Design of a High-Efficiency and -Gain Antenna Using Novel Low-Loss, Temperature-Stable Li2Ti1-x(Cu1/3Nb2/3)xO3 Microwave Dielectric Ceramics.

Microwave dielectric ceramics are vital for filters, dielectric resonators, and dielectric antennas in the 5G era. It was found that the (Cu1/3Nb2/3)4+ substitution can effectively adjust the TCF (temperature coefficient of resonant frequency) of Li2TiO3 and simultaneously increase its Q × f (Q and f denote the quality factor and the resonant frequency, respectively) value. Notably, excellent microwave dielectric properties (εr (permittivity) ≈ 18.3, Q × f ≈ 77,840 GHz, and TCF ≈ +9.8 ppm/°C) were achieved in the Li2Ti0.8(Cu1/3Nb2/3)0.2O3 (LTCN0.2) ceramic sintered at 1140 °C. Additionally, the sintering temperature of LTCN0.2 was reduced to 860 °C by the addition of 3 wt % H3BO3, exhibiting superior microwave dielectric properties (εr ≈ 21.0, Q × f ≈ 51,940 GHz, and TCF ≈ 1.4 ppm/°C) and being chemically compatible with silver. Moreover, LTCN0.2 + 3 wt % H3BO3 ceramics were designed as a patch antenna and a dielectric resonator antenna, both of which showed high simulated radiation efficiencies (88.4 and 93%) and gains (4.1 and 4.03 dBi) at the center frequencies (2.49 and 10.19 GHz). The LTCN0.2 + 3 wt % H3BO3 materials have promising future application for either 5G mobile communication devices and/or in low-temperature co-fired ceramic technology owing to their high Q, low sintering temperature, small density, and good temperature stability.

PdO/SnO2 heterostructure for low-temperature detection of CO with fast response and recovery.

In this paper, we developed a simple two-step route to prepare a PdO/SnO2 heterostructure with the diameter of the SnO2 and PdO nanoparticles at about 15 nm and 3 nm, respectively. In the evaluation temperature window between 80 °C and 340 °C, PdO/SnO2 shows the best response to 100 ppm of CO at 100 °C with fast response time (14 s) and recovery time (8 s). Furthermore, the PdO/SnO2 nanoparticles exhibit a low detection limit and good selectivity to CO against interfering gases as well as rarely-seen low-temperature stability and reversibility. Such enhanced gas sensing performance could be attributed to both the ultrafine structure of PdO and the synergy between PdO and SnO2. The results clearly indicate the application of PdO/SnO2 as a pratical low-temperature sensing material for CO.

Pd-loaded SnO2 hierarchical nanospheres for a high dynamic range H2S micro sensor.

Herein, a high dynamic range H2S micro gas sensor was achieved using hierarchical Pd-loaded SnO2 nanostructures as a sensing material. SnO2 nanospheres were synthesized using a hydrothermal method without any surfactants or templates, followed by Pd nanoparticle decoration via a facile method. A hierarchical nanostructure of Pd-loaded SnO2 was formed, and its sensing abilities were compared with those of pure SnO2 nanosphere-based sensors. The Pd-loaded SnO2 hierarchical nanostructures showed an ultra-sensitive H2S detection ability down to 10 ppb, a high dynamic range (4 orders of magnitude) up to 200 ppm, and a low working temperature (150 °C). Thus, this micro gas sensor based on Pd-loaded SnO2 hierarchical nanostructures has promising applications in universal H2S detection. The fabrication method presented herein is simple, renewable and operable and thus may be extended to synthesize other types of metal oxide-based semiconductor micro sensors for application in various fields.

Ultrafine nanoparticles of W-doped SnO2 for durable H2S sensors with fast response and recovery.

Ultrafine nanoparticles of W-doped SnO2 with an average diameter of 6 nm were fabricated via a facile hydrothermal method. The material shows a reduced particle size and enhanced response to H2S gas as compared to the pristine SnO2 nanoparticles. The detection limit can be down to 100 ppb while the response time and recovery time of the 5%-doped one are reduced to 17 s and 7 s respectively. In addition, the material shows impressive long-term stability of the response through 40 cycles of injection with 10 ppm H2S, which is attractive for designing a durable hydrogen sulfide sensor. The doping of W results in the reduction of size and modification of the electronic band structure of SnO2, which reduces the response time and recovery time and further improves the sensing durability of the materials.

[Clinical application of hook plate for the treatment of distal clavicular trauma and analysis on its complications].

OBJECTIVE: To discuss the clinical results of hook plate internal fixation for the treatment of distal traumatic injuries of clavicle,and to analysis the mechanism of the complications. METHODS: From 2001.9 to 2008.2, 36 patients with fresh distal clavicle fractures of Neer type II and 14 patients with dislocation of Acromioclavicular joint of Tossy type III were treated with hook plate internal fixations. Among the patients, 36 patients were male and 14 patients were female, ranging in age from 19 to 77 years, with an average of 43 years. After the operation, the range of motion of shoulder joint was measured and the complications were studied. The Karlsson and Constant-Murley criteria were used to evaluate the therapeutic effects. RESULTS: All the patients were followed up with a mean duration of 12 months (7 to 18 months). All the patients could move shoulder joint actively 1 week after operation, and recover to the normal ROM at the 6th week after operation. According to Karlsson criteria, 44 patients got an excellent result, 6 good. According to Constant-Murley criteria, the average score of wound shoulder was (73.8 +/- 8.3) before operation, and (59.6 +/- 6.7) after operation, and the postoperative score was higher than preoperative score. No incision infections were found and 5 patients with complications were cured. No re-dislocation of acromioclavicular joint occurred. CONCLUSION: It is advocated that hook plate for the treatment of distal clavicular fractures of Neer type II and acromioclavicular dislocation of Tossy type III could provide sufficient stability to allow early functional rehabilitation, and to decrease the rate of complications.

[Complications of surgical treatment for femoral intertrochanteric fractures using dynamic hip screw].

OBJECTIVE: To investigate the complications of surgical treatments for femoral intertrochateric fractures using dynamic hip screw (DHS). METHODS: From Jan. 2002 to Dec. 2007, sixty-nine patients with intertrochanteric fractures were treated by dynamic hip screw fixation included 27 males and 42 females,with an average age of 72.9 years ranging from 53 to 96 years. According to Evans classification there were 10 cases in type I ,21 in type II, 22 in type III, and 16 in type IV, of which 51 patients (73.9%) suffered from systematic diseases preoperatively. RESULTS: Fifty-seven patients were followed up for 8 to 70 months (41 months on average). Four patients died, 17 cases occurrenced systematic complications postoperatively. Internal fixation related complications occurred in 12 patients. There were 8 cases with mechanical failure of DHS including 4 of screw loosen,3 of cutting-out of device through femoral head and neck and 1 of plate breakage. Five patients had a coxa vara, and delayed union occurred in 4 patients. CONCLUSION: Unstable fracture pattern produced high percentage of mechanical failure. In such cases DHS should not be the first choice for treatment. The appropriate treatment should be in relation to pre-operative fracture stability and osteoporosis.

[Analysis of fracture conditions and therapeutic experiences of earthquake casualties].

OBJECTIVE: To analyze the fracture conditions of earthquake casualties, summarize the therapeutic experiences and explore the frontier treatment model. METHODS: The clinical data of spot treatment of fracture patients in Wenchun earthquake were collected and analyzed to observe the therapeutic effects of operative patients and to verify the rationality of the cooperated remedy model of unified military and civilian hospitals. RESULTS: Among 236 fracture patients admitted in hospital, there were patients with extremities fractures in 81.3%, multiple fractures in 11.4% and open fractures in 10.6%. In all 55 patients underwent surgical treatment,the functional improvement rate was 65.5% and no infection or amputation happened. Supported by psychological aids, all patients were coordinated with treatment and the short-term outcome was parallel with that of ordinary fracture cases. CONCLUSION: The general conditions of patients should be paid more attention to during the treatment procedure of fractures because of the great quantity of casualties and severe traumatic conditions in Wenchun earthquake. The cooperated remedy model of unified military and civilian hospitals should be regarded as a new sanitation service practice with certain advantages. Psychological aids can provide strong support for the patients' postoperative rehabilitation.