Electronic structure of twisted and planar rubrene molecules: a density functional study.

X-ray absorption spectra (XAS), the density of states (DOS) and the electron density distribution of the HOMO and LUMO for flat and twisted rubrene molecules have been calculated using density functional theory (DFT). The simulated XAS spectra are validated by experimental C K-edge near-edge X-ray absorption fine structure (NEXAFS) data. We demonstrate that the NEXAFS spectra of rubrene thin films of different thicknesses can be explained in terms of different combinations of spectral intensity from the twisted and the flat randomly oriented molecules. All the fine structure of the NEXAFS spectra is well reproduced and the energetic positions of the resonances agree within a window of ±0.3 eV with the calculated XAS. Our calculation reveals that the peak at lowest photon energy (α') of the NEXAFS spectra at the lower coverage of rubrene molecules appears only from the twisted molecules. Other peaks in the case of the flat molecules appear either from the backbone or the wings, whereas, for the twisted molecules, the backbone and the wings contribute somewhat equally. Lowering of the HOMO-LUMO gap, as well as redistribution of the electron density of both the frontier orbitals, is found to take place in the case of the twisted molecule. The redistribution explains the reduction in conductivity for the twisted molecule compared to the flat one despite the lower band gap for the former. This finding will further strengthen the progress of rubrene thin film based devices.

Oxidation of rubrene thin films: an electronic structure study.

The performances of organic semiconductor devices are crucially linked with their stability at the ambient atmosphere. The evolution of electronic structures of 20 nm thick rubrene films exposed to ambient environment with time has been studied by UV and X-ray photoemission spectroscopy (UPS and XPS), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and density functional theory (DFT). XPS, NEXAFS data, and DFT calculated values suggest the formation of rubrene-epoxide and rubrene-endoperoxide through reaction of tetracene backbone with oxygen of ambient environment. Angle dependent XPS measurement indicates that the entire probed depth of the films reacts with oxygen by spending only about 120 min in ambient environment. The HOMO peak of pristine rubrene films almost disappears by exposure of 120 min to ambient environment. The evolution of the valence band (occupied states) and NEXAFS (unoccupied states) spectra indicates that the films become more insulating with exposure as the HOMO-LUMO gap increases on oxidation. Oxygen induced chemical reaction completely destroys the delocalized nature of the electron distribution in the tetracene backbone of rubrene. The results are relevant to the performance and reliability of rubrene based devices in the environment.

Observation of 2p3d(1Po)→1s3d(1De) radiative transition in He-like Si, S, and Cl ions.

We present an experimental determination of the 2p3d(1Po)→1s3d(1De) x-ray line emitted from He-like Si, S, and Cl projectile ions, excited in collisions with thin carbon foils, using a high-resolution bent-crystal spectrometer. A good agreement between the observation and state-of-the-art relativistic calculations using the multiconfiguration Dirac-Fock formalism including the Breit interaction and QED effects implies the dominance of fluorescent decay over the autoionization process for the 2p3d(^{1}P^{o}) state of He-like heavy ions. This is the first observation of the fluorescence-active doubly excited states in He-like Si, S, and Cl ions.

Core dysfunction in schizophrenia: electrophysiology trait biomarkers.

OBJECTIVE: Core symptoms of schizophrenia, particularly in the cognitive domain are hypothesized to be due to an abnormality in neural connectivity. Biomarkers of connectivity may therefore be a promising tool in exploring the aetiology of schizophrenia. We used electrophysiological methods to demonstrate abnormal visual information processing during in patients performing a simple cognitive task. METHOD: Electrophysiological recordings were acquired from 20 chronically ill, medicated patients diagnosed with either schizophrenia or schizo-affective disorder and 20 healthy volunteers while they conducted a working memory (WM) task. RESULTS: The patient group had significantly lower accuracy on the WM task and a trend for slower responses. An early visual evoked response potential was reduced in patients. Analysis of the electroencephalographic oscillations showed a decreased phase-locking factor (in the theta, beta and gamma bands) and signal power (theta frequency band). The beta and gamma oscillatory abnormalities were confined to two sets of correlated fronto and occipital electrodes. CONCLUSION: The findings of event-related potential and oscillatory abnormalities in patients with schizophrenia confirm the sensitivity of early visual information processing measurements for identification of schizophrenia phenotype. The fronto-occipital distribution of the oscillatory abnormalities replicates our findings from a schizotypal sample and implicates a possible top-down dysfunction as a vulnerability trait.

Vapor Pressure versus Temperature Relations of Common Elements.

The vapor pressure values of common elements are available in the literature over a limited temperature range and the accuracy and reliability of the reported data are not generally available. We evaluate the reliability and uncertainty of the available vapor pressure versus temperature data of fifty common pure elements and recommend vapor pressure versus temperature relations. By synthesizing the vapor pressure values from measurements reported in the literature with the values computed using the Clausius Clapeyron relation beyond the boiling point, we extend the vapor pressure range from 10-8 atm to 10 atm. We use a genetic algorithm to optimize the fitting of the vapor pressure data as a function of temperature over the extended vapor pressure range for each element. The recommended vapor pressure values are compared with the corresponding literature values to examine the reliability of the recommended values.

Structure and IR spectra of microhydrated Cl2 with an excess electron: experiment versus theory.

A working methodology to generate theoretical IR spectra following ab initio electronic structure methods is reported. Theoretical IR spectra of Cl(2)(•-)·nH(2)O clusters (n = 1-5) are generated as a case study. Excellent agreement between the calculated and the reported experimental IR spectra based on size-selected spectroscopy is observed. It is shown that uniform scaling of calculated harmonic frequencies of these hydrated clusters fail to produce accurate IR spectra. Two different scaling factors in two different regions of O-H stretching of solvent water molecules are needed to account for the anharmonic contribution. This observation is also true for Br(2)(•-)·nH(2)O and I(2)(•-)·nH(2)O systems.

Free radical reactions with the extract of brassica family.

Using different extraction protocols, the antioxidant properties of green and red cabbage extracts were evaluated in terms of the total antioxidant capacities using the 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulphonic acid) (ABTS) radical scavenging method. The results demonstrate that the total antioxidant capacity of green and red cabbages correlated well with the total phenolics and total flavonoids content present in the extracts. The ABTS radical scavenging capacity of red cabbage was much higher than that of green cabbage extract. Using time resolved absorption kinetic spectrophotometry, free radical reactions with the extracts of green and red cabbages were established. The reactions of extracts were examined using a pulse radiolysis technique. Kinetic studies indicated that extracts may act as free radical scavengers for O2(-), OH radicals and as an antioxidant to repair free-radical damage to biologically important guanosine radical.

Staged complex abdominal wall hernia repair in morbidly obese patients.

PURPOSE: The repair of complex abdominal wall hernias in morbidly obese patients is often associated with a higher risk of complications and hernia recurrences. Improvement in obesity and its associated metabolic complications are hypothesized to improve hernia repair outcomes. This study analyzes outcomes from morbidly obese patients who underwent bariatric surgery with staged complex abdominal wall reconstruction at Creighton University Medical Center (CUMC). METHODS: This retrospective study included morbidly obese patients with complex abdominal wall hernia, who underwent bariatric surgery with staged abdominal wall reconstruction. Data points collected included patient demographics, obesity-related co-morbidities, pre-operative BMI, EBMIL at 12 months, hernia characteristics, postoperative complications, BMI at time of hernia repair, and hernia recurrence. RESULTS: Twelve patients with an average BMI of 48 and complex abdominal wall hernias (mean width 14.0 cm) met inclusion criteria. Seven patients (58%) had significant loss of domain. Bariatric procedures included six laparoscopic sleeve gastrectomies (LSG), three laparoscopic Roux-en-Y gastric bypasses (LRNYGB), and three revisional procedures (2 vertical band gastroplasties to LRNYGB and 1 LRNYGB revision). At 12-month follow-up, the mean excess BMI loss (EBMIL) was 64.6%. The average time to staged complex abdominal wall reconstruction was 22.3 months. Two non-elective hernia repairs were performed due to one incarceration and one strangulation. There were no recurrences after an average follow-up of 21.9 months. CONCLUSIONS: In this study, staged mesh repair of complex abdominal wall hernias after bariatric surgery in morbidly obese patients was associated with acceptable morbidity and no hernia recurrences at approximately 1.5 year follow-up.

Quantum chemical study on UV-vis spectra of microhydrated iodine dimer radical anion.

UV-vis spectral properties of I(2)(*-).nH(2)O systems are reported based on ab initio quantum chemical calculations. Second order Moller-Plesset perturbation theory is applied for geometry search and time dependent density functional theory is applied to study excited state properties. Relativistic corrections are considered for all the calculations. Geometry search is carried out applying simulated annealing combined with Monte Carlo sampling method. Strong optical absorption band of these hydrated clusters, I(2)(*-).nH(2)O in the UV-vis region is assigned to sigma(g) --> sigma(u)* type valence electron transition in contrast to charge transfer to solvent spectra in I(-).nH(2)O systems. Simulated optical absorption profile of I(2)(*-).8H(2)O system is in excellent agreement with the reported aqueous phase spectrum of iodine dimer radical anion.

Numerical simulations of different sectoral contributions to post monsoon pollution over Delhi.

The National Capital Region (NCR) of India, Delhi, has experienced high post-monsoon pollution along with several peak pollution episodes in recent years. Diwali, the festival of lights, which is among the biggest festivals of India celebrated during the post-monsoon season, is also considered a pollution event associated as it is with the lighting of a large number of firecrackers. 2016 Diwali pollution episode continued for a week creating severe discomfort to residents of Delhi, prompting the judiciary to ban the sale and use of firecrackers in Delhi from 2017 onwards. The current study analyzes different sectoral and temporal emissions contribution to the 2016 post monsoonal pollution episode over Delhi using a fully coupled chemical transport model. The findings of the study indicate that aerosols produced from crop residue open burning at the northwestern states contributed more than 60% of the total simulated surface concentration during the period under study. Model experimental simulations show that despite emissions from within the city, what explains the severity of pollution over Delhi during the period under consideration is an additional pollution load emanating from these intense crop open burning sessions from nearby areas. Further, model simulations show that while Diwali emissions can elevate the pollution load over Delhi, the effects do not last beyond 48 h. It is found that the stagnation of the pollutants several days beyond the 2016 Diwali day was due to favorable meteorological conditions like low surface temperature, lower boundary layer height, and weak northwesterly winds. The study shows that in order to improve air quality in Delhi during the post-monsoon period, mitigation efforts should target the adjacent rural areas, especially when there is massive burning of crop residue in those areas.

A comparative study of the ultrastructure of microvilli in the epithelium of small and large intestine of mice.

A comparative analysis of the fine structure of the microvilli on jejunal and colonic epithelial cells of the mouse intestine has been made. The microvilli in these two locations demonstrate a remarkably similar fine structure with respect to the thickness of the plasma membrane, the extent of the filament-free zone, and the characteristics of the microfilaments situated within the microvillous core. Some of the core microfilaments appear to continue across the plasma membrane limiting the tip of the microvillus. The main difference between the microvilli of small intestine and colon is in the extent and organization of the surface coat. In the small intestine, in addition to the commonly observed thin surface "fuzz," occasional areas of the jejunal villus show a more conspicuous surface coat covering the tips of the microvilli. Evidence has been put forward which indicates that the surface coat is an integral part of the epithelial cells. In contrast to the jejunal epithelium, the colonic epithelium is endowed with a thicker surface coat. Variations in the organization of the surface coat at different levels of the colonic crypts have also been noted. The functional significance of these variations in the surface coat is discussed.

Demonstration of the fuzzy surface coat of rat intestinal microvilli by freeze-etching.

In freeze-etch replicas of epithelial cells of rat rectum, the fuzzy surface coat is composed of discrete filaments which are aligned in parallel with each other and with the long axes of the microvilli.

Biosynthesis of high density lipoprotein by chicken liver: intracellular transport and proteolytic processing of nascent apolipoprotein A-1.

To study the in vivo processing and secretion of Apolipoprotein A-I (Apo A-I), young chickens were administered individual L-[3H]amino acids intravenously and the time of intracellular transport of nascent Apo A-I from rough endoplasmic reticulum (RER) to the Golgi apparatus was measured. Within 3 to 9 min there was maximal incorporation of radioactivity into Apo A-I in both the RER and the Golgi cell fractions. By contrast, the majority of radioactive albumin was also present in the RER by 3 to 9 min, but did not reach peak amounts in the Golgi fraction until 9 to 25 min. Both radioactive Apo A-I and albumin appeared in the blood at about the same time (between 20 and 30 min). NH2-terminal amino acid sequence analysis of nascent intracellular Apo A-I showed that it contains a pro-hexapeptide extension identical to that of human Apo A-I. After 30 min of administration of radioactive amino acids radioactive Apo A-I was isolated by immunoprecipitation from the liver and serum. NH2-terminal sequence analysis of 20 amino acids indicated that chicken liver contained an equal mixture of nascent pro-Apo A-I and fully processed Apo A-I, whereas the serum only contained processed Apo A-I. Further studies showed that the RER only contained pro-Apo A-I, whereas a mixture of pro-Apo A-I and processed Apo A-I was found in the Golgi complex. These results indicate that, in chicken hepatocytes, there is a more rapid transport of Apo A-I than of albumin from the RER to the Golgi cell fractions, and that Apo A-I remains in the Golgi apparatus for a longer period of time before it is secreted into the blood. In addition these studies show that the in vivo proteolytic processing of chicken pro-Apo A-I to Apo A-I occurs in the Golgi cell fractions.

Vibrational analysis of I2*- x nCO2 clusters (n = 1-10): a first principle study on microsolvation.

Structure, stability, and vibrational IR and Raman spectra of I(2)(*-) x nCO(2) clusters (n = 1-10) are reported based on first-principle electronic structure calculations. Several close-lying minimum energy structures are predicted for these solvated clusters following the quasi Newton-Raphson procedure of geometry optimization. Search strategy based on Monte-Carlo simulated annealing is also applied to find out the global minimum energy structures of these clusters. Successive addition of solvent CO(2) molecules to the negatively charged diatomic solute, I(2)(*-), is fairly symmetrical. Energy parameters of these solvated clusters are calculated following second-order Moller-Plesset perturbation (MP2) as well as coupled cluster theory with 6-311+G(d) set of basis function (I atom is treated with 6-311G(d) set of basis function). The excess electron in these solvated clusters is observed to be localized mainly over the two I atoms. Average interaction energy between the anionic solute, I(2)(*-), and a solvent CO(2) molecule is approximately 129 meV in I(2)(*-) x nCO(2) clusters, and the average interaction energy between two solvent CO(2) molecules is approximately 85 meV in the case of neutral (CO(2))(n) clusters at MP2 level of theory. IR spectra show similar features in all these solvated clusters, depicting a strong band at approximately 2330 cm(-1) for C-O stretching and a weak band at approximately 650 cm(-1) for CO(2) bending modes. Degeneracy of the bending mode of a free solvent CO(2) unit gets lifted when it interacts with the charged solute I(2)(*-) to form a molecular cluster because of the change in structure of solvent CO(2) units. The vibrational band at the bending region of CO(2) in the Raman spectra of these anionic clusters shows a characteristic feature for the formation of I(2)(*-) x nCO(2) clusters showing a Raman band at approximately 650 cm(-1).

Microhydration of NO3(-): a theoretical study on structure, stability and IR spectra.

A systematic study on the structure and stability of nitrate anion hydrated clusters, NO3(-) x n H2O (n = 1-8) are carried out by applying first principle electronic structure methods. Several possible initial structures are considered for each size cluster to locate equilibrium geometry by applying a correlated hybrid density functional with 6-311++G(d,p) basis function. Three different types of arrangements, namely, symmetrical double hydrogen bonding, single hydrogen bonding and inter-water hydrogen bonding are obtained in these hydrated clusters. A structure having inter-water hydrogen bonding is more stable compared to other arrangements. Surface structures are predicted to be more stable over interior structures. Up to five solvent H2O molecules can stay around solute NO3(-) anion in structures having an inter-water hydrogen-bonded cyclic network. A linear correlation is obtained for weighted average solvent stabilization energy with the size (n) of the hydrated cluster. Distinctly different shifts of IR bands are observed in these hydrated clusters for different kinds of bonding environments of O-H and N=O stretching modes compared to isolated H2O and NO3(-) anion. Weighted average IR spectra are calculated on the basis of statistical population of individual configurations of each size cluster at 150 K.

In vivo radioprotection by 5-aminosalicylic acid.

The radioprotective effect of 5-aminosalicylic acid (5ASA) was investigated in mouse bone marrow. The present study was aimed at investigating the radioprotective effect of pre-irradiation treatment with 5ASA against a range of whole-body lethal (8-11 Gy) and sublethal (1-4 Gy) doses of gamma-radiation (RT) in adult Swiss albino mice. Protection against lethal irradiation was evaluated from 30-day mouse survival and against sublethal doses was assessed from chromosomal aberrations in the bone marrow 24 h after irradiation. An intraperitoneal injection of 5ASA at a dose of 25mg/kg body weight (b. wt.) 30 min before lethal RT increased survival, giving a dose modification factor (DMF) of 1.08. Injection of 5ASA (25 mg/kg b. wt.) 60 or 30 min before or within 15 min after 3 Gy whole body RT resulted in a significant decrease in the radiation-induced aberrant metaphases, at 24 h post-irradiation. Maximum effect was seen when the drug was administered 30 min before irradiation. 5ASA (25 mg/kg b. wt.) significantly reduced the number of aberrant metaphases and the different types of aberrations at all the radiation doses (1-4 Gy) tested, giving a DMFs of 1.43 for number of aberrant metaphases. 5ASA pretreatment also significantly enhanced the endogenous spleen colonies in mouse exposed to 11 Gy RT. Pretreatment with 5ASA, protected plasmid DNA (pGEM-7Zf) against breakage induced by RT and Fenton reactants. Using nanosecond pulse radiolysis technique, the bimolecular rate constant of the reaction of 5ASA with hydroxyl radical was found to be 6.7x10(9)M(-1)s(-1). The p53 and p21 protein levels of bone marrow and spleen were evaluated to identify the specific molecular mechanisms. Both p53 and p21 increased 24h after 6 Gy irradiation, while treatment with 5ASA inhibited this RT-induced increase. Therefore, the present data suggest that 5ASA pretreatment decreases death caused by RT-induced gastrointestinal and hemopoeitic syndromes. The proposed mechanism of radioprotection by 5ASA is through the inhibition of damage to DNA, lipids, and proteins; and prevention of RT-induced increased expression of p53 and p21.

Vertical detachment energy of I2*- . nCO2 clusters (n=1-8): experiment versus theory.

We report vertical detachment energy (VDE) of I(2) (-)nCO(2) clusters (n=1-8) based on first principle calculations with atomic basis functions. Calculated VDE values of these solvated clusters are in excellent agreement with the reported measured values following photoelectron spectroscopy of size selected I(2) (-)nCO(2) clusters. Bulk VDE of iodine dimer radical anion in solvent CO(2) is predicted as 5.29 eV applying a simple model of extrapolation.

Effect of donor orientation on ultrafast intermolecular electron transfer in coumarin-amine systems.

Effect of donor amine orientation on nondiffusive ultrafast intermolecular electron transfer (ET) reactions in coumarin-amine systems has been investigated using femtosecond fluorescence upconversion measurements. Intermolecular ET from different aromatic and aliphatic amines used as donor solvents to the excited coumarin-151 (C151) acceptor occurs with ultrafast rates such that the shortest fluorescence lifetime component (tau(1)) is the measure of the fastest ET rate (tau(1)=tau(ET) (fast)=(k(ET) (fast))(-1)), assigned to the C151-amine contact pairs in which amine donors are properly oriented with respect to C151 to maximize the acceptor-donor electronic coupling (V(el)). It is interestingly observed that as the amine solvents are diluted by suitable diluents (either keeping solvent dielectric constant similar or with increasing dielectric constant), the tau(1) remains almost in the similar range as long as the amine dilution does not cross a certain critical limit, which in terms of the amine mole fraction (x(A)) is found to be approximately 0.4 for aromatic amines and approximately 0.8 for aliphatic amines. Beyond these dilutions in the two respective cases of the amine systems, the tau(1) values are seen to increase very sharply. The large difference in the critical x(A) values involving aromatic and aliphatic amine donors has been rationalized in terms of the largely different orientational restrictions for the ET reactions as imposed by the aliphatic (n-type) and aromatic (pi-type) nature of the amine donors [A. K. Satpati et al., J. Mol. Struct. 878, 84 (2008)]. Since the highest occupied molecular orbital (HOMO) of the n-type aliphatic amines is mostly centralized at the amino nitrogen, only some specific orientations of these amines with respect to the close-contact acceptor dye [also of pi-character; A. K. Satpati et al., J. Mol. Struct. 878, 84 (2008) and E. W. Castner et al., J. Phys. Chem. A 104, 2869 (2000)] can give suitable V(el) and thus ultrafast ET reaction. In contrary, the HOMO of the pi-type aromatic amines is largely distributed throughout the whole molecule and thus most of the orientations of these amines can give significant V(el) for ultrafast ET reactions with close-contact C151 dyes.

Zinc as a marker in viscera of suspected metal phosphide poisoning: a study by neutron activation analysis.

Zinc as a marker element in the viscera of suspected metal phosphide poisoning has been studied during the present work. Neutron activation analysis (NAA) has been employed to detect and quantify the concentration of zinc in the viscera/stomach portion. The methodology has been developed on simulated and real life viscera samples to quantify the amount of zinc using NAA. The results obtained by NAA for real-life samples have been validated using a complementary analytical technique (viz. differential pulse anodic stripping voltammetry), and the values obtained were in good agreement, within +/- 5-8%. This exercise could be useful in medico-legal field for framing a definitive opinion about zinc phosphide poisoning.