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1.
Mol Microbiol ; 121(1): 40-52, 2024 01.
Article in English | MEDLINE | ID: mdl-37994189

ABSTRACT

Here, we employ coelution experiments and far-western blotting to identify stable interactions between the main components of the B. subtilis degradosome and the small proteins SR1P and SR7P. Our data indicate that B. subtilis has a degradosome comprising at least RNases Y and PnpA, enolase, phosphofructokinase, glycerol-3-phosphate dehydrogenase GapA, and helicase CshA that can be co-purified without cross-linking. All interactions were corroborated by far-western blotting with proteins purified from E. coli. Previously, we discovered that stress-induced SR7P binds enolase to enhance its interaction with and activity of enolase-bound RNase Y (RnY), while SR1P transcribed under gluconeogenic conditions interacts with GapA to stimulate its interaction with and the activity of RnjA (RnjA). We show that SR1P can directly bind RnjA, RnY, and PnpA independently of GapA, whereas SR7P only interacts with enolase. Northern blotting suggests that the degradation of individual RNAs in B. subtilis under gluconeogenic or stress conditions depends on either RnjA or RnY alone or on RnjA-SR1P, RnY-SR1P, or RnY-Eno. In vitro degradation assays with RnY or RnjA substrates corroborate the in vivo role of SR1P. Currently, it is unknown which substrate property is decisive for the utilization of one of the complexes.


Subject(s)
Bacillus subtilis , Escherichia coli , Multienzyme Complexes , Bacillus subtilis/genetics , Bacillus subtilis/metabolism , Escherichia coli/genetics , Escherichia coli/metabolism , Endoribonucleases/metabolism , RNA Helicases/metabolism , Polyribonucleotide Nucleotidyltransferase/metabolism , Phosphopyruvate Hydratase/genetics , Phosphopyruvate Hydratase/metabolism
2.
Blood Cells Mol Dis ; 110: 102895, 2024 Sep 18.
Article in English | MEDLINE | ID: mdl-39303397

ABSTRACT

Small molecules UM171 and SR1 have already been taken into clinically-oriented protocols for the ex vivo expansion of hematopoietic stem (HSCs) and progenitor (HPCs) cells. In order to gain further insight into their biology, in the present study we have assessed their effects, both individually and in combination, on the in vitro long-term proliferation and expansion of HSCs and HPCs contained within three different cord blood-derived cell populations: MNCs (CD34+ cells = 0.8 %), LIN- cells (CD34+ cells = 41 %), and CD34+ cells (CD34+ cells >98 %). Our results show that when added to cultures in the absence of recombinant stimulatory cytokines, neither molecule had any effect. In contrast, when added in the presence of hematopoietic cytokines, UM171 and SR1 had significant stimulatory effects on cell proliferation and expansion in cultures of LIN- and CD34+ cells. No significant effects were observed in cultures of MNCs. The effects of both molecules were more pronounced in cultures with the highest proportion of CD34+ cells, and the greatest effects were observed when both molecules were added in combination. In the absence of small molecules, cell numbers reached a peak by days 25-30, and then declined; whereas in the presence of UM171 or/and SR1 cell numbers were sustained up to day 45 of culture. Our results indicate that besides CD34+ cells, LIN- cells could also be used as input cells in clinically-oriented expansion protocols, and that using both molecules simultaneously would be a better approach than using only one of them.

3.
Nanotechnology ; 35(27)2024 Apr 19.
Article in English | MEDLINE | ID: mdl-38522106

ABSTRACT

Light and thermal detectors based on the laser-induced transverse voltage (LITV) effect have garnered significant interest for their rapid and broad spectral response. In this study, we prepared the La-doped SrTiO3(STO) epitaxial thin films on the 12° inclined single crystal LaAlO3(LAO) (100) substrates using our home-designed metal-organic chemical vapor deposition system. Under the illumination of a 248 nm laser, the LITV signals of LaxSr1-xTiO3films were observed and showed dependence on the La doping level, which can be explained by the changes in the light absorption coefficient, thermal conductivity, and optical penetration depth. The optimized LITV signal was observed with a peak voltage of 23.25 V and a decay time of 106 ns under the laser power density of 1.0 mJ mm-2. The high peak voltage and fast response time of LaxSr1-xTiO3show great potential in the field of light and thermal detection.

4.
J Virol ; 96(3): e0181521, 2022 02 09.
Article in English | MEDLINE | ID: mdl-34851690

ABSTRACT

In recent years, a new class of viral noncoding subgenomic RNA (ncsgRNA) has been identified. This RNA is generated as a stable degradation product via an exoribonuclease-resistant RNA (xrRNA) structure, which blocks the progression of 5'→3' exoribonuclease on viral RNAs in infected cells. Here, we assess the effects of the ncsgRNA of red clover necrotic mosaic virus (RCNMV), called SR1f, in infected plants. We demonstrate the following: (i) the absence of SR1f reduces symptoms and decreases viral RNA accumulation in Nicotiana benthamiana and Arabidopsis thaliana plants; (ii) SR1f has an essential function other than suppression of RNA silencing; and (iii) the cytoplasmic exoribonuclease involved in mRNA turnover, XRN4, is not required for SR1f production or virus infection. A comparative transcriptomic analysis in N. benthamiana infected with wild-type RCNMV or an SR1f-deficient mutant RCNMV revealed that wild-type RCNMV infection, which produces SR1f and much higher levels of virus, has a greater and more significant impact on cellular gene expression than the SR1f-deficient mutant. Upregulated pathways include plant hormone signaling, plant-pathogen interaction, MAPK signaling, and several metabolic pathways, while photosynthesis-related genes were downregulated. We compare this to host genes known to participate in infection by other tombusvirids. Viral reads revealed a 10- to 100-fold ratio of positive to negative strand, and the abundance of reads of both strands mapping to the 3' region of RCNMV RNA1 support the premature transcription termination mechanism of synthesis for the coding sgRNA. These results provide a framework for future studies of the interactions and functions of noncoding RNAs of plant viruses. IMPORTANCE Knowledge of how RNA viruses manipulate host and viral gene expression is crucial to our understanding of infection and disease. Unlike viral protein-host interactions, little is known about the control of gene expression by viral RNA. Here, we begin to address this question by investigating the noncoding subgenomic RNA (ncsgRNA) of red clover necrotic mosaic virus (RCNMV), called SR1f. Similar exoribonuclease-resistant RNAs of flaviviruses are well studied, but the roles of plant viral ncsgRNAs, and how they arise, are poorly understood. Surprisingly, we find the likely exonuclease candidate, XRN4, is not required to generate SR1f, and we assess the effects of SR1f on virus accumulation and symptom development. Finally, we compare the effects of infection by wild-type RCNMV versus an SR1f-deficient mutant on host gene expression in Nicotiana benthamiana, which reveals that ncsgRNAs such as SR1f are key players in virus-host interactions to facilitate productive infection.


Subject(s)
Gene Expression Regulation, Viral , Genome, Viral , Plant Diseases/virology , RNA, Untranslated , RNA, Viral , Tombusviridae/physiology , Computational Biology/methods , Gene Knockdown Techniques , Gene Ontology , Host-Pathogen Interactions/genetics , Open Reading Frames , Phenotype , Plant Viruses , Transcriptome , Virus Replication
5.
Nano Lett ; 22(16): 6573-6579, 2022 Aug 24.
Article in English | MEDLINE | ID: mdl-35939658

ABSTRACT

Despite being a requisite for modern transparent electronics, few metals have a sufficiently high infrared transmittance due to the free electron response. Here, upon alloying the correlated metal SrVO3 with BaVO3, the medium wavelength infrared transmittance at a wavelength of 4 µm is found to be 50% higher than those for Sn-doped In2O3 (ITO) and La-doped BaSnO3 (BLSO). The room temperature resistivity of the alloy of ∼100 µΩ cm is 1 order of magnitude lower than those of ITO and BLSO, guaranteeing a profound electromagnetic shielding effectiveness of 22-31 dB at 10 GHz in the X-band. Systematic investigations reveal symmetry breaking of VO6 oxygen octahedra in SrVO3 due to the substitution of Sr2+ with larger Ba2+ ions, localization of electrons in the lower energy V-dyz and dzx orbitals, and stronger correlation effects. The lattice-orbital-charge-coupled engineering of the electronic band structure in correlated metals offers a new design strategy to create super-broad-band transparent conductors with an enhanced shielding capability.

6.
Plant J ; 105(5): 1179-1191, 2021 03.
Article in English | MEDLINE | ID: mdl-33231904

ABSTRACT

The exocyst is a key factor in vesicle transport and is involved in cell secretion, cell growth, cell division and other cytological processes in eukaryotes. EXO70 is the key exocyst subunit. We obtained a gene, SHORT-ROOT 1 (SR1), through map-based cloning and genetic complementation. SR1 is a conserved protein with an EXO70 domain in plants. SR1 mutation affected the whole root-development process: producing shorter radicles, adventitious roots and lateral roots, and demonstrating abnormal xylem development, resulting in dwarfing and reduced water potential and moisture content. SR1 was largely expressed in the roots, but only in developing root meristems and tracheary elements. The shortness of the sr1 mutant roots was caused by the presence of fewer meristem cells. The in situ histone H4 expression patterns confirmed that cell proliferation during root development was impaired. Tracheary element dysplasia was caused by marked decreases in the inner diameters of and distances between the perforations of adjacent tracheary elements. The membrane transport of sr1 mutants was blocked, affecting cell division in the root apical region and the development of root tracheary elements. The study of SR1 will deepen our understanding of the function of EXO70 genes in Oryza sativa (rice) and guide future studies on the molecular mechanisms involved in plant root development.


Subject(s)
Oryza/metabolism , Plant Proteins/metabolism , Plant Roots/metabolism , Gene Expression Regulation, Plant/genetics , Gene Expression Regulation, Plant/physiology , Oryza/genetics , Plant Proteins/genetics , Plant Roots/genetics , Plants, Genetically Modified/genetics , Plants, Genetically Modified/metabolism
7.
Pharmacol Res ; 177: 106132, 2022 03.
Article in English | MEDLINE | ID: mdl-35183714

ABSTRACT

Indoleamine 2,3-dioxygenase 1 (IDO1) catalyzes the rate-limiting step in tryptophan catabolism along the kynurenine (Kyn) pathway and exerts immunosuppressive properties mainly via activation of transcription factor aryl hydrocarbon receptor (AhR) pathway. IDO1 induces NK cells dysfunction via downregulation of the activating receptor NKG2D on NK cells, but whether and how it affects the expression of NKG2D Ligand (NKG2DL) on tumor cells remains unclear. Since a disintegrin and metalloprotease 10 (ADAM10) plays a potential role in the shedding of NKG2DL and the releasing of soluble NKG2DL (sNKG2DL), we investigated how IDO1 modulates the expression of NKG2DL via ADAM10 in non-small cell lung cancer (NSCLC). We found that IDO1 expression was negatively correlated with NKG2DL expression while positively correlated with ADAM10 expression with human lung cancer brain metastasis tissue, NSCLC cells and LLC tumor-bearing mice. IDO1 could regulate ADAM10 expression via IDO1-Kyn-AhR signaling pathway and subsequently regulate NKG2DL expression. IDO1 deficiency led to retarded tumor growth and improved NK cells function in NSCLC mice. IDO1 inhibitors improved NK cells function in vitro and in vivo. The combo of IDO1 inhibitor and NK cells exhibited more therapeutic efficacy than either of the single IDO1 inhibitor or NK cells treatment.


Subject(s)
Carcinoma, Non-Small-Cell Lung , Indoleamine-Pyrrole 2,3,-Dioxygenase/metabolism , Lung Neoplasms , ADAM10 Protein/metabolism , Amyloid Precursor Protein Secretases/metabolism , Animals , Carcinoma, Non-Small-Cell Lung/metabolism , Down-Regulation , Humans , Killer Cells, Natural/metabolism , Kynurenine/metabolism , Ligands , Lung Neoplasms/metabolism , Membrane Proteins/metabolism , Mice , NK Cell Lectin-Like Receptor Subfamily K/genetics , NK Cell Lectin-Like Receptor Subfamily K/metabolism
8.
Plant Cell Physiol ; 61(4): 748-760, 2020 Apr 01.
Article in English | MEDLINE | ID: mdl-31917443

ABSTRACT

Soil salinity, a prevalent abiotic stress, causes enormous losses in global crop yields annually. Previous studies have shown that salt stress-induced reprogramming of gene expression contributes to the survival of plants under this stress. However, mechanisms regulating gene expression in response to salt stress at the posttranscriptional level are not well understood. In this study, we show that salt stress increases the level of Signal Responsive 1 (SR1) mRNA, a member of signal-responsive Ca2+/calmodulin-regulated transcription factors, by enhancing its stability. We present multiple lines of evidence indicating that reactive oxygen species generated by NADPH oxidase activity mediate salt-induced SR1 transcript stability. Using mutants impaired in either nonsense-mediated decay, XRN4 or mRNA decapping pathways, we show that neither the nonsense-mediated mRNA decay pathway, XRN4 nor the decapping of SR1 mRNA is required for its decay. We analyzed the salt-induced accumulation of eight truncated versions of the SR1 coding region (∼3 kb) in the sr1 mutant background. This analysis identified a 500-nt region at the 3' end of the SR1 coding region to be required for the salt-induced stability of SR1 mRNA. Potential mechanisms by which this region confers SR1 transcript stability in response to salt are discussed.


Subject(s)
Arabidopsis Proteins/genetics , RNA, Plant/isolation & purification , Reactive Oxygen Species/metabolism , Salt Stress/genetics , Transcription Factors/genetics , Arabidopsis/genetics , Arabidopsis/metabolism , Arabidopsis Proteins/metabolism , Calmodulin/genetics , Calmodulin/metabolism , Gene Expression Regulation, Plant , Genes, Plant , NADPH Oxidases/genetics , NADPH Oxidases/metabolism , Nonsense Mediated mRNA Decay , Open Reading Frames , RNA, Messenger/genetics , RNA, Messenger/metabolism , RNA, Plant/genetics , Salinity , Salts/toxicity , Soil/chemistry , Transcription Factors/metabolism
9.
Bioprocess Biosyst Eng ; 43(11): 2027-2038, 2020 Nov.
Article in English | MEDLINE | ID: mdl-32572569

ABSTRACT

Sago hampas is a starch-based biomass from sago processing industries consisted of 58% remaining starch. This study has demonstrated the bioconversion of sago hampas to volatile fatty acids (VFAs) by Clostridium beijerinckii SR1 via anaerobic digestion. Higher total VFAs were obtained from sago hampas (5.04 g/L and 0.287 g/g) as compared to commercial starch (5.94 g/L and 0.318 g/g). The physical factors have been investigated for the enhancement of VFAs production using one-factor-at-a-time (OFAT). The optimum condition; 3% substrate concentration, 3 g/L of yeast extract concentration and 2 g/L of ammonium nitrate enhanced the production of VFAs by 52.6%, resulted the total VFAs produced is 7.69 g/L with the VFAs yield of 0.451 g/g. VFAs hydrolysate produced successfully generated 273.4 mV of open voltage circuit and 61.5 mW/m2 of power density in microbial fuel cells. It was suggested that sago hampas provide as an alternative carbon feedstock for bioelectricity generation.


Subject(s)
Bioelectric Energy Sources , Carbon/chemistry , Clostridium beijerinckii/metabolism , Fatty Acids, Volatile/biosynthesis , Industrial Microbiology/methods , Nitrogen/chemistry , Anaerobiosis , Biomass , Fermentation , Hydrogen-Ion Concentration , Hydrolysis , Starch/metabolism , Substrate Specificity
10.
Microb Pathog ; 128: 374-380, 2019 Mar.
Article in English | MEDLINE | ID: mdl-30695712

ABSTRACT

A bacterial isolate screened from wet land soil sample, found to posses antimicrobial activity against an array of fungal plant pathogens viz., Rhizoctonia solani, Sclerotium rolfsii, Alternaria solani, Fusarium oxysporum under in vitro dual culture plate assay. Further the isolate was identified into Bacillus amyloliquefaciens based on 16S rRNA sequencing. The antimicrobial fraction from the extracellular supernatant of the isolate comprises chiefly of surfactin molecules and also iturin and fengycin group of compounds. The surfactins were partially purified by tangential flow ultra-filtration and quantified with liquid chromatography yielding 316.1 mg L-1. Further the surfactin molecules were characterized by HPLC separation, FT-IR, LC-MS spectroscopy and PCR amplification of antibiotic genes. The surfactin molecule with m/z 1022 performed for MS-MS fragmentation and produced two different patterns of ion dissociation.


Subject(s)
Anti-Infective Agents/isolation & purification , Anti-Infective Agents/pharmacology , Bacillus amyloliquefaciens/isolation & purification , Bacillus amyloliquefaciens/metabolism , Lipopeptides/isolation & purification , Lipopeptides/pharmacology , Alternaria/pathogenicity , Anti-Infective Agents/chemistry , Antifungal Agents/chemistry , Antifungal Agents/isolation & purification , Antifungal Agents/pharmacology , Ascomycota/pathogenicity , Bacillus amyloliquefaciens/classification , Bacillus amyloliquefaciens/genetics , Chromatography, High Pressure Liquid , Chromatography, Liquid , DNA, Bacterial , Fusarium/pathogenicity , Genes, Bacterial/genetics , Lipopeptides/chemistry , Lipopeptides/genetics , Peptides, Cyclic/chemistry , Peptides, Cyclic/genetics , Peptides, Cyclic/isolation & purification , Peptides, Cyclic/pharmacology , Plant Diseases/microbiology , RNA, Ribosomal, 16S/genetics , Rhizoctonia/pathogenicity , Soil Microbiology , Spectroscopy, Fourier Transform Infrared , Tandem Mass Spectrometry
11.
RNA Biol ; 16(7): 972-987, 2019 07.
Article in English | MEDLINE | ID: mdl-31043113

ABSTRACT

CsrA is a widely conserved, abundant small RNA binding protein that has been found in E. coli and other Gram-negative bacteria where it is involved in the regulation of carbon metabolism, biofilm formation and virulence. CsrA binds to single-stranded GGA motifs around the SD sequence of target mRNAs where it inhibits or activates translation or influences RNA processing. Small RNAs like CsrB or CsrC containing 13-22 GGA motifs can sequester CsrA, thereby abrogating the effect of CsrA on its target mRNAs. In B. subtilis, CsrA has so far only been found to regulate one target, hag mRNA and to be sequestered by a protein (FliW) and not by an sRNA. Here, we employ a combination of in vitro and in vivo methods to investigate the effect of CsrA on the small regulatory RNA SR1 from B. subtilis, its primary target ahrC mRNA and its downstream targets, the rocABC and rocDEF operons. We demonstrate that CsrA can promote the base-pairing interactions between SR1 and ahrC mRNA, a function that has so far only been found for Hfq or ProQ. Abbreviations: aa, amino acid; bp, basepair; nt, nucleotide; PAA, polyacrylamide; SD, Shine Dalgarno.


Subject(s)
Bacillus subtilis/metabolism , Bacterial Proteins/metabolism , RNA, Bacterial/metabolism , Arginine/pharmacology , Bacillus subtilis/drug effects , Bacillus subtilis/genetics , Bacillus subtilis/growth & development , Base Pairing/genetics , Base Sequence , Carbon/pharmacology , Gene Expression Regulation, Bacterial , Mutation/genetics , Nucleic Acid Conformation , Promoter Regions, Genetic/genetics , Protein Binding , Protein Biosynthesis , RNA Stability/genetics , RNA, Bacterial/chemistry , RNA, Bacterial/genetics , RNA, Messenger/chemistry , RNA, Messenger/genetics , RNA, Messenger/metabolism , Ribonucleases/metabolism , Transcription, Genetic
12.
Luminescence ; 32(4): 612-617, 2017 Jun.
Article in English | MEDLINE | ID: mdl-27966277

ABSTRACT

In order to improve the luminescent performance of silicate blue phosphors, Sr(1.5-x)-(1.5y) Mg0.5 SiO4 :xEu2+ ,yCe3+ phosphors were synthesized using one-step calcination of a precursor prepared by chemical co-precipitation. The crystal structure and luminescent properties of the phosphors were analyzed using X-ray diffraction and fluorescence spectrophotometry, respectively. Because the activated ions (Eu2+ ) can occupy two different types of sites (Sr1 and Sr2 ), the emission spectrum of Eu2+ excited at 350 nm contains two single bands (EM1 and EM2 ) in the wavelength range 400-550 nm, centered at 463 nm, and the emission intensity first increases and then decreases with increasing concentrations of Eu2+ ions. Co-doping of Ce3+ ions can greatly enhance the emission intensity of Eu2+ by transferring its excitation energy to Eu2+ . Because of concentration quenching, a higher substitution concentration of Ce3+ can lead to a decrease in the intensity. Meanwhile, the quantum efficiency of the phosphor is improved after doping with Ce3+ , and a blue shift phenomenon is observed in the CIE chromaticity diagram. The results indicate that Sr(1.5-x)-(1.5y) Mg0.5 SiO4 :xEu2+ ,yCe3+ can be used as a potential new blue phosphor for white light-emitting diodes.


Subject(s)
Europium/chemistry , Luminescent Agents/chemistry , Cerium/chemistry , Chemical Precipitation , Crystallization , Luminescent Agents/chemical synthesis , Luminescent Measurements , Magnesium Oxide/chemistry , Silicates/chemistry , Spectrometry, Fluorescence , Strontium/chemistry , X-Ray Diffraction
13.
FEMS Microbiol Rev ; 47(6)2023 11 01.
Article in English | MEDLINE | ID: mdl-38052429

ABSTRACT

Small proteins comprising less than 100 amino acids have been often ignored in bacterial genome annotations. About 10 years ago, focused efforts started to investigate whole peptidomes, which resulted in the discovery of a multitude of small proteins, but only a number of them have been characterized in detail. Generally, small proteins can be either membrane or cytosolic proteins. The latter interact with larger proteins, RNA or even metal ions. Here, we summarize our current knowledge on small proteins from Gram-positive bacteria with a special emphasis on the model organism Bacillus subtilis. Our examples include membrane-bound toxins of type I toxin-antitoxin systems, proteins that block the assembly of higher order structures, regulate sporulation or modulate the RNA degradosome. We do not consider antimicrobial peptides. Furthermore, we present methods for the identification and investigation of small proteins.


Subject(s)
Antitoxins , Bacterial Toxins , Bacillus subtilis/genetics , Bacterial Proteins/metabolism , Bacterial Toxins/metabolism , Genome, Bacterial , Antitoxins/genetics , Antitoxins/metabolism
14.
J Mol Cell Biol ; 14(2)2022 05 20.
Article in English | MEDLINE | ID: mdl-35022784

ABSTRACT

The aryl hydrocarbon receptor (AHR) plays an important role during mammalian embryo development. Inhibition of AHR signaling promotes the development of hematopoietic stem/progenitor cells. AHR also regulates the functional maturation of blood cells, such as T cells and megakaryocytes. However, little is known about the role of AHR modulation during the development of erythroid cells. In this study, we used the AHR antagonist StemRegenin 1 (SR1) and the AHR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin during different stages of human erythropoiesis to elucidate the function of AHR. We found that antagonizing AHR signaling improved the production of human embryonic stem cell derived erythrocytes and enhanced erythroid terminal differentiation. RNA sequencing showed that SR1 treatment of proerythroblasts upregulated the expression of erythrocyte differentiation-related genes and downregulated actin organization-associated genes. We found that SR1 accelerated F-actin remodeling in terminally differentiated erythrocytes, favoring their maturation of the cytoskeleton and enucleation. We demonstrated that the effects of AHR inhibition on erythroid maturation were associated with F-actin remodeling. Our findings help uncover the mechanism for AHR-mediated human erythroid cell differentiation. We also provide a new approach toward the large-scale production of functionally mature human pluripotent stem cell-derived erythrocytes for use in translational applications.


Subject(s)
Actins , Receptors, Aryl Hydrocarbon , Actins/metabolism , Animals , Cell Differentiation/genetics , Erythroblasts/metabolism , Hematopoietic Stem Cells , Humans , Mammals , Receptors, Aryl Hydrocarbon/genetics , Receptors, Aryl Hydrocarbon/metabolism
15.
ACS Appl Mater Interfaces ; 14(43): 48821-48832, 2022 Nov 02.
Article in English | MEDLINE | ID: mdl-36266254

ABSTRACT

High-performance Sr1-xErxTiO3 (x = 0-0.014) ceramics were sintered in different atmospheres using the conventional solid-state reaction method. The phase structure and micromorphology of ceramics were analyzed using X-ray diffraction and scanning electron microscopy. Meanwhile, the Sr1-xErxTiO3 (when x = 0.012) ceramic sintered in hydrogen attains a colossal permittivity (132 543 @1 kHz, 157 650 @1 MHz) and ultralow tan δ (0.009 @1 kHz, 0.03 @1 MHz) and has good frequency stability (20 Hz to 2 MHz) and temperature stability (-180 to 425 °C). X-ray photoelectron spectroscopy, electron paramagnetic resonance, and impedance analysis show that the colossal permittivity and ultralow dielectric loss are attributed to the defect dipoles and defect clusters [TiTi'-VO••-TiTi'], [ErSr•-TiTi'], [2ErTi'-VO••], and [ErSr•-ErTi']. The insulation resistivity is determined by the grain boundary. The dielectric properties of samples sintered in hydrogen are excellent, and then, the oxidation method is used to backfill the oxygen vacancy (VO••), thus improving the insulation resistivity (2.8 × 1014 Ω cm) of the grain boundary. In addition, the diffusion mechanism of ceramic VO•• from low, medium, and high temperatures was studied by monitoring VO•• behavior in real time. The results reveal that the diffusion coefficient of VO•• in the grain boundary is greater than that in the grain; as a result, as the external oxygen partial pressure rises, the VO•• escapes first from the grain boundary. When the external oxygen partial pressure decreases, oxygen atoms enter the grain boundary region first and backfill oxygen vacancies.

16.
Micromachines (Basel) ; 13(11)2022 Oct 26.
Article in English | MEDLINE | ID: mdl-36363845

ABSTRACT

Low loss Ruddlesden-Popper (RP) series, i.e., (Sr1-xCax)5Ti4O13, 0.0 ≤ x ≤ 0.06, has been synthesized by a mixed oxide route. In this work, the substitution of Ca2+ cation in Sr5Ti4O13 sintered ceramics was chosen to enhance the structural, optical, and dielectric properties of the product. It was found that the Ca2+ content has significant effects on enhancing the dielectric properties as compared to Mn and glass additions. It was observed that the relative density, band gap energy, and dielectric loss (tangent loss) increase while relative permittivity decreases along with Ca2+ content. High relative density (96.7%), low porosity, and high band gap energy (2.241 eV) values were obtained in (Sr1-xCax)5Ti4O13, 0.0 ≤ x ≤ 0.06 sintered ceramics. These results will play a key role in the application of dielectric resonators.

17.
Microorganisms ; 9(9)2021 Sep 02.
Article in English | MEDLINE | ID: mdl-34576762

ABSTRACT

Small regulatory RNAs (sRNAs) that act by base-pairing are the most abundant posttranscriptional regulators in all three kingdoms of life. Over the past 20 years, a variety of approaches have been employed to discover chromosome-encoded sRNAs in a multitude of bacterial species. However, although largely improved bioinformatics tools are available to predict potential targets of base-pairing sRNAs, it is still challenging to confirm these targets experimentally and to elucidate the mechanisms as well as the physiological role of their sRNA-mediated regulation. Here, we provide an overview of currently known cis- and trans-encoded sRNAs from B. subtilis with known targets and defined regulatory mechanisms and on the potential role of RNA chaperones that are or might be required to facilitate sRNA regulation in this important Gram-positive model organism.

18.
Microorganisms ; 9(5)2021 May 12.
Article in English | MEDLINE | ID: mdl-34066298

ABSTRACT

Moonlighting proteins are proteins with more than one function. During the past 25 years, they have been found to be rather widespread in bacteria. In Bacillus subtilis, moonlighting has been disclosed to occur via DNA, protein or RNA binding or protein phosphorylation. In addition, two metabolic enzymes, enolase and phosphofructokinase, were localized in the degradosome-like network (DLN) where they were thought to be scaffolding components. The DLN comprises the major endoribonuclease RNase Y, 3'-5' exoribonuclease PnpA, endo/5'-3' exoribonucleases J1/J2 and helicase CshA. We have ascertained that the metabolic enzyme GapA is an additional component of the DLN. In addition, we identified two small proteins that bind scaffolding components of the degradosome: SR1P encoded by the dual-function sRNA SR1 binds GapA, promotes the GapA-RNase J1 interaction and increases the RNase J1 activity. SR7P encoded by the dual-function antisense RNA SR7 binds to enolase thereby enhancing the enzymatic activity of enolase bound RNase Y. We discuss the role of small proteins in modulating the activity of two moonlighting proteins.

19.
AAS Open Res ; 3: 22, 2020.
Article in English | MEDLINE | ID: mdl-33842833

ABSTRACT

Background: Malaria remains a global challenge with approximately 228 million cases and 405,000 malaria-related deaths reported in 2018 alone; 93% of which were in sub-Saharan Africa. Aware of the critical role than environmental factors play in malaria transmission, this study aimed at assessing the relationship between precipitation, temperature, and clinical malaria cases in East Africa and how the relationship may change under 1.5 oC and 2.0 oC global warming levels (hereinafter GWL1.5 and GWL2.0, respectively). Methods: A correlation analysis was done to establish the current relationship between annual precipitation, mean temperature, and clinical malaria cases. Differences between annual precipitation and mean temperature value projections for periods 2008-2037 and 2023-2052 (corresponding to GWL1.5 and GWL2.0, respectively), relative to the control period (1977-2005), were computed to determine how malaria transmission may change under the two global warming scenarios. Results: A predominantly positive/negative correlation between clinical malaria cases and temperature/precipitation was observed. Relative to the control period, no major significant changes in precipitation were shown in both warming scenarios. However, an increase in temperature of between 0.5 oC and 1.5 oC and 1.0 oC to 2.0 oC under GWL1.5 and GWL2.0, respectively, was recorded. Hence, more areas in East Africa are likely to be exposed to temperature thresholds favourable for increased malaria vector abundance and, hence, potentially intensify malaria transmission in the region. Conclusions: GWL1.5 and GWL2.0 scenarios are likely to intensify malaria transmission in East Africa. Ongoing interventions should, therefore, be intensified to sustain the gains made towards malaria elimination in East Africa in a warming climate.

20.
Beilstein J Nanotechnol ; 11: 651-661, 2020.
Article in English | MEDLINE | ID: mdl-32363131

ABSTRACT

We studied in detail the in-plane magnetic properties of heterostructures based on a ferroelectric BaTiO3 overlayer deposited on a ferromagnetic La2/3Sr1/3MnO3 film grown epitaxially on pseudocubic (001)-oriented SrTiO3, (LaAlO3)0.3(Sr2TaAlO6)0.7 and LaAlO3 substrates. In this configuration, the combination of both functional perovskites constitutes an artificial multiferroic system with potential applications in spintronic devices based on the magnetoelectric effect. La2/3Sr1/3MnO3 single layers and BaTiO3/La2/3Sr1/3MnO3 bilayers using the pulsed-laser deposition technique. We analyzed the films structurally through X-ray reciprocal space maps and high-angle annular dark field microscopy, and magnetically via thermal demagnetization curves and in-plane magnetization versus applied magnetic field loops at room temperature. Our results indicate that the BaTiO3 layer induces an additional strain in the La2/3Sr1/3MnO3 layers close to their common interface. The presence of BaTiO3 on the surface of tensile-strained La2/3Sr1/3MnO3 films transforms the in-plane biaxial magnetic anisotropy present in the single layer into an in-plane uniaxial magnetic anisotropy. Our experimental evidence suggests that this change in the magnetic anisotropy only occurs in tensile-strained La2/3Sr1/3MnO3 film and is favored by an additional strain on the La2/3Sr1/3MnO3 layer promoted by the BaTiO3 film. These findings reveal an additional mechanism that alters the magnetic behavior of the ferromagnetic layer, and consequently, deserves further in-depth research to determine how it can modify the magnetoelectric coupling of this hybrid multiferroic system.

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