A concise synthesis of 2-chloro-3-amino-4-methylpyridine

An improved and commercially valuable process is developed for the scalable synthesis of 2-chloro-3-amino-4-methylpyridine (CAPIC), a key intermediate of Nevirapine. The synthesis was accomplished in four steps, featuring condensation starting from 4,4-dimethoxyl-2-butanone and cyanoacetamide with ammonium acetate and acetic acid as catalysts. The total yield of the process is 62.1%. The pure CAPIC sample was confirmed with FTIR, ¹H NMR, and ¹³C NMR spectra.     

A Green Method for Recycling 2‐Propanol from Water during Purification Process of Aqueous Nanocrystals

During traditional 2‐propanol‐based purification of aqueous nanocrystals (NCs), it is very difficult to recycle 2‐propanol from the aqueous solution, which brings great consumption of 2‐propanol during the purification process. A major contribution of this work is to provide a simple way to reduce the consumption via recycling of 2‐propanol during the purification process. The recycled 2‐propanol is available for precipitating NCs from aqueous solution in a new round of NC purification process. Due to the recycling of 2‐propanol, the great consumption of 2‐propanol can be avoided, which makes the purification process of aqueous NCs much greener and at a much lower cost.     

Developmental validation of the Yfiler Platinum PCR Amplification Kit for forensic genetic caseworks and databases

Y chromosome kits are successfully applied in cases where human biological material exists. With the development of genotyping ability, more Y chromosomal markers are needed for finer identification of male individuals and lineages. In this study, a developmental validation of a newly emerged Y chromosome kit that combines two different kinds of markers: 38 Y-STRs and 3 Y-indels are conducted. The results show that this kit has high sensitivity when there is a small amount of DNA (125 pg), more than one male (minor:major = 1:7), or a mixture of males and females (male:female = 125pg:1875pg), inhibited substances (800 μM hematin and more than 1600 ng/μL humic acid). The kit exhibits high precision level with a standard deviation of allele size no more than 0.14 nt. Locus DYS481 shows the largest stutter rate, with three stutters per true allele. Population samples are well identified (MP of 0.001106), and mutations can be observed in father–son pairs (46 mutations in 70 pairs, 10 in locus DYS627). Out of all the population samples, 13.2% belong to haplogroup M117-O2a2b1a1, with their ethnic group being Han Chinese. The results show that this kit can improve the performance of identifying male individuals, obtaining more unique haplotypes (increasing from 894 to 918 of 1000 male samples) and higher discrimination capacity (increasing from 0.942 to 0.955) in this study compared to previous widely used Yfiler Plus kit. Besides, it gives information about their paternal lineages in forensic genetic casework and genealogical database construction.     

A new graphical coding of DNA sequence and its similarity calculation

The DNA primary sequence is translated into “structure graph” based on classification of its four bases. Then the invariants, such as topological indices, are extracted from those graphic representations of DNA primary sequences, and used to calculate the similarities among the eleven species. From these similarities/dissimilarities the homologies can be revealed that they are in agreement with evolutionary relation satisfactorily.     

One-step synthesis of lamellar molybdate pillared hydrotalcite and its application for AZ31 Mg alloy protection

A novel anticorrosion pigment for AZ31 Mg alloy protection, molybdate pillared hydrotalcite (HT-MoO₄^2?), was successfully fabricated via a simple one-step process. The physicochemical properties of the samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectra, and inductively coupled plasma (ICP) method, respectively. The results indicated that the material showed typical characteristics of molybdate intercalated hydrotalcite. Additionally, it was found that the sample exhibited nano-sized lamellar morphology with the particle size of 35–60 nm. Moreover, the coating on AZ31 Mg alloy containing HT-MoO₄^2? pigment showed obviously higher corrosion protection performance in comparison with the strontium chromate (SC) pigment by Electrochemical impedance spectroscopy (EIS) measurements. The mechanism of corrosion protection was proposed to be that the HT-MoO₄^2? pigment in the coating would cause the pigment to undergo amphoteric ion exchange with aggressive NaCl solution, leading to the release of molybdate and Zn²⁺ inhibitors.     

Modified frames with block size 3

A modified (k, λ)‐frame of type g^u is a modified (k, λ)‐GDD whose blocks can be partitioned into holey parallel classes, each of which is with respect to some group. Modified frames can be used to construct some other resolvable designs such as resolvable group divisible designs and semiframes. In this article, we shall investigate the existence of modified frames with block size 3. © 2007 Wiley Periodicals, Inc. J Combin Designs 16: 351–363, 2008     

Misalignment Fault Prediction of Wind Turbines Based on Improved Artificial Fish Swarm Algorithm

A misalignment fault is a kind of potential fault in double-fed wind turbines. The reasonable and effective fault prediction models are used to predict its development trend before serious faults occur, which can take measures to repair in advance and reduce human and material losses. In this paper, the Least Squares Support Vector Machine optimized by the Improved Artificial Fish Swarm Algorithm is used to predict the misalignment index of the experiment platform. The mixed features of time domain, frequency domain, and time-frequency domain indexes of vibration or stator current signals are the inputs of the Least Squares Support Vector Machine. The kurtosis of the same signals is the output of the model, and the 3σ principle of the normal distribution is adopted to set the warning line of misalignment fault. Compared with other optimization algorithms, the experimental results show that the proposed prediction model can predict the development trend of the misalignment index with the least prediction error.     

翠绿亚胺聚合物高压下芳环扭角和能隙的缩减

利用改进的Ginder-Epstein模型计算了翠绿亚胺聚合物在参数V4,0取值于1.8～35.8 eV的自洽变分基态,并通过芳环扭角的变化来估算聚合物压强,给出了V4,0,芳环扭角及能隙与理论压强之间的最小二乘拟合.结果表明随此参数的增大,芳环扭角和能隙都缩减而理论压强升高.当理论压强由零压增至3.0 GPa左右时,能隙先快后慢从2.0 eV减小至最小值0.87 eV.这理论与该聚合物的高压电导测试结果一致.