Presence Of Hydrogen Source Research Articles

Generalized ratiometric surface-enhanced Raman scattering biosensor for okadaic acid in food based on Au-triggered signal amplification

BackgroundReliability and robustness have been recognized as key challenges for Surface-enhanced Raman scattering (SERS) analytical techniques. Quantifying the concentration of an analyte using a single characteristic peak from SERS has been a controversial topic because the Raman signal is susceptible to highly concentrated electromagnetic hotspots, inhomogeneity of SERS substrate, or non-standardization of measurement conditions. Ratiometric SERS strategies have been demonstrated as a promising solution to effectively balance and compensate for signal fluctuations caused by matrix heterogeneity. However, it is not easy to construct ratiometric SERS sensors with monitoring the ratio of two different signal intensities for target analysis. ResultsAn attempt has been made to develop a novel ratiometric biosensor that can be applied to detect okadaic acid (OA). Aptamer-anchored magnetic particles were first combined with gold-tagged short complementary DNA (Au-cDNA) to create heterogeneous nanostructures. When the target was present, the Au-cDNA was dissociated from nanostructures, and 4-nitrothiophenol (4-NTP) was initiated to reduce to 4-aminothiophenol (4-ATP) in the presence of hydrogen sources. The SERS ratio change of 4-NTP and 4-ATP was finally detected by AuNPs-coated film. OA was successfully quantified, and the detection limit was as low as 2.4524 ng/mL. The constructed biosensor had good stability and reproducibility with a relative standard deviation of less than 4.47%. The proposed method used gold nanoparticles as an intermediate to achieve catalytic signal amplification and subsequently increased the sensitivity of the biosensor. Significance and noveltyCatalytic reaction-based ratiometric SERS biosensors combine the multiple advantages of catalytic signal amplification and signal self-calibration and provide new insights into the development of stable, reproducible, and reliable SERS detection techniques. This ratiometric SERS technique offered a universal method that is anticipated to be applicable for the detection of other targets by substituting the aptamer.

Catalytic conversion mechanism of guaiacol as the intermediate of lignin catalytic pyrolysis on MgO surface: Density functional theory calculation

MgO has better catalytic effect on the alkylation reactions of methoxy phenols in the pyrolysis of lignin to form alkylated phenols, thus, the research on the conversion mechanism of methoxy phenols into alkylated phenols on the MgO surface is necessary. In this study, the catalytic conversion mechanism of guaiacol as a model compound of methoxy phenols on the MgO surface is investigated by density functional theory calculations. The possible reactions for the conversion of guaiacol on the clean MgO(100) and the H atom pre-adsorbed MgO(100) surfaces are discussed. The adsorption energies, adsorption structures, electronic structures, and energy barriers of guaiacol on the MgO(100) surfaces are obtained to illustrate the impact of pre-adsorbed H atom on the adsorption of guaiacol and the conversion mechanism of guaiacol. The results indicated that a hydrogen bond is generated between the O1 atom of guaiacol molecule and the pre-adsorbed H atom, resulting in the adsorption energy of guaiacol molecule on the MgO(100) surface is lower than that on the H atom pre-adsorbed MgO(100) surface. The energy barriers for the conversion of guaiacol molecule to form o-cresol molecule on the clean MgO(100) surface is higher than generate catechol molecule on the H atom pre-adsorbed MgO(100) surface. Thus, the results indicate that the presence of hydrogen source has a promotion effect on the conversion of methoxy phenols over MgO catalyst into alkylated phenols.

Sustainable Carbons and Fuels: Recent Advances of CO2 Conversion in Molten Salts

The massive release of the greenhouse gas CO2 has resulted in numerous environmental issues. In searching for advanced technologies for CO2 capture/conversions, recent advances in electrochemical reduction of CO2 in molten salts shed a light on potential solutions to CO2 mitigation. Electro-reduction of CO2 in molten salts exhibits features like high selectivity and efficiency towards sustainable carbons and fuels, low toxicity, and possibility to combine with in situ CO2 capture. In this Minireview, we highlight the tuning of the products in this process and mainly discuss two categories of electrolyte, carbonate-based molten salts (CMS) and those based on halides (HMS). Depending on the synthetic conditions, fuels such as CO or hydrocarbons (in the presence of hydrogen source, i. e., LiOH, NaOH, or KOH in the electrolyte) as well as high-value nanostructured carbons including carbon nanotubes, carbon nanofibers, carbon nano-onions, and graphene can be obtained with high efficiency. The synthesis parameters are compared, and the applications of as-obtained carbons are briefly summarized. Additionally, some perspectives on this technology are also discussed.

Electrocatalytic Hydrogen Evolution Reaction of Metal Organic Frameworks decorated with poly (3-aminobenzoic acid)

Advanced materials for hydrogen evolution reaction are central to the area of renewable energy. Here, we developed a solvothermal synthesis of metal organic framework (MOF) nanoparticles decorated with poly (3-aminobenzoic acid) (PABA) referred as MOF-3.6wt.%-PABA and MOF–5wt.%-PABA composites. The parent material (MOF) and composites were characterized by ultraviolet visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDS, EDX), selected area electron diffraction (SAED) and cyclic voltammetry (CV). Detailed structural and morphological characterizations established that PABA interacts with MOF on the external surface as observed by appearance of rough surface of the composites. The XRD and SAED showed that MOF and composites are crystalline and the presence of PABA did not alter the crystallinity of the material. Experiments probing the thermal, electrochemical and photophysical properties revealed that the composites were very stable and robust and had exceptionally properties. Significant hydrogen evolution reaction (HER) using CV and Tafel plots, was generated by MOF and composites in dimethyl sulfoxide/tetrabutylammonium perchlorate (DMSO/TBAP) supporting electrolyte in the presence of hydrogen source by applying a negative potential to the electrode.

Hydrogen migration on the C60 fullerene

We investigate the migration barriers, transition states, and optimum migration paths of hydrogen on the C60 fullerene using the ab initio density functional theory. Calculated energy barriers tend to be higher for non-local exchange-correlation functionals. We find that the migration between adsorption sites with the same energy has high migration barriers, and thus the initial stages of the H nucleation requires desorption–adsorption cycles. The migration barrier is reduced near another H adsorbate. The migration may be involved more in the later stages of the regio-selective hydrogenation of C60. We find that the migration barriers are reduced by the presence of hydrogen sources, and the hydrogenating agents in the environment are required in order to reach the regio-selective hydrogenation of the C60 fullerene.

Phase transformations of Mg2NiH4 at high-pressure thermal treatment

In situ synchrotron X-ray experiments were performed on Mg2NiH4 under high pressures (<6GPa) and temperatures (<600°C) with an internal hydrogen source, i.e. LiAlH4. The transformation from the monoclinic low temperature form to a structure similar to the cubic high-temperature form was induced by application of gigapascal pressures. Upon heating above 200°C at 5GPa, a transformation to the cubic HT form took place as expected, followed by the appearance above 300°C of a new high-pressure phase and in the presence of hydrogen source also the decomposition product NiH. The unit cell parameter was calculated at different pressures and temperatures for the cubic form as well as the compressibility revealing sensibility to both compression and thermal expansion.

The study of rate improvement of trichloroethene (TCE) decay in UV system with hydrogen source

The photosensitization of trichloroethene (TCE) in the presence of hydrogen source of surfactant and photosensitizer was investigated. Photolysis experiments were conducted with a Rayonet RPR-200 merry-go-round photoreactor at 253.7 nm. Solutions containing fixed amount of TCE and surfactant Brij 35 were exposed to UV illumination with different concentrations of acetone (ACE). Quantum yield in solution with surfactant Brij 35 and optimum ACE dosage is about 25 times higher than that in Brij 35 alone. However, with an excess ACE dosage, it would act as a light barrier which attenuates the light intensity for TCE photodegradation. A mathematical model is therefore developed for the prediction of TCE photodegradation in Brij 35 solution containing various ACE concentrations, in which the remaining fraction of TCE (C/C0) in the system can be determined. Apart from the direct photodegradation, photosensitization is postulated to be another major pathway contributing to the overall decay.

A plausible reaction pathway of asphaltene under ultrasound

In an earlier report [Energy Fuels, 7 (1993) 111], the potential benefits of a refining process for heavy oil through the chemical assisted ultrasound method at room temperature and ambient pressure were presented. Specifically, with the effects of cavitation and added surfactant, within 15 min from the original bitumen, 35% of asphaltene was converted into gas oil and resin fractions. The present investigation is a continuous effort to provide more information about this conversion process, particularly studying the role of water during the ultrasound conversion process. The question to be answered is: “To what degree is the participation of hydrogen, which was used for the conversion process, a result from the water medium?” In order to trace the fate of hydrogen in a water medium, deuterium oxide was chosen to compare with the water medium, and sodium borodeuteride was chosen to compare with sodium borohydride as a source of the reducing agent. Adopting nuclear magnetic resonance (NMR) as a tool, the results were tentatively concluded that both dehydrogenation and cracking reactions occurred under ultrasound. It was also observed, in the case of the water medium without the presence of hydrogen sources, that the principle reaction is dehydrogenation accompanied with minor cracking. The cracking increases considerably only after a hydrogen source is introduced. Simultaneous cracking and dehydrogenation are involved at the expanses of the naphthenic hydrogen type in asphaltene of the reaction pathway scheme.

F119. Alterations in microvascular flow resistance due to capillary plugging by leukocytes in cremaster muscle

Advanced materials for hydrogen evolution reaction are central to the area of renewable energy. Here, we developed a solvothermal synthesis of metal organic framework (MOF) nanoparticles decorated with poly (3-aminobenzoic acid) (PABA) referred as MOF-3.6 wt.%-PABA and MOF–5 wt.%-PABA composites. The parent material (MOF) and composites were characterized by ultraviolet visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDS, EDX), selected area electron diffraction (SAED) and cyclic voltammetry (CV). Detailed structural and morphological characterizations established that PABA interacts with MOF on the external surface as observed by appearance of rough surface of the composites. The XRD and SAED showed that MOF and composites are crystalline and the presence of PABA did not alter the crystallinity of the material. Experiments probing the thermal, electrochemical and photophysical properties revealed that the composites were very stable and robust and had exceptionally properties. Significant hydrogen evolution reaction (HER) using CV and Tafel plots, was generated by MOF and composites in dimethyl sulfoxide/tetrabutylammonium perchlorate (DMSO/TBAP) supporting electrolyte in the presence of hydrogen source by applying a negative potential to the electrode.