舾装件贴装工艺优化

探讨了船舶大型跨分段合拢缝的舾装件贴装方式及存在的问题,提出了跨分段合拢缝处舾装件在工艺方面和设计方面的贴装优化方案,解决了现场舾装件贴装不规范和指示说明不明确的问题。

Effect of extrusion on the microstructure and mechanical properties of a low-alloyed Mg-2Zn-0.8Sr-0.2Ca matrix composite reinforced by TiC nano-particles

A low-alloyed Mg-2Zn-0.8Sr-0.2Ca matrix composite reinforced by TiC nano-particles was successfully prepared by semi-solid stirring under the assistance of ultrasonic,and then the as-cast composite was hot extruded.The results indicated that the volume fraction of dynamical recrystallization and the recrystallized grain size have a certain decline at lower extrusion temperature or rate.The finest grain size of~0.30μm is obtained in the sample extruded at 200℃ and 0.1 mm/s.The as-extruded sample displays a strong basal texture intensity,and the basal texture intensity increases to 5.937 mud while the extrusion temperature increases from 200 to 240℃.The ultra-high mechanical properties(ultimate tensile strength of 480.2 MPa,yield strength of 462 MPa)are obtained after extrusion at 200℃ with a rate of 0.1 mm/s.Among all strengthening mechanisms for the present composite,the grain refinement contributes the most to the increase in strength.A mixture of cleavage facets and dimples were observed in the fracture surfaces of three as-extruded nanocomposites,which explain a mix of brittle-ductile fracture way of the samples.

半潜船艉部挂舵筒可调节搭架工装设计

为解决在船舶艉部挂舵筒处的搭架工装无法有效贴合船体外板,局部搭架高度不可调节而导致繁锁搭架的问题。设计了一种可调节搭架工装,可以灵活调节搭架高度,减少了现场架子使用数量,提高了船舶建造搭架效率。

A dual-role of SARS-CoV-2 nucleocapsid protein in regulating innate immune response

The recently emerged severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which is the causative agent of ongoing global pan demic of COVID-19,may trigger imm uno suppression in the early stage and overactive immune resp onse in the late stage of infection;However,the un derlying mecha nisms are not well understood.Here we dem on strated that the SARS-CoV-2 nucleocapsid(N)protein dually regulated innate immune responses,i.e.,the low-dose N protein suppressed type I interferon(IFN-I)signaling and inflammatory cytokines,whereas high-dose N protein promoted IFN-I signaling and inflammatory cytokines.Mechanistically,the SARS-CoV-2 N protein dually regulated the phosphorylation and nuclear translocation of IRF3,STAT1,and STAT2.Additi on ally,low-dose N protein combined with TRIM25 could suppress the ubiquitination and activatio n of retinoic acidinducible gene I(RIG-I).Our findings revealed a regulatory mechanism of innate immune responses by the SARS-CoV-2 N protein,which would contribute to understanding the pathogenesis of SARS-CoV-2 and other SARS-like coronaviruses,and development of more effective strategies for controlling COVID-19.

Controlling exciton-exciton annihilation in WSe_(2) bilayers via interlayer twist

The twist angle between two van der Waals coupled monolayers has emerged as a new and powerful degree of freedom for engineering physical properties of semiconductor homo-and hetero-bilayers.While the interlayer twist has shown prominent effect on electronic and optical properties of transition metal dichalcogenide(TMD)bilayers,it remains unclear how it could be used to manipulate the exciton dynamics,especially exciton-exciton annihilation(EEA)process which is the dominant energy loss channel in TMDs under moderate to high exciton density due to strong Coulomb interaction.Herein,we show that the twist angle in TMD bilayers can act as an effective knob to control the EEA process.Specifically,EEA rate constant increases from 1° twisted WSe_(2) bilayers(0.026 cm^(2)/s)by more than twice to 32° twisted bilayers(0.053 cm2/s)and then drops again in 60° twisted bilayers(0.019 cm^(2)/s).This twist-angle dependence can be attributed to the energy difference between indirect and direct excitons arising from the interlayer interaction.Our work opens up the possibility of artificially managing the exciton dynamics in TMD materials for optoelectronic applications via interlayer twist angle.

First Fatal Infection and Phylodynamic Analysis of Severe Fever with Thrombocytopenia Syndrome Virus in Jilin Province,Northeastern China

Dear Editor,Severe fever with thrombocytopenia syndrome(SFTS),caused by SFTS virus(SFTSV)in the genus Banyangvirus of the family Phenuiviridae,is an emerging tick-borne viral zoonosis(Liu et al.2014).Typical clinical symptoms of SFTS include fever,headache,thrombocytopenia,and leukocytopenia(Yu et al.2011).Since SFTSV was identified in 2009,it has been found in more than 20 provinces in China and is closely related to strains from Japan and South Korea(Kim et al.2013;Takahashi et al.2014).

A case report of autochthonous Q fever with pneumonia and hepatitis in northeastern China

There are only a few case reports of Q fever caused by Coxiella burnetii in China,despite the nature as a ubiquitous zoonotic disease worldwide.In the northeast part of China,a 52-year-old male presented with fever,cough,shortness of breath,and sputum production,accompanied by headache,dizziness,chill,myalgia,and arthralgia.Chest computed tomography images showed pneumonia accompanied by bilateral scattered infiltrates and localized upper-lobe emphysema.The abnormal liver function was indicated by the increased levels of alanine aminotransferase and aspartate aminotransferase.Through high-throughput sequencing and molecular detection,Coxiella burnetii was positive in the patient's blood specimens.After treatment with moxifloxacin hydrochloride and vidarabine monophosphate for 12 days,the patient completely recovered.To our knowledge,this was the first reported case of Q fever with pneumonia and hepatitis in this country.