2494 research outputs found
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A High-Efficiency Si Nanowire Array/Perovskite Hybrid Solar Cell
No full textAbstract
A low-cost Si nanowire array/perovskite hybrid solar cell is proposed and simulated. The solar cell consists of a Si p-i-n nanowire array filled with CH
3
NH
3
PbI
3
, in which both the nanowires and perovskite absorb the incident light while the nanowires act as the channels for transporting photo-generated electrons and holes. The hybrid structure has a high absorption efficiency in a broad wavelength range of 300~800\ua0nm. A large short-circuit current density of 28.8\ua0mA/cm
2
and remarkable conversion efficiency of 13.3% are obtained at a thin absorber thickness of 1.6\ua0\u3bcm, which are comparable to the best results of III\u2013V nanowire solar cells.
PACS: 62.23.Hj, 84.60.Jt, 61.72.uf
Synthesis of ZnO/Si Hierarchical Nanowire Arrays for Photocatalyst Application
No full textAbstract
ZnO/Si nanowire arrays with hierarchical architecture were synthesized by solution method with ZnO seed layer grown by atomic layer deposition and magnetron sputtering, respectively. The photocatalytic activity of the as-grown tree-like arrays was evaluated by the degradation of methylene blue under ultraviolet light at ambient temperature. The comparison of morphology, crystal structure, optical properties, and photocatalysis efficiency of the two samples in different seeding processes was conducted. It was found that the ZnO/Si nanowire arrays presented a larger surface area with better crystalline and more uniform ZnO branches on the whole sidewall of Si backbones for the seed layer by atomic layer deposition, which gained a strong light absorption as high as 98% in the ultraviolet and visible range. The samples were proven to have a potential use in photocatalyst, but suffered from photodissolution and memory effect. The mechanism of the photocatalysis was analyzed, and the stability and recycling ability were also evaluated and enhanced
Large-scale transcriptome comparison of sunflower genes responsive to Verticillium dahliae
No full textAbstract
Background
Sunflower Verticillium wilt (SVW) is a vascular disease caused by root infection with Verticillium dahliae (V. dahlia) . It is a serious threat to the yield and quality of sunflower. However, chemical and agronomic measures for controlling this disease are not effective. The selection of more resistant genotypes is a desirable strategy to reduce contamination. A deeper knowledge of the molecular mechanisms and genetic basis underlying sunflower Verticillium wilt is necessary to accelerate breeding progress.
Results
An RNA-Seq approach was used to perform global transcriptome profiling on the roots of resistant (S18) and susceptible (P77) sunflower genotypes infected with V. dahlia . Different pairwise transcriptome comparisons were examined over a time course (6, 12 and 24\ua0h, and 2, 3, 5 and 10 d post inoculation). In RD, SD and D datasets, 1231 genes were associated with SVW resistance in a genotype-common transcriptional pattern. Moreover, 759 and 511 genes were directly related to SVW resistance in the resistant and susceptible genotypes, respectively, in a genotype-specific transcriptional pattern. Most of the genes were demonstrated to participate in plant defense responses; these genes included peroxidase (POD), glutathione peroxidase, aquaporin PIP, chitinase, L-ascorbate oxidase, and LRR receptors. For the up-regulated genotype-specific differentially expressed genes (DEGs) in the resistant genotype, higher average fold-changes were observed in the resistant genotype compared to those in the susceptible genotype. An inverse effect was observed in the down-regulated genotype-specific DEGs in the resistant genotype. KEGG analyses showed that 98, 112 and 52 genes were classified into plant hormone signal transduction, plant-pathogen interaction and flavonoid biosynthesis categories, respectively. Many of these genes, such as CNGC, RBOH, FLS2, JAZ, MYC2 NPR1 and TGA, regulate crucial points in defense-related pathway and may contribute to V. dahliae resistance in sunflower.
Conclusions
The transcriptome profiling results provided a clearer understanding of the transcripts associated with the crosstalk between sunflower and V. dahliae . The results identified several differentially expressed unigenes involved in the hyper sensitive response (HR) and the salicylic acid (SA)/jasmonic acid (JA)-mediated signal transduction pathway for resistance against V. dahliae . These results are useful for screening resistant sunflower genotypes
Organelle_PBA, a pipeline for assembling chloroplast and mitochondrial genomes from PacBio DNA sequencing data
No full textAbstract
Background
The development of long-read sequencing technologies, such as single-molecule real-time (SMRT) sequencing by PacBio, has produced a revolution in the sequencing of small genomes. Sequencing organelle genomes using PacBio long-read data is a cost effective, straightforward approach. Nevertheless, the availability of simple-to-use software to perform the assembly from raw reads is limited at present.
Results
We present Organelle-PBA, a Perl program designed specifically for the assembly of chloroplast and mitochondrial genomes. For chloroplast genomes, the program selects the chloroplast reads from a whole genome sequencing pool, maps the reads to a reference sequence from a closely related species, and then performs read correction and de novo assembly using Sprai. Organelle-PBA completes the assembly process with the additional step of scaffolding by SSPACE-LongRead. The program then detects the chloroplast inverted repeats and reassembles and re-orients the assembly based on the organelle origin of the reference. We have evaluated the performance of the software using PacBio reads from different species, read coverage, and reference genomes. Finally, we present the assembly of two novel chloroplast genomes from the species Picea glauca (Pinaceae) and Sinningia speciosa (Gesneriaceae).
Conclusion
Organelle-PBA is an easy-to-use Perl-based software pipeline that was written specifically to assemble mitochondrial and chloroplast genomes from whole genome PacBio reads. The program is available at https://github.com/aubombarely/Organelle_PBA
Elucidation of the molecular responses of a cucumber segment substitution line carrying Pm5.1 and its recurrent parent triggered by powdery mildew by comparative transcriptome profiling
No full textAbstract
Background
Powdery mildew (PM) is one of the most severe fungal diseases of cucurbits, but the molecular mechanisms underlying PM resistance in cucumber remain elusive. In this study, we developed a PM resistant segment substitution line SSL508-28 that carried a segment on chromosome five representing the Pm5.1 locus from PM resistant donor Jin5-508 using marker-assisted backcrossing of an elite PM susceptible cucumber inbred line D8.
Results
Whole-genome resequencing of SSL508-28, Jin5-508 and D8 was performed to identify the exact boundaries of the breakpoints for this introgression because of the low density of available single sequence repeat markers. This led to the identification of a ~6.8\ua0Mb substituted segment predicted to contain 856 genes. RNA-seq was used to study gene expression differences in PM treated (plants harvested 48\ua0h after inoculation) and untreated (control) SSL508-28 and D8 lines. Exactly 1,248 and 1,325 differentially expressed genes (DEGs) were identified in SSL508-28 and D8, respectively. Of those, 88 DEGs were located in the ~6.8\ua0Mb segment interval. Based on expression data and annotation, we identified 8 potential candidate genes that may participate in PM resistance afforded by Pm5.1 , including two tandemly arrayed genes encoding receptor protein kinases, two transcription factors, two genes encoding remorin proteins, one gene encoding a P-type ATPase and one gene encoding a 70\ua0kDa heat shock protein. The transcriptome data also revealed a complex regulatory network for Pm5.1 -mediated PM resistance that may involve multiple signal regulators and transducers, cell wall modifications and the salicylic acid signaling pathway.
Conclusion
These findings shed light on the cucumber PM defense mechanisms mediated by Pm5.1 and provided valuable information for the fine mapping of Pm5.1 and breeding of cucumber with enhanced resistance to PM
Oxidative stress biomarkers and their relationship with cytokine concentrations in overweight/obese pregnant women and their neonates
No full textAbstract
Background
Oxidative damage present in obese/overweight mothers may lead to further oxidative stress conditions or inflammation in maternal and cord blood samples. Thirty-four pregnant women/newborn pairs were included in this study to assess the presence of oxidative stress biomarkers and their relationship with serum cytokine concentrations. Oxidative stress biomarkers and antioxidant enzymes were compared between the mother/offspring pairs. The presence of 27 cytokines was measured in maternal and cord blood samples. Analyses were initially performed between all mothers and newborns and later between normal weight and mothers with overweight and obesity, and diabetic/non-diabetic women.
Results
Significant differences were found in biomarker concentrations between mothers and newborns. Additionally, superoxide-dismutase activity was higher in pre-pregnancy overweight mothers compared to those with normal weight. Activity for this enzyme was higher in neonates born from mothers with normal pregestational weight compared with their mothers. Nitrites in overweight/obese mothers were statistically lower than in their offspring. Maternal free fatty acids, nitrites, carbonylated proteins, malondialdehyde and superoxide dismutase predicted maternal serum concentrations of IL-4, IL-13, IP-10 and MIP-1\u3b2. Arginase activity in maternal plasma was related to decreased concentrations of IL-4 and IL-1\u3b2 in cord arterial blood. Increased maternal malondialdehyde plasma was associated with higher levels of IL-6 and IL-7 in the offspring.
Conclusions
Oxidative stress biomarkers differ between mothers and offspring and can predict maternal and newborn cytokine concentrations, indicating a potential role for oxidative stress in foetal metabolic and immunologic programming. Moreover, maternal obesity and diabetes may affect maternal microenvironments, and oxidative stress related to these can have an impact on the placenta and foetal growth
Porphyromonas gingivalis activates NF\u3baB and MAPK pathways in human oral epithelial cells
No full textAbstract
Background
The bacterial biofilm at the gingival margin induces a host immune reaction. In this local inflammation epithelial cells defend the host against bacterial challenge. Porphyromonas gingivalis ( P. gingivalis ), a keystone pathogen, infects epithelial cells. The aim of this study was to investigate the activation of signaling cascades in primary epithelial cells and oral cancer cell lines by a profiler PCR array.
Results
After infection with P. gingivalis membranes the RNA\ufeff of \ufeff16 to 33 of 84 key genes involved in the antibacterial immune response was up-regulated, amongst them were IKBKB (NF-\u3baB signaling pathway), IRF5 (TLR signaling) and JUN, MAP2K4, MAPK14 and MAPK8 (MAPK pathway) in SCC-25 cells and IKBKB, IRF5, JUN, MAP2K4, MAPK14 and MAPK8 in PHGK. Statistically significant up-regulation of IKBKB (4.7 \ud7), MAP2K4 (4.6 \ud7), MAPK14 (4.2 \ud7) and IRF5 (9.8 \ud7) ( p \u2009<\u20090.01) was demonstrated in SCC-25 cells and IKBKB (3.1 \ud7), MAP2K4 (4.0 \ud7) MAPK 14 (3.0 \ud7) ( p \u2009<\u20090.05), IRF5 (3.0 \ud7) and JUN (7.7 \ud7) ( p \u2009<\u20090.01) were up-regulated in PHGK.
Conclusions
P. gingivalis membrane up-regulates the expression of genes involved in downstream TLR, NF\u3baB and MAPK signaling pathways involved in the pro-inflammatory immune response in primary and malignant oral epithelial cells
Evaluation of MLVA for epidemiological typing and outbreak detection of ESBL-producing Escherichia coli in Sweden
No full textAbstract
Background
To identify the spread of nosocomial infections and halt outbreak development caused by Escherichia coli that carry multiple antibiotic resistance factors, such as extended-spectrum beta-lactamases (ESBLs) and carbapenemases, is becoming demanding challenges due to the rapid global increase and constant and increasing influx of these bacteria from the community to the hospital setting. Our aim was to assess a reliable and rapid typing protocol for ESBL- E. coli , with the primary focus to screen for possible clonal relatedness between isolates. All clinical ESBL- E. coli isolates, collected from hospitals ( n \u2009=\u200963) and the community ( n \u2009=\u200941), within a single geographical region over a 6\ua0months period, were included, as well as clinical isolates from a polyclonal outbreak (ST131, n \u2009=\u20099, and ST1444, n \u2009=\u20093). The sporadic cases represented 36 STs, of which eight STs dominated i.e. ST131 ( n \u2009=\u200933 isolates), ST648 ( n \u2009=\u200910), ST38 ( n \u2009=\u20099), ST12 and 69 (each n \u2009=\u20094), ST 167, 405 and 372 (each n \u2009=\u20093). The efficacy of multiple-locus variable number tandem repeat analysis (MLVA) was evaluated using three, seven or ten loci, in comparison with that of pulsed-field gel electrophoresis (PFGE) and multi locus sequence typing (MLST).
Results
MLVA detected 39, 55 and 60 distinct types, respectively, using three (GECM-3), seven (GECM-7) or ten (GECM-10) loci. For GECM-7 and \u221210, 26 STs included one type and eleven STs each included several types, the corresponding numbers for GECM-3 were 29 and 8. The highest numbers were seen for ST131 (7,7 and 8 types, respectively), ST38 (5,5,8) and ST648 (4,5,5). Good concordance was observed with PFGE and GECM-7 and \u221210, despite fewer types being identified with MLVA; 78 as compared to 55 and 60 types. The lower discriminatory power of MLVA was primarily seen within the O25b-ST131 lineage ( n \u2009=\u200934) and its H30-Rx subclone ( n \u2009=\u200921). Epidemiologically unrelated O25b-ST131 isolates were clustered with O25b-ST131 outbreak isolates by MLVA, whereas the ST1444 outbreak isolates were accurately distinguished from unrelated isolates.
Conclusion
MLVA, even when using only three loci, represents an easy initial typing tool for epidemiological screening of ESBL- E. coli . For the ST131-O25b linage, complementary methods may be needed to obtain sufficient resolution
Identification of brassinosteroid genes in Brachypodium distachyon
No full textAbstract
Background
Brassinosteroids (BRs) are steroidal phytohormones that are involved in diverse physiological processes and affect many important traits, such as plant stature, stress tolerance, leaf angle, fertility, and grain filling. BR signaling and biosynthetic pathways have been studied in various plants, such as the model dicot Arabidopsis thaliana ; however, relatively little is known about these pathways in monocots.
Results
To characterize BR-related processes in the model grass Brachypodium distachyon , we studied the response of these plants to the specific BR biosynthesis inhibitor, propiconazole (Pcz). We found that treatments with Pcz produced a dwarf phenotype in B. distachyon seedlings, similar to that observed in Pcz-treated Arabidopsis plants and in characterized BR-deficient mutants. Through bioinformatics analysis, we identified a list of putative homologs of genes known to be involved in BR biosynthesis and signaling in Arabidopsis, such as DWF4 , BR6OX2 , CPD , BRI1 , and BIN2 . Evaluating the response of these genes to Pcz treatments revealed that candidates for BdDWF4 , BR6OX2 and, CPD were under feedback regulation. In addition, Arabidopsis plants heterologously expressing BdDWF4 displayed tall statures and elongated petioles, as would be expected in plants with elevated levels of BRs. Moreover, heterologous expression of BdBIN2 in Arabidopsis resulted in dwarfism, suggesting that BdBIN2 functions as a negative regulator of BR signaling. However, the dwarf phenotypes of Arabidopsis bri1-5 , a weak BRI1 mutant allele, were not complemented by overexpression of BdBRI1 , indicating that BdBRI1 and BRI1 are not functionally equivalent.
Conclusion
We identified components of the BR biosynthetic and signaling pathways in Brachypodium, and provided examples of both similarities and differences in the BR biology of these two plants. Our results suggest a framework for understanding BR biology in monocot crop plants such as Zea mays (maize) and Oryza sativa (rice)
Bleeding outcomes associated with rivaroxaban and dabigatran in patients treated for atrial fibrillation: a systematic review and meta-analysis
No full textAbstract
Background
Warfarin is commonly used as a secondary prevention of stroke in patients with atrial fibrillation (AF). However, limitations have been observed even with the use of this medication. Recently, several newer direct oral anticoagulants (DOACs) have been approved for use by the food and drug administrations. Unfortunately, these newer drugs have seldom been compared directly with each other. Therefore, this study aimed to compare the bleeding events associated with rivaroxaban and dabigatran in patients treated for non-valvular AF.
Methods
EMBASE, Medline (National Library of Medicine) and the Cochrane Central Registry of Controlled Trials were searched for studies comparing rivaroxaban with dabigatran using the terms \u2018rivaroxaban, dabigatran and atrial fibrillation\u2019. Primary endpoints were: any bleeding outcomes, intracranial bleeding and gastro-intestinal (GI) bleeding. Secondary outcomes included stroke/systemic embolism (SE)/transient ischemic attack (TIA), venous thromboembolism and mortality. Odds ratios (OR) with 95% confidence intervals (CIs) were calculated. The pooled analyses were carried out with RevMan 5.3 software. All the authors had full access to the data and approved the manuscript as written.
Results
A total number of 4895 patients were included. This analysis showed that rivaroxaban was not associated with a significantly higher bleeding event when compared to dabigatran (OR: 1.28, 95% CI: 0.95\u20131.72; P \u2009=\u20090.11). GI bleeding was similarly manifested between these two DOACs (OR: 0.98, 95% CI: 0.43\u20132.25; P \u2009=\u20090.97). Even if intracranial bleeding was higher with the use of rivaroxaban, (OR: 2.18, 95% CI: 0.51\u20139.25; P \u2009=\u20090.29), the result was not statistically significant. Moreover, stroke/SE/TIA and venous thromboembolism were also not significantly different (OR: 0.81, 95% CI: 0.53\u20131.23; P \u2009=\u20090.32) and (OR: 2.06, 95% CI: 0.73\u20135.82; P \u2009=\u20090.17) respectively. However, even if mortality favored dabigatran (OR: 1.42, 95% CI: 0.99\u20132.06; P \u2009=\u20090.06), this result only approached statistical significance.
Conclusion
Head to head comparison showed that rivaroxaban was not associated with significantly higher bleeding events compared to dabigatran. Intracranial bleeding, GI bleeding, stroke/SE/TIA, venous thromboembolism and mortality were also not significantly different between these two DOACs. However, due to the ..