scholarly journals Optical Properties and Stability of Bilayer Rubrene-Alq3 Films Fabricated by Vacuum Deposition

2018 ◽  
Vol 63 (4) ◽  
pp. 362 ◽  
Author(s):  
T. Gavrilko ◽  
V. Nechytaylo ◽  
L. Viduta ◽  
J. Baran
Keyword(s):  
Elevated Temperatures ◽  
Amorphous Film ◽  
Practical Application ◽  
Active Materials ◽  
Isomeric Transformation ◽  
Operational Lifetime ◽  
The Stability ◽  
First Time

We report on the optical and structural characterization of the two-component vacuum deposited (VD) rubrene (Rub)-Alq3 films. As is known, Rub-doped OLED active materials demonstrate both promising electroluminescence and transistor characteristics. However, in terms of operational lifetime, the Rub practical application in basic devices has a few draw-backs related to its chemical instability. Our main attention was focused on the role of the Alq3 coverage and the isomeric transformation of a Rub molecule on its chemical stability in these structures. By monitoring the evolution of PL emission in time, we found that the Rub degradation in Rub-Alq3 films is slower than that in vacuum-deposited Rub layers. These results demonstrate that the deposition of an Alq3 layer can be a way to enhance the stability of Rub to the photo-oxidation in optoelectronic devices. The Rub amorphous film crystallization at elevated temperatures in open air was observed for the first time.

scholarly journals The Double-Histone-Acetyltransferase Complex ATAC Is Essential for Mammalian Development

2008 ◽  
Vol 29 (5) ◽  
pp. 1176-1188 ◽  
Author(s):  
Sebastián Guelman ◽  
Kenji Kozuka ◽  
Yifan Mao ◽  
Victoria Pham ◽  
Mark J. Solloway ◽  
...  
Keyword(s):  
Cell Cycle Progression ◽  
Histone H4 ◽  
Mammalian Development ◽  
Histone Tails ◽  
Cycle Progression ◽  
Enzymatic Function ◽  
The Stability ◽  
First Time

ABSTRACT Acetylation of the histone tails, catalyzed by histone acetyltransferases (HATs), is a well-studied process that contributes to transcriptionally active chromatin states. Here we report the characterization of a novel mammalian HAT complex, which contains the two acetyltransferases GCN5 and ATAC2 as well as other proteins linked to chromatin metabolism. This multisubunit complex has a similar but distinct subunit composition to that of the Drosophila ADA2A-containing complex (ATAC). Recombinant ATAC2 has a weak HAT activity directed to histone H4. Moreover, depletion of ATAC2 results in the disassembly of the complex, indicating that ATAC2 not only carries out an enzymatic function but also plays an architectural role in the stability of mammalian ATAC. By targeted disruption of the Atac2 locus in mice, we demonstrate for the first time the essential role of the ATAC complex in mammalian development, histone acetylation, cell cycle progression, and prevention of apoptosis during embryogenesis.

scholarly journals Mass bleaching of soft coral, Sarcophyton spp. in Thailand and the role of temperature and salinity stress

2009 ◽  
Vol 66 (7) ◽  
pp. 1515-1519 ◽  
Author(s):  
Suchana Chavanich ◽  
Voranop Viyakarn ◽  
Thepsuda Loyjiw ◽  
Priyapat Pattaratamrong ◽  
Anchalee Chankong
Keyword(s):  
Salinity Stress ◽  
Soft Coral ◽  
Elevated Temperatures ◽  
Gulf Of Thailand ◽  
Field Observations ◽  
Experimental Trial ◽  
First Time ◽  
Upper Gulf Of Thailand ◽  
Mass Bleaching

Abstract Chavanich, S., Viyakarn, V., Loyjiw, T., Pattaratamrong, P., and Chankong, A. 2009. Mass bleaching of soft coral, Sarcophyton spp. in Thailand and the role of temperature and salinity stress. – ICES Journal of Marine Science, 66: 1515–1519. From June to October 2006 and 2007, mass bleaching of the soft coral, Sarcophyton spp., occurred for the first time in the upper Gulf of Thailand. Approximately 90% of the populations experienced extensive bleaching, and almost 95% of colonies were affected. Field observations also revealed that fragmentation of Sarcophyton spp. set in 1 month after the onset of bleaching. Some colonies started to recover to some extent by the end of July, with 95% of the population of Sarcophyton spp. recovering by October. Both acute and chronic trials were conducted to determine whether temperature and/or salinity triggered bleaching. In the acute tests, Sarcophyton spp. at 40°C and salinity 20 psu were completely bleached, and death occurred after 57 and 204 h, respectively. However, the colonies at 40 psu could survive through the experimental trial. In the chronic tests, Sarcophyton spp. died when exposed to 34°C, whereas complete bleaching and mortality of Sarcophyton spp. occurred at salinities of 10 and 49 psu. We conclude that elevated temperatures had a greater effect on the bleaching of Sarcophyton spp. than did salinity.

scholarly journals Molecular analysis of the microflora in chronic venous leg ulceration

2003 ◽  
Vol 52 (4) ◽  
pp. 365-369 ◽  
Author(s):  
K.E. Hill ◽  
C.E. Davies ◽  
M.J. Wilson ◽  
P. Stephens ◽  
K.G. Harding ◽  
...  
Keyword(s):  
Individual Species ◽  
Venous Leg Ulcer ◽  
Bacterial Populations ◽  
Cultural Methods ◽  
Rdna Sequences ◽  
Oral Microflora ◽  
16S Rdna Sequences ◽  
First Time

There is growing evidence to suggest that the resident microflora of chronic venous leg ulcers impairs cellular wound-healing responses, thereby playing an important role in maintaining the non-healing phenotype of many of these wounds. The significance of individual species of bacteria will remain unclear until it is possible to characterize fully the microflora of such lesions. The limitations and biases of culture-based microbiology are being realized and the subsequent application of molecular methods is revealing greater diversity within mixed bacterial populations than that demonstrated by culture alone. To date, this approach has been limited to a small number of systems, including the oral microflora. Here, for the first time, the comprehensive characterization of the microflora present in the tissue of a chronic venous leg ulcer is described by the comparison of 16S rDNA sequences amplified directly from the wound tissue with sequences obtained from bacteria that were isolated by culture. The molecular approach demonstrated significantly greater bacterial diversity than that revealed by culture. Furthermore, sequences were retrieved that may possibly represent novel species of bacteria. It is only by the comprehensive analysis of the wound microflora by both molecular and cultural methods that it will be possible to further our understanding of the role of bacteria in this important condition.

Cloning and characterization of LOS1, a Saccharomyces cerevisiae gene that affects tRNA splicing

1987 ◽  
Vol 7 (3) ◽  
pp. 1208-1216 ◽  
Author(s):  
D J Hurt ◽  
S S Wang ◽  
Y H Lin ◽  
A K Hopper
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Elevated Temperatures ◽  
Trna Gene ◽  
Single Copy ◽  
Molecular Study ◽  
Trna Splicing ◽  
Intervening Sequences ◽  
Copy Gene

Saccharomyces cerevisiae strains carrying los1-1 mutations are defective in tRNA processing; at 37 degrees C, such strains accumulate tRNA precursors which have mature 5' and 3' ends but contain intervening sequences. Strains bearing los1-1 and an intron-containing ochre-suppressing tRNA gene, SUP4(0), also fail to suppress the ochre mutations ade2-1(0) and can1-100(0) at 34 degrees C. To understand the role of the LOS1 product in tRNA splicing, we initiated a molecular study of the LOS1 gene. Two plasmids, YEpLOS1 and YCpLOS1, that complement the los1-1 phenotype were isolated from the YEp24 and YCp50 libraries, respectively. YEpLOS1 and YCpLOS1 had overlapping restriction maps, indicating that the DNA in the overlapping segment could complement los1-1 when present in multiple or single copy. Integration of plasmid DNA at the LOS1 locus confirmed that these clones contained authentic LOS1 sequences. Southern analyses showed that LOS1 is a single copy gene. The locations of the LOS1 gene within YEpLOS1 and YCpLOS1 were determined by deletion and gamma-delta mapping. Two genomic disruptions of the LOS1 gene were constructed, i.e., an insertion of a 1.2-kilobase fragment carrying the yeast URA3 gene, los1::URA3, and a 2.4-kilobase deletion from the LOS1 gene, los1-delta V. Disruption or deletion of most of the LOS1 gene was not lethal; cells carrying the disrupted los1 alleles were viable and had phenotypes similar to those of cells carrying the los1-1 allele. Thus, it appears that the los1 gene product expedites tRNA splicing at elevated temperatures but is not essential for this process.

scholarly journals Immobilization of Eversa Lipase on Octyl Agarose Beads and Preliminary Characterization of Stability and Activity Features

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 511 ◽  
Author(s):  
Sara Arana-Peña ◽  
Yuliya Lokha ◽  
Roberto Fernández-Lafuente
Keyword(s):  
Immobilized Enzyme ◽  
Biodiesel Production ◽  
Free Form ◽  
Enzyme Specificity ◽  
Agarose Beads ◽  
The Stability ◽  
Isoform B ◽  
First Time ◽  
Commercial Lipase

Eversa is an enzyme recently launched by Novozymes to be used in a free form as biocatalyst in biodiesel production. This paper shows for first time the immobilization of Eversa (a commercial lipase) on octyl and aminated agarose beads and the comparison of the enzyme properties to those of the most used lipase, the isoform B from Candida antarctica (CALB) immobilized on octyl agarose beads. Immobilization on octyl and aminated supports of Eversa has not had a significant effect on enzyme activity versus p-nitrophenyl butyrate (pNPB) under standard conditions (pH 7), but immobilization on octyl agarose beads greatly enhanced the stability of the enzyme under all studied conditions, much more than immobilization on aminated support. Octyl-Eversa was much more stable than octyl-CALB at pH 9, but it was less stable at pH 5. In the presence of 90% acetonitrile or dioxane, octyl-Eversa maintained the activity (even increased the activity) after 45 days of incubation in a similar way to octyl-CALB, but in 90% of methanol, results are much worse, and octyl-CALB became much more stable than Eversa. Coating with PEI has not a clear effect on octyl-Eversa stability, although it affected enzyme specificity and activity response to the changes in the pH. Eversa immobilized octyl supports was more active than CALB versus triacetin or pNPB, but much less active versus methyl mandelate esters. On the other hand, Eversa specificity and response to changes in the medium were greatly modulated by the immobilization protocol or by the coating of the immobilized enzyme with PEI. Thus, Eversa may be a promising biocatalyst for many processes different to the biodiesel production and its properties may be greatly improved following a suitable immobilization protocol, and in some cases is more stable and active than CALB.

Phonons in deformable microporous crystalline solids

2019 ◽  
Vol 234 (7-8) ◽  
pp. 513-527 ◽  
Author(s):  
Bogdan Kuchta ◽  
Filip Formalik ◽  
Justyna Rogacka ◽  
Alexander V. Neimark ◽  
Lucyna Firlej
Keyword(s):  
Periodic Structures ◽  
Structural Transformations ◽  
Crystalline Solids ◽  
Predictive Tool ◽  
Crystalline Materials ◽  
Numerical Tools ◽  
Collective Vibrations ◽  
First Time

Abstract Phonons are quantum elastic excitations of crystalline solids. Classically, they correspond to the collective vibrations of atoms in ordered periodic structures. They determine the thermodynamic properties of solids and their stability in the case of structural transformations. Here we review for the first time the existing examples of the phonon analysis of adsorption-induced transformations occurring in microporous crystalline materials. We discuss the role of phonons in determining the mechanism of the deformations. We point out that phonon-based methodology may be used as a predictive tool in characterization of flexible microporous structures; therefore, relevant numerical tools must be developed.

scholarly journals A small mitochondrial protein present in myzozoans is essential for malaria transmission

Open Biology ◽  
2016 ◽  
Vol 6 (4) ◽  
pp. 160034 ◽  
Author(s):  
Dennis Klug ◽  
Gunnar R. Mair ◽  
Friedrich Frischknecht ◽  
Ross G. Douglas
Keyword(s):  
Drug Targets ◽  
Mitochondrial Protein ◽  
Sister Group ◽  
Developmental Defect ◽  
Mitochondrial Mass ◽  
First Time ◽  
Potential Drug Targets ◽  
Identification And Characterization

Myzozoans (which include dinoflagellates, chromerids and apicomplexans) display notable divergence from their ciliate sister group, including a reduced mitochondrial genome and divergent metabolic processes. The factors contributing to these divergent processes are still poorly understood and could serve as potential drug targets in disease-causing protists. Here, we report the identification and characterization of a small mitochondrial protein from the rodent-infecting apicomplexan parasite Plasmodium berghei that is essential for development in its mosquito host. Parasites lacking the gene mitochondrial protein ookinete developmental defect ( mpodd ) showed malformed parasites that were unable to transmit to mosquitoes. Knockout parasites displayed reduced mitochondrial mass without affecting organelle integrity, indicating no role of the protein in mitochondrial biogenesis or morphology maintenance but a likely role in mitochondrial import or metabolism. Using genetic complementation experiments, we identified a previously unrecognized Plasmodium falciparum homologue that can rescue the mpodd(−) phenotype, thereby showing that the gene is functionally conserved. As far as can be detected, mpodd is found in myzozoans, has homologues in the phylum Apicomplexa and appears to have arisen in free-living dinoflagellates. This suggests that the MPODD protein has a conserved mitochondrial role that is important for myzozoans. While previous studies identified a number of essential proteins which are generally highly conserved evolutionarily, our study identifies, for the first time, a non-canonical protein fulfilling a crucial function in the mitochondrion during parasite transmission.

scholarly journals Isolation and Characterization of Cryptococcus neoformans Spores Reveal a Critical Role for Capsule Biosynthesis Genes in Spore Biogenesis

2009 ◽  
Vol 8 (4) ◽  
pp. 595-605 ◽  
Author(s):  
Michael R. Botts ◽  
Steven S. Giles ◽  
Marcellene A. Gates ◽  
Thomas R. Kozel ◽  
Christina M. Hull
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Pathogens ◽  
Critical Role ◽  
Spore Formation ◽  
Yeast Cells ◽  
Isolation And Characterization ◽  
Specific Configuration ◽  
First Time

ABSTRACT Spores are essential particles for the survival of many organisms, both prokaryotic and eukaryotic. Among the eukaryotes, fungi have developed spores with superior resistance and dispersal properties. For the human fungal pathogens, however, relatively little is known about the role that spores play in dispersal and infection. Here we present the purification and characterization of spores from the environmental fungus Cryptococcus neoformans. For the first time, we purified spores to homogeneity and assessed their morphological, stress resistance, and surface properties. We found that spores are morphologically distinct from yeast cells and are covered with a thick spore coat. Spores are also more resistant to environmental stresses than yeast cells and display a spore-specific configuration of polysaccharides on their surfaces. Surprisingly, we found that the surface of the spore reacts with antibodies to the polysaccharide glucuronoxylomannan, the most abundant component of the polysaccharide capsule required for C. neoformans virulence. We explored the role of capsule polysaccharide in spore development by assessing spore formation in a series of acapsular strains and determined that capsule biosynthesis genes are required for proper sexual development and normal spore formation. Our findings suggest that C. neoformans spores may have an adapted cell surface that facilitates persistence in harsh environments and ultimately allows them to infect mammalian hosts.

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