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1.
Artigo em Inglês | MEDLINE | ID: mdl-34312760

RESUMO

Environment-friendly sound measures with high algal growth inhibition efficiency are required to control and eliminate CyanoHABs. This study examined the effects of protopine on growth, gene expression, and antioxidant system of the M. aeruginosa TY001 and explored possible damage mechanism. The results revealed that higher concentrations of protopine seriously inhibited the growth of M. aeruginosa. Quantitative real-time PCR analysis showed downregulated expression of stress response genes (prx and fabZ), and DNA repair gene (recA) on days 3 and 5. The activities of antioxidant enzymes were also decreased markedly, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Additionally, protopine stress can significantly increase the malondialdehyde (MDA) level in cells. In conclusion, oxidative damage and DNA damage are the main mechanisms of protopine inhibition on M. aeruginosa TY001. Our studies provide evidence that alkaloid compounds such as protopine may have a potential use value as components of aquatic management strategies.

2.
Ying Yong Sheng Tai Xue Bao ; 32(7): 2440-2448, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34313062

RESUMO

To examine the effects of land use change on soil stoichiometry, we selected four kinds of land use soils in northern Guangdong: forest land (FL), sloping orchard (SO), dry land terraces (DLT) and paddy terraces (PT) to explore the changes of the contents, stocks and stoichiometry of organic carbon, nitrogen and phosphorus in the 20 a process of transforming from forest land into terraced land. Results showed that land use significantly changed the contents and stoichiometric characteristics of soil carbon, nitrogen and phosphorus. With the increase of soil depth, organic carbon (OC) and total nitrogen (TN) contents of DLT and PT decreased significantly, while FL and SO showed a "V"-shaped change trend. There was no difference in total phosphorus (TP) content among the four land use types. The OC content of PT was the highest, with an average value of 12.36 g·kg-1, followed by FL (10.32 g·kg-1) and DLT (8.80 g·kg-1), while SO was the lowest (5.96 g·kg-1). TN content was decreased in order of PT (1.01 g·kg-1)>DLT (0.78 g·kg-1)>FL (0.66 g·kg-1)>SO (0.33 g·kg-1). TP content of DLT (0.71 g·kg-1) was the highest, and SO (0.22 g·kg-1) was the lowest. C:N was between 8.87 and 22.94, and SO was the highest. C:P was between 8.73 and 81.74, N:P was between 0.77 and 5.13, with both of which being the highest in FL. Land use, soil depth and their interaction significantly affected the contents, stocks, and stoichiometric ratio of soil carbon, nitrogen and phosphorus, with soil bulk density, pH, and clay content as important influencing factors. The research results could provide a scientific basis for land use of subtropical low mountain forest land and rational fertilization of terraced ecosystems.

3.
Artigo em Inglês | MEDLINE | ID: mdl-34216638

RESUMO

The biological damage caused by the environmental factors such as radiation and its control methods are one of the frontiers of life science research that has received widespread attention. Ionizing radiation can directly interact with target molecules (such as DNA, proteins and lipids) or decomposed by radiation from water, leading to changes in oxidative events and biological activities in cells. Liver is a radiation-sensitive organ, and its radiosensitivity is second only to bone marrow, lymph, gastrointestinal tissue, gonads, embryos and kidneys. In addition, as a key organ of mammals, liver performs a series of functions, including the production of bile, the metabolism of nutrients, the elimination of waste, the storage of glycogen, and the synthesis of proteins. Therefore, liver is prone to various pathophysiological changes. In this review, the effects of radiation on liver injury, its pathogenesis, bystander effect and the natural traditional Chinese medicine to protect the radiation induced liver damage are discussed.

4.
Molecules ; 26(14)2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34299577

RESUMO

Magnolol (MAG), a biphenolic neolignan, has various biological activities including antitumor effects. In this study, 15 MAG derivatives were semi-synthesized and evaluated for their in vitro anticancer activities. From these derivatives, compound 6a exhibited the best cytotoxic activity against four human cancer cell lines, with IC50 values ranging from 20.43 to 28.27 µM. Wound-healing and transwell assays showed that compound 6a significantly inhibited the migration and invasion of MDA-MB-231 cells. In addition, Western blotting experiments, performed using various concentrations of 6a, demonstrated that it downregulates the expression of HIF-1α, MMP-2, and MMP-9 in a concentration-dependent manner. Overall, these results suggest that substituting a benzyl group having F atoms substituted at the C2 position on MAG is a viable strategy for the structural optimization of MAG derivatives as anticancer agents.

5.
Artigo em Inglês | MEDLINE | ID: mdl-34310058

RESUMO

AIM: To analyze the relationships between the ultrasonographic features and the molecular subtypes of breast cancer in men and women. METHODS: Data were collected from 43 males and 80 females with breast cancer who were treated at our hospital. The following ultrasonographic characteristics of the tumors were evaluated: shape, orientation, margin, echo pattern, posterior features, calcifications, Color Doppler Flow Imaging, and Breast Imaging Reporting and Data System (BI-RADS) category. RESULTS: On ultrasound, a nonparallel orientation, noncircumscribed margin, and attenuating posterior features were associated with luminal A lesions. A parallel orientation (P = 0.002), circumscribed margin (P = 0.04), no change in posterior features (P < 0.001), and the BI-RADS 4 category (P = 0.001) were significantly associated with luminal B lesions. In the group with luminal A lesions, male patients were older (P = 0.001) and a greater number of the tumors exhibited a regular shape (P = 0.009), circumscribed margin (P < 0.001), no change in posterior features (P < 0.001), and the BI-RADS 4 category (P < 0.001) than those in female patients. Male patients were older (P < 0.001) and a greater number showed a no change in posterior features (P < 0.001), spotty blood flow (P = 0.002), and the BI-RADS 4 category (P < 0.001) than female patients with masses of the luminal B subtype. CONCLUSION: Obvious differences in the ultrasonographic and pathological features were noted between breast cancer in males and females, which provided the theoretical basis for the individualized treatment of breast cancer, particularly breast cancer in males.

6.
J Phys Chem Lett ; : 7053-7059, 2021 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-34291938

RESUMO

The "shuttle effect" and sluggish kinetics at cathode significantly hinder the further improvements of the lithium-sulfur (Li-S) battery, a candidate of next generation energy storage technology. Herein, machine learning based on high-throughput density functional theory calculations is employed to establish the pattern of polysulfides adsorption and screen the supported single-atom catalyst (SAC). The adsorptions are classified as two categories which successfully distinguish S-S bond breaking from the others. Moreover, a general trend of polysulfides adsorption was established regarding of both kind of metal and the nitrogen configurations on support. The regression model has a mean absolute error of 0.14 eV which exhibited a faithful predictive ability. Based on adsorption energy of soluble polysulfides and overpotential, the most promising SAC was proposed, and a volcano curve was found. In the end, a reactivity map is supplied to guide SAC design of the Li-S battery.

7.
Inorg Chem ; 2021 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-34291940

RESUMO

Metal-organic frameworks (MOFs) represent an ideal platform for the construction of highly active composite catalysts. However, loading metastable and/or multicomponent metal compounds into MOFs remains a synthetic bottleneck due to the great challenge of keeping the guest and matrix intact during the preparation of a composite. In this work, we develop a new impregnation reduction surface modification (IRSM) strategy to give a new composite catalyst CuCl@MIL-101(Cr), which is successfully postmodified by in situ construction of CuII defects on the surface of loaded CuCl inside MOF pores, leading to the new composite material CuII/CuI@MIL-101(Cr). The new dual-component composite catalyst exhibits a hierarchical structure and superior catalytic activity in C-C homocoupling of arylboronic acids under green conditions. This study presents a facile strategy for improving the catalytic activity by constructing defects on the surface of MOF-based catalysts as well as for forming multiple-component composite materials.

8.
Ann Palliat Med ; 10(6): 6694-6705, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34237972

RESUMO

BACKGROUND: To explore the feasibility and efficiency of posterior wedge osteotomy assisted by O-arm navigation treatment of ankylosing spondylitis (AS) patients with thoracolumbar fracture. METHODS: This is a case series study. A total of 16 cases of AS accompanied by thoracolumbar fractures from January 2012 to July 2015 were retrospectively analyzed. All patients underwent "posterior wedge osteotomy assisted by O-arm navigation". The operation time, blood loss volume, preoperative and postoperative visual analogue scale (VAS), American Spinal Injury Association (ASIA) classification, and spinal imaging parameters [Cobb angle, C7 plumb line (C7PL), and jaw-brow angle] were collected and analyzed. RESULTS: The operative time consumption was 120-350 mins and the intra-operative blood loss volume was 200-800 mL. No obvious postoperative complications occurred in any participants. The back pain of all participants was relieved, and the neurological functions of eight participants with spinal cord injury (SCI) were recovered in varying degrees except for one patient with severe SCI. The spinal deformities of the participants were corrected to varying degrees. The fracture sites of 16 participants were all healed, and there was no loosening or detachment of internal fixation during the 6-month follow-up period. CONCLUSIONS: Posterior wedge osteotomy assisted by O-arm navigation was shown to be a safe and effective method to treat AS accompanied by thoracolumbar fractures. This treatment strategy can accurately decompress and reduce the fracture and significantly correct the kyphosis, with good surgical effect.


Assuntos
Espondilite Anquilosante , Cirurgia Assistida por Computador , Humanos , Imageamento Tridimensional , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/cirurgia , Osteotomia , Estudos Retrospectivos , Espondilite Anquilosante/cirurgia , Vértebras Torácicas/cirurgia , Tomografia Computadorizada por Raios X , Resultado do Tratamento
9.
Sheng Li Xue Bao ; 73(3): 389-406, 2021 Jun 25.
Artigo em Chinês | MEDLINE | ID: mdl-34230942

RESUMO

As non-pharmaceutical interventions, non-invasive electrical neuromodulation techniques are promising in pain management. With many advantages, such as low costs, high usability, and non-invasiveness, they have been exploited to treat multiple types of clinical pain. Proper use of these techniques requires a comprehensive understanding of how they work. In this article, we reviewed recent studies concerning non-invasive electrical peripheral nerve stimulation (transcutaneous electrical nerve stimulation and transcutaneous vagus/vagal nerve stimulation) as well as electrical central nerve stimulation (transcranial direct current stimulation and transcranial alternating current stimulation). Specifically, we discussed their analgesic effects on acute and chronic pain, and the neural mechanisms thereof. We then contrasted the four kinds of nerve stimulation techniques, pointing out limitations of existing studies and proposing directions for future research. With more extensive and in-depth research to overcome these limitations, we shall witness more clinical applications of non-invasive electrical nerve stimulations to alleviate patients' pain and ease the crippling medical and economic burden imposed on patients, their families, and the entire society.


Assuntos
Dor Crônica , Estimulação Transcraniana por Corrente Contínua , Estimulação Elétrica Nervosa Transcutânea , Estimulação do Nervo Vago , Analgésicos , Humanos
10.
Artigo em Inglês | MEDLINE | ID: mdl-34279902

RESUMO

Particulate matter of 0.3 µm in diameter (PM0.3) poses a serious threat to the environment and human beings. Ultrathin and -light nanofibrous filters with excellent filtration properties can significantly prevent the detrimental effects of these particles. Here, we develop free-standing polyamide PA-66 ultrafine nanofiber papers for PM0.3 filtration using effective and scalable blow and electro-blow spinning techniques. The smallest average fiber diameter is 61.7 nm, which is 2-3 orders of magnitude smaller than that of conventional textiles. Poly(ethylene terephthalate) nonwovens are selected to fabricate free-standing nanofiber papers of various polymers, including polyamide, poly(methyl methacrylate), poly(vinylpyrrolidone), and poly(ethylene oxide) owing to the smooth surfaces of the nonwovens. This underlying principle can be used to create similar free-standing nanofiber papers from other commodity polymers in the future. Mechanisms of capturing particulate matter with different nanofiber morphologies are discussed. Salt and oil particulates are used to characterize the filtration properties. PA-66 papers are promising reusable filters owing to their mechanical particle-capture mechanism. The blow-spun PA-66 papers show filtration performance of 98.75% efficiency and a pressure drop of 125.44 Pa owing to the "slip" effect caused by the ultrasmall diameter. In the electro-blow spinning process, a supplementary voltage supply is conducive to separating nanofiber bundles into random-oriented nanofibers. Electro-blown spun papers possess an ultrahigh efficiency of 99.99% with a reduced areal density of 0.9 g m-2. These PA-66 papers can be used in a variety of applications, such as reusable personal protective equipment, industrial waste gas treatment, and central ventilation purification systems.

11.
Nat Chem ; 2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34282307

RESUMO

The development of innovative strategies for the synthesis of N-heterocyclic compounds is an important topic in organic synthesis. Ring expansion methods to form large N-heterocycles often involve the cycloaddition of strained aza rings with π bonds. However, in some cases such strategies suffer from some limitations owing to the difficulties in controlling the regioselectivity and the accessibility of specific π-bond synthons. Here, we report the development of a general ring expansion strategy that involves a formal cross-dimerization between three-membered aza heterocycles and three- and four-membered-ring ketones through synergistic bimetallic catalysis. These formal cross-dimerizations of two different strained rings are efficient and scalable, and provide a straightforward and broadly applicable means of assembling diverse N-heterocycles, such as 3-benzazepinones, dihydropyridinones and uracils, which are versatile units in numerous drugs and biologically active compounds. Preliminary mechanistic studies revealed that the C-C bond of strained ring ketones is first cleaved by the Pd0 species during the reaction.

12.
Invest New Drugs ; 2021 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-34287773

RESUMO

Paraneoplastic neurologic syndromes(PNSs) caused by immune checkpoint inhibitors(ICIs) is rare and requires clinicians to differentiate between disease progression and immune-related adverse effects(irAEs). We hereby report the case of immune-related myelitis accompanied by positive paraneoplastic autoantibodies following durvalumab treatment for extensive-stage small cell lung cancer (ES-SCLC). A 70-year-old Chinese woman with ES-SCLC was administered durvalumab with etoposid-platinum(EP) as first-line treatment. Four cycles after treatment with EP plus ICI, she developed immune-related myelitis with positive paraneoplastic autoantibodies (CV2, SOX1, ZIC4). Spinal MRI showed diffuse abnormal signal shadow in the cervicothoracic spinal cord. She was discontinued for chemotherapy, and treated with high-dose steroids, intravenous immunoglobulin and plasmapheresis, maintenance therapy with steroids resulted in a favorable neurologic outcome. This is the first report of durvalumab-related PNSs. We supposed that the development of paraneoplastic myelitis was causally related to immune activation by durvalumab. Prompt diagnosis and therapeutic intervention are essential for the effective treatment of paraneoplastic myelitis.

13.
Small ; : e2101616, 2021 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-34270865

RESUMO

Phase controllable synthesis of 2D materials is of significance for tuning related electrical, optical, and magnetic properties. Herein, the phase-controllable synthesis of tetragonal and hexagonal FeTe nanoplates has been realized by a rational control of the Fe/Te ratio in a chemical vapor deposition system. Using density functional theory calculations, it has been revealed that with the change of the Fe/Te ratio, the formation energy of active clusters changes, causing the phase-controllable synthesis of FeTe nanoplates. The thickness of the obtained FeTe nanoplates can be tuned down to the 2D limit (2.8 nm for tetragonal and 1.4 nm for hexagonal FeTe). X-ray diffraction pattern, transmission electron microscopy, and high resolution scanning transmission electron microscope analyses exhibit the high crystallinity of the as-grown FeTe nanoplates. The two kinds of FeTe nanoflakes show metallic behavior and good electrical conductivity, featuring 8.44 × 104 S m-1 for 9.8 nm-thick tetragonal FeTe and 5.45 × 104 S m-1 for 7.6 nm-thick hexagonal FeTe. The study provides an efficient and convenient route for tailoring the phases of FeTe nanoplates, which benefits to study phase-sensitive properties, and may pave the way for the synthesis of other multiphase 2D nanosheets with controllable phases.

14.
Arch Insect Biochem Physiol ; : e21837, 2021 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-34293199

RESUMO

The olfactory system must detect and discriminate various semiochemicals in the environment. In response to such diversity, insects have evolved a family of odorant-gated ion channels composed of a common receptor (coreceptor, Orco) and a ligand-binding tuning odorant receptor (OR) that confers odour specificity. This study aims to examine the expression pattern of Orco gene of Grapholita molesta (GmolOrco) and to elucidate the role of GmolOrco in detecting G. molesta sex pheromone and green leaf volatiles by using gene silencing via RNA interference (RNAi) coupled antennal electrophysiological (EAG). Multiple sequence alignment showed that GmolOrco shared high sequence similarities with the Orco ortholog of lepidopterans. The results of real-time quantitative PCR detection demonstrated that GmolOrco was predominantly expressed in adult antennae and had the highest expression quantity in adult period among the different developmental stages. Compared with the noninjected controls, GmolOrco expression in GmolOrcodouble-stranded RNA (dsRNA)-injected males was reduced to 39.92% and that in females was reduced to 40.43%. EAG assays showed that the responses of GmolOrco-dsRNA injected males to sex pheromones (Z)-8-dodecenyl acetate (Z8-12:OAc) and (Z)-8-dodecenyl alcohol (Z8-12:OH) were significantly reduced, and the GmolOrco-dsRNA-injected female to green leaf volatile (Z)-3-hexenyl acetate also significantly declined. We inferred that Orco-mediated olfaction was different in male and female G. molesta adults and was mainly involved in recognizing the sex pheromones released by female moths.

15.
Artigo em Inglês | MEDLINE | ID: mdl-34281046

RESUMO

Grassland ecosystems are increasingly threatened by pressures from climate change and intensified human activity, especially in the arid region of Central Asia. A comprehensive understanding of the ecological environment changes is crucial for humans to implement environmental protection measures to adapt to climate change and alleviate the contradiction between humans and land. In this study, fractional vegetation coverage (FVC), leaf area index (LAI), gross primary productivity of vegetation (GPP), land surface temperature (LST), and wetness (WET) were retrieved from Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite remote sensing products in 2008 and 2018. Principal component analysis (PCA) was used to establish the MODIS data-based ecological index (MODEI) in the study area, and the spatial differentiation characteristics and driving mechanism of ecological quality in the last ten years were explored. The results showed that: (1) FVC, GPP, LAI, and WET had positive effects on the ecological environment, while LST had a negative impact on the ecological environment. FVC and GPP were more significant than other indicators. (2) The MODEI showed a spatial pattern of "excellent in the north and poor in the south" and changed from north to south in the study area. (3) From 2008 to 2018, the average MODEI of Fuyun County increased from 0.292 to 0.303, indicating that the ecological quality in Fuyun County became better overall. The improved areas were mainly located in the summer pastures at higher elevations. In comparison, the deteriorated areas were concentrated in the spring and autumn pastures and winter pastures at lower elevations. The areas where the ecological environment had obviously improved and degraded were distributed along the banks of the Irtysh River and the Ulungur River. (4) With the increase in precipitation and the decrease in grazing pressure, the MODEI of summer pasture was improved. The deterioration of ecological environment quality in spring and autumn pastures and winter pastures was related to the excessive grazing pressure. The more significant changes in the MODEI on both sides of the river were associated with implementing the herdsmen settlement project. On the one hand, the implementation of newly settled villages increased the area of construction land on both sides of the river, which led to the deterioration of ecological quality; on the other hand, due to the increase in cropland land and the planting of artificial grasses along the river, the ecological quality was improved. The study offers significant information for managers to make more targeted ecological restoration efforts in ecologically fragile areas.

16.
Plant Biotechnol J ; 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34265153

RESUMO

Sclerotinia sclerotiorum and Botrytis cinerea are typical necrotrophic pathogens that can attack more than 700 and 3000 plant species, respectively, and cause huge economic losses across numerous crops. In particular, the absence of resistant cultivars makes the stem rot because of S. sclerotiorum the major threat of rapeseed (Brassica napus) worldwide along with Botrytis. Previously, we identified an effector-like protein (SsSSVP1) from S. sclerotiorum and a homologue of SsSSVP1 on B. cinerea genome and found that SsSSVP1 could interact with BnQCR8 of rapeseed, a subunit of the cytochrome b-c1 complex. In this study, we found that BnQCR8 has eight homologous copies in rapeseed cultivar Westar and reduced the copy number of BnQCR8 using CRISPR/Cas9 to improve rapeseed resistance against S. sclerotiorum. Mutants with one or more copies of BnQCR8 edited showed strong resistance against S. sclerotiorum and B. cinerea. BnQCR8-edited mutants did not show significant difference from Westar in terms of respiration and agronomic traits tested, including the plant shape, flowering time, silique size, seed number, thousand seed weight and seed oil content. These traits make it possible to use these mutants directly for commercial production. Our study highlights a common gene for breeding of rapeseed to unravel the key hindrance of rapeseed production caused by S. sclerotiorum and B. cinerea. In contrast to previously established methodologies, our findings provide a novel strategy to develop crops with high resistance against multiple pathogens by editing only a single gene that encodes the common target of pathogen effectors.

17.
J Neurosurg Spine ; : 1-8, 2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34243159

RESUMO

OBJECTIVE: Conflicting reports exist about whether transforaminal lumbar interbody fusion (TLIF) induces lordosis or kyphosis, ranging from decreasing lordosis by 3.71° to increasing it by 18.8°. In this study, the authors' aim was to identify factors that result in kyphosis or lordosis after TLIF. METHODS: A single-center, retrospective study of open TLIF without osteotomy for spondylolisthesis with a minimum 2-year follow-up was undertaken. Preoperative and postoperative clinical and radiographic parameters and cage specifics were collected. TLIFs were considered to be "lordosing" if postoperative induction of lordosis was > 0° and "kyphosing" if postoperative induction of lordosis was ≤ 0°. RESULTS: A total of 137 patients with an average follow-up of 52.5 months (range 24-130 months) were included. The overall postoperative disc angle (DA) and segmental lordosis (SL) increased by 1.96° and 1.88° (p = 0.003 and p = 0.038), respectively, whereas overall lumbar lordosis remained unchanged (p = 0.133). Seventy-nine patients had lordosing TLIFs with a mean SL increase of 5.72° ± 3.97°, and 58 patients had kyphosing TLIFs with a mean decrease of 3.02° ± 2.98°. Multivariate analysis showed that a lower preoperative DA, lower preoperative SL, and anterior cage placement were correlated with the greatest increase in postoperative SL (p = 0.040, p < 0.001, and p = 0.035, respectively). There was no difference in demographics, cage type or height, or spinopelvic parameters between the groups (p > 0.05). Linear regression showed that the preoperative DA and SL correlated with SL after TLIF (R2 = 0.198, p < 0.001; and R2 = 0.2931, p < 0.001, respectively). CONCLUSIONS: Whether a TLIF induces kyphosis or lordosis depends on the preoperative DA, preoperative SL, and cage position. Less-lordotic segments became more lordotic postoperatively, and highly lordotic segments may lose lordosis after TLIF. Cages placed more anteriorly were associated with more lordosis.

18.
Rev Sci Instrum ; 92(5): 053002, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-34243279

RESUMO

Transient absorption (TA) spectroscopy is considered as a powerful technique that reflects the ultrafast dynamics of photogenerated carriers in photoelectric and photocatalysis materials. However, limited by its sensitivity, the photogenerated carrier density in TA measurements of solar energy materials is usually much higher than that in the real working condition. Here, we present a combination of kHz macro-pulse and MHz micro-pulse technique for an ultrahigh sensitive TA spectrometer, which improves the sensitivity to the 10-7 level of ΔOD. It enables us to study ultrafast carrier dynamics pumped by very low power, which can avoid the influence of many-body interactions and the nonlinear effect associated with high carrier density. This work provides a novel TA method with ultrahigh sensitivity, which will play an important role in investigating the carrier dynamics of semiconductors in the working condition.

19.
Artigo em Inglês | MEDLINE | ID: mdl-34245074

RESUMO

A new family of carbon-bound boron enolates, generated by a kinetically controlled halogen exchange between chlorocatecholborane and silylketene acetals, is described. These C-boron enolates are demonstrated to activate 1,3-enyne substrates in the presence of a Pd(0)/Senphos ligand complex, resulting in the first examples of a carboboration reaction of an alkyne with enolate-equivalent nucleophiles. Highly substituted dienyl boron building blocks are produced in excellent site-, regio-, and diastereoselectivity by the described catalytic  cis -carboboration reaction.

20.
Biomed Mater Eng ; 2021 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-34250923

RESUMO

BACKGROUND: Transforming growth factor-ß1 (TGF-ß1) plays an important role in chondrocyte growth and the synthesis of extracellular matrix (ECM). Due to the rapid metabolism, controlled release systems for TGF-ß1 have attracted increasing interest recently. OBJECTIVE: In this study, a silk fibroin (SF)/chitosan (CS) scaffold incorporated with TGF-ß1-loaded microspheres (MSs) was created for cartilage reparation. METHOD: The optimal proportion of the SF/CS composite scaffold was determined by evaluating their micromorphology and the proliferation rate of fibroblasts on the surface. Then, SF/CS/TGF-ß1-loaded MS scaffolds were prepared by the adsorption method. TGF-ß1 release capacity, degradation patterns, cytocompatibility and in vivo implantation were evaluted. RESULTS: The SF/CS/TGF-ß1-loaded MS scaffold showed good TGF-ß1 release over more than 16 days, which could sequentially stimulate chondrocyte synthetic activity. In vitro cell proliferation experiments showed the SF/CS/TGF-ß1-loaded MS scaffold could promote chondrocytes adhesion, growth, proliferation and maintained the cellular morphology. An in vivo study demonstrated that a low inflammatory response was observed in rats and that the materials exhibited good biocompatibility. CONCLUSION: the results indicated that our SF/CS/TGF-ß1-loaded MS scaffold constitute a promising therapeutic option for cartilage reparation.

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