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The study introduced a true triaxial testing apparatus for conducting time-dependent experiments on hard rocks under high stress. The apparatus consists of two-rigid loading platens to apply the maximum and intermediate principal stresses, and a flexible loading system with which to apply the minimum principal stress, under constant-temperature control. It includes a simple sample-installation system, an acoustic emission acquisition system, data acquisition system, and a software interface. The novel apparatus overcomes the long-term eccentric loading problem faced when testing rock samples using a biaxial double-closed-loop servo-control mode. In addition, using an integrated structural design, the stiffness of the apparatus was increased, which was conducive to improving the data precision obtained in small-scale deformation experiments involving hard, stiff, or strong, rock samples. It also provides the possibility of studying the post-peak time-dependent behaviours of hard rocks under high stress. To verify the advantages of this apparatus and investigate the influence of intermediate principal stress on the time-dependent behaviour of hard rock, this study demonstrated the experimental methods and results for pre- and post-peak time-dependent of hard rock under true triaxial compression. The experimental results showed that intermediate principal stress exerted a significant influence on the time-dependent behaviour, and long-term deformation and strength, of hard rocks: post-peak fractured rocks still exhibited a certain time-dependent strength. The results also validated the reliability of this true triaxial time-dependent apparatus. [ABSTRACT FROM AUTHOR]

Nanocellulose has attracted attention from the scientific community due to its biodegradability and unique physiochemical characteristics. However, the production of high-quality nanocellulose is still limited by the high cost of chemical usage, purification, and energy consumption. In this work, we proposed a catalytic aerobic process for preparing aldehyde-functionalized cellulose nanocrystals by oxidizing cellulose in a triisopropoxy vanadium (VO(OiPr)3)/O2 system and investigated the mechanism of selective oxidation of cellulose in this system. Well-dispersed cellulose nanocrystals with a diameter of approximately 100 nm and an aldehyde content of 0.425 mmol g−1 were obtained under the conditions of 120 °C, 4 MPa O2 pressure, and a 12 h reaction time. The catalyst employed in the oxidation process still retained high activity after being reused four times. This research presents an alternative strategy for the preparation of cellulose nanocrystals with limited chemical usage, which would contribute to the development of environmentally friendly and cost-effective processes for nanocellulose production. [ABSTRACT FROM AUTHOR]

Objective: To report the early results of castor device, a kind of unibody single-branched stent graft, in the treatment of type B aortic dissection (TBAD) involving the LSA.Methods: From April 2013 to February 2014, 21 patients with TBADs underwent TEVAR with LSA revascularization by unibody single-branched stent grafts. Three patients with penetrating aortic ulcers in the aortic arch received additional reconstruction of left common carotid artery with chimney technique. Follow-up evaluations were conducted with computed tomography angiography (CTA) at 6, 12 months and annually after that.Results: All of the proximal entry tears were completely excluded. Good patency of the grafts was found in all cases. A small type I endoleak occurred in one patient during the procedure. Perioperative mortality is null, and there was no occurrence of serious complications. All patients completed the follow-up except one lost contact after discharge. One death occurred within 6 months after the operation, resulting from myocardial infarction, considered unrelated to the stent implantation. No endoleak occurred during follow-up. One compression of a chimney stent and one twist of side branch graft of castor were observed in 2 different patients, respectively. In other cases, CTA scans showed good patency of both the branched and chimney grafts. Two patients had partial thrombosis of the false lumen during follow-up. In other patients, complete thrombosis in the false lumen in thoracic aorta was revealed.Conclusion: The single-branched stent graft was safe and efficient in the 1-year follow-up. Further studies are required to determine its long-term outcomes. [ABSTRACT FROM AUTHOR]

This paper investigates the drying and wetting soil water retention curves (SWRCs) of statically compacted lime-stabilised London Clay specimens. A series of tests were performed using the contact filter paper method, pressure plate apparatus and a suction-controlled triaxial system incorporating the axis translation technique. These investigated the water retention of the soil under different boundary and stress-state conditions and simultaneously determined the volume change in the soil during drying and wetting. Factors relevant to the lime treatment of soils, such as curing period and method (air vs. water curing), were also considered. Finally, the hysteresis of the SWRC of the chemically treated soil (for which there appears to be a lack of information in the international literature) was investigated. The results showed that the treatment with lime increased the volumetric stability but reduced the water retention ability due to a more open structure enabled by the flocculation and chemical bonding effects. Curing period and method effect appears to be small. Hysteresis was noted to some degree in all instances. [ABSTRACT FROM AUTHOR]

Two-dimensional materials/bulk semiconductor vertical van der Waals heterojunction are of great importance for high performance photodetector. However, their actualization are still impeded by their relatively narrow response range and large amounts of interfacial defects. Herein, in light of the excellent optoelectronic properties of WSe 2 and Ge, we design a kind of self-powered vertical WSe 2 /AlO x /Ge heterojunction photodetector with MXene top electrode by simply stacking Ti 3 C 2 T x MXene and WSe 2 thin film on the AlO x /Ge substrate. The device enables an ultra-broadband spectral response from 405 nm to 3800 nm (mid-wave infrared light) because of the plasmon-induced hot electrons in the Ti 3 C 2 T x MXene film. Also, the device proves the distinguished photodetection performance in terms of a large responsivity of ∼ 1088 mA/W, a high specific detectivity of ∼ 1.17 × 1012 Jones at 980 nm, and a fast response time of 43/63 μs. The vertical stacking structure, the introduction of passivation layer and MXene electrode are considered to be new strategies of designing heterojunction for ultra-broadband, low-power consumption and high performance next-generation photodetector. • A kind of self-powered vertical WSe 2 /AlO x /Ge heterojunction photodetector with MXene top electrode was designed. • The photodetector enables an ultra-broadband spectral response from 405 to 3800 nm because of the plasmon-induced hot electrons in the Ti 3 C 2 T x MXene film. • The device proves the distinguished performance in terms of a large responsivity of ∼ 1088 mA/W, a high specific detectivity of ∼ 1.17 × 1012 Jones at 980 nm, and a fast response time of 43/63 μs. [ABSTRACT FROM AUTHOR]

The postdeposition annealing (PDA)-treated charge-trap flash memory capacitor with stacked Zr0.46Si0.54O2/Al2O3 charge-trapping layer flanked by a SiO2 tunneling oxide and an Al2O3 blocking oxide was fabricated and investigated. It is observed that the memory capacitor exhibits prominent memory characteristics with large memory windows 12.8 V in a ±10 V gate sweeping voltage range, faster program/erase speed, and good data-retention characteristics even at 125 °C compared to a single charge-trapping layer (Zr0.46Si0.54O2, Zr0.79Si0.21O2, and Zr0.46Al1.08O2.54). The quantum wells and introduced interfacial traps of the stacked trapping layer regulate the storage and loss behavior of charges, and jointly contribute to the improved memory characteristics. Hence, the memory capacitor with a stacked trapping layer is a promising candidate in future nonvolatile charge-trap memory device design and application. [ABSTRACT FROM AUTHOR]

A facile method was used to oxidize p-type Zinc Selenide (ZnSe) nanowires into n-type Zinc Oxide (ZnO) through a 700 °C annealing process in air. Single crystal ZnSe nanowires, with a hole concentration of 0.805 × 10 cm and a negative photoconductivity, were oxidized into polycrystalline ZnO nanowires with an electron concentration of 4.88 × 10 cm and a positive photoconductivity. Additionally, both the as-synthesized ZnSe nanowires and the post-oxidized ZnO nanowires presented excellent optoelectronic properties. This method can be used to construct radial p-n junctions or other nano-devices based on a single NW through a regioselective oxidation process. [ABSTRACT FROM AUTHOR]