Search results for "solution"
showing 10 items of 5638 documents
Protein dynamics observed by tunable mid-IR quantum cascade lasers across the time range from 10 ns to 1 s
2017
We have developed a spectrometer based on tunable quantum cascade lasers (QCLs) for recording time-resolved absorption spectra of proteins in the mid-infrared range. We illustrate its performance by recording time-resolved difference spectra of bacteriorhodopsin in the carboxylic range (1800–1700 cm− 1) and on the CO rebinding reaction of myoglobin (1960–1840 cm− 1), at a spectral resolution of 1 cm− 1. The spectrometric setup covers the time range from 4 ns to nearly a second with a response time of 10–15 ns. Absorption changes as low as 1 × 10− 4 are detected in single-shot experiments at t > 1 μs, and of 5 × 10− 6 in kinetics obtained after averaging 100 shots. While previous time-res…
Long-term stability study of clofarabine injection concentrate and diluted clofarabine infusion solutions
2011
Purpose: The aim of this study was to investigate the physicochemical stability of clofarabine (CAFdA) injection concentrate and ready-to-use CAFdA infusion solutions over a prolonged period of 28 days. Methods: To determine the stability of CAFdA infusion solutions, the injection concentrate (Evoltra®, 1 mg/mL, Genzyme) was diluted either with 0.9% sodium chloride or 5% glucose infusion solution. The resulting concentrations of 0.2 mg/mL or 0.6 mg/mL, respectively, were chosen to represent the lower and upper limit of the ordinary concentration range. Test solutions were stored under refrigeration (2–8°C) or at room temperature either light protected or exposed to light. CAFdA concentrati…
The Effect of Long-Term Storage on the Biological and Histological Properties of Cryopreserved Amniotic Membrane
2011
Cryopreserved amniotic membrane (AM) is widely used in ophthalmology because of its anti-angiogenic, anti-inflammatory, and wound healing promoting capabilities. A common method to conserve the tissue is the storage in cryo-medium containing 50% glycerol at -80°C. The aim of this study was to examine the influence of storage time on the sterility as well as the histological and biological properties of cryopreserved AM.Amniotic membrane from different donors was stored in cell culture media containing 50% glycerol for different time periods, on average 4 months (group 1), 15 months (group 2), and 24 months (group 3), at -80°C. Samples of the tissue and cryo-medium were examined for bacteria…
Time-Gated Raman Spectroscopy for Quantitative Determination of Solid-State Forms of Fluorescent Pharmaceuticals
2018
Raman spectroscopy is widely used for quantitative pharmaceutical analysis, but a common obstacle to its use is sample fluorescence masking the Raman signal. Time-gating provides an instrument-based method for rejecting fluorescence through temporal resolution of the spectral signal and allows Raman spectra of fluorescent materials to be obtained. An additional practical advantage is that analysis is possible in ambient lighting. This study assesses the efficacy of time-gated Raman spectroscopy for the quantitative measurement of fluorescent pharmaceuticals. Time-gated Raman spectroscopy with a 128 X (2) X 4 CMOS SPAD detector was applied for quantitative analysis of ternary mixtures of sol…
In-situ high spatial resolution LA-MC-ICPMS 230Th/U dating enables detection of small-scale age inversions in speleothems
2017
Abstract We present an in-situ method for Th and U isotope measurements by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) to determine possible age inversions of stalagmites, using a 213 nm Nd:YAG laser connected to an MC-ICPMS. Due to the low ion beam intensity of 230 Th (20–120 counts per second, cps), we carefully optimized the operating parameters to get highest possible ion beam intensities, i.e., laser fluence (25 J cm −2 ), spot size (110 μm), pulse repetition rate (20 Hz), scan speed (4 μm s −1 ), integration time (1000 s), and He and Ar gas flow (∼0.9 L min −1 and ∼0.6 L min −1 respectively). A precision (2 relative standard error, 2RSE) o…
Determination of Synchronization of Electrical Activity in the Heart by Shannon Entropy Measure
2005
In this paper we propose a new index of synchronization for the study of heart’s electrical activity during atrial fibrillation (AF). The index relies on the measure of the time delays between correspondent activations in two atrial electrograms and on the characterization of their dispersion by a measure of Shannon Entropy. The algorithm was validated on simulated signals mimicking different degree of synchronization. Results showed the index was able to discriminate among different levels of organization, provided that it works on series of at least 50 activations (time resolution of almost 10 sec during AF). Moreover, we applied the algorithm to real bipolar electrograms, obtained from a…
Determining Probability Distribution of Hillslope Peak Discharge by Using an Analytical Solution of Kinematic Wave Time of Concentration.
2016
Hillslope hydrology is fundamental for understanding the flood phenomenon and for evaluating the time of concentration. The latter is a key variable for predicting peak discharge at the basin outlet and for designing urban infrastructure facilities. There have been a multitude of studies on the hydrologic response at the hillslope scale, and the time of concentration has been derived for different approaches. One approach for deriving hillslope response utilizes, in a distributed form, the differential equations of unsteady overland flow, specifically developed at the hydrodynamic scale, in order to account for the spatial heterogeneity of soil characteristics, topography, roughness and veg…
An example of interplay between Physics and Mathematics: Exact resolution of a new class of Riccati Equations
2017
A novel recipe for exactly solving in finite terms a class of special differential Riccati equations is reported. Our procedure is entirely based on a successful resolution strategy quite recently applied to quantum dynamical time-dependent SU(2) problems. The general integral of exemplary differential Riccati equations, not previously considered in the specialized literature, is explicitly determined to illustrate both mathematical usefulness and easiness of applicability of our proposed treatment. The possibility of exploiting the general integral of a given differential Riccati equation to solve an SU(2) quantum dynamical problem, is succinctly pointed out.
High Resolution Time Domain Reflectometry for Dielectric State Monitoring in High Voltage Cables
2017
A high resolution Time Domain Reflectometry system has been designed in order to investigate the possibility of measuring with good accuracy the dielectric properties of high voltage cables insulator materials by means of Time-of-Flight measures. The system employs a dedicated Time-To-Digital Converter in order to achieve a time resolution of 90 ps. By exploiting averaging techniques the resolution has been further increased. Experimental results showed the possibility of measuring the dielectric constant with a resolution of 0.03%.
An analytical solution for multilayered beams subjected to ends loads
2014
An alternative model for multilayered beams undergoing axial, shear and bending loads applied at the beam's ends is developed. It is based on a layer-wise kinematics, which inherently fulfills the equilibrium equations at layer level and the interface continuity conditions. This kinematics is suitably expressed by introducing a set of generalized variables representative of the beam midline displacement field, which become the primary variables of the problem governing equations. As a consequence, the proposed beam model exhibits the computational characteristics of an equivalent single layer model and possesses the accuracy of layer-wise beam theories, as well. Closed form solutions for di…