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1.
Mol Plant ; 2020 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-33278597

RESUMO

Low temperature is a major environmental factor limiting plant growth and productivity. Although transient elevation of cytoplasmic calcium has long been recognized as a critical signal for plant cold tolerance, the calcium channels responsible for this process have remained largely elusive. Here, we reported that OsCNGC9, a cyclic nucleotide-gated channel, positively regulates chilling tolerance by mediating cytoplasmic calcium elevation in rice (Oryza sativa). We showed that the loss-of-function mutant of OsCNGC9 is defective in cold-induced calcium influx and more sensitive to prolonged cold treatment while OsCNGC9 overexpression confers enhanced cold tolerance. Mechanistically, we showed that in response to chilling stress, OsSAPK8, a homolog of Arabidopsis thaliana OST1, phosphorylates and activates OsCNGC9 to trigger Ca2+ influx. In addition, transcription of OsCNGC9 is activated by a rice dehydration responsive element binding transcription factor, OsDREB1A. Together, our results suggested that OsCNGC9 enhances chilling tolerance in rice through regulating cold-induced calcium influx and cytoplasmic calcium elevation.

2.
Zhonghua Nan Ke Xue ; 26(2): 128-133, 2020 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-33346415

RESUMO

Objective: To investigate the expression of phosphoribosyl pyrophosphate synthase 2 (PRPS2) in the human testis and its clinical significance. METHODS: Using quantitative real-time PCR (qRT-PCR) and immunohistochemistry, we detected the expression of PRPS2 mRNA in the testis tissue of the men with normal spermatogenesis or mile, moderate or severe hypospermatogenesis (HS) and that of the PRPS2 protein in the testicular biopsy tissue of 67 adult males. Then, we analyzed the relationship of the PRPS2 expressions with the testicular histological types and clinical parameters of the subjects. RESULTS: The expression of PRPS2 mRNA in the testis tissue was significantly higher in the normal spermatogenesis group than in the moderate and severe HS groups (P < 0.01). The positive expression of the PRPS2 protein was 70.0% in the normal spermatogenesis group, 66.7% in the mild HS group, 50.0% in the moderate HS group and 23.8% in the severe HS group, significantly higher in the normal spermatogenesis and mild HS groups than in the moderate and severe HS groups (P < 0.01). No significant correlation, however, was observed between the PRPS2 expression and clinical parameters of the subjects (P > 0.05). CONCLUSIONS: PRPS2 is lowly expressed in the testis tissue of the men with hypospermatogenesis and its expression level may help the diagnosis of male infertility and the prediction of the spermatogenic function of the testis.


Assuntos
Infertilidade Masculina/genética , Oligospermia/genética , Ribose-Fosfato Pirofosfoquinase/genética , Testículo/enzimologia , Adulto , Humanos , Masculino , Espermatogênese
3.
Plant Dis ; 104(10): 2563-2570, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32762501

RESUMO

Rhizoctonia solani is a widely distributed soilborne plant pathogen, and can cause significant economic losses to crop production. In chemical controls, SYP-14288 is highly effective against plant pathogens, including R. solani. To examine the sensitivity to SYP-14288, 112 R. solani isolates were collected from infected rice plants. An established baseline sensitivity showed that values of effective concentration for 50% growth inhibition (EC50) ranged from 0.0003 to 0.0138 µg/ml, with an average of 0.0055 ± 0.0030 µg/ml. The frequency distribution of the EC50 was unimodal and the range of variation factor (the ratio of maximal over minimal EC50) was 46.03, indicating that all wild-type strains were sensitive to SYP-14288. To examine the risk of fungicide resistance, 20 SYP-14288-resistant mutants were generated on agar plates amended with SYP-14288. Eighteen mutants remained resistant after 10 transfers, and their fitness was significantly different from the parental strain. All of the mutants grew more slowly but showed high virulence to rice plants, though lower than the parental strain. A cross-resistance assay demonstrated that there was a positive correlation between SYP-14288 and fungicides having or not having the same mode of action with SYP-14288, including fluazinam, fentin chloride, fludioxonil, difenoconazole, cyazofamid, chlorothalonil, and 2,4-dinitrophen. This result showed a multidrug resistance induced by SYP-14288, which could be a concern in increasing the spectrum of resistance in R. solani to commonly used fungicides.


Assuntos
Fungicidas Industriais/farmacologia , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Doenças das Plantas , Rhizoctonia/efeitos dos fármacos
4.
Transl Androl Urol ; 9(3): 1244-1251, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32676407

RESUMO

Background: The treatment of ketamine-induced bladder contractures remains poorly studied. We therefore evaluated the efficacy of cystectasia with a sodium hyaluronate balanced solution in this kind of bladder contracture. Methods: Eighteen patients presenting with ketamine-induced bladder contracture between July 2010 and February 2018 were selected and analysed. Ketamine was discontinued in all patients, who were then treated with weekly cystectasia (0.09% sodium hyaluronate balanced solution) 3 times. The volume of the first perfusion was twice the preoperatively measured bladder capacity, and the volume of the subsequent two perfusions was increased by 100 mL each time. The Pelvic Pain and Urgency/Frequency (PUF) symptom score, O'Leary-Sant Interstitial Cystitis (IC) Symptom Index (ICSI), IC Problem Index (ICPI), Quality of Life (QOL) score, and bladder capacity were recorded before surgery and 3 and 12 months after the 3rd expansion. Results: No significant complications were observed during the 3 expansions. Fourteen patients completed the full follow-up schedule. Preoperatively and at the 3- and 12-month follow-up evaluations performed after the 3rd expansion, the PUF symptom scores were 20.4±3.6, 11.5±3.1, and 13.2±3.3, respectively; the mean ICSI was 13.6±2.8, 7.7±2.3, and 8.2±2.5, respectively; the mean ICPI was 10.6±2.6, 7.3±2.1, and 7.7±2.5, respectively; and the mean QOL scores were 6.0±0, 2.1±0.5, and 2.7±0.8, respectively; and the mean bladder catheter volume was 83±27, 234±56, and 228±52 mL, respectively. There were significant differences between all preoperative and postoperative values. Conclusions: Cystectasia with a sodium hyaluronate balanced solution is an effective treatment modality for ketamine-induced bladder contracture.

5.
Colloids Surf B Biointerfaces ; 193: 111022, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32416517

RESUMO

In this paper, the multi-responsive core-shell microgels were prepared for constructing a double-locked drug delivery system. The pH- sensitive poly(2-(diisopropylamino ethylmethacry-late)-block-poly(ethyleneimine) diblock copolymers (PDPA-b-PEI) were synthesized and used to prepare micelles through their self-assembly in neutral solution. Redox-responsive gel shells were formed by Michael addition of primary amine group of branched PEI using disulfide as a cross-linker, which was specifically cleaved by glutathione (GSH). Anticancer drug doxorubicin DOX and perfluorohexane (PFH) could be encapsulated in the core of microgel. The DOX was released sustainably only under the condition of pH and GSH were both right. For example, under neutral condition with GSH, DOX could not release swimmingly due to the core of microgels was in hydrophobic state and wrapped the DOX firmly, although the gel shells were collapsed by GSH. When exposed to ultrasound, the drug released abruptly and achieved a complete release instantly. Moreover, it was found that the structure of the microgels was not destroyed after the ultrasound stimulus but had undergone an expansion-recovery process. Finally, it was demonstrated that the microgel had a "double security" effect, ensuring the low drug leakage during the normal blood circulation and efficient drug release under the pH/redox/ultrasound stimulus. The multi-responsive microgels designed here, which combines the usage of both endogenous and exogenous stimuli, has the advantages of low side-effect, high spatiotemporal controllability and complete release.

6.
ACS Omega ; 5(8): 3878-3888, 2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-32149214

RESUMO

The quantitative structure-property relationship (QSPR) models for predicting the octane number (ON) of toluene primary reference fuel (TPRF; blends of n-heptane, isooctane, and toluene) was investigated. The electrotopological state (E-state) index of TPRF components was computed and weight-summed to generate the quantitative descriptor of TPRF samples. The partial least squares (PLS) technique was used to build up the regression model between the ON and weight-summed E-state index of the investigated samples. The QSPR models for the research octane number (RON) and motor octane number (MON) of TPRF were built. The prediction performance of the obtained PLS models was assessed by the external test set validation and leave-one-out cross-validation. The validation results demonstrate that the proposed PLS models are feasible for predicting the ON, both RON and MON, of TPRF. In addition, several other QSPR models for the ON of TPRF were developed by employing the stepwise regression and Scheffé polynomials methods, and the prediction performance of these models were compared with that of the PLS models. The comparison result shows that the proposed PLS models are slightly better than multiple linear regression models and Scheffé models. It is demonstrated that the combination of the E-state index and PLS is an easy-to-use and promising method for studying and forecasting the ON of TPRF.

7.
Andrologia ; 52(1): e13474, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31710394

RESUMO

Ubiquitin conjugating enzyme (E2) is crucial for mediating N-terminal ubiquitination. Recent study reports that UBE2W is involved in male infertility. However, the correlation between UBE2W expression and hypospermatogenesis is unclear. The present study is to explore the biological role of UBE2W and its association with hypospermatogenesis. Results showed that the sexpression levels of UBE2W in mouse testes were gradually elevated from 2 to 10 weeks, while were significantly deceased in the testes with hypospermatogenesis. When UBE2W expression was successfully down-regulated in spermatogenic cells, the rate of apoptosis was significantly increased and the P53/Bcl-2/caspase 6/caspase 9 signal pathways were activated. Thus, these data indicate that UBE2W down-regulation promotes cell apoptosis and correlates with hypospermatogenesis, which may be helpful for the diagnosis of male infertility.


Assuntos
Azoospermia/patologia , Espermatogênese/fisiologia , Testículo/patologia , Enzimas de Conjugação de Ubiquitina/metabolismo , Animais , Apoptose , Azoospermia/induzido quimicamente , Azoospermia/fisiopatologia , Bussulfano/toxicidade , Linhagem Celular , Dimetil Sulfóxido/toxicidade , Modelos Animais de Doenças , Regulação para Baixo , Humanos , Masculino , Camundongos , RNA Interferente Pequeno/metabolismo , Espermatócitos , Espermatogônias , Enzimas de Conjugação de Ubiquitina/genética
8.
Asian J Androl ; 22(5): 493-499, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31736475

RESUMO

Phosphoribosyl-pyrophosphate synthetase 2 (PRPS2) is a rate-limiting enzyme and plays an important role in purine and pyrimidine nucleotide synthesis. Recent studies report that PRPS2 is involved in male infertility. However, the role of PRPS2 in hypospermatogenesis is unknown. In this study, the relationship of PRPS2 with hypospermatogenesis and spermatogenic cell apoptosis was investigated. The results showed that PRPS2 depletion increased the number of apoptotic spermatogenic cells in vitro. PRPS2 was downregulated in a mouse model of hypospermatogenesis. When PRPS2 expression was knocked down in mouse testes, hypospermatogenesis and accelerated apoptosis of spermatogenic cells were noted. E2F transcription factor 1 (E2F1) was confirmed as the target gene of PRPS2 and played a key role in cell apoptosis by regulating the P53/Bcl-xl/Bcl-2/Caspase 6/Caspase 9 apoptosis pathway. Therefore, these data indicate that PRPS2 depletion contributes to the apoptosis of spermatogenic cells and is associated with hypospermatogenesis, which may be helpful for the diagnosis of male infertility.

9.
Sensors (Basel) ; 19(22)2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31726674

RESUMO

Circular synthetic aperture radar (CSAR) has a 360° observation capability on the central observation scenario. A typical way to process CSAR imaging is to cut data into small sub-apertures because most targets are only coherent at a very small observation angle. There are many sub-aperture imaging methods after development in recent years. The back-projection algorithm is widely used because it is simple and can be applied to an arbitrary trajectory. Because of the limitation of the Nyquist sampling frequency and influence of the antenna sidelobe, azimuth ambiguity is a phenomenon that may occur in the radar imaging process. The existing researches typically choose the back-projection (BP) imaging area according to the SAR platform flight path and the antenna beam width. The limitation of the CSAR imaging area and its azimuth ambiguity region are rarely analyzed theoretically. This paper focus on the sub-aperture imaging of CSAR, based on the BP algorithm, which derives the relationship of azimuth ambiguity with CSAR parameters such as the pause repeat frequency (PRF), slant range angle, velocity of radar platform, etc. This paper proposes an equation for the calculation of the azimuth ambiguity region and analyzes the limitations, which provides theoretical support for CSAR parameter design, imaging area selection, and azimuth ambiguity analysis.

10.
Cancer Manag Res ; 11: 3021-3027, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31118771

RESUMO

Objective: Recently, ribosome binding protein 1 (RRBP1) is reported to be involved in tumorigenesis. However, the expression and clinical significance of RRBP1 in prostate cancer (PCa) remains unknown. This study is aimed to investigate the expression and clinical significance of RRBP1 in PCa. Materials and methods: RRBP1 expression was firstly detected in 6 cases of PCa and matched adjacent non-cancerous prostate tissues by reverse transcription-quantitative PCR (RT-qPCR) and Western blot. Then, RRBP1 expression was further detected in 127 cases of PCa and 40 cases of non-cancerous prostate tissues by immunohistochemistry (IHC). The relationship of RRBP1 with clinical-pathological characters and patients' prognosis was analyzed in PCa. Results: RT-qPCR and Western blot analysis showed that RRBP1 expression levels in PCa tissues were significantly higher compared with those in matched adjacent non-cancerous prostate tissues. IHC results shown that the high-expression rate of RRBP1 in PCa was 69.3%, which was significantly greater than those in non-cancerous prostate tissues (15.0%, P<0.001). RRBP1 expression was significantly associated with T stage, lymph node metastasis, PSA and Gleason score in PCa. Survival analysis indicated that patients with RRBP1 low-expression presented longer survival time compared with those with RRBP1 high-expression. Moreover, RRBP1 as well as T stage, lymph node metastasis and Gleason score could serve as independent prognostic factors in PCa. Conclusion: RRBP1 is highly expressed in PCa and correlates with prognosis, which may serve as a potential biomarker in PCa.

11.
Biomed Res Int ; 2019: 9175234, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31016204

RESUMO

Objective: We aimed to evaluate the efficacy of anterior approach microscopic surgery for patients with the pincer mechanism in cervical spondylotic myelopathy. Methods: The clinical data of pincer cervical spondylotic myelopathy that received anterior cervical decompression and fusion in our hospital from Aug 2014 to Dec 2017 were analyzed retrospectively, including 12 males and 9 females, with an average age of 64.3 years (range 46-81 years). Occupying rate, anterior occupying rate, and posterior occupying rate were measured on pre- and postoperative mid-sagittal MRIs. Pre- and postoperative Japanese Orthopedic Association (JOA) scores, intervertebral space height, and C2 to C7 Cobb's angle were analyzed. Result: Duration of follow-up was six months. The pre- and postoperative anterior occupying rate were averagely 38.6±8.5% and 12.9±5.5%, respectively, the posterior occupying rates were averagely 27.4±7.2% and 13.1±6.6%, respectively, and Cobb's angle changed from 15.3±8.0° to 22.7±7.9°. The intervertebral space height increased from 4.6±0.4mm to 6.5±0.4mm. JOA scores improved significantly by 59.4±34.0% at six months after surgery. Conclusion: Decompression by anterior microscopic surgery can increase spinal canal volume directly, recover intervertebral space height, and resize Cobb's angle, but decrease the posterior compression by ligament Flava indirectly. Anterior decompression under the microscope may provide an alternative surgical option for partial patients with the pincer mechanism in cervical spondylotic myelopathy.


Assuntos
Vértebras Cervicais/cirurgia , Doenças da Medula Espinal/cirurgia , Espondilose/cirurgia , Idoso , Idoso de 80 Anos ou mais , Descompressão Cirúrgica/métodos , Feminino , Humanos , Ligamento Amarelo/cirurgia , Masculino , Microscopia/métodos , Pessoa de Meia-Idade , Procedimentos Neurocirúrgicos/métodos , Radiografia/métodos , Radiologia/métodos , Fusão Vertebral/métodos , Resultado do Tratamento
12.
Langmuir ; 35(15): 5213-5220, 2019 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-30883134

RESUMO

To improve the controllability of drug release from liposome, a series of pH- and photosensitive block copolymers C7H15-AZO- b-PDPAn- b-mPEG were designed and served as an on-off switch in the liposome bilayer. The functional properties of liposomes were studied by dynamic light scattering, fluorophotometry, UV-vis spectroscopy, and fluorescence spectrophotometry. The liposomes with or without copolymer were relatively uniform in size. Their membrane stability was improved obviously after inserting copolymer under pH 7.4, but it decreased in an acidic environment and caused a large amount of drug release. Meanwhile, UV irradiation could also result in more drug release because of the photoisomerization of the azobenzene (AZO) group. Furthermore, intermittent drug-release experiments showed that the PDPA blocks could reversibly get in and out of the liposome bilayer and ultimately realized the complete drug release. All results suggested that the designed copolymers could be inserted into liposome bilayer through self-assembly and could act as a switch for controllable drug release.


Assuntos
Bicamadas Lipídicas/química , Lipossomos/química , Compostos Azo/química , Liberação Controlada de Fármacos , Concentração de Íons de Hidrogênio
13.
R Soc Open Sci ; 6(12): 190813, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31903200

RESUMO

At present, many modification methods have been proposed to improve the performance of recycled aggregate concrete (RAC). In this study, tests on the compressive strength and damping properties of modified RAC with the addition of different proportions of recycled coarse aggregate (RCA) (0, 50, 100%), rubber powder (10, 15, 20%), steel fibre (5, 7.5, 10%) and fly ash (15, 20, 5%) are carried out. To elucidate the effect of the modification method on the interfacial transition zone (ITZ) performance of RAC, model ITZ specimens are used for push-out tests. The results show that when the replacement rate of RCA reaches 100%, the loss factor of the RAC is 6.0% higher than that of natural aggregate concrete; however, the compressive strength of the RAC decreases by 22.6%. With the addition of 20% rubber powder, the damping capacity of the modified RAC increases by 213.7%, while the compressive strength of the modified RAC decreases by 47.5%. However, with the addition of steel fibre and fly ash, both the compressive strength and loss factor of the RAC specimens increase. With a steel fibre content of 10 wt%, the compressive strength and loss factor of the RAC increase by 21.9% and 15.2%, respectively. With a fly ash content of 25 wt%, the compressive strength and loss factor of the RAC increase by 8.6% and 6.9%, respectively. This demonstrates that steel fibre and fly ash are effective in improving both the damping properties and compressive strength of RAC, and steel fibre is more effective than fly ash. Two methods were used for modification of the RAC: reinforcing the RCA through impregnation with a 0.5% polyvinyl alcohol (PVA) emulsion and nano-SiO2 solution, and strengthening the RAC integrally through the addition of fly ash as an admixture. Both of these techniques can improve the ITZ bond strength between the RAC and new mortar. Replacing 10% of the cement with fly ash in the new mortar is shown to be the best method to improve the ITZ strength.

14.
Chem Commun (Camb) ; 54(96): 13567-13570, 2018 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-30444239

RESUMO

The practical application of high energy lithium-sulfur batteries is still limited by unstable lithium anodes and the shuttle effect of polysulfides. Herein, a gel-like electrolyte induced by fumed alumina is proposed for dendrite-free Li deposition, lower over-potential and better cycle stability. Li-S@pPAN cells with the proposed electrolyte exhibit outstanding cycle stability and rate performance with capacity retentions of 95.1% after 300 cycles and 76.5% at 10C against 1C, respectively.

15.
Appl Bionics Biomech ; 2018: 8901067, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30344641

RESUMO

The biplane counter-flapping wing is a special type of wing flapping which is inspired from the fish and insect in nature. The propulsive performance is one of the most important considerations for this kind of flapping wing. This paper is aimed at providing a systematic synthesis on the propulsive characteristics of two flapping wings at biplane configuration based on the numerical analysis approach. Firstly, parameters of this special flapping wing are presented. Secondly, the numerical method for simultaneously solving the incompressible flow and counter-flapping motion of the wing is illustrated, and the method is then validated. Thirdly, the effects of phase angle and mean wing spacing on the propulsive characteristics of the biplane counter-flapping wing are analyzed. Finally, the quantification effects of the phase angle and mean wing spacing on the propulsive characteristics of the biplane counter-flapping wing can be obtained. The analysis results in this study will provide useful guidelines to design an effectively propulsive system applying for the flapping micro air or underwater vehicle.

16.
Oncol Lett ; 16(4): 5160-5166, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30250582

RESUMO

Long non-coding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) has been reported to be overexpressed in prostate cancer cells and associated with tumorigenesis in various types of cancer. However, the biological function of lncRNA PVT1 remains largely unknown. The aim of the present study was to investigate the effect of lncRNA PVT1 expression on the proliferation and migration of prostate cancer cells. Stably transfected prostate cancer cells with downregulated expression of lncRNA PVT1 were constructed by an efficient siRNA fragment, followed by confirmation by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Proliferation was assessed using CCK-8, colony formation and xenograft assays, and cell migration was evaluated using a wound healing assay. The PathScan® Intracellular Signaling Array kit was utilized to explore the underlying molecular mechanisms of lncRNA PVT1 expression in prostate cancer cells. RT-qPCR results confirmed that the lncRNA PVT1 expression level was successfully knocked down in prostate cancer cells. When lncRNA PVT1 expression was downregulated in prostate cancer cells, proliferation and migration were significantly inhibited, compared with the control lncRNA PVT1 group. Furthermore, PVT1 knockdown decreased the phosphorylation of p38 in DU145 cells. Therefore, the present study demonstrated that lncRNA PVT1 downregulation inhibits the proliferation and migration of prostate cancer cells, and is associated with p38 phosphorylation.

17.
Sensors (Basel) ; 18(8)2018 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-30103425

RESUMO

The paper proposes a new method for measuring the azimuth pointing of spaceborne synthetic aperture radar (SAR) antenna beams based on the ground receiver, which can receive and record complex sampling data of the pulse signals transmitted from the spaceborne SAR. The center of the antenna pattern is extracted from the complex sampling data amplitude envelope to obtain the time when the beam main lobe center irradiates the ground receiver, and the range migration information is extracted from the complex sampling data to obtain the time when the satellite is over the top of the ground receiver. The results of Chinese civilian remote sensing GaoFen-3 SAR satellite experiment data processing show that the measurement accuracy of this method is better than 0.002°, which can be applied to the accurate measurement of azimuth pointing of various low Earth orbit (LEO) SAR antenna beams.

18.
Sensors (Basel) ; 18(5)2018 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-29735947

RESUMO

Range ambiguity is one of the factors which affect the SAR image quality. Alternately transmitting up and down chirp modulation pulses is one of the methods used to suppress the range ambiguity. However, the defocusing range ambiguous signal can still hold the stronger backscattering intensity than the mainlobe imaging area in some case, which has a severe impact on visual effects and subsequent applications. In this paper, a novel hybrid range ambiguity suppression method for up and down chirp modulation is proposed. The method can obtain the ambiguity area image and reduce the ambiguity signal power appropriately, by applying pulse compression using a contrary modulation rate and CFAR detecting method. The effectiveness and correctness of the approach is demonstrated by processing the archive images acquired by Chinese Gaofen-3 SAR sensor in full-polarization mode.

19.
Sensors (Basel) ; 18(5)2018 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-29772821

RESUMO

This paper presents an analysis of measurements of the normalized radar cross-(NRCS) in Wave Mode for Chinese C-band Gaofen-3(GF-3) synthetic aperture radar (SAR). Based on 2779 images from GF-3 quad-polarization SAR in Wave Mode and collocated wind vectors from ERA-Interim, this experiment verifies the feasibility of using ocean surface wind fields and VV-polarized NRCS to perform normalized calibration. The method uses well-validated empirical C-band geophysical model function (CMOD4) to estimate the calibration constant for each beam. In addition, the relationship between cross-pol NRCS and wind vectors is discussed. The cross-pol NRCS increases linearly with wind speed and it is obviously modulated by the wind direction when the wind speed is greater than 8 m/s. Furthermore, the properties of the polarization ratio, denoted PR, are also investigated. The PR is dependent on incidence angle and azimuth angle. Two empirical models of the PR are fitted, one as a function of incidence angle only, the other with additional dependence on azimuth angle. Assessments show that the σ VV 0 retrieved from new PR models as well as σ HH 0 is in good agreement with σ VV 0 extracted from SAR images directly.

20.
Sensors (Basel) ; 18(3)2018 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-29534464

RESUMO

The Gaofen-3 (GF-3) data processor was developed as a workstation-based GF-3 synthetic aperture radar (SAR) data processing system. The processor consists of two vital subsystems of the GF-3 ground segment, which are referred to as data ingesting subsystem (DIS) and product generation subsystem (PGS). The primary purpose of DIS is to record and catalogue GF-3 raw data with a transferring format, and PGS is to produce slant range or geocoded imagery from the signal data. This paper presents a brief introduction of the GF-3 data processor, including descriptions of the system architecture, the processing algorithms and its output format.

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