The lattice misfit between the body-centered cubic α-Fe matrix and the B2-ordered NiAl-type β′ precipitates is a parameter of significant importance in controlling the creep resistance of ...precipitate-strengthened ferritic steels. However, the measurement of the lattice misfit is complicated due to the fact that the fundamental reflections of α and β′ phases almost completely overlap. In this study, neutron diffraction is used to determine the lattice parameters of these two phases in a Fe–18.9 Al–9.8 Cr–13 Ni–1.8 Mo (atomic percent, at.%) alloy as a function of temperature. The accuracy of the measurement at room temperature is verified by high-energy synchrotron X-ray diffraction. The comparison between these two techniques is discussed in terms of the difference in superlattice intensity. Furthermore, using the phase compositions determined by atom probe tomography, models are proposed to predict the lattice parameters of both phases at room temperature as a function of their compositions. The results are in very good agreement with those obtained experimentally.
More than 21 million prescriptions for warfarin are written yearly in the U.S. Despite its importance, warfarin's target, vitamin K epoxide reductase (VKOR), has resisted purification since its ...identification in 1972. Here, we report its purification and reconstitution. HPC4, a calcium-specific antibody that recognizes a 12-aa tag, was used to purify and identify VKOR. Partial reconstitution is achieved on the column by washing with 0.4% dioleoylphosphatidylcholine/0.4% deoxycholate. Activity is completely recovered by dialysis against a buffer containing a reducing agent but lacking dioleoylphosphatidylcholine/deoxycholate. Removal of detergent from the eluted proteins apparently facilitates liposome formation. Purified recombinant VKOR with tag is ≈21 kDa, as expected; fully active; and >93% pure. The concentration of warfarin for 50% inhibition is the same for purified protein and microsomes. It has been reported that VKOR is a multisubunit enzyme. Our results, however, suggest that a single peptide can accomplish both the conversion of vitamin K epoxide to vitamin K and vitamin K to reduced vitamin K. This purification will allow further characterization of VKOR in relation to other components of the vitamin K cycle and should facilitate its structural determination. purification reconstitution membrane protein
In the present work, the sintering behaviour of HA particles prepared via the wet precipitation method (HAp) and wet mechanochemical technique (HAwm) was investigated. The sintering behaviour of a ...commercial HA powder (HAc) was also studied for comparison purpose. All the three powders were characterised in terms of particle size, Ca/P ratio and crystal size. Green samples were prepared and sintered in air at temperatures ranging from 1000°C to 1400°C. The sintered bodies were studied in terms of the phase stability, relative density, Young's modulus, Vickers hardness, fracture toughness and grain size. The results indicated that HAwm samples suffered phase decomposition while the HAp and HAc sintered samples showed no phase disruption throughout the temperature range employed. The HAp samples exhibited the overall best densification and properties when compared to the HAc and HAwm samples. Furthermore, the results showed that mechanical properties of sintered samples were governed by both the bulk density and the grain size.
The efficiency of the container port industry has been variously studied utilising either Data Envelopment Analysis (DEA) or Stochastic Frontier Analysis (SFA). Given the strengths and weaknesses ...associated with these two approaches, the efficiency estimates and scale properties derived from these analyses are not always convincing. This paper applies both approaches to the same set of container port data for the world’s largest container ports and compares the results obtained. A high degree of correlation is found between the efficiency estimates derived from all the models applied, suggesting that results are relatively robust to the DEA models applied or the distributional assumptions under SFA. High levels of technical efficiency are associated with scale, greater private-sector participation and with transhipment as opposed to gateway ports. In analysing the implications of the results for management and policy makers, a number of shortcomings of applying a cross-sectional approach to an industry characterised by significant, lumpy and risky investments are identified and the potential benefits of a dynamic analysis, based on panel data, are enumerated.
The sinterability of nanocrystalline hydroxyapatite (HA) particles by microwave sintering was compared with conventional pressureless sintering. The results revealed that microwave heating was ...effective in producing a useful HA body in a very short sintering cycle without disrupting the HA phase stability. The maximum hardness of 7.21
GPa and 6.38
GPa was obtained for HA sintered at 1050
°C by the conventional method and 1150
°C by microwave sintering, respectively. The maximum fracture toughness measured for the microwave-sintered and conventional-sintered HA was 1.45
MPam
1/2 at 1050
°C and 1.22
MPam
1/2 at 1000
°C, respectively. Although the relative density of microwave-sintered HA was slightly lower than the conventional-sintered HA throughout the sintering regime employed, taking into account of the heating and soaking periods, the time taken by microwave sintering to achieve a relative density of 96.5% was about 3% of the time consumed for samples sintered by the conventional heating. Microwave heating was found to be an effective technique to produce a useful HA body for clinical applications without causing grain coarsening.
A scheme is proposed for preparing Greenberger-Horne-Zeilinger (GHZ) states by Lyapunov control based on quantum Zeno dynamics. The advantage of our method is that we use the square pulse to instead ...of the time-varying control fields and optimal the control processing which is shorter than the stimulated Raman adiabatic passage. The influence of cavity decay and spontaneous emission also be taken in account, the numerical simulation results show that it is immune to the cavity decay and emission of laser pulses. Additionally, we analyzed the preparation of the N-atom GHZ states with the same principle, which provides a scalable method for multi-qubit system in future.
► Study on the sintering behavior of hydroxyapatite prepared from different route. ► The effect of powder morphology on the properties of hydroxyapatite. ► Effect of sintering temperature on the ...grain size of HA produced by different route. ► Influence of sintering temperature on the fracture toughness and hardness of HA.
The sintering behavior of three different types of hydroxyapatite (HA) i.e. a commercial powder, HA(C), a synthesized powder by wet chemical precipitation method, HA(W) and a synthesized powder by mechanochemical method, HA(M) were investigated over the temperature range of 1000–1350
°C. It has been revealed that the sinterability and mechanical properties of the synthesized HA(W) was significantly higher than that of the HA(C) and HA(M). The optimum sintering temperature for the HA(W) samples was 1100
°C with the following properties being recorded: 99.8% relative density, Vickers hardness of 7.04
GPa and fracture toughness of 1.22
MPa
m
1/2. In contrast, the optimum sintering temperature for the HA(C) and HA(M) samples was 1300
°C with relative density of 98% and 95.5%, Vickers hardness of 5.47 GPa and 4.73
GPa, fracture toughness of 0.75
MPa
m
1/2 and 0.82
MPa
m
1/2 being measured. The present research showed that the wet chemical precipitation reaction was beneficial in producing a highly crystalline, high purity and single phase stoichiometric HA powder that is sinteractive particularly at low temperatures below 1100
°C.
The effect of rapid sintering by microwave heating on the properties of nanocrystalline hydroxyapatite (HA) bioceramic powder was studied. The starting high-purity nano HA crystals was synthesized ...using a wet chemical precipitation technique. The HA compacts were microwave-sintered over the temperature range 1000–1300
°C, using a rapid sintering schedule of 30
min for each temperature. Shrinkage of all compacts was uniform and the sintered material did not exhibit any cracks. XRD phase analysis indicated that the HA phase stability was not disrupted throughout the sintering regime employed. A relative density of 90–91% was attained for samples sintered at 1000
°C, whereas a higher relative density of above 96% and ∼98% was measured for HA sintered at 1100
°C and 1300
°C, respectively. The present work revealed that microwave heating was beneficial in preventing grain growth, particularly when sintered at temperatures <1200
°C, and coupled with improved mechanical properties, i.e., high fracture toughness of 1.45
MPa
m
1/2 and hardness of 6.38
GPa were measured for HA compacts sintered at 1050
°C and 1150
°C, respectively.
Overmoded slow-wave structure (SWS) plays an important role in developing the performance of Cerenkov oscillators at the millimeter-wave range. To investigate the effect of SWS size on power capacity ...as well as the problem of mode competition, the properties of the resonance modes in an overmoded SWS are focused on. Based on the mode selection method of enhancing the field of TM 01 and keeping the field of TM 02 mode steady, the output results for SWSs with various sizes are studied. Consequently, the size of SWS is reasonably determined, which can provide an effective beam-wave interaction process and the purified output mode. Moreover, the study on electron's movement in the diode area under the magnetic field of 0.8 T is conducted and then the value of the overmoded ratio α is finally confirmed as 2.5 to guarantee a lossless transportation of the electron beam. Verified by the particle-in-cell (PIC) simulations, the optimized structure shows a good capability of improving the output power and purifying the output mode.
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