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81.
A series of novel 6H‐1,3,5‐oxathiazine S,S‐dioxides were synthesized by the m‐CPBA oxidation (2.2 equiv) of 6H‐1,3,5‐oxathizines. The synthetic utilities of the newly synthesized cyclic sulfones were investigated. In a thermal condition, compounds 6H‐1,3,5‐oxathiazine S,S‐dioxides were found relatively stable, but Lewis acid‐induced thermal reaction afforded the corresponding amides. The plausible pathway to amides from 6H‐1,3,5‐oxathiazine S,S‐dioxides was also discussed in this account. 相似文献
82.
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84.
We generated a series of new polymer-bound peroxo complexes of vanadium(V) and molybdenum(VI) of the type [VO(O(2))(2)(sulfonate)]-PSS [PSS = poly(sodium 4-styrene sulfonate)] (PV(3)), [V(2)O(2)(O(2))(4)(carboxylate)VO(O(2))(2)(sulfonate)]-PSSM [PSSM = poly(sodium styrene sulfonate-co-maleate)] (PV(4)), [Mo(2)O(2)(O(2))(4)(carboxylate)]-PA [PA = poly(sodium acrylate)] (PMo(1)), [MoO(O(2))(2)(carboxylate)]-PMA [PMA = poly(sodium methacrylate)] (PMo(2)), and [MoO(O(2))(2)(amide)]-PAm [PAm = poly(acrylamide)] (PMo(3)) by reacting V(2)O(5) (for PV(3) and PV(4)) or H(2)MoO(4) (for PMo(1), PMo(2), and PMo(3)) with H(2)O(2) and the respective water-soluble macromolecular ligand at pH 5-6. The compounds were characterized by elemental analysis (CHN and energy-dispersive X-ray spectroscopy), spectral studies (UV-vis, IR, (13)C NMR, (51)V NMR, and (95) Mo NMR), thermal (TGA) as well as scanning electron micrographs (SEM), and EDX analysis. It has been demonstrated that compounds retain their structural integrity in solutions of a wide range of pH values and are approximately 100 times weaker as substrate to the enzyme catalase relative to H(2)O(2), its natural substrate. The effect of the title compounds, along with previously reported compounds [V(2)O(2)(O(2))(4)(carboxylate)]-PA (PV(1)) and [VO(O(2))(2)(carboxylate)]-PMA (PV(2)) on rabbit intestine alkaline phosphatase (ALP) has been investigated and compared with the effect induced by the free diperoxometallates viz. Na[VO(O(2))(2)(H(2)O)] (DPV), [MoO(O(2))(2)(glycine)(H(2)O)] (DMo(1)), and [MoO(O(2))(2)(asparagine)(H(2)O)] (DMo(2)). It has been observed that although all the compounds tested are potent inhibitors of the enzyme, the polymer-bound and neat complexes act via distinct mechanisms. Each of the macromolecular compounds is a classical noncompetitive inhibitor of ALP. In contrast, the action of neat pV and heteroligand pMo compounds on the enzyme function is consistent with a mixed type of inhibition. 相似文献
85.
Heteroaromatic oligomer 5,7,12,14-tetrachloro-6,13-diazapentacene (TCDAP) was characterized and assessed as n-channel material in field-effect transistor applications. A single-crystal transistor based on TCDAP as the channel material exhibits a very high electron mobility of 3.39 cm(2) V(-1) s(-1) and an on/off ratio of ~1.08 × 10(4) respectively. 相似文献
86.
Abdulla-Al-Mamun M Kusumoto Y Zannat T Islam MS 《Physical chemistry chemical physics : PCCP》2011,13(47):21026-21034
The photocatalytic and plasmonic photothermal cancer cell-killing activity of the metallic Au-capped TiO(2) (Au@TiO(2)) composite colloidal nanopellets has been investigated on HeLa cells under UV-visible (350-600 nm) light irradiation. The Au@TiO(2) composite nanopellets with the uniform Au-capped TiO(2) structure were successfully synthesized by simple reduction of HAuCl(4) on the surface of TiO(2) nanoparticles. The morphological structure and surface properties of Au@TiO(2) were characterized by using UV-visible absorption spectroscopy, TEM, SEM, XPS, EDX and XRD analyses. The formation of hydroxyl radicals (˙OH) was confirmed by photoluminescence (PL) spectra. The photocatalytic and photothermal cell-killing activity of the Au@TiO(2) nanopellets was found to vary with the molar ratio of Au to TiO(2). The direct involvement of the metal particles in mediating the electron transfer from the photoexcited TiO(2) under the band gap excitation is considered to carry out the efficient photocatalytic reaction on the cells. The plasmonic absorption spectra of Au@TiO(2) suspensions were also measured for the evaluation of photothermal cell killing. The charge separation, the interfacial charge-transfer and photothermal activity promoted the photocatalytic-photothermal cancer-cell killing more than TiO(2) alone. The cytotoxic effect of Au@TiO(2) nanopellets with low concentration of gold (TiO(2) : Au molar ratio > 1 : 1) was found to be 100%, whereas that of the commercial TiO(2) (P25) was ca. 50%. The comparative study of the cell viability using Au alone and TiO(2) alone revealed that the synergistic effect of photocatalytic hydroxyl radical formation and Au-plasmonic photothermal heat generation plays a vital role in the cancer cell killing. A plausible mechanism was also proposed for photocatalytic cancer cell killing based on the obtained results. 相似文献
87.
Zinad DS Shaaban KA Abdalla MA Islam MT Schüffler A Laatsch H 《Natural product communications》2011,6(1):45-48
Four isocoumarins have been isolated from the terrestrial Streptomyces sp. ANK302, namely 6,8-dimethoxy-3-methylisocoumarin (1), 6,8-dihydroxy-3-methylisocoumarin (2), 6,8-dihydroxy-7-methoxy-3-methylisocoumarin (3), and 6,7,8-trimethoxy-3-methylisocoumarin (4). Compound 1 is a new naturally-occurring isocoumarin, and 2 was isolated as a new bacterial product. The structures 1-4 were deduced from high resolution mass, 1D and 2D NMR spectra and by comparison with related compounds from the literature. Compound 2 showed a strong zoosporicidal activity at a concentration of 5 microg/mL against a phytopathogenic oomycete, Plasmopara viticola, and 1 was active against 相似文献
88.
Matthew Monari Ombaba V. J. Logeeswaran M. Saif Islam 《Applied Physics A: Materials Science & Processing》2013,111(1):251-259
In this paper we report a novel application of electrically conductive film (ECF) of Ag sub-micron particles that includes both isotropic and anisotropic film technologies in providing simultaneous electrical contact and mechanical anchor between fracture transfer-printed (1-D) single crystal semiconductor micro- and nano-pillars and a carrier substrate. We assembled silver sub-micron particles (AgSP) monolayers with varying particle diameters and investigated their optical and electrical characteristics prior to their incorporation into thermoplastic polymers. It was found that transfer-printing of the Si micropillar arrays, into electrically conductive thermoplastic receiver substrates, made of films of AgSP/PMMA blends atop metallic substrates could be effectively achieved to yield electrically interfaced 1-D Si micropillar arrays with retention of their orientation and integrity according to the SEM images. The carrier substrate can potentially be reused to generate additional Si micropillar arrays that can be similarly harvested. 相似文献
89.
M. Samiul Islam Sarker Takahiro Nakamura Yuliati Herbani Shunichi Sato 《Applied Physics A: Materials Science & Processing》2013,110(1):145-152
Many late transition binary alloy nanoparticles (NPs) have been fabricated through a wide variety of techniques. Various steps are involved in the fabrication of such NPs. Here, we used a simple and green route to fabricate solid-solution Rh–Pd and Rh–Pt bimetallic alloy NPs through femtosecond laser irradiation in a solution without any chemicals like reducing agents. X-ray diffraction (XRD) peaks of NPs obtained in the solutions with different ratios of Rh–Pd and Rh–Pt ions monotonically varied from the position of pure Rh to those of Pd and to Pt which respectively indicated that these NPs were alloy. Composition of fabricated NPs was fully tuned over the entire range of Rh1?x –Pd x , and Rh1?x –Pt x with varying the mixing ratio of metal ions in the solution. Studies of Rh–Pd and Rh–Pt solid-solution system suggest that the alloy formation occurs through the nucleation of Rh and then followed by the diffusion of Rh, Pd and Rh, Pt to form a homogeneous alloy. The variety of average size of the alloy NPs for different compositions could be attributed to different reduction rate and surface energies of metal ions. Our result implies that femtosecond laser irradiation in aqueous solution is one of the potential methodologies to form multimetallic solid-solution alloy NPs with fully tunable composition. 相似文献
90.
G.Y. Jung W. Wu S. Ganapathiappan D.A.A. Ohlberg M. Saif Islam X. Li D.L. Olynick H. Lee Y. Chen S.Y. Wang W.M. Tong R.S. Williams 《Applied Physics A: Materials Science & Processing》2005,81(7):1331-1335
We summarize our key developments in nanoimprint lithography (NIL) that employs a single layer resist lift-off process: lowering of the imprint temperature (for thermal imprint) and pressure, achieving uniform resist thickness and low residual resist layer thickness in the trenches, and eliminating metal ‘rabbit ears’ for the single-layer lift-off. In thermal NIL, our requirements for lower operating temperature and pressure motivated us to develop an alternative resist that is a viscous fluid at room temperature and cures at a lower temperature of 70 °C than the operating temperature of the conventional thermal NIL (≈200 °C). For UV NIL, we devised a method to dispense the resist onto a hydrophobic mold and use the hydrophilic substrate surface to spread the resist via surface wetting to engineer a continuous and uniform film. We also explored the use of Si(110) substrates as molds to produce features with perfectly vertical side walls, and the use of aqua regia to directly etch away rabbit ears. PACS 86.65.+h; 81.16.Nd; 81.16.Rf 相似文献