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71.
Amit Kumar S. M. Yusuf J. V. Yakhmi 《Applied Physics A: Materials Science & Processing》2010,99(1):79-83
We have synthesized nanoparticles of Cu1.5[Cr(CN)6]⋅6.5H2O of varying size by using poly(vinylpyrrolidone) (PVP) as a protecting polymer. The particle size variation has been achieved
by varying the amount of the PVP surfactant with the reactants. The prepared nanoparticles have been investigated by using
X-ray diffraction, transmission electron microscopy, and direct-current magnetization techniques. The nanoparticles crystallize
in a face centred cubic structure (space group: Fm3m). The approximate particle sizes for the three samples are 18, 9, and
5 nm, respectively. Non-PVP nanoparticles (18 nm) show a magnetic ordering temperature of 65 K. A decrease in the magnetic
ordering temperature was observed with decreasing particle size. These nanoparticles are magnetically very soft, showing negligibly
small values of the coercivity and remanent magnetization. The maximum magnetization and spontaneous magnetization values
at 5 K are found to decrease with decreasing particle size. The observed magnetization behaviour of the nanoparticles has
been attributed to the increasing surface spin disorder with decreasing particle size. 相似文献
72.
Yusuf Z. Umul 《Optics & Laser Technology》2010,42(8):1323-1327
The paraxial wave equation is a reduced form of the Helmholtz equation. Its solutions can be directly obtained from the solutions of the Helmholtz equation by using the method of complex point source. We applied the same logic to quantum mechanics, because the Schrödinger equation is parabolic in nature as the paraxial wave equation. We defined a differential equation, which is analogous to the Helmholtz equation for quantum mechanics and derived the solutions of the Schrödinger equation by taking into account the solutions of this equation with the method of complex point source. The method is applied to the problem of diffraction of matter waves by a shutter. 相似文献
73.
Mohd Yusuf Khan Xiangxiong Chen Seung Woo Lee Seok Kyun Noh 《Macromolecular rapid communications》2013,34(15):1225-1230
Atom transfer radical polymerization (ATRP) catalyzed by high oxidation state metal salts of FeX3 is developed for the first time in the absence of both external initiator and reducing agent. Methyl methacrylate (MMA) and styrene are polymerized successfully using FeX3/Phosphorous ligands with well‐controlled molecular weight distributions (=1.5). The molecular weight of the polymers increases with monomer consumption with the progress of time and the polymerization behaviors show a decent ATRP trend. Activators and initiators are suggested to generate in situ by the addition reaction of MMA and one equivalent of FeX3. The PMMA synthesized from without‐initiator system is characterized by 1H, 13C and DEPT (distortionless enhancement by polarization transfer nuclear magnetic resonance) nuclear magnetic resonance spectroscopy. Chain extension and copolymerization experiments prove the livingness of the obtained polymer.
74.
D. K. Aswal A. Singh C. Thinaharan S. M. Yusuf C. S. Viswanadham G. L. Goswami 《哲学杂志》2013,93(28):3181-3191
The temperature and field dependences of in-plane (IP) and out-of-plane (OP) anisotropic magnetoresistances (AMRs) have been measured in La1 ? x Pb x MnO3 (LPMO) thin films having different microstructures, namely the single-crystal (SC), nanocrystalline (NC) and polycrystalline (PC) microstructures. The OP AMR, irrespective of the microstructure, is found to be considerably larger than the IP AMR. The magnetization data show that the larger OP AMR arises because magnetization is favoured in the film plane owing to strain anisotropy. In addition, the temperature and field dependences of both IP and OP AMRs are governed by the crystallinity of the films, indicating that the AMRs are strongly influenced by the magnetization process. 相似文献
75.
Tapas Debsharma Yusuf Yagci Helmut Schlaad 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(51):18663-18666
The unsaturated bicyclic acetal levoglucosenyl methyl ether was readily obtained from sustainable feedstock (cellulose) and polymerized by cationic ring‐opening polymerization to produce a semicrystalline thermoplastic unsaturated polyacetal with relatively high apparent molar mass (up to ca. 36 kg mol?1) and decent dispersity (ca. 1.4). The double bonds along the chain can undergo hydrogenation and thiol–ene reactions as well as crosslinking, thus making this polyacetal potentially interesting as a reactive functional material. 相似文献
76.
One of the major problems in amperometric biosensors based on detection of H2O2 produced by enzymatic reaction between oxidase enzymes and substrate is the interference of redox active compounds such as ascorbic acid (AA), dopamine (DA) and uric acid (UA). To minimize these interferences, sodium bismuthate was used for the first time as an insoluble pre‐oxidant in the flow injection (FI) amperometric glucose biosensor at a Glucose oxidase (GOx) immobilized Pt/Pd bimetallic modified pre‐anodized pencil graphite electrode (p.PGE). In this context, these interfering compounds were injected into a flow injection analysis (FIA) system using an injector which was filled with NaBiO3. Thus, these interferents were converted into their redox inactive oxidized forms before reaching the electrode in the flow cell. While glucose was not influenced by the pre‐oxidant in the injector, the huge oxidation peak currents of the interferents decreased significantly in the biosensor. FI amperometric current time curves showed that the AA, DA and UA were minimized by 96 %, 86 %, and 98 % respectively, in the presence of an equivalent concentration of interferences in a 1.0 mM glucose solution. The proposed FI amperometric glucose biosensor exhibits a wide linear range (0.01–10 mM, R2=0.9994) with a detection limit of 2.4×10?3 mM. Glucose levels in the artificial serum and two real samples were successfully determined using the fabricated FI amperometric biosensor. 相似文献
77.
We report the results of the DC magnetization, neutron powder diffraction and neutron depolarization studies on the spin-chain
compounds Ca3Co2–x
Fe
x
O6 (x = 0, 0.1, 0.2 and 0.4). Rietveld refinement of neutron powder diffraction patterns at room temperature confirms the single-phase
formation for all the compounds in rhombohedral structure with space group Rc. Rietveld refinement also confirms that Fe was doped at the trigonal prism site, 6a (0, 0, 1/4) of Co. The high temperature
magnetic susceptibility obeys the Curie-Weiss law; the value of the paramagnetic Curie temperature (θ
p) decreases as the concentration of iron increases and it becomes negative for x = 0.4. No extra Bragg peak as well as no observable enhancement in the intensity of the fundamental (nuclear) Bragg peaks
has been observed in the neutron diffraction patterns down to 30 K. No depolarization of neutron beam has been observed down
to 3 K confirming the absence of ferro- or ferrimagnetic-like correlation.
相似文献
78.
N,N′‐diethoxy‐4,4′‐azobis(pyridinium) hexafluorophosphate (DEAP) has been synthesized by alkylation of the corresponding N‐oxide and characterized. DEAP exhibits UV induced cis–trans isomerization with absorptions at around λ = 459 and 360 nm, respectively. The ability of the DEAP ion to act as a photoinitiator for the cationic polymerization of cyclohexene oxide and N‐vinylcarbazole is demonstrated. The initiation step involves the decay of the excited state of the trans form of the salt with homolytic bond rupture of the nitrogen–oxygen bond. Its potential use as a photoinitiator for free radical polymerization is also demonstrated using methyl methacrylate monomer as the example.
79.
Baris Kiskan Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2014,52(20):2911-2918
In this work, a self‐healing strategy for poly(propylene oxide)s bearing coumarine‐benzoxazine units (PPO‐CouBenz)s based on light induced coumarine dimerization reactions is described. Four different types of poly(propylene oxide) amines with molecular weights ranging from 440 to 5000 Da were reacted with formaldehyde and 4‐methyl‐7‐hydroxycoumarin to yield desired (PPO‐CouBenz)s. The crosslinked polymer films were prepared by solvent casting of various compositions of PPO‐CouBenzs in chloroform followed by thermal ring opening reaction of benzoxazine groups at 210–240 °C. Thermal curing and thermal stability of the initial PPOs and final products were investigated. Using allyl benzoxazine in the formulation, it was demonstrated that the toughness of the films was improved. Photoinduced healing of coumarin‐based cured PPO‐CouBenz polymer films was investigated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2911–2918 相似文献
80.
Electrical and photoelectrical behaviour of heterojunctions based on novel oligomeric metal complexes 下载免费PDF全文
Metin Atlan Yusuf Selim Ocak Salih Pasa Hamdi Temel Ahmet Tombak Tahsin Kilicoğlu Kemal Akkilic Murat Aydemir 《应用有机金属化学》2015,29(12):798-804
Naringenin‐based Schiff base ligands with 4‐aminobenzoic hydrazide were obtained as a unilateral form ( L1 ). The ligand was oligomerized by oxidative polycondensation reaction with NaOCl as an oxidant in an aqueous alkaline medium at 90 °C to form a functional oligomer ( L2 ), and its transition metal complexes such as those with Cu(II), Ni(II) and Zn(II) were prepared. The monomer and the oligomeric compounds were characterized using various techniques. Optical and electrical properties of the complexes were also investigated. All compounds showed indirect band gaps and they can be accepted as being in the semiconductor class. Organic–inorganic hybrid devices were obtained using n‐Si inorganic semiconductor and the complexes. The characteristic parameters of the devices were determined using current–voltage (I–V) and capacitance–voltage measurements in the dark. Photoelectrical properties of the devices were investigated using I–V measurements under a solar simulator with an AM1.5 global filter. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献