Examination of UV-Cross-Linkable Di-Block Copolymer Strategy for Functionalized Reaction Surface on Microelectrode Arrays

Microarrays are powerful tools for high-throughput screening of small molecule libraries. Our group is using a microelectrode array variant on these efforts that allows us to construct and screen the libraries in a rapid, cost effective fashion. In this approach, the small molecules are attached to polymer-coated microelectrodes, which can be used to detect ligand-receptor interactions as they happen by means of impedance. Impedance experiment work by monitoring the current associated with a redox couple in solution. When a protein binds a ligand on the array, it sterically prevents the redox couple from reaching the electrode surface and thus causes a reduction in the current being measured. In order to realize the construction of a library and measurement of the electrochemical impedance on the array, the polymer coating applied on the array needs to be stable for long periods of time, stable to washing the array, compatible with the array-based reactions, compatible with electrochemical impedance experiments, and relatively inert with respect to its non-specific binding with receptors. This work makes progress towards this goal by first exploring the Pd(0) chemistry on the array, identifying the incompatibility of palladium chemistry with the agarose coating that was being used on the surface of the arrays, and the designing and synthesizing new polymer coatings for microelectrode arrays. Three different block copolymers were made to investigate the compatibility of the polymers with the array-based reactions and signaling experiments. All three types of polymers consisted of a PCEMA block for UV-cross-linking reactions to improve the stability of the coating. The prototype polymer PBrSt-b-CEMA used 4-bromostyrene as the second block for functionalization purpose. It was proven to be a very versatile polymer which was stable, and compatible with all the electrochemical experiments conducted on the array. As a result this coating was extensively utilized in the study of the behavior of signaling experiments on the array. The major drawback of this polymer was its non-specific binding to proteins at higher protein concentrations. In order to fix this problem, a second polymer PCEMA-b-PEGMA with PEG as side chains was made in the hope that PEG would reduce non-specific binding to the surface. Unfortunately the polymer was not stable enough as coating for the array. Finally, a copolymer with boronic acid functionality, PCEMA-b-BoSt was made in order to test the versatility of the boronic acid as a starting material for building other functionalities. The boronic acid derived polymer performs better than the previous coating in terms of array-based reactions. However, it was found to be incompatible with the electrochemical impedance experiments

Low-cost virtual instrumentation system of an energy-dispersive X-ray spectrometer for a scanning electron microscope

The paper describes an energy-dispersive X-ray spectrometer for a scanning electron microscope (SEM-EDXS). It was constructed using the new architecture of a virtual instrument (VI), which is low-cost, space-saving, fast and flexible way to develop the instrument. Computer-aided teaching (CAT) was used to develop the instrument and operation rather than a traditional instrument technique. The VI was designed using the object-oriented program language C++ and compact programmable logical devices (CPLD). These include spectra collection and processing, quantitative analysis and X-ray-intensity distribution analysis. The procedure is described in detail. The VI system gives an e¡ective and user-friendly human interface for the whole analytical task. Some examples are described

Auto-analysis system for graphite morphology of grey cast iron

The current method to classify graphite morphology types of grey cast iron is based on traditional subjective observation, and it cannot be used for quantitative analysis. Since microstructures have a great effect on the mechanical properties of grey cast iron and different types have totally different characters, six types of grey cast iron are discussed and an image-processing software subsystem that performs the classification and quantitative analysis automatically based on a kind of composed feature vector and artificial neural network (ANN) is described. There are three kinds of texture features: fractal dimension, roughness and two-dimension autoregression, which are used as an extracted feature input vector of ANN classifier. Compared with using only one, the checkout correct precision increased greatly. On the other hand, to achieve the quantitative analysis and show the different types clearly, the region segmentation idea was applied to the system. The percentages of the regions with different type are reported correctly. Furthermore, this paper tentatively introduces a new empirical method to decide the number of ANN hidden nodes, which are usually considered as a difficulty in ANN structure decision. It was found that the optimum hidden node number of the experimental data was the same as that obtained using the new method

Tidal wind mapping from observations of a meteor radar chain in December 2011

This article proposes a technique to map the tidal winds in the mesosphere and lower thermosphere (MLT) region from the observations of a four-station meteor radar chain located at middle- and low-latitudes along the 120 degrees E meridian in the Northern Hemisphere. A 1month dataset of the horizontal winds in the altitude range of 80-100km is observed during December 2011. We first decompose the tidal winds into mean, diurnal, semidiurnal, and terdiurnal components for each station. It is found that the diurnal/semidiurnal components dominate at the low-latitude/midlatitude stations. Their amplitudes increase at lower altitudes and then decrease at higher altitudes after reaching a peak in the MLT region. Hough functions of the classical tidal theory are then used to fit the latitudinal distribution of each decomposed component. The diurnal component is found to be dominated by the first symmetric (1, 1) mode. Yet for the semidiurnal and terdiurnal components, the corresponding dominant modes are the second symmetric modes (2, 4) and (3, 5), and considerable contributions are also from the first antisymmetric modes (2, 3), (3, 4) and second antisymmetric modes (2, 5), (3, 6). Based on the decomposed results, we further map the horizontal winds in the domains of latitude, altitude and local time. The mapped horizontal winds successfully reproduce the local time versus altitudinal distributions of the original observations at the four stations. Thus, we conclude that the meteor radar chain is useful to monitor and study the regional characteristics of the tidal winds in the MLT region

Impact Response Comparison Between Parametric Human Models and Postmortem Human Subjects with a Wide Range of Obesity Levels

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138906/1/oby21947_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138906/2/oby21947.pd

A Facile and Generic Strategy to Synthesize Large-Scale Carbon Nanotubes

An easy method to prepare carbon nanotubes (CNTs) has been demonstrated using a two-step refluxing and calcination process. First, a readily available inorganic salt, Ni(NO3)2⋅6H2O, used as the catalyst precursor was dissolved in the high-boiling-point organic solvents (alcohols or polyhydric alcohol) by refluxing at 190∘C for 3 hours. After refluxing, NiO nanoparticles obtained in the solution act as the catalyst, and the organic refluxing solvents are used as the carbon source for the growth of CNTs. Second, CNTs are prepared by calcining the refluxed solution at 800∘C in an N2 atmosphere for 3 hours. Results show that CNT growth possibly originates from carbon rings, with the nanotube walls growing perpendicular to these rings and forming a closed tube at the end

Certificateless Key Insulated Encryption: Cryptographic Primitive for Achieving Key-escrow free and Key-exposure Resilience

Certificateless encryption (CLE) alleviates the heavy certificate management in traditional public key encryption and the key escrow problem in the ID-based encryption simultaneously. Current CLE schemes assumed that the user’s secret key is absolutely secure. Unfortunately, this assumption is too strong in case the CLE is deployed in the hostile setting and the leakage of secret key is inevitable. In this paper, we present a new concept called an certificateless key insulated encryption scheme (CL-KIE). We argue that this is an important cryptographic primitive that can be used to achieve key-escrow free and key-exposure resilience. We also present an efficient CL-KIE scheme based on bilinear pairing. After that, the security of our scheme is proved under the Bilinear Diffie-Hellman assumption in the random oracle model. Certificateless encryption (CLE) alleviates the heavy certificate management in traditional public key encryption and the key escrow problem in the ID-based encryption simultaneously. Current CLE schemes assumed that the user’s secret key is absolutely secure. Unfortunately, this assumption is too strong in case the CLE is deployed in the hostile setting and the leakage of the secret key is inevitable. In this paper, we present a new concept called a certificateless key insulated encryption scheme (CL-KIE). We argue that this is an important cryptographic primitive that can be used to achieve key-escrow free and key-exposure resilience. We also present an efficient CL-KIE scheme based on bilinear pairing. After that, the security of our scheme is proved under the Bilinear DiffieHellman assumption in the random oracle model

Preparation and Photocatalytic Performance of Ti 3

Ti3C2/TiO2/CuO nanocomposites were synthesized via the decomposition of a mixture of Ti3C2 (a novel two-dimensional carbide) and cupric nitrate under an argon atmosphere. The morphology and structures of the obtained samples were characterized. X-ray diffraction and energy dispersive spectrometer analysis indicate that the sample is composed of Ti3C2, anatase-TiO2, and CuO. Scanning electron microscopy images show that CuO and TiO2 nanoparticles were evenly distributed on the surface of Ti3C2. The particles size increased with an increase in the cupric nitrate content. Photocatalytic degradation of methyl orange shows that the Ti3C2/TiO2/CuO nanocomposite has good photocatalytic degradation efficiency. A possible photocatalytic mechanism of the Ti3C2/TiO2/CuO nanocomposites was proposed. The data indicated that CuO and Ti3C2 effectively promote the separation of photoelectrons from vacancies