Investigation of Obstacles with Interactive Elements on the Flow in SiC Three-Dimensional Printing.

A single screw extruder is used in this study to efficiently transport SiC slurry in direct ink writing (DIW) technology. The deposits caused by low viscosity and the agglomerations resulting from the nonuniform mixing form the obstacles in the channel, which affect the normal flow of the slurry, theoretical outlet velocity, and interaction with other printing parameters. Therefore, it is necessary to study the effect mechanism of the obstacles on the flow. The obstacles are always irregular, which makes it difficult to directly analyze them. Irregular geometries are always composed of linear and/or arcuate elements; therefore, the obstacles can be simplified into regular geometries. In the present work, interactive elements, including line-line, line-arc, arc-arc situations are analyzed. Then, an improved multiple relaxation time lattice Boltzmann method (MRT LBM) with a pseudo external force is proposed for the flow analysis. The improved MRT LBM is combined with rheological test data to investigate cases with interactive elements, and the results are applied to reveal the general mechanism. The results show that the positions are common influencing factors, which affect the streamlines, outflow directions, and outlet velocity distributions. In addition, in different situations, different factors are considered to affect SiC slurry flow. It is obvious that the existed obstacles inevitably change the theoretical flow direction and outlet velocity, which has a synergistic effect on the printing parameters. It is necessary to understand the effect mechanism of the obstacles on the flow.

Use of liquid chromatography-tandem mass spectrometry for determination of higenamine in urine following oral administration of traditional Chinese medicine.

Since higenamine (HG) was first included in the World Anti-doping Agency (WADA) 2017 Prohibited List, an increasing number of plants have been found to contain this ingredient. As a result, doctors are hesitant to prescribe traditional Chinese medicine (TCM) to athletes. Thus, it is very important to assess the risks of doping violations due to HG following the oral administration of TCM. We determined the drug concentration-time curves for HG in urine by liquid chromatography-tandem mass spectrometry (LC-MS/MS) after single or multiple administrations of lotus seed powder on volunteers, the single dose was equivalent to 750 µg of HG, and the multiple doses were equivalent to 90 µg of HG each, 3 times daily for 5 consecutive days. For the single-dose group, the HG could be detected in urine 0.5 h after administration and reached a maximum concentration of 16.5 ng/mL 1 h after administration. For the multiple-dose group, the HG concentrations in urine showed two peaks at 29 and 77 h post-administration with 22.6 and 23.1 ng/mL, respectively. At the dosage used in this study, the maximum concentration of HG in some urine samples exceeded the WADA limit of 10.0 ng/mL; the risk was still very high, so athletes must avoid this amount of HG when using TCM. In addition, our study provided further data supporting the presence of sulfonated metabolites of HG in urine samples.

Nonsurgical spinal decompression system traction combined with electroacupuncture in the treatment of multi-segmental cervical disc herniation: A case report.

RATIONALE: With the spread of computers and mobile phones, cervical spondylosis has become a common occupational disease in clinics, which seriously affects the quality of life of patients. We used a nonsurgical spinal decompression system (SDS) combined with physical therapy electroacupuncture (EA) to treat a case of mixed cervical spondylosis caused by multi-level cervical disc herniation, and we achieved satisfactory results. PATIENT CONCERNS: A 44-year-old Caucasian Asian woman presented with neck pain and numbness on the left side of the limb. MRI showed the patient's C3-C7 segment cervical disc herniation, and the flexion arch of the cervical spine was reversed. DIAGNOSIS: The patient was diagnosed with a mixed cervical spondylosis. INTERVENTIONS: The patient received a month of physical therapy (SDS traction combined with EA). OUTCOMES: Before and after treatment: VAS score of neck pain decreased from 8 to 0; Cervical spine mobility returned to normal; The grip strength of left hand increased from 7.5 kg to 19.2 kg; Cervical curvature index changed from -16.04% to -3.50%; the physiological curvature of the cervical spine was significantly restored. There was no dizziness or neck discomfort at 6 month and 1 year follow-up. LESSONS SUBSETIONS: SDS traction combined with EA is effective for the treatment of cervical disc herniation and can help restore and rebuild the biomechanical balance of the cervical spine.

Nature-Inspired Structures Applied in Heat Transfer Enhancement and Drag Reduction.

Heat exchangers are general equipment for energy exchange in the industrial field. Enhancing the heat transfer of a heat exchanger with low pump energy consumption is beneficial to the maximum utilization of energy. The optimization design for enhanced heat transfer structure is an effective method to improve the heat transfer coefficient. Present research shows that the biomimetic structures applied in different equipment could enhance heat transfer and reduce flow resistance significantly. Firstly, six biomimetic structures including the fractal-tree-like structure, conical column structure, hybrid wetting structure, scale structure, concave-convex structure and superhydrophobic micro-nano structure were summarized in this paper. The biomimetic structure characteristics and heat transfer enhancement and drag reduction mechanisms were analyzed. Secondly, four processing methods including photolithography, nanoimprinting, femtosecond laser processing and 3D printing were introduced as the reference of biomimetic structure machining. Finally, according to the systemic summary of the research review, the prospect of biomimetic heat transfer structure optimization was proposed.

Spatiotemporal distributions of ambient SO2 across China based on satellite retrievals and ground observations: Substantial decrease in human exposure during 2013-2016.

Multiyear spatiotemporal distributions of daily ambient sulfur dioxide (SO2) are essential for evaluating management effectiveness and assessing human health risk. In this study, we estimate the daily SO2 levels across China on 0.1o grid from 2013 to 2016 by assimilating satellite- and ground-based SO2 observations using the random-forest spatiotemporal kriging (RF-STK) model. The cross-validation R2 is 0.64 and 0.81 for predicting the daily and multiyear averages, respectively. The multiyear population-weighted average of SO2 for China is 28.1 ±â€¯14.0 µg/m3, and the severest SO2 pollution occurs in the northern China (45.1 ±â€¯14.7 µg/m3). The SO2 concentration shows a strong seasonality, i.e., highest in winter (41.6 ±â€¯26.4 µg/m3) and lowest in summer (19.6 ±â€¯8.3 µg/m3). During 2013-2016, the annual SO2 decreases from 34.4 ±â€¯18.2 to 22.7 ±â€¯11.1 µg/m3, and the population% exposed for more than 100 nonattainment days (SO2 > 20 µg/m3) drops from 86% to 48%. While the seasonality of SO2 is mainly determined by the meteorological variation, the substantial decrease attributes to the reduced emissions such as from coal consumption. The effectiveness of SO2 emission reduction varies widely in different prefectures of China. In Shandong province, the SO2 concentration decreases by -45% while the coal consumption increases by 9%. In Shanxi province, the SO2 concentration decreases by -15% while the coal consumption decreases by -3%. The contrasting effectiveness between these two provinces is associated with the much fewer waste gas disposal facilities in Shanxi than Shandong. Stricter regulation is required to further lower the SO2 concentration in order to protect the public health, especially in the northern China.

ß-Glucan synthase gene overexpression and ß-glucans overproduction in Pleurotus ostreatus using promoter swapping.

Mushroom ß-glucans are potent immunological stimulators in medicine, but their productivities are very low. In this study, we successfully improved its production by promoter engineering in Pleurotus ostreatus. The promoter for ß-1,3-glucan synthase gene (GLS) was replaced by the promoter of glyceraldehyde-3-phosphate dehydrogenase gene of Aspergillus nidulans. The homologous recombination fragment for swapping GLS promoter comprised five segments, which were fused by two rounds of combined touchdown PCR and overlap extension PCR (TD-OE PCR), and was introduced into P. ostreatus through PEG/CaCl2-mediated protoplast transformation. The transformants exhibited one to three fold higher transcription of GLS gene and produced 32% to 131% higher yield of ß-glucans than the wild type. The polysaccharide yields had a significant positive correlation to the GLS gene expression. The infrared spectra of the polysaccharides all displayed the typical absorption peaks of ß-glucans. This is the first report of successful swapping of promoters in filamentous fungi.