Dynamic modeling and analysis of hybrid driven multi-link press mechanism considering non-uniform wear clearance of revolute joints

Meccanica - The multi-link press mechanism is developing in the direction of high speed and high precision. However, the non-uniform wear of joint clearance seriously affects the output motion...     

On partitions classified by smallest missing part

The Ramanujan Journal - In this paper, we study partitions classified by its smallest missing part. Our main theorem is an inequality related to the parity of the smallest missing part of...     

Determination of Trimethylamine N-oxide and Betaine in Serum and Food by Targeted Metabonomics

Trimethylamine N-oxide (TMAO), as a gut-derived metabolite, has been found to be associated with enhanced risk for atherosclerosis and cardiovascular disease. We presented a method for targeted profiling of TMAO and betaine in serum and food samples based on a combination of one-step sample pretreatment and proton nuclear magnetic resonance spectroscopy. The key step included a processing of sample preparation using a selective solid-phase extraction column for retention of basic metabolites. Proton signals at δ 3.29 and δ 3.28 were employed to quantify TMAO and betaine, respectively. The developed method was examined with acceptable linear relationship, precision, stability, repeatability, and accuracy. It was successfully applied to detect serum levels of TMAO and betaine in TMAO-fed mice and high-fructose-fed rats and also used to determine the contents of TMAO and betaine in several kinds of food, such as fish, pork, milk, and egg yolk.     

超高效液相色谱法测定湿巾中7种防腐剂

建立超高效液相色谱法测定湿巾中7种防腐剂的检测方法。样品采用甲醇超声提取,色谱柱采用Waters ACQUITY UPLC BEH C_(18)柱(50 mm×2.1 mm,1.7μm),流动相为甲醇–乙酸水溶液(pH 3.3)梯度洗脱,初始流量为0.8 m L/min,用PDA检测器检测,检测波长分别为255,270,310 nm。以3倍空白噪音计,2-溴-2-硝基丙烷-1,3-二醇,苯酚,苯甲醇,苯氧乙醇,苯甲酸,山梨酸,脱氢乙酸的检出限分别为60.0,0.5,20.0,8.0,5.0,0.2,0.5 mg/kg;方法加标回收率为100.9%~109.3%;测定结果的相对标准偏差为0.2%~1.9%(n=6)。结果表明该方法处理简单,分离效果好,速度快,能快速准确测定湿巾中7种防腐剂。     

Self-modulated highly chemoselective direct-reductive-amination (DRA) of benzaldehydes straightforward to N-monosubstituted benzylamine hydrochlorides

An unprecedented efficient and chemoselective DRA of benzaldehydes and primary amines was developed to directly yield N-monosubstituted benzylamine hydrochlorides as single products in practically quantitative yields. The method was characterized by simply adding a few milliliters of CHCl₃ in the conventional Pd-C catalytic hydrogenation system at atmospheric pressure and room temperature. A self-modulated system and a four-stage cyclic pathway were proposed.     

Determination of some refractory elements and Pb by fluorination assisted electrothermal vaporization inductively coupled plasma mass spectrometry with platform and wall vaporization

Platform and wall vaporization for electrothermal vaporization (ETV)-inductively coupled plasma mass spectrometry (ICP-MS) determination of some refractory elements (Ti, V, Cr, Mo, La and Zr) and Pb were comparatively studied with the use of poly (tetrafluoroethylene) (PTFE) as fluorinating reagent. The factors affecting the vaporization behaviors of the target analytes in the platform and tube wall vaporization including vaporization temperature and time, pyrolytic temperature and time were studied in detail, and the flow rates of carrier gas/auxiliary carrier gas, were carefully optimized. Under the optimal conditions, the signal profiles, signal intensity, interferences of coexisting ions and analytical reproducibility for wall and platform vaporization ETV-ICP-MS were compared. It was found that both wall and platform vaporization could give very similar detection limits, but the platform vaporization provided higher signal intensity and better precision for some refractory elements and Pb than the wall vaporization. Especially for La, the signal intensity obtained by platform vaporization was 3 times higher than that obtained by wall vaporization. For platform vaporization ETV-ICP-MS, the limits of detection (LODs) of 0.001 μg L⁻¹ (La) ~ 0.09 μg L^− 1 (Ti) with the relative standard deviations (RSDs) of 1.5% (Pb) ~ 15.5% (Zr) were obtained. While for wall vaporization ETV-ICP-MS, LODs of 0.005 μg L^− 1 (La) ~ 0.4 μg L^− 1 (Pb) with RSDs of 3.2% (Mo) ~ 12.8% (Zr) were obtained. Both platform and tube wall vaporization techniques have been used for slurry sampling fluorination assisted ETV-ICP-MS direct determination of Ti, V, Cr, Mo, La, Zr and Pb in certified reference materials of NIES No. 8 vehicle exhaust particulates and GBW07401 soil, and the analytical results obtained are in good agreement with the certified values.     

Julia sets of permutable Holomorphic maps

Let f and g be two permutable transcendental holomorphic maps in the plane. We shall discuss the dynamical properties of f, g and f o g and prove, among other things, that if either f has no wandering domains or f is of bounded type, then the Julia sets of f and f(g) coincide. Dedicated to Professor Sheng GONG on the occasion of his 75th birthday     

The asymptotic probability distribution of the relative distance of additive quantum codes

For given information rate R, it is proved as n tends to infinite, that almost all additive ?n,n⋅R? quantum codes (pure and impure) are the codes with their relative distance tending to h⁻¹(1−R), where is an entropy function.