[en] The wireless sensor network (WSN) technology has been utilized to design a new regional environmental radiation monitoring system based on the wireless sensor networks to meet the special requirements of monitoring the nuclear radiation in certain regions, and realize the wireless transmission of measurement data, information processing and integrated measurement of the nuclear radiation and the corresponding environmental parameters in real time. The system can be applied to the wireless monitoring of nuclear radiation dose in the nuclear radiation environment. The measured data and the distribution of radiation dose can be vividly displayed on the graphical interface in the host computer. The system has functioned with the wireless transmission and control, the data storage, the historical data inquiry, the node remote control. The experimental results show that the system has the advantages of low power consumption, stable performance, network flexibility, range of measurement and so on. (authors)

[en] Objective: To discuss the value of T₂ relaxation time in the research of the biomechanics and function of cartilage of knee joint. Methods: Knees of 20 healthy adults and 19 osteoarthritis patients were examined with sagittal 8-echo sequence. The T₂ value of cartilage was calculated. The T₂ values in the superficial and deeper cartilage of femoral and tibial joint were compared, so did between the osteoarthritis patients and healthy adults. Results: The T₂ values in the superficial and the deeper tibital cartilage were (48.8±6.3) ms, (44.3±5.7) ms, respectively. The T₂ values in the superficial and deeper femoral cartilage were (52.1±5.7) ms, (47.7±5.3) ms, respectively. There was a significant difference between superficial and deeper femoral cartilage (t=3.148 and t=3.384, P<0.01). The mean T₂ value in the tibial cartilage of osteoarthritis patients was (56.0±9.1) ms and was higher than that of healthy adults. There was a significant difference between osteoarthritis patients and healthy adults (t=-3.446, P<0.01). Conclusion: T₂ relaxation time can be used in the research of the biomechanics and function of cartilage and has a application value in clinical diagnosis. (authors)

[en] Objective: To investigate the effect of slice orientation on the popliteomeniscal fasciculi (PMF) MR imaging and its normal MRI appearances. Methods: Volumetric MRI data of 40 knees of healthy volunteers were acquired using an isotropic 3D turbo spin echo (TSE) MR sequence. The posterior tangential line to both femoral condyles was used as the reference line, and the long axis sectional images of the popliteal hiatus region were reformatted at 0 degree, 15 degree, 30 degree, 45 degree, 60 degree, 75 degree and 90 degree to the reference line. The MRI appearances of the PMF were scored respectively and classified. The final scores of the PMF at each slice angle were statistically analyzed by a repeated measure ANOVA. Results: At 0 degree, 15 degree, 30 degree, 45 degree, 60 degree, 75 degree and 90 degree slice angles: scores of the anteroinferior fasciculi were (1.7±0.7), (1.8±0.6), (1.9±0.6), (2.0±0.7), (1.9±0.7), (1.8±0.8) and (1.0±0.5), respectively. Scores of the posterosuperior fasciculi were (1.5±0.7), (1.9±0.7), (2.1±0.6), (2.2±0.6), (2.2±0.6), (2.0±0.8) and (1.7±0.8), respectively. There were statistically significant differences in the average scores at each slice angle for both anteroinferior fasciculi (F=29.744, P=0.000) and posterosuperior fasciculi (F=19.770, P=0.000). The anteroinferior fasciculi and the posterosuperior fasciculi had highest average scores at the angle of 45 degree. The percentage of type A, B and C of anteroinferior fasciculi were 20.0% (8/40), 75.0% (30/40)and 5.0% (2/40), respectively. The percentage of type A, B and C of posterosuperior fasciculi were 37.5% (15/40), 62.5% (25/40) and 0% (0/40), respectively. Conclusion: The anteroinferior fasciculi and the posterosuperior fasciculi can be well depicted at the angle of 45 degree slice orientation. (authors)

[en] Objective: To investigate the relationship between bone mineral density (BMD) of lumbar spine and abdominal adipose tissue in adult males. Methods: A total of 1374 healthy male examinees in;the Affiliated Hospital of Guizhou Medical University from June 2018 to September 2018 were retrospectively analyzed. The age ranged from 30 to 75 (50.9 ± 0.30) years. Height, weight and waist circumference was measured and body mass index (BMI) was calculated. Quantitative CT (QCT) was used to measure the mean BMD value of L1 and L2. The abdominal subcutaneous fat area (SFA) and visceral fat area (VFA) at the level of L2 were measured as well. According to the BMD, the males were divided into three groups: normal group, osteopenic group and osteoporosis group. One-way ANOVA was applied to compare the age, BMI, VFA and SFA among three groups. LSD-t test was used for multiple comparisons, and Pearson correlation was used to analyze the correlation between age, BMI, VFA, SFA and lumbar BMD. Results: Totally 807 healthy males were in normal group, 451 in osteopenic group and 116 in osteoporosis group. There were significant differences in age, BMI and VFA among normal group, osteopenic group and osteoporosis group (F = 237.939, 5.788, 4.919, P < 0.001, 0.003, 0.007). Age and VFA was higher in osteopenic group compared with normal group, and BMI was lower in osteopenic group compared with normal group. Age was higher in osteoporosis group compared with normal group, and the BMI was lower in osteoporosis group compared with normal group. The age was higher in osteoporosis group compared with osteopenic group. The above differences were statistically significant (P < 0.05). Although there was no statistical difference in VFA and SFA between osteopenic group and osteoporosis group, the VFA and SFA was higher in osteopenic group compared with osteoporosis group. BMD of male lumbar spine was negatively correlated with age (r = -0.542, P < 0.001), VFA (r = -0.104, P < 0.001), and positively correlated with BMI (r = 0.109, P < 0.001). After controlling for age and BMI, BMD was still negatively correlated with VFA (r = -0.129, P < 0.05). Conclusions: Males with abdominal obesity is more likely to manifest as low bone mass. The lumbar BMD is possibly negatively correlated with visceral adipose tissue in male. (authors)

[en] Objective: To discuss the value of MR T₂ mapping in the research of the biomechanics and function of cartilage of knee joint. Methods: Knees of 20 healthy adults before and after jogging and 19 osteoarthritis patients were examined with sagittal 8-echo SE sequence. The T₂ value of cartilage was selected and calculated. The T₂ values in the superficial and deep cartilage of femoral and tibial joint before and after jogging were compared, so did between the osteoarthritis patients and healthy adults. The source images were sent to the workstation to get T₂ mappings. The T₂ value of cartilage between before and after jogging was compared with paired-samples t test. The T₂ value between superficial and deep cartilage before jogging was compared with independent-samples t test, so did between the osteoarthritis patients and healthy adults. Results: The T₂ values in the superficial and the deep tibial cartilage were (48.8±6.3) ms, (44.3±5.7) ms before jogging and (43.4±5.0) ms, (40.3±6.1) ms after jogging. The T₂ values were significantly different between before and after jogging (t=6.004 and t=5.037, P<0.05). There was a significant difference between superficial and deep tibial cartilage before jogging (t=3.148, P<0.01). The T₂ values in the superficial and deep femoral cartilage were (52.1±5.7) ms, (47.7±5.3) ms before jogging and (47.2±4.5) ms, (43.6±4.1) ms after jogging. The T₂ values were significantly different between before and after jogging (t=6.169 and t=5.957, P<0.05). There was a significant difference between superficial and deep femoral cartilage before jogging(t=3.384, P<0.01). The T₂ mapping showed those changes. The mean T₂ value in the tibial cartilage of osteoarthritis patients was (56.0±9.1) ms and was higher than that of healthy adults. There was a significent difference between osteoarthritis patients and healthy adults (t=-3.446, P<0.01). Conclusion: T₂ mapping can be used in the research of biomechanics and function of cartilage and has a prelimilary value in the diagnosis of cartilage degeneration. (authors)

[en] CrAlN coating with moderate Cu content was deposited on the surface of 1Cr18Ni9Ti stainless steel by DC reactive magnetron sputtering. The oxidation behavior under 800°C of the coatings was investigated emphatically in this research. The phase construction, microstructure and chemistry contents were analyzed by X-ray diffraction (XRD), field-emission electron scanning microscope (FESEM) and energy disperse spectroscopy (EDS). And the mechanical properties of the coatings were measured by microhardness tester and multi-function scratcher. As a comparison, the properties of CrAlN coating were also analyzed in the article. The results showed that the microstructure of CrAlCuN coating became smother and denser with a phase structure of CrN and Cu. With Cu doped in the CrAlN coating, the more excellent hardness which enhanced to 48.37 GPa was obtained. While the bonding strength of the coating was decreased because of the advanced microhardness usually released more internal stress. Both of the coatings were not complete failure and CrN diffraction peak was also tested. The oxidation rate of weight gain had significantly decreased with Cu doped, which improved the resistance of high temperature oxidation to a certain extent. (paper)

[en] Objective: To determine the CT and MRI appearance of intracerebral ependymoma. Methods: CT and MRI of 16 patients (4 men and 12 women, age range: 29-63 years, median: 50 years) with histologically confirmed intracerebral ependymomas were analyzed retrospectively. Results: The tumors were supratentorial (12) or infratentorial (4), mixed solid and cystic (12) or solid (4). All 16 lesions were large and irregular with well-defined borders and no surrounding edema. Calcifications were shown in 8 cases. The tumors were heterogeneous on both CT and MRI with calcifications in 8 patients, heterogeneous intermediate to marked contrast enhancement. Conclusions: The CT and MRI appearance of intracerebral ependymoma is specific and can provide comprehensive information for treatment planning. (authors)

[en] The fascinating Dirac cone in honeycomb graphene, which underlies many unique electronic properties, has inspired the vast endeavors on pursuing new two-dimensional (2D) Dirac materials. Based on the density functional theory method, a 2D material Zn₃Si₂ of honeycomb transition-metal silicide with intrinsic Dirac cones has been predicted. The Zn₃Si₂ monolayer is dynamically and thermodynamically stable under ambient conditions. Importantly, the Zn₃Si₂ monolayer is a room-temperature 2D Dirac material with a spin–orbit coupling energy gap of 1.2 meV, which has an intrinsic Dirac cone arising from the special hexagonal lattice structure. Hole doping leads to the spin polarization of the electron, which results in a Dirac half-metal feature with single-spin Dirac fermion. This novel stable 2D transition-metal-silicon-framework material holds promises for electronic device applications in spintronics. (paper)

[en] In order to enhance the wear resistance of material surface, the hardfacing alloy is usually deposited on its surface by using plasma surfacing technology (PST). The technology has the advantages of the low dilution rate, small deformation, smooth welding path, food metallurgical combination, and no major defects. In this paper, a Fe-based alloy coating had been prepared by PST, and the structure and properties of surfacing layer had been studied. The results showed that the hardness of surfacing layer was significantly greater than that of the substrate. And the coating layer had a snowflake-like structure. Its Lorraine hardness was up to about 60HRC, and the friction coefficient was about half of the 65Mn after quenching. With the increase of the material hardness, the coating layer has excellent abrasion resistance. (paper)

[en] Highlights: • A novel synthesis of Nano-CeO₂@Co₃O₄ from complexation and impregnation was tried. • Activities were remarkably promoted by applying of nano-materials and microwave. • Kinetic studies on catalytic oxidation under microwave radiation were presented. • Microwave absorption properties were first provided for evaluation of activities. • A possible mechanism on catalytic oxidation under microwave radiation was showed. -- Abstract: Cleaner production in spraying processing was presented by advanced low temperature oxidation technology using combined methods of microwave radiation and nano-composites. Activities of samples for oxidation of toluene were estimated and the result exhibited that application of microwave radiation and nano-materials greatly promoted activities of catalysts. Moreover, the doping of Ce further enhanced catalytic activities. Samples of 5% Ce-Co showed optimal activity with conversion rate of 70% and CO₂ selection of 96% at 120 ℃ and 210 ℃, respectively. The lowest E_a (33.45 kJ/mol) was obtained calculating from kinetics process under microwave radiation using 5% Ce-Co indicating that the degradation of toluene might proceed more readily. Microwave absorption properties were first used tentatively to study the effect of “hot spots” induced by microwave radiation on catalytic oxidation of VOCs. Further, physicochemical properties of samples were also showed by XRD, SEM and XPS profiles to study oxidation activities of toluene. The maximum difference of toluene oxidation between no water and in water using 5% Ce-Co at 210 ℃ was only 3.06% manifesting that effects of moisture on activities were weak under microwave radiation. A possible degradation track using microwave heating was presented by the analysis of reaction byproducts using the GC–MS.