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81.
Sergey A. Krasnikov Sergey I. Bozhko Kevin Radican Olaf Lübben Barry E. Murphy Sundar-Raja Vadapoo Han-Chun Wu Mohamed Abid Valery N. Semenov lgor V. Shvets 《Nano Research》2011,4(2):194-203
The growth and ordering of C60 molecules on the WO2/W(110) surface have been studied by low-temperature scanning tunnelling microscopy and spectroscopy (STM and STS), low-energy
electron diffraction (LEED), and density functional theory (DFT) calculations. The results indicate the growth of a well-ordered
C60 layer on the WO2/W(110) surface in which the molecules form a close-packed hexagonal structure with a unit cell parameter equal to 0.95 nm.
The nucleation of the C60 layer starts at the substrate’s inner step edges. Low-temperature STM of C60 molecules performed at 78 K demonstrates well-resolved molecular orbitals within individual molecules. In the C60 monolayer on the WO2/W(110) surface, the molecules are aligned in one direction due to intermolecular interaction, as shown by the ordered molecular
orbitals of individual C60. STS data obtained from the C60 monolayer on the WO2/W(110) surface are in good agreement with DFT calculations. 相似文献
82.
Hichem Mallek Corinne Jegat Nathalie Mignard Majdi Abid Souhir Abid Mohamed Taha 《应用聚合物科学杂志》2013,129(3):954-964
Poly(ε‐caprolactone) (PCL)‐based thermoreversible networks with self‐healing properties were prepared through Diels–Alder (DA) and retro‐DA reactions. Bis‐ or Tris‐maleimide compounds and a series of copolymer(caprolactone‐diene) PCLXFY (X: degree of polymerization and Y: furan‐average functionality) with Y between 2.4 and 4.9 were used. The successive sequences of formation and dissociation of polycaprolactone networks via DA and retro‐DA reactions were observed repeatedly by dynamic mechanical analyses (DMA) and their gel‐temperatures determined. The cross‐linking densities, thermal properties, and thermal reversibility of the PCLXFY/multimaleimide polymers have been modulated by the structure and functionalities of the used diene and dienophile moieties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
83.
Abdul LATIF Xiangjun XIN Aftab HUSSAIN Liu BO Yousaf KHAN Ashiq HUSSAIN Abid MUNIR 《中国光电子学前沿》2012,(3)
We proposed an arrayed waveguide granting (AWG) based 10 Gbps full duplex wavelength division multiplexing passive optical network (WDM-PON) utilizing a retum-to-zero differential phase shift keying (R... 相似文献
84.
Aamir D. Abid 《Combustion and Flame》2009,156(10):1862-17251
A burner-stabilized, stagnation flame technique is introduced. In this technique, a previously developed sampling probe is combined with a water-cooled circular plate such that the combination simultaneously acts as a flow stagnation surface and soot sample probe for mobility particle sizing. The technique allows for a rigorous definition of the boundary conditions of the flame with probe intrusion and enables less ambiguous comparison between experiment and model. Tests on a 16.3% ethylene-23.7% oxygen-argon flame at atmospheric pressure show that with the boundary temperatures of the burner and stagnation surfaces accurately determined, the entire temperature field may be reproduced by pseudo one-dimensional stagnation reacting flow simulation using these temperature values as the input boundary conditions. Soot particle size distribution functions were determined for the burner-stabilized, stagnation flame at several burner-to-stagnation surface separations. It was found that the tubular probe developed earlier perturbs the flow and flame temperature in a way which is better described by a one-dimensional stagnation reacting flow than by a burner-stabilized flame free of probe intrusion. 相似文献
85.
Zinatizadeh AA Mohamed AR Abdullah AZ Mashitah MD Hasnain Isa M Najafpour GD 《Water research》2006,40(17):3193-3208
In this study, the interactive effects of feed flow rate (QF) and up-flow velocity (V up) on the performance of an up-flow anaerobic sludge fixed film (UASFF) reactor treating palm oil mill effluent (POME) were investigated. Long-term performance of the UASFF reactor was first examined with raw POME at a hydraulic loading rate (HRT) of 3 d and an influent COD concentration of 44300 mg/l. Extreme reactor instability was observed after 25 d. Raw POME was then chemically pretreated and used as feed. Anaerobic digestion of pretreated POME was modeled and analyzed with two operating variables, i.e. feed flow rate and up-flow velocity. Experiments were conducted based on a central composite face-centered design (CCFD) and analyzed using response surface methodology (RSM). The region of exploration for digestion of the pretreated POME was taken as the area enclosed by the feed flow rate (1.01, 7.63 l/d) and up-flow velocity (0.2, 3 m/h) boundaries. Twelve dependent parameters were either directly measured or calculated as response. These parameters were total COD (TCOD) removal, soluble COD (SCOD) removal, effluent pH, effluent total volatile fatty acid (TVFA), effluent bicarbonate alkalinity (BA), effluent total suspended solids (TSS), CH4 percentage in biogas, methane yield (Y M), specific methanogenic activity (SMA), food-to-sludge ratio (F/M), sludge height in the UASB portion and solid retention time (SRT). The optimum conditions for POME treatment were found to be 2.45 l/d and 0.75 m/h for QF and V up, respectively (corresponding to HRT of 1.5 d and recycle ratio of 23.4:1). The present study provides valuable information about interrelations of quality and process parameters at different values of the operating variables. 相似文献
86.
The synthesis of N‐heteroaryl(trifluoromethyl)hydroxyalkanoic acid esters by solid acid‐catalyzed Friedel–Crafts hydroxyalkylation of indoles and pyrroles with ethyl 3,3,3‐trifluoropyruvate and ethyl 4,4,4‐trifluoroacetoacetate is described. The inexpensive and readily available K‐10 montmorillonite is found to be an efficient catalyst for the synthesis of a wide variety of trifluoromethylated indol‐3‐yl‐ and pyrrol‐2‐yl‐hydroxypropionic and ‐butanoic acid esters. Using a series of substituted indoles and pyrroles the corresponding products were isolated in excellent yield (up to 98%) and 100% selectivity under mild experimental conditions, during very short reaction times. Beyond these, the ease of product isolation, catalyst stability and handling make this process an attractive, environmentally benign alternative for the synthesis of the target compounds. 相似文献
87.
Muhammad Ajmal Saad Anwar Hina Naeem Muhammad Abid Zia Muhammad Siddiq 《Polymer Engineering and Science》2020,60(11):2918-2929
This work narrates the synthesis of poly (acrylic acid) hydrogel microparticles (PAAHMPs), fabrication of silver nanoparticles (AgNPs) inside the structure of the prepared PAAHMPs and catalytic applications of PAAHMPs fabricated with AgNPs (PAAHMPs/AgNPs). The PAAHMPs were prepared by inverse suspension polymerization technique while fabrication of AgNPs was carried out by chemical reduction method using sodium borohydride (NaBH4) as reducing agent. The identification of functional groups in bare PAAHMPs and in the PAAHMPs/AgNPs composite system was carried out by the Fourier transform infrared spectroscopy. The size and morphology of the prepared hydrogel and its composite was studied by scanning electron microscopy and transmission electron microscopy. X-ray diffraction and thermal gravimetric analyzer was also used to characterize the bare PAAHMPs and PAAHMPs/AgNPs composite. The prepared PAAHMPs/AgNPs composite was used as catalyst for the reduction of nitro aromatic pollutants and an industrial dye, that is, 4-Nitrophenol (4-NP), 2-Nitrophenol (2-NP) and methyl orange. No loss in catalytic activity was noted in seven consecutive cycles of recycling process while only 37.5% loss in catalytic activity was observed upon storing the catalyst for 90 days. 相似文献
88.
Massimiliano S. Tagliamonte Nabil Abid Stefano Borocci Elisa Sangiovanni David A. Ostrov Sergei L. Kosakovsky Pond Marco Salemi Giovanni Chillemi Carla Mavian 《International journal of molecular sciences》2021,22(1)
Our evolutionary and structural analyses revealed that the severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2) spike gene is a complex mosaic resulting from several recombination events. Additionally, the fixation of variants has mainly been driven by purifying selection, suggesting the presence of conserved structural features. Our dynamic simulations identified two main long-range covariant dynamic movements of the novel glycoprotein, and showed that, as a result of the evolutionary duality, they are preserved. The first movement involves the receptor binding domain with the N-terminal domain and the C-terminal domain 2 and is maintained across human, bat and pangolin coronaviruses. The second is a complex network of long-range dynamics specific to SARS-CoV-2 involving the novel PRRA and the conserved KR*SF cleavage sites, as well as conserved segments in C-terminal domain 3. These movements, essential for host cell binding, are maintained by hinges conserved across human, bat, and pangolin coronaviruses glycoproteins. The hinges, located around Threonine 333 and Proline 527 within the N-terminal domain and C-terminal domain 2, represent candidate targets for the future development of novel pan-coronavirus inhibitors. In summary, we show that while recombination created a new configuration that increased the covariant dynamic movements of the SARS-CoV-2 glycoprotein, negative selection preserved its inter-domain structure throughout evolution in different hosts and inter-species transmissions. 相似文献
89.
90.
The available data of crude oil viscosity over a temperature range 130-220°F and at atmospheric pressure are used to develop a method to predict the viscosity of crude oils. The proposed correlation based upon API gravity, and viscosity at reservoir temperature. The proposed new correlation has been verified using data base on crude oil of different densities, and it shows significantly better correlation, with an average absolute deviation (AAD) of 2.8%. 相似文献