教学课程资源库 更多>>

关键词： charge transfer   donor-acceptor   fluorescence   organic light-emitting diodes   triplet-triplet annihilation  

摘要： Novel electron donor-acceptor-donor (D-A-D) compounds comprising dibenzo[a,j]phenazine as the central acceptor core and two 7-membered diarylamines (iminodibenzyl and iminostilbene) as the donors have been designed and synthesized. Investigation of their physicochemical properties revealed the impact of C-2 insertion into well-known carbazole electron donors on the properties of previously reported twisted dibenzo[a,j]phenazine-core D-A-D triads. Slight structural modification caused a drastic change in conformational preference, allowing unique photophysical behavior of dual emission derived from room-temperature phosphorescence and triplet-triplet annihilation. Furthermore, electrochemical analysis suggested sigma-dimer formation and electrochemical polymerization on the electrode. Quantum chemical calculations also rationalized the experimental results.

关键词： Renewable diesel   hydroprocessing   decarboxylation   decarbonylation   hydrodeoxygenation  

摘要： Petroleum-derived fuels are traditionally used in transport, power generation, and various other applications, but they are limited and cause environmental degradation. Renewable diesel (RD) is a promising substitute for diesel. Hydroprocessing is a technique used in producing RD. The triglycerides in vegetable oil are transformed into a fuel having a molecular structure similar to that of petro-diesel. RD is used as a "drop-in" fuel, with high cetane index and good cold flow properties. The present study reviews the production mechanism of RD, its physiochemical properties, and its use as a CI engine fuel.

关键词： Reaction products   Reaction mechanisms   Carbon   Surface reactions   Oxidation  

摘要： Pyrolysis of solid fuels forms a solid carbon-rich fuel, also called char, whose physico-chemical description is rather complex. Heterogeneous oxidation reactions take place during thermochemical conversion of char. The present work proposes a predictive detailed kinetic model, opening a new path for a deeper understanding of the char conversion process. This model considers porosity, surface area, density of surface sites, and their evolution along the conversion process. The chemical aspects of char oxidation are modeled assuming a carbonaceous bulk structure, surrounded by a variety of surface sites which represent the chemical functionalities typically present in such materials. The heterogeneous chemical reactions and their kinetic parameters are defined based on previous studies in the literature and by analogy to homogeneous gas-phase reactions of aromatic species. A mathematical framework is proposed to couple physical and chemical descriptions of the oxidation process. Although the proposed model benefits from experimental information, it is able to comprehensively describe the conversion rate of a broad range of carbonaceous materials such as carbon nanotubes, graphite, and chars only on the basis of their elemental composition. The proposed model represents a first step in exploring the explicit and coupled treatment given to the physical and chemical evolution of the fuel throughout its conversion, allowing us to consistently describe the particle evolution, opening a path for reliable models to manage the chemistry of char conversion.

关键词： Curcumin complex   Gallium   Photodynamic therapy   Breast cancer  

摘要： The synthesis, detailed structural and physicochemical characterization of a novel Ga(III)-curcumin complex with the ancillary aromatic chelator 1,10-phenanthroline is presented herein. The complex constitutes the only crystallographically characterized structure with Ga(III) as the metal core and a curcuminoid as the ligand. The photophysical properties of the complex revealed a significant red-shift in absorption, increased photostability and comparable free radical generation compared to plain curcumin. They all are highly desirable properties for a photosensitizer. Photodynamic therapy is a non-invasive method for the treatment of various cancers which requires a photosensitizing molecule able to generate reactive oxygen species upon light irradiation. Curcumin has been studied as a promising photosensitizer against cancer cells and metal complexation has been shown to increase its photodynamic effect. The novel curcumin-Ga complex exhibited no dark toxicity at low concentrations against MCF-7 breast cancer cells and upon irradiation a light-dose dependent decrease in cell survival was observed. This photodynamic effect was superior to the one caused by curcumin alone making the Ga(III)-curcumin complex a more promising photosensitizer than the parent ligand. (c) 2021 Elsevier B.V. All rights reserved.

关键词： Landfill leachate   Physicochemical composition   Toxicity  

摘要： The inevitable consequence of the operation of landfills is the emission of leachate, which is considered to be one of the main polluters of the ground and water environment. The leachate contains soluble organic compounds, inorganic contaminants, suspended solids, heavy metals and dangerous substances. The selection of the leachate disposal method requires a comprehensive assessment of its properties. Therefore, the physicochemical parameters and toxicity tests were chosen for a comprehensive assessment of the properties of leachate. Four municipal waste landfills (operational and non-operational) were selected for the study, for which multidimensional statistical analyses were carried out. The study was conducted between the period of April 2018 and December 2019. The comprehensive assessment showed that pollutants in leachate from the analyzed landfills remained at a level which did not allow them to be discharged to water or soil. The presence of substances particularly harmful to the aquatic environment (e.g AN, chromium, copper) may hinder their treatment together with household sewage, as it involves obtaining a permit required under laws. Toxicity of leachate may also be a problem, as it may persist after the treatment process is completed. The values of pH, EC and the concentrations of ON, TDS, TSS, chloride, iron and manganese had the strongest influence on the properties of leachate from all landfills. For operational landfills, these were also calcium concentrations, for non-operational ones COD, TU and the concentrations of TKN, AN, TS, sodium, potassium and magnesium. The mentioned parameters also showed strong correlation with other physicochemical properties of the leachate, which indicate their suitability for the monitoring of leachate and the aquatic environment in the vicinity of municipal waste landfills.

关键词： Extensive green roofs   Growing media   Agricultural wastes   Low impact urban design and development  

摘要： Green roof substrates provide water, nutrients, and physical support to vegetation development, as well as being a key element in the hydrological performance of the system. In this regard, the use of aggregate components that improve physicochemical properties of the substrates optimises the ecosystem services provided by green roofs. This study demonstrates the effects of using rice husk as an aggregate material in engineered substrates for extensive green roofs. Sixteen different substrates compositions were tested with different proportions of natural (NRH) and carbonized (CRH) rice husk incorporated into a base mixture with fixed proportions of vermicompost, vermiculite, and construction waste. The study consists of two phases: i) laboratory analyses to assess the sub-strates' physicochemical properties, and ii) a pilot-scale field experiment to evaluate hydrological performance under real subtropical climate conditions and vegetation development using a monoculture planting of Sedum rupestre. The findings showed that CRH has the potential to improve some physicochemical properties, such as water holding capacity, bulk density, and porosity. Additionally, CRH substrates presented a slightly increased average retention rate (up to 7%) comparing to local topsoil. The average stormwater retention rate for all engineered substrates was 77.73%. Multiple linear regression models were satisfactorily fitted to observed data from the open field experiment allowing an estimation of potential substrates' retention rates. Moreover, vegetation development was positively affected by adding CRH comparing to the NRH. Carbonized rice husk presents as a useful material for improving green roof substrates properties and could be a sustainable alternative for local agriculture waste management.

关键词： Kynurenic acid   Cyclodextrin   Inclusion complex   Physicochemical   Stability  

摘要： In this work, the interaction between Kynurenic acid (KYNA) and several natural and modified cyclodextrins (CDs) is carried out. Among all the CD tested, HP beta-CD showed the strongest complexation constant (K-F), with a value of 270.94 +/- 29.80 M-1. Between natural (alpha- and beta-) CDs, the complex of KYNA with beta-CD was the most efficient. The inclusion complex of KYNA with CDs showed a strong influence of pH and temperature. The K-F value decreased at high pH values, when the pK(a) was passed. Moreover, an increase of the temperature caused a decrease in the K-F values. The thermodynamic parameters of the complexation (Delta H degrees, Delta S degrees and Delta G degrees) were studied with negative entropy, enthalpy and spontaneity of the process at 25 degrees C. Moreover, the inclusion complex was also characterized using FTIR and TGA. Finally, molecular docking calculations provided different interactions and their influence in the complexation constant.

关键词： Biofiltration   Butyric acid   Microbial taxonomy   Multidisciplinary analysis   Odor removal   Packing material  

摘要： The influence of bed material on the odor removal performance of a biofilter was studied. A compost-wood biofilter and a wood biofilter were treated with a gaseous stream contaminated with butyric acid and comparatively evaluated at pilot scale using olfactometric, physico-chemical and microbiological approaches. The variables analyzed in both biofilters were correlated with specific families of their microbiota composition. In addition to a higher nutrients content (nitrogen and phosphorus), the compost-wood biofilter registered maximum values in number of aerobic microorganisms (3.6.108 CFU/g) and in aerobic microbiological activity (approximate to 40 mg O2/g VS of cumulative oxygen demand at 20 h). This may explain the higher performance of this biofilter compared to the wood biofilter, withstanding odor loads of up to 1450 ouE/m2.s with odor removal efficiencies close to 100%. The analysis of the microbial community showed that Actinobacteria, particularly the mostly aerobic Microbacteriaceae family, might play an important role in butyric acid degradation and hence reduce odor impact. The multidisciplinary analysis carried out in this work could be a very useful strategy for the optimal design of biofiltration operations.

关键词： Natural fermentation   Morphological properties   Highlands barley   Molecular-weight  

摘要： The influence of natural fermentation on the highlands barley starch chemical structure, morphological, physicochemical, and thermal properties was studied. The findings showed that fermentation had no impact on starch fine structure but it decreased the molecular-weight from 2.26 to 1.04 x 108 g/mol in native highlands barley and after 72 h fermentation (FHB72) respectively. Also, it decreased amylopectin long-chains (B1 and B2) while increased short-chains. The intensity ratio of FT-IR at 995/1022 and 1047/1022 bands were found to be higher as the time of fermentation progressed, and the highest absorption-intensity at 3000-3600 cm-1 and higher swelling capacity were noticed in the starch of FHB72. During fermentation, pasting peak, final and setback viscosities were decreased. Microscopically, granules with more pores, damaged, cracked, and no growth rings were found in starches isolated after 48 h and 72 h of fermentation. This study indicated that fermentation up to 72 h is an effective method to modify highlands barley starch.