Gestational intermittent hypoxia induces endothelial dysfunction and hypertension in pregnant rats: role of endothelin type B receptor†.

Obstructive sleep apnea is a recognized risk factor for gestational hypertension, yet the exact mechanism behind this association remains unclear. Here, we tested the hypothesis that intermittent hypoxia, a hallmark of obstructive sleep apnea, induces gestational hypertension through perturbed endothelin-1 signaling. Pregnant Sprague-Dawley rats were subjected to normoxia (control), mild intermittent hypoxia (10.5% O2), or severe intermittent hypoxia (6.5% O2) from gestational days 10-21. Blood pressure was monitored. Plasma was collected and mesenteric arteries were isolated for myograph and protein analyses. The mild and severe intermittent hypoxia groups demonstrated elevated blood pressure, reduced plasma nitrate/nitrite, and unchanged endothelin-1 levels compared to the control group. Western blot analysis revealed decreased expression of endothelin type B receptor and phosphorylated endothelial nitric oxide synthase, while the levels of endothelin type A receptor and total endothelial nitric oxide synthase remained unchanged following intermittent hypoxia exposure. The contractile responses to potassium chloride, phenylephrine, and endothelin-1 were unaffected in endothelium-denuded arteries from mild and severe intermittent hypoxia rats. However, mild and severe intermittent hypoxia rats exhibited impaired endothelium-dependent vasorelaxation responses to endothelin type B receptor agonist IRL-1620 and acetylcholine compared to controls. Endothelium denudation abolished IRL-1620-induced vasorelaxation, supporting the involvement of endothelium in endothelin type B receptor-mediated relaxation. Treatment with IRL-1620 during intermittent hypoxia exposure significantly attenuated intermittent hypoxia-induced hypertension in pregnant rats. This was associated with elevated circulating nitrate/nitrite levels, enhanced endothelin type B receptor expression, increased endothelial nitric oxide synthase activation, and improved vasodilation responses. Our data suggested that intermittent hypoxia exposure during gestation increases blood pressure in pregnant rats by suppressing endothelin type B receptor-mediated signaling, providing a molecular mechanism linking intermittent hypoxia and gestational hypertension.

H2S Donor GYY4137 Mitigates sFlt-1-Induced Hypertension and Vascular Dysfunction in Pregnant Rats.

BACKGROUND: Gestational hypertension, often associated with elevated soluble Fms-related receptor tyrosine kinase 1 (sFlt-1), poses significant risks to both maternal and fetal health. Hydrogen sulfide (H2S), a gasotransmitter, has demonstrated blood pressure-lowering effects in hypertensive animals and humans. However, its role in pregnancy-induced hypertension remains unclear. OBJECTIVE: This study aimed to investigate the impact of GYY4137, a slow-release H2S donor, on sFlt-1-induced hypertension in pregnant rats and examine the underlying mechanisms. METHODS: Pregnant rats were administered sFlt-1 (6 µg/kg/day, intravenously) or vehicle from gestation day (GD) 12 to 20. A subset of these groups received GYY4137 (an H2S donor, 50 mg/kg/day, subcutaneously) from GD 16 to 20. Serum H2S levels, mean arterial blood pressure (CODA tail-cuff), uterine artery blood flow (ultrasonography), vascular reactivity to vasopressors and endothelial-dependent relaxation (myography), endothelial nitric oxide synthase (eNOS) protein expression in uterine arteries (Western blotting) were assessed. In addition, maternal weight gain, as well as fetal and placental weights, were measured. RESULTS: Elevated sFlt-1 reduced both maternal weight gain and serum H2S levels. GYY4137 treatment restored both weight gain and H2S levels in sFlt-1 dams. sFlt-1 increased mean arterial pressure and decreased uterine artery blood flow in pregnant rats. However, treatment with GYY4137 normalized blood pressure and restored uterine blood flow in sFlt-1 dams. sFlt-1 dams exhibited heightened vasoconstriction to phenylephrine and GYY4137 significantly mitigated the exaggerated vascular contraction. Notably, sFlt-1 impaired endothelium-dependent relaxation, while GYY4137 attenuated this impairment by upregulating eNOS protein levels and enhancing vasorelaxation in uterine arteries. GYY4137 mitigated sFlt-1-induced fetal growth restriction. CONCLUSION: sFlt-1 mediated hypertension is associated with decreased H2S levels. Replenishing H2S with the donor GYY4137 mitigates hypertension and improves vascular function and fetal growth outcomes. This suggests modulation of H2S could offer a novel therapeutic strategy for managing gestational hypertension and adverse fetal effects.

Male infertility and Perfluoroalkyl and poly-fluoroalkyl substances: Evidence for alterations in phosphorylation of proteins and fertility-related functional attributes in bull spermatozoa.

BACKGROUND: Perfluoroalkyl and poly-fluoroalkyl substances (PFAS) are pervasive environmental pollutants and emerging risk factors for reproductive health. Although epidemiological evidence supports the link between these substances and male infertility, their specific effects on male fertility remain poorly understood. OBJECTIVES: Investigate the effect of perfluorooctane sulfonic acid (PFOS), the most prevalent and prominent PFAS, on bull sperm protein phosphorylation, a post-translational modification process governing sperm functionality and fertility. METHODS: We exposed bull sperm to PFOS at 10 µM (average population level) and 100 µM (high-exposure level), and analyzed global proteome and phosphoproteome profile by TMT labeling and NanoLC-MS/MS. We also measured sperm fertility functions by flow cytometry. RESULTS: PFOS at 10 µM altered sperm proteins linked to spermatogenesis and chromatin condensation, while at 100 µM, PFOS affected proteins associated with motility and fertility. We detected 299 phosphopeptides from 116 proteins, with 45 exhibiting differential expression between control and PFOS groups. PFOS dysregulated phosphorylation of key proteins (ACRBP, PRKAR2A, RAB2B, SPAG8, TUBB4B, ZPBP, and C2CD6) involved in sperm capacitation, acrosome reaction, sperm-egg interaction, and fertilization. PFOS also affected phosphorylation of other proteins (AQP7, HSBP9, IL4I1, PRKAR1A, and CCT8L2) related to sperm stress resistance and cryotolerance. Notably, 4 proteins (PRM1, ACRBP, TSSK1B, and CFAP45) exhibited differential regulation at both the proteomic and phosphoproteomic levels. Flow cytometric analysis confirmed that PFOS increased protein phosphorylation in sperm as well as reduced sperm motility, viability, calcium, and membrane potential and increased mitochondrial ROS in a dose-dependent manner. CONCLUSIONS: This study shows that PFOS exposure adversely impacts phosphorylation of proteins critical for bull sperm function and fertilization. Moreover, the concentration of PFOS influences the severity of these effects. The comprehensive bull sperm phosphoproteomics data from this study can help us understand the molecular mechanisms of environmental exposure-related male infertility.

Peribacillus frigoritolerans T7-IITJ, a potential biofertilizer, induces plant growth-promoting genes of Arabidopsis thaliana.

AIMS: This study aimed to isolate plant growth and drought tolerance-promoting bacteria from the nutrient-poor rhizosphere soil of Thar desert plants and unravel their molecular mechanisms of plant growth promotion. METHODS AND RESULTS: Among our rhizobacterial isolates, Enterobacter cloacae C1P-IITJ, Kalamiella piersonii J4-IITJ, and Peribacillus frigoritolerans T7-IITJ, significantly enhanced root and shoot growth (4-5-fold) in Arabidopsis thaliana under PEG-induced drought stress. Whole genome sequencing and biochemical analyses of the non-pathogenic bacterium T7-IITJ revealed its plant growth-promoting traits, viz., solubilization of phosphate (40-73 µg/ml), iron (24 ± 0.58 mm halo on chrome azurol S media), and nitrate (1.58 ± 0.01 µg/ml nitrite), along with production of exopolysaccharides (125 ± 20 µg/ml) and auxin-like compounds (42.6 ± 0.05 µg/ml). Transcriptome analysis of A. thaliana inoculated with T7-IITJ and exposure to drought revealed the induction of 445 plant genes (log2fold-change > 1, FDR < 0.05) for photosynthesis, auxin and jasmonate signalling, nutrient uptake, redox homeostasis, and secondary metabolite biosynthesis pathways related to beneficial bacteria-plant interaction, but repression of 503 genes (log2fold-change < -1) including many stress-responsive genes. T7-IITJ enhanced proline 2.5-fold, chlorophyll 2.5-2.8-fold, iron 2-fold, phosphate 1.6-fold, and nitrogen 4-fold, and reduced reactive oxygen species 2-4.7-fold in plant tissues under drought. T7-IITJ also improved the germination and seedling growth of Tephrosia purpurea, Triticum aestivum, and Setaria italica under drought and inhibited the growth of two plant pathogenic fungi, Fusarium oxysporum, and Rhizoctonia solani. CONCLUSIONS: P. frigoritolerans T7-IITJ is a potent biofertilizer that regulates plant genes to promote growth and drought tolerance.

Effects of metformin on cancers in experimental and clinical studies: Focusing on autophagy and AMPK/mTOR signaling pathways.

Metformin (MET) is a preferred drug for the treatment of type 2 diabetes mellitus. Recent studies show that apart from its blood glucose-lowering effects, it also inhibits the development of various tumours, by inducing autophagy. Various studies have confirmed the inhibitory effects of MET on cancer cell lines' propagation, migration, and invasion. The objective of the study was to comprehensively review the potential of MET as an anticancer agent, particularly focusing on its ability to induce autophagy and inhibit the development and progression of various tumors. The study aimed to explore the inhibitory effects of MET on cancer cell proliferation, migration, and invasion, and its impact on key signaling pathways such as adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and PI3K. This review noted that MET exerts its anticancer effects by regulating key signalling pathways such as phosphoinositide 3-kinase (PI3K), LC3-I and LC3-II, Beclin-1, p53, and the autophagy-related gene (ATG), inhibiting the mTOR protein, downregulating the expression of p62/SQSTM1, and blockage of the cell cycle at the G0/G1. Moreover, MET can stimulate autophagy through pathways associated with the 5' AMPK, thereby inhibiting he development and progression of various human cancers, including hepatocellular carcinoma, prostate cancer, pancreatic cancer, osteosarcoma, myeloma, and non-small cell lung cancer. In summary, this detailed review provides a framework for further investigations that may appraise the autophagy-induced anticancer potential of MET and its repurposing for cancer treatment.

Single-cell transcriptome analysis identifies novel biomarkers involved in major liver cancer subtypes.

Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) are the two aggressive subtypes of liver cancer (LC). Immense cellular heterogeneity and cross-talk between cancer and healthy cells make it challenging to treat these cancer subtypes. To address these challenges, the study aims to systematically characterize the tumor heterogeneity of LC subtypes using single-cell RNA sequencing (scRNA-seq) datasets. The study combined 51,927 single cells from HCC, ICC, and healthy scRNA-seq datasets. After integrating the datasets, cell groups with similar gene expression patterns are clustered and cluster annotation has been performed based on gene markers. Cell-cell communication analysis (CCA) was implemented to understand the cross-talk between various cell types. Further, differential gene expression analysis and enrichment analysis were carried out to identify unique molecular drivers associated with HCC and ICC. Our analysis identified T cells, hepatocytes, epithelial cells, and monocyte as the major cell types present in the tumor microenvironment. Among them, abundance of natural killer (NK) cells in HCC, epithelial cells, and hepatocytes in ICC was detected. CCA revealed key interaction between T cells to NK cells in HCC and smooth muscle cells to epithelial cells in the ICC. Additionally, SOX4 and DTHD1 are the top differentially expressed genes (DEGs) in HCC, while keratin and CCL4 are in ICC. Enrichment analysis of DEGs reveals major upregulated genes in HCC affect protein folding mechanism and in ICC alter pathways involved in cell adhesion. The findings suggest potential targets for the development of novel therapeutic strategies for the treatment of these two aggressive subtypes of LC.

E-Z Isomerization in Guanidine: Second-order Saddle Dynamics, Non-statisticality, and Time-frequency Analysis.

Our recent work on the E-Z isomerization reaction of guanidine using ab initio chemical dynamics simulations [Rashmi et al., Regul. Chaotic Dyn. 2021, 26, 119] emphasized the role of second-order saddle (SOS) in the isomerization reaction; however, we could not unequivocally establish the non-statistical nature of the dynamics followed in the reaction. In the present study, we performed thousands of on-the-fly trajectories using forces computed at the MNDO level to investigate the influence of second-order saddle in the E-Z isomerization reaction of guanidine and the role of intramolecular vibrational energy redistribution (IVR) on the reaction dynamics. The simulations reveal that while majority of the trajectories follow the traditional transition state pathways, 15 % of the trajectories follow the SOS path. The dynamics was found to be highly non-statistical with the survival probabilities of the reactants showing large deviations from those obtained within the RRKM assumptions. In addition, a detailed analysis of the dynamics using time-dependent frequencies and the frequency ratio spaces reveal the existence of multiple resonance junctions that indicate the existence of regular dynamics and long-lived quasi-periodic trajectories in the phase space associated with non-RRKM behavior.

Monochromatic visible lights modulate the timing of pre-adult developmental traits in Drosophila melanogaster.

Light exposure impacts several aspects of Drosophila development including the establishment of circadian rhythms, neuroendocrine regulation, life-history traits, etc. Introduction of artificial lights in the environment has caused almost all animals to develop ecological and physiological adaptations. White light which comprises different lights of differing wavelengths shortens the lifespan in fruit flies Drosophila melanogaster. The wavelength-specific effects of white light on Drosophila development remains poorly understood. In this study, we show that different wavelengths of white light differentially modulate Drosophila development in all its concomitant stages when maintained in a 12-h light: 12-h dark photoperiod. We observed that exposure to different monochromatic lights significantly alters larval behaviours such as feeding rate and phototaxis that influence pre-adult development. Larvae grown under shorter wavelengths of light experienced an altered feeding rate. Similarly, larvae were found to avoid shorter wavelengths of light but were highly attracted to the longer wavelengths of light. Most of the developmental processes were greatly accelerated under the green light regime while in other light regimes, the effects were highly varied. Interestingly, pre-adult survivorship remained unaltered across all light regimes but light exposure was found to show its impact on sex determination. Our study for the first time reveals how different wavelengths of white light modulate Drosophila development which in the future might help in developing non-invasive therapies and effective pest measures.

First report of Klebsiella Leaf Streak on Sorghum Caused by Klebsiella variicola in Haryana, India.

Sorghum (Sorghum bicolor [L.] Moench) is one of the top ten cereal crops in the world and is grown for fodder and seed purposes. During the fall of 2019 to 2022, a disease causing small to long streaks on leaves was observed in sorghum fields of Hisar (29° 9' 6.6996'' N, 75° 43' 16.0428'' E), Rohtak (28° 53' 43.8540'' N, 76° 36' 23.8068'' E) and Mohindergarh (28° 16' 6.0492'' N, 76° 9' 3.3552'' E) regions of Haryana between July and October. The reddish brown streaks were observed in the interveinal spaces of upper and lower leaves. The disease incidence reached 20-30% of plants in affected fields. The diseased leaf tissues were disinfected with 70% alcohol and placed in a tube with sterile water. After 30 minutes, 100 µl of the suspension was inoculated onto nutrient agar medium, incubated at 28 ± 2°C for three days, and a pure culture was obtained by restreaking on nutrient agar (Janse, 2005). The rod-shaped gram-negative bacterium with round, cream to white colonies was positive for methyl red, citrate utilization, urease activity, and glucose, lactose, sorbitol, rhamnose and sucrose fermentation tests. The genomic DNA of the bacterial suspension was extracted and 16S rDNA was amplified using universal 27F/1492R primers (Marchesi et al. 1998), resulting in tentative identification as Klebsiella sp. It was further confirmed with PCR amplification of Klebsiella specific primers (F:5'-CGCGTACTATACGCCATGAACGTA-3'; R:5'-ACCGTTGATCACTTCGGTCAGG-3') for gyrA gene (Brisse and Verhoef 2001). Discrete PCR amplicons of 1,500 (16S rDNA) and 300 bp (gyrA) were observed in a 1% (w/v) agarose gel. Forward and reverse DNA sequencing of both amplicons of the Hisar isolate (VMKV101) was carried out using a BDT v3.1 Cycle sequencing kit and consensus sequences were generated by using the program SeqMan Ultra (DNASTAR Lasergene). Sequences of the PCR products were deposited in GenBank with accession numbers MZ569433 (16S rDNA) and OP390080 (gyrA). The 16S rDNA sequence was 97.32% similar to K. variicola strain 13450 (CP026013; 1,450/1,490 bp) and the gyrA sequence had 99.66% similarity to K. variicola strain FH-1 (CP054254; 297/298 bp). A 16S RNA-based phylogenetic tree done by MEGA11 (Tamura et al. 2021) using the Maximum Likelihood method showed that strain VMKV101 clustered with K. variicola type strain F2R9. The complete bacterial genome (GCA025629215), sequenced by the Ion GeneStudio S5 system using Ion 530 chips (Thermo Fisher Scientific), was 99.03% identical by average nucleotide identity (ANI) to the type genome (CP045783) of Klebsiella variicola, with 87.8% genome coverage. For pathogenicity testing, a bacterial suspension (10 ml, 1×107 colony forming units/ml) was injected into the whole whorl after mechanical injury on 15-20 days old seedlings of the susceptible genotype HC-171, then plants were incubated at 35 ± 2°C, >80% relative humidity. Control plants were injected with sterile distilled water. Initial symptoms were observed on leaves of inoculated plants after 5 to 7 days as narrow, small longitudinal reddish brown streaks. As the disease progressed, the streaks on the leaf blade increased in number and size maintaining the reddish brown color. These streaks had slightly wavy margins and were surrounded by bright yellow halos. After 15 to 20 days, the streaks were 0.5 to 2.0 mm wide and 1.0 to 5.0 cm long, occasionally up to 10.0 cm long on both side of the leaves. Over time, neighboring streaks coalesced to form large necrotic areas. All inoculated plants exhibited identical symptoms. No symptoms were observed on control leaves. The reisolated bacterium from diseased sorghum leaves showed exactly the same morphological, biochemical and 16S RNA and gyrA molecular characteristics. To our knowledge, this is the first report of K. variicola causing a leaf streak disease on sorghum. Klebsiella species primarily cause diseases in humans and animals, but K. variicola has been found to incite banana soft rot (Fan et al. 2015) and K. aerogenes to cause stem rot in pearl millet (Malik et al. 2022). Differences of prevalence, spread and control between K. variicola and two other bacteria (Xanthomonas vasicola pv. holcicola causing Bacterial leaf streak; Paraburkholderia andropogonis causing Bacterial leaf stripe) causing leaf streak diseases on sorghum need to be determined. The identification of Klebsiella leaf streak disease lays the groundwork for future investigations into epidemiology and management of K. variicola on sorghum.

Restoring Angiotensin Type 2 Receptor Function Reverses PFOS-Induced Vascular Hyper-Reactivity and Hypertension in Pregnancy.

Perfluorooctane sulfonic acid (PFOS) exposure during pregnancy induces hypertension with decreased vasodilatory angiotensin type-2 receptor (AT2R) expression and impaired vascular reactivity and fetal weights. We hypothesized that AT2R activation restores the AT1R/AT2R balance and reverses gestational hypertension by improving vascular mechanisms. Pregnant Sprague-Dawley rats were exposed to PFOS through drinking water (50 µg/mL) from gestation day (GD) 4-20. Controls received drinking water with no detectable PFOS. Control and PFOS-exposed rats were treated with AT2R agonist Compound 21 (C21; 0.3 mg/kg/day, SC) from GD 15-20. In PFOS dams, blood pressure was higher, blood flow in the uterine artery was reduced, and C21 reversed these to control levels. C21 mitigated the heightened contraction response to Ang II and enhanced endothelium-dependent vasorelaxation in uterine arteries of PFOS dams. The observed vascular effects of C21 were correlated with reduced AT1R levels and increased AT2R and eNOS protein levels. C21 also increased plasma bradykinin production in PFOS dams and attenuated the fetoplacental growth restriction. These data suggest that C21 improves the PFOS-induced maternal vascular dysfunction and blood flow to the fetoplacental unit, providing preclinical evidence to support that AT2R activation may be an important target for preventing or treating PFOS-induced adverse maternal and fetal outcomes.

Rhizosphere Priestia species altered cowpea root transcriptome and enhanced growth under drought and nutrient deficiency.

MAIN CONCLUSION: Priestia species isolated from the cowpea rhizosphere altered the transcriptome of cowpea roots by colonization and enhanced nutrient uptake, antioxidant mechanisms, and photosynthesis, protecting cowpea from drought and nutrient deficiency. Cowpea is a significant grain legume crop primarily grown in sub-Saharan Africa, Asia, and South America. Drought and nutrient deficiency affect the growth and yield of cowpea. To address this challenge, we studied the phyto-beneficial effects of stress-tolerant rhizobacteria on the biomass yield of cowpea under water- and nutrient-deficit conditions. Among the bacteria isolated, two rhizobacillus genotypes, C8 (Priestia filamentosa; basonym: Bacillus filamentosus) and C29 (Priestia aryabhattai; basonym: Bacillus aryabhattai) were evaluated for the improvement of seed germination and growth of cowpea under stress. Our study revealed that C8 protected cowpea from stress by facilitating phosphorus and potassium uptake, protecting it from oxidative damage, reducing transpiration, and enhancing CO2 assimilation. A 17% increase in root biomass upon C8 inoculation was concomitant with the induction of stress tolerance genes in cowpea roots predominantly involved in growth and metabolic processes, cell wall organization, ion homeostasis, and cellular responses to phosphate starvation. Our results indicate a metabolic alteration in cowpea root triggered by P. filamentosa, leading to efficient nutrient reallocation in the host plant. We propose inoculation with P. filamentosa as an effective strategy for improving the yield of cowpea in low-input agriculture, where chemical fertilization and irrigation are less accessible to resource-poor farmers.

Advancement in Deep Learning Methods for Diagnosis and Prognosis of Cervical Cancer.

Cervical cancer is the leading cause of death in women, mainly in developing countries, including India. Recent advancements in technologies could allow for more rapid, cost-effective, and sensitive screening and treatment measures for cervical cancer. To this end, deep learning-based methods have received importance for classifying cervical cancer patients into different risk groups. Furthermore, deep learning models are now available to study the progression and treatment of cancerous cervical conditions. Undoubtedly, deep learning methods can enhance our knowledge toward a better understanding of cervical cancer progression. However, it is essential to thoroughly validate the deep learning-based models before they can be implicated in everyday clinical practice. This work reviews recent development in deep learning approaches employed in cervical cancer diagnosis and prognosis. Further, we provide an overview of recent methods and databases leveraging these new approaches for cervical cancer risk prediction and patient outcomes. Finally, we conclude the state-of-the-art approaches for future research opportunities in this domain.

The seesaw of diet restriction and lifespan: lessons from Drosophila studies.

Diet restriction (DR) studies undergo the implementation of reduced single or multiple component/s of the fly food without causing malnutrition. The question of how and why DR modifies the fate of lifespan in fruit flies Drosophila melanogaster has prompted us to emphasize by attending the control food composition first. Certain concentrations of DR food do not always confer an extended lifespan, rather it enables the flies to achieve their normal lifespan, which was probably reduced by the control food per se (having toxic effect caused due to the excess levels of dietary components). However, the current paradigm of DR studies has elicited its benefits and losses via trade-offs in the organismal traits and have highlighted the need for a common diet, but have not claimed the tested diets as balanced. So, the DR effect on lifespan and other fitness traits cannot be justified only based on varying control food across labs and hence, the approach of DR studies has to be revisited and a balanced diet has to be formulated. The current article discusses the need for a balanced diet, the traits to be considered before designing a diet, and certain problems in the existing synthetic medium. Therefore, based on the control food composition, the validity of lifespan extension conferred by these nutrient restricted diets need to be accounted for.

Design, synthesis and broad spectrum antibreast cancer activity of diarylindoles via induction of apoptosis in aggressive breast cancer cells.

Breast cancer is the second leading cause of cancer deaths in women with significant morbidity and mortality. Present study describes design, synthesis and detailed pharmacology of indole derivatives exhibiting remarkable broad spectrum antiproliferative activity against breast cancer cells. Detailed mechanistic evaluations confirmed induction of G0/G1 arrest, apoptosis induction, loss of mitochondrial integrity, enhanced ROS generation, autophagy, estrogen receptor ß-transactivation and increased tubulin polymerization. In in-vivo efficacy studies in rodent model, these indole derivatives induced significant regression in mice mammary tumour on 21 days daily oral dose. Moreover, compounds 19 and 23 were safe in Swiss albino mice in safety studies. These diarylindoles may further be optimized for better efficacy.

Zirconium-Based Metal Organic Frameworks for the Capture of Carbon Dioxide and Ethanol Vapour. A Comparative Study.

This paper reports on the comparison of three zirconium-based metal organic frameworks (MOFs) for the capture of carbon dioxide and ethanol vapour at ambient conditions. In terms of efficiency, two parameters were evaluated by experimental and modeling means, namely the nature of the ligands and the size of the cavities. We demonstrated that amongst three Zr-based MOFs, MIP-202 has the highest affinity for CO2 (-50 kJ·mol-1 at low coverage against around -20 kJ·mol-1 for MOF-801 and Muc Zr MOF), which could be related to the presence of amino functions borne by its aspartic acid ligands as well as the presence of extra-framework anions. On the other side, regardless of the ligand size, these three materials were able to adsorb similar amounts of carbon dioxide at 1 atm (between 2 and 2.5 µmol·m-2 at 298 K). These experimental findings were consistent with modeling studies, despite chemisorption effects, which could not be taken into consideration by classical Monte Carlo simulations. Ethanol adsorption confirmed these results, higher enthalpies being found at low coverage for the three materials because of stronger van der Waals interactions. Two distinct sorption processes were proposed in the case of MIP-202 to explain the shape of the enthalpic profiles.

Mechanoperovskites for Photovoltaic Applications: Preparation, Characterization, and Device Fabrication.

Hybrid organic-inorganic metal halide perovskites (MHPs) have emerged as excellent absorber materials for next generation solar cells owing to their simple solution-processed synthesis and high efficiency. This breakthrough in photovoltaics along with an accompanying impact in light-emitting applications prompted a renaissance of interest in the broad family of MHPs. Notably, the optoelectronic properties and the photovoltaic parameters of MHPs are highly sensitive to the adopted synthetic strategy. The preparation of MHPs has commonly relied on solution-based methods requiring elevated temperatures for homogeneity of reaction mixtures. While the solution-based approach is relatively versatile, it faces challenges such as limitations in compositional engineering of MHPs or their long-term storage among others. Therefore, there is a continuous great challenge to develop efficient synthetic strategies affording various high-quality MHP materials for numerous technological optoelectronic applications. In the past decade, mechanochemistry has appeared as a green alternative to traditional synthesis. This solid-state, re-emerging efficient synthetic methodology mediated by direct absorption of mechanical energy is growing explosively across organic and inorganic chemistry and materials science. In this Account, we describe our shared interest in the productive use of mechanical force in chemistry of MHPs, as well as assembly of the respective solar cell devices. We highlight the milestones achieved by our groups along with the seminal contributions by other groups. In particular, we demonstrate that mechanochemistry efficiently allows the formation of various phase pure hybrid lead and lead-free halide perovskite compositions (called hereafter "mechanoperovskites"). The progress in solvent-free solid-state synthesis is greatly enhanced by the integration of advanced methods of solid-state analysis like powder X-ray diffraction (pXRD), solid-state nuclear magnetic resonance (ss-NMR) and UV-vis spectroscopies, and we aim to illustrate this ongoing integration through appropriate examples. Furthermore, we show that thin films based on mechanoperovskites have the advantage of providing a higher degree of control of the stoichiometry and higher reproducibility, stability, and material phase purity. The impact of using powdered mechanoperovskite as a precursor for thin film formation on the electrochemical and photovoltaic properties of the solar cells is also discussed. Finally, our view of current challenges and future directions in this emerging interdisciplinary area of research is provided.

Synthesis and evaluation of substituted 8,8-dimethyl-8H-pyrano[2,3-f]chromen-2-one derivatives as vasorelaxing agents.

A series of substituted 8,8-dimethyl-8H-pyrano[2,3-f]chromen-2-ones (chromeno-coumarin hybrids) was synthesized from scopoletin (11) as vasorelaxing agents. The synthesized compounds 21a-f, 22, 23a-e and scopoletin (11) were evaluated for vasorelaxation in endothelium intact rat main mesenteric artery (MMA). Compounds 11, 21a, 21c-f and 22 showed significant vasorelaxation in precontracted MMA within the range of EC50 value 1.58-5.02 µM. These derivatives presented 29.40-70.89 fold increased sensitivity for experimental tissue compared to scopoletin (11), the parent molecule. Among others, 22 was found to be the most active compound which had EC50 1.58 µM with 70.89 fold increased sensitivity. The mechanistic evaluation of 22 showed that it exerted vasorelaxation through Ca2+-activated K+ (BKca) channel and the effect was endothelium-independent.

Elucidation of the role of guanidinium incorporation in single-crystalline MAPbI3 perovskite on ion migration and activation energy.

Ion migration plays a significant role in the overall stability and power conversion efficiency of perovskite solar cells (PSCs). This process was found to be influenced by the compositional engineering of the A-site cation in the perovskite crystal structure. However, the effect of partial A-site cation substitution in a methylammonium lead iodide (MAPbI3) perovskite on the ion migration process and its activation energy is not fully understood. Here we study the effect of a guanidinium (GUA) cation on the ion transport dynamics in the single crystalline GUAxMA1-xPbI3 perovskite composition using temperature-dependent electrochemical impedance spectroscopy (EIS). We find that the small substitution of MA with GUA decreases the activation energy for iodide ion migration in comparison to pristine MAPbI3. The presence of a large GUA cation in the 3D perovskite structure induces lattice enlargement, which perturbs the atomic interactions within the perovskite lattice. Consequently, the GUAxMA1-xPbI3 crystal exhibits a higher degree of hysteresis during current-voltage (J-V) measurements than the single-crystalline MAPbI3 counterpart. Our results provide the fundamental understanding of hysteresis, which is commonly observed in GUA-based PSCs and a general protocol for in-depth electrical characterization of perovskite single crystals.

Changes in the Electrical Characteristics of Perovskite Solar Cells with Aging Time.

The last decade has witnessed the impressive progress of perovskite solar cells (PSCs), with power conversion efficiency exceeding 25%. Nevertheless, the unsatisfactory device stability and current-voltage hysteresis normally observed with most PSCs under operational conditions are bottlenecks that hamper their further commercialization. Understanding the electrical characteristics of the device during the aging process is important for the design and development of effective strategies for the fabrication of stable PSCs. Herein, electrochemical impedance spectroscopical (IS) analyses are used to study the time-dependent electrical characteristics of PSC. We demonstrate that both the dark and light ideality factors are sensitive to aging time, indicating the dominant existence of trap-assisted recombination in the investigated device. By analyzing the capacitance versus frequency responses, we show that the low-frequency capacitance increases with increasing aging time due to the accumulation of charges or ions at the interfaces. These results are correlated with the observed hysteresis during the current-voltage measurement and provide an in-depth understanding of the degradation mechanism of PSCs with aging time.

Novel application of a calcium silicate‒based cement and platelet-rich fibrin in complex endodontic cases: a case series.

Three-dimensional sealing of root canals is essential for long-term endodontic success. It is sometimes difficult to achieve a fluid-tight seal in cases such as furcation defects, resorption lesions, open apices, and root fractures. Such cases require restorative materials that not only are biocompatible and well accepted by the surrounding periodontium but also will set in the wet oral environment without losing their properties. This case series describes management of an open apex, a furcal perforation, and a horizontal root fracture with a bioactive calcium silicate‒based cement (Biodentine) as root repair material. To prevent extrusion of the cement, platelet-rich fibrin was used as an external matrix. The patients were followed for 2-3 years, and the teeth demonstrated remarkable healing.