To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Nitridation of GeO2 interfacial layer (IL) was done using continuous wave (CW) and pulsed wave (PW) decoupled plasma nitridation (DPN) processes. Langmuir probe analysis of the N2 plasma demonstrates that at the same effective power and pressure, PW plasma has similar electron density (Ne) with lower electron temperature (kTe) and plasma potential (Vp) as compared to CW plasma. This results in softer plasma conditions using a PW process leading to lower plasma-related damage in the IL, but without reducing the overall nitrogen concentration. The plasma parameters were further correlated to mobility (μ) and interface trap density (Dit) extracted from fabricated Ge n-MOSFETs. As expected from the plasma analysis, at the same effective power and pressure, the PW DPN process shows 1.2X higher electron mobility as compared to a CW process. This improvement can enable GeON as an IL for future Ge CMOS gate stack technology.
Eu3+/Tb3+co-doped YBO3 three-dimensional (3D) microstructures have been hydrothermally prepared by adjusting solvent and the molar ratio of Y3+ to B (Y/B) at 180 °C. The whole process was carried out under alkaline conditions without the use of any surfactant or catalyst. Characterizations of the samples are carried out using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The photoluminescence (PL) colors of YBO3 sample co-doped with Eu3+ and Tb3+ under ultraviolet excitation can be tuned from red, through yellow and green-yellow, to green by changing the relative doping concentrations of the two activator ions. These phosphors with multicolor emissions in the visible region be potentially used as labels for light-display systems, optoelectronic devices and biological molecules.
The Bunsen-Roscoe law states that the effect of radiation is always the same regardless of the variation in the intensity or in the time of radiation as long as the product of the two is kept constant. This law holds true for many ordinary physico-chemical reactions over a wide range of intensities. The present investigation was undertaken to test the validity of the Bunsen-Roscoe law by studying the frequency of (1) sex-linked lethal mutations and (2) translocations in Drosophila melanogaster at much lower intensities of radiation than those previously tried.
A combined approach, using solid state NMR and Molecular Dynamics (MD) simulations, has been employed in this work to investigate fluoride-ion motion in the PbSnF4 family of anionic conductors, materials that contain double layers of Sn2+ and M2+ cations. 19F MAS NMR spectra of PbSnF4 and BaSnF4 show that the fluoride ions are mobile on the NMR timescale (10−4 s), even at room temperature. In the case of BaSnF4, two different groups of fluoride ions were observed, one group corresponding to fluorine atoms between the layers of Ba2+ cations, and the other set, corresponding to mobile fluoride ions undergoing exchange between sites in the Ba-Sn and Sn-Sn layers. The 119Sn NMR suggests a highly distorted Sn environment in these compounds, consistent with the presence of stereoactive Sn lone pairs. MD simulations, using the Polarizable Ion Model, have been carried out to probe the conduction mechanism. These simulations are able to reproduce elements of the structure such as the reduction in the occupancy of the fluorine ions between the Sn-Sn layers. Anisotropic conductivity, involving primarily motion in the M-Sn layers, is predicted, consistent with the NMR results. In the case of BaSnF4, no motion involving the fluoride ions in the Ba-Ba layers is observed on the simulation timescale (10−12 s) and a cyclic mechanism of fluoride-ion motion involving two types of fluoride ions in the Ba-Sn layers is proposed.
Four series of samples, prepared at 250° C by decomposition of a mixture of silane and argon in a radio frequency powered deposition systems (rf-PECVD), have been studied. The dilution rates were 1 %, 1.5 %, 5 % and 10 % of silane in argon and the total pressure was 0.5 Torr for the first series and 0.2 Torr for the others. Structural and transport properties of the materials have been studied as function of power density. Structural studies show the transition from purely amorphous material towards microcrystalline material with increasing rf power density. The transport parameters were measured in the as-deposited, light-soaked and annealed states and compared to those obtained on state of the art material. The best material obtained is clearly device grade material. This study shows that argon dilution allows to tailor the material for a given application.
Planar strain in CaF2 and Ge/CaF2 films grown on (111) Si substrate has been measured by an x-ray double crystal diffraction technique using rocking curves. The films grown by a solid phase epitaxial approach using in situ rapid isothermal processing are found to have small tensile planar strain.
A dynamical x-ray diffraction theory has been used to obtain microscopic strain profiles in thin Au/Ni multilayers. Depth profiles of strains in these multilayers, with repeat periodicities varying from 0.82 nm to 9.0 nm, are obtained by an iterative fitting of the calculated diffraction pattern with the experimental one. Interfacial coherency is found to play an important role in understanding the origin of the supermodulus effect in metallic multilayers.
Soft X-ray photoelectron spectromicroscopy has been employed to examine the microstructural chemistry of corrosion on thin films of AL-i%Cu-1%Si alloy. Cu-rich precipitates are formed after the film is annealed at around 320ºC Localized corrosion takes place around these precipitates, and circular microstructures have been observed. Energy distribution curves (EDCs) taken at specific points are analyzed and photoelectron images were obtained from different kinetic energies corresponding to the peaks in EDC. It was found that after corrosion the Al2Cu particles are revealed and distributed at the center of the corrosion structure with oxide as matrix, while the oxides form a ring-like band outside.
The structure, composition and strain in Ni/Ti multilayers are analyzed using x-ray diffraction theories. The repeat period of the multilayers used in this study ranges from 1.3 to 12.8 nm. The composition modulation is obtained by using a kinematical theory of x-ray diffraction. A sine wave for the shorter repeat period and a rectangular wave for the longer repeat period are predicted for the composition modulation. The strain within each atomic layer is found by iteratively fitting the experimental x-ray diffraction pattern with the simulated one from a dynamical theory of x-ray diffraction. The strain at the interface is tensile in Ni and compressive in Ti with a complete relaxation of the strain at a distance away from the interface.
Isothermal compression tests were conducted on a particulate reinforced Ti-44Al–3V+7.5v/o TiB2 composite produced by the XD® process over wide ranges of temperatures and strain rates, 1050 to 1300 C and 0.001 to 1.0 s-1, respectively. Flow localization parameter analysis was performed to analyze the flow behavior of the composite under various processing conditions, and the results were compared to those by dynamic material modeling. Microstructural characterization was also conducted to correlate the flow behavior with post-deformation microstructures. With combined information on flow behavior and microstructures, the processing condition for relatively stable flow and uniform microstructure was determined to be 1300 C and 0.01 to 0.1 s-1.
We have studied the structural evolution in amorphous and microcrystalline silicon deposited from silane-argon mixture by radio frequency plasma enhanced chemical vapour deposition (PECVD) method. Sharp increase in small angle x-ray scattering (SAXS) intensity, in accordance with tilt measurements, indicates columnar morphology in the sample deposited in the amorphous-microcrystalline transition region. The variation of SAXS measured heterogeneity and a gradual shift of Si-H stretching vibrational frequency at 2000 cm-1 towards higher wave number with increase of power density indicate structural modifications in the films. Observation of sharp increase in the ratio of the intensity of Ar* to SiH* in the transition region may explain the surface modification assisted by Ar* and hence the structural changes in the material.
Wild apricot (Prunus armeniaca L.) is an economically important fruit crop for folk and marginal farmers and local tribal populations in the high-altitude difficult terrains of north-western Himalayas in Jammu and Kashmir and Himachal Pradesh states of India. This is a multi-purpose fruit tree species which, besides its fresh edible fruits, is preserved for use in diverse ways depending upon the type of cultivar. Seed kernel of apricot is used as edible nut and for the production of edible oil. In the present study, 147 diverse accessions of wild and cultivated apricot belonging to 28 folk cultivars were collected and characterized for fruit, stone and kernel characters. Indigenous traditional uses and importance of fruits and kernels of these folk cultivars have been recorded and described. Promising table-type cultivars identified were Margulam, Lodi, Shakarpara, Narmo and Khurmani, while drying-type cultivars were Halman, Shakarpara, Rakchey Karpo and Tachu. Cultivars Chuli and Shadi were the most common types and widely distributed with vast variability, while other cultivars had localized presence. Some of these folk cultivars have high potential for promotion as commercial cultivars of apricot in this high-altitude area basically depending upon traditional production system. Genetic resource management including collection, characterization and documentation of existing variability of apricot is of immense importance for safe conservation and commercialization of potential cultivars to enhance farmer's livelihood in this fragile agroecosystem.
This paper is concerned with an axially symmetric frictionless contact between an elastically transversely isptropic functionally graded half-space and a rigid base that has a small axisymmetric surface recess. The graded half-space is modeled as a nonhomogeneous medium. We reduce the problem to solving Fredholm integral equations, solve these equations numerically and establish a relationship between the applied pressure and gap radius. The effects of anisotropy and nonhomogeneity parameter of the graded half-space on the normal pressure as well as on the critical pressure have been shown graphically.
Elastic behaviour of a nonhomogeneous transversely isotropic half-space is studied under the action of a smooth rigid axisymmetric indentor. Hankel transforms of different orders have been used. It is observed that in contrast to a homogeneous medium, the pressure distribution in the contact region in a nonhomogeneous medium is not directly available, rather it is obtainable from the solution of a Fredholm integral equation. The integral equation is solved for a flat-ended punch and paraboloidal indentations for various values of the nonhomogeneity parameter, and the effects of nonhomogeneity in elastic behaviour on stresses have been shown graphically. The results of the associated homogeneous case are readily available from the results of the present study.
A new genus, Coffmania in the tribe Pentaneurini of the subfamily Tanypodinae with two new species from Darjeeling-Sikkim Himalayas in India is described and illustrated with male and female imagines, pupa and larva. Systematics of the genus and ecology of the species have also been discussed.
A 56-year-old man presented with the difficulty of swallowing and respiratory distress due to a large tumour arising from the tongue and occupying the entire oral cavity. Histological examination revealed it to be an extraskeletal osteogenic sarcoma. The tumour was excised. After six weeks, he came back with massive local recurrence and bleeding from the tumour, but died despite chemotherapy. Review of the literature revealed only four other such cases of this rare tumour. A brief review of these four cases is also made.
Semiconducting Bi1−xPbxBaO3−δ (or BPB) glasses with x = 0 to 0.8 have been prepared by fast quenching from the melt. Interesting anomalies in the temperature-dependent polaronic conductivity and dielectric constant have been observed in all these glass compositions at temperatures, Tp, varying from 310 to 330 K (depending on Pb concentration). This nonlinear behavior is considered to be associated with the local ordering or the displacements of the BiO3 type pyramidal structural units present in the glass matrix (observed from the infrared spectra of these glasses). This type of ordering/displacement gives rise to a local instability in the glass network structure which is also supported by the observed heat capacity anomaly around the same temperatures Tp.
Hoarseness of voice due to paralysis of the left recurrent laryngeal nerve caused by a dilated left atrium in mitral stenosis as discussed by Ortner, is a subject of controversy. Different authors have cited different mechanisms as explanation. A variety of cardiac problems such as primary pulmonary hypertension, ischaemic heart disease, various congenital heart disorders can all lead to paralysis of the left recurrent laryngeal nerve. Most authors believe that pressure in the pulmonary artery causes the nerve compression. In Papua New Guinea cor pulmonale and rheumatic heart disease are the commonest cardiac disorders seen. Ortner's syndrome is a rarity and has never been reported from here before. Here three different case reports are presented with mitral stenosis, primary pulmonary hypertension and combined mitral stenosis and regurgitation and the pathogenesis of hoarseness is discussed.
The immatures (larva and pupa) of Rheocricotopus (Psilocricotopus) valgus Chaudhuri & Sinharay are described for the first
time. The species belongs to chalybeatus group. The larva is opportunistic, present in the fast-flowing streams to slow-flowing
organically enriched sewage drains. It lives in tunnels made of various particles glued together by silky secretions. There are two
generations a year with peak emergence in April-May and September-November. The sex ratio of females to males is 2:1.