Multi-material additive manufacturing of low sintering temperature Bi2Mo2O9 ceramics with Ag floating electrodes by selective laser burnout

Additive manufacturing (AM) of co-fired low temperature ceramics offers a unique route for fabrication of novel 3D radio frequency (RF) and microwave communication components, embedded electronics and sensors. This paper describes the first-ever direct 3D printing of low temperature co-fired ceramics/floating electrode 3D structures. Slurry-based AM and selective laser burnout (SLB) were used to fabricate bulk dielectric, Bi2Mo2O9 (BMO, sintering temperature = 620–650°C, εr = 38) with silver (Ag) internal floating electrodes. A printable BMO slurry was developed and the SLB optimised to improve edge definition and burn out the binder without damaging the ceramic. The SLB increased the green strength needed for shape retention, produced crack-free parts and prevented Ag leaching into the ceramic during co-firing. The green parts were sintered after SLB in a conventional furnace at 645°C for 4 h and achieved 94.5% density, compressive strength of 4097 MPa, a relative permittivity (εr) of 33.8 and a loss tangent (tan δ) of 0.0004 (8 GHz) for BMO. The feasibility of using SLB followed by a post-printing sintering step to create BMO/Ag 3D structures was thus demonstrated

Ultra- cold neutron sources: UCN production rate in solid deuterium converter

A new model is presented herein to calculate optimal value for ultra-cold neutron (UCN) production rate of a UCN source. The cold neutron (CN) converter is the main component of UCN source. In this paper, we study the UCN source which contains the D2O neutron moderator, the sD2 converter, 590 Mev proton beam, and the spallation target (a mixture of Pb, D2O and Zr). In order to determine the quantities, the neutron transport equation, written in MATLAB, has been combined with the MCNPX simulation code. The neutron transport equation in cylindrical coordinate has been solved everywhere in sD2 by using simulated CN flux as boundary value. By loading a cylindrical shell with different materials, surrounding the converter, different values for UCN production rate and density were obtained. The results of the UCN production rate and density and their comparison with previous results show that the present method has a good capability for optimization of UCN source parameters

Consideration of a ultracold neutron source in two-dimensional cylindrical geometry by taking simulated boundaries

A new idea to calculate ultracold neutron (UCN) production by using Monte Carlo simulation method to calculate the cold neutron (CN) flux and an analytical approach to calculate the UCN production from the simulated CN flux was given. A super-thermal source (UCN source) was modeled based on an arrangement of D2O and solid D2 (sD2). The D2O was investigated as the neutron moderator, and sD2 as the converter. In order to determine the required parameters, a two-dimensional (2D) neutron balance equation written in Matlab was combined with the MCNPX simulation code. The 2D neutron-transport equation in cylindrical (ρ − z) geometry was considered for 330 neutron energy groups in the sD2. The 2D balance equation for UCN and CN was solved using simulated CN flux as boundary value. The UCN source dimensions were calculated for the development of the next UCN source. In the optimal condition, the UCN flux and the UCN production rate (averaged over the sD2 volume) equal to 6.79 × 106 cm−2s−1 and 2.20 ×105 cm−3s−1, respectively

Molecular characterization of Kashk, a traditional Iranian fermented dairy product.

Kashk (Persian word meaning dry) is a popular and traditional Iranian fermented dairy product, made using buttermilk, a churning by-product of yogurt from ovine/bovine milk (Shiroodi et al., 2012). Traditional Kashk is prepared from sheep milk and sun-dried up to a considerable hardness. More recently, Kashk has started to be produced industrially with a different process, acquiring a creamy texture. Either traditional or commercial Kashk are rich sources of proteins (12-13%). Also the peptide fraction, derived from the hydrolysis of milk proteins, by action of bacterial enzymes, represents an abundant form of essential amino acids and putative active compounds