Wafer-scale nanopatterning and translation into high-performance piezoelectric nanowires

The development of a facile method for fabricating one-dimensional, precisely positioned nanostructures over large areas offers exciting opportunities in fundamental research and innovative applications. Large-scale nanofabrication methods have been restricted in accessibility due to their complexity and cost. Likewise, bottom-up synthesis of nanowires has been limited in methods to assemble these structures at precisely defined locations. Nanomaterials such as PbZr(x)Ti(1-x)O(3) (PZT) nanowires (NWs)--which may be useful for nonvolatile memory storage (FeRAM), nanoactuation, and nanoscale power generation--are difficult to synthesize without suffering from polycrystallinity or poor stoichiometric control. Here, we report a novel fabrication method which requires only low-resolution photolithography and electrochemical etching to generate ultrasmooth NWs over wafer scales. These nanostructures are subsequently used as patterning templates to generate PZT nanowires with the highest reported piezoelectric performance (d(eff) ～ 145 pm/V). The combined large-scale nanopatterning with hierarchical assembly of functional nanomaterials could yield breakthroughs in areas ranging from nanodevice arrays to nanodevice powering.     

Mounted nanoporous anodic alumina thin films as planar optical waveguides

Solid-supported thin films of self-organized nanoporous anodic aluminum oxide (AAO) have been widely employed for the template preparation of nanostructured functional materials. Recently, the use of nanoporous AAO thin films in optical waveguide spectroscopy (OWS) has been explored for high sensitivity, in situ monitoring of processes occurring within these nanoporous templates. In this contribution, we demonstrate a strategy for mounting bulk anodized AAO thin films on heterogeneous solid-supports suitable for waveguide sensing experiments. Unlike conventional preparations of AAO thin films by anodization of vacuum- or electrochemically deposited Al thin films, the full range of techniques available to anodize bulk Al may potentially be applied with the present method. Moreover, we show that AAO thin films mounted on glass substrates can have superior waveguide coupling properties compared to conventionally prepared samples. The nanostructure of the AAO can be well characterized by an EMT-OWS analysis, demonstrated by comparing scanning electron microscopy images of the AAO and the pore dimensions calculated from an effective medium theory (EMT) analysis of the film refractive index measured by OWS. Finally, using a curved metallic substrate as an example, we show that our mounting technique can be used as a general strategy to functionalize objects with nanoporous AAO films.     

Quantitative measurement of urinary excretion of 3-hydroxyisovaleryl carnitine by LC-MS/MS as an indicator of biotin status in humans

Abnormally increased urinary excretion of 3-hydroxyisovaleryl carnitine (3HIA-carnitine) results from impairment in leucine catabolism caused by reduced activity of the biotin-dependent enzyme 3-methylcrotonyl-CoA carboxylase. Accordingly, urinary 3HIA-carnitine might reflect biotin status. Here, we describe an LC-MS/MS method for accurately quantitating the urinary concentration of 3HIA-carnitine at concentrations that are typical for excretion rates that are normal or only modestly increased. This method allows for high sample throughput and does not require solid-phase extraction. We used this method to provide evidence validating urinary 3HIA-carnitine as a biomarker of biotin deficiency in humans. Four healthy adult subjects were successfully made marginally biotin deficient by feeding a 30% egg white diet for 28 days. From study day 0 to 28, the mean urinary excretion of 3HIA-carnitine increased 3.5-fold (p = 0.026). These preliminary results indicate that urinary excretion of 3HIA-carnitine increases with marginal biotin deficiency. If these results are confirmed in studies involving larger numbers of subjects, urinary excretion of 3HIA-carnitine may potentially be a clinically useful indicator of biotin status.     

Flow cytometric analysis to detect pathogens in bacterial cell mixtures using semiconductor quantum dots

Compared to a common green organic dye, semiconductor quantum dots (QDs) composed of CdSe/ZnS core/shell bioconjugates display brighter fluorescence intensities, lower detection thresholds, and better accuracy in analyzing bacterial cell mixtures composed of pathogenic E. coli O157:H7 and harmless E. coli DH5alpha using flow cytometry. For the same given bacterial mixture, QDs display fluorescence intensity levels that are approximately 1 order of magnitude brighter compared to the analogous experiments that utilize the standard dye fluorescein isothiocyanate. Detection limits are lowest when QDs are used as the fluorophore label for the pathogenic E. coli O157:H7 serotype: limits of 1% O157:H7 in 99% DH5alpha result, corresponding to 106 cells/mL, which is comparable to other developing fluorescence-based techniques for pathogen detection. Finally, utilizing QDs to label E. coli O157:H7 in cell mixtures results in greater accuracy and more closely approaches the ideal fluorophore for pathogen detection using flow cytometry. With their broader absorption spectra and narrower emission spectra than organic dyes, QDs can make vast improvements in the field of flow cytometry, where single-source excitation and simultaneous detection of multicolor species without complicating experimental setups or data analysis is quite advantageous for analyzing heterogeneous cell mixtures, both for prokaryotic pathogen detection and for studies on eukaryotic cell characteristics.     

Quantitation of steroid hormones in thin fresh frozen tissue sections

As analytical technologies in proteomics and metabolomics continue to mature, there is an increasing need to apply these to clinically relevant biologic samples. In this study, a liquid chromatography-tandem mass spectrometry method that utilizes selected reaction monitoring was used to measure the absolute quantity of estrogens and estrogen metabolites and testosterone in 8-microm tissue sections obtained from a fresh frozen lymph node tumor infiltrated by metastatic breast carcinoma. Total (conjugated plus unconjugated) and unconjugated levels of these steroid hormones were measured using two cohorts, each containing five adjacent serial sections cut from this tumor. The results were highly reproducible across replicate samples, showing that typical histological tissue sections represent an important sample type for the measurement of these specific metabolites.     

Unsupervised clustering approaches to color classification for color-based image code recognition

Color-vision-based applications for mobile phones has become a subject of special interest lately. It would be interesting to investigate an unsupervised, adaptive, and fast algorithm that can classify color components into color clusters. We propose a hierarchical clustering approach using a single-linkage algorithm and a k-means clustering approach to color classification for color-based image code recognition in mobile computing environments. We also measured the performance of the proposed algorithms by color channel stretch, which is a simple color-correction method. Experimental results show that the single-linkage method is more robust than previous algorithms used in experiments with varying cameras and print materials. In particular the k-means-based method with color channel stretching has the highest performance and is the most robust under varying environment conditions such as illuminants, cameras, and print materials.     

Monitoring the intracellular pH of Zygosaccharomyces bailii by green fluorescent protein

It is generally known that intracellular pH (pH(i)) plays a vital role in cell physiology and that pH(i) homeostasis is essential for normal cellular functions. Therefore, it is desirable to know the pH(i) during cell life cycle or under various growth conditions. Different methods to measure pH(i) have been developed and among these methods, the use of pH-sensitive green fluorescent protein (GFP) as a pH(i) indicator is a promising technique. By using this approach, not only can more accurate pH(i) results be obtained but also long-term experiments on pH(i) can be performed. In this study, the wild type Zygosaccharomyces bailii, a notorious food spoilage yeast, was transformed with a plasmid encoding a pH-sensitive GFP (i.e. pHluorin), enabling the pH(i) of the yeast to be determined based on cellular fluorescent signals. After the transformation, growth and pH(i) of the yeast were investigated in four different acidic conditions at 22°C during 26days. From the experimental results, the transformation effectiveness was verified and a good correlation between yeast growth and pH(i) was noticed. Particularly, it was observed that the yeast has an ability to tolerate a significant pH(i) drop during exponential phase and a subsequent pH(i) recovery in stationary phase, which may underlie the exceptional acid resistance of the yeast. This was the first time that a GFP-based approach for pH(i) measurement was applied in Z. bailii and that the pH(i) of the yeast was monitored during such a long period (26days). It can be expected that greater understanding of the physiological properties and mechanisms behind the special acid resistance of the yeast will be obtained from further studies on this new yeast strain.     

The labile lipid fraction of meat: from perceived disease and waste to health and opportunity

The fatty acid composition of beef and pork has been stigmatized due to their relationships with several diseases from cardiovascular disease to cancer. Meat lipids are, however, one of the few components of meat that can be modified in content and composition, and can present opportunities for value added production and health promotion. Until regulations and policies are in place to define requirements for fatty acid enrichment, however, the process remains relatively academic. Once practical goals are in place for fatty acid enrichment in meat, both theory and practice need to converge for successful production of fatty acid enriched meat. The present review covers aspects of policy in Canada, and requirements for research networks to respond to theoretical and practical challenges associated with production of fatty acid enriched meat. Finally, needs for education and marketing are outlined which must be in place to truly realize a transition of meat lipids from perceived disease and waste to health and opportunity.