Disrupting the Cdk9/Cyclin T1 heterodimer of 7SK snRNP for the Brd4 and AFF1/4 guided reconstitution of active P-TEFb.

P-TEFb modulates RNA polymerase II elongation through alternative interaction with negative and positive regulation factors. While inactive P-TEFbs are mainly sequestered in the 7SK snRNP complex in a chromatin-free state, most of its active forms are in complex with its recruitment factors, Brd4 and SEC, in a chromatin-associated state. Thus, switching from inactive 7SK snRNP to active P-TEFb (Brd4/P-TEFb or SEC/P-TEFb) is essential for global gene expression. Although it has been shown that cellular signaling stimulates the disruption of 7SK snRNP, releasing dephosphorylated and catalytically inactive P-TEFb, little is known about how the inactive released P-TEFb is reactivated. Here, we show that the Cdk9/CycT1 heterodimer released from 7SK snRNP is completely dissociated into monomers in response to stress. Brd4 or SEC then recruits monomerized Cdk9 and CycT1 to reassemble the core P-TEFb. Meanwhile, the binding of monomeric dephosphorylated Cdk9 to either Brd4 or SEC induces the autophosphorylation of T186 of Cdk9. Finally, the same mechanism is employed during nocodazole released entry into early G1 phase of cell cycle. Therefore, our studies demonstrate a novel mechanism by which Cdk9 and CycT1 monomers are reassembled on chromatin to form active P-TEFb by its interaction with Brd4 or SEC to regulate transcription.

[Design and performance study of bone trabecular scaffolds based on triply periodic minimal surface method].

Triply periodic minimal surface (TPMS) is widely used because it can be used to control the shape of porous scaffolds precisely by formula. In this paper, an I-wrapped package (I-WP) type porous scaffolds were constructed. The finite element method was used to study the relationship between the wall thickness and period, the morphology and mechanical properties of the scaffolds, as well as to study the compression and fluid properties. It was found that the porosity of I-WP type scaffolds with different wall thicknesses (0.1 ~ 0.2 mm) and periods (I-WP 1 ~ I-WP 5) ranged from 68.01% ~ 96.48%, and the equivalent elastic modulus ranged from 0.655 ~ 18.602 GPa; the stress distribution of the scaffolds tended to be uniform with the increase of periods and wall thicknesses; the equivalent elastic modulus of the I-WP type scaffolds was basically unchanged after the topology optimization, and the permeability was improved by 52.3%. In conclusion, for the I-WP type scaffolds, the period parameter can be adjusted first, then the wall thickness parameter can be controlled. Topology optimization can be combined to meet the design requirements. The I-WP scaffolds constructed in this paper have good mechanical properties and meet the requirements of repairing human bone tissue, which may provide a new choice for the design of artificial bone trabecular scaffolds.

[Experimental study of the response of articular cartilage surface roughness to load].

Cartilage surface fibrosis is an early sign of osteoarthritis and cartilage surface damage is closely related to load. The purpose of this study was to study the relationship between cartilage surface roughness and load. By applying impact, compression and fatigue loads on fresh porcine articular cartilage, the rough value of cartilage surface was measured at an interval of 10 min each time and the change rule of roughness before and after loading was obtained. It was found that the load increased the roughness of cartilage surface and the increased value was related to the load size. The time of roughness returning to the initial condition was related to the load type and the load size. The impact load had the greatest influence on the roughness of cartilage surface, followed by the severe fatigue load, compression load and mild fatigue load. This article provides reference data for revealing the pathogenesis of early osteoarthritis and preventing and treating articular cartilage diseases.

LncRNA NKILA regulates endothelium inflammation by controlling a NF-κB/KLF4 positive feedback loop.

Endothelium inflammation, a key event in vascular pathological process, can lead to endothelial activation and subsequent vascular disorders. Long non-coding RNA NKILA plays an important regulatory role in pro-inflammatory response. However, the underlying molecular basis by which NKILA regulates endothelial inflammation is poorly understood. In this study, we identify NKILA as a critical repressor to protect the endothelium from inflammation. Mechanistically, we show that NKILA is able to positively mediate the expression of KLF4, an anti-inflammatory atheroprotective regulator in endothelial cells (ECs), by a NF-κB-mediated DNA methylation mechanism. Moreover, NF-κB is found to help recruit DNMT3A to the CpG island of KLF4 promoter, facilitating KLF4 promoter DNA methylation and transcriptional repression. More importantly, we find KLF4 can inversely attenuate NF-κB transcriptional activity via establishing a NF-κB/KLF4 positive feedback loop, which is under the control of NKILA. Hence, sustained endothelium inflammation will occur, once the NKILA becomes dysfunctional. These studies revealed that NKILA can function as a vital regulator to protect the endothelium from inflammatory lesions and related vascular diseases.

Removal of multiple heavy metal ions using a macromolecule chelating flocculant xanthated chitosan.

In this paper, the removal performance and mechanism of xanthated chitosan (XCTS) towards heavy metal ions are investigated. XCTS possesses both strong chelating abilities and excellent flocculation properties, which can effectively remove several kinds of heavy metal ions, such as Cr3+, Cu2+, Mn2+, Ni2+, Pb2+ and Zn2+. It has a good potential for practical application. In a flocculation test of a mixed component solution, the removal rates of Cr3+, Cu2+ and Cd2+ reach 100%, 100% and 99.1%, respectively. The removal rates are significantly greater than that of a single component solution. It indicates that there is a synergistic effect between different metal ions. Moreover, the selectivity of XCTS for Cr3+ and Cu2+ is obviously superior to that for Cd2+; XCTS is easier to combine with the heavy metal ions belonging to hard acids.

Design and Realization of Rural Environment Art Construction of Cultural Image and Visual Communication.

The practice of rural construction has been exploring and trying to adapt to the needs of rural development in various periods. In recent years, under the attention and promotion of the central policy, various social forces have joined the ranks of rural construction, and art intervention in rural construction has begun as a new method. Entering the public eye, it deeply intervenes in the construction and development of the countryside in a more gentle way, from the key point of interaction between the social and cultural orientation and the material needs of the countryside. However, most of the art interventions in rural construction practice only unilaterally use artistic techniques to beautify local areas or display works, without realizing the hidden artistic and cultural value of the village and ignoring the participation and role of the villagers in the whole process. After the construction is completed, once the foreign construction forces are withdrawn, the development of the village will stagnate. Therefore, mobilizing the main body of rural construction (original villagers) to participate in the joint construction of the village is an important link to solve the current problems of art intervening in the construction of rural settlements.

Direct calibration of neutron detectors for laser-driven nuclear reaction experiments with a gated neutron source.

Nowadays, the sustained technological progress in high-intensity lasers is opening up the possibility of super-intense laser pulses to trigger or substantially influence nuclear reactions. However, it is a big challenge to quantitatively measure the reaction products because of the interference of electromagnetic pulses induced by high-intensity lasers. Fast scintillation detectors are widely chosen for fast neutron detection. The calibration of neutron detectors is crucial to measuring the yield of neutron products. Since one large signal superimposed by a number of neutron signals appears during a short period, it is difficult to directly and precisely calibrate the detectors' response for a single neutron. In the present work, we developed a direct calibration method with a gated fission neutron source 252Cf to solve this problem. This work demonstrates that the gated fission neutron source approach, with a unique "Pulse Shape Discrimination & Time of Flight window" function, has the highest background-γ-rejection and improves the confidence level of the final results for both liquid and plastic scintillator. Compared with the result of Compton edge method and neutron beam method, the gated fission neutron source method achieves much cleaner neutron signals and avoids interference caused by the modeling accuracy of the neutron detectors. This approach can be widely used in laser-driven nuclear physics experiments with higher accuracy for neutron detection.

A novel method for selecting the set optimal wavelength combination in multi-spectral transmission image.

In the process of detecting heterogeneity in breast tissue based on multi-spectral transmission imaging, the detection accuracy will be affected due to the high redundancy degree of information between bands. In order to select the reasonable wavelength combination, this paper uses various nonlinear transformations to convert the multi-spectral images into spectral data for the first time, so as to select the set optimal wavelength combination based on the successive projections algorithm (SPA). Firstly, we design the collection experiment of 4-wavelength multi-spectral image. And then, K-SVD dictionary learning method, texture extraction method and gray correlation analysis method are used to obtain the feature spectral information. Finally, the set optimal wavelength combination is selected based on SPA. The experimental results show that random forest (RF) classification model and Faster-RCNN recognition models effectively verify that the combination of wavelengths 1,2,4 selected has the highest accuracy in the heterogeneous detection. In conclusion, this paper uses modulation-frame accumulation technique to improve the quality of multi-spectral transmission images. And based on the RF and Faster-RCNN models, the effectiveness of SPA-based optimal wavelength combination method proposed is verified, which will provide a new idea of feature wavelength selection for screening early breast masses through multi-spectral transmission imaging.

Recognition of Heterogeneous Edges in Multiwavelength Transmission Images Based on the Weighted Constraint Decision Method.

Multiwavelength light transmission imaging provides a possibility for early detection of breast cancer. However, due to strong scattering during the transmission process of breast tissue analysis, the transmitted image signal is weak and the image is blurred and this makes heterogeneous edge detection difficult. This paper proposes a method based on the weighted constraint decision (WCD) method to eliminate the erosion and checkerboard effects in image histogram equalization (HE) enhancement and to improve the recognition of heterogeneous edge. Multiwavelength transmission images of phantom are acquired on the designed experimental system and the mask image with high signal-to-noise ratio (SNR) is obtained by frame accumulation and an Otsu thresholding model. Then, during image enhancement the image is divided into low-gray-level (LGL) and high-gray-level (HGL) regions according to the distribution of light intensity in image. And the probability density distribution of gray level in the LGL and HGL regions are redefined respectively according to the WCD method. Finally, the reconstructed image is obtained based on the modified HE. The experimental results show that compared with traditional image enhancement methods, the WCD method proposed in this paper can greatly improve the contrast between heterogeneous region and normal region. Moreover, the correlation between the original image data is maintained to the greatest extent, so that the edge of the heterogeneity can be detected more accurately. In conclusion, the WCD method not only accurately identifies the edge of heterogeneity in multiwavelength transmission images, but it also could improve the clinical application of multiwavelength transmission images in the early detection of breast cancer.

Measurement of quantitative viscoelasticity of bovine corneas based on lamb wave dispersion properties.

The viscoelastic properties of the human cornea can provide valuable information for clinical applications such as the early detection of corneal diseases, better management of corneal surgery and treatment and more accurate measurement of intra-ocular pressure. However, few techniques are capable of quantitatively and non-destructively assessing corneal biomechanics in vivo. The cornea can be regarded as a thin plate in which the vibration induced by an external vibrator propagates as a Lamb wave, the properties of which depend on the thickness and biomechanics of the tissue. In this study, pulses of ultrasound radiation force with a repetition frequency of 100 or 200 Hz were applied to the apex of corneas, and the linear-array transducer of a SonixRP system was used to track the tissue motion in the radial direction. Shear elasticity and viscosity were estimated from the phase velocities of the A0 Lamb waves. To assess the effectiveness of the method, some of the corneas were subjected to collagen cross-linking treatment, and the changes in mechanical properties were validated with a tensile test. The results indicated that the shear modulus was 137 ± 37 kPa and the shear viscosity was 3.01 ± 2.45 mPa · s for the group of untreated corneas and 1145 ± 267 kPa and was 0.16 ± 0.11 mPa · s for the treated group, respectively, implying a significant increase in elasticity and a significant decrease in viscosity after collagen cross-linking treatment. This result is in agreement with the results of the mechanical tensile test and with reports in the literature. This initial investigation illustrated the ability of this ultrasound-based method, which uses the velocity dispersion of low-frequency A0 Lamb waves, to quantitatively assess both the elasticity and viscosity of corneas. Future studies could discover ways to optimize this system and to determine the feasibility of using this method in clinical situations.