Magnetism of single-crystalline Fe nanostructures.

The quantitative investigation of magnetic nanostructures by means of ferromagnetic resonance is demonstrated for single-crystalline iron nanostructures. It is shown that the single-crystalline nature leads to effects not being present in polycrystalline ones and helps to quantitatively interpret the results. First a method is presented that enables one to fabricate epitaxial Fe nanowires starting from a thin film of Fe grown under ultrahigh vacuum conditions on GaAs (110). The system allows, due to the combination of cubic and twofold magnetic anisotropy, to prepare wires whose easy axis in remanence is oriented perpendicular to the wires axis. This unique feature is only achievable in epitaxial systems. Furthermore, nearly perfect Fe nanocubes with 13.6 nm edge length prepared by wet-chemical methods are studied. While the shell of the particles is composed of either Fe3O4 or gamma-Fe2O3, the core consists of metallic Fe. Oxygen and hydrogen plasma are used to remove the ligand system and the oxide shell. The single-crystalline nature of the cubes enables one to quantitatively determine the magnetic properties of the individual particle by means of ferromagnetic resonance measurements on an ensemble together with a model based on the Landau-Lifshitz equation. The measurements reveal a magneto-crystalline anisotropy of K4 = 4.8. 10(4) J/m3 being equal to bulk value and a saturation magnetization which is reduced to M(5K) = (1.2 +/- 0.12). 10(6) A/m (70% of bulk value). The effective damping parameter alpha = 0.03 is increased by one order of magnitude with respect to bulk Fe, showing that magnetic damping in nanostructures differs from the bulk.

Influence of the carrier gas molar mass on the particle formation in a vapor phase.

The influence of the molar mass of a carrier gas on the formation of nanoparticles in the vapor phase is investigated. The function of the carrier gas atmosphere is the regulation of the particle temperature by collisions with the cluster surface. The aim of this work is to optimize the carrier gas in a simulation in order to mimic a large amount of carrier gas atoms by few gas atoms with effective parameters. In this context the efficiency of the heat exchange with the carrier gas depending on its molar mass is analyzed. As a result one finds for varying molar masses and unchanged interaction parameters a competition between the efficiency and the number of the collisions. For too small molar masses the energy exchange per collision is too small while for too high masses the carrier gas atoms become very slow, decreasing the number of collisions.

Development of an EAM potential for zinc and its application to the growth of nanoparticles.

In the context of the investigation of particle formation, a potential model by means of the embedded atom method is developed for the hexagonal close packed metal zinc. This type of model includes many-body interactions caused by delocalised electrons in metals. The effective core charge as function of the distance is calculated here by an integral over the electron distribution function rather than fitting it to experimental data. In addition, the dimer potential is included in the parameterisation because we focus on the formation of nanoparticles from the vapour phase. With this potential model, the growth of zinc clusters consisting of 125 to 1000 atoms is investigated, which takes place at elevated temperatures in a liquid-like cluster state. The growing clusters are embedded in an argon carrier gas atmosphere which regulates the cluster temperature. The average thermal expansion of the clusters and the different lattice constants are analysed. For the determination of the cluster structure, the common-neighbour analysis method is extended to hexagonal close packed surface structures. During growth, small clusters with less than approximately 60 atoms develop transient icosahedral structure before transforming into hexagonal close-packed structure. The surface of the clusters exhibits a transformation from planes with high surface energy to the most stable ones. Besides ambiguous surface structures the final clusters are almost completely in an hexagonal close packed structure.

The relation of interface properties and bulk phase stability: molecular dynamics simulations of carbon dioxide.

The limit of metastability, the so-called spinodal, is calculated for pure carbon dioxide by molecular dynamics simulation. The determination of the spinodal is based on properties of the liquid vapor interface using a recently developed method. This method relates the tangential pressure component through the vapor-liquid interface to the van der Waals loop in the two-phase region of the phase diagram. By application of the thermodynamic stability criteria, the location of the spinodal can be determined. The spinodal determined in this way is called interface spinodal here. Furthermore, the simulation provides equation of state properties in the complete metastable region of the phase diagram. The performance of different correlation equations for the density and the pressure tensor profiles with respect to the estimation of the spinodal is compared. It has been found that the interface spinodal coincides with the thermodynamic mean field spinodal within some reasonable deviation. Finally the influence of the size of the simulation box on the spinodal properties is investigated showing that the temperature-density spinodal data are independent of the interface thickness. Additional simulations using a Lennard-Jones fluid confirm these results over a range of 1.5 orders of magnitude for the systems size. A further result is that interface systems require a very long simulation time in order to obtain reliable results.

Homogeneous nucleation and growth in supersaturated zinc vapor investigated by molecular dynamics simulation.

Homogeneous nucleation and growth of zinc from supersaturated vapor are investigated by nonequilibrium molecular dynamics simulations in the temperature range from 400 to 800 K and for a supersaturation ranging from log S=2 to 11. Argon is added to the vapor phase as carrier gas to remove the latent heat from the forming zinc clusters. A new parametrization of the embedded atom method for zinc is employed for the interaction potential model. The simulation data are analyzed with respect to the nucleation rates and the critical cluster sizes by two different methods, namely, the threshold method of Yasuoka and Matsumoto [J. Chem. Phys. 109, 8451 (1998)] and the mean first passage time method for nucleation by Wedekind et al. [J. Chem. Phys. 126, 134103 (2007)]. The nucleation rates obtained by these methods differ approximately by one order of magnitude. Classical nucleation theory fails to describe the simulation data as well as the experimental data. The size of the critical cluster obtained by the mean first passage time method is significantly larger than that obtained from the nucleation theorem.

[Quantitative ultrasound for the diagnosis of osteoporosis]. / Quantitativer Ultraschall zur Osteoporosediagnostik.

Quantitative ultrasound (QUS) methods are promising tools for the assessment of the bone status in osteoporosis. The techniques are based on changes in speed and amplitude of a broadband ultrasound signal propagating through the bone. However, ultrasound propagation through the anisotropic bone is complex and cannot be described in a simple way. The devices are easy to use, inexpensive, portable, do not use ionizing radiation, and therefore have advantages compared to conventional densitometry. This review discusses the technical basics, current research, clinical applications, points of weakness, and future prospects of QUS. For better understanding ultrasound propagation through bone is visualized with a simulation software.

Telemedicine used for remote prehospital diagnosing in patients suspected of acute myocardial infarction.

INTRODUCTION: In patients with acute myocardial infarction (AMI), considerable time elapses from symptom onset until initiation of thrombolytic therapy or primary percutaneous coronary intervention. Prehospital diagnosing can reduce time delays, and remote diagnosing using telemedicine may be appropriate in areas and countries where ambulances are not staffed with physicians. OBJECTIVES: To evaluate whether it was technically feasible for physicians at a remote university hospital to diagnose ST-segment-elevation-AMI (AMI(STelev)) in patients suspected of AMI, who were transported by ambulances to a local hospital. To determine associated prehospital delays and in-hospital treatment delays. METHODS: Patients carried in telemetry equipped ambulances had 12-lead electrocardiograms (ECGs) acquired as soon as possible. En route to the local hospital the ECGs were transmitted to a remote university hospital, by use of the GSM-system. The physician on call at the university hospital interviewed the patients, who were provided with cellular phone headsets, and alerted the local hospital if signs of AMI(STelev), bundle-branch-block-AMI or malignant arrhythmia were detected. Patients transported by traditional ambulances were included in a prospective control group. RESULTS: In 214 (86%) of 250 patients prehospital diagnosing was successful. Geographically related transmission problems were the primary reason for failure. Ninety-eight per cent of transmitted electrocardiograms and obtained history takings were technically acceptable for diagnostic purposes. Door-to-needle times were shorter amongst patients with AMI(STelev) who were subjected to prehospital diagnosing (n = 13) as compared with patients transported by traditional ambulances (n = 14) (38 vs. 81 min) (P = 0.004). CONCLUSIONS: It was technically feasible to use telemedicine for remote prehospital diagnosing of patients suspected of AMI. Patients subjected to prehospital diagnosing had shorter door-to-needle times compared with a prospective control group.

Insulin action and secretion in healthy Hispanic-Mexican first-degree relatives of subjects with type 2 diabetes.

The aim of this study was to assess the early insulin secretion and insulin action of healthy non-diabetic Hispanic-Mexican subjects with and without family history of Type 2 diabetes (FHD). One hundred and twenty non-relative subjects were compared against 115 first-degree relatives of individuals with Type 2 diabetes. To assign the subjects to the correspondent group, the FHD was carefully ascertained by clinical examination of the participants' parents. Age and gender were matched criteria. Incomplete or unclear data about FHD, previous diagnosis of diabetes or chronic diseases were exclusion criteria. Subjects in both groups were required to have fasting glucose <6.1 mmol/l, and 2-h PG<7.7 mmol/l. Insulin action and secretion were estimated by HOMA (homeostasis model insulin analysis resistance index) and insulinogenic index, respectively. Logistic regression analysis showed an independent relationship between BMI and insulin resistance (HOMA score >5.0) (odds ratio, OR, 1.42, p=0.03), and between FHD and insulin resistance (OR 1.27, p=0.04). On the other hand, there was a strong and independent relationship between FHD and high early insulin secretion (insulinogenic index >0.72) (OR 1.64, p=0.01) but not between BMI and high early insulin secretion (OR 0.93, p=0.3). Healthy Mexican first-degree relatives of subjects with Type 2 diabetes show an independent relationship between FHD and both high early insulin response and decreased insulin action, whereas BMI was only related to insulin resistance.

Sarcoidosis and cancer revisited: a long-term follow-up study of 555 Danish sarcoidosis patients.

For more than 20 yrs it has been debated whether the systemic disease sarcoidosis predisposes to malignant neoplasms. The aim of this study was to examine the occurrence of cancer in Danish sarcoidosis patients observed for 9-30 yrs. The clinical data of 555 consecutive sarcoidosis patients were linked with the nationwide Danish Cancer Registry in a database, comparing the results with the expected incidence in the Danish population, adjusted for sex, age and calendar time. The sarcoidosis patients were diagnosed in two areas during the periods of 1960-1971 and 1970-1981, respectively, and followed until December 31, 1991. No excess of cancer was observed in sarcoidosis patients. A total number of 48 patients were observed with cancer (20 males and 28 females). Cancer occurred 1-29 yrs after sarcoidosis diagnosis (median 14 yrs) The observed versus expected (O/E) ratio was 1.16 (95% confidence interval (CI) 0.75-1.79) in males and 1.28 (95% CI 0.88-1.86) in females. No increased occurrence of lung cancer or malignant lymphoma (O/E ratios 0.23, 95% CI 0.00-1.25 and 1.25, 95% CI 0.02-6.95, respectively) was found. Neither age at diagnosis of sarcoidosis nor clinical sarcoidosis features were indicators of later occurrence of malignancy. The study could not confirm previous reports of an increased occurrence of malignant neoplasms in Danish sarcoidosis patients.

Degeneration of moulting glands in male crickets.

The degeneration of the prothoracic glands of the male cricket, Gryllus bimaculatus, was analyzed by using an in vitro assay for ecdysteroid release from the moulting glands in last instar nymphs as well as in adult animals, and correlated with light and transmission electron microscopy. Apoptosis was examined by the TUNEL-reaction. The ability to synthesize ecdysteroids reached a peak at the 8th day of the last larval instar, identified as the moulting peak. After adult ecdysis it decreased to barely measurable values. Prothoracic gland degeneration was initiated at the time of the moulting peak, characterized by TUNEL positive reactions, nuclear and cytoplasmatic condensation, a striking abundance of residual basal laminae; besides a great amount of autophagic vacuoles are observed. The results reveal that apoptosis and autophagy are the basic mechanisms for programmed cell death in the prothoracic gland of Gryllus bimaculatus.

[Significant extrapulmonary manifestations of sarcoidosis]. / Betydende ekstrapulmonale manifestationer af sarkoidose.

Sarcoidosis is a granulomatous multisystem disorder of unknown genesis. Although the course is most often benign and self-limiting, serious or life-threatening extrapulmonary manifestations may occur when heart, central nervous system, kidney or the haemopoietic system are involved. In these cases, corticosteroid treatment is necessary to suppress the inflammation, prevent fibrosis in vital organs, and improve the general condition.

[Pulmonary sarcoidosis]. / Pulmonal sarkoidose.

Sarcoidosis is a systemic granulomatous disorder of unknown genesis with an average annual incidence of 10/100,000 population in Denmark. The clinical picture and prognosis are dominated by the pulmonary changes in the majority of cases. The patho-anatomical picture consists of a T-lymphocyte-dominated interstitial inflammation with non-caseating epithelioid granulomas followed by fibrosis in varying degrees. The different types and courses of pulmonary disease are reviewed. Clinical examination, chest radiography, pulmonary function tests (especially the carbon dioxide diffusion capacity) and S-angiotensin-converting enzyme (S-ACE) are the most important measures of disease activity. The value of systemic corticosteroids is critically evaluated; most patients in this country can be observed without treatment because the spontaneous resolution rate is high. It is recommended that steroids should be administrated primarily in symptomatic and progressive parenchymal lung disease, or when critical or disabling extrathoracic sarcoidosis is present. If the pulmonary parenchymal infiltrates do not disappear within approximately 18 months, a course of prednisolone for at least one year should be considered to prevent disabling or even lethal pulmonary fibrosis.

[Sugar substitutes--their significance in preventing dental caries]. / Zuckerersatzstoffe--ihre Bedeutung in der Kariesbekämpfung.

Sugar is the most prominent antagonist of teeth. In the Federal Republic of Germany, approx. 2 million tons of sugar were sold for human nutrition in 1986/87. The per capita consumption was 34.8 kg. The significance of sugar substitutes can be derived from the possibility to make some particularly caries-causing confectionery types tolerable for the teeth: On the one hand, they will thus lose their caries triggering property; on the other hand, they contribute to the remineralization of carious initial lesions by stimulating the saliva. Teeth-tolerable confectionery can be specially marked. Measures and media for familiarising the public with this special "brand" are shown.

[Treatment of acute myocardial infarction--an elucidative report]. / Behandling af akut myokardieinfarkt--en klaringsrapport.

The present-day optimal treatment of patients with acute myocardial infarction (AMI) is reviewed. The prehospital phase should be as brief as possible. Emergency observation and treatment in hospital should be initiated without delay. Schematic stages for mobilization have been discarded and free mobilization is recommended. Routine acute intervention with thrombolysis is recommended for patients in whom symptoms have been present for 6-12 hours and treatment with Aspirin is recommended. Beta-blocking agents are recommended for patients with increased risk after discharge. Treatment of ventricular and supraventricular arrhythmias, block and cardiac failure are reviewed in detail. Patients without complications should be monitored for three to five days and may be discharged after seven to ten days. Exercise ECG should be carried out at discharge to assess the working capacity, ischaemia and subjective reaction. The importance of good patient information is emphasized. Cessation of smoking, control of lipids and blood pressure are important as secondary interventions. As far as possible, outpatient control should be offered after discharge. The criteria for referral to specialized cardiological departments are established both for emergency and elective referral. Patients under the age of 70 years with high risk for repeated AMI or death after discharge (with residual ischaemia) should possibly be referred for coronary arteriography.