Observation of quantum confinement effect on ZnO embedded mesoporous silica

Nonionic surfactant as liquid organic template and tetraethoxysilane as silica precursor were used for the synthesis of mesoporous silica with ordered arrangement of nanopores (diameters are about 1-6 nm). The synthesized mesoporous silica was used as the template for the synthesis of ZnO nanoparticles using zinc acetylacetonate as ZnO precursor. The as synthesized ZnO incorporated in the mesoporous silica nanocomposite were analyzed using X-ray diffraction, TEM and Photoluminescent spectrum. ZnO introduction has no extensive influence on the mesoporous structure of silica. Quantum confinement effects are observed in the case of ZnO nanoparticles embedded in mesoporous silica. The particle size of ZnO is about 3.2 nm. The band gap is broadening to 3.47 eV.

Dia-magnetic to ferro-magnetic behavioral change of Fe-catalysts based nitrogenated carbon nanotubes (NCNTs) by the process of chlorination/oxidation

In this work, we have synthesized multiwall nitrogenated carbon nanotubes (MW-NCNTs) with Fe-catalysts by the microwave plasma-enhanced chemical vapor deposition process @950 degrees C and subsequently functionalized with chlorine and oxygen. The dia-magnetic behavioral M-H loop of non-functionalized MW-NCNTs were turn into ferromagnetic behaviors by the process of chlorination and oxidation respectively; which were characterized by means of superconducting quantum interference device magnetometer within the temperature range 5-300 K. A prominent cusp like behavior is also observed at around approximately 45 K in M(FC) and M(ZFC) measurements confirming the ferromagnetic behaviors of these MW-NCNTs after chlorination and oxidation.

Magnetic characterization of radio frequency heat affected micron size Fe3O4 powders: a bio-application perspective

Micron size Fe3O4 powders were chemically prepared and processed by radio frequency (13.56 MHz) oxygen plasma irradiation technique at different elevated temperatures using low radio frequency (RF) power level. Low magnetic field RF superconducting quantum interference device (SQUID) magnetization studies were performed up to a maximum magnetic field of 100 Oe, which was well below the magnetic field tolerance factor of human beings and at different temperatures (down to 5 K). Heat-treated powders in RF oxygen plasma showed significant changes in blocking temperature, magnetization and susceptibility, which are important parameters for bio-applications. It is observed that blocking temperature is decreased under identical RF heat treatment in oxygen plasma and noted to be dependent on average particle size. Microscopic rise in electron temperature during RF heating may likely to enhance the electron-hopping rate between Fe(+2) and Fe(+3) in the octahedral site of Fe3O4 molecular crystal structure, which in turn exhibit changes in blocking temperature including low field magnetization and susceptibility. These properties of Fe3O4 fine powder are likely to play important role in generating and processing biocompatible Ferro-fluid down to nanoscopic size for biomaterials applications.

Influence of doping rate in Er3+:ZnO films on emission characteristics

High-quality Er(3+):ZnO films were grown by the pulsed-laser deposition technique for 0.5 and 2 wt. % Er doping. Two peaks were observed at approximately 1.54 microm in the photoluminescence spectra of samples with 2 wt. % doping contrary to only one peak in the 0.5 wt. % doped sample. Both peaks were found to be strongly temperature dependent. The microscopic studies clearly illustrate that the appearance of the additional peak is attributed to the environment of Er(3+) ions in the form of ErO(6) clusters, which are optically active centers in the ZnO matrix. These results are very important for designing waveguides for telecommunications.

Effect of thermal plasma heating on the dielectric properties of Al-Zr composites

A low-cost extended arc thermal plasma heating (EATPH) source has been used for the sintering of Al-Zr high-temperature ceramic oxides, and their dielectric properties have been studied. Pellets of Al-Zr composites were sintered using optimum sintering parameters such as sintering time, plasma power and plasmagen gas flow rate in an EATPH reactor. Samples of similar composites were also sintered using a conventional resistive heating furnace at 1500°C for 20 h, and their dielectric properties were studied and compared with the plasma sintered sample. Sintered pellets were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and dielectric measurement, carried out as a function of frequency and temperature. Highly dense sintered products were obtained by the plasma heating route within a very short sintering time compared with the conventional sintering schedule. Dielectric measurements (both dielectric constant and loss factor) showed a significant reduction in the dielectric constant, K, at room temperature under different test frequencies and also as a function of temperature. However, the change in dielectric loss factor, tan Δ, was not as pronounced as the change in K. The behaviour of the K and tan Δ curves changes drastically compared with the conventional sintered material. The reduction in K and the crossover behaviour of tan Δ in the plasma sintered specimen may be due to the action of non-reactive Ar plasmagen gas during plasma sintering, which favours mobile oxygen for the polarization network under the influence of frequency and temperature.

Thyroiditis as a presenting feature of mumps

Thyroiditis complicating mumps is rare and occurs 1 week after the parotitis. A 9-year-old boy with a history of contact with a case of mumps presented with thyroid swelling. Thyroid scan showed a diffusely reduced uptake. The aspiration cytology showed lymphocytic thyroiditis. Thyroid function tests were normal and antithyroid antibodies were absent. Parotitis occurred 12 days after the onset of thyroiditis.

Knowledge, attitude and practices of parents of children with febrile convulsion

CONTEXT

Parental anxiety and apprehension is related to inadequate knowledge of fever and febrile convulsion.

AIMS

To study the knowledge, attitude, and practices of the parents of children with febrile convulsions.

SETTINGS AND DESIGN

Prospective questionnaire based study in a tertiary care centre carried over a period of one year.

SUBJECTS AND METHODS

140 parents of consecutive children presenting with febrile convulsion were enrolled.

STATISTICAL ANALYSIS USED

Chi-square test.

RESULTS

83 parents (59.3%) could not recognise the convulsion; 90.7% (127) did not carry out any intervention prior to getting the child to the hospital. The commonest immediate effect of the convulsion on the parents was fear of death (n= 126, 90%) followed by insomnia (n= 48, 34.3%), anorexia (n= 46, 32.9%), crying (n= 28, 20%) and fear of epilepsy (n= 28, 20%). Fear of brain damage, fear of recurrence and dyspepsia were voiced by the fathers alone (n= 20, cumulative incidence 14.3%). 109 (77.9%) parents did not know the fact that the convulsion can occur due to fever. The long-term concerns included fear of epilepsy (n= 64, 45.7%) and future recurrence (n= 27, 19.3%) in the affected child. For 56 (40%) of the parents every subsequent episode of fever was like a nightmare. Only 21 parents (15%) had thermometer at home and 28 (20%) knew the normal range of body temperature. Correct preventive measures were known only to 41 (29.2%). Awareness of febrile convulsion and the preventive measures was higher in socio-economic grade (P< 0.05).

CONCLUSIONS

The parental fear of fever and febrile convulsion is a major problem with serious negative consequences affecting daily familial life.

Neurofibromatosis-Noonan syndrome or LEOPARD Syndrome? A clinical dilemma

Neurofibromatosis (NF), Noonan syndrome (NS), and LEOPARD syndrome are all autosomal dominant conditions, each being a distinct clinical entity by itself. Rarely, one encounters cases with features of NF and NS and is termed as the 'Neurofibromatosis-Noonan syndrome' (NF-NS). The authors report a clinical dilemma with major clinical features of the NF-NS syndrome and LEOPARD syndrome co-existing in the same patient. Also, features of Noonan syndrome and LEOPARD syndrome are compared with the case reported.

Cri-du-chat syndrome: clinical profile and prenatal diagnosis

Prenatal diagnosis of cri-du-chat syndrome is described in 2 pregnancies. In Case 1, the mother was a balanced translocation carrier and had 2 previously affected off springs. Prenatal diagnosis by chorion villus sampling and cordocentesis was successful in diagnosing an affected conceptus and the pregnancy was electively terminated. Case 2 was referred for nonimmune foetal hydrops and cordocentesis revealed deletion 5p. This second case was noteworthy for the fact that deletion 5p has not been reported to cause foetal hydrops.