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1.
Opt Lett ; 49(5): 1261-1264, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38426988

RESUMO

A terahertz metamaterial waveguide (meta-waveguide) and a meta-waveguide-based lens-free imaging system are presented. The meta-waveguide not only inherits the low-loss transmission performance of a waveguide but also breaks through the diffraction limit under the action of the metamaterial, achieving subwavelength focusing. The focusing distance is far greater than the Rayleigh length, thus enabling far-field scanning imaging. For verification, a metal ring-based meta-waveguide was fabricated by 3D printing and metal cladding technology. Then, a transmission scanning imaging system working at 0.1 THz was built. High quality terahertz images with a resolution of 1/3 of the wavelength were obtained by placing the imaging targets at the focus and performing two-dimensional scanning. The focusing and transmission of terahertz wave in the meta-waveguide were simulated and analyzed.

2.
Chin J Nat Med ; 22(1): 15-30, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38278556

RESUMO

Oleanolic acid (OA), a pentacyclic triterpenoid, exhibits a broad spectrum of biological activities, including antitumor, antiviral, antibacterial, anti-inflammatory, hepatoprotective, hypoglycemic, and hypolipidemic effects. Since its initial isolation and identification, numerous studies have reported on the structural modifications and pharmacological activities of OA and its derivatives. Despite this, there has been a dearth of comprehensive reviews in the past two decades, leading to challenges in subsequent research on OA. Based on the main biological activities of OA, this paper comprehensively summarized the modification strategies and structure-activity relationships (SARs) of OA and its derivatives to provide valuable reference for future investigations into OA.


Assuntos
Ácido Oleanólico , Triterpenos , Relação Estrutura-Atividade , Anti-Inflamatórios/farmacologia , Antibacterianos/farmacologia
3.
Quant Imaging Med Surg ; 13(8): 5119-5129, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37581076

RESUMO

Background: With the continuous development of machine vision and imaging technology and its application in computer-aided diagnosis, it is clinically important to use computer technology to assist physicians in accurate cataract surgery. The capsulorhexis directly affects the outcome of cataract surgery, therefore, we design a method to automatically determine the virtual boundary of capsulorhexis for cataract surgery planning and tracking in-vivo to help surgeons achieve a more ideal capsulotomy geometry. Methods: In this study, an effective method was proposed to detect and display the location of capsulorhexis in cataract videos in-vivo. The initial step was locating the entire eye area by analyzing the connected components of the mirror reflective points in the image in the cataract surgery video. Then, an operator was designed for ridge edge variation and used to extract pupil edge features. Lastly, circular Hough transform was used to detect the pupillary margin and calculate the boundary between the scleral limbus and the virtual capsulorhexis border in accordance with the pupillary margin and finally displayed it in-vivo during cataract surgery. Results: The method was tested on eight videos of cataract surgery and the results showed that 98.52% accuracy was achieved in the localization of the specular reflection point. We compared the proposed operator with the Sobel, Scharr, Laplace and Canny operators and the results showed that our operator achieved the smallest mean square error with the greatest structural similarity. Conclusions: The analysis demonstrated that the proposed operator outperformed other operators in detection and achieved satisfactory results in the videos of actual cataract surgeries.

4.
J Enzyme Inhib Med Chem ; 38(1): 2192439, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36950955

RESUMO

A series of OA-tacrine hybrids with the alkylamine linker was designed, synthesized, and evaluated as effective cholinesterase inhibitors for the treatment of Alzheimer's disease (AD). Biological activity results demonstrated that some hybrids possessed significant inhibitory activities against acetylcholinesterase (AChE). Among them, compounds B4 (hAChE, IC50 = 14.37 ± 1.89 nM; SI > 695.89) and D4 (hAChE, IC50 = 0.18 ± 0.01 nM; SI = 3374.44) showed excellent inhibitory activities and selectivity for AChE as well as low nerve cell toxicity. Furthermore, compounds B4 and D4 exhibited lower hepatotoxicity than tacrine in cell viability, apoptosis, and intracellular ROS production for HepG2 cells. These properties of compounds B4 and D4 suggest that they deserve further investigation as promising agents for the prospective treatment of AD.


Assuntos
Doença de Alzheimer , Doença Hepática Induzida por Substâncias e Drogas , Humanos , Tacrina/farmacologia , Inibidores da Colinesterase/farmacologia , Doença de Alzheimer/tratamento farmacológico , Acetilcolinesterase/metabolismo , Relação Estrutura-Atividade
5.
Bioorg Chem ; 134: 106441, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36854233

RESUMO

A novel series of N-methyl-propargylamine derivates were designed, synthesized, and evaluated as isoform-selective monoamine oxidases (MAO) inhibitors for the treatment of nervous system diseases. The in vitro studies showed some of the compounds exhibited considerable MAO-A selective inhibitory activity (IC50 of 14.86-17.16 nM), while some of the others exhibited great MAO-B selective inhibitory activity (IC50 of 4.37-17.00 nM). Further studies revealed that compounds A2 (IC50 against MAO-A: 17.16 ± 1.17 nM) and A5 (IC50 against MAO-B: 17.00 ± 1.10 nM) had significant abilities to protect PC12 cells from H2O2-induced apoptosis and reactive oxygen species (ROS) production. The parallel artificial membrane permeability assay showed A2 and A5 would be potent to cross the blood-brain barrier. The results indicated that A2 showed potential use in the therapy of MAO-A related diseases, such as depression and anxiety; while A5 exhibited promising ability in the treatment of MAO-B related diseases, such as Alzheimer's disease and Parkinson's disease.


Assuntos
Doença de Alzheimer , Peróxido de Hidrogênio , Ratos , Animais , Relação Estrutura-Atividade , Inibidores da Monoaminoxidase/farmacologia , Monoaminoxidase/metabolismo
6.
PeerJ ; 11: e16523, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38505381

RESUMO

Background: Gastric cancer (GC) stem cells play an important role in GC progression. Circular RNAs (circRNAs) act as microRNA (miRNA) sponges and inhibit the biological function of miRNAs in GC cytoplasm. MiRNAs also participate in GC progress. circ_0051246 was shown to be associated with miR-375 after analyzing GC microarray data GSE78091 and GSE83521. The oncoprotein Yes-associated protein 1 (YAP1) is targeted by miR-375 and can be inactivated via the Hippo tumor suppressor pathway. Due to insufficient research on circ_0051246, this study aimed to investigate its relationship with miR-375 and YAP1 in cancer stem cells (CSCs). Methods: SGC-7901 CSCs were used to establish knockdown/overexpression models of circ_0051246, miR-375, and YAP1. Malignant phenotypes of CSCs were assessed using Cell Counting Kit 8, colony/sphere formation, 5-Ethynyl-2'-deoxyuridine assay, flow cytometry, Transwell, and wound healing assays. To detect the interactions between circ_0051246, miR-375, and YAP1 in CSCs, a dual-luciferase reporter assay and fluorescence in situ hybridization were performed. In addition, 24 BALB/c nude mice were used to establish orthotopic xenograft tumor models. Four groups of mice were injected with CSCs (1 × 106 cells/100 µL) with circ_0051246 knockdown, miR-375 overexpression, or their respective control cells, and tumor progression and gene expression were observed by hematoxylin-eosin staining, immunohistochemistry. Western blot and quantitative real-time PCR were utilized to examine protein and gene expression, respectively. Results: Circ_0051246 silencing reduced viability, promoted apoptosis, and inhibited proliferation, migration and invasion of CSCs. The functional effects of miR-375 mimics were comparable to those of circ_0051246 knockdown; however, the opposite was observed after miR-375 inhibitors treatment of CSCs. Furthermore, circ_0051246-overexpression antagonized the miR-375 mimics' effects on CSCs. Additionally, YAP1 overexpression promoted CSC features, such as self-renewal, migration, and invasion, inhibited apoptosis and E-cadherin levels, and upregulated the expression of N-cadherin, vimentin, YAP1, neurogenic locus notch homolog protein 1, and jagged canonical notch ligand 1. Conversely, YAP1-silenced produced the opposite effect. Moreover, miR-375 treatment antagonized the malignant effects of YAP1 overexpression in CSCs. Importantly, circ_0051246 knockdown and miR-375 activation suppressed CSC tumorigenicity in vivo. Conclusion: This study highlights the promotion of circ_0051246-miR-375-YAP1 axis activation in GC progression and provides a scientific basis for research on the molecular mechanism of CSCs.


Assuntos
MicroRNAs , Neoplasias , Animais , Humanos , Camundongos , Proteínas Adaptadoras de Transdução de Sinal/genética , Hibridização in Situ Fluorescente , Camundongos Nus , MicroRNAs/genética , RNA Circular/genética , Fatores de Transcrição/genética , Proteínas de Sinalização YAP/metabolismo
7.
Int J Mol Sci ; 23(24)2022 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-36555409

RESUMO

A series of novel 1,3,4-oxadiazole-artemisinin hybrids have been designed and synthesized. An MTT assay revealed that most of tested hybrids showed more enhanced anti-proliferative activities than artemisinin, among which A8 had the superior potency with IC50 values ranging from 4.07 µM to 9.71 µM against five tested cancer cell lines. Cell colony formation assays showed that A8 could inhibit significantly more cell proliferation than artemisinin and 5-fluorouracil. Further mechanism studies reveal that A8 induces apoptosis and ferroptosis in MCF-7 cells in a dose-dependent manner, and CYPs inhibition assays reveal that A8 has a moderate inhibitory effect on CYP1A2 and CYP3A4 in the human body at 10 µM. The present work indicates that hybrid A8 may merit further investigation as a potential therapeutic agent.


Assuntos
Antineoplásicos , Artemisininas , Ferroptose , Humanos , Células MCF-7 , Estrutura Molecular , Antineoplásicos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Apoptose , Artemisininas/farmacologia , Proliferação de Células , Relação Estrutura-Atividade , Linhagem Celular Tumoral
8.
Org Lett ; 24(45): 8310-8315, 2022 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-36342358

RESUMO

Collective total syntheses of 10 benzo[c]phenanthridines were achieved on the basis of the construction of rings C and B through sequential transition metal-catalyzed reactions and flexible condition-controlled Mannich reaction via three pots in 25-34% yields, which provided an efficient route to benzo[c]phenanthridines via a pot-economic approach.


Assuntos
Alcaloides , Elementos de Transição , Fenantridinas , Catálise
9.
J Phys Chem Lett ; 13(42): 9983-9990, 2022 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-36263973

RESUMO

The emerging matter category of liquid-matter ferroelectrics, i.e., ferroelectric nematics, demonstrates an unprecedented combination of fluidity and spontaneous polarization. However, unlike traditional ferroelectrics, the field-switched polarization at zero-field cannot be conserved, so the memory effect remains challenging. Here we report another new type of ferroelectric liquid crystal state, dubbed the ferroelectric smectic A phase, where the polarization is longitudinally coupled to the smectic quasi-layer order. With higher packing density, the phase exhibits higher values of refractive anisotropy and spontaneous polarization compared to the ferroelectric nematics. A delicate balance between the liquid crystal elasticity and flow viscosity enables both the switching and memory of the polarization field, thus opening the door toward realizing liquid-matter ferroelectric memory devices.

10.
Bioorg Chem ; 129: 106213, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36308854

RESUMO

Inosine 5'-monophosphate dehydrogenase (IMPDH; EC1.1.1.205) is the rate-limiting enzyme of GMP biosynthesis. The inhibition of IMPDH limits the growth and survival of tumors. Based on the systematic summary of clinical IMPDH inhibitors, 38 acrylamide derivatives with differently substituted indoles at the 3-position as the core scaffold were designed and synthesized. In addition, the actions of these compounds at the enzyme and cellular levels were evaluated. An MTT assay with different kinds of cells was used to assess the cytotoxic activities of compounds 14e and 14n, which displayed potent hIMPDH2 inhibitory activities (IC50 = 4.207 and 2.948 µM, respectively). Biological evaluation indicated that target compounds 14e and 14n displayed the most significant effects on SW480 human colon cancer cells (IC50 = 15.34 ± 0.06 and 15.31 ± 0.09 µM, respectively), and it was determined that these compounds are effective and valuable IMPDH inhibitors for cancer intervention.


Assuntos
Acrilamida , Antineoplásicos , Humanos , Acrilamida/farmacologia , IMP Desidrogenase , Inibidores Enzimáticos/farmacologia , Antineoplásicos/farmacologia , Indóis/farmacologia
11.
Front Microbiol ; 13: 983963, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36071964

RESUMO

Bloodstream infection (BSI) caused by Acinetobacter baumannii poses a serious threat to health and is correlated with high mortality in patients with hospital-acquired infections, so the molecular epidemiology and antimicrobial resistance characteristics of this pathogen urgently need to be explored. A. baumannii isolates from BSI patients were collected in three tertiary hospitals in northwest China from 2009 to 2018. Antimicrobial susceptibility testing was used to determine the MICs of the A. baumannii isolates. Whole-genome sequencing based on the Illumina platform was performed for molecular epidemiological analyses and acquired resistance gene screening. The efflux pump phenotype was detected by examining the influence of an efflux pump inhibitor. The expression of efflux pump genes was evaluated by RT-PCR. In total, 47 A. baumannii isolates causing BSI were collected and they presented multidrug resistance, including resistance to carbapenems. Clone complex (CC) 92 was the most prevalent with 30 isolates, among which a cluster was observed in the phylogenetic tree based on the core genome multi-locus sequence type, indicating the dissemination of a dominant clone. BSI-related A. baumannii isolates normally harbour multiple resistance determinants, of which oxacillinase genes are most common. Except for the intrinsic bla OXA-51 family, there are some carbapenem-resistant determinants in these A. baumannii isolates, including bla OXA-23, which is encoded within the Tn2006, Tn2008 or Tn2009 transposon structures and bla OXA-72. The transfer of bla OXA-72 was suggested by XerC/D site-specific recombination. The AdeABC efflux pump system contributed to carbapenem resistance in A. baumannii isolates, as evidenced by the high expression of some of its encoding genes. Both the clone dissemination and carbapenem resistance mediated by oxacillinase or efflux pumps suggest an effective strategy for hospital infection control.

13.
Int J Ophthalmol ; 15(6): 924-931, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35814895

RESUMO

AIM: To investigate the binocular intraocular lens (IOL) power difference in eyes with short, normal, and long axial lengths (AL) using Lenstar LS 900 optical biometry. METHODS: A total of 716 (1432 eyes) participants were included. The groups were categorized into short (group A: AL<22 mm), normal (group B: 22 mm≤AL≤25 mm), and long AL groups (group C: AL>25 mm). The central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), AL, anterior corneal keratometry, white-to-white (WTW), pupil diameter (PD), as well as IOL power calculated using embedded Barrett formula were assessed. Bland-Altman plots were used to test the agreement of the binocular parameters. RESULTS: In group A, the CCT of the right eye was significantly thinner than that of the left eye (P=0.044) with a difference of -2±8 µm [95% limits of agreement (LoA), -17.8 to 13.2 µm]. For group B, the PD and IOL power in the right eye were significantly lower than those of the left eye (P=0.001, <0.001) with a difference of -0.05±0.32 mm (95%LoA, -0.68 to 0.58 mm) and -0.18±1.01 D (95%LoA, -2.2 to 1.8 D). The AL of right eye was longer than that of the left eye (P=0.002) with a difference of 0.04±0.25 mm (95%LoA, -0.45 to 0.52 mm). No significant difference was observed for all the binocular parameters in group C. The percentage of participants with binocular IOL power difference within ±0.5 D were 62% (31/50), 68.3% (339/496), and 38.8% (66/170) in groups A, B, and C, respectively. CONCLUSION: The binocular parameters related to IOL power are in good agreement, but the binocular IOL power difference of more than half of participants with long AL is more than 0.50 D.

14.
J Clin Med ; 11(13)2022 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-35806863

RESUMO

Background: This study investigates the incidence and risk factors for the development of Berger's space (BS) after uneventful phacoemulsification based on swept-source optical coherence tomography (SS-OCT). Methods: Cataractous eyes captured using qualified SS-OCT images before and after uneventful phacoemulsification cataract surgery were included. Six high-resolution cross-sectional anterior segment SS-OCT images at 30° intervals were used for BS data measurements. BS width was measured at three points on each scanned meridian line: the central point line aligned with the cornea vertex and two point lines at the pupil's margins. Results: A total of 223 eyes that underwent uneventful cataract surgery were evaluated. Preoperatively, only two eyes (2/223, 0.9%) were observed to have consistent BS in all six scanning directions. BS was observed postoperatively in 44 eyes (44/223, 19.7%). A total of 13 eyes (13/223, 5.8%) with insufficient image quality, pupil dilation, or lack of preoperative image data were excluded from the study. A total of 31 postoperative eyes with BS and 31 matched eyes without BS were included in the final data analysis. The smallest postoperative BS width was in the upper quadrant of the vertical meridian line (90°), with a mean value of 280 µm. The largest BS width was observed in the opposite area of the main clear corneal incision, with a mean value >500 µm. Conclusions: Uneven-width BS is observable after uneventful phacoemulsification. Locations with a much wider BS (indirect manifestation of Wieger zonular detachment) are predominantly located in the opposite direction to the main corneal incisions.

15.
Front Microbiol ; 13: 899024, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35756010

RESUMO

Salmonella is a major zoonotic pathogen, which usually contaminates food resulting in salmonellosis in humans. Exploring the characteristics and origins of Salmonella is essential in formulating prevention and control measures for Salmonella infection. We used slide agglutination, antimicrobial susceptibility testing, and whole-genome sequencing to analyze and compare Salmonella's phenotype, genotyping diversity, and genetic relatedness from livestock meat and diarrhea patients in Hanzhong, China, from 2018 to 2020. Totally 216 Salmonella enterica isolates were screened from frozen whole chicken carcasses (44.3%, 70/158), frozen raw ground pork (36.2%, 59/163), and diarrhea patients (4.4%, 87/1964). Salmonella Typhimurium was the dominant serotype. Notably, compared with other sources, isolates obtained from frozen whole chicken carcasses showed significant resistance to third-generation cephalosporin and fluoroquinolones (p < 0.05). All strains were assigned into 36 sequence types (STs) and two novel STs, and an excellent consistency was observed between ST and serotype. Genomic data revealed that extended-spectrum ß-lactamase genes were responsible for third-generation cephalosporin resistance in 52 Salmonella strains, and the most predominant resistance determinant was bla CTX-M. Furthermore, of the 60 ciprofloxacin-resistant isolates, five single-base mutations in quinolone resistance-determining regions were identified in gyrA or parC, and the plasmid-mediated quinolone resistance gene aac(6')Ib-cr was most often detected. The cgMLST clusters show that five clusters among four serotypes (including S. Typhimurium, S. London, S. Derby, and S. Agona) cover samples from diarrhea patients and livestock meat pathway isolate, indicating a possibility of cross-host transmission. In conclusion, the livestock meat isolates have a higher level of resistance than diarrhea patients' isolates and could be an essential source of human Salmonella infection.

16.
Bioorg Chem ; 123: 105769, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35405572

RESUMO

The inhibition of programmed cell death-1/programmed cell death-ligand 1 (PD-1/PD-L1) interaction by monoclonal antibodies (mAbs) has achieved promising outcomes in cancer immunotherapy. Due to the inherent deficiencies of mAbs drugs, such as high cost of treatment, immunogenicity, poor pharmacokinetics and penetration of solid tumors, researchers are encouraged to develop small molecule inhibitors, to overcome mAbs drugs' deficiencies and change the situation where small molecule drugs are not available on the market. Herein, we reported a series of benzo[d]isothiazole derivatives targeting the PD-1/PD-L1 interaction through "ring fusion" strategy using BMS-202 as a starting point. Among them, compound D7 exhibited the best inhibitory activity with an IC50 value of 5.7 nM by homogeneous time-resolved fluorescence (HTRF) binding assay. In immunotoxicity analysis, D7 showed low cytotoxicity to Jurkat T cells in CCK-8 assay compared to BMS-202. The binding mode between D7 and PD-L1 protein was explored by molecular docking and molecular dynamics (MD) simulations, which revealed crucial chemical groups, such as biphenyl group interacting with Ile54A, Tyr56A, Met115A, Ala121A, Ile54B, Met115B, Ala121B and Tyr123B by hydrophobic interactions, bromobenzene moiety forming π-π stacking interaction with Tyr56B, as well as l-serine moiety forming hydrogen bond (H-bond) and salt bridge interactions with Asp122A and Lys124A. Furthermore, molecular modeling studies showed that D7 is likely to bind to the FA8 (fatty acid 8) binding site of human serum albumin (HSA). Taken together, D7 significantly inhibits the PD-1/PD-L1 interaction with low cytotoxicity, indicating that D7 is a promising starting point for further drug development in cancer immunotherapy.


Assuntos
Antígeno B7-H1 , Neoplasias , Apoptose , Humanos , Ligantes , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Receptor de Morte Celular Programada 1/química , Receptor de Morte Celular Programada 1/metabolismo , Relação Estrutura-Atividade
17.
Chin J Integr Med ; 28(9): 817-822, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34241804

RESUMO

OBJECTIVE: To study the mechanism of Shengmai Injection (SMI, ) on anti-sepsis and protective activities of intestinal mucosal barrier. METHODS: The contents of 11 active components of SMI including ginsenoside Rb1, Rb2, Rb3, Rd, Re, Rf, Rg1, Rg2, ophioposide D, schisandrol A and schisantherin A were determined using ultra-performance liquid chromatography. Fifty mice were randomly divided into the blank, the model, the low-, medium- and high-dose SMI groups (0.375, 0.75, 1.5 mL/kg, respectively) by random number table, 10 mice in each group. In SMI group, SMI was administrated to mice daily via tail vein injection for 3 consecutive days, while the mice in the blank and model groups were given 0.1 mL of normal saline. One hour after the last SMI administration, except the blank group, the mice in other groups were intraperitoneally injected with lipopolysaccharide (LPS) saline solution (2 mL/kg) at a dosage of 5 mL/kg for development of endotoxemia mice model. The mice in the blank group were given the same volume of normal saline. Inflammatory factors including interferon-γ (INF-γ), tumor necrosis factor-α (TNF-α), interleukin (IL)-2 and IL-10 were measured by flow cytometry. Myosin light-chain kinase (MLCK), nuclear factor κB (NF-κB) levels, and change of Occludin proteins in jejunum samples were analyzed by Western blot. RESULTS: The decreasing trends of INF-γ, TNF-α and IL-2 were found in serum of SMI treatment groups. In SMI-treated mice, the content of Occludin increased and MLCK protein decreased compared with the model group (P<0.05 or P<0.01). The content of cellular and nuclear NF-κB did not change significantly (P>0.05). CONCLUSION: SMI may exert its anti-sepsis activity mainly through NF-κB-pro-inflammatory factor-MLCK-TJ cascade.


Assuntos
NF-kappa B , Sepse , Animais , Combinação de Medicamentos , Medicamentos de Ervas Chinesas , Camundongos , NF-kappa B/metabolismo , Ocludina , Solução Salina , Sepse/tratamento farmacológico , Fator de Necrose Tumoral alfa/metabolismo
18.
PLoS One ; 16(12): e0261093, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34882730

RESUMO

With the construction and development of ultra-high voltage (UHV) power grids, large-scale, long-distance power transmission has become common. A failure of the connecting line between the sending-end power grid and the receiving-end power grid will cause a large-scale power shortage and a frequency drop in the receiving-end power grid, which can result in the frequency collapse. Presently, under-frequency load shedding (UFLS) is adopted for solving the frequency control problem in emergency under-frequency conditions, which can easily cause large load losses. In this context, a frequency coordination optimal control strategy is proposed, which combines the mode transition of pumped storage units with UFLS to deal with emergency under-frequency problems. First, a mathematical model of the frequency dynamic response is established, which combines the mode transition of pumped storage units with UFLS based on a single-machine equivalent model. Then, an optimal model of the minimal area of the power system's operation frequency trajectory is introduced, yielding the optimal frequency trajectory, and is used for obtaining the action frequency of the joint control strategy. A simulated annealing algorithm based on the perturbation analysis is proposed for solving the optimal model, and the optimal action frequency is obtained that satisfies the transient frequency offset safety constraint of the power system. Thus, the joint optimal control of the mode transition of the pumped storage units and UFLS is realized. Finally, the EPRI-36 bus system and China's actual power grid are considered, for demonstrating the efficiency of the proposed strategy.


Assuntos
Algoritmos , Simulação por Computador , Fontes de Energia Elétrica/normas , Eletricidade , Modelos Teóricos , Humanos
19.
Transl Vis Sci Technol ; 10(9): 13, 2021 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-34388238

RESUMO

Purpose: To investigate crystalline lens tilt and decentration with respect to the corneal vertex (CV) using swept-source optical coherence tomography (SS-OCT) combined with three-dimensional (3D) reconstruction. Methods: Thirty consecutive patients with cataract (30 right eyes) were included in this prospective, observational, pilot case series study. SS-OCT anterior segment images and 3D reconstructions were used for data analysis. Results: The mean distance between the central points of crystalline lens plane and limbus plane was approximately 0.33 ± 0.18 mm. The distance of the center of the limbus plane relative to the CV was approximately 0.31 ± 0.14 mm, which approximated the distance of the center of the crystalline lens plane relative to the CV at 0.33 ± 0.20 mm (P = 0.354). However, the centers of the limbus and crystalline planes were not in the same quadrant in 80% of eyes (24/30). Moreover, the crystalline lens tilted by approximately 4.16° ± 1.97° relative to the CV. Conclusions: The center of the limbus plane was not consistent with that of the crystalline lens plane. The tilt and decentration of the crystalline lens were natural phenomena. Translational Relevance: The SS-OCT technology combined with 3D reconstruction was useful for quantifying the tilt and decentration of the crystalline lens. The definition of angle alpha used for premium IOL screening should be updated.


Assuntos
Cristalino , Lentes Intraoculares , Humanos , Imageamento Tridimensional , Cristalino/diagnóstico por imagem , Estudos Prospectivos , Tomografia de Coerência Óptica
20.
Medicine (Baltimore) ; 100(2): e24109, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33466181

RESUMO

ABSTRACT: To introduce a limbus-centered continuous circular capsulorhexis (CCC) marking technique.Compared with traditional capsulotomy diameter mark technique, a self-designed limbus-centered capsulotomy mark (LCM) was used to perform the routine cataract surgery in this observational study. Ten eyes were included in each group. The area outer/inner 5.5-mm CCC ring, the furthest/nearest distance from the capsule margin to the intraocular lens (IOL) margin, the CCC total coverage IOL area were measured and compared between this 2 groups.No significant differences were found for all the comparison parameters between the 2 groups (all P > .05). However, the capsule total coverage area, area inner 5.5-mm ring was lower in the LCM group, which demonstrated advantage of LCM.The limbus-centered capsulotomy diameter mark, as an inexpensive and convenient method, helps to perform limbus-centered capsulorhexis with not only a 360° overlapping capsular edge but also well-centered IOL optics.


Assuntos
Capsulorrexe/métodos , Limbo da Córnea/cirurgia , Redação/normas , China , Humanos , Facoemulsificação/métodos
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