Search

High-purity quartz is an emerging strategic material that has been extensively used in the semiconductor and photovoltaic fields. Taking vein quartz from southern Anhui Province as an example, raw materials were processed by ultrasonic scrubbing-desliming, magnetic separation, flotation, high-temperature calcination, water quenching, hot-press acid leaching, and deionized water cleaning to prepare high-purity quartz sand. At the same time, the microscopic structure, inclusions, phase, mineral morphology, water content in inclusions, and trace impurities of the gangue samples were analyzed using an optical microscope, a laser Raman spectrometer, an X-ray diffractometer, a scanning electron microscope, an infrared spectrum analyzer, and an inductively coupled plasma mass spectrometer. The results showed that feldspar and muscovite were the main impurities. After purification, the total amount of 13 impurities in quartz sand was reduced to 28.66 μg/g, and the contents of the main impurity elements Al, Na, and Fe were 12.81 μg/g, 12.80 μg/g, and 0.52 μg/g, respectively. The mass fraction of SiO2 increased from 99.06% to 99.9972%. This shows that flotation, high-temperature calcination, and hot-pressing acid leaching are the keys to obtaining high-purity quartz sand. Fluoride-free flotation with the new collector XK02 can effectively realize the deep separation of quartz and mineral impurities. High-temperature calcination can form more cracks on the surface of quartz sand particles, and the mixed acid enters the open crack channels to effectively remove impurities from the inclusions. This method provides technical support for the preparation of high-purity quartz sand with high value and for the efficient utilization of quartz ore. [ABSTRACT FROM AUTHOR]

As an independent characteristic of electromagnetic radiation, the polarization of light is sensitive to the scattering and absorption characteristics of the mineral particles. The combination of polarization and infrared absorption spectroscopy is conducive to rapidly and accurately detecting the SiO2 content of metallurgical sandstone deposits. In this study, the 8–14 μm polarized infrared absorption spectra and the grade of the sandstone ore samples were used to analyse the spectral characteristics of the sandstone powder samples. Principal component analysis (PCA) and the successive projection algorithm (SPA) were used to reduce the dimension of the original data, first-order derivative, reciprocal logarithm, and multivariate scattering correction (MSC) data. Then, generalized regression neural network (GRNN), partial least squares regression (PLSR), and convolutional neural network (CNN) were employed to establish a hyperspectral prediction model of SiO2 grade. The results show that the quantitative model by the PCA-CNN algorithm has the better prediction precision for the reciprocal logarithm data, with a coefficient of determination (R2), root mean square error (RMSE), and ratio of performance to interquartile range (RPIQ) of 0.907, 0.023, and 5.11, respectively. This method indicates that the polarized infrared absorption spectra and the PCA-CNN model can provide a more robust and significant spectral interpretation than single infrared spectra, and it is expected to be applied to any high-purity quartz deposit type for in situ and rapid analysis. [ABSTRACT FROM AUTHOR]

Objective To investigate the clinical value of high-flow nasal cannula oxygen therapy(HFNC) in patients with severe coronavirus disease 2019 (COVID-19) . Methods Adult patients with severe COVID-19 who were treated with HFNC in Guangzhou Eighth People's Hospital from January to February 2020 were selected. The clinical data, respiratory and circulatory parameters and lung ultrasound score (LUS) were collected to analyze the therapeutic characteristics of HFNC. Patients were divided into HFNC success group and HFNC failure group according to the success or failure of HFNC, breathing, circulation parameters, and LUS were compared in pre-treatment and 2, 48, 72 hours after treatment and before stopping HFNC or changing to invasive breathing. Results 41 patients with severe COVID-19 were treated with HFNC, 29 males and 12 females, the age was 33 -84 years old, the median age was 59.93 years old, the mean time of HFNC treatment was 6.7 days. Treatment failed in 14 patients: After treatment with HFNC, 27 cases (65.85%) showed significant improvement in oxygenation, respiratory rate and heart rate, avoiding invasive endotracheal intubation, and successfully replacing the machine to the nasal catheter with low-flow oxygen inhalation. Acute physiological and chronic health conditions(APACHE) H score [(19.86±6.70) points] in the failure group was higher than that [(7.82±3.49) points] in the success group; and PaO2, SaO2, SPO2 and PaO2/FIO2 in the success group were significantly higher than those in the failure group; HFNC treatment for 48 h: RR,HR and PaO2/ FIO2 did not improve but gradually deteriorated in the failure group (P<0.05) . Before stopping HFNC: PaO2, SaO2, Lus, PaO2 / FIO2 in the failure group were significantly worse than those before HFNC (P<0.01) .Conclusion HFNC can be used as inhalation support for patients with severe COVID-19. During the course of treatment, the relevant parameters of patients should be closely observed, especially the oxygenation index, pulse and breathing rate of patients should be paid attention to when HFNC is treated for 48 hours, invasive mechanical ventilation should be changed as soon as possible. [ABSTRACT FROM AUTHOR]

Objective: To investigate the correlation of apolipoprotein AI (ApoAI), ApoB, ApoB/ApoAI and the severity of brain white matter lesions (WML)., Methods: A total of 648 patients with WML confirmed by brain magnetic resonance imaging (MRI) were divided into mild WML group ( n =386) and moderate to severe WML group ( n =262) according to evaluations with the Fazekas scale. The demographic data, blood biochemical parameters and the levels of ApoAI, ApoB and ApoB/AI ratio were compared between the two groups to identify the risk factors of moderate to severe WML., Results: Univariate analysis showed that age, gender, hypertension, diabetes, coronary heart disease, previous stroke, homocysteine, HDL-C, ApoAI, and ApoB/AI ratio all differed significantly between the two groups ( P < 0.05), but ApoB levels were similar between them ( P > 0.05). Multivariate logistic regression analysis revealed that with ApoAI and ApoB/AI ratio as the continuous variables, after adjustment for the compounding factors, ApoB/AI ratio was an independent risk factor (OR=11.456, 95% CI : 3.622-36.229, P < 0.001) and ApoAI was an independent protective factor for moderate to severe WML (OR=0.068, 95% CI : 0.018-0.262, P < 0.001). With the upper quartiles of ApoAI level (1.38 g/L) and ApoB/AI ratio (0.58) as their respective cutoff values, patients with a high ApoAI level and a low ApoB/AI ratio were found to have the lowest incidence of moderate to severe WML ( P < 0.001)., Conclusions: An increased ApoB/AI ratio is an independent risk factor and an increased ApoAI level is an independent protective factor for moderate to severe WML.

Objective: To study the inducible nitric oxide synthase (iNOS) mRNA and protein expression in rat purified retinal ganglion cells (RGCs) that cultured under different pressures., Methods: (1) To culture RGCs that from Sprague Dawley (SD) neonatal rats (postnatal 1 - 5 days) on two planes in assimilative culture solution, RGCs were purified by Thy1.1 with sheep anti rat FITC monoclonal antibody. (2) RGCs were cultured under pressures of 0, 20, 40, 60 and 80 mm Hg, respectively. The changes of iNOS mRNA and protein in RGCs under different pressures were demonstrated qualitatively and quantitatively by in situ hybridization, RT-PCR and Western blot., Results: After cultured for 12 and 24 hours in vitro, the purification rate of RGCs in the experiment reached 98%. The expression of iNOS mRNA and protein in RGCs became higher and higher as the pressure was increased. There were no iNOS mRNA and protein expression in the control group (0 mm Hg) and weak expression in 20 mm Hg group (P < 0.05). 40, 60 and 80 mm Hg groups had a very significant difference from the control group, respectively (P < 0.01)., Conclusion: Pressure can evoke the expression of nitric oxide synthase mRNA and protein in purified retinal ganglion cells in vitro, thus the nitric oxide can be one of the causes of RGC damage, that may induce or aggravate glaucoma.

Objective: To investigate the effect of pressure on the expression of cell cycle and apoptosis related gene bcl-2 and bax mRNA by bovine trabecular meshwork cells., Method: Twenty mm Hg, 40 mm Hg, 60 mm Hg and 80 mm Hg(1 mm Hg = 0.133 kPa) pressure were given to the cultured trabecular meshwork cells respectively in the treatment groups. No pressure was given in the control groups. Each pressure sustained for 24 and 48 hours. Proliferation index, apoptosis index, bcl-2 and bax mRNA expression of trabecular meshwork cells were detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling, flow cytometry and in situ hybridization., Results: In 24 hour groups, there were no significant differences between the apoptosis index of control group and pressure /= 60 mm Hg. In 48 hour groups, apoptosis index, proliferative index and bax mRNA expression had significant differences from that of the control groups when pressure was >/= 40 mm Hg., Conclusion: Pressure >/= 40 mm Hg sustaining for a period of time can suppress trabecular meshwork cell proliferation and induce apoptosis through influencing bcl-2 family members.

The effects of different doses of nitric oxide (NO) on the proliferation and apoptosis of the cultured bovine trabecular meshwork (TM) cells were studied. L-arginine and NG-nitro-L-arginine methyl (L-NAME) were incubated with TM cells for 48 h. In the control group, no medicine was given. In the experimental groups, concentrations of L-arginine and L-NAME were 1 x 10(-7) mol/L, 1 x 10(-6) mol/L, 1 x 10(-5) mol/L, 1 x 10(-4) mol/L, 1 x 10(-3) mol/L and 1 x 10(-2) mol/L, respectively. NO2- in supernate, the proliferation and apoptosis of TM cells and mRNA expression of bcl-2 and bax were measured by Griess reagent, terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL), MTT assay and in situ hybridization, respectively. The results showed that L-arginine with concentration > or = 1 x 10(-4) mol/L could induce apoptosis of the TM cells and inhibit the proliferation of TM cells through increasing the NO levels, down-regulating bcl-2 mRNA expression and up-regulating bax mRNA expression; L-NAME with concentration > or = 1 x 10(-5) mol/L could induce the proliferation of the TM cells through suppressing the production of NO. It was concluded that NO in high level could induce apoptosis of the TM cells and suppress the proliferation of the TM cells.