Characterization and identification of chemical compositions in the extract of Artemisia rupestris L. by liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry

Liquid chromatography coupled to negative electrospray ionization (ESI) tandem mass spectrometry (MS/MS) employing a time-of-flight tandem mass spectrometer was used in the structural determination of phenolic compounds and sesquiterpenoids occurring in the extract from Artemisia rupestris L. A total of 91 compounds including chlorogenic acid derivatives, flavonoids (aglycone, O-glycosyl, C-glycosyl and C,O-glycosyl), 2-phenoxychromones and guaiane sesquiterpenoids were identified by comparing the retention time and fragmentation behavior with reference standards or according to accurate mass measurement and the characteristic fragmentation at low and high collision energy. Most of these compounds were reported in Artemisia rupestris L. for the first time. Meanwhile, the proposed pathway and the major diagnostic fragmentation of 2-phenoxychromone and rupestonic acid were investigated to trace 2-phenoxychromone and rupestonic acid derivatives in crude plant extracts. According to these rules, we have successfully characterized five potential novel compounds including three 2-phenoxychromones (6-demethoxy-4'-O-methylcapillarisin-O-hexosylglucuronide, 6-demethoxy-4'-O-methylcapillarisin-O-pentosylhexoside and 6-demethoxy-4'-O-methylcapillarisin-O-deoxyhexosylhexoside) and two sesquiterpenoids (hexosyl-glycurinide-rupestonic acid and hexoside-rupestonic acid).     

Role of Vitamins B-3 and C in the Fashioning of Granules in UASB Reactor Sludge

Whereas a myriad of possible factors have been reported which effect the formation of granules in a upflow anaerobic sludge blanket (UASB) reactor and influence their properties, there is no study on the effect of vitamins on the granulation of UASB reactor sludge. The present study was undertaken to bridge this gap. It was seen that vitamins helped in better granule formation??as reflected by favorable size distribution, sludge volume index, and settling velocity??compared to controls. The vitamin-spiked reactors also achieved >85?% COD removal efficiency in half the number of days the unspiked reactors took. The vitamin supplements were effective at concentrations????1?mg/l. Hence, their use in expediting granule formation as also in developing better-quality granules appears economically viable.     

Evaluation of rheological properties and swelling behaviour of sonicated scleroglucan samples

Scleroglucan is a natural polysaccharide that has been proposed for various applications. However there is no investigation on its property variations when the molecular weight of this polymer is reduced. Scleroglucan was sonicated at two different polymer concentrations for different periods of time and the effect of sonication was investigated with respect to molecular weight variations and rheological properties. Molar mass, estimated by viscometric measurements, was drastically reduced already after a sonication for a few min. Sonicated samples were used for the preparation of gels in the presence of borate ions. The effect of borax on the new samples was investigated by recording the mechanical spectra and the flow curves. A comparison with the system prepared with the dialysed polymer was also carried out. The anisotropic elongation, observed with tablets of scleroglucan and borax, was remarkably reduced when the sonicated samples were used for the preparation of the gels.     

A new chromone from seeds of <Emphasis Type="Italic">Cydonia oblonga</Emphasis>

The new chromone 5,7-dihydroxy-2-n-pentacosanylchromen-4-one (1) in addition to the three known compounds ursolic acid (2), tormentic acid (3), and β-daucosterol (4) were isolated from seeds of Cydonia oblonga. Their structures were determined based on their 1D and 2D NMR and HR-ESI-MS spectral data.     

Dynamic pressure based prediction of spray cooling heat transfer coefficients

An important goal of spray cooling research is the ability to predict local heat transfer from the spray hydrodynamics. It is postulated that the local normal pressure exerted by the spray onto the heated surface can be used to obtain the local heat transfer coefficient. This hypothesis was tested using data obtained from hollow cone, full cone, and linear sprays at four nozzle pressures and three stand-off distances. A correlation between the pressure and heat transfer coefficient was determined from the data, then used to “predict” the heat transfer coefficient to verify the accuracy of the correlation. The area averaged heat transfer coefficient could be predicted within 25%, indicating that pressure can be used to predict the local heat transfer coefficient in the single-phase regime.     

2-[(4-Aminobutyl)ferrocenylmethylidene]-5,6-dimethoxy-1-indanone derivatives: Synthesis,characterization, and investigation of electro-optical properties

A ferrocenyl-based, chromophore-containing 1-indanone derivative was synthesized through crotonic condensation between 4-chlorobutylferrocenecarboxaldehyde and 5,6-dimethoxy-1-indanone followed by the nucleophilic substitution of chlorine atom of the obtained dyad with different aromatic and aliphatic amines. The electrochemical and optical properties of the synthesized compounds were investigated to explore the relationship between their structures and optical and electrochemical properties. The bandgaps determined from optical absorption spectra ranged from 2.05 to 2.15 eV. The important electrochemical parameters, including the peak potential separation, peak current ratios, and the dependence of peak currents on the scan rate, were studied. Results showed an electrochemically reversible redox system with diffusion-controlled redox process for the synthesized compounds. The study of quantum chemistry was performed on the synthesized compounds using the density functional theory approach. The B3LYP method and 6-311 G(d) basis set were used for optimizing the structures in the gas phase. The theoretical and experimental results show that these compounds can be considered as candidates to be used in optical applications.     

A new supramolecular zinc(II) complex containing 4‐biphenylcarbaldehyde isonicotinoylhydrazone ligand: Nanostructure synthesis,catalytic activities and Hirshfeld surface analysis

A new potentially tridentate hydrazone ligand, 4‐biphenylcarbaldehyde isonicotinoylhydrazone (4‐bpinh), was prepared by the condensation of biphenyl‐4‐carboxaldehyde with isonicotinic acid hydrazide. Then, its nano‐sized and single crystal of zinc complex were synthesized using sonochemical and heat gradient methods, respectively. The structure of complex, [Zn(4‐bpinh)₂ Br₂] (1), was determined by single‐crystal X‐ray diffraction, FT‐IR, and elemental analysis, and the nano‐structure of complex was characterized by FT‐IR, XRD, and SEM. The single crystal X‐ray structure of complex showed that the metal center has a distorted tetrahedral geometry and the hydrazone ligand acts as monodentate trough the pyridyl N atom. Moreover, the analysis of crystal structures indicates the existence of intermolecular interactions such as N/C–H?Br/O, N/C–H?π, and π?π stacking in the stabilization of complex structure which finally led to the formation of the three‐dimensional supramolecular structure. Also, the impact of this interactions was more studied using Hirshfeld surface analysis and corresponding 2D fingerprint plots. Furthermore, the catalytic activity of 1 was studied in the selective oxidation of various sulfides to corresponding sulfoxides using hydrogen peroxide as the oxidative agent.     

Cobalt-promoted MoS2 nanosheets: A promising novel diesel hydrodesulfurization catalyst

MoS₂ has been commonly used as a catalyst in hydrodesulfurization (HDS) of petroleum cuts in crude oil refineries. In this study, the synthesis of unsupported MoS₂ and Co-promoted MoS₂ nanosheets produced from molybdenum oxide and thiourea is reported. The synthesized samples were characterized by using x-ray fluorescence, x-ray diffraction, Brunauer–Emmett–Teller (BET), temperature-programmed reduction, thermal gravimetric analysis, and transmission electron microscopy methods, and then they were utilized for HDS of diesel through a fixed-bed catalytic reactor. Results indicated that a cobalt promoter affected both the number and the performance of active sites of the molybdenum sulfides, and the activity of the promoted MoS₂ catalyst was consistently higher than that of the MoS₂ catalyst. More significantly, the activity of the promoted catalyst was slightly declined during 48 h continuous HDS reaction, which indicated the stability of this catalyst. Additionally, during 12 h of test run, the HDS activity of the promoted catalyst was about 60% higher than MoS₂ one.     

红景天苷分子结构与光谱的密度泛函理论分析

随着科学技术不断发展，中药质量控制和质量评价出现了越来越多的新技术。在中药标准化过程中，现代药学研究已经取得了许多令人瞩目的成果，检测方法和技术取得了很大的进展，由过去单一指标检测发展到多指标检测，但由于中草药成分复杂，作用机制不明等因素制约了中药的发展。红景天是一种少数民族药，是中医药发展不可或缺的组成部分。红景天苷是红景天中的主要有效成分之一，其提取、分离和纯化等方法报道甚多，但其分子键长键角二面角、前线轨道分布、表面静电势等分子参数却鲜有报道，这些都是决定其化学性质和反应机理的重要因素。采用Gaussian09W化学计算软件的密度泛函理论DFT/B3LYP方法和6-31(d)基组优化红景天苷分子，得到其稳定结构的键长、键角和二面角参数。在此稳定构型的基础上，计算其表面静电势（ESP）、最低空轨道（LUMO）、最高占据轨道（HOMO）、红外光谱（IR）和核磁共振波谱数据（NMR）。分别对IR和NMR峰位置进行了归属并与文献报道数据进行了对比，结果表明：计算结果的红外吸收频率没有出现虚频说明该优化结果是合理可靠的，最高占据轨道能量E=-5.82 eV，最低空轨道能量E=-0.000 42 eV，二者差值为5.81 eV。通过绘制了轨道的电子云分布图可以看出HOMO轨道主要分布于苯环，为π电子的成键轨道有一个节面；LUMO轨道也主要分布在苯环上，为π电子的反键轨道有两个节面。表面静电势的绘制可以直观地反映出分子中哪部分易发生亲核取代、哪部分易发生亲电取代反应。通过绘制第一激发态和基态电子差值，可以直观地得到电子的迁移方向。对红景天苷分子计算理论研究可以为进一步探索其化学反应机理、结构修饰和活性位点的确认等提供重要的参考依据和新思路。