scholarly journals In-Situ Nano-Auger Probe of Chloride-Ions during CH3NH3PbI3-xClx Perovskite Formation

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1102
Author(s):  
Devthade Vidyasagar ◽  
Yong-Han Yun ◽  
Seunghak Shin ◽  
Jina Jung ◽  
Woosung Park ◽  
...  
Keyword(s):  
Perovskite Solar Cells ◽  
Microscopic Analysis ◽  
Auger Spectroscopy ◽  
Chloride Ions ◽  
High Power Conversion Efficiency ◽  
Electron Microscopic ◽  
Lower Temperature ◽  
High Flexibility ◽  
Increasing Temperature

Organo-halide perovskite solar cells (PSCs) have emerged as next-generation photovoltaics, owing to their high power-conversion efficiency (PCE), lower production cost, and high flexibility. ABX3-structured methylammonium lead triiodide (CH3NH3PbI3 or MAPbI3) perovskite is a widely studied light-absorbing material in PSCs. Interestingly, a small amount of chlorine incorporation into MAPbI3 increases charge carrier diffusion lengths (from 129 nm to 1069 nm), which enables planar structured PSCs with high PCEs. However, existence of chloride ions in the final perovskite film is still under debate. Contrastingly, few studies reported a negligible amount or absence of chloride ions in the final film, while others reported detection of chloride ions in the final film. Herein, we observed the microstructure and chlorine content of MAPbI3-xClx thin films with increasing temperature via an in-situ nano-Auger spectroscopy and in-situ scanning electron microscopic analysis. The relative precipitation of MAPbI3-xClx films occur at lower temperature and MAPbI3-xClx grains grow faster than those of MAPbI3 grains. Local concentrations of chlorine at intragrain and the vicinity of grain boundary were analyzed to understand the behavior and role of the chloride ions during the microstructural evolution of the MAPbI3-xClx films.

scholarly journals In-situ formed and low-temperature deposited Nb: TiO2 compact-mesoporous layer for hysteresis-less perovskite solar cells with high performance

2020 ◽  
Author(s):  
Miao Yu ◽  
Haoxuan Sun ◽  
Xiaona Huang ◽  
Yichao Yan ◽  
Wanli Zhang
Keyword(s):  
Solar Cells ◽  
Low Temperature ◽  
High Performance ◽  
High Efficiency ◽  
Perovskite Solar Cells ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
High Power Conversion Efficiency ◽  
Mesoporous Structures

Abstract Recently, reported perovskite solar cells (PSCs) with high power conversion efficiency (PCE) are mostly based on mesoporous structures containing mesoporous titanium oxide (TiO 2 ) which is the main factor to reduce the overall hysteresis. However, existing fabrication approaches for mesoporous TiO 2 generally require a high temperature (>450 °C) annealing process. Moreover, there is still plenty of scope for improvement in terms of increasing the electron conductivity and reducing the carrier recombination. Herein, a facile one-step, in situ and low-temperature method was developed to prepare an Nb:TiO 2 compact-mesoporous layer to serve as both a scaffold and an electron transport layer (ETL) in PSCs. The Nb:TiO 2 compact-mesoporous layer based PSCs exhibit suppressed hysteresis, which is attributed to the synergistic effect of the large interface surface area caused by nano-pin morphology on the surface and the improved carrier transportation caused by the presence of Nb. Such a high-quality compact-mesoporous layer allows the PSC achieve a remarkable PCE of 19.74%. This work promises an effective approach for creating hysteresis-less and high-efficiency PSCs based on compact-mesoporous structures with lower energy consumption and cost.

Biochemical and Structural Changes in Mitochondria and Other Cellular Components of Pea Cotyledons During Germination

1972 ◽  
Vol 50 (7) ◽  
pp. 725-737 ◽  
Author(s):  
T. Solomos ◽  
S. S. Malhotra ◽  
S. Prasad ◽  
S. K. Malhotra ◽  
Mary Spencer
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Gradient Centrifugation ◽  
Microscopic Analysis ◽  
Sucrose Density Gradient ◽  
Electron Microscopic ◽  
Sucrose Density Gradient Centrifugation ◽  
Cellular Components ◽  
Further Development

Integrated studies comprising biochemical and electron microscopic analysis suggested that the increase in respiratory activity of pea cotyledon mitochondria during germination results from further development of the original mitochondria present in dormant seeds. Electron microscopy of isolated mitochondria as well as mitochondria in situ has revealed that membranes are scarce in the mitochondria present in dormant seeds. Mitochondrial cristae become well developed during the initial stages of germination. Crude mitochondrial preparations from pea cotyledons were fractionated by sucrose density gradient centrifugation and analyzed through electron microscopy. These studies showed that, at all stages of germination, "peroxisome"-like structures were present in the fractions of higher sucrose densities than that containing mitochondria. Biochemical studies revealed that the activities of catalase (H2O2:H2O2 oxidoreductase, EC 1.11.1.6) and peroxidase (guaicol:H2O2 oxidoreductase, EC 1.11.1.7) were associated mainly with these fractions and their activities increased during germination.

Multi Objective Optimization of Wear Behaviour of In Situ AA8011-ZrB2 Metal Matrix Composites by Using Taguchi-Grey Analysis

2018 ◽  
Vol 928 ◽  
pp. 162-167 ◽  
Author(s):  
B.M. Muthamizh Selvan ◽  
V. Anandakrishnan ◽  
Muthukannan Duraiselvam ◽  
R. Venkatraman ◽  
S. Sathish
Keyword(s):  
Wear Rate ◽  
Microscopic Analysis ◽  
Casting Process ◽  
Stir Casting ◽  
Wear Behaviour ◽  
Dry Sliding Wear ◽  
Homogeneous Distribution ◽  
Tribological Behaviour ◽  
Electron Microscopic

Composite materials with aluminium alloy 8011 matrix and 0, 4 and 8 weight percentages of ZrB2reinforcements were synthesized by in-situ stir casting process. The presence and homogeneous distribution of the reinforcements were examined with X-ray diffraction analysis and scanning electron microscopic analysis. To investigate the effect of dry sliding wear parameters such as sliding distance, percentage reinforcement, load, sliding velocity and temperature on wear rate and co-efficient of friction, experiments were conducted using a pin on disc wear tester as per Taguchi’s orthogonal array design and the tribological behaviour of synthesized composites was investigated by statistical techniques. Significance and the influence of the parameters over the response were determined by analysis of variances and grey relational analysis was used to find the optimal combination of parameters to obtain minimum wear rate and co-efficient of friction.

scholarly journals Telomere Attachment, Meiotic Chromosome Condensation, Pairing, and Bouquet Stage Duration Are Modified in Spermatocytes Lacking Axial Elements

2004 ◽  
Vol 15 (2) ◽  
pp. 827-837 ◽  
Author(s):  
Bodo Liebe ◽  
Manfred Alsheimer ◽  
Christer Höög ◽  
Ricardo Benavente ◽  
Harry Scherthan
Keyword(s):  
Meiotic Chromosome ◽  
Microscopic Analysis ◽  
Chromosome Condensation ◽  
Chromosome 8 ◽  
Fine Tuning ◽  
Electron Microscopic ◽  
Homolog Pairing ◽  
Sister Chromatids ◽  
Bouquet Stage

During the extended prophase to the meiosis I division, chromosomes assemble axial elements (AE) along replicated sister chromatids whose ends attach to the inner nuclear membrane (NM) via a specialized conical thickening. Here, we show at the EM level that in Sycp3-/- spermatocyte chromosomes lack the AE and the conical end thickening, but still they attach their telomeres to the inner NM with an electron-dense plate that contains T2AG3 repeats. Immunofluorescence detected telomere proteins, SCP2, and the meiosis-specific cohesin STAG3 at the Sycp3-/- telomere. Bouquet stage spermatocytes were approximately threefold enriched, and the number of telomere but not centromere signals was reduced to the haploid in advanced Sycp3-/- spermatocytes, which indicates a special mode of homolog pairing at the mammalian telomere. Fluorescence in situ hybridization with mouse chromosome 8- and 12-specific subsatellite probes uncovered reduced levels of regional homolog pairing, whereas painting of chromosomes 13 revealed partial or complete juxtapositioning of homologs; however, condensation of Sycp3-/- bivalents was defective. Electron microscopic analysis of AE-deficient spermatocytes revealed that transverse filaments formed short structures reminiscent of the synaptonemal complex central region, which likely mediate stable homolog pairing. It appears that the AE is required for chromosome condensation, rapid exit from the bouquet stage, and fine-tuning of homolog pairing.

Cloning of a lymphatic peptide/histidine transporter

2001 ◽  
Vol 356 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Kazuko SAKATA ◽  
Toshihide YAMASHITA ◽  
Mitsuyo MAEDA ◽  
Yoshinori MORIYAMA ◽  
Shoichi SHIMADA ◽  
...  
Keyword(s):  
Northern Blot Analysis ◽  
Lymphatic System ◽  
Ectopic Expression ◽  
Microscopic Analysis ◽  
Peptide Transport ◽  
Electron Microscopic ◽  
Functional Relevance ◽  
Dependent Transport ◽  
The Brain

Although peptide transport across the plasma membrane has been characterized well in the kidney and the intestine, the functional relevance of this transport in other organs has not been addressed. Here we report the cloning of a cDNA for a novel peptide/histidine transporter found in the rat (rPHT2), whose mRNA is expressed mainly in the lymphatic system. rPHT2 encodes a protein of 582 amino acids and showed 49% identity with the brain PHT (PHT1) [Yamashita, Shimada, Guo, Sato, Kohmura, Hayakawa, Takagi and Tohyama (1997) J. Biol. Chem. 272, 10205–10211]. rPHT2 mRNA was abundant in lung, spleen and thymus, and detected faintly in brain, liver, adrenal gland and heart by Northern-blot analysis and reverse transcriptase PCR (RT-PCR). Intense signals for the gene were found in immunocytes using in situ hybridization. Ectopic expression of rPHT2 protein in HEK-293T cells and BHK cells was not found on the cell surface, but was found on the lysosomal membrane using light- and electron-microscopic analysis. Recombinant rPHT2 protein reconstituted into liposomes showed proton-dependent transport activity with histidine and histidyl-leucine. These findings suggest that rPHT2 is involved in the protein catabolic pathway in the lymphatic system.

scholarly journals The yeast MER2 gene is required for chromosome synapsis and the initiation of meiotic recombination.

Genetics ◽  
1995 ◽  
Vol 141 (1) ◽  
pp. 49-59
Author(s):  
B Rockmill ◽  
J A Engebrecht ◽  
H Scherthan ◽  
J Loidl ◽  
G S Roeder
Keyword(s):  
Meiotic Recombination ◽  
Microscopic Analysis ◽  
Primary Defect ◽  
Electron Microscopic ◽  
Strand Breaks ◽  
Meiotic Chromosomes ◽  
Chromosome Synapsis ◽  
Damage Repair

Abstract Mutation of the MER2 gene of Saccharomyces cerevisiae confers meiotic lethality. To gain insight into the function of the Mer2 protein, we have carried out a detailed characterization of the mer2 null mutant. Genetic analysis indicates that mer2 completely eliminates meiotic interchromosomal gene conversion and crossing over. In addition, mer2 abolishes intrachromosomal meiotic recombination, both in the ribosomal DNA array and in an artificial duplication. The results of a physical assay demonstrate that the mer2 mutation prevents the formation of meiosis-specific, double-strand breaks, indicating that the Mer2 protein acts at or before the initiation of meiotic recombination. Electron microscopic analysis reveals that the mer2 mutant makes axial elements, which are precursors to the synaptonemal complex, but homologous chromosomes fail to synapse. Fluorescence in situ hybridization of chromosome-specific DNA probes to spread meiotic chromosomes demonstrates that homolog alignment is also significantly reduced in the mer2 mutant. Although the MER2 gene is transcribed during vegetative growth, deletion or overexpression of the MER2 gene has no apparent effect on mitotic recombination or DNA damage repair. We suggest that the primary defect in the mer2 mutant is in the initiation of meiotic genetic exchange.

scholarly journals In-situ formed and low-temperature deposited Nb: TiO2 compact-mesoporous layer for hysteresis-less perovskite solar cells with high performance

2020 ◽  
Author(s):  
Miao Yu ◽  
Haoxuan Sun ◽  
Xiaona Huang ◽  
Yichao Yan ◽  
Wanli Zhang
Keyword(s):  
Solar Cells ◽  
Low Temperature ◽  
High Performance ◽  
High Efficiency ◽  
Perovskite Solar Cells ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
High Power Conversion Efficiency ◽  
Mesoporous Structures

Abstract Recently, reported perovskite solar cells (PSCs) with high power conversion efficiency (PCE) are mostly based on mesoporous structures containing mesoporous titanium oxide (TiO2 ) which is the main factor to reduce the overall hysteresis. However, existing fabrication approaches for mesoporous TiO2 generally require a high temperature annealing process. Moreover, there is still a long way to go for improvement in terms of increasing the electron conductivity and reducing the carrier recombination. Herein, a facile one-step, in situ and low-temperature method was developed to prepare an Nb: TiO2 compact-mesoporous layer to serve as both scaffold and electron transport layer (ETL) in PSCs. The Nb: TiO2 compact-mesoporous ETL based PSCs exhibit suppressed hysteresis, which is attributed to the synergistic effect of the large interface surface area caused by nano-pin morphology and the improved carrier transportation caused by Nb doping. Such a high-quality compact-mesoporous layer allows the PSC to achieve a remarkable PCE of 19.74%. This work promises an effective approach for creating hysteresis-less and high-efficiency PSCs based on compact-mesoporous structures with lower energy consumption and cost.

Preparatory Procedures for Electron Microscopic Analysis at the Molecular Level of Resolution

1978 ◽  
Vol 36 (3) ◽  
pp. 516-520
Author(s):  
F.J. Sjostrand
Keyword(s):  
Electron Microscope ◽  
Molecular Level ◽  
Microscopic Analysis ◽  
Resolving Power ◽  
Cellular Structures ◽  
Electron Microscopic ◽  
Systematic Analysis ◽  
Technical Developments ◽  
Thin Sectioning ◽  
Obvious Reason

In the 1940's and 1950's electron microscopy conferences were attended with everybody interested in learning about the latest technical developments for one very obvious reason. There was the electron microscope with its outstanding performance but nobody could make very much use of it because we were lacking proper techniques to prepare biological specimens. The development of the thin sectioning technique with its perfectioning in 1952 changed the situation and systematic analysis of the structure of cells could now be pursued. Since then electron microscopists have in general become satisfied with the level of resolution at which cellular structures can be analyzed when applying this technique. There has been little interest in trying to push the limit of resolution closer to that determined by the resolving power of the electron microscope.

Immunocytochemistry. A Review of Methodology for Electron Microscopic Applicaiton

1974 ◽  
Vol 32 ◽  
pp. 328-329
Author(s):  
Joseph E. Mazurkiewicz
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Ultrastructural Level ◽  
Electron Microscopic ◽  
Biological Interest ◽  
Investigative Approach ◽  
Immunologic Activity ◽  
Dense Label

Immunocytochemistry is a powerful investigative approach in which one of the most exacting examples of specificity, that of the reaction of an antibody with its antigen, isused to localize tissue and cell specific molecules in situ. Following the introduction of fluorescent labeled antibodies in T950, a large number of molecules of biological interest had been studied with light microscopy, especially antigens involved in the pathogenesis of some diseases. However, with advances in electron microscopy, newer methods were needed which could reveal these reactions at the ultrastructural level. An electron dense label that could be coupled to an antibody without the loss of immunologic activity was desired.

mRNA localization by Electron microscopic in situ hybridization

1991 ◽  
Vol 49 ◽  
pp. 430-431
Author(s):  
J. A. Pollock ◽  
M. Martone ◽  
T. Deerinck ◽  
M. H. Ellisman
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Nucleic Acids ◽  
Recombinant Dna ◽  
Light And Electron Microscopy ◽  
Electron Microscopic ◽  
High Voltage Electron Microscopy ◽  
Functional Sites ◽  
Voltage Electron

Localization of specific proteins in cells by both light and electron microscopy has been facilitate by the availability of antibodies that recognize unique features of these proteins. High resolution localization studies conducted over the last 25 years have allowed biologists to study the synthesis, translocation and ultimate functional sites for many important classes of proteins. Recently, recombinant DNA techniques in molecular biology have allowed the production of specific probes for localization of nucleic acids by “in situ” hybridization. The availability of these probes potentially opens a new set of questions to experimental investigation regarding the subcellular distribution of specific DNA's and RNA's. Nucleic acids have a much lower “copy number” per cell than a typical protein, ranging from one copy to perhaps several thousand. Therefore, sensitive, high resolution techniques are required. There are several reasons why Intermediate Voltage Electron Microscopy (IVEM) and High Voltage Electron Microscopy (HVEM) are most useful for localization of nucleic acids in situ.

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