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51.
Farida Benmouna Zohra Bouabdellah-Dembahri Mustapha Benmouna 《Journal of Macromolecular Science: Physics》2013,52(7):998-1008
The process of polymer synthesis based on polymerization-induced phase separation (PIPS) is revisited from the theoretical point of view. Cahn–Hilliard–Cook theories for spinodal decomposition are adapted to describe the kinetics of phase separation and deduce the time-resolved scattering function, while the double reaction model is used to describe the kinetics of polymerization. Coupling of these two kinetics is provided by the Carother's equation relating the fraction of reacted monomers to the degree of polymerization at time t, denoted N(t). It is argued that the approach to criticality is governed by a critical parameter, χc, that is different from the usual parameter for spinodal decomposition, χs, deduced from the second derivative of the free energy. While the latter parameter depends on the reciprocal degree of polymerization N?1(t), the former one depends on its time integral. This leads to significant consequences on the phase behavior developments during the PIPS process. Hydrodynamic interactions are found to speed up the emergence of instability modes. Although the qualitative trends remain similar to those of the Rouse dynamics, important quantitative changes are found due to the long-range viscous flow effects. 相似文献
52.
53.
Fatima Ijaz Syed Salman Shafqat Hafiz Adnan Ahamd Munawar Ali Munawar Misbahul Ain Khan 《Journal of heterocyclic chemistry》2019,56(4):1231-1238
Derivatives of ninhydrin are extensively used in the field of forensic sciences as important latent fingerprint reagents. Many works have been performed upon their synthesis and reactivity, but there are many spaces to work on the compounds of quinoline‐2,3,4(1H)‐triones—analogues of ninhydrin, in both dimensions: synthesis and reactivity, and according to the best of our knowledge, not a single detailed or short compiled article has been published for these compounds. This review briefly summarizes the chemistry of quinoline‐2,3,4(1H)‐triones. 相似文献
54.
Annemarie Marckwordt Fatima ElOuahabi Hadis Amani Sergey Tin Narayana V. Kalevaru Paul C. J. Kamer Sebastian Wohlrab Johannes G. deVries 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3524-3528
Use of ZrO2/SiO2 as a solid acid catalyst in the ring‐opening of biobased γ‐valerolactone with methanol in the gas phase leads to mixtures of methyl 2‐, 3‐, and 4‐pentenoate (MP) in over 95 % selectivity, containing a surprising 81 % of M4P. This process allows the application of a selective hydroformylation to this mixture to convert M4P into methyl 5‐formyl‐valerate (M5FV) with 90 % selectivity. The other isomers remain unreacted. Reductive amination of M5FV and ring‐closure to ?‐caprolactam in excellent yield had been reported before. The remaining mixture of 2‐ and 3‐MP was subjected to an isomerising methoxycarbonylation to dimethyl adipate in 91 % yield. 相似文献
55.
Dr. Jakob-Jonathan Maudrich Max Widemann Fatima Diab Ralf H. Kern Dr. Peter Sirsch Dr. Christian P. Sindlinger Dr. Hartmut Schubert Prof. Dr. Lars Wesemann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(70):16081-16087
Organodihydridoelement anions of germanium and tin were reacted with metallocene dichlorides of Group 4 metals Ti, Zr and Hf. The germate anion [Ar*GeH2]− reacts with hafnocene dichloride under formation of the substitution product [Cp2Hf(GeH2Ar*)2]. Reaction of the organodihydridostannate with metallocene dichlorides affords the reduction products [Cp2M(SnHAr*)2] (M=Ti, Zr, Hf). Abstraction of a hydride substituent from the titanium bis(hydridoorganostannylene) complex results in formation of cation [Cp2M(SnAr*)(SnHAr*)]+ exhibiting a short Ti–Sn interaction. (Ar*=2,6-Trip2C6H3, Trip=2,4,6-triisopropylphenyl). 相似文献
56.
Abdulmumeen A. Hamid Olapeju O. Aiyelaagbe Arvind S. Negi Fatima Kaneez Suaib Luqman Stephen O. Oguntoye 《Natural product research》2019,33(2):296-301
Chloroform extract from the leaves of Turraea vogelii Hook f. ex Benth demonstrated cytotoxic activity against a chronic myelogenous leukemia cell, K-562 with IC50 of 14.27 μg/mL, while chloroform, ethyl acetate and methanol extracts from the stem of the plant inhibited K-562 cells growth with IC50 of 19.50, 24.10 and 85.40 μg/mL respectively. Bioactive chloroform extract of Turraea vogelii leaves affords two triterpenoids: oleana-12,15,20-trien-3β-ol (1), and oleana-11,13-dien-3β,16α,28-triol (2), with six fatty esters, ethyl hexaeicos-5-enoate (3), 3-hydroxy-1,2,3-propanetriyltris(tetadecanoate) (4), 1,2,3-propanetriyl(7Z,7′Z,7′′Z)tris(-7-hexadecenoate) (5), 1,2,3-propanetriyl(5Z,5′Z,5′′Z)tris(-5-hexadecenoate) (6), 1,2,3-propanetriyltris(octadecanoate) (7), and 2β-hydroxymethyl tetraeicosanoate (8). Tetradecane (9), four fatty acids: hexadecanoic acid (10), tetradecanoic acid (11), (Z)-9-eicosenoic acid (12), and ethyl tetradec-7-enoate (13) were isolated from chloroform extract of Turraea vogelii stem. 1,2,3-propanetriyltris(heptadecanoate) (14), (Z)-9-octadecenoic acid (15) and (Z)-7-tetradecenoic acid (16) were isolated from ethyl acetate extract while (Z)-5-pentadecenoic acid (17) was obtained from methanol extract of the plant stem. Compounds 1, 2, 5, 6, 11, 12, 15, 16 and 17 exhibited pronounced antiproliferative activity against K-562 cell lines. 相似文献
57.
Muhammad Zafar Irshad Khan Syeda Saniya Zahra Madiha Ahmed Humaira Fatima Bushra Mirza Ihsan-ul Haq 《Natural product research》2019,33(14):2099-2104
Ipomoea carnea Jacq. is an important folklore medicinal plant, assessed for its underexplored biological potential. Antioxidant, cytotoxic, antiproliferative and polyphenolic profile of whole plant was evaluated using various techniques. Maximum extract recovery (29% w/w), phenolic [13.54 ± 0.27 μg GAE/mg dry weight (DW)] and flavonoid (2.11 ± 0.10 μg QE /mg DW) content were recorded in methanol-distilled water (1:1) flower extract. HPLC-DAD analysis quantified substantial amount of six different polyphenols ranging from 0.081 to 37.95 μg/mg extract. Maximum total antioxidant and reducing potential were documented in methanol-distilled water and acetone-distilled water flower extracts (42.62 ± 0.47 and 24.38 ± 0.39 μg AAE/mg DW) respectively. Ethanol-chloroform root extract manifested highest free radical scavenging (IC50 of 61.22 μg/mL) while 94.64% of the extracts showed cytotoxicity against brine shrimps. Ethanol leaf extract exhibited remarkable activity against THP-1 cell line (IC50 = 8 ± 0.05 μg/mL) and protein kinases (31 mm phenotype bald zone). 相似文献
58.
R. Hannachi S. Boussaïdi P. Teulet G. Taieb Y. Cressault A. Gleizes Zohra Ben Lakhdar 《Applied Physics A: Materials Science & Processing》2008,92(4):933-937
A spectroscopic study of the plasma plume created by a laser beam on the surface of NaCl aqueous solution is presented. Optical
emission spectra are recorded and temporally analyzed; electron number density is determined from the Stark broadening of
the NI nitrogen line, and temperature is obtained from relative intensity of OI oxygen lines. The intensity of an atomic line
from sodium was used to quantitate its molar percentage in the Oceanic and Mediterranean sea, and calibration curves have
been constructed for concentrations ranging up to 1.5%. 相似文献
59.
This study describes a synthesis of symmetric and dissymmetric bis[(perfluoroalkane)‐sulfonyl]imides by the reaction of the sodium salt of perfluoroalkanesulfonamide RFSO2NH−Na+ (RF = C4F9, C6F13, C8F17) with hexamethyldisilazane and perfluoroalkanesulfonylfluoride RFSO2F (RF = C4F9, C6F13, C8F17). They are obtained, in two steps, in moderate overall yield. Moreover, this paper provides a study of their inhibition on bovine carbonic anhydrase. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:542–548, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20452 相似文献
60.
Lachtar Zohra Khorief Nacereddine Abdelmalek Djerourou Abdelhafid 《Structural chemistry》2020,31(1):253-261
Structural Chemistry - The enantioselectivity of the oxazaborolidine-catalysed asymmetric reduction reaction of ketimine generated from acetophenone has been investigated by transition state theory... 相似文献