Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 32
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Bioresour Technol ; 302: 122880, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32007855

RESUMO

The denitrification (DN), partial nitrification (PN) and Anammox processes were coupled in an auto-recycling integration device to remove nitrogen from the supernatant of sludge reduction pretreatment. The nitrogen removal performance of the device and the effect of organic matter concentration on the nitrogen transformation were discussed. The results showed that DN, PN and Anammox are well coupled and total nitrogen (TN) removal rate reached 0.85 kg/(m3·d). The pre-DN process can achieve the removal of NO3--N produced by the back-end PN-Anammox process without the need of reflux pump drive. When the influent NH4+-N concentration was approximately 400 mg/L, the effluent TN concentration was less than 20 mg/L. The fluctuation of organic matter led to changes of nitrogen transformation in the system, and the best ratio of influent CODbio/TN was 0.7-0.9. Nitrosomonas and Candidatus Brocadia played important roles in the nitrogen removal process as the main functional microorganisms of PN and Anammox, respectively.

2.
Bioresour Technol ; 301: 122758, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31986373

RESUMO

Cultivating sand-consolidating cyanobacteria using wastewater has unique advantages on both nutrients recycling and ecological restoration by transferring excessive nutrients from wastewaters to desert areas. Although previous study showed that sand-consolidating cyanobacterium well adapted to synthetic domestic wastewater, no study has been carried out on actual wastewater. This study aims to investigate the sand-consolidating cyanobacterial biomass production and nutrients removal by cultivating Scytonema hyalinum in the municipal wastewater under different temperatures. The results showed that biomass accumulation increased with temperature from 20 â„ƒ to 30 â„ƒ, while severely depressed at 35 â„ƒ. More than 81.63% sCOD, 90.64% TDN and 97.08% TDP were removed by day 30 under each temperature except for 35℃. The inoculation of S. hyalinum strongly regulated the native wastewater bacterial community. These results indicated that sand-consolidating cyanobacterium S. hyalinum well adapted to municipal wastewater and temperature had remarkable effects on cyanobacterial biomass accumulation, nutrients removal and wastewater native bacterial community dynamics.


Assuntos
Cianobactérias , Águas Residuárias , Biomassa , Nitrogênio , Nutrientes , Areia , Temperatura Ambiente
3.
Chem Commun (Camb) ; 56(11): 1653-1656, 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-31939470

RESUMO

Distinct annexin V binding behaviours in Ca2+-dependent and Ca2+-independent cases were comparatively investigated using sum frequency generation vibrational spectroscopy. It was discovered that binding affected the molecular arrangement of both membrane leaflets, and the initial Ca2+-independent binding went through a transition with annexin V reorientation to a more stable state upon adding Ca2+.

4.
Bioresour Technol ; 297: 122430, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31761626

RESUMO

The effects on nitrogen removal from landfill leachate were compared between the denitrification (DN) direct coupling in Partial nitrification (PN)-Anammox (DN+(PN-Anammox)) and pre-DN followed by PN-Anammox (DN-PN-Anammox). Both processes can achieve coupling and high nitrogen removal. However, the DN+(PN-Anammox) process was not conducive to the treatment of high-COD wastewater. The total nitrogen removal rate (TNRR) and total nitrogen removal efficiency (TNRE) were stable at 0.31 kg/(m3·d) and 76.3%. When UASB was added to denitrification and transform the process into DN-PN-Anammox, the influent NH4+-N and COD concentrations were increased to 2230 and 2612 mg/L, TNRR and TNRE reached 0.45 kg/(m3·d) and 96.7%, respectively. The DN-PN-Anammox process not only was able to make full use of degradable COD in wastewater to realize the NO3--N removal, but also benefited the growth of autotrophic bacteria. The DN-PN-Anammox reduced the oxygen supply and was more conducive to the treatment of highly-concentrated mature landfill leachate.


Assuntos
Desnitrificação , Poluentes Químicos da Água , Reatores Biológicos , Nitrificação , Nitrogênio , Oxirredução
5.
Sci Total Environ ; 703: 134949, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31740059

RESUMO

Flocs and granules tend to coexist in a single reactor. Granules can improve microbial retention capacity, however, the role of flocs in the CANON reactor remains unclear. The changes in the nitrogen removal performance and microbial communities between flocs-granules hybrid and granule-based systems were studied in this experiment. With a reduction in the flocs ratio (35% → 10%), the nitrogen removal performance deteriorated. The average nitrogen removal efficiency and rate dropped from 81.4% to 67.2% and from 0.225 to 0.174 kg/(m3·d), respectively. The contribution of heterotrophic denitrifying bacteria decreased from 13.5% to 1%, leading to changes in the nitrogen removal pathways between the systems. Furthermore, the activities of anaerobic and aerobic ammonium oxidizing bacteria declined dramatically, which weakened the nitrogen removal performance. Thus, the hybrid system with a flocs ratio near 35% is recommended for use in a CANON reactor.

6.
J Mass Spectrom ; 55(1): e4441, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31840882

RESUMO

Column heating strategy is often applied in nano-high-performance liquid chromatography-mass spectrometer (nanoHPLC-MS) platform for enhancing the analytical efficiency of peptides or proteins. Nonetheless, the influence effects of column heating in peptides or proteins identification still lack of deep understanding. In this study, a systematic comparison of room temperature (RT) and column heating of nanoHPLC was done. Based on the data, under column heating condition, the backpressure of nanoHPLC can be decreased. Due to the increase of resolution, the peak widths of precursor ion were narrowed. As a result, in MS/MS data acquisition part, more time was spared for MS1 detecting and MS2 fragmenting, which eventually resulted in increased identification of peptides and proteins. Moreover, we also proposed the application scope of column heating by evaluating its influence on sample detection. On one hand, column heating significantly increased the identification of membrane proteins due to more efficient elution of highly hydrophobic peptides compared with RT. On the other hand, heating was not suitable for analyzing short or/and hydrophilic peptides with low retention time, which would be eluted out during sample loading process under high temperature and missed by mass spectrometric detection. In conclusion, our study provides a reference for rational application of column heating in proteomics research.

7.
J Proteomics ; 213: 103614, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31846764

RESUMO

Lysine methylation is a widespread protein post-translational modification showing essentialities in versatile cellular process. EZH2, a methyltransferase specifically trimethylates the lysine 27 of histone H3 and its aberrance in several cancers promotes the development of its inhibitors against hematological tumors. In this study, we presented a deep exploration of lysine mono-, di- and trimethylomes in EZH2 wild-type and Y641 mutant lymphoma cell lines. Our results showed that several substrates were modified in different methylation levels. Moreover, these methylated lysine residues could also undergo other types of PTMs. Combined with the differences proved in protein expression, lysine acetylation, lysine ubiquitylation and protein N-termianl acetylation level, our study underlined the substrate specificity of lysine methylation and its crosstalk with other types of PTMs. Totally, our study raised new insights into the global cellular methylation features in hematological cell lines, which provided further inspects into the distribution and function of lysine methylation. SIGNIFICANCE: Our study showed the global landscape of mono-, di- and trimethylomes in the EZH2-aberrant DLBCL cell lines, revealing the molecular characteristics of lysine methylation. Combined with the protein abundance and potential crosstalk among different types of PTMs, our study raised new insights into the global cellular methylation features in hematological tumors and provided further inspects into the distribution and function of lysine methylation.

8.
Nanomaterials (Basel) ; 9(11)2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31766154

RESUMO

The effects of divacancy, including isolated defects and extended line defects (ELD), on the thermal transport properties of graphene nanoribbons (GNRs) are investigated using the Nonequilibrium Green's function method. Different divacancy defects can effectively tune the thermal transport of GNRs and the thermal conductance is significantly reduced. The phonon scattering of a single divacancy is mostly at high frequencies while the phonon scattering at low frequencies is also strong for randomly distributed multiple divacancies. The collective effect of impurity scattering and boundary scattering is discussed, which makes the defect scattering vary with the boundary condition. The effect on thermal transport properties of a divacancy is also shown to be closely related to the cross section of the defect, the internal structure and the bonding strength inside the defect. Both low frequency and high frequency phonons are scattered by 48, d5d7 and t5t7 ELD. However, the 585 ELD has almost no influence on phonon scattering at low frequency region, resulting in the thermal conductance of GNRs with 585 ELD being 50% higher than that of randomly distributed 585 defects. All these results are valuable for the design and manufacture of graphene nanodevices.

9.
Braz J Med Biol Res ; 52(9): e8446, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31482999

RESUMO

Left atrial diameter (LAD) has been considered an independent risk factor for atrial fibrillation (AF) relapse after pulmonary vein isolation (PVI). However, whether LAD or other factors are more predictive of late recurrence in patients with paroxysmal AF remains unclear. We aimed to evaluate the value of pulmonary vein (PV) parameters for predicting AF relapse 1 year after patients underwent cryoablation for paroxysmal AF. Ninety-seven patients with paroxysmal AF who underwent PVI successfully were included. PV parameters were measured through computed tomography scans prior to PVI. A total of 28 patients had recurrence of AF at one-year follow-up. The impact of several variables on recurrence was evaluated in multivariate analyses. LAD and the time from first diagnosis of AF to ablation maintained its significance in predicting the relapse of AF after relevant adjustments in multivariate analysis. When major diameter of right inferior pulmonary vein (RIPV) (net reclassification improvement (NRI) 0.179, CI=0.031-0.326, P<0.05) and cross-sectional area (CSA) of RIPV (NRI: 0.122, CI=0.004-0.240, P<0.05) entered the AF risk model separately, the added predictive capacity was large. The accuracy of the two parameters in predicting recurrence of AF were not inferior (AUC: 0.665 and 0.659, respectively) to echocardiographic LAD (AUC: 0.663). The inclusion of either RIPV major diameter or CSA of RIPV in the model increased the C-index (0.766 and 0.758, respectively). We concluded that major diameter of RIPV had predictive capacity similar to or even better than that of LAD for predicting AF relapse after cryoablation PVI.


Assuntos
Fibrilação Atrial/etiologia , Átrios do Coração/anatomia & histologia , Veias Pulmonares/anatomia & histologia , Idoso , Fibrilação Atrial/cirurgia , Ablação por Cateter/métodos , Criocirurgia/métodos , Feminino , Átrios do Coração/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Veias Pulmonares/diagnóstico por imagem , Recidiva , Fatores de Risco , Sensibilidade e Especificidade , Tomografia Computadorizada por Raios X , Resultado do Tratamento
10.
ACS Omega ; 4(5): 8015-8021, 2019 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-31459890

RESUMO

A remarkable recent advancement has been the successful synthesis of two-dimensional boron monolayers on metal substrates. However, although up to 16 possible bulk allotropes of boron have been reported, none of them possess van der Waals (vdW) layered structures. In this work, starting from the experimentally synthesized monolayer boron sheet (ß12 borophene), we explored the possibility for forming vdW layered bulk boron. We found that two ß12 borophene sheets cannot form a stable vdW bilayer structure, as covalent-like B-B bonds are formed between them because of the peculiar bonding. Interestingly, when the covalently bonded bilayer borophene sheets are stacked on top of each other, three-dimensional (3D) layered structures are constructed via vdW interlayer interactions, rather than covalent. The 3D vdW layered structures were found to be dynamically stable. The interlayer binding energy is about 20 meV/Å2, which is close to the weakly bound graphene layers in graphite (∼16 meV/Å2). Furthermore, the density functional theory predicted electronic band structure testifies that these vdW bulk boron crystals can behave as good conductors. The insights obtained from this work suggest an opportunity to discover new vdW layered structures of bulk boron, which is expected to be crucial to numerous applications ranging from microelectronic devices to energy storage devices.

11.
Langmuir ; 35(35): 11351-11357, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31436095

RESUMO

Here, we report a straightforward approach to fabricate antifogging antireflective dual-function nanostructured coatings, where antireflective nanograsses were etched into antifogging polymer coatings by self-masking reactive ion etching (RIE). The transmittance of coatings increases with the etching time, and the maximum transmittance reaches up to 98.9% in 180 s. The effective refractive index of grass-like nanostructure was calculated to be 1.15 and its optical property was simulated via the finite difference time domain (FDTD) model. The antifogging property of polymer coatings remains unchanged after RIE, which results from the hygroscopicity of polymer matrix. This strategy surpasses traditional design concepts of antifogging polymer coatings by combining excellent antireflective and antifogging properties on the same outermost layer, which demonstrates that it is probable to achieve multifunction on a single layer of a single composition.

12.
Environ Sci Pollut Res Int ; 26(27): 27752-27760, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31338766

RESUMO

In order to explore the research trends and hotspots related to the treatment of heavy metals in wastewater by graphene and its composites, this study collected information on 511 publications from the Science Citation Index-Expanded (SCIE) and conducted a quantitative and visual analysis. The article on the adsorption of heavy metals in wastewater by graphene and its composites first appeared in 2006 and continued to grow since 2011. It broke through 100 articles for the first time in 2016 and the overall trend is on the rise. The 511 articles were published in 185 journals, of which RSC Advances is the most dynamic journal, and Journal of Materials Chemistry A is the most authoritative journal. Asian authors published about 87.14% of papers, and China, Iran, and India played a leading role compared with other countries. The University of Chinese Academy of Sciences is the largest research institution for the adsorption of heavy metals in wastewater by graphene and its composites. Hot keywords are "heavy metal removal," "water sample," "recent advance," "reusable adsorbent," "graphene-based material," and "composite nanosheet." Combined with keywords and cluster analysis, the chemical modification of graphene oxide has become a hot research direction for graphene materials to remove heavy metals from wastewater. Among them, MnFe2O4-graphene composite is a hot spot for graphene modification. In general, HNO3, HCl, and EDTA are desorption reagents for graphene and its composites.


Assuntos
Grafite/análise , Metais Pesados/química , Óxidos/química , Águas Residuárias/análise , Adsorção , China , Índia , Irã (Geográfico) , Publicações , Águas Residuárias/química
13.
Environ Pollut ; 250: 437-446, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31026690

RESUMO

In this study, antibiotic resistance to macrolide-lincosamide-streptogramin B (MLSB) antibiotics in total microbial community in surface water in a coastal urban city was measured using a modified fluorescence in situ hybridization (FISH) technique. This FISH technique quantified the rate of antibiotic resistance to MLSB antibiotics through targeting methylation site of A2058 of 23S rRNAs resulting from expressed erythromycin ribosome methylation (erm) genes. Correlations between the rates of MLSB resistance measured by FISH and macrolide concentrations was stronger than that between the relative abundance of erm genes and macrolide concentrations, especially in residential areas where the main detected antibiotics were macrolides. These results suggest that trace levels of antibiotics in environmental waters, which was as low as 40 ng L-1, may still play important roles in the development and spread of antibiotic resistance. Additionally, methylation as a result of erm gene expression, instead of erm gene abundance, was a better indicator of selective pressure of trace level macrolides. The rates of MLSB resistance varied significantly among land use types, suggesting that anthropogenic activities are important factors to select for erm gene expression in the environment. Microbial community analysis of representative surface water samples showed that relatively high rates of MLSB resistance were observed in Alphaproteobacteria (42%), Acidobacteria (36%), Bacteroidaceae (32%), Chloroflexi (27%), and Betaproteobacteria (20.2%).


Assuntos
Antibacterianos/análise , Resistência Microbiana a Medicamentos/genética , Monitoramento Ambiental , Microbiologia da Água , Poluentes Químicos da Água/análise , Eritromicina , Genes Microbianos , Hibridização in Situ Fluorescente , Lincosamidas/análise , Macrolídeos/análise , Testes de Sensibilidade Microbiana , Estreptogramina B/análise , Estreptogramina Grupo B/análise , Virginiamicina/análise
14.
J Hazard Mater ; 373: 303-312, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-30925390

RESUMO

The degradation of tetracycline by silver vanadate (AgVO3), graphite-like carbon nitride (g-C3N4) and their composites was studied by visible light photocatalysis. Their structures and morphologies were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Their degradation intermediates were analyzed by GC-MS. Nanorod silver vanadate was synthesized by hydrothermal method. The results show that the gap between nanorods is reduced by adding spinning carbon nitride, and the photocatalytic performance of the composite is stronger than that of single material. The reaction rate constants of Ag-AgVO3/g-C3N4 composites were 0.0298 min-1, 2.4 and 2.0 times that of g-C3N4 (K=0.0125 min-1) and AgVO3 (K=0.0152 min-1), respectively. At 120 minutes, the degradation rate of the composites reached 83.6%. The degradation of tetracycline was confirmed by GC-MS, and a possible degradation process was proposed.

15.
J Colloid Interface Sci ; 544: 14-24, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30822602

RESUMO

In this study, we prepared a hydrothermal carbon-based supramolecular organic framework (HTC-MA-TMA) by grafting melamine and trimesic acid on hydrothermal carbon (HTC) for efficient removal of U (VI) from aqueous solutions. The nano-sized supramolecular organic framework (SOF) particles consisted of N-donor-containing melamine and O-donor-containing trimesic acid self-assembled through hydrogen bonds. Their large number of specific active sites acted as the immobilization center for capturing U (VI). Chemical modification facilitated the dispersion of the SOF particles on HTC, which was synthesized using a novel covalent/non-covalent bond strategy. The HTC-MA-TMA adsorbent exhibited exceptional U (VI) adsorption capacity (271.83 mg/g) because of the coordination interaction between UO22+ and its ligands (amino, carboxyl and amide groups). The adsorption equilibrium was achieved within 30 min and followed a pseudo-second-order equation, suggesting the occurrence of a chemical adsorption process. Furthermore, the U (VI) ions adsorbed onto the HTC-MA-TMA adsorbent could be easily desorbed using 0.1 M HNO3 solution. This regeneration caused no significant decrease in the sorption capacity of the adsorbent. These results suggest that advanced HTC-MA-TMA adsorbent can be applied in the nuclear-fuel industry for extracting U (VI) from radioactive wastewater.

16.
Bioresour Technol ; 280: 136-142, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30769324

RESUMO

Recently, a flocculent-granular hybrid reactor was reported as a novel nitrogen removal system; however, the mechanisms of stable operation in the system remain unclear. In this study, the mechanisms of the stable nitrogen removal performance in a flocculent-granular hybrid system were investigated with temperature reduction. The operational period was divided into three phases with different temperatures ranges. In phase I, the nitrogen removal efficiency was stabilized at about 90% with nitrogen removal load maintained at approximately 0.28 kg N/(m3·day). In phase II, while decreasing the temperature to 20 °C, the activities of key enzymes were reduced immediately and were then maintained at a certain level. The relative abundances of aerobic ammonium-oxidizing bacteria and anaerobic ammonium-oxidizing bacteria gradually increased at this phase. In phase III, after the temperature dropped to 15 °C, the activities of key enzymes gradually increased due to adaptation to low temperature, boosting the nitrogen removal efficiency to 83%.


Assuntos
Reatores Biológicos/microbiologia , Microbiota , Nitritos/metabolismo , Nitrogênio/metabolismo , Compostos de Amônio/metabolismo , Processos Autotróficos , Bactérias Anaeróbias , Desnitrificação , Floculação , Oxirredução , Esgotos/microbiologia , Temperatura Ambiente
17.
Braz. j. med. biol. res ; 52(9): e8446, 2019. tab, graf
Artigo em Inglês | LILACS-Express | ID: biblio-1019563

RESUMO

Left atrial diameter (LAD) has been considered an independent risk factor for atrial fibrillation (AF) relapse after pulmonary vein isolation (PVI). However, whether LAD or other factors are more predictive of late recurrence in patients with paroxysmal AF remains unclear. We aimed to evaluate the value of pulmonary vein (PV) parameters for predicting AF relapse 1 year after patients underwent cryoablation for paroxysmal AF. Ninety-seven patients with paroxysmal AF who underwent PVI successfully were included. PV parameters were measured through computed tomography scans prior to PVI. A total of 28 patients had recurrence of AF at one-year follow-up. The impact of several variables on recurrence was evaluated in multivariate analyses. LAD and the time from first diagnosis of AF to ablation maintained its significance in predicting the relapse of AF after relevant adjustments in multivariate analysis. When major diameter of right inferior pulmonary vein (RIPV) (net reclassification improvement (NRI) 0.179, CI=0.031-0.326, P<0.05) and cross-sectional area (CSA) of RIPV (NRI: 0.122, CI=0.004-0.240, P<0.05) entered the AF risk model separately, the added predictive capacity was large. The accuracy of the two parameters in predicting recurrence of AF were not inferior (AUC: 0.665 and 0.659, respectively) to echocardiographic LAD (AUC: 0.663). The inclusion of either RIPV major diameter or CSA of RIPV in the model increased the C-index (0.766 and 0.758, respectively). We concluded that major diameter of RIPV had predictive capacity similar to or even better than that of LAD for predicting AF relapse after cryoablation PVI.

18.
Anal Chem ; 90(24): 14222-14229, 2018 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-30444354

RESUMO

With the rapid development of materials science, on-demand techniques are highly needed with the capability to characterize materials in the micrometer and nanometer scales. In this work, we show that, by employing a prism geometry, total internal reflection sum frequency generation (SFG) vibrational spectroscopy allows for characterizing mesoscopic materials with irregular or complex surfaces. Four representative examples were presented. First, we reveal that mechanical grinding can subtly alter the surface molecular structures of original materials. Second, spin coating can substantially change the surface molecular structures of particle samples. Third, surface restructuring of carboxylated multiwalled carbon nanotubes can happen in response to the surrounding environment. Fourth, surface adsorption and desorption dynamics of toluene on activated charcoal can be traced. Such experiments demonstrate that there are still a broad range of research fields ahead SFG can be directed to, where materials in mesoscopic scales with irregular or complex surfaces can be studied.

19.
Bioresour Technol ; 247: 947-953, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30060434

RESUMO

Realizing the reasonable allocation of resources is possible to solve the dual problems of resources and environment. Therefore, in this study desert cyanobacterium Scytonema javanicum was cultivated in artificial synthetic wastewater to explore the feasibility of nutrient transferring from wastewater to desert. After inoculation, S. javanicum grew well in the wastewater; nitrogen and phosphorus were gradually removed from the wastewater. In general, cyanobacterial biomass, exopolysaccharide content, COD, nitrogen and phosphorus contents were all significantly affected by the cultivation time, wastewater dilution treatment and their interaction (P<0.001). Comprehensively considering the producing period, biomass accumulation and nutrient removal efficiency, cultivation time of cyanobacterium S. javanicum in the synthetic wastewater should be controlled around 20days, with wastewater dilution ratio at 1:1. Conclusively, desert cyanobacterium S. javanicum is a promising species for nutrient transferring from wastewater to desert, and its maximum biomass yield could reach 3.91mgChl-aL-1 in the synthetic wastewater.


Assuntos
Cianobactérias , Clima Desértico , Águas Residuárias , Biomassa , Nitrogênio/metabolismo , Fósforo/metabolismo
20.
J Phys Chem Lett ; 9(17): 5167-5172, 2018 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-30141630

RESUMO

Molecular couplings at interfaces play important roles in determining the performance of nanophotonics and molecular electronics. In this Letter, using femtosecond sum frequency generation to trace free-induction decay of vibrationally excited aromatic thiol molecules immobilized on metal with and without the bridged methylene group(s), metal surface free electron-coupled and uncoupled phenyl C-H stretching vibrational modes were identified, with dephasing times of ∼0.28 and ∼0.60 ps, respectively. For thiols on Au with the bridged methylene group(s) (benzyl mercaptan and phenylethanethiol), both the coupled and uncoupled modes were observed; for thiol on Au without the bridged methylene group (thiophenol), only the coupled mode was observed. This indicates that the bridged methylene group(s) serving as a spacer can be used to adjust the molecular coupling between the phenyl vibration and surface free electrons. The experimental approach can be used to tune molecular couplings in advanced nanophotonics and molecular electronics.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA