Control of polymorphism in coronene by the application of magnetic fields

Coronene, a polyaromatic hydrocarbon, has been crystallized for the first time in a different polymorph using a crystal growth method that utilizes magnetic fields to access a unit cell configuration that was hitherto unknown. Crystals grown in magnetic field of 1 T are larger, have a different appearance to those grown in zero field and retain their structure in ambient conditions. We identify the new form, beta-coronene, as the most stable at low temperatures. As a result of the new supramolecular configuration we report significantly altered electronic, optical and mechanical properties.Comment: 32 pages, 17 figure

The role of vitamin deficiency in liver disease: To supplement or not supplement?

Over the past few years, growing interest has been shown for the impact of dietary requirements and nutritional factors on chronic diseases. As a result, nutritional programs have been reinforced by public health policies. The precise role of micronutrients in chronic liver disease is currently receiving particular attention since abnormalities in vitamin levels are often detected. At present, treatment programs are focused on correcting vitamin deficiencies, which are frequently correlated to higher rates of comorbidities with poor outcomes. The literature reviewed here indicates that liver diseases are often related to vitamin disorders, due to both liver impairment and abnormal intake. More specific knowledge about the role of vitamins in liver disease is currently emerging from various results and recent evidence. The most significant benefits in this area may be observed when improved vitamin intake is combined with a pharmacological treatment that may also affect the progression of the liver disease, especially in the case of liver tumors. However, further studies are needed

Is There a Relationship between Objectively Measured Cognitive Changes in Cancer Patients Undergoing Chemotherapy Treatment and Their Health-related Quality of Life? A Systematic Review

Background/purpose: Many people living with cancer experience depression. Research suggests that the therapeutic effect of exercise on depression is similar to pharmacotherapy or psychological intervention, yet cancer survivors are under-exercising compared to recommended doses. Self-efficacy may be a factor to explain exercise engagement. This cross-sectional study investigated whether exercise task self-efficacy (ETSE) was associated with exercise engagement, further examining differences between cancer survivors with and without elevated depressive symptoms. \ud \ud Methods: Ninety-seven cancer survivors (60.8 ±9.9 years) were mailed self-report questionnaires on ETSE, exercise engagement, and depressive symptoms. A Hospital Anxiety and Depression Scale D cutoff score (≥8) was used to assign participants to a symptomatic (n = 34) or non-symptomatic group (n = 63). An independent t-test was used to examine differences in ETSE between groups. Correlational analyses were used to examine relationships between exercise task self-efficacy and exercise engagement. \ud \ud Results: There was a significant difference in the degree of exercise task self-efficacy between cancer survivors with (M=35.74, SD= 31.47) and without (M=57.30, SD= 26.71) depressive symptoms, t(95) =_3.56, p<0.01, with a large effect size (d =0.74). A positive association was found between ETSE and exercise engagement, r(95)= 0.49, p<0.01, which was similar for both groups. \ud \ud Conclusions: Exercise task self-efficacy appears to influence exercise engagement independently of mood status, but people with higher levels of depression symptoms tend to have lower self-efficacy. Therefore, future research should examine interventions to enhance exercise task self-efficacy, thereby potentially increasing exercise engagement in cancer survivors. Research Implications: These findings demonstrated that cancer survivors with depressive symptoms have low ETSE and that ETSE can predict exercise engagement. This suggests a role for enhancing ETSE to influence exercise engagement in cancer survivors. Future research could investigate causality between ETSE and exercise engagement and interventions to enhance ETSE. The findings of the present study could assist with more definitive research which could aid clinicians interested in behavioral change with regard to exercise engagement and improvement of depressive symptomatology in cancer survivors. Practice Implications: The findings illustrate that exercise self-efficacy predicts exercise engagement, independently of mood. Therefore, clinicians working with depressed or non-depressed cancer survivors should initially target increasing exercise self-efficacy as opposed to reinforcing the positive health benefits of increased physical activity

Simulation of High Conversion Efficiency and Open-circuit Voltages Of {\alpha}-si/poly-silicon Solar Cell

The P+ {\alpha}-Si /N+ polycrystalline solar cell is molded using the AMPS-1D device simulator to explore the new high efficiency thin film poly-silicon solar cell. In order to analyze the characteristics of this device and the thickness of N+ poly-silicon, we consider the impurity concentration in the N+ poly-silicon layer and the work function of transparent conductive oxide (TCO) in front contact in the calculation. The thickness of N+ poly-silicon has little impact on the device when the thickness varies from 20 {\mu}m to 300 {\mu}m. The effects of impurity concentration in polycrystalline are analyzed. The conclusion is drawn that the open-circuit voltage (Voc) of P+ {\alpha}-Si /N+ polycrystalline solar cell is very high, reaching 752 mV, and the conversion efficiency reaches 9.44%. Therefore, based on the above optimum parameters the study on the device formed by P+ {\alpha}-Si/N+ poly-silicon is significant in exploring the high efficiency poly-silicon solar cell.Comment: 8 pages 6figures, 1 table

Redox-Active Ferrocene grafted on H-Terminated Si(111): Electrochemical Characterization of the Charge Transport Mechanism and Dynamics

Electroactive self-assembled monolayers (SAMs) bearing a ferrocene (Fc) redox couple were chemically assembled on H-terminated semiconducting degenerate-doped n-type Si(111) substrate. This allows to create a Si(111)|organic-spacer|Fc hybrid interface, where the ferrocene moiety is covalently immobilized on the silicon, via two alkyl molecular spacers of different length. Organic monolayer formation was probed by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) and X-ray photoelectron spectroscopy (XPS) measurements, which were also used to estimate thickness and surface assembled monolayer (SAM) surface coverage. Atomic force microscopy (AFM) measurements allowed to ascertain surface morphology and roughness. The single electron transfer process, between the ferrocene redox probe and the Si electrode surface, was probed by cyclic voltammetry (CV) measurements. CVs recorded at different scan rates, in the 10 to 500 mV s−1 range, allowed to determine peak-to-peak separation, half-wave potential, and charge-transfer rate constant (KET). The experimental findings suggest that the electron transfer is a one electron quasi-reversible process. The present demonstration of surface engineering of functional redox-active organometallic molecule can be efficient in the field of molecular electronics, surface-base redox chemistry, opto-electronic applications

Effect of Benzoic Acids on Barite and Calcite Precipitation

The effect of various benzoic acids on the precipitation of barite (BaSO4) and calcite (CaCO3) was investigated. The acids varied in the number of carboxylate groups, from dibenzoic acids (phthalic, isophthalic, and terephthalic) through to the hexabenzoic acid (mellitic acid). It was found that the stereochemistry of the dibenzoic acids was important, as was the pH of the solution (trimesic acid was used as a test case and showed that greatest inhibition was achieved with all carboxylate groups deprotonated). Interestingly, for both the calcite and barite systems, mellitic acid was found to be both a potent inhibitor and a significant crystal growth modifier. In the case of barite, the presence of mellitic acid produced nanoparticles that agglomerated. The nanoparticles were found to be 20 nm in size from X-ray diffraction (XRD) line width analysis and 20-50 nm from transmission electron microscopy (TEM). Humic acid was also tested and found to form bundled fibers of barium sulfate

Marinopyrrole Derivatives as Potential Antibiotic Agents against Methicillin-Resistant Staphylococcus aureus (I)

Infections caused by drug-resistant pathogens are on the rise. The ongoing spread of methicillin-resistant Staphylococcus aureus (MRSA) strains exemplifies the urgent need for new antibiotics. The marine natural product, marinopyrrole A, was previously shown to have potent antibiotic activity against Gram-positive pathogens, including MRSA. However, its minimum inhibitory concentration (MIC) against MRSA was increased by >500 fold in the presence of 20% human serum, thus greatly limiting therapeutic potential. Here we report our discovery of a novel derivative of marinopyrrole A, designated 1a, featuring a 2–4 fold improved MIC against MRSA and significantly less susceptibility to serum inhibition. Importantly, compound 1a displayed rapid and concentration-dependent killing of MRSA. Compared to the natural product counterpart, compound 1a provides an important natural product based scaffold for further Structure Activity Relationship (SAR) and optimization

Coherent phonons and the interplay between charge density wave and Mott phases in 1TT-TaSe2_{2}

1$T$-TaSe$_{2}$ is host to coexisting strongly-correlated phases including charge density waves (CDWs) and an unusual Mott transition at low temperature. Here, we investigate coherent phonon oscillations in 1$T$-TaSe$_{2}$ using a combination of time- and angle-resolved photoemission spectroscopy (TR-ARPES) and time-resolved reflectivity (TRR). Perturbation by a femtosecond laser pulse triggers a modulation of the valence band binding energy at the $\Gamma$-point, related to the Mott gap, that is consistent with the in-plane CDW amplitude mode frequency. By contrast, TRR measurements show a modulation of the differential reflectivity comprised of multiple frequencies belonging to the distorted CDW lattice modes. Comparison of the temperature dependence of coherent and spontaneous phonons across the CDW transition shows that the amplitude mode intensity is more easily suppressed during perturbation of the CDW state by the optical excitation compared to other modes. Our results clearly identify the relationship of the in-plane CDW amplitude mode with the Mott phase in 1$T$-TaSe$_{2}$ and highlight the importance of lattice degrees of freedom.Comment: 7 pages, 4 figures, supplemental materia

Antibiotic Resistance Patterns in Invasive Group B Streptococcal Isolates

Antibiotics are used for both group B streptococcal (GBS) prevention and treatment. Active population-based surveillance for invasive GBS disease was conducted in four states during 1996–2003. Of 3813 case-isolates, 91.0% (3471) were serotyped, 77.1% (2937) had susceptibility testing, and 46.6% (3471) had both. All were sensitive to penicillin, ampicillin, cefazolin, cefotaxime, and vancomycin. Clindamycin and erythromycin resistance was 12.7% and 25.6%, respectively, and associated with serotype V (P < .001). Clindamycin resistance increased from 10.5% to 15.0% (X2 for trend 12.70; P < .001); inducible clindamycin resistance was associated with the erm genotype. Erythromycin resistance increased from 15.8% to 32.8% (X2 for trend 55.46; P < .001). While GBS remains susceptible to beta-lactams, resistance to alternative agents such as erythromycin and clindamycin is an increasing concern