Effect of Nanosized NiF 2

We report the effect of NiF2 (10 nm) additions on the transport critical current density, Jc of (Bi1.6Pb0.4)Sr2Ca2Cu3O10/Ag sheathed superconductor tapes. Pellets of (Bi1.6Pb0.4)Sr2Ca2Cu3O10(NiF2)x (x=0–0.05 wt.%) superconductor were prepared using the acetate coprecipitation method. The sample with 0.04 wt.% addition of NiF2 exhibited the highest Jc. Ag-sheathed (Bi1.6Pb0.4)Sr2Ca2Cu3O10(NiF2)0.04 superconductor tapes were fabricated using the powder-in-tube (PIT) method and sintered at 845°C for 50 and 100 h. Jc of nonadded tapes at 30 K sintered for 50 and 100 h was 6370 and 8280 A/cm2, respectively. Jc of (Bi1.6Pb0.4)Sr2Ca2Cu3O10(NiF2)0.04/Ag tape at 30 K sintered for 50 and 100 h was 14390 and 17270 A/cm2, respectively. In magnetic fields (0 to 0.7 T), Jc of the NiF2 added tapes was also higher compared with the nonadded tape indicating that NiF2 nanoparticles can act as effective flux pinning centers and longer sintering time improved the microstructure. A steeper increase in Jc was observed below 60 K in the NiF2 added tapes which coincided with the Neel temperature, TN of nanosized NiF2 (60 K). The pronounced enhancement of Jc was attributed to the strong interaction between flux line network and the antiferromagnetic NiF2 below TN

Electrical properties and AC susceptibility of CdTe added Tl2Ba2CaCu2O8-δ superconductor

Information on semiconductor/superconductor interface is important in fabricating devices of such hybrid systems. In this paper the electrical properties and AC susceptibility of Tl2Ba2CaCu2O8 (Tl-2212) superconductor added with CdTe semiconductor are reported. Samples with nominal starting composition Tl2Ba2CaCu2O8(CdTe)x with x = 0 to 0.20 weight percent (wt. %) have been prepared by the solid-state reaction method. X-ray diffraction patterns showed essentially the Tl-2212 phase with presence of impurities (CuO and Tl2Ba2CuO6) for x ≥ 0.05 wt. % but did not change the Tl-2212 structure which is tetragonal with lattice parameter a = b ≠ c. The critical onset temperature, Tc-onset for all samples was between 104 and 108 K while the critical zero resistance temperature, Tc-zero was from 93 to 95 K. The superconducting transition determined by AC susceptibility measurement showed Tcχ’ between 101 and 103 K. The peak temperature, Tp of the imaginary part of the susceptibility χ” decreased for x = 0.05 and then increased for x > 0.05. This indicated that the superconducting grains were strongly coupled for x > 0.05 as a result of CdTe addition. The intergrain critical current density, Jc at Tp for the x = 0.2 sample Jc (Tp = 95 K) = 23 A cm-2 was the highest among all samples. This sample also showed the highest Tp indicating CdTe improved the flux pinning of the Tl-2212 phase. This result can be useful in the fabrication of semiconductor/superconductor (Tl-2212) hybrid devices

AC susceptibility and electrical properties of PbS added Bi1.6Pb0.4Sr2CaCu2O8 superconductor

The Bi1.6Pb0.4Sr2CaCu2O8 (Bi-2212) phase is an interesting superconductor. Although it’s transition temperature is lower than Bi1.6Pb0.4Sr2Ca2Cu3O10 (Bi-2223), it has a better high field performance at low temperatures. This report is regarding the effects of lead sulfide on Bi1.6Pb0.4Sr2CaCu2O8 superconductor. Samples of Bi1.6Pb0.4Sr2CaCu2O8(PbS)x for x = 0.0 to 10.0 wt.% were prepared via the solid-state-reaction route. The Bi-2212 was the majority phase in all samples with x ≤ 1.0 wt.% showing more than 95%. Scanning electron micrographs showed increase in grain size as PbS content was increased. The x = 0 sample exhibited the highest Tc-zero at 72 K and Tc-onset 83 K. The imaginary part of the AC susceptibility showed that the peak temperature, Tp increased from 59 K for x = 0 to 66 K for x = 0.6 wt.% sample. This research showed that PbS increased the flux pinning of Bi-2212 for x ≤ 1.0 wt.% although the transition temperature was suppressed

Superconductivity and elastic properties of La1.85-1.5xSr0.15+1.5xCu1-xMnxO4 with x = 0, 0.02 and 0.04

The effects of mixed-valence Mn substitution at the Cu site on the superconducting and elastic properties of La1.85-1.5xSr0.15+1.5xCu1-xMnxO4 (x = 0, 0.02 and 0.04) were studied. The samples were characterized by X-ray diffraction (XRD) method, temperature-dependent resistance measurements, scanning electron microscopy (SEM) and sound velocity measurements at room temperature. An elastic softening and a decrease in the critical temperature Tc was observed as Mn was substituted for Cu. The Debye temperature θD for x = 0 and 0.02 void free samples were calculated to be 459 K and 430 K, respectively. Internal lattice strain which is related to lattice parameter ratio a/c did not correlate with Tc. The electron-phonon coupling estimated using the conventional Bardeen-Cooper-Schrieffer (BCS) theory was λ = 0.367 (x = 0) and 0.368 (x = 0.02). The electron-phonon coupling in two-dimensional van Hove scenario was calculated to be λvH = 0.0148 (x = 0) and 0.0149 (x = 0.02). These results were compared with other cuprates and related superconductors. The comparison showed that other than electron-phonon coupling, the elastic moduli might play an important role in the mechanism of superconductivity in these materials

Error Level Analysis Technique for Identifying JPEG Block Unique Signature for Digital Forensic Analysis

The popularity of unique image compression features of image files opens an interesting research analysis process, given that several digital forensics cases are related to diverse file types. Of interest has been fragmented file carving and recovery which forms a major aspect of digital forensics research on JPEG files. Whilst there exist several challenges, this paper focuses on the challenge of determining the co-existence of JPEG fragments within various file fragment types. Existing works have exhibited a high false-positive rate, therefore rendering the need for manual validation. This study develops a technique that can identify the unique signature of JPEG 8 × 8 blocks using the Error Level Analysis technique, implemented in MATLAB. The experimental result that was conducted with 21 images of JFIF format with 1008 blocks shows the efficacy of the proposed technique. Specifically, the initial results from the experiment show that JPEG 8 × 8 blocks have unique characteristics which can be leveraged for digital forensics. An investigator could, therefore, search for the unique characteristics to identify a JPEG fragment during a digital investigation process

Alveolar rhabdomyosarcoma of the neck in a two-months-old baby: diagnostic challenges

Rhabdomyosarcoma (RMS) is the most common soft tissue malignancy in children and adolescents. The rarity of its occurrence in infant poses a great difficulty in terms of diagnosis and management. Here, we report an aggressive case of alveolar rhabdomyosarcoma in an infant who presented with neck swelling and neurological complications. The Magnetic Resonance Imaging (MRI) revealed a soft tissue swelling of the neck with intraspinal extension and spinal cord compression, raising the possibility of a neurogenic or malignant nerve sheath tumour. Histopathological examination revealed a primitive, small round cell tumour with no rhabdoid differentiation. The clinical presentation, neurological symptoms, tumor location and the histopathologic features were highly suggestive of neuroblastoma. However, the tumour cells were positive for desmin with focal and weak nuclear positivity for myogenin and MyoD1; immunoexpressions which were in favour of rhabdomyosarcoma. Fluorescent in situ hybridization (FISH) confirmed the presence of a translocation t(2;13)(q35;q14), supporting the diagnosis of alveolar rhabdomyosarcoma. Despite chemotherapy, patient succumbed to death after two months due to septic shock. Rhabdomyosarcoma is highly aggressive mesenchymal neoplasm which may present with diagnostic difficulty. This case highlights the importance of molecular studies in making an accurate diagnosis so that appropriate chemotherapy may be instituted

Sifat elektrik dan kerentanan arus ulang alik superkonduktor Bi(Pb)-Sr-Ca-Cu-O dengan penambahan In2O3

Kesan penambahan In2O3 terhadap superkonduktor (Bi1.6Pb0.4)Sr2Ca2Cu3O10 (In2O3)x (x = 0- 0.1 peratus berat) telah dikaji. Pencirian yang dijalankan ialah pembelauan sinar-X, mikrostrukur, rintangan elektrik, kerentanan arus ulang alik dan ketumpatan arus genting antara butiran. Suhu genting mula, Tc mula dan suhu genting sifar, Tc sifar adalah tertinggi bagi sampel x = 0 iaitu Tc mula = 112 K dan Tc sifar = 90 K. Corak pembelauan sinar-X menunjukkan peratus isi padu fasa (Bi1.6Pb0.4)Sr2Ca2Cu3O10 (Bi-2223) dan (Bi1.6Pb0.4)Sr2CaCu2O8 (Bi-2212) adalah hampir sama untuk semua sampel. Pengukuran kerentanan ulang alik telah dijalankan pada frekuensi 295 Hz dan medan magnet H = 5 Oe. Dua peralihan pada kerentanan ulang alik bagi x = 0 menandakan kewujudan fasa Bi-2223 dan Bi-2212. Suhu pada puncak kehilangan tenaga, Tp untuk kerentanan khayal, χ” adalah tertinggi (74 K dan 104 K) untuk x = 0. Penambahan In2O3 telah menyebabkan Tp beranjak kepada suhu lebih rendah dan ini menunjukkan fluks magnet menembusi antara butiran pada suhu yang semakin menurun apabila In2O3 ditambah. Lengkung puncak Tp juga melebar apabila In2O3 ditambah. Ini menunjukkan gandingan antara butiran yang semakin lemah dan tenaga pengepinan fluks yang menurun. Ketumpatan arus genting antara butiran Jc(Tp) telah diukur menggunakan model Bean dan nilainya adalah antara 16 hingga 20 A cm-2 bagi semua sampel. Satu model skematik arus aruhan bagi bahan polihablur yang mengandungi dua fasa superkonduktor dengan pecahan isi padu yang sama tetapi suhu genting yang berlainan dibincangkan

Synthesis And Characterization of Polymeric V2O5/AIO(OH) With Nanopores On Alumina Support

Polymeric vanadium pentixide gel was formed via the reaction of V2O5 powder with hydrogen peroxide. The polymeric vanadium pentoxide gel was then dispersed in alumina gel. Different vanadium loading composites were coated on alumina support and calcined at 500C for 1 hr. These composite layers were characterized using EDX, FT-IR, XRD, SEM, TGA and Autosorb. It was found that the lamellar structure of polymerized vanadium pentoxide was retained in the inorganic matrix. Crystalline alumina in gamma phase was formed after calcinations. However, crystalline V2O5 was not found in the composite layer and it was possibly due to low calcination temperature. Alumina top layer with 21.81 wt% of V2O5 gel showed smaller pore diameter (5.483.nm) and improved BET surface area (380.4m2/g)