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71.
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73.
Seyed Hossein Hendi Fereshteh Azari Ebrahim Rahimi Mina Elahi Zahra Owjifard Zahra Armanfard 《Annalen der Physik》2020,532(10):2000162
It is known that scalar-tensor gravity models can be studied in Einstein and Jordan frames. In this paper, a model of scalar-tensor gravity in Einstein's frame is considered to calculate the Lifshitz-like black hole solutions with different horizon topologies. Thermodynamic properties and first order van der Waals-like phase transition are studied, and it is found that the Lifshitz parameter affects the phase structure. In addition, thermal stability is investigated by using the behavior of heat capacity and various methods of geometrical thermodynamics. 相似文献
74.
Ilaria D'Auria Marina Lamberti Mina Mazzeo Stefano Milione Claudio Pellecchia 《Journal of polymer science. Part A, Polymer chemistry》2014,52(1):49-60
New aluminum alkyl complexes, supported by o‐phenylene‐derived phosphido diphosphine pro‐ligands [Ph‐PPP]‐H and [iPr‐PPP]‐H ([Ph‐PPP]‐H = bis(2‐diphenylphosphinophenyl)phosphine; [iPr‐PPP]‐H = bis(2‐diisopropylphosphinophenyl)phosphine) are reported. Compounds [Ph‐PPP]AlMe2 ( 1 ), [iPr‐PPP]AlMe2 ( 2 ), and [Ph‐PPP]AliBu2 ( 3 ) have been synthesized by reaction of the pro‐ligand with the appropriate trialkyl aluminum precursor and have been characterized by 1H, 13C and 31P NMR spectroscopy. The solution NMR data and theoretical calculations suggest for all complexes trigonal bipyramidal structures with C2v symmetry in which the phosphido diphosphine ligand acts as a κ3 coordinated ligand. All complexes promote the ring‐opening polymerization of ε‐caprolactone, L‐ and rac‐lactide. Polyesters with controlled molecular parameters (Mn, end groups) and low polydispersities are obtained. Upon addition of isopropanol, efficient binary catalytic systems for the immortal ring‐opening polymerization of the cyclic esters are produced. Preliminary investigations show the ability of these complexes to promote copolymerization of l ‐lactide and ?‐caprolactone to achieve copolymers whose microstructures are depending on the structure of the catalyst. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 49–60 相似文献
75.
Amirhassan?AmiriEmail authorView authors OrcID profile Mehdi?Baghayeri Mina?Sedighi 《Mikrochimica acta》2018,185(8):393
A magnetic sorbent was fabricated by coating the magnetized graphene oxide with polystyrene (PS) to obtain a sorbent of the type GO-Fe3O4@PS. The chemical composition and morphology of the sorbent were characterized. The sorbent was employed for the enrichment of polycyclic aromatic hydrocarbons (PAHs) from water samples. Various parameters affecting the enrichment were investigated. The PAHs were then quantified by gas chromatography with flame ionization detection. Linear responses were found in the range of 0.03–100 ng mL?1 for naphthalene and 2-methylnaphthalene, and of 0.01–100 ng mL?1 for fluorene and anthracene. The detection limits (at an S/N ratio of 3) range between 3 and 10 pg mL?1. The relative standard deviations (RSDs) for five replicates at three concentration levels (0.05, 5 and 50 ng mL?1) of analytes ranged from 4.9 to 7.4%. The method was applied to the analysis of spiked real water samples. Relative recoveries are between 95.8 and 99.5%, and RSD% are <8.4%. 相似文献
76.
A new method for multi-component synthesis of 1,4-dihydropyridine derivatives (1,4-DHPs) in the presence of meglumine supported on multiwalled carbon nanotubes (MWCNTs@meglumine) as a new heterogeneous, highly efficient and reusable catalyst was investigated. The reaction was performed under ultrasonic irradiation in EtOH at room temperature. A new, highly efficient heterogeneous catalyst, short reaction times, high to excellent yield of products, and safe and clean conditions are the advantages of the presented method. 相似文献
77.
H. K. Barrenscheen Margarete Frey F. Feigl L. T. Fairhall M. Settimj D. Ganassini A. Necke H. Müller Ch. Badham H. B. Taylor G. Moillère F. Weyrauch St. Litzner F. Grendel N. Schoorl H. Begemann A. Berat G. Widmark B. Vahlquist E. M. P. Widmar S. L. Oerskov J. P. Gregersen P. Iversen H. W. Mook D. D. van Sluke W. M. Kirjan W. C. Stadie E. C. Ross K. Lang H. Waelsch Gertrud Klepetar I. St. Lorant L. Kopetz J. W. Heim W. W. Práwdicz-Neminski Z. Babitsch J. F. Reith Th. von Fellenberg R. G. Turner Mina Z. Weeks A. Castille V. Henri 《Analytical and bioanalytical chemistry》1934,98(3-4):147-160
78.
Tafazzoli M Ghiasi M Moridi M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(2):350-357
Erigeroside was extracted from Satureja khuzistanica Jamzad (Marzeh Khuzistani in Persian, family of lamiaceae), and (1)H, (13)C, (13)C{(1)H}, (1)H-(1)H COSY, HMQC and J-HMBC were obtained to identify this compound and determine a complete set of J-coupling constants ((1)J(C-H), (2)J(C-H), (3)J(C-H) and (3)J(H-H)) values within the exocyclic hydroxymethyl group (CH(2)OH) and anomeric center. In parallel, density functional theory (DFT) using B3LYP functional and split-valance 6-311++G** basis set has been used to optimized the structures and conformers of erigeroside. In all calculations solvent effects were considered using a polarized continuum (overlapping spheres) model (PCM). The dependencies of (1)J, (2)J and (3)J involving (1)H and (13)C on the C(5')-C(6') (omega), C(6')-O(6') (theta) and C(1')-O(1') (phi) torsion angles in erigeroside were computed using DFT method. Complete hyper surfaces for (1)J(C1',H1'), (2)J(C5',H6'R), (2)J(C5',H6'S), (2)J(C6',H5'), (3)J(C4',H6'R), (3)J(C4',H6'S) and (2)J(H6'R-H5'S) as well as (3)J(H5',H6'R) were obtained and used to derive Karplus equations to correlate these couplings to omega, theta and phi. These calculated J-couplings are in agreement with experimental values. These results confirm the reliability of DFT calculated coupling constants in aqueous solution. 相似文献
79.
Dr. Lun An Patricia De La Torre Dr. Peter T. Smith Dr. Mina R. Narouz Prof. Christopher J. Chang 《Angewandte Chemie (International ed. in English)》2023,62(5):e202209396
We present a supramolecular approach to catalyzing photochemical CO2 reduction through second-sphere porosity and charge effects. An iron porphyrin box ( PB ) bearing 24 cationic groups, FePB-2(P) , was made via post-synthetic modification of an alkyne-functionalized supramolecular synthon. FePB-2(P) promotes the photochemical CO2 reduction reaction (CO2RR) with 97 % selectivity for CO product, achieving turnover numbers (TON) exceeding 7000 and initial turnover frequencies (TOFmax) reaching 1400 min−1. The cooperativity between porosity and charge results in a 41-fold increase in activity relative to the parent Fe tetraphenylporphyrin ( FeTPP ) catalyst, which is far greater than analogs that augment catalysis through porosity ( FePB-3(N ), 4-fold increase) or charge (Fe p-tetramethylanilinium porphyrin ( Fe-p-TMA ), 6-fold increase) alone. This work establishes that synergistic pendants in the secondary coordination sphere can be leveraged as a design element to augment catalysis at primary active sites within confined spaces. 相似文献
80.
In this study density functional theory (DFT) calculations at B3LYP/6-31G(d), B3LYP/6-31+G(d) and B3LYP/6-311+G(2df,2p) levels for geometry optimization and total energy calculation were applied for investigation of the important energy-minimum conformations and transition-state of 1,2-, 1,3-, and 1,4-dithiepanes. Moreover, ab initio calculations at HF/6-31G(d) level of theory for geometry optimization and MP2/6-311G(d)//HF/ 6-31G(d) level for a single-point total energy calculation were reported for different conformers. The obtained results reveal that, the twist-chair conformer is a global minimum for all of these compounds. Also, two local minimum were found in each case, which are twisted-chair and twisted-boat conformers. The boat and chair geometries are transition states. The minimum energy conformation of 1,2-dithiepane is more stable than the lowest energy forms of 1,3-dithiepane and 1,4-dithiepane. Furthermore, the anomeric effect was investigated for 1,3-dithiepane by the natural bond orbital method. The computational results of this study shows that all conformers of 1,3-dithiepane have a hypercojugation system. Finally, the 13C NMR chemical shifts for the conformers of 1,4-dithiepane were calculated, which have good correlation with their experimental values. 相似文献