured the shape of the cortisol trajectories which was further moderated by the level of internal LOC. Moreover, higher internality was associated with greater cortisol reactivity and faster recovery. Our study reveals the link between internal control and endocrine stress response. Finally, cortisol upregulation was discussed, as well as the internality-related accelerated recovery of cortisol, which may be involved in the effect of motivation arousal for better adaptation.

14.
Crit Rev Food Sci Nutr ; : 1-17, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36382683

RESUMO

Maillard reaction is a non-enzymatic thermal reaction during food processing and storage. It massively contributes to the flavor, color, health benefits and safety of foods and could be briefly segmented into initial, intermediate and final stages with the development of a cascade of chemical reactions. During thermal reaction of food ingredients, sugar, protein and amino acids are usually the main substrates, and polyphenols co-existed in food could also participate in the Maillard reaction as a modulator. Polyphenols including flavan-3-ols, hydroxycinnamic acids, flavonoids, and tannins have shown various effects throughout the process of Maillard reaction, including conjugating amino acids/sugars, trapping α-dicarbonyls, capturing Amadori rearrangement products (ARPs), as well as decreasing acrylamide and 5-hydroxymethylfurfural (5-HMF) levels. These effects significantly influenced the flavor, taste and color of processed foods, and also decreased the hazard products' level. The chemical mechanism of polyphenols-Maillard products involved the scavenging of radicals, as well as nucleophilic addition and substitution reactions. In the present review, we concluded and discussed the interaction of polyphenols and Maillard reaction, and proposed some perspectives for future studies.


HighlightsFood polyphenols regulate Maillard reaction through substrates, initial, intermediate and final stages/products of Maillard reaction.The trapping ability of food polyphenols on α-dicarbonyls relied on the structural properties, and was also affected by reaction conditions such as pH value.Food polyphenols could act as potential inhibitors toward the formation of harmful compounds during advanced and final stages of Maillard reaction.The chemical mechanism of polyphenols-Maillard reaction products involved the scavenging of radicals, as well as nucleophilic addition and substitution.

15.
Cancers (Basel) ; 14(21)2022 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-36358825

RESUMO

Real-world study (RWS) is a method to draw conclusions by collecting and analyzing real-world data under a real clinical background. Compared with traditional randomized controlled trials (RCTs), RWSs are favored by clinicians because of their low cost and good extrapolation. In recent years, RWS has made remarkable achievements in the field of general surgery, especially in the drug treatment of advanced malignant tumors. Therefore, to further understand the main contents of the existing RWS and the application prospect of RWS in the future, this paper systematically reviews the clinical application of RWS in malignant tumors in general surgery in the past three years.

16.
Int J Mol Sci ; 23(21)2022 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-36362266

RESUMO

Bacillus genetics need more versatile promoters for gene circuit engineering. UP elements are widely distributed in noncoding regions and interact with the α-subunit of RNA polymerase (RNAP). They can be applied as a standard element for synthetic biology. Characterization of the binding motif between UP elements and RNAP may assist with rational and effective engineering. In this study, 11 Bacillus constitutive promoters were screened for strength in Bacillus licheniformis. The motif in UP elements from a strong native promoter, PLan, was characterized. The influence of specific sequences on RNAP binding and expression strength was investigated both in vitro and in vivo. It was found that sequences up to 50 base pairs upstream of the consensus motif significantly contributed to α-CTD (the alpha subunit carboxy-terminal domain) association. Meanwhile, two repeats of a proximal subsite were able to more strongly activate the expression (by 8.2-fold) through strengthening interactions between UP elements and RNAP. Based the above molecular basis, a synthetic UP element, UP5-2P, was constructed and applied to nine wild-type promoters. Fluorescence polarization results demonstrated that it had an apparent effect on promoter-α-CTD interactions, and elevated expression strength was observed for all the engineered promoters. The highest improved core promoter, Pacpp, was more strongly activated by 7.4-fold. This work thus develops a novel strategy for Bacillus promoter engineering.


Assuntos
Bacillus , Bacillus/genética , Bacillus/metabolismo , Transcrição Genética , Sequência de Bases , RNA Polimerases Dirigidas por DNA/genética , RNA Polimerases Dirigidas por DNA/metabolismo , Regiões Promotoras Genéticas
17.
Hum Brain Mapp ; 2022 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-36394351

RESUMO

Exploring individual brain atrophy patterns is of great value in precision medicine for Alzheimer's disease (AD) and mild cognitive impairment (MCI). However, the current individual brain atrophy detection models are deficient. Here, we proposed a framework called generative adversarial network constrained multiple loss autoencoder (GANCMLAE) for precisely depicting individual atrophy patterns. The GANCMLAE model was trained using normal controls (NCs) from the Alzheimer's Disease Neuroimaging Initiative cohort, and the Xuanwu cohort was employed to validate the robustness of the model. The potential of the model for identifying different atrophy patterns of MCI subtypes was also assessed. Furthermore, the clinical application potential of the GANCMLAE model was investigated. The results showed that the model can achieve good image reconstruction performance on the structural similarity index measure (0.929 ± 0.003), peak signal-to-noise ratio (31.04 ± 0.09), and mean squared error (0.0014 ± 0.0001) with less latent loss in the Xuanwu cohort. The individual atrophy patterns extracted from this model are more precise in reflecting the clinical symptoms of MCI subtypes. The individual atrophy patterns exhibit a better discriminative power in identifying patients with AD and MCI from NCs than those of the t-test model, with areas under the receiver operating characteristic curve of 0.867 (95%: 0.837-0.897) and 0.752 (95%: 0.71-0.790), respectively. Similar findings are also reported in the AD and MCI subgroups. In conclusion, the GANCMLAE model can serve as an effective tool for individualised atrophy detection.

18.
Chem Asian J ; : e202200993, 2022 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-36323636

RESUMO

Bimetallic nanomaterials exhibit excellent catalytic performance in photothermal CO2 hydrogenation due to the synergistic effect between the two metal components. However, the component-performance relationship remains unclear, which hinders the design of efficient bimetallic catalysts and the investigation of catalytic reaction mechanism. Here we illustrate the influence of the composition of binary alloy on their performance of photothermal catalytic CO2 hydrogenation by using monodispersed Pd-Ni nanocrystal as an example. Our study reveals that Ni and Pd play a significantly different role in the catalytic processes. Higher Ni component in the catalysts could lead to stronger light absorption, higher activity, and lower CO selectivity. The optimized Pd4 Ni1 -SiO2 catalyst exhibited a near-unity and stable CO production rate of 230 mmol ⋅ g-1 ⋅ h-1 under 25-sun illumination. This study paves the way for the usage of bimetal in photothermal CO2 catalysis towards more efficient solar-to-chemical energy conversions, and sheds light on some general design principles of bimetallic catalysts to balance the intrinsic properties of individual components.

19.
Artigo em Inglês | MEDLINE | ID: mdl-36420958

RESUMO

Single crystal surfaces with highly coordinated sites very often hold high specific activities toward oxygen reduction reaction (ORR) and others. Transposing their high specific activity to practical high-surface-area electrocatalysts remains challenging. Here, ultrathin Pt(100) alloy surface is constructed via epitaxial growth. The surface shows 3.1-6.9% compressive strain and bulk-like characteristics as demonstrated by site-probe reactions and different spectroscopies. Its ORR activity exceeds that of bulk Pt3Ni(100) and Pt(111) and presents a 19-fold increase in specific activity and a 13-fold increase in mass activity relative to commercial Pt/C. Moreover, the electrochemically active surface area (ECSA) is increased by 4-fold compared to traditional thin films (e.g. NSTF), which makes the catalyst more tolerant to voltage loss at high current densities under fuel cell operation. This work broadens the family of extended surface catalysts and highlights the knowledge-driven approach in the development of advanced electrocatalysts.

20.
J Acoust Soc Am ; 152(4): 2128, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36319223

RESUMO

In an underwater acoustic direct-sequence code-division multiple-access (DS-CDMA) system, the performance of the conventional receiver is severely limited by the strong multiple-access interferences, which is due to the near-far effect. In this paper, a time-frequency-time with eigendecomposition-based blind beamformer (TFT-EBB) method is proposed for a distant user to suppress strong interference from a nearby user in DS-CDMA underwater acoustic communications. When the interference level is moderately higher than that of the desired signal, the TFT-EBB method can estimate the composite steering vector of all multipath components of the weak desired user signal via the eigendecomposition of the array covariance matrix at each frequency bin. Then the proposed energy detection-based RAKE receiver is cascaded to achieve multipath diversity, in which it requires less prior information compared with the conventional RAKE receiver. The proposed method is evaluated by using both simulated and field experimental data, which verifies its effectiveness.

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