Solvent Uptake of Liquid Rubber Toughened Epoxy/Clay Nanocomposites

Carboxyl-terminated poly (butadiene-co-acrylonitrile) (CTBN) liquid rubber toughened epoxy (epoxy/CTBN blend) and CTBN-toughened epoxy/clay nanocomposites (epoxy/clay/CTBN nanocomposites) were prepared, and solvent (acetone) uptake was studied as a function of CTBN content. It was found that in both epoxy/CTBN blend and epoxy/clay/CTBN nanocomposites, the diffusion coefficient initially increased with an increase in CTBN content, with a maximum value registered for the systems containing 15 phr of CTBN. With a further increase of CTBN, the diffusion coefficient was found to decrease. The variation of solvent uptake with CTBN content depends on both the amount of dissolved rubber in the epoxy phase and the phase morphology associated with each composition. The high acetone uptake in 15 and 20 phr CTBN-loaded system was found to be reduced dramatically by the incorporation of 3 phr nanoclay. Owing to the presence of high aspect ratio clay platelets, the diffusion of acetone undergoes a more tortuous path in epoxy/clay/CTBN nanocomposites than in epoxy/CTBN blends. A diffusion mechanism correlated to composition for epoxy/CTBN blend and epoxy/clay/CTBN nanocomposites was proposed.Scopu

Cervical extradural metastasis from follicular carcinoma thyroid after 14 years post-thyroidectomy with Elsberg phenomenon

Background. Follicular carcinoma thyroid usually metastasises to bone. Common sites of bone metastasis include skull and spine. Spinal metastasis are more common in the cervical region followed by dorsolumbar spine. Cervical extradural lesions present with progressive quadriparesis, sensory loss, dysautonomia, and respiratory distress. Typical Elsberg phenomenon in a cervical extradural lesion is rare. Elsberg phenomenon involves the involvement of ipsilateral upper limb, ipsilateral lower limb followed by contralateral lower limb and contralateral upper limb. Case presentation. We are reporting a case of 47-year-old lady presented with progressive quadriparesis of 1-month duration. Her weakness started in left upper limb followed by left lower limb, right lower limb and right upper limb weakness. She also had sensory loss below the level of C7. She had undergone near-total thyroidectomy for solitary thyroid nodule 14 years back and was on thyroid supplementation since then. Histopathology at that time was reported as follicular adenoma with Hashimoto thyroiditis. Her right upper limb power was grade 4- Left upper limb grade 1 right lower limb Grade 3, left lower limb grade 2 with hypertonia of both upper and lower limbs. She was evaluated with MRI Spine which showed a dumb bell-shaped extramedullary lesion involving the C5-C6 vertebra with significant cord compression and encasement of the left vertebral artery. USG neck showed left supraclavicular lymph node enlargement and small residual thyroid tissue in the left side of the thyroid. USG guided FNAC from the thyroid tissue and neck nodes were inconclusive. The patient underwent C4 and C5 laminectomy and subtotal excision from the cervical lesion. Histopathology was reported as metastasis from follicular carcinoma thyroid. Postoperatively patient limb power improved to grade 3 left upper and lower limbs and was discharged and later referred for radioiodine ablation Conclusion. Cervical extradural metastasis from follicular carcinoma thyroid can present with Elsberg syndrome even without any neck swelling even after decades of post thyroidectomy status for a benign aetiology. Laminectomy and decompression may lead to clinical improvement

Ultrathin nanoplatelets of six-line ferrihydrite enhances the magnetic properties of hexaferrite

High-performance bulk hexaferrite permanent magnets have been fabricated through dry-processing of ferrites without applying a magnetic field in the alignment process. This novel method takes advantage of the anisotropically platelet shaped antiferromagnetic six-line ferrihydrite in the presence of Sr$^{2+}$ ions. The precursor has been prepared using a simple hydrothermal synthesis and the nanocrystallites have been subjected to subsequent compaction by Spark Plasma Sintering (SPS). The synthesis produced ∼7 nm thick six-line ferrihydrite platelets. A low SPS temperature of ∼750 °C was sufficient to obtain highly aligned strontium hexaferrites (SrFe$_{12}$O$_{19}$) with the magnetic easy axis parallel to the pressing direction. The best performing magnet produced a square hysteresis loop, with a high (BH)$_{max}$ of 33 kJ m$^{−3}$. In short, the alignment of the crystallites was controlled merely by the anisotropic crystallite shape obtained from the hydrothermal synthesis, rather than an applied external magnetic field. Three different hydrothermal synthesis temperatures were employed 100, 150, and 200 °C to synthesize thin six-line ferrihydrite nanoplatelets. Powder diffraction Rietveld modelling revealed the precursor to contain goethite ($α$-FeOOH) in addition to the six-line ferrihydrite, at higher hydrothermal processing temperatures. Rietveld refinements, texture investigations, and measured magnetic properties of the SPS pellets revealed an increase in alignment along the c-axis with an increase in hydrothermal processing temperature T$_{Hyd}$. A new method is demonstrated for making highly aligned SrFe$_{12}$O$_{19}$ permanent magnets based on the conversion of antiferromagnetic six-line ferrihydrite platelets

Exploiting different morphologies of non-ferromagnetic interacting precursor’s for preparation of hexaferrite magnets

Sintered cold compacted hexaferrite magnets with appreciable magnetic properties and crystallite alignment were made from non-magnetic precursors without applying an external magnetic field. This work presents a novel approach employing non-ferromagnetic interacting precursors comprising of platelet shaped six-line ferrihydrite and needle shaped goethite nanoparticles. A hydrothermal synthesis route was employed to produce platelet shaped six-line ferrihydrite of ~5 nm thickness. Needle shaped goethite nanoparticles were likewise prepared by hydrothermal synthesis with apparent dimensions of ~10 × 27 × 10 nm$^3$ extracted from X-ray powder diffraction data. The powder diffraction Rietveld modelling also revealed the presence of an amorphous phase in the six-line ferrihydrite and a SrCO$_3$ impurity. The presence of needle shaped goethite nanoparticles improves the alignment of magnets, while retaining the coercivity (H$_c$), in contrast to hexaferrite magnets prepared from six-line ferrihydrite by spark plasma sintering (SPS). The non-ferromagnetically interacting precursors were directly converted to the SrFe$_{12}$O$_{19}$ magnets by pressing them with conventional compaction technique followed by subsequent sintering of the pellets. Decoupling the pressing and sintering step is interesting for industrial production of magnets. The hexaferrite magnets prepared displayed good combination of saturation magnetization M$_s$ = 70 Am$^2$/kg and coercivity H$_c$ = 297 kA/m with some degree of alignment of the crystallites M$_r$/M$_s$ = 0.71. This procedure exploits the anisotropic shape of the crystallites and compaction using uniaxial pressure followed by sintering into aligned bulk magnets. Two sets of hexaferrite bulk magnets were prepared by sintering at 900 °C and held for 2 h and 1050 °C with a holding time 0 min. The hexaferrite magnets sintered at 1050 °C were subjected to transmission pole figure analysis. The texture index for each pellet were extracted from the pole figure analysis. Employing needle shaped goethite nanoparticles actually enhanced the alignment of the hexaferrite magnets. The magnet obtained from only six-line ferrihydrite displayed only a slightly improved texture index when compared with mixture of six-line ferrihydrite and goethite nanoparticles

Alignment of strontium hexaferrite, by cold compaction of anisotropic non-magnetically interacting crystallites

Cold compacted, anisotropic shaped non-magnetically interacting precursors are used to achieve aligned strontium hexaferrites. The simple process of dry mixing platy hematite and/or rod-like goethite with strontium carbonate removes the need for external magnetic fields or high temperatures during compaction to assist in alignment. The calcined strontium hexaferrite pellets all displayed preferred orientation and high levels of phase purity (>99 wt%). The mix of goethite and strontium carbonate achieved the highest degree of magnetic alignment with Mr/Ms reaching 0.83(1) obtained by vibrating sample magnetometry. The magnetic data were supported by examining crystallographic alignment using powder X-ray diffraction as well as 2D texture synchrotron analysis

Early and late presentations of ethylene glycol poisoning.

Comment in Am J Kidney Dis. 2009 Oct;54(4):780

High-Performance Hexaferrite Ceramic Magnets Made from Nanoplatelets of Ferrihydrite by High-Temperature Calcination for Permanent Magnet Applications

Highly aligned ceramic hexaferrite magnets with high-energy products $(BH)_{max}$ and a density exceeding 90% of theoretical density have been fabricated. The precursors were an antiferromagnetic powder, a six-line ferrihydrite mixed with SrCO$_3$, and a grain growth inhibitor SiO$_2$. Conventional cold compaction of the precursor powders was employed prior to calcination at temperatures of 1050, 1150, and 1250 °C. The influence of calcination temperature and magnetic properties has been systematically studied in the produced ceramic magnets. Conventional cold compaction is a favorable route for industrial production when compared with other compaction techniques like spark plasma sintering, hot compaction, or electroforging. A high $(BH)_{max}$ of 25.2 kJ/m$^3$ was obtained for the best magnet along with an appreciable coercivity, Hc, of 187 kA m$^{–1}$, a high squareness ratio, $M_r/M_s$, of 0.84, and a saturation magnetization, $M_s$, of 73 A m$^2$/kg. Texture and crystallite size analysis were extracted from 2D synchrotron transmission powder diffraction measurements. We have demonstrated that high-performance bulk magnets for permanent magnet applications can be produced from nonmagnetic interacting crystallites mixed with a grain growth inhibitor without applying a magnetic field for alignment