Automatic Modification of Local Drilling Holes via Double Pre-Assembly Holes

Manufacturing accuracy, especially position accuracy of fastener holes, directly affects service life and security of aircraft. The traditional modification has poor robustness, while the modification based on laser tracker costs too much. To improve the relative position accuracy of aircraft assembly drilling, and ensure the hole-edge distance requirement, a method was presented to modify the coordinates of drilling holes. Based on online inspecting two positions of pre-assembly holes and their theoretical coordinates, the spatial coordinate transformation matrix of modification could be calculated. Thus the straight drilling holes could be modified. The method improves relative position accuracy of drilling on simple structure effectively. And it reduces the requirement of absolute position accuracy and the cost of position modification. And the process technician also can use this method to decide the position accuracy of different pre-assembly holes based on the accuracy requirement of assembly holes.

Virtual pre-assembly for large steel structures based on BIM, PLP algorithm, and 3D measurement

The current physical pre-assembly method of large steel structures is time consuming and costly and requires large sites. Thus, the pre-assembly of large steel structures in a virtual way, starting from building information modeling (BIM), is an interesting alternative to the physical one. In this study, an innovative method for virtual pre-assembly is proposed on the basis of BIM, plane-line-point algorithm, and 3D measurement. This method determines the optimal analytical least squares of the various built components. The technique verifies the feasibility of the steel structure assembly and the fulfillment of the design geometries, starting from the real data obtained by an accurate metric survey of the fabricated steel elements. The method is applied to a real case, and obtained results largely satisfy the prefixed research objectives. Suggestions to improve the proposed method are also discussed.

Superhigh intrinsic proton conductivity in densely carboxylic covalent organic framework

Herein,we developed for the first time two carboxylic acid based intrinsic proton conductors(COOHCOF-1 and COOH-COF-2)via pre-assembly approach.The obtained COOH-COF-1 and COOH-COF-2 not only show outstanding chemical and thermal stabilities,but also exhibit superhigh intrinsic proton conductive behaviors.Especially,the intrinsic proton conductivity of COOH-COF-2 is up to 2.6×10^(−3) S/cm at 353 K and 98%RH,which is the highest value among all the reported acid functionalized COFs.This work lights up the way for the rational design of functional COFs with remarkably intrinsic proton conducting performance and related practical applications.

Selectively enhancing radiosensitivity of cancer cells via in situ enzyme-instructed peptide self-assembly

The radiotherapy modulators used in clinic have disadvantages of high toxicity and low selectivity.For the first time,we used the in situ enzyme-instructed self-assembly(EISA)of a peptide derivative(Nap-GDFDFpYSV)to selectively enhance the sensitivity of cancer cells with high alkaline phosphatase(ALP)expression to ionizing radiation(IR).Compared with the in vitro pre-assembled control formed by the same molecule,assemblies formed by in situ EISA in cells greatly sensitized the ALPhigh-expressing cancer cells to y-rays,with a remarkable sensitizer enhancement ratio.Our results indicated that the enhancement was a result of fixing DNA damage,arresting cell cycles and inducing cell apoptosis.Interestingly,in vitro pre-formed assemblies mainly localized in the lysosomes after incubating with cells,while the assemblies formed via in situ EISA scattered in the cell cytosol.The accumulation of these molecules in cells could not be inhibited by endocytosis inhibitors.We believed that this molecule entered cancer cells by diffusion and then in situ self-assembled to form nanofibers under the catalysis of endogenous ALP.This study provides a successful example to utilize intracellular in situ EISA of small molecules to develop selective tumor radiosensitizers.