Analysis of the Frequency Shift versus Force Gradient of a Dynamic AFM Quartz Tuning Fork Subject to Lennard-Jones Potential Force.

A self-sensing and self-actuating quartz tuning fork (QTF) can be used to obtain its frequency shift as function of the tip-sample distance. Once the function of the frequency shift versus force gradient is acquired, the combination of these two functions results in the relationship between the force gradient and the tip-sample distance. Integrating the force gradient once and twice elucidates the values of the interaction force and the interatomic potential, respectively. However, getting the frequency shift as a function of the force gradient requires a physical model which can describe the equations of motion properly. Most papers have adopted the single harmonic oscillator model, but encountered the problem of determining the spring constant. Their methods of finding the spring constant are very controversial in the research community and full of discrepancies. By circumventing the determination of the spring constant, we propose a method which models the prongs and proof mass as elastic bodies. Through the use of Hamilton's principle, we can obtain the equations of motion of the QTF, which is subject to Lennard-Jones potential force. Solving these equations of motion analytically, we get the relationship between the frequency shift and force gradient.

The risk factors of progestational anxiety, depression, and sleep disturbance in women with recurrent pregnancy loss: A cross-sectional study in China.

Background: The risk factors of progestational anxiety, depression, and sleep disturbance in women with a history of recurrent pregnancy loss (RPL) remain controversial, additional study is needed to investigate the incidence and risk factors of progestational anxiety, depression, and sleep quality in RPL women. Methods: A cross-sectional study was conducted among 663 non-pregnant RPL women in Northeast China from October 2019 to July 2022. We assessed the state of anxiety, depression, and sleep quality before pregnancy using structured questionnaires, including sociodemographic characteristics, state-trait anxiety scale (STAI), center for epidemiological survey, depression scale (CES-D), Pittsburgh sleep quality index (PSQI), and symptom self-rating scale (SCL-90). Logistic regression was used to evaluate the association between sleep quality and anxiety, depression. Pearson's correlation was used to evaluate the correlation between anxiety and depression. Multivariate logistic regression analysis was used to find the risk factors of depression symptoms. The receiver operating characteristic curve (ROC) was used to evaluate the predictive value of the model. Results: The incidence of state anxiety, trait anxiety, depression, and sleep disturbance in RPL women were 60.3, 51.7, 33.9, and 31.2%, respectively. The level of anxiety and depression in RPL women varied at different stages of treatment. In a longitudinal study (25 pairs), we found the level of state anxiety and trait anxiety were significantly lower after the cause was identified. Sleep disturbance is positively correlated with anxiety and depression. Logistic regression showed that the number of miscarriages ≥4 (Odds ratio (OR) = 2.268, 95%CI 1.300-3.956), Low household family income (OR = 1.613, 95%CI 1.036-2.513/OR = 2.361, 95%CI 1.095-5.092), interval since last miscarriage <6 months (OR = 2.154, 95%CI 1.246-3.726) and sleep disturbance (OR = 5.523, 95%CI 3.542-8.614) were associated with the occurrence of depressive symptoms. At the same time, anxiety can be used as a predictor of depression. Conclusion: Recurrent pregnancy loss women have a certain degree of anxiety, depression, and sleep disturbance. Education level, interval since the last miscarriage <6 months, and sleep disturbance are risk factors for anxiety and depression. A history of pregnancy loss after 14 weeks and no living birth are also closely related to anxiety. Therefore, it is necessary to pay close attention to the psychological state of RPL women and provide appropriate psychosocial support to reduce the occurrence of negative emotions.

The sequence and de novo assembly of hog deer genome.

Hog deer (Axis porcinus) is a small deer species in family Cervidae and has been undergoing a serious and global decline during the past decades. Chengdu Zoo currently holds a captive population of hog deer with sufficient genetic diversity in China. We sequenced and de novo assembled its genome sequence in the present study. A total of six different insert-size libraries were sequenced and generated 395 Gb of clean data in total. With aid of the linked reads of 10X Genomics, genome sequence was assembled to 2.72 Gb in length (contig N50, 66.04 Kb; scaffold N50, 20.55 Mb), in which 94.5% of expected genes were detected. We comprehensively annotated 22,473 protein-coding genes, 37,019 tRNAs, and 1,058 Mb repeated sequences. The newly generated reference genome is expected to significantly contribute to comparative analysis of genome biology and evolution within family Cervidae.

Application study of medical robots in vascular intervention.

BACKGROUND: Based on the background of minimally invasive surgery and applications of medical robots, a vascular interventional robotic system has been developed that can be used in the field of vascular intervention. METHODS: The robotic system comprises a propulsion system, an image navigation system and a virtual surgery training system. Integration of the three systems constitutes a vascular intervention prototype robotic system used to carry out in vitro vascular intervention and animal experiments. RESULTS: On a transparent glass vascular model, a catheter was shown to enter an arbitrary branch of the vascular model with catheter motion meeting the requirements of clinical vascular intervention surgery (VIS); i.e. error band of catheter motion < 0.5 mm. In the animal experiments, 1.33-2.00 mm (4F-6F) diameter catheters were selectively inserted successfully into predefined targets in the animal, such as the renal, cardiovascular and cerebrovascular artery. Compared with conventional manual surgery, the time for robotic surgery is a little longer. There were no operative complications in the animal experiments. CONCLUSIONS: These simulation and animal study results demonstrate that this vascular interventional robotic system allows doctors to perform angiography remotely and prevents them from radiation exposure. The system may be the basis for further clinical applications of vascular intervention.