Energy Transfer Concept in AC/DC Switch Mode Power Supply with Power Factor Correction

A new innovative concept in AC/DC converter that transfers energy to the output side directly from the input line, rather than from the storage capacitor in power factor correction (PFC) cell during the line voltage exceeds the present value. The new concept is based on providing additional winding coupled to the DC/DC transformer connected to the rectified input side to provide a path for the energy transfer from the line to transfer to the output directly (Boost converter) or to be stored in the output transformer Flyback cell)

Mir-23b down-regulates the expression of target gene of acetaldehyde dehydrogenase 1a1 and increases the sensitivity of cervical cancer stem cells to cisplatin

Purpose: To study the effect of miR-23b on the expression of the target gene of acetaldehyde dehydrogenase 1A1 (ALDH1A1), and cisplatin (CDDP) susceptibility of cervical carcinoma stem cells. Methods: Human cervical cancer cell line Hela cells were cultured in vitro, and miR-23b mimic and negative control were transfected into the cells using lipofectamine method. The growth of the two groups of cells was determined using growth curve method, and their proliferation measured using plate clone formation. The influence of treatments on the sensitivity of the cells to CDDP was assayed using MTT method. The mRNA expression of ALDH1A1 in Hela cells was assayed using real-time quantitative polymerase hain reation (PCR), while its protein expression was assayed by Western blot. Results: The levels of expressions of ALDH1A1 protein and mRNA in the miR-23b overexpression group were significantly lower than those in the control group (p < 0.05). The sensitivities of Hela cells to CDDP in the ALDH1A1 inhibition group and the control group were dose-dependent to some extent, but cell inhibition in ALDH1A1 inhibition group markedly increased, relative to control when the CDDP dose was 0.1 ppc (p < 0.01). Conclusion: Up-regulating the expression of miR-23b significantly inhibits the growth and proliferation of cervical cancer cells, and increases their sensitivity to CDDP via down-regulation of the expression of the target gene for ALDH1A1. Therefore, during cervical carcinoma treatment, increasing the level of miR-23b may produce a chemotherapeutic effect. Keywords: MiR-23b, Acetaldehyde dehydrogenase 1A1, Cervical cancer, Cisplatin, Sensitivit

Quantum K Whitney relations for partial flag varieties

In a recent paper, we stated conjectural presentations for the equivariant quantum K ring of partial flag varieties, motivated by physics considerations. In this companion paper, we analyze these presentations mathematically. We prove that if the conjectured relations hold, then they must form a complete set of relations. Our main result is a proof of the conjectured presentation in the case of the incidence varieties. We also show that if a quantum K divisor axiom holds (as conjectured by Buch and Mihalcea), then the conjectured presentation also holds for the complete flag variety.Comment: 25 pages; revised Remark 5.9 and added Example 5.1

Reconstruction of xylose utilization pathway and regulons in Firmicutes

<p>Abstract</p> <p>Background</p> <p>Many Firmicutes bacteria, including solvent-producing clostridia such as <it>Clostridium acetobutylicum</it>, are able to utilize xylose, an abundant carbon source in nature. Nevertheless, homology searches failed to recognize all the genes for the complete xylose and xyloside utilization pathway in most of them. Moreover, the regulatory mechanisms of xylose catabolism in many Firmicutes except <it>Bacillus </it>spp. still remained unclear.</p> <p>Results</p> <p>A comparative genomic approach was used to reconstruct the xylose and xyloside utilization pathway and analyze its regulatory mechanisms in 24 genomes of the Firmicutes. A novel xylose isomerase that is not homologous to previously characterized xylose isomerase, was identified in <it>C. acetobutylicum </it>and several other Clostridia species. The candidate genes for the xylulokinase, xylose transporters, and the transcriptional regulator of xylose metabolism (XylR), were unambiguously assigned in all of the analyzed species based on the analysis of conserved chromosomal gene clustering and regulons. The predicted functions of these genes in <it>C. acetobutylicum </it>were experimentally confirmed through a combination of genetic and biochemical techniques. XylR regulons were reconstructed by identification and comparative analysis of XylR-binding sites upstream of xylose and xyloside utilization genes. A novel XylR-binding DNA motif, which is exceptionally distinct from the DNA motif known for <it>Bacillus </it>XylR, was identified in three Clostridiales species and experimentally validated in <it>C. acetobutylicum </it>by an electrophoretic mobility shift assay.</p> <p>Conclusions</p> <p>This study provided comprehensive insights to the xylose catabolism and its regulation in diverse Firmicutes bacteria especially Clostridia species, and paved ways for improving xylose utilization capability in <it>C. acetobutylicum </it>by genetic engineering in the future.</p

Deletion of Vβ3

In both humans and NOD mice, type 1 diabetes (T1D) develops from the autoimmune destruction of pancreatic beta cells by T cells. Interactions between both helper CD

Generation of a fully erythromycin-sensitive strain of Clostridioides difficile using a novel CRISPR-Cas9 genome editing system

© 2019, The Author(s). Understanding the molecular pathogenesis of Clostridioides difficile has relied on the use of ermB-based mutagens in erythromycin-sensitive strains. However, the repeated subcultures required to isolate sensitive variants can lead to the acquisition of ancillary mutations that affect phenotype, including virulence. CRISPR-Cas9 allows the direct selection of mutants, reducing the number of subcultures and thereby minimising the likelihood of acquiring additional mutations. Accordingly, CRISPR-Cas9 was used to sequentially remove from the C. difficile 630 reference strain (NCTC 13307) two ermB genes and pyrE. The genomes of the strains generated (630Δerm* and 630Δerm*ΔpyrE, respectively) contained no ancillary mutations compared to the NCTC 13307 parental strain, making these strains the preferred option where erythromycin-sensitive 630 strains are required. Intriguingly, the cas9 gene of the plasmid used contained a proximal frameshift mutation. Despite this, the frequency of mutant isolation was high (96% and 89% for ermB and pyrE, respectively) indicating that a functional Cas9 is still being produced. Re-initiation of translation from an internal AUG start codon would produce a foreshortened protein lacking a RuvCI nucleolytic domain, effectively a ‘nickase’. The mutation allowed cas9 to be cloned downstream of the strong Pthl promoter. It may find application elsewhere where the use of strong, constitutive promoters is preferred

Development of an inducible transposon system for efficient random mutagenesis in Clostridium acetobutylicum

Clostridium acetobutylicum is an industrially important Gram-positive organism which is capable of producing economically important chemicals in the ABE (Acetone, Butanol and Ethanol) fermentation process. Renewed interests in the ABE process necessitate the availability of additional genetics tools to facilitate the derivation of a greater understanding of the underlying metabolic and regulatory control processes in operation through forward genetic strategies. In this study, a xylose inducible, mariner-based, transposon system was developed and shown to allow high-efficient random mutagenesis in the model strain ATCC 824. Of the thiamphenicol resistant colonies obtained, 91.9% were shown to be due to successful transposition of the catP-based mini-transposon element. Phenotypic screening of 200 transposon clones revealed a sporulation-defective clone with an insertion in spo0A, thereby demonstrating that this inducible transposon system can be used for forward genetic studies in C. acetobutylicum

Nickel sulfide nanocrystals on nitrogen-doped porous carbon nanotubes with high-efficiency electrocatalysis for room-temperature sodium-sulfur batteries

Polysulfide dissolution and slow electrochemical kinetics of conversion reactions lead to low utilization of sulfur cathodes that inhibits further development of room-temperature sodium-sulfur batteries. Here we report a multifunctional sulfur host, NiS2 nanocrystals implanted in nitrogen-doped porous carbon nanotubes, which is rationally designed to achieve high polysulfide immobilization and conversion. Attributable to the synergetic effect of physical confinement and chemical bonding, the high electronic conductivity of the matrix, closed porous structure, and polarized additives of the multifunctional sulfur host effectively immobilize polysulfides. Significantly, the electrocatalytic behaviors of the Lewis base matrix and the NiS2 component are clearly evidenced by operando synchrotron X-ray diffraction and density functional theory with strong adsorption of polysulfides and high conversion of soluble polysulfides into insoluble Na2S2/Na2S. Thus, the as-obtained sulfur cathodes exhibit excellent performance in room-temperature Na/S batteries

A High-Kinetics Sulfur Cathode with a Highly Efficient Mechanism for Superior Room-Temperature Na-S Batteries

2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Applications of room-temperature-sodium sulfur (RT-Na/S) batteries are currently impeded by the insulating nature of sulfur, the slow redox kinetics of sulfur with sodium, and the dissolution and migration of sodium polysulfides. Herein, a novel micrometer-sized hierarchical S cathode supported by FeS2 electrocatalyst, which is grown in situ in well-confined carbon nanocage assemblies, is presented. The hierarchical carbon matrix can provide multiple physical entrapment to polysulfides, and the FeS2 nanograins exhibit a low Na-ion diffusion barrier, strong binding energy, and high affinity for sodium polysulfides. Their combination makes it an ideal sulfur host to immobilize the polysulfides and achieve reversible conversion of polysulfides toward Na2S. Importantly, the hierarchical S cathode is suitable for large-scale production via the inexpensive and green spray-drying method. The porous hierarchical S cathode offers a high sulfur content of 65.5 wt%, and can deliver high reversible capacity (524 mAh g−1 over 300 cycles at 0.1 A g−1) and outstanding rate capability (395 mAh g−1 at 1 A g−1 for 850 cycles), holding great promise for both scientific research and real application

Magnetic properties of a new molecular-based spin-ladder system: (5IAP)2CuBr4*2H2O

We have synthesized and characterized a new spin-1/2 Heisenberg antiferromagnetic ladder: bis 5-iodo-2-aminopyridinium tetrabromocuprate(II) dihydrate. X-ray diffraction studies show the structure of the compound to consist of well isolated stacked ladders and the interaction between the Cu(2+) atoms to be due to direct Br...Br contacts. Magnetic susceptibility and magnetization studies show the compound to be in the strong-coupling limit, with the interaction along the rungs (J' ~ 13 K) much greater than the interaction along the rails (J ~ 1 K). Magnetic critical fields are observed near 8.3 T and 10.4 T, respectively, establishing the existence of the energy gap.Comment: 10 pages, 4 figures, submitted to Phys. Rev. B Figure 4 did not print. *.eps files replaced with figures.ps fil