Low temperature solder (In-based, Sn-Bi, Sn-Zn) has great advantages in aerospace and through-hole technology assemblies in IBM mainframe due to its unique low temperature characteristics. The review ...evaluates the effects of alloying elements, rare earth elements and nanoparticles on the wettability, microstructure, mechanical properties and oxidation resistance of the low-temperature solders.
Understanding gene transcription and mRNA-protein (mRNP) dynamics in single cells in a multicellular organism has been challenging. The catalytically dead CRISPR-Cas13 (dCas13) system has been used ...to visualize RNAs in live cells without genetic manipulation. We optimize this system to track developmentally expressed mRNAs in zebrafish embryos and to understand features of endogenous transcription kinetics and mRNP export.
We report that zygotic microinjection of purified CRISPR-dCas13-fluorescent proteins and modified guide RNAs allows single- and dual-color tracking of developmentally expressed mRNAs in zebrafish embryos from zygotic genome activation (ZGA) until early segmentation period without genetic manipulation. Using this approach, we uncover non-synchronized de novo transcription between inter-alleles, synchronized post-mitotic re-activation in pairs of alleles, and transcriptional memory as an extrinsic noise that potentially contributes to synchronized post-mitotic re-activation. We also reveal rapid dCas13-engaged mRNP movement in the nucleus with a corralled and diffusive motion, but a wide varying range of rate-limiting mRNP export, which can be shortened by Alyref and Nxf1 overexpression.
This optimized dCas13-based toolkit enables robust spatial-temporal tracking of endogenous mRNAs and uncovers features of transcription and mRNP motion, providing a powerful toolkit for endogenous RNA visualization in a multicellular developmental organism.
In this article, the design, principle, and characterization of a 3-D metamaterial absorber (MA) have been presented, which consists of the spatial lossy transmission lines (SLTLs) and the ...resistively loaded high impedance surface (HIS). The proposed MA possesses a fractional bandwidth of 193% with absorption rate of above 90% in the frequency range from 2 to 110 GHz under TM polarization while maintaining large oblique incident angle stability of over 50<inline-formula> <tex-math notation="LaTeX">^{\circ}</tex-math> </inline-formula>. For demonstration, a prototype is fabricated, whose measurement results are in good agreement with the simulation results. Losses from the periodically patterned SLTLs and resistively loaded HIS are introduced by resistive graphene films using screen-printing technology, resulting in avoiding conventional soldering of numerous lumped resistors. An equivalent circuit model and a surface loss distribution are given to better illustrate the physical mechanism. Our findings establish general and systematic strategies for guiding the design of extremely wideband MA with large incident angle and pave the way for enhancing the microwave performance in applications of electromagnetic compatibility, imaging, radar detection, and stealth.
, a common food-borne pathogen, forms biofilms and generates virulence factors through a quorum sensing (QS) mechanism. In this study, six compounds (dankasterone A, demethylincisterol A
, ...zinnimidine, cyclo-(L-Val-L-Pro), cyclo-(L-Ile-L-Pro), and cyclo-(L-Leu-L-Pro)) were isolated from the endophytic fungus
of the
sp. in the South China Sea. Among them, demethylincisterol A
, a sterol derivative, exhibited strong QS inhibitory activity against
. The QS inhibitory activity of demethylincisterol A
was evaluated through experiments. The minimum inhibitory concentration (MIC) of demethylincisterol A
against
was 6.25 μg/mL. At sub-MIC concentrations, it significantly decreased biofilm formation, hindered mobility, and diminished the production of protease and hemolysin activity. Moreover, RT-qPCR results demonstrated that demethylincisterol A
markedly inhibited the expression of QS-related genes (
and
) in
. The exposure to demethylincisterol A3 resulted in the downregulation of genes (
,
,
,
,
,
,
, and
) associated with biofilm formation, mobility, and virulence factors. Hence, demethylincisterol A
is a potentially effective compound in the pipeline of innovative antimicrobial therapies.
ETHNOPHARMCOLOGICAL RELEVANCEThe formation of biofilms is a factor leading to chronic infection and drug resistance in melioidosis. The production of biofilm formation and many virulence factors are ...regulated by quorum sensing (QS). Therefore, the discovery of QS inhibitors to reduce antibiotic abuse has attracted a lot of attention. In this case, the methanol extract of a unique ethnic medicinal plant partridge tea (Mallotus oblongifolius (Miq.) Müll.Arg.) and its isolated active compound were used as biofilms and QS inhibitors against Burkholderia thailandensis.AIM OF THE STUDYThe purpose of this study is to investigate the anti-biofilm and anti-QS effect of the ethnic medicinal plant partridge tea and its active compounds against B. thailandensis.METHODSActive compound was isolated using classical phytochemical separation techniques under activity tracking. The biofilm and virulence factors (Proteases, lipases, rhamnolipids, and motility) of B. thailandensis were used to evaluate the activity of crude extracts and isolated compounds.RESULTSIn this study, the extract of partridge tea and MG had good QS inhibitors activity against B. thailandensis E264. MG was investigated to inhibit QS-related virulence factors and the biofilm formation against B. thailandensis E264. The lipase activity of B. thailandensis E264 decreased by 49.41% at 150 μg/mL. At 75 μg/mL and 150 μg/mL, the erasion of mature biofilms reached 28.18% and 70.87%, respectively. Correspondingly, 150 μg/mL MG could significantly decrease btaR1 and btaR3 by 55.78% and 56.24%, respectively. Contradictorily, the rhamnolipid production of B. thailandensis E264 was 1.67 folds that of the control group at 150 μg/mL MG.CONCLUSIONThrough molecular docking analysis and biological phenotype data, we speculate that MG may inhibit the biofilms and virulence factors of B. thailandensis E264 by interfering two QS systems, BtaI1/R1 and BtaI3/R3. Therefore, MG should be one potential QSI for the treatment of Burkholderia pathogens.
CotA-laccases are potential enzymes that are widely used in decolorization of dyes and degradation of toxic substances. In this study, a novel CotA-laccase gene from Bacillus pumilus W3 was applied ...for rational design. After a series of site-directed genetic mutations, the mutant S208G/F227A showed a 5.1-fold higher catalytic efficiency (kcat/Km) than the wild-type CotA-laccase did. The optimal pH of S208G/F227A was 3.5 with ABTS as substrate. The residual activity of mutant S208G/F227A was more than 80% after incubated for 10 h at pH 7–11. Mutant S208G/F227A showed optimal temperature at 80°C with ABTS as substrate. The thermal stability of mutant laccase S208G/F227A was lower than that of wild-type CotA-laccase. This study showed that Gly208 and Ala227 play key roles in catalytic efficiency and it is possible to improve catalytic efficiency of CotA-laccase through site-directed mutagenesis.
Triggering receptor expressed on myeloid cells 2 (TREM2) is a DAP12-associated receptor expressed in microglia, macrophages, and other myeloid-derived cells. Previous studies have suggested that ...TREM2/DAP12 signaling pathway reduces inflammatory responses and promotes phagocytosis of apoptotic neurons. Recently, TREM2 has been identified as a risk gene for Alzheimer disease (AD). Here, we show that DAP12 stabilizes the C-terminal fragment of TREM2 (TREM2-CTF), a substrate for γ-secretase. Co-expression of DAP12 with TREM2 selectively increased the level of TREM2-CTF with little effects on that of full-length TREM2. The interaction between DAP12 and TREM2 is essential for TREM2-CTF stabilization as a mutant form of DAP12 with disrupted interaction with TREM2 failed to exhibit such an effect. Silencing of either Trem2 or Dap12 gene significantly exacerbated pro-inflammatory responses induced by lipopolysaccharides (LPS). Importantly, overexpression of either full-length TREM2 or TREM2-CTF reduced LPS-induced inflammatory responses. Taken together, our results support a role of DAP12 in stabilizing TREM2-CTF, thereby protecting against excessive pro-inflammatory responses.
TREM2 is a DAP12-coupled receptor associated with neurodegenerative diseases.
Co-expression of DAP12 increased the level of TREM2 C-terminal fragment (TREM2-CTF) which suppressed the release of pro-inflammatory cytokines.
A major function of DAP12 is to stabilize TREM2-CTF, which regulates inflammatory responses in microglia.
Our studies unraveled a novel function of DAP12 and provided new link between TREM2/DAP12 complexes and neuroinflammation.
A testing research on the local-biaxial flexural interactive buckling of high strength steel Q460C, Q550D and Q690D welded box slender section beam-columns subjected to combined compression force and ...biaxial bending is reported. A total of thirteen median long steel columns, of which four manufactured from Q460C steel, five from Q550D steel and four from Q690D steel, were loaded until failure under biaxial eccentric compression forces. The local-biaxial flexural interaction buckling behavior is investigated by analyzing the test results. As an addition to the test data, the finite element parameter analyses are performed. The ultimate bearing capacities obtained from the test in this study and the numerical results presented in this study or in the existent literatures are compared with the calculation results in accordance with the design methods recommended in the American Specification ANSI/AISC 360–16, Eurocodes BS EN 1993-1-1 and BS EN 1993-1-5, and the newly proposed Effective Yield Strength Method (EYSM) and Effective Section Method (ESM) to check whether the current technical provisions and the new methods are suitable to the high strength steel beam-columns examined in this paper. The experimental and numerical results show that after taking the resistance factor into account, the ANSI/AISC 360–16, EN 1993-1-1 and BS EN 1993-1-5 are very conservative for the high strength steel beam-columns with greater member slenderness ratios (λ = 80, 90, 100) or with smaller plate width-to-thickness ratios (square box sections with b/t = 40, or rectangular box sections with h/t = 40 or b/t = 17); the new proposed EYSM provides an excellent prediction of the ultimate bearing capacities of the beam-columns and thus suitable for the high strength steels; but the new proposed ESM gives a very conservative estimate, over the range of steel nominal yield stress fy = 460 MPa ∼ 690 MPa, plate width-to-thickness ratio b/t = 40–80, member slenderness ratio λ = 40–100.
•A testing research on the local-biaxial flexural interactive buckling of high strength steel welded box slender section beam-columns subjected to combined compression force and biaxial bending is reported. The local-biaxial flexural interaction buckling behavior is investigated.•The ultimate bearing capacities obtained from the test in this study and the numerical results presented in this paper or in the existent literatures are compared with the calculation results in accordance with the design methods recommended in the American Specification ANSI/AISC 360–16, Eurocodes BS EN 1993-1-1 and BS EN 1993-1-5, and the newly proposed Effective Yield Strength Method (EYSM) and Effective Section Method (ESM) to check whether the current technical provisions and the new methods are suitable to the high strength steel beam-columns examined.•The experimental and numerical results show that after taking the resistance factor into account, the ANSI/AISC 360–16, EN 1993-1-1 and BS EN 1993-1-5 are very conservative for the high strength steel beam-columns with greater member slenderness ratios (λ = 80, 90, 100) or with smaller plate width-to-thickness ratios (square box sections with b/t = 40, or rectangular box sections with h/t = 40 or b/t = 17); the new proposed EYSM provides an excellent prediction of the ultimate bearing capacities of the beam-columns and thus suitable for the high strength steels; but the new proposed ESM gives a very conservative estimate, over the range of steel nominal yield stress fy = 460 MPa ∼ 690 MPa, plate width-to-thickness ratio b/t = 40–80, member slenderness ratio λ = 40–100.
A dual-band bandpass filter (BPF) with independently tunable attenuation based on graphene nanoplates is proposed. By utilizing dual coupling paths, the 1.2- and 2-GHz frequency bands realized by the ...multimode resonant structure can be completely controlled. The graphene nanoplates loaded close to the resonator are responsible for independently tunable attenuation. Meanwhile, the influence of the loaded graphene nanoplates on the original dual-band BPF is analyzed in detail. New branches are added to achieve a stronger coupling of source, load, and passband. Due to good separation of the dual coupling paths and the controllable attenuation of graphene to the signal, a novel dual-band BPF with independently tunable attenuation is obtained. The measured results show that the dual-band BPF achieves independently tunable attenuation of about −4 dB in two passbands with a low reflection of less than −10 dB.
We propose and demonstrate the linearly polarized converters for reflected and transmitted waves based on a double-split ring resonator (DSRR). For reflective polarization converter, the ...three-layered metamaterial structure can rotate the polarization state of incident linearly polarized wave into its orthogonal one. The calculated results indicate that the polarization conversion ratio of reflective polarization rotator can reach unity (99.99%) at the resonant frequency. For transmissive polarization rotator, we propose a multi-layered metamaterial structure at terahertz frequencies which exhibits the incident y-polarized wave can be thoroughly and perfectly converted to the x-polarized output wave over the entire frequency range. The numerical simulation and theoretical calculation indicate that polarization conversion ratio of the y-polarized wave can be higher than 99.98% at the frequency range from 0.42 to 1.59 THz. Additionally, we investigate the polarization rotation properties based on optical activity and ellipticity. Specifically, the proposed structure can achieve simultaneously a multi-band 90
o
polarization rotation angle and an extremely low dispersion (lower than 0.25
o
, absolute value). The physical mechanism of polarization conversion is also analyzed based on the electronic field distribution at the resonance frequency.
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