Isolation and Molecular Detection of Mycoplasma gallisepticum in Commercial Layer Chickens in Sylhet, Bangladesh

Mycoplasma gallisepticum induced poultry diseases are associated with a huge economic crisis and have a considerable impact on the poultry industry worldwide. The aim of the current study was to isolate and perform molecular detection of MG circulating pathogenic strain in the commercial layer farms in the Sylhet district of Bangladesh. The entire study was conducted from January 2018 to January 2019 at three Upazilas of Sylhet district in Bangladesh. A total of 50 dead layer chickens (indicating signs of respiratory distress before death) were collected randomly from 15 different layer farms. The tissue samples, such as air sacs, trachea, and lungs, were taken from suspected dead chickens. Both cultural and PCR-based techniques were applied to identify Mycoplasma from tissue samples. The conventional PCR technique was implemented to amplify 185 bp DNA fragments for the MG. Out of 50 samples, 36% (18/50) and 70% (35/50) of MG were identified by cultural method and PCR, respectively. Based on the results of the study, it can be concluded that PCR is an easier, more sensitive, and less time-consuming method for the early diagnosis of MG in chickens, compared to cultural isolation and hence can lower the economic burden to poultry farmers caused by this disease.

Size Effect of Fe3O4 Nanoparticles on Magnetism and Dispersion Stability of Magnetic Nanofluid

It is well known that magnetic nanofluids are widely applied in various fields ranging from heat transfer to miniature cooling, and from damping to sealing, due to the mobility and magnetism under magnetic field. Herein, the PFPE-oil based magnetic nanofluids with superior magnetization and dispersion stability were obtained via regulating reaction temperature. The structures of particles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The size effects of particles on the magnetism and coating effect of particles, and on the stability and saturation magnetization of the fluids were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM) and density instrument, respectively. The results indicate that the impurity phase FeOOH only appear in the sample prepared at 18°C and the average size of Fe3O4 nanoparticles reduces from 120 to 20 nm with raising reaction temperature. The saturation magnetization of Fe3O4 particles increases firstly and then reduces with increasing particle size, which is affected by the thickness of magnetic dead layer and impurity phase FeOOH. The Fe3O4 particles could be chemically coated by PFPE-acids, and the coated mass is a little affected by particle size. The stability of the nanofluids lowers while the saturation magnetization increases firstly and then decrease with increasing particle size. At reaction temperature of 60°C, Fe3O4 particles of 25 nm and the nanofluids with superior stability and saturation magnetization were obtained. Our results indicate that the control of nanoparticles size by regulating reaction temperature can be a useful strategy for preparing magnetic nanofluids with desirable properties for various potential applications.

Advances in dielectric performance of atomically engineered perovskite nanosheet thin films

The search for new high-performance dielectric material receives continued research interest. Several mechanisms for high permittivity have been proposed such as BaTiO3-based perovskites or CaCu3Ti4O12. Nevertheless, developing thin films with such high performance remains a highly challenging task. However, reducing the BaTiO3-based film thickness raises the leakage current and suppresses dielectric responses because of a low-permittivity interfacial ‘dead-layer’. Here, we propose a new materials design route to great permittivity behavior in atomically-thin films, where charge engineering of layered perovskites generates giant polarizability and results in 2-dimensional materials with colossal permittivity. Firstly, we present a concrete example Dion-Jacobson type KSr2 − xBixNb3O10 and its cation-exchanged form HSr2 − xBixNb3O10, which exhibit a stable colossal permittivity and a low dielectric loss. Also, Sr2(1−x)Bi2xNb3O10 (x = 0.1) nanosheets attain by chemical exfoliation method with a high dielectric permittivity of over 500, the highest among all known dielectrics in the ultrathin films (< 20 nm). As Bi-substitution of Sr2Nb3O10, the dielectric permittivity exhibits two times higher value due to higher polarizability of Bi ions and leads larger dielectric permittivity. Density functional theory calculations suggest that the substitution of high-valent Bi ions with lone pairs are responsible for the colossal permittivity. Our results provide a strategy for achieving new high-k nanodielectrics for use in nano-scaled electronics.

Effect of Particle Size on Magnetic Phase Coexistence in Nanocrystalline La0.4Bi0.3Sr0.3MnO3

Magnetic phase coexistence in the substituted perovskite compound, La0.4Bi0.3Sr0.3MnO3, is attributed to the spontaneous moment and a step-like metamagnetic transition observed in the magnetization measurements in its magnetically order state. The magnetism of samples reduced to nanometer sizes by the “top down” approach exhibits interesting changes with respect to the bulk, thus giving a handle in influencing the physical properties by reducing the particle size. The bulk sample orders ferromagnetically at TC = 295 K, whereas in nano-sized samples with particle sizes in the range of 21–30 nm, even though TC does not change, the transitions are suppressed. The nano-sized powder samples show a broad hump in the plot of magnetic susceptibility, signifying the possible disordered antiferromagnetic state. A systematic decrease in the magnitude of magnetization in nano-sized samples shows that the reduction in magnetic interaction could be attributed to the formation of a magnetic dead layer around the magnetic core.

Pt and CoB trilayer Josephson $$\pi $$ junctions with perpendicular magnetic anisotropy

We report on the electrical transport properties of Nb based Josephson junctions with Pt/Co$$_{68}$$ 68 B$$_{32}$$ 32 /Pt ferromagnetic barriers. The barriers exhibit perpendicular magnetic anisotropy, which has the main advantage for potential applications over magnetisation in-plane systems of not affecting the Fraunhofer response of the junction. In addition, we report that there is no magnetic dead layer at the Pt/Co$$_{68}$$ 68 B$$_{32}$$ 32 interfaces, allowing us to study barriers with ultra-thin Co$$_{68}$$ 68 B$$_{32}$$ 32 . In the junctions, we observe that the magnitude of the critical current oscillates with increasing thickness of the Co$$_{68}$$ 68 B$$_{32}$$ 32 strong ferromagnetic alloy layer. The oscillations are attributed to the ground state phase difference across the junctions being modified from zero to $$\pi $$ π . The multiple oscillations in the thickness range $$0.2~\leqslant ~d_\text {CoB}~\leqslant ~1.4$$ 0.2 ⩽ d CoB ⩽ 1.4 nm suggests that we have access to the first zero-$$\pi $$ π and $$\pi $$ π -zero phase transitions. Our results fuel the development of low-temperature memory devices based on ferromagnetic Josephson junctions.

Interfacial properties of [Pt/Co/Pt] trilayers probed through magnetometry

The magnetic and interface properties of [Pt/Co/Pt] were investigated. First, the magnetic properties were determined from the magnetic dead layer plots, in which the Co layer was considered as two distinct parts representing different magnetic properties. The two parts with low and high tCo ranges are close to and away from the top interface (Co/Pt), respectively. The part close to the top interface shows a smaller magnetization (M) value and nonlinear behavior. However, the other part shows a higher M value closer to the bulk value and a linear behavior. The nonlinear behavior of the M values of the low tCo range was converted to an impurity level using simple assumptions. The results showed the effect of the top Pt layer on the magnetic properties of the Co layer. The results clearly demonstrate that magnetometry could be utilized as a means to understand the interface quality of magnetic multilayer systems.

Efficiency calibration of high-purity germanium detector using Monte Carlo simulations including coincidence-summing corrections: volume source case

The gamma-ray spectrometry by the instrumentality of Ge detectors is used for the detection of low activity environmental samples of different geometry (soil samples, air filters with aerosols, milk powder, etc.). Such measurements require separate calibration of the detector. The high purity germanium (HPGe) gamma-ray spectrometer of GC2520 series was used for experiments. For the efficiency calibration, three cylindrical containers filled with different 60Co water solution levels were used, and the gamma-ray coincidence summing was modelled using MCNP6. The dimensions of the pure germanium crystal, provided by Canberra, were used for the simulations. The true coincidence summing takes place when two or more gamma quanta, which are emitted in a cascade from an excited nucleus, are detected within the resolving time of the detector. However, there is often a mismatch between the simulated and experimental efficiencies. The experimentally obtained and modelled spectra were compared: a good consistency of experimental and modelled results allows investigating the volume sources. During the simulation it was found that the factors affecting the accuracy of modelling are the thickness of the dead layer, crystal dimensions and the thickness of the Al detector cap. The analysis allows measuring the radionuclides activity concentration of samples placed in the containers with different filling heights having only standard shape calibration sources. The obtained accuracy is sufficient to fulfil criteria of 5–10% for such type of simulation to be applied for measurements of real samples in standard BURK-60 containers of various sample filling heights.

Optimization of the thermal regime of the insulating breathing apparatus on chemically bound oxygen

It is proved that the main prospects for improving the insulating means of respiratory protection are related to the chemical method of oxygen reservation. To increase the efficiency of its use, it is necessary to use the resource of the dead layer of the chemosorbent and prevent the sintering of the granules of the oxygen-containing product under the action of exothermic heat. This is achieved by faster pulsed passage of exhaled air through the frontal layers of the chemosorbent and its slow filtration through the rest of the regenerative cartridge. To evaluate the effectiveness of such a technical solution, a mathematical model of air regeneration in an insulating breathing apparatus with an uneven rate of exhalation filtration through a regenerative cartridge is constructed. The dependencies on the time and coordinate of the concentration of CO2 molecules in the air stream and the share of the use of the protective resource of the regenerative cartridge are obtained. Using numerical experiments, the optimal coordinate of the air flow filtration rate jump was determined to prevent sintering of the granules. Depending on the amount of pressure damping on exhalation and inspiration for the RHS respirator, an increase in the protective effect of the device was determined and a decrease in the power of exothermic heat sources in the frontal layers of the oxygen-containing product was calculated. The results obtained confirm the effectiveness of the considered improvements of the design, which make it possible to increase the reliability of insulating breathing apparatus on chemically bound oxygen and to increase the efficiency of using their protective resource.