Microstructural Modeling of Thermally-Driven β Grain Growth, Lamellae &Martensite in Ti-6Al-4V

The microstructural kinetics of β grain growth in the β field of a Ti-6Al-4V alloy was studied by a series of controlled heat treatments at constant temperature rates. Heating rates of 5°C/s, 50°C/s and 500°C/s were considered, stopping at different peak temperatures. The thickness evolution of martensitic needles and lamellar α laths, formed on cooling, was also investigated, by soaking the material above its β-transus temperature and cooling down at 5°C/s, 50°C/s, 100°C/s and 300°C/s till ambient temperature. Quantitative microstructural analyses were used to measure the particle dimensions. The β grain growth kinetics was reasonably well described by a modified Avrami equation. The thickness of α lamellae was a function of the cooling rate and the β grain dimension in which they nucleated. The martensite needle thickness was shown to be a function of the cooling rate to which the material was subjected.

Coexpression of CD163 and CD141 identifies human circulating IL-10-producing dendritic cells (DC-10)

Tolerogenic dendritic cells(DCs)are key players in maintaining immunological homeostasis,dampening immune responses,and promoting tolerance.DC-10,a tolerogenic population of human IL-10-producing DCs characterized by the expression of HLA-G and ILT4,play a pivotal role in promoting tolerance via T regulatory type 1(Tr1)cells.Thus far,the absence of markers that uniquely identify DC-10 has limited in vivo studies.By in vitro gene expression profiling of differentiated human DCs,we identified CD141 and CD163 as surface markers for DC-10.The coexpression of CD141 and CD163 in combination with CD14 and CD16 enables the ex vivo isolation of DC-10 from the peripheral blood.CD14+CD16+CD141+CD163+cells isolated from the peripheral blood of healthy subjects(ex vivo DC-10)produced spontaneously and upon activation of IL-10 and limited levels of IL-12.Moreover,in vitro stimulation of allogeneic naive CD4+T cells with ex vivo DC-10 induced the differentiation of alloantigen-specific CD49b+LAG-3+Tr1 cells.Finally,ex vivo DC-10 and in vitro generated DC-10 exhibited a similar transcriptional profile,which are characterized by an anti-inflammatory and pro-tolerogenic signature.These results provide new insights into the phenotype and molecular signature of DC-10 and highlight the tolerogenic properties of circulating DC-10.These findings open the opportunity to track DC-10 in vivo and to define their role in physiological and pathological settings.

Direct characterization of a nonlinear photonic circuit’s wave function with laser light

Integrated photonics is a leading platform for quantum technologies including nonclassical state generation1–4,demonstration of quantum computational complexity5 and secure quantum communications6.As photonic circuits grow in complexity,full quantum tomography becomes impractical,and therefore an efficient method for their characterization7,8 is essential.Here we propose and demonstrate a fast,reliable method for reconstructing the two-photon state produced by an arbitrary quadratically nonlinear optical circuit.By establishing a rigorous correspondence between the generated quantum state and classical sum-frequency generation measurements from laser light,we overcome the limitations of previous approaches for lossy multimode devices9,10.We applied this protocol to a multi-channel nonlinear waveguide network and measured a 99.28±0.31%fidelity between classical and quantum characterization.This technique enables fast and precise evaluation of nonlinear quantum photonic networks,a crucial step towards complex,largescale,device production.

Targeted heat treatment of additively manufactured Ti-6Al-4V for controlled formation of Bi-lamellar microstructures

Laser powder bed fusion(L-PBF)was utilized to produce specimens in Ti-6Al-4V,which were subjected to a bi-lamellar heat treatment,which produces microstructures consisting of primary α-lamellae and a fine secondary α-phase inside the inter-lamellar β-regions.The bi-lamellar microstructure was obtained as(i)a direct bi-lamellar heat treatment from the asbuilt condition or(ii)a bi-lamellar heat treatment preceded by a β-homogenization.For the bi-lamellar treatment with β-homogenization,cooling rates in the range 1-500 K/min were applied after homogenization in β-region followed by inter-critical annealing in the α+β region at various temperatures in the range 850-950℃.The microstructures were characterized using various microscopical techniques.Mechanical testing with Vickers hardness indentation and tensile testing was performed.The bi-lamellar microstructure was harder when compared to a soft fully lamellar microstructure,because of the presence of fine α-platelets inside the β-lamellae.Final low temperature ageing provided an additional hardness increase by precipitation hardening of the primary α-regions.The age hardened bi-lamellar microstructure shows a similar hardness as the very fine,as-built martensitic microstructure.The bi-lamellar microstructure has more favorable mechanical properties than the as-built condition,which has high strength,but poor ductility.After the bi-lamellar heat treatment,the elongation was improved by more than 250%.Due to the very high strength of the as-built condition,loss of tensile strength is unavoidable,resulting in a reduction of tensile strength of~18%.