Live cell imaging experiments have shown that, although eukaryotic chromosome is compact, the distal dynamics between enhancers and promoters are unusually rapid and cannot be explained by standard polymer models. The discordance between the compact static chromatin organization and the relaxation times is a conundrum that violates the expected structure-function relationship. To resolve the puzzle, we developed a theory to predict chromatin dynamics by first calculating the precise three-dimensional (3D) structure using static Hi-C contact maps or fixed-cell imaging data. The calculated 3D coordinates are used to accurately forecast the two-point dynamics reported in recent experiments that simultaneously monitor chromatin dynamics and transcription. Strikingly, the theory not only predicts the observed fast enhancer-promoter dynamics but also reveals a novel subdiffusive scaling relationship between two-point relaxation time and genomic separation, in near quantitative agreement with recent experiments but diverging sharply from the expectations based on fractal globule models that are good descriptors of global organization of chromosomes. As a by product, we predict that cohesin depletion speeds up the dynamics between distal loci. Our framework shows that chromatin dynamics can be predicted based solely on static experimental data, reinforcing the concept that the three-dimensional structure determines their dynamic behavior. The generality of the theory opens new avenues for exploring chromatin dynamics, especially transcriptional dynamics, across diverse species.
Dynamic nonlinearities of C70/toluene solution are measured and analysed by an improved picosecond time-resolved pump-probe system based on a nonlinear imaging technique with phase object. The photophysical parameters are determined by the five-level model, which is adopted to interpret the experimental data. The change of refraction index per unit density of the excited state obtained by a numerically simulation is a critical factor to determine the nonlinear behaviour of C70 in picosecond time regime.
Abstract The dynamic response of polar nanoregions under an AC electric field was investigated by measuring the frequency dependence of the quadratic electro-optic (QEO) effect in a paraelectric KTa 0.61 Nb 0.39 O 3 single crystal near the para-ferroelectric phase boundary (0 °C < T - T c < 13 °C). The QEO coefficient R 11 − R 12 reached values as large as 5.96 × 10 −15 m 2 /V 2 at low frequency (500 Hz) and gradually decreased to a nearly stable value as the frequency increased to 300 kHz. Furthermore, a distortion of the QEO effect was observed at low frequency and gradually disappeared as R 11 − R 12 tended towards stability. The giant QEO effect in the KTa 0.61 Nb 0.39 O 3 crystal was attributed to the dynamic rearrangement of polar nanoregions and its anomalous distortion can be explained by considering the asymmetric distribution of polar nanoregions.
In the present work slight benzylation of sisal fibre was carried out to prepare natural resource based self reinforced composites. By controlling the degree of benzylation, the outer layer of the ultimate cells was converted into thermoplastic and the inner part maintained the load bearing ability. When these modified fibres were moulded under certain temperature and pressure, the thermoplasticised portion flowed freely and served as matrix, while the unaffected parts in the core can still provide reinforcing effect. Such an all-plant fibre composite is characterised by self-reinforcement, easy processing and low cost.
Excited-state intramolecular proton transfer (ESIPT) molecules has been using as a variety of functionalityled molecular systems. To investigate the relationship between the electron-donor substitution and luminescent properties of ESIPT luminogens, four 2-(2-hydroxyphenyl) benzothiazole derivatives with donor-π-acceptor (D-π-A)-structured were synthesized. The distinct fluorescence properties of them were found to be highly dependent on the electron-donor moiety (triphenylamine and anthracenyl), its substituent position (para and meta position) and solvent polarity. The M-TPA, P-En, and M-En showed ESIPT emission in organic solvents, while the P-TPA showed intramolecular charge transfer process (ICT) emission. It is due to the synergistic effect of the aggregation-induced emission (AIE) and ESIPT, that M-TPA and M-En exhibited high solid-state quantum yields and large Stokes shifts. They were used as a probe for detecting F-, which resulted in rapid colorimetric, high sensitivity and good selectivity. The M-TPA was a turn-on fluorescent probe, which had the best detection property, and the limit of detection was as low as 11 nM. Because M-TPA displayed phenol anion emission in DMSO and F- causes the deprotonation of the M-TPA, which led to significant red shift of the absorption band and enhancement of fluorescence emission. This work provides a reliable strategy for designing high-performance fluorescent sensor via ESIPT manipulation.
Abstract Aiming at mercury and dioxin in fire coal gas as research objects, nonthermal plasma (NTP) catalytic technology was used to investigate the degradation effect of operating condition parameters on mixed pollutants in mixed flue gas condition, and to explore the synergistic degradation of Hg 0 and TCB (1, 2, 3-trichlorobenzene, TCB) under mixed flue gas conditions. The research results showed that the conversion efficiency of mercury and TCB increased with the additional output of voltage, and decreased with the increase of the gas flow rate. Under optimal reaction conditions: voltage = 17 kV, frequency = 300 Hz, gas flow rate = 2 l min −1 , the conversion efficiency of Hg 0 and TCB reached the highest 91.4% and 84.98%, respectively. In the NTP catalytic system, active free radicals played an important role in the synergistic conversion of mercury and TCB, which have a competitive effect, to make the conversion efficiency of mixed pollutants lower than a single substance. In the mixed flue gas condition, the mixed gas has an inhibitory effect on the synergistic conversion of mercury and TCB. Kinetic modeling of NTP catalytic synergistic reaction was established. Under three conditions of TCB, mercury and TCB, mixed simulated flue gas, the NTP catalytic technology showed a quasi-first-order kinetic reaction for the degradation of TCB. According to the synergistic effect of NTP and composites, the transformation and degradation of TCB mainly included two processes: TCB and ring opening, and Hg 0 was finally oxidized to Hg 2+ .
The introduction of hydrophilic groups, such as -COOH, -SO3, -OH, -O-, into the polyurethane resin, so that waterborne polyurethane products in the water resistance, solvent resistance, weather and other aspects of performance are worse than solvent borne systems. In our work, to improve the water resistance of the films for waterborne polyurethane, we incorporated C=C bond into the side chain of polyurethane by using pentaerythritol diacrylate as an extension agent. By measuring the cured polyurethane films absorption and mechanical properties, we determine the conditions for UV curing, 3% TMPME, photoinitiator (2959) and to UV light application time for 30s. With the increase of the amount PEDA, water resistance, hardness and tensile strength increase. Furthermore, with the improved water resistance, it is hoped that the performance of waterborne polyurethane can be comparative or superior to the solvent-borne systems.
SDSS J125438.25+114105.8 is a newly identified radio-loud narrow-line Seyfert 1 galaxy,a recently discovered new class of active galactic nuclei,which was suggested to have relativistic jets aligned to the line of sight based on recent observations.We searched for optical microvariability in SDSS J125438.25+114105.8 in four nearly successive observing nights,with the LiJiang 2.4-m telescope of Yunnan Observatory.Rapid variations of the optical emission were detected on timescales as short as a few hours,with the maximum amplitude reaching nearly 0.1 mag. This is the second reported case of optical microvariability detected in radio-loud NLS1 galaxies. Our result indicates that its observed optical light is significantly contributed by non-thermal emission, most likely from relativistic jets,suggested by the study of multiwavelength properties as well as the most recentγ-ray observations made with the Fermi satellite.
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