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The present study reports the temperature dependence of dielectric response of Ni doped MgTiO3 ceramics over a broad frequency range. (Mg1−x Ni x )TiO3 (x = 0.00–0.07) ceramics are prepared by a solid-state reaction process. The processing parameters are optimized to achieve maximum relative density. Among all the samples, (Mg0.95Ni0.05)TiO3 (MNTO) ceramics is exhibited the highest density with the best microstructure at 1300 °C. The optimum microwave dielectric properties (e r ~ 17.44, Q × f 0 ~ 181 THz) are displayed by the sample doped with x = 0.05 wt%. The detailed dielectric studies are performed on (Mg0.95Ni0.05)TiO3 composition in two different frequency ranges, 100 Hz–100 kHz at 298–358 K and 1–100 MHz at 133–503 K, respectively. A dielectric constant of 18.26 at 100 MHz is observed for (Mg0.95Ni0.05)TiO3 specimen at temperature 503 K. The frequency dependent conductivity is explained based on the basis of Jonscher power law. Further, the DC conductivity results obey the Arrhenius law, and the obtained activation energies are found to be 0.41 and 0.06 eV for (Mg0.95Ni0.05)TiO3 ceramics, measured at 100 MHz for high temperature (293–503 K) and cryogenic temperatures (133–293 K), respectively.

We report the effects of oxygen mixing percentage (OMP) and annealing temperature on surface morphology, optical, dielectric and electrical properties of (Mg0.95Ni0.05)TiO3 (MNT) thin films deposited onto amorphous SiO2 and platinized silicon (Pt/TiO2/SiO2/Si) substrates by radio frequency (RF) magnetron sputtering. The annealed films exhibited the highest refractive index, 2.05, at 600 nm with an optical bandgap value of 4.33 eV. The metal–insulator–metal (MIM) capacitors of the MNT thin films were fabricated under different OMPs and the dielectric properties were analyzed by using Maxwell–Wagner two-layer theory and Koop’s phenomenological theory. MNT films prepared under 50% OMP displayed the highest dielectric constant (11.21) and minimum loss tangent (0.0114) at 1 MHz. The impedance spectroscopy of the films deposited under 50% OMP has been studied. The Nyquist plots of MNT films revealed two semi-circular arcs and is explained on the basis of an equivalent circuit model. The frequency-dependent alternative current (AC) conductivity followed the Jonscher’s power law. The activation energies are calculated using the Arrhenius relationship. The hopping frequency of the charged species was calculated, and the correlation between AC and direct current (DC) conduction mechanisms established in accordance with the Barton–Nakajima–Namikawa (BNN) relationship.

Mg(Zr 0.05 Ti 0.95 )O 3 (MZT) thin films have been deposited onto amorphous SiO 2 and platinized silicon (Pt/TiO 2 /SiO 2 /Si) substrates by RF magnetron sputtering at different oxygen mixing percentages (OMP). The effect of OMP and post annealing temperature at 600 °C on crystal orientation, surface morphology, optical, electrical and dielectric properties of crystallined MZT films are investigated. A change of preferred orientation from (1 0 4) to (1 1 0) has been observed with increasing OMP from 0% to 100%. The preferred orientation growth has been explained on the basis of Lotgering model by calculating the orientation factor. The optical properties such as refractive index and bandgap were strongly influenced with O 2 content. It is also observed that the refractive index and packing density decreases with increasing OMP, leading to an enhancement in the optical bandgap from 4.19 to 4.52 eV. The dielectric constant and dielectric loss of the films ranged between 5.0–15.69 and 0.082–0.0135. The MZT thin films deposited at 100% OMP exhibited the high dielectric constant and low loss tangent. Further, the DC conductivity with frequency follows Jonscher law and the activation energy found to be 0.32 eV for MZT films deposited in pure oxygen atmosphere. Nyquist plots of MZT films revealed two semi circular arcs and are explained on the basis of equivalent circuit model. A series of two parallel RC combination in series fit with experimental data. The I – V characteristics reveals that the leakage current density decreases from 1.136 × 10 −8 to 4.69 × 10 −9 A/cm 2 for OMP, 0–100%, respectively for electric field strength of 200 kV/cm.

We report a systematic investigation on crystal structure, microstructure, and microwave dielectric properties of (Mg1−xCox)TiO3 (x = 0–0.07) ceramics prepared by semialkoxide precursor method. All the as-made samples exhibit an ilmenite structure with an incredible reduction in sintering temperature from 1350°C to 1200°C. Lattice parameter increases with increasing Co content due to the larger ionic radius of Co2+ as compared to Mg2+. The relative density, dielectric constant, and Q × f0 values increase with increasing Co up to 0.05 and decreases for x > 0.05. This is attributed to local lattice distortion, maximum relative density, and uniform grain growth. Q × f0 values were enhanced from 126 THz for x = 0 to a maximum value 170 THz for x = 0.05. A best combination of microwave dielectric properties (er ~ 17.03, Q × f0 ~ 170 THz @ 9.4 GHz and τf of −40 ppm/°C) was obtained for (Mg0.95Co0.05)TiO3 ceramic sintered at 1200°C for 3 h. The observed results reveal (Mg0.95Co0.05)TiO3 ceramic as one of the promising dielectric materials for low-loss and millimeter-microwave applications.

Aims: This cross-sectional study was designed to evaluate effect of sugar-sweetened beverages (SSBs) on semen parameters in infertile couples. Setting: Men attending infertility clinic. Design: prospective, observational study. Methods and material: Participants were assessed the type and frequency of SSB intake in the past month by a previously validated beverage intake questionnaire (BEVQ-15) and provided one semen sample for analysis. The primary outcome were semen parameters; namely volume (in mL), total sperm count (in millions/ejaculate), sperm concentration (in million/mL), sperm motility% (PRM+NPM+IM), progressive motility% (PRM), vitality% and sperm morphology% (per 200 spermatozoa). The main independent variable was SSB intake. Statistical analysis: Multiple linear regression models were used to predict semen parameters based on SSB intake and potential confounders, compared across quartiles using Kruskal-Wallis test. Non-linearity was examined by fitting models with linear and quadratic terms. Results: 385 men were included in the study. A significant decline in crude sperm motility% (P

Nano medicine is an emerging branch of pharmaceuticals, which is gaining considerable attention mainly due to its new and effective way of drug delivery. Various modes of drug delivery are still in their adolescent stage, polymer-based drug delivery system is one among these. In order to develop a novel and biocompatible nano-carrier for drug delivery through a “green” and, environmentally benign approach, herein, we report the design, synthesis and characterization of four novel pluronic-based amphiphilic copolymers. Candida antartica lipase was used to catalyze polymerization in the presence of molecular sieves under solventless conditions. The resulting copolymers were also investigated for their supramolecular organization and drug encapsulation capacity for biomedical applications.

The great synthetic flexibility of organosilicone polymers, their ease of processing, low cost, and nontoxic nature present an attractive alternative solution over current flame retardant materials. Novozyme-435 catalyzed amidation reaction with silicone-based oligomer was carried out to scale up the synthesis of co-polymer which was fully characterized from its detailed spectroscopic studies. Synthesized co-polymer was compounded in polyolefins for flame retardant applications. Nanoclay [Cloisite 20A, 2C18 MMT (dimethylditallowammonium-/dimethyldioctadecylammonium-modified montmorillonite)] was used as a potential additive in co-polymer, which was then blended with polyolefins to improve their thermal as well as flame retardant properties. The present work provides an initial exciting basis for the enzymatic synthesis of silicon based co-polymers in bulk and their flame retardant applications.

A postmenopausal lady with an in situ pacemaker developed a lump in the left breast and was diagnosed to have breast cancer. The patient underwent breast conservative surgery and was planned for post operative radiotherapy. The location of the tumor relative to the pacemaker provided a unique challenge in planning radiotherapy and the patient had an uneventful post radiotherapy course. A literature review revealed that modern generation pacemakers are very sensitive to radiation compared to their older counterparts. The present article makes suggestions towards reducing dose in radiotherapy planning in pacemaker patients.

Aim: To evolve a fast dose verification method for high-dose-rate (HDR) brachytherapy treatment plans and to demonstrate its applicability in different clinical cases. Materials and Methods: We developed a software tool in VC++ for the Varisource HDR unit for HDR dosimetry plan verification using TG-43 parameters. HDR treatment dosimetry of a number clinical cases using Varisource was verified by comparison with the treatment planning system (TPS). Results: A number of different types of clinical cases treated by Varisource were evaluated. TPS calculated dose values and verification code calculated dose values were found to agree to within 3% for most of the dose calculation points. Conclusions: We have validated with clinical cases a fast and independent dose verification method of the dosimetry at selected points for HDR brachytherapy treatments plan using TG-43 parameters. This can be used for the verification of the TPS calculated dose at various points. The code is written to work with Varisource, but it can conceivably be modified for other sources also by using the fitted constant of the respective source.

Purpose To evaluate the efficacy of systemic infliximab for the induction of remission in patients with retinal vasculitis, inadequately responsive to other immunomodulatory therapy, based on fluorescein angiography grading for retinal vasculitis evaluation. Methods We analyzed 60 patients with retinal vasculitis, from the Massachusetts Eye Research and Surgery Institution in Cambridge, MA. Response to therapy was based on analysis of serial fluorescein angiography and fundus photography, including a baseline angiogram before initiation of infliximab. Results Sixty patients received infliximab therapy between July 2007 and July 2012 at Massachusetts Eye Research and Surgery Institution for a diagnosis of retinal vasculitis. All had previously showed a poor clinical response to other immunomodulatory regimens, or ceased therapy due to intolerable side effects. The initial dose of infliximab was 5 mg/kg in all patients and remained at this dose for the extent of treatment in 57 (95%) patients. At 6 months, 45 of 51 (88.23%) patients were maintaining remission with therapy, 5 (9.8%) were in partial remission, and 1 patient had failed. At 12 months, 39 of 39 (100%) patients were maintaining remission with therapy. Conclusion Infliximab is effective for the treatment of recalcitrant noninfectious retinal vasculitis, refractory to conventional immunomodulatory therapy.

The purpose of this study was to investigate dosimetry (reproducibility, energy correction, relative response with distance from source, linearity with threshold dose, rate of fading, temperature and angular dependence) of a newly designed OneDosetrade mark MOSFET patient dosimetry system for use in HDR brachytherapy with Ir-192 energy. All measurements were performed with a MicroSelectron HDR unit and OneDose MOSFET detectors. All dosimeters were normalized to 3 min post-irradiation to minimize fading effects. All dosimeters gave reproducible readings with mean deviation of 1.8% (SD 0.4) and 2.4% (SD 0.6) for 0 degrees and 180 degrees incidences, respectively. The mean energy correction factor was found to be 1.1 (range 1.06-1.12). Overall, there was 60% and 40% mean response of the MOSFET at 2 and 3 cm, respectively, from the source. MOSFET results showed good agreement with TLD and parallel plate ion chamber. Linear dose response with threshold voltage shift was observed with applied doses of 0.3 Gy-5 Gy with Ir-192 energy. Linearity (R2 = 1) was observed in the MOSFET signal with the applied dose range of 0.3 Gy-5 Gy with Ir-192 energy. Fading effects were less than 1% after 10 min and the MOSFET detectors stayed stable (within 5%) over a period of 1 month. The MOSFET response was found to be decreased by approximately 1.5% at 37 degrees C compared to 20 degrees C. The isotropic response of the MOSFET was found to be within +/-6%. A maximum deviation of 5.5% was obtained between 0 degrees and 180 degrees for both the axes and this should be considered in clinical applications. The small size, cable-less, instant readout, permanent storage of dose and ease of use make the MOSFET a novel dosimeter and beneficial to patients for skin dose measurements with HDRBT using an Ir-192 source compared to the labour demanding and time-consuming TLDs.

Barium–strontium titanate thin films were prepared by the sol-gel (SG) method. The Barium–strontium titanate sol was derived from organometallic compounds and modified by pyrrole. The films derived from pyrrole were uniform and crack free. The structural evolution of the film was investigated by X-ray diffraction (XRD). The thickness of the film increased by twofold (645 nm) when pyrrole concentration was increased from 0 to 1.5 molar ratio with respect to titanium. Barium–strontium titanate films showed excellent UV absorption and transparency in the visible region. The direct band gap of barium–strontium titanate films was determined from the curve of absorption coefficient ( α ) vs. hν and was found to be 3.9 eV. The refractive index of the 500-nm-thick annealed film was 2.5. The dielectric constant and dielectric loss values of modified films annealed at 700 °C were 680 and 0.05, respectively, measured at 1 MHz. The dielectric constant increases and dielectric loss decreases, with increasing pyrrole concentration. The dielectric properties were also investigated with annealing temperature of barium–strontium titanate films. The grain size of the films varied with annealing temperature. The remanent polarization ( P r ) and coercive field ( E c ) of films made from the sol-gel method with pyrrole, were found to have average value of ≈2.2 μC/cm 2 and ≈21 kV/cm, respectively.

All rings are commutative with identity ( = 0) and a multiplicatively closed subset in a ring means a multiplicative monoid. All the standard notations and definitions are as in [2]. Let us recollect the following well-known result: If a is an ideal in a ring R and S is a multiplicatively closed subset of R such that S ∩ a = ∅, then there exists a prime ideal ℘ of R such that ℘ ⊇ a and ℘ ∩ S = ∅. Let I be a partially ordered set and R be a ring. Let {(ai , Si)}i∈I be a collection of pairs where ai is an ideal and Si is a multiplicatively closed subset in R such that ai ∩ Si = ∅. Bergman [2] has done a very close analysis of the problem

In studying unique factorization of domains we encountered a property of ideals. Using that we define the notion of almost prime ideals and prove that in Noetherian domains almost prime ideals are primary. We also prove that in a regular domain almost primes are precisely primes. Further, we define strictly nonprime ideals and study some inter relations between almost prime ideals, strictly nonprime ideals and factorization of ideals.

The 22-year-old conjecture is addressed which claims that any reachable matrix pair ( A , B ) from C [x] n×(n+m) is cyclizable, i.e. allows for F , u over C [x] s.t. ( A + BF ) k Bu , k =0,…, n −1, is a basis for C [y] n . It is shown that for a whole class of pairs the correctness of the conjecture is a consequence of the correctness of a conjecture on certain Toplitz pencils. An algebraic computable test for the validity of the latter is given. Based on these results the validity of the conjecture on cyclizability can be extended up to dimension 5.

The tape casting technique using a doctor-blade is used to fabricate thin dielectric sheets of barium strontium titanate (Ba1−xSrxTiO3) with x = 0.35 (abbreviated as BST). Initially, fine powder of Ba0.65Sr0.35TiO3 is prepared by the sol–gel method. Two kinds of tape are used for the stacks, i.e. (the direction of the layer is along the tape direction (in the casting direction)) and ⊥ (the direction of the layer is perpendicular to the tape direction (across the tape)). Further, two stacking sequences are used for stacking layers of tape, i.e. (the layers are in stacks in which all the layers are , abbreviated as the sequence) and (the layers are in stacks such that every other layer is perpendicular to the casting direction, abbreviated as the ⊥ sequence). Therefore, in the latter stacking sequence the top and bottom layers are always parallel to the casting direction and each ⊥ layer is sandwiched between two layers. It has been observed that the green density remains unaffected by any change of sequence. However, the density of fired tape cast BST changes significantly with change of sequence. For example, the density of multilayered BST with eleven layers is enhanced from ≈ 3.5 g cm-3 to ≈ 4 g cm-3 when the sequence changes from and ⊥. Observations of the microstructure of multilayered BST under the scanning electron microscope suggest that the packings of particles and pores are strongly dependent on the sequence. The dielectric permittivity of sintered tape cast BST is found to increase with increasing number of layers and temperature; however, it is higher for the ⊥ sequence. A comparison has also been made of the dielectric properties of tape cast BST derived from powders obtained from sol–gel and by conventional methods. Investigations on BST are highly desirable in relation to applications in multilayered capacitors in the electronics and communications industries.

This paper demonstrates the critical role of pH in the colloidal (i.e. sol-gel) synthesis of nano size α-Al2O3. Investigation, based on X-ray diffraction pattern, indicates that the transformation of α-Al2O3 from gels obtained at high pH⩾7, undergoes via formation of boehmite (gel→AlOOH→γ-Al2O3→α-Al2O3). On the other hand, the transformation of α-Al2O3 at low pH (⩽6) follows the gel→γ-Al2O3 →α-Al2O3 sequence. The transmission electron microscopy reveals that the particle size of the α-Al2O3 decreases from ≈750 to ≈70 nm with decreasing pH from 12 to 2.5, respectively. The α-Al2O3 with large surface area (≈130 m2/g) is obtained when it is processed at low pH (2.5). The true powder density of the α-Al2O3 sample derived at pH=2.5 is observed to be 3.92 g/cm3 after sintering at 1450 °C, due to fine particles. The isoelectric point (iep) and ξ of the α-Al2O3 are found to be 8.7 and 9.2 when synthesized at pH 2.5 and 12, respectively.

Let R[X] be a polynomial ring in one variable over a commutative ring R. If (R,ℳ) is a local ring then any Weierstrass polynomial in R[X] is contained only in the maximal ideal (ℳ,X) of R[X]. We generalise this property of Weierstrass polynomials and investigate properties of polynomials contained in a finite number of maximal ideals in R[X].

Lead zirconate titanate (PZT) thin films of thickness ≈2µm with a composition near the morphotropic phase boundary are successfully deposited on platinum-coated silicon substrates. The crystallization phase starts to appear at 500oC. The crystal structure, optical and electrical properties are investigated in relation to the thickness and annealing temperature of the films. The dielectric constant is observed to increase as thickness goes up to ≈1.28µm, and remains constant above that. At 700oC, the dielectric constant and dissipation factor of ≈ 2µm thick PZT film are ≈850 and ≈0.03, respectively. The film exhibits good optical transmissivity, and has a direct optical transition. The band gap of a film annealed at 700oC is found to be 3.34 eV. It has been observed that the n(λ) data can be fitted to a Sellmeier-type dispersion relation. Ferroelectric PZT shows almost no degradation in its polarization after 104 switching cycles at an applied voltage of 5 V. The results of this study confirm that ferroelectric PZT thin films are very useful for applications in a variety of devices such as ferroelectric memories and microelectromechanical systems.

An attempt was made to synthesize coiled carbon fibers over nickel catalyst using acetylene as a carbon source at 700 °C by microwave technique. X-ray diffraction (XRD) and temperature-programmed oxidation (TPO) studies showed presence of disordered carbon in these materials. Highly coiled carbon fibers were observed by scanning electron microscopy (SEM). From a transmission electron microscopy (TEM) study, the average diameter of the fiber was measured ≈200 nm. A Raman spectra of microcoiled carbon fiber was also recorded at room temperature under a nitrogen atmosphere. It has been observed that the surface area of the microwave derived microcoiled carbon was 62 m 2 g −1 . This value of surface area of microcoiled carbon was found to decrease with increasing temperature.

Let be a commutative local ring ( field). Then every ring automorphism of such that for all is the identity if and only if is algebraic over its prime field.

Europium doped ytrrium oxide (Eu:Y 2 O 3 ) was synthesized by a chemical wet method in the presence of tween-80 and ϵ -caprolactam in pH range 4–10. It has been observed that the variation in surface area, pore size, and pore volume of the final product, was strongly dependent on the initial pH of the solution. The powder with a large surface area (∼230 m 2 /g) and low pore diameter (∼16 nm) was obtained when the powder was processed at pH ∼4. The crystallite sizes of the powders processed at pH ∼4 and 10, were found to be 35 and 198 nm, respectively. The structural, chemical and thermal studies of the powders were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectrophotometer (FTIR), Carbon analyzer and Thermogravimetry (TGA). High resolution transmission electron microscopic (HRTEM) study of heat treated powders showed a polygonal morphology with particle size of 40 nm when powder was derived at pH ∼4. Observations of fluorescence suggested that the 5 D 0 → 7 F 2 transition within europium was found to be highly dependent on the initial pH.

To assess the role of pelvic plexus block (PPB) in reducing pain during transrectal ultrasonography(TRUS)-guided prostate biopsy, compared with the conventional periprostatic nerve block (PNB).A prospective, double-blind observational study was conducted with patients being randomised into three groups. Group-1 (47 patients) received intrarectal local anaesthesia (IRLA) with 10 mL 2% lignocaine jelly along with pelvic plexus block (PPB) with 2.5 mL 2% lignocaine injection bilaterally. Group-2 (46 patients) received IRLA with periprostatic nerve block (PNB). Group-3 (46 patients) received only IRLA without any type of nerve block. The patients were requested to rate the level of pain from 0 to 10 on a visual analogue scale (VAS) at two time points: VAS-1: during biopsy procedure and VAS-2: 30 min after the procedure.The mean age of the patients, mean volume of the prostates and mean serum PSA values were comparable among the three groups. The mean pain score during biopsy was significantly less in the PPB group [mean (range) sore of 2.91 (2-4)] compared with the PNB group [mean (range) score of 4 (3-5)], and both these groups were superior to the no nerve block group [mean score of 5.4 (3-7)]. There was no significant difference between the mean pain scores, 30 min after the procedure among the three groups with the mean (range) scores being 2.75 (2-4), 2.83 (2-4) and 2.85 (2-4), respectively.PPB is superior to conventional periprostatic nerve block (PNB) for pain control during TRUS-guided biopsy and both are in turn superior to no nerve block.

In this paper, the dielectric and piezoelectric properties of sol-gel derived and microwave sintered PZT are presented. It has been observed that the microwave sintering results in a material with a higher dielectric constant (≈1600) than that sintered by conventional methods (≈1480). It also offers a low dielectric loss tangent and improved d33. Pellets sintered by the microwave method at 1100 °C are found to have high hardness (≈1460 MPa) on the Vickers hardness scale with a theoretical density of ≈94% in comparison with that sintered by the conventional method (i.e. ≈980 MPa and ≈84%). From a hysteresis study, the remanent polarization (Pr) and coercive field (Ec) of the microwave sintered PZT are observed to be 340 mC m-2 and 10 kV cm-1, respectively. The value of Ec in the microwave sintered sample is low and this property is desirable for device fabrication of PZT-based smart structures.

g-MnOOH was synthesized by hydrothermal method at low temperature in the presence of tetraethyl ammonium wx wx hydroxide TAH . The phase of the final product was observed to be sensitive for the concentration of TAH . g-MnOOH appeared as a pure and single phase, for the concentration range from 0.1 to 0.5 mole with respect to Mn. The powder prepared was found to have fiber morphology with a high surface area of 71.8 m 2 rg. Thermal and chemical analysis of wx g-MnOOH have been made by TGArDTA, FTIR and DCP. This study indicates that the concentration of TAH affects the conductivity of the powder. The conductivity was explained in terms of the phase obtained in the final product after hydrothermal treatment. q 2001 Elsevier Science B.V. All rights reserved.

A novel procedure for the synthesis of uniform europium doped yttria powder was developed. It was prepared by chemically growth-controlled method in the presence of surface modifier. A mixture of Tween-80 (polyoxyethylene (20) sorbitate) and β-alanine, was used as surface modifier. The obtained powder was pure and highly crystalline. The powder was also examined via Fourier transformation infra red (FTIR) spectroscopy to determine the presence of nitrate ions along with the powder at pre and post calcination. Thermal behavior of the powder was investigated by thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). High Resolution Transmission Microscopy (HRTEM) reveals that the particle size is around 22 nm. Chemical microanalysis of europium doped yttria was made by energy dispersive spectrum analyzer (EDS) attached along with HRTEM and indicated a Y/Eu atomic ratio 2.1. The fluorescence spectra of calcined powder showed that the Eu3+ ions were in low symmetry bonding sites in the yttria structure.

This investigation presents a novel method of preparation of barium strontium titanate (BST) from [Ba(2,4-pentadionate)-Sr(2,4-pentadionate)-Ti(OC3H7)4-TEA-i-PrOH-water] system. Triethanolamine (TEA) was used as an additive, which prevents the precipitation of oxides from the alcoholic titanium isopropoxide solution in the presence of excess water. An increasing molar ratio of water from 4.5 to 6.5 did not show any precipitation in the precursor sols in the presence of triethanolamine. Thermal behavior of the xerogel was studied by thermal gravimetric analysis (TGA). X-ray diffraction (XRD) indicated that the pure BST phase was crystallized at 900 °C. Triethanolamine was observed to influence the porous behavior of the final powders. Pore diameter of the powder calcined at 900 °C, was increased from 0.013 μm to 0.080 μm when the molar ratio of triethanolamine increased from zero to four. Therefore, a porous powder of BST was obtained at a higher molar ratio of triethanolamine. Porous behavior was also stu...

Nano- and micro-coiled carbon fibers find applications in electronic devices, electromagnetic absorbers and filters. Smart devices can be conceived using tunable films on these fibers and tunable host materials. A new method of producing helical carbon fibers with dimensions in the order of less than a micrometer has been developed using microwaves. The microwave CVD system presented here eliminates the use of the toxic impurity gas, which is required in the conventional method. Both methods involve gas phase reactions over a substrate seeded with an appropriate catalyst. Micro-coiled carbon fiber (MCCF) was grown by the catalytic pyrolysis of acetylene on a silicon carbide substrate on which nickel metal powder was dispersed as a catalyst. Various factors, for example flow rate of the gas, particle size of the catalyst, effect of reaction temperature and time, were studied in order to understand the growth of the microwave synthesis of MCCF. MCCFs were also synthesized by a conventional method in the presence of thiophene as an impurity gas so that a comparison can be made with the materials obtained by the microwave system. The morphology of the final products were investigated by scanning electron microscopy. The carbon products obtained by traditional and microwave methods were investigated with the help of x-ray diffraction. The effect of various reaction conditions on the morphological development of a MCCF were examined in detail. Furthermore, a brief study was made on the microwave absorbing property of the MCCF.

NiO-based xerogels were prepared by sol-gel processing starting from the NiCl2-BuOH-H2O system. Structural features associated to the porosity of xerogels were studied by small-angle X-ray scattering. Xerogels heat-treated at low temperatures (423 and 573 K) are composed of hydrated NiCl2 small crystals and exhibit an essentially single mode nanoporous structure with an average pore radius of ∼75 Å. Xerogels heat-treated at 973 and 1173 K are composed of aggregates of NiO crystals which only contain intergrain mesopores with radii exceeding 200 Å. A mixture of phases is observed in xerogels heat-treated at 773 K. Xerogels with a water concentration of 2 mol/(mol NiCl2) exhibit a narrow nanopore size distribution. Water concentrations higher or lower than 2 mol promote the formation of nanoporous structures with wider size distributions.

The concept of tailored interfaces has been applied to the synthesis of Eu 2 O 3 /Y 2 O 3 powders to achieve a narrow size distribution by using a modifier. It was found that the particle size gradually decreased from 6 μm to 10 nm with an increase in concentration of the modifier from 0 to 10 wt% with respect to Eu 2 O 3 /Y 2 O 3 . Fluorescence spectra of the sample containing 10 wt% of surface modifier showed approximately a 5-fold enhancement of emission intensity of the 5 D 0 → 7 F 2 transition of Eu 3+ . This transition is the characteristic transition of europium for red fluorescence under UV light excitation. The concentration dependence of fluorescence in the range from 0–5 mol% Eu 2 O 3 did not reveal any concentration quenching.

The sol-gel route to glasses and ceramics has attracted an increasing amount of scientific and technological interest recently. In this process, sols with different concentrations are used as precursors for xerogels and to produce materials that consist of fine oxide particles. In the present work, nickel hydroxide gels have been obtained via the hydrolysis of a molecular precursor in the presence of acetic acid. The chemical aspects of the material transformation have been studied by using Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) for different acetic acid contents and several heat-treatment temperatures. The carboxylic acid acts as a ligand at a molecular level in the precursor, therefore modifying the entire hydrolysis and condensation process. Small-angle X-ray scattering (SAXS) studies and density measurements have been performed for the structural characterization of the xerogels. A denser, final oxide material is obtained when a higher acetic acid concentration is used. The porosity of the dry gels coarsens when they are heat-treated up to a temperature of ∼400°C and its density decreases. The material that has been heat-treated up to a temperature of 800°C densifies and exhibits a finer porosity. The chemical properties at a molecular level satisfactorily explain and are well correlated with the structural characteristics of the studied material.

In this work, sol–gel and dip-coating methods were used to produce nickel oxide/hydroxide films. Strips of glass previously coated with transparent/conducting films of SnO 2 were utilized as substrates. The nickel oxide films were obtained by wetting the substrates in a solution of NiCl 2 ·6H 2 O in butanol and ethylene glycol. The dried gel films were found to be transparent and moisture sensitive. X-ray diffraction analysis (XRD) was performed to identify the produced compounds of heat-treated samples. A significant effect of temperature and time on the film's thickness was observed. Simultaneously, chemical analysis, e.g. carbonaceous matter and water, were examined by DSC and FTIR spectroscopy. Transmittance measurements were performed in the range of 350 nm to 850 nm in the films at different optical states. The coloration/bleaching process was found to be reversible. The cyclic voltammetry shows broad peaks related to Ni(II)/Ni(III) and Ni(III)/Ni(IV) oxidation/reduction processes. The measurements are discussed in detail in terms of the temperature effect.

Objectives: To describe an approach based on initial tissue-conserving surgery used to obtain histologically determined prognostic information that has therapeutic implications and the potential to enhance preservation of function. Study Design: Analysis of a group of patients with head and neck cancer treated initially with tissue-conserving surgery based on Mohs' histographic sectioning and selected neck dissection to derive histologically determined prognostic information with therapeutic implications and preservation in function. Methods: This study is primarily based on an analysis of patients from January 1, 1989, through June 4, 1996 assigned to a protocol evaluating resection of oral cavity squamous cell cancer with margin control using Mohs' histographic technique and/or a group of patients with neck assessment of NO on clinical examination who are undergoing supraomohyoid neck dissections. Results: Thirty-three primary tumor resections were performed using the Mohs' technique, and 54% required two or more Mohs' sections before clear histologic margins were obtained following resection based on clinically determined negative margins. There were 44 patients who underwent unilateral or bilateral supraomohyoid neck dissections, and 33% had occult, histologically positive nodes. When compared with the disease of the neck specimens, a preoperative computed tomography scan had a sensitivity of 25%, a specificity of 77%, and an accuracy of 63%. Conclusions : This report describes the effectiveness of Mohs' histographic sectioning and selective neck dissection as a means of determining prognostic information that can be used to develop a focused and cost-effective treatment program that, along with contemporary reconstructive techniques, provides a potential enhancement of function preservation.

Let R be a commutative ring with identity. Consider R as a simple graph with vertices elements of R where any two distinct elements x, y ϵ R are adjacent if and only if xy = 0. Beck [2] conjectured that ℵ(R) =c1(R), for all colorings R. Anderson and Naseer [1] provided a counter example to the conjecture i.e., gave an example of a non-chromatic ring. This paper generalizes the example and gives a large class of non-chromatic rings [Theorem 1.1]• A detailed analysis of the graph of these rings is also provided.

In [3], a class of non-chromatic finite local rings (R,m) is given. It is proved that if R has prime residue field Fp and p ≥ 3,then , moreover,χ(R)=p2+2 for p = 2,3,5. Here we have shown that, in general, χ(R)≠p2+2 by showing that χ(R)=p2+3 for p = 7.

alpha-Alumina and boehmite particles were synthesized by coprecipitation followed by a hydrothermal treatment. X-ray diffraction (XRD) indicated that alpha-Al2O3 was the major phase and coexisted with 4% of boehmite in the presence of the alpha-Al2O3 seeds. On the other hand, a single boehmite phase was obtained in the absence of the alpha-Al2O3 seed particles. The powder densified in the temperature range from 1050° to 1350°C. High-resolution transmission electron microscopy (HRTEM) showed that the particle size of the synthesized alpha-Al2O3 was 60 nm. The surface area was 245 m2/g.