In this article, the electron beam welding of the Cu alloy （ QCrO. 8） with Ti alloy （TC4） sheet was processed and the joint microstructure as well as the welding process were studied. The results show that brittle reaction layer which was mainly composed of TiCu, Ti2Cu, Ti2Cu3 and TiCu2formed at the weld fusion line, regardless of welding on the middle or on the Cu side. The mechanical properties of the joint were severely deteriorated by the layer that tensile strength was only 89. 4 MPa for welding on the Cu side. The microstructure of the joint was improved with pure nickel as filler metal for the electron beam welding. The weld was mainly composed of solid solution. Intermetallic compound phase decreased signifwantly in fusion line compared with the joint without filler metal. The mechanical properties of the joint were obviously improved that the average tensile strength was 205.2 MPa and the bending strength was 413.3 MPa with O. 5 mm offset of electron beam on the Cu side.
Visual analytics has been widely studied in the past decade. One key to make visual analytics practical for both research and industrial applications is the appropriate definition and implementation of the visual analytics pipeline which provides effective abstractions for designing and implementing visual analytics systems. In this paper we review the previous work on visual analytics pipelines and individual modules from multiple perspectives： data, visualization, model and knowledge. In each module we discuss various representations and descriptions of pipelines inside the module, and compare the commonalities and the differences among them.
We probe the universality of acceleration scale a_(0) in Milgrom's modified Newtonian dynamics(MOND)using the recently released rotation curve data from SPARC galaxies.We divide the SPARC data into different subsamples according to the morphological types of galaxies,and fit the rotation curve data of each subsample with the theoretical prediction of MOND.MOND involves an arbitrary interpolation function which connects the Newtonian region and the MOND region.Here we consider five different interpolation functions that are widely discussed in the literature.It is shown that the best-fitting a_(0) significantly depends on the interpolation functions.For a specific interpolation function, a_(0) also depends on the morphological types of galaxies,implying that a_(0) may be not a universal constant.Introducing a dipole correction to a_(0) can significantly improve the fits.The dipole directions for four of the five interpolation functions point towards an approximately consistent direction,but a_(0) still varies for different interpolation functions.
The clustered regularly interspaced short palindromic repeat （CRISPR） system has emerged as the revolu- tionary platform for DNA targeting. This system uses a site-specific RNA guide to direct a CRISPR effector （e.g., Cas9 and Cpfl） to a DNA target. Here, we elaborate a general strategy to simultaneously express multiple guide RNAs （gRNA） and CRISPR RNAs （crRNA） from introns of Cas9 and Cpfl. This method utilizes the endogenous tRNA processing system or crRNA processing activity of Cpfl to cleave the spliced intron that contains tRNA-gRNA polycistron or crRNA-crRNA array. We demonstrated that the tRNA-gRNA intron is able to fuse with Cas9 as one gene. Such a hybrid gene could be expressed using one polymerase II promoter, and exhibited high efficiency and robustness in simultaneously targeting multiple sites. We also implemented this strategy in Cpfl-mediated genome editing using intronic tRNA-crRNA and crRNA-crRNA arrays. Interestingly, hybrid genes containing Cpfl and intronic crRNA array exhibited remarkably increased efficiency compared with the conventional Cpfl vectors. Taken together, this study presents a method to express CRISPR reagents from one hybrid gene to increase genome-editing efficiency and capacity. Owing to its simplicity and versatility, this method could be broadly used to develop sophisticated CRISPR tools in eukaryotes.
The hardfacing alloys with different concentrations of titanium were deposited on carbon steel substrates by shielded metal arc welding, and the effect of titanium content on the microstructure characteristics of the hardfacing alloys was investigated. The wear resistance test of the hardfacing alloys was carried out by using a slurry rubber wheel abrasion test machine, and the wear behaviour was also studied. The results indicate that the addition of titanium can effectively promote the precipitation of the complex carbides of Nb and Ti due to the prior precipitation of titanium carbide which acts as nucleation sites for complex carbides. With the increase of titanium content, the wear resistance of the hardfacing alloys is increased gradually resulting from the refinement of microstructure and dispersive distribution of fine carbide precipitates. And the wear mechanism is mainly minimum plastic deformation with interrupted grooves due to the strengthening and protecting effects of carbide precipitates.
Glycogen storage disease(GSD)is a rare autosomal recessive disease by abnormal accumulation of intracellular glycogen.1 Mutations in genes encoding G-6-P or G-6-Pase lead to dysfunction of the body's glycogen metabolism.Without adequate metabolic treatment,patients with GSD can die during infancy or childhood from severe hypoglycemia and acidosis.The patient's symptoms generally achieve remission during adolescence,except in rare cases when cirrhosis of the liver or myopathy occurs.Once GSD is identified in adults,the patients are often accompanied by many complications,such as fasting hypoglycemia.
Maohui YinLei ChangPing JiangZhiyong YangZhonglin ZhangWanyu ZhangZhisu Liu
We propose a characteristic finite element evolutionary type convection-diffusion optimal control discretization of problems. Non- divergence-free velocity fields and bilateral inequality control constraints are handled. Then some residual type a posteriori error estimates are analyzed for the approximations of the control, the state, and the adjoint state. Based on the derived error estimators, we use them as error indicators in developing efficient multi-set adaptive meshes characteristic finite element algorithm for such optimal control problems. Finally, one numerical example is given to check the feasibility and validity of multi-set adaptive meshes refinements.
