30,802 research outputs found
Studies of novel nitro-substituted nitrogen heterocyclic compounds
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The novel candidate high energy insensitive explosive; 2,5-diamino-3,6-dinitropyrazine (ANPZ-i) has been prepared in acceptable overall yield. ANPZ-i was synthesised by the nitration of 2,5-diethoxypyrazine using nitronium tetrafluoroborate (NO2+BF4-) in sulfolane and the subsequent amination of 2,5-diethoxy-3,6-dinitropyrazine, under autoclave conditions. Oxidation studies towards the dioxide derivative of ANPZ-i, 2,5-diamino-3,6-dinitropyrazine-1,4-dioxide (PZDO), were unsuccessful. The synthesis of existing high explosives; 2,6-diamino-3,5-dintropyrazine (ANPZ) and 2,6-diamino-3,5-dinitropyrazine-1-oxide (PZO) has been scaled up to produce approximately 25 g batches of material. A number of novel nitrations using NO2+BF4- have been carried out on a range of chloro-, methyl- and hydroxy-functionalised quinoxalines and quinazolines. A range of novel functionalisations have also been carried out on the platform molecule; 2,4-diamino-6,8-dinitroquinazoline giving rise to 2,4-diamino-6,8-dinitroquinazoline-1,3-dioxide (di-N-oxidation product), 2,4,7-triamino-6,8-dinitroquinazoline (monoamination product) and 2,4,6,8-tetra-aminoquinazoline (dihydrogenation product).
Detonics molecular modelling was carried out on the following target molecules: 2,5-diamino-3,6-dinitropyrazine-1,4-dioxide (PZDO), 2,5,8-triamino-3,6,7-trinitroquinoxaline-1-oxide and 2,5,7-triamino-4,6,8-trinitroquinazoline-1-oxide. The detonation velocity of the new explosive molecule; 2,5-diamino-3,6-dinitropyrazine (ANPZ-i) was calculated and it was found to be a similar value to that obtained experimentally for the existing high explosive RDX. Calculation by molecular modelling of the steric energies of ANPZ, PZO, ANPZ-i and PZDO gave a quantitative assessment of the difficulty in oxidising ANPZ-i to give PZDO. Extensive analysis of carbon-13 NMR spectroscopy shift values was carried out for approximately twenty nitrogen heterocyclic compounds. Comparison of shift values indicated consistency in the interpretations.
On-line literature searches have shown that the following compounds prepared in this project are new: 2,3,6-trichloro-5-nitroquinoxaline, 2,3-dimethoxy-6,7-dinitroquinoxaline, 2,3,6-trichloroquinoxaline-1-oxide, 2,4-diamino-6,8-dinitroquinazoline-1,3-dioxide, 2,4,7-triamino-6,8-dinitroquinazoline and 2,5-diamino-3,6-dinitropyrazine (ANPZ-i). Furthermore, new synthetic routes have been used in the preparation of the following compounds: 2,3-dichloro-5-nitroquinoxaline, 2,3,6,7-tetrachloro-5-nitroquinoxaline, 2-hydroxy-6-nitroquinoxaline, 2-hydroxy-3-methyl-6-nitroquinoxaline and 2,5-diethoxy-3,6-dinitropyrazine
William Tarn, Hellenistic Civilisation. Third Edition revised by the Author and G. T. Griffith
No full textNachtergael Georges. William Tarn, Hellenistic Civilisation. Third Edition revised by the Author and G. T. Griffith. In: L'antiquité classique, Tome 44, fasc. 2, 1975. p. 782
William Tarn, Hellenistic Civilisation. Third Edition revised by the Author and G. T. Griffith
No full textNachtergael Georges. William Tarn, Hellenistic Civilisation. Third Edition revised by the Author and G. T. Griffith. In: L'antiquité classique, Tome 44, fasc. 2, 1975. p. 782
Selective tumor cell death induced by irradiated riboflavin through recognizing DNA G-T mismatch
No full textRiboflavin (vitamin B2) has been thought to be a promising antitumoral agent in photodynamic therapy, though the further application of the method was limited by the unclear molecular mechanism. Our work reveals that riboflavin was able to recognize G-T mismatch specifically and induce singlestrand breaks in duplex DNA targets efficiently under irradiation. In the presence of riboflavin, the photo-irradiation could induce the death of tumor cells that are defective in mismatch repair system selectively, highlighting the G-T mismatch as potential drug target for tumor cells. Moreover, riboflavin is a promising leading compound for further drug design due to its inherent specific recognition of the G-T mismatch
f(G,T) and its Cosmological Implications
No full textA coupled formulation of the Gauss-Bonnet invariant term G and the
energy momentum trace T term provide a modified f(G,T) gravity,
has been analyzed in this study. The functional form for the
f(G,T) gravity has been taken as f(G,T)=αT+ βGThe presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Identification of Immune Gene Signature Associated with T Cells and Natural Killer Cells in Type 1 Diabetes [Corrigendum]
No full textWang N, Wang G, Feng X, Yang T. Diabetes Metab Syndr Obes. 2024;17:2983—2996.
The authors have advised the affiliation callouts in the author list on page 2983 are incorrect. The correct author callouts should read as follows:
Na Wang1, Guofeng Wang1,2, Xiuli Feng1, Teng Yang
Elaboration on Kwapien's theorem: Representing bounded mean zero functions f as coboundary f = g ◦ T − g
No full textIn [8] Kwapien proved that every mean zero function f ∈ L∞[0, 1] we can write as f = g ◦ T − g for some g ∈ L∞[0, 1] and some measure preserving transformation T of [0, 1]. However, as was discovered in [4] there is a gap in the proof for the case that f is not continuous. The aim of this bachelor thesis is filling in that gap in the proof. We first extend Kwapien’s proof for continuous functions to certain other measure spaces. Thereafter, we use the method of proof suggested by Kwapien, to proof the theorem for mean zero function f ∈ L∞[0, 1] for which λ(f−1({x})) = 0 for all x ∈ R. Using this result we then proof that every mean zero function f ∈ L∞[0, 1] can be written as a sum f =(g1 ◦ T1 − g1) + (g2 ◦ T2 − g2) where g1, g2 ∈ L∞[0, 1] and where T1, T2 are measure preserving transformations of [0, 1]. We finish this thesis with an application of Kwapien’s theorem in the study to singular traces Applied Mathematic
Lost in Translation. About the Castilian Gloss on Giles of Rome’s De regimine principum
No full textThe paper shows how deep are the changes that Giles of Rome's de regimine principum undergoes in the so-called Castilian Gloss. the traditional attibution to the Franciscan friar Juan Garcia de Castrojeriz has been challenged. The paper claims, however, on internal evidence, that the author must have been a Franciscan friar. The book is edited by G. Briguglia and T. Ricklin
Perfect transmission through disordered media
No full textThis is the author accepted manuscript. The final version is available from American Physical Society via the DOI in this record.The transmission of a wave through a randomly chosen `pile of plates' typically decreases expo-
nentially with the number of plates, a phenomenon closely related to Anderson localisation. In ap-
parent contradiction we construct disordered planar permittivity pro les which are complex-valued
(i.e. have reactive and dissipative properties) that appear to vary randomly with position, yet are
one-way re
ectionless for all angles of incidence and exhibit a transmission coe cient of unity. In
addition to these complex-valued 'random' planar permittivity pro les, we construct a family of
real-valued, two-way re
ectionless and perfectly transmitting disordered permittivity pro les that
function only for a single angle of incidence and a narrow frequency range.C. G. K. acknowledges financial support from the EPSRC Centre for Doctoral Training in Electromagnetic Metamaterials Grant No. EP/L015331/1. S. A. R. H. acknowledges financial support from EPSRC program Grant No. EP/I034548/1, the Royal Society, and TATA. T. G. P. acknowledges financial support from EPSRC program Grant No. EP/I034548/1. The authors acknowledge useful discussions about localization in disordered media with J. Bertolotti
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