Simultaneous determination of eight short‐chain aliphatic amines in drug substances by HPLC with diode array detection after derivatization with halonitrobenzenes

Short‐chain aliphatic amines are a class of hazardous impurities in drug substances. A simple method, involving derivatization followed by high‐performance liquid chromatography with diode array detection, has been developed for residue determination of eight aliphatic amines simultaneously in drug substances. Different halonitrobenzenes derivatization reagents were systematically compared. As a result, 1‐fluoro‐2‐nitro‐4‐(trifluoromethyl)benzene was selected since the derivatization effectively shifted the absorption wavelength to the visible region (400–450 nm), where most drug substances, impurities and even the derivatization reagent absorb very weakly. Due to the redshift effect, interference was minimized and adequately low limits of quantitation were reached (0.24–0.80 nmol/mL). Moreover, the derivatization reaction was readily carried out in dimethyl sulfoxide at room temperature for 1 h using N ,N‐diisopropylethylamine as catalyst to achieve the highest yield. Without any pre‐treatment, the derivatives were analyzed by high‐performance liquid chromatography with diode array detection. The high stability of the derivatives within 24 h at room temperature (RSD<1.04%) further facilitated the simultaneous preparation and consecutive analysis of quantities of samples. Finally, the proposed method was successfully applied for residue determination of eight aliphatic amines simultaneously in eight drug substance samples. This study could be helpful for the routine analysis and residue control of aliphatic amines in drug substances.     

Effect of bromine substituent on optical properties of aryl compounds

Substituents significantly affect optical properties of organic compounds. In this study, a series of organic compounds were synthesized. Ultraviolet‐visible and cyclic voltammetry spectra were determined. The relationships between the number of π electron in an aryl ring and the redshift (and molecular orbital energy levels) were studied. To investigate mechanisms of the bromine substituent effects, theoretical calculations were carried out. Ultraviolet‐visible spectra of bromine‐containing compounds exhibit obvious redshifts (0.04‐0.17 eV) of the maximal absorption wavelengths and enhanced absorbance (11%‐57%) compared with corresponding reference compounds. The lowest unoccupied and highest occupied molecular orbital energy levels of compounds containing bromine substituents are 0.05 to 0.60 and 0.02 to 0.40 eV lower than that of corresponding reference compounds. On the whole, the redshifts and the reduced molecular orbital energy levels caused by bromine substituent decrease with the increase in the number of π electron in an aryl ring. The effects would be attributed to strong p‐π conjugation between p electron in the bromine substituent and π electrons in aryl rings. Therefore, this paper suggests a useful way for tuning optical absorption and molecular orbital energy levels of aryl compounds.     

一种基于遗传优化的BP神经网络的测光红移估计算法

除了星系的光谱红移之外,星系测光红移的估计也对研究宇宙大尺度结构及演变有着重要的研究意义。利用斯隆巡天项目最新发布的SDSS DR13的150 000个星系的测光及光谱数据,在红移值Z<0.8范围内,先使用SOM自组织神经网络对星系样本进行早型星系和晚型星系的聚类,然后用遗传算法优化后的BP神经网络对星系的测光红移进行估算。估算结果与作为标准的已知星系光谱红移进行比对,早型星系的红移估计最小均方误差约为0.001 3,晚型星系最小均方误差约为0.001 7。实验结果表明,遗传优化的BP算法在精度上优于BP神经网络算法,且效率上优于K近邻、核回归等传统测光红移估计算法。     

Exact recession velocity and cosmic redshift based on cosmological principle and Yang-Mills gravity

Based on the cosmological principle and quantum Yang-Mills gravity in the super-macroscopic limit, we obtain an exact recession velocity and cosmic redshift z, as measured in an inertial frame F ≡ F(t, x, y, z). For a matter-dominated universe, we have the effective cosmic metric tensor G_(μν)(t) =(B~2(t),-A~2(t),-A~2(t),-A~2(t)),A ∝ B ∝ t~(1/2), where t has the operational meaning of time in F frame. We assume a cosmic action S ≡ S cos involving Gμν(t) and derive the ‘Okubo equation' of motion, G μν(t)?μS ?νS-m2= 0, for a distant galaxy with mass m. This cos-√mic equation predicts an exact recession velocity, ■, where H = A˙(t)/A(t) and Co = B/A, as observed in the inertial frame F. For small velocities, we have the usual Hubble's law r≈ rH for recession velocities. Following the formulation of the accelerated Wu-Doppler effect, we investigate cosmic redshifts z as measured in F. It is natural to assume the massless Okubo equation, G μν(t)?μψe?νψe= 0, for light emitted from accelerated distant galaxies. Based on the principle of limiting continuation of physical laws, we obtain a transformation for covariant wave 4-vectors between and inertial and an accelerated frame, and predict a relationship for the exact recession velocity and cosmic redshift, z = [(1 + V_r)/(1-V_r~2)~(1/2)]-1, where Vr= r˙/Co 1, as observed in the inertial frame F. These predictions of the cosmic model are consistent with experiments for small velocities and should be further tested.     

Redshift drift constraints on f(T) gravity

We explore the impact of the Sandage−Loeb (SL) test on the precision of cosmological constraints for f(T) gravity theories. The SL test is an important supplement to current cosmological observations because it measures the redshift drift in the Lyman-α forest in the spectra of distant quasars, covering the “redshift desert” of 2≲z≲5. To avoid data inconsistency, we use the best-fit models based on current combined observational data as fiducial models to simulate 30 mock SL test data. We quantify the impact of these SL test data on parameter estimation for f(T) gravity theories. Two typical f(T) models are considered, the power-law model f(T)_PL and the exponential-form model f(T)_EXP. The results show that the SL test can effectively break the existing strong degeneracy between the present-day matter density Ω_m and the Hubble constant H₀ in other cosmological observations. For the considered f(T) models, a 30-year observation of the SL test can improve the constraint precision of Ω_m and H₀ enormously but cannot effectively improve the constraint precision of the model parameters.     

超短脉冲强激光与固体靶作用产生的高次谐波红移

用一维粒子模拟程序研究了超短脉冲强激光与超临界密度等离子体平板作用产生的高次谐波。分析了振荡镜面模型所不能解释的伴随高次谐波出现的频率红移现象。通常激光与固体靶作用中的高次谐波是由于激光从振荡靶面的反射产生的.除此之外，相对论光强的激光与固体靶作用还应考虑光压对靶的烧蚀推进作用，这时激光相当于从一个移动的振荡靶面反射，所以产生了带有红移的高次谐波. 关键词： 红移 超短脉冲强激光 高次谐波 粒子模拟     

Elliptical Solutions to the Standard Cosmology Model with Realistic Values of Matter Density

We have examined a solution to the FRW model of the Einstein and de Sitter Universe, often termed the standard model of cosmology, using wide values for the normalized cosmic constant (Ω_∧) and spacetime curvature (Ω _k ) with proposed values of normalized matter density. These solutions were evaluated using a combination of the third type of elliptical equations and were found to display critical points for redshift z, between 1 and 3, when Ω_∧ is positive. These critical points occur at values for normalized cosmic constant higher than those currently thought important, though we find this solution interesting because the Ω_∧ term may increase in dominance as the Universe evolves bringing this discontinuity into importance. We also find positive Ω_∧tends towards attractive at values of z which are commonly observed for distant galaxies.     

De Broglie Tired Light Model and the Reality of the Quantum Waves

In the early 1960s of the 20th century de Broglie was able to explain the cosmological observable red shift, without ad hoc assumptions. Starting from basic quantum considerations he developed his tired light model for the photon. This model explains in a single and beautiful causal way the cosmological redshift without need of assuming the Big Bang and consequently a beginning for the universe. Evidence coming from Earth sciences seems also to confirm these ideas and furthermore concrete proposal of laboratorial scale experiments that can test the model are reviewed.     

不同组分InxGa1-xAs(0≤x≤0.3)覆盖层对自组织InAs量子点的影响

研究了不同In组分的In_xGa_1-xAs(0≤x≤0.3)覆盖层对自组织InAs量子点的结构及发光特性的影响.透射电子显微镜和原子力显微镜表明,InAs量子点在InGaAs做盖层时所受应力较GaAs盖层时有所减小,并且x＝0.3时,InGaAs在InAs量子点上继续成岛.随x值的增大,量子点的光荧光峰红移,但随温度的变化发光峰峰位变化不明显.理论分析表明InAs量子点所受应力及其均匀性的变化分别是导致上述现象的主要原因. 关键词： 量子点 盖层 应力 红移     

The DWT power spectrum analysis of the large scale structure in the universe : Method and simulation tests

Based on the discrete wavelet transformation ( DWT), we present a pixelized method of estimating the power spectra of galaxy samples. With local properties of wavelet both in physical and wavenumber spaces, DWT power spectrum is equal to the corresponding band average of Fourier power spectrum. The DWT estimator is optimized in the sense that the spatial resolution is adaptive automatically to the perturbation wavelength to be studied. Under the assumption of ergodicity, the spatial average of local DWT fluctuation modes provides a fair estimation of the ensemble average. We test DWT spectra of four typical cold dark matter (CDM) structure formation models with numerical simulations. To consider the infections of various observation effects to the DWT spectra, we introduce irregular survey geometries, a given sampling rate, radial selection effects and redshift distortion effects into our mock samples. The numerical results show that, owing to its local properties, DWT spectrum is less affected by the sampling rate, survey geometry, and statistical ensemble fluctuations. With fast wavelet decomposition algorithm, DWT can be used to analyze large survey samples, which is of direct significance in precise measurement of the cosmological parameters from the galaxy redshift surveys of next generation.