Design of multi-frequency point, high-isolation switches for micro-channel plate data acquisition.

In order to replace the phosphor screen of a proximity-gated x-ray framing camera with a readout circuit using a time-interleaved structure, this paper carries out the design of a high-isolation RF switch. In this paper, a Metal-Oxide-Semiconductor Field Effect Tube (MOSFET) switching circuit is designed to achieve high isolation and low insertion loss at 0.5-3 GHz. This solves the problem that the switching circuit cannot be turned off properly due to the parasitic capacitance of MOSFETs in the process of RF signal transmission, resulting in signal feedthrough. It also ensures that the input signal can be transmitted to the output intact when the switching circuit is turned on. High isolation is achieved by using parallel resonance to increase the voltage division and series resonance to leak the current. The switch achieves 76 dB isolation and 0.07 dB insertion loss at 1 GHz frequency. Isolation is increased by adding parallel branches near the 2 and 3 GHz frequency points, achieving greater than 33 dB isolation from 0.5 to 3 GHz.

A large-format streak tube for compressed ultrafast photography.

Streak cameras are powerful imaging instruments for studying ultrafast dynamics with the temporal resolution ranging from picosecond to attosecond. However, the confined detection area limits the information capacity of streak cameras, preventing them from fulfilling their potential in lidar, compressed ultrafast photography, etc. Here, we designed and manufactured a large-format streak tube with a large-size round-aperture gate, a spherical cathode, and a spherical screen, leading to an expanded detection area and a high spatial resolution. The simulation results show that the physical temporal resolution of the streak tube is better than 45 ps and the spatial resolutions are higher than 14 lp/mm in the whole area of 24 × 28 mm2 on the cathode. The experiments demonstrate the streak tube's application potential in weak light imaging benefiting from the imaging magnification of 0.79, a photocathode radiance sensitivity of 37 mA/W, a radiant emitting gain of 11.6 at the wavelength of 500 nm, and a dynamic range higher than 512:1. Most importantly, in the photocathode area of Φ35 mm, the static spatial resolutions at the center and the edge along the slit (R = 16 mm) reach 32 and 28 lp/mm, respectively, and are higher than 10 lp/mm in the whole area of 24 × 28 mm2 on the cathode, allowing for a considerable capacity for spatial information.

[Efficacy and safety of intravenous combined with topical administration of tranexamic acid in reducing blood loss after intramedullary fixation of intertrochanteric femoral fractures].

OBJECTIVE: To investigate the efficacy and safety of intravenous combined with topical administration of tranexamic acid (TXA) in reducing blood loss after intramedullary fixation of intertrochanteric femoral fractures by a prospective controlled trial. METHODS: Patients with intertrochanteric femoral fractures, who were admitted for intramedullary fixation between June 2015 and July 2019, were selected as the study subjects, 120 of whom met the selection criteria. The patients were randomly assigned to 3 groups: intravenous administration group (group A, 41 cases), topical administration group (group B, 40 cases), and combined administrations group (group C, 39 cases). In group A, 4 patients occurred deep vein thrombosis of lower extremity before operation, 1 patient died of myocardial infarction on the 5th day after operation, and 1 patient developed severe pulmonary infection after operation. In group B, 2 patients occurred deep vein thrombosis of lower extremity before operation and 1 patient had iatrogenic fracture during operation. In group C, 3 patients occurred deep vein thrombosis of lower extremity before operation and 1 patient developed pulmonary infection before operation and gave up surgical treatment. All the above patients were excluded from the study, and the remaining 107 cases were included in the analysis, including 35, 37, and 35 cases in groups A, B, and C, respectively. There was no significant difference in gender, age, height, body mass, injury cause, fracture side and type, the interval between injury and operation, and preoperative hemoglobin (Hb), hematocrit between groups ( P>0.05). Intraoperative TXA (15 mg/kg) was injected intravenously in group A at 30 minutes before operation, and 1 g of TXA was injected into the medullary cavity in group B after the proximal femur was grooted and before the intramedullary nail implantation, respectively. TXA was given in group C before and during operation according to the administration methods and dosage of groups A and B. Total blood loss, maximum Hb decrease, blood transfusion rate, operation time, fracture healing time, and the incidence of complications were recorded and compared between groups. The hip joint function were evaluated by Harris score. RESULTS: There was no significant difference in operation time between groups ( P>0.05). The total blood loss, the maximum Hb decrease, and the blood transfusion rate in group B were the highest, followed by group A and group C, and the differences between groups were significant ( P<0.05). No incision infection or pulmonary embolism occurred in the 3 groups after operation. The incidence of anemia in group C was significantly lower than that in groups A and B, the difference was significant ( P<0.05). There was no significant difference in the incidence of subcutaneous hematoma, aseptic exudation, and deep vein thrombosis of lower extremity between groups ( P>0.05). All patients in the 3 groups were followed up 8-35 months, with an average of 16.2 months. The fracture healing time of groups A, B, and C was (6.12±1.78), (5.89±1.63), and (5.94±1.69) months, respectively, and there was no significant difference between groups ( P>0.05). At last follow-up, the Harris scores of the hip joints in groups A, B, and C were 83.18±7.76, 84.23±8.01, and 85.43±8.34, and the difference was not significant ( P>0.05). CONCLUSION: Preoperative intravenous injection combined with intraoperative topical application of TXA can effectively reduce blood loss and blood transfusion after intramedullary fixation of femoral intertrochanteric fracture, without increasing the risk of deep vein thrombosis, and the efficacy is better than that of intravenous injection or topical administration.

[Short-term effectiveness comparison of unipedicular versus bipedicular percutaneous kyphoplasty for osteoporotic vertebral compression fractures with posterior wall broken].

OBJECTIVE: To compare the short-term effectiveness and safety of unipedicular versus bipedicular percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fracture (OVCF) with posterior wall broken. METHODS: The clinical data of 68 patients with OVCF with posterior wall broken and without posterior ligament complex injury and spinal cord nerve injury between June 2013 and December 2018 were retrospectively analyzed. According to the different operative approaches, the patients were divided into two groups: group A (36 cases received PKP via bilateral pedicle puncture) and group B (32 cases received PKP via unilateral pedicle paracentesis). There was no significant difference between the two groups in gender, age, fracture vertebra distribution, time from injury to operation, preoperative pain visual analogue scale (VAS) score, Oswestry disability index (ODI), and height of injured vertebra ( P>0.05). The operation time, intraoperative fluoroscopy times, and bone cement volume were recorded and compared between the two groups. The VAS score and ODI score were used to evaluate the effectiveness before operation, at 1 day and 6 months after operation; the height of injured vertebra was measured on the lateral X-ray film, and the recovery height of injured vertebra at 1 day after operation and the loss height of injured vertebra at 6 months after operation were calculated; the intraoperative and postoperative complications of the two groups were recorded. RESULTS: The operation time, intraoperative fluoroscopy times, and bone cement volume of group B were significantly less than those of group A ( P<0.05). All patients were followed up 10-35 months, with an average of 18 months. During the operation, there were 2 cases (5.56%) of cement leakage in group A and 9 cases (28.13%) in group B, showing significant difference ( χ 2=4.808, P=0.028). There was no adverse reactions of bone cement, iatrogenic spinal cord injury, infection of puncture port, or other complications in the two groups. During the follow-up period, there were 3 cases (8.3%) of adjacent vertebral fractures in group A and 2 cases (6.3%) in group B, showing no significant difference between the two groups ( χ 2=0.027, P=0.869). The height of injured vertebra of the two groups at 1 day and 6 months after operation were significantly improved when compared with preoperative ones ( P<0.05). There was no significant difference in the height of injured vertebrae and the recovery height of injured vertebra at 1 day after operation between the two groups ( P>0.05). However, at 6 months after operation, the height of injured vertebra in group B was significantly lower than that in group A ( P<0.05), and the loss height of injured vertebra in group B was significantly higher than that in group A ( P<0.05). The VAS score and ODI score at 1 day and 6 months after operation were significantly improved when compared with preoperative ones in both groups ( P<0.05), but there was no significant difference between the two groups ( P>0.05). CONCLUSION: Both bipedicular and unipedicular PKP can obtain satisfactory effectiveness for the treatment of OVCF with posterior wall broken, but the former may have advantages of lower cement leakage rate and less height loss.

Sedative depth on neurological outcomes in a juvenile rat model of cardiopulmonary resuscitation.

The guidelines for cardiopulmonary resuscitation (CPR) in pediatric advanced life support suggest that midazolam is the preferred agent for sedation in patients with mild hypothermia, whereas children with cardiac arrest (CA) are at a crucial stage regarding their immature nervous system. Studies have shown that midazolam may have a detrimental effect on the developmental of the pediatric nervous system. Our previous study found that midazolam induced neuronal damage after CPR in young rats. It is speculated that: midazolam causes the potential injury of neurons by inhibiting mitochondrial autophagy expression and is an important factor for the poor prognosis in children after successful CPR. This project intends to adopt the modified asphyxiant CPR model in juvenile rats. Survival rate, neurological function and histopathological changes were evaluated to determine the protective effects of appropriate sedation depth on cerebral ischemia-reperfusion injury in juvenile rats after CPR. Combined with cell biology and molecular biology related technologies, the mechanism by which the mitochondrial pinkl-parkin signaling pathway induces autophagy to inhibit neuronal apoptosis may be key factor in the protective effects of sedation depth on the brain. The aim of this study is to provide experimental evidence and elucidate the mechanisms of improvement of cerebral ischemia-reperfusion injury by sedation depth in children after successful CPR and to lay a theoretical and experimental basis for clinical treatment.

[Clinical study for preoperative traction on impact of osteonecrosis of femoral head in patients with femoral neck fractures].

OBJECTIVE: To explore the impact of preoperative traction on the osteonecrosis of the femoral head (ONFH) in patients with femoral neck fractures. METHODS: Between February 2013 and May 2016, 120 patients with femoral neck fractures, who were treated with screw fixation, were collected. Sixty patients with fractures of Garden type Ⅰ and Ⅱ were non-displaced fracture group; 60 cases with fractures of Garden type Ⅲ and Ⅳ were displaced fracture group. The patients in 2 groups were randomly divided into traction and non-traction subgroups ( n=30). There was no significant difference in gender, age, injury mechanism, damage side, the time from injury to operation, and fracture classification between 2 subgroups ( P>0.05). Intracapsular pressure was recorded before operation. The quality of fracture reduction and the satisfaction ratio of screw implant were evaluated during operation. Visual analogue scale (VAS), Harris score, joint mobility, and the incidence of ONFH would be evaluated at 6 months, 1 year, and 2 years after operation. RESULTS: All incisions of 2 groups healed by first intention after operation. There was no infection or deep vein thrombosis of lower extremity. All patients were followed up 2 years. In displaced and non-displaced fracture groups, the intracapsular pressure of traction subgroups were higher than that of non-traction group ( P<0.05); the differences of the quality of fracture reduction and the satisfaction ratio of screw implant were not significant ( P>0.05) between 2 subgroups. At 6 months, 1 year, and 2 years after operation, VAS scores were higher in traction subgroup than in non-traction subgroup ( P<0.05); and the joint mobility and Harris scores were lower in traction subgroup than in non-traction subgroup ( P<0.05). X-ray films showed all fractures healed. Except for the non-displaced group at 6 months, the incidences of ONFH were higher in traction subgroup than in non-traction subgroup at other time points ( P< 0.05). CONCLUSION: Preoperative traction may increase the risk of ONFH, which can increase the intracapsular pressure and affect the blood supply of femoral head.

High-Sensitivity and Long-Life Microchannel Plate Processed by Atomic Layer Deposition.

As a key component of electron multiplier device, a microchannel plate (MCP) can be applied in many scientific fields. Pure aluminum oxide (Al2O3) as secondary electron emission (SEE) layer were deposited in the pores of MCP via atomic layer deposition (ALD) to overcome problems such as high dark current and low lifetime which often occur on traditional MCP. In this paper, we systematically investigate the morphology, element distribution, and structure of samples by scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS), respectively. Output current of different thickness of Al2O3 was studied and an optimal thickness was found. Experimental tests show that the average gain of ALD-MCP was nearly five times better than that of traditional MCP, and the ALD-MCP showed better sensitivity and longer lifetime.

Analgesic therapy improves arterial endothelial function following non-cardiovascular surgery: A randomized, placebo-controlled trial.

Pain subsequent to non-cardiac surgery may affect the endothelial function, which in turn contributes to myocardial injury (MI). The present study examined whether effective pain control is able to improve the postoperative endothelial function. Patients (n=160) undergoing laparoscopic cholecystectomy were randomly assigned into two groups, treated with tramadol analgesic or saline (placebo) following surgery. On preoperative day 1 (baseline) and postoperatively at 2 h, 1 day and 5 days, pain was assessed on a visual analogue scale (VAS), and B-mode ultrasound was used to measure brachial endothelium-dependent flow-mediated dilation (FMD) and nitroglycerin-induced dilation. At 2 h postoperatively, the FMD in the two groups was significantly lower compared with that at the other three time points (P≤0.005), while VAS was significantly higher (P<0.05). Patients in the tramadol group presented significantly reduced VAS values in comparison with those in the placebo group at 2 h and 1 day postoperatively (P=0.013 and 0.031, respectively), as well as significantly higher FMD at 2 h (6.7±1.5 vs. 6.0±1.7%; P=0.001) and 1 day postoperatively (7.3±1.3 vs. 6.9±1.4%; P=0.03). A VAS score of <5 was independently associated with postoperative FMD of ≥7 (odds ratio, 2.5; 95% confidence interval, 1.0-6.0; P=0.047). Backward multivariate linear regression also demonstrated that FMD was independently correlated with age and VAS score (B=-1.403, P=0.011; B=-0.579, P=0.003). The response to nitroglycerin-induced dilation remained stable in all patients at baseline and at all postoperative time points. In conclusion, analgesic treatment may improve the arterial endothelial function following non-cardiac surgery, which may help prevent postoperative MI.

[Effect of functional exercise at different time and different immobilization positions on functional recovery of elbow joint with type C distal humeral fractures].

Objective: To investigate the effect of functional exercises at different time and different immobilization positions on the functional recovery of elbow joint with type C distal humeral fractures. Methods: A total of 120 patients with type C distal humeral fractures admitted to the hospital between June 2013 and July 2015 were included in the study. They were randomly allocated to 3 groups, 40 patients in each group. Group A: functional exercises began immediately after the operation; Group B: the affected elbow was fixed at 90° flexion for 1 week and then began functional exercises after 1 week of immobilization; Group C: the affected elbow was fixed at 30° extension for 1 week and then began functional exercises after 1 week of immobilization. There was no significant difference in gender, age, fracture pattern, fracture side, injury time, and surgical approach between groups ( P>0.05). Results: In groups A and B, 1 case had incision redness and swelling respectively, and the other incisions healed by first intention. Five patients occurred myositis ossificans in group A, 4 cases in group B, and 5 cases in group C. The incidence of complications in groups A, B, and C was 15.0% (6/40), 12.5% (5/40), and 12.5% (5/40), respectively. There was no significant difference between groups ( χ2=0.144, P=0.930). All patients were followed up 6-25 months, with an average of 9.8 months. At 2 weeks after operation, the Mayo elbow joint function score of group A was significantly higher than those of groups B and C ( P<0.05), and the visual analogue scale (VAS) of group A was significantly lower than those of groups B and C ( P<0.05). There was no significant difference between groups B and C ( P>0.05). At 6 months after operation, there was no significant difference in Mayo elbow joint function score and VAS score between groups ( P>0.05). At 2 weeks and 6 months after operation, the flexion and extension activities of elbow joint in groups A and C were better than that in group B ( P<0.05), and there was no significant difference between groups A and C ( P>0.05). There was no significant difference in forearm rotation between groups ( P>0.05). All fractures of 3 groups achieved clinical healing, and there was no significant difference in healing time between groups ( P>0.05). Conclusion: Early functional exercises can relieve pain and obtain better elbow flexion and extesion activities after operation. The elbow joint fixed at 30° extension is better than at 90° flexion in elbow flexion and extension activitis.

Three-dimensional reconstruction of laser-imploded targets from simulated pinhole images.

This paper proposes an integral method to achieve a more accurate weighting matrix that makes very positive contributions to the image reconstruction in inertial confinement fusion research. Standard algebraic reconstruction techniques with a positivity constraint included are utilized. The final normalized mean-square error between the simulated and reconstructed projection images is 0.000365%, which is a nearly perfect result, indicating that the weighting matrix is very important. Compared with the error between the simulated and reconstructed phantoms, which is 2.35%, it seems that the improvement of the accuracy of the projection image does not mean the improvement of the phantom. The proposed method can reconstruct a simulated laser-imploded target consisting of 100×100×100 voxels.

[Research on the method of transient spectrum detection based on array CCD].

Based on the characteristic of high speed line scanning for CCD in transient spectrum detection, a method of transient spectrum detection with array CCD is presented. The high speed line scanning with array CCD was realized by changing the mode of charge transfer. In order to explore the feasibility of this method, a fast detection system of single point based on linear CCD was designed and fabricated. Seven different LED pulses were measured when the system worked at fast detection mode of single point and normal mode respectively. The results demonstrate that the method of fast detection of single point based on linear CCD is feasible, and the rate of single point detection reaches up to 20 MHz. Thus, in theory, it was proved that transient spectrum detection with array CCD by changing the mode of charge transfer is also feasible.

[Real-time measurement of detonation transient temperature].

Based on the spectral characteristic of the detonation temperature, the present paper presents a measurement system of transient multi-wavelength pyrometry with the theory of multi-wavelength thermometry. The FPGA was applied as the hardware developing platform and the high-speed linear CCD was utilized. Each module was controlled by FPGA to achieve the process of real-time data acquisition, storage and transmission. Using the multiple regression analysis method, the dynamic spectral waveforms were calculated. The two laser spectral lines, 630 and 532 nm, were used to calibrate the corresponding pixel sequence numbers and the No. 175 and No. 270 were confirmed. In this paper, the halide tungsten light was measured. The results show that the system can sample continuous spectrum signal at several different times; the CCD can stably work with 40 MHz clock and the frame scanning frequency can achieve 73 kHz.

[An animal model of Perthes disease and an experimental research of VEGF expression].

OBJECTIVE: To make a rabbit model of Perthes disease and to explore the change and its significance of VEGF expression in the femoral head. METHODS: Twenty-four 3-month-old New Zealand rabbits (weighing 1.6-1.8 kg) were randomly divided into experimental group (n=16) and control group (n=8). A rabbit model of Perthes disease was made by excision of left ligamentum teres and retinacular blood supplies of femoral head. The gross appearance, X-ray film and histological observations were made and the immunohistochemistry and VEGF mRNA in situ hybridization were carried out 1, 2, 4, 8 weeks after operation. RESULTS: The rabbit model of Perthes disease was made successfully; only 1 was infected 5 days after operation and was made quit. The gross appearance: The femoral heads had no necrosis changes in control group at every time. The femoral heads became coarse, tarnish and smaller, and even collapsed in experimental group. The HE staining observation: The femoral heads had no necrosis changes in control group at every time after operations. New vessels and granulation tissues grew into the necrosis part in the experimental group 4 weeks and 8 weeks after operations. New bone could be seen in repaired bone. Immunohistochemistry staining: In the epiphyseal cartilage of the femoral heads in control group, an intensive VEGF immunoreactivity (VEGF-IR) was found in the hypertrophic zone with a low level of VEGF-IR in the proliferative zone. At 1 week after operation, the percentage of VEGF+ cells in the proliferative zone of the femoral heads in experimental group was increased compared with that of the femoral heads in control group. The percentage of VEGF+ cells in the hypertrophic zone of the femoral heads in experimental group was significantly decreased compared with that of the femoral heads in control group. At 8 weeks after operation, VEGF-IR was observed throughout the epiphyseal cartilage surrounding the bony epiphysis in the femoral heads in experimental group. The percentage of VEGF-positive cells in the proliferative zone of the femoral heads in experimental group was significantly increased compared with that of the normal heads. The hypertrophic zone of the femoral heads in experimental group had a similar percentage of the VEGF+ cells to the femoral heads in control group when endochondral ossification was restored at 8 weeks. There were statistically significant differences in the ratios of VEGF+ cells in the proliferative zone of femoral head 1, 2, 4, 8 weeks after operations (P < 0.01); in the ratios of VEGF+ cells in the hypotrophic zone of femoral head 1, 2, 4 weeks after operations (P < 0.01) between experimental group and control group. In situ hybridization results: The results were similar to that of histology. VEGF mRNA expression in the hypertrophic zone of epiphyseal cartilage after necrosis were lower. VEGF mRNA expression in the proliferative zone of epiphyseal cartilage after necrosis increased. VEGF mRNA expression in the hypertrophic zone of epiphyseal cartilage in experimental group could be seen again after endochondral ossification was repaired. CONCLUSION: It is possible that VEGF may act as a key regulator that couples angiogenesis, cartilage remodeling, and ossification after ischemic damage to restore endochondral ossification in the epiphyseal cartilage.