Die chlorometrische, bromometrische und jodometrische Bestimmung des bleichenden Chlors in Hypochloriten (Bleichlaugen) und im Chlorkalk. I

Ohne Zusammenfassung     

Ion trajectories in an electrostatic ion guide for external ion source fourier transform ion cyclotron resonance mass spectrometry

An electrostatic ion guide (EIG) that consists of concentric cylinder and central wire electrodes can transport ions efficiently from an external ion source to an ion cyclotron resonance (ICR) ion trap for mass analysis, with several advantages over current injection methods. Because the electrostatic force of the EIG captures ions in a stable orbit about the wire electrode, ions with initially divergent trajectories may be redirected toward the ICR ion trap for improved ion transmission efficiency. SIMION trajectory calculations (ion kinetic energy, 1–200 eV; elevation angle, 0.30 °; azimuthal angle, 0.360°) predict that ions of m/z 1000 may be transmitted through a strong (0.01 → 3.0-T) magnetic field gradient. Judicious choice of ion source position and EIG potential minimizes the spread in ion axial kinetic energy at the ICR ion trap. Advantages of the EIG include large acceptance angle, even for ions that have large initial kinetic energy and large radial displacement with respect to the central z-axis, low ion extraction voltage (5–20 V), and efficient trapping because ions need not be accelerated to high velocity to pass through the magnetic field gradient.     

Phosphate Composition of Precipitates from Urine-like Liquors

The composition of the solid phases precipitating from urine-like liquors has been determined at 37°C over the pH range between 6 and 8 for solutions with varying amounts of magnesium, citrate, oxalate and ammonium ions. At pH ⩽7 hydroxyapatite appeared, either alone or, depending on the magnesium ion concentration, in a mixture with brushite. Stravite and calcium phosphates precipitated at pH ⩾ 7.5. No other phosphate solids were observed to precipitate from these urine-like liquors under physiological conditions. No influence on the nature of the solid phase was exerted by citrate, oxalate or ammonium ions. The variation of solid phase composition caused by changing solution composition is ascribed to kinetic rather than thermodynamic factors.     

Instance Segmentation of Multiple Myeloma Cells Using Deep-Wise Data Augmentation and Mask R-CNN

Multiple myeloma is a condition of cancer in the bone marrow that can lead to dysfunction of the body and fatal expression in the patient. Manual microscopic analysis of abnormal plasma cells, also known as multiple myeloma cells, is one of the most commonly used diagnostic methods for multiple myeloma. However, as it is a manual process, it consumes too much effort and time. Besides, it has a higher chance of human errors. This paper presents a computer-aided detection and segmentation of myeloma cells from microscopic images of the bone marrow aspiration. Two major contributions are presented in this paper. First, different Mask R-CNN models using different images, including original microscopic images, contrast-enhanced images and stained cell images, are developed to perform instance segmentation of multiple myeloma cells. As a second contribution, a deep-wise augmentation, a deep learning-based data augmentation method, is applied to increase the performance of Mask R-CNN models. Based on the experimental findings, the Mask R-CNN model using contrast-enhanced images combined with the proposed deep-wise data augmentation provides a superior performance compared to other models. It achieves a mean precision of 0.9973, mean recall of 0.8631, and mean intersection over union (IOU) of 0.9062.     

Application of the Marquardt-Levenberg procedure to the determination of discrete relaxation spectra

The application of the Marquardt-Levenberg procedure for the determination of discrete relaxation spectra from dynamic mechanical experiments on molten polymers is reviewed. It allows the calculation of a minimum number of relaxation modes, relaxation times and contribution of each time to the modulus in the terminal zone. All parameters are kept freely adjustable. The Marquardt-Levenberg procedure enables the minimisation of the χ² function between the measured values, G′(ω) and G″(ω), and those obtained by the simulated spectrum. The number of relaxation modes is smoothly increased until no improvement on the minimum value of χ² is observed. The criterium to stop the iterative procedure can be the appearance of physically improper values (negative values), but it is shown that it is better to stop the increase of the number of modes before the problem becomes ill-posed. This can be done by a comparison between the uncertainties on the calculated parameters and the values of these parameters. The uncertainties can be calculated by the Marquardt-Levenberg algorithm at each step of the calculation. The method has been tested on its ability to recover a given spectrum from model data and on a set of real experimental measurements on a monodisperse polystyrene. The calculated spectra enable calculation of the various rheological parameters. The agreement between the calculated values of G′ and G″ obtained from the recovered spectra, and the experimental ones is very good and the relative errors are very low (less than 4%). Furthermore, the calculated rheological parameters are found to be very close to those that can be evaluated from the experimental curves.     

Electrooptic effect for cold neutrons in photorefractive materials

First experimental evidence for the existence of an electrooptic effect for cold neutrons in ⁷LiNbO₃ is reported and discussed. The effect is based on the fact that in certain photorefractive crystals a light-induced space-charge field can be generated which causes a modulation of the density via the inverse piezoelectric effect. From such density structures, induced by the internal electric field, cold neutrons can be diffracted. Received: 13 November 1998 / Revised version: 21 December 1998 / Published online: 12 April 1999     

Non-Markovian relaxation in an open quantum system

Non-Markovian dynamics in open quantum systems is characterized by a time-non-locality in the equation of motion valid for the reduced density operator. An expansion of this density matrix equation with respect to Laguerre polynomials is used to tackle the time-non-locality. The applicability and the numerical limitations of the method are discussed in detail. In order to illuminate the characteristics of non-Markovian dynamics the reference example is studied of a single quantum degree of freedom moving in a harmonic potential and being embedded in a heat bath. If interpreted as the photoinduced dynamics of nuclear motion in polyatomic molecules we can suggest two clear signatures of non-Markovian dynamics observable in ultrafast optical experiments, firstly a pronounced and somewhat irregular oscillatory behavior of the vibrational level populations, and secondly a separation of the vibrational wavepacket into a double-structure. Received 12 April 2000 and Received in final form 2 September 2000     

A convenient synthesis of the novel 5H-thieno[2,3-e]-4,1,2-oxathiazepine ring system via an alkoxycarbenium ion intermediate

3-(Methoxymethoxymethyl)-2-thiophenesulfonamides and 3-hydroxymethyl-N-methoxymethyl-2-thiophenesulfonamides have been shown to undergo cyclization when treated under anhydrous acidic conditions to provide the novel 2,3-dihydro-5H-thieno[2,3-e]-4,1,2-oxathiazepine ring system. Incorporation of a primary sulfonamide group into position seven of the molecule provided compounds which inhibit human carbonic anhydrase II.     

High selectivity from configurational match/mismatch in carbon-hydrogen insertion reactions of steroidal diazoacetates catalyzed by chiral dirhodium(II) carboxamidates.

Diazo decomposition of steroidal diazoacetates, where the point of attachment is the 3-position of the steroid A-ring, catalyzed by chiral dirhodium(II) carboxamidates results in products from carbon-hydrogen insertion in high yield and selectivities. Use of S-configured catalysts shows a distinctive preference for insertion into the 3-position to form beta-lactone products. The R-configured catalysts direct insertion preferentially to the equatorial C-H bond at the 2-position. Substituents or functional groups at the 5/6-position prevent C-H insertion from taking place at the 4-position. Even in the best case with the 5/6-positions fully saturated, however, insertion into the 3-position remains competitive with insertion into the 4-position. Corresponding 3-substituted phenyldiazoacetates give only beta-lactone products, and selectivity here is highest with chiral dirhodium(II) prolinate catalysts. A model is presented to explain these results. Overall, this methodology is versatile for functionalization of the steroid A-ring at positions 2 and 3.