Synthesis and Antimycobacterial Evaluation on Arylsulfonyl and Arylcarbonyl Derivatives of Ofloxacin

Four ofloxacin derivatives 3, 5, 6 , and 11 were found to exhibit > 90% inhibition on the growth of M. tuberculosis at a concentration of 6.25 μg/mL. Compounds 3, 5 and 11 have also exhibited a broad spectrum of antibacterial activities while 8‐fluoro‐3‐methyl‐9‐[4‐(4‐nitrophenylsulfonyl)piperazin‐1‐yl)‐6‐oxo‐2,3‐dihydro‐6H‐1‐oxo‐3a‐azaphenalene‐5‐carboxylic acid ( 6 ), which exhibited potent activity against the growth of TB with the MIC of 2.23 μg/mL and a selectivity index (SI) of > 14.80, was inactive against the growth of G(+)‐ and G(‐)‐bacteria. Selective anti‐TB activity was achieved by the introduction of an arylsulfonyl group at C‐7 piperazin‐4‐yl of N‐demethyl ofloxacin. Compound 6 is species‐specific, exhibiting no significant activity against the growth of bacterial species other than M. tuberculosis, which implied the possibility of developing new specific anti‐TB drug candidates without inducing cross resistance with other currently used antibacterial drugs. Structural optimization of 6 is on‐going.     

Using a Fuzzy Piecewise Regression Analysis to Predict the Nonlinear Time-Series of Turbulent Flows with Automatic Change-Point Detection

Research has already shown that turbulent flow consists of some coherent time- and space-organized vortical structures. Some dynamic systems and experimental models are employed to understand the turbulent generation mechanism. However, these approaches still cannot provide a good nonlinear analysis of turbulent time-series. In the real turbulent flow, very complicated nonlinear behaviors, which are affected by many vague factors are present. Based on the nonlinear behavior and the results of from this traditional research, we introduce multivariate statistical analysis of an experimental study to explain practical phenomenon. In this paper, a new approach of fuzzy piecewise regression analysis with automatic change-point detection is proposed to predict the nonlinear time-series of turbulent flows. In order to show the practicality and usefulness of this model, we present an example of predicting the near-wall turbulence time-series as a verifiable model. The results of practical applications show that the proposed method is appropriate and appears to be useful in nonlinear analysis and in fuzzy environments to predict the turbulence time-series. This revised version was published online in July 2006 with corrections to the Cover Date.     

Anion‐ and Solvent‐Induced Assembly and Reversible Structural Transformation of d10‐Metal Coordination Architectures Containing N‐(4‐(4‐Aminophenyloxy)phenyl)isonicotinamide

We set out studies on anion‐ and solvent‐induced assembly based on the ligand N‐(4‐(4‐aminophenyloxy)phenyl)isonicotinamide (papoa), which is synthesized to show a bent and flexible backbone. Reactions of papoa with ZnX₂ (X=Cl, Br, and I) gave the dinuclear macrocycles ([ZnX₂(papoa)]₂; X=Cl ( 1 a ), Br ( 2 a ), I ( 3 )), the structure of which was determined by X‐ray diffraction. Notably, the less bulky Cl and Br compounds afforded the coordinated imine in acetone (i.e., [ZnX₂(papoi)]₂, papoi=N‐(4‐(4‐(propan‐2‐ylideneamino)phenoxy)phenyl)isonicotinamide; X=Cl ( 1 b ), Br ( 2 b )), whereas the iodine one only gave the coordinated amine compound 3 under the same reaction condition. In fact, the coordinated imine can return to the amine analogue upon exposure to air or in DMSO, which has been monitored by ¹H NMR spectroscopy and powder X‐ray diffraction. Both the dinuclear [Zn(papoa)(NO₃)₂]₂ ( 4 a ) and the 1D [Zn(papoa)₂(NO₃)₂]_n ( 4 b ) were formed from the reaction of Zn(NO₃)₂ and papoa in mixed solvents with acetone and acetonitrile, respectively. In addition, Cd(ClO₄)₂ can react with papoa to give the 1D framework {[Cd(papoa)₂(CH₃CN)₂](ClO₄)₂}_n ( 5 a ) and the 2D framework [Cd(papoa)₂(ClO₄)₂]_n ( 5 b ), depending on the solvent used, that is, MeOH and CH₃CN, respectively. Importantly, the 1D framework with axially coordinated CH₃CN molecules and the 2D framework with axially coordinated ClO₄^? ions can be interconverted by heating and grinding in the presence of CH₃CN, respectively. Such a reversible structural transformation process was proven by PXRD studies.     

The abnormal direct-current resistivity of Ni–Mn–Ni triple-layered magnetic thin-films and their magnetic wall observations

We have observed an abnormal electron transport characteristic from the Ni–Mn–Ni triple-layered magnetic thin-films. Due to the intercalated Mn ultra-thin interlayer, the magnetic domain structure and the electron transport characteristic differ a lot from their original magnetic (Fe, Co, and Ni) films. As inspected by a magnetic force microscopy (MFM), we observed the variation of the domain configuration with Mn interlayer thicknesses (for 1, 5, and 10 nm). Moreover, we also examined and found that the direct current (DC) resistivity have no significant change as the current conducts from the current-in-wall (CIW) to the current- perpendicular-to-wall (CPW), which are opposite to the results of single layered films.     

Analysis on DFB laser diode with main and multiple side modes injection-locked

One distributed feedback (DFB) laser diode with main and multiple side modes injection-locked is proposed and demonstrated. DFB laser diode can be successfully injection-locked not only in the main mode but also in the side modes. The side mode suppression ratio (SMSR) value of each injection-locked mode is enhanced, thereby, it can be a promising candidate for the use of multiple optical sources. Our proposed scheme has the potential to be used as optical sources for radio-on-wavelength division multiplexing (WDM) transport systems to provide multiple services.     

Reversible Phase Transformation and Luminescence of Cadmium(II)–Dipyridylamide‐Based Coordination Frameworks

We have synthesized a series of 1D double‐zigzag ({[Cd(paps)₂(H₂O)₂](ClO₄)₂}_n ( 1 ), {[Cd(papo)₂(H₂O)₂](ClO₄)₂}_n ( 3 ), and {[Cd(papc)₂(H₂O)₂](ClO₄)₂}_n ( 5 )) and 2D polyrotaxane frameworks ([Cd(papc)₂(ClO₄)₂]_n ( 6 )) by the reaction of Cd(ClO₄)₂ with dipyridylamide ligands N,N′‐bis(pyridylcarbonyl)‐4,4′‐diaminodiphenyl thioether (paps), N,N′‐bis(pyridylcarbonyl)‐4,4′‐diaminodiphenyl ether (papo), and N,N′‐(methylenedi‐p‐phenylene)bispyridine‐4‐carboxamide (papc), respectively, where their molecular structures have been determined by X‐ray diffraction studies. Based on the powder X‐ray data (PXRD) of compound 3 and its Zn^II analogue, heating the double‐zigzag framework of compound 3 can give the polyrotaxane framework of [Cd(papo)₂(ClO₄)₂]_n ( 4 ) and grinding this powder sample in the presence of moisture resulted in its complete conversion back into the pure double‐zigzag framework. In addition, heating the double‐zigzag frameworks of compounds 1 and 5 can induce structural transformation into their respective polyrotaxanes, whereas grinding these solid samples in the presence of moisture did not lead to the formation of the double zigzags. Herein, we investigated the effect of the metal (from Zn^II to Cd^II) on the assembly process and luminescence properties, as well as on the particularly intriguing structural transformation of a series of papx‐based frameworks. In fact, the assembly behavior and luminescence properties of the Cd^II? papx and Zn^II? papx frameworks were really similar. However, both Zn^II? papx (x=s, o) frameworks can perform reversible structural transformation, but only the Cd^II? papo framework can do it. Therefore, a delicate metal effect on such a new structural transformation can be observed.     

Using oppositely charged ions to operate a three-station [2]rotaxane in two different switching modes

A [2]rotaxane undergoes switching of its bis-p-xylyl-[26]crown-6 (BPX26C6) component away from its guanidinium station toward its 2,2'-bipyridyl and carbamate stations upon the addition and removal of Zn(2+) and PO(4)(3-) ions, respectively.     

Optical Resolution of 5‐Oxo‐1‐Phenyl‐Pyrazolidine‐3‐Carboxylic Acid as a New Organocatalyst for Organic Reactions

Optical resolution of racemic 5‐oxo‐1‐phenyl‐pyrazolidine‐3‐carboxylic acid 2 with L‐amino acid methyl ester via the diastereomers formation was investigated. Treatment of racemic 5‐oxo‐1‐phenyl‐pyrazolidine‐3‐carboxylic acid 2 with L‐valine methyl ester gave diastereomers with a total yield of 86%. The diastereomeric dipeptides can be easily separated by flash column chromatography. Acidic cleavage of the derived diastereomers gave both the optically pure (+)‐(R)‐ and (‐)‐(S)‐5‐oxo‐1‐phenyl‐pyrazolidine‐3‐carboxylic acid ((+)‐(R)‐ 2 and (‐)‐(S)‐ 2 ) with a total yield of 94% and 95%, respectively.     

HDTV/Gigabit Ethernet over bidirectional WDM-PON based on injection-locked Fabry-Perot laser diodes

Bidirectional high definition television (HDTV)/Gigabit Ethernet over wavelength-division-multiplexing (WDM)-passive optical network (PON) based on injection-locked Fabry-Perot laser diodes (FP LDs) as transmitters were proposed and demonstrated. Injection-locked FP LDs, a particularly inexpensive option, are used to replace conventional distributed feedback (DFB) LDs. Services with 77 HDTV channels and 1 Gigabit Ethernet channel connection were successfully demonstrated over 40 km single-mode fiber (SMF) transport. Good performance of bit error rate (BER) and clear eye diagram were achieved in our proposed bidirectional WDM-PON.