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991.
Microbial secondary metabolites (SMs) have long been viewed as a significant source of novel pharmaceutical and agrochemical molecules. With the increasing availability of genomic data, numerous biosynthetic gene clusters (BGCs) have been discovered. Despite the presence of tens of thousands of BGCs that can theoretically produce extremely diverse SMs, many gene clusters remain in a silent state under axenic culture conditions. Co‐culture is a promising research approach as it stimulates the expression of cryptic BGCs to produce novel metabolites and also mimics natural interspecies interactions in a laboratory environment. In recent years, the roles of SMs in microbial communication have caught the attention of researchers and our understanding of microbes and their production of remarkable SMs has improved. SMs may be extensively involved in a variety of communication events among microorganisms. We herein summarize certain representative findings in the field of chemical communication involving SMs in co‐culture systems. 相似文献
992.
Nobuaki Kitazawa Masami Aono Yoshihisa Watanabe 《Journal of Physics and Chemistry of Solids》2011,72(12):1467-1471
This paper describes the synthesis and characterization of organic–inorganic layered perovskite compounds, (CnH2n+1NH3)2PbI4 (n=4, 5, 7, 8 and 9). The effect of the number of carbon atoms on luminescence properties has been examined. Thin films of microcrystalline (CnH2n+1NH3)2PbI4 fabricated by spin-coating are highly oriented, with the c-axis perpendicular to the substrate surface. Temperature-dependent optical absorption spectra reveal that (CnH2n+1NH3)2PbI4 films (n=4, 7, 8 and 9) show the structural phase transitions. The excitonic structures of (CnH2n+1NH3)2PbI4 vary with the number of carbon atoms of the alkyl chain length. At low temperatures below 100 K, the lowest-energy free-exciton band of (CnH2n+1NH3)2PbI4 (n=7, 8 and 9) split into three fine-structure levels. In contrast to (CnH2n+1NH3)2PbBr4 films, (CnH2n+1NH3)2PbI4 (n=7, 8 and 9) shows no triplet exciton emission, but it shows the Stokes-shifted emission from bound excitons. 相似文献
993.
Shintaro Nomura Masumi Yamaguchi Tatsushi Akazaki Hiroyuki Tamura Hideaki Takayanagi Yoshiro Hirayama 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):292
The electron–hole states in the fractional quantum Hall regime is investigated with a back-gated undoped quantum well by photoluminesccence in magnetic fields. The evolution of the photoluminescence spectra is discussed depending on the electron density. We find anomalies of the photoluminescence at the integer as well as the fractional filling factors. 相似文献
994.
In this contribution, we give a brief survey of some elementary many body processes observable at surfaces. We begin the survey by discussing how the electron ground state would behave and look like in real space at surfaces. Next, we discuss how these electrons behave when they are perturbed by external fields characterized by ultrashort time scales. We follow this with a discussion of how the dynamics of electrons would then affect the motion of adsorbates on surfaces. Finally, we cite some possible technological applications utilizing this knowledge. We also discuss possible trends or directions of scientific research in this century. 相似文献
995.
This paper is concerned with the initial value problem for semilinear systems of wave equations. First we show a global existence
result for small amplitude solutions to the systems. Then we study asymptotic behavior of the global solution. We underline
that ``modified' free profiles are obtained for all global solutions to the systems even in the case where the free profile
might not exist. Moreover, we prove non–existence of any free profiles for the global solution in some cases where the effect
of the nonlinearity is strong enough.
The first author was partially supported by Grant-in-Aid for Science Research (14740114), JSPS. 相似文献
996.
Both the amount of water and the number of calcium ions are main factors affecting the dissolution of chitin in calcium chloride dihydrate-saturated methanol (calcium solvent). The higher degree of N-acetylation of the chitin was also indicated by its higher solubility in calcium solvent. The chitin hydrogel was prepared by adding a large excess of water to the chitin solution with vigorous stirring, followed by extensive dialysis against water or by filtration to remove the methanol and calcium ions. The water content of the chitin hydrogel was approximately 94–96% (w/v) and could be controlled by centrifugation. The chitin gel was also prepared by the addition of a large excess of alcohol, such as ethanol and iso-propanol, and these protocols were found to be effective under anhydrous conditions because the alcohols were exchangeable with other organic solvents in solution. The chitin hydrogel was more susceptible to lysozyme than to chitinase, and showed and a poor susceptibility to chitosanase. A α-chitin-type crystalline structure was regenerated from chitin sheets prepared from both α-chitin and β-chitin solutions in calcium solvent, but the β-chitin-type sheet was formed from the β-chitin hydrogel prepared by mechanical agitation in water. The α-chitin hydrogel solidified when thawed after freezing, but the β-chitin hydrogel prepared by mechanical agitation maintained its gel form even after prolonged freezing. Animal studies revealed a low toxicity for the chitin sheet and an acceleration of epidermal cell regeneration. 相似文献
997.
To synchronize a control signal with a packet signal in response to changing timing jitter, we investigate ultra-short pulse tracking by using wavelength dispersion for a short-time optical buffer in an optical router. 相似文献
998.
Hideaki Sunagawa 《Journal of Differential Equations》2003,192(2):308-325
We consider the Cauchy problem for systems of cubic nonlinear Klein-Gordon equations with different mass terms in one space dimension. We prove some result concerning the global existence of small amplitude solutions and their asymptotic behavior. As a consequence, we see that the condition for small data global existence is actually influenced by the difference of masses in some cases. 相似文献
999.
Masahiko Taniguchi Hideaki Fujii Koichiro Oshima Kiitiro Utimoto 《Tetrahedron》1993,49(48):11169-11182
erythro-3-Hydroxy-2-methylpropionates or erythro-3-hydroxy-2-methylpropionamides were prepared with high stereoselectivity by NaBH4 reduction of the corresponding 2-methyl-3-oxo esters or 2-methyl-3-oxo amides in the presence of a catalytic amount of manganese(II) chloride. On the other hand, reduction of these substrates with n-Bu4NBH4 provided threo-isomers selectively. erythro-Selective reduction of 2-methyl-3-oxo amides with NaBH3CN in 1N HCl-MeOH is also described. 相似文献
1000.