改进的石墨烯基材料用作菜籽油转酯化反应制生物柴油的有效催化剂（英文）

本文研究了不同石墨烯基材料用作转酯化反应制备生物柴油催化剂的性能.将磺酸基或磷酸盐基嫁接到热还原的氧化石墨烯表面,制备了固体酸石墨烯基样品.并采用扫描电镜、X射线衍射、热重分析、X射线光电子能谱、N_2吸附-脱附法、电位滴定法、元素分析以及红外光谱法对所制样品进行了全面表征.将所制样品用于130℃带压力的条件下菜籽油与甲醇转酯化反应中,并将其催化活性与商用的多相酸催化剂Amberlyst-15的进行了比较.结果表明,所有改进的样品在转酯化反应中均表现出催化活性,但各样品上生物柴油产率差别较大.其中以苯二氮磺酸基功能化的热还原氧化石墨烯样品上脂肪酸甲酯产率最高,反应6 h后达70%,也明显高于商用催化剂Amberlyst-15.该样品也表现出良好的重复使用性能.     

Catalytic Performance of Spherical MCM-41 Modified with Copper and Iron as Catalysts of NH3-SCR Process

Spherical MCM-41 with various copper and iron loadings was prepared by surfactant directed co-condensation method. The obtained samples were characterized with respect to their structure (X-ray diffraction, XRD), texture (N₂ sorption), morphology (scanning electron microscopy, SEM), chemical composition (inductively coupled plasma optical emission spectrometry, ICP-OES), surface acidity (temperature programmed desorption of ammonia, NH₃-TPD), form, and aggregation of iron and copper species (diffuse reflectance UV-Vis spectroscopy, UV-Vis DRS) as well as their reducibility (temperature programmed reduction with hydrogen, H₂-TPR). The spherical MCM-41 samples modified with transition metals were tested as catalysts of selective catalytic reduction of NO with ammonia (NH₃-SCR). Copper containing catalysts presented high catalytic activity at low-temperature NH₃-SCR with a very high selectivity to nitrogen, which is desired reaction products. Similar results were obtained for iron containing catalysts, however in this case the loadings and forms of iron incorporated into silica samples very strongly influenced catalytic performance of the studied samples. The efficiency of the NH₃-SCR process at higher temperatures was significantly limited by the side reaction of direct ammonia oxidation. The reactivity of ammonia molecules chemisorbed on the catalysts surface in NO reduction (NH₃-SCR) and their selective oxidation (NH₃-SCO) was verified by temperature-programmed surface reactions.     

Activation of the Normal Human Skin Cells by a Portable Dielectric Barrier Discharge-Based Reaction-Discharge System of a Defined Gas Temperature

Skin injury leading to chronic wounds is of high interest due to the increasing number of patients suffering from this symptom. Proliferation, migration, and angiogenesis are key factors in the wound healing processes. For that reason, controlled promotion of these processes is required. In this work, we present the portable helium-dielectric barrier discharge (He-DBD)-based reaction-discharge system of controlled gas temperature for biological activities. To make this He-DBD-based reaction-discharge system safe for biological purposes, a multivariate optimization of the operating parameters was performed. To evaluate the effect of the He-DBD operating parameters on the rotational gas temperature T_rot(OH), a design of experiment followed by a Response Surface Methodology was applied. Based on the suggested statistical model, the optimal operating conditions under which the T_rot(OH) is less than 37 °C (310 K) were estimated. Then, the resulted model was validated in order to confirm its accuracy. After estimation the optical operating conditions of He-DBD operation, the spectroscopic characteristic of the He-DBD-based reaction-discharge system in relevance to the several optical temperatures in addition to electron number density has been carried out. Additionally, the qualitative and quantitative analyses of the reactive oxygen species and reactive nitrogen species were performed in order to investigate of reactions and processes running in the He-DBD-gaseous phase and in the He-DBD-treated liquid. Next, the developed portable He-DBD-based reaction-discharge system, working under the optimal operating conditions, was used to stimulate the wound healing process. It was found that a 30 s He-DBD treatment significantly increased the proliferation, migration, and angiogenesis of keratinocytes (HaCaT) and fibroblasts (MSU-1.1) cell lines, as well as human skin microvascular endothelial cells (HSkMEC.2). Hence, the application of the cold atmospheric pressure plasma generated in this He-DBD-based reaction-discharge system might be an alternative therapy for patient suffering from chronic wounds.

     

Novel tris(5-aryl-1H-tetrazol-1-yl)methanes and 2-dichloromethyl-5-aryl-2H-tetrazoles and noncovalent interactions in their crystal structure

A series of tris(5-aryl-1H-tetrazol-1-yl)methanes ( 3a-3g ) and 2-dichloromethyl-5-aryl-2H-tetrazoles ( 4a-4d ) were synthesized by reaction of 5-aryl-NH-tetrazoles with trichloromethane in strong aqueous basic condition. The compounds obtained were fully characterized by means of HRESI-MS, ¹H and ¹³C{¹H} NMR spectroscopies, as well as by single-crystal X-ray diffraction (for 3a , 3b , 4d ). Inspection of the X-ray diffraction data and Hirshfeld surface analysis for tris(5-aryl-1H-tetrazol-1-yl)methanes 3a , b and 2-dichloromethyl-5-aryl-2H-tetrazole 4d showed the presence of noncovalent π-hole•••lone pair and π-hole•••π interactions involving electrophilic tetrazole carbon atom.     

A Simple Approach to Vicinal Pyrrolylphosphane Aldehydes

A simple approach to vicinal pyrrolylphosphane aldehydes was developed. The reaction of Alder's dimer 1 with a set of pyrrolylphosphane derivatives—its oxides, sulfides, and selenides—was studied in detail. While Alder's dimer reacted with phosphane oxides and sulfides at the O and S atoms, phosphane selenides 4a–c were found to be suitable for the introduction of the formyl group into the pyrrole ring. The reaction of highly electrophilic Alder's dimer with pyrrolylphosphane selenides proceeded predominantly at the pyrrolyl nuclei, affording the corresponding aldehydes. The phosphoroselenoyl groups of aldehydes 11 were reduced either with Raney Ni or hexamethylphosphorustriamide under mild conditions, affording pyrrolylphosphane aldehydes 12 .     

Lateral resolution in focused electron beam-induced deposition: scaling laws for pulsed and static exposure

In this work, we review the single-adsorbate time-dependent continuum model for focused electron beam-induced deposition (FEBID). The differential equation for the adsorption rate will be expressed by dimensionless parameters describing the contributions of adsorption, desorption, dissociation, and the surface diffusion of the precursor adsorbates. The contributions are individually presented in order to elucidate their influence during variations in the electron beam exposure time. The findings are condensed into three new scaling laws for pulsed exposure FEBID (or FEB-induced etching) relating the lateral resolution of deposits or etch pits to surface diffusion and electron beam exposure dwell time for a given adsorbate depletion state.     

Characterization of partially inverse spinel ZnFe2O4 with high saturation magnetization synthesized via soft mechanochemically assisted route

ZnFe₂O₄ was prepared by a soft mechanochemical route from two starting combinations of powders: (1) Zn(OH)₂/α-Fe₂O₃ and (2) Zn(OH)₂/Fe(OH)₃ mixed in a planetary ball mill. The mechanochemical treatment provoked reaction leading to the formation of the ZnFe₂O₄ spinel phase that was monitored by XRD, TEM, IR and Raman spectroscopy. The spinel phase was first observed after 4 h of milling and its formation was completed after 18 h in both the cases of starting precursors. The synthesized ZnFe₂O₄ has a nanocrystalline structure with a crystallite size of about 20.3 and 17.6 nm, for the cases (1) and (2), respectively. In the far-infrared reflectivity spectra are seen four active modes. Raman spectra suggest an existence of mixed spinel structure in the obtained nanosamples. In order to confirm phase formation and cation arrangement, Mössbauer measurements were done. Estimated degree of inversion is about 0.58 for both starting mixtures. The magnetic properties of the prepared ZnFe₂O₄ powders were also studied. The results show that the samples have a typical superparamagnetic-like behavior at room temperature. Higher values of magnetization in the case of samples obtained with starting mixture (2) suggest somewhat higher degree of cation inversion.     

Development of a rapid resolution HPLC method for the separation and determination of 17 phenolic compounds in crude plant extracts

Rapid Resolution HPLC/DAD method, on a 1.8 μm, 4.6×50 mm column, was developed to enable a rapid separation of a mixture of 17 compounds, which consisted of hydroxybenzoic acids, hydroxycinnamic acids, flavones, flavonols, flavanone, flavonol-glycoside and antraquinone, in a single run, within 22 minutes. The developed method is precise, accurate and sensitive enough for simultaneous quantitative evaluation of major compounds in crude and hydrolyzed extracts of parsley, buckthorn, mint, caraway and birch. In order to overcome the inability to quantify all the phenolic compounds present in the samples caused by lack of external standards, HPLC approaches for the total phenolic content estimation based on sum of all integrated peak areas were made. These results were compared with the total phenolic content determined by Folin-Cioacalteu method. Although the correlation between the series of data was not significant (p<0.05), the difference between the results of total phenolic content obtained spectrophotometrically and by HPLC was not high in the case of parsley, buckthorn and mint extract. Regarding the obtained results, the HPLC approach could serve as an excellent tool for total phenolic content estimation, without the need for complete identification of the individual compounds.      

Syntheses and structures of the first terminal phosphanylphosphido complex of hafnium [Cp2Hf(Cl){η(1)-(Me3Si)P-P(NEt2)2}] and the first zirconocene-phosphanylphosphinidene dimer [Cp2Zr{μ(2)-P-P(NEt2)2}2ZrCp2

Reactions of (Et(2)N)(2)P-P(SiMe(3))Li with [Cp(2)MCl(2)] (M = Zr, Hf) in toluene or pentane yield the related terminal phosphanylphosphido complexes [Cp(2)M(Cl){η(1)-(Me(3)Si)P-P(NEt(2))(2)}]. The solid state structure of [Cp(2)Hf(Cl){η(1)-(Me(3)Si)P-P(NEt(2))(2)}] was established by single crystal X-ray diffraction. The reaction of (Et(2)N)(2)P-P(SiMe(3))Li with [Cp(2)ZrCl(2)] in THF or DME solutions leads to the formation of deep red crystals of the first neutral diamagnetic zirconocene-phosphanylphosphinidene dimer [Cp(2)Zr{μ(2)-P-P(NEt(2))(2)}(2)ZrCp(2)]. The molecular structure of this compound was confirmed by X-ray diffraction. The reactions of (R(2)N)(2)P-P(SiMe(3))Li with [CpZrCl(3)] yield the related tetraphosphetanes R(2)NP(μ(2)-PSiMe(3))(2)PNR(2), which apparently are formed as a result of a transfer of NR(2) groups from a P atom to the Zr atom.     

Chemiluminescent reductive acridinium triggering (CRAT)--mechanism and applications

Acridinium esters traditionally are triggered using basic hydrogen peroxide. By serendipity, we have found that acridinium esters can also be triggered with emission of chemiluminescence by reductive triggering, e.g., by zinc metal or reduced forms of ferric and cupric salts. Furthermore, organic reducing compounds like dithiothreitol, tricarboxyethylphosphine or glutathione could be used in combination with organic oxidants like quinones or inorganic ferric or cupric salts. Mechanisms are proposed which involve the intermediacy of superoxide. Two forms of reactive oxygen species (i.e., hydrogen peroxide and superoxide) could be discriminated based on differences in kinetics. Some applications (improved detection of acridinium ester, use of acridinium ester as redox probes) are discussed.