Rod-shaped SnS nanocrystals were synthesized by a facile solvothermal method, which were then compacted by a cold isostatic pressing and rapid annealing process. Two-order higher carrier mobility was ...achieved in the corresponding bulk samples, leading to over 200% enhancement of thermoelectric figure of merit.
Rod-shaped SnS nanocrystals synthesized by solvothermal method enhances thermoelectric figure of merit due to higher carrier mobility.
AgBiSe
2
and AgSbSe
2
, two typical examples of Te-free I-V-VI
2
chalcogenides, are drawing much attention due to their promising thermoelectric performance. Both compounds were synthesized
via
...melting and consolidated by spark plasma sintering. The role of annealing on the transport properties of polymorphous AgBiSe
2
and monophase AgSbSe
2
was studied. Annealing has a greater impact on AgBiSe
2
than AgSbSe
2
, which is ascribed to the temperature dependent phase transition of AgBiSe
2
. Unannealed AgBiSe
2
shows p-n switching, but annealed AgBiSe
2
exhibits n-type semiconducting behavior over the whole measurement temperature range. By performing high-temperature Hall measurements, we attribute this intriguing variation to the change in the amount of Ag vacancies and mid-temperature rhombohedral phase after annealing. Both AgBiSe
2
and AgSbSe
2
exhibit low thermal conductivity values, which are ∼0.40-0.50 W m
−1
K
−1
for AgSbSe
2
and ∼0.45-0.70 W m
−1
K
−1
for AgBiSe
2
, respectively. The maximum
ZT
value of AgBiSe
2
is enhanced from 0.18 to 0.21 after annealing. Pristine AgSbSe
2
presents a
ZT
value as high as 0.60 at 623 K, although slight deterioration emerges after annealing.
Annealing treatment has different impact on the transport properties of polymorphous AgBiSe
2
and monophase AgSbSe
2
.
Microstructure engineering is an effective strategy to reduce lattice thermal conductivity (κl ) and enhance the thermoelectric figure of merit (zT). Through a new process based on ...melt-centrifugation to squeeze out excess eutectic liquid, microstructure modulation is realized to manipulate the formation of dislocations and clean grain boundaries, resulting in a porous network with a platelet structure. In this way, phonon transport is strongly disrupted by a combination of porosity, pore surfaces/junctions, grain boundaries, and lattice dislocations. These collectively result in a ≈60% reduction of κl compared to zone melted ingot, while the charge carriers remain relatively mobile across the liquid-fused grains. This porous material displays a zT value of 1.2, which is higher than fully dense conventional zone melted ingots and hot pressed (Bi,Sb)2 Te3 alloys. A segmented leg of melt-centrifuged Bi0.5 Sb1.5 Te3 and Bi0.3 Sb1.7 Te3 could produce a high device ZT exceeding 1.0 over the whole temperature range of 323-523 K and an efficiency up to 9%. The present work demonstrates a method for synthesizing high-efficiency porous thermoelectric materials through an unconventional melt-centrifugation technique.
Cu
3
SbSe
3
, a compound with an ultralow thermal conductivity, has been predicted as a promising thermoelectric material, but relevant experimental results are inadequate. In this work we studied ...the high-temperature thermoelectric properties of this ternary chalcogenide. An extremely low thermal conductivity was observed and a glass-like behavior was seen above an order-disorder transition. Possible mechanisms causing such an ultralow thermal conductivity were discussed concerning the disorder of Cu atoms. With a large band gap of ∼0.95 eV obtained by an optical absorption edge measurement, Cu
3
SbSe
3
was found to be a nondegenerate p-type semiconductor, different from previous reports. A maximum
zT
of ∼0.25 was obtained at 650 K for Cu
3
SbSe
3
, which is much higher than the previously reported values, but this compound was considered inferior to Cu
3
SbSe
4
in its thermoelectric performance by comparing some key physical parameters.
Cu
3
SbSe
3
characterized by ultralow thermal conductivity is a wide-gap, nondegenerate semiconductor with a large effective mass and deformation potential, yielding
zT
max
= 0.25.
Cu sub(3)SbSe sub(3), a compound with an ultralow thermal conductivity, has been predicted as a promising thermoelectric material, but relevant experimental results are inadequate. In this work we ...studied the high-temperature thermoelectric properties of this ternary chalcogenide. An extremely low thermal conductivity was observed and a glass-like behavior was seen above an order-disorder transition. Possible mechanisms causing such an ultralow thermal conductivity were discussed concerning the disorder of Cu atoms. With a large band gap of similar to 0.95 eV obtained by an optical absorption edge measurement, Cu sub(3)SbSe sub(3) was found to be a nondegenerate p-type semiconductor, different from previous reports. A maximum zT of similar to 0.25 was obtained at 650 K for Cu sub(3)SbSe sub(3), which is much higher than the previously reported values, but this compound was considered inferior to Cu sub(3)SbSe sub(4) in its thermoelectric performance by comparing some key physical parameters.
AIM: To investigate the risk factors and surgical outcomes for spontaneous rupture of Barcelona Clinic Liver Cancer(BCLC) stages A and B hepatocellular carcinoma(HCC).METHODS: From April 2002 to ...November 2006, 92 consecutive patients with spontaneous rupture of BCLC stage A or B HCC undergoing hepatic resection were included in a case group. A control arm of 184 cases(1:2 ratio) was chosen by matching the age, sex, BCLC stage and time of admission among the 2904 consecutive patients with non-ruptured HCC undergoing hepatic resection. Histological confirmation of HCC was available for all patients and ruptured HCC was confirmed by focal discontinuity of the tumor with surrounding perihepatic hematoma observed intraoperatively. Patients with microvascular thrombus in the hepatic vein branches were excluded from the study. Clinical data and survival time were collected and analysed.RESULTS: Sixteen patients were excluded from the study based on exclusion criteria, of whom 3 were in the case group and 13 in the control group. Compared with the control group, more patients in the case group had underlying diseases of hypertension(10.1% vs 3.5%, P = 0.030) and liver cirrhosis(82.0% vs 57.9%, P < 0.001). Tumors in 67(75.3%) patients in the case group were located in segments Ⅱ, Ⅲ and Ⅵ, and the figure in the control group was also 67(39.7%)(P < 0.001). On multivariate analysis, hypertension(HR = 7.38, 95%CI: 1.91-28.58, P = 0.004), liver cirrhosis(HR = 6.04, 95%CI: 2.83-12.88, P < 0.001) and tumor location in segments Ⅱ, Ⅲ and Ⅵ(HR = 5.03, 95%CI: 2.70-6.37, P < 0.001) were predictive for spontaneous rupture of HCC. In the case group, the median survival time and median disease-free survival time were 12 mo(range: 1-78 mo) and 4 mo(range: 0-78 mo), respectively. The 1-, 3- and 5-year overall survival rates and disease-free survival rates were 66.3%, 23.4% and 10.1%, and 57.0%, 16.8% and 4.5%, respectively. Only radical resection remained predictive for overall survival(HR = 0.32, 95%CI: 0.08-0.61, P = 0.015) and disease-free survival(HR = 0.12, 95%CI: 0.01-0.73, P = 0.002).CONCLUSION: Tumor location, hypertension and liver cirrhosis are associated with spontaneous rupture of HCC. One-stage hepatectomy should be recommended to patients with BCLC stages A and B disease.
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