Effect of hot isostatic pressing processing parameters on microstructure and properties of Ti60 high temperature titanium alloy

Hot isostatic pressing parameters are critical to Ti60 high temperature titanium alloy castings which have wide application perspective in aerospace.In order to obtain optimal processing parameters,the effects of hot isostatic pressing parameters on defects,composition uniformity,microstructure and mechanical properties of Ti60 cast high temperature titanium alloy were investigated in detail.Results show that increasing temperature and pressure of hot isostatic pressing can reduce defects,especially,the internal defects are substantially eliminated when the temperature exceeds 920℃or the pressure exceeds 125 MPa.The higher temperature and pressure can improve the microstructure uniformity.Besides,the higher pressure can promote the composition uniformity.With the temperature increases from 880℃to 960℃,α-laths are coarsened.But with increasing pressure,the grain size of prior-βphase,the widths ofα-laths andα-colony are reduced.The tensile strength of Ti60 alloy is 949 MPa,yield strength is 827 MPa,and the elongation is 11%when the hot isostatic pressing parameters are 960℃/125 MPa/2 h,which exhibits the best match between the strength and plasticity.

Human CD4- CD8- Invariant Natural Killer T Cells Promote IgG Secretion from B Cells Stimulated by Cross-Linking of Their Antigen Receptors

Immunoglobulin (Ig) M production can be induced by the interaction of thymus-independent type-2 (TI-2) antigen (Ag) with B cell Ag receptors (BCRs) without the involvement of conventional T cells;for IgG production through the same process, however, a second signal is required. Previous studies have reported that invariant natural killer T (iNKT) cells may be responsible for the second signal involved in IgG production. In the present study, we addressed whether human iNKT cells could participate in the production of Ig against TI-2 Ag in vitro. Two major distinct subsets of human iNKT cells, CD4+ CD8β- (CD4) and CD4- CD8β- [double negative (DN)] cells, were generated from peripheral blood monocytes from a healthy volunteer. BCR engagement, triggered by anti-IgM antibody stimulation, examined here as a model of BCR engagement triggered by TI-2 Ag, induced abundant IgM production by B cells. Both CD4 and DN iNKT cells reduced IgM production and conversely enhanced IgG production in a dose-dependent manner. In addition, IgG production by CD19+CD27- (naïve) and CD19+CD27+ (memory) B cells was predominantly promoted by DNiNKT cells rather than CD4 iNKT cells;nevertheless, IgM production by both B cell subsets was similarly reduced by either subset of iNKT cells. These results suggest that the DN iNKT subsets may preferentially promote Ig class switching by B cells upon stimulation with TI-2 Ag.

QTL detection for growth traits in Pinus elliottii var. elliottii and P. caribaea var. hondurensis

Quantitative trait locus （QTL） detection was carried out for growth traits in 122 F1 progenies of Pinus elliottiivar. elliottii （PEE） x tR caribaea var. hondurensis （PCH） hybrid. The PCH male parent linkage map contained 108 mark- ers in 16 linkage groups, while the PEE female parent contained 93 markers in 19 linkage groups. Sequence-related amplified polymorphism （SRAP）, microsatellite （SSR）, expressed sequence tag polymorphism （ESTP） and inter-simple sequence repeat （ISSR） were selected from an existing linkage map. Growth traits investigated were height at age five （HT05） and six years （HT06）, diameter at breast height at age five （DBH05） and six years （DBH06） and annual growth from age five to six years of height （AGHT） and diameter at breast height （AGDBH）. KruskaI-Wallis and interval mapping approaches were used to estimate levels of significance, the number of QTLs, the percentage of the phenotypic varia- tion explained by each of QTLs and their positions on the genetic linkage maps. Twenty six QTLs with significance levels p 〈 0.05 were detected on the parental maps for the six growth traits, which explained more than 15% of the phenotypic variation, suggesting an existence of major-effect genes. Several QTLs had the pleiotropy controlling more than one sin- gle growth trait. Overall, the proportion of phenotypic variation explained by QTLs ranged from 5.9% to 40.6% for HT05 and HT06, from 6.6% to 42.0% for DBH05 and DBH06 and from 5.8% to 22.3% for AGHT and AGDBH. The results from this study provide a basis for marker-aided selection （MAS） in PEE x PCH hybrids.

Design and Evaluation of a Differential Accelerometer for Drop-Tower Equivalence Principle Test with Rotating Masses

A differential accelerometer comprising of two rotating masses made of the same material is proposed for drop tower-based free-fall testing of the spin-spin force between the rotating mass and the Earth. The measurement is performed by placing the two concentric masses of very different momenta in a vacuum drop capsule which is falling freely in the Earth＇s gravitational field. A nonzero output of the differential aeeelerometer is an indication of possible violation of new equivalence principle （NEP）. We present the conceptual design of a modified free-fall NEP experiment which can be performed at the Belting drop tower. Design and evaluation of the differential accelerometer with a hybrid electrostatic/magnetic suspension system are presented to accommodate for operation on ground and drop-tower tests. Details specific to the measurement uncertainty are discussed to yield an NEP test accuracy of 7.2×10^-9.

A Virtual Reality Platform for Context-Dependent Cognitive Research in

Animal survival necessitates adaptive behav-iors in volatile environmental contexts.Virtual reality(VR)technology is instrumental to study the neural mechanisms underlying behaviors modulated by environmental con-text by simulating the real world with maximized control of contextual elements.Yet current VR tools for rodents have limited flexibility and performance(e.g.,frame rate)for context-dependent cognitive research.Here,we describe a high-performance VR platform with which to study con-textual behaviors immersed in editable virtual contexts.This platform was assembled from modular hardware and custom-written software with flexibility and upgradability.Using this platform,we trained mice to perform context-dependent cognitive tasks with rules ranging from discrim-ination to delayed-sample-to-match while recording from thousands of hippocampal place cells.By precise manipula-tions of context elements,we found that the context recogni-tion was intact with partial context elements,but impaired by exchanges of context elements.Collectively,our work establishes a configurable VR platform with which to investigate context-dependent cognition with large-scale neural recording.

The Content of Statistical Requirements for Authors in Biomedical Research Journals

Background：Robust statistical designing,sound statistical analysis,and standardized presentation are important to enhance the quality and transparency of biomedical research.This systematic review was conducted to summarize the statistical reporting requirements introduced by biomedical research journals with an impact factor of 10 or above so that researchers are able to give statistical issues＇ serious considerations not only at the stage of data analysis but also at the stage of methodological design.Methods：Detailed statistical instructions for authors were downloaded from the homepage of each of the included journals or obtained from the editors directly via email.Then,we described the types and numbers of statistical guidelines introduced by different press groups.Items of statistical reporting guideline as well as particular requirements were summarized in frequency,which were grouped into design,method of analysis,and presentation,respectively.Finally,updated statistical guidelines and particular requirements for improvement were summed up.Results：Totally,21 of 23 press groups introduced at least one statistical guideline.More than half of press groups can update their statistical instruction for authors gradually relative to issues of new statistical reporting guidelines.In addition,16 press groups,covering 44 journals,address particular statistical requirements.The most of the particular requirements focused on the performance of statistical analysis and transparency in statistical reporting,including ＂address issues relevant to research design,including participant flow diagram,eligibility criteria,and sample size estimation,＂ and ＂statistical methods and the reasons.＂ Conclusions：Statistical requirements for authors are becoming increasingly perfected.Statistical requirements for authors remind researchers that they should make sufficient consideration not only in regards to statistical methods during the research design,but also standardized statistical reporting,which would be beneficial in providing stronger evidence and making a greater critical appraisal of evidence more accessible.