Superparamagnetic iron oxide nanoparticle attachment on array of micro test tubes and microbeakers formed on p-type silicon substrate for biosensor applications

A uniformly distributed array of micro test tubes and microbeakers is formed on a p-type silicon substrate with tunable cross-section and distance of separation by anodic etching of the silicon wafer in N, N-dimethylformamide and hydrofluoric acid, which essentially leads to the formation of macroporous silicon templates. A reasonable control over the dimensions of the structures could be achieved by tailoring the formation parameters, primarily the wafer resistivity. For a micro test tube, the cross-section (i.e., the pore size) as well as the distance of separation between two adjacent test tubes (i.e., inter-pore distance) is typically approximately 1 μm, whereas, for a microbeaker the pore size exceeds 1.5 μm and the inter-pore distance could be less than 100 nm. We successfully synthesized superparamagnetic iron oxide nanoparticles (SPIONs), with average particle size approximately 20 nm and attached them on the porous silicon chip surface as well as on the pore walls. Such SPION-coated arrays of micro test tubes and microbeakers are potential candidates for biosensors because of the biocompatibility of both silicon and SPIONs. As acquisition of data via microarray is an essential attribute of high throughput bio-sensing, the proposed nanostructured array may be a promising step in this direction

Accelerating Medicines Partnership® Schizophrenia (AMP® SCZ): Rationale and Study Design of the Largest Global Prospective Cohort Study of Clinical High Risk for Psychosis

This article describes the rationale, aims, and methodology of the Accelerating Medicines Partnership® Schizophrenia (AMP® SCZ). This is the largest international collaboration to date that will develop algorithms to predict trajectories and outcomes of individuals at clinical high risk (CHR) for psychosis and to advance the development and use of novel pharmacological interventions for CHR individuals. We present a description of the participating research networks and the data processing analysis and coordination center, their processes for data harmonization across 43 sites from 13 participating countries (recruitment across North America, Australia, Europe, Asia, and South America), data flow and quality assessment processes, data analyses, and the transfer of data to the National Institute of Mental Health (NIMH) Data Archive (NDA) for use by the research community. In an expected sample of approximately 2000 CHR individuals and 640 matched healthy controls, AMP SCZ will collect clinical, environmental, and cognitive data along with multimodal biomarkers, including neuroimaging, electrophysiology, fluid biospecimens, speech and facial expression samples, novel measures derived from digital health technologies including smartphone-based daily surveys, and passive sensing as well as actigraphy. The study will investigate a range of clinical outcomes over a 2-year period, including transition to psychosis, remission or persistence of CHR status, attenuated positive symptoms, persistent negative symptoms, mood and anxiety symptoms, and psychosocial functioning. The global reach of AMP SCZ and its harmonized innovative methods promise to catalyze the development of new treatments to address critical unmet clinical and public health needs in CHR individuals

Optical and Structural Characterization of Reduced Graphene Oxide

In the present M. Tech thesis Graphene oxide is synthesized by hydrazine hydrate and L-ascorbic acid. Carbon nano-dots and carbon nano-tubes are formed as a part of thesis work by chemical synthesis route using Graphene with hydrazine hydrate. The carbon nano-dots and carbon nano-tubes along with Graphene layer structure were characterized by atomic force Microscope (AFM), Transmission Electron Microscope (TEM) and Raman spectroscopy. The particle sizes are characterized in the region of 5.0-5.5 nm and 8.0-8.5 nm. Generally particle size between 5.0-5.5 nm are called as nano-dots

Charge Transfer Induced Encapsulation of Si Quantum Dots by Atomically Larger and Highly Lattice-Mismatched Au Nanoparticles

Semiconductor–metal hybrid nanostructures are extremely promising candidates for exploring fundamental physics and chemistry of small systems and have multifarious potential applications. However, most of the synthesis techniques result in the formation of core–shell nanostructures with the atomically larger entity comprising the core, and allows moderate lattice-mismatch between the materials of the core and the shell. In this work we demonstrate the synthesis of a stable hybrid core–shell nanocomposite, consisting of Si quantum dots encapsulated by atomically larger and highly lattice-mismatched Au nanoparticles, induced by charge transfer between the two species. The semiconductor–metal hybrid system exhibits strong and stable room temperature photoluminescence with a substantially high quantum yield of 17.1%. Structural and spectroscopic investigations confirm the encapsulation of light emitting Si quantum dots by several Au nanoparticles, which consequently restrict surface oxidation of the quantum dots and effectively stabilizes the emission spectrum. These luminescent heteronanostructures have huge potential applications ranging from energy harvesting to bioimaging

Electrical transport through pelletized tablet of silicene like quasi 2D crystalline silicon

Silicene, the silicon-based 2D analogue of graphene, is predicted to have many exotic properties. However, most of the theoretically predicted phenomena have not yet been experimentally verified. In this work, we have prepared silicene-like, quasi 2D nanostructures via topochemical exfoliation of layered silicide and hot-pressed the dried powders to form bulk pellets. Temperature dependent electrical transport characteristics of pelletized silicene were investigated and found to exhibit evidence of some theoretically predicted features. The current–voltage (I-V) characteristics of the pelletized samples are non-linear, asymmetric about V = 0 and bears clear signature of negative differential resistance (NDR). The heuristic study provides interesting insights into the transport properties of bulk pellets of silicene and opens up the possibility of many applications

Tunable charge transport through n-ZnO nanorods on Au coated macroporous p-Si

We report a strategy to synthesize patterned n-ZnO nanorods on Au coated macroporous p-Si. Electric field assisted growth of ZnO under UV exposure results in the formation of well-aligned and relatively defect-free n-ZnO nanorods on the macroporous Si-template. The luminescence characteristics of ZnO exhibit a single Gaussian peak due to band-to-band transition in ZnO. Temperature dependent electrical transport through the n-ZnO/Au/p-Si heterojunction reveals unusual characteristics. Under forward bias, the I-V plots are diode-like with a remarkably low turn-on voltage and significantly high forward bias current. The non-linear forward current decreases appreciably with temperature while the reverse bias current is linear and is almost temperature independent. The Au layer present between the n-ZnO and p-Si significantly modifies the junction and allows tuning the device characteristics from diode-like to ohmic under different biasing conditions

Silicon and silicon oxide core-shell nanoparticles: Structural and photoluminescence characteristics

We report the synthesis of spherical core-shell structures of silicon and silicon oxide by a novel route of forced external oxidation of ball milled silicon. Structural investigations reveal the formation of a crystalline silicon core surrounded by an amorphous oxide shell, with core and shell dimensions varying approximately between 4-10 and 55-170 nm, respectively. The observations suggest partial amorphization of crystalline silicon, invasive oxygen induced passivation of dangling bonds, and formation of different types of defects in the nanocrystalline silicon/silicon oxide core-shell structure, particularly at the interfaces. No detectable photoluminescence (PL) is obtained from the as-milled silicon, but the oxidized core-shell structures exhibit strong room temperature PL, detectable with unaided eye. The peak energy of the PL spectra blueshifts with an increase in excitation energy, with the peak positions varying from 2.24 to 2.48 eV under external excitation ranging from 2.41 to 3.5 eV. The observed PL characteristics are explained in terms of dominant electronic transitions between the localized defect states and quantum confinement induced widened band states. c 2009 American Institute of Physics. [DOI: 10.1063/1.3100045

Superparamagnetic iron oxide nanoparticle attachment on array of micro test tubes and microbeakers formed on p-type silicon substrate for biosensor applications

<p>Abstract</p> <p>A uniformly distributed array of micro test tubes and microbeakers is formed on a p-type silicon substrate with tunable cross-section and distance of separation by anodic etching of the silicon wafer in N, N-dimethylformamide and hydrofluoric acid, which essentially leads to the formation of macroporous silicon templates. A reasonable control over the dimensions of the structures could be achieved by tailoring the formation parameters, primarily the wafer resistivity. For a micro test tube, the cross-section (i.e., the pore size) as well as the distance of separation between two adjacent test tubes (i.e., inter-pore distance) is typically approximately 1 &#956;m, whereas, for a microbeaker the pore size exceeds 1.5 &#956;m and the inter-pore distance could be less than 100 nm. We successfully synthesized superparamagnetic iron oxide nanoparticles (SPIONs), with average particle size approximately 20 nm and attached them on the porous silicon chip surface as well as on the pore walls. Such SPION-coated arrays of micro test tubes and microbeakers are potential candidates for biosensors because of the biocompatibility of both silicon and SPIONs. As acquisition of data via microarray is an essential attribute of high throughput bio-sensing, the proposed nanostructured array may be a promising step in this direction.</p

Performance Enhancement of Crystalline Silicon Solar Cells by Coating with Luminescent Silicon Nanostructures

In this work we report a technique that is potentially capable of increasing the efficiency of crystalline silicon solar cells, which dominate the present-day market of photovoltaic devices. The simple and cost-effective method involves coating the surface of a commercially procured silicon solar cell with luminescent silicon nanocrystals. Core/shell silicon/silicon-oxide nanostructures are fabricated by an inexpensive and reproducible technique, where coarse silicon powders are repeatedly milled, oxidized, and etched until their sizes are reduced so as to exhibit room-temperature photoluminescence under ultraviolet excitation. A thin coating of these nanostructures on a standard solar cell, obtained by a simple dip-coating method, increases the open-circuit voltage and short-circuit current, which consequently increases the maximum power delivered by 16.3% and efficiency by almost 39%. We propose that the core/shell nanostructures act as luminescent convertors that convert higher-energy photons to lower-energy photons, thereby leading to less thermal relaxation loss of photoexcited carriers