Structural,magnetic and magneto-optical studies of Mn/Al bilayer thin films on GaAs substrates

Ferromagnetism and magnetic anisotropy in Mn–Al thin films can be of great interest due to their applications in spintronic components and as rare-earth free magnets. Temperature-dependent uniaxial anisotropy has been observed in ferromagnetic MnAl thin films, which is attributed to the modification of the tetragonal lattice distortion with the change in annealing temperature, confirmed by VSM, MOKE and XRD results; the annealing time did not affect the magnetic anisotropy. A simple evaporation technique was used to deposit the Mn/Al bilayer thin films (thickness ∼ 64 nm) on GaAs substrates. A comprehensive study of the effect of annealing temperature as well as annealing time on structural, microstructural, magnetic and magneto-optical properties are reported in this paper. The ferromagnetic phase was enriched in annealed samples, which was confirmed by XRD, MOKE and magnetic hysteresis loops. XRD results revealed that the ferromagnetic τ-phase was enhanced in annealed films with the increase in annealing temperature ≥ 400 °C. Surface roughness was estimated from the AFM micrographs and was found to be increased, whereas the mean grain size was decreased on annealing the as-deposited Mn/Al bilayer thin film. The gradual increase in magnetic coercivity was found on increasing the annealing temperature. It is interesting to note that the magnetic easy axis can be tuned by changing the annealing temperature of MnAl thin films, and the easy axis changes from perpendicular to parallel direction of the film plane when the annealing temperature varies from 400 °C to 500 °C. MOKE results were also found to be consistent with the magnetic results.

Ferromagnetism and magnetic anisotropy in Mn–Al thin films can be of great interest due to their applications in spintronic components and as rare-earth free magnets.     

Deciphering molecular heterogeneity of Indian families with hereditary spherocytosis using targeted next-generation sequencing: First South Asian study

Defects in various erythrocyte membrane proteins genes (ankyrin, band-3, β- and α-spectrin and protein 4·2) can cause hereditary spherocytosis (HS). This molecular heterogeneity of HS, together with co-inherited genetic modifiers, results in marked phenotypic variability among patients. We studied the molecular spectrum and genotype-phenotype correlations in 73 families (with 113 patients) with HS. Deleterious variants including nonsense (42%), deletions (18%), splice site (20%), missense (10%) and duplication/insertion (10%) were found in 47 patients. The variants detected included sporadic and dominantly-inherited defects in ANK1 (53·2%), SPTB (36·2%) and SLC4A1 (4·2%). Compound heterozygous variants in SPTA1 (6·4%) showed autosomal recessive inheritance. Alpha-spectrin variants were associated with severe anaemia and splenectomy alleviated symptoms. Co-inherited glucose-6-phosphate dehydrogenase (G6PD) deficiency was found in 15%. G6PD variants (n = 5) led to greater transfusion requirements (1-8 times) in males with HS. Homozygosity (41%) for the promoter variant of UGT1A1 (Gilbert syndrome) led to a significantly higher mean bilirubin level (126·54 µmol/l) with a higher frequency of cholelithiasis (30%) (P < 0·001). This first-ever south Asian study on the molecular spectrum of HS found ANK1 and SPTB genes variants to be the commonest with inheritance being sporadic/dominant. Next-generation sequencing provided a relatively sensitive and rapid tool for molecular diagnosis with a diagnostic yield of 64·4%.     

Diagnostic efficacy of CT-guided transthoracic needle biopsy and fine needle aspiration in cases of pulmonary infectious disease

Purpose

The purpose of our study was to evaluate the efficacy of computed-tomography (CT)-guided transthoracic needle biopsy (TNB) and fine needle aspiration (FNA) in diagnosing pulmonary infectious diseases.

Patients and methods

We retrospectively reviewed the medical records of patients treated at our institution between October 2006 and September 2009 and identified 161 patients who had undergone CT-guided TNB or FNA. We conducted CT-guided TNB or FNA for the patients if bronchoscopy failed to provide proper diagnosis or if their thoracic lesions were not appropriate targets for bronchoscopy.

Results

Twenty-three patients were diagnosed with pulmonary infectious diseases, of whom 17 were diagnosed by CT-guided TNB or FNA; sensitivity was therefore 73.9?% (17/23). The diagnostic rate for Aspergillus infection was especially high (75?%).

Conclusion

CT-guided TNB and FNA proved to be effective as alternative methods if bronchoscopy failed to diagnose pulmonary infectious diseases, with acceptable complication rates.     

Bone Marrow Involvement in Neuroblastoma: A Study of Hemato-morphological Features

Bone marrow involvement in neuroblastoma indicates advanced stage of disease. The recent use of autologous bone marrow “rescue”, has provided an additional important reason for accurate assessment of bone marrow status in newly diagnosed patients. In this study, we analyzed 44 cases of neuroblastoma for bone marrow infiltration status and their hematological parameters. Eighty-eight bone marrow aspirate and trephine touch imprint smears and 44 trephine biopsy sections were examined in these 44 patients. Of these, 24 cases (54.5 %) showed marrow infiltration. Leucopenia and bicytopenia were significantly (p < 0.05) associated with marrow infiltration. Both bone marrow aspirate and biopsy were positive for infiltration in 16 out of 24 positive cases. Only aspirate smears were positive in 4 and only trephine biopsy in another 4 cases. The pattern of infiltration consisted of rosette formation in 40.7 % cases on aspirate smears and 22.2 % cases in trephine biopsies. Remaining cases showed diffuse and interstitial presence of tumor cells and cases positive only on trephine biopsy, showed marked stromal reaction. Bilateral trephine biopsies combined with aspirate smears picked up all positive cases compared to when they were assessed alone.     

Spontaneous CD4+ and CD8+ T‐cell responses directed against cancer testis antigens are present in the peripheral blood of testicular cancer patients

Cancer/testis antigen (CTAg) expression is restricted to spermatogenic cells in an immune‐privileged site within the testis. However, these proteins are expressed aberrantly by malignant cells and T‐cell responses against CTAgs develop in many cancer patients. We investigated the prevalence, magnitude and phenotype of CTAg‐specific T cells in the blood of patients with testicular germ cell tumors (TGCTs). CD8⁺ and CD4⁺ T‐cell responses against MAGE‐A family antigens were present in 44% (20/45) of patients’ samples assayed by ex vivo IFN‐γ ELISPOT. The presence of MAGE‐specific CD8⁺ T cells was further determined following short‐term in vitro expansion through the use of pMHC‐I multimers containing known immunogenic peptides. Longitudinal analysis revealed that the frequency of MAGE‐specific T cells decreased by 89% following orchidectomy suggesting that persistence of tumor antigen is required to sustain CTAg‐specific T‐cell immunity. Notably, this decrease correlated with a decline in the global effector/memory T‐cell pool following treatment. Spontaneous T‐cell immunity against CTAg proteins therefore develops in many patients with testicular cancer and may play an important role in the excellent clinical outcome of patients with this tumor subtype.     

Impact of Radiofrequency Ablation on Malignant Biliary Strictures: Results of a Collaborative Registry

Digestive Diseases and Sciences - Radiofrequency ablation of malignant biliary strictures has been offered for the last 3&nbsp;years, but only limited data have been published. To assess the...