ALBERT

Description: In this study, a combination of Al–12Si and Al–20Si (Al–(12-20)Si) alloys was fabricated by selective laser melting (SLM) as a result of increased component requirements such as geometrical complexity and high dimensional accuracy. The microstructure and mechanical properties of the SLM Al–(12-20)Si in as-produced as well as in heat-treated conditions were investigated. The Al–(12-20)Si interface was in the as-built condition and it gradually became blurry until it disappeared after heat treatment at 673 K for 6 h. This Al–(12-20)Si bi-material displayed excellent mechanical properties. The hardness of the Al–20Si alloy side was significantly higher than that of the Al–12Si alloy side and the disparity between both sides gradually decreased and tended to be consistent after heat treatment at 673 K for 6 h. The tensile strength and elongation of the Al–(12-20Si) bi-material lies in between the Al–12Si and Al–20Si alloys and fracture occurs in the Al–20Si side. The present results provide new insights into the fabrication of bi-materials using SLM.

Description: The 2016 Mw 7.8 Kaikoura earthquake triggered widespread slow slip events (SSEs) in the northern Hikurangi subduction zone, providing a unique opportunity to study the mechanism of dynamic triggering of SSEs. Here we simulate SSEs near Gisborne, New Zealand, in the framework of rate-and-state friction. Low effective normal stress (~0.4 MPa) on the shallow subduction interface is needed to reproduce the observed repeating, spontaneous SSEs. Dynamic stress perturbations from the Kaikoura mainshock are adequate to trigger SSEs with characteristics similar to observation. SSE propensity to dynamic triggering mainly depends on the timing of perturbation with respect to the SSE cycle and the maximum Coulomb stress change. Once the perturbation amplitude exceeds an initial threshold, prolonged stress perturbations tend to decrease the triggering threshold hence promote dynamic triggering of SSEs. Therefore, shallow SSEs are more likely to be dynamically triggered than their deep counterparts because of enhanced stress perturbation (magnitude and duration) from the sedimentary wedge. ©2018. American Geophysical Union. All Rights Reserved.

Description: Reducing the cumulative error is a crucial task in simultaneous localization and mapping (SLAM). Usually, Loop Closure Detection (LCD) is exploited to accomplish this work for SLAM and robot navigation. With a fast and accurate loop detection, it can significantly improve global localization stability and reduce mapping errors. However, the LCD task based on point cloud still has some problems, such as over-reliance on high-resolution sensors, and poor detection efficiency and accuracy. Therefore, in this paper, we propose a novel and fast global LCD method using a low-cost 16 beam Lidar based on “Simplified Structure”. Firstly, we extract the “Simplified Structure” from the indoor point cloud, classify them into two levels, and manage the “Simplified Structure” hierarchically according to its structure salience. The “Simplified Structure” has simple feature geometry and can be exploited to capture the indoor stable structures. Secondly, we analyze the point cloud registration suitability with a pre-match, and present a hierarchical matching strategy with multiple geometric constraints in Euclidean Space to match two scans. Finally, we construct a multi-state loop evaluation model for a multi-level structure to determine whether the two candidate scans are a loop. In fact, our method also provides a transformation for point cloud registration with “Simplified Structure” when a loop is detected successfully. Experiments are carried out on three types of indoor environment. A 16 beam Lidar is used to collect data. The experimental results demonstrate that our method can detect global loop closures efficiently and accurately. The average global LCD precision, accuracy and negative are approximately 0.90, 0.96, and 0.97, respectively.

Description: This study developed a new cable-less seismograph system, which can transmit seismic data in real-time and automatically perform high-precision differential self-positioning. Combining the ZigBee technology with the high-precision differential positioning module, this new seismograph system utilized the wireless personal area network (WPAN) and real-time kinematic (RTK) technologies to improve its on-site performances and to make the field quality control (QC) and self-positioning possible. With the advantages of low-cost, good scalability, and good compatibility, the proposed new cable-less seismograph system can improve the field working efficiency and data processing capability. It has potential applications in noise seismology and mobile seismic monitoring.

Description: High-frequency sensors can monitor water quality with high temporal resolution and without environmental influence. However, sensors for detecting key water quality parameters, such as total nitrogen(TN), total phosphorus(TP), and other water environmental parameters, are either not yet available or have attracted limited usage. By using a large number of high-frequency sensor and manual monitoring data, this study establishes regression equations that measure high-frequency sensor and key water quality parameters through multiple regression analysis. Results show that a high-frequency sensor can quickly and accurately estimate dynamic key water quality parameters by evaluating seven water quality parameters. An evaluation of the flux of four chemical parameters further proves that the multi-parameter sensor can efficiently estimate the key water quality parameters. However, due to the different optical properties and ecological bases of these parameters, the high-frequency sensor shows a better prediction performance for chemical parameters than for physical and biological parameters. Nevertheless, these results indicate that combining high-frequency sensor monitoring with regression equations can provide real-time and accurate water quality information that can meet the needs in water environment management and realize early warning functions.

Description: Background Internal tandem duplication of FMS-like tyrosine kinase 3 (FLT3-ITD) mutations have been reported in 20%-30% of patients with acute myeloid leukemia (AML). FLT3-ITD-positive AML patients have an inferior survival, primarily due to lower complete remission (CR) rate and higher relapse rate. Although allogeneic hematopoietic stem cell transplantation (allo-HSCT) improves the outcomes of some FLT3-ITD-positive AML, a significant number will suffer disease recurrence after allo-HSCT. Sorafenib, an inhibitor of multiple kinases including FLT3, has shown promising activity in FLT3-ITD-positive AML. Recent studies have shown that sorafenib monotherapy or in combination with chemotherapy are effective in attaining CR, but they do not have significant improvement in relapse. Currently, prophylactic use of sorafenib after allo-HSCT has been rarely reported, and whether it can improve outcomes of FLT3-ITD-positive AML remains unclear. Methods A total of 18 patients with FLT3-ITD-positive AML undergoing allo-HSCT from January 2012 to March 2014 at our single institute were enrolled in this retrospective study. Seven patients were in first CR at the time of transplantation and all received standard conditioning: busulfan 4 mg/kg/d P.O. or 3.2 mg/kg/d I.V. (on days -7 to -4), cyclophosphamide 60 mg/kg/d (on days -3, -2). Eleven patients were not in CR (NR) at the time of transplantation and all received intensified conditioning: fludarabine 30 mg/m2/d (on days -10 to -6), cytarabine 2.0 g/m2/d (on days -10 to -6), total body irradiation 4.5 Gy/d (on days -5, -4), cyclophosphamide 60 mg/kg/d (on days -3, -2), etoposide 15 mg/kg/d (on days -3, -2). Sorafenib was used from day 30 to 180 post-transplantation. The initial dose of sorafenib was 400 mg orally twice daily and was adjusted in case of suspected toxicity or resistance (dose range, 200-800 mg daily). Results Of the 18 patients, 7 received prophylactic sorafenib, including 3 in CR and 4 in NR pre-transplantation; 11 did not receive prophylactic sorafenib, including 4 in CR and 7 in NR pre-transplantation. There were no significant differences in disease status pre-transplantation, HLA-typing and the source of donors between the two groups (all P〉0.05). The eleven patients in NR at the time of transplantation all achieved CR and had complete chimerism by day +30 post-transplantation. With a median follow up of 433 (range, 124-765) days post-transplantation, 7 patients with prophylactic sorafenib all had no recurrence and survived. Of the 11 patients without prophylactic sorafenib, 5 experienced leukemia relapse at a median time of 92 (range, 49 to 335) days post-transplantation, including hematologic in 4 and central nervous system (CNS) in 1. The patient with CNS relapse achieved CR after radiotherapy and donor lymphocyte infusion (DLI), and was still alive now. Of the 4 patients with hematologic relapse, one abandoned treatment and 3 received treatment, including sorafenib combined with chemotherapy and DLI. Two of the three patients achieved short CR after treatment and finally all of them died of relapse within half a year. With a median follow up of 343 (range, 135-863) days post-transplantation, 6 patients survived and 5 died in the 11 patients without prophylactic sorafenib. Causes of death included leukemia relapse (n=4) and chronic graft-versus-host disease (n=1). The 1-year cumulative incidence of leukemia relapse was 0.0% and 50.9% in patients with and without prophylactic sorafenib (P=0.046). The 1-year overall and disease-free survival were 100.0% and 100.0% in patients with prophylactic sorafenib, compared with 49.9% and 42.4% in those without prophylactic sorafenib (P=0.066, P=0.028). The main side effect of sorafenib was rash, and none of patients experienced bone marrow suppression. Of the 10 patients with sorafenib treatment, 6 had hand-foot skin reaction and/or rash. Anti-allergy therapy was ineffective, and glucocorticoid was usually required. In 4 of the 6 patients, the skin rash covered gradually after reducing the dose of sorafenib and the use of glucocorticoid. Other two patients even required drug discontinuation, but sorafenib was tolerated after the reuse. Conclusions Early prophylactic use of sorafenib has an acceptable toxicity profile and could reduce relapse of FLT3-ITD-positive AML. Disclosures Liu: It was supported by Natural Science Foundation of Guangdong Province (S2012010009299); the project of health collaborative innovation of Guangzhou city (201400000003-4, 201400000003-1): Research Funding; It was supported by National Natural Science Foundation of China (81270647, 81300445, 81200388); National High Technology Research and Development Program of China (863 Program) (2011AA020105); National Public Health Grand Research Foundation (201202017): Research Funding; It was supported by the Technology Plan of Guangdong Province of China (2012B031800403); the project of the Zhujiang Science & Technology Star of Guangzhou city (2013027): Research Funding. Xuan:It was supported by National Natural Science Foundation of China (81270647, 81300445, 81200388); National High Technology Research and Development Program of China (863 Program) (2011AA020105): Research Funding.