Insight into Structural,Electronic, Magnetic,Mechanical, and Thermodynamic Properties of Actinide Perovskite BaPuO<Subscript>3</Subscript>

In this paper, we have performed a systematic investigation on structural, magnetic, electronic, mechanical, and thermodynamic properties of BaPuO₃ perovskite within density functional theory (DFT) using generalized gradient approximations (GGA), onsite coulomb repulsion (GGA + U), and modified Becke-Johnson (mBJ). The calculated structural parameters were found in good agreement with the experimental results. A large value of magnetic moment equal to integer value of 4 μ_B was obtained for the compound. The spin-polarized electronic band structure and density of states present 100% of spin polarization at Fermi level, resulting in half-metallic nature for the compound with spin-up states as metallic and spin- down states as a semiconducting. The elastic and mechanical properties have also been predicted. Moreover, we have calculated thermodynamic properties like Debye temperature (??_D), specific heat (C_V), entropy (S), etc. using quasi-harmonic Debye model.     

Performance validation tests on 80 K bubble type of shields for SST-1

The 80 K thermal shields of Steady State Superconducting Tokamak (SST-1) minimize the steady state heat loads on the superconducting magnet system at 4.5 K from ambient. Uniform temperature, vacuum and cryo compatibility is desired for the 80 K shields. In order to meet these requirements, the bubble/embossed type of design concept is adopted. This design ensures lower pressure drop and better temperature uniformity within ±5 K. Special attention has been given for preventing direct radiation on the magnet system. As part of performance validation tests, a group of 80 K thermal shields have undergone rigorous testing protocols and procedures. The temperature distribution, helium leak tightness and insulation resistance tests have been carried out for SST-1 thermal shields before final assembly of the machine. The test design, procedures and results of the 80 K thermal shields will be discussed in this paper.     

Significance of 8-oxoG in the spectrum of DNA damages caused by ionising radiation of different quality

The yields and composition of DNA damages caused by ionising radiation depends on radiation quality. With increasing light energy transfer (LET), the proportion of isolated DNA damages with respect to cluster damaged sites decreases. Non-double strand break complex damages are induced by gamma radiation in mammalian cells at least four times more frequently that prompt DSB. The most important product of oxidative damage to DNA bases is 8-oxo-7,8-dihydroguanine (8-oxoG). The modelling of DNA damage induced by ionising radiation of different qualities was performed to assess frequencies and composition of complex damages containing 8-oxoG. The occurrence of clusters containing 8-oxoG increases from 6 to 11% for LET in the range 0.4-160 keV microm(-1). Distributions of single strand break (SSB) on opposite DNA strand around induced 8-oxoG have similar shape for different ionising radiations, but differ in their occurrence in the whole spectrum of DNA damages. The most probable configuration is a strand break localised at position +/-3 bases from 8-oxoG.     

An integrated approach for machine tool selection using fuzzy analytical hierarchy process and grey relational analysis

Selecting a proper machine tool is one of the important decisions a company has to make. Companies which fail to do so face many problems which negatively affect the firm's productivity, flexibility, precision and its responsiveness capabilities. Selection of a machine tool involves a lot of criteria to be simultaneously studied and so it requires a multi-criterion decision making (MCDM) method to solve it. Also the subjectivity involved in such decisions ask for the use of theories such as fuzzy and grey which are very effective in handling subjective inputs. This paper integrates the fuzzy analytic hierarchy process (AHP) and grey relational analysis approaches for the selection of a machine tool from a given set of alternatives. Fuzzy AHP is used to calculate the priority weights of the criteria. Subsequently grey relational analysis (GRA) is employed to rank the alternatives. A well known problem existing in literature has been picked up for the numerical illustration. The results obtained in this paper are better when compared with that existing in literature.     

Properties of force networks in jammed granular media

Discrete element method simulations are conducted to investigate the effects of applied uniaxial compressive load, and bidisperse particle size distributions on force networks within jammed granular media. The differences between the strong and weak networks are examined through investigating the spatial correlation and distribution of contact angles, and emergence of chainlike structures. The simulation results show that the chainlike structures are more prevalent in the strong network due to the larger cumulative probabilities of contact angles, but not all the contacts belonging to the strong or weak networks are able to constitute the chainlike structures. Although the contacts of coarse-fine particles are dominant for the bidisperse systems, the contacts of coarse–coarse particles dominate the strong network, as well as the linear chainlike structures. Upon increasing the pressure from very low to high, the probability of contact orientations with respect to the compression direction in the strong network increases for contact orientation less than \(60^{\circ }\) and decreases for contact orientation greater than \(60^{\circ }\), while the opposite trends are observed in the weak network. The tails of normalized normal contact forces distributions are quantified by \(\hbox {P}(\hbox {f}) = \hbox {exp}(-\hbox {cf}^{\mathrm{n}})\), and it is found that the value of n depends on the applied pressure and particle size distribution. Statistical analysis shows that the degree of homogeneity of contact force increases with increasing pressure, which is also validated by participation number.     

Ultra-fine dispersible powders coated with l-Leucine via two-step co-milling

Dispersion of ultrafine powders is difficult due to their high cohesion and consequent agglomeration. Dry coating with additives such as nano-silica, magnesium stearate (MgSt), or Leucine (Leu), an amino acid, may help mitigate this problem. Unfortunately, when the powders to be coated are very fine, the additives such as MgSt or Leu need to be of even finer size, requiring a separate milling process. Here, a two-step co-milling process is investigated to produce well dispersible inhalable size range (<5 µm) particles. The main advantage is that the powder to be coated and additives have starting size of several hundred microns and do not require separate pre-milling. In the first step, Potassium Chloride (KCl), used as a surrogate API, and Leu are pre-milled in a ball mill to achieve KCl coated with Leu of ～10?µm. In the second step, simultaneous co-milling via jet-milling of pre-coated KCl down to inhalable size KCl, coated with Leu is done. The dispersibility of coated KCl was assessed through laser diffraction of dry powder at low dispersion pressure (Sympatec Rodos-Helos), corroborated via scanning electron microscopy (SEM), and FT4 powder tester measuring flow function coefficient (FFC), conditioned bulk density, and aerated energy. This assessment revealed that about 2?wt% Leu was adequate to provide best overall dispersibility. The dispersibility of milled KCl after coating with Leu was found to be better compared with uncoated and MgSt or nano-silica coated KCl. Overall, this two-step co-milling of KCl with 2?wt% Leu yielded well-dispersible, <5?µm particles from starting particles of two orders of magnitude larger sizes.     

Fast release of liquid antisolvent precipitated fenofibrate at high drug loading from biocompatible thin films

Motivated by recent papers on nano and micro-particle slurry casting of poorly water-soluble drugs forming biocompatible films with enhanced properties, this work explores incorporation of liquid antisolvent (LAS) precipitated suspensions of fenofibrate, a model poorly soluble drug using both semi-synthetic (HPMC E15 LV) and natural (sodium alginate, SA) polymer as film formers. Centrifugation and subsequent resuspension were employed to minimize residual solvent and increase drug loading (～20%) in the LAS suspensions and in the film. Film’s critical quality attributes (CQAs), including drug distribution and uniformity, mechanical properties, and dissolution were assessed. Crystalline nature of FNB was largely preserved in the film without any polymorphic changes confirmed by XRD, DSC, and Raman. The NIR chemical imaging, corroborated by SEM imaging and drug content relative standard deviation (RSD) indicates that the drug is uniformly distributed without any observable large agglomerates. The films with SA showed lower mechanical strength as compared to HPMC due to SA’s low molecular weight. All films exhibited immediate drug release as has been the case using FNB nano particles in previous papers. Interestingly, although addition of plasticizer improved film dissolution, HPMC-based films had a faster dissolution compared to SA-based films in spite of higher mechanical strength of the former.     

A First-Principles Calculation on Structural,Electronic, Magnetic,Mechanical, and Thermodynamic Properties of SrAmO<Subscript>3</Subscript>

For the first time, the americium-based perovskite SrAmO₃ has been studied with respect to its structural, electronic, magnetic, mechanical, and thermodynamic properties. The study has been carried within the well-known density functional theory (DFT) using different approximations such as local spin density approximation (LSDA), generalized gradient approximation (GGA), LSDA + U, GGA + U. In order to check for the stable ground state, optimization was performed for non-magnetic, ferromagnetic, and anti-ferromagnetic phases, and the compound was found to be stable in the ferromagnetic phase. The spin magnetic moment was obtained with different exchange correlations and was found to be an integer which is one of the consequences of half-metallic nature. The half-metallic nature of SrAmO₃ was also confirmed from spin-polarised band structure calculations using GGA, GGA + U, and mBJ, showing metallic nature in spin-up states and semi-conducting in spin-down states. The elastic constants, Young modulus, shear modulus, Poisson ratio, and anisotropic factor were also calculated. SrAmO₃ was found to establish ductile and anisotropic nature. Debye temperature was predicted to be 353 K from elastic constants. The thermodynamic properties, like variation of specific heat capacity, thermal expansion, and entropy, were studied in the temperature range of 0 to 600 K.