Interaction phenomena in graphene seen through quantum capacitance

Capacitance measurements provide a powerful means of probing the density of states. The technique has proved particularly successful in studying 2D electron systems, revealing a number of interesting many-body effects. Here, we use large-area high-quality graphene capacitors to study behavior of the density of states in this material in zero and high magnetic fields. Clear renormalization of the linear spectrum due to electron–electron interactions is observed in zero field. Quantizing fields lead to splitting of the spin- and valley-degenerate Landau levels into quartets separated by interaction-enhanced energy gaps. These many-body states exhibit negative compressibility but the compressibility returns to positive in ultrahigh B. The reentrant behavior is attributed to a competition between field-enhanced interactions and nascent fractional states.     

Correlation between oral health-related quality of life and orthodontic treatment need in children and adolescents—a prospective interdisciplinary multicentre cohort study

Purpose

Oral health-related quality of life (OHRQoL) is a construct for assessing the self-perceived oral health of patients. The aim of this study was to investigate the correlation between OHRQoL and orthodontic treatment need in consideration of demographic and psychological factors.

Patients and methods

This multicentre study included 250 patients with an indication for orthodontic diagnostics. In cooperation with the Institute of Clinical Psychology at the University of Würzburg, validated and internationally acknowledged questionnaires were selected to assess OHRQoL (COHIP-G19) and health-related quality of life (HRQOL). Self-esteem and behavioural problems were taken into consideration as possible psychological factors. Orthodontic treatment need was assessed using the Index of Orthodontic Treatment Need—Dental Health Component (IOTN-DHC), the Index of Orthodontic Treatment Need—Aesthetic Component (IOTN-AC) and the Dental Aesthetic Index (DAI). Possible significant correlations between the collected parameters and OHRQoL were evaluated by means of linear regression analysis.

Results

Objective orthodontic treatment need (IOTN-DHC and DAI) was significantly correlated with OHRQoL. Further factors significantly influencing OHRQoL in children and adolescents were age, HRQOL, self-esteem and behavioural problems.

Conclusions

Objective orthodontic treatment need significantly influences OHRQoL in children and adolescents. Further studies are required to investigate if OHRQoL may be improved by correcting misaligned teeth and jaws.

     

Usefulness of BNP-administration in cardiac surgery: animal model

OBJECTIVE: The pharmacologic properties of Brain natriuretic peptide make it a favourable substance to use after cardiac operations. The goal of this study was to evaluate the effect of BNP following cardio-pulmonary bypass (CPB). METHOD: Nineteen pigs were operated on using CPB. One group received BNP and the control group received placebo. A 30-minute ischemic episode was simulated. Following declamping, BNP was administered by an IV bolus, followed by an infusion for 60 minutes. Hemodynamic and clinical chemistry parameters were documented, as well as the amount of catecholamines. RESULTS: The Cardiac output and Cardiac Index in the BNP group were significantly higher 60 minutes after ending CPB. Seven of ten animals in the control group needed catecholamines at the end of the experiment, whereas none of the animals in the BNP group did at this juncture. Creatine kinase and Lactate were significantly lower. CONCLUSION: BNP is a well-tolerated agent that could present a new treatment option for heart failure following cardiac surgery. Hemodynamics are greatly improved with almost no need for pharmacological support.     

Administration of brain natriuretic peptide improves cardiac function following operations using extracorporeal circulation in an animal model

The critical phase during cardiosurgical procedures is weaning the diseased heart from the ECC (extracorporeal circulation). Post-ischaemic heart failure sometimes requires the administration of inotropic and/or vasconstrictive agents. The natriuretic peptides influence pre- and after-load through their natriuretic, diuretic and vasodilating actions. To date, there are only a few reports describing the therapeutic effect of BNP (brain natriuretic peptide) administration during cardiosurgical procedures. The aim of the present study was to evaluate the effect of BNP administration following ECC in an animal model. Surgery was performed on 20 pigs using ECC. A 30-min ischaemic episode was simulated. Following de-clamping, BNP was administered to the BNP group (n=10) by an i.v. (intravenous) bolus at 0.3 microg x kg(-1) of body weight x min(-1), followed by an infusion at a rate of 0.015 microg x kg(-1) of body weight x min(-1) for 60 min. The animals in the control group (n=10) received a saline solution instead of BNP. Haemodynamic and clinical chemistry parameters as well as the amount of catecholamines that were required were measured. All of the animals in the BNP group had a significantly better cardiac output and cardiac index at the end of the experiment. Seven out of 10 animals from the control group required catecholamines, whereas only one animal from the BNP group did. Creatine kinase levels were significantly lower in the BNP group. Systemic vascular resistance was markedly lower in the BNP group. In conclusion, administration of BNP is highly effective in treating post-ischaemic heart failure following ECC. Haemodynamics are greatly improved, and there is almost no need for pharmacological support.     

Usefulness of BNP-administration in cardiac surgery: Animal model

Objective. The pharmacologic properties of Brain natriuretic peptide make it a favourable substance to use after cardiac operations. The goal of this study was to evaluate the effect of BNP following cardio-pulmonary bypass (CPB). Method. Nineteen pigs were operated on using CPB. One group received BNP and the control group received placebo. A 30-minute ischemic episode was simulated. Following declamping, BNP was administered by an IV bolus, followed by an infusion for 60 minutes. Hemodynamic and clinical chemistry parameters were documented, as well as the amount of catecholamines. Results. The Cardiac output and Cardiac Index in the BNP group were significantly higher 60 minutes after ending CPB. Seven of ten animals in the control group needed catecholamines at the end of the experiment, whereas none of the animals in the BNP group did at this juncture. Creatine kinase and Lactate were significantly lower. Conclusion. BNP is a well-tolerated agent that could present a new treatment option for heart failure following cardiac surgery. Hemodynamics are greatly improved with almost no need for pharmacological support.     

Two-dimensional atomic crystals

We report free-standing atomic crystals that are strictly 2D and can be viewed as individual atomic planes pulled out of bulk crystals or as unrolled single-wall nanotubes. By using micromechanical cleavage, we have prepared and studied a variety of 2D crystals including single layers of boron nitride, graphite, several dichalcogenides, and complex oxides. These atomically thin sheets (essentially gigantic 2D molecules unprotected from the immediate environment) are stable under ambient conditions, exhibit high crystal quality, and are continuous on a macroscopic scale.