Homogeneous photosensitization of complex TiO 2 nanostructures for efficient solar energy conversion

TiO 2 nanostructures-based photoelectrochemical (PEC) cells are under worldwide attentions as the method to generate clean energy. For these devices, narrow-bandgap semiconductor photosensitizers such as CdS and CdSe are commonly used to couple with TiO 2 in order to harvest the visible sunlight and to enhance the conversion efficiency. Conventional methods for depositing the photosensitizers on TiO 2 such as dip coating, electrochemical deposition and chemical-vapor-deposition suffer from poor control in thickness and uniformity, and correspond to low photocurrent levels. Here we demonstrate a new method based on atomic layer deposition and ion exchange reaction (ALDIER) to achieve a highly controllable and homogeneous coating of sensitizer particles on arbitrary TiO 2 substrates. PEC tests made to CdSe-sensitized TiO 2 inverse opal photoanodes result in a drastically improved photocurrent level, up to ∼15.7 mA/cm 2 at zero bias (vs Ag/AgCl), more than double that by conventional techniques such as successive ionic layer adsorption and reaction

A review on electronic bio-sensing approaches based on non-antibody recognition elements

In this review, recent advances in the development of electronic detection methodologies based on non-antibody recognition elements such as functional liposomes, aptamers and synthetic peptides are discussed. Particularly, we highlight the progress of field effect transistor (FET) sensing platforms where possible as the number of publications on FET-based platforms has increased rapidly. Biosensors involving antibody-antigen interactions have been widely applied in diagnostics and healthcare in virtue of their superior selectivity and sensitivity, which can be attributed to their high binding affinity and extraordinary specificity, respectively. However, antibodies typically suffer from fragile and complicated functional structures, large molecular size and sophisticated preparation approaches (resource-intensive and time-consuming), resulting in limitations such as short shelf-life, insufficient stability and poor reproducibility. Recently, bio-sensing approaches based on synthetic elements have been intensively explored. In contrast to existing reports, this review provides a comprehensive overview of recent advances in the development of biosensors utilizing synthetic recognition elements and a detailed comparison of their assay performances. Therefore, this review would serve as a good summary of the efforts for the development of electronic bio-sensing approaches involving synthetic recognition elements

The extended growth of graphene oxide flakes using ethanol CVD

We report the extended growth of Graphene Oxide (GO) flakes using atmospheric pressure ethanol Chemical Vapor Deposition (CVD). GO was used to catalyze the deposition of carbon on substrate in the ethanol CVD with Ar and H2 as carrier gases. Raman, SEM, XPS 10 and AFM characterized the growth to be reduced GO (RGO) of <5 layers. This new grown RGO possesses lower defect density with larger and increased distribution of sp2 domains than chemically-reduced RGO. Furthermore this method without optimization reduces relative standard deviation of electrical conductivity between chips, from 80.5% to 16.5%, enabling RGO to be used in practical electronic devices

The detection and measurement of interleukin-6 in venous and capillary blood samples, and in sweat collected at rest and during exercise

Purpose: This study aimed to quantify the relationship between venous and capillary blood sampling methods for the measurement of plasma interleukin-6 (IL-6). A parallel study was conducted to determine the possibility of measuring IL-6 in sweat using an enzyme-linked immunosorbent assay (ELISA) and investigate the relationship between plasma- and sweat-derived measures of IL-6. Methods: Twelve male participants were recruited for the measurement of IL-6 at rest and during exercise (study 1). An additional group of five female participants was recruited for the measurement of IL-6 in venous blood versus sweat at rest and following exercise (study 2). In study 1, venous and capillary blood samples were collected at rest and in response to exercise. In study 2, venous and sweat samples were collected following exercise. Results: Mean plasma IL-6 concentration was not different between venous and capillary blood sampling methods either at rest (4.27 ± 5.40 vs. 4.14 ± 4.45 pg ml−1), during (5.40 ± 5.17 vs. 5.58 ± 6.34 pg ml−1), or in response to exercise (6.95 ± 6.37 vs. 6.99 ± 6.74 pg ml−1). There was no IL-6 detectable in sweat either at rest or following exercise. Conclusion: There are no differences in the measurement of plasma IL-6 using either venous or capillary blood sampling methods. Capillary measurement represents a minimally invasive way of measuring IL-6 and detecting changes in IL-6, which are linked to fatigue and overtraining

Detection of matrilysin (MMP-7) activity using polypeptide functionalized reduced graphene oxide field-effect transistor sensor.

A novel approach for rapid and sensitive detection of matrilysin (MMP-7, a biomarker involved in the degradation of vari-ous macromolecules) based on polypeptide (JR2EC) functionalized reduced graphene oxide (rGO) field effect transistor (FET) is reported. MMP-7 specifically digests negatively charged JR2EC immobilized on rGO, thereby modulating the con-ductance of rGO-FET. The proposed assay enabled detection of MMP-7 at clinically relevant concentrations with a limit of detection (LOD) of 10 ng/mL (400 pM), attributed to the significant reduction of the net charge of JR2EC upon digestion by MMP-7. Quantitative detection of MMP-7 in human plasma was further demonstrated with a LOD of 40 ng/mL, illustrating the potential for the proposed methodology for tumor detection and carcinoma diagnostic (e.g. lung cancer and salivary gland cancer). Additionally, excellent specificity of the proposed assay was demonstrated using matrix metallopeptidase 1 (MMP-1), a protease of the same family. With appropriate selection and modification of polypeptides, the proposed assay could be extended for detections of other enzymes with polypeptide digestion capability

Aluminum nitride dielectric substrates with controlled porosity by reaction sintering

The thesis solved the two problems exist in the sintering of AIN. The two problems are pure AIN does not sinter to fully densification, and the adverse formation of the spinel phase, AION, occurs above 1700 deg. celsius.Doctor of Philosophy (MPE

In Situ Observation of Shear-Induced Jamming Front Propagation during Low-Velocity Impact in Polypropylene Glycol/Fumed Silica Shear Thickening Fluids

Shear jamming, a relatively new type of phase transition from discontinuous shear thickening into a solid-like state driven by shear in dense suspensions, has been shown to originate from frictional interactions between particles. However, not all dense suspensions shear jam. Dense fumed silica colloidal systems have wide applications in the industry of smart materials from body armor to dynamic dampers due to extremely low bulk density and high colloid stability. In this paper, we provide new evidence of shear jamming in polypropylene glycol/fumed silica suspensions using optical in situ speed recording during low-velocity impact and explain how it contributes to impact absorption. Flow rheology confirmed the presence of discontinuous shear thickening at all studied concentrations. Calculations of the flow during impact reveal that front propagation speed is 3&ndash;5 times higher than the speed of the impactor rod, which rules out jamming by densification, showing that the cause of the drastic impact absorption is the shear jamming. The main impact absorption begins when the jamming front reaches the boundary, creating a solid-like plug under the rod that confronts its movement. These results provide important insights into the impact absorption mechanism in fumed silica suspensions with a focus on shear jamming

Synthesis and crystal structure characterization of silicate apatite Sr2Y8(SiO4)6O2

Pure Sr2Y8(SiO4)6O2 powders were obtained after a solid-state reaction at 1400 °C for 6 h using the nanosized Y2O3, commercial SrCO3, and silica gel. The nanosized Y2O3 powder was synthesized by a precipitation method using Y(NO3)3 and NH4HCO3, followed by a heat treatment. The crystal structure of Sr2Y8(SiO4)6O2 was characterized by powder X-ray diffraction, Rietveld refinement, and high-resolution transmission electron microscopy. Results show that Sr2Y8(SiO4)6O2 has a typical apatite-type structure AI4AII6(BO4)6X2 in the P63/m space group. The lattice parameters are a=9.3884(6) Å and c=6.8657(4) Å. There are two special sites, AI (4f) and AII (6h), in the apatite structure. The AII sites are fully occupied by Y, while the AI sites are randomly filled by Y and Sr atoms. The crystallographic data obtained from Sr2Y8(SiO4)6O2 and other silicate oxyapatites are compared and summarized.Accepted versio

Horizontally Aligned Carbon Nanotube Based Biosensors for Protein Detection

A novel horizontally aligned single-walled carbon nanotube (CNT) Field Effect Transistor (FET)-based biosensing platform for real-time and sensitive protein detections is proposed. Aligned nanotubes were synthesized on quartz substrate using catalyst contact stamping, surface-guided morphological growth and chemical vapor deposition gas-guided growth methods. Real-time detection of prostate-specific antigen (PSA) using as-prepared FET biosensors was demonstrated. The kinetic measurements of the biosensor revealed that the drain current (Id) decreased exponentially as the concentration of PSA increased, indicating that the proposed FET sensor is capable of quantitative protein detection within a detection window of up to 1 µM. The limit of detection (LOD) achieved by the proposed platform was demonstrated to be 84 pM, which is lower than the clinically relevant level (133 pM) of PSA in blood. Additionally, the reported aligned CNT biosensor is a uniform sensing platform that could be extended to real-time detections of various biomarkers

Mono-distributed single-walled carbon nanotube channel in field effect transistors (FETs) using electrostatic atomization deposition

This communication reports on the novel work of creating a transistor channel based on functionalized single-walled carbon nanotubes (SWNTs) via electrostatic atomization deposition. The current method of drop-cast though convenient was unable to produce replicable transistor device due to its inherent inability in controlling the volume of liquid being drop-cast. Hence, this method of electrostatic atomization was introduced to consistently obtain a uniformly distributed SWNT channel resulting in a good transistor device.Accepted versio