Electronic and optical properties of Bi2Se3 topological insulator: a promising absorbing layer for broadband photodetector

Bismuth selenide (Bi2Se3) is a van der Waals compound which has been excellently reported as thermoelectric material. Linear dispersion near Fermi energy level is an exciting feature to consider, a promising candidate for photonic device within broadband wavelengths. For this application, detailed knowledge of its structural, electronic and optical properties is very essential. The electronic properties were determined by density functional theory (DFT) calculations implemented in Quantum-Espresso simulation package which uses plane wave basis and pseudopotential for the core electrons. Optical properties are computed by solving Bethe-Salpeter equation of many-body perturbation theory (MBPT) as implemented in Yambo code. The band structure results show the semiconducting behaviour of Bi2Se3. Taken into account the effects of electron-hole interaction by solving Bethe-Salpeter equation, the calculated optical properties are in better agreement with available experimental results. The exciton energy shows that the title material can absorb light within infrared region

Histopathological features of peripheral T-cell lymphoma in Sprague Dawley rats induced with N-methyl-N-nitrosourea

This study described the histopathological features of peripheral T-cell lymphoma in male Sprague Dawley rats following intraperitoneal (i.p.) injections of N-methyl-N-nitrosourea (MNU) at a dose of 60 mg/kg body weight per injection, administered twice weekly for 2 consecutive weeks, and followed by a five-month’s observation period. Control rats were injected with normal saline, i.p. All the rats treated with MNU had enlargement of lymph nodes, with 30% had hepatosplenomegaly and 7% had enlarged kidneys at necropsy. Malignant lymphoma was observed in the lymph nodes, spleen, liver, lung, heart, and kidneys. The neoplastic cells were characterised as undifferentiated, and small to large size with bizarre pleomorphic nuclei. The severity was further described as mild, moderate and severe, based on the diffuseness of the lesions. Nonetheless, similar lesions were not observed in the thymus of the rats. Immunohistochemistry staining of the organs was positive for CD3 antibody, which is consistent with T-cell lymphoma

Detection of Bcl-2 gene in leukaemic rats using an EvaGreen real-time RT-PCT assay

Bcl-2 is an anti-apoptotic gene that is involved in the apoptosis process. Suppression of apoptosis by anti- apoptotic gene can contribute to the occurrence of diseases such as leukaemia. The objectives of this study were 2-folds: first, to compare the sensitivity of an EvaGreen quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) with a conventional RT-PCR for the amplification of the Bcl-2 gene; second, to determine the expression of the Bcl-2 gene in N-methyl-N-nitrosourea (MNU)-induced leukaemiain rats using the EvaGreen qRT-PCR assay. A total of 32 male Sprague Dawley rats were assigned into two groups (n=16), namely, control and MNU groups. In particular, MNU was administered intraperitoneally (i.p) at a dose of 60 mg/kg body weight per injection at two times per week for 2 consecutive weeks. The rats were sacrificed after five months and blood samples were collected for RNA extraction and haemogram. The RNAs were converted into cDNA and amplified using both the EvaGreen qPCR and the conventional PCR assays. All the results were normalised with a housekeeper gene, i.e. glyceraldehyde 3-phosphate dehydrogenase (GADPH). The products of amplification were run on gel electrophoresis and all the results were then compared. Based on the relative intensity of the bands, the EvaGreen qRT-PCR assay was highly sensitive compared to the conventional RT-PCR assay as the Bcl-2 gene could not be amplified using the conventional RT-PCR. Interestingly, the results in this study showed that the expression of Bcl-2 was higher in rats with marked lymphocytosis as compared to the leukaemic rats with normal to mildly increase in lymphocyte count. In conclusion, EvaGreen qRT-PCR assay is more sensitive compared to the conventional RT-PCR, and Bcl-2 gene is abundantly expressed in leukaemic rats with marked lymphocytosis compared to the leukaemic rats with normal to mildly increase in lymphocyte number

Effect of nano-sized Co3O4 addition on the transport properties of YBa2Cu3O7−δ

The effect of nano-sized Co3O4 (10 - 30 nm) addition on YBa2Cu3O7−δ(Co3O4)x with x = 0 to 0.12 wt.% has been investigated by powder X-ray diffraction method, dc electrical resistance measurements and scanning electron microscopy. The Co3O4 particle size was larger than the coherence length but smaller than the penetration depth of the YBa2Cu3O7−δ superconductor. The onset transition temperature (T c onset) showed no significant changes for low Co3O4 addition (x ≤ 0.02 wt. %) and then decreased monotonically with the increase in Co3O4 content indicating a pair-breaking like mechanism in T c suppression for x = 0.03 to 0.12 wt. %. A sudden broadening of the superconducting-transition-width for x ≥ 0.11 wt. % was also observed. The transport properties were measured and related to the microstructure. Scanning electron micrographs showed homogeneous distribution of Co3O4 throughout the samples and the distance between particles was smaller than 1 μm but larger than the typical Abrikosov vortex lattice constant

Grain - matrix mosaic contribution to ac losses in Ni-doped BSCCO cylinders.

The measurements of ac susceptibility χ = χ′+iχ′′is performed to determine the characteristics of intergranular components in sintered Bi1.6Pb0.4Sr2(Ca1-xNix)2Cu3Oδ, (x = 0.0 – 0.05) polycrystalline cylinders prepared by the conventional route. Theoretical values of for idealized cylinder were calculated in the range " χ max ≤ k ≤10 , correspondence of the Bean and the simplified Kim critical state models. Magnetization curve for various stages in the specimens is hence approximated. It is found that Ni content in BSCCO system changes the effective volume fraction of the grains, field dependence of the intergranular critical current density, transition temperature, and the intergranular pinning property

Investigating the Association between Physical Health Comorbidities and Disability in Individuals with Severe Mental Illness

BACKGROUND: Research suggests that an increased risk of physical comorbidities might have a key role in the association between severe mental illness (SMI) and disability. We examined the association between physical multimorbidity and disability in individuals with SMI. METHODS: Data were extracted from the clinical record interactive search system at South London and Maudsley Biomedical Research Centre. Our sample (n = 13,933) consisted of individuals who had received a primary or secondary SMI diagnosis between 2007 and 2018 and had available data for Health of Nations Outcome Scale (HoNOS) as disability measure. Physical comorbidities were defined using Chapters II–XIV of the International Classification of Diagnoses (ICD-10). RESULTS: More than 60 % of the sample had complex multimorbidity. The most common organ system affected were neurological (34.7%), dermatological (15.4%), and circulatory (14.8%). All specific comorbidities (ICD-10 Chapters) were associated with higher levels of disability, HoNOS total scores. Individuals with musculoskeletal, skin/dermatological, respiratory, endocrine, neurological, hematological, or circulatory disorders were found to be associated with significant difficulties associated with more than five HoNOS domains while others had a lower number of domains affected. CONCLUSIONS: Individuals with SMI and musculoskeletal, skin/dermatological, respiratory, endocrine, neurological, hematological, or circulatory disorders are at higher risk of disability compared to those who do not have those comorbidities. Individuals with SMI and physical comorbidities are at greater risk of reporting difficulties associated with activities of daily living, hallucinations, and cognitive functioning. Therefore, these should be targeted for prevention and intervention programs

Simple preparation and characterization of bismuth ferrites nanoparticles by thermal treatment method

In the present work, nanoparticles of multiferroic bismuth ferrites (BiFeO3) were synthesized via a simple thermal treatment method. BiFeO3 was prepared from an aqueous solution containing bismuth nitrate and iron nitrate as starting materials, polyvinyl pyrrolidone (PVP) as a capping agent and nitric acid to dissolve the bismuth nitrate, respectively. It is followed by thermal treatment at various calcination temperatures at 350, 450 and 550 °C. The samples were characterized by thermogravimetric analysis, X-ray diffractometer (XRD), transmission electron microscope (TEM), vibrating sample magnetometer and electron spin resonance (ESR) spectroscopy. XRD results indicate that the samples, calcined at 350, 450 and 550 °C, crystalized in rhombohedral crystal structure (space group R3c). The crystallinity of samples increased with increasing calcination temperature. Morphology study using TEM confirmed the growth of BiFeO3 nanoparticles with the average particle’s size increases from ~30 nm up to ~80 nm with the increasing of calcination temperature from 350 to 550 °C. Magnetic saturation Ms, of samples decreased from 2.15 to 0.25 emu/g while the coercivity Hc, increased from 54.41 to 272 G when the calcination temperature increased from 350 to 550 °C. ESR revealed increment of g-factor value from 2.14 to 2.64 and peak-to-peak linewidth from 129.33 to 201.61 Oe with the increasing of calcination temperature from 350 to 550 °C. The results demonstrate that by using thermal treatment method, the BiFeO3 nanoparticles can be obtained at low temperature, i.e. 350 °C

Haematological parameters of leukaemic rats supplemented with Morinda citrifolia

Morinda citrifolia (mengkudu) had been reported to have anti-tumor activity, which has been researched widely in several animal models. Sixty four eight-week-old male Sprague Dawley rats were divided into four groups of 16 rats per group namely control, MNU, Morinda citrifolia (MC), and MC+MNU group. The MNU and MC+MNU groups received four consecutive intraperitoneal (i.p) injections of N-methyl-N-nitrosourea (MNU) at a dose of 60 mg/kg for induction of leukaemia. Rats in the MC and MC+MNU groups were fed daily with a ration mixed with M. citrifolia at a dose of 5000 mg/kg body weight. The peripheral blood samples were collected at 20 weeks post MNU administration into EDTA tubes and analysed for a complete blood count. Blood smears stained with Wright’s stain were prepared for a manual differential leukocyte count and examination of the leukaemic cells. The results were analysed using a one-way ANOVA. Results in this study showed that MNU group had significant lymphocytosis (66.9±98.14) compared to the other groups. The morphology of the lymphocytes in the MNU and MC+MNU groups showed a typical morphology of leukaemic cell, while the other groups had normal lymphocyte morphology. Rats in the MNU group also had anaemia with significant reduction in total erythrocyte number (6.11±2.73 x 1012/L), haemoglobin concentration (131.64±21.32 g/L) and packed cell volume (37.92±8.50 L/L). The erythron parameters of MC+MNU group were comparable to the control and MC groups. In conclusion, daily supplementation of M. citrifolia reduced the proliferation of circulating leukaemic cells

Investigation of enhanced double weight code in point to point access networks

© 2020 Published under licence by IOP Publishing Ltd. In this paper, an investigation and evaluation to enhanced double weight (EDW) code is performed, a new technique for code structuring and building using modified arithmetical model has been given for the code in place of employing previous technique based on Trial Inspections. Innovative design has been employed for the code into P2P networks using diverse weighted EDW code to be fitting into optical CDMA relevance applications. A new developed relation for EDW code is presented, the relation is based on studying and experimenting the effect of input transmission power with code weight, and the relation developed using numerical analysis method. This relation makes the estimation for the system input power needed more efficient. The results of the code has been explained by eye diagram and parametric illustrations from the simulated results. The result shows a magnificent performance of the code during high number of users and weight. On the other hand, the relation developed for power measurement helps to prevent power loss and consumption

Investigation the nonlinear optical properties of silver nanoparticles using femtosecond laser

© 2020 Published under licence by IOP Publishing Ltd. In this research, the fabrication of silver nanoparticles and experimental nonlinear response (NLO). The fabrication of the silver nanoparticles has been done using E-Beam evaporation on a glass substrate (Ag-NPs) and investigation of their nonlinear optical response (NLO). The silver nanoparticles was evaluated by optical spectrum (UV-Vis) that shows localized surface Plasmon band at 375 nm. The experiment shows the nonlinear absorption and nonlinear refraction effect of silver nanoparticles, the silver nanoparticles is analysed by Z-Scan technique using a femtoseconds laser with 800 nm wavelength. The result shows the nonlinear absorption (NLA) is at 4.8710-4cmW-1, while (NLR) is at 7.9410-9cmW-1