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There is an increasing need for integrating high dielectric constant ceramic thin film components in organic and 3D IC packages to lower the power-supply impedance at high frequencies and supply noise-free power to the ICs. Sol-gel approach is very attractive for high density capacitors because of its ability to precisely control the composition of the films and the ease of introducing dopants to engineer the dielectric properties such as breakdown voltages and DC leakage characteristics. Thin films on copper foils lend themselves to organic package integration with standard foil lamination techniques used in package build-up processes. However, fabrication of thin film barium titanate on copper foils is generally affected by process incompatibility during crystallization in reducing atmospheres, leading to poor crystallization, oxygen vacancies and copper diffusion through the film that degrades the electrical properties.
This paper focuses on the dielectric properties and electrical reliability of thin films on copper foils. Thin film (300-400 nm) embedded capacitors with capacitance density of 2 μF/cm2, low leakage current and high breakdown voltage were fabricated via sol-gel technology and foil lamination. To lower the leakage current, the chemical composition was altered by incorporating – 1.) Excess barium 2.) Acceptor dopants such as Mn. Both approaches lowered the leakage current compared to that of pure barium titanate. SEM analysis showed enhanced densification and refined grain structure with chemistry modification. The films showed good stability in leakage currents at 150 C with an applied field strength of 100 kV/cm, demonstrating the electrical reliability of these films.
To compare endoscopic assisted powered adenoidectomy with conventional curettage adenoidectomy.
A randomised controlled trial was conducted at a tertiary care teaching hospital. Fifty patients with a symptom complex pertaining to adenoid hypertrophy and requiring adenoidectomy were chosen and divided into 2 groups of 25 each. Patients in group A underwent conventional curettage adenoidectomy and those in group B underwent endoscopic assisted powered adenoidectomy. Comparison was based on the parameters of surgical time, intra-operative bleeding, post-operative pain and completeness of adenoid removal.
The surgical time was significantly longer with the powered instrument. Mean blood loss was greater in the powered group, but was statistically insignificant. The powered procedure fared significantly better, with lower pain scores and more instances of complete tissue resection.
A curved microdebrider blade can be used safely and precisely for adenoidectomy under endoscopic vision. It enables complete resection of adenoid tissue. This method also proves to be an excellent teaching aid.
Many studies have identified changes in the brain associated with obsessive–compulsive disorder (OCD), but few have examined the relationship between genetic determinants of OCD and brain variation.
We present the first genome-wide investigation of overlapping genetic risk for OCD and genetic influences on subcortical brain structures.
Using single nucleotide polymorphism effect concordance analysis, we measured genetic overlap between the first genome-wide association study (GWAS) of OCD (1465 participants with OCD, 5557 controls) and recent GWASs of eight subcortical brain volumes (13 171 participants).
We found evidence of significant positive concordance between OCD risk variants and variants associated with greater nucleus accumbens and putamen volumes. When conditioning OCD risk variants on brain volume, variants influencing putamen, amygdala and thalamus volumes were associated with risk for OCD.
These results are consistent with current OCD neurocircuitry models. Further evidence will clarify the relationship between putamen volume and OCD risk, and the roles of the detected variants in this disorder.
Declaration of interest
The authors have declared that no competing interests exist.
This paper investigates the synergies and trade-offs between passive aeroelastic tailoring and adaptive aeroelastic deformation of a transport composite wing for fuel burn minimisation. This goal is achieved by optimising thickness and stiffness distributions of constitutive laminates, jig-twist shape and distributed control surface deflections through different segments of a nominal “cruise-climb” mission. Enhanced aerostructural efficiency is sought both passively and adaptively as a means of aerodynamic load redistribution, which, in turn, is used for manoeuvre load relief and minimum drag dissipation. Passive shape adaptation is obtained by embedding shear-extension and bend-twist couplings in the laminated wing skins. Adaptive camber changes are provided via full-span trailing-edge flaps. Optimised design solutions are found using a bi-level approach that integrates gradient-based and particle swarm optimisations in order to tailor structural properties at rib-bay level and retrieve blended stacking sequences. Performance benefits from the combination of passive aeroelastic tailoring with adaptive control devices are benchmarked in terms of fuel burn and a payload-range efficiency. It is shown that the aeroservoelastically tailored composite design allows for significant weight and fuel burn improvements when compared to a similar all-metallic wing. Additionally, the trailing-edge flap augmentation can extend the aircraft performance envelope and improve the overall cruise span efficiency to nearly optimal lift distributions.
Perovskite materials are sensitive to environmental conditions. Here we report the synthesis and characterization of a hydrophobic alkylammonium lead(II) iodide perovskite with enhanced stability in water. Water stability was achieved by growing a shell of 4-[(N-3-butyne)carboxyamido]anilinium lead(II) iodide over methylammonium lead(II) iodide. As a proof of concept, the water-splitting reaction was performed using our new material coated on TiO2, and a 7-fold increase in applied bias photon-to-current efficiency was observed as compared with standard p25-TiO2. Such simple and versatile chemical modification to induce high water stability is useful toward exploring new applications for the perovskite materials.
An outbreak of gastroenteritis affected 453 attendees (attack rate 28·5%) of six separate events held at a hotel in Singapore. Active case detection, case-control studies, hygiene inspections and microbial analysis of food, environmental and stool samples were conducted to determine the aetiology of the outbreak and the modes of transmission. The only commonality was the food, crockery and cutlery provided and/or handled by the hotel's Chinese banquet kitchen. Stool specimens from 34 cases and 15 food handlers were positive for norovirus genogroup II. The putative index case was one of eight norovirus-positive food handlers who had worked while they were symptomatic. Several food samples and remnants tested positive for Escherichia coli or high faecal coliforms, aerobic plate counts and/or total coliforms, indicating poor food hygiene. This large common-source outbreak of norovirus gastroenteritis was caused by the consumption of contaminated food and/or contact with contaminated crockery or cutlery provided or handled by the hotel's Chinese banquet kitchen.
We present the first results from multi-site observations of the δ Scuti star XX Pyx (CD–24°7599). The observations were carried out as the 17th run of the Delta Scuti Network. We collected 583 hr of B, V time-series photometry, resulting in a detection level (4σ) in the amplitude spectrum of 0.5 mmag. We detect 6 new pulsation frequencies, bringing the total number of frequencies known in this star up 19.
In this paper, we report on the selective area growth (SAG) of GaN directly on patterned c-plane sapphire substrates by hydride vapor phase epitaxy (HVPE). A number of researchers have reported that the HVPE growth technique, unlike the MBE and MOCVD methods, is capable of producing device quality GaN films without the need for any low temperature nucleation/buffer layers. The density of edge dislocations in these HVPE films decreases dramatically as the film thickness is increased, and the dislocation density values for thick films (> 10μm) are comparable to those reported for the best GaN films grown by other methods on c-sapphire. These advantages of the HVPE growth technique makes it possible to achieve high quality selective area growth of GaN directly on c-sapphire substrates.
C-plane sapphire substrates were coated with PECVD SiO2 and photolithographically patterned with different size and shape openings. Subsequently, these patterned substrates were introduced in a horizontal, hot-wall quartz reactor for the GaN growth. It was observed that single crystal GaN growth was preferentially initiated in the openings in the oxide layer. This selective area growth was followed by epitaxial lateral overgrowth (ELO), leading to the formation of hexagonal GaN prisms terminated in smooth, vertical (100) facets. We have been successful in shearing these pyramid structures from the sapphire substrates as individual devices, which do not require any post-growth etching for feature definition. This procedure allows for the dramatic reduction of the process complexity and the duration and expense for GaN growth for device applications. Stimulated emission results on these self-formed optical cavities are also presented.
Single walled carbon nanotubes (SWNTs) possess unique structural and functional properties. Their ability to be functionalized with different biomolecules makes them excellent candidates for biomedical applications like targeted drug delivery and cancer diagnostics. However, prior to use in therapeutic applications, biocompatibility of SWNTs needs to be thoroughly investigated. Blood is a living tissue and contains cells which can potentially interact with SWNTs during the drug delivery process. The interaction of leukocytes in blood with the SWNTs can provide information regarding the immune response of the host to the nanotubes. Here, we evaluated the acute immune response of leukocytes in blood to SWNTs via (a) direct interaction, due to the presence of SWNTs in circulation and (b) indirect interaction, due to the presentation of SWNTs to leukocytes via antigen presenting cells. These SWNTs were non-covalently functionalized with single stranded DNA (ss-DNA) that acts as a surfactant for suspending SWNTs in aqueous solutions and also serves as a backbone for attaching and transporting different biomolecules. Isolation of cells from blood was done using density gradient centrifugation. Early activation markers were used to study the activation of different leukocyte subpopulations and any activation results in changes of these markers. Flow cytometry was done to analyze the different subpopulations. Results of our study demonstrated that ss-DNA functionalized SWNTs do not elicit an immune response from leukocytes in blood via direct or indirect interaction. This intensive study demonstrates the biocompatibility of single walled carbon nanotubes and paves the way for their safe use in drug delivery and cancer therapeutics without cytotoxicity.
Tensile tests were conducted on an extruded Ni-30(at.%)Al-20Fe-0.05Zr intermetallic alloy in the temperature range 300–1200 K and the microstructures were characterized by optical, scanning and transmission electron microscopy. The alloy did not exhibit any room temperature ductility and failed by transgranular cleavage at a stress of about 710 MPa. This mode of fracture was observed at and below 873 K with the total ductility being less than 2.5%. However, the failure mode changed to dimpled fracture, triple point cracking and rupture above 873 K. Scanning electron microscopy of the fracture surfaces revealed that transgranular cleavage failure had always originated at pre-existing defects. In these cases, the fracture stress exhibited a good correlation with the defect size in accordance with linear elastic fracture mechanics, where the critical stress intensity factor was estimated to be about 4 MPa m1/2.
NiAl has only three independent slip systems operating at low and intermediate temperatures whereas five independent deformation mechanisms are required to satisfy the von Mises criterion for general plasticity in polycrystalline materials. Yet, it is generally recognized that polycrystalline NiAl can be deformed extensively in compression at room temperature and that limited tensile ductility can be obtained in extruded materials. In order to determine whether these results are in conflict with the von Mises criterion, tension and compression tests were conducted on powder-extruded, binary NiAl between 300 and 1300 K. The results indicate that below the brittle-to-ductile transition temperature (BDTT) the failure mechanism in NiAl involves the initiation and propagation of cracks at the grain boundaries which is consistent with the von Mises analysis. Furthermore, evaluation of the flow behavior of NiAl indicates that the transition from brittle to ductile behavior with increasing temperature coincides with the onset of recovery mechanisms such as dislocation climb. The increase in ductility above the BDTT is therefore attributed to the climb of <001> type dislocations which in combination with dislocation glide enable grain boundary compatibility to be maintained at the higher temperatures.
This study focuses on the sequential formation of aluminide phases during annealing of titanium and aluminum thin film bilayers. The formation of titanium-rich intermetallic phases at higher annealing temperatures is emphasized. Using Rutherford Backscattering Spectrometry (RBS) analysis, and x-ray diffraction, phases formed as a function of temperature have been identified. The phases Al3Ti through Ti3Al were observed over the temperature range 450–750°C, where reaction with the SiO2 substrate occurred. All phases were present as discreet layers within the samples with several layered phases coexisting at the higher temperatures.
Self supporting thin films of amorphous alumina and zirconia were irradiated with light and heavy ions at various temperatures(25–430°C). Irradiation was found to result in the formation of 10–30 nm large grains well below conventional crystallization temperatures. These grains were quite stable against subsequent thermal growth. Crystallization, grain size, and growth depended on ion species as well as on ‘stabilizing’ additives (yttria or Pt).
The hydroxyapatite (HAP) adsorption of salivary statherin, cystatins, proline-rich proteins and histatins has been compared to the influence of these molecules on HAP crystallization in supersaturated solution. This may yield, in many cases, information about protein conformation in the adsorbed state. The results of studies involving both parent molecules and their fragments, indicated that statherin binds to HAP primarily with a 2–5 residues segment in the N-terminal part while the cystatins and proline-rich proteins bind through a segment 2–3 times larger.
Semiconducting oxides are widely known and commercially applied for their gas sensing properties. However, biochemical sensing has mostly depended on optical and electrochemical techniques that are more cumbersome. This work investigates the biosensing characteristics of ZnO nanobelts and ZnO thin films. Zinc oxide thin film sensors showed changes in conductivity after protein functionalization with rabbit IgG and hybridization with anti-rabbit IgG. Conductivity changes were also measured after coating the oxides with MCF-7 cancer cells and its antibodies. In another set of experiments, ZnO nanobelts showed systematic conductivity changes with rabbit IgG protein hybridization. The experimental results in this paper indicate that the conductimetric properties of nano and thin film oxides can be sensitized to protein and cancer cell hybridization reactions. This technique can also be applied to certain other pathogen proteins or toxic proteins from the environment leading to low-cost miniaturized wireless biosensors.
This paper reports the results of the aerosol lidar experiments that have been performed at the Indian Institute of Tropical Meteorology (IITM), Pune (18.54°N, 73.85°E, 559 m amsl), a tropical station in India. The lidar-observed cloud macro-physical parameters (cloud-base and cloud-ceiling heights, vertical thickness, etc.) and polarisation characteristics and their association with surface-generated aerosols at the experimental site are presented and discussed. The correspondence among the lidar-derived aerosol distributions, meteorological parameters and south-west (SW) monsoon (June-September) activity over Pune during 12 successive SW monsoon seasons (1987-98) including two pairs of contrasting seasons of 1987-8 and 1993-4 is also examined. The results indicate an association between variations in aerosol loading in the boundary layer during the pre-monsoon season (March-May) and precipitation intensity during the ensuing monsoon season. Moreover, the decrease in aerosol content from pre-monsoon to monsoon season is found to follow the SW monsoon season total precipitation. Thus the results suggest that (i) the IITM lidar can also be a useful remote sensor for aerosol characterisation studies from polarisation measurements, and some important physical properties of clouds in the lower atmosphere over the station, and (ii) there exists a correspondence between boundary-layer aerosol content and SW monsoon precipitation over Pune, which is explained in terms of the type of aerosols and the environmental and meteorological processes, particularly during pre-monsoon and monsoon months prevailing over the experimental station.