Search

Ultraviolet (UV) illumination can effectively shorten the statistical lag and jitter in gas breakdown processes. The spark gap discharge can produce abundant spectrum including UV waveband. In this paper, a simple but reliable spark gap operating with N2 at atmospheric pressure is used to test optical radiation characteristics, such as spectrum intensity, rise time, fall time, and duration of optical pulse, which are adjusted by changing the circuit or configuration parameters. Three UV-illuminated switches with different UV spark gap configurations have been tested. The experimental results approve our assumption. With a uniform electric field UV spark gap, the breakdown voltage standard deviation percentage of the switch is 0.74%. [ABSTRACT FROM PUBLISHER]

The extensive use of antibiotics causes drug resistance, which slows the healing process in wound infections and this calls for an urgent response to the development of novel therapeutic approaches. However, it is challenging to develop materials with intrinsic and effective antibacterial properties for enhanced wound healing. Here, a highly efficient, bacteria-responsive and controlled-release silver ion coating was constructed by the assembly of quaternized chitosan (QCS), tannic acid (TA), and silver ions using the layer-by-layer method. The coating platform exhibited a distinct "self-defense" behavior triggered by acidification and good antibacterial activity against both gram-negative and gram-positive bacteria, which was further enhanced by the positively charged groups of QCS and the release of silver ions. Moreover, the coatings exhibited excellent biocompatibility, highlighted by promoting both fibroblast and endothelial cell proliferation, supporting fibroblast migration, suppressing macrophage activation, and modulating inflammatory cytokine release. Notably, animal experimental results further revealed that the coatings terminated bleeding, inhibited bacterial growth and accelerated healing at the wound site. Collectively, the coatings showed outstanding hemostatic performance and antimicrobial activity as well as improved wound healing process, which might be as a promising wound treatment platform. [Display omitted] • The coating has a distinct "self-defense" behavior triggered by acidification. • The positive surface charge and silver ions contribute to antibacterial properties. • The coating possesses excellent biocompatibility and anti-inflammatory properties. • The coating has outstanding hemostatic and accelerated wound healing performance. • It shows good application potential as a promising wound treatment platform. [ABSTRACT FROM AUTHOR]

[Display omitted] • FeNi or FeCo@N-doped graphene layer core–shell heterojunctions/N-doped carbon nanorods/rGO composites were synthesized. • The filler loading and rGo could effectively adjust the permittivity. • The strong absorption was achieved of −52.61 dB and −59.42 dB. • The effective absorption bandwidths were up to 4.64 GHz and 5.28 GHz. Rational construction of heterogeneous interfaces is an effective strategy to explore high-performance electromagnetic waves (EMWs) absorption materials. Herein, we adopt a facile solvothermal and pyrolysis process to fabricate the multicomponent and multidimensional composites containing the bimetallic FeNi or FeCo@N-doped graphene layer core–shell heterojunctions/N-doped carbon nanorods/reduced graphene oxide (FeNi@NC/NCR/rGO or FeCo@NC/NCR/rGO) derived from NH 2 -bimetallic (FeNi or FeCo)-metal organic frameworks (MOFs)/GO precursors. The excellent EMWs absorption performances are effectively achieved and regulated via the content of rGO and the filler loading. Compared with the case without rGO, the FeNi@NC/NCR/rGO composite (25 wt% filler loading) displays a strong reflection loss (RL) of −52.61 dB at 14.44 GHz with a thin thickness of 1.65 mm, and effective absorption bandwidth (EAB) is 4.64 GHz. And the FeCo@NC/NCR/rGO composite (20 wt% filler loading) displays a strong RL of −59.42 dB at 17.8 GHz with a thinner thickness of 1.42 mm, and EAB is 5.28 GHz at 1.66 mm. Their excellent absorption properties result from the synergistic effect between the increased dielectric loss (interfacial polarization, dipole polarization and conduction loss), impedance matching and attenuation constant. These results provide a pathway to prepare the multicomponent and multidimensional composites with superior EMWs absorption. [ABSTRACT FROM AUTHOR]

DNA methylation is a crucial element in the epigenetic regulation of mammalian embryonic development. However, its dynamic patterns have not been analysed at the genome scale in human pre-implantation embryos due to technical difficulties and the scarcity of required materials. Here we systematically profile the methylome of human early embryos from the zygotic stage through to post-implantation by reduced representation bisulphite sequencing and whole-genome bisulphite sequencing. We show that the major wave of genome-wide demethylation is complete at the 2-cell stage, contrary to previous observations in mice. Moreover, the demethylation of the paternal genome is much faster than that of the maternal genome, and by the end of the zygotic stage the genome-wide methylation level in male pronuclei is already lower than that in female pronuclei. The inverse correlation between promoter methylation and gene expression gradually strengthens during early embryonic development, reaching its peak at the post-implantation stage. Furthermore, we show that active genes, with the trimethylation of histone H3 at lysine 4 (H3K4me3) mark at the promoter regions in pluripotent human embryonic stem cells, are essentially devoid of DNA methylation in both mature gametes and throughout pre-implantation development. Finally, we also show that long interspersed nuclear elements or short interspersed nuclear elements that are evolutionarily young are demethylated to a milder extent compared to older elements in the same family and have higher abundance of transcripts, indicating that early embryos tend to retain higher residual methylation at the evolutionarily younger and more active transposable elements. Our work provides insights into the critical features of the methylome of human early embryos, as well as its functional relation to the regulation of gene expression and the repression of transposable elements. [ABSTRACT FROM AUTHOR]

Background: Autophagy is a self-degradative process that is important for balancing sources of energy at critical times in development and in response to nutrient stress. Retinal pigment epithelium (RPE) works as the outer blood retina barrier and is vulnerable to energy stress-induced injury. However, the effect of high glucose treatment on autophagy is still unclear in RPE. Methods: Transmission electron microscopy was used to detect the generation of autophagosome. Small interfering RNA (siRNA) and MTT was used to determine the effect of autophagy on cell viability. Western blots and immunohistochemistry were used to detect the expression pattern of autophagic markers, including LC3 and p62. Results: High glucose treatment results in a significant increase in the generation of autophagosome and altered expression of LC3 and p62. High glucose-induced autophagy is independent of mTOR signaling, but is mainly regulated via ROS-mediated ER stress signaling. Conclusion: In the scenario of high glucose-induced oxidative stress, autophagy may be required for the removal of damaged proteins, and provide a default mechanism to prevent high glucose-induced injury in RPE. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Regulation of DNMT1 is critical for epigenetic control of many genes and for genome stability. Using phylogenetic analysis we characterized a block of 27 nucleotides in the 3′UTR of Dnmt1 mRNA identical between humans and Xenopus and investigated the role of the individual elements contained within it. This region contains a cytoplasmic polyadenylation element (CPE) and a Musashi binding element (MBE), with CPE binding protein 1 (CPEB1) known to bind to the former in mouse oocytes. The presence of these elements usually indicates translational control by elongation and shortening of the poly(A) tail in the cytoplasm of the oocyte and in some somatic cell types. We demonstrate for the first time cytoplasmic polyadenylation of Dnmt1 during periods of oocyte growth in mouse and during oocyte activation in Xenopus. Furthermore we show by RNA immunoprecipitation that Musashi1 (MSI1) binds to the MBE and that this element is required for polyadenylation in oocytes. As well as a role in oocytes, site-directed mutagenesis and reporter assays confirm that mutation of either the MBE or CPE reduce DNMT1 translation in somatic cells, but likely act in the same pathway: deletion of the whole conserved region has more severe effects on translation in both ES and differentiated cells. In adult cells lacking MSI1 there is a greater dependency on the CPE, with depletion of CPEB1 or CPEB4 by RNAi resulting in substantially reduced levels of endogenous DNMT1 protein and concurrent upregulation of the well characterised CPEB target mRNA cyclin B1. Our findings demonstrate that CPE- and MBE-mediated translation regulate DNMT1 expression, representing a novel mechanism of post-transcriptional control for this gene. [ABSTRACT FROM AUTHOR]

[Display omitted] • A 3D superstructure is composed of 2D MXene and 1D N-CNT derived from Ni-MOF. • The optimal RL of nanocomposite reached −57.78 dB with thickness of 1.49 mm. • Nanocomposites exhibit excellent and adjustable absorption in C and X band. • Performance enhancement is due to synergistic effect under 3D superstructure. Developing an expandable microstructure method to acquire high-performance microwave absorbers is an effective strategy to prevent electromagnetic wave radiation pollution. In this study, a three-dimensional (3D) conductive network is constructed using 1D carbon nanotubes (CNTs) derived from Ni (hollow and solid microsphere structure) metal–organic-frameworks (MOFs) and 2D Ti 3 C 2 T x MXene simultaneously to form a superstructure composite material. The results of the experiment and analysis confirm the successful synthesis of 3D superstructure composites with excellent microwave absorption (MA) properties. The optimal reflection loss (RL) is − 57.78 dB with a thickness of 1.49 mm at 8.4 GHz, and the maximum effective absorption bandwidth is 3.44 GHz for a thickness of 0.8 mm. In the unique 3D superstructure, microwave attenuation capacity and impedance matching are optimized under the synergistic effect of multiple resonances and polarization relaxation. Simultaneously, adjustable and efficient MA between the C and X bands is achieved by modulating the loading of the Ni particle hybrid. It is anticipated that this superstructure composite material can be used for a new generation of microwave absorbers. [ABSTRACT FROM AUTHOR]

• A novel approach to prepare supramolecular high adhesion 3,5-BTP-PDMS-4 elastomer. • The 3,5-BTP-PDMS-4 obtained high adhesion force, high Young's modulus and energy-containing property. • The 3,5-BTP-PDMS-4 could complete autonomous self-healing at a low temperature of 0 °C. • The 3,5-BTP-PDMS-4 suitable for military applications. Self-healing materials are used in various applications because of their capacity to prolong the material's longevity and durability. Several important properties, including high adhesion force to various surfaces and mechanical robustness have the potential to further expand their application in various fields. In this study, we designed an energy-containing and high-adhesion elastomer (3,5-BTP-PDMS-4), which was fabricated via the click polymerization, that could self-heal at −20 °C. The prepared polymer adhesive exhibited prominent mechanical strength with a high Young's modulus of up to 17.91 MPa. The material also showed that it could autonomously and completely self-heal and restore its mechanical properties within 6 h at room temperature when the 3,5-BTP-PDMS-4 sample was cut into two separate pieces. Moreover, this material was found to possess a high adhesion force of up to 1.65 MPa on steel, which increased when the temperature was reduced. Furthermore, we prepared TATB-based PBXs using 3,5-BTP-PDMS-4 as a binder because of its energy-containing property and excellent self-healing properties to heal cracks generated during fabrication, transportation and storage. Surprisingly, the TATB-based PBXs achieved complete self-healing at 0 °C and partial self-healing at −20 °C, although the low plastic explosive crystals were detrimental to the material's self-healing properties. The successful development of a polymer adhesive that has a high-Young's modulus and can autonomously and completely self-heal could help expand its applications with enhanced versatility in several fields, including military and civil applications. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) radiation and reactive oxygen species (ROS) impair the physiological functions of retinal pigment epithelium (RPE) cells by inducing cell apoptosis, which is the main cause of age-related macular degeneration (AMD). The mechanism by which UV/ROS induces RPE cell death is not fully addressed. Here, we observed the activation of a ceramide-endoplasmic reticulum (ER) stress-AMP activated protein kinase (AMPK) signaling axis in UV and hydrogen peroxide (H2O2)-treated RPE cells. UV and H2O2 induced an early ceramide production, profound ER stress and AMPK activation. Pharmacological inhibitors against ER stress (salubrinal), ceramide production (fumonisin B1) and AMPK activation (compound C) suppressed UV- and H2O2-induced RPE cell apoptosis. Conversely, cell permeable short-chain C6 ceramide and AMPK activator AICAR (5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide) mimicked UV and H2O2's effects and promoted RPE cell apoptosis. Together, these results suggest that UV/H2O2 activates the ceramide-ER stress-AMPK signaling axis to promote RPE cell apoptosis. [ABSTRACT FROM AUTHOR]

In search of an appropriate position for the fluorescent labeling, six chemically available positions of the flavonone core of naringenin have been examined. A number of azido-containing naringenin derivatives were accordingly prepared in various site-specific fashions, and the mild Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition successfully served as the common "Click" labeling tool in the final steps. On the basis of the biological activities of the first batch of labeled compounds, further optimization at the C-6 position of naringenin finally afforded naringenin-flu (27), which acquired 20% of the potency of naringenin and presented good optical properties. Entry of naringenin-flu into living Rhizobium cells was demonstrated by in vitro fluorescent imaging experiments. [ABSTRACT FROM AUTHOR]

Localization method based on skyline for visual geo-location is an important auxiliary localization method that does not use a satellite positioning system. Due to the computational complexity, existing panoramic skyline localization methods determine a small area using prior knowledge or auxiliary sensors. After correcting the camera orientation using inertial navigation sensors, a fine position is achieved via the skyline. In this paper, a new panoramic skyline localization method is proposed that involves the following. By clustering the sampling points in the location area and improving the existing retrieval method, the computing efficiency of the panoramic skyline localization is increased by fourfold. Furthermore, the camera orientation is estimated accurately from the terrain features in the image. Experimental results show that the proposed method achieves higher localization accuracy and requires less computation for a large area without the aid of external sensors. [ABSTRACT FROM AUTHOR]

NodD is the major regulator of nod genes expression in rhizobia. Previously, a HU-like protein in Rhizobium leguminosarum bv. viciae has been identified to bind specifically with nod promoters and be involved in in vitro nodD transcription, but its in vivo function remained unknown. In this work we have cloned and sequenced the R. leguminosarum bv. viciae gene, named hurL, for this HU-like protein. Using the E. coli-expressed HurL proteins, we proved that HurL had high affinity to several nod promoters and showed a stimulation effect on in vitro nodD transcription at appropriate concentration. The R. leguminosarum bv. viciae hurL gene was mutated by insertion of a kanamycin resistance cassette. The obtained hurL mutant strain M704 exhibited poor growth under free-living conditions and failed to induce nodules on Pisum sativum cv. Frisson and Vicia hirsuta. Further studies of NodD production and nod genes- lacZ fusions expression in the hurL mutant revealed that inactivation of hurL led to severe impairment in the nodD expression, repression in the inducible expression of nodA and nodF, and slight enhancement in the expression of px2, a gene identified earlier in this lab. These results suggested that hurL might be required for maintaining the normal expression of nod genes in R. leguminosarum bv. viciae. [ABSTRACT FROM AUTHOR]

CD1d-dependent type I NKT cells, which are activated by lipid antigen, are known to play important roles in innate and adaptive immunity, as are a portion of type II NKT cells. However, the heterogeneity of NKT cells, especially NKT-like cells, remains largely unknown. Here, we report the profiling of NKT (NK1.1+CD3e+) cells in livers from wild type (WT), Jα18-deficient and CD1d-deficient mice by single-cell RNA sequencing. Unbiased transcriptional clustering revealed distinct cell subsets. The transcriptomic profiles identified the well-known CD1d-dependent NKT cells and defined two CD1d-independent NKT cell subsets. In addition, validation of marker genes revealed the differential organ distribution and landscape of NKT cell subsets during liver tumor progression. More importantly, we found that CD1d-independent Sca-1−CD62L+ NKT cells showed a strong ability to secrete IFN-γ after costimulation with IL-2, IL-12 and IL-18 in vitro. Collectively, our findings provide a comprehensive characterization of NKT cell heterogeneity and unveil a previously undefined functional NKT cell subset. [ABSTRACT FROM AUTHOR]

Mouse somatic cells can be chemically reprogrammed into pluripotent stem cells (CiPSCs) through an intermediate extraembryonic endoderm (XEN)-like state. However, it is elusive how the chemicals orchestrate the cell fate alteration. In this study, we analyze molecular dynamics in chemical reprogramming from fibroblasts to a XEN-like state. We find that Sox17 is initially activated by the chemical cocktails, and XEN cell fate specialization is subsequently mediated by Sox17 activated expression of other XEN master genes, such as Sall4 and Gata4. Furthermore, this stepwise process is differentially regulated. The core reprogramming chemicals CHIR99021, 616452 and Forskolin are all necessary for Sox17 activation, while differently required for Gata4 and Sall4 expression. The addition of chemical boosters in different phases further improves the generation efficiency of XEN-like cells. Taken together, our work demonstrates that chemical reprogramming is regulated in 3 distinct "prime–specify–transit" phases initiated with endogenous Sox17 activation, providing a new framework to understand cell fate determination. Yang, Xu, Gu et al. demonstrate that activation of endogenous Sox17 pushes fibroblasts to an extraembryonic endoderm-like state in chemically induced reprogramming of somatic cells into stem cells. This study provides insights into how chemicals prime the transition of somatic cells into stem cells. [ABSTRACT FROM AUTHOR]

The concept of using ibuprofen as an albumin-binding entity was recently demonstrated by the development of [177Lu]Lu-Ibu-PSMA-01. In the present study, we designed a novel ibuprofen-containing radioligand (Ibu-PSMA-02) with subtle structural changes regarding the linker entity in order to investigate a potential impact on the in vitro and in vivo properties. Ibu-PSMA-02 was prepared using solid-phase synthesis techniques and labeled with lutetium-177. [177Lu]Lu-Ibu-PSMA-02 was evaluated in vitro with regard to its plasma protein-binding properties, PSMA affinity and uptake into PSMA-expressing PC-3 PIP tumor cells. The tissue distribution profile of [177Lu]Lu-Ibu-PSMA-02 was assessed in tumor-bearing mice and dose estimations were performed. The in vitro characteristics of [177Lu]Lu-Ibu-PSMA-02 were similar to those previously obtained for [177Lu]Lu-Ibu-PSMA-01 with respect to plasma protein-binding, PSMA affinity and tumor cell uptake. The in vivo studies revealed, however, an unprecedentedly high uptake of [177Lu]Lu-Ibu-PSMA-02 in PC-3 PIP tumors, resulting in an increased absorbed tumor dose of 7.7 Gy/MBq as compared to 5.1 Gy/MBq calculated for [177Lu]Lu-Ibu-PSMA-01. As a consequence of the high tumor accumulation, [177Lu]Lu-Ibu-PSMA-02 showed higher tumor-to-background ratios than [177Lu]Lu-Ibu-PSMA-01. This study exemplified that smallest structural changes in the linker entity of PSMA radioligands may have a significant impact on their pharmacokinetic profiles and, thus, may be applied as a means for ligand design optimization. [ABSTRACT FROM AUTHOR]

In this paper, a 5 Terawatt, 5 MV, 1 MA pulsed power system based on vacuum magnetic insulation is simulated by the particle-in-cell (PIC) simulation method. The system consists of 50 100-kV linear transformer drive (LTD) cavities in series, using magnetically insulated induction voltage adder (MIVA) technology for pulsed power addition and transmission. The pulsed power formation and the vacuum power flow are simulated when the system works in self-limited flow and load-limited flow. When the pulsed power system isn’t connected to the load, the downstream magnetically insulated transmission line (MITL) works in the self-limited flow, the maximum of output current is 1.14 MA and the amplitude of voltage is 4.63 MV. The ratio of the electron current to the total current is 67.5%, when the output current reached the peak value. When the impedance of the load is 3.0 Ω, the downstream MITL works in the self-limited flow, the maximums of output current and the amplitude of voltage are 1.28 MA and 3.96 MV, and the ratio of the electron current to the total current is 11.7% when the output current reached the peak value. In addition, when the switches are triggered in synchronism with the passage of the pulse power flow, it effectively reduces the rise time of the pulse current. [ABSTRACT FROM AUTHOR]

Simultaneous radio and extreme ultraviolet (EUV)/white-light imaging data are examined for a solar type II radio burst occurring on 2010 March 18 to deduce its source location. Using a bow-shock model, we reconstruct the three-dimensional EUV wave front (presumably the type-II-emitting shock) based on the imaging data of the two Solar TErrestrial RElations Observatory spacecraft. It is then combined with the Nançay radio imaging data to infer the three-dimensional position of the type II source. It is found that the type II source coincides with the interface between the coronal mass ejection (CME) EUV wave front and a nearby coronal ray structure, providing evidence that the type II emission is physically related to the CME-ray interaction. This result, consistent with those of previous studies, is based on simultaneous radio and EUV imaging data for the first time. [ABSTRACT FROM AUTHOR]