Analysis of risk factors associated with pre-myopia among primary school students in the Mianyang Science City.

Objectives To find out the prevalence rate of pre-myopia among primary school students in the Mianyang Science City Area, analyze its related risk factors, and thus provide a reference for local authorities to formulate policies on the prevention and control of myopia for primary school students. Methods From September to October 2021, Cluster sampling was adopted by our research group to obtain the vision levels of primary school students employing a diopter test in the Science City Area. In addition, questionnaires were distributed to help us find the risk factors associated with pre-myopia. Through the statistical analysis, we identify the main risk factors for pre-myopia and propose appropriate interventions. Results The prevalence rate of pre-myopia among primary school students in the Science City Area was 45.27% (1020/2253), of which 43.82% were boys and 46.92% were girls, with no statistically significant difference in the prevalence rate of myopia between boys and girls (2 =2.171, P=0.141). The results of the linear trend test showed that the prevalence rate of pre-myopia tends to decrease with increasing age (Z=296.521, P=0.000). Logistic regression analysis demonstrated that the main risk factors for pre-myopia were having at least one parent with myopia, spending less than 2 hours a day outdoors, using the eyes continuously for more than 1 hour, looking at electronic screens for more than 2 hours, and having an improper reading and writing posture. Conclusion The Science City Area has a high prevalence rate of pre-myopia among primary school students. It is proposed that students, schools, families, and local authorities work together to increase the time spent outdoors, reduce digital screens and develop scientific use of eye habits.

Coronary Artery Tree Description and Lesion Evaluation (CatLet) score for functional evaluation of coronary stenosis: a comparison study with pressure wire fractional flow reserve.

Background: Pressure wire fractional flow reserve (FFR) and its derivatives, such as quantitative flow ratio (QFR), computational pressure flow-derived FFR (caFFR), coronary angiography-derived FFR (FFRangio), and computed tomography-derived FFR (FFRCT), have been validated for identifying functionally significant stenosis and guiding revascularization strategy. The limitations of using these methods include the side effects of hyperemia-induced agents, additional costs, and vulnerability to microvascular resistance. FFR is related both to the degree of a stenotic coronary artery and to its subtended myocardial territory. Coronary Artery Tree Description and Lesion Evaluation (CatLet) score (also known as Hexu) is a product of the degree of a stenosis and the weighting of the affected coronary artery (myocardial territory). Hence, we hypothesized that the CatLet score could predict hemodynamically significant coronary stenosis. Methods: We retrospectively enrolled consecutive patients with stable coronary artery disease. They attended Sichuan Science City Hospital with at least one lesion of 50-90% diameter stenosis in a coronary artery of 2 mm or larger. FFR measurement was obtained during invasive coronary angiography. The CatLet score was obtained by multiplying a fixed value of 2.0 (for non-occlusive lesions) and the weight of the affected coronary artery. The primary endpoint was the CatLet score's diagnostic accuracy in identifying hemodynamically significant coronary stenosis, with a pressure wire FFR of ≤0.80 being used as reference. Results: We analyzed the FFR and CatLet scores from 206 vessels in 175 patients with stable coronary disease and intermediate coronary lesions. The per-vessel analysis revealed an overall good correlation between the CatLet score and the FFR [r=-0.61; 95% confidence interval (95% CI): -0.69 to -0.52; P<0.01]. We also noted a significant CatLet score-FFR correlation for each of the left anterior descending artery (LAD), left circumflex (LCX), and right coronary artery (RCA). With a CatLet score ≥10 as a predictor of FFR ≤0.80, the overall diagnostic accuracy included a sensitivity of 78.80% (95% CI: 67.00-87.90%), a specificity of 85.00% (95% CI: 78.00-90.50%), a positive likelihood ratio of 5.25, a negative likelihood ratio of 0.25, and an area under the curve of 0.90 (95% CI: 0.85-0.94). Equivalent vessel-specific results were also achieved for each of the LAD, LCX, and RCA. Conclusions: The CatLet score, solely based on visual estimation of the results of coronary angiography, demonstrated good diagnostic performance with respect to myocardial ischemia. Its clinical values in guiding revascularization warrant further investigation.

Vibrational spectra of guaiacylglycerol-ß-guaiacyl ether: experiment and theory.

As an important inter-unit of lignin, guaiacylglycerol-ß-guaiacyl (GG) ether has been synthesized, and characterized using terahertz time-domain spectroscopy in the frequency range of 5-85 cm(-1). Seven absorption peaks have been observed. Among these peaks, the 49.8 cm(-1) and 57.6 cm(-1) vibrations are propose to be characteristic absorption peaks of GG ether. Raman spectra were also measured in the range of 50-3500 cm(-1). The vibrations of the two lowest energy forms, i.e., erythro 1r4s and threo 1s4s, were calculated using density functional theory at the B3LYP/6-311G∗∗ level and assigned according to potential energy distribution. In addition, the contents of erythro and threo forms in GG sample could be estimated by comparing the waveform similarities between theoretical and observed curves in the 33.0-80.0 cm(-1) range. Results showed that the observed curve of GG sample is a combination of erythro 1s4r and threo 1s4s. The four absorption vibrations below 33.0 cm(-1) could be assigned to phonon, inter-molecular modes and/or hydrogen bond vibrations. Terahertz spectra and Raman spectra, together with theoretical calculations, could be powerful methods for predicting contents of different isomers in sample.

[Terahertz spectroscopic inspection and analysis of xylitol and D-xylose].

In the present paper, THz spectra of xylitol and D-xylose are measured at room temperature in the frequency region of 0.3-2.6 THz. The results show that characteristic absorption peak of D-xylose was found at 1.67, 1.96 and 2.46 THz, and those of xylitol at 1.62, 1.87 and 2.51 THz. At the same time, density functional theory was applied to obtain the structure and vibration frequencies of the single molecules of two samples in THz region. The simulation results reveal that some of the absorption peaks result from the intra-molecular modes, while the others have to be attributed to intermolecular interaction or phonon modes.

[THz-ultraviolet spectra of KDP crystal].

THz time domain spectrum of KH2PO4 crystal in the range from 0.2 to 1.6 THz, the far-infrared spectrum in the range from 50-4000 cm(-1), and ultraviolet-visible-infrared spectrum in the range from 200-2000 nm were measured at the room temperature. The energy band gap Eg of KH2PO4 Crystal is 5.91 eV. There is a wide band of the phonon absorption in the KDP crystal. The values of the absorption coefficient are 35-80 cm(-1) in the range from 0.2 to 205.5 THz. The end of the low frequency of the optical phonon model is smaller than 0.2 THz. The highest frequency upsilonLO of the longitudinal optical phonon model LO is about 205.5 THz, and the force constant K of H-O ionic chemical bond stretch vibration from the omegaLO was calculated to be 13.13 N x cm(-1).

[Study on THz spectra of nicotinic acid, nicotinamide and nicotine].

The terahertz (THz) spectra of nicotinic acid, nicotinamide and nicotine were studied at room temperature. The time-domain THz spectra were measured. The frequency-domain spectra were obtained by fast Fourier transform (FFT). The spectral response and the dispersive relationship of refractive index in THz spectral range were obtained. The results show that the samples have obvious spectral response in THz spectral range except nicotine. The corresponding stimulated spectra were given by using density functional theory (DFT) method for both nicotinamide and nicotinic acid. The origin of the absorption peaks of nicotinic acid and nicotinamide was explored. It is thought that the absorption peak of nicotinic acid is caused by the torsion and wagging of the molecule, but the absorption peaks of nicotinamide (except 1.93 THz) are caused by intermolecular or phonon mode. It was shown that the molecule structure and vibrational modes of nicotinic acid and nicotinamide can be analyzed by the combination of simulation and experimental results.

[Chinese traditional medicine recognition by support vector machine (SVM) terahertz spectrum].

Identification is very important for the development of Chinese traditional medicines. In recent years, rapid progress in ultrafast laser technology provides a steady and available source for,terahertz pulses generation, which greatly promotes the development of THz spectroscopy and imaging technique. SVM is a method for recognition of two kinds of samples. Appling SVM to the identification of Chinese traditional medicines through THz spectrum is a new way. The experiment on three groups of Chinese traditional medicines (zhigancao and shengancao, nanchaihu and beichaihu, shandougen and beidougen) was studied. The THz frequency spectrum and absorptivity were obtained and used to construct the feature space of Chinese traditional medicines. Three kinds of SVM were build, which used three kinds of kernel functions. By comparison, a model of BP artificial neural network was constructed. The result of using three kinds of SVM and BP artificial neural network to identify the Chinese traditional medicines showed that both methods have good prediction ability, but obviously the effect of SVM is better than BP artificial neural network for small samples. Using SVM in terahertz spectrum is a efficacious way for classification of Chinese traditional medicines.

[Study on terahertz spectra of multi-walled carbon nanotubes].

In the present paper, the authors report the characterization of multiwalled carbon nanotube at terahertz (THz) frequency range using terahertz time-domain spectroscopy. The surface appearances and microanalysis of multiwalled carbon nanotubes were measured by scanning electron microscope in order to fully understand the unique features and applications of multiwalled carbon nanotube. The results show that the refractive indexes of the sample decrease with increasing frequency in the frequency range of 0.2 to 2 THz, while the absorption coefficients of the sample increase with increasing frequency. In addition, the curve of terahertz absorption coefficients can be fitted by a straight line with a slope of 1.92. From the results of scanning electron microscope, the ranges of inner diameter and outer diameters of the sample were from 5 to 15 nm and from 15 to 25 nm, respectively, and its length was in the order of micrometer. The results of microanalysis of its elemental composition showed that the content of element C was about 94% and the rest were O and Cl elements, which were impurity elements. Mathematical modes of terahertz absorption and refractive indexes in the frequency range of 0.2 to 2.0 THz were established after taking into account Taylor expansion and Maxwell's equations, and the calculation was in relatively good agreement with the observed values of the sample in general. The terahertz refractive indexes and absorption properties of multiwalled carbon nanotube were mainly attributed to the chemical compositions and molecular weight, and carbon nanotubes with different content of carbon could show different terahertz absorption spectra and disclose different unique functions.

[THz absorption spectra of several carbohydrate derivatives].

Intermolecular hydrogen bond vibrations may be observed in the THz range. Carbohydrates are important bio-molecules, and are the typical systems for the study of hydrogen bonds. Carbohydrate derivatives have critical biological functions, and there are extensive hydrogen bond networks in molecular system, therefore, they would have various bands in the THz region. The THz absorption spectra of several carbohydrate derivatives were measured using a THz apparatus at room temperature. The THz bands are as follows: 1.17, 1.35, 1.93 and 2.23 THz for isopropyl-beta-D-thioglucopyranoside; 1.93 THz for isopropyl-beta-D- thiogalactopyranoside; 1.87 THz for methyl-(tetra-O-acetyl-beta-D-galactopyranoside); 1.23, 1.70, 1.84 and 2. 23 THz for O-(2, 3, 4, 6-tetra-O-acetyl-beta-glucopyranosyl)-N-hydroxysuccinimide. The results indicate that different samples have various bands that originated from collective modes of the whole molecules and especially isomers can be distinguished, showing that THz method is sensitive to the molecular structures and spatial configurations and is a helpful complement of IR spectroscopy.