Search

COVID‐19 has developed into a worldwide pandemic; early identification of severe illness is critical for controlling it and improving the prognosis of patients with limited medical resources. The present study aimed to analyze the characteristics of severe COVID‐19 and identify biomarkers for differential diagnosis and prognosis prediction. In total, 27 consecutive patients with COVID‐19 and 75 patients with flu were retrospectively enrolled. Clinical parameters were collected from electronic medical records. The disease course was divided into four stages: initial, progression, peak, and recovery stages, according to computed tomography (CT) progress. to mild COVID‐19, the lymphocytes in the severe COVID‐19 progressively decreased at the progression and the peak stages, but rebound in the recovery stage. The levels of C‐reactive protein (CRP) in the severe group at the initial and progression stages were higher than those in the mild group. Correlation analysis showed that CRP (R = .62; P, Highlights Compared with COVID’19, Patients with flu had higher WBC and granulocyte. Lymphocyte progressively decreased in the progress of COVID’19. CRP level associated with CT scores and disease development of COVID’19. CRP increased at the initial stage of severe COVID’19, prior to CT findings. CRP showed good performance in prediction of severe COVID’19.

It has always been a critical task to understand gear dynamics for gear design and condition monitoring. Many gear models have been proposed to simulate gear meshing dynamics. However, most of the theoretical models are based on simplified gear structure and may contain approximation errors. Direct measuring of gear strain is important for gear design validation, load analysis, reliability assessment, gear condition monitoring, etc. Most of the existing studies of tooth strain measurements are performed under static load condition. In this paper, we investigate new measuring techniques using fiber Bragg grating sensor and piezoelectric strain for gear dynamic strain measurement. We conduct gear dynamic strain measurement under both normal and pitted conditions to evaluate the strain transition process and pitting effect. The experiments are performed on an industrial gearbox with relatively small module gears. Multiple combinations of speed and load conditions are tested and the results are discussed and analyzed. We analyze multiple factors that affect the tooth root stress, including speed, load, extended tooth meshing, etc. It is found that under low operation speed range, the tooth root strain is mainly determined by the torque, while in the medium to high speed range, the tooth root strain is jointly affected by speed and torque. Extended tooth contact is shown in the measurement results with strong evidence. It conforms to earlier founding that the transmission error and dynamic load factor are overestimated for spur gear under heavy load. We also evaluate the change in dynamic strain caused by pitted tooth surface. It is shown that pitting faults lead to decreased bending strain on the tooth, especially in single-tooth contact zone, which represents a loss in torque and possibly reduced mesh stiffness. Numerical simulations are also provided to make comparisons and help to interpret the experimental results.

Utilizing optical Fiber Bragg Grating's (FBG) characteristic of transmission optic signals in non-contact way, the measure method of the twisted, variable cross-section, variable thickness, rotating rectangular blade's local strain has been presented. Firstly, by using the finite element method to obtain the rotating blade's natural frequency, modal shape and strain modal shape, the mounting location of the FBG on the rotating blade is determined; secondly, using optical fiber non-contact transmission device, the rotating blade's dynamic strain in different locations can be measured by FBG. In this paper, the author only analyzed the frequency, amplitude and the dynamic stiffening phenomenon of dynamic strain at one point in rotating state. Finally, the author points out that this method can effectively measure rotating blade's dynamic strain and dynamic response, by result analysis, rotatating blade worth further researching.

Strain measurement and vibration analysis of a rotating blade are critical for the progress in improvements of the performance of machines. Since traditional sensors and measurement methods have difficulty measuring the rotor blade’s dynamic strain and vibration, the search for new measurement methods has become an urgent task in rotor machine monitoring and diagnosis. This paper presents a new method based on Fiber Briggs Gratings (FBG) for the measurement of strain and estimation of vibrations in a rotating cantilever. The method is based on the fact that the vibration displacement can be expressed in terms of an infinite number of vibration modes and be related to the dynamic strains through strain-displacement relationship. By placing multiple sets of FBG and utilizing an optic coupler, the rotating cantilever beam’s dynamic strain can be measured and vibration can be estimated at the same time. From the results, it can be concluded that this new monitoring method is applicable to the rotating blade.

Telomerase is closely related to tumor, and hTERT is the rate-limiting factor for telomerase activity. The transcription and expression of hTERT is determined by hTERT promoter, which has the ability of anchoring telomerase positive cells. RNA interference (RNAi) has been potentially used in the functional genomics and gene therapy recently. However, the limitations of RNAi uncertain interference and safety hamper its wide applications. To overcome these limitations, we constructed shRNA vectors harboring either U6 promoter or chimera hTERT/U6 promoter aiming at EGFP and hTERT genes (shRNA-EGFP-U6, shRNA-EGFP-hTERT/U6, shRNA-hTERT-U6 and shRNA-hTERT-hTERT/U6), to suppress the expression of GFP and hTERT in telomerase negative human normal fibroblast HELF cells and telomerase positive human hepatocarcinoma SMMC-7721 and HepG2 cells, respectively. HELF-EGFP and SMMC-7721-EGFP cells stably expressing EGFP or hTERT were constructed. GFP expression was inhibited in both HELF-EGFP and SMMC-7721-EGFP cells expressing shRNA-EGFP-U6. Further results showed that GFP expression was suppressed only in telomerase positive SMMC-7721 cells and HepG2 cells, but not in telomerase negative HELF cells expressing shRNA-EGFP-hTERT/U6. Further results found that hTERT expression was effectively inhibited from liver cancer cells expressing shRNA-hTERT-U6 or shRNA-hTERT-hTERT/U6 both in vitro and in vivo. Our study illustrates the tumor-targeted efficiency of shRNA vectors harboring chimera hTERT/U6 promoter in telomerase positive cells, which will benefit tumor therapy.