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1.
Eur J Med Chem ; 190: 112113, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32058237

RESUMO

Cobalamin-dependent methionine synthase (MetH) is involved in the process of tumor cell growth and survival. In this study, a novel series of N5-electrophilic substituted tetrahydropteroate analogs without glutamate residue were designed as non-classical antifolates and evaluated for their inhibitory activities against MetH. In addition, the cytotoxicity of target compounds was evaluated in human tumor cell lines. With N5-chloracetyl as the optimum group, further structure research on the benzene substituent and on the 2,4-diamino group was also performed. Compound 6c, with IC50 value of 12.1 µM against MetH and 0.16-6.12 µM against five cancer cells, acted as competitive inhibitor of MetH. Flow cytometry studies indicated that compound 6c arrested HL-60 cells in the G1-phase and then inducted late apoptosis. The molecular docking further explained the structure-activity relationship.

2.
Appl Spectrosc ; : 3702819885647, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31617399

RESUMO

Time-gated picosecond laser-induced breakdown spectroscopy (ps-LIBS) for the determination of local equivalence ratios in atmospheric-pressure adiabatic methane-air flames is demonstrated. Traditional LIBS for equivalence-ratio measurements employ nanosecond (ns)-laser pulses, which generate excessive amounts of continuum, reducing measurement accuracy and precision. Shorter pulse durations reduce the continuum emission by limiting avalanche ionization. Furthermore, by contrast the use of femtosecond lasers, plasma emission via picosecond-laser excitation has high signal-to-noise ratio (S/N), allowing single-shot measurements suitable for equivalence-ratio determination in turbulent reacting flows. We carried out an analysis of the dependence of the plasma emission ratio Hα (656 nm)/NII (568 nm) on laser energy and time-delay for optimization of S/N and minimization of measurement uncertainties in the equivalence ratios. Our finding shows that higher laser energy and shorter time delay reduces measurement uncertainty while maintaining high S/N. In addition to atmospheric-pressure flame studies, we also examine the stability of the ps-LIBS signal in a high-pressure nitrogen cell. The results indicate that the plasma emission and spatial position could be stable, shot-to-shot, at elevated pressure (up to 40 bar) using a lower excitation energy. Our work shows the potential of using ps-duration pulses to improve LIBS-based equivalence-ratio measurements, both in atmospheric and high-pressure combustion environments.

3.
Artigo em Inglês | MEDLINE | ID: mdl-31603813

RESUMO

Compressive sensing technique allows capturing fast phenomena at much higher frame rate than the camera sensor, by recovering a frame sequence from their encoded combination. However, most conventional compressive video sensing methods limit the achieved frame rate improvement to tenfold and only support low resolution recovery. Making use of camera's redundant spatial resolution for further frame rate improve, here we report a novel compressive video acquisition technique termed Sinusoidal Sampling Enhanced Compressive Camera (S2EC2) to encode denser frames within a snapshot. Specifically, we decompose the dense frames into groups and apply combinational coding: random codes within each group for compressive acquisition; group specific sinusoidal codes to multiplex different groups onto the high resolution sensor. The sinusoidal codes designed for these groups would shift their frequency components by different offsets in the Fourier domain and staggered the dominant frequencies of the coded measurements of these groups. Correspondingly, the reconstruction successfully separate coded measurements of different groups and recovers frames within each group. Besides, we also solve the implementation problem of insufficient gray scale spatial light modulation speed, and build a prototype achieving 2000 fps reconstruction with a 15.6 fps camera (the actual compression ratio is 0.009). The extensive experiments validate the proposed approach.

4.
Eur J Med Chem ; 183: 111679, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31541870

RESUMO

Anti-tubulin polymerization agents can disrupt tumor-vascular to exhibit anti-cancer potency. In this study, a series of substituted (2-(phenylamino)thieno[3,2-d]pyrimidin-4-yl)(3,4,5-trimethoxyphenyl)methanone analogues were designed and synthesized as anti-tubulin polymerization agents that interact with colchicine binding site. The anti-proliferative assay indicated that most of the target compounds displayed moderate to high potencies towards five tumor cell lines. The structure-activity relationship of these analogues was summarized. The most potent compound 14 was selected to assay its inhibition on the tubulin polymerization. 14 displayed potent inhibition against tubulin polymerization with an IC50 value of 4.1 ±â€¯0.1 µM. The colchicine competition assay demonstrated that 14 inhibited tubulin polymerization by binding to the colchicine-binding site of tubulin. The molecular modeling study elucidated the binding mode of 14 in the colchicine binding site. The result of confocal immunofluorescent study proved that 14 can quickly disrupt the microtubules of Hela cells in a concentration dependent manner. Some experiments at cellular level were conducted to investigate the effects of 14 on cellular morphology, cell colony formation, cell cycle distribution, cell apoptosis and mitochondrial changes. The results demonstrated that 14 is a potent anti-tubulin agent with strong concentration dependent effect of inhibition of colony formation, induction of G2/M arrest and induction of apoptosis through mitochondrial pathway.


Assuntos
Antineoplásicos/síntese química , Pirimidinas/síntese química , Moduladores de Tubulina/síntese química , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Sítios de Ligação , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Colchicina/metabolismo , Desenho de Drogas , Humanos , Modelos Moleculares , Estrutura Molecular , Ligação Proteica , Pirimidinas/farmacologia , Relação Estrutura-Atividade , Moduladores de Tubulina/farmacologia
5.
Med Sci Monit ; 25: 4705-4715, 2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31235682

RESUMO

BACKGROUND The aim of this study was to evaluate lysophosphatidic acid receptor-2 (LPA2) and Krüppel-like factor 5 (KLF5) protein expression in gastric adenocarcinoma and their correlation with patient clinicopathological characteristics and prognosis. MATERIAL AND METHODS Fifty-one gastric adenocarcinoma tissue samples, 21 gastric intraepithelial neoplasia (GIN) samples, and 13 normal gastric tissue samples were collected to test for LPA2 and KLF5 expression by tissue microarray and immunohistochemistry assay. LPA2 and KLF5 positive expression rate between gastric adenocarcinoma, GIN, and normal gastric tissue were compared. The relationship between LPA2 expression, KLF5 expression, and patients' clinicopathological characteristics and prognosis were evaluated. RESULTS The positive expression rate of LPA2 and KLF5 were statistical different in gastric adenocarcinoma, GIN, and normal gastric tissue (P<0.05). LPA2 positive expression was associated with tumor invasion depth, Lauren type, vascular invasion, local lymph node metastasis, and clinical stage (P<0.05). There was no correlation between LPA2 expression (hazard ratio [HR]=1.84, 95% confidence interval [CI]: 0.89-3.80, P>0.05), KLF5 expression (HR=1.13, 95% CI: 0.53-2.36, P>0.05), and gastric cancer patients' overall survival. CONCLUSIONS LPA2 and KLF5 protein expressions were differently expressed in gastric adenocarcinoma, GIN, and normal gastric tissue, and differences were correlated with patients' clinical characteristic. However, LPA2 and KLF5 expressions were not correlated with the patients' prognosis.


Assuntos
Fatores de Transcrição Kruppel-Like/metabolismo , Receptores de Ácidos Lisofosfatídicos/metabolismo , Neoplasias Gástricas/metabolismo , Adenocarcinoma/metabolismo , Adenocarcinoma/patologia , Adulto , Idoso , Feminino , Humanos , Imuno-Histoquímica , Fatores de Transcrição Kruppel-Like/biossíntese , Fatores de Transcrição Kruppel-Like/genética , Masculino , Pessoa de Meia-Idade , Prognóstico , Modelos de Riscos Proporcionais , Receptores de Ácidos Lisofosfatídicos/biossíntese , Receptores de Ácidos Lisofosfatídicos/genética , Neoplasias Gástricas/patologia
6.
Appl Opt ; 58(16): 4326-4331, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31251242

RESUMO

Simultaneous measurements of refractive index, surface tension, and evaporation rate in pendant droplets have been conducted in water, ethanol, n-heptane, diesel, and Jet A fuel in a temperature range of 20°C-50°C at atmospheric pressure. The dispersion of the refractive indices has been determined by means of rainbow refractometry. The surface tensions have been measured based on the pendant droplet shape analysis. The Young-Laplace equation and the numerical model have been applied to precisely obtain surface tension from the balance between the droplet distortion of gravity and restoring the force of surface tension. The evaporation of the fuels has also been studied with pure droplets of a few millimeters in diameter in a temperature-controlled environment. The shadowgraph technique has been performed for the precise measurement of the droplet size change with a long-working-distance objective (10× magnification). The evaporation rate has been determined by the temporal rate of droplet diameter change extracted from the subsequent images. The experimental data in this work is compared with the previous work to validate the accuracy and estimate uncertainty. Furthermore, the simultaneous multi-property measurement of Jet A fuel (POSF 4658) has been conducted. These properties of the aviation fuel can be used in computation and modeling to further improve the knowledge of jet injection (atomization and evaporation) and practical combustion processes.

7.
Oncol Lett ; 17(6): 5536-5544, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31186775

RESUMO

Head and neck squamous cell carcinoma (HNSC) is one of most common types of cancer worldwide, and mRNAs and long non-coding RNAs (lncRNAs) have been identified as prognostic biomarkers in HNSC. In the present study, using gene expression datasets from multiple platforms, survival-associated genes in HNSC were identified. Subsequently, a combination of 17 genes (14 mRNAs and 3 lncRNA) was optimized using random forest variable hunting and a risk score model for HNSC prognosis was developed using a cohort from The Cancer Genome Atlas. Patients with high-risk scores tend to have earlier disease recurrence and lower survival rates, compared with those with low-risk scores. This observation was further validated in three independent datasets (GSE41613, GSE10300 and E-MTAB-302). Association analysis revealed that the risk score is independent of other clinicopathological observations. On the basis of the results depicted in the nomogram, the risk score performs better in 3-year survival rate prediction than other clinical observations. In summary, the lncRNA-mRNA signature-based risk score successfully predicts the survival of HNSC and serves as an indicator of prognosis.

8.
Materials (Basel) ; 12(10)2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-31121809

RESUMO

In this research, a new low refractive index ferrofluid is proposed by coating magnetic nanoparticles with a layer of silver, applying the method of modified chemical co-precipitation. This preparation method is green and environmentally friendly without toxic gases being released. Coated nanoparticles are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), and vibration sample magnetometery (VSM). These characterizations show that the silver nanoparticles grow on the surface of magnetic nanoparticles in this new ferrofluid. The hysteresis loop of this new ferrofluid demonstrates that it maintains superparamagnetic properties. A new method of refractive index measurement is applied in this research by employing a long-period grating (LPG) optical fiber sensor. The change value in the refractive index per unit concentration reduces by 16.46% compared to the conventional ferrofluid.

9.
Appl Opt ; 58(10): C30-C35, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31045028

RESUMO

Two-dimensional (2D) Rayleigh scattering (RS) imaging at an ultrahigh repetition rate of 100 kHz is demonstrated in non-reacting flows employing a high-energy burst-mode laser system. Image sequences of flow mixture fraction were directly derived from high-speed RS images. Additionally, a 2D instantaneous flow velocity field at 100 kHz was obtained through optical-flow-based analysis of the RS images. In further analysis of both the mixture fraction and flow velocity field, the result for the centerline mixture fraction agreed well with the scaling law. The demonstrated high-speed RS technique in conjunction with optical-flow-based analysis provides non-intrusive, simultaneous measurements of the flow mixing and velocity field, extending the measurement capability of the RS technique to high-speed non-reacting and reacting flows.

10.
Appl Opt ; 58(10): C61-C67, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31045032

RESUMO

The fuel/air ratio (FAR) in a methane-air Hencken flame at pressures of 1-5 bar is measured using the chemiluminescence-based method. Emission spectra are used to investigate the effects of pressure on the OH* (308 nm), CH* (430 nm), and C2* (500 nm) emissions and the effect on equivalence ratio determination from the ratios of these emission peaks. Both OH*/CH* and C2*/CH* ratios are linear to FAR at atmospheric pressure. At elevated pressures, C2*/CH* remains roughly linear to FAR, while OH*/CH* becomes highly nonlinear. There are significant spectral contributions from continuum radiation at higher pressures, likely due to increasing soot production. Therefore, while it is a truly passive and nonintrusive diagnostic method, the use of chemiluminescence for FAR determination at high pressures could be limited. Possible improvements to the measurement setup and future studies are discussed.

11.
PLoS One ; 14(5): e0217349, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31141561

RESUMO

With the prosperity of machine learning and cloud computing, meaningful information can be mined from mass electronic medical data which help physicians make proper disease diagnosis for patients. However, using medical data and disease information of patients frequently raise privacy concerns. In this paper, based on single-layer perceptron, we propose a scheme of privacy-preserving clinical decision with cloud support (PPCD), which securely conducts disease model training and prediction for the patient. Each party learns nothing about the other's private information. In PPCD, a lightweight secure multiplication is presented and introduced to improve the model training. Security analysis and experimental results on real data confirm the high accuracy of disease prediction achieved by the proposed PPCD without the risk of privacy disclosure.


Assuntos
Confidencialidade/ética , Tomada de Decisões Assistida por Computador , Algoritmos , Computação em Nuvem , Segurança Computacional/tendências , Confidencialidade/normas , Tomada de Decisões , Revelação , Registros Eletrônicos de Saúde , Humanos , Aprendizado de Máquina , Registros Médicos , Privacidade
12.
Eur J Med Chem ; 171: 420-433, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30928712

RESUMO

(E)-3,4-dihydroxystyryl alkyl sulfones, as new analogues of neurodegenerative agents, were designed and synthesized. The biological results demonstrated that most of the target compounds preserved antioxidant and anti-inflammatory potency in scavenging reactive free radicals, protecting neuronal cells against neurotoxins such as H2O2, 6-hydroxydopamine and inhibiting lipopolysaccharide (LPS)-induced over-production of NO. Among these compounds, 6.22 with cyclopentyl propyl exhibited prominent antioxidant activity at low concentration (2.5 µM) in H2O2 model (cell viability = 94.5%). In addition, 6.22 (IC50 = 1.6 µM) displayed better anti-inflammatory activity than that of lead compound 1 (IC50 = 13.4 µM). In view of the outstanding performance of 6.22, the apoptotic rates of H2O2-damaged PC12 cells were detected by Annexin V-FITC/PI assay. 6.22 showed higher potency in inhibition of apoptosis than 1 at low concentration (2.5 µM), consisting with the antioxidant and anti-inflammatory models. Furthermore, with the predicted CNS (+) blood-brain barrier (BBB) permeability (Pe = 6.84 × 10-6 cm s-1), low cytotoxicity and favorable physiochemical properties based on calculation, compound 6.22 can be further developed as a potential multifunctional neuroprotective agent.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Antioxidantes/farmacologia , Barreira Hematoencefálica/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Animais , Anti-Inflamatórios não Esteroides/síntese química , Anti-Inflamatórios não Esteroides/química , Antioxidantes/síntese química , Antioxidantes/química , Apoptose/efeitos dos fármacos , Compostos de Bifenilo/antagonistas & inibidores , Linhagem Celular , Relação Dose-Resposta a Droga , Peróxido de Hidrogênio/farmacologia , Camundongos , Estrutura Molecular , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/síntese química , Fármacos Neuroprotetores/química , Estresse Oxidativo/efeitos dos fármacos , Células PC12 , Permeabilidade/efeitos dos fármacos , Picratos/antagonistas & inibidores , Ratos , Relação Estrutura-Atividade
14.
Toxicol Lett ; 310: 31-38, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30974164

RESUMO

This study focused on the effect of bone marrow mesenchymal stem cells (BMSCs) on the repair of rat liver injury induced by Cr (VI). Twenty-four Wistar rats were randomly divided into the control, model and cell therapy group, with 8 rats in each group. Potassium dichromate solution containing 0, 0.4 and 0.4 mg/kg·bw Cr (VI) was administered 5 times a week for 30 days. At the end of treatment, rats in the cell therapy group were administered 1 × 107 BMSCs. Two weeks later, serum alanine and aspartate aminotransferase levels in the cell therapy group were significantly improved compared with those in the model group, CM-Dil-labeled BMSCs were localized in rat livers. Compared with the model group, in the cell therapy group the number of apoptotic hepatocytes by TUNEL assay, MDA content, the expression of HIF-1α, endoplasmic reticulum (ER) stress-mediated apoptosis-related proteins including Grp78, CHOP, Cleaved-Caspase-12, ATF6, and Bax was significantly lower, and SOD activity, the expression of SIRT1 and Bcl-2 was significantly higher. It is suggested that BMSCs are localized in livers and reduce the toxic effects of Cr (VI) on the liver, and the possible mechanism may be related to the mechanisms of BMSCs decreasing ER stress-mediated hepatocyte apoptosis via the SIRT1/HIF-1α signaling pathway.


Assuntos
Apoptose/efeitos dos fármacos , Doença Hepática Induzida por Substâncias e Drogas/prevenção & controle , Cromo/toxicidade , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Fígado/efeitos dos fármacos , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/enzimologia , Transdução de Sinais/efeitos dos fármacos , Sirtuína 1/metabolismo , Animais , Comunicação Celular , Diferenciação Celular , Células Cultivadas , Doença Hepática Induzida por Substâncias e Drogas/enzimologia , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Doença Hepática Induzida por Substâncias e Drogas/patologia , Fígado/enzimologia , Fígado/patologia , Ratos Wistar
15.
Appl Spectrosc ; 73(6): 591-600, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30990068

RESUMO

This work describes the use of a laser-induced breakdown spectroscopy (LIBS) system to conduct macroscopic elemental mapping of uranium and iron on the exterior surface and interior center cross-section of surrogate nuclear debris for the first time. The results suggest that similar LIBS systems could be packaged for use as an effective instrument for screening samples during collection activities in the field or to conduct process control measurements during the production of debris surrogates. The technique focuses on the mitigation of chemical and physical matrix effects of four uranium atomic emission lines, relatively free of interferences and of good analytical value. At a spatial resolution of 0.5 mm, a material fractionation pattern in the surrogate debris is identified and discussed in terms of constituent melting temperatures and thermal gradients experienced.

16.
Ecotoxicol Environ Saf ; 176: 234-241, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-30939403

RESUMO

The present study aimed to explore the repair effect and mechanism of bone marrow mesenchymal stem cells (BMSCs) transplantation on injured kidneys caused by hexavalent chromium (Cr (VI)). Wistar rats were intraperitoneally injected with 0.4 mg/kg•bw Cr (VI) ion solution. After 30 days, 1 × 107 BMSCs were transplanted into rats. After cell transplantation for 2 weeks, there was no significant difference in the chromium content between the model and BMSCs-therapy group by atomic absorption spectrometry. In BMSCs-therapy group, the renal organ index, the serum levels of blood urea nitrogen (BUN) and creatinine (CRE), malonaldehyde (MDA) content were significantly decreased, superoxide dismutase (SOD) activity was significantly elevated, and the pathological changes were improved compared with the model group. The results of immunohistochemical and western blot assays showed that the expressions of apoptosis-related proteins Bax, Cytochrome c, and Caspase-3, as well as autophagy-associated proteins Beclin 1, PINK1, Parkin, p-Parkin, LC3B, and the MAPK signaling pathway, including the ratio of p-p38 to p38 and p-JNK to JNK were all significantly decreased, Bcl-2 and p62 expressions, and the ratio of p-ERK to ERK were significantly elevated in BMSCs-therapy group compared with the model group. These results suggested that BMSCs repaired Cr (VI)-injured kidney through decreasing mitochondria-mediated apoptosis and mitophagy mediated by downregulating phosphorylation of p38 and JNK, upregulating phosphorylation of ERK.


Assuntos
Apoptose/efeitos dos fármacos , Cromo/toxicidade , Nefropatias/terapia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Transplante de Células-Tronco Mesenquimais , /efeitos dos fármacos , Animais , Autofagia/efeitos dos fármacos , Rim/efeitos dos fármacos , Rim/metabolismo , Rim/patologia , Nefropatias/metabolismo , Nefropatias/patologia , Testes de Função Renal , Masculino , Fosforilação , Ratos , Ratos Wistar
17.
Appl Opt ; 58(8): 1984-1990, 2019 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-30874065

RESUMO

Quantitative femtosecond two-photon laser-induced fluorescence of atomic oxygen was demonstrated in an H2/air flame at pressures up to 10 atm. Femtosecond excitation at 226.1 nm was used to pump the 3pP3J'=0,1,2←←2pP3J''=0,1,2 electronic transition of atomic oxygen. Contributions from multiphoton de-excitation, production of atomic oxygen, and photolytic interferences were investigated and minimized by limiting the laser irradiance to ∼1011 W/cm2. Quantitative agreement was achieved with the theoretical equilibrium mole fraction of atomic oxygen over a wide range of fuel-air ratios and pressures in an H2/air laminar calibration burner.

18.
Opt Express ; 26(20): 25750-25760, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30469671

RESUMO

Laser-induced breakdown spectroscopy (LIBS) evaluates the emission spectra of ions, radicals, and atoms generated from the breakdown of molecules by the incident laser; however, the LIBS signal is unstable at elevated pressures. To understand the cause of the signal instability, we perform simultaneous time-resolved measurements of the electron density and LIBS emission signal for nitrogen (568 nm) and hydrogen (656 nm) at high pressure (up to 11 bars). From correlations between the LIBS signal and electron number density, we find that the uncontrollable generation of excess electrons at high pressure causes high instability in the high-pressure LIBS signal. A possible method using ultrafast lasers is proposed to circumvent the uncontrolled electron generation and improve signal stability at high pressure.

19.
Opt Express ; 26(22): 28441-28452, 2018 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-30470015

RESUMO

The Multiplexed Structured Image Capture (MUSIC) technique is used to demonstrate single-shot multiframe passive imaging, with a nanosecond difference between the resulting images. This technique uses modulation of light from a scene before imaging, in order to encode the target's temporal evolution into spatial frequency shifts, each of which corresponds to a unique time and results in individual and distinct snapshots. The resulting images correspond to different effective imaging gate times, because of the optical path delays. Computer processing of the multiplexed single-shot image recovers the nanosecond-resolution evolution. The MUSIC technique is used to demonstrate imaging of a laser-induced plasma. Simultaneous single-shot measurements of electron numbers by coherent microwave scattering were obtained and showed good agreement with MUSIC characterization. The MUSIC technique demonstrates spatial modulation of images used for passive imaging. This allows multiple frames to be stacked into a single image. This method could also pave the way for real-time imaging and characterization of ultrafast processes and visualization, as well as general tracking of fast objects.

20.
Appl Opt ; 57(20): 5666-5671, 2018 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-30118079

RESUMO

Quantitative, kiloherz-rate measurement of carbon monoxide mole fractions by femtosecond two-photon, laser-induced fluorescence (TP-LIF) was demonstrated in high-pressure, luminous flames over a range of fuel-air ratios. Femtosecond excitation at 230.1 nm was used to pump CO two-photon rovibrational X1Σ+→B1Σ+ transitions in the Hopfield-Birge system and avoid photolytic interferences with excitation irradiance ∼1.7×1010 W/cm2. The effects of excitation wavelength, detection scheme, and potential sources of de-excitation were also assessed to optimize the signal-to-background and signal-to-noise ratios and achieve excellent agreement with theoretically predicted CO mole fractions at low and high pressure.

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