Stabilizing a Molecular Switch at Solid Surfaces: A Density-Functional Theory Study of Azobenzene at Cu(111), Ag(111), and Au(111)

We present a density-functional theory trend study addressing the binding of the trans-cis conformational switch azobenzene (C6H5-N=N-C6H5) at three coinage metal surfaces. From the reported detailed energetic, geometric, and electronic structure data we conclude that the governing factor for the molecule-surface interaction is a competition between covalent bonding of the central azo (-N=N-) bridge on the one hand and the surface interaction of the two closed-shell phenyl (-C6H5) rings on the other. With respect to this factor the cis conformer exhibits a more favorable gas-phase geometric structure and is thus more stabilized at the studied surfaces. With the overall binding still rather weak the relative stability of the two isomers is thereby reduced at Ag(111) and Au(111). This is significantly different at Cu(111), where the cis bonding is strong enough to even reverse the gas-phase energetic order at the level of the employed semi-local electronic exchange and correlation (xc) functional. While this actual reversal may well be affected by the deficiencies due to the approximate xc treatment, we critically discuss that the rationalization of the general effect of the surface on the meta-stable molecular states is quite robust. This should equally hold for the presented analysis of recent tip-manipulation and photo-excitation isomerization experiments from the view point of the derived bonding mechanism.Comment: 10 pages including 4 figures; related publications can be found at http://www.fhi-berlin.mpg.de/th/th.htm

Numerical solution of the higher-order linear Fredholm integro-differential-difference equation with variable coefficients

AbstractThe main aim of this paper is to apply the Legendre polynomials for the solution of the linear Fredholm integro-differential-difference equation of high order. This equation is usually difficult to solve analytically. Our approach consists of reducing the problem to a set of linear equations by expanding the approximate solution in terms of shifted Legendre polynomials with unknown coefficients. The operational matrices of delay and derivative together with the tau method are then utilized to evaluate the unknown coefficients of shifted Legendre polynomials. Illustrative examples are included to demonstrate the validity and applicability of the presented technique and a comparison is made with existing results

Novel Risk Factors for Type II Diabetes Mellitus and Coronary Heart Disease

Despite the huge advances made in the understanding of type II diabetes and coronary heart disease (CHD), these diseases still constitute a major health problem. Since the 1950s, epidemiologists focused on chronic disorders, including type II diabetes and CHD. Major aims of their research were to find predisposing factors and to reveal their pathophysiology. In the following decades, multiple traits and life-style behavioral factors were introduced and referred to as “risk factors”. The so called traditional risk factors could explain part of the diseased cases, but a proportion of cases remained unexplained. For instance, obesity was identified as a major risk factor for type II diabetes, but not all patients were overweight. Similarly, it was estimated that at least 50% of CHD events were not caused by the traditional CHD risk factors1. These observations together with the needs for widening our knowledge on the pathogenesis of type II diabetes and CHD and better accuracy of disease prediction, called for moving beyond the known risk factors. In this thesis, we made an attempt to further study two novel risk factors

Efficacy of Passiflora incarnate on anxiety relief before orthopedic surgery: A double blinded clinical trial study

Background and aims: Anxiety is the most prevalent feeling before surgery which could affect postoperative outcomes. Anti-anxiety properties of Passiflora incarnate have been reported in previous studies and this study was designed and conducted to determine properties of medicinal plant Passiflora incarnate on anxiety before orthopedic surgery in patients hospitalized in Ayatollah Kashani Hospital, Shahrekord. Methods: In this experimental study, 60 patients aged 25-50 years candidate for orthopedic surgery referring Ayatollah Kashani Hospital, Shahrekord were randomly assigned into two 30-individual groups of case and control. At the night before surgery, case group received oral Passiflora caerulea drop (500 mg, Passipy) and control group received placebo. On the day of surgery, by Spielberger Anxiety Inventory, the level of trait anxiety (individual anxious property) and state anxiety (individual anxious state) was recorded, and the patients' demographic characteristics were gathered by questionnaire. Results: There was no significant difference between two groups regarding to age, sex, and marital status. Mean score of state anxiety in case group (40.86±7.25) was lower than control group (50.63±4.58) (P=0.001), but mean score of trait anxiety was not significantly different between the two groups (P=0.303). Conclusion: Based on the results of this study, use of oral drop of Passiflora incarnate before orthopedic surgery helps to relieve patient's anxiety. Use of this extract is recommended for Anti-anxiety and sedative treatments

The reliability and validity of a designed setup for the assessment of static back extensor force and endurance in older women with and without hyperkyphosis.

ObjectiveThe purpose of this study was to investigate the intra-rater reliability and validity of a designed load cell setup for the measurement of back extensor muscle force and endurance.ParticipantsThe study sample included 19 older women with hyperkyphosis, mean age 67.0 ± 5.0 years, and 14 older women without hyperkyphosis, mean age 63.0 ± 6.0 years.MethodsMaximum back extensor force and endurance were measured in a sitting position with a designed load cell setup. Tests were performed by the same examiner on two separate days within a 72-hour interval. The intra-rater reliability of the measurements was analyzed using intraclass correlation coefficient (ICC), standard errors of measurement (SEM), and minimal detectable change (MDC). The validity of the setup was determined using Pearson correlation analysis and independent t-test.ResultsUsing our designed load cell, the values of ICC indicated very high reliability of force measurement (hyperkyphosis group: 0.96, normal group: 0.97) and high reliability of endurance measurement (hyperkyphosis group: 0.82, normal group: 0.89). For all tests, the values of SEM and MDC were low in both groups. A significant correlation between two documented forces (load cell force and target force) and significant differences in the muscle force and endurance among the two groups were found.ConclusionThe measurements of static back muscle force and endurance are reliable and valid with our designed setup in older women with and without hyperkyphosis