Flt-3 ligand increases microchimerism but can prevent the therapeutic effect of donor bone marrow in transiently immunosuppressed cardiac allograft recipients

C3H (H2k) mice received 50 x 10(6) B10 (H2b) bone marrow (BM) cells either alone or with flt-3 ligand (FL) (10 microg/day), tacrolimus (2 mg/kg/day), or both agents for 7 days. Donor MHC class II+ (IAb+) cells were quantitated in spleens by immunohistochemical analysis, and donor class II DNA detected in BM by PCR. Donor cells were rare in the BM alone and BM + FL groups, whereas there was a substantial increase in chimerism in the BM + tacrolimus group. Addition of FL to BM + tacrolimus led to a further eightfold increase in donor cells and enhanced donor DNA compared with the BM + tacrolimus group. This increase in donor cells was almost 500-fold compared with BM alone. C3H recipients of B10 heart allografts given perioperative B10 BM and tacrolimus (days 0-13) exhibited a markedly extended median graft survival time (MST, 42 days) compared with those given tacrolimus alone (MST, 22 days). Addition of FL (10 microg/day; 7 days) to BM + tacrolimus prevented the beneficial effect of donor BM (MST, 18 days). BM alone or BM + FL resulted in uniform early heart graft failure (MST < 8 days). Functional studies revealed maximal antidonor MLR and CTL activities in the BM- and BM + FL-treated groups, with minimal activity in the tacrolimus-treated groups. Thus, dramatic growth factor-induced increases in chimerism achieved under cover of immunosuppression may result in augmented antidonor T cell reactivity and reduced graft survival after immunosuppressive drug withdrawal. With FL, this may reflect striking augmentation of immunostimulatory dendritic cells.     

Do additive manufactured parts deserve better?

Additive manufacturing of metallic components is regarded as one of the more exciting developments in engineering. The combined attractions of near net shape, tailored composition, and geometry optimisation have led to much interest in the various processes used and a drive to improve the mechanical properties to match those of wrought parts. In this paper, we reflect on the apparent lack of ambition in optimising the structural integrity of parts made using these new manufacturing processes. The current research focus seems to be either on largely irrelevant static properties, or on quantifying the fatigue response in a way that would be familiar to engineers in the 19^th Century. Given the work on the role of microstructure and fatigue, which dates back to Ewing and Humphrey in 1903 reaching its zenith in the 1980s and 90s with Keith Miller in the vanguard, and recent developments in both imaging technologies and sophisticated numerical modelling, all the elements are in place for a much more rigorous, and ultimately more fruitful, approach to understand the structural integrity of additive manufactured components.     

Green synthesis of silver nanoparticles using Cyathea nilgirensis Holttum and their cytotoxic and phytotoxic potentials

The present study aimed at synthesizing silver nanoparticles (AgNPs) from the aqueous extract of C. nilgirensis and their biopotential using cytotoxicity and phytotoxicity. On mixing the aqueous extract with 1?mM AgNO₃ solution, the color changes from pale yellow to yellowish brown color. The absorption spectra of yellowish brown nanoparticle showed a plasmon absorption band with a maximum of 3.806 and 1.028 abs in 311 and 440?nm, respectively. The Fourier transform infrared spectroscopy (FTIR) spectra confirmed that phenolic compounds have stronger ability to bind with metal, indicating that phenolics could possibly form metal nanoparticles to prevent agglomeration and thereby stabilize the medium. The size of AgNP is found to be in the 45.0–74.0?nm range. The Energy-dispersive X-ray (EDX) spectra analysis revealed the presence of a strong Ag peak. The results indicated that C. nilgirensis aqueous extract was found efficient for the synthesis of AgNPs.     

Influence of Superheat on Microstructure and Mechanical Properties of Ductile Cu47.5Zr47.5Al5 Bulk Metallic Glass-Matrix Composite

Generally bulk metallic glasses (BMGs) posses very less ductility and toughness at room temperature. Over the recent past years to improve up on these properties in many alloy system BMG composites have been developed. It was also reported that Cu_47.5Zr_47.5Al₅ BMG composite shows a very high strength together with an extensive work hardening-like behavior of large ductility around 18%. In this study, the influence of superheat on microstructure and the resulting mechanical properties in Cu_47.5Zr_47.5Al₅ bulk metallic glass-matrix composite alloy has been studied. The Cu_47.5Zr_47.5Al₅ melt solidifies into a composite microstructure consisting of crystalline precipitates embedded in an amorphous matrix. The crystalline phase consists of B2 CuZr (cubic primitive with CsCl structure) with a small amount of monoclinic CuZr martensitic structure embedded in an amorphous matrix. The volume fraction of crystalline phases varies with melting current as well as position along the length of the as-cast rod, depending on the local cooling condition. The volume fraction and the distribution of the crystalline precipitates are heterogeneous in the amorphous matrix. Room temperature uniaxial compression tests revealed high yield strength ranging from 796 to 1900 MPa depending upon the volume fraction of the crystalline phases present. The presence of the dendritic B2 CuZr significantly improved the ductility. The BMG composites show a pronounced plastic strain up to 14% for the higher volume fraction of crystalline phase.     

Effect of microstructure on the tensile strength of Ti6Al4V specimens manufactured using additive manufacturing electron beam process

Electron beam melting additive manufacturing (AM) process has been developed for the manufacture of Ti6Al4V parts for the aerospace industry. In the AM research team from Airbus Group, this technology is being evaluated with a view to production of flight hardware. During the evaluation of the process, the microstructure variation as a function of geometry was studied. A distinctive microstructure was observed up to 0.5?mm from of part surface (the skin layer) and the thickness of the α-plate spacing varied depending on the thickness of the parts being produced. With the purpose of quantifying the influence of the grain thickness and the mechanical performance of the material, cylinders with nine different diameters (6 up to 40?mm diameter) were manufactured with 80?mm height. The microstructure characterisation showed how the α-plate spacing changed from thin to thick structures and the influence of grain size on tensile strength was quantified.     

Microstructure and Mechanical Properties of Wire and Arc Additive Manufactured Ti-6Al-4V

Wire and arc additive manufacturing (WAAM) is a novel manufacturing technique in which large metal components can be fabricated layer by layer. In this study, the macrostructure, microstructure, and mechanical properties of a Ti-6Al-4V alloy after WAAM deposition have been investigated. The macrostructure of the arc-deposited Ti-6Al-4V was characterized by epitaxial growth of large columnar prior-β grains up through the deposited layers, while the microstructure consisted of fine Widmanstätten α in the upper deposited layers and a banded coarsened Widmanstätten lamella α in the lower layers. This structure developed due to the repeated rapid heating and cooling thermal cycling that occurs during the WAAM process. The average yield and ultimate tensile strengths of the as-deposited material were found to be slightly lower than those for a forged Ti-6Al-4V bar (MIL-T 9047); however, the ductility was similar and, importantly, the mean fatigue life was significantly higher. A small number of WAAM specimens exhibited early fatigue failure, which can be attributed to the rare occurrence of gas pores formed during deposition.     

Road Map for In Situ Grown Binder-Free MOFs and Their Derivatives as Freestanding Electrodes for Supercapacitors

Among several electrocatalysts for energy storage purposes including supercapacitors, metal–organic frameworks (MOFs), and their derivatives have spurred wide spread interest owing to their structural merits, multifariousness with tailor-made functionalities and tunable pore sizes. The electrochemical performance of supercapacitors can be further enhanced using in situ grown MOFs and their derivatives, eliminating the role of insulating binders whose “dead mass” contribution hampers the device capability otherwise. The expulsion of binders not only ensures better adhesion of catalyst material with the current collector but also facilitates the transport of electron and electrolyte ions and remedy cycle performance deterioration with better chemical stability. This review systematically summarizes different kinds of metal–ligand combinations for in situ grown MOFs and derivatives, preparation techniques, modification strategies, properties, and charge transport mechanisms as freestanding electrode materials in determining the performance of supercapacitors. In the end, the review also highlights potential promises, challenges, and state-of-the-art advancement in the rational design of electrodes to overcome the bottlenecks and to improve the capability of MOFs in energy storage applications.