Relative Price Variability and Inflation: Evidence from US Cities

We test whether the time-series positive correlation of inflation and intermarket relative price variability is also present in a cross-section of US cities. We find this correlation to be a robust empirical regularity: cities which have higher than average inflation also have higher than average relative price dispersion, ceteris paribus. This result holds for different periods of time, different classes of goods, and across different time horizons. Our results suggest that at least part of the relationship between inflation and relative price variability cannot be explained by monetary factors.

A Dry Etch Approach To Reduce Roughness And Eliminate Visible Grind Marks In Silicon Wafers Post Back-grind

3D wafer packaging represents a significant component of the total wafer level processing cost. Replacement of the Chemical Mechanical Polishing (CMP) process step with a corresponding dry etch can yield significant time and cost savings. Incorporating equipment already utilized in the 3D integrated wafer packaging process during the subsequent Through Silicon Via (TSV) reveal step, process efficiencies can be achieved, with overall die yields being maintained. Using dry etch technology to treat a 200nm rough back-ground silicon surface, a smooth surface with a peak to valley roughness of less than 6nm is demonstrated. This patented process differs from other dry etch smoothing techniques in that it aims to eliminate any visual grind marks rather than just reducing the surface roughness. The elimination of visible grind marks is critical in later optical inspection where they are falsely identified as defects. The quality of the surface is equivalent to that of a CMP processed wafer and as such, this process has been implemented in manufacturing replacing the CMP step. The novel process described combines a surface modification followed by a roughness reduction in an iterative manner to produce a smooth surface without visible grind marks post processing

Electrochemical Biofunctionalization of Highly Oriented Pyrolytic Graphite for Immunosensor Applications

The present research demonstrates a procedure for surface modification of Highly Oriented Pyrolytic Graphite (HOPG) electrodes intended for use as immunosensors. The HOPG surface is linked to the molecule 8-hydroxydeoxyguanosine (8-OHdG), an oxidative stress biomarker for DNA damage, though the aniline mediator covalently bonded to electrode and biomarker. An electrochemical procedure to graft the mediator is described and the presence of biomarker at surface is demonstrated by using a fluorescence-labeled immune-reagent. An electrochemical functionalization process has been employed for attachment of functional aminie (NH2) linking groups to graphitic surfaces, which consists of two stages: (i) a reaction with a diazonium salt to covalently bond nitrobenzene groups to the surface and (ii) electrochemical reduction of the nitro group (–NO2) to an amine group (–NH2). The shape of the CV curve indicates that the redox reactions are taking place at the HOPG electrode surface. The amine group can subsequently be used to covalently link to an antibody biorecptor. The presence of 8-OHdG, indicative of DNA damage, has been linked to increased cancer risk. Detection of this oxidative stress biomarker is an important tool for the early diagnosis of disease

MIL-101(Cr), an Efficient Heterogeneous Catalyst for One Pot Synthesis of 2,4,5-tri Substituted Imidazoles under Solvent Free Conditions

A chromium-containing metal-organic framework (MOF), MIL-101 (Chromium(III) benzene-1,4-dicarboxylate), was used to catalyze the one pot, three component synthesis of some 2,4,5-trisubstituted imidazoles under solvent-free conditions. The advantages of using this heterogeneous catalyst include short reaction time, high yields, easy and quick isolation of catalyst and products, low amount of catalyst needed, and that the addition of solvent, salt, and additives are not needed. This catalyst is highly efficient and can be recovered at least 5 times with a slight loss of efficiency. The structure of the metal-organic frameworks (MOF) was confirmed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (HNMR) were performed to confirm some of the synthesized products. Experimental data indicated that the optimum amount of catalyst was 5 mg for benzil (1 mmol), 4-chlorobenzaldehyde (1 mmol), and ammonium acetate (2.5 mmol), and the synthetic route to the various imidazoles is performed in 10 min by 95% yield, an acceptable result rivalling those of other catalysts

Enhanced thermoelectric performance of monolayer MoSSe, bilayer MoSSe and graphene/MoSSe heterogeneous nanoribbons

Graphene has many superlative thermal, electrical and mechanical properties. However, the thermoelectric performance of graphene is limited by its high thermal conductivity and small Seebeck coefficient. To address this problem, monolayer and bilayer MoSSe nanoribbons together with graphene/MoSSe heterostructures have been investigated in this work. The electron and phonon transport, and the thermoelectric properties of the monolayer and bilayer MoSSe nanoribbons, together with the graphene/MoSSe heterostructures, have been analyzed by first-principles methods in conjunction with non-equilibrium Green's function and the Landauer equation. The results indicate that figure of merit (ZT) values of 2.01 and 1.64 can be achieved for graphene/SeMoS stacked nanoribbons and symmetric armchair MoSSe nanoribbons respectively at 300 K, which are much higher than the ZT value of prime graphene (ZT ∼ 0.05). The maximum ZT values of these structures increase at T 350 K). However, the maximum ZT values of the symmetric armchair MoSSe nanoribbons show an increase with temperatures up to 550 K. From our analysis, phonon thermal conductivity and temperature are key factors determining the ZT values in MoSSe nanoribbons. The significantly enhanced ZT values make graphene/SeMoS stacking nanoribbons and symmetric armchair MoSSe nanoribbons promising candidates for application in thermoelectric devices

Graphene based electrochemical immunosensor for the ultra-sensitive label free detection of Alzheimer's beta amyloid peptides Aβ(1–42)

An immunosensor capable of high sensitivity detection of beta-amyloid peptides, shown to be a reliable biomarker for Alzheimer's disease, has been developed using screen printed graphene electrodes (SPGEs) modified with ultra-thin layers of polymerised 1,5-diaminonaphthalene (pDAN). Electropolymerization of 1,5-diaminonaphthalene (DAN) was performed to coat the graphene screen printed electrodes in a continuous polymer layer with controlled thickness. The surface characteristics of pristine graphene and polymer modified graphene electrodes were examined using Raman and X-ray photoelectron spectroscopy. The effects of polymer thickness on the electron transfer rates were investigated. An immunosensor for selective detection of beta amyloid peptides Aβ(1–42) was developed via biofunctionalization of the pDAN modified SPGE with the anti-beta amyloid antibody used as the peptide bioreceptor. The immunosensor has been used for specific detection of Aβ(1–42) with a linear range of 1 pg mL−1 to 1000 pg mL−1 and showed 1.4 pg mL−1 and 4.25 pg mL−1 detection and quantification limit, respectively. The biosensor was further validated for the analysis of spiked human plasma. The immunosensor enables rapid, accurate, precise, reproducible and highly sensitive detection of Aβ(1–42) using a low-cost SPGE platform, which opens the possibilities for diagnostic ex vivo applications and research-based real time studies

Graphene Field Effect Transistors for Biomedical Applications: Current Status and Future Prospects

Since the discovery of the two-dimensional (2D) carbon material, graphene, just over a decade ago, the development of graphene-based field effect transistors (G-FETs) has become a widely researched area, particularly for use in point-of-care biomedical applications. G-FETs are particularly attractive as next generation bioelectronics due to their mass-scalability and low cost of the technology’s manufacture. Furthermore, G-FETs offer the potential to complete label-free, rapid, and highly sensitive analysis coupled with a high sample throughput. These properties, coupled with the potential for integration into portable instrumentation, contribute to G-FETs’ suitability for point-of-care diagnostics. This review focuses on elucidating the recent developments in the field of G-FET sensors that act on a bioaffinity basis, whereby a binding event between a bioreceptor and the target analyte is transduced into an electrical signal at the G-FET surface. Recognizing and quantifying these target analytes accurately and reliably is essential in diagnosing many diseases, therefore it is vital to design the G-FET with care. Taking into account some limitations of the sensor platform, such as Debye–Hükel screening and device surface area, is fundamental in developing improved bioelectronics for applications in the clinical setting. This review highlights some efforts undertaken in facing these limitations in order to bring G-FET development for biomedical applications forward