Quantitative composite testing model based on measurement uncertainty and its application for the detection of phthalate esters

To improve the quantitative detection efficiency of chemical analysis and reduce the detection cost, the sample pass rate was estimated and mathematical statistics were used to calculate the optimal group size (Kopt) of the composite testing to save on the maximum workload. A quantitative composite testing model was developed based on chemical analysis measurement uncertainty. Using this model, the maximum allowable number of composited samples (Kmax) is first calculated using parameters of regulated limits (L), limit of quantification (LOQ), and method measured uncertainty (Urel) to ensure that the sensitivity of the composite testing can meet the limit requirements. Finally, the appropriate composite group size (Ka) can be obtained by creating a balance between Kopt, Kmax, and the practical information used for that particular test. Furthermore, based on a constructed model, a practical quantitative composite testing method of 3–10 samples was established for the routine detection of toy phthalates (PAEs). The experimental results showed that the quantitative limits of 7 PAEs were 9.1–41.8 mg/kg, the relative expansion uncertainties were 16.6%–23.2%, and the recovery rates were 91.0%–112.3%, with a relative deviation of less than 10%. All these meet international PAEs standards. Compared with the traditional individual and qualitative composite testing, this model will not decrease the detection sensitivity, but can save up to 17.9%–80.4% of the workload when it is employed in toy PAEs testing with the pass rate of 80%–99%. This quantitative composite testing method will be implemented in the coming revision of ISO 8124-6 toy PAEs standards

Cavity ringdown laser absorption spectroscopy of free radicals

abstracttocpublished_or_final_versionChemistryDoctoralDoctor of Philosoph

MEASUREMENT OF THE ELECTRIC DIPOLE MOMENT AND MAGNETIC g-FACTOR IN NEODYMIUM MONOXIDE (NdO)

Author Institution: Centre for Lasers Atomic and Molecular Sciences (CLAMS) and Physics Department, University of New Brunswick, Fredericton, NB Canada E3B 5A3; Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287The diatomic oxides of the lanthanides and actinides have many low-lying electronic states due to the presence of open f and d orbitals on the metal. The magnetic and electric tuning of the fine structure is an effective means of identifying the dominant configuration of a particular electronic state. Here we report on the first high-resolution molecular beam measurements of the Stark and Zeeman effects in electronic transitions of neodymium monoxide, NdO. Numerous branch features in the previously detected [16.73] ($\Omega$=3) - $X$($\Omega$=4) electronic transition were recorded at near natural linewidth limit (FWHM $<$ 35MHz) field free and in the presence of tunable static magnetic (Zeeman effect) and electric (Stark effect) fields. The Stark and Zeeman splittings and shifts were used to extract values for the magnitudes of the permanent electric dipole moments and magnetic g-factors respectively of the two electronic states. The results are compared with those that we reported last year for uranium monoxide, UO} {\textbf{125}}, 204314/1-20431/11, (2006).}, which is the actinide analogue of NdO

Prediction of Financial Time Series Based on LSTM Using Wavelet Transform and Singular Spectrum Analysis

In order to further overcome the difficulties of the existing models in dealing with the nonstationary and nonlinear characteristics of high-frequency financial time series data, especially their weak generalization ability, this paper proposes an ensemble method based on data denoising methods, including the wavelet transform (WT) and singular spectrum analysis (SSA), and long-term short-term memory neural network (LSTM) to build a data prediction model. The financial time series is decomposed and reconstructed by WT and SSA to denoise. Under the condition of denoising, the smooth sequence with effective information is reconstructed. The smoothing sequence is introduced into LSTM and the predicted value is obtained. With the Dow Jones industrial average index (DJIA) as the research object, the closing price of the DJIA every five minutes is divided into short term (1 hour), medium term (3 hours), and long term (6 hours), respectively. Based on root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE), and absolute percentage error standard deviation (SDAPE), the experimental results show that in the short term, medium term, and long term, data denoising can greatly improve the stability of the prediction and can effectively improve the generalization ability of LSTM prediction model. As WT and SSA can extract useful information from the original sequence and avoid overfitting, the hybrid model can better grasp the sequence pattern of the closing price of the DJIA

CAVITY RING-DOWN LASER ABSORPTION SPECTROSCOPY OF IrC

Author Institution: Department of Chemistry, The University of Hong KongThe absorption spectrum of IrC at wavelength between 445-500 nm has been investigated using the technique of laser vaporization/reaction with free-jet expansion and cavity ring-down laser absorption (CRLA) spectroscopy. IrC molecule was produced by reacting laser-ablated iridium atoms with methane seeded in argon. This wavelength region covers the (0,0), (1,0) and (2,0) bands of the $L ^{2}\Phi_{7/2} - X ^{2}\Delta_{5/2}$ transition. Analysis of the spectra gives refined band origins, vibrational and rotational constants for the $L ^{2}\Phi_{7/2}$ level

Silver-Catalyzed Reaction of Enynals with Alkenes: A Tandem 1,3‑Dipolar Cycloaddition/Cyclopropanation

A silver-catalyzed reaction of enynals with alkenes to synthesize a series of polycyclic compounds has been developed. The reaction occurred smoothly using enynals with electron-deficient alkynes or terminal alkynes as substrates. The reaction was proposed to proceed through a tandem 1,3-dipolar cycloaddition/cyclopropanation process. The preliminary investigations of the asymmetric catalytic version revealed that the biphosphine ligand could be used as the potential efficient chiral ligand