Search results for "SHIFT"

Huge shift of fundamental electronic absorption edge in Sr1−xBaxNb2O6 crystals at elevated temperatures

1995

Carbon-13 chemical shifts of bicyclic compounds

1970

13C NMR absorption spectra of 50 bicyclic hydrocarbons, alcohols and ketones have been measured, in addition to some terpenes. The 13C chemical shifts are approximately additive for similar compounds and can be used for the determination of molecular structure; they differ for endo- and exo-isomers, just as in proton spectra. These quite regular and predictable 13C shift differences are much larger and are caused by the 1,4-nonbonded interaction between atoms heavier than hydrogen, not by magnetic anisotropy effects.

Intramolecular charge transfer and enhanced quadratic optical non-linearities in push pull polyenes

1997

Abstract Push-pull polyenes, which have an electron-donating group (D) and an electron-withdrawing group (A) grafted on opposite ends of a conjugated polyenic chain, are of particular interest as model compounds for long-distance intramolecular charge transfer (ICT), as well as potent non-linear optical chromophores. Several series of push-pull polyenes of increasing length, combining aromatic donor moieties and various acceptor groups, have been prepared and studied. Their linear and non-linear optical properties have been investigated by performing electro-optical absorption measurements (FOAM) and electric-field-induced second-harmonic generation (EFISH) experiments in solution. Each mol…

Acidochromism of the luminescence of bis(4-pyridylethenyl)arenes

2004

Abstract A series of C 2 -symmetrical bis[( E )-2-(4-pyridyl)ethenyl]arenes has been synthesised via two-fold PO-activated olefinations. 1,4-Benzene, 1,4-naphthalene, 9,10-anthracene and 2,2′-diphenyl were used as central units. These fluorescent compounds were freely soluble in common solvents. The absorption and the emission were sensitive towards solvent polarity and acid, in solution as well as in the solid state. Depending on the concentration of acid, protonation of the ground state and/or the excited state caused reductions of the fluorescence efficiencies, accompanied by bathochromic shifts of the absorption and the emission spectra of some chromophores. The title compounds, except …

Vacuum-ultraviolet absorption of interstitial O2 and H2O molecules in SiO2 glass

2006

Abstract Vacuum-ultraviolet (VUV) absorption of O 2 and H 2 O molecules incorporated in interstitial voids in SiO 2 glass by thermal annealings was examined. Interactions of the interstitial molecules with the surrounding SiO 2 glass network lead to a redshift of the VUV absorption band of interstitial O 2 , while a blueshift of that of interstitial H 2 O, both accompanied by an increase in the intensity of the absorption bands. The Coulomb repulsion, London dispersion, and hydrogen bonding are the main interactions responsible for the modification of the VUV absorption bands.

Detection of deuterated molecules, but not of lithium hydride, in the z = 0.89 absorber toward PKS 1830−211

2020

Deuterium and lithium are light elements of high cosmological and astrophysical importance. In this work we report the first detection of deuterated molecules and a search for lithium hydride, 7LiH, at redshift z=0.89 in the spiral galaxy intercepting the line of sight to the quasar PKS1830-211. We used ALMA to observe several submillimeter lines of ND, NH2D, and HDO, and their related isotopomers NH2, NH3, and H2^18O, in absorption against the southwest image of the quasar, allowing us to derive XD/XH abundance ratios. The absorption spectra mainly consist of two distinct narrow velocity components for which we find remarkable differences. One velocity component shows XD/XH abundances that…

Redshifted X-rays from the material accreting onto TW Hya: evidence of a low-latitude accretion spot

2017

High resolution spectroscopy, providing constraints on plasma motions and temperatures, is a powerful means to investigate the structure of accretion streams in CTTS. In particular, the accretion shock region, where the accreting material is heated to temperatures of a few MK as it continues its inward bulk motion, can be probed by X-ray spectroscopy. To attempt to detect for the first time the motion of this X-ray-emitting post-shock material, we searched for a Doppler shift in the deep Chandra/HETGS observation of the CTTS TW Hya. This test should unveil the nature of this X-ray emitting plasma component in CTTS, and constrain the accretion stream geometry. We searched for a Doppler shift…

Chromo-Fluorogenic Detection of Nerve-Agent Mimics Using Triggered Cyclization Reactions in Push-Pull Dyes

2010

A family of azo and stilbene derivatives (1-9) are synthesized, and their chromo-fluorogenic behavior in the presence of nerve-agent simulants, diethylchlorophosphate (DCP), diisopropylfluorophosphate (DFP), and diethylcyanophosphate (DCNP) in acetonitrile and mixed solution of water/acetonitrile (3:1 v/v) buffered at pH 5.6 with MES, is investigated. The prepared compounds contain 2-(2-N,N-dimethylaminophenyl)ethanol or 2-[(2-N,N-dimethylamino)phenoxy]ethanol reactive groups, which are part of the conjugated pi-system of the dyes and are able to give acylation reactions with phosphonate substrates followed by a rapid intramolecular N-alkylation. The nerve-agent mimic-triggered cyclization …

Congenital primary hypothyroidism with subsequent adenomatous goiter in a Turkish patient caused by a homozygous 10-bp deletion in the thyroid peroxi…

2006

Summary Objective  Congenital primary hypothyroidism occurs in 1 of 4000 births. Whereas the majority of the cases are due to developmental defects of the thyroid gland, 20% carry a defect in thyroid hormonogenesis. We report a Turkish boy who had goitrous hypothyroidism due to a mutation in the thyroid peroxidase (TPO) gene. Design  The TPO gene was sequenced directly from genomic DNA and cDNA which was transcribed from three RNA samples harvested from different parts of the patient's excised thyroid gland. Patient  The boy was thyroidectomized because of continuing growth of his thyroid gland and development of multiple nodes suspected of malignancy by ultrasound examination. Histopatholo…

Imaging features of adrenal masses

2019

Abstract The widespread use of imaging examinations has increased the detection of incidental adrenal lesions, which are mostly benign and non-functioning adenomas. The differentiation of a benign from a malignant adrenal mass can be crucial especially in oncology patients since it would greatly affect treatment and prognosis. In this setting, imaging plays a key role in the detection and characterization of adrenal lesions, with several imaging tools which can be employed by radiologists. A thorough knowledge of the imaging features of adrenal masses is essential to better characterize these lesions, avoiding a misinterpretation of imaging findings, which frequently overlap between benign …