A novel and convenient approach for the solid-phase 5'-functionalization of oligonucleotides is proposed in this article. The approach is based on the activation of free 5'-hydroxyl of polymer ...support-bound protected oligonucleotides by
,
'-disuccinimidyl carbonate followed by interaction with amino-containing ligands. Novel amino-containing derivatives of
-dodecaborate, estrone, cholesterol, and α-tocopherol were specially prepared. A wide range of oligonucleotide conjugates bearing
-dodecaborate, short peptide, pyrene, lipophilic residues (cholesterol, α-tocopherol, folate, estrone), aliphatic diamines, and propargylamine were synthesized and characterized to demonstrate the versatility of the approach. The developed method is suitable for the conjugate synthesis of oligonucleotides of different types (ribo-, deoxyribo-, 2'-
-methylribo-, and others).
We present novel polyethylene (PE) composites for electromagnetic interference (EMI) shielding application. They are based on cobalt modified multi-walled carbon nanotubes (MWCNTs) produced via in ...situ polymerization of ethylene, with the Ti-Ziegler–Natta catalyst preliminarily immobilized on Co/MWCNT hybrids. The electromagnetic properties of the composites were tuned by varying the filler loading and Co:MWCNT ratio. The microstructure of the composites and electromagnetic absorption process were carefully characterized by transmission and scanning electron microscopy, X-ray diffraction, vibrating sample magnetometry, ferromagnetic resonance and vector network analysis. The electromagnetic wave absorbing properties of the nanocomposite were investigated in the 10 MHz−18 GHz frequency range revealing that the EMI absorption properties can be tuned by varying the Co:MWCNT weight ratio in the filler. Interestingly, the Co/MWCNT-PE composite with a total filler and Co loading of only 12 and 1.7 wt%, respectively, showed extremely high reflection loss (RL) of −55 dB. More importantly, an effective bandwidth of 12.8–17.8 GHz (RL below −10 dB) was achieved for a matching thickness of only 1.5 mm. The specific RL value (RL/filler loading) of the composite was superior in comparison with the previously reported nanostructured carbon materials. The highly effective absorbing properties of Co/MWCNT-PE composites are explained primarily by the unprecedented uniform filler distribution in the polyethylene as well as by the synergistic effect of MWCNTs and Co nanoparticles. This approach thus offered an effective strategy to design cost-effective, lightweight and flexible EMI shielding materials with tunable dielectric and magnetic performance.
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•New Co/MWCNT/polyethylene composites for EMI shielding applications were designed.•In situ polymerization ensured uniform distribution of Co/MWCNT filler in PE.•EMI shielding properties can be tuned by varying filler loading and Co:MWCNT ratio.•The effective bandwidth was 12.8–17.8 GHz at reflection loss below −10 dB.•Co/MWCNT/PE composite shows a minimum reflection loss value of −55 dB at 5.2 GHz.
A detailed study of the effect of reaction temperature, time, and cocatalyst composition on the ethylene polymerization performance of ...2-1-(2,6-dibenzhydryl-4-chlorophenylimino)ethyl-6-(1-mesityliminoethyl)pyridyliron dichloride (1) is reported. In the presence of modified methylaluminoxane (MMAO), 1 behaves like a highly active, “multisite-like” ethylene polymerization catalyst, with the resulting polyethylenes having time-dependent bimodal-like molecular-weight distributions and featuring saturated (n-propyl- and i-butyl-terminated) chain ends. To readily distinguish between bimodal and bimodal-like molecular-weight distributions, we have proposed the use of the dN f/(d log M) – log M representation further to the mainstream dW f/(d log M) – log M one. The consensus mechanism of chain transfer and chain-end formation in the presence of MMAO has been proposed, which explains the composition and amount of terminal alkyl groups in the polymer, and the apparent “multisite-like” nature of the iron catalyst. A comparison between the catalytic behaviors of the “multisite-like” 1/MMAO catalyst system and the truly multisite catalyst system based on Brookhart’s symmetrical bis(imino)pyridine iron catalyst 2 is given.
Here, we proposed a new approach to engineering a photoactivatable CRISPR/Cas9 gene-editing system. The novel nanoCRISPR/Cas9 system is based on the use of auxiliary photocleavable ...oligodeoxyribonucleotides (PC-DNAs) complementary to crRNA. PC-DNAs contained up to three UV-sensitive linkers made of 1-(2-nitrophenyl)-1,2-ethanediol inside the oligonucleotide chain. Immobilizing PC-DNAs on the surface of carbon nanoparticles through 3'-terminal pyrene residue provided sufficient blocking of crRNA (and corresponding Cas9 activity) before UV irradiation and allows for crRNA release after UV irradiation at 365 nm, which restores Cas9 activity. We optimized the length of blocking photocleavable oligonucleotide, number of linkers, time of irradiation, and the type of carbon nanoparticles. Based on the results, we consider the nanoCRISPR/Cas9 system involving carbon-encapsulated iron nanoparticles the most promising. It provides the greatest difference of functional activity before/after irradiation and can be used in prospective for magnetic field-controlled delivery of CRISPR system into the target cells or tissues and spatiotemporal gene editing induced by UV irradiation.
Gender, politics, and society in Ukraine Hankivsky, Olena; Salnykova, Anastasiya
Gender, politics, and society in Ukraine,
c2012, 20121231, 2017, 2012, 2012-12-31, 2013-04-02, 20120101
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Gender, Politics, and Society in Ukraine is particularly innovative in its exploration of both women's and men's experiences and the ways in which gender relations shift over time in societies ...undergoing transitions to democracy.
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