Search

A cesium bismuth germanate, Cs2Bi2O(Ge2O7) (CBGO), was synthesized by a traditional high-temperature solid-state reaction. Its structure features a 3D network composed of a 1D chains composed of Bi2O8 dimers that are further bridged by Ge2O7 dimers, forming tunnels of seven member rings (MRs) that are filled by the Cs+ cations. CBGO exhibits extraordinary larger second harmonic generation (SHG) response of about 13.7 times that of KDP (KH2PO4) under 1064 nm laser radiation and 1.1 times that of KTP (KTiOPO4) under 2.05 mu m laser radiation, which is the highest among all of the metal germanates reported so far. CBGO possesses a moderate birefringence (0.073 at 1064 nm) and is phase matchable. Furthermore, CBGO melts congruently and exhibits high thermal stability.

A new ultraviolet nonlinear optical material, namely LiHgPO4, was synthesized using the mild hydrothermal method. The structure of LiHgPO4 features novel double layers constructed by severely distorted HgO6 octahedra and PO4 tetrahedra, which are further interconnected by LiO4 tetrahedra to form a three-dimensional structure. LiHgPO4 exhibits a very strong second harmonic generation (SHG) response of 11.0 times that of KH2PO4 and a relatively large birefringence (0.068 at 1064 nm) among the reported SHG-active phosphates. Theoretical calculations revealed that the introduction of the Hg2+ in a highly distorted HgO6 octahedral geometry is crucial to produce the strong SHG response and large birefringence.

Two new barium polyiodate compounds in the alkali-earth system, namely, HBa2.5(IO3)6(I2O5) (Fdd2) and HBa(IO3)(I4O11) (P1) have been obtained through hydrothermal reaction. Interestingly, the stru...

Herein, two new acentric borogermanates, namely, Ca2GeB2O7 and Ca1.78Cd0.22GeB2O7, were obtained by combining BO4 with a GeO4 tetrahedron. The structures of the isomeric Ca2GeB2O7 and Ca1.78Cd0.22GeB2O7 feature two-dimensional (2D) [GeB2O7] layers parallel to the ab plane in which a GeO4 tetrahedron corner is shared with four [B2O7] units; the divalent cations are filled in between layers. Ca2GeB2O7 and Ca1.78Cd0.22GeB2O7 display second-harmonic generation (SHG) intensity around 0.4 and 0.6 times that of KH2PO4 (KDP), respectively. Ca2GeB2O7 possesses a short UV absorption edge (about 194 nm). Thermal stability measurements show that Ca2GeB2O7 melts congruently at high temperatures, whereas Ca1.78Cd0.22GeB2O7 melts incongruently and becomes amorphous at high temperatures. Moreover, measurements of the optical properties as well as theoretical calculations of these two compounds were conducted.

By using hydrofluoric acid as a solubilizer, the first alkali-metal niobium iodate and an alkali-earth metal niobium iodate, i.e. (H3O)HCs2Nb(IO3)9 and SrNbO(IO3)5, have been obtained. An obvious cation-controlled polarity shift is observed in the Ae/A-Nb5+-IO3 system. (H3O)HCs2Nb(IO3)9 gives a strong second harmonic generation (SHG) signal about 6 times that of KH2PO4 (KDP), making it a promising nonlinear optical (NLO) material.

Bo Wu,1,* Bing Wan,2,* Shu-Ting Lu,1 Kai Deng,3 Xiao-Qi Li,1 Bao-Lin Wu,1 Yu-Shuang Li,1 Ru-Fang Liao,1 Shi-Wen Huang,3 Hai-Bo Xu1,2 1Department of Radiology, Zhongnan Hospital of Wuhan University, 2Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, 3Department of Chemistry, Key Laboratory of Biomedical Polymers, Ministry of Education, Wuhan University, Wuhan, People’s Republic of China *These authors contributed equally to this work Abstract: The major challenge in current clinic contrast agents (CAs) and chemotherapy is the poor tumor selectivity and response. Based on the self-quench property of IR820 at high concentrations, and different contrast effect ability of Gd-DOTA between inner and outer of liposome, we developed “bomb-like” light-triggered CAs (LTCAs) for enhanced CT/MRI/FI multimodal imaging, which can improve the signal-to-noise ratio of tumor tissue specifically. IR820, Iohexol and Gd-chelates were firstly encapsulated into the thermal-sensitive nanocarrier with a high concentration. This will result in protection and fluorescence quenching. Then, the release of CAs was triggered by near-infrared (NIR) light laser irradiation, which will lead to fluorescence and MRI activation and enable imaging of inflammation. In vitro and in vivo experiments demonstrated that LTCAs with 808nm laser irradiation have shorter T1 relaxation time in MRI and stronger intensity in FI compared to those without irradiation. Additionally, due to the high photothermal conversion efficiency of IR820, the injection of LTCAs was demonstrated to completely inhibit C6 tumor growth in nude mice up to 17 days after NIR laser irradiation. The results indicate that the LTCAs can serve as a promising platform for NIR-activated multimodal imaging and photothermal therapy. Keywords: light triggered, near-infrared light, tumor-specific, multimodal imaging, photothermal therapy, contrast agents

A cesium bismuth germanate, Cs

A new ultraviolet nonlinear optical material, namely LiHgPO

By using hydrofluoric acid as a solubilizer, the first alkali-metal niobium iodate and an alkali-earth metal niobium iodate, i.e. (H3O)HCs2Nb(IO3)9 and SrNbO(IO3)5, have been obtained. An obvious cation-controlled polarity shift is observed in the Ae/A-Nb5+-IO3 system. (H3O)HCs2Nb(IO3)9 gives a strong second harmonic generation (SHG) signal about 6 times that of KH2PO4 (KDP), making it a promising nonlinear optical (NLO) material.

In this work, the tensile properties of AZ31 Mg alloy deformed by multi-directional forging (MDF) were investigated at room temperature. And the enhanced mechanical properties of yield strength of 93 MPa, ultimate tensile strength (UTS) of 253 MPa and elongation of 29% were achieved. It is discovered that the MDF deformation makes the crystallographic orientation of original as-cast microstructure randomization, providing the condition for the following twinning during tensile deformation. In addition, the original fine grains and continuously refined grains can enhance the strength by restricting the growth of grains and motion of dislocations.

In this paper, a light-weight equimolar MgCaAlLiCu high entropy alloy (HEA) is reported. The microstructure of the alloy cast in copper mould was composed mainly of a solid solution phase with tetragonal symmetry structure, presenting the high-entropy alloy nature. The alloy exhibited high fracture strength of 910 MPa during the room-temperature compression process. Based on thermodynamic calculation, the underlying reason for the formation of the solid solution in the MgCaAlLiCu alloy is given.

the microstuctures and orientations changing of hot extrusion AZ31 magnesium alloy were obtained by equal channel angular pressing (ECAP). After the ECAP samples annealed, the dynamic anistropy of AZ31 alloy in different impacting directions were given by dynamic compressing in HSPB system. The results showed that with pression passes increasing, the grains were refined more obviously and {0002} texture component increased and concentrated in the center of the pole figure. The maxmium reduction under impacting direction (ID) parelleled to extrusion direction (ED) is larger than that of ID // ND during dynamic compressing, and there was a obvious strain softing in the strain-stress curves. However, the dramatic strain hardening and higher yield strength appeared in the stress-strain figure when ID parelleled to ND. In addition, the reasons for mechanical anistropy of AZ31 alloy were discussed in a way of grains orientationes changing.

As a good experimental platform for multi-agent system, Robot Soccer World Cup (RoboCup) has become a hot topic of artificial intelligence. This paper reviewed the technical characteristics of related robots in Simulation, Small Size, Middle Size and Humanoid It introduced the intelligent control algorithms such as Agent structure, Kalman filtering, self-positioning of robots and ZMP stability judgment.

the hot extruded AZ31 magnesium alloy which has basal texture was impacted along different direction and different fracture mode appeared. Under different impacted direction, the basal slip, prismatic slip, pyramidal slip, compression twin and tension twin have different critical resolved shearing stress (CRSS) and Schmid factor. Then different deformation modes were activated and resulted to different fracture modes.

The annealed AZ31 magnesium alloy with 400°C and 1.5hour was selected and compressed under different deformation amount. The orientation and microstructure were investigated too. The results shown that the twinning type and amount changed the orientation of new grain after compressed largely. The tension twinning made the orientation deviated form TD to ED in the {10-10} pole figure, but contraction and double twinning mad the orientation concentrated in the TD.

The strain-controlled fatigue tests on extruded AZ31B magnesium alloy were conducted under the uniaxial loading with strain ratio Rε=-∞, frequency of 0.1 Hz and strain amplitude of 2% at room temperature. The cyclic hardening behavior was investigated. It was found that, during the low cycle fatigue (LCF) process, as the number of cycles increases, the stress amplitude increases corresponding to the decrease of the plastic strain amplitude. The development of dislocation density can be described as the function of the number of fatigue cycles, and the behavior can be explained well based on the dislocation density development model.

In this paper, Al matrix composites reinforced with Al-Ti intermetallics/Ti metal compound spherical agents were successfully fabricated through powder metallurgy way. Al-Ti intermetallic including Al3Ti and TiAl phases are main reinforcements and inner Ti metal could not only play reinforce role but also reduce the crack sensitivity of Al-Ti intermetallics. This kind of reinforcements bonded strongly with Al matrix. As expected, the resultant composites exhibit promising mechanical properties at ambient temperature. And the mechanical property could be improved through regulating the relative thickness of the Al-Ti intermetallics and Ti metal layers.

Uni-axial tensile test was conducted at room temperature on a weak texture AZ31B magnesium alloy at different strain rate, from 2.8×10-5s-1 to 1.1×10-1s-1. The mechanical behavior was investigated. It was found that as strain rate is increased, flat character of the stress-strain curves can be found and {10-12} tension twinning is responsible for this phenomenon. The sample exhibites a brittle fracture at 1.1×10-1s-1 strain rate while exhibites a ductile fracture character at 2.8×10-5s-1 strain rate.

In order to obtain fine-microstructure magnesium alloys with superior mechanical properties, AZ61 alloy was processed by friction stir processing(FSP) combined with rapid heat sink. It is found that ultrafine-grained microstructure with average size less than 300 nm is observed in the resultant AZ61 alloy. The mean microhardness of the ultra-fine region reaches Hv120-130, two times higher than that of AZ61 substrate. All these results demonstrate clearly that under a cooling rate high enough, ultra-fine structure in AZ61 alloy with superior mechanical properties can be produced by one pass FSP via dynamic recrystallization.

It is well known that inadequate strength at elevated temperatures and low fracture toughness at ambient temperatures are the major deficiencies preventing the B2 aluminide NiAl as an advanced structural material used at high temperatures. [1–3] In order to promote its practical use, a promising NiAl based alloy system, i.e., the IP alloy reinforced by Laves phase has been developed. [4–10] The common characteristics of these alloys are that all of them exhibit higher melting points (about 1460°C), lower densities (6.20 ∼ 6.35 g/cm 3 ), higher thermal conductivity and excellent oxidation resistance compared to the Ni-based superalloys. Furthermore, these alloys can be processed by a series of different production routes, which may be used for property variation within a wide range. [8–10] However, the previous relevant studies proved that the alloys prepared by conventional ingot casting showed coarse-grained microstructure and then exhibited serious brittle fracture at ambient temperatures. On the other hand, the alloys processed by powder metallurgy or mechanical heat treatment with finer microstructure usually improved room temperature brittleness but seriously lowered yield stresses at high temperatures. [6,7] Therefore, for these alloys, to find an efficient way to optimize mechanical properties is necessary to promote their practical use. It is suggested that the mechanical properties of these alloys depend sensitively on the grain size of NiAl matrix and distribution of strengthening Laves phase which is controlled by processing parameters, such as temperature, time and cooling rate. [7] Rapid solidification to produce bulk metallic alloys is known for a long time to result in refined microstructure, extended solubility, reduced microsegregation, and formation of metastable phases. Injection casting, as a popular rapidly solidified technique to fabricate bulk amorphous alloys, can provide relatively high cooling rates of about 10 2 ∼ 10 3 Ks –1 that is significantly higher than 10 –1 ∼ 10 –2 Ks –1 for conventional casting. [11] Sun et al. [12] and Dai et al. [13] have investigated the effects of refined eutectic interlamellar spacing and grain size on the mechanical properties of the Ti-based alloys, and found that the optimized microstructure induced by Cu mold casting was responsible for the improved room-temperature mechanical properties. Recently, Huai et al reported that the mechanical properties of eutectic NiAl/Cr(Mo, Hf) alloy could be optimized by rapid solidification process, i.e. suction casting. [14] However, the suction casting process could not provide enough high cooling rate as injection casting. Accordingly, in the current study, an IP alloy with the composition of NiAl-Cr/Nb alloy was chosen and prepared by injection casting, and its microstructural morphology and mechanical properties were investigated. Due to the limited amount of sample material available, compression tests were performed only. The compression testing results demonstrate that the resultant alloy exhibits improved compressive ductility and yield strength at room temperature as compared with that of the same alloy prepared by conventional ingot casting. Meanwhile, the yielding strength of resultant alloy is slightly lowered at high temperatures. The test results are quite reproducible.

Robust output-feedback controller against various perturbations is proposed for satellite formation keeping. The mixed H2/Hinfin controller with regional pole placement constraints is designed based on linear Hill's equations. The mixed H2/Hinfin controller takes into account both the disturbance rejection aspects and the LQG aspects. In addition, the closed-loop poles can be forced into some sector of the stable half-plane to obtain well-damped transient responses. The problem is reduced to a convex optimization involving linear matrix inequalities (LMIs), so it can be solved efficiently. Extensive simulation studies were conducted for the validation of the proposed robust controller using Matlabtrade. The simulation results demonstrate that the developed multi-objective control system is robust stable and optimal in the sense of H2 norm, and has good steady-state and dynamic performances against various disturbances for the satellite formation system