1,510 research outputs found
Experimental Methods for Measuring Optical Rotatory Dispersion:Survey and Outlook
The measurement of optical rotation (OR) and optical rotatory dispersion has been finding renewed interest for some years, because of advancement in computational methods and in the performance of new experiments. Here, we shortly review the traditional and most-used experimental methods. We define and discuss the two main types of approaches in measuring OR: the intensity method and the optical null method. We report on some new results obtained by redesigning experiments based on the first approach, by adapting nonsophisticated hardware to current circular dichroism instrumentation
NIR-VCD, vibrational circular dichroism in the near-infrared: Experiments, theory and calculations
The first well documented experiments of Near Infrared Vibrational Circular
Dichroism (NIR-VCD) were performed around 1975. We review the thirty year history
of NIR-VCD, encompassing both instrumental development and theoretical/computational
methods that allow interpretation of experimental spectra, harvesting useful structural
information therefrom. We hope to stimulate interest in this still scarcely explored
spectroscopy of chiral molecule
Absorption flattening as one cause of distortion of circular dichroism spectra of Delta-RuPhen(3) . H(2)TPPS complex
To extend the model that explains why and how much absorption flattening
(AF) influences circular dichroism (CD) signals, we have investigated the interesting
case of exciton CD in the Soret region of a noncovalent complex formed by (DRuPhen3)
21 and the tetraanionic porphyrin H2TPPS. Different concentrations have been
studied by using an AF emulator and spectra simulation. The CD spectra of this compound
occasionally show distortions in the solution sampling mode with the increase of
concentration; the inhomogeneous distribution in the cell volume is due to aggregation
and is the source of the AF effect. On the basis of these results, we conclude that AF is
an important cause of distortions in CD spectra for D-RuPhen3 H2TPPS complexes and
might affect the CD bands of other aggregated systems as wel
Feline immunodeficiency virus decreases cell-cell communication and mitochondrial membrane potential.
Bullous lung disease and neurofibromatosis type-1.
Lung interstitial diseases and bullae are described as possible complications of neurofibromatosis type-1 (NF-1), a genetic disorder inherited as a autosomal-dominant trait. We report the case of a 16-year-old male non-smoker with NF-1, who presented with pneumothorax caused by ruptured lung bullae. The case of this young patient, successfully treated by video-assisted thoracoscopic resection of bullae, supports the concept that pulmonary alterations may be part of the NF-1 syndrome, rather than as an unrelated complication
Bullous lung disease and neurofibromatosis type-1
Lung interstitial diseases and bullae are described as possible complications of neurofibromatosis type-1 (NF-1), a genetic disorder inherited as a autosomal-dominant trait. We report the case of a 16-year-old male non-smoker with NF-1, who presented with pneumothorax caused by ruptured lung bullae. The case of this young patient, successfully treated by video-assisted thoracoscopic resection of bullae, supports the concept that pulmonary alterations may be part of the NF-1 syndrome, rather than as an unrelated complication
A comparative study of overtone CH- stretching vibrational circular dichroism spectra of fenchone and camphor
Near-infrared vibrational circular dichroism (VCD) spectra in the region 1500-850 nm are recorded for both
enantiomers of camphor and fenchone using a home-built dispersive instrument. Two CH-stretching overtone
regions and two CH-stretching/HCH-bending combination regions are investigated. The near-infrared VCD
data are examined and compared with the corresponding previously published data of (3R)-(+)-methylcyclopentanone
and (3R)-(+)-methylcyclohexanone. The absorption spectra of both the fundamental and overtone
regions are also considered, and the fundamental CH-stretching VCD data are taken into account, where
possible. An empirical assignment of the spectra is first considered, with special regard to the second CHstretching
overtone region. This region is then investigated by a heuristic approach based on DFT calculations,
using the hybrid functional B3LYP at the 6-31G** basis set level. Subsequently rotational strengths have
been evaluated by use of a classical model based on the contribution of polarizable groups to the optical
activity. The same models are also used to interpret the VCD spectra between 2000 and 3000 wavenumbers
for (3R)-(+)-methylcyclopentanone-d4
Harmonic and Anharmonic Features of IR and NIR Absorption and VCD Spectra of Chiral 4-X-[2.2]Paracyclophanes
The vibrational absorption spectra and vibrational circular dichroism (VCD) spectra of both enantiomers of
4-X-[2.2]paracyclophanes (X ) COOCD3, Cl, I) have been recorded for a few regions in the range of 900-
12000 cm-1. The analysis of the VCD spectra for the two IR regions, 900-1600 cm-1 and 2800-3200 cm-1,
is conducted by comparing with DFT calculations of the corresponding spectra; the latter region reveals
common motifs of vibrational modes for the three molecules for aliphatic CH stretching fundamentals, whereas
in the mid-IR region, one is able to identify specific signatures arising from the substituent groups X. In the
CH stretching region between 2900 and 2800 cm-1, we identify and interpret a group of three IR VCD bands
due to HCH bending overtone transitions in Fermi resonance with CH stretching fundamental transitions.
The analysis of the NIR region between 8000 and 9000 cm-1 for X ) COOCD3 reveals important features
of the aromatic CH stretching overtones that are of value since the aromatic CH stretching fundamentals are
almost silent. The intensifying of such overtones is attributed to electrical anharmonicity terms, which are
evaluated here by ab initio methods and compared with literature data
Dietary carbohydrate intake, dietary glycemic load and outcomes of in vitro fertilization : Findings from an observational italian cohort study
In recent decades, increasing attention has been paid to the influence of diet on reproductive health. Carbohydrates in diet affect glucose metabolism and multiple evidences showed the key role of insulin sensitivity in regulating female fertility. We designed a prospective cohort study to investigate the relation between dietary carbohydrate intake, glycemic load (GL) and the outcomes of assisted reproduction. A population of 494 female partners of couples referring to an Italian Fertility Center and eligible for in vitro fertilization (IVF) were enrolled in the study. On the day of the oocyte retrieval, information on their diet was obtained using a validated food frequency questionnaire (FFQ). We calculated the relative risk and 95% confidence interval of embryo transfer, clinical pregnancy and live birth according to the following dietary exposures: GL, glycemic index (GI) as well as the daily carbohydrate and fiber intake. A multiple regression model was used to account for the confounders. After adjusting for age, college degree, body mass index (BMI), leisure physical activity and previous assisted reproduction techniques (ART) cycles, no significant association was observed between the considered dietary exposures and the IVF outcomes. The roles of GL, carbohydrate intake and GI were assessed in strata of the cause of infertility and body mass index and no relation emerged in this further analysis. We found no clear association between the dietary carbohydrate quantity and quality and IVF outcomes in a cohort of infertile Italian women
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