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61.
H. Ahmad M. Z. Zulkifli A. A. Latif K. Thambiratnam S. W. Harun 《Laser Physics》2009,19(12):2188-2193
In this paper, we propose and demonstrate a stable Brillouin-Erbium Fibre Laser (BEFL) capable of generating up to 17 lasing
wavelengths in the Short-Wave length (S-band) region. The proposed setup uses a 7.7 km Dispersion Compensating Fibre (DCF)
to act as a non-linear gain medium and a 30 m long Depressed-Cladding Erbium Doped Fibre (DC-EDF) as an optical amplifier
for amplification in the S-band region. The proposed BEFL has an optimum tuning range of 1499 to 1502 nm and is capable of
generating 17 lasing wavelengths with peak powers of between −20 to −15 dBm when injected with a Brillouin Pump (BP) of 5
dBm at 1499 nm and a Raman Pump (RP) of 300 mW at 1420 nm. 相似文献
62.
For familial aggregation of a binary trait, one method that has been used is the GEE2 (generalized estimating equation) method
corresponding to a multivariate logit model. We solve the complex estimating equations for the GEE2 method using an automatic
differentiation software which computes the derivatives of a function numerically using the chain rule of the calculus repeatedly
on the elementary operations of the function. Based on this, we are able to show in a simulation study that the GEE2 estimates
are quite close to the maximum likelihood estimates assuming a multivariate logit model, and that the GEE2 method is computationally
faster when the dimension or family size is larger than four. 相似文献
63.
Umar Farooq Rizvi Hamid Latif Siddiqui Saeed Ahmad Matloob Ahmad Masood Parvez 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(10):o547-o549
Molecules of (E)‐3‐(2‐chloro‐6‐methylquinolin‐3‐yl)‐1‐(5‐iodo‐2‐thienyl)prop‐2‐en‐1‐one, C17H11ClINOS, (I), and (E)‐3‐(2‐chloro‐6‐methylquinolin‐3‐yl)‐1‐(5‐methyl‐2‐furyl)prop‐2‐en‐1‐one, C18H14ClNO2, (II), adopt conformations slightly twisted from coplanarity. Both structures are devoid of classical hydrogen bonds. However, nonclassical C—H...O/N interactions [with C...O = 3.146 (5) Å and C...N = 3.487 (3) Å] link the molecules into chains extended along the b axis in (I) and form dimers with an R22(8) motif in (II). The structural analysis of these compounds provides an insight into the correlation between molecular structures and intermolecular interactions in compounds for drug development. 相似文献
64.
p,p′-Dichloro-, p,p′-dimethyl- and p,p′-dimethoxybenzophenone hydrazones react with tetrachloro- and tetrabromo-o-benzoquinone to give directly the halogenated benzodioxoles (IIIa-IIIf), respectively, together with the corresponding tetrahalocatechol. Cleavage of the dioxole ring by nucleophilic reagents depends markedly on the nature of the substituents. The dimethoxyderivatives (IIIc) and (IIIf) proved to be unusually reactive toward cleavage by dilute mineral acids, lithium aluminum hydride, hydrazines and malonitrile, whereas the dichloro analog behaves normally and is not cleaved under the same conditions. 相似文献
65.
Two new oxazolidinone polycyclitols, 4,5,7,8,9-pentahydroxy-3-tosyldecahydronaphtho [2,1-d]oxazol-2(9bH)-one and 4,5,6,7,8-pentahydroxy-3-tosyldecahydronaphtho [2,1-d]oxazol-2(9bH)-one were synthesized starting from p-benzoquinone. An endo selective Diels–Alder cycloaddition between p-benzoquinone and 1-acetoxybutadiene followed by stereoselective reduction with NaBH4–CeCl3·7H2O led to the formation of an allylic cis-diol. The obtained diols were protected with p-TsNCO to yield bis-carbamates and then a palladium-catalyzed ionization/cyclization reaction produced two oxazolidinone derivatives. Oxidation of the two double bonds in either oxazolidinones with OsO4 followed by acetylation produced oxazolidinone-pentaacetates whose exact configurations were determined by X-ray diffraction analysis. Controlled removal of the acetate groups furnished the desired two new oxazolidinone polycyclitols. 相似文献
66.
Fawi M. Abd El Latif 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):267-274
Abstract Novel 2-cyanomethylbenzimid-(thi)-azole-2,2-dicarboxaldehydes were prepared in quantitative yields and reacted easily with o-aminophenol derivatives to yield new multi-functionallized ox-, thi- and diazepine derivatives in one-pot reaction. 相似文献
67.
Polymers are crucial component for modern sensor devices. However, comprehensive research on polymer sensor technology is still going strong. Molecular imprinted membrane (MIM) is a great design that demonstrates acceptable recognition ability when integrated with a sensing transducer. Generally, the detection technique that has been widely and sparingly used for pesticide is mass spectrometry merged with gas and/or liquid chromatography. Nevertheless, this review focuses not on these common methods but on the specific methodology of MIM biosensor for the analysis of pesticides. Finally, the transduction schemes of the MIM sensor are reviewed. The interest of this article is sketched to the trends and challenges present in this field of study. 相似文献
68.
Copper, one of the most significant metals, is exposed to IR radiation. A Nd:YAG laser (1064 nm, 1.1 MW, 12 ns) has been used to irradiate fine polished and annealed samples (4 N, 1×1×0.3 cm3) with 100 laser shots under a vacuum of ~10?6 torr. The laser focal spot size and power density on the target were 12 μm and 3×1012 Wm?2 respectively. The surface and structural studies were performed by analyzing scanning electron micrographs and X-ray diffractograms (XRDs), respectively. Laser ablation results in boiling, splashing, hydrodynamical sputtering and exfoliation along with other relevant phenomena. The XRD patterns of the exposed sample indicate a change in diffraction intensity and grain sizes. The atomic planes remain undisturbed for the irradiated target. The information collected is useful for investigating the complexities found in radiation–metal interactions. 相似文献
69.
Latif U Rohrer A Lieberzeit PA Dickert FL 《Analytical and bioanalytical chemistry》2011,400(8):2457-2462
Titanate sol–gel layers imprinted with carbonic acids were used as sensitive layers on quartz crystal microbalance. These
functionalized ceramics enable us detection of volatile organic compounds such as ethanol, n-propanol, n-butanol, n-hexane, n-heptane, n-/iso-octane, and n-decane. Variation of the precursors (i.e., tetrabutoxy titanium, tetrapropoxy titanium, tetraethoxy titanium) allows us to
tune the sensitivity of the material by a factor of 7. Sensitivity as a function of precursors leads to selective inclusion
of n-butanol vapors down to 1 ppm. The selectivity of materials is optimized to differentiate between isomers, e.g., n- and iso-octane. The results can be rationalized by correlating the sensor effects of hydrocarbons with the Wiener index.
A mass-sensitive sensor based on titanate layer was also developed for monitoring emanation of degraded engine oil. Heating
the sensor by a meander avoids vapor condensation. Thus, a continuously working oil quality sensor was designed. 相似文献
70.
Abdul Latif Afrah A.N. Abdou 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(4):1436-1444
We introduce some notions of generalized nonlinear contractive maps and prove some fixed point results for such maps. Consequently, several known fixed point results are either improved or generalized including the corresponding recent fixed point results of Ciric [L.B. Ciric, Multivalued nonlinear contraction mappings, Nonlinear Anal. 71 (2009) 2716-2723], Klim and Wardowski [D. Klim, D. Wardowski, Fixed point theorems for set-valued contractions in complete metric spaces, J. Math. Anal. Appl. 334 (2007) 132-139], Feng and Liu [Y. Feng, S. Liu, Fixed point theorems for multivalued contractive mappings and multivalued Caristi type mappings, J. Math. Anal. Appl. 317 (2006) 103-112] and Mizoguchi and Takahashi [N. Mizoguchi, W. Takahashi, Fixed point theorems for multivalued mappings on complete metric spaces, J. Math. Anal. Appl. 141 (1989) 177-188]. 相似文献