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1.
Nucleic Acids Res ; 2024 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-39494527

RESUMO

Drug resistance is a principal limiting factor in cancer treatment. CTR-DB, the Cancer Treatment Response gene signature DataBase, is the first data resource for clinical transcriptomes with cancer treatment response, and meanwhile supports various data analysis functions, providing insights into the molecular determinants of drug resistance. Here we proposed an upgraded version, CTR-DB 2.0 (http://ctrdb.ncpsb.org.cn). Around 190 up-to-date source datasets with primary resistance information (129% increase compared to version 1.0) and 13 acquired-resistant datasets (a new dataset type), covering 10 856 patient samples (111% increase), 39 cancer types (39% increase) and 346 therapeutic regimens (26% increase), have been collected. In terms of function, for the single dataset analysis and multiple-dataset comparison modules, CTR-DB 2.0 added new gene set enrichment, tumor microenvironment (TME) and signature connectivity analysis functions to help elucidate drug resistance mechanisms and their homogeneity/heterogeneity and discover candidate combinational therapies. Furthermore, biomarker-related functions were greatly extended. CTR-DB 2.0 newly supported the validation of cell types in the TME as predictive biomarkers of treatment response, especially the validation of a combinational biomarker panel and even the direct discovery of the optimal biomarker panel using user-customized CTR-DB patient samples. In addition, the analysis of users' own datasets, application programming interface and data crowdfunding were also added.

2.
Opt Lett ; 49(12): 3504-3507, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38875656

RESUMO

Stable pulse and flat-top frequency comb generation are an indispensable component of many photonic applications, from ranging to communications. Lithium niobate on insulator is an excellent electro-optic (EO) platform, exhibiting high modulation efficiency and low optical loss, making it a fitting candidate for pulse generation through electro-optic modulation of continuous-wave (CW) light, a commonly utilized method for generating ultrashort pulses. Here, we demonstrate an on-chip electro-optic comb generation module on thin-film lithium niobate (TFLN) consisting of a Mach-Zehnder interferometer (MZI) amplitude modulator (AM) and a cascaded phase modulator (PM) system driven by a single-electrode drive. We show that when operated in the correct regime, the lithium niobate chips can generate frequency combs with excellent spectral power flatness. In addition, we optically package one of the pulse generator chips via photonic wire bonding. The pulses generated by the photonic-wire-bonded device are compressed to 840 fs pulse duration using an optical fiber and show extremely stable operation.

3.
BMC Cancer ; 24(1): 1060, 2024 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-39192214

RESUMO

BACKGROUND: It is challenging to improve the effects of chemotherapy and reduce its adverse impact on the ovaries. Our previous study suggested that the combination of galaxamide could enhance the antitumor effect of cisplatin (CIS) in HeLa cell xenograft mice. However, their potential effects on ovarian tissues remain unknown. METHODS: The Hela tumor-bearing female BALB/c mice model was established and randomly divided into three groups: control group (PBS group), CIS group (0.3 mg/kg CIS group) and galaxamide group (0.3 mg/kg CIS + 3 mg/kg galaxamide-treated group). The serum sex hormones levels, ovarian morphology, functional and molecular characterisation were determined and compared with those of the control group. RESULTS: The hormonal effects indicated premature ovarian insufficiency (POI) associated with CIS-induced tumor-bearing mice. CIS induces the apoptosis in primordial and developing follicles and subsequently increases follicular atresia, eventually leading to follicle loss. After cotreatment, galaxamide significantly increased anti-Mullerian hormone (AMH) and follicle-stimulating hormone receptor (FSHR) expression and prevented the CIS-induced PI3K pathway, which triggers follicle activation, apoptosis or atresia. CONCLUSION: These findings demonstrate that galaxamide could attenuate CIS-induced follicle loss by acting on the PI3K signaling pathway by stimulating AMH and/or FSHR and thus provides promising therapeutic options for patients with cervical cancer.


Assuntos
Cisplatino , Fosfatidilinositol 3-Quinases , Insuficiência Ovariana Primária , Transdução de Sinais , Animais , Insuficiência Ovariana Primária/induzido quimicamente , Insuficiência Ovariana Primária/tratamento farmacológico , Insuficiência Ovariana Primária/metabolismo , Feminino , Humanos , Camundongos , Cisplatino/efeitos adversos , Transdução de Sinais/efeitos dos fármacos , Células HeLa , Fosfatidilinositol 3-Quinases/metabolismo , Camundongos Endogâmicos BALB C , Apoptose/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto , Hormônio Antimülleriano/sangue , Hormônio Antimülleriano/metabolismo , Antineoplásicos/farmacologia , Neoplasias do Colo do Útero/tratamento farmacológico , Neoplasias do Colo do Útero/metabolismo , Neoplasias do Colo do Útero/patologia , Receptores do FSH/metabolismo , Receptores do FSH/genética
4.
J Obstet Gynaecol Can ; 46(3): 102266, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37940040

RESUMO

OBJECTIVES: To evaluate the occurrence of retained products of conception (RPOC) after termination of pregnancy in the first trimester and to assess the vascular signals with transvaginal ultrasonography (TVUS) examination in the detection of retained products. METHODS: A retrospective cohort study was performed using TVUS examination in patients following termination of pregnancy. In cases of RPOC, 3 scales of vascular signal were identified: type 1, no or small amount, spot flow signals; type 2, medium amount, strip-like flow signals; type 3, rich amount, circumferential-like flow signals. The correlation between vascular signals and placenta accreta spectrum (PAS) staging was proposed by sonography and histopathology findings. RESULTS: The 3 vascular patterns were differently distributed within non-RPOC as well as RPOC patients with and without PAS: type 1 vascular signal detection rates of non-RPOC and RPOC were 97.8% (262/268) and 28.1% (18/64), respectively. Of 64 cases of RPOC, 48.4% (31/64) of the patients had type 2 vascular signals. Vascular signals were enhanced in RPOC with PAS patients whose diagnosis was confirmed by histopathology. CONCLUSIONS: The vascularity (amount of flow), vascular pattern (spot, strip- or circumferential-like flow), and the flow penetrating myometrium were significant findings for distinguishing concomitant RPOC with and without PAS. Additionally, RPOC may contribute to PAS progression, or PAS and RPOC in coordination strengthen the observed vascular signals.


Assuntos
Aborto Induzido , Aborto Espontâneo , Doenças Placentárias , Placenta Retida , Complicações na Gravidez , Gravidez , Humanos , Feminino , Primeiro Trimestre da Gravidez , Placenta Retida/diagnóstico por imagem , Estudos Retrospectivos
5.
J Am Chem Soc ; 145(28): 15600-15610, 2023 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-37418344

RESUMO

Single-atom catalysts with a well-defined metal center open unique opportunities for exploring the catalytically active site and reaction mechanism of chemical reactions. However, understanding of the electronic and structural dynamics of single-atom catalytic centers under reaction conditions is still limited due to the challenge of combining operando techniques that are sensitive to such sites and model single-atom systems. Herein, supported by state-of-the-art operando techniques, we provide an in-depth study of the dynamic structural and electronic evolution during the electrochemical CO2 reduction reaction (CO2RR) of a model catalyst comprising iron only as a high-spin (HS) Fe(III)N4 center in its resting state. Operando 57Fe Mössbauer and X-ray absorption spectroscopies clearly evidence the change from a HS Fe(III)N4 to a HS Fe(II)N4 center with decreasing potential, CO2- or Ar-saturation of the electrolyte, leading to different adsorbates and stability of the HS Fe(II)N4 center. With operando Raman spectroscopy and cyclic voltammetry, we identify that the phthalocyanine (Pc) ligand coordinating the iron cation center undergoes a redox process from Fe(II)Pc to Fe(II)Pc-. Altogether, the HS Fe(II)Pc- species is identified as the catalytic intermediate for CO2RR. Furthermore, theoretical calculations reveal that the electroreduction of the Pc ligand modifies the d-band center of the in situ generated HS Fe(II)Pc- species, resulting in an optimal binding strength to CO2 and thus boosting the catalytic performance of CO2RR. This work provides both experimental and theoretical evidence toward the electronic structural and dynamics of reactive sites in single-Fe-atom materials and shall guide the design of novel efficient catalysts for CO2RR.

6.
Proc Biol Sci ; 290(1992): 20222014, 2023 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-36722078

RESUMO

The principal animal lineages (phyla) diverged in the Cambrian, but most diversity at lower taxonomic ranks arose more gradually over the subsequent 500 Myr. Annelid worms seem to exemplify this pattern, based on molecular analyses and the fossil record: Cambrian Burgess Shale-type deposits host a single, early-diverging crown-group annelid alongside a morphologically and taxonomically conservative stem group; the polychaete sub-classes diverge in the Ordovician; and many orders and families are first documented in Carboniferous Lagerstätten. Fifteen new fossils of the 'phoronid' Iotuba (=Eophoronis) chengjiangensis from the early Cambrian Chengjiang Lagerstätte challenge this picture. A chaetal cephalic cage surrounds a retractile head with branchial plates, affiliating Iotuba with the derived polychaete families 'Flabelligeridae' and Acrocirridae. Unless this similarity represents profound convergent evolution, this relationship would pull back the origin of the nested crown groups of Cirratuliformia, Sedentaria and Pleistoannelida by tens of millions of years-indicating a dramatic unseen origin of modern annelid diversity in the heat of the Cambrian 'explosion'.


Assuntos
Anelídeos , Poliquetos , Animais , Estro , Fósseis , Temperatura Alta
7.
Cell Commun Signal ; 21(1): 182, 2023 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-37488602

RESUMO

Cell migration is a highly orchestrated process requiring the coordination between the cytoskeleton, cell membrane and extracellular matrix adhesions. Our previous study demonstrated that Hax1 interacts with EB2, a microtubule end-binding protein, and this interaction regulate cell migration in keratinocytes. However, little is known about the underlying regulatory mechanism. Here, we show that Hax1 links dynamic focal adhesions to regulate cell migration via interacting with IQGAP1, a multidomain scaffolding protein, which was identified by affinity purification coupled with LC-MS/MS. Biochemical characterizations revealed that C-terminal region of Hax1 and RGCT domain of IQGAP1 are the most critical binding determinants for its interaction. IQGAP1/Hax1 interaction is essential for cell migration in MCF7 cells. Knockdown of HAX1 not only stabilizes focal adhesions, but also impairs the accumulation of IQGAP in focal adhesions. Further study indicates that this interaction is critical for maintaining efficient focal adhesion turnover. Perturbation of the IQGAP1/Hax1 interaction in vivo using a membrane-permeable TAT-RGCT peptide results in impaired focal adhesion turnover, thus leading to inhibition of directional cell migration. Together, our findings unravel a novel interaction between IQGAP1 and Hax1, suggesting that IQGAP1 association with Hax1 plays a significant role in focal adhesion turnover and directional cell migration. Video Abstract.


Assuntos
Adesões Focais , Espectrometria de Massas em Tandem , Cromatografia Líquida , Membrana Celular
8.
J Org Chem ; 88(12): 7849-7857, 2023 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-36696680

RESUMO

In the presence of chiral pyridoxamine 4b as the catalyst and 2,2-diphenylglycine (3) as the amine source, asymmetric biomimetic transamination of trifluoromethyl ketones produces optically active α-trifluoromethyl amines 6 in 81-98% yields with 88-95% ee's under mild conditions.


Assuntos
Biomimética , Cetonas , Aminação , Aminas , Catálise
9.
Environ Sci Technol ; 57(37): 14071-14081, 2023 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-37681682

RESUMO

Currently, the lack of model catalysts limits the understanding of the catalytic essence. Herein, we report the functional group modification of model single atom catalysts (SACs) with an accurately regulated electronic structure for accelerating the sluggish kinetics of the Fenton-like reaction. The amino-modified cobalt phthalocyanine anchored on graphene (CoPc/G-NH2) shows superior catalytic performance in the peroxymonosulfate (PMS) based Fenton-like reaction with Co mass-normalized pseudo-first-order reaction rate constants (kobs, 0.2935 min-1), which is increased by 4 and 163 times compared to those of CoPc/G (0.0737 min-1) and Co3O4/G (0.0018 min-1). Density functional theory (DFT) calculations demonstrate that the modification of the -NH2 group narrows the gap between the d-band center and the Fermi level of a single Co atom, which strengthens the charge transfer rate at the reaction interface and reduces the free energy barrier for the activation of PMS. Moreover, the scale-up experiment realizes 100% phenol removal at 7200-bed volumes during 240 h continuous operation without obvious decline in catalytic performance. This work provides in-depth insight into the catalytic mechanism of Fenton-like reactions and demonstrates the electronic engineering of SACs as an effective strategy for improving the Fenton-like activity to achieve the goal of practical application.


Assuntos
Eletrônica , Poluentes Ambientais , Catálise , Cobalto
10.
Drug Dev Res ; 84(6): 1114-1126, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37154105

RESUMO

Our previous work reported that galaxamide, a cyclopeptide extracted from the seaweed Galaxaura filamentosa, showed antiproliferative activity against HeLa cells by MTT assay. In this study, the growth-inhibitory effects of galaxamide in HeLa cells and xenograft mouse models were investigated. It was found galaxamide significantly inhibited cell growth, colony formation, migration, and invasion and induced cell apoptosis by inhibiting the Wnt signaling pathway in HeLa cells. RNA sequencing revealed that galaxamide regulated stemness by Wnt6 signaling pathway in HeLa cells. By analyzing The Cancer Genome Atlas database, Wnt6 was found to be negatively/positively correlated with stemness- and apoptosis-related genes in human cervical cancer. Cancer stem-like cells (CSCs) isolated and enriched from HeLa cells demonstrated elevated Wnt6 and ß-catenin genes compared with nonstem HeLa cells. After galaxamide treatment, CSCs showed abrogation of sphere-forming ability, along with inhibition of stemness-related and Wnt pathway genes. Galaxamide treatment was also accompanied by the induction of apoptosis in HeLa cells, which was consistent with the results in BALB/c nude mice. Our results provide evidence that suppression of stemness by downregulating the Wnt signaling pathway is the molecular mechanism by which galaxamide effectively inhibits cell growth and induces apoptosis in cervical cancer cells.


Assuntos
Neoplasias do Colo do Útero , Via de Sinalização Wnt , Feminino , Humanos , Animais , Camundongos , Células HeLa , beta Catenina/genética , Neoplasias do Colo do Útero/genética , Camundongos Nus , Peptídeos Cíclicos/química , Peptídeos Cíclicos/farmacologia , Apoptose , Proliferação de Células , Linhagem Celular Tumoral
11.
Angew Chem Int Ed Engl ; 62(10): e202211174, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36562773

RESUMO

Electrochemically reducing CO2 to valuable fuels or feedstocks is recognized as a promising strategy to simultaneously tackle the crises of fossil fuel shortage and carbon emission. Sn-based catalysts have been widely studied for electrochemical CO2 reduction reaction (CO2 RR) to make formic acid/formate, which unfortunately still suffer from low activity, selectivity and stability. In this work, halogen (F, Cl, Br or I) was introduced into the Sn catalyst by a facile hydrolysis method. The presence of halogen was confirmed by a collection of ex situ and in situ characterizations, which rendered a more positive valence state of Sn in halogen-incorporated Sn catalyst as compared to unmodified Sn under cathodic potentials in CO2 RR and therefore tuned the adsorption strength of the key intermediate (*OCHO) toward formate formation. As a result, the halogen-incorporated Sn catalyst exhibited greatly enhanced catalytic performance in electrochemical CO2 RR to produce formate.

12.
Opt Lett ; 47(20): 5309-5312, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-36240349

RESUMO

In this Letter, we report a scheme that combines time-of-flight (ToF) ranging detection of multi-repetition-rate pulses with asymmetric dual-comb ranging (DCR) measurement. Notably, this combination extends the non-ambiguity range (NAR) of the DCR method without sacrificing its refresh rate and distance precision. With this scheme, we demonstrate absolute distance measurement of moving targets with an NAR of 1.5 km, which is 5× larger than that allowed solely by the DCR method for a given refresh rate at 500 kHz. The ranging precision in a single measurement of 2 µs reaches 10 µm at an effective distance of 571 m (down to 60 nm in 0.1 s). This combined scheme benefits remote sensing of high-speed objects.


Assuntos
Frequência Cardíaca
13.
J Acoust Soc Am ; 151(4): 2613, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35461480

RESUMO

Geoacoustic inversion using moving sensors attracts lots of interest due to the ease of deployment and low cost. However, the well-established techniques, such as matched-field inversion (MFI), may run into difficulties when the sensors are in a range-dependent environment for mismatch issues and increasing unknown parameters. Given a range-dependent environment, the paper focuses on the inversion using a synthetic aperture created by moving sensors in the presence of the Doppler effect. The derivation is given to obtain an equivalent range-independent environmental model for fast inversion, instead of a range-dependent one. The received fields are modified using the Doppler-shifted wavenumbers. The simulations and results of the SWellEx-96 experimental data verify the effectiveness of the proposed inversion method.

14.
Angew Chem Int Ed Engl ; 61(29): e202204156, 2022 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-35524419

RESUMO

A Pd-catalyzed asymmetric double hydroxycarbonylation of terminal alkynes was developed by using relay catalysis, providing a highly efficient route to chiral succinic acids (41 examples, 76-94 %, 94-99 % ee). Key to success was the combinatorial use of a Pd precursor with two distinct phosphine ligands in one pot. The synthetic utilities of this protocol were showcased in the facile synthesis of key intermediates for chiral pharmaceuticals.


Assuntos
Alcinos , Paládio , Catálise , Estrutura Molecular , Estereoisomerismo , Succinatos
15.
Appl Environ Microbiol ; 87(23): e0155621, 2021 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-34756060

RESUMO

Magnetotactic bacteria (MTB) are prokaryotes that form intracellular magnetite (Fe3O4) or greigite (Fe3S4) nanocrystals with tailored sizes, often in chain configurations. Such magnetic particles are each surrounded by a lipid bilayer membrane, called a magnetosome, and provide a model system for studying the formation and function of specialized internal structures in prokaryotes. Using fluorescence-coupled scanning electron microscopy, we identified a novel magnetotactic spirillum, XQGS-1, from freshwater Xingqinggong Lake, Xi'an City, Shaanxi Province, China. Phylogenetic analyses based on 16S rRNA gene sequences indicate that strain XQGS-1 represents a novel genus of the Alphaproteobacteria class in the Proteobacteria phylum. Transmission electron microscopy analyses reveal that strain XQGS-1 forms on average 17 ± 3 magnetite magnetosome particles with an ideal truncated octahedral morphology, with an average length and width of 88.3 ± 11.7 nm and 83.3 ± 11.0 nm, respectively. They are tightly organized into a single chain along the cell long axis close to the concave side of the cell. Intrachain magnetic interactions likely result in these large equidimensional magnetite crystals behaving as magnetically stable single-domain particles that enable bacterial magnetotaxis. Combined structural and chemical analyses demonstrate that XQGS-1 cells also biomineralize intracellular amorphous calcium phosphate (2 to 3 granules per cell; 90.5- ± 19.3-nm average size) and weakly crystalline calcium carbonate (2 to 3 granules per cell; 100.4- ± 21.4-nm average size) in addition to magnetite. Our results expand the taxonomic diversity of MTB and provide evidence for intracellular calcium phosphate biomineralization in MTB. IMPORTANCE Biomineralization is a widespread process in eukaryotes that form shells, teeth, or bones. It also occurs commonly in prokaryotes, resulting in more than 60 known minerals formed by different bacteria under wide-ranging conditions. Among them, magnetotactic bacteria (MTB) are remarkable because they might represent the earliest organisms that biomineralize intracellular magnetic iron minerals (i.e., magnetite [Fe3O4] or greigite [Fe3S4]). Here, we report a novel magnetotactic spirillum (XQGS-1) that is phylogenetically affiliated with the Alphaproteobacteria class. In addition to magnetite crystals, XQGS-1 cells form intracellular submicrometer calcium carbonate and calcium phosphate granules. This finding supports the view that MTB are also an important microbial group for intracellular calcium carbonate and calcium phosphate biomineralization.


Assuntos
Alphaproteobacteria/classificação , Cálcio , Óxido Ferroso-Férrico , Lagos/microbiologia , Filogenia , Alphaproteobacteria/isolamento & purificação , Carbonato de Cálcio , Fosfatos de Cálcio , China , RNA Ribossômico 16S/genética
16.
Angew Chem Int Ed Engl ; 60(32): 17693-17700, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34109712

RESUMO

As a fundamental type of carbonylation reaction, the alkoxy- and hydroxy-carbonylation of unsaturated hydrocarbons constitutes one of the most important industrial applications of homogeneous catalysis. However, owing to the difficulties in controlling multi-selectivities for asymmetric hydrocarbonylation of alkenes, this reaction is typically limited to vinylarenes and analogues. In this work, a highly efficient asymmetric alkoxy- and hydroxy-carbonylation of ß-carbonyl functionalized alkenes was developed, providing practical and easy access to various densely functionalized chiral molecules with high optical purity from broadly available alkenes, CO, and nucleophiles (>90 examples, 84-99 % ee). This protocol features mild reaction conditions and a broad substrate scope, and the products can be readily transformed into a diverse array of chiral heterocycles. Control experiments revealed the key role of the ß-carbonyl group in determining the enantioselectivity and promoting the activity, which facilitates chiral induction by coordination to the transition metal as rationalized by DFT calculations. The strategy of utilizing an innate functional group as the directing group on the alkene substrate might find further applications in catalytic asymmetric hydrocarbonylation reactions.

17.
Opt Lett ; 45(3): 776-779, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32004309

RESUMO

In this Letter, we utilize an acoustic-optic frequency shifter in a feedforward manner for automatic interpolation of dual-comb spectroscopy, where frequency tuning can be achieved at 5.45 THz/s with the step size precisely locked to the line spacing (54.5 MHz) of a referenced optical comb without complicated electronics or control programs. Our dual-comb spectrometer involves two near-infrared electro-optic combs at 25 GHz line spacings, nonlinearly converted into the mid-infrared region, revealing fundamental absorption lines of methane gas at 54.5 MHz resolution within a spectral range from 88.04 to 89.04 THz. The method and the system may be useful in many applications, including gas sensing.

18.
Orthod Craniofac Res ; 23(4): 509-516, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32583548

RESUMO

OBJECTIVE: Appropriate torque expression contributes to ideal treatment outcomes both clinically and aesthetically. Whether active and passive self-ligating brackets (SLBs) have different torque-control capability in vivo has never been reported. The purpose of present study was to explore whether there was difference in torque expression in active and passive SLBs. SETTING AND SAMPLE POPULATION: In this retrospective study, 225 patients with four first premolar extractions were enrolled. For each patient, the digital lateral cephalometric radiographs were taken before and after treatment. MATERIALS AND METHODS: The study consisted of 2 groups: 111 subjects were treated with passive SLBs (Damon Q, Ormco) and 114 subjects with active SLBs (Empower 2, American Orthodontics). Measurements to determine skeletal changes and incisor inclination were obtained from cephalometric tracings using Dolphin software (version 11.8, USA). Comparisons in both groups and intergroups were compared using t tests and chi-square test. RESULTS: Significant differences in the variation of U1-SN(°), U1-NA(°), L1-NB(°) and L1-FH(°) were found between two groups. More labially inclined maxillary incisors were found in active SLB group, while more labially inclined mandibular incisors were observed in passive SLB group. CONCLUSIONS: With the present prescription set in the two brackets, active SLBs achieved more proclined maxillary incisors and retroclined mandibular incisors. Clinicians should take torque expression of brackets into consideration during orthodontic treatment.


Assuntos
Desenho de Aparelho Ortodôntico , Braquetes Ortodônticos , Dente Pré-Molar , Humanos , Fios Ortodônticos , Estudos Retrospectivos , Torque
19.
Angew Chem Int Ed Engl ; 59(2): 798-803, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31657106

RESUMO

Designing effective electrocatalysts for the carbon dioxide reduction reaction (CO2 RR) is an appealing approach to tackling the challenges posed by rising CO2 levels and realizing a closed carbon cycle. However, fundamental understanding of the complicated CO2 RR mechanism in CO2 electrocatalysis is still lacking because model systems are limited. We have designed a model nickel single-atom catalyst (Ni SAC) with a uniform structure and well-defined Ni-N4 moiety on a conductive carbon support with which to explore the electrochemical CO2 RR. Operando X-ray absorption near-edge structure spectroscopy, Raman spectroscopy, and near-ambient X-ray photoelectron spectroscopy, revealed that Ni+ in the Ni SAC was highly active for CO2 activation, and functioned as an authentic catalytically active site for the CO2 RR. Furthermore, through combination with a kinetics study, the rate-determining step of the CO2 RR was determined to be *CO2 - +H+ →*COOH. This study tackles the four challenges faced by the CO2 RR; namely, activity, selectivity, stability, and dynamics.

20.
Opt Express ; 27(3): 2747-2753, 2019 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-30732307

RESUMO

In this paper, we experimentally investigate a rich set of Q-switching bunches in the build-up of stretched-pulse mode-locking of an erbium-doped fiber laser. Interestingly, regular clustering of periodic Q-switched mode-locking states is observed in the self-starting process. Moreover, with time-stretch spectroscopy, we record periodic pulse-to-pulse spectral evolution occurring in these turbulent and rapidly-evolving pre-mode-locking states.

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