Esaxerenone is a new nonsteroidal mineralocorticoid receptor antagonist utilized to treat high blood pressure. Chemically, esaxerenone is a pyrrole derivative consisting of hindered rotation, which results in stereoisomers named atropisomers. Currently, no methods exist for the separation and quantification of these atropisomers. A new and accurate chiral liquid chromatographic technique was developed and validated to estimate the enantiomeric purity of esaxerenone. Polar organic chiral separation was carried out on an immobilized amylose-based chiral stationary phase (Chiralpak IG) with methanol:acetonitrile:diethylamine (9:1:0.1, v/v/v) mixture as a mobile phase. The total runtime was 15 min, and the resolution (Rs) between the atropisomers was more than 3.0. The detection and quantification thresholds for the R-atropisomer were found to be 0.03 and 0.1 µg mL?1, respectively, for a test concentration of esaxerenone (1000 µg mL?1). Over the range from the limit of quantification to 0.3 percent, the method's linearity for the R-atropisomer was excellent (R2?>?0.999). The R-atropisomer recovery varied from 95 to 102%, confirming the method’s good accuracy. For a 48-h research period, the chemical was shown to be stable.
Sodium-ion batteries (NIBs) utilize cheaper materials than lithium-ion batteries (LIBs) and can thus be used in larger scale applications. The preferred anode material is hard carbon, because sodium cannot be inserted into graphite. We apply experimental entropy profiling (EP), where the cell temperature is changed under open circuit conditions. EP has been used to characterize LIBs; here, we demonstrate the first application of EP to any NIB material. The voltage versus sodiation fraction curves (voltage profiles) of hard carbon lack clear features, consisting only of a slope and a plateau, making it difficult to clarify the structural features of hard carbon that could optimize cell performance. We find additional features through EP that are masked in the voltage profiles. We fit lattice gas models of hard carbon sodiation to experimental EP and system enthalpy, obtaining: 1. a theoretical maximum capacity, 2. interlayer versus pore filled sodium with state of charge. 相似文献
Photo-induced graft copolymerization of methyl methacrylate(MMA) onto sodium salt of partially carboxymethylated guar gum(Na-PCMGG, DS = 0.291) was carried out in an aqueous medium using ceric ammonium nitrate(CAN) as photoinitiator to synthesize a novel graft copolymer, Na-PCMGG-g-PMMA, which may find its potential application as a metal adsorbent. The influences of synthesis variables such as concentrations of photoinitiator(CAN), nitric acid and monomer(MMA) as well as reaction time, temperature and amount of substrate on the grafting yields were studied and the reaction conditions for optimum photo-grafting were evaluated. At optimum concentration, the maximum values of the grafting yields achieved were G = 271.61% and GE = 63.89%. The experimental results were found to be in very good agreement with the proposed kinetic scheme. The photo-graft copolymerization of MMA onto Na-PCMGG( DS = 0.291) was also carried out in the presence and absence of ultraviolet radiation for studying the efficiency of the photoinitiator. The influence of carboxymethyl groups introduced onto the guar gum molecules with regard to its behavior towards ultra-violet radiation induced grafting with MMA was also investigated. Photo-grafting process was confirmed and the products were characterized with the help of the spectroscopic(1H-NMR and FTIR) and SEM techniques. 相似文献
Nerium odorum, Linn. (Apocynaceae) is an important evergreen shrub. It is heat, salinity and drought tolerant. Plants with milky sap have medicinal value, mainly cardenolides, flavonoids and terpenes. It is used for wastewater purification and for restoration of riparian woodlands. In view of these facts, the study was conducted for micropropagation of N. odorum. Murashige and Skoog (MS) media supplemented with different concentrations (0.5–10.0 mg/l) of 1-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BAP) and kinetin (Kin) were used singly and in combinations. Among all the growth hormones, 2,4-D was the best for callus induction (75 % in stem and 79 % in leaf) and in combination 2,4-D and BAP (78 % in stem and 81 % in leaf). The day of callus induction started from the 19th to the 37th day. This variation is due to the differences in culture conditions and the age of explants. The fresh and dry weight and moisture content showed good growth of callus, which is used in further studies of alkaloid production. Micropropagation of this plant allows the production of clones at a fast rate and in continuous manner. This work can lead to the development of an efficient protocol for callus induction and other issues. 相似文献
On the basis of micro- and macro-morphological studies the mechanism responsible for the growth of Se–Te whiskers has been suggested. It has been shown that Sc–Te whiskers grow by layer growth mechanism in which screw dislocation is not the source of step but the growth proceeds by two-dimensional nucleation. This has been supported by the supersaturation data. The plausible mechanism for the growth of hollow whiskers has also been suggested. 相似文献
We present a novel mechanism of pattern formation behind a flat interface during directional solidification of peritectic alloys. It is shown through computational modeling that irregular oscillatory thermosolutal convection can develop in the vertical Bridgman system, even with bottom seeding and bottom cooling. The coupling of the flow oscillation near the interface with solidification leads to ordered layered structures in the solidified crystal, which agree closely with earlier experimental results. 相似文献
A 980-nm pump-induced nonlinear refractive-index (n2) change in erbium-doped (20-m) and ytterbium-doped (20-m) fibers has been measured at 1064 nm by time-delayed photorefractive beam coupling in a co-propagating and counterpropagating geometry. It was found that n2 decreases at the wavelength of the probe beam when the pump beam is present. We present a semiclassical theory based on a four-state system that accounts for the pump-induced change of n2. Both theoretical and experimental results show that a significant index change, of the order of 10%, can be obtained for cw pump powers as small as 10 mW. 相似文献
The nonlinear refractive index n2 of silica fiber (24 m) and erbium-doped fiber (10 m) is measured to within an accuracy of 5% by use of time-delayed photorefractive beam coupling of intense 53-ps, 1.064-microm pulses that experience self-phase modulation in the fibers. The resultant induced grating autocorrelation response yields a value of n2/A(eff) and a calibration standard for the fiber. A phase shift of the order of 0.19pi can be detected and is limited only by laser amplitude fluctuations. A unique advantage of this technique is its ability to measure n2 accurately in short lengths (z < or = 25 m) of fiber, whereas other approaches typically use much longer lengths of fiber (z > or = 100 m). 相似文献
Accurate segmentation of foreground objects in video scenes is critical for assuring reliable performance of vision systems
for object tracking and situational awareness in outdoor scenes. Most existing techniques for background modeling and shadow
suppression require that a number of parameters be “hand-tuned” based on environmental conditions. This paper presents two
contributions to overcome such limitations. First, we develop and demonstrate a satellite imagery based approach for selecting
appropriate background and shadow models. It is shown that the illumination conditions (i.e. cloud cover) of a scene can be
reliably inferred from visible satellite images in the local region of the camera. The second contribution presented in the
paper is introduction and evaluation of a Hybrid Cone-Cylinder Codebook (HC3) model which combines an adaptive efficient background
model with HSV-color space shadow suppression into a single coherent framework. The structure of the HC3 model allows for
seamless fusion of the satellite data. We are thereby able to exploit the fact that, for example, shadows are more pronounced
on sunny days than cloudy days, allowing for more sensitive detection. The paper presents a set of experiments using day long
sequences of videos from an operational surveillance system testbed. Results of these experimental analyses quantitatively
illustrate the benefits of using satellite imagery to inform and adaptively adjust background and shadow modeling. 相似文献
Dynamic spontaneous imbibition (DSI) plays an important role in oil reservoir characterization. Conventional equations used to characterize DSI consider neither interfacial coupling effects (ICE) nor variable inlet saturation (S*) for DSI. Yazzan et?al. (Transp Porous Media 87(1):309?C333, 2011a; 86(3):705?C717, 2011b) developed a set of equations, and a numerical solution scheme, to take into account ICE and variable S* for DSI. Based on these, a graphical user interface (GUI) simulator was built. A sensitivity analysis has been conducted to study the effect of the fluid and rock properties on DSI. The results reveal that including a variable S* has no significant impact; however, neglecting ICE results in an overestimation of the imbibition flow rate. Moreover, it is shown that the capillary and relative permeability curves determine the type of frontal advance, and that the imbibition recovery is proportional to the square root of time. 相似文献