Revealing magnetic and physical properties of TbFe4.4Al7.6: experiment and theory.

We report on the magnetic, electrical transport, caloric and electronic structure properties of TbFe4.4Al7.6polycrystalline alloy using experiment and theory. The alloy crystallizes in tetragonal structure with I4/mmm space group with lattice parametersa = b= 8.7234(5) Å andc= 5.0387(6) Å. It is ferrimagnetic with a compensation temperature ofTcmp∼151 K, Curie-Weiss temperatureθCW∼172.11 K and an effective magnetic momentµeff= (2.37±0.07)µB/f.u withZ= 2. At low temperatures, kinetic arrest-like first-order phase transition is realized through the thermal hysteresis between field-cooled cooling and field-cooled warming curves ofM(T) and virgin curves ofM(H) andρ(H)which are outside the hysteresis loops with metamagnetic transition. The high magnetic field suppression of multiple transitions and reduced coercive fieldHcoerand remnant magnetizationMremwith increasing temperature are reported.HcoerandMremcease to exist above the compensation temperatureTcmp. A correlation between the isothermal magnetization and resistivity is discussed. Specific heatC(T) analysis reveals a Sommerfeld parameter ofγ= 0.098 J⋅mol-1⋅K-2and a Debye temperature ofθD∼351.2 K. The sample is metallic as inferred from theρ(T)behavior and Sommerfeld parameter. The magnetoresistance of the alloy is low and negative which indicates the suppression of weak spin-fluctuations. This alloy avoids the tricritical point despite first-to-second order phase transition. The electronic and magnetic structure calculations, by making use of full potential linearized augmented plane wave method, suggest metallic ferrimagnetic ground state of TbFe4.4Al7.6with Tb atoms contributing ferromagnetically (5.87µB) and Fe atoms with antiferromagnetic contribution (2.67µB), in close agreement with the experimental observation.

Sella Bugged! Abscess Inside a Craniopharyngioma: Case Report with Literature Review.

INTRODUCTION: Abscess within a craniopharyngioma (CPG) is extremely rare and only 8 such cases have been reported in literature. Most patients present with hypopituitarism and visual disturbances. We report the first ever case of a CPG with abscess in a pediatric patient. CASE REPORT: A 10-year-old girl presented with visual deterioration and bitemporal hemianopia. Her CT and MRI brain suggested of a sellar-suprasellar CPG. Due to ill-developed sino-nasal anatomy, a transcranial approach was made for the lesion. The lesion was well capsulated, thick walled, and appeared inflamed. Upon incising the wall, thick yellowish pus was drained out in a controlled manner. This was followed by a partial resection of the CPG wall and eccentric, adhered, calcified residue was left behind with an Ommaya drain. The abscess culture grew Enterococcus species and histopathology revealed adamantinomatous CPG. Patient underwent culture sensitive antibiotics course followed by radiation for the residue. She was doing well at 1-year follow-up with clinical and radiological improvement. CONCLUSION: This is the first report of a pediatric case with secondary abscess in CPG. Operative management of such a case includes controlled drainage of pus without dissemination into the surrounding arachnoid space. The tumor and abscess have to be addressed as separate surgical entities; infection control and wherever complete resection is not feasible, partial safe resection followed by radiotherapy is a viable option.