Cis–trans isomerism, also known as geometric isomerism, describes certain arrangements of atoms within molecules. The prefixes "cis" and "trans" are from Latin: "this side of" and "the other side of", respectively. In the context of chemistry, cis indicates that the functional groups (substituents) are on the same side of some plane, while trans conveys that they are on opposing (transverse) sides. Cis–trans isomers are stereoisomers, that is, pairs of molecules which have the same formula but whose functional groups are in different orientations in three-dimensional space. Cis and trans isomers occur both in organic molecules and in inorganic coordination complexes. Cis and trans descriptors are not used for cases of conformational isomerism where the two geometric forms easily interconvert, such as most open-chain single-bonded structures; instead, the terms "syn" and "anti" are used.
In genetics, an enhancer is a short region of DNA that can be bound by proteins (activators) to increase the likelihood that transcription of a particular gene will occur. These proteins are usually referred to as transcription factors. Enhancers are cis-acting. They can be located up to 1 Mbp away from the gene, upstream or downstream from the start site. There are hundreds of thousands of enhancers in the human genome. They are found in both prokaryotes and eukaryotes.
In organic chemistry, the Knoevenagel condensation reaction is a type of chemical reaction named after German chemist Emil Knoevenagel. It is a modification of the aldol condensation.
Yanornis is an extinct genus of fish-eating Early Cretaceous birds. Two species have been described, both from Liaoning province, China: Yanornis martini, based on several fossils found in the 120-million-year-old Jiufotang Formation at Chaoyang, and Yanornis guozhangi, from the 124-million-year-old Yixian Formation.
Piceid is a stilbenoid glucoside and is a major resveratrol derivative in grape juices. It can be found in the bark of Picea sitchensis. It can also be isolated from Reynoutria japonica, the Japanese knotweed.
High-mobility group protein B2 also known as high-mobility group protein 2 (HMG-2) is a protein that in humans is encoded by the HMGB2 gene.
Cytokine-inducible SH2-containing protein is a protein that in humans is encoded by the CISH gene. CISH orthologs have been identified in most mammals with sequenced genomes. CISH controls T cell receptor (TCR) signaling, and variations of CISH with certain SNPs are associated with susceptibility to bacteremia, tuberculosis and malaria.
Suppressor of cytokine signaling 6 is a protein that in humans is encoded by the SOCS6 gene.
Pygostylia is a group of avialans which includes the Confuciusornithidae and all of the more advanced species, the Ornithothoraces.
Mitoferrin-1 (Mfrn1) is a 38 kDa protein that is encoded by the SLC25A37 gene in humans. It is a member of the Mitochondrial carrier (MC) Superfamily, however, its metal cargo makes it distinct from other members of this family. Mfrn1 plays a key role in mitochondrial iron homeostasis as an iron transporter, importing ferrous iron from the intermembrane space of the mitochondria to the mitochondrial matrix for the biosynthesis of heme groups and Fe-S clusters. This process is tightly regulated, given the redox potential of Mitoferrin's iron cargo. Mfrn1 is paralogous to Mitoferrin-2 (Mfrn2), a 39 kDa protein encoded by the SLC25A28 gene in humans. Mfrn1 is highly expressed in differentiating erythroid cells and in other tissues at low levels, while Mfrn2 is expressed ubiquitously in non-erythroid tissues.
The Jiufotang Formation is an Early Cretaceous geological formation in Chaoyang, Liaoning which has yielded fossils of feathered dinosaurs, primitive birds, pterosaurs, and other organisms. It is a member of the Jehol group. The exact age of the Jiufotang has been debated for years, with estimates ranging from the Late Jurassic to the Early Cretaceous. New uranium-lead dates reveal the formation is deposited in the Aptian stage of the Early Cretaceous. Fossils of Microraptor and Jeholornis are from the Jiufotang.
In chemistry, hyponitrite may refer to the anion N
2O2−
2 ([ON=NO]2−), or to any ionic compound that contains it. In organic chemistry, it may also refer to the group −O−N=N−O−, or any organic compound with the generic formula R1−O−N=N−O−R2, where R1 and R2 are organic groups. Such compounds can be viewed as salts and esters of respectively hyponitrous acid H
2N
2O
2 or HON=NOH.
Tetrafluoropropene, also called tetrafluoropropylene, has the following isomers:
The Tiaojishan Formation is a geological formation in Hebei and Liaoning, People's Republic of China, dating to the middle-late Jurassic period. It is known for its exceptionally preserved fossils, including those of plants, insects and vertebrates. It is made up mainly of pyroclastic rock interspersed with basic volcanic and sedimentary rocks. Previously, the Tiaojishan Formation was grouped together with the underlying Haifanggou Formation as a single "Lanqi Formation." The Tiaojishan Formation forms a key part of the Yanliao Biota assemblage, alongside the Haifanggou Formation.
Songlingornithidae is a family of basal euornitheans from the Early Cretaceous of China. All known specimens come from the Jiufotang Formation and the Yixian Formation, dating to the early Barremian and Aptian ages, 125–120 million years ago.
Hydrofluoroolefins (HFOs) are unsaturated organic compounds composed of hydrogen, fluorine and carbon. These organofluorine compounds are of interest as refrigerants. Unlike traditional hydrofluorocarbons (HFCs) and chlorofluorocarbons (CFCs), which are saturated, HFOs are olefins, otherwise known as alkenes.
trans-1,3,3,3-Tetrafluoropropene (HFO-1234ze(E), R-1234ze(E)) is a hydrofluoroolefin. It was developed as a "fourth generation" refrigerant to replace fluids such as R-134a, as a blowing agent for foam and aerosol applications, and in air horns and gas dusters. The use of R-134a is being phased out because of its high global warming potential (GWP). HFO-1234ze(E) itself has zero ozone-depletion potential (ODP=0), a very low global warming potential (GWP < 1 ), even lower than CO2, and it is classified by ANSI/ASHRAE as class A2L refrigerant (lower flammability and lower toxicity).
1,3,3,3-Tetrafluoropropene is a hydrofluoroolefin which has two isomers:
In molecular biology mir-425 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms.
15-Hydroxyeicosatetraenoic acid (also termed 15-HETE, 15(S)-HETE, and 15S-HETE) is an eicosanoid, i.e. a metabolite of arachidonic acid. Various cell types metabolize arachidonic acid to 15(S)-hydroperoxyeicosatetraenoic acid (15(S)-HpETE). This initial hydroperoxide product is extremely short-lived in cells: if not otherwise metabolized, it is rapidly reduced to 15(S)-HETE. Both of these metabolites, depending on the cell type which forms them, can be further metabolized to 15-oxo-eicosatetraenoic acid (15-oxo-ETE), 5(S),15(S)-dihydroxy-eicosatetraenoic acid (5(S),15(S)-diHETE), 5-oxo-15(S)-hydroxyeicosatetraenoic acid (5-oxo-15(S)-HETE), a subset of specialized pro-resolving mediators viz., the lipoxins, a class of pro-inflammatory mediators, the eoxins, and other products that have less well-defined activities and functions. Thus, 15(S)-HETE and 15(S)-HpETE, in addition to having intrinsic biological activities, are key precursors to numerous biologically active derivatives.
