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(D) Protein expression of Runx2, ALP and Osterix in H-PDLSCs, P-PDLSCs and P-PDLSCs with 10-7 Mol/L Osthole as assayed by Western blot. (E) qRT-PCR showed gene expression of fifteen histone acetylases in P-PDLSCs and P-PDLSCs with 10-7 Mol/L Osthole measured by qRT-PCR. (C) Gene expression of Runx2, ALP and Osterix in H-PDLSCs, P-PDLSCs and P-PDLSCs with 10-7 Mol/L Osthole as assayed by qRT-PCR. [Extracted from the article]

It is generally recognized that the stick-slip motion of a polycrystalline diamond compact (PDC) bit is responsible for the low rate of penetration (ROP) and premature failure of the PDC bit when drilling in hard rock formations. To solve this problem, a torsional vibration damping tool was developed. A working principle model of the tool and a calculation model of the optimal spiral angle of the tool was established. The stability of the tool was analyzed, and the parameter range of spiral guideline thread stability was determined. The analysis revealed that the tool can automatically adjust the weight on the bit (WOB) and the rotary speed of the PDC bit through the spiral guide and the disc spring, which could suppress the torsional vibration of the PDC bit and convert part of the vibration load into cutting torque for rock breaking and thus to improve the rate of penetration (ROP). The optimal spiral angle of the tool is proportional to the axial stiffiless, bit diameter, and rock hardness of the drill string system and inversely proportional to the torsional stiffness of the drill string system and the reclining angle of the PDC bit. The stability of the tool is related to the spiral angle, length, and friction angle of the spiral guide. The tools were applied in test wells, and the results indicate that the torque fluctuations are significantly decreased and effectively extend the service life of the PDC bit. During the test process, the tool exhibits steady performance, the feasibility of the tool calculation model was verified. It is anticipated that the presented results will make such drilling a more feasible method for well services. [ABSTRACT FROM AUTHOR]

Inflammatory microenvironment causes the change of epigenetic modification in periodontal ligament stem cells derived from periodontitis tissues (P-PDLSCs), which results in defective osteogenic differentiation compared to cells from healthy tissues. It’s urgent to explore therapeutic strategies aimed at epigenetic targets associated with the regenerative ability of PDLSCs. Osthole, a small-molecule compound extracted from Chinese herbs, has been documented to promote osteogenesis and cell sheets formation of healthy PDLSCs. However, whether osthole shows same effect on P-PDLSCs and the mechanism of promotive effect is still unknown. The purpose of this study was to determine whether Osthole could restore defective osteogenic differentiation of P-PDLSCs via epigenetic modification. We demonstrated that 10−7 Mol/L of Osthole was the best concentration for osteogenic differentiation and proliferation of P-PDLSCs. Mechanistically, we also found that Osthole upregulated MOZ and MORF, histone acetylases that specifically catalyze acetylation of Histone3 lisine9 (H3K9) and Histone3 lisine14 (H3K14), which are key regulators in osteogenic differentiation of P-PDLSCs. Furthermore, Osthole treatment improved cell sheet formation and enhanced the bone formation of PDLSC sheets in animal models of periodontitis. Our study suggests that Osthole is a promising drug to cure periodontitis via regulating epigenetic modification in cell sheets engineering. [ABSTRACT FROM AUTHOR]

A simple two-step process was developed to render steel with lower friction and longer durability. The textured steel substrate was first fabricated by immersed in a piranha solution at room temperature for 10 min. Stearic acid film was then deposited to acquire high hydrophobicity. Scanning electron microscopy and water contact-angle measurements were used to analyze the morphological features and hydrophobicity of prepared samples, respectively. Moreover, the friction-reducing behavior of the organic-inorganic composite film sliding against a steel ball was evaluated in a ball-on-plate configuration. It was found that the stearic acid film on the textured steel led to decreased friction with significantly extended life. [ABSTRACT FROM AUTHOR]

The bioluminescence system of luminescent beetles has extensive applications in biological imaging, protein labeling and drug screening. To explore wild luciferases with excellent catalytic activity and thermal stability, we cloned the luciferase of Pygoluciola qingyu, one species living in areas of high temperature and with strong bioluminescence, by combining transcriptomic sequencing and reverse transcription polymerase chain reaction (RT-PCR). The total length of luciferase gene is 1638 bp and the luciferase consists 544 amino acids. The recombinant P. qingyu luciferase was produced in vitro and its characteristics were compared with those of eight luciferases from China firefly species and two commercial luciferases. Compared with these luciferases, the P. qingyu luciferase shows the highest luminescence activity at room temperature (about 25–28 ℃) with similar KM value for d-luciferin and ATP to the Photinus pyralis luciferase. The P. qingyu luciferase activity was highest at 35 ℃ and can keep high activity at 30–40 ℃, which suggests the potential of P. qingyu luciferase for in vivo and cell application. Our results provide new insights into P. qingyu luciferase and give a new resource for the application of luciferases. [ABSTRACT FROM AUTHOR]

Strong atmospheric absorption attenuation limits the propagation distance of terahertz waves but could also be an advantage in secure communication. In this paper, the transmission characteristics of terahertz waves in clear atmosphere, sand dust, cumulus, and cirrus environment are studied, and the absorption loss and total path loss are calculated. The high path loss exhibited on the atmosphere-limited line-of-sight link indicates that communication security can be improved by limiting the propagation distance. Then, the terahertz transmission channel model of unmanned aerial vehicle (UAV) swarm is given. Combined with the signal transmit power, antenna gain, signal-to-noise ratio (SNR), noise power, and the corresponding path loss threshold, the usable bandwidth of UAV swarm for terahertz secure communication at different flight heights (2–10 km) and propagation distances under complex meteorological conditions is analyzed. The results show that, compared with the clear atmosphere, the communication quality of a UAV swarm decreases most significantly in a cumulus environment, with the usable bandwidth reduced by almost half, while the influence of sand dust and cirrus on the bandwidth is less. With the increase of flight height, the usable bandwidth first increases and then decreases, and the maximum usable bandwidths under different propagation distances all exceed 1 THz. [ABSTRACT FROM AUTHOR]

Clay structures are widely used as impermeable barriers to landfill pollution, although waste can degrade for more than 30 years, no studies concerning the long-term service performance of clay layers under leachate have been reported. In this paper, the in situ clay leaching in landfill for more than 20 years was studied by drilling and sampling. The results show that clay particle contents in soils decreased under long-term leachate effects, causing the liquid limit and plasticity index of the soil to reduce substantially, and the plastic limit to decrease to a lesser extent. The internal friction angle of clay increased, its cohesion decreased, and its compressibility increased, which caused the hydraulic conductivity of clay to increase by 2–4 times at constant porosity following leachate interaction. The long-term effects of leachate led to a reduction in the number of clay minerals, such as montmorillonite, in the soil, the coalescence of soil particles, an increase in the volume of large pores by 132%, a decrease in the volume of small pores by 14.4%, and increased pore connectivity. When landfill waste is undergoing middle and later stages of degradation, the leachate pollutant diffusion depth in the bottom clay layer is approximately 1 m. Since the groundwater is not polluted, our results confirm that the long-term safety aspect of landfill meets the bottom clay impermeability requirements specified in GB16889-2008 (hydraulic conductivity < 10−7 cm/s, thickness > 2 m). [ABSTRACT FROM AUTHOR]

Fireflies are among the most charismatic insects for their spectacular bioluminescence, but the origin and evolution of bioluminescence remain elusive. Especially, the genic basis of luciferin (d-luciferin) biosynthesis and light patterns is largely unknown. Here, we present the high-quality reference genomes of two fireflies Lamprigera yunnana (1053 Mb) and Abscondita terminalis (501 Mb) with great differences in both morphology and luminous behavior. We sequenced the transcriptomes and proteomes of luminous organs of two species. We created the CRISPR/Cas9-induced mutants of Abdominal B gene without luminous organs in the larvae of A. terminalis and sequenced the transcriptomes of mutants and wild-types. Combining gene expression analyses with comparative genomics, we propose a more complete luciferin synthesis pathway, and confirm the convergent evolution of bioluminescence in insects. Using experiments, the function of the firefly acyl-CoA thioesterase (ACOT1) to convert l-luciferin to d-luciferin was validated for the first time. Comparisons of three-dimension reconstruction of luminous organs and their differentially expressed genes among two species suggest that two positive genes in the calcium signaling pathway and structural difference of luminous organs may play an important role in the evolution of flash pattern. Altogether, our results provide important resources for further exploring bioluminescence in insects. [ABSTRACT FROM AUTHOR]

We propose a linearly frequency-tuning single-frequency Nd:YVO laser. We achieve a single-frequency tuning operation with a tuning range of 6.3 GHz and a maximum power of 0.5 W at 1,064 nm by tilting a thin coated etalon and changing the voltage applied to an RTP crystal in a synchronous way. The laser is linearly tuned with a standard frequency variation of ∼190 MHz. We estimate the average tuning speed to be 0.81 GHz/s. The tuning range obtained is more than three times the longitudinal mode spacing of the laser resonator. [ABSTRACT FROM AUTHOR]

Photodynamics of peripheral antenna complexes, light-harvesting complex (LH2) of Rhodobacter (Rb) Sphaeroides 601, was studied using femtosecond pump-probe technique at different laser wavelengths. The obtained results reveal dramatic dynamical evolutions within B800 and B850 absorption bands of antenna complexes LH2. At excitation wavelength around 835 nm, a sharp photobleaching signal was observed which was assigned to the contribution of the two-exciton state, which was further confirmed by the power dependence measurement. Rate equations with eight-level scheme were used to calculate the population evolution in LH2 and the transient dynamics under femtosecond pulse excitation. The research results prove that not only the transition from ground state to one-exciton state but also that from one-exciton state to two-exciton state contribute to the photodynamics of B850. [ABSTRACT FROM AUTHOR]

Ag nanoparticles embedded in soda-lime silicate glass were fabricated by ion-exchange and subsequently annealing method. Z-scan technique, femtosecond time-resolved optical Kerr effect (OKE) technique and femtosecond pump-probe experiment were used to investigate the effects of laser wavelength and laser pulse duration as well as annealing temperature on the third-order optical nonlinearity and ultrafast dynamics of the composites. It was found that the third-order susceptibility of Ag nanoparticles composite glass measured by 400 nm pulse source is larger than that measured by 800 nm pulse source due to an enhancement effect of local field near surface plasmon resonance of Ag nanoparticles in silicate glass. The third-order optical nonlinearity measured by ns laser source is about two orders of magnitude larger than that measured from fs pulse. The annealing temperature has an important effect on the third-order optical nonlinearity and ultrafast dynamics of the composites. Third-order nonlinear susceptibility up to 10-10 esu and fast relaxation process up to 0.2 ps have been obtained in Ag nanoparticles doped glass. [ABSTRACT FROM AUTHOR]