Studies on the chemistry of 1,4-oxazines. 18. Synthesis of tricyclic 1,4-benzoxazines via nucleophilic substitution of activated precursors

Starting from activated benzoxazines 1 and 2 new synthetic pathways to the tricyclic compounds 4, 9, 12 and 16 are described. Reaction of the hydrazides 17a,b with thionylchloride leads to the novel thiatriazolo-benzoxazines 18a,b .     

Automatic Bi trace analysis integrated in the manufacturing process of turbine blades

Summary In the manufacture of aero-engine components, auxiliary materials are used which impair mechanical properties if they are not completely removed afterwards. Taking the manufacture of turbine blades and vanes as an example, this investigation shows how the inclusion of an analysis stage in the fully-automatic production cycle makes it possible to monitor the thoroughness of the cleaning process. As indicator, the element Bi is used; the matrix consists of concentrated nitric acid with a high nickel content. Because of the imposition of a limiting value, it must be possible to determine differences in the Bi-content of 20 g/l. The main part of the paper concerns the selection of the most optimum process. The results using two types of AAS coupled with hydride generation are presented. The success of the complete system is illustrated by the summarized results.     

An Exploratory Study on the Complexity and Machine Learning Predictability of Stock Market Data

This paper shows if and how the predictability and complexity of stock market data changed over the last half-century and what influence the M1 money supply has. We use three different machine learning algorithms, i.e., a stochastic gradient descent linear regression, a lasso regression, and an XGBoost tree regression, to test the predictability of two stock market indices, the Dow Jones Industrial Average and the NASDAQ (National Association of Securities Dealers Automated Quotations) Composite. In addition, all data under study are discussed in the context of a variety of measures of signal complexity. The results of this complexity analysis are then linked with the machine learning results to discover trends and correlations between predictability and complexity. Our results show a decrease in predictability and an increase in complexity for more recent years. We find a correlation between approximate entropy, sample entropy, and the predictability of the employed machine learning algorithms on the data under study. This link between the predictability of machine learning algorithms and the mentioned entropy measures has not been shown before. It should be considered when analyzing and predicting complex time series data, e.g., stock market data, to e.g., identify regions of increased predictability.     

Notes on D-optimal designs

The purpose of this paper is to exhibit new infinite families of D-optimal (0, 1)-matrices. We show that Hadamard designs lead to D-optimal matrices of size (j, mj) and (j − 1, mj), for certain integers j ≡ 3 (mod 4) and all positive integers m. For j a power of a prime and j ≡ 1 (mod 4), supplementary difference sets lead to D-optimal matrices of size (j, 2mj) and (j − 1, 2mj), for all positive integers m. We also show that for a given j and d sufficiently large, about half of the entries in each column of a D-optimal matrix are ones. This leads to a new relationship between D-optimality for (0, 1)-matrices and for (±1)-matrices. Known results about D-optimal (±1)-matrices are then used to obtain new D-optimal (0, 1)-matrices.     

The thermal contact problem in nano- and micro-scale photothermal measurements

Thermal contact resistance between two solids is discussed with regard to its influence on the measurements of temperature and thermo-physical parameters in micro- and nano-structures. Two important applications are considered: thin film coatings on substrates and local measurements with a nano-probe in scanning thermal microscopy. The mechanical contact of a copper layer on carbon is measured by adhesion strength experiments and correlated to the thermal transport across the interface deduced from infrared radiometric measurements. A novel quantity the thermal wave contrast is introduced which takes into account the interface resistance and modifications of the coating and substrates at the interface. With regard to scanning thermal microscopy the contact resistance problem is discussed for 3ω-measurements in the active mode and for temperature measurements in the passive mode. It is shown that the thermo-elastic response can offer a means to avoid the influence of the thermal contact resistance on local temperature measurements.     

Photothermal and micro-thermal characterization of metal coated diamond crystallites

Photoacoustic effect and scanning near field microscopy have been applied to characterise the thermal properties of diamond crystallites which were coated by a Cu film, a Cr-film and a Cr-Cu film. The Cu-coated diamond exhibits a considerable thermal barrier at the Cu-diamond interface which had disappeared for the crystallites with a thin bond Cr-layer between diamond and Cu. The local inspection of the thermal conductivity with a thermal nano-probe operated in the 3ω-mode reveals slight local variations of the thermal conductivity of the Cr-coated crystallite.     

Detection of myocardial viability by low-dose dobutamine Cine MR imaging

The purpose of this work was to test the diagnostic value of dobutamine stress magnetic resonance imaging (MRI) for predicting recovery of regional myocardial contractility after revascularization. Cardiac wall motion abnormalities are due to either non-viable and/or scarred, or viable, but hibernating, myocardial tissue. Dobutamine stress leads to increased systolic wall thickening only in viable myocardium. Twenty-five patients with akinetic or dyskinetic myocardial regions were examined with a Cine FLASH-2D sequence at rest and during dobutamine stress (10 μg/kg/min). Patients were re-examined at rest 3, and in case of persisting wall motion defects, 6 months after revascularization. Criterion of viability was increasing end-systolic wall thickening during stress and/or at follow-up. Akinetic regions related either to the LAD (n = 19) or to the RCA (n = 6) were judged viable if >=50% of the affected segments improved. MR studies were completed in all subjects without arrhythmia or need for early terminations due to symptoms. Sensitivity, specificity, and positive predictive value for the prediction of myocardial viability were 61%, 90%, and 87% for the segment-related analysis, and 76%, 100%, and 100% for the patient-related analysis based on coronary artery distribution, respectively. Dobutamine stress MRI allows to predict global functional recovery of akinetic myocardial regions after revascularization with a high positive predictive value and high specificity.     

Change in the body temperature of healthy term infant over the first 72 hours of life

OBJECTIVE: To determine the range of body temperature in a group of healthy Chinese term neonates over the first 72 hours of life and to assess the influence of body weight, gestational age and route of delivery.METHOD: All 200 consecutive cases of neonates delivered at our hospital from March to August 2001 were included in this retrospective study. Temperatures were measured immediately after delivery, after 30 minutes, 1 hour, 2 hours, 8 hours and 15 hours and on the 2nd and 3rd day. Axillary temperatures ranging from 36.5 degrees C to 37 degrees C were regarded as normal. No cases of maternal fever or systemic infection of the newborns were discovered. All infants were discharged in good general condition. RESULTS: The mean rectal temperature at birth was 37.19 degrees C. The lowest average temperature was reached at 1 hour after delivery (36.54 degrees C) with a significant difference between natural delivery (36.48 degrees C) and section (36.59 degrees C) (P<0.05). Temperature subsequently rose to 36.70 degrees C at 8 hours and 36.78 degrees C at 15 hours (P<0.05). Hypothermia was seen in 51.8% and hypothermia in 42.5% of the patients. On the 3rd day after delivery, 96% of all temperatures were in the normal range. A significant relation was found between hypothermia and both low birth weight (P<0.001) and low gestational age (P<0.05). CONCLUSION: The reference range presently used did not include all physiological temperatures in the first 72 hours of life. Considering other factors, such as birth weight, route of delivery, gestational age and body temperature on the 2nd and 3rd day of life, may help to correctly assess the significance of temperatures beyond the reference range.