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21.
Mirosław Kwiatkowski 《Journal of mathematical chemistry》2017,55(10):1893-1902
The paper presents the results of research devoted to obtaining the low-cost activated carbon fibres from waste flax and jute cloth by carbonisation in inert atmosphere and activation with air as well as to the analysis of the microporous structure of materials obtained on the basis of the nitrogen, argon and benzene adsorption isotherms, using among others, the unique LBET method with implemented of the new models of the multilayer adsorption on the heterogeneous surfaces of the carbonaceous adsorbents. As part of the research conducted, imaging of the surface of the low-cost activated carbon fibres obtained has also been done using scanning electron microscopy. 相似文献
22.
23.
In [V.E. Viola et al., Phys. Rev. Lett. 93 (2004) 132701, D.S. Bracken et al., Phys. Rev. C 69 (2004) 034612] the observed decrease in spectral peak energies of IMFs emitted from hot nuclei was interpreted in terms of a breakup density that decreased with increasing excitation energy. Subsequently, Raduta et al. [Ad. Raduta et al., Phys. Lett. B 623 (2005) 43] performed MMM simulations that showed decreasing spectral peaks could be obtained at constant density. In this Letter we point out that this apparent inconsistency is due to a selective comparison of theory and data that overlooks the evolution of the fragment multiplicities as a function of excitation energy. 相似文献
24.
High peak power Nd:YAG laser pumped by 600-W diode laser stack 总被引:1,自引:0,他引:1
The Q-switched laser with triangle slab made of Nd:YAG crystal side pumped by 600-W quasi-cw diode laser stack has been designed. The multimode (M2≈2.6) output energy of about 42 mJ was demonstrated in free running mode for110-mJ pump energy. In Q-switch experiments, the KDDP Pockels cell was placed between the slab and rear mirror in plane-plane cavity with output coupler of 84% transmission. The energy of 8 mJ in 2.1-ns pulse duration was obtained for near TEM00 output beam. For passive Q-switching by means of Cr:YAG crystal of 12.6% unsaturated transmission, the energy of 5.1 mJ in 2.5-ns pulse duration was obtained for output beam close to TEM00 mode. 相似文献
25.
A Sandstr?m M Kwiatkowski J Chattopadhyaya 《Acta chemica Scandinavica. Series B: Organic chemistry and biochemistry》1985,39(4):273-290
A synthesis of a pentaribonucleotide fragment constituting the residues 59-63 of 3'-terminus of E. coli tRNAIle, 5'-ApGpUpCpC-3', has been carried out using a new, easily accessible and achiral 2'-ketal protecting group. The new 2'-ketal group has an additional advantage in that it is easily functionalized to the diamide with aqueous ammonia in the penultimate step of deblocking of fully protected oligoribonucleotides. Such a functionalization of the 2'-ketal group at the penultimate step of deblocking of the fully protected tRNA molecule enhances its relative rate of removal under an acidic condition with a minimum of damage of the target tRNA molecule. 相似文献
26.
A new pentadentate Schiff base 2,6,10-triaza-1,11-bis(2′-aminophenyl)-undeca-1,10-diene, abaDPT, and its complexes of general formula M(abaDPT)X2 where M = Cu(II), Ni(II), X = Cl, Br, I, NO3 and ClO4, have been prepared. The complexes have been characterized by electronic and IR spectra, EPR, magnetic moments, molar conductances, and elemental analysis. IR data show an interaction between halide anion of the outer coordination sphere and the complexed amino group. EPR and spectrophotometric data of most of the copper compounds are consistent with a distorted square pyramidal geometry. Single crystal EPR studies of Cu(abaDPT)(NO3)2 and Cu(abaDPT)Br2 revealed that copper atoms in the former compound occupy two magnetically inequivalent places in the lattice while copper atoms in the latter compound take identical sites. Principal g tensor axes of the two compounds have been determined. 相似文献
27.
I. Colon G. T. Kwiatkowski 《Journal of polymer science. Part A, Polymer chemistry》1990,28(2):367-383
This paper describes a totally new method for the formation of high molecular weight aromatic polymers. High molecular weight polyarylethersulfones are produced by nickel catalyzed coupling of aryl dichloride monomers. Metallic zinc is used to drive the polymerization reaction which takes place under relatively mild conditions in the presence of triphenylphosphine and a dipolar aprotic solvent. The versatility of the reaction is demonstrated, as well as the ability to provide a variety of high temperature polymers from readily available and inexpensive monomers. It is possible to use an integrated two-step process to produce aryl dichlorides from inexpensive aryl chlorides, and then to couple these directly to polymer without need for isolation and purification. This process resulted from a fundamental understanding of the chemistry and the use of statistically designed experiments to identify the important reaction parameters and to optimize the degree of polymerization. 相似文献
28.
Mirosław Kwiatkowski 《Adsorption》2008,14(1):37-53
The reported research is concerned with the properties of the new LBET class models designed to describe the heterogeneous
adsorption on microporous carbonaceous materials. In particular, the new adsorption models were applied to a computer analysis
of the microporous structure of two active carbons on the basis of argon and benzene adsorption isotherms. This paper provides
for more thorough information on the properties of the proposed models and identification technique presented in the earlier
papers. 相似文献
29.
Crystal Structures of Bacterial (6‐4) Photolyase Mutants with Impaired DNA Repair Activity 下载免费PDF全文
Kalinga Bowatte Dennis Kwiatkowski Esther Mittmann Heba Qasem Norbert Krauß Xiaoli Zeng Zhong Ren Patrick Scheerer Xiaojing Yang Tilman Lamparter 《Photochemistry and photobiology》2017,93(1):304-314
PhrB from Agrobacterium fabrum is the first prokaryotic photolyase which repairs (6‐4) UV DNA photoproducts. The protein harbors three cofactors: the enzymatically active FAD chromophore, a second chromophore, 6,7‐dimethyl‐8‐ribityllumazine (DMRL) and a cubane‐type Fe‐S cluster. Tyr424 of PhrB is part of the DNA‐binding site and could provide an electron link to the Fe‐S cluster. The PhrBY424F mutant showed reduced binding of lesion DNA and loss of DNA repair. The mutant PhrBI51W is characterized by the loss of the DMRL chromophore, reduced photoreduction and reduced DNA repair capacity. We have determined the crystal structures of both mutants and found that both mutations only affect local protein environments, whereas the overall fold remained unchanged. The crystal structure of PhrBY424F revealed a water network extending to His366, which are part of the lesion‐binding site. The crystal structure of PhrBI51W shows how the bulky Trp leads to structural rearrangements in the DMRL chromophore pocket. Spectral characterizations of PhrBI51W suggest that DMRL serves as an antenna chromophore for photoreduction and DNA repair in the wild type. The energy transfer from DMRL to FAD could represent a phylogenetically ancient process. 相似文献
30.