Post-menopausal alopecia due to ovarian hyperandrogenaemia treated with bilateral salpingo-oophorectomy

Introduction: Increased ovarian production of androgens due to the stimulation of luteinizing hormone (LH) on theca cells can cause hyperandrogenism that may present with signs of alopecia in postmenopausal women. Case description: A 65-year-old postmenopausal woman presented to the gynecology clinic with male-pattern baldness. Serum testosterone was high that was suppressed with gonadotropin-releasing hormone analog (GnRH agonist). This confirmed ovarian source of androgens. Laparoscopic salpingo-oophorectomy helped reduce androgen levels over a period of an year therefore reversing at least partially the hair loss. Conclusion: Gonadotropin-releasing hormone analogs can be useful to diagnose the source of increased androgen levels to be of ovarian origin. Once confirmed, laparoscopic bilateral salpingo-oophorectomy can reverse hair loss in these cases

Synthesis of novel piperazine-linked anthranilic acids as potential small molecule kinase inhibitors

Please cite as follows: Chakravorty, S. et al. 2014. Synthesis of novel piperazine-linked anthranilic acids as potential small molecule kinase inhibitors. South African Journal of Chemistry, 67:71–79.The original publication is available at http://www.journals.co.za/sajchemSubstituted anthranilic acid and piperazines were used as building blocks to prepare two libraries of compounds, with the aim being that they would exhibit biochemical activity as small molecule kinase inhibitors. The synthesized anthranilamidepiperazine compounds were subsequently tested against a panel of kinases including EGFR, Abl, Akt and Aurora B.http://www.scielo.org.za/scielo.php?script=sci_abstract&pid=S0379-43502014000100012&lng=en&nrm=iso&tlng=enPublisher's versio

Electrical and magnetic properties of cold compacted iron-doped zinc sulfide nanoparticles synthesized by wet chemical method

Iron-doped (1–5%) zinc sulfide nanocrystals were synthesized with sizes ranging from 2 to 4 nm. Resistivity measurements were carried out on cold compacted specimens over the temperature range 313–472 K. A resistivity decrease of about 10 orders of magnitude was observed as compared to that of ZnS samples. The data analysis showed that conduction occurred by a small polaron hopping mechanism between Fe²⁺ and Fe3+ ions concentrated at the nanocrystal interfaces. Low temperature magnetization studies indicated ferromagnetic behaviour arising out of a one-dimensional magnetic system with antiparallel spin alignment

Multiferroic GaN nanofilms grown within Na-4 mica channels

Gallium nitride nanofilms grown within nanochannels of Na-4 mica structure, exhibit ferromagnetism even at room temperature due to the presence of gallium vacancies at the surfaces of the nanofilms. These nanofilms also show a ferroelectric behavior at room temperature ascribed to a small distortion in the crystal structure of GaN due to its growth within the Na-4 mica nanochannels. A colossal increase in 338% in dielectric constant was observed for an applied magnetic field of 26 kOe. The magnetoelectric effect is ascribed to magnetostriction of magnetic GaN phase

Anomalous magnetic behaviour of Cr<SUB>2</SUB>O<SUB>3</SUB>-SiO<SUB>2</SUB> nanocomposites

Nanocomposites containing Cr<SUB>2</SUB>O<SUB>3</SUB> particles having dimensions in the range 13-35 nm dispersed in a silica matrix have been prepared by a chemical method. X-ray diffraction investigation and high resolution electron microscopy substantiate the formation of Cr<SUB>2</SUB>O<SUB>3</SUB> particles. X-ray photoelectron spectroscopy studies show the presence of a small amount of CrO<SUB>2</SUB>. The samples exhibit ferromagnetic property below 300 K with the hysteresis loop showing an exchange bias. The latter is explained as arising due to exchange interaction between the spins associated with Cr<SUP>3+</SUP> and Cr<SUP>4+</SUP> ions. Dc electrical resistivity measurements were analysed by a small polaron hopping model confirming the presence of Cr<SUP>4+</SUP> ions at the surface of the particles. At temperatures above 100 K the magnetic hysteresis loop shift was such that zero magnetization was observed only for the negative magnetic field. This was explained as being due to a disorder effect on the magnetic spins of Cr<SUP>4+</SUP> ions

Resistivity hysteresis of Ag<SUB>2</SUB>S nanocomposites

A low-temperature chemical synthesis route was used to prepare Ag<SUB>2</SUB>S particles with diameters ranging from 3 to 39 nm within a silica matrix. The dc electrical resistivity was measured in the temperature range of 320-460 K. A drastic reduction in resistivity around 450 K was caused by an order-disorder transition of Ag<SUB>2</SUB>S. The specimens exhibited a hysteresis in resistivity as a function of temperature. The width of the hysteresis was related to the particle size, viz., it increased with an increase in particle size. This is believed to arise due to a reduction in interfacial free energy for crystal formation in the cation sublattice for smaller Ag<SUB>2</SUB>S particle sizes

Surface optical Raman modes in GaN nanoribbons

Raman scattering studies were performed in GaN nanoribbons grown along [1 0 0]. These samples were prepared inside Na-4 mica nanochannels by the ion-exchange technique and subsequent annealing in NH₃ ambient. Detailed morphological and structural studies including the crystalline orientation were performed by analyzing the vibrational properties in these GaN nanoribbons. Pressure in the embedded structure was calculated from the blue shift of the E₂(high) phonon mode of GaN. Possible red shift of optical phonon modes due to the quantum confinement is also discussed. In addition to the optical phonons allowed by symmetry, two additional Raman peaks were also observed at ∼633 and 678 cm⁻¹ for these nanoribbons. Calculations for the wavenumbers of the surface optical (SO) phonon modes in GaN in Na-4 mica yielded values close to those of the new Raman modes. The SO phonon modes were calculated in the slab (applicable to belt-like nanoribbon) mode, as the wavenumber and intensity of these modes depend on the size and the shape of the nanostructures. The effect of surface-modulation-assisted electron–SO phonon scattering is suggested to be responsible for the pronounced appearance of SO phonon modes. A scaling factor is also estimated for the interacting surface potential influencing the observed SO Raman scattering intensities

Dendron-like growth of silver nanoparticles using a water-soluble oligopeptide

A dendron-like nanostructure of silver was grown in solution using a water-soluble tetrapeptide Tyr-Aib-Tyr-Val (Aib, α-amino isobutyric acid), silver nitrate, and methanol. These structures are composed of silver nanoparticles having a bimodal size distribution with the median diameters around 2.0 and 19.5 nm, respectively. The dendron-like growth is ascribed to the effect of the local electric field generated by the dipoles associated with the peptide molecules. The optical absorption spectra have been analyzed by Mie scattering theory, which shows that there is a metal-nonmetal transition in silver particles having diameters less than ~2.0 nm

Multiferroic behavior in silicate glass nanocomposite having a core-shell microstructure

Nanosized iron core and barium titanate shell microstructure was generated within a silicate glass of composition 23.1 Na<SUB>2</SUB>O, 23.1 BaO, 23.0 TiO<SUB>2</SUB>, 7.6 B<SUB>2</SUB>O<SUB>3</SUB>, 5.8 Fe<SUB>2</SUB>O<SUB>3</SUB>, 17.4 SiO<SUB>2</SUB> by first reducing it at 893 K for 1/2 h and then subjecting it to heat treatment at 759 K for 4 h. Transmission electron microscopy showed the composite particles to have a mean diameter of 3.9 nm. The nanocomposite exhibited both ferroelectric and ferromagnetic behavior. The dielectric constant peak was not prominent because of a small thickness of the barium titanate phase. The magnetic hysteresis loop showed an asymmetric behavior giving rise to a small exchange bias field. This is believed to arise due to exchange interaction between the ferromagnetic iron core and the thin layer of Fe<SUB>3</SUB>O<SUB>4</SUB> on the core surface with a spin glass-like behavior. The magnetization under zero-field cooled (ZFC) and field cooled (FC) conditions indicated superparamagnetic behavior at temperatures higher than 300 K. The optical absorption spectra exhibited a peak at around 325 nm. This was analyzed satisfactorily on the basis of a metal core-oxide shell nanoconfiguration. The extracted values of metal core conductivity showed a metal insulator transition for iron core diameters less than 2.4 nm. The present synthesis approach will lead to newer multiferroic nanocomposites and glasses with multifunctionalities

Multiferroic behavior in composites of nickel-exchanged glass containing nanoparticles of barium titanate

A multiferroic material has been synthesized by first growing BaTiO<SUB>3</SUB> nanocrystals in a silica glass and then subjecting the composite to a two-stage ion-exchange reaction of the type Ti<SUP>4+</SUP> &lt; &gt; 2Ni<SUP>2+</SUP>. The nanocomposite retained the usual ferroelectric characteristics with lower values of the dielectric constant and remanent polarization. It also showed ferromagnetic hysteresis at temperatures in the range 10-300 K. At temperatures below ~10 K, the magnetization exhibited a sharp increase as the temperature was reduced. This has been explained on the basis of a one-dimensional Heisenberg ferromagnet consisting of Ni<SUP>2+</SUP> ions at the surfaces of the nanocrystals. The nanocomposite showed magnetodielectric coupling at room temperature. The dielectric constant increased as a function of magnetic field, showing a maximum at 4 kOe. This has been ascribed to magnetostriction of the new BaTiO<SUB>3</SUB>nanocrystalline phase