(n.) A gaseous element, colorless, tasteless, and odorless, the lightest known substance, being fourteen and a half times lighter than air (hence its use in filling balloons), and over eleven thousand times lighter than water. It is very abundant, being an ingredient of water and of many other substances, especially those of animal or vegetable origin. It may by produced in many ways, but is chiefly obtained by the action of acids (as sulphuric) on metals, as zinc, iron, etc. It is very inflammable, and is an ingredient of coal gas and water gas. It is standard of chemical equivalents or combining weights, and also of valence, being the typical monad. Symbol H. Atomic weight 1.
Example Sentences:
(1) The hypothesis that proteins are critical targets in free radical mediated cytolysis was tested using U937 mononuclear phagocytes as targets and iron together with hydrogen peroxide to generate radicals.
(2) It has been conformed that catalase from bovine liver eliminates only the pro R hydrogen atom from ethanol.
(3) We investigated the possible contribution made by oropharyngeal microfloral fermentation of ingested carbohydrate to the generation of the early, transient exhaled breath hydrogen rise seen after carbohydrate ingestion.
(4) Hydrogen isotope effects on these mutants indicate that MotA catalyzes proton transfer.
(5) Excessive accumulation of hydrogen ions in the brain may play a pivotal role in initiating the necrosis seen in infarction and following hyperglycemic augmentation of ischemic brain damage.
(6) Studies were conducted in isolated, buffer-perfused rat lungs to determine if prostaglandin (PG) E1 attenuated pulmonary edema provoked by hydrogen peroxide (H2O2).
(7) All N and O atoms except N(3) and O(4') participate in a three-dimensional hydrogen-bonding system.
(8) Both adiphenine.HCl and proadifen.HCl form more stable complexes, suggesting that hydrogen bonding to the carbonyl oxygen by the hydroxyl-group on the rim of the CD ring could be an important contributor to the complexation.
(9) Control mutant S38N has stability essentially the same as that of wild-type lysozyme but hydrogen bonding similar to that of the stabilizing mutant S38D.
(10) High intensity ultrasound also enhances the heterogeneous catalysis of alkene hydrogenation by Ni powders.
(11) An atmosphere of hydrogen eliminates this inhibition in the hydrogenase-containing T. foetus but not in E. invadens which lacks the enzyme.
(12) Vanadate-dependent oxidation of either pyridine nucleotide was inhibited by the addition of either superoxide dismutase or catalase, indicating that both superoxide and hydrogen peroxide may be intermediates in the process.
(13) Our findings suggest that (a) the inclusion of a liquid meal provides a reproducible method of measuring orocaecal transit using the lactulose hydrogen breath test, (b) rapid small bowel transit in thyrotoxicosis may be one factor in the diarrhoea which is a feature of the disease and (c) if altered gut transit is the cause of sluggish bowel habit in hypothyroidism, delay in the colon, and not small bowel, is likely to be responsible.
(14) Stepwise hydrogenation of metal tetradehydrocorrin salts (10 double bonds) yields a series of macrocycles containing 9, 8, 7, 6 and 5 double bonds and conditions necessary to obtain corrins have been established.
(15) For dipeptides containing the amino terminal residues glycine, alanine and phenylalanine, abstraction of the hydrogen from the carbon adjacent to the peptide nitrogen was the major process leading to the spin-adducts.
(16) (7) The first-order radical transformation rates are independent of the (initial) concentration of N3 or peptide and unaffected by urea (as a modifier of hydrogen bond structures).
(17) Intermolecular contacts occur in both oligomers in the minor groove: in the B form through twisted guanine-guanine hydrogen bonding, and in the Z form through base-base stacking and the water network.
(18) Equilibrium-partitioning measurements indicate that the relative affinities of different probes for PC-rich vesicles, in competition with HODMA or DOTAP vesicles, increase with increasing hydrogen-bonding capacity of the probe headgroup in the order PC less than N,N-dimethyl PE less than N-methyl PE less than PE approximately phosphatidyl-2-amino-1-propanol.
(19) When tissue metabolism was irreversibly inhibited by exposure to formaldehyde, hydrogen ion concentration and pCO2 were significantly decreased in the mucosal side of the chamber compared with the viable gall bladder.
(20) Based on the refined atomic coordinates of the tRNAphe in the orthorhombic crystal, on the recent advances in the distance dependence of the ring-current magnetic field effects and on the adopted values for the isolated hydrogen-bonded NH resonances, a computed spectrum consisting of 23 protons was constructed.
Pentad
Definition:
(n.) Any element, atom, or radical, having a valence of five, or which can be combined with, substituted for, or compared with, five atoms of hydrogen or other monad; as, nitrogen is a pentad in the ammonium compounds.
(a.) Having the valence of a pentad.
Example Sentences:
(1) Thrombotic thrombocytopenic purpura (TTP) is characterized by the pentad of fever, thrombocytopenia, microangiopathic hemolytic anemia, fluctuating neurologic symptoms, and renal dysfunction.
(2) This case supports the associational of thoracoabdominal ectopia cordis (Cantrell's pentad) with chromosomal errors, specifically trisomy 18.
(3) Of the 41 botulinal toxin-positive persons, 38 (93%) had at least three of the commonly recognized pentad of signs or symptoms--nausea and vomiting, dysphagia, diplopia, dilated and fixed pupils, or dry mouth and throat--and 20 (49%) required respiratory assistance.
(4) Review of the reported literature of the Pentalogy of Cantrell and various combinations of the anomalies within the spectrum of this pentad suggests that the PC defines a specific midline ventral developmental field.
(5) There was an increase in the numbers of 'bare' T-tubules and an increased occurrence of diadic, pentadic and heptadic junctions between the membranes of the T-tubules and terminal cisternae.
(6) It is characterized by a pentad of clinical findings: fever, neurological abnormalities, renal dysfunction, microangiopathic hemolytic anemia and thrombocytopenia.
(7) Clinical signs and symptoms of nausea and vomiting, dysphagia, diplopia, dilated pupils, and dry throat occurred with great frequency, forming a diagnostic pentad.
(8) Other clinical features were present inconsistently, and only 34% of "TTP" episodes involved the classic pentad of hemolytic anemia, thrombocytopenia, neurologic disorders, noninfectious fever, and renal impairment.
(9) Common bile duct lithiasis was responsible in 80% of cases presenting with Reynolds' pentad and in 66% of postoperative mortality.
(10) The presence of renal impairment, occurring as frequently as any of the pentad of features that characterize the syndrome, has important implications for the prognosis and long term management of these patients.
(11) By using more specific criteria than the classical clinical pentad, the diagnosis of thrombotic thrombocytopenic purpura during pregnancy can be made with greater accuracy.
(12) It is characterized by a pentad of clinical findings, including microangiopathic hemolytic anemia, thrombocytopenic purpura, neurologic and renal abnormalities, and fever.
(13) Information from out patients with thrombotic thrombocytopenic purpura implicates respiratory dysfunction as a component of this disease as well as the classically described pentad.
(14) Nuclear chain fibers, in contrast, possess an unusually well-developed SR and T system and a variety of multiple junctional couplings (dyads, triads, quatrads, pentads, septads).
(15) 23% of the 17 patients with pus in the bile duct showed Reynolds' pentad, which was observed in 10% of patients with nonsuppurative acute cholangitis.
(16) During anaphase I the pentad sex chromosomes lie freely between the two sister cells.
(17) It is of prognostic significance, and should be considered as important as the clinical findings of Reynold's pentad.
(18) Thrombotic thrombocytopenic purpura (TTP) is a rare disorder of unknown etiology, clinically characterized by a diagnostic pentad (thrombocytopenia, microangiopathic hemolytic anemia, neurologic signs and symptoms, fever and renal damage).
(19) Diagnosis of TTP is usually made on the basis of the pentad of anemia, thrombocytopenia, renal disease, neurologic abnormalities, and fever.
(20) The tetrade "REST syndrome" becomes in these cases the pentade "CREST syndrome".