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1.
Small ; : e2200713, 2022 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-35560983

RESUMO

Owing to the interacted anion and cation redox dynamics in Li2 MnO3 , the high energy density can be obtained for lithium-rich manganese-based layered transition metal (TM) oxide [Li1.2 Ni0.2 Mn0.6 O2 , LNMO]. However, irreversible migration of Mn ions and oxygen release during highly de-lithiation can destroy its layered structure, leading to voltage and capacity decline. Herein, non-TM antimony (Sb) is pinned to the TM layer of LNMO by a facile sol-gel method. High-resolution ex and in situ characterization technologies manifest that the introduction of trace Sb inhibits the migration of Mn ions, forming a more stable structure. Sb can impressively adjust the Mn-O interaction between anions and cations, beneficial to decrease the energy level of Mn 3d and O 2p orbitals and expand their band gap according to the  theoretical calculation results. As a result, the discharge specific capacity and the energy density for SbLi1.2 [Ni0.2 Mn0.6 ]O2 (SLNMO) reaches as high as 301 mAh g-1 and 1019.6 Wh kg-1 at 0.1 C, respectively. Moreover, the voltage decay is reduced by 419.8 mV compared with LNMO. The regulative interaction between Mn 3d and isolated O 2p bands provides an accurate guidance for solving electrochemical performance deficiencies of lithium-rich manganese-based cathode oxide.

2.
Nanoscale ; 2022 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-35543282

RESUMO

Although the application of nanoscale artificial enzymes in various industries is an attractive way to circumvent the intrinsic drawbacks of natural enzymes, their catalytic constant (Kcat) as a critical reaction parameter is far from satisfactory. Presented here is the rational design and fabrication of a unique peroxidase mimic catalyst based upon Pd@PtxRu4-x (1 ≤ x ≤ 3) prepared by coating PtRu alloy as conformal, ultrathin shells on Pd nanocrystals. Benefiting from an optimal Pt/Ru ratio and well-defined {100} facets, together with confining the Pt-Ru alloy to a shell of averagely 3.3-atomic-layer thick (i.e. Pd@Pt-Ru3.3L), the nanocrystals exhibit the highest catalytic activity and kinetics (1.2 × 106 s-1), resulting in a significant increase of catalytic activity compared with the classical PtRu nanozyme (3.6 × 103 s-1) and horseradish peroxidase (4.0 × 103 s-1), respectively. The following density functional theory calculations demonstrate that the origin of the superior catalytic performance could be attributed to the modulation of the adsorption behavior of the key reaction intermediates on the surface. As a proof of concept, its peroxidase mimicking ability is adopted for sensing glucose and glutathione molecules in human serum, with a long linear range and high selectivity. This work opens new horizons for the future development of advanced catalysts based upon alloy nanocrystals for various applications.

3.
Medicine (Baltimore) ; 101(10): e29026, 2022 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-35451405

RESUMO

ABSTRACT: Among the diverse medical education systems in China, the 8-year program is dedicated to cultivating physician scientists. Although the research ability of senior students in 8-year medical programs is a pivotal quality, it remains unclear. This study aimed to clarify the current status and challenges of students' research experience, abilities, and outputs.A multicenter cross-sectional study was conducted in 5 medical schools in northern China. Electronic questionnaires were sent to 235 randomly chosen fifth-grade or sixth-grade 8-year-program medical students. A total of 211 responses were collected and analyzed using SPSS 22.0.Only 13.3% of participants chose research as their future career goal. Students generally felt that conducting research was stressful and difficult. The greatest obstacle was a lack of time due to heavy workloads. The 2 major motivations for research were graduation and/or future employment (75.8%) and research interest (24.2%). More than half of the students (142, 67.3%) had research experience by the time of the survey, among whom 84 students already had research outputs. A higher proportion of students with outputs was motivated by the requirements for graduation or employment compared to students without outputs (71.4% vs 55.2%, P  =  .046).Senior 8-year-program medical students in China generally had high pressure to conduct research and devoted their efforts to overcome these challenges. More guidance and novel encouragement to enhance students' initiative and interest in research could be provided by medical schools and educators in the future.


Assuntos
Estudantes de Medicina , Escolha da Profissão , China , Estudos Transversais , Humanos , Inquéritos e Questionários
4.
Pharmacol Res ; 178: 106155, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35248699

RESUMO

The XELOX chemotherapy protocol that includes capecitabine and oxaliplatin is the routine treatment for colorectal cancer (CRC), but it can cause chemotherapy-related adverse events such as thrombocytopenia (TCP). To identify predictive biomarkers and clarify the mechanism of TCP susceptibility, we conducted integrative analysis using normal colorectal tissue (CRT), plasma, and urine samples collected before CRC patients received adjuvant XELOX chemotherapy. RNA-sequencing and DNA methylation arrays were performed on CRT samples, while liquid chromatography-mass spectrometry was performed on CRT, plasma, and urine samples. Differentially expressed features (DEFs) from each uni-omics analysis were then subjected to integrative analysis using Multi-Omics Factor Analysis (MOFA). Choline-deficiency in plasma and CRT was found as the most critical TCP-related feature. Based on bioinformatic analysis and literature research, we further concluded that choline-deficiency was the possible reason for most of the other TCP-related multi-omics DEFs, including metabolites representing reduced sphingolipid de novo synthesis and elevated solute carrier-mediated transmembrane transportation in CRT and plasma, DNA hypermethylation and elevated expression of genes involved in neuronal system genes. In terms of thrombocytopoiesis, these TCP-related DEFs may cause atypical maintenance and differentiation of megakaryocyte, resulting a suppressed ability of thrombocytopoiesis, making patients more susceptible to chemotherapy-induced TCP. At last, prediction models were developed and validated with reasonably good discrimination. The area under curves (AUCs) of training sets were all > 0.9, while validation sets had AUCs between 0.778 and 0.926. In conclusion, our results produced reliable marker systems for predicting TCP and promising target for developing precision treatment to prevent TCP.


Assuntos
Antineoplásicos , Deficiência de Colina , Neoplasias Colorretais , Leucopenia , Trombocitopenia , Antineoplásicos/efeitos adversos , Colina , Deficiência de Colina/induzido quimicamente , Deficiência de Colina/tratamento farmacológico , Neoplasias Colorretais/induzido quimicamente , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Fluoruracila/uso terapêutico , Humanos , Leucopenia/induzido quimicamente , Trombocitopenia/induzido quimicamente
5.
Biomacromolecules ; 23(5): 1938-1948, 2022 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-35226471

RESUMO

Bamboo fibers and parenchyma cells, the two dominant types of cells in bamboo, exhibit some interesting differences in cellulose crystalline structures. In the present investigation, we further demonstrated that these structural differences affect their response during ionic liquid (IL) pretreatment and the sugar conversion yield, by tracking their changes in morphology, chemical, and crystalline structures. All of the results pointed to the fact that the cellulose from bamboo fibers exhibited higher recalcitrance to IL pretreatment, with a significantly lower change in crystallinity index, d spacings from the (110) and (11̅0) planes, crystallite sizes, and easier transformation from cellulose I to cellulose II after pretreatment, as compared to that from parenchyma cells. Furthermore, the crystalline parameters of (110) and (11̅0) lattice planes exhibited more changes compared to the (200) direction. This investigation highlights the significance of parenchyma cell wastes from bamboo processing plants as a competitive candidate for the biorefinery industry.


Assuntos
Celulose , Líquidos Iônicos , Carboidratos , Celulose/química , Hidrólise , Líquidos Iônicos/química
6.
Int J Mol Sci ; 23(3)2022 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-35163516

RESUMO

Members of the Mi14-3-3 gene family interact with target proteins that are widely involved in plant hormone signal transduction and physiology-related metabolism and play important roles in plant growth, development and stress responses. In this study, 14-3-3s family members are identified by the bioinformatic analysis of the mango (Mangifera indica L.) genome. The gene structures, chromosomal distributions, genetic evolution, and expression patterns of these genes and the physical and chemical properties and conserved motifs of their proteins are analysed systematically. The results identified 16 members of the 14-3-3 genes family in the mango genome. The members were not evenly distributed across the chromosomes, and the gene structure analysis showed that the gene sequence length and intron number varied greatly among the different members. Protein sequence analysis showed that the Mi14-3-3 proteins had similar physical and chemical properties and secondary and tertiary structures, and protein subcellular localization showed that the Mi14-3-3 family proteins were localized to the nucleus. The sequence analysis of the Mi14-3-3s showed that all Mi14-3-3 proteins contain a typical conserved PFAM00244 domain, and promoter sequence analysis showed that the Mi14-3-3 promoters contain multiple hormone-, stress-, and light-responsive cis-regulatory elements. Expression analysis showed that the 14-3-3 genes were expressed in all tissues of mango, but that their expression patterns were different. Drought, salt and low temperature stresses affected the expression levels of 14-3-3 genes, and different 14-3-3 genes had different responses to these stresses. This study provides a reference for further studies on the function and regulation of Mi14-3-3 family members.


Assuntos
Proteínas 14-3-3/química , Proteínas 14-3-3/genética , Perfilação da Expressão Gênica/métodos , Mangifera/crescimento & desenvolvimento , Sequência de Aminoácidos , Mapeamento Cromossômico , Evolução Molecular , Regulação da Expressão Gênica de Plantas , Mangifera/genética , Família Multigênica , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Regiões Promotoras Genéticas , Domínios Proteicos , Estrutura Terciária de Proteína , Estresse Fisiológico
7.
Mol Ther Nucleic Acids ; 27: 227-240, 2022 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-34976440

RESUMO

Metastasis is the main cause of cervical cancer lethality, but to date, no effective treatment has been developed to block metastasis. Circular RNAs (circRNAs) were recently found to be involved in cancer metastasis. In this study, we identified a downregulated circRNA derived from the host gene Gli1 (hsa_circ_0005358) in cervical cancer tissues, which was expressed at lower levels in tissues with extracervical metastasis than in those without extracervical metastasis. Upregulation of hsa_circ_0005358 significantly suppressed the migration and invasion of cervical cancer cells in vitro, and downregulation of hsa_circ_0005358 had the opposite effect. A mouse model revealed that cervical cancer cells overexpressing hsa_circ_0005358 possessed weaker metastatic potential in vivo. RNA-pull-down assay, mass spectrometry, and RNA immunoprecipitation validated the findings that hsa_circ_0005358 functions via its 215-224 sequence, which interacts with polypyrimidine tract-binding protein 1 (PTBP1). RNA-sequencing profiling revealed that CUB-domain-containing protein 1 (CDCP1) is a common target for hsa_circ_0005358 and PTBP1. We further confirmed that hsa_circ_0005358 sequestered PTBP1, preventing it from stabilizing CDCP1 mRNA, reducing CDCP1 protein translation and ultimately suppressing cancer metastasis. Our findings reveal the function of hsa_circ_0005358 in tumor metastasis, which may be applied to a potential therapeutic approach for patients with metastatic cervical cancer.

8.
Acta Biomater ; 137: 252-261, 2022 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-34653696

RESUMO

The Ca2+ buffering capacity of mitochondria maintains the balance of cell physiological activities. The exogenous reactive oxygen species (ROS) can be used to break the balance, resulting in mitochondrial dysfunction and irreversible cell apoptosis. Herein, the CaCO3-based tumor microenvironment (TME) responsive nanoplatform (CaNPCAT+BSO@Ce6-PEG) was designed for oxygen/GSH depletion-boosted photodynamic therapy (PDT) and mitochondrial Ca2+-overloading synergistic therapy. In acidic TME, CaCO3 decomposed and released the cargos (catalase (CAT), buthionine sulfoximine (BSO), chlorin e6 (Ce6), and Ca2+). The tumor hypoxia and reductive microenvironment could be significantly reversed by CAT and BSO, which greatly enhanced the PDT efficacy. The generated 1O2 during PDT process not only directly killed cancer cells but also destroyed the Ca2+ buffering capacity, leading to the mitochondrial Ca2+-overloading. The increased Ca2+ concentration promoted the process of oxidative phosphorylation and inhibited the production of adenosine triphosphate (ATP), resulting in the acceleration of cell death. Under the joint action of enhanced PDT and mitochondrial Ca2+-overloading, the CaNPCAT+BSO@Ce6-PEG NPs showed remarkable synergistic effects in tumor inhibition without any side effects. STATEMENT OF SIGNIFICANCE: In the manuscript, a CaCO3-based nano-platform for tumor microenvironment response was designed. With the decomposition of CaNPCAT+BSO@Ce6-PEG NPs in the acidic tumor microenvironment, the released catalase (CAT) and buthionine sulfoximine (BSO) could relieve the tumor hypoxia and inhibit GSH production. Under 660 nm laser irradiation, the photodynamic effect was enhanced and caused apoptosis. Meanwhile, the Ca2+ buffering capacity was destroyed which led to the mitochondrial Ca2+-overloading. The synergistic effect of enhanced PDT and mitochondrial Ca2+-overloading made the CaNPCAT+BSO@Ce6-PEG NPs present remarkable antitumor performance.


Assuntos
Nanopartículas , Neoplasias , Fotoquimioterapia , Porfirinas , Linhagem Celular Tumoral , Glutationa/farmacologia , Humanos , Mitocôndrias , Neoplasias/tratamento farmacológico , Oxigênio/farmacologia , Fármacos Fotossensibilizantes/farmacologia , Porfirinas/farmacologia , Microambiente Tumoral
9.
Angew Chem Int Ed Engl ; 61(3): e202111670, 2022 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-34668284

RESUMO

We report an effective strategy to enhance CO2 electroreduction (CER) properties of Cu-based Ruddlesden-Popper (RP) perovskite oxides by engineering their A-site cation deficiencies. With La2-x CuO4-δ (L2-x C, x=0, 0.1, 0.2, and 0.3) as proof-of-concept catalysts, we demonstrate that their CER activity and selectivity (to C2+ or CH4 ) show either a volcano-type or an inverted volcano-type dependence on the x values, with the extreme point at x=0.1. Among them, at -1.4 V, the L1.9 C delivers the optimal activity (51.3 mA cm-2 ) and selectivity (41.5 %) for C2+ , comparable to or better than those of most reported Cu-based oxides, while the L1.7 C exhibits the best activity (25.1 mA cm-2 ) and selectivity (22.1 %) for CH4 . Such optimized CER properties could be ascribed to the favorable merits brought by the cation-deficiency-induced oxygen vacancies and/or CuO/RP hybrids, including the facilitated adsorption/activation of key reaction species and thus the manipulated reaction pathways.

10.
Food Chem ; 373(Pt B): 131647, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-34838402

RESUMO

An "off-on" fluorescent probe, Nap-DNB, which is based on naphthimide, was designed and developed for the detection of biological selenols in vitro. We have adopted a combination of a low-pH detection environment and reaction sites that are more difficult to destroy to avoid the interference of a large number of biological thiols in biological samples. Nap-DNB can completely respond to selenocysteine within 15 mins, with a detection limit of 92 nM. Nap-DNB was successfully used for the detection of selenols in the serum, liver, and longissimus dorsi of selenium-enriched Tan sheep. Through comparison, we found that the detection of selenols by the Nap-DNB is similar to that by thioredoxin reductase and glutathione peroxidase in a commercial kit method. Nap-DNB can be used for the detection of selenols in selenium-enriched Tan sheep.


Assuntos
Compostos de Selênio , Selênio , Animais , Corantes Fluorescentes , Glutationa Peroxidase , Selenocisteína , Ovinos , Tiorredoxina Dissulfeto Redutase
11.
Adv Sci (Weinh) ; 9(3): e2103567, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34766738

RESUMO

Hitherto, there are almost no reports on the complete reconstruction in hydrogen evolution reaction (HER). Herein, the authors develop a new type of reconfigurable fluoride (such as CoF2 ) pre-catalysts, with ultra-fast and in-depth self-reconstruction, substantially promoting HER activity. By experiments and density functional theory (DFT) calculations, the unique surface structure of fluorides, alkaline electrolyte and bias voltage are identified as key factors for complete reconstruction during HER. The enrichment of F atoms on surface of fluorides provides the feasibility of spontaneous and continuous reconstruction. The alkaline electrolyte triggers rapid F- leaching and supplies an immediate complement of OH- to form amorphous α-Co(OH)2 which rapidly transforms into ß-Co(OH)2 . The bias voltage promotes amorphous crystallization and accelerates the reconstruction process. These endow the generation of mono-component and crystalline ß-Co(OH)2 with a loose and defective structure, leading to an ultra-low overpotential of 54 mV at 10 mA cm-2 and super long-term stability exceeding that of Pt/C. Moreover, DFT calculations confirm that F- leaching optimizes hydrogen and water adsorption energies, boosting HER kinetics. Impressively, the self-reconstruction is also applicable to other non-noble transition metal fluorides. The work builds the fundamental comprehension of complete self-reconstruction during HER and provides a new perspective to conceive advanced catalysts.

12.
Anal Chem ; 94(2): 1126-1134, 2022 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-34935356

RESUMO

Semicarbazide (SEM) is a widespread carcinogenic and neurotoxic food contaminant, originating from the metabolite of antibiotic nitrofurazone, which is used in aquaculture, or thermal decomposition byproduct of a flour blowing agent azodicarbonamide. Although optical detection technologies are powerful tools considering the advantages of fast response and visualization detection, there are few optical nanosensors for highly sensitive and visual assays of SEM due to no luminescence response and UV absorbance of SEM. Herein, an upconversion luminescence (UCL)-based nanosensor was designed for visual detection of SEM with high sensitivity and good selectivity. The nanosensor was constructed by combining upconversion nanoparticles (UCNPs) and phosphomolybdic acid (PMA), which was used as the specific recognition element of SEM. The developed nanosensor exhibited selective absorbance enhancement and UCL quenching behavior with the addition of SEM based on the inner filter effect (IFE). Since the change in absorbance translated into an exponential change in the luminescence, the sensitivity of the nanosensor was greatly improved. The nanosensor realized a highly sensitive and visual response to SEM in the linear range of 0.5-16 µM with a low limit of detection of 58 nM. Moreover, satisfactory recovery values ranging from 90 to 112% in spiked real samples indicated the practical applicability of the nanosensor. The nanosensor designed here provides a sensitive and convenient sensing strategy for visual detection of hazardous substances and is expected to develop the upconversion sensing application in food safety.


Assuntos
Luminescência , Nanopartículas , Excipientes , Semicarbazidas
13.
ChemSusChem ; : e202102444, 2021 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-34918485

RESUMO

Currently, low intimacy between hydrogenation sites and acidic sites causes unsatisfactory catalytic activity and selectivity for the synthesis of 2,5-hexanedione from C6 furan aldehydes (5-methylfurfural, 5-hydroxymethylfurfural). Herein, iodine(I) modification of Pd-supported catalysts (such as PdI/Al2 O3 and PdI/SiO2 ) was investigated to modulate the hydrogenation sites and acidic sites. Unlike Pd catalysts that produced 71.4 % yield of 2-hydroxymethyl-5-methyl tetrahydrofuran via an overhydrogenation route of 5-methylfurfural, PdI catalysts showed a high efficiency for 2,5-hexanedione with 93.7 % yield by a hydrogenative ring-opening route. More importantly, the selective synthesis of 2,5-hexanedione from 5-hydroxymethylfurfural with a high yield of 50.2 % by the hydrogenolysis and subsequent ring-opening route was reported for the first time. I-modified Pd nanoparticles produced in-situ hydrogen spillover, which promoted the selective C=O hydrogenation and ring-opening steps by regulating the adsorption configuration of the reactants and the transformation of Lewis to Brønsted acidity, respectively.

14.
Anal Chem ; 93(43): 14506-14513, 2021 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-34609831

RESUMO

The components in the exhaled breath have been confirmed to be related to certain diseases, especially studies have shown that isopropanol (IPA) might be closely associated with illnesses such as lung cancer, and are considered as a biomarker. Herein, we designed a portable smartphone platform based on a chemically synthesized ratiometric fluorescent probe for real-time/on-site, sensitive, and quantitative visual detection of IPA in exhaled breath. The fluorescent probe was fabricated by a nicotinamide adenine dinucleotide (NAD+) functional modified onto fluorescent internal standard red carbon dots (RCDs). Whereas, IPA can convert NAD+ into reduced nicotinamide adenine dinucleotide (NADH) through an enzymatic reaction of secondary alcohol dehydrogenase (S-ADH). The electron transfer from IPA to NAD+ emitted a blue emission of NADH, which displayed consecutive color changes from red to light blue. Under optimum conditions, the fluorescent probe shows sensitive responses to IPA with a detection limit as low as 4.45 nM. Moreover, combined with the smartphone color recognizer application (APP), the ratio of fluorescence intensity response was recorded on a blue channel (B)/red channel (R), which has been employed for the visual quantitative determination of IPA with a detection limit of 8.34 nM and a recovery rate of 90.65-110.09% (RSD ≤ 4.83). The method reported here provides a convenient pathway for real-time/on-site and visual detection of IPA in exhaled air and is expected to extend the application of investigation of potential volatile biomarkers for preliminary monitoring and clinical diagnosis.


Assuntos
2-Propanol , Técnicas Biossensoriais , Expiração , Corantes Fluorescentes , Smartphone
15.
Small ; 17(51): e2104241, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34713571

RESUMO

In this study, PtCu-Mo2 C heterostructure with charge redistribution is investigated via first-principles theoretical calculations. Mo2 C can promote the formation of the electron-rich region of PtCu as an active site, displaying an optimized adsorption behavior toward hydrogen in terms of reduced thermodynamic energy barriers. Owing to the attractive density functional theory calculation results, the PtCu-Mo2 C heterostructure is fabricated via carbonization of the unique metal-organic framework (MOF) followed by the replacement reduction reaction for the first time. Owing to its swift kinetics and outstanding specific activity, it exhibits high hydrogen evolution reaction (HER) catalytic activity (26 mV @ 10 mA cm-2 ) and superior mass activity (1 A mgPt -1 at -0.04 V) in acidic media, which is approximately six times that of commercial Pt/C catalysts. The perception of the intrinsic activity origin of the alloy with an excellent structural support can guide the development of Pt-based and other alloy catalysts in future.

16.
Adv Sci (Weinh) ; 8(23): e2102209, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34687174

RESUMO

The highly efficient energy conversion of the polymer-electrolyte-membrane fuel cell (PEMFC) is extremely limited by the sluggish oxygen reduction reaction (ORR) kinetics and poor electrochemical stability of catalysts. Hitherto, to replace costly Pt-based catalysts, non-noble-metal ORR catalysts are developed, among which transition metal-heteroatoms-carbon (TM-H-C) materials present great potential for industrial applications due to their outstanding catalytic activity and low expense. However, their poor stability during testing in a two-electrode system and their high complexity have become a big barrier for commercial applications. Thus, herein, to simplify the research, the typical Fe-N-C material with the relatively simple constitution and structure, is selected as a model catalyst for TM-H-C to explore and improve the stability of such a kind of catalysts. Then, different types of active sites (centers) and coordination in Fe-N-C are systematically summarized and discussed, and the possible attenuation mechanism and strategies are analyzed. Finally, some challenges faced by such catalysts and their prospects are proposed to shed some light on the future development trend of TM-H-C materials for advanced ORR catalysis.

17.
Carbohydr Polym ; 274: 118653, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34702472

RESUMO

To better understand the high recalcitrance of bamboo during bioconversion, the fine spatial distribution of polymers in bamboo was studied with Imaging FTIR microscopy under both transmission and ATR modes, combined with PCA data processing. The results demonstrated that lignin, xylan and hydroxycinnamic acid (HCA) were more concentrated in the fibers near the xylem conduit, while cellulose was evenly distributed across the whole fiber sheath. PCA processing produced a clear separation between bamboo fibers and parenchyma cells, indicating that the parenchyma cells contains more pectin and HCA than fibers. It also demonstrated that cellulose, xylan and S-lignin were concentrated most heavily in bamboo fiber secondary cell walls, while G-lignin, pectin and HCA were found more in the compound middle lamella. The revealed information regarding polymer distribution is of great significance for better understanding of the inherent design mechanism of plant cell wall and its efficient utilization.

18.
Front Oncol ; 11: 744871, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34589438

RESUMO

OBJECTIVE: The role of salvage radiotherapy (RT) in the treatment for vaginal recurrence of cervical cancer in patients after prior surgery remains controversial. The aim of this study was to evaluate the efficacy and toxicity of salvage RT and explore prognostic factors associated with the survival after recurrence. METHODS: Patients with cervical cancer, treated for vaginal recurrences at Peking Union Medical College Hospital between July 2011 and November 2019, were identified. All the patients underwent prior surgery for primary tumor and received salvage RT including external beam radiotherapy (EBRT), brachytherapy (BT), or both. The irradiation field and dose depended on the conditions of patients. Recurrence patterns were classified into four categories according to the site of recurrence. Prognostic factors on the overall survival (OS), progression-free survival (PFS), and local control (LC) were analyzed, and late toxicity was evaluated. RESULTS: A total of 141 patients were included in the analysis, with a median follow-up time of 40.8 months. The estimated 5-year OS, PFS, and LC rates were 81%, 75%, and 87%, respectively. In multivariate analysis, endovaginal recurrence and no irradiation history were favorable prognostic factors associated with OS (all p < 0.05), PFS (all p < 0.05), and LC (all p < 0.05). The area under the receiver operating characteristic (ROC) curve (AUC) of the recurrence pattern is larger than the stage of primary tumor (0.734 vs. 0.670). CONCLUSIONS: RT was an effective treatment with tolerable toxicity for vaginal recurrences of cervical cancer in patients with prior surgery. Recurrence pattern and irradiation history were important prognostic factors.

19.
Radiat Oncol ; 16(1): 144, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34348758

RESUMO

BACKGROUND: To assess the intra-fractional dosimetric variations of image-guided brachytherapy of cervical cancer. METHODS: A total of 38 fractions (9 patients) undergoing brachytherapy for cervical cancer underwent a CT scanning for treatment planning (planning CT) and a Cone-beam CT (CBCT) scanning immediately prior to delivery (pre-delivery CBCT). The variations of volumes as well as the dosimetric impact from treatment planning to delivery (intra-application) were evaluated. The dose volume histogram parameters including volume, D90 of high-risk clinical target volume (HRCTV) and D2cc of organs at risk (OARs) were recorded. RESULTS: The relative differences (mean ± 1SD) of the volume and D90 HRCTV across the two scans were - 2.0 ± 3.3% and - 1.2 ± 4.5%, respectively. The variations of D2cc for bladder, rectum, sigmoid and small intestine are - 0.6 ± 17.1%, 9.3 ± 14.6%, 7.2% ± 20.5% and 1.5 ± 12.6%, respectively. Most of them are statistically nonsignificant except the D2cc for rectum, which showed a significant increase (P = 0.001). Using 5% and 10% uncertainty of physical dose for HRCTV at a 6 Gy × 5 high-dose-rate schedule, the possibility of total equivalent doses in 2 Gy fractions (EQD2) lower than 85 Gy is close to 0% and 3%, respectively. Performing similar simulation at 15% and 20% uncertainty of a 4 Gy physical dose for OARs, the possibility of total EQD2 dose exceeding 75 Gy is about 70%. Less than 1% of the total EQD2 of OARs would exceed 80 Gy. CONCLUSIONS: Average intra-fractional dosimetric variation of HRCTV was small in an interval of less than 1 h, and the possibility of total EQD2 exceeding 85 Gy is higher than 97%. The intra-fractional dosimetric variations of OARs might result in an overdose for OARs in a single fraction or the whole treatment. It is necessary to detect unfavorable anatomical changes by re-imaging and take interventions to minimize applied doses and reduce the risk of complications.


Assuntos
Braquiterapia/métodos , Tomografia Computadorizada de Feixe Cônico/métodos , Órgãos em Risco/efeitos da radiação , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Guiada por Imagem/métodos , Neoplasias do Colo do Útero/radioterapia , Feminino , Seguimentos , Humanos , Prognóstico , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Neoplasias do Colo do Útero/diagnóstico por imagem , Neoplasias do Colo do Útero/patologia
20.
Small ; 17(39): e2102777, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34390190

RESUMO

Realizing efficiency and stable hydrogen production by water electrolysis under high current densities is essential to the forthcoming hydrogen economy. However, its industrial breakthrough is seriously limited by bifunctional catalysts with slow hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalytic processes. Herein, an ultralow Ru incorporated amorphous cobalt-based oxide (Ru-CoOx /NF), effectively driving the electrolysis of water at high current densities in alkaline water and seawater, is designed and constructed. In 1 m KOH, to reach the current density of 1000 mA cm-2 for HER and OER, it only needs 252 and 370 mV overpotentials, respectively, beyond commercial Pt/C and RuO2 catalysts. At the high current density, it also presents outstanding electrochemical stability. Then the electrolyzer apparatus assembled with Ru-CoOx /NF, just requires the ultra-low voltage of 2.2 and 2.62 V to support the current density of 1000 mA cm-2 in alkaline water and seawater electrolysis, respectively, for hydrogen production, better than that of the commercial Pt/C and RuO2 catalysts. This work demonstrates that Ru-CoOx /NF is one of the most promising catalysts for industrial applications and provides a possibility for exploration of high-current-density water electrocatalysis by changing the crystallinity of the catalyst.

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