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[en] Objective: To discuss the breast damage caused by the x-ray scanning. Methods: To calculate the chest and breast scanning layers of every case with GE 16 layer-CT machine on 38 female patients, choosing voltage 120 KV, electric current 150 mA, 200 mA, 250 mA and pitch 0.935 or 1.375. then calculate the chest and breast scanning layers of every case, register the bar, where the scan program can be set, record the DLP and work out the DLP of the breast according to data noted above. Meanwhile, analyze the influence of mA, layer, pitch on DLP. Results: In the 38 cases, plane scanning layers of chest range from 19 to 33, and breast from 7 to 19, with the latter accounting for 27.59%-66.66% of the former. So was the DLP. When scanning the same ranges, chose different mAs and pitch, which exerts a great influence on the DLP. Conclusion: Choosing 150 mA, 1.375 pitch, 7.5 mm layer on female of moderate bodily from can guarantee the quality of the picture sufficiently and a relative lower DLP. At the same time, make a good use of its software to rebuild in a variety of ways. Also, a better quality picture can be received. Choosing the parameters such as pitch, numbers of scan layers, slice and mA scientifically can reduce the quantity of X-ray the breast received. (authors)
[en] Objective: To investigate the feasibility of a 4D-CT reconstruction of periodical motion target based on the similarity measure of spatial adjacent images. Methods: A motor driven sinusoidal motion platform made in house was used to create one-dimensional periodical motion that was along the longitudinal axis of the CT couch. CT data of the phantom were acquired using a multi-slice General Electric (GE) LightSpeed 16-slice CT scanner in an axial mode and Cine mode. A software program was developed by using VC + + and VTK software tools to sort the CT data and reconstruct the 4D -CT. Then all of the CT data with same phase were sorted by the program into a same series based on the similarity measure of spatial adjacent images, and 3D reconstruction of different phase CT data were completed by using the software. Results: Compared with the unsorted CT data, the motion artifacts in the 3D reconstruction of sorted CT data were reduced a lot, and all of the sorted CT series result in a 4D-CT that reflected the characteristic of the periodical motion phantom. Conclusions: Time-resolved 4D-CT reconstruction of periodical motion target can be implemented with any general multi-slice CT scanners based on the similarity measure of spatial adjacent images, the process of the 4D-CT data acquisition and reconstruction was not restricted to the hardware or software of the CT scanner and has the feasibility and extensive applicability. (authors)
[en] Objective: Viable myocardium is important to patients with coronary artery disease. The objective of this study was to evaluate the value of dual-isotope simultaneous acquisition SPECT (DISA-SPECT) with 99Tcm-methoxyisobutylisonitrile (MIBI) and 18F-fluorodeoxyglucose (FDG) in detecting viable myocardium (VM). Methods: Twenty-one patients with regional wall motion abnormalities (RWMA) based on routine echocardiography underwent DISA-SPECT, coronary angiography and percutaneous coronary intervention (PCI). Imaging and analysis of the left ventricular myocardial perfusion status were performed according to the 16-segment models proposed by American Society of Echocardiography. The wall motion of every LV segment was observed by echocardiography after 1, 3, 6 months. The images of DISA-SPECT were analyzed semi-quantitatively. The 'gold standard' for true viability was improvement of wall motion of the ventricular segment after PCI. Results: There were 105 viable myocardial segments and 51 non-viable myocardial segments according to the 'gold standard' criterion. The sensitivity, specificity, positive predict value, negative predict value and accuracy of DISA-SPECT in detecting viable myocardium were 93.3% (98/105), 82.4% (42/51), 91.6% (98/107), 85.7% (42/49), 89.7% (140/156), respectively. Conclusion: DISA-SPECT is a valuable technique to detect viable myocardium in patients with coronary artery disease. (authors)
[en] An adjustable quantized approach is adopted to treat the sliding mode control of Markov jump systems with general transition probabilities. To solve this problem, an integral sliding mode surface is constructed by an observer with the quantized output measurement and a new bound is developed to bridge the relationship between system output and its quantization. Nonlinearities incurred by controller synthesis and general transition probabilities are handled by separation strategies. With the help of these measurements, linear matrix inequalities-based conditions are established to ensure the stochastic stability of the sliding motion and meet the required performance level. An example of single-link robot arm system is simulated at last to demonstrate the validity.
[en] Graphical abstract: Low-molecular-weight PDMS coating on the surfaces of non-silicon substrates such as thermoplastics ensures permanent sealing with a silicone elastomer, PDMS, simply by surface oxidization followed by ambient condition bonding, mediated by a robust siloxane bond formation at the interface. - Highlights: • Non-silicon thermoplastic was bonded with poly(dimethylsiloxane) silicone elastomer. • Low-molecular-weight PDMS interfacial layer was chemically coated on thermoplastic. • Bonding was realized by corona treatment and physical contact under ambient condition. • Bonding is universally applicable regardless of thermoplastic type and property. • Homogeneous PDMS-like microchannel was obtained inside the thermoplastic-PDMS microdevice. - Abstract: In this paper, we introduce a simple and robust strategy for bonding poly(dimethylsiloxane) (PDMS) with various thermoplastic substrates to fabricate a thermoplastic-based closed microfluidic device and examine the feasibility of using the proposed method for realizing plastic–plastic bonding. The proposed bonding strategy was realized by first coating amine functionality on an oxidized thermoplastic surface. Next, the amine-functionalized surface was reacted with a monolayer of low-molecular-weight PDMS, terminated with epoxy functionality, by forming a robust amine-epoxy bond. Both the PDMS-coated thermoplastic and PDMS were then oxidized and permanently assembled at 25 °C under a pressure of 0.1 MPa for 15 min, resulting in PDMS-like surfaces on all four inner walls of the microchannel. Surface characterizations were conducted, including water contact angle measurement, X-ray photoelectron spectroscopy (XPS), and fluorescence measurement, to confirm the successful coating of the thin PDMS layer on the plastic surface, and the bond strength was analyzed by conducting a peel test, burst test, and leakage test. Using the proposed method, we could successfully bond various thermoplastics such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polystyrene (PS), and poly(ethylene terephthalate) (PET) with PDMS without the collapse or deformation of the microchannel, and the proposed method was successfully extended to the bonding of two thermoplastics, PMMA, and PC
[en] Highlights: • Three parameters are used to evaluate the startup performance. • The startup is faster and overshoot is larger when the distribution is more uneven. • Heating on one evaporator with same Q with the other makes transition time longer. • Heating on one evaporator with same Q with the other makes the overshoot smaller. • Transition time is about twice as much as peak time when peak time exists. - Abstract: Loop thermosyphon with multiple evaporators is a promising device in multi-source heat transfer. The startup performance is very important for its thermal control ability. In this paper, the effect of heating power distribution on the startup of a loop thermosyphon with dual evaporators is investigated experimentally. The startup time and stationarity under different power distributions are analyzed utilizing three parameters: peak time, transition time and temperature (pressure) overshoot. The results show that the startup process is faster and the overshoot of pressure and temperature is larger when the distribution is more uneven; Heating on one evaporator with the same heating power with the other evaporator makes the startup process longer while it makes the overshoot smaller or even disappear; The transition time is approximately twice as much as the peak time when the peak time exists.
[en] Free cooling based on loop thermosyphon is ideal energy-saving method for data centers. Most working fluids presently used in this field will cause greenhouse effect or destroy the ozone layer. It is necessary to investigate the applicability of environment friendly fluids. A distributed-parameter model of a CO2 loop thermosyphon in an integrated air conditioning system for free cooling is built and validated. The performance is compared with traditional working fluids and the effects of some key geometric parameters are evaluated. The results show that the optimal filling ratios for CO2, R22 and R134a are 120%, 100% and 90%, respectively. The circulation flow rate of CO2 is much smaller than those of R22 and R134a. For CO2 loop thermosyphon, the heat transfer rate decreases with the increase of pipe length, while increases with the increase of riser diameter and height difference. The heat transfer rate increases with the increase of tube number and length of the evaporator, while the increasing rate decreases gradually. The optimal tube number and length are 80 and 0.6 m, respectively. The relationships between the above phenomenon and the internal flow state are also analyzed.