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41.
Mazhar Iqbal Muhammad Nasir Khan Ayaz Arif Khan Imran Zaka Amjad Mehmood Ikhtiar Ahmad 《Journal of Superconductivity and Novel Magnetism》2018,31(11):3535-3544
We present an extensive study of the magnetic properties of a novel La0.5Ba0.5MnO3 perovskite material prepared by the hydrothermal method. The explored sample was structurally studied by the x-ray diffraction (XRD) method which confirms the formation of a pure cubic phase of a perovskite structure with Pm3m space group. The magnetic properties were probed by employing temperature M (T) and external magnetic field M (μoH) dependence of magnetization measurements. A magnetic phase transition from ferromagnetic to paramagnetic phase occurs at 339 K in this sample. The maximum magnetic entropy change (\(\left | {{\Delta } S}_{M}^{\max } \right |\)) took a value of 1.4 J kg??1 K??1 at the applied magnetic field of 4.0 T for the explored sample and has also been found to occur at Curie temperature (TC). This large entropy change might be instigated from the abrupt reduction of magnetization at TC. The magnetocaloric effect (MCE) is maximum at TC as represented by M (μoH) isotherms. The relative cooling power (RCP) is 243.2 J kg??1 at μoH =?4.0 T. Moreover, the critical properties near TC have been probed from magnetic data. The critical exponents δ, β, and γ with values 3.82, 0.42, and 1.2 are close to the values predicted by the 3D Ising model. Additionally, the authenticity of the critical exponents has been confirmed by the scaling equation of state and all data fall on two separate branches, one for T < TC and the other for T > TC, signifying that the critical exponents obtained in this work are accurate. 相似文献
42.
Waleed Ahmad Khattak Mazhar Ul-Islam Joong Kon Park 《Korean Journal of Chemical Engineering》2012,29(11):1467-1482
This study was conducted to evaluate the presence, origination and classification of various hydrolyzing enzymes from malt and their specified hydrolyzing effects on various substrates for bioethanol production and to link these characteristics with the future prospects of bioethanol production. These enzymes are categorized as cell wall, starch, protein, lipid, polyphenol and thiol hydrolyzing enzymes based on their substrate specificity. Waste from beer fermentation broth (WBFB) has been evaluated as a rich source of malt derived hydrolyzing enzymes with significant self potential for bioethanol production. However, yeast cells cannot survive at the high temperature required for the saccharification activities of hydrolyzing enzymes during simultaneous saccharification and fermentation (SSF). This dilemma might be resolved by bioethanol production at elevated temperatures via cell-free fermentation systems in the presence of malt hydrolyzing enzymes. Moreover, emerging technologies such as genetic engineering in biomass and biotransformation in cell-free enzymatic systems will likely hasten bioethanol production in the near future. The present study adds new dimensions to eco-friendly bioethanol production from renewable and waste energy resources based on the specific hydrolyzing activities of malt enzymes. 相似文献
43.
This contribution describes a parallel approach for determining the collision state of a large collection of ellipsoids. Collision detection is required in granular dynamics simulation where it can combine with a differential variational inequality solver or discrete element method to approximate the time evolution of a collection of rigid bodies interacting through frictional contact. The approach proposed is structured on three levels. At the lowest level, the collision information associated with two colliding ellipsoids is obtained as the solution of a two-variable unconstrained optimization problem for which first and second order sensitivity information is derived analytically. Although this optimization approach suffices to resolve the collision problem between any two arbitrary ellipsoids, a less versatile but more efficient approach precedes it to gauge whether two ellipsoids are actually in contact and require the more costly optimization approach. This intermediate level draws on the analytical solution of a 3rd order polynomial obtained from the characteristic equation of two arbitrary ellipsoids. Finally, this intermediate level is invoked by the outer level only when a 3D spatial binning algorithm indicates that two ellipsoids share the same bin (box) and therefore could potentially collide. This multi-level approach is implemented in parallel and when executed on a ubiquitous Graphics Processing Unit (GPU) card scales linearly and yields a two orders of magnitude speedup over a similar algorithm executed on the Central Processing Unit (CPU). The GPU-based ellipsoid contact detection algorithm yields a 14-fold speedup over a CPU-based sphere contact detection algorithm implemented in the third party open source Bullet Physics Library (BPL). The proposed methodology provides the efficiency demanded by granular dynamics applications, which routinely handle scenarios with millions of collision events. 相似文献
44.
A new method based on the cloud point extraction(CPE) for separation and proconcentration of nickei(Ⅱ) and its subsequent determination by graphite furnace atomic absorption spectrometry(GFAAS) was proposed, 8-hydroxyquinoline and Triton X-100 were used as the ligand and surfactant respectively. Nickel(Ⅱ) can form a hy- drophobic complex with 8-hydroxyquinoline, the complex can be extracted into the small volume surfactant rich phase at the cloud point temperature(CPT) for GFAAS determination. The factors affecting the cloud point extraction, such as pH, ligand concentration, surfactant concentration, and the incubation time were optimized. Under the optimal conditions, a detection limit of 12 ng/L and a relative standard deviation(RSD) of 2.9% were obtained for Ni(Ⅱ) determination. The enrichment factor was found to be 25. The proposed method was successfully applied to the determination of nickel(Ⅱ) in certified reference material and different types of water samples and the recovery was in a range of 95%-103%. 相似文献
45.
Sumaira Zeeshan Sumera Javeed Kashif Yaqub Mazhar MehmoodSohail Ahmad Janjua Shoaib Ahmad 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(10):1097-1102
We report the ablation of fullerite films deposited on metallic substrates with 3 keV electron pulses generated in a specially designed pulsed discharge tube. During ablation the fragmented species were detected by emission spectroscopy. The emission spectra of C2 and C1∗ (CII) provide the signatures of C60 fragmentation. The vibrational temperature of the C2 emitted from the ablated fullerite is ∼12,700 ± 1160 K compared with ∼18,230 ± 1150 K for the graphite sample under similar conditions. The fullerite films were produced by vacuum sublimation on Aluminum, Iron and Copper substrates and characterized by Atomic force microscope, X-ray diffraction; Raman and Fourier transform infrared spectroscopy. The comparisons of electron ablation of fullerite films with that of graphite show the similarities and differences of carbon bonding in the caged structure of C60 with that of the planar graphene sheets of graphite. 相似文献
46.
Khan NA Cone JW Pellikaan WF Khan MA Struik PC Hendriks WH 《Journal of the science of food and agriculture》2011,91(6):1041-1049
BACKGROUND: The stage of maturity at harvest has a major effect on the fatty acid (FA) content and composition of forage plants consumed by dairy cows. The present study investigated the dynamics of FA content and composition in stover (leaves and stem) and ears (cob, shank and husks) of two maize genotypes (G2 and G6) grown on sandy and clay soils and harvested at 14, 42, 56, 70 and 84 days after flowering (DAF). In addition, the FA content and composition of six maize genotypes (G1‐G6) grown on the two soil types were compared at the normal harvest time of early genotypes in the Netherlands (70 DAF). RESULTS: The contents of total FAs and major individual FAs in both stover and ears changed significantly (P < 0.001) during the grain‐filling period (14‐84 DAF). In stover the contents of C16:0, C18:2, C18:3 and total FAs declined (P < 0.001) while those of C18:0 and C18:1 increased (P < 0.001) with progressive grain filling. The rate of decline in C18:3 and total FA contents was slower during 14‐56 DAF as compared with 56‐84 DAF. In ears, the contents of C16:0, C18:1, C18:2 and total FAs increased up to 56 DAF and then remained more or less constant until 84 DAF. At 70 DAF the content of polyunsaturated fatty acids (PUFAs) in both stover and ears did not differ among the six genotypes. However, the average contents of C16:0, C18:3 and total FAs in stover were higher (P < 0.05) on clay soil, whereas those of C18:0 and C18:1 were higher on sandy soil. CONCLUSION: The results demonstrate that the maximum PUFA content in silage maize is harvested around 56 DAF, in the present study at a Tsum of 927 °C.d or at an ear dry matter content of 440 g kg?1, which is before the onset of rapid senescence. Any further delay in harvesting will cause a rapid decline in C18:3 content in maize silages. Copyright © 2011 Society of Chemical Industry 相似文献
47.
Nasrullah Shah Jung Hwan Ha Mazhar Ul-Islam Joong Kon Park 《Korean Journal of Chemical Engineering》2011,28(9):1936-1944
Molecularly imprinted polymer (MIP) submicron/nanoscale beads selective for L-Phenylalanine (L-Phe) and D-Phe as well as non-imprinted
beads were prepared by modified suspension polymerization involving agitation of the reaction mixture at high rotation speed
under safe radical conditions. The effects of pH, template and concentration of racemate solution on the performance of the
phenylalanine (Phe) imprinted polymeric submicron/nanoscale beads were studied. L-Phe-imprinted submicron/nanoscale beads
prepared for the first time by modified suspension polymerization showed enhanced adsorption capacity and selectivity over
those of D-Phe imprinted and non-imprinted beads. Maximum adsorption capacity, 0.35 mg/g, and selectivity, 1.62, of L-Phe
imprinted submicron/nanoscale beads were higher than the adsorption capacities, 0.30 and 0.19mg/g, and selectivities, 1.59
and 1.02, of D-Phe imprinted and nonimprinted submicron/nanoscale beads, respectively. FE-SEM analyses revealed that L- and
D-Phe imprinted beads were larger (100 nm–1.5 μm) than non-imprinted nanobeads (100–800 nm). 13C CP-MAS NMR spectroscopy helped in correlating the bead sizes and the extent of reaction during polymerization. Similarly,
FT-IR study was used for evaluation of structural characteristics of the prepared Phe-imprinted and non-imprinted beads. The
preparation of Phe-imprinted submicron/nanoscale beads with improved adsorption and separation properties and the study of
effect of template on the size and performance of the prepared beads are suitable from both economical and research point
of view in MIP field. 相似文献
48.
49.
Syed Tajammul Hussain Farzana Zia M. Mazhar 《European Food Research and Technology》2009,228(5):799-806
We report an interesting finding that the catalytic performance of supported Ni/γ-Al2O3 catalyst towards selective catalytic hydrogenation of edible oils can be greatly enhanced by pretreatment of the γ-Al2O3 support before catalyst preparation. Calcination of Al2O3 at appropriate temperatures results in the highly dispersive nano Ni/γ-Al2O3 catalyst and thus improves the catalytic performance. Catalyst sample of improved physical properties prepared by modified
procedure using γ-Al2O3 as support was characterized using powder XRD, SEM, BET, FTIR, Particle size analyzer, CO-chemisorption, and TPR studies.
These studies indicate that support pretreatment results in enhancing catalyst dispersion with increase in Ni loadings. Clearly
the effect of surface area and particle size of the catalyst coupled with surface properties and method of catalyst preparation
on the saturated fats content of the foods like margarines prevails. 相似文献
50.
Nawazish A. Khan Rehana Begum Mazhar Mehmood 《Journal of Superconductivity and Novel Magnetism》2010,23(3):351-359
A reproducible synthesis and characterization of Zn-doped Cu0.5Tl0.5Ba2Ca2Cu3−y
Zn
y
O12−δ
(y=0, 0.5, 1.0, 1.5) superconductors at a relatively lower synthesis temperature of 840°C are studied by using X-ray diffraction,
resistivity, ac-susceptibility and FTIR absorption measurements. The X-ray diffraction (XRD) studies of these samples have
shown a tetragonal structure in which the c-axis length has been found to decrease with increased Zn doping. The critical temperature and magnitude of diamagnetism have
not been significantly affected with the doping of Zn at this synthesis temperature. The magnitude of diamagnetism in the
as-prepared undoped samples is decreased, whereas it remains stable (unchanged) in oxygen post-annealed samples. The apical
oxygen phonon’s modes of type Tl–OA–M(2) and Cu(1)–OA–M(2) {where M=Cu/Zn} and the planar oxygen phonon modes of type M(2)–OP–M(2) are also softened with the increase of Zn doping. We interpreted the softening of these oxygen related phonon modes
linked with the decreased c-axis length, reduced John–Teller distortions and increased mass of Zn (65.38 amu) as compared to that of Cu (63.54 amu) (Kaplan
et al., Phys. Rev. B 65, 214509, 2002). 相似文献